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>
43 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap
);
44 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap
);
45 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete
);
46 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split
);
47 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug
);
49 DEFINE_IDA(blk_queue_ida
);
52 * For the allocated request tables
54 struct kmem_cache
*request_cachep
;
57 * For queue allocation
59 struct kmem_cache
*blk_requestq_cachep
;
62 * Controlling structure to kblockd
64 static struct workqueue_struct
*kblockd_workqueue
;
66 static void blk_clear_congested(struct request_list
*rl
, int sync
)
68 #ifdef CONFIG_CGROUP_WRITEBACK
69 clear_wb_congested(rl
->blkg
->wb_congested
, sync
);
72 * If !CGROUP_WRITEBACK, all blkg's map to bdi->wb and we shouldn't
73 * flip its congestion state for events on other blkcgs.
75 if (rl
== &rl
->q
->root_rl
)
76 clear_wb_congested(rl
->q
->backing_dev_info
.wb
.congested
, sync
);
80 static void blk_set_congested(struct request_list
*rl
, int sync
)
82 #ifdef CONFIG_CGROUP_WRITEBACK
83 set_wb_congested(rl
->blkg
->wb_congested
, sync
);
85 /* see blk_clear_congested() */
86 if (rl
== &rl
->q
->root_rl
)
87 set_wb_congested(rl
->q
->backing_dev_info
.wb
.congested
, sync
);
91 void blk_queue_congestion_threshold(struct request_queue
*q
)
95 nr
= q
->nr_requests
- (q
->nr_requests
/ 8) + 1;
96 if (nr
> q
->nr_requests
)
98 q
->nr_congestion_on
= nr
;
100 nr
= q
->nr_requests
- (q
->nr_requests
/ 8) - (q
->nr_requests
/ 16) - 1;
103 q
->nr_congestion_off
= nr
;
107 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
110 * Locates the passed device's request queue and returns the address of its
111 * backing_dev_info. This function can only be called if @bdev is opened
112 * and the return value is never NULL.
114 struct backing_dev_info
*blk_get_backing_dev_info(struct block_device
*bdev
)
116 struct request_queue
*q
= bdev_get_queue(bdev
);
118 return &q
->backing_dev_info
;
120 EXPORT_SYMBOL(blk_get_backing_dev_info
);
122 void blk_rq_init(struct request_queue
*q
, struct request
*rq
)
124 memset(rq
, 0, sizeof(*rq
));
126 INIT_LIST_HEAD(&rq
->queuelist
);
127 INIT_LIST_HEAD(&rq
->timeout_list
);
130 rq
->__sector
= (sector_t
) -1;
131 INIT_HLIST_NODE(&rq
->hash
);
132 RB_CLEAR_NODE(&rq
->rb_node
);
134 rq
->cmd_len
= BLK_MAX_CDB
;
136 rq
->start_time
= jiffies
;
137 set_start_time_ns(rq
);
140 EXPORT_SYMBOL(blk_rq_init
);
142 static void req_bio_endio(struct request
*rq
, struct bio
*bio
,
143 unsigned int nbytes
, int error
)
146 bio
->bi_error
= error
;
148 if (unlikely(rq
->cmd_flags
& REQ_QUIET
))
149 bio_set_flag(bio
, BIO_QUIET
);
151 bio_advance(bio
, nbytes
);
153 /* don't actually finish bio if it's part of flush sequence */
154 if (bio
->bi_iter
.bi_size
== 0 && !(rq
->cmd_flags
& REQ_FLUSH_SEQ
))
158 void blk_dump_rq_flags(struct request
*rq
, char *msg
)
162 printk(KERN_INFO
"%s: dev %s: type=%x, flags=%llx\n", msg
,
163 rq
->rq_disk
? rq
->rq_disk
->disk_name
: "?", rq
->cmd_type
,
164 (unsigned long long) rq
->cmd_flags
);
166 printk(KERN_INFO
" sector %llu, nr/cnr %u/%u\n",
167 (unsigned long long)blk_rq_pos(rq
),
168 blk_rq_sectors(rq
), blk_rq_cur_sectors(rq
));
169 printk(KERN_INFO
" bio %p, biotail %p, len %u\n",
170 rq
->bio
, rq
->biotail
, blk_rq_bytes(rq
));
172 if (rq
->cmd_type
== REQ_TYPE_BLOCK_PC
) {
173 printk(KERN_INFO
" cdb: ");
174 for (bit
= 0; bit
< BLK_MAX_CDB
; bit
++)
175 printk("%02x ", rq
->cmd
[bit
]);
179 EXPORT_SYMBOL(blk_dump_rq_flags
);
181 static void blk_delay_work(struct work_struct
*work
)
183 struct request_queue
*q
;
185 q
= container_of(work
, struct request_queue
, delay_work
.work
);
186 spin_lock_irq(q
->queue_lock
);
188 spin_unlock_irq(q
->queue_lock
);
192 * blk_delay_queue - restart queueing after defined interval
193 * @q: The &struct request_queue in question
194 * @msecs: Delay in msecs
197 * Sometimes queueing needs to be postponed for a little while, to allow
198 * resources to come back. This function will make sure that queueing is
199 * restarted around the specified time. Queue lock must be held.
201 void blk_delay_queue(struct request_queue
*q
, unsigned long msecs
)
203 if (likely(!blk_queue_dead(q
)))
204 queue_delayed_work(kblockd_workqueue
, &q
->delay_work
,
205 msecs_to_jiffies(msecs
));
207 EXPORT_SYMBOL(blk_delay_queue
);
210 * blk_start_queue_async - asynchronously restart a previously stopped queue
211 * @q: The &struct request_queue in question
214 * blk_start_queue_async() will clear the stop flag on the queue, and
215 * ensure that the request_fn for the queue is run from an async
218 void blk_start_queue_async(struct request_queue
*q
)
220 queue_flag_clear(QUEUE_FLAG_STOPPED
, q
);
221 blk_run_queue_async(q
);
223 EXPORT_SYMBOL(blk_start_queue_async
);
226 * blk_start_queue - restart a previously stopped queue
227 * @q: The &struct request_queue in question
230 * blk_start_queue() will clear the stop flag on the queue, and call
231 * the request_fn for the queue if it was in a stopped state when
232 * entered. Also see blk_stop_queue(). Queue lock must be held.
234 void blk_start_queue(struct request_queue
*q
)
236 WARN_ON(!irqs_disabled());
238 queue_flag_clear(QUEUE_FLAG_STOPPED
, q
);
241 EXPORT_SYMBOL(blk_start_queue
);
244 * blk_stop_queue - stop a queue
245 * @q: The &struct request_queue in question
248 * The Linux block layer assumes that a block driver will consume all
249 * entries on the request queue when the request_fn strategy is called.
250 * Often this will not happen, because of hardware limitations (queue
251 * depth settings). If a device driver gets a 'queue full' response,
252 * or if it simply chooses not to queue more I/O at one point, it can
253 * call this function to prevent the request_fn from being called until
254 * the driver has signalled it's ready to go again. This happens by calling
255 * blk_start_queue() to restart queue operations. Queue lock must be held.
257 void blk_stop_queue(struct request_queue
*q
)
259 cancel_delayed_work(&q
->delay_work
);
260 queue_flag_set(QUEUE_FLAG_STOPPED
, q
);
262 EXPORT_SYMBOL(blk_stop_queue
);
265 * blk_sync_queue - cancel any pending callbacks on a queue
269 * The block layer may perform asynchronous callback activity
270 * on a queue, such as calling the unplug function after a timeout.
271 * A block device may call blk_sync_queue to ensure that any
272 * such activity is cancelled, thus allowing it to release resources
273 * that the callbacks might use. The caller must already have made sure
274 * that its ->make_request_fn will not re-add plugging prior to calling
277 * This function does not cancel any asynchronous activity arising
278 * out of elevator or throttling code. That would require elevator_exit()
279 * and blkcg_exit_queue() to be called with queue lock initialized.
282 void blk_sync_queue(struct request_queue
*q
)
284 del_timer_sync(&q
->timeout
);
287 struct blk_mq_hw_ctx
*hctx
;
290 queue_for_each_hw_ctx(q
, hctx
, i
) {
291 cancel_delayed_work_sync(&hctx
->run_work
);
292 cancel_delayed_work_sync(&hctx
->delay_work
);
295 cancel_delayed_work_sync(&q
->delay_work
);
298 EXPORT_SYMBOL(blk_sync_queue
);
301 * __blk_run_queue_uncond - run a queue whether or not it has been stopped
302 * @q: The queue to run
305 * Invoke request handling on a queue if there are any pending requests.
306 * May be used to restart request handling after a request has completed.
307 * This variant runs the queue whether or not the queue has been
308 * stopped. Must be called with the queue lock held and interrupts
309 * disabled. See also @blk_run_queue.
311 inline void __blk_run_queue_uncond(struct request_queue
*q
)
313 if (unlikely(blk_queue_dead(q
)))
317 * Some request_fn implementations, e.g. scsi_request_fn(), unlock
318 * the queue lock internally. As a result multiple threads may be
319 * running such a request function concurrently. Keep track of the
320 * number of active request_fn invocations such that blk_drain_queue()
321 * can wait until all these request_fn calls have finished.
323 q
->request_fn_active
++;
325 q
->request_fn_active
--;
327 EXPORT_SYMBOL_GPL(__blk_run_queue_uncond
);
330 * __blk_run_queue - run a single device queue
331 * @q: The queue to run
334 * See @blk_run_queue. This variant must be called with the queue lock
335 * held and interrupts disabled.
337 void __blk_run_queue(struct request_queue
*q
)
339 if (unlikely(blk_queue_stopped(q
)))
342 __blk_run_queue_uncond(q
);
344 EXPORT_SYMBOL(__blk_run_queue
);
347 * blk_run_queue_async - run a single device queue in workqueue context
348 * @q: The queue to run
351 * Tells kblockd to perform the equivalent of @blk_run_queue on behalf
352 * of us. The caller must hold the queue lock.
354 void blk_run_queue_async(struct request_queue
*q
)
356 if (likely(!blk_queue_stopped(q
) && !blk_queue_dead(q
)))
357 mod_delayed_work(kblockd_workqueue
, &q
->delay_work
, 0);
359 EXPORT_SYMBOL(blk_run_queue_async
);
362 * blk_run_queue - run a single device queue
363 * @q: The queue to run
366 * Invoke request handling on this queue, if it has pending work to do.
367 * May be used to restart queueing when a request has completed.
369 void blk_run_queue(struct request_queue
*q
)
373 spin_lock_irqsave(q
->queue_lock
, flags
);
375 spin_unlock_irqrestore(q
->queue_lock
, flags
);
377 EXPORT_SYMBOL(blk_run_queue
);
379 void blk_put_queue(struct request_queue
*q
)
381 kobject_put(&q
->kobj
);
383 EXPORT_SYMBOL(blk_put_queue
);
386 * __blk_drain_queue - drain requests from request_queue
388 * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
390 * Drain requests from @q. If @drain_all is set, all requests are drained.
391 * If not, only ELVPRIV requests are drained. The caller is responsible
392 * for ensuring that no new requests which need to be drained are queued.
394 static void __blk_drain_queue(struct request_queue
*q
, bool drain_all
)
395 __releases(q
->queue_lock
)
396 __acquires(q
->queue_lock
)
400 lockdep_assert_held(q
->queue_lock
);
406 * The caller might be trying to drain @q before its
407 * elevator is initialized.
410 elv_drain_elevator(q
);
412 blkcg_drain_queue(q
);
415 * This function might be called on a queue which failed
416 * driver init after queue creation or is not yet fully
417 * active yet. Some drivers (e.g. fd and loop) get unhappy
418 * in such cases. Kick queue iff dispatch queue has
419 * something on it and @q has request_fn set.
421 if (!list_empty(&q
->queue_head
) && q
->request_fn
)
424 drain
|= q
->nr_rqs_elvpriv
;
425 drain
|= q
->request_fn_active
;
428 * Unfortunately, requests are queued at and tracked from
429 * multiple places and there's no single counter which can
430 * be drained. Check all the queues and counters.
433 struct blk_flush_queue
*fq
= blk_get_flush_queue(q
, NULL
);
434 drain
|= !list_empty(&q
->queue_head
);
435 for (i
= 0; i
< 2; i
++) {
436 drain
|= q
->nr_rqs
[i
];
437 drain
|= q
->in_flight
[i
];
439 drain
|= !list_empty(&fq
->flush_queue
[i
]);
446 spin_unlock_irq(q
->queue_lock
);
450 spin_lock_irq(q
->queue_lock
);
454 * With queue marked dead, any woken up waiter will fail the
455 * allocation path, so the wakeup chaining is lost and we're
456 * left with hung waiters. We need to wake up those waiters.
459 struct request_list
*rl
;
461 blk_queue_for_each_rl(rl
, q
)
462 for (i
= 0; i
< ARRAY_SIZE(rl
->wait
); i
++)
463 wake_up_all(&rl
->wait
[i
]);
468 * blk_queue_bypass_start - enter queue bypass mode
469 * @q: queue of interest
471 * In bypass mode, only the dispatch FIFO queue of @q is used. This
472 * function makes @q enter bypass mode and drains all requests which were
473 * throttled or issued before. On return, it's guaranteed that no request
474 * is being throttled or has ELVPRIV set and blk_queue_bypass() %true
475 * inside queue or RCU read lock.
