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/kernel.h>
14 #include <linux/module.h>
15 #include <linux/backing-dev.h>
16 #include <linux/bio.h>
17 #include <linux/blkdev.h>
18 #include <linux/highmem.h>
20 #include <linux/kernel_stat.h>
21 #include <linux/string.h>
22 #include <linux/init.h>
23 #include <linux/bootmem.h> /* for max_pfn/max_low_pfn */
24 #include <linux/completion.h>
25 #include <linux/slab.h>
26 #include <linux/swap.h>
27 #include <linux/writeback.h>
28 #include <linux/interrupt.h>
29 #include <linux/cpu.h>
30 #include <linux/blktrace_api.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
->bio
= rq
->biotail
= NULL
;
287 INIT_HLIST_NODE(&rq
->hash
);
288 RB_CLEAR_NODE(&rq
->rb_node
);
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
->cmd_flags
& REQ_ORDERED_COLOR
) ==
386 (q
->orig_bar_rq
->cmd_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
;
449 rq
->cmd_flags
= REQ_HARDBARRIER
;
451 rq
->elevator_private
= NULL
;
452 rq
->elevator_private2
= NULL
;
453 rq
->rq_disk
= q
->bar_rq
.rq_disk
;
455 q
->prepare_flush_fn(q
, rq
);
457 elv_insert(q
, rq
, ELEVATOR_INSERT_FRONT
);
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
);
476 if (bio_data_dir(q
->orig_bar_rq
->bio
) == WRITE
)
477 rq
->cmd_flags
|= REQ_RW
;
478 rq
->cmd_flags
|= q
->ordered
& QUEUE_ORDERED_FUA
? REQ_FUA
: 0;
479 rq
->elevator_private
= NULL
;
480 rq
->elevator_private2
= NULL
;
481 init_request_from_bio(rq
, q
->orig_bar_rq
->bio
);
482 rq
->end_io
= bar_end_io
;
485 * Queue ordered sequence. As we stack them at the head, we
486 * need to queue in reverse order. Note that we rely on that
487 * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs
488 * request gets inbetween ordered sequence.
490 if (q
->ordered
& QUEUE_ORDERED_POSTFLUSH
)
491 queue_flush(q
, QUEUE_ORDERED_POSTFLUSH
);
493 q
->ordseq
|= QUEUE_ORDSEQ_POSTFLUSH
;
495 elv_insert(q
, rq
, ELEVATOR_INSERT_FRONT
);
497 if (q
->ordered
& QUEUE_ORDERED_PREFLUSH
) {
498 queue_flush(q
, QUEUE_ORDERED_PREFLUSH
);
499 rq
= &q
->pre_flush_rq
;
501 q
->ordseq
|= QUEUE_ORDSEQ_PREFLUSH
;
503 if ((q
->ordered
& QUEUE_ORDERED_TAG
) || q
->in_flight
== 0)
504 q
->ordseq
|= QUEUE_ORDSEQ_DRAIN
;
511 int blk_do_ordered(request_queue_t
*q
, struct request
**rqp
)
513 struct request
*rq
= *rqp
;
514 int is_barrier
= blk_fs_request(rq
) && blk_barrier_rq(rq
);
520 if (q
->next_ordered
!= QUEUE_ORDERED_NONE
) {
521 *rqp
= start_ordered(q
, rq
);
525 * This can happen when the queue switches to
526 * ORDERED_NONE while this request is on it.
528 blkdev_dequeue_request(rq
);
529 end_that_request_first(rq
, -EOPNOTSUPP
,
530 rq
->hard_nr_sectors
);
531 end_that_request_last(rq
, -EOPNOTSUPP
);
538 * Ordered sequence in progress
541 /* Special requests are not subject to ordering rules. */
542 if (!blk_fs_request(rq
) &&
543 rq
!= &q
->pre_flush_rq
&& rq
!= &q
->post_flush_rq
)
546 if (q
->ordered
& QUEUE_ORDERED_TAG
) {
547 /* Ordered by tag. Blocking the next barrier is enough. */
548 if (is_barrier
&& rq
!= &q
->bar_rq
)
551 /* Ordered by draining. Wait for turn. */
552 WARN_ON(blk_ordered_req_seq(rq
) < blk_ordered_cur_seq(q
));
553 if (blk_ordered_req_seq(rq
) > blk_ordered_cur_seq(q
))
560 static int flush_dry_bio_endio(struct bio
*bio
, unsigned int bytes
, int error
)
562 request_queue_t
*q
= bio
->bi_private
;
563 struct bio_vec
*bvec
;
567 * This is dry run, restore bio_sector and size. We'll finish
568 * this request again with the original bi_end_io after an
569 * error occurs or post flush is complete.
578 bio_for_each_segment(bvec
, bio
, i
) {
579 bvec
->bv_len
+= bvec
->bv_offset
;
584 set_bit(BIO_UPTODATE
, &bio
->bi_flags
);
585 bio
->bi_size
= q
->bi_size
;
586 bio
->bi_sector
-= (q
->bi_size
>> 9);
592 static inline int ordered_bio_endio(struct request
*rq
, struct bio
*bio
,
593 unsigned int nbytes
, int error
)
595 request_queue_t
*q
= rq
->q
;
599 if (&q
->bar_rq
!= rq
)
603 * Okay, this is the barrier request in progress, dry finish it.
605 if (error
&& !q
->orderr
)
608 endio
= bio
->bi_end_io
;
609 private = bio
->bi_private
;
610 bio
->bi_end_io
= flush_dry_bio_endio
;
613 bio_endio(bio
, nbytes
, error
);
615 bio
->bi_end_io
= endio
;
616 bio
->bi_private
= private;
622 * blk_queue_bounce_limit - set bounce buffer limit for queue
623 * @q: the request queue for the device
624 * @dma_addr: bus address limit
627 * Different hardware can have different requirements as to what pages
628 * it can do I/O directly to. A low level driver can call
629 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
630 * buffers for doing I/O to pages residing above @page.
632 void blk_queue_bounce_limit(request_queue_t
*q
, u64 dma_addr
)
634 unsigned long bounce_pfn
= dma_addr
>> PAGE_SHIFT
;
637 q
->bounce_gfp
= GFP_NOIO
;
638 #if BITS_PER_LONG == 64
639 /* Assume anything <= 4GB can be handled by IOMMU.
640 Actually some IOMMUs can handle everything, but I don't
641 know of a way to test this here. */
642 if (bounce_pfn
< (min_t(u64
,0xffffffff,BLK_BOUNCE_HIGH
) >> PAGE_SHIFT
))
644 q
->bounce_pfn
= max_low_pfn
;
646 if (bounce_pfn
< blk_max_low_pfn
)
648 q
->bounce_pfn
= bounce_pfn
;
651 init_emergency_isa_pool();
652 q
->bounce_gfp
= GFP_NOIO
| GFP_DMA
;
653 q
->bounce_pfn
= bounce_pfn
;
657 EXPORT_SYMBOL(blk_queue_bounce_limit
);
660 * blk_queue_max_sectors - set max sectors for a request for this queue
661 * @q: the request queue for the device
662 * @max_sectors: max sectors in the usual 512b unit
665 * Enables a low level driver to set an upper limit on the size of
668 void blk_queue_max_sectors(request_queue_t
*q
, unsigned int max_sectors
)
670 if ((max_sectors
<< 9) < PAGE_CACHE_SIZE
) {
671 max_sectors
= 1 << (PAGE_CACHE_SHIFT
- 9);
672 printk("%s: set to minimum %d\n", __FUNCTION__
, max_sectors
);
675 if (BLK_DEF_MAX_SECTORS
> max_sectors
)
676 q
->max_hw_sectors
= q
->max_sectors
= max_sectors
;
678 q
->max_sectors
= BLK_DEF_MAX_SECTORS
;
679 q
->max_hw_sectors
= max_sectors
;
683 EXPORT_SYMBOL(blk_queue_max_sectors
);
686 * blk_queue_max_phys_segments - set max phys segments for a request for this queue
687 * @q: the request queue for the device
688 * @max_segments: max number of segments
691 * Enables a low level driver to set an upper limit on the number of
692 * physical data segments in a request. This would be the largest sized
693 * scatter list the driver could handle.
695 void blk_queue_max_phys_segments(request_queue_t
*q
, unsigned short max_segments
)
699 printk("%s: set to minimum %d\n", __FUNCTION__
, max_segments
);
702 q
->max_phys_segments
= max_segments
;
705 EXPORT_SYMBOL(blk_queue_max_phys_segments
);
708 * blk_queue_max_hw_segments - set max hw segments for a request for this queue
709 * @q: the request queue for the device
710 * @max_segments: max number of segments
713 * Enables a low level driver to set an upper limit on the number of
714 * hw data segments in a request. This would be the largest number of
715 * address/length pairs the host adapter can actually give as once
718 void blk_queue_max_hw_segments(request_queue_t
*q
, unsigned short max_segments
)
722 printk("%s: set to minimum %d\n", __FUNCTION__
, max_segments
);
725 q
->max_hw_segments
= max_segments
;
728 EXPORT_SYMBOL(blk_queue_max_hw_segments
);
731 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
732 * @q: the request queue for the device
733 * @max_size: max size of segment in bytes
736 * Enables a low level driver to set an upper limit on the size of a
739 void blk_queue_max_segment_size(request_queue_t
*q
, unsigned int max_size
)
741 if (max_size
< PAGE_CACHE_SIZE
) {
742 max_size
= PAGE_CACHE_SIZE
;
743 printk("%s: set to minimum %d\n", __FUNCTION__
, max_size
);
746 q
->max_segment_size
= max_size
;
749 EXPORT_SYMBOL(blk_queue_max_segment_size
);
752 * blk_queue_hardsect_size - set hardware sector size for the queue
753 * @q: the request queue for the device
754 * @size: the hardware sector size, in bytes
757 * This should typically be set to the lowest possible sector size
758 * that the hardware can operate on (possible without reverting to
759 * even internal read-modify-write operations). Usually the default
760 * of 512 covers most hardware.
762 void blk_queue_hardsect_size(request_queue_t
*q
, unsigned short size
)
764 q
->hardsect_size
= size
;
767 EXPORT_SYMBOL(blk_queue_hardsect_size
);
770 * Returns the minimum that is _not_ zero, unless both are zero.
772 #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
775 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
776 * @t: the stacking driver (top)
777 * @b: the underlying device (bottom)
779 void blk_queue_stack_limits(request_queue_t
*t
, request_queue_t
*b
)
781 /* zero is "infinity" */
782 t
->max_sectors
= min_not_zero(t
->max_sectors
,b
->max_sectors
);
783 t
->max_hw_sectors
= min_not_zero(t
->max_hw_sectors
,b
->max_hw_sectors
);
785 t
->max_phys_segments
= min(t
->max_phys_segments
,b
->max_phys_segments
);
786 t
->max_hw_segments
= min(t
->max_hw_segments
,b
->max_hw_segments
);
787 t
->max_segment_size
= min(t
->max_segment_size
,b
->max_segment_size
);
788 t
->hardsect_size
= max(t
->hardsect_size
,b
->hardsect_size
);
789 if (!test_bit(QUEUE_FLAG_CLUSTER
, &b
->queue_flags
))
790 clear_bit(QUEUE_FLAG_CLUSTER
, &t
->queue_flags
);
793 EXPORT_SYMBOL(blk_queue_stack_limits
);
796 * blk_queue_segment_boundary - set boundary rules for segment merging
797 * @q: the request queue for the device
798 * @mask: the memory boundary mask
800 void blk_queue_segment_boundary(request_queue_t
*q
, unsigned long mask
)
802 if (mask
< PAGE_CACHE_SIZE
- 1) {
803 mask
= PAGE_CACHE_SIZE
- 1;
804 printk("%s: set to minimum %lx\n", __FUNCTION__
, mask
);
807 q
->seg_boundary_mask
= mask
;
810 EXPORT_SYMBOL(blk_queue_segment_boundary
);
813 * blk_queue_dma_alignment - set dma length and memory alignment
814 * @q: the request queue for the device
815 * @mask: alignment mask
818 * set required memory and length aligment for direct dma transactions.
819 * this is used when buiding direct io requests for the queue.
822 void blk_queue_dma_alignment(request_queue_t
*q
, int mask
)
824 q
->dma_alignment
= mask
;
827 EXPORT_SYMBOL(blk_queue_dma_alignment
);
830 * blk_queue_find_tag - find a request by its tag and queue
831 * @q: The request queue for the device
832 * @tag: The tag of the request
835 * Should be used when a device returns a tag and you want to match
838 * no locks need be held.
840 struct request
*blk_queue_find_tag(request_queue_t
*q
, int tag
)
842 struct blk_queue_tag
*bqt
= q
->queue_tags
;
844 if (unlikely(bqt
== NULL
|| tag
>= bqt
->real_max_depth
))
847 return bqt
->tag_index
[tag
];
850 EXPORT_SYMBOL(blk_queue_find_tag
);
853 * __blk_free_tags - release a given set of tag maintenance info
854 * @bqt: the tag map to free
856 * Tries to free the specified @bqt@. Returns true if it was
857 * actually freed and false if there are still references using it
859 static int __blk_free_tags(struct blk_queue_tag
*bqt
)
863 retval
= atomic_dec_and_test(&bqt
->refcnt
);
866 BUG_ON(!list_empty(&bqt
->busy_list
));
868 kfree(bqt
->tag_index
);
869 bqt
->tag_index
= NULL
;
882 * __blk_queue_free_tags - release tag maintenance info
883 * @q: the request queue for the device
886 * blk_cleanup_queue() will take care of calling this function, if tagging
887 * has been used. So there's no need to call this directly.
