Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/block/blk-core.c

  1 /*
  2  * Copyright (C) 1991, 1992 Linus Torvalds
  3  * Copyright (C) 1994,      Karl Keyte: Added support for disk statistics
  4  * Elevator latency, (C) 2000  Andrea Arcangeli <andrea@suse.de> SuSE
  5  * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de>
  6  * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au>
  7  *      -  July2000
  8  * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
  9  */
 10 
 11 /*
 12  * This handles all read/write requests to block devices
 13  */
 14 #include <linux/kernel.h>
 15 #include <linux/module.h>
 16 #include <linux/backing-dev.h>
 17 #include <linux/bio.h>
 18 #include <linux/blkdev.h>
 19 #include <linux/blk-mq.h>
 20 #include <linux/highmem.h>
 21 #include <linux/mm.h>
 22 #include <linux/kernel_stat.h>
 23 #include <linux/string.h>
 24 #include <linux/init.h>
 25 #include <linux/completion.h>
 26 #include <linux/slab.h>
 27 #include <linux/swap.h>
 28 #include <linux/writeback.h>
 29 #include <linux/task_io_accounting_ops.h>
 30 #include <linux/fault-inject.h>
 31 #include <linux/list_sort.h>
 32 #include <linux/delay.h>
 33 #include <linux/ratelimit.h>
 34 #include <linux/pm_runtime.h>
 35 #include <linux/blk-cgroup.h>
 36 
 37 #define CREATE_TRACE_POINTS
 38 #include <trace/events/block.h>
 39 
 40 #include "blk.h"
 41 #include "blk-mq.h"
 42 #include "blk-wbt.h"
 43 
 44 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
 45 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
 46 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
 47 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split);
 48 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
 49 
 50 DEFINE_IDA(blk_queue_ida);
 51 
 52 /*
 53  * For the allocated request tables
 54  */
 55 struct kmem_cache *request_cachep;
 56 
 57 /*
 58  * For queue allocation
 59  */
 60 struct kmem_cache *blk_requestq_cachep;
 61 
 62 /*
 63  * Controlling structure to kblockd
 64  */
 65 static struct workqueue_struct *kblockd_workqueue;
 66 
 67 static void blk_clear_congested(struct request_list *rl, int sync)
 68 {
 69 #ifdef CONFIG_CGROUP_WRITEBACK
 70         clear_wb_congested(rl->blkg->wb_congested, sync);
 71 #else
 72         /*
 73          * If !CGROUP_WRITEBACK, all blkg's map to bdi->wb and we shouldn't
 74          * flip its congestion state for events on other blkcgs.
 75          */
 76         if (rl == &rl->q->root_rl)
 77                 clear_wb_congested(rl->q->backing_dev_info.wb.congested, sync);
 78 #endif
 79 }
 80 
 81 static void blk_set_congested(struct request_list *rl, int sync)
 82 {
 83 #ifdef CONFIG_CGROUP_WRITEBACK
 84         set_wb_congested(rl->blkg->wb_congested, sync);
 85 #else
 86         /* see blk_clear_congested() */
 87         if (rl == &rl->q->root_rl)
 88                 set_wb_congested(rl->q->backing_dev_info.wb.congested, sync);
 89 #endif
 90 }
 91 
 92 void blk_queue_congestion_threshold(struct request_queue *q)
 93 {
 94         int nr;
 95 
 96         nr = q->nr_requests - (q->nr_requests / 8) + 1;
 97         if (nr > q->nr_requests)
 98                 nr = q->nr_requests;
 99         q->nr_congestion_on = nr;
100 
101         nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
102         if (nr < 1)
103                 nr = 1;
104         q->nr_congestion_off = nr;
105 }
106 
107 /**
108  * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
109  * @bdev:       device
110  *
111  * Locates the passed device's request queue and returns the address of its
112  * backing_dev_info.  This function can only be called if @bdev is opened
113  * and the return value is never NULL.
114  */
115 struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
116 {
117         struct request_queue *q = bdev_get_queue(bdev);
118 
119         return &q->backing_dev_info;
120 }
121 EXPORT_SYMBOL(blk_get_backing_dev_info);
122 
123 void blk_rq_init(struct request_queue *q, struct request *rq)
124 {
125         memset(rq, 0, sizeof(*rq));
126 
127         INIT_LIST_HEAD(&rq->queuelist);
128         INIT_LIST_HEAD(&rq->timeout_list);
129         rq->cpu = -1;
130         rq->q = q;
131         rq->__sector = (sector_t) -1;
132         INIT_HLIST_NODE(&rq->hash);
133         RB_CLEAR_NODE(&rq->rb_node);
134         rq->cmd = rq->__cmd;
135         rq->cmd_len = BLK_MAX_CDB;
136         rq->tag = -1;
137         rq->start_time = jiffies;
138         set_start_time_ns(rq);
139         rq->part = NULL;
140 }
141 EXPORT_SYMBOL(blk_rq_init);
142 
143 static void req_bio_endio(struct request *rq, struct bio *bio,
144                           unsigned int nbytes, int error)
145 {
146         if (error)
147                 bio->bi_error = error;
148 
149         if (unlikely(rq->rq_flags & RQF_QUIET))
150                 bio_set_flag(bio, BIO_QUIET);
151 
152         bio_advance(bio, nbytes);
153 
154         /* don't actually finish bio if it's part of flush sequence */
155         if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ))
156                 bio_endio(bio);
157 }
158 
159 void blk_dump_rq_flags(struct request *rq, char *msg)
160 {
161         int bit;
162 
163         printk(KERN_INFO "%s: dev %s: type=%x, flags=%llx\n", msg,
164                 rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type,
165                 (unsigned long long) rq->cmd_flags);
166 
167         printk(KERN_INFO "  sector %llu, nr/cnr %u/%u\n",
168                (unsigned long long)blk_rq_pos(rq),
169                blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
170         printk(KERN_INFO "  bio %p, biotail %p, len %u\n",
171                rq->bio, rq->biotail, blk_rq_bytes(rq));
172 
173         if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
174                 printk(KERN_INFO "  cdb: ");
175                 for (bit = 0; bit < BLK_MAX_CDB; bit++)
176                         printk("%02x ", rq->cmd[bit]);
177                 printk("\n");
178         }
179 }
180 EXPORT_SYMBOL(blk_dump_rq_flags);
181 
182 static void blk_delay_work(struct work_struct *work)
183 {
184         struct request_queue *q;
185 
186         q = container_of(work, struct request_queue, delay_work.work);
187         spin_lock_irq(q->queue_lock);
188         __blk_run_queue(q);
189         spin_unlock_irq(q->queue_lock);
190 }
191 
192 /**
193  * blk_delay_queue - restart queueing after defined interval
194  * @q:          The &struct request_queue in question
195  * @msecs:      Delay in msecs
196  *
197  * Description:
198  *   Sometimes queueing needs to be postponed for a little while, to allow
199  *   resources to come back. This function will make sure that queueing is
200  *   restarted around the specified time. Queue lock must be held.
201  */
202 void blk_delay_queue(struct request_queue *q, unsigned long msecs)
203 {
204         if (likely(!blk_queue_dead(q)))
205                 queue_delayed_work(kblockd_workqueue, &q->delay_work,
206                                    msecs_to_jiffies(msecs));
207 }
208 EXPORT_SYMBOL(blk_delay_queue);
209 
210 /**
211  * blk_start_queue_async - asynchronously restart a previously stopped queue
212  * @q:    The &struct request_queue in question
213  *
214  * Description:
215  *   blk_start_queue_async() will clear the stop flag on the queue, and
216  *   ensure that the request_fn for the queue is run from an async
217  *   context.
218  **/
219 void blk_start_queue_async(struct request_queue *q)
220 {
221         queue_flag_clear(QUEUE_FLAG_STOPPED, q);
222         blk_run_queue_async(q);
223 }
224 EXPORT_SYMBOL(blk_start_queue_async);
225 
226 /**
227  * blk_start_queue - restart a previously stopped queue
228  * @q:    The &struct request_queue in question
229  *
230  * Description:
231  *   blk_start_queue() will clear the stop flag on the queue, and call
232  *   the request_fn for the queue if it was in a stopped state when
233  *   entered. Also see blk_stop_queue(). Queue lock must be held.
234  **/
235 void blk_start_queue(struct request_queue *q)
236 {
237         WARN_ON(!irqs_disabled());
238 
239         queue_flag_clear(QUEUE_FLAG_STOPPED, q);
240         __blk_run_queue(q);
241 }
242 EXPORT_SYMBOL(blk_start_queue);
243 
244 /**
245  * blk_stop_queue - stop a queue
246  * @q:    The &struct request_queue in question
247  *
248  * Description:
249  *   The Linux block layer assumes that a block driver will consume all
250  *   entries on the request queue when the request_fn strategy is called.
251  *   Often this will not happen, because of hardware limitations (queue
252  *   depth settings). If a device driver gets a 'queue full' response,
253  *   or if it simply chooses not to queue more I/O at one point, it can
254  *   call this function to prevent the request_fn from being called until
255  *   the driver has signalled it's ready to go again. This happens by calling
256  *   blk_start_queue() to restart queue operations. Queue lock must be held.
257  **/
258 void blk_stop_queue(struct request_queue *q)
259 {
260         cancel_delayed_work(&q->delay_work);
261         queue_flag_set(QUEUE_FLAG_STOPPED, q);
262 }
263 EXPORT_SYMBOL(blk_stop_queue);
264 
265 /**
266  * blk_sync_queue - cancel any pending callbacks on a queue
267  * @q: the queue
268  *
269  * Description:
270  *     The block layer may perform asynchronous callback activity
271  *     on a queue, such as calling the unplug function after a timeout.
272  *     A block device may call blk_sync_queue to ensure that any
273  *     such activity is cancelled, thus allowing it to release resources
274  *     that the callbacks might use. The caller must already have made sure
275  *     that its ->make_request_fn will not re-add plugging prior to calling
276  *     this function.
277  *
278  *     This function does not cancel any asynchronous activity arising
279  *     out of elevator or throttling code. That would require elevator_exit()
280  *     and blkcg_exit_queue() to be called with queue lock initialized.
281  *
282  */
283 void blk_sync_queue(struct request_queue *q)
284 {
285         del_timer_sync(&q->timeout);
286 
287         if (q->mq_ops) {
288                 struct blk_mq_hw_ctx *hctx;
289                 int i;
290 
291                 queue_for_each_hw_ctx(q, hctx, i) {
292                         cancel_work_sync(&hctx->run_work);
293                         cancel_delayed_work_sync(&hctx->delay_work);
294                 }
295         } else {
296                 cancel_delayed_work_sync(&q->delay_work);
297         }
298 }
299 EXPORT_SYMBOL(blk_sync_queue);
300 
301 /**
302  * __blk_run_queue_uncond - run a queue whether or not it has been stopped
303  * @q:  The queue to run
304  *
305  * Description:
306  *    Invoke request handling on a queue if there are any pending requests.
307  *    May be used to restart request handling after a request has completed.
308  *    This variant runs the queue whether or not the queue has been
309  *    stopped. Must be called with the queue lock held and interrupts
310  *    disabled. See also @blk_run_queue.
311  */
312 inline void __blk_run_queue_uncond(struct request_queue *q)
313 {
314         if (unlikely(blk_queue_dead(q)))
315                 return;
316 
317         /*
318          * Some request_fn implementations, e.g. scsi_request_fn(), unlock
319          * the queue lock internally. As a result multiple threads may be
320          * running such a request function concurrently. Keep track of the
321          * number of active request_fn invocations such that blk_drain_queue()
322          * can wait until all these request_fn calls have finished.
323          */
324         q->request_fn_active++;
325         q->request_fn(q);
326         q->request_fn_active--;
327 }
328 EXPORT_SYMBOL_GPL(__blk_run_queue_uncond);
329 
330 /**
331  * __blk_run_queue - run a single device queue
332  * @q:  The queue to run
333  *
334  * Description:
335  *    See @blk_run_queue. This variant must be called with the queue lock
336  *    held and interrupts disabled.
337  */
338 void __blk_run_queue(struct request_queue *q)
339 {
340         if (unlikely(blk_queue_stopped(q)))
341                 return;
342 
343         __blk_run_queue_uncond(q);
344 }
345 EXPORT_SYMBOL(__blk_run_queue);
346 
347 /**
348  * blk_run_queue_async - run a single device queue in workqueue context
349  * @q:  The queue to run
350  *
351  * Description:
352  *    Tells kblockd to perform the equivalent of @blk_run_queue on behalf
353  *    of us. The caller must hold the queue lock.
354  */
355 void blk_run_queue_async(struct request_queue *q)
356 {
357         if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q)))
358                 mod_delayed_work(kblockd_workqueue, &q->delay_work, 0);
359 }
360 EXPORT_SYMBOL(blk_run_queue_async);
361 
362 /**
363  * blk_run_queue - run a single device queue
364  * @q: The queue to run
365  *
366  * Description:
367  *    Invoke request handling on this queue, if it has pending work to do.
368  *    May be used to restart queueing when a request has completed.
369  */
370 void blk_run_queue(struct request_queue *q)
371 {
372         unsigned long flags;
373 
374         spin_lock_irqsave(q->queue_lock, flags);
375         __blk_run_queue(q);
376         spin_unlock_irqrestore(q->queue_lock, flags);
377 }
378 EXPORT_SYMBOL(blk_run_queue);
379 
380 void blk_put_queue(struct request_queue *q)
381 {
382         kobject_put(&q->kobj);
383 }
384 EXPORT_SYMBOL(blk_put_queue);
385 
386 /**
387  * __blk_drain_queue - drain requests from request_queue
388  * @q: queue to drain
389  * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
390  *
391  * Drain requests from @q.  If @drain_all is set, all requests are drained.
392  * If not, only ELVPRIV requests are drained.  The caller is responsible
393  * for ensuring that no new requests which need to be drained are queued.
394  */
395 static void __blk_drain_queue(struct request_queue *q, bool drain_all)
396         __releases(q->queue_lock)
397         __acquires(q->queue_lock)
398 {
399         int i;
400 
401         lockdep_assert_held(q->queue_lock);
402 
403         while (true) {
404                 bool drain = false;
405 
406                 /*
407                  * The caller might be trying to drain @q before its
408                  * elevator is initialized.
409                  */
410                 if (q->elevator)
411                         elv_drain_elevator(q);
412 
413                 blkcg_drain_queue(q);
414 
415                 /*
416                  * This function might be called on a queue which failed
417                  * driver init after queue creation or is not yet fully
418                  * active yet.  Some drivers (e.g. fd and loop) get unhappy
419                  * in such cases.  Kick queue iff dispatch queue has
420                  * something on it and @q has request_fn set.
421                  */
422                 if (!list_empty(&q->queue_head) && q->request_fn)
423                         __blk_run_queue(q);
424 
425                 drain |= q->nr_rqs_elvpriv;
426                 drain |= q->request_fn_active;
427 
428                 /*
429                  * Unfortunately, requests are queued at and tracked from
430                  * multiple places and there's no single counter which can
431                  * be drained.  Check all the queues and counters.