477 void blk_queue_bypass_start(struct request_queue
*q
)
479 spin_lock_irq(q
->queue_lock
);
481 queue_flag_set(QUEUE_FLAG_BYPASS
, q
);
482 spin_unlock_irq(q
->queue_lock
);
485 * Queues start drained. Skip actual draining till init is
486 * complete. This avoids lenghty delays during queue init which
487 * can happen many times during boot.
489 if (blk_queue_init_done(q
)) {
490 spin_lock_irq(q
->queue_lock
);
491 __blk_drain_queue(q
, false);
492 spin_unlock_irq(q
->queue_lock
);
494 /* ensure blk_queue_bypass() is %true inside RCU read lock */
498 EXPORT_SYMBOL_GPL(blk_queue_bypass_start
);
501 * blk_queue_bypass_end - leave queue bypass mode
502 * @q: queue of interest
504 * Leave bypass mode and restore the normal queueing behavior.
506 void blk_queue_bypass_end(struct request_queue
*q
)
508 spin_lock_irq(q
->queue_lock
);
509 if (!--q
->bypass_depth
)
510 queue_flag_clear(QUEUE_FLAG_BYPASS
, q
);
511 WARN_ON_ONCE(q
->bypass_depth
< 0);
512 spin_unlock_irq(q
->queue_lock
);
514 EXPORT_SYMBOL_GPL(blk_queue_bypass_end
);
516 void blk_set_queue_dying(struct request_queue
*q
)
518 queue_flag_set_unlocked(QUEUE_FLAG_DYING
, q
);
521 blk_mq_wake_waiters(q
);
523 struct request_list
*rl
;
525 blk_queue_for_each_rl(rl
, q
) {
527 wake_up(&rl
->wait
[BLK_RW_SYNC
]);
528 wake_up(&rl
->wait
[BLK_RW_ASYNC
]);
533 EXPORT_SYMBOL_GPL(blk_set_queue_dying
);
536 * blk_cleanup_queue - shutdown a request queue
537 * @q: request queue to shutdown
539 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
540 * put it. All future requests will be failed immediately with -ENODEV.
542 void blk_cleanup_queue(struct request_queue
*q
)
544 spinlock_t
*lock
= q
->queue_lock
;
546 /* mark @q DYING, no new request or merges will be allowed afterwards */
547 mutex_lock(&q
->sysfs_lock
);
548 blk_set_queue_dying(q
);
552 * A dying queue is permanently in bypass mode till released. Note
553 * that, unlike blk_queue_bypass_start(), we aren't performing
554 * synchronize_rcu() after entering bypass mode to avoid the delay
555 * as some drivers create and destroy a lot of queues while
556 * probing. This is still safe because blk_release_queue() will be
557 * called only after the queue refcnt drops to zero and nothing,
558 * RCU or not, would be traversing the queue by then.
561 queue_flag_set(QUEUE_FLAG_BYPASS
, q
);
563 queue_flag_set(QUEUE_FLAG_NOMERGES
, q
);
564 queue_flag_set(QUEUE_FLAG_NOXMERGES
, q
);
565 queue_flag_set(QUEUE_FLAG_DYING
, q
);
566 spin_unlock_irq(lock
);
567 mutex_unlock(&q
->sysfs_lock
);
570 * Drain all requests queued before DYING marking. Set DEAD flag to
571 * prevent that q->request_fn() gets invoked after draining finished.
576 __blk_drain_queue(q
, true);
577 queue_flag_set(QUEUE_FLAG_DEAD
, q
);
578 spin_unlock_irq(lock
);
580 /* for synchronous bio-based driver finish in-flight integrity i/o */
581 blk_flush_integrity();
583 /* @q won't process any more request, flush async actions */
584 del_timer_sync(&q
->backing_dev_info
.laptop_mode_wb_timer
);
588 blk_mq_free_queue(q
);
589 percpu_ref_exit(&q
->q_usage_counter
);
592 if (q
->queue_lock
!= &q
->__queue_lock
)
593 q
->queue_lock
= &q
->__queue_lock
;
594 spin_unlock_irq(lock
);
596 bdi_unregister(&q
->backing_dev_info
);
598 /* @q is and will stay empty, shutdown and put */
601 EXPORT_SYMBOL(blk_cleanup_queue
);
603 /* Allocate memory local to the request queue */
604 static void *alloc_request_struct(gfp_t gfp_mask
, void *data
)
606 int nid
= (int)(long)data
;
607 return kmem_cache_alloc_node(request_cachep
, gfp_mask
, nid
);
610 static void free_request_struct(void *element
, void *unused
)
612 kmem_cache_free(request_cachep
, element
);
615 int blk_init_rl(struct request_list
*rl
, struct request_queue
*q
,
618 if (unlikely(rl
->rq_pool
))
622 rl
->count
[BLK_RW_SYNC
] = rl
->count
[BLK_RW_ASYNC
] = 0;
623 rl
->starved
[BLK_RW_SYNC
] = rl
->starved
[BLK_RW_ASYNC
] = 0;
624 init_waitqueue_head(&rl
->wait
[BLK_RW_SYNC
]);
625 init_waitqueue_head(&rl
->wait
[BLK_RW_ASYNC
]);
627 rl
->rq_pool
= mempool_create_node(BLKDEV_MIN_RQ
, alloc_request_struct
,
629 (void *)(long)q
->node
, gfp_mask
,
637 void blk_exit_rl(struct request_list
*rl
)
640 mempool_destroy(rl
->rq_pool
);
643 struct request_queue
*blk_alloc_queue(gfp_t gfp_mask
)
645 return blk_alloc_queue_node(gfp_mask
, NUMA_NO_NODE
);
647 EXPORT_SYMBOL(blk_alloc_queue
);
649 int blk_queue_enter(struct request_queue
*q
, bool nowait
)
654 if (percpu_ref_tryget_live(&q
->q_usage_counter
))
660 ret
= wait_event_interruptible(q
->mq_freeze_wq
,
661 !atomic_read(&q
->mq_freeze_depth
) ||
663 if (blk_queue_dying(q
))
670 void blk_queue_exit(struct request_queue
*q
)
672 percpu_ref_put(&q
->q_usage_counter
);
675 static void blk_queue_usage_counter_release(struct percpu_ref
*ref
)
677 struct request_queue
*q
=
678 container_of(ref
, struct request_queue
, q_usage_counter
);
680 wake_up_all(&q
->mq_freeze_wq
);
683 static void blk_rq_timed_out_timer(unsigned long data
)
685 struct request_queue
*q
= (struct request_queue
*)data
;
687 kblockd_schedule_work(&q
->timeout_work
);
690 struct request_queue
*blk_alloc_queue_node(gfp_t gfp_mask
, int node_id
)
692 struct request_queue
*q
;
695 q
= kmem_cache_alloc_node(blk_requestq_cachep
,
696 gfp_mask
| __GFP_ZERO
, node_id
);
700 q
->id
= ida_simple_get(&blk_queue_ida
, 0, 0, gfp_mask
);
704 q
->bio_split
= bioset_create(BIO_POOL_SIZE
, 0);
708 q
->backing_dev_info
.ra_pages
=
709 (VM_MAX_READAHEAD
* 1024) / PAGE_CACHE_SIZE
;
710 q
->backing_dev_info
.capabilities
= BDI_CAP_CGROUP_WRITEBACK
;
711 q
->backing_dev_info
.name
= "block";
714 err
= bdi_init(&q
->backing_dev_info
);
718 setup_timer(&q
->backing_dev_info
.laptop_mode_wb_timer
,
719 laptop_mode_timer_fn
, (unsigned long) q
);
720 setup_timer(&q
->timeout
, blk_rq_timed_out_timer
, (unsigned long) q
);
721 INIT_LIST_HEAD(&q
->queue_head
);
722 INIT_LIST_HEAD(&q
->timeout_list
);
723 INIT_LIST_HEAD(&q
->icq_list
);
724 #ifdef CONFIG_BLK_CGROUP
725 INIT_LIST_HEAD(&q
->blkg_list
);
727 INIT_DELAYED_WORK(&q
->delay_work
, blk_delay_work
);
729 kobject_init(&q
->kobj
, &blk_queue_ktype
);
731 mutex_init(&q
->sysfs_lock
);
732 spin_lock_init(&q
->__queue_lock
);
735 * By default initialize queue_lock to internal lock and driver can
736 * override it later if need be.
738 q
->queue_lock
= &q
->__queue_lock
;
741 * A queue starts its life with bypass turned on to avoid
742 * unnecessary bypass on/off overhead and nasty surprises during
743 * init. The initial bypass will be finished when the queue is
744 * registered by blk_register_queue().
747 __set_bit(QUEUE_FLAG_BYPASS
, &q
->queue_flags
);
749 init_waitqueue_head(&q
->mq_freeze_wq
);
752 * Init percpu_ref in atomic mode so that it's faster to shutdown.
753 * See blk_register_queue() for details.
755 if (percpu_ref_init(&q
->q_usage_counter
,
756 blk_queue_usage_counter_release
,
757 PERCPU_REF_INIT_ATOMIC
, GFP_KERNEL
))
760 if (blkcg_init_queue(q
))
766 percpu_ref_exit(&q
->q_usage_counter
);
768 bdi_destroy(&q
->backing_dev_info
);
770 bioset_free(q
->bio_split
);
772 ida_simple_remove(&blk_queue_ida
, q
->id
);
774 kmem_cache_free(blk_requestq_cachep
, q
);
777 EXPORT_SYMBOL(blk_alloc_queue_node
);
780 * blk_init_queue - prepare a request queue for use with a block device
781 * @rfn: The function to be called to process requests that have been
782 * placed on the queue.
783 * @lock: Request queue spin lock
786 * If a block device wishes to use the standard request handling procedures,
787 * which sorts requests and coalesces adjacent requests, then it must
788 * call blk_init_queue(). The function @rfn will be called when there
789 * are requests on the queue that need to be processed. If the device
790 * supports plugging, then @rfn may not be called immediately when requests
791 * are available on the queue, but may be called at some time later instead.
792 * Plugged queues are generally unplugged when a buffer belonging to one
793 * of the requests on the queue is needed, or due to memory pressure.
795 * @rfn is not required, or even expected, to remove all requests off the
796 * queue, but only as many as it can handle at a time. If it does leave
797 * requests on the queue, it is responsible for arranging that the requests
798 * get dealt with eventually.
800 * The queue spin lock must be held while manipulating the requests on the
801 * request queue; this lock will be taken also from interrupt context, so irq
802 * disabling is needed for it.
804 * Function returns a pointer to the initialized request queue, or %NULL if
808 * blk_init_queue() must be paired with a blk_cleanup_queue() call
809 * when the block device is deactivated (such as at module unload).
812 struct request_queue
*blk_init_queue(request_fn_proc
*rfn
, spinlock_t
*lock
)
814 return blk_init_queue_node(rfn
, lock
, NUMA_NO_NODE
);
816 EXPORT_SYMBOL(blk_init_queue
);
818 struct request_queue
*
819 blk_init_queue_node(request_fn_proc
*rfn
, spinlock_t
*lock
, int node_id
)
821 struct request_queue
*uninit_q
, *q
;
823 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, node_id
);
827 q
= blk_init_allocated_queue(uninit_q
, rfn
, lock
);
829 blk_cleanup_queue(uninit_q
);
833 EXPORT_SYMBOL(blk_init_queue_node
);
835 static blk_qc_t
blk_queue_bio(struct request_queue
*q
, struct bio
*bio
);
837 struct request_queue
*
838 blk_init_allocated_queue(struct request_queue
*q
, request_fn_proc
*rfn
,
844 q
->fq
= blk_alloc_flush_queue(q
, NUMA_NO_NODE
, 0);
848 if (blk_init_rl(&q
->root_rl
, q
, GFP_KERNEL
))
851 INIT_WORK(&q
->timeout_work
, blk_timeout_work
);
853 q
->prep_rq_fn
= NULL
;
854 q
->unprep_rq_fn
= NULL
;
855 q
->queue_flags
|= QUEUE_FLAG_DEFAULT
;
857 /* Override internal queue lock with supplied lock pointer */
859 q
->queue_lock
= lock
;
862 * This also sets hw/phys segments, boundary and size
864 blk_queue_make_request(q
, blk_queue_bio
);
866 q
->sg_reserved_size
= INT_MAX
;
868 /* Protect q->elevator from elevator_change */
869 mutex_lock(&q
->sysfs_lock
);
872 if (elevator_init(q
, NULL
)) {
873 mutex_unlock(&q
->sysfs_lock
);
877 mutex_unlock(&q
->sysfs_lock
);
882 blk_free_flush_queue(q
->fq
);
885 EXPORT_SYMBOL(blk_init_allocated_queue
);
887 bool blk_get_queue(struct request_queue
*q
)
889 if (likely(!blk_queue_dying(q
))) {
896 EXPORT_SYMBOL(blk_get_queue
);
898 static inline void blk_free_request(struct request_list
*rl
, struct request
*rq
)
900 if (rq
->cmd_flags
& REQ_ELVPRIV
) {
901 elv_put_request(rl
->q
, rq
);
903 put_io_context(rq
->elv
.icq
->ioc
);
906 mempool_free(rq
, rl
->rq_pool
);
910 * ioc_batching returns true if the ioc is a valid batching request and
911 * should be given priority access to a request.
