blob: 29bcfac6c68853e4e562642dddadc4c8deb17231 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * 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>
Jens Axboe6728cb02008-01-31 13:03:55 +01006 * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au>
7 * - July2000
Linus Torvalds1da177e2005-04-16 15:20:36 -07008 * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
9 */
10
11/*
12 * This handles all read/write requests to block devices
13 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/backing-dev.h>
17#include <linux/bio.h>
18#include <linux/blkdev.h>
19#include <linux/highmem.h>
20#include <linux/mm.h>
21#include <linux/kernel_stat.h>
22#include <linux/string.h>
23#include <linux/init.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/completion.h>
25#include <linux/slab.h>
26#include <linux/swap.h>
27#include <linux/writeback.h>
Andrew Mortonfaccbd42006-12-10 02:19:35 -080028#include <linux/task_io_accounting_ops.h>
Jens Axboe2056a782006-03-23 20:00:26 +010029#include <linux/blktrace_api.h>
Akinobu Mitac17bb492006-12-08 02:39:46 -080030#include <linux/fault-inject.h>
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +010031#include <trace/block.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070032
Jens Axboe8324aa92008-01-29 14:51:59 +010033#include "blk.h"
34
Ingo Molnar0bfc2452008-11-26 11:59:56 +010035DEFINE_TRACE(block_plug);
36DEFINE_TRACE(block_unplug_io);
37DEFINE_TRACE(block_unplug_timer);
38DEFINE_TRACE(block_getrq);
39DEFINE_TRACE(block_sleeprq);
40DEFINE_TRACE(block_rq_requeue);
41DEFINE_TRACE(block_bio_backmerge);
42DEFINE_TRACE(block_bio_frontmerge);
43DEFINE_TRACE(block_bio_queue);
44DEFINE_TRACE(block_rq_complete);
45DEFINE_TRACE(block_remap); /* Also used in drivers/md/dm.c */
46EXPORT_TRACEPOINT_SYMBOL_GPL(block_remap);
47
Jens Axboe165125e2007-07-24 09:28:11 +020048static int __make_request(struct request_queue *q, struct bio *bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -070049
50/*
51 * For the allocated request tables
52 */
Adrian Bunk5ece6c52008-02-18 13:45:51 +010053static struct kmem_cache *request_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070054
55/*
56 * For queue allocation
57 */
Jens Axboe6728cb02008-01-31 13:03:55 +010058struct kmem_cache *blk_requestq_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070059
60/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070061 * Controlling structure to kblockd
62 */
Jens Axboeff856ba2006-01-09 16:02:34 +010063static struct workqueue_struct *kblockd_workqueue;
Linus Torvalds1da177e2005-04-16 15:20:36 -070064
Jens Axboe26b82562008-01-29 13:54:41 +010065static void drive_stat_acct(struct request *rq, int new_io)
66{
Jens Axboebc58ba92009-01-23 10:54:44 +010067 struct gendisk *disk = rq->rq_disk;
Jens Axboe28f13702008-05-07 10:15:46 +020068 struct hd_struct *part;
Jens Axboe26b82562008-01-29 13:54:41 +010069 int rw = rq_data_dir(rq);
Tejun Heoc9959052008-08-25 19:47:21 +090070 int cpu;
Jens Axboe26b82562008-01-29 13:54:41 +010071
Jens Axboefb8ec182009-02-02 08:42:32 +010072 if (!blk_fs_request(rq) || !disk || !blk_do_io_stat(disk->queue))
Jens Axboe26b82562008-01-29 13:54:41 +010073 return;
74
Tejun Heo074a7ac2008-08-25 19:56:14 +090075 cpu = part_stat_lock();
Tejun Heoe71bf0d2008-09-03 09:03:02 +020076 part = disk_map_sector_rcu(rq->rq_disk, rq->sector);
Tejun Heoc9959052008-08-25 19:47:21 +090077
Jens Axboe28f13702008-05-07 10:15:46 +020078 if (!new_io)
Tejun Heo074a7ac2008-08-25 19:56:14 +090079 part_stat_inc(cpu, part, merges[rw]);
Jens Axboe28f13702008-05-07 10:15:46 +020080 else {
Tejun Heo074a7ac2008-08-25 19:56:14 +090081 part_round_stats(cpu, part);
82 part_inc_in_flight(part);
Jens Axboe26b82562008-01-29 13:54:41 +010083 }
Tejun Heoe71bf0d2008-09-03 09:03:02 +020084
Tejun Heo074a7ac2008-08-25 19:56:14 +090085 part_stat_unlock();
Jens Axboe26b82562008-01-29 13:54:41 +010086}
87
Jens Axboe8324aa92008-01-29 14:51:59 +010088void blk_queue_congestion_threshold(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -070089{
90 int nr;
91
92 nr = q->nr_requests - (q->nr_requests / 8) + 1;
93 if (nr > q->nr_requests)
94 nr = q->nr_requests;
95 q->nr_congestion_on = nr;
96
97 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
98 if (nr < 1)
99 nr = 1;
100 q->nr_congestion_off = nr;
101}
102
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103/**
104 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
105 * @bdev: device
106 *
107 * Locates the passed device's request queue and returns the address of its
108 * backing_dev_info
109 *
110 * Will return NULL if the request queue cannot be located.
111 */
112struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
113{
114 struct backing_dev_info *ret = NULL;
Jens Axboe165125e2007-07-24 09:28:11 +0200115 struct request_queue *q = bdev_get_queue(bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116
117 if (q)
118 ret = &q->backing_dev_info;
119 return ret;
120}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121EXPORT_SYMBOL(blk_get_backing_dev_info);
122
FUJITA Tomonori2a4aa302008-04-29 09:54:36 +0200123void blk_rq_init(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124{
FUJITA Tomonori1afb20f2008-04-25 12:26:28 +0200125 memset(rq, 0, sizeof(*rq));
126
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 INIT_LIST_HEAD(&rq->queuelist);
Jens Axboe242f9dc2008-09-14 05:55:09 -0700128 INIT_LIST_HEAD(&rq->timeout_list);
Jens Axboec7c22e42008-09-13 20:26:01 +0200129 rq->cpu = -1;
Jens Axboe63a71382008-02-08 12:41:03 +0100130 rq->q = q;
131 rq->sector = rq->hard_sector = (sector_t) -1;
Jens Axboe2e662b62006-07-13 11:55:04 +0200132 INIT_HLIST_NODE(&rq->hash);
133 RB_CLEAR_NODE(&rq->rb_node);
FUJITA Tomonorid7e3c322008-04-29 09:54:39 +0200134 rq->cmd = rq->__cmd;
Jens Axboe63a71382008-02-08 12:41:03 +0100135 rq->tag = -1;
Jens Axboe63a71382008-02-08 12:41:03 +0100136 rq->ref_count = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137}
FUJITA Tomonori2a4aa302008-04-29 09:54:36 +0200138EXPORT_SYMBOL(blk_rq_init);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139
NeilBrown5bb23a62007-09-27 12:46:13 +0200140static void req_bio_endio(struct request *rq, struct bio *bio,
141 unsigned int nbytes, int error)
Tejun Heo797e7db2006-01-06 09:51:03 +0100142{
Jens Axboe165125e2007-07-24 09:28:11 +0200143 struct request_queue *q = rq->q;
Tejun Heo797e7db2006-01-06 09:51:03 +0100144
NeilBrown5bb23a62007-09-27 12:46:13 +0200145 if (&q->bar_rq != rq) {
146 if (error)
147 clear_bit(BIO_UPTODATE, &bio->bi_flags);
148 else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
149 error = -EIO;
Tejun Heo797e7db2006-01-06 09:51:03 +0100150
NeilBrown5bb23a62007-09-27 12:46:13 +0200151 if (unlikely(nbytes > bio->bi_size)) {
Jens Axboe6728cb02008-01-31 13:03:55 +0100152 printk(KERN_ERR "%s: want %u bytes done, %u left\n",
Harvey Harrison24c03d42008-05-01 04:35:17 -0700153 __func__, nbytes, bio->bi_size);
NeilBrown5bb23a62007-09-27 12:46:13 +0200154 nbytes = bio->bi_size;
155 }
Tejun Heo797e7db2006-01-06 09:51:03 +0100156
Keith Mannthey08bafc02008-11-25 10:24:35 +0100157 if (unlikely(rq->cmd_flags & REQ_QUIET))
158 set_bit(BIO_QUIET, &bio->bi_flags);
159
NeilBrown5bb23a62007-09-27 12:46:13 +0200160 bio->bi_size -= nbytes;
161 bio->bi_sector += (nbytes >> 9);
Martin K. Petersen7ba1ba12008-06-30 20:04:41 +0200162
163 if (bio_integrity(bio))
164 bio_integrity_advance(bio, nbytes);
165
NeilBrown5bb23a62007-09-27 12:46:13 +0200166 if (bio->bi_size == 0)
NeilBrown6712ecf2007-09-27 12:47:43 +0200167 bio_endio(bio, error);
NeilBrown5bb23a62007-09-27 12:46:13 +0200168 } else {
169
170 /*
171 * Okay, this is the barrier request in progress, just
172 * record the error;
173 */
174 if (error && !q->orderr)
175 q->orderr = error;
176 }
Tejun Heo797e7db2006-01-06 09:51:03 +0100177}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179void blk_dump_rq_flags(struct request *rq, char *msg)
180{
181 int bit;
182
Jens Axboe6728cb02008-01-31 13:03:55 +0100183 printk(KERN_INFO "%s: dev %s: type=%x, flags=%x\n", msg,
Jens Axboe4aff5e22006-08-10 08:44:47 +0200184 rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type,
185 rq->cmd_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186
Jens Axboe6728cb02008-01-31 13:03:55 +0100187 printk(KERN_INFO " sector %llu, nr/cnr %lu/%u\n",
188 (unsigned long long)rq->sector,
189 rq->nr_sectors,
190 rq->current_nr_sectors);
191 printk(KERN_INFO " bio %p, biotail %p, buffer %p, data %p, len %u\n",
192 rq->bio, rq->biotail,
193 rq->buffer, rq->data,
194 rq->data_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195
Jens Axboe4aff5e22006-08-10 08:44:47 +0200196 if (blk_pc_request(rq)) {
Jens Axboe6728cb02008-01-31 13:03:55 +0100197 printk(KERN_INFO " cdb: ");
FUJITA Tomonorid34c87e2008-04-29 14:37:52 +0200198 for (bit = 0; bit < BLK_MAX_CDB; bit++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199 printk("%02x ", rq->cmd[bit]);
200 printk("\n");
201 }
202}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203EXPORT_SYMBOL(blk_dump_rq_flags);
204
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205/*
206 * "plug" the device if there are no outstanding requests: this will
207 * force the transfer to start only after we have put all the requests
208 * on the list.
209 *
210 * This is called with interrupts off and no requests on the queue and
211 * with the queue lock held.
212 */
Jens Axboe165125e2007-07-24 09:28:11 +0200213void blk_plug_device(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214{
215 WARN_ON(!irqs_disabled());
216
217 /*
218 * don't plug a stopped queue, it must be paired with blk_start_queue()
219 * which will restart the queueing
220 */
Coywolf Qi Hunt7daac492006-04-19 10:14:49 +0200221 if (blk_queue_stopped(q))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 return;
223
Jens Axboee48ec692008-07-03 13:18:54 +0200224 if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED, q)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225 mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +0100226 trace_block_plug(q);
Jens Axboe2056a782006-03-23 20:00:26 +0100227 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229EXPORT_SYMBOL(blk_plug_device);
230
Jens Axboe6c5e0c42008-08-01 20:31:32 +0200231/**
232 * blk_plug_device_unlocked - plug a device without queue lock held
233 * @q: The &struct request_queue to plug
234 *
235 * Description:
236 * Like @blk_plug_device(), but grabs the queue lock and disables
237 * interrupts.
238 **/
239void blk_plug_device_unlocked(struct request_queue *q)
240{
241 unsigned long flags;
242
243 spin_lock_irqsave(q->queue_lock, flags);
244 blk_plug_device(q);
245 spin_unlock_irqrestore(q->queue_lock, flags);
246}
247EXPORT_SYMBOL(blk_plug_device_unlocked);
248
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249/*
250 * remove the queue from the plugged list, if present. called with
251 * queue lock held and interrupts disabled.
252 */
Jens Axboe165125e2007-07-24 09:28:11 +0200253int blk_remove_plug(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254{
255 WARN_ON(!irqs_disabled());
256
Jens Axboee48ec692008-07-03 13:18:54 +0200257 if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED, q))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 return 0;
259
260 del_timer(&q->unplug_timer);
261 return 1;
262}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263EXPORT_SYMBOL(blk_remove_plug);
264
265/*
266 * remove the plug and let it rip..
