dm-mpath.c 48.9 KB
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/*
 * Copyright (C) 2003 Sistina Software Limited.
 * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
 *
 * This file is released under the GPL.
 */

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#include <linux/device-mapper.h>

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#include "dm-rq.h"
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#include "dm-bio-record.h"
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#include "dm-path-selector.h"
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#include "dm-uevent.h"
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#include <linux/blkdev.h>
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#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/mempool.h>
#include <linux/module.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/workqueue.h>
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#include <linux/delay.h>
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#include <scsi/scsi_dh.h>
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#include <linux/atomic.h>
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#include <linux/blk-mq.h>
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#define DM_MSG_PREFIX "multipath"
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#define DM_PG_INIT_DELAY_MSECS 2000
#define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1)
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/* Path properties */
struct pgpath {
	struct list_head list;

	struct priority_group *pg;	/* Owning PG */
	unsigned fail_count;		/* Cumulative failure count */

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	struct dm_path path;
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	struct delayed_work activate_path;
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	bool is_active:1;		/* Path status */
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};

#define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)

/*
 * Paths are grouped into Priority Groups and numbered from 1 upwards.
 * Each has a path selector which controls which path gets used.
 */
struct priority_group {
	struct list_head list;

	struct multipath *m;		/* Owning multipath instance */
	struct path_selector ps;

	unsigned pg_num;		/* Reference number */
	unsigned nr_pgpaths;		/* Number of paths in PG */
	struct list_head pgpaths;
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	bool bypassed:1;		/* Temporarily bypass this PG? */
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};

/* Multipath context */
struct multipath {
	struct list_head list;
	struct dm_target *ti;

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	const char *hw_handler_name;
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	char *hw_handler_params;
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	spinlock_t lock;

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	unsigned nr_priority_groups;
	struct list_head priority_groups;
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	wait_queue_head_t pg_init_wait;	/* Wait for pg_init completion */

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	struct pgpath *current_pgpath;
	struct priority_group *current_pg;
	struct priority_group *next_pg;	/* Switch to this PG if set */

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	unsigned long flags;		/* Multipath state flags */
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	unsigned pg_init_retries;	/* Number of times to retry pg_init */
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	unsigned pg_init_delay_msecs;	/* Number of msecs before pg_init retry */
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	atomic_t nr_valid_paths;	/* Total number of usable paths */
	atomic_t pg_init_in_progress;	/* Only one pg_init allowed at once */
	atomic_t pg_init_count;		/* Number of times pg_init called */

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	enum dm_queue_mode queue_mode;
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	struct mutex work_mutex;
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	struct work_struct trigger_event;
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	struct work_struct process_queued_bios;
	struct bio_list queued_bios;
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};

/*
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 * Context information attached to each io we process.
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 */
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struct dm_mpath_io {
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	struct pgpath *pgpath;
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	size_t nr_bytes;
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};

typedef int (*action_fn) (struct pgpath *pgpath);

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static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
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static void trigger_event(struct work_struct *work);
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static void activate_or_offline_path(struct pgpath *pgpath);
static void activate_path_work(struct work_struct *work);
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static void process_queued_bios(struct work_struct *work);
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/*-----------------------------------------------
 * Multipath state flags.
 *-----------------------------------------------*/

#define MPATHF_QUEUE_IO 0			/* Must we queue all I/O? */
#define MPATHF_QUEUE_IF_NO_PATH 1		/* Queue I/O if last path fails? */
#define MPATHF_SAVED_QUEUE_IF_NO_PATH 2		/* Saved state during suspension */
#define MPATHF_RETAIN_ATTACHED_HW_HANDLER 3	/* If there's already a hw_handler present, don't change it. */
#define MPATHF_PG_INIT_DISABLED 4		/* pg_init is not currently allowed */
#define MPATHF_PG_INIT_REQUIRED 5		/* pg_init needs calling? */
#define MPATHF_PG_INIT_DELAY_RETRY 6		/* Delay pg_init retry? */
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/*-----------------------------------------------
 * Allocation routines
 *-----------------------------------------------*/

static struct pgpath *alloc_pgpath(void)
{
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	struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
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	if (pgpath) {
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		pgpath->is_active = true;
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		INIT_DELAYED_WORK(&pgpath->activate_path, activate_path_work);
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	}
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	return pgpath;
}

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static void free_pgpath(struct pgpath *pgpath)
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{
	kfree(pgpath);
}

static struct priority_group *alloc_priority_group(void)
{
	struct priority_group *pg;

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	pg = kzalloc(sizeof(*pg), GFP_KERNEL);
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	if (pg)
		INIT_LIST_HEAD(&pg->pgpaths);
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	return pg;
}

static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
{
	struct pgpath *pgpath, *tmp;

	list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
		list_del(&pgpath->list);
		dm_put_device(ti, pgpath->path.dev);
		free_pgpath(pgpath);
	}
}

static void free_priority_group(struct priority_group *pg,
				struct dm_target *ti)
{
	struct path_selector *ps = &pg->ps;

	if (ps->type) {
		ps->type->destroy(ps);
		dm_put_path_selector(ps->type);
	}

	free_pgpaths(&pg->pgpaths, ti);
	kfree(pg);
}

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static struct multipath *alloc_multipath(struct dm_target *ti)
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{
	struct multipath *m;

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	m = kzalloc(sizeof(*m), GFP_KERNEL);
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	if (m) {
		INIT_LIST_HEAD(&m->priority_groups);
		spin_lock_init(&m->lock);
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		set_bit(MPATHF_QUEUE_IO, &m->flags);
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		atomic_set(&m->nr_valid_paths, 0);
		atomic_set(&m->pg_init_in_progress, 0);
		atomic_set(&m->pg_init_count, 0);
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		m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
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		INIT_WORK(&m->trigger_event, trigger_event);
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		init_waitqueue_head(&m->pg_init_wait);
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		mutex_init(&m->work_mutex);
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		m->queue_mode = DM_TYPE_NONE;
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		m->ti = ti;
		ti->private = m;
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	}

	return m;
}

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static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m)
{
	if (m->queue_mode == DM_TYPE_NONE) {
		/*
		 * Default to request-based.
		 */
		if (dm_use_blk_mq(dm_table_get_md(ti->table)))
			m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
		else
			m->queue_mode = DM_TYPE_REQUEST_BASED;
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	} else if (m->queue_mode == DM_TYPE_BIO_BASED) {
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		INIT_WORK(&m->process_queued_bios, process_queued_bios);
		/*
		 * bio-based doesn't support any direct scsi_dh management;
		 * it just discovers if a scsi_dh is attached.
		 */
		set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
	}

	dm_table_set_type(ti->table, m->queue_mode);

	return 0;
}

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static void free_multipath(struct multipath *m)
{
	struct priority_group *pg, *tmp;

	list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
		list_del(&pg->list);
		free_priority_group(pg, m->ti);
	}

