Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2 | * Block device elevator/IO-scheduler. |
| 3 | * |
| 4 | * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE |
| 5 | * |
| 6 | * 30042000 Jens Axboe <axboe@suse.de> : |
| 7 | * |
| 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> |
| 30 | #include <linux/config.h> |
| 31 | #include <linux/module.h> |
| 32 | #include <linux/slab.h> |
| 33 | #include <linux/init.h> |
| 34 | #include <linux/compiler.h> |
Tejun Heo | cb98fc8 | 2005-10-28 08:29:39 +0200 | [diff] [blame] | 35 | #include <linux/delay.h> |
Jens Axboe | 2056a78 | 2006-03-23 20:00:26 +0100 | [diff] [blame] | 36 | #include <linux/blktrace_api.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 37 | |
| 38 | #include <asm/uaccess.h> |
| 39 | |
| 40 | static DEFINE_SPINLOCK(elv_list_lock); |
| 41 | static LIST_HEAD(elv_list); |
| 42 | |
| 43 | /* |
| 44 | * can we safely merge with this request? |
| 45 | */ |
| 46 | inline int elv_rq_merge_ok(struct request *rq, struct bio *bio) |
| 47 | { |
| 48 | if (!rq_mergeable(rq)) |
| 49 | return 0; |
| 50 | |
| 51 | /* |
| 52 | * different data direction or already started, don't merge |
| 53 | */ |
| 54 | if (bio_data_dir(bio) != rq_data_dir(rq)) |
| 55 | return 0; |
| 56 | |
| 57 | /* |
| 58 | * same device and no special stuff set, merge is ok |
| 59 | */ |
| 60 | if (rq->rq_disk == bio->bi_bdev->bd_disk && |
| 61 | !rq->waiting && !rq->special) |
| 62 | return 1; |
| 63 | |
| 64 | return 0; |
| 65 | } |
| 66 | EXPORT_SYMBOL(elv_rq_merge_ok); |
| 67 | |
Coywolf Qi Hunt | 769db45 | 2005-12-28 10:55:49 +0100 | [diff] [blame] | 68 | static inline int elv_try_merge(struct request *__rq, struct bio *bio) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 69 | { |
| 70 | int ret = ELEVATOR_NO_MERGE; |
| 71 | |
| 72 | /* |
| 73 | * we can merge and sequence is ok, check if it's possible |
| 74 | */ |
| 75 | if (elv_rq_merge_ok(__rq, bio)) { |
| 76 | if (__rq->sector + __rq->nr_sectors == bio->bi_sector) |
| 77 | ret = ELEVATOR_BACK_MERGE; |
| 78 | else if (__rq->sector - bio_sectors(bio) == bio->bi_sector) |
| 79 | ret = ELEVATOR_FRONT_MERGE; |
| 80 | } |
| 81 | |
| 82 | return ret; |
| 83 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 84 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 85 | static struct elevator_type *elevator_find(const char *name) |
| 86 | { |
| 87 | struct elevator_type *e = NULL; |
| 88 | struct list_head *entry; |
| 89 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 90 | list_for_each(entry, &elv_list) { |
| 91 | struct elevator_type *__e; |
| 92 | |
| 93 | __e = list_entry(entry, struct elevator_type, list); |
| 94 | |
| 95 | if (!strcmp(__e->elevator_name, name)) { |
| 96 | e = __e; |
| 97 | break; |
| 98 | } |
| 99 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 100 | |
| 101 | return e; |
| 102 | } |
| 103 | |
| 104 | static void elevator_put(struct elevator_type *e) |
| 105 | { |
| 106 | module_put(e->elevator_owner); |
| 107 | } |
| 108 | |
| 109 | static struct elevator_type *elevator_get(const char *name) |
| 110 | { |
Tejun Heo | 2824bc93 | 2005-10-20 10:56:41 +0200 | [diff] [blame] | 111 | struct elevator_type *e; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 112 | |
Tejun Heo | 2824bc93 | 2005-10-20 10:56:41 +0200 | [diff] [blame] | 113 | spin_lock_irq(&elv_list_lock); |
| 114 | |
| 115 | e = elevator_find(name); |
| 116 | if (e && !try_module_get(e->elevator_owner)) |
| 117 | e = NULL; |
| 118 | |
| 119 | spin_unlock_irq(&elv_list_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 120 | |
| 121 | return e; |
| 122 | } |
| 123 | |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 124 | static int elevator_attach(request_queue_t *q, struct elevator_queue *eq) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 125 | { |
| 126 | int ret = 0; |
| 127 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 128 | q->elevator = eq; |
| 129 | |
| 130 | if (eq->ops->elevator_init_fn) |
| 131 | ret = eq->ops->elevator_init_fn(q, eq); |
| 132 | |
| 133 | return ret; |
| 134 | } |
| 135 | |
| 136 | static char chosen_elevator[16]; |
| 137 | |
Nate Diller | 5f00397 | 2006-01-24 10:07:58 +0100 | [diff] [blame] | 138 | static int __init elevator_setup(char *str) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 139 | { |
Chuck Ebbert | 752a3b7 | 2006-01-16 09:47:37 +0100 | [diff] [blame] | 140 | /* |
| 141 | * Be backwards-compatible with previous kernels, so users |
| 142 | * won't get the wrong elevator. |
| 143 | */ |
Nate Diller | 5f00397 | 2006-01-24 10:07:58 +0100 | [diff] [blame] | 144 | if (!strcmp(str, "as")) |
Chuck Ebbert | 752a3b7 | 2006-01-16 09:47:37 +0100 | [diff] [blame] | 145 | strcpy(chosen_elevator, "anticipatory"); |
Zachary Amsden | cff3ba2 | 2005-11-09 13:24:20 +0100 | [diff] [blame] | 146 | else |
Nate Diller | 5f00397 | 2006-01-24 10:07:58 +0100 | [diff] [blame] | 147 | strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
