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>
37 #define CREATE_TRACE_POINTS
38 #include <trace/events/block.h>
44 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap
);
45 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap
);
46 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete
);
47 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split
);
48 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug
);
50 DEFINE_IDA(blk_queue_ida
);
53 * For the allocated request tables
55 struct kmem_cache
*request_cachep
;
58 * For queue allocation
60 struct kmem_cache
*blk_requestq_cachep
;
63 * Controlling structure to kblockd
65 static struct workqueue_struct
*kblockd_workqueue
;
67 static void blk_clear_congested(struct request_list
*rl
, int sync
)
69 #ifdef CONFIG_CGROUP_WRITEBACK
70 clear_wb_congested(rl
->blkg
->wb_congested
, sync
);
73 * If !CGROUP_WRITEBACK, all blkg's map to bdi->wb and we shouldn't
74 * flip its congestion state for events on other blkcgs.
76 if (rl
== &rl
->q
->root_rl
)
77 clear_wb_congested(rl
->q
->backing_dev_info
.wb
.congested
, sync
);
81 static void blk_set_congested(struct request_list
*rl
, int sync
)
83 #ifdef CONFIG_CGROUP_WRITEBACK
84 set_wb_congested(rl
->blkg
->wb_congested
, sync
);
86 /* see blk_clear_congested() */
87 if (rl
== &rl
->q
->root_rl
)
88 set_wb_congested(rl
->q
->backing_dev_info
.wb
.congested
, sync
);
92 void blk_queue_congestion_threshold(struct request_queue
*q
)
96 nr
= q
->nr_requests
- (q
->nr_requests
/ 8) + 1;
97 if (nr
> q
->nr_requests
)
99 q
->nr_congestion_on
= nr
;
101 nr
= q
->nr_requests
- (q
->nr_requests
/ 8) - (q
->nr_requests
/ 16) - 1;
104 q
->nr_congestion_off
= nr
;
108 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
111 * Locates the passed device's request queue and returns the address of its
112 * backing_dev_info. This function can only be called if @bdev is opened
113 * and the return value is never NULL.
115 struct backing_dev_info
*blk_get_backing_dev_info(struct block_device
*bdev
)
117 struct request_queue
*q
= bdev_get_queue(bdev
);
119 return &q
->backing_dev_info
;
121 EXPORT_SYMBOL(blk_get_backing_dev_info
);
123 void blk_rq_init(struct request_queue
*q
, struct request
*rq
)
125 memset(rq
, 0, sizeof(*rq
));
127 INIT_LIST_HEAD(&rq
->queuelist
);
128 INIT_LIST_HEAD(&rq
->timeout_list
);
131 rq
->__sector
= (sector_t
) -1;
132 INIT_HLIST_NODE(&rq
->hash
);
133 RB_CLEAR_NODE(&rq
->rb_node
);
135 rq
->cmd_len
= BLK_MAX_CDB
;
137 rq
->start_time
= jiffies
;
138 set_start_time_ns(rq
);
141 EXPORT_SYMBOL(blk_rq_init
);
143 static void req_bio_endio(struct request
*rq
, struct bio
*bio
,
144 unsigned int nbytes
, int error
)
147 bio
->bi_error
= error
;
149 if (unlikely(rq
->rq_flags
& RQF_QUIET
))
150 bio_set_flag(bio
, BIO_QUIET
);
152 bio_advance(bio
, nbytes
);
154 /* don't actually finish bio if it's part of flush sequence */
155 if (bio
->bi_iter
.bi_size
== 0 && !(rq
->rq_flags
& RQF_FLUSH_SEQ
))
159 void blk_dump_rq_flags(struct request
*rq
, char *msg
)
163 printk(KERN_INFO
"%s: dev %s: type=%x, flags=%llx\n", msg
,
164 rq
->rq_disk
? rq
->rq_disk
->disk_name
: "?", rq
->cmd_type
,
165 (unsigned long long) rq
->cmd_flags
);
167 printk(KERN_INFO
" sector %llu, nr/cnr %u/%u\n",
168 (unsigned long long)blk_rq_pos(rq
),
169 blk_rq_sectors(rq
), blk_rq_cur_sectors(rq
));
170 printk(KERN_INFO
" bio %p, biotail %p, len %u\n",
171 rq
->bio
, rq
->biotail
, blk_rq_bytes(rq
));
173 if (rq
->cmd_type
== REQ_TYPE_BLOCK_PC
) {
174 printk(KERN_INFO
" cdb: ");
175 for (bit
= 0; bit
< BLK_MAX_CDB
; bit
++)
176 printk("%02x ", rq
->cmd
[bit
]);
180 EXPORT_SYMBOL(blk_dump_rq_flags
);
182 static void blk_delay_work(struct work_struct
*work
)
184 struct request_queue
*q
;
186 q
= container_of(work
, struct request_queue
, delay_work
.work
);
187 spin_lock_irq(q
->queue_lock
);
189 spin_unlock_irq(q
->queue_lock
);
193 * blk_delay_queue - restart queueing after defined interval
194 * @q: The &struct request_queue in question
195 * @msecs: Delay in msecs
198 * Sometimes queueing needs to be postponed for a little while, to allow
199 * resources to come back. This function will make sure that queueing is
200 * restarted around the specified time. Queue lock must be held.
202 void blk_delay_queue(struct request_queue
*q
, unsigned long msecs
)
204 if (likely(!blk_queue_dead(q
)))
205 queue_delayed_work(kblockd_workqueue
, &q
->delay_work
,
206 msecs_to_jiffies(msecs
));
208 EXPORT_SYMBOL(blk_delay_queue
);
211 * blk_start_queue_async - asynchronously restart a previously stopped queue
212 * @q: The &struct request_queue in question
215 * blk_start_queue_async() will clear the stop flag on the queue, and
216 * ensure that the request_fn for the queue is run from an async
219 void blk_start_queue_async(struct request_queue
*q
)
221 queue_flag_clear(QUEUE_FLAG_STOPPED
, q
);
222 blk_run_queue_async(q
);
224 EXPORT_SYMBOL(blk_start_queue_async
);
227 * blk_start_queue - restart a previously stopped queue
228 * @q: The &struct request_queue in question
231 * blk_start_queue() will clear the stop flag on the queue, and call
232 * the request_fn for the queue if it was in a stopped state when
233 * entered. Also see blk_stop_queue(). Queue lock must be held.
235 void blk_start_queue(struct request_queue
*q
)
237 WARN_ON(!irqs_disabled());
239 queue_flag_clear(QUEUE_FLAG_STOPPED
, q
);
242 EXPORT_SYMBOL(blk_start_queue
);
245 * blk_stop_queue - stop a queue
246 * @q: The &struct request_queue in question
249 * The Linux block layer assumes that a block driver will consume all
250 * entries on the request queue when the request_fn strategy is called.
251 * Often this will not happen, because of hardware limitations (queue
252 * depth settings). If a device driver gets a 'queue full' response,
253 * or if it simply chooses not to queue more I/O at one point, it can
254 * call this function to prevent the request_fn from being called until
255 * the driver has signalled it's ready to go again. This happens by calling
256 * blk_start_queue() to restart queue operations. Queue lock must be held.
258 void blk_stop_queue(struct request_queue
*q
)
260 cancel_delayed_work(&q
->delay_work
);
261 queue_flag_set(QUEUE_FLAG_STOPPED
, q
);
263 EXPORT_SYMBOL(blk_stop_queue
);
266 * blk_sync_queue - cancel any pending callbacks on a queue
270 * The block layer may perform asynchronous callback activity
271 * on a queue, such as calling the unplug function after a timeout.
272 * A block device may call blk_sync_queue to ensure that any
273 * such activity is cancelled, thus allowing it to release resources
274 * that the callbacks might use. The caller must already have made sure
275 * that its ->make_request_fn will not re-add plugging prior to calling
278 * This function does not cancel any asynchronous activity arising
279 * out of elevator or throttling code. That would require elevator_exit()
280 * and blkcg_exit_queue() to be called with queue lock initialized.
283 void blk_sync_queue(struct request_queue
*q
)
285 del_timer_sync(&q
->timeout
);
288 struct blk_mq_hw_ctx
*hctx
;
291 queue_for_each_hw_ctx(q
, hctx
, i
) {
292 cancel_work_sync(&hctx
->run_work
);
293 cancel_delayed_work_sync(&hctx
->delay_work
);
296 cancel_delayed_work_sync(&q
->delay_work
);
299 EXPORT_SYMBOL(blk_sync_queue
);
302 * __blk_run_queue_uncond - run a queue whether or not it has been stopped
303 * @q: The queue to run
306 * Invoke request handling on a queue if there are any pending requests.
307 * May be used to restart request handling after a request has completed.
308 * This variant runs the queue whether or not the queue has been
309 * stopped. Must be called with the queue lock held and interrupts
310 * disabled. See also @blk_run_queue.
312 inline void __blk_run_queue_uncond(struct request_queue
*q
)
314 if (unlikely(blk_queue_dead(q
)))
318 * Some request_fn implementations, e.g. scsi_request_fn(), unlock
319 * the queue lock internally. As a result multiple threads may be
320 * running such a request function concurrently. Keep track of the
321 * number of active request_fn invocations such that blk_drain_queue()
322 * can wait until all these request_fn calls have finished.
324 q
->request_fn_active
++;
326 q
->request_fn_active
--;
328 EXPORT_SYMBOL_GPL(__blk_run_queue_uncond
);
331 * __blk_run_queue - run a single device queue
332 * @q: The queue to run
335 * See @blk_run_queue. This variant must be called with the queue lock
336 * held and interrupts disabled.
338 void __blk_run_queue(struct request_queue
*q
)
340 if (unlikely(blk_queue_stopped(q
)))
343 __blk_run_queue_uncond(q
);
345 EXPORT_SYMBOL(__blk_run_queue
);
348 * blk_run_queue_async - run a single device queue in workqueue context
349 * @q: The queue to run
352 * Tells kblockd to perform the equivalent of @blk_run_queue on behalf
353 * of us. The caller must hold the queue lock.
355 void blk_run_queue_async(struct request_queue
*q
)
357 if (likely(!blk_queue_stopped(q
) && !blk_queue_dead(q
)))
358 mod_delayed_work(kblockd_workqueue
, &q
->delay_work
, 0);
360 EXPORT_SYMBOL(blk_run_queue_async
);
363 * blk_run_queue - run a single device queue
364 * @q: The queue to run
367 * Invoke request handling on this queue, if it has pending work to do.
368 * May be used to restart queueing when a request has completed.
370 void blk_run_queue(struct request_queue
*q
)
374 spin_lock_irqsave(q
->queue_lock
, flags
);
376 spin_unlock_irqrestore(q
->queue_lock
, flags
);
378 EXPORT_SYMBOL(blk_run_queue
);
380 void blk_put_queue(struct request_queue
*q
)
382 kobject_put(&q
->kobj
);
384 EXPORT_SYMBOL(blk_put_queue
);
387 * __blk_drain_queue - drain requests from request_queue
389 * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
391 * Drain requests from @q. If @drain_all is set, all requests are drained.
392 * If not, only ELVPRIV requests are drained. The caller is responsible
393 * for ensuring that no new requests which need to be drained are queued.
395 static void __blk_drain_queue(struct request_queue
*q
, bool drain_all
)
396 __releases(q
->queue_lock
)
397 __acquires(q
->queue_lock
)
401 lockdep_assert_held(q
->queue_lock
);
407 * The caller might be trying to drain @q before its
408 * elevator is initialized.
411 elv_drain_elevator(q
);
413 blkcg_drain_queue(q
);
416 * This function might be called on a queue which failed
417 * driver init after queue creation or is not yet fully
418 * active yet. Some drivers (e.g. fd and loop) get unhappy
419 * in such cases. Kick queue iff dispatch queue has
420 * something on it and @q has request_fn set.
422 if (!list_empty(&q
->queue_head
) && q
->request_fn
)
425 drain
|= q
->nr_rqs_elvpriv
;
426 drain
|= q
->request_fn_active
;
429 * Unfortunately, requests are queued at and tracked from
430 * multiple places and there's no single counter which can
431 * be drained. Check all the queues and counters.
434 struct blk_flush_queue
*fq
= blk_get_flush_queue(q
, NULL
);
435 drain
|= !list_empty(&q
->queue_head
);
436 for (i
= 0; i
< 2; i
++) {
437 drain
|= q
->nr_rqs
[i
];
438 drain
|= q
->in_flight
[i
];
440 drain
|= !list_empty(&fq
->flush_queue
[i
]);
447 spin_unlock_irq(q
->queue_lock
);
451 spin_lock_irq(q
->queue_lock
);
455 * With queue marked dead, any woken up waiter will fail the
456 * allocation path, so the wakeup chaining is lost and we're
457 * left with hung waiters. We need to wake up those waiters.
