[deliverable/linux.git] / drivers / md / multipath.c

/*
 * 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 "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)) {
			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;
	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, int err)
{
	struct bio *bio = mp_bh->master_bio;
	struct mpconf *conf = mp_bh->mddev->private;

	bio->bi_error = err;
	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_error)
		multipath_end_bh_io(mp_bh, 0);
	else if (!(bio->bi_rw & REQ_RAHEAD)) {
		/*
		 * 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_iter.bi_sector);
		multipath_reschedule_retry(mp_bh);
	} else
		multipath_end_bh_io(mp_bh, bio->bi_error);
	rdev_dec_pending(rdev, conf->mddev);
}

static void 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_rw & REQ_FLUSH)) {
		md_flush_request(mddev, bio);
		return;
	}

	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;
	}
	multipath = conf->multipaths + mp_bh->path;

	mp_bh->bio = *bio;
	mp_bh->bio.bi_iter.bi_sector += multipath->rdev->data_offset;
	mp_bh->bio.bi_bdev = multipath->rdev->bdev;
	mp_bh->bio.bi_rw |= REQ_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;
}

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);
	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(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.
		 */
		printk(KERN_ALERT
		       "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_CHANGE_DEVS, &mddev->flags);
	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->raid_disks - mddev->degraded);
}

static void print_multipath_conf (struct mpconf *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->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)
			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(struct mddev *mddev, struct md_rdev *rdev)
{
	struct mpconf *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;
			disk_stack_limits(mddev->gendisk, rdev->bdev,
					  rdev->data_offset << 9);

			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;
			md_integrity_add_rdev(rdev, mddev);
			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)) {
			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;
			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) {
			printk(KERN_ALERT "multipath: %s: unrecoverable IO read"
				" error for block %llu\n",
				bdevname(bio->bi_bdev,b),
				(unsigned long long)bio->bi_iter.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_iter.bi_sector);
			*bio = *(mp_bh->master_bio);
			bio->bi_iter.bi_sector +=
				conf->multipaths[mp_bh->path].rdev->data_offset;
			bio->bi_bdev = conf->multipaths[mp_bh->path].rdev->bdev;
			bio->bi_rw |= 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) {
		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_free()]
	 */

	conf = kzalloc(sizeof(struct mpconf), 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;
	}

	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) {
		printk(KERN_ERR "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) {
		printk(KERN_ERR
			"multipath: couldn't allocate memory for %s\n",
			mdname(mddev));
		goto out_free_conf;
	}