OGAWA Hirofumi | 9b41046 | 2006-03-31 02:30:33 -0800 | [diff] [blame^] | 148 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 149 | } |
| 150 | |
| 151 | __setup("elevator=", elevator_setup); |
| 152 | |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 153 | static struct kobj_type elv_ktype; |
| 154 | |
| 155 | static elevator_t *elevator_alloc(struct elevator_type *e) |
| 156 | { |
| 157 | elevator_t *eq = kmalloc(sizeof(elevator_t), GFP_KERNEL); |
| 158 | if (eq) { |
| 159 | memset(eq, 0, sizeof(*eq)); |
| 160 | eq->ops = &e->ops; |
| 161 | eq->elevator_type = e; |
| 162 | kobject_init(&eq->kobj); |
| 163 | snprintf(eq->kobj.name, KOBJ_NAME_LEN, "%s", "iosched"); |
| 164 | eq->kobj.ktype = &elv_ktype; |
| 165 | mutex_init(&eq->sysfs_lock); |
| 166 | } else { |
| 167 | elevator_put(e); |
| 168 | } |
| 169 | return eq; |
| 170 | } |
| 171 | |
| 172 | static void elevator_release(struct kobject *kobj) |
| 173 | { |
| 174 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
| 175 | elevator_put(e->elevator_type); |
| 176 | kfree(e); |
| 177 | } |
| 178 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 179 | int elevator_init(request_queue_t *q, char *name) |
| 180 | { |
| 181 | struct elevator_type *e = NULL; |
| 182 | struct elevator_queue *eq; |
| 183 | int ret = 0; |
| 184 | |
Tejun Heo | cb98fc8 | 2005-10-28 08:29:39 +0200 | [diff] [blame] | 185 | INIT_LIST_HEAD(&q->queue_head); |
| 186 | q->last_merge = NULL; |
| 187 | q->end_sector = 0; |
| 188 | q->boundary_rq = NULL; |
Tejun Heo | cb98fc8 | 2005-10-28 08:29:39 +0200 | [diff] [blame] | 189 | |
Nate Diller | 5f00397 | 2006-01-24 10:07:58 +0100 | [diff] [blame] | 190 | if (name && !(e = elevator_get(name))) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 191 | return -EINVAL; |
| 192 | |
Nate Diller | 248d5ca | 2006-01-24 10:09:14 +0100 | [diff] [blame] | 193 | if (!e && *chosen_elevator && !(e = elevator_get(chosen_elevator))) |
| 194 | printk("I/O scheduler %s not found\n", chosen_elevator); |
| 195 | |
| 196 | if (!e && !(e = elevator_get(CONFIG_DEFAULT_IOSCHED))) { |
| 197 | printk("Default I/O scheduler not found, using no-op\n"); |
| 198 | e = elevator_get("noop"); |
Nate Diller | 5f00397 | 2006-01-24 10:07:58 +0100 | [diff] [blame] | 199 | } |
| 200 | |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 201 | eq = elevator_alloc(e); |
| 202 | if (!eq) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 203 | return -ENOMEM; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 204 | |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 205 | ret = elevator_attach(q, eq); |
| 206 | if (ret) |
| 207 | kobject_put(&eq->kobj); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 208 | |
| 209 | return ret; |
| 210 | } |
| 211 | |
| 212 | void elevator_exit(elevator_t *e) |
| 213 | { |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 214 | mutex_lock(&e->sysfs_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 215 | if (e->ops->elevator_exit_fn) |
| 216 | e->ops->elevator_exit_fn(e); |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 217 | e->ops = NULL; |
| 218 | mutex_unlock(&e->sysfs_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 219 | |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 220 | kobject_put(&e->kobj); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 221 | } |
| 222 | |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 223 | /* |
| 224 | * Insert rq into dispatch queue of q. Queue lock must be held on |
| 225 | * entry. If sort != 0, rq is sort-inserted; otherwise, rq will be |
| 226 | * appended to the dispatch queue. To be used by specific elevators. |
| 227 | */ |
Jens Axboe | 1b47f53 | 2005-10-20 16:37:00 +0200 | [diff] [blame] | 228 | void elv_dispatch_sort(request_queue_t *q, struct request *rq) |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 229 | { |
| 230 | sector_t boundary; |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 231 | struct list_head *entry; |
| 232 | |
Tejun Heo | 06b8624 | 2005-10-20 16:46:23 +0200 | [diff] [blame] | 233 | if (q->last_merge == rq) |
| 234 | q->last_merge = NULL; |
Tejun Heo | 15853af | 2005-11-10 08:52:05 +0100 | [diff] [blame] | 235 | q->nr_sorted--; |
Tejun Heo | 06b8624 | 2005-10-20 16:46:23 +0200 | [diff] [blame] | 236 | |
Jens Axboe | 1b47f53 | 2005-10-20 16:37:00 +0200 | [diff] [blame] | 237 | boundary = q->end_sector; |
Tejun Heo | cb19833 | 2005-10-24 08:35:58 +0200 | [diff] [blame] | 238 | |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 239 | list_for_each_prev(entry, &q->queue_head) { |
| 240 | struct request *pos = list_entry_rq(entry); |
| 241 | |
| 242 | if (pos->flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED)) |
| 243 | break; |
| 244 | if (rq->sector >= boundary) { |
| 245 | if (pos->sector < boundary) |
| 246 | continue; |
| 247 | } else { |
| 248 | if (pos->sector >= boundary) |
| 249 | break; |
