blob: 3ea208256e7832d691e7fe5a28e0770131069bfb [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * Block device elevator/IO-scheduler.
3 *
4 * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
5 *
Jens Axboe0fe23472006-09-04 15:41:16 +02006 * 30042000 Jens Axboe <axboe@kernel.dk> :
Linus Torvalds1da177e2005-04-16 15:20:36 -07007 *
8 * Split the elevator a bit so that it is possible to choose a different
9 * one or even write a new "plug in". There are three pieces:
10 * - elevator_fn, inserts a new request in the queue list
11 * - elevator_merge_fn, decides whether a new buffer can be merged with
12 * an existing request
13 * - elevator_dequeue_fn, called when a request is taken off the active list
14 *
15 * 20082000 Dave Jones <davej@suse.de> :
16 * Removed tests for max-bomb-segments, which was breaking elvtune
17 * when run without -bN
18 *
19 * Jens:
20 * - Rework again to work with bio instead of buffer_heads
21 * - loose bi_dev comparisons, partition handling is right now
22 * - completely modularize elevator setup and teardown
23 *
24 */
25#include <linux/kernel.h>
26#include <linux/fs.h>
27#include <linux/blkdev.h>
28#include <linux/elevator.h>
29#include <linux/bio.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030#include <linux/module.h>
31#include <linux/slab.h>
32#include <linux/init.h>
33#include <linux/compiler.h>
Tejun Heocb98fc82005-10-28 08:29:39 +020034#include <linux/delay.h>
Jens Axboe2056a782006-03-23 20:00:26 +010035#include <linux/blktrace_api.h>
Jens Axboe98170642006-07-28 09:23:08 +020036#include <linux/hash.h>
Jens Axboe0835da62008-08-26 09:15:47 +020037#include <linux/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070038
Li Zefan55782132009-06-09 13:43:05 +080039#include <trace/events/block.h>
40
Jens Axboe242f9dc2008-09-14 05:55:09 -070041#include "blk.h"
42
Linus Torvalds1da177e2005-04-16 15:20:36 -070043static DEFINE_SPINLOCK(elv_list_lock);
44static LIST_HEAD(elv_list);
45
46/*
Jens Axboe98170642006-07-28 09:23:08 +020047 * Merge hash stuff.
48 */
49static const int elv_hash_shift = 6;
50#define ELV_HASH_BLOCK(sec) ((sec) >> 3)
Jens Axboe4eb166d2008-02-01 00:37:27 +010051#define ELV_HASH_FN(sec) \
52 (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift))
Jens Axboe98170642006-07-28 09:23:08 +020053#define ELV_HASH_ENTRIES (1 << elv_hash_shift)
Tejun Heo83096eb2009-05-07 22:24:39 +090054#define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
Jens Axboe98170642006-07-28 09:23:08 +020055
56/*
Jens Axboeda775262006-12-20 11:04:12 +010057 * Query io scheduler to see if the current process issuing bio may be
58 * merged with rq.
59 */
60static int elv_iosched_allow_merge(struct request *rq, struct bio *bio)
61{
Jens Axboe165125e2007-07-24 09:28:11 +020062 struct request_queue *q = rq->q;
Jens Axboeb374d182008-10-31 10:05:07 +010063 struct elevator_queue *e = q->elevator;
Jens Axboeda775262006-12-20 11:04:12 +010064
65 if (e->ops->elevator_allow_merge_fn)
66 return e->ops->elevator_allow_merge_fn(q, rq, bio);
67
68 return 1;
69}
70
71/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070072 * can we safely merge with this request?
73 */
Adrian Bunk72ed0bf2008-04-29 09:49:05 +020074int elv_rq_merge_ok(struct request *rq, struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -070075{
76 if (!rq_mergeable(rq))
77 return 0;
78
79 /*
David Woodhousee17fc0a2008-08-09 16:42:20 +010080 * Don't merge file system requests and discard requests
81 */
Christoph Hellwig7b6d91d2010-08-07 18:20:39 +020082 if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD))
David Woodhousee17fc0a2008-08-09 16:42:20 +010083 return 0;
84
85 /*
Adrian Hunter8d57a982010-08-11 14:17:49 -070086 * Don't merge discard requests and secure discard requests
87 */
88 if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE))
89 return 0;
90
91 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 * different data direction or already started, don't merge
93 */
94 if (bio_data_dir(bio) != rq_data_dir(rq))
95 return 0;
96
97 /*
Jens Axboeda775262006-12-20 11:04:12 +010098 * must be same device and not a special request
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 */
Jens Axboebb4067e2006-12-21 21:20:01 +0100100 if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special)
Jens Axboeda775262006-12-20 11:04:12 +0100101 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102
Martin K. Petersen7ba1ba12008-06-30 20:04:41 +0200103 /*
104 * only merge integrity protected bio into ditto rq
105 */
106 if (bio_integrity(bio) != blk_integrity_rq(rq))
107 return 0;
108
Jens Axboeda775262006-12-20 11:04:12 +0100109 if (!elv_iosched_allow_merge(rq, bio))
110 return 0;
111
112 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113}
114EXPORT_SYMBOL(elv_rq_merge_ok);
115
Jens Axboe73c10102011-03-08 13:19:51 +0100116int elv_try_merge(struct request *__rq, struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117{
118 int ret = ELEVATOR_NO_MERGE;
119
120 /*
121 * we can merge and sequence is ok, check if it's possible
122 */
123 if (elv_rq_merge_ok(__rq, bio)) {
Tejun Heo83096eb2009-05-07 22:24:39 +0900124 if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 ret = ELEVATOR_BACK_MERGE;
Tejun Heo83096eb2009-05-07 22:24:39 +0900126 else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 ret = ELEVATOR_FRONT_MERGE;
128 }
129
130 return ret;
131}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133static struct elevator_type *elevator_find(const char *name)
134{
Vasily Tarasova22b1692006-10-11 09:24:27 +0200135 struct elevator_type *e;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136
Matthias Kaehlcke70cee262007-07-10 12:26:24 +0200137 list_for_each_entry(e, &elv_list, list) {
Vasily Tarasova22b1692006-10-11 09:24:27 +0200138 if (!strcmp(e->elevator_name, name))
139 return e;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141
Vasily Tarasova22b1692006-10-11 09:24:27 +0200142 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143}
144
145static void elevator_put(struct elevator_type *e)
146{
147 module_put(e->elevator_owner);
148}
149
150static struct elevator_type *elevator_get(const char *name)
151{
Tejun Heo2824bc932005-10-20 10:56:41 +0200152 struct elevator_type *e;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153
Jens Axboe2a12dcd2007-04-26 14:41:53 +0200154 spin_lock(&elv_list_lock);
Tejun Heo2824bc932005-10-20 10:56:41 +0200155
156 e = elevator_find(name);
Jens Axboee1640942008-02-19 10:20:37 +0100157 if (!e) {
158 char elv[ELV_NAME_MAX + strlen("-iosched")];
159
160 spin_unlock(&elv_list_lock);
161
wzt.wzt@gmail.coma506aed2010-04-02 08:41:14 +0200162 snprintf(elv, sizeof(elv), "%s-iosched", name);
Jens Axboee1640942008-02-19 10:20:37 +0100163
maximilian attemse180f592008-07-01 09:42:47 +0200164 request_module("%s", elv);
Jens Axboee1640942008-02-19 10:20:37 +0100165 spin_lock(&elv_list_lock);
166 e = elevator_find(name);
167 }
168
Tejun Heo2824bc932005-10-20 10:56:41 +0200169 if (e && !try_module_get(e->elevator_owner))
170 e = NULL;
171
Jens Axboe2a12dcd2007-04-26 14:41:53 +0200172 spin_unlock(&elv_list_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173
174 return e;
175}
176
Jens Axboe165125e2007-07-24 09:28:11 +0200177static void *elevator_init_queue(struct request_queue *q,
178 struct elevator_queue *eq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179{
Jens Axboebb37b942006-12-01 10:42:33 +0100180 return eq->ops->elevator_init_fn(q);
Jens Axboebc1c1162006-06-08 08:49:06 +0200181}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182
Jens Axboe165125e2007-07-24 09:28:11 +0200183static void elevator_attach(struct request_queue *q, struct elevator_queue *eq,
Jens Axboebc1c1162006-06-08 08:49:06 +0200184 void *data)
185{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186 q->elevator = eq;
Jens Axboebc1c1162006-06-08 08:49:06 +0200187 eq->elevator_data = data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188}
189
190static char chosen_elevator[16];
191
Nate Diller5f003972006-01-24 10:07:58 +0100192static int __init elevator_setup(char *str)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193{
Chuck Ebbert752a3b72006-01-16 09:47:37 +0100194 /*
195 * Be backwards-compatible with previous kernels, so users
196 * won't get the wrong elevator.
197 */
Jens Axboe492af632009-10-03 09:37:51 +0200198 strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1);
OGAWA Hirofumi9b410462006-03-31 02:30:33 -0800199 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200}
201
202__setup("elevator=", elevator_setup);
203
Al Viro3d1ab402006-03-18 18:35:43 -0500204static struct kobj_type elv_ktype;
205
Jens Axboeb374d182008-10-31 10:05:07 +0100206static struct elevator_queue *elevator_alloc(struct request_queue *q,
Jens Axboe165125e2007-07-24 09:28:11 +0200207 struct elevator_type *e)
Al Viro3d1ab402006-03-18 18:35:43 -0500208{
Jens Axboeb374d182008-10-31 10:05:07 +0100209 struct elevator_queue *eq;
Jens Axboe98170642006-07-28 09:23:08 +0200210 int i;
211
Jens Axboeb374d182008-10-31 10:05:07 +0100212 eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node);
Jens Axboe98170642006-07-28 09:23:08 +0200213 if (unlikely(!eq))
214 goto err;
215
Jens Axboe98170642006-07-28 09:23:08 +0200216 eq->ops = &e->ops;
217 eq->elevator_type = e;
Greg Kroah-Hartmanf9cb0742007-12-17 23:05:35 -0700218 kobject_init(&eq->kobj, &elv_ktype);
Jens Axboe98170642006-07-28 09:23:08 +0200219 mutex_init(&eq->sysfs_lock);
220
Jens Axboeb5deef92006-07-19 23:39:40 +0200221 eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES,
222 GFP_KERNEL, q->node);
Jens Axboe98170642006-07-28 09:23:08 +0200223 if (!eq->hash)
224 goto err;
225
226 for (i = 0; i < ELV_HASH_ENTRIES; i++)
227 INIT_HLIST_HEAD(&eq->hash[i]);
228
Al Viro3d1ab402006-03-18 18:35:43 -0500229 return eq;
Jens Axboe98170642006-07-28 09:23:08 +0200230err:
231 kfree(eq);
232 elevator_put(e);
233 return NULL;
Al Viro3d1ab402006-03-18 18:35:43 -0500234}
235
236static void elevator_release(struct kobject *kobj)
237{
Jens Axboeb374d182008-10-31 10:05:07 +0100238 struct elevator_queue *e;
Jens Axboe98170642006-07-28 09:23:08 +0200239
Jens Axboeb374d182008-10-31 10:05:07 +0100240 e = container_of(kobj, struct elevator_queue, kobj);
Al Viro3d1ab402006-03-18 18:35:43 -0500241 elevator_put(e->elevator_type);
Jens Axboe98170642006-07-28 09:23:08 +0200242 kfree(e->hash);
Al Viro3d1ab402006-03-18 18:35:43 -0500243 kfree(e);
244}
245
Jens Axboe165125e2007-07-24 09:28:11 +0200246int elevator_init(struct request_queue *q, char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247{
248 struct elevator_type *e = NULL;
249 struct elevator_queue *eq;
Jens Axboebc1c1162006-06-08 08:49:06 +0200250 void *data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251
Mike Snitzer1abec4f2010-05-25 13:15:15 -0400252 if (unlikely(q->elevator))
253 return 0;
254
Tejun Heocb98fc82005-10-28 08:29:39 +0200255 INIT_LIST_HEAD(&q->queue_head);
256 q->last_merge = NULL;
257 q->end_sector = 0;
258 q->boundary_rq = NULL;
Tejun Heocb98fc82005-10-28 08:29:39 +0200259
Jens Axboe4eb166d2008-02-01 00:37:27 +0100260 if (name) {
261 e = elevator_get(name);
262 if (!e)
263 return -EINVAL;
264 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265
Jens Axboe4eb166d2008-02-01 00:37:27 +0100266 if (!e && *chosen_elevator) {
267 e = elevator_get(chosen_elevator);
268 if (!e)
269 printk(KERN_ERR "I/O scheduler %s not found\n",
270 chosen_elevator);
271 }
Nate Diller248d5ca2006-01-24 10:09:14 +0100272
Jens Axboe4eb166d2008-02-01 00:37:27 +0100273 if (!e) {
274 e = elevator_get(CONFIG_DEFAULT_IOSCHED);
275 if (!e) {
276 printk(KERN_ERR
277 "Default I/O scheduler not found. " \
278 "Using noop.\n");
279 e = elevator_get("noop");
280 }
Nate Diller5f003972006-01-24 10:07:58 +0100281 }
282
Jens Axboeb5deef92006-07-19 23:39:40 +0200283 eq = elevator_alloc(q, e);
Al Viro3d1ab402006-03-18 18:35:43 -0500284 if (!eq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286
Jens Axboebc1c1162006-06-08 08:49:06 +0200287 data = elevator_init_queue(q, eq);
288 if (!data) {
Al Viro3d1ab402006-03-18 18:35:43 -0500289 kobject_put(&eq->kobj);
Jens Axboebc1c1162006-06-08 08:49:06 +0200290 return -ENOMEM;
291 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292
Jens Axboebc1c1162006-06-08 08:49:06 +0200293 elevator_attach(q, eq, data);
Mike Snitzer1abec4f2010-05-25 13:15:15 -0400294 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295}
Jens Axboe2e662b62006-07-13 11:55:04 +0200296EXPORT_SYMBOL(elevator_init);
297
Jens Axboeb374d182008-10-31 10:05:07 +0100298void elevator_exit(struct elevator_queue *e)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299{
Al Viro3d1ab402006-03-18 18:35:43 -0500300 mutex_lock(&e->sysfs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 if (e->ops->elevator_exit_fn)
302 e->ops->elevator_exit_fn(e);
Al Viro3d1ab402006-03-18 18:35:43 -0500303 e->ops = NULL;
304 mutex_unlock(&e->sysfs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305
Al Viro3d1ab402006-03-18 18:35:43 -0500306 kobject_put(&e->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307}
Jens Axboe2e662b62006-07-13 11:55:04 +0200308EXPORT_SYMBOL(elevator_exit);
309
Jens Axboe98170642006-07-28 09:23:08 +0200310static inline void __elv_rqhash_del(struct request *rq)
311{
312 hlist_del_init(&rq->hash);
313}
314
Jens Axboe165125e2007-07-24 09:28:11 +0200315static void elv_rqhash_del(struct request_queue *q, struct request *rq)
Jens Axboe98170642006-07-28 09:23:08 +0200316{
317 if (ELV_ON_HASH(rq))
318 __elv_rqhash_del(rq);
319}
320
Jens Axboe165125e2007-07-24 09:28:11 +0200321static void elv_rqhash_add(struct request_queue *q, struct request *rq)
Jens Axboe98170642006-07-28 09:23:08 +0200322{
Jens Axboeb374d182008-10-31 10:05:07 +0100323 struct elevator_queue *e = q->elevator;
Jens Axboe98170642006-07-28 09:23:08 +0200324
325 BUG_ON(ELV_ON_HASH(rq));
326 hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]);
327}
328
Jens Axboe165125e2007-07-24 09:28:11 +0200329static void elv_rqhash_reposition(struct request_queue *q, struct request *rq)
Jens Axboe98170642006-07-28 09:23:08 +0200330{
331 __elv_rqhash_del(rq);
332 elv_rqhash_add(q, rq);
333}
334
Jens Axboe165125e2007-07-24 09:28:11 +0200335static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset)
Jens Axboe98170642006-07-28 09:23:08 +0200336{
Jens Axboeb374d182008-10-31 10:05:07 +0100337 struct elevator_queue *e = q->elevator;
Jens Axboe98170642006-07-28 09:23:08 +0200338 struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)];
339 struct hlist_node *entry, *next;
340 struct request *rq;
341
342 hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) {
343 BUG_ON(!ELV_ON_HASH(rq));
344
345 if (unlikely(!rq_mergeable(rq))) {
346 __elv_rqhash_del(rq);
347 continue;
348 }
349
350 if (rq_hash_key(rq) == offset)
351 return rq;
352 }
353
354 return NULL;
355}
356
Tejun Heo8922e162005-10-20 16:23:44 +0200357/*
Jens Axboe2e662b62006-07-13 11:55:04 +0200358 * RB-tree support functions for inserting/lookup/removal of requests
359 * in a sorted RB tree.
360 */
361struct request *elv_rb_add(struct rb_root *root, struct request *rq)
362{
363 struct rb_node **p = &root->rb_node;
364 struct rb_node *parent = NULL;
365 struct request *__rq;
366
367 while (*p) {
368 parent = *p;
369 __rq = rb_entry(parent, struct request, rb_node);
370
Tejun Heo83096eb2009-05-07 22:24:39 +0900371 if (blk_rq_pos(rq) < blk_rq_pos(__rq))
Jens Axboe2e662b62006-07-13 11:55:04 +0200372 p = &(*p)->rb_left;
Tejun Heo83096eb2009-05-07 22:24:39 +0900373 else if (blk_rq_pos(rq) > blk_rq_pos(__rq))
Jens Axboe2e662b62006-07-13 11:55:04 +0200374 p = &(*p)->rb_right;
375 else
376 return __rq;
377 }
378
379 rb_link_node(&rq->rb_node, parent, p);
380 rb_insert_color(&rq->rb_node, root);
381 return NULL;
382}
Jens Axboe2e662b62006-07-13 11:55:04 +0200383EXPORT_SYMBOL(elv_rb_add);
384
385void elv_rb_del(struct rb_root *root, struct request *rq)
386{
387 BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
388 rb_erase(&rq->rb_node, root);
389 RB_CLEAR_NODE(&rq->rb_node);
390}
Jens Axboe2e662b62006-07-13 11:55:04 +0200391EXPORT_SYMBOL(elv_rb_del);
392
393struct request *elv_rb_find(struct rb_root *root, sector_t sector)
394{
395 struct rb_node *n = root->rb_node;
396 struct request *rq;
397
398 while (n) {
399 rq = rb_entry(n, struct request, rb_node);
400
Tejun Heo83096eb2009-05-07 22:24:39 +0900401 if (sector < blk_rq_pos(rq))
Jens Axboe2e662b62006-07-13 11:55:04 +0200402 n = n->rb_left;
Tejun Heo83096eb2009-05-07 22:24:39 +0900403 else if (sector > blk_rq_pos(rq))
Jens Axboe2e662b62006-07-13 11:55:04 +0200404 n = n->rb_right;
405 else
406 return rq;
407 }
408
409 return NULL;
410}
Jens Axboe2e662b62006-07-13 11:55:04 +0200411EXPORT_SYMBOL(elv_rb_find);
412
413/*
Tejun Heo8922e162005-10-20 16:23:44 +0200414 * Insert rq into dispatch queue of q. Queue lock must be held on
Uwe Kleine-Königdbe7f762007-10-20 01:55:04 +0200415 * entry. rq is sort instead into the dispatch queue. To be used by
Jens Axboe2e662b62006-07-13 11:55:04 +0200416 * specific elevators.