913 static inline int ioc_batching(struct request_queue
*q
, struct io_context
*ioc
)
919 * Make sure the process is able to allocate at least 1 request
920 * even if the batch times out, otherwise we could theoretically
923 return ioc
->nr_batch_requests
== q
->nr_batching
||
924 (ioc
->nr_batch_requests
> 0
925 && time_before(jiffies
, ioc
->last_waited
+ BLK_BATCH_TIME
));
929 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
930 * will cause the process to be a "batcher" on all queues in the system. This
931 * is the behaviour we want though - once it gets a wakeup it should be given
934 static void ioc_set_batching(struct request_queue
*q
, struct io_context
*ioc
)
936 if (!ioc
|| ioc_batching(q
, ioc
))
939 ioc
->nr_batch_requests
= q
->nr_batching
;
940 ioc
->last_waited
= jiffies
;
943 static void __freed_request(struct request_list
*rl
, int sync
)
945 struct request_queue
*q
= rl
->q
;
947 if (rl
->count
[sync
] < queue_congestion_off_threshold(q
))
948 blk_clear_congested(rl
, sync
);
950 if (rl
->count
[sync
] + 1 <= q
->nr_requests
) {
951 if (waitqueue_active(&rl
->wait
[sync
]))
952 wake_up(&rl
->wait
[sync
]);
954 blk_clear_rl_full(rl
, sync
);
959 * A request has just been released. Account for it, update the full and
960 * congestion status, wake up any waiters. Called under q->queue_lock.
962 static void freed_request(struct request_list
*rl
, unsigned int flags
)
964 struct request_queue
*q
= rl
->q
;
965 int sync
= rw_is_sync(flags
);
969 if (flags
& REQ_ELVPRIV
)
972 __freed_request(rl
, sync
);
974 if (unlikely(rl
->starved
[sync
^ 1]))
975 __freed_request(rl
, sync
^ 1);
978 int blk_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
980 struct request_list
*rl
;
981 int on_thresh
, off_thresh
;
983 spin_lock_irq(q
->queue_lock
);
985 blk_queue_congestion_threshold(q
);
986 on_thresh
= queue_congestion_on_threshold(q
);
987 off_thresh
= queue_congestion_off_threshold(q
);
989 blk_queue_for_each_rl(rl
, q
) {
990 if (rl
->count
[BLK_RW_SYNC
] >= on_thresh
)
991 blk_set_congested(rl
, BLK_RW_SYNC
);
992 else if (rl
->count
[BLK_RW_SYNC
] < off_thresh
)
993 blk_clear_congested(rl
, BLK_RW_SYNC
);
995 if (rl
->count
[BLK_RW_ASYNC
] >= on_thresh
)
996 blk_set_congested(rl
, BLK_RW_ASYNC
);
997 else if (rl
->count
[BLK_RW_ASYNC
] < off_thresh
)
998 blk_clear_congested(rl
, BLK_RW_ASYNC
);
1000 if (rl
->count
[BLK_RW_SYNC
] >= q
->nr_requests
) {
1001 blk_set_rl_full(rl
, BLK_RW_SYNC
);
1003 blk_clear_rl_full(rl
, BLK_RW_SYNC
);
1004 wake_up(&rl
->wait
[BLK_RW_SYNC
]);
1007 if (rl
->count
[BLK_RW_ASYNC
] >= q
->nr_requests
) {
1008 blk_set_rl_full(rl
, BLK_RW_ASYNC
);
1010 blk_clear_rl_full(rl
, BLK_RW_ASYNC
);
1011 wake_up(&rl
->wait
[BLK_RW_ASYNC
]);
1015 spin_unlock_irq(q
->queue_lock
);
1020 * Determine if elevator data should be initialized when allocating the
1021 * request associated with @bio.
1023 static bool blk_rq_should_init_elevator(struct bio
*bio
)
1029 * Flush requests do not use the elevator so skip initialization.
1030 * This allows a request to share the flush and elevator data.
1032 if (bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
))
1039 * rq_ioc - determine io_context for request allocation
1040 * @bio: request being allocated is for this bio (can be %NULL)
1042 * Determine io_context to use for request allocation for @bio. May return
1043 * %NULL if %current->io_context doesn't exist.
1045 static struct io_context
*rq_ioc(struct bio
*bio
)
1047 #ifdef CONFIG_BLK_CGROUP
1048 if (bio
&& bio
->bi_ioc
)
1051 return current
->io_context
;
1055 * __get_request - get a free request
1056 * @rl: request list to allocate from
1057 * @rw_flags: RW and SYNC flags
1058 * @bio: bio to allocate request for (can be %NULL)
1059 * @gfp_mask: allocation mask
1061 * Get a free request from @q. This function may fail under memory
1062 * pressure or if @q is dead.
1064 * Must be called with @q->queue_lock held and,
1065 * Returns ERR_PTR on failure, with @q->queue_lock held.
1066 * Returns request pointer on success, with @q->queue_lock *not held*.
1068 static struct request
*__get_request(struct request_list
*rl
, int rw_flags
,
1069 struct bio
*bio
, gfp_t gfp_mask
)
1071 struct request_queue
*q
= rl
->q
;
1073 struct elevator_type
*et
= q
->elevator
->type
;
1074 struct io_context
*ioc
= rq_ioc(bio
);
1075 struct io_cq
*icq
= NULL
;
1076 const bool is_sync
= rw_is_sync(rw_flags
) != 0;
1079 if (unlikely(blk_queue_dying(q
)))
1080 return ERR_PTR(-ENODEV
);
1082 may_queue
= elv_may_queue(q
, rw_flags
);
1083 if (may_queue
== ELV_MQUEUE_NO
)
1086 if (rl
->count
[is_sync
]+1 >= queue_congestion_on_threshold(q
)) {
1087 if (rl
->count
[is_sync
]+1 >= q
->nr_requests
) {
1089 * The queue will fill after this allocation, so set
1090 * it as full, and mark this process as "batching".
1091 * This process will be allowed to complete a batch of
1092 * requests, others will be blocked.
1094 if (!blk_rl_full(rl
, is_sync
)) {
1095 ioc_set_batching(q
, ioc
);
1096 blk_set_rl_full(rl
, is_sync
);
1098 if (may_queue
!= ELV_MQUEUE_MUST
1099 && !ioc_batching(q
, ioc
)) {
1101 * The queue is full and the allocating
1102 * process is not a "batcher", and not
1103 * exempted by the IO scheduler
1105 return ERR_PTR(-ENOMEM
);
1109 blk_set_congested(rl
, is_sync
);
1113 * Only allow batching queuers to allocate up to 50% over the defined
1114 * limit of requests, otherwise we could have thousands of requests
1115 * allocated with any setting of ->nr_requests
1117 if (rl
->count
[is_sync
] >= (3 * q
->nr_requests
/ 2))
1118 return ERR_PTR(-ENOMEM
);
1120 q
->nr_rqs
[is_sync
]++;
1121 rl
->count
[is_sync
]++;
1122 rl
->starved
[is_sync
] = 0;
1125 * Decide whether the new request will be managed by elevator. If
1126 * so, mark @rw_flags and increment elvpriv. Non-zero elvpriv will
1127 * prevent the current elevator from being destroyed until the new
1128 * request is freed. This guarantees icq's won't be destroyed and
1129 * makes creating new ones safe.
1131 * Also, lookup icq while holding queue_lock. If it doesn't exist,
1132 * it will be created after releasing queue_lock.
1134 if (blk_rq_should_init_elevator(bio
) && !blk_queue_bypass(q
)) {
1135 rw_flags
|= REQ_ELVPRIV
;
1136 q
->nr_rqs_elvpriv
++;
1137 if (et
->icq_cache
&& ioc
)
1138 icq
= ioc_lookup_icq(ioc
, q
);
1141 if (blk_queue_io_stat(q
))
1142 rw_flags
|= REQ_IO_STAT
;
1143 spin_unlock_irq(q
->queue_lock
);
1145 /* allocate and init request */
1146 rq
= mempool_alloc(rl
->rq_pool
, gfp_mask
);
1151 blk_rq_set_rl(rq
, rl
);
1152 rq
->cmd_flags
= rw_flags
| REQ_ALLOCED
;
1155 if (rw_flags
& REQ_ELVPRIV
) {
1156 if (unlikely(et
->icq_cache
&& !icq
)) {
1158 icq
= ioc_create_icq(ioc
, q
, gfp_mask
);
1164 if (unlikely(elv_set_request(q
, rq
, bio
, gfp_mask
)))
1167 /* @rq->elv.icq holds io_context until @rq is freed */
1169 get_io_context(icq
->ioc
);
1173 * ioc may be NULL here, and ioc_batching will be false. That's
1174 * OK, if the queue is under the request limit then requests need
1175 * not count toward the nr_batch_requests limit. There will always
1176 * be some limit enforced by BLK_BATCH_TIME.
1178 if (ioc_batching(q
, ioc
))
1179 ioc
->nr_batch_requests
--;
1181 trace_block_getrq(q
, bio
, rw_flags
& 1);
1186 * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed
1187 * and may fail indefinitely under memory pressure and thus
1188 * shouldn't stall IO. Treat this request as !elvpriv. This will
1189 * disturb iosched and blkcg but weird is bettern than dead.
1191 printk_ratelimited(KERN_WARNING
"%s: dev %s: request aux data allocation failed, iosched may be disturbed\n",
1192 __func__
, dev_name(q
->backing_dev_info
.dev
));
1194 rq
->cmd_flags
&= ~REQ_ELVPRIV
;
1197 spin_lock_irq(q
->queue_lock
);
1198 q
->nr_rqs_elvpriv
--;
1199 spin_unlock_irq(q
->queue_lock
);
1204 * Allocation failed presumably due to memory. Undo anything we
1205 * might have messed up.
1207 * Allocating task should really be put onto the front of the wait
1208 * queue, but this is pretty rare.
1210 spin_lock_irq(q
->queue_lock
);
1211 freed_request(rl
, rw_flags
);
1214 * in the very unlikely event that allocation failed and no
1215 * requests for this direction was pending, mark us starved so that
1216 * freeing of a request in the other direction will notice
1217 * us. another possible fix would be to split the rq mempool into
1221 if (unlikely(rl
->count
[is_sync
] == 0))
1222 rl
->starved
[is_sync
] = 1;
1223 return ERR_PTR(-ENOMEM
);
1227 * get_request - get a free request
1228 * @q: request_queue to allocate request from
1229 * @rw_flags: RW and SYNC flags
1230 * @bio: bio to allocate request for (can be %NULL)
1231 * @gfp_mask: allocation mask
1233 * Get a free request from @q. If %__GFP_DIRECT_RECLAIM is set in @gfp_mask,
1234 * this function keeps retrying under memory pressure and fails iff @q is dead.
1236 * Must be called with @q->queue_lock held and,
1237 * Returns ERR_PTR on failure, with @q->queue_lock held.
1238 * Returns request pointer on success, with @q->queue_lock *not held*.
1240 static struct request
*get_request(struct request_queue
*q
, int rw_flags
,
1241 struct bio
*bio
, gfp_t gfp_mask
)
1243 const bool is_sync
= rw_is_sync(rw_flags
) != 0;
1245 struct request_list
*rl
;
1248 rl
= blk_get_rl(q
, bio
); /* transferred to @rq on success */
1250 rq
= __get_request(rl
, rw_flags
, bio
, gfp_mask
);
1254 if (!gfpflags_allow_blocking(gfp_mask
) || unlikely(blk_queue_dying(q
))) {
1259 /* wait on @rl and retry */
1260 prepare_to_wait_exclusive(&rl
->wait
[is_sync
], &wait
,
1261 TASK_UNINTERRUPTIBLE
);
1263 trace_block_sleeprq(q
, bio
, rw_flags
& 1);
1265 spin_unlock_irq(q
->queue_lock
);
1269 * After sleeping, we become a "batching" process and will be able
1270 * to allocate at least one request, and up to a big batch of them
1271 * for a small period time. See ioc_batching, ioc_set_batching
1273 ioc_set_batching(q
, current
->io_context
);
1275 spin_lock_irq(q
->queue_lock
);
1276 finish_wait(&rl
->wait
[is_sync
], &wait
);
1281 static struct request
*blk_old_get_request(struct request_queue
*q
, int rw
,
1286 BUG_ON(rw
!= READ
&& rw
!= WRITE
);
1288 /* create ioc upfront */
1289 create_io_context(gfp_mask
, q
->node
);
1291 spin_lock_irq(q
->queue_lock
);
1292 rq
= get_request(q
, rw
, NULL
, gfp_mask
);
1294 spin_unlock_irq(q
->queue_lock
);
1295 /* q->queue_lock is unlocked at this point */
1300 struct request
*blk_get_request(struct request_queue
*q
, int rw
, gfp_t gfp_mask
)
1303 return blk_mq_alloc_request(q
, rw
,
1304 (gfp_mask
& __GFP_DIRECT_RECLAIM
) ?
