blob: 59ee1b015d2df5870f7ac775a6d612adb5f44e11 [file] [log] [blame]
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -07001/*
2 * Copyright (C) 2005-2007 Red Hat GmbH
3 *
4 * A target that delays reads and/or writes and can send
5 * them to different devices.
6 *
7 * This file is released under the GPL.
8 */
9
10#include <linux/module.h>
11#include <linux/init.h>
12#include <linux/blkdev.h>
13#include <linux/bio.h>
14#include <linux/slab.h>
15
Mikulas Patocka586e80e2008-10-21 17:44:59 +010016#include <linux/device-mapper.h>
17
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -070018#include "dm-bio-list.h"
19
20#define DM_MSG_PREFIX "delay"
21
22struct delay_c {
23 struct timer_list delay_timer;
Alasdair G Kergonac818642007-07-12 17:26:47 +010024 struct mutex timer_lock;
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -070025 struct work_struct flush_expired_bios;
26 struct list_head delayed_bios;
27 atomic_t may_delay;
28 mempool_t *delayed_pool;
29
30 struct dm_dev *dev_read;
31 sector_t start_read;
32 unsigned read_delay;
33 unsigned reads;
34
35 struct dm_dev *dev_write;
36 sector_t start_write;
37 unsigned write_delay;
38 unsigned writes;
39};
40
Alasdair G Kergon028867a2007-07-12 17:26:32 +010041struct dm_delay_info {
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -070042 struct delay_c *context;
43 struct list_head list;
44 struct bio *bio;
45 unsigned long expires;
46};
47
48static DEFINE_MUTEX(delayed_bios_lock);
49
50static struct workqueue_struct *kdelayd_wq;
51static struct kmem_cache *delayed_cache;
52
53static void handle_delayed_timer(unsigned long data)
54{
55 struct delay_c *dc = (struct delay_c *)data;
56
57 queue_work(kdelayd_wq, &dc->flush_expired_bios);
58}
59
60static void queue_timeout(struct delay_c *dc, unsigned long expires)
61{
Alasdair G Kergonac818642007-07-12 17:26:47 +010062 mutex_lock(&dc->timer_lock);
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -070063
64 if (!timer_pending(&dc->delay_timer) || expires < dc->delay_timer.expires)
65 mod_timer(&dc->delay_timer, expires);
66
Alasdair G Kergonac818642007-07-12 17:26:47 +010067 mutex_unlock(&dc->timer_lock);
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -070068}
69
70static void flush_bios(struct bio *bio)
71{
72 struct bio *n;
73
74 while (bio) {
75 n = bio->bi_next;
76 bio->bi_next = NULL;
77 generic_make_request(bio);
78 bio = n;
79 }
80}
81
82static struct bio *flush_delayed_bios(struct delay_c *dc, int flush_all)
83{
Alasdair G Kergon028867a2007-07-12 17:26:32 +010084 struct dm_delay_info *delayed, *next;
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -070085 unsigned long next_expires = 0;
86 int start_timer = 0;
Alasdair G Kergon051814c2007-10-19 22:38:55 +010087 struct bio_list flush_bios = { };
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -070088
89 mutex_lock(&delayed_bios_lock);
90 list_for_each_entry_safe(delayed, next, &dc->delayed_bios, list) {
91 if (flush_all || time_after_eq(jiffies, delayed->expires)) {
92 list_del(&delayed->list);
93 bio_list_add(&flush_bios, delayed->bio);
94 if ((bio_data_dir(delayed->bio) == WRITE))
95 delayed->context->writes--;
96 else
97 delayed->context->reads--;
98 mempool_free(delayed, dc->delayed_pool);
99 continue;
100 }
101
102 if (!start_timer) {
103 start_timer = 1;
104 next_expires = delayed->expires;
105 } else
106 next_expires = min(next_expires, delayed->expires);
107 }
108
109 mutex_unlock(&delayed_bios_lock);
110
111 if (start_timer)
112 queue_timeout(dc, next_expires);
113
114 return bio_list_get(&flush_bios);
115}
116
117static void flush_expired_bios(struct work_struct *work)
118{
119 struct delay_c *dc;
120
121 dc = container_of(work, struct delay_c, flush_expired_bios);
122 flush_bios(flush_delayed_bios(dc, 0));
123}
124
125/*
126 * Mapping parameters:
127 * <device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
128 *
129 * With separate write parameters, the first set is only used for reads.