| 250 | } |
| 251 | if (rq->sector >= pos->sector) |
| 252 | break; |
| 253 | } |
| 254 | |
| 255 | list_add(&rq->queuelist, entry); |
| 256 | } |
| 257 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 258 | int elv_merge(request_queue_t *q, struct request **req, struct bio *bio) |
| 259 | { |
| 260 | elevator_t *e = q->elevator; |
Tejun Heo | 06b8624 | 2005-10-20 16:46:23 +0200 | [diff] [blame] | 261 | int ret; |
| 262 | |
| 263 | if (q->last_merge) { |
| 264 | ret = elv_try_merge(q->last_merge, bio); |
| 265 | if (ret != ELEVATOR_NO_MERGE) { |
| 266 | *req = q->last_merge; |
| 267 | return ret; |
| 268 | } |
| 269 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 270 | |
| 271 | if (e->ops->elevator_merge_fn) |
| 272 | return e->ops->elevator_merge_fn(q, req, bio); |
| 273 | |
| 274 | return ELEVATOR_NO_MERGE; |
| 275 | } |
| 276 | |
| 277 | void elv_merged_request(request_queue_t *q, struct request *rq) |
| 278 | { |
| 279 | elevator_t *e = q->elevator; |
| 280 | |
| 281 | if (e->ops->elevator_merged_fn) |
| 282 | e->ops->elevator_merged_fn(q, rq); |
Tejun Heo | 06b8624 | 2005-10-20 16:46:23 +0200 | [diff] [blame] | 283 | |
| 284 | q->last_merge = rq; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 285 | } |
| 286 | |
| 287 | void elv_merge_requests(request_queue_t *q, struct request *rq, |
| 288 | struct request *next) |
| 289 | { |
| 290 | elevator_t *e = q->elevator; |
| 291 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 292 | if (e->ops->elevator_merge_req_fn) |
| 293 | e->ops->elevator_merge_req_fn(q, rq, next); |
Tejun Heo | 15853af | 2005-11-10 08:52:05 +0100 | [diff] [blame] | 294 | q->nr_sorted--; |
Tejun Heo | 06b8624 | 2005-10-20 16:46:23 +0200 | [diff] [blame] | 295 | |
| 296 | q->last_merge = rq; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 297 | } |
| 298 | |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 299 | void elv_requeue_request(request_queue_t *q, struct request *rq) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 300 | { |
| 301 | elevator_t *e = q->elevator; |
| 302 | |
| 303 | /* |
| 304 | * it already went through dequeue, we need to decrement the |
| 305 | * in_flight count again |
| 306 | */ |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 307 | if (blk_account_rq(rq)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 308 | q->in_flight--; |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 309 | if (blk_sorted_rq(rq) && e->ops->elevator_deactivate_req_fn) |
| 310 | e->ops->elevator_deactivate_req_fn(q, rq); |
| 311 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 312 | |
| 313 | rq->flags &= ~REQ_STARTED; |
| 314 | |
Tejun Heo | 30e9656 | 2006-02-08 01:01:31 -0800 | [diff] [blame] | 315 | elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 316 | } |
| 317 | |
Tejun Heo | 15853af | 2005-11-10 08:52:05 +0100 | [diff] [blame] | 318 | static void elv_drain_elevator(request_queue_t *q) |
| 319 | { |
| 320 | static int printed; |
| 321 | while (q->elevator->ops->elevator_dispatch_fn(q, 1)) |
| 322 | ; |
| 323 | if (q->nr_sorted == 0) |
| 324 | return; |
| 325 | if (printed++ < 10) { |
| 326 | printk(KERN_ERR "%s: forced dispatching is broken " |
| 327 | "(nr_sorted=%u), please report this\n", |
| 328 | q->elevator->elevator_type->elevator_name, q->nr_sorted); |
| 329 | } |
| 330 | } |
| 331 | |
Tejun Heo | 30e9656 | 2006-02-08 01:01:31 -0800 | [diff] [blame] | 332 | void elv_insert(request_queue_t *q, struct request *rq, int where) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 333 | { |
Tejun Heo | 797e7db | 2006-01-06 09:51:03 +0100 | [diff] [blame] | 334 | struct list_head *pos; |
| 335 | unsigned ordseq; |
| 336 | |
Jens Axboe | 2056a78 | 2006-03-23 20:00:26 +0100 | [diff] [blame] | 337 | blk_add_trace_rq(q, rq, BLK_TA_INSERT); |
| 338 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 339 | rq->q = q; |
| 340 | |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 341 | switch (where) { |
| 342 | case ELEVATOR_INSERT_FRONT: |
| 343 | rq->flags |= REQ_SOFTBARRIER; |
| 344 | |
| 345 | list_add(&rq->queuelist, &q->queue_head); |
| 346 | break; |
| 347 | |
| 348 | case ELEVATOR_INSERT_BACK: |
| 349 | rq->flags |= REQ_SOFTBARRIER; |
Tejun Heo | 15853af | 2005-11-10 08:52:05 +0100 | [diff] [blame] | 350 | elv_drain_elevator(q); |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 351 | list_add_tail(&rq->queuelist, &q->queue_head); |
| 352 | /* |
| 353 | * We kick the queue here for the following reasons. |
| 354 | * - The elevator might have returned NULL previously |
| 355 | * to delay requests and returned them now. As the |
| 356 | * queue wasn't empty before this request, ll_rw_blk |
| 357 | * won't run the queue on return, resulting in hang. |
| 358 | * - Usually, back inserted requests won't be merged |
| 359 | * with anything. There's no point in delaying queue |
| 360 | * processing. |
| 361 | */ |
| 362 | blk_remove_plug(q); |
| 363 | q->request_fn(q); |
| 364 | break; |
| 365 | |
| 366 | case ELEVATOR_INSERT_SORT: |
| 367 | BUG_ON(!blk_fs_request(rq)); |
| 368 | rq->flags |= REQ_SORTED; |
Tejun Heo | 15853af | 2005-11-10 08:52:05 +0100 | [diff] [blame] | 369 | q->nr_sorted++; |
Tejun Heo | 06b8624 | 2005-10-20 16:46:23 +0200 | [diff] [blame] | 370 | if (q->last_merge == NULL && rq_mergeable(rq)) |
| 371 | q->last_merge = rq; |
Tejun Heo | ca23509 | 2005-11-01 17:23:49 +0900 | [diff] [blame] | 372 | /* |
| 373 | * Some ioscheds (cfq) run q->request_fn directly, so |
| 374 | * rq cannot be accessed after calling |
| 375 | * elevator_add_req_fn. |
| 376 | */ |
| 377 | q->elevator->ops->elevator_add_req_fn(q, rq); |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 378 | break; |
| 379 | |
Tejun Heo | 797e7db | 2006-01-06 09:51:03 +0100 | [diff] [blame] | 380 | case ELEVATOR_INSERT_REQUEUE: |
| 381 | /* |
| 382 | * If ordered flush isn't in progress, we do front |
| 383 | * insertion; otherwise, requests should be requeued |
| 384 | * in ordseq order. |
| 385 | */ |
| 386 | rq->flags |= REQ_SOFTBARRIER; |
| 387 | |
| 388 | if (q->ordseq == 0) { |
| 389 | list_add(&rq->queuelist, &q->queue_head); |
| 390 | break; |
| 391 | } |
| 392 | |
| 393 | ordseq = blk_ordered_req_seq(rq); |
| 394 | |
| 395 | list_for_each(pos, &q->queue_head) { |
| 396 | struct request *pos_rq = list_entry_rq(pos); |
| 397 | if (ordseq <= blk_ordered_req_seq(pos_rq)) |
| 398 | break; |
| 399 | } |
| 400 | |
| 401 | list_add_tail(&rq->queuelist, pos); |
| 402 | break; |
| 403 | |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 404 | default: |
| 405 | printk(KERN_ERR "%s: bad insertion point %d\n", |
| 406 | __FUNCTION__, where); |
| 407 | BUG(); |
| 408 | } |
| 409 | |
| 410 | if (blk_queue_plugged(q)) { |
| 411 | int nrq = q->rq.count[READ] + q->rq.count[WRITE] |
| 412 | - q->in_flight; |
| 413 | |
| 414 | if (nrq >= q->unplug_thresh) |
| 415 | __generic_unplug_device(q); |
| 416 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 417 | } |
| 418 | |
Tejun Heo | 30e9656 | 2006-02-08 01:01:31 -0800 | [diff] [blame] | 419 | void __elv_add_request(request_queue_t *q, struct request *rq, int where, |
| 420 | int plug) |
| 421 | { |
| 422 | if (q->ordcolor) |
| 423 | rq->flags |= REQ_ORDERED_COLOR; |
| 424 | |
| 425 | if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { |
| 426 | /* |
| 427 | * toggle ordered color |
| 428 | */ |
| 429 | if (blk_barrier_rq(rq)) |
| 430 | q->ordcolor ^= 1; |
| 431 | |
| 432 | /* |
| 433 | * barriers implicitly indicate back insertion |
| 434 | */ |
| 435 | if (where == ELEVATOR_INSERT_SORT) |
| 436 | where = ELEVATOR_INSERT_BACK; |
| 437 | |
| 438 | /* |
| 439 | * this request is scheduling boundary, update |
| 440 | * end_sector |
| 441 | */ |
| 442 | if (blk_fs_request(rq)) { |
| 443 | q->end_sector = rq_end_sector(rq); |
| 444 | q->boundary_rq = rq; |
| 445 | } |
| 446 | } else if (!(rq->flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT) |
| 447 | where = ELEVATOR_INSERT_BACK; |
| 448 | |
| 449 | if (plug) |
| 450 | blk_plug_device(q); |
| 451 | |
| 452 | elv_insert(q, rq, where); |
| 453 | } |
| 454 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 455 | void elv_add_request(request_queue_t *q, struct request *rq, int where, |
| 456 | int plug) |
| 457 | { |
| 458 | unsigned long flags; |
| 459 | |
| 460 | spin_lock_irqsave(q->queue_lock, flags); |
| 461 | __elv_add_request(q, rq, where, plug); |
| 462 | spin_unlock_irqrestore(q->queue_lock, flags); |
| 463 | } |
| 464 | |
| 465 | static inline struct request *__elv_next_request(request_queue_t *q) |
| 466 | { |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 467 | struct request *rq; |
| 468 | |
Tejun Heo | 797e7db | 2006-01-06 09:51:03 +0100 | [diff] [blame] | 469 | while (1) { |
| 470 | while (!list_empty(&q->queue_head)) { |
| 471 | rq = list_entry_rq(q->queue_head.next); |
| 472 | if (blk_do_ordered(q, &rq)) |
| 473 | return rq; |
| 474 | } |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 475 | |
Tejun Heo | 797e7db | 2006-01-06 09:51:03 +0100 | [diff] [blame] | 476 | if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) |
| 477 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 478 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 479 | } |
| 480 | |
| 481 | struct request *elv_next_request(request_queue_t *q) |
| 482 | { |
| 483 | struct request *rq; |
| 484 | int ret; |
| 485 | |
| 486 | while ((rq = __elv_next_request(q)) != NULL) { |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 487 | if (!(rq->flags & REQ_STARTED)) { |
| 488 | elevator_t *e = q->elevator; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 489 | |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 490 | /* |
| 491 | * This is the first time the device driver |
| 492 | * sees this request (possibly after |
| 493 | * requeueing). Notify IO scheduler. |
| 494 | */ |
| 495 | if (blk_sorted_rq(rq) && |
| 496 | e->ops->elevator_activate_req_fn) |
| 497 | e->ops->elevator_activate_req_fn(q, rq); |
| 498 | |
| 499 | /* |
| 500 | * just mark as started even if we don't start |
| 501 | * it, a request that has been delayed should |
| 502 | * not be passed by new incoming requests |
| 503 | */ |
| 504 | rq->flags |= REQ_STARTED; |
Jens Axboe | 2056a78 | 2006-03-23 20:00:26 +0100 | [diff] [blame] | 505 | blk_add_trace_rq(q, rq, BLK_TA_ISSUE); |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 506 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 507 | |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 508 | if (!q->boundary_rq || q->boundary_rq == rq) { |
Jens Axboe | 1b47f53 | 2005-10-20 16:37:00 +0200 | [diff] [blame] | 509 | q->end_sector = rq_end_sector(rq); |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 510 | q->boundary_rq = NULL; |
| 511 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 512 | |
| 513 | if ((rq->flags & REQ_DONTPREP) || !q->prep_rq_fn) |
| 514 | break; |
| 515 | |
| 516 | ret = q->prep_rq_fn(q, rq); |
| 517 | if (ret == BLKPREP_OK) { |
| 518 | break; |
| 519 | } else if (ret == BLKPREP_DEFER) { |
Tejun Heo | 2e759cd | 2005-04-24 02:04:21 -0500 | [diff] [blame] | 520 | /* |
| 521 | * the request may have been (partially) prepped. |
| 522 | * we need to keep this request in the front to |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 523 | * avoid resource deadlock. REQ_STARTED will |
| 524 | * prevent other fs requests from passing this one. |
Tejun Heo | 2e759cd | 2005-04-24 02:04:21 -0500 | [diff] [blame] | 525 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 526 | rq = NULL; |
| 527 | break; |
| 528 | } else if (ret == BLKPREP_KILL) { |
| 529 | int nr_bytes = rq->hard_nr_sectors << 9; |
| 530 | |
| 531 | if (!nr_bytes) |
| 532 | nr_bytes = rq->data_len; |
| 533 | |
| 534 | blkdev_dequeue_request(rq); |
| 535 | rq->flags |= REQ_QUIET; |
| 536 | end_that_request_chunk(rq, 0, nr_bytes); |
Tejun Heo | 8ffdc65 | 2006-01-06 09:49:03 +0100 | [diff] [blame] | 537 | end_that_request_last(rq, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 538 | } else { |
| 539 | printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__, |
| 540 | ret); |
| 541 | break; |
| 542 | } |
| 543 | } |
| 544 | |
| 545 | return rq; |
| 546 | } |
| 547 | |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 548 | void elv_dequeue_request(request_queue_t *q, struct request *rq) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 549 | { |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 550 | BUG_ON(list_empty(&rq->queuelist)); |
| 551 | |
| 552 | list_del_init(&rq->queuelist); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 553 | |
| 554 | /* |
| 555 | * the time frame between a request being removed from the lists |
| 556 | * and to it is freed is accounted as io that is in progress at |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 557 | * the driver side. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 558 | */ |
| 559 | if (blk_account_rq(rq)) |
| 560 | q->in_flight++; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 561 | } |
| 562 | |
| 563 | int elv_queue_empty(request_queue_t *q) |
| 564 | { |
| 565 | elevator_t *e = q->elevator; |
| 566 | |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 567 | if (!list_empty(&q->queue_head)) |
| 568 | return 0; |
| 569 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 570 | if (e->ops->elevator_queue_empty_fn) |
| 571 | return e->ops->elevator_queue_empty_fn(q); |
| 572 | |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 573 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 574 | } |
| 575 | |
| 576 | struct request *elv_latter_request(request_queue_t *q, struct request *rq) |
| 577 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 578 | elevator_t *e = q->elevator; |
| 579 | |
| 580 | if (e->ops->elevator_latter_req_fn) |
| 581 | return e->ops->elevator_latter_req_fn(q, rq); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 582 | return NULL; |
| 583 | } |
| 584 | |
| 585 | struct request *elv_former_request(request_queue_t *q, struct request *rq) |
| 586 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 587 | elevator_t *e = q->elevator; |
| 588 | |
| 589 | if (e->ops->elevator_former_req_fn) |
| 590 | return e->ops->elevator_former_req_fn(q, rq); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 591 | return NULL; |
| 592 | } |
| 593 | |
Jens Axboe | 22e2c50 | 2005-06-27 10:55:12 +0200 | [diff] [blame] | 594 | int elv_set_request(request_queue_t *q, struct request *rq, struct bio *bio, |
Al Viro | 8267e26 | 2005-10-21 03:20:53 -0400 | [diff] [blame] | 595 | gfp_t gfp_mask) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 596 | { |
| 597 | elevator_t *e = q->elevator; |
| 598 | |
| 599 | if (e->ops->elevator_set_req_fn) |
