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 <linux/device-mapper.h>
17
18 #define DM_MSG_PREFIX "delay"
19
20 struct delay_class {
21 struct dm_dev *dev;
22 sector_t start;
23 unsigned delay;
24 unsigned ops;
25 };
26
27 struct delay_c {
28 struct timer_list delay_timer;
29 struct mutex timer_lock;
30 struct workqueue_struct *kdelayd_wq;
31 struct work_struct flush_expired_bios;
32 struct list_head delayed_bios;
33 atomic_t may_delay;
34
35 struct delay_class read;
36 struct delay_class write;
37 struct delay_class flush;
38
39 int argc;
40 };
41
42 struct dm_delay_info {
43 struct delay_c *context;
44 struct delay_class *class;
45 struct list_head list;
46 unsigned long expires;
47 };
48
49 static DEFINE_MUTEX(delayed_bios_lock);
50
handle_delayed_timer(struct timer_list * t)51 static void handle_delayed_timer(struct timer_list *t)
52 {
53 struct delay_c *dc = from_timer(dc, t, delay_timer);
54
55 queue_work(dc->kdelayd_wq, &dc->flush_expired_bios);
56 }
57
queue_timeout(struct delay_c * dc,unsigned long expires)58 static void queue_timeout(struct delay_c *dc, unsigned long expires)
59 {
60 mutex_lock(&dc->timer_lock);
61
62 if (!timer_pending(&dc->delay_timer) || expires < dc->delay_timer.expires)
63 mod_timer(&dc->delay_timer, expires);
64
65 mutex_unlock(&dc->timer_lock);
66 }
67
flush_bios(struct bio * bio)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 dm_submit_bio_remap(bio, NULL);
76 bio = n;
77 }
78 }
79
flush_delayed_bios(struct delay_c * dc,int flush_all)80 static struct bio *flush_delayed_bios(struct delay_c *dc, int flush_all)
81 {
82 struct dm_delay_info *delayed, *next;
83 unsigned long next_expires = 0;
84 unsigned long start_timer = 0;
85 struct bio_list flush_bios = { };
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 struct bio *bio = dm_bio_from_per_bio_data(delayed,
91 sizeof(struct dm_delay_info));
92 list_del(&delayed->list);
93 bio_list_add(&flush_bios, bio);
94 delayed->class->ops--;
95 continue;
96 }
97
98 if (!start_timer) {
99 start_timer = 1;
100 next_expires = delayed->expires;
101 } else
102 next_expires = min(next_expires, delayed->expires);
103 }
104 mutex_unlock(&delayed_bios_lock);
105
106 if (start_timer)
107 queue_timeout(dc, next_expires);
108
109 return bio_list_get(&flush_bios);
110 }
111
flush_expired_bios(struct work_struct * work)112 static void flush_expired_bios(struct work_struct *work)
113 {
114 struct delay_c *dc;
115
116 dc = container_of(work, struct delay_c, flush_expired_bios);
117 flush_bios(flush_delayed_bios(dc, 0));
118 }
119
delay_dtr(struct dm_target * ti)120 static void delay_dtr(struct dm_target *ti)
121 {
122 struct delay_c *dc = ti->private;
123
124 if (dc->kdelayd_wq)
125 destroy_workqueue(dc->kdelayd_wq);
126
127 if (dc->read.dev)
128 dm_put_device(ti, dc->read.dev);
129 if (dc->write.dev)
130 dm_put_device(ti, dc->write.dev);
131 if (dc->flush.dev)
132 dm_put_device(ti, dc->flush.dev);
133
134 mutex_destroy(&dc->timer_lock);
135
136 kfree(dc);
137 }
138
delay_class_ctr(struct dm_target * ti,struct delay_class * c,char ** argv)139 static int delay_class_ctr(struct dm_target *ti, struct delay_class *c, char **argv)
140 {
141 int ret;
142 unsigned long long tmpll;
143 char dummy;
144
145 if (sscanf(argv[1], "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
146 ti->error = "Invalid device sector";
147 return -EINVAL;
148 }
149 c->start = tmpll;
150
151 if (sscanf(argv[2], "%u%c", &c->delay, &dummy) != 1) {
152 ti->error = "Invalid delay";
153 return -EINVAL;
154 }
155
156 ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &c->dev);
157 if (ret) {
158 ti->error = "Device lookup failed";
159 return ret;
160 }
161
162 return 0;
163 }
164
165 /*
166 * Mapping parameters:
167 * <device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
168 *
169 * With separate write parameters, the first set is only used for reads.
