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
;
1247 struct req_iterator iter
;
1248 int high
, highprv
= 1;
1249 struct request_queue
*q
= rq
->q
;
1254 cluster
= q
->queue_flags
& (1 << QUEUE_FLAG_CLUSTER
);
1255 hw_seg_size
= seg_size
= 0;
1256 phys_size
= hw_size
= nr_phys_segs
= nr_hw_segs
= 0;
1257 rq_for_each_segment(bv
, rq
, iter
) {
1259 * the trick here is making sure that a high page is never
1260 * considered part of another segment, since that might
1261 * change with the bounce page.
1263 high
= page_to_pfn(bv
->bv_page
) > q
->bounce_pfn
;
1264 if (high
|| highprv
)
1265 goto new_hw_segment
;
1267 if (seg_size
+ bv
->bv_len
> q
->max_segment_size
)
1269 if (!BIOVEC_PHYS_MERGEABLE(bvprv
, bv
))
1271 if (!BIOVEC_SEG_BOUNDARY(q
, bvprv
, bv
))
1273 if (BIOVEC_VIRT_OVERSIZE(hw_seg_size
+ bv
->bv_len
))
1274 goto new_hw_segment
;
1276 seg_size
+= bv
->bv_len
;
1277 hw_seg_size
+= bv
->bv_len
;
1282 if (BIOVEC_VIRT_MERGEABLE(bvprv
, bv
) &&
1283 !BIOVEC_VIRT_OVERSIZE(hw_seg_size
+ bv
->bv_len
))
1284 hw_seg_size
+= bv
->bv_len
;
1287 if (nr_hw_segs
== 1 &&
1288 hw_seg_size
> rq
->bio
->bi_hw_front_size
)
1289 rq
->bio
->bi_hw_front_size
= hw_seg_size
;
1290 hw_seg_size
= BIOVEC_VIRT_START_SIZE(bv
) + bv
->bv_len
;
1296 seg_size
= bv
->bv_len
;
1300 if (nr_hw_segs
== 1 &&
1301 hw_seg_size
> rq
->bio
->bi_hw_front_size
)
1302 rq
->bio
->bi_hw_front_size
= hw_seg_size
;
1303 if (hw_seg_size
> rq
->biotail
->bi_hw_back_size
)
1304 rq
->biotail
->bi_hw_back_size
= hw_seg_size
;
1305 rq
->nr_phys_segments
= nr_phys_segs
;
1306 rq
->nr_hw_segments
= nr_hw_segs
;
1309 static int blk_phys_contig_segment(struct request_queue
*q
, struct bio
*bio
,
1312 if (!(q
->queue_flags
& (1 << QUEUE_FLAG_CLUSTER
)))
1315 if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio
), __BVEC_START(nxt
)))
1317 if (bio
->bi_size
+ nxt
->bi_size
> q
->max_segment_size
)
1321 * bio and nxt are contigous in memory, check if the queue allows
1322 * these two to be merged into one
1324 if (BIO_SEG_BOUNDARY(q
, bio
, nxt
))
1330 static int blk_hw_contig_segment(struct request_queue
*q
, struct bio
*bio
,
1333 if (unlikely(!bio_flagged(bio
, BIO_SEG_VALID
)))
1334 blk_recount_segments(q
, bio
);
1335 if (unlikely(!bio_flagged(nxt
, BIO_SEG_VALID
)))
1336 blk_recount_segments(q
, nxt
);
1337 if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio
), __BVEC_START(nxt
)) ||
1338 BIOVEC_VIRT_OVERSIZE(bio
->bi_hw_back_size
+ nxt
->bi_hw_front_size
))
1340 if (bio
->bi_hw_back_size
+ nxt
->bi_hw_front_size
> q
->max_segment_size
)
1347 * map a request to scatterlist, return number of sg entries setup. Caller
1348 * must make sure sg can hold rq->nr_phys_segments entries
1350 int blk_rq_map_sg(struct request_queue
*q
, struct request
*rq
,
1351 struct scatterlist
*sg
)
1353 struct bio_vec
*bvec
, *bvprv
;
1354 struct req_iterator iter
;
1358 cluster
= q
->queue_flags
& (1 << QUEUE_FLAG_CLUSTER
);
1361 * for each bio in rq
1364 rq_for_each_segment(bvec
, rq
, iter
) {
1365 int nbytes
= bvec
->bv_len
;
1367 if (bvprv
&& cluster
) {
1368 if (sg
[nsegs
- 1].length
+ nbytes
> q
->max_segment_size
)
1371 if (!BIOVEC_PHYS_MERGEABLE(bvprv
, bvec
))
1373 if (!BIOVEC_SEG_BOUNDARY(q
, bvprv
, bvec
))
1376 sg
[nsegs
- 1].length
+= nbytes
;
1379 memset(&sg
[nsegs
],0,sizeof(struct scatterlist
));
1380 sg
[nsegs
].page
= bvec
->bv_page
;
1381 sg
[nsegs
].length
= nbytes
;
1382 sg
[nsegs
].offset
= bvec
->bv_offset
;
1387 } /* segments in rq */
1392 EXPORT_SYMBOL(blk_rq_map_sg
);
1395 * the standard queue merge functions, can be overridden with device
1396 * specific ones if so desired
1399 static inline int ll_new_mergeable(struct request_queue
*q
,
1400 struct request
*req
,
1403 int nr_phys_segs
= bio_phys_segments(q
, bio
);
1405 if (req
->nr_phys_segments
+ nr_phys_segs
> q
->max_phys_segments
) {
1406 req
->cmd_flags
|= REQ_NOMERGE
;
1407 if (req
== q
->last_merge
)
1408 q
->last_merge
= NULL
;
1413 * A hw segment is just getting larger, bump just the phys
1416 req
->nr_phys_segments
+= nr_phys_segs
;
1420 static inline int ll_new_hw_segment(struct request_queue
*q
,
1421 struct request
*req
,
1424 int nr_hw_segs
= bio_hw_segments(q
, bio
);
1425 int nr_phys_segs
= bio_phys_segments(q
, bio
);
1427 if (req
->nr_hw_segments
+ nr_hw_segs
> q
->max_hw_segments
1428 || req
->nr_phys_segments
+ nr_phys_segs
> q
->max_phys_segments
) {
1429 req
->cmd_flags
|= REQ_NOMERGE
;
1430 if (req
== q
->last_merge
)
1431 q
->last_merge
= NULL
;
1436 * This will form the start of a new hw segment. Bump both
1439 req
->nr_hw_segments
+= nr_hw_segs
;
1440 req
->nr_phys_segments
+= nr_phys_segs
;
1444 static int ll_back_merge_fn(struct request_queue
*q
, struct request
*req
,
1447 unsigned short max_sectors
;
1450 if (unlikely(blk_pc_request(req
)))
1451 max_sectors
= q
->max_hw_sectors
;
1453 max_sectors
= q
->max_sectors
;
1455 if (req
->nr_sectors
+ bio_sectors(bio
) > max_sectors
) {
1456 req
->cmd_flags
|= REQ_NOMERGE
;
1457 if (req
== q
->last_merge
)
1458 q
->last_merge
= NULL
;
1461 if (unlikely(!bio_flagged(req
->biotail
, BIO_SEG_VALID
)))
1462 blk_recount_segments(q
, req
->biotail
);
1463 if (unlikely(!bio_flagged(bio
, BIO_SEG_VALID
)))
1464 blk_recount_segments(q
, bio
);
1465 len
= req
->biotail
->bi_hw_back_size
+ bio
->bi_hw_front_size
;
1466 if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req
->biotail
), __BVEC_START(bio
)) &&
1467 !BIOVEC_VIRT_OVERSIZE(len
)) {
1468 int mergeable
= ll_new_mergeable(q
, req
, bio
);
1471 if (req
->nr_hw_segments
== 1)
1472 req
->bio
->bi_hw_front_size
= len
;
1473 if (bio
->bi_hw_segments
== 1)
1474 bio
->bi_hw_back_size
= len
;
1479 return ll_new_hw_segment(q
, req
, bio
);
1482 static int ll_front_merge_fn(struct request_queue
*q
, struct request
*req
,
1485 unsigned short max_sectors
;
1488 if (unlikely(blk_pc_request(req
)))
1489 max_sectors
= q
->max_hw_sectors
;
1491 max_sectors
= q
->max_sectors
;
1494 if (req
->nr_sectors
+ bio_sectors(bio
) > max_sectors
) {
1495 req
->cmd_flags
|= REQ_NOMERGE
;
1496 if (req
== q
->last_merge
)
1497 q
->last_merge
= NULL
;
1500 len
= bio
->bi_hw_back_size
+ req
->bio
->bi_hw_front_size
;
1501 if (unlikely(!bio_flagged(bio
, BIO_SEG_VALID
)))
1502 blk_recount_segments(q
, bio
);
1503 if (unlikely(!bio_flagged(req
->bio
, BIO_SEG_VALID
)))
1504 blk_recount_segments(q
, req
->bio
);
1505 if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio
), __BVEC_START(req
->bio
)) &&
1506 !BIOVEC_VIRT_OVERSIZE(len
)) {
1507 int mergeable
= ll_new_mergeable(q
, req
, bio
);
1510 if (bio
->bi_hw_segments
== 1)
1511 bio
->bi_hw_front_size
= len
;
1512 if (req
->nr_hw_segments
== 1)
1513 req
->biotail
->bi_hw_back_size
= len
;
1518 return ll_new_hw_segment(q
, req
, bio
);
1521 static int ll_merge_requests_fn(struct request_queue
*q
, struct request
*req
,
1522 struct request
*next
)
1524 int total_phys_segments
;
1525 int total_hw_segments
;
1528 * First check if the either of the requests are re-queued
1529 * requests. Can't merge them if they are.
1531 if (req
->special
|| next
->special
)
1535 * Will it become too large?
1537 if ((req
->nr_sectors
+ next
->nr_sectors
) > q
->max_sectors
)
1540 total_phys_segments
= req
->nr_phys_segments
+ next
->nr_phys_segments
;
1541 if (blk_phys_contig_segment(q
, req
->biotail
, next
->bio
))
1542 total_phys_segments
--;
1544 if (total_phys_segments
> q
->max_phys_segments
)
1547 total_hw_segments
= req
->nr_hw_segments
+ next
->nr_hw_segments
;
1548 if (blk_hw_contig_segment(q
, req
->biotail
, next
->bio
)) {
1549 int len
= req
->biotail
->bi_hw_back_size
+ next
->bio
->bi_hw_front_size
;
1551 * propagate the combined length to the end of the requests
1553 if (req
->nr_hw_segments
== 1)
1554 req
->bio
->bi_hw_front_size
= len
;
1555 if (next
->nr_hw_segments
== 1)
1556 next
->biotail
->bi_hw_back_size
= len
;
1557 total_hw_segments
--;
1560 if (total_hw_segments
> q
->max_hw_segments
)
1563 /* Merge is OK... */
1564 req
->nr_phys_segments
= total_phys_segments
;
1565 req
->nr_hw_segments
= total_hw_segments
;
1570 * "plug" the device if there are no outstanding requests: this will
1571 * force the transfer to start only after we have put all the requests
1574 * This is called with interrupts off and no requests on the queue and
1575 * with the queue lock held.
