/* * 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_class { struct dm_dev *dev; sector_t start; unsigned delay; unsigned 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; atomic_t 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; 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; 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; 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: * [ ] * * 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); atomic_set(&dc->may_delay, 1); 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->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 || !atomic_read(&dc->may_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); 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; 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; 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); if (bio_sectors(bio)) 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 status_flags, char *result, unsigned 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; } } 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, 2, 1}, .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 "); MODULE_LICENSE("GPL");