1305 0 : BLK_MQ_REQ_NOWAIT
);
1307 return blk_old_get_request(q
, rw
, gfp_mask
);
1309 EXPORT_SYMBOL(blk_get_request
);
1312 * blk_make_request - given a bio, allocate a corresponding struct request.
1313 * @q: target request queue
1314 * @bio: The bio describing the memory mappings that will be submitted for IO.
1315 * It may be a chained-bio properly constructed by block/bio layer.
1316 * @gfp_mask: gfp flags to be used for memory allocation
1318 * blk_make_request is the parallel of generic_make_request for BLOCK_PC
1319 * type commands. Where the struct request needs to be farther initialized by
1320 * the caller. It is passed a &struct bio, which describes the memory info of
1323 * The caller of blk_make_request must make sure that bi_io_vec
1324 * are set to describe the memory buffers. That bio_data_dir() will return
1325 * the needed direction of the request. (And all bio's in the passed bio-chain
1326 * are properly set accordingly)
1328 * If called under none-sleepable conditions, mapped bio buffers must not
1329 * need bouncing, by calling the appropriate masked or flagged allocator,
1330 * suitable for the target device. Otherwise the call to blk_queue_bounce will
1333 * WARNING: When allocating/cloning a bio-chain, careful consideration should be
1334 * given to how you allocate bios. In particular, you cannot use
1335 * __GFP_DIRECT_RECLAIM for anything but the first bio in the chain. Otherwise
1336 * you risk waiting for IO completion of a bio that hasn't been submitted yet,
1337 * thus resulting in a deadlock. Alternatively bios should be allocated using
1338 * bio_kmalloc() instead of bio_alloc(), as that avoids the mempool deadlock.
1339 * If possible a big IO should be split into smaller parts when allocation
1340 * fails. Partial allocation should not be an error, or you risk a live-lock.
1342 struct request
*blk_make_request(struct request_queue
*q
, struct bio
*bio
,
1345 struct request
*rq
= blk_get_request(q
, bio_data_dir(bio
), gfp_mask
);
1350 blk_rq_set_block_pc(rq
);
1353 struct bio
*bounce_bio
= bio
;
1356 blk_queue_bounce(q
, &bounce_bio
);
1357 ret
= blk_rq_append_bio(q
, rq
, bounce_bio
);
1358 if (unlikely(ret
)) {
1359 blk_put_request(rq
);
1360 return ERR_PTR(ret
);
1366 EXPORT_SYMBOL(blk_make_request
);
1369 * blk_rq_set_block_pc - initialize a request to type BLOCK_PC
1370 * @rq: request to be initialized
1373 void blk_rq_set_block_pc(struct request
*rq
)
1375 rq
->cmd_type
= REQ_TYPE_BLOCK_PC
;
1377 rq
->__sector
= (sector_t
) -1;
1378 rq
->bio
= rq
->biotail
= NULL
;
1379 memset(rq
->__cmd
, 0, sizeof(rq
->__cmd
));
1381 EXPORT_SYMBOL(blk_rq_set_block_pc
);
1384 * blk_requeue_request - put a request back on queue
1385 * @q: request queue where request should be inserted
1386 * @rq: request to be inserted
1389 * Drivers often keep queueing requests until the hardware cannot accept
1390 * more, when that condition happens we need to put the request back
1391 * on the queue. Must be called with queue lock held.
1393 void blk_requeue_request(struct request_queue
*q
, struct request
*rq
)
1395 blk_delete_timer(rq
);
1396 blk_clear_rq_complete(rq
);
1397 trace_block_rq_requeue(q
, rq
);
1399 if (rq
->cmd_flags
& REQ_QUEUED
)
1400 blk_queue_end_tag(q
, rq
);
1402 BUG_ON(blk_queued_rq(rq
));
1404 elv_requeue_request(q
, rq
);
1406 EXPORT_SYMBOL(blk_requeue_request
);
1408 static void add_acct_request(struct request_queue
*q
, struct request
*rq
,
1411 blk_account_io_start(rq
, true);
1412 __elv_add_request(q
, rq
, where
);
1415 static void part_round_stats_single(int cpu
, struct hd_struct
*part
,
1420 if (now
== part
->stamp
)
1423 inflight
= part_in_flight(part
);
1425 __part_stat_add(cpu
, part
, time_in_queue
,
1426 inflight
* (now
- part
->stamp
));
1427 __part_stat_add(cpu
, part
, io_ticks
, (now
- part
->stamp
));
1433 * part_round_stats() - Round off the performance stats on a struct disk_stats.
1434 * @cpu: cpu number for stats access
1435 * @part: target partition
1437 * The average IO queue length and utilisation statistics are maintained
1438 * by observing the current state of the queue length and the amount of
1439 * time it has been in this state for.
1441 * Normally, that accounting is done on IO completion, but that can result
1442 * in more than a second's worth of IO being accounted for within any one
1443 * second, leading to >100% utilisation. To deal with that, we call this
1444 * function to do a round-off before returning the results when reading
1445 * /proc/diskstats. This accounts immediately for all queue usage up to
1446 * the current jiffies and restarts the counters again.
1448 void part_round_stats(int cpu
, struct hd_struct
*part
)
1450 unsigned long now
= jiffies
;
1453 part_round_stats_single(cpu
, &part_to_disk(part
)->part0
, now
);
1454 part_round_stats_single(cpu
, part
, now
);
1456 EXPORT_SYMBOL_GPL(part_round_stats
);
1459 static void blk_pm_put_request(struct request
*rq
)
1461 if (rq
->q
->dev
&& !(rq
->cmd_flags
& REQ_PM
) && !--rq
->q
->nr_pending
)
1462 pm_runtime_mark_last_busy(rq
->q
->dev
);
1465 static inline void blk_pm_put_request(struct request
*rq
) {}
1469 * queue lock must be held
1471 void __blk_put_request(struct request_queue
*q
, struct request
*req
)
1477 blk_mq_free_request(req
);
1481 blk_pm_put_request(req
);
1483 elv_completed_request(q
, req
);
1485 /* this is a bio leak */
1486 WARN_ON(req
->bio
!= NULL
);
1489 * Request may not have originated from ll_rw_blk. if not,
1490 * it didn't come out of our reserved rq pools
1492 if (req
->cmd_flags
& REQ_ALLOCED
) {
1493 unsigned int flags
= req
->cmd_flags
;
1494 struct request_list
*rl
= blk_rq_rl(req
);
1496 BUG_ON(!list_empty(&req
->queuelist
));
1497 BUG_ON(ELV_ON_HASH(req
));
1499 blk_free_request(rl
, req
);
1500 freed_request(rl
, flags
);
1504 EXPORT_SYMBOL_GPL(__blk_put_request
);
1506 void blk_put_request(struct request
*req
)
1508 struct request_queue
*q
= req
->q
;
1511 blk_mq_free_request(req
);
1513 unsigned long flags
;
1515 spin_lock_irqsave(q
->queue_lock
, flags
);
1516 __blk_put_request(q
, req
);
1517 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1520 EXPORT_SYMBOL(blk_put_request
);
1523 * blk_add_request_payload - add a payload to a request
1524 * @rq: request to update
1525 * @page: page backing the payload
1526 * @len: length of the payload.
1528 * This allows to later add a payload to an already submitted request by
1529 * a block driver. The driver needs to take care of freeing the payload
1532 * Note that this is a quite horrible hack and nothing but handling of
1533 * discard requests should ever use it.
1535 void blk_add_request_payload(struct request
*rq
, struct page
*page
,
1538 struct bio
*bio
= rq
->bio
;
1540 bio
->bi_io_vec
->bv_page
= page
;
1541 bio
->bi_io_vec
->bv_offset
= 0;
1542 bio
->bi_io_vec
->bv_len
= len
;
1544 bio
->bi_iter
.bi_size
= len
;
1546 bio
->bi_phys_segments
= 1;
1548 rq
->__data_len
= rq
->resid_len
= len
;
1549 rq
->nr_phys_segments
= 1;
1551 EXPORT_SYMBOL_GPL(blk_add_request_payload
);
1553 bool bio_attempt_back_merge(struct request_queue
*q
, struct request
*req
,
1556 const int ff
= bio
->bi_rw
& REQ_FAILFAST_MASK
;
1558 if (!ll_back_merge_fn(q
, req
, bio
))
1561 trace_block_bio_backmerge(q
, req
, bio
);
1563 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
1564 blk_rq_set_mixed_merge(req
);
1566 req
->biotail
->bi_next
= bio
;
1568 req
->__data_len
+= bio
->bi_iter
.bi_size
;
1569 req
->ioprio
= ioprio_best(req
->ioprio
, bio_prio(bio
));
1571 blk_account_io_start(req
, false);
1575 bool bio_attempt_front_merge(struct request_queue
*q
, struct request
*req
,
1578 const int ff
= bio
->bi_rw
& REQ_FAILFAST_MASK
;
1580 if (!ll_front_merge_fn(q
, req
, bio
))
1583 trace_block_bio_frontmerge(q
, req
, bio
);
1585 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
1586 blk_rq_set_mixed_merge(req
);
1588 bio
->bi_next
= req
->bio
;
1591 req
->__sector
= bio
->bi_iter
.bi_sector
;
1592 req
->__data_len
+= bio
->bi_iter
.bi_size
;
1593 req
->ioprio
= ioprio_best(req
->ioprio
, bio_prio(bio
));
1595 blk_account_io_start(req
, false);
1600 * blk_attempt_plug_merge - try to merge with %current's plugged list
1601 * @q: request_queue new bio is being queued at
1602 * @bio: new bio being queued
1603 * @request_count: out parameter for number of traversed plugged requests
1604 * @same_queue_rq: pointer to &struct request that gets filled in when
1605 * another request associated with @q is found on the plug list
1606 * (optional, may be %NULL)
1608 * Determine whether @bio being queued on @q can be merged with a request
1609 * on %current's plugged list. Returns %true if merge was successful,
1612 * Plugging coalesces IOs from the same issuer for the same purpose without
1613 * going through @q->queue_lock. As such it's more of an issuing mechanism
1614 * than scheduling, and the request, while may have elvpriv data, is not
1615 * added on the elevator at this point. In addition, we don't have
1616 * reliable access to the elevator outside queue lock. Only check basic
1617 * merging parameters without querying the elevator.
1619 * Caller must ensure !blk_queue_nomerges(q) beforehand.
1621 bool blk_attempt_plug_merge(struct request_queue
*q
, struct bio
*bio
,
1622 unsigned int *request_count
,
1623 struct request
**same_queue_rq
)
1625 struct blk_plug
*plug
;
1628 struct list_head
*plug_list
;
1630 plug
= current
->plug
;
1636 plug_list
= &plug
->mq_list
;
1638 plug_list
= &plug
->list
;
1640 list_for_each_entry_reverse(rq
, plug_list
, queuelist
) {
1646 * Only blk-mq multiple hardware queues case checks the
1647 * rq in the same queue, there should be only one such
1651 *same_queue_rq
= rq
;
1654 if (rq
->q
!= q
|| !blk_rq_merge_ok(rq
, bio
))
1657 el_ret
= blk_try_merge(rq
, bio
);
1658 if (el_ret
== ELEVATOR_BACK_MERGE
) {
1659 ret
= bio_attempt_back_merge(q
, rq
, bio
);
1662 } else if (el_ret
== ELEVATOR_FRONT_MERGE
) {
1663 ret
= bio_attempt_front_merge(q
, rq
, bio
);
1672 unsigned int blk_plug_queued_count(struct request_queue
*q
)
1674 struct blk_plug
*plug
;
1676 struct list_head
*plug_list
;
1677 unsigned int ret
= 0;
1679 plug
= current
->plug
;
1684 plug_list
= &plug
->mq_list
;
1686 plug_list
= &plug
->list
;
1688 list_for_each_entry(rq
, plug_list
, queuelist
) {
1696 void init_request_from_bio(struct request
*req
, struct bio
*bio
)
1698 req
->cmd_type
= REQ_TYPE_FS
;
1700 req
->cmd_flags
|= bio
->bi_rw
& REQ_COMMON_MASK
;
1701 if (bio
->bi_rw
& REQ_RAHEAD
)
1702 req
->cmd_flags
|= REQ_FAILFAST_MASK
;
1705 req
->__sector
= bio
->bi_iter
.bi_sector
;
1706 req
->ioprio
= bio_prio(bio
);
1707 blk_rq_bio_prep(req
->q
, req
, bio
);
1710 static blk_qc_t
blk_queue_bio(struct request_queue
*q
, struct bio
*bio
)
1712 const bool sync
= !!(bio
->bi_rw
& REQ_SYNC
);
1713 struct blk_plug
*plug
;
1714 int el_ret
, rw_flags
, where
= ELEVATOR_INSERT_SORT
;
1715 struct request
*req
;
1716 unsigned int request_count
= 0;
1719 * low level driver can indicate that it wants pages above a
1720 * certain limit bounced to low memory (ie for highmem, or even
1721 * ISA dma in theory)
1723 blk_queue_bounce(q
, &bio
);
1725 blk_queue_split(q
, &bio
, q
->bio_split
);
1727 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1728 bio
->bi_error
= -EIO
;
1730 return BLK_QC_T_NONE
;
1733 if (bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
)) {
1734 spin_lock_irq(q
->queue_lock
);
1735 where
= ELEVATOR_INSERT_FLUSH
;
1740 * Check if we can merge with the plugged list before grabbing
1743 if (!blk_queue_nomerges(q
)) {
1744 if (blk_attempt_plug_merge(q
, bio
, &request_count
, NULL
))
1745 return BLK_QC_T_NONE
;
1747 request_count
= blk_plug_queued_count(q
);
1749 spin_lock_irq(q
->queue_lock
);
1751 el_ret
= elv_merge(q
, &req
, bio
);
1752 if (el_ret
== ELEVATOR_BACK_MERGE
) {
1753 if (bio_attempt_back_merge(q
, req
, bio
)) {
1754 elv_bio_merged(q
, req
, bio
);
1755 if (!attempt_back_merge(q
, req
))
1756 elv_merged_request(q
, req
, el_ret
);
1759 } else if (el_ret
== ELEVATOR_FRONT_MERGE
) {
1760 if (bio_attempt_front_merge(q
, req
, bio
)) {
1761 elv_bio_merged(q
, req
, bio
);
1762 if (!attempt_front_merge(q
, req
))
1763 elv_merged_request(q
, req
, el_ret
);
1770 * This sync check and mask will be re-done in init_request_from_bio(),
1771 * but we need to set it earlier to expose the sync flag to the
1772 * rq allocator and io schedulers.
