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>
8 * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
12 * This handles all read/write requests to block devices
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>
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 #include <linux/debugfs.h>
38 #define CREATE_TRACE_POINTS
39 #include <trace/events/block.h>
43 #include "blk-mq-sched.h"
46 #ifdef CONFIG_DEBUG_FS
47 struct dentry
*blk_debugfs_root
;
50 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap
);
51 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap
);
52 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete
);
53 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split
);
54 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug
);
56 DEFINE_IDA(blk_queue_ida
);
59 * For the allocated request tables
61 struct kmem_cache
*request_cachep
;
64 * For queue allocation
66 struct kmem_cache
*blk_requestq_cachep
;
69 * Controlling structure to kblockd
71 static struct workqueue_struct
*kblockd_workqueue
;
73 static void blk_clear_congested(struct request_list
*rl
, int sync
)
75 #ifdef CONFIG_CGROUP_WRITEBACK
76 clear_wb_congested(rl
->blkg
->wb_congested
, sync
);
79 * If !CGROUP_WRITEBACK, all blkg's map to bdi->wb and we shouldn't
80 * flip its congestion state for events on other blkcgs.
82 if (rl
== &rl
->q
->root_rl
)
83 clear_wb_congested(rl
->q
->backing_dev_info
->wb
.congested
, sync
);
87 static void blk_set_congested(struct request_list
*rl
, int sync
)
89 #ifdef CONFIG_CGROUP_WRITEBACK
90 set_wb_congested(rl
->blkg
->wb_congested
, sync
);
92 /* see blk_clear_congested() */
93 if (rl
== &rl
->q
->root_rl
)
94 set_wb_congested(rl
->q
->backing_dev_info
->wb
.congested
, sync
);
98 void blk_queue_congestion_threshold(struct request_queue
*q
)
102 nr
= q
->nr_requests
- (q
->nr_requests
/ 8) + 1;
103 if (nr
> q
->nr_requests
)
105 q
->nr_congestion_on
= nr
;
107 nr
= q
->nr_requests
- (q
->nr_requests
/ 8) - (q
->nr_requests
/ 16) - 1;
110 q
->nr_congestion_off
= nr
;
113 void blk_rq_init(struct request_queue
*q
, struct request
*rq
)
115 memset(rq
, 0, sizeof(*rq
));
117 INIT_LIST_HEAD(&rq
->queuelist
);
118 INIT_LIST_HEAD(&rq
->timeout_list
);
121 rq
->__sector
= (sector_t
) -1;
122 INIT_HLIST_NODE(&rq
->hash
);
123 RB_CLEAR_NODE(&rq
->rb_node
);
125 rq
->internal_tag
= -1;
126 rq
->start_time
= jiffies
;
127 set_start_time_ns(rq
);
130 EXPORT_SYMBOL(blk_rq_init
);
132 static const struct {
136 [BLK_STS_OK
] = { 0, "" },
137 [BLK_STS_NOTSUPP
] = { -EOPNOTSUPP
, "operation not supported" },
138 [BLK_STS_TIMEOUT
] = { -ETIMEDOUT
, "timeout" },
139 [BLK_STS_NOSPC
] = { -ENOSPC
, "critical space allocation" },
140 [BLK_STS_TRANSPORT
] = { -ENOLINK
, "recoverable transport" },
141 [BLK_STS_TARGET
] = { -EREMOTEIO
, "critical target" },
142 [BLK_STS_NEXUS
] = { -EBADE
, "critical nexus" },
143 [BLK_STS_MEDIUM
] = { -ENODATA
, "critical medium" },
144 [BLK_STS_PROTECTION
] = { -EILSEQ
, "protection" },
145 [BLK_STS_RESOURCE
] = { -ENOMEM
, "kernel resource" },
146 [BLK_STS_AGAIN
] = { -EAGAIN
, "nonblocking retry" },
148 /* device mapper special case, should not leak out: */
149 [BLK_STS_DM_REQUEUE
] = { -EREMCHG
, "dm internal retry" },
151 /* everything else not covered above: */
152 [BLK_STS_IOERR
] = { -EIO
, "I/O" },
155 blk_status_t
errno_to_blk_status(int errno
)
159 for (i
= 0; i
< ARRAY_SIZE(blk_errors
); i
++) {
160 if (blk_errors
[i
].errno
== errno
)
161 return (__force blk_status_t
)i
;
164 return BLK_STS_IOERR
;
166 EXPORT_SYMBOL_GPL(errno_to_blk_status
);
168 int blk_status_to_errno(blk_status_t status
)
170 int idx
= (__force
int)status
;
172 if (WARN_ON_ONCE(idx
>= ARRAY_SIZE(blk_errors
)))
174 return blk_errors
[idx
].errno
;
176 EXPORT_SYMBOL_GPL(blk_status_to_errno
);
178 static void print_req_error(struct request
*req
, blk_status_t status
)
180 int idx
= (__force
int)status
;
182 if (WARN_ON_ONCE(idx
>= ARRAY_SIZE(blk_errors
)))
185 printk_ratelimited(KERN_ERR
"%s: %s error, dev %s, sector %llu\n",
186 __func__
, blk_errors
[idx
].name
, req
->rq_disk
?
187 req
->rq_disk
->disk_name
: "?",
188 (unsigned long long)blk_rq_pos(req
));
191 static void req_bio_endio(struct request
*rq
, struct bio
*bio
,
192 unsigned int nbytes
, blk_status_t error
)
195 bio
->bi_status
= error
;
197 if (unlikely(rq
->rq_flags
& RQF_QUIET
))
198 bio_set_flag(bio
, BIO_QUIET
);
200 bio_advance(bio
, nbytes
);
202 /* don't actually finish bio if it's part of flush sequence */
203 if (bio
->bi_iter
.bi_size
== 0 && !(rq
->rq_flags
& RQF_FLUSH_SEQ
))
207 void blk_dump_rq_flags(struct request
*rq
, char *msg
)
209 printk(KERN_INFO
"%s: dev %s: flags=%llx\n", msg
,
210 rq
->rq_disk
? rq
->rq_disk
->disk_name
: "?",
211 (unsigned long long) rq
->cmd_flags
);
213 printk(KERN_INFO
" sector %llu, nr/cnr %u/%u\n",
214 (unsigned long long)blk_rq_pos(rq
),
215 blk_rq_sectors(rq
), blk_rq_cur_sectors(rq
));
216 printk(KERN_INFO
" bio %p, biotail %p, len %u\n",
217 rq
->bio
, rq
->biotail
, blk_rq_bytes(rq
));
219 EXPORT_SYMBOL(blk_dump_rq_flags
);
221 static void blk_delay_work(struct work_struct
*work
)
223 struct request_queue
*q
;
225 q
= container_of(work
, struct request_queue
, delay_work
.work
);
226 spin_lock_irq(q
->queue_lock
);
228 spin_unlock_irq(q
->queue_lock
);
232 * blk_delay_queue - restart queueing after defined interval
233 * @q: The &struct request_queue in question
234 * @msecs: Delay in msecs
237 * Sometimes queueing needs to be postponed for a little while, to allow
238 * resources to come back. This function will make sure that queueing is
239 * restarted around the specified time.
241 void blk_delay_queue(struct request_queue
*q
, unsigned long msecs
)
243 lockdep_assert_held(q
->queue_lock
);
244 WARN_ON_ONCE(q
->mq_ops
);
246 if (likely(!blk_queue_dead(q
)))
247 queue_delayed_work(kblockd_workqueue
, &q
->delay_work
,
248 msecs_to_jiffies(msecs
));
250 EXPORT_SYMBOL(blk_delay_queue
);
253 * blk_start_queue_async - asynchronously restart a previously stopped queue
254 * @q: The &struct request_queue in question
257 * blk_start_queue_async() will clear the stop flag on the queue, and
258 * ensure that the request_fn for the queue is run from an async
261 void blk_start_queue_async(struct request_queue
*q
)
263 lockdep_assert_held(q
->queue_lock
);
264 WARN_ON_ONCE(q
->mq_ops
);
266 queue_flag_clear(QUEUE_FLAG_STOPPED
, q
);
267 blk_run_queue_async(q
);
269 EXPORT_SYMBOL(blk_start_queue_async
);
272 * blk_start_queue - restart a previously stopped queue
273 * @q: The &struct request_queue in question
276 * blk_start_queue() will clear the stop flag on the queue, and call
277 * the request_fn for the queue if it was in a stopped state when
278 * entered. Also see blk_stop_queue().
280 void blk_start_queue(struct request_queue
*q
)
282 lockdep_assert_held(q
->queue_lock
);
283 WARN_ON(!in_interrupt() && !irqs_disabled());
284 WARN_ON_ONCE(q
->mq_ops
);
286 queue_flag_clear(QUEUE_FLAG_STOPPED
, q
);
289 EXPORT_SYMBOL(blk_start_queue
);
292 * blk_stop_queue - stop a queue
293 * @q: The &struct request_queue in question
296 * The Linux block layer assumes that a block driver will consume all
297 * entries on the request queue when the request_fn strategy is called.
298 * Often this will not happen, because of hardware limitations (queue
299 * depth settings). If a device driver gets a 'queue full' response,
300 * or if it simply chooses not to queue more I/O at one point, it can
301 * call this function to prevent the request_fn from being called until
302 * the driver has signalled it's ready to go again. This happens by calling
303 * blk_start_queue() to restart queue operations.
305 void blk_stop_queue(struct request_queue
*q
)
307 lockdep_assert_held(q
->queue_lock
);
308 WARN_ON_ONCE(q
->mq_ops
);
310 cancel_delayed_work(&q
->delay_work
);
311 queue_flag_set(QUEUE_FLAG_STOPPED
, q
);
313 EXPORT_SYMBOL(blk_stop_queue
);
316 * blk_sync_queue - cancel any pending callbacks on a queue
320 * The block layer may perform asynchronous callback activity
321 * on a queue, such as calling the unplug function after a timeout.
322 * A block device may call blk_sync_queue to ensure that any
323 * such activity is cancelled, thus allowing it to release resources
324 * that the callbacks might use. The caller must already have made sure
325 * that its ->make_request_fn will not re-add plugging prior to calling
328 * This function does not cancel any asynchronous activity arising
329 * out of elevator or throttling code. That would require elevator_exit()
330 * and blkcg_exit_queue() to be called with queue lock initialized.
333 void blk_sync_queue(struct request_queue
*q
)
335 del_timer_sync(&q
->timeout
);
336 cancel_work_sync(&q
->timeout_work
);
339 struct blk_mq_hw_ctx
*hctx
;
342 cancel_delayed_work_sync(&q
->requeue_work
);
343 queue_for_each_hw_ctx(q
, hctx
, i
)
344 cancel_delayed_work_sync(&hctx
->run_work
);
346 cancel_delayed_work_sync(&q
->delay_work
);
349 EXPORT_SYMBOL(blk_sync_queue
);
352 * __blk_run_queue_uncond - run a queue whether or not it has been stopped
353 * @q: The queue to run
356 * Invoke request handling on a queue if there are any pending requests.
357 * May be used to restart request handling after a request has completed.
358 * This variant runs the queue whether or not the queue has been
359 * stopped. Must be called with the queue lock held and interrupts
360 * disabled. See also @blk_run_queue.
362 inline void __blk_run_queue_uncond(struct request_queue
*q
)
364 lockdep_assert_held(q
->queue_lock
);
365 WARN_ON_ONCE(q
->mq_ops
);
367 if (unlikely(blk_queue_dead(q
)))
371 * Some request_fn implementations, e.g. scsi_request_fn(), unlock
372 * the queue lock internally. As a result multiple threads may be
373 * running such a request function concurrently. Keep track of the
374 * number of active request_fn invocations such that blk_drain_queue()
375 * can wait until all these request_fn calls have finished.
377 q
->request_fn_active
++;
379 q
->request_fn_active
--;
381 EXPORT_SYMBOL_GPL(__blk_run_queue_uncond
);
384 * __blk_run_queue - run a single device queue
385 * @q: The queue to run
388 * See @blk_run_queue.
390 void __blk_run_queue(struct request_queue
*q
)
392 lockdep_assert_held(q
->queue_lock
);
393 WARN_ON_ONCE(q
->mq_ops
);
395 if (unlikely(blk_queue_stopped(q
)))
398 __blk_run_queue_uncond(q
);
400 EXPORT_SYMBOL(__blk_run_queue
);
403 * blk_run_queue_async - run a single device queue in workqueue context
404 * @q: The queue to run
407 * Tells kblockd to perform the equivalent of @blk_run_queue on behalf
411 * Since it is not allowed to run q->delay_work after blk_cleanup_queue()
412 * has canceled q->delay_work, callers must hold the queue lock to avoid
413 * race conditions between blk_cleanup_queue() and blk_run_queue_async().
415 void blk_run_queue_async(struct request_queue
*q
)
417 lockdep_assert_held(q
->queue_lock
);
418 WARN_ON_ONCE(q
->mq_ops
);
420 if (likely(!blk_queue_stopped(q
) && !blk_queue_dead(q
)))
421 mod_delayed_work(kblockd_workqueue
, &q
->delay_work
, 0);
423 EXPORT_SYMBOL(blk_run_queue_async
);
426 * blk_run_queue - run a single device queue
427 * @q: The queue to run
430 * Invoke request handling on this queue, if it has pending work to do.
431 * May be used to restart queueing when a request has completed.
433 void blk_run_queue(struct request_queue
*q
)
437 WARN_ON_ONCE(q
->mq_ops
);
439 spin_lock_irqsave(q
->queue_lock
, flags
);
441 spin_unlock_irqrestore(q
->queue_lock
, flags
);
443 EXPORT_SYMBOL(blk_run_queue
);
445 void blk_put_queue(struct request_queue
*q
)
447 kobject_put(&q
->kobj
);
449 EXPORT_SYMBOL(blk_put_queue
);
452 * __blk_drain_queue - drain requests from request_queue
454 * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
456 * Drain requests from @q. If @drain_all is set, all requests are drained.
