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
= NULL
;
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 - restart a previously stopped queue
211 * @q: The &struct request_queue in question
214 * blk_start_queue() will clear the stop flag on the queue, and call
215 * the request_fn for the queue if it was in a stopped state when
216 * entered. Also see blk_stop_queue(). Queue lock must be held.
218 void blk_start_queue(struct request_queue
*q
)
220 WARN_ON(!irqs_disabled());
222 queue_flag_clear(QUEUE_FLAG_STOPPED
, q
);
225 EXPORT_SYMBOL(blk_start_queue
);
228 * blk_stop_queue - stop a queue
229 * @q: The &struct request_queue in question
232 * The Linux block layer assumes that a block driver will consume all
233 * entries on the request queue when the request_fn strategy is called.
234 * Often this will not happen, because of hardware limitations (queue
235 * depth settings). If a device driver gets a 'queue full' response,
236 * or if it simply chooses not to queue more I/O at one point, it can
237 * call this function to prevent the request_fn from being called until
238 * the driver has signalled it's ready to go again. This happens by calling
239 * blk_start_queue() to restart queue operations. Queue lock must be held.
241 void blk_stop_queue(struct request_queue
*q
)
243 cancel_delayed_work(&q
->delay_work
);
244 queue_flag_set(QUEUE_FLAG_STOPPED
, q
);
246 EXPORT_SYMBOL(blk_stop_queue
);
249 * blk_sync_queue - cancel any pending callbacks on a queue
253 * The block layer may perform asynchronous callback activity
254 * on a queue, such as calling the unplug function after a timeout.
255 * A block device may call blk_sync_queue to ensure that any
256 * such activity is cancelled, thus allowing it to release resources
257 * that the callbacks might use. The caller must already have made sure
258 * that its ->make_request_fn will not re-add plugging prior to calling
261 * This function does not cancel any asynchronous activity arising
262 * out of elevator or throttling code. That would require elevator_exit()
263 * and blkcg_exit_queue() to be called with queue lock initialized.
266 void blk_sync_queue(struct request_queue
*q
)
268 del_timer_sync(&q
->timeout
);
271 struct blk_mq_hw_ctx
*hctx
;
274 queue_for_each_hw_ctx(q
, hctx
, i
) {
275 cancel_delayed_work_sync(&hctx
->run_work
);
276 cancel_delayed_work_sync(&hctx
->delay_work
);
279 cancel_delayed_work_sync(&q
->delay_work
);
282 EXPORT_SYMBOL(blk_sync_queue
);
285 * __blk_run_queue_uncond - run a queue whether or not it has been stopped
286 * @q: The queue to run
289 * Invoke request handling on a queue if there are any pending requests.
290 * May be used to restart request handling after a request has completed.
291 * This variant runs the queue whether or not the queue has been
292 * stopped. Must be called with the queue lock held and interrupts
293 * disabled. See also @blk_run_queue.
295 inline void __blk_run_queue_uncond(struct request_queue
*q
)
297 if (unlikely(blk_queue_dead(q
)))
301 * Some request_fn implementations, e.g. scsi_request_fn(), unlock
302 * the queue lock internally. As a result multiple threads may be
303 * running such a request function concurrently. Keep track of the
304 * number of active request_fn invocations such that blk_drain_queue()
305 * can wait until all these request_fn calls have finished.
307 q
->request_fn_active
++;
309 q
->request_fn_active
--;
311 EXPORT_SYMBOL_GPL(__blk_run_queue_uncond
);
314 * __blk_run_queue - run a single device queue
315 * @q: The queue to run
318 * See @blk_run_queue. This variant must be called with the queue lock
319 * held and interrupts disabled.
321 void __blk_run_queue(struct request_queue
*q
)
323 if (unlikely(blk_queue_stopped(q
)))
326 __blk_run_queue_uncond(q
);
328 EXPORT_SYMBOL(__blk_run_queue
);
331 * blk_run_queue_async - run a single device queue in workqueue context
332 * @q: The queue to run
335 * Tells kblockd to perform the equivalent of @blk_run_queue on behalf
336 * of us. The caller must hold the queue lock.
338 void blk_run_queue_async(struct request_queue
*q
)
340 if (likely(!blk_queue_stopped(q
) && !blk_queue_dead(q
)))
341 mod_delayed_work(kblockd_workqueue
, &q
->delay_work
, 0);
343 EXPORT_SYMBOL(blk_run_queue_async
);
346 * blk_run_queue - run a single device queue
347 * @q: The queue to run
350 * Invoke request handling on this queue, if it has pending work to do.
351 * May be used to restart queueing when a request has completed.
353 void blk_run_queue(struct request_queue
*q
)
357 spin_lock_irqsave(q
->queue_lock
, flags
);
359 spin_unlock_irqrestore(q
->queue_lock
, flags
);
361 EXPORT_SYMBOL(blk_run_queue
);
363 void blk_put_queue(struct request_queue
*q
)
365 kobject_put(&q
->kobj
);
367 EXPORT_SYMBOL(blk_put_queue
);
370 * __blk_drain_queue - drain requests from request_queue
372 * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
374 * Drain requests from @q. If @drain_all is set, all requests are drained.
375 * If not, only ELVPRIV requests are drained. The caller is responsible
376 * for ensuring that no new requests which need to be drained are queued.
378 static void __blk_drain_queue(struct request_queue
*q
, bool drain_all
)
379 __releases(q
->queue_lock
)
380 __acquires(q
->queue_lock
)
384 lockdep_assert_held(q
->queue_lock
);
390 * The caller might be trying to drain @q before its
391 * elevator is initialized.
394 elv_drain_elevator(q
);
396 blkcg_drain_queue(q
);
399 * This function might be called on a queue which failed
400 * driver init after queue creation or is not yet fully
401 * active yet. Some drivers (e.g. fd and loop) get unhappy
402 * in such cases. Kick queue iff dispatch queue has
403 * something on it and @q has request_fn set.
405 if (!list_empty(&q
->queue_head
) && q
->request_fn
)
408 drain
|= q
->nr_rqs_elvpriv
;
409 drain
|= q
->request_fn_active
;
412 * Unfortunately, requests are queued at and tracked from
413 * multiple places and there's no single counter which can
414 * be drained. Check all the queues and counters.
417 struct blk_flush_queue
*fq
= blk_get_flush_queue(q
, NULL
);
418 drain
|= !list_empty(&q
->queue_head
);
419 for (i
= 0; i
< 2; i
++) {
420 drain
|= q
->nr_rqs
[i
];
421 drain
|= q
->in_flight
[i
];
423 drain
|= !list_empty(&fq
->flush_queue
[i
]);
430 spin_unlock_irq(q
->queue_lock
);
434 spin_lock_irq(q
->queue_lock
);
438 * With queue marked dead, any woken up waiter will fail the
439 * allocation path, so the wakeup chaining is lost and we're
440 * left with hung waiters. We need to wake up those waiters.
443 struct request_list
*rl
;
445 blk_queue_for_each_rl(rl
, q
)
446 for (i
= 0; i
< ARRAY_SIZE(rl
->wait
); i
++)
447 wake_up_all(&rl
->wait
[i
]);
452 * blk_queue_bypass_start - enter queue bypass mode
453 * @q: queue of interest
455 * In bypass mode, only the dispatch FIFO queue of @q is used. This
456 * function makes @q enter bypass mode and drains all requests which were
457 * throttled or issued before. On return, it's guaranteed that no request
458 * is being throttled or has ELVPRIV set and blk_queue_bypass() %true
459 * inside queue or RCU read lock.
461 void blk_queue_bypass_start(struct request_queue
*q
)
463 spin_lock_irq(q
->queue_lock
);
465 queue_flag_set(QUEUE_FLAG_BYPASS
, q
);
466 spin_unlock_irq(q
->queue_lock
);
469 * Queues start drained. Skip actual draining till init is
470 * complete. This avoids lenghty delays during queue init which
471 * can happen many times during boot.
473 if (blk_queue_init_done(q
)) {
474 spin_lock_irq(q
->queue_lock
);
475 __blk_drain_queue(q
, false);
476 spin_unlock_irq(q
->queue_lock
);
478 /* ensure blk_queue_bypass() is %true inside RCU read lock */
482 EXPORT_SYMBOL_GPL(blk_queue_bypass_start
);
485 * blk_queue_bypass_end - leave queue bypass mode
486 * @q: queue of interest
488 * Leave bypass mode and restore the normal queueing behavior.
490 void blk_queue_bypass_end(struct request_queue
*q
)
492 spin_lock_irq(q
->queue_lock
);
493 if (!--q
->bypass_depth
)
494 queue_flag_clear(QUEUE_FLAG_BYPASS
, q
);
495 WARN_ON_ONCE(q
->bypass_depth
< 0);
496 spin_unlock_irq(q
->queue_lock
);
498 EXPORT_SYMBOL_GPL(blk_queue_bypass_end
);
500 void blk_set_queue_dying(struct request_queue
*q
)
502 queue_flag_set_unlocked(QUEUE_FLAG_DYING
, q
);
505 blk_mq_wake_waiters(q
);
507 struct request_list
*rl
;
509 blk_queue_for_each_rl(rl
, q
) {
511 wake_up(&rl
->wait
[BLK_RW_SYNC
]);
512 wake_up(&rl
->wait
[BLK_RW_ASYNC
]);
517 EXPORT_SYMBOL_GPL(blk_set_queue_dying
);
520 * blk_cleanup_queue - shutdown a request queue
521 * @q: request queue to shutdown
523 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
524 * put it. All future requests will be failed immediately with -ENODEV.
526 void blk_cleanup_queue(struct request_queue
*q
)
528 spinlock_t
*lock
= q
->queue_lock
;
530 /* mark @q DYING, no new request or merges will be allowed afterwards */
531 mutex_lock(&q
->sysfs_lock
);
532 blk_set_queue_dying(q
);
536 * A dying queue is permanently in bypass mode till released. Note
537 * that, unlike blk_queue_bypass_start(), we aren't performing
538 * synchronize_rcu() after entering bypass mode to avoid the delay
539 * as some drivers create and destroy a lot of queues while
540 * probing. This is still safe because blk_release_queue() will be
541 * called only after the queue refcnt drops to zero and nothing,
542 * RCU or not, would be traversing the queue by then.
545 queue_flag_set(QUEUE_FLAG_BYPASS
, q
);
547 queue_flag_set(QUEUE_FLAG_NOMERGES
, q
);
548 queue_flag_set(QUEUE_FLAG_NOXMERGES
, q
);
549 queue_flag_set(QUEUE_FLAG_DYING
, q
);
550 spin_unlock_irq(lock
);
551 mutex_unlock(&q
->sysfs_lock
);
554 * Drain all requests queued before DYING marking. Set DEAD flag to
555 * prevent that q->request_fn() gets invoked after draining finished.