1577 void blk_plug_device(struct request_queue
*q
)
1579 WARN_ON(!irqs_disabled());
1582 * don't plug a stopped queue, it must be paired with blk_start_queue()
1583 * which will restart the queueing
1585 if (blk_queue_stopped(q
))
1588 if (!test_and_set_bit(QUEUE_FLAG_PLUGGED
, &q
->queue_flags
)) {
1589 mod_timer(&q
->unplug_timer
, jiffies
+ q
->unplug_delay
);
1590 blk_add_trace_generic(q
, NULL
, 0, BLK_TA_PLUG
);
1594 EXPORT_SYMBOL(blk_plug_device
);
1597 * remove the queue from the plugged list, if present. called with
1598 * queue lock held and interrupts disabled.
1600 int blk_remove_plug(struct request_queue
*q
)
1602 WARN_ON(!irqs_disabled());
1604 if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED
, &q
->queue_flags
))
1607 del_timer(&q
->unplug_timer
);
1611 EXPORT_SYMBOL(blk_remove_plug
);
1614 * remove the plug and let it rip..
1616 void __generic_unplug_device(struct request_queue
*q
)
1618 if (unlikely(blk_queue_stopped(q
)))
1621 if (!blk_remove_plug(q
))
1626 EXPORT_SYMBOL(__generic_unplug_device
);
1629 * generic_unplug_device - fire a request queue
1630 * @q: The &struct request_queue in question
1633 * Linux uses plugging to build bigger requests queues before letting
1634 * the device have at them. If a queue is plugged, the I/O scheduler
1635 * is still adding and merging requests on the queue. Once the queue
1636 * gets unplugged, the request_fn defined for the queue is invoked and
1637 * transfers started.
1639 void generic_unplug_device(struct request_queue
*q
)
1641 spin_lock_irq(q
->queue_lock
);
1642 __generic_unplug_device(q
);
1643 spin_unlock_irq(q
->queue_lock
);
1645 EXPORT_SYMBOL(generic_unplug_device
);
1647 static void blk_backing_dev_unplug(struct backing_dev_info
*bdi
,
1650 struct request_queue
*q
= bdi
->unplug_io_data
;
1653 * devices don't necessarily have an ->unplug_fn defined
1656 blk_add_trace_pdu_int(q
, BLK_TA_UNPLUG_IO
, NULL
,
1657 q
->rq
.count
[READ
] + q
->rq
.count
[WRITE
]);
1663 static void blk_unplug_work(struct work_struct
*work
)
1665 struct request_queue
*q
=
1666 container_of(work
, struct request_queue
, unplug_work
);
1668 blk_add_trace_pdu_int(q
, BLK_TA_UNPLUG_IO
, NULL
,
1669 q
->rq
.count
[READ
] + q
->rq
.count
[WRITE
]);
1674 static void blk_unplug_timeout(unsigned long data
)
1676 struct request_queue
*q
= (struct request_queue
*)data
;
1678 blk_add_trace_pdu_int(q
, BLK_TA_UNPLUG_TIMER
, NULL
,
1679 q
->rq
.count
[READ
] + q
->rq
.count
[WRITE
]);
1681 kblockd_schedule_work(&q
->unplug_work
);
1685 * blk_start_queue - restart a previously stopped queue
1686 * @q: The &struct request_queue in question
1689 * blk_start_queue() will clear the stop flag on the queue, and call
1690 * the request_fn for the queue if it was in a stopped state when
1691 * entered. Also see blk_stop_queue(). Queue lock must be held.
1693 void blk_start_queue(struct request_queue
*q
)
1695 WARN_ON(!irqs_disabled());
1697 clear_bit(QUEUE_FLAG_STOPPED
, &q
->queue_flags
);
1700 * one level of recursion is ok and is much faster than kicking
1701 * the unplug handling
1703 if (!test_and_set_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
)) {
1705 clear_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
);
1708 kblockd_schedule_work(&q
->unplug_work
);
1712 EXPORT_SYMBOL(blk_start_queue
);
1715 * blk_stop_queue - stop a queue
1716 * @q: The &struct request_queue in question
1719 * The Linux block layer assumes that a block driver will consume all
1720 * entries on the request queue when the request_fn strategy is called.
1721 * Often this will not happen, because of hardware limitations (queue
1722 * depth settings). If a device driver gets a 'queue full' response,
1723 * or if it simply chooses not to queue more I/O at one point, it can
1724 * call this function to prevent the request_fn from being called until
1725 * the driver has signalled it's ready to go again. This happens by calling
1726 * blk_start_queue() to restart queue operations. Queue lock must be held.
1728 void blk_stop_queue(struct request_queue
*q
)
1731 set_bit(QUEUE_FLAG_STOPPED
, &q
->queue_flags
);
1733 EXPORT_SYMBOL(blk_stop_queue
);
1736 * blk_sync_queue - cancel any pending callbacks on a queue
1740 * The block layer may perform asynchronous callback activity
1741 * on a queue, such as calling the unplug function after a timeout.
1742 * A block device may call blk_sync_queue to ensure that any
1743 * such activity is cancelled, thus allowing it to release resources
1744 * that the callbacks might use. The caller must already have made sure
1745 * that its ->make_request_fn will not re-add plugging prior to calling
1749 void blk_sync_queue(struct request_queue
*q
)
1751 del_timer_sync(&q
->unplug_timer
);
1753 EXPORT_SYMBOL(blk_sync_queue
);
1756 * blk_run_queue - run a single device queue
1757 * @q: The queue to run
1759 void blk_run_queue(struct request_queue
*q
)
1761 unsigned long flags
;
1763 spin_lock_irqsave(q
->queue_lock
, flags
);
1767 * Only recurse once to avoid overrunning the stack, let the unplug
1768 * handling reinvoke the handler shortly if we already got there.
1770 if (!elv_queue_empty(q
)) {
1771 if (!test_and_set_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
)) {
1773 clear_bit(QUEUE_FLAG_REENTER
, &q
->queue_flags
);
1776 kblockd_schedule_work(&q
->unplug_work
);
1780 spin_unlock_irqrestore(q
->queue_lock
, flags
);
1782 EXPORT_SYMBOL(blk_run_queue
);
1785 * blk_cleanup_queue: - release a &struct request_queue when it is no longer needed
1786 * @kobj: the kobj belonging of the request queue to be released
1789 * blk_cleanup_queue is the pair to blk_init_queue() or
1790 * blk_queue_make_request(). It should be called when a request queue is
1791 * being released; typically when a block device is being de-registered.
1792 * Currently, its primary task it to free all the &struct request
1793 * structures that were allocated to the queue and the queue itself.
1796 * Hopefully the low level driver will have finished any
1797 * outstanding requests first...
1799 static void blk_release_queue(struct kobject
*kobj
)
1801 struct request_queue
*q
=
1802 container_of(kobj
, struct request_queue
, kobj
);
1803 struct request_list
*rl
= &q
->rq
;
1808 mempool_destroy(rl
->rq_pool
);
1811 __blk_queue_free_tags(q
);
1813 blk_trace_shutdown(q
);
1815 kmem_cache_free(requestq_cachep
, q
);
1818 void blk_put_queue(struct request_queue
*q
)
1820 kobject_put(&q
->kobj
);
1822 EXPORT_SYMBOL(blk_put_queue
);
1824 void blk_cleanup_queue(struct request_queue
* q
)
1826 mutex_lock(&q
->sysfs_lock
);
1827 set_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
);
1828 mutex_unlock(&q
->sysfs_lock
);
1831 elevator_exit(q
->elevator
);
1836 EXPORT_SYMBOL(blk_cleanup_queue
);
1838 static int blk_init_free_list(struct request_queue
*q
)
1840 struct request_list
*rl
= &q
->rq
;
1842 rl
->count
[READ
] = rl
->count
[WRITE
] = 0;
1843 rl
->starved
[READ
] = rl
->starved
[WRITE
] = 0;
1845 init_waitqueue_head(&rl
->wait
[READ
]);
1846 init_waitqueue_head(&rl
->wait
[WRITE
]);
1848 rl
->rq_pool
= mempool_create_node(BLKDEV_MIN_RQ
, mempool_alloc_slab
,
1849 mempool_free_slab
, request_cachep
, q
->node
);
1857 struct request_queue
*blk_alloc_queue(gfp_t gfp_mask
)
1859 return blk_alloc_queue_node(gfp_mask
, -1);
1861 EXPORT_SYMBOL(blk_alloc_queue
);
1863 static struct kobj_type queue_ktype
;
1865 struct request_queue
*blk_alloc_queue_node(gfp_t gfp_mask
, int node_id
)
1867 struct request_queue
*q
;
1869 q
= kmem_cache_alloc_node(requestq_cachep
,
1870 gfp_mask
| __GFP_ZERO
, node_id
);
1874 init_timer(&q
->unplug_timer
);
1876 snprintf(q
->kobj
.name
, KOBJ_NAME_LEN
, "%s", "queue");
1877 q
->kobj
.ktype
= &queue_ktype
;
1878 kobject_init(&q
->kobj
);
1880 q
->backing_dev_info
.unplug_io_fn
= blk_backing_dev_unplug
;
1881 q
->backing_dev_info
.unplug_io_data
= q
;
1883 mutex_init(&q
->sysfs_lock
);
1887 EXPORT_SYMBOL(blk_alloc_queue_node
);
1890 * blk_init_queue - prepare a request queue for use with a block device
1891 * @rfn: The function to be called to process requests that have been
1892 * placed on the queue.
1893 * @lock: Request queue spin lock
1896 * If a block device wishes to use the standard request handling procedures,
1897 * which sorts requests and coalesces adjacent requests, then it must
1898 * call blk_init_queue(). The function @rfn will be called when there
1899 * are requests on the queue that need to be processed. If the device
1900 * supports plugging, then @rfn may not be called immediately when requests
1901 * are available on the queue, but may be called at some time later instead.
1902 * Plugged queues are generally unplugged when a buffer belonging to one
1903 * of the requests on the queue is needed, or due to memory pressure.
1905 * @rfn is not required, or even expected, to remove all requests off the
1906 * queue, but only as many as it can handle at a time. If it does leave
1907 * requests on the queue, it is responsible for arranging that the requests
1908 * get dealt with eventually.
1910 * The queue spin lock must be held while manipulating the requests on the
1911 * request queue; this lock will be taken also from interrupt context, so irq
1912 * disabling is needed for it.
1914 * Function returns a pointer to the initialized request queue, or NULL if
1915 * it didn't succeed.
1918 * blk_init_queue() must be paired with a blk_cleanup_queue() call
1919 * when the block device is deactivated (such as at module unload).
