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>
31 #define CREATE_TRACE_POINTS
32 #include <trace/events/block.h>
36 EXPORT_TRACEPOINT_SYMBOL_GPL(block_remap
);
37 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete
);
39 static int __make_request(struct request_queue
*q
, struct bio
*bio
);
42 * For the allocated request tables
44 static struct kmem_cache
*request_cachep
;
47 * For queue allocation
49 struct kmem_cache
*blk_requestq_cachep
;
52 * Controlling structure to kblockd
54 static struct workqueue_struct
*kblockd_workqueue
;
56 static void drive_stat_acct(struct request
*rq
, int new_io
)
58 struct hd_struct
*part
;
59 int rw
= rq_data_dir(rq
);
62 if (!blk_do_io_stat(rq
))
65 cpu
= part_stat_lock();
66 part
= disk_map_sector_rcu(rq
->rq_disk
, blk_rq_pos(rq
));
69 part_stat_inc(cpu
, part
, merges
[rw
]);
71 part_round_stats(cpu
, part
);
72 part_inc_in_flight(part
);
78 void blk_queue_congestion_threshold(struct request_queue
*q
)
82 nr
= q
->nr_requests
- (q
->nr_requests
/ 8) + 1;
83 if (nr
> q
->nr_requests
)
85 q
->nr_congestion_on
= nr
;
87 nr
= q
->nr_requests
- (q
->nr_requests
/ 8) - (q
->nr_requests
/ 16) - 1;
90 q
->nr_congestion_off
= nr
;
94 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
97 * Locates the passed device's request queue and returns the address of its
100 * Will return NULL if the request queue cannot be located.
102 struct backing_dev_info
*blk_get_backing_dev_info(struct block_device
*bdev
)
104 struct backing_dev_info
*ret
= NULL
;
105 struct request_queue
*q
= bdev_get_queue(bdev
);
108 ret
= &q
->backing_dev_info
;
111 EXPORT_SYMBOL(blk_get_backing_dev_info
);
113 void blk_rq_init(struct request_queue
*q
, struct request
*rq
)
115 memset(rq
, 0, sizeof(*rq
));
117 INIT_LIST_HEAD(&rq
->queuelist
);
118 INIT_LIST_HEAD(&rq
->timeout_list
);
121 rq
->__sector
= (sector_t
) -1;
122 INIT_HLIST_NODE(&rq
->hash
);
123 RB_CLEAR_NODE(&rq
->rb_node
);
125 rq
->cmd_len
= BLK_MAX_CDB
;
128 rq
->start_time
= jiffies
;
130 EXPORT_SYMBOL(blk_rq_init
);
132 static void req_bio_endio(struct request
*rq
, struct bio
*bio
,
133 unsigned int nbytes
, int error
)
135 struct request_queue
*q
= rq
->q
;
137 if (&q
->bar_rq
!= rq
) {
139 clear_bit(BIO_UPTODATE
, &bio
->bi_flags
);
140 else if (!test_bit(BIO_UPTODATE
, &bio
->bi_flags
))
143 if (unlikely(nbytes
> bio
->bi_size
)) {
144 printk(KERN_ERR
"%s: want %u bytes done, %u left\n",
145 __func__
, nbytes
, bio
->bi_size
);
146 nbytes
= bio
->bi_size
;
149 if (unlikely(rq
->cmd_flags
& REQ_QUIET
))
150 set_bit(BIO_QUIET
, &bio
->bi_flags
);
152 bio
->bi_size
-= nbytes
;
153 bio
->bi_sector
+= (nbytes
>> 9);
155 if (bio_integrity(bio
))
156 bio_integrity_advance(bio
, nbytes
);
158 if (bio
->bi_size
== 0)
159 bio_endio(bio
, error
);
163 * Okay, this is the barrier request in progress, just
166 if (error
&& !q
->orderr
)
171 void blk_dump_rq_flags(struct request
*rq
, char *msg
)
175 printk(KERN_INFO
"%s: dev %s: type=%x, flags=%x\n", msg
,
176 rq
->rq_disk
? rq
->rq_disk
->disk_name
: "?", rq
->cmd_type
,
179 printk(KERN_INFO
" sector %llu, nr/cnr %u/%u\n",
180 (unsigned long long)blk_rq_pos(rq
),
181 blk_rq_sectors(rq
), blk_rq_cur_sectors(rq
));
182 printk(KERN_INFO
" bio %p, biotail %p, buffer %p, len %u\n",
183 rq
->bio
, rq
->biotail
, rq
->buffer
, blk_rq_bytes(rq
));
185 if (blk_pc_request(rq
)) {
186 printk(KERN_INFO
" cdb: ");
187 for (bit
= 0; bit
< BLK_MAX_CDB
; bit
++)
188 printk("%02x ", rq
->cmd
[bit
]);
192 EXPORT_SYMBOL(blk_dump_rq_flags
);
195 * "plug" the device if there are no outstanding requests: this will
196 * force the transfer to start only after we have put all the requests
199 * This is called with interrupts off and no requests on the queue and
200 * with the queue lock held.
202 void blk_plug_device(struct request_queue
*q
)
204 WARN_ON(!irqs_disabled());
207 * don't plug a stopped queue, it must be paired with blk_start_queue()
208 * which will restart the queueing
210 if (blk_queue_stopped(q
))
213 if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED
, q
)) {
214 mod_timer(&q
->unplug_timer
, jiffies
+ q
->unplug_delay
);
218 EXPORT_SYMBOL(blk_plug_device
);
221 * blk_plug_device_unlocked - plug a device without queue lock held
222 * @q: The &struct request_queue to plug
225 * Like @blk_plug_device(), but grabs the queue lock and disables
228 void blk_plug_device_unlocked(struct request_queue
*q
)
232 spin_lock_irqsave(q
->queue_lock
, flags
);
234 spin_unlock_irqrestore(q
->queue_lock
, flags
);
236 EXPORT_SYMBOL(blk_plug_device_unlocked
);
239 * remove the queue from the plugged list, if present. called with
240 * queue lock held and interrupts disabled.
242 int blk_remove_plug(struct request_queue
*q
)
244 WARN_ON(!irqs_disabled());
246 if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED
, q
))
249 del_timer(&q
->unplug_timer
);
252 EXPORT_SYMBOL(blk_remove_plug
);
255 * remove the plug and let it rip..
257 void __generic_unplug_device(struct request_queue
*q
)
259 if (unlikely(blk_queue_stopped(q
)))
261 if (!blk_remove_plug(q
) && !blk_queue_nonrot(q
))
268 * generic_unplug_device - fire a request queue
269 * @q: The &struct request_queue in question
272 * Linux uses plugging to build bigger requests queues before letting
273 * the device have at them. If a queue is plugged, the I/O scheduler
274 * is still adding and merging requests on the queue. Once the queue
275 * gets unplugged, the request_fn defined for the queue is invoked and
278 void generic_unplug_device(struct request_queue
*q
)
280 if (blk_queue_plugged(q
)) {
281 spin_lock_irq(q
->queue_lock
);
282 __generic_unplug_device(q
);
283 spin_unlock_irq(q
->queue_lock
);
286 EXPORT_SYMBOL(generic_unplug_device
);
288 static void blk_backing_dev_unplug(struct backing_dev_info
*bdi
,
291 struct request_queue
*q
= bdi
->unplug_io_data
;
296 void blk_unplug_work(struct work_struct
*work
)
298 struct request_queue
*q
=
299 container_of(work
, struct request_queue
, unplug_work
);
301 trace_block_unplug_io(q
);
305 void blk_unplug_timeout(unsigned long data
)
307 struct request_queue
*q
= (struct request_queue
*)data
;
309 trace_block_unplug_timer(q
);
310 kblockd_schedule_work(q
, &q
->unplug_work
);
313 void blk_unplug(struct request_queue
*q
)
316 * devices don't necessarily have an ->unplug_fn defined
319 trace_block_unplug_io(q
);
323 EXPORT_SYMBOL(blk_unplug
);
326 * blk_start_queue - restart a previously stopped queue
327 * @q: The &struct request_queue in question
330 * blk_start_queue() will clear the stop flag on the queue, and call
331 * the request_fn for the queue if it was in a stopped state when
332 * entered. Also see blk_stop_queue(). Queue lock must be held.
334 void blk_start_queue(struct request_queue
*q
)
336 WARN_ON(!irqs_disabled());
338 queue_flag_clear(QUEUE_FLAG_STOPPED
, q
);
341 EXPORT_SYMBOL(blk_start_queue
);
344 * blk_stop_queue - stop a queue
345 * @q: The &struct request_queue in question
348 * The Linux block layer assumes that a block driver will consume all
349 * entries on the request queue when the request_fn strategy is called.
350 * Often this will not happen, because of hardware limitations (queue
351 * depth settings). If a device driver gets a 'queue full' response,
352 * or if it simply chooses not to queue more I/O at one point, it can
353 * call this function to prevent the request_fn from being called until
354 * the driver has signalled it's ready to go again. This happens by calling
355 * blk_start_queue() to restart queue operations. Queue lock must be held.
357 void blk_stop_queue(struct request_queue
*q
)
360 queue_flag_set(QUEUE_FLAG_STOPPED
, q
);
362 EXPORT_SYMBOL(blk_stop_queue
);
365 * blk_sync_queue - cancel any pending callbacks on a queue
369 * The block layer may perform asynchronous callback activity
370 * on a queue, such as calling the unplug function after a timeout.
