blob: c973249d68cda01e0c7889ae8708e4da0f9ca4d2 [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 Mortonfaccbd4b2006-12-10 02:19:35 -080028#include <linux/task_io_accounting_ops.h>
Akinobu Mitac17bb492006-12-08 02:39:46 -080029#include <linux/fault-inject.h>
Jens Axboe73c10102011-03-08 13:19:51 +010030#include <linux/list_sort.h>
Tejun Heoe3c78ca2011-10-19 14:32:38 +020031#include <linux/delay.h>
Tejun Heoaaf7c682012-04-19 16:29:22 -070032#include <linux/ratelimit.h>
Li Zefan55782132009-06-09 13:43:05 +080033
34#define CREATE_TRACE_POINTS
35#include <trace/events/block.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070036
Jens Axboe8324aa92008-01-29 14:51:59 +010037#include "blk.h"
Tejun Heo5efd6112012-03-05 13:15:12 -080038#include "blk-cgroup.h"
Jens Axboe8324aa92008-01-29 14:51:59 +010039
Mike Snitzerd07335e2010-11-16 12:52:38 +010040EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
Jun'ichi Nomurab0da3f02009-10-01 21:16:13 +020041EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
Li Zefan55782132009-06-09 13:43:05 +080042EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
NeilBrowncbae8d42012-12-14 20:49:27 +010043EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
Ingo Molnar0bfc2452008-11-26 11:59:56 +010044
Tejun Heoa73f7302011-12-14 00:33:37 +010045DEFINE_IDA(blk_queue_ida);
46
Linus Torvalds1da177e2005-04-16 15:20:36 -070047/*
48 * For the allocated request tables
49 */
Adrian Bunk5ece6c52008-02-18 13:45:51 +010050static struct kmem_cache *request_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070051
52/*
53 * For queue allocation
54 */
Jens Axboe6728cb02008-01-31 13:03:55 +010055struct kmem_cache *blk_requestq_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070056
57/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 * Controlling structure to kblockd
59 */
Jens Axboeff856ba2006-01-09 16:02:34 +010060static struct workqueue_struct *kblockd_workqueue;
Linus Torvalds1da177e2005-04-16 15:20:36 -070061
Jens Axboe26b82562008-01-29 13:54:41 +010062static void drive_stat_acct(struct request *rq, int new_io)
63{
Jens Axboe28f13702008-05-07 10:15:46 +020064 struct hd_struct *part;
Jens Axboe26b82562008-01-29 13:54:41 +010065 int rw = rq_data_dir(rq);
Tejun Heoc9959052008-08-25 19:47:21 +090066 int cpu;
Jens Axboe26b82562008-01-29 13:54:41 +010067
Jens Axboec2553b52009-04-24 08:10:11 +020068 if (!blk_do_io_stat(rq))
Jens Axboe26b82562008-01-29 13:54:41 +010069 return;
70
Tejun Heo074a7ac2008-08-25 19:56:14 +090071 cpu = part_stat_lock();
Tejun Heoc9959052008-08-25 19:47:21 +090072
Jerome Marchand09e099d2011-01-05 16:57:38 +010073 if (!new_io) {
74 part = rq->part;
Tejun Heo074a7ac2008-08-25 19:56:14 +090075 part_stat_inc(cpu, part, merges[rw]);
Jerome Marchand09e099d2011-01-05 16:57:38 +010076 } else {
77 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
Jens Axboe6c23a962011-01-07 08:43:37 +010078 if (!hd_struct_try_get(part)) {
Jerome Marchand09e099d2011-01-05 16:57:38 +010079 /*
80 * The partition is already being removed,
81 * the request will be accounted on the disk only
82 *
83 * We take a reference on disk->part0 although that
84 * partition will never be deleted, so we can treat
85 * it as any other partition.
86 */
87 part = &rq->rq_disk->part0;
Jens Axboe6c23a962011-01-07 08:43:37 +010088 hd_struct_get(part);
Jerome Marchand09e099d2011-01-05 16:57:38 +010089 }
Tejun Heo074a7ac2008-08-25 19:56:14 +090090 part_round_stats(cpu, part);
Nikanth Karthikesan316d3152009-10-06 20:16:55 +020091 part_inc_in_flight(part, rw);
Jerome Marchand09e099d2011-01-05 16:57:38 +010092 rq->part = part;
Jens Axboe26b82562008-01-29 13:54:41 +010093 }
Tejun Heoe71bf0d2008-09-03 09:03:02 +020094
Tejun Heo074a7ac2008-08-25 19:56:14 +090095 part_stat_unlock();
Jens Axboe26b82562008-01-29 13:54:41 +010096}
97
Jens Axboe8324aa92008-01-29 14:51:59 +010098void blk_queue_congestion_threshold(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -070099{
100 int nr;
101
102 nr = q->nr_requests - (q->nr_requests / 8) + 1;
103 if (nr > q->nr_requests)
104 nr = q->nr_requests;
105 q->nr_congestion_on = nr;
106
107 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
108 if (nr < 1)
109 nr = 1;
110 q->nr_congestion_off = nr;
111}
112
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113/**
114 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
115 * @bdev: device
116 *
117 * Locates the passed device's request queue and returns the address of its
118 * backing_dev_info
119 *
120 * Will return NULL if the request queue cannot be located.
121 */
122struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
123{
124 struct backing_dev_info *ret = NULL;
Jens Axboe165125e2007-07-24 09:28:11 +0200125 struct request_queue *q = bdev_get_queue(bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126
127 if (q)
128 ret = &q->backing_dev_info;
129 return ret;
130}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131EXPORT_SYMBOL(blk_get_backing_dev_info);
132
FUJITA Tomonori2a4aa302008-04-29 09:54:36 +0200133void blk_rq_init(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134{
FUJITA Tomonori1afb20f2008-04-25 12:26:28 +0200135 memset(rq, 0, sizeof(*rq));
136
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 INIT_LIST_HEAD(&rq->queuelist);
Jens Axboe242f9dc2008-09-14 05:55:09 -0700138 INIT_LIST_HEAD(&rq->timeout_list);
Jens Axboec7c22e42008-09-13 20:26:01 +0200139 rq->cpu = -1;
Jens Axboe63a71382008-02-08 12:41:03 +0100140 rq->q = q;
Tejun Heoa2dec7b2009-05-07 22:24:44 +0900141 rq->__sector = (sector_t) -1;
Jens Axboe2e662b62006-07-13 11:55:04 +0200142 INIT_HLIST_NODE(&rq->hash);
143 RB_CLEAR_NODE(&rq->rb_node);
FUJITA Tomonorid7e3c322008-04-29 09:54:39 +0200144 rq->cmd = rq->__cmd;
Li Zefane2494e12009-04-02 13:43:26 +0800145 rq->cmd_len = BLK_MAX_CDB;
Jens Axboe63a71382008-02-08 12:41:03 +0100146 rq->tag = -1;
Jens Axboe63a71382008-02-08 12:41:03 +0100147 rq->ref_count = 1;
Tejun Heob243ddc2009-04-23 11:05:18 +0900148 rq->start_time = jiffies;
Divyesh Shah91952912010-04-01 15:01:41 -0700149 set_start_time_ns(rq);
Jerome Marchand09e099d2011-01-05 16:57:38 +0100150 rq->part = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151}
FUJITA Tomonori2a4aa302008-04-29 09:54:36 +0200152EXPORT_SYMBOL(blk_rq_init);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153
NeilBrown5bb23a62007-09-27 12:46:13 +0200154static void req_bio_endio(struct request *rq, struct bio *bio,
155 unsigned int nbytes, int error)
Tejun Heo797e7db2006-01-06 09:51:03 +0100156{
Tejun Heo143a87f2011-01-25 12:43:52 +0100157 if (error)
158 clear_bit(BIO_UPTODATE, &bio->bi_flags);
159 else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
160 error = -EIO;
Tejun Heo797e7db2006-01-06 09:51:03 +0100161
Tejun Heo143a87f2011-01-25 12:43:52 +0100162 if (unlikely(nbytes > bio->bi_size)) {
163 printk(KERN_ERR "%s: want %u bytes done, %u left\n",
164 __func__, nbytes, bio->bi_size);
165 nbytes = bio->bi_size;
NeilBrown5bb23a62007-09-27 12:46:13 +0200166 }
Tejun Heo143a87f2011-01-25 12:43:52 +0100167
168 if (unlikely(rq->cmd_flags & REQ_QUIET))
169 set_bit(BIO_QUIET, &bio->bi_flags);
170
171 bio->bi_size -= nbytes;
172 bio->bi_sector += (nbytes >> 9);
173
174 if (bio_integrity(bio))
175 bio_integrity_advance(bio, nbytes);
176
177 /* don't actually finish bio if it's part of flush sequence */
178 if (bio->bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ))
179 bio_endio(bio, error);
Tejun Heo797e7db2006-01-06 09:51:03 +0100180}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182void blk_dump_rq_flags(struct request *rq, char *msg)
183{
184 int bit;
185
Jens Axboe6728cb02008-01-31 13:03:55 +0100186 printk(KERN_INFO "%s: dev %s: type=%x, flags=%x\n", msg,
Jens Axboe4aff5e22006-08-10 08:44:47 +0200187 rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type,
188 rq->cmd_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189
Tejun Heo83096eb2009-05-07 22:24:39 +0900190 printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n",
191 (unsigned long long)blk_rq_pos(rq),
192 blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
Tejun Heo731ec492009-04-23 11:05:20 +0900193 printk(KERN_INFO " bio %p, biotail %p, buffer %p, len %u\n",
Tejun Heo2e46e8b2009-05-07 22:24:41 +0900194 rq->bio, rq->biotail, rq->buffer, blk_rq_bytes(rq));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195
Christoph Hellwig33659eb2010-08-07 18:17:56 +0200196 if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
Jens Axboe6728cb02008-01-31 13:03:55 +0100197 printk(KERN_INFO " cdb: ");
FUJITA Tomonorid34c87e2008-04-29 14:37:52 +0200198 for (bit = 0; bit < BLK_MAX_CDB; bit++)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199 printk("%02x ", rq->cmd[bit]);
200 printk("\n");
201 }
202}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203EXPORT_SYMBOL(blk_dump_rq_flags);
204
Jens Axboe3cca6dc2011-03-02 11:08:00 -0500205static void blk_delay_work(struct work_struct *work)
Jens Axboe6c5e0c42008-08-01 20:31:32 +0200206{
Jens Axboe3cca6dc2011-03-02 11:08:00 -0500207 struct request_queue *q;
Jens Axboe6c5e0c42008-08-01 20:31:32 +0200208
Jens Axboe3cca6dc2011-03-02 11:08:00 -0500209 q = container_of(work, struct request_queue, delay_work.work);
210 spin_lock_irq(q->queue_lock);
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +0200211 __blk_run_queue(q);
Jens Axboe3cca6dc2011-03-02 11:08:00 -0500212 spin_unlock_irq(q->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214
215/**
Jens Axboe3cca6dc2011-03-02 11:08:00 -0500216 * blk_delay_queue - restart queueing after defined interval
217 * @q: The &struct request_queue in question
218 * @msecs: Delay in msecs
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219 *
220 * Description:
Jens Axboe3cca6dc2011-03-02 11:08:00 -0500221 * Sometimes queueing needs to be postponed for a little while, to allow
222 * resources to come back. This function will make sure that queueing is
Bart Van Assche70460572012-11-28 13:45:56 +0100223 * restarted around the specified time. Queue lock must be held.
Jens Axboe3cca6dc2011-03-02 11:08:00 -0500224 */
225void blk_delay_queue(struct request_queue *q, unsigned long msecs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226{
Bart Van Assche70460572012-11-28 13:45:56 +0100227 if (likely(!blk_queue_dead(q)))
228 queue_delayed_work(kblockd_workqueue, &q->delay_work,
229 msecs_to_jiffies(msecs));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230}
Jens Axboe3cca6dc2011-03-02 11:08:00 -0500231EXPORT_SYMBOL(blk_delay_queue);
Alan D. Brunelle2ad8b1e2007-11-07 14:26:56 -0500232
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233/**
234 * blk_start_queue - restart a previously stopped queue
Jens Axboe165125e2007-07-24 09:28:11 +0200235 * @q: The &struct request_queue in question
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236 *
237 * Description:
238 * blk_start_queue() will clear the stop flag on the queue, and call
239 * the request_fn for the queue if it was in a stopped state when
240 * entered. Also see blk_stop_queue(). Queue lock must be held.
241 **/
Jens Axboe165125e2007-07-24 09:28:11 +0200242void blk_start_queue(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243{
Paolo 'Blaisorblade' Giarrussoa038e252006-06-05 12:09:01 +0200244 WARN_ON(!irqs_disabled());
245
Nick Piggin75ad23b2008-04-29 14:48:33 +0200246 queue_flag_clear(QUEUE_FLAG_STOPPED, q);
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +0200247 __blk_run_queue(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249EXPORT_SYMBOL(blk_start_queue);
250
251/**
252 * blk_stop_queue - stop a queue
Jens Axboe165125e2007-07-24 09:28:11 +0200253 * @q: The &struct request_queue in question
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254 *
255 * Description:
256 * The Linux block layer assumes that a block driver will consume all
257 * entries on the request queue when the request_fn strategy is called.
258 * Often this will not happen, because of hardware limitations (queue
259 * depth settings). If a device driver gets a 'queue full' response,
260 * or if it simply chooses not to queue more I/O at one point, it can
261 * call this function to prevent the request_fn from being called until
262 * the driver has signalled it's ready to go again. This happens by calling
263 * blk_start_queue() to restart queue operations. Queue lock must be held.
264 **/
Jens Axboe165125e2007-07-24 09:28:11 +0200265void blk_stop_queue(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266{
Tejun Heo136b5722012-08-21 13:18:24 -0700267 cancel_delayed_work(&q->delay_work);
Nick Piggin75ad23b2008-04-29 14:48:33 +0200268 queue_flag_set(QUEUE_FLAG_STOPPED, q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269}
270EXPORT_SYMBOL(blk_stop_queue);
271
272/**
273 * blk_sync_queue - cancel any pending callbacks on a queue
274 * @q: the queue
275 *
276 * Description:
277 * The block layer may perform asynchronous callback activity
278 * on a queue, such as calling the unplug function after a timeout.
279 * A block device may call blk_sync_queue to ensure that any
280 * such activity is cancelled, thus allowing it to release resources
Michael Opdenacker59c51592007-05-09 08:57:56 +0200281 * that the callbacks might use. The caller must already have made sure
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282 * that its ->make_request_fn will not re-add plugging prior to calling
283 * this function.
284 *
Vivek Goyalda527772011-03-02 19:05:33 -0500285 * This function does not cancel any asynchronous activity arising
286 * out of elevator or throttling code. That would require elevaotor_exit()
Tejun Heo5efd6112012-03-05 13:15:12 -0800287 * and blkcg_exit_queue() to be called with queue lock initialized.
Vivek Goyalda527772011-03-02 19:05:33 -0500288 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 */
290void blk_sync_queue(struct request_queue *q)
291{
Jens Axboe70ed28b2008-11-19 14:38:39 +0100292 del_timer_sync(&q->timeout);
Jens Axboe3cca6dc2011-03-02 11:08:00 -0500293 cancel_delayed_work_sync(&q->delay_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294}
295EXPORT_SYMBOL(blk_sync_queue);
296
297/**
Bart Van Asschec246e802012-12-06 14:32:01 +0100298 * __blk_run_queue_uncond - run a queue whether or not it has been stopped
299 * @q: The queue to run
300 *
301 * Description:
302 * Invoke request handling on a queue if there are any pending requests.
303 * May be used to restart request handling after a request has completed.
304 * This variant runs the queue whether or not the queue has been
305 * stopped. Must be called with the queue lock held and interrupts
306 * disabled. See also @blk_run_queue.
307 */
308inline void __blk_run_queue_uncond(struct request_queue *q)
309{
310 if (unlikely(blk_queue_dead(q)))
311 return;
312
Bart Van Assche24faf6f2012-11-28 13:46:45 +0100313 /*
314 * Some request_fn implementations, e.g. scsi_request_fn(), unlock
315 * the queue lock internally. As a result multiple threads may be
316 * running such a request function concurrently. Keep track of the
317 * number of active request_fn invocations such that blk_drain_queue()
318 * can wait until all these request_fn calls have finished.
319 */
320 q->request_fn_active++;
Bart Van Asschec246e802012-12-06 14:32:01 +0100321 q->request_fn(q);
Bart Van Assche24faf6f2012-11-28 13:46:45 +0100322 q->request_fn_active--;
Bart Van Asschec246e802012-12-06 14:32:01 +0100323}
324
325/**
Jens Axboe80a4b582008-10-14 09:51:06 +0200326 * __blk_run_queue - run a single device queue
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 * @q: The queue to run
Jens Axboe80a4b582008-10-14 09:51:06 +0200328 *
329 * Description:
330 * See @blk_run_queue. This variant must be called with the queue lock
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +0200331 * held and interrupts disabled.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 */
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +0200333void __blk_run_queue(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334{
Tejun Heoa538cd02009-04-23 11:05:17 +0900335 if (unlikely(blk_queue_stopped(q)))
336 return;
337
Bart Van Asschec246e802012-12-06 14:32:01 +0100338 __blk_run_queue_uncond(q);
Nick Piggin75ad23b2008-04-29 14:48:33 +0200339}
340EXPORT_SYMBOL(__blk_run_queue);
Jens Axboedac07ec2006-05-11 08:20:16 +0200341
Nick Piggin75ad23b2008-04-29 14:48:33 +0200342/**
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +0200343 * blk_run_queue_async - run a single device queue in workqueue context
344 * @q: The queue to run
345 *
346 * Description:
347 * Tells kblockd to perform the equivalent of @blk_run_queue on behalf
Bart Van Assche70460572012-11-28 13:45:56 +0100348 * of us. The caller must hold the queue lock.
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +0200349 */
350void blk_run_queue_async(struct request_queue *q)
351{
Bart Van Assche70460572012-11-28 13:45:56 +0100352 if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q)))
Tejun Heoe7c2f962012-08-21 13:18:24 -0700353 mod_delayed_work(kblockd_workqueue, &q->delay_work, 0);
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +0200354}
Jens Axboec21e6be2011-04-19 13:32:46 +0200355EXPORT_SYMBOL(blk_run_queue_async);
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +0200356
357/**
Nick Piggin75ad23b2008-04-29 14:48:33 +0200358 * blk_run_queue - run a single device queue
359 * @q: The queue to run
Jens Axboe80a4b582008-10-14 09:51:06 +0200360 *
361 * Description:
362 * Invoke request handling on this queue, if it has pending work to do.
Tejun Heoa7f55792009-04-23 11:05:17 +0900363 * May be used to restart queueing when a request has completed.
Nick Piggin75ad23b2008-04-29 14:48:33 +0200364 */
365void blk_run_queue(struct request_queue *q)
366{
367 unsigned long flags;
368
369 spin_lock_irqsave(q->queue_lock, flags);
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +0200370 __blk_run_queue(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 spin_unlock_irqrestore(q->queue_lock, flags);
372}
373EXPORT_SYMBOL(blk_run_queue);
374
Jens Axboe165125e2007-07-24 09:28:11 +0200375void blk_put_queue(struct request_queue *q)
Al Viro483f4af2006-03-18 18:34:37 -0500376{
377 kobject_put(&q->kobj);
378}
Jens Axboed86e0e82011-05-27 07:44:43 +0200379EXPORT_SYMBOL(blk_put_queue);
Al Viro483f4af2006-03-18 18:34:37 -0500380
Tejun Heoe3c78ca2011-10-19 14:32:38 +0200381/**
Bart Van Assche807592a2012-11-28 13:43:38 +0100382 * __blk_drain_queue - drain requests from request_queue
Tejun Heoe3c78ca2011-10-19 14:32:38 +0200383 * @q: queue to drain
Tejun Heoc9a929d2011-10-19 14:42:16 +0200384 * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
Tejun Heoe3c78ca2011-10-19 14:32:38 +0200385 *
Tejun Heoc9a929d2011-10-19 14:42:16 +0200386 * Drain requests from @q. If @drain_all is set, all requests are drained.
