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/task_io_accounting_ops.h>
29 #include <linux/interrupt.h>
30 #include <linux/cpu.h>
31 #include <linux/blktrace_api.h>
32 #include <linux/fault-inject.h>
37 #include <scsi/scsi_cmnd.h>
39 static void blk_unplug_work(struct work_struct
*work
);
40 static void blk_unplug_timeout(unsigned long data
);
41 static void drive_stat_acct(struct request
*rq
, int nr_sectors
, int new_io
);
42 static void init_request_from_bio(struct request
*req
, struct bio
*bio
);
43 static int __make_request(struct request_queue
*q
, struct bio
*bio
);
44 static struct io_context
*current_io_context(gfp_t gfp_flags
, int node
);
45 static void blk_recalc_rq_segments(struct request
*rq
);
48 * For the allocated request tables
50 static struct kmem_cache
*request_cachep
;
53 * For queue allocation
55 static struct kmem_cache
*requestq_cachep
;
58 * For io context allocations
60 static struct kmem_cache
*iocontext_cachep
;
63 * Controlling structure to kblockd
65 static struct workqueue_struct
*kblockd_workqueue
;
67 unsigned long blk_max_low_pfn
, blk_max_pfn
;
69 EXPORT_SYMBOL(blk_max_low_pfn
);
70 EXPORT_SYMBOL(blk_max_pfn
);
72 static DEFINE_PER_CPU(struct list_head
, blk_cpu_done
);
74 /* Amount of time in which a process may batch requests */
75 #define BLK_BATCH_TIME (HZ/50UL)
77 /* Number of requests a "batching" process may submit */
78 #define BLK_BATCH_REQ 32
81 * Return the threshold (number of used requests) at which the queue is
82 * considered to be congested. It include a little hysteresis to keep the
83 * context switch rate down.
85 static inline int queue_congestion_on_threshold(struct request_queue
*q
)
87 return q
->nr_congestion_on
;
91 * The threshold at which a queue is considered to be uncongested
93 static inline int queue_congestion_off_threshold(struct request_queue
*q
)
95 return q
->nr_congestion_off
;
98 static void blk_queue_congestion_threshold(struct request_queue
*q
)
102 nr
= q
->nr_requests
- (q
->nr_requests
/ 8) + 1;
103 if (nr
> q
->nr_requests
)
105 q
->nr_congestion_on
= nr
;
107 nr
= q
->nr_requests
- (q
->nr_requests
/ 8) - (q
->nr_requests
/ 16) - 1;
110 q
->nr_congestion_off
= nr
;
114 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
117 * Locates the passed device's request queue and returns the address of its
120 * Will return NULL if the request queue cannot be located.
122 struct backing_dev_info
*blk_get_backing_dev_info(struct block_device
*bdev
)
124 struct backing_dev_info
*ret
= NULL
;
125 struct request_queue
*q
= bdev_get_queue(bdev
);
128 ret
= &q
->backing_dev_info
;
131 EXPORT_SYMBOL(blk_get_backing_dev_info
);
134 * blk_queue_prep_rq - set a prepare_request function for queue
136 * @pfn: prepare_request function
138 * It's possible for a queue to register a prepare_request callback which
139 * is invoked before the request is handed to the request_fn. The goal of
140 * the function is to prepare a request for I/O, it can be used to build a
141 * cdb from the request data for instance.
144 void blk_queue_prep_rq(struct request_queue
*q
, prep_rq_fn
*pfn
)
149 EXPORT_SYMBOL(blk_queue_prep_rq
);
152 * blk_queue_merge_bvec - set a merge_bvec function for queue
154 * @mbfn: merge_bvec_fn
156 * Usually queues have static limitations on the max sectors or segments that
157 * we can put in a request. Stacking drivers may have some settings that
158 * are dynamic, and thus we have to query the queue whether it is ok to
159 * add a new bio_vec to a bio at a given offset or not. If the block device
160 * has such limitations, it needs to register a merge_bvec_fn to control
161 * the size of bio's sent to it. Note that a block device *must* allow a
162 * single page to be added to an empty bio. The block device driver may want
163 * to use the bio_split() function to deal with these bio's. By default
164 * no merge_bvec_fn is defined for a queue, and only the fixed limits are
167 void blk_queue_merge_bvec(struct request_queue
*q
, merge_bvec_fn
*mbfn
)
169 q
->merge_bvec_fn
= mbfn
;
172 EXPORT_SYMBOL(blk_queue_merge_bvec
);
174 void blk_queue_softirq_done(struct request_queue
*q
, softirq_done_fn
*fn
)
176 q
->softirq_done_fn
= fn
;
179 EXPORT_SYMBOL(blk_queue_softirq_done
);
182 * blk_queue_make_request - define an alternate make_request function for a device
183 * @q: the request queue for the device to be affected
184 * @mfn: the alternate make_request function
187 * The normal way for &struct bios to be passed to a device
188 * driver is for them to be collected into requests on a request
189 * queue, and then to allow the device driver to select requests
190 * off that queue when it is ready. This works well for many block
191 * devices. However some block devices (typically virtual devices
192 * such as md or lvm) do not benefit from the processing on the
193 * request queue, and are served best by having the requests passed
194 * directly to them. This can be achieved by providing a function
195 * to blk_queue_make_request().
198 * The driver that does this *must* be able to deal appropriately
199 * with buffers in "highmemory". This can be accomplished by either calling
200 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
201 * blk_queue_bounce() to create a buffer in normal memory.
203 void blk_queue_make_request(struct request_queue
* q
, make_request_fn
* mfn
)
208 q
->nr_requests
= BLKDEV_MAX_RQ
;
209 blk_queue_max_phys_segments(q
, MAX_PHYS_SEGMENTS
);
210 blk_queue_max_hw_segments(q
, MAX_HW_SEGMENTS
);
211 q
->make_request_fn
= mfn
;
212 q
->backing_dev_info
.ra_pages
= (VM_MAX_READAHEAD
* 1024) / PAGE_CACHE_SIZE
;
213 q
->backing_dev_info
.state
= 0;
214 q
->backing_dev_info
.capabilities
= BDI_CAP_MAP_COPY
;
215 blk_queue_max_sectors(q
, SAFE_MAX_SECTORS
);
216 blk_queue_hardsect_size(q
, 512);
217 blk_queue_dma_alignment(q
, 511);
218 blk_queue_congestion_threshold(q
);
219 q
->nr_batching
= BLK_BATCH_REQ
;
221 q
->unplug_thresh
= 4; /* hmm */
222 q
->unplug_delay
= (3 * HZ
) / 1000; /* 3 milliseconds */
223 if (q
->unplug_delay
== 0)
226 INIT_WORK(&q
->unplug_work
, blk_unplug_work
);
228 q
->unplug_timer
.function
= blk_unplug_timeout
;
229 q
->unplug_timer
.data
= (unsigned long)q
;
232 * by default assume old behaviour and bounce for any highmem page
234 blk_queue_bounce_limit(q
, BLK_BOUNCE_HIGH
);
237 EXPORT_SYMBOL(blk_queue_make_request
);
239 static void rq_init(struct request_queue
*q
, struct request
*rq
)
241 INIT_LIST_HEAD(&rq
->queuelist
);
242 INIT_LIST_HEAD(&rq
->donelist
);
245 rq
->bio
= rq
->biotail
= NULL
;
246 INIT_HLIST_NODE(&rq
->hash
);
247 RB_CLEAR_NODE(&rq
->rb_node
);
255 rq
->nr_phys_segments
= 0;
258 rq
->end_io_data
= NULL
;
259 rq
->completion_data
= NULL
;
264 * blk_queue_ordered - does this queue support ordered writes
265 * @q: the request queue
266 * @ordered: one of QUEUE_ORDERED_*
267 * @prepare_flush_fn: rq setup helper for cache flush ordered writes
270 * For journalled file systems, doing ordered writes on a commit
271 * block instead of explicitly doing wait_on_buffer (which is bad
272 * for performance) can be a big win. Block drivers supporting this
273 * feature should call this function and indicate so.
276 int blk_queue_ordered(struct request_queue
*q
, unsigned ordered
,
277 prepare_flush_fn
*prepare_flush_fn
)
279 if (ordered
& (QUEUE_ORDERED_PREFLUSH
| QUEUE_ORDERED_POSTFLUSH
) &&
280 prepare_flush_fn
== NULL
) {
281 printk(KERN_ERR
"blk_queue_ordered: prepare_flush_fn required\n");
285 if (ordered
!= QUEUE_ORDERED_NONE
&&
286 ordered
!= QUEUE_ORDERED_DRAIN
&&
287 ordered
!= QUEUE_ORDERED_DRAIN_FLUSH
&&
288 ordered
!= QUEUE_ORDERED_DRAIN_FUA
&&
289 ordered
!= QUEUE_ORDERED_TAG
&&
290 ordered
!= QUEUE_ORDERED_TAG_FLUSH
&&
291 ordered
!= QUEUE_ORDERED_TAG_FUA
) {
292 printk(KERN_ERR
"blk_queue_ordered: bad value %d\n", ordered
);
296 q
->ordered
= ordered
;
297 q
->next_ordered
= ordered
;
298 q
->prepare_flush_fn
= prepare_flush_fn
;
303 EXPORT_SYMBOL(blk_queue_ordered
);
306 * blk_queue_issue_flush_fn - set function for issuing a flush
307 * @q: the request queue
308 * @iff: the function to be called issuing the flush
311 * If a driver supports issuing a flush command, the support is notified
312 * to the block layer by defining it through this call.
315 void blk_queue_issue_flush_fn(struct request_queue
*q
, issue_flush_fn
*iff
)
317 q
->issue_flush_fn
= iff
;
320 EXPORT_SYMBOL(blk_queue_issue_flush_fn
);
323 * Cache flushing for ordered writes handling
325 inline unsigned blk_ordered_cur_seq(struct request_queue
*q
)
329 return 1 << ffz(q
->ordseq
);
332 unsigned blk_ordered_req_seq(struct request
*rq
)
334 struct request_queue
*q
= rq
->q
;
336 BUG_ON(q
->ordseq
== 0);
338 if (rq
== &q
->pre_flush_rq
)
339 return QUEUE_ORDSEQ_PREFLUSH
;
340 if (rq
== &q
->bar_rq
)
341 return QUEUE_ORDSEQ_BAR
;
342 if (rq
== &q
->post_flush_rq
)
343 return QUEUE_ORDSEQ_POSTFLUSH
;
346 * !fs requests don't need to follow barrier ordering. Always
347 * put them at the front. This fixes the following deadlock.
349 * http://thread.gmane.org/gmane.linux.kernel/537473
351 if (!blk_fs_request(rq
))
352 return QUEUE_ORDSEQ_DRAIN
;
354 if ((rq
->cmd_flags
& REQ_ORDERED_COLOR
) ==
355 (q
->orig_bar_rq
->cmd_flags
& REQ_ORDERED_COLOR
))
356 return QUEUE_ORDSEQ_DRAIN
;
358 return QUEUE_ORDSEQ_DONE
;
361 void blk_ordered_complete_seq(struct request_queue
*q
, unsigned seq
, int error
)
366 if (error
&& !q
->orderr
)
369 BUG_ON(q
->ordseq
& seq
);
372 if (blk_ordered_cur_seq(q
) != QUEUE_ORDSEQ_DONE
)
376 * Okay, sequence complete.
379 uptodate
= q
->orderr
? q
->orderr
: 1;
383 end_that_request_first(rq
, uptodate
, rq
->hard_nr_sectors
);
384 end_that_request_last(rq
, uptodate
);
387 static void pre_flush_end_io(struct request
*rq
, int error
)
389 elv_completed_request(rq
->q
, rq
);
390 blk_ordered_complete_seq(rq
->q
, QUEUE_ORDSEQ_PREFLUSH
, error
);
393 static void bar_end_io(struct request
*rq
, int error
)
395 elv_completed_request(rq
->q
, rq
);
396 blk_ordered_complete_seq(rq
->q
, QUEUE_ORDSEQ_BAR
, error
);
399 static void post_flush_end_io(struct request
*rq
, int error
)
401 elv_completed_request(rq
->q
, rq
);
402 blk_ordered_complete_seq(rq
->q
, QUEUE_ORDSEQ_POSTFLUSH
, error
);
405 static void queue_flush(struct request_queue
*q
, unsigned which
)
408 rq_end_io_fn
*end_io
;
410 if (which
== QUEUE_ORDERED_PREFLUSH
) {
411 rq
= &q
->pre_flush_rq
;
412 end_io
= pre_flush_end_io
;
414 rq
= &q
->post_flush_rq
;
415 end_io
= post_flush_end_io
;
418 rq
->cmd_flags
= REQ_HARDBARRIER
;
420 rq
->elevator_private
= NULL
;
421 rq
->elevator_private2
= NULL
;
422 rq
->rq_disk
= q
->bar_rq
.rq_disk
;
424 q
->prepare_flush_fn(q
, rq
);
426 elv_insert(q
, rq
, ELEVATOR_INSERT_FRONT
);
429 static inline struct request
*start_ordered(struct request_queue
*q
,
434 q
->ordered
= q
->next_ordered
;
435 q
->ordseq
|= QUEUE_ORDSEQ_STARTED
;
438 * Prep proxy barrier request.
440 blkdev_dequeue_request(rq
);
445 if (bio_data_dir(q
->orig_bar_rq
->bio
) == WRITE
)
446 rq
->cmd_flags
|= REQ_RW
;
447 rq
->cmd_flags
|= q
->ordered
& QUEUE_ORDERED_FUA
? REQ_FUA
: 0;
448 rq
->elevator_private
= NULL
;
449 rq
->elevator_private2
= NULL
;
450 init_request_from_bio(rq
, q
->orig_bar_rq
->bio
);
451 rq
->end_io
= bar_end_io
;
454 * Queue ordered sequence. As we stack them at the head, we
455 * need to queue in reverse order. Note that we rely on that
456 * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs
457 * request gets inbetween ordered sequence.
459 if (q
->ordered
& QUEUE_ORDERED_POSTFLUSH
)
460 queue_flush(q
, QUEUE_ORDERED_POSTFLUSH
);
462 q
->ordseq
|= QUEUE_ORDSEQ_POSTFLUSH
;
464 elv_insert(q
, rq
, ELEVATOR_INSERT_FRONT
);
466 if (q
->ordered
& QUEUE_ORDERED_PREFLUSH
) {
467 queue_flush(q
, QUEUE_ORDERED_PREFLUSH
);
468 rq
= &q
->pre_flush_rq
;
470 q
->ordseq
|= QUEUE_ORDSEQ_PREFLUSH
;
472 if ((q
->ordered
& QUEUE_ORDERED_TAG
) || q
->in_flight
== 0)
473 q
->ordseq
|= QUEUE_ORDSEQ_DRAIN
;
480 int blk_do_ordered(struct request_queue
*q
, struct request
**rqp
)
482 struct request
*rq
= *rqp
;
483 int is_barrier
= blk_fs_request(rq
) && blk_barrier_rq(rq
);
489 if (q
->next_ordered
!= QUEUE_ORDERED_NONE
) {
490 *rqp
= start_ordered(q
, rq
);
494 * This can happen when the queue switches to
495 * ORDERED_NONE while this request is on it.