371 * A block device may call blk_sync_queue to ensure that any
372 * such activity is cancelled, thus allowing it to release resources
373 * that the callbacks might use. The caller must already have made sure
374 * that its ->make_request_fn will not re-add plugging prior to calling
378 void blk_sync_queue(struct request_queue
*q
)
380 del_timer_sync(&q
->unplug_timer
);
381 del_timer_sync(&q
->timeout
);
382 cancel_work_sync(&q
->unplug_work
);
384 EXPORT_SYMBOL(blk_sync_queue
);
387 * __blk_run_queue - run a single device queue
388 * @q: The queue to run
391 * See @blk_run_queue. This variant must be called with the queue lock
392 * held and interrupts disabled.
395 void __blk_run_queue(struct request_queue
*q
)
399 if (unlikely(blk_queue_stopped(q
)))
402 if (elv_queue_empty(q
))
406 * Only recurse once to avoid overrunning the stack, let the unplug
407 * handling reinvoke the handler shortly if we already got there.
409 if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER
, q
)) {
411 queue_flag_clear(QUEUE_FLAG_REENTER
, q
);
413 queue_flag_set(QUEUE_FLAG_PLUGGED
, q
);
414 kblockd_schedule_work(q
, &q
->unplug_work
);
417 EXPORT_SYMBOL(__blk_run_queue
);
420 * blk_run_queue - run a single device queue
421 * @q: The queue to run
424 * Invoke request handling on this queue, if it has pending work to do.
425 * May be used to restart queueing when a request has completed.
427 void blk_run_queue(struct request_queue
*q
)
431 spin_lock_irqsave(q
->queue_lock
, flags
);
433 spin_unlock_irqrestore(q
->queue_lock
, flags
);
435 EXPORT_SYMBOL(blk_run_queue
);
437 void blk_put_queue(struct request_queue
*q
)
439 kobject_put(&q
->kobj
);
442 void blk_cleanup_queue(struct request_queue
*q
)
445 * We know we have process context here, so we can be a little
446 * cautious and ensure that pending block actions on this device
447 * are done before moving on. Going into this function, we should
448 * not have processes doing IO to this device.
452 mutex_lock(&q
->sysfs_lock
);
453 queue_flag_set_unlocked(QUEUE_FLAG_DEAD
, q
);
454 mutex_unlock(&q
->sysfs_lock
);
457 elevator_exit(q
->elevator
);
461 EXPORT_SYMBOL(blk_cleanup_queue
);
463 static int blk_init_free_list(struct request_queue
*q
)
465 struct request_list
*rl
= &q
->rq
;
467 rl
->count
[BLK_RW_SYNC
] = rl
->count
[BLK_RW_ASYNC
] = 0;
468 rl
->starved
[BLK_RW_SYNC
] = rl
->starved
[BLK_RW_ASYNC
] = 0;
470 init_waitqueue_head(&rl
->wait
[BLK_RW_SYNC
]);
471 init_waitqueue_head(&rl
->wait
[BLK_RW_ASYNC
]);
473 rl
->rq_pool
= mempool_create_node(BLKDEV_MIN_RQ
, mempool_alloc_slab
,
474 mempool_free_slab
, request_cachep
, q
->node
);
482 struct request_queue
*blk_alloc_queue(gfp_t gfp_mask
)
484 return blk_alloc_queue_node(gfp_mask
, -1);
486 EXPORT_SYMBOL(blk_alloc_queue
);
488 struct request_queue
*blk_alloc_queue_node(gfp_t gfp_mask
, int node_id
)
490 struct request_queue
*q
;
493 q
= kmem_cache_alloc_node(blk_requestq_cachep
,
494 gfp_mask
| __GFP_ZERO
, node_id
);
498 q
->backing_dev_info
.unplug_io_fn
= blk_backing_dev_unplug
;
499 q
->backing_dev_info
.unplug_io_data
= q
;
500 q
->backing_dev_info
.ra_pages
=
501 (VM_MAX_READAHEAD
* 1024) / PAGE_CACHE_SIZE
;
502 q
->backing_dev_info
.state
= 0;
503 q
->backing_dev_info
.capabilities
= BDI_CAP_MAP_COPY
;
505 err
= bdi_init(&q
->backing_dev_info
);
507 kmem_cache_free(blk_requestq_cachep
, q
);
511 init_timer(&q
->unplug_timer
);
512 setup_timer(&q
->timeout
, blk_rq_timed_out_timer
, (unsigned long) q
);
513 INIT_LIST_HEAD(&q
->timeout_list
);
514 INIT_WORK(&q
->unplug_work
, blk_unplug_work
);
516 kobject_init(&q
->kobj
, &blk_queue_ktype
);
518 mutex_init(&q
->sysfs_lock
);
519 spin_lock_init(&q
->__queue_lock
);
523 EXPORT_SYMBOL(blk_alloc_queue_node
);
526 * blk_init_queue - prepare a request queue for use with a block device
527 * @rfn: The function to be called to process requests that have been
528 * placed on the queue.
529 * @lock: Request queue spin lock
532 * If a block device wishes to use the standard request handling procedures,
533 * which sorts requests and coalesces adjacent requests, then it must
534 * call blk_init_queue(). The function @rfn will be called when there
535 * are requests on the queue that need to be processed. If the device
536 * supports plugging, then @rfn may not be called immediately when requests
537 * are available on the queue, but may be called at some time later instead.
538 * Plugged queues are generally unplugged when a buffer belonging to one
539 * of the requests on the queue is needed, or due to memory pressure.
541 * @rfn is not required, or even expected, to remove all requests off the
542 * queue, but only as many as it can handle at a time. If it does leave
543 * requests on the queue, it is responsible for arranging that the requests
544 * get dealt with eventually.
546 * The queue spin lock must be held while manipulating the requests on the
547 * request queue; this lock will be taken also from interrupt context, so irq
548 * disabling is needed for it.
550 * Function returns a pointer to the initialized request queue, or %NULL if
554 * blk_init_queue() must be paired with a blk_cleanup_queue() call
555 * when the block device is deactivated (such as at module unload).
558 struct request_queue
*blk_init_queue(request_fn_proc
*rfn
, spinlock_t
*lock
)
560 return blk_init_queue_node(rfn
, lock
, -1);
562 EXPORT_SYMBOL(blk_init_queue
);
564 struct request_queue
*
565 blk_init_queue_node(request_fn_proc
*rfn
, spinlock_t
*lock
, int node_id
)
567 struct request_queue
*q
= blk_alloc_queue_node(GFP_KERNEL
, node_id
);
573 if (blk_init_free_list(q
)) {
574 kmem_cache_free(blk_requestq_cachep
, q
);
579 q
->prep_rq_fn
= NULL
;
580 q
->unplug_fn
= generic_unplug_device
;
581 q
->queue_flags
= QUEUE_FLAG_DEFAULT
;
582 q
->queue_lock
= lock
;
585 * This also sets hw/phys segments, boundary and size
587 blk_queue_make_request(q
, __make_request
);
589 q
->sg_reserved_size
= INT_MAX
;
594 if (!elevator_init(q
, NULL
)) {
595 blk_queue_congestion_threshold(q
);
602 EXPORT_SYMBOL(blk_init_queue_node
);
604 int blk_get_queue(struct request_queue
*q
)
606 if (likely(!test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
))) {
607 kobject_get(&q
->kobj
);
614 static inline void blk_free_request(struct request_queue
*q
, struct request
*rq
)
616 if (rq
->cmd_flags
& REQ_ELVPRIV
)
617 elv_put_request(q
, rq
);
618 mempool_free(rq
, q
->rq
.rq_pool
);
621 static struct request
*
622 blk_alloc_request(struct request_queue
*q
, int flags
, int priv
, gfp_t gfp_mask
)
624 struct request
*rq
= mempool_alloc(q
->rq
.rq_pool
, gfp_mask
);
631 rq
->cmd_flags
= flags
| REQ_ALLOCED
;
634 if (unlikely(elv_set_request(q
, rq
, gfp_mask
))) {
635 mempool_free(rq
, q
->rq
.rq_pool
);
638 rq
->cmd_flags
|= REQ_ELVPRIV
;
645 * ioc_batching returns true if the ioc is a valid batching request and
646 * should be given priority access to a request.
648 static inline int ioc_batching(struct request_queue
*q
, struct io_context
*ioc
)
654 * Make sure the process is able to allocate at least 1 request
655 * even if the batch times out, otherwise we could theoretically
658 return ioc
->nr_batch_requests
== q
->nr_batching
||
659 (ioc
->nr_batch_requests
> 0
660 && time_before(jiffies
, ioc
->last_waited
+ BLK_BATCH_TIME
));
664 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
665 * will cause the process to be a "batcher" on all queues in the system. This
666 * is the behaviour we want though - once it gets a wakeup it should be given
669 static void ioc_set_batching(struct request_queue
*q
, struct io_context
*ioc
)
671 if (!ioc
|| ioc_batching(q
, ioc
))
674 ioc
->nr_batch_requests
= q
->nr_batching
;
675 ioc
->last_waited
= jiffies
;
678 static void __freed_request(struct request_queue
*q
, int sync
)
680 struct request_list
*rl
= &q
->rq
;
682 if (rl
->count
[sync
] < queue_congestion_off_threshold(q
))
683 blk_clear_queue_congested(q
, sync
);
685 if (rl
->count
[sync
] + 1 <= q
->nr_requests
) {
686 if (waitqueue_active(&rl
->wait
[sync
]))
687 wake_up(&rl
->wait
[sync
]);
689 blk_clear_queue_full(q
, sync
);
694 * A request has just been released. Account for it, update the full and
695 * congestion status, wake up any waiters. Called under q->queue_lock.