387 * If not, only ELVPRIV requests are drained. The caller is responsible
388 * for ensuring that no new requests which need to be drained are queued.
Tejun Heoe3c78ca2011-10-19 14:32:38 +0200389 */
Bart Van Assche807592a2012-11-28 13:43:38 +0100390static void __blk_drain_queue(struct request_queue *q, bool drain_all)
391 __releases(q->queue_lock)
392 __acquires(q->queue_lock)
Tejun Heoe3c78ca2011-10-19 14:32:38 +0200393{
Asias He458f27a2012-06-15 08:45:25 +0200394 int i;
395
Bart Van Assche807592a2012-11-28 13:43:38 +0100396 lockdep_assert_held(q->queue_lock);
397
Tejun Heoe3c78ca2011-10-19 14:32:38 +0200398 while (true) {
Tejun Heo481a7d62011-12-14 00:33:37 +0100399 bool drain = false;
Tejun Heoe3c78ca2011-10-19 14:32:38 +0200400
Tejun Heob855b042012-03-06 21:24:55 +0100401 /*
402 * The caller might be trying to drain @q before its
403 * elevator is initialized.
404 */
405 if (q->elevator)
406 elv_drain_elevator(q);
407
Tejun Heo5efd6112012-03-05 13:15:12 -0800408 blkcg_drain_queue(q);
Tejun Heoe3c78ca2011-10-19 14:32:38 +0200409
Tejun Heo4eabc942011-12-15 20:03:04 +0100410 /*
411 * This function might be called on a queue which failed
Tejun Heob855b042012-03-06 21:24:55 +0100412 * driver init after queue creation or is not yet fully
413 * active yet. Some drivers (e.g. fd and loop) get unhappy
414 * in such cases. Kick queue iff dispatch queue has
415 * something on it and @q has request_fn set.
Tejun Heo4eabc942011-12-15 20:03:04 +0100416 */
Tejun Heob855b042012-03-06 21:24:55 +0100417 if (!list_empty(&q->queue_head) && q->request_fn)
Tejun Heo4eabc942011-12-15 20:03:04 +0100418 __blk_run_queue(q);
Tejun Heoc9a929d2011-10-19 14:42:16 +0200419
Tejun Heo8a5ecdd2012-06-04 20:40:58 -0700420 drain |= q->nr_rqs_elvpriv;
Bart Van Assche24faf6f2012-11-28 13:46:45 +0100421 drain |= q->request_fn_active;
Tejun Heo481a7d62011-12-14 00:33:37 +0100422
423 /*
424 * Unfortunately, requests are queued at and tracked from
425 * multiple places and there's no single counter which can
426 * be drained. Check all the queues and counters.
427 */
428 if (drain_all) {
429 drain |= !list_empty(&q->queue_head);
430 for (i = 0; i < 2; i++) {
Tejun Heo8a5ecdd2012-06-04 20:40:58 -0700431 drain |= q->nr_rqs[i];
Tejun Heo481a7d62011-12-14 00:33:37 +0100432 drain |= q->in_flight[i];
433 drain |= !list_empty(&q->flush_queue[i]);
434 }
435 }
Tejun Heoe3c78ca2011-10-19 14:32:38 +0200436
Tejun Heo481a7d62011-12-14 00:33:37 +0100437 if (!drain)
Tejun Heoe3c78ca2011-10-19 14:32:38 +0200438 break;
Bart Van Assche807592a2012-11-28 13:43:38 +0100439
440 spin_unlock_irq(q->queue_lock);
441
Tejun Heoe3c78ca2011-10-19 14:32:38 +0200442 msleep(10);
Bart Van Assche807592a2012-11-28 13:43:38 +0100443
444 spin_lock_irq(q->queue_lock);
Tejun Heoe3c78ca2011-10-19 14:32:38 +0200445 }
Asias He458f27a2012-06-15 08:45:25 +0200446
447 /*
448 * With queue marked dead, any woken up waiter will fail the
449 * allocation path, so the wakeup chaining is lost and we're
450 * left with hung waiters. We need to wake up those waiters.
451 */
452 if (q->request_fn) {
Tejun Heoa0516612012-06-26 15:05:44 -0700453 struct request_list *rl;
454
Tejun Heoa0516612012-06-26 15:05:44 -0700455 blk_queue_for_each_rl(rl, q)
456 for (i = 0; i < ARRAY_SIZE(rl->wait); i++)
457 wake_up_all(&rl->wait[i]);
Asias He458f27a2012-06-15 08:45:25 +0200458 }
Tejun Heoe3c78ca2011-10-19 14:32:38 +0200459}
460
Tejun Heoc9a929d2011-10-19 14:42:16 +0200461/**
Tejun Heod7325802012-03-05 13:14:58 -0800462 * blk_queue_bypass_start - enter queue bypass mode
463 * @q: queue of interest
464 *
465 * In bypass mode, only the dispatch FIFO queue of @q is used. This
466 * function makes @q enter bypass mode and drains all requests which were
Tejun Heo6ecf23a2012-03-05 13:14:59 -0800467 * throttled or issued before. On return, it's guaranteed that no request
Tejun Heo80fd9972012-04-13 14:50:53 -0700468 * is being throttled or has ELVPRIV set and blk_queue_bypass() %true
469 * inside queue or RCU read lock.
Tejun Heod7325802012-03-05 13:14:58 -0800470 */
471void blk_queue_bypass_start(struct request_queue *q)
472{
Tejun Heob82d4b12012-04-13 13:11:31 -0700473 bool drain;
474
Tejun Heod7325802012-03-05 13:14:58 -0800475 spin_lock_irq(q->queue_lock);
Tejun Heob82d4b12012-04-13 13:11:31 -0700476 drain = !q->bypass_depth++;
Tejun Heod7325802012-03-05 13:14:58 -0800477 queue_flag_set(QUEUE_FLAG_BYPASS, q);
478 spin_unlock_irq(q->queue_lock);
479
Tejun Heob82d4b12012-04-13 13:11:31 -0700480 if (drain) {
Bart Van Assche807592a2012-11-28 13:43:38 +0100481 spin_lock_irq(q->queue_lock);
482 __blk_drain_queue(q, false);
483 spin_unlock_irq(q->queue_lock);
484
Tejun Heob82d4b12012-04-13 13:11:31 -0700485 /* ensure blk_queue_bypass() is %true inside RCU read lock */
486 synchronize_rcu();
487 }
Tejun Heod7325802012-03-05 13:14:58 -0800488}
489EXPORT_SYMBOL_GPL(blk_queue_bypass_start);
490
491/**
492 * blk_queue_bypass_end - leave queue bypass mode
493 * @q: queue of interest
494 *
495 * Leave bypass mode and restore the normal queueing behavior.
496 */
497void blk_queue_bypass_end(struct request_queue *q)
498{
499 spin_lock_irq(q->queue_lock);
500 if (!--q->bypass_depth)
501 queue_flag_clear(QUEUE_FLAG_BYPASS, q);
502 WARN_ON_ONCE(q->bypass_depth < 0);
503 spin_unlock_irq(q->queue_lock);
504}
505EXPORT_SYMBOL_GPL(blk_queue_bypass_end);
506
507/**
Tejun Heoc9a929d2011-10-19 14:42:16 +0200508 * blk_cleanup_queue - shutdown a request queue
509 * @q: request queue to shutdown
510 *
Bart Van Asschec246e802012-12-06 14:32:01 +0100511 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
512 * put it. All future requests will be failed immediately with -ENODEV.
Vivek Goyalc94a96a2011-03-02 19:04:42 -0500513 */
Jens Axboe6728cb02008-01-31 13:03:55 +0100514void blk_cleanup_queue(struct request_queue *q)
Al Viro483f4af2006-03-18 18:34:37 -0500515{
Tejun Heoc9a929d2011-10-19 14:42:16 +0200516 spinlock_t *lock = q->queue_lock;
Jens Axboee3335de2008-09-18 09:22:54 -0700517
Bart Van Assche3f3299d2012-11-28 13:42:38 +0100518 /* mark @q DYING, no new request or merges will be allowed afterwards */
Al Viro483f4af2006-03-18 18:34:37 -0500519 mutex_lock(&q->sysfs_lock);
Bart Van Assche3f3299d2012-11-28 13:42:38 +0100520 queue_flag_set_unlocked(QUEUE_FLAG_DYING, q);
Tejun Heoc9a929d2011-10-19 14:42:16 +0200521 spin_lock_irq(lock);
Tejun Heo6ecf23a2012-03-05 13:14:59 -0800522
Tejun Heo80fd9972012-04-13 14:50:53 -0700523 /*
Bart Van Assche3f3299d2012-11-28 13:42:38 +0100524 * A dying queue is permanently in bypass mode till released. Note
Tejun Heo80fd9972012-04-13 14:50:53 -0700525 * that, unlike blk_queue_bypass_start(), we aren't performing
526 * synchronize_rcu() after entering bypass mode to avoid the delay
527 * as some drivers create and destroy a lot of queues while
528 * probing. This is still safe because blk_release_queue() will be
529 * called only after the queue refcnt drops to zero and nothing,
530 * RCU or not, would be traversing the queue by then.
531 */
Tejun Heo6ecf23a2012-03-05 13:14:59 -0800532 q->bypass_depth++;
533 queue_flag_set(QUEUE_FLAG_BYPASS, q);
534
Tejun Heoc9a929d2011-10-19 14:42:16 +0200535 queue_flag_set(QUEUE_FLAG_NOMERGES, q);
536 queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
Bart Van Assche3f3299d2012-11-28 13:42:38 +0100537 queue_flag_set(QUEUE_FLAG_DYING, q);
Tejun Heoc9a929d2011-10-19 14:42:16 +0200538 spin_unlock_irq(lock);
539 mutex_unlock(&q->sysfs_lock);
540
Bart Van Asschec246e802012-12-06 14:32:01 +0100541 /*
542 * Drain all requests queued before DYING marking. Set DEAD flag to
543 * prevent that q->request_fn() gets invoked after draining finished.
544 */
Bart Van Assche807592a2012-11-28 13:43:38 +0100545 spin_lock_irq(lock);
546 __blk_drain_queue(q, true);
Bart Van Asschec246e802012-12-06 14:32:01 +0100547 queue_flag_set(QUEUE_FLAG_DEAD, q);
Bart Van Assche807592a2012-11-28 13:43:38 +0100548 spin_unlock_irq(lock);
Tejun Heoc9a929d2011-10-19 14:42:16 +0200549
550 /* @q won't process any more request, flush async actions */
551 del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer);
552 blk_sync_queue(q);
553
Asias He5e5cfac2012-05-24 23:28:52 +0800554 spin_lock_irq(lock);
555 if (q->queue_lock != &q->__queue_lock)
556 q->queue_lock = &q->__queue_lock;
557 spin_unlock_irq(lock);
558
Tejun Heoc9a929d2011-10-19 14:42:16 +0200559 /* @q is and will stay empty, shutdown and put */
Al Viro483f4af2006-03-18 18:34:37 -0500560 blk_put_queue(q);
561}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562EXPORT_SYMBOL(blk_cleanup_queue);
563
Tejun Heo5b788ce2012-06-04 20:40:59 -0700564int blk_init_rl(struct request_list *rl, struct request_queue *q,
565 gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566{
Mike Snitzer1abec4f2010-05-25 13:15:15 -0400567 if (unlikely(rl->rq_pool))
568 return 0;
569
Tejun Heo5b788ce2012-06-04 20:40:59 -0700570 rl->q = q;
Jens Axboe1faa16d2009-04-06 14:48:01 +0200571 rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
572 rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
Jens Axboe1faa16d2009-04-06 14:48:01 +0200573 init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
574 init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575
Christoph Lameter19460892005-06-23 00:08:19 -0700576 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
Tejun Heoa91a5ac2012-06-04 20:40:53 -0700577 mempool_free_slab, request_cachep,
Tejun Heo5b788ce2012-06-04 20:40:59 -0700578 gfp_mask, q->node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579 if (!rl->rq_pool)
580 return -ENOMEM;
581
582 return 0;
583}
584
Tejun Heo5b788ce2012-06-04 20:40:59 -0700585void blk_exit_rl(struct request_list *rl)
586{
587 if (rl->rq_pool)
588 mempool_destroy(rl->rq_pool);
589}
590
Jens Axboe165125e2007-07-24 09:28:11 +0200591struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592{
Ezequiel Garciac304a512012-11-10 10:39:44 +0100593 return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE);
Christoph Lameter19460892005-06-23 00:08:19 -0700594}
595EXPORT_SYMBOL(blk_alloc_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596
Jens Axboe165125e2007-07-24 09:28:11 +0200597struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
Christoph Lameter19460892005-06-23 00:08:19 -0700598{
Jens Axboe165125e2007-07-24 09:28:11 +0200599 struct request_queue *q;
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700600 int err;
Christoph Lameter19460892005-06-23 00:08:19 -0700601
Jens Axboe8324aa92008-01-29 14:51:59 +0100602 q = kmem_cache_alloc_node(blk_requestq_cachep,
Christoph Lameter94f60302007-07-17 04:03:29 -0700603 gfp_mask | __GFP_ZERO, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700604 if (!q)
605 return NULL;
606
Dan Carpenter00380a42012-03-23 09:58:54 +0100607 q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask);
Tejun Heoa73f7302011-12-14 00:33:37 +0100608 if (q->id < 0)
609 goto fail_q;
610
Jens Axboe0989a022009-06-12 14:42:56 +0200611 q->backing_dev_info.ra_pages =
612 (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
613 q->backing_dev_info.state = 0;
614 q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
Jens Axboed9938312009-06-12 14:45:52 +0200615 q->backing_dev_info.name = "block";
Mike Snitzer51514122011-11-23 10:59:13 +0100616 q->node = node_id;
Jens Axboe0989a022009-06-12 14:42:56 +0200617
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700618 err = bdi_init(&q->backing_dev_info);
Tejun Heoa73f7302011-12-14 00:33:37 +0100619 if (err)
620 goto fail_id;
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700621
Matthew Garrett31373d02010-04-06 14:25:14 +0200622 setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
623 laptop_mode_timer_fn, (unsigned long) q);
Jens Axboe242f9dc2008-09-14 05:55:09 -0700624 setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
Tejun Heob855b042012-03-06 21:24:55 +0100625 INIT_LIST_HEAD(&q->queue_head);
Jens Axboe242f9dc2008-09-14 05:55:09 -0700626 INIT_LIST_HEAD(&q->timeout_list);
Tejun Heoa612fdd2011-12-14 00:33:41 +0100627 INIT_LIST_HEAD(&q->icq_list);
Tejun Heo4eef3042012-03-05 13:15:18 -0800628#ifdef CONFIG_BLK_CGROUP
Tejun Heoe8989fa2012-03-05 13:15:20 -0800629 INIT_LIST_HEAD(&q->blkg_list);
Tejun Heo4eef3042012-03-05 13:15:18 -0800630#endif
Tejun Heoae1b1532011-01-25 12:43:54 +0100631 INIT_LIST_HEAD(&q->flush_queue[0]);
632 INIT_LIST_HEAD(&q->flush_queue[1]);
633 INIT_LIST_HEAD(&q->flush_data_in_flight);
Jens Axboe3cca6dc2011-03-02 11:08:00 -0500634 INIT_DELAYED_WORK(&q->delay_work, blk_delay_work);
Al Viro483f4af2006-03-18 18:34:37 -0500635
Jens Axboe8324aa92008-01-29 14:51:59 +0100636 kobject_init(&q->kobj, &blk_queue_ktype);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637
Al Viro483f4af2006-03-18 18:34:37 -0500638 mutex_init(&q->sysfs_lock);
Neil Browne7e72bf2008-05-14 16:05:54 -0700639 spin_lock_init(&q->__queue_lock);
Al Viro483f4af2006-03-18 18:34:37 -0500640
Vivek Goyalc94a96a2011-03-02 19:04:42 -0500641 /*
642 * By default initialize queue_lock to internal lock and driver can
643 * override it later if need be.
644 */
645 q->queue_lock = &q->__queue_lock;
646
Tejun Heob82d4b12012-04-13 13:11:31 -0700647 /*
648 * A queue starts its life with bypass turned on to avoid
649 * unnecessary bypass on/off overhead and nasty surprises during
Tejun Heo749fefe2012-09-20 14:08:52 -0700650 * init. The initial bypass will be finished when the queue is
651 * registered by blk_register_queue().
Tejun Heob82d4b12012-04-13 13:11:31 -0700652 */
653 q->bypass_depth = 1;
654 __set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags);
655
Tejun Heo5efd6112012-03-05 13:15:12 -0800656 if (blkcg_init_queue(q))
Tejun Heof51b8022012-03-05 13:15:05 -0800657 goto fail_id;
658
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659 return q;
Tejun Heoa73f7302011-12-14 00:33:37 +0100660
661fail_id:
662 ida_simple_remove(&blk_queue_ida, q->id);
663fail_q:
664 kmem_cache_free(blk_requestq_cachep, q);
665 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666}
Christoph Lameter19460892005-06-23 00:08:19 -0700667EXPORT_SYMBOL(blk_alloc_queue_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668
669/**
670 * blk_init_queue - prepare a request queue for use with a block device
671 * @rfn: The function to be called to process requests that have been
672 * placed on the queue.
673 * @lock: Request queue spin lock
674 *
675 * Description:
676 * If a block device wishes to use the standard request handling procedures,
677 * which sorts requests and coalesces adjacent requests, then it must
678 * call blk_init_queue(). The function @rfn will be called when there
679 * are requests on the queue that need to be processed. If the device
680 * supports plugging, then @rfn may not be called immediately when requests
681 * are available on the queue, but may be called at some time later instead.
682 * Plugged queues are generally unplugged when a buffer belonging to one
683 * of the requests on the queue is needed, or due to memory pressure.
684 *
685 * @rfn is not required, or even expected, to remove all requests off the
686 * queue, but only as many as it can handle at a time. If it does leave
687 * requests on the queue, it is responsible for arranging that the requests
688 * get dealt with eventually.
689 *
690 * The queue spin lock must be held while manipulating the requests on the
Paolo 'Blaisorblade' Giarrussoa038e252006-06-05 12:09:01 +0200691 * request queue; this lock will be taken also from interrupt context, so irq
692 * disabling is needed for it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 *
Randy Dunlap710027a2008-08-19 20:13:11 +0200694 * Function returns a pointer to the initialized request queue, or %NULL if
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695 * it didn't succeed.
696 *
697 * Note:
698 * blk_init_queue() must be paired with a blk_cleanup_queue() call
699 * when the block device is deactivated (such as at module unload).
