Version:  2.0.40 2.2.26 2.4.37 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16

Linux/drivers/md/raid5.c

  1 /*
  2  * raid5.c : Multiple Devices driver for Linux
  3  *         Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
  4  *         Copyright (C) 1999, 2000 Ingo Molnar
  5  *         Copyright (C) 2002, 2003 H. Peter Anvin
  6  *
  7  * RAID-4/5/6 management functions.
  8  * Thanks to Penguin Computing for making the RAID-6 development possible
  9  * by donating a test server!
 10  *
 11  * This program is free software; you can redistribute it and/or modify
 12  * it under the terms of the GNU General Public License as published by
 13  * the Free Software Foundation; either version 2, or (at your option)
 14  * any later version.
 15  *
 16  * You should have received a copy of the GNU General Public License
 17  * (for example /usr/src/linux/COPYING); if not, write to the Free
 18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 19  */
 20 
 21 /*
 22  * BITMAP UNPLUGGING:
 23  *
 24  * The sequencing for updating the bitmap reliably is a little
 25  * subtle (and I got it wrong the first time) so it deserves some
 26  * explanation.
 27  *
 28  * We group bitmap updates into batches.  Each batch has a number.
 29  * We may write out several batches at once, but that isn't very important.
 30  * conf->bm_write is the number of the last batch successfully written.
 31  * conf->bm_flush is the number of the last batch that was closed to
 32  *    new additions.
 33  * When we discover that we will need to write to any block in a stripe
 34  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
 35  * the number of the batch it will be in. This is bm_flush+1.
 36  * When we are ready to do a write, if that batch hasn't been written yet,
 37  *   we plug the array and queue the stripe for later.
 38  * When an unplug happens, we increment bm_flush, thus closing the current
 39  *   batch.
 40  * When we notice that bm_flush > bm_write, we write out all pending updates
 41  * to the bitmap, and advance bm_write to where bm_flush was.
 42  * This may occasionally write a bit out twice, but is sure never to
 43  * miss any bits.
 44  */
 45 
 46 #include <linux/blkdev.h>
 47 #include <linux/kthread.h>
 48 #include <linux/raid/pq.h>
 49 #include <linux/async_tx.h>
 50 #include <linux/async.h>
 51 #include <linux/seq_file.h>
 52 #include <linux/cpu.h>
 53 #include <linux/slab.h>
 54 #include "md.h"
 55 #include "raid5.h"
 56 #include "raid0.h"
 57 #include "bitmap.h"
 58 
 59 /*
 60  * Stripe cache
 61  */
 62 
 63 #define NR_STRIPES              256
 64 #define STRIPE_SIZE             PAGE_SIZE
 65 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
 66 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
 67 #define IO_THRESHOLD            1
 68 #define BYPASS_THRESHOLD        1
 69 #define NR_HASH                 (PAGE_SIZE / sizeof(struct hlist_head))
 70 #define HASH_MASK               (NR_HASH - 1)
 71 
 72 #define stripe_hash(conf, sect) (&((conf)->stripe_hashtbl[((sect) >> STRIPE_SHIFT) & HASH_MASK]))
 73 
 74 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
 75  * order without overlap.  There may be several bio's per stripe+device, and
 76  * a bio could span several devices.
 77  * When walking this list for a particular stripe+device, we must never proceed
 78  * beyond a bio that extends past this device, as the next bio might no longer
 79  * be valid.
 80  * This macro is used to determine the 'next' bio in the list, given the sector
 81  * of the current stripe+device
 82  */
 83 #define r5_next_bio(bio, sect) ( ( (bio)->bi_sector + ((bio)->bi_size>>9) < sect + STRIPE_SECTORS) ? (bio)->bi_next : NULL)
 84 /*
 85  * The following can be used to debug the driver
 86  */
 87 #define RAID5_PARANOIA  1
 88 #if RAID5_PARANOIA && defined(CONFIG_SMP)
 89 # define CHECK_DEVLOCK() assert_spin_locked(&conf->device_lock)
 90 #else
 91 # define CHECK_DEVLOCK()
 92 #endif
 93 
 94 #ifdef DEBUG
 95 #define inline
 96 #define __inline__
 97 #endif
 98 
 99 #define printk_rl(args...) ((void) (printk_ratelimit() && printk(args)))
100 
101 /*
102  * We maintain a biased count of active stripes in the bottom 16 bits of
103  * bi_phys_segments, and a count of processed stripes in the upper 16 bits
104  */
105 static inline int raid5_bi_phys_segments(struct bio *bio)
106 {
107         return bio->bi_phys_segments & 0xffff;
108 }
109 
110 static inline int raid5_bi_hw_segments(struct bio *bio)
111 {
112         return (bio->bi_phys_segments >> 16) & 0xffff;
113 }
114 
115 static inline int raid5_dec_bi_phys_segments(struct bio *bio)
116 {
117         --bio->bi_phys_segments;
118         return raid5_bi_phys_segments(bio);
119 }
120 
121 static inline int raid5_dec_bi_hw_segments(struct bio *bio)
122 {
123         unsigned short val = raid5_bi_hw_segments(bio);
124 
125         --val;
126         bio->bi_phys_segments = (val << 16) | raid5_bi_phys_segments(bio);
127         return val;
128 }
129 
130 static inline void raid5_set_bi_hw_segments(struct bio *bio, unsigned int cnt)
131 {
132         bio->bi_phys_segments = raid5_bi_phys_segments(bio) || (cnt << 16);
133 }
134 
135 /* Find first data disk in a raid6 stripe */
136 static inline int raid6_d0(struct stripe_head *sh)
137 {
138         if (sh->ddf_layout)
139                 /* ddf always start from first device */
140                 return 0;
141         /* md starts just after Q block */
142         if (sh->qd_idx == sh->disks - 1)
143                 return 0;
144         else
145                 return sh->qd_idx + 1;
146 }
147 static inline int raid6_next_disk(int disk, int raid_disks)
148 {
149         disk++;
150         return (disk < raid_disks) ? disk : 0;
151 }
152 
153 /* When walking through the disks in a raid5, starting at raid6_d0,
154  * We need to map each disk to a 'slot', where the data disks are slot
155  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
156  * is raid_disks-1.  This help does that mapping.
157  */
158 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
159                              int *count, int syndrome_disks)
160 {
161         int slot = *count;
162 
163         if (sh->ddf_layout)
164                 (*count)++;
165         if (idx == sh->pd_idx)
166                 return syndrome_disks;
167         if (idx == sh->qd_idx)
168                 return syndrome_disks + 1;
169         if (!sh->ddf_layout)
170                 (*count)++;
171         return slot;
172 }
173 
174 static void return_io(struct bio *return_bi)
175 {
176         struct bio *bi = return_bi;
177         while (bi) {
178 
179                 return_bi = bi->bi_next;
180                 bi->bi_next = NULL;
181                 bi->bi_size = 0;
182                 bio_endio(bi, 0);
183                 bi = return_bi;
184         }
185 }
186 
187 static void print_raid5_conf (raid5_conf_t *conf);
188 
189 static int stripe_operations_active(struct stripe_head *sh)
190 {
191         return sh->check_state || sh->reconstruct_state ||
192                test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
193                test_bit(STRIPE_COMPUTE_RUN, &sh->state);
194 }
195 
196 static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
197 {
198         if (atomic_dec_and_test(&sh->count)) {
199                 BUG_ON(!list_empty(&sh->lru));
200                 BUG_ON(atomic_read(&conf->active_stripes)==0);
201                 if (test_bit(STRIPE_HANDLE, &sh->state)) {
202                         if (test_bit(STRIPE_DELAYED, &sh->state)) {
203                                 list_add_tail(&sh->lru, &conf->delayed_list);
204                                 plugger_set_plug(&conf->plug);
205                         } else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
206                                    sh->bm_seq - conf->seq_write > 0) {
207                                 list_add_tail(&sh->lru, &conf->bitmap_list);
208                                 plugger_set_plug(&conf->plug);
209                         } else {
210                                 clear_bit(STRIPE_BIT_DELAY, &sh->state);
211                                 list_add_tail(&sh->lru, &conf->handle_list);
212                         }
213                         md_wakeup_thread(conf->mddev->thread);
214                 } else {
215                         BUG_ON(stripe_operations_active(sh));
216                         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
217                                 atomic_dec(&conf->preread_active_stripes);
218                                 if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
219                                         md_wakeup_thread(conf->mddev->thread);
220                         }
221                         atomic_dec(&conf->active_stripes);
222                         if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
223                                 list_add_tail(&sh->lru, &conf->inactive_list);
224                                 wake_up(&conf->wait_for_stripe);
225                                 if (conf->retry_read_aligned)
226                                         md_wakeup_thread(conf->mddev->thread);
227                         }
228                 }
229         }
230 }
231 
232 static void release_stripe(struct stripe_head *sh)
233 {
234         raid5_conf_t *conf = sh->raid_conf;
235         unsigned long flags;
236 
237         spin_lock_irqsave(&conf->device_lock, flags);
238         __release_stripe(conf, sh);
239         spin_unlock_irqrestore(&conf->device_lock, flags);
240 }
241 
242 static inline void remove_hash(struct stripe_head *sh)
243 {
244         pr_debug("remove_hash(), stripe %llu\n",
245                 (unsigned long long)sh->sector);
246 
247         hlist_del_init(&sh->hash);
248 }
249 
250 static inline void insert_hash(raid5_conf_t *conf, struct stripe_head *sh)
251 {
252         struct hlist_head *hp = stripe_hash(conf, sh->sector);
253 
254         pr_debug("insert_hash(), stripe %llu\n",
255                 (unsigned long long)sh->sector);
256 
257         CHECK_DEVLOCK();
258         hlist_add_head(&sh->hash, hp);
259 }
260 
261 
262 /* find an idle stripe, make sure it is unhashed, and return it. */
263 static struct stripe_head *get_free_stripe(raid5_conf_t *conf)
264 {
265         struct stripe_head *sh = NULL;
266         struct list_head *first;
267 
268         CHECK_DEVLOCK();
269         if (list_empty(&conf->inactive_list))
270                 goto out;
271         first = conf->inactive_list.next;
272         sh = list_entry(first, struct stripe_head, lru);
273         list_del_init(first);
274         remove_hash(sh);
275         atomic_inc(&conf->active_stripes);
276 out:
277         return sh;
278 }
279 
280 static void shrink_buffers(struct stripe_head *sh)
281 {
282         struct page *p;
283         int i;
284         int num = sh->raid_conf->pool_size;
285 
286         for (i = 0; i < num ; i++) {
287                 p = sh->dev[i].page;
288                 if (!p)
289                         continue;
290                 sh->dev[i].page = NULL;
291                 put_page(p);
292         }
293 }
294 
295 static int grow_buffers(struct stripe_head *sh)
296 {
297         int i;
298         int num = sh->raid_conf->pool_size;
299 
300         for (i = 0; i < num; i++) {
301                 struct page *page;
302 
303                 if (!(page = alloc_page(GFP_KERNEL))) {
304                         return 1;
305                 }
306                 sh->dev[i].page = page;
307         }
308         return 0;
309 }
310 
311 static void raid5_build_block(struct stripe_head *sh, int i, int previous);
312 static void stripe_set_idx(sector_t stripe, raid5_conf_t *conf, int previous,
313                             struct stripe_head *sh);
314 
315 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
316 {
317         raid5_conf_t *conf = sh->raid_conf;
318         int i;
319 
320         BUG_ON(atomic_read(&sh->count) != 0);
321         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
322         BUG_ON(stripe_operations_active(sh));
323 
324         CHECK_DEVLOCK();
325         pr_debug("init_stripe called, stripe %llu\n",
326                 (unsigned long long)sh->sector);
327 
328         remove_hash(sh);
329 
330         sh->generation = conf->generation - previous;
331         sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
332         sh->sector = sector;
333         stripe_set_idx(sector, conf, previous, sh);
334         sh->state = 0;
335 
336 
337         for (i = sh->disks; i--; ) {
338                 struct r5dev *dev = &sh->dev[i];
339 
340                 if (dev->toread || dev->read || dev->towrite || dev->written ||
341                     test_bit(R5_LOCKED, &dev->flags)) {
342                         printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
343                                (unsigned long long)sh->sector, i, dev->toread,
344                                dev->read, dev->towrite, dev->written,
345                                test_bit(R5_LOCKED, &dev->flags));
346                         BUG();
347                 }
348                 dev->flags = 0;
349                 raid5_build_block(sh, i, previous);
350         }
351         insert_hash(conf, sh);
352 }
353 
354 static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector,
355                                          short generation)
356 {
357         struct stripe_head *sh;
358         struct hlist_node *hn;
359 
360         CHECK_DEVLOCK();
361         pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
362         hlist_for_each_entry(sh, hn, stripe_hash(conf, sector), hash)
363                 if (sh->sector == sector && sh->generation == generation)
364                         return sh;
365         pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
366         return NULL;
367 }
368 
369 /*
370  * Need to check if array has failed when deciding whether to:
371  *  - start an array
372  *  - remove non-faulty devices
373  *  - add a spare
374  *  - allow a reshape
375  * This determination is simple when no reshape is happening.
376  * However if there is a reshape, we need to carefully check
377  * both the before and after sections.
378  * This is because some failed devices may only affect one
379  * of the two sections, and some non-in_sync devices may
380  * be insync in the section most affected by failed devices.
381  */
382 static int has_failed(raid5_conf_t *conf)
383 {
384         int degraded;
385         int i;
386         if (conf->mddev->reshape_position == MaxSector)
387                 return conf->mddev->degraded > conf->max_degraded;
388 
389         rcu_read_lock();
390         degraded = 0;
391         for (i = 0; i < conf->previous_raid_disks; i++) {
392                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
393                 if (!rdev || test_bit(Faulty, &rdev->flags))
394                         degraded++;
395                 else if (test_bit(In_sync, &rdev->flags))
396                         ;
397                 else
398                         /* not in-sync or faulty.
399                          * If the reshape increases the number of devices,
400                          * this is being recovered by the reshape, so
401                          * this 'previous' section is not in_sync.
402                          * If the number of devices is being reduced however,
403                          * the device can only be part of the array if
404                          * we are reverting a reshape, so this section will
405                          * be in-sync.
406                          */
407                         if (conf->raid_disks >= conf->previous_raid_disks)
408                                 degraded++;
409         }
410         rcu_read_unlock();
411         if (degraded > conf->max_degraded)
412                 return 1;
413         rcu_read_lock();
414         degraded = 0;
415         for (i = 0; i < conf->raid_disks; i++) {
416                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
417                 if (!rdev || test_bit(Faulty, &rdev->flags))
418                         degraded++;
419                 else if (test_bit(In_sync, &rdev->flags))
420                         ;
421                 else
422                         /* not in-sync or faulty.
423                          * If reshape increases the number of devices, this
424                          * section has already been recovered, else it
425                          * almost certainly hasn't.
426                          */
427                         if (conf->raid_disks <= conf->previous_raid_disks)
428                                 degraded++;
429         }
430         rcu_read_unlock();
431         if (degraded > conf->max_degraded)
432                 return 1;
433         return 0;
434 }
435 
436 static void unplug_slaves(mddev_t *mddev);
437 
438 static struct stripe_head *
439 get_active_stripe(raid5_conf_t *conf, sector_t sector,
440                   int previous, int noblock, int noquiesce)
441 {
442         struct stripe_head *sh;
443 
444         pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
445 
446         spin_lock_irq(&conf->device_lock);
447 
448         do {
449                 wait_event_lock_irq(conf->wait_for_stripe,
450                                     conf->quiesce == 0 || noquiesce,
451                                     conf->device_lock, /* nothing */);
452                 sh = __find_stripe(conf, sector, conf->generation - previous);
453                 if (!sh) {
454                         if (!conf->inactive_blocked)
455                                 sh = get_free_stripe(conf);
456                         if (noblock && sh == NULL)
457                                 break;
458                         if (!sh) {
459                                 conf->inactive_blocked = 1;
460                                 wait_event_lock_irq(conf->wait_for_stripe,
461                                                     !list_empty(&conf->inactive_list) &&
462                                                     (atomic_read(&conf->active_stripes)
463                                                      < (conf->max_nr_stripes *3/4)
464                                                      || !conf->inactive_blocked),
465                                                     conf->device_lock,
466                                                     md_raid5_unplug_device(conf)
467                                         );
468                                 conf->inactive_blocked = 0;
469                         } else
470                                 init_stripe(sh, sector, previous);
471                 } else {
472                         if (atomic_read(&sh->count)) {
473                                 BUG_ON(!list_empty(&sh->lru)
474                                     && !test_bit(STRIPE_EXPANDING, &sh->state));
475                         } else {
476                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
477                                         atomic_inc(&conf->active_stripes);
478                                 if (list_empty(&sh->lru) &&
479                                     !test_bit(STRIPE_EXPANDING, &sh->state))
480                                         BUG();
481                                 list_del_init(&sh->lru);
482                         }
483                 }
484         } while (sh == NULL);
485 
486         if (sh)
487                 atomic_inc(&sh->count);
488 
489         spin_unlock_irq(&conf->device_lock);
490         return sh;
491 }
492 
493 static void
494 raid5_end_read_request(struct bio *bi, int error);
495 static void
496 raid5_end_write_request(struct bio *bi, int error);
497 
498 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
499 {
500         raid5_conf_t *conf = sh->raid_conf;
501         int i, disks = sh->disks;
502 
503         might_sleep();
504 
505         for (i = disks; i--; ) {
506                 int rw;
507                 struct bio *bi;
508                 mdk_rdev_t *rdev;
509                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
510                         if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
511                                 rw = WRITE_FUA;
512                         else
513                                 rw = WRITE;
514                 } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
515                         rw = READ;
516                 else
517                         continue;
518 
519                 bi = &sh->dev[i].req;
520 
521                 bi->bi_rw = rw;
522                 if (rw == WRITE)
523                         bi->bi_end_io = raid5_end_write_request;
524                 else
525                         bi->bi_end_io = raid5_end_read_request;
526 
527                 rcu_read_lock();
528                 rdev = rcu_dereference(conf->disks[i].rdev);
529                 if (rdev && test_bit(Faulty, &rdev->flags))
530                         rdev = NULL;
531                 if (rdev)
532                         atomic_inc(&rdev->nr_pending);
533                 rcu_read_unlock();
534 
535                 if (rdev) {
536                         if (s->syncing || s->expanding || s->expanded)
537                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
538 
539                         set_bit(STRIPE_IO_STARTED, &sh->state);
540 
541                         bi->bi_bdev = rdev->bdev;
542                         pr_debug("%s: for %llu schedule op %ld on disc %d\n",
543                                 __func__, (unsigned long long)sh->sector,
544                                 bi->bi_rw, i);
545                         atomic_inc(&sh->count);
546                         bi->bi_sector = sh->sector + rdev->data_offset;
547                         bi->bi_flags = 1 << BIO_UPTODATE;
548                         bi->bi_vcnt = 1;
549                         bi->bi_max_vecs = 1;
550                         bi->bi_idx = 0;
551                         bi->bi_io_vec = &sh->dev[i].vec;
552                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
553                         bi->bi_io_vec[0].bv_offset = 0;
554                         bi->bi_size = STRIPE_SIZE;
555                         bi->bi_next = NULL;
556                         if (rw == WRITE &&
557                             test_bit(R5_ReWrite, &sh->dev[i].flags))
558                                 atomic_add(STRIPE_SECTORS,
559                                         &rdev->corrected_errors);
560                         generic_make_request(bi);
561                 } else {
562                         if (rw == WRITE)
563                                 set_bit(STRIPE_DEGRADED, &sh->state);
564                         pr_debug("skip op %ld on disc %d for sector %llu\n",
565                                 bi->bi_rw, i, (unsigned long long)sh->sector);
566                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
567                         set_bit(STRIPE_HANDLE, &sh->state);
568                 }
569         }
570 }
571 
572 static struct dma_async_tx_descriptor *
573 async_copy_data(int frombio, struct bio *bio, struct page *page,
574         sector_t sector, struct dma_async_tx_descriptor *tx)
575 {
576         struct bio_vec *bvl;
577         struct page *bio_page;
578         int i;
579         int page_offset;
580         struct async_submit_ctl submit;
581         enum async_tx_flags flags = 0;
582 
583         if (bio->bi_sector >= sector)
584                 page_offset = (signed)(bio->bi_sector - sector) * 512;
585         else
586                 page_offset = (signed)(sector - bio->bi_sector) * -512;
587 
588         if (frombio)
589                 flags |= ASYNC_TX_FENCE;
590         init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
591 
592         bio_for_each_segment(bvl, bio, i) {
593                 int len = bio_iovec_idx(bio, i)->bv_len;
594                 int clen;
595                 int b_offset = 0;
596 
597                 if (page_offset < 0) {
598                         b_offset = -page_offset;
599                         page_offset += b_offset;
600                         len -= b_offset;
601                 }
602 
603                 if (len > 0 && page_offset + len > STRIPE_SIZE)
604                         clen = STRIPE_SIZE - page_offset;
605                 else
606                         clen = len;
607 
608                 if (clen > 0) {
609                         b_offset += bio_iovec_idx(bio, i)->bv_offset;
610                         bio_page = bio_iovec_idx(bio, i)->bv_page;
611                         if (frombio)
612                                 tx = async_memcpy(page, bio_page, page_offset,
613                                                   b_offset, clen, &submit);
614                         else
615                                 tx = async_memcpy(bio_page, page, b_offset,
616                                                   page_offset, clen, &submit);
617                 }
618                 /* chain the operations */
619                 submit.depend_tx = tx;
620 
621                 if (clen < len) /* hit end of page */
622                         break;
623                 page_offset +=  len;
624         }
625 
626         return tx;
627 }
628 
629 static void ops_complete_biofill(void *stripe_head_ref)
630 {
631         struct stripe_head *sh = stripe_head_ref;
632         struct bio *return_bi = NULL;
633         raid5_conf_t *conf = sh->raid_conf;
634         int i;
635 
636         pr_debug("%s: stripe %llu\n", __func__,
637                 (unsigned long long)sh->sector);
638 
639         /* clear completed biofills */
640         spin_lock_irq(&conf->device_lock);
641         for (i = sh->disks; i--; ) {
642                 struct r5dev *dev = &sh->dev[i];
643 
644                 /* acknowledge completion of a biofill operation */
645                 /* and check if we need to reply to a read request,
646                  * new R5_Wantfill requests are held off until
647                  * !STRIPE_BIOFILL_RUN
648                  */
649                 if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
650                         struct bio *rbi, *rbi2;
651 
652                         BUG_ON(!dev->read);
653                         rbi = dev->read;
654                         dev->read = NULL;
655                         while (rbi && rbi->bi_sector <
656                                 dev->sector + STRIPE_SECTORS) {
657                                 rbi2 = r5_next_bio(rbi, dev->sector);
658                                 if (!raid5_dec_bi_phys_segments(rbi)) {
659                                         rbi->bi_next = return_bi;
660                                         return_bi = rbi;
661                                 }
662                                 rbi = rbi2;
663                         }
664                 }
665         }
666         spin_unlock_irq(&conf->device_lock);
667         clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
668 
669         return_io(return_bi);
670 
671         set_bit(STRIPE_HANDLE, &sh->state);
672         release_stripe(sh);
673 }
674 
675 static void ops_run_biofill(struct stripe_head *sh)
676 {
677         struct dma_async_tx_descriptor *tx = NULL;
678         raid5_conf_t *conf = sh->raid_conf;
679         struct async_submit_ctl submit;
680         int i;
681 
682         pr_debug("%s: stripe %llu\n", __func__,
683                 (unsigned long long)sh->sector);
684 
685         for (i = sh->disks; i--; ) {
686                 struct r5dev *dev = &sh->dev[i];
687                 if (test_bit(R5_Wantfill, &dev->flags)) {
688                         struct bio *rbi;
689                         spin_lock_irq(&conf->device_lock);
690                         dev->read = rbi = dev->toread;
691                         dev->toread = NULL;
692                         spin_unlock_irq(&conf->device_lock);
693                         while (rbi && rbi->bi_sector <
694                                 dev->sector + STRIPE_SECTORS) {
695                                 tx = async_copy_data(0, rbi, dev->page,
696                                         dev->sector, tx);
697                                 rbi = r5_next_bio(rbi, dev->sector);
698                         }
699                 }
700         }
701 
702         atomic_inc(&sh->count);
703         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
704         async_trigger_callback(&submit);
705 }
706 
707 static void mark_target_uptodate(struct stripe_head *sh, int target)
708 {
709         struct r5dev *tgt;
710 
711         if (target < 0)
712                 return;
713 
714         tgt = &sh->dev[target];
715         set_bit(R5_UPTODATE, &tgt->flags);
716         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
717         clear_bit(R5_Wantcompute, &tgt->flags);
718 }
719 
720 static void ops_complete_compute(void *stripe_head_ref)
721 {
722         struct stripe_head *sh = stripe_head_ref;
723 
724         pr_debug("%s: stripe %llu\n", __func__,
725                 (unsigned long long)sh->sector);
726 
727         /* mark the computed target(s) as uptodate */
728         mark_target_uptodate(sh, sh->ops.target);
729         mark_target_uptodate(sh, sh->ops.target2);
730 
731         clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
732         if (sh->check_state == check_state_compute_run)
733                 sh->check_state = check_state_compute_result;
734         set_bit(STRIPE_HANDLE, &sh->state);
735         release_stripe(sh);
736 }
737 
738 /* return a pointer to the address conversion region of the scribble buffer */
739 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
740                                  struct raid5_percpu *percpu)
741 {
742         return percpu->scribble + sizeof(struct page *) * (sh->disks + 2);
743 }
744 
745 static struct dma_async_tx_descriptor *
746 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
747 {
748         int disks = sh->disks;
749         struct page **xor_srcs = percpu->scribble;
750         int target = sh->ops.target;
751         struct r5dev *tgt = &sh->dev[target];
752         struct page *xor_dest = tgt->page;
753         int count = 0;
754         struct dma_async_tx_descriptor *tx;
755         struct async_submit_ctl submit;
756         int i;
757 
758         pr_debug("%s: stripe %llu block: %d\n",
759                 __func__, (unsigned long long)sh->sector, target);
760         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
761 
762         for (i = disks; i--; )
763                 if (i != target)
764                         xor_srcs[count++] = sh->dev[i].page;
765 
766         atomic_inc(&sh->count);
767 
768         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
769                           ops_complete_compute, sh, to_addr_conv(sh, percpu));
770         if (unlikely(count == 1))
771                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
772         else
773                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
774 
775         return tx;
776 }
777 
778 /* set_syndrome_sources - populate source buffers for gen_syndrome
779  * @srcs - (struct page *) array of size sh->disks
780  * @sh - stripe_head to parse
781  *
782  * Populates srcs in proper layout order for the stripe and returns the
783  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
784  * destination buffer is recorded in srcs[count] and the Q destination
785  * is recorded in srcs[count+1]].
