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Linux/block/bio-integrity.c

  1 /*
  2  * bio-integrity.c - bio data integrity extensions
  3  *
  4  * Copyright (C) 2007, 2008, 2009 Oracle Corporation
  5  * Written by: Martin K. Petersen <martin.petersen@oracle.com>
  6  *
  7  * This program is free software; you can redistribute it and/or
  8  * modify it under the terms of the GNU General Public License version
  9  * 2 as published by the Free Software Foundation.
 10  *
 11  * This program is distributed in the hope that it will be useful, but
 12  * WITHOUT ANY WARRANTY; without even the implied warranty of
 13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 14  * General Public License for more details.
 15  *
 16  * You should have received a copy of the GNU General Public License
 17  * along with this program; see the file COPYING.  If not, write to
 18  * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
 19  * USA.
 20  *
 21  */
 22 
 23 #include <linux/blkdev.h>
 24 #include <linux/mempool.h>
 25 #include <linux/export.h>
 26 #include <linux/bio.h>
 27 #include <linux/workqueue.h>
 28 #include <linux/slab.h>
 29 #include "blk.h"
 30 
 31 #define BIP_INLINE_VECS 4
 32 
 33 static struct kmem_cache *bip_slab;
 34 static struct workqueue_struct *kintegrityd_wq;
 35 
 36 void blk_flush_integrity(void)
 37 {
 38         flush_workqueue(kintegrityd_wq);
 39 }
 40 
 41 /**
 42  * bio_integrity_alloc - Allocate integrity payload and attach it to bio
 43  * @bio:        bio to attach integrity metadata to
 44  * @gfp_mask:   Memory allocation mask
 45  * @nr_vecs:    Number of integrity metadata scatter-gather elements
 46  *
 47  * Description: This function prepares a bio for attaching integrity
 48  * metadata.  nr_vecs specifies the maximum number of pages containing
 49  * integrity metadata that can be attached.
 50  */
 51 struct bio_integrity_payload *bio_integrity_alloc(struct bio *bio,
 52                                                   gfp_t gfp_mask,
 53                                                   unsigned int nr_vecs)
 54 {
 55         struct bio_integrity_payload *bip;
 56         struct bio_set *bs = bio->bi_pool;
 57         unsigned inline_vecs;
 58 
 59         if (!bs || !bs->bio_integrity_pool) {
 60                 bip = kmalloc(sizeof(struct bio_integrity_payload) +
 61                               sizeof(struct bio_vec) * nr_vecs, gfp_mask);
 62                 inline_vecs = nr_vecs;
 63         } else {
 64                 bip = mempool_alloc(bs->bio_integrity_pool, gfp_mask);
 65                 inline_vecs = BIP_INLINE_VECS;
 66         }
 67 
 68         if (unlikely(!bip))
 69                 return ERR_PTR(-ENOMEM);
 70 
 71         memset(bip, 0, sizeof(*bip));
 72 
 73         if (nr_vecs > inline_vecs) {
 74                 unsigned long idx = 0;
 75 
 76                 bip->bip_vec = bvec_alloc(gfp_mask, nr_vecs, &idx,
 77                                           bs->bvec_integrity_pool);
 78                 if (!bip->bip_vec)
 79                         goto err;
 80                 bip->bip_max_vcnt = bvec_nr_vecs(idx);
 81                 bip->bip_slab = idx;
 82         } else {
 83                 bip->bip_vec = bip->bip_inline_vecs;
 84                 bip->bip_max_vcnt = inline_vecs;
 85         }
 86 
 87         bip->bip_bio = bio;
 88         bio->bi_integrity = bip;
 89         bio->bi_opf |= REQ_INTEGRITY;
 90 
 91         return bip;
 92 err:
 93         mempool_free(bip, bs->bio_integrity_pool);
 94         return ERR_PTR(-ENOMEM);
 95 }
 96 EXPORT_SYMBOL(bio_integrity_alloc);
 97 
 98 /**
 99  * bio_integrity_free - Free bio integrity payload
100  * @bio:        bio containing bip to be freed
101  *
102  * Description: Used to free the integrity portion of a bio. Usually
103  * called from bio_free().