889 static void __blk_queue_free_tags(request_queue_t
*q
)
891 struct blk_queue_tag
*bqt
= q
->queue_tags
;
896 __blk_free_tags(bqt
);
898 q
->queue_tags
= NULL
;
899 q
->queue_flags
&= ~(1 << QUEUE_FLAG_QUEUED
);
904 * blk_free_tags - release a given set of tag maintenance info
905 * @bqt: the tag map to free
907 * For externally managed @bqt@ frees the map. Callers of this
908 * function must guarantee to have released all the queues that
909 * might have been using this tag map.
911 void blk_free_tags(struct blk_queue_tag
*bqt
)
913 if (unlikely(!__blk_free_tags(bqt
)))
916 EXPORT_SYMBOL(blk_free_tags
);
919 * blk_queue_free_tags - release tag maintenance info
920 * @q: the request queue for the device
923 * This is used to disabled tagged queuing to a device, yet leave
926 void blk_queue_free_tags(request_queue_t
*q
)
928 clear_bit(QUEUE_FLAG_QUEUED
, &q
->queue_flags
);
931 EXPORT_SYMBOL(blk_queue_free_tags
);
934 init_tag_map(request_queue_t
*q
, struct blk_queue_tag
*tags
, int depth
)
936 struct request
**tag_index
;
937 unsigned long *tag_map
;
940 if (q
&& depth
> q
->nr_requests
* 2) {
941 depth
= q
->nr_requests
* 2;
942 printk(KERN_ERR
"%s: adjusted depth to %d\n",
943 __FUNCTION__
, depth
);
946 tag_index
= kzalloc(depth
* sizeof(struct request
*), GFP_ATOMIC
);
950 nr_ulongs
= ALIGN(depth
, BITS_PER_LONG
) / BITS_PER_LONG
;
951 tag_map
= kzalloc(nr_ulongs
* sizeof(unsigned long), GFP_ATOMIC
);
955 tags
->real_max_depth
= depth
;
956 tags
->max_depth
= depth
;
957 tags
->tag_index
= tag_index
;
958 tags
->tag_map
= tag_map
;
966 static struct blk_queue_tag
*__blk_queue_init_tags(struct request_queue
*q
,
969 struct blk_queue_tag
*tags
;
971 tags
= kmalloc(sizeof(struct blk_queue_tag
), GFP_ATOMIC
);
975 if (init_tag_map(q
, tags
, depth
))
978 INIT_LIST_HEAD(&tags
->busy_list
);
980 atomic_set(&tags
->refcnt
, 1);
988 * blk_init_tags - initialize the tag info for an external tag map
989 * @depth: the maximum queue depth supported
990 * @tags: the tag to use
992 struct blk_queue_tag
*blk_init_tags(int depth
)
994 return __blk_queue_init_tags(NULL
, depth
);
996 EXPORT_SYMBOL(blk_init_tags
);
999 * blk_queue_init_tags - initialize the queue tag info
1000 * @q: the request queue for the device
1001 * @depth: the maximum queue depth supported
1002 * @tags: the tag to use
1004 int blk_queue_init_tags(request_queue_t
*q
, int depth
,
1005 struct blk_queue_tag
*tags
)
1009 BUG_ON(tags
&& q
->queue_tags
&& tags
!= q
->queue_tags
);
1011 if (!tags
&& !q
->queue_tags
) {
1012 tags
= __blk_queue_init_tags(q
, depth
);
1016 } else if (q
->queue_tags
) {
1017 if ((rc
= blk_queue_resize_tags(q
, depth
)))
1019 set_bit(QUEUE_FLAG_QUEUED
, &q
->queue_flags
);
1022 atomic_inc(&tags
->refcnt
);
1025 * assign it, all done
1027 q
->queue_tags
= tags
;
1028 q
->queue_flags
|= (1 << QUEUE_FLAG_QUEUED
);
1035 EXPORT_SYMBOL(blk_queue_init_tags
);
1038 * blk_queue_resize_tags - change the queueing depth
1039 * @q: the request queue for the device
1040 * @new_depth: the new max command queueing depth
1043 * Must be called with the queue lock held.
1045 int blk_queue_resize_tags(request_queue_t
*q
, int new_depth
)
1047 struct blk_queue_tag
*bqt
= q
->queue_tags
;
1048 struct request
**tag_index
;
1049 unsigned long *tag_map
;
1050 int max_depth
, nr_ulongs
;
1056 * if we already have large enough real_max_depth. just
1057 * adjust max_depth. *NOTE* as requests with tag value
1058 * between new_depth and real_max_depth can be in-flight, tag
1059 * map can not be shrunk blindly here.
1061 if (new_depth
<= bqt
->real_max_depth
) {
1062 bqt
->max_depth
= new_depth
;
1067 * Currently cannot replace a shared tag map with a new
1068 * one, so error out if this is the case
1070 if (atomic_read(&bqt
->refcnt
) != 1)
1074 * save the old state info, so we can copy it back
1076 tag_index
= bqt
->tag_index
;
1077 tag_map
= bqt
->tag_map
;
1078 max_depth
= bqt
->real_max_depth
;
1080 if (init_tag_map(q
, bqt
, new_depth
))
1083 memcpy(bqt
->tag_index
, tag_index
, max_depth
* sizeof(struct request
*));
1084 nr_ulongs
= ALIGN(max_depth
, BITS_PER_LONG
) / BITS_PER_LONG
;
1085 memcpy(bqt
->tag_map
, tag_map
, nr_ulongs
* sizeof(unsigned long));
1092 EXPORT_SYMBOL(blk_queue_resize_tags
);
1095 * blk_queue_end_tag - end tag operations for a request
1096 * @q: the request queue for the device
1097 * @rq: the request that has completed
1100 * Typically called when end_that_request_first() returns 0, meaning
1101 * all transfers have been done for a request. It's important to call
1102 * this function before end_that_request_last(), as that will put the
1103 * request back on the free list thus corrupting the internal tag list.
1106 * queue lock must be held.
1108 void blk_queue_end_tag(request_queue_t
*q
, struct request
*rq
)
1110 struct blk_queue_tag
*bqt
= q
->queue_tags
;
1115 if (unlikely(tag
>= bqt
->real_max_depth
))
1117 * This can happen after tag depth has been reduced.
1118 * FIXME: how about a warning or info message here?
1122 if (unlikely(!__test_and_clear_bit(tag
, bqt
->tag_map
))) {
1123 printk(KERN_ERR
"%s: attempt to clear non-busy tag (%d)\n",
1128 list_del_init(&rq
->queuelist
);
1129 rq
->cmd_flags
&= ~REQ_QUEUED
;
1132 if (unlikely(bqt
->tag_index
[tag
] == NULL
))
1133 printk(KERN_ERR
"%s: tag %d is missing\n",
1136 bqt
->tag_index
[tag
] = NULL
;
1140 EXPORT_SYMBOL(blk_queue_end_tag
);
1143 * blk_queue_start_tag - find a free tag and assign it
1144 * @q: the request queue for the device
1145 * @rq: the block request that needs tagging
1148 * This can either be used as a stand-alone helper, or possibly be
1149 * assigned as the queue &prep_rq_fn (in which case &struct request
1150 * automagically gets a tag assigned). Note that this function
1151 * assumes that any type of request can be queued! if this is not
1152 * true for your device, you must check the request type before
1153 * calling this function. The request will also be removed from
1154 * the request queue, so it's the drivers responsibility to readd
1155 * it if it should need to be restarted for some reason.
1158 * queue lock must be held.
1160 int blk_queue_start_tag(request_queue_t
*q
, struct request
*rq
)
1162 struct blk_queue_tag
*bqt
= q
->queue_tags
;
1165 if (unlikely((rq
->cmd_flags
& REQ_QUEUED
))) {
1167 "%s: request %p for device [%s] already tagged %d",
1169 rq
->rq_disk
? rq
->rq_disk
->disk_name
: "?", rq
->tag
);
1173 tag
= find_first_zero_bit(bqt
->tag_map
, bqt
->max_depth
);
1174 if (tag
>= bqt
->max_depth
)
1177 __set_bit(tag
, bqt
->tag_map
);
1179 rq
->cmd_flags
|= REQ_QUEUED
;
1181 bqt
->tag_index
[tag
] = rq
;
1182 blkdev_dequeue_request(rq
);
1183 list_add(&rq
->queuelist
, &bqt
->busy_list
);
1188 EXPORT_SYMBOL(blk_queue_start_tag
);
1191 * blk_queue_invalidate_tags - invalidate all pending tags
1192 * @q: the request queue for the device
1195 * Hardware conditions may dictate a need to stop all pending requests.
1196 * In this case, we will safely clear the block side of the tag queue and
1197 * readd all requests to the request queue in the right order.
1200 * queue lock must be held.
1202 void blk_queue_invalidate_tags(request_queue_t
*q
)
1204 struct blk_queue_tag
*bqt
= q
->queue_tags
;
1205 struct list_head
*tmp
, *n
;
1208 list_for_each_safe(tmp
, n
, &bqt
->busy_list
) {
1209 rq
= list_entry_rq(tmp
);
1211 if (rq
->tag
== -1) {
1213 "%s: bad tag found on list\n", __FUNCTION__
);
1214 list_del_init(&rq
->queuelist
);
1215 rq
->cmd_flags
&= ~REQ_QUEUED
;
1217 blk_queue_end_tag(q
, rq
);
1219 rq
->cmd_flags
&= ~REQ_STARTED
;
1220 __elv_add_request(q
, rq
, ELEVATOR_INSERT_BACK
, 0);
1224 EXPORT_SYMBOL(blk_queue_invalidate_tags
);
1226 void blk_dump_rq_flags(struct request
*rq
, char *msg
)
1230 printk("%s: dev %s: type=%x, flags=%x\n", msg
,
1231 rq
->rq_disk
? rq
->rq_disk
->disk_name
: "?", rq
->cmd_type
,
1234 printk("\nsector %llu, nr/cnr %lu/%u\n", (unsigned long long)rq
->sector
,
1236 rq
->current_nr_sectors
);
1237 printk("bio %p, biotail %p, buffer %p, data %p, len %u\n", rq
->bio
, rq
->biotail
, rq
->buffer
, rq
->data
, rq
->data_len
);
1239 if (blk_pc_request(rq
)) {
1241 for (bit
= 0; bit
< sizeof(rq
->cmd
); bit
++)
1242 printk("%02x ", rq
->cmd
[bit
]);
1247 EXPORT_SYMBOL(blk_dump_rq_flags
);
1249 void blk_recount_segments(request_queue_t
*q
, struct bio
*bio
)
1251 struct bio_vec
*bv
, *bvprv
= NULL
;
1252 int i
, nr_phys_segs
, nr_hw_segs
, seg_size
, hw_seg_size
, cluster
;
1253 int high
, highprv
= 1;
1255 if (unlikely(!bio
->bi_io_vec
))
1258 cluster
= q
->queue_flags
& (1 << QUEUE_FLAG_CLUSTER
);
1259 hw_seg_size
= seg_size
= nr_phys_segs
= nr_hw_segs
= 0;
1260 bio_for_each_segment(bv
, bio
, i
) {
1262 * the trick here is making sure that a high page is never
1263 * considered part of another segment, since that might
1264 * change with the bounce page.