697 static void freed_request(struct request_queue
*q
, int sync
, int priv
)
699 struct request_list
*rl
= &q
->rq
;
705 __freed_request(q
, sync
);
707 if (unlikely(rl
->starved
[sync
^ 1]))
708 __freed_request(q
, sync
^ 1);
712 * Get a free request, queue_lock must be held.
713 * Returns NULL on failure, with queue_lock held.
714 * Returns !NULL on success, with queue_lock *not held*.
716 static struct request
*get_request(struct request_queue
*q
, int rw_flags
,
717 struct bio
*bio
, gfp_t gfp_mask
)
719 struct request
*rq
= NULL
;
720 struct request_list
*rl
= &q
->rq
;
721 struct io_context
*ioc
= NULL
;
722 const bool is_sync
= rw_is_sync(rw_flags
) != 0;
725 may_queue
= elv_may_queue(q
, rw_flags
);
726 if (may_queue
== ELV_MQUEUE_NO
)
729 if (rl
->count
[is_sync
]+1 >= queue_congestion_on_threshold(q
)) {
730 if (rl
->count
[is_sync
]+1 >= q
->nr_requests
) {
731 ioc
= current_io_context(GFP_ATOMIC
, q
->node
);
733 * The queue will fill after this allocation, so set
734 * it as full, and mark this process as "batching".
735 * This process will be allowed to complete a batch of
736 * requests, others will be blocked.
738 if (!blk_queue_full(q
, is_sync
)) {
739 ioc_set_batching(q
, ioc
);
740 blk_set_queue_full(q
, is_sync
);
742 if (may_queue
!= ELV_MQUEUE_MUST
743 && !ioc_batching(q
, ioc
)) {
745 * The queue is full and the allocating
746 * process is not a "batcher", and not
747 * exempted by the IO scheduler
753 blk_set_queue_congested(q
, is_sync
);
757 * Only allow batching queuers to allocate up to 50% over the defined
758 * limit of requests, otherwise we could have thousands of requests
759 * allocated with any setting of ->nr_requests
761 if (rl
->count
[is_sync
] >= (3 * q
->nr_requests
/ 2))
764 rl
->count
[is_sync
]++;
765 rl
->starved
[is_sync
] = 0;
767 priv
= !test_bit(QUEUE_FLAG_ELVSWITCH
, &q
->queue_flags
);
771 if (blk_queue_io_stat(q
))
772 rw_flags
|= REQ_IO_STAT
;
773 spin_unlock_irq(q
->queue_lock
);
775 rq
= blk_alloc_request(q
, rw_flags
, priv
, gfp_mask
);
778 * Allocation failed presumably due to memory. Undo anything
779 * we might have messed up.
781 * Allocating task should really be put onto the front of the
782 * wait queue, but this is pretty rare.
784 spin_lock_irq(q
->queue_lock
);
785 freed_request(q
, is_sync
, priv
);
788 * in the very unlikely event that allocation failed and no
789 * requests for this direction was pending, mark us starved
790 * so that freeing of a request in the other direction will
791 * notice us. another possible fix would be to split the
792 * rq mempool into READ and WRITE
795 if (unlikely(rl
->count
[is_sync
] == 0))
796 rl
->starved
[is_sync
] = 1;
802 * ioc may be NULL here, and ioc_batching will be false. That's
803 * OK, if the queue is under the request limit then requests need
804 * not count toward the nr_batch_requests limit. There will always
805 * be some limit enforced by BLK_BATCH_TIME.
807 if (ioc_batching(q
, ioc
))
808 ioc
->nr_batch_requests
--;
810 trace_block_getrq(q
, bio
, rw_flags
& 1);
816 * No available requests for this queue, unplug the device and wait for some
817 * requests to become available.
819 * Called with q->queue_lock held, and returns with it unlocked.
821 static struct request
*get_request_wait(struct request_queue
*q
, int rw_flags
,
824 const bool is_sync
= rw_is_sync(rw_flags
) != 0;
827 rq
= get_request(q
, rw_flags
, bio
, GFP_NOIO
);
830 struct io_context
*ioc
;
831 struct request_list
*rl
= &q
->rq
;
833 prepare_to_wait_exclusive(&rl
->wait
[is_sync
], &wait
,
834 TASK_UNINTERRUPTIBLE
);
836 trace_block_sleeprq(q
, bio
, rw_flags
& 1);
838 __generic_unplug_device(q
);
839 spin_unlock_irq(q
->queue_lock
);
843 * After sleeping, we become a "batching" process and
844 * will be able to allocate at least one request, and
845 * up to a big batch of them for a small period time.
846 * See ioc_batching, ioc_set_batching
848 ioc
= current_io_context(GFP_NOIO
, q
->node
);
849 ioc_set_batching(q
, ioc
);
851 spin_lock_irq(q
->queue_lock
);
852 finish_wait(&rl
->wait
[is_sync
], &wait
);
854 rq
= get_request(q
, rw_flags
, bio
, GFP_NOIO
);
860 struct request
*blk_get_request(struct request_queue
*q
, int rw
, gfp_t gfp_mask
)
864 BUG_ON(rw
!= READ
&& rw
!= WRITE
);
866 spin_lock_irq(q
->queue_lock
);
867 if (gfp_mask
& __GFP_WAIT
) {
868 rq
= get_request_wait(q
, rw
, NULL
);
870 rq
= get_request(q
, rw
, NULL
, gfp_mask
);
872 spin_unlock_irq(q
->queue_lock
);
874 /* q->queue_lock is unlocked at this point */
878 EXPORT_SYMBOL(blk_get_request
);
881 * blk_make_request - given a bio, allocate a corresponding struct request.
882 * @q: target request queue
883 * @bio: The bio describing the memory mappings that will be submitted for IO.
884 * It may be a chained-bio properly constructed by block/bio layer.
885 * @gfp_mask: gfp flags to be used for memory allocation
887 * blk_make_request is the parallel of generic_make_request for BLOCK_PC
888 * type commands. Where the struct request needs to be farther initialized by
889 * the caller. It is passed a &struct bio, which describes the memory info of
892 * The caller of blk_make_request must make sure that bi_io_vec
893 * are set to describe the memory buffers. That bio_data_dir() will return
894 * the needed direction of the request. (And all bio's in the passed bio-chain
895 * are properly set accordingly)
897 * If called under none-sleepable conditions, mapped bio buffers must not
898 * need bouncing, by calling the appropriate masked or flagged allocator,
899 * suitable for the target device. Otherwise the call to blk_queue_bounce will
902 * WARNING: When allocating/cloning a bio-chain, careful consideration should be
903 * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for
904 * anything but the first bio in the chain. Otherwise you risk waiting for IO
905 * completion of a bio that hasn't been submitted yet, thus resulting in a
906 * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead
907 * of bio_alloc(), as that avoids the mempool deadlock.
908 * If possible a big IO should be split into smaller parts when allocation
909 * fails. Partial allocation should not be an error, or you risk a live-lock.
911 struct request
*blk_make_request(struct request_queue
*q
, struct bio
*bio
,
914 struct request
*rq
= blk_get_request(q
, bio_data_dir(bio
), gfp_mask
);
917 return ERR_PTR(-ENOMEM
);
920 struct bio
*bounce_bio
= bio
;
923 blk_queue_bounce(q
, &bounce_bio
);
924 ret
= blk_rq_append_bio(q
, rq
, bounce_bio
);
933 EXPORT_SYMBOL(blk_make_request
);
936 * blk_requeue_request - put a request back on queue
937 * @q: request queue where request should be inserted
938 * @rq: request to be inserted
941 * Drivers often keep queueing requests until the hardware cannot accept
942 * more, when that condition happens we need to put the request back
943 * on the queue. Must be called with queue lock held.
945 void blk_requeue_request(struct request_queue
*q
, struct request
*rq
)
947 blk_delete_timer(rq
);
948 blk_clear_rq_complete(rq
);
949 trace_block_rq_requeue(q
, rq
);
951 if (blk_rq_tagged(rq
))
952 blk_queue_end_tag(q
, rq
);
954 BUG_ON(blk_queued_rq(rq
));
956 elv_requeue_request(q
, rq
);
958 EXPORT_SYMBOL(blk_requeue_request
);
961 * blk_insert_request - insert a special request into a request queue
962 * @q: request queue where request should be inserted
963 * @rq: request to be inserted
964 * @at_head: insert request at head or tail of queue
965 * @data: private data
968 * Many block devices need to execute commands asynchronously, so they don't
969 * block the whole kernel from preemption during request execution. This is
970 * accomplished normally by inserting aritficial requests tagged as
971 * REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them
972 * be scheduled for actual execution by the request queue.
974 * We have the option of inserting the head or the tail of the queue.
975 * Typically we use the tail for new ioctls and so forth. We use the head
976 * of the queue for things like a QUEUE_FULL message from a device, or a
977 * host that is unable to accept a particular command.
