2 * Copyright (C) 2005-2007 Red Hat GmbH
4 * A target that delays reads and/or writes and can send
5 * them to different devices.
7 * This file is released under the GPL.
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>
16 #include <linux/device-mapper.h>
18 #define DM_MSG_PREFIX "delay"
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;
35 struct delay_class read;
36 struct delay_class write;
37 struct delay_class flush;
42 struct dm_delay_info {
43 struct delay_c *context;
44 struct delay_class *class;
45 struct list_head list;
46 unsigned long expires;
49 static DEFINE_MUTEX(delayed_bios_lock);
51 static void handle_delayed_timer(struct timer_list *t)
53 struct delay_c *dc = from_timer(dc, t, delay_timer);
55 queue_work(dc->kdelayd_wq, &dc->flush_expired_bios);
58 static void queue_timeout(struct delay_c *dc, unsigned long expires)
60 mutex_lock(&dc->timer_lock);
62 if (!timer_pending(&dc->delay_timer) || expires < dc->delay_timer.expires)
63 mod_timer(&dc->delay_timer, expires);
65 mutex_unlock(&dc->timer_lock);
68 static void flush_bios(struct bio *bio)
75 submit_bio_noacct(bio);
80 static struct bio *flush_delayed_bios(struct delay_c *dc, int flush_all)
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 = { };
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--;
100 next_expires = delayed->expires;
102 next_expires = min(next_expires, delayed->expires);
104 mutex_unlock(&delayed_bios_lock);
107 queue_timeout(dc, next_expires);
109 return bio_list_get(&flush_bios);
112 static void flush_expired_bios(struct work_struct *work)
116 dc = container_of(work, struct delay_c, flush_expired_bios);
117 flush_bios(flush_delayed_bios(dc, 0));
120 static void delay_dtr(struct dm_target *ti)
122 struct delay_c *dc = ti->private;
125 destroy_workqueue(dc->kdelayd_wq);
128 dm_put_device(ti, dc->read.dev);
130 dm_put_device(ti, dc->write.dev);
132 dm_put_device(ti, dc->flush.dev);
134 mutex_destroy(&dc->timer_lock);
139 static int delay_class_ctr(struct dm_target *ti, struct delay_class *c, char **argv)
142 unsigned long long tmpll;
145 if (sscanf(argv[1], "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
146 ti->error = "Invalid device sector";
151 if (sscanf(argv[2], "%u%c", &c->delay, &dummy) != 1) {
152 ti->error = "Invalid delay";
156 ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &c->dev);
158 ti->error = "Device lookup failed";
166 * Mapping parameters:
167 * <device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
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.
173 static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv)
178 if (argc != 3 && argc != 6 && argc != 9) {
179 ti->error = "Requires exactly 3, 6 or 9 arguments";
183 dc = kzalloc(sizeof(*dc), GFP_KERNEL);
185 ti->error = "Cannot allocate context";
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);
197 ret = delay_class_ctr(ti, &dc->read, argv);
202 ret = delay_class_ctr(ti, &dc->write, argv);
205 ret = delay_class_ctr(ti, &dc->flush, argv);
211 ret = delay_class_ctr(ti, &dc->write, argv + 3);
215 ret = delay_class_ctr(ti, &dc->flush, argv + 3);
221 ret = delay_class_ctr(ti, &dc->flush, argv + 6);
226 dc->kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0);
227 if (!dc->kdelayd_wq) {
229 DMERR("Couldn't start kdelayd");
233 ti->num_flush_bios = 1;
234 ti->num_discard_bios = 1;
235 ti->per_io_data_size = sizeof(struct dm_delay_info);
243 static int delay_bio(struct delay_c *dc, struct delay_class *c, struct bio *bio)
245 struct dm_delay_info *delayed;
246 unsigned long expires = 0;
248 if (!c->delay || !atomic_read(&dc->may_delay))
249 return DM_MAPIO_REMAPPED;
251 delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info));
253 delayed->context = dc;
254 delayed->expires = expires = jiffies + msecs_to_jiffies(c->delay);
256 mutex_lock(&delayed_bios_lock);
258 list_add_tail(&delayed->list, &dc->delayed_bios);
259 mutex_unlock(&delayed_bios_lock);
261 queue_timeout(dc, expires);
263 return DM_MAPIO_SUBMITTED;
266 static void delay_presuspend(struct dm_target *ti)
268 struct delay_c *dc = ti->private;
270 atomic_set(&dc->may_delay, 0);
271 del_timer_sync(&dc->delay_timer);
272 flush_bios(flush_delayed_bios(dc, 1));
275 static void delay_resume(struct dm_target *ti)
277 struct delay_c *dc = ti->private;
279 atomic_set(&dc->may_delay, 1);
282 static int delay_map(struct dm_target *ti, struct bio *bio)
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));
288 if (bio_data_dir(bio) == WRITE) {
289 if (unlikely(bio->bi_opf & REQ_PREFLUSH))
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);
301 return delay_bio(dc, c, bio);
304 #define DMEMIT_DELAY_CLASS(c) \
305 DMEMIT("%s %llu %u", (c)->dev->name, (unsigned long long)(c)->start, (c)->delay)
307 static void delay_status(struct dm_target *ti, status_type_t type,
308 unsigned status_flags, char *result, unsigned maxlen)
310 struct delay_c *dc = ti->private;
314 case STATUSTYPE_INFO:
315 DMEMIT("%u %u %u", dc->read.ops, dc->write.ops, dc->flush.ops);
318 case STATUSTYPE_TABLE:
319 DMEMIT_DELAY_CLASS(&dc->read);
322 DMEMIT_DELAY_CLASS(&dc->write);
326 DMEMIT_DELAY_CLASS(&dc->flush);
332 static int delay_iterate_devices(struct dm_target *ti,
333 iterate_devices_callout_fn fn, void *data)
335 struct delay_c *dc = ti->private;
338 ret = fn(ti, dc->read.dev, dc->read.start, ti->len, data);
341 ret = fn(ti, dc->write.dev, dc->write.start, ti->len, data);
344 ret = fn(ti, dc->flush.dev, dc->flush.start, ti->len, data);
352 static struct target_type delay_target = {
354 .version = {1, 2, 1},
355 .features = DM_TARGET_PASSES_INTEGRITY,
356 .module = THIS_MODULE,
360 .presuspend = delay_presuspend,
361 .resume = delay_resume,
362 .status = delay_status,
363 .iterate_devices = delay_iterate_devices,
366 static int __init dm_delay_init(void)
370 r = dm_register_target(&delay_target);
372 DMERR("register failed %d", r);
382 static void __exit dm_delay_exit(void)
384 dm_unregister_target(&delay_target);
388 module_init(dm_delay_init);
389 module_exit(dm_delay_exit);
391 MODULE_DESCRIPTION(DM_NAME " delay target");
392 MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
393 MODULE_LICENSE("GPL");