457 * If not, only ELVPRIV requests are drained. The caller is responsible
458 * for ensuring that no new requests which need to be drained are queued.
460 static void __blk_drain_queue(struct request_queue
*q
, bool drain_all
)
461 __releases(q
->queue_lock
)
462 __acquires(q
->queue_lock
)
466 lockdep_assert_held(q
->queue_lock
);
467 WARN_ON_ONCE(q
->mq_ops
);
473 * The caller might be trying to drain @q before its
474 * elevator is initialized.
477 elv_drain_elevator(q
);
479 blkcg_drain_queue(q
);
482 * This function might be called on a queue which failed
483 * driver init after queue creation or is not yet fully
484 * active yet. Some drivers (e.g. fd and loop) get unhappy
485 * in such cases. Kick queue iff dispatch queue has
486 * something on it and @q has request_fn set.
488 if (!list_empty(&q
->queue_head
) && q
->request_fn
)
491 drain
|= q
->nr_rqs_elvpriv
;
492 drain
|= q
->request_fn_active
;
495 * Unfortunately, requests are queued at and tracked from
496 * multiple places and there's no single counter which can
497 * be drained. Check all the queues and counters.
500 struct blk_flush_queue
*fq
= blk_get_flush_queue(q
, NULL
);
501 drain
|= !list_empty(&q
->queue_head
);
502 for (i
= 0; i
< 2; i
++) {
503 drain
|= q
->nr_rqs
[i
];
504 drain
|= q
->in_flight
[i
];
506 drain
|= !list_empty(&fq
->flush_queue
[i
]);
513 spin_unlock_irq(q
->queue_lock
);
517 spin_lock_irq(q
->queue_lock
);
521 * With queue marked dead, any woken up waiter will fail the
522 * allocation path, so the wakeup chaining is lost and we're
523 * left with hung waiters. We need to wake up those waiters.
526 struct request_list
*rl
;
528 blk_queue_for_each_rl(rl
, q
)
529 for (i
= 0; i
< ARRAY_SIZE(rl
->wait
); i
++)
530 wake_up_all(&rl
->wait
[i
]);
534 void blk_drain_queue(struct request_queue
*q
)
536 spin_lock_irq(q
->queue_lock
);
537 __blk_drain_queue(q
, true);
538 spin_unlock_irq(q
->queue_lock
);
542 * blk_queue_bypass_start - enter queue bypass mode
543 * @q: queue of interest
545 * In bypass mode, only the dispatch FIFO queue of @q is used. This
546 * function makes @q enter bypass mode and drains all requests which were
547 * throttled or issued before. On return, it's guaranteed that no request
548 * is being throttled or has ELVPRIV set and blk_queue_bypass() %true
549 * inside queue or RCU read lock.
551 void blk_queue_bypass_start(struct request_queue
*q
)
553 WARN_ON_ONCE(q
->mq_ops
);
555 spin_lock_irq(q
->queue_lock
);
557 queue_flag_set(QUEUE_FLAG_BYPASS
, q
);
558 spin_unlock_irq(q
->queue_lock
);
561 * Queues start drained. Skip actual draining till init is
562 * complete. This avoids lenghty delays during queue init which
563 * can happen many times during boot.
565 if (blk_queue_init_done(q
)) {
566 spin_lock_irq(q
->queue_lock
);
567 __blk_drain_queue(q
, false);
568 spin_unlock_irq(q
->queue_lock
);
570 /* ensure blk_queue_bypass() is %true inside RCU read lock */
574 EXPORT_SYMBOL_GPL(blk_queue_bypass_start
);
577 * blk_queue_bypass_end - leave queue bypass mode
578 * @q: queue of interest
580 * Leave bypass mode and restore the normal queueing behavior.
582 * Note: although blk_queue_bypass_start() is only called for blk-sq queues,
583 * this function is called for both blk-sq and blk-mq queues.
585 void blk_queue_bypass_end(struct request_queue
*q
)
587 spin_lock_irq(q
->queue_lock
);
588 if (!--q
->bypass_depth
)
589 queue_flag_clear(QUEUE_FLAG_BYPASS
, q
);
590 WARN_ON_ONCE(q
->bypass_depth
< 0);
591 spin_unlock_irq(q
->queue_lock
);
593 EXPORT_SYMBOL_GPL(blk_queue_bypass_end
);
595 void blk_set_queue_dying(struct request_queue
*q
)
597 spin_lock_irq(q
->queue_lock
);
598 queue_flag_set(QUEUE_FLAG_DYING
, q
);
599 spin_unlock_irq(q
->queue_lock
);
602 * When queue DYING flag is set, we need to block new req
603 * entering queue, so we call blk_freeze_queue_start() to
604 * prevent I/O from crossing blk_queue_enter().
606 blk_freeze_queue_start(q
);
609 blk_mq_wake_waiters(q
);
611 struct request_list
*rl
;
613 spin_lock_irq(q
->queue_lock
);
614 blk_queue_for_each_rl(rl
, q
) {
616 wake_up_all(&rl
->wait
[BLK_RW_SYNC
]);
617 wake_up_all(&rl
->wait
[BLK_RW_ASYNC
]);
620 spin_unlock_irq(q
->queue_lock
);
623 EXPORT_SYMBOL_GPL(blk_set_queue_dying
);
626 * blk_cleanup_queue - shutdown a request queue
627 * @q: request queue to shutdown
629 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
630 * put it. All future requests will be failed immediately with -ENODEV.
632 void blk_cleanup_queue(struct request_queue
*q
)
634 spinlock_t
*lock
= q
->queue_lock
;
636 /* mark @q DYING, no new request or merges will be allowed afterwards */
637 mutex_lock(&q
->sysfs_lock
);
638 blk_set_queue_dying(q
);
642 * A dying queue is permanently in bypass mode till released. Note
643 * that, unlike blk_queue_bypass_start(), we aren't performing
644 * synchronize_rcu() after entering bypass mode to avoid the delay
645 * as some drivers create and destroy a lot of queues while
646 * probing. This is still safe because blk_release_queue() will be
647 * called only after the queue refcnt drops to zero and nothing,
648 * RCU or not, would be traversing the queue by then.
651 queue_flag_set(QUEUE_FLAG_BYPASS
, q
);
653 queue_flag_set(QUEUE_FLAG_NOMERGES
, q
);
654 queue_flag_set(QUEUE_FLAG_NOXMERGES
, q
);
655 queue_flag_set(QUEUE_FLAG_DYING
, q
);
656 spin_unlock_irq(lock
);
657 mutex_unlock(&q
->sysfs_lock
);
660 * Drain all requests queued before DYING marking. Set DEAD flag to
661 * prevent that q->request_fn() gets invoked after draining finished.
665 queue_flag_set(QUEUE_FLAG_DEAD
, q
);
666 spin_unlock_irq(lock
);
669 * make sure all in-progress dispatch are completed because
670 * blk_freeze_queue() can only complete all requests, and
671 * dispatch may still be in-progress since we dispatch requests
672 * from more than one contexts
675 blk_mq_quiesce_queue(q
);
677 /* for synchronous bio-based driver finish in-flight integrity i/o */
678 blk_flush_integrity();
680 /* @q won't process any more request, flush async actions */
681 del_timer_sync(&q
->backing_dev_info
->laptop_mode_wb_timer
);
685 blk_mq_free_queue(q
);
686 percpu_ref_exit(&q
->q_usage_counter
);
689 if (q
->queue_lock
!= &q
->__queue_lock
)
690 q
->queue_lock
= &q
->__queue_lock
;
691 spin_unlock_irq(lock
);
693 /* @q is and will stay empty, shutdown and put */
696 EXPORT_SYMBOL(blk_cleanup_queue
);
698 /* Allocate memory local to the request queue */
699 static void *alloc_request_simple(gfp_t gfp_mask
, void *data
)
701 struct request_queue
*q
= data
;
703 return kmem_cache_alloc_node(request_cachep
, gfp_mask
, q
->node
);
706 static void free_request_simple(void *element
, void *data
)
708 kmem_cache_free(request_cachep
, element
);
711 static void *alloc_request_size(gfp_t gfp_mask
, void *data
)
713 struct request_queue
*q
= data
;
716 rq
= kmalloc_node(sizeof(struct request
) + q
->cmd_size
, gfp_mask
,
718 if (rq
&& q
->init_rq_fn
&& q
->init_rq_fn(q
, rq
, gfp_mask
) < 0) {
725 static void free_request_size(void *element
, void *data
)
727 struct request_queue
*q
= data
;
730 q
->exit_rq_fn(q
, element
);
734 int blk_init_rl(struct request_list
*rl
, struct request_queue
*q
,
737 if (unlikely(rl
->rq_pool
))
741 rl
->count
[BLK_RW_SYNC
] = rl
->count
[BLK_RW_ASYNC
] = 0;
742 rl
->starved
[BLK_RW_SYNC
] = rl
->starved
[BLK_RW_ASYNC
] = 0;
743 init_waitqueue_head(&rl
->wait
[BLK_RW_SYNC
]);
744 init_waitqueue_head(&rl
->wait
[BLK_RW_ASYNC
]);
747 rl
->rq_pool
= mempool_create_node(BLKDEV_MIN_RQ
,
748 alloc_request_size
, free_request_size
,
749 q
, gfp_mask
, q
->node
);
751 rl
->rq_pool
= mempool_create_node(BLKDEV_MIN_RQ
,
752 alloc_request_simple
, free_request_simple
,
753 q
, gfp_mask
, q
->node
);
758 if (rl
!= &q
->root_rl
)
759 WARN_ON_ONCE(!blk_get_queue(q
));
764 void blk_exit_rl(struct request_queue
*q
, struct request_list
*rl
)
767 mempool_destroy(rl
->rq_pool
);
768 if (rl
!= &q
->root_rl
)
773 struct request_queue
*blk_alloc_queue(gfp_t gfp_mask
)
775 return blk_alloc_queue_node(gfp_mask
, NUMA_NO_NODE
);
777 EXPORT_SYMBOL(blk_alloc_queue
);
779 int blk_queue_enter(struct request_queue
*q
, bool nowait
)
784 if (percpu_ref_tryget_live(&q
->q_usage_counter
))
791 * read pair of barrier in blk_freeze_queue_start(),
792 * we need to order reading __PERCPU_REF_DEAD flag of
793 * .q_usage_counter and reading .mq_freeze_depth or
794 * queue dying flag, otherwise the following wait may
795 * never return if the two reads are reordered.
799 ret
= wait_event_interruptible(q
->mq_freeze_wq
,
800 !atomic_read(&q
->mq_freeze_depth
) ||
802 if (blk_queue_dying(q
))
809 void blk_queue_exit(struct request_queue
*q
)
811 percpu_ref_put(&q
->q_usage_counter
);
814 static void blk_queue_usage_counter_release(struct percpu_ref
*ref
)
816 struct request_queue
*q
=
817 container_of(ref
, struct request_queue
, q_usage_counter
);
819 wake_up_all(&q
->mq_freeze_wq
);
822 static void blk_rq_timed_out_timer(unsigned long data
)
824 struct request_queue
*q
= (struct request_queue
*)data
;
826 kblockd_schedule_work(&q
->timeout_work
);
829 struct request_queue
*blk_alloc_queue_node(gfp_t gfp_mask
, int node_id
)
831 struct request_queue
*q
;
833 q
= kmem_cache_alloc_node(blk_requestq_cachep
,
834 gfp_mask
| __GFP_ZERO
, node_id
);
838 q
->id
= ida_simple_get(&blk_queue_ida
, 0, 0, gfp_mask
);
842 q
->bio_split
= bioset_create(BIO_POOL_SIZE
, 0, BIOSET_NEED_BVECS
);
846 q
->backing_dev_info
= bdi_alloc_node(gfp_mask
, node_id
);
847 if (!q
->backing_dev_info
)
850 q
->stats
= blk_alloc_queue_stats();
854 q
->backing_dev_info
->ra_pages
=
855 (VM_MAX_READAHEAD
* 1024) / PAGE_SIZE
;
856 q
->backing_dev_info
->capabilities
= BDI_CAP_CGROUP_WRITEBACK
;
857 q
->backing_dev_info
->name
= "block";
860 setup_timer(&q
->backing_dev_info
->laptop_mode_wb_timer
,
861 laptop_mode_timer_fn
, (unsigned long) q
);
862 setup_timer(&q
->timeout
, blk_rq_timed_out_timer
, (unsigned long) q
);
863 INIT_WORK(&q
->timeout_work
, NULL
);
864 INIT_LIST_HEAD(&q
->queue_head
);
865 INIT_LIST_HEAD(&q
->timeout_list
);
866 INIT_LIST_HEAD(&q
->icq_list
);
867 #ifdef CONFIG_BLK_CGROUP
868 INIT_LIST_HEAD(&q
->blkg_list
);
870 INIT_DELAYED_WORK(&q
->delay_work
, blk_delay_work
);
872 kobject_init(&q
->kobj
, &blk_queue_ktype
);
874 #ifdef CONFIG_BLK_DEV_IO_TRACE
875 mutex_init(&q
->blk_trace_mutex
);
877 mutex_init(&q
->sysfs_lock
);
878 spin_lock_init(&q
->__queue_lock
);
881 * By default initialize queue_lock to internal lock and driver can
882 * override it later if need be.
884 q
->queue_lock
= &q
->__queue_lock
;
887 * A queue starts its life with bypass turned on to avoid
888 * unnecessary bypass on/off overhead and nasty surprises during
889 * init. The initial bypass will be finished when the queue is
890 * registered by blk_register_queue().
893 __set_bit(QUEUE_FLAG_BYPASS
, &q
->queue_flags
);
895 init_waitqueue_head(&q
->mq_freeze_wq
);
898 * Init percpu_ref in atomic mode so that it's faster to shutdown.
899 * See blk_register_queue() for details.