1266 high
= page_to_pfn(bv
->bv_page
) >= q
->bounce_pfn
;
1267 if (high
|| highprv
)
1268 goto new_hw_segment
;
1270 if (seg_size
+ bv
->bv_len
> q
->max_segment_size
)
1272 if (!BIOVEC_PHYS_MERGEABLE(bvprv
, bv
))
1274 if (!BIOVEC_SEG_BOUNDARY(q
, bvprv
, bv
))
1276 if (BIOVEC_VIRT_OVERSIZE(hw_seg_size
+ bv
->bv_len
))
1277 goto new_hw_segment
;
1279 seg_size
+= bv
->bv_len
;
1280 hw_seg_size
+= bv
->bv_len
;
1285 if (BIOVEC_VIRT_MERGEABLE(bvprv
, bv
) &&
1286 !BIOVEC_VIRT_OVERSIZE(hw_seg_size
+ bv
->bv_len
)) {
1287 hw_seg_size
+= bv
->bv_len
;
1290 if (hw_seg_size
> bio
->bi_hw_front_size
)
1291 bio
->bi_hw_front_size
= hw_seg_size
;
1292 hw_seg_size
= BIOVEC_VIRT_START_SIZE(bv
) + bv
->bv_len
;
1298 seg_size
= bv
->bv_len
;
1301 if (hw_seg_size
> bio
->bi_hw_back_size
)
1302 bio
->bi_hw_back_size
= hw_seg_size
;
1303 if (nr_hw_segs
== 1 && hw_seg_size
> bio
->bi_hw_front_size
)
1304 bio
->bi_hw_front_size
= hw_seg_size
;
1305 bio
->bi_phys_segments
= nr_phys_segs
;
1306 bio
->bi_hw_segments
= nr_hw_segs
;
1307 bio
->bi_flags
|= (1 << BIO_SEG_VALID
);
1311 static int blk_phys_contig_segment(request_queue_t
*q
, struct bio
*bio
,
1314 if (!(q
->queue_flags
& (1 << QUEUE_FLAG_CLUSTER
)))
1317 if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio
), __BVEC_START(nxt
)))
1319 if (bio
->bi_size
+ nxt
->bi_size
> q
->max_segment_size
)
1323 * bio and nxt are contigous in memory, check if the queue allows
1324 * these two to be merged into one
1326 if (BIO_SEG_BOUNDARY(q
, bio
, nxt
))
1332 static int blk_hw_contig_segment(request_queue_t
*q
, struct bio
*bio
,
1335 if (unlikely(!bio_flagged(bio
, BIO_SEG_VALID
)))
1336 blk_recount_segments(q
, bio
);
1337 if (unlikely(!bio_flagged(nxt
, BIO_SEG_VALID
)))
1338 blk_recount_segments(q
, nxt
);
1339 if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio
), __BVEC_START(nxt
)) ||
1340 BIOVEC_VIRT_OVERSIZE(bio
->bi_hw_front_size
+ bio
->bi_hw_back_size
))
1342 if (bio
->bi_size
+ nxt
->bi_size
> q
->max_segment_size
)
1349 * map a request to scatterlist, return number of sg entries setup. Caller
1350 * must make sure sg can hold rq->nr_phys_segments entries
1352 int blk_rq_map_sg(request_queue_t
*q
, struct request
*rq
, struct scatterlist
*sg
)
1354 struct bio_vec
*bvec
, *bvprv
;
1356 int nsegs
, i
, cluster
;
1359 cluster
= q
->queue_flags
& (1 << QUEUE_FLAG_CLUSTER
);
1362 * for each bio in rq
1365 rq_for_each_bio(bio
, rq
) {
1367 * for each segment in bio
1369 bio_for_each_segment(bvec
, bio
, i
) {
1370 int nbytes
= bvec
->bv_len
;
1372 if (bvprv
&& cluster
) {
1373 if (sg
[nsegs
- 1].length
+ nbytes
> q
->max_segment_size
)
1376 if (!BIOVEC_PHYS_MERGEABLE(bvprv
, bvec
))
1378 if (!BIOVEC_SEG_BOUNDARY(q
, bvprv
, bvec
))
1381 sg
[nsegs
- 1].length
+= nbytes
;
1384 memset(&sg
[nsegs
],0,sizeof(struct scatterlist
));
1385 sg
[nsegs
].page
= bvec
->bv_page
;
1386 sg
[nsegs
].length
= nbytes
;
1387 sg
[nsegs
].offset
= bvec
->bv_offset
;
1392 } /* segments in bio */
1398 EXPORT_SYMBOL(blk_rq_map_sg
);
1401 * the standard queue merge functions, can be overridden with device
1402 * specific ones if so desired
1405 static inline int ll_new_mergeable(request_queue_t
*q
,
1406 struct request
*req
,
1409 int nr_phys_segs
= bio_phys_segments(q
, bio
);
1411 if (req
->nr_phys_segments
+ nr_phys_segs
> q
->max_phys_segments
) {
1412 req
->cmd_flags
|= REQ_NOMERGE
;
1413 if (req
== q
->last_merge
)
1414 q
->last_merge
= NULL
;
1419 * A hw segment is just getting larger, bump just the phys
1422 req
->nr_phys_segments
+= nr_phys_segs
;
1426 static inline int ll_new_hw_segment(request_queue_t
*q
,
1427 struct request
*req
,
1430 int nr_hw_segs
= bio_hw_segments(q
, bio
);
1431 int nr_phys_segs
= bio_phys_segments(q
, bio
);
1433 if (req
->nr_hw_segments
+ nr_hw_segs
> q
->max_hw_segments
1434 || req
->nr_phys_segments
+ nr_phys_segs
> q
->max_phys_segments
) {
1435 req
->cmd_flags
|= REQ_NOMERGE
;
1436 if (req
== q
->last_merge
)
1437 q
->last_merge
= NULL
;
1442 * This will form the start of a new hw segment. Bump both
1445 req
->nr_hw_segments
+= nr_hw_segs
;
1446 req
->nr_phys_segments
+= nr_phys_segs
;
1450 static int ll_back_merge_fn(request_queue_t
*q
, struct request
*req
,
1453 unsigned short max_sectors
;
1456 if (unlikely(blk_pc_request(req
)))
1457 max_sectors
= q
->max_hw_sectors
;
1459 max_sectors
= q
->max_sectors
;
1461 if (req
->nr_sectors
+ bio_sectors(bio
) > max_sectors
) {
1462 req
->cmd_flags
|= REQ_NOMERGE
;
1463 if (req
== q
->last_merge
)
1464 q
->last_merge
= NULL
;
1467 if (unlikely(!bio_flagged(req
->biotail
, BIO_SEG_VALID
)))
1468 blk_recount_segments(q
, req
->biotail
);
1469 if (unlikely(!bio_flagged(bio
, BIO_SEG_VALID
)))
1470 blk_recount_segments(q
, bio
);
1471 len
= req
->biotail
->bi_hw_back_size
+ bio
->bi_hw_front_size
;
1472 if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req
->biotail
), __BVEC_START(bio
)) &&
1473 !BIOVEC_VIRT_OVERSIZE(len
)) {
1474 int mergeable
= ll_new_mergeable(q
, req
, bio
);
1477 if (req
->nr_hw_segments
== 1)
1478 req
->bio
->bi_hw_front_size
= len
;
1479 if (bio
->bi_hw_segments
== 1)
1480 bio
->bi_hw_back_size
= len
;
1485 return ll_new_hw_segment(q
, req
, bio
);
1488 static int ll_front_merge_fn(request_queue_t
*q
, struct request
*req
,
1491 unsigned short max_sectors
;
1494 if (unlikely(blk_pc_request(req
)))
1495 max_sectors
= q
->max_hw_sectors
;
1497 max_sectors
= q
->max_sectors
;
1500 if (req
->nr_sectors
+ bio_sectors(bio
) > max_sectors
) {
1501 req
->cmd_flags
|= REQ_NOMERGE
;
1502 if (req
== q
->last_merge
)
1503 q
->last_merge
= NULL
;
1506 len
= bio
->bi_hw_back_size
+ req
->bio
->bi_hw_front_size
;
1507 if (unlikely(!bio_flagged(bio
, BIO_SEG_VALID
)))
1508 blk_recount_segments(q
, bio
);
1509 if (unlikely(!bio_flagged(req
->bio
, BIO_SEG_VALID
)))
1510 blk_recount_segments(q
, req
->bio
);
1511 if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio
), __BVEC_START(req
->bio
)) &&
1512 !BIOVEC_VIRT_OVERSIZE(len
)) {
1513 int mergeable
= ll_new_mergeable(q
, req
, bio
);
1516 if (bio
->bi_hw_segments
== 1)
1517 bio
->bi_hw_front_size
= len
;
1518 if (req
->nr_hw_segments
== 1)
1519 req
->biotail
->bi_hw_back_size
= len
;
1524 return ll_new_hw_segment(q
, req
, bio
);
1527 static int ll_merge_requests_fn(request_queue_t
*q
, struct request
*req
,
1528 struct request
*next
)
1530 int total_phys_segments
;
1531 int total_hw_segments
;
1534 * First check if the either of the requests are re-queued
1535 * requests. Can't merge them if they are.
1537 if (req
->special
|| next
->special
)
1541 * Will it become too large?
1543 if ((req
->nr_sectors
+ next
->nr_sectors
) > q
->max_sectors
)
1546 total_phys_segments
= req
->nr_phys_segments
+ next
->nr_phys_segments
;
1547 if (blk_phys_contig_segment(q
, req
->biotail
, next
->bio
))
1548 total_phys_segments
--;
1550 if (total_phys_segments
> q
->max_phys_segments
)
1553 total_hw_segments
= req
->nr_hw_segments
+ next
->nr_hw_segments
;
1554 if (blk_hw_contig_segment(q
, req
->biotail
, next
->bio
)) {
1555 int len
= req
->biotail
->bi_hw_back_size
+ next
->bio
->bi_hw_front_size
;
1557 * propagate the combined length to the end of the requests
1559 if (req
->nr_hw_segments
== 1)
1560 req
->bio
->bi_hw_front_size
= len
;
1561 if (next
->nr_hw_segments
== 1)
1562 next
->biotail
->bi_hw_back_size
= len
;
1563 total_hw_segments
--;
1566 if (total_hw_segments
> q
->max_hw_segments
)
1569 /* Merge is OK... */
1570 req
->nr_phys_segments
= total_phys_segments
;
1571 req
->nr_hw_segments
= total_hw_segments
;
1576 * "plug" the device if there are no outstanding requests: this will
1577 * force the transfer to start only after we have put all the requests
1580 * This is called with interrupts off and no requests on the queue and
1581 * with the queue lock held.
1583 void blk_plug_device(request_queue_t
*q
)
1585 WARN_ON(!irqs_disabled());
1588 * don't plug a stopped queue, it must be paired with blk_start_queue()
1589 * which will restart the queueing
1591 if (blk_queue_stopped(q
))
1594 if (!test_and_set_bit(QUEUE_FLAG_PLUGGED
, &q
->queue_flags
)) {
1595 mod_timer(&q
->unplug_timer
, jiffies
+ q
->unplug_delay
);
1596 blk_add_trace_generic(q
, NULL
, 0, BLK_TA_PLUG
);
1600 EXPORT_SYMBOL(blk_plug_device
);
1603 * remove the queue from the plugged list, if present. called with
1604 * queue lock held and interrupts disabled.
1606 int blk_remove_plug(request_queue_t
*q
)
1608 WARN_ON(!irqs_disabled());
1610 if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED
, &q
->queue_flags
))
1613 del_timer(&q
->unplug_timer
);
1617 EXPORT_SYMBOL(blk_remove_plug
);
1620 * remove the plug and let it rip..
1622 void __generic_unplug_device(request_queue_t
*q
)
1624 if (unlikely(blk_queue_stopped(q
)))
1627 if (!blk_remove_plug(q
))
1632 EXPORT_SYMBOL(__generic_unplug_device
);
1635 * generic_unplug_device - fire a request queue
1636 * @q: The &request_queue_t in question
1639 * Linux uses plugging to build bigger requests queues before letting
1640 * the device have at them. If a queue is plugged, the I/O scheduler
1641 * is still adding and merging requests on the queue. Once the queue
1642 * gets unplugged, the request_fn defined for the queue is invoked and
1643 * transfers started.
1645 void generic_unplug_device(request_queue_t
*q
)
1647 spin_lock_irq(q
->queue_lock
);
1648 __generic_unplug_device(q
);
1649 spin_unlock_irq(q
->queue_lock
);
1651 EXPORT_SYMBOL(generic_unplug_device
);
1653 static void blk_backing_dev_unplug(struct backing_dev_info
*bdi
,
1656 request_queue_t
*q
= bdi
->unplug_io_data
;
1659 * devices don't necessarily have an ->unplug_fn defined
1662 blk_add_trace_pdu_int(q
, BLK_TA_UNPLUG_IO
, NULL
,
1663 q
->rq
.count
[READ
] + q
->rq
.count
[WRITE
]);
1669 static void blk_unplug_work(void *data
)
1671 request_queue_t
*q
= data
;
1673 blk_add_trace_pdu_int(q
, BLK_TA_UNPLUG_IO
, NULL
,
1674 q
->rq
.count
[READ
] + q
->rq
.count
[WRITE
]);
1679 static void blk_unplug_timeout(unsigned long data
)
1681 request_queue_t
*q
= (request_queue_t
*)data
;
1683 blk_add_trace_pdu_int(q
, BLK_TA_UNPLUG_TIMER
, NULL
,
1684 q
->rq
.count
[READ
] + q
->rq
.count
[WRITE
]);
1686 kblockd_schedule_work(&q
->unplug_work
);
1690 * blk_start_queue - restart a previously stopped queue
1691 * @q: The &request_queue_t in question
1694 * blk_start_queue() will clear the stop flag on the queue, and call
1695 * the request_fn for the queue if it was in a stopped state when
1696 * entered. Also see blk_stop_queue(). Queue lock must be held.
1698 void blk_start_queue(request_queue_t
*q
)
1700 WARN_ON(!irqs_disabled());
1702 clear_bit(QUEUE_FLAG_STOPPED
, &q
->queue_flags
);
1705 * one level of recursion is ok and is much faster than kicking
1706 * the unplug handling
1708 if (!test_and_set_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
)) {
1710 clear_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
);
1713 kblockd_schedule_work(&q
->unplug_work
);
1717 EXPORT_SYMBOL(blk_start_queue
);
1720 * blk_stop_queue - stop a queue
1721 * @q: The &request_queue_t in question
1724 * The Linux block layer assumes that a block driver will consume all
1725 * entries on the request queue when the request_fn strategy is called.
1726 * Often this will not happen, because of hardware limitations (queue
1727 * depth settings). If a device driver gets a 'queue full' response,
1728 * or if it simply chooses not to queue more I/O at one point, it can
1729 * call this function to prevent the request_fn from being called until
1730 * the driver has signalled it's ready to go again. This happens by calling
1731 * blk_start_queue() to restart queue operations. Queue lock must be held.
1733 void blk_stop_queue(request_queue_t
*q
)
1736 set_bit(QUEUE_FLAG_STOPPED
, &q
->queue_flags
);
1738 EXPORT_SYMBOL(blk_stop_queue
);
1741 * blk_sync_queue - cancel any pending callbacks on a queue
1745 * The block layer may perform asynchronous callback activity
1746 * on a queue, such as calling the unplug function after a timeout.
1747 * A block device may call blk_sync_queue to ensure that any
1748 * such activity is cancelled, thus allowing it to release resources
1749 * the the callbacks might use. The caller must already have made sure
1750 * that its ->make_request_fn will not re-add plugging prior to calling
1754 void blk_sync_queue(struct request_queue
*q
)
1756 del_timer_sync(&q
->unplug_timer
);
1759 EXPORT_SYMBOL(blk_sync_queue
);
1762 * blk_run_queue - run a single device queue
1763 * @q: The queue to run
1765 void blk_run_queue(struct request_queue
*q
)
1767 unsigned long flags
;
1769 spin_lock_irqsave(q
->queue_lock
, flags
);
1773 * Only recurse once to avoid overrunning the stack, let the unplug
1774 * handling reinvoke the handler shortly if we already got there.