Jens Axboe | 22e2c50 | 2005-06-27 10:55:12 +0200 | [diff] [blame] | 600 | return e->ops->elevator_set_req_fn(q, rq, bio, gfp_mask); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 601 | |
| 602 | rq->elevator_private = NULL; |
| 603 | return 0; |
| 604 | } |
| 605 | |
| 606 | void elv_put_request(request_queue_t *q, struct request *rq) |
| 607 | { |
| 608 | elevator_t *e = q->elevator; |
| 609 | |
| 610 | if (e->ops->elevator_put_req_fn) |
| 611 | e->ops->elevator_put_req_fn(q, rq); |
| 612 | } |
| 613 | |
Jens Axboe | 22e2c50 | 2005-06-27 10:55:12 +0200 | [diff] [blame] | 614 | int elv_may_queue(request_queue_t *q, int rw, struct bio *bio) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 615 | { |
| 616 | elevator_t *e = q->elevator; |
| 617 | |
| 618 | if (e->ops->elevator_may_queue_fn) |
Jens Axboe | 22e2c50 | 2005-06-27 10:55:12 +0200 | [diff] [blame] | 619 | return e->ops->elevator_may_queue_fn(q, rw, bio); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 620 | |
| 621 | return ELV_MQUEUE_MAY; |
| 622 | } |
| 623 | |
| 624 | void elv_completed_request(request_queue_t *q, struct request *rq) |
| 625 | { |
| 626 | elevator_t *e = q->elevator; |
| 627 | |
| 628 | /* |
| 629 | * request is released from the driver, io must be done |
| 630 | */ |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 631 | if (blk_account_rq(rq)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 632 | q->in_flight--; |
Tejun Heo | 1bc691d | 2006-01-12 15:39:26 +0100 | [diff] [blame] | 633 | if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn) |
| 634 | e->ops->elevator_completed_req_fn(q, rq); |
| 635 | } |
Tejun Heo | 797e7db | 2006-01-06 09:51:03 +0100 | [diff] [blame] | 636 | |
Tejun Heo | 1bc691d | 2006-01-12 15:39:26 +0100 | [diff] [blame] | 637 | /* |
| 638 | * Check if the queue is waiting for fs requests to be |
| 639 | * drained for flush sequence. |
| 640 | */ |
| 641 | if (unlikely(q->ordseq)) { |
| 642 | struct request *first_rq = list_entry_rq(q->queue_head.next); |
| 643 | if (q->in_flight == 0 && |
Tejun Heo | 797e7db | 2006-01-06 09:51:03 +0100 | [diff] [blame] | 644 | blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN && |
| 645 | blk_ordered_req_seq(first_rq) > QUEUE_ORDSEQ_DRAIN) { |
| 646 | blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0); |
| 647 | q->request_fn(q); |
| 648 | } |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 649 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 650 | } |
| 651 | |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 652 | #define to_elv(atr) container_of((atr), struct elv_fs_entry, attr) |
| 653 | |
| 654 | static ssize_t |
| 655 | elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) |
| 656 | { |
| 657 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
| 658 | struct elv_fs_entry *entry = to_elv(attr); |
| 659 | ssize_t error; |
| 660 | |
| 661 | if (!entry->show) |
| 662 | return -EIO; |
| 663 | |
| 664 | mutex_lock(&e->sysfs_lock); |
| 665 | error = e->ops ? entry->show(e, page) : -ENOENT; |
| 666 | mutex_unlock(&e->sysfs_lock); |
| 667 | return error; |
| 668 | } |
| 669 | |
| 670 | static ssize_t |
| 671 | elv_attr_store(struct kobject *kobj, struct attribute *attr, |
| 672 | const char *page, size_t length) |
| 673 | { |
| 674 | elevator_t *e = container_of(kobj, elevator_t, kobj); |
| 675 | struct elv_fs_entry *entry = to_elv(attr); |
| 676 | ssize_t error; |
| 677 | |
| 678 | if (!entry->store) |
| 679 | return -EIO; |
| 680 | |
| 681 | mutex_lock(&e->sysfs_lock); |
| 682 | error = e->ops ? entry->store(e, page, length) : -ENOENT; |
| 683 | mutex_unlock(&e->sysfs_lock); |
| 684 | return error; |
| 685 | } |
| 686 | |
| 687 | static struct sysfs_ops elv_sysfs_ops = { |
| 688 | .show = elv_attr_show, |
| 689 | .store = elv_attr_store, |
| 690 | }; |
| 691 | |
| 692 | static struct kobj_type elv_ktype = { |
| 693 | .sysfs_ops = &elv_sysfs_ops, |
| 694 | .release = elevator_release, |
| 695 | }; |
| 696 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 697 | int elv_register_queue(struct request_queue *q) |
| 698 | { |
| 699 | elevator_t *e = q->elevator; |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 700 | int error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 701 | |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 702 | e->kobj.parent = &q->kobj; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 703 | |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 704 | error = kobject_add(&e->kobj); |
| 705 | if (!error) { |
Al Viro | e572ec7 | 2006-03-18 22:27:18 -0500 | [diff] [blame] | 706 | struct elv_fs_entry *attr = e->elevator_type->elevator_attrs; |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 707 | if (attr) { |
Al Viro | e572ec7 | 2006-03-18 22:27:18 -0500 | [diff] [blame] | 708 | while (attr->attr.name) { |
| 709 | if (sysfs_create_file(&e->kobj, &attr->attr)) |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 710 | break; |