901 if (percpu_ref_init(&q
->q_usage_counter
,
902 blk_queue_usage_counter_release
,
903 PERCPU_REF_INIT_ATOMIC
, GFP_KERNEL
))
906 if (blkcg_init_queue(q
))
912 percpu_ref_exit(&q
->q_usage_counter
);
914 blk_free_queue_stats(q
->stats
);
916 bdi_put(q
->backing_dev_info
);
918 bioset_free(q
->bio_split
);
920 ida_simple_remove(&blk_queue_ida
, q
->id
);
922 kmem_cache_free(blk_requestq_cachep
, q
);
925 EXPORT_SYMBOL(blk_alloc_queue_node
);
928 * blk_init_queue - prepare a request queue for use with a block device
929 * @rfn: The function to be called to process requests that have been
930 * placed on the queue.
931 * @lock: Request queue spin lock
934 * If a block device wishes to use the standard request handling procedures,
935 * which sorts requests and coalesces adjacent requests, then it must
936 * call blk_init_queue(). The function @rfn will be called when there
937 * are requests on the queue that need to be processed. If the device
938 * supports plugging, then @rfn may not be called immediately when requests
939 * are available on the queue, but may be called at some time later instead.
940 * Plugged queues are generally unplugged when a buffer belonging to one
941 * of the requests on the queue is needed, or due to memory pressure.
943 * @rfn is not required, or even expected, to remove all requests off the
944 * queue, but only as many as it can handle at a time. If it does leave
945 * requests on the queue, it is responsible for arranging that the requests
946 * get dealt with eventually.
948 * The queue spin lock must be held while manipulating the requests on the
949 * request queue; this lock will be taken also from interrupt context, so irq
950 * disabling is needed for it.
952 * Function returns a pointer to the initialized request queue, or %NULL if
956 * blk_init_queue() must be paired with a blk_cleanup_queue() call
957 * when the block device is deactivated (such as at module unload).
960 struct request_queue
*blk_init_queue(request_fn_proc
*rfn
, spinlock_t
*lock
)
962 return blk_init_queue_node(rfn
, lock
, NUMA_NO_NODE
);
964 EXPORT_SYMBOL(blk_init_queue
);
966 struct request_queue
*
967 blk_init_queue_node(request_fn_proc
*rfn
, spinlock_t
*lock
, int node_id
)
969 struct request_queue
*q
;
971 q
= blk_alloc_queue_node(GFP_KERNEL
, node_id
);
977 q
->queue_lock
= lock
;
978 if (blk_init_allocated_queue(q
) < 0) {
979 blk_cleanup_queue(q
);
985 EXPORT_SYMBOL(blk_init_queue_node
);
987 static blk_qc_t
blk_queue_bio(struct request_queue
*q
, struct bio
*bio
);
990 int blk_init_allocated_queue(struct request_queue
*q
)
992 WARN_ON_ONCE(q
->mq_ops
);
994 q
->fq
= blk_alloc_flush_queue(q
, NUMA_NO_NODE
, q
->cmd_size
);
998 if (q
->init_rq_fn
&& q
->init_rq_fn(q
, q
->fq
->flush_rq
, GFP_KERNEL
))
999 goto out_free_flush_queue
;
1001 if (blk_init_rl(&q
->root_rl
, q
, GFP_KERNEL
))
1002 goto out_exit_flush_rq
;
1004 INIT_WORK(&q
->timeout_work
, blk_timeout_work
);
1005 q
->queue_flags
|= QUEUE_FLAG_DEFAULT
;
1008 * This also sets hw/phys segments, boundary and size
1010 blk_queue_make_request(q
, blk_queue_bio
);
1012 q
->sg_reserved_size
= INT_MAX
;
1014 /* Protect q->elevator from elevator_change */
1015 mutex_lock(&q
->sysfs_lock
);
1018 if (elevator_init(q
, NULL
)) {
1019 mutex_unlock(&q
->sysfs_lock
);
1020 goto out_exit_flush_rq
;
1023 mutex_unlock(&q
->sysfs_lock
);
1028 q
->exit_rq_fn(q
, q
->fq
->flush_rq
);
1029 out_free_flush_queue
:
1030 blk_free_flush_queue(q
->fq
);
1033 EXPORT_SYMBOL(blk_init_allocated_queue
);
1035 bool blk_get_queue(struct request_queue
*q
)
1037 if (likely(!blk_queue_dying(q
))) {
1044 EXPORT_SYMBOL(blk_get_queue
);
1046 static inline void blk_free_request(struct request_list
*rl
, struct request
*rq
)
1048 if (rq
->rq_flags
& RQF_ELVPRIV
) {
1049 elv_put_request(rl
->q
, rq
);
1051 put_io_context(rq
->elv
.icq
->ioc
);
1054 mempool_free(rq
, rl
->rq_pool
);
1058 * ioc_batching returns true if the ioc is a valid batching request and
1059 * should be given priority access to a request.
1061 static inline int ioc_batching(struct request_queue
*q
, struct io_context
*ioc
)
1067 * Make sure the process is able to allocate at least 1 request
1068 * even if the batch times out, otherwise we could theoretically
1071 return ioc
->nr_batch_requests
== q
->nr_batching
||
1072 (ioc
->nr_batch_requests
> 0
1073 && time_before(jiffies
, ioc
->last_waited
+ BLK_BATCH_TIME
));
1077 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
1078 * will cause the process to be a "batcher" on all queues in the system. This
1079 * is the behaviour we want though - once it gets a wakeup it should be given
1082 static void ioc_set_batching(struct request_queue
*q
, struct io_context
*ioc
)
1084 if (!ioc
|| ioc_batching(q
, ioc
))
1087 ioc
->nr_batch_requests
= q
->nr_batching
;
1088 ioc
->last_waited
= jiffies
;
1091 static void __freed_request(struct request_list
*rl
, int sync
)
1093 struct request_queue
*q
= rl
->q
;
1095 if (rl
->count
[sync
] < queue_congestion_off_threshold(q
))
1096 blk_clear_congested(rl
, sync
);
1098 if (rl
->count
[sync
] + 1 <= q
->nr_requests
) {
1099 if (waitqueue_active(&rl
->wait
[sync
]))
1100 wake_up(&rl
->wait
[sync
]);
1102 blk_clear_rl_full(rl
, sync
);
1107 * A request has just been released. Account for it, update the full and
1108 * congestion status, wake up any waiters. Called under q->queue_lock.
1110 static void freed_request(struct request_list
*rl
, bool sync
,
1111 req_flags_t rq_flags
)
1113 struct request_queue
*q
= rl
->q
;
1117 if (rq_flags
& RQF_ELVPRIV
)
1118 q
->nr_rqs_elvpriv
--;
1120 __freed_request(rl
, sync
);
1122 if (unlikely(rl
->starved
[sync
^ 1]))
1123 __freed_request(rl
, sync
^ 1);
1126 int blk_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
1128 struct request_list
*rl
;
1129 int on_thresh
, off_thresh
;
1131 WARN_ON_ONCE(q
->mq_ops
);
1133 spin_lock_irq(q
->queue_lock
);
1134 q
->nr_requests
= nr
;
1135 blk_queue_congestion_threshold(q
);
1136 on_thresh
= queue_congestion_on_threshold(q
);
1137 off_thresh
= queue_congestion_off_threshold(q
);
1139 blk_queue_for_each_rl(rl
, q
) {
1140 if (rl
->count
[BLK_RW_SYNC
] >= on_thresh
)
1141 blk_set_congested(rl
, BLK_RW_SYNC
);
1142 else if (rl
->count
[BLK_RW_SYNC
] < off_thresh
)
1143 blk_clear_congested(rl
, BLK_RW_SYNC
);
1145 if (rl
->count
[BLK_RW_ASYNC
] >= on_thresh
)
1146 blk_set_congested(rl
, BLK_RW_ASYNC
);
1147 else if (rl
->count
[BLK_RW_ASYNC
] < off_thresh
)
1148 blk_clear_congested(rl
, BLK_RW_ASYNC
);
1150 if (rl
->count
[BLK_RW_SYNC
] >= q
->nr_requests
) {
1151 blk_set_rl_full(rl
, BLK_RW_SYNC
);
1153 blk_clear_rl_full(rl
, BLK_RW_SYNC
);
1154 wake_up(&rl
->wait
[BLK_RW_SYNC
]);
1157 if (rl
->count
[BLK_RW_ASYNC
] >= q
->nr_requests
) {
1158 blk_set_rl_full(rl
, BLK_RW_ASYNC
);
1160 blk_clear_rl_full(rl
, BLK_RW_ASYNC
);
1161 wake_up(&rl
->wait
[BLK_RW_ASYNC
]);
1165 spin_unlock_irq(q
->queue_lock
);
1170 * __get_request - get a free request
1171 * @rl: request list to allocate from
1172 * @op: operation and flags
1173 * @bio: bio to allocate request for (can be %NULL)
1174 * @gfp_mask: allocation mask
1176 * Get a free request from @q. This function may fail under memory
1177 * pressure or if @q is dead.
1179 * Must be called with @q->queue_lock held and,
1180 * Returns ERR_PTR on failure, with @q->queue_lock held.
1181 * Returns request pointer on success, with @q->queue_lock *not held*.
1183 static struct request
*__get_request(struct request_list
*rl
, unsigned int op
,
1184 struct bio
*bio
, gfp_t gfp_mask
)
1186 struct request_queue
*q
= rl
->q
;
1188 struct elevator_type
*et
= q
->elevator
->type
;
1189 struct io_context
*ioc
= rq_ioc(bio
);
1190 struct io_cq
*icq
= NULL
;
1191 const bool is_sync
= op_is_sync(op
);
1193 req_flags_t rq_flags
= RQF_ALLOCED
;
1195 lockdep_assert_held(q
->queue_lock
);
1197 if (unlikely(blk_queue_dying(q
)))
1198 return ERR_PTR(-ENODEV
);
1200 may_queue
= elv_may_queue(q
, op
);
1201 if (may_queue
== ELV_MQUEUE_NO
)
1204 if (rl
->count
[is_sync
]+1 >= queue_congestion_on_threshold(q
)) {
1205 if (rl
->count
[is_sync
]+1 >= q
->nr_requests
) {
1207 * The queue will fill after this allocation, so set
1208 * it as full, and mark this process as "batching".
1209 * This process will be allowed to complete a batch of
1210 * requests, others will be blocked.
1212 if (!blk_rl_full(rl
, is_sync
)) {
1213 ioc_set_batching(q
, ioc
);
1214 blk_set_rl_full(rl
, is_sync
);
1216 if (may_queue
!= ELV_MQUEUE_MUST
1217 && !ioc_batching(q
, ioc
)) {
1219 * The queue is full and the allocating
1220 * process is not a "batcher", and not
1221 * exempted by the IO scheduler
1223 return ERR_PTR(-ENOMEM
);
1227 blk_set_congested(rl
, is_sync
);
1231 * Only allow batching queuers to allocate up to 50% over the defined
1232 * limit of requests, otherwise we could have thousands of requests
1233 * allocated with any setting of ->nr_requests
1235 if (rl
->count
[is_sync
] >= (3 * q
->nr_requests
/ 2))
1236 return ERR_PTR(-ENOMEM
);
1238 q
->nr_rqs
[is_sync
]++;
1239 rl
->count
[is_sync
]++;
1240 rl
->starved
[is_sync
] = 0;
1243 * Decide whether the new request will be managed by elevator. If
1244 * so, mark @rq_flags and increment elvpriv. Non-zero elvpriv will
1245 * prevent the current elevator from being destroyed until the new
1246 * request is freed. This guarantees icq's won't be destroyed and
1247 * makes creating new ones safe.
1249 * Flush requests do not use the elevator so skip initialization.
1250 * This allows a request to share the flush and elevator data.
1252 * Also, lookup icq while holding queue_lock. If it doesn't exist,
1253 * it will be created after releasing queue_lock.
1255 if (!op_is_flush(op
) && !blk_queue_bypass(q
)) {
1256 rq_flags
|= RQF_ELVPRIV
;
1257 q
->nr_rqs_elvpriv
++;
1258 if (et
->icq_cache
&& ioc
)
1259 icq
= ioc_lookup_icq(ioc
, q
);
1262 if (blk_queue_io_stat(q
))
1263 rq_flags
|= RQF_IO_STAT
;
1264 spin_unlock_irq(q
->queue_lock
);
1266 /* allocate and init request */
1267 rq
= mempool_alloc(rl
->rq_pool
, gfp_mask
);
1272 blk_rq_set_rl(rq
, rl
);
1274 rq
->rq_flags
= rq_flags
;
1277 if (rq_flags
& RQF_ELVPRIV
) {
1278 if (unlikely(et
->icq_cache
&& !icq
)) {
1280 icq
= ioc_create_icq(ioc
, q
, gfp_mask
);
1286 if (unlikely(elv_set_request(q
, rq
, bio
, gfp_mask
)))
1289 /* @rq->elv.icq holds io_context until @rq is freed */
1291 get_io_context(icq
->ioc
);
1295 * ioc may be NULL here, and ioc_batching will be false. That's
1296 * OK, if the queue is under the request limit then requests need
1297 * not count toward the nr_batch_requests limit. There will always
1298 * be some limit enforced by BLK_BATCH_TIME.
1300 if (ioc_batching(q
, ioc
))
1301 ioc
->nr_batch_requests
--;
1303 trace_block_getrq(q
, bio
, op
);
1308 * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed
1309 * and may fail indefinitely under memory pressure and thus
1310 * shouldn't stall IO. Treat this request as !elvpriv. This will
1311 * disturb iosched and blkcg but weird is bettern than dead.
1313 printk_ratelimited(KERN_WARNING
"%s: dev %s: request aux data allocation failed, iosched may be disturbed\n",
1314 __func__
, dev_name(q
->backing_dev_info
->dev
));
1316 rq
->rq_flags
&= ~RQF_ELVPRIV
;
1319 spin_lock_irq(q
->queue_lock
);
1320 q
->nr_rqs_elvpriv
--;
1321 spin_unlock_irq(q
->queue_lock
);
1326 * Allocation failed presumably due to memory. Undo anything we
1327 * might have messed up.
1329 * Allocating task should really be put onto the front of the wait
1330 * queue, but this is pretty rare.