Tejun Heo8922e162005-10-20 16:23:44 +0200417 */
Jens Axboe165125e2007-07-24 09:28:11 +0200418void elv_dispatch_sort(struct request_queue *q, struct request *rq)
Tejun Heo8922e162005-10-20 16:23:44 +0200419{
420 sector_t boundary;
Tejun Heo8922e162005-10-20 16:23:44 +0200421 struct list_head *entry;
Jens Axboe4eb166d2008-02-01 00:37:27 +0100422 int stop_flags;
Tejun Heo8922e162005-10-20 16:23:44 +0200423
Jens Axboe73c10102011-03-08 13:19:51 +0100424 BUG_ON(rq->cmd_flags & REQ_ON_PLUG);
425
Tejun Heo06b86242005-10-20 16:46:23 +0200426 if (q->last_merge == rq)
427 q->last_merge = NULL;
Jens Axboe98170642006-07-28 09:23:08 +0200428
429 elv_rqhash_del(q, rq);
430
Tejun Heo15853af2005-11-10 08:52:05 +0100431 q->nr_sorted--;
Tejun Heo06b86242005-10-20 16:46:23 +0200432
Jens Axboe1b47f532005-10-20 16:37:00 +0200433 boundary = q->end_sector;
Christoph Hellwig02e031c2010-11-10 14:54:09 +0100434 stop_flags = REQ_SOFTBARRIER | REQ_STARTED;
Tejun Heo8922e162005-10-20 16:23:44 +0200435 list_for_each_prev(entry, &q->queue_head) {
436 struct request *pos = list_entry_rq(entry);
437
Christoph Hellwig33659eb2010-08-07 18:17:56 +0200438 if ((rq->cmd_flags & REQ_DISCARD) !=
439 (pos->cmd_flags & REQ_DISCARD))
David Woodhousee17fc0a2008-08-09 16:42:20 +0100440 break;
Jens Axboe783660b2007-01-19 11:27:47 +1100441 if (rq_data_dir(rq) != rq_data_dir(pos))
442 break;
Jens Axboe4eb166d2008-02-01 00:37:27 +0100443 if (pos->cmd_flags & stop_flags)
Tejun Heo8922e162005-10-20 16:23:44 +0200444 break;
Tejun Heo83096eb2009-05-07 22:24:39 +0900445 if (blk_rq_pos(rq) >= boundary) {
446 if (blk_rq_pos(pos) < boundary)
Tejun Heo8922e162005-10-20 16:23:44 +0200447 continue;
448 } else {
Tejun Heo83096eb2009-05-07 22:24:39 +0900449 if (blk_rq_pos(pos) >= boundary)
Tejun Heo8922e162005-10-20 16:23:44 +0200450 break;
451 }
Tejun Heo83096eb2009-05-07 22:24:39 +0900452 if (blk_rq_pos(rq) >= blk_rq_pos(pos))
Tejun Heo8922e162005-10-20 16:23:44 +0200453 break;
454 }
455
456 list_add(&rq->queuelist, entry);
457}
Jens Axboe2e662b62006-07-13 11:55:04 +0200458EXPORT_SYMBOL(elv_dispatch_sort);
459
Jens Axboe98170642006-07-28 09:23:08 +0200460/*
Jens Axboe2e662b62006-07-13 11:55:04 +0200461 * Insert rq into dispatch queue of q. Queue lock must be held on
462 * entry. rq is added to the back of the dispatch queue. To be used by
463 * specific elevators.
Jens Axboe98170642006-07-28 09:23:08 +0200464 */
465void elv_dispatch_add_tail(struct request_queue *q, struct request *rq)
466{
467 if (q->last_merge == rq)
468 q->last_merge = NULL;
469
470 elv_rqhash_del(q, rq);
471
472 q->nr_sorted--;
473
474 q->end_sector = rq_end_sector(rq);
475 q->boundary_rq = rq;
476 list_add_tail(&rq->queuelist, &q->queue_head);
477}
Jens Axboe2e662b62006-07-13 11:55:04 +0200478EXPORT_SYMBOL(elv_dispatch_add_tail);
479
Jens Axboe165125e2007-07-24 09:28:11 +0200480int elv_merge(struct request_queue *q, struct request **req, struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481{
Jens Axboeb374d182008-10-31 10:05:07 +0100482 struct elevator_queue *e = q->elevator;
Jens Axboe98170642006-07-28 09:23:08 +0200483 struct request *__rq;
Tejun Heo06b86242005-10-20 16:46:23 +0200484 int ret;
485
Jens Axboe98170642006-07-28 09:23:08 +0200486 /*
Alan D. Brunelle488991e2010-01-29 09:04:08 +0100487 * Levels of merges:
488 * nomerges: No merges at all attempted
489 * noxmerges: Only simple one-hit cache try
490 * merges: All merge tries attempted
491 */
492 if (blk_queue_nomerges(q))
493 return ELEVATOR_NO_MERGE;
494
495 /*
Jens Axboe98170642006-07-28 09:23:08 +0200496 * First try one-hit cache.
497 */
Tejun Heo06b86242005-10-20 16:46:23 +0200498 if (q->last_merge) {
499 ret = elv_try_merge(q->last_merge, bio);
500 if (ret != ELEVATOR_NO_MERGE) {
501 *req = q->last_merge;
502 return ret;
503 }
504 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700505
Alan D. Brunelle488991e2010-01-29 09:04:08 +0100506 if (blk_queue_noxmerges(q))
Alan D. Brunelleac9fafa2008-04-29 14:44:19 +0200507 return ELEVATOR_NO_MERGE;
508
Jens Axboe98170642006-07-28 09:23:08 +0200509 /*
510 * See if our hash lookup can find a potential backmerge.
511 */
512 __rq = elv_rqhash_find(q, bio->bi_sector);
513 if (__rq && elv_rq_merge_ok(__rq, bio)) {
514 *req = __rq;
515 return ELEVATOR_BACK_MERGE;
516 }
517
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518 if (e->ops->elevator_merge_fn)
519 return e->ops->elevator_merge_fn(q, req, bio);
520
521 return ELEVATOR_NO_MERGE;
522}
523
Jens Axboe165125e2007-07-24 09:28:11 +0200524void elv_merged_request(struct request_queue *q, struct request *rq, int type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525{
Jens Axboeb374d182008-10-31 10:05:07 +0100526 struct elevator_queue *e = q->elevator;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527
528 if (e->ops->elevator_merged_fn)
Jens Axboe2e662b62006-07-13 11:55:04 +0200529 e->ops->elevator_merged_fn(q, rq, type);
Tejun Heo06b86242005-10-20 16:46:23 +0200530
Jens Axboe2e662b62006-07-13 11:55:04 +0200531 if (type == ELEVATOR_BACK_MERGE)
532 elv_rqhash_reposition(q, rq);
Jens Axboe98170642006-07-28 09:23:08 +0200533
Tejun Heo06b86242005-10-20 16:46:23 +0200534 q->last_merge = rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535}
536
Jens Axboe165125e2007-07-24 09:28:11 +0200537void elv_merge_requests(struct request_queue *q, struct request *rq,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538 struct request *next)