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	kfree(m->hw_handler_name);
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	kfree(m->hw_handler_params);
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	kfree(m);
}

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static struct dm_mpath_io *get_mpio(union map_info *info)
{
	return info->ptr;
}

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static size_t multipath_per_bio_data_size(void)
{
	return sizeof(struct dm_mpath_io) + sizeof(struct dm_bio_details);
}

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static struct dm_mpath_io *get_mpio_from_bio(struct bio *bio)
{
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	return dm_per_bio_data(bio, multipath_per_bio_data_size());
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}

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static struct dm_bio_details *get_bio_details_from_mpio(struct dm_mpath_io *mpio)
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{
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	/* dm_bio_details is immediately after the dm_mpath_io in bio's per-bio-data */
	void *bio_details = mpio + 1;
	return bio_details;
}

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static void multipath_init_per_bio_data(struct bio *bio, struct dm_mpath_io **mpio_p)
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{
	struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
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	struct dm_bio_details *bio_details = get_bio_details_from_mpio(mpio);
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	mpio->nr_bytes = bio->bi_iter.bi_size;
	mpio->pgpath = NULL;
	*mpio_p = mpio;
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	dm_bio_record(bio_details, bio);
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}

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/*-----------------------------------------------
 * Path selection
 *-----------------------------------------------*/

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static int __pg_init_all_paths(struct multipath *m)
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{
	struct pgpath *pgpath;
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	unsigned long pg_init_delay = 0;
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	lockdep_assert_held(&m->lock);

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	if (atomic_read(&m->pg_init_in_progress) || test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
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		return 0;
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	atomic_inc(&m->pg_init_count);
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	clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
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	/* Check here to reset pg_init_required */
	if (!m->current_pg)
		return 0;

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	if (test_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags))
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		pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
						 m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
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	list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
		/* Skip failed paths */
		if (!pgpath->is_active)
			continue;
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		if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
				       pg_init_delay))
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			atomic_inc(&m->pg_init_in_progress);
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	}
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	return atomic_read(&m->pg_init_in_progress);
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}

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static int pg_init_all_paths(struct multipath *m)
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{
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	int ret;
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	unsigned long flags;

	spin_lock_irqsave(&m->lock, flags);
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	ret = __pg_init_all_paths(m);
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	spin_unlock_irqrestore(&m->lock, flags);
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	return ret;
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}

static void __switch_pg(struct multipath *m, struct priority_group *pg)
{
	m->current_pg = pg;
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	/* Must we initialise the PG first, and queue I/O till it's ready? */
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	if (m->hw_handler_name) {
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		set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
		set_bit(MPATHF_QUEUE_IO, &m->flags);
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	} else {
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		clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
		clear_bit(MPATHF_QUEUE_IO, &m->flags);
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	}
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	atomic_set(&m->pg_init_count, 0);
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}

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static struct pgpath *choose_path_in_pg(struct multipath *m,
					struct priority_group *pg,
					size_t nr_bytes)
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{
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	unsigned long flags;
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	struct dm_path *path;
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	struct pgpath *pgpath;
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	path = pg->ps.type->select_path(&pg->ps, nr_bytes);
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	if (!path)
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		return ERR_PTR(-ENXIO);
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	pgpath = path_to_pgpath(path);
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	if (unlikely(READ_ONCE(m->current_pg) != pg)) {
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		/* Only update current_pgpath if pg changed */
		spin_lock_irqsave(&m->lock, flags);
		m->current_pgpath = pgpath;
		__switch_pg(m, pg);
		spin_unlock_irqrestore(&m->lock, flags);
	}
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	return pgpath;
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}

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static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes)
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{
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	unsigned long flags;
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	struct priority_group *pg;
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	struct pgpath *pgpath;
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	unsigned bypassed = 1;
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	if (!atomic_read(&m->nr_valid_paths)) {
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		clear_bit(MPATHF_QUEUE_IO, &m->flags);
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		goto failed;
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	}
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	/* Were we instructed to switch PG? */
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	if (READ_ONCE(m->next_pg)) {
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		spin_lock_irqsave(&m->lock, flags);
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		pg = m->next_pg;
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		if (!pg) {
			spin_unlock_irqrestore(&m->lock, flags);
			goto check_current_pg;
		}
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		m->next_pg = NULL;
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		spin_unlock_irqrestore(&m->lock, flags);
		pgpath = choose_path_in_pg(m, pg, nr_bytes);
		if (!IS_ERR_OR_NULL(pgpath))
			return pgpath;
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	}

	/* Don't change PG until it has no remaining paths */
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check_current_pg:
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	pg = READ_ONCE(m->current_pg);
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	if (pg) {
		pgpath = choose_path_in_pg(m, pg, nr_bytes);
		if (!IS_ERR_OR_NULL(pgpath))
			return pgpath;
	}
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	/*
	 * Loop through priority groups until we find a valid path.
	 * First time we skip PGs marked 'bypassed'.
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	 * Second time we only try the ones we skipped, but set
	 * pg_init_delay_retry so we do not hammer controllers.
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	 */
	do {
		list_for_each_entry(pg, &m->priority_groups, list) {
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			if (pg->bypassed == !!bypassed)
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				continue;
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			pgpath = choose_path_in_pg(m, pg, nr_bytes);
			if (!IS_ERR_OR_NULL(pgpath)) {
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				if (!bypassed)
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					set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
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				return pgpath;
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			}
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		}
	} while (bypassed--);

failed:
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	spin_lock_irqsave(&m->lock, flags);
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	m->current_pgpath = NULL;
	m->current_pg = NULL;
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	spin_unlock_irqrestore(&m->lock, flags);