1332 spin_lock_irq(q
->queue_lock
);
1333 freed_request(rl
, is_sync
, rq_flags
);
1336 * in the very unlikely event that allocation failed and no
1337 * requests for this direction was pending, mark us starved so that
1338 * freeing of a request in the other direction will notice
1339 * us. another possible fix would be to split the rq mempool into
1343 if (unlikely(rl
->count
[is_sync
] == 0))
1344 rl
->starved
[is_sync
] = 1;
1345 return ERR_PTR(-ENOMEM
);
1349 * get_request - get a free request
1350 * @q: request_queue to allocate request from
1351 * @op: operation and flags
1352 * @bio: bio to allocate request for (can be %NULL)
1353 * @gfp_mask: allocation mask
1355 * Get a free request from @q. If %__GFP_DIRECT_RECLAIM is set in @gfp_mask,
1356 * this function keeps retrying under memory pressure and fails iff @q is dead.
1358 * Must be called with @q->queue_lock held and,
1359 * Returns ERR_PTR on failure, with @q->queue_lock held.
1360 * Returns request pointer on success, with @q->queue_lock *not held*.
1362 static struct request
*get_request(struct request_queue
*q
, unsigned int op
,
1363 struct bio
*bio
, gfp_t gfp_mask
)
1365 const bool is_sync
= op_is_sync(op
);
1367 struct request_list
*rl
;
1370 lockdep_assert_held(q
->queue_lock
);
1371 WARN_ON_ONCE(q
->mq_ops
);
1373 rl
= blk_get_rl(q
, bio
); /* transferred to @rq on success */
1375 rq
= __get_request(rl
, op
, bio
, gfp_mask
);
1379 if (op
& REQ_NOWAIT
) {
1381 return ERR_PTR(-EAGAIN
);
1384 if (!gfpflags_allow_blocking(gfp_mask
) || unlikely(blk_queue_dying(q
))) {
1389 /* wait on @rl and retry */
1390 prepare_to_wait_exclusive(&rl
->wait
[is_sync
], &wait
,
1391 TASK_UNINTERRUPTIBLE
);
1393 trace_block_sleeprq(q
, bio
, op
);
1395 spin_unlock_irq(q
->queue_lock
);
1399 * After sleeping, we become a "batching" process and will be able
1400 * to allocate at least one request, and up to a big batch of them
1401 * for a small period time. See ioc_batching, ioc_set_batching
1403 ioc_set_batching(q
, current
->io_context
);
1405 spin_lock_irq(q
->queue_lock
);
1406 finish_wait(&rl
->wait
[is_sync
], &wait
);
1411 static struct request
*blk_old_get_request(struct request_queue
*q
,
1412 unsigned int op
, gfp_t gfp_mask
)
1416 WARN_ON_ONCE(q
->mq_ops
);
1418 /* create ioc upfront */
1419 create_io_context(gfp_mask
, q
->node
);
1421 spin_lock_irq(q
->queue_lock
);
1422 rq
= get_request(q
, op
, NULL
, gfp_mask
);
1424 spin_unlock_irq(q
->queue_lock
);
1428 /* q->queue_lock is unlocked at this point */
1430 rq
->__sector
= (sector_t
) -1;
1431 rq
->bio
= rq
->biotail
= NULL
;
1435 struct request
*blk_get_request(struct request_queue
*q
, unsigned int op
,
1438 struct request
*req
;
1441 req
= blk_mq_alloc_request(q
, op
,
1442 (gfp_mask
& __GFP_DIRECT_RECLAIM
) ?
1443 0 : BLK_MQ_REQ_NOWAIT
);
1444 if (!IS_ERR(req
) && q
->mq_ops
->initialize_rq_fn
)
1445 q
->mq_ops
->initialize_rq_fn(req
);
1447 req
= blk_old_get_request(q
, op
, gfp_mask
);
1448 if (!IS_ERR(req
) && q
->initialize_rq_fn
)
1449 q
->initialize_rq_fn(req
);
1454 EXPORT_SYMBOL(blk_get_request
);
1457 * blk_requeue_request - put a request back on queue
1458 * @q: request queue where request should be inserted
1459 * @rq: request to be inserted
1462 * Drivers often keep queueing requests until the hardware cannot accept
1463 * more, when that condition happens we need to put the request back
1464 * on the queue. Must be called with queue lock held.
1466 void blk_requeue_request(struct request_queue
*q
, struct request
*rq
)
1468 lockdep_assert_held(q
->queue_lock
);
1469 WARN_ON_ONCE(q
->mq_ops
);
1471 blk_delete_timer(rq
);
1472 blk_clear_rq_complete(rq
);
1473 trace_block_rq_requeue(q
, rq
);
1474 wbt_requeue(q
->rq_wb
, &rq
->issue_stat
);
1476 if (rq
->rq_flags
& RQF_QUEUED
)
1477 blk_queue_end_tag(q
, rq
);
1479 BUG_ON(blk_queued_rq(rq
));
1481 elv_requeue_request(q
, rq
);
1483 EXPORT_SYMBOL(blk_requeue_request
);
1485 static void add_acct_request(struct request_queue
*q
, struct request
*rq
,
1488 blk_account_io_start(rq
, true);
1489 __elv_add_request(q
, rq
, where
);
1492 static void part_round_stats_single(struct request_queue
*q
, int cpu
,
1493 struct hd_struct
*part
, unsigned long now
,
1494 unsigned int inflight
)
1497 __part_stat_add(cpu
, part
, time_in_queue
,
1498 inflight
* (now
- part
->stamp
));
1499 __part_stat_add(cpu
, part
, io_ticks
, (now
- part
->stamp
));
1505 * part_round_stats() - Round off the performance stats on a struct disk_stats.
1506 * @q: target block queue
1507 * @cpu: cpu number for stats access
1508 * @part: target partition
1510 * The average IO queue length and utilisation statistics are maintained
1511 * by observing the current state of the queue length and the amount of
1512 * time it has been in this state for.
1514 * Normally, that accounting is done on IO completion, but that can result
1515 * in more than a second's worth of IO being accounted for within any one
1516 * second, leading to >100% utilisation. To deal with that, we call this
1517 * function to do a round-off before returning the results when reading
1518 * /proc/diskstats. This accounts immediately for all queue usage up to
1519 * the current jiffies and restarts the counters again.
1521 void part_round_stats(struct request_queue
*q
, int cpu
, struct hd_struct
*part
)
1523 struct hd_struct
*part2
= NULL
;
1524 unsigned long now
= jiffies
;
1525 unsigned int inflight
[2];
1528 if (part
->stamp
!= now
)
1532 part2
= &part_to_disk(part
)->part0
;
1533 if (part2
->stamp
!= now
)
1540 part_in_flight(q
, part
, inflight
);
1543 part_round_stats_single(q
, cpu
, part2
, now
, inflight
[1]);
1545 part_round_stats_single(q
, cpu
, part
, now
, inflight
[0]);
1547 EXPORT_SYMBOL_GPL(part_round_stats
);
1550 static void blk_pm_put_request(struct request
*rq
)
1552 if (rq
->q
->dev
&& !(rq
->rq_flags
& RQF_PM
) && !--rq
->q
->nr_pending
)
1553 pm_runtime_mark_last_busy(rq
->q
->dev
);
1556 static inline void blk_pm_put_request(struct request
*rq
) {}
1559 void __blk_put_request(struct request_queue
*q
, struct request
*req
)
1561 req_flags_t rq_flags
= req
->rq_flags
;
1567 blk_mq_free_request(req
);
1571 lockdep_assert_held(q
->queue_lock
);
1573 blk_pm_put_request(req
);
1575 elv_completed_request(q
, req
);
1577 /* this is a bio leak */
1578 WARN_ON(req
->bio
!= NULL
);
1580 wbt_done(q
->rq_wb
, &req
->issue_stat
);
1583 * Request may not have originated from ll_rw_blk. if not,
1584 * it didn't come out of our reserved rq pools
1586 if (rq_flags
& RQF_ALLOCED
) {
1587 struct request_list
*rl
= blk_rq_rl(req
);
1588 bool sync
= op_is_sync(req
->cmd_flags
);
1590 BUG_ON(!list_empty(&req
->queuelist
));
1591 BUG_ON(ELV_ON_HASH(req
));
1593 blk_free_request(rl
, req
);
1594 freed_request(rl
, sync
, rq_flags
);
1598 EXPORT_SYMBOL_GPL(__blk_put_request
);
1600 void blk_put_request(struct request
*req
)
1602 struct request_queue
*q
= req
->q
;
1605 blk_mq_free_request(req
);
1607 unsigned long flags
;
1609 spin_lock_irqsave(q
->queue_lock
, flags
);
1610 __blk_put_request(q
, req
);
1611 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1614 EXPORT_SYMBOL(blk_put_request
);
1616 bool bio_attempt_back_merge(struct request_queue
*q
, struct request
*req
,
1619 const int ff
= bio
->bi_opf
& REQ_FAILFAST_MASK
;
1621 if (!ll_back_merge_fn(q
, req
, bio
))
1624 trace_block_bio_backmerge(q
, req
, bio
);
1626 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
1627 blk_rq_set_mixed_merge(req
);
1629 req
->biotail
->bi_next
= bio
;
1631 req
->__data_len
+= bio
->bi_iter
.bi_size
;
1632 req
->ioprio
= ioprio_best(req
->ioprio
, bio_prio(bio
));
1634 blk_account_io_start(req
, false);
1638 bool bio_attempt_front_merge(struct request_queue
*q
, struct request
*req
,
1641 const int ff
= bio
->bi_opf
& REQ_FAILFAST_MASK
;
1643 if (!ll_front_merge_fn(q
, req
, bio
))
1646 trace_block_bio_frontmerge(q
, req
, bio
);
1648 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
1649 blk_rq_set_mixed_merge(req
);
1651 bio
->bi_next
= req
->bio
;
1654 req
->__sector
= bio
->bi_iter
.bi_sector
;
1655 req
->__data_len
+= bio
->bi_iter
.bi_size
;
1656 req
->ioprio
= ioprio_best(req
->ioprio
, bio_prio(bio
));
1658 blk_account_io_start(req
, false);
1662 bool bio_attempt_discard_merge(struct request_queue
*q
, struct request
*req
,
1665 unsigned short segments
= blk_rq_nr_discard_segments(req
);
1667 if (segments
>= queue_max_discard_segments(q
))
1669 if (blk_rq_sectors(req
) + bio_sectors(bio
) >
1670 blk_rq_get_max_sectors(req
, blk_rq_pos(req
)))
1673 req
->biotail
->bi_next
= bio
;
1675 req
->__data_len
+= bio
->bi_iter
.bi_size
;
1676 req
->ioprio
= ioprio_best(req
->ioprio
, bio_prio(bio
));
1677 req
->nr_phys_segments
= segments
+ 1;
1679 blk_account_io_start(req
, false);
1682 req_set_nomerge(q
, req
);
1687 * blk_attempt_plug_merge - try to merge with %current's plugged list
1688 * @q: request_queue new bio is being queued at
1689 * @bio: new bio being queued
1690 * @request_count: out parameter for number of traversed plugged requests
1691 * @same_queue_rq: pointer to &struct request that gets filled in when
1692 * another request associated with @q is found on the plug list
1693 * (optional, may be %NULL)
1695 * Determine whether @bio being queued on @q can be merged with a request
1696 * on %current's plugged list. Returns %true if merge was successful,
1699 * Plugging coalesces IOs from the same issuer for the same purpose without
1700 * going through @q->queue_lock. As such it's more of an issuing mechanism
1701 * than scheduling, and the request, while may have elvpriv data, is not
1702 * added on the elevator at this point. In addition, we don't have
1703 * reliable access to the elevator outside queue lock. Only check basic
1704 * merging parameters without querying the elevator.
1706 * Caller must ensure !blk_queue_nomerges(q) beforehand.