104  */
105 void bio_integrity_free(struct bio *bio)
106 {
107         struct bio_integrity_payload *bip = bio_integrity(bio);
108         struct bio_set *bs = bio->bi_pool;
109 
110         if (bip->bip_flags & BIP_BLOCK_INTEGRITY)
111                 kfree(page_address(bip->bip_vec->bv_page) +
112                       bip->bip_vec->bv_offset);
113 
114         if (bs && bs->bio_integrity_pool) {
115                 bvec_free(bs->bvec_integrity_pool, bip->bip_vec, bip->bip_slab);
116 
117                 mempool_free(bip, bs->bio_integrity_pool);
118         } else {
119                 kfree(bip);
120         }
121 
122         bio->bi_integrity = NULL;
123 }
124 EXPORT_SYMBOL(bio_integrity_free);
125 
126 /**
127  * bio_integrity_add_page - Attach integrity metadata
128  * @bio:        bio to update
129  * @page:       page containing integrity metadata
130  * @len:        number of bytes of integrity metadata in page
131  * @offset:     start offset within page
132  *
133  * Description: Attach a page containing integrity metadata to bio.
134  */
135 int bio_integrity_add_page(struct bio *bio, struct page *page,
136                            unsigned int len, unsigned int offset)
137 {
138         struct bio_integrity_payload *bip = bio_integrity(bio);
139         struct bio_vec *iv;
140 
141         if (bip->bip_vcnt >= bip->bip_max_vcnt) {
142                 printk(KERN_ERR "%s: bip_vec full\n", __func__);
143                 return 0;
144         }
145 
146         iv = bip->bip_vec + bip->bip_vcnt;
147 
148         if (bip->bip_vcnt &&
149             bvec_gap_to_prev(bdev_get_queue(bio->bi_bdev),
150                              &bip->bip_vec[bip->bip_vcnt - 1], offset))
151                 return 0;
152 
153         iv->bv_page = page;
154         iv->bv_len = len;
155         iv->bv_offset = offset;
156         bip->bip_vcnt++;
157 
158         return len;
159 }
160 EXPORT_SYMBOL(bio_integrity_add_page);
161 
162 /**
163  * bio_integrity_enabled - Check whether integrity can be passed
164  * @bio:        bio to check
165  *
166  * Description: Determines whether bio_integrity_prep() can be called
167  * on this bio or not.  bio data direction and target device must be
168  * set prior to calling.  The functions honors the write_generate and
169  * read_verify flags in sysfs.
170  */
171 bool bio_integrity_enabled(struct bio *bio)
172 {
173         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
174 
175         if (bio_op(bio) != REQ_OP_READ && bio_op(bio) != REQ_OP_WRITE)
176                 return false;
177 
178         /* Already protected? */
179         if (bio_integrity(bio))
180                 return false;
181 
182         if (bi == NULL)
183                 return false;
184 
185         if (bio_data_dir(bio) == READ && bi->profile->verify_fn != NULL &&
186             (bi->flags & BLK_INTEGRITY_VERIFY))
187                 return true;
188 
189         if (bio_data_dir(bio) == WRITE && bi->profile->generate_fn != NULL &&
190             (bi->flags & BLK_INTEGRITY_GENERATE))
191                 return true;
192 
193         return false;
194 }
195 EXPORT_SYMBOL(bio_integrity_enabled);
196 
197 /**
198  * bio_integrity_intervals - Return number of integrity intervals for a bio
199  * @bi:         blk_integrity profile for device
200  * @sectors:    Size of the bio in 512-byte sectors
201  *
202  * Description: The block layer calculates everything in 512 byte
203  * sectors but integrity metadata is done in terms of the data integrity
204  * interval size of the storage device.  Convert the block layer sectors
205  * to the appropriate number of integrity intervals.
