[deliverable/linux.git] / drivers / md / dm-delay.c

/*
 * Copyright (C) 2005-2007 Red Hat GmbH
 *
 * A target that delays reads and/or writes and can send
 * them to different devices.
 *
 * This file is released under the GPL.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/slab.h>

#include <linux/device-mapper.h>

#define DM_MSG_PREFIX "delay"

struct delay_c {
	struct timer_list delay_timer;
	struct mutex timer_lock;
	struct workqueue_struct *kdelayd_wq;
	struct work_struct flush_expired_bios;
	struct list_head delayed_bios;
	atomic_t may_delay;
	mempool_t *delayed_pool;

	struct dm_dev *dev_read;
	sector_t start_read;
	unsigned read_delay;
	unsigned reads;

	struct dm_dev *dev_write;
	sector_t start_write;
	unsigned write_delay;
	unsigned writes;
};

struct dm_delay_info {
	struct delay_c *context;
	struct list_head list;
	struct bio *bio;
	unsigned long expires;
};

static DEFINE_MUTEX(delayed_bios_lock);

static struct kmem_cache *delayed_cache;

static void handle_delayed_timer(unsigned long data)
{
	struct delay_c *dc = (struct delay_c *)data;

	queue_work(dc->kdelayd_wq, &dc->flush_expired_bios);
}

static void queue_timeout(struct delay_c *dc, unsigned long expires)
{
	mutex_lock(&dc->timer_lock);

	if (!timer_pending(&dc->delay_timer) || expires < dc->delay_timer.expires)
		mod_timer(&dc->delay_timer, expires);

	mutex_unlock(&dc->timer_lock);
}

static void flush_bios(struct bio *bio)
{
	struct bio *n;

	while (bio) {
		n = bio->bi_next;
		bio->bi_next = NULL;
		generic_make_request(bio);
		bio = n;
	}
}

static struct bio *flush_delayed_bios(struct delay_c *dc, int flush_all)
{
	struct dm_delay_info *delayed, *next;
	unsigned long next_expires = 0;
	int start_timer = 0;
	struct bio_list flush_bios = { };

	mutex_lock(&delayed_bios_lock);
	list_for_each_entry_safe(delayed, next, &dc->delayed_bios, list) {
		if (flush_all || time_after_eq(jiffies, delayed->expires)) {
			list_del(&delayed->list);
			bio_list_add(&flush_bios, delayed->bio);
			if ((bio_data_dir(delayed->bio) == WRITE))
				delayed->context->writes--;
			else
				delayed->context->reads--;
			mempool_free(delayed, dc->delayed_pool);
			continue;
		}

		if (!start_timer) {
			start_timer = 1;
			next_expires = delayed->expires;
		} else
			next_expires = min(next_expires, delayed->expires);
	}

	mutex_unlock(&delayed_bios_lock);

	if (start_timer)
		queue_timeout(dc, next_expires);

	return bio_list_get(&flush_bios);
}

static void flush_expired_bios(struct work_struct *work)
{
	struct delay_c *dc;

	dc = container_of(work, struct delay_c, flush_expired_bios);
	flush_bios(flush_delayed_bios(dc, 0));
}

/*
 * Mapping parameters:
 *    <device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
 *
 * With separate write parameters, the first set is only used for reads.
 * Delays are specified in milliseconds.
 */
static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
	struct delay_c *dc;
	unsigned long long tmpll;
	char dummy;

	if (argc != 3 && argc != 6) {
		ti->error = "requires exactly 3 or 6 arguments";
		return -EINVAL;
	}

	dc = kmalloc(sizeof(*dc), GFP_KERNEL);
	if (!dc) {
		ti->error = "Cannot allocate context";
		return -ENOMEM;
	}

	dc->reads = dc->writes = 0;

	if (sscanf(argv[1], "%llu%c", &tmpll, &dummy) != 1) {
		ti->error = "Invalid device sector";
		goto bad;
	}
	dc->start_read = tmpll;