700 **/
Christoph Lameter19460892005-06-23 00:08:19 -0700701
Jens Axboe165125e2007-07-24 09:28:11 +0200702struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703{
Ezequiel Garciac304a512012-11-10 10:39:44 +0100704 return blk_init_queue_node(rfn, lock, NUMA_NO_NODE);
Christoph Lameter19460892005-06-23 00:08:19 -0700705}
706EXPORT_SYMBOL(blk_init_queue);
707
Jens Axboe165125e2007-07-24 09:28:11 +0200708struct request_queue *
Christoph Lameter19460892005-06-23 00:08:19 -0700709blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
710{
Mike Snitzerc86d1b82010-06-03 11:34:52 -0600711 struct request_queue *uninit_q, *q;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700712
Mike Snitzerc86d1b82010-06-03 11:34:52 -0600713 uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id);
714 if (!uninit_q)
715 return NULL;
716
Mike Snitzer51514122011-11-23 10:59:13 +0100717 q = blk_init_allocated_queue(uninit_q, rfn, lock);
Mike Snitzerc86d1b82010-06-03 11:34:52 -0600718 if (!q)
719 blk_cleanup_queue(uninit_q);
720
721 return q;
Mike Snitzer01effb02010-05-11 08:57:42 +0200722}
723EXPORT_SYMBOL(blk_init_queue_node);
724
725struct request_queue *
726blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
727 spinlock_t *lock)
728{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 if (!q)
730 return NULL;
731
Tejun Heoa0516612012-06-26 15:05:44 -0700732 if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))
Al Viro8669aaf2006-03-18 13:50:00 -0500733 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734
735 q->request_fn = rfn;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700736 q->prep_rq_fn = NULL;
James Bottomley28018c22010-07-01 19:49:17 +0900737 q->unprep_rq_fn = NULL;
Tejun Heo60ea8222012-09-20 14:09:30 -0700738 q->queue_flags |= QUEUE_FLAG_DEFAULT;
Vivek Goyalc94a96a2011-03-02 19:04:42 -0500739
740 /* Override internal queue lock with supplied lock pointer */
741 if (lock)
742 q->queue_lock = lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743
Jens Axboef3b144a2009-03-06 08:48:33 +0100744 /*
745 * This also sets hw/phys segments, boundary and size
746 */
Jens Axboec20e8de2011-09-12 12:03:37 +0200747 blk_queue_make_request(q, blk_queue_bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748
Alan Stern44ec9542007-02-20 11:01:57 -0500749 q->sg_reserved_size = INT_MAX;
750
Tejun Heob82d4b12012-04-13 13:11:31 -0700751 /* init elevator */
752 if (elevator_init(q, NULL))
753 return NULL;
Tejun Heob82d4b12012-04-13 13:11:31 -0700754 return q;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755}
Mike Snitzer51514122011-11-23 10:59:13 +0100756EXPORT_SYMBOL(blk_init_allocated_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757
Tejun Heo09ac46c2011-12-14 00:33:38 +0100758bool blk_get_queue(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759{
Bart Van Assche3f3299d2012-11-28 13:42:38 +0100760 if (likely(!blk_queue_dying(q))) {
Tejun Heo09ac46c2011-12-14 00:33:38 +0100761 __blk_get_queue(q);
762 return true;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763 }
764
Tejun Heo09ac46c2011-12-14 00:33:38 +0100765 return false;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766}
Jens Axboed86e0e82011-05-27 07:44:43 +0200767EXPORT_SYMBOL(blk_get_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768
Tejun Heo5b788ce2012-06-04 20:40:59 -0700769static inline void blk_free_request(struct request_list *rl, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770{
Tejun Heof1f8cc92011-12-14 00:33:42 +0100771 if (rq->cmd_flags & REQ_ELVPRIV) {
Tejun Heo5b788ce2012-06-04 20:40:59 -0700772 elv_put_request(rl->q, rq);
Tejun Heof1f8cc92011-12-14 00:33:42 +0100773 if (rq->elv.icq)
Tejun Heo11a31222012-02-07 07:51:30 +0100774 put_io_context(rq->elv.icq->ioc);
Tejun Heof1f8cc92011-12-14 00:33:42 +0100775 }
776
Tejun Heo5b788ce2012-06-04 20:40:59 -0700777 mempool_free(rq, rl->rq_pool);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778}
779
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780/*
781 * ioc_batching returns true if the ioc is a valid batching request and
782 * should be given priority access to a request.
783 */
Jens Axboe165125e2007-07-24 09:28:11 +0200784static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700785{
786 if (!ioc)
787 return 0;
788
789 /*
790 * Make sure the process is able to allocate at least 1 request
791 * even if the batch times out, otherwise we could theoretically
792 * lose wakeups.
793 */
794 return ioc->nr_batch_requests == q->nr_batching ||
795 (ioc->nr_batch_requests > 0
796 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
797}
798
799/*
800 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
801 * will cause the process to be a "batcher" on all queues in the system. This
802 * is the behaviour we want though - once it gets a wakeup it should be given
803 * a nice run.
804 */
Jens Axboe165125e2007-07-24 09:28:11 +0200805static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806{
807 if (!ioc || ioc_batching(q, ioc))
808 return;
809
810 ioc->nr_batch_requests = q->nr_batching;
811 ioc->last_waited = jiffies;
812}
813
Tejun Heo5b788ce2012-06-04 20:40:59 -0700814static void __freed_request(struct request_list *rl, int sync)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815{
Tejun Heo5b788ce2012-06-04 20:40:59 -0700816 struct request_queue *q = rl->q;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700817
Tejun Heoa0516612012-06-26 15:05:44 -0700818 /*
819 * bdi isn't aware of blkcg yet. As all async IOs end up root
820 * blkcg anyway, just use root blkcg state.
821 */
822 if (rl == &q->root_rl &&
823 rl->count[sync] < queue_congestion_off_threshold(q))
Jens Axboe1faa16d2009-04-06 14:48:01 +0200824 blk_clear_queue_congested(q, sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700825
Jens Axboe1faa16d2009-04-06 14:48:01 +0200826 if (rl->count[sync] + 1 <= q->nr_requests) {
827 if (waitqueue_active(&rl->wait[sync]))
828 wake_up(&rl->wait[sync]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700829
Tejun Heo5b788ce2012-06-04 20:40:59 -0700830 blk_clear_rl_full(rl, sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831 }
832}
833
834/*
835 * A request has just been released. Account for it, update the full and
836 * congestion status, wake up any waiters. Called under q->queue_lock.
837 */
Tejun Heo5b788ce2012-06-04 20:40:59 -0700838static void freed_request(struct request_list *rl, unsigned int flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700839{
Tejun Heo5b788ce2012-06-04 20:40:59 -0700840 struct request_queue *q = rl->q;
Tejun Heo75eb6c32011-10-19 14:31:22 +0200841 int sync = rw_is_sync(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842
Tejun Heo8a5ecdd2012-06-04 20:40:58 -0700843 q->nr_rqs[sync]--;
Jens Axboe1faa16d2009-04-06 14:48:01 +0200844 rl->count[sync]--;
Tejun Heo75eb6c32011-10-19 14:31:22 +0200845 if (flags & REQ_ELVPRIV)
Tejun Heo8a5ecdd2012-06-04 20:40:58 -0700846 q->nr_rqs_elvpriv--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700847
Tejun Heo5b788ce2012-06-04 20:40:59 -0700848 __freed_request(rl, sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700849
Jens Axboe1faa16d2009-04-06 14:48:01 +0200850 if (unlikely(rl->starved[sync ^ 1]))
Tejun Heo5b788ce2012-06-04 20:40:59 -0700851 __freed_request(rl, sync ^ 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700852}
853
Linus Torvalds1da177e2005-04-16 15:20:36 -0700854/*
Mike Snitzer9d5a4e92011-02-11 11:05:46 +0100855 * Determine if elevator data should be initialized when allocating the
856 * request associated with @bio.
857 */
858static bool blk_rq_should_init_elevator(struct bio *bio)
859{
860 if (!bio)
861 return true;
862
863 /*
864 * Flush requests do not use the elevator so skip initialization.
865 * This allows a request to share the flush and elevator data.
866 */
867 if (bio->bi_rw & (REQ_FLUSH | REQ_FUA))
868 return false;
869
870 return true;
871}
872
Tejun Heoda8303c2011-10-19 14:33:05 +0200873/**
Tejun Heo852c7882012-03-05 13:15:27 -0800874 * rq_ioc - determine io_context for request allocation
875 * @bio: request being allocated is for this bio (can be %NULL)
876 *
877 * Determine io_context to use for request allocation for @bio. May return
878 * %NULL if %current->io_context doesn't exist.
879 */
880static struct io_context *rq_ioc(struct bio *bio)
881{
882#ifdef CONFIG_BLK_CGROUP
883 if (bio && bio->bi_ioc)
884 return bio->bi_ioc;
885#endif
886 return current->io_context;
887}
888
889/**
Tejun Heoa06e05e2012-06-04 20:40:55 -0700890 * __get_request - get a free request
Tejun Heo5b788ce2012-06-04 20:40:59 -0700891 * @rl: request list to allocate from
Tejun Heoda8303c2011-10-19 14:33:05 +0200892 * @rw_flags: RW and SYNC flags
893 * @bio: bio to allocate request for (can be %NULL)
894 * @gfp_mask: allocation mask
895 *
896 * Get a free request from @q. This function may fail under memory
897 * pressure or if @q is dead.
898 *
899 * Must be callled with @q->queue_lock held and,
900 * Returns %NULL on failure, with @q->queue_lock held.
901 * Returns !%NULL on success, with @q->queue_lock *not held*.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700902 */
Tejun Heo5b788ce2012-06-04 20:40:59 -0700903static struct request *__get_request(struct request_list *rl, int rw_flags,
Tejun Heoa06e05e2012-06-04 20:40:55 -0700904 struct bio *bio, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700905{
Tejun Heo5b788ce2012-06-04 20:40:59 -0700906 struct request_queue *q = rl->q;
Tejun Heob6792812012-03-05 13:15:23 -0800907 struct request *rq;
Tejun Heo7f4b35d2012-06-04 20:40:56 -0700908 struct elevator_type *et = q->elevator->type;
909 struct io_context *ioc = rq_ioc(bio);
Tejun Heof1f8cc92011-12-14 00:33:42 +0100910 struct io_cq *icq = NULL;
Jens Axboe1faa16d2009-04-06 14:48:01 +0200911 const bool is_sync = rw_is_sync(rw_flags) != 0;
Tejun Heo75eb6c32011-10-19 14:31:22 +0200912 int may_queue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913
Bart Van Assche3f3299d2012-11-28 13:42:38 +0100914 if (unlikely(blk_queue_dying(q)))
Tejun Heoda8303c2011-10-19 14:33:05 +0200915 return NULL;
916
Jens Axboe7749a8d2006-12-13 13:02:26 +0100917 may_queue = elv_may_queue(q, rw_flags);
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100918 if (may_queue == ELV_MQUEUE_NO)
919 goto rq_starved;
920
Jens Axboe1faa16d2009-04-06 14:48:01 +0200921 if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
922 if (rl->count[is_sync]+1 >= q->nr_requests) {
Tejun Heof2dbd762011-12-14 00:33:40 +0100923 /*
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100924 * The queue will fill after this allocation, so set
925 * it as full, and mark this process as "batching".
926 * This process will be allowed to complete a batch of
927 * requests, others will be blocked.
928 */
Tejun Heo5b788ce2012-06-04 20:40:59 -0700929 if (!blk_rl_full(rl, is_sync)) {
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100930 ioc_set_batching(q, ioc);
Tejun Heo5b788ce2012-06-04 20:40:59 -0700931 blk_set_rl_full(rl, is_sync);
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100932 } else {
933 if (may_queue != ELV_MQUEUE_MUST
934 && !ioc_batching(q, ioc)) {
935 /*
936 * The queue is full and the allocating
937 * process is not a "batcher", and not
938 * exempted by the IO scheduler
939 */
Tejun Heob6792812012-03-05 13:15:23 -0800940 return NULL;
Jens Axboe88ee5ef2005-11-12 11:09:12 +0100941 }
942 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700943 }
Tejun Heoa0516612012-06-26 15:05:44 -0700944 /*
945 * bdi isn't aware of blkcg yet. As all async IOs end up
946 * root blkcg anyway, just use root blkcg state.
947 */
948 if (rl == &q->root_rl)
949 blk_set_queue_congested(q, is_sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700950 }
951
Jens Axboe082cf692005-06-28 16:35:11 +0200952 /*
953 * Only allow batching queuers to allocate up to 50% over the defined
954 * limit of requests, otherwise we could have thousands of requests
955 * allocated with any setting of ->nr_requests
956 */
Jens Axboe1faa16d2009-04-06 14:48:01 +0200957 if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
Tejun Heob6792812012-03-05 13:15:23 -0800958 return NULL;
Hugh Dickinsfd782a42005-06-29 15:15:40 +0100959
Tejun Heo8a5ecdd2012-06-04 20:40:58 -0700960 q->nr_rqs[is_sync]++;
Jens Axboe1faa16d2009-04-06 14:48:01 +0200961 rl->count[is_sync]++;
962 rl->starved[is_sync] = 0;
Tejun Heocb98fc82005-10-28 08:29:39 +0200963
Tejun Heof1f8cc92011-12-14 00:33:42 +0100964 /*
965 * Decide whether the new request will be managed by elevator. If
966 * so, mark @rw_flags and increment elvpriv. Non-zero elvpriv will
967 * prevent the current elevator from being destroyed until the new
968 * request is freed. This guarantees icq's won't be destroyed and
969 * makes creating new ones safe.
970 *
971 * Also, lookup icq while holding queue_lock. If it doesn't exist,
972 * it will be created after releasing queue_lock.
973 */
Tejun Heod7325802012-03-05 13:14:58 -0800974 if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) {
Tejun Heo75eb6c32011-10-19 14:31:22 +0200975 rw_flags |= REQ_ELVPRIV;
Tejun Heo8a5ecdd2012-06-04 20:40:58 -0700976 q->nr_rqs_elvpriv++;
Tejun Heof1f8cc92011-12-14 00:33:42 +0100977 if (et->icq_cache && ioc)
978 icq = ioc_lookup_icq(ioc, q);
Mike Snitzer9d5a4e92011-02-11 11:05:46 +0100979 }
Tejun Heocb98fc82005-10-28 08:29:39 +0200980
Jens Axboef253b862010-10-24 22:06:02 +0200981 if (blk_queue_io_stat(q))
982 rw_flags |= REQ_IO_STAT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983 spin_unlock_irq(q->queue_lock);
984
Tejun Heo29e2b092012-04-19 16:29:21 -0700985 /* allocate and init request */
Tejun Heo5b788ce2012-06-04 20:40:59 -0700986 rq = mempool_alloc(rl->rq_pool, gfp_mask);
Tejun Heo29e2b092012-04-19 16:29:21 -0700987 if (!rq)
Tejun Heob6792812012-03-05 13:15:23 -0800988 goto fail_alloc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700989
Tejun Heo29e2b092012-04-19 16:29:21 -0700990 blk_rq_init(q, rq);
Tejun Heoa0516612012-06-26 15:05:44 -0700991 blk_rq_set_rl(rq, rl);
Tejun Heo29e2b092012-04-19 16:29:21 -0700992 rq->cmd_flags = rw_flags | REQ_ALLOCED;
993
Tejun Heoaaf7c682012-04-19 16:29:22 -0700994 /* init elvpriv */
Tejun Heo29e2b092012-04-19 16:29:21 -0700995 if (rw_flags & REQ_ELVPRIV) {
Tejun Heoaaf7c682012-04-19 16:29:22 -0700996 if (unlikely(et->icq_cache && !icq)) {
Tejun Heo7f4b35d2012-06-04 20:40:56 -0700997 if (ioc)
998 icq = ioc_create_icq(ioc, q, gfp_mask);
Tejun Heoaaf7c682012-04-19 16:29:22 -0700999 if (!icq)
1000 goto fail_elvpriv;
Tejun Heo29e2b092012-04-19 16:29:21 -07001001 }
Tejun Heoaaf7c682012-04-19 16:29:22 -07001002
1003 rq->elv.icq = icq;
1004 if (unlikely(elv_set_request(q, rq, bio, gfp_mask)))
1005 goto fail_elvpriv;
1006
1007 /* @rq->elv.icq holds io_context until @rq is freed */
Tejun Heo29e2b092012-04-19 16:29:21 -07001008 if (icq)
1009 get_io_context(icq->ioc);
1010 }
Tejun Heoaaf7c682012-04-19 16:29:22 -07001011out:
Jens Axboe88ee5ef2005-11-12 11:09:12 +01001012 /*
1013 * ioc may be NULL here, and ioc_batching will be false. That's
1014 * OK, if the queue is under the request limit then requests need
1015 * not count toward the nr_batch_requests limit. There will always
1016 * be some limit enforced by BLK_BATCH_TIME.
1017 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018 if (ioc_batching(q, ioc))
1019 ioc->nr_batch_requests--;
Jens Axboe6728cb02008-01-31 13:03:55 +01001020
Jens Axboe1faa16d2009-04-06 14:48:01 +02001021 trace_block_getrq(q, bio, rw_flags & 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022 return rq;
Tejun Heob6792812012-03-05 13:15:23 -08001023
Tejun Heoaaf7c682012-04-19 16:29:22 -07001024fail_elvpriv:
1025 /*
1026 * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed
1027 * and may fail indefinitely under memory pressure and thus
1028 * shouldn't stall IO. Treat this request as !elvpriv. This will
1029 * disturb iosched and blkcg but weird is bettern than dead.
1030 */
1031 printk_ratelimited(KERN_WARNING "%s: request aux data allocation failed, iosched may be disturbed\n",
1032 dev_name(q->backing_dev_info.dev));
1033
1034 rq->cmd_flags &= ~REQ_ELVPRIV;
1035 rq->elv.icq = NULL;
1036
1037 spin_lock_irq(q->queue_lock);
Tejun Heo8a5ecdd2012-06-04 20:40:58 -07001038 q->nr_rqs_elvpriv--;
Tejun Heoaaf7c682012-04-19 16:29:22 -07001039 spin_unlock_irq(q->queue_lock);
1040 goto out;
1041
Tejun Heob6792812012-03-05 13:15:23 -08001042fail_alloc:
1043 /*
1044 * Allocation failed presumably due to memory. Undo anything we
1045 * might have messed up.
1046 *
1047 * Allocating task should really be put onto the front of the wait
1048 * queue, but this is pretty rare.
1049 */
1050 spin_lock_irq(q->queue_lock);
Tejun Heo5b788ce2012-06-04 20:40:59 -07001051 freed_request(rl, rw_flags);
Tejun Heob6792812012-03-05 13:15:23 -08001052
1053 /*
1054 * in the very unlikely event that allocation failed and no
1055 * requests for this direction was pending, mark us starved so that
1056 * freeing of a request in the other direction will notice
1057 * us. another possible fix would be to split the rq mempool into
1058 * READ and WRITE
1059 */
1060rq_starved:
1061 if (unlikely(rl->count[is_sync] == 0))
1062 rl->starved[is_sync] = 1;
1063 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064}
1065
Tejun Heoda8303c2011-10-19 14:33:05 +02001066/**
Tejun Heoa06e05e2012-06-04 20:40:55 -07001067 * get_request - get a free request
Tejun Heoda8303c2011-10-19 14:33:05 +02001068 * @q: request_queue to allocate request from
1069 * @rw_flags: RW and SYNC flags
1070 * @bio: bio to allocate request for (can be %NULL)
Tejun Heoa06e05e2012-06-04 20:40:55 -07001071 * @gfp_mask: allocation mask
Nick Piggind6344532005-06-28 20:45:14 -07001072 *
Tejun Heoa06e05e2012-06-04 20:40:55 -07001073 * Get a free request from @q. If %__GFP_WAIT is set in @gfp_mask, this
1074 * function keeps retrying under memory pressure and fails iff @q is dead.
Tejun Heoda8303c2011-10-19 14:33:05 +02001075 *
1076 * Must be callled with @q->queue_lock held and,
1077 * Returns %NULL on failure, with @q->queue_lock held.
