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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 generic_make_request(bio);
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
167
168
169
170
171
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->per_io_data_size = sizeof(struct dm_delay_info);
236 return 0;
237
238bad:
239 delay_dtr(ti);
240 return ret;
241}
242
243static int delay_bio(struct delay_c *dc, struct delay_class *c, struct bio *bio)
244{
245 struct dm_delay_info *delayed;
246 unsigned long expires = 0;
247
248 if (!c->delay || !atomic_read(&dc->may_delay))
249 return DM_MAPIO_REMAPPED;
250
251 delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info));
252
253 delayed->context = dc;
254 delayed->expires = expires = jiffies + msecs_to_jiffies(c->delay);
255
256 mutex_lock(&delayed_bios_lock);
257 c->ops++;
258 list_add_tail(&delayed->list, &dc->delayed_bios);
259 mutex_unlock(&delayed_bios_lock);
260
261 queue_timeout(dc, expires);
262
263 return DM_MAPIO_SUBMITTED;
264}
265
266static void delay_presuspend(struct dm_target *ti)
267{
268 struct delay_c *dc = ti->private;
269
270 atomic_set(&dc->may_delay, 0);
271 del_timer_sync(&dc->delay_timer);
272 flush_bios(flush_delayed_bios(dc, 1));
273}
274
275static void delay_resume(struct dm_target *ti)
276{
277 struct delay_c *dc = ti->private;
278
279 atomic_set(&dc->may_delay, 1);
280}
281
282static int delay_map(struct dm_target *ti, struct bio *bio)
283{
284 struct delay_c *dc = ti->private;
285 struct delay_class *c;
286 struct dm_delay_info *delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info));
287
288 if (bio_data_dir(bio) == WRITE) {
289 if (unlikely(bio->bi_opf & REQ_PREFLUSH))
290 c = &dc->flush;
291 else
292 c = &dc->write;
293 } else {
294 c = &dc->read;
295 }
296 delayed->class = c;
297 bio_set_dev(bio, c->dev->bdev);
298 if (bio_sectors(bio))
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}
331
332static int delay_iterate_devices(struct dm_target *ti,
333 iterate_devices_callout_fn fn, void *data)
334{
335 struct delay_c *dc = ti->private;
336 int ret = 0;
337
338 ret = fn(ti, dc->read.dev, dc->read.start, ti->len, data);
339 if (ret)
340 goto out;
341 ret = fn(ti, dc->write.dev, dc->write.start, ti->len, data);
342 if (ret)
343 goto out;
344 ret = fn(ti, dc->flush.dev, dc->flush.start, ti->len, data);
345 if (ret)
346 goto out;
347
348out:
349 return ret;
350}
351
352static struct target_type delay_target = {
353 .name = "delay",
354 .version = {1, 2, 1},
355 .features = DM_TARGET_PASSES_INTEGRITY,
356 .module = THIS_MODULE,
357 .ctr = delay_ctr,
358 .dtr = delay_dtr,
359 .map = delay_map,
360 .presuspend = delay_presuspend,
361 .resume = delay_resume,
362 .status = delay_status,
363 .iterate_devices = delay_iterate_devices,
364};
365
366static int __init dm_delay_init(void)
367{
368 int r;
369
370 r = dm_register_target(&delay_target);
371 if (r < 0) {
372 DMERR("register failed %d", r);
373 goto bad_register;
374 }
375
376 return 0;
377
378bad_register:
379 return r;
380}
381
382static void __exit dm_delay_exit(void)
383{
384 dm_unregister_target(&delay_target);
385}
386
387
388module_init(dm_delay_init);
389module_exit(dm_delay_exit);
390
391MODULE_DESCRIPTION(DM_NAME " delay target");
392MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
393MODULE_LICENSE("GPL");
394