Al Viro | e572ec7 | 2006-03-18 22:27:18 -0500 | [diff] [blame] | 711 | attr++; |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 712 | } |
| 713 | } |
| 714 | kobject_uevent(&e->kobj, KOBJ_ADD); |
| 715 | } |
| 716 | return error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 717 | } |
| 718 | |
| 719 | void elv_unregister_queue(struct request_queue *q) |
| 720 | { |
| 721 | if (q) { |
| 722 | elevator_t *e = q->elevator; |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 723 | kobject_uevent(&e->kobj, KOBJ_REMOVE); |
| 724 | kobject_del(&e->kobj); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 725 | } |
| 726 | } |
| 727 | |
| 728 | int elv_register(struct elevator_type *e) |
| 729 | { |
Tejun Heo | 2824bc93 | 2005-10-20 10:56:41 +0200 | [diff] [blame] | 730 | spin_lock_irq(&elv_list_lock); |
Eric Sesterhenn | ce52449 | 2006-03-24 18:43:26 +0100 | [diff] [blame] | 731 | BUG_ON(elevator_find(e->elevator_name)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 732 | list_add_tail(&e->list, &elv_list); |
| 733 | spin_unlock_irq(&elv_list_lock); |
| 734 | |
| 735 | printk(KERN_INFO "io scheduler %s registered", e->elevator_name); |
Nate Diller | 5f00397 | 2006-01-24 10:07:58 +0100 | [diff] [blame] | 736 | if (!strcmp(e->elevator_name, chosen_elevator) || |
| 737 | (!*chosen_elevator && |
| 738 | !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) |
| 739 | printk(" (default)"); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 740 | printk("\n"); |
| 741 | return 0; |
| 742 | } |
| 743 | EXPORT_SYMBOL_GPL(elv_register); |
| 744 | |
| 745 | void elv_unregister(struct elevator_type *e) |
| 746 | { |
Christoph Hellwig | 83521d3 | 2005-10-30 15:01:39 -0800 | [diff] [blame] | 747 | struct task_struct *g, *p; |
| 748 | |
| 749 | /* |
| 750 | * Iterate every thread in the process to remove the io contexts. |
| 751 | */ |
Al Viro | e17a948 | 2006-03-18 13:21:20 -0500 | [diff] [blame] | 752 | if (e->ops.trim) { |
| 753 | read_lock(&tasklist_lock); |
| 754 | do_each_thread(g, p) { |
| 755 | task_lock(p); |
| 756 | e->ops.trim(p->io_context); |
| 757 | task_unlock(p); |
| 758 | } while_each_thread(g, p); |
| 759 | read_unlock(&tasklist_lock); |
| 760 | } |
Christoph Hellwig | 83521d3 | 2005-10-30 15:01:39 -0800 | [diff] [blame] | 761 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 762 | spin_lock_irq(&elv_list_lock); |
| 763 | list_del_init(&e->list); |
| 764 | spin_unlock_irq(&elv_list_lock); |
| 765 | } |
| 766 | EXPORT_SYMBOL_GPL(elv_unregister); |
| 767 | |
| 768 | /* |
| 769 | * switch to new_e io scheduler. be careful not to introduce deadlocks - |
| 770 | * we don't free the old io scheduler, before we have allocated what we |
| 771 | * need for the new one. this way we have a chance of going back to the old |
Tejun Heo | cb98fc8 | 2005-10-28 08:29:39 +0200 | [diff] [blame] | 772 | * one, if the new one fails init for some reason. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 773 | */ |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 774 | static int elevator_switch(request_queue_t *q, struct elevator_type *new_e) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 775 | { |
Tejun Heo | cb98fc8 | 2005-10-28 08:29:39 +0200 | [diff] [blame] | 776 | elevator_t *old_elevator, *e; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 777 | |
Tejun Heo | cb98fc8 | 2005-10-28 08:29:39 +0200 | [diff] [blame] | 778 | /* |
| 779 | * Allocate new elevator |
| 780 | */ |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 781 | e = elevator_alloc(new_e); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 782 | if (!e) |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 783 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 784 | |
| 785 | /* |
Tejun Heo | cb98fc8 | 2005-10-28 08:29:39 +0200 | [diff] [blame] | 786 | * Turn on BYPASS and drain all requests w/ elevator private data |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 787 | */ |
Tejun Heo | cb98fc8 | 2005-10-28 08:29:39 +0200 | [diff] [blame] | 788 | spin_lock_irq(q->queue_lock); |
| 789 | |
Jens Axboe | 64521d1 | 2005-10-28 08:30:39 +0200 | [diff] [blame] | 790 | set_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
Tejun Heo | cb98fc8 | 2005-10-28 08:29:39 +0200 | [diff] [blame] | 791 | |
Tejun Heo | 15853af | 2005-11-10 08:52:05 +0100 | [diff] [blame] | 792 | elv_drain_elevator(q); |
Tejun Heo | cb98fc8 | 2005-10-28 08:29:39 +0200 | [diff] [blame] | 793 | |
| 794 | while (q->rq.elvpriv) { |
Tejun Heo | 407df2a | 2005-11-10 08:48:21 +0100 | [diff] [blame] | 795 | blk_remove_plug(q); |
| 796 | q->request_fn(q); |
Tejun Heo | cb98fc8 | 2005-10-28 08:29:39 +0200 | [diff] [blame] | 797 | spin_unlock_irq(q->queue_lock); |
Jens Axboe | 64521d1 | 2005-10-28 08:30:39 +0200 | [diff] [blame] | 798 | msleep(10); |
Tejun Heo | cb98fc8 | 2005-10-28 08:29:39 +0200 | [diff] [blame] | 799 | spin_lock_irq(q->queue_lock); |
Tejun Heo | 15853af | 2005-11-10 08:52:05 +0100 | [diff] [blame] | 800 | elv_drain_elevator(q); |