786  */
787 static int set_syndrome_sources(struct page **srcs, struct stripe_head *sh)
788 {
789         int disks = sh->disks;
790         int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
791         int d0_idx = raid6_d0(sh);
792         int count;
793         int i;
794 
795         for (i = 0; i < disks; i++)
796                 srcs[i] = NULL;
797 
798         count = 0;
799         i = d0_idx;
800         do {
801                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
802 
803                 srcs[slot] = sh->dev[i].page;
804                 i = raid6_next_disk(i, disks);
805         } while (i != d0_idx);
806 
807         return syndrome_disks;
808 }
809 
810 static struct dma_async_tx_descriptor *
811 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
812 {
813         int disks = sh->disks;
814         struct page **blocks = percpu->scribble;
815         int target;
816         int qd_idx = sh->qd_idx;
817         struct dma_async_tx_descriptor *tx;
818         struct async_submit_ctl submit;
819         struct r5dev *tgt;
820         struct page *dest;
821         int i;
822         int count;
823 
824         if (sh->ops.target < 0)
825                 target = sh->ops.target2;
826         else if (sh->ops.target2 < 0)
827                 target = sh->ops.target;
828         else
829                 /* we should only have one valid target */
830                 BUG();
831         BUG_ON(target < 0);
832         pr_debug("%s: stripe %llu block: %d\n",
833                 __func__, (unsigned long long)sh->sector, target);
834 
835         tgt = &sh->dev[target];
836         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
837         dest = tgt->page;
838 
839         atomic_inc(&sh->count);
840 
841         if (target == qd_idx) {
842                 count = set_syndrome_sources(blocks, sh);
843                 blocks[count] = NULL; /* regenerating p is not necessary */
844                 BUG_ON(blocks[count+1] != dest); /* q should already be set */
845                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
846                                   ops_complete_compute, sh,
847                                   to_addr_conv(sh, percpu));
848                 tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
849         } else {
850                 /* Compute any data- or p-drive using XOR */
851                 count = 0;
852                 for (i = disks; i-- ; ) {
853                         if (i == target || i == qd_idx)
854                                 continue;
855                         blocks[count++] = sh->dev[i].page;
856                 }
857 
858                 init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
859                                   NULL, ops_complete_compute, sh,
860                                   to_addr_conv(sh, percpu));
861                 tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
862         }
863 
864         return tx;
865 }
866 
867 static struct dma_async_tx_descriptor *
868 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
869 {
870         int i, count, disks = sh->disks;
871         int syndrome_disks = sh->ddf_layout ? disks : disks-2;
872         int d0_idx = raid6_d0(sh);
873         int faila = -1, failb = -1;
874         int target = sh->ops.target;
875         int target2 = sh->ops.target2;
876         struct r5dev *tgt = &sh->dev[target];
877         struct r5dev *tgt2 = &sh->dev[target2];
878         struct dma_async_tx_descriptor *tx;
879         struct page **blocks = percpu->scribble;
880         struct async_submit_ctl submit;
881 
882         pr_debug("%s: stripe %llu block1: %d block2: %d\n",
883                  __func__, (unsigned long long)sh->sector, target, target2);
884         BUG_ON(target < 0 || target2 < 0);
885         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
886         BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
887 
888         /* we need to open-code set_syndrome_sources to handle the
889          * slot number conversion for 'faila' and 'failb'
890          */
891         for (i = 0; i < disks ; i++)
892                 blocks[i] = NULL;
893         count = 0;
894         i = d0_idx;
895         do {
896                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
897 
898                 blocks[slot] = sh->dev[i].page;
899 
900                 if (i == target)
901                         faila = slot;
902                 if (i == target2)
903                         failb = slot;
904                 i = raid6_next_disk(i, disks);
905         } while (i != d0_idx);
906 
907         BUG_ON(faila == failb);
908         if (failb < faila)
909                 swap(faila, failb);
910         pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
911                  __func__, (unsigned long long)sh->sector, faila, failb);
912 
913         atomic_inc(&sh->count);
914 
915         if (failb == syndrome_disks+1) {
916                 /* Q disk is one of the missing disks */
917                 if (faila == syndrome_disks) {
918                         /* Missing P+Q, just recompute */
919                         init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
920                                           ops_complete_compute, sh,
921                                           to_addr_conv(sh, percpu));
922                         return async_gen_syndrome(blocks, 0, syndrome_disks+2,
923                                                   STRIPE_SIZE, &submit);
924                 } else {
925                         struct page *dest;
926                         int data_target;
927                         int qd_idx = sh->qd_idx;
928 
929                         /* Missing D+Q: recompute D from P, then recompute Q */
930                         if (target == qd_idx)
931                                 data_target = target2;
932                         else
933                                 data_target = target;
934 
935                         count = 0;
936                         for (i = disks; i-- ; ) {
937                                 if (i == data_target || i == qd_idx)
938                                         continue;
939                                 blocks[count++] = sh->dev[i].page;
940                         }
941                         dest = sh->dev[data_target].page;
942                         init_async_submit(&submit,
943                                           ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
944                                           NULL, NULL, NULL,
945                                           to_addr_conv(sh, percpu));
946                         tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
947                                        &submit);
948 
949                         count = set_syndrome_sources(blocks, sh);
950                         init_async_submit(&submit, ASYNC_TX_FENCE, tx,
951                                           ops_complete_compute, sh,
952                                           to_addr_conv(sh, percpu));
953                         return async_gen_syndrome(blocks, 0, count+2,
954                                                   STRIPE_SIZE, &submit);
955                 }
956         } else {
957                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
958                                   ops_complete_compute, sh,
959                                   to_addr_conv(sh, percpu));
960                 if (failb == syndrome_disks) {
961                         /* We're missing D+P. */
962                         return async_raid6_datap_recov(syndrome_disks+2,
963                                                        STRIPE_SIZE, faila,
964                                                        blocks, &submit);
965                 } else {
966                         /* We're missing D+D. */
967                         return async_raid6_2data_recov(syndrome_disks+2,
968                                                        STRIPE_SIZE, faila, failb,
969                                                        blocks, &submit);
970                 }
971         }
972 }
973 
974 
975 static void ops_complete_prexor(void *stripe_head_ref)
976 {
977         struct stripe_head *sh = stripe_head_ref;
978 
979         pr_debug("%s: stripe %llu\n", __func__,
980                 (unsigned long long)sh->sector);
981 }
982 
983 static struct dma_async_tx_descriptor *
984 ops_run_prexor(struct stripe_head *sh, struct raid5_percpu *percpu,
985                struct dma_async_tx_descriptor *tx)
986 {
987         int disks = sh->disks;
988         struct page **xor_srcs = percpu->scribble;
989         int count = 0, pd_idx = sh->pd_idx, i;
990         struct async_submit_ctl submit;
991 
992         /* existing parity data subtracted */
993         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
994 
995         pr_debug("%s: stripe %llu\n", __func__,
996                 (unsigned long long)sh->sector);
997 
998         for (i = disks; i--; ) {
999                 struct r5dev *dev = &sh->dev[i];
1000                 /* Only process blocks that are known to be uptodate */
1001                 if (test_bit(R5_Wantdrain, &dev->flags))
1002                         xor_srcs[count++] = dev->page;
1003         }
1004 
1005         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1006                           ops_complete_prexor, sh, to_addr_conv(sh, percpu));
1007         tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1008 
1009         return tx;
1010 }
1011 
1012 static struct dma_async_tx_descriptor *
1013 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1014 {
1015         int disks = sh->disks;
1016         int i;
1017 
1018         pr_debug("%s: stripe %llu\n", __func__,
1019                 (unsigned long long)sh->sector);
1020 
1021         for (i = disks; i--; ) {
1022                 struct r5dev *dev = &sh->dev[i];
1023                 struct bio *chosen;
1024 
1025                 if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
1026                         struct bio *wbi;
1027 
1028                         spin_lock(&sh->lock);
1029                         chosen = dev->towrite;
1030                         dev->towrite = NULL;
1031                         BUG_ON(dev->written);
1032                         wbi = dev->written = chosen;
1033                         spin_unlock(&sh->lock);
1034 
1035                         while (wbi && wbi->bi_sector <
1036                                 dev->sector + STRIPE_SECTORS) {
1037                                 if (wbi->bi_rw & REQ_FUA)
1038                                         set_bit(R5_WantFUA, &dev->flags);
1039                                 tx = async_copy_data(1, wbi, dev->page,
1040                                         dev->sector, tx);
1041                                 wbi = r5_next_bio(wbi, dev->sector);
1042                         }
1043                 }
1044         }
1045 
1046         return tx;
1047 }
1048 
1049 static void ops_complete_reconstruct(void *stripe_head_ref)
1050 {
1051         struct stripe_head *sh = stripe_head_ref;
1052         int disks = sh->disks;
1053         int pd_idx = sh->pd_idx;
1054         int qd_idx = sh->qd_idx;
1055         int i;
1056         bool fua = false;
1057 
1058         pr_debug("%s: stripe %llu\n", __func__,
1059                 (unsigned long long)sh->sector);
1060 
1061         for (i = disks; i--; )
1062                 fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1063 
1064         for (i = disks; i--; ) {
1065                 struct r5dev *dev = &sh->dev[i];
1066 
1067                 if (dev->written || i == pd_idx || i == qd_idx) {
1068                         set_bit(R5_UPTODATE, &dev->flags);
1069                         if (fua)
1070                                 set_bit(R5_WantFUA, &dev->flags);
1071                 }
1072         }
1073 
1074         if (sh->reconstruct_state == reconstruct_state_drain_run)
1075                 sh->reconstruct_state = reconstruct_state_drain_result;
1076         else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1077                 sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1078         else {
1079                 BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1080                 sh->reconstruct_state = reconstruct_state_result;
1081         }
1082 
1083         set_bit(STRIPE_HANDLE, &sh->state);
1084         release_stripe(sh);
1085 }
1086 
1087 static void
1088 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1089                      struct dma_async_tx_descriptor *tx)
1090 {
1091         int disks = sh->disks;
1092         struct page **xor_srcs = percpu->scribble;
1093         struct async_submit_ctl submit;
1094         int count = 0, pd_idx = sh->pd_idx, i;
1095         struct page *xor_dest;
1096         int prexor = 0;
1097         unsigned long flags;
1098 
1099         pr_debug("%s: stripe %llu\n", __func__,
1100                 (unsigned long long)sh->sector);
1101 
1102         /* check if prexor is active which means only process blocks
1103          * that are part of a read-modify-write (written)
1104          */
1105         if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1106                 prexor = 1;
1107                 xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1108                 for (i = disks; i--; ) {
1109                         struct r5dev *dev = &sh->dev[i];
1110                         if (dev->written)
1111                                 xor_srcs[count++] = dev->page;
1112                 }
1113         } else {
1114                 xor_dest = sh->dev[pd_idx].page;
1115                 for (i = disks; i--; ) {
1116                         struct r5dev *dev = &sh->dev[i];
1117                         if (i != pd_idx)
1118                                 xor_srcs[count++] = dev->page;
1119                 }
1120         }
1121 
1122         /* 1/ if we prexor'd then the dest is reused as a source
1123          * 2/ if we did not prexor then we are redoing the parity
1124          * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1125          * for the synchronous xor case
1126          */
1127         flags = ASYNC_TX_ACK |
1128                 (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1129 
1130         atomic_inc(&sh->count);
1131 
1132         init_async_submit(&submit, flags, tx, ops_complete_reconstruct, sh,
1133                           to_addr_conv(sh, percpu));
1134         if (unlikely(count == 1))
1135                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1136         else
1137                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1138 }
1139 
1140 static void
1141 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1142                      struct dma_async_tx_descriptor *tx)
1143 {
1144         struct async_submit_ctl submit;
1145         struct page **blocks = percpu->scribble;
1146         int count;
1147 
1148         pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1149 
1150         count = set_syndrome_sources(blocks, sh);
1151 
1152         atomic_inc(&sh->count);
1153 
1154         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_reconstruct,
1155                           sh, to_addr_conv(sh, percpu));
1156         async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1157 }
1158 
1159 static void ops_complete_check(void *stripe_head_ref)
1160 {
1161         struct stripe_head *sh = stripe_head_ref;
1162 
1163         pr_debug("%s: stripe %llu\n", __func__,
1164                 (unsigned long long)sh->sector);
1165 
1166         sh->check_state = check_state_check_result;
1167         set_bit(STRIPE_HANDLE, &sh->state);
1168         release_stripe(sh);
1169 }
1170 
1171 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1172 {
1173         int disks = sh->disks;
1174         int pd_idx = sh->pd_idx;
1175         int qd_idx = sh->qd_idx;
1176         struct page *xor_dest;
1177         struct page **xor_srcs = percpu->scribble;
1178         struct dma_async_tx_descriptor *tx;
1179         struct async_submit_ctl submit;
1180         int count;
1181         int i;
1182 
1183         pr_debug("%s: stripe %llu\n", __func__,
1184                 (unsigned long long)sh->sector);
1185 
1186         count = 0;
1187         xor_dest = sh->dev[pd_idx].page;
1188         xor_srcs[count++] = xor_dest;
1189         for (i = disks; i--; ) {
1190                 if (i == pd_idx || i == qd_idx)
1191                         continue;
1192                 xor_srcs[count++] = sh->dev[i].page;
1193         }
1194 
1195         init_async_submit(&submit, 0, NULL, NULL, NULL,
1196                           to_addr_conv(sh, percpu));
1197         tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1198                            &sh->ops.zero_sum_result, &submit);
1199 
1200         atomic_inc(&sh->count);
1201         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1202         tx = async_trigger_callback(&submit);
1203 }
1204 
1205 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1206 {
1207         struct page **srcs = percpu->scribble;
1208         struct async_submit_ctl submit;
1209         int count;
1210 
1211         pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1212                 (unsigned long long)sh->sector, checkp);
1213 
1214         count = set_syndrome_sources(srcs, sh);
1215         if (!checkp)
1216                 srcs[count] = NULL;
1217 
1218         atomic_inc(&sh->count);
1219         init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1220                           sh, to_addr_conv(sh, percpu));
1221         async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1222                            &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1223 }
1224 
1225 static void __raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1226 {
1227         int overlap_clear = 0, i, disks = sh->disks;
1228         struct dma_async_tx_descriptor *tx = NULL;
1229         raid5_conf_t *conf = sh->raid_conf;
1230         int level = conf->level;
1231         struct raid5_percpu *percpu;
1232         unsigned long cpu;
1233 
1234         cpu = get_cpu();
1235         percpu = per_cpu_ptr(conf->percpu, cpu);
1236         if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1237                 ops_run_biofill(sh);
1238                 overlap_clear++;
1239         }
1240 
1241         if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1242                 if (level < 6)
1243                         tx = ops_run_compute5(sh, percpu);
1244                 else {
1245                         if (sh->ops.target2 < 0 || sh->ops.target < 0)
1246                                 tx = ops_run_compute6_1(sh, percpu);
1247                         else
1248                                 tx = ops_run_compute6_2(sh, percpu);
1249                 }
1250                 /* terminate the chain if reconstruct is not set to be run */
1251                 if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1252                         async_tx_ack(tx);
1253         }
1254 
1255         if (test_bit(STRIPE_OP_PREXOR, &ops_request))
1256                 tx = ops_run_prexor(sh, percpu, tx);
1257 
1258         if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1259                 tx = ops_run_biodrain(sh, tx);
1260                 overlap_clear++;
1261         }
1262 
1263         if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1264                 if (level < 6)
1265                         ops_run_reconstruct5(sh, percpu, tx);
1266                 else
1267                         ops_run_reconstruct6(sh, percpu, tx);
1268         }
1269 
1270         if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1271                 if (sh->check_state == check_state_run)
1272                         ops_run_check_p(sh, percpu);
1273                 else if (sh->check_state == check_state_run_q)
1274                         ops_run_check_pq(sh, percpu, 0);
1275                 else if (sh->check_state == check_state_run_pq)
1276                         ops_run_check_pq(sh, percpu, 1);
1277                 else
1278                         BUG();
1279         }
1280 
1281         if (overlap_clear)
1282                 for (i = disks; i--; ) {
1283                         struct r5dev *dev = &sh->dev[i];
1284                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
1285                                 wake_up(&sh->raid_conf->wait_for_overlap);
1286                 }
1287         put_cpu();
1288 }
1289 
1290 #ifdef CONFIG_MULTICORE_RAID456
1291 static void async_run_ops(void *param, async_cookie_t cookie)
1292 {
1293         struct stripe_head *sh = param;
1294         unsigned long ops_request = sh->ops.request;
1295 
1296         clear_bit_unlock(STRIPE_OPS_REQ_PENDING, &sh->state);
1297         wake_up(&sh->ops.wait_for_ops);
1298 
1299         __raid_run_ops(sh, ops_request);
1300         release_stripe(sh);
1301 }
1302 
1303 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1304 {
1305         /* since handle_stripe can be called outside of raid5d context
1306          * we need to ensure sh->ops.request is de-staged before another
1307          * request arrives
1308          */
1309         wait_event(sh->ops.wait_for_ops,
1310                    !test_and_set_bit_lock(STRIPE_OPS_REQ_PENDING, &sh->state));
1311         sh->ops.request = ops_request;
1312 
1313         atomic_inc(&sh->count);
1314         async_schedule(async_run_ops, sh);
1315 }
1316 #else
1317 #define raid_run_ops __raid_run_ops
1318 #endif
1319 
1320 static int grow_one_stripe(raid5_conf_t *conf)
1321 {
1322         struct stripe_head *sh;
1323         sh = kmem_cache_alloc(conf->slab_cache, GFP_KERNEL);
1324         if (!sh)
1325                 return 0;
1326         memset(sh, 0, sizeof(*sh) + (conf->pool_size-1)*sizeof(struct r5dev));
1327         sh->raid_conf = conf;
1328         spin_lock_init(&sh->lock);
1329         #ifdef CONFIG_MULTICORE_RAID456
1330         init_waitqueue_head(&sh->ops.wait_for_ops);
1331         #endif
1332 
1333         if (grow_buffers(sh)) {
1334                 shrink_buffers(sh);
1335                 kmem_cache_free(conf->slab_cache, sh);
1336                 return 0;
1337         }
1338         /* we just created an active stripe so... */
1339         atomic_set(&sh->count, 1);
1340         atomic_inc(&conf->active_stripes);
1341         INIT_LIST_HEAD(&sh->lru);
1342         release_stripe(sh);
1343         return 1;
1344 }
1345 
1346 static int grow_stripes(raid5_conf_t *conf, int num)
1347 {
1348         struct kmem_cache *sc;
1349         int devs = max(conf->raid_disks, conf->previous_raid_disks);
1350 
1351         if (conf->mddev->gendisk)
1352                 sprintf(conf->cache_name[0],
1353                         "raid%d-%s", conf->level, mdname(conf->mddev));
1354         else
1355                 sprintf(conf->cache_name[0],
1356                         "raid%d-%p", conf->level, conf->mddev);
1357         sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
1358 
1359         conf->active_name = 0;
1360         sc = kmem_cache_create(conf->cache_name[conf->active_name],
1361                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
1362                                0, 0, NULL);
1363         if (!sc)
1364                 return 1;
1365         conf->slab_cache = sc;
1366         conf->pool_size = devs;
1367         while (num--)
1368                 if (!grow_one_stripe(conf))
1369                         return 1;
1370         return 0;
1371 }
1372 
1373 /**
1374  * scribble_len - return the required size of the scribble region
1375  * @num - total number of disks in the array
1376  *
1377  * The size must be enough to contain:
1378  * 1/ a struct page pointer for each device in the array +2
1379  * 2/ room to convert each entry in (1) to its corresponding dma
1380  *    (dma_map_page()) or page (page_address()) address.
1381  *
1382  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
1383  * calculate over all devices (not just the data blocks), using zeros in place
1384  * of the P and Q blocks.
1385  */
1386 static size_t scribble_len(int num)
1387 {
1388         size_t len;
1389 
1390         len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
1391 
1392         return len;
1393 }
1394 
1395 static int resize_stripes(raid5_conf_t *conf, int newsize)
1396 {
1397         /* Make all the stripes able to hold 'newsize' devices.
1398          * New slots in each stripe get 'page' set to a new page.
1399          *
1400          * This happens in stages:
1401          * 1/ create a new kmem_cache and allocate the required number of
1402          *    stripe_heads.
1403          * 2/ gather all the old stripe_heads and tranfer the pages across
1404          *    to the new stripe_heads.  This will have the side effect of
1405          *    freezing the array as once all stripe_heads have been collected,
1406          *    no IO will be possible.  Old stripe heads are freed once their
1407          *    pages have been transferred over, and the old kmem_cache is
1408          *    freed when all stripes are done.
1409          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
1410          *    we simple return a failre status - no need to clean anything up.
1411          * 4/ allocate new pages for the new slots in the new stripe_heads.
1412          *    If this fails, we don't bother trying the shrink the
1413          *    stripe_heads down again, we just leave them as they are.
1414          *    As each stripe_head is processed the new one is released into
1415          *    active service.
1416          *
1417          * Once step2 is started, we cannot afford to wait for a write,
1418          * so we use GFP_NOIO allocations.
1419          */
1420         struct stripe_head *osh, *nsh;
1421         LIST_HEAD(newstripes);
1422         struct disk_info *ndisks;
1423         unsigned long cpu;
1424         int err;
1425         struct kmem_cache *sc;
1426         int i;
1427 
1428         if (newsize <= conf->pool_size)
1429                 return 0; /* never bother to shrink */
1430 
1431         err = md_allow_write(conf->mddev);
1432         if (err)
1433                 return err;
1434 
1435         /* Step 1 */
1436         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
1437                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
1438                                0, 0, NULL);
1439         if (!sc)
1440                 return -ENOMEM;
1441 
1442         for (i = conf->max_nr_stripes; i; i--) {
1443                 nsh = kmem_cache_alloc(sc, GFP_KERNEL);
1444                 if (!nsh)
1445                         break;
1446 
1447                 memset(nsh, 0, sizeof(*nsh) + (newsize-1)*sizeof(struct r5dev));
1448 
1449                 nsh->raid_conf = conf;
1450                 spin_lock_init(&nsh->lock);
1451                 #ifdef CONFIG_MULTICORE_RAID456
1452                 init_waitqueue_head(&nsh->ops.wait_for_ops);
1453                 #endif
1454 
1455                 list_add(&nsh->lru, &newstripes);
1456         }
1457         if (i) {
1458                 /* didn't get enough, give up */
1459                 while (!list_empty(&newstripes)) {
1460                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
1461                         list_del(&nsh->lru);
1462                         kmem_cache_free(sc, nsh);
1463                 }
1464                 kmem_cache_destroy(sc);
1465                 return -ENOMEM;
1466         }
1467         /* Step 2 - Must use GFP_NOIO now.
1468          * OK, we have enough stripes, start collecting inactive
1469          * stripes and copying them over
1470          */
1471         list_for_each_entry(nsh, &newstripes, lru) {
1472                 spin_lock_irq(&conf->device_lock);
1473                 wait_event_lock_irq(conf->wait_for_stripe,
1474                                     !list_empty(&conf->inactive_list),
1475                                     conf->device_lock,
1476                                     unplug_slaves(conf->mddev)
1477                         );
1478                 osh = get_free_stripe(conf);
1479                 spin_unlock_irq(&conf->device_lock);
1480                 atomic_set(&nsh->count, 1);
1481                 for(i=0; i<conf->pool_size; i++)
1482                         nsh->dev[i].page = osh->dev[i].page;
1483                 for( ; i<newsize; i++)
1484                         nsh->dev[i].page = NULL;
1485                 kmem_cache_free(conf->slab_cache, osh);
1486         }
1487         kmem_cache_destroy(conf->slab_cache);
1488 
1489         /* Step 3.
1490          * At this point, we are holding all the stripes so the array
1491          * is completely stalled, so now is a good time to resize
1492          * conf->disks and the scribble region
1493          */
1494         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
1495         if (ndisks) {
1496                 for (i=0; i<conf->raid_disks; i++)
1497                         ndisks[i] = conf->disks[i];
1498                 kfree(conf->disks);
1499                 conf->disks = ndisks;
1500         } else
1501                 err = -ENOMEM;
1502 
1503         get_online_cpus();
1504         conf->scribble_len = scribble_len(newsize);
1505         for_each_present_cpu(cpu) {
1506                 struct raid5_percpu *percpu;
1507                 void *scribble;
1508 
1509                 percpu = per_cpu_ptr(conf->percpu, cpu);
1510                 scribble = kmalloc(conf->scribble_len, GFP_NOIO);
1511 
1512                 if (scribble) {
1513                         kfree(percpu->scribble);
1514                         percpu->scribble = scribble;
1515                 } else {
1516                         err = -ENOMEM;
1517                         break;
1518                 }
1519         }
1520         put_online_cpus();
1521 
1522         /* Step 4, return new stripes to service */
1523         while(!list_empty(&newstripes)) {
1524                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
1525                 list_del_init(&nsh->lru);
1526 
1527                 for (i=conf->raid_disks; i < newsize; i++)
1528                         if (nsh->dev[i].page == NULL) {
1529                                 struct page *p = alloc_page(GFP_NOIO);
1530                                 nsh->dev[i].page = p;
1531                                 if (!p)
1532                                         err = -ENOMEM;
1533                         }
1534                 release_stripe(nsh);
1535         }
1536         /* critical section pass, GFP_NOIO no longer needed */
1537 
1538         conf->slab_cache = sc;
1539         conf->active_name = 1-conf->active_name;
1540         conf->pool_size = newsize;
1541         return err;
1542 }
1543 
1544 static int drop_one_stripe(raid5_conf_t *conf)
1545 {
1546         struct stripe_head *sh;
1547 
1548         spin_lock_irq(&conf->device_lock);
1549         sh = get_free_stripe(conf);
1550         spin_unlock_irq(&conf->device_lock);
1551         if (!sh)
1552                 return 0;
1553         BUG_ON(atomic_read(&sh->count));
1554         shrink_buffers(sh);
1555         kmem_cache_free(conf->slab_cache, sh);
1556         atomic_dec(&conf->active_stripes);
1557         return 1;
1558 }
1559 
1560 static void shrink_stripes(raid5_conf_t *conf)
1561 {
1562         while (drop_one_stripe(conf))
1563                 ;
1564 
1565         if (conf->slab_cache)
1566                 kmem_cache_destroy(conf->slab_cache);
1567         conf->slab_cache = NULL;
1568 }
1569 
1570 static void raid5_end_read_request(struct bio * bi, int error)
1571 {
1572         struct stripe_head *sh = bi->bi_private;
1573         raid5_conf_t *conf = sh->raid_conf;
1574         int disks = sh->disks, i;
1575         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1576         char b[BDEVNAME_SIZE];
1577         mdk_rdev_t *rdev;
1578 
1579 
1580         for (i=0 ; i<disks; i++)
1581                 if (bi == &sh->dev[i].req)
1582                         break;
1583 
1584         pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1585                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1586                 uptodate);
1587         if (i == disks) {
1588                 BUG();
1589                 return;
1590         }
1591 
1592         if (uptodate) {
1593                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
1594                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
1595                         rdev = conf->disks[i].rdev;
1596                         printk_rl(KERN_INFO "md/raid:%s: read error corrected"
1597                                   " (%lu sectors at %llu on %s)\n",
1598                                   mdname(conf->mddev), STRIPE_SECTORS,
1599                                   (unsigned long long)(sh->sector
1600                                                        + rdev->data_offset),
1601                                   bdevname(rdev->bdev, b));
1602                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1603                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1604                 }
1605                 if (atomic_read(&conf->disks[i].rdev->read_errors))
1606                         atomic_set(&conf->disks[i].rdev->read_errors, 0);
1607         } else {
1608                 const char *bdn = bdevname(conf->disks[i].rdev->bdev, b);
1609                 int retry = 0;
1610                 rdev = conf->disks[i].rdev;
1611 
1612                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
1613                 atomic_inc(&rdev->read_errors);
1614                 if (conf->mddev->degraded >= conf->max_degraded)
1615                         printk_rl(KERN_WARNING
1616                                   "md/raid:%s: read error not correctable "
1617                                   "(sector %llu on %s).\n",
1618                                   mdname(conf->mddev),
1619                                   (unsigned long long)(sh->sector
1620                                                        + rdev->data_offset),
1621                                   bdn);
1622                 else if (test_bit(R5_ReWrite, &sh->dev[i].flags))
1623                         /* Oh, no!!! */
1624                         printk_rl(KERN_WARNING
1625                                   "md/raid:%s: read error NOT corrected!! "
1626                                   "(sector %llu on %s).\n",
1627                                   mdname(conf->mddev),
1628                                   (unsigned long long)(sh->sector
1629                                                        + rdev->data_offset),
1630                                   bdn);
1631                 else if (atomic_read(&rdev->read_errors)
1632                          > conf->max_nr_stripes)
1633                         printk(KERN_WARNING
1634                                "md/raid:%s: Too many read errors, failing device %s.\n",
1635                                mdname(conf->mddev), bdn);
1636                 else
1637                         retry = 1;
1638                 if (retry)
1639                         set_bit(R5_ReadError, &sh->dev[i].flags);
1640                 else {
1641                         clear_bit(R5_ReadError, &sh->dev[i].flags);
1642                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
1643                         md_error(conf->mddev, rdev);
1644                 }
1645         }
1646         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
1647         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1648         set_bit(STRIPE_HANDLE, &sh->state);
1649         release_stripe(sh);
1650 }
1651 
1652 static void raid5_end_write_request(struct bio *bi, int error)
1653 {
1654         struct stripe_head *sh = bi->bi_private;
1655         raid5_conf_t *conf = sh->raid_conf;
1656         int disks = sh->disks, i;
1657         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1658 
1659         for (i=0 ; i<disks; i++)
1660                 if (bi == &sh->dev[i].req)
1661                         break;
1662 
1663         pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
1664                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1665                 uptodate);
1666         if (i == disks) {
1667                 BUG();
1668                 return;
1669         }
1670 
1671         if (!uptodate)
1672                 md_error(conf->mddev, conf->disks[i].rdev);
1673 
1674         rdev_dec_pending(conf->disks[i].rdev, conf->mddev);
1675         
1676         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1677         set_bit(STRIPE_HANDLE, &sh->state);
1678         release_stripe(sh);
1679 }
1680 
1681 
1682 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous);
1683         
1684 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
1685 {
1686         struct r5dev *dev = &sh->dev[i];
1687 
1688         bio_init(&dev->req);
1689         dev->req.bi_io_vec = &dev->vec;
1690         dev->req.bi_vcnt++;
1691         dev->req.bi_max_vecs++;
1692         dev->vec.bv_page = dev->page;
1693         dev->vec.bv_len = STRIPE_SIZE;
1694         dev->vec.bv_offset = 0;
1695 
1696         dev->req.bi_sector = sh->sector;
1697         dev->req.bi_private = sh;
1698 
1699         dev->flags = 0;
1700         dev->sector = compute_blocknr(sh, i, previous);
1701 }
1702 
1703 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
1704 {
1705         char b[BDEVNAME_SIZE];
1706         raid5_conf_t *conf = mddev->private;
1707         pr_debug("raid456: error called\n");
1708 
1709         if (!test_bit(Faulty, &rdev->flags)) {
1710                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
1711                 if (test_and_clear_bit(In_sync, &rdev->flags)) {
1712                         unsigned long flags;
1713                         spin_lock_irqsave(&conf->device_lock, flags);
1714                         mddev->degraded++;
1715                         spin_unlock_irqrestore(&conf->device_lock, flags);
1716                         /*
1717                          * if recovery was running, make sure it aborts.