1776 if (!elv_queue_empty(q
)) {
1777 if (!test_and_set_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
)) {
1779 clear_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
);
1782 kblockd_schedule_work(&q
->unplug_work
);
1786 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1788 EXPORT_SYMBOL(blk_run_queue
);
1791 * blk_cleanup_queue: - release a &request_queue_t when it is no longer needed
1792 * @kobj: the kobj belonging of the request queue to be released
1795 * blk_cleanup_queue is the pair to blk_init_queue() or
1796 * blk_queue_make_request(). It should be called when a request queue is
1797 * being released; typically when a block device is being de-registered.
1798 * Currently, its primary task it to free all the &struct request
1799 * structures that were allocated to the queue and the queue itself.
1802 * Hopefully the low level driver will have finished any
1803 * outstanding requests first...
1805 static void blk_release_queue(struct kobject
*kobj
)
1807 request_queue_t
*q
= container_of(kobj
, struct request_queue
, kobj
);
1808 struct request_list
*rl
= &q
->rq
;
1813 mempool_destroy(rl
->rq_pool
);
1816 __blk_queue_free_tags(q
);
1818 blk_trace_shutdown(q
);
1820 kmem_cache_free(requestq_cachep
, q
);
1823 void blk_put_queue(request_queue_t
*q
)
1825 kobject_put(&q
->kobj
);
1827 EXPORT_SYMBOL(blk_put_queue
);
1829 void blk_cleanup_queue(request_queue_t
* q
)
1831 mutex_lock(&q
->sysfs_lock
);
1832 set_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
);
1833 mutex_unlock(&q
->sysfs_lock
);
1836 elevator_exit(q
->elevator
);
1841 EXPORT_SYMBOL(blk_cleanup_queue
);
1843 static int blk_init_free_list(request_queue_t
*q
)
1845 struct request_list
*rl
= &q
->rq
;
1847 rl
->count
[READ
] = rl
->count
[WRITE
] = 0;
1848 rl
->starved
[READ
] = rl
->starved
[WRITE
] = 0;
1850 init_waitqueue_head(&rl
->wait
[READ
]);
1851 init_waitqueue_head(&rl
->wait
[WRITE
]);
1853 rl
->rq_pool
= mempool_create_node(BLKDEV_MIN_RQ
, mempool_alloc_slab
,
1854 mempool_free_slab
, request_cachep
, q
->node
);
1862 request_queue_t
*blk_alloc_queue(gfp_t gfp_mask
)
1864 return blk_alloc_queue_node(gfp_mask
, -1);
1866 EXPORT_SYMBOL(blk_alloc_queue
);
1868 static struct kobj_type queue_ktype
;
1870 request_queue_t
*blk_alloc_queue_node(gfp_t gfp_mask
, int node_id
)
1874 q
= kmem_cache_alloc_node(requestq_cachep
, gfp_mask
, node_id
);
1878 memset(q
, 0, sizeof(*q
));
1879 init_timer(&q
->unplug_timer
);
1881 snprintf(q
->kobj
.name
, KOBJ_NAME_LEN
, "%s", "queue");
1882 q
->kobj
.ktype
= &queue_ktype
;
1883 kobject_init(&q
->kobj
);
1885 q
->backing_dev_info
.unplug_io_fn
= blk_backing_dev_unplug
;
1886 q
->backing_dev_info
.unplug_io_data
= q
;
1888 mutex_init(&q
->sysfs_lock
);
1892 EXPORT_SYMBOL(blk_alloc_queue_node
);
1895 * blk_init_queue - prepare a request queue for use with a block device
1896 * @rfn: The function to be called to process requests that have been
1897 * placed on the queue.
1898 * @lock: Request queue spin lock
1901 * If a block device wishes to use the standard request handling procedures,
1902 * which sorts requests and coalesces adjacent requests, then it must
1903 * call blk_init_queue(). The function @rfn will be called when there
1904 * are requests on the queue that need to be processed. If the device
1905 * supports plugging, then @rfn may not be called immediately when requests
1906 * are available on the queue, but may be called at some time later instead.
1907 * Plugged queues are generally unplugged when a buffer belonging to one
1908 * of the requests on the queue is needed, or due to memory pressure.
1910 * @rfn is not required, or even expected, to remove all requests off the
1911 * queue, but only as many as it can handle at a time. If it does leave
1912 * requests on the queue, it is responsible for arranging that the requests
1913 * get dealt with eventually.
1915 * The queue spin lock must be held while manipulating the requests on the
1916 * request queue; this lock will be taken also from interrupt context, so irq
1917 * disabling is needed for it.
1919 * Function returns a pointer to the initialized request queue, or NULL if
1920 * it didn't succeed.
1923 * blk_init_queue() must be paired with a blk_cleanup_queue() call
1924 * when the block device is deactivated (such as at module unload).
1927 request_queue_t
*blk_init_queue(request_fn_proc
*rfn
, spinlock_t
*lock
)
1929 return blk_init_queue_node(rfn
, lock
, -1);
1931 EXPORT_SYMBOL(blk_init_queue
);
1934 blk_init_queue_node(request_fn_proc
*rfn
, spinlock_t
*lock
, int node_id
)
1936 request_queue_t
*q
= blk_alloc_queue_node(GFP_KERNEL
, node_id
);
1942 if (blk_init_free_list(q
)) {
1943 kmem_cache_free(requestq_cachep
, q
);
1948 * if caller didn't supply a lock, they get per-queue locking with
1952 spin_lock_init(&q
->__queue_lock
);
1953 lock
= &q
->__queue_lock
;
1956 q
->request_fn
= rfn
;
1957 q
->back_merge_fn
= ll_back_merge_fn
;
1958 q
->front_merge_fn
= ll_front_merge_fn
;
1959 q
->merge_requests_fn
= ll_merge_requests_fn
;
1960 q
->prep_rq_fn
= NULL
;
1961 q
->unplug_fn
= generic_unplug_device
;
1962 q
->queue_flags
= (1 << QUEUE_FLAG_CLUSTER
);
1963 q
->queue_lock
= lock
;
1965 blk_queue_segment_boundary(q
, 0xffffffff);
1967 blk_queue_make_request(q
, __make_request
);
1968 blk_queue_max_segment_size(q
, MAX_SEGMENT_SIZE
);
1970 blk_queue_max_hw_segments(q
, MAX_HW_SEGMENTS
);
1971 blk_queue_max_phys_segments(q
, MAX_PHYS_SEGMENTS
);
1976 if (!elevator_init(q
, NULL
)) {
1977 blk_queue_congestion_threshold(q
);
1984 EXPORT_SYMBOL(blk_init_queue_node
);
1986 int blk_get_queue(request_queue_t
*q
)
1988 if (likely(!test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
))) {
1989 kobject_get(&q
->kobj
);
1996 EXPORT_SYMBOL(blk_get_queue
);
1998 static inline void blk_free_request(request_queue_t
*q
, struct request
*rq
)
2000 if (rq
->cmd_flags
& REQ_ELVPRIV
)
2001 elv_put_request(q
, rq
);
2002 mempool_free(rq
, q
->rq
.rq_pool
);
2005 static inline struct request
*
2006 blk_alloc_request(request_queue_t
*q
, int rw
, int priv
, gfp_t gfp_mask
)
2008 struct request
*rq
= mempool_alloc(q
->rq
.rq_pool
, gfp_mask
);
2014 * first three bits are identical in rq->cmd_flags and bio->bi_rw,
2015 * see bio.h and blkdev.h
2017 rq
->cmd_flags
= rw
| REQ_ALLOCED
;
2020 if (unlikely(elv_set_request(q
, rq
, gfp_mask
))) {
2021 mempool_free(rq
, q
->rq
.rq_pool
);
2024 rq
->cmd_flags
|= REQ_ELVPRIV
;
2031 * ioc_batching returns true if the ioc is a valid batching request and
2032 * should be given priority access to a request.
2034 static inline int ioc_batching(request_queue_t
*q
, struct io_context
*ioc
)
2040 * Make sure the process is able to allocate at least 1 request
2041 * even if the batch times out, otherwise we could theoretically
2044 return ioc
->nr_batch_requests
== q
->nr_batching
||
2045 (ioc
->nr_batch_requests
> 0
2046 && time_before(jiffies
, ioc
->last_waited
+ BLK_BATCH_TIME
));
2050 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
2051 * will cause the process to be a "batcher" on all queues in the system. This
2052 * is the behaviour we want though - once it gets a wakeup it should be given
2055 static void ioc_set_batching(request_queue_t
*q
, struct io_context
*ioc
)
2057 if (!ioc
|| ioc_batching(q
, ioc
))
2060 ioc
->nr_batch_requests
= q
->nr_batching
;
2061 ioc
->last_waited
= jiffies
;
2064 static void __freed_request(request_queue_t
*q
, int rw
)
2066 struct request_list
*rl
= &q
->rq
;
2068 if (rl
->count
[rw
] < queue_congestion_off_threshold(q
))
2069 clear_queue_congested(q
, rw
);
2071 if (rl
->count
[rw
] + 1 <= q
->nr_requests
) {
2072 if (waitqueue_active(&rl
->wait
[rw
]))
2073 wake_up(&rl
->wait
[rw
]);
2075 blk_clear_queue_full(q
, rw
);
2080 * A request has just been released. Account for it, update the full and
2081 * congestion status, wake up any waiters. Called under q->queue_lock.
2083 static void freed_request(request_queue_t
*q
, int rw
, int priv
)
2085 struct request_list
*rl
= &q
->rq
;
2091 __freed_request(q
, rw
);
2093 if (unlikely(rl
->starved
[rw
^ 1]))
2094 __freed_request(q
, rw
^ 1);
2097 #define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist)
2099 * Get a free request, queue_lock must be held.
2100 * Returns NULL on failure, with queue_lock held.
2101 * Returns !NULL on success, with queue_lock *not held*.
2103 static struct request
*get_request(request_queue_t
*q
, int rw
, struct bio
*bio
,
2106 struct request
*rq
= NULL
;
2107 struct request_list
*rl
= &q
->rq
;
2108 struct io_context
*ioc
= NULL
;
2109 int may_queue
, priv
;
2111 may_queue
= elv_may_queue(q
, rw
);
2112 if (may_queue
== ELV_MQUEUE_NO
)
2115 if (rl
->count
[rw
]+1 >= queue_congestion_on_threshold(q
)) {
2116 if (rl
->count
[rw
]+1 >= q
->nr_requests
) {
2117 ioc
= current_io_context(GFP_ATOMIC
);
2119 * The queue will fill after this allocation, so set
2120 * it as full, and mark this process as "batching".
2121 * This process will be allowed to complete a batch of
2122 * requests, others will be blocked.
2124 if (!blk_queue_full(q
, rw
)) {
2125 ioc_set_batching(q
, ioc
);
2126 blk_set_queue_full(q
, rw
);
2128 if (may_queue
!= ELV_MQUEUE_MUST
2129 && !ioc_batching(q
, ioc
)) {
2131 * The queue is full and the allocating
2132 * process is not a "batcher", and not
2133 * exempted by the IO scheduler
2139 set_queue_congested(q
, rw
);
2143 * Only allow batching queuers to allocate up to 50% over the defined
2144 * limit of requests, otherwise we could have thousands of requests
2145 * allocated with any setting of ->nr_requests
2147 if (rl
->count
[rw
] >= (3 * q
->nr_requests
/ 2))
2151 rl
->starved
[rw
] = 0;
2153 priv
= !test_bit(QUEUE_FLAG_ELVSWITCH
, &q
->queue_flags
);
2157 spin_unlock_irq(q
->queue_lock
);
2159 rq
= blk_alloc_request(q
, rw
, priv
, gfp_mask
);
2160 if (unlikely(!rq
)) {
2162 * Allocation failed presumably due to memory. Undo anything
2163 * we might have messed up.
2165 * Allocating task should really be put onto the front of the
2166 * wait queue, but this is pretty rare.
2168 spin_lock_irq(q
->queue_lock
);
2169 freed_request(q
, rw
, priv
);
2172 * in the very unlikely event that allocation failed and no
2173 * requests for this direction was pending, mark us starved
2174 * so that freeing of a request in the other direction will
2175 * notice us. another possible fix would be to split the
2176 * rq mempool into READ and WRITE
2179 if (unlikely(rl
->count
[rw
] == 0))
2180 rl
->starved
[rw
] = 1;
2186 * ioc may be NULL here, and ioc_batching will be false. That's
2187 * OK, if the queue is under the request limit then requests need
2188 * not count toward the nr_batch_requests limit. There will always
2189 * be some limit enforced by BLK_BATCH_TIME.
2191 if (ioc_batching(q
, ioc
))
2192 ioc
->nr_batch_requests
--;
2196 blk_add_trace_generic(q
, bio
, rw
, BLK_TA_GETRQ
);
2202 * No available requests for this queue, unplug the device and wait for some
2203 * requests to become available.
2205 * Called with q->queue_lock held, and returns with it unlocked.