206  */
207 static inline unsigned int bio_integrity_intervals(struct blk_integrity *bi,
208                                                    unsigned int sectors)
209 {
210         return sectors >> (bi->interval_exp - 9);
211 }
212 
213 static inline unsigned int bio_integrity_bytes(struct blk_integrity *bi,
214                                                unsigned int sectors)
215 {
216         return bio_integrity_intervals(bi, sectors) * bi->tuple_size;
217 }
218 
219 /**
220  * bio_integrity_process - Process integrity metadata for a bio
221  * @bio:        bio to generate/verify integrity metadata for
222  * @proc_fn:    Pointer to the relevant processing function
223  */
224 static int bio_integrity_process(struct bio *bio,
225                                  integrity_processing_fn *proc_fn)
226 {
227         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
228         struct blk_integrity_iter iter;
229         struct bvec_iter bviter;
230         struct bio_vec bv;
231         struct bio_integrity_payload *bip = bio_integrity(bio);
232         unsigned int ret = 0;
233         void *prot_buf = page_address(bip->bip_vec->bv_page) +
234                 bip->bip_vec->bv_offset;
235 
236         iter.disk_name = bio->bi_bdev->bd_disk->disk_name;
237         iter.interval = 1 << bi->interval_exp;
238         iter.seed = bip_get_seed(bip);
239         iter.prot_buf = prot_buf;
240 
241         bio_for_each_segment(bv, bio, bviter) {
242                 void *kaddr = kmap_atomic(bv.bv_page);
243 
244                 iter.data_buf = kaddr + bv.bv_offset;
245                 iter.data_size = bv.bv_len;
246 
247                 ret = proc_fn(&iter);
248                 if (ret) {
249                         kunmap_atomic(kaddr);
250                         return ret;
251                 }
252 
253                 kunmap_atomic(kaddr);
254         }
255         return ret;
256 }
257 
258 /**
259  * bio_integrity_prep - Prepare bio for integrity I/O
260  * @bio:        bio to prepare
261  *
262  * Description: Allocates a buffer for integrity metadata, maps the
263  * pages and attaches them to a bio.  The bio must have data
264  * direction, target device and start sector set priot to calling.  In
265  * the WRITE case, integrity metadata will be generated using the
266  * block device's integrity function.  In the READ case, the buffer
267  * will be prepared for DMA and a suitable end_io handler set up.
268  */
269 int bio_integrity_prep(struct bio *bio)
270 {
271         struct bio_integrity_payload *bip;
272         struct blk_integrity *bi;
273         struct request_queue *q;
274         void *buf;
275         unsigned long start, end;
276         unsigned int len, nr_pages;
277         unsigned int bytes, offset, i;
278         unsigned int intervals;
279 
280         bi = bdev_get_integrity(bio->bi_bdev);
281         q = bdev_get_queue(bio->bi_bdev);
282         BUG_ON(bi == NULL);
283         BUG_ON(bio_integrity(bio));
284 
285         intervals = bio_integrity_intervals(bi, bio_sectors(bio));
286 
287         /* Allocate kernel buffer for protection data */
288         len = intervals * bi->tuple_size;
289         buf = kmalloc(len, GFP_NOIO | q->bounce_gfp);
290         if (unlikely(buf == NULL)) {
291                 printk(KERN_ERR "could not allocate integrity buffer\n");
292                 return -ENOMEM;
293         }
294 
295         end = (((unsigned long) buf) + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
296         start = ((unsigned long) buf) >> PAGE_SHIFT;
297         nr_pages = end - start;
298 
299         /* Allocate bio integrity payload and integrity vectors */
300         bip = bio_integrity_alloc(bio, GFP_NOIO, nr_pages);
301         if (IS_ERR(bip)) {
302                 printk(KERN_ERR "could not allocate data integrity bioset\n");
303                 kfree(buf);
304                 return PTR_ERR(bip);
305         }
306 