	if (sscanf(argv[2], "%u%c", &dc->read_delay, &dummy) != 1) {
		ti->error = "Invalid delay";
		goto bad;
	}

	if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
			  &dc->dev_read)) {
		ti->error = "Device lookup failed";
		goto bad;
	}

	dc->dev_write = NULL;
	if (argc == 3)
		goto out;

	if (sscanf(argv[4], "%llu%c", &tmpll, &dummy) != 1) {
		ti->error = "Invalid write device sector";
		goto bad_dev_read;
	}
	dc->start_write = tmpll;

	if (sscanf(argv[5], "%u%c", &dc->write_delay, &dummy) != 1) {
		ti->error = "Invalid write delay";
		goto bad_dev_read;
	}

	if (dm_get_device(ti, argv[3], dm_table_get_mode(ti->table),
			  &dc->dev_write)) {
		ti->error = "Write device lookup failed";
		goto bad_dev_read;
	}

out:
	dc->delayed_pool = mempool_create_slab_pool(128, delayed_cache);
	if (!dc->delayed_pool) {
		DMERR("Couldn't create delayed bio pool.");
		goto bad_dev_write;
	}

	dc->kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0);
	if (!dc->kdelayd_wq) {
		DMERR("Couldn't start kdelayd");
		goto bad_queue;
	}

	setup_timer(&dc->delay_timer, handle_delayed_timer, (unsigned long)dc);

	INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
	INIT_LIST_HEAD(&dc->delayed_bios);
	mutex_init(&dc->timer_lock);
	atomic_set(&dc->may_delay, 1);

	ti->num_flush_bios = 1;
	ti->num_discard_bios = 1;
	ti->private = dc;
	return 0;

bad_queue:
	mempool_destroy(dc->delayed_pool);
bad_dev_write:
	if (dc->dev_write)
		dm_put_device(ti, dc->dev_write);
bad_dev_read:
	dm_put_device(ti, dc->dev_read);
bad:
	kfree(dc);
	return -EINVAL;
}

static void delay_dtr(struct dm_target *ti)
{
	struct delay_c *dc = ti->private;

	destroy_workqueue(dc->kdelayd_wq);

	dm_put_device(ti, dc->dev_read);

	if (dc->dev_write)
		dm_put_device(ti, dc->dev_write);

	mempool_destroy(dc->delayed_pool);
	kfree(dc);
}

static int delay_bio(struct delay_c *dc, int delay, struct bio *bio)
{
	struct dm_delay_info *delayed;
	unsigned long expires = 0;

	if (!delay || !atomic_read(&dc->may_delay))
		return 1;

	delayed = mempool_alloc(dc->delayed_pool, GFP_NOIO);

	delayed->context = dc;
	delayed->bio = bio;
	delayed->expires = expires = jiffies + (delay * HZ / 1000);

	mutex_lock(&delayed_bios_lock);

	if (bio_data_dir(bio) == WRITE)
		dc->writes++;
	else
		dc->reads++;

	list_add_tail(&delayed->list, &dc->delayed_bios);

	mutex_unlock(&delayed_bios_lock);

	queue_timeout(dc, expires);

	return 0;
}

static void delay_presuspend(struct dm_target *ti)
{
	struct delay_c *dc = ti->private;

	atomic_set(&dc->may_delay, 0);
	del_timer_sync(&dc->delay_timer);
	flush_bios(flush_delayed_bios(dc, 1));
}

static void delay_resume(struct dm_target *ti)
{
	struct delay_c *dc = ti->private;

	atomic_set(&dc->may_delay, 1);
}

static int delay_map(struct dm_target *ti, struct bio *bio)
{
	struct delay_c *dc = ti->private;

	if ((bio_data_dir(bio) == WRITE) && (dc->dev_write)) {
		bio->bi_bdev = dc->dev_write->bdev;
		if (bio_sectors(bio))
			bio->bi_sector = dc->start_write +
					 dm_target_offset(ti, bio->bi_sector);