	{
		mddev->thread = md_register_thread(multipathd, mddev,
						   "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->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:
	if (conf->pool)
		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");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* multipath.c : Multiple Devices driver for Linux
	3	*
	4	* Copyright (C) 1999, 2000, 2001 Ingo Molnar, Red Hat
	5	*
	6	* Copyright (C) 1996, 1997, 1998 Ingo Molnar, Miguel de Icaza, Gadi Oxman
	7	*
	8	* MULTIPATH management functions.
	9	*
	10	* derived from raid1.c.
	11	*
	12	* This program is free software; you can redistribute it and/or modify
	13	* it under the terms of the GNU General Public License as published by
	14	* the Free Software Foundation; either version 2, or (at your option)
	15	* any later version.
	16	*
	17	* You should have received a copy of the GNU General Public License
	18	* (for example /usr/src/linux/COPYING); if not, write to the Free
	19	* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	20	*/
	21
bff61975	22	#include <linux/blkdev.h>
056075c7	23	#include <linux/module.h>
bff61975	24	#include <linux/raid/md_u.h>
bff61975	25	#include <linux/seq_file.h>
5a0e3ad6	26	#include <linux/slab.h>
43b2e5d8	27	#include "md.h"
ef740c37	28	#include "multipath.h"
1da177e4 LT	29
	30	#define MAX_WORK_PER_DISK 128
	31
	32	#define NR_RESERVED_BUFS 32
	33
69724e28	34	static int multipath_map (struct mpconf *conf)
1da177e4 LT	35	{
	36	int i, disks = conf->raid_disks;
	37
	38	/*
f72ffdd6	39	* Later we do read balancing on the read side
1da177e4 LT	40	* now we use the first available disk.
	41	*/
	42
	43	rcu_read_lock();
	44	for (i = 0; i < disks; i++) {
3cb03002	45	struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev);
b2d444d7	46	if (rdev && test_bit(In_sync, &rdev->flags)) {
1da177e4 LT	47	atomic_inc(&rdev->nr_pending);
	48	rcu_read_unlock();
	49	return i;
	50	}
	51	}
	52	rcu_read_unlock();
	53
	54	printk(KERN_ERR "multipath_map(): no more operational IO paths?\n");
	55	return (-1);
	56	}
	57
	58	static void multipath_reschedule_retry (struct multipath_bh *mp_bh)
	59	{
	60	unsigned long flags;
fd01b88c	61	struct mddev *mddev = mp_bh->mddev;
69724e28	62	struct mpconf *conf = mddev->private;
1da177e4 LT	63
	64	spin_lock_irqsave(&conf->device_lock, flags);
	65	list_add(&mp_bh->retry_list, &conf->retry_list);
	66	spin_unlock_irqrestore(&conf->device_lock, flags);
	67	md_wakeup_thread(mddev->thread);
	68	}
	69
1da177e4 LT	70	/*
	71	* multipath_end_bh_io() is called when we have finished servicing a multipathed
	72	* operation and are ready to return a success/failure code to the buffer
	73	* cache layer.
	74	*/
	75	static void multipath_end_bh_io (struct multipath_bh *mp_bh, int err)
	76	{
	77	struct bio *bio = mp_bh->master_bio;
69724e28	78	struct mpconf *conf = mp_bh->mddev->private;
1da177e4	79
4246a0b6 CH	80	bio->bi_error = err;
4246a0b6 CH	81	bio_endio(bio);
1da177e4 LT	82	mempool_free(mp_bh, conf->pool);
	83	}
	84
4246a0b6	85	static void multipath_end_request(struct bio *bio)
1da177e4	86	{
7b92813c	87	struct multipath_bh *mp_bh = bio->bi_private;
69724e28	88	struct mpconf *conf = mp_bh->mddev->private;
3cb03002	89	struct md_rdev *rdev = conf->multipaths[mp_bh->path].rdev;
1da177e4	90
4246a0b6	91	if (!bio->bi_error)
1da177e4	92	multipath_end_bh_io(mp_bh, 0);
7b6d91da	93	else if (!(bio->bi_rw & REQ_RAHEAD)) {
1da177e4 LT	94	/*
	95	* oops, IO error:
	96	*/
	97	char b[BDEVNAME_SIZE];
	98	md_error (mp_bh->mddev, rdev);
f72ffdd6 N	99	printk(KERN_ERR "multipath: %s: rescheduling sector %llu\n",