460 struct request_list
*rl
;
462 blk_queue_for_each_rl(rl
, q
)
463 for (i
= 0; i
< ARRAY_SIZE(rl
->wait
); i
++)
464 wake_up_all(&rl
->wait
[i
]);
469 * blk_queue_bypass_start - enter queue bypass mode
470 * @q: queue of interest
472 * In bypass mode, only the dispatch FIFO queue of @q is used. This
473 * function makes @q enter bypass mode and drains all requests which were
474 * throttled or issued before. On return, it's guaranteed that no request
475 * is being throttled or has ELVPRIV set and blk_queue_bypass() %true
476 * inside queue or RCU read lock.
478 void blk_queue_bypass_start(struct request_queue
*q
)
480 spin_lock_irq(q
->queue_lock
);
482 queue_flag_set(QUEUE_FLAG_BYPASS
, q
);
483 spin_unlock_irq(q
->queue_lock
);
486 * Queues start drained. Skip actual draining till init is
487 * complete. This avoids lenghty delays during queue init which
488 * can happen many times during boot.
490 if (blk_queue_init_done(q
)) {
491 spin_lock_irq(q
->queue_lock
);
492 __blk_drain_queue(q
, false);
493 spin_unlock_irq(q
->queue_lock
);
495 /* ensure blk_queue_bypass() is %true inside RCU read lock */
499 EXPORT_SYMBOL_GPL(blk_queue_bypass_start
);
502 * blk_queue_bypass_end - leave queue bypass mode
503 * @q: queue of interest
505 * Leave bypass mode and restore the normal queueing behavior.
507 void blk_queue_bypass_end(struct request_queue
*q
)
509 spin_lock_irq(q
->queue_lock
);
510 if (!--q
->bypass_depth
)
511 queue_flag_clear(QUEUE_FLAG_BYPASS
, q
);
512 WARN_ON_ONCE(q
->bypass_depth
< 0);
513 spin_unlock_irq(q
->queue_lock
);
515 EXPORT_SYMBOL_GPL(blk_queue_bypass_end
);
517 void blk_set_queue_dying(struct request_queue
*q
)
519 spin_lock_irq(q
->queue_lock
);
520 queue_flag_set(QUEUE_FLAG_DYING
, q
);
521 spin_unlock_irq(q
->queue_lock
);
524 blk_mq_wake_waiters(q
);
526 struct request_list
*rl
;
528 blk_queue_for_each_rl(rl
, q
) {
530 wake_up(&rl
->wait
[BLK_RW_SYNC
]);
531 wake_up(&rl
->wait
[BLK_RW_ASYNC
]);
536 EXPORT_SYMBOL_GPL(blk_set_queue_dying
);
539 * blk_cleanup_queue - shutdown a request queue
540 * @q: request queue to shutdown
542 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
543 * put it. All future requests will be failed immediately with -ENODEV.
545 void blk_cleanup_queue(struct request_queue
*q
)
547 spinlock_t
*lock
= q
->queue_lock
;
549 /* mark @q DYING, no new request or merges will be allowed afterwards */
550 mutex_lock(&q
->sysfs_lock
);
551 blk_set_queue_dying(q
);
555 * A dying queue is permanently in bypass mode till released. Note
556 * that, unlike blk_queue_bypass_start(), we aren't performing
557 * synchronize_rcu() after entering bypass mode to avoid the delay
558 * as some drivers create and destroy a lot of queues while
559 * probing. This is still safe because blk_release_queue() will be
560 * called only after the queue refcnt drops to zero and nothing,
561 * RCU or not, would be traversing the queue by then.
564 queue_flag_set(QUEUE_FLAG_BYPASS
, q
);
566 queue_flag_set(QUEUE_FLAG_NOMERGES
, q
);
567 queue_flag_set(QUEUE_FLAG_NOXMERGES
, q
);
568 queue_flag_set(QUEUE_FLAG_DYING
, q
);
569 spin_unlock_irq(lock
);
570 mutex_unlock(&q
->sysfs_lock
);
573 * Drain all requests queued before DYING marking. Set DEAD flag to
574 * prevent that q->request_fn() gets invoked after draining finished.
579 __blk_drain_queue(q
, true);
580 queue_flag_set(QUEUE_FLAG_DEAD
, q
);
581 spin_unlock_irq(lock
);
583 /* for synchronous bio-based driver finish in-flight integrity i/o */
584 blk_flush_integrity();
586 /* @q won't process any more request, flush async actions */
587 del_timer_sync(&q
->backing_dev_info
.laptop_mode_wb_timer
);
591 blk_mq_free_queue(q
);
592 percpu_ref_exit(&q
->q_usage_counter
);
595 if (q
->queue_lock
!= &q
->__queue_lock
)
596 q
->queue_lock
= &q
->__queue_lock
;
597 spin_unlock_irq(lock
);
599 bdi_unregister(&q
->backing_dev_info
);
601 /* @q is and will stay empty, shutdown and put */
604 EXPORT_SYMBOL(blk_cleanup_queue
);
606 /* Allocate memory local to the request queue */
607 static void *alloc_request_struct(gfp_t gfp_mask
, void *data
)
609 int nid
= (int)(long)data
;
610 return kmem_cache_alloc_node(request_cachep
, gfp_mask
, nid
);
613 static void free_request_struct(void *element
, void *unused
)
615 kmem_cache_free(request_cachep
, element
);
618 int blk_init_rl(struct request_list
*rl
, struct request_queue
*q
,
621 if (unlikely(rl
->rq_pool
))
625 rl
->count
[BLK_RW_SYNC
] = rl
->count
[BLK_RW_ASYNC
] = 0;
626 rl
->starved
[BLK_RW_SYNC
] = rl
->starved
[BLK_RW_ASYNC
] = 0;
627 init_waitqueue_head(&rl
->wait
[BLK_RW_SYNC
]);
628 init_waitqueue_head(&rl
->wait
[BLK_RW_ASYNC
]);
630 rl
->rq_pool
= mempool_create_node(BLKDEV_MIN_RQ
, alloc_request_struct
,
632 (void *)(long)q
->node
, gfp_mask
,
640 void blk_exit_rl(struct request_list
*rl
)
643 mempool_destroy(rl
->rq_pool
);
646 struct request_queue
*blk_alloc_queue(gfp_t gfp_mask
)
648 return blk_alloc_queue_node(gfp_mask
, NUMA_NO_NODE
);
650 EXPORT_SYMBOL(blk_alloc_queue
);
652 int blk_queue_enter(struct request_queue
*q
, bool nowait
)
657 if (percpu_ref_tryget_live(&q
->q_usage_counter
))
663 ret
= wait_event_interruptible(q
->mq_freeze_wq
,
664 !atomic_read(&q
->mq_freeze_depth
) ||
666 if (blk_queue_dying(q
))
673 void blk_queue_exit(struct request_queue
*q
)
675 percpu_ref_put(&q
->q_usage_counter
);
678 static void blk_queue_usage_counter_release(struct percpu_ref
*ref
)
680 struct request_queue
*q
=
681 container_of(ref
, struct request_queue
, q_usage_counter
);
683 wake_up_all(&q
->mq_freeze_wq
);
686 static void blk_rq_timed_out_timer(unsigned long data
)
688 struct request_queue
*q
= (struct request_queue
*)data
;
690 kblockd_schedule_work(&q
->timeout_work
);
693 struct request_queue
*blk_alloc_queue_node(gfp_t gfp_mask
, int node_id
)
695 struct request_queue
*q
;
698 q
= kmem_cache_alloc_node(blk_requestq_cachep
,
699 gfp_mask
| __GFP_ZERO
, node_id
);
703 q
->id
= ida_simple_get(&blk_queue_ida
, 0, 0, gfp_mask
);
707 q
->bio_split
= bioset_create(BIO_POOL_SIZE
, 0);
711 q
->backing_dev_info
.ra_pages
=
712 (VM_MAX_READAHEAD
* 1024) / PAGE_SIZE
;
713 q
->backing_dev_info
.capabilities
= BDI_CAP_CGROUP_WRITEBACK
;
714 q
->backing_dev_info
.name
= "block";
717 err
= bdi_init(&q
->backing_dev_info
);
721 setup_timer(&q
->backing_dev_info
.laptop_mode_wb_timer
,
722 laptop_mode_timer_fn
, (unsigned long) q
);
723 setup_timer(&q
->timeout
, blk_rq_timed_out_timer
, (unsigned long) q
);
724 INIT_LIST_HEAD(&q
->queue_head
);
725 INIT_LIST_HEAD(&q
->timeout_list
);
726 INIT_LIST_HEAD(&q
->icq_list
);
727 #ifdef CONFIG_BLK_CGROUP
728 INIT_LIST_HEAD(&q
->blkg_list
);
730 INIT_DELAYED_WORK(&q
->delay_work
, blk_delay_work
);
732 kobject_init(&q
->kobj
, &blk_queue_ktype
);
734 mutex_init(&q
->sysfs_lock
);
735 spin_lock_init(&q
->__queue_lock
);
738 * By default initialize queue_lock to internal lock and driver can
739 * override it later if need be.
741 q
->queue_lock
= &q
->__queue_lock
;
744 * A queue starts its life with bypass turned on to avoid
745 * unnecessary bypass on/off overhead and nasty surprises during
746 * init. The initial bypass will be finished when the queue is
747 * registered by blk_register_queue().
750 __set_bit(QUEUE_FLAG_BYPASS
, &q
->queue_flags
);
752 init_waitqueue_head(&q
->mq_freeze_wq
);
755 * Init percpu_ref in atomic mode so that it's faster to shutdown.
756 * See blk_register_queue() for details.
758 if (percpu_ref_init(&q
->q_usage_counter
,
759 blk_queue_usage_counter_release
,
760 PERCPU_REF_INIT_ATOMIC
, GFP_KERNEL
))
763 if (blkcg_init_queue(q
))
769 percpu_ref_exit(&q
->q_usage_counter
);
771 bdi_destroy(&q
->backing_dev_info
);
773 bioset_free(q
->bio_split
);
775 ida_simple_remove(&blk_queue_ida
, q
->id
);
777 kmem_cache_free(blk_requestq_cachep
, q
);
780 EXPORT_SYMBOL(blk_alloc_queue_node
);
783 * blk_init_queue - prepare a request queue for use with a block device
784 * @rfn: The function to be called to process requests that have been
785 * placed on the queue.
786 * @lock: Request queue spin lock
789 * If a block device wishes to use the standard request handling procedures,
790 * which sorts requests and coalesces adjacent requests, then it must
791 * call blk_init_queue(). The function @rfn will be called when there
792 * are requests on the queue that need to be processed. If the device
793 * supports plugging, then @rfn may not be called immediately when requests
794 * are available on the queue, but may be called at some time later instead.
795 * Plugged queues are generally unplugged when a buffer belonging to one
796 * of the requests on the queue is needed, or due to memory pressure.
798 * @rfn is not required, or even expected, to remove all requests off the
799 * queue, but only as many as it can handle at a time. If it does leave
800 * requests on the queue, it is responsible for arranging that the requests
801 * get dealt with eventually.
803 * The queue spin lock must be held while manipulating the requests on the
804 * request queue; this lock will be taken also from interrupt context, so irq
805 * disabling is needed for it.
807 * Function returns a pointer to the initialized request queue, or %NULL if
811 * blk_init_queue() must be paired with a blk_cleanup_queue() call
812 * when the block device is deactivated (such as at module unload).
815 struct request_queue
*blk_init_queue(request_fn_proc
*rfn
, spinlock_t
*lock
)
817 return blk_init_queue_node(rfn
, lock
, NUMA_NO_NODE
);
819 EXPORT_SYMBOL(blk_init_queue
);
821 struct request_queue
*
822 blk_init_queue_node(request_fn_proc
*rfn
, spinlock_t
*lock
, int node_id
)
824 struct request_queue
*uninit_q
, *q
;
826 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, node_id
);
830 q
= blk_init_allocated_queue(uninit_q
, rfn
, lock
);
832 blk_cleanup_queue(uninit_q
);
836 EXPORT_SYMBOL(blk_init_queue_node
);
838 static blk_qc_t
blk_queue_bio(struct request_queue
*q
, struct bio
*bio
);
840 struct request_queue
*
841 blk_init_allocated_queue(struct request_queue
*q
, request_fn_proc
*rfn
,
847 q
->fq
= blk_alloc_flush_queue(q
, NUMA_NO_NODE
, 0);
851 if (blk_init_rl(&q
->root_rl
, q
, GFP_KERNEL
))
854 INIT_WORK(&q
->timeout_work
, blk_timeout_work
);
856 q
->prep_rq_fn
= NULL
;
857 q
->unprep_rq_fn
= NULL
;
858 q
->queue_flags
|= QUEUE_FLAG_DEFAULT
;
860 /* Override internal queue lock with supplied lock pointer */
862 q
->queue_lock
= lock
;
865 * This also sets hw/phys segments, boundary and size
867 blk_queue_make_request(q
, blk_queue_bio
);
869 q
->sg_reserved_size
= INT_MAX
;
871 /* Protect q->elevator from elevator_change */
872 mutex_lock(&q
->sysfs_lock
);
875 if (elevator_init(q
, NULL
)) {
876 mutex_unlock(&q
->sysfs_lock
);
880 mutex_unlock(&q
->sysfs_lock
);
885 blk_free_flush_queue(q
->fq
);
889 EXPORT_SYMBOL(blk_init_allocated_queue
);
891 bool blk_get_queue(struct request_queue
*q
)
893 if (likely(!blk_queue_dying(q
))) {
900 EXPORT_SYMBOL(blk_get_queue
);
902 static inline void blk_free_request(struct request_list
*rl
, struct request
*rq
)
904 if (rq
->rq_flags
& RQF_ELVPRIV
) {
905 elv_put_request(rl
->q
, rq
);
907 put_io_context(rq
->elv
.icq
->ioc
);
910 mempool_free(rq
, rl
->rq_pool
);
914 * ioc_batching returns true if the ioc is a valid batching request and
915 * should be given priority access to a request.
