diff options
Diffstat (limited to 'drivers/md/md-multipath.c')
| -rw-r--r-- | drivers/md/md-multipath.c | 507 |
1 files changed, 507 insertions, 0 deletions
diff --git a/drivers/md/md-multipath.c b/drivers/md/md-multipath.c new file mode 100644 index 000000000000..e40065bdbfc8 --- /dev/null +++ b/drivers/md/md-multipath.c @@ -0,0 +1,507 @@ +/* + * multipath.c : Multiple Devices driver for Linux + * + * Copyright (C) 1999, 2000, 2001 Ingo Molnar, Red Hat + * + * Copyright (C) 1996, 1997, 1998 Ingo Molnar, Miguel de Icaza, Gadi Oxman + * + * MULTIPATH management functions. + * + * derived from raid1.c. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2, or (at your option) + * any later version. + * + * You should have received a copy of the GNU General Public License + * (for example /usr/src/linux/COPYING); if not, write to the Free + * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/blkdev.h> +#include <linux/module.h> +#include <linux/raid/md_u.h> +#include <linux/seq_file.h> +#include <linux/slab.h> +#include "md.h" +#include "md-multipath.h" + +#define MAX_WORK_PER_DISK 128 + +#define NR_RESERVED_BUFS 32 + +static int multipath_map (struct mpconf *conf) +{ + int i, disks = conf->raid_disks; + + /* + * Later we do read balancing on the read side + * now we use the first available disk. + */ + + rcu_read_lock(); + for (i = 0; i < disks; i++) { + struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev); + if (rdev && test_bit(In_sync, &rdev->flags) && + !test_bit(Faulty, &rdev->flags)) { + atomic_inc(&rdev->nr_pending); + rcu_read_unlock(); + return i; + } + } + rcu_read_unlock(); + + pr_crit_ratelimited("multipath_map(): no more operational IO paths?\n"); + return (-1); +} + +static void multipath_reschedule_retry (struct multipath_bh *mp_bh) +{ + unsigned long flags; + struct mddev *mddev = mp_bh->mddev; + struct mpconf *conf = mddev->private; + + spin_lock_irqsave(&conf->device_lock, flags); + list_add(&mp_bh->retry_list, &conf->retry_list); + spin_unlock_irqrestore(&conf->device_lock, flags); + md_wakeup_thread(mddev->thread); +} + +/* + * multipath_end_bh_io() is called when we have finished servicing a multipathed + * operation and are ready to return a success/failure code to the buffer + * cache layer. + */ +static void multipath_end_bh_io(struct multipath_bh *mp_bh, blk_status_t status) +{ + struct bio *bio = mp_bh->master_bio; + struct mpconf *conf = mp_bh->mddev->private; + + bio->bi_status = status; + bio_endio(bio); + mempool_free(mp_bh, conf->pool); +} + +static void multipath_end_request(struct bio *bio) +{ + struct multipath_bh *mp_bh = bio->bi_private; + struct mpconf *conf = mp_bh->mddev->private; + struct md_rdev *rdev = conf->multipaths[mp_bh->path].rdev; + + if (!bio->bi_status) + multipath_end_bh_io(mp_bh, 0); + else if (!(bio->bi_opf & REQ_RAHEAD)) { + /* + * oops, IO error: + */ + char b[BDEVNAME_SIZE]; + md_error (mp_bh->mddev, rdev); + pr_info("multipath: %s: rescheduling sector %llu\n", + bdevname(rdev->bdev,b), + (unsigned long long)bio->bi_iter.bi_sector); + multipath_reschedule_retry(mp_bh); + } else + multipath_end_bh_io(mp_bh, bio->bi_status); + rdev_dec_pending(rdev, conf->mddev); +} + +static bool multipath_make_request(struct mddev *mddev, struct bio * bio) +{ + struct mpconf *conf = mddev->private; + struct multipath_bh * mp_bh; + struct multipath_info *multipath; + + if (unlikely(bio->bi_opf & REQ_PREFLUSH)) { + md_flush_request(mddev, bio); + return true; + } + + mp_bh = mempool_alloc(conf->pool, GFP_NOIO); + + mp_bh->master_bio = bio; + mp_bh->mddev = mddev; + + mp_bh->path = multipath_map(conf); + if (mp_bh->path < 0) { + bio_io_error(bio); + mempool_free(mp_bh, conf->pool); + return true; + } + multipath = conf->multipaths + mp_bh->path; + + bio_init(&mp_bh->bio, NULL, 0); + __bio_clone_fast(&mp_bh->bio, bio); + + mp_bh->bio.bi_iter.bi_sector += multipath->rdev->data_offset; + bio_set_dev(&mp_bh->bio, multipath->rdev->bdev); + mp_bh->bio.bi_opf |= REQ_FAILFAST_TRANSPORT; + mp_bh->bio.bi_end_io = multipath_end_request; + mp_bh->bio.bi_private = mp_bh; + mddev_check_writesame(mddev, &mp_bh->bio); + mddev_check_write_zeroes(mddev, &mp_bh->bio); + generic_make_request(&mp_bh->bio); + return true; +} + +static void multipath_status(struct seq_file *seq, struct mddev *mddev) +{ + struct mpconf *conf = mddev->private; + int i; + + seq_printf (seq, " [%d/%d] [", conf->raid_disks, + conf->raid_disks - mddev->degraded); + rcu_read_lock(); + for (i = 0; i < conf->raid_disks; i++) { + struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev); + seq_printf (seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_"); + } + rcu_read_unlock(); + seq_printf (seq, "]"); +} + +static int multipath_congested(struct mddev *mddev, int bits) +{ + struct mpconf *conf = mddev->private; + int i, ret = 0; + + rcu_read_lock(); + for (i = 0; i < mddev->raid_disks ; i++) { + struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev); + if (rdev && !test_bit(Faulty, &rdev->flags)) { + struct request_queue *q = bdev_get_queue(rdev->bdev); + + ret |= bdi_congested(q->backing_dev_info, bits); + /* Just like multipath_map, we just check the + * first available device + */ + break; + } + } + rcu_read_unlock(); + return ret; +} + +/* + * Careful, this can execute in IRQ contexts as well! + */ +static void multipath_error (struct mddev *mddev, struct md_rdev *rdev) +{ + struct mpconf *conf = mddev->private; + char b[BDEVNAME_SIZE]; + + if (conf->raid_disks - mddev->degraded <= 1) { + /* + * Uh oh, we can do nothing if this is our last path, but + * first check if this is a queued request for a device + * which has just failed. + */ + pr_warn("multipath: only one IO path left and IO error.\n"); + /* leave it active... it's all we have */ + return; + } + /* + * Mark disk as unusable + */ + if (test_and_clear_bit(In_sync, &rdev->flags)) { + unsigned long flags; + spin_lock_irqsave(&conf->device_lock, flags); + mddev->degraded++; + spin_unlock_irqrestore(&conf->device_lock, flags); + } + set_bit(Faulty, &rdev->flags); + set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags); + pr_err("multipath: IO failure on %s, disabling IO path.\n" + "multipath: Operation continuing on %d IO paths.\n", + bdevname(rdev->bdev, b), + conf->raid_disks - mddev->degraded); +} + +static void print_multipath_conf (struct mpconf *conf) +{ + int i; + struct multipath_info *tmp; + + pr_debug("MULTIPATH conf printout:\n"); + if (!conf) { + pr_debug("(conf==NULL)\n"); + return; + } + pr_debug(" --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded, + conf->raid_disks); + + for (i = 0; i < conf->raid_disks; i++) { + char b[BDEVNAME_SIZE]; + tmp = conf->multipaths + i; + if (tmp->rdev) + pr_debug(" disk%d, o:%d, dev:%s\n", + i,!test_bit(Faulty, &tmp->rdev->flags), + bdevname(tmp->rdev->bdev,b)); + } +} + +static