blob: fa212348c4c96df59b41325259d2215eed12abd6 [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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
Jens Axboe8324aa92008-01-29 14:51:59 +010032#include "blk.h"
33
Jens Axboe165125e2007-07-24 09:28:11 +020034static int __make_request(struct request_queue *q, struct bio *bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -070035
36/*
37 * For the allocated request tables
38 */
Adrian Bunk5ece6c52008-02-18 13:45:51 +010039static struct kmem_cache *request_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070040
41/*
42 * For queue allocation
43 */
Jens Axboe6728cb02008-01-31 13:03:55 +010044struct kmem_cache *blk_requestq_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070045
46/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070047 * Controlling structure to kblockd
48 */
Jens Axboeff856ba2006-01-09 16:02:34 +010049static struct workqueue_struct *kblockd_workqueue;
Linus Torvalds1da177e2005-04-16 15:20:36 -070050
Jens Axboe26b82562008-01-29 13:54:41 +010051static void drive_stat_acct(struct request *rq, int new_io)
52{
Jens Axboe28f13702008-05-07 10:15:46 +020053 struct hd_struct *part;
Jens Axboe26b82562008-01-29 13:54:41 +010054 int rw = rq_data_dir(rq);
Tejun Heoc9959052008-08-25 19:47:21 +090055 int cpu;
Jens Axboe26b82562008-01-29 13:54:41 +010056
57 if (!blk_fs_request(rq) || !rq->rq_disk)
58 return;
59
Tejun Heo074a7ac2008-08-25 19:56:14 +090060 cpu = part_stat_lock();
Tejun Heoe71bf0d2008-09-03 09:03:02 +020061 part = disk_map_sector_rcu(rq->rq_disk, rq->sector);
Tejun Heoc9959052008-08-25 19:47:21 +090062
Jens Axboe28f13702008-05-07 10:15:46 +020063 if (!new_io)
Tejun Heo074a7ac2008-08-25 19:56:14 +090064 part_stat_inc(cpu, part, merges[rw]);
Jens Axboe28f13702008-05-07 10:15:46 +020065 else {
Tejun Heo074a7ac2008-08-25 19:56:14 +090066 part_round_stats(cpu, part);
67 part_inc_in_flight(part);
Jens Axboe26b82562008-01-29 13:54:41 +010068 }
Tejun Heoe71bf0d2008-09-03 09:03:02 +020069
Tejun Heo074a7ac2008-08-25 19:56:14 +090070 part_stat_unlock();
Jens Axboe26b82562008-01-29 13:54:41 +010071}
72
Jens Axboe8324aa92008-01-29 14:51:59 +010073void blk_queue_congestion_threshold(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -070074{
75 int nr;
76
77 nr = q->nr_requests - (q->nr_requests / 8) + 1;
78 if (nr > q->nr_requests)
79 nr = q->nr_requests;
80 q->nr_congestion_on = nr;
81
82 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
83 if (nr < 1)
84 nr = 1;
85 q->nr_congestion_off = nr;
86}
87
Linus Torvalds1da177e2005-04-16 15:20:36 -070088/**
89 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
90 * @bdev: device
91 *
92 * Locates the passed device's request queue and returns the address of its
93 * backing_dev_info
94 *
95 * Will return NULL if the request queue cannot be located.
96 */
97struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
98{
99 struct backing_dev_info *ret = NULL;
Jens Axboe165125e2007-07-24 09:28:11 +0200100 struct request_queue *q = bdev_get_queue(bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101
102 if (q)
103 ret = &q->backing_dev_info;
104 return ret;
105}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106EXPORT_SYMBOL(blk_get_backing_dev_info);
107
FUJITA Tomonori2a4aa302008-04-29 09:54:36 +0200108void blk_rq_init(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109{
FUJITA Tomonori1afb20f2008-04-25 12:26:28 +0200110 memset(rq, 0, sizeof(*rq));
111
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 INIT_LIST_HEAD(&rq->queuelist);
Jens Axboe242f9dc2008-09-14 05:55:09 -0700113 INIT_LIST_HEAD(&rq->timeout_list);
Jens Axboec7c22e42008-09-13 20:26:01 +0200114 rq->cpu = -1;
Jens Axboe63a71382008-02-08 12:41:03 +0100115 rq->q = q;
116 rq->sector = rq->hard_sector = (sector_t) -1;
Jens Axboe2e662b62006-07-13 11:55:04 +0200117 INIT_HLIST_NODE(&rq->hash);
118 RB_CLEAR_NODE(&rq->rb_node);
FUJITA Tomonorid7e3c322008-04-29 09:54:39 +0200119 rq->cmd = rq->__cmd;
Jens Axboe63a71382008-02-08 12:41:03 +0100120 rq->tag = -1;
Jens Axboe63a71382008-02-08 12:41:03 +0100121 rq->ref_count = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122}
FUJITA Tomonori2a4aa302008-04-29 09:54:36 +0200123EXPORT_SYMBOL(blk_rq_init);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124
NeilBrown5bb23a62007-09-27 12:46:13 +0200125static void req_bio_endio(struct request *rq, struct bio *bio,
126 unsigned int nbytes, int error)
Tejun Heo797e7db2006-01-06 09:51:03 +0100127{
Jens Axboe165125e2007-07-24 09:28:11 +0200128 struct request_queue *q = rq->q;
Tejun Heo797e7db2006-01-06 09:51:03 +0100129
NeilBrown5bb23a62007-09-27 12:46:13 +0200130 if (&q->bar_rq != rq) {
131 if (error)
132 clear_bit(BIO_UPTODATE, &bio->bi_flags);
133 else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
134 error = -EIO;
Tejun Heo797e7db2006-01-06 09:51:03 +0100135
NeilBrown5bb23a62007-09-27 12:46:13 +0200136 if (unlikely(nbytes > bio->bi_size)) {
Jens Axboe6728cb02008-01-31 13:03:55 +0100137 printk(KERN_ERR "%s: want %u bytes done, %u left\n",
Harvey Harrison24c03d42008-05-01 04:35:17 -0700138 __func__, nbytes, bio->bi_size);
NeilBrown5bb23a62007-09-27 12:46:13 +0200139 nbytes = bio->bi_size;
140 }
Tejun Heo797e7db2006-01-06 09:51:03 +0100141
NeilBrown5bb23a62007-09-27 12:46:13 +0200142 bio->bi_size -= nbytes;
143 bio->bi_sector += (nbytes >> 9);
Martin K. Petersen7ba1ba12008-06-30 20:04:41 +0200144
145 if (bio_integrity(bio))
146 bio_integrity_advance(bio, nbytes);
147
NeilBrown5bb23a62007-09-27 12:46:13 +0200148 if (bio->bi_size == 0)
NeilBrown6712ecf2007-09-27 12:47:43 +0200149 bio_endio(bio, error);
NeilBrown5bb23a62007-09-27 12:46:13 +0200150 } else {
151
152 /*
153 * Okay, this is the barrier request in progress, just
154 * record the error;
155 */
156 if (error && !q->orderr)
157 q->orderr = error;
158 }
Tejun Heo797e7db2006-01-06 09:51:03 +0100159}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161void blk_dump_rq_flags(struct request *rq, char *msg)
162{
163 int bit;
164
Jens Axboe6728cb02008-01-31 13:03:55 +0100165 printk(KERN_INFO "%s: dev %s: type=%x, flags=%x\n", msg,
Jens Axboe4aff5e22006-08-10 08:44:47 +0200166 rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type,
167 rq->cmd_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168
Jens Axboe6728cb02008-01-31 13:03:55 +0100169 printk(KERN_INFO " sector %llu, nr/cnr %lu/%u\n",
170 (unsigned long long)rq->sector,
171 rq->nr_sectors,
172 rq->current_nr_sectors);
173 printk(KERN_INFO " bio %p, biotail %p, buffer %p, data %p, len %u\n",
174 rq->bio, rq->biotail,
175 rq->buffer, rq->data,
176 rq->data_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177
Jens Axboe4aff5e22006-08-10 08:44:47 +0200178 if (blk_pc_request(rq)) {
Jens Axboe6728cb02008-01-31 13:03:55 +0100179 printk(KERN_INFO " cdb: ");
FUJITA Tomonorid34c87e2008-04-29 14:37:52 +0200180 for (bit = 0; bit < BLK_MAX_CDB; bit++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 printk("%02x ", rq->cmd[bit]);
182 printk("\n");
183 }
184}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185EXPORT_SYMBOL(blk_dump_rq_flags);
186
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187/*
188 * "plug" the device if there are no outstanding requests: this will
189 * force the transfer to start only after we have put all the requests
190 * on the list.
191 *
192 * This is called with interrupts off and no requests on the queue and
193 * with the queue lock held.
194 */
Jens Axboe165125e2007-07-24 09:28:11 +0200195void blk_plug_device(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196{
197 WARN_ON(!irqs_disabled());
198
199 /*
200 * don't plug a stopped queue, it must be paired with blk_start_queue()
201 * which will restart the queueing
202 */
Coywolf Qi Hunt7daac492006-04-19 10:14:49 +0200203 if (blk_queue_stopped(q))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204 return;
205
Jens Axboee48ec692008-07-03 13:18:54 +0200206 if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED, q)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207 mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
Jens Axboe2056a782006-03-23 20:00:26 +0100208 blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG);
209 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211EXPORT_SYMBOL(blk_plug_device);
212
Jens Axboe6c5e0c42008-08-01 20:31:32 +0200213/**
214 * blk_plug_device_unlocked - plug a device without queue lock held
215 * @q: The &struct request_queue to plug
216 *
217 * Description:
218 * Like @blk_plug_device(), but grabs the queue lock and disables
219 * interrupts.
220 **/
221void blk_plug_device_unlocked(struct request_queue *q)
222{
223 unsigned long flags;
224
225 spin_lock_irqsave(q->queue_lock, flags);
226 blk_plug_device(q);
227 spin_unlock_irqrestore(q->queue_lock, flags);
228}
229EXPORT_SYMBOL(blk_plug_device_unlocked);
230
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231/*
232 * remove the queue from the plugged list, if present. called with
233 * queue lock held and interrupts disabled.
234 */
Jens Axboe165125e2007-07-24 09:28:11 +0200235int blk_remove_plug(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236{
237 WARN_ON(!irqs_disabled());
238
Jens Axboee48ec692008-07-03 13:18:54 +0200239 if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED, q))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 return 0;
241
242 del_timer(&q->unplug_timer);
243 return 1;
244}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245EXPORT_SYMBOL(blk_remove_plug);
246
247/*
248 * remove the plug and let it rip..
249 */
Jens Axboe165125e2007-07-24 09:28:11 +0200250void __generic_unplug_device(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251{
Coywolf Qi Hunt7daac492006-04-19 10:14:49 +0200252 if (unlikely(blk_queue_stopped(q)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253 return;
254
255 if (!blk_remove_plug(q))
256 return;
257
Jens Axboe22e2c502005-06-27 10:55:12 +0200258 q->request_fn(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259}
260EXPORT_SYMBOL(__generic_unplug_device);
261
262/**
263 * generic_unplug_device - fire a request queue
Jens Axboe165125e2007-07-24 09:28:11 +0200264 * @q: The &struct request_queue in question
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 *
266 * Description:
267 * Linux uses plugging to build bigger requests queues before letting
268 * the device have at them. If a queue is plugged, the I/O scheduler
269 * is still adding and merging requests on the queue. Once the queue
270 * gets unplugged, the request_fn defined for the queue is invoked and
271 * transfers started.
