~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/block/blk-core.c

Version: ~ [ linux-5.4-rc3 ] ~ [ linux-5.3.6 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.79 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.149 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.196 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.196 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.75 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

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

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp