[linux-2.6-block.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 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 workqueue_struct *kdelayd_wq;
static struct kmem_cache *delayed_cache;

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

	queue_work(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;

	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", &tmpll) != 1) {
		ti->error = "Invalid device sector";
		goto bad;
	}
	dc->start_read = tmpll;

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

	if (dm_get_device(ti, argv[0], dc->start_read, ti->len,
			  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", &tmpll) != 1) {
		ti->error = "Invalid write device sector";
		goto bad_dev_read;
	}
	dc->start_write = tmpll;

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

	if (dm_get_device(ti, argv[3], dc->start_write, ti->len,
			  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;
	}

	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->private = dc;
	return 0;

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;

	flush_workqueue(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,
		     union map_info *map_context)
{
	struct delay_c *dc = ti->private;

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

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

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

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

static int delay_status(struct dm_target *ti, status_type_t type,
			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;
	}

	return 0;
}

static struct target_type delay_target = {
	.name	     = "delay",
	.version     = {1, 0, 2},
	.module      = THIS_MODULE,
	.ctr	     = delay_ctr,
	.dtr	     = delay_dtr,
	.map	     = delay_map,
	.presuspend  = delay_presuspend,
	.resume	     = delay_resume,
	.status	     = delay_status,
};

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

	kdelayd_wq = create_workqueue("kdelayd");
	if (!kdelayd_wq) {
		DMERR("Couldn't start kdelayd");
		goto bad_queue;
	}

	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:
	destroy_workqueue(kdelayd_wq);
bad_queue:
	return r;
}

