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> - July2000
7 * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
11 * This handles all read/write requests to block devices
13 #include <linux/config.h>
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/bootmem.h> /* for max_pfn/max_low_pfn */
25 #include <linux/completion.h>
26 #include <linux/slab.h>
27 #include <linux/swap.h>
28 #include <linux/writeback.h>
29 #include <linux/interrupt.h>
30 #include <linux/cpu.h>
35 #include <scsi/scsi_cmnd.h>
37 static void blk_unplug_work(void *data
);
38 static void blk_unplug_timeout(unsigned long data
);
39 static void drive_stat_acct(struct request
*rq
, int nr_sectors
, int new_io
);
40 static void init_request_from_bio(struct request
*req
, struct bio
*bio
);
41 static int __make_request(request_queue_t
*q
, struct bio
*bio
);
44 * For the allocated request tables
46 static kmem_cache_t
*request_cachep
;
49 * For queue allocation
51 static kmem_cache_t
*requestq_cachep
;
54 * For io context allocations
56 static kmem_cache_t
*iocontext_cachep
;
58 static wait_queue_head_t congestion_wqh
[2] = {
59 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh
[0]),
60 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh
[1])
64 * Controlling structure to kblockd
66 static struct workqueue_struct
*kblockd_workqueue
;
68 unsigned long blk_max_low_pfn
, blk_max_pfn
;
70 EXPORT_SYMBOL(blk_max_low_pfn
);
71 EXPORT_SYMBOL(blk_max_pfn
);
73 static DEFINE_PER_CPU(struct list_head
, blk_cpu_done
);
75 /* Amount of time in which a process may batch requests */
76 #define BLK_BATCH_TIME (HZ/50UL)
78 /* Number of requests a "batching" process may submit */
79 #define BLK_BATCH_REQ 32
82 * Return the threshold (number of used requests) at which the queue is
83 * considered to be congested. It include a little hysteresis to keep the
84 * context switch rate down.
86 static inline int queue_congestion_on_threshold(struct request_queue
*q
)
88 return q
->nr_congestion_on
;
92 * The threshold at which a queue is considered to be uncongested
94 static inline int queue_congestion_off_threshold(struct request_queue
*q
)
96 return q
->nr_congestion_off
;
99 static void blk_queue_congestion_threshold(struct request_queue
*q
)
103 nr
= q
->nr_requests
- (q
->nr_requests
/ 8) + 1;
104 if (nr
> q
->nr_requests
)
106 q
->nr_congestion_on
= nr
;
108 nr
= q
->nr_requests
- (q
->nr_requests
/ 8) - (q
->nr_requests
/ 16) - 1;
111 q
->nr_congestion_off
= nr
;
115 * A queue has just exitted congestion. Note this in the global counter of
116 * congested queues, and wake up anyone who was waiting for requests to be
119 static void clear_queue_congested(request_queue_t
*q
, int rw
)
122 wait_queue_head_t
*wqh
= &congestion_wqh
[rw
];
124 bit
= (rw
== WRITE
) ? BDI_write_congested
: BDI_read_congested
;
125 clear_bit(bit
, &q
->backing_dev_info
.state
);
126 smp_mb__after_clear_bit();
127 if (waitqueue_active(wqh
))
132 * A queue has just entered congestion. Flag that in the queue's VM-visible
133 * state flags and increment the global gounter of congested queues.
135 static void set_queue_congested(request_queue_t
*q
, int rw
)
139 bit
= (rw
== WRITE
) ? BDI_write_congested
: BDI_read_congested
;
140 set_bit(bit
, &q
->backing_dev_info
.state
);
144 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
147 * Locates the passed device's request queue and returns the address of its
150 * Will return NULL if the request queue cannot be located.
152 struct backing_dev_info
*blk_get_backing_dev_info(struct block_device
*bdev
)
154 struct backing_dev_info
*ret
= NULL
;
155 request_queue_t
*q
= bdev_get_queue(bdev
);
158 ret
= &q
->backing_dev_info
;
162 EXPORT_SYMBOL(blk_get_backing_dev_info
);
164 void blk_queue_activity_fn(request_queue_t
*q
, activity_fn
*fn
, void *data
)
167 q
->activity_data
= data
;
170 EXPORT_SYMBOL(blk_queue_activity_fn
);
173 * blk_queue_prep_rq - set a prepare_request function for queue
175 * @pfn: prepare_request function
177 * It's possible for a queue to register a prepare_request callback which
178 * is invoked before the request is handed to the request_fn. The goal of
179 * the function is to prepare a request for I/O, it can be used to build a
180 * cdb from the request data for instance.
183 void blk_queue_prep_rq(request_queue_t
*q
, prep_rq_fn
*pfn
)
188 EXPORT_SYMBOL(blk_queue_prep_rq
);
191 * blk_queue_merge_bvec - set a merge_bvec function for queue
193 * @mbfn: merge_bvec_fn
195 * Usually queues have static limitations on the max sectors or segments that
196 * we can put in a request. Stacking drivers may have some settings that
197 * are dynamic, and thus we have to query the queue whether it is ok to
198 * add a new bio_vec to a bio at a given offset or not. If the block device
199 * has such limitations, it needs to register a merge_bvec_fn to control
200 * the size of bio's sent to it. Note that a block device *must* allow a
201 * single page to be added to an empty bio. The block device driver may want
202 * to use the bio_split() function to deal with these bio's. By default
203 * no merge_bvec_fn is defined for a queue, and only the fixed limits are
206 void blk_queue_merge_bvec(request_queue_t
*q
, merge_bvec_fn
*mbfn
)
208 q
->merge_bvec_fn
= mbfn
;
211 EXPORT_SYMBOL(blk_queue_merge_bvec
);
213 void blk_queue_softirq_done(request_queue_t
*q
, softirq_done_fn
*fn
)
215 q
->softirq_done_fn
= fn
;
218 EXPORT_SYMBOL(blk_queue_softirq_done
);
221 * blk_queue_make_request - define an alternate make_request function for a device
222 * @q: the request queue for the device to be affected
223 * @mfn: the alternate make_request function
226 * The normal way for &struct bios to be passed to a device
227 * driver is for them to be collected into requests on a request
228 * queue, and then to allow the device driver to select requests
229 * off that queue when it is ready. This works well for many block
230 * devices. However some block devices (typically virtual devices
231 * such as md or lvm) do not benefit from the processing on the
232 * request queue, and are served best by having the requests passed
233 * directly to them. This can be achieved by providing a function
234 * to blk_queue_make_request().
237 * The driver that does this *must* be able to deal appropriately
238 * with buffers in "highmemory". This can be accomplished by either calling
239 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
240 * blk_queue_bounce() to create a buffer in normal memory.
242 void blk_queue_make_request(request_queue_t
* q
, make_request_fn
* mfn
)
247 q
->nr_requests
= BLKDEV_MAX_RQ
;
248 blk_queue_max_phys_segments(q
, MAX_PHYS_SEGMENTS
);
249 blk_queue_max_hw_segments(q
, MAX_HW_SEGMENTS
);
250 q
->make_request_fn
= mfn
;
251 q
->backing_dev_info
.ra_pages
= (VM_MAX_READAHEAD
* 1024) / PAGE_CACHE_SIZE
;
252 q
->backing_dev_info
.state
= 0;
253 q
->backing_dev_info
.capabilities
= BDI_CAP_MAP_COPY
;
254 blk_queue_max_sectors(q
, SAFE_MAX_SECTORS
);
255 blk_queue_hardsect_size(q
, 512);
256 blk_queue_dma_alignment(q
, 511);
257 blk_queue_congestion_threshold(q
);
258 q
->nr_batching
= BLK_BATCH_REQ
;
260 q
->unplug_thresh
= 4; /* hmm */
261 q
->unplug_delay
= (3 * HZ
) / 1000; /* 3 milliseconds */
262 if (q
->unplug_delay
== 0)
265 INIT_WORK(&q
->unplug_work
, blk_unplug_work
, q
);
267 q
->unplug_timer
.function
= blk_unplug_timeout
;
268 q
->unplug_timer
.data
= (unsigned long)q
;
271 * by default assume old behaviour and bounce for any highmem page
273 blk_queue_bounce_limit(q
, BLK_BOUNCE_HIGH
);
275 blk_queue_activity_fn(q
, NULL
, NULL
);
278 EXPORT_SYMBOL(blk_queue_make_request
);
280 static inline void rq_init(request_queue_t
*q
, struct request
*rq
)
282 INIT_LIST_HEAD(&rq
->queuelist
);
283 INIT_LIST_HEAD(&rq
->donelist
);
286 rq
->rq_status
= RQ_ACTIVE
;
287 rq
->bio
= rq
->biotail
= NULL
;
296 rq
->nr_phys_segments
= 0;
299 rq
->end_io_data
= NULL
;
300 rq
->completion_data
= NULL
;
304 * blk_queue_ordered - does this queue support ordered writes
305 * @q: the request queue
306 * @ordered: one of QUEUE_ORDERED_*
307 * @prepare_flush_fn: rq setup helper for cache flush ordered writes
310 * For journalled file systems, doing ordered writes on a commit
311 * block instead of explicitly doing wait_on_buffer (which is bad
312 * for performance) can be a big win. Block drivers supporting this
313 * feature should call this function and indicate so.
316 int blk_queue_ordered(request_queue_t
*q
, unsigned ordered
,
317 prepare_flush_fn
*prepare_flush_fn
)
319 if (ordered
& (QUEUE_ORDERED_PREFLUSH
| QUEUE_ORDERED_POSTFLUSH
) &&
320 prepare_flush_fn
== NULL
) {
321 printk(KERN_ERR
"blk_queue_ordered: prepare_flush_fn required\n");
325 if (ordered
!= QUEUE_ORDERED_NONE
&&
326 ordered
!= QUEUE_ORDERED_DRAIN
&&
327 ordered
!= QUEUE_ORDERED_DRAIN_FLUSH
&&
328 ordered
!= QUEUE_ORDERED_DRAIN_FUA
&&
329 ordered
!= QUEUE_ORDERED_TAG
&&
330 ordered
!= QUEUE_ORDERED_TAG_FLUSH
&&
331 ordered
!= QUEUE_ORDERED_TAG_FUA
) {
332 printk(KERN_ERR
"blk_queue_ordered: bad value %d\n", ordered
);
336 q
->ordered
= ordered
;
337 q
->next_ordered
= ordered
;
338 q
->prepare_flush_fn
= prepare_flush_fn
;
343 EXPORT_SYMBOL(blk_queue_ordered
);
346 * blk_queue_issue_flush_fn - set function for issuing a flush
347 * @q: the request queue
348 * @iff: the function to be called issuing the flush
351 * If a driver supports issuing a flush command, the support is notified
352 * to the block layer by defining it through this call.
355 void blk_queue_issue_flush_fn(request_queue_t
*q
, issue_flush_fn
*iff
)
357 q
->issue_flush_fn
= iff
;
360 EXPORT_SYMBOL(blk_queue_issue_flush_fn
);
363 * Cache flushing for ordered writes handling
365 inline unsigned blk_ordered_cur_seq(request_queue_t
*q
)
369 return 1 << ffz(q
->ordseq
);
372 unsigned blk_ordered_req_seq(struct request
*rq
)
374 request_queue_t
*q
= rq
->q
;
376 BUG_ON(q
->ordseq
== 0);
378 if (rq
== &q
->pre_flush_rq
)
379 return QUEUE_ORDSEQ_PREFLUSH
;
380 if (rq
== &q
->bar_rq
)
381 return QUEUE_ORDSEQ_BAR
;
382 if (rq
== &q
->post_flush_rq
)
383 return QUEUE_ORDSEQ_POSTFLUSH
;
385 if ((rq
->flags
& REQ_ORDERED_COLOR
) ==
386 (q
->orig_bar_rq
->flags
& REQ_ORDERED_COLOR
))
387 return QUEUE_ORDSEQ_DRAIN
;
389 return QUEUE_ORDSEQ_DONE
;
392 void blk_ordered_complete_seq(request_queue_t
*q
, unsigned seq
, int error
)
397 if (error
&& !q
->orderr
)
400 BUG_ON(q
->ordseq
& seq
);
403 if (blk_ordered_cur_seq(q
) != QUEUE_ORDSEQ_DONE
)
407 * Okay, sequence complete.
410 uptodate
= q
->orderr
? q
->orderr
: 1;
414 end_that_request_first(rq
, uptodate
, rq
->hard_nr_sectors
);
415 end_that_request_last(rq
, uptodate
);
418 static void pre_flush_end_io(struct request
*rq
, int error
)
420 elv_completed_request(rq
->q
, rq
);
421 blk_ordered_complete_seq(rq
->q
, QUEUE_ORDSEQ_PREFLUSH
, error
);
424 static void bar_end_io(struct request
*rq
, int error
)
426 elv_completed_request(rq
->q
, rq
);
427 blk_ordered_complete_seq(rq
->q
, QUEUE_ORDSEQ_BAR
, error
);
430 static void post_flush_end_io(struct request
*rq
, int error
)
432 elv_completed_request(rq
->q
, rq
);
433 blk_ordered_complete_seq(rq
->q
, QUEUE_ORDSEQ_POSTFLUSH
, error
);
436 static void queue_flush(request_queue_t
*q
, unsigned which
)
439 rq_end_io_fn
*end_io
;
441 if (which
== QUEUE_ORDERED_PREFLUSH
) {
442 rq
= &q
->pre_flush_rq
;
443 end_io
= pre_flush_end_io
;
445 rq
= &q
->post_flush_rq
;
446 end_io
= post_flush_end_io
;
450 rq
->flags
= REQ_HARDBARRIER
;
451 rq
->elevator_private
= NULL
;
452 rq
->rq_disk
= q
->bar_rq
.rq_disk
;
455 q
->prepare_flush_fn(q
, rq
);
457 __elv_add_request(q
, rq
, ELEVATOR_INSERT_FRONT
, 0);
460 static inline struct request
*start_ordered(request_queue_t
*q
,
465 q
->ordered
= q
->next_ordered
;
466 q
->ordseq
|= QUEUE_ORDSEQ_STARTED
;
469 * Prep proxy barrier request.
471 blkdev_dequeue_request(rq
);
475 rq
->flags
= bio_data_dir(q
->orig_bar_rq
->bio
);
476 rq
->flags
|= q
->ordered
& QUEUE_ORDERED_FUA
? REQ_FUA
: 0;
477 rq
->elevator_private
= NULL
;
479 init_request_from_bio(rq
, q
->orig_bar_rq
->bio
);
480 rq
->end_io
= bar_end_io
;
483 * Queue ordered sequence. As we stack them at the head, we
484 * need to queue in reverse order. Note that we rely on that
485 * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs
486 * request gets inbetween ordered sequence.