1708 bool blk_attempt_plug_merge(struct request_queue
*q
, struct bio
*bio
,
1709 unsigned int *request_count
,
1710 struct request
**same_queue_rq
)
1712 struct blk_plug
*plug
;
1714 struct list_head
*plug_list
;
1716 plug
= current
->plug
;
1722 plug_list
= &plug
->mq_list
;
1724 plug_list
= &plug
->list
;
1726 list_for_each_entry_reverse(rq
, plug_list
, queuelist
) {
1727 bool merged
= false;
1732 * Only blk-mq multiple hardware queues case checks the
1733 * rq in the same queue, there should be only one such
1737 *same_queue_rq
= rq
;
1740 if (rq
->q
!= q
|| !blk_rq_merge_ok(rq
, bio
))
1743 switch (blk_try_merge(rq
, bio
)) {
1744 case ELEVATOR_BACK_MERGE
:
1745 merged
= bio_attempt_back_merge(q
, rq
, bio
);
1747 case ELEVATOR_FRONT_MERGE
:
1748 merged
= bio_attempt_front_merge(q
, rq
, bio
);
1750 case ELEVATOR_DISCARD_MERGE
:
1751 merged
= bio_attempt_discard_merge(q
, rq
, bio
);
1764 unsigned int blk_plug_queued_count(struct request_queue
*q
)
1766 struct blk_plug
*plug
;
1768 struct list_head
*plug_list
;
1769 unsigned int ret
= 0;
1771 plug
= current
->plug
;
1776 plug_list
= &plug
->mq_list
;
1778 plug_list
= &plug
->list
;
1780 list_for_each_entry(rq
, plug_list
, queuelist
) {
1788 void blk_init_request_from_bio(struct request
*req
, struct bio
*bio
)
1790 struct io_context
*ioc
= rq_ioc(bio
);
1792 if (bio
->bi_opf
& REQ_RAHEAD
)
1793 req
->cmd_flags
|= REQ_FAILFAST_MASK
;
1795 req
->__sector
= bio
->bi_iter
.bi_sector
;
1796 if (ioprio_valid(bio_prio(bio
)))
1797 req
->ioprio
= bio_prio(bio
);
1799 req
->ioprio
= ioc
->ioprio
;
1801 req
->ioprio
= IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE
, 0);
1802 req
->write_hint
= bio
->bi_write_hint
;
1803 blk_rq_bio_prep(req
->q
, req
, bio
);
1805 EXPORT_SYMBOL_GPL(blk_init_request_from_bio
);
1807 static blk_qc_t
blk_queue_bio(struct request_queue
*q
, struct bio
*bio
)
1809 struct blk_plug
*plug
;
1810 int where
= ELEVATOR_INSERT_SORT
;
1811 struct request
*req
, *free
;
1812 unsigned int request_count
= 0;
1813 unsigned int wb_acct
;
1816 * low level driver can indicate that it wants pages above a
1817 * certain limit bounced to low memory (ie for highmem, or even
1818 * ISA dma in theory)
1820 blk_queue_bounce(q
, &bio
);
1822 blk_queue_split(q
, &bio
);
1824 if (!bio_integrity_prep(bio
))
1825 return BLK_QC_T_NONE
;
1827 if (op_is_flush(bio
->bi_opf
)) {
1828 spin_lock_irq(q
->queue_lock
);
1829 where
= ELEVATOR_INSERT_FLUSH
;
1834 * Check if we can merge with the plugged list before grabbing
1837 if (!blk_queue_nomerges(q
)) {
1838 if (blk_attempt_plug_merge(q
, bio
, &request_count
, NULL
))
1839 return BLK_QC_T_NONE
;
1841 request_count
= blk_plug_queued_count(q
);
1843 spin_lock_irq(q
->queue_lock
);
1845 switch (elv_merge(q
, &req
, bio
)) {
1846 case ELEVATOR_BACK_MERGE
:
1847 if (!bio_attempt_back_merge(q
, req
, bio
))
1849 elv_bio_merged(q
, req
, bio
);
1850 free
= attempt_back_merge(q
, req
);
1852 __blk_put_request(q
, free
);
1854 elv_merged_request(q
, req
, ELEVATOR_BACK_MERGE
);
1856 case ELEVATOR_FRONT_MERGE
:
1857 if (!bio_attempt_front_merge(q
, req
, bio
))
1859 elv_bio_merged(q
, req
, bio
);
1860 free
= attempt_front_merge(q
, req
);
1862 __blk_put_request(q
, free
);
1864 elv_merged_request(q
, req
, ELEVATOR_FRONT_MERGE
);
1871 wb_acct
= wbt_wait(q
->rq_wb
, bio
, q
->queue_lock
);
1874 * Grab a free request. This is might sleep but can not fail.
1875 * Returns with the queue unlocked.
1877 req
= get_request(q
, bio
->bi_opf
, bio
, GFP_NOIO
);
1879 __wbt_done(q
->rq_wb
, wb_acct
);
1880 if (PTR_ERR(req
) == -ENOMEM
)
1881 bio
->bi_status
= BLK_STS_RESOURCE
;
1883 bio
->bi_status
= BLK_STS_IOERR
;
1888 wbt_track(&req
->issue_stat
, wb_acct
);
1891 * After dropping the lock and possibly sleeping here, our request
1892 * may now be mergeable after it had proven unmergeable (above).
1893 * We don't worry about that case for efficiency. It won't happen
1894 * often, and the elevators are able to handle it.
1896 blk_init_request_from_bio(req
, bio
);
1898 if (test_bit(QUEUE_FLAG_SAME_COMP
, &q
->queue_flags
))
1899 req
->cpu
= raw_smp_processor_id();
1901 plug
= current
->plug
;
1904 * If this is the first request added after a plug, fire
1907 * @request_count may become stale because of schedule
1908 * out, so check plug list again.
1910 if (!request_count
|| list_empty(&plug
->list
))
1911 trace_block_plug(q
);
1913 struct request
*last
= list_entry_rq(plug
->list
.prev
);
1914 if (request_count
>= BLK_MAX_REQUEST_COUNT
||
1915 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
) {
1916 blk_flush_plug_list(plug
, false);
1917 trace_block_plug(q
);
1920 list_add_tail(&req
->queuelist
, &plug
->list
);
1921 blk_account_io_start(req
, true);
1923 spin_lock_irq(q
->queue_lock
);
1924 add_acct_request(q
, req
, where
);
1927 spin_unlock_irq(q
->queue_lock
);
1930 return BLK_QC_T_NONE
;
1933 static void handle_bad_sector(struct bio
*bio
)
1935 char b
[BDEVNAME_SIZE
];
1937 printk(KERN_INFO
"attempt to access beyond end of device\n");
1938 printk(KERN_INFO
"%s: rw=%d, want=%Lu, limit=%Lu\n",
1939 bio_devname(bio
, b
), bio
->bi_opf
,
1940 (unsigned long long)bio_end_sector(bio
),
1941 (long long)get_capacity(bio
->bi_disk
));
1944 #ifdef CONFIG_FAIL_MAKE_REQUEST
1946 static DECLARE_FAULT_ATTR(fail_make_request
);
1948 static int __init
setup_fail_make_request(char *str
)
1950 return setup_fault_attr(&fail_make_request
, str
);
1952 __setup("fail_make_request=", setup_fail_make_request
);
1954 static bool should_fail_request(struct hd_struct
*part
, unsigned int bytes
)
1956 return part
->make_it_fail
&& should_fail(&fail_make_request
, bytes
);
1959 static int __init
fail_make_request_debugfs(void)
1961 struct dentry
*dir
= fault_create_debugfs_attr("fail_make_request",
1962 NULL
, &fail_make_request
);
1964 return PTR_ERR_OR_ZERO(dir
);
1967 late_initcall(fail_make_request_debugfs
);
1969 #else /* CONFIG_FAIL_MAKE_REQUEST */
1971 static inline bool should_fail_request(struct hd_struct
*part
,
1977 #endif /* CONFIG_FAIL_MAKE_REQUEST */
1980 * Remap block n of partition p to block n+start(p) of the disk.
1982 static inline int blk_partition_remap(struct bio
*bio
)
1984 struct hd_struct
*p
;
1988 * Zone reset does not include bi_size so bio_sectors() is always 0.
1989 * Include a test for the reset op code and perform the remap if needed.
1991 if (!bio
->bi_partno
||
1992 (!bio_sectors(bio
) && bio_op(bio
) != REQ_OP_ZONE_RESET
))
1996 p
= __disk_get_part(bio
->bi_disk
, bio
->bi_partno
);
1997 if (likely(p
&& !should_fail_request(p
, bio
->bi_iter
.bi_size
))) {
1998 bio
->bi_iter
.bi_sector
+= p
->start_sect
;
2000 trace_block_bio_remap(bio
->bi_disk
->queue
, bio
, part_devt(p
),
2001 bio
->bi_iter
.bi_sector
- p
->start_sect
);
2003 printk("%s: fail for partition %d\n", __func__
, bio
->bi_partno
);
2012 * Check whether this bio extends beyond the end of the device.
2014 static inline int bio_check_eod(struct bio
*bio
, unsigned int nr_sectors
)
2021 /* Test device or partition size, when known. */
2022 maxsector
= get_capacity(bio
->bi_disk
);
2024 sector_t sector
= bio
->bi_iter
.bi_sector
;
2026 if (maxsector
< nr_sectors
|| maxsector
- nr_sectors
< sector
) {
2028 * This may well happen - the kernel calls bread()
2029 * without checking the size of the device, e.g., when
2030 * mounting a device.
2032 handle_bad_sector(bio
);
2040 static noinline_for_stack
bool
2041 generic_make_request_checks(struct bio
*bio
)
2043 struct request_queue
*q
;
2044 int nr_sectors
= bio_sectors(bio
);
2045 blk_status_t status
= BLK_STS_IOERR
;
2046 char b
[BDEVNAME_SIZE
];
2050 if (bio_check_eod(bio
, nr_sectors
))
2053 q
= bio
->bi_disk
->queue
;
2056 "generic_make_request: Trying to access "
2057 "nonexistent block-device %s (%Lu)\n",
2058 bio_devname(bio
, b
), (long long)bio
->bi_iter
.bi_sector
);
2063 * For a REQ_NOWAIT based request, return -EOPNOTSUPP
2064 * if queue is not a request based queue.
2067 if ((bio
->bi_opf
& REQ_NOWAIT
) && !queue_is_rq_based(q
))
2070 if (should_fail_request(&bio
->bi_disk
->part0
, bio
->bi_iter
.bi_size
))
2073 if (blk_partition_remap(bio
))
2076 if (bio_check_eod(bio
, nr_sectors
))
2080 * Filter flush bio's early so that make_request based
2081 * drivers without flush support don't have to worry
2084 if (op_is_flush(bio
->bi_opf
) &&
2085 !test_bit(QUEUE_FLAG_WC
, &q
->queue_flags
)) {
2086 bio
->bi_opf
&= ~(REQ_PREFLUSH
| REQ_FUA
);
2088 status
= BLK_STS_OK
;
2093 switch (bio_op(bio
)) {
2094 case REQ_OP_DISCARD
:
2095 if (!blk_queue_discard(q
))
2098 case REQ_OP_SECURE_ERASE
:
2099 if (!blk_queue_secure_erase(q
))
2102 case REQ_OP_WRITE_SAME
:
2103 if (!q
->limits
.max_write_same_sectors
)
2106 case REQ_OP_ZONE_REPORT
:
2107 case REQ_OP_ZONE_RESET
:
2108 if (!blk_queue_is_zoned(q
))
2111 case REQ_OP_WRITE_ZEROES
:
2112 if (!q
->limits
.max_write_zeroes_sectors
)
2120 * Various block parts want %current->io_context and lazy ioc
2121 * allocation ends up trading a lot of pain for a small amount of
2122 * memory. Just allocate it upfront. This may fail and block
2123 * layer knows how to live with it.
2125 create_io_context(GFP_ATOMIC
, q
->node
);
2127 if (!blkcg_bio_issue_check(q
, bio
))
2130 if (!bio_flagged(bio
, BIO_TRACE_COMPLETION
)) {
2131 trace_block_bio_queue(q
, bio
);
2132 /* Now that enqueuing has been traced, we need to trace
2133 * completion as well.
2135 bio_set_flag(bio
, BIO_TRACE_COMPLETION
);
2140 status
= BLK_STS_NOTSUPP
;
2142 bio
->bi_status
= status
;
2148 * generic_make_request - hand a buffer to its device driver for I/O
2149 * @bio: The bio describing the location in memory and on the device.
2151 * generic_make_request() is used to make I/O requests of block
2152 * devices. It is passed a &struct bio, which describes the I/O that needs
2155 * generic_make_request() does not return any status. The
2156 * success/failure status of the request, along with notification of
2157 * completion, is delivered asynchronously through the bio->bi_end_io
2158 * function described (one day) else where.
2160 * The caller of generic_make_request must make sure that bi_io_vec
2161 * are set to describe the memory buffer, and that bi_dev and bi_sector are
2162 * set to describe the device address, and the
2163 * bi_end_io and optionally bi_private are set to describe how
2164 * completion notification should be signaled.
2166 * generic_make_request and the drivers it calls may use bi_next if this
2167 * bio happens to be merged with someone else, and may resubmit the bio to
2168 * a lower device by calling into generic_make_request recursively, which
2169 * means the bio should NOT be touched after the call to ->make_request_fn.
2171 blk_qc_t
generic_make_request(struct bio
*bio
)
2174 * bio_list_on_stack[0] contains bios submitted by the current
2176 * bio_list_on_stack[1] contains bios that were submitted before
2177 * the current make_request_fn, but that haven't been processed
2180 struct bio_list bio_list_on_stack
[2];
2181 blk_qc_t ret
= BLK_QC_T_NONE
;
2183 if (!generic_make_request_checks(bio
))
2187 * We only want one ->make_request_fn to be active at a time, else
2188 * stack usage with stacked devices could be a problem. So use
2189 * current->bio_list to keep a list of requests submited by a
2190 * make_request_fn function. current->bio_list is also used as a
2191 * flag to say if generic_make_request is currently active in this
2192 * task or not. If it is NULL, then no make_request is active. If
2193 * it is non-NULL, then a make_request is active, and new requests
2194 * should be added at the tail
2196 if (current
->bio_list
) {
2197 bio_list_add(¤t
->bio_list
[0], bio
);
2201 /* following loop may be a bit non-obvious, and so deserves some
2203 * Before entering the loop, bio->bi_next is NULL (as all callers
2204 * ensure that) so we have a list with a single bio.
2205 * We pretend that we have just taken it off a longer list, so
2206 * we assign bio_list to a pointer to the bio_list_on_stack,
2207 * thus initialising the bio_list of new bios to be
2208 * added. ->make_request() may indeed add some more bios
2209 * through a recursive call to generic_make_request. If it
2210 * did, we find a non-NULL value in bio_list and re-enter the loop
2211 * from the top. In this case we really did just take the bio
2212 * of the top of the list (no pretending) and so remove it from
2213 * bio_list, and call into ->make_request() again.
2215 BUG_ON(bio
->bi_next
);
2216 bio_list_init(&bio_list_on_stack
[0]);
2217 current
->bio_list
= bio_list_on_stack
;
2219 struct request_queue
*q
= bio
->bi_disk
->queue
;
2221 if (likely(blk_queue_enter(q
, bio
->bi_opf
& REQ_NOWAIT
) == 0)) {
2222 struct bio_list lower
, same
;
2224 /* Create a fresh bio_list for all subordinate requests */
2225 bio_list_on_stack
[1] = bio_list_on_stack
[0];
2226 bio_list_init(&bio_list_on_stack
[0]);
2227 ret
= q
->make_request_fn(q
, bio
);
2231 /* sort new bios into those for a lower level
2232 * and those for the same level
2234 bio_list_init(&lower
);
2235 bio_list_init(&same
);
2236 while ((bio
= bio_list_pop(&bio_list_on_stack
[0])) != NULL
)
2237 if (q
== bio
->bi_disk
->queue
)
2238 bio_list_add(&same
, bio
);
2240 bio_list_add(&lower
, bio
);
2241 /* now assemble so we handle the lowest level first */
2242 bio_list_merge(&bio_list_on_stack
[0], &lower
);
2243 bio_list_merge(&bio_list_on_stack
[0], &same
);
2244 bio_list_merge(&bio_list_on_stack
[0], &bio_list_on_stack
[1]);
2246 if (unlikely(!blk_queue_dying(q
) &&
2247 (bio
->bi_opf
& REQ_NOWAIT
)))
2248 bio_wouldblock_error(bio
);
2252 bio
= bio_list_pop(&bio_list_on_stack
[0]);
2254 current
->bio_list
= NULL
; /* deactivate */
2259 EXPORT_SYMBOL(generic_make_request
);
2262 * submit_bio - submit a bio to the block device layer for I/O
2263 * @bio: The &struct bio which describes the I/O
2265 * submit_bio() is very similar in purpose to generic_make_request(), and
2266 * uses that function to do most of the work. Both are fairly rough
2267 * interfaces; @bio must be presetup and ready for I/O.
