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authorHeinz Mauelshagen <mauelshagen@redhat.com>2007-05-09 05:33:06 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-09 15:30:47 -0400
commit26b9f228703f0518a90e7513d6fe7b6abeed5138 (patch)
tree3437e92667c338ea46ad47b064ce4908d7d75fe2 /drivers/md/dm-delay.c
parent0ba699347e96b5468b42b3decf1f381abbf99652 (diff)
dm: delay target
New device-mapper target that can delay I/O (for testing). Reads can be separated from writes, redirected to different underlying devices and delayed by differing amounts of time. Signed-off-by: Heinz Mauelshagen <mauelshagen@redhat.com> Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/md/dm-delay.c')
-rw-r--r--drivers/md/dm-delay.c383
1 files changed, 383 insertions, 0 deletions
diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c
new file mode 100644
index 000000000000..52c7cf9e5803
--- /dev/null
+++ b/drivers/md/dm-delay.c
@@ -0,0 +1,383 @@
1/*
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
16#include "dm.h"
17#include "dm-bio-list.h"
18
19#define DM_MSG_PREFIX "delay"
20
21struct delay_c {
22 struct timer_list delay_timer;
23 struct semaphore timer_lock;
24 struct work_struct flush_expired_bios;
25 struct list_head delayed_bios;
26 atomic_t may_delay;
27 mempool_t *delayed_pool;
28
29 struct dm_dev *dev_read;
30 sector_t start_read;
31 unsigned read_delay;
32 unsigned reads;
33
34 struct dm_dev *dev_write;
35 sector_t start_write;
36 unsigned write_delay;
37 unsigned writes;
38};
39
40struct delay_info {
41 struct delay_c *context;
42 struct list_head list;
43 struct bio *bio;
44 unsigned long expires;
45};
46
47static DEFINE_MUTEX(delayed_bios_lock);
48
49static struct workqueue_struct *kdelayd_wq;
50static struct kmem_cache *delayed_cache;
51
52static void handle_delayed_timer(unsigned long data)
53{
54 struct delay_c *dc = (struct delay_c *)data;
55
56 queue_work(kdelayd_wq, &dc->flush_expired_bios);
57}
58
59static void queue_timeout(struct delay_c *dc, unsigned long expires)
60{
61 down(&dc->timer_lock);
62
63 if (!timer_pending(&dc->delay_timer) || expires < dc->delay_timer.expires)
64 mod_timer(&dc->delay_timer, expires);
65
66 up(&dc->timer_lock);
67}
68
69static void flush_bios(struct bio *bio)
70{
71 struct bio *n;
72
73 while (bio) {
74 n = bio->bi_next;
75 bio->bi_next = NULL;
76 generic_make_request(bio);
77 bio = n;
78 }
79}
80
81static struct bio *flush_delayed_bios(struct delay_c *dc, int flush_all)
82{
83 struct delay_info *delayed, *next;
84 unsigned long next_expires = 0;
85 int start_timer = 0;
86 BIO_LIST(flush_bios);
87
88 mutex_lock(&delayed_bios_lock);
89 list_for_each_entry_safe(delayed, next, &dc->delayed_bios, list) {
90 if (flush_all || time_after_eq(jiffies, delayed->expires)) {
91 list_del(&delayed->list);
92 bio_list_add(&flush_bios, delayed->bio);
93 if ((bio_data_dir(delayed->bio) == WRITE))
94 delayed->context->writes--;
95 else
96 delayed->context->reads--;
97 mempool_free(delayed, dc->delayed_pool);
98 continue;
99 }
100
101 if (!start_timer) {
102 start_timer = 1;
103 next_expires = delayed->expires;
104 } else
105 next_expires = min(next_expires, delayed->expires);
106 }
107
108 mutex_unlock(&delayed_bios_lock);
109
110 if (start_timer)
111 queue_timeout(dc, next_expires);
112
113 return bio_list_get(&flush_bios);
114}
115
116static void flush_expired_bios(struct work_struct *work)
117{
118 struct delay_c *dc;
119
120 dc = container_of(work, struct delay_c, flush_expired_bios);
121 flush_bios(flush_delayed_bios(dc, 0));
122}
123
124/*
125 * Mapping parameters:
126 * <device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
127 *
128 * With separate write parameters, the first set is only used for reads.