488 if (q
->ordered
& QUEUE_ORDERED_POSTFLUSH
)
489 queue_flush(q
, QUEUE_ORDERED_POSTFLUSH
);
491 q
->ordseq
|= QUEUE_ORDSEQ_POSTFLUSH
;
493 __elv_add_request(q
, rq
, ELEVATOR_INSERT_FRONT
, 0);
495 if (q
->ordered
& QUEUE_ORDERED_PREFLUSH
) {
496 queue_flush(q
, QUEUE_ORDERED_PREFLUSH
);
497 rq
= &q
->pre_flush_rq
;
499 q
->ordseq
|= QUEUE_ORDSEQ_PREFLUSH
;
501 if ((q
->ordered
& QUEUE_ORDERED_TAG
) || q
->in_flight
== 0)
502 q
->ordseq
|= QUEUE_ORDSEQ_DRAIN
;
509 int blk_do_ordered(request_queue_t
*q
, struct request
**rqp
)
511 struct request
*rq
= *rqp
, *allowed_rq
;
512 int is_barrier
= blk_fs_request(rq
) && blk_barrier_rq(rq
);
518 if (q
->next_ordered
!= QUEUE_ORDERED_NONE
) {
519 *rqp
= start_ordered(q
, rq
);
523 * This can happen when the queue switches to
524 * ORDERED_NONE while this request is on it.
526 blkdev_dequeue_request(rq
);
527 end_that_request_first(rq
, -EOPNOTSUPP
,
528 rq
->hard_nr_sectors
);
529 end_that_request_last(rq
, -EOPNOTSUPP
);
535 if (q
->ordered
& QUEUE_ORDERED_TAG
) {
536 if (is_barrier
&& rq
!= &q
->bar_rq
)
541 switch (blk_ordered_cur_seq(q
)) {
542 case QUEUE_ORDSEQ_PREFLUSH
:
543 allowed_rq
= &q
->pre_flush_rq
;
545 case QUEUE_ORDSEQ_BAR
:
546 allowed_rq
= &q
->bar_rq
;
548 case QUEUE_ORDSEQ_POSTFLUSH
:
549 allowed_rq
= &q
->post_flush_rq
;
556 if (rq
!= allowed_rq
&&
557 (blk_fs_request(rq
) || rq
== &q
->pre_flush_rq
||
558 rq
== &q
->post_flush_rq
))
564 static int flush_dry_bio_endio(struct bio
*bio
, unsigned int bytes
, int error
)
566 request_queue_t
*q
= bio
->bi_private
;
567 struct bio_vec
*bvec
;
571 * This is dry run, restore bio_sector and size. We'll finish
572 * this request again with the original bi_end_io after an
573 * error occurs or post flush is complete.
582 bio_for_each_segment(bvec
, bio
, i
) {
583 bvec
->bv_len
+= bvec
->bv_offset
;
588 set_bit(BIO_UPTODATE
, &bio
->bi_flags
);
589 bio
->bi_size
= q
->bi_size
;
590 bio
->bi_sector
-= (q
->bi_size
>> 9);
596 static inline int ordered_bio_endio(struct request
*rq
, struct bio
*bio
,
597 unsigned int nbytes
, int error
)
599 request_queue_t
*q
= rq
->q
;
603 if (&q
->bar_rq
!= rq
)
607 * Okay, this is the barrier request in progress, dry finish it.
609 if (error
&& !q
->orderr
)
612 endio
= bio
->bi_end_io
;
613 private = bio
->bi_private
;
614 bio
->bi_end_io
= flush_dry_bio_endio
;
617 bio_endio(bio
, nbytes
, error
);
619 bio
->bi_end_io
= endio
;
620 bio
->bi_private
= private;
626 * blk_queue_bounce_limit - set bounce buffer limit for queue
627 * @q: the request queue for the device
628 * @dma_addr: bus address limit
631 * Different hardware can have different requirements as to what pages
632 * it can do I/O directly to. A low level driver can call
633 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
634 * buffers for doing I/O to pages residing above @page. By default
635 * the block layer sets this to the highest numbered "low" memory page.
637 void blk_queue_bounce_limit(request_queue_t
*q
, u64 dma_addr
)
639 unsigned long bounce_pfn
= dma_addr
>> PAGE_SHIFT
;
642 * set appropriate bounce gfp mask -- unfortunately we don't have a
643 * full 4GB zone, so we have to resort to low memory for any bounces.
644 * ISA has its own < 16MB zone.
646 if (bounce_pfn
< blk_max_low_pfn
) {
647 BUG_ON(dma_addr
< BLK_BOUNCE_ISA
);
648 init_emergency_isa_pool();
649 q
->bounce_gfp
= GFP_NOIO
| GFP_DMA
;
651 q
->bounce_gfp
= GFP_NOIO
;
653 q
->bounce_pfn
= bounce_pfn
;
656 EXPORT_SYMBOL(blk_queue_bounce_limit
);
659 * blk_queue_max_sectors - set max sectors for a request for this queue
660 * @q: the request queue for the device
661 * @max_sectors: max sectors in the usual 512b unit
664 * Enables a low level driver to set an upper limit on the size of
667 void blk_queue_max_sectors(request_queue_t
*q
, unsigned int max_sectors
)
669 if ((max_sectors
<< 9) < PAGE_CACHE_SIZE
) {
670 max_sectors
= 1 << (PAGE_CACHE_SHIFT
- 9);
671 printk("%s: set to minimum %d\n", __FUNCTION__
, max_sectors
);
674 if (BLK_DEF_MAX_SECTORS
> max_sectors
)
675 q
->max_hw_sectors
= q
->max_sectors
= max_sectors
;
677 q
->max_sectors
= BLK_DEF_MAX_SECTORS
;
678 q
->max_hw_sectors
= max_sectors
;
682 EXPORT_SYMBOL(blk_queue_max_sectors
);
685 * blk_queue_max_phys_segments - set max phys segments for a request for this queue
686 * @q: the request queue for the device
687 * @max_segments: max number of segments
690 * Enables a low level driver to set an upper limit on the number of
691 * physical data segments in a request. This would be the largest sized
692 * scatter list the driver could handle.
694 void blk_queue_max_phys_segments(request_queue_t
*q
, unsigned short max_segments
)
698 printk("%s: set to minimum %d\n", __FUNCTION__
, max_segments
);
701 q
->max_phys_segments
= max_segments
;
704 EXPORT_SYMBOL(blk_queue_max_phys_segments
);
707 * blk_queue_max_hw_segments - set max hw segments for a request for this queue
708 * @q: the request queue for the device
709 * @max_segments: max number of segments
712 * Enables a low level driver to set an upper limit on the number of
713 * hw data segments in a request. This would be the largest number of
714 * address/length pairs the host adapter can actually give as once
717 void blk_queue_max_hw_segments(request_queue_t
*q
, unsigned short max_segments
)
721 printk("%s: set to minimum %d\n", __FUNCTION__
, max_segments
);
724 q
->max_hw_segments
= max_segments
;
727 EXPORT_SYMBOL(blk_queue_max_hw_segments
);
730 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
731 * @q: the request queue for the device
732 * @max_size: max size of segment in bytes
735 * Enables a low level driver to set an upper limit on the size of a
738 void blk_queue_max_segment_size(request_queue_t
*q
, unsigned int max_size
)
740 if (max_size
< PAGE_CACHE_SIZE
) {
741 max_size
= PAGE_CACHE_SIZE
;
742 printk("%s: set to minimum %d\n", __FUNCTION__
, max_size
);
745 q
->max_segment_size
= max_size
;
748 EXPORT_SYMBOL(blk_queue_max_segment_size
);
751 * blk_queue_hardsect_size - set hardware sector size for the queue
752 * @q: the request queue for the device
753 * @size: the hardware sector size, in bytes
756 * This should typically be set to the lowest possible sector size
757 * that the hardware can operate on (possible without reverting to
758 * even internal read-modify-write operations). Usually the default
759 * of 512 covers most hardware.
761 void blk_queue_hardsect_size(request_queue_t
*q
, unsigned short size
)
763 q
->hardsect_size
= size
;
766 EXPORT_SYMBOL(blk_queue_hardsect_size
);
769 * Returns the minimum that is _not_ zero, unless both are zero.
771 #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
774 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
775 * @t: the stacking driver (top)
776 * @b: the underlying device (bottom)
778 void blk_queue_stack_limits(request_queue_t
*t
, request_queue_t
*b
)
780 /* zero is "infinity" */
781 t
->max_sectors
= min_not_zero(t
->max_sectors
,b
->max_sectors
);
782 t
->max_hw_sectors
= min_not_zero(t
->max_hw_sectors
,b
->max_hw_sectors
);
784 t
->max_phys_segments
= min(t
->max_phys_segments
,b
->max_phys_segments
);
785 t
->max_hw_segments
= min(t
->max_hw_segments
,b
->max_hw_segments
);
786 t
->max_segment_size
= min(t
->max_segment_size
,b
->max_segment_size
);
787 t
->hardsect_size
= max(t
->hardsect_size
,b
->hardsect_size
);
790 EXPORT_SYMBOL(blk_queue_stack_limits
);
793 * blk_queue_segment_boundary - set boundary rules for segment merging
794 * @q: the request queue for the device
795 * @mask: the memory boundary mask
797 void blk_queue_segment_boundary(request_queue_t
*q
, unsigned long mask
)
799 if (mask
< PAGE_CACHE_SIZE
- 1) {
800 mask
= PAGE_CACHE_SIZE
- 1;
801 printk("%s: set to minimum %lx\n", __FUNCTION__
, mask
);
804 q
->seg_boundary_mask
= mask
;
807 EXPORT_SYMBOL(blk_queue_segment_boundary
);
810 * blk_queue_dma_alignment - set dma length and memory alignment
811 * @q: the request queue for the device
812 * @mask: alignment mask
815 * set required memory and length aligment for direct dma transactions.
816 * this is used when buiding direct io requests for the queue.
819 void blk_queue_dma_alignment(request_queue_t
*q
, int mask
)
821 q
->dma_alignment
= mask
;
824 EXPORT_SYMBOL(blk_queue_dma_alignment
);
827 * blk_queue_find_tag - find a request by its tag and queue
828 * @q: The request queue for the device
829 * @tag: The tag of the request
832 * Should be used when a device returns a tag and you want to match
835 * no locks need be held.
837 struct request
*blk_queue_find_tag(request_queue_t
*q
, int tag
)
839 struct blk_queue_tag
*bqt
= q
->queue_tags
;
841 if (unlikely(bqt
== NULL
|| tag
>= bqt
->real_max_depth
))
844 return bqt
->tag_index
[tag
];
847 EXPORT_SYMBOL(blk_queue_find_tag
);
850 * __blk_queue_free_tags - release tag maintenance info
851 * @q: the request queue for the device
854 * blk_cleanup_queue() will take care of calling this function, if tagging
855 * has been used. So there's no need to call this directly.
857 static void __blk_queue_free_tags(request_queue_t
*q
)
859 struct blk_queue_tag
*bqt
= q
->queue_tags
;
864 if (atomic_dec_and_test(&bqt
->refcnt
)) {
866 BUG_ON(!list_empty(&bqt
->busy_list
));
868 kfree(bqt
->tag_index
);
869 bqt
->tag_index
= NULL
;
877 q
->queue_tags
= NULL
;
878 q
->queue_flags
&= ~(1 << QUEUE_FLAG_QUEUED
);
882 * blk_queue_free_tags - release tag maintenance info
883 * @q: the request queue for the device
886 * This is used to disabled tagged queuing to a device, yet leave
889 void blk_queue_free_tags(request_queue_t
*q
)
891 clear_bit(QUEUE_FLAG_QUEUED
, &q
->queue_flags
);
894 EXPORT_SYMBOL(blk_queue_free_tags
);
897 init_tag_map(request_queue_t
*q
, struct blk_queue_tag
*tags
, int depth
)
899 struct request
**tag_index
;
900 unsigned long *tag_map
;
903 if (depth
> q
->nr_requests
* 2) {
904 depth
= q
->nr_requests
* 2;
905 printk(KERN_ERR
"%s: adjusted depth to %d\n",
906 __FUNCTION__
, depth
);
909 tag_index
= kmalloc(depth
* sizeof(struct request
*), GFP_ATOMIC
);
913 nr_ulongs
= ALIGN(depth
, BITS_PER_LONG
) / BITS_PER_LONG
;
914 tag_map
= kmalloc(nr_ulongs
* sizeof(unsigned long), GFP_ATOMIC
);
918 memset(tag_index
, 0, depth
* sizeof(struct request
*));
919 memset(tag_map
, 0, nr_ulongs
* sizeof(unsigned long));
920 tags
->real_max_depth
= depth
;
921 tags
->max_depth
= depth
;
922 tags
->tag_index
= tag_index
;
923 tags
->tag_map
= tag_map
;
932 * blk_queue_init_tags - initialize the queue tag info
933 * @q: the request queue for the device
934 * @depth: the maximum queue depth supported
935 * @tags: the tag to use
937 int blk_queue_init_tags(request_queue_t
*q
, int depth
,
938 struct blk_queue_tag
*tags
)
942 BUG_ON(tags
&& q
->queue_tags
&& tags
!= q
->queue_tags
);
944 if (!tags
&& !q
->queue_tags
) {
945 tags
= kmalloc(sizeof(struct blk_queue_tag
), GFP_ATOMIC
);
949 if (init_tag_map(q
, tags
, depth
))
952 INIT_LIST_HEAD(&tags
->busy_list
);
954 atomic_set(&tags
->refcnt
, 1);
955 } else if (q
->queue_tags
) {
956 if ((rc
= blk_queue_resize_tags(q
, depth
)))
958 set_bit(QUEUE_FLAG_QUEUED
, &q
->queue_flags
);
961 atomic_inc(&tags
->refcnt
);
964 * assign it, all done
966 q
->queue_tags
= tags
;
967 q
->queue_flags
|= (1 << QUEUE_FLAG_QUEUED
);
974 EXPORT_SYMBOL(blk_queue_init_tags
);
977 * blk_queue_resize_tags - change the queueing depth
978 * @q: the request queue for the device
979 * @new_depth: the new max command queueing depth
982 * Must be called with the queue lock held.