497 blkdev_dequeue_request(rq
);
498 end_that_request_first(rq
, -EOPNOTSUPP
,
499 rq
->hard_nr_sectors
);
500 end_that_request_last(rq
, -EOPNOTSUPP
);
507 * Ordered sequence in progress
510 /* Special requests are not subject to ordering rules. */
511 if (!blk_fs_request(rq
) &&
512 rq
!= &q
->pre_flush_rq
&& rq
!= &q
->post_flush_rq
)
515 if (q
->ordered
& QUEUE_ORDERED_TAG
) {
516 /* Ordered by tag. Blocking the next barrier is enough. */
517 if (is_barrier
&& rq
!= &q
->bar_rq
)
520 /* Ordered by draining. Wait for turn. */
521 WARN_ON(blk_ordered_req_seq(rq
) < blk_ordered_cur_seq(q
));
522 if (blk_ordered_req_seq(rq
) > blk_ordered_cur_seq(q
))
529 static int flush_dry_bio_endio(struct bio
*bio
, unsigned int bytes
, int error
)
531 struct request_queue
*q
= bio
->bi_private
;
534 * This is dry run, restore bio_sector and size. We'll finish
535 * this request again with the original bi_end_io after an
536 * error occurs or post flush is complete.
544 set_bit(BIO_UPTODATE
, &bio
->bi_flags
);
545 bio
->bi_size
= q
->bi_size
;
546 bio
->bi_sector
-= (q
->bi_size
>> 9);
552 static int ordered_bio_endio(struct request
*rq
, struct bio
*bio
,
553 unsigned int nbytes
, int error
)
555 struct request_queue
*q
= rq
->q
;
559 if (&q
->bar_rq
!= rq
)
563 * Okay, this is the barrier request in progress, dry finish it.
565 if (error
&& !q
->orderr
)
568 endio
= bio
->bi_end_io
;
569 private = bio
->bi_private
;
570 bio
->bi_end_io
= flush_dry_bio_endio
;
573 bio_endio(bio
, nbytes
, error
);
575 bio
->bi_end_io
= endio
;
576 bio
->bi_private
= private;
582 * blk_queue_bounce_limit - set bounce buffer limit for queue
583 * @q: the request queue for the device
584 * @dma_addr: bus address limit
587 * Different hardware can have different requirements as to what pages
588 * it can do I/O directly to. A low level driver can call
589 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
590 * buffers for doing I/O to pages residing above @page.
592 void blk_queue_bounce_limit(struct request_queue
*q
, u64 dma_addr
)
594 unsigned long bounce_pfn
= dma_addr
>> PAGE_SHIFT
;
597 q
->bounce_gfp
= GFP_NOIO
;
598 #if BITS_PER_LONG == 64
599 /* Assume anything <= 4GB can be handled by IOMMU.
600 Actually some IOMMUs can handle everything, but I don't
601 know of a way to test this here. */
602 if (bounce_pfn
< (min_t(u64
,0xffffffff,BLK_BOUNCE_HIGH
) >> PAGE_SHIFT
))
604 q
->bounce_pfn
= max_low_pfn
;
606 if (bounce_pfn
< blk_max_low_pfn
)
608 q
->bounce_pfn
= bounce_pfn
;
611 init_emergency_isa_pool();
612 q
->bounce_gfp
= GFP_NOIO
| GFP_DMA
;
613 q
->bounce_pfn
= bounce_pfn
;
617 EXPORT_SYMBOL(blk_queue_bounce_limit
);
620 * blk_queue_max_sectors - set max sectors for a request for this queue
621 * @q: the request queue for the device
622 * @max_sectors: max sectors in the usual 512b unit
625 * Enables a low level driver to set an upper limit on the size of
628 void blk_queue_max_sectors(struct request_queue
*q
, unsigned int max_sectors
)
630 if ((max_sectors
<< 9) < PAGE_CACHE_SIZE
) {
631 max_sectors
= 1 << (PAGE_CACHE_SHIFT
- 9);
632 printk("%s: set to minimum %d\n", __FUNCTION__
, max_sectors
);
635 if (BLK_DEF_MAX_SECTORS
> max_sectors
)
636 q
->max_hw_sectors
= q
->max_sectors
= max_sectors
;
638 q
->max_sectors
= BLK_DEF_MAX_SECTORS
;
639 q
->max_hw_sectors
= max_sectors
;
643 EXPORT_SYMBOL(blk_queue_max_sectors
);
646 * blk_queue_max_phys_segments - set max phys segments for a request for this queue
647 * @q: the request queue for the device
648 * @max_segments: max number of segments
651 * Enables a low level driver to set an upper limit on the number of
652 * physical data segments in a request. This would be the largest sized
653 * scatter list the driver could handle.
655 void blk_queue_max_phys_segments(struct request_queue
*q
,
656 unsigned short max_segments
)
660 printk("%s: set to minimum %d\n", __FUNCTION__
, max_segments
);
663 q
->max_phys_segments
= max_segments
;
666 EXPORT_SYMBOL(blk_queue_max_phys_segments
);
669 * blk_queue_max_hw_segments - set max hw segments for a request for this queue
670 * @q: the request queue for the device
671 * @max_segments: max number of segments
674 * Enables a low level driver to set an upper limit on the number of
675 * hw data segments in a request. This would be the largest number of
676 * address/length pairs the host adapter can actually give as once
679 void blk_queue_max_hw_segments(struct request_queue
*q
,
680 unsigned short max_segments
)
684 printk("%s: set to minimum %d\n", __FUNCTION__
, max_segments
);
687 q
->max_hw_segments
= max_segments
;
690 EXPORT_SYMBOL(blk_queue_max_hw_segments
);
693 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
694 * @q: the request queue for the device
695 * @max_size: max size of segment in bytes
698 * Enables a low level driver to set an upper limit on the size of a
701 void blk_queue_max_segment_size(struct request_queue
*q
, unsigned int max_size
)
703 if (max_size
< PAGE_CACHE_SIZE
) {
704 max_size
= PAGE_CACHE_SIZE
;
705 printk("%s: set to minimum %d\n", __FUNCTION__
, max_size
);
708 q
->max_segment_size
= max_size
;
711 EXPORT_SYMBOL(blk_queue_max_segment_size
);
714 * blk_queue_hardsect_size - set hardware sector size for the queue
715 * @q: the request queue for the device
716 * @size: the hardware sector size, in bytes
719 * This should typically be set to the lowest possible sector size
720 * that the hardware can operate on (possible without reverting to
721 * even internal read-modify-write operations). Usually the default
722 * of 512 covers most hardware.
724 void blk_queue_hardsect_size(struct request_queue
*q
, unsigned short size
)
726 q
->hardsect_size
= size
;
729 EXPORT_SYMBOL(blk_queue_hardsect_size
);
732 * Returns the minimum that is _not_ zero, unless both are zero.
734 #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
737 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
738 * @t: the stacking driver (top)
739 * @b: the underlying device (bottom)
741 void blk_queue_stack_limits(struct request_queue
*t
, struct request_queue
*b
)
743 /* zero is "infinity" */
744 t
->max_sectors
= min_not_zero(t
->max_sectors
,b
->max_sectors
);
745 t
->max_hw_sectors
= min_not_zero(t
->max_hw_sectors
,b
->max_hw_sectors
);
747 t
->max_phys_segments
= min(t
->max_phys_segments
,b
->max_phys_segments
);
748 t
->max_hw_segments
= min(t
->max_hw_segments
,b
->max_hw_segments
);
749 t
->max_segment_size
= min(t
->max_segment_size
,b
->max_segment_size
);
750 t
->hardsect_size
= max(t
->hardsect_size
,b
->hardsect_size
);
751 if (!test_bit(QUEUE_FLAG_CLUSTER
, &b
->queue_flags
))
752 clear_bit(QUEUE_FLAG_CLUSTER
, &t
->queue_flags
);
755 EXPORT_SYMBOL(blk_queue_stack_limits
);
758 * blk_queue_segment_boundary - set boundary rules for segment merging
759 * @q: the request queue for the device
760 * @mask: the memory boundary mask
762 void blk_queue_segment_boundary(struct request_queue
*q
, unsigned long mask
)
764 if (mask
< PAGE_CACHE_SIZE
- 1) {
765 mask
= PAGE_CACHE_SIZE
- 1;
766 printk("%s: set to minimum %lx\n", __FUNCTION__
, mask
);
769 q
->seg_boundary_mask
= mask
;
772 EXPORT_SYMBOL(blk_queue_segment_boundary
);
775 * blk_queue_dma_alignment - set dma length and memory alignment
776 * @q: the request queue for the device
777 * @mask: alignment mask
780 * set required memory and length aligment for direct dma transactions.
781 * this is used when buiding direct io requests for the queue.
784 void blk_queue_dma_alignment(struct request_queue
*q
, int mask
)
786 q
->dma_alignment
= mask
;
789 EXPORT_SYMBOL(blk_queue_dma_alignment
);
792 * blk_queue_find_tag - find a request by its tag and queue
793 * @q: The request queue for the device
794 * @tag: The tag of the request
797 * Should be used when a device returns a tag and you want to match
800 * no locks need be held.
802 struct request
*blk_queue_find_tag(struct request_queue
*q
, int tag
)
804 return blk_map_queue_find_tag(q
->queue_tags
, tag
);
807 EXPORT_SYMBOL(blk_queue_find_tag
);
810 * __blk_free_tags - release a given set of tag maintenance info
811 * @bqt: the tag map to free
813 * Tries to free the specified @bqt@. Returns true if it was
814 * actually freed and false if there are still references using it
816 static int __blk_free_tags(struct blk_queue_tag
*bqt
)
820 retval
= atomic_dec_and_test(&bqt
->refcnt
);
823 BUG_ON(!list_empty(&bqt
->busy_list
));
825 kfree(bqt
->tag_index
);
826 bqt
->tag_index
= NULL
;
839 * __blk_queue_free_tags - release tag maintenance info
840 * @q: the request queue for the device
843 * blk_cleanup_queue() will take care of calling this function, if tagging
844 * has been used. So there's no need to call this directly.
846 static void __blk_queue_free_tags(struct request_queue
*q
)
848 struct blk_queue_tag
*bqt
= q
->queue_tags
;
853 __blk_free_tags(bqt
);
855 q
->queue_tags
= NULL
;
856 q
->queue_flags
&= ~(1 << QUEUE_FLAG_QUEUED
);
861 * blk_free_tags - release a given set of tag maintenance info
862 * @bqt: the tag map to free
864 * For externally managed @bqt@ frees the map. Callers of this
865 * function must guarantee to have released all the queues that
866 * might have been using this tag map.
868 void blk_free_tags(struct blk_queue_tag
*bqt
)
870 if (unlikely(!__blk_free_tags(bqt
)))
873 EXPORT_SYMBOL(blk_free_tags
);
876 * blk_queue_free_tags - release tag maintenance info
877 * @q: the request queue for the device
880 * This is used to disabled tagged queuing to a device, yet leave
883 void blk_queue_free_tags(struct request_queue
*q
)
885 clear_bit(QUEUE_FLAG_QUEUED
, &q
->queue_flags
);
888 EXPORT_SYMBOL(blk_queue_free_tags
);
891 init_tag_map(struct request_queue
*q
, struct blk_queue_tag
*tags
, int depth
)
893 struct request
**tag_index
;
894 unsigned long *tag_map
;
897 if (q
&& depth
> q
->nr_requests
* 2) {
898 depth
= q
->nr_requests
* 2;
899 printk(KERN_ERR
"%s: adjusted depth to %d\n",
900 __FUNCTION__
, depth
);
903 tag_index
= kzalloc(depth
* sizeof(struct request
*), GFP_ATOMIC
);
907 nr_ulongs
= ALIGN(depth
, BITS_PER_LONG
) / BITS_PER_LONG
;
908 tag_map
= kzalloc(nr_ulongs
* sizeof(unsigned long), GFP_ATOMIC
);
912 tags
->real_max_depth
= depth
;
913 tags
->max_depth
= depth
;
914 tags
->tag_index
= tag_index
;
915 tags
->tag_map
= tag_map
;
923 static struct blk_queue_tag
*__blk_queue_init_tags(struct request_queue
*q
,
926 struct blk_queue_tag
*tags
;
928 tags
= kmalloc(sizeof(struct blk_queue_tag
), GFP_ATOMIC
);
932 if (init_tag_map(q
, tags
, depth
))
935 INIT_LIST_HEAD(&tags
->busy_list
);
937 atomic_set(&tags
->refcnt
, 1);
945 * blk_init_tags - initialize the tag info for an external tag map
946 * @depth: the maximum queue depth supported
947 * @tags: the tag to use
949 struct blk_queue_tag
*blk_init_tags(int depth
)
951 return __blk_queue_init_tags(NULL
, depth
);
953 EXPORT_SYMBOL(blk_init_tags
);
956 * blk_queue_init_tags - initialize the queue tag info
957 * @q: the request queue for the device
958 * @depth: the maximum queue depth supported
959 * @tags: the tag to use
961 int blk_queue_init_tags(struct request_queue
*q
, int depth
,
962 struct blk_queue_tag
*tags
)
966 BUG_ON(tags
&& q
->queue_tags
&& tags
!= q
->queue_tags
);
968 if (!tags
&& !q
->queue_tags
) {
969 tags
= __blk_queue_init_tags(q
, depth
);
973 } else if (q
->queue_tags
) {
974 if ((rc
= blk_queue_resize_tags(q
, depth
)))
976 set_bit(QUEUE_FLAG_QUEUED
, &q
->queue_flags
);
979 atomic_inc(&tags
->refcnt
);
982 * assign it, all done
984 q
->queue_tags
= tags
;
985 q
->queue_flags
|= (1 << QUEUE_FLAG_QUEUED
);
992 EXPORT_SYMBOL(blk_queue_init_tags
);
995 * blk_queue_resize_tags - change the queueing depth
996 * @q: the request queue for the device
997 * @new_depth: the new max command queueing depth
1000 * Must be called with the queue lock held.
1002 int blk_queue_resize_tags(struct request_queue
*q
, int new_depth
)
1004 struct blk_queue_tag
*bqt
= q
->queue_tags
;
1005 struct request
**tag_index
;
1006 unsigned long *tag_map
;
1007 int max_depth
, nr_ulongs
;
1013 * if we already have large enough real_max_depth. just
1014 * adjust max_depth. *NOTE* as requests with tag value
1015 * between new_depth and real_max_depth can be in-flight, tag
1016 * map can not be shrunk blindly here.
1018 if (new_depth
<= bqt
->real_max_depth
) {
1019 bqt
->max_depth
= new_depth
;
1024 * Currently cannot replace a shared tag map with a new
1025 * one, so error out if this is the case
1027 if (atomic_read(&bqt
->refcnt
) != 1)
1031 * save the old state info, so we can copy it back
1033 tag_index
= bqt
->tag_index
;
1034 tag_map
= bqt
->tag_map
;
1035 max_depth
= bqt
->real_max_depth
;
1037 if (init_tag_map(q
, bqt
, new_depth
))
1040 memcpy(bqt
->tag_index
, tag_index
, max_depth
* sizeof(struct request
*));
1041 nr_ulongs
= ALIGN(max_depth
, BITS_PER_LONG
) / BITS_PER_LONG
;
1042 memcpy(bqt
->tag_map
, tag_map
, nr_ulongs
* sizeof(unsigned long));
1049 EXPORT_SYMBOL(blk_queue_resize_tags
);
1052 * blk_queue_end_tag - end tag operations for a request
1053 * @q: the request queue for the device
1054 * @rq: the request that has completed
1057 * Typically called when end_that_request_first() returns 0, meaning
1058 * all transfers have been done for a request. It's important to call
1059 * this function before end_that_request_last(), as that will put the
1060 * request back on the free list thus corrupting the internal tag list.
