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26b9f228 HM |
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 | ||
586e80e6 MP |
16 | #include <linux/device-mapper.h> |
17 | ||
26b9f228 HM |
18 | #define DM_MSG_PREFIX "delay" |
19 | ||
20 | struct delay_c { | |
21 | struct timer_list delay_timer; | |
ac818646 | 22 | struct mutex timer_lock; |
26b9f228 HM |
23 | struct work_struct flush_expired_bios; |
24 | struct list_head delayed_bios; | |
25 | atomic_t may_delay; | |
26 | mempool_t *delayed_pool; | |
27 | ||
28 | struct dm_dev *dev_read; | |
29 | sector_t start_read; | |
30 | unsigned read_delay; | |
31 | unsigned reads; | |
32 | ||
33 | struct dm_dev *dev_write; | |
34 | sector_t start_write; | |
35 | unsigned write_delay; | |
36 | unsigned writes; | |
37 | }; | |
38 | ||
028867ac | 39 | struct dm_delay_info { |
26b9f228 HM |
40 | struct delay_c *context; |
41 | struct list_head list; | |
42 | struct bio *bio; | |
43 | unsigned long expires; | |
44 | }; | |
45 | ||
46 | static DEFINE_MUTEX(delayed_bios_lock); | |
47 | ||
48 | static struct workqueue_struct *kdelayd_wq; | |
49 | static struct kmem_cache *delayed_cache; | |
50 | ||
51 | static void handle_delayed_timer(unsigned long data) | |
52 | { | |
53 | struct delay_c *dc = (struct delay_c *)data; | |
54 | ||
55 | queue_work(kdelayd_wq, &dc->flush_expired_bios); | |
56 | } | |
57 | ||
58 | static void queue_timeout(struct delay_c *dc, unsigned long expires) | |
59 | { | |
ac818646 | 60 | mutex_lock(&dc->timer_lock); |
26b9f228 HM |
61 | |
62 | if (!timer_pending(&dc->delay_timer) || expires < dc->delay_timer.expires) | |
63 | mod_timer(&dc->delay_timer, expires); | |
64 | ||
ac818646 | 65 | mutex_unlock(&dc->timer_lock); |
26b9f228 HM |
66 | } |
67 | ||
68 | static void flush_bios(struct bio *bio) | |
69 | { | |
70 | struct bio *n; | |
71 | ||
72 | while (bio) { | |
73 | n = bio->bi_next; | |
74 | bio->bi_next = NULL; | |
75 | generic_make_request(bio); | |
76 | bio = n; | |
77 | } | |
78 | } | |
79 | ||
80 | static struct bio *flush_delayed_bios(struct delay_c *dc, int flush_all) | |
81 | { | |
028867ac | 82 | struct dm_delay_info *delayed, *next; |
26b9f228 HM |
83 | unsigned long next_expires = 0; |
84 | int start_timer = 0; | |
051814c6 | 85 | struct bio_list flush_bios = { }; |
26b9f228 HM |
86 | |
87 | mutex_lock(&delayed_bios_lock); | |
88 | list_for_each_entry_safe(delayed, next, &dc->delayed_bios, list) { | |
89 | if (flush_all || time_after_eq(jiffies, delayed->expires)) { | |
90 | list_del(&delayed->list); | |
91 | bio_list_add(&flush_bios, delayed->bio); | |
92 | if ((bio_data_dir(delayed->bio) == WRITE)) | |
93 | delayed->context->writes--; | |
94 | else | |
95 | delayed->context->reads--; | |
96 | mempool_free(delayed, dc->delayed_pool); | |
97 | continue; | |
98 | } | |
99 | ||
100 | if (!start_timer) { | |
101 | start_timer = 1; | |
102 | next_expires = delayed->expires; | |
103 | } else | |
104 | next_expires = min(next_expires, delayed->expires); | |
105 | } | |
106 | ||
107 | mutex_unlock(&delayed_bios_lock); | |
108 | ||
109 | if (start_timer) | |
110 | queue_timeout(dc, next_expires); | |
111 | ||
112 | return bio_list_get(&flush_bios); | |
113 | } | |
114 | ||
115 | static void flush_expired_bios(struct work_struct *work) | |
116 | { | |
117 | struct delay_c *dc; | |
118 | ||
119 | dc = container_of(work, struct delay_c, flush_expired_bios); | |
120 | flush_bios(flush_delayed_bios(dc, 0)); | |