2207 static struct request
*get_request_wait(request_queue_t
*q
, int rw
,
2212 rq
= get_request(q
, rw
, bio
, GFP_NOIO
);
2215 struct request_list
*rl
= &q
->rq
;
2217 prepare_to_wait_exclusive(&rl
->wait
[rw
], &wait
,
2218 TASK_UNINTERRUPTIBLE
);
2220 rq
= get_request(q
, rw
, bio
, GFP_NOIO
);
2223 struct io_context
*ioc
;
2225 blk_add_trace_generic(q
, bio
, rw
, BLK_TA_SLEEPRQ
);
2227 __generic_unplug_device(q
);
2228 spin_unlock_irq(q
->queue_lock
);
2232 * After sleeping, we become a "batching" process and
2233 * will be able to allocate at least one request, and
2234 * up to a big batch of them for a small period time.
2235 * See ioc_batching, ioc_set_batching
2237 ioc
= current_io_context(GFP_NOIO
);
2238 ioc_set_batching(q
, ioc
);
2240 spin_lock_irq(q
->queue_lock
);
2242 finish_wait(&rl
->wait
[rw
], &wait
);
2248 struct request
*blk_get_request(request_queue_t
*q
, int rw
, gfp_t gfp_mask
)
2252 BUG_ON(rw
!= READ
&& rw
!= WRITE
);
2254 spin_lock_irq(q
->queue_lock
);
2255 if (gfp_mask
& __GFP_WAIT
) {
2256 rq
= get_request_wait(q
, rw
, NULL
);
2258 rq
= get_request(q
, rw
, NULL
, gfp_mask
);
2260 spin_unlock_irq(q
->queue_lock
);
2262 /* q->queue_lock is unlocked at this point */
2266 EXPORT_SYMBOL(blk_get_request
);
2269 * blk_requeue_request - put a request back on queue
2270 * @q: request queue where request should be inserted
2271 * @rq: request to be inserted
2274 * Drivers often keep queueing requests until the hardware cannot accept
2275 * more, when that condition happens we need to put the request back
2276 * on the queue. Must be called with queue lock held.
2278 void blk_requeue_request(request_queue_t
*q
, struct request
*rq
)
2280 blk_add_trace_rq(q
, rq
, BLK_TA_REQUEUE
);
2282 if (blk_rq_tagged(rq
))
2283 blk_queue_end_tag(q
, rq
);
2285 elv_requeue_request(q
, rq
);
2288 EXPORT_SYMBOL(blk_requeue_request
);
2291 * blk_insert_request - insert a special request in to a request queue
2292 * @q: request queue where request should be inserted
2293 * @rq: request to be inserted
2294 * @at_head: insert request at head or tail of queue
2295 * @data: private data
2298 * Many block devices need to execute commands asynchronously, so they don't
2299 * block the whole kernel from preemption during request execution. This is
2300 * accomplished normally by inserting aritficial requests tagged as
2301 * REQ_SPECIAL in to the corresponding request queue, and letting them be
2302 * scheduled for actual execution by the request queue.
2304 * We have the option of inserting the head or the tail of the queue.
2305 * Typically we use the tail for new ioctls and so forth. We use the head
2306 * of the queue for things like a QUEUE_FULL message from a device, or a
2307 * host that is unable to accept a particular command.
2309 void blk_insert_request(request_queue_t
*q
, struct request
*rq
,
2310 int at_head
, void *data
)
2312 int where
= at_head
? ELEVATOR_INSERT_FRONT
: ELEVATOR_INSERT_BACK
;
2313 unsigned long flags
;
2316 * tell I/O scheduler that this isn't a regular read/write (ie it
2317 * must not attempt merges on this) and that it acts as a soft
2320 rq
->cmd_type
= REQ_TYPE_SPECIAL
;
2321 rq
->cmd_flags
|= REQ_SOFTBARRIER
;
2325 spin_lock_irqsave(q
->queue_lock
, flags
);
2328 * If command is tagged, release the tag
2330 if (blk_rq_tagged(rq
))
2331 blk_queue_end_tag(q
, rq
);
2333 drive_stat_acct(rq
, rq
->nr_sectors
, 1);
2334 __elv_add_request(q
, rq
, where
, 0);
2336 if (blk_queue_plugged(q
))
2337 __generic_unplug_device(q
);
2340 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2343 EXPORT_SYMBOL(blk_insert_request
);
2346 * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
2347 * @q: request queue where request should be inserted
2348 * @rq: request structure to fill
2349 * @ubuf: the user buffer
2350 * @len: length of user data
2353 * Data will be mapped directly for zero copy io, if possible. Otherwise
2354 * a kernel bounce buffer is used.
2356 * A matching blk_rq_unmap_user() must be issued at the end of io, while
2357 * still in process context.
2359 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
2360 * before being submitted to the device, as pages mapped may be out of
2361 * reach. It's the callers responsibility to make sure this happens. The
2362 * original bio must be passed back in to blk_rq_unmap_user() for proper
2365 int blk_rq_map_user(request_queue_t
*q
, struct request
*rq
, void __user
*ubuf
,
2368 unsigned long uaddr
;
2372 if (len
> (q
->max_hw_sectors
<< 9))
2377 reading
= rq_data_dir(rq
) == READ
;
2380 * if alignment requirement is satisfied, map in user pages for
2381 * direct dma. else, set up kernel bounce buffers
2383 uaddr
= (unsigned long) ubuf
;
2384 if (!(uaddr
& queue_dma_alignment(q
)) && !(len
& queue_dma_alignment(q
)))
2385 bio
= bio_map_user(q
, NULL
, uaddr
, len
, reading
);
2387 bio
= bio_copy_user(q
, uaddr
, len
, reading
);
2390 rq
->bio
= rq
->biotail
= bio
;
2391 blk_rq_bio_prep(q
, rq
, bio
);
2393 rq
->buffer
= rq
->data
= NULL
;
2399 * bio is the err-ptr
2401 return PTR_ERR(bio
);
2404 EXPORT_SYMBOL(blk_rq_map_user
);
2407 * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage
2408 * @q: request queue where request should be inserted
2409 * @rq: request to map data to
2410 * @iov: pointer to the iovec
2411 * @iov_count: number of elements in the iovec
2414 * Data will be mapped directly for zero copy io, if possible. Otherwise
2415 * a kernel bounce buffer is used.
2417 * A matching blk_rq_unmap_user() must be issued at the end of io, while
2418 * still in process context.
2420 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
2421 * before being submitted to the device, as pages mapped may be out of
2422 * reach. It's the callers responsibility to make sure this happens. The
2423 * original bio must be passed back in to blk_rq_unmap_user() for proper
2426 int blk_rq_map_user_iov(request_queue_t
*q
, struct request
*rq
,
2427 struct sg_iovec
*iov
, int iov_count
)
2431 if (!iov
|| iov_count
<= 0)
2434 /* we don't allow misaligned data like bio_map_user() does. If the
2435 * user is using sg, they're expected to know the alignment constraints
2436 * and respect them accordingly */
2437 bio
= bio_map_user_iov(q
, NULL
, iov
, iov_count
, rq_data_dir(rq
)== READ
);
2439 return PTR_ERR(bio
);
2441 rq
->bio
= rq
->biotail
= bio
;
2442 blk_rq_bio_prep(q
, rq
, bio
);
2443 rq
->buffer
= rq
->data
= NULL
;
2444 rq
->data_len
= bio
->bi_size
;
2448 EXPORT_SYMBOL(blk_rq_map_user_iov
);
2451 * blk_rq_unmap_user - unmap a request with user data
2452 * @bio: bio to be unmapped
2453 * @ulen: length of user buffer
2456 * Unmap a bio previously mapped by blk_rq_map_user().
2458 int blk_rq_unmap_user(struct bio
*bio
, unsigned int ulen
)
2463 if (bio_flagged(bio
, BIO_USER_MAPPED
))
2464 bio_unmap_user(bio
);
2466 ret
= bio_uncopy_user(bio
);
2472 EXPORT_SYMBOL(blk_rq_unmap_user
);
2475 * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage
2476 * @q: request queue where request should be inserted
2477 * @rq: request to fill
2478 * @kbuf: the kernel buffer
2479 * @len: length of user data
2480 * @gfp_mask: memory allocation flags
2482 int blk_rq_map_kern(request_queue_t
*q
, struct request
*rq
, void *kbuf
,
2483 unsigned int len
, gfp_t gfp_mask
)
2487 if (len
> (q
->max_hw_sectors
<< 9))
2492 bio
= bio_map_kern(q
, kbuf
, len
, gfp_mask
);
2494 return PTR_ERR(bio
);
2496 if (rq_data_dir(rq
) == WRITE
)
2497 bio
->bi_rw
|= (1 << BIO_RW
);
2499 rq
->bio
= rq
->biotail
= bio
;
2500 blk_rq_bio_prep(q
, rq
, bio
);
2502 rq
->buffer
= rq
->data
= NULL
;
2507 EXPORT_SYMBOL(blk_rq_map_kern
);
2510 * blk_execute_rq_nowait - insert a request into queue for execution
2511 * @q: queue to insert the request in
2512 * @bd_disk: matching gendisk
2513 * @rq: request to insert
2514 * @at_head: insert request at head or tail of queue
2515 * @done: I/O completion handler
2518 * Insert a fully prepared request at the back of the io scheduler queue
2519 * for execution. Don't wait for completion.
2521 void blk_execute_rq_nowait(request_queue_t
*q
, struct gendisk
*bd_disk
,
2522 struct request
*rq
, int at_head
,
2525 int where
= at_head
? ELEVATOR_INSERT_FRONT
: ELEVATOR_INSERT_BACK
;
2527 rq
->rq_disk
= bd_disk
;
2528 rq
->cmd_flags
|= REQ_NOMERGE
;
2530 WARN_ON(irqs_disabled());
2531 spin_lock_irq(q
->queue_lock
);
2532 __elv_add_request(q
, rq
, where
, 1);
2533 __generic_unplug_device(q
);
2534 spin_unlock_irq(q
->queue_lock
);
2536 EXPORT_SYMBOL_GPL(blk_execute_rq_nowait
);
2539 * blk_execute_rq - insert a request into queue for execution
2540 * @q: queue to insert the request in
2541 * @bd_disk: matching gendisk
2542 * @rq: request to insert
2543 * @at_head: insert request at head or tail of queue
2546 * Insert a fully prepared request at the back of the io scheduler queue
2547 * for execution and wait for completion.
2549 int blk_execute_rq(request_queue_t
*q
, struct gendisk
*bd_disk
,
2550 struct request
*rq
, int at_head
)
2552 DECLARE_COMPLETION_ONSTACK(wait
);
2553 char sense
[SCSI_SENSE_BUFFERSIZE
];
2557 * we need an extra reference to the request, so we can look at
2558 * it after io completion
2563 memset(sense
, 0, sizeof(sense
));
2568 rq
->end_io_data
= &wait
;
2569 blk_execute_rq_nowait(q
, bd_disk
, rq
, at_head
, blk_end_sync_rq
);
2570 wait_for_completion(&wait
);
2578 EXPORT_SYMBOL(blk_execute_rq
);
2581 * blkdev_issue_flush - queue a flush
2582 * @bdev: blockdev to issue flush for
2583 * @error_sector: error sector
2586 * Issue a flush for the block device in question. Caller can supply
2587 * room for storing the error offset in case of a flush error, if they
2588 * wish to. Caller must run wait_for_completion() on its own.
2590 int blkdev_issue_flush(struct block_device
*bdev
, sector_t
*error_sector
)
2594 if (bdev
->bd_disk
== NULL
)
2597 q
= bdev_get_queue(bdev
);
2600 if (!q
->issue_flush_fn
)
2603 return q
->issue_flush_fn(q
, bdev
->bd_disk
, error_sector
);
2606 EXPORT_SYMBOL(blkdev_issue_flush
);
2608 static void drive_stat_acct(struct request
*rq
, int nr_sectors
, int new_io
)
2610 int rw
= rq_data_dir(rq
);
2612 if (!blk_fs_request(rq
) || !rq
->rq_disk
)
2616 __disk_stat_inc(rq
->rq_disk
, merges
[rw
]);
2618 disk_round_stats(rq
->rq_disk
);
2619 rq
->rq_disk
->in_flight
++;
2624 * add-request adds a request to the linked list.
2625 * queue lock is held and interrupts disabled, as we muck with the
2626 * request queue list.
2628 static inline void add_request(request_queue_t
* q
, struct request
* req
)
2630 drive_stat_acct(req
, req
->nr_sectors
, 1);
2633 q
->activity_fn(q
->activity_data
, rq_data_dir(req
));
2636 * elevator indicated where it wants this request to be
2637 * inserted at elevator_merge time
2639 __elv_add_request(q
, req
, ELEVATOR_INSERT_SORT
, 0);
2643 * disk_round_stats() - Round off the performance stats on a struct
2646 * The average IO queue length and utilisation statistics are maintained
2647 * by observing the current state of the queue length and the amount of
2648 * time it has been in this state for.
2650 * Normally, that accounting is done on IO completion, but that can result
2651 * in more than a second's worth of IO being accounted for within any one
2652 * second, leading to >100% utilisation. To deal with that, we call this
2653 * function to do a round-off before returning the results when reading
2654 * /proc/diskstats. This accounts immediately for all queue usage up to
2655 * the current jiffies and restarts the counters again.