129 * Delays are specified in milliseconds.
130 */
131static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv)
132{
133 struct delay_c *dc;
134 unsigned long long tmpll;
135
136 if (argc != 3 && argc != 6) {
137 ti->error = "requires exactly 3 or 6 arguments";
138 return -EINVAL;
139 }
140
141 dc = kmalloc(sizeof(*dc), GFP_KERNEL);
142 if (!dc) {
143 ti->error = "Cannot allocate context";
144 return -ENOMEM;
145 }
146
147 dc->reads = dc->writes = 0;
148
149 if (sscanf(argv[1], "%llu", &tmpll) != 1) {
150 ti->error = "Invalid device sector";
151 goto bad;
152 }
153 dc->start_read = tmpll;
154
155 if (sscanf(argv[2], "%u", &dc->read_delay) != 1) {
156 ti->error = "Invalid delay";
157 goto bad;
158 }
159
160 if (dm_get_device(ti, argv[0], dc->start_read, ti->len,
161 dm_table_get_mode(ti->table), &dc->dev_read)) {
162 ti->error = "Device lookup failed";
163 goto bad;
164 }
165
166 if (argc == 3) {
167 dc->dev_write = NULL;
168 goto out;
169 }
170
171 if (sscanf(argv[4], "%llu", &tmpll) != 1) {
172 ti->error = "Invalid write device sector";
173 goto bad;
174 }
175 dc->start_write = tmpll;
176
177 if (sscanf(argv[5], "%u", &dc->write_delay) != 1) {
178 ti->error = "Invalid write delay";
179 goto bad;
180 }
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";
185 dm_put_device(ti, dc->dev_read);
186 goto bad;
187 }
188
189out:
190 dc->delayed_pool = mempool_create_slab_pool(128, delayed_cache);
191 if (!dc->delayed_pool) {
192 DMERR("Couldn't create delayed bio pool.");
193 goto bad;
194 }
195
196 init_timer(&dc->delay_timer);
197 dc->delay_timer.function = handle_delayed_timer;
198 dc->delay_timer.data = (unsigned long)dc;
199
200 INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
201 INIT_LIST_HEAD(&dc->delayed_bios);
202 init_MUTEX(&dc->timer_lock);
203 atomic_set(&dc->may_delay, 1);
204
205 ti->private = dc;
206 return 0;
207
208bad:
209 kfree(dc);
210 return -EINVAL;
211}
212
213static void delay_dtr(struct dm_target *ti)
214{
215 struct delay_c *dc = ti->private;
216
217 flush_workqueue(kdelayd_wq);
218
219 dm_put_device(ti, dc->dev_read);
220
221 if (dc->dev_write)
222 dm_put_device(ti, dc->dev_write);
223
224 mempool_destroy(dc->delayed_pool);
225 kfree(dc);
226}
227
228static int delay_bio(struct delay_c *dc, int delay, struct bio *bio)
229{
230 struct delay_info *delayed;
231 unsigned long expires = 0;
232
233 if (!delay || !atomic_read(&dc->may_delay))
234 return 1;
235
236 delayed = mempool_alloc(dc->delayed_pool, GFP_NOIO);
237
238 delayed->context = dc;
239 delayed->bio = bio;
240 delayed->expires = expires = jiffies + (delay * HZ / 1000);
241
242 mutex_lock(&delayed_bios_lock);
243
244 if (bio_data_dir(bio) == WRITE)
245 dc->writes++;
246 else
247 dc->reads++;
248
249 list_add_tail(&delayed->list, &dc->delayed_bios);
250
251 mutex_unlock(&delayed_bios_lock);
252
253 queue_timeout(dc, expires);
254
255 return 0;
256}
257
258static void delay_presuspend(struct dm_target *ti)