979 void blk_insert_request(struct request_queue
*q
, struct request
*rq
,
980 int at_head
, void *data
)
982 int where
= at_head
? ELEVATOR_INSERT_FRONT
: ELEVATOR_INSERT_BACK
;
986 * tell I/O scheduler that this isn't a regular read/write (ie it
987 * must not attempt merges on this) and that it acts as a soft
990 rq
->cmd_type
= REQ_TYPE_SPECIAL
;
994 spin_lock_irqsave(q
->queue_lock
, flags
);
997 * If command is tagged, release the tag
999 if (blk_rq_tagged(rq
))
1000 blk_queue_end_tag(q
, rq
);
1002 drive_stat_acct(rq
, 1);
1003 __elv_add_request(q
, rq
, where
, 0);
1005 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1007 EXPORT_SYMBOL(blk_insert_request
);
1010 * add-request adds a request to the linked list.
1011 * queue lock is held and interrupts disabled, as we muck with the
1012 * request queue list.
1014 static inline void add_request(struct request_queue
*q
, struct request
*req
)
1016 drive_stat_acct(req
, 1);
1019 * elevator indicated where it wants this request to be
1020 * inserted at elevator_merge time
1022 __elv_add_request(q
, req
, ELEVATOR_INSERT_SORT
, 0);
1025 static void part_round_stats_single(int cpu
, struct hd_struct
*part
,
1028 if (now
== part
->stamp
)
1031 if (part
->in_flight
) {
1032 __part_stat_add(cpu
, part
, time_in_queue
,
1033 part
->in_flight
* (now
- part
->stamp
));
1034 __part_stat_add(cpu
, part
, io_ticks
, (now
- part
->stamp
));
1040 * part_round_stats() - Round off the performance stats on a struct disk_stats.
1041 * @cpu: cpu number for stats access
1042 * @part: target partition
1044 * The average IO queue length and utilisation statistics are maintained
1045 * by observing the current state of the queue length and the amount of
1046 * time it has been in this state for.
1048 * Normally, that accounting is done on IO completion, but that can result
1049 * in more than a second's worth of IO being accounted for within any one
1050 * second, leading to >100% utilisation. To deal with that, we call this
1051 * function to do a round-off before returning the results when reading
1052 * /proc/diskstats. This accounts immediately for all queue usage up to
1053 * the current jiffies and restarts the counters again.
1055 void part_round_stats(int cpu
, struct hd_struct
*part
)
1057 unsigned long now
= jiffies
;
1060 part_round_stats_single(cpu
, &part_to_disk(part
)->part0
, now
);
1061 part_round_stats_single(cpu
, part
, now
);
1063 EXPORT_SYMBOL_GPL(part_round_stats
);
1066 * queue lock must be held
1068 void __blk_put_request(struct request_queue
*q
, struct request
*req
)
1072 if (unlikely(--req
->ref_count
))
1075 elv_completed_request(q
, req
);
1077 /* this is a bio leak */
1078 WARN_ON(req
->bio
!= NULL
);
1081 * Request may not have originated from ll_rw_blk. if not,
1082 * it didn't come out of our reserved rq pools
1084 if (req
->cmd_flags
& REQ_ALLOCED
) {
1085 int is_sync
= rq_is_sync(req
) != 0;
1086 int priv
= req
->cmd_flags
& REQ_ELVPRIV
;
1088 BUG_ON(!list_empty(&req
->queuelist
));
1089 BUG_ON(!hlist_unhashed(&req
->hash
));
1091 blk_free_request(q
, req
);
1092 freed_request(q
, is_sync
, priv
);
1095 EXPORT_SYMBOL_GPL(__blk_put_request
);
1097 void blk_put_request(struct request
*req
)
1099 unsigned long flags
;
1100 struct request_queue
*q
= req
->q
;
1102 spin_lock_irqsave(q
->queue_lock
, flags
);
1103 __blk_put_request(q
, req
);
1104 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1106 EXPORT_SYMBOL(blk_put_request
);
1108 void init_request_from_bio(struct request
*req
, struct bio
*bio
)
1110 req
->cpu
= bio
->bi_comp_cpu
;
1111 req
->cmd_type
= REQ_TYPE_FS
;
1114 * Inherit FAILFAST from bio (for read-ahead, and explicit
1115 * FAILFAST). FAILFAST flags are identical for req and bio.
1117 if (bio_rw_flagged(bio
, BIO_RW_AHEAD
))
1118 req
->cmd_flags
|= REQ_FAILFAST_MASK
;
1120 req
->cmd_flags
|= bio
->bi_rw
& REQ_FAILFAST_MASK
;
1122 if (unlikely(bio_rw_flagged(bio
, BIO_RW_DISCARD
))) {
1123 req
->cmd_flags
|= REQ_DISCARD
;
1124 if (bio_rw_flagged(bio
, BIO_RW_BARRIER
))
1125 req
->cmd_flags
|= REQ_SOFTBARRIER
;
1126 req
->q
->prepare_discard_fn(req
->q
, req
);
1127 } else if (unlikely(bio_rw_flagged(bio
, BIO_RW_BARRIER
)))
1128 req
->cmd_flags
|= REQ_HARDBARRIER
;
1130 if (bio_rw_flagged(bio
, BIO_RW_SYNCIO
))
1131 req
->cmd_flags
|= REQ_RW_SYNC
;
1132 if (bio_rw_flagged(bio
, BIO_RW_META
))
1133 req
->cmd_flags
|= REQ_RW_META
;
1134 if (bio_rw_flagged(bio
, BIO_RW_NOIDLE
))
1135 req
->cmd_flags
|= REQ_NOIDLE
;
1138 req
->__sector
= bio
->bi_sector
;
1139 req
->ioprio
= bio_prio(bio
);
1140 blk_rq_bio_prep(req
->q
, req
, bio
);
1144 * Only disabling plugging for non-rotational devices if it does tagging
1145 * as well, otherwise we do need the proper merging
1147 static inline bool queue_should_plug(struct request_queue
*q
)
1149 return !(blk_queue_nonrot(q
) && blk_queue_queuing(q
));
1152 static int __make_request(struct request_queue
*q
, struct bio
*bio
)
1154 struct request
*req
;
1156 unsigned int bytes
= bio
->bi_size
;
1157 const unsigned short prio
= bio_prio(bio
);
1158 const bool sync
= bio_rw_flagged(bio
, BIO_RW_SYNCIO
);
1159 const bool unplug
= bio_rw_flagged(bio
, BIO_RW_UNPLUG
);
1160 const unsigned int ff
= bio
->bi_rw
& REQ_FAILFAST_MASK
;
1163 if (bio_rw_flagged(bio
, BIO_RW_BARRIER
) && bio_has_data(bio
) &&
1164 (q
->next_ordered
== QUEUE_ORDERED_NONE
)) {
1165 bio_endio(bio
, -EOPNOTSUPP
);
1169 * low level driver can indicate that it wants pages above a
1170 * certain limit bounced to low memory (ie for highmem, or even
1171 * ISA dma in theory)
1173 blk_queue_bounce(q
, &bio
);
1175 spin_lock_irq(q
->queue_lock
);
1177 if (unlikely(bio_rw_flagged(bio
, BIO_RW_BARRIER
)) || elv_queue_empty(q
))
1180 el_ret
= elv_merge(q
, &req
, bio
);
1182 case ELEVATOR_BACK_MERGE
:
1183 BUG_ON(!rq_mergeable(req
));
1185 if (!ll_back_merge_fn(q
, req
, bio
))
1188 trace_block_bio_backmerge(q
, bio
);
1190 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
)
1191 blk_rq_set_mixed_merge(req
);
1193 req
->biotail
->bi_next
= bio
;
1195 req
->__data_len
+= bytes
;
1196 req
->ioprio
= ioprio_best(req
->ioprio
, prio
);
1197 if (!blk_rq_cpu_valid(req
))
1198 req
->cpu
= bio
->bi_comp_cpu
;
1199 drive_stat_acct(req
, 0);
1200 if (!attempt_back_merge(q
, req
))
1201 elv_merged_request(q
, req
, el_ret
);
1204 case ELEVATOR_FRONT_MERGE
:
1205 BUG_ON(!rq_mergeable(req
));
1207 if (!ll_front_merge_fn(q
, req
, bio
))
1210 trace_block_bio_frontmerge(q
, bio
);
1212 if ((req
->cmd_flags
& REQ_FAILFAST_MASK
) != ff
) {
1213 blk_rq_set_mixed_merge(req
);
1214 req
->cmd_flags
&= ~REQ_FAILFAST_MASK
;
1215 req
->cmd_flags
|= ff
;
1218 bio
->bi_next
= req
->bio
;
1222 * may not be valid. if the low level driver said
1223 * it didn't need a bounce buffer then it better
1224 * not touch req->buffer either...
1226 req
->buffer
= bio_data(bio
);
1227 req
->__sector
= bio
->bi_sector
;
1228 req
->__data_len
+= bytes
;
1229 req
->ioprio
= ioprio_best(req
->ioprio
, prio
);
1230 if (!blk_rq_cpu_valid(req
))
1231 req
->cpu
= bio
->bi_comp_cpu
;
1232 drive_stat_acct(req
, 0);
1233 if (!attempt_front_merge(q
, req
))
1234 elv_merged_request(q
, req
, el_ret
);
1237 /* ELV_NO_MERGE: elevator says don't/can't merge. */
1244 * This sync check and mask will be re-done in init_request_from_bio(),
1245 * but we need to set it earlier to expose the sync flag to the
1246 * rq allocator and io schedulers.
1248 rw_flags
= bio_data_dir(bio
);
1250 rw_flags
|= REQ_RW_SYNC
;
1253 * Grab a free request. This is might sleep but can not fail.
