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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
20struct delay_class {
21 struct dm_dev *dev;
22 sector_t start;
23 unsigned delay;
24 unsigned ops;
25};
26
27struct 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
42struct dm_delay_info {
43 struct delay_c *context;
44 struct delay_class *class;
45 struct list_head list;
46 unsigned long expires;
47};
48
49static DEFINE_MUTEX(delayed_bios_lock);
50
51static 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
58static 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
68static 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
80static 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
112static 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
120static 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
139static 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 */
173static 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
225out:
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
239bad:
240 delay_dtr(ti);
241 return ret;
242}
243
244static 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
267static 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
276static 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
283static 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
307static 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
336static 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
352out:
353 return ret;
354}
355
356static 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
370static 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
382bad_register:
383 return r;
384}
385
386static void __exit dm_delay_exit(void)
387{
388 dm_unregister_target(&delay_target);
389}
390
391/* Module hooks */
392module_init(dm_delay_init);
393module_exit(dm_delay_exit);
394
395MODULE_DESCRIPTION(DM_NAME " delay target");
396MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
397MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2005-2007 Red Hat GmbH
4 *
5 * A target that delays reads and/or writes and can send
6 * them to different devices.
7 *
8 * This file is released under the GPL.
9 */
10
11#include <linux/module.h>
12#include <linux/init.h>
13#include <linux/blkdev.h>
14#include <linux/bio.h>
15#include <linux/slab.h>
16#include <linux/kthread.h>
17
18#include <linux/device-mapper.h>
19
20#define DM_MSG_PREFIX "delay"
21
22struct delay_class {
23 struct dm_dev *dev;
24 sector_t start;
25 unsigned int delay;
26 unsigned int ops;
27};
28
29struct delay_c {
30 struct timer_list delay_timer;
31 struct mutex process_bios_lock; /* hold while removing bios to be processed from list */
32 spinlock_t delayed_bios_lock; /* hold on all accesses to delayed_bios list */
33 struct workqueue_struct *kdelayd_wq;
34 struct work_struct flush_expired_bios;
35 struct list_head delayed_bios;
36 struct task_struct *worker;
37 bool may_delay;
38
39 struct delay_class read;
40 struct delay_class write;
41 struct delay_class flush;
42
43 int argc;
44};
45
46struct dm_delay_info {
47 struct delay_c *context;
48 struct delay_class *class;
49 struct list_head list;
50 unsigned long expires;
51};
52
53static void handle_delayed_timer(struct timer_list *t)
54{
55 struct delay_c *dc = from_timer(dc, t, delay_timer);
56
57 queue_work(dc->kdelayd_wq, &dc->flush_expired_bios);
58}
59
60static void queue_timeout(struct delay_c *dc, unsigned long expires)
61{
62 timer_reduce(&dc->delay_timer, expires);
63}
64
65static inline bool delay_is_fast(struct delay_c *dc)
66{
67 return !!dc->worker;
68}
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 dm_submit_bio_remap(bio, NULL);
78 bio = n;
79 }
80}
81
82static void flush_delayed_bios(struct delay_c *dc, bool flush_all)
83{
84 struct dm_delay_info *delayed, *next;
85 struct bio_list flush_bio_list;
86 LIST_HEAD(local_list);
87 unsigned long next_expires = 0;
88 bool start_timer = false;
89 bio_list_init(&flush_bio_list);
90
91 mutex_lock(&dc->process_bios_lock);
92 spin_lock(&dc->delayed_bios_lock);
93 list_replace_init(&dc->delayed_bios, &local_list);
94 spin_unlock(&dc->delayed_bios_lock);
95 list_for_each_entry_safe(delayed, next, &local_list, list) {
96 cond_resched();