917 static inline int ioc_batching(struct request_queue
*q
, struct io_context
*ioc
)
923 * Make sure the process is able to allocate at least 1 request
924 * even if the batch times out, otherwise we could theoretically
927 return ioc
->nr_batch_requests
== q
->nr_batching
||
928 (ioc
->nr_batch_requests
> 0
929 && time_before(jiffies
, ioc
->last_waited
+ BLK_BATCH_TIME
));
933 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
934 * will cause the process to be a "batcher" on all queues in the system. This
935 * is the behaviour we want though - once it gets a wakeup it should be given
938 static void ioc_set_batching(struct request_queue
*q
, struct io_context
*ioc
)
940 if (!ioc
|| ioc_batching(q
, ioc
))
943 ioc
->nr_batch_requests
= q
->nr_batching
;
944 ioc
->last_waited
= jiffies
;
947 static void __freed_request(struct request_list
*rl
, int sync
)
949 struct request_queue
*q
= rl
->q
;
951 if (rl
->count
[sync
] < queue_congestion_off_threshold(q
))
952 blk_clear_congested(rl
, sync
);
954 if (rl
->count
[sync
] + 1 <= q
->nr_requests
) {
955 if (waitqueue_active(&rl
->wait
[sync
]))
956 wake_up(&rl
->wait
[sync
]);
958 blk_clear_rl_full(rl
, sync
);
963 * A request has just been released. Account for it, update the full and
964 * congestion status, wake up any waiters. Called under q->queue_lock.
966 static void freed_request(struct request_list
*rl
, bool sync
,
967 req_flags_t rq_flags
)
969 struct request_queue
*q
= rl
->q
;
973 if (rq_flags
& RQF_ELVPRIV
)
976 __freed_request(rl
, sync
);
978 if (unlikely(rl
->starved
[sync
^ 1]))
979 __freed_request(rl
, sync
^ 1);
982 int blk_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
984 struct request_list
*rl
;
985 int on_thresh
, off_thresh
;
987 spin_lock_irq(q
->queue_lock
);
989 blk_queue_congestion_threshold(q
);
990 on_thresh
= queue_congestion_on_threshold(q
);
991 off_thresh
= queue_congestion_off_threshold(q
);
993 blk_queue_for_each_rl(rl
, q
) {
994 if (rl
->count
[BLK_RW_SYNC
] >= on_thresh
)
995 blk_set_congested(rl
, BLK_RW_SYNC
);
996 else if (rl
->count
[BLK_RW_SYNC
] < off_thresh
)
997 blk_clear_congested(rl
, BLK_RW_SYNC
);
999 if (rl
->count
[BLK_RW_ASYNC
] >= on_thresh
)
1000 blk_set_congested(rl
, BLK_RW_ASYNC
);
1001 else if (rl
->count
[BLK_RW_ASYNC
] < off_thresh
)
1002 blk_clear_congested(rl
, BLK_RW_ASYNC
);
1004 if (rl
->count
[BLK_RW_SYNC
] >= q
->nr_requests
) {
1005 blk_set_rl_full(rl
, BLK_RW_SYNC
);
1007 blk_clear_rl_full(rl
, BLK_RW_SYNC
);
1008 wake_up(&rl
->wait
[BLK_RW_SYNC
]);
1011 if (rl
->count
[BLK_RW_ASYNC
] >= q
->nr_requests
) {
1012 blk_set_rl_full(rl
, BLK_RW_ASYNC
);
1014 blk_clear_rl_full(rl
, BLK_RW_ASYNC
);
1015 wake_up(&rl
->wait
[BLK_RW_ASYNC
]);
1019 spin_unlock_irq(q
->queue_lock
);
1024 * Determine if elevator data should be initialized when allocating the
1025 * request associated with @bio.
1027 static bool blk_rq_should_init_elevator(struct bio
*bio
)
1033 * Flush requests do not use the elevator so skip initialization.
1034 * This allows a request to share the flush and elevator data.
1036 if (bio
->bi_opf
& (REQ_PREFLUSH
| REQ_FUA
))
1043 * rq_ioc - determine io_context for request allocation
1044 * @bio: request being allocated is for this bio (can be %NULL)
1046 * Determine io_context to use for request allocation for @bio. May return
1047 * %NULL if %current->io_context doesn't exist.
1049 static struct io_context
*rq_ioc(struct bio
*bio
)
1051 #ifdef CONFIG_BLK_CGROUP
1052 if (bio
&& bio
->bi_ioc
)
1055 return current
->io_context
;
1059 * __get_request - get a free request
1060 * @rl: request list to allocate from
1061 * @op: operation and flags
1062 * @bio: bio to allocate request for (can be %NULL)
1063 * @gfp_mask: allocation mask
1065 * Get a free request from @q. This function may fail under memory
1066 * pressure or if @q is dead.
1068 * Must be called with @q->queue_lock held and,
1069 * Returns ERR_PTR on failure, with @q->queue_lock held.
1070 * Returns request pointer on success, with @q->queue_lock *not held*.
1072 static struct request
*__get_request(struct request_list
*rl
, unsigned int op
,
1073 struct bio
*bio
, gfp_t gfp_mask
)
1075 struct request_queue
*q
= rl
->q
;
1077 struct elevator_type
*et
= q
->elevator
->type
;
1078 struct io_context
*ioc
= rq_ioc(bio
);
1079 struct io_cq
*icq
= NULL
;
1080 const bool is_sync
= op_is_sync(op
);
1082 req_flags_t rq_flags
= RQF_ALLOCED
;
1084 if (unlikely(blk_queue_dying(q
)))
1085 return ERR_PTR(-ENODEV
);
1087 may_queue
= elv_may_queue(q
, op
);
1088 if (may_queue
== ELV_MQUEUE_NO
)
1091 if (rl
->count
[is_sync
]+1 >= queue_congestion_on_threshold(q
)) {
1092 if (rl
->count
[is_sync
]+1 >= q
->nr_requests
) {
1094 * The queue will fill after this allocation, so set
1095 * it as full, and mark this process as "batching".
1096 * This process will be allowed to complete a batch of
1097 * requests, others will be blocked.
1099 if (!blk_rl_full(rl
, is_sync
)) {
1100 ioc_set_batching(q
, ioc
);
1101 blk_set_rl_full(rl
, is_sync
);
1103 if (may_queue
!= ELV_MQUEUE_MUST
1104 && !ioc_batching(q
, ioc
)) {
1106 * The queue is full and the allocating
1107 * process is not a "batcher", and not
1108 * exempted by the IO scheduler
1110 return ERR_PTR(-ENOMEM
);
1114 blk_set_congested(rl
, is_sync
);
1118 * Only allow batching queuers to allocate up to 50% over the defined
1119 * limit of requests, otherwise we could have thousands of requests
1120 * allocated with any setting of ->nr_requests
1122 if (rl
->count
[is_sync
] >= (3 * q
->nr_requests
/ 2))
1123 return ERR_PTR(-ENOMEM
);
1125 q
->nr_rqs
[is_sync
]++;
1126 rl
->count
[is_sync
]++;
1127 rl
->starved
[is_sync
] = 0;
1130 * Decide whether the new request will be managed by elevator. If
1131 * so, mark @rq_flags and increment elvpriv. Non-zero elvpriv will
1132 * prevent the current elevator from being destroyed until the new
1133 * request is freed. This guarantees icq's won't be destroyed and
1134 * makes creating new ones safe.
1136 * Also, lookup icq while holding queue_lock. If it doesn't exist,
1137 * it will be created after releasing queue_lock.
1139 if (blk_rq_should_init_elevator(bio
) && !blk_queue_bypass(q
)) {
1140 rq_flags
|= RQF_ELVPRIV
;
1141 q
->nr_rqs_elvpriv
++;
1142 if (et
->icq_cache
&& ioc
)
1143 icq
= ioc_lookup_icq(ioc
, q
);
1146 if (blk_queue_io_stat(q
))
1147 rq_flags
|= RQF_IO_STAT
;
1148 spin_unlock_irq(q
->queue_lock
);
1150 /* allocate and init request */
1151 rq
= mempool_alloc(rl
->rq_pool
, gfp_mask
);
1156 blk_rq_set_rl(rq
, rl
);
1158 rq
->rq_flags
= rq_flags
;
1161 if (rq_flags
& RQF_ELVPRIV
) {
1162 if (unlikely(et
->icq_cache
&& !icq
)) {
1164 icq
= ioc_create_icq(ioc
, q
, gfp_mask
);
1170 if (unlikely(elv_set_request(q
, rq
, bio
, gfp_mask
)))
1173 /* @rq->elv.icq holds io_context until @rq is freed */
1175 get_io_context(icq
->ioc
);
1179 * ioc may be NULL here, and ioc_batching will be false. That's
1180 * OK, if the queue is under the request limit then requests need
1181 * not count toward the nr_batch_requests limit. There will always
1182 * be some limit enforced by BLK_BATCH_TIME.
1184 if (ioc_batching(q
, ioc
))
1185 ioc
->nr_batch_requests
--;
1187 trace_block_getrq(q
, bio
, op
);
1192 * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed
1193 * and may fail indefinitely under memory pressure and thus
1194 * shouldn't stall IO. Treat this request as !elvpriv. This will
1195 * disturb iosched and blkcg but weird is bettern than dead.
1197 printk_ratelimited(KERN_WARNING
"%s: dev %s: request aux data allocation failed, iosched may be disturbed\n",
1198 __func__
, dev_name(q
->backing_dev_info
.dev
));
1200 rq
->rq_flags
&= ~RQF_ELVPRIV
;
1203 spin_lock_irq(q
->queue_lock
);
1204 q
->nr_rqs_elvpriv
--;
1205 spin_unlock_irq(q
->queue_lock
);
1210 * Allocation failed presumably due to memory. Undo anything we
1211 * might have messed up.
1213 * Allocating task should really be put onto the front of the wait
1214 * queue, but this is pretty rare.
1216 spin_lock_irq(q
->queue_lock
);
1217 freed_request(rl
, is_sync
, rq_flags
);
1220 * in the very unlikely event that allocation failed and no
1221 * requests for this direction was pending, mark us starved so that
1222 * freeing of a request in the other direction will notice
1223 * us. another possible fix would be to split the rq mempool into
1227 if (unlikely(rl
->count
[is_sync
] == 0))
1228 rl
->starved
[is_sync
] = 1;
1229 return ERR_PTR(-ENOMEM
);
1233 * get_request - get a free request
1234 * @q: request_queue to allocate request from
1235 * @op: operation and flags
1236 * @bio: bio to allocate request for (can be %NULL)
1237 * @gfp_mask: allocation mask
1239 * Get a free request from @q. If %__GFP_DIRECT_RECLAIM is set in @gfp_mask,
1240 * this function keeps retrying under memory pressure and fails iff @q is dead.
1242 * Must be called with @q->queue_lock held and,
1243 * Returns ERR_PTR on failure, with @q->queue_lock held.
1244 * Returns request pointer on success, with @q->queue_lock *not held*.
1246 static struct request
*get_request(struct request_queue
*q
, unsigned int op
,
1247 struct bio
*bio
, gfp_t gfp_mask
)
1249 const bool is_sync
= op_is_sync(op
);
1251 struct request_list
*rl
;
1254 rl
= blk_get_rl(q
, bio
); /* transferred to @rq on success */
1256 rq
= __get_request(rl
, op
, bio
, gfp_mask
);
1260 if (!gfpflags_allow_blocking(gfp_mask
) || unlikely(blk_queue_dying(q
))) {
1265 /* wait on @rl and retry */
1266 prepare_to_wait_exclusive(&rl
->wait
[is_sync
], &wait
,
1267 TASK_UNINTERRUPTIBLE
);
1269 trace_block_sleeprq(q
, bio
, op
);
1271 spin_unlock_irq(q
->queue_lock
);
1275 * After sleeping, we become a "batching" process and will be able
1276 * to allocate at least one request, and up to a big batch of them
1277 * for a small period time. See ioc_batching, ioc_set_batching
1279 ioc_set_batching(q
, current
->io_context
);
1281 spin_lock_irq(q
->queue_lock
);
1282 finish_wait(&rl
->wait
[is_sync
], &wait
);
1287 static struct request
*blk_old_get_request(struct request_queue
*q
, int rw
,
1292 BUG_ON(rw
!= READ
&& rw
!= WRITE
);
1294 /* create ioc upfront */
1295 create_io_context(gfp_mask
, q
->node
);
1297 spin_lock_irq(q
->queue_lock
);
1298 rq
= get_request(q
, rw
, NULL
, gfp_mask
);
1300 spin_unlock_irq(q
->queue_lock
);
1304 /* q->queue_lock is unlocked at this point */
1306 rq
->__sector
= (sector_t
) -1;
1307 rq
->bio
= rq
->biotail
= NULL
;
1311 struct request
*blk_get_request(struct request_queue
*q
, int rw
, gfp_t gfp_mask
)
1314 return blk_mq_alloc_request(q
, rw
,
1315 (gfp_mask
& __GFP_DIRECT_RECLAIM
) ?