272 **/
Jens Axboe165125e2007-07-24 09:28:11 +0200273void generic_unplug_device(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274{
Jens Axboedbaf2c02008-05-07 09:48:17 +0200275 if (blk_queue_plugged(q)) {
276 spin_lock_irq(q->queue_lock);
277 __generic_unplug_device(q);
278 spin_unlock_irq(q->queue_lock);
279 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280}
281EXPORT_SYMBOL(generic_unplug_device);
282
283static void blk_backing_dev_unplug(struct backing_dev_info *bdi,
284 struct page *page)
285{
Jens Axboe165125e2007-07-24 09:28:11 +0200286 struct request_queue *q = bdi->unplug_io_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287
Alan D. Brunelle2ad8b1e2007-11-07 14:26:56 -0500288 blk_unplug(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289}
290
Jens Axboe86db1e22008-01-29 14:53:40 +0100291void blk_unplug_work(struct work_struct *work)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292{
Jens Axboe165125e2007-07-24 09:28:11 +0200293 struct request_queue *q =
294 container_of(work, struct request_queue, unplug_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295
Jens Axboe2056a782006-03-23 20:00:26 +0100296 blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
297 q->rq.count[READ] + q->rq.count[WRITE]);
298
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 q->unplug_fn(q);
300}
301
Jens Axboe86db1e22008-01-29 14:53:40 +0100302void blk_unplug_timeout(unsigned long data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303{
Jens Axboe165125e2007-07-24 09:28:11 +0200304 struct request_queue *q = (struct request_queue *)data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305
Jens Axboe2056a782006-03-23 20:00:26 +0100306 blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_TIMER, NULL,
307 q->rq.count[READ] + q->rq.count[WRITE]);
308
Jens Axboe18887ad2008-07-28 13:08:45 +0200309 kblockd_schedule_work(q, &q->unplug_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310}
311
Alan D. Brunelle2ad8b1e2007-11-07 14:26:56 -0500312void blk_unplug(struct request_queue *q)
313{
314 /*
315 * devices don't necessarily have an ->unplug_fn defined
316 */
317 if (q->unplug_fn) {
318 blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
319 q->rq.count[READ] + q->rq.count[WRITE]);
320
321 q->unplug_fn(q);
322 }
323}
324EXPORT_SYMBOL(blk_unplug);
325
Jens Axboec7c22e42008-09-13 20:26:01 +0200326static void blk_invoke_request_fn(struct request_queue *q)
327{
328 /*
329 * one level of recursion is ok and is much faster than kicking
330 * the unplug handling
331 */
332 if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
333 q->request_fn(q);
334 queue_flag_clear(QUEUE_FLAG_REENTER, q);
335 } else {
336 queue_flag_set(QUEUE_FLAG_PLUGGED, q);
337 kblockd_schedule_work(q, &q->unplug_work);
338 }
339}
340
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341/**
342 * blk_start_queue - restart a previously stopped queue
Jens Axboe165125e2007-07-24 09:28:11 +0200343 * @q: The &struct request_queue in question
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 *
345 * Description:
346 * blk_start_queue() will clear the stop flag on the queue, and call
347 * the request_fn for the queue if it was in a stopped state when
348 * entered. Also see blk_stop_queue(). Queue lock must be held.
349 **/
Jens Axboe165125e2007-07-24 09:28:11 +0200350void blk_start_queue(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351{
Paolo 'Blaisorblade' Giarrussoa038e252006-06-05 12:09:01 +0200352 WARN_ON(!irqs_disabled());
353
Nick Piggin75ad23b2008-04-29 14:48:33 +0200354 queue_flag_clear(QUEUE_FLAG_STOPPED, q);
Jens Axboec7c22e42008-09-13 20:26:01 +0200355 blk_invoke_request_fn(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357EXPORT_SYMBOL(blk_start_queue);
358
359/**
360 * blk_stop_queue - stop a queue
Jens Axboe165125e2007-07-24 09:28:11 +0200361 * @q: The &struct request_queue in question
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 *
363 * Description:
364 * The Linux block layer assumes that a block driver will consume all
365 * entries on the request queue when the request_fn strategy is called.
366 * Often this will not happen, because of hardware limitations (queue
367 * depth settings). If a device driver gets a 'queue full' response,
368 * or if it simply chooses not to queue more I/O at one point, it can
369 * call this function to prevent the request_fn from being called until
370 * the driver has signalled it's ready to go again. This happens by calling
371 * blk_start_queue() to restart queue operations. Queue lock must be held.
372 **/
Jens Axboe165125e2007-07-24 09:28:11 +0200373void blk_stop_queue(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374{
375 blk_remove_plug(q);
Nick Piggin75ad23b2008-04-29 14:48:33 +0200376 queue_flag_set(QUEUE_FLAG_STOPPED, q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377}
378EXPORT_SYMBOL(blk_stop_queue);
379
380/**
381 * blk_sync_queue - cancel any pending callbacks on a queue
382 * @q: the queue
383 *
384 * Description:
385 * The block layer may perform asynchronous callback activity
386 * on a queue, such as calling the unplug function after a timeout.
387 * A block device may call blk_sync_queue to ensure that any
388 * such activity is cancelled, thus allowing it to release resources
Michael Opdenacker59c51592007-05-09 08:57:56 +0200389 * that the callbacks might use. The caller must already have made sure
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390 * that its ->make_request_fn will not re-add plugging prior to calling
391 * this function.
392 *
393 */
394void blk_sync_queue(struct request_queue *q)
395{
396 del_timer_sync(&q->unplug_timer);
Oleg Nesterovabbeb882007-10-23 15:08:19 +0200397 kblockd_flush_work(&q->unplug_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398}
399EXPORT_SYMBOL(blk_sync_queue);
400
401/**
402 * blk_run_queue - run a single device queue
403 * @q: The queue to run
404 */
Nick Piggin75ad23b2008-04-29 14:48:33 +0200405void __blk_run_queue(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407 blk_remove_plug(q);
Jens Axboedac07ec2006-05-11 08:20:16 +0200408
409 /*
410 * Only recurse once to avoid overrunning the stack, let the unplug
411 * handling reinvoke the handler shortly if we already got there.
412 */
Jens Axboec7c22e42008-09-13 20:26:01 +0200413 if (!elv_queue_empty(q))
414 blk_invoke_request_fn(q);
Nick Piggin75ad23b2008-04-29 14:48:33 +0200415}
416EXPORT_SYMBOL(__blk_run_queue);
Jens Axboedac07ec2006-05-11 08:20:16 +0200417
Nick Piggin75ad23b2008-04-29 14:48:33 +0200418/**
419 * blk_run_queue - run a single device queue
420 * @q: The queue to run
421 */
422void blk_run_queue(struct request_queue *q)
423{
424 unsigned long flags;
425
426 spin_lock_irqsave(q->queue_lock, flags);
427 __blk_run_queue(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 spin_unlock_irqrestore(q->queue_lock, flags);
429}
430EXPORT_SYMBOL(blk_run_queue);
431
Jens Axboe165125e2007-07-24 09:28:11 +0200432void blk_put_queue(struct request_queue *q)
Al Viro483f4af2006-03-18 18:34:37 -0500433{
434 kobject_put(&q->kobj);
435}
Al Viro483f4af2006-03-18 18:34:37 -0500436
Jens Axboe6728cb02008-01-31 13:03:55 +0100437void blk_cleanup_queue(struct request_queue *q)
Al Viro483f4af2006-03-18 18:34:37 -0500438{
Jens Axboee3335de2008-09-18 09:22:54 -0700439 /*
440 * We know we have process context here, so we can be a little
441 * cautious and ensure that pending block actions on this device
442 * are done before moving on. Going into this function, we should
443 * not have processes doing IO to this device.
444 */
445 blk_sync_queue(q);
446
Al Viro483f4af2006-03-18 18:34:37 -0500447 mutex_lock(&q->sysfs_lock);
Nick Piggin75ad23b2008-04-29 14:48:33 +0200448 queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q);
Al Viro483f4af2006-03-18 18:34:37 -0500449 mutex_unlock(&q->sysfs_lock);
450
451 if (q->elevator)
452 elevator_exit(q->elevator);
453
454 blk_put_queue(q);
455}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456EXPORT_SYMBOL(blk_cleanup_queue);
457
Jens Axboe165125e2007-07-24 09:28:11 +0200458static int blk_init_free_list(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459{
460 struct request_list *rl = &q->rq;
461
462 rl->count[READ] = rl->count[WRITE] = 0;
463 rl->starved[READ] = rl->starved[WRITE] = 0;
Tejun Heocb98fc82005-10-28 08:29:39 +0200464 rl->elvpriv = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465 init_waitqueue_head(&rl->wait[READ]);
466 init_waitqueue_head(&rl->wait[WRITE]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467
Christoph Lameter19460892005-06-23 00:08:19 -0700468 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
469 mempool_free_slab, request_cachep, q->node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470
471 if (!rl->rq_pool)
472 return -ENOMEM;
473
474 return 0;
475}
476
Jens Axboe165125e2007-07-24 09:28:11 +0200477struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478{
Christoph Lameter19460892005-06-23 00:08:19 -0700479 return blk_alloc_queue_node(gfp_mask, -1);
480}
481EXPORT_SYMBOL(blk_alloc_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482
Jens Axboe165125e2007-07-24 09:28:11 +0200483struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
Christoph Lameter19460892005-06-23 00:08:19 -0700484{
Jens Axboe165125e2007-07-24 09:28:11 +0200485 struct request_queue *q;
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700486 int err;
Christoph Lameter19460892005-06-23 00:08:19 -0700487
Jens Axboe8324aa92008-01-29 14:51:59 +0100488 q = kmem_cache_alloc_node(blk_requestq_cachep,
Christoph Lameter94f60302007-07-17 04:03:29 -0700489 gfp_mask | __GFP_ZERO, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490 if (!q)
491 return NULL;
492
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700493 q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug;
494 q->backing_dev_info.unplug_io_data = q;
495 err = bdi_init(&q->backing_dev_info);
496 if (err) {
Jens Axboe8324aa92008-01-29 14:51:59 +0100497 kmem_cache_free(blk_requestq_cachep, q);
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700498 return NULL;
499 }
500
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501 init_timer(&q->unplug_timer);
Jens Axboe242f9dc2008-09-14 05:55:09 -0700502 setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
503 INIT_LIST_HEAD(&q->timeout_list);
Al Viro483f4af2006-03-18 18:34:37 -0500504
Jens Axboe8324aa92008-01-29 14:51:59 +0100505 kobject_init(&q->kobj, &blk_queue_ktype);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506
Al Viro483f4af2006-03-18 18:34:37 -0500507 mutex_init(&q->sysfs_lock);
Neil Browne7e72bf2008-05-14 16:05:54 -0700508 spin_lock_init(&q->__queue_lock);
Al Viro483f4af2006-03-18 18:34:37 -0500509
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510 return q;
511}
Christoph Lameter19460892005-06-23 00:08:19 -0700512EXPORT_SYMBOL(blk_alloc_queue_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513
514/**
515 * blk_init_queue - prepare a request queue for use with a block device
516 * @rfn: The function to be called to process requests that have been
517 * placed on the queue.
518 * @lock: Request queue spin lock
519 *
520 * Description:
521 * If a block device wishes to use the standard request handling procedures,
522 * which sorts requests and coalesces adjacent requests, then it must
523 * call blk_init_queue(). The function @rfn will be called when there
524 * are requests on the queue that need to be processed. If the device
525 * supports plugging, then @rfn may not be called immediately when requests
526 * are available on the queue, but may be called at some time later instead.
527 * Plugged queues are generally unplugged when a buffer belonging to one
528 * of the requests on the queue is needed, or due to memory pressure.
529 *
530 * @rfn is not required, or even expected, to remove all requests off the
531 * queue, but only as many as it can handle at a time. If it does leave
532 * requests on the queue, it is responsible for arranging that the requests
533 * get dealt with eventually.
534 *
535 * The queue spin lock must be held while manipulating the requests on the
Paolo 'Blaisorblade' Giarrussoa038e252006-06-05 12:09:01 +0200536 * request queue; this lock will be taken also from interrupt context, so irq
537 * disabling is needed for it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538 *
Randy Dunlap710027a2008-08-19 20:13:11 +0200539 * Function returns a pointer to the initialized request queue, or %NULL if
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540 * it didn't succeed.
541 *
542 * Note:
543 * blk_init_queue() must be paired with a blk_cleanup_queue() call
544 * when the block device is deactivated (such as at module unload).