560 __blk_drain_queue(q
, true);
561 queue_flag_set(QUEUE_FLAG_DEAD
, q
);
562 spin_unlock_irq(lock
);
564 /* @q won't process any more request, flush async actions */
565 del_timer_sync(&q
->backing_dev_info
.laptop_mode_wb_timer
);
569 blk_mq_free_queue(q
);
570 percpu_ref_exit(&q
->q_usage_counter
);
573 if (q
->queue_lock
!= &q
->__queue_lock
)
574 q
->queue_lock
= &q
->__queue_lock
;
575 spin_unlock_irq(lock
);
577 bdi_destroy(&q
->backing_dev_info
);
579 /* @q is and will stay empty, shutdown and put */
582 EXPORT_SYMBOL(blk_cleanup_queue
);
584 /* Allocate memory local to the request queue */
585 static void *alloc_request_struct(gfp_t gfp_mask
, void *data
)
587 int nid
= (int)(long)data
;
588 return kmem_cache_alloc_node(request_cachep
, gfp_mask
, nid
);
591 static void free_request_struct(void *element
, void *unused
)
593 kmem_cache_free(request_cachep
, element
);
596 int blk_init_rl(struct request_list
*rl
, struct request_queue
*q
,
599 if (unlikely(rl
->rq_pool
))
603 rl
->count
[BLK_RW_SYNC
] = rl
->count
[BLK_RW_ASYNC
] = 0;
604 rl
->starved
[BLK_RW_SYNC
] = rl
->starved
[BLK_RW_ASYNC
] = 0;
605 init_waitqueue_head(&rl
->wait
[BLK_RW_SYNC
]);
606 init_waitqueue_head(&rl
->wait
[BLK_RW_ASYNC
]);
608 rl
->rq_pool
= mempool_create_node(BLKDEV_MIN_RQ
, alloc_request_struct
,
610 (void *)(long)q
->node
, gfp_mask
,
618 void blk_exit_rl(struct request_list
*rl
)
621 mempool_destroy(rl
->rq_pool
);
624 struct request_queue
*blk_alloc_queue(gfp_t gfp_mask
)
626 return blk_alloc_queue_node(gfp_mask
, NUMA_NO_NODE
);
628 EXPORT_SYMBOL(blk_alloc_queue
);
630 int blk_queue_enter(struct request_queue
*q
, gfp_t gfp
)
635 if (percpu_ref_tryget_live(&q
->q_usage_counter
))
638 if (!(gfp
& __GFP_WAIT
))
641 ret
= wait_event_interruptible(q
->mq_freeze_wq
,
642 !atomic_read(&q
->mq_freeze_depth
) ||
644 if (blk_queue_dying(q
))
651 void blk_queue_exit(struct request_queue
*q
)
653 percpu_ref_put(&q
->q_usage_counter
);
656 static void blk_queue_usage_counter_release(struct percpu_ref
*ref
)
658 struct request_queue
*q
=
659 container_of(ref
, struct request_queue
, q_usage_counter
);
661 wake_up_all(&q
->mq_freeze_wq
);
664 struct request_queue
*blk_alloc_queue_node(gfp_t gfp_mask
, int node_id
)
666 struct request_queue
*q
;
669 q
= kmem_cache_alloc_node(blk_requestq_cachep
,
670 gfp_mask
| __GFP_ZERO
, node_id
);
674 q
->id
= ida_simple_get(&blk_queue_ida
, 0, 0, gfp_mask
);
678 q
->bio_split
= bioset_create(BIO_POOL_SIZE
, 0);
682 q
->backing_dev_info
.ra_pages
=
683 (VM_MAX_READAHEAD
* 1024) / PAGE_CACHE_SIZE
;
684 q
->backing_dev_info
.capabilities
= BDI_CAP_CGROUP_WRITEBACK
;
685 q
->backing_dev_info
.name
= "block";
688 err
= bdi_init(&q
->backing_dev_info
);
692 setup_timer(&q
->backing_dev_info
.laptop_mode_wb_timer
,
693 laptop_mode_timer_fn
, (unsigned long) q
);
694 setup_timer(&q
->timeout
, blk_rq_timed_out_timer
, (unsigned long) q
);
695 INIT_LIST_HEAD(&q
->queue_head
);
696 INIT_LIST_HEAD(&q
->timeout_list
);
697 INIT_LIST_HEAD(&q
->icq_list
);
698 #ifdef CONFIG_BLK_CGROUP
699 INIT_LIST_HEAD(&q
->blkg_list
);
701 INIT_DELAYED_WORK(&q
->delay_work
, blk_delay_work
);
703 kobject_init(&q
->kobj
, &blk_queue_ktype
);
705 mutex_init(&q
->sysfs_lock
);
706 spin_lock_init(&q
->__queue_lock
);
709 * By default initialize queue_lock to internal lock and driver can
710 * override it later if need be.
712 q
->queue_lock
= &q
->__queue_lock
;
715 * A queue starts its life with bypass turned on to avoid
716 * unnecessary bypass on/off overhead and nasty surprises during
717 * init. The initial bypass will be finished when the queue is
718 * registered by blk_register_queue().
721 __set_bit(QUEUE_FLAG_BYPASS
, &q
->queue_flags
);
723 init_waitqueue_head(&q
->mq_freeze_wq
);
726 * Init percpu_ref in atomic mode so that it's faster to shutdown.
727 * See blk_register_queue() for details.
729 if (percpu_ref_init(&q
->q_usage_counter
,
730 blk_queue_usage_counter_release
,
731 PERCPU_REF_INIT_ATOMIC
, GFP_KERNEL
))
734 if (blkcg_init_queue(q
))
740 percpu_ref_exit(&q
->q_usage_counter
);
742 bdi_destroy(&q
->backing_dev_info
);
744 bioset_free(q
->bio_split
);
746 ida_simple_remove(&blk_queue_ida
, q
->id
);
748 kmem_cache_free(blk_requestq_cachep
, q
);
751 EXPORT_SYMBOL(blk_alloc_queue_node
);
754 * blk_init_queue - prepare a request queue for use with a block device
755 * @rfn: The function to be called to process requests that have been
756 * placed on the queue.
757 * @lock: Request queue spin lock
760 * If a block device wishes to use the standard request handling procedures,
761 * which sorts requests and coalesces adjacent requests, then it must
762 * call blk_init_queue(). The function @rfn will be called when there
763 * are requests on the queue that need to be processed. If the device
764 * supports plugging, then @rfn may not be called immediately when requests
765 * are available on the queue, but may be called at some time later instead.
766 * Plugged queues are generally unplugged when a buffer belonging to one
767 * of the requests on the queue is needed, or due to memory pressure.
769 * @rfn is not required, or even expected, to remove all requests off the
770 * queue, but only as many as it can handle at a time. If it does leave
771 * requests on the queue, it is responsible for arranging that the requests
772 * get dealt with eventually.
774 * The queue spin lock must be held while manipulating the requests on the
775 * request queue; this lock will be taken also from interrupt context, so irq
776 * disabling is needed for it.
778 * Function returns a pointer to the initialized request queue, or %NULL if
782 * blk_init_queue() must be paired with a blk_cleanup_queue() call
783 * when the block device is deactivated (such as at module unload).
786 struct request_queue
*blk_init_queue(request_fn_proc
*rfn
, spinlock_t
*lock
)
788 return blk_init_queue_node(rfn
, lock
, NUMA_NO_NODE
);
790 EXPORT_SYMBOL(blk_init_queue
);
792 struct request_queue
*
793 blk_init_queue_node(request_fn_proc
*rfn
, spinlock_t
*lock
, int node_id
)
795 struct request_queue
*uninit_q
, *q
;
797 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, node_id
);
801 q
= blk_init_allocated_queue(uninit_q
, rfn
, lock
);
803 blk_cleanup_queue(uninit_q
);
807 EXPORT_SYMBOL(blk_init_queue_node
);
809 static void blk_queue_bio(struct request_queue
*q
, struct bio
*bio
);
811 struct request_queue
*
812 blk_init_allocated_queue(struct request_queue
*q
, request_fn_proc
*rfn
,
818 q
->fq
= blk_alloc_flush_queue(q
, NUMA_NO_NODE
, 0);
822 if (blk_init_rl(&q
->root_rl
, q
, GFP_KERNEL
))
826 q
->prep_rq_fn
= NULL
;
827 q
->unprep_rq_fn
= NULL
;
828 q
->queue_flags
|= QUEUE_FLAG_DEFAULT
;
830 /* Override internal queue lock with supplied lock pointer */
832 q
->queue_lock
= lock
;
835 * This also sets hw/phys segments, boundary and size
837 blk_queue_make_request(q
, blk_queue_bio
);
839 q
->sg_reserved_size
= INT_MAX
;
841 /* Protect q->elevator from elevator_change */
842 mutex_lock(&q
->sysfs_lock
);
845 if (elevator_init(q
, NULL
)) {
846 mutex_unlock(&q
->sysfs_lock
);
850 mutex_unlock(&q
->sysfs_lock
);
855 blk_free_flush_queue(q
->fq
);
858 EXPORT_SYMBOL(blk_init_allocated_queue
);
860 bool blk_get_queue(struct request_queue
*q
)
862 if (likely(!blk_queue_dying(q
))) {
869 EXPORT_SYMBOL(blk_get_queue
);
871 static inline void blk_free_request(struct request_list
*rl
, struct request
*rq
)
873 if (rq
->cmd_flags
& REQ_ELVPRIV
) {
874 elv_put_request(rl
->q
, rq
);
876 put_io_context(rq
->elv
.icq
->ioc
);
879 mempool_free(rq
, rl
->rq_pool
);
883 * ioc_batching returns true if the ioc is a valid batching request and
884 * should be given priority access to a request.
886 static inline int ioc_batching(struct request_queue
*q
, struct io_context
*ioc
)
892 * Make sure the process is able to allocate at least 1 request
893 * even if the batch times out, otherwise we could theoretically
896 return ioc
->nr_batch_requests
== q
->nr_batching
||
897 (ioc
->nr_batch_requests
> 0
898 && time_before(jiffies
, ioc
->last_waited
+ BLK_BATCH_TIME
));
902 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
903 * will cause the process to be a "batcher" on all queues in the system. This
904 * is the behaviour we want though - once it gets a wakeup it should be given
907 static void ioc_set_batching(struct request_queue
*q
, struct io_context
*ioc
)
909 if (!ioc
|| ioc_batching(q
, ioc
))
912 ioc
->nr_batch_requests
= q
->nr_batching
;
913 ioc
->last_waited
= jiffies
;
916 static void __freed_request(struct request_list
*rl
, int sync
)
918 struct request_queue
*q
= rl
->q
;
920 if (rl
->count
[sync
] < queue_congestion_off_threshold(q
))
921 blk_clear_congested(rl
, sync
);
923 if (rl
->count
[sync
] + 1 <= q
->nr_requests
) {
924 if (waitqueue_active(&rl
->wait
[sync
]))
925 wake_up(&rl
->wait
[sync
]);
927 blk_clear_rl_full(rl
, sync
);
932 * A request has just been released. Account for it, update the full and
933 * congestion status, wake up any waiters. Called under q->queue_lock.
935 static void freed_request(struct request_list
*rl
, unsigned int flags
)
937 struct request_queue
*q
= rl
->q
;
938 int sync
= rw_is_sync(flags
);
942 if (flags
& REQ_ELVPRIV
)
945 __freed_request(rl
, sync
);
947 if (unlikely(rl
->starved
[sync
^ 1]))
948 __freed_request(rl
, sync
^ 1);
951 int blk_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
953 struct request_list
*rl
;
954 int on_thresh
, off_thresh
;
956 spin_lock_irq(q
->queue_lock
);
958 blk_queue_congestion_threshold(q
);
959 on_thresh
= queue_congestion_on_threshold(q
);
960 off_thresh
= queue_congestion_off_threshold(q
);
962 blk_queue_for_each_rl(rl
, q
) {
963 if (rl
->count
[BLK_RW_SYNC
] >= on_thresh
)
964 blk_set_congested(rl
, BLK_RW_SYNC
);
965 else if (rl
->count
[BLK_RW_SYNC
] < off_thresh
)
966 blk_clear_congested(rl
, BLK_RW_SYNC
);
968 if (rl
->count
[BLK_RW_ASYNC
] >= on_thresh
)
969 blk_set_congested(rl
, BLK_RW_ASYNC
);
970 else if (rl
->count
[BLK_RW_ASYNC
] < off_thresh
)
971 blk_clear_congested(rl
, BLK_RW_ASYNC
);
973 if (rl
->count
[BLK_RW_SYNC
] >= q
->nr_requests
) {
974 blk_set_rl_full(rl
, BLK_RW_SYNC
);
976 blk_clear_rl_full(rl
, BLK_RW_SYNC
);
977 wake_up(&rl
->wait
[BLK_RW_SYNC
]);
980 if (rl
->count
[BLK_RW_ASYNC
] >= q
->nr_requests
) {
981 blk_set_rl_full(rl
, BLK_RW_ASYNC
);
983 blk_clear_rl_full(rl
, BLK_RW_ASYNC
);
984 wake_up(&rl
->wait
[BLK_RW_ASYNC
]);
988 spin_unlock_irq(q
->queue_lock
);
993 * Determine if elevator data should be initialized when allocating the
994 * request associated with @bio.
996 static bool blk_rq_should_init_elevator(struct bio
*bio
)
1002 * Flush requests do not use the elevator so skip initialization.
1003 * This allows a request to share the flush and elevator data.