1078 * Returns !%NULL on success, with @q->queue_lock *not held*.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079 */
Tejun Heoa06e05e2012-06-04 20:40:55 -07001080static struct request *get_request(struct request_queue *q, int rw_flags,
1081 struct bio *bio, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001082{
Jens Axboe1faa16d2009-04-06 14:48:01 +02001083 const bool is_sync = rw_is_sync(rw_flags) != 0;
Tejun Heoa06e05e2012-06-04 20:40:55 -07001084 DEFINE_WAIT(wait);
Tejun Heoa0516612012-06-26 15:05:44 -07001085 struct request_list *rl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001086 struct request *rq;
Tejun Heoa0516612012-06-26 15:05:44 -07001087
1088 rl = blk_get_rl(q, bio); /* transferred to @rq on success */
Tejun Heoa06e05e2012-06-04 20:40:55 -07001089retry:
Tejun Heoa0516612012-06-26 15:05:44 -07001090 rq = __get_request(rl, rw_flags, bio, gfp_mask);
Tejun Heoa06e05e2012-06-04 20:40:55 -07001091 if (rq)
1092 return rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001093
Bart Van Assche3f3299d2012-11-28 13:42:38 +01001094 if (!(gfp_mask & __GFP_WAIT) || unlikely(blk_queue_dying(q))) {
Tejun Heoa0516612012-06-26 15:05:44 -07001095 blk_put_rl(rl);
Tejun Heoa06e05e2012-06-04 20:40:55 -07001096 return NULL;
Tejun Heoa0516612012-06-26 15:05:44 -07001097 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001098
Tejun Heoa06e05e2012-06-04 20:40:55 -07001099 /* wait on @rl and retry */
1100 prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
1101 TASK_UNINTERRUPTIBLE);
Tejun Heoda8303c2011-10-19 14:33:05 +02001102
Tejun Heoa06e05e2012-06-04 20:40:55 -07001103 trace_block_sleeprq(q, bio, rw_flags & 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001104
Tejun Heoa06e05e2012-06-04 20:40:55 -07001105 spin_unlock_irq(q->queue_lock);
1106 io_schedule();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001107
Tejun Heoa06e05e2012-06-04 20:40:55 -07001108 /*
1109 * After sleeping, we become a "batching" process and will be able
1110 * to allocate at least one request, and up to a big batch of them
1111 * for a small period time. See ioc_batching, ioc_set_batching
1112 */
Tejun Heoa06e05e2012-06-04 20:40:55 -07001113 ioc_set_batching(q, current->io_context);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114
Tejun Heoa06e05e2012-06-04 20:40:55 -07001115 spin_lock_irq(q->queue_lock);
1116 finish_wait(&rl->wait[is_sync], &wait);
Jens Axboe2056a782006-03-23 20:00:26 +01001117
Tejun Heoa06e05e2012-06-04 20:40:55 -07001118 goto retry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119}
1120
Jens Axboe165125e2007-07-24 09:28:11 +02001121struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122{
1123 struct request *rq;
1124
1125 BUG_ON(rw != READ && rw != WRITE);
1126
Tejun Heo7f4b35d2012-06-04 20:40:56 -07001127 /* create ioc upfront */
1128 create_io_context(gfp_mask, q->node);
1129
Nick Piggind6344532005-06-28 20:45:14 -07001130 spin_lock_irq(q->queue_lock);
Tejun Heoa06e05e2012-06-04 20:40:55 -07001131 rq = get_request(q, rw, NULL, gfp_mask);
Tejun Heoda8303c2011-10-19 14:33:05 +02001132 if (!rq)
1133 spin_unlock_irq(q->queue_lock);
Nick Piggind6344532005-06-28 20:45:14 -07001134 /* q->queue_lock is unlocked at this point */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001135
1136 return rq;
1137}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001138EXPORT_SYMBOL(blk_get_request);
1139
1140/**
Boaz Harrosh79eb63e2009-05-17 18:57:15 +03001141 * blk_make_request - given a bio, allocate a corresponding struct request.
Randy Dunlap8ebf9752009-06-11 20:00:41 -07001142 * @q: target request queue
Boaz Harrosh79eb63e2009-05-17 18:57:15 +03001143 * @bio: The bio describing the memory mappings that will be submitted for IO.
1144 * It may be a chained-bio properly constructed by block/bio layer.
Randy Dunlap8ebf9752009-06-11 20:00:41 -07001145 * @gfp_mask: gfp flags to be used for memory allocation
Jens Axboedc72ef42006-07-20 14:54:05 +02001146 *
Boaz Harrosh79eb63e2009-05-17 18:57:15 +03001147 * blk_make_request is the parallel of generic_make_request for BLOCK_PC
1148 * type commands. Where the struct request needs to be farther initialized by
1149 * the caller. It is passed a &struct bio, which describes the memory info of
1150 * the I/O transfer.
1151 *
1152 * The caller of blk_make_request must make sure that bi_io_vec
1153 * are set to describe the memory buffers. That bio_data_dir() will return
1154 * the needed direction of the request. (And all bio's in the passed bio-chain
1155 * are properly set accordingly)
1156 *
1157 * If called under none-sleepable conditions, mapped bio buffers must not
1158 * need bouncing, by calling the appropriate masked or flagged allocator,
1159 * suitable for the target device. Otherwise the call to blk_queue_bounce will
1160 * BUG.
Jens Axboe53674ac2009-05-19 19:52:35 +02001161 *
1162 * WARNING: When allocating/cloning a bio-chain, careful consideration should be
1163 * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for
1164 * anything but the first bio in the chain. Otherwise you risk waiting for IO
1165 * completion of a bio that hasn't been submitted yet, thus resulting in a
1166 * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead
1167 * of bio_alloc(), as that avoids the mempool deadlock.
1168 * If possible a big IO should be split into smaller parts when allocation
1169 * fails. Partial allocation should not be an error, or you risk a live-lock.
Jens Axboedc72ef42006-07-20 14:54:05 +02001170 */
Boaz Harrosh79eb63e2009-05-17 18:57:15 +03001171struct request *blk_make_request(struct request_queue *q, struct bio *bio,
1172 gfp_t gfp_mask)
Jens Axboedc72ef42006-07-20 14:54:05 +02001173{
Boaz Harrosh79eb63e2009-05-17 18:57:15 +03001174 struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask);
1175
1176 if (unlikely(!rq))
1177 return ERR_PTR(-ENOMEM);
1178
1179 for_each_bio(bio) {
1180 struct bio *bounce_bio = bio;
1181 int ret;
1182
1183 blk_queue_bounce(q, &bounce_bio);
1184 ret = blk_rq_append_bio(q, rq, bounce_bio);
1185 if (unlikely(ret)) {
1186 blk_put_request(rq);
1187 return ERR_PTR(ret);
1188 }
1189 }
1190
1191 return rq;
Jens Axboedc72ef42006-07-20 14:54:05 +02001192}
Boaz Harrosh79eb63e2009-05-17 18:57:15 +03001193EXPORT_SYMBOL(blk_make_request);
Jens Axboedc72ef42006-07-20 14:54:05 +02001194
1195/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001196 * blk_requeue_request - put a request back on queue
1197 * @q: request queue where request should be inserted
1198 * @rq: request to be inserted
1199 *
1200 * Description:
1201 * Drivers often keep queueing requests until the hardware cannot accept
1202 * more, when that condition happens we need to put the request back
1203 * on the queue. Must be called with queue lock held.
1204 */
Jens Axboe165125e2007-07-24 09:28:11 +02001205void blk_requeue_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206{
Jens Axboe242f9dc2008-09-14 05:55:09 -07001207 blk_delete_timer(rq);
1208 blk_clear_rq_complete(rq);
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +01001209 trace_block_rq_requeue(q, rq);
Jens Axboe2056a782006-03-23 20:00:26 +01001210
Linus Torvalds1da177e2005-04-16 15:20:36 -07001211 if (blk_rq_tagged(rq))
1212 blk_queue_end_tag(q, rq);
1213
James Bottomleyba396a62009-05-27 14:17:08 +02001214 BUG_ON(blk_queued_rq(rq));
1215
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216 elv_requeue_request(q, rq);
1217}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218EXPORT_SYMBOL(blk_requeue_request);
1219
Jens Axboe73c10102011-03-08 13:19:51 +01001220static void add_acct_request(struct request_queue *q, struct request *rq,
1221 int where)
1222{
1223 drive_stat_acct(rq, 1);
Jens Axboe7eaceac2011-03-10 08:52:07 +01001224 __elv_add_request(q, rq, where);
Jens Axboe73c10102011-03-08 13:19:51 +01001225}
1226
Tejun Heo074a7ac2008-08-25 19:56:14 +09001227static void part_round_stats_single(int cpu, struct hd_struct *part,
1228 unsigned long now)
1229{
1230 if (now == part->stamp)
1231 return;
1232
Nikanth Karthikesan316d3152009-10-06 20:16:55 +02001233 if (part_in_flight(part)) {
Tejun Heo074a7ac2008-08-25 19:56:14 +09001234 __part_stat_add(cpu, part, time_in_queue,
Nikanth Karthikesan316d3152009-10-06 20:16:55 +02001235 part_in_flight(part) * (now - part->stamp));
Tejun Heo074a7ac2008-08-25 19:56:14 +09001236 __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
1237 }
1238 part->stamp = now;
1239}
1240
1241/**
Randy Dunlap496aa8a2008-10-16 07:46:23 +02001242 * part_round_stats() - Round off the performance stats on a struct disk_stats.
1243 * @cpu: cpu number for stats access
1244 * @part: target partition
Linus Torvalds1da177e2005-04-16 15:20:36 -07001245 *
1246 * The average IO queue length and utilisation statistics are maintained
1247 * by observing the current state of the queue length and the amount of
1248 * time it has been in this state for.
1249 *
1250 * Normally, that accounting is done on IO completion, but that can result
1251 * in more than a second's worth of IO being accounted for within any one
1252 * second, leading to >100% utilisation. To deal with that, we call this
1253 * function to do a round-off before returning the results when reading
1254 * /proc/diskstats. This accounts immediately for all queue usage up to
1255 * the current jiffies and restarts the counters again.
1256 */
Tejun Heoc9959052008-08-25 19:47:21 +09001257void part_round_stats(int cpu, struct hd_struct *part)
Jerome Marchand6f2576a2008-02-08 11:04:35 +01001258{
1259 unsigned long now = jiffies;
1260
Tejun Heo074a7ac2008-08-25 19:56:14 +09001261 if (part->partno)
1262 part_round_stats_single(cpu, &part_to_disk(part)->part0, now);
1263 part_round_stats_single(cpu, part, now);
Jerome Marchand6f2576a2008-02-08 11:04:35 +01001264}
Tejun Heo074a7ac2008-08-25 19:56:14 +09001265EXPORT_SYMBOL_GPL(part_round_stats);
Jerome Marchand6f2576a2008-02-08 11:04:35 +01001266
Linus Torvalds1da177e2005-04-16 15:20:36 -07001267/*
1268 * queue lock must be held
1269 */
Jens Axboe165125e2007-07-24 09:28:11 +02001270void __blk_put_request(struct request_queue *q, struct request *req)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001271{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272 if (unlikely(!q))
1273 return;
1274 if (unlikely(--req->ref_count))
1275 return;
1276
Tejun Heo8922e162005-10-20 16:23:44 +02001277 elv_completed_request(q, req);
1278
Boaz Harrosh1cd96c22009-03-24 12:35:07 +01001279 /* this is a bio leak */
1280 WARN_ON(req->bio != NULL);
1281
Linus Torvalds1da177e2005-04-16 15:20:36 -07001282 /*
1283 * Request may not have originated from ll_rw_blk. if not,
1284 * it didn't come out of our reserved rq pools
1285 */
Jens Axboe49171e52006-08-10 08:59:11 +02001286 if (req->cmd_flags & REQ_ALLOCED) {
Tejun Heo75eb6c32011-10-19 14:31:22 +02001287 unsigned int flags = req->cmd_flags;
Tejun Heoa0516612012-06-26 15:05:44 -07001288 struct request_list *rl = blk_rq_rl(req);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289
Linus Torvalds1da177e2005-04-16 15:20:36 -07001290 BUG_ON(!list_empty(&req->queuelist));
Jens Axboe98170642006-07-28 09:23:08 +02001291 BUG_ON(!hlist_unhashed(&req->hash));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001292
Tejun Heoa0516612012-06-26 15:05:44 -07001293 blk_free_request(rl, req);
1294 freed_request(rl, flags);
1295 blk_put_rl(rl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001296 }
1297}
Mike Christie6e39b692005-11-11 05:30:24 -06001298EXPORT_SYMBOL_GPL(__blk_put_request);
1299
Linus Torvalds1da177e2005-04-16 15:20:36 -07001300void blk_put_request(struct request *req)
1301{
Tejun Heo8922e162005-10-20 16:23:44 +02001302 unsigned long flags;
Jens Axboe165125e2007-07-24 09:28:11 +02001303 struct request_queue *q = req->q;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001304
FUJITA Tomonori52a93ba2008-07-15 21:21:45 +02001305 spin_lock_irqsave(q->queue_lock, flags);
1306 __blk_put_request(q, req);
1307 spin_unlock_irqrestore(q->queue_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001308}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001309EXPORT_SYMBOL(blk_put_request);
1310
Christoph Hellwig66ac0282010-06-18 16:59:42 +02001311/**
1312 * blk_add_request_payload - add a payload to a request
1313 * @rq: request to update
1314 * @page: page backing the payload
1315 * @len: length of the payload.
1316 *
1317 * This allows to later add a payload to an already submitted request by
1318 * a block driver. The driver needs to take care of freeing the payload
1319 * itself.
1320 *
1321 * Note that this is a quite horrible hack and nothing but handling of
1322 * discard requests should ever use it.
1323 */
1324void blk_add_request_payload(struct request *rq, struct page *page,
1325 unsigned int len)
1326{
1327 struct bio *bio = rq->bio;
1328
1329 bio->bi_io_vec->bv_page = page;
1330 bio->bi_io_vec->bv_offset = 0;
1331 bio->bi_io_vec->bv_len = len;
1332
1333 bio->bi_size = len;
1334 bio->bi_vcnt = 1;
1335 bio->bi_phys_segments = 1;
1336
1337 rq->__data_len = rq->resid_len = len;
1338 rq->nr_phys_segments = 1;
1339 rq->buffer = bio_data(bio);
1340}
1341EXPORT_SYMBOL_GPL(blk_add_request_payload);
1342
Jens Axboe73c10102011-03-08 13:19:51 +01001343static bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
1344 struct bio *bio)
1345{
1346 const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
1347
Jens Axboe73c10102011-03-08 13:19:51 +01001348 if (!ll_back_merge_fn(q, req, bio))
1349 return false;
1350
1351 trace_block_bio_backmerge(q, bio);
1352
1353 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1354 blk_rq_set_mixed_merge(req);
1355
1356 req->biotail->bi_next = bio;
1357 req->biotail = bio;
1358 req->__data_len += bio->bi_size;
1359 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1360
1361 drive_stat_acct(req, 0);
1362 return true;
1363}
1364
1365static bool bio_attempt_front_merge(struct request_queue *q,
1366 struct request *req, struct bio *bio)
1367{
1368 const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
Jens Axboe73c10102011-03-08 13:19:51 +01001369
Jens Axboe73c10102011-03-08 13:19:51 +01001370 if (!ll_front_merge_fn(q, req, bio))
1371 return false;
1372
1373 trace_block_bio_frontmerge(q, bio);
1374
1375 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1376 blk_rq_set_mixed_merge(req);
1377
Jens Axboe73c10102011-03-08 13:19:51 +01001378 bio->bi_next = req->bio;
1379 req->bio = bio;
1380
1381 /*
1382 * may not be valid. if the low level driver said
1383 * it didn't need a bounce buffer then it better
1384 * not touch req->buffer either...
1385 */
1386 req->buffer = bio_data(bio);
1387 req->__sector = bio->bi_sector;
1388 req->__data_len += bio->bi_size;
1389 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1390
1391 drive_stat_acct(req, 0);
1392 return true;
1393}
1394
Tejun Heobd87b582011-10-19 14:33:08 +02001395/**
1396 * attempt_plug_merge - try to merge with %current's plugged list
1397 * @q: request_queue new bio is being queued at
1398 * @bio: new bio being queued
1399 * @request_count: out parameter for number of traversed plugged requests
1400 *
1401 * Determine whether @bio being queued on @q can be merged with a request
1402 * on %current's plugged list. Returns %true if merge was successful,
1403 * otherwise %false.
1404 *
Tejun Heo07c2bd32012-02-08 09:19:42 +01001405 * Plugging coalesces IOs from the same issuer for the same purpose without
1406 * going through @q->queue_lock. As such it's more of an issuing mechanism
1407 * than scheduling, and the request, while may have elvpriv data, is not
1408 * added on the elevator at this point. In addition, we don't have
1409 * reliable access to the elevator outside queue lock. Only check basic
1410 * merging parameters without querying the elevator.
Jens Axboe73c10102011-03-08 13:19:51 +01001411 */
Tejun Heobd87b582011-10-19 14:33:08 +02001412static bool attempt_plug_merge(struct request_queue *q, struct bio *bio,
1413 unsigned int *request_count)
Jens Axboe73c10102011-03-08 13:19:51 +01001414{
1415 struct blk_plug *plug;
1416 struct request *rq;
1417 bool ret = false;
1418
Tejun Heobd87b582011-10-19 14:33:08 +02001419 plug = current->plug;
Jens Axboe73c10102011-03-08 13:19:51 +01001420 if (!plug)
1421 goto out;
Shaohua Li56ebdaf2011-08-24 16:04:34 +02001422 *request_count = 0;
Jens Axboe73c10102011-03-08 13:19:51 +01001423
1424 list_for_each_entry_reverse(rq, &plug->list, queuelist) {
1425 int el_ret;
1426
Shaohua Li1b2e19f2012-04-06 11:37:47 -06001427 if (rq->q == q)
1428 (*request_count)++;
Shaohua Li56ebdaf2011-08-24 16:04:34 +02001429
Tejun Heo07c2bd32012-02-08 09:19:42 +01001430 if (rq->q != q || !blk_rq_merge_ok(rq, bio))
Jens Axboe73c10102011-03-08 13:19:51 +01001431 continue;
1432
Tejun Heo050c8ea2012-02-08 09:19:38 +01001433 el_ret = blk_try_merge(rq, bio);
Jens Axboe73c10102011-03-08 13:19:51 +01001434 if (el_ret == ELEVATOR_BACK_MERGE) {
1435 ret = bio_attempt_back_merge(q, rq, bio);
1436 if (ret)
1437 break;
1438 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
1439 ret = bio_attempt_front_merge(q, rq, bio);
1440 if (ret)
1441 break;
1442 }
1443 }
1444out:
1445 return ret;
1446}
1447
Jens Axboe86db1e22008-01-29 14:53:40 +01001448void init_request_from_bio(struct request *req, struct bio *bio)
Tejun Heo52d9e672006-01-06 09:49:58 +01001449{
Jens Axboe4aff5e22006-08-10 08:44:47 +02001450 req->cmd_type = REQ_TYPE_FS;
Tejun Heo52d9e672006-01-06 09:49:58 +01001451
Christoph Hellwig7b6d91d2010-08-07 18:20:39 +02001452 req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK;
1453 if (bio->bi_rw & REQ_RAHEAD)
Tejun Heoa82afdf2009-07-03 17:48:16 +09001454 req->cmd_flags |= REQ_FAILFAST_MASK;
Jens Axboeb31dc662006-06-13 08:26:10 +02001455
Tejun Heo52d9e672006-01-06 09:49:58 +01001456 req->errors = 0;
Tejun Heoa2dec7b2009-05-07 22:24:44 +09001457 req->__sector = bio->bi_sector;
Tejun Heo52d9e672006-01-06 09:49:58 +01001458 req->ioprio = bio_prio(bio);
NeilBrownbc1c56f2007-08-16 13:31:30 +02001459 blk_rq_bio_prep(req->q, req, bio);
Tejun Heo52d9e672006-01-06 09:49:58 +01001460}
1461
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +02001462void blk_queue_bio(struct request_queue *q, struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001463{
Jiri Slaby5e00d1b2010-08-12 14:31:06 +02001464 const bool sync = !!(bio->bi_rw & REQ_SYNC);
Jens Axboe73c10102011-03-08 13:19:51 +01001465 struct blk_plug *plug;
1466 int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT;
1467 struct request *req;
Shaohua Li56ebdaf2011-08-24 16:04:34 +02001468 unsigned int request_count = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001469
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470 /*
1471 * low level driver can indicate that it wants pages above a
1472 * certain limit bounced to low memory (ie for highmem, or even
1473 * ISA dma in theory)
1474 */
1475 blk_queue_bounce(q, &bio);
1476
Tejun Heo4fed9472010-09-03 11:56:17 +02001477 if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
Jens Axboe73c10102011-03-08 13:19:51 +01001478 spin_lock_irq(q->queue_lock);
Tejun Heoae1b1532011-01-25 12:43:54 +01001479 where = ELEVATOR_INSERT_FLUSH;
Tejun Heo28e7d182010-09-03 11:56:16 +02001480 goto get_rq;
1481 }
1482
Jens Axboe73c10102011-03-08 13:19:51 +01001483 /*
1484 * Check if we can merge with the plugged list before grabbing
1485 * any locks.