1063 * queue lock must be held.
1065 void blk_queue_end_tag(struct request_queue
*q
, struct request
*rq
)
1067 struct blk_queue_tag
*bqt
= q
->queue_tags
;
1072 if (unlikely(tag
>= bqt
->real_max_depth
))
1074 * This can happen after tag depth has been reduced.
1075 * FIXME: how about a warning or info message here?
1079 list_del_init(&rq
->queuelist
);
1080 rq
->cmd_flags
&= ~REQ_QUEUED
;
1083 if (unlikely(bqt
->tag_index
[tag
] == NULL
))
1084 printk(KERN_ERR
"%s: tag %d is missing\n",
1087 bqt
->tag_index
[tag
] = NULL
;
1090 * We use test_and_clear_bit's memory ordering properties here.
1091 * The tag_map bit acts as a lock for tag_index[bit], so we need
1092 * a barrer before clearing the bit (precisely: release semantics).
1093 * Could use clear_bit_unlock when it is merged.
1095 if (unlikely(!test_and_clear_bit(tag
, bqt
->tag_map
))) {
1096 printk(KERN_ERR
"%s: attempt to clear non-busy tag (%d)\n",
1104 EXPORT_SYMBOL(blk_queue_end_tag
);
1107 * blk_queue_start_tag - find a free tag and assign it
1108 * @q: the request queue for the device
1109 * @rq: the block request that needs tagging
1112 * This can either be used as a stand-alone helper, or possibly be
1113 * assigned as the queue &prep_rq_fn (in which case &struct request
1114 * automagically gets a tag assigned). Note that this function
1115 * assumes that any type of request can be queued! if this is not
1116 * true for your device, you must check the request type before
1117 * calling this function. The request will also be removed from
1118 * the request queue, so it's the drivers responsibility to readd
1119 * it if it should need to be restarted for some reason.
1122 * queue lock must be held.
1124 int blk_queue_start_tag(struct request_queue
*q
, struct request
*rq
)
1126 struct blk_queue_tag
*bqt
= q
->queue_tags
;
1129 if (unlikely((rq
->cmd_flags
& REQ_QUEUED
))) {
1131 "%s: request %p for device [%s] already tagged %d",
1133 rq
->rq_disk
? rq
->rq_disk
->disk_name
: "?", rq
->tag
);
1138 * Protect against shared tag maps, as we may not have exclusive
1139 * access to the tag map.
1142 tag
= find_first_zero_bit(bqt
->tag_map
, bqt
->max_depth
);
1143 if (tag
>= bqt
->max_depth
)
1146 } while (test_and_set_bit(tag
, bqt
->tag_map
));
1148 * We rely on test_and_set_bit providing lock memory ordering semantics
1149 * (could use test_and_set_bit_lock when it is merged).
1152 rq
->cmd_flags
|= REQ_QUEUED
;
1154 bqt
->tag_index
[tag
] = rq
;
1155 blkdev_dequeue_request(rq
);
1156 list_add(&rq
->queuelist
, &bqt
->busy_list
);
1161 EXPORT_SYMBOL(blk_queue_start_tag
);
1164 * blk_queue_invalidate_tags - invalidate all pending tags
1165 * @q: the request queue for the device
1168 * Hardware conditions may dictate a need to stop all pending requests.
1169 * In this case, we will safely clear the block side of the tag queue and
1170 * readd all requests to the request queue in the right order.
1173 * queue lock must be held.
1175 void blk_queue_invalidate_tags(struct request_queue
*q
)
1177 struct blk_queue_tag
*bqt
= q
->queue_tags
;
1178 struct list_head
*tmp
, *n
;
1181 list_for_each_safe(tmp
, n
, &bqt
->busy_list
) {
1182 rq
= list_entry_rq(tmp
);
1184 if (rq
->tag
== -1) {
1186 "%s: bad tag found on list\n", __FUNCTION__
);
1187 list_del_init(&rq
->queuelist
);
1188 rq
->cmd_flags
&= ~REQ_QUEUED
;
1190 blk_queue_end_tag(q
, rq
);
1192 rq
->cmd_flags
&= ~REQ_STARTED
;
1193 __elv_add_request(q
, rq
, ELEVATOR_INSERT_BACK
, 0);
1197 EXPORT_SYMBOL(blk_queue_invalidate_tags
);
1199 void blk_dump_rq_flags(struct request
*rq
, char *msg
)
1203 printk("%s: dev %s: type=%x, flags=%x\n", msg
,
1204 rq
->rq_disk
? rq
->rq_disk
->disk_name
: "?", rq
->cmd_type
,
1207 printk("\nsector %llu, nr/cnr %lu/%u\n", (unsigned long long)rq
->sector
,
1209 rq
->current_nr_sectors
);
1210 printk("bio %p, biotail %p, buffer %p, data %p, len %u\n", rq
->bio
, rq
->biotail
, rq
->buffer
, rq
->data
, rq
->data_len
);
1212 if (blk_pc_request(rq
)) {
1214 for (bit
= 0; bit
< sizeof(rq
->cmd
); bit
++)
1215 printk("%02x ", rq
->cmd
[bit
]);
1220 EXPORT_SYMBOL(blk_dump_rq_flags
);
1222 void blk_recount_segments(struct request_queue
*q
, struct bio
*bio
)
1225 struct bio
*nxt
= bio
->bi_next
;
1227 rq
.bio
= rq
.biotail
= bio
;
1228 bio
->bi_next
= NULL
;
1229 blk_recalc_rq_segments(&rq
);
1231 bio
->bi_phys_segments
= rq
.nr_phys_segments
;
1232 bio
->bi_hw_segments
= rq
.nr_hw_segments
;
1233 bio
->bi_flags
|= (1 << BIO_SEG_VALID
);
1235 EXPORT_SYMBOL(blk_recount_segments
);
1237 static void blk_recalc_rq_segments(struct request
*rq
)
1241 unsigned int phys_size
;
1242 unsigned int hw_size
;
1243 struct bio_vec
*bv
, *bvprv
= NULL
;
1249 int high
, highprv
= 1;
1250 struct request_queue
*q
= rq
->q
;
1255 cluster
= q
->queue_flags
& (1 << QUEUE_FLAG_CLUSTER
);
1256 hw_seg_size
= seg_size
= 0;
1257 phys_size
= hw_size
= nr_phys_segs
= nr_hw_segs
= 0;
1258 rq_for_each_bio(bio
, rq
)
1259 bio_for_each_segment(bv
, bio
, i
) {
1261 * the trick here is making sure that a high page is never
1262 * considered part of another segment, since that might
1263 * change with the bounce page.
1265 high
= page_to_pfn(bv
->bv_page
) > q
->bounce_pfn
;
1266 if (high
|| highprv
)
1267 goto new_hw_segment
;
1269 if (seg_size
+ bv
->bv_len
> q
->max_segment_size
)
1271 if (!BIOVEC_PHYS_MERGEABLE(bvprv
, bv
))
1273 if (!BIOVEC_SEG_BOUNDARY(q
, bvprv
, bv
))
1275 if (BIOVEC_VIRT_OVERSIZE(hw_seg_size
+ bv
->bv_len
))
1276 goto new_hw_segment
;
1278 seg_size
+= bv
->bv_len
;
1279 hw_seg_size
+= bv
->bv_len
;
1284 if (BIOVEC_VIRT_MERGEABLE(bvprv
, bv
) &&
1285 !BIOVEC_VIRT_OVERSIZE(hw_seg_size
+ bv
->bv_len
))
1286 hw_seg_size
+= bv
->bv_len
;
1289 if (nr_hw_segs
== 1 &&
1290 hw_seg_size
> rq
->bio
->bi_hw_front_size
)
1291 rq
->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
;
1302 if (nr_hw_segs
== 1 &&
1303 hw_seg_size
> rq
->bio
->bi_hw_front_size
)
1304 rq
->bio
->bi_hw_front_size
= hw_seg_size
;
1305 if (hw_seg_size
> rq
->biotail
->bi_hw_back_size
)
1306 rq
->biotail
->bi_hw_back_size
= hw_seg_size
;
1307 rq
->nr_phys_segments
= nr_phys_segs
;
1308 rq
->nr_hw_segments
= nr_hw_segs
;
1311 static int blk_phys_contig_segment(struct request_queue
*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(struct request_queue
*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_back_size
+ nxt
->bi_hw_front_size
))
1342 if (bio
->bi_hw_back_size
+ nxt
->bi_hw_front_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(struct request_queue
*q
, struct request
*rq
,
1353 struct scatterlist
*sg
)
1355 struct bio_vec
*bvec
, *bvprv
;
1357 int nsegs
, i
, cluster
;
1360 cluster
= q
->queue_flags
& (1 << QUEUE_FLAG_CLUSTER
);
1363 * for each bio in rq
1366 rq_for_each_bio(bio
, rq
) {
1368 * for each segment in bio
1370 bio_for_each_segment(bvec
, bio
, i
) {
1371 int nbytes
= bvec
->bv_len
;
1373 if (bvprv
&& cluster
) {
1374 if (sg
[nsegs
- 1].length
+ nbytes
> q
->max_segment_size
)
1377 if (!BIOVEC_PHYS_MERGEABLE(bvprv
, bvec
))
1379 if (!BIOVEC_SEG_BOUNDARY(q
, bvprv
, bvec
))
1382 sg
[nsegs
- 1].length
+= nbytes
;
1385 memset(&sg
[nsegs
],0,sizeof(struct scatterlist
));
1386 sg
[nsegs
].page
= bvec
->bv_page
;
1387 sg
[nsegs
].length
= nbytes
;
1388 sg
[nsegs
].offset
= bvec
->bv_offset
;
1393 } /* segments in bio */
1399 EXPORT_SYMBOL(blk_rq_map_sg
);
1402 * the standard queue merge functions, can be overridden with device
1403 * specific ones if so desired
1406 static inline int ll_new_mergeable(struct request_queue
*q
,
1407 struct request
*req
,
1410 int nr_phys_segs
= bio_phys_segments(q
, bio
);
1412 if (req
->nr_phys_segments
+ nr_phys_segs
> q
->max_phys_segments
) {
1413 req
->cmd_flags
|= REQ_NOMERGE
;
1414 if (req
== q
->last_merge
)
1415 q
->last_merge
= NULL
;
1420 * A hw segment is just getting larger, bump just the phys
1423 req
->nr_phys_segments
+= nr_phys_segs
;
1427 static inline int ll_new_hw_segment(struct request_queue
*q
,
1428 struct request
*req
,
1431 int nr_hw_segs
= bio_hw_segments(q
, bio
);
1432 int nr_phys_segs
= bio_phys_segments(q
, bio
);
1434 if (req
->nr_hw_segments
+ nr_hw_segs
> q
->max_hw_segments
1435 || req
->nr_phys_segments
+ nr_phys_segs
> q
->max_phys_segments
) {
1436 req
->cmd_flags
|= REQ_NOMERGE
;
1437 if (req
== q
->last_merge
)
1438 q
->last_merge
= NULL
;
1443 * This will form the start of a new hw segment. Bump both
1446 req
->nr_hw_segments
+= nr_hw_segs
;
1447 req
->nr_phys_segments
+= nr_phys_segs
;
1451 int ll_back_merge_fn(struct request_queue
*q
, struct request
*req
, struct bio
*bio
)
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
);
1487 EXPORT_SYMBOL(ll_back_merge_fn
);
1489 static int ll_front_merge_fn(struct request_queue
*q
, struct request
*req
,
1492 unsigned short max_sectors
;
1495 if (unlikely(blk_pc_request(req
)))
1496 max_sectors
= q
->max_hw_sectors
;
1498 max_sectors
= q
->max_sectors
;
1501 if (req
->nr_sectors
+ bio_sectors(bio
) > max_sectors
) {
1502 req
->cmd_flags
|= REQ_NOMERGE
;
1503 if (req
== q
->last_merge
)
1504 q
->last_merge
= NULL
;
1507 len
= bio
->bi_hw_back_size
+ req
->bio
->bi_hw_front_size
;
1508 if (unlikely(!bio_flagged(bio
, BIO_SEG_VALID
)))
1509 blk_recount_segments(q
, bio
);
1510 if (unlikely(!bio_flagged(req
->bio
, BIO_SEG_VALID
)))
1511 blk_recount_segments(q
, req
->bio
);
1512 if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio
), __BVEC_START(req
->bio
)) &&
1513 !BIOVEC_VIRT_OVERSIZE(len
)) {
1514 int mergeable
= ll_new_mergeable(q
, req
, bio
);
1517 if (bio
->bi_hw_segments
== 1)
1518 bio
->bi_hw_front_size
= len
;
1519 if (req
->nr_hw_segments
== 1)
1520 req
->biotail
->bi_hw_back_size
= len
;
1525 return ll_new_hw_segment(q
, req
, bio
);
1528 static int ll_merge_requests_fn(struct request_queue
*q
, struct request
*req
,
1529 struct request
*next
)
1531 int total_phys_segments
;
1532 int total_hw_segments
;
1535 * First check if the either of the requests are re-queued
1536 * requests. Can't merge them if they are.
1538 if (req
->special
|| next
->special
)
1542 * Will it become too large?
1544 if ((req
->nr_sectors
+ next
->nr_sectors
) > q
->max_sectors
)
1547 total_phys_segments
= req
->nr_phys_segments
+ next
->nr_phys_segments
;
1548 if (blk_phys_contig_segment(q
, req
->biotail
, next
->bio
))
1549 total_phys_segments
--;
1551 if (total_phys_segments
> q
->max_phys_segments
)
1554 total_hw_segments
= req
->nr_hw_segments
+ next
->nr_hw_segments
;
1555 if (blk_hw_contig_segment(q
, req
->biotail
, next
->bio
)) {
1556 int len
= req
->biotail
->bi_hw_back_size
+ next
->bio
->bi_hw_front_size
;
1558 * propagate the combined length to the end of the requests
1560 if (req
->nr_hw_segments
== 1)
1561 req
->bio
->bi_hw_front_size
= len
;
1562 if (next
->nr_hw_segments
== 1)
1563 next
->biotail
->bi_hw_back_size
= len
;
1564 total_hw_segments
--;
1567 if (total_hw_segments
> q
->max_hw_segments
)
1570 /* Merge is OK... */
1571 req
->nr_phys_segments
= total_phys_segments
;
1572 req
->nr_hw_segments
= total_hw_segments
;
1577 * "plug" the device if there are no outstanding requests: this will
1578 * force the transfer to start only after we have put all the requests
1581 * This is called with interrupts off and no requests on the queue and
1582 * with the queue lock held.
1584 void blk_plug_device(struct request_queue
*q
)
1586 WARN_ON(!irqs_disabled());
1589 * don't plug a stopped queue, it must be paired with blk_start_queue()
1590 * which will restart the queueing
1592 if (blk_queue_stopped(q
))
1595 if (!test_and_set_bit(QUEUE_FLAG_PLUGGED
, &q
->queue_flags
)) {
1596 mod_timer(&q
->unplug_timer
, jiffies
+ q
->unplug_delay
);
1597 blk_add_trace_generic(q
, NULL
, 0, BLK_TA_PLUG
);
1601 EXPORT_SYMBOL(blk_plug_device
);
1604 * remove the queue from the plugged list, if present. called with
1605 * queue lock held and interrupts disabled.
