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/highmem.h>
21 #include <linux/kernel_stat.h>
22 #include <linux/string.h>
23 #include <linux/init.h>
24 #include <linux/completion.h>
25 #include <linux/slab.h>
26 #include <linux/swap.h>
27 #include <linux/writeback.h>
28 #include <linux/task_io_accounting_ops.h>
29 #include <linux/fault-inject.h>
30 #include <linux/list_sort.h>
31 #include <linux/delay.h>
33 #define CREATE_TRACE_POINTS
34 #include <trace/events/block.h>
37 #include "blk-cgroup.h"
39 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap
);
40 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap
);
41 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete
);
43 DEFINE_IDA(blk_queue_ida
);
46 * For the allocated request tables
48 static struct kmem_cache
*request_cachep
;
51 * For queue allocation
53 struct kmem_cache
*blk_requestq_cachep
;
56 * Controlling structure to kblockd
58 static struct workqueue_struct
*kblockd_workqueue
;
60 static void drive_stat_acct(struct request
*rq
, int new_io
)
62 struct hd_struct
*part
;
63 int rw
= rq_data_dir(rq
);
66 if (!blk_do_io_stat(rq
))
69 cpu
= part_stat_lock();
73 part_stat_inc(cpu
, part
, merges
[rw
]);
75 part
= disk_map_sector_rcu(rq
->rq_disk
, blk_rq_pos(rq
));
76 if (!hd_struct_try_get(part
)) {
78 * The partition is already being removed,
79 * the request will be accounted on the disk only
81 * We take a reference on disk->part0 although that
82 * partition will never be deleted, so we can treat
83 * it as any other partition.
85 part
= &rq
->rq_disk
->part0
;
88 part_round_stats(cpu
, part
);
89 part_inc_in_flight(part
, rw
);
96 void blk_queue_congestion_threshold(struct request_queue
*q
)
100 nr
= q
->nr_requests
- (q
->nr_requests
/ 8) + 1;
101 if (nr
> q
->nr_requests
)
103 q
->nr_congestion_on
= nr
;
105 nr
= q
->nr_requests
- (q
->nr_requests
/ 8) - (q
->nr_requests
/ 16) - 1;
108 q
->nr_congestion_off
= nr
;
112 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
115 * Locates the passed device's request queue and returns the address of its
118 * Will return NULL if the request queue cannot be located.
120 struct backing_dev_info
*blk_get_backing_dev_info(struct block_device
*bdev
)
122 struct backing_dev_info
*ret
= NULL
;
123 struct request_queue
*q
= bdev_get_queue(bdev
);
126 ret
= &q
->backing_dev_info
;
129 EXPORT_SYMBOL(blk_get_backing_dev_info
);
131 void blk_rq_init(struct request_queue
*q
, struct request
*rq
)
133 memset(rq
, 0, sizeof(*rq
));
135 INIT_LIST_HEAD(&rq
->queuelist
);
136 INIT_LIST_HEAD(&rq
->timeout_list
);
139 rq
->__sector
= (sector_t
) -1;
140 INIT_HLIST_NODE(&rq
->hash
);
141 RB_CLEAR_NODE(&rq
->rb_node
);
143 rq
->cmd_len
= BLK_MAX_CDB
;
146 rq
->start_time
= jiffies
;
147 set_start_time_ns(rq
);
150 EXPORT_SYMBOL(blk_rq_init
);
152 static void req_bio_endio(struct request
*rq
, struct bio
*bio
,
153 unsigned int nbytes
, int error
)
156 clear_bit(BIO_UPTODATE
, &bio
->bi_flags
);
157 else if (!test_bit(BIO_UPTODATE
, &bio
->bi_flags
))
160 if (unlikely(nbytes
> bio
->bi_size
)) {
161 printk(KERN_ERR
"%s: want %u bytes done, %u left\n",
162 __func__
, nbytes
, bio
->bi_size
);
163 nbytes
= bio
->bi_size
;
166 if (unlikely(rq
->cmd_flags
& REQ_QUIET
))
167 set_bit(BIO_QUIET
, &bio
->bi_flags
);
169 bio
->bi_size
-= nbytes
;
170 bio
->bi_sector
+= (nbytes
>> 9);
172 if (bio_integrity(bio
))
173 bio_integrity_advance(bio
, nbytes
);
175 /* don't actually finish bio if it's part of flush sequence */
176 if (bio
->bi_size
== 0 && !(rq
->cmd_flags
& REQ_FLUSH_SEQ
))
177 bio_endio(bio
, error
);
180 void blk_dump_rq_flags(struct request
*rq
, char *msg
)
184 printk(KERN_INFO
"%s: dev %s: type=%x, flags=%x\n", msg
,
185 rq
->rq_disk
? rq
->rq_disk
->disk_name
: "?", rq
->cmd_type
,
188 printk(KERN_INFO
" sector %llu, nr/cnr %u/%u\n",
189 (unsigned long long)blk_rq_pos(rq
),
190 blk_rq_sectors(rq
), blk_rq_cur_sectors(rq
));
191 printk(KERN_INFO
" bio %p, biotail %p, buffer %p, len %u\n",
192 rq
->bio
, rq
->biotail
, rq
->buffer
, blk_rq_bytes(rq
));
194 if (rq
->cmd_type
== REQ_TYPE_BLOCK_PC
) {
195 printk(KERN_INFO
" cdb: ");
196 for (bit
= 0; bit
< BLK_MAX_CDB
; bit
++)
197 printk("%02x ", rq
->cmd
[bit
]);
201 EXPORT_SYMBOL(blk_dump_rq_flags
);
203 static void blk_delay_work(struct work_struct
*work
)
205 struct request_queue
*q
;
207 q
= container_of(work
, struct request_queue
, delay_work
.work
);
208 spin_lock_irq(q
->queue_lock
);
210 spin_unlock_irq(q
->queue_lock
);
214 * blk_delay_queue - restart queueing after defined interval
215 * @q: The &struct request_queue in question
216 * @msecs: Delay in msecs
219 * Sometimes queueing needs to be postponed for a little while, to allow
220 * resources to come back. This function will make sure that queueing is
221 * restarted around the specified time.
223 void blk_delay_queue(struct request_queue
*q
, unsigned long msecs
)
225 queue_delayed_work(kblockd_workqueue
, &q
->delay_work
,
226 msecs_to_jiffies(msecs
));
228 EXPORT_SYMBOL(blk_delay_queue
);
231 * blk_start_queue - restart a previously stopped queue
232 * @q: The &struct request_queue in question
235 * blk_start_queue() will clear the stop flag on the queue, and call
236 * the request_fn for the queue if it was in a stopped state when
237 * entered. Also see blk_stop_queue(). Queue lock must be held.
239 void blk_start_queue(struct request_queue
*q
)
241 WARN_ON(!irqs_disabled());
243 queue_flag_clear(QUEUE_FLAG_STOPPED
, q
);
246 EXPORT_SYMBOL(blk_start_queue
);
249 * blk_stop_queue - stop a queue
250 * @q: The &struct request_queue in question
253 * The Linux block layer assumes that a block driver will consume all
254 * entries on the request queue when the request_fn strategy is called.
255 * Often this will not happen, because of hardware limitations (queue
256 * depth settings). If a device driver gets a 'queue full' response,
257 * or if it simply chooses not to queue more I/O at one point, it can
258 * call this function to prevent the request_fn from being called until
259 * the driver has signalled it's ready to go again. This happens by calling
260 * blk_start_queue() to restart queue operations. Queue lock must be held.
262 void blk_stop_queue(struct request_queue
*q
)
264 __cancel_delayed_work(&q
->delay_work
);
265 queue_flag_set(QUEUE_FLAG_STOPPED
, q
);
267 EXPORT_SYMBOL(blk_stop_queue
);
270 * blk_sync_queue - cancel any pending callbacks on a queue
274 * The block layer may perform asynchronous callback activity
275 * on a queue, such as calling the unplug function after a timeout.
276 * A block device may call blk_sync_queue to ensure that any
277 * such activity is cancelled, thus allowing it to release resources
278 * that the callbacks might use. The caller must already have made sure
279 * that its ->make_request_fn will not re-add plugging prior to calling
282 * This function does not cancel any asynchronous activity arising
283 * out of elevator or throttling code. That would require elevaotor_exit()
284 * and blkcg_exit_queue() to be called with queue lock initialized.
287 void blk_sync_queue(struct request_queue
*q
)
289 del_timer_sync(&q
->timeout
);
290 cancel_delayed_work_sync(&q
->delay_work
);
292 EXPORT_SYMBOL(blk_sync_queue
);
295 * __blk_run_queue - run a single device queue
296 * @q: The queue to run
299 * See @blk_run_queue. This variant must be called with the queue lock
300 * held and interrupts disabled.
302 void __blk_run_queue(struct request_queue
*q
)
304 if (unlikely(blk_queue_stopped(q
)))
309 EXPORT_SYMBOL(__blk_run_queue
);
312 * blk_run_queue_async - run a single device queue in workqueue context
313 * @q: The queue to run
316 * Tells kblockd to perform the equivalent of @blk_run_queue on behalf
319 void blk_run_queue_async(struct request_queue
*q
)
321 if (likely(!blk_queue_stopped(q
))) {
322 __cancel_delayed_work(&q
->delay_work
);
323 queue_delayed_work(kblockd_workqueue
, &q
->delay_work
, 0);
326 EXPORT_SYMBOL(blk_run_queue_async
);
329 * blk_run_queue - run a single device queue
330 * @q: The queue to run
333 * Invoke request handling on this queue, if it has pending work to do.
334 * May be used to restart queueing when a request has completed.
336 void blk_run_queue(struct request_queue
*q
)
340 spin_lock_irqsave(q
->queue_lock
, flags
);
342 spin_unlock_irqrestore(q
->queue_lock
, flags
);
344 EXPORT_SYMBOL(blk_run_queue
);
346 void blk_put_queue(struct request_queue
*q
)
348 kobject_put(&q
->kobj
);
350 EXPORT_SYMBOL(blk_put_queue
);
353 * blk_drain_queue - drain requests from request_queue
355 * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
357 * Drain requests from @q. If @drain_all is set, all requests are drained.
358 * If not, only ELVPRIV requests are drained. The caller is responsible
359 * for ensuring that no new requests which need to be drained are queued.
361 void blk_drain_queue(struct request_queue
*q
, bool drain_all
)
367 spin_lock_irq(q
->queue_lock
);
370 * The caller might be trying to drain @q before its
371 * elevator is initialized.
374 elv_drain_elevator(q
);
376 blkcg_drain_queue(q
);
379 * This function might be called on a queue which failed
380 * driver init after queue creation or is not yet fully
381 * active yet. Some drivers (e.g. fd and loop) get unhappy
382 * in such cases. Kick queue iff dispatch queue has
383 * something on it and @q has request_fn set.
385 if (!list_empty(&q
->queue_head
) && q
->request_fn
)
388 drain
|= q
->rq
.elvpriv
;
391 * Unfortunately, requests are queued at and tracked from
392 * multiple places and there's no single counter which can
393 * be drained. Check all the queues and counters.