1316 0 : BLK_MQ_REQ_NOWAIT
);
1318 return blk_old_get_request(q
, rw
, gfp_mask
);
1320 EXPORT_SYMBOL(blk_get_request
);
1323 * blk_rq_set_block_pc - initialize a request to type BLOCK_PC
1324 * @rq: request to be initialized
1327 void blk_rq_set_block_pc(struct request
*rq
)
1329 rq
->cmd_type
= REQ_TYPE_BLOCK_PC
;
1330 memset(rq
->__cmd
, 0, sizeof(rq
->__cmd
));
1332 EXPORT_SYMBOL(blk_rq_set_block_pc
);
1335 * blk_requeue_request - put a request back on queue
1336 * @q: request queue where request should be inserted
1337 * @rq: request to be inserted
1340 * Drivers often keep queueing requests until the hardware cannot accept
1341 * more, when that condition happens we need to put the request back
1342 * on the queue. Must be called with queue lock held.
1344 void blk_requeue_request(struct request_queue
*q
, struct request
*rq
)
1346 blk_delete_timer(rq
);
1347 blk_clear_rq_complete(rq
);
1348 trace_block_rq_requeue(q
, rq
);
1349 wbt_requeue(q
->rq_wb
, &rq
->issue_stat
);
1351 if (rq
->rq_flags
& RQF_QUEUED
)
1352 blk_queue_end_tag(q
, rq
);
1354 BUG_ON(blk_queued_rq(rq
));
1356 elv_requeue_request(q
, rq
);
1358 EXPORT_SYMBOL(blk_requeue_request
);
1360 static void add_acct_request(struct request_queue
*q
, struct request
*rq
,
1363 blk_account_io_start(rq
, true);
1364 __elv_add_request(q
, rq
, where
);
1367 static void part_round_stats_single(int cpu
, struct hd_struct
*part
,
1372 if (now
== part
->stamp
)
1375 inflight
= part_in_flight(part
);
1377 __part_stat_add(cpu
, part
, time_in_queue
,
1378 inflight
* (now
- part
->stamp
));
1379 __part_stat_add(cpu
, part
, io_ticks
, (now
- part
->stamp
));
1385 * part_round_stats() - Round off the performance stats on a struct disk_stats.
1386 * @cpu: cpu number for stats access
1387 * @part: target partition
1389 * The average IO queue length and utilisation statistics are maintained
1390 * by observing the current state of the queue length and the amount of
1391 * time it has been in this state for.
1393 * Normally, that accounting is done on IO completion, but that can result
1394 * in more than a second's worth of IO being accounted for within any one
1395 * second, leading to >100% utilisation. To deal with that, we call this
1396 * function to do a round-off before returning the results when reading
1397 * /proc/diskstats. This accounts immediately for all queue usage up to
1398 * the current jiffies and restarts the counters again.
1400 void part_round_stats(int cpu
, struct hd_struct
*part
)
1402 unsigned long now
= jiffies
;
1405 part_round_stats_single(cpu
, &part_to_disk(part
)->part0
, now
);
1406 part_round_stats_single(cpu
, part
, now
);
1408 EXPORT_SYMBOL_GPL(part_round_stats
);
1411 static void blk_pm_put_request(struct request
*rq
)
1413 if (rq
->q
->dev
&& !(rq
->rq_flags
& RQF_PM
) && !--rq
->q
->nr_pending
)
1414 pm_runtime_mark_last_busy(rq
->q
->dev
);
1417 static inline void blk_pm_put_request(struct request
*rq
) {}
1421 * queue lock must be held
1423 void __blk_put_request(struct request_queue
*q
, struct request
*req
)
1425 req_flags_t rq_flags
= req
->rq_flags
;
1431 blk_mq_free_request(req
);
1435 blk_pm_put_request(req
);
1437 elv_completed_request(q
, req
);
1439 /* this is a bio leak */
1440 WARN_ON(req
->bio
!= NULL
);
1442 wbt_done(q
->rq_wb
, &req
->issue_stat
);
1445 * Request may not have originated from ll_rw_blk. if not,
1446 * it didn't come out of our reserved rq pools
1448 if (rq_flags
& RQF_ALLOCED
) {
1449 struct request_list
*rl
= blk_rq_rl(req
);
1450 bool sync
= op_is_sync(req
->cmd_flags
);
1452 BUG_ON(!list_empty(&req
->queuelist
));
1453 BUG_ON(ELV_ON_HASH(req
));
1455 blk_free_request(rl
, req
);
1456 freed_request(rl
, sync
, rq_flags
);
1460 EXPORT_SYMBOL_GPL(__blk_put_request
);
1462 void blk_put_request(struct request
*req
)
1464 struct request_queue
*q
= req
->q
;
1467 blk_mq_free_request(req
);
1469 unsigned long flags
;
1471 spin_lock_irqsave(q
->queue_lock
, flags
);
1472 __blk_put_request(q
, req
);
1473 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1476 EXPORT_SYMBOL(blk_put_request
);
1479 * blk_add_request_payload - add a payload to a request
1480 * @rq: request to update
1481 * @page: page backing the payload
1482 * @offset: offset in page
1483 * @len: length of the payload.
1485 * This allows to later add a payload to an already submitted request by
1486 * a block driver. The driver needs to take care of freeing the payload
1489 * Note that this is a quite horrible hack and nothing but handling of
1490 * discard requests should ever use it.
1492 void blk_add_request_payload(struct request
*rq
, struct page
*page
,
1493 int offset
, unsigned int len
)
1495 struct bio
*bio
= rq
->bio
;
1497 bio
->bi_io_vec
->bv_page
= page
;
1498 bio
->bi_io_vec
->bv_offset
= offset
;
1499 bio
->bi_io_vec
->bv_len
= len
;
1501 bio
->bi_iter
.bi_size
= len
;
1503 bio
->bi_phys_segments
= 1;
1505 rq
->__data_len
= rq
->resid_len
= len
;
1506 rq
->nr_phys_segments
= 1;
1508 EXPORT_SYMBOL_GPL(blk_add_request_payload
);
1510 bool bio_attempt_back_merge(struct request_queue
*q
, struct request
*req
,
1513 const int ff
= bio
->bi_opf
& REQ_FAILFAST_MASK
;
1515 if (!ll_back_merge_fn(q
, req
, bio
))
1518 trace_block_bio_backmerge(q
, req
, bio
);
1520 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
1521 blk_rq_set_mixed_merge(req
);
1523 req
->biotail
->bi_next
= bio
;
1525 req
->__data_len
+= bio
->bi_iter
.bi_size
;
1526 req
->ioprio
= ioprio_best(req
->ioprio
, bio_prio(bio
));
1528 blk_account_io_start(req
, false);
1532 bool bio_attempt_front_merge(struct request_queue
*q
, struct request
*req
,
1535 const int ff
= bio
->bi_opf
& REQ_FAILFAST_MASK
;
1537 if (!ll_front_merge_fn(q
, req
, bio
))
1540 trace_block_bio_frontmerge(q
, req
, bio
);
1542 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
1543 blk_rq_set_mixed_merge(req
);
1545 bio
->bi_next
= req
->bio
;
1548 req
->__sector
= bio
->bi_iter
.bi_sector
;
1549 req
->__data_len
+= bio
->bi_iter
.bi_size
;
1550 req
->ioprio
= ioprio_best(req
->ioprio
, bio_prio(bio
));
1552 blk_account_io_start(req
, false);
1557 * blk_attempt_plug_merge - try to merge with %current's plugged list
1558 * @q: request_queue new bio is being queued at
1559 * @bio: new bio being queued
1560 * @request_count: out parameter for number of traversed plugged requests
1561 * @same_queue_rq: pointer to &struct request that gets filled in when
1562 * another request associated with @q is found on the plug list
1563 * (optional, may be %NULL)
1565 * Determine whether @bio being queued on @q can be merged with a request
1566 * on %current's plugged list. Returns %true if merge was successful,
1569 * Plugging coalesces IOs from the same issuer for the same purpose without
1570 * going through @q->queue_lock. As such it's more of an issuing mechanism
1571 * than scheduling, and the request, while may have elvpriv data, is not
1572 * added on the elevator at this point. In addition, we don't have
1573 * reliable access to the elevator outside queue lock. Only check basic
1574 * merging parameters without querying the elevator.
1576 * Caller must ensure !blk_queue_nomerges(q) beforehand.
1578 bool blk_attempt_plug_merge(struct request_queue
*q
, struct bio
*bio
,
1579 unsigned int *request_count
,
1580 struct request
**same_queue_rq
)
1582 struct blk_plug
*plug
;
1585 struct list_head
*plug_list
;
1587 plug
= current
->plug
;
1593 plug_list
= &plug
->mq_list
;
1595 plug_list
= &plug
->list
;
1597 list_for_each_entry_reverse(rq
, plug_list
, queuelist
) {
1603 * Only blk-mq multiple hardware queues case checks the
1604 * rq in the same queue, there should be only one such
1608 *same_queue_rq
= rq
;
1611 if (rq
->q
!= q
|| !blk_rq_merge_ok(rq
, bio
))
1614 el_ret
= blk_try_merge(rq
, bio
);
1615 if (el_ret
== ELEVATOR_BACK_MERGE
) {
1616 ret
= bio_attempt_back_merge(q
, rq
, bio
);
1619 } else if (el_ret
== ELEVATOR_FRONT_MERGE
) {
1620 ret
= bio_attempt_front_merge(q
, rq
, bio
);
1629 unsigned int blk_plug_queued_count(struct request_queue
*q
)
1631 struct blk_plug
*plug
;
1633 struct list_head
*plug_list
;
1634 unsigned int ret
= 0;
1636 plug
= current
->plug
;
1641 plug_list
= &plug
->mq_list
;
1643 plug_list
= &plug
->list
;
1645 list_for_each_entry(rq
, plug_list
, queuelist
) {
1653 void init_request_from_bio(struct request
*req
, struct bio
*bio
)
1655 req
->cmd_type
= REQ_TYPE_FS
;
1656 if (bio
->bi_opf
& REQ_RAHEAD
)
1657 req
->cmd_flags
|= REQ_FAILFAST_MASK
;
1660 req
->__sector
= bio
->bi_iter
.bi_sector
;
1661 req
->ioprio
= bio_prio(bio
);
1662 blk_rq_bio_prep(req
->q
, req
, bio
);
1665 static blk_qc_t
blk_queue_bio(struct request_queue
*q
, struct bio
*bio
)
1667 struct blk_plug
*plug
;
1668 int el_ret
, where
= ELEVATOR_INSERT_SORT
;
1669 struct request
*req
;
1670 unsigned int request_count
= 0;
1671 unsigned int wb_acct
;
1674 * low level driver can indicate that it wants pages above a
1675 * certain limit bounced to low memory (ie for highmem, or even
1676 * ISA dma in theory)
1678 blk_queue_bounce(q
, &bio
);
1680 blk_queue_split(q
, &bio
, q
->bio_split
);
1682 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1683 bio
->bi_error
= -EIO
;
1685 return BLK_QC_T_NONE
;
1688 if (bio
->bi_opf
& (REQ_PREFLUSH
| REQ_FUA
)) {
1689 spin_lock_irq(q
->queue_lock
);
1690 where
= ELEVATOR_INSERT_FLUSH
;
1695 * Check if we can merge with the plugged list before grabbing
1698 if (!blk_queue_nomerges(q
)) {
1699 if (blk_attempt_plug_merge(q
, bio
, &request_count
, NULL
))
1700 return BLK_QC_T_NONE
;
1702 request_count
= blk_plug_queued_count(q
);
1704 spin_lock_irq(q
->queue_lock
);
1706 el_ret
= elv_merge(q
, &req
, bio
);
1707 if (el_ret
== ELEVATOR_BACK_MERGE
) {
1708 if (bio_attempt_back_merge(q
, req
, bio
)) {
1709 elv_bio_merged(q
, req
, bio
);
1710 if (!attempt_back_merge(q
, req
))
1711 elv_merged_request(q
, req
, el_ret
);
1714 } else if (el_ret
== ELEVATOR_FRONT_MERGE
) {
1715 if (bio_attempt_front_merge(q
, req
, bio
)) {
1716 elv_bio_merged(q
, req
, bio
);
1717 if (!attempt_front_merge(q
, req
))
1718 elv_merged_request(q
, req
, el_ret
);
1724 wb_acct
= wbt_wait(q
->rq_wb
, bio
, q
->queue_lock
);
1727 * Grab a free request. This is might sleep but can not fail.
1728 * Returns with the queue unlocked.