1486 */
Tejun Heobd87b582011-10-19 14:33:08 +02001487 if (attempt_plug_merge(q, bio, &request_count))
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +02001488 return;
Jens Axboe73c10102011-03-08 13:19:51 +01001489
1490 spin_lock_irq(q->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001491
1492 el_ret = elv_merge(q, &req, bio);
Jens Axboe73c10102011-03-08 13:19:51 +01001493 if (el_ret == ELEVATOR_BACK_MERGE) {
Jens Axboe73c10102011-03-08 13:19:51 +01001494 if (bio_attempt_back_merge(q, req, bio)) {
Tejun Heo07c2bd32012-02-08 09:19:42 +01001495 elv_bio_merged(q, req, bio);
Jens Axboe73c10102011-03-08 13:19:51 +01001496 if (!attempt_back_merge(q, req))
1497 elv_merged_request(q, req, el_ret);
1498 goto out_unlock;
Tejun Heo80a761f2009-07-03 17:48:17 +09001499 }
Jens Axboe73c10102011-03-08 13:19:51 +01001500 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
Jens Axboe73c10102011-03-08 13:19:51 +01001501 if (bio_attempt_front_merge(q, req, bio)) {
Tejun Heo07c2bd32012-02-08 09:19:42 +01001502 elv_bio_merged(q, req, bio);
Jens Axboe73c10102011-03-08 13:19:51 +01001503 if (!attempt_front_merge(q, req))
1504 elv_merged_request(q, req, el_ret);
1505 goto out_unlock;
1506 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001507 }
1508
Linus Torvalds1da177e2005-04-16 15:20:36 -07001509get_rq:
Nick Piggin450991b2005-06-28 20:45:13 -07001510 /*
Jens Axboe7749a8d2006-12-13 13:02:26 +01001511 * This sync check and mask will be re-done in init_request_from_bio(),
1512 * but we need to set it earlier to expose the sync flag to the
1513 * rq allocator and io schedulers.
1514 */
1515 rw_flags = bio_data_dir(bio);
1516 if (sync)
Christoph Hellwig7b6d91d2010-08-07 18:20:39 +02001517 rw_flags |= REQ_SYNC;
Jens Axboe7749a8d2006-12-13 13:02:26 +01001518
1519 /*
Nick Piggin450991b2005-06-28 20:45:13 -07001520 * Grab a free request. This is might sleep but can not fail.
Nick Piggind6344532005-06-28 20:45:14 -07001521 * Returns with the queue unlocked.
Nick Piggin450991b2005-06-28 20:45:13 -07001522 */
Tejun Heoa06e05e2012-06-04 20:40:55 -07001523 req = get_request(q, rw_flags, bio, GFP_NOIO);
Tejun Heoda8303c2011-10-19 14:33:05 +02001524 if (unlikely(!req)) {
1525 bio_endio(bio, -ENODEV); /* @q is dead */
1526 goto out_unlock;
1527 }
Nick Piggind6344532005-06-28 20:45:14 -07001528
Nick Piggin450991b2005-06-28 20:45:13 -07001529 /*
1530 * After dropping the lock and possibly sleeping here, our request
1531 * may now be mergeable after it had proven unmergeable (above).
1532 * We don't worry about that case for efficiency. It won't happen
1533 * often, and the elevators are able to handle it.
1534 */
Tejun Heo52d9e672006-01-06 09:49:58 +01001535 init_request_from_bio(req, bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536
Tao Ma9562ad92011-10-24 16:11:30 +02001537 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags))
Jens Axboe11ccf112011-07-26 15:01:15 +02001538 req->cpu = raw_smp_processor_id();
Tejun Heodd831002010-09-03 11:56:16 +02001539
Jens Axboe73c10102011-03-08 13:19:51 +01001540 plug = current->plug;
Jens Axboe721a9602011-03-09 11:56:30 +01001541 if (plug) {
Jens Axboedc6d36c2011-04-12 10:28:28 +02001542 /*
1543 * If this is the first request added after a plug, fire
1544 * of a plug trace. If others have been added before, check
1545 * if we have multiple devices in this plug. If so, make a
1546 * note to sort the list before dispatch.
1547 */
1548 if (list_empty(&plug->list))
1549 trace_block_plug(q);
Shaohua Li3540d5e2011-11-16 09:21:50 +01001550 else {
1551 if (!plug->should_sort) {
1552 struct request *__rq;
Jens Axboe73c10102011-03-08 13:19:51 +01001553
Shaohua Li3540d5e2011-11-16 09:21:50 +01001554 __rq = list_entry_rq(plug->list.prev);
1555 if (__rq->q != q)
1556 plug->should_sort = 1;
1557 }
Shaohua Li019ceb72011-11-16 09:21:50 +01001558 if (request_count >= BLK_MAX_REQUEST_COUNT) {
Shaohua Li3540d5e2011-11-16 09:21:50 +01001559 blk_flush_plug_list(plug, false);
Shaohua Li019ceb72011-11-16 09:21:50 +01001560 trace_block_plug(q);
1561 }
Jens Axboe73c10102011-03-08 13:19:51 +01001562 }
Shaohua Lia6327162011-08-24 16:04:32 +02001563 list_add_tail(&req->queuelist, &plug->list);
1564 drive_stat_acct(req, 1);
Jens Axboe73c10102011-03-08 13:19:51 +01001565 } else {
1566 spin_lock_irq(q->queue_lock);
1567 add_acct_request(q, req, where);
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +02001568 __blk_run_queue(q);
Jens Axboe73c10102011-03-08 13:19:51 +01001569out_unlock:
1570 spin_unlock_irq(q->queue_lock);
1571 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001572}
Jens Axboec20e8de2011-09-12 12:03:37 +02001573EXPORT_SYMBOL_GPL(blk_queue_bio); /* for device mapper only */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574
1575/*
1576 * If bio->bi_dev is a partition, remap the location
1577 */
1578static inline void blk_partition_remap(struct bio *bio)
1579{
1580 struct block_device *bdev = bio->bi_bdev;
1581
Jens Axboebf2de6f2007-09-27 13:01:25 +02001582 if (bio_sectors(bio) && bdev != bdev->bd_contains) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001583 struct hd_struct *p = bdev->bd_part;
Jens Axboea3623572005-11-01 09:26:16 +01001584
Linus Torvalds1da177e2005-04-16 15:20:36 -07001585 bio->bi_sector += p->start_sect;
1586 bio->bi_bdev = bdev->bd_contains;
Alan D. Brunellec7149d62007-08-07 15:30:23 +02001587
Mike Snitzerd07335e2010-11-16 12:52:38 +01001588 trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), bio,
1589 bdev->bd_dev,
1590 bio->bi_sector - p->start_sect);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001591 }
1592}
1593
Linus Torvalds1da177e2005-04-16 15:20:36 -07001594static void handle_bad_sector(struct bio *bio)
1595{
1596 char b[BDEVNAME_SIZE];
1597
1598 printk(KERN_INFO "attempt to access beyond end of device\n");
1599 printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
1600 bdevname(bio->bi_bdev, b),
1601 bio->bi_rw,
1602 (unsigned long long)bio->bi_sector + bio_sectors(bio),
Mike Snitzer77304d22010-11-08 14:39:12 +01001603 (long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604
1605 set_bit(BIO_EOF, &bio->bi_flags);
1606}
1607
Akinobu Mitac17bb492006-12-08 02:39:46 -08001608#ifdef CONFIG_FAIL_MAKE_REQUEST
1609
1610static DECLARE_FAULT_ATTR(fail_make_request);
1611
1612static int __init setup_fail_make_request(char *str)
1613{
1614 return setup_fault_attr(&fail_make_request, str);
1615}
1616__setup("fail_make_request=", setup_fail_make_request);
1617
Akinobu Mitab2c9cd32011-07-26 16:09:03 -07001618static bool should_fail_request(struct hd_struct *part, unsigned int bytes)
Akinobu Mitac17bb492006-12-08 02:39:46 -08001619{
Akinobu Mitab2c9cd32011-07-26 16:09:03 -07001620 return part->make_it_fail && should_fail(&fail_make_request, bytes);
Akinobu Mitac17bb492006-12-08 02:39:46 -08001621}
1622
1623static int __init fail_make_request_debugfs(void)
1624{
Akinobu Mitadd48c082011-08-03 16:21:01 -07001625 struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
1626 NULL, &fail_make_request);
1627
1628 return IS_ERR(dir) ? PTR_ERR(dir) : 0;
Akinobu Mitac17bb492006-12-08 02:39:46 -08001629}
1630
1631late_initcall(fail_make_request_debugfs);
1632
1633#else /* CONFIG_FAIL_MAKE_REQUEST */
1634
Akinobu Mitab2c9cd32011-07-26 16:09:03 -07001635static inline bool should_fail_request(struct hd_struct *part,
1636 unsigned int bytes)
Akinobu Mitac17bb492006-12-08 02:39:46 -08001637{
Akinobu Mitab2c9cd32011-07-26 16:09:03 -07001638 return false;
Akinobu Mitac17bb492006-12-08 02:39:46 -08001639}
1640
1641#endif /* CONFIG_FAIL_MAKE_REQUEST */
1642
Jens Axboec07e2b42007-07-18 13:27:58 +02001643/*
1644 * Check whether this bio extends beyond the end of the device.
1645 */
1646static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
1647{
1648 sector_t maxsector;
1649
1650 if (!nr_sectors)
1651 return 0;
1652
1653 /* Test device or partition size, when known. */
Mike Snitzer77304d22010-11-08 14:39:12 +01001654 maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9;
Jens Axboec07e2b42007-07-18 13:27:58 +02001655 if (maxsector) {
1656 sector_t sector = bio->bi_sector;
1657
1658 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
1659 /*
1660 * This may well happen - the kernel calls bread()
1661 * without checking the size of the device, e.g., when
1662 * mounting a device.
1663 */
1664 handle_bad_sector(bio);
1665 return 1;
1666 }
1667 }
1668
1669 return 0;
1670}
1671
Christoph Hellwig27a84d52011-09-15 14:01:40 +02001672static noinline_for_stack bool
1673generic_make_request_checks(struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001674{
Jens Axboe165125e2007-07-24 09:28:11 +02001675 struct request_queue *q;
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +02001676 int nr_sectors = bio_sectors(bio);
Jens Axboe51fd77b2007-11-02 08:49:08 +01001677 int err = -EIO;
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +02001678 char b[BDEVNAME_SIZE];
1679 struct hd_struct *part;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680
1681 might_sleep();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001682
Jens Axboec07e2b42007-07-18 13:27:58 +02001683 if (bio_check_eod(bio, nr_sectors))
1684 goto end_io;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001685
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +02001686 q = bdev_get_queue(bio->bi_bdev);
1687 if (unlikely(!q)) {
1688 printk(KERN_ERR
1689 "generic_make_request: Trying to access "
1690 "nonexistent block-device %s (%Lu)\n",
1691 bdevname(bio->bi_bdev, b),
1692 (long long) bio->bi_sector);
1693 goto end_io;
1694 }
1695
Martin K. Petersene2a60da2012-09-18 12:19:25 -04001696 if (likely(bio_is_rw(bio) &&
1697 nr_sectors > queue_max_hw_sectors(q))) {
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +02001698 printk(KERN_ERR "bio too big device %s (%u > %u)\n",
1699 bdevname(bio->bi_bdev, b),
1700 bio_sectors(bio),
1701 queue_max_hw_sectors(q));
1702 goto end_io;
1703 }
1704
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +02001705 part = bio->bi_bdev->bd_part;
1706 if (should_fail_request(part, bio->bi_size) ||
1707 should_fail_request(&part_to_disk(part)->part0,
1708 bio->bi_size))
1709 goto end_io;
1710
Linus Torvalds1da177e2005-04-16 15:20:36 -07001711 /*
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +02001712 * If this device has partitions, remap block n
1713 * of partition p to block n+start(p) of the disk.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001714 */
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +02001715 blk_partition_remap(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +02001717 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio))
1718 goto end_io;
1719
1720 if (bio_check_eod(bio, nr_sectors))
1721 goto end_io;
1722
1723 /*
1724 * Filter flush bio's early so that make_request based
1725 * drivers without flush support don't have to worry
1726 * about them.
1727 */
1728 if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) {
1729 bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA);
1730 if (!nr_sectors) {
1731 err = 0;
Tejun Heoa7384672008-11-28 13:32:03 +09001732 goto end_io;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001733 }
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +02001734 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001735
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +02001736 if ((bio->bi_rw & REQ_DISCARD) &&
1737 (!blk_queue_discard(q) ||
Martin K. Petersene2a60da2012-09-18 12:19:25 -04001738 ((bio->bi_rw & REQ_SECURE) && !blk_queue_secdiscard(q)))) {
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +02001739 err = -EOPNOTSUPP;
1740 goto end_io;
1741 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001742
Martin K. Petersen4363ac72012-09-18 12:19:27 -04001743 if (bio->bi_rw & REQ_WRITE_SAME && !bdev_write_same(bio->bi_bdev)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744 err = -EOPNOTSUPP;
1745 goto end_io;
1746 }
1747
Tejun Heo7f4b35d2012-06-04 20:40:56 -07001748 /*
1749 * Various block parts want %current->io_context and lazy ioc
1750 * allocation ends up trading a lot of pain for a small amount of
1751 * memory. Just allocate it upfront. This may fail and block
1752 * layer knows how to live with it.
1753 */
1754 create_io_context(GFP_ATOMIC, q->node);
1755
Tejun Heobc16a4f2011-10-19 14:33:01 +02001756 if (blk_throtl_bio(q, bio))
1757 return false; /* throttled, will be resubmitted later */
Christoph Hellwig27a84d52011-09-15 14:01:40 +02001758
Christoph Hellwig5a7bbad2011-09-12 12:12:01 +02001759 trace_block_bio_queue(q, bio);
Christoph Hellwig27a84d52011-09-15 14:01:40 +02001760 return true;
Tejun Heoa7384672008-11-28 13:32:03 +09001761
1762end_io:
1763 bio_endio(bio, err);
Christoph Hellwig27a84d52011-09-15 14:01:40 +02001764 return false;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001765}
1766
Christoph Hellwig27a84d52011-09-15 14:01:40 +02001767/**
1768 * generic_make_request - hand a buffer to its device driver for I/O
1769 * @bio: The bio describing the location in memory and on the device.
1770 *
1771 * generic_make_request() is used to make I/O requests of block
1772 * devices. It is passed a &struct bio, which describes the I/O that needs
1773 * to be done.
1774 *
1775 * generic_make_request() does not return any status. The
1776 * success/failure status of the request, along with notification of
1777 * completion, is delivered asynchronously through the bio->bi_end_io
1778 * function described (one day) else where.
1779 *
1780 * The caller of generic_make_request must make sure that bi_io_vec
1781 * are set to describe the memory buffer, and that bi_dev and bi_sector are
1782 * set to describe the device address, and the
1783 * bi_end_io and optionally bi_private are set to describe how
1784 * completion notification should be signaled.
1785 *
1786 * generic_make_request and the drivers it calls may use bi_next if this
1787 * bio happens to be merged with someone else, and may resubmit the bio to
1788 * a lower device by calling into generic_make_request recursively, which
1789 * means the bio should NOT be touched after the call to ->make_request_fn.
Neil Brownd89d8792007-05-01 09:53:42 +02001790 */
1791void generic_make_request(struct bio *bio)
1792{
Akinobu Mitabddd87c2010-02-23 08:55:42 +01001793 struct bio_list bio_list_on_stack;
1794
Christoph Hellwig27a84d52011-09-15 14:01:40 +02001795 if (!generic_make_request_checks(bio))
1796 return;
1797
1798 /*
1799 * We only want one ->make_request_fn to be active at a time, else
1800 * stack usage with stacked devices could be a problem. So use
1801 * current->bio_list to keep a list of requests submited by a
1802 * make_request_fn function. current->bio_list is also used as a
1803 * flag to say if generic_make_request is currently active in this
1804 * task or not. If it is NULL, then no make_request is active. If
1805 * it is non-NULL, then a make_request is active, and new requests
1806 * should be added at the tail
1807 */
Akinobu Mitabddd87c2010-02-23 08:55:42 +01001808 if (current->bio_list) {
Akinobu Mitabddd87c2010-02-23 08:55:42 +01001809 bio_list_add(current->bio_list, bio);
Neil Brownd89d8792007-05-01 09:53:42 +02001810 return;
1811 }
Christoph Hellwig27a84d52011-09-15 14:01:40 +02001812
Neil Brownd89d8792007-05-01 09:53:42 +02001813 /* following loop may be a bit non-obvious, and so deserves some
1814 * explanation.
1815 * Before entering the loop, bio->bi_next is NULL (as all callers
1816 * ensure that) so we have a list with a single bio.
1817 * We pretend that we have just taken it off a longer list, so
Akinobu Mitabddd87c2010-02-23 08:55:42 +01001818 * we assign bio_list to a pointer to the bio_list_on_stack,
1819 * thus initialising the bio_list of new bios to be
Christoph Hellwig27a84d52011-09-15 14:01:40 +02001820 * added. ->make_request() may indeed add some more bios
Neil Brownd89d8792007-05-01 09:53:42 +02001821 * through a recursive call to generic_make_request. If it
1822 * did, we find a non-NULL value in bio_list and re-enter the loop
1823 * from the top. In this case we really did just take the bio
Akinobu Mitabddd87c2010-02-23 08:55:42 +01001824 * of the top of the list (no pretending) and so remove it from
Christoph Hellwig27a84d52011-09-15 14:01:40 +02001825 * bio_list, and call into ->make_request() again.