307         bip->bip_flags |= BIP_BLOCK_INTEGRITY;
308         bip->bip_iter.bi_size = len;
309         bip_set_seed(bip, bio->bi_iter.bi_sector);
310 
311         if (bi->flags & BLK_INTEGRITY_IP_CHECKSUM)
312                 bip->bip_flags |= BIP_IP_CHECKSUM;
313 
314         /* Map it */
315         offset = offset_in_page(buf);
316         for (i = 0 ; i < nr_pages ; i++) {
317                 int ret;
318                 bytes = PAGE_SIZE - offset;
319 
320                 if (len <= 0)
321                         break;
322 
323                 if (bytes > len)
324                         bytes = len;
325 
326                 ret = bio_integrity_add_page(bio, virt_to_page(buf),
327                                              bytes, offset);
328 
329                 if (ret == 0)
330                         return 0;
331 
332                 if (ret < bytes)
333                         break;
334 
335                 buf += bytes;
336                 len -= bytes;
337                 offset = 0;
338         }
339 
340         /* Install custom I/O completion handler if read verify is enabled */
341         if (bio_data_dir(bio) == READ) {
342                 bip->bip_end_io = bio->bi_end_io;
343                 bio->bi_end_io = bio_integrity_endio;
344         }
345 
346         /* Auto-generate integrity metadata if this is a write */
347         if (bio_data_dir(bio) == WRITE)
348                 bio_integrity_process(bio, bi->profile->generate_fn);
349 
350         return 0;
351 }
352 EXPORT_SYMBOL(bio_integrity_prep);
353 
354 /**
355  * bio_integrity_verify_fn - Integrity I/O completion worker
356  * @work:       Work struct stored in bio to be verified
357  *
358  * Description: This workqueue function is called to complete a READ
359  * request.  The function verifies the transferred integrity metadata
360  * and then calls the original bio end_io function.
361  */
362 static void bio_integrity_verify_fn(struct work_struct *work)
363 {
364         struct bio_integrity_payload *bip =
365                 container_of(work, struct bio_integrity_payload, bip_work);
366         struct bio *bio = bip->bip_bio;
367         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
368 
369         bio->bi_error = bio_integrity_process(bio, bi->profile->verify_fn);
370 
371         /* Restore original bio completion handler */
372         bio->bi_end_io = bip->bip_end_io;
373         bio_endio(bio);
374 }
375 
376 /**
377  * bio_integrity_endio - Integrity I/O completion function
378  * @bio:        Protected bio
379  * @error:      Pointer to errno
380  *
381  * Description: Completion for integrity I/O
382  *
383  * Normally I/O completion is done in interrupt context.  However,
384  * verifying I/O integrity is a time-consuming task which must be run
385  * in process context.  This function postpones completion
386  * accordingly.
387  */
388 void bio_integrity_endio(struct bio *bio)
389 {
390         struct bio_integrity_payload *bip = bio_integrity(bio);
391 
392         BUG_ON(bip->bip_bio != bio);
393 
394         /* In case of an I/O error there is no point in verifying the
395          * integrity metadata.  Restore original bio end_io handler
396          * and run it.
397          */
398         if (bio->bi_error) {
399                 bio->bi_end_io = bip->bip_end_io;
400                 bio_endio(bio);
401 
402                 return;
403         }
404 
405         INIT_WORK(&bip->bip_work, bio_integrity_verify_fn);
406         queue_work(kintegrityd_wq, &bip->bip_work);
407 }
408 EXPORT_SYMBOL(bio_integrity_endio);
409 
410 /**
411  * bio_integrity_advance - Advance integrity vector
412  * @bio:        bio whose integrity vector to update
413  * @bytes_done: number of data bytes that have been completed
414  *
415  * Description: This function calculates how many integrity bytes the
416  * number of completed data bytes correspond to and advances the
417  * integrity vector accordingly.