1774 rw_flags
= bio_data_dir(bio
);
1776 rw_flags
|= REQ_SYNC
;
1779 * Grab a free request. This is might sleep but can not fail.
1780 * Returns with the queue unlocked.
1782 req
= get_request(q
, rw_flags
, bio
, GFP_NOIO
);
1784 bio
->bi_error
= PTR_ERR(req
);
1790 * After dropping the lock and possibly sleeping here, our request
1791 * may now be mergeable after it had proven unmergeable (above).
1792 * We don't worry about that case for efficiency. It won't happen
1793 * often, and the elevators are able to handle it.
1795 init_request_from_bio(req
, bio
);
1797 if (test_bit(QUEUE_FLAG_SAME_COMP
, &q
->queue_flags
))
1798 req
->cpu
= raw_smp_processor_id();
1800 plug
= current
->plug
;
1803 * If this is the first request added after a plug, fire
1807 trace_block_plug(q
);
1809 if (request_count
>= BLK_MAX_REQUEST_COUNT
) {
1810 blk_flush_plug_list(plug
, false);
1811 trace_block_plug(q
);
1814 list_add_tail(&req
->queuelist
, &plug
->list
);
1815 blk_account_io_start(req
, true);
1817 spin_lock_irq(q
->queue_lock
);
1818 add_acct_request(q
, req
, where
);
1821 spin_unlock_irq(q
->queue_lock
);
1824 return BLK_QC_T_NONE
;
1828 * If bio->bi_dev is a partition, remap the location
1830 static inline void blk_partition_remap(struct bio
*bio
)
1832 struct block_device
*bdev
= bio
->bi_bdev
;
1834 if (bio_sectors(bio
) && bdev
!= bdev
->bd_contains
) {
1835 struct hd_struct
*p
= bdev
->bd_part
;
1837 bio
->bi_iter
.bi_sector
+= p
->start_sect
;
1838 bio
->bi_bdev
= bdev
->bd_contains
;
1840 trace_block_bio_remap(bdev_get_queue(bio
->bi_bdev
), bio
,
1842 bio
->bi_iter
.bi_sector
- p
->start_sect
);
1846 static void handle_bad_sector(struct bio
*bio
)
1848 char b
[BDEVNAME_SIZE
];
1850 printk(KERN_INFO
"attempt to access beyond end of device\n");
1851 printk(KERN_INFO
"%s: rw=%ld, want=%Lu, limit=%Lu\n",
1852 bdevname(bio
->bi_bdev
, b
),
1854 (unsigned long long)bio_end_sector(bio
),
1855 (long long)(i_size_read(bio
->bi_bdev
->bd_inode
) >> 9));
1858 #ifdef CONFIG_FAIL_MAKE_REQUEST
1860 static DECLARE_FAULT_ATTR(fail_make_request
);
1862 static int __init
setup_fail_make_request(char *str
)
1864 return setup_fault_attr(&fail_make_request
, str
);
1866 __setup("fail_make_request=", setup_fail_make_request
);
1868 static bool should_fail_request(struct hd_struct
*part
, unsigned int bytes
)
1870 return part
->make_it_fail
&& should_fail(&fail_make_request
, bytes
);
1873 static int __init
fail_make_request_debugfs(void)
1875 struct dentry
*dir
= fault_create_debugfs_attr("fail_make_request",
1876 NULL
, &fail_make_request
);
1878 return PTR_ERR_OR_ZERO(dir
);
1881 late_initcall(fail_make_request_debugfs
);
1883 #else /* CONFIG_FAIL_MAKE_REQUEST */
1885 static inline bool should_fail_request(struct hd_struct
*part
,
1891 #endif /* CONFIG_FAIL_MAKE_REQUEST */
1894 * Check whether this bio extends beyond the end of the device.
1896 static inline int bio_check_eod(struct bio
*bio
, unsigned int nr_sectors
)
1903 /* Test device or partition size, when known. */
1904 maxsector
= i_size_read(bio
->bi_bdev
->bd_inode
) >> 9;
1906 sector_t sector
= bio
->bi_iter
.bi_sector
;
1908 if (maxsector
< nr_sectors
|| maxsector
- nr_sectors
< sector
) {
1910 * This may well happen - the kernel calls bread()
1911 * without checking the size of the device, e.g., when
1912 * mounting a device.
1914 handle_bad_sector(bio
);
1922 static noinline_for_stack
bool
1923 generic_make_request_checks(struct bio
*bio
)
1925 struct request_queue
*q
;
1926 int nr_sectors
= bio_sectors(bio
);
1928 char b
[BDEVNAME_SIZE
];
1929 struct hd_struct
*part
;
1933 if (bio_check_eod(bio
, nr_sectors
))
1936 q
= bdev_get_queue(bio
->bi_bdev
);
1939 "generic_make_request: Trying to access "
1940 "nonexistent block-device %s (%Lu)\n",
1941 bdevname(bio
->bi_bdev
, b
),
1942 (long long) bio
->bi_iter
.bi_sector
);
1946 part
= bio
->bi_bdev
->bd_part
;
1947 if (should_fail_request(part
, bio
->bi_iter
.bi_size
) ||
1948 should_fail_request(&part_to_disk(part
)->part0
,
1949 bio
->bi_iter
.bi_size
))
1953 * If this device has partitions, remap block n
1954 * of partition p to block n+start(p) of the disk.
1956 blk_partition_remap(bio
);
1958 if (bio_check_eod(bio
, nr_sectors
))
1962 * Filter flush bio's early so that make_request based
1963 * drivers without flush support don't have to worry
1966 if ((bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
)) && !q
->flush_flags
) {
1967 bio
->bi_rw
&= ~(REQ_FLUSH
| REQ_FUA
);
1974 if ((bio
->bi_rw
& REQ_DISCARD
) &&
1975 (!blk_queue_discard(q
) ||
1976 ((bio
->bi_rw
& REQ_SECURE
) && !blk_queue_secdiscard(q
)))) {
1981 if (bio
->bi_rw
& REQ_WRITE_SAME
&& !bdev_write_same(bio
->bi_bdev
)) {
1987 * Various block parts want %current->io_context and lazy ioc
1988 * allocation ends up trading a lot of pain for a small amount of
1989 * memory. Just allocate it upfront. This may fail and block
1990 * layer knows how to live with it.
1992 create_io_context(GFP_ATOMIC
, q
->node
);
1994 if (!blkcg_bio_issue_check(q
, bio
))
1997 trace_block_bio_queue(q
, bio
);
2001 bio
->bi_error
= err
;
2007 * generic_make_request - hand a buffer to its device driver for I/O
2008 * @bio: The bio describing the location in memory and on the device.
2010 * generic_make_request() is used to make I/O requests of block
2011 * devices. It is passed a &struct bio, which describes the I/O that needs
2014 * generic_make_request() does not return any status. The
2015 * success/failure status of the request, along with notification of
2016 * completion, is delivered asynchronously through the bio->bi_end_io
2017 * function described (one day) else where.
2019 * The caller of generic_make_request must make sure that bi_io_vec
2020 * are set to describe the memory buffer, and that bi_dev and bi_sector are
2021 * set to describe the device address, and the
2022 * bi_end_io and optionally bi_private are set to describe how
2023 * completion notification should be signaled.
2025 * generic_make_request and the drivers it calls may use bi_next if this
2026 * bio happens to be merged with someone else, and may resubmit the bio to
2027 * a lower device by calling into generic_make_request recursively, which
2028 * means the bio should NOT be touched after the call to ->make_request_fn.
2030 blk_qc_t
generic_make_request(struct bio
*bio
)
2032 struct bio_list bio_list_on_stack
;
2033 blk_qc_t ret
= BLK_QC_T_NONE
;
2035 if (!generic_make_request_checks(bio
))
2039 * We only want one ->make_request_fn to be active at a time, else
2040 * stack usage with stacked devices could be a problem. So use
2041 * current->bio_list to keep a list of requests submited by a
2042 * make_request_fn function. current->bio_list is also used as a
2043 * flag to say if generic_make_request is currently active in this
2044 * task or not. If it is NULL, then no make_request is active. If
2045 * it is non-NULL, then a make_request is active, and new requests
2046 * should be added at the tail
2048 if (current
->bio_list
) {
2049 bio_list_add(current
->bio_list
, bio
);
2053 /* following loop may be a bit non-obvious, and so deserves some
2055 * Before entering the loop, bio->bi_next is NULL (as all callers
2056 * ensure that) so we have a list with a single bio.
2057 * We pretend that we have just taken it off a longer list, so
2058 * we assign bio_list to a pointer to the bio_list_on_stack,
2059 * thus initialising the bio_list of new bios to be
2060 * added. ->make_request() may indeed add some more bios
2061 * through a recursive call to generic_make_request. If it
2062 * did, we find a non-NULL value in bio_list and re-enter the loop
2063 * from the top. In this case we really did just take the bio
2064 * of the top of the list (no pretending) and so remove it from
2065 * bio_list, and call into ->make_request() again.
2067 BUG_ON(bio
->bi_next
);
2068 bio_list_init(&bio_list_on_stack
);
2069 current
->bio_list
= &bio_list_on_stack
;
2071 struct request_queue
*q
= bdev_get_queue(bio
->bi_bdev
);
2073 if (likely(blk_queue_enter(q
, false) == 0)) {
2074 ret
= q
->make_request_fn(q
, bio
);
2078 bio
= bio_list_pop(current
->bio_list
);
2080 struct bio
*bio_next
= bio_list_pop(current
->bio_list
);
2086 current
->bio_list
= NULL
; /* deactivate */
2091 EXPORT_SYMBOL(generic_make_request
);
2094 * submit_bio - submit a bio to the block device layer for I/O
2095 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
2096 * @bio: The &struct bio which describes the I/O
2098 * submit_bio() is very similar in purpose to generic_make_request(), and
2099 * uses that function to do most of the work. Both are fairly rough
2100 * interfaces; @bio must be presetup and ready for I/O.
2103 blk_qc_t
submit_bio(int rw
, struct bio
*bio
)
2108 * If it's a regular read/write or a barrier with data attached,
2109 * go through the normal accounting stuff before submission.
2111 if (bio_has_data(bio
)) {
2114 if (unlikely(rw
& REQ_WRITE_SAME
))
2115 count
= bdev_logical_block_size(bio
->bi_bdev
) >> 9;
2117 count
= bio_sectors(bio
);
2120 count_vm_events(PGPGOUT
, count
);
2122 task_io_account_read(bio
->bi_iter
.bi_size
);
2123 count_vm_events(PGPGIN
, count
);
2126 if (unlikely(block_dump
)) {
2127 char b
[BDEVNAME_SIZE
];
2128 printk(KERN_DEBUG
"%s(%d): %s block %Lu on %s (%u sectors)\n",
2129 current
->comm
, task_pid_nr(current
),
2130 (rw
& WRITE
) ? "WRITE" : "READ",
2131 (unsigned long long)bio
->bi_iter
.bi_sector
,
2132 bdevname(bio
->bi_bdev
, b
),
2137 return generic_make_request(bio
);
2139 EXPORT_SYMBOL(submit_bio
);
2142 * blk_cloned_rq_check_limits - Helper function to check a cloned request
2143 * for new the queue limits
2145 * @rq: the request being checked
2148 * @rq may have been made based on weaker limitations of upper-level queues
2149 * in request stacking drivers, and it may violate the limitation of @q.
2150 * Since the block layer and the underlying device driver trust @rq
2151 * after it is inserted to @q, it should be checked against @q before
2152 * the insertion using this generic function.
2154 * Request stacking drivers like request-based dm may change the queue
2155 * limits when retrying requests on other queues. Those requests need
2156 * to be checked against the new queue limits again during dispatch.