1005 if (bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
))
1012 * rq_ioc - determine io_context for request allocation
1013 * @bio: request being allocated is for this bio (can be %NULL)
1015 * Determine io_context to use for request allocation for @bio. May return
1016 * %NULL if %current->io_context doesn't exist.
1018 static struct io_context
*rq_ioc(struct bio
*bio
)
1020 #ifdef CONFIG_BLK_CGROUP
1021 if (bio
&& bio
->bi_ioc
)
1024 return current
->io_context
;
1028 * __get_request - get a free request
1029 * @rl: request list to allocate from
1030 * @rw_flags: RW and SYNC flags
1031 * @bio: bio to allocate request for (can be %NULL)
1032 * @gfp_mask: allocation mask
1034 * Get a free request from @q. This function may fail under memory
1035 * pressure or if @q is dead.
1037 * Must be called with @q->queue_lock held and,
1038 * Returns ERR_PTR on failure, with @q->queue_lock held.
1039 * Returns request pointer on success, with @q->queue_lock *not held*.
1041 static struct request
*__get_request(struct request_list
*rl
, int rw_flags
,
1042 struct bio
*bio
, gfp_t gfp_mask
)
1044 struct request_queue
*q
= rl
->q
;
1046 struct elevator_type
*et
= q
->elevator
->type
;
1047 struct io_context
*ioc
= rq_ioc(bio
);
1048 struct io_cq
*icq
= NULL
;
1049 const bool is_sync
= rw_is_sync(rw_flags
) != 0;
1052 if (unlikely(blk_queue_dying(q
)))
1053 return ERR_PTR(-ENODEV
);
1055 may_queue
= elv_may_queue(q
, rw_flags
);
1056 if (may_queue
== ELV_MQUEUE_NO
)
1059 if (rl
->count
[is_sync
]+1 >= queue_congestion_on_threshold(q
)) {
1060 if (rl
->count
[is_sync
]+1 >= q
->nr_requests
) {
1062 * The queue will fill after this allocation, so set
1063 * it as full, and mark this process as "batching".
1064 * This process will be allowed to complete a batch of
1065 * requests, others will be blocked.
1067 if (!blk_rl_full(rl
, is_sync
)) {
1068 ioc_set_batching(q
, ioc
);
1069 blk_set_rl_full(rl
, is_sync
);
1071 if (may_queue
!= ELV_MQUEUE_MUST
1072 && !ioc_batching(q
, ioc
)) {
1074 * The queue is full and the allocating
1075 * process is not a "batcher", and not
1076 * exempted by the IO scheduler
1078 return ERR_PTR(-ENOMEM
);
1082 blk_set_congested(rl
, is_sync
);
1086 * Only allow batching queuers to allocate up to 50% over the defined
1087 * limit of requests, otherwise we could have thousands of requests
1088 * allocated with any setting of ->nr_requests
1090 if (rl
->count
[is_sync
] >= (3 * q
->nr_requests
/ 2))
1091 return ERR_PTR(-ENOMEM
);
1093 q
->nr_rqs
[is_sync
]++;
1094 rl
->count
[is_sync
]++;
1095 rl
->starved
[is_sync
] = 0;
1098 * Decide whether the new request will be managed by elevator. If
1099 * so, mark @rw_flags and increment elvpriv. Non-zero elvpriv will
1100 * prevent the current elevator from being destroyed until the new
1101 * request is freed. This guarantees icq's won't be destroyed and
1102 * makes creating new ones safe.
1104 * Also, lookup icq while holding queue_lock. If it doesn't exist,
1105 * it will be created after releasing queue_lock.
1107 if (blk_rq_should_init_elevator(bio
) && !blk_queue_bypass(q
)) {
1108 rw_flags
|= REQ_ELVPRIV
;
1109 q
->nr_rqs_elvpriv
++;
1110 if (et
->icq_cache
&& ioc
)
1111 icq
= ioc_lookup_icq(ioc
, q
);
1114 if (blk_queue_io_stat(q
))
1115 rw_flags
|= REQ_IO_STAT
;
1116 spin_unlock_irq(q
->queue_lock
);
1118 /* allocate and init request */
1119 rq
= mempool_alloc(rl
->rq_pool
, gfp_mask
);
1124 blk_rq_set_rl(rq
, rl
);
1125 rq
->cmd_flags
= rw_flags
| REQ_ALLOCED
;
1128 if (rw_flags
& REQ_ELVPRIV
) {
1129 if (unlikely(et
->icq_cache
&& !icq
)) {
1131 icq
= ioc_create_icq(ioc
, q
, gfp_mask
);
1137 if (unlikely(elv_set_request(q
, rq
, bio
, gfp_mask
)))
1140 /* @rq->elv.icq holds io_context until @rq is freed */
1142 get_io_context(icq
->ioc
);
1146 * ioc may be NULL here, and ioc_batching will be false. That's
1147 * OK, if the queue is under the request limit then requests need
1148 * not count toward the nr_batch_requests limit. There will always
1149 * be some limit enforced by BLK_BATCH_TIME.
1151 if (ioc_batching(q
, ioc
))
1152 ioc
->nr_batch_requests
--;
1154 trace_block_getrq(q
, bio
, rw_flags
& 1);
1159 * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed
1160 * and may fail indefinitely under memory pressure and thus
1161 * shouldn't stall IO. Treat this request as !elvpriv. This will
1162 * disturb iosched and blkcg but weird is bettern than dead.
1164 printk_ratelimited(KERN_WARNING
"%s: dev %s: request aux data allocation failed, iosched may be disturbed\n",
1165 __func__
, dev_name(q
->backing_dev_info
.dev
));
1167 rq
->cmd_flags
&= ~REQ_ELVPRIV
;
1170 spin_lock_irq(q
->queue_lock
);
1171 q
->nr_rqs_elvpriv
--;
1172 spin_unlock_irq(q
->queue_lock
);
1177 * Allocation failed presumably due to memory. Undo anything we
1178 * might have messed up.
1180 * Allocating task should really be put onto the front of the wait
1181 * queue, but this is pretty rare.
1183 spin_lock_irq(q
->queue_lock
);
1184 freed_request(rl
, rw_flags
);
1187 * in the very unlikely event that allocation failed and no
1188 * requests for this direction was pending, mark us starved so that
1189 * freeing of a request in the other direction will notice
1190 * us. another possible fix would be to split the rq mempool into
1194 if (unlikely(rl
->count
[is_sync
] == 0))
1195 rl
->starved
[is_sync
] = 1;
1196 return ERR_PTR(-ENOMEM
);
1200 * get_request - get a free request
1201 * @q: request_queue to allocate request from
1202 * @rw_flags: RW and SYNC flags
1203 * @bio: bio to allocate request for (can be %NULL)
1204 * @gfp_mask: allocation mask
1206 * Get a free request from @q. If %__GFP_WAIT is set in @gfp_mask, this
1207 * function keeps retrying under memory pressure and fails iff @q is dead.
1209 * Must be called with @q->queue_lock held and,
1210 * Returns ERR_PTR on failure, with @q->queue_lock held.
1211 * Returns request pointer on success, with @q->queue_lock *not held*.
1213 static struct request
*get_request(struct request_queue
*q
, int rw_flags
,
1214 struct bio
*bio
, gfp_t gfp_mask
)
1216 const bool is_sync
= rw_is_sync(rw_flags
) != 0;
1218 struct request_list
*rl
;
1221 rl
= blk_get_rl(q
, bio
); /* transferred to @rq on success */
1223 rq
= __get_request(rl
, rw_flags
, bio
, gfp_mask
);
1227 if (!(gfp_mask
& __GFP_WAIT
) || unlikely(blk_queue_dying(q
))) {
1232 /* wait on @rl and retry */
1233 prepare_to_wait_exclusive(&rl
->wait
[is_sync
], &wait
,
1234 TASK_UNINTERRUPTIBLE
);
1236 trace_block_sleeprq(q
, bio
, rw_flags
& 1);
1238 spin_unlock_irq(q
->queue_lock
);
1242 * After sleeping, we become a "batching" process and will be able
1243 * to allocate at least one request, and up to a big batch of them
1244 * for a small period time. See ioc_batching, ioc_set_batching
1246 ioc_set_batching(q
, current
->io_context
);
1248 spin_lock_irq(q
->queue_lock
);
1249 finish_wait(&rl
->wait
[is_sync
], &wait
);
1254 static struct request
*blk_old_get_request(struct request_queue
*q
, int rw
,
1259 BUG_ON(rw
!= READ
&& rw
!= WRITE
);
1261 /* create ioc upfront */
1262 create_io_context(gfp_mask
, q
->node
);
1264 spin_lock_irq(q
->queue_lock
);
1265 rq
= get_request(q
, rw
, NULL
, gfp_mask
);
1267 spin_unlock_irq(q
->queue_lock
);
1268 /* q->queue_lock is unlocked at this point */
1273 struct request
*blk_get_request(struct request_queue
*q
, int rw
, gfp_t gfp_mask
)
1276 return blk_mq_alloc_request(q
, rw
, gfp_mask
, false);
1278 return blk_old_get_request(q
, rw
, gfp_mask
);
1280 EXPORT_SYMBOL(blk_get_request
);
1283 * blk_make_request - given a bio, allocate a corresponding struct request.
1284 * @q: target request queue
1285 * @bio: The bio describing the memory mappings that will be submitted for IO.
1286 * It may be a chained-bio properly constructed by block/bio layer.
1287 * @gfp_mask: gfp flags to be used for memory allocation
1289 * blk_make_request is the parallel of generic_make_request for BLOCK_PC
1290 * type commands. Where the struct request needs to be farther initialized by
1291 * the caller. It is passed a &struct bio, which describes the memory info of
1294 * The caller of blk_make_request must make sure that bi_io_vec
1295 * are set to describe the memory buffers. That bio_data_dir() will return
1296 * the needed direction of the request. (And all bio's in the passed bio-chain
1297 * are properly set accordingly)
1299 * If called under none-sleepable conditions, mapped bio buffers must not
1300 * need bouncing, by calling the appropriate masked or flagged allocator,
1301 * suitable for the target device. Otherwise the call to blk_queue_bounce will
1304 * WARNING: When allocating/cloning a bio-chain, careful consideration should be
1305 * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for
1306 * anything but the first bio in the chain. Otherwise you risk waiting for IO
1307 * completion of a bio that hasn't been submitted yet, thus resulting in a
1308 * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead
1309 * of bio_alloc(), as that avoids the mempool deadlock.
1310 * If possible a big IO should be split into smaller parts when allocation
1311 * fails. Partial allocation should not be an error, or you risk a live-lock.
1313 struct request
*blk_make_request(struct request_queue
*q
, struct bio
*bio
,
1316 struct request
*rq
= blk_get_request(q
, bio_data_dir(bio
), gfp_mask
);
1321 blk_rq_set_block_pc(rq
);
1324 struct bio
*bounce_bio
= bio
;
1327 blk_queue_bounce(q
, &bounce_bio
);
1328 ret
= blk_rq_append_bio(q
, rq
, bounce_bio
);
1329 if (unlikely(ret
)) {
1330 blk_put_request(rq
);
1331 return ERR_PTR(ret
);
1337 EXPORT_SYMBOL(blk_make_request
);
1340 * blk_rq_set_block_pc - initialize a request to type BLOCK_PC
1341 * @rq: request to be initialized
1344 void blk_rq_set_block_pc(struct request
*rq
)
1346 rq
->cmd_type
= REQ_TYPE_BLOCK_PC
;
1348 rq
->__sector
= (sector_t
) -1;
1349 rq
->bio
= rq
->biotail
= NULL
;
1350 memset(rq
->__cmd
, 0, sizeof(rq
->__cmd
));
1352 EXPORT_SYMBOL(blk_rq_set_block_pc
);
1355 * blk_requeue_request - put a request back on queue
1356 * @q: request queue where request should be inserted
1357 * @rq: request to be inserted
1360 * Drivers often keep queueing requests until the hardware cannot accept
1361 * more, when that condition happens we need to put the request back
1362 * on the queue. Must be called with queue lock held.