1718                          */
1719                         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1720                 }
1721                 set_bit(Faulty, &rdev->flags);
1722                 printk(KERN_ALERT
1723                        "md/raid:%s: Disk failure on %s, disabling device.\n"
1724                        KERN_ALERT
1725                        "md/raid:%s: Operation continuing on %d devices.\n",
1726                        mdname(mddev),
1727                        bdevname(rdev->bdev, b),
1728                        mdname(mddev),
1729                        conf->raid_disks - mddev->degraded);
1730         }
1731 }
1732 
1733 /*
1734  * Input: a 'big' sector number,
1735  * Output: index of the data and parity disk, and the sector # in them.
1736  */
1737 static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
1738                                      int previous, int *dd_idx,
1739                                      struct stripe_head *sh)
1740 {
1741         sector_t stripe, stripe2;
1742         sector_t chunk_number;
1743         unsigned int chunk_offset;
1744         int pd_idx, qd_idx;
1745         int ddf_layout = 0;
1746         sector_t new_sector;
1747         int algorithm = previous ? conf->prev_algo
1748                                  : conf->algorithm;
1749         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
1750                                          : conf->chunk_sectors;
1751         int raid_disks = previous ? conf->previous_raid_disks
1752                                   : conf->raid_disks;
1753         int data_disks = raid_disks - conf->max_degraded;
1754 
1755         /* First compute the information on this sector */
1756 
1757         /*
1758          * Compute the chunk number and the sector offset inside the chunk
1759          */
1760         chunk_offset = sector_div(r_sector, sectors_per_chunk);
1761         chunk_number = r_sector;
1762 
1763         /*
1764          * Compute the stripe number
1765          */
1766         stripe = chunk_number;
1767         *dd_idx = sector_div(stripe, data_disks);
1768         stripe2 = stripe;
1769         /*
1770          * Select the parity disk based on the user selected algorithm.
1771          */
1772         pd_idx = qd_idx = ~0;
1773         switch(conf->level) {
1774         case 4:
1775                 pd_idx = data_disks;
1776                 break;
1777         case 5:
1778                 switch (algorithm) {
1779                 case ALGORITHM_LEFT_ASYMMETRIC:
1780                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
1781                         if (*dd_idx >= pd_idx)
1782                                 (*dd_idx)++;
1783                         break;
1784                 case ALGORITHM_RIGHT_ASYMMETRIC:
1785                         pd_idx = sector_div(stripe2, raid_disks);
1786                         if (*dd_idx >= pd_idx)
1787                                 (*dd_idx)++;
1788                         break;
1789                 case ALGORITHM_LEFT_SYMMETRIC:
1790                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
1791                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
1792                         break;
1793                 case ALGORITHM_RIGHT_SYMMETRIC:
1794                         pd_idx = sector_div(stripe2, raid_disks);
1795                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
1796                         break;
1797                 case ALGORITHM_PARITY_0:
1798                         pd_idx = 0;
1799                         (*dd_idx)++;
1800                         break;
1801                 case ALGORITHM_PARITY_N:
1802                         pd_idx = data_disks;
1803                         break;
1804                 default:
1805                         BUG();
1806                 }
1807                 break;
1808         case 6:
1809 
1810                 switch (algorithm) {
1811                 case ALGORITHM_LEFT_ASYMMETRIC:
1812                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
1813                         qd_idx = pd_idx + 1;
1814                         if (pd_idx == raid_disks-1) {
1815                                 (*dd_idx)++;    /* Q D D D P */
1816                                 qd_idx = 0;
1817                         } else if (*dd_idx >= pd_idx)
1818                                 (*dd_idx) += 2; /* D D P Q D */
1819                         break;
1820                 case ALGORITHM_RIGHT_ASYMMETRIC:
1821                         pd_idx = sector_div(stripe2, raid_disks);
1822                         qd_idx = pd_idx + 1;
1823                         if (pd_idx == raid_disks-1) {
1824                                 (*dd_idx)++;    /* Q D D D P */
1825                                 qd_idx = 0;
1826                         } else if (*dd_idx >= pd_idx)
1827                                 (*dd_idx) += 2; /* D D P Q D */
1828                         break;
1829                 case ALGORITHM_LEFT_SYMMETRIC:
1830                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
1831                         qd_idx = (pd_idx + 1) % raid_disks;
1832                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
1833                         break;
1834                 case ALGORITHM_RIGHT_SYMMETRIC:
1835                         pd_idx = sector_div(stripe2, raid_disks);
1836                         qd_idx = (pd_idx + 1) % raid_disks;
1837                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
1838                         break;
1839 
1840                 case ALGORITHM_PARITY_0:
1841                         pd_idx = 0;
1842                         qd_idx = 1;
1843                         (*dd_idx) += 2;
1844                         break;
1845                 case ALGORITHM_PARITY_N:
1846                         pd_idx = data_disks;
1847                         qd_idx = data_disks + 1;
1848                         break;
1849 
1850                 case ALGORITHM_ROTATING_ZERO_RESTART:
1851                         /* Exactly the same as RIGHT_ASYMMETRIC, but or
1852                          * of blocks for computing Q is different.
1853                          */
1854                         pd_idx = sector_div(stripe2, raid_disks);
1855                         qd_idx = pd_idx + 1;
1856                         if (pd_idx == raid_disks-1) {
1857                                 (*dd_idx)++;    /* Q D D D P */
1858                                 qd_idx = 0;
1859                         } else if (*dd_idx >= pd_idx)
1860                                 (*dd_idx) += 2; /* D D P Q D */
1861                         ddf_layout = 1;
1862                         break;
1863 
1864                 case ALGORITHM_ROTATING_N_RESTART:
1865                         /* Same a left_asymmetric, by first stripe is
1866                          * D D D P Q  rather than
1867                          * Q D D D P
1868                          */
1869                         stripe2 += 1;
1870                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
1871                         qd_idx = pd_idx + 1;
1872                         if (pd_idx == raid_disks-1) {
1873                                 (*dd_idx)++;    /* Q D D D P */
1874                                 qd_idx = 0;
1875                         } else if (*dd_idx >= pd_idx)
1876                                 (*dd_idx) += 2; /* D D P Q D */
1877                         ddf_layout = 1;
1878                         break;
1879 
1880                 case ALGORITHM_ROTATING_N_CONTINUE:
1881                         /* Same as left_symmetric but Q is before P */
1882                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
1883                         qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
1884                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
1885                         ddf_layout = 1;
1886                         break;
1887 
1888                 case ALGORITHM_LEFT_ASYMMETRIC_6:
1889                         /* RAID5 left_asymmetric, with Q on last device */
1890                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
1891                         if (*dd_idx >= pd_idx)
1892                                 (*dd_idx)++;
1893                         qd_idx = raid_disks - 1;
1894                         break;
1895 
1896                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
1897                         pd_idx = sector_div(stripe2, raid_disks-1);
1898                         if (*dd_idx >= pd_idx)
1899                                 (*dd_idx)++;
1900                         qd_idx = raid_disks - 1;
1901                         break;
1902 
1903                 case ALGORITHM_LEFT_SYMMETRIC_6:
1904                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
1905                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
1906                         qd_idx = raid_disks - 1;
1907                         break;
1908 
1909                 case ALGORITHM_RIGHT_SYMMETRIC_6:
1910                         pd_idx = sector_div(stripe2, raid_disks-1);
1911                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
1912                         qd_idx = raid_disks - 1;
1913                         break;
1914 
1915                 case ALGORITHM_PARITY_0_6:
1916                         pd_idx = 0;
1917                         (*dd_idx)++;
1918                         qd_idx = raid_disks - 1;
1919                         break;
1920 
1921                 default:
1922                         BUG();
1923                 }
1924                 break;
1925         }
1926 
1927         if (sh) {
1928                 sh->pd_idx = pd_idx;
1929                 sh->qd_idx = qd_idx;
1930                 sh->ddf_layout = ddf_layout;
1931         }
1932         /*
1933          * Finally, compute the new sector number
1934          */
1935         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
1936         return new_sector;
1937 }
1938 
1939 
1940 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
1941 {
1942         raid5_conf_t *conf = sh->raid_conf;
1943         int raid_disks = sh->disks;
1944         int data_disks = raid_disks - conf->max_degraded;
1945         sector_t new_sector = sh->sector, check;
1946         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
1947                                          : conf->chunk_sectors;
1948         int algorithm = previous ? conf->prev_algo
1949                                  : conf->algorithm;
1950         sector_t stripe;
1951         int chunk_offset;
1952         sector_t chunk_number;
1953         int dummy1, dd_idx = i;
1954         sector_t r_sector;
1955         struct stripe_head sh2;
1956 
1957 
1958         chunk_offset = sector_div(new_sector, sectors_per_chunk);
1959         stripe = new_sector;
1960 
1961         if (i == sh->pd_idx)
1962                 return 0;
1963         switch(conf->level) {
1964         case 4: break;
1965         case 5:
1966                 switch (algorithm) {
1967                 case ALGORITHM_LEFT_ASYMMETRIC:
1968                 case ALGORITHM_RIGHT_ASYMMETRIC:
1969                         if (i > sh->pd_idx)
1970                                 i--;
1971                         break;
1972                 case ALGORITHM_LEFT_SYMMETRIC:
1973                 case ALGORITHM_RIGHT_SYMMETRIC:
1974                         if (i < sh->pd_idx)
1975                                 i += raid_disks;
1976                         i -= (sh->pd_idx + 1);
1977                         break;
1978                 case ALGORITHM_PARITY_0:
1979                         i -= 1;
1980                         break;
1981                 case ALGORITHM_PARITY_N:
1982                         break;
1983                 default:
1984                         BUG();
1985                 }
1986                 break;
1987         case 6:
1988                 if (i == sh->qd_idx)
1989                         return 0; /* It is the Q disk */
1990                 switch (algorithm) {
1991                 case ALGORITHM_LEFT_ASYMMETRIC:
1992                 case ALGORITHM_RIGHT_ASYMMETRIC:
1993                 case ALGORITHM_ROTATING_ZERO_RESTART:
1994                 case ALGORITHM_ROTATING_N_RESTART:
1995                         if (sh->pd_idx == raid_disks-1)
1996                                 i--;    /* Q D D D P */
1997                         else if (i > sh->pd_idx)
1998                                 i -= 2; /* D D P Q D */
1999                         break;
2000                 case ALGORITHM_LEFT_SYMMETRIC:
2001                 case ALGORITHM_RIGHT_SYMMETRIC:
2002                         if (sh->pd_idx == raid_disks-1)
2003                                 i--; /* Q D D D P */
2004                         else {
2005                                 /* D D P Q D */
2006                                 if (i < sh->pd_idx)
2007                                         i += raid_disks;
2008                                 i -= (sh->pd_idx + 2);
2009                         }
2010                         break;
2011                 case ALGORITHM_PARITY_0:
2012                         i -= 2;
2013                         break;
2014                 case ALGORITHM_PARITY_N:
2015                         break;
2016                 case ALGORITHM_ROTATING_N_CONTINUE:
2017                         /* Like left_symmetric, but P is before Q */
2018                         if (sh->pd_idx == 0)
2019                                 i--;    /* P D D D Q */
2020                         else {
2021                                 /* D D Q P D */
2022                                 if (i < sh->pd_idx)
2023                                         i += raid_disks;
2024                                 i -= (sh->pd_idx + 1);
2025                         }
2026                         break;
2027                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2028                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2029                         if (i > sh->pd_idx)
2030                                 i--;
2031                         break;
2032                 case ALGORITHM_LEFT_SYMMETRIC_6:
2033                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2034                         if (i < sh->pd_idx)
2035                                 i += data_disks + 1;
2036                         i -= (sh->pd_idx + 1);
2037                         break;
2038                 case ALGORITHM_PARITY_0_6:
2039                         i -= 1;
2040                         break;
2041                 default:
2042                         BUG();
2043                 }
2044                 break;
2045         }
2046 
2047         chunk_number = stripe * data_disks + i;
2048         r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2049 
2050         check = raid5_compute_sector(conf, r_sector,
2051                                      previous, &dummy1, &sh2);
2052         if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2053                 || sh2.qd_idx != sh->qd_idx) {
2054                 printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
2055                        mdname(conf->mddev));
2056                 return 0;
2057         }
2058         return r_sector;
2059 }
2060 
2061 
2062 static void
2063 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2064                          int rcw, int expand)
2065 {
2066         int i, pd_idx = sh->pd_idx, disks = sh->disks;
2067         raid5_conf_t *conf = sh->raid_conf;
2068         int level = conf->level;
2069 
2070         if (rcw) {
2071                 /* if we are not expanding this is a proper write request, and
2072                  * there will be bios with new data to be drained into the
2073                  * stripe cache
2074                  */
2075                 if (!expand) {
2076                         sh->reconstruct_state = reconstruct_state_drain_run;
2077                         set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2078                 } else
2079                         sh->reconstruct_state = reconstruct_state_run;
2080 
2081                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2082 
2083                 for (i = disks; i--; ) {
2084                         struct r5dev *dev = &sh->dev[i];
2085 
2086                         if (dev->towrite) {
2087                                 set_bit(R5_LOCKED, &dev->flags);
2088                                 set_bit(R5_Wantdrain, &dev->flags);
2089                                 if (!expand)
2090                                         clear_bit(R5_UPTODATE, &dev->flags);
2091                                 s->locked++;
2092                         }
2093                 }
2094                 if (s->locked + conf->max_degraded == disks)
2095                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2096                                 atomic_inc(&conf->pending_full_writes);
2097         } else {
2098                 BUG_ON(level == 6);
2099                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2100                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2101 
2102                 sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2103                 set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2104                 set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2105                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2106 
2107                 for (i = disks; i--; ) {
2108                         struct r5dev *dev = &sh->dev[i];
2109                         if (i == pd_idx)
2110                                 continue;
2111 
2112                         if (dev->towrite &&
2113                             (test_bit(R5_UPTODATE, &dev->flags) ||
2114                              test_bit(R5_Wantcompute, &dev->flags))) {
2115                                 set_bit(R5_Wantdrain, &dev->flags);
2116                                 set_bit(R5_LOCKED, &dev->flags);
2117                                 clear_bit(R5_UPTODATE, &dev->flags);
2118                                 s->locked++;
2119                         }
2120                 }
2121         }
2122 
2123         /* keep the parity disk(s) locked while asynchronous operations
2124          * are in flight
2125          */
2126         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2127         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2128         s->locked++;
2129 
2130         if (level == 6) {
2131                 int qd_idx = sh->qd_idx;
2132                 struct r5dev *dev = &sh->dev[qd_idx];
2133 
2134                 set_bit(R5_LOCKED, &dev->flags);
2135                 clear_bit(R5_UPTODATE, &dev->flags);
2136                 s->locked++;
2137         }
2138 
2139         pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2140                 __func__, (unsigned long long)sh->sector,
2141                 s->locked, s->ops_request);
2142 }
2143 
2144 /*
2145  * Each stripe/dev can have one or more bion attached.
2146  * toread/towrite point to the first in a chain.
2147  * The bi_next chain must be in order.
2148  */
2149 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
2150 {
2151         struct bio **bip;
2152         raid5_conf_t *conf = sh->raid_conf;
2153         int firstwrite=0;
2154 
2155         pr_debug("adding bh b#%llu to stripe s#%llu\n",
2156                 (unsigned long long)bi->bi_sector,
2157                 (unsigned long long)sh->sector);
2158 
2159 
2160         spin_lock(&sh->lock);
2161         spin_lock_irq(&conf->device_lock);
2162         if (forwrite) {
2163                 bip = &sh->dev[dd_idx].towrite;
2164                 if (*bip == NULL && sh->dev[dd_idx].written == NULL)
2165                         firstwrite = 1;
2166         } else
2167                 bip = &sh->dev[dd_idx].toread;
2168         while (*bip && (*bip)->bi_sector < bi->bi_sector) {
2169                 if ((*bip)->bi_sector + ((*bip)->bi_size >> 9) > bi->bi_sector)
2170                         goto overlap;
2171                 bip = & (*bip)->bi_next;
2172         }
2173         if (*bip && (*bip)->bi_sector < bi->bi_sector + ((bi->bi_size)>>9))
2174                 goto overlap;
2175 
2176         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
2177         if (*bip)
2178                 bi->bi_next = *bip;
2179         *bip = bi;
2180         bi->bi_phys_segments++;
2181         spin_unlock_irq(&conf->device_lock);
2182         spin_unlock(&sh->lock);
2183 
2184         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
2185                 (unsigned long long)bi->bi_sector,
2186                 (unsigned long long)sh->sector, dd_idx);
2187 
2188         if (conf->mddev->bitmap && firstwrite) {
2189                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
2190                                   STRIPE_SECTORS, 0);
2191                 sh->bm_seq = conf->seq_flush+1;
2192                 set_bit(STRIPE_BIT_DELAY, &sh->state);
2193         }
2194 
2195         if (forwrite) {
2196                 /* check if page is covered */
2197                 sector_t sector = sh->dev[dd_idx].sector;
2198                 for (bi=sh->dev[dd_idx].towrite;
2199                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
2200                              bi && bi->bi_sector <= sector;
2201                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
2202                         if (bi->bi_sector + (bi->bi_size>>9) >= sector)
2203                                 sector = bi->bi_sector + (bi->bi_size>>9);
2204                 }
2205                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
2206                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
2207         }
2208         return 1;
2209 
2210  overlap:
2211         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
2212         spin_unlock_irq(&conf->device_lock);
2213         spin_unlock(&sh->lock);
2214         return 0;
2215 }
2216 
2217 static void end_reshape(raid5_conf_t *conf);
2218 
2219 static void stripe_set_idx(sector_t stripe, raid5_conf_t *conf, int previous,
2220                             struct stripe_head *sh)
2221 {
2222         int sectors_per_chunk =
2223                 previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
2224         int dd_idx;
2225         int chunk_offset = sector_div(stripe, sectors_per_chunk);
2226         int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
2227 
2228         raid5_compute_sector(conf,
2229                              stripe * (disks - conf->max_degraded)
2230                              *sectors_per_chunk + chunk_offset,
2231                              previous,
2232                              &dd_idx, sh);
2233 }
2234 
2235 static void
2236 handle_failed_stripe(raid5_conf_t *conf, struct stripe_head *sh,
2237                                 struct stripe_head_state *s, int disks,
2238                                 struct bio **return_bi)
2239 {
2240         int i;
2241         for (i = disks; i--; ) {
2242                 struct bio *bi;
2243                 int bitmap_end = 0;
2244 
2245                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2246                         mdk_rdev_t *rdev;
2247                         rcu_read_lock();
2248                         rdev = rcu_dereference(conf->disks[i].rdev);
2249                         if (rdev && test_bit(In_sync, &rdev->flags))
2250                                 /* multiple read failures in one stripe */
2251                                 md_error(conf->mddev, rdev);
2252                         rcu_read_unlock();
2253                 }
2254                 spin_lock_irq(&conf->device_lock);
2255                 /* fail all writes first */
2256                 bi = sh->dev[i].towrite;
2257                 sh->dev[i].towrite = NULL;
2258                 if (bi) {
2259                         s->to_write--;
2260                         bitmap_end = 1;
2261                 }
2262 
2263                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2264                         wake_up(&conf->wait_for_overlap);
2265 
2266                 while (bi && bi->bi_sector <
2267                         sh->dev[i].sector + STRIPE_SECTORS) {
2268                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2269                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2270                         if (!raid5_dec_bi_phys_segments(bi)) {
2271                                 md_write_end(conf->mddev);
2272                                 bi->bi_next = *return_bi;
2273                                 *return_bi = bi;
2274                         }
2275                         bi = nextbi;
2276                 }
2277                 /* and fail all 'written' */
2278                 bi = sh->dev[i].written;
2279                 sh->dev[i].written = NULL;
2280                 if (bi) bitmap_end = 1;
2281                 while (bi && bi->bi_sector <
2282                        sh->dev[i].sector + STRIPE_SECTORS) {
2283                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
2284                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2285                         if (!raid5_dec_bi_phys_segments(bi)) {
2286                                 md_write_end(conf->mddev);
2287                                 bi->bi_next = *return_bi;
2288                                 *return_bi = bi;
2289                         }
2290                         bi = bi2;
2291                 }
2292 
2293                 /* fail any reads if this device is non-operational and
2294                  * the data has not reached the cache yet.
2295                  */
2296                 if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
2297                     (!test_bit(R5_Insync, &sh->dev[i].flags) ||
2298                       test_bit(R5_ReadError, &sh->dev[i].flags))) {
2299                         bi = sh->dev[i].toread;
2300                         sh->dev[i].toread = NULL;
2301                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2302                                 wake_up(&conf->wait_for_overlap);
2303                         if (bi) s->to_read--;
2304                         while (bi && bi->bi_sector <
2305                                sh->dev[i].sector + STRIPE_SECTORS) {
2306                                 struct bio *nextbi =
2307                                         r5_next_bio(bi, sh->dev[i].sector);
2308                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
2309                                 if (!raid5_dec_bi_phys_segments(bi)) {
2310                                         bi->bi_next = *return_bi;
2311                                         *return_bi = bi;
2312                                 }
2313                                 bi = nextbi;
2314                         }
2315                 }
2316                 spin_unlock_irq(&conf->device_lock);
2317                 if (bitmap_end)
2318                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2319                                         STRIPE_SECTORS, 0, 0);
2320         }
2321 
2322         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2323                 if (atomic_dec_and_test(&conf->pending_full_writes))
2324                         md_wakeup_thread(conf->mddev->thread);
2325 }
2326 
2327 /* fetch_block5 - checks the given member device to see if its data needs
2328  * to be read or computed to satisfy a request.
2329  *
2330  * Returns 1 when no more member devices need to be checked, otherwise returns
2331  * 0 to tell the loop in handle_stripe_fill5 to continue
2332  */
2333 static int fetch_block5(struct stripe_head *sh, struct stripe_head_state *s,
2334                         int disk_idx, int disks)
2335 {
2336         struct r5dev *dev = &sh->dev[disk_idx];
2337         struct r5dev *failed_dev = &sh->dev[s->failed_num];
2338 
2339         /* is the data in this block needed, and can we get it? */
2340         if (!test_bit(R5_LOCKED, &dev->flags) &&
2341             !test_bit(R5_UPTODATE, &dev->flags) &&
2342             (dev->toread ||
2343              (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
2344              s->syncing || s->expanding ||
2345              (s->failed &&
2346               (failed_dev->toread ||
2347                (failed_dev->towrite &&
2348                 !test_bit(R5_OVERWRITE, &failed_dev->flags)))))) {
2349                 /* We would like to get this block, possibly by computing it,
2350                  * otherwise read it if the backing disk is insync
2351                  */
2352                 if ((s->uptodate == disks - 1) &&
2353                     (s->failed && disk_idx == s->failed_num)) {
2354                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2355                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2356                         set_bit(R5_Wantcompute, &dev->flags);
2357                         sh->ops.target = disk_idx;
2358                         sh->ops.target2 = -1;
2359                         s->req_compute = 1;
2360                         /* Careful: from this point on 'uptodate' is in the eye
2361                          * of raid_run_ops which services 'compute' operations
2362                          * before writes. R5_Wantcompute flags a block that will
2363                          * be R5_UPTODATE by the time it is needed for a
2364                          * subsequent operation.
2365                          */
2366                         s->uptodate++;
2367                         return 1; /* uptodate + compute == disks */
2368                 } else if (test_bit(R5_Insync, &dev->flags)) {
2369                         set_bit(R5_LOCKED, &dev->flags);
2370                         set_bit(R5_Wantread, &dev->flags);
2371                         s->locked++;
2372                         pr_debug("Reading block %d (sync=%d)\n", disk_idx,
2373                                 s->syncing);
2374                 }
2375         }
2376 
2377         return 0;
2378 }
2379 
2380 /**
2381  * handle_stripe_fill5 - read or compute data to satisfy pending requests.
2382  */
2383 static void handle_stripe_fill5(struct stripe_head *sh,
2384                         struct stripe_head_state *s, int disks)
2385 {
2386         int i;
2387 
2388         /* look for blocks to read/compute, skip this if a compute
2389          * is already in flight, or if the stripe contents are in the
2390          * midst of changing due to a write
2391          */
2392         if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
2393             !sh->reconstruct_state)
2394                 for (i = disks; i--; )
2395                         if (fetch_block5(sh, s, i, disks))
2396                                 break;
2397         set_bit(STRIPE_HANDLE, &sh->state);
2398 }
2399 
2400 /* fetch_block6 - checks the given member device to see if its data needs
2401  * to be read or computed to satisfy a request.