259{
260 struct delay_c *dc = ti->private;
261
262 atomic_set(&dc->may_delay, 0);
263 del_timer_sync(&dc->delay_timer);
264 flush_bios(flush_delayed_bios(dc, 1));
265}
266
267static void delay_resume(struct dm_target *ti)
268{
269 struct delay_c *dc = ti->private;
270
271 atomic_set(&dc->may_delay, 1);
272}
273
274static int delay_map(struct dm_target *ti, struct bio *bio,
275 union map_info *map_context)
276{
277 struct delay_c *dc = ti->private;
278
279 if ((bio_data_dir(bio) == WRITE) && (dc->dev_write)) {
280 bio->bi_bdev = dc->dev_write->bdev;
281 bio->bi_sector = dc->start_write +
282 (bio->bi_sector - ti->begin);
283
284 return delay_bio(dc, dc->write_delay, bio);
285 }
286
287 bio->bi_bdev = dc->dev_read->bdev;
288 bio->bi_sector = dc->start_read +
289 (bio->bi_sector - ti->begin);
290
291 return delay_bio(dc, dc->read_delay, bio);
292}
293
294static int delay_status(struct dm_target *ti, status_type_t type,
295 char *result, unsigned maxlen)
296{
297 struct delay_c *dc = ti->private;
298 int sz = 0;
299
300 switch (type) {
301 case STATUSTYPE_INFO:
302 DMEMIT("%u %u", dc->reads, dc->writes);
303 break;
304
305 case STATUSTYPE_TABLE:
306 DMEMIT("%s %llu %u", dc->dev_read->name,
307 (unsigned long long) dc->start_read,
308 dc->read_delay);
309 if (dc->dev_write)
310 DMEMIT("%s %llu %u", dc->dev_write->name,
311 (unsigned long long) dc->start_write,
312 dc->write_delay);
313 break;
314 }
315
316 return 0;
317}
318
319static struct target_type delay_target = {
320 .name = "delay",
321 .version = {1, 0, 2},
322 .module = THIS_MODULE,
323 .ctr = delay_ctr,
324 .dtr = delay_dtr,
325 .map = delay_map,
326 .presuspend = delay_presuspend,
327 .resume = delay_resume,
328 .status = delay_status,
329};
330
331static int __init dm_delay_init(void)
332{
333 int r = -ENOMEM;
334
335 kdelayd_wq = create_workqueue("kdelayd");
336 if (!kdelayd_wq) {
337 DMERR("Couldn't start kdelayd");
338 goto bad_queue;
339 }
340
341 delayed_cache = kmem_cache_create("dm-delay",
342 sizeof(struct delay_info),
343 __alignof__(struct delay_info),
344 0, NULL, NULL);
345 if (!delayed_cache) {
346 DMERR("Couldn't create delayed bio cache.");
347 goto bad_memcache;
348 }
349
350 r = dm_register_target(&delay_target);
351 if (r < 0) {
352 DMERR("register failed %d", r);
353 goto bad_register;
354 }
355
356 return 0;
357
358bad_register:
359 kmem_cache_destroy(delayed_cache);
360bad_memcache:
361 destroy_workqueue(kdelayd_wq);
362bad_queue:
363 return r;
364}
365
366static void __exit dm_delay_exit(void)
367{
368 int r = dm_unregister_target(&delay_target);
369
370 if (r < 0)
371 DMERR("unregister failed %d", r);
372
373 kmem_cache_destroy(delayed_cache);
374 destroy_workqueue(kdelayd_wq);
375}
376
377/* Module hooks */
378module_init(dm_delay_init);
379module_exit(dm_delay_exit);
380
381MODULE_DESCRIPTION(DM_NAME " delay target");
382MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
383MODULE_LICENSE("GPL");