1364 void blk_requeue_request(struct request_queue
*q
, struct request
*rq
)
1366 blk_delete_timer(rq
);
1367 blk_clear_rq_complete(rq
);
1368 trace_block_rq_requeue(q
, rq
);
1370 if (rq
->cmd_flags
& REQ_QUEUED
)
1371 blk_queue_end_tag(q
, rq
);
1373 BUG_ON(blk_queued_rq(rq
));
1375 elv_requeue_request(q
, rq
);
1377 EXPORT_SYMBOL(blk_requeue_request
);
1379 static void add_acct_request(struct request_queue
*q
, struct request
*rq
,
1382 blk_account_io_start(rq
, true);
1383 __elv_add_request(q
, rq
, where
);
1386 static void part_round_stats_single(int cpu
, struct hd_struct
*part
,
1391 if (now
== part
->stamp
)
1394 inflight
= part_in_flight(part
);
1396 __part_stat_add(cpu
, part
, time_in_queue
,
1397 inflight
* (now
- part
->stamp
));
1398 __part_stat_add(cpu
, part
, io_ticks
, (now
- part
->stamp
));
1404 * part_round_stats() - Round off the performance stats on a struct disk_stats.
1405 * @cpu: cpu number for stats access
1406 * @part: target partition
1408 * The average IO queue length and utilisation statistics are maintained
1409 * by observing the current state of the queue length and the amount of
1410 * time it has been in this state for.
1412 * Normally, that accounting is done on IO completion, but that can result
1413 * in more than a second's worth of IO being accounted for within any one
1414 * second, leading to >100% utilisation. To deal with that, we call this
1415 * function to do a round-off before returning the results when reading
1416 * /proc/diskstats. This accounts immediately for all queue usage up to
1417 * the current jiffies and restarts the counters again.
1419 void part_round_stats(int cpu
, struct hd_struct
*part
)
1421 unsigned long now
= jiffies
;
1424 part_round_stats_single(cpu
, &part_to_disk(part
)->part0
, now
);
1425 part_round_stats_single(cpu
, part
, now
);
1427 EXPORT_SYMBOL_GPL(part_round_stats
);
1430 static void blk_pm_put_request(struct request
*rq
)
1432 if (rq
->q
->dev
&& !(rq
->cmd_flags
& REQ_PM
) && !--rq
->q
->nr_pending
)
1433 pm_runtime_mark_last_busy(rq
->q
->dev
);
1436 static inline void blk_pm_put_request(struct request
*rq
) {}
1440 * queue lock must be held
1442 void __blk_put_request(struct request_queue
*q
, struct request
*req
)
1448 blk_mq_free_request(req
);
1452 blk_pm_put_request(req
);
1454 elv_completed_request(q
, req
);
1456 /* this is a bio leak */
1457 WARN_ON(req
->bio
!= NULL
);
1460 * Request may not have originated from ll_rw_blk. if not,
1461 * it didn't come out of our reserved rq pools
1463 if (req
->cmd_flags
& REQ_ALLOCED
) {
1464 unsigned int flags
= req
->cmd_flags
;
1465 struct request_list
*rl
= blk_rq_rl(req
);
1467 BUG_ON(!list_empty(&req
->queuelist
));
1468 BUG_ON(ELV_ON_HASH(req
));
1470 blk_free_request(rl
, req
);
1471 freed_request(rl
, flags
);
1475 EXPORT_SYMBOL_GPL(__blk_put_request
);
1477 void blk_put_request(struct request
*req
)
1479 struct request_queue
*q
= req
->q
;
1482 blk_mq_free_request(req
);
1484 unsigned long flags
;
1486 spin_lock_irqsave(q
->queue_lock
, flags
);
1487 __blk_put_request(q
, req
);
1488 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1491 EXPORT_SYMBOL(blk_put_request
);
1494 * blk_add_request_payload - add a payload to a request
1495 * @rq: request to update
1496 * @page: page backing the payload
1497 * @len: length of the payload.
1499 * This allows to later add a payload to an already submitted request by
1500 * a block driver. The driver needs to take care of freeing the payload
1503 * Note that this is a quite horrible hack and nothing but handling of
1504 * discard requests should ever use it.
1506 void blk_add_request_payload(struct request
*rq
, struct page
*page
,
1509 struct bio
*bio
= rq
->bio
;
1511 bio
->bi_io_vec
->bv_page
= page
;
1512 bio
->bi_io_vec
->bv_offset
= 0;
1513 bio
->bi_io_vec
->bv_len
= len
;
1515 bio
->bi_iter
.bi_size
= len
;
1517 bio
->bi_phys_segments
= 1;
1519 rq
->__data_len
= rq
->resid_len
= len
;
1520 rq
->nr_phys_segments
= 1;
1522 EXPORT_SYMBOL_GPL(blk_add_request_payload
);
1524 bool bio_attempt_back_merge(struct request_queue
*q
, struct request
*req
,
1527 const int ff
= bio
->bi_rw
& REQ_FAILFAST_MASK
;
1529 if (!ll_back_merge_fn(q
, req
, bio
))
1532 trace_block_bio_backmerge(q
, req
, bio
);
1534 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
1535 blk_rq_set_mixed_merge(req
);
1537 req
->biotail
->bi_next
= bio
;
1539 req
->__data_len
+= bio
->bi_iter
.bi_size
;
1540 req
->ioprio
= ioprio_best(req
->ioprio
, bio_prio(bio
));
1542 blk_account_io_start(req
, false);
1546 bool bio_attempt_front_merge(struct request_queue
*q
, struct request
*req
,
1549 const int ff
= bio
->bi_rw
& REQ_FAILFAST_MASK
;
1551 if (!ll_front_merge_fn(q
, req
, bio
))
1554 trace_block_bio_frontmerge(q
, req
, bio
);
1556 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
1557 blk_rq_set_mixed_merge(req
);
1559 bio
->bi_next
= req
->bio
;
1562 req
->__sector
= bio
->bi_iter
.bi_sector
;
1563 req
->__data_len
+= bio
->bi_iter
.bi_size
;
1564 req
->ioprio
= ioprio_best(req
->ioprio
, bio_prio(bio
));
1566 blk_account_io_start(req
, false);
1571 * blk_attempt_plug_merge - try to merge with %current's plugged list
1572 * @q: request_queue new bio is being queued at
1573 * @bio: new bio being queued
1574 * @request_count: out parameter for number of traversed plugged requests
1576 * Determine whether @bio being queued on @q can be merged with a request
1577 * on %current's plugged list. Returns %true if merge was successful,
1580 * Plugging coalesces IOs from the same issuer for the same purpose without
1581 * going through @q->queue_lock. As such it's more of an issuing mechanism
1582 * than scheduling, and the request, while may have elvpriv data, is not
1583 * added on the elevator at this point. In addition, we don't have
1584 * reliable access to the elevator outside queue lock. Only check basic
1585 * merging parameters without querying the elevator.
1587 * Caller must ensure !blk_queue_nomerges(q) beforehand.
1589 bool blk_attempt_plug_merge(struct request_queue
*q
, struct bio
*bio
,
1590 unsigned int *request_count
,
1591 struct request
**same_queue_rq
)
1593 struct blk_plug
*plug
;
1596 struct list_head
*plug_list
;
1598 plug
= current
->plug
;
1604 plug_list
= &plug
->mq_list
;
1606 plug_list
= &plug
->list
;
1608 list_for_each_entry_reverse(rq
, plug_list
, queuelist
) {
1614 * Only blk-mq multiple hardware queues case checks the
1615 * rq in the same queue, there should be only one such
1619 *same_queue_rq
= rq
;
1622 if (rq
->q
!= q
|| !blk_rq_merge_ok(rq
, bio
))
1625 el_ret
= blk_try_merge(rq
, bio
);
1626 if (el_ret
== ELEVATOR_BACK_MERGE
) {
1627 ret
= bio_attempt_back_merge(q
, rq
, bio
);
1630 } else if (el_ret
== ELEVATOR_FRONT_MERGE
) {
1631 ret
= bio_attempt_front_merge(q
, rq
, bio
);
1640 void init_request_from_bio(struct request
*req
, struct bio
*bio
)
1642 req
->cmd_type
= REQ_TYPE_FS
;
1644 req
->cmd_flags
|= bio
->bi_rw
& REQ_COMMON_MASK
;
1645 if (bio
->bi_rw
& REQ_RAHEAD
)
1646 req
->cmd_flags
|= REQ_FAILFAST_MASK
;
1649 req
->__sector
= bio
->bi_iter
.bi_sector
;
1650 req
->ioprio
= bio_prio(bio
);
1651 blk_rq_bio_prep(req
->q
, req
, bio
);
1654 static void blk_queue_bio(struct request_queue
*q
, struct bio
*bio
)
1656 const bool sync
= !!(bio
->bi_rw
& REQ_SYNC
);
1657 struct blk_plug
*plug
;
1658 int el_ret
, rw_flags
, where
= ELEVATOR_INSERT_SORT
;
1659 struct request
*req
;
1660 unsigned int request_count
= 0;
1662 blk_queue_split(q
, &bio
, q
->bio_split
);
1665 * low level driver can indicate that it wants pages above a
1666 * certain limit bounced to low memory (ie for highmem, or even
1667 * ISA dma in theory)
1669 blk_queue_bounce(q
, &bio
);
1671 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1672 bio
->bi_error
= -EIO
;
1677 if (bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
)) {
1678 spin_lock_irq(q
->queue_lock
);
1679 where
= ELEVATOR_INSERT_FLUSH
;
1684 * Check if we can merge with the plugged list before grabbing
1687 if (!blk_queue_nomerges(q
) &&
1688 blk_attempt_plug_merge(q
, bio
, &request_count
, NULL
))
1691 spin_lock_irq(q
->queue_lock
);
1693 el_ret
= elv_merge(q
, &req
, bio
);
1694 if (el_ret
== ELEVATOR_BACK_MERGE
) {
1695 if (bio_attempt_back_merge(q
, req
, bio
)) {
1696 elv_bio_merged(q
, req
, bio
);
1697 if (!attempt_back_merge(q
, req
))
1698 elv_merged_request(q
, req
, el_ret
);
1701 } else if (el_ret
== ELEVATOR_FRONT_MERGE
) {
1702 if (bio_attempt_front_merge(q
, req
, bio
)) {
1703 elv_bio_merged(q
, req
, bio
);
1704 if (!attempt_front_merge(q
, req
))
1705 elv_merged_request(q
, req
, el_ret
);
1712 * This sync check and mask will be re-done in init_request_from_bio(),
1713 * but we need to set it earlier to expose the sync flag to the
1714 * rq allocator and io schedulers.
1716 rw_flags
= bio_data_dir(bio
);
1718 rw_flags
|= REQ_SYNC
;
1721 * Grab a free request. This is might sleep but can not fail.
1722 * Returns with the queue unlocked.
1724 req
= get_request(q
, rw_flags
, bio
, GFP_NOIO
);
1726 bio
->bi_error
= PTR_ERR(req
);
1732 * After dropping the lock and possibly sleeping here, our request
1733 * may now be mergeable after it had proven unmergeable (above).
1734 * We don't worry about that case for efficiency. It won't happen
1735 * often, and the elevators are able to handle it.