2402  *
2403  * Returns 1 when no more member devices need to be checked, otherwise returns
2404  * 0 to tell the loop in handle_stripe_fill6 to continue
2405  */
2406 static int fetch_block6(struct stripe_head *sh, struct stripe_head_state *s,
2407                          struct r6_state *r6s, int disk_idx, int disks)
2408 {
2409         struct r5dev *dev = &sh->dev[disk_idx];
2410         struct r5dev *fdev[2] = { &sh->dev[r6s->failed_num[0]],
2411                                   &sh->dev[r6s->failed_num[1]] };
2412 
2413         if (!test_bit(R5_LOCKED, &dev->flags) &&
2414             !test_bit(R5_UPTODATE, &dev->flags) &&
2415             (dev->toread ||
2416              (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
2417              s->syncing || s->expanding ||
2418              (s->failed >= 1 &&
2419               (fdev[0]->toread || s->to_write)) ||
2420              (s->failed >= 2 &&
2421               (fdev[1]->toread || s->to_write)))) {
2422                 /* we would like to get this block, possibly by computing it,
2423                  * otherwise read it if the backing disk is insync
2424                  */
2425                 BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
2426                 BUG_ON(test_bit(R5_Wantread, &dev->flags));
2427                 if ((s->uptodate == disks - 1) &&
2428                     (s->failed && (disk_idx == r6s->failed_num[0] ||
2429                                    disk_idx == r6s->failed_num[1]))) {
2430                         /* have disk failed, and we're requested to fetch it;
2431                          * do compute it
2432                          */
2433                         pr_debug("Computing stripe %llu block %d\n",
2434                                (unsigned long long)sh->sector, disk_idx);
2435                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2436                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2437                         set_bit(R5_Wantcompute, &dev->flags);
2438                         sh->ops.target = disk_idx;
2439                         sh->ops.target2 = -1; /* no 2nd target */
2440                         s->req_compute = 1;
2441                         s->uptodate++;
2442                         return 1;
2443                 } else if (s->uptodate == disks-2 && s->failed >= 2) {
2444                         /* Computing 2-failure is *very* expensive; only
2445                          * do it if failed >= 2
2446                          */
2447                         int other;
2448                         for (other = disks; other--; ) {
2449                                 if (other == disk_idx)
2450                                         continue;
2451                                 if (!test_bit(R5_UPTODATE,
2452                                       &sh->dev[other].flags))
2453                                         break;
2454                         }
2455                         BUG_ON(other < 0);
2456                         pr_debug("Computing stripe %llu blocks %d,%d\n",
2457                                (unsigned long long)sh->sector,
2458                                disk_idx, other);
2459                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2460                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2461                         set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
2462                         set_bit(R5_Wantcompute, &sh->dev[other].flags);
2463                         sh->ops.target = disk_idx;
2464                         sh->ops.target2 = other;
2465                         s->uptodate += 2;
2466                         s->req_compute = 1;
2467                         return 1;
2468                 } else if (test_bit(R5_Insync, &dev->flags)) {
2469                         set_bit(R5_LOCKED, &dev->flags);
2470                         set_bit(R5_Wantread, &dev->flags);
2471                         s->locked++;
2472                         pr_debug("Reading block %d (sync=%d)\n",
2473                                 disk_idx, s->syncing);
2474                 }
2475         }
2476 
2477         return 0;
2478 }
2479 
2480 /**
2481  * handle_stripe_fill6 - read or compute data to satisfy pending requests.
2482  */
2483 static void handle_stripe_fill6(struct stripe_head *sh,
2484                         struct stripe_head_state *s, struct r6_state *r6s,
2485                         int disks)
2486 {
2487         int i;
2488 
2489         /* look for blocks to read/compute, skip this if a compute
2490          * is already in flight, or if the stripe contents are in the
2491          * midst of changing due to a write
2492          */
2493         if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
2494             !sh->reconstruct_state)
2495                 for (i = disks; i--; )
2496                         if (fetch_block6(sh, s, r6s, i, disks))
2497                                 break;
2498         set_bit(STRIPE_HANDLE, &sh->state);
2499 }
2500 
2501 
2502 /* handle_stripe_clean_event
2503  * any written block on an uptodate or failed drive can be returned.
2504  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
2505  * never LOCKED, so we don't need to test 'failed' directly.
2506  */
2507 static void handle_stripe_clean_event(raid5_conf_t *conf,
2508         struct stripe_head *sh, int disks, struct bio **return_bi)
2509 {
2510         int i;
2511         struct r5dev *dev;
2512 
2513         for (i = disks; i--; )
2514                 if (sh->dev[i].written) {
2515                         dev = &sh->dev[i];
2516                         if (!test_bit(R5_LOCKED, &dev->flags) &&
2517                                 test_bit(R5_UPTODATE, &dev->flags)) {
2518                                 /* We can return any write requests */
2519                                 struct bio *wbi, *wbi2;
2520                                 int bitmap_end = 0;
2521                                 pr_debug("Return write for disc %d\n", i);
2522                                 spin_lock_irq(&conf->device_lock);
2523                                 wbi = dev->written;
2524                                 dev->written = NULL;
2525                                 while (wbi && wbi->bi_sector <
2526                                         dev->sector + STRIPE_SECTORS) {
2527                                         wbi2 = r5_next_bio(wbi, dev->sector);
2528                                         if (!raid5_dec_bi_phys_segments(wbi)) {
2529                                                 md_write_end(conf->mddev);
2530                                                 wbi->bi_next = *return_bi;
2531                                                 *return_bi = wbi;
2532                                         }
2533                                         wbi = wbi2;
2534                                 }
2535                                 if (dev->towrite == NULL)
2536                                         bitmap_end = 1;
2537                                 spin_unlock_irq(&conf->device_lock);
2538                                 if (bitmap_end)
2539                                         bitmap_endwrite(conf->mddev->bitmap,
2540                                                         sh->sector,
2541                                                         STRIPE_SECTORS,
2542                                          !test_bit(STRIPE_DEGRADED, &sh->state),
2543                                                         0);
2544                         }
2545                 }
2546 
2547         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2548                 if (atomic_dec_and_test(&conf->pending_full_writes))
2549                         md_wakeup_thread(conf->mddev->thread);
2550 }
2551 
2552 static void handle_stripe_dirtying5(raid5_conf_t *conf,
2553                 struct stripe_head *sh, struct stripe_head_state *s, int disks)
2554 {
2555         int rmw = 0, rcw = 0, i;
2556         for (i = disks; i--; ) {
2557                 /* would I have to read this buffer for read_modify_write */
2558                 struct r5dev *dev = &sh->dev[i];
2559                 if ((dev->towrite || i == sh->pd_idx) &&
2560                     !test_bit(R5_LOCKED, &dev->flags) &&
2561                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2562                       test_bit(R5_Wantcompute, &dev->flags))) {
2563                         if (test_bit(R5_Insync, &dev->flags))
2564                                 rmw++;
2565                         else
2566                                 rmw += 2*disks;  /* cannot read it */
2567                 }
2568                 /* Would I have to read this buffer for reconstruct_write */
2569                 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
2570                     !test_bit(R5_LOCKED, &dev->flags) &&
2571                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2572                     test_bit(R5_Wantcompute, &dev->flags))) {
2573                         if (test_bit(R5_Insync, &dev->flags)) rcw++;
2574                         else
2575                                 rcw += 2*disks;
2576                 }
2577         }
2578         pr_debug("for sector %llu, rmw=%d rcw=%d\n",
2579                 (unsigned long long)sh->sector, rmw, rcw);
2580         set_bit(STRIPE_HANDLE, &sh->state);
2581         if (rmw < rcw && rmw > 0)
2582                 /* prefer read-modify-write, but need to get some data */
2583                 for (i = disks; i--; ) {
2584                         struct r5dev *dev = &sh->dev[i];
2585                         if ((dev->towrite || i == sh->pd_idx) &&
2586                             !test_bit(R5_LOCKED, &dev->flags) &&
2587                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2588                             test_bit(R5_Wantcompute, &dev->flags)) &&
2589                             test_bit(R5_Insync, &dev->flags)) {
2590                                 if (
2591                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2592                                         pr_debug("Read_old block "
2593                                                 "%d for r-m-w\n", i);
2594                                         set_bit(R5_LOCKED, &dev->flags);
2595                                         set_bit(R5_Wantread, &dev->flags);
2596                                         s->locked++;
2597                                 } else {
2598                                         set_bit(STRIPE_DELAYED, &sh->state);
2599                                         set_bit(STRIPE_HANDLE, &sh->state);
2600                                 }
2601                         }
2602                 }
2603         if (rcw <= rmw && rcw > 0)
2604                 /* want reconstruct write, but need to get some data */
2605                 for (i = disks; i--; ) {
2606                         struct r5dev *dev = &sh->dev[i];
2607                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2608                             i != sh->pd_idx &&
2609                             !test_bit(R5_LOCKED, &dev->flags) &&
2610                             !(test_bit(R5_UPTODATE, &dev->flags) ||
2611                             test_bit(R5_Wantcompute, &dev->flags)) &&
2612                             test_bit(R5_Insync, &dev->flags)) {
2613                                 if (
2614                                   test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2615                                         pr_debug("Read_old block "
2616                                                 "%d for Reconstruct\n", i);
2617                                         set_bit(R5_LOCKED, &dev->flags);
2618                                         set_bit(R5_Wantread, &dev->flags);
2619                                         s->locked++;
2620                                 } else {
2621                                         set_bit(STRIPE_DELAYED, &sh->state);
2622                                         set_bit(STRIPE_HANDLE, &sh->state);
2623                                 }
2624                         }
2625                 }
2626         /* now if nothing is locked, and if we have enough data,
2627          * we can start a write request
2628          */
2629         /* since handle_stripe can be called at any time we need to handle the
2630          * case where a compute block operation has been submitted and then a
2631          * subsequent call wants to start a write request.  raid_run_ops only
2632          * handles the case where compute block and reconstruct are requested
2633          * simultaneously.  If this is not the case then new writes need to be
2634          * held off until the compute completes.
2635          */
2636         if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
2637             (s->locked == 0 && (rcw == 0 || rmw == 0) &&
2638             !test_bit(STRIPE_BIT_DELAY, &sh->state)))
2639                 schedule_reconstruction(sh, s, rcw == 0, 0);
2640 }
2641 
2642 static void handle_stripe_dirtying6(raid5_conf_t *conf,
2643                 struct stripe_head *sh, struct stripe_head_state *s,
2644                 struct r6_state *r6s, int disks)
2645 {
2646         int rcw = 0, pd_idx = sh->pd_idx, i;
2647         int qd_idx = sh->qd_idx;
2648 
2649         set_bit(STRIPE_HANDLE, &sh->state);
2650         for (i = disks; i--; ) {
2651                 struct r5dev *dev = &sh->dev[i];
2652                 /* check if we haven't enough data */
2653                 if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2654                     i != pd_idx && i != qd_idx &&
2655                     !test_bit(R5_LOCKED, &dev->flags) &&
2656                     !(test_bit(R5_UPTODATE, &dev->flags) ||
2657                       test_bit(R5_Wantcompute, &dev->flags))) {
2658                         rcw++;
2659                         if (!test_bit(R5_Insync, &dev->flags))
2660                                 continue; /* it's a failed drive */
2661 
2662                         if (
2663                           test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
2664                                 pr_debug("Read_old stripe %llu "
2665                                         "block %d for Reconstruct\n",
2666                                      (unsigned long long)sh->sector, i);
2667                                 set_bit(R5_LOCKED, &dev->flags);
2668                                 set_bit(R5_Wantread, &dev->flags);
2669                                 s->locked++;
2670                         } else {
2671                                 pr_debug("Request delayed stripe %llu "
2672                                         "block %d for Reconstruct\n",
2673                                      (unsigned long long)sh->sector, i);
2674                                 set_bit(STRIPE_DELAYED, &sh->state);
2675                                 set_bit(STRIPE_HANDLE, &sh->state);
2676                         }
2677                 }
2678         }
2679         /* now if nothing is locked, and if we have enough data, we can start a
2680          * write request
2681          */
2682         if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
2683             s->locked == 0 && rcw == 0 &&
2684             !test_bit(STRIPE_BIT_DELAY, &sh->state)) {
2685                 schedule_reconstruction(sh, s, 1, 0);
2686         }
2687 }
2688 
2689 static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
2690                                 struct stripe_head_state *s, int disks)
2691 {
2692         struct r5dev *dev = NULL;
2693 
2694         set_bit(STRIPE_HANDLE, &sh->state);
2695 
2696         switch (sh->check_state) {
2697         case check_state_idle:
2698                 /* start a new check operation if there are no failures */
2699                 if (s->failed == 0) {
2700                         BUG_ON(s->uptodate != disks);
2701                         sh->check_state = check_state_run;
2702                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
2703                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
2704                         s->uptodate--;
2705                         break;
2706                 }
2707                 dev = &sh->dev[s->failed_num];
2708                 /* fall through */
2709         case check_state_compute_result:
2710                 sh->check_state = check_state_idle;
2711                 if (!dev)
2712                         dev = &sh->dev[sh->pd_idx];
2713 
2714                 /* check that a write has not made the stripe insync */
2715                 if (test_bit(STRIPE_INSYNC, &sh->state))
2716                         break;
2717 
2718                 /* either failed parity check, or recovery is happening */
2719                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
2720                 BUG_ON(s->uptodate != disks);
2721 
2722                 set_bit(R5_LOCKED, &dev->flags);
2723                 s->locked++;
2724                 set_bit(R5_Wantwrite, &dev->flags);
2725 
2726                 clear_bit(STRIPE_DEGRADED, &sh->state);
2727                 set_bit(STRIPE_INSYNC, &sh->state);
2728                 break;
2729         case check_state_run:
2730                 break; /* we will be called again upon completion */
2731         case check_state_check_result:
2732                 sh->check_state = check_state_idle;
2733 
2734                 /* if a failure occurred during the check operation, leave
2735                  * STRIPE_INSYNC not set and let the stripe be handled again
2736                  */
2737                 if (s->failed)
2738                         break;
2739 
2740                 /* handle a successful check operation, if parity is correct
2741                  * we are done.  Otherwise update the mismatch count and repair
2742                  * parity if !MD_RECOVERY_CHECK
2743                  */
2744                 if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
2745                         /* parity is correct (on disc,
2746                          * not in buffer any more)
2747                          */
2748                         set_bit(STRIPE_INSYNC, &sh->state);
2749                 else {
2750                         conf->mddev->resync_mismatches += STRIPE_SECTORS;
2751                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2752                                 /* don't try to repair!! */
2753                                 set_bit(STRIPE_INSYNC, &sh->state);
2754                         else {
2755                                 sh->check_state = check_state_compute_run;
2756                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2757                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2758                                 set_bit(R5_Wantcompute,
2759                                         &sh->dev[sh->pd_idx].flags);
2760                                 sh->ops.target = sh->pd_idx;
2761                                 sh->ops.target2 = -1;
2762                                 s->uptodate++;
2763                         }
2764                 }
2765                 break;
2766         case check_state_compute_run:
2767                 break;
2768         default:
2769                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
2770                        __func__, sh->check_state,
2771                        (unsigned long long) sh->sector);
2772                 BUG();
2773         }
2774 }
2775 
2776 
2777 static void handle_parity_checks6(raid5_conf_t *conf, struct stripe_head *sh,
2778                                   struct stripe_head_state *s,
2779                                   struct r6_state *r6s, int disks)
2780 {
2781         int pd_idx = sh->pd_idx;
2782         int qd_idx = sh->qd_idx;
2783         struct r5dev *dev;
2784 
2785         set_bit(STRIPE_HANDLE, &sh->state);
2786 
2787         BUG_ON(s->failed > 2);
2788 
2789         /* Want to check and possibly repair P and Q.
2790          * However there could be one 'failed' device, in which
2791          * case we can only check one of them, possibly using the
2792          * other to generate missing data
2793          */
2794 
2795         switch (sh->check_state) {
2796         case check_state_idle:
2797                 /* start a new check operation if there are < 2 failures */
2798                 if (s->failed == r6s->q_failed) {
2799                         /* The only possible failed device holds Q, so it
2800                          * makes sense to check P (If anything else were failed,
2801                          * we would have used P to recreate it).
2802                          */
2803                         sh->check_state = check_state_run;
2804                 }
2805                 if (!r6s->q_failed && s->failed < 2) {
2806                         /* Q is not failed, and we didn't use it to generate
2807                          * anything, so it makes sense to check it
2808                          */
2809                         if (sh->check_state == check_state_run)
2810                                 sh->check_state = check_state_run_pq;
2811                         else
2812                                 sh->check_state = check_state_run_q;
2813                 }
2814 
2815                 /* discard potentially stale zero_sum_result */
2816                 sh->ops.zero_sum_result = 0;
2817 
2818                 if (sh->check_state == check_state_run) {
2819                         /* async_xor_zero_sum destroys the contents of P */
2820                         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2821                         s->uptodate--;
2822                 }
2823                 if (sh->check_state >= check_state_run &&
2824                     sh->check_state <= check_state_run_pq) {
2825                         /* async_syndrome_zero_sum preserves P and Q, so
2826                          * no need to mark them !uptodate here
2827                          */
2828                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
2829                         break;
2830                 }
2831 
2832                 /* we have 2-disk failure */
2833                 BUG_ON(s->failed != 2);
2834                 /* fall through */
2835         case check_state_compute_result:
2836                 sh->check_state = check_state_idle;
2837 
2838                 /* check that a write has not made the stripe insync */
2839                 if (test_bit(STRIPE_INSYNC, &sh->state))
2840                         break;
2841 
2842                 /* now write out any block on a failed drive,
2843                  * or P or Q if they were recomputed
2844                  */
2845                 BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
2846                 if (s->failed == 2) {
2847                         dev = &sh->dev[r6s->failed_num[1]];
2848                         s->locked++;
2849                         set_bit(R5_LOCKED, &dev->flags);
2850                         set_bit(R5_Wantwrite, &dev->flags);
2851                 }
2852                 if (s->failed >= 1) {
2853                         dev = &sh->dev[r6s->failed_num[0]];
2854                         s->locked++;
2855                         set_bit(R5_LOCKED, &dev->flags);
2856                         set_bit(R5_Wantwrite, &dev->flags);
2857                 }
2858                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
2859                         dev = &sh->dev[pd_idx];
2860                         s->locked++;
2861                         set_bit(R5_LOCKED, &dev->flags);
2862                         set_bit(R5_Wantwrite, &dev->flags);
2863                 }
2864                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
2865                         dev = &sh->dev[qd_idx];
2866                         s->locked++;
2867                         set_bit(R5_LOCKED, &dev->flags);
2868                         set_bit(R5_Wantwrite, &dev->flags);
2869                 }
2870                 clear_bit(STRIPE_DEGRADED, &sh->state);
2871 
2872                 set_bit(STRIPE_INSYNC, &sh->state);
2873                 break;
2874         case check_state_run:
2875         case check_state_run_q:
2876         case check_state_run_pq:
2877                 break; /* we will be called again upon completion */
2878         case check_state_check_result:
2879                 sh->check_state = check_state_idle;
2880 
2881                 /* handle a successful check operation, if parity is correct
2882                  * we are done.  Otherwise update the mismatch count and repair
2883                  * parity if !MD_RECOVERY_CHECK
2884                  */
2885                 if (sh->ops.zero_sum_result == 0) {
2886                         /* both parities are correct */
2887                         if (!s->failed)
2888                                 set_bit(STRIPE_INSYNC, &sh->state);
2889                         else {
2890                                 /* in contrast to the raid5 case we can validate
2891                                  * parity, but still have a failure to write
2892                                  * back
2893                                  */
2894                                 sh->check_state = check_state_compute_result;
2895                                 /* Returning at this point means that we may go
2896                                  * off and bring p and/or q uptodate again so
2897                                  * we make sure to check zero_sum_result again
2898                                  * to verify if p or q need writeback
2899                                  */
2900                         }
2901                 } else {
2902                         conf->mddev->resync_mismatches += STRIPE_SECTORS;
2903                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
2904                                 /* don't try to repair!! */
2905                                 set_bit(STRIPE_INSYNC, &sh->state);
2906                         else {
2907                                 int *target = &sh->ops.target;
2908 
2909                                 sh->ops.target = -1;
2910                                 sh->ops.target2 = -1;
2911                                 sh->check_state = check_state_compute_run;
2912                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2913                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2914                                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
2915                                         set_bit(R5_Wantcompute,
2916                                                 &sh->dev[pd_idx].flags);
2917                                         *target = pd_idx;
2918                                         target = &sh->ops.target2;
2919                                         s->uptodate++;
2920                                 }
2921                                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
2922                                         set_bit(R5_Wantcompute,
2923                                                 &sh->dev[qd_idx].flags);
2924                                         *target = qd_idx;
2925                                         s->uptodate++;
2926                                 }
2927                         }
2928                 }
2929                 break;
2930         case check_state_compute_run:
2931                 break;
2932         default:
2933                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
2934                        __func__, sh->check_state,
2935                        (unsigned long long) sh->sector);
2936                 BUG();
2937         }
2938 }
2939 
2940 static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
2941                                 struct r6_state *r6s)
2942 {
2943         int i;
2944 
2945         /* We have read all the blocks in this stripe and now we need to
2946          * copy some of them into a target stripe for expand.
2947          */
2948         struct dma_async_tx_descriptor *tx = NULL;
2949         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
2950         for (i = 0; i < sh->disks; i++)
2951                 if (i != sh->pd_idx && i != sh->qd_idx) {
2952                         int dd_idx, j;
2953                         struct stripe_head *sh2;
2954                         struct async_submit_ctl submit;
2955 
2956                         sector_t bn = compute_blocknr(sh, i, 1);
2957                         sector_t s = raid5_compute_sector(conf, bn, 0,
2958                                                           &dd_idx, NULL);
2959                         sh2 = get_active_stripe(conf, s, 0, 1, 1);
2960                         if (sh2 == NULL)
2961                                 /* so far only the early blocks of this stripe
2962                                  * have been requested.  When later blocks
2963                                  * get requested, we will try again
2964                                  */
2965                                 continue;
2966                         if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
2967                            test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
2968                                 /* must have already done this block */
2969                                 release_stripe(sh2);
2970                                 continue;
2971                         }
2972 
2973                         /* place all the copies on one channel */
2974                         init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
2975                         tx = async_memcpy(sh2->dev[dd_idx].page,
2976                                           sh->dev[i].page, 0, 0, STRIPE_SIZE,
2977                                           &submit);
2978 
2979                         set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
2980                         set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
2981                         for (j = 0; j < conf->raid_disks; j++)
2982                                 if (j != sh2->pd_idx &&
2983                                     (!r6s || j != sh2->qd_idx) &&
2984                                     !test_bit(R5_Expanded, &sh2->dev[j].flags))
2985                                         break;
2986                         if (j == conf->raid_disks) {
2987                                 set_bit(STRIPE_EXPAND_READY, &sh2->state);
2988                                 set_bit(STRIPE_HANDLE, &sh2->state);
2989                         }
2990                         release_stripe(sh2);
2991 
2992                 }
2993         /* done submitting copies, wait for them to complete */
2994         if (tx) {
2995                 async_tx_ack(tx);
2996                 dma_wait_for_async_tx(tx);
2997         }
2998 }
2999 
3000 
3001 /*
3002  * handle_stripe - do things to a stripe.
3003  *
3004  * We lock the stripe and then examine the state of various bits
3005  * to see what needs to be done.
3006  * Possible results:
3007  *    return some read request which now have data
3008  *    return some write requests which are safely on disc
3009  *    schedule a read on some buffers
3010  *    schedule a write of some buffers
3011  *    return confirmation of parity correctness
3012  *
3013  * buffers are taken off read_list or write_list, and bh_cache buffers
3014  * get BH_Lock set before the stripe lock is released.
3015  *
3016  */
3017 
3018 static void handle_stripe5(struct stripe_head *sh)
3019 {
3020         raid5_conf_t *conf = sh->raid_conf;
3021         int disks = sh->disks, i;
3022         struct bio *return_bi = NULL;
3023         struct stripe_head_state s;
3024         struct r5dev *dev;
3025         mdk_rdev_t *blocked_rdev = NULL;
3026         int prexor;
3027         int dec_preread_active = 0;
3028 
3029         memset(&s, 0, sizeof(s));
3030         pr_debug("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d check:%d "
3031                  "reconstruct:%d\n", (unsigned long long)sh->sector, sh->state,
3032                  atomic_read(&sh->count), sh->pd_idx, sh->check_state,
3033                  sh->reconstruct_state);
3034 
3035         spin_lock(&sh->lock);
3036         clear_bit(STRIPE_HANDLE, &sh->state);
3037         clear_bit(STRIPE_DELAYED, &sh->state);
3038 
3039         s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
3040         s.expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3041         s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
3042 
3043         /* Now to look around and see what can be done */
3044         rcu_read_lock();
3045         for (i=disks; i--; ) {
3046                 mdk_rdev_t *rdev;
3047 
3048                 dev = &sh->dev[i];
3049 
3050                 pr_debug("check %d: state 0x%lx toread %p read %p write %p "
3051                         "written %p\n", i, dev->flags, dev->toread, dev->read,
3052                         dev->towrite, dev->written);
3053 
3054                 /* maybe we can request a biofill operation
3055                  *
3056                  * new wantfill requests are only permitted while
3057                  * ops_complete_biofill is guaranteed to be inactive
3058                  */
3059                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
3060                     !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
3061                         set_bit(R5_Wantfill, &dev->flags);
3062 
3063                 /* now count some things */
3064                 if (test_bit(R5_LOCKED, &dev->flags)) s.locked++;
3065                 if (test_bit(R5_UPTODATE, &dev->flags)) s.uptodate++;
3066                 if (test_bit(R5_Wantcompute, &dev->flags)) s.compute++;
3067 
3068                 if (test_bit(R5_Wantfill, &dev->flags))
3069                         s.to_fill++;
3070                 else if (dev->toread)
3071                         s.to_read++;
3072                 if (dev->towrite) {
3073                         s.to_write++;
3074                         if (!test_bit(R5_OVERWRITE, &dev->flags))
3075                                 s.non_overwrite++;
3076                 }
3077                 if (dev->written)
3078                         s.written++;
3079                 rdev = rcu_dereference(conf->disks[i].rdev);
3080                 if (blocked_rdev == NULL &&
3081                     rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
3082                         blocked_rdev = rdev;
3083                         atomic_inc(&rdev->nr_pending);
3084                 }
3085                 clear_bit(R5_Insync, &dev->flags);
3086                 if (!rdev)
3087                         /* Not in-sync */;
3088                 else if (test_bit(In_sync, &rdev->flags))
3089                         set_bit(R5_Insync, &dev->flags);
3090                 else {
3091                         /* could be in-sync depending on recovery/reshape status */
3092                         if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
3093                                 set_bit(R5_Insync, &dev->flags);
3094                 }
3095                 if (!test_bit(R5_Insync, &dev->flags)) {
3096                         /* The ReadError flag will just be confusing now */
3097                         clear_bit(R5_ReadError, &dev->flags);
3098                         clear_bit(R5_ReWrite, &dev->flags);
3099                 }
3100                 if (test_bit(R5_ReadError, &dev->flags))
3101                         clear_bit(R5_Insync, &dev->flags);
3102                 if (!test_bit(R5_Insync, &dev->flags)) {
3103                         s.failed++;
3104                         s.failed_num = i;
3105                 }
3106         }
3107         rcu_read_unlock();
3108 
3109         if (unlikely(blocked_rdev)) {
3110                 if (s.syncing || s.expanding || s.expanded ||
3111                     s.to_write || s.written) {
3112                         set_bit(STRIPE_HANDLE, &sh->state);
3113                         goto unlock;
3114                 }
3115                 /* There is nothing for the blocked_rdev to block */
3116                 rdev_dec_pending(blocked_rdev, conf->mddev);
3117                 blocked_rdev = NULL;
3118         }
3119 
3120         if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
3121                 set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
3122                 set_bit(STRIPE_BIOFILL_RUN, &sh->state);
3123         }
3124 
3125         pr_debug("locked=%d uptodate=%d to_read=%d"
3126                 " to_write=%d failed=%d failed_num=%d\n",
3127                 s.locked, s.uptodate, s.to_read, s.to_write,
3128                 s.failed, s.failed_num);
3129         /* check if the array has lost two devices and, if so, some requests might
3130          * need to be failed
3131          */
3132         if (s.failed > 1 && s.to_read+s.to_write+s.written)
3133                 handle_failed_stripe(conf, sh, &s, disks, &return_bi);
3134         if (s.failed > 1 && s.syncing) {
3135                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
3136                 clear_bit(STRIPE_SYNCING, &sh->state);
3137                 s.syncing = 0;
3138         }
3139 
3140         /* might be able to return some write requests if the parity block
3141          * is safe, or on a failed drive
3142          */
3143         dev = &sh->dev[sh->pd_idx];
3144         if ( s.written &&
3145              ((test_bit(R5_Insync, &dev->flags) &&
3146                !test_bit(R5_LOCKED, &dev->flags) &&
3147                test_bit(R5_UPTODATE, &dev->flags)) ||
3148                (s.failed == 1 && s.failed_num == sh->pd_idx)))
3149                 handle_stripe_clean_event(conf, sh, disks, &return_bi);
3150 
3151         /* Now we might consider reading some blocks, either to check/generate
3152          * parity, or to satisfy requests
3153          * or to load a block that is being partially written.