Neil Brownd89d8792007-05-01 09:53:42 +02001826 */
1827 BUG_ON(bio->bi_next);
Akinobu Mitabddd87c2010-02-23 08:55:42 +01001828 bio_list_init(&bio_list_on_stack);
1829 current->bio_list = &bio_list_on_stack;
Neil Brownd89d8792007-05-01 09:53:42 +02001830 do {
Christoph Hellwig27a84d52011-09-15 14:01:40 +02001831 struct request_queue *q = bdev_get_queue(bio->bi_bdev);
1832
1833 q->make_request_fn(q, bio);
1834
Akinobu Mitabddd87c2010-02-23 08:55:42 +01001835 bio = bio_list_pop(current->bio_list);
Neil Brownd89d8792007-05-01 09:53:42 +02001836 } while (bio);
Akinobu Mitabddd87c2010-02-23 08:55:42 +01001837 current->bio_list = NULL; /* deactivate */
Neil Brownd89d8792007-05-01 09:53:42 +02001838}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001839EXPORT_SYMBOL(generic_make_request);
1840
1841/**
Randy Dunlap710027a2008-08-19 20:13:11 +02001842 * submit_bio - submit a bio to the block device layer for I/O
Linus Torvalds1da177e2005-04-16 15:20:36 -07001843 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
1844 * @bio: The &struct bio which describes the I/O
1845 *
1846 * submit_bio() is very similar in purpose to generic_make_request(), and
1847 * uses that function to do most of the work. Both are fairly rough
Randy Dunlap710027a2008-08-19 20:13:11 +02001848 * interfaces; @bio must be presetup and ready for I/O.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001849 *
1850 */
1851void submit_bio(int rw, struct bio *bio)
1852{
Jens Axboe22e2c502005-06-27 10:55:12 +02001853 bio->bi_rw |= rw;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001854
Jens Axboebf2de6f2007-09-27 13:01:25 +02001855 /*
1856 * If it's a regular read/write or a barrier with data attached,
1857 * go through the normal accounting stuff before submission.
1858 */
Martin K. Petersene2a60da2012-09-18 12:19:25 -04001859 if (bio_has_data(bio)) {
Martin K. Petersen4363ac72012-09-18 12:19:27 -04001860 unsigned int count;
1861
1862 if (unlikely(rw & REQ_WRITE_SAME))
1863 count = bdev_logical_block_size(bio->bi_bdev) >> 9;
1864 else
1865 count = bio_sectors(bio);
1866
Jens Axboebf2de6f2007-09-27 13:01:25 +02001867 if (rw & WRITE) {
1868 count_vm_events(PGPGOUT, count);
1869 } else {
1870 task_io_account_read(bio->bi_size);
1871 count_vm_events(PGPGIN, count);
1872 }
1873
1874 if (unlikely(block_dump)) {
1875 char b[BDEVNAME_SIZE];
San Mehat8dcbdc72010-09-14 08:48:01 +02001876 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n",
Pavel Emelyanovba25f9d2007-10-18 23:40:40 -07001877 current->comm, task_pid_nr(current),
Jens Axboebf2de6f2007-09-27 13:01:25 +02001878 (rw & WRITE) ? "WRITE" : "READ",
1879 (unsigned long long)bio->bi_sector,
San Mehat8dcbdc72010-09-14 08:48:01 +02001880 bdevname(bio->bi_bdev, b),
1881 count);
Jens Axboebf2de6f2007-09-27 13:01:25 +02001882 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001883 }
1884
1885 generic_make_request(bio);
1886}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001887EXPORT_SYMBOL(submit_bio);
1888
Kiyoshi Ueda3bcddea2007-12-11 17:52:28 -05001889/**
Kiyoshi Ueda82124d62008-09-18 10:45:38 -04001890 * blk_rq_check_limits - Helper function to check a request for the queue limit
1891 * @q: the queue
1892 * @rq: the request being checked
1893 *
1894 * Description:
1895 * @rq may have been made based on weaker limitations of upper-level queues
1896 * in request stacking drivers, and it may violate the limitation of @q.
1897 * Since the block layer and the underlying device driver trust @rq
1898 * after it is inserted to @q, it should be checked against @q before
1899 * the insertion using this generic function.
1900 *
1901 * This function should also be useful for request stacking drivers
Stefan Weileef35c22010-08-06 21:11:15 +02001902 * in some cases below, so export this function.
Kiyoshi Ueda82124d62008-09-18 10:45:38 -04001903 * Request stacking drivers like request-based dm may change the queue
1904 * limits while requests are in the queue (e.g. dm's table swapping).
1905 * Such request stacking drivers should check those requests agaist
1906 * the new queue limits again when they dispatch those requests,
1907 * although such checkings are also done against the old queue limits
1908 * when submitting requests.
1909 */
1910int blk_rq_check_limits(struct request_queue *q, struct request *rq)
1911{
Martin K. Petersene2a60da2012-09-18 12:19:25 -04001912 if (!rq_mergeable(rq))
ike Snitzer33839772010-08-08 12:11:33 -04001913 return 0;
1914
Martin K. Petersenf31dc1c2012-09-18 12:19:26 -04001915 if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, rq->cmd_flags)) {
Kiyoshi Ueda82124d62008-09-18 10:45:38 -04001916 printk(KERN_ERR "%s: over max size limit.\n", __func__);
1917 return -EIO;
1918 }
1919
1920 /*
1921 * queue's settings related to segment counting like q->bounce_pfn
1922 * may differ from that of other stacking queues.
1923 * Recalculate it to check the request correctly on this queue's
1924 * limitation.
1925 */
1926 blk_recalc_rq_segments(rq);
Martin K. Petersen8a783622010-02-26 00:20:39 -05001927 if (rq->nr_phys_segments > queue_max_segments(q)) {
Kiyoshi Ueda82124d62008-09-18 10:45:38 -04001928 printk(KERN_ERR "%s: over max segments limit.\n", __func__);
1929 return -EIO;
1930 }
1931
1932 return 0;
1933}
1934EXPORT_SYMBOL_GPL(blk_rq_check_limits);
1935
1936/**
1937 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
1938 * @q: the queue to submit the request
1939 * @rq: the request being queued
1940 */
1941int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
1942{
1943 unsigned long flags;
Jeff Moyer4853aba2011-08-15 21:37:25 +02001944 int where = ELEVATOR_INSERT_BACK;
Kiyoshi Ueda82124d62008-09-18 10:45:38 -04001945
1946 if (blk_rq_check_limits(q, rq))
1947 return -EIO;
1948
Akinobu Mitab2c9cd32011-07-26 16:09:03 -07001949 if (rq->rq_disk &&
1950 should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
Kiyoshi Ueda82124d62008-09-18 10:45:38 -04001951 return -EIO;
Kiyoshi Ueda82124d62008-09-18 10:45:38 -04001952
1953 spin_lock_irqsave(q->queue_lock, flags);
Bart Van Assche3f3299d2012-11-28 13:42:38 +01001954 if (unlikely(blk_queue_dying(q))) {
Tejun Heo8ba61432011-12-14 00:33:37 +01001955 spin_unlock_irqrestore(q->queue_lock, flags);
1956 return -ENODEV;
1957 }
Kiyoshi Ueda82124d62008-09-18 10:45:38 -04001958
1959 /*
1960 * Submitting request must be dequeued before calling this function
1961 * because it will be linked to another request_queue
1962 */
1963 BUG_ON(blk_queued_rq(rq));
1964
Jeff Moyer4853aba2011-08-15 21:37:25 +02001965 if (rq->cmd_flags & (REQ_FLUSH|REQ_FUA))
1966 where = ELEVATOR_INSERT_FLUSH;
1967
1968 add_acct_request(q, rq, where);
Jeff Moyere67b77c2011-10-17 12:57:23 +02001969 if (where == ELEVATOR_INSERT_FLUSH)
1970 __blk_run_queue(q);
Kiyoshi Ueda82124d62008-09-18 10:45:38 -04001971 spin_unlock_irqrestore(q->queue_lock, flags);
1972
1973 return 0;
1974}
1975EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
1976
Tejun Heo80a761f2009-07-03 17:48:17 +09001977/**
1978 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
1979 * @rq: request to examine
1980 *
1981 * Description:
1982 * A request could be merge of IOs which require different failure
1983 * handling. This function determines the number of bytes which
1984 * can be failed from the beginning of the request without
1985 * crossing into area which need to be retried further.
1986 *
1987 * Return:
1988 * The number of bytes to fail.
1989 *
1990 * Context:
1991 * queue_lock must be held.
1992 */
1993unsigned int blk_rq_err_bytes(const struct request *rq)
1994{
1995 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
1996 unsigned int bytes = 0;
1997 struct bio *bio;
1998
1999 if (!(rq->cmd_flags & REQ_MIXED_MERGE))
2000 return blk_rq_bytes(rq);
2001
2002 /*
2003 * Currently the only 'mixing' which can happen is between
2004 * different fastfail types. We can safely fail portions
2005 * which have all the failfast bits that the first one has -
2006 * the ones which are at least as eager to fail as the first
2007 * one.
2008 */
2009 for (bio = rq->bio; bio; bio = bio->bi_next) {
2010 if ((bio->bi_rw & ff) != ff)
2011 break;
2012 bytes += bio->bi_size;
2013 }
2014
2015 /* this could lead to infinite loop */
2016 BUG_ON(blk_rq_bytes(rq) && !bytes);
2017 return bytes;
2018}
2019EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
2020
Jens Axboebc58ba92009-01-23 10:54:44 +01002021static void blk_account_io_completion(struct request *req, unsigned int bytes)
2022{
Jens Axboec2553b52009-04-24 08:10:11 +02002023 if (blk_do_io_stat(req)) {
Jens Axboebc58ba92009-01-23 10:54:44 +01002024 const int rw = rq_data_dir(req);
2025 struct hd_struct *part;
2026 int cpu;
2027
2028 cpu = part_stat_lock();
Jerome Marchand09e099d2011-01-05 16:57:38 +01002029 part = req->part;
Jens Axboebc58ba92009-01-23 10:54:44 +01002030 part_stat_add(cpu, part, sectors[rw], bytes >> 9);
2031 part_stat_unlock();
2032 }
2033}
2034
2035static void blk_account_io_done(struct request *req)
2036{
Jens Axboebc58ba92009-01-23 10:54:44 +01002037 /*
Tejun Heodd4c1332010-09-03 11:56:16 +02002038 * Account IO completion. flush_rq isn't accounted as a
2039 * normal IO on queueing nor completion. Accounting the
2040 * containing request is enough.
Jens Axboebc58ba92009-01-23 10:54:44 +01002041 */
Tejun Heo414b4ff2011-01-25 12:43:49 +01002042 if (blk_do_io_stat(req) && !(req->cmd_flags & REQ_FLUSH_SEQ)) {
Jens Axboebc58ba92009-01-23 10:54:44 +01002043 unsigned long duration = jiffies - req->start_time;
2044 const int rw = rq_data_dir(req);
2045 struct hd_struct *part;
2046 int cpu;
2047
2048 cpu = part_stat_lock();
Jerome Marchand09e099d2011-01-05 16:57:38 +01002049 part = req->part;
Jens Axboebc58ba92009-01-23 10:54:44 +01002050
2051 part_stat_inc(cpu, part, ios[rw]);
2052 part_stat_add(cpu, part, ticks[rw], duration);
2053 part_round_stats(cpu, part);
Nikanth Karthikesan316d3152009-10-06 20:16:55 +02002054 part_dec_in_flight(part, rw);
Jens Axboebc58ba92009-01-23 10:54:44 +01002055
Jens Axboe6c23a962011-01-07 08:43:37 +01002056 hd_struct_put(part);
Jens Axboebc58ba92009-01-23 10:54:44 +01002057 part_stat_unlock();
2058 }
2059}
2060
Tejun Heo53a08802008-12-03 12:41:26 +01002061/**
Tejun Heo9934c8c2009-05-08 11:54:16 +09002062 * blk_peek_request - peek at the top of a request queue
2063 * @q: request queue to peek at
Kiyoshi Ueda3bcddea2007-12-11 17:52:28 -05002064 *
2065 * Description:
Tejun Heo9934c8c2009-05-08 11:54:16 +09002066 * Return the request at the top of @q. The returned request
2067 * should be started using blk_start_request() before LLD starts
2068 * processing it.
Kiyoshi Ueda3bcddea2007-12-11 17:52:28 -05002069 *
2070 * Return:
Tejun Heo9934c8c2009-05-08 11:54:16 +09002071 * Pointer to the request at the top of @q if available. Null
2072 * otherwise.
2073 *
2074 * Context:
2075 * queue_lock must be held.
2076 */
2077struct request *blk_peek_request(struct request_queue *q)
Tejun Heo158dbda2009-04-23 11:05:18 +09002078{
2079 struct request *rq;
2080 int ret;
2081
2082 while ((rq = __elv_next_request(q)) != NULL) {
2083 if (!(rq->cmd_flags & REQ_STARTED)) {
2084 /*
2085 * This is the first time the device driver
2086 * sees this request (possibly after
2087 * requeueing). Notify IO scheduler.
2088 */
Christoph Hellwig33659eb2010-08-07 18:17:56 +02002089 if (rq->cmd_flags & REQ_SORTED)
Tejun Heo158dbda2009-04-23 11:05:18 +09002090 elv_activate_rq(q, rq);
2091
2092 /*
2093 * just mark as started even if we don't start
2094 * it, a request that has been delayed should
2095 * not be passed by new incoming requests
2096 */
2097 rq->cmd_flags |= REQ_STARTED;
2098 trace_block_rq_issue(q, rq);
2099 }
2100
2101 if (!q->boundary_rq || q->boundary_rq == rq) {
2102 q->end_sector = rq_end_sector(rq);
2103 q->boundary_rq = NULL;
2104 }
2105
2106 if (rq->cmd_flags & REQ_DONTPREP)
2107 break;
2108
Tejun Heo2e46e8b2009-05-07 22:24:41 +09002109 if (q->dma_drain_size && blk_rq_bytes(rq)) {
Tejun Heo158dbda2009-04-23 11:05:18 +09002110 /*
2111 * make sure space for the drain appears we
2112 * know we can do this because max_hw_segments
2113 * has been adjusted to be one fewer than the
2114 * device can handle
2115 */
2116 rq->nr_phys_segments++;
2117 }
2118
2119 if (!q->prep_rq_fn)
2120 break;
2121
2122 ret = q->prep_rq_fn(q, rq);
2123 if (ret == BLKPREP_OK) {
2124 break;
2125 } else if (ret == BLKPREP_DEFER) {
2126 /*
2127 * the request may have been (partially) prepped.
2128 * we need to keep this request in the front to
2129 * avoid resource deadlock. REQ_STARTED will
2130 * prevent other fs requests from passing this one.
2131 */
Tejun Heo2e46e8b2009-05-07 22:24:41 +09002132 if (q->dma_drain_size && blk_rq_bytes(rq) &&
Tejun Heo158dbda2009-04-23 11:05:18 +09002133 !(rq->cmd_flags & REQ_DONTPREP)) {
2134 /*
2135 * remove the space for the drain we added
2136 * so that we don't add it again
2137 */
2138 --rq->nr_phys_segments;
2139 }
2140
2141 rq = NULL;
2142 break;
2143 } else if (ret == BLKPREP_KILL) {
2144 rq->cmd_flags |= REQ_QUIET;
James Bottomleyc143dc92009-05-30 06:43:49 +02002145 /*
2146 * Mark this request as started so we don't trigger
2147 * any debug logic in the end I/O path.
2148 */
2149 blk_start_request(rq);
Tejun Heo40cbbb72009-04-23 11:05:19 +09002150 __blk_end_request_all(rq, -EIO);
Tejun Heo158dbda2009-04-23 11:05:18 +09002151 } else {
2152 printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
2153 break;
2154 }
2155 }
2156
2157 return rq;
2158}
Tejun Heo9934c8c2009-05-08 11:54:16 +09002159EXPORT_SYMBOL(blk_peek_request);
Tejun Heo158dbda2009-04-23 11:05:18 +09002160
Tejun Heo9934c8c2009-05-08 11:54:16 +09002161void blk_dequeue_request(struct request *rq)
Tejun Heo158dbda2009-04-23 11:05:18 +09002162{
Tejun Heo9934c8c2009-05-08 11:54:16 +09002163 struct request_queue *q = rq->q;
2164
Tejun Heo158dbda2009-04-23 11:05:18 +09002165 BUG_ON(list_empty(&rq->queuelist));
2166 BUG_ON(ELV_ON_HASH(rq));
2167
2168 list_del_init(&rq->queuelist);
2169
2170 /*
2171 * the time frame between a request being removed from the lists
2172 * and to it is freed is accounted as io that is in progress at
2173 * the driver side.
2174 */
Divyesh Shah91952912010-04-01 15:01:41 -07002175 if (blk_account_rq(rq)) {
Jens Axboe0a7ae2f2009-05-20 08:54:31 +02002176 q->in_flight[rq_is_sync(rq)]++;
Divyesh Shah91952912010-04-01 15:01:41 -07002177 set_io_start_time_ns(rq);
2178 }
Tejun Heo158dbda2009-04-23 11:05:18 +09002179}
2180
Tejun Heo5efccd12009-04-23 11:05:18 +09002181/**
Tejun Heo9934c8c2009-05-08 11:54:16 +09002182 * blk_start_request - start request processing on the driver
2183 * @req: request to dequeue
2184 *
2185 * Description:
2186 * Dequeue @req and start timeout timer on it. This hands off the
2187 * request to the driver.
2188 *
2189 * Block internal functions which don't want to start timer should
2190 * call blk_dequeue_request().
2191 *
2192 * Context:
2193 * queue_lock must be held.
2194 */
2195void blk_start_request(struct request *req)
2196{
2197 blk_dequeue_request(req);
2198
2199 /*
Tejun Heo5f49f632009-05-19 18:33:05 +09002200 * We are now handing the request to the hardware, initialize
2201 * resid_len to full count and add the timeout handler.
Tejun Heo9934c8c2009-05-08 11:54:16 +09002202 */
Tejun Heo5f49f632009-05-19 18:33:05 +09002203 req->resid_len = blk_rq_bytes(req);
FUJITA Tomonoridbb66c42009-06-09 05:47:10 +02002204 if (unlikely(blk_bidi_rq(req)))
2205 req->next_rq->resid_len = blk_rq_bytes(req->next_rq);
2206
Tejun Heo9934c8c2009-05-08 11:54:16 +09002207 blk_add_timer(req);
2208}
2209EXPORT_SYMBOL(blk_start_request);
2210
2211/**
2212 * blk_fetch_request - fetch a request from a request queue
2213 * @q: request queue to fetch a request from
2214 *
2215 * Description:
2216 * Return the request at the top of @q. The request is started on
2217 * return and LLD can start processing it immediately.
2218 *
2219 * Return:
2220 * Pointer to the request at the top of @q if available. Null
2221 * otherwise.
2222 *
2223 * Context:
2224 * queue_lock must be held.
2225 */
2226struct request *blk_fetch_request(struct request_queue *q)
2227{
2228 struct request *rq;
2229
2230 rq = blk_peek_request(q);
2231 if (rq)
2232 blk_start_request(rq);
2233 return rq;
2234}
2235EXPORT_SYMBOL(blk_fetch_request);
2236
2237/**
Tejun Heo2e60e022009-04-23 11:05:18 +09002238 * blk_update_request - Special helper function for request stacking drivers
Randy Dunlap8ebf9752009-06-11 20:00:41 -07002239 * @req: the request being processed
Kiyoshi Ueda3bcddea2007-12-11 17:52:28 -05002240 * @error: %0 for success, < %0 for error
Randy Dunlap8ebf9752009-06-11 20:00:41 -07002241 * @nr_bytes: number of bytes to complete @req
Kiyoshi Ueda3bcddea2007-12-11 17:52:28 -05002242 *
2243 * Description:
Randy Dunlap8ebf9752009-06-11 20:00:41 -07002244 * Ends I/O on a number of bytes attached to @req, but doesn't complete
2245 * the request structure even if @req doesn't have leftover.