2158 static int blk_cloned_rq_check_limits(struct request_queue
*q
,
2161 if (blk_rq_sectors(rq
) > blk_queue_get_max_sectors(q
, rq
->cmd_flags
)) {
2162 printk(KERN_ERR
"%s: over max size limit.\n", __func__
);
2167 * queue's settings related to segment counting like q->bounce_pfn
2168 * may differ from that of other stacking queues.
2169 * Recalculate it to check the request correctly on this queue's
2172 blk_recalc_rq_segments(rq
);
2173 if (rq
->nr_phys_segments
> queue_max_segments(q
)) {
2174 printk(KERN_ERR
"%s: over max segments limit.\n", __func__
);
2182 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
2183 * @q: the queue to submit the request
2184 * @rq: the request being queued
2186 int blk_insert_cloned_request(struct request_queue
*q
, struct request
*rq
)
2188 unsigned long flags
;
2189 int where
= ELEVATOR_INSERT_BACK
;
2191 if (blk_cloned_rq_check_limits(q
, rq
))
2195 should_fail_request(&rq
->rq_disk
->part0
, blk_rq_bytes(rq
)))
2199 if (blk_queue_io_stat(q
))
2200 blk_account_io_start(rq
, true);
2201 blk_mq_insert_request(rq
, false, true, true);
2205 spin_lock_irqsave(q
->queue_lock
, flags
);
2206 if (unlikely(blk_queue_dying(q
))) {
2207 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2212 * Submitting request must be dequeued before calling this function
2213 * because it will be linked to another request_queue
2215 BUG_ON(blk_queued_rq(rq
));
2217 if (rq
->cmd_flags
& (REQ_FLUSH
|REQ_FUA
))
2218 where
= ELEVATOR_INSERT_FLUSH
;
2220 add_acct_request(q
, rq
, where
);
2221 if (where
== ELEVATOR_INSERT_FLUSH
)
2223 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2227 EXPORT_SYMBOL_GPL(blk_insert_cloned_request
);
2230 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
2231 * @rq: request to examine
2234 * A request could be merge of IOs which require different failure
2235 * handling. This function determines the number of bytes which
2236 * can be failed from the beginning of the request without
2237 * crossing into area which need to be retried further.
2240 * The number of bytes to fail.
2243 * queue_lock must be held.
2245 unsigned int blk_rq_err_bytes(const struct request
*rq
)
2247 unsigned int ff
= rq
->cmd_flags
& REQ_FAILFAST_MASK
;
2248 unsigned int bytes
= 0;
2251 if (!(rq
->cmd_flags
& REQ_MIXED_MERGE
))
2252 return blk_rq_bytes(rq
);
2255 * Currently the only 'mixing' which can happen is between
2256 * different fastfail types. We can safely fail portions
2257 * which have all the failfast bits that the first one has -
2258 * the ones which are at least as eager to fail as the first
2261 for (bio
= rq
->bio
; bio
; bio
= bio
->bi_next
) {
2262 if ((bio
->bi_rw
& ff
) != ff
)
2264 bytes
+= bio
->bi_iter
.bi_size
;
2267 /* this could lead to infinite loop */
2268 BUG_ON(blk_rq_bytes(rq
) && !bytes
);
2271 EXPORT_SYMBOL_GPL(blk_rq_err_bytes
);
2273 void blk_account_io_completion(struct request
*req
, unsigned int bytes
)
2275 if (blk_do_io_stat(req
)) {
2276 const int rw
= rq_data_dir(req
);
2277 struct hd_struct
*part
;
2280 cpu
= part_stat_lock();
2282 part_stat_add(cpu
, part
, sectors
[rw
], bytes
>> 9);
2287 void blk_account_io_done(struct request
*req
)
2290 * Account IO completion. flush_rq isn't accounted as a
2291 * normal IO on queueing nor completion. Accounting the
2292 * containing request is enough.
2294 if (blk_do_io_stat(req
) && !(req
->cmd_flags
& REQ_FLUSH_SEQ
)) {
2295 unsigned long duration
= jiffies
- req
->start_time
;
2296 const int rw
= rq_data_dir(req
);
2297 struct hd_struct
*part
;
2300 cpu
= part_stat_lock();
2303 part_stat_inc(cpu
, part
, ios
[rw
]);
2304 part_stat_add(cpu
, part
, ticks
[rw
], duration
);
2305 part_round_stats(cpu
, part
);
2306 part_dec_in_flight(part
, rw
);
2308 hd_struct_put(part
);
2315 * Don't process normal requests when queue is suspended
2316 * or in the process of suspending/resuming
2318 static struct request
*blk_pm_peek_request(struct request_queue
*q
,
2321 if (q
->dev
&& (q
->rpm_status
== RPM_SUSPENDED
||
2322 (q
->rpm_status
!= RPM_ACTIVE
&& !(rq
->cmd_flags
& REQ_PM
))))
2328 static inline struct request
*blk_pm_peek_request(struct request_queue
*q
,
2335 void blk_account_io_start(struct request
*rq
, bool new_io
)
2337 struct hd_struct
*part
;
2338 int rw
= rq_data_dir(rq
);
2341 if (!blk_do_io_stat(rq
))
2344 cpu
= part_stat_lock();
2348 part_stat_inc(cpu
, part
, merges
[rw
]);
2350 part
= disk_map_sector_rcu(rq
->rq_disk
, blk_rq_pos(rq
));
2351 if (!hd_struct_try_get(part
)) {
2353 * The partition is already being removed,
2354 * the request will be accounted on the disk only
2356 * We take a reference on disk->part0 although that
2357 * partition will never be deleted, so we can treat
2358 * it as any other partition.
2360 part
= &rq
->rq_disk
->part0
;
2361 hd_struct_get(part
);
2363 part_round_stats(cpu
, part
);
2364 part_inc_in_flight(part
, rw
);
2372 * blk_peek_request - peek at the top of a request queue
2373 * @q: request queue to peek at
2376 * Return the request at the top of @q. The returned request
2377 * should be started using blk_start_request() before LLD starts
2381 * Pointer to the request at the top of @q if available. Null
2385 * queue_lock must be held.
2387 struct request
*blk_peek_request(struct request_queue
*q
)
2392 while ((rq
= __elv_next_request(q
)) != NULL
) {
2394 rq
= blk_pm_peek_request(q
, rq
);
2398 if (!(rq
->cmd_flags
& REQ_STARTED
)) {
2400 * This is the first time the device driver
2401 * sees this request (possibly after
2402 * requeueing). Notify IO scheduler.
2404 if (rq
->cmd_flags
& REQ_SORTED
)
2405 elv_activate_rq(q
, rq
);
2408 * just mark as started even if we don't start
2409 * it, a request that has been delayed should
2410 * not be passed by new incoming requests
2412 rq
->cmd_flags
|= REQ_STARTED
;
2413 trace_block_rq_issue(q
, rq
);
2416 if (!q
->boundary_rq
|| q
->boundary_rq
== rq
) {
2417 q
->end_sector
= rq_end_sector(rq
);
2418 q
->boundary_rq
= NULL
;
2421 if (rq
->cmd_flags
& REQ_DONTPREP
)
2424 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
2426 * make sure space for the drain appears we
2427 * know we can do this because max_hw_segments
2428 * has been adjusted to be one fewer than the
2431 rq
->nr_phys_segments
++;
2437 ret
= q
->prep_rq_fn(q
, rq
);
2438 if (ret
== BLKPREP_OK
) {
2440 } else if (ret
== BLKPREP_DEFER
) {
2442 * the request may have been (partially) prepped.
2443 * we need to keep this request in the front to
2444 * avoid resource deadlock. REQ_STARTED will
2445 * prevent other fs requests from passing this one.
2447 if (q
->dma_drain_size
&& blk_rq_bytes(rq
) &&
2448 !(rq
->cmd_flags
& REQ_DONTPREP
)) {
2450 * remove the space for the drain we added
2451 * so that we don't add it again
2453 --rq
->nr_phys_segments
;
2458 } else if (ret
== BLKPREP_KILL
) {
2459 rq
->cmd_flags
|= REQ_QUIET
;
2461 * Mark this request as started so we don't trigger
2462 * any debug logic in the end I/O path.
2464 blk_start_request(rq
);
2465 __blk_end_request_all(rq
, -EIO
);
2467 printk(KERN_ERR
"%s: bad return=%d\n", __func__
, ret
);
2474 EXPORT_SYMBOL(blk_peek_request
);
2476 void blk_dequeue_request(struct request
*rq
)
2478 struct request_queue
*q
= rq
->q
;
2480 BUG_ON(list_empty(&rq
->queuelist
));
2481 BUG_ON(ELV_ON_HASH(rq
));
2483 list_del_init(&rq
->queuelist
);
2486 * the time frame between a request being removed from the lists
2487 * and to it is freed is accounted as io that is in progress at
2490 if (blk_account_rq(rq
)) {
2491 q
->in_flight
[rq_is_sync(rq
)]++;
2492 set_io_start_time_ns(rq
);
2497 * blk_start_request - start request processing on the driver
2498 * @req: request to dequeue
2501 * Dequeue @req and start timeout timer on it. This hands off the
2502 * request to the driver.
2504 * Block internal functions which don't want to start timer should
2505 * call blk_dequeue_request().
2508 * queue_lock must be held.
2510 void blk_start_request(struct request
*req
)
2512 blk_dequeue_request(req
);
2515 * We are now handing the request to the hardware, initialize
2516 * resid_len to full count and add the timeout handler.
2518 req
->resid_len
= blk_rq_bytes(req
);
2519 if (unlikely(blk_bidi_rq(req
)))
2520 req
->next_rq
->resid_len
= blk_rq_bytes(req
->next_rq
);
2522 BUG_ON(test_bit(REQ_ATOM_COMPLETE
, &req
->atomic_flags
));
2525 EXPORT_SYMBOL(blk_start_request
);
2528 * blk_fetch_request - fetch a request from a request queue
2529 * @q: request queue to fetch a request from
2532 * Return the request at the top of @q. The request is started on
2533 * return and LLD can start processing it immediately.
2536 * Pointer to the request at the top of @q if available. Null
2540 * queue_lock must be held.
2542 struct request
*blk_fetch_request(struct request_queue
*q
)
2546 rq
= blk_peek_request(q
);
2548 blk_start_request(rq
);
2551 EXPORT_SYMBOL(blk_fetch_request
);
2554 * blk_update_request - Special helper function for request stacking drivers
2555 * @req: the request being processed
2556 * @error: %0 for success, < %0 for error
2557 * @nr_bytes: number of bytes to complete @req
2560 * Ends I/O on a number of bytes attached to @req, but doesn't complete
2561 * the request structure even if @req doesn't have leftover.
2562 * If @req has leftover, sets it up for the next range of segments.
2564 * This special helper function is only for request stacking drivers
2565 * (e.g. request-based dm) so that they can handle partial completion.
2566 * Actual device drivers should use blk_end_request instead.
2568 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
2569 * %false return from this function.
2572 * %false - this request doesn't have any more data
2573 * %true - this request has more data
2575 bool blk_update_request(struct request
*req
, int error
, unsigned int nr_bytes
)
2579 trace_block_rq_complete(req
->q
, req
, nr_bytes
);
2585 * For fs requests, rq is just carrier of independent bio's
2586 * and each partial completion should be handled separately.
2587 * Reset per-request error on each partial completion.
2589 * TODO: tj: This is too subtle. It would be better to let
2590 * low level drivers do what they see fit.
2592 if (req
->cmd_type
== REQ_TYPE_FS
)
2595 if (error
&& req
->cmd_type
== REQ_TYPE_FS
&&
2596 !(req
->cmd_flags
& REQ_QUIET
)) {
2601 error_type
= "recoverable transport";
2604 error_type
= "critical target";
2607 error_type
= "critical nexus";
2610 error_type
= "timeout";
2613 error_type
= "critical space allocation";
2616 error_type
= "critical medium";
2623 printk_ratelimited(KERN_ERR
"%s: %s error, dev %s, sector %llu\n",
2624 __func__
, error_type
, req
->rq_disk
?
2625 req
->rq_disk
->disk_name
: "?",
2626 (unsigned long long)blk_rq_pos(req
));
2630 blk_account_io_completion(req
, nr_bytes
);
2634 struct bio
*bio
= req
->bio
;
2635 unsigned bio_bytes
= min(bio
->bi_iter
.bi_size
, nr_bytes
);
2637 if (bio_bytes
== bio
->bi_iter
.bi_size
)
2638 req
->bio
= bio
->bi_next
;
2640 req_bio_endio(req
, bio
, bio_bytes
, error
);
2642 total_bytes
+= bio_bytes
;
2643 nr_bytes
-= bio_bytes
;
2654 * Reset counters so that the request stacking driver
2655 * can find how many bytes remain in the request
2658 req
->__data_len
= 0;
2662 req
->__data_len
-= total_bytes
;
2664 /* update sector only for requests with clear definition of sector */
2665 if (req
->cmd_type
== REQ_TYPE_FS
)
2666 req
->__sector
+= total_bytes
>> 9;
2668 /* mixed attributes always follow the first bio */
2669 if (req
->cmd_flags
& REQ_MIXED_MERGE
) {
2670 req
->cmd_flags
&= ~REQ_FAILFAST_MASK
;
2671 req
->cmd_flags
|= req
->bio
->bi_rw
& REQ_FAILFAST_MASK
;
2675 * If total number of sectors is less than the first segment
2676 * size, something has gone terribly wrong.