984 int blk_queue_resize_tags(request_queue_t
*q
, int new_depth
)
986 struct blk_queue_tag
*bqt
= q
->queue_tags
;
987 struct request
**tag_index
;
988 unsigned long *tag_map
;
989 int max_depth
, nr_ulongs
;
995 * if we already have large enough real_max_depth. just
996 * adjust max_depth. *NOTE* as requests with tag value
997 * between new_depth and real_max_depth can be in-flight, tag
998 * map can not be shrunk blindly here.
1000 if (new_depth
<= bqt
->real_max_depth
) {
1001 bqt
->max_depth
= new_depth
;
1006 * save the old state info, so we can copy it back
1008 tag_index
= bqt
->tag_index
;
1009 tag_map
= bqt
->tag_map
;
1010 max_depth
= bqt
->real_max_depth
;
1012 if (init_tag_map(q
, bqt
, new_depth
))
1015 memcpy(bqt
->tag_index
, tag_index
, max_depth
* sizeof(struct request
*));
1016 nr_ulongs
= ALIGN(max_depth
, BITS_PER_LONG
) / BITS_PER_LONG
;
1017 memcpy(bqt
->tag_map
, tag_map
, nr_ulongs
* sizeof(unsigned long));
1024 EXPORT_SYMBOL(blk_queue_resize_tags
);
1027 * blk_queue_end_tag - end tag operations for a request
1028 * @q: the request queue for the device
1029 * @rq: the request that has completed
1032 * Typically called when end_that_request_first() returns 0, meaning
1033 * all transfers have been done for a request. It's important to call
1034 * this function before end_that_request_last(), as that will put the
1035 * request back on the free list thus corrupting the internal tag list.
1038 * queue lock must be held.
1040 void blk_queue_end_tag(request_queue_t
*q
, struct request
*rq
)
1042 struct blk_queue_tag
*bqt
= q
->queue_tags
;
1047 if (unlikely(tag
>= bqt
->real_max_depth
))
1049 * This can happen after tag depth has been reduced.
1050 * FIXME: how about a warning or info message here?
1054 if (unlikely(!__test_and_clear_bit(tag
, bqt
->tag_map
))) {
1055 printk(KERN_ERR
"%s: attempt to clear non-busy tag (%d)\n",
1060 list_del_init(&rq
->queuelist
);
1061 rq
->flags
&= ~REQ_QUEUED
;
1064 if (unlikely(bqt
->tag_index
[tag
] == NULL
))
1065 printk(KERN_ERR
"%s: tag %d is missing\n",
1068 bqt
->tag_index
[tag
] = NULL
;
1072 EXPORT_SYMBOL(blk_queue_end_tag
);
1075 * blk_queue_start_tag - find a free tag and assign it
1076 * @q: the request queue for the device
1077 * @rq: the block request that needs tagging
1080 * This can either be used as a stand-alone helper, or possibly be
1081 * assigned as the queue &prep_rq_fn (in which case &struct request
1082 * automagically gets a tag assigned). Note that this function
1083 * assumes that any type of request can be queued! if this is not
1084 * true for your device, you must check the request type before
1085 * calling this function. The request will also be removed from
1086 * the request queue, so it's the drivers responsibility to readd
1087 * it if it should need to be restarted for some reason.
1090 * queue lock must be held.
1092 int blk_queue_start_tag(request_queue_t
*q
, struct request
*rq
)
1094 struct blk_queue_tag
*bqt
= q
->queue_tags
;
1097 if (unlikely((rq
->flags
& REQ_QUEUED
))) {
1099 "%s: request %p for device [%s] already tagged %d",
1101 rq
->rq_disk
? rq
->rq_disk
->disk_name
: "?", rq
->tag
);
1105 tag
= find_first_zero_bit(bqt
->tag_map
, bqt
->max_depth
);
1106 if (tag
>= bqt
->max_depth
)
1109 __set_bit(tag
, bqt
->tag_map
);
1111 rq
->flags
|= REQ_QUEUED
;
1113 bqt
->tag_index
[tag
] = rq
;
1114 blkdev_dequeue_request(rq
);
1115 list_add(&rq
->queuelist
, &bqt
->busy_list
);
1120 EXPORT_SYMBOL(blk_queue_start_tag
);
1123 * blk_queue_invalidate_tags - invalidate all pending tags
1124 * @q: the request queue for the device
1127 * Hardware conditions may dictate a need to stop all pending requests.
1128 * In this case, we will safely clear the block side of the tag queue and
1129 * readd all requests to the request queue in the right order.
1132 * queue lock must be held.
1134 void blk_queue_invalidate_tags(request_queue_t
*q
)
1136 struct blk_queue_tag
*bqt
= q
->queue_tags
;
1137 struct list_head
*tmp
, *n
;
1140 list_for_each_safe(tmp
, n
, &bqt
->busy_list
) {
1141 rq
= list_entry_rq(tmp
);
1143 if (rq
->tag
== -1) {
1145 "%s: bad tag found on list\n", __FUNCTION__
);
1146 list_del_init(&rq
->queuelist
);
1147 rq
->flags
&= ~REQ_QUEUED
;
1149 blk_queue_end_tag(q
, rq
);
1151 rq
->flags
&= ~REQ_STARTED
;
1152 __elv_add_request(q
, rq
, ELEVATOR_INSERT_BACK
, 0);
1156 EXPORT_SYMBOL(blk_queue_invalidate_tags
);
1158 static const char * const rq_flags
[] = {
1179 "REQ_DRIVE_TASKFILE",
1184 "REQ_ORDERED_COLOR",
1187 void blk_dump_rq_flags(struct request
*rq
, char *msg
)
1191 printk("%s: dev %s: flags = ", msg
,
1192 rq
->rq_disk
? rq
->rq_disk
->disk_name
: "?");
1195 if (rq
->flags
& (1 << bit
))
1196 printk("%s ", rq_flags
[bit
]);
1198 } while (bit
< __REQ_NR_BITS
);
1200 printk("\nsector %llu, nr/cnr %lu/%u\n", (unsigned long long)rq
->sector
,
1202 rq
->current_nr_sectors
);
1203 printk("bio %p, biotail %p, buffer %p, data %p, len %u\n", rq
->bio
, rq
->biotail
, rq
->buffer
, rq
->data
, rq
->data_len
);
1205 if (rq
->flags
& (REQ_BLOCK_PC
| REQ_PC
)) {
1207 for (bit
= 0; bit
< sizeof(rq
->cmd
); bit
++)
1208 printk("%02x ", rq
->cmd
[bit
]);
1213 EXPORT_SYMBOL(blk_dump_rq_flags
);
1215 void blk_recount_segments(request_queue_t
*q
, struct bio
*bio
)
1217 struct bio_vec
*bv
, *bvprv
= NULL
;
1218 int i
, nr_phys_segs
, nr_hw_segs
, seg_size
, hw_seg_size
, cluster
;
1219 int high
, highprv
= 1;
1221 if (unlikely(!bio
->bi_io_vec
))
1224 cluster
= q
->queue_flags
& (1 << QUEUE_FLAG_CLUSTER
);
1225 hw_seg_size
= seg_size
= nr_phys_segs
= nr_hw_segs
= 0;
1226 bio_for_each_segment(bv
, bio
, i
) {
1228 * the trick here is making sure that a high page is never
1229 * considered part of another segment, since that might
1230 * change with the bounce page.
1232 high
= page_to_pfn(bv
->bv_page
) >= q
->bounce_pfn
;
1233 if (high
|| highprv
)
1234 goto new_hw_segment
;
1236 if (seg_size
+ bv
->bv_len
> q
->max_segment_size
)
1238 if (!BIOVEC_PHYS_MERGEABLE(bvprv
, bv
))
1240 if (!BIOVEC_SEG_BOUNDARY(q
, bvprv
, bv
))
1242 if (BIOVEC_VIRT_OVERSIZE(hw_seg_size
+ bv
->bv_len
))
1243 goto new_hw_segment
;
1245 seg_size
+= bv
->bv_len
;
1246 hw_seg_size
+= bv
->bv_len
;
1251 if (BIOVEC_VIRT_MERGEABLE(bvprv
, bv
) &&
1252 !BIOVEC_VIRT_OVERSIZE(hw_seg_size
+ bv
->bv_len
)) {
1253 hw_seg_size
+= bv
->bv_len
;
1256 if (hw_seg_size
> bio
->bi_hw_front_size
)
1257 bio
->bi_hw_front_size
= hw_seg_size
;
1258 hw_seg_size
= BIOVEC_VIRT_START_SIZE(bv
) + bv
->bv_len
;
1264 seg_size
= bv
->bv_len
;
1267 if (hw_seg_size
> bio
->bi_hw_back_size
)
1268 bio
->bi_hw_back_size
= hw_seg_size
;
1269 if (nr_hw_segs
== 1 && hw_seg_size
> bio
->bi_hw_front_size
)
1270 bio
->bi_hw_front_size
= hw_seg_size
;
1271 bio
->bi_phys_segments
= nr_phys_segs
;
1272 bio
->bi_hw_segments
= nr_hw_segs
;
1273 bio
->bi_flags
|= (1 << BIO_SEG_VALID
);
1277 static int blk_phys_contig_segment(request_queue_t
*q
, struct bio
*bio
,
1280 if (!(q
->queue_flags
& (1 << QUEUE_FLAG_CLUSTER
)))
1283 if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio
), __BVEC_START(nxt
)))
1285 if (bio
->bi_size
+ nxt
->bi_size
> q
->max_segment_size
)
1289 * bio and nxt are contigous in memory, check if the queue allows
1290 * these two to be merged into one
1292 if (BIO_SEG_BOUNDARY(q
, bio
, nxt
))
1298 static int blk_hw_contig_segment(request_queue_t
*q
, struct bio
*bio
,
1301 if (unlikely(!bio_flagged(bio
, BIO_SEG_VALID
)))
1302 blk_recount_segments(q
, bio
);
1303 if (unlikely(!bio_flagged(nxt
, BIO_SEG_VALID
)))
1304 blk_recount_segments(q
, nxt
);
1305 if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio
), __BVEC_START(nxt
)) ||
1306 BIOVEC_VIRT_OVERSIZE(bio
->bi_hw_front_size
+ bio
->bi_hw_back_size
))
1308 if (bio
->bi_size
+ nxt
->bi_size
> q
->max_segment_size
)
1315 * map a request to scatterlist, return number of sg entries setup. Caller
1316 * must make sure sg can hold rq->nr_phys_segments entries
1318 int blk_rq_map_sg(request_queue_t
*q
, struct request
*rq
, struct scatterlist
*sg
)
1320 struct bio_vec
*bvec
, *bvprv
;
1322 int nsegs
, i
, cluster
;
1325 cluster
= q
->queue_flags
& (1 << QUEUE_FLAG_CLUSTER
);
1328 * for each bio in rq
1331 rq_for_each_bio(bio
, rq
) {
1333 * for each segment in bio
1335 bio_for_each_segment(bvec
, bio
, i
) {
1336 int nbytes
= bvec
->bv_len
;
1338 if (bvprv
&& cluster
) {
1339 if (sg
[nsegs
- 1].length
+ nbytes
> q
->max_segment_size
)
1342 if (!BIOVEC_PHYS_MERGEABLE(bvprv
, bvec
))
1344 if (!BIOVEC_SEG_BOUNDARY(q
, bvprv
, bvec
))
1347 sg
[nsegs
- 1].length
+= nbytes
;
1350 memset(&sg
[nsegs
],0,sizeof(struct scatterlist
));
1351 sg
[nsegs
].page
= bvec
->bv_page
;
1352 sg
[nsegs
].length
= nbytes
;
1353 sg
[nsegs
].offset
= bvec
->bv_offset
;
1358 } /* segments in bio */
1364 EXPORT_SYMBOL(blk_rq_map_sg
);
1367 * the standard queue merge functions, can be overridden with device
1368 * specific ones if so desired
1371 static inline int ll_new_mergeable(request_queue_t
*q
,
1372 struct request
*req
,
1375 int nr_phys_segs
= bio_phys_segments(q
, bio
);
1377 if (req
->nr_phys_segments
+ nr_phys_segs
> q
->max_phys_segments
) {
1378 req
->flags
|= REQ_NOMERGE
;
1379 if (req
== q
->last_merge
)
1380 q
->last_merge
= NULL
;
1385 * A hw segment is just getting larger, bump just the phys
1388 req
->nr_phys_segments
+= nr_phys_segs
;
1392 static inline int ll_new_hw_segment(request_queue_t
*q
,
1393 struct request
*req
,
1396 int nr_hw_segs
= bio_hw_segments(q
, bio
);
1397 int nr_phys_segs
= bio_phys_segments(q
, bio
);
1399 if (req
->nr_hw_segments
+ nr_hw_segs
> q
->max_hw_segments
1400 || req
->nr_phys_segments
+ nr_phys_segs
> q
->max_phys_segments
) {
1401 req
->flags
|= REQ_NOMERGE
;
1402 if (req
== q
->last_merge
)
1403 q
->last_merge
= NULL
;
1408 * This will form the start of a new hw segment. Bump both
1411 req
->nr_hw_segments
+= nr_hw_segs
;
1412 req
->nr_phys_segments
+= nr_phys_segs
;
1416 static int ll_back_merge_fn(request_queue_t
*q
, struct request
*req
,
1419 unsigned short max_sectors
;
1422 if (unlikely(blk_pc_request(req
)))
1423 max_sectors
= q
->max_hw_sectors
;
1425 max_sectors
= q
->max_sectors
;
1427 if (req
->nr_sectors
+ bio_sectors(bio
) > max_sectors
) {
1428 req
->flags
|= REQ_NOMERGE
;
1429 if (req
== q
->last_merge
)
1430 q
->last_merge
= NULL
;
1433 if (unlikely(!bio_flagged(req
->biotail
, BIO_SEG_VALID
)))
1434 blk_recount_segments(q
, req
->biotail
);
1435 if (unlikely(!bio_flagged(bio
, BIO_SEG_VALID
)))
1436 blk_recount_segments(q
, bio
);
1437 len
= req
->biotail
->bi_hw_back_size
+ bio
->bi_hw_front_size
;
1438 if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req
->biotail
), __BVEC_START(bio
)) &&
1439 !BIOVEC_VIRT_OVERSIZE(len
)) {
1440 int mergeable
= ll_new_mergeable(q
, req
, bio
);
1443 if (req
->nr_hw_segments
== 1)
1444 req
->bio
->bi_hw_front_size
= len
;
1445 if (bio
->bi_hw_segments
== 1)
1446 bio
->bi_hw_back_size
= len
;
1451 return ll_new_hw_segment(q
, req
, bio
);
1454 static int ll_front_merge_fn(request_queue_t
*q
, struct request
*req
,
1457 unsigned short max_sectors
;
1460 if (unlikely(blk_pc_request(req
)))
1461 max_sectors
= q
->max_hw_sectors
;
1463 max_sectors
= q
->max_sectors
;
1466 if (req
->nr_sectors
+ bio_sectors(bio
) > max_sectors
) {
1467 req
->flags
|= REQ_NOMERGE
;
1468 if (req
== q
->last_merge
)
1469 q
->last_merge
= NULL
;
1472 len
= bio
->bi_hw_back_size
+ req
->bio
->bi_hw_front_size
;
1473 if (unlikely(!bio_flagged(bio
, BIO_SEG_VALID
)))
1474 blk_recount_segments(q
, bio
);
1475 if (unlikely(!bio_flagged(req
->bio
, BIO_SEG_VALID
)))
1476 blk_recount_segments(q
, req
->bio
);
1477 if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio
), __BVEC_START(req
->bio
)) &&
1478 !BIOVEC_VIRT_OVERSIZE(len
)) {
1479 int mergeable
= ll_new_mergeable(q
, req
, bio
);
1482 if (bio
->bi_hw_segments
== 1)
1483 bio
->bi_hw_front_size
= len
;
1484 if (req
->nr_hw_segments
== 1)
1485 req
->biotail
->bi_hw_back_size
= len
;
1490 return ll_new_hw_segment(q
, req
, bio
);
1493 static int ll_merge_requests_fn(request_queue_t
*q
, struct request
*req
,
1494 struct request
*next
)
1496 int total_phys_segments
;
1497 int total_hw_segments
;
1500 * First check if the either of the requests are re-queued
1501 * requests. Can't merge them if they are.