539{
Jens Axboeb374d182008-10-31 10:05:07 +0100540 struct elevator_queue *e = q->elevator;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542 if (e->ops->elevator_merge_req_fn)
543 e->ops->elevator_merge_req_fn(q, rq, next);
Tejun Heo06b86242005-10-20 16:46:23 +0200544
Jens Axboe98170642006-07-28 09:23:08 +0200545 elv_rqhash_reposition(q, rq);
546 elv_rqhash_del(q, next);
547
548 q->nr_sorted--;
Tejun Heo06b86242005-10-20 16:46:23 +0200549 q->last_merge = rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550}
551
Divyesh Shah812d4022010-04-08 21:14:23 -0700552void elv_bio_merged(struct request_queue *q, struct request *rq,
553 struct bio *bio)
554{
555 struct elevator_queue *e = q->elevator;
556
557 if (e->ops->elevator_bio_merged_fn)
558 e->ops->elevator_bio_merged_fn(q, rq, bio);
559}
560
Jens Axboe165125e2007-07-24 09:28:11 +0200561void elv_requeue_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563 /*
564 * it already went through dequeue, we need to decrement the
565 * in_flight count again
566 */
Tejun Heo8922e162005-10-20 16:23:44 +0200567 if (blk_account_rq(rq)) {
Jens Axboe0a7ae2f2009-05-20 08:54:31 +0200568 q->in_flight[rq_is_sync(rq)]--;
Christoph Hellwig33659eb2010-08-07 18:17:56 +0200569 if (rq->cmd_flags & REQ_SORTED)
Jens Axboecad97512007-01-14 22:26:09 +1100570 elv_deactivate_rq(q, rq);
Tejun Heo8922e162005-10-20 16:23:44 +0200571 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572
Jens Axboe4aff5e22006-08-10 08:44:47 +0200573 rq->cmd_flags &= ~REQ_STARTED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574
Tejun Heo30e96562006-02-08 01:01:31 -0800575 elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576}
577
Jerome Marchand26308ea2009-03-27 10:31:51 +0100578void elv_drain_elevator(struct request_queue *q)
Tejun Heo15853af2005-11-10 08:52:05 +0100579{
580 static int printed;
581 while (q->elevator->ops->elevator_dispatch_fn(q, 1))
582 ;
583 if (q->nr_sorted == 0)
584 return;
585 if (printed++ < 10) {
586 printk(KERN_ERR "%s: forced dispatching is broken "
587 "(nr_sorted=%u), please report this\n",
588 q->elevator->elevator_type->elevator_name, q->nr_sorted);
589 }
590}
591
Jens Axboe6c7e8ce2009-03-27 10:30:47 +0100592/*
593 * Call with queue lock held, interrupts disabled
594 */
Jens Axboef600abe2009-04-08 14:22:01 +0200595void elv_quiesce_start(struct request_queue *q)
Jens Axboe6c7e8ce2009-03-27 10:30:47 +0100596{
Martin K. Petersencd43e262009-05-22 17:17:52 -0400597 if (!q->elevator)
598 return;
599
Jens Axboe6c7e8ce2009-03-27 10:30:47 +0100600 queue_flag_set(QUEUE_FLAG_ELVSWITCH, q);
601
602 /*
603 * make sure we don't have any requests in flight
604 */
605 elv_drain_elevator(q);
606 while (q->rq.elvpriv) {
Tejun Heoa7f55792009-04-23 11:05:17 +0900607 __blk_run_queue(q);
Jens Axboe6c7e8ce2009-03-27 10:30:47 +0100608 spin_unlock_irq(q->queue_lock);
609 msleep(10);
610 spin_lock_irq(q->queue_lock);
611 elv_drain_elevator(q);
612 }
613}
614
Jens Axboef600abe2009-04-08 14:22:01 +0200615void elv_quiesce_end(struct request_queue *q)
Jens Axboe6c7e8ce2009-03-27 10:30:47 +0100616{
617 queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
618}
619
Jens Axboe165125e2007-07-24 09:28:11 +0200620void elv_insert(struct request_queue *q, struct request *rq, int where)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621{
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +0100622 trace_block_rq_insert(q, rq);
Jens Axboe2056a782006-03-23 20:00:26 +0100623
Linus Torvalds1da177e2005-04-16 15:20:36 -0700624 rq->q = q;
625
Tejun Heo8922e162005-10-20 16:23:44 +0200626 switch (where) {
Tejun Heo28e7d182010-09-03 11:56:16 +0200627 case ELEVATOR_INSERT_REQUEUE:
Tejun Heo8922e162005-10-20 16:23:44 +0200628 case ELEVATOR_INSERT_FRONT:
Jens Axboe4aff5e22006-08-10 08:44:47 +0200629 rq->cmd_flags |= REQ_SOFTBARRIER;
Tejun Heo8922e162005-10-20 16:23:44 +0200630 list_add(&rq->queuelist, &q->queue_head);
631 break;
632
633 case ELEVATOR_INSERT_BACK:
Jens Axboe4aff5e22006-08-10 08:44:47 +0200634 rq->cmd_flags |= REQ_SOFTBARRIER;
Tejun Heo15853af2005-11-10 08:52:05 +0100635 elv_drain_elevator(q);
Tejun Heo8922e162005-10-20 16:23:44 +0200636 list_add_tail(&rq->queuelist, &q->queue_head);
637 /*
638 * We kick the queue here for the following reasons.
639 * - The elevator might have returned NULL previously
640 * to delay requests and returned them now. As the
641 * queue wasn't empty before this request, ll_rw_blk
642 * won't run the queue on return, resulting in hang.
643 * - Usually, back inserted requests won't be merged
644 * with anything. There's no point in delaying queue
645 * processing.
646 */
Tejun Heoa7f55792009-04-23 11:05:17 +0900647 __blk_run_queue(q);
Tejun Heo8922e162005-10-20 16:23:44 +0200648 break;
649
650 case ELEVATOR_INSERT_SORT:
Christoph Hellwig33659eb2010-08-07 18:17:56 +0200651 BUG_ON(rq->cmd_type != REQ_TYPE_FS &&
652 !(rq->cmd_flags & REQ_DISCARD));
Jens Axboe4aff5e22006-08-10 08:44:47 +0200653 rq->cmd_flags |= REQ_SORTED;
Tejun Heo15853af2005-11-10 08:52:05 +0100654 q->nr_sorted++;
Jens Axboe98170642006-07-28 09:23:08 +0200655 if (rq_mergeable(rq)) {
656 elv_rqhash_add(q, rq);
657 if (!q->last_merge)
658 q->last_merge = rq;
659 }
660
Tejun Heoca235092005-11-01 17:23:49 +0900661 /*
662 * Some ioscheds (cfq) run q->request_fn directly, so
663 * rq cannot be accessed after calling
664 * elevator_add_req_fn.