432                  */
433                 if (drain_all) {
434                         struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
435                         drain |= !list_empty(&q->queue_head);
436                         for (i = 0; i < 2; i++) {
437                                 drain |= q->nr_rqs[i];
438                                 drain |= q->in_flight[i];
439                                 if (fq)
440                                     drain |= !list_empty(&fq->flush_queue[i]);
441                         }
442                 }
443 
444                 if (!drain)
445                         break;
446 
447                 spin_unlock_irq(q->queue_lock);
448 
449                 msleep(10);
450 
451                 spin_lock_irq(q->queue_lock);
452         }
453 
454         /*
455          * With queue marked dead, any woken up waiter will fail the
456          * allocation path, so the wakeup chaining is lost and we're
457          * left with hung waiters. We need to wake up those waiters.
458          */
459         if (q->request_fn) {
460                 struct request_list *rl;
461 
462                 blk_queue_for_each_rl(rl, q)
463                         for (i = 0; i < ARRAY_SIZE(rl->wait); i++)
464                                 wake_up_all(&rl->wait[i]);
465         }
466 }
467 
468 /**
469  * blk_queue_bypass_start - enter queue bypass mode
470  * @q: queue of interest
471  *
472  * In bypass mode, only the dispatch FIFO queue of @q is used.  This
473  * function makes @q enter bypass mode and drains all requests which were
474  * throttled or issued before.  On return, it's guaranteed that no request
475  * is being throttled or has ELVPRIV set and blk_queue_bypass() %true
476  * inside queue or RCU read lock.
477  */
478 void blk_queue_bypass_start(struct request_queue *q)
479 {
480         spin_lock_irq(q->queue_lock);
481         q->bypass_depth++;
482         queue_flag_set(QUEUE_FLAG_BYPASS, q);
483         spin_unlock_irq(q->queue_lock);
484 
485         /*
486          * Queues start drained.  Skip actual draining till init is
487          * complete.  This avoids lenghty delays during queue init which
488          * can happen many times during boot.
489          */
490         if (blk_queue_init_done(q)) {
491                 spin_lock_irq(q->queue_lock);
492                 __blk_drain_queue(q, false);
493                 spin_unlock_irq(q->queue_lock);
494 
495                 /* ensure blk_queue_bypass() is %true inside RCU read lock */
496                 synchronize_rcu();
497         }
498 }
499 EXPORT_SYMBOL_GPL(blk_queue_bypass_start);
500 
501 /**
502  * blk_queue_bypass_end - leave queue bypass mode
503  * @q: queue of interest
504  *
505  * Leave bypass mode and restore the normal queueing behavior.
506  */
507 void blk_queue_bypass_end(struct request_queue *q)
508 {
509         spin_lock_irq(q->queue_lock);
510         if (!--q->bypass_depth)
511                 queue_flag_clear(QUEUE_FLAG_BYPASS, q);
512         WARN_ON_ONCE(q->bypass_depth < 0);
513         spin_unlock_irq(q->queue_lock);
514 }
515 EXPORT_SYMBOL_GPL(blk_queue_bypass_end);
516 
517 void blk_set_queue_dying(struct request_queue *q)
518 {
519         spin_lock_irq(q->queue_lock);
520         queue_flag_set(QUEUE_FLAG_DYING, q);
521         spin_unlock_irq(q->queue_lock);
522 
523         if (q->mq_ops)
524                 blk_mq_wake_waiters(q);
525         else {
526                 struct request_list *rl;
527 
528                 blk_queue_for_each_rl(rl, q) {
529                         if (rl->rq_pool) {
530                                 wake_up(&rl->wait[BLK_RW_SYNC]);
531                                 wake_up(&rl->wait[BLK_RW_ASYNC]);
532                         }
533                 }
534         }
535 }
536 EXPORT_SYMBOL_GPL(blk_set_queue_dying);
537 
538 /**
539  * blk_cleanup_queue - shutdown a request queue
540  * @q: request queue to shutdown
541  *
542  * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
543  * put it.  All future requests will be failed immediately with -ENODEV.
544  */
545 void blk_cleanup_queue(struct request_queue *q)
546 {
547         spinlock_t *lock = q->queue_lock;
548 
549         /* mark @q DYING, no new request or merges will be allowed afterwards */
550         mutex_lock(&q->sysfs_lock);
551         blk_set_queue_dying(q);
552         spin_lock_irq(lock);
553 
554         /*
555          * A dying queue is permanently in bypass mode till released.  Note
556          * that, unlike blk_queue_bypass_start(), we aren't performing
557          * synchronize_rcu() after entering bypass mode to avoid the delay
558          * as some drivers create and destroy a lot of queues while
559          * probing.  This is still safe because blk_release_queue() will be
560          * called only after the queue refcnt drops to zero and nothing,
561          * RCU or not, would be traversing the queue by then.
562          */
563         q->bypass_depth++;
564         queue_flag_set(QUEUE_FLAG_BYPASS, q);
565 
566         queue_flag_set(QUEUE_FLAG_NOMERGES, q);
567         queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
568         queue_flag_set(QUEUE_FLAG_DYING, q);
569         spin_unlock_irq(lock);
570         mutex_unlock(&q->sysfs_lock);
571 
572         /*
573          * Drain all requests queued before DYING marking. Set DEAD flag to
574          * prevent that q->request_fn() gets invoked after draining finished.
575          */
576         blk_freeze_queue(q);
577         spin_lock_irq(lock);
578         if (!q->mq_ops)
579                 __blk_drain_queue(q, true);
580         queue_flag_set(QUEUE_FLAG_DEAD, q);
581         spin_unlock_irq(lock);
582 
583         /* for synchronous bio-based driver finish in-flight integrity i/o */
584         blk_flush_integrity();
585 
586         /* @q won't process any more request, flush async actions */
587         del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer);
588         blk_sync_queue(q);
589 
590         if (q->mq_ops)
591                 blk_mq_free_queue(q);
592         percpu_ref_exit(&q->q_usage_counter);
593 
594         spin_lock_irq(lock);
595         if (q->queue_lock != &q->__queue_lock)
596                 q->queue_lock = &q->__queue_lock;
597         spin_unlock_irq(lock);
598 
599         bdi_unregister(&q->backing_dev_info);
600 
601         /* @q is and will stay empty, shutdown and put */
602         blk_put_queue(q);
603 }
604 EXPORT_SYMBOL(blk_cleanup_queue);
605 
606 /* Allocate memory local to the request queue */
607 static void *alloc_request_struct(gfp_t gfp_mask, void *data)
608 {
609         int nid = (int)(long)data;
610         return kmem_cache_alloc_node(request_cachep, gfp_mask, nid);
611 }
612 
613 static void free_request_struct(void *element, void *unused)
614 {
615         kmem_cache_free(request_cachep, element);
616 }
617 
618 int blk_init_rl(struct request_list *rl, struct request_queue *q,
619                 gfp_t gfp_mask)
620 {
621         if (unlikely(rl->rq_pool))
622                 return 0;
623 
624         rl->q = q;
625         rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
626         rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
627         init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
628         init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
629 
630         rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, alloc_request_struct,
631                                           free_request_struct,
632                                           (void *)(long)q->node, gfp_mask,
633                                           q->node);
634         if (!rl->rq_pool)
635                 return -ENOMEM;
636 
637         return 0;
638 }
639 
640 void blk_exit_rl(struct request_list *rl)
641 {
642         if (rl->rq_pool)
643                 mempool_destroy(rl->rq_pool);
644 }
645 
646 struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
647 {
648         return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE);
649 }
650 EXPORT_SYMBOL(blk_alloc_queue);
651 
652 int blk_queue_enter(struct request_queue *q, bool nowait)
653 {
654         while (true) {
655                 int ret;
656 
657                 if (percpu_ref_tryget_live(&q->q_usage_counter))
658                         return 0;
659 
660                 if (nowait)
661                         return -EBUSY;
662 
663                 ret = wait_event_interruptible(q->mq_freeze_wq,
664                                 !atomic_read(&q->mq_freeze_depth) ||
665                                 blk_queue_dying(q));
666                 if (blk_queue_dying(q))
667                         return -ENODEV;
668                 if (ret)
669                         return ret;
670         }
671 }
672 
673 void blk_queue_exit(struct request_queue *q)
674 {
675         percpu_ref_put(&q->q_usage_counter);
676 }
677 
678 static void blk_queue_usage_counter_release(struct percpu_ref *ref)
679 {
680         struct request_queue *q =
681                 container_of(ref, struct request_queue, q_usage_counter);
682 
683         wake_up_all(&q->mq_freeze_wq);
684 }
685 
686 static void blk_rq_timed_out_timer(unsigned long data)
687 {
688         struct request_queue *q = (struct request_queue *)data;
689 
690         kblockd_schedule_work(&q->timeout_work);
691 }
692 
693 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
694 {
695         struct request_queue *q;
696         int err;
697 
698         q = kmem_cache_alloc_node(blk_requestq_cachep,
699                                 gfp_mask | __GFP_ZERO, node_id);
700         if (!q)
701                 return NULL;
702 
703         q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask);
704         if (q->id < 0)
705                 goto fail_q;
706 
707         q->bio_split = bioset_create(BIO_POOL_SIZE, 0);
708         if (!q->bio_split)
709                 goto fail_id;
710 
711         q->backing_dev_info.ra_pages =
712                         (VM_MAX_READAHEAD * 1024) / PAGE_SIZE;
713         q->backing_dev_info.capabilities = BDI_CAP_CGROUP_WRITEBACK;
714         q->backing_dev_info.name = "block";
715         q->node = node_id;
716 
717         err = bdi_init(&q->backing_dev_info);
718         if (err)
719                 goto fail_split;
720 
721         setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
722                     laptop_mode_timer_fn, (unsigned long) q);
723         setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
724         INIT_LIST_HEAD(&q->queue_head);
725         INIT_LIST_HEAD(&q->timeout_list);
726         INIT_LIST_HEAD(&q->icq_list);
727 #ifdef CONFIG_BLK_CGROUP
728         INIT_LIST_HEAD(&q->blkg_list);
729 #endif
730         INIT_DELAYED_WORK(&q->delay_work, blk_delay_work);
731 
732         kobject_init(&q->kobj, &blk_queue_ktype);
733 
734         mutex_init(&q->sysfs_lock);
735         spin_lock_init(&q->__queue_lock);
736 
737         /*
738          * By default initialize queue_lock to internal lock and driver can
739          * override it later if need be.
740          */
741         q->queue_lock = &q->__queue_lock;
742 
743         /*
744          * A queue starts its life with bypass turned on to avoid
745          * unnecessary bypass on/off overhead and nasty surprises during
746          * init.  The initial bypass will be finished when the queue is
747          * registered by blk_register_queue().
748          */
749         q->bypass_depth = 1;
750         __set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags);
751 
752         init_waitqueue_head(&q->mq_freeze_wq);
753 
754         /*
755          * Init percpu_ref in atomic mode so that it's faster to shutdown.
756          * See blk_register_queue() for details.
757          */
758         if (percpu_ref_init(&q->q_usage_counter,
759                                 blk_queue_usage_counter_release,
760                                 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
761                 goto fail_bdi;
762 
763         if (blkcg_init_queue(q))
764                 goto fail_ref;
765 
766         return q;
767 
768 fail_ref:
769         percpu_ref_exit(&q->q_usage_counter);
770 fail_bdi:
771         bdi_destroy(&q->backing_dev_info);
772 fail_split:
773         bioset_free(q->bio_split);
774 fail_id:
775         ida_simple_remove(&blk_queue_ida, q->id);
776 fail_q:
777         kmem_cache_free(blk_requestq_cachep, q);
778         return NULL;
779 }
780 EXPORT_SYMBOL(blk_alloc_queue_node);
781 
782 /**
783  * blk_init_queue  - prepare a request queue for use with a block device
784  * @rfn:  The function to be called to process requests that have been
785  *        placed on the queue.
786  * @lock: Request queue spin lock
787  *
788  * Description:
789  *    If a block device wishes to use the standard request handling procedures,
790  *    which sorts requests and coalesces adjacent requests, then it must
791  *    call blk_init_queue().  The function @rfn will be called when there
792  *    are requests on the queue that need to be processed.  If the device
793  *    supports plugging, then @rfn may not be called immediately when requests
794  *    are available on the queue, but may be called at some time later instead.
795  *    Plugged queues are generally unplugged when a buffer belonging to one
796  *    of the requests on the queue is needed, or due to memory pressure.
797  *
798  *    @rfn is not required, or even expected, to remove all requests off the
799  *    queue, but only as many as it can handle at a time.  If it does leave
800  *    requests on the queue, it is responsible for arranging that the requests
801  *    get dealt with eventually.
802  *
803  *    The queue spin lock must be held while manipulating the requests on the
804  *    request queue; this lock will be taken also from interrupt context, so irq
805  *    disabling is needed for it.
806  *
807  *    Function returns a pointer to the initialized request queue, or %NULL if
808  *    it didn't succeed.
809  *
810  * Note:
811  *    blk_init_queue() must be paired with a blk_cleanup_queue() call
812  *    when the block device is deactivated (such as at module unload).
813  **/
814 
815 struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
816 {
817         return blk_init_queue_node(rfn, lock, NUMA_NO_NODE);
818 }
819 EXPORT_SYMBOL(blk_init_queue);
820 
821 struct request_queue *
822 blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
823 {
824         struct request_queue *uninit_q, *q;
825 
826         uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id);
827         if (!uninit_q)
828                 return NULL;
829 
830         q = blk_init_allocated_queue(uninit_q, rfn, lock);
831         if (!q)
832                 blk_cleanup_queue(uninit_q);
833 
834         return q;
835 }
836 EXPORT_SYMBOL(blk_init_queue_node);
837 
838 static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio);
839 
840 struct request_queue *
841 blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
842                          spinlock_t *lock)
843 {
844         if (!q)
845                 return NULL;
846 
847         q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, 0);
848         if (!q->fq)
849                 return NULL;
850 
851         if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))
852                 goto fail;
853 
854         INIT_WORK(&q->timeout_work, blk_timeout_work);
855         q->request_fn           = rfn;
856         q->prep_rq_fn           = NULL;
857         q->unprep_rq_fn         = NULL;
858         q->queue_flags          |= QUEUE_FLAG_DEFAULT;
859 
860         /* Override internal queue lock with supplied lock pointer */
861         if (lock)
862                 q->queue_lock           = lock;
863 
864         /*
865          * This also sets hw/phys segments, boundary and size
866          */
867         blk_queue_make_request(q, blk_queue_bio);
868 
869         q->sg_reserved_size = INT_MAX;
870 
871         /* Protect q->elevator from elevator_change */
872         mutex_lock(&q->sysfs_lock);
873 
874         /* init elevator */
875         if (elevator_init(q, NULL)) {
876                 mutex_unlock(&q->sysfs_lock);
877                 goto fail;
878         }
879 
880         mutex_unlock(&q->sysfs_lock);
881 
882         return q;
883 
884 fail:
885         blk_free_flush_queue(q->fq);
886         wbt_exit(q);
887         return NULL;
888 }
889 EXPORT_SYMBOL(blk_init_allocated_queue);
890 
891 bool blk_get_queue(struct request_queue *q)
892 {
893         if (likely(!blk_queue_dying(q))) {
894                 __blk_get_queue(q);
895                 return true;
896         }
897 
898         return false;
899 }
900 EXPORT_SYMBOL(blk_get_queue);
901 
902 static inline void blk_free_request(struct request_list *rl, struct request *rq)
903 {
904         if (rq->rq_flags & RQF_ELVPRIV) {
905                 elv_put_request(rl->q, rq);
906                 if (rq->elv.icq)
907                         put_io_context(rq->elv.icq->ioc);
908         }
909 
910         mempool_free(rq, rl->rq_pool);
911 }
912 
913 /*
914  * ioc_batching returns true if the ioc is a valid batching request and
915  * should be given priority access to a request.