Tejun Heo | cb98fc8 | 2005-10-28 08:29:39 +0200 | [diff] [blame] | 801 | } |
| 802 | |
| 803 | spin_unlock_irq(q->queue_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 804 | |
| 805 | /* |
| 806 | * unregister old elevator data |
| 807 | */ |
| 808 | elv_unregister_queue(q); |
| 809 | old_elevator = q->elevator; |
| 810 | |
| 811 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 812 | * attach and start new elevator |
| 813 | */ |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 814 | if (elevator_attach(q, e)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 815 | goto fail; |
| 816 | |
| 817 | if (elv_register_queue(q)) |
| 818 | goto fail_register; |
| 819 | |
| 820 | /* |
Tejun Heo | cb98fc8 | 2005-10-28 08:29:39 +0200 | [diff] [blame] | 821 | * finally exit old elevator and turn off BYPASS. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 822 | */ |
| 823 | elevator_exit(old_elevator); |
Jens Axboe | 64521d1 | 2005-10-28 08:30:39 +0200 | [diff] [blame] | 824 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 825 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 826 | |
| 827 | fail_register: |
| 828 | /* |
| 829 | * switch failed, exit the new io scheduler and reattach the old |
| 830 | * one again (along with re-adding the sysfs dir) |
| 831 | */ |
| 832 | elevator_exit(e); |
Tejun Heo | cb98fc8 | 2005-10-28 08:29:39 +0200 | [diff] [blame] | 833 | e = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 834 | fail: |
| 835 | q->elevator = old_elevator; |
| 836 | elv_register_queue(q); |
Jens Axboe | 64521d1 | 2005-10-28 08:30:39 +0200 | [diff] [blame] | 837 | clear_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 838 | if (e) |
| 839 | kobject_put(&e->kobj); |
| 840 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 841 | } |
| 842 | |
| 843 | ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count) |
| 844 | { |
| 845 | char elevator_name[ELV_NAME_MAX]; |
Tejun Heo | be56123 | 2005-11-10 08:55:01 +0100 | [diff] [blame] | 846 | size_t len; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 847 | struct elevator_type *e; |
| 848 | |
Tejun Heo | be56123 | 2005-11-10 08:55:01 +0100 | [diff] [blame] | 849 | elevator_name[sizeof(elevator_name) - 1] = '\0'; |
| 850 | strncpy(elevator_name, name, sizeof(elevator_name) - 1); |
| 851 | len = strlen(elevator_name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 852 | |
Tejun Heo | be56123 | 2005-11-10 08:55:01 +0100 | [diff] [blame] | 853 | if (len && elevator_name[len - 1] == '\n') |
| 854 | elevator_name[len - 1] = '\0'; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 855 | |
| 856 | e = elevator_get(elevator_name); |
| 857 | if (!e) { |
| 858 | printk(KERN_ERR "elevator: type %s not found\n", elevator_name); |
| 859 | return -EINVAL; |
| 860 | } |
| 861 | |
Nate Diller | 2ca7d93 | 2005-10-30 15:02:24 -0800 | [diff] [blame] | 862 | if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
| 863 | elevator_put(e); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 864 | return count; |
Nate Diller | 2ca7d93 | 2005-10-30 15:02:24 -0800 | [diff] [blame] | 865 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 866 | |
Al Viro | 3d1ab40 | 2006-03-18 18:35:43 -0500 | [diff] [blame] | 867 | if (!elevator_switch(q, e)) |
| 868 | printk(KERN_ERR "elevator: switch to %s failed\n",elevator_name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 869 | return count; |
| 870 | } |
| 871 | |
| 872 | ssize_t elv_iosched_show(request_queue_t *q, char *name) |
| 873 | { |
| 874 | elevator_t *e = q->elevator; |
| 875 | struct elevator_type *elv = e->elevator_type; |
| 876 | struct list_head *entry; |
| 877 | int len = 0; |
| 878 | |
| 879 | spin_lock_irq(q->queue_lock); |
| 880 | list_for_each(entry, &elv_list) { |
| 881 | struct elevator_type *__e; |
| 882 | |
| 883 | __e = list_entry(entry, struct elevator_type, list); |
| 884 | if (!strcmp(elv->elevator_name, __e->elevator_name)) |
| 885 | len += sprintf(name+len, "[%s] ", elv->elevator_name); |
| 886 | else |
| 887 | len += sprintf(name+len, "%s ", __e->elevator_name); |
| 888 | } |
| 889 | spin_unlock_irq(q->queue_lock); |
| 890 | |
| 891 | len += sprintf(len+name, "\n"); |
| 892 | return len; |
| 893 | } |
| 894 | |
Jens Axboe | 1b47f53 | 2005-10-20 16:37:00 +0200 | [diff] [blame] | 895 | EXPORT_SYMBOL(elv_dispatch_sort); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 896 | EXPORT_SYMBOL(elv_add_request); |
| 897 | EXPORT_SYMBOL(__elv_add_request); |
| 898 | EXPORT_SYMBOL(elv_requeue_request); |
| 899 | EXPORT_SYMBOL(elv_next_request); |
Tejun Heo | 8922e16 | 2005-10-20 16:23:44 +0200 | [diff] [blame] | 900 | EXPORT_SYMBOL(elv_dequeue_request); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 901 | EXPORT_SYMBOL(elv_queue_empty); |
| 902 | EXPORT_SYMBOL(elv_completed_request); |
| 903 | EXPORT_SYMBOL(elevator_exit); |
| 904 | EXPORT_SYMBOL(elevator_init); |