170 * Offsets are specified in sectors.
171 * Delays are specified in milliseconds.
172 */
delay_ctr(struct dm_target * ti,unsigned int argc,char ** argv)173 static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv)
174 {
175 struct delay_c *dc;
176 int ret;
177
178 if (argc != 3 && argc != 6 && argc != 9) {
179 ti->error = "Requires exactly 3, 6 or 9 arguments";
180 return -EINVAL;
181 }
182
183 dc = kzalloc(sizeof(*dc), GFP_KERNEL);
184 if (!dc) {
185 ti->error = "Cannot allocate context";
186 return -ENOMEM;
187 }
188
189 ti->private = dc;
190 timer_setup(&dc->delay_timer, handle_delayed_timer, 0);
191 INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
192 INIT_LIST_HEAD(&dc->delayed_bios);
193 mutex_init(&dc->timer_lock);
194 atomic_set(&dc->may_delay, 1);
195 dc->argc = argc;
196
197 ret = delay_class_ctr(ti, &dc->read, argv);
198 if (ret)
199 goto bad;
200
201 if (argc == 3) {
202 ret = delay_class_ctr(ti, &dc->write, argv);
203 if (ret)
204 goto bad;
205 ret = delay_class_ctr(ti, &dc->flush, argv);
206 if (ret)
207 goto bad;
208 goto out;
209 }
210
211 ret = delay_class_ctr(ti, &dc->write, argv + 3);
212 if (ret)
213 goto bad;
214 if (argc == 6) {
215 ret = delay_class_ctr(ti, &dc->flush, argv + 3);
216 if (ret)
217 goto bad;
218 goto out;
219 }
220
221 ret = delay_class_ctr(ti, &dc->flush, argv + 6);
222 if (ret)
223 goto bad;
224
225 out:
226 dc->kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0);
227 if (!dc->kdelayd_wq) {
228 ret = -EINVAL;
229 DMERR("Couldn't start kdelayd");
230 goto bad;
231 }
232
233 ti->num_flush_bios = 1;
234 ti->num_discard_bios = 1;
235 ti->accounts_remapped_io = true;
236 ti->per_io_data_size = sizeof(struct dm_delay_info);
237 return 0;
238
239 bad:
240 delay_dtr(ti);
241 return ret;
242 }
243
delay_bio(struct delay_c * dc,struct delay_class * c,struct bio * bio)244 static int delay_bio(struct delay_c *dc, struct delay_class *c, struct bio *bio)
245 {
246 struct dm_delay_info *delayed;
247 unsigned long expires = 0;
248
249 if (!c->delay || !atomic_read(&dc->may_delay))
250 return DM_MAPIO_REMAPPED;
251
252 delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info));
253
254 delayed->context = dc;
255 delayed->expires = expires = jiffies + msecs_to_jiffies(c->delay);
256
257 mutex_lock(&delayed_bios_lock);
258 c->ops++;
259 list_add_tail(&delayed->list, &dc->delayed_bios);
260 mutex_unlock(&delayed_bios_lock);
261
262 queue_timeout(dc, expires);
263
264 return DM_MAPIO_SUBMITTED;
265 }
266
delay_presuspend(struct dm_target * ti)267 static void delay_presuspend(struct dm_target *ti)
268 {
269 struct delay_c *dc = ti->private;
270
271 atomic_set(&dc->may_delay, 0);
272 del_timer_sync(&dc->delay_timer);
273 flush_bios(flush_delayed_bios(dc, 1));
274 }
275
delay_resume(struct dm_target * ti)276 static void delay_resume(struct dm_target *ti)
277 {
278 struct delay_c *dc = ti->private;
279
280 atomic_set(&dc->may_delay, 1);
281 }
282
delay_map(struct dm_target * ti,struct bio * bio)283 static int delay_map(struct dm_target *ti, struct bio *bio)