1254 * Returns with the queue unlocked.
1256 req
= get_request_wait(q
, rw_flags
, bio
);
1259 * After dropping the lock and possibly sleeping here, our request
1260 * may now be mergeable after it had proven unmergeable (above).
1261 * We don't worry about that case for efficiency. It won't happen
1262 * often, and the elevators are able to handle it.
1264 init_request_from_bio(req
, bio
);
1266 spin_lock_irq(q
->queue_lock
);
1267 if (test_bit(QUEUE_FLAG_SAME_COMP
, &q
->queue_flags
) ||
1268 bio_flagged(bio
, BIO_CPU_AFFINE
))
1269 req
->cpu
= blk_cpu_to_group(smp_processor_id());
1270 if (queue_should_plug(q
) && elv_queue_empty(q
))
1272 add_request(q
, req
);
1274 if (unplug
|| !queue_should_plug(q
))
1275 __generic_unplug_device(q
);
1276 spin_unlock_irq(q
->queue_lock
);
1281 * If bio->bi_dev is a partition, remap the location
1283 static inline void blk_partition_remap(struct bio
*bio
)
1285 struct block_device
*bdev
= bio
->bi_bdev
;
1287 if (bio_sectors(bio
) && bdev
!= bdev
->bd_contains
) {
1288 struct hd_struct
*p
= bdev
->bd_part
;
1290 bio
->bi_sector
+= p
->start_sect
;
1291 bio
->bi_bdev
= bdev
->bd_contains
;
1293 trace_block_remap(bdev_get_queue(bio
->bi_bdev
), bio
,
1295 bio
->bi_sector
- p
->start_sect
);
1299 static void handle_bad_sector(struct bio
*bio
)
1301 char b
[BDEVNAME_SIZE
];
1303 printk(KERN_INFO
"attempt to access beyond end of device\n");
1304 printk(KERN_INFO
"%s: rw=%ld, want=%Lu, limit=%Lu\n",
1305 bdevname(bio
->bi_bdev
, b
),
1307 (unsigned long long)bio
->bi_sector
+ bio_sectors(bio
),
1308 (long long)(bio
->bi_bdev
->bd_inode
->i_size
>> 9));
1310 set_bit(BIO_EOF
, &bio
->bi_flags
);
1313 #ifdef CONFIG_FAIL_MAKE_REQUEST
1315 static DECLARE_FAULT_ATTR(fail_make_request
);
1317 static int __init
setup_fail_make_request(char *str
)
1319 return setup_fault_attr(&fail_make_request
, str
);
1321 __setup("fail_make_request=", setup_fail_make_request
);
1323 static int should_fail_request(struct bio
*bio
)
1325 struct hd_struct
*part
= bio
->bi_bdev
->bd_part
;
1327 if (part_to_disk(part
)->part0
.make_it_fail
|| part
->make_it_fail
)
1328 return should_fail(&fail_make_request
, bio
->bi_size
);
1333 static int __init
fail_make_request_debugfs(void)
1335 return init_fault_attr_dentries(&fail_make_request
,
1336 "fail_make_request");
1339 late_initcall(fail_make_request_debugfs
);
1341 #else /* CONFIG_FAIL_MAKE_REQUEST */
1343 static inline int should_fail_request(struct bio
*bio
)
1348 #endif /* CONFIG_FAIL_MAKE_REQUEST */
1351 * Check whether this bio extends beyond the end of the device.
1353 static inline int bio_check_eod(struct bio
*bio
, unsigned int nr_sectors
)
1360 /* Test device or partition size, when known. */
1361 maxsector
= bio
->bi_bdev
->bd_inode
->i_size
>> 9;
1363 sector_t sector
= bio
->bi_sector
;
1365 if (maxsector
< nr_sectors
|| maxsector
- nr_sectors
< sector
) {
1367 * This may well happen - the kernel calls bread()
1368 * without checking the size of the device, e.g., when
1369 * mounting a device.
1371 handle_bad_sector(bio
);
1380 * generic_make_request - hand a buffer to its device driver for I/O
1381 * @bio: The bio describing the location in memory and on the device.
1383 * generic_make_request() is used to make I/O requests of block
1384 * devices. It is passed a &struct bio, which describes the I/O that needs
1387 * generic_make_request() does not return any status. The
1388 * success/failure status of the request, along with notification of
1389 * completion, is delivered asynchronously through the bio->bi_end_io
1390 * function described (one day) else where.
1392 * The caller of generic_make_request must make sure that bi_io_vec
1393 * are set to describe the memory buffer, and that bi_dev and bi_sector are
1394 * set to describe the device address, and the
1395 * bi_end_io and optionally bi_private are set to describe how
1396 * completion notification should be signaled.
1398 * generic_make_request and the drivers it calls may use bi_next if this
1399 * bio happens to be merged with someone else, and may change bi_dev and
1400 * bi_sector for remaps as it sees fit. So the values of these fields
1401 * should NOT be depended on after the call to generic_make_request.
1403 static inline void __generic_make_request(struct bio
*bio
)
1405 struct request_queue
*q
;
1406 sector_t old_sector
;
1407 int ret
, nr_sectors
= bio_sectors(bio
);
1413 if (bio_check_eod(bio
, nr_sectors
))
1417 * Resolve the mapping until finished. (drivers are
1418 * still free to implement/resolve their own stacking
1419 * by explicitly returning 0)
1421 * NOTE: we don't repeat the blk_size check for each new device.
1422 * Stacking drivers are expected to know what they are doing.
1427 char b
[BDEVNAME_SIZE
];
1429 q
= bdev_get_queue(bio
->bi_bdev
);
1432 "generic_make_request: Trying to access "
1433 "nonexistent block-device %s (%Lu)\n",
1434 bdevname(bio
->bi_bdev
, b
),
1435 (long long) bio
->bi_sector
);
1439 if (unlikely(nr_sectors
> queue_max_hw_sectors(q
))) {
1440 printk(KERN_ERR
"bio too big device %s (%u > %u)\n",
1441 bdevname(bio
->bi_bdev
, b
),
1443 queue_max_hw_sectors(q
));
1447 if (unlikely(test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
)))
1450 if (should_fail_request(bio
))
1454 * If this device has partitions, remap block n
1455 * of partition p to block n+start(p) of the disk.
1457 blk_partition_remap(bio
);
1459 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
))
1462 if (old_sector
!= -1)
1463 trace_block_remap(q
, bio
, old_dev
, old_sector
);
1465 trace_block_bio_queue(q
, bio
);
1467 old_sector
= bio
->bi_sector
;
1468 old_dev
= bio
->bi_bdev
->bd_dev
;
1470 if (bio_check_eod(bio
, nr_sectors
))
1473 if (bio_rw_flagged(bio
, BIO_RW_DISCARD
) &&
1474 !q
->prepare_discard_fn
) {
1479 ret
= q
->make_request_fn(q
, bio
);
1485 bio_endio(bio
, err
);
1489 * We only want one ->make_request_fn to be active at a time,
1490 * else stack usage with stacked devices could be a problem.
1491 * So use current->bio_{list,tail} to keep a list of requests
1492 * submited by a make_request_fn function.
1493 * current->bio_tail is also used as a flag to say if
1494 * generic_make_request is currently active in this task or not.
1495 * If it is NULL, then no make_request is active. If it is non-NULL,
1496 * then a make_request is active, and new requests should be added
1499 void generic_make_request(struct bio
*bio
)
1501 if (current
->bio_tail
) {
1502 /* make_request is active */
1503 *(current
->bio_tail
) = bio
;
1504 bio
->bi_next
= NULL
;
1505 current
->bio_tail
= &bio
->bi_next
;
1508 /* following loop may be a bit non-obvious, and so deserves some
1510 * Before entering the loop, bio->bi_next is NULL (as all callers
1511 * ensure that) so we have a list with a single bio.
1512 * We pretend that we have just taken it off a longer list, so
1513 * we assign bio_list to the next (which is NULL) and bio_tail
1514 * to &bio_list, thus initialising the bio_list of new bios to be
1515 * added. __generic_make_request may indeed add some more bios
1516 * through a recursive call to generic_make_request. If it
1517 * did, we find a non-NULL value in bio_list and re-enter the loop
1518 * from the top. In this case we really did just take the bio
1519 * of the top of the list (no pretending) and so fixup bio_list and
1520 * bio_tail or bi_next, and call into __generic_make_request again.
1522 * The loop was structured like this to make only one call to
1523 * __generic_make_request (which is important as it is large and
1524 * inlined) and to keep the structure simple.
1526 BUG_ON(bio
->bi_next
);
1528 current
->bio_list
= bio
->bi_next
;
1529 if (bio
->bi_next
== NULL
)
1530 current
->bio_tail
= ¤t
->bio_list
;
1532 bio
->bi_next
= NULL
;
1533 __generic_make_request(bio
);
1534 bio
= current
->bio_list
;
1536 current
->bio_tail
= NULL
; /* deactivate */
1538 EXPORT_SYMBOL(generic_make_request
);
1541 * submit_bio - submit a bio to the block device layer for I/O
1542 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
1543 * @bio: The &struct bio which describes the I/O
1545 * submit_bio() is very similar in purpose to generic_make_request(), and
1546 * uses that function to do most of the work. Both are fairly rough
1547 * interfaces; @bio must be presetup and ready for I/O.
1550 void submit_bio(int rw
, struct bio
*bio
)
1552 int count
= bio_sectors(bio
);
1557 * If it's a regular read/write or a barrier with data attached,
1558 * go through the normal accounting stuff before submission.