916  */
917 static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
918 {
919         if (!ioc)
920                 return 0;
921 
922         /*
923          * Make sure the process is able to allocate at least 1 request
924          * even if the batch times out, otherwise we could theoretically
925          * lose wakeups.
926          */
927         return ioc->nr_batch_requests == q->nr_batching ||
928                 (ioc->nr_batch_requests > 0
929                 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
930 }
931 
932 /*
933  * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
934  * will cause the process to be a "batcher" on all queues in the system. This
935  * is the behaviour we want though - once it gets a wakeup it should be given
936  * a nice run.
937  */
938 static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
939 {
940         if (!ioc || ioc_batching(q, ioc))
941                 return;
942 
943         ioc->nr_batch_requests = q->nr_batching;
944         ioc->last_waited = jiffies;
945 }
946 
947 static void __freed_request(struct request_list *rl, int sync)
948 {
949         struct request_queue *q = rl->q;
950 
951         if (rl->count[sync] < queue_congestion_off_threshold(q))
952                 blk_clear_congested(rl, sync);
953 
954         if (rl->count[sync] + 1 <= q->nr_requests) {
955                 if (waitqueue_active(&rl->wait[sync]))
956                         wake_up(&rl->wait[sync]);
957 
958                 blk_clear_rl_full(rl, sync);
959         }
960 }
961 
962 /*
963  * A request has just been released.  Account for it, update the full and
964  * congestion status, wake up any waiters.   Called under q->queue_lock.
965  */
966 static void freed_request(struct request_list *rl, bool sync,
967                 req_flags_t rq_flags)
968 {
969         struct request_queue *q = rl->q;
970 
971         q->nr_rqs[sync]--;
972         rl->count[sync]--;
973         if (rq_flags & RQF_ELVPRIV)
974                 q->nr_rqs_elvpriv--;
975 
976         __freed_request(rl, sync);
977 
978         if (unlikely(rl->starved[sync ^ 1]))
979                 __freed_request(rl, sync ^ 1);
980 }
981 
982 int blk_update_nr_requests(struct request_queue *q, unsigned int nr)
983 {
984         struct request_list *rl;
985         int on_thresh, off_thresh;
986 
987         spin_lock_irq(q->queue_lock);
988         q->nr_requests = nr;
989         blk_queue_congestion_threshold(q);
990         on_thresh = queue_congestion_on_threshold(q);
991         off_thresh = queue_congestion_off_threshold(q);
992 
993         blk_queue_for_each_rl(rl, q) {
994                 if (rl->count[BLK_RW_SYNC] >= on_thresh)
995                         blk_set_congested(rl, BLK_RW_SYNC);
996                 else if (rl->count[BLK_RW_SYNC] < off_thresh)
997                         blk_clear_congested(rl, BLK_RW_SYNC);
998 
999                 if (rl->count[BLK_RW_ASYNC] >= on_thresh)
1000                         blk_set_congested(rl, BLK_RW_ASYNC);
1001                 else if (rl->count[BLK_RW_ASYNC] < off_thresh)
1002                         blk_clear_congested(rl, BLK_RW_ASYNC);
1003 
1004                 if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
1005                         blk_set_rl_full(rl, BLK_RW_SYNC);
1006                 } else {
1007                         blk_clear_rl_full(rl, BLK_RW_SYNC);
1008                         wake_up(&rl->wait[BLK_RW_SYNC]);
1009                 }
1010 
1011                 if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
1012                         blk_set_rl_full(rl, BLK_RW_ASYNC);
1013                 } else {
1014                         blk_clear_rl_full(rl, BLK_RW_ASYNC);
1015                         wake_up(&rl->wait[BLK_RW_ASYNC]);
1016                 }
1017         }
1018 
1019         spin_unlock_irq(q->queue_lock);
1020         return 0;
1021 }
1022 
1023 /*
1024  * Determine if elevator data should be initialized when allocating the
1025  * request associated with @bio.
1026  */
1027 static bool blk_rq_should_init_elevator(struct bio *bio)
1028 {
1029         if (!bio)
1030                 return true;
1031 
1032         /*
1033          * Flush requests do not use the elevator so skip initialization.
1034          * This allows a request to share the flush and elevator data.
1035          */
1036         if (bio->bi_opf & (REQ_PREFLUSH | REQ_FUA))
1037                 return false;
1038 
1039         return true;
1040 }
1041 
1042 /**
1043  * rq_ioc - determine io_context for request allocation
1044  * @bio: request being allocated is for this bio (can be %NULL)
1045  *
1046  * Determine io_context to use for request allocation for @bio.  May return
1047  * %NULL if %current->io_context doesn't exist.
1048  */
1049 static struct io_context *rq_ioc(struct bio *bio)
1050 {
1051 #ifdef CONFIG_BLK_CGROUP
1052         if (bio && bio->bi_ioc)
1053                 return bio->bi_ioc;
1054 #endif
1055         return current->io_context;
1056 }
1057 
1058 /**
1059  * __get_request - get a free request
1060  * @rl: request list to allocate from
1061  * @op: operation and flags
1062  * @bio: bio to allocate request for (can be %NULL)
1063  * @gfp_mask: allocation mask
1064  *
1065  * Get a free request from @q.  This function may fail under memory
1066  * pressure or if @q is dead.
1067  *
1068  * Must be called with @q->queue_lock held and,
1069  * Returns ERR_PTR on failure, with @q->queue_lock held.
1070  * Returns request pointer on success, with @q->queue_lock *not held*.
1071  */
1072 static struct request *__get_request(struct request_list *rl, unsigned int op,
1073                 struct bio *bio, gfp_t gfp_mask)
1074 {
1075         struct request_queue *q = rl->q;
1076         struct request *rq;
1077         struct elevator_type *et = q->elevator->type;
1078         struct io_context *ioc = rq_ioc(bio);
1079         struct io_cq *icq = NULL;
1080         const bool is_sync = op_is_sync(op);
1081         int may_queue;
1082         req_flags_t rq_flags = RQF_ALLOCED;
1083 
1084         if (unlikely(blk_queue_dying(q)))
1085                 return ERR_PTR(-ENODEV);
1086 
1087         may_queue = elv_may_queue(q, op);
1088         if (may_queue == ELV_MQUEUE_NO)
1089                 goto rq_starved;
1090 
1091         if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
1092                 if (rl->count[is_sync]+1 >= q->nr_requests) {
1093                         /*
1094                          * The queue will fill after this allocation, so set
1095                          * it as full, and mark this process as "batching".
1096                          * This process will be allowed to complete a batch of
1097                          * requests, others will be blocked.
1098                          */
1099                         if (!blk_rl_full(rl, is_sync)) {
1100                                 ioc_set_batching(q, ioc);
1101                                 blk_set_rl_full(rl, is_sync);
1102                         } else {
1103                                 if (may_queue != ELV_MQUEUE_MUST
1104                                                 && !ioc_batching(q, ioc)) {
1105                                         /*
1106                                          * The queue is full and the allocating
1107                                          * process is not a "batcher", and not
1108                                          * exempted by the IO scheduler
1109                                          */
1110                                         return ERR_PTR(-ENOMEM);
1111                                 }
1112                         }
1113                 }
1114                 blk_set_congested(rl, is_sync);
1115         }
1116 
1117         /*
1118          * Only allow batching queuers to allocate up to 50% over the defined
1119          * limit of requests, otherwise we could have thousands of requests
1120          * allocated with any setting of ->nr_requests
1121          */
1122         if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
1123                 return ERR_PTR(-ENOMEM);
1124 
1125         q->nr_rqs[is_sync]++;
1126         rl->count[is_sync]++;
1127         rl->starved[is_sync] = 0;
1128 
1129         /*
1130          * Decide whether the new request will be managed by elevator.  If
1131          * so, mark @rq_flags and increment elvpriv.  Non-zero elvpriv will
1132          * prevent the current elevator from being destroyed until the new
1133          * request is freed.  This guarantees icq's won't be destroyed and
1134          * makes creating new ones safe.
1135          *
1136          * Also, lookup icq while holding queue_lock.  If it doesn't exist,
1137          * it will be created after releasing queue_lock.
1138          */
1139         if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) {
1140                 rq_flags |= RQF_ELVPRIV;
1141                 q->nr_rqs_elvpriv++;
1142                 if (et->icq_cache && ioc)
1143                         icq = ioc_lookup_icq(ioc, q);
1144         }
1145 
1146         if (blk_queue_io_stat(q))
1147                 rq_flags |= RQF_IO_STAT;
1148         spin_unlock_irq(q->queue_lock);
1149 
1150         /* allocate and init request */
1151         rq = mempool_alloc(rl->rq_pool, gfp_mask);
1152         if (!rq)
1153                 goto fail_alloc;
1154 
1155         blk_rq_init(q, rq);
1156         blk_rq_set_rl(rq, rl);
1157         blk_rq_set_prio(rq, ioc);
1158         rq->cmd_flags = op;
1159         rq->rq_flags = rq_flags;
1160 
1161         /* init elvpriv */
1162         if (rq_flags & RQF_ELVPRIV) {
1163                 if (unlikely(et->icq_cache && !icq)) {
1164                         if (ioc)
1165                                 icq = ioc_create_icq(ioc, q, gfp_mask);
1166                         if (!icq)
1167                                 goto fail_elvpriv;
1168                 }
1169 
1170                 rq->elv.icq = icq;
1171                 if (unlikely(elv_set_request(q, rq, bio, gfp_mask)))
1172                         goto fail_elvpriv;
1173 
1174                 /* @rq->elv.icq holds io_context until @rq is freed */
1175                 if (icq)
1176                         get_io_context(icq->ioc);
1177         }
1178 out:
1179         /*
1180          * ioc may be NULL here, and ioc_batching will be false. That's
1181          * OK, if the queue is under the request limit then requests need
1182          * not count toward the nr_batch_requests limit. There will always
1183          * be some limit enforced by BLK_BATCH_TIME.
1184          */
1185         if (ioc_batching(q, ioc))
1186                 ioc->nr_batch_requests--;
1187 
1188         trace_block_getrq(q, bio, op);
1189         return rq;
1190 
1191 fail_elvpriv:
1192         /*
1193          * elvpriv init failed.  ioc, icq and elvpriv aren't mempool backed
1194          * and may fail indefinitely under memory pressure and thus
1195          * shouldn't stall IO.  Treat this request as !elvpriv.  This will
1196          * disturb iosched and blkcg but weird is bettern than dead.
1197          */
1198         printk_ratelimited(KERN_WARNING "%s: dev %s: request aux data allocation failed, iosched may be disturbed\n",
1199                            __func__, dev_name(q->backing_dev_info.dev));
1200 
1201         rq->rq_flags &= ~RQF_ELVPRIV;
1202         rq->elv.icq = NULL;
1203 
1204         spin_lock_irq(q->queue_lock);
1205         q->nr_rqs_elvpriv--;
1206         spin_unlock_irq(q->queue_lock);
1207         goto out;
1208 
1209 fail_alloc:
1210         /*
1211          * Allocation failed presumably due to memory. Undo anything we
1212          * might have messed up.
1213          *
1214          * Allocating task should really be put onto the front of the wait
1215          * queue, but this is pretty rare.
1216          */
1217         spin_lock_irq(q->queue_lock);
1218         freed_request(rl, is_sync, rq_flags);
1219 
1220         /*
1221          * in the very unlikely event that allocation failed and no
1222          * requests for this direction was pending, mark us starved so that
1223          * freeing of a request in the other direction will notice
1224          * us. another possible fix would be to split the rq mempool into
1225          * READ and WRITE
1226          */
1227 rq_starved:
1228         if (unlikely(rl->count[is_sync] == 0))
1229                 rl->starved[is_sync] = 1;
1230         return ERR_PTR(-ENOMEM);
1231 }
1232 
1233 /**
1234  * get_request - get a free request
1235  * @q: request_queue to allocate request from
1236  * @op: operation and flags
1237  * @bio: bio to allocate request for (can be %NULL)
1238  * @gfp_mask: allocation mask
1239  *
1240  * Get a free request from @q.  If %__GFP_DIRECT_RECLAIM is set in @gfp_mask,
1241  * this function keeps retrying under memory pressure and fails iff @q is dead.
1242  *
1243  * Must be called with @q->queue_lock held and,
1244  * Returns ERR_PTR on failure, with @q->queue_lock held.
1245  * Returns request pointer on success, with @q->queue_lock *not held*.
1246  */
1247 static struct request *get_request(struct request_queue *q, unsigned int op,
1248                 struct bio *bio, gfp_t gfp_mask)
1249 {
1250         const bool is_sync = op_is_sync(op);
1251         DEFINE_WAIT(wait);
1252         struct request_list *rl;
1253         struct request *rq;
1254 
1255         rl = blk_get_rl(q, bio);        /* transferred to @rq on success */
1256 retry:
1257         rq = __get_request(rl, op, bio, gfp_mask);
1258         if (!IS_ERR(rq))
1259                 return rq;
1260 
1261         if (!gfpflags_allow_blocking(gfp_mask) || unlikely(blk_queue_dying(q))) {
1262                 blk_put_rl(rl);
1263                 return rq;
1264         }
1265 
1266         /* wait on @rl and retry */
1267         prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
1268                                   TASK_UNINTERRUPTIBLE);
1269 
1270         trace_block_sleeprq(q, bio, op);
1271 
1272         spin_unlock_irq(q->queue_lock);
1273         io_schedule();
1274 
1275         /*
1276          * After sleeping, we become a "batching" process and will be able
1277          * to allocate at least one request, and up to a big batch of them
1278          * for a small period time.  See ioc_batching, ioc_set_batching
1279          */
1280         ioc_set_batching(q, current->io_context);
1281 
1282         spin_lock_irq(q->queue_lock);
1283         finish_wait(&rl->wait[is_sync], &wait);
1284 
1285         goto retry;
1286 }
1287 
1288 static struct request *blk_old_get_request(struct request_queue *q, int rw,
1289                 gfp_t gfp_mask)
1290 {
1291         struct request *rq;
1292 
1293         BUG_ON(rw != READ && rw != WRITE);
1294 
1295         /* create ioc upfront */
1296         create_io_context(gfp_mask, q->node);
1297 
1298         spin_lock_irq(q->queue_lock);
1299         rq = get_request(q, rw, NULL, gfp_mask);
1300         if (IS_ERR(rq)) {
1301                 spin_unlock_irq(q->queue_lock);
1302                 return rq;
1303         }
1304 
1305         /* q->queue_lock is unlocked at this point */
1306         rq->__data_len = 0;
1307         rq->__sector = (sector_t) -1;
1308         rq->bio = rq->biotail = NULL;
1309         return rq;
1310 }
1311 
1312 struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
1313 {
1314         if (q->mq_ops)
1315                 return blk_mq_alloc_request(q, rw,
1316                         (gfp_mask & __GFP_DIRECT_RECLAIM) ?