396 drain
|= !list_empty(&q
->queue_head
);
397 for (i
= 0; i
< 2; i
++) {
398 drain
|= q
->rq
.count
[i
];
399 drain
|= q
->in_flight
[i
];
400 drain
|= !list_empty(&q
->flush_queue
[i
]);
404 spin_unlock_irq(q
->queue_lock
);
413 * blk_queue_bypass_start - enter queue bypass mode
414 * @q: queue of interest
416 * In bypass mode, only the dispatch FIFO queue of @q is used. This
417 * function makes @q enter bypass mode and drains all requests which were
418 * throttled or issued before. On return, it's guaranteed that no request
419 * is being throttled or has ELVPRIV set.
421 void blk_queue_bypass_start(struct request_queue
*q
)
423 spin_lock_irq(q
->queue_lock
);
425 queue_flag_set(QUEUE_FLAG_BYPASS
, q
);
426 spin_unlock_irq(q
->queue_lock
);
428 blk_drain_queue(q
, false);
430 EXPORT_SYMBOL_GPL(blk_queue_bypass_start
);
433 * blk_queue_bypass_end - leave queue bypass mode
434 * @q: queue of interest
436 * Leave bypass mode and restore the normal queueing behavior.
438 void blk_queue_bypass_end(struct request_queue
*q
)
440 spin_lock_irq(q
->queue_lock
);
441 if (!--q
->bypass_depth
)
442 queue_flag_clear(QUEUE_FLAG_BYPASS
, q
);
443 WARN_ON_ONCE(q
->bypass_depth
< 0);
444 spin_unlock_irq(q
->queue_lock
);
446 EXPORT_SYMBOL_GPL(blk_queue_bypass_end
);
449 * blk_cleanup_queue - shutdown a request queue
450 * @q: request queue to shutdown
452 * Mark @q DEAD, drain all pending requests, destroy and put it. All
453 * future requests will be failed immediately with -ENODEV.
455 void blk_cleanup_queue(struct request_queue
*q
)
457 spinlock_t
*lock
= q
->queue_lock
;
459 /* mark @q DEAD, no new request or merges will be allowed afterwards */
460 mutex_lock(&q
->sysfs_lock
);
461 queue_flag_set_unlocked(QUEUE_FLAG_DEAD
, q
);
465 /* dead queue is permanently in bypass mode till released */
467 queue_flag_set(QUEUE_FLAG_BYPASS
, q
);
469 queue_flag_set(QUEUE_FLAG_NOMERGES
, q
);
470 queue_flag_set(QUEUE_FLAG_NOXMERGES
, q
);
471 queue_flag_set(QUEUE_FLAG_DEAD
, q
);
473 if (q
->queue_lock
!= &q
->__queue_lock
)
474 q
->queue_lock
= &q
->__queue_lock
;
476 spin_unlock_irq(lock
);
477 mutex_unlock(&q
->sysfs_lock
);
479 /* drain all requests queued before DEAD marking */
480 blk_drain_queue(q
, true);
482 /* @q won't process any more request, flush async actions */
483 del_timer_sync(&q
->backing_dev_info
.laptop_mode_wb_timer
);
486 /* @q is and will stay empty, shutdown and put */
489 EXPORT_SYMBOL(blk_cleanup_queue
);
491 static int blk_init_free_list(struct request_queue
*q
)
493 struct request_list
*rl
= &q
->rq
;
495 if (unlikely(rl
->rq_pool
))
498 rl
->count
[BLK_RW_SYNC
] = rl
->count
[BLK_RW_ASYNC
] = 0;
499 rl
->starved
[BLK_RW_SYNC
] = rl
->starved
[BLK_RW_ASYNC
] = 0;
501 init_waitqueue_head(&rl
->wait
[BLK_RW_SYNC
]);
502 init_waitqueue_head(&rl
->wait
[BLK_RW_ASYNC
]);
504 rl
->rq_pool
= mempool_create_node(BLKDEV_MIN_RQ
, mempool_alloc_slab
,
505 mempool_free_slab
, request_cachep
, q
->node
);
513 struct request_queue
*blk_alloc_queue(gfp_t gfp_mask
)
515 return blk_alloc_queue_node(gfp_mask
, -1);
517 EXPORT_SYMBOL(blk_alloc_queue
);
519 struct request_queue
*blk_alloc_queue_node(gfp_t gfp_mask
, int node_id
)
521 struct request_queue
*q
;
524 q
= kmem_cache_alloc_node(blk_requestq_cachep
,
525 gfp_mask
| __GFP_ZERO
, node_id
);
529 q
->id
= ida_simple_get(&blk_queue_ida
, 0, 0, GFP_KERNEL
);
533 q
->backing_dev_info
.ra_pages
=
534 (VM_MAX_READAHEAD
* 1024) / PAGE_CACHE_SIZE
;
535 q
->backing_dev_info
.state
= 0;
536 q
->backing_dev_info
.capabilities
= BDI_CAP_MAP_COPY
;
537 q
->backing_dev_info
.name
= "block";
540 err
= bdi_init(&q
->backing_dev_info
);
544 setup_timer(&q
->backing_dev_info
.laptop_mode_wb_timer
,
545 laptop_mode_timer_fn
, (unsigned long) q
);
546 setup_timer(&q
->timeout
, blk_rq_timed_out_timer
, (unsigned long) q
);
547 INIT_LIST_HEAD(&q
->queue_head
);
548 INIT_LIST_HEAD(&q
->timeout_list
);
549 INIT_LIST_HEAD(&q
->icq_list
);
550 #ifdef CONFIG_BLK_CGROUP
551 INIT_LIST_HEAD(&q
->blkg_list
);
553 INIT_LIST_HEAD(&q
->flush_queue
[0]);
554 INIT_LIST_HEAD(&q
->flush_queue
[1]);
555 INIT_LIST_HEAD(&q
->flush_data_in_flight
);
556 INIT_DELAYED_WORK(&q
->delay_work
, blk_delay_work
);
558 kobject_init(&q
->kobj
, &blk_queue_ktype
);
560 mutex_init(&q
->sysfs_lock
);
561 spin_lock_init(&q
->__queue_lock
);
564 * By default initialize queue_lock to internal lock and driver can
565 * override it later if need be.
567 q
->queue_lock
= &q
->__queue_lock
;
569 if (blkcg_init_queue(q
))
575 ida_simple_remove(&blk_queue_ida
, q
->id
);
577 kmem_cache_free(blk_requestq_cachep
, q
);
580 EXPORT_SYMBOL(blk_alloc_queue_node
);
583 * blk_init_queue - prepare a request queue for use with a block device
584 * @rfn: The function to be called to process requests that have been
585 * placed on the queue.
586 * @lock: Request queue spin lock
589 * If a block device wishes to use the standard request handling procedures,
590 * which sorts requests and coalesces adjacent requests, then it must
591 * call blk_init_queue(). The function @rfn will be called when there
592 * are requests on the queue that need to be processed. If the device
593 * supports plugging, then @rfn may not be called immediately when requests
594 * are available on the queue, but may be called at some time later instead.
595 * Plugged queues are generally unplugged when a buffer belonging to one
596 * of the requests on the queue is needed, or due to memory pressure.
598 * @rfn is not required, or even expected, to remove all requests off the
599 * queue, but only as many as it can handle at a time. If it does leave
600 * requests on the queue, it is responsible for arranging that the requests
601 * get dealt with eventually.
603 * The queue spin lock must be held while manipulating the requests on the
604 * request queue; this lock will be taken also from interrupt context, so irq
605 * disabling is needed for it.
607 * Function returns a pointer to the initialized request queue, or %NULL if
611 * blk_init_queue() must be paired with a blk_cleanup_queue() call
612 * when the block device is deactivated (such as at module unload).
615 struct request_queue
*blk_init_queue(request_fn_proc
*rfn
, spinlock_t
*lock
)
617 return blk_init_queue_node(rfn
, lock
, -1);
619 EXPORT_SYMBOL(blk_init_queue
);
621 struct request_queue
*
622 blk_init_queue_node(request_fn_proc
*rfn
, spinlock_t
*lock
, int node_id
)
624 struct request_queue
*uninit_q
, *q
;
626 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, node_id
);
630 q
= blk_init_allocated_queue(uninit_q
, rfn
, lock
);
632 blk_cleanup_queue(uninit_q
);
636 EXPORT_SYMBOL(blk_init_queue_node
);
638 struct request_queue
*
639 blk_init_allocated_queue(struct request_queue
*q
, request_fn_proc
*rfn
,
645 if (blk_init_free_list(q
))
649 q
->prep_rq_fn
= NULL
;
650 q
->unprep_rq_fn
= NULL
;
651 q
->queue_flags
= QUEUE_FLAG_DEFAULT
;
653 /* Override internal queue lock with supplied lock pointer */
655 q
->queue_lock
= lock
;
658 * This also sets hw/phys segments, boundary and size
660 blk_queue_make_request(q
, blk_queue_bio
);
662 q
->sg_reserved_size
= INT_MAX
;
667 if (!elevator_init(q
, NULL
)) {
668 blk_queue_congestion_threshold(q
);
674 EXPORT_SYMBOL(blk_init_allocated_queue
);
676 bool blk_get_queue(struct request_queue
*q
)
678 if (likely(!blk_queue_dead(q
))) {
685 EXPORT_SYMBOL(blk_get_queue
);
687 static inline void blk_free_request(struct request_queue
*q
, struct request
*rq
)
689 if (rq
->cmd_flags
& REQ_ELVPRIV
) {
690 elv_put_request(q
, rq
);
692 put_io_context(rq
->elv
.icq
->ioc
);
695 mempool_free(rq
, q
->rq
.rq_pool
);
698 static struct request
*
699 blk_alloc_request(struct request_queue
*q
, struct bio
*bio
, struct io_cq
*icq
,
700 unsigned int flags
, gfp_t gfp_mask
)
702 struct request
*rq
= mempool_alloc(q
->rq
.rq_pool
, gfp_mask
);
709 rq
->cmd_flags
= flags
| REQ_ALLOCED
;
711 if (flags
& REQ_ELVPRIV
) {
713 if (unlikely(elv_set_request(q
, rq
, bio
, gfp_mask
))) {
714 mempool_free(rq
, q
->rq
.rq_pool
);
717 /* @rq->elv.icq holds on to io_context until @rq is freed */
719 get_io_context(icq
->ioc
);
726 * ioc_batching returns true if the ioc is a valid batching request and
727 * should be given priority access to a request.