545 **/
Christoph Lameter19460892005-06-23 00:08:19 -0700546
Jens Axboe165125e2007-07-24 09:28:11 +0200547struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548{
Christoph Lameter19460892005-06-23 00:08:19 -0700549 return blk_init_queue_node(rfn, lock, -1);
550}
551EXPORT_SYMBOL(blk_init_queue);
552
Jens Axboe165125e2007-07-24 09:28:11 +0200553struct request_queue *
Christoph Lameter19460892005-06-23 00:08:19 -0700554blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
555{
Jens Axboe165125e2007-07-24 09:28:11 +0200556 struct request_queue *q = blk_alloc_queue_node(GFP_KERNEL, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557
558 if (!q)
559 return NULL;
560
Christoph Lameter19460892005-06-23 00:08:19 -0700561 q->node = node_id;
Al Viro8669aaf2006-03-18 13:50:00 -0500562 if (blk_init_free_list(q)) {
Jens Axboe8324aa92008-01-29 14:51:59 +0100563 kmem_cache_free(blk_requestq_cachep, q);
Al Viro8669aaf2006-03-18 13:50:00 -0500564 return NULL;
565 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566
152587d2005-04-12 16:22:06 -0500567 /*
568 * if caller didn't supply a lock, they get per-queue locking with
569 * our embedded lock
570 */
Neil Browne7e72bf2008-05-14 16:05:54 -0700571 if (!lock)
152587d2005-04-12 16:22:06 -0500572 lock = &q->__queue_lock;
152587d2005-04-12 16:22:06 -0500573
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 q->request_fn = rfn;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575 q->prep_rq_fn = NULL;
576 q->unplug_fn = generic_unplug_device;
Kiyoshi Ueda4ee5eaf2008-09-18 10:46:13 -0400577 q->queue_flags = (1 << QUEUE_FLAG_CLUSTER |
578 1 << QUEUE_FLAG_STACKABLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579 q->queue_lock = lock;
580
581 blk_queue_segment_boundary(q, 0xffffffff);
582
583 blk_queue_make_request(q, __make_request);
584 blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE);
585
586 blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
587 blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
588
Alan Stern44ec9542007-02-20 11:01:57 -0500589 q->sg_reserved_size = INT_MAX;
590
FUJITA Tomonoriabf54392008-08-16 14:10:05 +0900591 blk_set_cmd_filter_defaults(&q->cmd_filter);
592
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 /*
594 * all done
595 */
596 if (!elevator_init(q, NULL)) {
597 blk_queue_congestion_threshold(q);
598 return q;
599 }
600
Al Viro8669aaf2006-03-18 13:50:00 -0500601 blk_put_queue(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700602 return NULL;
603}
Christoph Lameter19460892005-06-23 00:08:19 -0700604EXPORT_SYMBOL(blk_init_queue_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605
Jens Axboe165125e2007-07-24 09:28:11 +0200606int blk_get_queue(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607{
Nick Pigginfde6ad22005-06-23 00:08:53 -0700608 if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
Al Viro483f4af2006-03-18 18:34:37 -0500609 kobject_get(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610 return 0;
611 }
612
613 return 1;
614}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615
Jens Axboe165125e2007-07-24 09:28:11 +0200616static inline void blk_free_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617{
Jens Axboe4aff5e22006-08-10 08:44:47 +0200618 if (rq->cmd_flags & REQ_ELVPRIV)
Tejun Heocb98fc82005-10-28 08:29:39 +0200619 elv_put_request(q, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620 mempool_free(rq, q->rq.rq_pool);
621}
622
Jens Axboe1ea25ec2006-07-18 22:24:11 +0200623static struct request *
Jens Axboe165125e2007-07-24 09:28:11 +0200624blk_alloc_request(struct request_queue *q, int rw, int priv, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625{
626 struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask);
627
628 if (!rq)
629 return NULL;
630
FUJITA Tomonori2a4aa302008-04-29 09:54:36 +0200631 blk_rq_init(q, rq);
FUJITA Tomonori1afb20f2008-04-25 12:26:28 +0200632
Jens Axboe49171e52006-08-10 08:59:11 +0200633 rq->cmd_flags = rw | REQ_ALLOCED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634
Tejun Heocb98fc82005-10-28 08:29:39 +0200635 if (priv) {
Jens Axboecb78b282006-07-28 09:32:57 +0200636 if (unlikely(elv_set_request(q, rq, gfp_mask))) {
Tejun Heocb98fc82005-10-28 08:29:39 +0200637 mempool_free(rq, q->rq.rq_pool);
638 return NULL;
639 }
Jens Axboe4aff5e22006-08-10 08:44:47 +0200640 rq->cmd_flags |= REQ_ELVPRIV;
Tejun Heocb98fc82005-10-28 08:29:39 +0200641 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642
Tejun Heocb98fc82005-10-28 08:29:39 +0200643 return rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644}
645
646/*
647 * ioc_batching returns true if the ioc is a valid batching request and
648 * should be given priority access to a request.
649 */
Jens Axboe165125e2007-07-24 09:28:11 +0200650static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651{
652 if (!ioc)
653 return 0;
654
655 /*
656 * Make sure the process is able to allocate at least 1 request
657 * even if the batch times out, otherwise we could theoretically
658 * lose wakeups.
659 */
660 return ioc->nr_batch_requests == q->nr_batching ||
661 (ioc->nr_batch_requests > 0
662 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
663}
664
665/*
666 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
667 * will cause the process to be a "batcher" on all queues in the system. This
668 * is the behaviour we want though - once it gets a wakeup it should be given
669 * a nice run.
670 */
Jens Axboe165125e2007-07-24 09:28:11 +0200671static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672{
673 if (!ioc || ioc_batching(q, ioc))
674 return;
675
676 ioc->nr_batch_requests = q->nr_batching;
677 ioc->last_waited = jiffies;
678}
679
Jens Axboe165125e2007-07-24 09:28:11 +0200680static void __freed_request(struct request_queue *q, int rw)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681{
682 struct request_list *rl = &q->rq;
683
684 if (rl->count[rw] < queue_congestion_off_threshold(q))
Thomas Maier79e2de42006-10-19 23:28:15 -0700685 blk_clear_queue_congested(q, rw);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686
687 if (rl->count[rw] + 1 <= q->nr_requests) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688 if (waitqueue_active(&rl->wait[rw]))
689 wake_up(&rl->wait[rw]);
690
691 blk_clear_queue_full(q, rw);
692 }
693}
694
695/*
696 * A request has just been released. Account for it, update the full and
697 * congestion status, wake up any waiters. Called under q->queue_lock.
698 */
Jens Axboe165125e2007-07-24 09:28:11 +0200699static void freed_request(struct request_queue *q, int rw, int priv)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700{
701 struct request_list *rl = &q->rq;
702
703 rl->count[rw]--;
Tejun Heocb98fc82005-10-28 08:29:39 +0200704 if (priv)
705 rl->elvpriv--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706
707 __freed_request(q, rw);
708
709 if (unlikely(rl->starved[rw ^ 1]))
710 __freed_request(q, rw ^ 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711}
712
713#define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist)
714/*
Nick Piggind6344532005-06-28 20:45:14 -0700715 * Get a free request, queue_lock must be held.
716 * Returns NULL on failure, with queue_lock held.
717 * Returns !NULL on success, with queue_lock *not held*.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 */
Jens Axboe165125e2007-07-24 09:28:11 +0200719static struct request *get_request(struct request_queue *q, int rw_flags,
Jens Axboe7749a8d2006-12-13 13:02:26 +0100720 struct bio *bio, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721{
722 struct request *rq = NULL;
723 struct request_list *rl = &q->rq;
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100724 struct io_context *ioc = NULL;
Jens Axboe7749a8d2006-12-13 13:02:26 +0100725 const int rw = rw_flags & 0x01;
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100726 int may_queue, priv;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727
Jens Axboe7749a8d2006-12-13 13:02:26 +0100728 may_queue = elv_may_queue(q, rw_flags);
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100729 if (may_queue == ELV_MQUEUE_NO)
730 goto rq_starved;
731
732 if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) {
733 if (rl->count[rw]+1 >= q->nr_requests) {
Jens Axboeb5deef92006-07-19 23:39:40 +0200734 ioc = current_io_context(GFP_ATOMIC, q->node);
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100735 /*
736 * The queue will fill after this allocation, so set
737 * it as full, and mark this process as "batching".
738 * This process will be allowed to complete a batch of
739 * requests, others will be blocked.
740 */
741 if (!blk_queue_full(q, rw)) {
742 ioc_set_batching(q, ioc);
743 blk_set_queue_full(q, rw);
744 } else {
745 if (may_queue != ELV_MQUEUE_MUST
746 && !ioc_batching(q, ioc)) {
747 /*
748 * The queue is full and the allocating
749 * process is not a "batcher", and not
750 * exempted by the IO scheduler
751 */
752 goto out;
753 }
754 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755 }
Thomas Maier79e2de42006-10-19 23:28:15 -0700756 blk_set_queue_congested(q, rw);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757 }
758
Jens Axboe082cf692005-06-28 16:35:11 +0200759 /*
760 * Only allow batching queuers to allocate up to 50% over the defined
761 * limit of requests, otherwise we could have thousands of requests
762 * allocated with any setting of ->nr_requests
763 */
Hugh Dickinsfd782a42005-06-29 15:15:40 +0100764 if (rl->count[rw] >= (3 * q->nr_requests / 2))
Jens Axboe082cf692005-06-28 16:35:11 +0200765 goto out;
Hugh Dickinsfd782a42005-06-29 15:15:40 +0100766
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767 rl->count[rw]++;
768 rl->starved[rw] = 0;
Tejun Heocb98fc82005-10-28 08:29:39 +0200769
Jens Axboe64521d12005-10-28 08:30:39 +0200770 priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
Tejun Heocb98fc82005-10-28 08:29:39 +0200771 if (priv)
772 rl->elvpriv++;
773
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774 spin_unlock_irq(q->queue_lock);
775
Jens Axboe7749a8d2006-12-13 13:02:26 +0100776 rq = blk_alloc_request(q, rw_flags, priv, gfp_mask);
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100777 if (unlikely(!rq)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 /*
779 * Allocation failed presumably due to memory. Undo anything
780 * we might have messed up.
781 *
782 * Allocating task should really be put onto the front of the
783 * wait queue, but this is pretty rare.
784 */
785 spin_lock_irq(q->queue_lock);
Tejun Heocb98fc82005-10-28 08:29:39 +0200786 freed_request(q, rw, priv);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700787
788 /*
789 * in the very unlikely event that allocation failed and no
790 * requests for this direction was pending, mark us starved
791 * so that freeing of a request in the other direction will
792 * notice us. another possible fix would be to split the
793 * rq mempool into READ and WRITE
794 */
795rq_starved:
796 if (unlikely(rl->count[rw] == 0))
797 rl->starved[rw] = 1;
798
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799 goto out;
800 }
801
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100802 /*
803 * ioc may be NULL here, and ioc_batching will be false. That's
804 * OK, if the queue is under the request limit then requests need
805 * not count toward the nr_batch_requests limit. There will always
806 * be some limit enforced by BLK_BATCH_TIME.
807 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808 if (ioc_batching(q, ioc))
809 ioc->nr_batch_requests--;
Jens Axboe6728cb02008-01-31 13:03:55 +0100810
Jens Axboe2056a782006-03-23 20:00:26 +0100811 blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700813 return rq;
814}
815
816/*
817 * No available requests for this queue, unplug the device and wait for some
818 * requests to become available.
Nick Piggind6344532005-06-28 20:45:14 -0700819 *
820 * Called with q->queue_lock held, and returns with it unlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821 */
Jens Axboe165125e2007-07-24 09:28:11 +0200822static struct request *get_request_wait(struct request_queue *q, int rw_flags,
Jens Axboe22e2c502005-06-27 10:55:12 +0200823 struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824{
Jens Axboe7749a8d2006-12-13 13:02:26 +0100825 const int rw = rw_flags & 0x01;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826 struct request *rq;
827
Jens Axboe7749a8d2006-12-13 13:02:26 +0100828 rq = get_request(q, rw_flags, bio, GFP_NOIO);
Nick Piggin450991b2005-06-28 20:45:13 -0700829 while (!rq) {
830 DEFINE_WAIT(wait);
Zhang, Yanmin05caf8d2008-05-22 15:13:29 +0200831 struct io_context *ioc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 struct request_list *rl = &q->rq;
833
834 prepare_to_wait_exclusive(&rl->wait[rw], &wait,
835 TASK_UNINTERRUPTIBLE);
836
Zhang, Yanmin05caf8d2008-05-22 15:13:29 +0200837 blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838
Zhang, Yanmin05caf8d2008-05-22 15:13:29 +0200839 __generic_unplug_device(q);
840 spin_unlock_irq(q->queue_lock);
841 io_schedule();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842
Zhang, Yanmin05caf8d2008-05-22 15:13:29 +0200843 /*
844 * After sleeping, we become a "batching" process and
845 * will be able to allocate at least one request, and
846 * up to a big batch of them for a small period time.