f72ffdd6 N	100	bdevname(rdev->bdev,b),
4f024f37	101	(unsigned long long)bio->bi_iter.bi_sector);
1da177e4 LT	102	multipath_reschedule_retry(mp_bh);
1da177e4 LT	103	} else
4246a0b6	104	multipath_end_bh_io(mp_bh, bio->bi_error);
1da177e4	105	rdev_dec_pending(rdev, conf->mddev);
1da177e4 LT	106	}
1da177e4 LT	107
b4fdcb02	108	static void multipath_make_request(struct mddev mddev, struct bio bio)
1da177e4	109	{
69724e28	110	struct mpconf *conf = mddev->private;
1da177e4 LT	111	struct multipath_bh * mp_bh;
	112	struct multipath_info *multipath;
	113
e9c7469b TH	114	if (unlikely(bio->bi_rw & REQ_FLUSH)) {
e9c7469b TH	115	md_flush_request(mddev, bio);
5a7bbad2	116	return;
e5dcdd80 N	117	}
e5dcdd80 N	118
1da177e4 LT	119	mp_bh = mempool_alloc(conf->pool, GFP_NOIO);
	120
	121	mp_bh->master_bio = bio;
	122	mp_bh->mddev = mddev;
	123
1da177e4 LT	124	mp_bh->path = multipath_map(conf);
1da177e4 LT	125	if (mp_bh->path < 0) {
4246a0b6	126	bio_io_error(bio);
1da177e4	127	mempool_free(mp_bh, conf->pool);
5a7bbad2	128	return;
1da177e4 LT	129	}
	130	multipath = conf->multipaths + mp_bh->path;
	131
	132	mp_bh->bio = *bio;
4f024f37	133	mp_bh->bio.bi_iter.bi_sector += multipath->rdev->data_offset;
1da177e4	134	mp_bh->bio.bi_bdev = multipath->rdev->bdev;
7b6d91da	135	mp_bh->bio.bi_rw \|= REQ_FAILFAST_TRANSPORT;
1da177e4 LT	136	mp_bh->bio.bi_end_io = multipath_end_request;
	137	mp_bh->bio.bi_private = mp_bh;
	138	generic_make_request(&mp_bh->bio);
5a7bbad2	139	return;
1da177e4 LT	140	}
1da177e4 LT	141
fd01b88c	142	static void multipath_status (struct seq_file seq, struct mddev mddev)
1da177e4	143	{
69724e28	144	struct mpconf *conf = mddev->private;
1da177e4	145	int i;
f72ffdd6	146
1da177e4	147	seq_printf (seq, " [%d/%d] [", conf->raid_disks,
92f861a7	148	conf->raid_disks - mddev->degraded);
1da177e4 LT	149	for (i = 0; i < conf->raid_disks; i++)
1da177e4 LT	150	seq_printf (seq, "%s",
f72ffdd6	151	conf->multipaths[i].rdev &&
b2d444d7	152	test_bit(In_sync, &conf->multipaths[i].rdev->flags) ? "U" : "_");
1da177e4 LT	153	seq_printf (seq, "]");
	154	}
	155
5c675f83	156	static int multipath_congested(struct mddev *mddev, int bits)
0d129228	157	{
69724e28	158	struct mpconf *conf = mddev->private;
0d129228 N	159	int i, ret = 0;
	160
	161	rcu_read_lock();
	162	for (i = 0; i < mddev->raid_disks ; i++) {
3cb03002	163	struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev);
0d129228	164	if (rdev && !test_bit(Faulty, &rdev->flags)) {
165125e1	165	struct request_queue *q = bdev_get_queue(rdev->bdev);
0d129228 N	166
	167	ret \|= bdi_congested(&q->backing_dev_info, bits);
	168	/* Just like multipath_map, we just check the
	169	* first available device
	170	*/
	171	break;
	172	}
	173	}
	174	rcu_read_unlock();
	175	return ret;
	176	}
1da177e4 LT	177
	178	/*
	179	* Careful, this can execute in IRQ contexts as well!
	180	*/
fd01b88c	181	static void multipath_error (struct mddev mddev, struct md_rdev rdev)
1da177e4	182	{
69724e28	183	struct mpconf *conf = mddev->private;
6f8d0c77	184	char b[BDEVNAME_SIZE];
1da177e4	185
92f861a7	186	if (conf->raid_disks - mddev->degraded <= 1) {
1da177e4 LT	187	/*
	188	* Uh oh, we can do nothing if this is our last path, but
	189	* first check if this is a queued request for a device
	190	* which has just failed.
	191	*/
f72ffdd6	192	printk(KERN_ALERT
6f8d0c77	193	"multipath: only one IO path left and IO error.\n");
1da177e4	194	/* leave it active... it's all we have */
6f8d0c77 N	195	return;
	196	}
	197	/*
	198	* Mark disk as unusable
	199	*/
	200	if (test_and_clear_bit(In_sync, &rdev->flags)) {
