[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>

#include "dm-bio-list.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	#include "dm-bio-list.h"
	19
	20	#define DM_MSG_PREFIX "delay"
	21
	22	struct delay_c {
	23	struct timer_list delay_timer;
ac818646	24	struct mutex timer_lock;
26b9f228 HM	25	struct work_struct flush_expired_bios;
	26	struct list_head delayed_bios;
	27	atomic_t may_delay;
	28	mempool_t *delayed_pool;
	29
	30	struct dm_dev *dev_read;
	31	sector_t start_read;
	32	unsigned read_delay;
	33	unsigned reads;
	34
	35	struct dm_dev *dev_write;
	36	sector_t start_write;
	37	unsigned write_delay;
	38	unsigned writes;
	39	};
	40
028867ac	41	struct dm_delay_info {
26b9f228 HM	42	struct delay_c *context;
	43	struct list_head list;
	44	struct bio *bio;
	45	unsigned long expires;
	46	};
	47
	48	static DEFINE_MUTEX(delayed_bios_lock);
	49
	50	static struct workqueue_struct *kdelayd_wq;
	51	static struct kmem_cache *delayed_cache;
	52
	53	static void handle_delayed_timer(unsigned long data)
	54	{
	55	struct delay_c dc = (struct delay_c )data;
	56
	57	queue_work(kdelayd_wq, &dc->flush_expired_bios);
	58	}
	59
	60	static void queue_timeout(struct delay_c *dc, unsigned long expires)
	61	{
ac818646	62	mutex_lock(&dc->timer_lock);
26b9f228 HM	63
	64	if (!timer_pending(&dc->delay_timer) \|\| expires < dc->delay_timer.expires)
	65	mod_timer(&dc->delay_timer, expires);
	66
ac818646	67	mutex_unlock(&dc->timer_lock);
26b9f228 HM	68	}
	69
	70	static 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	generic_make_request(bio);
	78	bio = n;
	79	}
	80	}
	81
	82	static struct bio flush_delayed_bios(struct delay_c dc, int flush_all)
	83	{
028867ac	84	struct dm_delay_info delayed, next;
26b9f228 HM	85	unsigned long next_expires = 0;
26b9f228 HM	86	int start_timer = 0;
051814c6	87	struct bio_list flush_bios = { };
26b9f228 HM	88
	89	mutex_lock(&delayed_bios_lock);
	90	list_for_each_entry_safe(delayed, next, &dc->delayed_bios, list) {
	91	if (flush_all \|\| time_after_eq(jiffies, delayed->expires)) {
	92	list_del(&delayed->list);
	93	bio_list_add(&flush_bios, delayed->bio);
	94	if ((bio_data_dir(delayed->bio) == WRITE))
	95	delayed->context->writes--;
	96	else
	97	delayed->context->reads--;
	98	mempool_free(delayed, dc->delayed_pool);
	99	continue;
	100	}
	101
	102	if (!start_timer) {
	103	start_timer = 1;
	104	next_expires = delayed->expires;
	105	} else
	106	next_expires = min(next_expires, delayed->expires);
	107	}
	108
	109	mutex_unlock(&delayed_bios_lock);
	110
	111	if (start_timer)
	112	queue_timeout(dc, next_expires);
	113
	114	return bio_list_get(&flush_bios);
	115	}
	116
	117	static void flush_expired_bios(struct work_struct *work)
	118	{
	119	struct delay_c *dc;
	120
	121	dc = container_of(work, struct delay_c, flush_expired_bios);
	122	flush_bios(flush_delayed_bios(dc, 0));
	123	}
	124
	125	/*
	126	* Mapping parameters:
	127	* <device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
	128	*
	129	* With separate write parameters, the first set is only used for reads.
	130	* Delays are specified in milliseconds.