1737 init_request_from_bio(req
, bio
);
1739 if (test_bit(QUEUE_FLAG_SAME_COMP
, &q
->queue_flags
))
1740 req
->cpu
= raw_smp_processor_id();
1742 plug
= current
->plug
;
1745 * If this is the first request added after a plug, fire
1749 trace_block_plug(q
);
1751 if (request_count
>= BLK_MAX_REQUEST_COUNT
) {
1752 blk_flush_plug_list(plug
, false);
1753 trace_block_plug(q
);
1756 list_add_tail(&req
->queuelist
, &plug
->list
);
1757 blk_account_io_start(req
, true);
1759 spin_lock_irq(q
->queue_lock
);
1760 add_acct_request(q
, req
, where
);
1763 spin_unlock_irq(q
->queue_lock
);
1768 * If bio->bi_dev is a partition, remap the location
1770 static inline void blk_partition_remap(struct bio
*bio
)
1772 struct block_device
*bdev
= bio
->bi_bdev
;
1774 if (bio_sectors(bio
) && bdev
!= bdev
->bd_contains
) {
1775 struct hd_struct
*p
= bdev
->bd_part
;
1777 bio
->bi_iter
.bi_sector
+= p
->start_sect
;
1778 bio
->bi_bdev
= bdev
->bd_contains
;
1780 trace_block_bio_remap(bdev_get_queue(bio
->bi_bdev
), bio
,
1782 bio
->bi_iter
.bi_sector
- p
->start_sect
);
1786 static void handle_bad_sector(struct bio
*bio
)
1788 char b
[BDEVNAME_SIZE
];
1790 printk(KERN_INFO
"attempt to access beyond end of device\n");
1791 printk(KERN_INFO
"%s: rw=%ld, want=%Lu, limit=%Lu\n",
1792 bdevname(bio
->bi_bdev
, b
),
1794 (unsigned long long)bio_end_sector(bio
),
1795 (long long)(i_size_read(bio
->bi_bdev
->bd_inode
) >> 9));
1798 #ifdef CONFIG_FAIL_MAKE_REQUEST
1800 static DECLARE_FAULT_ATTR(fail_make_request
);
1802 static int __init
setup_fail_make_request(char *str
)
1804 return setup_fault_attr(&fail_make_request
, str
);
1806 __setup("fail_make_request=", setup_fail_make_request
);
1808 static bool should_fail_request(struct hd_struct
*part
, unsigned int bytes
)
1810 return part
->make_it_fail
&& should_fail(&fail_make_request
, bytes
);
1813 static int __init
fail_make_request_debugfs(void)
1815 struct dentry
*dir
= fault_create_debugfs_attr("fail_make_request",
1816 NULL
, &fail_make_request
);
1818 return PTR_ERR_OR_ZERO(dir
);
1821 late_initcall(fail_make_request_debugfs
);
1823 #else /* CONFIG_FAIL_MAKE_REQUEST */
1825 static inline bool should_fail_request(struct hd_struct
*part
,
1831 #endif /* CONFIG_FAIL_MAKE_REQUEST */
1834 * Check whether this bio extends beyond the end of the device.
1836 static inline int bio_check_eod(struct bio
*bio
, unsigned int nr_sectors
)
1843 /* Test device or partition size, when known. */
1844 maxsector
= i_size_read(bio
->bi_bdev
->bd_inode
) >> 9;
1846 sector_t sector
= bio
->bi_iter
.bi_sector
;
1848 if (maxsector
< nr_sectors
|| maxsector
- nr_sectors
< sector
) {
1850 * This may well happen - the kernel calls bread()
1851 * without checking the size of the device, e.g., when
1852 * mounting a device.
1854 handle_bad_sector(bio
);
1862 static noinline_for_stack
bool
1863 generic_make_request_checks(struct bio
*bio
)
1865 struct request_queue
*q
;
1866 int nr_sectors
= bio_sectors(bio
);
1868 char b
[BDEVNAME_SIZE
];
1869 struct hd_struct
*part
;
1873 if (bio_check_eod(bio
, nr_sectors
))
1876 q
= bdev_get_queue(bio
->bi_bdev
);
1879 "generic_make_request: Trying to access "
1880 "nonexistent block-device %s (%Lu)\n",
1881 bdevname(bio
->bi_bdev
, b
),
1882 (long long) bio
->bi_iter
.bi_sector
);
1886 part
= bio
->bi_bdev
->bd_part
;
1887 if (should_fail_request(part
, bio
->bi_iter
.bi_size
) ||
1888 should_fail_request(&part_to_disk(part
)->part0
,
1889 bio
->bi_iter
.bi_size
))
1893 * If this device has partitions, remap block n
1894 * of partition p to block n+start(p) of the disk.
1896 blk_partition_remap(bio
);
1898 if (bio_check_eod(bio
, nr_sectors
))
1902 * Filter flush bio's early so that make_request based
1903 * drivers without flush support don't have to worry
1906 if ((bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
)) && !q
->flush_flags
) {
1907 bio
->bi_rw
&= ~(REQ_FLUSH
| REQ_FUA
);
1914 if ((bio
->bi_rw
& REQ_DISCARD
) &&
1915 (!blk_queue_discard(q
) ||
1916 ((bio
->bi_rw
& REQ_SECURE
) && !blk_queue_secdiscard(q
)))) {
1921 if (bio
->bi_rw
& REQ_WRITE_SAME
&& !bdev_write_same(bio
->bi_bdev
)) {
1927 * Various block parts want %current->io_context and lazy ioc
1928 * allocation ends up trading a lot of pain for a small amount of
1929 * memory. Just allocate it upfront. This may fail and block
1930 * layer knows how to live with it.
1932 create_io_context(GFP_ATOMIC
, q
->node
);
1934 if (!blkcg_bio_issue_check(q
, bio
))
1937 trace_block_bio_queue(q
, bio
);
1941 bio
->bi_error
= err
;
1947 * generic_make_request - hand a buffer to its device driver for I/O
1948 * @bio: The bio describing the location in memory and on the device.
1950 * generic_make_request() is used to make I/O requests of block
1951 * devices. It is passed a &struct bio, which describes the I/O that needs
1954 * generic_make_request() does not return any status. The
1955 * success/failure status of the request, along with notification of
1956 * completion, is delivered asynchronously through the bio->bi_end_io
1957 * function described (one day) else where.
1959 * The caller of generic_make_request must make sure that bi_io_vec
1960 * are set to describe the memory buffer, and that bi_dev and bi_sector are
1961 * set to describe the device address, and the
1962 * bi_end_io and optionally bi_private are set to describe how
1963 * completion notification should be signaled.
1965 * generic_make_request and the drivers it calls may use bi_next if this
1966 * bio happens to be merged with someone else, and may resubmit the bio to
1967 * a lower device by calling into generic_make_request recursively, which
1968 * means the bio should NOT be touched after the call to ->make_request_fn.
1970 void generic_make_request(struct bio
*bio
)
1972 struct bio_list bio_list_on_stack
;
1974 if (!generic_make_request_checks(bio
))
1978 * We only want one ->make_request_fn to be active at a time, else
1979 * stack usage with stacked devices could be a problem. So use
1980 * current->bio_list to keep a list of requests submited by a
1981 * make_request_fn function. current->bio_list is also used as a
1982 * flag to say if generic_make_request is currently active in this
1983 * task or not. If it is NULL, then no make_request is active. If
1984 * it is non-NULL, then a make_request is active, and new requests
1985 * should be added at the tail
1987 if (current
->bio_list
) {
1988 bio_list_add(current
->bio_list
, bio
);
1992 /* following loop may be a bit non-obvious, and so deserves some
1994 * Before entering the loop, bio->bi_next is NULL (as all callers
1995 * ensure that) so we have a list with a single bio.
1996 * We pretend that we have just taken it off a longer list, so
1997 * we assign bio_list to a pointer to the bio_list_on_stack,
1998 * thus initialising the bio_list of new bios to be
1999 * added. ->make_request() may indeed add some more bios
2000 * through a recursive call to generic_make_request. If it
2001 * did, we find a non-NULL value in bio_list and re-enter the loop
2002 * from the top. In this case we really did just take the bio
2003 * of the top of the list (no pretending) and so remove it from
2004 * bio_list, and call into ->make_request() again.
2006 BUG_ON(bio
->bi_next
);
2007 bio_list_init(&bio_list_on_stack
);
2008 current
->bio_list
= &bio_list_on_stack
;
2010 struct request_queue
*q
= bdev_get_queue(bio
->bi_bdev
);
2012 if (likely(blk_queue_enter(q
, __GFP_WAIT
) == 0)) {
2014 q
->make_request_fn(q
, bio
);
2018 bio
= bio_list_pop(current
->bio_list
);
2020 struct bio
*bio_next
= bio_list_pop(current
->bio_list
);
2026 current
->bio_list
= NULL
; /* deactivate */
2028 EXPORT_SYMBOL(generic_make_request
);
2031 * submit_bio - submit a bio to the block device layer for I/O
2032 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
2033 * @bio: The &struct bio which describes the I/O
2035 * submit_bio() is very similar in purpose to generic_make_request(), and
2036 * uses that function to do most of the work. Both are fairly rough
2037 * interfaces; @bio must be presetup and ready for I/O.
2040 void submit_bio(int rw
, struct bio
*bio
)
2045 * If it's a regular read/write or a barrier with data attached,
2046 * go through the normal accounting stuff before submission.
2048 if (bio_has_data(bio
)) {
2051 if (unlikely(rw
& REQ_WRITE_SAME
))
2052 count
= bdev_logical_block_size(bio
->bi_bdev
) >> 9;
2054 count
= bio_sectors(bio
);
2057 count_vm_events(PGPGOUT
, count
);
2059 task_io_account_read(bio
->bi_iter
.bi_size
);
2060 count_vm_events(PGPGIN
, count
);
2063 if (unlikely(block_dump
)) {
2064 char b
[BDEVNAME_SIZE
];
2065 printk(KERN_DEBUG
"%s(%d): %s block %Lu on %s (%u sectors)\n",
2066 current
->comm
, task_pid_nr(current
),
2067 (rw
& WRITE
) ? "WRITE" : "READ",
2068 (unsigned long long)bio
->bi_iter
.bi_sector
,
2069 bdevname(bio
->bi_bdev
, b
),
2074 generic_make_request(bio
);
2076 EXPORT_SYMBOL(submit_bio
);
2079 * blk_rq_check_limits - Helper function to check a request for the queue limit
2081 * @rq: the request being checked
2084 * @rq may have been made based on weaker limitations of upper-level queues
2085 * in request stacking drivers, and it may violate the limitation of @q.
2086 * Since the block layer and the underlying device driver trust @rq
2087 * after it is inserted to @q, it should be checked against @q before
2088 * the insertion using this generic function.
2090 * This function should also be useful for request stacking drivers
2091 * in some cases below, so export this function.
2092 * Request stacking drivers like request-based dm may change the queue
2093 * limits while requests are in the queue (e.g. dm's table swapping).
2094 * Such request stacking drivers should check those requests against
2095 * the new queue limits again when they dispatch those requests,
2096 * although such checkings are also done against the old queue limits
2097 * when submitting requests.
2099 int blk_rq_check_limits(struct request_queue
*q
, struct request
*rq
)
2101 if (!rq_mergeable(rq
))
2104 if (blk_rq_sectors(rq
) > blk_queue_get_max_sectors(q
, rq
->cmd_flags
)) {
2105 printk(KERN_ERR
"%s: over max size limit.\n", __func__
);
2110 * queue's settings related to segment counting like q->bounce_pfn
2111 * may differ from that of other stacking queues.
2112 * Recalculate it to check the request correctly on this queue's
2115 blk_recalc_rq_segments(rq
);
2116 if (rq
->nr_phys_segments
> queue_max_segments(q
)) {
2117 printk(KERN_ERR
"%s: over max segments limit.\n", __func__
);
2123 EXPORT_SYMBOL_GPL(blk_rq_check_limits
);
2126 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
2127 * @q: the queue to submit the request
2128 * @rq: the request being queued
2130 int blk_insert_cloned_request(struct request_queue
*q
, struct request
*rq
)
2132 unsigned long flags
;
2133 int where
= ELEVATOR_INSERT_BACK
;
2135 if (blk_rq_check_limits(q
, rq
))
2139 should_fail_request(&rq
->rq_disk
->part0
, blk_rq_bytes(rq
)))
2143 if (blk_queue_io_stat(q
))
2144 blk_account_io_start(rq
, true);
2145 blk_mq_insert_request(rq
, false, true, true);
2149 spin_lock_irqsave(q
->queue_lock
, flags
);
2150 if (unlikely(blk_queue_dying(q
))) {
2151 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2156 * Submitting request must be dequeued before calling this function
2157 * because it will be linked to another request_queue
2159 BUG_ON(blk_queued_rq(rq
));
2161 if (rq
->cmd_flags
& (REQ_FLUSH
|REQ_FUA
))
2162 where
= ELEVATOR_INSERT_FLUSH
;
2164 add_acct_request(q
, rq
, where
);
2165 if (where
== ELEVATOR_INSERT_FLUSH
)
2167 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2171 EXPORT_SYMBOL_GPL(blk_insert_cloned_request
);
2174 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
2175 * @rq: request to examine
2178 * A request could be merge of IOs which require different failure
2179 * handling. This function determines the number of bytes which
2180 * can be failed from the beginning of the request without
2181 * crossing into area which need to be retried further.