267 */
Jens Axboe165125e2007-07-24 09:28:11 +0200268void __generic_unplug_device(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269{
Coywolf Qi Hunt7daac492006-04-19 10:14:49 +0200270 if (unlikely(blk_queue_stopped(q)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 return;
Jens Axboea31a9732008-10-17 13:58:29 +0200272 if (!blk_remove_plug(q) && !blk_queue_nonrot(q))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 return;
274
Jens Axboe22e2c502005-06-27 10:55:12 +0200275 q->request_fn(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277
278/**
279 * generic_unplug_device - fire a request queue
Jens Axboe165125e2007-07-24 09:28:11 +0200280 * @q: The &struct request_queue in question
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 *
282 * Description:
283 * Linux uses plugging to build bigger requests queues before letting
284 * the device have at them. If a queue is plugged, the I/O scheduler
285 * is still adding and merging requests on the queue. Once the queue
286 * gets unplugged, the request_fn defined for the queue is invoked and
287 * transfers started.
288 **/
Jens Axboe165125e2007-07-24 09:28:11 +0200289void generic_unplug_device(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290{
Jens Axboedbaf2c02008-05-07 09:48:17 +0200291 if (blk_queue_plugged(q)) {
292 spin_lock_irq(q->queue_lock);
293 __generic_unplug_device(q);
294 spin_unlock_irq(q->queue_lock);
295 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296}
297EXPORT_SYMBOL(generic_unplug_device);
298
299static void blk_backing_dev_unplug(struct backing_dev_info *bdi,
300 struct page *page)
301{
Jens Axboe165125e2007-07-24 09:28:11 +0200302 struct request_queue *q = bdi->unplug_io_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303
Alan D. Brunelle2ad8b1e2007-11-07 14:26:56 -0500304 blk_unplug(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305}
306
Jens Axboe86db1e22008-01-29 14:53:40 +0100307void blk_unplug_work(struct work_struct *work)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308{
Jens Axboe165125e2007-07-24 09:28:11 +0200309 struct request_queue *q =
310 container_of(work, struct request_queue, unplug_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +0100312 trace_block_unplug_io(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 q->unplug_fn(q);
314}
315
Jens Axboe86db1e22008-01-29 14:53:40 +0100316void blk_unplug_timeout(unsigned long data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317{
Jens Axboe165125e2007-07-24 09:28:11 +0200318 struct request_queue *q = (struct request_queue *)data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +0100320 trace_block_unplug_timer(q);
Jens Axboe18887ad2008-07-28 13:08:45 +0200321 kblockd_schedule_work(q, &q->unplug_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322}
323
Alan D. Brunelle2ad8b1e2007-11-07 14:26:56 -0500324void blk_unplug(struct request_queue *q)
325{
326 /*
327 * devices don't necessarily have an ->unplug_fn defined
328 */
329 if (q->unplug_fn) {
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +0100330 trace_block_unplug_io(q);
Alan D. Brunelle2ad8b1e2007-11-07 14:26:56 -0500331 q->unplug_fn(q);
332 }
333}
334EXPORT_SYMBOL(blk_unplug);
335
Jens Axboec7c22e42008-09-13 20:26:01 +0200336static void blk_invoke_request_fn(struct request_queue *q)
337{
Jens Axboe80a4b582008-10-14 09:51:06 +0200338 if (unlikely(blk_queue_stopped(q)))
339 return;
340
Jens Axboec7c22e42008-09-13 20:26:01 +0200341 /*
342 * one level of recursion is ok and is much faster than kicking
343 * the unplug handling
344 */
345 if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
346 q->request_fn(q);
347 queue_flag_clear(QUEUE_FLAG_REENTER, q);
348 } else {
349 queue_flag_set(QUEUE_FLAG_PLUGGED, q);
350 kblockd_schedule_work(q, &q->unplug_work);
351 }
352}
353
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354/**
355 * blk_start_queue - restart a previously stopped queue
Jens Axboe165125e2007-07-24 09:28:11 +0200356 * @q: The &struct request_queue in question
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 *
358 * Description:
359 * blk_start_queue() will clear the stop flag on the queue, and call
360 * the request_fn for the queue if it was in a stopped state when
361 * entered. Also see blk_stop_queue(). Queue lock must be held.
362 **/
Jens Axboe165125e2007-07-24 09:28:11 +0200363void blk_start_queue(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364{
Paolo 'Blaisorblade' Giarrussoa038e252006-06-05 12:09:01 +0200365 WARN_ON(!irqs_disabled());
366
Nick Piggin75ad23b2008-04-29 14:48:33 +0200367 queue_flag_clear(QUEUE_FLAG_STOPPED, q);
Jens Axboec7c22e42008-09-13 20:26:01 +0200368 blk_invoke_request_fn(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370EXPORT_SYMBOL(blk_start_queue);
371
372/**
373 * blk_stop_queue - stop a queue
Jens Axboe165125e2007-07-24 09:28:11 +0200374 * @q: The &struct request_queue in question
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 *
376 * Description:
377 * The Linux block layer assumes that a block driver will consume all
378 * entries on the request queue when the request_fn strategy is called.
379 * Often this will not happen, because of hardware limitations (queue
380 * depth settings). If a device driver gets a 'queue full' response,
381 * or if it simply chooses not to queue more I/O at one point, it can
382 * call this function to prevent the request_fn from being called until
383 * the driver has signalled it's ready to go again. This happens by calling
384 * blk_start_queue() to restart queue operations. Queue lock must be held.
385 **/
Jens Axboe165125e2007-07-24 09:28:11 +0200386void blk_stop_queue(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387{
388 blk_remove_plug(q);
Nick Piggin75ad23b2008-04-29 14:48:33 +0200389 queue_flag_set(QUEUE_FLAG_STOPPED, q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390}
391EXPORT_SYMBOL(blk_stop_queue);
392
393/**
394 * blk_sync_queue - cancel any pending callbacks on a queue
395 * @q: the queue
396 *
397 * Description:
398 * The block layer may perform asynchronous callback activity
399 * on a queue, such as calling the unplug function after a timeout.
400 * A block device may call blk_sync_queue to ensure that any
401 * such activity is cancelled, thus allowing it to release resources
Michael Opdenacker59c51592007-05-09 08:57:56 +0200402 * that the callbacks might use. The caller must already have made sure
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 * that its ->make_request_fn will not re-add plugging prior to calling
404 * this function.
405 *
406 */
407void blk_sync_queue(struct request_queue *q)
408{
409 del_timer_sync(&q->unplug_timer);
Jens Axboe70ed28b2008-11-19 14:38:39 +0100410 del_timer_sync(&q->timeout);
Cheng Renquan64d01dc2008-12-03 12:41:39 +0100411 cancel_work_sync(&q->unplug_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412}
413EXPORT_SYMBOL(blk_sync_queue);
414
415/**
Jens Axboe80a4b582008-10-14 09:51:06 +0200416 * __blk_run_queue - run a single device queue
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 * @q: The queue to run
Jens Axboe80a4b582008-10-14 09:51:06 +0200418 *
419 * Description:
420 * See @blk_run_queue. This variant must be called with the queue lock
421 * held and interrupts disabled.
422 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 */
Nick Piggin75ad23b2008-04-29 14:48:33 +0200424void __blk_run_queue(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700425{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 blk_remove_plug(q);
Jens Axboedac07ec2006-05-11 08:20:16 +0200427
428 /*
429 * Only recurse once to avoid overrunning the stack, let the unplug
430 * handling reinvoke the handler shortly if we already got there.
431 */
Jens Axboec7c22e42008-09-13 20:26:01 +0200432 if (!elv_queue_empty(q))
433 blk_invoke_request_fn(q);
Nick Piggin75ad23b2008-04-29 14:48:33 +0200434}
435EXPORT_SYMBOL(__blk_run_queue);
Jens Axboedac07ec2006-05-11 08:20:16 +0200436
Nick Piggin75ad23b2008-04-29 14:48:33 +0200437/**
438 * blk_run_queue - run a single device queue
439 * @q: The queue to run
Jens Axboe80a4b582008-10-14 09:51:06 +0200440 *
441 * Description:
442 * Invoke request handling on this queue, if it has pending work to do.
443 * May be used to restart queueing when a request has completed. Also
444 * See @blk_start_queueing.
445 *
Nick Piggin75ad23b2008-04-29 14:48:33 +0200446 */
447void blk_run_queue(struct request_queue *q)
448{
449 unsigned long flags;
450
451 spin_lock_irqsave(q->queue_lock, flags);
452 __blk_run_queue(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700453 spin_unlock_irqrestore(q->queue_lock, flags);
454}
455EXPORT_SYMBOL(blk_run_queue);
456
Jens Axboe165125e2007-07-24 09:28:11 +0200457void blk_put_queue(struct request_queue *q)
Al Viro483f4af2006-03-18 18:34:37 -0500458{
459 kobject_put(&q->kobj);
460}
Al Viro483f4af2006-03-18 18:34:37 -0500461
Jens Axboe6728cb02008-01-31 13:03:55 +0100462void blk_cleanup_queue(struct request_queue *q)
Al Viro483f4af2006-03-18 18:34:37 -0500463{
Jens Axboee3335de2008-09-18 09:22:54 -0700464 /*
465 * We know we have process context here, so we can be a little
466 * cautious and ensure that pending block actions on this device
467 * are done before moving on. Going into this function, we should
468 * not have processes doing IO to this device.
469 */
470 blk_sync_queue(q);
471
Al Viro483f4af2006-03-18 18:34:37 -0500472 mutex_lock(&q->sysfs_lock);
Nick Piggin75ad23b2008-04-29 14:48:33 +0200473 queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q);
Al Viro483f4af2006-03-18 18:34:37 -0500474 mutex_unlock(&q->sysfs_lock);
475
476 if (q->elevator)
477 elevator_exit(q->elevator);
478
479 blk_put_queue(q);
480}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481EXPORT_SYMBOL(blk_cleanup_queue);
482
Jens Axboe165125e2007-07-24 09:28:11 +0200483static int blk_init_free_list(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484{
485 struct request_list *rl = &q->rq;
486
487 rl->count[READ] = rl->count[WRITE] = 0;
488 rl->starved[READ] = rl->starved[WRITE] = 0;
Tejun Heocb98fc82005-10-28 08:29:39 +0200489 rl->elvpriv = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490 init_waitqueue_head(&rl->wait[READ]);
491 init_waitqueue_head(&rl->wait[WRITE]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492
Christoph Lameter19460892005-06-23 00:08:19 -0700493 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
494 mempool_free_slab, request_cachep, q->node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495
496 if (!rl->rq_pool)
497 return -ENOMEM;
498
499 return 0;
500}
501
Jens Axboe165125e2007-07-24 09:28:11 +0200502struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503{
Christoph Lameter19460892005-06-23 00:08:19 -0700504 return blk_alloc_queue_node(gfp_mask, -1);
505}
506EXPORT_SYMBOL(blk_alloc_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507
Jens Axboe165125e2007-07-24 09:28:11 +0200508struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
Christoph Lameter19460892005-06-23 00:08:19 -0700509{
Jens Axboe165125e2007-07-24 09:28:11 +0200510 struct request_queue *q;
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700511 int err;
Christoph Lameter19460892005-06-23 00:08:19 -0700512
Jens Axboe8324aa92008-01-29 14:51:59 +0100513 q = kmem_cache_alloc_node(blk_requestq_cachep,
Christoph Lameter94f60302007-07-17 04:03:29 -0700514 gfp_mask | __GFP_ZERO, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 if (!q)
516 return NULL;
517
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700518 q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug;
519 q->backing_dev_info.unplug_io_data = q;
520 err = bdi_init(&q->backing_dev_info);
521 if (err) {
Jens Axboe8324aa92008-01-29 14:51:59 +0100522 kmem_cache_free(blk_requestq_cachep, q);
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700523 return NULL;
524 }
525
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 init_timer(&q->unplug_timer);
Jens Axboe242f9dc2008-09-14 05:55:09 -0700527 setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
528 INIT_LIST_HEAD(&q->timeout_list);
Peter Zijlstra713ada92008-10-16 13:44:57 +0200529 INIT_WORK(&q->unplug_work, blk_unplug_work);
Al Viro483f4af2006-03-18 18:34:37 -0500530
Jens Axboe8324aa92008-01-29 14:51:59 +0100531 kobject_init(&q->kobj, &blk_queue_ktype);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532
Al Viro483f4af2006-03-18 18:34:37 -0500533 mutex_init(&q->sysfs_lock);
Neil Browne7e72bf2008-05-14 16:05:54 -0700534 spin_lock_init(&q->__queue_lock);
Al Viro483f4af2006-03-18 18:34:37 -0500535
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 return q;
537}
Christoph Lameter19460892005-06-23 00:08:19 -0700538EXPORT_SYMBOL(blk_alloc_queue_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539
540/**
541 * blk_init_queue - prepare a request queue for use with a block device
542 * @rfn: The function to be called to process requests that have been
543 * placed on the queue.