1317                                 0 : BLK_MQ_REQ_NOWAIT);
1318         else
1319                 return blk_old_get_request(q, rw, gfp_mask);
1320 }
1321 EXPORT_SYMBOL(blk_get_request);
1322 
1323 /**
1324  * blk_rq_set_block_pc - initialize a request to type BLOCK_PC
1325  * @rq:         request to be initialized
1326  *
1327  */
1328 void blk_rq_set_block_pc(struct request *rq)
1329 {
1330         rq->cmd_type = REQ_TYPE_BLOCK_PC;
1331         memset(rq->__cmd, 0, sizeof(rq->__cmd));
1332 }
1333 EXPORT_SYMBOL(blk_rq_set_block_pc);
1334 
1335 /**
1336  * blk_requeue_request - put a request back on queue
1337  * @q:          request queue where request should be inserted
1338  * @rq:         request to be inserted
1339  *
1340  * Description:
1341  *    Drivers often keep queueing requests until the hardware cannot accept
1342  *    more, when that condition happens we need to put the request back
1343  *    on the queue. Must be called with queue lock held.
1344  */
1345 void blk_requeue_request(struct request_queue *q, struct request *rq)
1346 {
1347         blk_delete_timer(rq);
1348         blk_clear_rq_complete(rq);
1349         trace_block_rq_requeue(q, rq);
1350         wbt_requeue(q->rq_wb, &rq->issue_stat);
1351 
1352         if (rq->rq_flags & RQF_QUEUED)
1353                 blk_queue_end_tag(q, rq);
1354 
1355         BUG_ON(blk_queued_rq(rq));
1356 
1357         elv_requeue_request(q, rq);
1358 }
1359 EXPORT_SYMBOL(blk_requeue_request);
1360 
1361 static void add_acct_request(struct request_queue *q, struct request *rq,
1362                              int where)
1363 {
1364         blk_account_io_start(rq, true);
1365         __elv_add_request(q, rq, where);
1366 }
1367 
1368 static void part_round_stats_single(int cpu, struct hd_struct *part,
1369                                     unsigned long now)
1370 {
1371         int inflight;
1372 
1373         if (now == part->stamp)
1374                 return;
1375 
1376         inflight = part_in_flight(part);
1377         if (inflight) {
1378                 __part_stat_add(cpu, part, time_in_queue,
1379                                 inflight * (now - part->stamp));
1380                 __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
1381         }
1382         part->stamp = now;
1383 }
1384 
1385 /**
1386  * part_round_stats() - Round off the performance stats on a struct disk_stats.
1387  * @cpu: cpu number for stats access
1388  * @part: target partition
1389  *
1390  * The average IO queue length and utilisation statistics are maintained
1391  * by observing the current state of the queue length and the amount of
1392  * time it has been in this state for.
1393  *
1394  * Normally, that accounting is done on IO completion, but that can result
1395  * in more than a second's worth of IO being accounted for within any one
1396  * second, leading to >100% utilisation.  To deal with that, we call this
1397  * function to do a round-off before returning the results when reading
1398  * /proc/diskstats.  This accounts immediately for all queue usage up to
1399  * the current jiffies and restarts the counters again.
1400  */
1401 void part_round_stats(int cpu, struct hd_struct *part)
1402 {
1403         unsigned long now = jiffies;
1404 
1405         if (part->partno)
1406                 part_round_stats_single(cpu, &part_to_disk(part)->part0, now);
1407         part_round_stats_single(cpu, part, now);
1408 }
1409 EXPORT_SYMBOL_GPL(part_round_stats);
1410 
1411 #ifdef CONFIG_PM
1412 static void blk_pm_put_request(struct request *rq)
1413 {
1414         if (rq->q->dev && !(rq->rq_flags & RQF_PM) && !--rq->q->nr_pending)
1415                 pm_runtime_mark_last_busy(rq->q->dev);
1416 }
1417 #else
1418 static inline void blk_pm_put_request(struct request *rq) {}
1419 #endif
1420 
1421 /*
1422  * queue lock must be held
1423  */
1424 void __blk_put_request(struct request_queue *q, struct request *req)
1425 {
1426         req_flags_t rq_flags = req->rq_flags;
1427 
1428         if (unlikely(!q))
1429                 return;
1430 
1431         if (q->mq_ops) {
1432                 blk_mq_free_request(req);
1433                 return;
1434         }
1435 
1436         blk_pm_put_request(req);
1437 
1438         elv_completed_request(q, req);
1439 
1440         /* this is a bio leak */
1441         WARN_ON(req->bio != NULL);
1442 
1443         wbt_done(q->rq_wb, &req->issue_stat);
1444 
1445         /*
1446          * Request may not have originated from ll_rw_blk. if not,
1447          * it didn't come out of our reserved rq pools
1448          */
1449         if (rq_flags & RQF_ALLOCED) {
1450                 struct request_list *rl = blk_rq_rl(req);
1451                 bool sync = op_is_sync(req->cmd_flags);
1452 
1453                 BUG_ON(!list_empty(&req->queuelist));
1454                 BUG_ON(ELV_ON_HASH(req));
1455 
1456                 blk_free_request(rl, req);
1457                 freed_request(rl, sync, rq_flags);
1458                 blk_put_rl(rl);
1459         }
1460 }
1461 EXPORT_SYMBOL_GPL(__blk_put_request);
1462 
1463 void blk_put_request(struct request *req)
1464 {
1465         struct request_queue *q = req->q;
1466 
1467         if (q->mq_ops)
1468                 blk_mq_free_request(req);
1469         else {
1470                 unsigned long flags;
1471 
1472                 spin_lock_irqsave(q->queue_lock, flags);
1473                 __blk_put_request(q, req);
1474                 spin_unlock_irqrestore(q->queue_lock, flags);
1475         }
1476 }
1477 EXPORT_SYMBOL(blk_put_request);
1478 
1479 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
1480                             struct bio *bio)
1481 {
1482         const int ff = bio->bi_opf & REQ_FAILFAST_MASK;
1483 
1484         if (!ll_back_merge_fn(q, req, bio))
1485                 return false;
1486 
1487         trace_block_bio_backmerge(q, req, bio);
1488 
1489         if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1490                 blk_rq_set_mixed_merge(req);
1491 
1492         req->biotail->bi_next = bio;
1493         req->biotail = bio;
1494         req->__data_len += bio->bi_iter.bi_size;
1495         req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1496 
1497         blk_account_io_start(req, false);
1498         return true;
1499 }
1500 
1501 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
1502                              struct bio *bio)
1503 {
1504         const int ff = bio->bi_opf & REQ_FAILFAST_MASK;
1505 
1506         if (!ll_front_merge_fn(q, req, bio))
1507                 return false;
1508 
1509         trace_block_bio_frontmerge(q, req, bio);
1510 
1511         if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1512                 blk_rq_set_mixed_merge(req);
1513 
1514         bio->bi_next = req->bio;
1515         req->bio = bio;
1516 
1517         req->__sector = bio->bi_iter.bi_sector;
1518         req->__data_len += bio->bi_iter.bi_size;
1519         req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1520 
1521         blk_account_io_start(req, false);
1522         return true;
1523 }
1524 
1525 /**
1526  * blk_attempt_plug_merge - try to merge with %current's plugged list
1527  * @q: request_queue new bio is being queued at
1528  * @bio: new bio being queued
1529  * @request_count: out parameter for number of traversed plugged requests
1530  * @same_queue_rq: pointer to &struct request that gets filled in when
1531  * another request associated with @q is found on the plug list
1532  * (optional, may be %NULL)
1533  *
1534  * Determine whether @bio being queued on @q can be merged with a request
1535  * on %current's plugged list.  Returns %true if merge was successful,
1536  * otherwise %false.
1537  *
1538  * Plugging coalesces IOs from the same issuer for the same purpose without
1539  * going through @q->queue_lock.  As such it's more of an issuing mechanism
1540  * than scheduling, and the request, while may have elvpriv data, is not
1541  * added on the elevator at this point.  In addition, we don't have
1542  * reliable access to the elevator outside queue lock.  Only check basic
1543  * merging parameters without querying the elevator.
1544  *
1545  * Caller must ensure !blk_queue_nomerges(q) beforehand.
1546  */
1547 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
1548                             unsigned int *request_count,
1549                             struct request **same_queue_rq)
1550 {
1551         struct blk_plug *plug;
1552         struct request *rq;
1553         bool ret = false;
1554         struct list_head *plug_list;
1555 
1556         plug = current->plug;
1557         if (!plug)
1558                 goto out;
1559         *request_count = 0;
1560 
1561         if (q->mq_ops)
1562                 plug_list = &plug->mq_list;
1563         else
1564                 plug_list = &plug->list;
1565 
1566         list_for_each_entry_reverse(rq, plug_list, queuelist) {
1567                 int el_ret;
1568 
1569                 if (rq->q == q) {
1570                         (*request_count)++;
1571                         /*
1572                          * Only blk-mq multiple hardware queues case checks the
1573                          * rq in the same queue, there should be only one such
1574                          * rq in a queue
1575                          **/
1576                         if (same_queue_rq)
1577                                 *same_queue_rq = rq;
1578                 }
1579 
1580                 if (rq->q != q || !blk_rq_merge_ok(rq, bio))
1581                         continue;
1582 
1583                 el_ret = blk_try_merge(rq, bio);
1584                 if (el_ret == ELEVATOR_BACK_MERGE) {
1585                         ret = bio_attempt_back_merge(q, rq, bio);
1586                         if (ret)
1587                                 break;
1588                 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
1589                         ret = bio_attempt_front_merge(q, rq, bio);
1590                         if (ret)
1591                                 break;
1592                 }
1593         }
1594 out:
1595         return ret;
1596 }
1597 
1598 unsigned int blk_plug_queued_count(struct request_queue *q)
1599 {
1600         struct blk_plug *plug;
1601         struct request *rq;
1602         struct list_head *plug_list;
1603         unsigned int ret = 0;
1604 
1605         plug = current->plug;
1606         if (!plug)
1607                 goto out;
1608 
1609         if (q->mq_ops)
1610                 plug_list = &plug->mq_list;
1611         else
1612                 plug_list = &plug->list;
1613 
1614         list_for_each_entry(rq, plug_list, queuelist) {
1615                 if (rq->q == q)
1616                         ret++;
1617         }
1618 out:
1619         return ret;
1620 }
1621 
1622 void init_request_from_bio(struct request *req, struct bio *bio)
1623 {
1624         req->cmd_type = REQ_TYPE_FS;
1625         if (bio->bi_opf & REQ_RAHEAD)
1626                 req->cmd_flags |= REQ_FAILFAST_MASK;
1627 
1628         req->errors = 0;
1629         req->__sector = bio->bi_iter.bi_sector;
1630         if (ioprio_valid(bio_prio(bio)))
1631                 req->ioprio = bio_prio(bio);
1632         blk_rq_bio_prep(req->q, req, bio);
1633 }
1634 
1635 static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
1636 {
1637         struct blk_plug *plug;
1638         int el_ret, where = ELEVATOR_INSERT_SORT;
1639         struct request *req;
1640         unsigned int request_count = 0;
1641         unsigned int wb_acct;
1642 
1643         /*
1644          * low level driver can indicate that it wants pages above a
1645          * certain limit bounced to low memory (ie for highmem, or even
1646          * ISA dma in theory)
1647          */
1648         blk_queue_bounce(q, &bio);
1649 
1650         blk_queue_split(q, &bio, q->bio_split);
1651 
1652         if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1653                 bio->bi_error = -EIO;
1654                 bio_endio(bio);
1655                 return BLK_QC_T_NONE;
1656         }
1657 
1658         if (bio->bi_opf & (REQ_PREFLUSH | REQ_FUA)) {
1659                 spin_lock_irq(q->queue_lock);
1660                 where = ELEVATOR_INSERT_FLUSH;
1661                 goto get_rq;
1662         }
1663 
1664         /*
1665          * Check if we can merge with the plugged list before grabbing
1666          * any locks.
1667          */
1668         if (!blk_queue_nomerges(q)) {
1669                 if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
1670                         return BLK_QC_T_NONE;
1671         } else
1672                 request_count = blk_plug_queued_count(q);
1673 
1674         spin_lock_irq(q->queue_lock);
1675 
1676         el_ret = elv_merge(q, &req, bio);
1677         if (el_ret == ELEVATOR_BACK_MERGE) {
1678                 if (bio_attempt_back_merge(q, req, bio)) {
1679                         elv_bio_merged(q, req, bio);
1680                         if (!attempt_back_merge(q, req))
1681                                 elv_merged_request(q, req, el_ret);
1682                         goto out_unlock;
1683                 }
1684         } else if (el_ret == ELEVATOR_FRONT_MERGE) {
1685                 if (bio_attempt_front_merge(q, req, bio)) {
1686                         elv_bio_merged(q, req, bio);
1687                         if (!attempt_front_merge(q, req))
1688                                 elv_merged_request(q, req, el_ret);
1689                         goto out_unlock;
1690                 }
1691         }
1692 
1693 get_rq:
1694         wb_acct = wbt_wait(q->rq_wb, bio, q->queue_lock);
1695 
1696         /*
1697          * Grab a free request. This is might sleep but can not fail.
1698          * Returns with the queue unlocked.
1699          */
1700         req = get_request(q, bio->bi_opf, bio, GFP_NOIO);
1701         if (IS_ERR(req)) {
1702                 __wbt_done(q->rq_wb, wb_acct);
1703                 bio->bi_error = PTR_ERR(req);
1704                 bio_endio(bio);
1705                 goto out_unlock;
1706         }
1707 
1708         wbt_track(&req->issue_stat, wb_acct);
1709 
1710         /*
1711          * After dropping the lock and possibly sleeping here, our request
1712          * may now be mergeable after it had proven unmergeable (above).
1713          * We don't worry about that case for efficiency. It won't happen
1714          * often, and the elevators are able to handle it.
1715          */
1716         init_request_from_bio(req, bio);
1717 
1718         if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags))
1719                 req->cpu = raw_smp_processor_id();
1720 
1721         plug = current->plug;
1722         if (plug) {
1723                 /*
1724                  * If this is the first request added after a plug, fire
1725                  * of a plug trace.
1726                  *
1727                  * @request_count may become stale because of schedule
1728                  * out, so check plug list again.
1729                  */
1730                 if (!request_count || list_empty(&plug->list))
1731                         trace_block_plug(q);
1732                 else {
1733                         struct request *last = list_entry_rq(plug->list.prev);
1734                         if (request_count >= BLK_MAX_REQUEST_COUNT ||
1735                             blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE) {
1736                                 blk_flush_plug_list(plug, false);
1737                                 trace_block_plug(q);
1738                         }
1739                 }
1740                 list_add_tail(&req->queuelist, &plug->list);
1741                 blk_account_io_start(req, true);
1742         } else {
1743                 spin_lock_irq(q->queue_lock);
1744                 add_acct_request(q, req, where);
1745                 __blk_run_queue(q);
1746 out_unlock:
1747                 spin_unlock_irq(q->queue_lock);
1748         }
1749 
1750         return BLK_QC_T_NONE;
1751 }
1752 
1753 /*
1754  * If bio->bi_dev is a partition, remap the location
1755  */
1756 static inline void blk_partition_remap(struct bio *bio)
1757 {
1758         struct block_device *bdev = bio->bi_bdev;
1759 
1760         /*
1761          * Zone reset does not include bi_size so bio_sectors() is always 0.