847 * See ioc_batching, ioc_set_batching
848 */
849 ioc = current_io_context(GFP_NOIO, q->node);
850 ioc_set_batching(q, ioc);
Jens Axboe2056a782006-03-23 20:00:26 +0100851
Zhang, Yanmin05caf8d2008-05-22 15:13:29 +0200852 spin_lock_irq(q->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700853 finish_wait(&rl->wait[rw], &wait);
Zhang, Yanmin05caf8d2008-05-22 15:13:29 +0200854
855 rq = get_request(q, rw_flags, bio, GFP_NOIO);
856 };
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857
858 return rq;
859}
860
Jens Axboe165125e2007-07-24 09:28:11 +0200861struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862{
863 struct request *rq;
864
865 BUG_ON(rw != READ && rw != WRITE);
866
Nick Piggind6344532005-06-28 20:45:14 -0700867 spin_lock_irq(q->queue_lock);
868 if (gfp_mask & __GFP_WAIT) {
Jens Axboe22e2c502005-06-27 10:55:12 +0200869 rq = get_request_wait(q, rw, NULL);
Nick Piggind6344532005-06-28 20:45:14 -0700870 } else {
Jens Axboe22e2c502005-06-27 10:55:12 +0200871 rq = get_request(q, rw, NULL, gfp_mask);
Nick Piggind6344532005-06-28 20:45:14 -0700872 if (!rq)
873 spin_unlock_irq(q->queue_lock);
874 }
875 /* q->queue_lock is unlocked at this point */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700876
877 return rq;
878}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700879EXPORT_SYMBOL(blk_get_request);
880
881/**
Jens Axboedc72ef42006-07-20 14:54:05 +0200882 * blk_start_queueing - initiate dispatch of requests to device
883 * @q: request queue to kick into gear
884 *
885 * This is basically a helper to remove the need to know whether a queue
886 * is plugged or not if someone just wants to initiate dispatch of requests
887 * for this queue.
888 *
889 * The queue lock must be held with interrupts disabled.
890 */
Jens Axboe165125e2007-07-24 09:28:11 +0200891void blk_start_queueing(struct request_queue *q)
Jens Axboedc72ef42006-07-20 14:54:05 +0200892{
893 if (!blk_queue_plugged(q))
894 q->request_fn(q);
895 else
896 __generic_unplug_device(q);
897}
898EXPORT_SYMBOL(blk_start_queueing);
899
900/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 * blk_requeue_request - put a request back on queue
902 * @q: request queue where request should be inserted
903 * @rq: request to be inserted
904 *
905 * Description:
906 * Drivers often keep queueing requests until the hardware cannot accept
907 * more, when that condition happens we need to put the request back
908 * on the queue. Must be called with queue lock held.
909 */
Jens Axboe165125e2007-07-24 09:28:11 +0200910void blk_requeue_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911{
Jens Axboe242f9dc2008-09-14 05:55:09 -0700912 blk_delete_timer(rq);
913 blk_clear_rq_complete(rq);
Jens Axboe2056a782006-03-23 20:00:26 +0100914 blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
915
Linus Torvalds1da177e2005-04-16 15:20:36 -0700916 if (blk_rq_tagged(rq))
917 blk_queue_end_tag(q, rq);
918
919 elv_requeue_request(q, rq);
920}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921EXPORT_SYMBOL(blk_requeue_request);
922
923/**
Randy Dunlap710027a2008-08-19 20:13:11 +0200924 * blk_insert_request - insert a special request into a request queue
Linus Torvalds1da177e2005-04-16 15:20:36 -0700925 * @q: request queue where request should be inserted
926 * @rq: request to be inserted
927 * @at_head: insert request at head or tail of queue
928 * @data: private data
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929 *
930 * Description:
931 * Many block devices need to execute commands asynchronously, so they don't
932 * block the whole kernel from preemption during request execution. This is
933 * accomplished normally by inserting aritficial requests tagged as
Randy Dunlap710027a2008-08-19 20:13:11 +0200934 * REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them
935 * be scheduled for actual execution by the request queue.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700936 *
937 * We have the option of inserting the head or the tail of the queue.
938 * Typically we use the tail for new ioctls and so forth. We use the head
939 * of the queue for things like a QUEUE_FULL message from a device, or a
940 * host that is unable to accept a particular command.
941 */
Jens Axboe165125e2007-07-24 09:28:11 +0200942void blk_insert_request(struct request_queue *q, struct request *rq,
Tejun Heo 867d1192005-04-24 02:06:05 -0500943 int at_head, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944{
Tejun Heo 867d1192005-04-24 02:06:05 -0500945 int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700946 unsigned long flags;
947
948 /*
949 * tell I/O scheduler that this isn't a regular read/write (ie it
950 * must not attempt merges on this) and that it acts as a soft
951 * barrier
952 */
Jens Axboe4aff5e22006-08-10 08:44:47 +0200953 rq->cmd_type = REQ_TYPE_SPECIAL;
954 rq->cmd_flags |= REQ_SOFTBARRIER;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700955
956 rq->special = data;
957
958 spin_lock_irqsave(q->queue_lock, flags);
959
960 /*
961 * If command is tagged, release the tag
962 */
Tejun Heo 867d1192005-04-24 02:06:05 -0500963 if (blk_rq_tagged(rq))
964 blk_queue_end_tag(q, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700965
Jerome Marchandb238b3d2007-10-23 15:05:46 +0200966 drive_stat_acct(rq, 1);
Tejun Heo 867d1192005-04-24 02:06:05 -0500967 __elv_add_request(q, rq, where, 0);
Jens Axboedc72ef42006-07-20 14:54:05 +0200968 blk_start_queueing(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969 spin_unlock_irqrestore(q->queue_lock, flags);
970}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700971EXPORT_SYMBOL(blk_insert_request);
972
Linus Torvalds1da177e2005-04-16 15:20:36 -0700973/*
974 * add-request adds a request to the linked list.
975 * queue lock is held and interrupts disabled, as we muck with the
976 * request queue list.
977 */
Jens Axboe6728cb02008-01-31 13:03:55 +0100978static inline void add_request(struct request_queue *q, struct request *req)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700979{
Jerome Marchandb238b3d2007-10-23 15:05:46 +0200980 drive_stat_acct(req, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982 /*
983 * elevator indicated where it wants this request to be
984 * inserted at elevator_merge time
985 */
986 __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0);
987}
Jens Axboe6728cb02008-01-31 13:03:55 +0100988
Tejun Heo074a7ac2008-08-25 19:56:14 +0900989static void part_round_stats_single(int cpu, struct hd_struct *part,
990 unsigned long now)
991{
992 if (now == part->stamp)
993 return;
994
995 if (part->in_flight) {
996 __part_stat_add(cpu, part, time_in_queue,
997 part->in_flight * (now - part->stamp));
998 __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
999 }
1000 part->stamp = now;
1001}
1002
1003/**
1004 * part_round_stats() - Round off the performance stats on a struct
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005 * disk_stats.
1006 *
1007 * The average IO queue length and utilisation statistics are maintained
1008 * by observing the current state of the queue length and the amount of
1009 * time it has been in this state for.
1010 *
1011 * Normally, that accounting is done on IO completion, but that can result
1012 * in more than a second's worth of IO being accounted for within any one
1013 * second, leading to >100% utilisation. To deal with that, we call this
1014 * function to do a round-off before returning the results when reading
1015 * /proc/diskstats. This accounts immediately for all queue usage up to
1016 * the current jiffies and restarts the counters again.
1017 */
Tejun Heoc9959052008-08-25 19:47:21 +09001018void part_round_stats(int cpu, struct hd_struct *part)
Jerome Marchand6f2576a2008-02-08 11:04:35 +01001019{
1020 unsigned long now = jiffies;
1021
Tejun Heo074a7ac2008-08-25 19:56:14 +09001022 if (part->partno)
1023 part_round_stats_single(cpu, &part_to_disk(part)->part0, now);
1024 part_round_stats_single(cpu, part, now);
Jerome Marchand6f2576a2008-02-08 11:04:35 +01001025}
Tejun Heo074a7ac2008-08-25 19:56:14 +09001026EXPORT_SYMBOL_GPL(part_round_stats);
Jerome Marchand6f2576a2008-02-08 11:04:35 +01001027
Linus Torvalds1da177e2005-04-16 15:20:36 -07001028/*
1029 * queue lock must be held
1030 */
Jens Axboe165125e2007-07-24 09:28:11 +02001031void __blk_put_request(struct request_queue *q, struct request *req)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001032{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001033 if (unlikely(!q))
1034 return;
1035 if (unlikely(--req->ref_count))
1036 return;
1037
Tejun Heo8922e162005-10-20 16:23:44 +02001038 elv_completed_request(q, req);
1039
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040 /*
1041 * Request may not have originated from ll_rw_blk. if not,
1042 * it didn't come out of our reserved rq pools
1043 */
Jens Axboe49171e52006-08-10 08:59:11 +02001044 if (req->cmd_flags & REQ_ALLOCED) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001045 int rw = rq_data_dir(req);
Jens Axboe4aff5e22006-08-10 08:44:47 +02001046 int priv = req->cmd_flags & REQ_ELVPRIV;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001047
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048 BUG_ON(!list_empty(&req->queuelist));
Jens Axboe98170642006-07-28 09:23:08 +02001049 BUG_ON(!hlist_unhashed(&req->hash));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050
1051 blk_free_request(q, req);
Tejun Heocb98fc82005-10-28 08:29:39 +02001052 freed_request(q, rw, priv);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001053 }
1054}
Mike Christie6e39b692005-11-11 05:30:24 -06001055EXPORT_SYMBOL_GPL(__blk_put_request);
1056
Linus Torvalds1da177e2005-04-16 15:20:36 -07001057void blk_put_request(struct request *req)
1058{
Tejun Heo8922e162005-10-20 16:23:44 +02001059 unsigned long flags;
Jens Axboe165125e2007-07-24 09:28:11 +02001060 struct request_queue *q = req->q;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061
FUJITA Tomonori52a93ba2008-07-15 21:21:45 +02001062 spin_lock_irqsave(q->queue_lock, flags);
1063 __blk_put_request(q, req);
1064 spin_unlock_irqrestore(q->queue_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001066EXPORT_SYMBOL(blk_put_request);
1067
Jens Axboe86db1e22008-01-29 14:53:40 +01001068void init_request_from_bio(struct request *req, struct bio *bio)
Tejun Heo52d9e672006-01-06 09:49:58 +01001069{
Jens Axboec7c22e42008-09-13 20:26:01 +02001070 req->cpu = bio->bi_comp_cpu;
Jens Axboe4aff5e22006-08-10 08:44:47 +02001071 req->cmd_type = REQ_TYPE_FS;
Tejun Heo52d9e672006-01-06 09:49:58 +01001072
1073 /*
1074 * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
1075 */
1076 if (bio_rw_ahead(bio) || bio_failfast(bio))
Jens Axboe4aff5e22006-08-10 08:44:47 +02001077 req->cmd_flags |= REQ_FAILFAST;
Tejun Heo52d9e672006-01-06 09:49:58 +01001078
1079 /*
1080 * REQ_BARRIER implies no merging, but lets make it explicit
1081 */
David Woodhousefb2dce82008-08-05 18:01:53 +01001082 if (unlikely(bio_discard(bio))) {
David Woodhousee17fc0a2008-08-09 16:42:20 +01001083 req->cmd_flags |= REQ_DISCARD;
1084 if (bio_barrier(bio))
1085 req->cmd_flags |= REQ_SOFTBARRIER;
David Woodhousefb2dce82008-08-05 18:01:53 +01001086 req->q->prepare_discard_fn(req->q, req);