729 static inline int ioc_batching(struct request_queue
*q
, struct io_context
*ioc
)
735 * Make sure the process is able to allocate at least 1 request
736 * even if the batch times out, otherwise we could theoretically
739 return ioc
->nr_batch_requests
== q
->nr_batching
||
740 (ioc
->nr_batch_requests
> 0
741 && time_before(jiffies
, ioc
->last_waited
+ BLK_BATCH_TIME
));
745 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
746 * will cause the process to be a "batcher" on all queues in the system. This
747 * is the behaviour we want though - once it gets a wakeup it should be given
750 static void ioc_set_batching(struct request_queue
*q
, struct io_context
*ioc
)
752 if (!ioc
|| ioc_batching(q
, ioc
))
755 ioc
->nr_batch_requests
= q
->nr_batching
;
756 ioc
->last_waited
= jiffies
;
759 static void __freed_request(struct request_queue
*q
, int sync
)
761 struct request_list
*rl
= &q
->rq
;
763 if (rl
->count
[sync
] < queue_congestion_off_threshold(q
))
764 blk_clear_queue_congested(q
, sync
);
766 if (rl
->count
[sync
] + 1 <= q
->nr_requests
) {
767 if (waitqueue_active(&rl
->wait
[sync
]))
768 wake_up(&rl
->wait
[sync
]);
770 blk_clear_queue_full(q
, sync
);
775 * A request has just been released. Account for it, update the full and
776 * congestion status, wake up any waiters. Called under q->queue_lock.
778 static void freed_request(struct request_queue
*q
, unsigned int flags
)
780 struct request_list
*rl
= &q
->rq
;
781 int sync
= rw_is_sync(flags
);
784 if (flags
& REQ_ELVPRIV
)
787 __freed_request(q
, sync
);
789 if (unlikely(rl
->starved
[sync
^ 1]))
790 __freed_request(q
, sync
^ 1);
794 * Determine if elevator data should be initialized when allocating the
795 * request associated with @bio.
797 static bool blk_rq_should_init_elevator(struct bio
*bio
)
803 * Flush requests do not use the elevator so skip initialization.
804 * This allows a request to share the flush and elevator data.
806 if (bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
))
813 * rq_ioc - determine io_context for request allocation
814 * @bio: request being allocated is for this bio (can be %NULL)
816 * Determine io_context to use for request allocation for @bio. May return
817 * %NULL if %current->io_context doesn't exist.
819 static struct io_context
*rq_ioc(struct bio
*bio
)
821 #ifdef CONFIG_BLK_CGROUP
822 if (bio
&& bio
->bi_ioc
)
825 return current
->io_context
;
829 * get_request - get a free request
830 * @q: request_queue to allocate request from
831 * @rw_flags: RW and SYNC flags
832 * @bio: bio to allocate request for (can be %NULL)
833 * @gfp_mask: allocation mask
835 * Get a free request from @q. This function may fail under memory
836 * pressure or if @q is dead.
838 * Must be callled with @q->queue_lock held and,
839 * Returns %NULL on failure, with @q->queue_lock held.
840 * Returns !%NULL on success, with @q->queue_lock *not held*.
842 static struct request
*get_request(struct request_queue
*q
, int rw_flags
,
843 struct bio
*bio
, gfp_t gfp_mask
)
846 struct request_list
*rl
= &q
->rq
;
847 struct elevator_type
*et
;
848 struct io_context
*ioc
;
849 struct io_cq
*icq
= NULL
;
850 const bool is_sync
= rw_is_sync(rw_flags
) != 0;
851 bool retried
= false;
854 et
= q
->elevator
->type
;
857 if (unlikely(blk_queue_dead(q
)))
860 may_queue
= elv_may_queue(q
, rw_flags
);
861 if (may_queue
== ELV_MQUEUE_NO
)
864 if (rl
->count
[is_sync
]+1 >= queue_congestion_on_threshold(q
)) {
865 if (rl
->count
[is_sync
]+1 >= q
->nr_requests
) {
867 * We want ioc to record batching state. If it's
868 * not already there, creating a new one requires
869 * dropping queue_lock, which in turn requires
870 * retesting conditions to avoid queue hang.
872 if (!ioc
&& !retried
) {
873 spin_unlock_irq(q
->queue_lock
);
874 create_io_context(gfp_mask
, q
->node
);
875 spin_lock_irq(q
->queue_lock
);
881 * The queue will fill after this allocation, so set
882 * it as full, and mark this process as "batching".
883 * This process will be allowed to complete a batch of
884 * requests, others will be blocked.
886 if (!blk_queue_full(q
, is_sync
)) {
887 ioc_set_batching(q
, ioc
);
888 blk_set_queue_full(q
, is_sync
);
890 if (may_queue
!= ELV_MQUEUE_MUST
891 && !ioc_batching(q
, ioc
)) {
893 * The queue is full and the allocating
894 * process is not a "batcher", and not
895 * exempted by the IO scheduler
901 blk_set_queue_congested(q
, is_sync
);
905 * Only allow batching queuers to allocate up to 50% over the defined
906 * limit of requests, otherwise we could have thousands of requests
907 * allocated with any setting of ->nr_requests
909 if (rl
->count
[is_sync
] >= (3 * q
->nr_requests
/ 2))
912 rl
->count
[is_sync
]++;
913 rl
->starved
[is_sync
] = 0;
916 * Decide whether the new request will be managed by elevator. If
917 * so, mark @rw_flags and increment elvpriv. Non-zero elvpriv will
918 * prevent the current elevator from being destroyed until the new
919 * request is freed. This guarantees icq's won't be destroyed and
920 * makes creating new ones safe.
922 * Also, lookup icq while holding queue_lock. If it doesn't exist,
923 * it will be created after releasing queue_lock.
925 if (blk_rq_should_init_elevator(bio
) && !blk_queue_bypass(q
)) {
926 rw_flags
|= REQ_ELVPRIV
;
928 if (et
->icq_cache
&& ioc
)
929 icq
= ioc_lookup_icq(ioc
, q
);
932 if (blk_queue_io_stat(q
))
933 rw_flags
|= REQ_IO_STAT
;
934 spin_unlock_irq(q
->queue_lock
);
936 /* create icq if missing */
937 if ((rw_flags
& REQ_ELVPRIV
) && unlikely(et
->icq_cache
&& !icq
)) {
938 create_io_context(gfp_mask
, q
->node
);
942 icq
= ioc_create_icq(ioc
, q
, gfp_mask
);
947 rq
= blk_alloc_request(q
, bio
, icq
, rw_flags
, gfp_mask
);
952 * ioc may be NULL here, and ioc_batching will be false. That's
953 * OK, if the queue is under the request limit then requests need
954 * not count toward the nr_batch_requests limit. There will always
955 * be some limit enforced by BLK_BATCH_TIME.
957 if (ioc_batching(q
, ioc
))
958 ioc
->nr_batch_requests
--;
960 trace_block_getrq(q
, bio
, rw_flags
& 1);
965 * Allocation failed presumably due to memory. Undo anything we
966 * might have messed up.
968 * Allocating task should really be put onto the front of the wait
969 * queue, but this is pretty rare.
971 spin_lock_irq(q
->queue_lock
);
972 freed_request(q
, rw_flags
);
975 * in the very unlikely event that allocation failed and no
976 * requests for this direction was pending, mark us starved so that
977 * freeing of a request in the other direction will notice
978 * us. another possible fix would be to split the rq mempool into
982 if (unlikely(rl
->count
[is_sync
] == 0))
983 rl
->starved
[is_sync
] = 1;
988 * get_request_wait - get a free request with retry
989 * @q: request_queue to allocate request from
990 * @rw_flags: RW and SYNC flags
991 * @bio: bio to allocate request for (can be %NULL)
993 * Get a free request from @q. This function keeps retrying under memory
994 * pressure and fails iff @q is dead.
996 * Must be callled with @q->queue_lock held and,
997 * Returns %NULL on failure, with @q->queue_lock held.
998 * Returns !%NULL on success, with @q->queue_lock *not held*.
1000 static struct request
*get_request_wait(struct request_queue
*q
, int rw_flags
,
1003 const bool is_sync
= rw_is_sync(rw_flags
) != 0;
1006 rq
= get_request(q
, rw_flags
, bio
, GFP_NOIO
);
1009 struct request_list
*rl
= &q
->rq
;
1011 if (unlikely(blk_queue_dead(q
)))
1014 prepare_to_wait_exclusive(&rl
->wait
[is_sync
], &wait
,
1015 TASK_UNINTERRUPTIBLE
);
1017 trace_block_sleeprq(q
, bio
, rw_flags
& 1);
1019 spin_unlock_irq(q
->queue_lock
);
1023 * After sleeping, we become a "batching" process and
1024 * will be able to allocate at least one request, and
1025 * up to a big batch of them for a small period time.
1026 * See ioc_batching, ioc_set_batching
1028 create_io_context(GFP_NOIO
, q
->node
);
1029 ioc_set_batching(q
, current
->io_context
);
1031 spin_lock_irq(q
->queue_lock
);
1032 finish_wait(&rl
->wait
[is_sync
], &wait
);
1034 rq
= get_request(q
, rw_flags
, bio
, GFP_NOIO
);
1040 struct request
*blk_get_request(struct request_queue
*q
, int rw
, gfp_t gfp_mask
)
1044 BUG_ON(rw
!= READ
&& rw
!= WRITE
);
1046 spin_lock_irq(q
->queue_lock
);
1047 if (gfp_mask
& __GFP_WAIT
)
1048 rq
= get_request_wait(q
, rw
, NULL
);
1050 rq
= get_request(q
, rw
, NULL
, gfp_mask
);
1052 spin_unlock_irq(q
->queue_lock
);
1053 /* q->queue_lock is unlocked at this point */
1057 EXPORT_SYMBOL(blk_get_request
);
1060 * blk_make_request - given a bio, allocate a corresponding struct request.
1061 * @q: target request queue
1062 * @bio: The bio describing the memory mappings that will be submitted for IO.
1063 * It may be a chained-bio properly constructed by block/bio layer.
1064 * @gfp_mask: gfp flags to be used for memory allocation
1066 * blk_make_request is the parallel of generic_make_request for BLOCK_PC
1067 * type commands. Where the struct request needs to be farther initialized by
1068 * the caller. It is passed a &struct bio, which describes the memory info of
1071 * The caller of blk_make_request must make sure that bi_io_vec
1072 * are set to describe the memory buffers. That bio_data_dir() will return
1073 * the needed direction of the request. (And all bio's in the passed bio-chain
1074 * are properly set accordingly)
1076 * If called under none-sleepable conditions, mapped bio buffers must not
1077 * need bouncing, by calling the appropriate masked or flagged allocator,
1078 * suitable for the target device. Otherwise the call to blk_queue_bounce will
1081 * WARNING: When allocating/cloning a bio-chain, careful consideration should be
1082 * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for
1083 * anything but the first bio in the chain. Otherwise you risk waiting for IO
1084 * completion of a bio that hasn't been submitted yet, thus resulting in a
1085 * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead
1086 * of bio_alloc(), as that avoids the mempool deadlock.
1087 * If possible a big IO should be split into smaller parts when allocation
1088 * fails. Partial allocation should not be an error, or you risk a live-lock.