1503 if (req
->special
|| next
->special
)
1507 * Will it become too large?
1509 if ((req
->nr_sectors
+ next
->nr_sectors
) > q
->max_sectors
)
1512 total_phys_segments
= req
->nr_phys_segments
+ next
->nr_phys_segments
;
1513 if (blk_phys_contig_segment(q
, req
->biotail
, next
->bio
))
1514 total_phys_segments
--;
1516 if (total_phys_segments
> q
->max_phys_segments
)
1519 total_hw_segments
= req
->nr_hw_segments
+ next
->nr_hw_segments
;
1520 if (blk_hw_contig_segment(q
, req
->biotail
, next
->bio
)) {
1521 int len
= req
->biotail
->bi_hw_back_size
+ next
->bio
->bi_hw_front_size
;
1523 * propagate the combined length to the end of the requests
1525 if (req
->nr_hw_segments
== 1)
1526 req
->bio
->bi_hw_front_size
= len
;
1527 if (next
->nr_hw_segments
== 1)
1528 next
->biotail
->bi_hw_back_size
= len
;
1529 total_hw_segments
--;
1532 if (total_hw_segments
> q
->max_hw_segments
)
1535 /* Merge is OK... */
1536 req
->nr_phys_segments
= total_phys_segments
;
1537 req
->nr_hw_segments
= total_hw_segments
;
1542 * "plug" the device if there are no outstanding requests: this will
1543 * force the transfer to start only after we have put all the requests
1546 * This is called with interrupts off and no requests on the queue and
1547 * with the queue lock held.
1549 void blk_plug_device(request_queue_t
*q
)
1551 WARN_ON(!irqs_disabled());
1554 * don't plug a stopped queue, it must be paired with blk_start_queue()
1555 * which will restart the queueing
1557 if (test_bit(QUEUE_FLAG_STOPPED
, &q
->queue_flags
))
1560 if (!test_and_set_bit(QUEUE_FLAG_PLUGGED
, &q
->queue_flags
))
1561 mod_timer(&q
->unplug_timer
, jiffies
+ q
->unplug_delay
);
1564 EXPORT_SYMBOL(blk_plug_device
);
1567 * remove the queue from the plugged list, if present. called with
1568 * queue lock held and interrupts disabled.
1570 int blk_remove_plug(request_queue_t
*q
)
1572 WARN_ON(!irqs_disabled());
1574 if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED
, &q
->queue_flags
))
1577 del_timer(&q
->unplug_timer
);
1581 EXPORT_SYMBOL(blk_remove_plug
);
1584 * remove the plug and let it rip..
1586 void __generic_unplug_device(request_queue_t
*q
)
1588 if (unlikely(test_bit(QUEUE_FLAG_STOPPED
, &q
->queue_flags
)))
1591 if (!blk_remove_plug(q
))
1596 EXPORT_SYMBOL(__generic_unplug_device
);
1599 * generic_unplug_device - fire a request queue
1600 * @q: The &request_queue_t in question
1603 * Linux uses plugging to build bigger requests queues before letting
1604 * the device have at them. If a queue is plugged, the I/O scheduler
1605 * is still adding and merging requests on the queue. Once the queue
1606 * gets unplugged, the request_fn defined for the queue is invoked and
1607 * transfers started.
1609 void generic_unplug_device(request_queue_t
*q
)
1611 spin_lock_irq(q
->queue_lock
);
1612 __generic_unplug_device(q
);
1613 spin_unlock_irq(q
->queue_lock
);
1615 EXPORT_SYMBOL(generic_unplug_device
);
1617 static void blk_backing_dev_unplug(struct backing_dev_info
*bdi
,
1620 request_queue_t
*q
= bdi
->unplug_io_data
;
1623 * devices don't necessarily have an ->unplug_fn defined
1629 static void blk_unplug_work(void *data
)
1631 request_queue_t
*q
= data
;
1636 static void blk_unplug_timeout(unsigned long data
)
1638 request_queue_t
*q
= (request_queue_t
*)data
;
1640 kblockd_schedule_work(&q
->unplug_work
);
1644 * blk_start_queue - restart a previously stopped queue
1645 * @q: The &request_queue_t in question
1648 * blk_start_queue() will clear the stop flag on the queue, and call
1649 * the request_fn for the queue if it was in a stopped state when
1650 * entered. Also see blk_stop_queue(). Queue lock must be held.
1652 void blk_start_queue(request_queue_t
*q
)
1654 clear_bit(QUEUE_FLAG_STOPPED
, &q
->queue_flags
);
1657 * one level of recursion is ok and is much faster than kicking
1658 * the unplug handling
1660 if (!test_and_set_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
)) {
1662 clear_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
);
1665 kblockd_schedule_work(&q
->unplug_work
);
1669 EXPORT_SYMBOL(blk_start_queue
);
1672 * blk_stop_queue - stop a queue
1673 * @q: The &request_queue_t in question
1676 * The Linux block layer assumes that a block driver will consume all
1677 * entries on the request queue when the request_fn strategy is called.
1678 * Often this will not happen, because of hardware limitations (queue
1679 * depth settings). If a device driver gets a 'queue full' response,
1680 * or if it simply chooses not to queue more I/O at one point, it can
1681 * call this function to prevent the request_fn from being called until
1682 * the driver has signalled it's ready to go again. This happens by calling
1683 * blk_start_queue() to restart queue operations. Queue lock must be held.
1685 void blk_stop_queue(request_queue_t
*q
)
1688 set_bit(QUEUE_FLAG_STOPPED
, &q
->queue_flags
);
1690 EXPORT_SYMBOL(blk_stop_queue
);
1693 * blk_sync_queue - cancel any pending callbacks on a queue
1697 * The block layer may perform asynchronous callback activity
1698 * on a queue, such as calling the unplug function after a timeout.
1699 * A block device may call blk_sync_queue to ensure that any
1700 * such activity is cancelled, thus allowing it to release resources
1701 * the the callbacks might use. The caller must already have made sure
1702 * that its ->make_request_fn will not re-add plugging prior to calling
1706 void blk_sync_queue(struct request_queue
*q
)
1708 del_timer_sync(&q
->unplug_timer
);
1711 EXPORT_SYMBOL(blk_sync_queue
);
1714 * blk_run_queue - run a single device queue
1715 * @q: The queue to run
1717 void blk_run_queue(struct request_queue
*q
)
1719 unsigned long flags
;
1721 spin_lock_irqsave(q
->queue_lock
, flags
);
1723 if (!elv_queue_empty(q
))
1725 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1727 EXPORT_SYMBOL(blk_run_queue
);
1730 * blk_cleanup_queue: - release a &request_queue_t when it is no longer needed
1731 * @q: the request queue to be released
1734 * blk_cleanup_queue is the pair to blk_init_queue() or
1735 * blk_queue_make_request(). It should be called when a request queue is
1736 * being released; typically when a block device is being de-registered.
1737 * Currently, its primary task it to free all the &struct request
1738 * structures that were allocated to the queue and the queue itself.
1741 * Hopefully the low level driver will have finished any
1742 * outstanding requests first...
1744 void blk_cleanup_queue(request_queue_t
* q
)
1746 struct request_list
*rl
= &q
->rq
;
1748 if (!atomic_dec_and_test(&q
->refcnt
))
1752 elevator_exit(q
->elevator
);
1757 mempool_destroy(rl
->rq_pool
);
1760 __blk_queue_free_tags(q
);
1762 kmem_cache_free(requestq_cachep
, q
);
1765 EXPORT_SYMBOL(blk_cleanup_queue
);
1767 static int blk_init_free_list(request_queue_t
*q
)
1769 struct request_list
*rl
= &q
->rq
;
1771 rl
->count
[READ
] = rl
->count
[WRITE
] = 0;
1772 rl
->starved
[READ
] = rl
->starved
[WRITE
] = 0;
1774 init_waitqueue_head(&rl
->wait
[READ
]);
1775 init_waitqueue_head(&rl
->wait
[WRITE
]);
1777 rl
->rq_pool
= mempool_create_node(BLKDEV_MIN_RQ
, mempool_alloc_slab
,
1778 mempool_free_slab
, request_cachep
, q
->node
);
1786 request_queue_t
*blk_alloc_queue(gfp_t gfp_mask
)
1788 return blk_alloc_queue_node(gfp_mask
, -1);
1790 EXPORT_SYMBOL(blk_alloc_queue
);
1792 request_queue_t
*blk_alloc_queue_node(gfp_t gfp_mask
, int node_id
)
1796 q
= kmem_cache_alloc_node(requestq_cachep
, gfp_mask
, node_id
);
1800 memset(q
, 0, sizeof(*q
));
1801 init_timer(&q
->unplug_timer
);
1802 atomic_set(&q
->refcnt
, 1);
1804 q
->backing_dev_info
.unplug_io_fn
= blk_backing_dev_unplug
;
1805 q
->backing_dev_info
.unplug_io_data
= q
;
1809 EXPORT_SYMBOL(blk_alloc_queue_node
);
1812 * blk_init_queue - prepare a request queue for use with a block device
1813 * @rfn: The function to be called to process requests that have been
1814 * placed on the queue.
1815 * @lock: Request queue spin lock
1818 * If a block device wishes to use the standard request handling procedures,
1819 * which sorts requests and coalesces adjacent requests, then it must
1820 * call blk_init_queue(). The function @rfn will be called when there
1821 * are requests on the queue that need to be processed. If the device
1822 * supports plugging, then @rfn may not be called immediately when requests
1823 * are available on the queue, but may be called at some time later instead.
1824 * Plugged queues are generally unplugged when a buffer belonging to one
1825 * of the requests on the queue is needed, or due to memory pressure.
1827 * @rfn is not required, or even expected, to remove all requests off the
1828 * queue, but only as many as it can handle at a time. If it does leave
1829 * requests on the queue, it is responsible for arranging that the requests
1830 * get dealt with eventually.
1832 * The queue spin lock must be held while manipulating the requests on the
1835 * Function returns a pointer to the initialized request queue, or NULL if
1836 * it didn't succeed.
1839 * blk_init_queue() must be paired with a blk_cleanup_queue() call
1840 * when the block device is deactivated (such as at module unload).
1843 request_queue_t
*blk_init_queue(request_fn_proc
*rfn
, spinlock_t
*lock
)
1845 return blk_init_queue_node(rfn
, lock
, -1);
1847 EXPORT_SYMBOL(blk_init_queue
);
1850 blk_init_queue_node(request_fn_proc
*rfn
, spinlock_t
*lock
, int node_id
)
1852 request_queue_t
*q
= blk_alloc_queue_node(GFP_KERNEL
, node_id
);
1858 if (blk_init_free_list(q
))
1862 * if caller didn't supply a lock, they get per-queue locking with
1866 spin_lock_init(&q
->__queue_lock
);
1867 lock
= &q
->__queue_lock
;
1870 q
->request_fn
= rfn
;
1871 q
->back_merge_fn
= ll_back_merge_fn
;
1872 q
->front_merge_fn
= ll_front_merge_fn
;
1873 q
->merge_requests_fn
= ll_merge_requests_fn
;
1874 q
->prep_rq_fn
= NULL
;
1875 q
->unplug_fn
= generic_unplug_device
;
1876 q
->queue_flags
= (1 << QUEUE_FLAG_CLUSTER
);
1877 q
->queue_lock
= lock
;
1879 blk_queue_segment_boundary(q
, 0xffffffff);
1881 blk_queue_make_request(q
, __make_request
);
1882 blk_queue_max_segment_size(q
, MAX_SEGMENT_SIZE
);
1884 blk_queue_max_hw_segments(q
, MAX_HW_SEGMENTS
);
1885 blk_queue_max_phys_segments(q
, MAX_PHYS_SEGMENTS
);
1890 if (!elevator_init(q
, NULL
)) {
1891 blk_queue_congestion_threshold(q
);
1895 blk_cleanup_queue(q
);
1897 kmem_cache_free(requestq_cachep
, q
);
1900 EXPORT_SYMBOL(blk_init_queue_node
);
1902 int blk_get_queue(request_queue_t
*q
)
1904 if (likely(!test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
))) {
1905 atomic_inc(&q
->refcnt
);
1912 EXPORT_SYMBOL(blk_get_queue
);
1914 static inline void blk_free_request(request_queue_t
*q
, struct request
*rq
)
1916 if (rq
->flags
& REQ_ELVPRIV
)
1917 elv_put_request(q
, rq
);
1918 mempool_free(rq
, q
->rq
.rq_pool
);
1921 static inline struct request
*
1922 blk_alloc_request(request_queue_t
*q
, int rw
, struct bio
*bio
,
1923 int priv
, gfp_t gfp_mask
)
1925 struct request
*rq
= mempool_alloc(q
->rq
.rq_pool
, gfp_mask
);
1931 * first three bits are identical in rq->flags and bio->bi_rw,
1932 * see bio.h and blkdev.h
1937 if (unlikely(elv_set_request(q
, rq
, bio
, gfp_mask
))) {
1938 mempool_free(rq
, q
->rq
.rq_pool
);
1941 rq
->flags
|= REQ_ELVPRIV
;
1948 * ioc_batching returns true if the ioc is a valid batching request and
1949 * should be given priority access to a request.