1607 int blk_remove_plug(struct request_queue
*q
)
1609 WARN_ON(!irqs_disabled());
1611 if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED
, &q
->queue_flags
))
1614 del_timer(&q
->unplug_timer
);
1618 EXPORT_SYMBOL(blk_remove_plug
);
1621 * remove the plug and let it rip..
1623 void __generic_unplug_device(struct request_queue
*q
)
1625 if (unlikely(blk_queue_stopped(q
)))
1628 if (!blk_remove_plug(q
))
1633 EXPORT_SYMBOL(__generic_unplug_device
);
1636 * generic_unplug_device - fire a request queue
1637 * @q: The &struct request_queue in question
1640 * Linux uses plugging to build bigger requests queues before letting
1641 * the device have at them. If a queue is plugged, the I/O scheduler
1642 * is still adding and merging requests on the queue. Once the queue
1643 * gets unplugged, the request_fn defined for the queue is invoked and
1644 * transfers started.
1646 void generic_unplug_device(struct request_queue
*q
)
1648 spin_lock_irq(q
->queue_lock
);
1649 __generic_unplug_device(q
);
1650 spin_unlock_irq(q
->queue_lock
);
1652 EXPORT_SYMBOL(generic_unplug_device
);
1654 static void blk_backing_dev_unplug(struct backing_dev_info
*bdi
,
1657 struct request_queue
*q
= bdi
->unplug_io_data
;
1660 * devices don't necessarily have an ->unplug_fn defined
1663 blk_add_trace_pdu_int(q
, BLK_TA_UNPLUG_IO
, NULL
,
1664 q
->rq
.count
[READ
] + q
->rq
.count
[WRITE
]);
1670 static void blk_unplug_work(struct work_struct
*work
)
1672 struct request_queue
*q
=
1673 container_of(work
, struct request_queue
, unplug_work
);
1675 blk_add_trace_pdu_int(q
, BLK_TA_UNPLUG_IO
, NULL
,
1676 q
->rq
.count
[READ
] + q
->rq
.count
[WRITE
]);
1681 static void blk_unplug_timeout(unsigned long data
)
1683 struct request_queue
*q
= (struct request_queue
*)data
;
1685 blk_add_trace_pdu_int(q
, BLK_TA_UNPLUG_TIMER
, NULL
,
1686 q
->rq
.count
[READ
] + q
->rq
.count
[WRITE
]);
1688 kblockd_schedule_work(&q
->unplug_work
);
1692 * blk_start_queue - restart a previously stopped queue
1693 * @q: The &struct request_queue in question
1696 * blk_start_queue() will clear the stop flag on the queue, and call
1697 * the request_fn for the queue if it was in a stopped state when
1698 * entered. Also see blk_stop_queue(). Queue lock must be held.
1700 void blk_start_queue(struct request_queue
*q
)
1702 WARN_ON(!irqs_disabled());
1704 clear_bit(QUEUE_FLAG_STOPPED
, &q
->queue_flags
);
1707 * one level of recursion is ok and is much faster than kicking
1708 * the unplug handling
1710 if (!test_and_set_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
)) {
1712 clear_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
);
1715 kblockd_schedule_work(&q
->unplug_work
);
1719 EXPORT_SYMBOL(blk_start_queue
);
1722 * blk_stop_queue - stop a queue
1723 * @q: The &struct request_queue in question
1726 * The Linux block layer assumes that a block driver will consume all
1727 * entries on the request queue when the request_fn strategy is called.
1728 * Often this will not happen, because of hardware limitations (queue
1729 * depth settings). If a device driver gets a 'queue full' response,
1730 * or if it simply chooses not to queue more I/O at one point, it can
1731 * call this function to prevent the request_fn from being called until
1732 * the driver has signalled it's ready to go again. This happens by calling
1733 * blk_start_queue() to restart queue operations. Queue lock must be held.
1735 void blk_stop_queue(struct request_queue
*q
)
1738 set_bit(QUEUE_FLAG_STOPPED
, &q
->queue_flags
);
1740 EXPORT_SYMBOL(blk_stop_queue
);
1743 * blk_sync_queue - cancel any pending callbacks on a queue
1747 * The block layer may perform asynchronous callback activity
1748 * on a queue, such as calling the unplug function after a timeout.
1749 * A block device may call blk_sync_queue to ensure that any
1750 * such activity is cancelled, thus allowing it to release resources
1751 * that the callbacks might use. The caller must already have made sure
1752 * that its ->make_request_fn will not re-add plugging prior to calling
1756 void blk_sync_queue(struct request_queue
*q
)
1758 del_timer_sync(&q
->unplug_timer
);
1760 EXPORT_SYMBOL(blk_sync_queue
);
1763 * blk_run_queue - run a single device queue
1764 * @q: The queue to run
1766 void blk_run_queue(struct request_queue
*q
)
1768 unsigned long flags
;
1770 spin_lock_irqsave(q
->queue_lock
, flags
);
1774 * Only recurse once to avoid overrunning the stack, let the unplug
1775 * handling reinvoke the handler shortly if we already got there.
1777 if (!elv_queue_empty(q
)) {
1778 if (!test_and_set_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
)) {
1780 clear_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
);
1783 kblockd_schedule_work(&q
->unplug_work
);
1787 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1789 EXPORT_SYMBOL(blk_run_queue
);
1792 * blk_cleanup_queue: - release a &struct request_queue when it is no longer needed
1793 * @kobj: the kobj belonging of the request queue to be released
1796 * blk_cleanup_queue is the pair to blk_init_queue() or
1797 * blk_queue_make_request(). It should be called when a request queue is
1798 * being released; typically when a block device is being de-registered.
1799 * Currently, its primary task it to free all the &struct request
1800 * structures that were allocated to the queue and the queue itself.
1803 * Hopefully the low level driver will have finished any
1804 * outstanding requests first...
1806 static void blk_release_queue(struct kobject
*kobj
)
1808 struct request_queue
*q
=
1809 container_of(kobj
, struct request_queue
, kobj
);
1810 struct request_list
*rl
= &q
->rq
;
1815 mempool_destroy(rl
->rq_pool
);
1818 __blk_queue_free_tags(q
);
1820 blk_trace_shutdown(q
);
1822 kmem_cache_free(requestq_cachep
, q
);
1825 void blk_put_queue(struct request_queue
*q
)
1827 kobject_put(&q
->kobj
);
1829 EXPORT_SYMBOL(blk_put_queue
);
1831 void blk_cleanup_queue(struct request_queue
* q
)
1833 mutex_lock(&q
->sysfs_lock
);
1834 set_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
);
1835 mutex_unlock(&q
->sysfs_lock
);
1838 elevator_exit(q
->elevator
);
1843 EXPORT_SYMBOL(blk_cleanup_queue
);
1845 static int blk_init_free_list(struct request_queue
*q
)
1847 struct request_list
*rl
= &q
->rq
;
1849 rl
->count
[READ
] = rl
->count
[WRITE
] = 0;
1850 rl
->starved
[READ
] = rl
->starved
[WRITE
] = 0;
1852 init_waitqueue_head(&rl
->wait
[READ
]);
1853 init_waitqueue_head(&rl
->wait
[WRITE
]);
1855 rl
->rq_pool
= mempool_create_node(BLKDEV_MIN_RQ
, mempool_alloc_slab
,
1856 mempool_free_slab
, request_cachep
, q
->node
);
1864 struct request_queue
*blk_alloc_queue(gfp_t gfp_mask
)
1866 return blk_alloc_queue_node(gfp_mask
, -1);
1868 EXPORT_SYMBOL(blk_alloc_queue
);
1870 static struct kobj_type queue_ktype
;
1872 struct request_queue
*blk_alloc_queue_node(gfp_t gfp_mask
, int node_id
)
1874 struct request_queue
*q
;
1876 q
= kmem_cache_alloc_node(requestq_cachep
,
1877 gfp_mask
| __GFP_ZERO
, node_id
);
1881 init_timer(&q
->unplug_timer
);
1883 snprintf(q
->kobj
.name
, KOBJ_NAME_LEN
, "%s", "queue");
1884 q
->kobj
.ktype
= &queue_ktype
;
1885 kobject_init(&q
->kobj
);
1887 q
->backing_dev_info
.unplug_io_fn
= blk_backing_dev_unplug
;
1888 q
->backing_dev_info
.unplug_io_data
= q
;
1890 mutex_init(&q
->sysfs_lock
);
1894 EXPORT_SYMBOL(blk_alloc_queue_node
);
1897 * blk_init_queue - prepare a request queue for use with a block device
1898 * @rfn: The function to be called to process requests that have been
1899 * placed on the queue.
1900 * @lock: Request queue spin lock
1903 * If a block device wishes to use the standard request handling procedures,
1904 * which sorts requests and coalesces adjacent requests, then it must
1905 * call blk_init_queue(). The function @rfn will be called when there
1906 * are requests on the queue that need to be processed. If the device
1907 * supports plugging, then @rfn may not be called immediately when requests
1908 * are available on the queue, but may be called at some time later instead.
1909 * Plugged queues are generally unplugged when a buffer belonging to one
1910 * of the requests on the queue is needed, or due to memory pressure.
1912 * @rfn is not required, or even expected, to remove all requests off the
1913 * queue, but only as many as it can handle at a time. If it does leave
1914 * requests on the queue, it is responsible for arranging that the requests
1915 * get dealt with eventually.
1917 * The queue spin lock must be held while manipulating the requests on the
1918 * request queue; this lock will be taken also from interrupt context, so irq
1919 * disabling is needed for it.
1921 * Function returns a pointer to the initialized request queue, or NULL if
1922 * it didn't succeed.
1925 * blk_init_queue() must be paired with a blk_cleanup_queue() call
1926 * when the block device is deactivated (such as at module unload).
1929 struct request_queue
*blk_init_queue(request_fn_proc
*rfn
, spinlock_t
*lock
)
1931 return blk_init_queue_node(rfn
, lock
, -1);
1933 EXPORT_SYMBOL(blk_init_queue
);
1935 struct request_queue
*
1936 blk_init_queue_node(request_fn_proc
*rfn
, spinlock_t
*lock
, int node_id
)
1938 struct request_queue
*q
= blk_alloc_queue_node(GFP_KERNEL
, node_id
);
1944 if (blk_init_free_list(q
)) {
1945 kmem_cache_free(requestq_cachep
, q
);
1950 * if caller didn't supply a lock, they get per-queue locking with
1954 spin_lock_init(&q
->__queue_lock
);
1955 lock
= &q
->__queue_lock
;
1958 q
->request_fn
= rfn
;
1959 q
->prep_rq_fn
= NULL
;
1960 q
->unplug_fn
= generic_unplug_device
;
1961 q
->queue_flags
= (1 << QUEUE_FLAG_CLUSTER
);
1962 q
->queue_lock
= lock
;
1964 blk_queue_segment_boundary(q
, 0xffffffff);
1966 blk_queue_make_request(q
, __make_request
);
1967 blk_queue_max_segment_size(q
, MAX_SEGMENT_SIZE
);
1969 blk_queue_max_hw_segments(q
, MAX_HW_SEGMENTS
);
1970 blk_queue_max_phys_segments(q
, MAX_PHYS_SEGMENTS
);
1972 q
->sg_reserved_size
= INT_MAX
;
1977 if (!elevator_init(q
, NULL
)) {
1978 blk_queue_congestion_threshold(q
);
1985 EXPORT_SYMBOL(blk_init_queue_node
);
1987 int blk_get_queue(struct request_queue
*q
)
1989 if (likely(!test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
))) {
1990 kobject_get(&q
->kobj
);
1997 EXPORT_SYMBOL(blk_get_queue
);
1999 static inline void blk_free_request(struct request_queue
*q
, struct request
*rq
)
2001 if (rq
->cmd_flags
& REQ_ELVPRIV
)
2002 elv_put_request(q
, rq
);
2003 mempool_free(rq
, q
->rq
.rq_pool
);
2006 static struct request
*
2007 blk_alloc_request(struct request_queue
*q
, int rw
, int priv
, gfp_t gfp_mask
)
2009 struct request
*rq
= mempool_alloc(q
->rq
.rq_pool
, gfp_mask
);
2015 * first three bits are identical in rq->cmd_flags and bio->bi_rw,
2016 * see bio.h and blkdev.h
2018 rq
->cmd_flags
= rw
| REQ_ALLOCED
;
2021 if (unlikely(elv_set_request(q
, rq
, gfp_mask
))) {
2022 mempool_free(rq
, q
->rq
.rq_pool
);
2025 rq
->cmd_flags
|= REQ_ELVPRIV
;
2032 * ioc_batching returns true if the ioc is a valid batching request and
2033 * should be given priority access to a request.
2035 static inline int ioc_batching(struct request_queue
*q
, struct io_context
*ioc
)
2041 * Make sure the process is able to allocate at least 1 request
2042 * even if the batch times out, otherwise we could theoretically
2045 return ioc
->nr_batch_requests
== q
->nr_batching
||
2046 (ioc
->nr_batch_requests
> 0
2047 && time_before(jiffies
, ioc
->last_waited
+ BLK_BATCH_TIME
));
2051 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
2052 * will cause the process to be a "batcher" on all queues in the system. This
2053 * is the behaviour we want though - once it gets a wakeup it should be given
2056 static void ioc_set_batching(struct request_queue
*q
, struct io_context
*ioc
)
2058 if (!ioc
|| ioc_batching(q
, ioc
))
2061 ioc
->nr_batch_requests
= q
->nr_batching
;
2062 ioc
->last_waited
= jiffies
;
2065 static void __freed_request(struct request_queue
*q
, int rw
)
2067 struct request_list
*rl
= &q
->rq
;
2069 if (rl
->count
[rw
] < queue_congestion_off_threshold(q
))
2070 blk_clear_queue_congested(q
, rw
);
2072 if (rl
->count
[rw
] + 1 <= q
->nr_requests
) {
2073 if (waitqueue_active(&rl
->wait
[rw
]))
2074 wake_up(&rl
->wait
[rw
]);
2076 blk_clear_queue_full(q
, rw
);
2081 * A request has just been released. Account for it, update the full and
2082 * congestion status, wake up any waiters. Called under q->queue_lock.
2084 static void freed_request(struct request_queue
*q
, int rw
, int priv
)
2086 struct request_list
*rl
= &q
->rq
;
2092 __freed_request(q
, rw
);
2094 if (unlikely(rl
->starved
[rw
^ 1]))
2095 __freed_request(q
, rw
^ 1);
2098 #define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist)
2100 * Get a free request, queue_lock must be held.
2101 * Returns NULL on failure, with queue_lock held.
2102 * Returns !NULL on success, with queue_lock *not held*.
2104 static struct request
*get_request(struct request_queue
*q
, int rw_flags
,
2105 struct bio
*bio
, gfp_t gfp_mask
)
2107 struct request
*rq
= NULL
;
2108 struct request_list
*rl
= &q
->rq
;
2109 struct io_context
*ioc
= NULL
;
2110 const int rw
= rw_flags
& 0x01;
2111 int may_queue
, priv
;
2113 may_queue
= elv_may_queue(q
, rw_flags
);
2114 if (may_queue
== ELV_MQUEUE_NO
)
2117 if (rl
->count
[rw
]+1 >= queue_congestion_on_threshold(q
)) {
2118 if (rl
->count
[rw
]+1 >= q
->nr_requests
) {
2119 ioc
= current_io_context(GFP_ATOMIC
, q
->node
);
2121 * The queue will fill after this allocation, so set
2122 * it as full, and mark this process as "batching".