2678 if (blk_rq_bytes(req
) < blk_rq_cur_bytes(req
)) {
2679 blk_dump_rq_flags(req
, "request botched");
2680 req
->__data_len
= blk_rq_cur_bytes(req
);
2683 /* recalculate the number of segments */
2684 blk_recalc_rq_segments(req
);
2688 EXPORT_SYMBOL_GPL(blk_update_request
);
2690 static bool blk_update_bidi_request(struct request
*rq
, int error
,
2691 unsigned int nr_bytes
,
2692 unsigned int bidi_bytes
)
2694 if (blk_update_request(rq
, error
, nr_bytes
))
2697 /* Bidi request must be completed as a whole */
2698 if (unlikely(blk_bidi_rq(rq
)) &&
2699 blk_update_request(rq
->next_rq
, error
, bidi_bytes
))
2702 if (blk_queue_add_random(rq
->q
))
2703 add_disk_randomness(rq
->rq_disk
);
2709 * blk_unprep_request - unprepare a request
2712 * This function makes a request ready for complete resubmission (or
2713 * completion). It happens only after all error handling is complete,
2714 * so represents the appropriate moment to deallocate any resources
2715 * that were allocated to the request in the prep_rq_fn. The queue
2716 * lock is held when calling this.
2718 void blk_unprep_request(struct request
*req
)
2720 struct request_queue
*q
= req
->q
;
2722 req
->cmd_flags
&= ~REQ_DONTPREP
;
2723 if (q
->unprep_rq_fn
)
2724 q
->unprep_rq_fn(q
, req
);
2726 EXPORT_SYMBOL_GPL(blk_unprep_request
);
2729 * queue lock must be held
2731 void blk_finish_request(struct request
*req
, int error
)
2733 if (req
->cmd_flags
& REQ_QUEUED
)
2734 blk_queue_end_tag(req
->q
, req
);
2736 BUG_ON(blk_queued_rq(req
));
2738 if (unlikely(laptop_mode
) && req
->cmd_type
== REQ_TYPE_FS
)
2739 laptop_io_completion(&req
->q
->backing_dev_info
);
2741 blk_delete_timer(req
);
2743 if (req
->cmd_flags
& REQ_DONTPREP
)
2744 blk_unprep_request(req
);
2746 blk_account_io_done(req
);
2749 req
->end_io(req
, error
);
2751 if (blk_bidi_rq(req
))
2752 __blk_put_request(req
->next_rq
->q
, req
->next_rq
);
2754 __blk_put_request(req
->q
, req
);
2757 EXPORT_SYMBOL(blk_finish_request
);
2760 * blk_end_bidi_request - Complete a bidi request
2761 * @rq: the request to complete
2762 * @error: %0 for success, < %0 for error
2763 * @nr_bytes: number of bytes to complete @rq
2764 * @bidi_bytes: number of bytes to complete @rq->next_rq
2767 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2768 * Drivers that supports bidi can safely call this member for any
2769 * type of request, bidi or uni. In the later case @bidi_bytes is
2773 * %false - we are done with this request
2774 * %true - still buffers pending for this request
2776 static bool blk_end_bidi_request(struct request
*rq
, int error
,
2777 unsigned int nr_bytes
, unsigned int bidi_bytes
)
2779 struct request_queue
*q
= rq
->q
;
2780 unsigned long flags
;
2782 if (blk_update_bidi_request(rq
, error
, nr_bytes
, bidi_bytes
))
2785 spin_lock_irqsave(q
->queue_lock
, flags
);
2786 blk_finish_request(rq
, error
);
2787 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2793 * __blk_end_bidi_request - Complete a bidi request with queue lock held
2794 * @rq: the request to complete
2795 * @error: %0 for success, < %0 for error
2796 * @nr_bytes: number of bytes to complete @rq
2797 * @bidi_bytes: number of bytes to complete @rq->next_rq
2800 * Identical to blk_end_bidi_request() except that queue lock is
2801 * assumed to be locked on entry and remains so on return.
2804 * %false - we are done with this request
2805 * %true - still buffers pending for this request
2807 bool __blk_end_bidi_request(struct request
*rq
, int error
,
2808 unsigned int nr_bytes
, unsigned int bidi_bytes
)
2810 if (blk_update_bidi_request(rq
, error
, nr_bytes
, bidi_bytes
))
2813 blk_finish_request(rq
, error
);
2819 * blk_end_request - Helper function for drivers to complete the request.
2820 * @rq: the request being processed
2821 * @error: %0 for success, < %0 for error
2822 * @nr_bytes: number of bytes to complete
2825 * Ends I/O on a number of bytes attached to @rq.
2826 * If @rq has leftover, sets it up for the next range of segments.
2829 * %false - we are done with this request
2830 * %true - still buffers pending for this request
2832 bool blk_end_request(struct request
*rq
, int error
, unsigned int nr_bytes
)
2834 return blk_end_bidi_request(rq
, error
, nr_bytes
, 0);
2836 EXPORT_SYMBOL(blk_end_request
);
2839 * blk_end_request_all - Helper function for drives to finish the request.
2840 * @rq: the request to finish
2841 * @error: %0 for success, < %0 for error
2844 * Completely finish @rq.
2846 void blk_end_request_all(struct request
*rq
, int error
)
2849 unsigned int bidi_bytes
= 0;
2851 if (unlikely(blk_bidi_rq(rq
)))
2852 bidi_bytes
= blk_rq_bytes(rq
->next_rq
);
2854 pending
= blk_end_bidi_request(rq
, error
, blk_rq_bytes(rq
), bidi_bytes
);
2857 EXPORT_SYMBOL(blk_end_request_all
);
2860 * blk_end_request_cur - Helper function to finish the current request chunk.
2861 * @rq: the request to finish the current chunk for
2862 * @error: %0 for success, < %0 for error
2865 * Complete the current consecutively mapped chunk from @rq.
2868 * %false - we are done with this request
2869 * %true - still buffers pending for this request
2871 bool blk_end_request_cur(struct request
*rq
, int error
)
2873 return blk_end_request(rq
, error
, blk_rq_cur_bytes(rq
));
2875 EXPORT_SYMBOL(blk_end_request_cur
);
2878 * blk_end_request_err - Finish a request till the next failure boundary.
2879 * @rq: the request to finish till the next failure boundary for
2880 * @error: must be negative errno
2883 * Complete @rq till the next failure boundary.
2886 * %false - we are done with this request
2887 * %true - still buffers pending for this request
2889 bool blk_end_request_err(struct request
*rq
, int error
)
2891 WARN_ON(error
>= 0);
2892 return blk_end_request(rq
, error
, blk_rq_err_bytes(rq
));
2894 EXPORT_SYMBOL_GPL(blk_end_request_err
);
2897 * __blk_end_request - Helper function for drivers to complete the request.
2898 * @rq: the request being processed
2899 * @error: %0 for success, < %0 for error
2900 * @nr_bytes: number of bytes to complete
2903 * Must be called with queue lock held unlike blk_end_request().
2906 * %false - we are done with this request
2907 * %true - still buffers pending for this request
2909 bool __blk_end_request(struct request
*rq
, int error
, unsigned int nr_bytes
)
2911 return __blk_end_bidi_request(rq
, error
, nr_bytes
, 0);
2913 EXPORT_SYMBOL(__blk_end_request
);
2916 * __blk_end_request_all - Helper function for drives to finish the request.
2917 * @rq: the request to finish
2918 * @error: %0 for success, < %0 for error
2921 * Completely finish @rq. Must be called with queue lock held.
2923 void __blk_end_request_all(struct request
*rq
, int error
)
2926 unsigned int bidi_bytes
= 0;
2928 if (unlikely(blk_bidi_rq(rq
)))
2929 bidi_bytes
= blk_rq_bytes(rq
->next_rq
);
2931 pending
= __blk_end_bidi_request(rq
, error
, blk_rq_bytes(rq
), bidi_bytes
);
2934 EXPORT_SYMBOL(__blk_end_request_all
);
2937 * __blk_end_request_cur - Helper function to finish the current request chunk.
2938 * @rq: the request to finish the current chunk for
2939 * @error: %0 for success, < %0 for error
2942 * Complete the current consecutively mapped chunk from @rq. Must
2943 * be called with queue lock held.
2946 * %false - we are done with this request
2947 * %true - still buffers pending for this request
2949 bool __blk_end_request_cur(struct request
*rq
, int error
)
2951 return __blk_end_request(rq
, error
, blk_rq_cur_bytes(rq
));
2953 EXPORT_SYMBOL(__blk_end_request_cur
);
2956 * __blk_end_request_err - Finish a request till the next failure boundary.
2957 * @rq: the request to finish till the next failure boundary for
2958 * @error: must be negative errno
2961 * Complete @rq till the next failure boundary. Must be called
2962 * with queue lock held.
2965 * %false - we are done with this request
2966 * %true - still buffers pending for this request
2968 bool __blk_end_request_err(struct request
*rq
, int error
)
2970 WARN_ON(error
>= 0);
2971 return __blk_end_request(rq
, error
, blk_rq_err_bytes(rq
));
2973 EXPORT_SYMBOL_GPL(__blk_end_request_err
);
2975 void blk_rq_bio_prep(struct request_queue
*q
, struct request
*rq
,
2978 /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */
2979 rq
->cmd_flags
|= bio
->bi_rw
& REQ_WRITE
;
2981 if (bio_has_data(bio
))
2982 rq
->nr_phys_segments
= bio_phys_segments(q
, bio
);
2984 rq
->__data_len
= bio
->bi_iter
.bi_size
;
2985 rq
->bio
= rq
->biotail
= bio
;
2988 rq
->rq_disk
= bio
->bi_bdev
->bd_disk
;
2991 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
2993 * rq_flush_dcache_pages - Helper function to flush all pages in a request
2994 * @rq: the request to be flushed
2997 * Flush all pages in @rq.
2999 void rq_flush_dcache_pages(struct request
*rq
)
3001 struct req_iterator iter
;
3002 struct bio_vec bvec
;
3004 rq_for_each_segment(bvec
, rq
, iter
)
3005 flush_dcache_page(bvec
.bv_page
);
3007 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages
);
3011 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
3012 * @q : the queue of the device being checked
3015 * Check if underlying low-level drivers of a device are busy.
3016 * If the drivers want to export their busy state, they must set own
3017 * exporting function using blk_queue_lld_busy() first.
3019 * Basically, this function is used only by request stacking drivers
3020 * to stop dispatching requests to underlying devices when underlying
3021 * devices are busy. This behavior helps more I/O merging on the queue
3022 * of the request stacking driver and prevents I/O throughput regression
3023 * on burst I/O load.
3026 * 0 - Not busy (The request stacking driver should dispatch request)
3027 * 1 - Busy (The request stacking driver should stop dispatching request)
3029 int blk_lld_busy(struct request_queue
*q
)
3032 return q
->lld_busy_fn(q
);
3036 EXPORT_SYMBOL_GPL(blk_lld_busy
);
3039 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
3040 * @rq: the clone request to be cleaned up
3043 * Free all bios in @rq for a cloned request.
3045 void blk_rq_unprep_clone(struct request
*rq
)
3049 while ((bio
= rq
->bio
) != NULL
) {
3050 rq
->bio
= bio
->bi_next
;
3055 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone
);
3058 * Copy attributes of the original request to the clone request.
3059 * The actual data parts (e.g. ->cmd, ->sense) are not copied.
3061 static void __blk_rq_prep_clone(struct request
*dst
, struct request
*src
)
3063 dst
->cpu
= src
->cpu
;
3064 dst
->cmd_flags
|= (src
->cmd_flags
& REQ_CLONE_MASK
) | REQ_NOMERGE
;
3065 dst
->cmd_type
= src
->cmd_type
;
3066 dst
->__sector
= blk_rq_pos(src
);
3067 dst
->__data_len
= blk_rq_bytes(src
);
3068 dst
->nr_phys_segments
= src
->nr_phys_segments
;
3069 dst
->ioprio
= src
->ioprio
;
3070 dst
->extra_len
= src
->extra_len
;
3074 * blk_rq_prep_clone - Helper function to setup clone request
3075 * @rq: the request to be setup
3076 * @rq_src: original request to be cloned
3077 * @bs: bio_set that bios for clone are allocated from
3078 * @gfp_mask: memory allocation mask for bio
3079 * @bio_ctr: setup function to be called for each clone bio.
3080 * Returns %0 for success, non %0 for failure.
3081 * @data: private data to be passed to @bio_ctr
3084 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
3085 * The actual data parts of @rq_src (e.g. ->cmd, ->sense)
3086 * are not copied, and copying such parts is the caller's responsibility.
3087 * Also, pages which the original bios are pointing to are not copied
3088 * and the cloned bios just point same pages.
3089 * So cloned bios must be completed before original bios, which means
3090 * the caller must complete @rq before @rq_src.