	return NULL;
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}

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/*
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 * dm_report_EIO() is a macro instead of a function to make pr_debug()
 * report the function name and line number of the function from which
 * it has been invoked.
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 */
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#define dm_report_EIO(m)						\
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do {									\
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	struct mapped_device *md = dm_table_get_md((m)->ti->table);	\
									\
	pr_debug("%s: returning EIO; QIFNP = %d; SQIFNP = %d; DNFS = %d\n", \
		 dm_device_name(md),					\
		 test_bit(MPATHF_QUEUE_IF_NO_PATH, &(m)->flags),	\
		 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &(m)->flags),	\
		 dm_noflush_suspending((m)->ti));			\
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} while (0)
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/*
 * Check whether bios must be queued in the device-mapper core rather
 * than here in the target.
 *
 * If MPATHF_QUEUE_IF_NO_PATH and MPATHF_SAVED_QUEUE_IF_NO_PATH hold
 * the same value then we are not between multipath_presuspend()
 * and multipath_resume() calls and we have no need to check
 * for the DMF_NOFLUSH_SUSPENDING flag.
 */
static bool __must_push_back(struct multipath *m, unsigned long flags)
{
	return ((test_bit(MPATHF_QUEUE_IF_NO_PATH, &flags) !=
		 test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &flags)) &&
		dm_noflush_suspending(m->ti));
}

/*
 * Following functions use READ_ONCE to get atomic access to
 * all m->flags to avoid taking spinlock
 */
static bool must_push_back_rq(struct multipath *m)
{
	unsigned long flags = READ_ONCE(m->flags);
	return test_bit(MPATHF_QUEUE_IF_NO_PATH, &flags) || __must_push_back(m, flags);
}

static bool must_push_back_bio(struct multipath *m)
{
	unsigned long flags = READ_ONCE(m->flags);
	return __must_push_back(m, flags);
}

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/*
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 * Map cloned requests (request-based multipath)
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 */
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static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
				   union map_info *map_context,
				   struct request **__clone)
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{
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	struct multipath *m = ti->private;
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	size_t nr_bytes = blk_rq_bytes(rq);
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	struct pgpath *pgpath;
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	struct block_device *bdev;
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	struct dm_mpath_io *mpio = get_mpio(map_context);
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	struct request_queue *q;
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	struct request *clone;
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	/* Do we need to select a new pgpath? */
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	pgpath = READ_ONCE(m->current_pgpath);
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	if (!pgpath || !test_bit(MPATHF_QUEUE_IO, &m->flags))
		pgpath = choose_pgpath(m, nr_bytes);
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	if (!pgpath) {
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		if (must_push_back_rq(m))
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			return DM_MAPIO_DELAY_REQUEUE;
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		dm_report_EIO(m);	/* Failed */
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		return DM_MAPIO_KILL;
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	} else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
		   test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
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		if (pg_init_all_paths(m))
			return DM_MAPIO_DELAY_REQUEUE;
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		return DM_MAPIO_REQUEUE;
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	}
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	mpio->pgpath = pgpath;
	mpio->nr_bytes = nr_bytes;

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	bdev = pgpath->path.dev->bdev;
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	q = bdev_get_queue(bdev);
	clone = blk_get_request(q, rq->cmd_flags | REQ_NOMERGE, GFP_ATOMIC);
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	if (IS_ERR(clone)) {
		/* EBUSY, ENODEV or EWOULDBLOCK: requeue */
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		bool queue_dying = blk_queue_dying(q);
		if (queue_dying) {
			atomic_inc(&m->pg_init_in_progress);
			activate_or_offline_path(pgpath);
		}
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		return DM_MAPIO_DELAY_REQUEUE;
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	}
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	clone->bio = clone->biotail = NULL;
	clone->rq_disk = bdev->bd_disk;
	clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
	*__clone = clone;
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	if (pgpath->pg->ps.type->start_io)
		pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
					      &pgpath->path,
					      nr_bytes);
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	return DM_MAPIO_REMAPPED;
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}

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static void multipath_release_clone(struct request *clone)
{
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	blk_put_request(clone);
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}

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/*
 * Map cloned bios (bio-based multipath)
 */
static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_mpath_io *mpio)
{
	struct pgpath *pgpath;
	unsigned long flags;
	bool queue_io;

	/* Do we need to select a new pgpath? */
560
	pgpath = READ_ONCE(m->current_pgpath);
561 562
	queue_io = test_bit(MPATHF_QUEUE_IO, &m->flags);
	if (!pgpath || !queue_io)
563
		pgpath = choose_pgpath(m, mpio->nr_bytes);
564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579

	if ((pgpath && queue_io) ||
	    (!pgpath && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))) {
		/* Queue for the daemon to resubmit */
		spin_lock_irqsave(&m->lock, flags);
		bio_list_add(&m->queued_bios, bio);
		spin_unlock_irqrestore(&m->lock, flags);
		/* PG_INIT_REQUIRED cannot be set without QUEUE_IO */
		if (queue_io || test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
			pg_init_all_paths(m);
		else if (!queue_io)
			queue_work(kmultipathd, &m->process_queued_bios);
		return DM_MAPIO_SUBMITTED;
	}

	if (!pgpath) {
580
		if (must_push_back_bio(m))
581
			return DM_MAPIO_REQUEUE;
582
		dm_report_EIO(m);
583
		return DM_MAPIO_KILL;
584 585 586 587
	}

	mpio->pgpath = pgpath;

588
	bio->bi_status = 0;
589
	bio_set_dev(bio, pgpath->path.dev->bdev);
J
Jens Axboe 已提交
590
	bio->bi_opf |= REQ_FAILFAST_TRANSPORT;
591 592 593 594

	if (pgpath->pg->ps.type->start_io)
		pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
					      &pgpath->path,
595
					      mpio->nr_bytes);
596 597 598 599 600 601
	return DM_MAPIO_REMAPPED;
}

static int multipath_map_bio(struct dm_target *ti, struct bio *bio)
{
	struct multipath *m = ti->private;
602 603
	struct dm_mpath_io *mpio = NULL;

604
	multipath_init_per_bio_data(bio, &mpio);
605 606 607
	return __multipath_map_bio(m, bio, mpio);
}