3154          */
3155         if (s.to_read || s.non_overwrite ||
3156             (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding)
3157                 handle_stripe_fill5(sh, &s, disks);
3158 
3159         /* Now we check to see if any write operations have recently
3160          * completed
3161          */
3162         prexor = 0;
3163         if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
3164                 prexor = 1;
3165         if (sh->reconstruct_state == reconstruct_state_drain_result ||
3166             sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
3167                 sh->reconstruct_state = reconstruct_state_idle;
3168 
3169                 /* All the 'written' buffers and the parity block are ready to
3170                  * be written back to disk
3171                  */
3172                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags));
3173                 for (i = disks; i--; ) {
3174                         dev = &sh->dev[i];
3175                         if (test_bit(R5_LOCKED, &dev->flags) &&
3176                                 (i == sh->pd_idx || dev->written)) {
3177                                 pr_debug("Writing block %d\n", i);
3178                                 set_bit(R5_Wantwrite, &dev->flags);
3179                                 if (prexor)
3180                                         continue;
3181                                 if (!test_bit(R5_Insync, &dev->flags) ||
3182                                     (i == sh->pd_idx && s.failed == 0))
3183                                         set_bit(STRIPE_INSYNC, &sh->state);
3184                         }
3185                 }
3186                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3187                         dec_preread_active = 1;
3188         }
3189 
3190         /* Now to consider new write requests and what else, if anything
3191          * should be read.  We do not handle new writes when:
3192          * 1/ A 'write' operation (copy+xor) is already in flight.
3193          * 2/ A 'check' operation is in flight, as it may clobber the parity
3194          *    block.
3195          */
3196         if (s.to_write && !sh->reconstruct_state && !sh->check_state)
3197                 handle_stripe_dirtying5(conf, sh, &s, disks);
3198 
3199         /* maybe we need to check and possibly fix the parity for this stripe
3200          * Any reads will already have been scheduled, so we just see if enough
3201          * data is available.  The parity check is held off while parity
3202          * dependent operations are in flight.
3203          */
3204         if (sh->check_state ||
3205             (s.syncing && s.locked == 0 &&
3206              !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3207              !test_bit(STRIPE_INSYNC, &sh->state)))
3208                 handle_parity_checks5(conf, sh, &s, disks);
3209 
3210         if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
3211                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
3212                 clear_bit(STRIPE_SYNCING, &sh->state);
3213         }
3214 
3215         /* If the failed drive is just a ReadError, then we might need to progress
3216          * the repair/check process
3217          */
3218         if (s.failed == 1 && !conf->mddev->ro &&
3219             test_bit(R5_ReadError, &sh->dev[s.failed_num].flags)
3220             && !test_bit(R5_LOCKED, &sh->dev[s.failed_num].flags)
3221             && test_bit(R5_UPTODATE, &sh->dev[s.failed_num].flags)
3222                 ) {
3223                 dev = &sh->dev[s.failed_num];
3224                 if (!test_bit(R5_ReWrite, &dev->flags)) {
3225                         set_bit(R5_Wantwrite, &dev->flags);
3226                         set_bit(R5_ReWrite, &dev->flags);
3227                         set_bit(R5_LOCKED, &dev->flags);
3228                         s.locked++;
3229                 } else {
3230                         /* let's read it back */
3231                         set_bit(R5_Wantread, &dev->flags);
3232                         set_bit(R5_LOCKED, &dev->flags);
3233                         s.locked++;
3234                 }
3235         }
3236 
3237         /* Finish reconstruct operations initiated by the expansion process */
3238         if (sh->reconstruct_state == reconstruct_state_result) {
3239                 struct stripe_head *sh2
3240                         = get_active_stripe(conf, sh->sector, 1, 1, 1);
3241                 if (sh2 && test_bit(STRIPE_EXPAND_SOURCE, &sh2->state)) {
3242                         /* sh cannot be written until sh2 has been read.
3243                          * so arrange for sh to be delayed a little
3244                          */
3245                         set_bit(STRIPE_DELAYED, &sh->state);
3246                         set_bit(STRIPE_HANDLE, &sh->state);
3247                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
3248                                               &sh2->state))
3249                                 atomic_inc(&conf->preread_active_stripes);
3250                         release_stripe(sh2);
3251                         goto unlock;
3252                 }
3253                 if (sh2)
3254                         release_stripe(sh2);
3255 
3256                 sh->reconstruct_state = reconstruct_state_idle;
3257                 clear_bit(STRIPE_EXPANDING, &sh->state);
3258                 for (i = conf->raid_disks; i--; ) {
3259                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
3260                         set_bit(R5_LOCKED, &sh->dev[i].flags);
3261                         s.locked++;
3262                 }
3263         }
3264 
3265         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
3266             !sh->reconstruct_state) {
3267                 /* Need to write out all blocks after computing parity */
3268                 sh->disks = conf->raid_disks;
3269                 stripe_set_idx(sh->sector, conf, 0, sh);
3270                 schedule_reconstruction(sh, &s, 1, 1);
3271         } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
3272                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
3273                 atomic_dec(&conf->reshape_stripes);
3274                 wake_up(&conf->wait_for_overlap);
3275                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3276         }
3277 
3278         if (s.expanding && s.locked == 0 &&
3279             !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
3280                 handle_stripe_expansion(conf, sh, NULL);
3281 
3282  unlock:
3283         spin_unlock(&sh->lock);
3284 
3285         /* wait for this device to become unblocked */
3286         if (unlikely(blocked_rdev))
3287                 md_wait_for_blocked_rdev(blocked_rdev, conf->mddev);
3288 
3289         if (s.ops_request)
3290                 raid_run_ops(sh, s.ops_request);
3291 
3292         ops_run_io(sh, &s);
3293 
3294         if (dec_preread_active) {
3295                 /* We delay this until after ops_run_io so that if make_request
3296                  * is waiting on a flush, it won't continue until the writes
3297                  * have actually been submitted.
3298                  */
3299                 atomic_dec(&conf->preread_active_stripes);
3300                 if (atomic_read(&conf->preread_active_stripes) <
3301                     IO_THRESHOLD)
3302                         md_wakeup_thread(conf->mddev->thread);
3303         }
3304         return_io(return_bi);
3305 }
3306 
3307 static void handle_stripe6(struct stripe_head *sh)
3308 {
3309         raid5_conf_t *conf = sh->raid_conf;
3310         int disks = sh->disks;
3311         struct bio *return_bi = NULL;
3312         int i, pd_idx = sh->pd_idx, qd_idx = sh->qd_idx;
3313         struct stripe_head_state s;
3314         struct r6_state r6s;
3315         struct r5dev *dev, *pdev, *qdev;
3316         mdk_rdev_t *blocked_rdev = NULL;
3317         int dec_preread_active = 0;
3318 
3319         pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
3320                 "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
3321                (unsigned long long)sh->sector, sh->state,
3322                atomic_read(&sh->count), pd_idx, qd_idx,
3323                sh->check_state, sh->reconstruct_state);
3324         memset(&s, 0, sizeof(s));
3325 
3326         spin_lock(&sh->lock);
3327         clear_bit(STRIPE_HANDLE, &sh->state);
3328         clear_bit(STRIPE_DELAYED, &sh->state);
3329 
3330         s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
3331         s.expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3332         s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
3333         /* Now to look around and see what can be done */
3334 
3335         rcu_read_lock();
3336         for (i=disks; i--; ) {
3337                 mdk_rdev_t *rdev;
3338                 dev = &sh->dev[i];
3339 
3340                 pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
3341                         i, dev->flags, dev->toread, dev->towrite, dev->written);
3342                 /* maybe we can reply to a read
3343                  *
3344                  * new wantfill requests are only permitted while
3345                  * ops_complete_biofill is guaranteed to be inactive
3346                  */
3347                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
3348                     !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
3349                         set_bit(R5_Wantfill, &dev->flags);
3350 
3351                 /* now count some things */
3352                 if (test_bit(R5_LOCKED, &dev->flags)) s.locked++;
3353                 if (test_bit(R5_UPTODATE, &dev->flags)) s.uptodate++;
3354                 if (test_bit(R5_Wantcompute, &dev->flags)) {
3355                         s.compute++;
3356                         BUG_ON(s.compute > 2);
3357                 }
3358 
3359                 if (test_bit(R5_Wantfill, &dev->flags)) {
3360                         s.to_fill++;
3361                 } else if (dev->toread)
3362                         s.to_read++;
3363                 if (dev->towrite) {
3364                         s.to_write++;
3365                         if (!test_bit(R5_OVERWRITE, &dev->flags))
3366                                 s.non_overwrite++;
3367                 }
3368                 if (dev->written)
3369                         s.written++;
3370                 rdev = rcu_dereference(conf->disks[i].rdev);
3371                 if (blocked_rdev == NULL &&
3372                     rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
3373                         blocked_rdev = rdev;
3374                         atomic_inc(&rdev->nr_pending);
3375                 }
3376                 clear_bit(R5_Insync, &dev->flags);
3377                 if (!rdev)
3378                         /* Not in-sync */;
3379                 else if (test_bit(In_sync, &rdev->flags))
3380                         set_bit(R5_Insync, &dev->flags);
3381                 else {
3382                         /* in sync if before recovery_offset */
3383                         if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
3384                                 set_bit(R5_Insync, &dev->flags);
3385                 }
3386                 if (!test_bit(R5_Insync, &dev->flags)) {
3387                         /* The ReadError flag will just be confusing now */
3388                         clear_bit(R5_ReadError, &dev->flags);
3389                         clear_bit(R5_ReWrite, &dev->flags);
3390                 }
3391                 if (test_bit(R5_ReadError, &dev->flags))
3392                         clear_bit(R5_Insync, &dev->flags);
3393                 if (!test_bit(R5_Insync, &dev->flags)) {
3394                         if (s.failed < 2)
3395                                 r6s.failed_num[s.failed] = i;
3396                         s.failed++;
3397                 }
3398         }
3399         rcu_read_unlock();
3400 
3401         if (unlikely(blocked_rdev)) {
3402                 if (s.syncing || s.expanding || s.expanded ||
3403                     s.to_write || s.written) {
3404                         set_bit(STRIPE_HANDLE, &sh->state);
3405                         goto unlock;
3406                 }
3407                 /* There is nothing for the blocked_rdev to block */
3408                 rdev_dec_pending(blocked_rdev, conf->mddev);
3409                 blocked_rdev = NULL;
3410         }
3411 
3412         if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
3413                 set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
3414                 set_bit(STRIPE_BIOFILL_RUN, &sh->state);
3415         }
3416 
3417         pr_debug("locked=%d uptodate=%d to_read=%d"
3418                " to_write=%d failed=%d failed_num=%d,%d\n",
3419                s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
3420                r6s.failed_num[0], r6s.failed_num[1]);
3421         /* check if the array has lost >2 devices and, if so, some requests
3422          * might need to be failed
3423          */
3424         if (s.failed > 2 && s.to_read+s.to_write+s.written)
3425                 handle_failed_stripe(conf, sh, &s, disks, &return_bi);
3426         if (s.failed > 2 && s.syncing) {
3427                 md_done_sync(conf->mddev, STRIPE_SECTORS,0);
3428                 clear_bit(STRIPE_SYNCING, &sh->state);
3429                 s.syncing = 0;
3430         }
3431 
3432         /*
3433          * might be able to return some write requests if the parity blocks
3434          * are safe, or on a failed drive
3435          */
3436         pdev = &sh->dev[pd_idx];
3437         r6s.p_failed = (s.failed >= 1 && r6s.failed_num[0] == pd_idx)
3438                 || (s.failed >= 2 && r6s.failed_num[1] == pd_idx);
3439         qdev = &sh->dev[qd_idx];
3440         r6s.q_failed = (s.failed >= 1 && r6s.failed_num[0] == qd_idx)
3441                 || (s.failed >= 2 && r6s.failed_num[1] == qd_idx);
3442 
3443         if ( s.written &&
3444              ( r6s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
3445                              && !test_bit(R5_LOCKED, &pdev->flags)
3446                              && test_bit(R5_UPTODATE, &pdev->flags)))) &&
3447              ( r6s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
3448                              && !test_bit(R5_LOCKED, &qdev->flags)
3449                              && test_bit(R5_UPTODATE, &qdev->flags)))))
3450                 handle_stripe_clean_event(conf, sh, disks, &return_bi);
3451 
3452         /* Now we might consider reading some blocks, either to check/generate
3453          * parity, or to satisfy requests
3454          * or to load a block that is being partially written.
3455          */
3456         if (s.to_read || s.non_overwrite || (s.to_write && s.failed) ||
3457             (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding)
3458                 handle_stripe_fill6(sh, &s, &r6s, disks);
3459 
3460         /* Now we check to see if any write operations have recently
3461          * completed
3462          */
3463         if (sh->reconstruct_state == reconstruct_state_drain_result) {
3464 
3465                 sh->reconstruct_state = reconstruct_state_idle;
3466                 /* All the 'written' buffers and the parity blocks are ready to
3467                  * be written back to disk
3468                  */
3469                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags));
3470                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[qd_idx].flags));
3471                 for (i = disks; i--; ) {
3472                         dev = &sh->dev[i];
3473                         if (test_bit(R5_LOCKED, &dev->flags) &&
3474                             (i == sh->pd_idx || i == qd_idx ||
3475                              dev->written)) {
3476                                 pr_debug("Writing block %d\n", i);
3477                                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
3478                                 set_bit(R5_Wantwrite, &dev->flags);
3479                                 if (!test_bit(R5_Insync, &dev->flags) ||
3480                                     ((i == sh->pd_idx || i == qd_idx) &&
3481                                       s.failed == 0))
3482                                         set_bit(STRIPE_INSYNC, &sh->state);
3483                         }
3484                 }
3485                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3486                         dec_preread_active = 1;
3487         }
3488 
3489         /* Now to consider new write requests and what else, if anything
3490          * should be read.  We do not handle new writes when:
3491          * 1/ A 'write' operation (copy+gen_syndrome) is already in flight.
3492          * 2/ A 'check' operation is in flight, as it may clobber the parity
3493          *    block.
3494          */
3495         if (s.to_write && !sh->reconstruct_state && !sh->check_state)
3496                 handle_stripe_dirtying6(conf, sh, &s, &r6s, disks);
3497 
3498         /* maybe we need to check and possibly fix the parity for this stripe
3499          * Any reads will already have been scheduled, so we just see if enough
3500          * data is available.  The parity check is held off while parity
3501          * dependent operations are in flight.
3502          */
3503         if (sh->check_state ||
3504             (s.syncing && s.locked == 0 &&
3505              !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3506              !test_bit(STRIPE_INSYNC, &sh->state)))
3507                 handle_parity_checks6(conf, sh, &s, &r6s, disks);
3508 
3509         if (s.syncing && s.locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
3510                 md_done_sync(conf->mddev, STRIPE_SECTORS,1);
3511                 clear_bit(STRIPE_SYNCING, &sh->state);
3512         }
3513 
3514         /* If the failed drives are just a ReadError, then we might need
3515          * to progress the repair/check process
3516          */
3517         if (s.failed <= 2 && !conf->mddev->ro)
3518                 for (i = 0; i < s.failed; i++) {
3519                         dev = &sh->dev[r6s.failed_num[i]];
3520                         if (test_bit(R5_ReadError, &dev->flags)
3521                             && !test_bit(R5_LOCKED, &dev->flags)
3522                             && test_bit(R5_UPTODATE, &dev->flags)
3523                                 ) {
3524                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
3525                                         set_bit(R5_Wantwrite, &dev->flags);
3526                                         set_bit(R5_ReWrite, &dev->flags);
3527                                         set_bit(R5_LOCKED, &dev->flags);
3528                                         s.locked++;
3529                                 } else {
3530                                         /* let's read it back */
3531                                         set_bit(R5_Wantread, &dev->flags);
3532                                         set_bit(R5_LOCKED, &dev->flags);
3533                                         s.locked++;
3534                                 }
3535                         }
3536                 }
3537 
3538         /* Finish reconstruct operations initiated by the expansion process */
3539         if (sh->reconstruct_state == reconstruct_state_result) {
3540                 sh->reconstruct_state = reconstruct_state_idle;
3541                 clear_bit(STRIPE_EXPANDING, &sh->state);
3542                 for (i = conf->raid_disks; i--; ) {
3543                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
3544                         set_bit(R5_LOCKED, &sh->dev[i].flags);
3545                         s.locked++;
3546                 }
3547         }
3548 
3549         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
3550             !sh->reconstruct_state) {
3551                 struct stripe_head *sh2
3552                         = get_active_stripe(conf, sh->sector, 1, 1, 1);
3553                 if (sh2 && test_bit(STRIPE_EXPAND_SOURCE, &sh2->state)) {
3554                         /* sh cannot be written until sh2 has been read.
3555                          * so arrange for sh to be delayed a little
3556                          */
3557                         set_bit(STRIPE_DELAYED, &sh->state);
3558                         set_bit(STRIPE_HANDLE, &sh->state);
3559                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
3560                                               &sh2->state))
3561                                 atomic_inc(&conf->preread_active_stripes);
3562                         release_stripe(sh2);
3563                         goto unlock;
3564                 }
3565                 if (sh2)
3566                         release_stripe(sh2);
3567 
3568                 /* Need to write out all blocks after computing P&Q */
3569                 sh->disks = conf->raid_disks;
3570                 stripe_set_idx(sh->sector, conf, 0, sh);
3571                 schedule_reconstruction(sh, &s, 1, 1);
3572         } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
3573                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
3574                 atomic_dec(&conf->reshape_stripes);
3575                 wake_up(&conf->wait_for_overlap);
3576                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3577         }
3578 
3579         if (s.expanding && s.locked == 0 &&
3580             !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
3581                 handle_stripe_expansion(conf, sh, &r6s);
3582 
3583  unlock:
3584         spin_unlock(&sh->lock);
3585 
3586         /* wait for this device to become unblocked */
3587         if (unlikely(blocked_rdev))
3588                 md_wait_for_blocked_rdev(blocked_rdev, conf->mddev);
3589 
3590         if (s.ops_request)
3591                 raid_run_ops(sh, s.ops_request);
3592 
3593         ops_run_io(sh, &s);
3594 
3595 
3596         if (dec_preread_active) {
3597                 /* We delay this until after ops_run_io so that if make_request
3598                  * is waiting on a flush, it won't continue until the writes
3599                  * have actually been submitted.
3600                  */
3601                 atomic_dec(&conf->preread_active_stripes);
3602                 if (atomic_read(&conf->preread_active_stripes) <
3603                     IO_THRESHOLD)
3604                         md_wakeup_thread(conf->mddev->thread);
3605         }
3606 
3607         return_io(return_bi);
3608 }
3609 
3610 static void handle_stripe(struct stripe_head *sh)
3611 {
3612         if (sh->raid_conf->level == 6)
3613                 handle_stripe6(sh);
3614         else
3615                 handle_stripe5(sh);
3616 }
3617 
3618 static void raid5_activate_delayed(raid5_conf_t *conf)
3619 {
3620         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
3621                 while (!list_empty(&conf->delayed_list)) {
3622                         struct list_head *l = conf->delayed_list.next;
3623                         struct stripe_head *sh;
3624                         sh = list_entry(l, struct stripe_head, lru);
3625                         list_del_init(l);
3626                         clear_bit(STRIPE_DELAYED, &sh->state);
3627                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3628                                 atomic_inc(&conf->preread_active_stripes);
3629                         list_add_tail(&sh->lru, &conf->hold_list);
3630                 }
3631         } else
3632                 plugger_set_plug(&conf->plug);
3633 }
3634 
3635 static void activate_bit_delay(raid5_conf_t *conf)
3636 {
3637         /* device_lock is held */
3638         struct list_head head;
3639         list_add(&head, &conf->bitmap_list);
3640         list_del_init(&conf->bitmap_list);
3641         while (!list_empty(&head)) {
3642                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
3643                 list_del_init(&sh->lru);
3644                 atomic_inc(&sh->count);
3645                 __release_stripe(conf, sh);
3646         }
3647 }
3648 
3649 static void unplug_slaves(mddev_t *mddev)
3650 {
3651         raid5_conf_t *conf = mddev->private;
3652         int i;
3653         int devs = max(conf->raid_disks, conf->previous_raid_disks);
3654 
3655         rcu_read_lock();
3656         for (i = 0; i < devs; i++) {
3657                 mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
3658                 if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
3659                         struct request_queue *r_queue = bdev_get_queue(rdev->bdev);
3660 
3661                         atomic_inc(&rdev->nr_pending);
3662                         rcu_read_unlock();
3663 
3664                         blk_unplug(r_queue);
3665 
3666                         rdev_dec_pending(rdev, mddev);
3667                         rcu_read_lock();
3668                 }
3669         }
3670         rcu_read_unlock();
3671 }
3672 
3673 void md_raid5_unplug_device(raid5_conf_t *conf)
3674 {
3675         unsigned long flags;
3676 
3677         spin_lock_irqsave(&conf->device_lock, flags);
3678 
3679         if (plugger_remove_plug(&conf->plug)) {
3680                 conf->seq_flush++;
3681                 raid5_activate_delayed(conf);
3682         }
3683         md_wakeup_thread(conf->mddev->thread);
3684 
3685         spin_unlock_irqrestore(&conf->device_lock, flags);
3686 
3687         unplug_slaves(conf->mddev);
3688 }
3689 EXPORT_SYMBOL_GPL(md_raid5_unplug_device);
3690 
3691 static void raid5_unplug(struct plug_handle *plug)
3692 {
3693         raid5_conf_t *conf = container_of(plug, raid5_conf_t, plug);
3694         md_raid5_unplug_device(conf);
3695 }
3696 
3697 static void raid5_unplug_queue(struct request_queue *q)
3698 {
3699         mddev_t *mddev = q->queuedata;
3700         md_raid5_unplug_device(mddev->private);
3701 }
3702 
3703 int md_raid5_congested(mddev_t *mddev, int bits)
3704 {
3705         raid5_conf_t *conf = mddev->private;
3706 
3707         /* No difference between reads and writes.  Just check
3708          * how busy the stripe_cache is
3709          */
3710 
3711         if (conf->inactive_blocked)
3712                 return 1;
3713         if (conf->quiesce)
3714                 return 1;
3715         if (list_empty_careful(&conf->inactive_list))
3716                 return 1;
3717 
3718         return 0;
3719 }
3720 EXPORT_SYMBOL_GPL(md_raid5_congested);
3721 
3722 static int raid5_congested(void *data, int bits)
3723 {
3724         mddev_t *mddev = data;
3725 
3726         return mddev_congested(mddev, bits) ||
3727                 md_raid5_congested(mddev, bits);
3728 }
3729 
3730 /* We want read requests to align with chunks where possible,
3731  * but write requests don't need to.
3732  */
3733 static int raid5_mergeable_bvec(struct request_queue *q,
3734                                 struct bvec_merge_data *bvm,
3735                                 struct bio_vec *biovec)
3736 {
3737         mddev_t *mddev = q->queuedata;
3738         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
3739         int max;
3740         unsigned int chunk_sectors = mddev->chunk_sectors;
3741         unsigned int bio_sectors = bvm->bi_size >> 9;
3742 
3743         if ((bvm->bi_rw & 1) == WRITE)
3744                 return biovec->bv_len; /* always allow writes to be mergeable */
3745 
3746         if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3747                 chunk_sectors = mddev->new_chunk_sectors;
3748         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
3749         if (max < 0) max = 0;
3750         if (max <= biovec->bv_len && bio_sectors == 0)
3751                 return biovec->bv_len;
3752         else
3753                 return max;
3754 }
3755 
3756 
3757 static int in_chunk_boundary(mddev_t *mddev, struct bio *bio)
3758 {
3759         sector_t sector = bio->bi_sector + get_start_sect(bio->bi_bdev);
3760         unsigned int chunk_sectors = mddev->chunk_sectors;
3761         unsigned int bio_sectors = bio->bi_size >> 9;
3762 
3763         if (mddev->new_chunk_sectors < mddev->chunk_sectors)
3764                 chunk_sectors = mddev->new_chunk_sectors;
3765         return  chunk_sectors >=
3766                 ((sector & (chunk_sectors - 1)) + bio_sectors);
3767 }
3768 
3769 /*
3770  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
3771  *  later sampled by raid5d.
3772  */
3773 static void add_bio_to_retry(struct bio *bi,raid5_conf_t *conf)
3774 {
3775         unsigned long flags;
3776 
3777         spin_lock_irqsave(&conf->device_lock, flags);
3778 
3779         bi->bi_next = conf->retry_read_aligned_list;
3780         conf->retry_read_aligned_list = bi;
3781 
3782         spin_unlock_irqrestore(&conf->device_lock, flags);
3783         md_wakeup_thread(conf->mddev->thread);
3784 }
3785 
3786 
3787 static struct bio *remove_bio_from_retry(raid5_conf_t *conf)
3788 {
3789         struct bio *bi;
3790 
3791         bi = conf->retry_read_aligned;
3792         if (bi) {
3793                 conf->retry_read_aligned = NULL;
3794                 return bi;
3795         }
3796         bi = conf->retry_read_aligned_list;
3797         if(bi) {
3798                 conf->retry_read_aligned_list = bi->bi_next;
3799                 bi->bi_next = NULL;
3800                 /*
3801                  * this sets the active strip count to 1 and the processed
3802                  * strip count to zero (upper 8 bits)
3803                  */
3804                 bi->bi_phys_segments = 1; /* biased count of active stripes */
3805         }
3806 
3807         return bi;
3808 }
3809 
3810 
3811 /*
3812  *  The "raid5_align_endio" should check if the read succeeded and if it
3813  *  did, call bio_endio on the original bio (having bio_put the new bio
3814  *  first).
3815  *  If the read failed..