544 * @lock: Request queue spin lock
545 *
546 * Description:
547 * If a block device wishes to use the standard request handling procedures,
548 * which sorts requests and coalesces adjacent requests, then it must
549 * call blk_init_queue(). The function @rfn will be called when there
550 * are requests on the queue that need to be processed. If the device
551 * supports plugging, then @rfn may not be called immediately when requests
552 * are available on the queue, but may be called at some time later instead.
553 * Plugged queues are generally unplugged when a buffer belonging to one
554 * of the requests on the queue is needed, or due to memory pressure.
555 *
556 * @rfn is not required, or even expected, to remove all requests off the
557 * queue, but only as many as it can handle at a time. If it does leave
558 * requests on the queue, it is responsible for arranging that the requests
559 * get dealt with eventually.
560 *
561 * The queue spin lock must be held while manipulating the requests on the
Paolo 'Blaisorblade' Giarrussoa038e252006-06-05 12:09:01 +0200562 * request queue; this lock will be taken also from interrupt context, so irq
563 * disabling is needed for it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700564 *
Randy Dunlap710027a2008-08-19 20:13:11 +0200565 * Function returns a pointer to the initialized request queue, or %NULL if
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566 * it didn't succeed.
567 *
568 * Note:
569 * blk_init_queue() must be paired with a blk_cleanup_queue() call
570 * when the block device is deactivated (such as at module unload).
571 **/
Christoph Lameter19460892005-06-23 00:08:19 -0700572
Jens Axboe165125e2007-07-24 09:28:11 +0200573struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574{
Christoph Lameter19460892005-06-23 00:08:19 -0700575 return blk_init_queue_node(rfn, lock, -1);
576}
577EXPORT_SYMBOL(blk_init_queue);
578
Jens Axboe165125e2007-07-24 09:28:11 +0200579struct request_queue *
Christoph Lameter19460892005-06-23 00:08:19 -0700580blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
581{
Jens Axboe165125e2007-07-24 09:28:11 +0200582 struct request_queue *q = blk_alloc_queue_node(GFP_KERNEL, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583
584 if (!q)
585 return NULL;
586
Christoph Lameter19460892005-06-23 00:08:19 -0700587 q->node = node_id;
Al Viro8669aaf2006-03-18 13:50:00 -0500588 if (blk_init_free_list(q)) {
Jens Axboe8324aa92008-01-29 14:51:59 +0100589 kmem_cache_free(blk_requestq_cachep, q);
Al Viro8669aaf2006-03-18 13:50:00 -0500590 return NULL;
591 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592
152587d2005-04-12 16:22:06 -0500593 /*
594 * if caller didn't supply a lock, they get per-queue locking with
595 * our embedded lock
596 */
Neil Browne7e72bf2008-05-14 16:05:54 -0700597 if (!lock)
152587d2005-04-12 16:22:06 -0500598 lock = &q->__queue_lock;
152587d2005-04-12 16:22:06 -0500599
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600 q->request_fn = rfn;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601 q->prep_rq_fn = NULL;
602 q->unplug_fn = generic_unplug_device;
Jens Axboebc58ba92009-01-23 10:54:44 +0100603 q->queue_flags = QUEUE_FLAG_DEFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700604 q->queue_lock = lock;
605
Milan Broz0e435ac2008-12-03 12:55:08 +0100606 blk_queue_segment_boundary(q, BLK_SEG_BOUNDARY_MASK);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607
608 blk_queue_make_request(q, __make_request);
609 blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE);
610
611 blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
612 blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
613
Alan Stern44ec9542007-02-20 11:01:57 -0500614 q->sg_reserved_size = INT_MAX;
615
FUJITA Tomonoriabf54392008-08-16 14:10:05 +0900616 blk_set_cmd_filter_defaults(&q->cmd_filter);
617
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618 /*
619 * all done
620 */
621 if (!elevator_init(q, NULL)) {
622 blk_queue_congestion_threshold(q);
623 return q;
624 }
625
Al Viro8669aaf2006-03-18 13:50:00 -0500626 blk_put_queue(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627 return NULL;
628}
Christoph Lameter19460892005-06-23 00:08:19 -0700629EXPORT_SYMBOL(blk_init_queue_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630
Jens Axboe165125e2007-07-24 09:28:11 +0200631int blk_get_queue(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632{
Nick Pigginfde6ad22005-06-23 00:08:53 -0700633 if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
Al Viro483f4af2006-03-18 18:34:37 -0500634 kobject_get(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635 return 0;
636 }
637
638 return 1;
639}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700640
Jens Axboe165125e2007-07-24 09:28:11 +0200641static inline void blk_free_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642{
Jens Axboe4aff5e22006-08-10 08:44:47 +0200643 if (rq->cmd_flags & REQ_ELVPRIV)
Tejun Heocb98fc82005-10-28 08:29:39 +0200644 elv_put_request(q, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645 mempool_free(rq, q->rq.rq_pool);
646}
647
Jens Axboe1ea25ec2006-07-18 22:24:11 +0200648static struct request *
Jens Axboe165125e2007-07-24 09:28:11 +0200649blk_alloc_request(struct request_queue *q, int rw, int priv, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650{
651 struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask);
652
653 if (!rq)
654 return NULL;
655
FUJITA Tomonori2a4aa302008-04-29 09:54:36 +0200656 blk_rq_init(q, rq);
FUJITA Tomonori1afb20f2008-04-25 12:26:28 +0200657
Jens Axboe49171e52006-08-10 08:59:11 +0200658 rq->cmd_flags = rw | REQ_ALLOCED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659
Tejun Heocb98fc82005-10-28 08:29:39 +0200660 if (priv) {
Jens Axboecb78b282006-07-28 09:32:57 +0200661 if (unlikely(elv_set_request(q, rq, gfp_mask))) {
Tejun Heocb98fc82005-10-28 08:29:39 +0200662 mempool_free(rq, q->rq.rq_pool);
663 return NULL;
664 }
Jens Axboe4aff5e22006-08-10 08:44:47 +0200665 rq->cmd_flags |= REQ_ELVPRIV;
Tejun Heocb98fc82005-10-28 08:29:39 +0200666 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667
Tejun Heocb98fc82005-10-28 08:29:39 +0200668 return rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669}
670
671/*
672 * ioc_batching returns true if the ioc is a valid batching request and
673 * should be given priority access to a request.
674 */
Jens Axboe165125e2007-07-24 09:28:11 +0200675static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676{
677 if (!ioc)
678 return 0;
679
680 /*
681 * Make sure the process is able to allocate at least 1 request
682 * even if the batch times out, otherwise we could theoretically
683 * lose wakeups.
684 */
685 return ioc->nr_batch_requests == q->nr_batching ||
686 (ioc->nr_batch_requests > 0
687 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
688}
689
690/*
691 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
692 * will cause the process to be a "batcher" on all queues in the system. This
693 * is the behaviour we want though - once it gets a wakeup it should be given
694 * a nice run.
695 */
Jens Axboe165125e2007-07-24 09:28:11 +0200696static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697{
698 if (!ioc || ioc_batching(q, ioc))
699 return;
700
701 ioc->nr_batch_requests = q->nr_batching;
702 ioc->last_waited = jiffies;
703}
704
Jens Axboe165125e2007-07-24 09:28:11 +0200705static void __freed_request(struct request_queue *q, int rw)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706{
707 struct request_list *rl = &q->rq;
708
709 if (rl->count[rw] < queue_congestion_off_threshold(q))
Thomas Maier79e2de42006-10-19 23:28:15 -0700710 blk_clear_queue_congested(q, rw);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711
712 if (rl->count[rw] + 1 <= q->nr_requests) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700713 if (waitqueue_active(&rl->wait[rw]))
714 wake_up(&rl->wait[rw]);
715
716 blk_clear_queue_full(q, rw);
717 }
718}
719
720/*
721 * A request has just been released. Account for it, update the full and
722 * congestion status, wake up any waiters. Called under q->queue_lock.
723 */
Jens Axboe165125e2007-07-24 09:28:11 +0200724static void freed_request(struct request_queue *q, int rw, int priv)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725{
726 struct request_list *rl = &q->rq;
727
728 rl->count[rw]--;
Tejun Heocb98fc82005-10-28 08:29:39 +0200729 if (priv)
730 rl->elvpriv--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731
732 __freed_request(q, rw);
733
734 if (unlikely(rl->starved[rw ^ 1]))
735 __freed_request(q, rw ^ 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700736}
737
738#define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist)
739/*
Nick Piggind6344532005-06-28 20:45:14 -0700740 * Get a free request, queue_lock must be held.
741 * Returns NULL on failure, with queue_lock held.
742 * Returns !NULL on success, with queue_lock *not held*.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743 */
Jens Axboe165125e2007-07-24 09:28:11 +0200744static struct request *get_request(struct request_queue *q, int rw_flags,
Jens Axboe7749a8d2006-12-13 13:02:26 +0100745 struct bio *bio, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746{
747 struct request *rq = NULL;
748 struct request_list *rl = &q->rq;
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100749 struct io_context *ioc = NULL;
Jens Axboe7749a8d2006-12-13 13:02:26 +0100750 const int rw = rw_flags & 0x01;
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100751 int may_queue, priv;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752
Jens Axboe7749a8d2006-12-13 13:02:26 +0100753 may_queue = elv_may_queue(q, rw_flags);
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100754 if (may_queue == ELV_MQUEUE_NO)
755 goto rq_starved;
756
757 if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) {
758 if (rl->count[rw]+1 >= q->nr_requests) {
Jens Axboeb5deef92006-07-19 23:39:40 +0200759 ioc = current_io_context(GFP_ATOMIC, q->node);
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100760 /*
761 * The queue will fill after this allocation, so set
762 * it as full, and mark this process as "batching".
763 * This process will be allowed to complete a batch of
764 * requests, others will be blocked.
765 */
766 if (!blk_queue_full(q, rw)) {
767 ioc_set_batching(q, ioc);
768 blk_set_queue_full(q, rw);
769 } else {
770 if (may_queue != ELV_MQUEUE_MUST
771 && !ioc_batching(q, ioc)) {
772 /*
773 * The queue is full and the allocating
774 * process is not a "batcher", and not
775 * exempted by the IO scheduler
776 */
777 goto out;
778 }
779 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780 }
Thomas Maier79e2de42006-10-19 23:28:15 -0700781 blk_set_queue_congested(q, rw);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782 }
783
Jens Axboe082cf692005-06-28 16:35:11 +0200784 /*
785 * Only allow batching queuers to allocate up to 50% over the defined
786 * limit of requests, otherwise we could have thousands of requests
787 * allocated with any setting of ->nr_requests
788 */
Hugh Dickinsfd782a42005-06-29 15:15:40 +0100789 if (rl->count[rw] >= (3 * q->nr_requests / 2))
Jens Axboe082cf692005-06-28 16:35:11 +0200790 goto out;
Hugh Dickinsfd782a42005-06-29 15:15:40 +0100791
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792 rl->count[rw]++;
793 rl->starved[rw] = 0;
Tejun Heocb98fc82005-10-28 08:29:39 +0200794
Jens Axboe64521d12005-10-28 08:30:39 +0200795 priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
Tejun Heocb98fc82005-10-28 08:29:39 +0200796 if (priv)
797 rl->elvpriv++;
798
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799 spin_unlock_irq(q->queue_lock);
800
Jens Axboe7749a8d2006-12-13 13:02:26 +0100801 rq = blk_alloc_request(q, rw_flags, priv, gfp_mask);
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100802 if (unlikely(!rq)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700803 /*
804 * Allocation failed presumably due to memory. Undo anything
805 * we might have messed up.
806 *
807 * Allocating task should really be put onto the front of the
808 * wait queue, but this is pretty rare.
809 */
810 spin_lock_irq(q->queue_lock);
Tejun Heocb98fc82005-10-28 08:29:39 +0200811 freed_request(q, rw, priv);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812
813 /*
814 * in the very unlikely event that allocation failed and no
815 * requests for this direction was pending, mark us starved
816 * so that freeing of a request in the other direction will
817 * notice us. another possible fix would be to split the
818 * rq mempool into READ and WRITE
819 */
820rq_starved:
821 if (unlikely(rl->count[rw] == 0))
822 rl->starved[rw] = 1;
823
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824 goto out;
825 }
826
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100827 /*
828 * ioc may be NULL here, and ioc_batching will be false. That's
829 * OK, if the queue is under the request limit then requests need
830 * not count toward the nr_batch_requests limit. There will always
831 * be some limit enforced by BLK_BATCH_TIME.