1951 static inline int ioc_batching(request_queue_t
*q
, struct io_context
*ioc
)
1957 * Make sure the process is able to allocate at least 1 request
1958 * even if the batch times out, otherwise we could theoretically
1961 return ioc
->nr_batch_requests
== q
->nr_batching
||
1962 (ioc
->nr_batch_requests
> 0
1963 && time_before(jiffies
, ioc
->last_waited
+ BLK_BATCH_TIME
));
1967 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
1968 * will cause the process to be a "batcher" on all queues in the system. This
1969 * is the behaviour we want though - once it gets a wakeup it should be given
1972 static void ioc_set_batching(request_queue_t
*q
, struct io_context
*ioc
)
1974 if (!ioc
|| ioc_batching(q
, ioc
))
1977 ioc
->nr_batch_requests
= q
->nr_batching
;
1978 ioc
->last_waited
= jiffies
;
1981 static void __freed_request(request_queue_t
*q
, int rw
)
1983 struct request_list
*rl
= &q
->rq
;
1985 if (rl
->count
[rw
] < queue_congestion_off_threshold(q
))
1986 clear_queue_congested(q
, rw
);
1988 if (rl
->count
[rw
] + 1 <= q
->nr_requests
) {
1989 if (waitqueue_active(&rl
->wait
[rw
]))
1990 wake_up(&rl
->wait
[rw
]);
1992 blk_clear_queue_full(q
, rw
);
1997 * A request has just been released. Account for it, update the full and
1998 * congestion status, wake up any waiters. Called under q->queue_lock.
2000 static void freed_request(request_queue_t
*q
, int rw
, int priv
)
2002 struct request_list
*rl
= &q
->rq
;
2008 __freed_request(q
, rw
);
2010 if (unlikely(rl
->starved
[rw
^ 1]))
2011 __freed_request(q
, rw
^ 1);
2014 #define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist)
2016 * Get a free request, queue_lock must be held.
2017 * Returns NULL on failure, with queue_lock held.
2018 * Returns !NULL on success, with queue_lock *not held*.
2020 static struct request
*get_request(request_queue_t
*q
, int rw
, struct bio
*bio
,
2023 struct request
*rq
= NULL
;
2024 struct request_list
*rl
= &q
->rq
;
2025 struct io_context
*ioc
= NULL
;
2026 int may_queue
, priv
;
2028 may_queue
= elv_may_queue(q
, rw
, bio
);
2029 if (may_queue
== ELV_MQUEUE_NO
)
2032 if (rl
->count
[rw
]+1 >= queue_congestion_on_threshold(q
)) {
2033 if (rl
->count
[rw
]+1 >= q
->nr_requests
) {
2034 ioc
= current_io_context(GFP_ATOMIC
);
2036 * The queue will fill after this allocation, so set
2037 * it as full, and mark this process as "batching".
2038 * This process will be allowed to complete a batch of
2039 * requests, others will be blocked.
2041 if (!blk_queue_full(q
, rw
)) {
2042 ioc_set_batching(q
, ioc
);
2043 blk_set_queue_full(q
, rw
);
2045 if (may_queue
!= ELV_MQUEUE_MUST
2046 && !ioc_batching(q
, ioc
)) {
2048 * The queue is full and the allocating
2049 * process is not a "batcher", and not
2050 * exempted by the IO scheduler
2056 set_queue_congested(q
, rw
);
2060 * Only allow batching queuers to allocate up to 50% over the defined
2061 * limit of requests, otherwise we could have thousands of requests
2062 * allocated with any setting of ->nr_requests
2064 if (rl
->count
[rw
] >= (3 * q
->nr_requests
/ 2))
2068 rl
->starved
[rw
] = 0;
2070 priv
= !test_bit(QUEUE_FLAG_ELVSWITCH
, &q
->queue_flags
);
2074 spin_unlock_irq(q
->queue_lock
);
2076 rq
= blk_alloc_request(q
, rw
, bio
, priv
, gfp_mask
);
2077 if (unlikely(!rq
)) {
2079 * Allocation failed presumably due to memory. Undo anything
2080 * we might have messed up.
2082 * Allocating task should really be put onto the front of the
2083 * wait queue, but this is pretty rare.
2085 spin_lock_irq(q
->queue_lock
);
2086 freed_request(q
, rw
, priv
);
2089 * in the very unlikely event that allocation failed and no
2090 * requests for this direction was pending, mark us starved
2091 * so that freeing of a request in the other direction will
2092 * notice us. another possible fix would be to split the
2093 * rq mempool into READ and WRITE
2096 if (unlikely(rl
->count
[rw
] == 0))
2097 rl
->starved
[rw
] = 1;
2103 * ioc may be NULL here, and ioc_batching will be false. That's
2104 * OK, if the queue is under the request limit then requests need
2105 * not count toward the nr_batch_requests limit. There will always
2106 * be some limit enforced by BLK_BATCH_TIME.
2108 if (ioc_batching(q
, ioc
))
2109 ioc
->nr_batch_requests
--;
2118 * No available requests for this queue, unplug the device and wait for some
2119 * requests to become available.
2121 * Called with q->queue_lock held, and returns with it unlocked.
2123 static struct request
*get_request_wait(request_queue_t
*q
, int rw
,
2128 rq
= get_request(q
, rw
, bio
, GFP_NOIO
);
2131 struct request_list
*rl
= &q
->rq
;
2133 prepare_to_wait_exclusive(&rl
->wait
[rw
], &wait
,
2134 TASK_UNINTERRUPTIBLE
);
2136 rq
= get_request(q
, rw
, bio
, GFP_NOIO
);
2139 struct io_context
*ioc
;
2141 __generic_unplug_device(q
);
2142 spin_unlock_irq(q
->queue_lock
);
2146 * After sleeping, we become a "batching" process and
2147 * will be able to allocate at least one request, and
2148 * up to a big batch of them for a small period time.
2149 * See ioc_batching, ioc_set_batching
2151 ioc
= current_io_context(GFP_NOIO
);
2152 ioc_set_batching(q
, ioc
);
2154 spin_lock_irq(q
->queue_lock
);
2156 finish_wait(&rl
->wait
[rw
], &wait
);
2162 struct request
*blk_get_request(request_queue_t
*q
, int rw
, gfp_t gfp_mask
)
2166 BUG_ON(rw
!= READ
&& rw
!= WRITE
);
2168 spin_lock_irq(q
->queue_lock
);
2169 if (gfp_mask
& __GFP_WAIT
) {
2170 rq
= get_request_wait(q
, rw
, NULL
);
2172 rq
= get_request(q
, rw
, NULL
, gfp_mask
);
2174 spin_unlock_irq(q
->queue_lock
);
2176 /* q->queue_lock is unlocked at this point */
2180 EXPORT_SYMBOL(blk_get_request
);
2183 * blk_requeue_request - put a request back on queue
2184 * @q: request queue where request should be inserted
2185 * @rq: request to be inserted
2188 * Drivers often keep queueing requests until the hardware cannot accept
2189 * more, when that condition happens we need to put the request back
2190 * on the queue. Must be called with queue lock held.
2192 void blk_requeue_request(request_queue_t
*q
, struct request
*rq
)
2194 if (blk_rq_tagged(rq
))
2195 blk_queue_end_tag(q
, rq
);
2197 elv_requeue_request(q
, rq
);
2200 EXPORT_SYMBOL(blk_requeue_request
);
2203 * blk_insert_request - insert a special request in to a request queue
2204 * @q: request queue where request should be inserted
2205 * @rq: request to be inserted
2206 * @at_head: insert request at head or tail of queue
2207 * @data: private data
2210 * Many block devices need to execute commands asynchronously, so they don't
2211 * block the whole kernel from preemption during request execution. This is
2212 * accomplished normally by inserting aritficial requests tagged as
2213 * REQ_SPECIAL in to the corresponding request queue, and letting them be
2214 * scheduled for actual execution by the request queue.
2216 * We have the option of inserting the head or the tail of the queue.
2217 * Typically we use the tail for new ioctls and so forth. We use the head
2218 * of the queue for things like a QUEUE_FULL message from a device, or a
2219 * host that is unable to accept a particular command.
2221 void blk_insert_request(request_queue_t
*q
, struct request
*rq
,
2222 int at_head
, void *data
)
2224 int where
= at_head
? ELEVATOR_INSERT_FRONT
: ELEVATOR_INSERT_BACK
;
2225 unsigned long flags
;
2228 * tell I/O scheduler that this isn't a regular read/write (ie it
2229 * must not attempt merges on this) and that it acts as a soft
2232 rq
->flags
|= REQ_SPECIAL
| REQ_SOFTBARRIER
;
2236 spin_lock_irqsave(q
->queue_lock
, flags
);
2239 * If command is tagged, release the tag
2241 if (blk_rq_tagged(rq
))
2242 blk_queue_end_tag(q
, rq
);
2244 drive_stat_acct(rq
, rq
->nr_sectors
, 1);
2245 __elv_add_request(q
, rq
, where
, 0);
2247 if (blk_queue_plugged(q
))
2248 __generic_unplug_device(q
);
2251 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2254 EXPORT_SYMBOL(blk_insert_request
);
2257 * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
2258 * @q: request queue where request should be inserted
2259 * @rq: request structure to fill
2260 * @ubuf: the user buffer
2261 * @len: length of user data
2264 * Data will be mapped directly for zero copy io, if possible. Otherwise
2265 * a kernel bounce buffer is used.
2267 * A matching blk_rq_unmap_user() must be issued at the end of io, while
2268 * still in process context.
2270 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
2271 * before being submitted to the device, as pages mapped may be out of
2272 * reach. It's the callers responsibility to make sure this happens. The
2273 * original bio must be passed back in to blk_rq_unmap_user() for proper
2276 int blk_rq_map_user(request_queue_t
*q
, struct request
*rq
, void __user
*ubuf
,
2279 unsigned long uaddr
;
2283 if (len
> (q
->max_hw_sectors
<< 9))
2288 reading
= rq_data_dir(rq
) == READ
;
2291 * if alignment requirement is satisfied, map in user pages for
2292 * direct dma. else, set up kernel bounce buffers
2294 uaddr
= (unsigned long) ubuf
;
2295 if (!(uaddr
& queue_dma_alignment(q
)) && !(len
& queue_dma_alignment(q
)))
2296 bio
= bio_map_user(q
, NULL
, uaddr
, len
, reading
);
2298 bio
= bio_copy_user(q
, uaddr
, len
, reading
);
2301 rq
->bio
= rq
->biotail
= bio
;
2302 blk_rq_bio_prep(q
, rq
, bio
);
2304 rq
->buffer
= rq
->data
= NULL
;
2310 * bio is the err-ptr
2312 return PTR_ERR(bio
);
2315 EXPORT_SYMBOL(blk_rq_map_user
);
2318 * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage
2319 * @q: request queue where request should be inserted
2320 * @rq: request to map data to
2321 * @iov: pointer to the iovec
2322 * @iov_count: number of elements in the iovec
2325 * Data will be mapped directly for zero copy io, if possible. Otherwise
2326 * a kernel bounce buffer is used.
2328 * A matching blk_rq_unmap_user() must be issued at the end of io, while
2329 * still in process context.
2331 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
2332 * before being submitted to the device, as pages mapped may be out of
2333 * reach. It's the callers responsibility to make sure this happens. The
2334 * original bio must be passed back in to blk_rq_unmap_user() for proper
2337 int blk_rq_map_user_iov(request_queue_t
*q
, struct request
*rq
,
2338 struct sg_iovec
*iov
, int iov_count
)
2342 if (!iov
|| iov_count
<= 0)
2345 /* we don't allow misaligned data like bio_map_user() does. If the
2346 * user is using sg, they're expected to know the alignment constraints
2347 * and respect them accordingly */
2348 bio
= bio_map_user_iov(q
, NULL
, iov
, iov_count
, rq_data_dir(rq
)== READ
);
2350 return PTR_ERR(bio
);
2352 rq
->bio
= rq
->biotail
= bio
;
2353 blk_rq_bio_prep(q
, rq
, bio
);
2354 rq
->buffer
= rq
->data
= NULL
;
2355 rq
->data_len
= bio
->bi_size
;
2359 EXPORT_SYMBOL(blk_rq_map_user_iov
);
2362 * blk_rq_unmap_user - unmap a request with user data
2363 * @bio: bio to be unmapped
2364 * @ulen: length of user buffer
2367 * Unmap a bio previously mapped by blk_rq_map_user().
2369 int blk_rq_unmap_user(struct bio
*bio
, unsigned int ulen
)
2374 if (bio_flagged(bio
, BIO_USER_MAPPED
))
2375 bio_unmap_user(bio
);
2377 ret
= bio_uncopy_user(bio
);
2383 EXPORT_SYMBOL(blk_rq_unmap_user
);
2386 * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage
2387 * @q: request queue where request should be inserted
2388 * @rq: request to fill
2389 * @kbuf: the kernel buffer
2390 * @len: length of user data
2391 * @gfp_mask: memory allocation flags
2393 int blk_rq_map_kern(request_queue_t
*q
, struct request
*rq
, void *kbuf
,
2394 unsigned int len
, gfp_t gfp_mask
)
2398 if (len
> (q
->max_hw_sectors
<< 9))
2403 bio
= bio_map_kern(q
, kbuf
, len
, gfp_mask
);
2405 return PTR_ERR(bio
);
2407 if (rq_data_dir(rq
) == WRITE
)
2408 bio
->bi_rw
|= (1 << BIO_RW
);
2410 rq
->bio
= rq
->biotail
= bio
;
2411 blk_rq_bio_prep(q
, rq
, bio
);
2413 rq
->buffer
= rq
->data
= NULL
;
2418 EXPORT_SYMBOL(blk_rq_map_kern
);
2421 * blk_execute_rq_nowait - insert a request into queue for execution
2422 * @q: queue to insert the request in
2423 * @bd_disk: matching gendisk
2424 * @rq: request to insert
2425 * @at_head: insert request at head or tail of queue
2426 * @done: I/O completion handler
2429 * Insert a fully prepared request at the back of the io scheduler queue
2430 * for execution. Don't wait for completion.