David Woodhousee17fc0a2008-08-09 16:42:20 +01001087 } else if (unlikely(bio_barrier(bio)))
1088 req->cmd_flags |= (REQ_HARDBARRIER | REQ_NOMERGE);
Tejun Heo52d9e672006-01-06 09:49:58 +01001089
Jens Axboeb31dc662006-06-13 08:26:10 +02001090 if (bio_sync(bio))
Jens Axboe4aff5e22006-08-10 08:44:47 +02001091 req->cmd_flags |= REQ_RW_SYNC;
Jens Axboe5404bc72006-08-10 09:01:02 +02001092 if (bio_rw_meta(bio))
1093 req->cmd_flags |= REQ_RW_META;
Jens Axboeb31dc662006-06-13 08:26:10 +02001094
Tejun Heo52d9e672006-01-06 09:49:58 +01001095 req->errors = 0;
1096 req->hard_sector = req->sector = bio->bi_sector;
Tejun Heo52d9e672006-01-06 09:49:58 +01001097 req->ioprio = bio_prio(bio);
Tejun Heo52d9e672006-01-06 09:49:58 +01001098 req->start_time = jiffies;
NeilBrownbc1c56f2007-08-16 13:31:30 +02001099 blk_rq_bio_prep(req->q, req, bio);
Tejun Heo52d9e672006-01-06 09:49:58 +01001100}
1101
Jens Axboe165125e2007-07-24 09:28:11 +02001102static int __make_request(struct request_queue *q, struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001103{
Nick Piggin450991b2005-06-28 20:45:13 -07001104 struct request *req;
David Woodhousefb2dce82008-08-05 18:01:53 +01001105 int el_ret, nr_sectors, barrier, discard, err;
Jens Axboe51da90f2006-07-18 04:14:45 +02001106 const unsigned short prio = bio_prio(bio);
1107 const int sync = bio_sync(bio);
Jens Axboe7749a8d2006-12-13 13:02:26 +01001108 int rw_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001109
Linus Torvalds1da177e2005-04-16 15:20:36 -07001110 nr_sectors = bio_sectors(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001111
1112 /*
1113 * low level driver can indicate that it wants pages above a
1114 * certain limit bounced to low memory (ie for highmem, or even
1115 * ISA dma in theory)
1116 */
1117 blk_queue_bounce(q, &bio);
1118
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119 barrier = bio_barrier(bio);
David Woodhousee17fc0a2008-08-09 16:42:20 +01001120 if (unlikely(barrier) && bio_has_data(bio) &&
1121 (q->next_ordered == QUEUE_ORDERED_NONE)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122 err = -EOPNOTSUPP;
1123 goto end_io;
1124 }
1125
David Woodhousefb2dce82008-08-05 18:01:53 +01001126 discard = bio_discard(bio);
1127 if (unlikely(discard) && !q->prepare_discard_fn) {
1128 err = -EOPNOTSUPP;
1129 goto end_io;
1130 }
1131
Linus Torvalds1da177e2005-04-16 15:20:36 -07001132 spin_lock_irq(q->queue_lock);
1133
Nick Piggin450991b2005-06-28 20:45:13 -07001134 if (unlikely(barrier) || elv_queue_empty(q))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001135 goto get_rq;
1136
1137 el_ret = elv_merge(q, &req, bio);
1138 switch (el_ret) {
Jens Axboe6728cb02008-01-31 13:03:55 +01001139 case ELEVATOR_BACK_MERGE:
1140 BUG_ON(!rq_mergeable(req));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141
Jens Axboe6728cb02008-01-31 13:03:55 +01001142 if (!ll_back_merge_fn(q, req, bio))
1143 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001144
Jens Axboe6728cb02008-01-31 13:03:55 +01001145 blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
Jens Axboe2056a782006-03-23 20:00:26 +01001146
Jens Axboe6728cb02008-01-31 13:03:55 +01001147 req->biotail->bi_next = bio;
1148 req->biotail = bio;
1149 req->nr_sectors = req->hard_nr_sectors += nr_sectors;
1150 req->ioprio = ioprio_best(req->ioprio, prio);
Jens Axboeab780f12008-08-26 10:25:02 +02001151 if (!blk_rq_cpu_valid(req))
1152 req->cpu = bio->bi_comp_cpu;
Jens Axboe6728cb02008-01-31 13:03:55 +01001153 drive_stat_acct(req, 0);
1154 if (!attempt_back_merge(q, req))
1155 elv_merged_request(q, req, el_ret);
1156 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001157
Jens Axboe6728cb02008-01-31 13:03:55 +01001158 case ELEVATOR_FRONT_MERGE:
1159 BUG_ON(!rq_mergeable(req));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001160
Jens Axboe6728cb02008-01-31 13:03:55 +01001161 if (!ll_front_merge_fn(q, req, bio))
1162 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163
Jens Axboe6728cb02008-01-31 13:03:55 +01001164 blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
Jens Axboe2056a782006-03-23 20:00:26 +01001165
Jens Axboe6728cb02008-01-31 13:03:55 +01001166 bio->bi_next = req->bio;
1167 req->bio = bio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001168
Jens Axboe6728cb02008-01-31 13:03:55 +01001169 /*
1170 * may not be valid. if the low level driver said
1171 * it didn't need a bounce buffer then it better
1172 * not touch req->buffer either...
1173 */
1174 req->buffer = bio_data(bio);
1175 req->current_nr_sectors = bio_cur_sectors(bio);
1176 req->hard_cur_sectors = req->current_nr_sectors;
1177 req->sector = req->hard_sector = bio->bi_sector;
1178 req->nr_sectors = req->hard_nr_sectors += nr_sectors;
1179 req->ioprio = ioprio_best(req->ioprio, prio);
Jens Axboeab780f12008-08-26 10:25:02 +02001180 if (!blk_rq_cpu_valid(req))
1181 req->cpu = bio->bi_comp_cpu;
Jens Axboe6728cb02008-01-31 13:03:55 +01001182 drive_stat_acct(req, 0);
1183 if (!attempt_front_merge(q, req))
1184 elv_merged_request(q, req, el_ret);
1185 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001186
Jens Axboe6728cb02008-01-31 13:03:55 +01001187 /* ELV_NO_MERGE: elevator says don't/can't merge. */
1188 default:
1189 ;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190 }
1191
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192get_rq:
Nick Piggin450991b2005-06-28 20:45:13 -07001193 /*
Jens Axboe7749a8d2006-12-13 13:02:26 +01001194 * This sync check and mask will be re-done in init_request_from_bio(),
1195 * but we need to set it earlier to expose the sync flag to the
1196 * rq allocator and io schedulers.
1197 */
1198 rw_flags = bio_data_dir(bio);
1199 if (sync)
1200 rw_flags |= REQ_RW_SYNC;
1201
1202 /*
Nick Piggin450991b2005-06-28 20:45:13 -07001203 * Grab a free request. This is might sleep but can not fail.
Nick Piggind6344532005-06-28 20:45:14 -07001204 * Returns with the queue unlocked.
Nick Piggin450991b2005-06-28 20:45:13 -07001205 */
Jens Axboe7749a8d2006-12-13 13:02:26 +01001206 req = get_request_wait(q, rw_flags, bio);
Nick Piggind6344532005-06-28 20:45:14 -07001207
Nick Piggin450991b2005-06-28 20:45:13 -07001208 /*
1209 * After dropping the lock and possibly sleeping here, our request
1210 * may now be mergeable after it had proven unmergeable (above).
1211 * We don't worry about that case for efficiency. It won't happen
1212 * often, and the elevators are able to handle it.
1213 */
Tejun Heo52d9e672006-01-06 09:49:58 +01001214 init_request_from_bio(req, bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001215
Nick Piggin450991b2005-06-28 20:45:13 -07001216 spin_lock_irq(q->queue_lock);
Jens Axboec7c22e42008-09-13 20:26:01 +02001217 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) ||
1218 bio_flagged(bio, BIO_CPU_AFFINE))
1219 req->cpu = blk_cpu_to_group(smp_processor_id());
Nick Piggin450991b2005-06-28 20:45:13 -07001220 if (elv_queue_empty(q))
1221 blk_plug_device(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001222 add_request(q, req);
1223out:
Jens Axboe4a534f92005-04-16 15:25:40 -07001224 if (sync)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001225 __generic_unplug_device(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001226 spin_unlock_irq(q->queue_lock);
1227 return 0;
1228
1229end_io:
NeilBrown6712ecf2007-09-27 12:47:43 +02001230 bio_endio(bio, err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001231 return 0;
1232}
1233
1234/*
1235 * If bio->bi_dev is a partition, remap the location
1236 */
1237static inline void blk_partition_remap(struct bio *bio)
1238{
1239 struct block_device *bdev = bio->bi_bdev;
1240
Jens Axboebf2de6f2007-09-27 13:01:25 +02001241 if (bio_sectors(bio) && bdev != bdev->bd_contains) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242 struct hd_struct *p = bdev->bd_part;
Jens Axboea3623572005-11-01 09:26:16 +01001243
Linus Torvalds1da177e2005-04-16 15:20:36 -07001244 bio->bi_sector += p->start_sect;
1245 bio->bi_bdev = bdev->bd_contains;
Alan D. Brunellec7149d62007-08-07 15:30:23 +02001246
1247 blk_add_trace_remap(bdev_get_queue(bio->bi_bdev), bio,
1248 bdev->bd_dev, bio->bi_sector,
1249 bio->bi_sector - p->start_sect);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001250 }
1251}
1252
Linus Torvalds1da177e2005-04-16 15:20:36 -07001253static void handle_bad_sector(struct bio *bio)
1254{
1255 char b[BDEVNAME_SIZE];
1256
1257 printk(KERN_INFO "attempt to access beyond end of device\n");
1258 printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
1259 bdevname(bio->bi_bdev, b),
1260 bio->bi_rw,
1261 (unsigned long long)bio->bi_sector + bio_sectors(bio),
1262 (long long)(bio->bi_bdev->bd_inode->i_size >> 9));
1263
1264 set_bit(BIO_EOF, &bio->bi_flags);
1265}
1266
Akinobu Mitac17bb492006-12-08 02:39:46 -08001267#ifdef CONFIG_FAIL_MAKE_REQUEST
1268
1269static DECLARE_FAULT_ATTR(fail_make_request);
1270
1271static int __init setup_fail_make_request(char *str)
1272{
1273 return setup_fault_attr(&fail_make_request, str);
1274}
1275__setup("fail_make_request=", setup_fail_make_request);
1276
1277static int should_fail_request(struct bio *bio)
1278{
Tejun Heoeddb2e22008-08-25 19:56:13 +09001279 struct hd_struct *part = bio->bi_bdev->bd_part;
1280
1281 if (part_to_disk(part)->part0.make_it_fail || part->make_it_fail)
Akinobu Mitac17bb492006-12-08 02:39:46 -08001282 return should_fail(&fail_make_request, bio->bi_size);
1283
1284 return 0;
1285}
1286
1287static int __init fail_make_request_debugfs(void)
1288{
1289 return init_fault_attr_dentries(&fail_make_request,
1290 "fail_make_request");
1291}
1292
1293late_initcall(fail_make_request_debugfs);
1294
1295#else /* CONFIG_FAIL_MAKE_REQUEST */
1296
1297static inline int should_fail_request(struct bio *bio)
1298{
1299 return 0;
1300}
1301
1302#endif /* CONFIG_FAIL_MAKE_REQUEST */
1303
Jens Axboec07e2b42007-07-18 13:27:58 +02001304/*
1305 * Check whether this bio extends beyond the end of the device.
1306 */
1307static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
1308{
1309 sector_t maxsector;
1310
1311 if (!nr_sectors)
1312 return 0;
1313
1314 /* Test device or partition size, when known. */
1315 maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
1316 if (maxsector) {
1317 sector_t sector = bio->bi_sector;
1318
1319 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
1320 /*
1321 * This may well happen - the kernel calls bread()
1322 * without checking the size of the device, e.g., when
1323 * mounting a device.
1324 */
1325 handle_bad_sector(bio);
1326 return 1;
1327 }
1328 }
1329
1330 return 0;
1331}
1332
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333/**
Randy Dunlap710027a2008-08-19 20:13:11 +02001334 * generic_make_request - hand a buffer to its device driver for I/O
Linus Torvalds1da177e2005-04-16 15:20:36 -07001335 * @bio: The bio describing the location in memory and on the device.
1336 *
1337 * generic_make_request() is used to make I/O requests of block
1338 * devices. It is passed a &struct bio, which describes the I/O that needs
1339 * to be done.
1340 *
1341 * generic_make_request() does not return any status. The
1342 * success/failure status of the request, along with notification of
1343 * completion, is delivered asynchronously through the bio->bi_end_io
1344 * function described (one day) else where.