int multipath_add_disk(struct mddev *mddev, struct md_rdev *rdev) +{ + struct mpconf *conf = mddev->private; + int err = -EEXIST; + int path; + struct multipath_info *p; + int first = 0; + int last = mddev->raid_disks - 1; + + if (rdev->raid_disk >= 0) + first = last = rdev->raid_disk; + + print_multipath_conf(conf); + + for (path = first; path <= last; path++) + if ((p=conf->multipaths+path)->rdev == NULL) { + disk_stack_limits(mddev->gendisk, rdev->bdev, + rdev->data_offset << 9); + + err = md_integrity_add_rdev(rdev, mddev); + if (err) + break; + spin_lock_irq(&conf->device_lock); + mddev->degraded--; + rdev->raid_disk = path; + set_bit(In_sync, &rdev->flags); + spin_unlock_irq(&conf->device_lock); + rcu_assign_pointer(p->rdev, rdev); + err = 0; + break; + } + + print_multipath_conf(conf); + + return err; +} + +static int multipath_remove_disk(struct mddev *mddev, struct md_rdev *rdev) +{ + struct mpconf *conf = mddev->private; + int err = 0; + int number = rdev->raid_disk; + struct multipath_info *p = conf->multipaths + number; + + print_multipath_conf(conf); + + if (rdev == p->rdev) { + if (test_bit(In_sync, &rdev->flags) || + atomic_read(&rdev->nr_pending)) { + pr_warn("hot-remove-disk, slot %d is identified but is still operational!\n", number); + err = -EBUSY; + goto abort; + } + p->rdev = NULL; + if (!test_bit(RemoveSynchronized, &rdev->flags)) { + synchronize_rcu(); + if (atomic_read(&rdev->nr_pending)) { + /* lost the race, try later */ + err = -EBUSY; + p->rdev = rdev; + goto abort; + } + } + err = md_integrity_register(mddev); + } +abort: + + print_multipath_conf(conf); + return err; +} + +/* + * This is a kernel thread which: + * + * 1. Retries failed read operations on working multipaths. + * 2. Updates the raid superblock when problems encounter. + * 3. Performs writes following reads for array syncronising. + */ + +static void multipathd(struct md_thread *thread) +{ + struct mddev *mddev = thread->mddev; + struct multipath_bh *mp_bh; + struct bio *bio; + unsigned long flags; + struct mpconf *conf = mddev->private; + struct list_head *head = &conf->retry_list; + + md_check_recovery(mddev); + for (;;) { + char b[BDEVNAME_SIZE]; + spin_lock_irqsave(&conf->device_lock, flags); + if (list_empty(head)) + break; + mp_bh = list_entry(head->prev, struct multipath_bh, retry_list); + list_del(head->prev); + spin_unlock_irqrestore(&conf->device_lock, flags); + + bio = &mp_bh->bio; + bio->bi_iter.bi_sector = mp_bh->master_bio->bi_iter.bi_sector; + + if ((mp_bh->path = multipath_map (conf))<0) { + pr_err("multipath: %s: unrecoverable IO read error for block %llu\n", + bio_devname(bio, b), + (unsigned long long)bio->bi_iter.bi_sector); + multipath_end_bh_io(mp_bh, BLK_STS_IOERR); + } else { + pr_err("multipath: %s: redirecting sector %llu to another IO path\n", + bio_devname(bio, b), + (unsigned long long)bio->bi_iter.bi_sector); + *bio = *(mp_bh->master_bio); + bio->bi_iter.bi_sector += + conf->multipaths[mp_bh->path].rdev->data_offset; + bio_set_dev(bio, conf->multipaths[mp_bh->path].rdev->bdev); + bio->bi_opf |= REQ_FAILFAST_TRANSPORT; + bio->bi_end_io = multipath_end_request; + bio->bi_private = mp_bh; + generic_make_request(bio); + } + } + spin_unlock_irqrestore(&conf->device_lock, flags); +} + +static sector_t multipath_size(struct mddev *mddev, sector_t sectors, int raid_disks) +{ + WARN_ONCE(sectors || raid_disks, + "%s does not support generic reshape\n", __func__); + + return mddev->dev_sectors; +} + +static int multipath_run (struct mddev *mddev) +{ + struct mpconf *conf; + int disk_idx; + struct multipath_info *disk; + struct md_rdev *rdev; + int working_disks; + + if (md_check_no_bitmap(mddev)) + return -EINVAL; + + if (mddev->level != LEVEL_MULTIPATH) { + pr_warn("multipath: %s: raid level not set to multipath IO (%d)\n", + mdname(mddev), mddev->level); + goto out; + } + /* + * copy the already verified devices into our private MULTIPATH + * bookkeeping area. [whatever we allocate in multipath_run(), + * should be freed in multipath_free()] + */ + + conf = kzalloc(sizeof(struct mpconf), GFP_KERNEL); + mddev->private = conf; + if (!conf) + goto out; + + conf->multipaths = kzalloc(sizeof(struct multipath_info)*mddev->raid_disks, + GFP_KERNEL); + if (!conf->multipaths) + goto out_free_conf; + + working_disks = 0; + rdev_for_each(rdev, mddev) { + disk_idx = rdev->raid_disk; + if (disk_idx < 0 || + disk_idx >= mddev->raid_disks) + continue; + + disk = conf->multipaths + disk_idx; + disk->rdev = rdev; + disk_stack_limits(mddev->gendisk, rdev->bdev, + rdev->data_offset << 9); + + if (!test_bit(Faulty, &rdev->flags)) + working_disks++; + } + + conf->raid_disks = mddev->raid_disks; + conf->mddev = mddev; + spin_lock_init(&conf->device_lock); + INIT_LIST_HEAD(&conf->retry_list); + + if (!working_disks) { + pr_warn("multipath: no operational IO paths for %s\n", + mdname(mddev)); + goto out_free_conf; + } + mddev->degraded = conf->raid_disks - working_disks; + + conf->pool = mempool_create_kmalloc_pool(NR_RESERVED_BUFS, + sizeof(struct multipath_bh)); + if (conf->pool == NULL) + goto out_free_conf; + + mddev->thread = md_register_thread(multipathd, mddev, + "multipath"); + if (!mddev->thread) + goto out_free_conf; + + pr_info("multipath: array %s active with %d out of %d IO paths\n", + mdname(mddev), conf->raid_disks - mddev->degraded, + mddev->raid_disks); + /* + * Ok, everything is just fine now + */ + md_set_array_sectors(mddev, multipath_size(mddev, 0, 0)); + + if (md_integrity_register(mddev)) + goto out_free_conf; + + return 0; + +out_free_conf: + mempool_destroy(conf->pool); + kfree(conf->multipaths); + kfree(conf); + mddev->private = NULL; +out: + return -EIO; +} + +static void multipath_free(struct mddev *mddev, void *priv) +{ + struct mpconf *conf = priv; + + mempool_destroy(conf->pool); + kfree(conf->multipaths); + kfree(conf); +} + +static struct md_personality multipath_personality = +{ + .name = "multipath", + .level = LEVEL_MULTIPATH, + .owner = THIS_MODULE, + .make_request = multipath_make_request, + .run = multipath_run, + .free = multipath_free, + .status = multipath_status, + .error_handler = multipath_error, + .hot_add_disk = multipath_add_disk, + .hot_remove_disk= multipath_remove_disk, + .size = multipath_size, + .congested = multipath_congested, +}; + +static int __init multipath_init (void) +{ + return register_md_personality (&multipath_personality); +} + +static void __exit multipath_exit (void) +{ + unregister_md_personality (&multipath_personality); +} + +module_init(multipath_init); +module_exit(multipath_exit); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("simple multi-path personality for MD"); +MODULE_ALIAS("md-personality-7"); /* MULTIPATH */ +MODULE_ALIAS("md-multipath"); +MODULE_ALIAS("md-level--4"); |