2123 * This process will be allowed to complete a batch of
2124 * requests, others will be blocked.
2126 if (!blk_queue_full(q
, rw
)) {
2127 ioc_set_batching(q
, ioc
);
2128 blk_set_queue_full(q
, rw
);
2130 if (may_queue
!= ELV_MQUEUE_MUST
2131 && !ioc_batching(q
, ioc
)) {
2133 * The queue is full and the allocating
2134 * process is not a "batcher", and not
2135 * exempted by the IO scheduler
2141 blk_set_queue_congested(q
, rw
);
2145 * Only allow batching queuers to allocate up to 50% over the defined
2146 * limit of requests, otherwise we could have thousands of requests
2147 * allocated with any setting of ->nr_requests
2149 if (rl
->count
[rw
] >= (3 * q
->nr_requests
/ 2))
2153 rl
->starved
[rw
] = 0;
2155 priv
= !test_bit(QUEUE_FLAG_ELVSWITCH
, &q
->queue_flags
);
2159 spin_unlock_irq(q
->queue_lock
);
2161 rq
= blk_alloc_request(q
, rw_flags
, priv
, gfp_mask
);
2162 if (unlikely(!rq
)) {
2164 * Allocation failed presumably due to memory. Undo anything
2165 * we might have messed up.
2167 * Allocating task should really be put onto the front of the
2168 * wait queue, but this is pretty rare.
2170 spin_lock_irq(q
->queue_lock
);
2171 freed_request(q
, rw
, priv
);
2174 * in the very unlikely event that allocation failed and no
2175 * requests for this direction was pending, mark us starved
2176 * so that freeing of a request in the other direction will
2177 * notice us. another possible fix would be to split the
2178 * rq mempool into READ and WRITE
2181 if (unlikely(rl
->count
[rw
] == 0))
2182 rl
->starved
[rw
] = 1;
2188 * ioc may be NULL here, and ioc_batching will be false. That's
2189 * OK, if the queue is under the request limit then requests need
2190 * not count toward the nr_batch_requests limit. There will always
2191 * be some limit enforced by BLK_BATCH_TIME.
2193 if (ioc_batching(q
, ioc
))
2194 ioc
->nr_batch_requests
--;
2198 blk_add_trace_generic(q
, bio
, rw
, BLK_TA_GETRQ
);
2204 * No available requests for this queue, unplug the device and wait for some
2205 * requests to become available.
2207 * Called with q->queue_lock held, and returns with it unlocked.
2209 static struct request
*get_request_wait(struct request_queue
*q
, int rw_flags
,
2212 const int rw
= rw_flags
& 0x01;
2215 rq
= get_request(q
, rw_flags
, bio
, GFP_NOIO
);
2218 struct request_list
*rl
= &q
->rq
;
2220 prepare_to_wait_exclusive(&rl
->wait
[rw
], &wait
,
2221 TASK_UNINTERRUPTIBLE
);
2223 rq
= get_request(q
, rw_flags
, bio
, GFP_NOIO
);
2226 struct io_context
*ioc
;
2228 blk_add_trace_generic(q
, bio
, rw
, BLK_TA_SLEEPRQ
);
2230 __generic_unplug_device(q
);
2231 spin_unlock_irq(q
->queue_lock
);
2235 * After sleeping, we become a "batching" process and
2236 * will be able to allocate at least one request, and
2237 * up to a big batch of them for a small period time.
2238 * See ioc_batching, ioc_set_batching
2240 ioc
= current_io_context(GFP_NOIO
, q
->node
);
2241 ioc_set_batching(q
, ioc
);
2243 spin_lock_irq(q
->queue_lock
);
2245 finish_wait(&rl
->wait
[rw
], &wait
);
2251 struct request
*blk_get_request(struct request_queue
*q
, int rw
, gfp_t gfp_mask
)
2255 BUG_ON(rw
!= READ
&& rw
!= WRITE
);
2257 spin_lock_irq(q
->queue_lock
);
2258 if (gfp_mask
& __GFP_WAIT
) {
2259 rq
= get_request_wait(q
, rw
, NULL
);
2261 rq
= get_request(q
, rw
, NULL
, gfp_mask
);
2263 spin_unlock_irq(q
->queue_lock
);
2265 /* q->queue_lock is unlocked at this point */
2269 EXPORT_SYMBOL(blk_get_request
);
2272 * blk_start_queueing - initiate dispatch of requests to device
2273 * @q: request queue to kick into gear
2275 * This is basically a helper to remove the need to know whether a queue
2276 * is plugged or not if someone just wants to initiate dispatch of requests
2279 * The queue lock must be held with interrupts disabled.
2281 void blk_start_queueing(struct request_queue
*q
)
2283 if (!blk_queue_plugged(q
))
2286 __generic_unplug_device(q
);
2288 EXPORT_SYMBOL(blk_start_queueing
);
2291 * blk_requeue_request - put a request back on queue
2292 * @q: request queue where request should be inserted
2293 * @rq: request to be inserted
2296 * Drivers often keep queueing requests until the hardware cannot accept
2297 * more, when that condition happens we need to put the request back
2298 * on the queue. Must be called with queue lock held.
2300 void blk_requeue_request(struct request_queue
*q
, struct request
*rq
)
2302 blk_add_trace_rq(q
, rq
, BLK_TA_REQUEUE
);
2304 if (blk_rq_tagged(rq
))
2305 blk_queue_end_tag(q
, rq
);
2307 elv_requeue_request(q
, rq
);
2310 EXPORT_SYMBOL(blk_requeue_request
);
2313 * blk_insert_request - insert a special request in to a request queue
2314 * @q: request queue where request should be inserted
2315 * @rq: request to be inserted
2316 * @at_head: insert request at head or tail of queue
2317 * @data: private data
2320 * Many block devices need to execute commands asynchronously, so they don't
2321 * block the whole kernel from preemption during request execution. This is
2322 * accomplished normally by inserting aritficial requests tagged as
2323 * REQ_SPECIAL in to the corresponding request queue, and letting them be
2324 * scheduled for actual execution by the request queue.
2326 * We have the option of inserting the head or the tail of the queue.
2327 * Typically we use the tail for new ioctls and so forth. We use the head
2328 * of the queue for things like a QUEUE_FULL message from a device, or a
2329 * host that is unable to accept a particular command.
2331 void blk_insert_request(struct request_queue
*q
, struct request
*rq
,
2332 int at_head
, void *data
)
2334 int where
= at_head
? ELEVATOR_INSERT_FRONT
: ELEVATOR_INSERT_BACK
;
2335 unsigned long flags
;
2338 * tell I/O scheduler that this isn't a regular read/write (ie it
2339 * must not attempt merges on this) and that it acts as a soft
2342 rq
->cmd_type
= REQ_TYPE_SPECIAL
;
2343 rq
->cmd_flags
|= REQ_SOFTBARRIER
;
2347 spin_lock_irqsave(q
->queue_lock
, flags
);
2350 * If command is tagged, release the tag
2352 if (blk_rq_tagged(rq
))
2353 blk_queue_end_tag(q
, rq
);
2355 drive_stat_acct(rq
, rq
->nr_sectors
, 1);
2356 __elv_add_request(q
, rq
, where
, 0);
2357 blk_start_queueing(q
);
2358 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2361 EXPORT_SYMBOL(blk_insert_request
);
2363 static int __blk_rq_unmap_user(struct bio
*bio
)
2368 if (bio_flagged(bio
, BIO_USER_MAPPED
))
2369 bio_unmap_user(bio
);
2371 ret
= bio_uncopy_user(bio
);
2377 static int __blk_rq_map_user(struct request_queue
*q
, struct request
*rq
,
2378 void __user
*ubuf
, unsigned int len
)
2380 unsigned long uaddr
;
2381 struct bio
*bio
, *orig_bio
;
2384 reading
= rq_data_dir(rq
) == READ
;
2387 * if alignment requirement is satisfied, map in user pages for
2388 * direct dma. else, set up kernel bounce buffers
2390 uaddr
= (unsigned long) ubuf
;
2391 if (!(uaddr
& queue_dma_alignment(q
)) && !(len
& queue_dma_alignment(q
)))
2392 bio
= bio_map_user(q
, NULL
, uaddr
, len
, reading
);
2394 bio
= bio_copy_user(q
, uaddr
, len
, reading
);
2397 return PTR_ERR(bio
);
2400 blk_queue_bounce(q
, &bio
);
2403 * We link the bounce buffer in and could have to traverse it
2404 * later so we have to get a ref to prevent it from being freed
2409 blk_rq_bio_prep(q
, rq
, bio
);
2410 else if (!ll_back_merge_fn(q
, rq
, bio
)) {
2414 rq
->biotail
->bi_next
= bio
;
2417 rq
->data_len
+= bio
->bi_size
;
2420 return bio
->bi_size
;
2423 /* if it was boucned we must call the end io function */
2424 bio_endio(bio
, bio
->bi_size
, 0);
2425 __blk_rq_unmap_user(orig_bio
);
2431 * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
2432 * @q: request queue where request should be inserted
2433 * @rq: request structure to fill
2434 * @ubuf: the user buffer
2435 * @len: length of user data
2438 * Data will be mapped directly for zero copy io, if possible. Otherwise
2439 * a kernel bounce buffer is used.
2441 * A matching blk_rq_unmap_user() must be issued at the end of io, while
2442 * still in process context.
2444 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
2445 * before being submitted to the device, as pages mapped may be out of
2446 * reach. It's the callers responsibility to make sure this happens. The
2447 * original bio must be passed back in to blk_rq_unmap_user() for proper
2450 int blk_rq_map_user(struct request_queue
*q
, struct request
*rq
,
2451 void __user
*ubuf
, unsigned long len
)
2453 unsigned long bytes_read
= 0;
2454 struct bio
*bio
= NULL
;
2457 if (len
> (q
->max_hw_sectors
<< 9))
2462 while (bytes_read
!= len
) {
2463 unsigned long map_len
, end
, start
;
2465 map_len
= min_t(unsigned long, len
- bytes_read
, BIO_MAX_SIZE
);
2466 end
= ((unsigned long)ubuf
+ map_len
+ PAGE_SIZE
- 1)
2468 start
= (unsigned long)ubuf
>> PAGE_SHIFT
;
2471 * A bad offset could cause us to require BIO_MAX_PAGES + 1
2472 * pages. If this happens we just lower the requested
2473 * mapping len by a page so that we can fit
2475 if (end
- start
> BIO_MAX_PAGES
)
2476 map_len
-= PAGE_SIZE
;
2478 ret
= __blk_rq_map_user(q
, rq
, ubuf
, map_len
);
2487 rq
->buffer
= rq
->data
= NULL
;
2490 blk_rq_unmap_user(bio
);
2494 EXPORT_SYMBOL(blk_rq_map_user
);
2497 * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage
2498 * @q: request queue where request should be inserted
2499 * @rq: request to map data to
2500 * @iov: pointer to the iovec
2501 * @iov_count: number of elements in the iovec
2502 * @len: I/O byte count
2505 * Data will be mapped directly for zero copy io, if possible. Otherwise
2506 * a kernel bounce buffer is used.
2508 * A matching blk_rq_unmap_user() must be issued at the end of io, while
2509 * still in process context.
2511 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
2512 * before being submitted to the device, as pages mapped may be out of
2513 * reach. It's the callers responsibility to make sure this happens. The
2514 * original bio must be passed back in to blk_rq_unmap_user() for proper
2517 int blk_rq_map_user_iov(struct request_queue
*q
, struct request
*rq
,
2518 struct sg_iovec
*iov
, int iov_count
, unsigned int len
)
2522 if (!iov
|| iov_count
<= 0)
2525 /* we don't allow misaligned data like bio_map_user() does. If the
2526 * user is using sg, they're expected to know the alignment constraints
2527 * and respect them accordingly */
2528 bio
= bio_map_user_iov(q
, NULL
, iov
, iov_count
, rq_data_dir(rq
)== READ
);
2530 return PTR_ERR(bio
);
2532 if (bio
->bi_size
!= len
) {
2533 bio_endio(bio
, bio
->bi_size
, 0);
2534 bio_unmap_user(bio
);
2539 blk_rq_bio_prep(q
, rq
, bio
);
2540 rq
->buffer
= rq
->data
= NULL
;
2544 EXPORT_SYMBOL(blk_rq_map_user_iov
);
2547 * blk_rq_unmap_user - unmap a request with user data
2548 * @bio: start of bio list
2551 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must
2552 * supply the original rq->bio from the blk_rq_map_user() return, since
2553 * the io completion may have changed rq->bio.
2555 int blk_rq_unmap_user(struct bio
*bio
)
2557 struct bio
*mapped_bio
;
2562 if (unlikely(bio_flagged(bio
, BIO_BOUNCED
)))
2563 mapped_bio
= bio
->bi_private
;
2565 ret2
= __blk_rq_unmap_user(mapped_bio
);
2571 bio_put(mapped_bio
);
2577 EXPORT_SYMBOL(blk_rq_unmap_user
);
2580 * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage
2581 * @q: request queue where request should be inserted
2582 * @rq: request to fill
2583 * @kbuf: the kernel buffer
2584 * @len: length of user data
2585 * @gfp_mask: memory allocation flags
2587 int blk_rq_map_kern(struct request_queue
*q
, struct request
*rq
, void *kbuf
,
2588 unsigned int len
, gfp_t gfp_mask
)
2592 if (len
> (q
->max_hw_sectors
<< 9))
2597 bio
= bio_map_kern(q
, kbuf
, len
, gfp_mask
);
2599 return PTR_ERR(bio
);
2601 if (rq_data_dir(rq
) == WRITE
)
2602 bio
->bi_rw
|= (1 << BIO_RW
);
2604 blk_rq_bio_prep(q
, rq
, bio
);
2605 blk_queue_bounce(q
, &rq
->bio
);
2606 rq
->buffer
= rq
->data
= NULL
;
2610 EXPORT_SYMBOL(blk_rq_map_kern
);
2613 * blk_execute_rq_nowait - insert a request into queue for execution
2614 * @q: queue to insert the request in
2615 * @bd_disk: matching gendisk
2616 * @rq: request to insert
2617 * @at_head: insert request at head or tail of queue
2618 * @done: I/O completion handler
2621 * Insert a fully prepared request at the back of the io scheduler queue
2622 * for execution. Don't wait for completion.
2624 void blk_execute_rq_nowait(struct request_queue
*q
, struct gendisk
*bd_disk
,
2625 struct request
*rq
, int at_head
,
2628 int where
= at_head
? ELEVATOR_INSERT_FRONT
: ELEVATOR_INSERT_BACK
;
2630 rq
->rq_disk
= bd_disk
;
2631 rq
->cmd_flags
|= REQ_NOMERGE
;
2633 WARN_ON(irqs_disabled());
2634 spin_lock_irq(q
->queue_lock
);
2635 __elv_add_request(q
, rq
, where
, 1);
2636 __generic_unplug_device(q
);
2637 spin_unlock_irq(q
->queue_lock
);
2639 EXPORT_SYMBOL_GPL(blk_execute_rq_nowait
);
2642 * blk_execute_rq - insert a request into queue for execution
2643 * @q: queue to insert the request in
2644 * @bd_disk: matching gendisk
2645 * @rq: request to insert
2646 * @at_head: insert request at head or tail of queue
2649 * Insert a fully prepared request at the back of the io scheduler queue
2650 * for execution and wait for completion.