2184 * The number of bytes to fail.
2187 * queue_lock must be held.
2189 unsigned int blk_rq_err_bytes(const struct request
*rq
)
2191 unsigned int ff
= rq
->cmd_flags
& REQ_FAILFAST_MASK
;
2192 unsigned int bytes
= 0;
2195 if (!(rq
->cmd_flags
& REQ_MIXED_MERGE
))
2196 return blk_rq_bytes(rq
);
2199 * Currently the only 'mixing' which can happen is between
2200 * different fastfail types. We can safely fail portions
2201 * which have all the failfast bits that the first one has -
2202 * the ones which are at least as eager to fail as the first
2205 for (bio
= rq
->bio
; bio
; bio
= bio
->bi_next
) {
2206 if ((bio
->bi_rw
& ff
) != ff
)
2208 bytes
+= bio
->bi_iter
.bi_size
;
2211 /* this could lead to infinite loop */
2212 BUG_ON(blk_rq_bytes(rq
) && !bytes
);
2215 EXPORT_SYMBOL_GPL(blk_rq_err_bytes
);
2217 void blk_account_io_completion(struct request
*req
, unsigned int bytes
)
2219 if (blk_do_io_stat(req
)) {
2220 const int rw
= rq_data_dir(req
);
2221 struct hd_struct
*part
;
2224 cpu
= part_stat_lock();
2226 part_stat_add(cpu
, part
, sectors
[rw
], bytes
>> 9);
2231 void blk_account_io_done(struct request
*req
)
2234 * Account IO completion. flush_rq isn't accounted as a
2235 * normal IO on queueing nor completion. Accounting the
2236 * containing request is enough.
2238 if (blk_do_io_stat(req
) && !(req
->cmd_flags
& REQ_FLUSH_SEQ
)) {
2239 unsigned long duration
= jiffies
- req
->start_time
;
2240 const int rw
= rq_data_dir(req
);
2241 struct hd_struct
*part
;
2244 cpu
= part_stat_lock();
2247 part_stat_inc(cpu
, part
, ios
[rw
]);
2248 part_stat_add(cpu
, part
, ticks
[rw
], duration
);
2249 part_round_stats(cpu
, part
);
2250 part_dec_in_flight(part
, rw
);
2252 hd_struct_put(part
);
2259 * Don't process normal requests when queue is suspended
2260 * or in the process of suspending/resuming
2262 static struct request
*blk_pm_peek_request(struct request_queue
*q
,
2265 if (q
->dev
&& (q
->rpm_status
== RPM_SUSPENDED
||
2266 (q
->rpm_status
!= RPM_ACTIVE
&& !(rq
->cmd_flags
& REQ_PM
))))
2272 static inline struct request
*blk_pm_peek_request(struct request_queue
*q
,
2279 void blk_account_io_start(struct request
*rq
, bool new_io
)
2281 struct hd_struct
*part
;
2282 int rw
= rq_data_dir(rq
);
2285 if (!blk_do_io_stat(rq
))
2288 cpu
= part_stat_lock();
2292 part_stat_inc(cpu
, part
, merges
[rw
]);
2294 part
= disk_map_sector_rcu(rq
->rq_disk
, blk_rq_pos(rq
));
2295 if (!hd_struct_try_get(part
)) {
2297 * The partition is already being removed,
2298 * the request will be accounted on the disk only
2300 * We take a reference on disk->part0 although that
2301 * partition will never be deleted, so we can treat
2302 * it as any other partition.
2304 part
= &rq
->rq_disk
->part0
;
2305 hd_struct_get(part
);
2307 part_round_stats(cpu
, part
);
2308 part_inc_in_flight(part
, rw
);
2316 * blk_peek_request - peek at the top of a request queue
2317 * @q: request queue to peek at
2320 * Return the request at the top of @q. The returned request
2321 * should be started using blk_start_request() before LLD starts
2325 * Pointer to the request at the top of @q if available. Null
2329 * queue_lock must be held.
2331 struct request
*blk_peek_request(struct request_queue
*q
)
2336 while ((rq
= __elv_next_request(q
)) != NULL
) {
2338 rq
= blk_pm_peek_request(q
, rq
);
2342 if (!(rq
->cmd_flags
& REQ_STARTED
)) {
2344 * This is the first time the device driver
2345 * sees this request (possibly after
2346 * requeueing). Notify IO scheduler.
2348 if (rq
->cmd_flags
& REQ_SORTED
)
2349 elv_activate_rq(q
, rq
);
2352 * just mark as started even if we don't start
2353 * it, a request that has been delayed should
2354 * not be passed by new incoming requests
2356 rq
->cmd_flags
|= REQ_STARTED
;
2357 trace_block_rq_issue(q
, rq
);
2360 if (!q
->boundary_rq
|| q
->boundary_rq
== rq
) {
2361 q
->end_sector
= rq_end_sector(rq
);
2362 q
->boundary_rq
= NULL
;
2365 if (rq
->cmd_flags
& REQ_DONTPREP
)
2368 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
2370 * make sure space for the drain appears we
2371 * know we can do this because max_hw_segments
2372 * has been adjusted to be one fewer than the
2375 rq
->nr_phys_segments
++;
2381 ret
= q
->prep_rq_fn(q
, rq
);
2382 if (ret
== BLKPREP_OK
) {
2384 } else if (ret
== BLKPREP_DEFER
) {
2386 * the request may have been (partially) prepped.
2387 * we need to keep this request in the front to
2388 * avoid resource deadlock. REQ_STARTED will
2389 * prevent other fs requests from passing this one.
2391 if (q
->dma_drain_size
&& blk_rq_bytes(rq
) &&
2392 !(rq
->cmd_flags
& REQ_DONTPREP
)) {
2394 * remove the space for the drain we added
2395 * so that we don't add it again
2397 --rq
->nr_phys_segments
;
2402 } else if (ret
== BLKPREP_KILL
) {
2403 rq
->cmd_flags
|= REQ_QUIET
;
2405 * Mark this request as started so we don't trigger
2406 * any debug logic in the end I/O path.
2408 blk_start_request(rq
);
2409 __blk_end_request_all(rq
, -EIO
);
2411 printk(KERN_ERR
"%s: bad return=%d\n", __func__
, ret
);
2418 EXPORT_SYMBOL(blk_peek_request
);
2420 void blk_dequeue_request(struct request
*rq
)
2422 struct request_queue
*q
= rq
->q
;
2424 BUG_ON(list_empty(&rq
->queuelist
));
2425 BUG_ON(ELV_ON_HASH(rq
));
2427 list_del_init(&rq
->queuelist
);
2430 * the time frame between a request being removed from the lists
2431 * and to it is freed is accounted as io that is in progress at
2434 if (blk_account_rq(rq
)) {
2435 q
->in_flight
[rq_is_sync(rq
)]++;
2436 set_io_start_time_ns(rq
);
2441 * blk_start_request - start request processing on the driver
2442 * @req: request to dequeue
2445 * Dequeue @req and start timeout timer on it. This hands off the
2446 * request to the driver.
2448 * Block internal functions which don't want to start timer should
2449 * call blk_dequeue_request().
2452 * queue_lock must be held.
2454 void blk_start_request(struct request
*req
)
2456 blk_dequeue_request(req
);
2459 * We are now handing the request to the hardware, initialize
2460 * resid_len to full count and add the timeout handler.
2462 req
->resid_len
= blk_rq_bytes(req
);
2463 if (unlikely(blk_bidi_rq(req
)))
2464 req
->next_rq
->resid_len
= blk_rq_bytes(req
->next_rq
);
2466 BUG_ON(test_bit(REQ_ATOM_COMPLETE
, &req
->atomic_flags
));
2469 EXPORT_SYMBOL(blk_start_request
);
2472 * blk_fetch_request - fetch a request from a request queue
2473 * @q: request queue to fetch a request from
2476 * Return the request at the top of @q. The request is started on
2477 * return and LLD can start processing it immediately.
2480 * Pointer to the request at the top of @q if available. Null
2484 * queue_lock must be held.
2486 struct request
*blk_fetch_request(struct request_queue
*q
)
2490 rq
= blk_peek_request(q
);
2492 blk_start_request(rq
);
2495 EXPORT_SYMBOL(blk_fetch_request
);
2498 * blk_update_request - Special helper function for request stacking drivers
2499 * @req: the request being processed
2500 * @error: %0 for success, < %0 for error
2501 * @nr_bytes: number of bytes to complete @req
2504 * Ends I/O on a number of bytes attached to @req, but doesn't complete
2505 * the request structure even if @req doesn't have leftover.
2506 * If @req has leftover, sets it up for the next range of segments.
2508 * This special helper function is only for request stacking drivers
2509 * (e.g. request-based dm) so that they can handle partial completion.
2510 * Actual device drivers should use blk_end_request instead.
2512 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
2513 * %false return from this function.
2516 * %false - this request doesn't have any more data
2517 * %true - this request has more data
2519 bool blk_update_request(struct request
*req
, int error
, unsigned int nr_bytes
)
2523 trace_block_rq_complete(req
->q
, req
, nr_bytes
);
2529 * For fs requests, rq is just carrier of independent bio's
2530 * and each partial completion should be handled separately.
2531 * Reset per-request error on each partial completion.
2533 * TODO: tj: This is too subtle. It would be better to let
2534 * low level drivers do what they see fit.
2536 if (req
->cmd_type
== REQ_TYPE_FS
)
2539 if (error
&& req
->cmd_type
== REQ_TYPE_FS
&&
2540 !(req
->cmd_flags
& REQ_QUIET
)) {
2545 error_type
= "recoverable transport";
2548 error_type
= "critical target";
2551 error_type
= "critical nexus";
2554 error_type
= "timeout";
2557 error_type
= "critical space allocation";
2560 error_type
= "critical medium";
2567 printk_ratelimited(KERN_ERR
"%s: %s error, dev %s, sector %llu\n",
2568 __func__
, error_type
, req
->rq_disk
?
2569 req
->rq_disk
->disk_name
: "?",
2570 (unsigned long long)blk_rq_pos(req
));
2574 blk_account_io_completion(req
, nr_bytes
);
2578 struct bio
*bio
= req
->bio
;
2579 unsigned bio_bytes
= min(bio
->bi_iter
.bi_size
, nr_bytes
);
2581 if (bio_bytes
== bio
->bi_iter
.bi_size
)
2582 req
->bio
= bio
->bi_next
;
2584 req_bio_endio(req
, bio
, bio_bytes
, error
);
2586 total_bytes
+= bio_bytes
;
2587 nr_bytes
-= bio_bytes
;
2598 * Reset counters so that the request stacking driver
2599 * can find how many bytes remain in the request
2602 req
->__data_len
= 0;
2606 req
->__data_len
-= total_bytes
;
2608 /* update sector only for requests with clear definition of sector */
2609 if (req
->cmd_type
== REQ_TYPE_FS
)
2610 req
->__sector
+= total_bytes
>> 9;
2612 /* mixed attributes always follow the first bio */
2613 if (req
->cmd_flags
& REQ_MIXED_MERGE
) {
2614 req
->cmd_flags
&= ~REQ_FAILFAST_MASK
;
2615 req
->cmd_flags
|= req
->bio
->bi_rw
& REQ_FAILFAST_MASK
;
2619 * If total number of sectors is less than the first segment
2620 * size, something has gone terribly wrong.
2622 if (blk_rq_bytes(req
) < blk_rq_cur_bytes(req
)) {
2623 blk_dump_rq_flags(req
, "request botched");
2624 req
->__data_len
= blk_rq_cur_bytes(req
);
2627 /* recalculate the number of segments */
2628 blk_recalc_rq_segments(req
);
2632 EXPORT_SYMBOL_GPL(blk_update_request
);
2634 static bool blk_update_bidi_request(struct request
*rq
, int error
,
2635 unsigned int nr_bytes
,
2636 unsigned int bidi_bytes
)
2638 if (blk_update_request(rq
, error
, nr_bytes
))
2641 /* Bidi request must be completed as a whole */
2642 if (unlikely(blk_bidi_rq(rq
)) &&
2643 blk_update_request(rq
->next_rq
, error
, bidi_bytes
))
2646 if (blk_queue_add_random(rq
->q
))
2647 add_disk_randomness(rq
->rq_disk
);
2653 * blk_unprep_request - unprepare a request
2656 * This function makes a request ready for complete resubmission (or
2657 * completion). It happens only after all error handling is complete,
2658 * so represents the appropriate moment to deallocate any resources
2659 * that were allocated to the request in the prep_rq_fn. The queue
2660 * lock is held when calling this.