	201	unsigned long flags;
	202	spin_lock_irqsave(&conf->device_lock, flags);
	203	mddev->degraded++;
	204	spin_unlock_irqrestore(&conf->device_lock, flags);
1da177e4	205	}
6f8d0c77 N	206	set_bit(Faulty, &rdev->flags);
	207	set_bit(MD_CHANGE_DEVS, &mddev->flags);
	208	printk(KERN_ALERT "multipath: IO failure on %s,"
	209	" disabling IO path.\n"
	210	"multipath: Operation continuing"
	211	" on %d IO paths.\n",
	212	bdevname(rdev->bdev, b),
	213	conf->raid_disks - mddev->degraded);
1da177e4 LT	214	}
1da177e4 LT	215
69724e28	216	static void print_multipath_conf (struct mpconf *conf)
1da177e4 LT	217	{
	218	int i;
	219	struct multipath_info *tmp;
	220
	221	printk("MULTIPATH conf printout:\n");
	222	if (!conf) {
	223	printk("(conf==NULL)\n");
	224	return;
	225	}
92f861a7	226	printk(" --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded,
1da177e4 LT	227	conf->raid_disks);
	228
	229	for (i = 0; i < conf->raid_disks; i++) {
	230	char b[BDEVNAME_SIZE];
	231	tmp = conf->multipaths + i;
	232	if (tmp->rdev)
	233	printk(" disk%d, o:%d, dev:%s\n",
b2d444d7	234	i,!test_bit(Faulty, &tmp->rdev->flags),
1da177e4 LT	235	bdevname(tmp->rdev->bdev,b));
	236	}
	237	}
	238
fd01b88c	239	static int multipath_add_disk(struct mddev mddev, struct md_rdev rdev)
1da177e4	240	{
69724e28	241	struct mpconf *conf = mddev->private;
352d768b	242	struct request_queue *q;
199050ea	243	int err = -EEXIST;
1da177e4 LT	244	int path;
1da177e4 LT	245	struct multipath_info *p;
6c2fce2e NB	246	int first = 0;
	247	int last = mddev->raid_disks - 1;
	248
	249	if (rdev->raid_disk >= 0)
	250	first = last = rdev->raid_disk;
1da177e4 LT	251
	252	print_multipath_conf(conf);
	253
6c2fce2e	254	for (path = first; path <= last; path++)
1da177e4	255	if ((p=conf->multipaths+path)->rdev == NULL) {
352d768b	256	q = rdev->bdev->bd_disk->queue;
8f6c2e4b MP	257	disk_stack_limits(mddev->gendisk, rdev->bdev,
8f6c2e4b MP	258	rdev->data_offset << 9);
1da177e4	259
6f8d0c77	260	spin_lock_irq(&conf->device_lock);
750a8f3e	261	mddev->degraded--;
1da177e4	262	rdev->raid_disk = path;
b2d444d7	263	set_bit(In_sync, &rdev->flags);
6f8d0c77	264	spin_unlock_irq(&conf->device_lock);
d6065f7b	265	rcu_assign_pointer(p->rdev, rdev);
199050ea	266	err = 0;
ac5e7113	267	md_integrity_add_rdev(rdev, mddev);
199050ea	268	break;
1da177e4 LT	269	}
	270
	271	print_multipath_conf(conf);
199050ea NB	272
199050ea NB	273	return err;
1da177e4 LT	274	}
1da177e4 LT	275
b8321b68	276	static int multipath_remove_disk(struct mddev mddev, struct md_rdev rdev)
1da177e4	277	{
69724e28	278	struct mpconf *conf = mddev->private;
1da177e4	279	int err = 0;
b8321b68	280	int number = rdev->raid_disk;
1da177e4 LT	281	struct multipath_info *p = conf->multipaths + number;
	282
	283	print_multipath_conf(conf);
	284
b8321b68	285	if (rdev == p->rdev) {
b2d444d7	286	if (test_bit(In_sync, &rdev->flags) \|\|
1da177e4	287	atomic_read(&rdev->nr_pending)) {
dfc70645 N	288	printk(KERN_ERR "hot-remove-disk, slot %d is identified"
dfc70645 N	289	" but is still operational!\n", number);
1da177e4 LT	290	err = -EBUSY;
	291	goto abort;
	292	}
	293	p->rdev = NULL;
fbd568a3	294	synchronize_rcu();
1da177e4 LT	295	if (atomic_read(&rdev->nr_pending)) {
	296	/* lost the race, try later */
	297	err = -EBUSY;
	298	p->rdev = rdev;
ac5e7113	299	goto abort;
1da177e4	300	}
a91a2785	301	err = md_integrity_register(mddev);
1da177e4 LT	302	}
	303	abort:
	304
	305	print_multipath_conf(conf);
	306	return err;
	307	}
	308
1da177e4 LT	309	/*
	310	* This is a kernel thread which:
	311	*
	312	* 1. Retries failed read operations on working multipaths.