97 if (flush_all || time_after_eq(jiffies, delayed->expires)) {
98 struct bio *bio = dm_bio_from_per_bio_data(delayed,
99 sizeof(struct dm_delay_info));
100 list_del(&delayed->list);
101 bio_list_add(&flush_bio_list, bio);
102 delayed->class->ops--;
103 continue;
104 }
105
106 if (!delay_is_fast(dc)) {
107 if (!start_timer) {
108 start_timer = true;
109 next_expires = delayed->expires;
110 } else {
111 next_expires = min(next_expires, delayed->expires);
112 }
113 }
114 }
115 spin_lock(&dc->delayed_bios_lock);
116 list_splice(&local_list, &dc->delayed_bios);
117 spin_unlock(&dc->delayed_bios_lock);
118 mutex_unlock(&dc->process_bios_lock);
119
120 if (start_timer)
121 queue_timeout(dc, next_expires);
122
123 flush_bios(bio_list_get(&flush_bio_list));
124}
125
126static int flush_worker_fn(void *data)
127{
128 struct delay_c *dc = data;
129
130 while (!kthread_should_stop()) {
131 flush_delayed_bios(dc, false);
132 spin_lock(&dc->delayed_bios_lock);
133 if (unlikely(list_empty(&dc->delayed_bios))) {
134 set_current_state(TASK_INTERRUPTIBLE);
135 spin_unlock(&dc->delayed_bios_lock);
136 schedule();
137 } else {
138 spin_unlock(&dc->delayed_bios_lock);
139 cond_resched();
140 }
141 }
142
143 return 0;
144}
145
146static void flush_expired_bios(struct work_struct *work)
147{
148 struct delay_c *dc;
149
150 dc = container_of(work, struct delay_c, flush_expired_bios);
151 flush_delayed_bios(dc, false);
152}
153
154static void delay_dtr(struct dm_target *ti)
155{
156 struct delay_c *dc = ti->private;
157
158 if (dc->kdelayd_wq) {
159 timer_shutdown_sync(&dc->delay_timer);
160 destroy_workqueue(dc->kdelayd_wq);
161 }
162
163 if (dc->read.dev)
164 dm_put_device(ti, dc->read.dev);
165 if (dc->write.dev)
166 dm_put_device(ti, dc->write.dev);
167 if (dc->flush.dev)
168 dm_put_device(ti, dc->flush.dev);
169 if (dc->worker)
170 kthread_stop(dc->worker);
171
172 mutex_destroy(&dc->process_bios_lock);
173
174 kfree(dc);
175}
176
177static int delay_class_ctr(struct dm_target *ti, struct delay_class *c, char **argv)
178{
179 int ret;
180 unsigned long long tmpll;
181 char dummy;
182
183 if (sscanf(argv[1], "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
184 ti->error = "Invalid device sector";
185 return -EINVAL;
186 }
187 c->start = tmpll;
188
189 if (sscanf(argv[2], "%u%c", &c->delay, &dummy) != 1) {
190 ti->error = "Invalid delay";
191 return -EINVAL;
192 }
193
194 ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &c->dev);
195 if (ret) {
196 ti->error = "Device lookup failed";
197 return ret;
198 }
199
200 return 0;
201}
202
203/*
204 * Mapping parameters:
205 * <device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
206 *
207 * With separate write parameters, the first set is only used for reads.
208 * Offsets are specified in sectors.
209 * Delays are specified in milliseconds.
210 */
211static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv)
212{
213 struct delay_c *dc;
214 int ret;
215 unsigned int max_delay;
216
217 if (argc != 3 && argc != 6 && argc != 9) {
218 ti->error = "Requires exactly 3, 6 or 9 arguments";
219 return -EINVAL;
220 }
221
222 dc = kzalloc(sizeof(*dc), GFP_KERNEL);
223 if (!dc) {
224 ti->error = "Cannot allocate context";
225 return -ENOMEM;
226 }
227
228 ti->private = dc;
229 INIT_LIST_HEAD(&dc->delayed_bios);
230 mutex_init(&dc->process_bios_lock);
231 spin_lock_init(&dc->delayed_bios_lock);
232 dc->may_delay = true;
233 dc->argc = argc;
234
235 ret = delay_class_ctr(ti, &dc->read, argv);
236 if (ret)
237 goto bad;
238 max_delay = dc->read.delay;
239
240 if (argc == 3) {
241 ret = delay_class_ctr(ti, &dc->write, argv);
242 if (ret)
243 goto bad;
244 ret = delay_class_ctr(ti, &dc->flush, argv);
245 if (ret)
246 goto bad;
247 goto out;
248 }
249
250 ret = delay_class_ctr(ti, &dc->write, argv + 3);
251 if (ret)
252 goto bad;
253 max_delay = max(max_delay, dc->write.delay);
254
255 if (argc == 6) {
256 ret = delay_class_ctr(ti, &dc->flush, argv + 3);
257 if (ret)
258 goto bad;
259 goto out;
260 }
261
262 ret = delay_class_ctr(ti, &dc->flush, argv + 6);
263 if (ret)
264 goto bad;
265 max_delay = max(max_delay, dc->flush.delay);
266
267out:
268 if (max_delay < 50) {
269 /*
270 * In case of small requested delays, use kthread instead of
271 * timers and workqueue to achieve better latency.