2432 void blk_execute_rq_nowait(request_queue_t
*q
, struct gendisk
*bd_disk
,
2433 struct request
*rq
, int at_head
,
2436 int where
= at_head
? ELEVATOR_INSERT_FRONT
: ELEVATOR_INSERT_BACK
;
2438 rq
->rq_disk
= bd_disk
;
2439 rq
->flags
|= REQ_NOMERGE
;
2441 elv_add_request(q
, rq
, where
, 1);
2442 generic_unplug_device(q
);
2445 EXPORT_SYMBOL_GPL(blk_execute_rq_nowait
);
2448 * blk_execute_rq - insert a request into queue for execution
2449 * @q: queue to insert the request in
2450 * @bd_disk: matching gendisk
2451 * @rq: request to insert
2452 * @at_head: insert request at head or tail of queue
2455 * Insert a fully prepared request at the back of the io scheduler queue
2456 * for execution and wait for completion.
2458 int blk_execute_rq(request_queue_t
*q
, struct gendisk
*bd_disk
,
2459 struct request
*rq
, int at_head
)
2461 DECLARE_COMPLETION(wait
);
2462 char sense
[SCSI_SENSE_BUFFERSIZE
];
2466 * we need an extra reference to the request, so we can look at
2467 * it after io completion
2472 memset(sense
, 0, sizeof(sense
));
2477 rq
->waiting
= &wait
;
2478 blk_execute_rq_nowait(q
, bd_disk
, rq
, at_head
, blk_end_sync_rq
);
2479 wait_for_completion(&wait
);
2488 EXPORT_SYMBOL(blk_execute_rq
);
2491 * blkdev_issue_flush - queue a flush
2492 * @bdev: blockdev to issue flush for
2493 * @error_sector: error sector
2496 * Issue a flush for the block device in question. Caller can supply
2497 * room for storing the error offset in case of a flush error, if they
2498 * wish to. Caller must run wait_for_completion() on its own.
2500 int blkdev_issue_flush(struct block_device
*bdev
, sector_t
*error_sector
)
2504 if (bdev
->bd_disk
== NULL
)
2507 q
= bdev_get_queue(bdev
);
2510 if (!q
->issue_flush_fn
)
2513 return q
->issue_flush_fn(q
, bdev
->bd_disk
, error_sector
);
2516 EXPORT_SYMBOL(blkdev_issue_flush
);
2518 static void drive_stat_acct(struct request
*rq
, int nr_sectors
, int new_io
)
2520 int rw
= rq_data_dir(rq
);
2522 if (!blk_fs_request(rq
) || !rq
->rq_disk
)
2526 __disk_stat_inc(rq
->rq_disk
, merges
[rw
]);
2528 disk_round_stats(rq
->rq_disk
);
2529 rq
->rq_disk
->in_flight
++;
2534 * add-request adds a request to the linked list.
2535 * queue lock is held and interrupts disabled, as we muck with the
2536 * request queue list.
2538 static inline void add_request(request_queue_t
* q
, struct request
* req
)
2540 drive_stat_acct(req
, req
->nr_sectors
, 1);
2543 q
->activity_fn(q
->activity_data
, rq_data_dir(req
));
2546 * elevator indicated where it wants this request to be
2547 * inserted at elevator_merge time
2549 __elv_add_request(q
, req
, ELEVATOR_INSERT_SORT
, 0);
2553 * disk_round_stats() - Round off the performance stats on a struct
2556 * The average IO queue length and utilisation statistics are maintained
2557 * by observing the current state of the queue length and the amount of
2558 * time it has been in this state for.
2560 * Normally, that accounting is done on IO completion, but that can result
2561 * in more than a second's worth of IO being accounted for within any one
2562 * second, leading to >100% utilisation. To deal with that, we call this
2563 * function to do a round-off before returning the results when reading
2564 * /proc/diskstats. This accounts immediately for all queue usage up to
2565 * the current jiffies and restarts the counters again.
2567 void disk_round_stats(struct gendisk
*disk
)
2569 unsigned long now
= jiffies
;
2571 if (now
== disk
->stamp
)
2574 if (disk
->in_flight
) {
2575 __disk_stat_add(disk
, time_in_queue
,
2576 disk
->in_flight
* (now
- disk
->stamp
));
2577 __disk_stat_add(disk
, io_ticks
, (now
- disk
->stamp
));
2582 EXPORT_SYMBOL_GPL(disk_round_stats
);
2585 * queue lock must be held
2587 void __blk_put_request(request_queue_t
*q
, struct request
*req
)
2589 struct request_list
*rl
= req
->rl
;
2593 if (unlikely(--req
->ref_count
))
2596 elv_completed_request(q
, req
);
2598 req
->rq_status
= RQ_INACTIVE
;
2602 * Request may not have originated from ll_rw_blk. if not,
2603 * it didn't come out of our reserved rq pools
2606 int rw
= rq_data_dir(req
);
2607 int priv
= req
->flags
& REQ_ELVPRIV
;
2609 BUG_ON(!list_empty(&req
->queuelist
));
2611 blk_free_request(q
, req
);
2612 freed_request(q
, rw
, priv
);
2616 EXPORT_SYMBOL_GPL(__blk_put_request
);
2618 void blk_put_request(struct request
*req
)
2620 unsigned long flags
;
2621 request_queue_t
*q
= req
->q
;
2624 * Gee, IDE calls in w/ NULL q. Fix IDE and remove the
2625 * following if (q) test.
2628 spin_lock_irqsave(q
->queue_lock
, flags
);
2629 __blk_put_request(q
, req
);
2630 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2634 EXPORT_SYMBOL(blk_put_request
);
2637 * blk_end_sync_rq - executes a completion event on a request
2638 * @rq: request to complete
2639 * @error: end io status of the request
2641 void blk_end_sync_rq(struct request
*rq
, int error
)
2643 struct completion
*waiting
= rq
->waiting
;
2646 __blk_put_request(rq
->q
, rq
);
2649 * complete last, if this is a stack request the process (and thus
2650 * the rq pointer) could be invalid right after this complete()
2654 EXPORT_SYMBOL(blk_end_sync_rq
);
2657 * blk_congestion_wait - wait for a queue to become uncongested
2658 * @rw: READ or WRITE
2659 * @timeout: timeout in jiffies
2661 * Waits for up to @timeout jiffies for a queue (any queue) to exit congestion.
2662 * If no queues are congested then just wait for the next request to be
2665 long blk_congestion_wait(int rw
, long timeout
)
2669 wait_queue_head_t
*wqh
= &congestion_wqh
[rw
];
2671 prepare_to_wait(wqh
, &wait
, TASK_UNINTERRUPTIBLE
);
2672 ret
= io_schedule_timeout(timeout
);
2673 finish_wait(wqh
, &wait
);
2677 EXPORT_SYMBOL(blk_congestion_wait
);
2680 * Has to be called with the request spinlock acquired
2682 static int attempt_merge(request_queue_t
*q
, struct request
*req
,
2683 struct request
*next
)
2685 if (!rq_mergeable(req
) || !rq_mergeable(next
))
2691 if (req
->sector
+ req
->nr_sectors
!= next
->sector
)
2694 if (rq_data_dir(req
) != rq_data_dir(next
)
2695 || req
->rq_disk
!= next
->rq_disk
2696 || next
->waiting
|| next
->special
)
2700 * If we are allowed to merge, then append bio list
2701 * from next to rq and release next. merge_requests_fn
2702 * will have updated segment counts, update sector
2705 if (!q
->merge_requests_fn(q
, req
, next
))
2709 * At this point we have either done a back merge
2710 * or front merge. We need the smaller start_time of
2711 * the merged requests to be the current request
2712 * for accounting purposes.
2714 if (time_after(req
->start_time
, next
->start_time
))
2715 req
->start_time
= next
->start_time
;
2717 req
->biotail
->bi_next
= next
->bio
;
2718 req
->biotail
= next
->biotail
;
2720 req
->nr_sectors
= req
->hard_nr_sectors
+= next
->hard_nr_sectors
;
2722 elv_merge_requests(q
, req
, next
);
2725 disk_round_stats(req
->rq_disk
);
2726 req
->rq_disk
->in_flight
--;
2729 req
->ioprio
= ioprio_best(req
->ioprio
, next
->ioprio
);
2731 __blk_put_request(q
, next
);
2735 static inline int attempt_back_merge(request_queue_t
*q
, struct request
*rq
)
2737 struct request
*next
= elv_latter_request(q
, rq
);
2740 return attempt_merge(q
, rq
, next
);
2745 static inline int attempt_front_merge(request_queue_t
*q
, struct request
*rq
)
2747 struct request
*prev
= elv_former_request(q
, rq
);
2750 return attempt_merge(q
, prev
, rq
);
2755 static void init_request_from_bio(struct request
*req
, struct bio
*bio
)
2757 req
->flags
|= REQ_CMD
;
2760 * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
2762 if (bio_rw_ahead(bio
) || bio_failfast(bio
))
2763 req
->flags
|= REQ_FAILFAST
;
2766 * REQ_BARRIER implies no merging, but lets make it explicit
2768 if (unlikely(bio_barrier(bio
)))
2769 req
->flags
|= (REQ_HARDBARRIER
| REQ_NOMERGE
);
2772 req
->hard_sector
= req
->sector
= bio
->bi_sector
;
2773 req
->hard_nr_sectors
= req
->nr_sectors
= bio_sectors(bio
);
2774 req
->current_nr_sectors
= req
->hard_cur_sectors
= bio_cur_sectors(bio
);
2775 req
->nr_phys_segments
= bio_phys_segments(req
->q
, bio
);
2776 req
->nr_hw_segments
= bio_hw_segments(req
->q
, bio
);
2777 req
->buffer
= bio_data(bio
); /* see ->buffer comment above */
2778 req
->waiting
= NULL
;
2779 req
->bio
= req
->biotail
= bio
;
2780 req
->ioprio
= bio_prio(bio
);
2781 req
->rq_disk
= bio
->bi_bdev
->bd_disk
;
2782 req
->start_time
= jiffies
;
2785 static int __make_request(request_queue_t
*q
, struct bio
*bio
)
2787 struct request
*req
;
2788 int el_ret
, rw
, nr_sectors
, cur_nr_sectors
, barrier
, err
, sync
;
2789 unsigned short prio
;
2792 sector
= bio
->bi_sector
;
2793 nr_sectors
= bio_sectors(bio
);
2794 cur_nr_sectors
= bio_cur_sectors(bio
);
2795 prio
= bio_prio(bio
);
2797 rw
= bio_data_dir(bio
);
2798 sync
= bio_sync(bio
);
2801 * low level driver can indicate that it wants pages above a
2802 * certain limit bounced to low memory (ie for highmem, or even
2803 * ISA dma in theory)
2805 blk_queue_bounce(q
, &bio
);
2807 spin_lock_prefetch(q
->queue_lock
);
2809 barrier
= bio_barrier(bio
);
2810 if (unlikely(barrier
) && (q
->next_ordered
== QUEUE_ORDERED_NONE
)) {
2815 spin_lock_irq(q
->queue_lock
);
2817 if (unlikely(barrier
) || elv_queue_empty(q
))
2820 el_ret
= elv_merge(q
, &req
, bio
);
2822 case ELEVATOR_BACK_MERGE
:
2823 BUG_ON(!rq_mergeable(req
));
2825 if (!q
->back_merge_fn(q
, req
, bio
))
2828 req
->biotail
->bi_next
= bio
;
2830 req
->nr_sectors
= req
->hard_nr_sectors
+= nr_sectors
;
2831 req
->ioprio
= ioprio_best(req
->ioprio
, prio
);
2832 drive_stat_acct(req
, nr_sectors
, 0);
2833 if (!attempt_back_merge(q
, req
))
2834 elv_merged_request(q
, req
);
2837 case ELEVATOR_FRONT_MERGE
:
2838 BUG_ON(!rq_mergeable(req
));
2840 if (!q
->front_merge_fn(q
, req
, bio
))
2843 bio
->bi_next
= req
->bio
;
2847 * may not be valid. if the low level driver said
2848 * it didn't need a bounce buffer then it better
2849 * not touch req->buffer either...
2851 req
->buffer
= bio_data(bio
);
2852 req
->current_nr_sectors
= cur_nr_sectors
;
2853 req
->hard_cur_sectors
= cur_nr_sectors
;
2854 req
->sector
= req
->hard_sector
= sector
;
2855 req
->nr_sectors
= req
->hard_nr_sectors
+= nr_sectors
;
2856 req
->ioprio
= ioprio_best(req
->ioprio
, prio
);
2857 drive_stat_acct(req
, nr_sectors
, 0);
2858 if (!attempt_front_merge(q
, req
))
2859 elv_merged_request(q
, req
);
2862 /* ELV_NO_MERGE: elevator says don't/can't merge. */
2869 * Grab a free request. This is might sleep but can not fail.
2870 * Returns with the queue unlocked.
2872 req
= get_request_wait(q
, rw
, bio
);
2875 * After dropping the lock and possibly sleeping here, our request
2876 * may now be mergeable after it had proven unmergeable (above).
2877 * We don't worry about that case for efficiency. It won't happen
2878 * often, and the elevators are able to handle it.
2880 init_request_from_bio(req
, bio
);
2882 spin_lock_irq(q
->queue_lock
);
2883 if (elv_queue_empty(q
))
2885 add_request(q
, req
);
2888 __generic_unplug_device(q
);
2890 spin_unlock_irq(q
->queue_lock
);
2894 bio_endio(bio
, nr_sectors
<< 9, err
);
2899 * If bio->bi_dev is a partition, remap the location
2901 static inline void blk_partition_remap(struct bio
*bio
)
2903 struct block_device
*bdev
= bio
->bi_bdev
;
2905 if (bdev
!= bdev
->bd_contains
) {
2906 struct hd_struct
*p
= bdev
->bd_part
;
2907 const int rw
= bio_data_dir(bio
);
2909 p
->sectors
[rw
] += bio_sectors(bio
);
2912 bio
->bi_sector
+= p
->start_sect
;
2913 bio
->bi_bdev
= bdev
->bd_contains
;
2917 static void handle_bad_sector(struct bio
*bio
)
2919 char b
[BDEVNAME_SIZE
];
2921 printk(KERN_INFO
"attempt to access beyond end of device\n");
2922 printk(KERN_INFO
"%s: rw=%ld, want=%Lu, limit=%Lu\n",
2923 bdevname(bio
->bi_bdev
, b
),
2925 (unsigned long long)bio
->bi_sector
+ bio_sectors(bio
),
2926 (long long)(bio
->bi_bdev
->bd_inode
->i_size
>> 9));
2928 set_bit(BIO_EOF
, &bio
->bi_flags
);
2932 * generic_make_request: hand a buffer to its device driver for I/O
2933 * @bio: The bio describing the location in memory and on the device.