1922 struct request_queue
*blk_init_queue(request_fn_proc
*rfn
, spinlock_t
*lock
)
1924 return blk_init_queue_node(rfn
, lock
, -1);
1926 EXPORT_SYMBOL(blk_init_queue
);
1928 struct request_queue
*
1929 blk_init_queue_node(request_fn_proc
*rfn
, spinlock_t
*lock
, int node_id
)
1931 struct request_queue
*q
= blk_alloc_queue_node(GFP_KERNEL
, node_id
);
1937 if (blk_init_free_list(q
)) {
1938 kmem_cache_free(requestq_cachep
, q
);
1943 * if caller didn't supply a lock, they get per-queue locking with
1947 spin_lock_init(&q
->__queue_lock
);
1948 lock
= &q
->__queue_lock
;
1951 q
->request_fn
= rfn
;
1952 q
->prep_rq_fn
= NULL
;
1953 q
->unplug_fn
= generic_unplug_device
;
1954 q
->queue_flags
= (1 << QUEUE_FLAG_CLUSTER
);
1955 q
->queue_lock
= lock
;
1957 blk_queue_segment_boundary(q
, 0xffffffff);
1959 blk_queue_make_request(q
, __make_request
);
1960 blk_queue_max_segment_size(q
, MAX_SEGMENT_SIZE
);
1962 blk_queue_max_hw_segments(q
, MAX_HW_SEGMENTS
);
1963 blk_queue_max_phys_segments(q
, MAX_PHYS_SEGMENTS
);
1965 q
->sg_reserved_size
= INT_MAX
;
1970 if (!elevator_init(q
, NULL
)) {
1971 blk_queue_congestion_threshold(q
);
1978 EXPORT_SYMBOL(blk_init_queue_node
);
1980 int blk_get_queue(struct request_queue
*q
)
1982 if (likely(!test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
))) {
1983 kobject_get(&q
->kobj
);
1990 EXPORT_SYMBOL(blk_get_queue
);
1992 static inline void blk_free_request(struct request_queue
*q
, struct request
*rq
)
1994 if (rq
->cmd_flags
& REQ_ELVPRIV
)
1995 elv_put_request(q
, rq
);
1996 mempool_free(rq
, q
->rq
.rq_pool
);
1999 static struct request
*
2000 blk_alloc_request(struct request_queue
*q
, int rw
, int priv
, gfp_t gfp_mask
)
2002 struct request
*rq
= mempool_alloc(q
->rq
.rq_pool
, gfp_mask
);
2008 * first three bits are identical in rq->cmd_flags and bio->bi_rw,
2009 * see bio.h and blkdev.h
2011 rq
->cmd_flags
= rw
| REQ_ALLOCED
;
2014 if (unlikely(elv_set_request(q
, rq
, gfp_mask
))) {
2015 mempool_free(rq
, q
->rq
.rq_pool
);
2018 rq
->cmd_flags
|= REQ_ELVPRIV
;
2025 * ioc_batching returns true if the ioc is a valid batching request and
2026 * should be given priority access to a request.
2028 static inline int ioc_batching(struct request_queue
*q
, struct io_context
*ioc
)
2034 * Make sure the process is able to allocate at least 1 request
2035 * even if the batch times out, otherwise we could theoretically
2038 return ioc
->nr_batch_requests
== q
->nr_batching
||
2039 (ioc
->nr_batch_requests
> 0
2040 && time_before(jiffies
, ioc
->last_waited
+ BLK_BATCH_TIME
));
2044 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
2045 * will cause the process to be a "batcher" on all queues in the system. This
2046 * is the behaviour we want though - once it gets a wakeup it should be given
2049 static void ioc_set_batching(struct request_queue
*q
, struct io_context
*ioc
)
2051 if (!ioc
|| ioc_batching(q
, ioc
))
2054 ioc
->nr_batch_requests
= q
->nr_batching
;
2055 ioc
->last_waited
= jiffies
;
2058 static void __freed_request(struct request_queue
*q
, int rw
)
2060 struct request_list
*rl
= &q
->rq
;
2062 if (rl
->count
[rw
] < queue_congestion_off_threshold(q
))
2063 blk_clear_queue_congested(q
, rw
);
2065 if (rl
->count
[rw
] + 1 <= q
->nr_requests
) {
2066 if (waitqueue_active(&rl
->wait
[rw
]))
2067 wake_up(&rl
->wait
[rw
]);
2069 blk_clear_queue_full(q
, rw
);
2074 * A request has just been released. Account for it, update the full and
2075 * congestion status, wake up any waiters. Called under q->queue_lock.
2077 static void freed_request(struct request_queue
*q
, int rw
, int priv
)
2079 struct request_list
*rl
= &q
->rq
;
2085 __freed_request(q
, rw
);
2087 if (unlikely(rl
->starved
[rw
^ 1]))
2088 __freed_request(q
, rw
^ 1);
2091 #define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist)
2093 * Get a free request, queue_lock must be held.
2094 * Returns NULL on failure, with queue_lock held.
2095 * Returns !NULL on success, with queue_lock *not held*.
2097 static struct request
*get_request(struct request_queue
*q
, int rw_flags
,
2098 struct bio
*bio
, gfp_t gfp_mask
)
2100 struct request
*rq
= NULL
;
2101 struct request_list
*rl
= &q
->rq
;
2102 struct io_context
*ioc
= NULL
;
2103 const int rw
= rw_flags
& 0x01;
2104 int may_queue
, priv
;
2106 may_queue
= elv_may_queue(q
, rw_flags
);
2107 if (may_queue
== ELV_MQUEUE_NO
)
2110 if (rl
->count
[rw
]+1 >= queue_congestion_on_threshold(q
)) {
2111 if (rl
->count
[rw
]+1 >= q
->nr_requests
) {
2112 ioc
= current_io_context(GFP_ATOMIC
, q
->node
);
2114 * The queue will fill after this allocation, so set
2115 * it as full, and mark this process as "batching".
2116 * This process will be allowed to complete a batch of
2117 * requests, others will be blocked.
2119 if (!blk_queue_full(q
, rw
)) {
2120 ioc_set_batching(q
, ioc
);
2121 blk_set_queue_full(q
, rw
);
2123 if (may_queue
!= ELV_MQUEUE_MUST
2124 && !ioc_batching(q
, ioc
)) {
2126 * The queue is full and the allocating
2127 * process is not a "batcher", and not
2128 * exempted by the IO scheduler
2134 blk_set_queue_congested(q
, rw
);
2138 * Only allow batching queuers to allocate up to 50% over the defined
2139 * limit of requests, otherwise we could have thousands of requests
2140 * allocated with any setting of ->nr_requests
2142 if (rl
->count
[rw
] >= (3 * q
->nr_requests
/ 2))
2146 rl
->starved
[rw
] = 0;
2148 priv
= !test_bit(QUEUE_FLAG_ELVSWITCH
, &q
->queue_flags
);
2152 spin_unlock_irq(q
->queue_lock
);
2154 rq
= blk_alloc_request(q
, rw_flags
, priv
, gfp_mask
);
2155 if (unlikely(!rq
)) {
2157 * Allocation failed presumably due to memory. Undo anything
2158 * we might have messed up.
2160 * Allocating task should really be put onto the front of the
2161 * wait queue, but this is pretty rare.
2163 spin_lock_irq(q
->queue_lock
);
2164 freed_request(q
, rw
, priv
);
2167 * in the very unlikely event that allocation failed and no
2168 * requests for this direction was pending, mark us starved
2169 * so that freeing of a request in the other direction will
2170 * notice us. another possible fix would be to split the
2171 * rq mempool into READ and WRITE
2174 if (unlikely(rl
->count
[rw
] == 0))
2175 rl
->starved
[rw
] = 1;
2181 * ioc may be NULL here, and ioc_batching will be false. That's
2182 * OK, if the queue is under the request limit then requests need
2183 * not count toward the nr_batch_requests limit. There will always
2184 * be some limit enforced by BLK_BATCH_TIME.
2186 if (ioc_batching(q
, ioc
))
2187 ioc
->nr_batch_requests
--;
2191 blk_add_trace_generic(q
, bio
, rw
, BLK_TA_GETRQ
);
2197 * No available requests for this queue, unplug the device and wait for some
2198 * requests to become available.
2200 * Called with q->queue_lock held, and returns with it unlocked.
2202 static struct request
*get_request_wait(struct request_queue
*q
, int rw_flags
,
2205 const int rw
= rw_flags
& 0x01;
2208 rq
= get_request(q
, rw_flags
, bio
, GFP_NOIO
);
2211 struct request_list
*rl
= &q
->rq
;
2213 prepare_to_wait_exclusive(&rl
->wait
[rw
], &wait
,
2214 TASK_UNINTERRUPTIBLE
);
2216 rq
= get_request(q
, rw_flags
, bio
, GFP_NOIO
);
2219 struct io_context
*ioc
;
2221 blk_add_trace_generic(q
, bio
, rw
, BLK_TA_SLEEPRQ
);
2223 __generic_unplug_device(q
);
2224 spin_unlock_irq(q
->queue_lock
);
2228 * After sleeping, we become a "batching" process and
2229 * will be able to allocate at least one request, and
2230 * up to a big batch of them for a small period time.
2231 * See ioc_batching, ioc_set_batching
2233 ioc
= current_io_context(GFP_NOIO
, q
->node
);
2234 ioc_set_batching(q
, ioc
);
2236 spin_lock_irq(q
->queue_lock
);
2238 finish_wait(&rl
->wait
[rw
], &wait
);
2244 struct request
*blk_get_request(struct request_queue
*q
, int rw
, gfp_t gfp_mask
)
2248 BUG_ON(rw
!= READ
&& rw
!= WRITE
);
2250 spin_lock_irq(q
->queue_lock
);
2251 if (gfp_mask
& __GFP_WAIT
) {
2252 rq
= get_request_wait(q
, rw
, NULL
);
2254 rq
= get_request(q
, rw
, NULL
, gfp_mask
);
2256 spin_unlock_irq(q
->queue_lock
);
2258 /* q->queue_lock is unlocked at this point */
2262 EXPORT_SYMBOL(blk_get_request
);
2265 * blk_start_queueing - initiate dispatch of requests to device
2266 * @q: request queue to kick into gear
2268 * This is basically a helper to remove the need to know whether a queue
2269 * is plugged or not if someone just wants to initiate dispatch of requests
2272 * The queue lock must be held with interrupts disabled.
2274 void blk_start_queueing(struct request_queue
*q
)
2276 if (!blk_queue_plugged(q
))
2279 __generic_unplug_device(q
);
2281 EXPORT_SYMBOL(blk_start_queueing
);
2284 * blk_requeue_request - put a request back on queue
2285 * @q: request queue where request should be inserted
2286 * @rq: request to be inserted
2289 * Drivers often keep queueing requests until the hardware cannot accept
2290 * more, when that condition happens we need to put the request back
2291 * on the queue. Must be called with queue lock held.
2293 void blk_requeue_request(struct request_queue
*q
, struct request
*rq
)
2295 blk_add_trace_rq(q
, rq
, BLK_TA_REQUEUE
);
2297 if (blk_rq_tagged(rq
))
2298 blk_queue_end_tag(q
, rq
);
2300 elv_requeue_request(q
, rq
);
2303 EXPORT_SYMBOL(blk_requeue_request
);
2306 * blk_insert_request - insert a special request in to a request queue
2307 * @q: request queue where request should be inserted
2308 * @rq: request to be inserted
2309 * @at_head: insert request at head or tail of queue
2310 * @data: private data
2313 * Many block devices need to execute commands asynchronously, so they don't
2314 * block the whole kernel from preemption during request execution. This is
2315 * accomplished normally by inserting aritficial requests tagged as
2316 * REQ_SPECIAL in to the corresponding request queue, and letting them be
2317 * scheduled for actual execution by the request queue.