1560 if (bio_has_data(bio
)) {
1562 count_vm_events(PGPGOUT
, count
);
1564 task_io_account_read(bio
->bi_size
);
1565 count_vm_events(PGPGIN
, count
);
1568 if (unlikely(block_dump
)) {
1569 char b
[BDEVNAME_SIZE
];
1570 printk(KERN_DEBUG
"%s(%d): %s block %Lu on %s\n",
1571 current
->comm
, task_pid_nr(current
),
1572 (rw
& WRITE
) ? "WRITE" : "READ",
1573 (unsigned long long)bio
->bi_sector
,
1574 bdevname(bio
->bi_bdev
, b
));
1578 generic_make_request(bio
);
1580 EXPORT_SYMBOL(submit_bio
);
1583 * blk_rq_check_limits - Helper function to check a request for the queue limit
1585 * @rq: the request being checked
1588 * @rq may have been made based on weaker limitations of upper-level queues
1589 * in request stacking drivers, and it may violate the limitation of @q.
1590 * Since the block layer and the underlying device driver trust @rq
1591 * after it is inserted to @q, it should be checked against @q before
1592 * the insertion using this generic function.
1594 * This function should also be useful for request stacking drivers
1595 * in some cases below, so export this fuction.
1596 * Request stacking drivers like request-based dm may change the queue
1597 * limits while requests are in the queue (e.g. dm's table swapping).
1598 * Such request stacking drivers should check those requests agaist
1599 * the new queue limits again when they dispatch those requests,
1600 * although such checkings are also done against the old queue limits
1601 * when submitting requests.
1603 int blk_rq_check_limits(struct request_queue
*q
, struct request
*rq
)
1605 if (blk_rq_sectors(rq
) > queue_max_sectors(q
) ||
1606 blk_rq_bytes(rq
) > queue_max_hw_sectors(q
) << 9) {
1607 printk(KERN_ERR
"%s: over max size limit.\n", __func__
);
1612 * queue's settings related to segment counting like q->bounce_pfn
1613 * may differ from that of other stacking queues.
1614 * Recalculate it to check the request correctly on this queue's
1617 blk_recalc_rq_segments(rq
);
1618 if (rq
->nr_phys_segments
> queue_max_phys_segments(q
) ||
1619 rq
->nr_phys_segments
> queue_max_hw_segments(q
)) {
1620 printk(KERN_ERR
"%s: over max segments limit.\n", __func__
);
1626 EXPORT_SYMBOL_GPL(blk_rq_check_limits
);
1629 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
1630 * @q: the queue to submit the request
1631 * @rq: the request being queued
1633 int blk_insert_cloned_request(struct request_queue
*q
, struct request
*rq
)
1635 unsigned long flags
;
1637 if (blk_rq_check_limits(q
, rq
))
1640 #ifdef CONFIG_FAIL_MAKE_REQUEST
1641 if (rq
->rq_disk
&& rq
->rq_disk
->part0
.make_it_fail
&&
1642 should_fail(&fail_make_request
, blk_rq_bytes(rq
)))
1646 spin_lock_irqsave(q
->queue_lock
, flags
);
1649 * Submitting request must be dequeued before calling this function
1650 * because it will be linked to another request_queue
1652 BUG_ON(blk_queued_rq(rq
));
1654 drive_stat_acct(rq
, 1);
1655 __elv_add_request(q
, rq
, ELEVATOR_INSERT_BACK
, 0);
1657 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1661 EXPORT_SYMBOL_GPL(blk_insert_cloned_request
);
1664 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
1665 * @rq: request to examine
1668 * A request could be merge of IOs which require different failure
1669 * handling. This function determines the number of bytes which
1670 * can be failed from the beginning of the request without
1671 * crossing into area which need to be retried further.
1674 * The number of bytes to fail.
1677 * queue_lock must be held.
1679 unsigned int blk_rq_err_bytes(const struct request
*rq
)
1681 unsigned int ff
= rq
->cmd_flags
& REQ_FAILFAST_MASK
;
1682 unsigned int bytes
= 0;
1685 if (!(rq
->cmd_flags
& REQ_MIXED_MERGE
))
1686 return blk_rq_bytes(rq
);
1689 * Currently the only 'mixing' which can happen is between
1690 * different fastfail types. We can safely fail portions
1691 * which have all the failfast bits that the first one has -
1692 * the ones which are at least as eager to fail as the first
1695 for (bio
= rq
->bio
; bio
; bio
= bio
->bi_next
) {
1696 if ((bio
->bi_rw
& ff
) != ff
)
1698 bytes
+= bio
->bi_size
;
1701 /* this could lead to infinite loop */
1702 BUG_ON(blk_rq_bytes(rq
) && !bytes
);
1705 EXPORT_SYMBOL_GPL(blk_rq_err_bytes
);
1707 static void blk_account_io_completion(struct request
*req
, unsigned int bytes
)
1709 if (blk_do_io_stat(req
)) {
1710 const int rw
= rq_data_dir(req
);
1711 struct hd_struct
*part
;
1714 cpu
= part_stat_lock();
1715 part
= disk_map_sector_rcu(req
->rq_disk
, blk_rq_pos(req
));
1716 part_stat_add(cpu
, part
, sectors
[rw
], bytes
>> 9);
1721 static void blk_account_io_done(struct request
*req
)
1724 * Account IO completion. bar_rq isn't accounted as a normal
1725 * IO on queueing nor completion. Accounting the containing
1726 * request is enough.
1728 if (blk_do_io_stat(req
) && req
!= &req
->q
->bar_rq
) {
1729 unsigned long duration
= jiffies
- req
->start_time
;
1730 const int rw
= rq_data_dir(req
);
1731 struct hd_struct
*part
;
1734 cpu
= part_stat_lock();
1735 part
= disk_map_sector_rcu(req
->rq_disk
, blk_rq_pos(req
));
1737 part_stat_inc(cpu
, part
, ios
[rw
]);
1738 part_stat_add(cpu
, part
, ticks
[rw
], duration
);
1739 part_round_stats(cpu
, part
);
1740 part_dec_in_flight(part
);
1747 * blk_peek_request - peek at the top of a request queue
1748 * @q: request queue to peek at
1751 * Return the request at the top of @q. The returned request
1752 * should be started using blk_start_request() before LLD starts
1756 * Pointer to the request at the top of @q if available. Null
1760 * queue_lock must be held.
1762 struct request
*blk_peek_request(struct request_queue
*q
)
1767 while ((rq
= __elv_next_request(q
)) != NULL
) {
1768 if (!(rq
->cmd_flags
& REQ_STARTED
)) {
1770 * This is the first time the device driver
1771 * sees this request (possibly after
1772 * requeueing). Notify IO scheduler.
1774 if (blk_sorted_rq(rq
))
1775 elv_activate_rq(q
, rq
);
1778 * just mark as started even if we don't start
1779 * it, a request that has been delayed should
1780 * not be passed by new incoming requests
1782 rq
->cmd_flags
|= REQ_STARTED
;
1783 trace_block_rq_issue(q
, rq
);
1786 if (!q
->boundary_rq
|| q
->boundary_rq
== rq
) {
1787 q
->end_sector
= rq_end_sector(rq
);
1788 q
->boundary_rq
= NULL
;
1791 if (rq
->cmd_flags
& REQ_DONTPREP
)
1794 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
1796 * make sure space for the drain appears we
1797 * know we can do this because max_hw_segments
1798 * has been adjusted to be one fewer than the
1801 rq
->nr_phys_segments
++;
1807 ret
= q
->prep_rq_fn(q
, rq
);
1808 if (ret
== BLKPREP_OK
) {
1810 } else if (ret
== BLKPREP_DEFER
) {
1812 * the request may have been (partially) prepped.
1813 * we need to keep this request in the front to
1814 * avoid resource deadlock. REQ_STARTED will
1815 * prevent other fs requests from passing this one.
1817 if (q
->dma_drain_size
&& blk_rq_bytes(rq
) &&
1818 !(rq
->cmd_flags
& REQ_DONTPREP
)) {
1820 * remove the space for the drain we added
1821 * so that we don't add it again
1823 --rq
->nr_phys_segments
;
1828 } else if (ret
== BLKPREP_KILL
) {
1829 rq
->cmd_flags
|= REQ_QUIET
;
1831 * Mark this request as started so we don't trigger
1832 * any debug logic in the end I/O path.
1834 blk_start_request(rq
);
1835 __blk_end_request_all(rq
, -EIO
);
1837 printk(KERN_ERR
"%s: bad return=%d\n", __func__
, ret
);
1844 EXPORT_SYMBOL(blk_peek_request
);
1846 void blk_dequeue_request(struct request
*rq
)
1848 struct request_queue
*q
= rq
->q
;
1850 BUG_ON(list_empty(&rq
->queuelist
));
1851 BUG_ON(ELV_ON_HASH(rq
));
1853 list_del_init(&rq
->queuelist
);
1856 * the time frame between a request being removed from the lists
1857 * and to it is freed is accounted as io that is in progress at
1860 if (blk_account_rq(rq
)) {
1861 q
->in_flight
[rq_is_sync(rq
)]++;
1863 * Mark this device as supporting hardware queuing, if
1864 * we have more IOs in flight than 4.