2935 * generic_make_request() is used to make I/O requests of block
2936 * devices. It is passed a &struct bio, which describes the I/O that needs
2939 * generic_make_request() does not return any status. The
2940 * success/failure status of the request, along with notification of
2941 * completion, is delivered asynchronously through the bio->bi_end_io
2942 * function described (one day) else where.
2944 * The caller of generic_make_request must make sure that bi_io_vec
2945 * are set to describe the memory buffer, and that bi_dev and bi_sector are
2946 * set to describe the device address, and the
2947 * bi_end_io and optionally bi_private are set to describe how
2948 * completion notification should be signaled.
2950 * generic_make_request and the drivers it calls may use bi_next if this
2951 * bio happens to be merged with someone else, and may change bi_dev and
2952 * bi_sector for remaps as it sees fit. So the values of these fields
2953 * should NOT be depended on after the call to generic_make_request.
2955 void generic_make_request(struct bio
*bio
)
2959 int ret
, nr_sectors
= bio_sectors(bio
);
2962 /* Test device or partition size, when known. */
2963 maxsector
= bio
->bi_bdev
->bd_inode
->i_size
>> 9;
2965 sector_t sector
= bio
->bi_sector
;
2967 if (maxsector
< nr_sectors
|| maxsector
- nr_sectors
< sector
) {
2969 * This may well happen - the kernel calls bread()
2970 * without checking the size of the device, e.g., when
2971 * mounting a device.
2973 handle_bad_sector(bio
);
2979 * Resolve the mapping until finished. (drivers are
2980 * still free to implement/resolve their own stacking
2981 * by explicitly returning 0)
2983 * NOTE: we don't repeat the blk_size check for each new device.
2984 * Stacking drivers are expected to know what they are doing.
2987 char b
[BDEVNAME_SIZE
];
2989 q
= bdev_get_queue(bio
->bi_bdev
);
2992 "generic_make_request: Trying to access "
2993 "nonexistent block-device %s (%Lu)\n",
2994 bdevname(bio
->bi_bdev
, b
),
2995 (long long) bio
->bi_sector
);
2997 bio_endio(bio
, bio
->bi_size
, -EIO
);
3001 if (unlikely(bio_sectors(bio
) > q
->max_hw_sectors
)) {
3002 printk("bio too big device %s (%u > %u)\n",
3003 bdevname(bio
->bi_bdev
, b
),
3009 if (unlikely(test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
)))
3013 * If this device has partitions, remap block n
3014 * of partition p to block n+start(p) of the disk.
3016 blk_partition_remap(bio
);
3018 ret
= q
->make_request_fn(q
, bio
);
3022 EXPORT_SYMBOL(generic_make_request
);
3025 * submit_bio: submit a bio to the block device layer for I/O
3026 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
3027 * @bio: The &struct bio which describes the I/O
3029 * submit_bio() is very similar in purpose to generic_make_request(), and
3030 * uses that function to do most of the work. Both are fairly rough
3031 * interfaces, @bio must be presetup and ready for I/O.
3034 void submit_bio(int rw
, struct bio
*bio
)
3036 int count
= bio_sectors(bio
);
3038 BIO_BUG_ON(!bio
->bi_size
);
3039 BIO_BUG_ON(!bio
->bi_io_vec
);
3042 mod_page_state(pgpgout
, count
);
3044 mod_page_state(pgpgin
, count
);
3046 if (unlikely(block_dump
)) {
3047 char b
[BDEVNAME_SIZE
];
3048 printk(KERN_DEBUG
"%s(%d): %s block %Lu on %s\n",
3049 current
->comm
, current
->pid
,
3050 (rw
& WRITE
) ? "WRITE" : "READ",
3051 (unsigned long long)bio
->bi_sector
,
3052 bdevname(bio
->bi_bdev
,b
));
3055 generic_make_request(bio
);
3058 EXPORT_SYMBOL(submit_bio
);
3060 static void blk_recalc_rq_segments(struct request
*rq
)
3062 struct bio
*bio
, *prevbio
= NULL
;
3063 int nr_phys_segs
, nr_hw_segs
;
3064 unsigned int phys_size
, hw_size
;
3065 request_queue_t
*q
= rq
->q
;
3070 phys_size
= hw_size
= nr_phys_segs
= nr_hw_segs
= 0;
3071 rq_for_each_bio(bio
, rq
) {
3072 /* Force bio hw/phys segs to be recalculated. */
3073 bio
->bi_flags
&= ~(1 << BIO_SEG_VALID
);
3075 nr_phys_segs
+= bio_phys_segments(q
, bio
);
3076 nr_hw_segs
+= bio_hw_segments(q
, bio
);
3078 int pseg
= phys_size
+ prevbio
->bi_size
+ bio
->bi_size
;
3079 int hseg
= hw_size
+ prevbio
->bi_size
+ bio
->bi_size
;
3081 if (blk_phys_contig_segment(q
, prevbio
, bio
) &&
3082 pseg
<= q
->max_segment_size
) {
3084 phys_size
+= prevbio
->bi_size
+ bio
->bi_size
;
3088 if (blk_hw_contig_segment(q
, prevbio
, bio
) &&
3089 hseg
<= q
->max_segment_size
) {
3091 hw_size
+= prevbio
->bi_size
+ bio
->bi_size
;
3098 rq
->nr_phys_segments
= nr_phys_segs
;
3099 rq
->nr_hw_segments
= nr_hw_segs
;
3102 static void blk_recalc_rq_sectors(struct request
*rq
, int nsect
)
3104 if (blk_fs_request(rq
)) {
3105 rq
->hard_sector
+= nsect
;
3106 rq
->hard_nr_sectors
-= nsect
;
3109 * Move the I/O submission pointers ahead if required.
3111 if ((rq
->nr_sectors
>= rq
->hard_nr_sectors
) &&
3112 (rq
->sector
<= rq
->hard_sector
)) {
3113 rq
->sector
= rq
->hard_sector
;
3114 rq
->nr_sectors
= rq
->hard_nr_sectors
;
3115 rq
->hard_cur_sectors
= bio_cur_sectors(rq
->bio
);
3116 rq
->current_nr_sectors
= rq
->hard_cur_sectors
;
3117 rq
->buffer
= bio_data(rq
->bio
);
3121 * if total number of sectors is less than the first segment
3122 * size, something has gone terribly wrong
3124 if (rq
->nr_sectors
< rq
->current_nr_sectors
) {
3125 printk("blk: request botched\n");
3126 rq
->nr_sectors
= rq
->current_nr_sectors
;
3131 static int __end_that_request_first(struct request
*req
, int uptodate
,
3134 int total_bytes
, bio_nbytes
, error
, next_idx
= 0;
3138 * extend uptodate bool to allow < 0 value to be direct io error
3141 if (end_io_error(uptodate
))
3142 error
= !uptodate
? -EIO
: uptodate
;
3145 * for a REQ_BLOCK_PC request, we want to carry any eventual
3146 * sense key with us all the way through
3148 if (!blk_pc_request(req
))
3152 if (blk_fs_request(req
) && !(req
->flags
& REQ_QUIET
))
3153 printk("end_request: I/O error, dev %s, sector %llu\n",
3154 req
->rq_disk
? req
->rq_disk
->disk_name
: "?",
3155 (unsigned long long)req
->sector
);
3158 if (blk_fs_request(req
) && req
->rq_disk
) {
3159 const int rw
= rq_data_dir(req
);
3161 disk_stat_add(req
->rq_disk
, sectors
[rw
], nr_bytes
>> 9);
3164 total_bytes
= bio_nbytes
= 0;
3165 while ((bio
= req
->bio
) != NULL
) {
3168 if (nr_bytes
>= bio
->bi_size
) {
3169 req
->bio
= bio
->bi_next
;
3170 nbytes
= bio
->bi_size
;
3171 if (!ordered_bio_endio(req
, bio
, nbytes
, error
))
3172 bio_endio(bio
, nbytes
, error
);
3176 int idx
= bio
->bi_idx
+ next_idx
;
3178 if (unlikely(bio
->bi_idx
>= bio
->bi_vcnt
)) {
3179 blk_dump_rq_flags(req
, "__end_that");
3180 printk("%s: bio idx %d >= vcnt %d\n",
3182 bio
->bi_idx
, bio
->bi_vcnt
);
3186 nbytes
= bio_iovec_idx(bio
, idx
)->bv_len
;
3187 BIO_BUG_ON(nbytes
> bio
->bi_size
);
3190 * not a complete bvec done
3192 if (unlikely(nbytes
> nr_bytes
)) {
3193 bio_nbytes
+= nr_bytes
;
3194 total_bytes
+= nr_bytes
;
3199 * advance to the next vector
3202 bio_nbytes
+= nbytes
;
3205 total_bytes
+= nbytes
;
3208 if ((bio
= req
->bio
)) {
3210 * end more in this run, or just return 'not-done'
3212 if (unlikely(nr_bytes
<= 0))
3224 * if the request wasn't completed, update state
3227 if (!ordered_bio_endio(req
, bio
, bio_nbytes
, error
))
3228 bio_endio(bio
, bio_nbytes
, error
);
3229 bio
->bi_idx
+= next_idx
;
3230 bio_iovec(bio
)->bv_offset
+= nr_bytes
;
3231 bio_iovec(bio
)->bv_len
-= nr_bytes
;
3234 blk_recalc_rq_sectors(req
, total_bytes
>> 9);
3235 blk_recalc_rq_segments(req
);
3240 * end_that_request_first - end I/O on a request
3241 * @req: the request being processed
3242 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3243 * @nr_sectors: number of sectors to end I/O on
3246 * Ends I/O on a number of sectors attached to @req, and sets it up
3247 * for the next range of segments (if any) in the cluster.
3250 * 0 - we are done with this request, call end_that_request_last()
3251 * 1 - still buffers pending for this request
3253 int end_that_request_first(struct request
*req
, int uptodate
, int nr_sectors
)
3255 return __end_that_request_first(req
, uptodate
, nr_sectors
<< 9);
3258 EXPORT_SYMBOL(end_that_request_first
);
3261 * end_that_request_chunk - end I/O on a request
3262 * @req: the request being processed
3263 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3264 * @nr_bytes: number of bytes to complete
3267 * Ends I/O on a number of bytes attached to @req, and sets it up
3268 * for the next range of segments (if any). Like end_that_request_first(),
3269 * but deals with bytes instead of sectors.
3272 * 0 - we are done with this request, call end_that_request_last()
3273 * 1 - still buffers pending for this request
3275 int end_that_request_chunk(struct request
*req
, int uptodate
, int nr_bytes
)
3277 return __end_that_request_first(req
, uptodate
, nr_bytes
);
3280 EXPORT_SYMBOL(end_that_request_chunk
);
3283 * splice the completion data to a local structure and hand off to
3284 * process_completion_queue() to complete the requests
3286 static void blk_done_softirq(struct softirq_action
*h
)
3288 struct list_head
*cpu_list
;
3289 LIST_HEAD(local_list
);
3291 local_irq_disable();
3292 cpu_list
= &__get_cpu_var(blk_cpu_done
);
3293 list_splice_init(cpu_list
, &local_list
);
3296 while (!list_empty(&local_list
)) {
3297 struct request
*rq
= list_entry(local_list
.next
, struct request
, donelist
);
3299 list_del_init(&rq
->donelist
);
3300 rq
->q
->softirq_done_fn(rq
);
3304 #ifdef CONFIG_HOTPLUG_CPU
3306 static int blk_cpu_notify(struct notifier_block
*self
, unsigned long action
,
3310 * If a CPU goes away, splice its entries to the current CPU
3311 * and trigger a run of the softirq
3313 if (action
== CPU_DEAD
) {
3314 int cpu
= (unsigned long) hcpu
;
3316 local_irq_disable();
3317 list_splice_init(&per_cpu(blk_cpu_done
, cpu
),
3318 &__get_cpu_var(blk_cpu_done
));
3319 raise_softirq_irqoff(BLOCK_SOFTIRQ
);
3327 static struct notifier_block __devinitdata blk_cpu_notifier
= {
3328 .notifier_call
= blk_cpu_notify
,
3331 #endif /* CONFIG_HOTPLUG_CPU */
3334 * blk_complete_request - end I/O on a request
3335 * @req: the request being processed
3338 * Ends all I/O on a request. It does not handle partial completions,
3339 * unless the driver actually implements this in its completionc callback
3340 * through requeueing. Theh actual completion happens out-of-order,
3341 * through a softirq handler. The user must have registered a completion
3342 * callback through blk_queue_softirq_done().