272 */
273 dc->worker = kthread_run(&flush_worker_fn, dc, "dm-delay-flush-worker");
274 if (IS_ERR(dc->worker)) {
275 ret = PTR_ERR(dc->worker);
276 dc->worker = NULL;
277 goto bad;
278 }
279 } else {
280 timer_setup(&dc->delay_timer, handle_delayed_timer, 0);
281 INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
282 dc->kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0);
283 if (!dc->kdelayd_wq) {
284 ret = -EINVAL;
285 DMERR("Couldn't start kdelayd");
286 goto bad;
287 }
288 }
289
290 ti->num_flush_bios = 1;
291 ti->num_discard_bios = 1;
292 ti->accounts_remapped_io = true;
293 ti->per_io_data_size = sizeof(struct dm_delay_info);
294 return 0;
295
296bad:
297 delay_dtr(ti);
298 return ret;
299}
300
301static int delay_bio(struct delay_c *dc, struct delay_class *c, struct bio *bio)
302{
303 struct dm_delay_info *delayed;
304 unsigned long expires = 0;
305
306 if (!c->delay)
307 return DM_MAPIO_REMAPPED;
308
309 delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info));
310
311 delayed->context = dc;
312 delayed->expires = expires = jiffies + msecs_to_jiffies(c->delay);
313
314 spin_lock(&dc->delayed_bios_lock);
315 if (unlikely(!dc->may_delay)) {
316 spin_unlock(&dc->delayed_bios_lock);
317 return DM_MAPIO_REMAPPED;
318 }
319 c->ops++;
320 list_add_tail(&delayed->list, &dc->delayed_bios);
321 spin_unlock(&dc->delayed_bios_lock);
322
323 if (delay_is_fast(dc))
324 wake_up_process(dc->worker);
325 else
326 queue_timeout(dc, expires);
327
328 return DM_MAPIO_SUBMITTED;
329}
330
331static void delay_presuspend(struct dm_target *ti)
332{
333 struct delay_c *dc = ti->private;
334
335 spin_lock(&dc->delayed_bios_lock);
336 dc->may_delay = false;
337 spin_unlock(&dc->delayed_bios_lock);
338
339 if (!delay_is_fast(dc))
340 timer_delete(&dc->delay_timer);
341 flush_delayed_bios(dc, true);
342}
343
344static void delay_resume(struct dm_target *ti)
345{
346 struct delay_c *dc = ti->private;
347
348 dc->may_delay = true;
349}
350
351static int delay_map(struct dm_target *ti, struct bio *bio)
352{
353 struct delay_c *dc = ti->private;
354 struct delay_class *c;
355 struct dm_delay_info *delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info));
356
357 if (bio_data_dir(bio) == WRITE) {
358 if (unlikely(bio->bi_opf & REQ_PREFLUSH))
359 c = &dc->flush;
360 else
361 c = &dc->write;
362 } else {
363 c = &dc->read;
364 }
365 delayed->class = c;
366 bio_set_dev(bio, c->dev->bdev);
367 bio->bi_iter.bi_sector = c->start + dm_target_offset(ti, bio->bi_iter.bi_sector);
368
369 return delay_bio(dc, c, bio);
370}
371
372#define DMEMIT_DELAY_CLASS(c) \
373 DMEMIT("%s %llu %u", (c)->dev->name, (unsigned long long)(c)->start, (c)->delay)
374
375static void delay_status(struct dm_target *ti, status_type_t type,
376 unsigned int status_flags, char *result, unsigned int maxlen)
377{
378 struct delay_c *dc = ti->private;
379 int sz = 0;
380
381 switch (type) {
382 case STATUSTYPE_INFO:
383 DMEMIT("%u %u %u", dc->read.ops, dc->write.ops, dc->flush.ops);
384 break;
385
386 case STATUSTYPE_TABLE:
387 DMEMIT_DELAY_CLASS(&dc->read);
388 if (dc->argc >= 6) {
389 DMEMIT(" ");
390 DMEMIT_DELAY_CLASS(&dc->write);
391 }
392 if (dc->argc >= 9) {
393 DMEMIT(" ");
394 DMEMIT_DELAY_CLASS(&dc->flush);
395 }
396 break;
397
398 case STATUSTYPE_IMA:
399 *result = '\0';
400 break;
401 }
402}
403
404static int delay_iterate_devices(struct dm_target *ti,
405 iterate_devices_callout_fn fn, void *data)
406{
407 struct delay_c *dc = ti->private;
408 int ret = 0;
409
410 ret = fn(ti, dc->read.dev, dc->read.start, ti->len, data);
411 if (ret)
412 goto out;
413 ret = fn(ti, dc->write.dev, dc->write.start, ti->len, data);
414 if (ret)
415 goto out;
416 ret = fn(ti, dc->flush.dev, dc->flush.start, ti->len, data);
417 if (ret)
418 goto out;
419
420out:
421 return ret;
422}
423
424static struct target_type delay_target = {
425 .name = "delay",
426 .version = {1, 4, 0},
427 .features = DM_TARGET_PASSES_INTEGRITY,
428 .module = THIS_MODULE,
429 .ctr = delay_ctr,
430 .dtr = delay_dtr,
431 .map = delay_map,
432 .presuspend = delay_presuspend,
433 .resume = delay_resume,
434 .status = delay_status,
435 .iterate_devices = delay_iterate_devices,
436};
437module_dm(delay);
438
439MODULE_DESCRIPTION(DM_NAME " delay target");
440MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
441MODULE_LICENSE("GPL");