1345 *
1346 * The caller of generic_make_request must make sure that bi_io_vec
1347 * are set to describe the memory buffer, and that bi_dev and bi_sector are
1348 * set to describe the device address, and the
1349 * bi_end_io and optionally bi_private are set to describe how
1350 * completion notification should be signaled.
1351 *
1352 * generic_make_request and the drivers it calls may use bi_next if this
1353 * bio happens to be merged with someone else, and may change bi_dev and
1354 * bi_sector for remaps as it sees fit. So the values of these fields
1355 * should NOT be depended on after the call to generic_make_request.
1356 */
Neil Brownd89d8792007-05-01 09:53:42 +02001357static inline void __generic_make_request(struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358{
Jens Axboe165125e2007-07-24 09:28:11 +02001359 struct request_queue *q;
NeilBrown5ddfe962006-10-30 22:07:21 -08001360 sector_t old_sector;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361 int ret, nr_sectors = bio_sectors(bio);
Jens Axboe2056a782006-03-23 20:00:26 +01001362 dev_t old_dev;
Jens Axboe51fd77b2007-11-02 08:49:08 +01001363 int err = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364
1365 might_sleep();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366
Jens Axboec07e2b42007-07-18 13:27:58 +02001367 if (bio_check_eod(bio, nr_sectors))
1368 goto end_io;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001369
1370 /*
1371 * Resolve the mapping until finished. (drivers are
1372 * still free to implement/resolve their own stacking
1373 * by explicitly returning 0)
1374 *
1375 * NOTE: we don't repeat the blk_size check for each new device.
1376 * Stacking drivers are expected to know what they are doing.
1377 */
NeilBrown5ddfe962006-10-30 22:07:21 -08001378 old_sector = -1;
Jens Axboe2056a782006-03-23 20:00:26 +01001379 old_dev = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380 do {
1381 char b[BDEVNAME_SIZE];
1382
1383 q = bdev_get_queue(bio->bi_bdev);
1384 if (!q) {
1385 printk(KERN_ERR
1386 "generic_make_request: Trying to access "
1387 "nonexistent block-device %s (%Lu)\n",
1388 bdevname(bio->bi_bdev, b),
1389 (long long) bio->bi_sector);
1390end_io:
Jens Axboe51fd77b2007-11-02 08:49:08 +01001391 bio_endio(bio, err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001392 break;
1393 }
1394
Jens Axboe4fa253f2007-07-18 13:13:10 +02001395 if (unlikely(nr_sectors > q->max_hw_sectors)) {
Jens Axboe6728cb02008-01-31 13:03:55 +01001396 printk(KERN_ERR "bio too big device %s (%u > %u)\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001397 bdevname(bio->bi_bdev, b),
1398 bio_sectors(bio),
1399 q->max_hw_sectors);
1400 goto end_io;
1401 }
1402
Nick Pigginfde6ad22005-06-23 00:08:53 -07001403 if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001404 goto end_io;
1405
Akinobu Mitac17bb492006-12-08 02:39:46 -08001406 if (should_fail_request(bio))
1407 goto end_io;
1408
Linus Torvalds1da177e2005-04-16 15:20:36 -07001409 /*
1410 * If this device has partitions, remap block n
1411 * of partition p to block n+start(p) of the disk.
1412 */
1413 blk_partition_remap(bio);
1414
Martin K. Petersen7ba1ba12008-06-30 20:04:41 +02001415 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio))
1416 goto end_io;
1417
NeilBrown5ddfe962006-10-30 22:07:21 -08001418 if (old_sector != -1)
Jens Axboe4fa253f2007-07-18 13:13:10 +02001419 blk_add_trace_remap(q, bio, old_dev, bio->bi_sector,
NeilBrown5ddfe962006-10-30 22:07:21 -08001420 old_sector);
Jens Axboe2056a782006-03-23 20:00:26 +01001421
1422 blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
1423
NeilBrown5ddfe962006-10-30 22:07:21 -08001424 old_sector = bio->bi_sector;
Jens Axboe2056a782006-03-23 20:00:26 +01001425 old_dev = bio->bi_bdev->bd_dev;
1426
Jens Axboec07e2b42007-07-18 13:27:58 +02001427 if (bio_check_eod(bio, nr_sectors))
1428 goto end_io;
David Woodhousefb2dce82008-08-05 18:01:53 +01001429 if ((bio_empty_barrier(bio) && !q->prepare_flush_fn) ||
1430 (bio_discard(bio) && !q->prepare_discard_fn)) {
Jens Axboe51fd77b2007-11-02 08:49:08 +01001431 err = -EOPNOTSUPP;
1432 goto end_io;
1433 }
NeilBrown5ddfe962006-10-30 22:07:21 -08001434
Linus Torvalds1da177e2005-04-16 15:20:36 -07001435 ret = q->make_request_fn(q, bio);
1436 } while (ret);
1437}
1438
Neil Brownd89d8792007-05-01 09:53:42 +02001439/*
1440 * We only want one ->make_request_fn to be active at a time,
1441 * else stack usage with stacked devices could be a problem.
1442 * So use current->bio_{list,tail} to keep a list of requests
1443 * submited by a make_request_fn function.
1444 * current->bio_tail is also used as a flag to say if
1445 * generic_make_request is currently active in this task or not.
1446 * If it is NULL, then no make_request is active. If it is non-NULL,
1447 * then a make_request is active, and new requests should be added
1448 * at the tail
1449 */
1450void generic_make_request(struct bio *bio)
1451{
1452 if (current->bio_tail) {
1453 /* make_request is active */
1454 *(current->bio_tail) = bio;
1455 bio->bi_next = NULL;
1456 current->bio_tail = &bio->bi_next;
1457 return;
1458 }
1459 /* following loop may be a bit non-obvious, and so deserves some
1460 * explanation.
1461 * Before entering the loop, bio->bi_next is NULL (as all callers
1462 * ensure that) so we have a list with a single bio.
1463 * We pretend that we have just taken it off a longer list, so
1464 * we assign bio_list to the next (which is NULL) and bio_tail
1465 * to &bio_list, thus initialising the bio_list of new bios to be
1466 * added. __generic_make_request may indeed add some more bios
1467 * through a recursive call to generic_make_request. If it
1468 * did, we find a non-NULL value in bio_list and re-enter the loop
1469 * from the top. In this case we really did just take the bio
1470 * of the top of the list (no pretending) and so fixup bio_list and
1471 * bio_tail or bi_next, and call into __generic_make_request again.
1472 *
1473 * The loop was structured like this to make only one call to
1474 * __generic_make_request (which is important as it is large and
1475 * inlined) and to keep the structure simple.
1476 */
1477 BUG_ON(bio->bi_next);
1478 do {
1479 current->bio_list = bio->bi_next;
1480 if (bio->bi_next == NULL)
1481 current->bio_tail = &current->bio_list;
1482 else
1483 bio->bi_next = NULL;
1484 __generic_make_request(bio);
1485 bio = current->bio_list;
1486 } while (bio);
1487 current->bio_tail = NULL; /* deactivate */
1488}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001489EXPORT_SYMBOL(generic_make_request);
1490
1491/**
Randy Dunlap710027a2008-08-19 20:13:11 +02001492 * submit_bio - submit a bio to the block device layer for I/O
Linus Torvalds1da177e2005-04-16 15:20:36 -07001493 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
1494 * @bio: The &struct bio which describes the I/O
1495 *
1496 * submit_bio() is very similar in purpose to generic_make_request(), and
1497 * uses that function to do most of the work. Both are fairly rough
Randy Dunlap710027a2008-08-19 20:13:11 +02001498 * interfaces; @bio must be presetup and ready for I/O.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001499 *
1500 */
1501void submit_bio(int rw, struct bio *bio)
1502{
1503 int count = bio_sectors(bio);
1504
Jens Axboe22e2c502005-06-27 10:55:12 +02001505 bio->bi_rw |= rw;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001506
Jens Axboebf2de6f2007-09-27 13:01:25 +02001507 /*
1508 * If it's a regular read/write or a barrier with data attached,
1509 * go through the normal accounting stuff before submission.
1510 */
Jens Axboea9c701e2008-08-08 11:04:44 +02001511 if (bio_has_data(bio)) {
Jens Axboebf2de6f2007-09-27 13:01:25 +02001512 if (rw & WRITE) {
1513 count_vm_events(PGPGOUT, count);
1514 } else {
1515 task_io_account_read(bio->bi_size);
1516 count_vm_events(PGPGIN, count);
1517 }
1518
1519 if (unlikely(block_dump)) {
1520 char b[BDEVNAME_SIZE];
1521 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07001522 current->comm, task_pid_nr(current),
Jens Axboebf2de6f2007-09-27 13:01:25 +02001523 (rw & WRITE) ? "WRITE" : "READ",
1524 (unsigned long long)bio->bi_sector,
Jens Axboe6728cb02008-01-31 13:03:55 +01001525 bdevname(bio->bi_bdev, b));
Jens Axboebf2de6f2007-09-27 13:01:25 +02001526 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527 }
1528
1529 generic_make_request(bio);
1530}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001531EXPORT_SYMBOL(submit_bio);
1532
Kiyoshi Ueda3bcddea2007-12-11 17:52:28 -05001533/**
Kiyoshi Ueda82124d62008-09-18 10:45:38 -04001534 * blk_rq_check_limits - Helper function to check a request for the queue limit
1535 * @q: the queue
1536 * @rq: the request being checked
1537 *
1538 * Description:
1539 * @rq may have been made based on weaker limitations of upper-level queues
1540 * in request stacking drivers, and it may violate the limitation of @q.
1541 * Since the block layer and the underlying device driver trust @rq
1542 * after it is inserted to @q, it should be checked against @q before
1543 * the insertion using this generic function.
1544 *
1545 * This function should also be useful for request stacking drivers
1546 * in some cases below, so export this fuction.
1547 * Request stacking drivers like request-based dm may change the queue
1548 * limits while requests are in the queue (e.g. dm's table swapping).
1549 * Such request stacking drivers should check those requests agaist
1550 * the new queue limits again when they dispatch those requests,
1551 * although such checkings are also done against the old queue limits
1552 * when submitting requests.
1553 */
1554int blk_rq_check_limits(struct request_queue *q, struct request *rq)
1555{
1556 if (rq->nr_sectors > q->max_sectors ||
1557 rq->data_len > q->max_hw_sectors << 9) {
1558 printk(KERN_ERR "%s: over max size limit.\n", __func__);
1559 return -EIO;
1560 }
1561
1562 /*
1563 * queue's settings related to segment counting like q->bounce_pfn
1564 * may differ from that of other stacking queues.
1565 * Recalculate it to check the request correctly on this queue's
1566 * limitation.
1567 */
1568 blk_recalc_rq_segments(rq);
1569 if (rq->nr_phys_segments > q->max_phys_segments ||
1570 rq->nr_phys_segments > q->max_hw_segments) {
1571 printk(KERN_ERR "%s: over max segments limit.\n", __func__);
1572 return -EIO;
1573 }
1574
1575 return 0;
1576}
1577EXPORT_SYMBOL_GPL(blk_rq_check_limits);
1578
1579/**
1580 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
1581 * @q: the queue to submit the request
1582 * @rq: the request being queued
1583 */
1584int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
1585{
1586 unsigned long flags;
1587
1588 if (blk_rq_check_limits(q, rq))
1589 return -EIO;
1590
1591#ifdef CONFIG_FAIL_MAKE_REQUEST
1592 if (rq->rq_disk && rq->rq_disk->part0.make_it_fail &&
1593 should_fail(&fail_make_request, blk_rq_bytes(rq)))
1594 return -EIO;
1595#endif
1596
1597 spin_lock_irqsave(q->queue_lock, flags);
1598
1599 /*
1600 * Submitting request must be dequeued before calling this function
1601 * because it will be linked to another request_queue
1602 */
1603 BUG_ON(blk_queued_rq(rq));
1604
1605 drive_stat_acct(rq, 1);
1606 __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0);
1607
1608 spin_unlock_irqrestore(q->queue_lock, flags);
1609
1610 return 0;
1611}
1612EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
1613
1614/**
Kiyoshi Ueda3bcddea2007-12-11 17:52:28 -05001615 * __end_that_request_first - end I/O on a request
1616 * @req: the request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02001617 * @error: %0 for success, < %0 for error
Kiyoshi Ueda3bcddea2007-12-11 17:52:28 -05001618 * @nr_bytes: number of bytes to complete
1619 *
1620 * Description:
1621 * Ends I/O on a number of bytes attached to @req, and sets it up
1622 * for the next range of segments (if any) in the cluster.