3816  */
3817 static void raid5_align_endio(struct bio *bi, int error)
3818 {
3819         struct bio* raid_bi  = bi->bi_private;
3820         mddev_t *mddev;
3821         raid5_conf_t *conf;
3822         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
3823         mdk_rdev_t *rdev;
3824 
3825         bio_put(bi);
3826 
3827         rdev = (void*)raid_bi->bi_next;
3828         raid_bi->bi_next = NULL;
3829         mddev = rdev->mddev;
3830         conf = mddev->private;
3831 
3832         rdev_dec_pending(rdev, conf->mddev);
3833 
3834         if (!error && uptodate) {
3835                 bio_endio(raid_bi, 0);
3836                 if (atomic_dec_and_test(&conf->active_aligned_reads))
3837                         wake_up(&conf->wait_for_stripe);
3838                 return;
3839         }
3840 
3841 
3842         pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
3843 
3844         add_bio_to_retry(raid_bi, conf);
3845 }
3846 
3847 static int bio_fits_rdev(struct bio *bi)
3848 {
3849         struct request_queue *q = bdev_get_queue(bi->bi_bdev);
3850 
3851         if ((bi->bi_size>>9) > queue_max_sectors(q))
3852                 return 0;
3853         blk_recount_segments(q, bi);
3854         if (bi->bi_phys_segments > queue_max_segments(q))
3855                 return 0;
3856 
3857         if (q->merge_bvec_fn)
3858                 /* it's too hard to apply the merge_bvec_fn at this stage,
3859                  * just just give up
3860                  */
3861                 return 0;
3862 
3863         return 1;
3864 }
3865 
3866 
3867 static int chunk_aligned_read(mddev_t *mddev, struct bio * raid_bio)
3868 {
3869         raid5_conf_t *conf = mddev->private;
3870         int dd_idx;
3871         struct bio* align_bi;
3872         mdk_rdev_t *rdev;
3873 
3874         if (!in_chunk_boundary(mddev, raid_bio)) {
3875                 pr_debug("chunk_aligned_read : non aligned\n");
3876                 return 0;
3877         }
3878         /*
3879          * use bio_clone_mddev to make a copy of the bio
3880          */
3881         align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
3882         if (!align_bi)
3883                 return 0;
3884         /*
3885          *   set bi_end_io to a new function, and set bi_private to the
3886          *     original bio.
3887          */
3888         align_bi->bi_end_io  = raid5_align_endio;
3889         align_bi->bi_private = raid_bio;
3890         /*
3891          *      compute position
3892          */
3893         align_bi->bi_sector =  raid5_compute_sector(conf, raid_bio->bi_sector,
3894                                                     0,
3895                                                     &dd_idx, NULL);
3896 
3897         rcu_read_lock();
3898         rdev = rcu_dereference(conf->disks[dd_idx].rdev);
3899         if (rdev && test_bit(In_sync, &rdev->flags)) {
3900                 atomic_inc(&rdev->nr_pending);
3901                 rcu_read_unlock();
3902                 raid_bio->bi_next = (void*)rdev;
3903                 align_bi->bi_bdev =  rdev->bdev;
3904                 align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
3905                 align_bi->bi_sector += rdev->data_offset;
3906 
3907                 if (!bio_fits_rdev(align_bi)) {
3908                         /* too big in some way */
3909                         bio_put(align_bi);
3910                         rdev_dec_pending(rdev, mddev);
3911                         return 0;
3912                 }
3913 
3914                 spin_lock_irq(&conf->device_lock);
3915                 wait_event_lock_irq(conf->wait_for_stripe,
3916                                     conf->quiesce == 0,
3917                                     conf->device_lock, /* nothing */);
3918                 atomic_inc(&conf->active_aligned_reads);
3919                 spin_unlock_irq(&conf->device_lock);
3920 
3921                 generic_make_request(align_bi);
3922                 return 1;
3923         } else {
3924                 rcu_read_unlock();
3925                 bio_put(align_bi);
3926                 return 0;
3927         }
3928 }
3929 
3930 /* __get_priority_stripe - get the next stripe to process
3931  *
3932  * Full stripe writes are allowed to pass preread active stripes up until
3933  * the bypass_threshold is exceeded.  In general the bypass_count
3934  * increments when the handle_list is handled before the hold_list; however, it
3935  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
3936  * stripe with in flight i/o.  The bypass_count will be reset when the
3937  * head of the hold_list has changed, i.e. the head was promoted to the
3938  * handle_list.
3939  */
3940 static struct stripe_head *__get_priority_stripe(raid5_conf_t *conf)
3941 {
3942         struct stripe_head *sh;
3943 
3944         pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
3945                   __func__,
3946                   list_empty(&conf->handle_list) ? "empty" : "busy",
3947                   list_empty(&conf->hold_list) ? "empty" : "busy",
3948                   atomic_read(&conf->pending_full_writes), conf->bypass_count);
3949 
3950         if (!list_empty(&conf->handle_list)) {
3951                 sh = list_entry(conf->handle_list.next, typeof(*sh), lru);
3952 
3953                 if (list_empty(&conf->hold_list))
3954                         conf->bypass_count = 0;
3955                 else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
3956                         if (conf->hold_list.next == conf->last_hold)
3957                                 conf->bypass_count++;
3958                         else {
3959                                 conf->last_hold = conf->hold_list.next;
3960                                 conf->bypass_count -= conf->bypass_threshold;
3961                                 if (conf->bypass_count < 0)
3962                                         conf->bypass_count = 0;
3963                         }
3964                 }
3965         } else if (!list_empty(&conf->hold_list) &&
3966                    ((conf->bypass_threshold &&
3967                      conf->bypass_count > conf->bypass_threshold) ||
3968                     atomic_read(&conf->pending_full_writes) == 0)) {
3969                 sh = list_entry(conf->hold_list.next,
3970                                 typeof(*sh), lru);
3971                 conf->bypass_count -= conf->bypass_threshold;
3972                 if (conf->bypass_count < 0)
3973                         conf->bypass_count = 0;
3974         } else
3975                 return NULL;
3976 
3977         list_del_init(&sh->lru);
3978         atomic_inc(&sh->count);
3979         BUG_ON(atomic_read(&sh->count) != 1);
3980         return sh;
3981 }
3982 
3983 static int make_request(mddev_t *mddev, struct bio * bi)
3984 {
3985         raid5_conf_t *conf = mddev->private;
3986         int dd_idx;
3987         sector_t new_sector;
3988         sector_t logical_sector, last_sector;
3989         struct stripe_head *sh;
3990         const int rw = bio_data_dir(bi);
3991         int remaining;
3992 
3993         if (unlikely(bi->bi_rw & REQ_FLUSH)) {
3994                 md_flush_request(mddev, bi);
3995                 return 0;
3996         }
3997 
3998         md_write_start(mddev, bi);
3999 
4000         if (rw == READ &&
4001              mddev->reshape_position == MaxSector &&
4002              chunk_aligned_read(mddev,bi))
4003                 return 0;
4004 
4005         logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4006         last_sector = bi->bi_sector + (bi->bi_size>>9);
4007         bi->bi_next = NULL;
4008         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
4009 
4010         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
4011                 DEFINE_WAIT(w);
4012                 int disks, data_disks;
4013                 int previous;
4014 
4015         retry:
4016                 previous = 0;
4017                 disks = conf->raid_disks;
4018                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
4019                 if (unlikely(conf->reshape_progress != MaxSector)) {
4020                         /* spinlock is needed as reshape_progress may be
4021                          * 64bit on a 32bit platform, and so it might be
4022                          * possible to see a half-updated value
4023                          * Ofcourse reshape_progress could change after
4024                          * the lock is dropped, so once we get a reference
4025                          * to the stripe that we think it is, we will have
4026                          * to check again.
4027                          */
4028                         spin_lock_irq(&conf->device_lock);
4029                         if (mddev->delta_disks < 0
4030                             ? logical_sector < conf->reshape_progress
4031                             : logical_sector >= conf->reshape_progress) {
4032                                 disks = conf->previous_raid_disks;
4033                                 previous = 1;
4034                         } else {
4035                                 if (mddev->delta_disks < 0
4036                                     ? logical_sector < conf->reshape_safe
4037                                     : logical_sector >= conf->reshape_safe) {
4038                                         spin_unlock_irq(&conf->device_lock);
4039                                         schedule();
4040                                         goto retry;
4041                                 }
4042                         }
4043                         spin_unlock_irq(&conf->device_lock);
4044                 }
4045                 data_disks = disks - conf->max_degraded;
4046 
4047                 new_sector = raid5_compute_sector(conf, logical_sector,
4048                                                   previous,
4049                                                   &dd_idx, NULL);
4050                 pr_debug("raid456: make_request, sector %llu logical %llu\n",
4051                         (unsigned long long)new_sector, 
4052                         (unsigned long long)logical_sector);
4053 
4054                 sh = get_active_stripe(conf, new_sector, previous,
4055                                        (bi->bi_rw&RWA_MASK), 0);
4056                 if (sh) {
4057                         if (unlikely(previous)) {
4058                                 /* expansion might have moved on while waiting for a
4059                                  * stripe, so we must do the range check again.
4060                                  * Expansion could still move past after this
4061                                  * test, but as we are holding a reference to
4062                                  * 'sh', we know that if that happens,
4063                                  *  STRIPE_EXPANDING will get set and the expansion
4064                                  * won't proceed until we finish with the stripe.
4065                                  */
4066                                 int must_retry = 0;
4067                                 spin_lock_irq(&conf->device_lock);
4068                                 if (mddev->delta_disks < 0
4069                                     ? logical_sector >= conf->reshape_progress
4070                                     : logical_sector < conf->reshape_progress)
4071                                         /* mismatch, need to try again */
4072                                         must_retry = 1;
4073                                 spin_unlock_irq(&conf->device_lock);
4074                                 if (must_retry) {
4075                                         release_stripe(sh);
4076                                         schedule();
4077                                         goto retry;
4078                                 }
4079                         }
4080 
4081                         if (bio_data_dir(bi) == WRITE &&
4082                             logical_sector >= mddev->suspend_lo &&
4083                             logical_sector < mddev->suspend_hi) {
4084                                 release_stripe(sh);
4085                                 /* As the suspend_* range is controlled by
4086                                  * userspace, we want an interruptible
4087                                  * wait.
4088                                  */
4089                                 flush_signals(current);
4090                                 prepare_to_wait(&conf->wait_for_overlap,
4091                                                 &w, TASK_INTERRUPTIBLE);
4092                                 if (logical_sector >= mddev->suspend_lo &&
4093                                     logical_sector < mddev->suspend_hi)
4094                                         schedule();
4095                                 goto retry;
4096                         }
4097 
4098                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
4099                             !add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
4100                                 /* Stripe is busy expanding or
4101                                  * add failed due to overlap.  Flush everything
4102                                  * and wait a while
4103                                  */
4104                                 md_raid5_unplug_device(conf);
4105                                 release_stripe(sh);
4106                                 schedule();
4107                                 goto retry;
4108                         }
4109                         finish_wait(&conf->wait_for_overlap, &w);
4110                         set_bit(STRIPE_HANDLE, &sh->state);
4111                         clear_bit(STRIPE_DELAYED, &sh->state);
4112                         if ((bi->bi_rw & REQ_SYNC) &&
4113                             !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4114                                 atomic_inc(&conf->preread_active_stripes);
4115                         release_stripe(sh);
4116                 } else {
4117                         /* cannot get stripe for read-ahead, just give-up */
4118                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
4119                         finish_wait(&conf->wait_for_overlap, &w);
4120                         break;
4121                 }
4122                         
4123         }
4124         spin_lock_irq(&conf->device_lock);
4125         remaining = raid5_dec_bi_phys_segments(bi);
4126         spin_unlock_irq(&conf->device_lock);
4127         if (remaining == 0) {
4128 
4129                 if ( rw == WRITE )
4130                         md_write_end(mddev);
4131 
4132                 bio_endio(bi, 0);
4133         }
4134 
4135         return 0;
4136 }
4137 
4138 static sector_t raid5_size(mddev_t *mddev, sector_t sectors, int raid_disks);
4139 
4140 static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped)
4141 {
4142         /* reshaping is quite different to recovery/resync so it is
4143          * handled quite separately ... here.
4144          *
4145          * On each call to sync_request, we gather one chunk worth of
4146          * destination stripes and flag them as expanding.
4147          * Then we find all the source stripes and request reads.
4148          * As the reads complete, handle_stripe will copy the data
4149          * into the destination stripe and release that stripe.
4150          */
4151         raid5_conf_t *conf = mddev->private;
4152         struct stripe_head *sh;
4153         sector_t first_sector, last_sector;
4154         int raid_disks = conf->previous_raid_disks;
4155         int data_disks = raid_disks - conf->max_degraded;
4156         int new_data_disks = conf->raid_disks - conf->max_degraded;
4157         int i;
4158         int dd_idx;
4159         sector_t writepos, readpos, safepos;
4160         sector_t stripe_addr;
4161         int reshape_sectors;
4162         struct list_head stripes;
4163 
4164         if (sector_nr == 0) {
4165                 /* If restarting in the middle, skip the initial sectors */
4166                 if (mddev->delta_disks < 0 &&
4167                     conf->reshape_progress < raid5_size(mddev, 0, 0)) {
4168                         sector_nr = raid5_size(mddev, 0, 0)
4169                                 - conf->reshape_progress;
4170                 } else if (mddev->delta_disks >= 0 &&
4171                            conf->reshape_progress > 0)
4172                         sector_nr = conf->reshape_progress;
4173                 sector_div(sector_nr, new_data_disks);
4174                 if (sector_nr) {
4175                         mddev->curr_resync_completed = sector_nr;
4176                         sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4177                         *skipped = 1;
4178                         return sector_nr;
4179                 }
4180         }
4181 
4182         /* We need to process a full chunk at a time.
4183          * If old and new chunk sizes differ, we need to process the
4184          * largest of these
4185          */
4186         if (mddev->new_chunk_sectors > mddev->chunk_sectors)
4187                 reshape_sectors = mddev->new_chunk_sectors;
4188         else
4189                 reshape_sectors = mddev->chunk_sectors;
4190 
4191         /* we update the metadata when there is more than 3Meg
4192          * in the block range (that is rather arbitrary, should
4193          * probably be time based) or when the data about to be
4194          * copied would over-write the source of the data at
4195          * the front of the range.
4196          * i.e. one new_stripe along from reshape_progress new_maps
4197          * to after where reshape_safe old_maps to
4198          */
4199         writepos = conf->reshape_progress;
4200         sector_div(writepos, new_data_disks);
4201         readpos = conf->reshape_progress;
4202         sector_div(readpos, data_disks);
4203         safepos = conf->reshape_safe;
4204         sector_div(safepos, data_disks);
4205         if (mddev->delta_disks < 0) {
4206                 writepos -= min_t(sector_t, reshape_sectors, writepos);
4207                 readpos += reshape_sectors;
4208                 safepos += reshape_sectors;
4209         } else {
4210                 writepos += reshape_sectors;
4211                 readpos -= min_t(sector_t, reshape_sectors, readpos);
4212                 safepos -= min_t(sector_t, reshape_sectors, safepos);
4213         }
4214 
4215         /* 'writepos' is the most advanced device address we might write.
4216          * 'readpos' is the least advanced device address we might read.
4217          * 'safepos' is the least address recorded in the metadata as having
4218          *     been reshaped.
4219          * If 'readpos' is behind 'writepos', then there is no way that we can
4220          * ensure safety in the face of a crash - that must be done by userspace
4221          * making a backup of the data.  So in that case there is no particular
4222          * rush to update metadata.
4223          * Otherwise if 'safepos' is behind 'writepos', then we really need to
4224          * update the metadata to advance 'safepos' to match 'readpos' so that
4225          * we can be safe in the event of a crash.
4226          * So we insist on updating metadata if safepos is behind writepos and
4227          * readpos is beyond writepos.
4228          * In any case, update the metadata every 10 seconds.
4229          * Maybe that number should be configurable, but I'm not sure it is
4230          * worth it.... maybe it could be a multiple of safemode_delay???
4231          */
4232         if ((mddev->delta_disks < 0
4233              ? (safepos > writepos && readpos < writepos)
4234              : (safepos < writepos && readpos > writepos)) ||
4235             time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
4236                 /* Cannot proceed until we've updated the superblock... */
4237                 wait_event(conf->wait_for_overlap,
4238                            atomic_read(&conf->reshape_stripes)==0);
4239                 mddev->reshape_position = conf->reshape_progress;
4240                 mddev->curr_resync_completed = mddev->curr_resync;
4241                 conf->reshape_checkpoint = jiffies;
4242                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
4243                 md_wakeup_thread(mddev->thread);
4244                 wait_event(mddev->sb_wait, mddev->flags == 0 ||
4245                            kthread_should_stop());
4246                 spin_lock_irq(&conf->device_lock);
4247                 conf->reshape_safe = mddev->reshape_position;
4248                 spin_unlock_irq(&conf->device_lock);
4249                 wake_up(&conf->wait_for_overlap);
4250                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4251         }
4252 
4253         if (mddev->delta_disks < 0) {
4254                 BUG_ON(conf->reshape_progress == 0);
4255                 stripe_addr = writepos;
4256                 BUG_ON((mddev->dev_sectors &
4257                         ~((sector_t)reshape_sectors - 1))
4258                        - reshape_sectors - stripe_addr
4259                        != sector_nr);
4260         } else {
4261                 BUG_ON(writepos != sector_nr + reshape_sectors);
4262                 stripe_addr = sector_nr;
4263         }
4264         INIT_LIST_HEAD(&stripes);
4265         for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
4266                 int j;
4267                 int skipped_disk = 0;
4268                 sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
4269                 set_bit(STRIPE_EXPANDING, &sh->state);
4270                 atomic_inc(&conf->reshape_stripes);
4271                 /* If any of this stripe is beyond the end of the old
4272                  * array, then we need to zero those blocks
4273                  */
4274                 for (j=sh->disks; j--;) {
4275                         sector_t s;
4276                         if (j == sh->pd_idx)
4277                                 continue;
4278                         if (conf->level == 6 &&
4279                             j == sh->qd_idx)
4280                                 continue;
4281                         s = compute_blocknr(sh, j, 0);
4282                         if (s < raid5_size(mddev, 0, 0)) {
4283                                 skipped_disk = 1;
4284                                 continue;
4285                         }
4286                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
4287                         set_bit(R5_Expanded, &sh->dev[j].flags);
4288                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
4289                 }
4290                 if (!skipped_disk) {
4291                         set_bit(STRIPE_EXPAND_READY, &sh->state);
4292                         set_bit(STRIPE_HANDLE, &sh->state);
4293                 }
4294                 list_add(&sh->lru, &stripes);
4295         }
4296         spin_lock_irq(&conf->device_lock);
4297         if (mddev->delta_disks < 0)
4298                 conf->reshape_progress -= reshape_sectors * new_data_disks;
4299         else
4300                 conf->reshape_progress += reshape_sectors * new_data_disks;
4301         spin_unlock_irq(&conf->device_lock);
4302         /* Ok, those stripe are ready. We can start scheduling
4303          * reads on the source stripes.
4304          * The source stripes are determined by mapping the first and last
4305          * block on the destination stripes.
4306          */
4307         first_sector =
4308                 raid5_compute_sector(conf, stripe_addr*(new_data_disks),
4309                                      1, &dd_idx, NULL);
4310         last_sector =
4311                 raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
4312                                             * new_data_disks - 1),
4313                                      1, &dd_idx, NULL);
4314         if (last_sector >= mddev->dev_sectors)
4315                 last_sector = mddev->dev_sectors - 1;
4316         while (first_sector <= last_sector) {
4317                 sh = get_active_stripe(conf, first_sector, 1, 0, 1);
4318                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4319                 set_bit(STRIPE_HANDLE, &sh->state);
4320                 release_stripe(sh);
4321                 first_sector += STRIPE_SECTORS;
4322         }
4323         /* Now that the sources are clearly marked, we can release
4324          * the destination stripes
4325          */
4326         while (!list_empty(&stripes)) {
4327                 sh = list_entry(stripes.next, struct stripe_head, lru);
4328                 list_del_init(&sh->lru);
4329                 release_stripe(sh);
4330         }
4331         /* If this takes us to the resync_max point where we have to pause,
4332          * then we need to write out the superblock.
4333          */
4334         sector_nr += reshape_sectors;
4335         if ((sector_nr - mddev->curr_resync_completed) * 2
4336             >= mddev->resync_max - mddev->curr_resync_completed) {
4337                 /* Cannot proceed until we've updated the superblock... */
4338                 wait_event(conf->wait_for_overlap,
4339                            atomic_read(&conf->reshape_stripes) == 0);
4340                 mddev->reshape_position = conf->reshape_progress;
4341                 mddev->curr_resync_completed = mddev->curr_resync + reshape_sectors;
4342                 conf->reshape_checkpoint = jiffies;
4343                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
4344                 md_wakeup_thread(mddev->thread);
4345                 wait_event(mddev->sb_wait,
4346                            !test_bit(MD_CHANGE_DEVS, &mddev->flags)
4347                            || kthread_should_stop());
4348                 spin_lock_irq(&conf->device_lock);
4349                 conf->reshape_safe = mddev->reshape_position;
4350                 spin_unlock_irq(&conf->device_lock);
4351                 wake_up(&conf->wait_for_overlap);
4352                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4353         }
4354         return reshape_sectors;
4355 }
4356 
4357 /* FIXME go_faster isn't used */
4358 static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
4359 {
4360         raid5_conf_t *conf = mddev->private;
4361         struct stripe_head *sh;
4362         sector_t max_sector = mddev->dev_sectors;
4363         sector_t sync_blocks;
4364         int still_degraded = 0;
4365         int i;
4366 
4367         if (sector_nr >= max_sector) {
4368                 /* just being told to finish up .. nothing much to do */
4369                 unplug_slaves(mddev);
4370 
4371                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
4372                         end_reshape(conf);
4373                         return 0;
4374                 }
4375 
4376                 if (mddev->curr_resync < max_sector) /* aborted */
4377                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
4378                                         &sync_blocks, 1);
4379                 else /* completed sync */
4380                         conf->fullsync = 0;
4381                 bitmap_close_sync(mddev->bitmap);
4382 
4383                 return 0;
4384         }
4385 
4386         /* Allow raid5_quiesce to complete */
4387         wait_event(conf->wait_for_overlap, conf->quiesce != 2);
4388 
4389         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
4390                 return reshape_request(mddev, sector_nr, skipped);
4391 
4392         /* No need to check resync_max as we never do more than one
4393          * stripe, and as resync_max will always be on a chunk boundary,
4394          * if the check in md_do_sync didn't fire, there is no chance
4395          * of overstepping resync_max here
4396          */
4397 
4398         /* if there is too many failed drives and we are trying
4399          * to resync, then assert that we are finished, because there is
4400          * nothing we can do.
4401          */
4402         if (mddev->degraded >= conf->max_degraded &&
4403             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
4404                 sector_t rv = mddev->dev_sectors - sector_nr;
4405                 *skipped = 1;
4406                 return rv;
4407         }
4408         if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
4409             !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
4410             !conf->fullsync && sync_blocks >= STRIPE_SECTORS) {
4411                 /* we can skip this block, and probably more */
4412                 sync_blocks /= STRIPE_SECTORS;
4413                 *skipped = 1;
4414                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
4415         }
4416 
4417 
4418         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
4419 
4420         sh = get_active_stripe(conf, sector_nr, 0, 1, 0);
4421         if (sh == NULL) {
4422                 sh = get_active_stripe(conf, sector_nr, 0, 0, 0);
4423                 /* make sure we don't swamp the stripe cache if someone else
4424                  * is trying to get access
4425                  */
4426                 schedule_timeout_uninterruptible(1);
4427         }
4428         /* Need to check if array will still be degraded after recovery/resync
4429          * We don't need to check the 'failed' flag as when that gets set,
4430          * recovery aborts.
4431          */
4432         for (i = 0; i < conf->raid_disks; i++)
4433                 if (conf->disks[i].rdev == NULL)
4434                         still_degraded = 1;
4435 
4436         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
4437 
4438         spin_lock(&sh->lock);
4439         set_bit(STRIPE_SYNCING, &sh->state);
4440         clear_bit(STRIPE_INSYNC, &sh->state);
4441         spin_unlock(&sh->lock);
4442 
4443         handle_stripe(sh);
4444         release_stripe(sh);
4445 
4446         return STRIPE_SECTORS;
4447 }
4448 
4449 static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
4450 {
4451         /* We may not be able to submit a whole bio at once as there
4452          * may not be enough stripe_heads available.
4453          * We cannot pre-allocate enough stripe_heads as we may need
4454          * more than exist in the cache (if we allow ever large chunks).
4455          * So we do one stripe head at a time and record in
4456          * ->bi_hw_segments how many have been done.
4457          *
4458          * We *know* that this entire raid_bio is in one chunk, so
4459          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
4460          */
4461         struct stripe_head *sh;
4462         int dd_idx;
4463         sector_t sector, logical_sector, last_sector;
4464         int scnt = 0;
4465         int remaining;
4466         int handled = 0;
4467 
4468         logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4469         sector = raid5_compute_sector(conf, logical_sector,
4470                                       0, &dd_idx, NULL);
4471         last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
4472 
4473         for (; logical_sector < last_sector;
4474              logical_sector += STRIPE_SECTORS,
4475                      sector += STRIPE_SECTORS,
4476                      scnt++) {
4477 
4478                 if (scnt < raid5_bi_hw_segments(raid_bio))
4479                         /* already done this stripe */
4480                         continue;
4481 
4482                 sh = get_active_stripe(conf, sector, 0, 1, 0);
4483 
4484                 if (!sh) {
4485                         /* failed to get a stripe - must wait */
4486                         raid5_set_bi_hw_segments(raid_bio, scnt);
4487                         conf->retry_read_aligned = raid_bio;
4488                         return handled;
4489                 }
4490 
4491                 set_bit(R5_ReadError, &sh->dev[dd_idx].flags);
4492                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
4493                         release_stripe(sh);
4494                         raid5_set_bi_hw_segments(raid_bio, scnt);
4495                         conf->retry_read_aligned = raid_bio;
4496                         return handled;
4497                 }
4498 
4499                 handle_stripe(sh);
4500                 release_stripe(sh);
4501                 handled++;
4502         }
4503         spin_lock_irq(&conf->device_lock);
4504         remaining = raid5_dec_bi_phys_segments(raid_bio);
4505         spin_unlock_irq(&conf->device_lock);
4506         if (remaining == 0)
4507                 bio_endio(raid_bio, 0);
4508         if (atomic_dec_and_test(&conf->active_aligned_reads))
4509                 wake_up(&conf->wait_for_stripe);
4510         return handled;
4511 }
4512 
4513 
4514 /*
4515  * This is our raid5 kernel thread.
4516  *
4517  * We scan the hash table for stripes which can be handled now.
4518  * During the scan, completed stripes are saved for us by the interrupt
4519  * handler, so that they will not have to wait for our next wakeup.