1866 if (!blk_queue_queuing(q
) && queue_in_flight(q
) > 4)
1867 set_bit(QUEUE_FLAG_CQ
, &q
->queue_flags
);
1872 * blk_start_request - start request processing on the driver
1873 * @req: request to dequeue
1876 * Dequeue @req and start timeout timer on it. This hands off the
1877 * request to the driver.
1879 * Block internal functions which don't want to start timer should
1880 * call blk_dequeue_request().
1883 * queue_lock must be held.
1885 void blk_start_request(struct request
*req
)
1887 blk_dequeue_request(req
);
1890 * We are now handing the request to the hardware, initialize
1891 * resid_len to full count and add the timeout handler.
1893 req
->resid_len
= blk_rq_bytes(req
);
1894 if (unlikely(blk_bidi_rq(req
)))
1895 req
->next_rq
->resid_len
= blk_rq_bytes(req
->next_rq
);
1899 EXPORT_SYMBOL(blk_start_request
);
1902 * blk_fetch_request - fetch a request from a request queue
1903 * @q: request queue to fetch a request from
1906 * Return the request at the top of @q. The request is started on
1907 * return and LLD can start processing it immediately.
1910 * Pointer to the request at the top of @q if available. Null
1914 * queue_lock must be held.
1916 struct request
*blk_fetch_request(struct request_queue
*q
)
1920 rq
= blk_peek_request(q
);
1922 blk_start_request(rq
);
1925 EXPORT_SYMBOL(blk_fetch_request
);
1928 * blk_update_request - Special helper function for request stacking drivers
1929 * @req: the request being processed
1930 * @error: %0 for success, < %0 for error
1931 * @nr_bytes: number of bytes to complete @req
1934 * Ends I/O on a number of bytes attached to @req, but doesn't complete
1935 * the request structure even if @req doesn't have leftover.
1936 * If @req has leftover, sets it up for the next range of segments.
1938 * This special helper function is only for request stacking drivers
1939 * (e.g. request-based dm) so that they can handle partial completion.
1940 * Actual device drivers should use blk_end_request instead.
1942 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
1943 * %false return from this function.
1946 * %false - this request doesn't have any more data
1947 * %true - this request has more data
1949 bool blk_update_request(struct request
*req
, int error
, unsigned int nr_bytes
)
1951 int total_bytes
, bio_nbytes
, next_idx
= 0;
1957 trace_block_rq_complete(req
->q
, req
);
1960 * For fs requests, rq is just carrier of independent bio's
1961 * and each partial completion should be handled separately.
1962 * Reset per-request error on each partial completion.
1964 * TODO: tj: This is too subtle. It would be better to let
1965 * low level drivers do what they see fit.
1967 if (blk_fs_request(req
))
1970 if (error
&& (blk_fs_request(req
) && !(req
->cmd_flags
& REQ_QUIET
))) {
1971 printk(KERN_ERR
"end_request: I/O error, dev %s, sector %llu\n",
1972 req
->rq_disk
? req
->rq_disk
->disk_name
: "?",
1973 (unsigned long long)blk_rq_pos(req
));
1976 blk_account_io_completion(req
, nr_bytes
);
1978 total_bytes
= bio_nbytes
= 0;
1979 while ((bio
= req
->bio
) != NULL
) {
1982 if (nr_bytes
>= bio
->bi_size
) {
1983 req
->bio
= bio
->bi_next
;
1984 nbytes
= bio
->bi_size
;
1985 req_bio_endio(req
, bio
, nbytes
, error
);
1989 int idx
= bio
->bi_idx
+ next_idx
;
1991 if (unlikely(idx
>= bio
->bi_vcnt
)) {
1992 blk_dump_rq_flags(req
, "__end_that");
1993 printk(KERN_ERR
"%s: bio idx %d >= vcnt %d\n",
1994 __func__
, idx
, bio
->bi_vcnt
);
1998 nbytes
= bio_iovec_idx(bio
, idx
)->bv_len
;
1999 BIO_BUG_ON(nbytes
> bio
->bi_size
);
2002 * not a complete bvec done
2004 if (unlikely(nbytes
> nr_bytes
)) {
2005 bio_nbytes
+= nr_bytes
;
2006 total_bytes
+= nr_bytes
;
2011 * advance to the next vector
2014 bio_nbytes
+= nbytes
;
2017 total_bytes
+= nbytes
;
2023 * end more in this run, or just return 'not-done'
2025 if (unlikely(nr_bytes
<= 0))
2035 * Reset counters so that the request stacking driver
2036 * can find how many bytes remain in the request
2039 req
->__data_len
= 0;
2044 * if the request wasn't completed, update state
2047 req_bio_endio(req
, bio
, bio_nbytes
, error
);
2048 bio
->bi_idx
+= next_idx
;
2049 bio_iovec(bio
)->bv_offset
+= nr_bytes
;
2050 bio_iovec(bio
)->bv_len
-= nr_bytes
;
2053 req
->__data_len
-= total_bytes
;
2054 req
->buffer
= bio_data(req
->bio
);
2056 /* update sector only for requests with clear definition of sector */
2057 if (blk_fs_request(req
) || blk_discard_rq(req
))
2058 req
->__sector
+= total_bytes
>> 9;
2060 /* mixed attributes always follow the first bio */
2061 if (req
->cmd_flags
& REQ_MIXED_MERGE
) {
2062 req
->cmd_flags
&= ~REQ_FAILFAST_MASK
;
2063 req
->cmd_flags
|= req
->bio
->bi_rw
& REQ_FAILFAST_MASK
;
2067 * If total number of sectors is less than the first segment
2068 * size, something has gone terribly wrong.
2070 if (blk_rq_bytes(req
) < blk_rq_cur_bytes(req
)) {
2071 printk(KERN_ERR
"blk: request botched\n");
2072 req
->__data_len
= blk_rq_cur_bytes(req
);
2075 /* recalculate the number of segments */
2076 blk_recalc_rq_segments(req
);
2080 EXPORT_SYMBOL_GPL(blk_update_request
);
2082 static bool blk_update_bidi_request(struct request
*rq
, int error
,
2083 unsigned int nr_bytes
,
2084 unsigned int bidi_bytes
)
2086 if (blk_update_request(rq
, error
, nr_bytes
))
2089 /* Bidi request must be completed as a whole */
2090 if (unlikely(blk_bidi_rq(rq
)) &&
2091 blk_update_request(rq
->next_rq
, error
, bidi_bytes
))
2094 add_disk_randomness(rq
->rq_disk
);
2100 * queue lock must be held
2102 static void blk_finish_request(struct request
*req
, int error
)
2104 if (blk_rq_tagged(req
))
2105 blk_queue_end_tag(req
->q
, req
);
2107 BUG_ON(blk_queued_rq(req
));
2109 if (unlikely(laptop_mode
) && blk_fs_request(req
))
2110 laptop_io_completion();
2112 blk_delete_timer(req
);
2114 blk_account_io_done(req
);
2117 req
->end_io(req
, error
);
2119 if (blk_bidi_rq(req
))
2120 __blk_put_request(req
->next_rq
->q
, req
->next_rq
);
2122 __blk_put_request(req
->q
, req
);
2127 * blk_end_bidi_request - Complete a bidi request
2128 * @rq: the request to complete
2129 * @error: %0 for success, < %0 for error
2130 * @nr_bytes: number of bytes to complete @rq
2131 * @bidi_bytes: number of bytes to complete @rq->next_rq
2134 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2135 * Drivers that supports bidi can safely call this member for any
2136 * type of request, bidi or uni. In the later case @bidi_bytes is
2140 * %false - we are done with this request
2141 * %true - still buffers pending for this request
2143 static bool blk_end_bidi_request(struct request
*rq
, int error
,
2144 unsigned int nr_bytes
, unsigned int bidi_bytes
)
2146 struct request_queue
*q
= rq
->q
;
2147 unsigned long flags
;
2149 if (blk_update_bidi_request(rq
, error
, nr_bytes
, bidi_bytes
))
2152 spin_lock_irqsave(q
->queue_lock
, flags
);
2153 blk_finish_request(rq
, error
);
2154 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2160 * __blk_end_bidi_request - Complete a bidi request with queue lock held
2161 * @rq: the request to complete
2162 * @error: %0 for success, < %0 for error
2163 * @nr_bytes: number of bytes to complete @rq
2164 * @bidi_bytes: number of bytes to complete @rq->next_rq
2167 * Identical to blk_end_bidi_request() except that queue lock is
2168 * assumed to be locked on entry and remains so on return.
2171 * %false - we are done with this request
2172 * %true - still buffers pending for this request
2174 static bool __blk_end_bidi_request(struct request
*rq
, int error
,
2175 unsigned int nr_bytes
, unsigned int bidi_bytes
)
2177 if (blk_update_bidi_request(rq
, error
, nr_bytes
, bidi_bytes
))
2180 blk_finish_request(rq
, error
);
2186 * blk_end_request - Helper function for drivers to complete the request.
2187 * @rq: the request being processed
2188 * @error: %0 for success, < %0 for error
2189 * @nr_bytes: number of bytes to complete
2192 * Ends I/O on a number of bytes attached to @rq.
2193 * If @rq has leftover, sets it up for the next range of segments.
2196 * %false - we are done with this request
2197 * %true - still buffers pending for this request
2199 bool blk_end_request(struct request
*rq
, int error
, unsigned int nr_bytes
)
2201 return blk_end_bidi_request(rq
, error
, nr_bytes
, 0);
2203 EXPORT_SYMBOL(blk_end_request
);
2206 * blk_end_request_all - Helper function for drives to finish the request.