665 */
666 q->elevator->ops->elevator_add_req_fn(q, rq);
Tejun Heo8922e162005-10-20 16:23:44 +0200667 break;
668
Tejun Heoae1b1532011-01-25 12:43:54 +0100669 case ELEVATOR_INSERT_FLUSH:
670 rq->cmd_flags |= REQ_SOFTBARRIER;
671 blk_insert_flush(rq);
672 break;
Tejun Heo8922e162005-10-20 16:23:44 +0200673 default:
674 printk(KERN_ERR "%s: bad insertion point %d\n",
Harvey Harrison24c03d42008-05-01 04:35:17 -0700675 __func__, where);
Tejun Heo8922e162005-10-20 16:23:44 +0200676 BUG();
677 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678}
679
Jens Axboe7eaceac2011-03-10 08:52:07 +0100680void __elv_add_request(struct request_queue *q, struct request *rq, int where)
Tejun Heo30e96562006-02-08 01:01:31 -0800681{
Jens Axboe73c10102011-03-08 13:19:51 +0100682 BUG_ON(rq->cmd_flags & REQ_ON_PLUG);
683
Christoph Hellwig02e031c2010-11-10 14:54:09 +0100684 if (rq->cmd_flags & REQ_SOFTBARRIER) {
Tejun Heo28e7d182010-09-03 11:56:16 +0200685 /* barriers are scheduling boundary, update end_sector */
Christoph Hellwig33659eb2010-08-07 18:17:56 +0200686 if (rq->cmd_type == REQ_TYPE_FS ||
687 (rq->cmd_flags & REQ_DISCARD)) {
Tejun Heo30e96562006-02-08 01:01:31 -0800688 q->end_sector = rq_end_sector(rq);
689 q->boundary_rq = rq;
690 }
Jens Axboe4eb166d2008-02-01 00:37:27 +0100691 } else if (!(rq->cmd_flags & REQ_ELVPRIV) &&
692 where == ELEVATOR_INSERT_SORT)
Tejun Heo30e96562006-02-08 01:01:31 -0800693 where = ELEVATOR_INSERT_BACK;
694
Tejun Heo30e96562006-02-08 01:01:31 -0800695 elv_insert(q, rq, where);
696}
Jens Axboe2e662b62006-07-13 11:55:04 +0200697EXPORT_SYMBOL(__elv_add_request);
698
Jens Axboe7eaceac2011-03-10 08:52:07 +0100699void elv_add_request(struct request_queue *q, struct request *rq, int where)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700{
701 unsigned long flags;
702
703 spin_lock_irqsave(q->queue_lock, flags);
Jens Axboe7eaceac2011-03-10 08:52:07 +0100704 __elv_add_request(q, rq, where);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 spin_unlock_irqrestore(q->queue_lock, flags);
706}
Jens Axboe2e662b62006-07-13 11:55:04 +0200707EXPORT_SYMBOL(elv_add_request);
708
Jens Axboe165125e2007-07-24 09:28:11 +0200709struct request *elv_latter_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710{
Jens Axboeb374d182008-10-31 10:05:07 +0100711 struct elevator_queue *e = q->elevator;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700712
713 if (e->ops->elevator_latter_req_fn)
714 return e->ops->elevator_latter_req_fn(q, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715 return NULL;
716}
717
Jens Axboe165125e2007-07-24 09:28:11 +0200718struct request *elv_former_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719{
Jens Axboeb374d182008-10-31 10:05:07 +0100720 struct elevator_queue *e = q->elevator;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721
722 if (e->ops->elevator_former_req_fn)
723 return e->ops->elevator_former_req_fn(q, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724 return NULL;
725}
726
Jens Axboe165125e2007-07-24 09:28:11 +0200727int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728{
Jens Axboeb374d182008-10-31 10:05:07 +0100729 struct elevator_queue *e = q->elevator;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730
731 if (e->ops->elevator_set_req_fn)
Jens Axboecb78b282006-07-28 09:32:57 +0200732 return e->ops->elevator_set_req_fn(q, rq, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733
Mike Snitzerc1867942011-02-11 11:08:00 +0100734 rq->elevator_private[0] = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700735 return 0;
736}
737
Jens Axboe165125e2007-07-24 09:28:11 +0200738void elv_put_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739{
Jens Axboeb374d182008-10-31 10:05:07 +0100740 struct elevator_queue *e = q->elevator;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741
742 if (e->ops->elevator_put_req_fn)
Jens Axboebb37b942006-12-01 10:42:33 +0100743 e->ops->elevator_put_req_fn(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744}
745
Jens Axboe165125e2007-07-24 09:28:11 +0200746int elv_may_queue(struct request_queue *q, int rw)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747{
Jens Axboeb374d182008-10-31 10:05:07 +0100748 struct elevator_queue *e = q->elevator;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700749
750 if (e->ops->elevator_may_queue_fn)
Jens Axboecb78b282006-07-28 09:32:57 +0200751 return e->ops->elevator_may_queue_fn(q, rw);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752
753 return ELV_MQUEUE_MAY;
754}
755
Mike Anderson11914a52008-09-13 20:31:27 +0200756void elv_abort_queue(struct request_queue *q)
757{
758 struct request *rq;
759
Tejun Heoae1b1532011-01-25 12:43:54 +0100760 blk_abort_flushes(q);
761
Mike Anderson11914a52008-09-13 20:31:27 +0200762 while (!list_empty(&q->queue_head)) {
763 rq = list_entry_rq(q->queue_head.next);
764 rq->cmd_flags |= REQ_QUIET;
Arnaldo Carvalho de Melo5f3ea372008-10-30 08:34:33 +0100765 trace_block_rq_abort(q, rq);
Kiyoshi Ueda53c663c2009-06-02 08:44:01 +0200766 /*
767 * Mark this request as started so we don't trigger
768 * any debug logic in the end I/O path.
769 */
770 blk_start_request(rq);
Tejun Heo40cbbb72009-04-23 11:05:19 +0900771 __blk_end_request_all(rq, -EIO);
Mike Anderson11914a52008-09-13 20:31:27 +0200772 }
773}
774EXPORT_SYMBOL(elv_abort_queue);
775
Jens Axboe165125e2007-07-24 09:28:11 +0200776void elv_completed_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777{
Jens Axboeb374d182008-10-31 10:05:07 +0100778 struct elevator_queue *e = q->elevator;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779
780 /*
781 * request is released from the driver, io must be done
782 */
Tejun Heo8922e162005-10-20 16:23:44 +0200783 if (blk_account_rq(rq)) {
Jens Axboe0a7ae2f2009-05-20 08:54:31 +0200784 q->in_flight[rq_is_sync(rq)]--;
Christoph Hellwig33659eb2010-08-07 18:17:56 +0200785 if ((rq->cmd_flags & REQ_SORTED) &&
786 e->ops->elevator_completed_req_fn)
Tejun Heo1bc691d2006-01-12 15:39:26 +0100787 e->ops->elevator_completed_req_fn(q, rq);
788 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789}
790
Al Viro3d1ab402006-03-18 18:35:43 -0500791#define to_elv(atr) container_of((atr), struct elv_fs_entry, attr)
792
793static ssize_t
794elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
795{
Al Viro3d1ab402006-03-18 18:35:43 -0500796 struct elv_fs_entry *entry = to_elv(attr);
Jens Axboeb374d182008-10-31 10:05:07 +0100797 struct elevator_queue *e;