832 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700833 if (ioc_batching(q, ioc))
834 ioc->nr_batch_requests--;
Jens Axboe6728cb02008-01-31 13:03:55 +0100835
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +0100836 trace_block_getrq(q, bio, rw);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700837out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838 return rq;
839}
840
841/*
842 * No available requests for this queue, unplug the device and wait for some
843 * requests to become available.
Nick Piggind6344532005-06-28 20:45:14 -0700844 *
845 * Called with q->queue_lock held, and returns with it unlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700846 */
Jens Axboe165125e2007-07-24 09:28:11 +0200847static struct request *get_request_wait(struct request_queue *q, int rw_flags,
Jens Axboe22e2c502005-06-27 10:55:12 +0200848 struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700849{
Jens Axboe7749a8d2006-12-13 13:02:26 +0100850 const int rw = rw_flags & 0x01;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851 struct request *rq;
852
Jens Axboe7749a8d2006-12-13 13:02:26 +0100853 rq = get_request(q, rw_flags, bio, GFP_NOIO);
Nick Piggin450991b2005-06-28 20:45:13 -0700854 while (!rq) {
855 DEFINE_WAIT(wait);
Zhang, Yanmin05caf8d2008-05-22 15:13:29 +0200856 struct io_context *ioc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857 struct request_list *rl = &q->rq;
858
859 prepare_to_wait_exclusive(&rl->wait[rw], &wait,
860 TASK_UNINTERRUPTIBLE);
861
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +0100862 trace_block_sleeprq(q, bio, rw);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863
Zhang, Yanmin05caf8d2008-05-22 15:13:29 +0200864 __generic_unplug_device(q);
865 spin_unlock_irq(q->queue_lock);
866 io_schedule();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700867
Zhang, Yanmin05caf8d2008-05-22 15:13:29 +0200868 /*
869 * After sleeping, we become a "batching" process and
870 * will be able to allocate at least one request, and
871 * up to a big batch of them for a small period time.
872 * See ioc_batching, ioc_set_batching
873 */
874 ioc = current_io_context(GFP_NOIO, q->node);
875 ioc_set_batching(q, ioc);
Jens Axboe2056a782006-03-23 20:00:26 +0100876
Zhang, Yanmin05caf8d2008-05-22 15:13:29 +0200877 spin_lock_irq(q->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700878 finish_wait(&rl->wait[rw], &wait);
Zhang, Yanmin05caf8d2008-05-22 15:13:29 +0200879
880 rq = get_request(q, rw_flags, bio, GFP_NOIO);
881 };
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882
883 return rq;
884}
885
Jens Axboe165125e2007-07-24 09:28:11 +0200886struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887{
888 struct request *rq;
889
890 BUG_ON(rw != READ && rw != WRITE);
891
Nick Piggind6344532005-06-28 20:45:14 -0700892 spin_lock_irq(q->queue_lock);
893 if (gfp_mask & __GFP_WAIT) {
Jens Axboe22e2c502005-06-27 10:55:12 +0200894 rq = get_request_wait(q, rw, NULL);
Nick Piggind6344532005-06-28 20:45:14 -0700895 } else {
Jens Axboe22e2c502005-06-27 10:55:12 +0200896 rq = get_request(q, rw, NULL, gfp_mask);
Nick Piggind6344532005-06-28 20:45:14 -0700897 if (!rq)
898 spin_unlock_irq(q->queue_lock);
899 }
900 /* q->queue_lock is unlocked at this point */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901
902 return rq;
903}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904EXPORT_SYMBOL(blk_get_request);
905
906/**
Jens Axboedc72ef42006-07-20 14:54:05 +0200907 * blk_start_queueing - initiate dispatch of requests to device
908 * @q: request queue to kick into gear
909 *
910 * This is basically a helper to remove the need to know whether a queue
911 * is plugged or not if someone just wants to initiate dispatch of requests
Jens Axboe80a4b582008-10-14 09:51:06 +0200912 * for this queue. Should be used to start queueing on a device outside
913 * of ->request_fn() context. Also see @blk_run_queue.
Jens Axboedc72ef42006-07-20 14:54:05 +0200914 *
915 * The queue lock must be held with interrupts disabled.
916 */
Jens Axboe165125e2007-07-24 09:28:11 +0200917void blk_start_queueing(struct request_queue *q)
Jens Axboedc72ef42006-07-20 14:54:05 +0200918{
Elias Oltmanns336c3d82008-10-01 16:02:33 +0200919 if (!blk_queue_plugged(q)) {
920 if (unlikely(blk_queue_stopped(q)))
921 return;
Jens Axboedc72ef42006-07-20 14:54:05 +0200922 q->request_fn(q);
Elias Oltmanns336c3d82008-10-01 16:02:33 +0200923 } else
Jens Axboedc72ef42006-07-20 14:54:05 +0200924 __generic_unplug_device(q);
925}
926EXPORT_SYMBOL(blk_start_queueing);
927
928/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929 * blk_requeue_request - put a request back on queue
930 * @q: request queue where request should be inserted
931 * @rq: request to be inserted
932 *
933 * Description:
934 * Drivers often keep queueing requests until the hardware cannot accept
935 * more, when that condition happens we need to put the request back
936 * on the queue. Must be called with queue lock held.
937 */
Jens Axboe165125e2007-07-24 09:28:11 +0200938void blk_requeue_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700939{
Jens Axboe242f9dc2008-09-14 05:55:09 -0700940 blk_delete_timer(rq);
941 blk_clear_rq_complete(rq);
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +0100942 trace_block_rq_requeue(q, rq);
Jens Axboe2056a782006-03-23 20:00:26 +0100943
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944 if (blk_rq_tagged(rq))
945 blk_queue_end_tag(q, rq);
946
947 elv_requeue_request(q, rq);
948}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700949EXPORT_SYMBOL(blk_requeue_request);
950
951/**
Randy Dunlap710027a2008-08-19 20:13:11 +0200952 * blk_insert_request - insert a special request into a request queue
Linus Torvalds1da177e2005-04-16 15:20:36 -0700953 * @q: request queue where request should be inserted
954 * @rq: request to be inserted
955 * @at_head: insert request at head or tail of queue
956 * @data: private data
Linus Torvalds1da177e2005-04-16 15:20:36 -0700957 *
958 * Description:
959 * Many block devices need to execute commands asynchronously, so they don't
960 * block the whole kernel from preemption during request execution. This is
961 * accomplished normally by inserting aritficial requests tagged as
Randy Dunlap710027a2008-08-19 20:13:11 +0200962 * REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them
963 * be scheduled for actual execution by the request queue.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964 *
965 * We have the option of inserting the head or the tail of the queue.
966 * Typically we use the tail for new ioctls and so forth. We use the head
967 * of the queue for things like a QUEUE_FULL message from a device, or a
968 * host that is unable to accept a particular command.
969 */
Jens Axboe165125e2007-07-24 09:28:11 +0200970void blk_insert_request(struct request_queue *q, struct request *rq,
Tejun Heo 867d1192005-04-24 02:06:05 -0500971 int at_head, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700972{
Tejun Heo 867d1192005-04-24 02:06:05 -0500973 int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974 unsigned long flags;
975
976 /*
977 * tell I/O scheduler that this isn't a regular read/write (ie it
978 * must not attempt merges on this) and that it acts as a soft
979 * barrier
980 */
Jens Axboe4aff5e22006-08-10 08:44:47 +0200981 rq->cmd_type = REQ_TYPE_SPECIAL;
982 rq->cmd_flags |= REQ_SOFTBARRIER;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983
984 rq->special = data;
985
986 spin_lock_irqsave(q->queue_lock, flags);
987
988 /*
989 * If command is tagged, release the tag
990 */
Tejun Heo 867d1192005-04-24 02:06:05 -0500991 if (blk_rq_tagged(rq))
992 blk_queue_end_tag(q, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700993
Jerome Marchandb238b3d2007-10-23 15:05:46 +0200994 drive_stat_acct(rq, 1);
Tejun Heo 867d1192005-04-24 02:06:05 -0500995 __elv_add_request(q, rq, where, 0);
Jens Axboedc72ef42006-07-20 14:54:05 +0200996 blk_start_queueing(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997 spin_unlock_irqrestore(q->queue_lock, flags);
998}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999EXPORT_SYMBOL(blk_insert_request);
1000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001001/*
1002 * add-request adds a request to the linked list.
1003 * queue lock is held and interrupts disabled, as we muck with the
1004 * request queue list.
1005 */
Jens Axboe6728cb02008-01-31 13:03:55 +01001006static inline void add_request(struct request_queue *q, struct request *req)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001007{
Jerome Marchandb238b3d2007-10-23 15:05:46 +02001008 drive_stat_acct(req, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001009
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010 /*
1011 * elevator indicated where it wants this request to be
1012 * inserted at elevator_merge time
1013 */
1014 __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0);
1015}
Jens Axboe6728cb02008-01-31 13:03:55 +01001016
Tejun Heo074a7ac2008-08-25 19:56:14 +09001017static void part_round_stats_single(int cpu, struct hd_struct *part,
1018 unsigned long now)
1019{
1020 if (now == part->stamp)
1021 return;
1022
1023 if (part->in_flight) {
1024 __part_stat_add(cpu, part, time_in_queue,
1025 part->in_flight * (now - part->stamp));
1026 __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
1027 }
1028 part->stamp = now;
1029}
1030
1031/**
Randy Dunlap496aa8a2008-10-16 07:46:23 +02001032 * part_round_stats() - Round off the performance stats on a struct disk_stats.
1033 * @cpu: cpu number for stats access
1034 * @part: target partition
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035 *
1036 * The average IO queue length and utilisation statistics are maintained
1037 * by observing the current state of the queue length and the amount of
1038 * time it has been in this state for.
1039 *
1040 * Normally, that accounting is done on IO completion, but that can result
1041 * in more than a second's worth of IO being accounted for within any one
1042 * second, leading to >100% utilisation. To deal with that, we call this
1043 * function to do a round-off before returning the results when reading
1044 * /proc/diskstats. This accounts immediately for all queue usage up to
1045 * the current jiffies and restarts the counters again.
