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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 | ||
16 | #include "dm.h" | |
17 | #include "dm-bio-list.h" | |
18 | ||
19 | #define DM_MSG_PREFIX "delay" | |
20 | ||
21 | struct delay_c { | |
22 | struct timer_list delay_timer; | |
ac818646 | 23 | struct mutex timer_lock; |
26b9f228 HM |
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 | ||
028867ac | 40 | struct dm_delay_info { |
26b9f228 HM |
41 | struct delay_c *context; |
42 | struct list_head list; | |
43 | struct bio *bio; | |
44 | unsigned long expires; | |
45 | }; | |
46 | ||
47 | static DEFINE_MUTEX(delayed_bios_lock); | |
48 | ||
49 | static struct workqueue_struct *kdelayd_wq; | |
50 | static struct kmem_cache *delayed_cache; | |
51 | ||
52 | static 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 | ||
59 | static void queue_timeout(struct delay_c *dc, unsigned long expires) | |
60 | { | |
ac818646 | 61 | mutex_lock(&dc->timer_lock); |
26b9f228 HM |
62 | |
63 | if (!timer_pending(&dc->delay_timer) || expires < dc->delay_timer.expires) | |
64 | mod_timer(&dc->delay_timer, expires); | |
65 | ||
ac818646 | 66 | mutex_unlock(&dc->timer_lock); |
26b9f228 HM |
67 | } |
68 | ||
69 | static 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 | ||
81 | static struct bio *flush_delayed_bios(struct delay_c *dc, int flush_all) | |
82 | { | |
028867ac | 83 | struct dm_delay_info *delayed, *next; |
26b9f228 HM |
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 | ||
116 | static 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 | */ | |
131 | static 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 | ||
189 | out: | |
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 | ||
ac818646 | 196 | setup_timer(&dc->delay_timer, handle_delayed_timer, (unsigned long)dc); |
26b9f228 HM |
197 | |
198 | INIT_WORK(&dc->flush_expired_bios, flush_expired_bios); | |
199 | INIT_LIST_HEAD(&dc->delayed_bios); | |
ac818646 | 200 | mutex_init(&dc->timer_lock); |
26b9f228 HM |
201 | atomic_set(&dc->may_delay, 1); |
202 | ||
203 | ti->private = dc; | |
204 | return 0; | |
205 | ||
206 | bad: | |
207 | kfree(dc); | |
208 | return -EINVAL; | |
209 | } | |
210 | ||
211 | static void delay_dtr(struct dm_target *ti) | |
212 | { | |
213 | struct delay_c *dc = ti->private; | |
214 | ||
215 | flush_workqueue(kdelayd_wq); | |
216 | ||
217 | dm_put_device(ti, dc->dev_read); | |
218 | ||
219 | if (dc->dev_write) | |
220 | dm_put_device(ti, dc->dev_write); | |
221 | ||
222 | mempool_destroy(dc->delayed_pool); | |
223 | kfree(dc); | |
224 | } | |
225 | ||
226 | static int delay_bio(struct delay_c *dc, int delay, struct bio *bio) | |
227 | { | |
028867ac | 228 | struct dm_delay_info *delayed; |
26b9f228 HM |
229 | unsigned long expires = 0; |
230 | ||
231 | if (!delay || !atomic_read(&dc->may_delay)) | |
232 | return 1; | |
233 | ||
234 | delayed = mempool_alloc(dc->delayed_pool, GFP_NOIO); | |
235 | ||
236 | delayed->context = dc; | |
237 | delayed->bio = bio; | |
238 | delayed->expires = expires = jiffies + (delay * HZ / 1000); | |
239 | ||
240 | mutex_lock(&delayed_bios_lock); | |
241 | ||
242 | if (bio_data_dir(bio) == WRITE) | |
243 | dc->writes++; | |
244 | else | |
245 | dc->reads++; | |
246 | ||
247 | list_add_tail(&delayed->list, &dc->delayed_bios); | |
248 | ||
249 | mutex_unlock(&delayed_bios_lock); | |
250 | ||
251 | queue_timeout(dc, expires); | |
252 | ||
253 | return 0; | |
254 | } | |
255 | ||
256 | static void delay_presuspend(struct dm_target *ti) | |
257 | { | |
258 | struct delay_c *dc = ti->private; | |