2652 int blk_execute_rq(struct request_queue
*q
, struct gendisk
*bd_disk
,
2653 struct request
*rq
, int at_head
)
2655 DECLARE_COMPLETION_ONSTACK(wait
);
2656 char sense
[SCSI_SENSE_BUFFERSIZE
];
2660 * we need an extra reference to the request, so we can look at
2661 * it after io completion
2666 memset(sense
, 0, sizeof(sense
));
2671 rq
->end_io_data
= &wait
;
2672 blk_execute_rq_nowait(q
, bd_disk
, rq
, at_head
, blk_end_sync_rq
);
2673 wait_for_completion(&wait
);
2681 EXPORT_SYMBOL(blk_execute_rq
);
2684 * blkdev_issue_flush - queue a flush
2685 * @bdev: blockdev to issue flush for
2686 * @error_sector: error sector
2689 * Issue a flush for the block device in question. Caller can supply
2690 * room for storing the error offset in case of a flush error, if they
2691 * wish to. Caller must run wait_for_completion() on its own.
2693 int blkdev_issue_flush(struct block_device
*bdev
, sector_t
*error_sector
)
2695 struct request_queue
*q
;
2697 if (bdev
->bd_disk
== NULL
)
2700 q
= bdev_get_queue(bdev
);
2703 if (!q
->issue_flush_fn
)
2706 return q
->issue_flush_fn(q
, bdev
->bd_disk
, error_sector
);
2709 EXPORT_SYMBOL(blkdev_issue_flush
);
2711 static void drive_stat_acct(struct request
*rq
, int nr_sectors
, int new_io
)
2713 int rw
= rq_data_dir(rq
);
2715 if (!blk_fs_request(rq
) || !rq
->rq_disk
)
2719 __disk_stat_inc(rq
->rq_disk
, merges
[rw
]);
2721 disk_round_stats(rq
->rq_disk
);
2722 rq
->rq_disk
->in_flight
++;
2727 * add-request adds a request to the linked list.
2728 * queue lock is held and interrupts disabled, as we muck with the
2729 * request queue list.
2731 static inline void add_request(struct request_queue
* q
, struct request
* req
)
2733 drive_stat_acct(req
, req
->nr_sectors
, 1);
2736 * elevator indicated where it wants this request to be
2737 * inserted at elevator_merge time
2739 __elv_add_request(q
, req
, ELEVATOR_INSERT_SORT
, 0);
2743 * disk_round_stats() - Round off the performance stats on a struct
2746 * The average IO queue length and utilisation statistics are maintained
2747 * by observing the current state of the queue length and the amount of
2748 * time it has been in this state for.
2750 * Normally, that accounting is done on IO completion, but that can result
2751 * in more than a second's worth of IO being accounted for within any one
2752 * second, leading to >100% utilisation. To deal with that, we call this
2753 * function to do a round-off before returning the results when reading
2754 * /proc/diskstats. This accounts immediately for all queue usage up to
2755 * the current jiffies and restarts the counters again.
2757 void disk_round_stats(struct gendisk
*disk
)
2759 unsigned long now
= jiffies
;
2761 if (now
== disk
->stamp
)
2764 if (disk
->in_flight
) {
2765 __disk_stat_add(disk
, time_in_queue
,
2766 disk
->in_flight
* (now
- disk
->stamp
));
2767 __disk_stat_add(disk
, io_ticks
, (now
- disk
->stamp
));
2772 EXPORT_SYMBOL_GPL(disk_round_stats
);
2775 * queue lock must be held
2777 void __blk_put_request(struct request_queue
*q
, struct request
*req
)
2781 if (unlikely(--req
->ref_count
))
2784 elv_completed_request(q
, req
);
2787 * Request may not have originated from ll_rw_blk. if not,
2788 * it didn't come out of our reserved rq pools
2790 if (req
->cmd_flags
& REQ_ALLOCED
) {
2791 int rw
= rq_data_dir(req
);
2792 int priv
= req
->cmd_flags
& REQ_ELVPRIV
;
2794 BUG_ON(!list_empty(&req
->queuelist
));
2795 BUG_ON(!hlist_unhashed(&req
->hash
));
2797 blk_free_request(q
, req
);
2798 freed_request(q
, rw
, priv
);
2802 EXPORT_SYMBOL_GPL(__blk_put_request
);
2804 void blk_put_request(struct request
*req
)
2806 unsigned long flags
;
2807 struct request_queue
*q
= req
->q
;
2810 * Gee, IDE calls in w/ NULL q. Fix IDE and remove the
2811 * following if (q) test.
2814 spin_lock_irqsave(q
->queue_lock
, flags
);
2815 __blk_put_request(q
, req
);
2816 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2820 EXPORT_SYMBOL(blk_put_request
);
2823 * blk_end_sync_rq - executes a completion event on a request
2824 * @rq: request to complete
2825 * @error: end io status of the request
2827 void blk_end_sync_rq(struct request
*rq
, int error
)
2829 struct completion
*waiting
= rq
->end_io_data
;
2831 rq
->end_io_data
= NULL
;
2832 __blk_put_request(rq
->q
, rq
);
2835 * complete last, if this is a stack request the process (and thus
2836 * the rq pointer) could be invalid right after this complete()
2840 EXPORT_SYMBOL(blk_end_sync_rq
);
2843 * Has to be called with the request spinlock acquired
2845 static int attempt_merge(struct request_queue
*q
, struct request
*req
,
2846 struct request
*next
)
2848 if (!rq_mergeable(req
) || !rq_mergeable(next
))
2854 if (req
->sector
+ req
->nr_sectors
!= next
->sector
)
2857 if (rq_data_dir(req
) != rq_data_dir(next
)
2858 || req
->rq_disk
!= next
->rq_disk
2863 * If we are allowed to merge, then append bio list
2864 * from next to rq and release next. merge_requests_fn
2865 * will have updated segment counts, update sector
2868 if (!ll_merge_requests_fn(q
, req
, next
))
2872 * At this point we have either done a back merge
2873 * or front merge. We need the smaller start_time of
2874 * the merged requests to be the current request
2875 * for accounting purposes.
2877 if (time_after(req
->start_time
, next
->start_time
))
2878 req
->start_time
= next
->start_time
;
2880 req
->biotail
->bi_next
= next
->bio
;
2881 req
->biotail
= next
->biotail
;
2883 req
->nr_sectors
= req
->hard_nr_sectors
+= next
->hard_nr_sectors
;
2885 elv_merge_requests(q
, req
, next
);
2888 disk_round_stats(req
->rq_disk
);
2889 req
->rq_disk
->in_flight
--;
2892 req
->ioprio
= ioprio_best(req
->ioprio
, next
->ioprio
);
2894 __blk_put_request(q
, next
);
2898 static inline int attempt_back_merge(struct request_queue
*q
,
2901 struct request
*next
= elv_latter_request(q
, rq
);
2904 return attempt_merge(q
, rq
, next
);
2909 static inline int attempt_front_merge(struct request_queue
*q
,
2912 struct request
*prev
= elv_former_request(q
, rq
);
2915 return attempt_merge(q
, prev
, rq
);
2920 static void init_request_from_bio(struct request
*req
, struct bio
*bio
)
2922 req
->cmd_type
= REQ_TYPE_FS
;
2925 * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
2927 if (bio_rw_ahead(bio
) || bio_failfast(bio
))
2928 req
->cmd_flags
|= REQ_FAILFAST
;
2931 * REQ_BARRIER implies no merging, but lets make it explicit
2933 if (unlikely(bio_barrier(bio
)))
2934 req
->cmd_flags
|= (REQ_HARDBARRIER
| REQ_NOMERGE
);
2937 req
->cmd_flags
|= REQ_RW_SYNC
;
2938 if (bio_rw_meta(bio
))
2939 req
->cmd_flags
|= REQ_RW_META
;
2942 req
->hard_sector
= req
->sector
= bio
->bi_sector
;
2943 req
->hard_nr_sectors
= req
->nr_sectors
= bio_sectors(bio
);
2944 req
->current_nr_sectors
= req
->hard_cur_sectors
= bio_cur_sectors(bio
);
2945 req
->nr_phys_segments
= bio_phys_segments(req
->q
, bio
);
2946 req
->nr_hw_segments
= bio_hw_segments(req
->q
, bio
);
2947 req
->buffer
= bio_data(bio
); /* see ->buffer comment above */
2948 req
->bio
= req
->biotail
= bio
;
2949 req
->ioprio
= bio_prio(bio
);
2950 req
->rq_disk
= bio
->bi_bdev
->bd_disk
;
2951 req
->start_time
= jiffies
;
2954 static int __make_request(struct request_queue
*q
, struct bio
*bio
)
2956 struct request
*req
;
2957 int el_ret
, nr_sectors
, barrier
, err
;
2958 const unsigned short prio
= bio_prio(bio
);
2959 const int sync
= bio_sync(bio
);
2962 nr_sectors
= bio_sectors(bio
);
2965 * low level driver can indicate that it wants pages above a
2966 * certain limit bounced to low memory (ie for highmem, or even
2967 * ISA dma in theory)
2969 blk_queue_bounce(q
, &bio
);
2971 barrier
= bio_barrier(bio
);
2972 if (unlikely(barrier
) && (q
->next_ordered
== QUEUE_ORDERED_NONE
)) {
2977 spin_lock_irq(q
->queue_lock
);
2979 if (unlikely(barrier
) || elv_queue_empty(q
))
2982 el_ret
= elv_merge(q
, &req
, bio
);
2984 case ELEVATOR_BACK_MERGE
:
2985 BUG_ON(!rq_mergeable(req
));
2987 if (!ll_back_merge_fn(q
, req
, bio
))
2990 blk_add_trace_bio(q
, bio
, BLK_TA_BACKMERGE
);
2992 req
->biotail
->bi_next
= bio
;
2994 req
->nr_sectors
= req
->hard_nr_sectors
+= nr_sectors
;
2995 req
->ioprio
= ioprio_best(req
->ioprio
, prio
);
2996 drive_stat_acct(req
, nr_sectors
, 0);
2997 if (!attempt_back_merge(q
, req
))
2998 elv_merged_request(q
, req
, el_ret
);
3001 case ELEVATOR_FRONT_MERGE
:
3002 BUG_ON(!rq_mergeable(req
));
3004 if (!ll_front_merge_fn(q
, req
, bio
))
3007 blk_add_trace_bio(q
, bio
, BLK_TA_FRONTMERGE
);
3009 bio
->bi_next
= req
->bio
;
3013 * may not be valid. if the low level driver said
3014 * it didn't need a bounce buffer then it better
3015 * not touch req->buffer either...
3017 req
->buffer
= bio_data(bio
);
3018 req
->current_nr_sectors
= bio_cur_sectors(bio
);
3019 req
->hard_cur_sectors
= req
->current_nr_sectors
;
3020 req
->sector
= req
->hard_sector
= bio
->bi_sector
;
3021 req
->nr_sectors
= req
->hard_nr_sectors
+= nr_sectors
;
3022 req
->ioprio
= ioprio_best(req
->ioprio
, prio
);
3023 drive_stat_acct(req
, nr_sectors
, 0);
3024 if (!attempt_front_merge(q
, req
))
3025 elv_merged_request(q
, req
, el_ret
);
3028 /* ELV_NO_MERGE: elevator says don't/can't merge. */
3035 * This sync check and mask will be re-done in init_request_from_bio(),
3036 * but we need to set it earlier to expose the sync flag to the
3037 * rq allocator and io schedulers.
3039 rw_flags
= bio_data_dir(bio
);
3041 rw_flags
|= REQ_RW_SYNC
;
3044 * Grab a free request. This is might sleep but can not fail.
3045 * Returns with the queue unlocked.
3047 req
= get_request_wait(q
, rw_flags
, bio
);
3050 * After dropping the lock and possibly sleeping here, our request
3051 * may now be mergeable after it had proven unmergeable (above).
3052 * We don't worry about that case for efficiency. It won't happen
3053 * often, and the elevators are able to handle it.
3055 init_request_from_bio(req
, bio
);
3057 spin_lock_irq(q
->queue_lock
);
3058 if (elv_queue_empty(q
))
3060 add_request(q
, req
);
3063 __generic_unplug_device(q
);
3065 spin_unlock_irq(q
->queue_lock
);
3069 bio_endio(bio
, nr_sectors
<< 9, err
);
3074 * If bio->bi_dev is a partition, remap the location
3076 static inline void blk_partition_remap(struct bio
*bio
)
3078 struct block_device
*bdev
= bio
->bi_bdev
;
3080 if (bdev
!= bdev
->bd_contains
) {
3081 struct hd_struct
*p
= bdev
->bd_part
;
3082 const int rw
= bio_data_dir(bio
);
3084 p
->sectors
[rw
] += bio_sectors(bio
);
3087 bio
->bi_sector
+= p
->start_sect
;
3088 bio
->bi_bdev
= bdev
->bd_contains
;
3090 blk_add_trace_remap(bdev_get_queue(bio
->bi_bdev
), bio
,
3091 bdev
->bd_dev
, bio
->bi_sector
,
3092 bio
->bi_sector
- p
->start_sect
);
3096 static void handle_bad_sector(struct bio
*bio
)
3098 char b
[BDEVNAME_SIZE
];
3100 printk(KERN_INFO
"attempt to access beyond end of device\n");
3101 printk(KERN_INFO
"%s: rw=%ld, want=%Lu, limit=%Lu\n",
3102 bdevname(bio
->bi_bdev
, b
),
3104 (unsigned long long)bio
->bi_sector
+ bio_sectors(bio
),
3105 (long long)(bio
->bi_bdev
->bd_inode
->i_size
>> 9));
3107 set_bit(BIO_EOF
, &bio
->bi_flags
);
3110 #ifdef CONFIG_FAIL_MAKE_REQUEST
3112 static DECLARE_FAULT_ATTR(fail_make_request
);
3114 static int __init
setup_fail_make_request(char *str
)
3116 return setup_fault_attr(&fail_make_request
, str
);
3118 __setup("fail_make_request=", setup_fail_make_request
);
3120 static int should_fail_request(struct bio
*bio
)
3122 if ((bio
->bi_bdev
->bd_disk
->flags
& GENHD_FL_FAIL
) ||
3123 (bio
->bi_bdev
->bd_part
&& bio
->bi_bdev
->bd_part
->make_it_fail
))
3124 return should_fail(&fail_make_request
, bio
->bi_size
);
3129 static int __init
fail_make_request_debugfs(void)
3131 return init_fault_attr_dentries(&fail_make_request
,
3132 "fail_make_request");
3135 late_initcall(fail_make_request_debugfs
);
3137 #else /* CONFIG_FAIL_MAKE_REQUEST */
3139 static inline int should_fail_request(struct bio
*bio
)
3144 #endif /* CONFIG_FAIL_MAKE_REQUEST */
3147 * generic_make_request: hand a buffer to its device driver for I/O
3148 * @bio: The bio describing the location in memory and on the device.
