drivers/md/dm-delay.c - maze/linux - Git at Google

 /*
  * 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 "dm.h"
 #include "dm-bio-list.h"

 #define DM_MSG_PREFIX "delay"

 struct delay_c {
 	struct timer_list delay_timer;
 	struct semaphore 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)
 {
 	down(&dc->timer_lock);

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

 	up(&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;
 	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;
 	}

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

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

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

 	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";
 		dm_put_device(ti, dc->dev_read);
 		goto bad;
 	}

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

 	init_timer(&dc->delay_timer);
 	dc->delay_timer.function = handle_delayed_timer;
 	dc->delay_timer.data = (unsigned long)dc;

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

 	ti->private = dc;
 	return 0;

 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)
 {
 	int r = dm_unregister_target(&delay_target);

 	if (r < 0)
 		DMERR("unregister failed %d", r);

 	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");
	/*
	* 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 "dm.h"
	#include "dm-bio-list.h"

	#define DM_MSG_PREFIX "delay"

	struct delay_c {
	struct timer_list delay_timer;
	struct semaphore 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)
	{
	down(&dc->timer_lock);

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

	up(&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;
	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;
	}

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

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

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

	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";
	dm_put_device(ti, dc->dev_read);
	goto bad;
	}

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

	init_timer(&dc->delay_timer);
	dc->delay_timer.function = handle_delayed_timer;
	dc->delay_timer.data = (unsigned long)dc;

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

	ti->private = dc;
	return 0;

	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)
	{
	int r = dm_unregister_target(&delay_target);

	if (r < 0)
	DMERR("unregister failed %d", r);

	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");