1730 req
= get_request(q
, bio
->bi_opf
, bio
, GFP_NOIO
);
1732 __wbt_done(q
->rq_wb
, wb_acct
);
1733 bio
->bi_error
= PTR_ERR(req
);
1738 wbt_track(&req
->issue_stat
, wb_acct
);
1741 * After dropping the lock and possibly sleeping here, our request
1742 * may now be mergeable after it had proven unmergeable (above).
1743 * We don't worry about that case for efficiency. It won't happen
1744 * often, and the elevators are able to handle it.
1746 init_request_from_bio(req
, bio
);
1748 if (test_bit(QUEUE_FLAG_SAME_COMP
, &q
->queue_flags
))
1749 req
->cpu
= raw_smp_processor_id();
1751 plug
= current
->plug
;
1754 * If this is the first request added after a plug, fire
1758 trace_block_plug(q
);
1760 struct request
*last
= list_entry_rq(plug
->list
.prev
);
1761 if (request_count
>= BLK_MAX_REQUEST_COUNT
||
1762 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
) {
1763 blk_flush_plug_list(plug
, false);
1764 trace_block_plug(q
);
1767 list_add_tail(&req
->queuelist
, &plug
->list
);
1768 blk_account_io_start(req
, true);
1770 spin_lock_irq(q
->queue_lock
);
1771 add_acct_request(q
, req
, where
);
1774 spin_unlock_irq(q
->queue_lock
);
1777 return BLK_QC_T_NONE
;
1781 * If bio->bi_dev is a partition, remap the location
1783 static inline void blk_partition_remap(struct bio
*bio
)
1785 struct block_device
*bdev
= bio
->bi_bdev
;
1787 if (bio_sectors(bio
) && bdev
!= bdev
->bd_contains
) {
1788 struct hd_struct
*p
= bdev
->bd_part
;
1790 bio
->bi_iter
.bi_sector
+= p
->start_sect
;
1791 bio
->bi_bdev
= bdev
->bd_contains
;
1793 trace_block_bio_remap(bdev_get_queue(bio
->bi_bdev
), bio
,
1795 bio
->bi_iter
.bi_sector
- p
->start_sect
);
1799 static void handle_bad_sector(struct bio
*bio
)
1801 char b
[BDEVNAME_SIZE
];
1803 printk(KERN_INFO
"attempt to access beyond end of device\n");
1804 printk(KERN_INFO
"%s: rw=%d, want=%Lu, limit=%Lu\n",
1805 bdevname(bio
->bi_bdev
, b
),
1807 (unsigned long long)bio_end_sector(bio
),
1808 (long long)(i_size_read(bio
->bi_bdev
->bd_inode
) >> 9));
1811 #ifdef CONFIG_FAIL_MAKE_REQUEST
1813 static DECLARE_FAULT_ATTR(fail_make_request
);
1815 static int __init
setup_fail_make_request(char *str
)
1817 return setup_fault_attr(&fail_make_request
, str
);
1819 __setup("fail_make_request=", setup_fail_make_request
);
1821 static bool should_fail_request(struct hd_struct
*part
, unsigned int bytes
)
1823 return part
->make_it_fail
&& should_fail(&fail_make_request
, bytes
);
1826 static int __init
fail_make_request_debugfs(void)
1828 struct dentry
*dir
= fault_create_debugfs_attr("fail_make_request",
1829 NULL
, &fail_make_request
);
1831 return PTR_ERR_OR_ZERO(dir
);
1834 late_initcall(fail_make_request_debugfs
);
1836 #else /* CONFIG_FAIL_MAKE_REQUEST */
1838 static inline bool should_fail_request(struct hd_struct
*part
,
1844 #endif /* CONFIG_FAIL_MAKE_REQUEST */
1847 * Check whether this bio extends beyond the end of the device.
1849 static inline int bio_check_eod(struct bio
*bio
, unsigned int nr_sectors
)
1856 /* Test device or partition size, when known. */
1857 maxsector
= i_size_read(bio
->bi_bdev
->bd_inode
) >> 9;
1859 sector_t sector
= bio
->bi_iter
.bi_sector
;
1861 if (maxsector
< nr_sectors
|| maxsector
- nr_sectors
< sector
) {
1863 * This may well happen - the kernel calls bread()
1864 * without checking the size of the device, e.g., when
1865 * mounting a device.
1867 handle_bad_sector(bio
);
1875 static noinline_for_stack
bool
1876 generic_make_request_checks(struct bio
*bio
)
1878 struct request_queue
*q
;
1879 int nr_sectors
= bio_sectors(bio
);
1881 char b
[BDEVNAME_SIZE
];
1882 struct hd_struct
*part
;
1886 if (bio_check_eod(bio
, nr_sectors
))
1889 q
= bdev_get_queue(bio
->bi_bdev
);
1892 "generic_make_request: Trying to access "
1893 "nonexistent block-device %s (%Lu)\n",
1894 bdevname(bio
->bi_bdev
, b
),
1895 (long long) bio
->bi_iter
.bi_sector
);
1899 part
= bio
->bi_bdev
->bd_part
;
1900 if (should_fail_request(part
, bio
->bi_iter
.bi_size
) ||
1901 should_fail_request(&part_to_disk(part
)->part0
,
1902 bio
->bi_iter
.bi_size
))
1906 * If this device has partitions, remap block n
1907 * of partition p to block n+start(p) of the disk.
1909 blk_partition_remap(bio
);
1911 if (bio_check_eod(bio
, nr_sectors
))
1915 * Filter flush bio's early so that make_request based
1916 * drivers without flush support don't have to worry
1919 if ((bio
->bi_opf
& (REQ_PREFLUSH
| REQ_FUA
)) &&
1920 !test_bit(QUEUE_FLAG_WC
, &q
->queue_flags
)) {
1921 bio
->bi_opf
&= ~(REQ_PREFLUSH
| REQ_FUA
);
1928 switch (bio_op(bio
)) {
1929 case REQ_OP_DISCARD
:
1930 if (!blk_queue_discard(q
))
1933 case REQ_OP_SECURE_ERASE
:
1934 if (!blk_queue_secure_erase(q
))
1937 case REQ_OP_WRITE_SAME
:
1938 if (!bdev_write_same(bio
->bi_bdev
))
1940 case REQ_OP_ZONE_REPORT
:
1941 case REQ_OP_ZONE_RESET
:
1942 if (!bdev_is_zoned(bio
->bi_bdev
))
1950 * Various block parts want %current->io_context and lazy ioc
1951 * allocation ends up trading a lot of pain for a small amount of
1952 * memory. Just allocate it upfront. This may fail and block
1953 * layer knows how to live with it.
1955 create_io_context(GFP_ATOMIC
, q
->node
);
1957 if (!blkcg_bio_issue_check(q
, bio
))
1960 trace_block_bio_queue(q
, bio
);
1966 bio
->bi_error
= err
;
1972 * generic_make_request - hand a buffer to its device driver for I/O
1973 * @bio: The bio describing the location in memory and on the device.
1975 * generic_make_request() is used to make I/O requests of block
1976 * devices. It is passed a &struct bio, which describes the I/O that needs
1979 * generic_make_request() does not return any status. The
1980 * success/failure status of the request, along with notification of
1981 * completion, is delivered asynchronously through the bio->bi_end_io
1982 * function described (one day) else where.
1984 * The caller of generic_make_request must make sure that bi_io_vec
1985 * are set to describe the memory buffer, and that bi_dev and bi_sector are
1986 * set to describe the device address, and the
1987 * bi_end_io and optionally bi_private are set to describe how
1988 * completion notification should be signaled.
1990 * generic_make_request and the drivers it calls may use bi_next if this
1991 * bio happens to be merged with someone else, and may resubmit the bio to
1992 * a lower device by calling into generic_make_request recursively, which
1993 * means the bio should NOT be touched after the call to ->make_request_fn.
1995 blk_qc_t
generic_make_request(struct bio
*bio
)
1997 struct bio_list bio_list_on_stack
;
1998 blk_qc_t ret
= BLK_QC_T_NONE
;
2000 if (!generic_make_request_checks(bio
))
2004 * We only want one ->make_request_fn to be active at a time, else
2005 * stack usage with stacked devices could be a problem. So use
2006 * current->bio_list to keep a list of requests submited by a
2007 * make_request_fn function. current->bio_list is also used as a
2008 * flag to say if generic_make_request is currently active in this
2009 * task or not. If it is NULL, then no make_request is active. If
2010 * it is non-NULL, then a make_request is active, and new requests
2011 * should be added at the tail
2013 if (current
->bio_list
) {
2014 bio_list_add(current
->bio_list
, bio
);
2018 /* following loop may be a bit non-obvious, and so deserves some
2020 * Before entering the loop, bio->bi_next is NULL (as all callers
2021 * ensure that) so we have a list with a single bio.
2022 * We pretend that we have just taken it off a longer list, so
2023 * we assign bio_list to a pointer to the bio_list_on_stack,
2024 * thus initialising the bio_list of new bios to be
2025 * added. ->make_request() may indeed add some more bios
2026 * through a recursive call to generic_make_request. If it
2027 * did, we find a non-NULL value in bio_list and re-enter the loop
2028 * from the top. In this case we really did just take the bio
2029 * of the top of the list (no pretending) and so remove it from
2030 * bio_list, and call into ->make_request() again.
2032 BUG_ON(bio
->bi_next
);
2033 bio_list_init(&bio_list_on_stack
);
2034 current
->bio_list
= &bio_list_on_stack
;
2036 struct request_queue
*q
= bdev_get_queue(bio
->bi_bdev
);
2038 if (likely(blk_queue_enter(q
, false) == 0)) {
2039 ret
= q
->make_request_fn(q
, bio
);
2043 bio
= bio_list_pop(current
->bio_list
);
2045 struct bio
*bio_next
= bio_list_pop(current
->bio_list
);
2051 current
->bio_list
= NULL
; /* deactivate */
2056 EXPORT_SYMBOL(generic_make_request
);
2059 * submit_bio - submit a bio to the block device layer for I/O
2060 * @bio: The &struct bio which describes the I/O
2062 * submit_bio() is very similar in purpose to generic_make_request(), and
2063 * uses that function to do most of the work. Both are fairly rough
2064 * interfaces; @bio must be presetup and ready for I/O.
2067 blk_qc_t
submit_bio(struct bio
*bio
)
2070 * If it's a regular read/write or a barrier with data attached,
2071 * go through the normal accounting stuff before submission.
2073 if (bio_has_data(bio
)) {
2076 if (unlikely(bio_op(bio
) == REQ_OP_WRITE_SAME
))
2077 count
= bdev_logical_block_size(bio
->bi_bdev
) >> 9;
2079 count
= bio_sectors(bio
);
2081 if (op_is_write(bio_op(bio
))) {
2082 count_vm_events(PGPGOUT
, count
);
2084 task_io_account_read(bio
->bi_iter
.bi_size
);
2085 count_vm_events(PGPGIN
, count
);
2088 if (unlikely(block_dump
)) {
2089 char b
[BDEVNAME_SIZE
];
2090 printk(KERN_DEBUG
"%s(%d): %s block %Lu on %s (%u sectors)\n",
2091 current
->comm
, task_pid_nr(current
),
2092 op_is_write(bio_op(bio
)) ? "WRITE" : "READ",
2093 (unsigned long long)bio
->bi_iter
.bi_sector
,
2094 bdevname(bio
->bi_bdev
, b
),
2099 return generic_make_request(bio
);
2101 EXPORT_SYMBOL(submit_bio
);
2104 * blk_cloned_rq_check_limits - Helper function to check a cloned request
2105 * for new the queue limits
2107 * @rq: the request being checked
2110 * @rq may have been made based on weaker limitations of upper-level queues
2111 * in request stacking drivers, and it may violate the limitation of @q.
2112 * Since the block layer and the underlying device driver trust @rq
2113 * after it is inserted to @q, it should be checked against @q before
2114 * the insertion using this generic function.
2116 * Request stacking drivers like request-based dm may change the queue
2117 * limits when retrying requests on other queues. Those requests need
2118 * to be checked against the new queue limits again during dispatch.
2120 static int blk_cloned_rq_check_limits(struct request_queue
*q
,
2123 if (blk_rq_sectors(rq
) > blk_queue_get_max_sectors(q
, req_op(rq
))) {
2124 printk(KERN_ERR
"%s: over max size limit.\n", __func__
);
2129 * queue's settings related to segment counting like q->bounce_pfn
2130 * may differ from that of other stacking queues.