		return delay_bio(dc, dc->write_delay, bio);
	}

	bio->bi_bdev = dc->dev_read->bdev;
	bio->bi_sector = dc->start_read + dm_target_offset(ti, bio->bi_sector);

	return delay_bio(dc, dc->read_delay, bio);
}

static void delay_status(struct dm_target *ti, status_type_t type,
			 unsigned status_flags, char *result, unsigned maxlen)
{
	struct delay_c *dc = ti->private;
	int sz = 0;

	switch (type) {
	case STATUSTYPE_INFO:
		DMEMIT("%u %u", dc->reads, dc->writes);
		break;

	case STATUSTYPE_TABLE:
		DMEMIT("%s %llu %u", dc->dev_read->name,
		       (unsigned long long) dc->start_read,
		       dc->read_delay);
		if (dc->dev_write)
			DMEMIT(" %s %llu %u", dc->dev_write->name,
			       (unsigned long long) dc->start_write,
			       dc->write_delay);
		break;
	}
}

static int delay_iterate_devices(struct dm_target *ti,
				 iterate_devices_callout_fn fn, void *data)
{
	struct delay_c *dc = ti->private;
	int ret = 0;

	ret = fn(ti, dc->dev_read, dc->start_read, ti->len, data);
	if (ret)
		goto out;

	if (dc->dev_write)
		ret = fn(ti, dc->dev_write, dc->start_write, ti->len, data);

out:
	return ret;
}

static struct target_type delay_target = {
	.name	     = "delay",
	.version     = {1, 2, 1},
	.module      = THIS_MODULE,
	.ctr	     = delay_ctr,
	.dtr	     = delay_dtr,
	.map	     = delay_map,
	.presuspend  = delay_presuspend,
	.resume	     = delay_resume,
	.status	     = delay_status,
	.iterate_devices = delay_iterate_devices,
};

static int __init dm_delay_init(void)
{
	int r = -ENOMEM;

	delayed_cache = KMEM_CACHE(dm_delay_info, 0);
	if (!delayed_cache) {
		DMERR("Couldn't create delayed bio cache.");
		goto bad_memcache;
	}

	r = dm_register_target(&delay_target);
	if (r < 0) {
		DMERR("register failed %d", r);
		goto bad_register;
	}

	return 0;

bad_register:
	kmem_cache_destroy(delayed_cache);
bad_memcache:
	return r;
}

static void __exit dm_delay_exit(void)
{
	dm_unregister_target(&delay_target);
	kmem_cache_destroy(delayed_cache);
}

/* Module hooks */
module_init(dm_delay_init);
module_exit(dm_delay_exit);