1090 struct request
*blk_make_request(struct request_queue
*q
, struct bio
*bio
,
1093 struct request
*rq
= blk_get_request(q
, bio_data_dir(bio
), gfp_mask
);
1096 return ERR_PTR(-ENOMEM
);
1099 struct bio
*bounce_bio
= bio
;
1102 blk_queue_bounce(q
, &bounce_bio
);
1103 ret
= blk_rq_append_bio(q
, rq
, bounce_bio
);
1104 if (unlikely(ret
)) {
1105 blk_put_request(rq
);
1106 return ERR_PTR(ret
);
1112 EXPORT_SYMBOL(blk_make_request
);
1115 * blk_requeue_request - put a request back on queue
1116 * @q: request queue where request should be inserted
1117 * @rq: request to be inserted
1120 * Drivers often keep queueing requests until the hardware cannot accept
1121 * more, when that condition happens we need to put the request back
1122 * on the queue. Must be called with queue lock held.
1124 void blk_requeue_request(struct request_queue
*q
, struct request
*rq
)
1126 blk_delete_timer(rq
);
1127 blk_clear_rq_complete(rq
);
1128 trace_block_rq_requeue(q
, rq
);
1130 if (blk_rq_tagged(rq
))
1131 blk_queue_end_tag(q
, rq
);
1133 BUG_ON(blk_queued_rq(rq
));
1135 elv_requeue_request(q
, rq
);
1137 EXPORT_SYMBOL(blk_requeue_request
);
1139 static void add_acct_request(struct request_queue
*q
, struct request
*rq
,
1142 drive_stat_acct(rq
, 1);
1143 __elv_add_request(q
, rq
, where
);
1146 static void part_round_stats_single(int cpu
, struct hd_struct
*part
,
1149 if (now
== part
->stamp
)
1152 if (part_in_flight(part
)) {
1153 __part_stat_add(cpu
, part
, time_in_queue
,
1154 part_in_flight(part
) * (now
- part
->stamp
));
1155 __part_stat_add(cpu
, part
, io_ticks
, (now
- part
->stamp
));
1161 * part_round_stats() - Round off the performance stats on a struct disk_stats.
1162 * @cpu: cpu number for stats access
1163 * @part: target partition
1165 * The average IO queue length and utilisation statistics are maintained
1166 * by observing the current state of the queue length and the amount of
1167 * time it has been in this state for.
1169 * Normally, that accounting is done on IO completion, but that can result
1170 * in more than a second's worth of IO being accounted for within any one
1171 * second, leading to >100% utilisation. To deal with that, we call this
1172 * function to do a round-off before returning the results when reading
1173 * /proc/diskstats. This accounts immediately for all queue usage up to
1174 * the current jiffies and restarts the counters again.
1176 void part_round_stats(int cpu
, struct hd_struct
*part
)
1178 unsigned long now
= jiffies
;
1181 part_round_stats_single(cpu
, &part_to_disk(part
)->part0
, now
);
1182 part_round_stats_single(cpu
, part
, now
);
1184 EXPORT_SYMBOL_GPL(part_round_stats
);
1187 * queue lock must be held
1189 void __blk_put_request(struct request_queue
*q
, struct request
*req
)
1193 if (unlikely(--req
->ref_count
))
1196 elv_completed_request(q
, req
);
1198 /* this is a bio leak */
1199 WARN_ON(req
->bio
!= NULL
);
1202 * Request may not have originated from ll_rw_blk. if not,
1203 * it didn't come out of our reserved rq pools
1205 if (req
->cmd_flags
& REQ_ALLOCED
) {
1206 unsigned int flags
= req
->cmd_flags
;
1208 BUG_ON(!list_empty(&req
->queuelist
));
1209 BUG_ON(!hlist_unhashed(&req
->hash
));
1211 blk_free_request(q
, req
);
1212 freed_request(q
, flags
);
1215 EXPORT_SYMBOL_GPL(__blk_put_request
);
1217 void blk_put_request(struct request
*req
)
1219 unsigned long flags
;
1220 struct request_queue
*q
= req
->q
;
1222 spin_lock_irqsave(q
->queue_lock
, flags
);
1223 __blk_put_request(q
, req
);
1224 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1226 EXPORT_SYMBOL(blk_put_request
);
1229 * blk_add_request_payload - add a payload to a request
1230 * @rq: request to update
1231 * @page: page backing the payload
1232 * @len: length of the payload.
1234 * This allows to later add a payload to an already submitted request by
1235 * a block driver. The driver needs to take care of freeing the payload
1238 * Note that this is a quite horrible hack and nothing but handling of
1239 * discard requests should ever use it.
1241 void blk_add_request_payload(struct request
*rq
, struct page
*page
,
1244 struct bio
*bio
= rq
->bio
;
1246 bio
->bi_io_vec
->bv_page
= page
;
1247 bio
->bi_io_vec
->bv_offset
= 0;
1248 bio
->bi_io_vec
->bv_len
= len
;
1252 bio
->bi_phys_segments
= 1;
1254 rq
->__data_len
= rq
->resid_len
= len
;
1255 rq
->nr_phys_segments
= 1;
1256 rq
->buffer
= bio_data(bio
);
1258 EXPORT_SYMBOL_GPL(blk_add_request_payload
);
1260 static bool bio_attempt_back_merge(struct request_queue
*q
, struct request
*req
,
1263 const int ff
= bio
->bi_rw
& REQ_FAILFAST_MASK
;
1265 if (!ll_back_merge_fn(q
, req
, bio
))
1268 trace_block_bio_backmerge(q
, bio
);
1270 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
1271 blk_rq_set_mixed_merge(req
);
1273 req
->biotail
->bi_next
= bio
;
1275 req
->__data_len
+= bio
->bi_size
;
1276 req
->ioprio
= ioprio_best(req
->ioprio
, bio_prio(bio
));
1278 drive_stat_acct(req
, 0);
1282 static bool bio_attempt_front_merge(struct request_queue
*q
,
1283 struct request
*req
, struct bio
*bio
)
1285 const int ff
= bio
->bi_rw
& REQ_FAILFAST_MASK
;
1287 if (!ll_front_merge_fn(q
, req
, bio
))
1290 trace_block_bio_frontmerge(q
, bio
);
1292 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
1293 blk_rq_set_mixed_merge(req
);
1295 bio
->bi_next
= req
->bio
;
1299 * may not be valid. if the low level driver said
1300 * it didn't need a bounce buffer then it better
1301 * not touch req->buffer either...
1303 req
->buffer
= bio_data(bio
);
1304 req
->__sector
= bio
->bi_sector
;
1305 req
->__data_len
+= bio
->bi_size
;
1306 req
->ioprio
= ioprio_best(req
->ioprio
, bio_prio(bio
));
1308 drive_stat_acct(req
, 0);
1313 * attempt_plug_merge - try to merge with %current's plugged list
1314 * @q: request_queue new bio is being queued at
1315 * @bio: new bio being queued
1316 * @request_count: out parameter for number of traversed plugged requests
1318 * Determine whether @bio being queued on @q can be merged with a request
1319 * on %current's plugged list. Returns %true if merge was successful,
1322 * Plugging coalesces IOs from the same issuer for the same purpose without
1323 * going through @q->queue_lock. As such it's more of an issuing mechanism
1324 * than scheduling, and the request, while may have elvpriv data, is not
1325 * added on the elevator at this point. In addition, we don't have
1326 * reliable access to the elevator outside queue lock. Only check basic
1327 * merging parameters without querying the elevator.
1329 static bool attempt_plug_merge(struct request_queue
*q
, struct bio
*bio
,
1330 unsigned int *request_count
)
1332 struct blk_plug
*plug
;
1336 plug
= current
->plug
;
1341 list_for_each_entry_reverse(rq
, &plug
->list
, queuelist
) {
1346 if (rq
->q
!= q
|| !blk_rq_merge_ok(rq
, bio
))
1349 el_ret
= blk_try_merge(rq
, bio
);
1350 if (el_ret
== ELEVATOR_BACK_MERGE
) {
1351 ret
= bio_attempt_back_merge(q
, rq
, bio
);
1354 } else if (el_ret
== ELEVATOR_FRONT_MERGE
) {
1355 ret
= bio_attempt_front_merge(q
, rq
, bio
);
1364 void init_request_from_bio(struct request
*req
, struct bio
*bio
)
1366 req
->cmd_type
= REQ_TYPE_FS
;
1368 req
->cmd_flags
|= bio
->bi_rw
& REQ_COMMON_MASK
;
1369 if (bio
->bi_rw
& REQ_RAHEAD
)
1370 req
->cmd_flags
|= REQ_FAILFAST_MASK
;
1373 req
->__sector
= bio
->bi_sector
;
1374 req
->ioprio
= bio_prio(bio
);
1375 blk_rq_bio_prep(req
->q
, req
, bio
);
1378 void blk_queue_bio(struct request_queue
*q
, struct bio
*bio
)
1380 const bool sync
= !!(bio
->bi_rw
& REQ_SYNC
);
1381 struct blk_plug
*plug
;
1382 int el_ret
, rw_flags
, where
= ELEVATOR_INSERT_SORT
;
1383 struct request
*req
;
1384 unsigned int request_count
= 0;
1387 * low level driver can indicate that it wants pages above a
1388 * certain limit bounced to low memory (ie for highmem, or even
1389 * ISA dma in theory)
1391 blk_queue_bounce(q
, &bio
);
1393 if (bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
)) {
1394 spin_lock_irq(q
->queue_lock
);
1395 where
= ELEVATOR_INSERT_FLUSH
;
1400 * Check if we can merge with the plugged list before grabbing
1403 if (attempt_plug_merge(q
, bio
, &request_count
))
1406 spin_lock_irq(q
->queue_lock
);
1408 el_ret
= elv_merge(q
, &req
, bio
);
1409 if (el_ret
== ELEVATOR_BACK_MERGE
) {
1410 if (bio_attempt_back_merge(q
, req
, bio
)) {
1411 elv_bio_merged(q
, req
, bio
);
1412 if (!attempt_back_merge(q
, req
))
1413 elv_merged_request(q
, req
, el_ret
);
1416 } else if (el_ret
== ELEVATOR_FRONT_MERGE
) {
1417 if (bio_attempt_front_merge(q
, req
, bio
)) {
1418 elv_bio_merged(q
, req
, bio
);
1419 if (!attempt_front_merge(q
, req
))
1420 elv_merged_request(q
, req
, el_ret
);
1427 * This sync check and mask will be re-done in init_request_from_bio(),
1428 * but we need to set it earlier to expose the sync flag to the
1429 * rq allocator and io schedulers.
1431 rw_flags
= bio_data_dir(bio
);
1433 rw_flags
|= REQ_SYNC
;
1436 * Grab a free request. This is might sleep but can not fail.
1437 * Returns with the queue unlocked.
1439 req
= get_request_wait(q
, rw_flags
, bio
);
1440 if (unlikely(!req
)) {
1441 bio_endio(bio
, -ENODEV
); /* @q is dead */
1446 * After dropping the lock and possibly sleeping here, our request
1447 * may now be mergeable after it had proven unmergeable (above).
1448 * We don't worry about that case for efficiency. It won't happen
1449 * often, and the elevators are able to handle it.