2319 * We have the option of inserting the head or the tail of the queue.
2320 * Typically we use the tail for new ioctls and so forth. We use the head
2321 * of the queue for things like a QUEUE_FULL message from a device, or a
2322 * host that is unable to accept a particular command.
2324 void blk_insert_request(struct request_queue
*q
, struct request
*rq
,
2325 int at_head
, void *data
)
2327 int where
= at_head
? ELEVATOR_INSERT_FRONT
: ELEVATOR_INSERT_BACK
;
2328 unsigned long flags
;
2331 * tell I/O scheduler that this isn't a regular read/write (ie it
2332 * must not attempt merges on this) and that it acts as a soft
2335 rq
->cmd_type
= REQ_TYPE_SPECIAL
;
2336 rq
->cmd_flags
|= REQ_SOFTBARRIER
;
2340 spin_lock_irqsave(q
->queue_lock
, flags
);
2343 * If command is tagged, release the tag
2345 if (blk_rq_tagged(rq
))
2346 blk_queue_end_tag(q
, rq
);
2348 drive_stat_acct(rq
, rq
->nr_sectors
, 1);
2349 __elv_add_request(q
, rq
, where
, 0);
2350 blk_start_queueing(q
);
2351 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2354 EXPORT_SYMBOL(blk_insert_request
);
2356 static int __blk_rq_unmap_user(struct bio
*bio
)
2361 if (bio_flagged(bio
, BIO_USER_MAPPED
))
2362 bio_unmap_user(bio
);
2364 ret
= bio_uncopy_user(bio
);
2370 int blk_rq_append_bio(struct request_queue
*q
, struct request
*rq
,
2374 blk_rq_bio_prep(q
, rq
, bio
);
2375 else if (!ll_back_merge_fn(q
, rq
, bio
))
2378 rq
->biotail
->bi_next
= bio
;
2381 rq
->data_len
+= bio
->bi_size
;
2385 EXPORT_SYMBOL(blk_rq_append_bio
);
2387 static int __blk_rq_map_user(struct request_queue
*q
, struct request
*rq
,
2388 void __user
*ubuf
, unsigned int len
)
2390 unsigned long uaddr
;
2391 struct bio
*bio
, *orig_bio
;
2394 reading
= rq_data_dir(rq
) == READ
;
2397 * if alignment requirement is satisfied, map in user pages for
2398 * direct dma. else, set up kernel bounce buffers
2400 uaddr
= (unsigned long) ubuf
;
2401 if (!(uaddr
& queue_dma_alignment(q
)) && !(len
& queue_dma_alignment(q
)))
2402 bio
= bio_map_user(q
, NULL
, uaddr
, len
, reading
);
2404 bio
= bio_copy_user(q
, uaddr
, len
, reading
);
2407 return PTR_ERR(bio
);
2410 blk_queue_bounce(q
, &bio
);
2413 * We link the bounce buffer in and could have to traverse it
2414 * later so we have to get a ref to prevent it from being freed
2418 ret
= blk_rq_append_bio(q
, rq
, bio
);
2420 return bio
->bi_size
;
2422 /* if it was boucned we must call the end io function */
2423 bio_endio(bio
, bio
->bi_size
, 0);
2424 __blk_rq_unmap_user(orig_bio
);
2430 * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
2431 * @q: request queue where request should be inserted
2432 * @rq: request structure to fill
2433 * @ubuf: the user buffer
2434 * @len: length of user data
2437 * Data will be mapped directly for zero copy io, if possible. Otherwise
2438 * a kernel bounce buffer is used.
2440 * A matching blk_rq_unmap_user() must be issued at the end of io, while
2441 * still in process context.
2443 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
2444 * before being submitted to the device, as pages mapped may be out of
2445 * reach. It's the callers responsibility to make sure this happens. The
2446 * original bio must be passed back in to blk_rq_unmap_user() for proper
2449 int blk_rq_map_user(struct request_queue
*q
, struct request
*rq
,
2450 void __user
*ubuf
, unsigned long len
)
2452 unsigned long bytes_read
= 0;
2453 struct bio
*bio
= NULL
;
2456 if (len
> (q
->max_hw_sectors
<< 9))
2461 while (bytes_read
!= len
) {
2462 unsigned long map_len
, end
, start
;
2464 map_len
= min_t(unsigned long, len
- bytes_read
, BIO_MAX_SIZE
);
2465 end
= ((unsigned long)ubuf
+ map_len
+ PAGE_SIZE
- 1)
2467 start
= (unsigned long)ubuf
>> PAGE_SHIFT
;
2470 * A bad offset could cause us to require BIO_MAX_PAGES + 1
2471 * pages. If this happens we just lower the requested
2472 * mapping len by a page so that we can fit
2474 if (end
- start
> BIO_MAX_PAGES
)
2475 map_len
-= PAGE_SIZE
;
2477 ret
= __blk_rq_map_user(q
, rq
, ubuf
, map_len
);
2486 rq
->buffer
= rq
->data
= NULL
;
2489 blk_rq_unmap_user(bio
);
2493 EXPORT_SYMBOL(blk_rq_map_user
);
2496 * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage
2497 * @q: request queue where request should be inserted
2498 * @rq: request to map data to
2499 * @iov: pointer to the iovec
2500 * @iov_count: number of elements in the iovec
2501 * @len: I/O byte count
2504 * Data will be mapped directly for zero copy io, if possible. Otherwise
2505 * a kernel bounce buffer is used.
2507 * A matching blk_rq_unmap_user() must be issued at the end of io, while
2508 * still in process context.
2510 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
2511 * before being submitted to the device, as pages mapped may be out of
2512 * reach. It's the callers responsibility to make sure this happens. The
2513 * original bio must be passed back in to blk_rq_unmap_user() for proper
2516 int blk_rq_map_user_iov(struct request_queue
*q
, struct request
*rq
,
2517 struct sg_iovec
*iov
, int iov_count
, unsigned int len
)
2521 if (!iov
|| iov_count
<= 0)
2524 /* we don't allow misaligned data like bio_map_user() does. If the
2525 * user is using sg, they're expected to know the alignment constraints
2526 * and respect them accordingly */
2527 bio
= bio_map_user_iov(q
, NULL
, iov
, iov_count
, rq_data_dir(rq
)== READ
);
2529 return PTR_ERR(bio
);
2531 if (bio
->bi_size
!= len
) {
2532 bio_endio(bio
, bio
->bi_size
, 0);
2533 bio_unmap_user(bio
);
2538 blk_rq_bio_prep(q
, rq
, bio
);
2539 rq
->buffer
= rq
->data
= NULL
;
2543 EXPORT_SYMBOL(blk_rq_map_user_iov
);
2546 * blk_rq_unmap_user - unmap a request with user data
2547 * @bio: start of bio list
2550 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must
2551 * supply the original rq->bio from the blk_rq_map_user() return, since
2552 * the io completion may have changed rq->bio.
2554 int blk_rq_unmap_user(struct bio
*bio
)
2556 struct bio
*mapped_bio
;
2561 if (unlikely(bio_flagged(bio
, BIO_BOUNCED
)))
2562 mapped_bio
= bio
->bi_private
;
2564 ret2
= __blk_rq_unmap_user(mapped_bio
);
2570 bio_put(mapped_bio
);
2576 EXPORT_SYMBOL(blk_rq_unmap_user
);
2579 * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage
2580 * @q: request queue where request should be inserted
2581 * @rq: request to fill
2582 * @kbuf: the kernel buffer
2583 * @len: length of user data
2584 * @gfp_mask: memory allocation flags
2586 int blk_rq_map_kern(struct request_queue
*q
, struct request
*rq
, void *kbuf
,
2587 unsigned int len
, gfp_t gfp_mask
)
2591 if (len
> (q
->max_hw_sectors
<< 9))
2596 bio
= bio_map_kern(q
, kbuf
, len
, gfp_mask
);
2598 return PTR_ERR(bio
);
2600 if (rq_data_dir(rq
) == WRITE
)
2601 bio
->bi_rw
|= (1 << BIO_RW
);
2603 blk_rq_bio_prep(q
, rq
, bio
);
2604 blk_queue_bounce(q
, &rq
->bio
);
2605 rq
->buffer
= rq
->data
= NULL
;
2609 EXPORT_SYMBOL(blk_rq_map_kern
);
2612 * blk_execute_rq_nowait - insert a request into queue for execution
2613 * @q: queue to insert the request in
2614 * @bd_disk: matching gendisk
2615 * @rq: request to insert
2616 * @at_head: insert request at head or tail of queue
2617 * @done: I/O completion handler
2620 * Insert a fully prepared request at the back of the io scheduler queue
2621 * for execution. Don't wait for completion.
2623 void blk_execute_rq_nowait(struct request_queue
*q
, struct gendisk
*bd_disk
,
2624 struct request
*rq
, int at_head
,
2627 int where
= at_head
? ELEVATOR_INSERT_FRONT
: ELEVATOR_INSERT_BACK
;
2629 rq
->rq_disk
= bd_disk
;
2630 rq
->cmd_flags
|= REQ_NOMERGE
;
2632 WARN_ON(irqs_disabled());
2633 spin_lock_irq(q
->queue_lock
);
2634 __elv_add_request(q
, rq
, where
, 1);
2635 __generic_unplug_device(q
);
2636 spin_unlock_irq(q
->queue_lock
);
2638 EXPORT_SYMBOL_GPL(blk_execute_rq_nowait
);
2641 * blk_execute_rq - insert a request into queue for execution
2642 * @q: queue to insert the request in
2643 * @bd_disk: matching gendisk
2644 * @rq: request to insert
2645 * @at_head: insert request at head or tail of queue
2648 * Insert a fully prepared request at the back of the io scheduler queue
2649 * for execution and wait for completion.
2651 int blk_execute_rq(struct request_queue
*q
, struct gendisk
*bd_disk
,
2652 struct request
*rq
, int at_head
)
2654 DECLARE_COMPLETION_ONSTACK(wait
);
2655 char sense
[SCSI_SENSE_BUFFERSIZE
];
2659 * we need an extra reference to the request, so we can look at
2660 * it after io completion
2665 memset(sense
, 0, sizeof(sense
));
2670 rq
->end_io_data
= &wait
;
2671 blk_execute_rq_nowait(q
, bd_disk
, rq
, at_head
, blk_end_sync_rq
);
2672 wait_for_completion(&wait
);
2680 EXPORT_SYMBOL(blk_execute_rq
);
2683 * blkdev_issue_flush - queue a flush
2684 * @bdev: blockdev to issue flush for
2685 * @error_sector: error sector
2688 * Issue a flush for the block device in question. Caller can supply
2689 * room for storing the error offset in case of a flush error, if they
2690 * wish to. Caller must run wait_for_completion() on its own.