2657 void disk_round_stats(struct gendisk
*disk
)
2659 unsigned long now
= jiffies
;
2661 if (now
== disk
->stamp
)
2664 if (disk
->in_flight
) {
2665 __disk_stat_add(disk
, time_in_queue
,
2666 disk
->in_flight
* (now
- disk
->stamp
));
2667 __disk_stat_add(disk
, io_ticks
, (now
- disk
->stamp
));
2672 EXPORT_SYMBOL_GPL(disk_round_stats
);
2675 * queue lock must be held
2677 void __blk_put_request(request_queue_t
*q
, struct request
*req
)
2681 if (unlikely(--req
->ref_count
))
2684 elv_completed_request(q
, req
);
2687 * Request may not have originated from ll_rw_blk. if not,
2688 * it didn't come out of our reserved rq pools
2690 if (req
->cmd_flags
& REQ_ALLOCED
) {
2691 int rw
= rq_data_dir(req
);
2692 int priv
= req
->cmd_flags
& REQ_ELVPRIV
;
2694 BUG_ON(!list_empty(&req
->queuelist
));
2695 BUG_ON(!hlist_unhashed(&req
->hash
));
2697 blk_free_request(q
, req
);
2698 freed_request(q
, rw
, priv
);
2702 EXPORT_SYMBOL_GPL(__blk_put_request
);
2704 void blk_put_request(struct request
*req
)
2706 unsigned long flags
;
2707 request_queue_t
*q
= req
->q
;
2710 * Gee, IDE calls in w/ NULL q. Fix IDE and remove the
2711 * following if (q) test.
2714 spin_lock_irqsave(q
->queue_lock
, flags
);
2715 __blk_put_request(q
, req
);
2716 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2720 EXPORT_SYMBOL(blk_put_request
);
2723 * blk_end_sync_rq - executes a completion event on a request
2724 * @rq: request to complete
2725 * @error: end io status of the request
2727 void blk_end_sync_rq(struct request
*rq
, int error
)
2729 struct completion
*waiting
= rq
->end_io_data
;
2731 rq
->end_io_data
= NULL
;
2732 __blk_put_request(rq
->q
, rq
);
2735 * complete last, if this is a stack request the process (and thus
2736 * the rq pointer) could be invalid right after this complete()
2740 EXPORT_SYMBOL(blk_end_sync_rq
);
2743 * blk_congestion_wait - wait for a queue to become uncongested
2744 * @rw: READ or WRITE
2745 * @timeout: timeout in jiffies
2747 * Waits for up to @timeout jiffies for a queue (any queue) to exit congestion.
2748 * If no queues are congested then just wait for the next request to be
2751 long blk_congestion_wait(int rw
, long timeout
)
2755 wait_queue_head_t
*wqh
= &congestion_wqh
[rw
];
2757 prepare_to_wait(wqh
, &wait
, TASK_UNINTERRUPTIBLE
);
2758 ret
= io_schedule_timeout(timeout
);
2759 finish_wait(wqh
, &wait
);
2763 EXPORT_SYMBOL(blk_congestion_wait
);
2766 * blk_congestion_end - wake up sleepers on a congestion queue
2767 * @rw: READ or WRITE
2769 void blk_congestion_end(int rw
)
2771 wait_queue_head_t
*wqh
= &congestion_wqh
[rw
];
2773 if (waitqueue_active(wqh
))
2778 * Has to be called with the request spinlock acquired
2780 static int attempt_merge(request_queue_t
*q
, struct request
*req
,
2781 struct request
*next
)
2783 if (!rq_mergeable(req
) || !rq_mergeable(next
))
2789 if (req
->sector
+ req
->nr_sectors
!= next
->sector
)
2792 if (rq_data_dir(req
) != rq_data_dir(next
)
2793 || req
->rq_disk
!= next
->rq_disk
2798 * If we are allowed to merge, then append bio list
2799 * from next to rq and release next. merge_requests_fn
2800 * will have updated segment counts, update sector
2803 if (!q
->merge_requests_fn(q
, req
, next
))
2807 * At this point we have either done a back merge
2808 * or front merge. We need the smaller start_time of
2809 * the merged requests to be the current request
2810 * for accounting purposes.
2812 if (time_after(req
->start_time
, next
->start_time
))
2813 req
->start_time
= next
->start_time
;
2815 req
->biotail
->bi_next
= next
->bio
;
2816 req
->biotail
= next
->biotail
;
2818 req
->nr_sectors
= req
->hard_nr_sectors
+= next
->hard_nr_sectors
;
2820 elv_merge_requests(q
, req
, next
);
2823 disk_round_stats(req
->rq_disk
);
2824 req
->rq_disk
->in_flight
--;
2827 req
->ioprio
= ioprio_best(req
->ioprio
, next
->ioprio
);
2829 __blk_put_request(q
, next
);
2833 static inline int attempt_back_merge(request_queue_t
*q
, struct request
*rq
)
2835 struct request
*next
= elv_latter_request(q
, rq
);
2838 return attempt_merge(q
, rq
, next
);
2843 static inline int attempt_front_merge(request_queue_t
*q
, struct request
*rq
)
2845 struct request
*prev
= elv_former_request(q
, rq
);
2848 return attempt_merge(q
, prev
, rq
);
2853 static void init_request_from_bio(struct request
*req
, struct bio
*bio
)
2855 req
->cmd_type
= REQ_TYPE_FS
;
2858 * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
2860 if (bio_rw_ahead(bio
) || bio_failfast(bio
))
2861 req
->cmd_flags
|= REQ_FAILFAST
;
2864 * REQ_BARRIER implies no merging, but lets make it explicit
2866 if (unlikely(bio_barrier(bio
)))
2867 req
->cmd_flags
|= (REQ_HARDBARRIER
| REQ_NOMERGE
);
2870 req
->cmd_flags
|= REQ_RW_SYNC
;
2873 req
->hard_sector
= req
->sector
= bio
->bi_sector
;
2874 req
->hard_nr_sectors
= req
->nr_sectors
= bio_sectors(bio
);
2875 req
->current_nr_sectors
= req
->hard_cur_sectors
= bio_cur_sectors(bio
);
2876 req
->nr_phys_segments
= bio_phys_segments(req
->q
, bio
);
2877 req
->nr_hw_segments
= bio_hw_segments(req
->q
, bio
);
2878 req
->buffer
= bio_data(bio
); /* see ->buffer comment above */
2879 req
->bio
= req
->biotail
= bio
;
2880 req
->ioprio
= bio_prio(bio
);
2881 req
->rq_disk
= bio
->bi_bdev
->bd_disk
;
2882 req
->start_time
= jiffies
;
2885 static int __make_request(request_queue_t
*q
, struct bio
*bio
)
2887 struct request
*req
;
2888 int el_ret
, rw
, nr_sectors
, cur_nr_sectors
, barrier
, err
, sync
;
2889 unsigned short prio
;
2892 sector
= bio
->bi_sector
;
2893 nr_sectors
= bio_sectors(bio
);
2894 cur_nr_sectors
= bio_cur_sectors(bio
);
2895 prio
= bio_prio(bio
);
2897 rw
= bio_data_dir(bio
);
2898 sync
= bio_sync(bio
);
2901 * low level driver can indicate that it wants pages above a
2902 * certain limit bounced to low memory (ie for highmem, or even
2903 * ISA dma in theory)
2905 blk_queue_bounce(q
, &bio
);
2907 spin_lock_prefetch(q
->queue_lock
);
2909 barrier
= bio_barrier(bio
);
2910 if (unlikely(barrier
) && (q
->next_ordered
== QUEUE_ORDERED_NONE
)) {
2915 spin_lock_irq(q
->queue_lock
);
2917 if (unlikely(barrier
) || elv_queue_empty(q
))
2920 el_ret
= elv_merge(q
, &req
, bio
);
2922 case ELEVATOR_BACK_MERGE
:
2923 BUG_ON(!rq_mergeable(req
));
2925 if (!q
->back_merge_fn(q
, req
, bio
))
2928 blk_add_trace_bio(q
, bio
, BLK_TA_BACKMERGE
);
2930 req
->biotail
->bi_next
= bio
;
2932 req
->nr_sectors
= req
->hard_nr_sectors
+= nr_sectors
;
2933 req
->ioprio
= ioprio_best(req
->ioprio
, prio
);
2934 drive_stat_acct(req
, nr_sectors
, 0);
2935 if (!attempt_back_merge(q
, req
))
2936 elv_merged_request(q
, req
, el_ret
);
2939 case ELEVATOR_FRONT_MERGE
:
2940 BUG_ON(!rq_mergeable(req
));
2942 if (!q
->front_merge_fn(q
, req
, bio
))
2945 blk_add_trace_bio(q
, bio
, BLK_TA_FRONTMERGE
);
2947 bio
->bi_next
= req
->bio
;
2951 * may not be valid. if the low level driver said
2952 * it didn't need a bounce buffer then it better
2953 * not touch req->buffer either...
2955 req
->buffer
= bio_data(bio
);
2956 req
->current_nr_sectors
= cur_nr_sectors
;
2957 req
->hard_cur_sectors
= cur_nr_sectors
;
2958 req
->sector
= req
->hard_sector
= sector
;
2959 req
->nr_sectors
= req
->hard_nr_sectors
+= nr_sectors
;
2960 req
->ioprio
= ioprio_best(req
->ioprio
, prio
);
2961 drive_stat_acct(req
, nr_sectors
, 0);
2962 if (!attempt_front_merge(q
, req
))
2963 elv_merged_request(q
, req
, el_ret
);
2966 /* ELV_NO_MERGE: elevator says don't/can't merge. */
2973 * Grab a free request. This is might sleep but can not fail.
2974 * Returns with the queue unlocked.
2976 req
= get_request_wait(q
, rw
, bio
);
2979 * After dropping the lock and possibly sleeping here, our request
2980 * may now be mergeable after it had proven unmergeable (above).
2981 * We don't worry about that case for efficiency. It won't happen
2982 * often, and the elevators are able to handle it.
2984 init_request_from_bio(req
, bio
);
2986 spin_lock_irq(q
->queue_lock
);
2987 if (elv_queue_empty(q
))
2989 add_request(q
, req
);
2992 __generic_unplug_device(q
);
2994 spin_unlock_irq(q
->queue_lock
);
2998 bio_endio(bio
, nr_sectors
<< 9, err
);
3003 * If bio->bi_dev is a partition, remap the location
3005 static inline void blk_partition_remap(struct bio
*bio
)
3007 struct block_device
*bdev
= bio
->bi_bdev
;
3009 if (bdev
!= bdev
->bd_contains
) {
3010 struct hd_struct
*p
= bdev
->bd_part
;
3011 const int rw
= bio_data_dir(bio
);
3013 p
->sectors
[rw
] += bio_sectors(bio
);
3016 bio
->bi_sector
+= p
->start_sect
;
3017 bio
->bi_bdev
= bdev
->bd_contains
;
3021 static void handle_bad_sector(struct bio
*bio
)
3023 char b
[BDEVNAME_SIZE
];
3025 printk(KERN_INFO
"attempt to access beyond end of device\n");
3026 printk(KERN_INFO
"%s: rw=%ld, want=%Lu, limit=%Lu\n",
3027 bdevname(bio
->bi_bdev
, b
),
3029 (unsigned long long)bio
->bi_sector
+ bio_sectors(bio
),
3030 (long long)(bio
->bi_bdev
->bd_inode
->i_size
>> 9));
3032 set_bit(BIO_EOF
, &bio
->bi_flags
);
3036 * generic_make_request: hand a buffer to its device driver for I/O
3037 * @bio: The bio describing the location in memory and on the device.
3039 * generic_make_request() is used to make I/O requests of block
3040 * devices. It is passed a &struct bio, which describes the I/O that needs
3043 * generic_make_request() does not return any status. The
3044 * success/failure status of the request, along with notification of
3045 * completion, is delivered asynchronously through the bio->bi_end_io
3046 * function described (one day) else where.
3048 * The caller of generic_make_request must make sure that bi_io_vec
3049 * are set to describe the memory buffer, and that bi_dev and bi_sector are
3050 * set to describe the device address, and the
3051 * bi_end_io and optionally bi_private are set to describe how
3052 * completion notification should be signaled.
3054 * generic_make_request and the drivers it calls may use bi_next if this
3055 * bio happens to be merged with someone else, and may change bi_dev and
3056 * bi_sector for remaps as it sees fit. So the values of these fields
3057 * should NOT be depended on after the call to generic_make_request.
3059 void generic_make_request(struct bio
*bio
)
3063 int ret
, nr_sectors
= bio_sectors(bio
);
3067 /* Test device or partition size, when known. */
3068 maxsector
= bio
->bi_bdev
->bd_inode
->i_size
>> 9;
3070 sector_t sector
= bio
->bi_sector
;
3072 if (maxsector
< nr_sectors
|| maxsector
- nr_sectors
< sector
) {
3074 * This may well happen - the kernel calls bread()
3075 * without checking the size of the device, e.g., when
3076 * mounting a device.
3078 handle_bad_sector(bio
);
3084 * Resolve the mapping until finished. (drivers are
3085 * still free to implement/resolve their own stacking
3086 * by explicitly returning 0)
3088 * NOTE: we don't repeat the blk_size check for each new device.
3089 * Stacking drivers are expected to know what they are doing.
3094 char b
[BDEVNAME_SIZE
];
3096 q
= bdev_get_queue(bio
->bi_bdev
);
3099 "generic_make_request: Trying to access "
3100 "nonexistent block-device %s (%Lu)\n",
3101 bdevname(bio
->bi_bdev
, b
),
3102 (long long) bio
->bi_sector
);
3104 bio_endio(bio
, bio
->bi_size
, -EIO
);
3108 if (unlikely(bio_sectors(bio
) > q
->max_hw_sectors
)) {
3109 printk("bio too big device %s (%u > %u)\n",
3110 bdevname(bio
->bi_bdev
, b
),
3116 if (unlikely(test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
)))
3120 * If this device has partitions, remap block n
3121 * of partition p to block n+start(p) of the disk.