1451 init_request_from_bio(req
, bio
);
1453 if (test_bit(QUEUE_FLAG_SAME_COMP
, &q
->queue_flags
))
1454 req
->cpu
= raw_smp_processor_id();
1456 plug
= current
->plug
;
1459 * If this is the first request added after a plug, fire
1460 * of a plug trace. If others have been added before, check
1461 * if we have multiple devices in this plug. If so, make a
1462 * note to sort the list before dispatch.
1464 if (list_empty(&plug
->list
))
1465 trace_block_plug(q
);
1467 if (!plug
->should_sort
) {
1468 struct request
*__rq
;
1470 __rq
= list_entry_rq(plug
->list
.prev
);
1472 plug
->should_sort
= 1;
1474 if (request_count
>= BLK_MAX_REQUEST_COUNT
) {
1475 blk_flush_plug_list(plug
, false);
1476 trace_block_plug(q
);
1479 list_add_tail(&req
->queuelist
, &plug
->list
);
1480 drive_stat_acct(req
, 1);
1482 spin_lock_irq(q
->queue_lock
);
1483 add_acct_request(q
, req
, where
);
1486 spin_unlock_irq(q
->queue_lock
);
1489 EXPORT_SYMBOL_GPL(blk_queue_bio
); /* for device mapper only */
1492 * If bio->bi_dev is a partition, remap the location
1494 static inline void blk_partition_remap(struct bio
*bio
)
1496 struct block_device
*bdev
= bio
->bi_bdev
;
1498 if (bio_sectors(bio
) && bdev
!= bdev
->bd_contains
) {
1499 struct hd_struct
*p
= bdev
->bd_part
;
1501 bio
->bi_sector
+= p
->start_sect
;
1502 bio
->bi_bdev
= bdev
->bd_contains
;
1504 trace_block_bio_remap(bdev_get_queue(bio
->bi_bdev
), bio
,
1506 bio
->bi_sector
- p
->start_sect
);
1510 static void handle_bad_sector(struct bio
*bio
)
1512 char b
[BDEVNAME_SIZE
];
1514 printk(KERN_INFO
"attempt to access beyond end of device\n");
1515 printk(KERN_INFO
"%s: rw=%ld, want=%Lu, limit=%Lu\n",
1516 bdevname(bio
->bi_bdev
, b
),
1518 (unsigned long long)bio
->bi_sector
+ bio_sectors(bio
),
1519 (long long)(i_size_read(bio
->bi_bdev
->bd_inode
) >> 9));
1521 set_bit(BIO_EOF
, &bio
->bi_flags
);
1524 #ifdef CONFIG_FAIL_MAKE_REQUEST
1526 static DECLARE_FAULT_ATTR(fail_make_request
);
1528 static int __init
setup_fail_make_request(char *str
)
1530 return setup_fault_attr(&fail_make_request
, str
);
1532 __setup("fail_make_request=", setup_fail_make_request
);
1534 static bool should_fail_request(struct hd_struct
*part
, unsigned int bytes
)
1536 return part
->make_it_fail
&& should_fail(&fail_make_request
, bytes
);
1539 static int __init
fail_make_request_debugfs(void)
1541 struct dentry
*dir
= fault_create_debugfs_attr("fail_make_request",
1542 NULL
, &fail_make_request
);
1544 return IS_ERR(dir
) ? PTR_ERR(dir
) : 0;
1547 late_initcall(fail_make_request_debugfs
);
1549 #else /* CONFIG_FAIL_MAKE_REQUEST */
1551 static inline bool should_fail_request(struct hd_struct
*part
,
1557 #endif /* CONFIG_FAIL_MAKE_REQUEST */
1560 * Check whether this bio extends beyond the end of the device.
1562 static inline int bio_check_eod(struct bio
*bio
, unsigned int nr_sectors
)
1569 /* Test device or partition size, when known. */
1570 maxsector
= i_size_read(bio
->bi_bdev
->bd_inode
) >> 9;
1572 sector_t sector
= bio
->bi_sector
;
1574 if (maxsector
< nr_sectors
|| maxsector
- nr_sectors
< sector
) {
1576 * This may well happen - the kernel calls bread()
1577 * without checking the size of the device, e.g., when
1578 * mounting a device.
1580 handle_bad_sector(bio
);
1588 static noinline_for_stack
bool
1589 generic_make_request_checks(struct bio
*bio
)
1591 struct request_queue
*q
;
1592 int nr_sectors
= bio_sectors(bio
);
1594 char b
[BDEVNAME_SIZE
];
1595 struct hd_struct
*part
;
1599 if (bio_check_eod(bio
, nr_sectors
))
1602 q
= bdev_get_queue(bio
->bi_bdev
);
1605 "generic_make_request: Trying to access "
1606 "nonexistent block-device %s (%Lu)\n",
1607 bdevname(bio
->bi_bdev
, b
),
1608 (long long) bio
->bi_sector
);
1612 if (unlikely(!(bio
->bi_rw
& REQ_DISCARD
) &&
1613 nr_sectors
> queue_max_hw_sectors(q
))) {
1614 printk(KERN_ERR
"bio too big device %s (%u > %u)\n",
1615 bdevname(bio
->bi_bdev
, b
),
1617 queue_max_hw_sectors(q
));
1621 part
= bio
->bi_bdev
->bd_part
;
1622 if (should_fail_request(part
, bio
->bi_size
) ||
1623 should_fail_request(&part_to_disk(part
)->part0
,
1628 * If this device has partitions, remap block n
1629 * of partition p to block n+start(p) of the disk.
1631 blk_partition_remap(bio
);
1633 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
))
1636 if (bio_check_eod(bio
, nr_sectors
))
1640 * Filter flush bio's early so that make_request based
1641 * drivers without flush support don't have to worry
1644 if ((bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
)) && !q
->flush_flags
) {
1645 bio
->bi_rw
&= ~(REQ_FLUSH
| REQ_FUA
);
1652 if ((bio
->bi_rw
& REQ_DISCARD
) &&
1653 (!blk_queue_discard(q
) ||
1654 ((bio
->bi_rw
& REQ_SECURE
) &&
1655 !blk_queue_secdiscard(q
)))) {
1660 if (blk_throtl_bio(q
, bio
))
1661 return false; /* throttled, will be resubmitted later */
1663 trace_block_bio_queue(q
, bio
);
1667 bio_endio(bio
, err
);
1672 * generic_make_request - hand a buffer to its device driver for I/O
1673 * @bio: The bio describing the location in memory and on the device.
1675 * generic_make_request() is used to make I/O requests of block
1676 * devices. It is passed a &struct bio, which describes the I/O that needs
1679 * generic_make_request() does not return any status. The
1680 * success/failure status of the request, along with notification of
1681 * completion, is delivered asynchronously through the bio->bi_end_io
1682 * function described (one day) else where.
1684 * The caller of generic_make_request must make sure that bi_io_vec
1685 * are set to describe the memory buffer, and that bi_dev and bi_sector are
1686 * set to describe the device address, and the
1687 * bi_end_io and optionally bi_private are set to describe how
1688 * completion notification should be signaled.
1690 * generic_make_request and the drivers it calls may use bi_next if this
1691 * bio happens to be merged with someone else, and may resubmit the bio to
1692 * a lower device by calling into generic_make_request recursively, which
1693 * means the bio should NOT be touched after the call to ->make_request_fn.
1695 void generic_make_request(struct bio
*bio
)
1697 struct bio_list bio_list_on_stack
;
1699 if (!generic_make_request_checks(bio
))
1703 * We only want one ->make_request_fn to be active at a time, else
1704 * stack usage with stacked devices could be a problem. So use
1705 * current->bio_list to keep a list of requests submited by a
1706 * make_request_fn function. current->bio_list is also used as a
1707 * flag to say if generic_make_request is currently active in this
1708 * task or not. If it is NULL, then no make_request is active. If
1709 * it is non-NULL, then a make_request is active, and new requests
1710 * should be added at the tail
1712 if (current
->bio_list
) {
1713 bio_list_add(current
->bio_list
, bio
);
1717 /* following loop may be a bit non-obvious, and so deserves some
1719 * Before entering the loop, bio->bi_next is NULL (as all callers
1720 * ensure that) so we have a list with a single bio.
1721 * We pretend that we have just taken it off a longer list, so
1722 * we assign bio_list to a pointer to the bio_list_on_stack,
1723 * thus initialising the bio_list of new bios to be
1724 * added. ->make_request() may indeed add some more bios
1725 * through a recursive call to generic_make_request. If it
1726 * did, we find a non-NULL value in bio_list and re-enter the loop
1727 * from the top. In this case we really did just take the bio
1728 * of the top of the list (no pretending) and so remove it from
1729 * bio_list, and call into ->make_request() again.
1731 BUG_ON(bio
->bi_next
);
1732 bio_list_init(&bio_list_on_stack
);
1733 current
->bio_list
= &bio_list_on_stack
;
1735 struct request_queue
*q
= bdev_get_queue(bio
->bi_bdev
);
1737 q
->make_request_fn(q
, bio
);
1739 bio
= bio_list_pop(current
->bio_list
);
1741 current
->bio_list
= NULL
; /* deactivate */
1743 EXPORT_SYMBOL(generic_make_request
);
1746 * submit_bio - submit a bio to the block device layer for I/O
1747 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
1748 * @bio: The &struct bio which describes the I/O
1750 * submit_bio() is very similar in purpose to generic_make_request(), and
1751 * uses that function to do most of the work. Both are fairly rough
1752 * interfaces; @bio must be presetup and ready for I/O.
1755 void submit_bio(int rw
, struct bio
*bio
)
1757 int count
= bio_sectors(bio
);
1762 * If it's a regular read/write or a barrier with data attached,
1763 * go through the normal accounting stuff before submission.
1765 if (bio_has_data(bio
) && !(rw
& REQ_DISCARD
)) {
1767 count_vm_events(PGPGOUT
, count
);
1769 task_io_account_read(bio
->bi_size
);
1770 count_vm_events(PGPGIN
, count
);
1773 if (unlikely(block_dump
)) {
1774 char b
[BDEVNAME_SIZE
];
1775 printk(KERN_DEBUG
"%s(%d): %s block %Lu on %s (%u sectors)\n",
1776 current
->comm
, task_pid_nr(current
),
1777 (rw
& WRITE
) ? "WRITE" : "READ",
1778 (unsigned long long)bio
->bi_sector
,
1779 bdevname(bio
->bi_bdev
, b
),
1784 generic_make_request(bio
);
1786 EXPORT_SYMBOL(submit_bio
);
1789 * blk_rq_check_limits - Helper function to check a request for the queue limit
1791 * @rq: the request being checked
1794 * @rq may have been made based on weaker limitations of upper-level queues
1795 * in request stacking drivers, and it may violate the limitation of @q.
1796 * Since the block layer and the underlying device driver trust @rq
1797 * after it is inserted to @q, it should be checked against @q before
1798 * the insertion using this generic function.
1800 * This function should also be useful for request stacking drivers
1801 * in some cases below, so export this function.
1802 * Request stacking drivers like request-based dm may change the queue
1803 * limits while requests are in the queue (e.g. dm's table swapping).