608
static void process_queued_io_list(struct multipath *m)
609
{
610 611 612
	if (m->queue_mode == DM_TYPE_MQ_REQUEST_BASED)
		dm_mq_kick_requeue_list(dm_table_get_md(m->ti->table));
	else if (m->queue_mode == DM_TYPE_BIO_BASED)
613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641
		queue_work(kmultipathd, &m->process_queued_bios);
}

static void process_queued_bios(struct work_struct *work)
{
	int r;
	unsigned long flags;
	struct bio *bio;
	struct bio_list bios;
	struct blk_plug plug;
	struct multipath *m =
		container_of(work, struct multipath, process_queued_bios);

	bio_list_init(&bios);

	spin_lock_irqsave(&m->lock, flags);

	if (bio_list_empty(&m->queued_bios)) {
		spin_unlock_irqrestore(&m->lock, flags);
		return;
	}

	bio_list_merge(&bios, &m->queued_bios);
	bio_list_init(&m->queued_bios);

	spin_unlock_irqrestore(&m->lock, flags);

	blk_start_plug(&plug);
	while ((bio = bio_list_pop(&bios))) {
642 643 644
		struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
		dm_bio_restore(get_bio_details_from_mpio(mpio), bio);
		r = __multipath_map_bio(m, bio, mpio);
645 646
		switch (r) {
		case DM_MAPIO_KILL:
647 648
			bio->bi_status = BLK_STS_IOERR;
			bio_endio(bio);
649
			break;
650
		case DM_MAPIO_REQUEUE:
651
			bio->bi_status = BLK_STS_DM_REQUEUE;
652
			bio_endio(bio);
653 654
			break;
		case DM_MAPIO_REMAPPED:
655
			generic_make_request(bio);
656
			break;
657 658 659 660
		case 0:
			break;
		default:
			WARN_ONCE(true, "__multipath_map_bio() returned %d\n", r);
661
		}
662 663 664 665
	}
	blk_finish_plug(&plug);
}

L
Linus Torvalds 已提交
666 667 668
/*
 * If we run out of usable paths, should we queue I/O or error it?
 */
669 670
static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
			    bool save_old_value)
L
Linus Torvalds 已提交
671 672 673 674
{
	unsigned long flags;

	spin_lock_irqsave(&m->lock, flags);
L
Lukas Wunner 已提交
675 676 677
	assign_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags,
		   (save_old_value && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) ||
		   (!save_old_value && queue_if_no_path));
678
	assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags, queue_if_no_path);
L
Linus Torvalds 已提交
679 680
	spin_unlock_irqrestore(&m->lock, flags);

681
	if (!queue_if_no_path) {
682
		dm_table_run_md_queue_async(m->ti->table);
683
		process_queued_io_list(m);
684
	}
685

L
Linus Torvalds 已提交
686 687 688 689 690 691 692
	return 0;
}

/*
 * An event is triggered whenever a path is taken out of use.
 * Includes path failure and PG bypass.
 */
D
David Howells 已提交
693
static void trigger_event(struct work_struct *work)
L
Linus Torvalds 已提交
694
{
D
David Howells 已提交
695 696
	struct multipath *m =
		container_of(work, struct multipath, trigger_event);
L
Linus Torvalds 已提交
697 698 699 700 701 702 703 704 705 706 707 708 709 710

	dm_table_event(m->ti->table);
}

/*-----------------------------------------------------------------
 * Constructor/argument parsing:
 * <#multipath feature args> [<arg>]*
 * <#hw_handler args> [hw_handler [<arg>]*]
 * <#priority groups>
 * <initial priority group>
 *     [<selector> <#selector args> [<arg>]*
 *      <#paths> <#per-path selector args>
 *         [<path> [<arg>]* ]+ ]+
 *---------------------------------------------------------------*/
711
static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
L
Linus Torvalds 已提交
712 713 714 715 716 717
			       struct dm_target *ti)
{
	int r;
	struct path_selector_type *pst;
	unsigned ps_argc;

E
Eric Biggers 已提交
718
	static const struct dm_arg _args[] = {
719
		{0, 1024, "invalid number of path selector args"},
L
Linus Torvalds 已提交
720 721
	};

722
	pst = dm_get_path_selector(dm_shift_arg(as));
L
Linus Torvalds 已提交
723
	if (!pst) {
724
		ti->error = "unknown path selector type";
L
Linus Torvalds 已提交
725 726 727
		return -EINVAL;
	}

728
	r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
729 730
	if (r) {
		dm_put_path_selector(pst);
L
Linus Torvalds 已提交
731
		return -EINVAL;
732
	}
L
Linus Torvalds 已提交
733 734 735 736

	r = pst->create(&pg->ps, ps_argc, as->argv);
	if (r) {
		dm_put_path_selector(pst);
737
		ti->error = "path selector constructor failed";
L
Linus Torvalds 已提交
738 739 740 741
		return r;
	}

	pg->ps.type = pst;
742
	dm_consume_args(as, ps_argc);
L
Linus Torvalds 已提交
743 744 745 746

	return 0;
}

747
static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
L
Linus Torvalds 已提交
748 749 750 751
			       struct dm_target *ti)
{
	int r;
	struct pgpath *p;
752
	struct multipath *m = ti->private;
753 754
	struct request_queue *q = NULL;
	const char *attached_handler_name;
L
Linus Torvalds 已提交
755 756 757

	/* we need at least a path arg */
	if (as->argc < 1) {
758
		ti->error = "no device given";
759
		return ERR_PTR(-EINVAL);
L
Linus Torvalds 已提交
760 761 762 763
	}

	p = alloc_pgpath();
	if (!p)
764
		return ERR_PTR(-ENOMEM);
L
Linus Torvalds 已提交
765

766
	r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
767
			  &p->path.dev);
L
Linus Torvalds 已提交
768
	if (r) {
769
		ti->error = "error getting device";
L
Linus Torvalds 已提交
770 771 772
		goto bad;
	}

773
	if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) || m->hw_handler_name)
774 775
		q = bdev_get_queue(p->path.dev->bdev);

776
	if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags)) {
777
retain:
778 779
		attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
		if (attached_handler_name) {
780 781 782 783 784 785 786 787 788
			/*
			 * Clear any hw_handler_params associated with a
			 * handler that isn't already attached.
			 */
			if (m->hw_handler_name && strcmp(attached_handler_name, m->hw_handler_name)) {
				kfree(m->hw_handler_params);
				m->hw_handler_params = NULL;
			}