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

/* 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;
26b9f228 HM	23	struct work_struct flush_expired_bios;
	24	struct list_head delayed_bios;
	25	atomic_t may_delay;
	26	mempool_t *delayed_pool;
	27
	28	struct dm_dev *dev_read;
	29	sector_t start_read;
	30	unsigned read_delay;
	31	unsigned reads;
	32
	33	struct dm_dev *dev_write;
	34	sector_t start_write;
	35	unsigned write_delay;
	36	unsigned writes;
	37	};
	38
028867ac	39	struct dm_delay_info {
26b9f228 HM	40	struct delay_c *context;
	41	struct list_head list;
	42	struct bio *bio;
	43	unsigned long expires;
	44	};
	45
	46	static DEFINE_MUTEX(delayed_bios_lock);
	47
	48	static struct workqueue_struct *kdelayd_wq;
	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
	55	queue_work(kdelayd_wq, &dc->flush_expired_bios);
	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;
	134
	135	if (argc != 3 && argc != 6) {
	136	ti->error = "requires exactly 3 or 6 arguments";
	137	return -EINVAL;
	138	}
	139
	140	dc = kmalloc(sizeof(*dc), GFP_KERNEL);
	141	if (!dc) {
	142	ti->error = "Cannot allocate context";
	143	return -ENOMEM;
	144	}
	145
	146	dc->reads = dc->writes = 0;
	147
	148	if (sscanf(argv[1], "%llu", &tmpll) != 1) {
	149	ti->error = "Invalid device sector";
150	goto bad;
151	}
152	dc->start_read = tmpll;
153
154	if (sscanf(argv[2], "%u", &dc->read_delay) != 1) {
155	ti->error = "Invalid delay";
156	goto bad;
157	}
158
159	if (dm_get_device(ti, argv[0], dc->start_read, ti->len,
160	dm_table_get_mode(ti->table), &dc->dev_read)) {
161	ti->error = "Device lookup failed";
162	goto bad;
163	}
164
2e64a0f9 DM	165	dc->dev_write = NULL;
2e64a0f9 DM	166	if (argc == 3)
26b9f228	167	goto out;
26b9f228 HM	168
	169	if (sscanf(argv[4], "%llu", &tmpll) != 1) {
	170	ti->error = "Invalid write device sector";
2e64a0f9	171	goto bad_dev_read;
26b9f228 HM	172	}
	173	dc->start_write = tmpll;
	174
	175	if (sscanf(argv[5], "%u", &dc->write_delay) != 1) {
	176	ti->error = "Invalid write delay";
2e64a0f9	177	goto bad_dev_read;
26b9f228 HM	178	}
	179
	180	if (dm_get_device(ti, argv[3], dc->start_write, ti->len,
	181	dm_table_get_mode(ti->table), &dc->dev_write)) {
	182	ti->error = "Write device lookup failed";
2e64a0f9	183	goto bad_dev_read;
26b9f228 HM	184	}
	185
	186	out:
	187	dc->delayed_pool = mempool_create_slab_pool(128, delayed_cache);
	188	if (!dc->delayed_pool) {
	189	DMERR("Couldn't create delayed bio pool.");
2e64a0f9	190	goto bad_dev_write;
26b9f228 HM	191	}
26b9f228 HM	192
ac818646	193	setup_timer(&dc->delay_timer, handle_delayed_timer, (unsigned long)dc);
26b9f228 HM	194
	195	INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
	196	INIT_LIST_HEAD(&dc->delayed_bios);
ac818646	197	mutex_init(&dc->timer_lock);
26b9f228 HM	198	atomic_set(&dc->may_delay, 1);
	199
	200	ti->private = dc;
	201	return 0;
	202
2e64a0f9 DM	203	bad_dev_write:
	204	if (dc->dev_write)
	205	dm_put_device(ti, dc->dev_write);
	206	bad_dev_read:
	207	dm_put_device(ti, dc->dev_read);
26b9f228 HM	208	bad:
	209	kfree(dc);
	210	return -EINVAL;
	211	}
	212
	213	static void delay_dtr(struct dm_target *ti)
	214	{
	215	struct delay_c *dc = ti->private;
	216
	217	flush_workqueue(kdelayd_wq);
	218
	219	dm_put_device(ti, dc->dev_read);
	220
	221	if (dc->dev_write)
	222	dm_put_device(ti, dc->dev_write);
	223
	224	mempool_destroy(dc->delayed_pool);
	225	kfree(dc);
	226	}
	227
	228	static int delay_bio(struct delay_c dc, int delay, struct bio bio)
	229	{
028867ac	230	struct dm_delay_info *delayed;
26b9f228 HM	231	unsigned long expires = 0;
	232
	233	if (!delay \|\| !atomic_read(&dc->may_delay))
	234	return 1;
	235
	236	delayed = mempool_alloc(dc->delayed_pool, GFP_NOIO);
	237
	238	delayed->context = dc;
	239	delayed->bio = bio;
	240	delayed->expires = expires = jiffies + (delay * HZ / 1000);
	241
	242	mutex_lock(&delayed_bios_lock);
	243
	244	if (bio_data_dir(bio) == WRITE)
	245	dc->writes++;
	246	else
	247	dc->reads++;
	248
	249	list_add_tail(&delayed->list, &dc->delayed_bios);
	250
	251	mutex_unlock(&delayed_bios_lock);
	252
	253	queue_timeout(dc, expires);
	254
	255	return 0;
	256	}
	257
	258	static void delay_presuspend(struct dm_target *ti)
	259	{
	260	struct delay_c *dc = ti->private;
	261
	262	atomic_set(&dc->may_delay, 0);
	263	del_timer_sync(&dc->delay_timer);
	264	flush_bios(flush_delayed_bios(dc, 1));
	265	}
	266
	267	static void delay_resume(struct dm_target *ti)
	268	{
	269	struct delay_c *dc = ti->private;
	270
	271	atomic_set(&dc->may_delay, 1);
	272	}
	273
	274	static int delay_map(struct dm_target ti, struct bio bio,
	275	union map_info *map_context)
	276	{
	277	struct delay_c *dc = ti->private;
	278
	279	if ((bio_data_dir(bio) == WRITE) && (dc->dev_write)) {
	280	bio->bi_bdev = dc->dev_write->bdev;
	281	bio->bi_sector = dc->start_write +
	282	(bio->bi_sector - ti->begin);
	283
	284	return delay_bio(dc, dc->write_delay, bio);
	285	}
	286
	287	bio->bi_bdev = dc->dev_read->bdev;
	288	bio->bi_sector = dc->start_read +
	289	(bio->bi_sector - ti->begin);
	290
	291	return delay_bio(dc, dc->read_delay, bio);
	292	}
	293
	294	static int delay_status(struct dm_target *ti, status_type_t type,
295	char *result, unsigned maxlen)
296	{
297	struct delay_c *dc = ti->private;
298	int sz = 0;
299
300	switch (type) {
301	case STATUSTYPE_INFO:
302	DMEMIT("%u %u", dc->reads, dc->writes);
303	break;
304
305	case STATUSTYPE_TABLE:
306	DMEMIT("%s %llu %u", dc->dev_read->name,
307	(unsigned long long) dc->start_read,
308	dc->read_delay);
309	if (dc->dev_write)
79662d1e	310	DMEMIT(" %s %llu %u", dc->dev_write->name,
26b9f228 HM	311	(unsigned long long) dc->start_write,
	312	dc->write_delay);
	313	break;
	314	}
	315
	316	return 0;
	317	}
	318
	319	static struct target_type delay_target = {
	320	.name = "delay",
	321	.version = {1, 0, 2},
	322	.module = THIS_MODULE,
	323	.ctr = delay_ctr,
	324	.dtr = delay_dtr,
	325	.map = delay_map,
	326	.presuspend = delay_presuspend,
	327	.resume = delay_resume,
	328	.status = delay_status,
	329	};
	330
	331	static int __init dm_delay_init(void)
	332	{
	333	int r = -ENOMEM;
	334
	335	kdelayd_wq = create_workqueue("kdelayd");
	336	if (!kdelayd_wq) {
	337	DMERR("Couldn't start kdelayd");
	338	goto bad_queue;
	339	}
	340
028867ac	341	delayed_cache = KMEM_CACHE(dm_delay_info, 0);
26b9f228 HM	342	if (!delayed_cache) {
	343	DMERR("Couldn't create delayed bio cache.");
	344	goto bad_memcache;
	345	}
	346
	347	r = dm_register_target(&delay_target);
	348	if (r < 0) {
	349	DMERR("register failed %d", r);
	350	goto bad_register;
	351	}
	352
	353	return 0;
	354
	355	bad_register:
	356	kmem_cache_destroy(delayed_cache);
	357	bad_memcache:
	358	destroy_workqueue(kdelayd_wq);
	359	bad_queue:
	360	return r;
	361	}
	362
	363	static void __exit dm_delay_exit(void)
	364	{
10d3bd09	365	dm_unregister_target(&delay_target);
26b9f228 HM	366	kmem_cache_destroy(delayed_cache);
	367	destroy_workqueue(kdelayd_wq);
	368	}
	369
	370	/* Module hooks */
	371	module_init(dm_delay_init);
	372	module_exit(dm_delay_exit);
	373
	374	MODULE_DESCRIPTION(DM_NAME " delay target");
	375	MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
	376	MODULE_LICENSE("GPL");