418  */
419 void bio_integrity_advance(struct bio *bio, unsigned int bytes_done)
420 {
421         struct bio_integrity_payload *bip = bio_integrity(bio);
422         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
423         unsigned bytes = bio_integrity_bytes(bi, bytes_done >> 9);
424 
425         bvec_iter_advance(bip->bip_vec, &bip->bip_iter, bytes);
426 }
427 EXPORT_SYMBOL(bio_integrity_advance);
428 
429 /**
430  * bio_integrity_trim - Trim integrity vector
431  * @bio:        bio whose integrity vector to update
432  * @offset:     offset to first data sector
433  * @sectors:    number of data sectors
434  *
435  * Description: Used to trim the integrity vector in a cloned bio.
436  * The ivec will be advanced corresponding to 'offset' data sectors
437  * and the length will be truncated corresponding to 'len' data
438  * sectors.
439  */
440 void bio_integrity_trim(struct bio *bio, unsigned int offset,
441                         unsigned int sectors)
442 {
443         struct bio_integrity_payload *bip = bio_integrity(bio);
444         struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
445 
446         bio_integrity_advance(bio, offset << 9);
447         bip->bip_iter.bi_size = bio_integrity_bytes(bi, sectors);
448 }
449 EXPORT_SYMBOL(bio_integrity_trim);
450 
451 /**
452  * bio_integrity_clone - Callback for cloning bios with integrity metadata
453  * @bio:        New bio
454  * @bio_src:    Original bio
455  * @gfp_mask:   Memory allocation mask
456  *
457  * Description: Called to allocate a bip when cloning a bio
458  */
459 int bio_integrity_clone(struct bio *bio, struct bio *bio_src,
460                         gfp_t gfp_mask)
461 {
462         struct bio_integrity_payload *bip_src = bio_integrity(bio_src);
463         struct bio_integrity_payload *bip;
464 
465         BUG_ON(bip_src == NULL);
466 
467         bip = bio_integrity_alloc(bio, gfp_mask, bip_src->bip_vcnt);
468         if (IS_ERR(bip))
469                 return PTR_ERR(bip);
470 
471         memcpy(bip->bip_vec, bip_src->bip_vec,
472                bip_src->bip_vcnt * sizeof(struct bio_vec));
473 
474         bip->bip_vcnt = bip_src->bip_vcnt;
475         bip->bip_iter = bip_src->bip_iter;
476 
477         return 0;
478 }
479 EXPORT_SYMBOL(bio_integrity_clone);
480 
481 int bioset_integrity_create(struct bio_set *bs, int pool_size)
482 {
483         if (bs->bio_integrity_pool)
484                 return 0;
485 
486         bs->bio_integrity_pool = mempool_create_slab_pool(pool_size, bip_slab);
487         if (!bs->bio_integrity_pool)
488                 return -1;
489 
490         bs->bvec_integrity_pool = biovec_create_pool(pool_size);
491         if (!bs->bvec_integrity_pool) {
492                 mempool_destroy(bs->bio_integrity_pool);
493                 return -1;
494         }
495 
496         return 0;
497 }
498 EXPORT_SYMBOL(bioset_integrity_create);
499 
500 void bioset_integrity_free(struct bio_set *bs)
501 {
502         if (bs->bio_integrity_pool)
503                 mempool_destroy(bs->bio_integrity_pool);
504 
505         if (bs->bvec_integrity_pool)
506                 mempool_destroy(bs->bvec_integrity_pool);
507 }
508 EXPORT_SYMBOL(bioset_integrity_free);
509 
510 void __init bio_integrity_init(void)
511 {
512         /*
513          * kintegrityd won't block much but may burn a lot of CPU cycles.
514          * Make it highpri CPU intensive wq with max concurrency of 1.
515          */
516         kintegrityd_wq = alloc_workqueue("kintegrityd", WQ_MEM_RECLAIM |
517                                          WQ_HIGHPRI | WQ_CPU_INTENSIVE, 1);
518         if (!kintegrityd_wq)
519                 panic("Failed to create kintegrityd\n");
520 
521         bip_slab = kmem_cache_create("bio_integrity_payload",
522                                      sizeof(struct bio_integrity_payload) +
523                                      sizeof(struct bio_vec) * BIP_INLINE_VECS,
524                                      0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
525 }
526 

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