1762          * Include a test for the reset op code and perform the remap if needed.
1763          */
1764         if (bdev != bdev->bd_contains &&
1765             (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET)) {
1766                 struct hd_struct *p = bdev->bd_part;
1767 
1768                 bio->bi_iter.bi_sector += p->start_sect;
1769                 bio->bi_bdev = bdev->bd_contains;
1770 
1771                 trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), bio,
1772                                       bdev->bd_dev,
1773                                       bio->bi_iter.bi_sector - p->start_sect);
1774         }
1775 }
1776 
1777 static void handle_bad_sector(struct bio *bio)
1778 {
1779         char b[BDEVNAME_SIZE];
1780 
1781         printk(KERN_INFO "attempt to access beyond end of device\n");
1782         printk(KERN_INFO "%s: rw=%d, want=%Lu, limit=%Lu\n",
1783                         bdevname(bio->bi_bdev, b),
1784                         bio->bi_opf,
1785                         (unsigned long long)bio_end_sector(bio),
1786                         (long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9));
1787 }
1788 
1789 #ifdef CONFIG_FAIL_MAKE_REQUEST
1790 
1791 static DECLARE_FAULT_ATTR(fail_make_request);
1792 
1793 static int __init setup_fail_make_request(char *str)
1794 {
1795         return setup_fault_attr(&fail_make_request, str);
1796 }
1797 __setup("fail_make_request=", setup_fail_make_request);
1798 
1799 static bool should_fail_request(struct hd_struct *part, unsigned int bytes)
1800 {
1801         return part->make_it_fail && should_fail(&fail_make_request, bytes);
1802 }
1803 
1804 static int __init fail_make_request_debugfs(void)
1805 {
1806         struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
1807                                                 NULL, &fail_make_request);
1808 
1809         return PTR_ERR_OR_ZERO(dir);
1810 }
1811 
1812 late_initcall(fail_make_request_debugfs);
1813 
1814 #else /* CONFIG_FAIL_MAKE_REQUEST */
1815 
1816 static inline bool should_fail_request(struct hd_struct *part,
1817                                         unsigned int bytes)
1818 {
1819         return false;
1820 }
1821 
1822 #endif /* CONFIG_FAIL_MAKE_REQUEST */
1823 
1824 /*
1825  * Check whether this bio extends beyond the end of the device.
1826  */
1827 static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
1828 {
1829         sector_t maxsector;
1830 
1831         if (!nr_sectors)
1832                 return 0;
1833 
1834         /* Test device or partition size, when known. */
1835         maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9;
1836         if (maxsector) {
1837                 sector_t sector = bio->bi_iter.bi_sector;
1838 
1839                 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
1840                         /*
1841                          * This may well happen - the kernel calls bread()
1842                          * without checking the size of the device, e.g., when
1843                          * mounting a device.
1844                          */
1845                         handle_bad_sector(bio);
1846                         return 1;
1847                 }
1848         }
1849 
1850         return 0;
1851 }
1852 
1853 static noinline_for_stack bool
1854 generic_make_request_checks(struct bio *bio)
1855 {
1856         struct request_queue *q;
1857         int nr_sectors = bio_sectors(bio);
1858         int err = -EIO;
1859         char b[BDEVNAME_SIZE];
1860         struct hd_struct *part;
1861 
1862         might_sleep();
1863 
1864         if (bio_check_eod(bio, nr_sectors))
1865                 goto end_io;
1866 
1867         q = bdev_get_queue(bio->bi_bdev);
1868         if (unlikely(!q)) {
1869                 printk(KERN_ERR
1870                        "generic_make_request: Trying to access "
1871                         "nonexistent block-device %s (%Lu)\n",
1872                         bdevname(bio->bi_bdev, b),
1873                         (long long) bio->bi_iter.bi_sector);
1874                 goto end_io;
1875         }
1876 
1877         part = bio->bi_bdev->bd_part;
1878         if (should_fail_request(part, bio->bi_iter.bi_size) ||
1879             should_fail_request(&part_to_disk(part)->part0,
1880                                 bio->bi_iter.bi_size))
1881                 goto end_io;
1882 
1883         /*
1884          * If this device has partitions, remap block n
1885          * of partition p to block n+start(p) of the disk.
1886          */
1887         blk_partition_remap(bio);
1888 
1889         if (bio_check_eod(bio, nr_sectors))
1890                 goto end_io;
1891 
1892         /*
1893          * Filter flush bio's early so that make_request based
1894          * drivers without flush support don't have to worry
1895          * about them.
1896          */
1897         if ((bio->bi_opf & (REQ_PREFLUSH | REQ_FUA)) &&
1898             !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) {
1899                 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA);
1900                 if (!nr_sectors) {
1901                         err = 0;
1902                         goto end_io;
1903                 }
1904         }
1905 
1906         switch (bio_op(bio)) {
1907         case REQ_OP_DISCARD:
1908                 if (!blk_queue_discard(q))
1909                         goto not_supported;
1910                 break;
1911         case REQ_OP_SECURE_ERASE:
1912                 if (!blk_queue_secure_erase(q))
1913                         goto not_supported;
1914                 break;
1915         case REQ_OP_WRITE_SAME:
1916                 if (!bdev_write_same(bio->bi_bdev))
1917                         goto not_supported;
1918                 break;
1919         case REQ_OP_ZONE_REPORT:
1920         case REQ_OP_ZONE_RESET:
1921                 if (!bdev_is_zoned(bio->bi_bdev))
1922                         goto not_supported;
1923                 break;
1924         case REQ_OP_WRITE_ZEROES:
1925                 if (!bdev_write_zeroes_sectors(bio->bi_bdev))
1926                         goto not_supported;
1927                 break;
1928         default:
1929                 break;
1930         }
1931 
1932         /*
1933          * Various block parts want %current->io_context and lazy ioc
1934          * allocation ends up trading a lot of pain for a small amount of
1935          * memory.  Just allocate it upfront.  This may fail and block
1936          * layer knows how to live with it.
1937          */
1938         create_io_context(GFP_ATOMIC, q->node);
1939 
1940         if (!blkcg_bio_issue_check(q, bio))
1941                 return false;
1942 
1943         trace_block_bio_queue(q, bio);
1944         return true;
1945 
1946 not_supported:
1947         err = -EOPNOTSUPP;
1948 end_io:
1949         bio->bi_error = err;
1950         bio_endio(bio);
1951         return false;
1952 }
1953 
1954 /**
1955  * generic_make_request - hand a buffer to its device driver for I/O
1956  * @bio:  The bio describing the location in memory and on the device.
1957  *
1958  * generic_make_request() is used to make I/O requests of block
1959  * devices. It is passed a &struct bio, which describes the I/O that needs
1960  * to be done.
1961  *
1962  * generic_make_request() does not return any status.  The
1963  * success/failure status of the request, along with notification of
1964  * completion, is delivered asynchronously through the bio->bi_end_io
1965  * function described (one day) else where.
1966  *
1967  * The caller of generic_make_request must make sure that bi_io_vec
1968  * are set to describe the memory buffer, and that bi_dev and bi_sector are
1969  * set to describe the device address, and the
1970  * bi_end_io and optionally bi_private are set to describe how
1971  * completion notification should be signaled.
1972  *
1973  * generic_make_request and the drivers it calls may use bi_next if this
1974  * bio happens to be merged with someone else, and may resubmit the bio to
1975  * a lower device by calling into generic_make_request recursively, which
1976  * means the bio should NOT be touched after the call to ->make_request_fn.
1977  */
1978 blk_qc_t generic_make_request(struct bio *bio)
1979 {
1980         struct bio_list bio_list_on_stack;
1981         blk_qc_t ret = BLK_QC_T_NONE;
1982 
1983         if (!generic_make_request_checks(bio))
1984                 goto out;
1985 
1986         /*
1987          * We only want one ->make_request_fn to be active at a time, else
1988          * stack usage with stacked devices could be a problem.  So use
1989          * current->bio_list to keep a list of requests submited by a
1990          * make_request_fn function.  current->bio_list is also used as a
1991          * flag to say if generic_make_request is currently active in this
1992          * task or not.  If it is NULL, then no make_request is active.  If
1993          * it is non-NULL, then a make_request is active, and new requests
1994          * should be added at the tail
1995          */
1996         if (current->bio_list) {
1997                 bio_list_add(current->bio_list, bio);
1998                 goto out;
1999         }
2000 
2001         /* following loop may be a bit non-obvious, and so deserves some
2002          * explanation.
2003          * Before entering the loop, bio->bi_next is NULL (as all callers
2004          * ensure that) so we have a list with a single bio.
2005          * We pretend that we have just taken it off a longer list, so
2006          * we assign bio_list to a pointer to the bio_list_on_stack,
2007          * thus initialising the bio_list of new bios to be
2008          * added.  ->make_request() may indeed add some more bios
2009          * through a recursive call to generic_make_request.  If it
2010          * did, we find a non-NULL value in bio_list and re-enter the loop
2011          * from the top.  In this case we really did just take the bio
2012          * of the top of the list (no pretending) and so remove it from
2013          * bio_list, and call into ->make_request() again.
2014          */
2015         BUG_ON(bio->bi_next);
2016         bio_list_init(&bio_list_on_stack);
2017         current->bio_list = &bio_list_on_stack;
2018         do {
2019                 struct request_queue *q = bdev_get_queue(bio->bi_bdev);
2020 
2021                 if (likely(blk_queue_enter(q, false) == 0)) {
2022                         ret = q->make_request_fn(q, bio);
2023 
2024                         blk_queue_exit(q);
2025 
2026                         bio = bio_list_pop(current->bio_list);
2027                 } else {
2028                         struct bio *bio_next = bio_list_pop(current->bio_list);
2029 
2030                         bio_io_error(bio);
2031                         bio = bio_next;
2032                 }
2033         } while (bio);
2034         current->bio_list = NULL; /* deactivate */
2035 
2036 out:
2037         return ret;
2038 }
2039 EXPORT_SYMBOL(generic_make_request);
2040 
2041 /**
2042  * submit_bio - submit a bio to the block device layer for I/O
2043  * @bio: The &struct bio which describes the I/O
2044  *
2045  * submit_bio() is very similar in purpose to generic_make_request(), and
2046  * uses that function to do most of the work. Both are fairly rough
2047  * interfaces; @bio must be presetup and ready for I/O.
2048  *
2049  */
2050 blk_qc_t submit_bio(struct bio *bio)
2051 {
2052         /*
2053          * If it's a regular read/write or a barrier with data attached,
2054          * go through the normal accounting stuff before submission.
2055          */
2056         if (bio_has_data(bio)) {
2057                 unsigned int count;
2058 
2059                 if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME))
2060                         count = bdev_logical_block_size(bio->bi_bdev) >> 9;
2061                 else
2062                         count = bio_sectors(bio);
2063 
2064                 if (op_is_write(bio_op(bio))) {
2065                         count_vm_events(PGPGOUT, count);
2066                 } else {
2067                         task_io_account_read(bio->bi_iter.bi_size);
2068                         count_vm_events(PGPGIN, count);
2069                 }
2070 
2071                 if (unlikely(block_dump)) {
2072                         char b[BDEVNAME_SIZE];
2073                         printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n",
2074                         current->comm, task_pid_nr(current),
2075                                 op_is_write(bio_op(bio)) ? "WRITE" : "READ",
2076                                 (unsigned long long)bio->bi_iter.bi_sector,
2077                                 bdevname(bio->bi_bdev, b),
2078                                 count);
2079                 }
2080         }
2081 
2082         return generic_make_request(bio);
2083 }
2084 EXPORT_SYMBOL(submit_bio);
2085 
2086 /**
2087  * blk_cloned_rq_check_limits - Helper function to check a cloned request
2088  *                              for new the queue limits
2089  * @q:  the queue
2090  * @rq: the request being checked
2091  *
2092  * Description:
2093  *    @rq may have been made based on weaker limitations of upper-level queues
2094  *    in request stacking drivers, and it may violate the limitation of @q.
2095  *    Since the block layer and the underlying device driver trust @rq
2096  *    after it is inserted to @q, it should be checked against @q before
2097  *    the insertion using this generic function.
2098  *
2099  *    Request stacking drivers like request-based dm may change the queue
2100  *    limits when retrying requests on other queues. Those requests need
2101  *    to be checked against the new queue limits again during dispatch.
2102  */
2103 static int blk_cloned_rq_check_limits(struct request_queue *q,
2104                                       struct request *rq)
2105 {
2106         if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, req_op(rq))) {
2107                 printk(KERN_ERR "%s: over max size limit.\n", __func__);
2108                 return -EIO;
2109         }
2110 
2111         /*
2112          * queue's settings related to segment counting like q->bounce_pfn
2113          * may differ from that of other stacking queues.
2114          * Recalculate it to check the request correctly on this queue's
2115          * limitation.
2116          */
2117         blk_recalc_rq_segments(rq);
2118         if (rq->nr_phys_segments > queue_max_segments(q)) {
2119                 printk(KERN_ERR "%s: over max segments limit.\n", __func__);
2120                 return -EIO;
2121         }
2122 
2123         return 0;
2124 }
2125 
2126 /**
2127  * blk_insert_cloned_request - Helper for stacking drivers to submit a request
2128  * @q:  the queue to submit the request
2129  * @rq: the request being queued
2130  */
2131 int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
2132 {
2133         unsigned long flags;
2134         int where = ELEVATOR_INSERT_BACK;
2135 
2136         if (blk_cloned_rq_check_limits(q, rq))
2137                 return -EIO;
2138 
2139         if (rq->rq_disk &&
2140             should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
2141                 return -EIO;
2142 
2143         if (q->mq_ops) {
2144                 if (blk_queue_io_stat(q))
2145                         blk_account_io_start(rq, true);
2146                 blk_mq_insert_request(rq, false, true, false);
2147                 return 0;
2148         }
2149 
2150         spin_lock_irqsave(q->queue_lock, flags);
2151         if (unlikely(blk_queue_dying(q))) {
2152                 spin_unlock_irqrestore(q->queue_lock, flags);
2153                 return -ENODEV;
2154         }
2155 
2156         /*
2157          * Submitting request must be dequeued before calling this function
2158          * because it will be linked to another request_queue
2159          */
2160         BUG_ON(blk_queued_rq(rq));
2161 
2162         if (rq->cmd_flags & (REQ_PREFLUSH | REQ_FUA))
2163                 where = ELEVATOR_INSERT_FLUSH;
2164 
2165         add_acct_request(q, rq, where);
2166         if (where == ELEVATOR_INSERT_FLUSH)
2167                 __blk_run_queue(q);
2168         spin_unlock_irqrestore(q->queue_lock, flags);
2169 
2170         return 0;
2171 }
2172 EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
2173 
2174 /**
2175  * blk_rq_err_bytes - determine number of bytes till the next failure boundary
2176  * @rq: request to examine
2177  *
2178  * Description:
2179  *     A request could be merge of IOs which require different failure
2180  *     handling.  This function determines the number of bytes which
2181  *     can be failed from the beginning of the request without
2182  *     crossing into area which need to be retried further.