2692 int blkdev_issue_flush(struct block_device
*bdev
, sector_t
*error_sector
)
2694 struct request_queue
*q
;
2696 if (bdev
->bd_disk
== NULL
)
2699 q
= bdev_get_queue(bdev
);
2702 if (!q
->issue_flush_fn
)
2705 return q
->issue_flush_fn(q
, bdev
->bd_disk
, error_sector
);
2708 EXPORT_SYMBOL(blkdev_issue_flush
);
2710 static void drive_stat_acct(struct request
*rq
, int nr_sectors
, int new_io
)
2712 int rw
= rq_data_dir(rq
);
2714 if (!blk_fs_request(rq
) || !rq
->rq_disk
)
2718 __disk_stat_inc(rq
->rq_disk
, merges
[rw
]);
2720 disk_round_stats(rq
->rq_disk
);
2721 rq
->rq_disk
->in_flight
++;
2726 * add-request adds a request to the linked list.
2727 * queue lock is held and interrupts disabled, as we muck with the
2728 * request queue list.
2730 static inline void add_request(struct request_queue
* q
, struct request
* req
)
2732 drive_stat_acct(req
, req
->nr_sectors
, 1);
2735 * elevator indicated where it wants this request to be
2736 * inserted at elevator_merge time
2738 __elv_add_request(q
, req
, ELEVATOR_INSERT_SORT
, 0);
2742 * disk_round_stats() - Round off the performance stats on a struct
2745 * The average IO queue length and utilisation statistics are maintained
2746 * by observing the current state of the queue length and the amount of
2747 * time it has been in this state for.
2749 * Normally, that accounting is done on IO completion, but that can result
2750 * in more than a second's worth of IO being accounted for within any one
2751 * second, leading to >100% utilisation. To deal with that, we call this
2752 * function to do a round-off before returning the results when reading
2753 * /proc/diskstats. This accounts immediately for all queue usage up to
2754 * the current jiffies and restarts the counters again.
2756 void disk_round_stats(struct gendisk
*disk
)
2758 unsigned long now
= jiffies
;
2760 if (now
== disk
->stamp
)
2763 if (disk
->in_flight
) {
2764 __disk_stat_add(disk
, time_in_queue
,
2765 disk
->in_flight
* (now
- disk
->stamp
));
2766 __disk_stat_add(disk
, io_ticks
, (now
- disk
->stamp
));
2771 EXPORT_SYMBOL_GPL(disk_round_stats
);
2774 * queue lock must be held
2776 void __blk_put_request(struct request_queue
*q
, struct request
*req
)
2780 if (unlikely(--req
->ref_count
))
2783 elv_completed_request(q
, req
);
2786 * Request may not have originated from ll_rw_blk. if not,
2787 * it didn't come out of our reserved rq pools
2789 if (req
->cmd_flags
& REQ_ALLOCED
) {
2790 int rw
= rq_data_dir(req
);
2791 int priv
= req
->cmd_flags
& REQ_ELVPRIV
;
2793 BUG_ON(!list_empty(&req
->queuelist
));
2794 BUG_ON(!hlist_unhashed(&req
->hash
));
2796 blk_free_request(q
, req
);
2797 freed_request(q
, rw
, priv
);
2801 EXPORT_SYMBOL_GPL(__blk_put_request
);
2803 void blk_put_request(struct request
*req
)
2805 unsigned long flags
;
2806 struct request_queue
*q
= req
->q
;
2809 * Gee, IDE calls in w/ NULL q. Fix IDE and remove the
2810 * following if (q) test.
2813 spin_lock_irqsave(q
->queue_lock
, flags
);
2814 __blk_put_request(q
, req
);
2815 spin_unlock_irqrestore(q
->queue_lock
, flags
);
2819 EXPORT_SYMBOL(blk_put_request
);
2822 * blk_end_sync_rq - executes a completion event on a request
2823 * @rq: request to complete
2824 * @error: end io status of the request
2826 void blk_end_sync_rq(struct request
*rq
, int error
)
2828 struct completion
*waiting
= rq
->end_io_data
;
2830 rq
->end_io_data
= NULL
;
2831 __blk_put_request(rq
->q
, rq
);
2834 * complete last, if this is a stack request the process (and thus
2835 * the rq pointer) could be invalid right after this complete()
2839 EXPORT_SYMBOL(blk_end_sync_rq
);
2842 * Has to be called with the request spinlock acquired
2844 static int attempt_merge(struct request_queue
*q
, struct request
*req
,
2845 struct request
*next
)
2847 if (!rq_mergeable(req
) || !rq_mergeable(next
))
2853 if (req
->sector
+ req
->nr_sectors
!= next
->sector
)
2856 if (rq_data_dir(req
) != rq_data_dir(next
)
2857 || req
->rq_disk
!= next
->rq_disk
2862 * If we are allowed to merge, then append bio list
2863 * from next to rq and release next. merge_requests_fn
2864 * will have updated segment counts, update sector
2867 if (!ll_merge_requests_fn(q
, req
, next
))
2871 * At this point we have either done a back merge
2872 * or front merge. We need the smaller start_time of
2873 * the merged requests to be the current request
2874 * for accounting purposes.
2876 if (time_after(req
->start_time
, next
->start_time
))
2877 req
->start_time
= next
->start_time
;
2879 req
->biotail
->bi_next
= next
->bio
;
2880 req
->biotail
= next
->biotail
;
2882 req
->nr_sectors
= req
->hard_nr_sectors
+= next
->hard_nr_sectors
;
2884 elv_merge_requests(q
, req
, next
);
2887 disk_round_stats(req
->rq_disk
);
2888 req
->rq_disk
->in_flight
--;
2891 req
->ioprio
= ioprio_best(req
->ioprio
, next
->ioprio
);
2893 __blk_put_request(q
, next
);
2897 static inline int attempt_back_merge(struct request_queue
*q
,
2900 struct request
*next
= elv_latter_request(q
, rq
);
2903 return attempt_merge(q
, rq
, next
);
2908 static inline int attempt_front_merge(struct request_queue
*q
,
2911 struct request
*prev
= elv_former_request(q
, rq
);
2914 return attempt_merge(q
, prev
, rq
);
2919 static void init_request_from_bio(struct request
*req
, struct bio
*bio
)
2921 req
->cmd_type
= REQ_TYPE_FS
;
2924 * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
2926 if (bio_rw_ahead(bio
) || bio_failfast(bio
))
2927 req
->cmd_flags
|= REQ_FAILFAST
;
2930 * REQ_BARRIER implies no merging, but lets make it explicit
2932 if (unlikely(bio_barrier(bio
)))
2933 req
->cmd_flags
|= (REQ_HARDBARRIER
| REQ_NOMERGE
);
2936 req
->cmd_flags
|= REQ_RW_SYNC
;
2937 if (bio_rw_meta(bio
))
2938 req
->cmd_flags
|= REQ_RW_META
;
2941 req
->hard_sector
= req
->sector
= bio
->bi_sector
;
2942 req
->hard_nr_sectors
= req
->nr_sectors
= bio_sectors(bio
);
2943 req
->current_nr_sectors
= req
->hard_cur_sectors
= bio_cur_sectors(bio
);
2944 req
->nr_phys_segments
= bio_phys_segments(req
->q
, bio
);
2945 req
->nr_hw_segments
= bio_hw_segments(req
->q
, bio
);
2946 req
->buffer
= bio_data(bio
); /* see ->buffer comment above */
2947 req
->bio
= req
->biotail
= bio
;
2948 req
->ioprio
= bio_prio(bio
);
2949 req
->rq_disk
= bio
->bi_bdev
->bd_disk
;
2950 req
->start_time
= jiffies
;
2953 static int __make_request(struct request_queue
*q
, struct bio
*bio
)
2955 struct request
*req
;
2956 int el_ret
, nr_sectors
, barrier
, err
;
2957 const unsigned short prio
= bio_prio(bio
);
2958 const int sync
= bio_sync(bio
);
2961 nr_sectors
= bio_sectors(bio
);
2964 * low level driver can indicate that it wants pages above a
2965 * certain limit bounced to low memory (ie for highmem, or even
2966 * ISA dma in theory)
2968 blk_queue_bounce(q
, &bio
);
2970 barrier
= bio_barrier(bio
);
2971 if (unlikely(barrier
) && (q
->next_ordered
== QUEUE_ORDERED_NONE
)) {
2976 spin_lock_irq(q
->queue_lock
);
2978 if (unlikely(barrier
) || elv_queue_empty(q
))
2981 el_ret
= elv_merge(q
, &req
, bio
);
2983 case ELEVATOR_BACK_MERGE
:
2984 BUG_ON(!rq_mergeable(req
));
2986 if (!ll_back_merge_fn(q
, req
, bio
))
2989 blk_add_trace_bio(q
, bio
, BLK_TA_BACKMERGE
);
2991 req
->biotail
->bi_next
= bio
;
2993 req
->nr_sectors
= req
->hard_nr_sectors
+= nr_sectors
;
2994 req
->ioprio
= ioprio_best(req
->ioprio
, prio
);
2995 drive_stat_acct(req
, nr_sectors
, 0);
2996 if (!attempt_back_merge(q
, req
))
2997 elv_merged_request(q
, req
, el_ret
);
3000 case ELEVATOR_FRONT_MERGE
:
3001 BUG_ON(!rq_mergeable(req
));
3003 if (!ll_front_merge_fn(q
, req
, bio
))
3006 blk_add_trace_bio(q
, bio
, BLK_TA_FRONTMERGE
);
3008 bio
->bi_next
= req
->bio
;
3012 * may not be valid. if the low level driver said
3013 * it didn't need a bounce buffer then it better
3014 * not touch req->buffer either...
3016 req
->buffer
= bio_data(bio
);
3017 req
->current_nr_sectors
= bio_cur_sectors(bio
);
3018 req
->hard_cur_sectors
= req
->current_nr_sectors
;
3019 req
->sector
= req
->hard_sector
= bio
->bi_sector
;
3020 req
->nr_sectors
= req
->hard_nr_sectors
+= nr_sectors
;
3021 req
->ioprio
= ioprio_best(req
->ioprio
, prio
);
3022 drive_stat_acct(req
, nr_sectors
, 0);
3023 if (!attempt_front_merge(q
, req
))
3024 elv_merged_request(q
, req
, el_ret
);
3027 /* ELV_NO_MERGE: elevator says don't/can't merge. */
3034 * This sync check and mask will be re-done in init_request_from_bio(),
3035 * but we need to set it earlier to expose the sync flag to the
3036 * rq allocator and io schedulers.
3038 rw_flags
= bio_data_dir(bio
);
3040 rw_flags
|= REQ_RW_SYNC
;
3043 * Grab a free request. This is might sleep but can not fail.
3044 * Returns with the queue unlocked.
3046 req
= get_request_wait(q
, rw_flags
, bio
);
3049 * After dropping the lock and possibly sleeping here, our request
3050 * may now be mergeable after it had proven unmergeable (above).
3051 * We don't worry about that case for efficiency. It won't happen
3052 * often, and the elevators are able to handle it.