3345 void blk_complete_request(struct request
*req
)
3347 struct list_head
*cpu_list
;
3348 unsigned long flags
;
3350 BUG_ON(!req
->q
->softirq_done_fn
);
3352 local_irq_save(flags
);
3354 cpu_list
= &__get_cpu_var(blk_cpu_done
);
3355 list_add_tail(&req
->donelist
, cpu_list
);
3356 raise_softirq_irqoff(BLOCK_SOFTIRQ
);
3358 local_irq_restore(flags
);
3361 EXPORT_SYMBOL(blk_complete_request
);
3364 * queue lock must be held
3366 void end_that_request_last(struct request
*req
, int uptodate
)
3368 struct gendisk
*disk
= req
->rq_disk
;
3372 * extend uptodate bool to allow < 0 value to be direct io error
3375 if (end_io_error(uptodate
))
3376 error
= !uptodate
? -EIO
: uptodate
;
3378 if (unlikely(laptop_mode
) && blk_fs_request(req
))
3379 laptop_io_completion();
3381 if (disk
&& blk_fs_request(req
)) {
3382 unsigned long duration
= jiffies
- req
->start_time
;
3383 const int rw
= rq_data_dir(req
);
3385 __disk_stat_inc(disk
, ios
[rw
]);
3386 __disk_stat_add(disk
, ticks
[rw
], duration
);
3387 disk_round_stats(disk
);
3391 req
->end_io(req
, error
);
3393 __blk_put_request(req
->q
, req
);
3396 EXPORT_SYMBOL(end_that_request_last
);
3398 void end_request(struct request
*req
, int uptodate
)
3400 if (!end_that_request_first(req
, uptodate
, req
->hard_cur_sectors
)) {
3401 add_disk_randomness(req
->rq_disk
);
3402 blkdev_dequeue_request(req
);
3403 end_that_request_last(req
, uptodate
);
3407 EXPORT_SYMBOL(end_request
);
3409 void blk_rq_bio_prep(request_queue_t
*q
, struct request
*rq
, struct bio
*bio
)
3411 /* first three bits are identical in rq->flags and bio->bi_rw */
3412 rq
->flags
|= (bio
->bi_rw
& 7);
3414 rq
->nr_phys_segments
= bio_phys_segments(q
, bio
);
3415 rq
->nr_hw_segments
= bio_hw_segments(q
, bio
);
3416 rq
->current_nr_sectors
= bio_cur_sectors(bio
);
3417 rq
->hard_cur_sectors
= rq
->current_nr_sectors
;
3418 rq
->hard_nr_sectors
= rq
->nr_sectors
= bio_sectors(bio
);
3419 rq
->buffer
= bio_data(bio
);
3421 rq
->bio
= rq
->biotail
= bio
;
3424 EXPORT_SYMBOL(blk_rq_bio_prep
);
3426 int kblockd_schedule_work(struct work_struct
*work
)
3428 return queue_work(kblockd_workqueue
, work
);
3431 EXPORT_SYMBOL(kblockd_schedule_work
);
3433 void kblockd_flush(void)
3435 flush_workqueue(kblockd_workqueue
);
3437 EXPORT_SYMBOL(kblockd_flush
);
3439 int __init
blk_dev_init(void)
3443 kblockd_workqueue
= create_workqueue("kblockd");
3444 if (!kblockd_workqueue
)
3445 panic("Failed to create kblockd\n");
3447 request_cachep
= kmem_cache_create("blkdev_requests",
3448 sizeof(struct request
), 0, SLAB_PANIC
, NULL
, NULL
);
3450 requestq_cachep
= kmem_cache_create("blkdev_queue",
3451 sizeof(request_queue_t
), 0, SLAB_PANIC
, NULL
, NULL
);
3453 iocontext_cachep
= kmem_cache_create("blkdev_ioc",
3454 sizeof(struct io_context
), 0, SLAB_PANIC
, NULL
, NULL
);
3456 for (i
= 0; i
< NR_CPUS
; i
++)
3457 INIT_LIST_HEAD(&per_cpu(blk_cpu_done
, i
));
3459 open_softirq(BLOCK_SOFTIRQ
, blk_done_softirq
, NULL
);
3460 #ifdef CONFIG_HOTPLUG_CPU
3461 register_cpu_notifier(&blk_cpu_notifier
);
3464 blk_max_low_pfn
= max_low_pfn
;
3465 blk_max_pfn
= max_pfn
;
3471 * IO Context helper functions
3473 void put_io_context(struct io_context
*ioc
)
3478 BUG_ON(atomic_read(&ioc
->refcount
) == 0);
3480 if (atomic_dec_and_test(&ioc
->refcount
)) {
3481 if (ioc
->aic
&& ioc
->aic
->dtor
)
3482 ioc
->aic
->dtor(ioc
->aic
);
3483 if (ioc
->cic
&& ioc
->cic
->dtor
)
3484 ioc
->cic
->dtor(ioc
->cic
);
3486 kmem_cache_free(iocontext_cachep
, ioc
);
3489 EXPORT_SYMBOL(put_io_context
);
3491 /* Called by the exitting task */
3492 void exit_io_context(void)
3494 unsigned long flags
;
3495 struct io_context
*ioc
;
3497 local_irq_save(flags
);
3499 ioc
= current
->io_context
;
3500 current
->io_context
= NULL
;
3502 task_unlock(current
);
3503 local_irq_restore(flags
);
3505 if (ioc
->aic
&& ioc
->aic
->exit
)
3506 ioc
->aic
->exit(ioc
->aic
);
3507 if (ioc
->cic
&& ioc
->cic
->exit
)
3508 ioc
->cic
->exit(ioc
->cic
);
3510 put_io_context(ioc
);
3514 * If the current task has no IO context then create one and initialise it.
3515 * Otherwise, return its existing IO context.
3517 * This returned IO context doesn't have a specifically elevated refcount,
3518 * but since the current task itself holds a reference, the context can be
3519 * used in general code, so long as it stays within `current` context.
3521 struct io_context
*current_io_context(gfp_t gfp_flags
)
3523 struct task_struct
*tsk
= current
;
3524 struct io_context
*ret
;
3526 ret
= tsk
->io_context
;
3530 ret
= kmem_cache_alloc(iocontext_cachep
, gfp_flags
);
3532 atomic_set(&ret
->refcount
, 1);
3533 ret
->task
= current
;
3534 ret
->set_ioprio
= NULL
;
3535 ret
->last_waited
= jiffies
; /* doesn't matter... */
3536 ret
->nr_batch_requests
= 0; /* because this is 0 */
3539 tsk
->io_context
= ret
;
3544 EXPORT_SYMBOL(current_io_context
);
3547 * If the current task has no IO context then create one and initialise it.
3548 * If it does have a context, take a ref on it.
3550 * This is always called in the context of the task which submitted the I/O.
3552 struct io_context
*get_io_context(gfp_t gfp_flags
)
3554 struct io_context
*ret
;
3555 ret
= current_io_context(gfp_flags
);
3557 atomic_inc(&ret
->refcount
);
3560 EXPORT_SYMBOL(get_io_context
);
3562 void copy_io_context(struct io_context
**pdst
, struct io_context
**psrc
)
3564 struct io_context
*src
= *psrc
;
3565 struct io_context
*dst
= *pdst
;
3568 BUG_ON(atomic_read(&src
->refcount
) == 0);
3569 atomic_inc(&src
->refcount
);
3570 put_io_context(dst
);
3574 EXPORT_SYMBOL(copy_io_context
);
3576 void swap_io_context(struct io_context
**ioc1
, struct io_context
**ioc2
)
3578 struct io_context
*temp
;
3583 EXPORT_SYMBOL(swap_io_context
);
3588 struct queue_sysfs_entry
{
3589 struct attribute attr
;
3590 ssize_t (*show
)(struct request_queue
*, char *);
3591 ssize_t (*store
)(struct request_queue
*, const char *, size_t);
3595 queue_var_show(unsigned int var
, char *page
)
3597 return sprintf(page
, "%d\n", var
);
3601 queue_var_store(unsigned long *var
, const char *page
, size_t count
)
3603 char *p
= (char *) page
;
3605 *var
= simple_strtoul(p
, &p
, 10);
3609 static ssize_t
queue_requests_show(struct request_queue
*q
, char *page
)
3611 return queue_var_show(q
->nr_requests
, (page
));
3615 queue_requests_store(struct request_queue
*q
, const char *page
, size_t count
)
3617 struct request_list
*rl
= &q
->rq
;
3619 int ret
= queue_var_store(&q
->nr_requests
, page
, count
);
3620 if (q
->nr_requests
< BLKDEV_MIN_RQ
)
3621 q
->nr_requests
= BLKDEV_MIN_RQ
;
3622 blk_queue_congestion_threshold(q
);
3624 if (rl
->count
[READ
] >= queue_congestion_on_threshold(q
))
3625 set_queue_congested(q
, READ
);
3626 else if (rl
->count
[READ
] < queue_congestion_off_threshold(q
))
3627 clear_queue_congested(q
, READ
);
3629 if (rl
->count
[WRITE
] >= queue_congestion_on_threshold(q
))
3630 set_queue_congested(q
, WRITE
);
3631 else if (rl
->count
[WRITE
] < queue_congestion_off_threshold(q
))
3632 clear_queue_congested(q
, WRITE
);
3634 if (rl
->count
[READ
] >= q
->nr_requests
) {
3635 blk_set_queue_full(q
, READ
);
3636 } else if (rl
->count
[READ
]+1 <= q
->nr_requests
) {
3637 blk_clear_queue_full(q
, READ
);
3638 wake_up(&rl
->wait
[READ
]);
3641 if (rl
->count
[WRITE
] >= q
->nr_requests
) {
3642 blk_set_queue_full(q
, WRITE
);
3643 } else if (rl
->count
[WRITE
]+1 <= q
->nr_requests
) {
3644 blk_clear_queue_full(q
, WRITE
);
3645 wake_up(&rl
->wait
[WRITE
]);
3650 static ssize_t
queue_ra_show(struct request_queue
*q
, char *page
)
3652 int ra_kb
= q
->backing_dev_info
.ra_pages
<< (PAGE_CACHE_SHIFT
- 10);
3654 return queue_var_show(ra_kb
, (page
));
3658 queue_ra_store(struct request_queue
*q
, const char *page
, size_t count
)
3660 unsigned long ra_kb
;
3661 ssize_t ret
= queue_var_store(&ra_kb
, page
, count
);
3663 spin_lock_irq(q
->queue_lock
);
3664 if (ra_kb
> (q
->max_sectors
>> 1))
3665 ra_kb
= (q
->max_sectors
>> 1);
3667 q
->backing_dev_info
.ra_pages
= ra_kb
>> (PAGE_CACHE_SHIFT
- 10);
3668 spin_unlock_irq(q
->queue_lock
);
3673 static ssize_t
queue_max_sectors_show(struct request_queue
*q
, char *page
)
3675 int max_sectors_kb
= q
->max_sectors
>> 1;
3677 return queue_var_show(max_sectors_kb
, (page
));
3681 queue_max_sectors_store(struct request_queue
*q
, const char *page
, size_t count
)
3683 unsigned long max_sectors_kb
,
3684 max_hw_sectors_kb
= q
->max_hw_sectors
>> 1,
3685 page_kb
= 1 << (PAGE_CACHE_SHIFT
- 10);
3686 ssize_t ret
= queue_var_store(&max_sectors_kb
, page
, count
);
3689 if (max_sectors_kb
> max_hw_sectors_kb
|| max_sectors_kb
< page_kb
)
3692 * Take the queue lock to update the readahead and max_sectors
3693 * values synchronously:
3695 spin_lock_irq(q
->queue_lock
);
3697 * Trim readahead window as well, if necessary:
3699 ra_kb
= q
->backing_dev_info
.ra_pages
<< (PAGE_CACHE_SHIFT
- 10);
3700 if (ra_kb
> max_sectors_kb
)
3701 q
->backing_dev_info
.ra_pages
=
3702 max_sectors_kb
>> (PAGE_CACHE_SHIFT
- 10);
3704 q
->max_sectors
= max_sectors_kb
<< 1;
3705 spin_unlock_irq(q
->queue_lock
);
3710 static ssize_t
queue_max_hw_sectors_show(struct request_queue
*q
, char *page
)
3712 int max_hw_sectors_kb
= q
->max_hw_sectors
>> 1;
3714 return queue_var_show(max_hw_sectors_kb
, (page
));
3718 static struct queue_sysfs_entry queue_requests_entry
= {
3719 .attr
= {.name
= "nr_requests", .mode
= S_IRUGO
| S_IWUSR
},
3720 .show
= queue_requests_show
,
3721 .store
= queue_requests_store
,
3724 static struct queue_sysfs_entry queue_ra_entry
= {
3725 .attr
= {.name
= "read_ahead_kb", .mode
= S_IRUGO
| S_IWUSR
},
3726 .show
= queue_ra_show
,
3727 .store
= queue_ra_store
,
3730 static struct queue_sysfs_entry queue_max_sectors_entry
= {
3731 .attr
= {.name
= "max_sectors_kb", .mode
= S_IRUGO
| S_IWUSR
},
3732 .show
= queue_max_sectors_show
,
3733 .store
= queue_max_sectors_store
,
3736 static struct queue_sysfs_entry queue_max_hw_sectors_entry
= {
3737 .attr
= {.name
= "max_hw_sectors_kb", .mode
= S_IRUGO
},
3738 .show
= queue_max_hw_sectors_show
,
3741 static struct queue_sysfs_entry queue_iosched_entry
= {
3742 .attr
= {.name
= "scheduler", .mode
= S_IRUGO
| S_IWUSR
},
3743 .show
= elv_iosched_show
,
3744 .store
= elv_iosched_store
,
3747 static struct attribute
*default_attrs
[] = {
3748 &queue_requests_entry
.attr
,
3749 &queue_ra_entry
.attr
,
3750 &queue_max_hw_sectors_entry
.attr
,
3751 &queue_max_sectors_entry
.attr
,
3752 &queue_iosched_entry
.attr
,
3756 #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
3759 queue_attr_show(struct kobject
*kobj
, struct attribute
*attr
, char *page
)
3761 struct queue_sysfs_entry
*entry
= to_queue(attr
);
3762 struct request_queue
*q
;
3764 q
= container_of(kobj
, struct request_queue
, kobj
);
3768 return entry
->show(q
, page
);
3772 queue_attr_store(struct kobject
*kobj
, struct attribute
*attr
,
3773 const char *page
, size_t length
)
3775 struct queue_sysfs_entry
*entry
= to_queue(attr
);
3776 struct request_queue
*q
;
3778 q
= container_of(kobj
, struct request_queue
, kobj
);
3782 return entry
->store(q
, page
, length
);
3785 static struct sysfs_ops queue_sysfs_ops
= {
3786 .show
= queue_attr_show
,
3787 .store
= queue_attr_store
,
3790 static struct kobj_type queue_ktype
= {
3791 .sysfs_ops
= &queue_sysfs_ops
,
3792 .default_attrs
= default_attrs
,
3795 int blk_register_queue(struct gendisk
*disk
)
3799 request_queue_t
*q
= disk
->queue
;
3801 if (!q
|| !q
->request_fn
)
3804 q
->kobj
.parent
= kobject_get(&disk
->kobj
);
3805 if (!q
->kobj
.parent
)
3808 snprintf(q
->kobj
.name
, KOBJ_NAME_LEN
, "%s", "queue");
3809 q
->kobj
.ktype
= &queue_ktype
;
3811 ret
= kobject_register(&q
->kobj
);
3815 ret
= elv_register_queue(q
);
3817 kobject_unregister(&q
->kobj
);
3824 void blk_unregister_queue(struct gendisk
*disk
)
3826 request_queue_t
*q
= disk
->queue
;
3828 if (q
&& q
->request_fn
) {
3829 elv_unregister_queue(q
);
3831 kobject_unregister(&q
->kobj
);
3832 kobject_put(&disk
->kobj
);