Al Viro3d1ab402006-03-18 18:35:43 -0500798 ssize_t error;
799
800 if (!entry->show)
801 return -EIO;
802
Jens Axboeb374d182008-10-31 10:05:07 +0100803 e = container_of(kobj, struct elevator_queue, kobj);
Al Viro3d1ab402006-03-18 18:35:43 -0500804 mutex_lock(&e->sysfs_lock);
805 error = e->ops ? entry->show(e, page) : -ENOENT;
806 mutex_unlock(&e->sysfs_lock);
807 return error;
808}
809
810static ssize_t
811elv_attr_store(struct kobject *kobj, struct attribute *attr,
812 const char *page, size_t length)
813{
Al Viro3d1ab402006-03-18 18:35:43 -0500814 struct elv_fs_entry *entry = to_elv(attr);
Jens Axboeb374d182008-10-31 10:05:07 +0100815 struct elevator_queue *e;
Al Viro3d1ab402006-03-18 18:35:43 -0500816 ssize_t error;
817
818 if (!entry->store)
819 return -EIO;
820
Jens Axboeb374d182008-10-31 10:05:07 +0100821 e = container_of(kobj, struct elevator_queue, kobj);
Al Viro3d1ab402006-03-18 18:35:43 -0500822 mutex_lock(&e->sysfs_lock);
823 error = e->ops ? entry->store(e, page, length) : -ENOENT;
824 mutex_unlock(&e->sysfs_lock);
825 return error;
826}
827
Emese Revfy52cf25d2010-01-19 02:58:23 +0100828static const struct sysfs_ops elv_sysfs_ops = {
Al Viro3d1ab402006-03-18 18:35:43 -0500829 .show = elv_attr_show,
830 .store = elv_attr_store,
831};
832
833static struct kobj_type elv_ktype = {
834 .sysfs_ops = &elv_sysfs_ops,
835 .release = elevator_release,
836};
837
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838int elv_register_queue(struct request_queue *q)
839{
Jens Axboeb374d182008-10-31 10:05:07 +0100840 struct elevator_queue *e = q->elevator;
Al Viro3d1ab402006-03-18 18:35:43 -0500841 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842
Greg Kroah-Hartmanb2d6db52007-12-17 23:05:35 -0700843 error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched");
Al Viro3d1ab402006-03-18 18:35:43 -0500844 if (!error) {
Al Viroe572ec72006-03-18 22:27:18 -0500845 struct elv_fs_entry *attr = e->elevator_type->elevator_attrs;
Al Viro3d1ab402006-03-18 18:35:43 -0500846 if (attr) {
Al Viroe572ec72006-03-18 22:27:18 -0500847 while (attr->attr.name) {
848 if (sysfs_create_file(&e->kobj, &attr->attr))
Al Viro3d1ab402006-03-18 18:35:43 -0500849 break;
Al Viroe572ec72006-03-18 22:27:18 -0500850 attr++;
Al Viro3d1ab402006-03-18 18:35:43 -0500851 }
852 }
853 kobject_uevent(&e->kobj, KOBJ_ADD);
Jens Axboe430c62f2010-10-07 09:35:16 +0200854 e->registered = 1;
Al Viro3d1ab402006-03-18 18:35:43 -0500855 }
856 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857}
Mike Snitzer01effb02010-05-11 08:57:42 +0200858EXPORT_SYMBOL(elv_register_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700859
Jens Axboeb374d182008-10-31 10:05:07 +0100860static void __elv_unregister_queue(struct elevator_queue *e)
Jens Axboebc1c1162006-06-08 08:49:06 +0200861{
862 kobject_uevent(&e->kobj, KOBJ_REMOVE);
863 kobject_del(&e->kobj);
Jens Axboe430c62f2010-10-07 09:35:16 +0200864 e->registered = 0;
Jens Axboebc1c1162006-06-08 08:49:06 +0200865}
866
Linus Torvalds1da177e2005-04-16 15:20:36 -0700867void elv_unregister_queue(struct request_queue *q)
868{
Jens Axboebc1c1162006-06-08 08:49:06 +0200869 if (q)
870 __elv_unregister_queue(q->elevator);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700871}
Mike Snitzer01effb02010-05-11 08:57:42 +0200872EXPORT_SYMBOL(elv_unregister_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700873
Adrian Bunk2fdd82b2007-12-12 18:51:56 +0100874void elv_register(struct elevator_type *e)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875{
Thibaut VARENE1ffb96c2007-03-15 12:59:19 +0100876 char *def = "";
Jens Axboe2a12dcd2007-04-26 14:41:53 +0200877
878 spin_lock(&elv_list_lock);
Eric Sesterhennce524492006-03-24 18:43:26 +0100879 BUG_ON(elevator_find(e->elevator_name));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700880 list_add_tail(&e->list, &elv_list);
Jens Axboe2a12dcd2007-04-26 14:41:53 +0200881 spin_unlock(&elv_list_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882
Nate Diller5f003972006-01-24 10:07:58 +0100883 if (!strcmp(e->elevator_name, chosen_elevator) ||
884 (!*chosen_elevator &&
885 !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED)))
Thibaut VARENE1ffb96c2007-03-15 12:59:19 +0100886 def = " (default)";
887
Jens Axboe4eb166d2008-02-01 00:37:27 +0100888 printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name,
889 def);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700890}
891EXPORT_SYMBOL_GPL(elv_register);
892
893void elv_unregister(struct elevator_type *e)
894{
Christoph Hellwig83521d32005-10-30 15:01:39 -0800895 struct task_struct *g, *p;
896
897 /*
898 * Iterate every thread in the process to remove the io contexts.
899 */
Al Viroe17a9482006-03-18 13:21:20 -0500900 if (e->ops.trim) {
901 read_lock(&tasklist_lock);
902 do_each_thread(g, p) {
903 task_lock(p);
Oleg Nesterov2d8f6132006-08-22 21:22:13 +0400904 if (p->io_context)
905 e->ops.trim(p->io_context);
Al Viroe17a9482006-03-18 13:21:20 -0500906 task_unlock(p);
907 } while_each_thread(g, p);
908 read_unlock(&tasklist_lock);
909 }
Christoph Hellwig83521d32005-10-30 15:01:39 -0800910
Jens Axboe2a12dcd2007-04-26 14:41:53 +0200911 spin_lock(&elv_list_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700912 list_del_init(&e->list);
Jens Axboe2a12dcd2007-04-26 14:41:53 +0200913 spin_unlock(&elv_list_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914}
915EXPORT_SYMBOL_GPL(elv_unregister);
916
917/*
918 * switch to new_e io scheduler. be careful not to introduce deadlocks -
919 * we don't free the old io scheduler, before we have allocated what we
920 * need for the new one. this way we have a chance of going back to the old
Tejun Heocb98fc82005-10-28 08:29:39 +0200921 * one, if the new one fails init for some reason.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922 */
Jens Axboe165125e2007-07-24 09:28:11 +0200923static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924{
Jens Axboeb374d182008-10-31 10:05:07 +0100925 struct elevator_queue *old_elevator, *e;
Jens Axboebc1c1162006-06-08 08:49:06 +0200926 void *data;
Jens Axboe5dd531a2010-08-23 13:52:19 +0200927 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700928
Tejun Heocb98fc82005-10-28 08:29:39 +0200929 /*
930 * Allocate new elevator
931 */
Jens Axboeb5deef92006-07-19 23:39:40 +0200932 e = elevator_alloc(q, new_e);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700933 if (!e)
Jens Axboe5dd531a2010-08-23 13:52:19 +0200934 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700935