MODULE_DESCRIPTION(DM_NAME " delay target");
MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
MODULE_LICENSE("GPL");
Commit	Line	Data
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
586e80e6 MP	16	#include <linux/device-mapper.h>
586e80e6 MP	17
26b9f228 HM	18	#define DM_MSG_PREFIX "delay"
	19
	20	struct delay_c {
	21	struct timer_list delay_timer;
ac818646	22	struct mutex timer_lock;
718822c1	23	struct workqueue_struct *kdelayd_wq;
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
26b9f228 HM	49	static struct kmem_cache *delayed_cache;
	50
	51	static void handle_delayed_timer(unsigned long data)
	52	{
	53	struct delay_c dc = (struct delay_c )data;
	54
718822c1	55	queue_work(dc->kdelayd_wq, &dc->flush_expired_bios);
26b9f228 HM	56	}
	57
	58	static void queue_timeout(struct delay_c *dc, unsigned long expires)
	59	{
ac818646	60	mutex_lock(&dc->timer_lock);
26b9f228 HM	61
	62	if (!timer_pending(&dc->delay_timer) \|\| expires < dc->delay_timer.expires)
	63	mod_timer(&dc->delay_timer, expires);
	64
ac818646	65	mutex_unlock(&dc->timer_lock);
26b9f228 HM	66	}
	67
	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	generic_make_request(bio);
	76	bio = n;
	77	}
	78	}
	79
	80	static struct bio flush_delayed_bios(struct delay_c dc, int flush_all)
	81	{
028867ac	82	struct dm_delay_info delayed, next;
26b9f228 HM	83	unsigned long next_expires = 0;
26b9f228 HM	84	int start_timer = 0;
051814c6	85	struct bio_list flush_bios = { };
26b9f228 HM	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	list_del(&delayed->list);
	91	bio_list_add(&flush_bios, delayed->bio);
	92	if ((bio_data_dir(delayed->bio) == WRITE))
	93	delayed->context->writes--;
	94	else
	95	delayed->context->reads--;
	96	mempool_free(delayed, dc->delayed_pool);
	97	continue;
	98	}
	99
	100	if (!start_timer) {
	101	start_timer = 1;
	102	next_expires = delayed->expires;
	103	} else
	104	next_expires = min(next_expires, delayed->expires);
	105	}
	106
	107	mutex_unlock(&delayed_bios_lock);
	108
	109	if (start_timer)
	110	queue_timeout(dc, next_expires);
	111
	112	return bio_list_get(&flush_bios);
	113	}
	114
	115	static void flush_expired_bios(struct work_struct *work)
	116	{
	117	struct delay_c *dc;
	118
	119	dc = container_of(work, struct delay_c, flush_expired_bios);
	120	flush_bios(flush_delayed_bios(dc, 0));
	121	}
	122
	123	/*
	124	* Mapping parameters:
	125	* <device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
	126	*
	127	* With separate write parameters, the first set is only used for reads.
	128	* Delays are specified in milliseconds.
	129	*/
	130	static int delay_ctr(struct dm_target ti, unsigned int argc, char *argv)
	131	{
	132	struct delay_c *dc;
	133	unsigned long long tmpll;
31998ef1	134	char dummy;
26b9f228 HM	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
31998ef1	149	if (sscanf(argv[1], "%llu%c", &tmpll, &dummy) != 1) {
26b9f228 HM	150	ti->error = "Invalid device sector";
	151	goto bad;
	152	}
	153	dc->start_read = tmpll;
	154
31998ef1	155	if (sscanf(argv[2], "%u%c", &dc->read_delay, &dummy) != 1) {
26b9f228 HM	156	ti->error = "Invalid delay";
	157	goto bad;
	158	}
	159
8215d6ec NK	160	if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
8215d6ec NK	161	&dc->dev_read)) {
26b9f228 HM	162	ti->error = "Device lookup failed";