2183  *
2184  * Return:
2185  *     The number of bytes to fail.
2186  *
2187  * Context:
2188  *     queue_lock must be held.
2189  */
2190 unsigned int blk_rq_err_bytes(const struct request *rq)
2191 {
2192         unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
2193         unsigned int bytes = 0;
2194         struct bio *bio;
2195 
2196         if (!(rq->rq_flags & RQF_MIXED_MERGE))
2197                 return blk_rq_bytes(rq);
2198 
2199         /*
2200          * Currently the only 'mixing' which can happen is between
2201          * different fastfail types.  We can safely fail portions
2202          * which have all the failfast bits that the first one has -
2203          * the ones which are at least as eager to fail as the first
2204          * one.
2205          */
2206         for (bio = rq->bio; bio; bio = bio->bi_next) {
2207                 if ((bio->bi_opf & ff) != ff)
2208                         break;
2209                 bytes += bio->bi_iter.bi_size;
2210         }
2211 
2212         /* this could lead to infinite loop */
2213         BUG_ON(blk_rq_bytes(rq) && !bytes);
2214         return bytes;
2215 }
2216 EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
2217 
2218 void blk_account_io_completion(struct request *req, unsigned int bytes)
2219 {
2220         if (blk_do_io_stat(req)) {
2221                 const int rw = rq_data_dir(req);
2222                 struct hd_struct *part;
2223                 int cpu;
2224 
2225                 cpu = part_stat_lock();
2226                 part = req->part;
2227                 part_stat_add(cpu, part, sectors[rw], bytes >> 9);
2228                 part_stat_unlock();
2229         }
2230 }
2231 
2232 void blk_account_io_done(struct request *req)
2233 {
2234         /*
2235          * Account IO completion.  flush_rq isn't accounted as a
2236          * normal IO on queueing nor completion.  Accounting the
2237          * containing request is enough.
2238          */
2239         if (blk_do_io_stat(req) && !(req->rq_flags & RQF_FLUSH_SEQ)) {
2240                 unsigned long duration = jiffies - req->start_time;
2241                 const int rw = rq_data_dir(req);
2242                 struct hd_struct *part;
2243                 int cpu;
2244 
2245                 cpu = part_stat_lock();
2246                 part = req->part;
2247 
2248                 part_stat_inc(cpu, part, ios[rw]);
2249                 part_stat_add(cpu, part, ticks[rw], duration);
2250                 part_round_stats(cpu, part);
2251                 part_dec_in_flight(part, rw);
2252 
2253                 hd_struct_put(part);
2254                 part_stat_unlock();
2255         }
2256 }
2257 
2258 #ifdef CONFIG_PM
2259 /*
2260  * Don't process normal requests when queue is suspended
2261  * or in the process of suspending/resuming
2262  */
2263 static struct request *blk_pm_peek_request(struct request_queue *q,
2264                                            struct request *rq)
2265 {
2266         if (q->dev && (q->rpm_status == RPM_SUSPENDED ||
2267             (q->rpm_status != RPM_ACTIVE && !(rq->rq_flags & RQF_PM))))
2268                 return NULL;
2269         else
2270                 return rq;
2271 }
2272 #else
2273 static inline struct request *blk_pm_peek_request(struct request_queue *q,
2274                                                   struct request *rq)
2275 {
2276         return rq;
2277 }
2278 #endif
2279 
2280 void blk_account_io_start(struct request *rq, bool new_io)
2281 {
2282         struct hd_struct *part;
2283         int rw = rq_data_dir(rq);
2284         int cpu;
2285 
2286         if (!blk_do_io_stat(rq))
2287                 return;
2288 
2289         cpu = part_stat_lock();
2290 
2291         if (!new_io) {
2292                 part = rq->part;
2293                 part_stat_inc(cpu, part, merges[rw]);
2294         } else {
2295                 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
2296                 if (!hd_struct_try_get(part)) {
2297                         /*
2298                          * The partition is already being removed,
2299                          * the request will be accounted on the disk only
2300                          *
2301                          * We take a reference on disk->part0 although that
2302                          * partition will never be deleted, so we can treat
2303                          * it as any other partition.
2304                          */
2305                         part = &rq->rq_disk->part0;
2306                         hd_struct_get(part);
2307                 }
2308                 part_round_stats(cpu, part);
2309                 part_inc_in_flight(part, rw);
2310                 rq->part = part;
2311         }
2312 
2313         part_stat_unlock();
2314 }
2315 
2316 /**
2317  * blk_peek_request - peek at the top of a request queue
2318  * @q: request queue to peek at
2319  *
2320  * Description:
2321  *     Return the request at the top of @q.  The returned request
2322  *     should be started using blk_start_request() before LLD starts
2323  *     processing it.
2324  *
2325  * Return:
2326  *     Pointer to the request at the top of @q if available.  Null
2327  *     otherwise.
2328  *
2329  * Context:
2330  *     queue_lock must be held.
2331  */
2332 struct request *blk_peek_request(struct request_queue *q)
2333 {
2334         struct request *rq;
2335         int ret;
2336 
2337         while ((rq = __elv_next_request(q)) != NULL) {
2338 
2339                 rq = blk_pm_peek_request(q, rq);
2340                 if (!rq)
2341                         break;
2342 
2343                 if (!(rq->rq_flags & RQF_STARTED)) {
2344                         /*
2345                          * This is the first time the device driver
2346                          * sees this request (possibly after
2347                          * requeueing).  Notify IO scheduler.
2348                          */
2349                         if (rq->rq_flags & RQF_SORTED)
2350                                 elv_activate_rq(q, rq);
2351 
2352                         /*
2353                          * just mark as started even if we don't start
2354                          * it, a request that has been delayed should
2355                          * not be passed by new incoming requests
2356                          */
2357                         rq->rq_flags |= RQF_STARTED;
2358                         trace_block_rq_issue(q, rq);
2359                 }
2360 
2361                 if (!q->boundary_rq || q->boundary_rq == rq) {
2362                         q->end_sector = rq_end_sector(rq);
2363                         q->boundary_rq = NULL;
2364                 }
2365 
2366                 if (rq->rq_flags & RQF_DONTPREP)
2367                         break;
2368 
2369                 if (q->dma_drain_size && blk_rq_bytes(rq)) {
2370                         /*
2371                          * make sure space for the drain appears we
2372                          * know we can do this because max_hw_segments
2373                          * has been adjusted to be one fewer than the
2374                          * device can handle
2375                          */
2376                         rq->nr_phys_segments++;
2377                 }
2378 
2379                 if (!q->prep_rq_fn)
2380                         break;
2381 
2382                 ret = q->prep_rq_fn(q, rq);
2383                 if (ret == BLKPREP_OK) {
2384                         break;
2385                 } else if (ret == BLKPREP_DEFER) {
2386                         /*
2387                          * the request may have been (partially) prepped.
2388                          * we need to keep this request in the front to
2389                          * avoid resource deadlock.  RQF_STARTED will
2390                          * prevent other fs requests from passing this one.
2391                          */
2392                         if (q->dma_drain_size && blk_rq_bytes(rq) &&
2393                             !(rq->rq_flags & RQF_DONTPREP)) {
2394                                 /*
2395                                  * remove the space for the drain we added
2396                                  * so that we don't add it again
2397                                  */
2398                                 --rq->nr_phys_segments;
2399                         }
2400 
2401                         rq = NULL;
2402                         break;
2403                 } else if (ret == BLKPREP_KILL || ret == BLKPREP_INVALID) {
2404                         int err = (ret == BLKPREP_INVALID) ? -EREMOTEIO : -EIO;
2405 
2406                         rq->rq_flags |= RQF_QUIET;
2407                         /*
2408                          * Mark this request as started so we don't trigger
2409                          * any debug logic in the end I/O path.
2410                          */
2411                         blk_start_request(rq);
2412                         __blk_end_request_all(rq, err);
2413                 } else {
2414                         printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
2415                         break;
2416                 }
2417         }
2418 
2419         return rq;
2420 }
2421 EXPORT_SYMBOL(blk_peek_request);
2422 
2423 void blk_dequeue_request(struct request *rq)
2424 {
2425         struct request_queue *q = rq->q;
2426 
2427         BUG_ON(list_empty(&rq->queuelist));
2428         BUG_ON(ELV_ON_HASH(rq));
2429 
2430         list_del_init(&rq->queuelist);
2431 
2432         /*
2433          * the time frame between a request being removed from the lists
2434          * and to it is freed is accounted as io that is in progress at
2435          * the driver side.
2436          */
2437         if (blk_account_rq(rq)) {
2438                 q->in_flight[rq_is_sync(rq)]++;
2439                 set_io_start_time_ns(rq);
2440         }
2441 }
2442 
2443 /**
2444  * blk_start_request - start request processing on the driver
2445  * @req: request to dequeue
2446  *
2447  * Description:
2448  *     Dequeue @req and start timeout timer on it.  This hands off the
2449  *     request to the driver.
2450  *
2451  *     Block internal functions which don't want to start timer should
2452  *     call blk_dequeue_request().
2453  *
2454  * Context:
2455  *     queue_lock must be held.
2456  */
2457 void blk_start_request(struct request *req)
2458 {
2459         blk_dequeue_request(req);
2460 
2461         if (test_bit(QUEUE_FLAG_STATS, &req->q->queue_flags)) {
2462                 blk_stat_set_issue_time(&req->issue_stat);
2463                 req->rq_flags |= RQF_STATS;
2464                 wbt_issue(req->q->rq_wb, &req->issue_stat);
2465         }
2466 
2467         /*
2468          * We are now handing the request to the hardware, initialize
2469          * resid_len to full count and add the timeout handler.
2470          */
2471         req->resid_len = blk_rq_bytes(req);
2472         if (unlikely(blk_bidi_rq(req)))
2473                 req->next_rq->resid_len = blk_rq_bytes(req->next_rq);
2474 
2475         BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
2476         blk_add_timer(req);
2477 }
2478 EXPORT_SYMBOL(blk_start_request);
2479 
2480 /**
2481  * blk_fetch_request - fetch a request from a request queue
2482  * @q: request queue to fetch a request from
2483  *
2484  * Description:
2485  *     Return the request at the top of @q.  The request is started on
2486  *     return and LLD can start processing it immediately.
2487  *
2488  * Return:
2489  *     Pointer to the request at the top of @q if available.  Null
2490  *     otherwise.
2491  *
2492  * Context:
2493  *     queue_lock must be held.
2494  */
2495 struct request *blk_fetch_request(struct request_queue *q)
2496 {
2497         struct request *rq;
2498 
2499         rq = blk_peek_request(q);
2500         if (rq)
2501                 blk_start_request(rq);
2502         return rq;
2503 }
2504 EXPORT_SYMBOL(blk_fetch_request);
2505 
2506 /**
2507  * blk_update_request - Special helper function for request stacking drivers
2508  * @req:      the request being processed
2509  * @error:    %0 for success, < %0 for error
2510  * @nr_bytes: number of bytes to complete @req
2511  *
2512  * Description:
2513  *     Ends I/O on a number of bytes attached to @req, but doesn't complete
2514  *     the request structure even if @req doesn't have leftover.
2515  *     If @req has leftover, sets it up for the next range of segments.
2516  *
2517  *     This special helper function is only for request stacking drivers
2518  *     (e.g. request-based dm) so that they can handle partial completion.
2519  *     Actual device drivers should use blk_end_request instead.
2520  *
2521  *     Passing the result of blk_rq_bytes() as @nr_bytes guarantees
2522  *     %false return from this function.
2523  *
2524  * Return:
2525  *     %false - this request doesn't have any more data
2526  *     %true  - this request has more data
2527  **/
2528 bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
2529 {
2530         int total_bytes;
2531 
2532         trace_block_rq_complete(req->q, req, nr_bytes);
2533 
2534         if (!req->bio)
2535                 return false;
2536 
2537         /*
2538          * For fs requests, rq is just carrier of independent bio's
2539          * and each partial completion should be handled separately.
2540          * Reset per-request error on each partial completion.
2541          *
2542          * TODO: tj: This is too subtle.  It would be better to let
2543          * low level drivers do what they see fit.
2544          */
2545         if (req->cmd_type == REQ_TYPE_FS)
2546                 req->errors = 0;
2547 
2548         if (error && req->cmd_type == REQ_TYPE_FS &&
2549             !(req->rq_flags & RQF_QUIET)) {
2550                 char *error_type;
2551 
2552                 switch (error) {
2553                 case -ENOLINK:
2554                         error_type = "recoverable transport";
2555                         break;
2556                 case -EREMOTEIO:
2557                         error_type = "critical target";
2558                         break;
2559                 case -EBADE:
2560                         error_type = "critical nexus";
2561                         break;
2562                 case -ETIMEDOUT:
2563                         error_type = "timeout";
2564                         break;
2565                 case -ENOSPC:
2566                         error_type = "critical space allocation";
2567                         break;
2568                 case -ENODATA:
2569                         error_type = "critical medium";
2570                         break;
2571                 case -EIO:
2572                 default:
2573                         error_type = "I/O";
2574                         break;
2575                 }
2576                 printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n",
2577                                    __func__, error_type, req->rq_disk ?
2578                                    req->rq_disk->disk_name : "?",
2579                                    (unsigned long long)blk_rq_pos(req));
2580 
2581         }
2582 
2583         blk_account_io_completion(req, nr_bytes);
2584 
2585         total_bytes = 0;
2586         while (req->bio) {
2587                 struct bio *bio = req->bio;
2588                 unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes);
2589 
2590                 if (bio_bytes == bio->bi_iter.bi_size)
2591                         req->bio = bio->bi_next;
2592 
2593                 req_bio_endio(req, bio, bio_bytes, error);
2594 
2595                 total_bytes += bio_bytes;
2596                 nr_bytes -= bio_bytes;
2597 
2598                 if (!nr_bytes)
2599                         break;
2600         }
2601 
2602         /*
2603          * completely done
2604          */
2605         if (!req->bio) {
2606                 /*
2607                  * Reset counters so that the request stacking driver
2608                  * can find how many bytes remain in the request
2609                  * later.
2610                  */
2611                 req->__data_len = 0;
2612                 return false;
2613         }
2614 
2615         WARN_ON_ONCE(req->rq_flags & RQF_SPECIAL_PAYLOAD);
2616 
2617         req->__data_len -= total_bytes;
2618 
2619         /* update sector only for requests with clear definition of sector */
2620         if (req->cmd_type == REQ_TYPE_FS)
2621                 req->__sector += total_bytes >> 9;
2622 
2623         /* mixed attributes always follow the first bio */
2624         if (req->rq_flags & RQF_MIXED_MERGE) {
2625                 req->cmd_flags &= ~REQ_FAILFAST_MASK;
2626                 req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK;
2627         }
2628 
2629         /*
2630          * If total number of sectors is less than the first segment
2631          * size, something has gone terribly wrong.