4520  */
4521 static void raid5d(mddev_t *mddev)
4522 {
4523         struct stripe_head *sh;
4524         raid5_conf_t *conf = mddev->private;
4525         int handled;
4526 
4527         pr_debug("+++ raid5d active\n");
4528 
4529         md_check_recovery(mddev);
4530 
4531         handled = 0;
4532         spin_lock_irq(&conf->device_lock);
4533         while (1) {
4534                 struct bio *bio;
4535 
4536                 if (conf->seq_flush != conf->seq_write) {
4537                         int seq = conf->seq_flush;
4538                         spin_unlock_irq(&conf->device_lock);
4539                         bitmap_unplug(mddev->bitmap);
4540                         spin_lock_irq(&conf->device_lock);
4541                         conf->seq_write = seq;
4542                         activate_bit_delay(conf);
4543                 }
4544 
4545                 while ((bio = remove_bio_from_retry(conf))) {
4546                         int ok;
4547                         spin_unlock_irq(&conf->device_lock);
4548                         ok = retry_aligned_read(conf, bio);
4549                         spin_lock_irq(&conf->device_lock);
4550                         if (!ok)
4551                                 break;
4552                         handled++;
4553                 }
4554 
4555                 sh = __get_priority_stripe(conf);
4556 
4557                 if (!sh)
4558                         break;
4559                 spin_unlock_irq(&conf->device_lock);
4560                 
4561                 handled++;
4562                 handle_stripe(sh);
4563                 release_stripe(sh);
4564                 cond_resched();
4565 
4566                 spin_lock_irq(&conf->device_lock);
4567         }
4568         pr_debug("%d stripes handled\n", handled);
4569 
4570         spin_unlock_irq(&conf->device_lock);
4571 
4572         async_tx_issue_pending_all();
4573         unplug_slaves(mddev);
4574 
4575         pr_debug("--- raid5d inactive\n");
4576 }
4577 
4578 static ssize_t
4579 raid5_show_stripe_cache_size(mddev_t *mddev, char *page)
4580 {
4581         raid5_conf_t *conf = mddev->private;
4582         if (conf)
4583                 return sprintf(page, "%d\n", conf->max_nr_stripes);
4584         else
4585                 return 0;
4586 }
4587 
4588 int
4589 raid5_set_cache_size(mddev_t *mddev, int size)
4590 {
4591         raid5_conf_t *conf = mddev->private;
4592         int err;
4593 
4594         if (size <= 16 || size > 32768)
4595                 return -EINVAL;
4596         while (size < conf->max_nr_stripes) {
4597                 if (drop_one_stripe(conf))
4598                         conf->max_nr_stripes--;
4599                 else
4600                         break;
4601         }
4602         err = md_allow_write(mddev);
4603         if (err)
4604                 return err;
4605         while (size > conf->max_nr_stripes) {
4606                 if (grow_one_stripe(conf))
4607                         conf->max_nr_stripes++;
4608                 else break;
4609         }
4610         return 0;
4611 }
4612 EXPORT_SYMBOL(raid5_set_cache_size);
4613 
4614 static ssize_t
4615 raid5_store_stripe_cache_size(mddev_t *mddev, const char *page, size_t len)
4616 {
4617         raid5_conf_t *conf = mddev->private;
4618         unsigned long new;
4619         int err;
4620 
4621         if (len >= PAGE_SIZE)
4622                 return -EINVAL;
4623         if (!conf)
4624                 return -ENODEV;
4625 
4626         if (strict_strtoul(page, 10, &new))
4627                 return -EINVAL;
4628         err = raid5_set_cache_size(mddev, new);
4629         if (err)
4630                 return err;
4631         return len;
4632 }
4633 
4634 static struct md_sysfs_entry
4635 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
4636                                 raid5_show_stripe_cache_size,
4637                                 raid5_store_stripe_cache_size);
4638 
4639 static ssize_t
4640 raid5_show_preread_threshold(mddev_t *mddev, char *page)
4641 {
4642         raid5_conf_t *conf = mddev->private;
4643         if (conf)
4644                 return sprintf(page, "%d\n", conf->bypass_threshold);
4645         else
4646                 return 0;
4647 }
4648 
4649 static ssize_t
4650 raid5_store_preread_threshold(mddev_t *mddev, const char *page, size_t len)
4651 {
4652         raid5_conf_t *conf = mddev->private;
4653         unsigned long new;
4654         if (len >= PAGE_SIZE)
4655                 return -EINVAL;
4656         if (!conf)
4657                 return -ENODEV;
4658 
4659         if (strict_strtoul(page, 10, &new))
4660                 return -EINVAL;
4661         if (new > conf->max_nr_stripes)
4662                 return -EINVAL;
4663         conf->bypass_threshold = new;
4664         return len;
4665 }
4666 
4667 static struct md_sysfs_entry
4668 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
4669                                         S_IRUGO | S_IWUSR,
4670                                         raid5_show_preread_threshold,
4671                                         raid5_store_preread_threshold);
4672 
4673 static ssize_t
4674 stripe_cache_active_show(mddev_t *mddev, char *page)
4675 {
4676         raid5_conf_t *conf = mddev->private;
4677         if (conf)
4678                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
4679         else
4680                 return 0;
4681 }
4682 
4683 static struct md_sysfs_entry
4684 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
4685 
4686 static struct attribute *raid5_attrs[] =  {
4687         &raid5_stripecache_size.attr,
4688         &raid5_stripecache_active.attr,
4689         &raid5_preread_bypass_threshold.attr,
4690         NULL,
4691 };
4692 static struct attribute_group raid5_attrs_group = {
4693         .name = NULL,
4694         .attrs = raid5_attrs,
4695 };
4696 
4697 static sector_t
4698 raid5_size(mddev_t *mddev, sector_t sectors, int raid_disks)
4699 {
4700         raid5_conf_t *conf = mddev->private;
4701 
4702         if (!sectors)
4703                 sectors = mddev->dev_sectors;
4704         if (!raid_disks)
4705                 /* size is defined by the smallest of previous and new size */
4706                 raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
4707 
4708         sectors &= ~((sector_t)mddev->chunk_sectors - 1);
4709         sectors &= ~((sector_t)mddev->new_chunk_sectors - 1);
4710         return sectors * (raid_disks - conf->max_degraded);
4711 }
4712 
4713 static void raid5_free_percpu(raid5_conf_t *conf)
4714 {
4715         struct raid5_percpu *percpu;
4716         unsigned long cpu;
4717 
4718         if (!conf->percpu)
4719                 return;
4720 
4721         get_online_cpus();
4722         for_each_possible_cpu(cpu) {
4723                 percpu = per_cpu_ptr(conf->percpu, cpu);
4724                 safe_put_page(percpu->spare_page);
4725                 kfree(percpu->scribble);
4726         }
4727 #ifdef CONFIG_HOTPLUG_CPU
4728         unregister_cpu_notifier(&conf->cpu_notify);
4729 #endif
4730         put_online_cpus();
4731 
4732         free_percpu(conf->percpu);
4733 }
4734 
4735 static void free_conf(raid5_conf_t *conf)
4736 {
4737         shrink_stripes(conf);
4738         raid5_free_percpu(conf);
4739         kfree(conf->disks);
4740         kfree(conf->stripe_hashtbl);
4741         kfree(conf);
4742 }
4743 
4744 #ifdef CONFIG_HOTPLUG_CPU
4745 static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
4746                               void *hcpu)
4747 {
4748         raid5_conf_t *conf = container_of(nfb, raid5_conf_t, cpu_notify);
4749         long cpu = (long)hcpu;
4750         struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
4751 
4752         switch (action) {
4753         case CPU_UP_PREPARE:
4754         case CPU_UP_PREPARE_FROZEN:
4755                 if (conf->level == 6 && !percpu->spare_page)
4756                         percpu->spare_page = alloc_page(GFP_KERNEL);
4757                 if (!percpu->scribble)
4758                         percpu->scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
4759 
4760                 if (!percpu->scribble ||
4761                     (conf->level == 6 && !percpu->spare_page)) {
4762                         safe_put_page(percpu->spare_page);
4763                         kfree(percpu->scribble);
4764                         pr_err("%s: failed memory allocation for cpu%ld\n",
4765                                __func__, cpu);
4766                         return notifier_from_errno(-ENOMEM);
4767                 }
4768                 break;
4769         case CPU_DEAD:
4770         case CPU_DEAD_FROZEN:
4771                 safe_put_page(percpu->spare_page);
4772                 kfree(percpu->scribble);
4773                 percpu->spare_page = NULL;
4774                 percpu->scribble = NULL;
4775                 break;
4776         default:
4777                 break;
4778         }
4779         return NOTIFY_OK;
4780 }
4781 #endif
4782 
4783 static int raid5_alloc_percpu(raid5_conf_t *conf)
4784 {
4785         unsigned long cpu;
4786         struct page *spare_page;
4787         struct raid5_percpu __percpu *allcpus;
4788         void *scribble;
4789         int err;
4790 
4791         allcpus = alloc_percpu(struct raid5_percpu);
4792         if (!allcpus)
4793                 return -ENOMEM;
4794         conf->percpu = allcpus;
4795 
4796         get_online_cpus();
4797         err = 0;
4798         for_each_present_cpu(cpu) {
4799                 if (conf->level == 6) {
4800                         spare_page = alloc_page(GFP_KERNEL);
4801                         if (!spare_page) {
4802                                 err = -ENOMEM;
4803                                 break;
4804                         }
4805                         per_cpu_ptr(conf->percpu, cpu)->spare_page = spare_page;
4806                 }
4807                 scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
4808                 if (!scribble) {
4809                         err = -ENOMEM;
4810                         break;
4811                 }
4812                 per_cpu_ptr(conf->percpu, cpu)->scribble = scribble;
4813         }
4814 #ifdef CONFIG_HOTPLUG_CPU
4815         conf->cpu_notify.notifier_call = raid456_cpu_notify;
4816         conf->cpu_notify.priority = 0;
4817         if (err == 0)
4818                 err = register_cpu_notifier(&conf->cpu_notify);
4819 #endif
4820         put_online_cpus();
4821 
4822         return err;
4823 }
4824 
4825 static raid5_conf_t *setup_conf(mddev_t *mddev)
4826 {
4827         raid5_conf_t *conf;
4828         int raid_disk, memory, max_disks;
4829         mdk_rdev_t *rdev;
4830         struct disk_info *disk;
4831 
4832         if (mddev->new_level != 5
4833             && mddev->new_level != 4
4834             && mddev->new_level != 6) {
4835                 printk(KERN_ERR "md/raid:%s: raid level not set to 4/5/6 (%d)\n",
4836                        mdname(mddev), mddev->new_level);
4837                 return ERR_PTR(-EIO);
4838         }
4839         if ((mddev->new_level == 5
4840              && !algorithm_valid_raid5(mddev->new_layout)) ||
4841             (mddev->new_level == 6
4842              && !algorithm_valid_raid6(mddev->new_layout))) {
4843                 printk(KERN_ERR "md/raid:%s: layout %d not supported\n",
4844                        mdname(mddev), mddev->new_layout);
4845                 return ERR_PTR(-EIO);
4846         }
4847         if (mddev->new_level == 6 && mddev->raid_disks < 4) {
4848                 printk(KERN_ERR "md/raid:%s: not enough configured devices (%d, minimum 4)\n",
4849                        mdname(mddev), mddev->raid_disks);
4850                 return ERR_PTR(-EINVAL);
4851         }
4852 
4853         if (!mddev->new_chunk_sectors ||
4854             (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
4855             !is_power_of_2(mddev->new_chunk_sectors)) {
4856                 printk(KERN_ERR "md/raid:%s: invalid chunk size %d\n",
4857                        mdname(mddev), mddev->new_chunk_sectors << 9);
4858                 return ERR_PTR(-EINVAL);
4859         }
4860 
4861         conf = kzalloc(sizeof(raid5_conf_t), GFP_KERNEL);
4862         if (conf == NULL)
4863                 goto abort;
4864         spin_lock_init(&conf->device_lock);
4865         init_waitqueue_head(&conf->wait_for_stripe);
4866         init_waitqueue_head(&conf->wait_for_overlap);
4867         INIT_LIST_HEAD(&conf->handle_list);
4868         INIT_LIST_HEAD(&conf->hold_list);
4869         INIT_LIST_HEAD(&conf->delayed_list);
4870         INIT_LIST_HEAD(&conf->bitmap_list);
4871         INIT_LIST_HEAD(&conf->inactive_list);
4872         atomic_set(&conf->active_stripes, 0);
4873         atomic_set(&conf->preread_active_stripes, 0);
4874         atomic_set(&conf->active_aligned_reads, 0);
4875         conf->bypass_threshold = BYPASS_THRESHOLD;
4876 
4877         conf->raid_disks = mddev->raid_disks;
4878         if (mddev->reshape_position == MaxSector)
4879                 conf->previous_raid_disks = mddev->raid_disks;
4880         else
4881                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
4882         max_disks = max(conf->raid_disks, conf->previous_raid_disks);
4883         conf->scribble_len = scribble_len(max_disks);
4884 
4885         conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
4886                               GFP_KERNEL);
4887         if (!conf->disks)
4888                 goto abort;
4889 
4890         conf->mddev = mddev;
4891 
4892         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
4893                 goto abort;
4894 
4895         conf->level = mddev->new_level;
4896         if (raid5_alloc_percpu(conf) != 0)
4897                 goto abort;
4898 
4899         pr_debug("raid456: run(%s) called.\n", mdname(mddev));
4900 
4901         list_for_each_entry(rdev, &mddev->disks, same_set) {
4902                 raid_disk = rdev->raid_disk;
4903                 if (raid_disk >= max_disks
4904                     || raid_disk < 0)
4905                         continue;
4906                 disk = conf->disks + raid_disk;
4907 
4908                 disk->rdev = rdev;
4909 
4910                 if (test_bit(In_sync, &rdev->flags)) {
4911                         char b[BDEVNAME_SIZE];
4912                         printk(KERN_INFO "md/raid:%s: device %s operational as raid"
4913                                " disk %d\n",
4914                                mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
4915                 } else
4916                         /* Cannot rely on bitmap to complete recovery */
4917                         conf->fullsync = 1;
4918         }
4919 
4920         conf->chunk_sectors = mddev->new_chunk_sectors;
4921         conf->level = mddev->new_level;
4922         if (conf->level == 6)
4923                 conf->max_degraded = 2;
4924         else
4925                 conf->max_degraded = 1;
4926         conf->algorithm = mddev->new_layout;
4927         conf->max_nr_stripes = NR_STRIPES;
4928         conf->reshape_progress = mddev->reshape_position;
4929         if (conf->reshape_progress != MaxSector) {
4930                 conf->prev_chunk_sectors = mddev->chunk_sectors;
4931                 conf->prev_algo = mddev->layout;
4932         }
4933 
4934         memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
4935                  max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
4936         if (grow_stripes(conf, conf->max_nr_stripes)) {
4937                 printk(KERN_ERR
4938                        "md/raid:%s: couldn't allocate %dkB for buffers\n",
4939                        mdname(mddev), memory);
4940                 goto abort;
4941         } else
4942                 printk(KERN_INFO "md/raid:%s: allocated %dkB\n",
4943                        mdname(mddev), memory);
4944 
4945         conf->thread = md_register_thread(raid5d, mddev, NULL);
4946         if (!conf->thread) {
4947                 printk(KERN_ERR
4948                        "md/raid:%s: couldn't allocate thread.\n",
4949                        mdname(mddev));
4950                 goto abort;
4951         }
4952 
4953         return conf;
4954 
4955  abort:
4956         if (conf) {
4957                 free_conf(conf);
4958                 return ERR_PTR(-EIO);
4959         } else
4960                 return ERR_PTR(-ENOMEM);
4961 }
4962 
4963 
4964 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
4965 {
4966         switch (algo) {
4967         case ALGORITHM_PARITY_0:
4968                 if (raid_disk < max_degraded)
4969                         return 1;
4970                 break;
4971         case ALGORITHM_PARITY_N:
4972                 if (raid_disk >= raid_disks - max_degraded)
4973                         return 1;
4974                 break;
4975         case ALGORITHM_PARITY_0_6:
4976                 if (raid_disk == 0 || 
4977                     raid_disk == raid_disks - 1)
4978                         return 1;
4979                 break;
4980         case ALGORITHM_LEFT_ASYMMETRIC_6:
4981         case ALGORITHM_RIGHT_ASYMMETRIC_6:
4982         case ALGORITHM_LEFT_SYMMETRIC_6:
4983         case ALGORITHM_RIGHT_SYMMETRIC_6:
4984                 if (raid_disk == raid_disks - 1)
4985                         return 1;
4986         }
4987         return 0;
4988 }
4989 
4990 static int run(mddev_t *mddev)
4991 {
4992         raid5_conf_t *conf;
4993         int working_disks = 0;
4994         int dirty_parity_disks = 0;
4995         mdk_rdev_t *rdev;
4996         sector_t reshape_offset = 0;
4997 
4998         if (mddev->recovery_cp != MaxSector)
4999                 printk(KERN_NOTICE "md/raid:%s: not clean"
5000                        " -- starting background reconstruction\n",
5001                        mdname(mddev));
5002         if (mddev->reshape_position != MaxSector) {
5003                 /* Check that we can continue the reshape.
5004                  * Currently only disks can change, it must
5005                  * increase, and we must be past the point where
5006                  * a stripe over-writes itself
5007                  */
5008                 sector_t here_new, here_old;
5009                 int old_disks;
5010                 int max_degraded = (mddev->level == 6 ? 2 : 1);
5011 
5012                 if (mddev->new_level != mddev->level) {
5013                         printk(KERN_ERR "md/raid:%s: unsupported reshape "
5014                                "required - aborting.\n",
5015                                mdname(mddev));
5016                         return -EINVAL;
5017                 }
5018                 old_disks = mddev->raid_disks - mddev->delta_disks;
5019                 /* reshape_position must be on a new-stripe boundary, and one
5020                  * further up in new geometry must map after here in old
5021                  * geometry.
5022                  */
5023                 here_new = mddev->reshape_position;
5024                 if (sector_div(here_new, mddev->new_chunk_sectors *
5025                                (mddev->raid_disks - max_degraded))) {
5026                         printk(KERN_ERR "md/raid:%s: reshape_position not "
5027                                "on a stripe boundary\n", mdname(mddev));
5028                         return -EINVAL;
5029                 }
5030                 reshape_offset = here_new * mddev->new_chunk_sectors;
5031                 /* here_new is the stripe we will write to */
5032                 here_old = mddev->reshape_position;
5033                 sector_div(here_old, mddev->chunk_sectors *
5034                            (old_disks-max_degraded));
5035                 /* here_old is the first stripe that we might need to read
5036                  * from */
5037                 if (mddev->delta_disks == 0) {
5038                         /* We cannot be sure it is safe to start an in-place
5039                          * reshape.  It is only safe if user-space if monitoring
5040                          * and taking constant backups.
5041                          * mdadm always starts a situation like this in
5042                          * readonly mode so it can take control before
5043                          * allowing any writes.  So just check for that.
5044                          */
5045                         if ((here_new * mddev->new_chunk_sectors != 
5046                              here_old * mddev->chunk_sectors) ||
5047                             mddev->ro == 0) {
5048                                 printk(KERN_ERR "md/raid:%s: in-place reshape must be started"
5049                                        " in read-only mode - aborting\n",
5050                                        mdname(mddev));
5051                                 return -EINVAL;
5052                         }
5053                 } else if (mddev->delta_disks < 0
5054                     ? (here_new * mddev->new_chunk_sectors <=
5055                        here_old * mddev->chunk_sectors)
5056                     : (here_new * mddev->new_chunk_sectors >=
5057                        here_old * mddev->chunk_sectors)) {
5058                         /* Reading from the same stripe as writing to - bad */
5059                         printk(KERN_ERR "md/raid:%s: reshape_position too early for "
5060                                "auto-recovery - aborting.\n",
5061                                mdname(mddev));
5062                         return -EINVAL;
5063                 }
5064                 printk(KERN_INFO "md/raid:%s: reshape will continue\n",
5065                        mdname(mddev));
5066                 /* OK, we should be able to continue; */
5067         } else {
5068                 BUG_ON(mddev->level != mddev->new_level);
5069                 BUG_ON(mddev->layout != mddev->new_layout);
5070                 BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
5071                 BUG_ON(mddev->delta_disks != 0);
5072         }
5073 
5074         if (mddev->private == NULL)
5075                 conf = setup_conf(mddev);
5076         else
5077                 conf = mddev->private;
5078 
5079         if (IS_ERR(conf))
5080                 return PTR_ERR(conf);
5081 
5082         mddev->thread = conf->thread;
5083         conf->thread = NULL;
5084         mddev->private = conf;
5085 
5086         /*
5087          * 0 for a fully functional array, 1 or 2 for a degraded array.
5088          */
5089         list_for_each_entry(rdev, &mddev->disks, same_set) {
5090                 if (rdev->raid_disk < 0)
5091                         continue;
5092                 if (test_bit(In_sync, &rdev->flags)) {
5093                         working_disks++;
5094                         continue;
5095                 }
5096                 /* This disc is not fully in-sync.  However if it
5097                  * just stored parity (beyond the recovery_offset),
5098                  * when we don't need to be concerned about the
5099                  * array being dirty.
5100                  * When reshape goes 'backwards', we never have
5101                  * partially completed devices, so we only need
5102                  * to worry about reshape going forwards.
5103                  */
5104                 /* Hack because v0.91 doesn't store recovery_offset properly. */
5105                 if (mddev->major_version == 0 &&
5106                     mddev->minor_version > 90)
5107                         rdev->recovery_offset = reshape_offset;
5108                         
5109                 if (rdev->recovery_offset < reshape_offset) {
5110                         /* We need to check old and new layout */
5111                         if (!only_parity(rdev->raid_disk,
5112                                          conf->algorithm,
5113                                          conf->raid_disks,
5114                                          conf->max_degraded))
5115                                 continue;
5116                 }
5117                 if (!only_parity(rdev->raid_disk,
5118                                  conf->prev_algo,
5119                                  conf->previous_raid_disks,
5120                                  conf->max_degraded))
5121                         continue;
5122                 dirty_parity_disks++;
5123         }
5124 
5125         mddev->degraded = (max(conf->raid_disks, conf->previous_raid_disks)
5126                            - working_disks);
5127 
5128         if (has_failed(conf)) {
5129                 printk(KERN_ERR "md/raid:%s: not enough operational devices"
5130                         " (%d/%d failed)\n",
5131                         mdname(mddev), mddev->degraded, conf->raid_disks);
5132                 goto abort;
5133         }
5134 
5135         /* device size must be a multiple of chunk size */
5136         mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
5137         mddev->resync_max_sectors = mddev->dev_sectors;
5138 
5139         if (mddev->degraded > dirty_parity_disks &&
5140             mddev->recovery_cp != MaxSector) {
5141                 if (mddev->ok_start_degraded)
5142                         printk(KERN_WARNING
5143                                "md/raid:%s: starting dirty degraded array"
5144                                " - data corruption possible.\n",
5145                                mdname(mddev));
5146                 else {
5147                         printk(KERN_ERR
5148                                "md/raid:%s: cannot start dirty degraded array.\n",
5149                                mdname(mddev));
5150                         goto abort;
5151                 }
5152         }
5153 
5154         if (mddev->degraded == 0)
5155                 printk(KERN_INFO "md/raid:%s: raid level %d active with %d out of %d"
5156                        " devices, algorithm %d\n", mdname(mddev), conf->level,
5157                        mddev->raid_disks-mddev->degraded, mddev->raid_disks,
5158                        mddev->new_layout);
5159         else
5160                 printk(KERN_ALERT "md/raid:%s: raid level %d active with %d"
5161                        " out of %d devices, algorithm %d\n",
5162                        mdname(mddev), conf->level,
5163                        mddev->raid_disks - mddev->degraded,
5164                        mddev->raid_disks, mddev->new_layout);
5165 
5166         print_raid5_conf(conf);
5167 
5168         if (conf->reshape_progress != MaxSector) {
5169                 conf->reshape_safe = conf->reshape_progress;
5170                 atomic_set(&conf->reshape_stripes, 0);
5171                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
5172                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
5173                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
5174                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
5175                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
5176                                                         "reshape");
5177         }
5178 
5179 
5180         /* Ok, everything is just fine now */
5181         if (mddev->to_remove == &raid5_attrs_group)
5182                 mddev->to_remove = NULL;
5183         else if (mddev->kobj.sd &&
5184             sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
5185                 printk(KERN_WARNING
5186                        "raid5: failed to create sysfs attributes for %s\n",
5187                        mdname(mddev));
5188         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
5189 
5190         plugger_init(&conf->plug, raid5_unplug);
5191         mddev->plug = &conf->plug;
5192         if (mddev->queue) {
5193                 int chunk_size;
5194                 /* read-ahead size must cover two whole stripes, which
5195                  * is 2 * (datadisks) * chunksize where 'n' is the
5196                  * number of raid devices
5197                  */
5198                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
5199                 int stripe = data_disks *
5200                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
5201                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
5202                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
5203 
5204                 blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
5205 
5206                 mddev->queue->backing_dev_info.congested_data = mddev;
5207                 mddev->queue->backing_dev_info.congested_fn = raid5_congested;
5208                 mddev->queue->queue_lock = &conf->device_lock;
5209                 mddev->queue->unplug_fn = raid5_unplug_queue;
5210 
5211                 chunk_size = mddev->chunk_sectors << 9;
5212                 blk_queue_io_min(mddev->queue, chunk_size);
5213                 blk_queue_io_opt(mddev->queue, chunk_size *
5214                                  (conf->raid_disks - conf->max_degraded));
5215 
5216                 list_for_each_entry(rdev, &mddev->disks, same_set)
5217                         disk_stack_limits(mddev->gendisk, rdev->bdev,
5218                                           rdev->data_offset << 9);
5219         }
5220 
5221         return 0;
5222 abort:
5223         md_unregister_thread(mddev->thread);
5224         mddev->thread = NULL;
5225         if (conf) {
5226                 print_raid5_conf(conf);
5227                 free_conf(conf);
5228         }
5229         mddev->private = NULL;
5230         printk(KERN_ALERT "md/raid:%s: failed to run raid set.\n", mdname(mddev));
5231         return -EIO;
5232 }
5233 
5234 static int stop(mddev_t *mddev)
5235 {
5236         raid5_conf_t *conf = mddev->private;
5237 
5238         md_unregister_thread(mddev->thread);
5239         mddev->thread = NULL;
5240         if (mddev->queue)
5241                 mddev->queue->backing_dev_info.congested_fn = NULL;
5242         plugger_flush(&conf->plug); /* the unplug fn references 'conf'*/
5243         free_conf(conf);
5244         mddev->private = NULL;
5245         mddev->to_remove = &raid5_attrs_group;
5246         return 0;
5247 }
5248 
5249 #ifdef DEBUG
5250 static void print_sh(struct seq_file *seq, struct stripe_head *sh)
5251 {
5252         int i;
5253 
5254         seq_printf(seq, "sh %llu, pd_idx %d, state %ld.\n",
5255                    (unsigned long long)sh->sector, sh->pd_idx, sh->state);
5256         seq_printf(seq, "sh %llu,  count %d.\n",
5257                    (unsigned long long)sh->sector, atomic_read(&sh->count));
5258         seq_printf(seq, "sh %llu, ", (unsigned long long)sh->sector);
5259         for (i = 0; i < sh->disks; i++) {
5260                 seq_printf(seq, "(cache%d: %p %ld) ",
5261                            i, sh->dev[i].page, sh->dev[i].flags);
5262         }
5263         seq_printf(seq, "\n");
5264 }
5265 
5266 static void printall(struct seq_file *seq, raid5_conf_t *conf)
5267 {
5268         struct stripe_head *sh;
5269         struct hlist_node *hn;
5270         int i;
5271 
5272         spin_lock_irq(&conf->device_lock);
5273         for (i = 0; i < NR_HASH; i++) {
5274                 hlist_for_each_entry(sh, hn, &conf->stripe_hashtbl[i], hash) {
5275                         if (sh->raid_conf != conf)
5276                                 continue;
5277                         print_sh(seq, sh);
5278                 }
5279         }
5280         spin_unlock_irq(&conf->device_lock);
5281 }
5282 #endif
5283 
5284 static void status(struct seq_file *seq, mddev_t *mddev)
5285 {
5286         raid5_conf_t *conf = mddev->private;
5287         int i;
5288 
5289         seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
5290                 mddev->chunk_sectors / 2, mddev->layout);
5291         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
5292         for (i = 0; i < conf->raid_disks; i++)
5293                 seq_printf (seq, "%s",
5294                                conf->disks[i].rdev &&
5295                                test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
5296         seq_printf (seq, "]");
5297 #ifdef DEBUG
5298         seq_printf (seq, "\n");
5299         printall(seq, conf);
5300 #endif
5301 }
5302 
5303 static void print_raid5_conf (raid5_conf_t *conf)
5304 {
5305         int i;
5306         struct disk_info *tmp;
5307 
5308         printk(KERN_DEBUG "RAID conf printout:\n");
5309         if (!conf) {
5310                 printk("(conf==NULL)\n");
5311                 return;
5312         }
5313         printk(KERN_DEBUG " --- level:%d rd:%d wd:%d\n", conf->level,
5314                conf->raid_disks,
5315                conf->raid_disks - conf->mddev->degraded);
5316 
5317         for (i = 0; i < conf->raid_disks; i++) {
5318                 char b[BDEVNAME_SIZE];
5319                 tmp = conf->disks + i;
5320                 if (tmp->rdev)
5321                         printk(KERN_DEBUG " disk %d, o:%d, dev:%s\n",
5322                                i, !test_bit(Faulty, &tmp->rdev->flags),
5323                                bdevname(tmp->rdev->bdev, b));
5324         }
5325 }
5326 
5327 static int raid5_spare_active(mddev_t *mddev)
5328 {
5329         int i;
5330         raid5_conf_t *conf = mddev->private;
5331         struct disk_info *tmp;
5332         int count = 0;
5333         unsigned long flags;
5334 
5335         for (i = 0; i < conf->raid_disks; i++) {
5336                 tmp = conf->disks + i;
5337                 if (tmp->rdev
5338                     && tmp->rdev->recovery_offset == MaxSector
5339                     && !test_bit(Faulty, &tmp->rdev->flags)
5340                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
5341                         count++;
5342                         sysfs_notify_dirent(tmp->rdev->sysfs_state);
5343                 }
5344         }
5345         spin_lock_irqsave(&conf->device_lock, flags);
5346         mddev->degraded -= count;
5347         spin_unlock_irqrestore(&conf->device_lock, flags);
5348         print_raid5_conf(conf);
5349         return count;
5350 }
5351 
5352 static int raid5_remove_disk(mddev_t *mddev, int number)
5353 {
5354         raid5_conf_t *conf = mddev->private;
5355         int err = 0;
5356         mdk_rdev_t *rdev;
5357         struct disk_info *p = conf->disks + number;
5358 
5359         print_raid5_conf(conf);
5360         rdev = p->rdev;
5361         if (rdev) {
5362                 if (number >= conf->raid_disks &&
5363                     conf->reshape_progress == MaxSector)
5364                         clear_bit(In_sync, &rdev->flags);
5365 
5366                 if (test_bit(In_sync, &rdev->flags) ||
5367                     atomic_read(&rdev->nr_pending)) {
5368                         err = -EBUSY;
5369                         goto abort;
5370                 }
5371                 /* Only remove non-faulty devices if recovery
5372                  * isn't possible.