2246 * If @req has leftover, sets it up for the next range of segments.
Tejun Heo2e60e022009-04-23 11:05:18 +09002247 *
2248 * This special helper function is only for request stacking drivers
2249 * (e.g. request-based dm) so that they can handle partial completion.
2250 * Actual device drivers should use blk_end_request instead.
2251 *
2252 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
2253 * %false return from this function.
Kiyoshi Ueda3bcddea2007-12-11 17:52:28 -05002254 *
2255 * Return:
Tejun Heo2e60e022009-04-23 11:05:18 +09002256 * %false - this request doesn't have any more data
2257 * %true - this request has more data
Kiyoshi Ueda3bcddea2007-12-11 17:52:28 -05002258 **/
Tejun Heo2e60e022009-04-23 11:05:18 +09002259bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002260{
Kiyoshi Ueda5450d3e2007-12-11 17:53:03 -05002261 int total_bytes, bio_nbytes, next_idx = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002262 struct bio *bio;
2263
Tejun Heo2e60e022009-04-23 11:05:18 +09002264 if (!req->bio)
2265 return false;
2266
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +01002267 trace_block_rq_complete(req->q, req);
Jens Axboe2056a782006-03-23 20:00:26 +01002268
Linus Torvalds1da177e2005-04-16 15:20:36 -07002269 /*
Tejun Heo6f414692009-04-19 07:00:41 +09002270 * For fs requests, rq is just carrier of independent bio's
2271 * and each partial completion should be handled separately.
2272 * Reset per-request error on each partial completion.
2273 *
2274 * TODO: tj: This is too subtle. It would be better to let
2275 * low level drivers do what they see fit.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002276 */
Christoph Hellwig33659eb2010-08-07 18:17:56 +02002277 if (req->cmd_type == REQ_TYPE_FS)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002278 req->errors = 0;
2279
Christoph Hellwig33659eb2010-08-07 18:17:56 +02002280 if (error && req->cmd_type == REQ_TYPE_FS &&
2281 !(req->cmd_flags & REQ_QUIET)) {
Hannes Reinecke79775562011-01-18 10:13:13 +01002282 char *error_type;
2283
2284 switch (error) {
2285 case -ENOLINK:
2286 error_type = "recoverable transport";
2287 break;
2288 case -EREMOTEIO:
2289 error_type = "critical target";
2290 break;
2291 case -EBADE:
2292 error_type = "critical nexus";
2293 break;
2294 case -EIO:
2295 default:
2296 error_type = "I/O";
2297 break;
2298 }
Yi Zou37d7b342012-08-30 16:26:25 -07002299 printk_ratelimited(KERN_ERR "end_request: %s error, dev %s, sector %llu\n",
2300 error_type, req->rq_disk ?
2301 req->rq_disk->disk_name : "?",
2302 (unsigned long long)blk_rq_pos(req));
2303
Linus Torvalds1da177e2005-04-16 15:20:36 -07002304 }
2305
Jens Axboebc58ba92009-01-23 10:54:44 +01002306 blk_account_io_completion(req, nr_bytes);
Jens Axboed72d9042005-11-01 08:35:42 +01002307
Linus Torvalds1da177e2005-04-16 15:20:36 -07002308 total_bytes = bio_nbytes = 0;
2309 while ((bio = req->bio) != NULL) {
2310 int nbytes;
2311
2312 if (nr_bytes >= bio->bi_size) {
2313 req->bio = bio->bi_next;
2314 nbytes = bio->bi_size;
NeilBrown5bb23a62007-09-27 12:46:13 +02002315 req_bio_endio(req, bio, nbytes, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002316 next_idx = 0;
2317 bio_nbytes = 0;
2318 } else {
2319 int idx = bio->bi_idx + next_idx;
2320
Kazuhisa Ichikawaaf498d72009-05-12 13:27:45 +02002321 if (unlikely(idx >= bio->bi_vcnt)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002322 blk_dump_rq_flags(req, "__end_that");
Jens Axboe6728cb02008-01-31 13:03:55 +01002323 printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n",
Kazuhisa Ichikawaaf498d72009-05-12 13:27:45 +02002324 __func__, idx, bio->bi_vcnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002325 break;
2326 }
2327
2328 nbytes = bio_iovec_idx(bio, idx)->bv_len;
2329 BIO_BUG_ON(nbytes > bio->bi_size);
2330
2331 /*
2332 * not a complete bvec done
2333 */
2334 if (unlikely(nbytes > nr_bytes)) {
2335 bio_nbytes += nr_bytes;
2336 total_bytes += nr_bytes;
2337 break;
2338 }
2339
2340 /*
2341 * advance to the next vector
2342 */
2343 next_idx++;
2344 bio_nbytes += nbytes;
2345 }
2346
2347 total_bytes += nbytes;
2348 nr_bytes -= nbytes;
2349
Jens Axboe6728cb02008-01-31 13:03:55 +01002350 bio = req->bio;
2351 if (bio) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002352 /*
2353 * end more in this run, or just return 'not-done'
2354 */
2355 if (unlikely(nr_bytes <= 0))
2356 break;
2357 }
2358 }
2359
2360 /*
2361 * completely done
2362 */
Tejun Heo2e60e022009-04-23 11:05:18 +09002363 if (!req->bio) {
2364 /*
2365 * Reset counters so that the request stacking driver
2366 * can find how many bytes remain in the request
2367 * later.
2368 */
Tejun Heoa2dec7b2009-05-07 22:24:44 +09002369 req->__data_len = 0;
Tejun Heo2e60e022009-04-23 11:05:18 +09002370 return false;
2371 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002372
2373 /*
2374 * if the request wasn't completed, update state
2375 */
2376 if (bio_nbytes) {
NeilBrown5bb23a62007-09-27 12:46:13 +02002377 req_bio_endio(req, bio, bio_nbytes, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002378 bio->bi_idx += next_idx;
2379 bio_iovec(bio)->bv_offset += nr_bytes;
2380 bio_iovec(bio)->bv_len -= nr_bytes;
2381 }
2382
Tejun Heoa2dec7b2009-05-07 22:24:44 +09002383 req->__data_len -= total_bytes;
Tejun Heo2e46e8b2009-05-07 22:24:41 +09002384 req->buffer = bio_data(req->bio);
2385
2386 /* update sector only for requests with clear definition of sector */
Martin K. Petersene2a60da2012-09-18 12:19:25 -04002387 if (req->cmd_type == REQ_TYPE_FS)
Tejun Heoa2dec7b2009-05-07 22:24:44 +09002388 req->__sector += total_bytes >> 9;
Tejun Heo2e46e8b2009-05-07 22:24:41 +09002389
Tejun Heo80a761f2009-07-03 17:48:17 +09002390 /* mixed attributes always follow the first bio */
2391 if (req->cmd_flags & REQ_MIXED_MERGE) {
2392 req->cmd_flags &= ~REQ_FAILFAST_MASK;
2393 req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK;
2394 }
2395
Tejun Heo2e46e8b2009-05-07 22:24:41 +09002396 /*
2397 * If total number of sectors is less than the first segment
2398 * size, something has gone terribly wrong.
2399 */
2400 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
Jens Axboe81829242011-03-30 09:51:33 +02002401 blk_dump_rq_flags(req, "request botched");
Tejun Heoa2dec7b2009-05-07 22:24:44 +09002402 req->__data_len = blk_rq_cur_bytes(req);
Tejun Heo2e46e8b2009-05-07 22:24:41 +09002403 }
2404
2405 /* recalculate the number of segments */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002406 blk_recalc_rq_segments(req);
Tejun Heo2e46e8b2009-05-07 22:24:41 +09002407
Tejun Heo2e60e022009-04-23 11:05:18 +09002408 return true;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002409}
Tejun Heo2e60e022009-04-23 11:05:18 +09002410EXPORT_SYMBOL_GPL(blk_update_request);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002411
Tejun Heo2e60e022009-04-23 11:05:18 +09002412static bool blk_update_bidi_request(struct request *rq, int error,
2413 unsigned int nr_bytes,
2414 unsigned int bidi_bytes)
Tejun Heo5efccd12009-04-23 11:05:18 +09002415{
Tejun Heo2e60e022009-04-23 11:05:18 +09002416 if (blk_update_request(rq, error, nr_bytes))
2417 return true;
Tejun Heo5efccd12009-04-23 11:05:18 +09002418
Tejun Heo2e60e022009-04-23 11:05:18 +09002419 /* Bidi request must be completed as a whole */
2420 if (unlikely(blk_bidi_rq(rq)) &&
2421 blk_update_request(rq->next_rq, error, bidi_bytes))
2422 return true;
Tejun Heo5efccd12009-04-23 11:05:18 +09002423
Jens Axboee2e1a142010-06-09 10:42:09 +02002424 if (blk_queue_add_random(rq->q))
2425 add_disk_randomness(rq->rq_disk);
Tejun Heo2e60e022009-04-23 11:05:18 +09002426
2427 return false;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002428}
2429
James Bottomley28018c22010-07-01 19:49:17 +09002430/**
2431 * blk_unprep_request - unprepare a request
2432 * @req: the request
2433 *
2434 * This function makes a request ready for complete resubmission (or
2435 * completion). It happens only after all error handling is complete,
2436 * so represents the appropriate moment to deallocate any resources
2437 * that were allocated to the request in the prep_rq_fn. The queue
2438 * lock is held when calling this.
2439 */
2440void blk_unprep_request(struct request *req)
2441{
2442 struct request_queue *q = req->q;
2443
2444 req->cmd_flags &= ~REQ_DONTPREP;
2445 if (q->unprep_rq_fn)
2446 q->unprep_rq_fn(q, req);
2447}
2448EXPORT_SYMBOL_GPL(blk_unprep_request);
2449
Linus Torvalds1da177e2005-04-16 15:20:36 -07002450/*
2451 * queue lock must be held
2452 */
Tejun Heo2e60e022009-04-23 11:05:18 +09002453static void blk_finish_request(struct request *req, int error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002454{
Kiyoshi Uedab8286232007-12-11 17:53:24 -05002455 if (blk_rq_tagged(req))
2456 blk_queue_end_tag(req->q, req);
2457
James Bottomleyba396a62009-05-27 14:17:08 +02002458 BUG_ON(blk_queued_rq(req));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002459
Christoph Hellwig33659eb2010-08-07 18:17:56 +02002460 if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS)
Matthew Garrett31373d02010-04-06 14:25:14 +02002461 laptop_io_completion(&req->q->backing_dev_info);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002462
Mike Andersone78042e2008-10-30 02:16:20 -07002463 blk_delete_timer(req);
2464
James Bottomley28018c22010-07-01 19:49:17 +09002465 if (req->cmd_flags & REQ_DONTPREP)
2466 blk_unprep_request(req);
2467
2468
Jens Axboebc58ba92009-01-23 10:54:44 +01002469 blk_account_io_done(req);
Kiyoshi Uedab8286232007-12-11 17:53:24 -05002470
Linus Torvalds1da177e2005-04-16 15:20:36 -07002471 if (req->end_io)
Tejun Heo8ffdc652006-01-06 09:49:03 +01002472 req->end_io(req, error);
Kiyoshi Uedab8286232007-12-11 17:53:24 -05002473 else {
2474 if (blk_bidi_rq(req))
2475 __blk_put_request(req->next_rq->q, req->next_rq);
2476
Linus Torvalds1da177e2005-04-16 15:20:36 -07002477 __blk_put_request(req->q, req);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002478 }
2479}
2480
Kiyoshi Ueda3b113132007-12-11 17:41:17 -05002481/**
Tejun Heo2e60e022009-04-23 11:05:18 +09002482 * blk_end_bidi_request - Complete a bidi request
2483 * @rq: the request to complete
Randy Dunlap710027a2008-08-19 20:13:11 +02002484 * @error: %0 for success, < %0 for error
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05002485 * @nr_bytes: number of bytes to complete @rq
2486 * @bidi_bytes: number of bytes to complete @rq->next_rq
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002487 *
2488 * Description:
2489 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
Tejun Heo2e60e022009-04-23 11:05:18 +09002490 * Drivers that supports bidi can safely call this member for any
2491 * type of request, bidi or uni. In the later case @bidi_bytes is
2492 * just ignored.
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002493 *
2494 * Return:
Tejun Heo2e60e022009-04-23 11:05:18 +09002495 * %false - we are done with this request
2496 * %true - still buffers pending for this request
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002497 **/
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002498static bool blk_end_bidi_request(struct request *rq, int error,
2499 unsigned int nr_bytes, unsigned int bidi_bytes)
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002500{
2501 struct request_queue *q = rq->q;
Tejun Heo2e60e022009-04-23 11:05:18 +09002502 unsigned long flags;
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002503
Tejun Heo2e60e022009-04-23 11:05:18 +09002504 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2505 return true;
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002506
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002507 spin_lock_irqsave(q->queue_lock, flags);
Tejun Heo2e60e022009-04-23 11:05:18 +09002508 blk_finish_request(rq, error);
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002509 spin_unlock_irqrestore(q->queue_lock, flags);
2510
Tejun Heo2e60e022009-04-23 11:05:18 +09002511 return false;
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05002512}
Kiyoshi Uedae3a04fe2007-12-11 17:51:46 -05002513
2514/**
Tejun Heo2e60e022009-04-23 11:05:18 +09002515 * __blk_end_bidi_request - Complete a bidi request with queue lock held
2516 * @rq: the request to complete
2517 * @error: %0 for success, < %0 for error
2518 * @nr_bytes: number of bytes to complete @rq
2519 * @bidi_bytes: number of bytes to complete @rq->next_rq
Tejun Heo5efccd12009-04-23 11:05:18 +09002520 *
2521 * Description:
Tejun Heo2e60e022009-04-23 11:05:18 +09002522 * Identical to blk_end_bidi_request() except that queue lock is
2523 * assumed to be locked on entry and remains so on return.
Tejun Heo5efccd12009-04-23 11:05:18 +09002524 *
Tejun Heo2e60e022009-04-23 11:05:18 +09002525 * Return:
2526 * %false - we are done with this request
2527 * %true - still buffers pending for this request
Tejun Heo5efccd12009-04-23 11:05:18 +09002528 **/
Jeff Moyer4853aba2011-08-15 21:37:25 +02002529bool __blk_end_bidi_request(struct request *rq, int error,
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002530 unsigned int nr_bytes, unsigned int bidi_bytes)
Tejun Heo5efccd12009-04-23 11:05:18 +09002531{
Tejun Heo2e60e022009-04-23 11:05:18 +09002532 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2533 return true;
Tejun Heo5efccd12009-04-23 11:05:18 +09002534
Tejun Heo2e60e022009-04-23 11:05:18 +09002535 blk_finish_request(rq, error);
Tejun Heo5efccd12009-04-23 11:05:18 +09002536
Tejun Heo2e60e022009-04-23 11:05:18 +09002537 return false;
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002538}
2539
2540/**
2541 * blk_end_request - Helper function for drivers to complete the request.
2542 * @rq: the request being processed
2543 * @error: %0 for success, < %0 for error
2544 * @nr_bytes: number of bytes to complete
2545 *
2546 * Description:
2547 * Ends I/O on a number of bytes attached to @rq.
2548 * If @rq has leftover, sets it up for the next range of segments.
2549 *
2550 * Return:
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002551 * %false - we are done with this request
2552 * %true - still buffers pending for this request
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002553 **/
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002554bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002555{
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002556 return blk_end_bidi_request(rq, error, nr_bytes, 0);
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002557}
Jens Axboe56ad1742009-07-28 22:11:24 +02002558EXPORT_SYMBOL(blk_end_request);
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002559
2560/**
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002561 * blk_end_request_all - Helper function for drives to finish the request.
2562 * @rq: the request to finish
Randy Dunlap8ebf9752009-06-11 20:00:41 -07002563 * @error: %0 for success, < %0 for error
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002564 *
2565 * Description:
2566 * Completely finish @rq.
2567 */
2568void blk_end_request_all(struct request *rq, int error)
2569{
2570 bool pending;
2571 unsigned int bidi_bytes = 0;
2572
2573 if (unlikely(blk_bidi_rq(rq)))
2574 bidi_bytes = blk_rq_bytes(rq->next_rq);
2575
2576 pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2577 BUG_ON(pending);
2578}
Jens Axboe56ad1742009-07-28 22:11:24 +02002579EXPORT_SYMBOL(blk_end_request_all);
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002580
2581/**
2582 * blk_end_request_cur - Helper function to finish the current request chunk.
2583 * @rq: the request to finish the current chunk for
Randy Dunlap8ebf9752009-06-11 20:00:41 -07002584 * @error: %0 for success, < %0 for error
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002585 *
2586 * Description:
2587 * Complete the current consecutively mapped chunk from @rq.
2588 *
2589 * Return:
2590 * %false - we are done with this request
2591 * %true - still buffers pending for this request
2592 */
2593bool blk_end_request_cur(struct request *rq, int error)
2594{
2595 return blk_end_request(rq, error, blk_rq_cur_bytes(rq));
2596}
Jens Axboe56ad1742009-07-28 22:11:24 +02002597EXPORT_SYMBOL(blk_end_request_cur);
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002598
2599/**
Tejun Heo80a761f2009-07-03 17:48:17 +09002600 * blk_end_request_err - Finish a request till the next failure boundary.
2601 * @rq: the request to finish till the next failure boundary for
2602 * @error: must be negative errno
2603 *
2604 * Description:
2605 * Complete @rq till the next failure boundary.
2606 *
2607 * Return:
2608 * %false - we are done with this request
2609 * %true - still buffers pending for this request
2610 */
2611bool blk_end_request_err(struct request *rq, int error)
2612{
2613 WARN_ON(error >= 0);
2614 return blk_end_request(rq, error, blk_rq_err_bytes(rq));
2615}
2616EXPORT_SYMBOL_GPL(blk_end_request_err);
2617
2618/**
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002619 * __blk_end_request - Helper function for drivers to complete the request.
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002620 * @rq: the request being processed
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002621 * @error: %0 for success, < %0 for error
2622 * @nr_bytes: number of bytes to complete
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002623 *
2624 * Description:
2625 * Must be called with queue lock held unlike blk_end_request().
2626 *
2627 * Return:
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002628 * %false - we are done with this request
2629 * %true - still buffers pending for this request
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002630 **/
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002631bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002632{
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002633 return __blk_end_bidi_request(rq, error, nr_bytes, 0);
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002634}
Jens Axboe56ad1742009-07-28 22:11:24 +02002635EXPORT_SYMBOL(__blk_end_request);
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002636
2637/**
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002638 * __blk_end_request_all - Helper function for drives to finish the request.
2639 * @rq: the request to finish
Randy Dunlap8ebf9752009-06-11 20:00:41 -07002640 * @error: %0 for success, < %0 for error
Kiyoshi Ueda336cdb42007-12-11 17:40:30 -05002641 *
2642 * Description:
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002643 * Completely finish @rq. Must be called with queue lock held.
Kiyoshi Ueda32fab442008-09-18 10:45:09 -04002644 */
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002645void __blk_end_request_all(struct request *rq, int error)
Kiyoshi Ueda32fab442008-09-18 10:45:09 -04002646{
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002647 bool pending;
2648 unsigned int bidi_bytes = 0;
2649
2650 if (unlikely(blk_bidi_rq(rq)))
2651 bidi_bytes = blk_rq_bytes(rq->next_rq);
2652
2653 pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2654 BUG_ON(pending);
Kiyoshi Ueda32fab442008-09-18 10:45:09 -04002655}
Jens Axboe56ad1742009-07-28 22:11:24 +02002656EXPORT_SYMBOL(__blk_end_request_all);
Kiyoshi Ueda32fab442008-09-18 10:45:09 -04002657
2658/**
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002659 * __blk_end_request_cur - Helper function to finish the current request chunk.