789 790 791 792 793 794 795 796 797 798
			/*
			 * Reset hw_handler_name to match the attached handler
			 *
			 * NB. This modifies the table line to show the actual
			 * handler instead of the original table passed in.
			 */
			kfree(m->hw_handler_name);
			m->hw_handler_name = attached_handler_name;
		}
	}
799

800
	if (m->hw_handler_name) {
801 802
		r = scsi_dh_attach(q, m->hw_handler_name);
		if (r == -EBUSY) {
803
			char b[BDEVNAME_SIZE];
804

805 806 807 808
			printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
				bdevname(p->path.dev->bdev, b));
			goto retain;
		}
809
		if (r < 0) {
810
			ti->error = "error attaching hardware handler";
811 812 813
			dm_put_device(ti, p->path.dev);
			goto bad;
		}
814 815 816 817 818 819 820 821 822 823

		if (m->hw_handler_params) {
			r = scsi_dh_set_params(q, m->hw_handler_params);
			if (r < 0) {
				ti->error = "unable to set hardware "
							"handler parameters";
				dm_put_device(ti, p->path.dev);
				goto bad;
			}
		}
824 825
	}

L
Linus Torvalds 已提交
826 827 828 829 830 831 832 833 834 835
	r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
	if (r) {
		dm_put_device(ti, p->path.dev);
		goto bad;
	}

	return p;

 bad:
	free_pgpath(p);
836
	return ERR_PTR(r);
L
Linus Torvalds 已提交
837 838
}

839
static struct priority_group *parse_priority_group(struct dm_arg_set *as,
M
Micha³ Miros³aw 已提交
840
						   struct multipath *m)
L
Linus Torvalds 已提交
841
{
E
Eric Biggers 已提交
842
	static const struct dm_arg _args[] = {
843 844
		{1, 1024, "invalid number of paths"},
		{0, 1024, "invalid number of selector args"}
L
Linus Torvalds 已提交
845 846 847
	};

	int r;
848
	unsigned i, nr_selector_args, nr_args;
L
Linus Torvalds 已提交
849
	struct priority_group *pg;
M
Micha³ Miros³aw 已提交
850
	struct dm_target *ti = m->ti;
L
Linus Torvalds 已提交
851 852 853

	if (as->argc < 2) {
		as->argc = 0;
854 855
		ti->error = "not enough priority group arguments";
		return ERR_PTR(-EINVAL);
L
Linus Torvalds 已提交
856 857 858 859
	}

	pg = alloc_priority_group();
	if (!pg) {
860
		ti->error = "couldn't allocate priority group";
861
		return ERR_PTR(-ENOMEM);
L
Linus Torvalds 已提交
862 863 864 865 866 867 868 869 870 871
	}
	pg->m = m;

	r = parse_path_selector(as, pg, ti);
	if (r)
		goto bad;

	/*
	 * read the paths
	 */
872
	r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
L
Linus Torvalds 已提交
873 874 875
	if (r)
		goto bad;

876
	r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
L
Linus Torvalds 已提交
877 878 879
	if (r)
		goto bad;

880
	nr_args = 1 + nr_selector_args;
L
Linus Torvalds 已提交
881 882
	for (i = 0; i < pg->nr_pgpaths; i++) {
		struct pgpath *pgpath;
883
		struct dm_arg_set path_args;
L
Linus Torvalds 已提交
884

885
		if (as->argc < nr_args) {
886
			ti->error = "not enough path parameters";
887
			r = -EINVAL;
L
Linus Torvalds 已提交
888
			goto bad;
889
		}
L
Linus Torvalds 已提交
890

891
		path_args.argc = nr_args;
L
Linus Torvalds 已提交
892 893 894
		path_args.argv = as->argv;

		pgpath = parse_path(&path_args, &pg->ps, ti);
895 896
		if (IS_ERR(pgpath)) {
			r = PTR_ERR(pgpath);
L
Linus Torvalds 已提交
897
			goto bad;
898
		}
L
Linus Torvalds 已提交
899 900 901

		pgpath->pg = pg;
		list_add_tail(&pgpath->list, &pg->pgpaths);
902
		dm_consume_args(as, nr_args);
L
Linus Torvalds 已提交
903 904 905 906 907 908
	}

	return pg;

 bad:
	free_priority_group(pg, ti);
909
	return ERR_PTR(r);
L
Linus Torvalds 已提交
910 911
}

912
static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
L
Linus Torvalds 已提交
913 914
{
	unsigned hw_argc;
915
	int ret;
M
Micha³ Miros³aw 已提交
916
	struct dm_target *ti = m->ti;
L
Linus Torvalds 已提交
917

E
Eric Biggers 已提交
918
	static const struct dm_arg _args[] = {
919
		{0, 1024, "invalid number of hardware handler args"},
L
Linus Torvalds 已提交
920 921
	};

922
	if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
L
Linus Torvalds 已提交
923 924 925 926 927
		return -EINVAL;

	if (!hw_argc)
		return 0;

928
	if (m->queue_mode == DM_TYPE_BIO_BASED) {
929 930 931 932 933
		dm_consume_args(as, hw_argc);
		DMERR("bio-based multipath doesn't allow hardware handler args");
		return 0;
	}

934
	m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
935 936
	if (!m->hw_handler_name)
		return -EINVAL;
937

938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953
	if (hw_argc > 1) {
		char *p;
		int i, j, len = 4;

		for (i = 0; i <= hw_argc - 2; i++)
			len += strlen(as->argv[i]) + 1;
		p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
		if (!p) {
			ti->error = "memory allocation failed";
			ret = -ENOMEM;
			goto fail;
		}
		j = sprintf(p, "%d", hw_argc - 1);
		for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
			j = sprintf(p, "%s", as->argv[i]);
	}
954
	dm_consume_args(as, hw_argc - 1);
L
Linus Torvalds 已提交
955 956

	return 0;
957 958 959 960
fail:
	kfree(m->hw_handler_name);
	m->hw_handler_name = NULL;
	return ret;
L
Linus Torvalds 已提交
961 962
}