2270 blk_qc_t
submit_bio(struct bio
*bio
)
2273 * If it's a regular read/write or a barrier with data attached,
2274 * go through the normal accounting stuff before submission.
2276 if (bio_has_data(bio
)) {
2279 if (unlikely(bio_op(bio
) == REQ_OP_WRITE_SAME
))
2280 count
= queue_logical_block_size(bio
->bi_disk
->queue
) >> 9;
2282 count
= bio_sectors(bio
);
2284 if (op_is_write(bio_op(bio
))) {
2285 count_vm_events(PGPGOUT
, count
);
2287 task_io_account_read(bio
->bi_iter
.bi_size
);
2288 count_vm_events(PGPGIN
, count
);
2291 if (unlikely(block_dump
)) {
2292 char b
[BDEVNAME_SIZE
];
2293 printk(KERN_DEBUG
"%s(%d): %s block %Lu on %s (%u sectors)\n",
2294 current
->comm
, task_pid_nr(current
),
2295 op_is_write(bio_op(bio
)) ? "WRITE" : "READ",
2296 (unsigned long long)bio
->bi_iter
.bi_sector
,
2297 bio_devname(bio
, b
), count
);
2301 return generic_make_request(bio
);
2303 EXPORT_SYMBOL(submit_bio
);
2306 * blk_cloned_rq_check_limits - Helper function to check a cloned request
2307 * for new the queue limits
2309 * @rq: the request being checked
2312 * @rq may have been made based on weaker limitations of upper-level queues
2313 * in request stacking drivers, and it may violate the limitation of @q.
2314 * Since the block layer and the underlying device driver trust @rq
2315 * after it is inserted to @q, it should be checked against @q before
2316 * the insertion using this generic function.
2318 * Request stacking drivers like request-based dm may change the queue
2319 * limits when retrying requests on other queues. Those requests need
2320 * to be checked against the new queue limits again during dispatch.
2322 static int blk_cloned_rq_check_limits(struct request_queue
*q
,
2325 if (blk_rq_sectors(rq
) > blk_queue_get_max_sectors(q
, req_op(rq
))) {
2326 printk(KERN_ERR
"%s: over max size limit.\n", __func__
);
2331 * queue's settings related to segment counting like q->bounce_pfn
2332 * may differ from that of other stacking queues.
2333 * Recalculate it to check the request correctly on this queue's
2336 blk_recalc_rq_segments(rq
);
2337 if (rq
->nr_phys_segments
> queue_max_segments(q
)) {
2338 printk(KERN_ERR
"%s: over max segments limit.\n", __func__
);
2346 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
2347 * @q: the queue to submit the request
2348 * @rq: the request being queued
2350 blk_status_t
blk_insert_cloned_request(struct request_queue
*q
, struct request
*rq
)
2352 unsigned long flags
;
2353 int where
= ELEVATOR_INSERT_BACK
;
2355 if (blk_cloned_rq_check_limits(q
, rq
))
2356 return BLK_STS_IOERR
;
2359 should_fail_request(&rq
->rq_disk
->part0
, blk_rq_bytes(rq
)))
2360 return BLK_STS_IOERR
;
2363 if (blk_queue_io_stat(q
))
2364 blk_account_io_start(rq
, true);
2366 * Since we have a scheduler attached on the top device,
2367 * bypass a potential scheduler on the bottom device for
2370 blk_mq_request_bypass_insert(rq
);
2374 spin_lock_irqsave(q
->queue_lock
, flags
);
2375 if (unlikely(blk_queue_dying(q
))) {
2376 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2377 return BLK_STS_IOERR
;
2381 * Submitting request must be dequeued before calling this function
2382 * because it will be linked to another request_queue
2384 BUG_ON(blk_queued_rq(rq
));
2386 if (op_is_flush(rq
->cmd_flags
))
2387 where
= ELEVATOR_INSERT_FLUSH
;
2389 add_acct_request(q
, rq
, where
);
2390 if (where
== ELEVATOR_INSERT_FLUSH
)
2392 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2396 EXPORT_SYMBOL_GPL(blk_insert_cloned_request
);
2399 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
2400 * @rq: request to examine
2403 * A request could be merge of IOs which require different failure
2404 * handling. This function determines the number of bytes which
2405 * can be failed from the beginning of the request without
2406 * crossing into area which need to be retried further.
2409 * The number of bytes to fail.
2411 unsigned int blk_rq_err_bytes(const struct request
*rq
)
2413 unsigned int ff
= rq
->cmd_flags
& REQ_FAILFAST_MASK
;
2414 unsigned int bytes
= 0;
2417 if (!(rq
->rq_flags
& RQF_MIXED_MERGE
))
2418 return blk_rq_bytes(rq
);
2421 * Currently the only 'mixing' which can happen is between
2422 * different fastfail types. We can safely fail portions
2423 * which have all the failfast bits that the first one has -
2424 * the ones which are at least as eager to fail as the first
2427 for (bio
= rq
->bio
; bio
; bio
= bio
->bi_next
) {
2428 if ((bio
->bi_opf
& ff
) != ff
)
2430 bytes
+= bio
->bi_iter
.bi_size
;
2433 /* this could lead to infinite loop */
2434 BUG_ON(blk_rq_bytes(rq
) && !bytes
);
2437 EXPORT_SYMBOL_GPL(blk_rq_err_bytes
);
2439 void blk_account_io_completion(struct request
*req
, unsigned int bytes
)
2441 if (blk_do_io_stat(req
)) {
2442 const int rw
= rq_data_dir(req
);
2443 struct hd_struct
*part
;
2446 cpu
= part_stat_lock();
2448 part_stat_add(cpu
, part
, sectors
[rw
], bytes
>> 9);
2453 void blk_account_io_done(struct request
*req
)
2456 * Account IO completion. flush_rq isn't accounted as a
2457 * normal IO on queueing nor completion. Accounting the
2458 * containing request is enough.
2460 if (blk_do_io_stat(req
) && !(req
->rq_flags
& RQF_FLUSH_SEQ
)) {
2461 unsigned long duration
= jiffies
- req
->start_time
;
2462 const int rw
= rq_data_dir(req
);
2463 struct hd_struct
*part
;
2466 cpu
= part_stat_lock();
2469 part_stat_inc(cpu
, part
, ios
[rw
]);
2470 part_stat_add(cpu
, part
, ticks
[rw
], duration
);
2471 part_round_stats(req
->q
, cpu
, part
);
2472 part_dec_in_flight(req
->q
, part
, rw
);
2474 hd_struct_put(part
);
2481 * Don't process normal requests when queue is suspended
2482 * or in the process of suspending/resuming
2484 static struct request
*blk_pm_peek_request(struct request_queue
*q
,
2487 if (q
->dev
&& (q
->rpm_status
== RPM_SUSPENDED
||
2488 (q
->rpm_status
!= RPM_ACTIVE
&& !(rq
->rq_flags
& RQF_PM
))))
2494 static inline struct request
*blk_pm_peek_request(struct request_queue
*q
,
2501 void blk_account_io_start(struct request
*rq
, bool new_io
)
2503 struct hd_struct
*part
;
2504 int rw
= rq_data_dir(rq
);
2507 if (!blk_do_io_stat(rq
))
2510 cpu
= part_stat_lock();
2514 part_stat_inc(cpu
, part
, merges
[rw
]);
2516 part
= disk_map_sector_rcu(rq
->rq_disk
, blk_rq_pos(rq
));
2517 if (!hd_struct_try_get(part
)) {
2519 * The partition is already being removed,
2520 * the request will be accounted on the disk only
2522 * We take a reference on disk->part0 although that
2523 * partition will never be deleted, so we can treat
2524 * it as any other partition.
2526 part
= &rq
->rq_disk
->part0
;
2527 hd_struct_get(part
);
2529 part_round_stats(rq
->q
, cpu
, part
);
2530 part_inc_in_flight(rq
->q
, part
, rw
);
2538 * blk_peek_request - peek at the top of a request queue
2539 * @q: request queue to peek at
2542 * Return the request at the top of @q. The returned request
2543 * should be started using blk_start_request() before LLD starts
2547 * Pointer to the request at the top of @q if available. Null
2550 struct request
*blk_peek_request(struct request_queue
*q
)
2555 lockdep_assert_held(q
->queue_lock
);
2556 WARN_ON_ONCE(q
->mq_ops
);
2558 while ((rq
= __elv_next_request(q
)) != NULL
) {
2560 rq
= blk_pm_peek_request(q
, rq
);
2564 if (!(rq
->rq_flags
& RQF_STARTED
)) {
2566 * This is the first time the device driver
2567 * sees this request (possibly after
2568 * requeueing). Notify IO scheduler.
2570 if (rq
->rq_flags
& RQF_SORTED
)
2571 elv_activate_rq(q
, rq
);
2574 * just mark as started even if we don't start
2575 * it, a request that has been delayed should
2576 * not be passed by new incoming requests
2578 rq
->rq_flags
|= RQF_STARTED
;
2579 trace_block_rq_issue(q
, rq
);
2582 if (!q
->boundary_rq
|| q
->boundary_rq
== rq
) {
2583 q
->end_sector
= rq_end_sector(rq
);
2584 q
->boundary_rq
= NULL
;
2587 if (rq
->rq_flags
& RQF_DONTPREP
)
2590 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
2592 * make sure space for the drain appears we
2593 * know we can do this because max_hw_segments
2594 * has been adjusted to be one fewer than the
2597 rq
->nr_phys_segments
++;
2603 ret
= q
->prep_rq_fn(q
, rq
);
2604 if (ret
== BLKPREP_OK
) {
2606 } else if (ret
== BLKPREP_DEFER
) {
2608 * the request may have been (partially) prepped.
2609 * we need to keep this request in the front to
2610 * avoid resource deadlock. RQF_STARTED will
2611 * prevent other fs requests from passing this one.
2613 if (q
->dma_drain_size
&& blk_rq_bytes(rq
) &&
2614 !(rq
->rq_flags
& RQF_DONTPREP
)) {
2616 * remove the space for the drain we added
2617 * so that we don't add it again
2619 --rq
->nr_phys_segments
;
2624 } else if (ret
== BLKPREP_KILL
|| ret
== BLKPREP_INVALID
) {
2625 rq
->rq_flags
|= RQF_QUIET
;
2627 * Mark this request as started so we don't trigger
2628 * any debug logic in the end I/O path.
2630 blk_start_request(rq
);
2631 __blk_end_request_all(rq
, ret
== BLKPREP_INVALID
?
2632 BLK_STS_TARGET
: BLK_STS_IOERR
);
2634 printk(KERN_ERR
"%s: bad return=%d\n", __func__
, ret
);
2641 EXPORT_SYMBOL(blk_peek_request
);
2643 static void blk_dequeue_request(struct request
*rq
)
2645 struct request_queue
*q
= rq
->q
;
2647 BUG_ON(list_empty(&rq
->queuelist
));
2648 BUG_ON(ELV_ON_HASH(rq
));
2650 list_del_init(&rq
->queuelist
);
2653 * the time frame between a request being removed from the lists
2654 * and to it is freed is accounted as io that is in progress at
2657 if (blk_account_rq(rq
)) {
2658 q
->in_flight
[rq_is_sync(rq
)]++;
2659 set_io_start_time_ns(rq
);
2664 * blk_start_request - start request processing on the driver
2665 * @req: request to dequeue
2668 * Dequeue @req and start timeout timer on it. This hands off the
2669 * request to the driver.
2671 void blk_start_request(struct request
*req
)
2673 lockdep_assert_held(req
->q
->queue_lock
);
2674 WARN_ON_ONCE(req
->q
->mq_ops
);
2676 blk_dequeue_request(req
);
2678 if (test_bit(QUEUE_FLAG_STATS
, &req
->q
->queue_flags
)) {
2679 blk_stat_set_issue(&req
->issue_stat
, blk_rq_sectors(req
));
2680 req
->rq_flags
|= RQF_STATS
;
2681 wbt_issue(req
->q
->rq_wb
, &req
->issue_stat
);
2684 BUG_ON(test_bit(REQ_ATOM_COMPLETE
, &req
->atomic_flags
));
2687 EXPORT_SYMBOL(blk_start_request
);
2690 * blk_fetch_request - fetch a request from a request queue
2691 * @q: request queue to fetch a request from
2694 * Return the request at the top of @q. The request is started on
2695 * return and LLD can start processing it immediately.
2698 * Pointer to the request at the top of @q if available. Null
2701 struct request
*blk_fetch_request(struct request_queue
*q
)
2705 lockdep_assert_held(q
->queue_lock
);
2706 WARN_ON_ONCE(q
->mq_ops
);
2708 rq
= blk_peek_request(q
);
2710 blk_start_request(rq
);
2713 EXPORT_SYMBOL(blk_fetch_request
);
2716 * blk_update_request - Special helper function for request stacking drivers
2717 * @req: the request being processed
2718 * @error: block status code
2719 * @nr_bytes: number of bytes to complete @req
2722 * Ends I/O on a number of bytes attached to @req, but doesn't complete
2723 * the request structure even if @req doesn't have leftover.
2724 * If @req has leftover, sets it up for the next range of segments.