130 * Delays are specified in milliseconds.
131 */
132static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv)
133{
134 struct delay_c *dc;
135 unsigned long long tmpll;
136
137 if (argc != 3 && argc != 6) {
138 ti->error = "requires exactly 3 or 6 arguments";
139 return -EINVAL;
140 }
141
142 dc = kmalloc(sizeof(*dc), GFP_KERNEL);
143 if (!dc) {
144 ti->error = "Cannot allocate context";
145 return -ENOMEM;
146 }
147
148 dc->reads = dc->writes = 0;
149
150 if (sscanf(argv[1], "%llu", &tmpll) != 1) {
151 ti->error = "Invalid device sector";
152 goto bad;
153 }
154 dc->start_read = tmpll;
155
156 if (sscanf(argv[2], "%u", &dc->read_delay) != 1) {
157 ti->error = "Invalid delay";
158 goto bad;
159 }
160
161 if (dm_get_device(ti, argv[0], dc->start_read, ti->len,
162 dm_table_get_mode(ti->table), &dc->dev_read)) {
163 ti->error = "Device lookup failed";
164 goto bad;
165 }
166
Dmitry Monakhov2e64a0f2007-10-19 22:38:41 +0100167 dc->dev_write = NULL;
168 if (argc == 3)
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -0700169 goto out;
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -0700170
171 if (sscanf(argv[4], "%llu", &tmpll) != 1) {
172 ti->error = "Invalid write device sector";
Dmitry Monakhov2e64a0f2007-10-19 22:38:41 +0100173 goto bad_dev_read;
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -0700174 }
175 dc->start_write = tmpll;
176
177 if (sscanf(argv[5], "%u", &dc->write_delay) != 1) {
178 ti->error = "Invalid write delay";
Dmitry Monakhov2e64a0f2007-10-19 22:38:41 +0100179 goto bad_dev_read;
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -0700180 }
181
182 if (dm_get_device(ti, argv[3], dc->start_write, ti->len,
183 dm_table_get_mode(ti->table), &dc->dev_write)) {
184 ti->error = "Write device lookup failed";
Dmitry Monakhov2e64a0f2007-10-19 22:38:41 +0100185 goto bad_dev_read;
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -0700186 }
187
188out:
189 dc->delayed_pool = mempool_create_slab_pool(128, delayed_cache);
190 if (!dc->delayed_pool) {
191 DMERR("Couldn't create delayed bio pool.");
Dmitry Monakhov2e64a0f2007-10-19 22:38:41 +0100192 goto bad_dev_write;
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -0700193 }
194
Alasdair G Kergonac818642007-07-12 17:26:47 +0100195 setup_timer(&dc->delay_timer, handle_delayed_timer, (unsigned long)dc);
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -0700196
197 INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
198 INIT_LIST_HEAD(&dc->delayed_bios);
Alasdair G Kergonac818642007-07-12 17:26:47 +0100199 mutex_init(&dc->timer_lock);
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -0700200 atomic_set(&dc->may_delay, 1);
201
202 ti->private = dc;
203 return 0;
204
Dmitry Monakhov2e64a0f2007-10-19 22:38:41 +0100205bad_dev_write:
206 if (dc->dev_write)
207 dm_put_device(ti, dc->dev_write);
208bad_dev_read:
209 dm_put_device(ti, dc->dev_read);
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -0700210bad:
211 kfree(dc);
212 return -EINVAL;
213}
214
215static void delay_dtr(struct dm_target *ti)
216{
217 struct delay_c *dc = ti->private;
218
219 flush_workqueue(kdelayd_wq);
220
221 dm_put_device(ti, dc->dev_read);
222
223 if (dc->dev_write)
224 dm_put_device(ti, dc->dev_write);
225
226 mempool_destroy(dc->delayed_pool);
227 kfree(dc);
228}
229
230static int delay_bio(struct delay_c *dc, int delay, struct bio *bio)
231{
Alasdair G Kergon028867a2007-07-12 17:26:32 +0100232 struct dm_delay_info *delayed;
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -0700233 unsigned long expires = 0;
234
235 if (!delay || !atomic_read(&dc->may_delay))
236 return 1;