	163	goto bad;
	164	}
	165
2e64a0f9 DM	166	dc->dev_write = NULL;
2e64a0f9 DM	167	if (argc == 3)
26b9f228	168	goto out;
26b9f228	169
31998ef1	170	if (sscanf(argv[4], "%llu%c", &tmpll, &dummy) != 1) {
26b9f228	171	ti->error = "Invalid write device sector";
2e64a0f9	172	goto bad_dev_read;
26b9f228 HM	173	}
	174	dc->start_write = tmpll;
	175
31998ef1	176	if (sscanf(argv[5], "%u%c", &dc->write_delay, &dummy) != 1) {
26b9f228	177	ti->error = "Invalid write delay";
2e64a0f9	178	goto bad_dev_read;
26b9f228 HM	179	}
26b9f228 HM	180
8215d6ec NK	181	if (dm_get_device(ti, argv[3], dm_table_get_mode(ti->table),
8215d6ec NK	182	&dc->dev_write)) {
26b9f228	183	ti->error = "Write device lookup failed";
2e64a0f9	184	goto bad_dev_read;
26b9f228 HM	185	}
	186
	187	out:
	188	dc->delayed_pool = mempool_create_slab_pool(128, delayed_cache);
	189	if (!dc->delayed_pool) {
	190	DMERR("Couldn't create delayed bio pool.");
2e64a0f9	191	goto bad_dev_write;
26b9f228 HM	192	}
26b9f228 HM	193
718822c1 MP	194	dc->kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0);
	195	if (!dc->kdelayd_wq) {
	196	DMERR("Couldn't start kdelayd");
	197	goto bad_queue;
	198	}
	199
ac818646	200	setup_timer(&dc->delay_timer, handle_delayed_timer, (unsigned long)dc);
26b9f228 HM	201
	202	INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
	203	INIT_LIST_HEAD(&dc->delayed_bios);
ac818646	204	mutex_init(&dc->timer_lock);
26b9f228 HM	205	atomic_set(&dc->may_delay, 1);
26b9f228 HM	206
55a62eef AK	207	ti->num_flush_bios = 1;
55a62eef AK	208	ti->num_discard_bios = 1;
26b9f228 HM	209	ti->private = dc;
	210	return 0;
	211
718822c1 MP	212	bad_queue:
718822c1 MP	213	mempool_destroy(dc->delayed_pool);
2e64a0f9 DM	214	bad_dev_write:
	215	if (dc->dev_write)
	216	dm_put_device(ti, dc->dev_write);
	217	bad_dev_read:
	218	dm_put_device(ti, dc->dev_read);
26b9f228 HM	219	bad:
	220	kfree(dc);
	221	return -EINVAL;
	222	}
	223
	224	static void delay_dtr(struct dm_target *ti)
	225	{
	226	struct delay_c *dc = ti->private;
	227
718822c1	228	destroy_workqueue(dc->kdelayd_wq);
26b9f228 HM	229
	230	dm_put_device(ti, dc->dev_read);
	231
	232	if (dc->dev_write)
	233	dm_put_device(ti, dc->dev_write);
	234
	235	mempool_destroy(dc->delayed_pool);
	236	kfree(dc);
	237	}
	238
	239	static int delay_bio(struct delay_c dc, int delay, struct bio bio)
	240	{
028867ac	241	struct dm_delay_info *delayed;
26b9f228 HM	242	unsigned long expires = 0;
	243
	244	if (!delay \|\| !atomic_read(&dc->may_delay))
	245	return 1;
	246
	247	delayed = mempool_alloc(dc->delayed_pool, GFP_NOIO);
	248
	249	delayed->context = dc;
	250	delayed->bio = bio;
	251	delayed->expires = expires = jiffies + (delay * HZ / 1000);
	252
	253	mutex_lock(&delayed_bios_lock);
	254
	255	if (bio_data_dir(bio) == WRITE)
	256	dc->writes++;
	257	else
	258	dc->reads++;
	259
	260	list_add_tail(&delayed->list, &dc->delayed_bios);
	261
	262	mutex_unlock(&delayed_bios_lock);
	263
	264	queue_timeout(dc, expires);
	265
	266	return 0;
	267	}
	268
	269	static void delay_presuspend(struct dm_target *ti)
	270	{
	271	struct delay_c *dc = ti->private;
	272
	273	atomic_set(&dc->may_delay, 0);
	274	del_timer_sync(&dc->delay_timer);
	275	flush_bios(flush_delayed_bios(dc, 1));
	276	}
	277
	278	static void delay_resume(struct dm_target *ti)
