| /* |
| * 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/raid/md_u.h> |
| #include <linux/seq_file.h> |
| #include "md.h" |
| #include "multipath.h" |
| |
| #define MAX_WORK_PER_DISK 128 |
| |
| #define NR_RESERVED_BUFS 32 |
| |
| |
| static int multipath_map (multipath_conf_t *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++) { |
| mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev); |
| if (rdev && test_bit(In_sync, &rdev->flags)) { |
| atomic_inc(&rdev->nr_pending); |
| rcu_read_unlock(); |
| return i; |
| } |
| } |
| rcu_read_unlock(); |
| |
| printk(KERN_ERR "multipath_map(): no more operational IO paths?\n"); |
| return (-1); |
| } |
| |
| static void multipath_reschedule_retry (struct multipath_bh *mp_bh) |
| { |
| unsigned long flags; |
| mddev_t *mddev = mp_bh->mddev; |
| multipath_conf_t *conf = mddev_to_conf(mddev); |
| |
| 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, int err) |
| { |
| struct bio *bio = mp_bh->master_bio; |
| multipath_conf_t *conf = mddev_to_conf(mp_bh->mddev); |
| |
| bio_endio(bio, err); |
| mempool_free(mp_bh, conf->pool); |
| } |
| |
| static void multipath_end_request(struct bio *bio, int error) |
| { |
| int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); |
| struct multipath_bh * mp_bh = (struct multipath_bh *)(bio->bi_private); |
| multipath_conf_t *conf = mddev_to_conf(mp_bh->mddev); |
| mdk_rdev_t *rdev = conf->multipaths[mp_bh->path].rdev; |
| |
| if (uptodate) |
| multipath_end_bh_io(mp_bh, 0); |
| else if (!bio_rw_ahead(bio)) { |
| /* |
| * oops, IO error: |
| */ |
| char b[BDEVNAME_SIZE]; |
| md_error (mp_bh->mddev, rdev); |
| printk(KERN_ERR "multipath: %s: rescheduling sector %llu\n", |
| bdevname(rdev->bdev,b), |
| (unsigned long long)bio->bi_sector); |
| multipath_reschedule_retry(mp_bh); |
| } else |
| multipath_end_bh_io(mp_bh, error); |
| rdev_dec_pending(rdev, conf->mddev); |
| } |
| |
| static void unplug_slaves(mddev_t *mddev) |
| { |
| multipath_conf_t *conf = mddev_to_conf(mddev); |
| int i; |
| |
| rcu_read_lock(); |
| for (i=0; i<mddev->raid_disks; i++) { |
| mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev); |
| if (rdev && !test_bit(Faulty, &rdev->flags) |
| && atomic_read(&rdev->nr_pending)) { |
| struct request_queue *r_queue = bdev_get_queue(rdev->bdev); |
| |
| atomic_inc(&rdev->nr_pending); |
| rcu_read_unlock(); |
| |
| blk_unplug(r_queue); |
| |
| rdev_dec_pending(rdev, mddev); |
| rcu_read_lock(); |
| } |
| } |
| rcu_read_unlock(); |
| } |
| |
| static void multipath_unplug(struct request_queue *q) |
| { |
| unplug_slaves(q->queuedata); |
| } |
| |
| |
| static int multipath_make_request (struct request_queue *q, struct bio * bio) |
| { |
| mddev_t *mddev = q->queuedata; |
| multipath_conf_t *conf = mddev_to_conf(mddev); |
| struct multipath_bh * mp_bh; |
| struct multipath_info *multipath; |
| const int rw = bio_data_dir(bio); |
| int cpu; |
| |
| if (unlikely(bio_barrier(bio))) { |
| bio_endio(bio, -EOPNOTSUPP); |
| return 0; |
| } |
| |
| mp_bh = mempool_alloc(conf->pool, GFP_NOIO); |
| |
| mp_bh->master_bio = bio; |
| mp_bh->mddev = mddev; |
| |
| cpu = part_stat_lock(); |