237
238 delayed = mempool_alloc(dc->delayed_pool, GFP_NOIO);
239
240 delayed->context = dc;
241 delayed->bio = bio;
242 delayed->expires = expires = jiffies + (delay * HZ / 1000);
243
244 mutex_lock(&delayed_bios_lock);
245
246 if (bio_data_dir(bio) == WRITE)
247 dc->writes++;
248 else
249 dc->reads++;
250
251 list_add_tail(&delayed->list, &dc->delayed_bios);
252
253 mutex_unlock(&delayed_bios_lock);
254
255 queue_timeout(dc, expires);
256
257 return 0;
258}
259
260static void delay_presuspend(struct dm_target *ti)
261{
262 struct delay_c *dc = ti->private;
263
264 atomic_set(&dc->may_delay, 0);
265 del_timer_sync(&dc->delay_timer);
266 flush_bios(flush_delayed_bios(dc, 1));
267}
268
269static void delay_resume(struct dm_target *ti)
270{
271 struct delay_c *dc = ti->private;
272
273 atomic_set(&dc->may_delay, 1);
274}
275
276static int delay_map(struct dm_target *ti, struct bio *bio,
277 union map_info *map_context)
278{
279 struct delay_c *dc = ti->private;
280
281 if ((bio_data_dir(bio) == WRITE) && (dc->dev_write)) {
282 bio->bi_bdev = dc->dev_write->bdev;
283 bio->bi_sector = dc->start_write +
284 (bio->bi_sector - ti->begin);
285
286 return delay_bio(dc, dc->write_delay, bio);
287 }
288
289 bio->bi_bdev = dc->dev_read->bdev;
290 bio->bi_sector = dc->start_read +
291 (bio->bi_sector - ti->begin);
292
293 return delay_bio(dc, dc->read_delay, bio);
294}
295
296static int delay_status(struct dm_target *ti, status_type_t type,
297 char *result, unsigned maxlen)
298{
299 struct delay_c *dc = ti->private;
300 int sz = 0;
301
302 switch (type) {
303 case STATUSTYPE_INFO:
304 DMEMIT("%u %u", dc->reads, dc->writes);
305 break;
306
307 case STATUSTYPE_TABLE:
308 DMEMIT("%s %llu %u", dc->dev_read->name,
309 (unsigned long long) dc->start_read,
310 dc->read_delay);
311 if (dc->dev_write)
Milan Broz79662d12007-10-19 22:38:42 +0100312 DMEMIT(" %s %llu %u", dc->dev_write->name,
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -0700313 (unsigned long long) dc->start_write,
314 dc->write_delay);
315 break;
316 }
317
318 return 0;
319}
320
321static struct target_type delay_target = {
322 .name = "delay",
323 .version = {1, 0, 2},
324 .module = THIS_MODULE,
325 .ctr = delay_ctr,
326 .dtr = delay_dtr,
327 .map = delay_map,
328 .presuspend = delay_presuspend,
329 .resume = delay_resume,
330 .status = delay_status,
331};
332
333static int __init dm_delay_init(void)
334{
335 int r = -ENOMEM;
336
337 kdelayd_wq = create_workqueue("kdelayd");
338 if (!kdelayd_wq) {
339 DMERR("Couldn't start kdelayd");
340 goto bad_queue;
341 }
342
Alasdair G Kergon028867a2007-07-12 17:26:32 +0100343 delayed_cache = KMEM_CACHE(dm_delay_info, 0);
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -0700344 if (!delayed_cache) {
345 DMERR("Couldn't create delayed bio cache.");
346 goto bad_memcache;
347 }
348
349 r = dm_register_target(&delay_target);
350 if (r < 0) {
351 DMERR("register failed %d", r);
352 goto bad_register;
353 }
354
355 return 0;
356
357bad_register:
358 kmem_cache_destroy(delayed_cache);
359bad_memcache:
360 destroy_workqueue(kdelayd_wq);
361bad_queue:
362 return r;
363}
364
365static void __exit dm_delay_exit(void)
366{
Mikulas Patocka10d3bd02009-01-06 03:04:58 +0000367 dm_unregister_target(&delay_target);
Heinz Mauelshagen26b9f222007-05-09 02:33:06 -0700368 kmem_cache_destroy(delayed_cache);
369 destroy_workqueue(kdelayd_wq);
370}
371
372/* Module hooks */
373module_init(dm_delay_init);
374module_exit(dm_delay_exit);
375
376MODULE_DESCRIPTION(DM_NAME " delay target");
377MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
378MODULE_LICENSE("GPL");