3092 int blk_rq_prep_clone(struct request
*rq
, struct request
*rq_src
,
3093 struct bio_set
*bs
, gfp_t gfp_mask
,
3094 int (*bio_ctr
)(struct bio
*, struct bio
*, void *),
3097 struct bio
*bio
, *bio_src
;
3102 __rq_for_each_bio(bio_src
, rq_src
) {
3103 bio
= bio_clone_fast(bio_src
, gfp_mask
, bs
);
3107 if (bio_ctr
&& bio_ctr(bio
, bio_src
, data
))
3111 rq
->biotail
->bi_next
= bio
;
3114 rq
->bio
= rq
->biotail
= bio
;
3117 __blk_rq_prep_clone(rq
, rq_src
);
3124 blk_rq_unprep_clone(rq
);
3128 EXPORT_SYMBOL_GPL(blk_rq_prep_clone
);
3130 int kblockd_schedule_work(struct work_struct
*work
)
3132 return queue_work(kblockd_workqueue
, work
);
3134 EXPORT_SYMBOL(kblockd_schedule_work
);
3136 int kblockd_schedule_delayed_work(struct delayed_work
*dwork
,
3137 unsigned long delay
)
3139 return queue_delayed_work(kblockd_workqueue
, dwork
, delay
);
3141 EXPORT_SYMBOL(kblockd_schedule_delayed_work
);
3143 int kblockd_schedule_delayed_work_on(int cpu
, struct delayed_work
*dwork
,
3144 unsigned long delay
)
3146 return queue_delayed_work_on(cpu
, kblockd_workqueue
, dwork
, delay
);
3148 EXPORT_SYMBOL(kblockd_schedule_delayed_work_on
);
3151 * blk_start_plug - initialize blk_plug and track it inside the task_struct
3152 * @plug: The &struct blk_plug that needs to be initialized
3155 * Tracking blk_plug inside the task_struct will help with auto-flushing the
3156 * pending I/O should the task end up blocking between blk_start_plug() and
3157 * blk_finish_plug(). This is important from a performance perspective, but
3158 * also ensures that we don't deadlock. For instance, if the task is blocking
3159 * for a memory allocation, memory reclaim could end up wanting to free a
3160 * page belonging to that request that is currently residing in our private
3161 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
3162 * this kind of deadlock.
3164 void blk_start_plug(struct blk_plug
*plug
)
3166 struct task_struct
*tsk
= current
;
3169 * If this is a nested plug, don't actually assign it.
3174 INIT_LIST_HEAD(&plug
->list
);
3175 INIT_LIST_HEAD(&plug
->mq_list
);
3176 INIT_LIST_HEAD(&plug
->cb_list
);
3178 * Store ordering should not be needed here, since a potential
3179 * preempt will imply a full memory barrier
3183 EXPORT_SYMBOL(blk_start_plug
);
3185 static int plug_rq_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
3187 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
3188 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
3190 return !(rqa
->q
< rqb
->q
||
3191 (rqa
->q
== rqb
->q
&& blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
3195 * If 'from_schedule' is true, then postpone the dispatch of requests
3196 * until a safe kblockd context. We due this to avoid accidental big
3197 * additional stack usage in driver dispatch, in places where the originally
3198 * plugger did not intend it.
3200 static void queue_unplugged(struct request_queue
*q
, unsigned int depth
,
3202 __releases(q
->queue_lock
)
3204 trace_block_unplug(q
, depth
, !from_schedule
);
3207 blk_run_queue_async(q
);
3210 spin_unlock(q
->queue_lock
);
3213 static void flush_plug_callbacks(struct blk_plug
*plug
, bool from_schedule
)
3215 LIST_HEAD(callbacks
);
3217 while (!list_empty(&plug
->cb_list
)) {
3218 list_splice_init(&plug
->cb_list
, &callbacks
);
3220 while (!list_empty(&callbacks
)) {
3221 struct blk_plug_cb
*cb
= list_first_entry(&callbacks
,
3224 list_del(&cb
->list
);
3225 cb
->callback(cb
, from_schedule
);
3230 struct blk_plug_cb
*blk_check_plugged(blk_plug_cb_fn unplug
, void *data
,
3233 struct blk_plug
*plug
= current
->plug
;
3234 struct blk_plug_cb
*cb
;
3239 list_for_each_entry(cb
, &plug
->cb_list
, list
)
3240 if (cb
->callback
== unplug
&& cb
->data
== data
)
3243 /* Not currently on the callback list */
3244 BUG_ON(size
< sizeof(*cb
));
3245 cb
= kzalloc(size
, GFP_ATOMIC
);
3248 cb
->callback
= unplug
;
3249 list_add(&cb
->list
, &plug
->cb_list
);
3253 EXPORT_SYMBOL(blk_check_plugged
);
3255 void blk_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
3257 struct request_queue
*q
;
3258 unsigned long flags
;
3263 flush_plug_callbacks(plug
, from_schedule
);
3265 if (!list_empty(&plug
->mq_list
))
3266 blk_mq_flush_plug_list(plug
, from_schedule
);
3268 if (list_empty(&plug
->list
))
3271 list_splice_init(&plug
->list
, &list
);
3273 list_sort(NULL
, &list
, plug_rq_cmp
);
3279 * Save and disable interrupts here, to avoid doing it for every
3280 * queue lock we have to take.
3282 local_irq_save(flags
);
3283 while (!list_empty(&list
)) {
3284 rq
= list_entry_rq(list
.next
);
3285 list_del_init(&rq
->queuelist
);
3289 * This drops the queue lock
3292 queue_unplugged(q
, depth
, from_schedule
);
3295 spin_lock(q
->queue_lock
);
3299 * Short-circuit if @q is dead
3301 if (unlikely(blk_queue_dying(q
))) {
3302 __blk_end_request_all(rq
, -ENODEV
);
3307 * rq is already accounted, so use raw insert
3309 if (rq
->cmd_flags
& (REQ_FLUSH
| REQ_FUA
))
3310 __elv_add_request(q
, rq
, ELEVATOR_INSERT_FLUSH
);
3312 __elv_add_request(q
, rq
, ELEVATOR_INSERT_SORT_MERGE
);
3318 * This drops the queue lock
3321 queue_unplugged(q
, depth
, from_schedule
);
3323 local_irq_restore(flags
);
3326 void blk_finish_plug(struct blk_plug
*plug
)
3328 if (plug
!= current
->plug
)
3330 blk_flush_plug_list(plug
, false);
3332 current
->plug
= NULL
;
3334 EXPORT_SYMBOL(blk_finish_plug
);
3336 bool blk_poll(struct request_queue
*q
, blk_qc_t cookie
)
3338 struct blk_plug
*plug
;
3341 if (!q
->mq_ops
|| !q
->mq_ops
->poll
|| !blk_qc_t_valid(cookie
) ||
3342 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
3345 plug
= current
->plug
;
3347 blk_flush_plug_list(plug
, false);
3349 state
= current
->state
;
3350 while (!need_resched()) {
3351 unsigned int queue_num
= blk_qc_t_to_queue_num(cookie
);
3352 struct blk_mq_hw_ctx
*hctx
= q
->queue_hw_ctx
[queue_num
];
3355 hctx
->poll_invoked
++;
3357 ret
= q
->mq_ops
->poll(hctx
, blk_qc_t_to_tag(cookie
));
3359 hctx
->poll_success
++;
3360 set_current_state(TASK_RUNNING
);
3364 if (signal_pending_state(state
, current
))
3365 set_current_state(TASK_RUNNING
);
3367 if (current
->state
== TASK_RUNNING
)
3379 * blk_pm_runtime_init - Block layer runtime PM initialization routine
3380 * @q: the queue of the device
3381 * @dev: the device the queue belongs to
3384 * Initialize runtime-PM-related fields for @q and start auto suspend for
3385 * @dev. Drivers that want to take advantage of request-based runtime PM
3386 * should call this function after @dev has been initialized, and its
3387 * request queue @q has been allocated, and runtime PM for it can not happen
3388 * yet(either due to disabled/forbidden or its usage_count > 0). In most
3389 * cases, driver should call this function before any I/O has taken place.
3391 * This function takes care of setting up using auto suspend for the device,
3392 * the autosuspend delay is set to -1 to make runtime suspend impossible
3393 * until an updated value is either set by user or by driver. Drivers do
3394 * not need to touch other autosuspend settings.
3396 * The block layer runtime PM is request based, so only works for drivers
3397 * that use request as their IO unit instead of those directly use bio's.
3399 void blk_pm_runtime_init(struct request_queue
*q
, struct device
*dev
)
3402 q
->rpm_status
= RPM_ACTIVE
;
3403 pm_runtime_set_autosuspend_delay(q
->dev
, -1);
3404 pm_runtime_use_autosuspend(q
->dev
);
3406 EXPORT_SYMBOL(blk_pm_runtime_init
);
3409 * blk_pre_runtime_suspend - Pre runtime suspend check
3410 * @q: the queue of the device
3413 * This function will check if runtime suspend is allowed for the device
3414 * by examining if there are any requests pending in the queue. If there
3415 * are requests pending, the device can not be runtime suspended; otherwise,
3416 * the queue's status will be updated to SUSPENDING and the driver can
3417 * proceed to suspend the device.
3419 * For the not allowed case, we mark last busy for the device so that
3420 * runtime PM core will try to autosuspend it some time later.
3422 * This function should be called near the start of the device's
3423 * runtime_suspend callback.
3426 * 0 - OK to runtime suspend the device
3427 * -EBUSY - Device should not be runtime suspended
3429 int blk_pre_runtime_suspend(struct request_queue
*q
)
3436 spin_lock_irq(q
->queue_lock
);
3437 if (q
->nr_pending
) {
3439 pm_runtime_mark_last_busy(q
->dev
);
3441 q
->rpm_status
= RPM_SUSPENDING
;
3443 spin_unlock_irq(q
->queue_lock
);
3446 EXPORT_SYMBOL(blk_pre_runtime_suspend
);
3449 * blk_post_runtime_suspend - Post runtime suspend processing
3450 * @q: the queue of the device
3451 * @err: return value of the device's runtime_suspend function
3454 * Update the queue's runtime status according to the return value of the
3455 * device's runtime suspend function and mark last busy for the device so
3456 * that PM core will try to auto suspend the device at a later time.
3458 * This function should be called near the end of the device's
3459 * runtime_suspend callback.
3461 void blk_post_runtime_suspend(struct request_queue
*q
, int err
)
3466 spin_lock_irq(q
->queue_lock
);
3468 q
->rpm_status
= RPM_SUSPENDED
;
3470 q
->rpm_status
= RPM_ACTIVE
;
3471 pm_runtime_mark_last_busy(q
->dev
);
3473 spin_unlock_irq(q
->queue_lock
);
3475 EXPORT_SYMBOL(blk_post_runtime_suspend
);
3478 * blk_pre_runtime_resume - Pre runtime resume processing
3479 * @q: the queue of the device
3482 * Update the queue's runtime status to RESUMING in preparation for the
3483 * runtime resume of the device.
3485 * This function should be called near the start of the device's
3486 * runtime_resume callback.
3488 void blk_pre_runtime_resume(struct request_queue
*q
)
3493 spin_lock_irq(q
->queue_lock
);
3494 q
->rpm_status
= RPM_RESUMING
;
3495 spin_unlock_irq(q
->queue_lock
);
3497 EXPORT_SYMBOL(blk_pre_runtime_resume
);
3500 * blk_post_runtime_resume - Post runtime resume processing
3501 * @q: the queue of the device
3502 * @err: return value of the device's runtime_resume function
3505 * Update the queue's runtime status according to the return value of the
3506 * device's runtime_resume function. If it is successfully resumed, process
3507 * the requests that are queued into the device's queue when it is resuming
3508 * and then mark last busy and initiate autosuspend for it.
3510 * This function should be called near the end of the device's
3511 * runtime_resume callback.
3513 void blk_post_runtime_resume(struct request_queue
*q
, int err
)
3518 spin_lock_irq(q
->queue_lock
);
3520 q
->rpm_status
= RPM_ACTIVE
;
3522 pm_runtime_mark_last_busy(q
->dev
);
3523 pm_request_autosuspend(q
->dev
);
3525 q
->rpm_status
= RPM_SUSPENDED
;
3527 spin_unlock_irq(q
->queue_lock
);
3529 EXPORT_SYMBOL(blk_post_runtime_resume
);
3532 int __init
blk_dev_init(void)
3534 BUILD_BUG_ON(__REQ_NR_BITS
> 8 *
3535 FIELD_SIZEOF(struct request
, cmd_flags
));
3537 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
3538 kblockd_workqueue
= alloc_workqueue("kblockd",
3539 WQ_MEM_RECLAIM
| WQ_HIGHPRI
, 0);
3540 if (!kblockd_workqueue
)
3541 panic("Failed to create kblockd\n");
3543 request_cachep
= kmem_cache_create("blkdev_requests",
3544 sizeof(struct request
), 0, SLAB_PANIC
, NULL
);
3546 blk_requestq_cachep
= kmem_cache_create("request_queue",
3547 sizeof(struct request_queue
), 0, SLAB_PANIC
, NULL
);