2726 * This special helper function is only for request stacking drivers
2727 * (e.g. request-based dm) so that they can handle partial completion.
2728 * Actual device drivers should use blk_end_request instead.
2730 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
2731 * %false return from this function.
2734 * %false - this request doesn't have any more data
2735 * %true - this request has more data
2737 bool blk_update_request(struct request
*req
, blk_status_t error
,
2738 unsigned int nr_bytes
)
2742 trace_block_rq_complete(req
, blk_status_to_errno(error
), nr_bytes
);
2747 if (unlikely(error
&& !blk_rq_is_passthrough(req
) &&
2748 !(req
->rq_flags
& RQF_QUIET
)))
2749 print_req_error(req
, error
);
2751 blk_account_io_completion(req
, nr_bytes
);
2755 struct bio
*bio
= req
->bio
;
2756 unsigned bio_bytes
= min(bio
->bi_iter
.bi_size
, nr_bytes
);
2758 if (bio_bytes
== bio
->bi_iter
.bi_size
)
2759 req
->bio
= bio
->bi_next
;
2761 /* Completion has already been traced */
2762 bio_clear_flag(bio
, BIO_TRACE_COMPLETION
);
2763 req_bio_endio(req
, bio
, bio_bytes
, error
);
2765 total_bytes
+= bio_bytes
;
2766 nr_bytes
-= bio_bytes
;
2777 * Reset counters so that the request stacking driver
2778 * can find how many bytes remain in the request
2781 req
->__data_len
= 0;
2785 req
->__data_len
-= total_bytes
;
2787 /* update sector only for requests with clear definition of sector */
2788 if (!blk_rq_is_passthrough(req
))
2789 req
->__sector
+= total_bytes
>> 9;
2791 /* mixed attributes always follow the first bio */
2792 if (req
->rq_flags
& RQF_MIXED_MERGE
) {
2793 req
->cmd_flags
&= ~REQ_FAILFAST_MASK
;
2794 req
->cmd_flags
|= req
->bio
->bi_opf
& REQ_FAILFAST_MASK
;
2797 if (!(req
->rq_flags
& RQF_SPECIAL_PAYLOAD
)) {
2799 * If total number of sectors is less than the first segment
2800 * size, something has gone terribly wrong.
2802 if (blk_rq_bytes(req
) < blk_rq_cur_bytes(req
)) {
2803 blk_dump_rq_flags(req
, "request botched");
2804 req
->__data_len
= blk_rq_cur_bytes(req
);
2807 /* recalculate the number of segments */
2808 blk_recalc_rq_segments(req
);
2813 EXPORT_SYMBOL_GPL(blk_update_request
);
2815 static bool blk_update_bidi_request(struct request
*rq
, blk_status_t error
,
2816 unsigned int nr_bytes
,
2817 unsigned int bidi_bytes
)
2819 if (blk_update_request(rq
, error
, nr_bytes
))
2822 /* Bidi request must be completed as a whole */
2823 if (unlikely(blk_bidi_rq(rq
)) &&
2824 blk_update_request(rq
->next_rq
, error
, bidi_bytes
))
2827 if (blk_queue_add_random(rq
->q
))
2828 add_disk_randomness(rq
->rq_disk
);
2834 * blk_unprep_request - unprepare a request
2837 * This function makes a request ready for complete resubmission (or
2838 * completion). It happens only after all error handling is complete,
2839 * so represents the appropriate moment to deallocate any resources
2840 * that were allocated to the request in the prep_rq_fn. The queue
2841 * lock is held when calling this.
2843 void blk_unprep_request(struct request
*req
)
2845 struct request_queue
*q
= req
->q
;
2847 req
->rq_flags
&= ~RQF_DONTPREP
;
2848 if (q
->unprep_rq_fn
)
2849 q
->unprep_rq_fn(q
, req
);
2851 EXPORT_SYMBOL_GPL(blk_unprep_request
);
2853 void blk_finish_request(struct request
*req
, blk_status_t error
)
2855 struct request_queue
*q
= req
->q
;
2857 lockdep_assert_held(req
->q
->queue_lock
);
2858 WARN_ON_ONCE(q
->mq_ops
);
2860 if (req
->rq_flags
& RQF_STATS
)
2863 if (req
->rq_flags
& RQF_QUEUED
)
2864 blk_queue_end_tag(q
, req
);
2866 BUG_ON(blk_queued_rq(req
));
2868 if (unlikely(laptop_mode
) && !blk_rq_is_passthrough(req
))
2869 laptop_io_completion(req
->q
->backing_dev_info
);
2871 blk_delete_timer(req
);
2873 if (req
->rq_flags
& RQF_DONTPREP
)
2874 blk_unprep_request(req
);
2876 blk_account_io_done(req
);
2879 wbt_done(req
->q
->rq_wb
, &req
->issue_stat
);
2880 req
->end_io(req
, error
);
2882 if (blk_bidi_rq(req
))
2883 __blk_put_request(req
->next_rq
->q
, req
->next_rq
);
2885 __blk_put_request(q
, req
);
2888 EXPORT_SYMBOL(blk_finish_request
);
2891 * blk_end_bidi_request - Complete a bidi request
2892 * @rq: the request to complete
2893 * @error: block status code
2894 * @nr_bytes: number of bytes to complete @rq
2895 * @bidi_bytes: number of bytes to complete @rq->next_rq
2898 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2899 * Drivers that supports bidi can safely call this member for any
2900 * type of request, bidi or uni. In the later case @bidi_bytes is
2904 * %false - we are done with this request
2905 * %true - still buffers pending for this request
2907 static bool blk_end_bidi_request(struct request
*rq
, blk_status_t error
,
2908 unsigned int nr_bytes
, unsigned int bidi_bytes
)
2910 struct request_queue
*q
= rq
->q
;
2911 unsigned long flags
;
2913 WARN_ON_ONCE(q
->mq_ops
);
2915 if (blk_update_bidi_request(rq
, error
, nr_bytes
, bidi_bytes
))
2918 spin_lock_irqsave(q
->queue_lock
, flags
);
2919 blk_finish_request(rq
, error
);
2920 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2926 * __blk_end_bidi_request - Complete a bidi request with queue lock held
2927 * @rq: the request to complete
2928 * @error: block status code
2929 * @nr_bytes: number of bytes to complete @rq
2930 * @bidi_bytes: number of bytes to complete @rq->next_rq
2933 * Identical to blk_end_bidi_request() except that queue lock is
2934 * assumed to be locked on entry and remains so on return.
2937 * %false - we are done with this request
2938 * %true - still buffers pending for this request
2940 static bool __blk_end_bidi_request(struct request
*rq
, blk_status_t error
,
2941 unsigned int nr_bytes
, unsigned int bidi_bytes
)
2943 lockdep_assert_held(rq
->q
->queue_lock
);
2944 WARN_ON_ONCE(rq
->q
->mq_ops
);
2946 if (blk_update_bidi_request(rq
, error
, nr_bytes
, bidi_bytes
))
2949 blk_finish_request(rq
, error
);
2955 * blk_end_request - Helper function for drivers to complete the request.
2956 * @rq: the request being processed
2957 * @error: block status code
2958 * @nr_bytes: number of bytes to complete
2961 * Ends I/O on a number of bytes attached to @rq.
2962 * If @rq has leftover, sets it up for the next range of segments.
2965 * %false - we are done with this request
2966 * %true - still buffers pending for this request
2968 bool blk_end_request(struct request
*rq
, blk_status_t error
,
2969 unsigned int nr_bytes
)
2971 WARN_ON_ONCE(rq
->q
->mq_ops
);
2972 return blk_end_bidi_request(rq
, error
, nr_bytes
, 0);
2974 EXPORT_SYMBOL(blk_end_request
);
2977 * blk_end_request_all - Helper function for drives to finish the request.
2978 * @rq: the request to finish
2979 * @error: block status code
2982 * Completely finish @rq.
2984 void blk_end_request_all(struct request
*rq
, blk_status_t error
)
2987 unsigned int bidi_bytes
= 0;
2989 if (unlikely(blk_bidi_rq(rq
)))
2990 bidi_bytes
= blk_rq_bytes(rq
->next_rq
);
2992 pending
= blk_end_bidi_request(rq
, error
, blk_rq_bytes(rq
), bidi_bytes
);
2995 EXPORT_SYMBOL(blk_end_request_all
);
2998 * __blk_end_request - Helper function for drivers to complete the request.
2999 * @rq: the request being processed
3000 * @error: block status code
3001 * @nr_bytes: number of bytes to complete
3004 * Must be called with queue lock held unlike blk_end_request().
3007 * %false - we are done with this request
3008 * %true - still buffers pending for this request
3010 bool __blk_end_request(struct request
*rq
, blk_status_t error
,
3011 unsigned int nr_bytes
)
3013 lockdep_assert_held(rq
->q
->queue_lock
);
3014 WARN_ON_ONCE(rq
->q
->mq_ops
);
3016 return __blk_end_bidi_request(rq
, error
, nr_bytes
, 0);
3018 EXPORT_SYMBOL(__blk_end_request
);
3021 * __blk_end_request_all - Helper function for drives to finish the request.
3022 * @rq: the request to finish
3023 * @error: block status code
3026 * Completely finish @rq. Must be called with queue lock held.
3028 void __blk_end_request_all(struct request
*rq
, blk_status_t error
)
3031 unsigned int bidi_bytes
= 0;
3033 lockdep_assert_held(rq
->q
->queue_lock
);
3034 WARN_ON_ONCE(rq
->q
->mq_ops
);
3036 if (unlikely(blk_bidi_rq(rq
)))
3037 bidi_bytes
= blk_rq_bytes(rq
->next_rq
);
3039 pending
= __blk_end_bidi_request(rq
, error
, blk_rq_bytes(rq
), bidi_bytes
);
3042 EXPORT_SYMBOL(__blk_end_request_all
);
3045 * __blk_end_request_cur - Helper function to finish the current request chunk.
3046 * @rq: the request to finish the current chunk for
3047 * @error: block status code
3050 * Complete the current consecutively mapped chunk from @rq. Must
3051 * be called with queue lock held.
3054 * %false - we are done with this request
3055 * %true - still buffers pending for this request
3057 bool __blk_end_request_cur(struct request
*rq
, blk_status_t error
)
3059 return __blk_end_request(rq
, error
, blk_rq_cur_bytes(rq
));
3061 EXPORT_SYMBOL(__blk_end_request_cur
);
3063 void blk_rq_bio_prep(struct request_queue
*q
, struct request
*rq
,
3066 if (bio_has_data(bio
))
3067 rq
->nr_phys_segments
= bio_phys_segments(q
, bio
);
3068 else if (bio_op(bio
) == REQ_OP_DISCARD
)
3069 rq
->nr_phys_segments
= 1;
3071 rq
->__data_len
= bio
->bi_iter
.bi_size
;
3072 rq
->bio
= rq
->biotail
= bio
;
3075 rq
->rq_disk
= bio
->bi_disk
;
3078 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
3080 * rq_flush_dcache_pages - Helper function to flush all pages in a request
3081 * @rq: the request to be flushed
3084 * Flush all pages in @rq.
3086 void rq_flush_dcache_pages(struct request
*rq
)
3088 struct req_iterator iter
;
3089 struct bio_vec bvec
;
3091 rq_for_each_segment(bvec
, rq
, iter
)
3092 flush_dcache_page(bvec
.bv_page
);
3094 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages
);
3098 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
3099 * @q : the queue of the device being checked
3102 * Check if underlying low-level drivers of a device are busy.
3103 * If the drivers want to export their busy state, they must set own
3104 * exporting function using blk_queue_lld_busy() first.
3106 * Basically, this function is used only by request stacking drivers
3107 * to stop dispatching requests to underlying devices when underlying
3108 * devices are busy. This behavior helps more I/O merging on the queue
3109 * of the request stacking driver and prevents I/O throughput regression
3110 * on burst I/O load.
3113 * 0 - Not busy (The request stacking driver should dispatch request)
3114 * 1 - Busy (The request stacking driver should stop dispatching request)
3116 int blk_lld_busy(struct request_queue
*q
)
3119 return q
->lld_busy_fn(q
);
3123 EXPORT_SYMBOL_GPL(blk_lld_busy
);
3126 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
3127 * @rq: the clone request to be cleaned up
3130 * Free all bios in @rq for a cloned request.
3132 void blk_rq_unprep_clone(struct request
*rq
)
3136 while ((bio
= rq
->bio
) != NULL
) {
3137 rq
->bio
= bio
->bi_next
;
3142 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone
);
3145 * Copy attributes of the original request to the clone request.
3146 * The actual data parts (e.g. ->cmd, ->sense) are not copied.
3148 static void __blk_rq_prep_clone(struct request
*dst
, struct request
*src
)
3150 dst
->cpu
= src
->cpu
;
3151 dst
->__sector
= blk_rq_pos(src
);
3152 dst
->__data_len
= blk_rq_bytes(src
);
3153 dst
->nr_phys_segments
= src
->nr_phys_segments
;
3154 dst
->ioprio
= src
->ioprio
;
3155 dst
->extra_len
= src
->extra_len
;
3159 * blk_rq_prep_clone - Helper function to setup clone request
3160 * @rq: the request to be setup
3161 * @rq_src: original request to be cloned
3162 * @bs: bio_set that bios for clone are allocated from
3163 * @gfp_mask: memory allocation mask for bio
3164 * @bio_ctr: setup function to be called for each clone bio.
3165 * Returns %0 for success, non %0 for failure.
3166 * @data: private data to be passed to @bio_ctr
3169 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
3170 * The actual data parts of @rq_src (e.g. ->cmd, ->sense)
3171 * are not copied, and copying such parts is the caller's responsibility.
3172 * Also, pages which the original bios are pointing to are not copied
3173 * and the cloned bios just point same pages.
3174 * So cloned bios must be completed before original bios, which means
3175 * the caller must complete @rq before @rq_src.