2207 * @rq: the request to finish
2208 * @error: %0 for success, < %0 for error
2211 * Completely finish @rq.
2213 void blk_end_request_all(struct request
*rq
, int error
)
2216 unsigned int bidi_bytes
= 0;
2218 if (unlikely(blk_bidi_rq(rq
)))
2219 bidi_bytes
= blk_rq_bytes(rq
->next_rq
);
2221 pending
= blk_end_bidi_request(rq
, error
, blk_rq_bytes(rq
), bidi_bytes
);
2224 EXPORT_SYMBOL(blk_end_request_all
);
2227 * blk_end_request_cur - Helper function to finish the current request chunk.
2228 * @rq: the request to finish the current chunk for
2229 * @error: %0 for success, < %0 for error
2232 * Complete the current consecutively mapped chunk from @rq.
2235 * %false - we are done with this request
2236 * %true - still buffers pending for this request
2238 bool blk_end_request_cur(struct request
*rq
, int error
)
2240 return blk_end_request(rq
, error
, blk_rq_cur_bytes(rq
));
2242 EXPORT_SYMBOL(blk_end_request_cur
);
2245 * blk_end_request_err - Finish a request till the next failure boundary.
2246 * @rq: the request to finish till the next failure boundary for
2247 * @error: must be negative errno
2250 * Complete @rq till the next failure boundary.
2253 * %false - we are done with this request
2254 * %true - still buffers pending for this request
2256 bool blk_end_request_err(struct request
*rq
, int error
)
2258 WARN_ON(error
>= 0);
2259 return blk_end_request(rq
, error
, blk_rq_err_bytes(rq
));
2261 EXPORT_SYMBOL_GPL(blk_end_request_err
);
2264 * __blk_end_request - Helper function for drivers to complete the request.
2265 * @rq: the request being processed
2266 * @error: %0 for success, < %0 for error
2267 * @nr_bytes: number of bytes to complete
2270 * Must be called with queue lock held unlike blk_end_request().
2273 * %false - we are done with this request
2274 * %true - still buffers pending for this request
2276 bool __blk_end_request(struct request
*rq
, int error
, unsigned int nr_bytes
)
2278 return __blk_end_bidi_request(rq
, error
, nr_bytes
, 0);
2280 EXPORT_SYMBOL(__blk_end_request
);
2283 * __blk_end_request_all - Helper function for drives to finish the request.
2284 * @rq: the request to finish
2285 * @error: %0 for success, < %0 for error
2288 * Completely finish @rq. Must be called with queue lock held.
2290 void __blk_end_request_all(struct request
*rq
, int error
)
2293 unsigned int bidi_bytes
= 0;
2295 if (unlikely(blk_bidi_rq(rq
)))
2296 bidi_bytes
= blk_rq_bytes(rq
->next_rq
);
2298 pending
= __blk_end_bidi_request(rq
, error
, blk_rq_bytes(rq
), bidi_bytes
);
2301 EXPORT_SYMBOL(__blk_end_request_all
);
2304 * __blk_end_request_cur - Helper function to finish the current request chunk.
2305 * @rq: the request to finish the current chunk for
2306 * @error: %0 for success, < %0 for error
2309 * Complete the current consecutively mapped chunk from @rq. Must
2310 * be called with queue lock held.
2313 * %false - we are done with this request
2314 * %true - still buffers pending for this request
2316 bool __blk_end_request_cur(struct request
*rq
, int error
)
2318 return __blk_end_request(rq
, error
, blk_rq_cur_bytes(rq
));
2320 EXPORT_SYMBOL(__blk_end_request_cur
);
2323 * __blk_end_request_err - Finish a request till the next failure boundary.
2324 * @rq: the request to finish till the next failure boundary for
2325 * @error: must be negative errno
2328 * Complete @rq till the next failure boundary. Must be called
2329 * with queue lock held.
2332 * %false - we are done with this request
2333 * %true - still buffers pending for this request
2335 bool __blk_end_request_err(struct request
*rq
, int error
)
2337 WARN_ON(error
>= 0);
2338 return __blk_end_request(rq
, error
, blk_rq_err_bytes(rq
));
2340 EXPORT_SYMBOL_GPL(__blk_end_request_err
);
2342 void blk_rq_bio_prep(struct request_queue
*q
, struct request
*rq
,
2345 /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */
2346 rq
->cmd_flags
|= bio
->bi_rw
& REQ_RW
;
2348 if (bio_has_data(bio
)) {
2349 rq
->nr_phys_segments
= bio_phys_segments(q
, bio
);
2350 rq
->buffer
= bio_data(bio
);
2352 rq
->__data_len
= bio
->bi_size
;
2353 rq
->bio
= rq
->biotail
= bio
;
2356 rq
->rq_disk
= bio
->bi_bdev
->bd_disk
;
2360 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
2361 * @q : the queue of the device being checked
2364 * Check if underlying low-level drivers of a device are busy.
2365 * If the drivers want to export their busy state, they must set own
2366 * exporting function using blk_queue_lld_busy() first.
2368 * Basically, this function is used only by request stacking drivers
2369 * to stop dispatching requests to underlying devices when underlying
2370 * devices are busy. This behavior helps more I/O merging on the queue
2371 * of the request stacking driver and prevents I/O throughput regression
2372 * on burst I/O load.
2375 * 0 - Not busy (The request stacking driver should dispatch request)
2376 * 1 - Busy (The request stacking driver should stop dispatching request)
2378 int blk_lld_busy(struct request_queue
*q
)
2381 return q
->lld_busy_fn(q
);
2385 EXPORT_SYMBOL_GPL(blk_lld_busy
);
2388 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
2389 * @rq: the clone request to be cleaned up
2392 * Free all bios in @rq for a cloned request.
2394 void blk_rq_unprep_clone(struct request
*rq
)
2398 while ((bio
= rq
->bio
) != NULL
) {
2399 rq
->bio
= bio
->bi_next
;
2404 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone
);
2407 * Copy attributes of the original request to the clone request.
2408 * The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not copied.
2410 static void __blk_rq_prep_clone(struct request
*dst
, struct request
*src
)
2412 dst
->cpu
= src
->cpu
;
2413 dst
->cmd_flags
= (rq_data_dir(src
) | REQ_NOMERGE
);
2414 dst
->cmd_type
= src
->cmd_type
;
2415 dst
->__sector
= blk_rq_pos(src
);
2416 dst
->__data_len
= blk_rq_bytes(src
);
2417 dst
->nr_phys_segments
= src
->nr_phys_segments
;
2418 dst
->ioprio
= src
->ioprio
;
2419 dst
->extra_len
= src
->extra_len
;
2423 * blk_rq_prep_clone - Helper function to setup clone request
2424 * @rq: the request to be setup
2425 * @rq_src: original request to be cloned
2426 * @bs: bio_set that bios for clone are allocated from
2427 * @gfp_mask: memory allocation mask for bio
2428 * @bio_ctr: setup function to be called for each clone bio.
2429 * Returns %0 for success, non %0 for failure.
2430 * @data: private data to be passed to @bio_ctr
2433 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
2434 * The actual data parts of @rq_src (e.g. ->cmd, ->buffer, ->sense)
2435 * are not copied, and copying such parts is the caller's responsibility.
2436 * Also, pages which the original bios are pointing to are not copied
2437 * and the cloned bios just point same pages.
2438 * So cloned bios must be completed before original bios, which means
2439 * the caller must complete @rq before @rq_src.
2441 int blk_rq_prep_clone(struct request
*rq
, struct request
*rq_src
,
2442 struct bio_set
*bs
, gfp_t gfp_mask
,
2443 int (*bio_ctr
)(struct bio
*, struct bio
*, void *),
2446 struct bio
*bio
, *bio_src
;
2451 blk_rq_init(NULL
, rq
);
2453 __rq_for_each_bio(bio_src
, rq_src
) {
2454 bio
= bio_alloc_bioset(gfp_mask
, bio_src
->bi_max_vecs
, bs
);
2458 __bio_clone(bio
, bio_src
);
2460 if (bio_integrity(bio_src
) &&
2461 bio_integrity_clone(bio
, bio_src
, gfp_mask
, bs
))
2464 if (bio_ctr
&& bio_ctr(bio
, bio_src
, data
))
2468 rq
->biotail
->bi_next
= bio
;
2471 rq
->bio
= rq
->biotail
= bio
;
2474 __blk_rq_prep_clone(rq
, rq_src
);
2481 blk_rq_unprep_clone(rq
);
2485 EXPORT_SYMBOL_GPL(blk_rq_prep_clone
);
2487 int kblockd_schedule_work(struct request_queue
*q
, struct work_struct
*work
)
2489 return queue_work(kblockd_workqueue
, work
);
2491 EXPORT_SYMBOL(kblockd_schedule_work
);
2493 int __init
blk_dev_init(void)
2495 BUILD_BUG_ON(__REQ_NR_BITS
> 8 *
2496 sizeof(((struct request
*)0)->cmd_flags
));
2498 kblockd_workqueue
= create_workqueue("kblockd");
2499 if (!kblockd_workqueue
)
2500 panic("Failed to create kblockd\n");
2502 request_cachep
= kmem_cache_create("blkdev_requests",
2503 sizeof(struct request
), 0, SLAB_PANIC
, NULL
);
2505 blk_requestq_cachep
= kmem_cache_create("blkdev_queue",
2506 sizeof(struct request_queue
), 0, SLAB_PANIC
, NULL
);