1046 */
Tejun Heoc9959052008-08-25 19:47:21 +09001047void part_round_stats(int cpu, struct hd_struct *part)
Jerome Marchand6f2576a2008-02-08 11:04:35 +01001048{
1049 unsigned long now = jiffies;
1050
Tejun Heo074a7ac2008-08-25 19:56:14 +09001051 if (part->partno)
1052 part_round_stats_single(cpu, &part_to_disk(part)->part0, now);
1053 part_round_stats_single(cpu, part, now);
Jerome Marchand6f2576a2008-02-08 11:04:35 +01001054}
Tejun Heo074a7ac2008-08-25 19:56:14 +09001055EXPORT_SYMBOL_GPL(part_round_stats);
Jerome Marchand6f2576a2008-02-08 11:04:35 +01001056
Linus Torvalds1da177e2005-04-16 15:20:36 -07001057/*
1058 * queue lock must be held
1059 */
Jens Axboe165125e2007-07-24 09:28:11 +02001060void __blk_put_request(struct request_queue *q, struct request *req)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062 if (unlikely(!q))
1063 return;
1064 if (unlikely(--req->ref_count))
1065 return;
1066
Tejun Heo8922e162005-10-20 16:23:44 +02001067 elv_completed_request(q, req);
1068
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069 /*
1070 * Request may not have originated from ll_rw_blk. if not,
1071 * it didn't come out of our reserved rq pools
1072 */
Jens Axboe49171e52006-08-10 08:59:11 +02001073 if (req->cmd_flags & REQ_ALLOCED) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001074 int rw = rq_data_dir(req);
Jens Axboe4aff5e22006-08-10 08:44:47 +02001075 int priv = req->cmd_flags & REQ_ELVPRIV;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001076
Linus Torvalds1da177e2005-04-16 15:20:36 -07001077 BUG_ON(!list_empty(&req->queuelist));
Jens Axboe98170642006-07-28 09:23:08 +02001078 BUG_ON(!hlist_unhashed(&req->hash));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079
1080 blk_free_request(q, req);
Tejun Heocb98fc82005-10-28 08:29:39 +02001081 freed_request(q, rw, priv);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001082 }
1083}
Mike Christie6e39b692005-11-11 05:30:24 -06001084EXPORT_SYMBOL_GPL(__blk_put_request);
1085
Linus Torvalds1da177e2005-04-16 15:20:36 -07001086void blk_put_request(struct request *req)
1087{
Tejun Heo8922e162005-10-20 16:23:44 +02001088 unsigned long flags;
Jens Axboe165125e2007-07-24 09:28:11 +02001089 struct request_queue *q = req->q;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001090
FUJITA Tomonori52a93ba2008-07-15 21:21:45 +02001091 spin_lock_irqsave(q->queue_lock, flags);
1092 __blk_put_request(q, req);
1093 spin_unlock_irqrestore(q->queue_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001094}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095EXPORT_SYMBOL(blk_put_request);
1096
Jens Axboe86db1e22008-01-29 14:53:40 +01001097void init_request_from_bio(struct request *req, struct bio *bio)
Tejun Heo52d9e672006-01-06 09:49:58 +01001098{
Jens Axboec7c22e42008-09-13 20:26:01 +02001099 req->cpu = bio->bi_comp_cpu;
Jens Axboe4aff5e22006-08-10 08:44:47 +02001100 req->cmd_type = REQ_TYPE_FS;
Tejun Heo52d9e672006-01-06 09:49:58 +01001101
1102 /*
1103 * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
1104 */
Mike Christie6000a362008-08-19 18:45:30 -05001105 if (bio_rw_ahead(bio))
1106 req->cmd_flags |= (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
1107 REQ_FAILFAST_DRIVER);
1108 if (bio_failfast_dev(bio))
1109 req->cmd_flags |= REQ_FAILFAST_DEV;
1110 if (bio_failfast_transport(bio))
1111 req->cmd_flags |= REQ_FAILFAST_TRANSPORT;
1112 if (bio_failfast_driver(bio))
1113 req->cmd_flags |= REQ_FAILFAST_DRIVER;
Tejun Heo52d9e672006-01-06 09:49:58 +01001114
1115 /*
1116 * REQ_BARRIER implies no merging, but lets make it explicit
1117 */
David Woodhousefb2dce82008-08-05 18:01:53 +01001118 if (unlikely(bio_discard(bio))) {
David Woodhousee17fc0a2008-08-09 16:42:20 +01001119 req->cmd_flags |= REQ_DISCARD;
1120 if (bio_barrier(bio))
1121 req->cmd_flags |= REQ_SOFTBARRIER;
David Woodhousefb2dce82008-08-05 18:01:53 +01001122 req->q->prepare_discard_fn(req->q, req);
David Woodhousee17fc0a2008-08-09 16:42:20 +01001123 } else if (unlikely(bio_barrier(bio)))
1124 req->cmd_flags |= (REQ_HARDBARRIER | REQ_NOMERGE);
Tejun Heo52d9e672006-01-06 09:49:58 +01001125
Jens Axboeb31dc662006-06-13 08:26:10 +02001126 if (bio_sync(bio))
Jens Axboe4aff5e22006-08-10 08:44:47 +02001127 req->cmd_flags |= REQ_RW_SYNC;
Jens Axboe213d9412009-01-06 09:16:05 +01001128 if (bio_unplug(bio))
1129 req->cmd_flags |= REQ_UNPLUG;
Jens Axboe5404bc72006-08-10 09:01:02 +02001130 if (bio_rw_meta(bio))
1131 req->cmd_flags |= REQ_RW_META;
Jens Axboeb31dc662006-06-13 08:26:10 +02001132
Tejun Heo52d9e672006-01-06 09:49:58 +01001133 req->errors = 0;
1134 req->hard_sector = req->sector = bio->bi_sector;
Tejun Heo52d9e672006-01-06 09:49:58 +01001135 req->ioprio = bio_prio(bio);
Tejun Heo52d9e672006-01-06 09:49:58 +01001136 req->start_time = jiffies;
NeilBrownbc1c56f2007-08-16 13:31:30 +02001137 blk_rq_bio_prep(req->q, req, bio);
Tejun Heo52d9e672006-01-06 09:49:58 +01001138}
1139
Jens Axboe165125e2007-07-24 09:28:11 +02001140static int __make_request(struct request_queue *q, struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141{
Nick Piggin450991b2005-06-28 20:45:13 -07001142 struct request *req;
Tejun Heoa7384672008-11-28 13:32:03 +09001143 int el_ret, nr_sectors;
Jens Axboe51da90f2006-07-18 04:14:45 +02001144 const unsigned short prio = bio_prio(bio);
1145 const int sync = bio_sync(bio);
Jens Axboe213d9412009-01-06 09:16:05 +01001146 const int unplug = bio_unplug(bio);
Jens Axboe7749a8d2006-12-13 13:02:26 +01001147 int rw_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001148
Linus Torvalds1da177e2005-04-16 15:20:36 -07001149 nr_sectors = bio_sectors(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001150
1151 /*
1152 * low level driver can indicate that it wants pages above a
1153 * certain limit bounced to low memory (ie for highmem, or even
1154 * ISA dma in theory)
1155 */
1156 blk_queue_bounce(q, &bio);
1157
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158 spin_lock_irq(q->queue_lock);
1159
Tejun Heoa7384672008-11-28 13:32:03 +09001160 if (unlikely(bio_barrier(bio)) || elv_queue_empty(q))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001161 goto get_rq;
1162
1163 el_ret = elv_merge(q, &req, bio);
1164 switch (el_ret) {
Jens Axboe6728cb02008-01-31 13:03:55 +01001165 case ELEVATOR_BACK_MERGE:
1166 BUG_ON(!rq_mergeable(req));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001167
Jens Axboe6728cb02008-01-31 13:03:55 +01001168 if (!ll_back_merge_fn(q, req, bio))
1169 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001170
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +01001171 trace_block_bio_backmerge(q, bio);
Jens Axboe2056a782006-03-23 20:00:26 +01001172
Jens Axboe6728cb02008-01-31 13:03:55 +01001173 req->biotail->bi_next = bio;
1174 req->biotail = bio;
1175 req->nr_sectors = req->hard_nr_sectors += nr_sectors;
1176 req->ioprio = ioprio_best(req->ioprio, prio);
Jens Axboeab780f12008-08-26 10:25:02 +02001177 if (!blk_rq_cpu_valid(req))
1178 req->cpu = bio->bi_comp_cpu;
Jens Axboe6728cb02008-01-31 13:03:55 +01001179 drive_stat_acct(req, 0);
1180 if (!attempt_back_merge(q, req))
1181 elv_merged_request(q, req, el_ret);
1182 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001183
Jens Axboe6728cb02008-01-31 13:03:55 +01001184 case ELEVATOR_FRONT_MERGE:
1185 BUG_ON(!rq_mergeable(req));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001186
Jens Axboe6728cb02008-01-31 13:03:55 +01001187 if (!ll_front_merge_fn(q, req, bio))
1188 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001189
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +01001190 trace_block_bio_frontmerge(q, bio);
Jens Axboe2056a782006-03-23 20:00:26 +01001191
Jens Axboe6728cb02008-01-31 13:03:55 +01001192 bio->bi_next = req->bio;
1193 req->bio = bio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001194
Jens Axboe6728cb02008-01-31 13:03:55 +01001195 /*
1196 * may not be valid. if the low level driver said
1197 * it didn't need a bounce buffer then it better
1198 * not touch req->buffer either...
1199 */
1200 req->buffer = bio_data(bio);
1201 req->current_nr_sectors = bio_cur_sectors(bio);
1202 req->hard_cur_sectors = req->current_nr_sectors;
1203 req->sector = req->hard_sector = bio->bi_sector;
1204 req->nr_sectors = req->hard_nr_sectors += nr_sectors;
1205 req->ioprio = ioprio_best(req->ioprio, prio);
Jens Axboeab780f12008-08-26 10:25:02 +02001206 if (!blk_rq_cpu_valid(req))
1207 req->cpu = bio->bi_comp_cpu;
Jens Axboe6728cb02008-01-31 13:03:55 +01001208 drive_stat_acct(req, 0);
1209 if (!attempt_front_merge(q, req))
1210 elv_merged_request(q, req, el_ret);
1211 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212
Jens Axboe6728cb02008-01-31 13:03:55 +01001213 /* ELV_NO_MERGE: elevator says don't/can't merge. */
1214 default:
1215 ;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216 }
1217
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218get_rq:
Nick Piggin450991b2005-06-28 20:45:13 -07001219 /*
Jens Axboe7749a8d2006-12-13 13:02:26 +01001220 * This sync check and mask will be re-done in init_request_from_bio(),
1221 * but we need to set it earlier to expose the sync flag to the
1222 * rq allocator and io schedulers.
1223 */
1224 rw_flags = bio_data_dir(bio);
1225 if (sync)
1226 rw_flags |= REQ_RW_SYNC;
1227
1228 /*
Nick Piggin450991b2005-06-28 20:45:13 -07001229 * Grab a free request. This is might sleep but can not fail.
Nick Piggind6344532005-06-28 20:45:14 -07001230 * Returns with the queue unlocked.
Nick Piggin450991b2005-06-28 20:45:13 -07001231 */
Jens Axboe7749a8d2006-12-13 13:02:26 +01001232 req = get_request_wait(q, rw_flags, bio);
Nick Piggind6344532005-06-28 20:45:14 -07001233
Nick Piggin450991b2005-06-28 20:45:13 -07001234 /*
1235 * After dropping the lock and possibly sleeping here, our request
1236 * may now be mergeable after it had proven unmergeable (above).
1237 * We don't worry about that case for efficiency. It won't happen
1238 * often, and the elevators are able to handle it.
1239 */
Tejun Heo52d9e672006-01-06 09:49:58 +01001240 init_request_from_bio(req, bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001241
Nick Piggin450991b2005-06-28 20:45:13 -07001242 spin_lock_irq(q->queue_lock);
Jens Axboec7c22e42008-09-13 20:26:01 +02001243 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) ||
1244 bio_flagged(bio, BIO_CPU_AFFINE))
1245 req->cpu = blk_cpu_to_group(smp_processor_id());
Jens Axboea31a9732008-10-17 13:58:29 +02001246 if (!blk_queue_nonrot(q) && elv_queue_empty(q))
Nick Piggin450991b2005-06-28 20:45:13 -07001247 blk_plug_device(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001248 add_request(q, req);
1249out:
Jens Axboe213d9412009-01-06 09:16:05 +01001250 if (unplug || blk_queue_nonrot(q))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001251 __generic_unplug_device(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001252 spin_unlock_irq(q->queue_lock);
1253 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001254}
1255
1256/*
1257 * If bio->bi_dev is a partition, remap the location
1258 */
1259static inline void blk_partition_remap(struct bio *bio)
1260{
1261 struct block_device *bdev = bio->bi_bdev;
1262
Jens Axboebf2de6f2007-09-27 13:01:25 +02001263 if (bio_sectors(bio) && bdev != bdev->bd_contains) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001264 struct hd_struct *p = bdev->bd_part;
Jens Axboea3623572005-11-01 09:26:16 +01001265
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266 bio->bi_sector += p->start_sect;
1267 bio->bi_bdev = bdev->bd_contains;
Alan D. Brunellec7149d62007-08-07 15:30:23 +02001268
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +01001269 trace_block_remap(bdev_get_queue(bio->bi_bdev), bio,
Alan D. Brunellec7149d62007-08-07 15:30:23 +02001270 bdev->bd_dev, bio->bi_sector,
1271 bio->bi_sector - p->start_sect);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272 }
1273}
1274
Linus Torvalds1da177e2005-04-16 15:20:36 -07001275static void handle_bad_sector(struct bio *bio)
1276{
1277 char b[BDEVNAME_SIZE];
1278
1279 printk(KERN_INFO "attempt to access beyond end of device\n");
1280 printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
1281 bdevname(bio->bi_bdev, b),
1282 bio->bi_rw,
1283 (unsigned long long)bio->bi_sector + bio_sectors(bio),
1284 (long long)(bio->bi_bdev->bd_inode->i_size >> 9));
1285
1286 set_bit(BIO_EOF, &bio->bi_flags);
1287}
1288
Akinobu Mitac17bb492006-12-08 02:39:46 -08001289#ifdef CONFIG_FAIL_MAKE_REQUEST
1290
1291static DECLARE_FAULT_ATTR(fail_make_request);
1292
1293static int __init setup_fail_make_request(char *str)
1294{
1295 return setup_fault_attr(&fail_make_request, str);
1296}
1297__setup("fail_make_request=", setup_fail_make_request);
1298
1299static int should_fail_request(struct bio *bio)
1300{
Tejun Heoeddb2e22008-08-25 19:56:13 +09001301 struct hd_struct *part = bio->bi_bdev->bd_part;
1302
1303 if (part_to_disk(part)->part0.make_it_fail || part->make_it_fail)
Akinobu Mitac17bb492006-12-08 02:39:46 -08001304 return should_fail(&fail_make_request, bio->bi_size);
1305
1306 return 0;
1307}
1308
1309static int __init fail_make_request_debugfs(void)
1310{
1311 return init_fault_attr_dentries(&fail_make_request,
1312 "fail_make_request");
1313}
1314
1315late_initcall(fail_make_request_debugfs);
1316
1317#else /* CONFIG_FAIL_MAKE_REQUEST */
1318
1319static inline int should_fail_request(struct bio *bio)
1320{
1321 return 0;
1322}
1323
1324#endif /* CONFIG_FAIL_MAKE_REQUEST */
1325
Jens Axboec07e2b42007-07-18 13:27:58 +02001326/*
1327 * Check whether this bio extends beyond the end of the device.