121 | } | |
122 | ||
123 | /* | |
124 | * Mapping parameters: | |
125 | * <device> <offset> <delay> [<write_device> <write_offset> <write_delay>] | |
126 | * | |
127 | * With separate write parameters, the first set is only used for reads. | |
128 | * Delays are specified in milliseconds. | |
129 | */ | |
130 | static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv) | |
131 | { | |
132 | struct delay_c *dc; | |
133 | unsigned long long tmpll; | |
134 | ||
135 | if (argc != 3 && argc != 6) { | |
136 | ti->error = "requires exactly 3 or 6 arguments"; | |
137 | return -EINVAL; | |
138 | } | |
139 | ||
140 | dc = kmalloc(sizeof(*dc), GFP_KERNEL); | |
141 | if (!dc) { | |
142 | ti->error = "Cannot allocate context"; | |
143 | return -ENOMEM; | |
144 | } | |
145 | ||
146 | dc->reads = dc->writes = 0; | |
147 | ||
148 | if (sscanf(argv[1], "%llu", &tmpll) != 1) { | |
149 | ti->error = "Invalid device sector"; | |
150 | goto bad; | |
151 | } | |
152 | dc->start_read = tmpll; | |
153 | ||
154 | if (sscanf(argv[2], "%u", &dc->read_delay) != 1) { | |
155 | ti->error = "Invalid delay"; | |
156 | goto bad; | |
157 | } | |
158 | ||
8215d6ec NK |
159 | if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), |
160 | &dc->dev_read)) { | |
26b9f228 HM |
161 | ti->error = "Device lookup failed"; |
162 | goto bad; | |
163 | } | |
164 | ||
2e64a0f9 DM |
165 | dc->dev_write = NULL; |
166 | if (argc == 3) | |
26b9f228 | 167 | goto out; |
26b9f228 HM |
168 | |
169 | if (sscanf(argv[4], "%llu", &tmpll) != 1) { | |
170 | ti->error = "Invalid write device sector"; | |
2e64a0f9 | 171 | goto bad_dev_read; |
26b9f228 HM |
172 | } |
173 | dc->start_write = tmpll; | |
174 | ||
175 | if (sscanf(argv[5], "%u", &dc->write_delay) != 1) { | |
176 | ti->error = "Invalid write delay"; | |
2e64a0f9 | 177 | goto bad_dev_read; |
26b9f228 HM |
178 | } |
179 | ||
8215d6ec NK |
180 | if (dm_get_device(ti, argv[3], dm_table_get_mode(ti->table), |
181 | &dc->dev_write)) { | |
26b9f228 | 182 | ti->error = "Write device lookup failed"; |
2e64a0f9 | 183 | goto bad_dev_read; |
26b9f228 HM |
184 | } |
185 | ||
186 | out: | |
187 | dc->delayed_pool = mempool_create_slab_pool(128, delayed_cache); | |
188 | if (!dc->delayed_pool) { | |
189 | DMERR("Couldn't create delayed bio pool."); | |
2e64a0f9 | 190 | goto bad_dev_write; |
26b9f228 HM |
191 | } |
192 | ||
ac818646 | 193 | setup_timer(&dc->delay_timer, handle_delayed_timer, (unsigned long)dc); |
26b9f228 HM |
194 | |
195 | INIT_WORK(&dc->flush_expired_bios, flush_expired_bios); | |
196 | INIT_LIST_HEAD(&dc->delayed_bios); | |
ac818646 | 197 | mutex_init(&dc->timer_lock); |
26b9f228 HM |
198 | atomic_set(&dc->may_delay, 1); |
199 | ||
c927259e | 200 | ti->num_flush_requests = 1; |
3fd5d480 | 201 | ti->num_discard_requests = 1; |
26b9f228 HM |
202 | ti->private = dc; |
203 | return 0; | |
204 | ||
2e64a0f9 DM |
205 | bad_dev_write: |
206 | if (dc->dev_write) | |
207 | dm_put_device(ti, dc->dev_write); | |
208 | bad_dev_read: | |
209 | dm_put_device(ti, dc->dev_read); | |
26b9f228 HM |
210 | bad: |
211 | kfree(dc); | |
212 | return -EINVAL; | |
213 | } | |
214 | ||
215 | static 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 | ||
230 | static int delay_bio(struct delay_c *dc, int delay, struct bio *bio) | |
231 | { | |
028867ac | 232 | struct dm_delay_info *delayed; |
26b9f228 HM |
233 | 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 | ||