3123 blk_partition_remap(bio
);
3125 if (maxsector
!= -1)
3126 blk_add_trace_remap(q
, bio
, old_dev
, bio
->bi_sector
,
3129 blk_add_trace_bio(q
, bio
, BLK_TA_QUEUE
);
3131 maxsector
= bio
->bi_sector
;
3132 old_dev
= bio
->bi_bdev
->bd_dev
;
3134 ret
= q
->make_request_fn(q
, bio
);
3138 EXPORT_SYMBOL(generic_make_request
);
3141 * submit_bio: submit a bio to the block device layer for I/O
3142 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
3143 * @bio: The &struct bio which describes the I/O
3145 * submit_bio() is very similar in purpose to generic_make_request(), and
3146 * uses that function to do most of the work. Both are fairly rough
3147 * interfaces, @bio must be presetup and ready for I/O.
3150 void submit_bio(int rw
, struct bio
*bio
)
3152 int count
= bio_sectors(bio
);
3154 BIO_BUG_ON(!bio
->bi_size
);
3155 BIO_BUG_ON(!bio
->bi_io_vec
);
3158 count_vm_events(PGPGOUT
, count
);
3160 count_vm_events(PGPGIN
, count
);
3162 if (unlikely(block_dump
)) {
3163 char b
[BDEVNAME_SIZE
];
3164 printk(KERN_DEBUG
"%s(%d): %s block %Lu on %s\n",
3165 current
->comm
, current
->pid
,
3166 (rw
& WRITE
) ? "WRITE" : "READ",
3167 (unsigned long long)bio
->bi_sector
,
3168 bdevname(bio
->bi_bdev
,b
));
3171 generic_make_request(bio
);
3174 EXPORT_SYMBOL(submit_bio
);
3176 static void blk_recalc_rq_segments(struct request
*rq
)
3178 struct bio
*bio
, *prevbio
= NULL
;
3179 int nr_phys_segs
, nr_hw_segs
;
3180 unsigned int phys_size
, hw_size
;
3181 request_queue_t
*q
= rq
->q
;
3186 phys_size
= hw_size
= nr_phys_segs
= nr_hw_segs
= 0;
3187 rq_for_each_bio(bio
, rq
) {
3188 /* Force bio hw/phys segs to be recalculated. */
3189 bio
->bi_flags
&= ~(1 << BIO_SEG_VALID
);
3191 nr_phys_segs
+= bio_phys_segments(q
, bio
);
3192 nr_hw_segs
+= bio_hw_segments(q
, bio
);
3194 int pseg
= phys_size
+ prevbio
->bi_size
+ bio
->bi_size
;
3195 int hseg
= hw_size
+ prevbio
->bi_size
+ bio
->bi_size
;
3197 if (blk_phys_contig_segment(q
, prevbio
, bio
) &&
3198 pseg
<= q
->max_segment_size
) {
3200 phys_size
+= prevbio
->bi_size
+ bio
->bi_size
;
3204 if (blk_hw_contig_segment(q
, prevbio
, bio
) &&
3205 hseg
<= q
->max_segment_size
) {
3207 hw_size
+= prevbio
->bi_size
+ bio
->bi_size
;
3214 rq
->nr_phys_segments
= nr_phys_segs
;
3215 rq
->nr_hw_segments
= nr_hw_segs
;
3218 static void blk_recalc_rq_sectors(struct request
*rq
, int nsect
)
3220 if (blk_fs_request(rq
)) {
3221 rq
->hard_sector
+= nsect
;
3222 rq
->hard_nr_sectors
-= nsect
;
3225 * Move the I/O submission pointers ahead if required.
3227 if ((rq
->nr_sectors
>= rq
->hard_nr_sectors
) &&
3228 (rq
->sector
<= rq
->hard_sector
)) {
3229 rq
->sector
= rq
->hard_sector
;
3230 rq
->nr_sectors
= rq
->hard_nr_sectors
;
3231 rq
->hard_cur_sectors
= bio_cur_sectors(rq
->bio
);
3232 rq
->current_nr_sectors
= rq
->hard_cur_sectors
;
3233 rq
->buffer
= bio_data(rq
->bio
);
3237 * if total number of sectors is less than the first segment
3238 * size, something has gone terribly wrong
3240 if (rq
->nr_sectors
< rq
->current_nr_sectors
) {
3241 printk("blk: request botched\n");
3242 rq
->nr_sectors
= rq
->current_nr_sectors
;
3247 static int __end_that_request_first(struct request
*req
, int uptodate
,
3250 int total_bytes
, bio_nbytes
, error
, next_idx
= 0;
3253 blk_add_trace_rq(req
->q
, req
, BLK_TA_COMPLETE
);
3256 * extend uptodate bool to allow < 0 value to be direct io error
3259 if (end_io_error(uptodate
))
3260 error
= !uptodate
? -EIO
: uptodate
;
3263 * for a REQ_BLOCK_PC request, we want to carry any eventual
3264 * sense key with us all the way through
3266 if (!blk_pc_request(req
))
3270 if (blk_fs_request(req
) && !(req
->cmd_flags
& REQ_QUIET
))
3271 printk("end_request: I/O error, dev %s, sector %llu\n",
3272 req
->rq_disk
? req
->rq_disk
->disk_name
: "?",
3273 (unsigned long long)req
->sector
);
3276 if (blk_fs_request(req
) && req
->rq_disk
) {
3277 const int rw
= rq_data_dir(req
);
3279 disk_stat_add(req
->rq_disk
, sectors
[rw
], nr_bytes
>> 9);
3282 total_bytes
= bio_nbytes
= 0;
3283 while ((bio
= req
->bio
) != NULL
) {
3286 if (nr_bytes
>= bio
->bi_size
) {
3287 req
->bio
= bio
->bi_next
;
3288 nbytes
= bio
->bi_size
;
3289 if (!ordered_bio_endio(req
, bio
, nbytes
, error
))
3290 bio_endio(bio
, nbytes
, error
);
3294 int idx
= bio
->bi_idx
+ next_idx
;
3296 if (unlikely(bio
->bi_idx
>= bio
->bi_vcnt
)) {
3297 blk_dump_rq_flags(req
, "__end_that");
3298 printk("%s: bio idx %d >= vcnt %d\n",
3300 bio
->bi_idx
, bio
->bi_vcnt
);
3304 nbytes
= bio_iovec_idx(bio
, idx
)->bv_len
;
3305 BIO_BUG_ON(nbytes
> bio
->bi_size
);
3308 * not a complete bvec done
3310 if (unlikely(nbytes
> nr_bytes
)) {
3311 bio_nbytes
+= nr_bytes
;
3312 total_bytes
+= nr_bytes
;
3317 * advance to the next vector
3320 bio_nbytes
+= nbytes
;
3323 total_bytes
+= nbytes
;
3326 if ((bio
= req
->bio
)) {
3328 * end more in this run, or just return 'not-done'
3330 if (unlikely(nr_bytes
<= 0))
3342 * if the request wasn't completed, update state
3345 if (!ordered_bio_endio(req
, bio
, bio_nbytes
, error
))
3346 bio_endio(bio
, bio_nbytes
, error
);
3347 bio
->bi_idx
+= next_idx
;
3348 bio_iovec(bio
)->bv_offset
+= nr_bytes
;
3349 bio_iovec(bio
)->bv_len
-= nr_bytes
;
3352 blk_recalc_rq_sectors(req
, total_bytes
>> 9);
3353 blk_recalc_rq_segments(req
);
3358 * end_that_request_first - end I/O on a request
3359 * @req: the request being processed
3360 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3361 * @nr_sectors: number of sectors to end I/O on
3364 * Ends I/O on a number of sectors attached to @req, and sets it up
3365 * for the next range of segments (if any) in the cluster.
3368 * 0 - we are done with this request, call end_that_request_last()
3369 * 1 - still buffers pending for this request
3371 int end_that_request_first(struct request
*req
, int uptodate
, int nr_sectors
)
3373 return __end_that_request_first(req
, uptodate
, nr_sectors
<< 9);
3376 EXPORT_SYMBOL(end_that_request_first
);
3379 * end_that_request_chunk - end I/O on a request
3380 * @req: the request being processed
3381 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3382 * @nr_bytes: number of bytes to complete
3385 * Ends I/O on a number of bytes attached to @req, and sets it up
3386 * for the next range of segments (if any). Like end_that_request_first(),
3387 * but deals with bytes instead of sectors.
3390 * 0 - we are done with this request, call end_that_request_last()
3391 * 1 - still buffers pending for this request
3393 int end_that_request_chunk(struct request
*req
, int uptodate
, int nr_bytes
)
3395 return __end_that_request_first(req
, uptodate
, nr_bytes
);
3398 EXPORT_SYMBOL(end_that_request_chunk
);
3401 * splice the completion data to a local structure and hand off to
3402 * process_completion_queue() to complete the requests
3404 static void blk_done_softirq(struct softirq_action
*h
)
3406 struct list_head
*cpu_list
, local_list
;
3408 local_irq_disable();
3409 cpu_list
= &__get_cpu_var(blk_cpu_done
);
3410 list_replace_init(cpu_list
, &local_list
);
3413 while (!list_empty(&local_list
)) {
3414 struct request
*rq
= list_entry(local_list
.next
, struct request
, donelist
);
3416 list_del_init(&rq
->donelist
);
3417 rq
->q
->softirq_done_fn(rq
);
3421 #ifdef CONFIG_HOTPLUG_CPU
3423 static int blk_cpu_notify(struct notifier_block
*self
, unsigned long action
,
3427 * If a CPU goes away, splice its entries to the current CPU
3428 * and trigger a run of the softirq
3430 if (action
== CPU_DEAD
) {
3431 int cpu
= (unsigned long) hcpu
;
3433 local_irq_disable();
3434 list_splice_init(&per_cpu(blk_cpu_done
, cpu
),
3435 &__get_cpu_var(blk_cpu_done
));
3436 raise_softirq_irqoff(BLOCK_SOFTIRQ
);
3444 static struct notifier_block __devinitdata blk_cpu_notifier
= {
3445 .notifier_call
= blk_cpu_notify
,
3448 #endif /* CONFIG_HOTPLUG_CPU */
3451 * blk_complete_request - end I/O on a request
3452 * @req: the request being processed
3455 * Ends all I/O on a request. It does not handle partial completions,
3456 * unless the driver actually implements this in its completion callback
3457 * through requeueing. Theh actual completion happens out-of-order,
3458 * through a softirq handler. The user must have registered a completion
3459 * callback through blk_queue_softirq_done().
3462 void blk_complete_request(struct request
*req
)
3464 struct list_head
*cpu_list
;
3465 unsigned long flags
;
3467 BUG_ON(!req
->q
->softirq_done_fn
);
3469 local_irq_save(flags
);
3471 cpu_list
= &__get_cpu_var(blk_cpu_done
);
3472 list_add_tail(&req
->donelist
, cpu_list
);
3473 raise_softirq_irqoff(BLOCK_SOFTIRQ
);
3475 local_irq_restore(flags
);
3478 EXPORT_SYMBOL(blk_complete_request
);
3481 * queue lock must be held
3483 void end_that_request_last(struct request
*req
, int uptodate
)
3485 struct gendisk
*disk
= req
->rq_disk
;
3489 * extend uptodate bool to allow < 0 value to be direct io error
3492 if (end_io_error(uptodate
))
3493 error
= !uptodate
? -EIO
: uptodate
;
3495 if (unlikely(laptop_mode
) && blk_fs_request(req
))
3496 laptop_io_completion();
3499 * Account IO completion. bar_rq isn't accounted as a normal
3500 * IO on queueing nor completion. Accounting the containing
3501 * request is enough.