3150 * generic_make_request() is used to make I/O requests of block
3151 * devices. It is passed a &struct bio, which describes the I/O that needs
3154 * generic_make_request() does not return any status. The
3155 * success/failure status of the request, along with notification of
3156 * completion, is delivered asynchronously through the bio->bi_end_io
3157 * function described (one day) else where.
3159 * The caller of generic_make_request must make sure that bi_io_vec
3160 * are set to describe the memory buffer, and that bi_dev and bi_sector are
3161 * set to describe the device address, and the
3162 * bi_end_io and optionally bi_private are set to describe how
3163 * completion notification should be signaled.
3165 * generic_make_request and the drivers it calls may use bi_next if this
3166 * bio happens to be merged with someone else, and may change bi_dev and
3167 * bi_sector for remaps as it sees fit. So the values of these fields
3168 * should NOT be depended on after the call to generic_make_request.
3170 static inline void __generic_make_request(struct bio
*bio
)
3172 struct request_queue
*q
;
3174 sector_t old_sector
;
3175 int ret
, nr_sectors
= bio_sectors(bio
);
3179 /* Test device or partition size, when known. */
3180 maxsector
= bio
->bi_bdev
->bd_inode
->i_size
>> 9;
3182 sector_t sector
= bio
->bi_sector
;
3184 if (maxsector
< nr_sectors
|| maxsector
- nr_sectors
< sector
) {
3186 * This may well happen - the kernel calls bread()
3187 * without checking the size of the device, e.g., when
3188 * mounting a device.
3190 handle_bad_sector(bio
);
3196 * Resolve the mapping until finished. (drivers are
3197 * still free to implement/resolve their own stacking
3198 * by explicitly returning 0)
3200 * NOTE: we don't repeat the blk_size check for each new device.
3201 * Stacking drivers are expected to know what they are doing.
3206 char b
[BDEVNAME_SIZE
];
3208 q
= bdev_get_queue(bio
->bi_bdev
);
3211 "generic_make_request: Trying to access "
3212 "nonexistent block-device %s (%Lu)\n",
3213 bdevname(bio
->bi_bdev
, b
),
3214 (long long) bio
->bi_sector
);
3216 bio_endio(bio
, bio
->bi_size
, -EIO
);
3220 if (unlikely(bio_sectors(bio
) > q
->max_hw_sectors
)) {
3221 printk("bio too big device %s (%u > %u)\n",
3222 bdevname(bio
->bi_bdev
, b
),
3228 if (unlikely(test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
)))
3231 if (should_fail_request(bio
))
3235 * If this device has partitions, remap block n
3236 * of partition p to block n+start(p) of the disk.
3238 blk_partition_remap(bio
);
3240 if (old_sector
!= -1)
3241 blk_add_trace_remap(q
, bio
, old_dev
, bio
->bi_sector
,
3244 blk_add_trace_bio(q
, bio
, BLK_TA_QUEUE
);
3246 old_sector
= bio
->bi_sector
;
3247 old_dev
= bio
->bi_bdev
->bd_dev
;
3249 maxsector
= bio
->bi_bdev
->bd_inode
->i_size
>> 9;
3251 sector_t sector
= bio
->bi_sector
;
3253 if (maxsector
< nr_sectors
||
3254 maxsector
- nr_sectors
< sector
) {
3256 * This may well happen - partitions are not
3257 * checked to make sure they are within the size
3258 * of the whole device.
3260 handle_bad_sector(bio
);
3265 ret
= q
->make_request_fn(q
, bio
);
3270 * We only want one ->make_request_fn to be active at a time,
3271 * else stack usage with stacked devices could be a problem.
3272 * So use current->bio_{list,tail} to keep a list of requests
3273 * submited by a make_request_fn function.
3274 * current->bio_tail is also used as a flag to say if
3275 * generic_make_request is currently active in this task or not.
3276 * If it is NULL, then no make_request is active. If it is non-NULL,
3277 * then a make_request is active, and new requests should be added
3280 void generic_make_request(struct bio
*bio
)
3282 if (current
->bio_tail
) {
3283 /* make_request is active */
3284 *(current
->bio_tail
) = bio
;
3285 bio
->bi_next
= NULL
;
3286 current
->bio_tail
= &bio
->bi_next
;
3289 /* following loop may be a bit non-obvious, and so deserves some
3291 * Before entering the loop, bio->bi_next is NULL (as all callers
3292 * ensure that) so we have a list with a single bio.
3293 * We pretend that we have just taken it off a longer list, so
3294 * we assign bio_list to the next (which is NULL) and bio_tail
3295 * to &bio_list, thus initialising the bio_list of new bios to be
3296 * added. __generic_make_request may indeed add some more bios
3297 * through a recursive call to generic_make_request. If it
3298 * did, we find a non-NULL value in bio_list and re-enter the loop
3299 * from the top. In this case we really did just take the bio
3300 * of the top of the list (no pretending) and so fixup bio_list and
3301 * bio_tail or bi_next, and call into __generic_make_request again.
3303 * The loop was structured like this to make only one call to
3304 * __generic_make_request (which is important as it is large and
3305 * inlined) and to keep the structure simple.
3307 BUG_ON(bio
->bi_next
);
3309 current
->bio_list
= bio
->bi_next
;
3310 if (bio
->bi_next
== NULL
)
3311 current
->bio_tail
= ¤t
->bio_list
;
3313 bio
->bi_next
= NULL
;
3314 __generic_make_request(bio
);
3315 bio
= current
->bio_list
;
3317 current
->bio_tail
= NULL
; /* deactivate */
3320 EXPORT_SYMBOL(generic_make_request
);
3323 * submit_bio: submit a bio to the block device layer for I/O
3324 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
3325 * @bio: The &struct bio which describes the I/O
3327 * submit_bio() is very similar in purpose to generic_make_request(), and
3328 * uses that function to do most of the work. Both are fairly rough
3329 * interfaces, @bio must be presetup and ready for I/O.
3332 void submit_bio(int rw
, struct bio
*bio
)
3334 int count
= bio_sectors(bio
);
3336 BIO_BUG_ON(!bio
->bi_size
);
3337 BIO_BUG_ON(!bio
->bi_io_vec
);
3340 count_vm_events(PGPGOUT
, count
);
3342 task_io_account_read(bio
->bi_size
);
3343 count_vm_events(PGPGIN
, count
);
3346 if (unlikely(block_dump
)) {
3347 char b
[BDEVNAME_SIZE
];
3348 printk(KERN_DEBUG
"%s(%d): %s block %Lu on %s\n",
3349 current
->comm
, current
->pid
,
3350 (rw
& WRITE
) ? "WRITE" : "READ",
3351 (unsigned long long)bio
->bi_sector
,
3352 bdevname(bio
->bi_bdev
,b
));
3355 generic_make_request(bio
);
3358 EXPORT_SYMBOL(submit_bio
);
3360 static void blk_recalc_rq_sectors(struct request
*rq
, int nsect
)
3362 if (blk_fs_request(rq
)) {
3363 rq
->hard_sector
+= nsect
;
3364 rq
->hard_nr_sectors
-= nsect
;
3367 * Move the I/O submission pointers ahead if required.
3369 if ((rq
->nr_sectors
>= rq
->hard_nr_sectors
) &&
3370 (rq
->sector
<= rq
->hard_sector
)) {
3371 rq
->sector
= rq
->hard_sector
;
3372 rq
->nr_sectors
= rq
->hard_nr_sectors
;
3373 rq
->hard_cur_sectors
= bio_cur_sectors(rq
->bio
);
3374 rq
->current_nr_sectors
= rq
->hard_cur_sectors
;
3375 rq
->buffer
= bio_data(rq
->bio
);
3379 * if total number of sectors is less than the first segment
3380 * size, something has gone terribly wrong
3382 if (rq
->nr_sectors
< rq
->current_nr_sectors
) {
3383 printk("blk: request botched\n");
3384 rq
->nr_sectors
= rq
->current_nr_sectors
;
3389 static int __end_that_request_first(struct request
*req
, int uptodate
,
3392 int total_bytes
, bio_nbytes
, error
, next_idx
= 0;
3395 blk_add_trace_rq(req
->q
, req
, BLK_TA_COMPLETE
);
3398 * extend uptodate bool to allow < 0 value to be direct io error
3401 if (end_io_error(uptodate
))
3402 error
= !uptodate
? -EIO
: uptodate
;
3405 * for a REQ_BLOCK_PC request, we want to carry any eventual
3406 * sense key with us all the way through
3408 if (!blk_pc_request(req
))
3412 if (blk_fs_request(req
) && !(req
->cmd_flags
& REQ_QUIET
))
3413 printk("end_request: I/O error, dev %s, sector %llu\n",
3414 req
->rq_disk
? req
->rq_disk
->disk_name
: "?",
3415 (unsigned long long)req
->sector
);
3418 if (blk_fs_request(req
) && req
->rq_disk
) {
3419 const int rw
= rq_data_dir(req
);
3421 disk_stat_add(req
->rq_disk
, sectors
[rw
], nr_bytes
>> 9);
3424 total_bytes
= bio_nbytes
= 0;
3425 while ((bio
= req
->bio
) != NULL
) {
3428 if (nr_bytes
>= bio
->bi_size
) {
3429 req
->bio
= bio
->bi_next
;
3430 nbytes
= bio
->bi_size
;
3431 if (!ordered_bio_endio(req
, bio
, nbytes
, error
))
3432 bio_endio(bio
, nbytes
, error
);
3436 int idx
= bio
->bi_idx
+ next_idx
;
3438 if (unlikely(bio
->bi_idx
>= bio
->bi_vcnt
)) {
3439 blk_dump_rq_flags(req
, "__end_that");
3440 printk("%s: bio idx %d >= vcnt %d\n",
3442 bio
->bi_idx
, bio
->bi_vcnt
);
3446 nbytes
= bio_iovec_idx(bio
, idx
)->bv_len
;
3447 BIO_BUG_ON(nbytes
> bio
->bi_size
);
3450 * not a complete bvec done
3452 if (unlikely(nbytes
> nr_bytes
)) {
3453 bio_nbytes
+= nr_bytes
;
3454 total_bytes
+= nr_bytes
;
3459 * advance to the next vector
3462 bio_nbytes
+= nbytes
;
3465 total_bytes
+= nbytes
;
3468 if ((bio
= req
->bio
)) {
3470 * end more in this run, or just return 'not-done'
3472 if (unlikely(nr_bytes
<= 0))
3484 * if the request wasn't completed, update state
3487 if (!ordered_bio_endio(req
, bio
, bio_nbytes
, error
))
3488 bio_endio(bio
, bio_nbytes
, error
);
3489 bio
->bi_idx
+= next_idx
;
3490 bio_iovec(bio
)->bv_offset
+= nr_bytes
;
3491 bio_iovec(bio
)->bv_len
-= nr_bytes
;
3494 blk_recalc_rq_sectors(req
, total_bytes
>> 9);
3495 blk_recalc_rq_segments(req
);
3500 * end_that_request_first - end I/O on a request
3501 * @req: the request being processed
3502 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3503 * @nr_sectors: number of sectors to end I/O on
3506 * Ends I/O on a number of sectors attached to @req, and sets it up
3507 * for the next range of segments (if any) in the cluster.
3510 * 0 - we are done with this request, call end_that_request_last()
3511 * 1 - still buffers pending for this request
3513 int end_that_request_first(struct request
*req
, int uptodate
, int nr_sectors
)
3515 return __end_that_request_first(req
, uptodate
, nr_sectors
<< 9);
3518 EXPORT_SYMBOL(end_that_request_first
);
3521 * end_that_request_chunk - end I/O on a request
3522 * @req: the request being processed
3523 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3524 * @nr_bytes: number of bytes to complete
3527 * Ends I/O on a number of bytes attached to @req, and sets it up
3528 * for the next range of segments (if any). Like end_that_request_first(),
3529 * but deals with bytes instead of sectors.
3532 * 0 - we are done with this request, call end_that_request_last()
3533 * 1 - still buffers pending for this request
3535 int end_that_request_chunk(struct request
*req
, int uptodate
, int nr_bytes
)
3537 return __end_that_request_first(req
, uptodate
, nr_bytes
);
3540 EXPORT_SYMBOL(end_that_request_chunk
);
3543 * splice the completion data to a local structure and hand off to
3544 * process_completion_queue() to complete the requests
3546 static void blk_done_softirq(struct softirq_action
*h
)
3548 struct list_head
*cpu_list
, local_list
;
3550 local_irq_disable();
3551 cpu_list
= &__get_cpu_var(blk_cpu_done
);
3552 list_replace_init(cpu_list
, &local_list
);
3555 while (!list_empty(&local_list
)) {
3556 struct request
*rq
= list_entry(local_list
.next
, struct request
, donelist
);
3558 list_del_init(&rq
->donelist
);
3559 rq
->q
->softirq_done_fn(rq
);
3563 static int blk_cpu_notify(struct notifier_block
*self
, unsigned long action
,
3567 * If a CPU goes away, splice its entries to the current CPU
3568 * and trigger a run of the softirq
3570 if (action
== CPU_DEAD
|| action
== CPU_DEAD_FROZEN
) {
3571 int cpu
= (unsigned long) hcpu
;
3573 local_irq_disable();
3574 list_splice_init(&per_cpu(blk_cpu_done
, cpu
),
3575 &__get_cpu_var(blk_cpu_done
));
3576 raise_softirq_irqoff(BLOCK_SOFTIRQ
);
3584 static struct notifier_block __devinitdata blk_cpu_notifier
= {
3585 .notifier_call
= blk_cpu_notify
,
3589 * blk_complete_request - end I/O on a request
3590 * @req: the request being processed
3593 * Ends all I/O on a request. It does not handle partial completions,
3594 * unless the driver actually implements this in its completion callback
3595 * through requeueing. Theh actual completion happens out-of-order,
3596 * through a softirq handler. The user must have registered a completion
3597 * callback through blk_queue_softirq_done().
3600 void blk_complete_request(struct request
*req
)
3602 struct list_head
*cpu_list
;
3603 unsigned long flags
;
3605 BUG_ON(!req
->q
->softirq_done_fn
);
3607 local_irq_save(flags
);
3609 cpu_list
= &__get_cpu_var(blk_cpu_done
);
3610 list_add_tail(&req
->donelist
, cpu_list
);
3611 raise_softirq_irqoff(BLOCK_SOFTIRQ
);
3613 local_irq_restore(flags
);
3616 EXPORT_SYMBOL(blk_complete_request
);
3619 * queue lock must be held
3621 void end_that_request_last(struct request
*req
, int uptodate
)
3623 struct gendisk
*disk
= req
->rq_disk
;
3627 * extend uptodate bool to allow < 0 value to be direct io error
3630 if (end_io_error(uptodate
))
3631 error
= !uptodate
? -EIO
: uptodate
;
3633 if (unlikely(laptop_mode
) && blk_fs_request(req
))
3634 laptop_io_completion();
3637 * Account IO completion. bar_rq isn't accounted as a normal
3638 * IO on queueing nor completion. Accounting the containing
3639 * request is enough.