3177 int blk_rq_prep_clone(struct request
*rq
, struct request
*rq_src
,
3178 struct bio_set
*bs
, gfp_t gfp_mask
,
3179 int (*bio_ctr
)(struct bio
*, struct bio
*, void *),
3182 struct bio
*bio
, *bio_src
;
3187 __rq_for_each_bio(bio_src
, rq_src
) {
3188 bio
= bio_clone_fast(bio_src
, gfp_mask
, bs
);
3192 if (bio_ctr
&& bio_ctr(bio
, bio_src
, data
))
3196 rq
->biotail
->bi_next
= bio
;
3199 rq
->bio
= rq
->biotail
= bio
;
3202 __blk_rq_prep_clone(rq
, rq_src
);
3209 blk_rq_unprep_clone(rq
);
3213 EXPORT_SYMBOL_GPL(blk_rq_prep_clone
);
3215 int kblockd_schedule_work(struct work_struct
*work
)
3217 return queue_work(kblockd_workqueue
, work
);
3219 EXPORT_SYMBOL(kblockd_schedule_work
);
3221 int kblockd_schedule_work_on(int cpu
, struct work_struct
*work
)
3223 return queue_work_on(cpu
, kblockd_workqueue
, work
);
3225 EXPORT_SYMBOL(kblockd_schedule_work_on
);
3227 int kblockd_mod_delayed_work_on(int cpu
, struct delayed_work
*dwork
,
3228 unsigned long delay
)
3230 return mod_delayed_work_on(cpu
, kblockd_workqueue
, dwork
, delay
);
3232 EXPORT_SYMBOL(kblockd_mod_delayed_work_on
);
3234 int kblockd_schedule_delayed_work(struct delayed_work
*dwork
,
3235 unsigned long delay
)
3237 return queue_delayed_work(kblockd_workqueue
, dwork
, delay
);
3239 EXPORT_SYMBOL(kblockd_schedule_delayed_work
);
3241 int kblockd_schedule_delayed_work_on(int cpu
, struct delayed_work
*dwork
,
3242 unsigned long delay
)
3244 return queue_delayed_work_on(cpu
, kblockd_workqueue
, dwork
, delay
);
3246 EXPORT_SYMBOL(kblockd_schedule_delayed_work_on
);
3249 * blk_start_plug - initialize blk_plug and track it inside the task_struct
3250 * @plug: The &struct blk_plug that needs to be initialized
3253 * Tracking blk_plug inside the task_struct will help with auto-flushing the
3254 * pending I/O should the task end up blocking between blk_start_plug() and
3255 * blk_finish_plug(). This is important from a performance perspective, but
3256 * also ensures that we don't deadlock. For instance, if the task is blocking
3257 * for a memory allocation, memory reclaim could end up wanting to free a
3258 * page belonging to that request that is currently residing in our private
3259 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
3260 * this kind of deadlock.
3262 void blk_start_plug(struct blk_plug
*plug
)
3264 struct task_struct
*tsk
= current
;
3267 * If this is a nested plug, don't actually assign it.
3272 INIT_LIST_HEAD(&plug
->list
);
3273 INIT_LIST_HEAD(&plug
->mq_list
);
3274 INIT_LIST_HEAD(&plug
->cb_list
);
3276 * Store ordering should not be needed here, since a potential
3277 * preempt will imply a full memory barrier
3281 EXPORT_SYMBOL(blk_start_plug
);
3283 static int plug_rq_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
3285 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
3286 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
3288 return !(rqa
->q
< rqb
->q
||
3289 (rqa
->q
== rqb
->q
&& blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
3293 * If 'from_schedule' is true, then postpone the dispatch of requests
3294 * until a safe kblockd context. We due this to avoid accidental big
3295 * additional stack usage in driver dispatch, in places where the originally
3296 * plugger did not intend it.
3298 static void queue_unplugged(struct request_queue
*q
, unsigned int depth
,
3300 __releases(q
->queue_lock
)
3302 lockdep_assert_held(q
->queue_lock
);
3304 trace_block_unplug(q
, depth
, !from_schedule
);
3307 blk_run_queue_async(q
);
3310 spin_unlock(q
->queue_lock
);
3313 static void flush_plug_callbacks(struct blk_plug
*plug
, bool from_schedule
)
3315 LIST_HEAD(callbacks
);
3317 while (!list_empty(&plug
->cb_list
)) {
3318 list_splice_init(&plug
->cb_list
, &callbacks
);
3320 while (!list_empty(&callbacks
)) {
3321 struct blk_plug_cb
*cb
= list_first_entry(&callbacks
,
3324 list_del(&cb
->list
);
3325 cb
->callback(cb
, from_schedule
);
3330 struct blk_plug_cb
*blk_check_plugged(blk_plug_cb_fn unplug
, void *data
,
3333 struct blk_plug
*plug
= current
->plug
;
3334 struct blk_plug_cb
*cb
;
3339 list_for_each_entry(cb
, &plug
->cb_list
, list
)
3340 if (cb
->callback
== unplug
&& cb
->data
== data
)
3343 /* Not currently on the callback list */
3344 BUG_ON(size
< sizeof(*cb
));
3345 cb
= kzalloc(size
, GFP_ATOMIC
);
3348 cb
->callback
= unplug
;
3349 list_add(&cb
->list
, &plug
->cb_list
);
3353 EXPORT_SYMBOL(blk_check_plugged
);
3355 void blk_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
3357 struct request_queue
*q
;
3358 unsigned long flags
;
3363 flush_plug_callbacks(plug
, from_schedule
);
3365 if (!list_empty(&plug
->mq_list
))
3366 blk_mq_flush_plug_list(plug
, from_schedule
);
3368 if (list_empty(&plug
->list
))
3371 list_splice_init(&plug
->list
, &list
);
3373 list_sort(NULL
, &list
, plug_rq_cmp
);
3379 * Save and disable interrupts here, to avoid doing it for every
3380 * queue lock we have to take.
3382 local_irq_save(flags
);
3383 while (!list_empty(&list
)) {
3384 rq
= list_entry_rq(list
.next
);
3385 list_del_init(&rq
->queuelist
);
3389 * This drops the queue lock
3392 queue_unplugged(q
, depth
, from_schedule
);
3395 spin_lock(q
->queue_lock
);
3399 * Short-circuit if @q is dead
3401 if (unlikely(blk_queue_dying(q
))) {
3402 __blk_end_request_all(rq
, BLK_STS_IOERR
);
3407 * rq is already accounted, so use raw insert
3409 if (op_is_flush(rq
->cmd_flags
))
3410 __elv_add_request(q
, rq
, ELEVATOR_INSERT_FLUSH
);
3412 __elv_add_request(q
, rq
, ELEVATOR_INSERT_SORT_MERGE
);
3418 * This drops the queue lock
3421 queue_unplugged(q
, depth
, from_schedule
);
3423 local_irq_restore(flags
);
3426 void blk_finish_plug(struct blk_plug
*plug
)
3428 if (plug
!= current
->plug
)
3430 blk_flush_plug_list(plug
, false);
3432 current
->plug
= NULL
;
3434 EXPORT_SYMBOL(blk_finish_plug
);
3438 * blk_pm_runtime_init - Block layer runtime PM initialization routine
3439 * @q: the queue of the device
3440 * @dev: the device the queue belongs to
3443 * Initialize runtime-PM-related fields for @q and start auto suspend for
3444 * @dev. Drivers that want to take advantage of request-based runtime PM
3445 * should call this function after @dev has been initialized, and its
3446 * request queue @q has been allocated, and runtime PM for it can not happen
3447 * yet(either due to disabled/forbidden or its usage_count > 0). In most
3448 * cases, driver should call this function before any I/O has taken place.
3450 * This function takes care of setting up using auto suspend for the device,
3451 * the autosuspend delay is set to -1 to make runtime suspend impossible
3452 * until an updated value is either set by user or by driver. Drivers do
3453 * not need to touch other autosuspend settings.
3455 * The block layer runtime PM is request based, so only works for drivers
3456 * that use request as their IO unit instead of those directly use bio's.
3458 void blk_pm_runtime_init(struct request_queue
*q
, struct device
*dev
)
3460 /* not support for RQF_PM and ->rpm_status in blk-mq yet */
3465 q
->rpm_status
= RPM_ACTIVE
;
3466 pm_runtime_set_autosuspend_delay(q
->dev
, -1);
3467 pm_runtime_use_autosuspend(q
->dev
);
3469 EXPORT_SYMBOL(blk_pm_runtime_init
);
3472 * blk_pre_runtime_suspend - Pre runtime suspend check
3473 * @q: the queue of the device
3476 * This function will check if runtime suspend is allowed for the device
3477 * by examining if there are any requests pending in the queue. If there
3478 * are requests pending, the device can not be runtime suspended; otherwise,
3479 * the queue's status will be updated to SUSPENDING and the driver can
3480 * proceed to suspend the device.
3482 * For the not allowed case, we mark last busy for the device so that
3483 * runtime PM core will try to autosuspend it some time later.
3485 * This function should be called near the start of the device's
3486 * runtime_suspend callback.
3489 * 0 - OK to runtime suspend the device
3490 * -EBUSY - Device should not be runtime suspended
3492 int blk_pre_runtime_suspend(struct request_queue
*q
)
3499 spin_lock_irq(q
->queue_lock
);
3500 if (q
->nr_pending
) {
3502 pm_runtime_mark_last_busy(q
->dev
);
3504 q
->rpm_status
= RPM_SUSPENDING
;
3506 spin_unlock_irq(q
->queue_lock
);
3509 EXPORT_SYMBOL(blk_pre_runtime_suspend
);
3512 * blk_post_runtime_suspend - Post runtime suspend processing
3513 * @q: the queue of the device
3514 * @err: return value of the device's runtime_suspend function
3517 * Update the queue's runtime status according to the return value of the
3518 * device's runtime suspend function and mark last busy for the device so
3519 * that PM core will try to auto suspend the device at a later time.
3521 * This function should be called near the end of the device's
3522 * runtime_suspend callback.
3524 void blk_post_runtime_suspend(struct request_queue
*q
, int err
)
3529 spin_lock_irq(q
->queue_lock
);
3531 q
->rpm_status
= RPM_SUSPENDED
;
3533 q
->rpm_status
= RPM_ACTIVE
;
3534 pm_runtime_mark_last_busy(q
->dev
);
3536 spin_unlock_irq(q
->queue_lock
);
3538 EXPORT_SYMBOL(blk_post_runtime_suspend
);
3541 * blk_pre_runtime_resume - Pre runtime resume processing
3542 * @q: the queue of the device
3545 * Update the queue's runtime status to RESUMING in preparation for the
3546 * runtime resume of the device.
3548 * This function should be called near the start of the device's
3549 * runtime_resume callback.
3551 void blk_pre_runtime_resume(struct request_queue
*q
)
3556 spin_lock_irq(q
->queue_lock
);
3557 q
->rpm_status
= RPM_RESUMING
;
3558 spin_unlock_irq(q
->queue_lock
);
3560 EXPORT_SYMBOL(blk_pre_runtime_resume
);
3563 * blk_post_runtime_resume - Post runtime resume processing
3564 * @q: the queue of the device
3565 * @err: return value of the device's runtime_resume function
3568 * Update the queue's runtime status according to the return value of the
3569 * device's runtime_resume function. If it is successfully resumed, process
3570 * the requests that are queued into the device's queue when it is resuming
3571 * and then mark last busy and initiate autosuspend for it.
3573 * This function should be called near the end of the device's
3574 * runtime_resume callback.
3576 void blk_post_runtime_resume(struct request_queue
*q
, int err
)
3581 spin_lock_irq(q
->queue_lock
);
3583 q
->rpm_status
= RPM_ACTIVE
;
3585 pm_runtime_mark_last_busy(q
->dev
);
3586 pm_request_autosuspend(q
->dev
);
3588 q
->rpm_status
= RPM_SUSPENDED
;
3590 spin_unlock_irq(q
->queue_lock
);
3592 EXPORT_SYMBOL(blk_post_runtime_resume
);
3595 * blk_set_runtime_active - Force runtime status of the queue to be active
3596 * @q: the queue of the device
3598 * If the device is left runtime suspended during system suspend the resume
3599 * hook typically resumes the device and corrects runtime status
3600 * accordingly. However, that does not affect the queue runtime PM status
3601 * which is still "suspended". This prevents processing requests from the
3604 * This function can be used in driver's resume hook to correct queue
3605 * runtime PM status and re-enable peeking requests from the queue. It
3606 * should be called before first request is added to the queue.
3608 void blk_set_runtime_active(struct request_queue
*q
)
3610 spin_lock_irq(q
->queue_lock
);
3611 q
->rpm_status
= RPM_ACTIVE
;
3612 pm_runtime_mark_last_busy(q
->dev
);
3613 pm_request_autosuspend(q
->dev
);
3614 spin_unlock_irq(q
->queue_lock
);
3616 EXPORT_SYMBOL(blk_set_runtime_active
);
3619 int __init
blk_dev_init(void)
3621 BUILD_BUG_ON(REQ_OP_LAST
>= (1 << REQ_OP_BITS
));
3622 BUILD_BUG_ON(REQ_OP_BITS
+ REQ_FLAG_BITS
> 8 *
3623 FIELD_SIZEOF(struct request
, cmd_flags
));
3624 BUILD_BUG_ON(REQ_OP_BITS
+ REQ_FLAG_BITS
> 8 *
3625 FIELD_SIZEOF(struct bio
, bi_opf
));
3627 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
3628 kblockd_workqueue
= alloc_workqueue("kblockd",
3629 WQ_MEM_RECLAIM
| WQ_HIGHPRI
, 0);
3630 if (!kblockd_workqueue
)
3631 panic("Failed to create kblockd\n");
3633 request_cachep
= kmem_cache_create("blkdev_requests",
3634 sizeof(struct request
), 0, SLAB_PANIC
, NULL
);
3636 blk_requestq_cachep
= kmem_cache_create("request_queue",
3637 sizeof(struct request_queue
), 0, SLAB_PANIC
, NULL
);
3639 #ifdef CONFIG_DEBUG_FS
3640 blk_debugfs_root
= debugfs_create_dir("block", NULL
);