1804 * Such request stacking drivers should check those requests agaist
1805 * the new queue limits again when they dispatch those requests,
1806 * although such checkings are also done against the old queue limits
1807 * when submitting requests.
1809 int blk_rq_check_limits(struct request_queue
*q
, struct request
*rq
)
1811 if (rq
->cmd_flags
& REQ_DISCARD
)
1814 if (blk_rq_sectors(rq
) > queue_max_sectors(q
) ||
1815 blk_rq_bytes(rq
) > queue_max_hw_sectors(q
) << 9) {
1816 printk(KERN_ERR
"%s: over max size limit.\n", __func__
);
1821 * queue's settings related to segment counting like q->bounce_pfn
1822 * may differ from that of other stacking queues.
1823 * Recalculate it to check the request correctly on this queue's
1826 blk_recalc_rq_segments(rq
);
1827 if (rq
->nr_phys_segments
> queue_max_segments(q
)) {
1828 printk(KERN_ERR
"%s: over max segments limit.\n", __func__
);
1834 EXPORT_SYMBOL_GPL(blk_rq_check_limits
);
1837 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
1838 * @q: the queue to submit the request
1839 * @rq: the request being queued
1841 int blk_insert_cloned_request(struct request_queue
*q
, struct request
*rq
)
1843 unsigned long flags
;
1844 int where
= ELEVATOR_INSERT_BACK
;
1846 if (blk_rq_check_limits(q
, rq
))
1850 should_fail_request(&rq
->rq_disk
->part0
, blk_rq_bytes(rq
)))
1853 spin_lock_irqsave(q
->queue_lock
, flags
);
1854 if (unlikely(blk_queue_dead(q
))) {
1855 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1860 * Submitting request must be dequeued before calling this function
1861 * because it will be linked to another request_queue
1863 BUG_ON(blk_queued_rq(rq
));
1865 if (rq
->cmd_flags
& (REQ_FLUSH
|REQ_FUA
))
1866 where
= ELEVATOR_INSERT_FLUSH
;
1868 add_acct_request(q
, rq
, where
);
1869 if (where
== ELEVATOR_INSERT_FLUSH
)
1871 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1875 EXPORT_SYMBOL_GPL(blk_insert_cloned_request
);
1878 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
1879 * @rq: request to examine
1882 * A request could be merge of IOs which require different failure
1883 * handling. This function determines the number of bytes which
1884 * can be failed from the beginning of the request without
1885 * crossing into area which need to be retried further.
1888 * The number of bytes to fail.
1891 * queue_lock must be held.
1893 unsigned int blk_rq_err_bytes(const struct request
*rq
)
1895 unsigned int ff
= rq
->cmd_flags
& REQ_FAILFAST_MASK
;
1896 unsigned int bytes
= 0;
1899 if (!(rq
->cmd_flags
& REQ_MIXED_MERGE
))
1900 return blk_rq_bytes(rq
);
1903 * Currently the only 'mixing' which can happen is between
1904 * different fastfail types. We can safely fail portions
1905 * which have all the failfast bits that the first one has -
1906 * the ones which are at least as eager to fail as the first
1909 for (bio
= rq
->bio
; bio
; bio
= bio
->bi_next
) {
1910 if ((bio
->bi_rw
& ff
) != ff
)
1912 bytes
+= bio
->bi_size
;
1915 /* this could lead to infinite loop */
1916 BUG_ON(blk_rq_bytes(rq
) && !bytes
);
1919 EXPORT_SYMBOL_GPL(blk_rq_err_bytes
);
1921 static void blk_account_io_completion(struct request
*req
, unsigned int bytes
)
1923 if (blk_do_io_stat(req
)) {
1924 const int rw
= rq_data_dir(req
);
1925 struct hd_struct
*part
;
1928 cpu
= part_stat_lock();
1930 part_stat_add(cpu
, part
, sectors
[rw
], bytes
>> 9);
1935 static void blk_account_io_done(struct request
*req
)
1938 * Account IO completion. flush_rq isn't accounted as a
1939 * normal IO on queueing nor completion. Accounting the
1940 * containing request is enough.
1942 if (blk_do_io_stat(req
) && !(req
->cmd_flags
& REQ_FLUSH_SEQ
)) {
1943 unsigned long duration
= jiffies
- req
->start_time
;
1944 const int rw
= rq_data_dir(req
);
1945 struct hd_struct
*part
;
1948 cpu
= part_stat_lock();
1951 part_stat_inc(cpu
, part
, ios
[rw
]);
1952 part_stat_add(cpu
, part
, ticks
[rw
], duration
);
1953 part_round_stats(cpu
, part
);
1954 part_dec_in_flight(part
, rw
);
1956 hd_struct_put(part
);
1962 * blk_peek_request - peek at the top of a request queue
1963 * @q: request queue to peek at
1966 * Return the request at the top of @q. The returned request
1967 * should be started using blk_start_request() before LLD starts
1971 * Pointer to the request at the top of @q if available. Null
1975 * queue_lock must be held.
1977 struct request
*blk_peek_request(struct request_queue
*q
)
1982 while ((rq
= __elv_next_request(q
)) != NULL
) {
1983 if (!(rq
->cmd_flags
& REQ_STARTED
)) {
1985 * This is the first time the device driver
1986 * sees this request (possibly after
1987 * requeueing). Notify IO scheduler.
1989 if (rq
->cmd_flags
& REQ_SORTED
)
1990 elv_activate_rq(q
, rq
);
1993 * just mark as started even if we don't start
1994 * it, a request that has been delayed should
1995 * not be passed by new incoming requests
1997 rq
->cmd_flags
|= REQ_STARTED
;
1998 trace_block_rq_issue(q
, rq
);
2001 if (!q
->boundary_rq
|| q
->boundary_rq
== rq
) {
2002 q
->end_sector
= rq_end_sector(rq
);
2003 q
->boundary_rq
= NULL
;
2006 if (rq
->cmd_flags
& REQ_DONTPREP
)
2009 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
2011 * make sure space for the drain appears we
2012 * know we can do this because max_hw_segments
2013 * has been adjusted to be one fewer than the
2016 rq
->nr_phys_segments
++;
2022 ret
= q
->prep_rq_fn(q
, rq
);
2023 if (ret
== BLKPREP_OK
) {
2025 } else if (ret
== BLKPREP_DEFER
) {
2027 * the request may have been (partially) prepped.
2028 * we need to keep this request in the front to
2029 * avoid resource deadlock. REQ_STARTED will
2030 * prevent other fs requests from passing this one.
2032 if (q
->dma_drain_size
&& blk_rq_bytes(rq
) &&
2033 !(rq
->cmd_flags
& REQ_DONTPREP
)) {
2035 * remove the space for the drain we added
2036 * so that we don't add it again
2038 --rq
->nr_phys_segments
;
2043 } else if (ret
== BLKPREP_KILL
) {
2044 rq
->cmd_flags
|= REQ_QUIET
;
2046 * Mark this request as started so we don't trigger
2047 * any debug logic in the end I/O path.
2049 blk_start_request(rq
);
2050 __blk_end_request_all(rq
, -EIO
);
2052 printk(KERN_ERR
"%s: bad return=%d\n", __func__
, ret
);
2059 EXPORT_SYMBOL(blk_peek_request
);
2061 void blk_dequeue_request(struct request
*rq
)
2063 struct request_queue
*q
= rq
->q
;
2065 BUG_ON(list_empty(&rq
->queuelist
));
2066 BUG_ON(ELV_ON_HASH(rq
));
2068 list_del_init(&rq
->queuelist
);
2071 * the time frame between a request being removed from the lists
2072 * and to it is freed is accounted as io that is in progress at
2075 if (blk_account_rq(rq
)) {
2076 q
->in_flight
[rq_is_sync(rq
)]++;
2077 set_io_start_time_ns(rq
);
2082 * blk_start_request - start request processing on the driver
2083 * @req: request to dequeue
2086 * Dequeue @req and start timeout timer on it. This hands off the
2087 * request to the driver.
2089 * Block internal functions which don't want to start timer should
2090 * call blk_dequeue_request().
2093 * queue_lock must be held.
2095 void blk_start_request(struct request
*req
)
2097 blk_dequeue_request(req
);
2100 * We are now handing the request to the hardware, initialize
2101 * resid_len to full count and add the timeout handler.
2103 req
->resid_len
= blk_rq_bytes(req
);
2104 if (unlikely(blk_bidi_rq(req
)))
2105 req
->next_rq
->resid_len
= blk_rq_bytes(req
->next_rq
);
2109 EXPORT_SYMBOL(blk_start_request
);
2112 * blk_fetch_request - fetch a request from a request queue
2113 * @q: request queue to fetch a request from
2116 * Return the request at the top of @q. The request is started on
2117 * return and LLD can start processing it immediately.
2120 * Pointer to the request at the top of @q if available. Null
2124 * queue_lock must be held.
2126 struct request
*blk_fetch_request(struct request_queue
*q
)
2130 rq
= blk_peek_request(q
);
2132 blk_start_request(rq
);
2135 EXPORT_SYMBOL(blk_fetch_request
);
2138 * blk_update_request - Special helper function for request stacking drivers
2139 * @req: the request being processed
2140 * @error: %0 for success, < %0 for error
2141 * @nr_bytes: number of bytes to complete @req
2144 * Ends I/O on a number of bytes attached to @req, but doesn't complete
2145 * the request structure even if @req doesn't have leftover.
2146 * If @req has leftover, sets it up for the next range of segments.
2148 * This special helper function is only for request stacking drivers
2149 * (e.g. request-based dm) so that they can handle partial completion.
2150 * Actual device drivers should use blk_end_request instead.
2152 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
2153 * %false return from this function.
2156 * %false - this request doesn't have any more data
2157 * %true - this request has more data
2159 bool blk_update_request(struct request
*req
, int error
, unsigned int nr_bytes
)
2161 int total_bytes
, bio_nbytes
, next_idx
= 0;
2167 trace_block_rq_complete(req
->q
, req
);
2170 * For fs requests, rq is just carrier of independent bio's
2171 * and each partial completion should be handled separately.
2172 * Reset per-request error on each partial completion.
2174 * TODO: tj: This is too subtle. It would be better to let
2175 * low level drivers do what they see fit.