3054 init_request_from_bio(req
, bio
);
3056 spin_lock_irq(q
->queue_lock
);
3057 if (elv_queue_empty(q
))
3059 add_request(q
, req
);
3062 __generic_unplug_device(q
);
3064 spin_unlock_irq(q
->queue_lock
);
3068 bio_endio(bio
, nr_sectors
<< 9, err
);
3073 * If bio->bi_dev is a partition, remap the location
3075 static inline void blk_partition_remap(struct bio
*bio
)
3077 struct block_device
*bdev
= bio
->bi_bdev
;
3079 if (bdev
!= bdev
->bd_contains
) {
3080 struct hd_struct
*p
= bdev
->bd_part
;
3081 const int rw
= bio_data_dir(bio
);
3083 p
->sectors
[rw
] += bio_sectors(bio
);
3086 bio
->bi_sector
+= p
->start_sect
;
3087 bio
->bi_bdev
= bdev
->bd_contains
;
3089 blk_add_trace_remap(bdev_get_queue(bio
->bi_bdev
), bio
,
3090 bdev
->bd_dev
, bio
->bi_sector
,
3091 bio
->bi_sector
- p
->start_sect
);
3095 static void handle_bad_sector(struct bio
*bio
)
3097 char b
[BDEVNAME_SIZE
];
3099 printk(KERN_INFO
"attempt to access beyond end of device\n");
3100 printk(KERN_INFO
"%s: rw=%ld, want=%Lu, limit=%Lu\n",
3101 bdevname(bio
->bi_bdev
, b
),
3103 (unsigned long long)bio
->bi_sector
+ bio_sectors(bio
),
3104 (long long)(bio
->bi_bdev
->bd_inode
->i_size
>> 9));
3106 set_bit(BIO_EOF
, &bio
->bi_flags
);
3109 #ifdef CONFIG_FAIL_MAKE_REQUEST
3111 static DECLARE_FAULT_ATTR(fail_make_request
);
3113 static int __init
setup_fail_make_request(char *str
)
3115 return setup_fault_attr(&fail_make_request
, str
);
3117 __setup("fail_make_request=", setup_fail_make_request
);
3119 static int should_fail_request(struct bio
*bio
)
3121 if ((bio
->bi_bdev
->bd_disk
->flags
& GENHD_FL_FAIL
) ||
3122 (bio
->bi_bdev
->bd_part
&& bio
->bi_bdev
->bd_part
->make_it_fail
))
3123 return should_fail(&fail_make_request
, bio
->bi_size
);
3128 static int __init
fail_make_request_debugfs(void)
3130 return init_fault_attr_dentries(&fail_make_request
,
3131 "fail_make_request");
3134 late_initcall(fail_make_request_debugfs
);
3136 #else /* CONFIG_FAIL_MAKE_REQUEST */
3138 static inline int should_fail_request(struct bio
*bio
)
3143 #endif /* CONFIG_FAIL_MAKE_REQUEST */
3146 * generic_make_request: hand a buffer to its device driver for I/O
3147 * @bio: The bio describing the location in memory and on the device.
3149 * generic_make_request() is used to make I/O requests of block
3150 * devices. It is passed a &struct bio, which describes the I/O that needs
3153 * generic_make_request() does not return any status. The
3154 * success/failure status of the request, along with notification of
3155 * completion, is delivered asynchronously through the bio->bi_end_io
3156 * function described (one day) else where.
3158 * The caller of generic_make_request must make sure that bi_io_vec
3159 * are set to describe the memory buffer, and that bi_dev and bi_sector are
3160 * set to describe the device address, and the
3161 * bi_end_io and optionally bi_private are set to describe how
3162 * completion notification should be signaled.
3164 * generic_make_request and the drivers it calls may use bi_next if this
3165 * bio happens to be merged with someone else, and may change bi_dev and
3166 * bi_sector for remaps as it sees fit. So the values of these fields
3167 * should NOT be depended on after the call to generic_make_request.
3169 static inline void __generic_make_request(struct bio
*bio
)
3171 struct request_queue
*q
;
3173 sector_t old_sector
;
3174 int ret
, nr_sectors
= bio_sectors(bio
);
3178 /* Test device or partition size, when known. */
3179 maxsector
= bio
->bi_bdev
->bd_inode
->i_size
>> 9;
3181 sector_t sector
= bio
->bi_sector
;
3183 if (maxsector
< nr_sectors
|| maxsector
- nr_sectors
< sector
) {
3185 * This may well happen - the kernel calls bread()
3186 * without checking the size of the device, e.g., when
3187 * mounting a device.
3189 handle_bad_sector(bio
);
3195 * Resolve the mapping until finished. (drivers are
3196 * still free to implement/resolve their own stacking
3197 * by explicitly returning 0)
3199 * NOTE: we don't repeat the blk_size check for each new device.
3200 * Stacking drivers are expected to know what they are doing.
3205 char b
[BDEVNAME_SIZE
];
3207 q
= bdev_get_queue(bio
->bi_bdev
);
3210 "generic_make_request: Trying to access "
3211 "nonexistent block-device %s (%Lu)\n",
3212 bdevname(bio
->bi_bdev
, b
),
3213 (long long) bio
->bi_sector
);
3215 bio_endio(bio
, bio
->bi_size
, -EIO
);
3219 if (unlikely(bio_sectors(bio
) > q
->max_hw_sectors
)) {
3220 printk("bio too big device %s (%u > %u)\n",
3221 bdevname(bio
->bi_bdev
, b
),
3227 if (unlikely(test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
)))
3230 if (should_fail_request(bio
))
3234 * If this device has partitions, remap block n
3235 * of partition p to block n+start(p) of the disk.
3237 blk_partition_remap(bio
);
3239 if (old_sector
!= -1)
3240 blk_add_trace_remap(q
, bio
, old_dev
, bio
->bi_sector
,
3243 blk_add_trace_bio(q
, bio
, BLK_TA_QUEUE
);
3245 old_sector
= bio
->bi_sector
;
3246 old_dev
= bio
->bi_bdev
->bd_dev
;
3248 maxsector
= bio
->bi_bdev
->bd_inode
->i_size
>> 9;
3250 sector_t sector
= bio
->bi_sector
;
3252 if (maxsector
< nr_sectors
||
3253 maxsector
- nr_sectors
< sector
) {
3255 * This may well happen - partitions are not
3256 * checked to make sure they are within the size
3257 * of the whole device.
3259 handle_bad_sector(bio
);
3264 ret
= q
->make_request_fn(q
, bio
);
3269 * We only want one ->make_request_fn to be active at a time,
3270 * else stack usage with stacked devices could be a problem.
3271 * So use current->bio_{list,tail} to keep a list of requests
3272 * submited by a make_request_fn function.
3273 * current->bio_tail is also used as a flag to say if
3274 * generic_make_request is currently active in this task or not.
3275 * If it is NULL, then no make_request is active. If it is non-NULL,
3276 * then a make_request is active, and new requests should be added
3279 void generic_make_request(struct bio
*bio
)
3281 if (current
->bio_tail
) {
3282 /* make_request is active */
3283 *(current
->bio_tail
) = bio
;
3284 bio
->bi_next
= NULL
;
3285 current
->bio_tail
= &bio
->bi_next
;
3288 /* following loop may be a bit non-obvious, and so deserves some
3290 * Before entering the loop, bio->bi_next is NULL (as all callers
3291 * ensure that) so we have a list with a single bio.
3292 * We pretend that we have just taken it off a longer list, so
3293 * we assign bio_list to the next (which is NULL) and bio_tail
3294 * to &bio_list, thus initialising the bio_list of new bios to be
3295 * added. __generic_make_request may indeed add some more bios
3296 * through a recursive call to generic_make_request. If it
3297 * did, we find a non-NULL value in bio_list and re-enter the loop
3298 * from the top. In this case we really did just take the bio
3299 * of the top of the list (no pretending) and so fixup bio_list and
3300 * bio_tail or bi_next, and call into __generic_make_request again.
3302 * The loop was structured like this to make only one call to
3303 * __generic_make_request (which is important as it is large and
3304 * inlined) and to keep the structure simple.
3306 BUG_ON(bio
->bi_next
);
3308 current
->bio_list
= bio
->bi_next
;
3309 if (bio
->bi_next
== NULL
)
3310 current
->bio_tail
= ¤t
->bio_list
;
3312 bio
->bi_next
= NULL
;
3313 __generic_make_request(bio
);
3314 bio
= current
->bio_list
;
3316 current
->bio_tail
= NULL
; /* deactivate */
3319 EXPORT_SYMBOL(generic_make_request
);
3322 * submit_bio: submit a bio to the block device layer for I/O
3323 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
3324 * @bio: The &struct bio which describes the I/O
3326 * submit_bio() is very similar in purpose to generic_make_request(), and
3327 * uses that function to do most of the work. Both are fairly rough
3328 * interfaces, @bio must be presetup and ready for I/O.
3331 void submit_bio(int rw
, struct bio
*bio
)
3333 int count
= bio_sectors(bio
);
3335 BIO_BUG_ON(!bio
->bi_size
);
3336 BIO_BUG_ON(!bio
->bi_io_vec
);
3339 count_vm_events(PGPGOUT
, count
);
3341 task_io_account_read(bio
->bi_size
);
3342 count_vm_events(PGPGIN
, count
);
3345 if (unlikely(block_dump
)) {
3346 char b
[BDEVNAME_SIZE
];
3347 printk(KERN_DEBUG
"%s(%d): %s block %Lu on %s\n",
3348 current
->comm
, current
->pid
,
3349 (rw
& WRITE
) ? "WRITE" : "READ",
3350 (unsigned long long)bio
->bi_sector
,
3351 bdevname(bio
->bi_bdev
,b
));
3354 generic_make_request(bio
);
3357 EXPORT_SYMBOL(submit_bio
);
3359 static void blk_recalc_rq_sectors(struct request
*rq
, int nsect
)
3361 if (blk_fs_request(rq
)) {
3362 rq
->hard_sector
+= nsect
;
3363 rq
->hard_nr_sectors
-= nsect
;
3366 * Move the I/O submission pointers ahead if required.