2131 * Recalculate it to check the request correctly on this queue's
2134 blk_recalc_rq_segments(rq
);
2135 if (rq
->nr_phys_segments
> queue_max_segments(q
)) {
2136 printk(KERN_ERR
"%s: over max segments limit.\n", __func__
);
2144 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
2145 * @q: the queue to submit the request
2146 * @rq: the request being queued
2148 int blk_insert_cloned_request(struct request_queue
*q
, struct request
*rq
)
2150 unsigned long flags
;
2151 int where
= ELEVATOR_INSERT_BACK
;
2153 if (blk_cloned_rq_check_limits(q
, rq
))
2157 should_fail_request(&rq
->rq_disk
->part0
, blk_rq_bytes(rq
)))
2161 if (blk_queue_io_stat(q
))
2162 blk_account_io_start(rq
, true);
2163 blk_mq_insert_request(rq
, false, true, false);
2167 spin_lock_irqsave(q
->queue_lock
, flags
);
2168 if (unlikely(blk_queue_dying(q
))) {
2169 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2174 * Submitting request must be dequeued before calling this function
2175 * because it will be linked to another request_queue
2177 BUG_ON(blk_queued_rq(rq
));
2179 if (rq
->cmd_flags
& (REQ_PREFLUSH
| REQ_FUA
))
2180 where
= ELEVATOR_INSERT_FLUSH
;
2182 add_acct_request(q
, rq
, where
);
2183 if (where
== ELEVATOR_INSERT_FLUSH
)
2185 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2189 EXPORT_SYMBOL_GPL(blk_insert_cloned_request
);
2192 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
2193 * @rq: request to examine
2196 * A request could be merge of IOs which require different failure
2197 * handling. This function determines the number of bytes which
2198 * can be failed from the beginning of the request without
2199 * crossing into area which need to be retried further.
2202 * The number of bytes to fail.
2205 * queue_lock must be held.
2207 unsigned int blk_rq_err_bytes(const struct request
*rq
)
2209 unsigned int ff
= rq
->cmd_flags
& REQ_FAILFAST_MASK
;
2210 unsigned int bytes
= 0;
2213 if (!(rq
->rq_flags
& RQF_MIXED_MERGE
))
2214 return blk_rq_bytes(rq
);
2217 * Currently the only 'mixing' which can happen is between
2218 * different fastfail types. We can safely fail portions
2219 * which have all the failfast bits that the first one has -
2220 * the ones which are at least as eager to fail as the first
2223 for (bio
= rq
->bio
; bio
; bio
= bio
->bi_next
) {
2224 if ((bio
->bi_opf
& ff
) != ff
)
2226 bytes
+= bio
->bi_iter
.bi_size
;
2229 /* this could lead to infinite loop */
2230 BUG_ON(blk_rq_bytes(rq
) && !bytes
);
2233 EXPORT_SYMBOL_GPL(blk_rq_err_bytes
);
2235 void blk_account_io_completion(struct request
*req
, unsigned int bytes
)
2237 if (blk_do_io_stat(req
)) {
2238 const int rw
= rq_data_dir(req
);
2239 struct hd_struct
*part
;
2242 cpu
= part_stat_lock();
2244 part_stat_add(cpu
, part
, sectors
[rw
], bytes
>> 9);
2249 void blk_account_io_done(struct request
*req
)
2252 * Account IO completion. flush_rq isn't accounted as a
2253 * normal IO on queueing nor completion. Accounting the
2254 * containing request is enough.
2256 if (blk_do_io_stat(req
) && !(req
->rq_flags
& RQF_FLUSH_SEQ
)) {
2257 unsigned long duration
= jiffies
- req
->start_time
;
2258 const int rw
= rq_data_dir(req
);
2259 struct hd_struct
*part
;
2262 cpu
= part_stat_lock();
2265 part_stat_inc(cpu
, part
, ios
[rw
]);
2266 part_stat_add(cpu
, part
, ticks
[rw
], duration
);
2267 part_round_stats(cpu
, part
);
2268 part_dec_in_flight(part
, rw
);
2270 hd_struct_put(part
);
2277 * Don't process normal requests when queue is suspended
2278 * or in the process of suspending/resuming
2280 static struct request
*blk_pm_peek_request(struct request_queue
*q
,
2283 if (q
->dev
&& (q
->rpm_status
== RPM_SUSPENDED
||
2284 (q
->rpm_status
!= RPM_ACTIVE
&& !(rq
->rq_flags
& RQF_PM
))))
2290 static inline struct request
*blk_pm_peek_request(struct request_queue
*q
,
2297 void blk_account_io_start(struct request
*rq
, bool new_io
)
2299 struct hd_struct
*part
;
2300 int rw
= rq_data_dir(rq
);
2303 if (!blk_do_io_stat(rq
))
2306 cpu
= part_stat_lock();
2310 part_stat_inc(cpu
, part
, merges
[rw
]);
2312 part
= disk_map_sector_rcu(rq
->rq_disk
, blk_rq_pos(rq
));
2313 if (!hd_struct_try_get(part
)) {
2315 * The partition is already being removed,
2316 * the request will be accounted on the disk only
2318 * We take a reference on disk->part0 although that
2319 * partition will never be deleted, so we can treat
2320 * it as any other partition.
2322 part
= &rq
->rq_disk
->part0
;
2323 hd_struct_get(part
);
2325 part_round_stats(cpu
, part
);
2326 part_inc_in_flight(part
, rw
);
2334 * blk_peek_request - peek at the top of a request queue
2335 * @q: request queue to peek at
2338 * Return the request at the top of @q. The returned request
2339 * should be started using blk_start_request() before LLD starts
2343 * Pointer to the request at the top of @q if available. Null
2347 * queue_lock must be held.
2349 struct request
*blk_peek_request(struct request_queue
*q
)
2354 while ((rq
= __elv_next_request(q
)) != NULL
) {
2356 rq
= blk_pm_peek_request(q
, rq
);
2360 if (!(rq
->rq_flags
& RQF_STARTED
)) {
2362 * This is the first time the device driver
2363 * sees this request (possibly after
2364 * requeueing). Notify IO scheduler.
2366 if (rq
->rq_flags
& RQF_SORTED
)
2367 elv_activate_rq(q
, rq
);
2370 * just mark as started even if we don't start
2371 * it, a request that has been delayed should
2372 * not be passed by new incoming requests
2374 rq
->rq_flags
|= RQF_STARTED
;
2375 trace_block_rq_issue(q
, rq
);
2378 if (!q
->boundary_rq
|| q
->boundary_rq
== rq
) {
2379 q
->end_sector
= rq_end_sector(rq
);
2380 q
->boundary_rq
= NULL
;
2383 if (rq
->rq_flags
& RQF_DONTPREP
)
2386 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
2388 * make sure space for the drain appears we
2389 * know we can do this because max_hw_segments
2390 * has been adjusted to be one fewer than the
2393 rq
->nr_phys_segments
++;
2399 ret
= q
->prep_rq_fn(q
, rq
);
2400 if (ret
== BLKPREP_OK
) {
2402 } else if (ret
== BLKPREP_DEFER
) {
2404 * the request may have been (partially) prepped.
2405 * we need to keep this request in the front to
2406 * avoid resource deadlock. RQF_STARTED will
2407 * prevent other fs requests from passing this one.
2409 if (q
->dma_drain_size
&& blk_rq_bytes(rq
) &&
2410 !(rq
->rq_flags
& RQF_DONTPREP
)) {
2412 * remove the space for the drain we added
2413 * so that we don't add it again
2415 --rq
->nr_phys_segments
;
2420 } else if (ret
== BLKPREP_KILL
|| ret
== BLKPREP_INVALID
) {
2421 int err
= (ret
== BLKPREP_INVALID
) ? -EREMOTEIO
: -EIO
;
2423 rq
->rq_flags
|= RQF_QUIET
;
2425 * Mark this request as started so we don't trigger
2426 * any debug logic in the end I/O path.
2428 blk_start_request(rq
);
2429 __blk_end_request_all(rq
, err
);
2431 printk(KERN_ERR
"%s: bad return=%d\n", __func__
, ret
);
2438 EXPORT_SYMBOL(blk_peek_request
);
2440 void blk_dequeue_request(struct request
*rq
)
2442 struct request_queue
*q
= rq
->q
;
2444 BUG_ON(list_empty(&rq
->queuelist
));
2445 BUG_ON(ELV_ON_HASH(rq
));
2447 list_del_init(&rq
->queuelist
);
2450 * the time frame between a request being removed from the lists
2451 * and to it is freed is accounted as io that is in progress at
2454 if (blk_account_rq(rq
)) {
2455 q
->in_flight
[rq_is_sync(rq
)]++;
2456 set_io_start_time_ns(rq
);
2461 * blk_start_request - start request processing on the driver
2462 * @req: request to dequeue
2465 * Dequeue @req and start timeout timer on it. This hands off the
2466 * request to the driver.
2468 * Block internal functions which don't want to start timer should
2469 * call blk_dequeue_request().
2472 * queue_lock must be held.
2474 void blk_start_request(struct request
*req
)
2476 blk_dequeue_request(req
);
2478 if (test_bit(QUEUE_FLAG_STATS
, &req
->q
->queue_flags
)) {
2479 blk_stat_set_issue_time(&req
->issue_stat
);
2480 req
->rq_flags
|= RQF_STATS
;
2481 wbt_issue(req
->q
->rq_wb
, &req
->issue_stat
);
2485 * We are now handing the request to the hardware, initialize
2486 * resid_len to full count and add the timeout handler.
2488 req
->resid_len
= blk_rq_bytes(req
);
2489 if (unlikely(blk_bidi_rq(req
)))
2490 req
->next_rq
->resid_len
= blk_rq_bytes(req
->next_rq
);
2492 BUG_ON(test_bit(REQ_ATOM_COMPLETE
, &req
->atomic_flags
));
2495 EXPORT_SYMBOL(blk_start_request
);
2498 * blk_fetch_request - fetch a request from a request queue
2499 * @q: request queue to fetch a request from
2502 * Return the request at the top of @q. The request is started on
2503 * return and LLD can start processing it immediately.
2506 * Pointer to the request at the top of @q if available. Null
2510 * queue_lock must be held.
2512 struct request
*blk_fetch_request(struct request_queue
*q
)
2516 rq
= blk_peek_request(q
);
2518 blk_start_request(rq
);
2521 EXPORT_SYMBOL(blk_fetch_request
);
2524 * blk_update_request - Special helper function for request stacking drivers
2525 * @req: the request being processed
2526 * @error: %0 for success, < %0 for error
2527 * @nr_bytes: number of bytes to complete @req
2530 * Ends I/O on a number of bytes attached to @req, but doesn't complete
2531 * the request structure even if @req doesn't have leftover.
2532 * If @req has leftover, sets it up for the next range of segments.
2534 * This special helper function is only for request stacking drivers
2535 * (e.g. request-based dm) so that they can handle partial completion.
2536 * Actual device drivers should use blk_end_request instead.
2538 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
2539 * %false return from this function.
2542 * %false - this request doesn't have any more data
2543 * %true - this request has more data
2545 bool blk_update_request(struct request
*req
, int error
, unsigned int nr_bytes
)
2549 trace_block_rq_complete(req
->q
, req
, nr_bytes
);
2555 * For fs requests, rq is just carrier of independent bio's
2556 * and each partial completion should be handled separately.
2557 * Reset per-request error on each partial completion.
2559 * TODO: tj: This is too subtle. It would be better to let
2560 * low level drivers do what they see fit.
2562 if (req
->cmd_type
== REQ_TYPE_FS
)
2565 if (error
&& req
->cmd_type
== REQ_TYPE_FS
&&
2566 !(req
->rq_flags
& RQF_QUIET
)) {
2571 error_type
= "recoverable transport";
2574 error_type
= "critical target";
2577 error_type
= "critical nexus";
2580 error_type
= "timeout";
2583 error_type
= "critical space allocation";
2586 error_type
= "critical medium";
2593 printk_ratelimited(KERN_ERR
"%s: %s error, dev %s, sector %llu\n",
2594 __func__
, error_type
, req
->rq_disk
?
2595 req
->rq_disk
->disk_name
: "?",
2596 (unsigned long long)blk_rq_pos(req
));
2600 blk_account_io_completion(req
, nr_bytes
);
2604 struct bio
*bio
= req
->bio
;
2605 unsigned bio_bytes
= min(bio
->bi_iter
.bi_size
, nr_bytes
);
2607 if (bio_bytes
== bio
->bi_iter
.bi_size
)
2608 req
->bio
= bio
->bi_next
;
2610 req_bio_endio(req
, bio
, bio_bytes
, error
);
2612 total_bytes
+= bio_bytes
;
2613 nr_bytes
-= bio_bytes
;
2624 * Reset counters so that the request stacking driver
2625 * can find how many bytes remain in the request
2628 req
->__data_len
= 0;
2632 req
->__data_len
-= total_bytes
;
2634 /* update sector only for requests with clear definition of sector */
2635 if (req
->cmd_type
== REQ_TYPE_FS
)
2636 req
->__sector
+= total_bytes
>> 9;
2638 /* mixed attributes always follow the first bio */
2639 if (req
->rq_flags
& RQF_MIXED_MERGE
) {
2640 req
->cmd_flags
&= ~REQ_FAILFAST_MASK
;
2641 req
->cmd_flags
|= req
->bio
->bi_opf
& REQ_FAILFAST_MASK
;
2645 * If total number of sectors is less than the first segment
2646 * size, something has gone terribly wrong.