1328 */
1329static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
1330{
1331 sector_t maxsector;
1332
1333 if (!nr_sectors)
1334 return 0;
1335
1336 /* Test device or partition size, when known. */
1337 maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
1338 if (maxsector) {
1339 sector_t sector = bio->bi_sector;
1340
1341 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
1342 /*
1343 * This may well happen - the kernel calls bread()
1344 * without checking the size of the device, e.g., when
1345 * mounting a device.
1346 */
1347 handle_bad_sector(bio);
1348 return 1;
1349 }
1350 }
1351
1352 return 0;
1353}
1354
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355/**
Randy Dunlap710027a2008-08-19 20:13:11 +02001356 * generic_make_request - hand a buffer to its device driver for I/O
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357 * @bio: The bio describing the location in memory and on the device.
1358 *
1359 * generic_make_request() is used to make I/O requests of block
1360 * devices. It is passed a &struct bio, which describes the I/O that needs
1361 * to be done.
1362 *
1363 * generic_make_request() does not return any status. The
1364 * success/failure status of the request, along with notification of
1365 * completion, is delivered asynchronously through the bio->bi_end_io
1366 * function described (one day) else where.
1367 *
1368 * The caller of generic_make_request must make sure that bi_io_vec
1369 * are set to describe the memory buffer, and that bi_dev and bi_sector are
1370 * set to describe the device address, and the
1371 * bi_end_io and optionally bi_private are set to describe how
1372 * completion notification should be signaled.
1373 *
1374 * generic_make_request and the drivers it calls may use bi_next if this
1375 * bio happens to be merged with someone else, and may change bi_dev and
1376 * bi_sector for remaps as it sees fit. So the values of these fields
1377 * should NOT be depended on after the call to generic_make_request.
1378 */
Neil Brownd89d8792007-05-01 09:53:42 +02001379static inline void __generic_make_request(struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380{
Jens Axboe165125e2007-07-24 09:28:11 +02001381 struct request_queue *q;
NeilBrown5ddfe962006-10-30 22:07:21 -08001382 sector_t old_sector;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383 int ret, nr_sectors = bio_sectors(bio);
Jens Axboe2056a782006-03-23 20:00:26 +01001384 dev_t old_dev;
Jens Axboe51fd77b2007-11-02 08:49:08 +01001385 int err = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386
1387 might_sleep();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001388
Jens Axboec07e2b42007-07-18 13:27:58 +02001389 if (bio_check_eod(bio, nr_sectors))
1390 goto end_io;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391
1392 /*
1393 * Resolve the mapping until finished. (drivers are
1394 * still free to implement/resolve their own stacking
1395 * by explicitly returning 0)
1396 *
1397 * NOTE: we don't repeat the blk_size check for each new device.
1398 * Stacking drivers are expected to know what they are doing.
1399 */
NeilBrown5ddfe962006-10-30 22:07:21 -08001400 old_sector = -1;
Jens Axboe2056a782006-03-23 20:00:26 +01001401 old_dev = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001402 do {
1403 char b[BDEVNAME_SIZE];
1404
1405 q = bdev_get_queue(bio->bi_bdev);
Tejun Heoa7384672008-11-28 13:32:03 +09001406 if (unlikely(!q)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001407 printk(KERN_ERR
1408 "generic_make_request: Trying to access "
1409 "nonexistent block-device %s (%Lu)\n",
1410 bdevname(bio->bi_bdev, b),
1411 (long long) bio->bi_sector);
Tejun Heoa7384672008-11-28 13:32:03 +09001412 goto end_io;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001413 }
1414
Jens Axboe4fa253f2007-07-18 13:13:10 +02001415 if (unlikely(nr_sectors > q->max_hw_sectors)) {
Jens Axboe6728cb02008-01-31 13:03:55 +01001416 printk(KERN_ERR "bio too big device %s (%u > %u)\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001417 bdevname(bio->bi_bdev, b),
1418 bio_sectors(bio),
1419 q->max_hw_sectors);
1420 goto end_io;
1421 }
1422
Nick Pigginfde6ad22005-06-23 00:08:53 -07001423 if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424 goto end_io;
1425
Akinobu Mitac17bb492006-12-08 02:39:46 -08001426 if (should_fail_request(bio))
1427 goto end_io;
1428
Linus Torvalds1da177e2005-04-16 15:20:36 -07001429 /*
1430 * If this device has partitions, remap block n
1431 * of partition p to block n+start(p) of the disk.
1432 */
1433 blk_partition_remap(bio);
1434
Martin K. Petersen7ba1ba12008-06-30 20:04:41 +02001435 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio))
1436 goto end_io;
1437
NeilBrown5ddfe962006-10-30 22:07:21 -08001438 if (old_sector != -1)
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +01001439 trace_block_remap(q, bio, old_dev, bio->bi_sector,
NeilBrown5ddfe962006-10-30 22:07:21 -08001440 old_sector);
Jens Axboe2056a782006-03-23 20:00:26 +01001441
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +01001442 trace_block_bio_queue(q, bio);
Jens Axboe2056a782006-03-23 20:00:26 +01001443
NeilBrown5ddfe962006-10-30 22:07:21 -08001444 old_sector = bio->bi_sector;
Jens Axboe2056a782006-03-23 20:00:26 +01001445 old_dev = bio->bi_bdev->bd_dev;
1446
Jens Axboec07e2b42007-07-18 13:27:58 +02001447 if (bio_check_eod(bio, nr_sectors))
1448 goto end_io;
Tejun Heoa7384672008-11-28 13:32:03 +09001449
1450 if (bio_discard(bio) && !q->prepare_discard_fn) {
Jens Axboe51fd77b2007-11-02 08:49:08 +01001451 err = -EOPNOTSUPP;
1452 goto end_io;
1453 }
Jens Axboecec07072009-01-13 15:28:32 +01001454 if (bio_barrier(bio) && bio_has_data(bio) &&
1455 (q->next_ordered == QUEUE_ORDERED_NONE)) {
1456 err = -EOPNOTSUPP;
1457 goto end_io;
1458 }
NeilBrown5ddfe962006-10-30 22:07:21 -08001459
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460 ret = q->make_request_fn(q, bio);
1461 } while (ret);
Tejun Heoa7384672008-11-28 13:32:03 +09001462
1463 return;
1464
1465end_io:
1466 bio_endio(bio, err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001467}
1468
Neil Brownd89d8792007-05-01 09:53:42 +02001469/*
1470 * We only want one ->make_request_fn to be active at a time,
1471 * else stack usage with stacked devices could be a problem.
1472 * So use current->bio_{list,tail} to keep a list of requests
1473 * submited by a make_request_fn function.
1474 * current->bio_tail is also used as a flag to say if
1475 * generic_make_request is currently active in this task or not.
1476 * If it is NULL, then no make_request is active. If it is non-NULL,
1477 * then a make_request is active, and new requests should be added
1478 * at the tail
1479 */
1480void generic_make_request(struct bio *bio)
1481{
1482 if (current->bio_tail) {
1483 /* make_request is active */
1484 *(current->bio_tail) = bio;
1485 bio->bi_next = NULL;
1486 current->bio_tail = &bio->bi_next;
1487 return;
1488 }
1489 /* following loop may be a bit non-obvious, and so deserves some
1490 * explanation.
1491 * Before entering the loop, bio->bi_next is NULL (as all callers
1492 * ensure that) so we have a list with a single bio.
1493 * We pretend that we have just taken it off a longer list, so
1494 * we assign bio_list to the next (which is NULL) and bio_tail
1495 * to &bio_list, thus initialising the bio_list of new bios to be
1496 * added. __generic_make_request may indeed add some more bios
1497 * through a recursive call to generic_make_request. If it
1498 * did, we find a non-NULL value in bio_list and re-enter the loop
1499 * from the top. In this case we really did just take the bio
1500 * of the top of the list (no pretending) and so fixup bio_list and
1501 * bio_tail or bi_next, and call into __generic_make_request again.
1502 *
1503 * The loop was structured like this to make only one call to
1504 * __generic_make_request (which is important as it is large and
1505 * inlined) and to keep the structure simple.
1506 */
1507 BUG_ON(bio->bi_next);
1508 do {
1509 current->bio_list = bio->bi_next;
1510 if (bio->bi_next == NULL)
1511 current->bio_tail = &current->bio_list;
1512 else
1513 bio->bi_next = NULL;
1514 __generic_make_request(bio);
1515 bio = current->bio_list;
1516 } while (bio);
1517 current->bio_tail = NULL; /* deactivate */
1518}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001519EXPORT_SYMBOL(generic_make_request);
1520
1521/**
Randy Dunlap710027a2008-08-19 20:13:11 +02001522 * submit_bio - submit a bio to the block device layer for I/O
Linus Torvalds1da177e2005-04-16 15:20:36 -07001523 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
1524 * @bio: The &struct bio which describes the I/O
1525 *
1526 * submit_bio() is very similar in purpose to generic_make_request(), and
1527 * uses that function to do most of the work. Both are fairly rough
Randy Dunlap710027a2008-08-19 20:13:11 +02001528 * interfaces; @bio must be presetup and ready for I/O.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001529 *
1530 */
1531void submit_bio(int rw, struct bio *bio)
1532{
1533 int count = bio_sectors(bio);
1534
Jens Axboe22e2c502005-06-27 10:55:12 +02001535 bio->bi_rw |= rw;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536
Jens Axboebf2de6f2007-09-27 13:01:25 +02001537 /*
1538 * If it's a regular read/write or a barrier with data attached,
1539 * go through the normal accounting stuff before submission.
1540 */
Jens Axboea9c701e2008-08-08 11:04:44 +02001541 if (bio_has_data(bio)) {
Jens Axboebf2de6f2007-09-27 13:01:25 +02001542 if (rw & WRITE) {
1543 count_vm_events(PGPGOUT, count);
1544 } else {
1545 task_io_account_read(bio->bi_size);
1546 count_vm_events(PGPGIN, count);
1547 }
1548
1549 if (unlikely(block_dump)) {
1550 char b[BDEVNAME_SIZE];
1551 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07001552 current->comm, task_pid_nr(current),
Jens Axboebf2de6f2007-09-27 13:01:25 +02001553 (rw & WRITE) ? "WRITE" : "READ",
1554 (unsigned long long)bio->bi_sector,
Jens Axboe6728cb02008-01-31 13:03:55 +01001555 bdevname(bio->bi_bdev, b));
Jens Axboebf2de6f2007-09-27 13:01:25 +02001556 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557 }
1558
1559 generic_make_request(bio);
1560}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001561EXPORT_SYMBOL(submit_bio);
1562
Kiyoshi Ueda3bcddea2007-12-11 17:52:28 -05001563/**
Kiyoshi Ueda82124d62008-09-18 10:45:38 -04001564 * blk_rq_check_limits - Helper function to check a request for the queue limit
1565 * @q: the queue
1566 * @rq: the request being checked
1567 *
1568 * Description:
1569 * @rq may have been made based on weaker limitations of upper-level queues
1570 * in request stacking drivers, and it may violate the limitation of @q.
1571 * Since the block layer and the underlying device driver trust @rq
1572 * after it is inserted to @q, it should be checked against @q before
1573 * the insertion using this generic function.
1574 *
1575 * This function should also be useful for request stacking drivers
1576 * in some cases below, so export this fuction.
1577 * Request stacking drivers like request-based dm may change the queue
1578 * limits while requests are in the queue (e.g. dm's table swapping).
1579 * Such request stacking drivers should check those requests agaist
1580 * the new queue limits again when they dispatch those requests,
1581 * although such checkings are also done against the old queue limits
1582 * when submitting requests.
1583 */
1584int blk_rq_check_limits(struct request_queue *q, struct request *rq)
1585{
1586 if (rq->nr_sectors > q->max_sectors ||
1587 rq->data_len > q->max_hw_sectors << 9) {
1588 printk(KERN_ERR "%s: over max size limit.\n", __func__);
1589 return -EIO;
1590 }
1591
1592 /*
1593 * queue's settings related to segment counting like q->bounce_pfn
1594 * may differ from that of other stacking queues.