	313	* 2. Updates the raid superblock when problems encounter.
	314	* 3. Performs writes following reads for array syncronising.
	315	*/
	316
4ed8731d	317	static void multipathd(struct md_thread *thread)
1da177e4	318	{
4ed8731d	319	struct mddev *mddev = thread->mddev;
1da177e4 LT	320	struct multipath_bh *mp_bh;
	321	struct bio *bio;
	322	unsigned long flags;
69724e28	323	struct mpconf *conf = mddev->private;
1da177e4 LT	324	struct list_head *head = &conf->retry_list;
	325
	326	md_check_recovery(mddev);
	327	for (;;) {
	328	char b[BDEVNAME_SIZE];
	329	spin_lock_irqsave(&conf->device_lock, flags);
	330	if (list_empty(head))
	331	break;
	332	mp_bh = list_entry(head->prev, struct multipath_bh, retry_list);
	333	list_del(head->prev);
	334	spin_unlock_irqrestore(&conf->device_lock, flags);
	335
	336	bio = &mp_bh->bio;
4f024f37	337	bio->bi_iter.bi_sector = mp_bh->master_bio->bi_iter.bi_sector;
f72ffdd6	338
1da177e4 LT	339	if ((mp_bh->path = multipath_map (conf))<0) {
	340	printk(KERN_ALERT "multipath: %s: unrecoverable IO read"
	341	" error for block %llu\n",
	342	bdevname(bio->bi_bdev,b),
4f024f37	343	(unsigned long long)bio->bi_iter.bi_sector);
1da177e4 LT	344	multipath_end_bh_io(mp_bh, -EIO);
	345	} else {
	346	printk(KERN_ERR "multipath: %s: redirecting sector %llu"
	347	" to another IO path\n",
	348	bdevname(bio->bi_bdev,b),
4f024f37	349	(unsigned long long)bio->bi_iter.bi_sector);
1da177e4	350	bio = (mp_bh->master_bio);
4f024f37 KO	351	bio->bi_iter.bi_sector +=
4f024f37 KO	352	conf->multipaths[mp_bh->path].rdev->data_offset;
1da177e4	353	bio->bi_bdev = conf->multipaths[mp_bh->path].rdev->bdev;
7b6d91da	354	bio->bi_rw \|= REQ_FAILFAST_TRANSPORT;
1da177e4 LT	355	bio->bi_end_io = multipath_end_request;
	356	bio->bi_private = mp_bh;
	357	generic_make_request(bio);
	358	}
	359	}
	360	spin_unlock_irqrestore(&conf->device_lock, flags);
	361	}
	362
fd01b88c	363	static sector_t multipath_size(struct mddev *mddev, sector_t sectors, int raid_disks)
80c3a6ce DW	364	{
	365	WARN_ONCE(sectors \|\| raid_disks,
	366	"%s does not support generic reshape\n", __func__);
	367
	368	return mddev->dev_sectors;
	369	}
	370
fd01b88c	371	static int multipath_run (struct mddev *mddev)
1da177e4	372	{
69724e28	373	struct mpconf *conf;
1da177e4 LT	374	int disk_idx;
1da177e4 LT	375	struct multipath_info *disk;
3cb03002	376	struct md_rdev *rdev;
92f861a7	377	int working_disks;
1da177e4	378
0894cc30 AN	379	if (md_check_no_bitmap(mddev))
	380	return -EINVAL;
	381
1da177e4 LT	382	if (mddev->level != LEVEL_MULTIPATH) {
	383	printk("multipath: %s: raid level not set to multipath IO (%d)\n",
	384	mdname(mddev), mddev->level);
	385	goto out;
	386	}
	387	/*
	388	* copy the already verified devices into our private MULTIPATH
	389	* bookkeeping area. [whatever we allocate in multipath_run(),
afa0f557	390	* should be freed in multipath_free()]
1da177e4 LT	391	*/
1da177e4 LT	392
69724e28	393	conf = kzalloc(sizeof(struct mpconf), GFP_KERNEL);
1da177e4 LT	394	mddev->private = conf;
1da177e4 LT	395	if (!conf) {
f72ffdd6	396	printk(KERN_ERR
1da177e4 LT	397	"multipath: couldn't allocate memory for %s\n",
	398	mdname(mddev));
	399	goto out;
	400	}
1da177e4	401
9ffae0cf	402	conf->multipaths = kzalloc(sizeof(struct multipath_info)*mddev->raid_disks,
1da177e4 LT	403	GFP_KERNEL);
1da177e4 LT	404	if (!conf->multipaths) {
f72ffdd6	405	printk(KERN_ERR
1da177e4 LT	406	"multipath: couldn't allocate memory for %s\n",
	407	mdname(mddev));
	408	goto out_free_conf;
	409	}
1da177e4	410
92f861a7	411	working_disks = 0;