3368 if ((rq
->nr_sectors
>= rq
->hard_nr_sectors
) &&
3369 (rq
->sector
<= rq
->hard_sector
)) {
3370 rq
->sector
= rq
->hard_sector
;
3371 rq
->nr_sectors
= rq
->hard_nr_sectors
;
3372 rq
->hard_cur_sectors
= bio_cur_sectors(rq
->bio
);
3373 rq
->current_nr_sectors
= rq
->hard_cur_sectors
;
3374 rq
->buffer
= bio_data(rq
->bio
);
3378 * if total number of sectors is less than the first segment
3379 * size, something has gone terribly wrong
3381 if (rq
->nr_sectors
< rq
->current_nr_sectors
) {
3382 printk("blk: request botched\n");
3383 rq
->nr_sectors
= rq
->current_nr_sectors
;
3388 static int __end_that_request_first(struct request
*req
, int uptodate
,
3391 int total_bytes
, bio_nbytes
, error
, next_idx
= 0;
3394 blk_add_trace_rq(req
->q
, req
, BLK_TA_COMPLETE
);
3397 * extend uptodate bool to allow < 0 value to be direct io error
3400 if (end_io_error(uptodate
))
3401 error
= !uptodate
? -EIO
: uptodate
;
3404 * for a REQ_BLOCK_PC request, we want to carry any eventual
3405 * sense key with us all the way through
3407 if (!blk_pc_request(req
))
3411 if (blk_fs_request(req
) && !(req
->cmd_flags
& REQ_QUIET
))
3412 printk("end_request: I/O error, dev %s, sector %llu\n",
3413 req
->rq_disk
? req
->rq_disk
->disk_name
: "?",
3414 (unsigned long long)req
->sector
);
3417 if (blk_fs_request(req
) && req
->rq_disk
) {
3418 const int rw
= rq_data_dir(req
);
3420 disk_stat_add(req
->rq_disk
, sectors
[rw
], nr_bytes
>> 9);
3423 total_bytes
= bio_nbytes
= 0;
3424 while ((bio
= req
->bio
) != NULL
) {
3427 if (nr_bytes
>= bio
->bi_size
) {
3428 req
->bio
= bio
->bi_next
;
3429 nbytes
= bio
->bi_size
;
3430 if (!ordered_bio_endio(req
, bio
, nbytes
, error
))
3431 bio_endio(bio
, nbytes
, error
);
3435 int idx
= bio
->bi_idx
+ next_idx
;
3437 if (unlikely(bio
->bi_idx
>= bio
->bi_vcnt
)) {
3438 blk_dump_rq_flags(req
, "__end_that");
3439 printk("%s: bio idx %d >= vcnt %d\n",
3441 bio
->bi_idx
, bio
->bi_vcnt
);
3445 nbytes
= bio_iovec_idx(bio
, idx
)->bv_len
;
3446 BIO_BUG_ON(nbytes
> bio
->bi_size
);
3449 * not a complete bvec done
3451 if (unlikely(nbytes
> nr_bytes
)) {
3452 bio_nbytes
+= nr_bytes
;
3453 total_bytes
+= nr_bytes
;
3458 * advance to the next vector
3461 bio_nbytes
+= nbytes
;
3464 total_bytes
+= nbytes
;
3467 if ((bio
= req
->bio
)) {
3469 * end more in this run, or just return 'not-done'
3471 if (unlikely(nr_bytes
<= 0))
3483 * if the request wasn't completed, update state
3486 if (!ordered_bio_endio(req
, bio
, bio_nbytes
, error
))
3487 bio_endio(bio
, bio_nbytes
, error
);
3488 bio
->bi_idx
+= next_idx
;
3489 bio_iovec(bio
)->bv_offset
+= nr_bytes
;
3490 bio_iovec(bio
)->bv_len
-= nr_bytes
;
3493 blk_recalc_rq_sectors(req
, total_bytes
>> 9);
3494 blk_recalc_rq_segments(req
);
3499 * end_that_request_first - end I/O on a request
3500 * @req: the request being processed
3501 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3502 * @nr_sectors: number of sectors to end I/O on
3505 * Ends I/O on a number of sectors attached to @req, and sets it up
3506 * for the next range of segments (if any) in the cluster.
3509 * 0 - we are done with this request, call end_that_request_last()
3510 * 1 - still buffers pending for this request
3512 int end_that_request_first(struct request
*req
, int uptodate
, int nr_sectors
)
3514 return __end_that_request_first(req
, uptodate
, nr_sectors
<< 9);
3517 EXPORT_SYMBOL(end_that_request_first
);
3520 * end_that_request_chunk - end I/O on a request
3521 * @req: the request being processed
3522 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3523 * @nr_bytes: number of bytes to complete
3526 * Ends I/O on a number of bytes attached to @req, and sets it up
3527 * for the next range of segments (if any). Like end_that_request_first(),
3528 * but deals with bytes instead of sectors.
3531 * 0 - we are done with this request, call end_that_request_last()
3532 * 1 - still buffers pending for this request
3534 int end_that_request_chunk(struct request
*req
, int uptodate
, int nr_bytes
)
3536 return __end_that_request_first(req
, uptodate
, nr_bytes
);
3539 EXPORT_SYMBOL(end_that_request_chunk
);
3542 * splice the completion data to a local structure and hand off to
3543 * process_completion_queue() to complete the requests
3545 static void blk_done_softirq(struct softirq_action
*h
)
3547 struct list_head
*cpu_list
, local_list
;
3549 local_irq_disable();
3550 cpu_list
= &__get_cpu_var(blk_cpu_done
);
3551 list_replace_init(cpu_list
, &local_list
);
3554 while (!list_empty(&local_list
)) {
3555 struct request
*rq
= list_entry(local_list
.next
, struct request
, donelist
);
3557 list_del_init(&rq
->donelist
);
3558 rq
->q
->softirq_done_fn(rq
);
3562 static int blk_cpu_notify(struct notifier_block
*self
, unsigned long action
,
3566 * If a CPU goes away, splice its entries to the current CPU
3567 * and trigger a run of the softirq
3569 if (action
== CPU_DEAD
|| action
== CPU_DEAD_FROZEN
) {
3570 int cpu
= (unsigned long) hcpu
;
3572 local_irq_disable();
3573 list_splice_init(&per_cpu(blk_cpu_done
, cpu
),
3574 &__get_cpu_var(blk_cpu_done
));
3575 raise_softirq_irqoff(BLOCK_SOFTIRQ
);
3583 static struct notifier_block __devinitdata blk_cpu_notifier
= {
3584 .notifier_call
= blk_cpu_notify
,
3588 * blk_complete_request - end I/O on a request
3589 * @req: the request being processed
3592 * Ends all I/O on a request. It does not handle partial completions,
3593 * unless the driver actually implements this in its completion callback
3594 * through requeueing. Theh actual completion happens out-of-order,
3595 * through a softirq handler. The user must have registered a completion
3596 * callback through blk_queue_softirq_done().
3599 void blk_complete_request(struct request
*req
)
3601 struct list_head
*cpu_list
;
3602 unsigned long flags
;
3604 BUG_ON(!req
->q
->softirq_done_fn
);
3606 local_irq_save(flags
);
3608 cpu_list
= &__get_cpu_var(blk_cpu_done
);
3609 list_add_tail(&req
->donelist
, cpu_list
);
3610 raise_softirq_irqoff(BLOCK_SOFTIRQ
);
3612 local_irq_restore(flags
);
3615 EXPORT_SYMBOL(blk_complete_request
);
3618 * queue lock must be held
3620 void end_that_request_last(struct request
*req
, int uptodate
)
3622 struct gendisk
*disk
= req
->rq_disk
;
3626 * extend uptodate bool to allow < 0 value to be direct io error
3629 if (end_io_error(uptodate
))
3630 error
= !uptodate
? -EIO
: uptodate
;
3632 if (unlikely(laptop_mode
) && blk_fs_request(req
))
3633 laptop_io_completion();
3636 * Account IO completion. bar_rq isn't accounted as a normal
3637 * IO on queueing nor completion. Accounting the containing
3638 * request is enough.
3640 if (disk
&& blk_fs_request(req
) && req
!= &req
->q
->bar_rq
) {
3641 unsigned long duration
= jiffies
- req
->start_time
;
3642 const int rw
= rq_data_dir(req
);
3644 __disk_stat_inc(disk
, ios
[rw
]);
3645 __disk_stat_add(disk
, ticks
[rw
], duration
);
3646 disk_round_stats(disk
);
3650 req
->end_io(req
, error
);
3652 __blk_put_request(req
->q
, req
);
3655 EXPORT_SYMBOL(end_that_request_last
);
3657 void end_request(struct request
*req
, int uptodate
)
3659 if (!end_that_request_first(req
, uptodate
, req
->hard_cur_sectors
)) {
3660 add_disk_randomness(req
->rq_disk
);
3661 blkdev_dequeue_request(req
);
3662 end_that_request_last(req
, uptodate
);
3666 EXPORT_SYMBOL(end_request
);
3668 void blk_rq_bio_prep(struct request_queue
*q
, struct request
*rq
,
3671 /* first two bits are identical in rq->cmd_flags and bio->bi_rw */
3672 rq
->cmd_flags
|= (bio
->bi_rw
& 3);
3674 rq
->nr_phys_segments
= bio_phys_segments(q
, bio
);
3675 rq
->nr_hw_segments
= bio_hw_segments(q
, bio
);
3676 rq
->current_nr_sectors
= bio_cur_sectors(bio
);
3677 rq
->hard_cur_sectors
= rq
->current_nr_sectors
;
3678 rq
->hard_nr_sectors
= rq
->nr_sectors
= bio_sectors(bio
);
3679 rq
->buffer
= bio_data(bio
);
3680 rq
->data_len
= bio
->bi_size
;
3682 rq
->bio
= rq
->biotail
= bio
;
3685 EXPORT_SYMBOL(blk_rq_bio_prep
);
3687 int kblockd_schedule_work(struct work_struct
*work
)
3689 return queue_work(kblockd_workqueue
, work
);
3692 EXPORT_SYMBOL(kblockd_schedule_work
);
3694 void kblockd_flush_work(struct work_struct
*work
)
3696 cancel_work_sync(work
);
3698 EXPORT_SYMBOL(kblockd_flush_work
);
3700 int __init
blk_dev_init(void)
3704 kblockd_workqueue
= create_workqueue("kblockd");
3705 if (!kblockd_workqueue
)
3706 panic("Failed to create kblockd\n");
3708 request_cachep
= kmem_cache_create("blkdev_requests",
3709 sizeof(struct request
), 0, SLAB_PANIC
, NULL
);
3711 requestq_cachep
= kmem_cache_create("blkdev_queue",
3712 sizeof(struct request_queue
), 0, SLAB_PANIC
, NULL
);
3714 iocontext_cachep
= kmem_cache_create("blkdev_ioc",
3715 sizeof(struct io_context
), 0, SLAB_PANIC
, NULL
);
3717 for_each_possible_cpu(i
)
3718 INIT_LIST_HEAD(&per_cpu(blk_cpu_done
, i
));
3720 open_softirq(BLOCK_SOFTIRQ
, blk_done_softirq
, NULL
);
3721 register_hotcpu_notifier(&blk_cpu_notifier
);
3723 blk_max_low_pfn
= max_low_pfn
- 1;
3724 blk_max_pfn
= max_pfn
- 1;
3730 * IO Context helper functions
3732 void put_io_context(struct io_context
*ioc
)
3737 BUG_ON(atomic_read(&ioc
->refcount
) == 0);
3739 if (atomic_dec_and_test(&ioc
->refcount
)) {
3740 struct cfq_io_context
*cic
;
3743 if (ioc
->aic
&& ioc
->aic
->dtor
)
3744 ioc
->aic
->dtor(ioc
->aic
);
3745 if (ioc
->cic_root
.rb_node
!= NULL
) {
3746 struct rb_node
*n
= rb_first(&ioc
->cic_root
);
3748 cic
= rb_entry(n
, struct cfq_io_context
, rb_node
);
3753 kmem_cache_free(iocontext_cachep
, ioc
);
3756 EXPORT_SYMBOL(put_io_context
);
3758 /* Called by the exitting task */
3759 void exit_io_context(void)
3761 struct io_context
*ioc
;
3762 struct cfq_io_context
*cic
;
3765 ioc
= current
->io_context
;
3766 current
->io_context
= NULL
;
3767 task_unlock(current
);
3770 if (ioc
->aic
&& ioc
->aic
->exit
)
3771 ioc
->aic
->exit(ioc
->aic
);
3772 if (ioc
->cic_root
.rb_node
!= NULL
) {
3773 cic
= rb_entry(rb_first(&ioc
->cic_root
), struct cfq_io_context
, rb_node
);
3777 put_io_context(ioc
);
3781 * If the current task has no IO context then create one and initialise it.