1595 * Recalculate it to check the request correctly on this queue's
1596 * limitation.
1597 */
1598 blk_recalc_rq_segments(rq);
1599 if (rq->nr_phys_segments > q->max_phys_segments ||
1600 rq->nr_phys_segments > q->max_hw_segments) {
1601 printk(KERN_ERR "%s: over max segments limit.\n", __func__);
1602 return -EIO;
1603 }
1604
1605 return 0;
1606}
1607EXPORT_SYMBOL_GPL(blk_rq_check_limits);
1608
1609/**
1610 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
1611 * @q: the queue to submit the request
1612 * @rq: the request being queued
1613 */
1614int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
1615{
1616 unsigned long flags;
1617
1618 if (blk_rq_check_limits(q, rq))
1619 return -EIO;
1620
1621#ifdef CONFIG_FAIL_MAKE_REQUEST
1622 if (rq->rq_disk && rq->rq_disk->part0.make_it_fail &&
1623 should_fail(&fail_make_request, blk_rq_bytes(rq)))
1624 return -EIO;
1625#endif
1626
1627 spin_lock_irqsave(q->queue_lock, flags);
1628
1629 /*
1630 * Submitting request must be dequeued before calling this function
1631 * because it will be linked to another request_queue
1632 */
1633 BUG_ON(blk_queued_rq(rq));
1634
1635 drive_stat_acct(rq, 1);
1636 __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0);
1637
1638 spin_unlock_irqrestore(q->queue_lock, flags);
1639
1640 return 0;
1641}
1642EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
1643
1644/**
Tejun Heo53a08802008-12-03 12:41:26 +01001645 * blkdev_dequeue_request - dequeue request and start timeout timer
1646 * @req: request to dequeue
1647 *
1648 * Dequeue @req and start timeout timer on it. This hands off the
1649 * request to the driver.
1650 *
1651 * Block internal functions which don't want to start timer should
1652 * call elv_dequeue_request().
1653 */
1654void blkdev_dequeue_request(struct request *req)
1655{
1656 elv_dequeue_request(req->q, req);
1657
1658 /*
1659 * We are now handing the request to the hardware, add the
1660 * timeout handler.
1661 */
1662 blk_add_timer(req);
1663}
1664EXPORT_SYMBOL(blkdev_dequeue_request);
1665
Jens Axboebc58ba92009-01-23 10:54:44 +01001666static void blk_account_io_completion(struct request *req, unsigned int bytes)
1667{
1668 struct gendisk *disk = req->rq_disk;
1669
Jens Axboefb8ec182009-02-02 08:42:32 +01001670 if (!disk || !blk_do_io_stat(disk->queue))
Jens Axboebc58ba92009-01-23 10:54:44 +01001671 return;
1672
1673 if (blk_fs_request(req)) {
1674 const int rw = rq_data_dir(req);
1675 struct hd_struct *part;
1676 int cpu;
1677
1678 cpu = part_stat_lock();
1679 part = disk_map_sector_rcu(req->rq_disk, req->sector);
1680 part_stat_add(cpu, part, sectors[rw], bytes >> 9);
1681 part_stat_unlock();
1682 }
1683}
1684
1685static void blk_account_io_done(struct request *req)
1686{
1687 struct gendisk *disk = req->rq_disk;
1688
Jens Axboefb8ec182009-02-02 08:42:32 +01001689 if (!disk || !blk_do_io_stat(disk->queue))
Jens Axboebc58ba92009-01-23 10:54:44 +01001690 return;
1691
1692 /*
1693 * Account IO completion. bar_rq isn't accounted as a normal
1694 * IO on queueing nor completion. Accounting the containing
1695 * request is enough.
1696 */
1697 if (blk_fs_request(req) && req != &req->q->bar_rq) {
1698 unsigned long duration = jiffies - req->start_time;
1699 const int rw = rq_data_dir(req);
1700 struct hd_struct *part;
1701 int cpu;
1702
1703 cpu = part_stat_lock();
1704 part = disk_map_sector_rcu(disk, req->sector);
1705
1706 part_stat_inc(cpu, part, ios[rw]);
1707 part_stat_add(cpu, part, ticks[rw], duration);
1708 part_round_stats(cpu, part);
1709 part_dec_in_flight(part);
1710
1711 part_stat_unlock();
1712 }
1713}
1714
Tejun Heo53a08802008-12-03 12:41:26 +01001715/**
Kiyoshi Ueda3bcddea2007-12-11 17:52:28 -05001716 * __end_that_request_first - end I/O on a request
1717 * @req: the request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02001718 * @error: %0 for success, < %0 for error
Kiyoshi Ueda3bcddea2007-12-11 17:52:28 -05001719 * @nr_bytes: number of bytes to complete
1720 *
1721 * Description:
1722 * Ends I/O on a number of bytes attached to @req, and sets it up
1723 * for the next range of segments (if any) in the cluster.
1724 *
1725 * Return:
Randy Dunlap710027a2008-08-19 20:13:11 +02001726 * %0 - we are done with this request, call end_that_request_last()
1727 * %1 - still buffers pending for this request
Kiyoshi Ueda3bcddea2007-12-11 17:52:28 -05001728 **/
Kiyoshi Ueda5450d3e2007-12-11 17:53:03 -05001729static int __end_that_request_first(struct request *req, int error,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730 int nr_bytes)
1731{
Kiyoshi Ueda5450d3e2007-12-11 17:53:03 -05001732 int total_bytes, bio_nbytes, next_idx = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001733 struct bio *bio;
1734
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +01001735 trace_block_rq_complete(req->q, req);
Jens Axboe2056a782006-03-23 20:00:26 +01001736
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737 /*
Randy Dunlap710027a2008-08-19 20:13:11 +02001738 * for a REQ_TYPE_BLOCK_PC request, we want to carry any eventual
Linus Torvalds1da177e2005-04-16 15:20:36 -07001739 * sense key with us all the way through
1740 */
1741 if (!blk_pc_request(req))
1742 req->errors = 0;
1743
Jens Axboe6728cb02008-01-31 13:03:55 +01001744 if (error && (blk_fs_request(req) && !(req->cmd_flags & REQ_QUIET))) {
1745 printk(KERN_ERR "end_request: I/O error, dev %s, sector %llu\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001746 req->rq_disk ? req->rq_disk->disk_name : "?",
1747 (unsigned long long)req->sector);
1748 }
1749
Jens Axboebc58ba92009-01-23 10:54:44 +01001750 blk_account_io_completion(req, nr_bytes);
Jens Axboed72d9042005-11-01 08:35:42 +01001751
Linus Torvalds1da177e2005-04-16 15:20:36 -07001752 total_bytes = bio_nbytes = 0;
1753 while ((bio = req->bio) != NULL) {
1754 int nbytes;
1755
1756 if (nr_bytes >= bio->bi_size) {
1757 req->bio = bio->bi_next;
1758 nbytes = bio->bi_size;
NeilBrown5bb23a62007-09-27 12:46:13 +02001759 req_bio_endio(req, bio, nbytes, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001760 next_idx = 0;
1761 bio_nbytes = 0;
1762 } else {
1763 int idx = bio->bi_idx + next_idx;
1764
1765 if (unlikely(bio->bi_idx >= bio->bi_vcnt)) {
1766 blk_dump_rq_flags(req, "__end_that");
Jens Axboe6728cb02008-01-31 13:03:55 +01001767 printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n",
Harvey Harrison24c03d42008-05-01 04:35:17 -07001768 __func__, bio->bi_idx, bio->bi_vcnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001769 break;
1770 }
1771
1772 nbytes = bio_iovec_idx(bio, idx)->bv_len;
1773 BIO_BUG_ON(nbytes > bio->bi_size);
1774
1775 /*
1776 * not a complete bvec done
1777 */
1778 if (unlikely(nbytes > nr_bytes)) {
1779 bio_nbytes += nr_bytes;
1780 total_bytes += nr_bytes;
1781 break;
1782 }
1783
1784 /*
1785 * advance to the next vector
1786 */
1787 next_idx++;
1788 bio_nbytes += nbytes;
1789 }
1790
1791 total_bytes += nbytes;
1792 nr_bytes -= nbytes;
1793
Jens Axboe6728cb02008-01-31 13:03:55 +01001794 bio = req->bio;
1795 if (bio) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796 /*
1797 * end more in this run, or just return 'not-done'
1798 */
1799 if (unlikely(nr_bytes <= 0))
1800 break;
1801 }
1802 }
1803
1804 /*
1805 * completely done
1806 */
1807 if (!req->bio)
1808 return 0;
1809
1810 /*
1811 * if the request wasn't completed, update state
1812 */
1813 if (bio_nbytes) {
NeilBrown5bb23a62007-09-27 12:46:13 +02001814 req_bio_endio(req, bio, bio_nbytes, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815 bio->bi_idx += next_idx;
1816 bio_iovec(bio)->bv_offset += nr_bytes;
1817 bio_iovec(bio)->bv_len -= nr_bytes;
1818 }
1819
1820 blk_recalc_rq_sectors(req, total_bytes >> 9);
1821 blk_recalc_rq_segments(req);
1822 return 1;
1823}
1824
Linus Torvalds1da177e2005-04-16 15:20:36 -07001825/*
1826 * queue lock must be held
1827 */
Kiyoshi Ueda5450d3e2007-12-11 17:53:03 -05001828static void end_that_request_last(struct request *req, int error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001829{
Kiyoshi Uedab8286232007-12-11 17:53:24 -05001830 if (blk_rq_tagged(req))
1831 blk_queue_end_tag(req->q, req);
1832
1833 if (blk_queued_rq(req))
Tejun Heo53a08802008-12-03 12:41:26 +01001834 elv_dequeue_request(req->q, req);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001835
1836 if (unlikely(laptop_mode) && blk_fs_request(req))
1837 laptop_io_completion();
1838
Mike Andersone78042e2008-10-30 02:16:20 -07001839 blk_delete_timer(req);
1840
Jens Axboebc58ba92009-01-23 10:54:44 +01001841 blk_account_io_done(req);
Kiyoshi Uedab8286232007-12-11 17:53:24 -05001842
Linus Torvalds1da177e2005-04-16 15:20:36 -07001843 if (req->end_io)
Tejun Heo8ffdc652006-01-06 09:49:03 +01001844 req->end_io(req, error);
Kiyoshi Uedab8286232007-12-11 17:53:24 -05001845 else {
1846 if (blk_bidi_rq(req))
1847 __blk_put_request(req->next_rq->q, req->next_rq);
1848
Linus Torvalds1da177e2005-04-16 15:20:36 -07001849 __blk_put_request(req->q, req);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001850 }
1851}
1852
Kiyoshi Ueda3b113132007-12-11 17:41:17 -05001853/**
1854 * blk_rq_bytes - Returns bytes left to complete in the entire request
Randy Dunlap5d87a052008-02-20 09:01:22 +01001855 * @rq: the request being processed
Kiyoshi Ueda3b113132007-12-11 17:41:17 -05001856 **/
1857unsigned int blk_rq_bytes(struct request *rq)
Jens Axboea0cd1282007-09-21 10:41:07 +02001858{
1859 if (blk_fs_request(rq))
1860 return rq->hard_nr_sectors << 9;
1861
1862 return rq->data_len;
1863}
Kiyoshi Ueda3b113132007-12-11 17:41:17 -05001864EXPORT_SYMBOL_GPL(blk_rq_bytes);
1865
1866/**
1867 * blk_rq_cur_bytes - Returns bytes left to complete in the current segment
Randy Dunlap5d87a052008-02-20 09:01:22 +01001868 * @rq: the request being processed
Kiyoshi Ueda3b113132007-12-11 17:41:17 -05001869 **/
1870unsigned int blk_rq_cur_bytes(struct request *rq)
1871{
1872 if (blk_fs_request(rq))
1873 return rq->current_nr_sectors << 9;
1874
1875 if (rq->bio)
1876 return rq->bio->bi_size;
1877
1878 return rq->data_len;
1879}
1880EXPORT_SYMBOL_GPL(blk_rq_cur_bytes);
Jens Axboea0cd1282007-09-21 10:41:07 +02001881
1882/**
Jens Axboea0cd1282007-09-21 10:41:07 +02001883 * end_request - end I/O on the current segment of the request
Randy Dunlap8f731f72007-10-18 23:39:28 -07001884 * @req: the request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02001885 * @uptodate: error value or %0/%1 uptodate flag
Jens Axboea0cd1282007-09-21 10:41:07 +02001886 *
1887 * Description:
1888 * Ends I/O on the current segment of a request. If that is the only
1889 * remaining segment, the request is also completed and freed.