3503 if (disk
&& blk_fs_request(req
) && req
!= &req
->q
->bar_rq
) {
3504 unsigned long duration
= jiffies
- req
->start_time
;
3505 const int rw
= rq_data_dir(req
);
3507 __disk_stat_inc(disk
, ios
[rw
]);
3508 __disk_stat_add(disk
, ticks
[rw
], duration
);
3509 disk_round_stats(disk
);
3513 req
->end_io(req
, error
);
3515 __blk_put_request(req
->q
, req
);
3518 EXPORT_SYMBOL(end_that_request_last
);
3520 void end_request(struct request
*req
, int uptodate
)
3522 if (!end_that_request_first(req
, uptodate
, req
->hard_cur_sectors
)) {
3523 add_disk_randomness(req
->rq_disk
);
3524 blkdev_dequeue_request(req
);
3525 end_that_request_last(req
, uptodate
);
3529 EXPORT_SYMBOL(end_request
);
3531 void blk_rq_bio_prep(request_queue_t
*q
, struct request
*rq
, struct bio
*bio
)
3533 /* first two bits are identical in rq->cmd_flags and bio->bi_rw */
3534 rq
->cmd_flags
|= (bio
->bi_rw
& 3);
3536 rq
->nr_phys_segments
= bio_phys_segments(q
, bio
);
3537 rq
->nr_hw_segments
= bio_hw_segments(q
, bio
);
3538 rq
->current_nr_sectors
= bio_cur_sectors(bio
);
3539 rq
->hard_cur_sectors
= rq
->current_nr_sectors
;
3540 rq
->hard_nr_sectors
= rq
->nr_sectors
= bio_sectors(bio
);
3541 rq
->buffer
= bio_data(bio
);
3543 rq
->bio
= rq
->biotail
= bio
;
3546 EXPORT_SYMBOL(blk_rq_bio_prep
);
3548 int kblockd_schedule_work(struct work_struct
*work
)
3550 return queue_work(kblockd_workqueue
, work
);
3553 EXPORT_SYMBOL(kblockd_schedule_work
);
3555 void kblockd_flush(void)
3557 flush_workqueue(kblockd_workqueue
);
3559 EXPORT_SYMBOL(kblockd_flush
);
3561 int __init
blk_dev_init(void)
3565 kblockd_workqueue
= create_workqueue("kblockd");
3566 if (!kblockd_workqueue
)
3567 panic("Failed to create kblockd\n");
3569 request_cachep
= kmem_cache_create("blkdev_requests",
3570 sizeof(struct request
), 0, SLAB_PANIC
, NULL
, NULL
);
3572 requestq_cachep
= kmem_cache_create("blkdev_queue",
3573 sizeof(request_queue_t
), 0, SLAB_PANIC
, NULL
, NULL
);
3575 iocontext_cachep
= kmem_cache_create("blkdev_ioc",
3576 sizeof(struct io_context
), 0, SLAB_PANIC
, NULL
, NULL
);
3578 for_each_possible_cpu(i
)
3579 INIT_LIST_HEAD(&per_cpu(blk_cpu_done
, i
));
3581 open_softirq(BLOCK_SOFTIRQ
, blk_done_softirq
, NULL
);
3582 register_hotcpu_notifier(&blk_cpu_notifier
);
3584 blk_max_low_pfn
= max_low_pfn
;
3585 blk_max_pfn
= max_pfn
;
3591 * IO Context helper functions
3593 void put_io_context(struct io_context
*ioc
)
3598 BUG_ON(atomic_read(&ioc
->refcount
) == 0);
3600 if (atomic_dec_and_test(&ioc
->refcount
)) {
3601 struct cfq_io_context
*cic
;
3604 if (ioc
->aic
&& ioc
->aic
->dtor
)
3605 ioc
->aic
->dtor(ioc
->aic
);
3606 if (ioc
->cic_root
.rb_node
!= NULL
) {
3607 struct rb_node
*n
= rb_first(&ioc
->cic_root
);
3609 cic
= rb_entry(n
, struct cfq_io_context
, rb_node
);
3614 kmem_cache_free(iocontext_cachep
, ioc
);
3617 EXPORT_SYMBOL(put_io_context
);
3619 /* Called by the exitting task */
3620 void exit_io_context(void)
3622 unsigned long flags
;
3623 struct io_context
*ioc
;
3624 struct cfq_io_context
*cic
;
3626 local_irq_save(flags
);
3628 ioc
= current
->io_context
;
3629 current
->io_context
= NULL
;
3631 task_unlock(current
);
3632 local_irq_restore(flags
);
3634 if (ioc
->aic
&& ioc
->aic
->exit
)
3635 ioc
->aic
->exit(ioc
->aic
);
3636 if (ioc
->cic_root
.rb_node
!= NULL
) {
3637 cic
= rb_entry(rb_first(&ioc
->cic_root
), struct cfq_io_context
, rb_node
);
3641 put_io_context(ioc
);
3645 * If the current task has no IO context then create one and initialise it.
3646 * Otherwise, return its existing IO context.
3648 * This returned IO context doesn't have a specifically elevated refcount,
3649 * but since the current task itself holds a reference, the context can be
3650 * used in general code, so long as it stays within `current` context.
3652 struct io_context
*current_io_context(gfp_t gfp_flags
)
3654 struct task_struct
*tsk
= current
;
3655 struct io_context
*ret
;
3657 ret
= tsk
->io_context
;
3661 ret
= kmem_cache_alloc(iocontext_cachep
, gfp_flags
);
3663 atomic_set(&ret
->refcount
, 1);
3664 ret
->task
= current
;
3665 ret
->set_ioprio
= NULL
;
3666 ret
->last_waited
= jiffies
; /* doesn't matter... */
3667 ret
->nr_batch_requests
= 0; /* because this is 0 */
3669 ret
->cic_root
.rb_node
= NULL
;
3670 /* make sure set_task_ioprio() sees the settings above */
3672 tsk
->io_context
= ret
;
3677 EXPORT_SYMBOL(current_io_context
);
3680 * If the current task has no IO context then create one and initialise it.
3681 * If it does have a context, take a ref on it.
3683 * This is always called in the context of the task which submitted the I/O.
3685 struct io_context
*get_io_context(gfp_t gfp_flags
)
3687 struct io_context
*ret
;
3688 ret
= current_io_context(gfp_flags
);
3690 atomic_inc(&ret
->refcount
);
3693 EXPORT_SYMBOL(get_io_context
);
3695 void copy_io_context(struct io_context
**pdst
, struct io_context
**psrc
)
3697 struct io_context
*src
= *psrc
;
3698 struct io_context
*dst
= *pdst
;
3701 BUG_ON(atomic_read(&src
->refcount
) == 0);
3702 atomic_inc(&src
->refcount
);
3703 put_io_context(dst
);
3707 EXPORT_SYMBOL(copy_io_context
);
3709 void swap_io_context(struct io_context
**ioc1
, struct io_context
**ioc2
)
3711 struct io_context
*temp
;
3716 EXPORT_SYMBOL(swap_io_context
);
3721 struct queue_sysfs_entry
{
3722 struct attribute attr
;
3723 ssize_t (*show
)(struct request_queue
*, char *);
3724 ssize_t (*store
)(struct request_queue
*, const char *, size_t);
3728 queue_var_show(unsigned int var
, char *page
)
3730 return sprintf(page
, "%d\n", var
);
3734 queue_var_store(unsigned long *var
, const char *page
, size_t count
)
3736 char *p
= (char *) page
;
3738 *var
= simple_strtoul(p
, &p
, 10);
3742 static ssize_t
queue_requests_show(struct request_queue
*q
, char *page
)
3744 return queue_var_show(q
->nr_requests
, (page
));
3748 queue_requests_store(struct request_queue
*q
, const char *page
, size_t count
)
3750 struct request_list
*rl
= &q
->rq
;
3752 int ret
= queue_var_store(&nr
, page
, count
);
3753 if (nr
< BLKDEV_MIN_RQ
)
3756 spin_lock_irq(q
->queue_lock
);
3757 q
->nr_requests
= nr
;
3758 blk_queue_congestion_threshold(q
);
3760 if (rl
->count
[READ
] >= queue_congestion_on_threshold(q
))
3761 set_queue_congested(q
, READ
);
3762 else if (rl
->count
[READ
] < queue_congestion_off_threshold(q
))
3763 clear_queue_congested(q
, READ
);
3765 if (rl
->count
[WRITE
] >= queue_congestion_on_threshold(q
))
3766 set_queue_congested(q
, WRITE
);
3767 else if (rl
->count
[WRITE
] < queue_congestion_off_threshold(q
))
3768 clear_queue_congested(q
, WRITE
);
3770 if (rl
->count
[READ
] >= q
->nr_requests
) {
3771 blk_set_queue_full(q
, READ
);
3772 } else if (rl
->count
[READ
]+1 <= q
->nr_requests
) {
3773 blk_clear_queue_full(q
, READ
);
3774 wake_up(&rl
->wait
[READ
]);
3777 if (rl
->count
[WRITE
] >= q
->nr_requests
) {
3778 blk_set_queue_full(q
, WRITE
);
3779 } else if (rl
->count
[WRITE
]+1 <= q
->nr_requests
) {
3780 blk_clear_queue_full(q
, WRITE
);
3781 wake_up(&rl
->wait
[WRITE
]);
3783 spin_unlock_irq(q
->queue_lock
);
3787 static ssize_t
queue_ra_show(struct request_queue
*q
, char *page
)
3789 int ra_kb
= q
->backing_dev_info
.ra_pages
<< (PAGE_CACHE_SHIFT
- 10);
3791 return queue_var_show(ra_kb
, (page
));
3795 queue_ra_store(struct request_queue
*q
, const char *page
, size_t count
)
3797 unsigned long ra_kb
;
3798 ssize_t ret
= queue_var_store(&ra_kb
, page
, count
);
3800 spin_lock_irq(q
->queue_lock
);
3801 if (ra_kb
> (q
->max_sectors
>> 1))
3802 ra_kb
= (q
->max_sectors
>> 1);
3804 q
->backing_dev_info
.ra_pages
= ra_kb
>> (PAGE_CACHE_SHIFT
- 10);
3805 spin_unlock_irq(q
->queue_lock
);
3810 static ssize_t
queue_max_sectors_show(struct request_queue
*q
, char *page
)
3812 int max_sectors_kb
= q
->max_sectors
>> 1;
3814 return queue_var_show(max_sectors_kb
, (page
));
3818 queue_max_sectors_store(struct request_queue
*q
, const char *page
, size_t count
)
3820 unsigned long max_sectors_kb
,
3821 max_hw_sectors_kb
= q
->max_hw_sectors
>> 1,
3822 page_kb
= 1 << (PAGE_CACHE_SHIFT
- 10);
3823 ssize_t ret
= queue_var_store(&max_sectors_kb
, page
, count
);
3826 if (max_sectors_kb
> max_hw_sectors_kb
|| max_sectors_kb
< page_kb
)
3829 * Take the queue lock to update the readahead and max_sectors
3830 * values synchronously:
3832 spin_lock_irq(q
->queue_lock
);
3834 * Trim readahead window as well, if necessary:
3836 ra_kb
= q
->backing_dev_info
.ra_pages
<< (PAGE_CACHE_SHIFT
- 10);
3837 if (ra_kb
> max_sectors_kb
)
3838 q
->backing_dev_info
.ra_pages
=
3839 max_sectors_kb
>> (PAGE_CACHE_SHIFT
- 10);
3841 q
->max_sectors
= max_sectors_kb
<< 1;
3842 spin_unlock_irq(q
->queue_lock
);
3847 static ssize_t
queue_max_hw_sectors_show(struct request_queue
*q
, char *page
)
3849 int max_hw_sectors_kb
= q
->max_hw_sectors
>> 1;
3851 return queue_var_show(max_hw_sectors_kb
, (page
));
3855 static struct queue_sysfs_entry queue_requests_entry
= {
3856 .attr
= {.name
= "nr_requests", .mode
= S_IRUGO
| S_IWUSR
},
3857 .show
= queue_requests_show
,
3858 .store
= queue_requests_store
,
3861 static struct queue_sysfs_entry queue_ra_entry
= {
3862 .attr
= {.name
= "read_ahead_kb", .mode
= S_IRUGO
| S_IWUSR
},
3863 .show
= queue_ra_show
,
3864 .store
= queue_ra_store
,
3867 static struct queue_sysfs_entry queue_max_sectors_entry
= {
3868 .attr
= {.name
= "max_sectors_kb", .mode
= S_IRUGO
| S_IWUSR
},
3869 .show
= queue_max_sectors_show
,
3870 .store
= queue_max_sectors_store
,
3873 static struct queue_sysfs_entry queue_max_hw_sectors_entry
= {
3874 .attr
= {.name
= "max_hw_sectors_kb", .mode
= S_IRUGO
},
3875 .show
= queue_max_hw_sectors_show
,
3878 static struct queue_sysfs_entry queue_iosched_entry
= {
3879 .attr
= {.name
= "scheduler", .mode
= S_IRUGO
| S_IWUSR
},
3880 .show
= elv_iosched_show
,
3881 .store
= elv_iosched_store
,
3884 static struct attribute
*default_attrs
[] = {
3885 &queue_requests_entry
.attr
,
3886 &queue_ra_entry
.attr
,
3887 &queue_max_hw_sectors_entry
.attr
,
3888 &queue_max_sectors_entry
.attr
,
3889 &queue_iosched_entry
.attr
,
3893 #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
3896 queue_attr_show(struct kobject
*kobj
, struct attribute
*attr
, char *page
)
3898 struct queue_sysfs_entry
*entry
= to_queue(attr
);
3899 request_queue_t
*q
= container_of(kobj
, struct request_queue
, kobj
);
3904 mutex_lock(&q
->sysfs_lock
);
3905 if (test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
)) {
3906 mutex_unlock(&q
->sysfs_lock
);
3909 res
= entry
->show(q
, page
);
3910 mutex_unlock(&q
->sysfs_lock
);
3915 queue_attr_store(struct kobject
*kobj
, struct attribute
*attr
,
3916 const char *page
, size_t length
)
3918 struct queue_sysfs_entry
*entry
= to_queue(attr
);
3919 request_queue_t
*q
= container_of(kobj
, struct request_queue
, kobj
);
3925 mutex_lock(&q
->sysfs_lock
);
3926 if (test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
)) {
3927 mutex_unlock(&q
->sysfs_lock
);
3930 res
= entry
->store(q
, page
, length
);
3931 mutex_unlock(&q
->sysfs_lock
);
3935 static struct sysfs_ops queue_sysfs_ops
= {
3936 .show
= queue_attr_show
,
3937 .store
= queue_attr_store
,
3940 static struct kobj_type queue_ktype
= {
3941 .sysfs_ops
= &queue_sysfs_ops
,
3942 .default_attrs
= default_attrs
,
3943 .release
= blk_release_queue
,
3946 int blk_register_queue(struct gendisk
*disk
)
3950 request_queue_t
*q
= disk
->queue
;
3952 if (!q
|| !q
->request_fn
)
3955 q
->kobj
.parent
= kobject_get(&disk
->kobj
);
3957 ret
= kobject_add(&q
->kobj
);
3961 kobject_uevent(&q
->kobj
, KOBJ_ADD
);
3963 ret
= elv_register_queue(q
);
3965 kobject_uevent(&q
->kobj
, KOBJ_REMOVE
);
3966 kobject_del(&q
->kobj
);
3973 void blk_unregister_queue(struct gendisk
*disk
)
3975 request_queue_t
*q
= disk
->queue
;
3977 if (q
&& q
->request_fn
) {
3978 elv_unregister_queue(q
);
3980 kobject_uevent(&q
->kobj
, KOBJ_REMOVE
);
3981 kobject_del(&q
->kobj
);
3982 kobject_put(&disk
->kobj
);