5373                  */
5374                 if (!test_bit(Faulty, &rdev->flags) &&
5375                     !has_failed(conf) &&
5376                     number < conf->raid_disks) {
5377                         err = -EBUSY;
5378                         goto abort;
5379                 }
5380                 p->rdev = NULL;
5381                 synchronize_rcu();
5382                 if (atomic_read(&rdev->nr_pending)) {
5383                         /* lost the race, try later */
5384                         err = -EBUSY;
5385                         p->rdev = rdev;
5386                 }
5387         }
5388 abort:
5389 
5390         print_raid5_conf(conf);
5391         return err;
5392 }
5393 
5394 static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
5395 {
5396         raid5_conf_t *conf = mddev->private;
5397         int err = -EEXIST;
5398         int disk;
5399         struct disk_info *p;
5400         int first = 0;
5401         int last = conf->raid_disks - 1;
5402 
5403         if (has_failed(conf))
5404                 /* no point adding a device */
5405                 return -EINVAL;
5406 
5407         if (rdev->raid_disk >= 0)
5408                 first = last = rdev->raid_disk;
5409 
5410         /*
5411          * find the disk ... but prefer rdev->saved_raid_disk
5412          * if possible.
5413          */
5414         if (rdev->saved_raid_disk >= 0 &&
5415             rdev->saved_raid_disk >= first &&
5416             conf->disks[rdev->saved_raid_disk].rdev == NULL)
5417                 disk = rdev->saved_raid_disk;
5418         else
5419                 disk = first;
5420         for ( ; disk <= last ; disk++)
5421                 if ((p=conf->disks + disk)->rdev == NULL) {
5422                         clear_bit(In_sync, &rdev->flags);
5423                         rdev->raid_disk = disk;
5424                         err = 0;
5425                         if (rdev->saved_raid_disk != disk)
5426                                 conf->fullsync = 1;
5427                         rcu_assign_pointer(p->rdev, rdev);
5428                         break;
5429                 }
5430         print_raid5_conf(conf);
5431         return err;
5432 }
5433 
5434 static int raid5_resize(mddev_t *mddev, sector_t sectors)
5435 {
5436         /* no resync is happening, and there is enough space
5437          * on all devices, so we can resize.
5438          * We need to make sure resync covers any new space.
5439          * If the array is shrinking we should possibly wait until
5440          * any io in the removed space completes, but it hardly seems
5441          * worth it.
5442          */
5443         sectors &= ~((sector_t)mddev->chunk_sectors - 1);
5444         md_set_array_sectors(mddev, raid5_size(mddev, sectors,
5445                                                mddev->raid_disks));
5446         if (mddev->array_sectors >
5447             raid5_size(mddev, sectors, mddev->raid_disks))
5448                 return -EINVAL;
5449         set_capacity(mddev->gendisk, mddev->array_sectors);
5450         revalidate_disk(mddev->gendisk);
5451         if (sectors > mddev->dev_sectors && mddev->recovery_cp == MaxSector) {
5452                 mddev->recovery_cp = mddev->dev_sectors;
5453                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
5454         }
5455         mddev->dev_sectors = sectors;
5456         mddev->resync_max_sectors = sectors;
5457         return 0;
5458 }
5459 
5460 static int check_stripe_cache(mddev_t *mddev)
5461 {
5462         /* Can only proceed if there are plenty of stripe_heads.
5463          * We need a minimum of one full stripe,, and for sensible progress
5464          * it is best to have about 4 times that.
5465          * If we require 4 times, then the default 256 4K stripe_heads will
5466          * allow for chunk sizes up to 256K, which is probably OK.
5467          * If the chunk size is greater, user-space should request more
5468          * stripe_heads first.
5469          */
5470         raid5_conf_t *conf = mddev->private;
5471         if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
5472             > conf->max_nr_stripes ||
5473             ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
5474             > conf->max_nr_stripes) {
5475                 printk(KERN_WARNING "md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
5476                        mdname(mddev),
5477                        ((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
5478                         / STRIPE_SIZE)*4);
5479                 return 0;
5480         }
5481         return 1;
5482 }
5483 
5484 static int check_reshape(mddev_t *mddev)
5485 {
5486         raid5_conf_t *conf = mddev->private;
5487 
5488         if (mddev->delta_disks == 0 &&
5489             mddev->new_layout == mddev->layout &&
5490             mddev->new_chunk_sectors == mddev->chunk_sectors)
5491                 return 0; /* nothing to do */
5492         if (mddev->bitmap)
5493                 /* Cannot grow a bitmap yet */
5494                 return -EBUSY;
5495         if (has_failed(conf))
5496                 return -EINVAL;
5497         if (mddev->delta_disks < 0) {
5498                 /* We might be able to shrink, but the devices must
5499                  * be made bigger first.
5500                  * For raid6, 4 is the minimum size.
5501                  * Otherwise 2 is the minimum
5502                  */
5503                 int min = 2;
5504                 if (mddev->level == 6)
5505                         min = 4;
5506                 if (mddev->raid_disks + mddev->delta_disks < min)
5507                         return -EINVAL;
5508         }
5509 
5510         if (!check_stripe_cache(mddev))
5511                 return -ENOSPC;
5512 
5513         return resize_stripes(conf, conf->raid_disks + mddev->delta_disks);
5514 }
5515 
5516 static int raid5_start_reshape(mddev_t *mddev)
5517 {
5518         raid5_conf_t *conf = mddev->private;
5519         mdk_rdev_t *rdev;
5520         int spares = 0;
5521         int added_devices = 0;
5522         unsigned long flags;
5523 
5524         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
5525                 return -EBUSY;
5526 
5527         if (!check_stripe_cache(mddev))
5528                 return -ENOSPC;
5529 
5530         list_for_each_entry(rdev, &mddev->disks, same_set)
5531                 if (rdev->raid_disk < 0 &&
5532                     !test_bit(Faulty, &rdev->flags))
5533                         spares++;
5534 
5535         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
5536                 /* Not enough devices even to make a degraded array
5537                  * of that size
5538                  */
5539                 return -EINVAL;
5540 
5541         /* Refuse to reduce size of the array.  Any reductions in
5542          * array size must be through explicit setting of array_size
5543          * attribute.
5544          */
5545         if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
5546             < mddev->array_sectors) {
5547                 printk(KERN_ERR "md/raid:%s: array size must be reduced "
5548                        "before number of disks\n", mdname(mddev));
5549                 return -EINVAL;
5550         }
5551 
5552         atomic_set(&conf->reshape_stripes, 0);
5553         spin_lock_irq(&conf->device_lock);
5554         conf->previous_raid_disks = conf->raid_disks;
5555         conf->raid_disks += mddev->delta_disks;
5556         conf->prev_chunk_sectors = conf->chunk_sectors;
5557         conf->chunk_sectors = mddev->new_chunk_sectors;
5558         conf->prev_algo = conf->algorithm;
5559         conf->algorithm = mddev->new_layout;
5560         if (mddev->delta_disks < 0)
5561                 conf->reshape_progress = raid5_size(mddev, 0, 0);
5562         else
5563                 conf->reshape_progress = 0;
5564         conf->reshape_safe = conf->reshape_progress;
5565         conf->generation++;
5566         spin_unlock_irq(&conf->device_lock);
5567 
5568         /* Add some new drives, as many as will fit.
5569          * We know there are enough to make the newly sized array work.
5570          * Don't add devices if we are reducing the number of
5571          * devices in the array.  This is because it is not possible
5572          * to correctly record the "partially reconstructed" state of
5573          * such devices during the reshape and confusion could result.
5574          */
5575         if (mddev->delta_disks >= 0)
5576             list_for_each_entry(rdev, &mddev->disks, same_set)
5577                 if (rdev->raid_disk < 0 &&
5578                     !test_bit(Faulty, &rdev->flags)) {
5579                         if (raid5_add_disk(mddev, rdev) == 0) {
5580                                 char nm[20];
5581                                 if (rdev->raid_disk >= conf->previous_raid_disks) {
5582                                         set_bit(In_sync, &rdev->flags);
5583                                         added_devices++;
5584                                 } else
5585                                         rdev->recovery_offset = 0;
5586                                 sprintf(nm, "rd%d", rdev->raid_disk);
5587                                 if (sysfs_create_link(&mddev->kobj,
5588                                                       &rdev->kobj, nm))
5589                                         /* Failure here is OK */;
5590                         } else
5591                                 break;
5592                 }
5593 
5594         /* When a reshape changes the number of devices, ->degraded
5595          * is measured against the larger of the pre and post number of
5596          * devices.*/
5597         if (mddev->delta_disks > 0) {
5598                 spin_lock_irqsave(&conf->device_lock, flags);
5599                 mddev->degraded += (conf->raid_disks - conf->previous_raid_disks)
5600                         - added_devices;
5601                 spin_unlock_irqrestore(&conf->device_lock, flags);
5602         }
5603         mddev->raid_disks = conf->raid_disks;
5604         mddev->reshape_position = conf->reshape_progress;
5605         set_bit(MD_CHANGE_DEVS, &mddev->flags);
5606 
5607         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
5608         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
5609         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
5610         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
5611         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
5612                                                 "reshape");
5613         if (!mddev->sync_thread) {
5614                 mddev->recovery = 0;
5615                 spin_lock_irq(&conf->device_lock);
5616                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
5617                 conf->reshape_progress = MaxSector;
5618                 spin_unlock_irq(&conf->device_lock);
5619                 return -EAGAIN;
5620         }
5621         conf->reshape_checkpoint = jiffies;
5622         md_wakeup_thread(mddev->sync_thread);
5623         md_new_event(mddev);
5624         return 0;
5625 }
5626 
5627 /* This is called from the reshape thread and should make any
5628  * changes needed in 'conf'
5629  */
5630 static void end_reshape(raid5_conf_t *conf)
5631 {
5632 
5633         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
5634 
5635                 spin_lock_irq(&conf->device_lock);
5636                 conf->previous_raid_disks = conf->raid_disks;
5637                 conf->reshape_progress = MaxSector;
5638                 spin_unlock_irq(&conf->device_lock);
5639                 wake_up(&conf->wait_for_overlap);
5640 
5641                 /* read-ahead size must cover two whole stripes, which is
5642                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
5643                  */
5644                 if (conf->mddev->queue) {
5645                         int data_disks = conf->raid_disks - conf->max_degraded;
5646                         int stripe = data_disks * ((conf->chunk_sectors << 9)
5647                                                    / PAGE_SIZE);
5648                         if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
5649                                 conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
5650                 }
5651         }
5652 }
5653 
5654 /* This is called from the raid5d thread with mddev_lock held.
5655  * It makes config changes to the device.
5656  */
5657 static void raid5_finish_reshape(mddev_t *mddev)
5658 {
5659         raid5_conf_t *conf = mddev->private;
5660 
5661         if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
5662 
5663                 if (mddev->delta_disks > 0) {
5664                         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
5665                         set_capacity(mddev->gendisk, mddev->array_sectors);
5666                         revalidate_disk(mddev->gendisk);
5667                 } else {
5668                         int d;
5669                         mddev->degraded = conf->raid_disks;
5670                         for (d = 0; d < conf->raid_disks ; d++)
5671                                 if (conf->disks[d].rdev &&
5672                                     test_bit(In_sync,
5673                                              &conf->disks[d].rdev->flags))
5674                                         mddev->degraded--;
5675                         for (d = conf->raid_disks ;
5676                              d < conf->raid_disks - mddev->delta_disks;
5677                              d++) {
5678                                 mdk_rdev_t *rdev = conf->disks[d].rdev;
5679                                 if (rdev && raid5_remove_disk(mddev, d) == 0) {
5680                                         char nm[20];
5681                                         sprintf(nm, "rd%d", rdev->raid_disk);
5682                                         sysfs_remove_link(&mddev->kobj, nm);
5683                                         rdev->raid_disk = -1;
5684                                 }
5685                         }
5686                 }
5687                 mddev->layout = conf->algorithm;
5688                 mddev->chunk_sectors = conf->chunk_sectors;
5689                 mddev->reshape_position = MaxSector;
5690                 mddev->delta_disks = 0;
5691         }
5692 }
5693 
5694 static void raid5_quiesce(mddev_t *mddev, int state)
5695 {
5696         raid5_conf_t *conf = mddev->private;
5697 
5698         switch(state) {
5699         case 2: /* resume for a suspend */
5700                 wake_up(&conf->wait_for_overlap);
5701                 break;
5702 
5703         case 1: /* stop all writes */
5704                 spin_lock_irq(&conf->device_lock);
5705                 /* '2' tells resync/reshape to pause so that all
5706                  * active stripes can drain
5707                  */
5708                 conf->quiesce = 2;
5709                 wait_event_lock_irq(conf->wait_for_stripe,
5710                                     atomic_read(&conf->active_stripes) == 0 &&
5711                                     atomic_read(&conf->active_aligned_reads) == 0,
5712                                     conf->device_lock, /* nothing */);
5713                 conf->quiesce = 1;
5714                 spin_unlock_irq(&conf->device_lock);
5715                 /* allow reshape to continue */
5716                 wake_up(&conf->wait_for_overlap);
5717                 break;
5718 
5719         case 0: /* re-enable writes */
5720                 spin_lock_irq(&conf->device_lock);
5721                 conf->quiesce = 0;
5722                 wake_up(&conf->wait_for_stripe);
5723                 wake_up(&conf->wait_for_overlap);
5724                 spin_unlock_irq(&conf->device_lock);
5725                 break;
5726         }
5727 }
5728 
5729 
5730 static void *raid45_takeover_raid0(mddev_t *mddev, int level)
5731 {
5732         struct raid0_private_data *raid0_priv = mddev->private;
5733 
5734         /* for raid0 takeover only one zone is supported */
5735         if (raid0_priv->nr_strip_zones > 1) {
5736                 printk(KERN_ERR "md/raid:%s: cannot takeover raid0 with more than one zone.\n",
5737                        mdname(mddev));
5738                 return ERR_PTR(-EINVAL);
5739         }
5740 
5741         mddev->new_level = level;
5742         mddev->new_layout = ALGORITHM_PARITY_N;
5743         mddev->new_chunk_sectors = mddev->chunk_sectors;
5744         mddev->raid_disks += 1;
5745         mddev->delta_disks = 1;
5746         /* make sure it will be not marked as dirty */
5747         mddev->recovery_cp = MaxSector;
5748 
5749         return setup_conf(mddev);
5750 }
5751 
5752 
5753 static void *raid5_takeover_raid1(mddev_t *mddev)
5754 {
5755         int chunksect;
5756 
5757         if (mddev->raid_disks != 2 ||
5758             mddev->degraded > 1)
5759                 return ERR_PTR(-EINVAL);
5760 
5761         /* Should check if there are write-behind devices? */
5762 
5763         chunksect = 64*2; /* 64K by default */
5764 
5765         /* The array must be an exact multiple of chunksize */
5766         while (chunksect && (mddev->array_sectors & (chunksect-1)))
5767                 chunksect >>= 1;
5768 
5769         if ((chunksect<<9) < STRIPE_SIZE)
5770                 /* array size does not allow a suitable chunk size */
5771                 return ERR_PTR(-EINVAL);
5772 
5773         mddev->new_level = 5;
5774         mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
5775         mddev->new_chunk_sectors = chunksect;
5776 
5777         return setup_conf(mddev);
5778 }
5779 
5780 static void *raid5_takeover_raid6(mddev_t *mddev)
5781 {
5782         int new_layout;
5783 
5784         switch (mddev->layout) {
5785         case ALGORITHM_LEFT_ASYMMETRIC_6:
5786                 new_layout = ALGORITHM_LEFT_ASYMMETRIC;
5787                 break;
5788         case ALGORITHM_RIGHT_ASYMMETRIC_6:
5789                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
5790                 break;
5791         case ALGORITHM_LEFT_SYMMETRIC_6:
5792                 new_layout = ALGORITHM_LEFT_SYMMETRIC;
5793                 break;
5794         case ALGORITHM_RIGHT_SYMMETRIC_6:
5795                 new_layout = ALGORITHM_RIGHT_SYMMETRIC;
5796                 break;
5797         case ALGORITHM_PARITY_0_6:
5798                 new_layout = ALGORITHM_PARITY_0;
5799                 break;
5800         case ALGORITHM_PARITY_N:
5801                 new_layout = ALGORITHM_PARITY_N;
5802                 break;
5803         default:
5804                 return ERR_PTR(-EINVAL);
5805         }
5806         mddev->new_level = 5;
5807         mddev->new_layout = new_layout;
5808         mddev->delta_disks = -1;
5809         mddev->raid_disks -= 1;
5810         return setup_conf(mddev);
5811 }
5812 
5813 
5814 static int raid5_check_reshape(mddev_t *mddev)
5815 {
5816         /* For a 2-drive array, the layout and chunk size can be changed
5817          * immediately as not restriping is needed.
5818          * For larger arrays we record the new value - after validation
5819          * to be used by a reshape pass.
5820          */
5821         raid5_conf_t *conf = mddev->private;
5822         int new_chunk = mddev->new_chunk_sectors;
5823 
5824         if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
5825                 return -EINVAL;
5826         if (new_chunk > 0) {
5827                 if (!is_power_of_2(new_chunk))
5828                         return -EINVAL;
5829                 if (new_chunk < (PAGE_SIZE>>9))
5830                         return -EINVAL;
5831                 if (mddev->array_sectors & (new_chunk-1))
5832                         /* not factor of array size */
5833                         return -EINVAL;
5834         }
5835 
5836         /* They look valid */
5837 
5838         if (mddev->raid_disks == 2) {
5839                 /* can make the change immediately */
5840                 if (mddev->new_layout >= 0) {
5841                         conf->algorithm = mddev->new_layout;
5842                         mddev->layout = mddev->new_layout;
5843                 }
5844                 if (new_chunk > 0) {
5845                         conf->chunk_sectors = new_chunk ;
5846                         mddev->chunk_sectors = new_chunk;
5847                 }
5848                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
5849                 md_wakeup_thread(mddev->thread);
5850         }
5851         return check_reshape(mddev);
5852 }
5853 
5854 static int raid6_check_reshape(mddev_t *mddev)
5855 {
5856         int new_chunk = mddev->new_chunk_sectors;
5857 
5858         if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
5859                 return -EINVAL;
5860         if (new_chunk > 0) {
5861                 if (!is_power_of_2(new_chunk))
5862                         return -EINVAL;
5863                 if (new_chunk < (PAGE_SIZE >> 9))
5864                         return -EINVAL;
5865                 if (mddev->array_sectors & (new_chunk-1))
5866                         /* not factor of array size */
5867                         return -EINVAL;
5868         }
5869 
5870         /* They look valid */
5871         return check_reshape(mddev);
5872 }
5873 
5874 static void *raid5_takeover(mddev_t *mddev)
5875 {
5876         /* raid5 can take over:
5877          *  raid0 - if there is only one strip zone - make it a raid4 layout
5878          *  raid1 - if there are two drives.  We need to know the chunk size
5879          *  raid4 - trivial - just use a raid4 layout.
5880          *  raid6 - Providing it is a *_6 layout
5881          */
5882         if (mddev->level == 0)
5883                 return raid45_takeover_raid0(mddev, 5);
5884         if (mddev->level == 1)
5885                 return raid5_takeover_raid1(mddev);
5886         if (mddev->level == 4) {
5887                 mddev->new_layout = ALGORITHM_PARITY_N;
5888                 mddev->new_level = 5;
5889                 return setup_conf(mddev);
5890         }
5891         if (mddev->level == 6)
5892                 return raid5_takeover_raid6(mddev);
5893 
5894         return ERR_PTR(-EINVAL);
5895 }
5896 
5897 static void *raid4_takeover(mddev_t *mddev)
5898 {
5899         /* raid4 can take over:
5900          *  raid0 - if there is only one strip zone
5901          *  raid5 - if layout is right
5902          */
5903         if (mddev->level == 0)
5904                 return raid45_takeover_raid0(mddev, 4);
5905         if (mddev->level == 5 &&
5906             mddev->layout == ALGORITHM_PARITY_N) {
5907                 mddev->new_layout = 0;
5908                 mddev->new_level = 4;
5909                 return setup_conf(mddev);
5910         }
5911         return ERR_PTR(-EINVAL);
5912 }
5913 
5914 static struct mdk_personality raid5_personality;
5915 
5916 static void *raid6_takeover(mddev_t *mddev)
5917 {
5918         /* Currently can only take over a raid5.  We map the
5919          * personality to an equivalent raid6 personality
5920          * with the Q block at the end.
5921          */
5922         int new_layout;
5923 
5924         if (mddev->pers != &raid5_personality)
5925                 return ERR_PTR(-EINVAL);
5926         if (mddev->degraded > 1)
5927                 return ERR_PTR(-EINVAL);
5928         if (mddev->raid_disks > 253)
5929                 return ERR_PTR(-EINVAL);
5930         if (mddev->raid_disks < 3)
5931                 return ERR_PTR(-EINVAL);
5932 
5933         switch (mddev->layout) {
5934         case ALGORITHM_LEFT_ASYMMETRIC:
5935                 new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
5936                 break;
5937         case ALGORITHM_RIGHT_ASYMMETRIC:
5938                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
5939                 break;
5940         case ALGORITHM_LEFT_SYMMETRIC:
5941                 new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
5942                 break;
5943         case ALGORITHM_RIGHT_SYMMETRIC:
5944                 new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
5945                 break;
5946         case ALGORITHM_PARITY_0:
5947                 new_layout = ALGORITHM_PARITY_0_6;
5948                 break;
5949         case ALGORITHM_PARITY_N:
5950                 new_layout = ALGORITHM_PARITY_N;
5951                 break;
5952         default:
5953                 return ERR_PTR(-EINVAL);
5954         }
5955         mddev->new_level = 6;
5956         mddev->new_layout = new_layout;
5957         mddev->delta_disks = 1;
5958         mddev->raid_disks += 1;
5959         return setup_conf(mddev);
5960 }
5961 
5962 
5963 static struct mdk_personality raid6_personality =
5964 {
5965         .name           = "raid6",
5966         .level          = 6,
5967         .owner          = THIS_MODULE,
5968         .make_request   = make_request,
5969         .run            = run,
5970         .stop           = stop,
5971         .status         = status,
5972         .error_handler  = error,
5973         .hot_add_disk   = raid5_add_disk,
5974         .hot_remove_disk= raid5_remove_disk,
5975         .spare_active   = raid5_spare_active,
5976         .sync_request   = sync_request,
5977         .resize         = raid5_resize,
5978         .size           = raid5_size,
5979         .check_reshape  = raid6_check_reshape,
5980         .start_reshape  = raid5_start_reshape,
5981         .finish_reshape = raid5_finish_reshape,
5982         .quiesce        = raid5_quiesce,
5983         .takeover       = raid6_takeover,
5984 };
5985 static struct mdk_personality raid5_personality =
5986 {
5987         .name           = "raid5",
5988         .level          = 5,
5989         .owner          = THIS_MODULE,
5990         .make_request   = make_request,
5991         .run            = run,
5992         .stop           = stop,
5993         .status         = status,
5994         .error_handler  = error,
5995         .hot_add_disk   = raid5_add_disk,
5996         .hot_remove_disk= raid5_remove_disk,
5997         .spare_active   = raid5_spare_active,
5998         .sync_request   = sync_request,
5999         .resize         = raid5_resize,
6000         .size           = raid5_size,
6001         .check_reshape  = raid5_check_reshape,
6002         .start_reshape  = raid5_start_reshape,
6003         .finish_reshape = raid5_finish_reshape,
6004         .quiesce        = raid5_quiesce,
6005         .takeover       = raid5_takeover,
6006 };
6007 
6008 static struct mdk_personality raid4_personality =
6009 {
6010         .name           = "raid4",
6011         .level          = 4,
6012         .owner          = THIS_MODULE,
6013         .make_request   = make_request,
6014         .run            = run,
6015         .stop           = stop,
6016         .status         = status,
6017         .error_handler  = error,
6018         .hot_add_disk   = raid5_add_disk,
6019         .hot_remove_disk= raid5_remove_disk,
6020         .spare_active   = raid5_spare_active,
6021         .sync_request   = sync_request,
6022         .resize         = raid5_resize,
6023         .size           = raid5_size,
6024         .check_reshape  = raid5_check_reshape,
6025         .start_reshape  = raid5_start_reshape,
6026         .finish_reshape = raid5_finish_reshape,
6027         .quiesce        = raid5_quiesce,
6028         .takeover       = raid4_takeover,
6029 };
6030 
6031 static int __init raid5_init(void)
6032 {
6033         register_md_personality(&raid6_personality);
6034         register_md_personality(&raid5_personality);
6035         register_md_personality(&raid4_personality);
6036         return 0;
6037 }
6038 
6039 static void raid5_exit(void)
6040 {
6041         unregister_md_personality(&raid6_personality);
6042         unregister_md_personality(&raid5_personality);
6043         unregister_md_personality(&raid4_personality);
6044 }
6045 
6046 module_init(raid5_init);
6047 module_exit(raid5_exit);
6048 MODULE_LICENSE("GPL");
6049 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
6050 MODULE_ALIAS("md-personality-4"); /* RAID5 */
6051 MODULE_ALIAS("md-raid5");
6052 MODULE_ALIAS("md-raid4");
6053 MODULE_ALIAS("md-level-5");
6054 MODULE_ALIAS("md-level-4");
6055 MODULE_ALIAS("md-personality-8"); /* RAID6 */
6056 MODULE_ALIAS("md-raid6");
6057 MODULE_ALIAS("md-level-6");
6058 
6059 /* This used to be two separate modules, they were: */
6060 MODULE_ALIAS("raid5");
6061 MODULE_ALIAS("raid6");
6062 

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