260 | static 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 | ||
269 | static 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 | ||
276 | static 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; | |
c927259e MP |
283 | if (bio_sectors(bio)) |
284 | bio->bi_sector = dc->start_write + | |
b441a262 | 285 | dm_target_offset(ti, bio->bi_sector); |
26b9f228 HM |
286 | |
287 | return delay_bio(dc, dc->write_delay, bio); | |
288 | } | |
289 | ||
290 | bio->bi_bdev = dc->dev_read->bdev; | |
b441a262 | 291 | bio->bi_sector = dc->start_read + dm_target_offset(ti, bio->bi_sector); |
26b9f228 HM |
292 | |
293 | return delay_bio(dc, dc->read_delay, bio); | |
294 | } | |
295 | ||
296 | static 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) | |
79662d1e | 312 | DMEMIT(" %s %llu %u", dc->dev_write->name, |
26b9f228 HM |
313 | (unsigned long long) dc->start_write, |
314 | dc->write_delay); | |
315 | break; | |
316 | } | |
317 | ||
318 | return 0; | |
319 | } | |
320 | ||
af4874e0 MS |
321 | static int delay_iterate_devices(struct dm_target *ti, |
322 | iterate_devices_callout_fn fn, void *data) | |
323 | { | |
324 | struct delay_c *dc = ti->private; | |
325 | int ret = 0; | |
326 | ||
5dea271b | 327 | ret = fn(ti, dc->dev_read, dc->start_read, ti->len, data); |
af4874e0 MS |
328 | if (ret) |
329 | goto out; | |
330 | ||
331 | if (dc->dev_write) | |
5dea271b | 332 | ret = fn(ti, dc->dev_write, dc->start_write, ti->len, data); |
af4874e0 MS |
333 | |
334 | out: | |
335 | return ret; | |
336 | } | |
337 | ||
26b9f228 HM |
338 | static struct target_type delay_target = { |
339 | .name = "delay", | |
af4874e0 | 340 | .version = {1, 1, 0}, |
26b9f228 HM |
341 | .module = THIS_MODULE, |
342 | .ctr = delay_ctr, | |
343 | .dtr = delay_dtr, | |
344 | .map = delay_map, | |
345 | .presuspend = delay_presuspend, | |
346 | .resume = delay_resume, | |
347 | .status = delay_status, | |
af4874e0 | 348 | .iterate_devices = delay_iterate_devices, |
26b9f228 HM |
349 | }; |
350 | ||
351 | static int __init dm_delay_init(void) | |
352 | { | |
353 | int r = -ENOMEM; | |
354 | ||
4d4d66ab | 355 | kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0); |
26b9f228 HM |
356 | if (!kdelayd_wq) { |
357 | DMERR("Couldn't start kdelayd"); | |
358 | goto bad_queue; | |
359 | } | |
360 | ||
028867ac | 361 | delayed_cache = KMEM_CACHE(dm_delay_info, 0); |
26b9f228 HM |
362 | if (!delayed_cache) { |
363 | DMERR("Couldn't create delayed bio cache."); | |
364 | goto bad_memcache; | |
365 | } | |
366 | ||
367 | r = dm_register_target(&delay_target); | |
368 | if (r < 0) { | |
369 | DMERR("register failed %d", r); | |
370 | goto bad_register; | |
371 | } | |
372 | ||
373 | return 0; | |
374 | ||
375 | bad_register: | |
376 | kmem_cache_destroy(delayed_cache); | |
377 | bad_memcache: | |
378 | destroy_workqueue(kdelayd_wq); | |
379 | bad_queue: | |
380 | return r; | |
381 | } | |
382 | ||
383 | static void __exit dm_delay_exit(void) | |
384 | { | |
10d3bd09 | 385 | dm_unregister_target(&delay_target); |
26b9f228 HM |
386 | kmem_cache_destroy(delayed_cache); |
387 | destroy_workqueue(kdelayd_wq); | |
388 | } | |
389 | ||
390 | /* Module hooks */ | |
391 | module_init(dm_delay_init); | |
392 | module_exit(dm_delay_exit); | |
393 | ||
394 | MODULE_DESCRIPTION(DM_NAME " delay target"); | |
395 | MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>"); | |
396 | MODULE_LICENSE("GPL"); |