963
static int parse_features(struct dm_arg_set *as, struct multipath *m)
L
Linus Torvalds 已提交
964 965 966
{
	int r;
	unsigned argc;
M
Micha³ Miros³aw 已提交
967
	struct dm_target *ti = m->ti;
968
	const char *arg_name;
L
Linus Torvalds 已提交
969

E
Eric Biggers 已提交
970
	static const struct dm_arg _args[] = {
971
		{0, 8, "invalid number of feature args"},
D
Dave Wysochanski 已提交
972
		{1, 50, "pg_init_retries must be between 1 and 50"},
973
		{0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
L
Linus Torvalds 已提交
974 975
	};

976
	r = dm_read_arg_group(_args, as, &argc, &ti->error);
L
Linus Torvalds 已提交
977 978 979 980 981 982
	if (r)
		return -EINVAL;

	if (!argc)
		return 0;

D
Dave Wysochanski 已提交
983
	do {
984
		arg_name = dm_shift_arg(as);
D
Dave Wysochanski 已提交
985 986
		argc--;

987
		if (!strcasecmp(arg_name, "queue_if_no_path")) {
988
			r = queue_if_no_path(m, true, false);
D
Dave Wysochanski 已提交
989 990 991
			continue;
		}

992
		if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
993
			set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
994 995 996
			continue;
		}

997
		if (!strcasecmp(arg_name, "pg_init_retries") &&
D
Dave Wysochanski 已提交
998
		    (argc >= 1)) {
999
			r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
D
Dave Wysochanski 已提交
1000 1001 1002 1003
			argc--;
			continue;
		}

1004
		if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
1005
		    (argc >= 1)) {
1006
			r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
1007 1008 1009 1010
			argc--;
			continue;
		}

1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028
		if (!strcasecmp(arg_name, "queue_mode") &&
		    (argc >= 1)) {
			const char *queue_mode_name = dm_shift_arg(as);

			if (!strcasecmp(queue_mode_name, "bio"))
				m->queue_mode = DM_TYPE_BIO_BASED;
			else if (!strcasecmp(queue_mode_name, "rq"))
				m->queue_mode = DM_TYPE_REQUEST_BASED;
			else if (!strcasecmp(queue_mode_name, "mq"))
				m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
			else {
				ti->error = "Unknown 'queue_mode' requested";
				r = -EINVAL;
			}
			argc--;
			continue;
		}

L
Linus Torvalds 已提交
1029
		ti->error = "Unrecognised multipath feature request";
D
Dave Wysochanski 已提交
1030 1031 1032 1033
		r = -EINVAL;
	} while (argc && !r);

	return r;
L
Linus Torvalds 已提交
1034 1035
}

1036
static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
L
Linus Torvalds 已提交
1037
{
1038
	/* target arguments */
E
Eric Biggers 已提交
1039
	static const struct dm_arg _args[] = {
1040 1041
		{0, 1024, "invalid number of priority groups"},
		{0, 1024, "invalid initial priority group number"},
L
Linus Torvalds 已提交
1042 1043 1044 1045
	};

	int r;
	struct multipath *m;
1046
	struct dm_arg_set as;
L
Linus Torvalds 已提交
1047 1048 1049 1050 1051 1052
	unsigned pg_count = 0;
	unsigned next_pg_num;

	as.argc = argc;
	as.argv = argv;

1053
	m = alloc_multipath(ti);
L
Linus Torvalds 已提交
1054
	if (!m) {
1055
		ti->error = "can't allocate multipath";
L
Linus Torvalds 已提交
1056 1057 1058
		return -EINVAL;
	}

M
Micha³ Miros³aw 已提交
1059
	r = parse_features(&as, m);
L
Linus Torvalds 已提交
1060 1061 1062
	if (r)
		goto bad;

1063 1064 1065 1066
	r = alloc_multipath_stage2(ti, m);
	if (r)
		goto bad;

M
Micha³ Miros³aw 已提交
1067
	r = parse_hw_handler(&as, m);
L
Linus Torvalds 已提交
1068 1069 1070
	if (r)
		goto bad;

1071
	r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
L
Linus Torvalds 已提交
1072 1073 1074
	if (r)
		goto bad;

1075
	r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
L
Linus Torvalds 已提交
1076 1077 1078
	if (r)
		goto bad;

1079 1080 1081 1082 1083 1084 1085
	if ((!m->nr_priority_groups && next_pg_num) ||
	    (m->nr_priority_groups && !next_pg_num)) {
		ti->error = "invalid initial priority group";
		r = -EINVAL;
		goto bad;
	}

L
Linus Torvalds 已提交
1086 1087 1088
	/* parse the priority groups */
	while (as.argc) {
		struct priority_group *pg;
1089
		unsigned nr_valid_paths = atomic_read(&m->nr_valid_paths);
L
Linus Torvalds 已提交
1090

M
Micha³ Miros³aw 已提交
1091
		pg = parse_priority_group(&as, m);
1092 1093
		if (IS_ERR(pg)) {
			r = PTR_ERR(pg);
L
Linus Torvalds 已提交
1094 1095 1096
			goto bad;
		}

1097 1098 1099
		nr_valid_paths += pg->nr_pgpaths;
		atomic_set(&m->nr_valid_paths, nr_valid_paths);

L
Linus Torvalds 已提交
1100 1101 1102 1103 1104 1105 1106 1107
		list_add_tail(&pg->list, &m->priority_groups);
		pg_count++;
		pg->pg_num = pg_count;
		if (!--next_pg_num)
			m->next_pg = pg;
	}

	if (pg_count != m->nr_priority_groups) {
1108
		ti->error = "priority group count mismatch";
L
Linus Torvalds 已提交
1109 1110 1111 1112
		r = -EINVAL;
		goto bad;
	}

1113 1114
	ti->num_flush_bios = 1;
	ti->num_discard_bios = 1;
1115
	ti->num_write_same_bios = 1;
1116
	ti->num_write_zeroes_bios = 1;
1117
	if (m->queue_mode == DM_TYPE_BIO_BASED)
1118
		ti->per_io_data_size = multipath_per_bio_data_size();
1119
	else
1120
		ti->per_io_data_size = sizeof(struct dm_mpath_io);
M
Mikulas Patocka 已提交
1121