2648 if (blk_rq_bytes(req
) < blk_rq_cur_bytes(req
)) {
2649 blk_dump_rq_flags(req
, "request botched");
2650 req
->__data_len
= blk_rq_cur_bytes(req
);
2653 /* recalculate the number of segments */
2654 blk_recalc_rq_segments(req
);
2658 EXPORT_SYMBOL_GPL(blk_update_request
);
2660 static bool blk_update_bidi_request(struct request
*rq
, int error
,
2661 unsigned int nr_bytes
,
2662 unsigned int bidi_bytes
)
2664 if (blk_update_request(rq
, error
, nr_bytes
))
2667 /* Bidi request must be completed as a whole */
2668 if (unlikely(blk_bidi_rq(rq
)) &&
2669 blk_update_request(rq
->next_rq
, error
, bidi_bytes
))
2672 if (blk_queue_add_random(rq
->q
))
2673 add_disk_randomness(rq
->rq_disk
);
2679 * blk_unprep_request - unprepare a request
2682 * This function makes a request ready for complete resubmission (or
2683 * completion). It happens only after all error handling is complete,
2684 * so represents the appropriate moment to deallocate any resources
2685 * that were allocated to the request in the prep_rq_fn. The queue
2686 * lock is held when calling this.
2688 void blk_unprep_request(struct request
*req
)
2690 struct request_queue
*q
= req
->q
;
2692 req
->rq_flags
&= ~RQF_DONTPREP
;
2693 if (q
->unprep_rq_fn
)
2694 q
->unprep_rq_fn(q
, req
);
2696 EXPORT_SYMBOL_GPL(blk_unprep_request
);
2699 * queue lock must be held
2701 void blk_finish_request(struct request
*req
, int error
)
2703 struct request_queue
*q
= req
->q
;
2705 if (req
->rq_flags
& RQF_STATS
)
2706 blk_stat_add(&q
->rq_stats
[rq_data_dir(req
)], req
);
2708 if (req
->rq_flags
& RQF_QUEUED
)
2709 blk_queue_end_tag(q
, req
);
2711 BUG_ON(blk_queued_rq(req
));
2713 if (unlikely(laptop_mode
) && req
->cmd_type
== REQ_TYPE_FS
)
2714 laptop_io_completion(&req
->q
->backing_dev_info
);
2716 blk_delete_timer(req
);
2718 if (req
->rq_flags
& RQF_DONTPREP
)
2719 blk_unprep_request(req
);
2721 blk_account_io_done(req
);
2724 wbt_done(req
->q
->rq_wb
, &req
->issue_stat
);
2725 req
->end_io(req
, error
);
2727 if (blk_bidi_rq(req
))
2728 __blk_put_request(req
->next_rq
->q
, req
->next_rq
);
2730 __blk_put_request(q
, req
);
2733 EXPORT_SYMBOL(blk_finish_request
);
2736 * blk_end_bidi_request - Complete a bidi request
2737 * @rq: the request to complete
2738 * @error: %0 for success, < %0 for error
2739 * @nr_bytes: number of bytes to complete @rq
2740 * @bidi_bytes: number of bytes to complete @rq->next_rq
2743 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2744 * Drivers that supports bidi can safely call this member for any
2745 * type of request, bidi or uni. In the later case @bidi_bytes is
2749 * %false - we are done with this request
2750 * %true - still buffers pending for this request
2752 static bool blk_end_bidi_request(struct request
*rq
, int error
,
2753 unsigned int nr_bytes
, unsigned int bidi_bytes
)
2755 struct request_queue
*q
= rq
->q
;
2756 unsigned long flags
;
2758 if (blk_update_bidi_request(rq
, error
, nr_bytes
, bidi_bytes
))
2761 spin_lock_irqsave(q
->queue_lock
, flags
);
2762 blk_finish_request(rq
, error
);
2763 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2769 * __blk_end_bidi_request - Complete a bidi request with queue lock held
2770 * @rq: the request to complete
2771 * @error: %0 for success, < %0 for error
2772 * @nr_bytes: number of bytes to complete @rq
2773 * @bidi_bytes: number of bytes to complete @rq->next_rq
2776 * Identical to blk_end_bidi_request() except that queue lock is
2777 * assumed to be locked on entry and remains so on return.
2780 * %false - we are done with this request
2781 * %true - still buffers pending for this request
2783 bool __blk_end_bidi_request(struct request
*rq
, int error
,
2784 unsigned int nr_bytes
, unsigned int bidi_bytes
)
2786 if (blk_update_bidi_request(rq
, error
, nr_bytes
, bidi_bytes
))
2789 blk_finish_request(rq
, error
);
2795 * blk_end_request - Helper function for drivers to complete the request.
2796 * @rq: the request being processed
2797 * @error: %0 for success, < %0 for error
2798 * @nr_bytes: number of bytes to complete
2801 * Ends I/O on a number of bytes attached to @rq.
2802 * If @rq has leftover, sets it up for the next range of segments.
2805 * %false - we are done with this request
2806 * %true - still buffers pending for this request
2808 bool blk_end_request(struct request
*rq
, int error
, unsigned int nr_bytes
)
2810 return blk_end_bidi_request(rq
, error
, nr_bytes
, 0);
2812 EXPORT_SYMBOL(blk_end_request
);
2815 * blk_end_request_all - Helper function for drives to finish the request.
2816 * @rq: the request to finish
2817 * @error: %0 for success, < %0 for error
2820 * Completely finish @rq.
2822 void blk_end_request_all(struct request
*rq
, int error
)
2825 unsigned int bidi_bytes
= 0;
2827 if (unlikely(blk_bidi_rq(rq
)))
2828 bidi_bytes
= blk_rq_bytes(rq
->next_rq
);
2830 pending
= blk_end_bidi_request(rq
, error
, blk_rq_bytes(rq
), bidi_bytes
);
2833 EXPORT_SYMBOL(blk_end_request_all
);
2836 * blk_end_request_cur - Helper function to finish the current request chunk.
2837 * @rq: the request to finish the current chunk for
2838 * @error: %0 for success, < %0 for error
2841 * Complete the current consecutively mapped chunk from @rq.
2844 * %false - we are done with this request
2845 * %true - still buffers pending for this request
2847 bool blk_end_request_cur(struct request
*rq
, int error
)
2849 return blk_end_request(rq
, error
, blk_rq_cur_bytes(rq
));
2851 EXPORT_SYMBOL(blk_end_request_cur
);
2854 * blk_end_request_err - Finish a request till the next failure boundary.
2855 * @rq: the request to finish till the next failure boundary for
2856 * @error: must be negative errno
2859 * Complete @rq till the next failure boundary.
2862 * %false - we are done with this request
2863 * %true - still buffers pending for this request
2865 bool blk_end_request_err(struct request
*rq
, int error
)
2867 WARN_ON(error
>= 0);
2868 return blk_end_request(rq
, error
, blk_rq_err_bytes(rq
));
2870 EXPORT_SYMBOL_GPL(blk_end_request_err
);
2873 * __blk_end_request - Helper function for drivers to complete the request.
2874 * @rq: the request being processed
2875 * @error: %0 for success, < %0 for error
2876 * @nr_bytes: number of bytes to complete
2879 * Must be called with queue lock held unlike blk_end_request().
2882 * %false - we are done with this request
2883 * %true - still buffers pending for this request
2885 bool __blk_end_request(struct request
*rq
, int error
, unsigned int nr_bytes
)
2887 return __blk_end_bidi_request(rq
, error
, nr_bytes
, 0);
2889 EXPORT_SYMBOL(__blk_end_request
);
2892 * __blk_end_request_all - Helper function for drives to finish the request.
2893 * @rq: the request to finish
2894 * @error: %0 for success, < %0 for error
2897 * Completely finish @rq. Must be called with queue lock held.
2899 void __blk_end_request_all(struct request
*rq
, int error
)
2902 unsigned int bidi_bytes
= 0;
2904 if (unlikely(blk_bidi_rq(rq
)))
2905 bidi_bytes
= blk_rq_bytes(rq
->next_rq
);
2907 pending
= __blk_end_bidi_request(rq
, error
, blk_rq_bytes(rq
), bidi_bytes
);
2910 EXPORT_SYMBOL(__blk_end_request_all
);
2913 * __blk_end_request_cur - Helper function to finish the current request chunk.
2914 * @rq: the request to finish the current chunk for
2915 * @error: %0 for success, < %0 for error
2918 * Complete the current consecutively mapped chunk from @rq. Must
2919 * be called with queue lock held.
2922 * %false - we are done with this request
2923 * %true - still buffers pending for this request
2925 bool __blk_end_request_cur(struct request
*rq
, int error
)
2927 return __blk_end_request(rq
, error
, blk_rq_cur_bytes(rq
));
2929 EXPORT_SYMBOL(__blk_end_request_cur
);
2932 * __blk_end_request_err - Finish a request till the next failure boundary.
2933 * @rq: the request to finish till the next failure boundary for
2934 * @error: must be negative errno
2937 * Complete @rq till the next failure boundary. Must be called
2938 * with queue lock held.
2941 * %false - we are done with this request
2942 * %true - still buffers pending for this request
2944 bool __blk_end_request_err(struct request
*rq
, int error
)
2946 WARN_ON(error
>= 0);
2947 return __blk_end_request(rq
, error
, blk_rq_err_bytes(rq
));
2949 EXPORT_SYMBOL_GPL(__blk_end_request_err
);
2951 void blk_rq_bio_prep(struct request_queue
*q
, struct request
*rq
,
2954 if (bio_has_data(bio
))
2955 rq
->nr_phys_segments
= bio_phys_segments(q
, bio
);
2957 rq
->__data_len
= bio
->bi_iter
.bi_size
;
2958 rq
->bio
= rq
->biotail
= bio
;
2961 rq
->rq_disk
= bio
->bi_bdev
->bd_disk
;
2964 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
2966 * rq_flush_dcache_pages - Helper function to flush all pages in a request
2967 * @rq: the request to be flushed
2970 * Flush all pages in @rq.
2972 void rq_flush_dcache_pages(struct request
*rq
)
2974 struct req_iterator iter
;
2975 struct bio_vec bvec
;
2977 rq_for_each_segment(bvec
, rq
, iter
)
2978 flush_dcache_page(bvec
.bv_page
);
2980 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages
);
2984 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
2985 * @q : the queue of the device being checked
2988 * Check if underlying low-level drivers of a device are busy.
2989 * If the drivers want to export their busy state, they must set own
2990 * exporting function using blk_queue_lld_busy() first.
2992 * Basically, this function is used only by request stacking drivers
2993 * to stop dispatching requests to underlying devices when underlying
2994 * devices are busy. This behavior helps more I/O merging on the queue
2995 * of the request stacking driver and prevents I/O throughput regression
2996 * on burst I/O load.
2999 * 0 - Not busy (The request stacking driver should dispatch request)
3000 * 1 - Busy (The request stacking driver should stop dispatching request)
3002 int blk_lld_busy(struct request_queue
*q
)
3005 return q
->lld_busy_fn(q
);
3009 EXPORT_SYMBOL_GPL(blk_lld_busy
);
3012 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
3013 * @rq: the clone request to be cleaned up
3016 * Free all bios in @rq for a cloned request.
3018 void blk_rq_unprep_clone(struct request
*rq
)
3022 while ((bio
= rq
->bio
) != NULL
) {
3023 rq
->bio
= bio
->bi_next
;
3028 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone
);
3031 * Copy attributes of the original request to the clone request.
3032 * The actual data parts (e.g. ->cmd, ->sense) are not copied.
3034 static void __blk_rq_prep_clone(struct request
*dst
, struct request
*src
)
3036 dst
->cpu
= src
->cpu
;
3037 dst
->cmd_flags
= src
->cmd_flags
| REQ_NOMERGE
;
3038 dst
->cmd_type
= src
->cmd_type
;
3039 dst
->__sector
= blk_rq_pos(src
);
3040 dst
->__data_len
= blk_rq_bytes(src
);
3041 dst
->nr_phys_segments
= src
->nr_phys_segments
;
3042 dst
->ioprio
= src
->ioprio
;
3043 dst
->extra_len
= src
->extra_len
;
3047 * blk_rq_prep_clone - Helper function to setup clone request
3048 * @rq: the request to be setup
3049 * @rq_src: original request to be cloned
3050 * @bs: bio_set that bios for clone are allocated from
3051 * @gfp_mask: memory allocation mask for bio
3052 * @bio_ctr: setup function to be called for each clone bio.
3053 * Returns %0 for success, non %0 for failure.
3054 * @data: private data to be passed to @bio_ctr
3057 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
3058 * The actual data parts of @rq_src (e.g. ->cmd, ->sense)
3059 * are not copied, and copying such parts is the caller's responsibility.
3060 * Also, pages which the original bios are pointing to are not copied
3061 * and the cloned bios just point same pages.
3062 * So cloned bios must be completed before original bios, which means
3063 * the caller must complete @rq before @rq_src.