3782 * Otherwise, return its existing IO context.
3784 * This returned IO context doesn't have a specifically elevated refcount,
3785 * but since the current task itself holds a reference, the context can be
3786 * used in general code, so long as it stays within `current` context.
3788 static struct io_context
*current_io_context(gfp_t gfp_flags
, int node
)
3790 struct task_struct
*tsk
= current
;
3791 struct io_context
*ret
;
3793 ret
= tsk
->io_context
;
3797 ret
= kmem_cache_alloc_node(iocontext_cachep
, gfp_flags
, node
);
3799 atomic_set(&ret
->refcount
, 1);
3800 ret
->task
= current
;
3801 ret
->ioprio_changed
= 0;
3802 ret
->last_waited
= jiffies
; /* doesn't matter... */
3803 ret
->nr_batch_requests
= 0; /* because this is 0 */
3805 ret
->cic_root
.rb_node
= NULL
;
3806 ret
->ioc_data
= NULL
;
3807 /* make sure set_task_ioprio() sees the settings above */
3809 tsk
->io_context
= ret
;
3816 * If the current task has no IO context then create one and initialise it.
3817 * If it does have a context, take a ref on it.
3819 * This is always called in the context of the task which submitted the I/O.
3821 struct io_context
*get_io_context(gfp_t gfp_flags
, int node
)
3823 struct io_context
*ret
;
3824 ret
= current_io_context(gfp_flags
, node
);
3826 atomic_inc(&ret
->refcount
);
3829 EXPORT_SYMBOL(get_io_context
);
3831 void copy_io_context(struct io_context
**pdst
, struct io_context
**psrc
)
3833 struct io_context
*src
= *psrc
;
3834 struct io_context
*dst
= *pdst
;
3837 BUG_ON(atomic_read(&src
->refcount
) == 0);
3838 atomic_inc(&src
->refcount
);
3839 put_io_context(dst
);
3843 EXPORT_SYMBOL(copy_io_context
);
3845 void swap_io_context(struct io_context
**ioc1
, struct io_context
**ioc2
)
3847 struct io_context
*temp
;
3852 EXPORT_SYMBOL(swap_io_context
);
3857 struct queue_sysfs_entry
{
3858 struct attribute attr
;
3859 ssize_t (*show
)(struct request_queue
*, char *);
3860 ssize_t (*store
)(struct request_queue
*, const char *, size_t);
3864 queue_var_show(unsigned int var
, char *page
)
3866 return sprintf(page
, "%d\n", var
);
3870 queue_var_store(unsigned long *var
, const char *page
, size_t count
)
3872 char *p
= (char *) page
;
3874 *var
= simple_strtoul(p
, &p
, 10);
3878 static ssize_t
queue_requests_show(struct request_queue
*q
, char *page
)
3880 return queue_var_show(q
->nr_requests
, (page
));
3884 queue_requests_store(struct request_queue
*q
, const char *page
, size_t count
)
3886 struct request_list
*rl
= &q
->rq
;
3888 int ret
= queue_var_store(&nr
, page
, count
);
3889 if (nr
< BLKDEV_MIN_RQ
)
3892 spin_lock_irq(q
->queue_lock
);
3893 q
->nr_requests
= nr
;
3894 blk_queue_congestion_threshold(q
);
3896 if (rl
->count
[READ
] >= queue_congestion_on_threshold(q
))
3897 blk_set_queue_congested(q
, READ
);
3898 else if (rl
->count
[READ
] < queue_congestion_off_threshold(q
))
3899 blk_clear_queue_congested(q
, READ
);
3901 if (rl
->count
[WRITE
] >= queue_congestion_on_threshold(q
))
3902 blk_set_queue_congested(q
, WRITE
);
3903 else if (rl
->count
[WRITE
] < queue_congestion_off_threshold(q
))
3904 blk_clear_queue_congested(q
, WRITE
);
3906 if (rl
->count
[READ
] >= q
->nr_requests
) {
3907 blk_set_queue_full(q
, READ
);
3908 } else if (rl
->count
[READ
]+1 <= q
->nr_requests
) {
3909 blk_clear_queue_full(q
, READ
);
3910 wake_up(&rl
->wait
[READ
]);
3913 if (rl
->count
[WRITE
] >= q
->nr_requests
) {
3914 blk_set_queue_full(q
, WRITE
);
3915 } else if (rl
->count
[WRITE
]+1 <= q
->nr_requests
) {
3916 blk_clear_queue_full(q
, WRITE
);
3917 wake_up(&rl
->wait
[WRITE
]);
3919 spin_unlock_irq(q
->queue_lock
);
3923 static ssize_t
queue_ra_show(struct request_queue
*q
, char *page
)
3925 int ra_kb
= q
->backing_dev_info
.ra_pages
<< (PAGE_CACHE_SHIFT
- 10);
3927 return queue_var_show(ra_kb
, (page
));
3931 queue_ra_store(struct request_queue
*q
, const char *page
, size_t count
)
3933 unsigned long ra_kb
;
3934 ssize_t ret
= queue_var_store(&ra_kb
, page
, count
);
3936 spin_lock_irq(q
->queue_lock
);
3937 q
->backing_dev_info
.ra_pages
= ra_kb
>> (PAGE_CACHE_SHIFT
- 10);
3938 spin_unlock_irq(q
->queue_lock
);
3943 static ssize_t
queue_max_sectors_show(struct request_queue
*q
, char *page
)
3945 int max_sectors_kb
= q
->max_sectors
>> 1;
3947 return queue_var_show(max_sectors_kb
, (page
));
3951 queue_max_sectors_store(struct request_queue
*q
, const char *page
, size_t count
)
3953 unsigned long max_sectors_kb
,
3954 max_hw_sectors_kb
= q
->max_hw_sectors
>> 1,
3955 page_kb
= 1 << (PAGE_CACHE_SHIFT
- 10);
3956 ssize_t ret
= queue_var_store(&max_sectors_kb
, page
, count
);
3959 if (max_sectors_kb
> max_hw_sectors_kb
|| max_sectors_kb
< page_kb
)
3962 * Take the queue lock to update the readahead and max_sectors
3963 * values synchronously:
3965 spin_lock_irq(q
->queue_lock
);
3967 * Trim readahead window as well, if necessary:
3969 ra_kb
= q
->backing_dev_info
.ra_pages
<< (PAGE_CACHE_SHIFT
- 10);
3970 if (ra_kb
> max_sectors_kb
)
3971 q
->backing_dev_info
.ra_pages
=
3972 max_sectors_kb
>> (PAGE_CACHE_SHIFT
- 10);
3974 q
->max_sectors
= max_sectors_kb
<< 1;
3975 spin_unlock_irq(q
->queue_lock
);
3980 static ssize_t
queue_max_hw_sectors_show(struct request_queue
*q
, char *page
)
3982 int max_hw_sectors_kb
= q
->max_hw_sectors
>> 1;
3984 return queue_var_show(max_hw_sectors_kb
, (page
));
3988 static struct queue_sysfs_entry queue_requests_entry
= {
3989 .attr
= {.name
= "nr_requests", .mode
= S_IRUGO
| S_IWUSR
},
3990 .show
= queue_requests_show
,
3991 .store
= queue_requests_store
,
3994 static struct queue_sysfs_entry queue_ra_entry
= {
3995 .attr
= {.name
= "read_ahead_kb", .mode
= S_IRUGO
| S_IWUSR
},
3996 .show
= queue_ra_show
,
3997 .store
= queue_ra_store
,
4000 static struct queue_sysfs_entry queue_max_sectors_entry
= {
4001 .attr
= {.name
= "max_sectors_kb", .mode
= S_IRUGO
| S_IWUSR
},
4002 .show
= queue_max_sectors_show
,
4003 .store
= queue_max_sectors_store
,
4006 static struct queue_sysfs_entry queue_max_hw_sectors_entry
= {
4007 .attr
= {.name
= "max_hw_sectors_kb", .mode
= S_IRUGO
},
4008 .show
= queue_max_hw_sectors_show
,
4011 static struct queue_sysfs_entry queue_iosched_entry
= {
4012 .attr
= {.name
= "scheduler", .mode
= S_IRUGO
| S_IWUSR
},
4013 .show
= elv_iosched_show
,
4014 .store
= elv_iosched_store
,
4017 static struct attribute
*default_attrs
[] = {
4018 &queue_requests_entry
.attr
,
4019 &queue_ra_entry
.attr
,
4020 &queue_max_hw_sectors_entry
.attr
,
4021 &queue_max_sectors_entry
.attr
,
4022 &queue_iosched_entry
.attr
,
4026 #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
4029 queue_attr_show(struct kobject
*kobj
, struct attribute
*attr
, char *page
)
4031 struct queue_sysfs_entry
*entry
= to_queue(attr
);
4032 struct request_queue
*q
=
4033 container_of(kobj
, struct request_queue
, kobj
);
4038 mutex_lock(&q
->sysfs_lock
);
4039 if (test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
)) {
4040 mutex_unlock(&q
->sysfs_lock
);
4043 res
= entry
->show(q
, page
);
4044 mutex_unlock(&q
->sysfs_lock
);
4049 queue_attr_store(struct kobject
*kobj
, struct attribute
*attr
,
4050 const char *page
, size_t length
)
4052 struct queue_sysfs_entry
*entry
= to_queue(attr
);
4053 struct request_queue
*q
= container_of(kobj
, struct request_queue
, kobj
);
4059 mutex_lock(&q
->sysfs_lock
);
4060 if (test_bit(QUEUE_FLAG_DEAD
, &q
->queue_flags
)) {
4061 mutex_unlock(&q
->sysfs_lock
);
4064 res
= entry
->store(q
, page
, length
);
4065 mutex_unlock(&q
->sysfs_lock
);
4069 static struct sysfs_ops queue_sysfs_ops
= {
4070 .show
= queue_attr_show
,
4071 .store
= queue_attr_store
,
4074 static struct kobj_type queue_ktype
= {
4075 .sysfs_ops
= &queue_sysfs_ops
,
4076 .default_attrs
= default_attrs
,
4077 .release
= blk_release_queue
,
4080 int blk_register_queue(struct gendisk
*disk
)
4084 struct request_queue
*q
= disk
->queue
;
4086 if (!q
|| !q
->request_fn
)
4089 q
->kobj
.parent
= kobject_get(&disk
->kobj
);
4091 ret
= kobject_add(&q
->kobj
);
4095 kobject_uevent(&q
->kobj
, KOBJ_ADD
);
4097 ret
= elv_register_queue(q
);
4099 kobject_uevent(&q
->kobj
, KOBJ_REMOVE
);
4100 kobject_del(&q
->kobj
);
4107 void blk_unregister_queue(struct gendisk
*disk
)
4109 struct request_queue
*q
= disk
->queue
;
4111 if (q
&& q
->request_fn
) {
4112 elv_unregister_queue(q
);
4114 kobject_uevent(&q
->kobj
, KOBJ_REMOVE
);
4115 kobject_del(&q
->kobj
);
4116 kobject_put(&disk
->kobj
);