| part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]); |
| part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], |
| bio_sectors(bio)); |
| part_stat_unlock(); |
| |
| mp_bh->path = multipath_map(conf); |
| if (mp_bh->path < 0) { |
| bio_endio(bio, -EIO); |
| mempool_free(mp_bh, conf->pool); |
| return 0; |
| } |
| multipath = conf->multipaths + mp_bh->path; |
| |
| mp_bh->bio = *bio; |
| mp_bh->bio.bi_sector += multipath->rdev->data_offset; |
| mp_bh->bio.bi_bdev = multipath->rdev->bdev; |
| mp_bh->bio.bi_rw |= (1 << BIO_RW_FAILFAST_TRANSPORT); |
| mp_bh->bio.bi_end_io = multipath_end_request; |
| mp_bh->bio.bi_private = mp_bh; |
| generic_make_request(&mp_bh->bio); |
| return 0; |
| } |
| |
| static void multipath_status (struct seq_file *seq, mddev_t *mddev) |
| { |
| multipath_conf_t *conf = mddev_to_conf(mddev); |
| int i; |
| |
| seq_printf (seq, " [%d/%d] [", conf->raid_disks, |
| conf->working_disks); |
| for (i = 0; i < conf->raid_disks; i++) |
| seq_printf (seq, "%s", |
| conf->multipaths[i].rdev && |
| test_bit(In_sync, &conf->multipaths[i].rdev->flags) ? "U" : "_"); |
| seq_printf (seq, "]"); |
| } |
| |
| static int multipath_congested(void *data, int bits) |
| { |
| mddev_t *mddev = data; |
| multipath_conf_t *conf = mddev_to_conf(mddev); |
| int i, ret = 0; |
| |
| rcu_read_lock(); |
| for (i = 0; i < mddev->raid_disks ; i++) { |
| mdk_rdev_t *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 (mddev_t *mddev, mdk_rdev_t *rdev) |
| { |
| multipath_conf_t *conf = mddev_to_conf(mddev); |
| |
| if (conf->working_disks <= 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. |
| */ |
| printk(KERN_ALERT |
| "multipath: only one IO path left and IO error.\n"); |
| /* leave it active... it's all we have */ |
| } else { |
| /* |
| * Mark disk as unusable |
| */ |
| if (!test_bit(Faulty, &rdev->flags)) { |
| char b[BDEVNAME_SIZE]; |
| clear_bit(In_sync, &rdev->flags); |
| set_bit(Faulty, &rdev->flags); |
| set_bit(MD_CHANGE_DEVS, &mddev->flags); |
| conf->working_disks--; |
| mddev->degraded++; |
| printk(KERN_ALERT "multipath: IO failure on %s," |
| " disabling IO path.\n" |
| "multipath: Operation continuing" |
| " on %d IO paths.\n", |
| bdevname (rdev->bdev,b), |
| conf->working_disks); |
| } |
| } |
| } |
| |
| static void print_multipath_conf (multipath_conf_t *conf) |
| { |
| int i; |
| struct multipath_info *tmp; |
| |
| printk("MULTIPATH conf printout:\n"); |
| if (!conf) { |
| printk("(conf==NULL)\n"); |
| return; |
| } |
| printk(" --- wd:%d rd:%d\n", conf->working_disks, |
| conf->raid_disks); |
| |
| for (i = 0; i < conf->raid_disks; i++) { |
| char b[BDEVNAME_SIZE]; |
| tmp = conf->multipaths + i; |
| if (tmp->rdev) |
| printk(" disk%d, o:%d, dev:%s\n", |
| i,!test_bit(Faulty, &tmp->rdev->flags), |
| bdevname(tmp->rdev->bdev,b)); |
| } |
| } |
| |
| |
| static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev) |
| { |
| multipath_conf_t *conf = mddev->private; |
| struct request_queue *q; |
| 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) { |
| q = rdev->bdev->bd_disk->queue; |
| blk_queue_stack_limits(mddev->queue, q); |
| |
| /* as we don't honour merge_bvec_fn, we must never risk |
