diff options
Diffstat (limited to 'drivers/md/dm-delay.c')
| -rw-r--r-- | drivers/md/dm-delay.c | 404 |
1 files changed, 404 insertions, 0 deletions
diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c new file mode 100644 index 000000000..43541c8e2 --- /dev/null +++ b/drivers/md/dm-delay.c @@ -0,0 +1,404 @@ +/* + * 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_class { + struct dm_dev *dev; + sector_t start; + unsigned int delay; + unsigned int ops; +}; + +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; + bool may_delay; + + struct delay_class read; + struct delay_class write; + struct delay_class flush; + + int argc; +}; + +struct dm_delay_info { + struct delay_c *context; + struct delay_class *class; + struct list_head list; + unsigned long expires; +}; + +static DEFINE_MUTEX(delayed_bios_lock); + +static void handle_delayed_timer(struct timer_list *t) +{ + struct delay_c *dc = from_timer(dc, t, delay_timer); + + 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; + dm_submit_bio_remap(bio, NULL); + 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; + unsigned long 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); + delayed->class->ops--; + 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)); +} + +static void delay_dtr(struct dm_target *ti) +{ + struct delay_c *dc = ti->private; + + if (dc->kdelayd_wq) + destroy_workqueue(dc->kdelayd_wq); + + if (dc->read.dev) + dm_put_device(ti, dc->read.dev); + if (dc->write.dev) + dm_put_device(ti, dc->write.dev); + if (dc->flush.dev) + dm_put_device(ti, dc->flush.dev); + + mutex_destroy(&dc->timer_lock); + + kfree(dc); +} + +static int delay_class_ctr(struct dm_target *ti, struct delay_class *c, char **argv) +{ + int ret; + unsigned long long tmpll; + char dummy; + + if (sscanf(argv[1], "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) { + ti->error = "Invalid device sector"; + return -EINVAL; + } + c->start = tmpll; + + if (sscanf(argv[2], "%u%c", &c->delay, &dummy) != 1) { + ti->error = "Invalid delay"; + return -EINVAL; + } + + ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &c->dev); + if (ret) { + ti->error = "Device lookup failed"; + return ret; + } + + return 0; +} + +/* + * Mapping parameters: + * <device> <offset> <delay> [<write_device> <write_offset> <write_delay>] + * + * With separate write parameters, the first set is only used for reads. + * Offsets are specified in sectors. + * Delays are specified in milliseconds. + */ +static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv) +{ + struct delay_c *dc; + int ret; + + if (argc != 3 && argc != 6 && argc != 9) { + ti->error = "Requires exactly 3, 6 or 9 arguments"; + return -EINVAL; + } + + dc = kzalloc(sizeof(*dc), GFP_KERNEL); + if (!dc) { + ti->error = "Cannot allocate context"; + return -ENOMEM; + } + + ti->private = dc; + timer_setup(&dc->delay_timer, handle_delayed_timer, 0); + INIT_WORK(&dc->flush_expired_bios, flush_expired_bios); + INIT_LIST_HEAD(&dc->delayed_bios); + mutex_init(&dc->timer_lock); + dc->may_delay = true; + dc->argc = argc; + + ret = delay_class_ctr(ti, &dc->read, argv); + if (ret) + goto bad; + + if (argc == 3) { + ret = delay_class_ctr(ti, &dc->write, argv); + if (ret) + goto bad; + ret = delay_class_ctr(ti, &dc->flush, argv); + if (ret) + goto bad; + goto out; + } + + ret = delay_class_ctr(ti, &dc->write, argv + 3); + if (ret) + goto bad; + if (argc == 6) { + ret = delay_class_ctr(ti, &dc->flush, argv + 3); + if (ret) + goto bad; + goto out; + } + + ret = delay_class_ctr(ti, &dc->flush, argv + 6); + if (ret) + goto bad; + +out: + dc->kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0); + if (!dc->kdelayd_wq) { + ret = -EINVAL; + DMERR("Couldn't start kdelayd"); + goto bad; + } + + ti->num_flush_bios = 1; + ti->num_discard_bios = 1; + ti->accounts_remapped_io = true; + ti->per_io_data_size = sizeof(struct dm_delay_info); + return 0; + +bad: + delay_dtr(ti); + return ret; +} + +static int delay_bio(struct delay_c *dc, struct delay_class *c, struct bio *bio) +{ + struct dm_delay_info *delayed; + unsigned long expires = 0; + + if (!c->delay) + return DM_MAPIO_REMAPPED; + + delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info)); + + delayed->context = dc; + delayed->expires = expires = jiffies + msecs_to_jiffies(c->delay); + + mutex_lock(&delayed_bios_lock); + if (unlikely(!dc->may_delay)) { + mutex_unlock(&delayed_bios_lock); + return DM_MAPIO_REMAPPED; + } + c->ops++; + list_add_tail(&delayed->list, &dc->delayed_bios); + mutex_unlock(&delayed_bios_lock); + + queue_timeout(dc, expires); + + return DM_MAPIO_SUBMITTED; +} + +static void delay_presuspend(struct dm_target *ti) +{ + struct delay_c *dc = ti->private; + + mutex_lock(&delayed_bios_lock); + dc->may_delay = false; + mutex_unlock(&delayed_bios_lock); + + 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; + + dc->may_delay = true; +} + +static int delay_map(struct dm_target *ti, struct bio *bio) +{ + struct delay_c *dc = ti->private; + struct delay_class *c; + struct dm_delay_info *delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info)); + + if (bio_data_dir(bio) == WRITE) { + if (unlikely(bio->bi_opf & REQ_PREFLUSH)) + c = &dc->flush; + else + c = &dc->write; + } else { + c = &dc->read; + } + delayed->class = c; + bio_set_dev(bio, c->dev->bdev); + bio->bi_iter.bi_sector = c->start + dm_target_offset(ti, bio->bi_iter.bi_sector); + + return delay_bio(dc, c, bio); +} + +#define DMEMIT_DELAY_CLASS(c) \ + DMEMIT("%s %llu %u", (c)->dev->name, (unsigned long long)(c)->start, (c)->delay) + +static void delay_status(struct dm_target *ti, status_type_t type, + unsigned int status_flags, char *result, unsigned int maxlen) +{ + struct delay_c *dc = ti->private; + int sz = 0; + + switch (type) { + case STATUSTYPE_INFO: + DMEMIT("%u %u %u", dc->read.ops, dc->write.ops, dc->flush.ops); + break; + + case STATUSTYPE_TABLE: + DMEMIT_DELAY_CLASS(&dc->read); + if (dc->argc >= 6) { + DMEMIT(" "); + DMEMIT_DELAY_CLASS(&dc->write); + } + if (dc->argc >= 9) { + DMEMIT(" "); + DMEMIT_DELAY_CLASS(&dc->flush); + } + break; + + case STATUSTYPE_IMA: + *result = '\0'; + 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->read.dev, dc->read.start, ti->len, data); + if (ret) + goto out; + ret = fn(ti, dc->write.dev, dc->write.start, ti->len, data); + if (ret) + goto out; + ret = fn(ti, dc->flush.dev, dc->flush.start, ti->len, data); + if (ret) + goto out; + +out: + return ret; +} + +static struct target_type delay_target = { + .name = "delay", + .version = {1, 3, 0}, + .features = DM_TARGET_PASSES_INTEGRITY, + .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 <mauelshagen@redhat.com>"); +MODULE_LICENSE("GPL"); |