259 | ||
260 | atomic_set(&dc->may_delay, 0); | |
261 | del_timer_sync(&dc->delay_timer); | |
262 | flush_bios(flush_delayed_bios(dc, 1)); | |
263 | } | |
264 | ||
265 | static void delay_resume(struct dm_target *ti) | |
266 | { | |
267 | struct delay_c *dc = ti->private; | |
268 | ||
269 | atomic_set(&dc->may_delay, 1); | |
270 | } | |
271 | ||
272 | static int delay_map(struct dm_target *ti, struct bio *bio, | |
273 | union map_info *map_context) | |
274 | { | |
275 | struct delay_c *dc = ti->private; | |
276 | ||
277 | if ((bio_data_dir(bio) == WRITE) && (dc->dev_write)) { | |
278 | bio->bi_bdev = dc->dev_write->bdev; | |
279 | bio->bi_sector = dc->start_write + | |
280 | (bio->bi_sector - ti->begin); | |
281 | ||
282 | return delay_bio(dc, dc->write_delay, bio); | |
283 | } | |
284 | ||
285 | bio->bi_bdev = dc->dev_read->bdev; | |
286 | bio->bi_sector = dc->start_read + | |
287 | (bio->bi_sector - ti->begin); | |
288 | ||
289 | return delay_bio(dc, dc->read_delay, bio); | |
290 | } | |
291 | ||
292 | static int delay_status(struct dm_target *ti, status_type_t type, | |
293 | char *result, unsigned maxlen) | |
294 | { | |
295 | struct delay_c *dc = ti->private; | |
296 | int sz = 0; | |
297 | ||
298 | switch (type) { | |
299 | case STATUSTYPE_INFO: | |
300 | DMEMIT("%u %u", dc->reads, dc->writes); | |
301 | break; | |
302 | ||
303 | case STATUSTYPE_TABLE: | |
304 | DMEMIT("%s %llu %u", dc->dev_read->name, | |
305 | (unsigned long long) dc->start_read, | |
306 | dc->read_delay); | |
307 | if (dc->dev_write) | |
308 | DMEMIT("%s %llu %u", dc->dev_write->name, | |
309 | (unsigned long long) dc->start_write, | |
310 | dc->write_delay); | |
311 | break; | |
312 | } | |
313 | ||
314 | return 0; | |
315 | } | |
316 | ||
317 | static struct target_type delay_target = { | |
318 | .name = "delay", | |
319 | .version = {1, 0, 2}, | |
320 | .module = THIS_MODULE, | |
321 | .ctr = delay_ctr, | |
322 | .dtr = delay_dtr, | |
323 | .map = delay_map, | |
324 | .presuspend = delay_presuspend, | |
325 | .resume = delay_resume, | |
326 | .status = delay_status, | |
327 | }; | |
328 | ||
329 | static int __init dm_delay_init(void) | |
330 | { | |
331 | int r = -ENOMEM; | |
332 | ||
333 | kdelayd_wq = create_workqueue("kdelayd"); | |
334 | if (!kdelayd_wq) { | |
335 | DMERR("Couldn't start kdelayd"); | |
336 | goto bad_queue; | |
337 | } | |
338 | ||
028867ac | 339 | delayed_cache = KMEM_CACHE(dm_delay_info, 0); |
26b9f228 HM |
340 | if (!delayed_cache) { |
341 | DMERR("Couldn't create delayed bio cache."); | |
342 | goto bad_memcache; | |
343 | } | |
344 | ||
345 | r = dm_register_target(&delay_target); | |
346 | if (r < 0) { | |
347 | DMERR("register failed %d", r); | |
348 | goto bad_register; | |
349 | } | |
350 | ||
351 | return 0; | |
352 | ||
353 | bad_register: | |
354 | kmem_cache_destroy(delayed_cache); | |
355 | bad_memcache: | |
356 | destroy_workqueue(kdelayd_wq); | |
357 | bad_queue: | |
358 | return r; | |
359 | } | |
360 | ||
361 | static void __exit dm_delay_exit(void) | |
362 | { | |
363 | int r = dm_unregister_target(&delay_target); | |
364 | ||
365 | if (r < 0) | |
366 | DMERR("unregister failed %d", r); | |
367 | ||
368 | kmem_cache_destroy(delayed_cache); | |
369 | destroy_workqueue(kdelayd_wq); | |
370 | } | |
371 | ||
372 | /* Module hooks */ | |
373 | module_init(dm_delay_init); | |
374 | module_exit(dm_delay_exit); | |
375 | ||
376 | MODULE_DESCRIPTION(DM_NAME " delay target"); | |
377 | MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>"); | |
378 | MODULE_LICENSE("GPL"); |