	131	*/
	132	static int delay_ctr(struct dm_target ti, unsigned int argc, char *argv)
	133	{
	134	struct delay_c *dc;
	135	unsigned long long tmpll;
	136
	137	if (argc != 3 && argc != 6) {
	138	ti->error = "requires exactly 3 or 6 arguments";
	139	return -EINVAL;
	140	}
	141
	142	dc = kmalloc(sizeof(*dc), GFP_KERNEL);
	143	if (!dc) {
	144	ti->error = "Cannot allocate context";
	145	return -ENOMEM;
	146	}
	147
	148	dc->reads = dc->writes = 0;
	149
	150	if (sscanf(argv[1], "%llu", &tmpll) != 1) {
	151	ti->error = "Invalid device sector";
152	goto bad;
153	}
154	dc->start_read = tmpll;
155
156	if (sscanf(argv[2], "%u", &dc->read_delay) != 1) {
157	ti->error = "Invalid delay";
158	goto bad;
159	}
160
161	if (dm_get_device(ti, argv[0], dc->start_read, ti->len,
162	dm_table_get_mode(ti->table), &dc->dev_read)) {
163	ti->error = "Device lookup failed";
164	goto bad;
165	}
166
2e64a0f9 DM	167	dc->dev_write = NULL;
2e64a0f9 DM	168	if (argc == 3)
26b9f228	169	goto out;
26b9f228 HM	170
	171	if (sscanf(argv[4], "%llu", &tmpll) != 1) {
	172	ti->error = "Invalid write device sector";
2e64a0f9	173	goto bad_dev_read;
26b9f228 HM	174	}
	175	dc->start_write = tmpll;
	176
	177	if (sscanf(argv[5], "%u", &dc->write_delay) != 1) {
	178	ti->error = "Invalid write delay";
2e64a0f9	179	goto bad_dev_read;
26b9f228 HM	180	}
	181
	182	if (dm_get_device(ti, argv[3], dc->start_write, ti->len,
	183	dm_table_get_mode(ti->table), &dc->dev_write)) {
	184	ti->error = "Write device lookup failed";
2e64a0f9	185	goto bad_dev_read;
26b9f228 HM	186	}
	187
	188	out:
	189	dc->delayed_pool = mempool_create_slab_pool(128, delayed_cache);
	190	if (!dc->delayed_pool) {
	191	DMERR("Couldn't create delayed bio pool.");
2e64a0f9	192	goto bad_dev_write;
26b9f228 HM	193	}
26b9f228 HM	194
ac818646	195	setup_timer(&dc->delay_timer, handle_delayed_timer, (unsigned long)dc);
26b9f228 HM	196
	197	INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
	198	INIT_LIST_HEAD(&dc->delayed_bios);
ac818646	199	mutex_init(&dc->timer_lock);
26b9f228 HM	200	atomic_set(&dc->may_delay, 1);
	201
	202	ti->private = dc;
	203	return 0;
	204
2e64a0f9 DM	205	bad_dev_write:
	206	if (dc->dev_write)
	207	dm_put_device(ti, dc->dev_write);
	208	bad_dev_read:
	209	dm_put_device(ti, dc->dev_read);
26b9f228 HM	210	bad:
	211	kfree(dc);
	212	return -EINVAL;
	213	}
	214
	215	static void delay_dtr(struct dm_target *ti)
	216	{
	217	struct delay_c *dc = ti->private;
	218
	219	flush_workqueue(kdelayd_wq);
	220
	221	dm_put_device(ti, dc->dev_read);
	222
	223	if (dc->dev_write)
	224	dm_put_device(ti, dc->dev_write);
	225
	226	mempool_destroy(dc->delayed_pool);
	227	kfree(dc);
	228	}
	229
	230	static int delay_bio(struct delay_c dc, int delay, struct bio bio)
	231	{
028867ac	232	struct dm_delay_info *delayed;
26b9f228 HM	233	unsigned long expires = 0;
	234
	235	if (!delay \|\| !atomic_read(&dc->may_delay))
	236	return 1;
	237
	238	delayed = mempool_alloc(dc->delayed_pool, GFP_NOIO);
	239
	240	delayed->context = dc;
	241	delayed->bio = bio;
	242	delayed->expires = expires = jiffies + (delay * HZ / 1000);
	243
	244	mutex_lock(&delayed_bios_lock);
	245
	246	if (bio_data_dir(bio) == WRITE)
	247	dc->writes++;
	248	else
	249	dc->reads++;