L
Linus Torvalds 已提交
1122 1123 1124 1125 1126 1127 1128
	return 0;

 bad:
	free_multipath(m);
	return r;
}

1129 1130
static void multipath_wait_for_pg_init_completion(struct multipath *m)
{
1131
	DEFINE_WAIT(wait);
1132 1133

	while (1) {
1134
		prepare_to_wait(&m->pg_init_wait, &wait, TASK_UNINTERRUPTIBLE);
1135

1136
		if (!atomic_read(&m->pg_init_in_progress))
1137 1138 1139 1140
			break;

		io_schedule();
	}
1141
	finish_wait(&m->pg_init_wait, &wait);
1142 1143 1144
}

static void flush_multipath_work(struct multipath *m)
L
Linus Torvalds 已提交
1145
{
1146 1147
	set_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
	smp_mb__after_atomic();
1148

1149
	flush_workqueue(kmpath_handlerd);
1150
	multipath_wait_for_pg_init_completion(m);
1151
	flush_workqueue(kmultipathd);
1152
	flush_work(&m->trigger_event);
1153

1154 1155
	clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
	smp_mb__after_atomic();
1156 1157 1158 1159 1160 1161
}

static void multipath_dtr(struct dm_target *ti)
{
	struct multipath *m = ti->private;

1162
	flush_multipath_work(m);
L
Linus Torvalds 已提交
1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175
	free_multipath(m);
}

/*
 * Take a path out of use.
 */
static int fail_path(struct pgpath *pgpath)
{
	unsigned long flags;
	struct multipath *m = pgpath->pg->m;

	spin_lock_irqsave(&m->lock, flags);

1176
	if (!pgpath->is_active)
L
Linus Torvalds 已提交
1177 1178
		goto out;

1179
	DMWARN("Failing path %s.", pgpath->path.dev->name);
L
Linus Torvalds 已提交
1180 1181

	pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
1182
	pgpath->is_active = false;
L
Linus Torvalds 已提交
1183 1184
	pgpath->fail_count++;

1185
	atomic_dec(&m->nr_valid_paths);
L
Linus Torvalds 已提交
1186 1187 1188 1189

	if (pgpath == m->current_pgpath)
		m->current_pgpath = NULL;

M
Mike Anderson 已提交
1190
	dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
1191
		       pgpath->path.dev->name, atomic_read(&m->nr_valid_paths));
M
Mike Anderson 已提交
1192

1193
	schedule_work(&m->trigger_event);
L
Linus Torvalds 已提交
1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205

out:
	spin_unlock_irqrestore(&m->lock, flags);

	return 0;
}

/*
 * Reinstate a previously-failed path
 */
static int reinstate_path(struct pgpath *pgpath)
{
1206
	int r = 0, run_queue = 0;
L
Linus Torvalds 已提交
1207 1208
	unsigned long flags;
	struct multipath *m = pgpath->pg->m;
1209
	unsigned nr_valid_paths;
L
Linus Torvalds 已提交
1210 1211 1212

	spin_lock_irqsave(&m->lock, flags);

1213
	if (pgpath->is_active)
L
Linus Torvalds 已提交
1214 1215
		goto out;

1216
	DMWARN("Reinstating path %s.", pgpath->path.dev->name);
L
Linus Torvalds 已提交
1217 1218 1219 1220 1221

	r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
	if (r)
		goto out;

1222
	pgpath->is_active = true;
L
Linus Torvalds 已提交
1223

1224 1225
	nr_valid_paths = atomic_inc_return(&m->nr_valid_paths);
	if (nr_valid_paths == 1) {
1226
		m->current_pgpath = NULL;
1227
		run_queue = 1;
1228
	} else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1229
		if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1230
			atomic_inc(&m->pg_init_in_progress);
1231
	}
L
Linus Torvalds 已提交
1232

M
Mike Anderson 已提交
1233
	dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1234
		       pgpath->path.dev->name, nr_valid_paths);
M
Mike Anderson 已提交
1235

1236
	schedule_work(&m->trigger_event);
L
Linus Torvalds 已提交
1237 1238 1239

out:
	spin_unlock_irqrestore(&m->lock, flags);
1240
	if (run_queue) {
1241
		dm_table_run_md_queue_async(m->ti->table);
1242
		process_queued_io_list(m);
1243
	}
L
Linus Torvalds 已提交
1244 1245 1246 1247 1248 1249 1250 1251 1252 1253

	return r;
}

/*
 * Fail or reinstate all paths that match the provided struct dm_dev.
 */
static int action_dev(struct multipath *m, struct dm_dev *dev,
		      action_fn action)
{
1254
	int r = -EINVAL;
L
Linus Torvalds 已提交
1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271
	struct pgpath *pgpath;
	struct priority_group *pg;

	list_for_each_entry(pg, &m->priority_groups, list) {
		list_for_each_entry(pgpath, &pg->pgpaths, list) {
			if (pgpath->path.dev == dev)
				r = action(pgpath);
		}
	}

	return r;
}

/*
 * Temporarily try to avoid having to use the specified PG
 */
static void bypass_pg(struct multipath *m, struct priority_group *pg,
1272
		      bool bypassed)
L
Linus Torvalds 已提交
1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283
{
	unsigned long flags;

	spin_lock_irqsave(&m->lock, flags);

	pg->bypassed = bypassed;
	m->current_pgpath = NULL;
	m->current_pg = NULL;

	spin_unlock_irqrestore(&m->lock, flags);

1284
	schedule_work(&m->trigger_event);
L
Linus Torvalds 已提交
1285 1286 1287 1288 1289 1290 1291 1292 1293 1294
}

/*
 * Switch to using the specified PG from the next I/O that gets mapped
 */
static int switch_pg_num(struct multipath *m, const char *pgstr)
{
	struct priority_group *pg;
	unsigned pgnum;
	unsigned long flags;
1295
	char dummy;
L
Linus Torvalds 已提交
1296

1297
	if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1298
	    !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
L
Linus Torvalds 已提交
1299 1300 1301 1302 1303 1304
		DMWARN("invalid PG number supplied to switch_pg_num");
		return -EINVAL;
	}

	spin_lock_irqsave(&m->lock, flags);
	list_for_each_entry(pg, &m->priority_groups, list) {
1305
		pg->bypassed = false;
L
Linus Torvalds 已提交
1306 1307 1308 1309 1310 1311 1312 1313 1314
		if (--pgnum)
			continue;

		m->current_pgpath = NULL;
		m->current_pg = NULL;
		m->next_pg = pg;
	}
	spin_unlock_irqrestore(&m->lock, flags);