1623 *
1624 * Return:
Randy Dunlap710027a2008-08-19 20:13:11 +02001625 * %0 - we are done with this request, call end_that_request_last()
1626 * %1 - still buffers pending for this request
Kiyoshi Ueda3bcddea2007-12-11 17:52:28 -05001627 **/
Kiyoshi Ueda5450d3e2007-12-11 17:53:03 -05001628static int __end_that_request_first(struct request *req, int error,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001629 int nr_bytes)
1630{
Kiyoshi Ueda5450d3e2007-12-11 17:53:03 -05001631 int total_bytes, bio_nbytes, next_idx = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001632 struct bio *bio;
1633
Jens Axboe2056a782006-03-23 20:00:26 +01001634 blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE);
1635
Linus Torvalds1da177e2005-04-16 15:20:36 -07001636 /*
Randy Dunlap710027a2008-08-19 20:13:11 +02001637 * for a REQ_TYPE_BLOCK_PC request, we want to carry any eventual
Linus Torvalds1da177e2005-04-16 15:20:36 -07001638 * sense key with us all the way through
1639 */
1640 if (!blk_pc_request(req))
1641 req->errors = 0;
1642
Jens Axboe6728cb02008-01-31 13:03:55 +01001643 if (error && (blk_fs_request(req) && !(req->cmd_flags & REQ_QUIET))) {
1644 printk(KERN_ERR "end_request: I/O error, dev %s, sector %llu\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645 req->rq_disk ? req->rq_disk->disk_name : "?",
1646 (unsigned long long)req->sector);
1647 }
1648
Jens Axboed72d9042005-11-01 08:35:42 +01001649 if (blk_fs_request(req) && req->rq_disk) {
Jens Axboea3623572005-11-01 09:26:16 +01001650 const int rw = rq_data_dir(req);
Tejun Heoe71bf0d2008-09-03 09:03:02 +02001651 struct hd_struct *part;
Tejun Heoc9959052008-08-25 19:47:21 +09001652 int cpu;
Jens Axboea3623572005-11-01 09:26:16 +01001653
Tejun Heo074a7ac2008-08-25 19:56:14 +09001654 cpu = part_stat_lock();
Tejun Heoe71bf0d2008-09-03 09:03:02 +02001655 part = disk_map_sector_rcu(req->rq_disk, req->sector);
Tejun Heo074a7ac2008-08-25 19:56:14 +09001656 part_stat_add(cpu, part, sectors[rw], nr_bytes >> 9);
1657 part_stat_unlock();
Jens Axboed72d9042005-11-01 08:35:42 +01001658 }
1659
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660 total_bytes = bio_nbytes = 0;
1661 while ((bio = req->bio) != NULL) {
1662 int nbytes;
1663
Jens Axboebf2de6f2007-09-27 13:01:25 +02001664 /*
1665 * For an empty barrier request, the low level driver must
1666 * store a potential error location in ->sector. We pass
1667 * that back up in ->bi_sector.
1668 */
1669 if (blk_empty_barrier(req))
1670 bio->bi_sector = req->sector;
1671
Linus Torvalds1da177e2005-04-16 15:20:36 -07001672 if (nr_bytes >= bio->bi_size) {
1673 req->bio = bio->bi_next;
1674 nbytes = bio->bi_size;
NeilBrown5bb23a62007-09-27 12:46:13 +02001675 req_bio_endio(req, bio, nbytes, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001676 next_idx = 0;
1677 bio_nbytes = 0;
1678 } else {
1679 int idx = bio->bi_idx + next_idx;
1680
1681 if (unlikely(bio->bi_idx >= bio->bi_vcnt)) {
1682 blk_dump_rq_flags(req, "__end_that");
Jens Axboe6728cb02008-01-31 13:03:55 +01001683 printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n",
Harvey Harrison24c03d42008-05-01 04:35:17 -07001684 __func__, bio->bi_idx, bio->bi_vcnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001685 break;
1686 }
1687
1688 nbytes = bio_iovec_idx(bio, idx)->bv_len;
1689 BIO_BUG_ON(nbytes > bio->bi_size);
1690
1691 /*
1692 * not a complete bvec done
1693 */
1694 if (unlikely(nbytes > nr_bytes)) {
1695 bio_nbytes += nr_bytes;
1696 total_bytes += nr_bytes;
1697 break;
1698 }
1699
1700 /*
1701 * advance to the next vector
1702 */
1703 next_idx++;
1704 bio_nbytes += nbytes;
1705 }
1706
1707 total_bytes += nbytes;
1708 nr_bytes -= nbytes;
1709
Jens Axboe6728cb02008-01-31 13:03:55 +01001710 bio = req->bio;
1711 if (bio) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712 /*
1713 * end more in this run, or just return 'not-done'
1714 */
1715 if (unlikely(nr_bytes <= 0))
1716 break;
1717 }
1718 }
1719
1720 /*
1721 * completely done
1722 */
1723 if (!req->bio)
1724 return 0;
1725
1726 /*
1727 * if the request wasn't completed, update state
1728 */
1729 if (bio_nbytes) {
NeilBrown5bb23a62007-09-27 12:46:13 +02001730 req_bio_endio(req, bio, bio_nbytes, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731 bio->bi_idx += next_idx;
1732 bio_iovec(bio)->bv_offset += nr_bytes;
1733 bio_iovec(bio)->bv_len -= nr_bytes;
1734 }
1735
1736 blk_recalc_rq_sectors(req, total_bytes >> 9);
1737 blk_recalc_rq_segments(req);
1738 return 1;
1739}
1740
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741/*
1742 * queue lock must be held
1743 */
Kiyoshi Ueda5450d3e2007-12-11 17:53:03 -05001744static void end_that_request_last(struct request *req, int error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001745{
1746 struct gendisk *disk = req->rq_disk;
Tejun Heo8ffdc652006-01-06 09:49:03 +01001747
Jens Axboe242f9dc2008-09-14 05:55:09 -07001748 blk_delete_timer(req);
1749
Kiyoshi Uedab8286232007-12-11 17:53:24 -05001750 if (blk_rq_tagged(req))
1751 blk_queue_end_tag(req->q, req);
1752
1753 if (blk_queued_rq(req))
1754 blkdev_dequeue_request(req);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001755
1756 if (unlikely(laptop_mode) && blk_fs_request(req))
1757 laptop_io_completion();
1758
Jens Axboefd0ff8a2006-05-23 11:23:49 +02001759 /*
1760 * Account IO completion. bar_rq isn't accounted as a normal
1761 * IO on queueing nor completion. Accounting the containing
1762 * request is enough.
1763 */
1764 if (disk && blk_fs_request(req) && req != &req->q->bar_rq) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001765 unsigned long duration = jiffies - req->start_time;
Jens Axboea3623572005-11-01 09:26:16 +01001766 const int rw = rq_data_dir(req);
Tejun Heoe71bf0d2008-09-03 09:03:02 +02001767 struct hd_struct *part;
Tejun Heoc9959052008-08-25 19:47:21 +09001768 int cpu;
Tejun Heoe71bf0d2008-09-03 09:03:02 +02001769
Tejun Heo074a7ac2008-08-25 19:56:14 +09001770 cpu = part_stat_lock();
Tejun Heoe71bf0d2008-09-03 09:03:02 +02001771 part = disk_map_sector_rcu(disk, req->sector);
Jens Axboea3623572005-11-01 09:26:16 +01001772
Tejun Heo074a7ac2008-08-25 19:56:14 +09001773 part_stat_inc(cpu, part, ios[rw]);
1774 part_stat_add(cpu, part, ticks[rw], duration);
1775 part_round_stats(cpu, part);
1776 part_dec_in_flight(part);
Tejun Heoe71bf0d2008-09-03 09:03:02 +02001777
Tejun Heo074a7ac2008-08-25 19:56:14 +09001778 part_stat_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001779 }
Kiyoshi Uedab8286232007-12-11 17:53:24 -05001780
Linus Torvalds1da177e2005-04-16 15:20:36 -07001781 if (req->end_io)
Tejun Heo8ffdc652006-01-06 09:49:03 +01001782 req->end_io(req, error);
Kiyoshi Uedab8286232007-12-11 17:53:24 -05001783 else {
1784 if (blk_bidi_rq(req))
1785 __blk_put_request(req->next_rq->q, req->next_rq);
1786
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787 __blk_put_request(req->q, req);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001788 }
1789}
1790
Linus Torvalds1da177e2005-04-16 15:20:36 -07001791static inline void __end_request(struct request *rq, int uptodate,
Kiyoshi Ueda9e6e39f2007-12-11 17:41:54 -05001792 unsigned int nr_bytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001793{
Kiyoshi Ueda9e6e39f2007-12-11 17:41:54 -05001794 int error = 0;
1795
1796 if (uptodate <= 0)
1797 error = uptodate ? uptodate : -EIO;
1798
1799 __blk_end_request(rq, error, nr_bytes);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800}
1801
Kiyoshi Ueda3b113132007-12-11 17:41:17 -05001802/**
1803 * blk_rq_bytes - Returns bytes left to complete in the entire request
Randy Dunlap5d87a052008-02-20 09:01:22 +01001804 * @rq: the request being processed
Kiyoshi Ueda3b113132007-12-11 17:41:17 -05001805 **/
1806unsigned int blk_rq_bytes(struct request *rq)
Jens Axboea0cd1282007-09-21 10:41:07 +02001807{
1808 if (blk_fs_request(rq))
1809 return rq->hard_nr_sectors << 9;
1810
1811 return rq->data_len;
1812}
Kiyoshi Ueda3b113132007-12-11 17:41:17 -05001813EXPORT_SYMBOL_GPL(blk_rq_bytes);
1814
1815/**
1816 * blk_rq_cur_bytes - Returns bytes left to complete in the current segment
Randy Dunlap5d87a052008-02-20 09:01:22 +01001817 * @rq: the request being processed
Kiyoshi Ueda3b113132007-12-11 17:41:17 -05001818 **/
1819unsigned int blk_rq_cur_bytes(struct request *rq)
1820{
1821 if (blk_fs_request(rq))
1822 return rq->current_nr_sectors << 9;
1823
1824 if (rq->bio)
1825 return rq->bio->bi_size;
1826
1827 return rq->data_len;
1828}
1829EXPORT_SYMBOL_GPL(blk_rq_cur_bytes);
Jens Axboea0cd1282007-09-21 10:41:07 +02001830
1831/**
1832 * end_queued_request - end all I/O on a queued request
1833 * @rq: the request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02001834 * @uptodate: error value or %0/%1 uptodate flag
Jens Axboea0cd1282007-09-21 10:41:07 +02001835 *
1836 * Description:
1837 * Ends all I/O on a request, and removes it from the block layer queues.
Randy Dunlap710027a2008-08-19 20:13:11 +02001838 * Not suitable for normal I/O completion, unless the driver still has
Jens Axboea0cd1282007-09-21 10:41:07 +02001839 * the request attached to the block layer.
1840 *
1841 **/
1842void end_queued_request(struct request *rq, int uptodate)
1843{
Kiyoshi Ueda9e6e39f2007-12-11 17:41:54 -05001844 __end_request(rq, uptodate, blk_rq_bytes(rq));
Jens Axboea0cd1282007-09-21 10:41:07 +02001845}
1846EXPORT_SYMBOL(end_queued_request);
1847
1848/**
1849 * end_dequeued_request - end all I/O on a dequeued request
1850 * @rq: the request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02001851 * @uptodate: error value or %0/%1 uptodate flag
Jens Axboea0cd1282007-09-21 10:41:07 +02001852 *
1853 * Description:
1854 * Ends all I/O on a request. The request must already have been
1855 * dequeued using blkdev_dequeue_request(), as is normally the case
1856 * for most drivers.
1857 *
1858 **/
1859void end_dequeued_request(struct request *rq, int uptodate)
1860{
Kiyoshi Ueda9e6e39f2007-12-11 17:41:54 -05001861 __end_request(rq, uptodate, blk_rq_bytes(rq));
Jens Axboea0cd1282007-09-21 10:41:07 +02001862}
1863EXPORT_SYMBOL(end_dequeued_request);
1864
1865
1866/**
1867 * end_request - end I/O on the current segment of the request
Randy Dunlap8f731f72007-10-18 23:39:28 -07001868 * @req: the request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02001869 * @uptodate: error value or %0/%1 uptodate flag
Jens Axboea0cd1282007-09-21 10:41:07 +02001870 *
1871 * Description:
1872 * Ends I/O on the current segment of a request. If that is the only
1873 * remaining segment, the request is also completed and freed.