2177 if (req
->cmd_type
== REQ_TYPE_FS
)
2180 if (error
&& req
->cmd_type
== REQ_TYPE_FS
&&
2181 !(req
->cmd_flags
& REQ_QUIET
)) {
2186 error_type
= "recoverable transport";
2189 error_type
= "critical target";
2192 error_type
= "critical nexus";
2199 printk(KERN_ERR
"end_request: %s error, dev %s, sector %llu\n",
2200 error_type
, req
->rq_disk
? req
->rq_disk
->disk_name
: "?",
2201 (unsigned long long)blk_rq_pos(req
));
2204 blk_account_io_completion(req
, nr_bytes
);
2206 total_bytes
= bio_nbytes
= 0;
2207 while ((bio
= req
->bio
) != NULL
) {
2210 if (nr_bytes
>= bio
->bi_size
) {
2211 req
->bio
= bio
->bi_next
;
2212 nbytes
= bio
->bi_size
;
2213 req_bio_endio(req
, bio
, nbytes
, error
);
2217 int idx
= bio
->bi_idx
+ next_idx
;
2219 if (unlikely(idx
>= bio
->bi_vcnt
)) {
2220 blk_dump_rq_flags(req
, "__end_that");
2221 printk(KERN_ERR
"%s: bio idx %d >= vcnt %d\n",
2222 __func__
, idx
, bio
->bi_vcnt
);
2226 nbytes
= bio_iovec_idx(bio
, idx
)->bv_len
;
2227 BIO_BUG_ON(nbytes
> bio
->bi_size
);
2230 * not a complete bvec done
2232 if (unlikely(nbytes
> nr_bytes
)) {
2233 bio_nbytes
+= nr_bytes
;
2234 total_bytes
+= nr_bytes
;
2239 * advance to the next vector
2242 bio_nbytes
+= nbytes
;
2245 total_bytes
+= nbytes
;
2251 * end more in this run, or just return 'not-done'
2253 if (unlikely(nr_bytes
<= 0))
2263 * Reset counters so that the request stacking driver
2264 * can find how many bytes remain in the request
2267 req
->__data_len
= 0;
2272 * if the request wasn't completed, update state
2275 req_bio_endio(req
, bio
, bio_nbytes
, error
);
2276 bio
->bi_idx
+= next_idx
;
2277 bio_iovec(bio
)->bv_offset
+= nr_bytes
;
2278 bio_iovec(bio
)->bv_len
-= nr_bytes
;
2281 req
->__data_len
-= total_bytes
;
2282 req
->buffer
= bio_data(req
->bio
);
2284 /* update sector only for requests with clear definition of sector */
2285 if (req
->cmd_type
== REQ_TYPE_FS
|| (req
->cmd_flags
& REQ_DISCARD
))
2286 req
->__sector
+= total_bytes
>> 9;
2288 /* mixed attributes always follow the first bio */
2289 if (req
->cmd_flags
& REQ_MIXED_MERGE
) {
2290 req
->cmd_flags
&= ~REQ_FAILFAST_MASK
;
2291 req
->cmd_flags
|= req
->bio
->bi_rw
& REQ_FAILFAST_MASK
;
2295 * If total number of sectors is less than the first segment
2296 * size, something has gone terribly wrong.
2298 if (blk_rq_bytes(req
) < blk_rq_cur_bytes(req
)) {
2299 blk_dump_rq_flags(req
, "request botched");
2300 req
->__data_len
= blk_rq_cur_bytes(req
);
2303 /* recalculate the number of segments */
2304 blk_recalc_rq_segments(req
);
2308 EXPORT_SYMBOL_GPL(blk_update_request
);
2310 static bool blk_update_bidi_request(struct request
*rq
, int error
,
2311 unsigned int nr_bytes
,
2312 unsigned int bidi_bytes
)
2314 if (blk_update_request(rq
, error
, nr_bytes
))
2317 /* Bidi request must be completed as a whole */
2318 if (unlikely(blk_bidi_rq(rq
)) &&
2319 blk_update_request(rq
->next_rq
, error
, bidi_bytes
))
2322 if (blk_queue_add_random(rq
->q
))
2323 add_disk_randomness(rq
->rq_disk
);
2329 * blk_unprep_request - unprepare a request
2332 * This function makes a request ready for complete resubmission (or
2333 * completion). It happens only after all error handling is complete,
2334 * so represents the appropriate moment to deallocate any resources
2335 * that were allocated to the request in the prep_rq_fn. The queue
2336 * lock is held when calling this.
2338 void blk_unprep_request(struct request
*req
)
2340 struct request_queue
*q
= req
->q
;
2342 req
->cmd_flags
&= ~REQ_DONTPREP
;
2343 if (q
->unprep_rq_fn
)
2344 q
->unprep_rq_fn(q
, req
);
2346 EXPORT_SYMBOL_GPL(blk_unprep_request
);
2349 * queue lock must be held
2351 static void blk_finish_request(struct request
*req
, int error
)
2353 if (blk_rq_tagged(req
))
2354 blk_queue_end_tag(req
->q
, req
);
2356 BUG_ON(blk_queued_rq(req
));
2358 if (unlikely(laptop_mode
) && req
->cmd_type
== REQ_TYPE_FS
)
2359 laptop_io_completion(&req
->q
->backing_dev_info
);
2361 blk_delete_timer(req
);
2363 if (req
->cmd_flags
& REQ_DONTPREP
)
2364 blk_unprep_request(req
);
2367 blk_account_io_done(req
);
2370 req
->end_io(req
, error
);
2372 if (blk_bidi_rq(req
))
2373 __blk_put_request(req
->next_rq
->q
, req
->next_rq
);
2375 __blk_put_request(req
->q
, req
);
2380 * blk_end_bidi_request - Complete a bidi request
2381 * @rq: the request to complete
2382 * @error: %0 for success, < %0 for error
2383 * @nr_bytes: number of bytes to complete @rq
2384 * @bidi_bytes: number of bytes to complete @rq->next_rq
2387 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2388 * Drivers that supports bidi can safely call this member for any
2389 * type of request, bidi or uni. In the later case @bidi_bytes is
2393 * %false - we are done with this request
2394 * %true - still buffers pending for this request
2396 static bool blk_end_bidi_request(struct request
*rq
, int error
,
2397 unsigned int nr_bytes
, unsigned int bidi_bytes
)
2399 struct request_queue
*q
= rq
->q
;
2400 unsigned long flags
;
2402 if (blk_update_bidi_request(rq
, error
, nr_bytes
, bidi_bytes
))
2405 spin_lock_irqsave(q
->queue_lock
, flags
);
2406 blk_finish_request(rq
, error
);
2407 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2413 * __blk_end_bidi_request - Complete a bidi request with queue lock held
2414 * @rq: the request to complete
2415 * @error: %0 for success, < %0 for error
2416 * @nr_bytes: number of bytes to complete @rq
2417 * @bidi_bytes: number of bytes to complete @rq->next_rq
2420 * Identical to blk_end_bidi_request() except that queue lock is
2421 * assumed to be locked on entry and remains so on return.
2424 * %false - we are done with this request
2425 * %true - still buffers pending for this request
2427 bool __blk_end_bidi_request(struct request
*rq
, int error
,
2428 unsigned int nr_bytes
, unsigned int bidi_bytes
)
2430 if (blk_update_bidi_request(rq
, error
, nr_bytes
, bidi_bytes
))
2433 blk_finish_request(rq
, error
);
2439 * blk_end_request - Helper function for drivers to complete the request.
2440 * @rq: the request being processed
2441 * @error: %0 for success, < %0 for error
2442 * @nr_bytes: number of bytes to complete
2445 * Ends I/O on a number of bytes attached to @rq.
2446 * If @rq has leftover, sets it up for the next range of segments.
2449 * %false - we are done with this request
2450 * %true - still buffers pending for this request
2452 bool blk_end_request(struct request
*rq
, int error
, unsigned int nr_bytes
)
2454 return blk_end_bidi_request(rq
, error
, nr_bytes
, 0);
2456 EXPORT_SYMBOL(blk_end_request
);
2459 * blk_end_request_all - Helper function for drives to finish the request.
2460 * @rq: the request to finish
2461 * @error: %0 for success, < %0 for error
2464 * Completely finish @rq.
2466 void blk_end_request_all(struct request
*rq
, int error
)
2469 unsigned int bidi_bytes
= 0;
2471 if (unlikely(blk_bidi_rq(rq
)))
2472 bidi_bytes
= blk_rq_bytes(rq
->next_rq
);
2474 pending
= blk_end_bidi_request(rq
, error
, blk_rq_bytes(rq
), bidi_bytes
);
2477 EXPORT_SYMBOL(blk_end_request_all
);
2480 * blk_end_request_cur - Helper function to finish the current request chunk.
2481 * @rq: the request to finish the current chunk for
2482 * @error: %0 for success, < %0 for error
2485 * Complete the current consecutively mapped chunk from @rq.
2488 * %false - we are done with this request
2489 * %true - still buffers pending for this request
2491 bool blk_end_request_cur(struct request
*rq
, int error
)
2493 return blk_end_request(rq
, error
, blk_rq_cur_bytes(rq
));
2495 EXPORT_SYMBOL(blk_end_request_cur
);
2498 * blk_end_request_err - Finish a request till the next failure boundary.
2499 * @rq: the request to finish till the next failure boundary for
2500 * @error: must be negative errno
2503 * Complete @rq till the next failure boundary.
2506 * %false - we are done with this request
2507 * %true - still buffers pending for this request
2509 bool blk_end_request_err(struct request
*rq
, int error
)
2511 WARN_ON(error
>= 0);
2512 return blk_end_request(rq
, error
, blk_rq_err_bytes(rq
));
2514 EXPORT_SYMBOL_GPL(blk_end_request_err
);
2517 * __blk_end_request - Helper function for drivers to complete the request.
2518 * @rq: the request being processed
2519 * @error: %0 for success, < %0 for error
2520 * @nr_bytes: number of bytes to complete
2523 * Must be called with queue lock held unlike blk_end_request().
2526 * %false - we are done with this request
2527 * %true - still buffers pending for this request
2529 bool __blk_end_request(struct request
*rq
, int error
, unsigned int nr_bytes
)
2531 return __blk_end_bidi_request(rq
, error
, nr_bytes
, 0);
2533 EXPORT_SYMBOL(__blk_end_request
);
2536 * __blk_end_request_all - Helper function for drives to finish the request.
2537 * @rq: the request to finish
2538 * @error: %0 for success, < %0 for error
2541 * Completely finish @rq. Must be called with queue lock held.
2543 void __blk_end_request_all(struct request
*rq
, int error
)
2546 unsigned int bidi_bytes
= 0;
2548 if (unlikely(blk_bidi_rq(rq
)))
2549 bidi_bytes
= blk_rq_bytes(rq
->next_rq
);
2551 pending
= __blk_end_bidi_request(rq
, error
, blk_rq_bytes(rq
), bidi_bytes
);
2554 EXPORT_SYMBOL(__blk_end_request_all
);
2557 * __blk_end_request_cur - Helper function to finish the current request chunk.
2558 * @rq: the request to finish the current chunk for
2559 * @error: %0 for success, < %0 for error
2562 * Complete the current consecutively mapped chunk from @rq. Must
2563 * be called with queue lock held.
2566 * %false - we are done with this request
2567 * %true - still buffers pending for this request
2569 bool __blk_end_request_cur(struct request
*rq
, int error
)
2571 return __blk_end_request(rq
, error
, blk_rq_cur_bytes(rq
));
2573 EXPORT_SYMBOL(__blk_end_request_cur
);
2576 * __blk_end_request_err - Finish a request till the next failure boundary.
2577 * @rq: the request to finish till the next failure boundary for
2578 * @error: must be negative errno
2581 * Complete @rq till the next failure boundary. Must be called
2582 * with queue lock held.