2660 * @rq: the request to finish the current chunk for
Randy Dunlap8ebf9752009-06-11 20:00:41 -07002661 * @error: %0 for success, < %0 for error
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002662 *
2663 * Description:
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002664 * Complete the current consecutively mapped chunk from @rq. Must
2665 * be called with queue lock held.
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002666 *
2667 * Return:
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002668 * %false - we are done with this request
2669 * %true - still buffers pending for this request
2670 */
2671bool __blk_end_request_cur(struct request *rq, int error)
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002672{
FUJITA Tomonorib1f74492009-05-11 17:56:09 +09002673 return __blk_end_request(rq, error, blk_rq_cur_bytes(rq));
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002674}
Jens Axboe56ad1742009-07-28 22:11:24 +02002675EXPORT_SYMBOL(__blk_end_request_cur);
Kiyoshi Uedae19a3ab2007-12-11 17:51:02 -05002676
Tejun Heo80a761f2009-07-03 17:48:17 +09002677/**
2678 * __blk_end_request_err - Finish a request till the next failure boundary.
2679 * @rq: the request to finish till the next failure boundary for
2680 * @error: must be negative errno
2681 *
2682 * Description:
2683 * Complete @rq till the next failure boundary. Must be called
2684 * with queue lock held.
2685 *
2686 * Return:
2687 * %false - we are done with this request
2688 * %true - still buffers pending for this request
2689 */
2690bool __blk_end_request_err(struct request *rq, int error)
2691{
2692 WARN_ON(error >= 0);
2693 return __blk_end_request(rq, error, blk_rq_err_bytes(rq));
2694}
2695EXPORT_SYMBOL_GPL(__blk_end_request_err);
2696
Jens Axboe86db1e22008-01-29 14:53:40 +01002697void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
2698 struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002699{
Tejun Heoa82afdf2009-07-03 17:48:16 +09002700 /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */
Christoph Hellwig7b6d91d2010-08-07 18:20:39 +02002701 rq->cmd_flags |= bio->bi_rw & REQ_WRITE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002702
David Woodhousefb2dce82008-08-05 18:01:53 +01002703 if (bio_has_data(bio)) {
2704 rq->nr_phys_segments = bio_phys_segments(q, bio);
David Woodhousefb2dce82008-08-05 18:01:53 +01002705 rq->buffer = bio_data(bio);
2706 }
Tejun Heoa2dec7b2009-05-07 22:24:44 +09002707 rq->__data_len = bio->bi_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002708 rq->bio = rq->biotail = bio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002709
NeilBrown66846572007-08-16 13:31:28 +02002710 if (bio->bi_bdev)
2711 rq->rq_disk = bio->bi_bdev->bd_disk;
2712}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002713
Ilya Loginov2d4dc892009-11-26 09:16:19 +01002714#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
2715/**
2716 * rq_flush_dcache_pages - Helper function to flush all pages in a request
2717 * @rq: the request to be flushed
2718 *
2719 * Description:
2720 * Flush all pages in @rq.
2721 */
2722void rq_flush_dcache_pages(struct request *rq)
2723{
2724 struct req_iterator iter;
2725 struct bio_vec *bvec;
2726
2727 rq_for_each_segment(bvec, rq, iter)
2728 flush_dcache_page(bvec->bv_page);
2729}
2730EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
2731#endif
2732
Kiyoshi Uedaef9e3fa2008-10-01 16:12:15 +02002733/**
2734 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
2735 * @q : the queue of the device being checked
2736 *
2737 * Description:
2738 * Check if underlying low-level drivers of a device are busy.
2739 * If the drivers want to export their busy state, they must set own
2740 * exporting function using blk_queue_lld_busy() first.
2741 *
2742 * Basically, this function is used only by request stacking drivers
2743 * to stop dispatching requests to underlying devices when underlying
2744 * devices are busy. This behavior helps more I/O merging on the queue
2745 * of the request stacking driver and prevents I/O throughput regression
2746 * on burst I/O load.
2747 *
2748 * Return:
2749 * 0 - Not busy (The request stacking driver should dispatch request)
2750 * 1 - Busy (The request stacking driver should stop dispatching request)
2751 */
2752int blk_lld_busy(struct request_queue *q)
2753{
2754 if (q->lld_busy_fn)
2755 return q->lld_busy_fn(q);
2756
2757 return 0;
2758}
2759EXPORT_SYMBOL_GPL(blk_lld_busy);
2760
Kiyoshi Uedab0fd2712009-06-11 13:10:16 +02002761/**
2762 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
2763 * @rq: the clone request to be cleaned up
2764 *
2765 * Description:
2766 * Free all bios in @rq for a cloned request.
2767 */
2768void blk_rq_unprep_clone(struct request *rq)
2769{
2770 struct bio *bio;
2771
2772 while ((bio = rq->bio) != NULL) {
2773 rq->bio = bio->bi_next;
2774
2775 bio_put(bio);
2776 }
2777}
2778EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
2779
2780/*
2781 * Copy attributes of the original request to the clone request.
2782 * The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not copied.
2783 */
2784static void __blk_rq_prep_clone(struct request *dst, struct request *src)
2785{
2786 dst->cpu = src->cpu;
Tejun Heo3a2edd02010-09-03 11:56:18 +02002787 dst->cmd_flags = (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE;
Kiyoshi Uedab0fd2712009-06-11 13:10:16 +02002788 dst->cmd_type = src->cmd_type;
2789 dst->__sector = blk_rq_pos(src);
2790 dst->__data_len = blk_rq_bytes(src);
2791 dst->nr_phys_segments = src->nr_phys_segments;
2792 dst->ioprio = src->ioprio;
2793 dst->extra_len = src->extra_len;
2794}
2795
2796/**
2797 * blk_rq_prep_clone - Helper function to setup clone request
2798 * @rq: the request to be setup
2799 * @rq_src: original request to be cloned
2800 * @bs: bio_set that bios for clone are allocated from
2801 * @gfp_mask: memory allocation mask for bio
2802 * @bio_ctr: setup function to be called for each clone bio.
2803 * Returns %0 for success, non %0 for failure.
2804 * @data: private data to be passed to @bio_ctr
2805 *
2806 * Description:
2807 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
2808 * The actual data parts of @rq_src (e.g. ->cmd, ->buffer, ->sense)
2809 * are not copied, and copying such parts is the caller's responsibility.
2810 * Also, pages which the original bios are pointing to are not copied
2811 * and the cloned bios just point same pages.
2812 * So cloned bios must be completed before original bios, which means
2813 * the caller must complete @rq before @rq_src.
2814 */
2815int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
2816 struct bio_set *bs, gfp_t gfp_mask,
2817 int (*bio_ctr)(struct bio *, struct bio *, void *),
2818 void *data)
2819{
2820 struct bio *bio, *bio_src;
2821
2822 if (!bs)
2823 bs = fs_bio_set;
2824
2825 blk_rq_init(NULL, rq);
2826
2827 __rq_for_each_bio(bio_src, rq_src) {
Kent Overstreetbf800ef2012-09-06 15:35:02 -07002828 bio = bio_clone_bioset(bio_src, gfp_mask, bs);
Kiyoshi Uedab0fd2712009-06-11 13:10:16 +02002829 if (!bio)
2830 goto free_and_out;
2831
Kiyoshi Uedab0fd2712009-06-11 13:10:16 +02002832 if (bio_ctr && bio_ctr(bio, bio_src, data))
2833 goto free_and_out;
2834
2835 if (rq->bio) {
2836 rq->biotail->bi_next = bio;
2837 rq->biotail = bio;
2838 } else
2839 rq->bio = rq->biotail = bio;
2840 }
2841
2842 __blk_rq_prep_clone(rq, rq_src);
2843
2844 return 0;
2845
2846free_and_out:
2847 if (bio)
Kent Overstreet4254bba2012-09-06 15:35:00 -07002848 bio_put(bio);
Kiyoshi Uedab0fd2712009-06-11 13:10:16 +02002849 blk_rq_unprep_clone(rq);
2850
2851 return -ENOMEM;
2852}
2853EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
2854
Jens Axboe18887ad2008-07-28 13:08:45 +02002855int kblockd_schedule_work(struct request_queue *q, struct work_struct *work)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002856{
2857 return queue_work(kblockd_workqueue, work);
2858}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002859EXPORT_SYMBOL(kblockd_schedule_work);
2860
Vivek Goyale43473b2010-09-15 17:06:35 -04002861int kblockd_schedule_delayed_work(struct request_queue *q,
2862 struct delayed_work *dwork, unsigned long delay)
2863{
2864 return queue_delayed_work(kblockd_workqueue, dwork, delay);
2865}
2866EXPORT_SYMBOL(kblockd_schedule_delayed_work);
2867
Jens Axboe73c10102011-03-08 13:19:51 +01002868#define PLUG_MAGIC 0x91827364
2869
Suresh Jayaraman75df7132011-09-21 10:00:16 +02002870/**
2871 * blk_start_plug - initialize blk_plug and track it inside the task_struct
2872 * @plug: The &struct blk_plug that needs to be initialized
2873 *
2874 * Description:
2875 * Tracking blk_plug inside the task_struct will help with auto-flushing the
2876 * pending I/O should the task end up blocking between blk_start_plug() and
2877 * blk_finish_plug(). This is important from a performance perspective, but
2878 * also ensures that we don't deadlock. For instance, if the task is blocking
2879 * for a memory allocation, memory reclaim could end up wanting to free a
2880 * page belonging to that request that is currently residing in our private
2881 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
2882 * this kind of deadlock.
2883 */
Jens Axboe73c10102011-03-08 13:19:51 +01002884void blk_start_plug(struct blk_plug *plug)
2885{
2886 struct task_struct *tsk = current;
2887
2888 plug->magic = PLUG_MAGIC;
2889 INIT_LIST_HEAD(&plug->list);
NeilBrown048c9372011-04-18 09:52:22 +02002890 INIT_LIST_HEAD(&plug->cb_list);
Jens Axboe73c10102011-03-08 13:19:51 +01002891 plug->should_sort = 0;
2892
2893 /*
2894 * If this is a nested plug, don't actually assign it. It will be
2895 * flushed on its own.
2896 */
2897 if (!tsk->plug) {
2898 /*
2899 * Store ordering should not be needed here, since a potential
2900 * preempt will imply a full memory barrier
2901 */
2902 tsk->plug = plug;
2903 }
2904}
2905EXPORT_SYMBOL(blk_start_plug);
2906
2907static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
2908{
2909 struct request *rqa = container_of(a, struct request, queuelist);
2910 struct request *rqb = container_of(b, struct request, queuelist);
2911
Jianpeng Ma975927b2012-10-25 21:58:17 +02002912 return !(rqa->q < rqb->q ||
2913 (rqa->q == rqb->q && blk_rq_pos(rqa) < blk_rq_pos(rqb)));
Jens Axboe73c10102011-03-08 13:19:51 +01002914}
2915
Jens Axboe49cac012011-04-16 13:51:05 +02002916/*
2917 * If 'from_schedule' is true, then postpone the dispatch of requests
2918 * until a safe kblockd context. We due this to avoid accidental big
2919 * additional stack usage in driver dispatch, in places where the originally
2920 * plugger did not intend it.
2921 */
Jens Axboef6603782011-04-15 15:49:07 +02002922static void queue_unplugged(struct request_queue *q, unsigned int depth,
Jens Axboe49cac012011-04-16 13:51:05 +02002923 bool from_schedule)
Jens Axboe99e22592011-04-18 09:59:55 +02002924 __releases(q->queue_lock)
Jens Axboe94b5eb22011-04-12 10:12:19 +02002925{
Jens Axboe49cac012011-04-16 13:51:05 +02002926 trace_block_unplug(q, depth, !from_schedule);
Jens Axboe99e22592011-04-18 09:59:55 +02002927
Bart Van Assche70460572012-11-28 13:45:56 +01002928 if (from_schedule)
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +02002929 blk_run_queue_async(q);
Bart Van Assche70460572012-11-28 13:45:56 +01002930 else
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +02002931 __blk_run_queue(q);
Bart Van Assche70460572012-11-28 13:45:56 +01002932 spin_unlock(q->queue_lock);
Jens Axboe94b5eb22011-04-12 10:12:19 +02002933}
2934
NeilBrown74018dc2012-07-31 09:08:15 +02002935static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)
NeilBrown048c9372011-04-18 09:52:22 +02002936{
2937 LIST_HEAD(callbacks);
2938
Shaohua Li2a7d5552012-07-31 09:08:15 +02002939 while (!list_empty(&plug->cb_list)) {
2940 list_splice_init(&plug->cb_list, &callbacks);
NeilBrown048c9372011-04-18 09:52:22 +02002941
Shaohua Li2a7d5552012-07-31 09:08:15 +02002942 while (!list_empty(&callbacks)) {
2943 struct blk_plug_cb *cb = list_first_entry(&callbacks,
NeilBrown048c9372011-04-18 09:52:22 +02002944 struct blk_plug_cb,
2945 list);
Shaohua Li2a7d5552012-07-31 09:08:15 +02002946 list_del(&cb->list);
NeilBrown74018dc2012-07-31 09:08:15 +02002947 cb->callback(cb, from_schedule);
Shaohua Li2a7d5552012-07-31 09:08:15 +02002948 }
NeilBrown048c9372011-04-18 09:52:22 +02002949 }
2950}
2951
NeilBrown9cbb1752012-07-31 09:08:14 +02002952struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
2953 int size)
2954{
2955 struct blk_plug *plug = current->plug;
2956 struct blk_plug_cb *cb;
2957
2958 if (!plug)
2959 return NULL;
2960
2961 list_for_each_entry(cb, &plug->cb_list, list)
2962 if (cb->callback == unplug && cb->data == data)
2963 return cb;
2964
2965 /* Not currently on the callback list */
2966 BUG_ON(size < sizeof(*cb));
2967 cb = kzalloc(size, GFP_ATOMIC);
2968 if (cb) {
2969 cb->data = data;
2970 cb->callback = unplug;
2971 list_add(&cb->list, &plug->cb_list);
2972 }
2973 return cb;
2974}
2975EXPORT_SYMBOL(blk_check_plugged);
2976
Jens Axboe49cac012011-04-16 13:51:05 +02002977void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
Jens Axboe73c10102011-03-08 13:19:51 +01002978{
2979 struct request_queue *q;
2980 unsigned long flags;
2981 struct request *rq;
NeilBrown109b8122011-04-11 14:13:10 +02002982 LIST_HEAD(list);
Jens Axboe94b5eb22011-04-12 10:12:19 +02002983 unsigned int depth;
Jens Axboe73c10102011-03-08 13:19:51 +01002984
2985 BUG_ON(plug->magic != PLUG_MAGIC);
2986
NeilBrown74018dc2012-07-31 09:08:15 +02002987 flush_plug_callbacks(plug, from_schedule);
Jens Axboe73c10102011-03-08 13:19:51 +01002988 if (list_empty(&plug->list))
2989 return;
2990
NeilBrown109b8122011-04-11 14:13:10 +02002991 list_splice_init(&plug->list, &list);
2992
2993 if (plug->should_sort) {
2994 list_sort(NULL, &list, plug_rq_cmp);
2995 plug->should_sort = 0;
2996 }
Jens Axboe73c10102011-03-08 13:19:51 +01002997
2998 q = NULL;
Jens Axboe94b5eb22011-04-12 10:12:19 +02002999 depth = 0;
Jens Axboe18811272011-04-12 10:11:24 +02003000
3001 /*
3002 * Save and disable interrupts here, to avoid doing it for every
3003 * queue lock we have to take.
3004 */
Jens Axboe73c10102011-03-08 13:19:51 +01003005 local_irq_save(flags);
NeilBrown109b8122011-04-11 14:13:10 +02003006 while (!list_empty(&list)) {
3007 rq = list_entry_rq(list.next);
Jens Axboe73c10102011-03-08 13:19:51 +01003008 list_del_init(&rq->queuelist);
Jens Axboe73c10102011-03-08 13:19:51 +01003009 BUG_ON(!rq->q);
3010 if (rq->q != q) {
Jens Axboe99e22592011-04-18 09:59:55 +02003011 /*
3012 * This drops the queue lock
3013 */
3014 if (q)
Jens Axboe49cac012011-04-16 13:51:05 +02003015 queue_unplugged(q, depth, from_schedule);
Jens Axboe73c10102011-03-08 13:19:51 +01003016 q = rq->q;
Jens Axboe94b5eb22011-04-12 10:12:19 +02003017 depth = 0;
Jens Axboe73c10102011-03-08 13:19:51 +01003018 spin_lock(q->queue_lock);
3019 }
Tejun Heo8ba61432011-12-14 00:33:37 +01003020
3021 /*
3022 * Short-circuit if @q is dead
3023 */
Bart Van Assche3f3299d2012-11-28 13:42:38 +01003024 if (unlikely(blk_queue_dying(q))) {
Tejun Heo8ba61432011-12-14 00:33:37 +01003025 __blk_end_request_all(rq, -ENODEV);
3026 continue;
3027 }
3028
Jens Axboe73c10102011-03-08 13:19:51 +01003029 /*
3030 * rq is already accounted, so use raw insert
3031 */
Jens Axboe401a18e2011-03-25 16:57:52 +01003032 if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA))
3033 __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH);
3034 else
3035 __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);
Jens Axboe94b5eb22011-04-12 10:12:19 +02003036
3037 depth++;
Jens Axboe73c10102011-03-08 13:19:51 +01003038 }
3039
Jens Axboe99e22592011-04-18 09:59:55 +02003040 /*
3041 * This drops the queue lock
3042 */
3043 if (q)
Jens Axboe49cac012011-04-16 13:51:05 +02003044 queue_unplugged(q, depth, from_schedule);
Jens Axboe73c10102011-03-08 13:19:51 +01003045
Jens Axboe73c10102011-03-08 13:19:51 +01003046 local_irq_restore(flags);
3047}
Jens Axboe73c10102011-03-08 13:19:51 +01003048
3049void blk_finish_plug(struct blk_plug *plug)
3050{
Jens Axboef6603782011-04-15 15:49:07 +02003051 blk_flush_plug_list(plug, false);
Christoph Hellwig88b996c2011-04-15 15:20:10 +02003052
3053 if (plug == current->plug)
3054 current->plug = NULL;
Jens Axboe73c10102011-03-08 13:19:51 +01003055}
3056EXPORT_SYMBOL(blk_finish_plug);
3057
Linus Torvalds1da177e2005-04-16 15:20:36 -07003058int __init blk_dev_init(void)
3059{
Nikanth Karthikesan9eb55b02009-04-27 14:53:54 +02003060 BUILD_BUG_ON(__REQ_NR_BITS > 8 *
3061 sizeof(((struct request *)0)->cmd_flags));
3062
Tejun Heo89b90be2011-01-03 15:01:47 +01003063 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
3064 kblockd_workqueue = alloc_workqueue("kblockd",
3065 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003066 if (!kblockd_workqueue)
3067 panic("Failed to create kblockd\n");
3068
3069 request_cachep = kmem_cache_create("blkdev_requests",
Paul Mundt20c2df82007-07-20 10:11:58 +09003070 sizeof(struct request), 0, SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003071
Jens Axboe8324aa92008-01-29 14:51:59 +01003072 blk_requestq_cachep = kmem_cache_create("blkdev_queue",
Jens Axboe165125e2007-07-24 09:28:11 +02003073 sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003074
Linus Torvalds1da177e2005-04-16 15:20:36 -07003075 return 0;
3076}