Jens Axboebc1c1162006-06-08 08:49:06 +0200936 data = elevator_init_queue(q, e);
937 if (!data) {
938 kobject_put(&e->kobj);
Jens Axboe5dd531a2010-08-23 13:52:19 +0200939 return -ENOMEM;
Jens Axboebc1c1162006-06-08 08:49:06 +0200940 }
941
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942 /*
Tejun Heocb98fc82005-10-28 08:29:39 +0200943 * Turn on BYPASS and drain all requests w/ elevator private data
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944 */
Tejun Heocb98fc82005-10-28 08:29:39 +0200945 spin_lock_irq(q->queue_lock);
Jens Axboef600abe2009-04-08 14:22:01 +0200946 elv_quiesce_start(q);
Tejun Heocb98fc82005-10-28 08:29:39 +0200947
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948 /*
Jens Axboebc1c1162006-06-08 08:49:06 +0200949 * Remember old elevator.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700950 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951 old_elevator = q->elevator;
952
953 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954 * attach and start new elevator
955 */
Jens Axboebc1c1162006-06-08 08:49:06 +0200956 elevator_attach(q, e, data);
957
958 spin_unlock_irq(q->queue_lock);
959
Jens Axboe430c62f2010-10-07 09:35:16 +0200960 if (old_elevator->registered) {
961 __elv_unregister_queue(old_elevator);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700962
Jens Axboe430c62f2010-10-07 09:35:16 +0200963 err = elv_register_queue(q);
964 if (err)
965 goto fail_register;
966 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700967
968 /*
Tejun Heocb98fc82005-10-28 08:29:39 +0200969 * finally exit old elevator and turn off BYPASS.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700970 */
971 elevator_exit(old_elevator);
Nick Piggin75ad23b2008-04-29 14:48:33 +0200972 spin_lock_irq(q->queue_lock);
Jens Axboef600abe2009-04-08 14:22:01 +0200973 elv_quiesce_end(q);
Nick Piggin75ad23b2008-04-29 14:48:33 +0200974 spin_unlock_irq(q->queue_lock);
975
Alan D. Brunelle4722dc52008-05-27 14:55:00 +0200976 blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name);
977
Jens Axboe5dd531a2010-08-23 13:52:19 +0200978 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700979
980fail_register:
981 /*
982 * switch failed, exit the new io scheduler and reattach the old
983 * one again (along with re-adding the sysfs dir)
984 */
985 elevator_exit(e);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700986 q->elevator = old_elevator;
987 elv_register_queue(q);
Nick Piggin75ad23b2008-04-29 14:48:33 +0200988
989 spin_lock_irq(q->queue_lock);
990 queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
991 spin_unlock_irq(q->queue_lock);
992
Jens Axboe5dd531a2010-08-23 13:52:19 +0200993 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700994}
995
Jens Axboe5dd531a2010-08-23 13:52:19 +0200996/*
997 * Switch this queue to the given IO scheduler.
998 */
999int elevator_change(struct request_queue *q, const char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000{
1001 char elevator_name[ELV_NAME_MAX];
1002 struct elevator_type *e;
1003
Martin K. Petersencd43e262009-05-22 17:17:52 -04001004 if (!q->elevator)
Jens Axboe5dd531a2010-08-23 13:52:19 +02001005 return -ENXIO;
Martin K. Petersencd43e262009-05-22 17:17:52 -04001006
Li Zefanee2e9922008-10-14 08:49:56 +02001007 strlcpy(elevator_name, name, sizeof(elevator_name));
KOSAKI Motohiro8c279592009-10-09 08:48:08 +02001008 e = elevator_get(strstrip(elevator_name));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001009 if (!e) {
1010 printk(KERN_ERR "elevator: type %s not found\n", elevator_name);
1011 return -EINVAL;
1012 }
1013
Nate Diller2ca7d932005-10-30 15:02:24 -08001014 if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) {
1015 elevator_put(e);
Jens Axboe5dd531a2010-08-23 13:52:19 +02001016 return 0;
Nate Diller2ca7d932005-10-30 15:02:24 -08001017 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018
Jens Axboe5dd531a2010-08-23 13:52:19 +02001019 return elevator_switch(q, e);
1020}
1021EXPORT_SYMBOL(elevator_change);
1022
1023ssize_t elv_iosched_store(struct request_queue *q, const char *name,
1024 size_t count)
1025{
1026 int ret;
1027
1028 if (!q->elevator)
1029 return count;
1030
1031 ret = elevator_change(q, name);
1032 if (!ret)
1033 return count;
1034
1035 printk(KERN_ERR "elevator: switch to %s failed\n", name);
1036 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001037}
1038
Jens Axboe165125e2007-07-24 09:28:11 +02001039ssize_t elv_iosched_show(struct request_queue *q, char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040{
Jens Axboeb374d182008-10-31 10:05:07 +01001041 struct elevator_queue *e = q->elevator;
Martin K. Petersencd43e262009-05-22 17:17:52 -04001042 struct elevator_type *elv;
Matthias Kaehlcke70cee262007-07-10 12:26:24 +02001043 struct elevator_type *__e;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044 int len = 0;
1045
Mike Snitzere36f7242010-05-24 09:07:32 +02001046 if (!q->elevator || !blk_queue_stackable(q))
Martin K. Petersencd43e262009-05-22 17:17:52 -04001047 return sprintf(name, "none\n");
1048
1049 elv = e->elevator_type;
1050
Jens Axboe2a12dcd2007-04-26 14:41:53 +02001051 spin_lock(&elv_list_lock);
Matthias Kaehlcke70cee262007-07-10 12:26:24 +02001052 list_for_each_entry(__e, &elv_list, list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001053 if (!strcmp(elv->elevator_name, __e->elevator_name))
1054 len += sprintf(name+len, "[%s] ", elv->elevator_name);
1055 else
1056 len += sprintf(name+len, "%s ", __e->elevator_name);
1057 }
Jens Axboe2a12dcd2007-04-26 14:41:53 +02001058 spin_unlock(&elv_list_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001059
1060 len += sprintf(len+name, "\n");
1061 return len;
1062}
1063
Jens Axboe165125e2007-07-24 09:28:11 +02001064struct request *elv_rb_former_request(struct request_queue *q,
1065 struct request *rq)
Jens Axboe2e662b62006-07-13 11:55:04 +02001066{
1067 struct rb_node *rbprev = rb_prev(&rq->rb_node);
1068
1069 if (rbprev)
1070 return rb_entry_rq(rbprev);
1071
1072 return NULL;
1073}
Jens Axboe2e662b62006-07-13 11:55:04 +02001074EXPORT_SYMBOL(elv_rb_former_request);
1075
Jens Axboe165125e2007-07-24 09:28:11 +02001076struct request *elv_rb_latter_request(struct request_queue *q,
1077 struct request *rq)
Jens Axboe2e662b62006-07-13 11:55:04 +02001078{
1079 struct rb_node *rbnext = rb_next(&rq->rb_node);
1080
1081 if (rbnext)
1082 return rb_entry_rq(rbnext);
1083
1084 return NULL;
1085}
Jens Axboe2e662b62006-07-13 11:55:04 +02001086EXPORT_SYMBOL(elv_rb_latter_request);