2585 * %false - we are done with this request
2586 * %true - still buffers pending for this request
2588 bool __blk_end_request_err(struct request
*rq
, int error
)
2590 WARN_ON(error
>= 0);
2591 return __blk_end_request(rq
, error
, blk_rq_err_bytes(rq
));
2593 EXPORT_SYMBOL_GPL(__blk_end_request_err
);
2595 void blk_rq_bio_prep(struct request_queue
*q
, struct request
*rq
,
2598 /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */
2599 rq
->cmd_flags
|= bio
->bi_rw
& REQ_WRITE
;
2601 if (bio_has_data(bio
)) {
2602 rq
->nr_phys_segments
= bio_phys_segments(q
, bio
);
2603 rq
->buffer
= bio_data(bio
);
2605 rq
->__data_len
= bio
->bi_size
;
2606 rq
->bio
= rq
->biotail
= bio
;
2609 rq
->rq_disk
= bio
->bi_bdev
->bd_disk
;
2612 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
2614 * rq_flush_dcache_pages - Helper function to flush all pages in a request
2615 * @rq: the request to be flushed
2618 * Flush all pages in @rq.
2620 void rq_flush_dcache_pages(struct request
*rq
)
2622 struct req_iterator iter
;
2623 struct bio_vec
*bvec
;
2625 rq_for_each_segment(bvec
, rq
, iter
)
2626 flush_dcache_page(bvec
->bv_page
);
2628 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages
);
2632 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
2633 * @q : the queue of the device being checked
2636 * Check if underlying low-level drivers of a device are busy.
2637 * If the drivers want to export their busy state, they must set own
2638 * exporting function using blk_queue_lld_busy() first.
2640 * Basically, this function is used only by request stacking drivers
2641 * to stop dispatching requests to underlying devices when underlying
2642 * devices are busy. This behavior helps more I/O merging on the queue
2643 * of the request stacking driver and prevents I/O throughput regression
2644 * on burst I/O load.
2647 * 0 - Not busy (The request stacking driver should dispatch request)
2648 * 1 - Busy (The request stacking driver should stop dispatching request)
2650 int blk_lld_busy(struct request_queue
*q
)
2653 return q
->lld_busy_fn(q
);
2657 EXPORT_SYMBOL_GPL(blk_lld_busy
);
2660 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
2661 * @rq: the clone request to be cleaned up
2664 * Free all bios in @rq for a cloned request.
2666 void blk_rq_unprep_clone(struct request
*rq
)
2670 while ((bio
= rq
->bio
) != NULL
) {
2671 rq
->bio
= bio
->bi_next
;
2676 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone
);
2679 * Copy attributes of the original request to the clone request.
2680 * The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not copied.
2682 static void __blk_rq_prep_clone(struct request
*dst
, struct request
*src
)
2684 dst
->cpu
= src
->cpu
;
2685 dst
->cmd_flags
= (src
->cmd_flags
& REQ_CLONE_MASK
) | REQ_NOMERGE
;
2686 dst
->cmd_type
= src
->cmd_type
;
2687 dst
->__sector
= blk_rq_pos(src
);
2688 dst
->__data_len
= blk_rq_bytes(src
);
2689 dst
->nr_phys_segments
= src
->nr_phys_segments
;
2690 dst
->ioprio
= src
->ioprio
;
2691 dst
->extra_len
= src
->extra_len
;
2695 * blk_rq_prep_clone - Helper function to setup clone request
2696 * @rq: the request to be setup
2697 * @rq_src: original request to be cloned
2698 * @bs: bio_set that bios for clone are allocated from
2699 * @gfp_mask: memory allocation mask for bio
2700 * @bio_ctr: setup function to be called for each clone bio.
2701 * Returns %0 for success, non %0 for failure.
2702 * @data: private data to be passed to @bio_ctr
2705 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
2706 * The actual data parts of @rq_src (e.g. ->cmd, ->buffer, ->sense)
2707 * are not copied, and copying such parts is the caller's responsibility.
2708 * Also, pages which the original bios are pointing to are not copied
2709 * and the cloned bios just point same pages.
2710 * So cloned bios must be completed before original bios, which means
2711 * the caller must complete @rq before @rq_src.
2713 int blk_rq_prep_clone(struct request
*rq
, struct request
*rq_src
,
2714 struct bio_set
*bs
, gfp_t gfp_mask
,
2715 int (*bio_ctr
)(struct bio
*, struct bio
*, void *),
2718 struct bio
*bio
, *bio_src
;
2723 blk_rq_init(NULL
, rq
);
2725 __rq_for_each_bio(bio_src
, rq_src
) {
2726 bio
= bio_alloc_bioset(gfp_mask
, bio_src
->bi_max_vecs
, bs
);
2730 __bio_clone(bio
, bio_src
);
2732 if (bio_integrity(bio_src
) &&
2733 bio_integrity_clone(bio
, bio_src
, gfp_mask
, bs
))
2736 if (bio_ctr
&& bio_ctr(bio
, bio_src
, data
))
2740 rq
->biotail
->bi_next
= bio
;
2743 rq
->bio
= rq
->biotail
= bio
;
2746 __blk_rq_prep_clone(rq
, rq_src
);
2753 blk_rq_unprep_clone(rq
);
2757 EXPORT_SYMBOL_GPL(blk_rq_prep_clone
);
2759 int kblockd_schedule_work(struct request_queue
*q
, struct work_struct
*work
)
2761 return queue_work(kblockd_workqueue
, work
);
2763 EXPORT_SYMBOL(kblockd_schedule_work
);
2765 int kblockd_schedule_delayed_work(struct request_queue
*q
,
2766 struct delayed_work
*dwork
, unsigned long delay
)
2768 return queue_delayed_work(kblockd_workqueue
, dwork
, delay
);
2770 EXPORT_SYMBOL(kblockd_schedule_delayed_work
);
2772 #define PLUG_MAGIC 0x91827364
2775 * blk_start_plug - initialize blk_plug and track it inside the task_struct
2776 * @plug: The &struct blk_plug that needs to be initialized
2779 * Tracking blk_plug inside the task_struct will help with auto-flushing the
2780 * pending I/O should the task end up blocking between blk_start_plug() and
2781 * blk_finish_plug(). This is important from a performance perspective, but
2782 * also ensures that we don't deadlock. For instance, if the task is blocking
2783 * for a memory allocation, memory reclaim could end up wanting to free a
2784 * page belonging to that request that is currently residing in our private
2785 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
2786 * this kind of deadlock.
2788 void blk_start_plug(struct blk_plug
*plug
)
2790 struct task_struct
*tsk
= current
;
2792 plug
->magic
= PLUG_MAGIC
;
2793 INIT_LIST_HEAD(&plug
->list
);
2794 INIT_LIST_HEAD(&plug
->cb_list
);
2795 plug
->should_sort
= 0;
2798 * If this is a nested plug, don't actually assign it. It will be
2799 * flushed on its own.
2803 * Store ordering should not be needed here, since a potential
2804 * preempt will imply a full memory barrier
2809 EXPORT_SYMBOL(blk_start_plug
);
2811 static int plug_rq_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
2813 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
2814 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
2816 return !(rqa
->q
<= rqb
->q
);
2820 * If 'from_schedule' is true, then postpone the dispatch of requests
2821 * until a safe kblockd context. We due this to avoid accidental big
2822 * additional stack usage in driver dispatch, in places where the originally
2823 * plugger did not intend it.
2825 static void queue_unplugged(struct request_queue
*q
, unsigned int depth
,
2827 __releases(q
->queue_lock
)
2829 trace_block_unplug(q
, depth
, !from_schedule
);
2832 * Don't mess with dead queue.
2834 if (unlikely(blk_queue_dead(q
))) {
2835 spin_unlock(q
->queue_lock
);
2840 * If we are punting this to kblockd, then we can safely drop
2841 * the queue_lock before waking kblockd (which needs to take
2844 if (from_schedule
) {
2845 spin_unlock(q
->queue_lock
);
2846 blk_run_queue_async(q
);
2849 spin_unlock(q
->queue_lock
);
2854 static void flush_plug_callbacks(struct blk_plug
*plug
)
2856 LIST_HEAD(callbacks
);
2858 if (list_empty(&plug
->cb_list
))
2861 list_splice_init(&plug
->cb_list
, &callbacks
);
2863 while (!list_empty(&callbacks
)) {
2864 struct blk_plug_cb
*cb
= list_first_entry(&callbacks
,
2867 list_del(&cb
->list
);
2872 void blk_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
2874 struct request_queue
*q
;
2875 unsigned long flags
;
2880 BUG_ON(plug
->magic
!= PLUG_MAGIC
);
2882 flush_plug_callbacks(plug
);
2883 if (list_empty(&plug
->list
))
2886 list_splice_init(&plug
->list
, &list
);
2888 if (plug
->should_sort
) {
2889 list_sort(NULL
, &list
, plug_rq_cmp
);
2890 plug
->should_sort
= 0;
2897 * Save and disable interrupts here, to avoid doing it for every
2898 * queue lock we have to take.
2900 local_irq_save(flags
);
2901 while (!list_empty(&list
)) {
2902 rq
= list_entry_rq(list
.next
);
2903 list_del_init(&rq
->queuelist
);
2907 * This drops the queue lock
2910 queue_unplugged(q
, depth
, from_schedule
);
2913 spin_lock(q
->queue_lock
);
2917 * Short-circuit if @q is dead
2919 if (unlikely(blk_queue_dead(q
))) {
2920 __blk_end_request_all(rq
, -ENODEV
);
2925 * rq is already accounted, so use raw insert
2927 if (rq
->cmd_flags
& (REQ_FLUSH
| REQ_FUA
))
2928 __elv_add_request(q
, rq
, ELEVATOR_INSERT_FLUSH
);
2930 __elv_add_request(q
, rq
, ELEVATOR_INSERT_SORT_MERGE
);
2936 * This drops the queue lock
2939 queue_unplugged(q
, depth
, from_schedule
);
2941 local_irq_restore(flags
);
2944 void blk_finish_plug(struct blk_plug
*plug
)
2946 blk_flush_plug_list(plug
, false);
2948 if (plug
== current
->plug
)
2949 current
->plug
= NULL
;
2951 EXPORT_SYMBOL(blk_finish_plug
);
2953 int __init
blk_dev_init(void)
2955 BUILD_BUG_ON(__REQ_NR_BITS
> 8 *
2956 sizeof(((struct request
*)0)->cmd_flags
));
2958 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
2959 kblockd_workqueue
= alloc_workqueue("kblockd",
2960 WQ_MEM_RECLAIM
| WQ_HIGHPRI
, 0);
2961 if (!kblockd_workqueue
)
2962 panic("Failed to create kblockd\n");
2964 request_cachep
= kmem_cache_create("blkdev_requests",
2965 sizeof(struct request
), 0, SLAB_PANIC
, NULL
);
2967 blk_requestq_cachep
= kmem_cache_create("blkdev_queue",
2968 sizeof(struct request_queue
), 0, SLAB_PANIC
, NULL
);