2662 void blk_unprep_request(struct request
*req
)
2664 struct request_queue
*q
= req
->q
;
2666 req
->cmd_flags
&= ~REQ_DONTPREP
;
2667 if (q
->unprep_rq_fn
)
2668 q
->unprep_rq_fn(q
, req
);
2670 EXPORT_SYMBOL_GPL(blk_unprep_request
);
2673 * queue lock must be held
2675 void blk_finish_request(struct request
*req
, int error
)
2677 if (req
->cmd_flags
& REQ_QUEUED
)
2678 blk_queue_end_tag(req
->q
, req
);
2680 BUG_ON(blk_queued_rq(req
));
2682 if (unlikely(laptop_mode
) && req
->cmd_type
== REQ_TYPE_FS
)
2683 laptop_io_completion(&req
->q
->backing_dev_info
);
2685 blk_delete_timer(req
);
2687 if (req
->cmd_flags
& REQ_DONTPREP
)
2688 blk_unprep_request(req
);
2690 blk_account_io_done(req
);
2693 req
->end_io(req
, error
);
2695 if (blk_bidi_rq(req
))
2696 __blk_put_request(req
->next_rq
->q
, req
->next_rq
);
2698 __blk_put_request(req
->q
, req
);
2701 EXPORT_SYMBOL(blk_finish_request
);
2704 * blk_end_bidi_request - Complete a bidi request
2705 * @rq: the request to complete
2706 * @error: %0 for success, < %0 for error
2707 * @nr_bytes: number of bytes to complete @rq
2708 * @bidi_bytes: number of bytes to complete @rq->next_rq
2711 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2712 * Drivers that supports bidi can safely call this member for any
2713 * type of request, bidi or uni. In the later case @bidi_bytes is
2717 * %false - we are done with this request
2718 * %true - still buffers pending for this request
2720 static bool blk_end_bidi_request(struct request
*rq
, int error
,
2721 unsigned int nr_bytes
, unsigned int bidi_bytes
)
2723 struct request_queue
*q
= rq
->q
;
2724 unsigned long flags
;
2726 if (blk_update_bidi_request(rq
, error
, nr_bytes
, bidi_bytes
))
2729 spin_lock_irqsave(q
->queue_lock
, flags
);
2730 blk_finish_request(rq
, error
);
2731 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2737 * __blk_end_bidi_request - Complete a bidi request with queue lock held
2738 * @rq: the request to complete
2739 * @error: %0 for success, < %0 for error
2740 * @nr_bytes: number of bytes to complete @rq
2741 * @bidi_bytes: number of bytes to complete @rq->next_rq
2744 * Identical to blk_end_bidi_request() except that queue lock is
2745 * assumed to be locked on entry and remains so on return.
2748 * %false - we are done with this request
2749 * %true - still buffers pending for this request
2751 bool __blk_end_bidi_request(struct request
*rq
, int error
,
2752 unsigned int nr_bytes
, unsigned int bidi_bytes
)
2754 if (blk_update_bidi_request(rq
, error
, nr_bytes
, bidi_bytes
))
2757 blk_finish_request(rq
, error
);
2763 * blk_end_request - Helper function for drivers to complete the request.
2764 * @rq: the request being processed
2765 * @error: %0 for success, < %0 for error
2766 * @nr_bytes: number of bytes to complete
2769 * Ends I/O on a number of bytes attached to @rq.
2770 * If @rq has leftover, sets it up for the next range of segments.
2773 * %false - we are done with this request
2774 * %true - still buffers pending for this request
2776 bool blk_end_request(struct request
*rq
, int error
, unsigned int nr_bytes
)
2778 return blk_end_bidi_request(rq
, error
, nr_bytes
, 0);
2780 EXPORT_SYMBOL(blk_end_request
);
2783 * blk_end_request_all - Helper function for drives to finish the request.
2784 * @rq: the request to finish
2785 * @error: %0 for success, < %0 for error
2788 * Completely finish @rq.
2790 void blk_end_request_all(struct request
*rq
, int error
)
2793 unsigned int bidi_bytes
= 0;
2795 if (unlikely(blk_bidi_rq(rq
)))
2796 bidi_bytes
= blk_rq_bytes(rq
->next_rq
);
2798 pending
= blk_end_bidi_request(rq
, error
, blk_rq_bytes(rq
), bidi_bytes
);
2801 EXPORT_SYMBOL(blk_end_request_all
);
2804 * blk_end_request_cur - Helper function to finish the current request chunk.
2805 * @rq: the request to finish the current chunk for
2806 * @error: %0 for success, < %0 for error
2809 * Complete the current consecutively mapped chunk from @rq.
2812 * %false - we are done with this request
2813 * %true - still buffers pending for this request
2815 bool blk_end_request_cur(struct request
*rq
, int error
)
2817 return blk_end_request(rq
, error
, blk_rq_cur_bytes(rq
));
2819 EXPORT_SYMBOL(blk_end_request_cur
);
2822 * blk_end_request_err - Finish a request till the next failure boundary.
2823 * @rq: the request to finish till the next failure boundary for
2824 * @error: must be negative errno
2827 * Complete @rq till the next failure boundary.
2830 * %false - we are done with this request
2831 * %true - still buffers pending for this request
2833 bool blk_end_request_err(struct request
*rq
, int error
)
2835 WARN_ON(error
>= 0);
2836 return blk_end_request(rq
, error
, blk_rq_err_bytes(rq
));
2838 EXPORT_SYMBOL_GPL(blk_end_request_err
);
2841 * __blk_end_request - Helper function for drivers to complete the request.
2842 * @rq: the request being processed
2843 * @error: %0 for success, < %0 for error
2844 * @nr_bytes: number of bytes to complete
2847 * Must be called with queue lock held unlike blk_end_request().
2850 * %false - we are done with this request
2851 * %true - still buffers pending for this request
2853 bool __blk_end_request(struct request
*rq
, int error
, unsigned int nr_bytes
)
2855 return __blk_end_bidi_request(rq
, error
, nr_bytes
, 0);
2857 EXPORT_SYMBOL(__blk_end_request
);
2860 * __blk_end_request_all - Helper function for drives to finish the request.
2861 * @rq: the request to finish
2862 * @error: %0 for success, < %0 for error
2865 * Completely finish @rq. Must be called with queue lock held.
2867 void __blk_end_request_all(struct request
*rq
, int error
)
2870 unsigned int bidi_bytes
= 0;
2872 if (unlikely(blk_bidi_rq(rq
)))
2873 bidi_bytes
= blk_rq_bytes(rq
->next_rq
);
2875 pending
= __blk_end_bidi_request(rq
, error
, blk_rq_bytes(rq
), bidi_bytes
);
2878 EXPORT_SYMBOL(__blk_end_request_all
);
2881 * __blk_end_request_cur - Helper function to finish the current request chunk.
2882 * @rq: the request to finish the current chunk for
2883 * @error: %0 for success, < %0 for error
2886 * Complete the current consecutively mapped chunk from @rq. Must
2887 * be called with queue lock held.
2890 * %false - we are done with this request
2891 * %true - still buffers pending for this request
2893 bool __blk_end_request_cur(struct request
*rq
, int error
)
2895 return __blk_end_request(rq
, error
, blk_rq_cur_bytes(rq
));
2897 EXPORT_SYMBOL(__blk_end_request_cur
);
2900 * __blk_end_request_err - Finish a request till the next failure boundary.
2901 * @rq: the request to finish till the next failure boundary for
2902 * @error: must be negative errno
2905 * Complete @rq till the next failure boundary. Must be called
2906 * with queue lock held.
2909 * %false - we are done with this request
2910 * %true - still buffers pending for this request
2912 bool __blk_end_request_err(struct request
*rq
, int error
)
2914 WARN_ON(error
>= 0);
2915 return __blk_end_request(rq
, error
, blk_rq_err_bytes(rq
));
2917 EXPORT_SYMBOL_GPL(__blk_end_request_err
);
2919 void blk_rq_bio_prep(struct request_queue
*q
, struct request
*rq
,
2922 /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */
2923 rq
->cmd_flags
|= bio
->bi_rw
& REQ_WRITE
;
2925 if (bio_has_data(bio
))
2926 rq
->nr_phys_segments
= bio_phys_segments(q
, bio
);
2928 rq
->__data_len
= bio
->bi_iter
.bi_size
;
2929 rq
->bio
= rq
->biotail
= bio
;
2932 rq
->rq_disk
= bio
->bi_bdev
->bd_disk
;
2935 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
2937 * rq_flush_dcache_pages - Helper function to flush all pages in a request
2938 * @rq: the request to be flushed
2941 * Flush all pages in @rq.
2943 void rq_flush_dcache_pages(struct request
*rq
)
2945 struct req_iterator iter
;
2946 struct bio_vec bvec
;
2948 rq_for_each_segment(bvec
, rq
, iter
)
2949 flush_dcache_page(bvec
.bv_page
);
2951 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages
);
2955 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
2956 * @q : the queue of the device being checked
2959 * Check if underlying low-level drivers of a device are busy.
2960 * If the drivers want to export their busy state, they must set own
2961 * exporting function using blk_queue_lld_busy() first.
2963 * Basically, this function is used only by request stacking drivers
2964 * to stop dispatching requests to underlying devices when underlying
2965 * devices are busy. This behavior helps more I/O merging on the queue
2966 * of the request stacking driver and prevents I/O throughput regression
2967 * on burst I/O load.
2970 * 0 - Not busy (The request stacking driver should dispatch request)
2971 * 1 - Busy (The request stacking driver should stop dispatching request)
2973 int blk_lld_busy(struct request_queue
*q
)
2976 return q
->lld_busy_fn(q
);
2980 EXPORT_SYMBOL_GPL(blk_lld_busy
);
2983 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
2984 * @rq: the clone request to be cleaned up
2987 * Free all bios in @rq for a cloned request.
2989 void blk_rq_unprep_clone(struct request
*rq
)
2993 while ((bio
= rq
->bio
) != NULL
) {
2994 rq
->bio
= bio
->bi_next
;
2999 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone
);
3002 * Copy attributes of the original request to the clone request.
3003 * The actual data parts (e.g. ->cmd, ->sense) are not copied.
3005 static void __blk_rq_prep_clone(struct request
*dst
, struct request
*src
)
3007 dst
->cpu
= src
->cpu
;
3008 dst
->cmd_flags
|= (src
->cmd_flags
& REQ_CLONE_MASK
) | REQ_NOMERGE
;
3009 dst
->cmd_type
= src
->cmd_type
;
3010 dst
->__sector
= blk_rq_pos(src
);
3011 dst
->__data_len
= blk_rq_bytes(src
);
3012 dst
->nr_phys_segments
= src
->nr_phys_segments
;
3013 dst
->ioprio
= src
->ioprio
;
3014 dst
->extra_len
= src
->extra_len
;
3018 * blk_rq_prep_clone - Helper function to setup clone request
3019 * @rq: the request to be setup
3020 * @rq_src: original request to be cloned
3021 * @bs: bio_set that bios for clone are allocated from
3022 * @gfp_mask: memory allocation mask for bio
3023 * @bio_ctr: setup function to be called for each clone bio.
3024 * Returns %0 for success, non %0 for failure.
3025 * @data: private data to be passed to @bio_ctr
3028 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
3029 * The actual data parts of @rq_src (e.g. ->cmd, ->sense)
3030 * are not copied, and copying such parts is the caller's responsibility.
3031 * Also, pages which the original bios are pointing to are not copied
3032 * and the cloned bios just point same pages.
3033 * So cloned bios must be completed before original bios, which means
3034 * the caller must complete @rq before @rq_src.