2632          */
2633         if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
2634                 blk_dump_rq_flags(req, "request botched");
2635                 req->__data_len = blk_rq_cur_bytes(req);
2636         }
2637 
2638         /* recalculate the number of segments */
2639         blk_recalc_rq_segments(req);
2640 
2641         return true;
2642 }
2643 EXPORT_SYMBOL_GPL(blk_update_request);
2644 
2645 static bool blk_update_bidi_request(struct request *rq, int error,
2646                                     unsigned int nr_bytes,
2647                                     unsigned int bidi_bytes)
2648 {
2649         if (blk_update_request(rq, error, nr_bytes))
2650                 return true;
2651 
2652         /* Bidi request must be completed as a whole */
2653         if (unlikely(blk_bidi_rq(rq)) &&
2654             blk_update_request(rq->next_rq, error, bidi_bytes))
2655                 return true;
2656 
2657         if (blk_queue_add_random(rq->q))
2658                 add_disk_randomness(rq->rq_disk);
2659 
2660         return false;
2661 }
2662 
2663 /**
2664  * blk_unprep_request - unprepare a request
2665  * @req:        the request
2666  *
2667  * This function makes a request ready for complete resubmission (or
2668  * completion).  It happens only after all error handling is complete,
2669  * so represents the appropriate moment to deallocate any resources
2670  * that were allocated to the request in the prep_rq_fn.  The queue
2671  * lock is held when calling this.
2672  */
2673 void blk_unprep_request(struct request *req)
2674 {
2675         struct request_queue *q = req->q;
2676 
2677         req->rq_flags &= ~RQF_DONTPREP;
2678         if (q->unprep_rq_fn)
2679                 q->unprep_rq_fn(q, req);
2680 }
2681 EXPORT_SYMBOL_GPL(blk_unprep_request);
2682 
2683 /*
2684  * queue lock must be held
2685  */
2686 void blk_finish_request(struct request *req, int error)
2687 {
2688         struct request_queue *q = req->q;
2689 
2690         if (req->rq_flags & RQF_STATS)
2691                 blk_stat_add(&q->rq_stats[rq_data_dir(req)], req);
2692 
2693         if (req->rq_flags & RQF_QUEUED)
2694                 blk_queue_end_tag(q, req);
2695 
2696         BUG_ON(blk_queued_rq(req));
2697 
2698         if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS)
2699                 laptop_io_completion(&req->q->backing_dev_info);
2700 
2701         blk_delete_timer(req);
2702 
2703         if (req->rq_flags & RQF_DONTPREP)
2704                 blk_unprep_request(req);
2705 
2706         blk_account_io_done(req);
2707 
2708         if (req->end_io) {
2709                 wbt_done(req->q->rq_wb, &req->issue_stat);
2710                 req->end_io(req, error);
2711         } else {
2712                 if (blk_bidi_rq(req))
2713                         __blk_put_request(req->next_rq->q, req->next_rq);
2714 
2715                 __blk_put_request(q, req);
2716         }
2717 }
2718 EXPORT_SYMBOL(blk_finish_request);
2719 
2720 /**
2721  * blk_end_bidi_request - Complete a bidi request
2722  * @rq:         the request to complete
2723  * @error:      %0 for success, < %0 for error
2724  * @nr_bytes:   number of bytes to complete @rq
2725  * @bidi_bytes: number of bytes to complete @rq->next_rq
2726  *
2727  * Description:
2728  *     Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2729  *     Drivers that supports bidi can safely call this member for any
2730  *     type of request, bidi or uni.  In the later case @bidi_bytes is
2731  *     just ignored.
2732  *
2733  * Return:
2734  *     %false - we are done with this request
2735  *     %true  - still buffers pending for this request
2736  **/
2737 static bool blk_end_bidi_request(struct request *rq, int error,
2738                                  unsigned int nr_bytes, unsigned int bidi_bytes)
2739 {
2740         struct request_queue *q = rq->q;
2741         unsigned long flags;
2742 
2743         if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2744                 return true;
2745 
2746         spin_lock_irqsave(q->queue_lock, flags);
2747         blk_finish_request(rq, error);
2748         spin_unlock_irqrestore(q->queue_lock, flags);
2749 
2750         return false;
2751 }
2752 
2753 /**
2754  * __blk_end_bidi_request - Complete a bidi request with queue lock held
2755  * @rq:         the request to complete
2756  * @error:      %0 for success, < %0 for error
2757  * @nr_bytes:   number of bytes to complete @rq
2758  * @bidi_bytes: number of bytes to complete @rq->next_rq
2759  *
2760  * Description:
2761  *     Identical to blk_end_bidi_request() except that queue lock is
2762  *     assumed to be locked on entry and remains so on return.
2763  *
2764  * Return:
2765  *     %false - we are done with this request
2766  *     %true  - still buffers pending for this request
2767  **/
2768 bool __blk_end_bidi_request(struct request *rq, int error,
2769                                    unsigned int nr_bytes, unsigned int bidi_bytes)
2770 {
2771         if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2772                 return true;
2773 
2774         blk_finish_request(rq, error);
2775 
2776         return false;
2777 }
2778 
2779 /**
2780  * blk_end_request - Helper function for drivers to complete the request.
2781  * @rq:       the request being processed
2782  * @error:    %0 for success, < %0 for error
2783  * @nr_bytes: number of bytes to complete
2784  *
2785  * Description:
2786  *     Ends I/O on a number of bytes attached to @rq.
2787  *     If @rq has leftover, sets it up for the next range of segments.
2788  *
2789  * Return:
2790  *     %false - we are done with this request
2791  *     %true  - still buffers pending for this request
2792  **/
2793 bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
2794 {
2795         return blk_end_bidi_request(rq, error, nr_bytes, 0);
2796 }
2797 EXPORT_SYMBOL(blk_end_request);
2798 
2799 /**
2800  * blk_end_request_all - Helper function for drives to finish the request.
2801  * @rq: the request to finish
2802  * @error: %0 for success, < %0 for error
2803  *
2804  * Description:
2805  *     Completely finish @rq.
2806  */
2807 void blk_end_request_all(struct request *rq, int error)
2808 {
2809         bool pending;
2810         unsigned int bidi_bytes = 0;
2811 
2812         if (unlikely(blk_bidi_rq(rq)))
2813                 bidi_bytes = blk_rq_bytes(rq->next_rq);
2814 
2815         pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2816         BUG_ON(pending);
2817 }
2818 EXPORT_SYMBOL(blk_end_request_all);
2819 
2820 /**
2821  * blk_end_request_cur - Helper function to finish the current request chunk.
2822  * @rq: the request to finish the current chunk for
2823  * @error: %0 for success, < %0 for error
2824  *
2825  * Description:
2826  *     Complete the current consecutively mapped chunk from @rq.
2827  *
2828  * Return:
2829  *     %false - we are done with this request
2830  *     %true  - still buffers pending for this request
2831  */
2832 bool blk_end_request_cur(struct request *rq, int error)
2833 {
2834         return blk_end_request(rq, error, blk_rq_cur_bytes(rq));
2835 }
2836 EXPORT_SYMBOL(blk_end_request_cur);
2837 
2838 /**
2839  * blk_end_request_err - Finish a request till the next failure boundary.
2840  * @rq: the request to finish till the next failure boundary for
2841  * @error: must be negative errno
2842  *
2843  * Description:
2844  *     Complete @rq till the next failure boundary.
2845  *
2846  * Return:
2847  *     %false - we are done with this request
2848  *     %true  - still buffers pending for this request
2849  */
2850 bool blk_end_request_err(struct request *rq, int error)
2851 {
2852         WARN_ON(error >= 0);
2853         return blk_end_request(rq, error, blk_rq_err_bytes(rq));
2854 }
2855 EXPORT_SYMBOL_GPL(blk_end_request_err);
2856 
2857 /**
2858  * __blk_end_request - Helper function for drivers to complete the request.
2859  * @rq:       the request being processed
2860  * @error:    %0 for success, < %0 for error
2861  * @nr_bytes: number of bytes to complete
2862  *
2863  * Description:
2864  *     Must be called with queue lock held unlike blk_end_request().
2865  *
2866  * Return:
2867  *     %false - we are done with this request
2868  *     %true  - still buffers pending for this request
2869  **/
2870 bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
2871 {
2872         return __blk_end_bidi_request(rq, error, nr_bytes, 0);
2873 }
2874 EXPORT_SYMBOL(__blk_end_request);
2875 
2876 /**
2877  * __blk_end_request_all - Helper function for drives to finish the request.
2878  * @rq: the request to finish
2879  * @error: %0 for success, < %0 for error
2880  *
2881  * Description:
2882  *     Completely finish @rq.  Must be called with queue lock held.
2883  */
2884 void __blk_end_request_all(struct request *rq, int error)
2885 {
2886         bool pending;
2887         unsigned int bidi_bytes = 0;
2888 
2889         if (unlikely(blk_bidi_rq(rq)))
2890                 bidi_bytes = blk_rq_bytes(rq->next_rq);
2891 
2892         pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2893         BUG_ON(pending);
2894 }
2895 EXPORT_SYMBOL(__blk_end_request_all);
2896 
2897 /**
2898  * __blk_end_request_cur - Helper function to finish the current request chunk.
2899  * @rq: the request to finish the current chunk for
2900  * @error: %0 for success, < %0 for error
2901  *
2902  * Description:
2903  *     Complete the current consecutively mapped chunk from @rq.  Must
2904  *     be called with queue lock held.
2905  *
2906  * Return:
2907  *     %false - we are done with this request
2908  *     %true  - still buffers pending for this request
2909  */
2910 bool __blk_end_request_cur(struct request *rq, int error)
2911 {
2912         return __blk_end_request(rq, error, blk_rq_cur_bytes(rq));
2913 }
2914 EXPORT_SYMBOL(__blk_end_request_cur);
2915 
2916 /**
2917  * __blk_end_request_err - Finish a request till the next failure boundary.
2918  * @rq: the request to finish till the next failure boundary for
2919  * @error: must be negative errno
2920  *
2921  * Description:
2922  *     Complete @rq till the next failure boundary.  Must be called
2923  *     with queue lock held.
2924  *
2925  * Return:
2926  *     %false - we are done with this request
2927  *     %true  - still buffers pending for this request
2928  */
2929 bool __blk_end_request_err(struct request *rq, int error)
2930 {
2931         WARN_ON(error >= 0);
2932         return __blk_end_request(rq, error, blk_rq_err_bytes(rq));
2933 }
2934 EXPORT_SYMBOL_GPL(__blk_end_request_err);
2935 
2936 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
2937                      struct bio *bio)
2938 {
2939         if (bio_has_data(bio))
2940                 rq->nr_phys_segments = bio_phys_segments(q, bio);
2941 
2942         rq->__data_len = bio->bi_iter.bi_size;
2943         rq->bio = rq->biotail = bio;
2944 
2945         if (bio->bi_bdev)
2946                 rq->rq_disk = bio->bi_bdev->bd_disk;
2947 }
2948 
2949 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
2950 /**
2951  * rq_flush_dcache_pages - Helper function to flush all pages in a request
2952  * @rq: the request to be flushed
2953  *
2954  * Description:
2955  *     Flush all pages in @rq.
2956  */
2957 void rq_flush_dcache_pages(struct request *rq)
2958 {
2959         struct req_iterator iter;
2960         struct bio_vec bvec;
2961 
2962         rq_for_each_segment(bvec, rq, iter)
2963                 flush_dcache_page(bvec.bv_page);
2964 }
2965 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
2966 #endif
2967 
2968 /**
2969  * blk_lld_busy - Check if underlying low-level drivers of a device are busy
2970  * @q : the queue of the device being checked
2971  *
2972  * Description:
2973  *    Check if underlying low-level drivers of a device are busy.
2974  *    If the drivers want to export their busy state, they must set own
2975  *    exporting function using blk_queue_lld_busy() first.
2976  *
2977  *    Basically, this function is used only by request stacking drivers
2978  *    to stop dispatching requests to underlying devices when underlying
2979  *    devices are busy.  This behavior helps more I/O merging on the queue
2980  *    of the request stacking driver and prevents I/O throughput regression
2981  *    on burst I/O load.
2982  *
2983  * Return:
2984  *    0 - Not busy (The request stacking driver should dispatch request)
2985  *    1 - Busy (The request stacking driver should stop dispatching request)
2986  */
2987 int blk_lld_busy(struct request_queue *q)
2988 {
2989         if (q->lld_busy_fn)
2990                 return q->lld_busy_fn(q);
2991 
2992         return 0;
2993 }
2994 EXPORT_SYMBOL_GPL(blk_lld_busy);
2995 
2996 /**
2997  * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
2998  * @rq: the clone request to be cleaned up
2999  *
3000  * Description:
3001  *     Free all bios in @rq for a cloned request.
3002  */
3003 void blk_rq_unprep_clone(struct request *rq)
3004 {
3005         struct bio *bio;
3006 
3007         while ((bio = rq->bio) != NULL) {
3008                 rq->bio = bio->bi_next;
3009 
3010                 bio_put(bio);
3011         }
3012 }
3013 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
3014 
3015 /*
3016  * Copy attributes of the original request to the clone request.
3017  * The actual data parts (e.g. ->cmd, ->sense) are not copied.
3018  */
3019 static void __blk_rq_prep_clone(struct request *dst, struct request *src)
3020 {
3021         dst->cpu = src->cpu;
3022         dst->cmd_flags = src->cmd_flags | REQ_NOMERGE;
3023         dst->cmd_type = src->cmd_type;
3024         dst->__sector = blk_rq_pos(src);
3025         dst->__data_len = blk_rq_bytes(src);
3026         dst->nr_phys_segments = src->nr_phys_segments;
3027         dst->ioprio = src->ioprio;
3028         dst->extra_len = src->extra_len;
3029 }
3030 
3031 /**
3032  * blk_rq_prep_clone - Helper function to setup clone request
3033  * @rq: the request to be setup
3034  * @rq_src: original request to be cloned
3035  * @bs: bio_set that bios for clone are allocated from
3036  * @gfp_mask: memory allocation mask for bio
3037  * @bio_ctr: setup function to be called for each clone bio.
3038  *           Returns %0 for success, non %0 for failure.
3039  * @data: private data to be passed to @bio_ctr
3040  *
3041  * Description:
3042  *     Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
3043  *     The actual data parts of @rq_src (e.g. ->cmd, ->sense)
3044  *     are not copied, and copying such parts is the caller's responsibility.
3045  *     Also, pages which the original bios are pointing to are not copied
3046  *     and the cloned bios just point same pages.
3047  *     So cloned bios must be completed before original bios, which means
3048  *     the caller must complete @rq before @rq_src.