1890 *
Randy Dunlap710027a2008-08-19 20:13:11 +02001891 * This is a remnant of how older block drivers handled I/O completions.
1892 * Modern drivers typically end I/O on the full request in one go, unless
Jens Axboea0cd1282007-09-21 10:41:07 +02001893 * they have a residual value to account for. For that case this function
1894 * isn't really useful, unless the residual just happens to be the
1895 * full current segment. In other words, don't use this function in new
Kiyoshi Uedad00e29f2008-10-01 10:14:46 -04001896 * code. Use blk_end_request() or __blk_end_request() to end a request.
Jens Axboea0cd1282007-09-21 10:41:07 +02001897 **/
1898void end_request(struct request *req, int uptodate)
1899{
Kiyoshi Uedad00e29f2008-10-01 10:14:46 -04001900 int error = 0;
1901
1902 if (uptodate <= 0)
1903 error = uptodate ? uptodate : -EIO;
1904
1905 __blk_end_request(req, error, req->hard_cur_sectors << 9);
Jens Axboea0cd1282007-09-21 10:41:07 +02001906}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001907EXPORT_SYMBOL(end_request);
1908
Kiyoshi Ueda32fab442008-09-18 10:45:09 -04001909static int end_that_request_data(struct request *rq, int error,
1910 unsigned int nr_bytes, unsigned int bidi_bytes)
1911{
1912 if (rq->bio) {
1913 if (__end_that_request_first(rq, error, nr_bytes))
1914 return 1;
1915
1916 /* Bidi request must be completed as a whole */
1917 if (blk_bidi_rq(rq) &&
1918 __end_that_request_first(rq->next_rq, error, bidi_bytes))
1919 return 1;
1920 }
1921
1922 return 0;
1923}
1924
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001925/**
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001926 * blk_end_io - Generic end_io function to complete a request.
1927 * @rq: the request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02001928 * @error: %0 for success, < %0 for error
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05001929 * @nr_bytes: number of bytes to complete @rq
1930 * @bidi_bytes: number of bytes to complete @rq->next_rq
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001931 * @drv_callback: function called between completion of bios in the request
1932 * and completion of the request.
Randy Dunlap710027a2008-08-19 20:13:11 +02001933 * If the callback returns non %0, this helper returns without
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001934 * completion of the request.
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001935 *
1936 * Description:
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05001937 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001938 * If @rq has leftover, sets it up for the next range of segments.
1939 *
1940 * Return:
Randy Dunlap710027a2008-08-19 20:13:11 +02001941 * %0 - we are done with this request
1942 * %1 - this request is not freed yet, it still has pending buffers.
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001943 **/
Jens Axboe22b13212008-01-31 12:36:19 +01001944static int blk_end_io(struct request *rq, int error, unsigned int nr_bytes,
1945 unsigned int bidi_bytes,
1946 int (drv_callback)(struct request *))
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001947{
1948 struct request_queue *q = rq->q;
1949 unsigned long flags = 0UL;
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001950
Kiyoshi Ueda32fab442008-09-18 10:45:09 -04001951 if (end_that_request_data(rq, error, nr_bytes, bidi_bytes))
1952 return 1;
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001953
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001954 /* Special feature for tricky drivers */
1955 if (drv_callback && drv_callback(rq))
1956 return 1;
1957
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001958 add_disk_randomness(rq->rq_disk);
1959
1960 spin_lock_irqsave(q->queue_lock, flags);
Kiyoshi Uedab8286232007-12-11 17:53:24 -05001961 end_that_request_last(rq, error);
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001962 spin_unlock_irqrestore(q->queue_lock, flags);
1963
1964 return 0;
1965}
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001966
1967/**
1968 * blk_end_request - Helper function for drivers to complete the request.
1969 * @rq: the request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02001970 * @error: %0 for success, < %0 for error
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001971 * @nr_bytes: number of bytes to complete
1972 *
1973 * Description:
1974 * Ends I/O on a number of bytes attached to @rq.
1975 * If @rq has leftover, sets it up for the next range of segments.
1976 *
1977 * Return:
Randy Dunlap710027a2008-08-19 20:13:11 +02001978 * %0 - we are done with this request
1979 * %1 - still buffers pending for this request
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001980 **/
Jens Axboe22b13212008-01-31 12:36:19 +01001981int blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001982{
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05001983 return blk_end_io(rq, error, nr_bytes, 0, NULL);
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001984}
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001985EXPORT_SYMBOL_GPL(blk_end_request);
1986
1987/**
1988 * __blk_end_request - Helper function for drivers to complete the request.
1989 * @rq: the request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02001990 * @error: %0 for success, < %0 for error
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001991 * @nr_bytes: number of bytes to complete
1992 *
1993 * Description:
1994 * Must be called with queue lock held unlike blk_end_request().
1995 *
1996 * Return:
Randy Dunlap710027a2008-08-19 20:13:11 +02001997 * %0 - we are done with this request
1998 * %1 - still buffers pending for this request
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001999 **/
Jens Axboe22b13212008-01-31 12:36:19 +01002000int __blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002001{
Jens Axboe60540162008-08-26 13:34:34 +02002002 if (rq->bio && __end_that_request_first(rq, error, nr_bytes))
Jens Axboe051cc392008-08-08 11:06:45 +02002003 return 1;
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002004
2005 add_disk_randomness(rq->rq_disk);
2006
Kiyoshi Uedab8286232007-12-11 17:53:24 -05002007 end_that_request_last(rq, error);
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002008
2009 return 0;
2010}
2011EXPORT_SYMBOL_GPL(__blk_end_request);
2012
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002013/**
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05002014 * blk_end_bidi_request - Helper function for drivers to complete bidi request.
2015 * @rq: the bidi request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02002016 * @error: %0 for success, < %0 for error
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05002017 * @nr_bytes: number of bytes to complete @rq
2018 * @bidi_bytes: number of bytes to complete @rq->next_rq
2019 *
2020 * Description:
2021 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2022 *
2023 * Return:
Randy Dunlap710027a2008-08-19 20:13:11 +02002024 * %0 - we are done with this request
2025 * %1 - still buffers pending for this request
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05002026 **/
Jens Axboe22b13212008-01-31 12:36:19 +01002027int blk_end_bidi_request(struct request *rq, int error, unsigned int nr_bytes,
2028 unsigned int bidi_bytes)
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05002029{
2030 return blk_end_io(rq, error, nr_bytes, bidi_bytes, NULL);
2031}
2032EXPORT_SYMBOL_GPL(blk_end_bidi_request);
2033
2034/**
Kiyoshi Ueda32fab442008-09-18 10:45:09 -04002035 * blk_update_request - Special helper function for request stacking drivers
2036 * @rq: the request being processed
2037 * @error: %0 for success, < %0 for error
2038 * @nr_bytes: number of bytes to complete @rq
2039 *
2040 * Description:
2041 * Ends I/O on a number of bytes attached to @rq, but doesn't complete
2042 * the request structure even if @rq doesn't have leftover.
2043 * If @rq has leftover, sets it up for the next range of segments.
2044 *
2045 * This special helper function is only for request stacking drivers
2046 * (e.g. request-based dm) so that they can handle partial completion.
2047 * Actual device drivers should use blk_end_request instead.
2048 */
2049void blk_update_request(struct request *rq, int error, unsigned int nr_bytes)
2050{
2051 if (!end_that_request_data(rq, error, nr_bytes, 0)) {
2052 /*
2053 * These members are not updated in end_that_request_data()
2054 * when all bios are completed.
2055 * Update them so that the request stacking driver can find
2056 * how many bytes remain in the request later.
2057 */
2058 rq->nr_sectors = rq->hard_nr_sectors = 0;
2059 rq->current_nr_sectors = rq->hard_cur_sectors = 0;
2060 }
2061}
2062EXPORT_SYMBOL_GPL(blk_update_request);
2063
2064/**
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002065 * blk_end_request_callback - Special helper function for tricky drivers
2066 * @rq: the request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02002067 * @error: %0 for success, < %0 for error
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002068 * @nr_bytes: number of bytes to complete
2069 * @drv_callback: function called between completion of bios in the request
2070 * and completion of the request.
Randy Dunlap710027a2008-08-19 20:13:11 +02002071 * If the callback returns non %0, this helper returns without
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002072 * completion of the request.
2073 *
2074 * Description:
2075 * Ends I/O on a number of bytes attached to @rq.
2076 * If @rq has leftover, sets it up for the next range of segments.
2077 *
2078 * This special helper function is used only for existing tricky drivers.
2079 * (e.g. cdrom_newpc_intr() of ide-cd)
2080 * This interface will be removed when such drivers are rewritten.
2081 * Don't use this interface in other places anymore.
2082 *
2083 * Return:
Randy Dunlap710027a2008-08-19 20:13:11 +02002084 * %0 - we are done with this request
2085 * %1 - this request is not freed yet.
2086 * this request still has pending buffers or
2087 * the driver doesn't want to finish this request yet.
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002088 **/
Jens Axboe22b13212008-01-31 12:36:19 +01002089int blk_end_request_callback(struct request *rq, int error,
2090 unsigned int nr_bytes,
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002091 int (drv_callback)(struct request *))
2092{
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05002093 return blk_end_io(rq, error, nr_bytes, 0, drv_callback);
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002094}
2095EXPORT_SYMBOL_GPL(blk_end_request_callback);
2096
Jens Axboe86db1e22008-01-29 14:53:40 +01002097void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
2098 struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002099{
David Woodhoused628eae2008-08-09 16:22:17 +01002100 /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw, and
2101 we want BIO_RW_AHEAD (bit 1) to imply REQ_FAILFAST (bit 1). */
Jens Axboe4aff5e22006-08-10 08:44:47 +02002102 rq->cmd_flags |= (bio->bi_rw & 3);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002103
David Woodhousefb2dce82008-08-05 18:01:53 +01002104 if (bio_has_data(bio)) {
2105 rq->nr_phys_segments = bio_phys_segments(q, bio);
David Woodhousefb2dce82008-08-05 18:01:53 +01002106 rq->buffer = bio_data(bio);
2107 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002108 rq->current_nr_sectors = bio_cur_sectors(bio);
2109 rq->hard_cur_sectors = rq->current_nr_sectors;
2110 rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio);
Mike Christie0e75f902006-12-01 10:40:55 +01002111 rq->data_len = bio->bi_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002112
2113 rq->bio = rq->biotail = bio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002114
NeilBrown66846572007-08-16 13:31:28 +02002115 if (bio->bi_bdev)
2116 rq->rq_disk = bio->bi_bdev->bd_disk;
2117}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002118
Kiyoshi Uedaef9e3fa2008-10-01 16:12:15 +02002119/**
2120 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
2121 * @q : the queue of the device being checked
2122 *
2123 * Description:
2124 * Check if underlying low-level drivers of a device are busy.
2125 * If the drivers want to export their busy state, they must set own
2126 * exporting function using blk_queue_lld_busy() first.
2127 *
2128 * Basically, this function is used only by request stacking drivers
2129 * to stop dispatching requests to underlying devices when underlying
2130 * devices are busy. This behavior helps more I/O merging on the queue
2131 * of the request stacking driver and prevents I/O throughput regression
2132 * on burst I/O load.
2133 *
2134 * Return:
2135 * 0 - Not busy (The request stacking driver should dispatch request)
2136 * 1 - Busy (The request stacking driver should stop dispatching request)
2137 */
2138int blk_lld_busy(struct request_queue *q)
2139{
2140 if (q->lld_busy_fn)
2141 return q->lld_busy_fn(q);
2142
2143 return 0;
2144}
2145EXPORT_SYMBOL_GPL(blk_lld_busy);
2146
Jens Axboe18887ad2008-07-28 13:08:45 +02002147int kblockd_schedule_work(struct request_queue *q, struct work_struct *work)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002148{
2149 return queue_work(kblockd_workqueue, work);
2150}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002151EXPORT_SYMBOL(kblockd_schedule_work);
2152
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153int __init blk_dev_init(void)
2154{
2155 kblockd_workqueue = create_workqueue("kblockd");
2156 if (!kblockd_workqueue)
2157 panic("Failed to create kblockd\n");
2158
2159 request_cachep = kmem_cache_create("blkdev_requests",
Paul Mundt20c2df82007-07-20 10:11:58 +09002160 sizeof(struct request), 0, SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002161
Jens Axboe8324aa92008-01-29 14:51:59 +01002162 blk_requestq_cachep = kmem_cache_create("blkdev_queue",
Jens Axboe165125e2007-07-24 09:28:11 +02002163 sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002164
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165 return 0;
2166}
2167