	279	{
	280	struct delay_c *dc = ti->private;
	281
	282	atomic_set(&dc->may_delay, 1);
	283	}
	284
7de3ee57	285	static int delay_map(struct dm_target ti, struct bio bio)
26b9f228 HM	286	{
	287	struct delay_c *dc = ti->private;
	288
	289	if ((bio_data_dir(bio) == WRITE) && (dc->dev_write)) {
	290	bio->bi_bdev = dc->dev_write->bdev;
c927259e MP	291	if (bio_sectors(bio))
c927259e MP	292	bio->bi_sector = dc->start_write +
b441a262	293	dm_target_offset(ti, bio->bi_sector);
26b9f228 HM	294
	295	return delay_bio(dc, dc->write_delay, bio);
	296	}
	297
	298	bio->bi_bdev = dc->dev_read->bdev;
b441a262	299	bio->bi_sector = dc->start_read + dm_target_offset(ti, bio->bi_sector);
26b9f228 HM	300
	301	return delay_bio(dc, dc->read_delay, bio);
	302	}
	303
fd7c092e MP	304	static void delay_status(struct dm_target *ti, status_type_t type,
fd7c092e MP	305	unsigned status_flags, char *result, unsigned maxlen)
26b9f228 HM	306	{
	307	struct delay_c *dc = ti->private;
	308	int sz = 0;
	309
	310	switch (type) {
	311	case STATUSTYPE_INFO:
	312	DMEMIT("%u %u", dc->reads, dc->writes);
	313	break;
	314
	315	case STATUSTYPE_TABLE:
	316	DMEMIT("%s %llu %u", dc->dev_read->name,
	317	(unsigned long long) dc->start_read,
	318	dc->read_delay);
	319	if (dc->dev_write)
79662d1e	320	DMEMIT(" %s %llu %u", dc->dev_write->name,
26b9f228 HM	321	(unsigned long long) dc->start_write,
	322	dc->write_delay);
	323	break;
	324	}
26b9f228 HM	325	}
26b9f228 HM	326
af4874e0 MS	327	static int delay_iterate_devices(struct dm_target *ti,
	328	iterate_devices_callout_fn fn, void *data)
	329	{
	330	struct delay_c *dc = ti->private;
	331	int ret = 0;
	332
5dea271b	333	ret = fn(ti, dc->dev_read, dc->start_read, ti->len, data);
af4874e0 MS	334	if (ret)
	335	goto out;
	336
	337	if (dc->dev_write)
5dea271b	338	ret = fn(ti, dc->dev_write, dc->start_write, ti->len, data);
af4874e0 MS	339
	340	out:
	341	return ret;
	342	}
	343
26b9f228 HM	344	static struct target_type delay_target = {
26b9f228 HM	345	.name = "delay",
fd7c092e	346	.version = {1, 2, 1},
26b9f228 HM	347	.module = THIS_MODULE,
	348	.ctr = delay_ctr,
	349	.dtr = delay_dtr,
	350	.map = delay_map,
	351	.presuspend = delay_presuspend,
	352	.resume = delay_resume,
	353	.status = delay_status,
af4874e0	354	.iterate_devices = delay_iterate_devices,
26b9f228 HM	355	};
	356
	357	static int __init dm_delay_init(void)
	358	{
	359	int r = -ENOMEM;
	360
028867ac	361	delayed_cache = KMEM_CACHE(dm_delay_info, 0);
26b9f228 HM	362	if (!delayed_cache) {
	363	DMERR("Couldn't create delayed bio cache.");
	364	goto bad_memcache;
	365	}
	366
	367	r = dm_register_target(&delay_target);
	368	if (r < 0) {
	369	DMERR("register failed %d", r);
	370	goto bad_register;
	371	}
	372
	373	return 0;
	374
	375	bad_register:
	376	kmem_cache_destroy(delayed_cache);
	377	bad_memcache:
26b9f228 HM	378	return r;
	379	}
	380
	381	static void __exit dm_delay_exit(void)
	382	{
10d3bd09	383	dm_unregister_target(&delay_target);
26b9f228	384	kmem_cache_destroy(delayed_cache);
26b9f228 HM	385	}
	386
	387	/* Module hooks */
	388	module_init(dm_delay_init);
	389	module_exit(dm_delay_exit);
	390
	391	MODULE_DESCRIPTION(DM_NAME " delay target");
	392	MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
	393	MODULE_LICENSE("GPL");