3049  */
3050 int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
3051                       struct bio_set *bs, gfp_t gfp_mask,
3052                       int (*bio_ctr)(struct bio *, struct bio *, void *),
3053                       void *data)
3054 {
3055         struct bio *bio, *bio_src;
3056 
3057         if (!bs)
3058                 bs = fs_bio_set;
3059 
3060         __rq_for_each_bio(bio_src, rq_src) {
3061                 bio = bio_clone_fast(bio_src, gfp_mask, bs);
3062                 if (!bio)
3063                         goto free_and_out;
3064 
3065                 if (bio_ctr && bio_ctr(bio, bio_src, data))
3066                         goto free_and_out;
3067 
3068                 if (rq->bio) {
3069                         rq->biotail->bi_next = bio;
3070                         rq->biotail = bio;
3071                 } else
3072                         rq->bio = rq->biotail = bio;
3073         }
3074 
3075         __blk_rq_prep_clone(rq, rq_src);
3076 
3077         return 0;
3078 
3079 free_and_out:
3080         if (bio)
3081                 bio_put(bio);
3082         blk_rq_unprep_clone(rq);
3083 
3084         return -ENOMEM;
3085 }
3086 EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
3087 
3088 int kblockd_schedule_work(struct work_struct *work)
3089 {
3090         return queue_work(kblockd_workqueue, work);
3091 }
3092 EXPORT_SYMBOL(kblockd_schedule_work);
3093 
3094 int kblockd_schedule_work_on(int cpu, struct work_struct *work)
3095 {
3096         return queue_work_on(cpu, kblockd_workqueue, work);
3097 }
3098 EXPORT_SYMBOL(kblockd_schedule_work_on);
3099 
3100 int kblockd_schedule_delayed_work(struct delayed_work *dwork,
3101                                   unsigned long delay)
3102 {
3103         return queue_delayed_work(kblockd_workqueue, dwork, delay);
3104 }
3105 EXPORT_SYMBOL(kblockd_schedule_delayed_work);
3106 
3107 int kblockd_schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
3108                                      unsigned long delay)
3109 {
3110         return queue_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
3111 }
3112 EXPORT_SYMBOL(kblockd_schedule_delayed_work_on);
3113 
3114 /**
3115  * blk_start_plug - initialize blk_plug and track it inside the task_struct
3116  * @plug:       The &struct blk_plug that needs to be initialized
3117  *
3118  * Description:
3119  *   Tracking blk_plug inside the task_struct will help with auto-flushing the
3120  *   pending I/O should the task end up blocking between blk_start_plug() and
3121  *   blk_finish_plug(). This is important from a performance perspective, but
3122  *   also ensures that we don't deadlock. For instance, if the task is blocking
3123  *   for a memory allocation, memory reclaim could end up wanting to free a
3124  *   page belonging to that request that is currently residing in our private
3125  *   plug. By flushing the pending I/O when the process goes to sleep, we avoid
3126  *   this kind of deadlock.
3127  */
3128 void blk_start_plug(struct blk_plug *plug)
3129 {
3130         struct task_struct *tsk = current;
3131 
3132         /*
3133          * If this is a nested plug, don't actually assign it.
3134          */
3135         if (tsk->plug)
3136                 return;
3137 
3138         INIT_LIST_HEAD(&plug->list);
3139         INIT_LIST_HEAD(&plug->mq_list);
3140         INIT_LIST_HEAD(&plug->cb_list);
3141         /*
3142          * Store ordering should not be needed here, since a potential
3143          * preempt will imply a full memory barrier
3144          */
3145         tsk->plug = plug;
3146 }
3147 EXPORT_SYMBOL(blk_start_plug);
3148 
3149 static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
3150 {
3151         struct request *rqa = container_of(a, struct request, queuelist);
3152         struct request *rqb = container_of(b, struct request, queuelist);
3153 
3154         return !(rqa->q < rqb->q ||
3155                 (rqa->q == rqb->q && blk_rq_pos(rqa) < blk_rq_pos(rqb)));
3156 }
3157 
3158 /*
3159  * If 'from_schedule' is true, then postpone the dispatch of requests
3160  * until a safe kblockd context. We due this to avoid accidental big
3161  * additional stack usage in driver dispatch, in places where the originally
3162  * plugger did not intend it.
3163  */
3164 static void queue_unplugged(struct request_queue *q, unsigned int depth,
3165                             bool from_schedule)
3166         __releases(q->queue_lock)
3167 {
3168         trace_block_unplug(q, depth, !from_schedule);
3169 
3170         if (from_schedule)
3171                 blk_run_queue_async(q);
3172         else
3173                 __blk_run_queue(q);
3174         spin_unlock(q->queue_lock);
3175 }
3176 
3177 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)
3178 {
3179         LIST_HEAD(callbacks);
3180 
3181         while (!list_empty(&plug->cb_list)) {
3182                 list_splice_init(&plug->cb_list, &callbacks);
3183 
3184                 while (!list_empty(&callbacks)) {
3185                         struct blk_plug_cb *cb = list_first_entry(&callbacks,
3186                                                           struct blk_plug_cb,
3187                                                           list);
3188                         list_del(&cb->list);
3189                         cb->callback(cb, from_schedule);
3190                 }
3191         }
3192 }
3193 
3194 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
3195                                       int size)
3196 {
3197         struct blk_plug *plug = current->plug;
3198         struct blk_plug_cb *cb;
3199 
3200         if (!plug)
3201                 return NULL;
3202 
3203         list_for_each_entry(cb, &plug->cb_list, list)
3204                 if (cb->callback == unplug && cb->data == data)
3205                         return cb;
3206 
3207         /* Not currently on the callback list */
3208         BUG_ON(size < sizeof(*cb));
3209         cb = kzalloc(size, GFP_ATOMIC);
3210         if (cb) {
3211                 cb->data = data;
3212                 cb->callback = unplug;
3213                 list_add(&cb->list, &plug->cb_list);
3214         }
3215         return cb;
3216 }
3217 EXPORT_SYMBOL(blk_check_plugged);
3218 
3219 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
3220 {
3221         struct request_queue *q;
3222         unsigned long flags;
3223         struct request *rq;
3224         LIST_HEAD(list);
3225         unsigned int depth;
3226 
3227         flush_plug_callbacks(plug, from_schedule);
3228 
3229         if (!list_empty(&plug->mq_list))
3230                 blk_mq_flush_plug_list(plug, from_schedule);
3231 
3232         if (list_empty(&plug->list))
3233                 return;
3234 
3235         list_splice_init(&plug->list, &list);
3236 
3237         list_sort(NULL, &list, plug_rq_cmp);
3238 
3239         q = NULL;
3240         depth = 0;
3241 
3242         /*
3243          * Save and disable interrupts here, to avoid doing it for every
3244          * queue lock we have to take.
3245          */
3246         local_irq_save(flags);
3247         while (!list_empty(&list)) {
3248                 rq = list_entry_rq(list.next);
3249                 list_del_init(&rq->queuelist);
3250                 BUG_ON(!rq->q);
3251                 if (rq->q != q) {
3252                         /*
3253                          * This drops the queue lock
3254                          */
3255                         if (q)
3256                                 queue_unplugged(q, depth, from_schedule);
3257                         q = rq->q;
3258                         depth = 0;
3259                         spin_lock(q->queue_lock);
3260                 }
3261 
3262                 /*
3263                  * Short-circuit if @q is dead
3264                  */
3265                 if (unlikely(blk_queue_dying(q))) {
3266                         __blk_end_request_all(rq, -ENODEV);
3267                         continue;
3268                 }
3269 
3270                 /*
3271                  * rq is already accounted, so use raw insert
3272                  */
3273                 if (rq->cmd_flags & (REQ_PREFLUSH | REQ_FUA))
3274                         __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH);
3275                 else
3276                         __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);
3277 
3278                 depth++;
3279         }
3280 
3281         /*
3282          * This drops the queue lock
3283          */
3284         if (q)
3285                 queue_unplugged(q, depth, from_schedule);
3286 
3287         local_irq_restore(flags);
3288 }
3289 
3290 void blk_finish_plug(struct blk_plug *plug)
3291 {
3292         if (plug != current->plug)
3293                 return;
3294         blk_flush_plug_list(plug, false);
3295 
3296         current->plug = NULL;
3297 }
3298 EXPORT_SYMBOL(blk_finish_plug);
3299 
3300 #ifdef CONFIG_PM
3301 /**
3302  * blk_pm_runtime_init - Block layer runtime PM initialization routine
3303  * @q: the queue of the device
3304  * @dev: the device the queue belongs to
3305  *
3306  * Description:
3307  *    Initialize runtime-PM-related fields for @q and start auto suspend for
3308  *    @dev. Drivers that want to take advantage of request-based runtime PM
3309  *    should call this function after @dev has been initialized, and its
3310  *    request queue @q has been allocated, and runtime PM for it can not happen
3311  *    yet(either due to disabled/forbidden or its usage_count > 0). In most
3312  *    cases, driver should call this function before any I/O has taken place.
3313  *
3314  *    This function takes care of setting up using auto suspend for the device,
3315  *    the autosuspend delay is set to -1 to make runtime suspend impossible
3316  *    until an updated value is either set by user or by driver. Drivers do
3317  *    not need to touch other autosuspend settings.
3318  *
3319  *    The block layer runtime PM is request based, so only works for drivers
3320  *    that use request as their IO unit instead of those directly use bio's.
3321  */
3322 void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
3323 {
3324         q->dev = dev;
3325         q->rpm_status = RPM_ACTIVE;
3326         pm_runtime_set_autosuspend_delay(q->dev, -1);
3327         pm_runtime_use_autosuspend(q->dev);
3328 }
3329 EXPORT_SYMBOL(blk_pm_runtime_init);
3330 
3331 /**
3332  * blk_pre_runtime_suspend - Pre runtime suspend check
3333  * @q: the queue of the device
3334  *
3335  * Description:
3336  *    This function will check if runtime suspend is allowed for the device
3337  *    by examining if there are any requests pending in the queue. If there
3338  *    are requests pending, the device can not be runtime suspended; otherwise,
3339  *    the queue's status will be updated to SUSPENDING and the driver can
3340  *    proceed to suspend the device.
3341  *
3342  *    For the not allowed case, we mark last busy for the device so that
3343  *    runtime PM core will try to autosuspend it some time later.
3344  *
3345  *    This function should be called near the start of the device's
3346  *    runtime_suspend callback.
3347  *
3348  * Return:
3349  *    0         - OK to runtime suspend the device
3350  *    -EBUSY    - Device should not be runtime suspended
3351  */
3352 int blk_pre_runtime_suspend(struct request_queue *q)
3353 {
3354         int ret = 0;
3355 
3356         if (!q->dev)
3357                 return ret;
3358 
3359         spin_lock_irq(q->queue_lock);
3360         if (q->nr_pending) {
3361                 ret = -EBUSY;
3362                 pm_runtime_mark_last_busy(q->dev);
3363         } else {
3364                 q->rpm_status = RPM_SUSPENDING;
3365         }
3366         spin_unlock_irq(q->queue_lock);
3367         return ret;
3368 }
3369 EXPORT_SYMBOL(blk_pre_runtime_suspend);
3370 
3371 /**
3372  * blk_post_runtime_suspend - Post runtime suspend processing
3373  * @q: the queue of the device
3374  * @err: return value of the device's runtime_suspend function
3375  *
3376  * Description:
3377  *    Update the queue's runtime status according to the return value of the
3378  *    device's runtime suspend function and mark last busy for the device so
3379  *    that PM core will try to auto suspend the device at a later time.
3380  *
3381  *    This function should be called near the end of the device's
3382  *    runtime_suspend callback.
3383  */
3384 void blk_post_runtime_suspend(struct request_queue *q, int err)
3385 {
3386         if (!q->dev)
3387                 return;
3388 
3389         spin_lock_irq(q->queue_lock);
3390         if (!err) {
3391                 q->rpm_status = RPM_SUSPENDED;
3392         } else {
3393                 q->rpm_status = RPM_ACTIVE;
3394                 pm_runtime_mark_last_busy(q->dev);
3395         }
3396         spin_unlock_irq(q->queue_lock);
3397 }
3398 EXPORT_SYMBOL(blk_post_runtime_suspend);
3399 
3400 /**
3401  * blk_pre_runtime_resume - Pre runtime resume processing
3402  * @q: the queue of the device
3403  *
3404  * Description:
3405  *    Update the queue's runtime status to RESUMING in preparation for the
3406  *    runtime resume of the device.
3407  *
3408  *    This function should be called near the start of the device's
3409  *    runtime_resume callback.
3410  */
3411 void blk_pre_runtime_resume(struct request_queue *q)
3412 {
3413         if (!q->dev)
3414                 return;
3415 
3416         spin_lock_irq(q->queue_lock);
3417         q->rpm_status = RPM_RESUMING;
3418         spin_unlock_irq(q->queue_lock);
3419 }
3420 EXPORT_SYMBOL(blk_pre_runtime_resume);
3421 
3422 /**
3423  * blk_post_runtime_resume - Post runtime resume processing
3424  * @q: the queue of the device
3425  * @err: return value of the device's runtime_resume function
3426  *
3427  * Description:
3428  *    Update the queue's runtime status according to the return value of the
3429  *    device's runtime_resume function. If it is successfully resumed, process
3430  *    the requests that are queued into the device's queue when it is resuming
3431  *    and then mark last busy and initiate autosuspend for it.
3432  *
3433  *    This function should be called near the end of the device's
3434  *    runtime_resume callback.
3435  */
3436 void blk_post_runtime_resume(struct request_queue *q, int err)
3437 {
3438         if (!q->dev)
3439                 return;
3440 
3441         spin_lock_irq(q->queue_lock);
3442         if (!err) {
3443                 q->rpm_status = RPM_ACTIVE;
3444                 __blk_run_queue(q);
3445                 pm_runtime_mark_last_busy(q->dev);
3446                 pm_request_autosuspend(q->dev);
3447         } else {
3448                 q->rpm_status = RPM_SUSPENDED;
3449         }
3450         spin_unlock_irq(q->queue_lock);
3451 }
3452 EXPORT_SYMBOL(blk_post_runtime_resume);
3453 
3454 /**
3455  * blk_set_runtime_active - Force runtime status of the queue to be active
3456  * @q: the queue of the device
3457  *
3458  * If the device is left runtime suspended during system suspend the resume
3459  * hook typically resumes the device and corrects runtime status
3460  * accordingly. However, that does not affect the queue runtime PM status
3461  * which is still "suspended". This prevents processing requests from the
3462  * queue.
3463  *
3464  * This function can be used in driver's resume hook to correct queue
3465  * runtime PM status and re-enable peeking requests from the queue. It
3466  * should be called before first request is added to the queue.
3467  */
3468 void blk_set_runtime_active(struct request_queue *q)
3469 {
3470         spin_lock_irq(q->queue_lock);
3471         q->rpm_status = RPM_ACTIVE;
3472         pm_runtime_mark_last_busy(q->dev);
3473         pm_request_autosuspend(q->dev);
3474         spin_unlock_irq(q->queue_lock);
3475 }
3476 EXPORT_SYMBOL(blk_set_runtime_active);
3477 #endif
3478 
3479 int __init blk_dev_init(void)
3480 {
3481         BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS));
3482         BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
3483                         FIELD_SIZEOF(struct request, cmd_flags));
3484         BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
3485                         FIELD_SIZEOF(struct bio, bi_opf));
3486 
3487         /* used for unplugging and affects IO latency/throughput - HIGHPRI */
3488         kblockd_workqueue = alloc_workqueue("kblockd",
3489                                             WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
3490         if (!kblockd_workqueue)
3491                 panic("Failed to create kblockd\n");
3492 
3493         request_cachep = kmem_cache_create("blkdev_requests",
3494                         sizeof(struct request), 0, SLAB_PANIC, NULL);
3495 
3496         blk_requestq_cachep = kmem_cache_create("request_queue",
3497                         sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
3498 
3499         return 0;
3500 }
3501 

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