dafb20fa	412	rdev_for_each(rdev, mddev) {
1da177e4 LT	413	disk_idx = rdev->raid_disk;
	414	if (disk_idx < 0 \|\|
	415	disk_idx >= mddev->raid_disks)
	416	continue;
	417
	418	disk = conf->multipaths + disk_idx;
	419	disk->rdev = rdev;
8f6c2e4b MP	420	disk_stack_limits(mddev->gendisk, rdev->bdev,
8f6c2e4b MP	421	rdev->data_offset << 9);
1da177e4	422
b2d444d7	423	if (!test_bit(Faulty, &rdev->flags))
92f861a7	424	working_disks++;
1da177e4 LT	425	}
	426
	427	conf->raid_disks = mddev->raid_disks;
1da177e4 LT	428	conf->mddev = mddev;
	429	spin_lock_init(&conf->device_lock);
	430	INIT_LIST_HEAD(&conf->retry_list);
	431
92f861a7	432	if (!working_disks) {
1da177e4 LT	433	printk(KERN_ERR "multipath: no operational IO paths for %s\n",
	434	mdname(mddev));
	435	goto out_free_conf;
	436	}
92f861a7	437	mddev->degraded = conf->raid_disks - working_disks;
1da177e4	438
bbba809e	439	conf->pool = mempool_create_kmalloc_pool(NR_RESERVED_BUFS,
26b6e051	440	sizeof(struct multipath_bh));
1da177e4	441	if (conf->pool == NULL) {
f72ffdd6	442	printk(KERN_ERR
1da177e4 LT	443	"multipath: couldn't allocate memory for %s\n",
	444	mdname(mddev));
	445	goto out_free_conf;
	446	}
	447
	448	{
0232605d N	449	mddev->thread = md_register_thread(multipathd, mddev,
0232605d N	450	"multipath");
1da177e4 LT	451	if (!mddev->thread) {
	452	printk(KERN_ERR "multipath: couldn't allocate thread"
	453	" for %s\n", mdname(mddev));
	454	goto out_free_conf;
	455	}
	456	}
	457
f72ffdd6	458	printk(KERN_INFO
1da177e4	459	"multipath: array %s active with %d out of %d IO paths\n",
92f861a7 N	460	mdname(mddev), conf->raid_disks - mddev->degraded,
92f861a7 N	461	mddev->raid_disks);
1da177e4 LT	462	/*
	463	* Ok, everything is just fine now
	464	*/
1f403624	465	md_set_array_sectors(mddev, multipath_size(mddev, 0, 0));
7a5febe9	466
a91a2785 MP	467	if (md_integrity_register(mddev))
	468	goto out_free_conf;
	469
1da177e4 LT	470	return 0;
	471
	472	out_free_conf:
	473	if (conf->pool)
	474	mempool_destroy(conf->pool);
990a8baf	475	kfree(conf->multipaths);
1da177e4 LT	476	kfree(conf);
	477	mddev->private = NULL;
	478	out:
	479	return -EIO;
	480	}
	481
afa0f557	482	static void multipath_free(struct mddev mddev, void priv)
1da177e4	483	{
afa0f557	484	struct mpconf *conf = priv;
1da177e4	485
1da177e4 LT	486	mempool_destroy(conf->pool);
	487	kfree(conf->multipaths);
	488	kfree(conf);
1da177e4 LT	489	}
1da177e4 LT	490
84fc4b56	491	static struct md_personality multipath_personality =
1da177e4 LT	492	{
1da177e4 LT	493	.name = "multipath",
2604b703	494	.level = LEVEL_MULTIPATH,
1da177e4 LT	495	.owner = THIS_MODULE,
	496	.make_request = multipath_make_request,
	497	.run = multipath_run,
afa0f557	498	.free = multipath_free,
1da177e4 LT	499	.status = multipath_status,
	500	.error_handler = multipath_error,
	501	.hot_add_disk = multipath_add_disk,
	502	.hot_remove_disk= multipath_remove_disk,
80c3a6ce	503	.size = multipath_size,
5c675f83	504	.congested = multipath_congested,
1da177e4 LT	505	};
	506
	507	static int __init multipath_init (void)
	508	{
2604b703	509	return register_md_personality (&multipath_personality);
1da177e4 LT	510	}
	511
	512	static void __exit multipath_exit (void)
	513	{
2604b703	514	unregister_md_personality (&multipath_personality);
1da177e4 LT	515	}
	516
	517	module_init(multipath_init);
	518	module_exit(multipath_exit);
	519	MODULE_LICENSE("GPL");
0efb9e61	520	MODULE_DESCRIPTION("simple multi-path personality for MD");
1da177e4	521	MODULE_ALIAS("md-personality-7"); /* MULTIPATH */
d9d166c2	522	MODULE_ALIAS("md-multipath");
2604b703	523	MODULE_ALIAS("md-level--4");