3036 int blk_rq_prep_clone(struct request
*rq
, struct request
*rq_src
,
3037 struct bio_set
*bs
, gfp_t gfp_mask
,
3038 int (*bio_ctr
)(struct bio
*, struct bio
*, void *),
3041 struct bio
*bio
, *bio_src
;
3046 __rq_for_each_bio(bio_src
, rq_src
) {
3047 bio
= bio_clone_fast(bio_src
, gfp_mask
, bs
);
3051 if (bio_ctr
&& bio_ctr(bio
, bio_src
, data
))
3055 rq
->biotail
->bi_next
= bio
;
3058 rq
->bio
= rq
->biotail
= bio
;
3061 __blk_rq_prep_clone(rq
, rq_src
);
3068 blk_rq_unprep_clone(rq
);
3072 EXPORT_SYMBOL_GPL(blk_rq_prep_clone
);
3074 int kblockd_schedule_work(struct work_struct
*work
)
3076 return queue_work(kblockd_workqueue
, work
);
3078 EXPORT_SYMBOL(kblockd_schedule_work
);
3080 int kblockd_schedule_delayed_work(struct delayed_work
*dwork
,
3081 unsigned long delay
)
3083 return queue_delayed_work(kblockd_workqueue
, dwork
, delay
);
3085 EXPORT_SYMBOL(kblockd_schedule_delayed_work
);
3087 int kblockd_schedule_delayed_work_on(int cpu
, struct delayed_work
*dwork
,
3088 unsigned long delay
)
3090 return queue_delayed_work_on(cpu
, kblockd_workqueue
, dwork
, delay
);
3092 EXPORT_SYMBOL(kblockd_schedule_delayed_work_on
);
3095 * blk_start_plug - initialize blk_plug and track it inside the task_struct
3096 * @plug: The &struct blk_plug that needs to be initialized
3099 * Tracking blk_plug inside the task_struct will help with auto-flushing the
3100 * pending I/O should the task end up blocking between blk_start_plug() and
3101 * blk_finish_plug(). This is important from a performance perspective, but
3102 * also ensures that we don't deadlock. For instance, if the task is blocking
3103 * for a memory allocation, memory reclaim could end up wanting to free a
3104 * page belonging to that request that is currently residing in our private
3105 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
3106 * this kind of deadlock.
3108 void blk_start_plug(struct blk_plug
*plug
)
3110 struct task_struct
*tsk
= current
;
3113 * If this is a nested plug, don't actually assign it.
3118 INIT_LIST_HEAD(&plug
->list
);
3119 INIT_LIST_HEAD(&plug
->mq_list
);
3120 INIT_LIST_HEAD(&plug
->cb_list
);
3122 * Store ordering should not be needed here, since a potential
3123 * preempt will imply a full memory barrier
3127 EXPORT_SYMBOL(blk_start_plug
);
3129 static int plug_rq_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
3131 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
3132 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
3134 return !(rqa
->q
< rqb
->q
||
3135 (rqa
->q
== rqb
->q
&& blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
3139 * If 'from_schedule' is true, then postpone the dispatch of requests
3140 * until a safe kblockd context. We due this to avoid accidental big
3141 * additional stack usage in driver dispatch, in places where the originally
3142 * plugger did not intend it.
3144 static void queue_unplugged(struct request_queue
*q
, unsigned int depth
,
3146 __releases(q
->queue_lock
)
3148 trace_block_unplug(q
, depth
, !from_schedule
);
3151 blk_run_queue_async(q
);
3154 spin_unlock(q
->queue_lock
);
3157 static void flush_plug_callbacks(struct blk_plug
*plug
, bool from_schedule
)
3159 LIST_HEAD(callbacks
);
3161 while (!list_empty(&plug
->cb_list
)) {
3162 list_splice_init(&plug
->cb_list
, &callbacks
);
3164 while (!list_empty(&callbacks
)) {
3165 struct blk_plug_cb
*cb
= list_first_entry(&callbacks
,
3168 list_del(&cb
->list
);
3169 cb
->callback(cb
, from_schedule
);
3174 struct blk_plug_cb
*blk_check_plugged(blk_plug_cb_fn unplug
, void *data
,
3177 struct blk_plug
*plug
= current
->plug
;
3178 struct blk_plug_cb
*cb
;
3183 list_for_each_entry(cb
, &plug
->cb_list
, list
)
3184 if (cb
->callback
== unplug
&& cb
->data
== data
)
3187 /* Not currently on the callback list */
3188 BUG_ON(size
< sizeof(*cb
));
3189 cb
= kzalloc(size
, GFP_ATOMIC
);
3192 cb
->callback
= unplug
;
3193 list_add(&cb
->list
, &plug
->cb_list
);
3197 EXPORT_SYMBOL(blk_check_plugged
);
3199 void blk_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
3201 struct request_queue
*q
;
3202 unsigned long flags
;
3207 flush_plug_callbacks(plug
, from_schedule
);
3209 if (!list_empty(&plug
->mq_list
))
3210 blk_mq_flush_plug_list(plug
, from_schedule
);
3212 if (list_empty(&plug
->list
))
3215 list_splice_init(&plug
->list
, &list
);
3217 list_sort(NULL
, &list
, plug_rq_cmp
);
3223 * Save and disable interrupts here, to avoid doing it for every
3224 * queue lock we have to take.
3226 local_irq_save(flags
);
3227 while (!list_empty(&list
)) {
3228 rq
= list_entry_rq(list
.next
);
3229 list_del_init(&rq
->queuelist
);
3233 * This drops the queue lock
3236 queue_unplugged(q
, depth
, from_schedule
);
3239 spin_lock(q
->queue_lock
);
3243 * Short-circuit if @q is dead
3245 if (unlikely(blk_queue_dying(q
))) {
3246 __blk_end_request_all(rq
, -ENODEV
);
3251 * rq is already accounted, so use raw insert
3253 if (rq
->cmd_flags
& (REQ_FLUSH
| REQ_FUA
))
3254 __elv_add_request(q
, rq
, ELEVATOR_INSERT_FLUSH
);
3256 __elv_add_request(q
, rq
, ELEVATOR_INSERT_SORT_MERGE
);
3262 * This drops the queue lock
3265 queue_unplugged(q
, depth
, from_schedule
);
3267 local_irq_restore(flags
);
3270 void blk_finish_plug(struct blk_plug
*plug
)
3272 if (plug
!= current
->plug
)
3274 blk_flush_plug_list(plug
, false);
3276 current
->plug
= NULL
;
3278 EXPORT_SYMBOL(blk_finish_plug
);
3282 * blk_pm_runtime_init - Block layer runtime PM initialization routine
3283 * @q: the queue of the device
3284 * @dev: the device the queue belongs to
3287 * Initialize runtime-PM-related fields for @q and start auto suspend for
3288 * @dev. Drivers that want to take advantage of request-based runtime PM
3289 * should call this function after @dev has been initialized, and its
3290 * request queue @q has been allocated, and runtime PM for it can not happen
3291 * yet(either due to disabled/forbidden or its usage_count > 0). In most
3292 * cases, driver should call this function before any I/O has taken place.
3294 * This function takes care of setting up using auto suspend for the device,
3295 * the autosuspend delay is set to -1 to make runtime suspend impossible
3296 * until an updated value is either set by user or by driver. Drivers do
3297 * not need to touch other autosuspend settings.
3299 * The block layer runtime PM is request based, so only works for drivers
3300 * that use request as their IO unit instead of those directly use bio's.
3302 void blk_pm_runtime_init(struct request_queue
*q
, struct device
*dev
)
3305 q
->rpm_status
= RPM_ACTIVE
;
3306 pm_runtime_set_autosuspend_delay(q
->dev
, -1);
3307 pm_runtime_use_autosuspend(q
->dev
);
3309 EXPORT_SYMBOL(blk_pm_runtime_init
);
3312 * blk_pre_runtime_suspend - Pre runtime suspend check
3313 * @q: the queue of the device
3316 * This function will check if runtime suspend is allowed for the device
3317 * by examining if there are any requests pending in the queue. If there
3318 * are requests pending, the device can not be runtime suspended; otherwise,
3319 * the queue's status will be updated to SUSPENDING and the driver can
3320 * proceed to suspend the device.
3322 * For the not allowed case, we mark last busy for the device so that
3323 * runtime PM core will try to autosuspend it some time later.
3325 * This function should be called near the start of the device's
3326 * runtime_suspend callback.
3329 * 0 - OK to runtime suspend the device
3330 * -EBUSY - Device should not be runtime suspended
3332 int blk_pre_runtime_suspend(struct request_queue
*q
)
3336 spin_lock_irq(q
->queue_lock
);
3337 if (q
->nr_pending
) {
3339 pm_runtime_mark_last_busy(q
->dev
);
3341 q
->rpm_status
= RPM_SUSPENDING
;
3343 spin_unlock_irq(q
->queue_lock
);
3346 EXPORT_SYMBOL(blk_pre_runtime_suspend
);
3349 * blk_post_runtime_suspend - Post runtime suspend processing
3350 * @q: the queue of the device
3351 * @err: return value of the device's runtime_suspend function
3354 * Update the queue's runtime status according to the return value of the
3355 * device's runtime suspend function and mark last busy for the device so
3356 * that PM core will try to auto suspend the device at a later time.
3358 * This function should be called near the end of the device's
3359 * runtime_suspend callback.
3361 void blk_post_runtime_suspend(struct request_queue
*q
, int err
)
3363 spin_lock_irq(q
->queue_lock
);
3365 q
->rpm_status
= RPM_SUSPENDED
;
3367 q
->rpm_status
= RPM_ACTIVE
;
3368 pm_runtime_mark_last_busy(q
->dev
);
3370 spin_unlock_irq(q
->queue_lock
);
3372 EXPORT_SYMBOL(blk_post_runtime_suspend
);
3375 * blk_pre_runtime_resume - Pre runtime resume processing
3376 * @q: the queue of the device
3379 * Update the queue's runtime status to RESUMING in preparation for the
3380 * runtime resume of the device.
3382 * This function should be called near the start of the device's
3383 * runtime_resume callback.
3385 void blk_pre_runtime_resume(struct request_queue
*q
)
3387 spin_lock_irq(q
->queue_lock
);
3388 q
->rpm_status
= RPM_RESUMING
;
3389 spin_unlock_irq(q
->queue_lock
);
3391 EXPORT_SYMBOL(blk_pre_runtime_resume
);
3394 * blk_post_runtime_resume - Post runtime resume processing
3395 * @q: the queue of the device
3396 * @err: return value of the device's runtime_resume function
3399 * Update the queue's runtime status according to the return value of the
3400 * device's runtime_resume function. If it is successfully resumed, process
3401 * the requests that are queued into the device's queue when it is resuming
3402 * and then mark last busy and initiate autosuspend for it.
3404 * This function should be called near the end of the device's
3405 * runtime_resume callback.
3407 void blk_post_runtime_resume(struct request_queue
*q
, int err
)
3409 spin_lock_irq(q
->queue_lock
);
3411 q
->rpm_status
= RPM_ACTIVE
;
3413 pm_runtime_mark_last_busy(q
->dev
);
3414 pm_request_autosuspend(q
->dev
);
3416 q
->rpm_status
= RPM_SUSPENDED
;
3418 spin_unlock_irq(q
->queue_lock
);
3420 EXPORT_SYMBOL(blk_post_runtime_resume
);
3423 int __init
blk_dev_init(void)
3425 BUILD_BUG_ON(__REQ_NR_BITS
> 8 *
3426 FIELD_SIZEOF(struct request
, cmd_flags
));
3428 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
3429 kblockd_workqueue
= alloc_workqueue("kblockd",
3430 WQ_MEM_RECLAIM
| WQ_HIGHPRI
, 0);
3431 if (!kblockd_workqueue
)
3432 panic("Failed to create kblockd\n");
3434 request_cachep
= kmem_cache_create("blkdev_requests",
3435 sizeof(struct request
), 0, SLAB_PANIC
, NULL
);
3437 blk_requestq_cachep
= kmem_cache_create("blkdev_queue",
3438 sizeof(struct request_queue
), 0, SLAB_PANIC
, NULL
);