284 {
285 struct delay_c *dc = ti->private;
286 struct delay_class *c;
287 struct dm_delay_info *delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info));
288
289 if (bio_data_dir(bio) == WRITE) {
290 if (unlikely(bio->bi_opf & REQ_PREFLUSH))
291 c = &dc->flush;
292 else
293 c = &dc->write;
294 } else {
295 c = &dc->read;
296 }
297 delayed->class = c;
298 bio_set_dev(bio, c->dev->bdev);
299 bio->bi_iter.bi_sector = c->start + dm_target_offset(ti, bio->bi_iter.bi_sector);
300
301 return delay_bio(dc, c, bio);
302 }
303
304 #define DMEMIT_DELAY_CLASS(c) \
305 DMEMIT("%s %llu %u", (c)->dev->name, (unsigned long long)(c)->start, (c)->delay)
306
delay_status(struct dm_target * ti,status_type_t type,unsigned status_flags,char * result,unsigned maxlen)307 static void delay_status(struct dm_target *ti, status_type_t type,
308 unsigned status_flags, char *result, unsigned maxlen)
309 {
310 struct delay_c *dc = ti->private;
311 int sz = 0;
312
313 switch (type) {
314 case STATUSTYPE_INFO:
315 DMEMIT("%u %u %u", dc->read.ops, dc->write.ops, dc->flush.ops);
316 break;
317
318 case STATUSTYPE_TABLE:
319 DMEMIT_DELAY_CLASS(&dc->read);
320 if (dc->argc >= 6) {
321 DMEMIT(" ");
322 DMEMIT_DELAY_CLASS(&dc->write);
323 }
324 if (dc->argc >= 9) {
325 DMEMIT(" ");
326 DMEMIT_DELAY_CLASS(&dc->flush);
327 }
328 break;
329
330 case STATUSTYPE_IMA:
331 *result = '\0';
332 break;
333 }
334 }
335
delay_iterate_devices(struct dm_target * ti,iterate_devices_callout_fn fn,void * data)336 static int delay_iterate_devices(struct dm_target *ti,
337 iterate_devices_callout_fn fn, void *data)
338 {
339 struct delay_c *dc = ti->private;
340 int ret = 0;
341
342 ret = fn(ti, dc->read.dev, dc->read.start, ti->len, data);
343 if (ret)
344 goto out;
345 ret = fn(ti, dc->write.dev, dc->write.start, ti->len, data);
346 if (ret)
347 goto out;
348 ret = fn(ti, dc->flush.dev, dc->flush.start, ti->len, data);
349 if (ret)
350 goto out;
351
352 out:
353 return ret;
354 }
355
356 static struct target_type delay_target = {
357 .name = "delay",
358 .version = {1, 3, 0},
359 .features = DM_TARGET_PASSES_INTEGRITY,
360 .module = THIS_MODULE,
361 .ctr = delay_ctr,
362 .dtr = delay_dtr,
363 .map = delay_map,
364 .presuspend = delay_presuspend,
365 .resume = delay_resume,
366 .status = delay_status,
367 .iterate_devices = delay_iterate_devices,
368 };
369
dm_delay_init(void)370 static int __init dm_delay_init(void)
371 {
372 int r;
373
374 r = dm_register_target(&delay_target);
375 if (r < 0) {
376 DMERR("register failed %d", r);
377 goto bad_register;
378 }
379
380 return 0;
381
382 bad_register:
383 return r;
384 }
385
dm_delay_exit(void)386 static void __exit dm_delay_exit(void)
387 {
388 dm_unregister_target(&delay_target);
389 }
390
391 /* Module hooks */
392 module_init(dm_delay_init);
393 module_exit(dm_delay_exit);
394
395 MODULE_DESCRIPTION(DM_NAME " delay target");
396 MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
397 MODULE_LICENSE("GPL");
398