	250
	251	list_add_tail(&delayed->list, &dc->delayed_bios);
	252
	253	mutex_unlock(&delayed_bios_lock);
	254
	255	queue_timeout(dc, expires);
	256
	257	return 0;
	258	}
	259
	260	static void delay_presuspend(struct dm_target *ti)
	261	{
	262	struct delay_c *dc = ti->private;
	263
	264	atomic_set(&dc->may_delay, 0);
	265	del_timer_sync(&dc->delay_timer);
	266	flush_bios(flush_delayed_bios(dc, 1));
	267	}
	268
	269	static void delay_resume(struct dm_target *ti)
	270	{
	271	struct delay_c *dc = ti->private;
	272
	273	atomic_set(&dc->may_delay, 1);
	274	}
	275
	276	static int delay_map(struct dm_target ti, struct bio bio,
	277	union map_info *map_context)
	278	{
	279	struct delay_c *dc = ti->private;
	280
	281	if ((bio_data_dir(bio) == WRITE) && (dc->dev_write)) {
	282	bio->bi_bdev = dc->dev_write->bdev;
	283	bio->bi_sector = dc->start_write +
	284	(bio->bi_sector - ti->begin);
	285
	286	return delay_bio(dc, dc->write_delay, bio);
	287	}
	288
	289	bio->bi_bdev = dc->dev_read->bdev;
	290	bio->bi_sector = dc->start_read +
	291	(bio->bi_sector - ti->begin);
	292
	293	return delay_bio(dc, dc->read_delay, bio);
	294	}
	295
	296	static int delay_status(struct dm_target *ti, status_type_t type,
297	char *result, unsigned maxlen)
298	{
299	struct delay_c *dc = ti->private;
300	int sz = 0;
301
302	switch (type) {
303	case STATUSTYPE_INFO:
304	DMEMIT("%u %u", dc->reads, dc->writes);
305	break;
306
307	case STATUSTYPE_TABLE:
308	DMEMIT("%s %llu %u", dc->dev_read->name,
309	(unsigned long long) dc->start_read,
310	dc->read_delay);
311	if (dc->dev_write)
79662d1e	312	DMEMIT(" %s %llu %u", dc->dev_write->name,
26b9f228 HM	313	(unsigned long long) dc->start_write,
	314	dc->write_delay);
	315	break;
	316	}
	317
	318	return 0;
	319	}
	320
	321	static struct target_type delay_target = {
	322	.name = "delay",
	323	.version = {1, 0, 2},
	324	.module = THIS_MODULE,
	325	.ctr = delay_ctr,
	326	.dtr = delay_dtr,
	327	.map = delay_map,
	328	.presuspend = delay_presuspend,
	329	.resume = delay_resume,
	330	.status = delay_status,
	331	};
	332
	333	static int __init dm_delay_init(void)
	334	{
	335	int r = -ENOMEM;
	336
	337	kdelayd_wq = create_workqueue("kdelayd");
	338	if (!kdelayd_wq) {
	339	DMERR("Couldn't start kdelayd");
	340	goto bad_queue;
	341	}
	342
028867ac	343	delayed_cache = KMEM_CACHE(dm_delay_info, 0);
26b9f228 HM	344	if (!delayed_cache) {
	345	DMERR("Couldn't create delayed bio cache.");
	346	goto bad_memcache;
	347	}
	348
	349	r = dm_register_target(&delay_target);
	350	if (r < 0) {
	351	DMERR("register failed %d", r);
	352	goto bad_register;
	353	}
	354
	355	return 0;
	356
	357	bad_register:
	358	kmem_cache_destroy(delayed_cache);
	359	bad_memcache:
	360	destroy_workqueue(kdelayd_wq);
	361	bad_queue:
	362	return r;
	363	}
	364
	365	static void __exit dm_delay_exit(void)
	366	{
10d3bd09	367	dm_unregister_target(&delay_target);
26b9f228 HM	368	kmem_cache_destroy(delayed_cache);
	369	destroy_workqueue(kdelayd_wq);
	370	}
	371
	372	/* Module hooks */
	373	module_init(dm_delay_init);
	374	module_exit(dm_delay_exit);
	375
	376	MODULE_DESCRIPTION(DM_NAME " delay target");
	377	MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
	378	MODULE_LICENSE("GPL");