| * violating it, so limit ->max_sector to one PAGE, as |
| * a one page request is never in violation. |
| * (Note: it is very unlikely that a device with |
| * merge_bvec_fn will be involved in multipath.) |
| */ |
| if (q->merge_bvec_fn && |
| mddev->queue->max_sectors > (PAGE_SIZE>>9)) |
| blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9); |
| |
| conf->working_disks++; |
| mddev->degraded--; |
| rdev->raid_disk = path; |
| set_bit(In_sync, &rdev->flags); |
| rcu_assign_pointer(p->rdev, rdev); |
| err = 0; |
| break; |
| } |
| |
| print_multipath_conf(conf); |
| |
| return err; |
| } |
| |
| static int multipath_remove_disk(mddev_t *mddev, int number) |
| { |
| multipath_conf_t *conf = mddev->private; |
| int err = 0; |
| mdk_rdev_t *rdev; |
| struct multipath_info *p = conf->multipaths + number; |
| |
| print_multipath_conf(conf); |
| |
| rdev = p->rdev; |
| if (rdev) { |
| if (test_bit(In_sync, &rdev->flags) || |
| atomic_read(&rdev->nr_pending)) { |
| printk(KERN_ERR "hot-remove-disk, slot %d is identified" |
| " but is still operational!\n", number); |
| err = -EBUSY; |
| goto abort; |
| } |
| p->rdev = NULL; |
| synchronize_rcu(); |
| if (atomic_read(&rdev->nr_pending)) { |
| /* lost the race, try later */ |
| err = -EBUSY; |
| p->rdev = rdev; |
| } |
| } |
| 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 (mddev_t *mddev) |
| { |
| struct multipath_bh *mp_bh; |
| struct bio *bio; |
| unsigned long flags; |
| multipath_conf_t *conf = mddev_to_conf(mddev); |
| 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_sector = mp_bh->master_bio->bi_sector; |
| |
| if ((mp_bh->path = multipath_map (conf))<0) { |
| printk(KERN_ALERT "multipath: %s: unrecoverable IO read" |
| " error for block %llu\n", |
| bdevname(bio->bi_bdev,b), |
| (unsigned long long)bio->bi_sector); |
| multipath_end_bh_io(mp_bh, -EIO); |
| } else { |
| printk(KERN_ERR "multipath: %s: redirecting sector %llu" |
| " to another IO path\n", |
| bdevname(bio->bi_bdev,b), |
| (unsigned long long)bio->bi_sector); |
| *bio = *(mp_bh->master_bio); |
| bio->bi_sector += conf->multipaths[mp_bh->path].rdev->data_offset; |
| bio->bi_bdev = conf->multipaths[mp_bh->path].rdev->bdev; |
| bio->bi_rw |= (1 << BIO_RW_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(mddev_t *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 (mddev_t *mddev) |
| { |
| multipath_conf_t *conf; |
| int disk_idx; |
| struct multipath_info *disk; |
| mdk_rdev_t *rdev; |
| |
| if (mddev->level != LEVEL_MULTIPATH) { |
| printk("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_stop()] |
| */ |
| mddev->queue->queue_lock = &mddev->queue->__queue_lock; |
| |
| conf = kzalloc(sizeof(multipath_conf_t), GFP_KERNEL); |
| mddev->private = conf; |
| if (!conf) { |
| printk(KERN_ERR |
| "multipath: couldn't allocate memory for %s\n", |
| mdname(mddev)); |
| goto out; |
| } |
| |
| conf->multipaths = kzalloc(sizeof(struct multipath_info)*mddev->raid_disks, |
| GFP_KERNEL); |
| if (!conf->multipaths) { |
| printk(KERN_ERR |
| "multipath: couldn't allocate memory for %s\n", |
| mdname(mddev)); |
| goto out_free_conf; |
| } |
| |
| conf->working_disks = 0; |
