From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- drivers/md/dm-delay.c | 373 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 373 insertions(+) create mode 100644 drivers/md/dm-delay.c (limited to 'drivers/md/dm-delay.c') diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c new file mode 100644 index 000000000..57b6a1901 --- /dev/null +++ b/drivers/md/dm-delay.c @@ -0,0 +1,373 @@ +/* + * 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 +#include +#include +#include +#include + +#include + +#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; + + 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; + unsigned long expires; +}; + +static DEFINE_MUTEX(delayed_bios_lock); + +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)) { + struct bio *bio = dm_bio_from_per_bio_data(delayed, + sizeof(struct dm_delay_info)); + list_del(&delayed->list); + bio_list_add(&flush_bios, bio); + if ((bio_data_dir(bio) == WRITE)) + delayed->context->writes--; + else + delayed->context->reads--; + 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: + * [ ] + * + * 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->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->per_bio_data_size = sizeof(struct dm_delay_info); + ti->private = dc; + return 0; + +bad_queue: + 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); + + 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 = dm_per_bio_data(bio, sizeof(struct dm_delay_info)); + + delayed->context = dc; + delayed->expires = expires = jiffies + msecs_to_jiffies(delay); + + 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_iter.bi_sector = dc->start_write + + dm_target_offset(ti, bio->bi_iter.bi_sector); + + return delay_bio(dc, dc->write_delay, bio); + } + + bio->bi_bdev = dc->dev_read->bdev; + bio->bi_iter.bi_sector = dc->start_read + + dm_target_offset(ti, bio->bi_iter.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; + + r = dm_register_target(&delay_target); + if (r < 0) { + DMERR("register failed %d", r); + goto bad_register; + } + + return 0; + +bad_register: + return r; +} + +static void __exit dm_delay_exit(void) +{ + dm_unregister_target(&delay_target); +} + +/* Module hooks */ +module_init(dm_delay_init); +module_exit(dm_delay_exit); + +MODULE_DESCRIPTION(DM_NAME " delay target"); +MODULE_AUTHOR("Heinz Mauelshagen "); +MODULE_LICENSE("GPL"); -- cgit v1.2.3-54-g00ecf