3641 if (disk
&& blk_fs_request(req
) && req
!= &req
->q
->bar_rq
) {
3642 unsigned long duration
= jiffies
- req
->start_time
;
3643 const int rw
= rq_data_dir(req
);
3645 __disk_stat_inc(disk
, ios
[rw
]);
3646 __disk_stat_add(disk
, ticks
[rw
], duration
);
3647 disk_round_stats(disk
);
3651 req
->end_io(req
, error
);
3653 __blk_put_request(req
->q
, req
);
3656 EXPORT_SYMBOL(end_that_request_last
);
3658 void end_request(struct request
*req
, int uptodate
)
3660 if (!end_that_request_first(req
, uptodate
, req
->hard_cur_sectors
)) {
3661 add_disk_randomness(req
->rq_disk
);
3662 blkdev_dequeue_request(req
);
3663 end_that_request_last(req
, uptodate
);
3667 EXPORT_SYMBOL(end_request
);
3669 void blk_rq_bio_prep(struct request_queue
*q
, struct request
*rq
,
3672 /* first two bits are identical in rq->cmd_flags and bio->bi_rw */
3673 rq
->cmd_flags
|= (bio
->bi_rw
& 3);
3675 rq
->nr_phys_segments
= bio_phys_segments(q
, bio
);
3676 rq
->nr_hw_segments
= bio_hw_segments(q
, bio
);
3677 rq
->current_nr_sectors
= bio_cur_sectors(bio
);
3678 rq
->hard_cur_sectors
= rq
->current_nr_sectors
;
3679 rq
->hard_nr_sectors
= rq
->nr_sectors
= bio_sectors(bio
);
3680 rq
->buffer
= bio_data(bio
);
3681 rq
->data_len
= bio
->bi_size
;
3683 rq
->bio
= rq
->biotail
= bio
;
3686 EXPORT_SYMBOL(blk_rq_bio_prep
);
3688 int kblockd_schedule_work(struct work_struct
*work
)
3690 return queue_work(kblockd_workqueue
, work
);
3693 EXPORT_SYMBOL(kblockd_schedule_work
);
3695 void kblockd_flush_work(struct work_struct
*work
)
3697 cancel_work_sync(work
);
3699 EXPORT_SYMBOL(kblockd_flush_work
);
3701 int __init
blk_dev_init(void)
3705 kblockd_workqueue
= create_workqueue("kblockd");
3706 if (!kblockd_workqueue
)
3707 panic("Failed to create kblockd\n");
3709 request_cachep
= kmem_cache_create("blkdev_requests",
3710 sizeof(struct request
), 0, SLAB_PANIC
, NULL
);
3712 requestq_cachep
= kmem_cache_create("blkdev_queue",
3713 sizeof(struct request_queue
), 0, SLAB_PANIC
, NULL
);
3715 iocontext_cachep
= kmem_cache_create("blkdev_ioc",
3716 sizeof(struct io_context
), 0, SLAB_PANIC
, NULL
);
3718 for_each_possible_cpu(i
)
3719 INIT_LIST_HEAD(&per_cpu(blk_cpu_done
, i
));
3721 open_softirq(BLOCK_SOFTIRQ
, blk_done_softirq
, NULL
);
3722 register_hotcpu_notifier(&blk_cpu_notifier
);
3724 blk_max_low_pfn
= max_low_pfn
- 1;
3725 blk_max_pfn
= max_pfn
- 1;
3731 * IO Context helper functions
3733 void put_io_context(struct io_context
*ioc
)
3738 BUG_ON(atomic_read(&ioc
->refcount
) == 0);
3740 if (atomic_dec_and_test(&ioc
->refcount
)) {
3741 struct cfq_io_context
*cic
;
3744 if (ioc
->aic
&& ioc
->aic
->dtor
)
3745 ioc
->aic
->dtor(ioc
->aic
);
3746 if (ioc
->cic_root
.rb_node
!= NULL
) {
3747 struct rb_node
*n
= rb_first(&ioc
->cic_root
);
3749 cic
= rb_entry(n
, struct cfq_io_context
, rb_node
);
3754 kmem_cache_free(iocontext_cachep
, ioc
);
3757 EXPORT_SYMBOL(put_io_context
);
3759 /* Called by the exitting task */
3760 void exit_io_context(void)
3762 struct io_context
*ioc
;
3763 struct cfq_io_context
*cic
;
3766 ioc
= current
->io_context
;
3767 current
->io_context
= NULL
;
3768 task_unlock(current
);
3771 if (ioc
->aic
&& ioc
->aic
->exit
)
3772 ioc
->aic
->exit(ioc
->aic
);
3773 if (ioc
->cic_root
.rb_node
!= NULL
) {
3774 cic
= rb_entry(rb_first(&ioc
->cic_root
), struct cfq_io_context
, rb_node
);
3778 put_io_context(ioc
);
3782 * If the current task has no IO context then create one and initialise it.
3783 * Otherwise, return its existing IO context.
3785 * This returned IO context doesn't have a specifically elevated refcount,
3786 * but since the current task itself holds a reference, the context can be
3787 * used in general code, so long as it stays within `current` context.
3789 static struct io_context
*current_io_context(gfp_t gfp_flags
, int node
)
3791 struct task_struct
*tsk
= current
;
3792 struct io_context
*ret
;
3794 ret
= tsk
->io_context
;
3798 ret
= kmem_cache_alloc_node(iocontext_cachep
, gfp_flags
, node
);
3800 atomic_set(&ret
->refcount
, 1);
3801 ret
->task
= current
;
3802 ret
->ioprio_changed
= 0;
3803 ret
->last_waited
= jiffies
; /* doesn't matter... */
3804 ret
->nr_batch_requests
= 0; /* because this is 0 */
3806 ret
->cic_root
.rb_node
= NULL
;
3807 ret
->ioc_data
= NULL
;
3808 /* make sure set_task_ioprio() sees the settings above */
3810 tsk
->io_context
= ret
;
3817 * If the current task has no IO context then create one and initialise it.
3818 * If it does have a context, take a ref on it.
3820 * This is always called in the context of the task which submitted the I/O.
3822 struct io_context
*get_io_context(gfp_t gfp_flags
, int node
)
3824 struct io_context
*ret
;
3825 ret
= current_io_context(gfp_flags
, node
);
3827 atomic_inc(&ret
->refcount
);
3830 EXPORT_SYMBOL(get_io_context
);
3832 void copy_io_context(struct io_context
**pdst
, struct io_context
**psrc
)
3834 struct io_context
*src
= *psrc
;
3835 struct io_context
*dst
= *pdst
;
3838 BUG_ON(atomic_read(&src
->refcount
) == 0);
3839 atomic_inc(&src
->refcount
);
3840 put_io_context(dst
);
3844 EXPORT_SYMBOL(copy_io_context
);
3846 void swap_io_context(struct io_context
**ioc1
, struct io_context
**ioc2
)
3848 struct io_context
*temp
;
3853 EXPORT_SYMBOL(swap_io_context
);
3858 struct queue_sysfs_entry
{
3859 struct attribute attr
;
3860 ssize_t (*show
)(struct request_queue
*, char *);
3861 ssize_t (*store
)(struct request_queue
*, const char *, size_t);
3865 queue_var_show(unsigned int var
, char *page
)
3867 return sprintf(page
, "%d\n", var
);
3871 queue_var_store(unsigned long *var
, const char *page
, size_t count
)
3873 char *p
= (char *) page
;
3875 *var
= simple_strtoul(p
, &p
, 10);
3879 static ssize_t
queue_requests_show(struct request_queue
*q
, char *page
)
3881 return queue_var_show(q
->nr_requests
, (page
));
3885 queue_requests_store(struct request_queue
*q
, const char *page
, size_t count
)
3887 struct request_list
*rl
= &q
->rq
;
3889 int ret
= queue_var_store(&nr
, page
, count
);
3890 if (nr
< BLKDEV_MIN_RQ
)
3893 spin_lock_irq(q
->queue_lock
);
3894 q
->nr_requests
= nr
;
3895 blk_queue_congestion_threshold(q
);
3897 if (rl
->count
[READ
] >= queue_congestion_on_threshold(q
))
3898 blk_set_queue_congested(q
, READ
);
3899 else if (rl
->count
[READ
] < queue_congestion_off_threshold(q
))
3900 blk_clear_queue_congested(q
, READ
);
3902 if (rl
->count
[WRITE
] >= queue_congestion_on_threshold(q
))
3903 blk_set_queue_congested(q
, WRITE
);
3904 else if (rl
->count
[WRITE
] < queue_congestion_off_threshold(q
))
3905 blk_clear_queue_congested(q
, WRITE
);
3907 if (rl
->count
[READ
] >= q
->nr_requests
) {
3908 blk_set_queue_full(q
, READ
);
3909 } else if (rl
->count
[READ
]+1 <= q
->nr_requests
) {
3910 blk_clear_queue_full(q
, READ
);
3911 wake_up(&rl
->wait
[READ
]);
3914 if (rl
->count
[WRITE
] >= q
->nr_requests
) {
3915 blk_set_queue_full(q
, WRITE
);
3916 } else if (rl
->count
[WRITE
]+1 <= q
->nr_requests
) {
3917 blk_clear_queue_full(q
, WRITE
);
3918 wake_up(&rl
->wait
[WRITE
]);
3920 spin_unlock_irq(q
->queue_lock
);
3924 static ssize_t
queue_ra_show(struct request_queue
*q
, char *page
)
3926 int ra_kb
= q
->backing_dev_info
.ra_pages
<< (PAGE_CACHE_SHIFT
- 10);
3928 return queue_var_show(ra_kb
, (page
));
3932 queue_ra_store(struct request_queue
*q
, const char *page
, size_t count
)
3934 unsigned long ra_kb
;
3935 ssize_t ret
= queue_var_store(&ra_kb
, page
, count
);
3937 spin_lock_irq(q
->queue_lock
);
3938 q
->backing_dev_info
.ra_pages
= ra_kb
>> (PAGE_CACHE_SHIFT
- 10);
3939 spin_unlock_irq(q
->queue_lock
);
3944 static ssize_t
queue_max_sectors_show(struct request_queue
*q
, char *page
)
3946 int max_sectors_kb
= q
->max_sectors
>> 1;
3948 return queue_var_show(max_sectors_kb
, (page
));
3952 queue_max_sectors_store(struct request_queue
*q
, const char *page
, size_t count
)
3954 unsigned long max_sectors_kb
,
3955 max_hw_sectors_kb
= q
->max_hw_sectors
>> 1,
3956 page_kb
= 1 << (PAGE_CACHE_SHIFT
- 10);
3957 ssize_t ret
= queue_var_store(&max_sectors_kb
, page
, count
);
3960 if (max_sectors_kb
> max_hw_sectors_kb
|| max_sectors_kb
< page_kb
)
3963 * Take the queue lock to update the readahead and max_sectors
3964 * values synchronously:
3966 spin_lock_irq(q
->queue_lock
);
3968 * Trim readahead window as well, if necessary:
3970 ra_kb
= q
->backing_dev_info
.ra_pages
<< (PAGE_CACHE_SHIFT
- 10);
3971 if (ra_kb
> max_sectors_kb
)
3972 q
->backing_dev_info
.ra_pages
=
3973 max_sectors_kb
>> (PAGE_CACHE_SHIFT
- 10);
3975 q
->max_sectors
= max_sectors_kb
<< 1;
3976 spin_unlock_irq(q
->queue_lock
);
3981 static ssize_t
queue_max_hw_sectors_show(struct request_queue
*q
, char *page
)
3983 int max_hw_sectors_kb
= q
->max_hw_sectors
>> 1;
3985 return queue_var_show(max_hw_sectors_kb
, (page
));
3989 static struct queue_sysfs_entry queue_requests_entry
= {
3990 .attr
= {.name
= "nr_requests", .mode
= S_IRUGO
| S_IWUSR
},
3991 .show
= queue_requests_show
,
3992 .store
= queue_requests_store
,
3995 static struct queue_sysfs_entry queue_ra_entry
= {
3996 .attr
= {.name
= "read_ahead_kb", .mode
= S_IRUGO
| S_IWUSR
},
3997 .show
= queue_ra_show
,
3998 .store
= queue_ra_store
,
4001 static struct queue_sysfs_entry queue_max_sectors_entry
= {
4002 .attr
= {.name
= "max_sectors_kb", .mode
= S_IRUGO
| S_IWUSR
},
4003 .show
= queue_max_sectors_show
,
4004 .store
= queue_max_sectors_store
,
4007 static struct queue_sysfs_entry queue_max_hw_sectors_entry
= {
4008 .attr
= {.name
= "max_hw_sectors_kb", .mode
= S_IRUGO
},
4009 .show
= queue_max_hw_sectors_show
,
4012 static struct queue_sysfs_entry queue_iosched_entry
= {
4013 .attr
= {.name
= "scheduler", .mode
= S_IRUGO
| S_IWUSR
},
4014 .show
= elv_iosched_show
,
4015 .store
= elv_iosched_store
,
4018 static struct attribute
*default_attrs
[] = {
4019 &queue_requests_entry
.attr
,
4020 &queue_ra_entry
.attr
,
4021 &queue_max_hw_sectors_entry
.attr
,
4022 &queue_max_sectors_entry
.attr
,
4023 &queue_iosched_entry
.attr
,
4027 #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
4030 queue_attr_show(struct kobject
*kobj
, struct attribute
*attr
, char *page
)
4032 struct queue_sysfs_entry
*entry
= to_queue(attr
);
4033 struct request_queue
*q
=
4034 container_of(kobj
, struct request_queue
, kobj
);
4039 mutex_lock(&q
->sysfs_lock
);
4040 if (test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
)) {
4041 mutex_unlock(&q
->sysfs_lock
);
4044 res
= entry
->show(q
, page
);
4045 mutex_unlock(&q
->sysfs_lock
);
4050 queue_attr_store(struct kobject
*kobj
, struct attribute
*attr
,
4051 const char *page
, size_t length
)
4053 struct queue_sysfs_entry
*entry
= to_queue(attr
);
4054 struct request_queue
*q
= container_of(kobj
, struct request_queue
, kobj
);
4060 mutex_lock(&q
->sysfs_lock
);
4061 if (test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
)) {
4062 mutex_unlock(&q
->sysfs_lock
);
4065 res
= entry
->store(q
, page
, length
);
4066 mutex_unlock(&q
->sysfs_lock
);
4070 static struct sysfs_ops queue_sysfs_ops
= {
4071 .show
= queue_attr_show
,
4072 .store
= queue_attr_store
,
4075 static struct kobj_type queue_ktype
= {
4076 .sysfs_ops
= &queue_sysfs_ops
,
4077 .default_attrs
= default_attrs
,
4078 .release
= blk_release_queue
,
4081 int blk_register_queue(struct gendisk
*disk
)
4085 struct request_queue
*q
= disk
->queue
;
4087 if (!q
|| !q
->request_fn
)
4090 q
->kobj
.parent
= kobject_get(&disk
->kobj
);
4092 ret
= kobject_add(&q
->kobj
);
4096 kobject_uevent(&q
->kobj
, KOBJ_ADD
);
4098 ret
= elv_register_queue(q
);
4100 kobject_uevent(&q
->kobj
, KOBJ_REMOVE
);
4101 kobject_del(&q
->kobj
);
4108 void blk_unregister_queue(struct gendisk
*disk
)
4110 struct request_queue
*q
= disk
->queue
;
4112 if (q
&& q
->request_fn
) {
4113 elv_unregister_queue(q
);
4115 kobject_uevent(&q
->kobj
, KOBJ_REMOVE
);
4116 kobject_del(&q
->kobj
);
4117 kobject_put(&disk
->kobj
);