| list_for_each_entry(rdev, &mddev->disks, same_set) { |
| disk_idx = rdev->raid_disk; |
| if (disk_idx < 0 || |
| disk_idx >= mddev->raid_disks) |
| continue; |
| |
| disk = conf->multipaths + disk_idx; |
| disk->rdev = rdev; |
| |
| blk_queue_stack_limits(mddev->queue, |
| rdev->bdev->bd_disk->queue); |
| /* as we don't honour merge_bvec_fn, we must never risk |
| * violating it, not that we ever expect a device with |
| * a merge_bvec_fn to be involved in multipath */ |
| if (rdev->bdev->bd_disk->queue->merge_bvec_fn && |
| mddev->queue->max_sectors > (PAGE_SIZE>>9)) |
| blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9); |
| |
| if (!test_bit(Faulty, &rdev->flags)) |
| conf->working_disks++; |
| } |
| |
| conf->raid_disks = mddev->raid_disks; |
| conf->mddev = mddev; |
| spin_lock_init(&conf->device_lock); |
| INIT_LIST_HEAD(&conf->retry_list); |
| |
| if (!conf->working_disks) { |
| printk(KERN_ERR "multipath: no operational IO paths for %s\n", |
| mdname(mddev)); |
| goto out_free_conf; |
| } |
| mddev->degraded = conf->raid_disks - conf->working_disks; |
| |
| conf->pool = mempool_create_kzalloc_pool(NR_RESERVED_BUFS, |
| sizeof(struct multipath_bh)); |
| if (conf->pool == NULL) { |
| printk(KERN_ERR |
| "multipath: couldn't allocate memory for %s\n", |
| mdname(mddev)); |
| goto out_free_conf; |
| } |
| |
| { |
| mddev->thread = md_register_thread(multipathd, mddev, "%s_multipath"); |
| if (!mddev->thread) { |
| printk(KERN_ERR "multipath: couldn't allocate thread" |
| " for %s\n", mdname(mddev)); |
| goto out_free_conf; |
| } |
| } |
| |
| printk(KERN_INFO |
| "multipath: array %s active with %d out of %d IO paths\n", |
| mdname(mddev), conf->working_disks, mddev->raid_disks); |
| /* |
| * Ok, everything is just fine now |
| */ |
| mddev->array_sectors = multipath_size(mddev, 0, 0); |
| |
| mddev->queue->unplug_fn = multipath_unplug; |
| mddev->queue->backing_dev_info.congested_fn = multipath_congested; |
| mddev->queue->backing_dev_info.congested_data = mddev; |
| |
| return 0; |
| |
| out_free_conf: |
| if (conf->pool) |
| mempool_destroy(conf->pool); |
| kfree(conf->multipaths); |
| kfree(conf); |
| mddev->private = NULL; |
| out: |
| return -EIO; |
| } |
| |
| |
| static int multipath_stop (mddev_t *mddev) |
| { |
| multipath_conf_t *conf = mddev_to_conf(mddev); |
| |
| md_unregister_thread(mddev->thread); |
| mddev->thread = NULL; |
| blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ |
| mempool_destroy(conf->pool); |
| kfree(conf->multipaths); |
| kfree(conf); |
| mddev->private = NULL; |
| return 0; |
| } |
| |
| static struct mdk_personality multipath_personality = |
| { |
| .name = "multipath", |
| .level = LEVEL_MULTIPATH, |
| .owner = THIS_MODULE, |
| .make_request = multipath_make_request, |
| .run = multipath_run, |
| .stop = multipath_stop, |
| .status = multipath_status, |
| .error_handler = multipath_error, |
| .hot_add_disk = multipath_add_disk, |
| .hot_remove_disk= multipath_remove_disk, |
| .size = multipath_size, |
| }; |
| |
| 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_ALIAS("md-personality-7"); /* MULTIPATH */ |
| MODULE_ALIAS("md-multipath"); |
| MODULE_ALIAS("md-level--4"); |