1874 *
Randy Dunlap710027a2008-08-19 20:13:11 +02001875 * This is a remnant of how older block drivers handled I/O completions.
1876 * Modern drivers typically end I/O on the full request in one go, unless
Jens Axboea0cd1282007-09-21 10:41:07 +02001877 * they have a residual value to account for. For that case this function
1878 * isn't really useful, unless the residual just happens to be the
1879 * full current segment. In other words, don't use this function in new
Jens Axboe839e96a2008-09-02 09:25:21 +02001880 * code. Use blk_end_request() or __blk_end_request() to end partial parts
1881 * of a request, or end_dequeued_request() and end_queued_request() to
1882 * completely end IO on a dequeued/queued request.
Jens Axboea0cd1282007-09-21 10:41:07 +02001883 *
1884 **/
1885void end_request(struct request *req, int uptodate)
1886{
Kiyoshi Ueda9e6e39f2007-12-11 17:41:54 -05001887 __end_request(req, uptodate, req->hard_cur_sectors << 9);
Jens Axboea0cd1282007-09-21 10:41:07 +02001888}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001889EXPORT_SYMBOL(end_request);
1890
Kiyoshi Ueda32fab442008-09-18 10:45:09 -04001891static int end_that_request_data(struct request *rq, int error,
1892 unsigned int nr_bytes, unsigned int bidi_bytes)
1893{
1894 if (rq->bio) {
1895 if (__end_that_request_first(rq, error, nr_bytes))
1896 return 1;
1897
1898 /* Bidi request must be completed as a whole */
1899 if (blk_bidi_rq(rq) &&
1900 __end_that_request_first(rq->next_rq, error, bidi_bytes))
1901 return 1;
1902 }
1903
1904 return 0;
1905}
1906
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001907/**
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001908 * blk_end_io - Generic end_io function to complete a request.
1909 * @rq: the request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02001910 * @error: %0 for success, < %0 for error
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05001911 * @nr_bytes: number of bytes to complete @rq
1912 * @bidi_bytes: number of bytes to complete @rq->next_rq
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001913 * @drv_callback: function called between completion of bios in the request
1914 * and completion of the request.
Randy Dunlap710027a2008-08-19 20:13:11 +02001915 * If the callback returns non %0, this helper returns without
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001916 * completion of the request.
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001917 *
1918 * Description:
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05001919 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001920 * If @rq has leftover, sets it up for the next range of segments.
1921 *
1922 * Return:
Randy Dunlap710027a2008-08-19 20:13:11 +02001923 * %0 - we are done with this request
1924 * %1 - this request is not freed yet, it still has pending buffers.
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001925 **/
Jens Axboe22b13212008-01-31 12:36:19 +01001926static int blk_end_io(struct request *rq, int error, unsigned int nr_bytes,
1927 unsigned int bidi_bytes,
1928 int (drv_callback)(struct request *))
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001929{
1930 struct request_queue *q = rq->q;
1931 unsigned long flags = 0UL;
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001932
Kiyoshi Ueda32fab442008-09-18 10:45:09 -04001933 if (end_that_request_data(rq, error, nr_bytes, bidi_bytes))
1934 return 1;
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001935
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001936 /* Special feature for tricky drivers */
1937 if (drv_callback && drv_callback(rq))
1938 return 1;
1939
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001940 add_disk_randomness(rq->rq_disk);
1941
1942 spin_lock_irqsave(q->queue_lock, flags);
Kiyoshi Uedab8286232007-12-11 17:53:24 -05001943 end_that_request_last(rq, error);
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001944 spin_unlock_irqrestore(q->queue_lock, flags);
1945
1946 return 0;
1947}
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001948
1949/**
1950 * blk_end_request - Helper function for drivers to complete the request.
1951 * @rq: the request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02001952 * @error: %0 for success, < %0 for error
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001953 * @nr_bytes: number of bytes to complete
1954 *
1955 * Description:
1956 * Ends I/O on a number of bytes attached to @rq.
1957 * If @rq has leftover, sets it up for the next range of segments.
1958 *
1959 * Return:
Randy Dunlap710027a2008-08-19 20:13:11 +02001960 * %0 - we are done with this request
1961 * %1 - still buffers pending for this request
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001962 **/
Jens Axboe22b13212008-01-31 12:36:19 +01001963int blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001964{
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05001965 return blk_end_io(rq, error, nr_bytes, 0, NULL);
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001966}
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001967EXPORT_SYMBOL_GPL(blk_end_request);
1968
1969/**
1970 * __blk_end_request - Helper function for drivers to complete the request.
1971 * @rq: the request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02001972 * @error: %0 for success, < %0 for error
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001973 * @nr_bytes: number of bytes to complete
1974 *
1975 * Description:
1976 * Must be called with queue lock held unlike blk_end_request().
1977 *
1978 * Return:
Randy Dunlap710027a2008-08-19 20:13:11 +02001979 * %0 - we are done with this request
1980 * %1 - still buffers pending for this request
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001981 **/
Jens Axboe22b13212008-01-31 12:36:19 +01001982int __blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001983{
Jens Axboe60540162008-08-26 13:34:34 +02001984 if (rq->bio && __end_that_request_first(rq, error, nr_bytes))
Jens Axboe051cc392008-08-08 11:06:45 +02001985 return 1;
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001986
1987 add_disk_randomness(rq->rq_disk);
1988
Kiyoshi Uedab8286232007-12-11 17:53:24 -05001989 end_that_request_last(rq, error);
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05001990
1991 return 0;
1992}
1993EXPORT_SYMBOL_GPL(__blk_end_request);
1994
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05001995/**
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05001996 * blk_end_bidi_request - Helper function for drivers to complete bidi request.
1997 * @rq: the bidi request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02001998 * @error: %0 for success, < %0 for error
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05001999 * @nr_bytes: number of bytes to complete @rq
2000 * @bidi_bytes: number of bytes to complete @rq->next_rq
2001 *
2002 * Description:
2003 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2004 *
2005 * Return:
Randy Dunlap710027a2008-08-19 20:13:11 +02002006 * %0 - we are done with this request
2007 * %1 - still buffers pending for this request
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05002008 **/
Jens Axboe22b13212008-01-31 12:36:19 +01002009int blk_end_bidi_request(struct request *rq, int error, unsigned int nr_bytes,
2010 unsigned int bidi_bytes)
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05002011{
2012 return blk_end_io(rq, error, nr_bytes, bidi_bytes, NULL);
2013}
2014EXPORT_SYMBOL_GPL(blk_end_bidi_request);
2015
2016/**
Kiyoshi Ueda32fab442008-09-18 10:45:09 -04002017 * blk_update_request - Special helper function for request stacking drivers
2018 * @rq: the request being processed
2019 * @error: %0 for success, < %0 for error
2020 * @nr_bytes: number of bytes to complete @rq
2021 *
2022 * Description:
2023 * Ends I/O on a number of bytes attached to @rq, but doesn't complete
2024 * the request structure even if @rq doesn't have leftover.
2025 * If @rq has leftover, sets it up for the next range of segments.
2026 *
2027 * This special helper function is only for request stacking drivers
2028 * (e.g. request-based dm) so that they can handle partial completion.
2029 * Actual device drivers should use blk_end_request instead.
2030 */
2031void blk_update_request(struct request *rq, int error, unsigned int nr_bytes)
2032{
2033 if (!end_that_request_data(rq, error, nr_bytes, 0)) {
2034 /*
2035 * These members are not updated in end_that_request_data()
2036 * when all bios are completed.
2037 * Update them so that the request stacking driver can find
2038 * how many bytes remain in the request later.
2039 */
2040 rq->nr_sectors = rq->hard_nr_sectors = 0;
2041 rq->current_nr_sectors = rq->hard_cur_sectors = 0;
2042 }
2043}
2044EXPORT_SYMBOL_GPL(blk_update_request);
2045
2046/**
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002047 * blk_end_request_callback - Special helper function for tricky drivers
2048 * @rq: the request being processed
Randy Dunlap710027a2008-08-19 20:13:11 +02002049 * @error: %0 for success, < %0 for error
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002050 * @nr_bytes: number of bytes to complete
2051 * @drv_callback: function called between completion of bios in the request
2052 * and completion of the request.
Randy Dunlap710027a2008-08-19 20:13:11 +02002053 * If the callback returns non %0, this helper returns without
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002054 * completion of the request.
2055 *
2056 * Description:
2057 * Ends I/O on a number of bytes attached to @rq.
2058 * If @rq has leftover, sets it up for the next range of segments.
2059 *
2060 * This special helper function is used only for existing tricky drivers.
2061 * (e.g. cdrom_newpc_intr() of ide-cd)
2062 * This interface will be removed when such drivers are rewritten.
2063 * Don't use this interface in other places anymore.
2064 *
2065 * Return:
Randy Dunlap710027a2008-08-19 20:13:11 +02002066 * %0 - we are done with this request
2067 * %1 - this request is not freed yet.
2068 * this request still has pending buffers or
2069 * the driver doesn't want to finish this request yet.
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002070 **/
Jens Axboe22b13212008-01-31 12:36:19 +01002071int blk_end_request_callback(struct request *rq, int error,
2072 unsigned int nr_bytes,
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002073 int (drv_callback)(struct request *))
2074{
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05002075 return blk_end_io(rq, error, nr_bytes, 0, drv_callback);
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002076}
2077EXPORT_SYMBOL_GPL(blk_end_request_callback);
2078
Jens Axboe86db1e22008-01-29 14:53:40 +01002079void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
2080 struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081{
David Woodhoused628eae2008-08-09 16:22:17 +01002082 /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw, and
2083 we want BIO_RW_AHEAD (bit 1) to imply REQ_FAILFAST (bit 1). */
Jens Axboe4aff5e22006-08-10 08:44:47 +02002084 rq->cmd_flags |= (bio->bi_rw & 3);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002085
David Woodhousefb2dce82008-08-05 18:01:53 +01002086 if (bio_has_data(bio)) {
2087 rq->nr_phys_segments = bio_phys_segments(q, bio);
David Woodhousefb2dce82008-08-05 18:01:53 +01002088 rq->buffer = bio_data(bio);
2089 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002090 rq->current_nr_sectors = bio_cur_sectors(bio);
2091 rq->hard_cur_sectors = rq->current_nr_sectors;
2092 rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio);
Mike Christie0e75f902006-12-01 10:40:55 +01002093 rq->data_len = bio->bi_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002094
2095 rq->bio = rq->biotail = bio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002096
NeilBrown66846572007-08-16 13:31:28 +02002097 if (bio->bi_bdev)
2098 rq->rq_disk = bio->bi_bdev->bd_disk;
2099}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002100
Jens Axboe18887ad2008-07-28 13:08:45 +02002101int kblockd_schedule_work(struct request_queue *q, struct work_struct *work)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002102{
2103 return queue_work(kblockd_workqueue, work);
2104}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002105EXPORT_SYMBOL(kblockd_schedule_work);
2106
Andrew Morton19a75d82007-05-09 02:33:56 -07002107void kblockd_flush_work(struct work_struct *work)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002108{
Oleg Nesterov28e53bd2007-05-09 02:34:22 -07002109 cancel_work_sync(work);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002110}
Andrew Morton19a75d82007-05-09 02:33:56 -07002111EXPORT_SYMBOL(kblockd_flush_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002112
2113int __init blk_dev_init(void)
2114{
2115 kblockd_workqueue = create_workqueue("kblockd");
2116 if (!kblockd_workqueue)
2117 panic("Failed to create kblockd\n");
2118
2119 request_cachep = kmem_cache_create("blkdev_requests",
Paul Mundt20c2df82007-07-20 10:11:58 +09002120 sizeof(struct request), 0, SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002121
Jens Axboe8324aa92008-01-29 14:51:59 +01002122 blk_requestq_cachep = kmem_cache_create("blkdev_queue",
Jens Axboe165125e2007-07-24 09:28:11 +02002123 sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002124
Linus Torvalds1da177e2005-04-16 15:20:36 -07002125 return 0;
2126}
2127