3065 int blk_rq_prep_clone(struct request
*rq
, struct request
*rq_src
,
3066 struct bio_set
*bs
, gfp_t gfp_mask
,
3067 int (*bio_ctr
)(struct bio
*, struct bio
*, void *),
3070 struct bio
*bio
, *bio_src
;
3075 __rq_for_each_bio(bio_src
, rq_src
) {
3076 bio
= bio_clone_fast(bio_src
, gfp_mask
, bs
);
3080 if (bio_ctr
&& bio_ctr(bio
, bio_src
, data
))
3084 rq
->biotail
->bi_next
= bio
;
3087 rq
->bio
= rq
->biotail
= bio
;
3090 __blk_rq_prep_clone(rq
, rq_src
);
3097 blk_rq_unprep_clone(rq
);
3101 EXPORT_SYMBOL_GPL(blk_rq_prep_clone
);
3103 int kblockd_schedule_work(struct work_struct
*work
)
3105 return queue_work(kblockd_workqueue
, work
);
3107 EXPORT_SYMBOL(kblockd_schedule_work
);
3109 int kblockd_schedule_work_on(int cpu
, struct work_struct
*work
)
3111 return queue_work_on(cpu
, kblockd_workqueue
, work
);
3113 EXPORT_SYMBOL(kblockd_schedule_work_on
);
3115 int kblockd_schedule_delayed_work(struct delayed_work
*dwork
,
3116 unsigned long delay
)
3118 return queue_delayed_work(kblockd_workqueue
, dwork
, delay
);
3120 EXPORT_SYMBOL(kblockd_schedule_delayed_work
);
3122 int kblockd_schedule_delayed_work_on(int cpu
, struct delayed_work
*dwork
,
3123 unsigned long delay
)
3125 return queue_delayed_work_on(cpu
, kblockd_workqueue
, dwork
, delay
);
3127 EXPORT_SYMBOL(kblockd_schedule_delayed_work_on
);
3130 * blk_start_plug - initialize blk_plug and track it inside the task_struct
3131 * @plug: The &struct blk_plug that needs to be initialized
3134 * Tracking blk_plug inside the task_struct will help with auto-flushing the
3135 * pending I/O should the task end up blocking between blk_start_plug() and
3136 * blk_finish_plug(). This is important from a performance perspective, but
3137 * also ensures that we don't deadlock. For instance, if the task is blocking
3138 * for a memory allocation, memory reclaim could end up wanting to free a
3139 * page belonging to that request that is currently residing in our private
3140 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
3141 * this kind of deadlock.
3143 void blk_start_plug(struct blk_plug
*plug
)
3145 struct task_struct
*tsk
= current
;
3148 * If this is a nested plug, don't actually assign it.
3153 INIT_LIST_HEAD(&plug
->list
);
3154 INIT_LIST_HEAD(&plug
->mq_list
);
3155 INIT_LIST_HEAD(&plug
->cb_list
);
3157 * Store ordering should not be needed here, since a potential
3158 * preempt will imply a full memory barrier
3162 EXPORT_SYMBOL(blk_start_plug
);
3164 static int plug_rq_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
3166 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
3167 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
3169 return !(rqa
->q
< rqb
->q
||
3170 (rqa
->q
== rqb
->q
&& blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
3174 * If 'from_schedule' is true, then postpone the dispatch of requests
3175 * until a safe kblockd context. We due this to avoid accidental big
3176 * additional stack usage in driver dispatch, in places where the originally
3177 * plugger did not intend it.
3179 static void queue_unplugged(struct request_queue
*q
, unsigned int depth
,
3181 __releases(q
->queue_lock
)
3183 trace_block_unplug(q
, depth
, !from_schedule
);
3186 blk_run_queue_async(q
);
3189 spin_unlock(q
->queue_lock
);
3192 static void flush_plug_callbacks(struct blk_plug
*plug
, bool from_schedule
)
3194 LIST_HEAD(callbacks
);
3196 while (!list_empty(&plug
->cb_list
)) {
3197 list_splice_init(&plug
->cb_list
, &callbacks
);
3199 while (!list_empty(&callbacks
)) {
3200 struct blk_plug_cb
*cb
= list_first_entry(&callbacks
,
3203 list_del(&cb
->list
);
3204 cb
->callback(cb
, from_schedule
);
3209 struct blk_plug_cb
*blk_check_plugged(blk_plug_cb_fn unplug
, void *data
,
3212 struct blk_plug
*plug
= current
->plug
;
3213 struct blk_plug_cb
*cb
;
3218 list_for_each_entry(cb
, &plug
->cb_list
, list
)
3219 if (cb
->callback
== unplug
&& cb
->data
== data
)
3222 /* Not currently on the callback list */
3223 BUG_ON(size
< sizeof(*cb
));
3224 cb
= kzalloc(size
, GFP_ATOMIC
);
3227 cb
->callback
= unplug
;
3228 list_add(&cb
->list
, &plug
->cb_list
);
3232 EXPORT_SYMBOL(blk_check_plugged
);
3234 void blk_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
3236 struct request_queue
*q
;
3237 unsigned long flags
;
3242 flush_plug_callbacks(plug
, from_schedule
);
3244 if (!list_empty(&plug
->mq_list
))
3245 blk_mq_flush_plug_list(plug
, from_schedule
);
3247 if (list_empty(&plug
->list
))
3250 list_splice_init(&plug
->list
, &list
);
3252 list_sort(NULL
, &list
, plug_rq_cmp
);
3258 * Save and disable interrupts here, to avoid doing it for every
3259 * queue lock we have to take.
3261 local_irq_save(flags
);
3262 while (!list_empty(&list
)) {
3263 rq
= list_entry_rq(list
.next
);
3264 list_del_init(&rq
->queuelist
);
3268 * This drops the queue lock
3271 queue_unplugged(q
, depth
, from_schedule
);
3274 spin_lock(q
->queue_lock
);
3278 * Short-circuit if @q is dead
3280 if (unlikely(blk_queue_dying(q
))) {
3281 __blk_end_request_all(rq
, -ENODEV
);
3286 * rq is already accounted, so use raw insert
3288 if (rq
->cmd_flags
& (REQ_PREFLUSH
| REQ_FUA
))
3289 __elv_add_request(q
, rq
, ELEVATOR_INSERT_FLUSH
);
3291 __elv_add_request(q
, rq
, ELEVATOR_INSERT_SORT_MERGE
);
3297 * This drops the queue lock
3300 queue_unplugged(q
, depth
, from_schedule
);
3302 local_irq_restore(flags
);
3305 void blk_finish_plug(struct blk_plug
*plug
)
3307 if (plug
!= current
->plug
)
3309 blk_flush_plug_list(plug
, false);
3311 current
->plug
= NULL
;
3313 EXPORT_SYMBOL(blk_finish_plug
);
3317 * blk_pm_runtime_init - Block layer runtime PM initialization routine
3318 * @q: the queue of the device
3319 * @dev: the device the queue belongs to
3322 * Initialize runtime-PM-related fields for @q and start auto suspend for
3323 * @dev. Drivers that want to take advantage of request-based runtime PM
3324 * should call this function after @dev has been initialized, and its
3325 * request queue @q has been allocated, and runtime PM for it can not happen
3326 * yet(either due to disabled/forbidden or its usage_count > 0). In most
3327 * cases, driver should call this function before any I/O has taken place.
3329 * This function takes care of setting up using auto suspend for the device,
3330 * the autosuspend delay is set to -1 to make runtime suspend impossible
3331 * until an updated value is either set by user or by driver. Drivers do
3332 * not need to touch other autosuspend settings.
3334 * The block layer runtime PM is request based, so only works for drivers
3335 * that use request as their IO unit instead of those directly use bio's.
3337 void blk_pm_runtime_init(struct request_queue
*q
, struct device
*dev
)
3340 q
->rpm_status
= RPM_ACTIVE
;
3341 pm_runtime_set_autosuspend_delay(q
->dev
, -1);
3342 pm_runtime_use_autosuspend(q
->dev
);
3344 EXPORT_SYMBOL(blk_pm_runtime_init
);
3347 * blk_pre_runtime_suspend - Pre runtime suspend check
3348 * @q: the queue of the device
3351 * This function will check if runtime suspend is allowed for the device
3352 * by examining if there are any requests pending in the queue. If there
3353 * are requests pending, the device can not be runtime suspended; otherwise,
3354 * the queue's status will be updated to SUSPENDING and the driver can
3355 * proceed to suspend the device.
3357 * For the not allowed case, we mark last busy for the device so that
3358 * runtime PM core will try to autosuspend it some time later.
3360 * This function should be called near the start of the device's
3361 * runtime_suspend callback.
3364 * 0 - OK to runtime suspend the device
3365 * -EBUSY - Device should not be runtime suspended
3367 int blk_pre_runtime_suspend(struct request_queue
*q
)
3374 spin_lock_irq(q
->queue_lock
);
3375 if (q
->nr_pending
) {
3377 pm_runtime_mark_last_busy(q
->dev
);
3379 q
->rpm_status
= RPM_SUSPENDING
;
3381 spin_unlock_irq(q
->queue_lock
);
3384 EXPORT_SYMBOL(blk_pre_runtime_suspend
);
3387 * blk_post_runtime_suspend - Post runtime suspend processing
3388 * @q: the queue of the device
3389 * @err: return value of the device's runtime_suspend function
3392 * Update the queue's runtime status according to the return value of the
3393 * device's runtime suspend function and mark last busy for the device so
3394 * that PM core will try to auto suspend the device at a later time.
3396 * This function should be called near the end of the device's
3397 * runtime_suspend callback.
3399 void blk_post_runtime_suspend(struct request_queue
*q
, int err
)
3404 spin_lock_irq(q
->queue_lock
);
3406 q
->rpm_status
= RPM_SUSPENDED
;
3408 q
->rpm_status
= RPM_ACTIVE
;
3409 pm_runtime_mark_last_busy(q
->dev
);
3411 spin_unlock_irq(q
->queue_lock
);
3413 EXPORT_SYMBOL(blk_post_runtime_suspend
);
3416 * blk_pre_runtime_resume - Pre runtime resume processing
3417 * @q: the queue of the device
3420 * Update the queue's runtime status to RESUMING in preparation for the
3421 * runtime resume of the device.
3423 * This function should be called near the start of the device's
3424 * runtime_resume callback.
3426 void blk_pre_runtime_resume(struct request_queue
*q
)
3431 spin_lock_irq(q
->queue_lock
);
3432 q
->rpm_status
= RPM_RESUMING
;
3433 spin_unlock_irq(q
->queue_lock
);
3435 EXPORT_SYMBOL(blk_pre_runtime_resume
);
3438 * blk_post_runtime_resume - Post runtime resume processing
3439 * @q: the queue of the device
3440 * @err: return value of the device's runtime_resume function
3443 * Update the queue's runtime status according to the return value of the
3444 * device's runtime_resume function. If it is successfully resumed, process
3445 * the requests that are queued into the device's queue when it is resuming
3446 * and then mark last busy and initiate autosuspend for it.
3448 * This function should be called near the end of the device's
3449 * runtime_resume callback.
3451 void blk_post_runtime_resume(struct request_queue
*q
, int err
)
3456 spin_lock_irq(q
->queue_lock
);
3458 q
->rpm_status
= RPM_ACTIVE
;
3460 pm_runtime_mark_last_busy(q
->dev
);
3461 pm_request_autosuspend(q
->dev
);
3463 q
->rpm_status
= RPM_SUSPENDED
;
3465 spin_unlock_irq(q
->queue_lock
);
3467 EXPORT_SYMBOL(blk_post_runtime_resume
);
3470 * blk_set_runtime_active - Force runtime status of the queue to be active
3471 * @q: the queue of the device
3473 * If the device is left runtime suspended during system suspend the resume
3474 * hook typically resumes the device and corrects runtime status
3475 * accordingly. However, that does not affect the queue runtime PM status
3476 * which is still "suspended". This prevents processing requests from the
3479 * This function can be used in driver's resume hook to correct queue
3480 * runtime PM status and re-enable peeking requests from the queue. It
3481 * should be called before first request is added to the queue.
3483 void blk_set_runtime_active(struct request_queue
*q
)
3485 spin_lock_irq(q
->queue_lock
);
3486 q
->rpm_status
= RPM_ACTIVE
;
3487 pm_runtime_mark_last_busy(q
->dev
);
3488 pm_request_autosuspend(q
->dev
);
3489 spin_unlock_irq(q
->queue_lock
);
3491 EXPORT_SYMBOL(blk_set_runtime_active
);
3494 int __init
blk_dev_init(void)
3496 BUILD_BUG_ON(REQ_OP_LAST
>= (1 << REQ_OP_BITS
));
3497 BUILD_BUG_ON(REQ_OP_BITS
+ REQ_FLAG_BITS
> 8 *
3498 FIELD_SIZEOF(struct request
, cmd_flags
));
3499 BUILD_BUG_ON(REQ_OP_BITS
+ REQ_FLAG_BITS
> 8 *
3500 FIELD_SIZEOF(struct bio
, bi_opf
));
3502 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
3503 kblockd_workqueue
= alloc_workqueue("kblockd",
3504 WQ_MEM_RECLAIM
| WQ_HIGHPRI
, 0);
3505 if (!kblockd_workqueue
)
3506 panic("Failed to create kblockd\n");
3508 request_cachep
= kmem_cache_create("blkdev_requests",
3509 sizeof(struct request
), 0, SLAB_PANIC
, NULL
);
3511 blk_requestq_cachep
= kmem_cache_create("request_queue",
3512 sizeof(struct request_queue
), 0, SLAB_PANIC
, NULL
);