1315
	schedule_work(&m->trigger_event);
L
Linus Torvalds 已提交
1316 1317 1318 1319 1320 1321 1322
	return 0;
}

/*
 * Set/clear bypassed status of a PG.
 * PGs are numbered upwards from 1 in the order they were declared.
 */
1323
static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
L
Linus Torvalds 已提交
1324 1325 1326
{
	struct priority_group *pg;
	unsigned pgnum;
1327
	char dummy;
L
Linus Torvalds 已提交
1328

1329
	if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1330
	    !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
L
Linus Torvalds 已提交
1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343
		DMWARN("invalid PG number supplied to bypass_pg");
		return -EINVAL;
	}

	list_for_each_entry(pg, &m->priority_groups, list) {
		if (!--pgnum)
			break;
	}

	bypass_pg(m, pg, bypassed);
	return 0;
}

D
Dave Wysochanski 已提交
1344 1345 1346
/*
 * Should we retry pg_init immediately?
 */
1347
static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
D
Dave Wysochanski 已提交
1348 1349
{
	unsigned long flags;
1350
	bool limit_reached = false;
D
Dave Wysochanski 已提交
1351 1352 1353

	spin_lock_irqsave(&m->lock, flags);

1354 1355
	if (atomic_read(&m->pg_init_count) <= m->pg_init_retries &&
	    !test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
1356
		set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
D
Dave Wysochanski 已提交
1357
	else
1358
		limit_reached = true;
D
Dave Wysochanski 已提交
1359 1360 1361 1362 1363 1364

	spin_unlock_irqrestore(&m->lock, flags);

	return limit_reached;
}

1365
static void pg_init_done(void *data, int errors)
1366
{
1367
	struct pgpath *pgpath = data;
1368 1369 1370
	struct priority_group *pg = pgpath->pg;
	struct multipath *m = pg->m;
	unsigned long flags;
1371
	bool delay_retry = false;
1372 1373 1374 1375 1376 1377 1378 1379 1380 1381

	/* device or driver problems */
	switch (errors) {
	case SCSI_DH_OK:
		break;
	case SCSI_DH_NOSYS:
		if (!m->hw_handler_name) {
			errors = 0;
			break;
		}
1382 1383
		DMERR("Could not failover the device: Handler scsi_dh_%s "
		      "Error %d.", m->hw_handler_name, errors);
1384 1385 1386 1387 1388 1389 1390 1391 1392 1393
		/*
		 * Fail path for now, so we do not ping pong
		 */
		fail_path(pgpath);
		break;
	case SCSI_DH_DEV_TEMP_BUSY:
		/*
		 * Probably doing something like FW upgrade on the
		 * controller so try the other pg.
		 */
1394
		bypass_pg(m, pg, true);
1395 1396
		break;
	case SCSI_DH_RETRY:
1397 1398
		/* Wait before retrying. */
		delay_retry = 1;
1399
		/* fall through */
1400 1401 1402 1403 1404 1405
	case SCSI_DH_IMM_RETRY:
	case SCSI_DH_RES_TEMP_UNAVAIL:
		if (pg_init_limit_reached(m, pgpath))
			fail_path(pgpath);
		errors = 0;
		break;
1406
	case SCSI_DH_DEV_OFFLINED:
1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417
	default:
		/*
		 * We probably do not want to fail the path for a device
		 * error, but this is what the old dm did. In future
		 * patches we can do more advanced handling.
		 */
		fail_path(pgpath);
	}

	spin_lock_irqsave(&m->lock, flags);
	if (errors) {
1418 1419 1420 1421 1422
		if (pgpath == m->current_pgpath) {
			DMERR("Could not failover device. Error %d.", errors);
			m->current_pgpath = NULL;
			m->current_pg = NULL;
		}
1423
	} else if (!test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1424
		pg->bypassed = false;
1425

1426
	if (atomic_dec_return(&m->pg_init_in_progress) > 0)
1427 1428 1429
		/* Activations of other paths are still on going */
		goto out;

1430 1431 1432 1433 1434 1435
	if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
		if (delay_retry)
			set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
		else
			clear_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);

1436 1437 1438
		if (__pg_init_all_paths(m))
			goto out;
	}
1439
	clear_bit(MPATHF_QUEUE_IO, &m->flags);
1440

1441
	process_queued_io_list(m);
1442

1443 1444 1445 1446 1447
	/*
	 * Wake up any thread waiting to suspend.
	 */
	wake_up(&m->pg_init_wait);

1448
out:
1449 1450 1451
	spin_unlock_irqrestore(&m->lock, flags);
}

1452
static void activate_or_offline_path(struct pgpath *pgpath)
1453
{
1454
	struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1455

1456 1457
	if (pgpath->is_active && !blk_queue_dying(q))
		scsi_dh_activate(q, pg_init_done, pgpath);
1458 1459
	else
		pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
1460 1461
}

1462 1463 1464 1465 1466 1467 1468 1469
static void activate_path_work(struct work_struct *work)
{
	struct pgpath *pgpath =
		container_of(work, struct pgpath, activate_path.work);

	activate_or_offline_path(pgpath);
}

1470
static int noretry_error(blk_status_t error)
1471 1472
{
	switch (error) {
1473 1474 1475 1476 1477
	case BLK_STS_NOTSUPP:
	case BLK_STS_NOSPC:
	case BLK_STS_TARGET:
	case BLK_STS_NEXUS:
	case BLK_STS_MEDIUM:
1478 1479 1480 1481 1482 1483 1484
		return 1;
	}

	/* Anything else could be a path failure, so should be retried */
	return 0;
}

1485
static int multipath_end_io(struct dm_target *ti, struct request *clone,
1486
			    blk_status_t error, union map_info *map_context)
L
Linus Torvalds 已提交
1487
{
1488 1489
	struct dm_mpath_io *mpio = get_mpio(map_context);
	struct pgpath *pgpath = mpio->pgpath;
1490
	int r = DM_ENDIO_DONE;
1491

1492 1493 1494 1495 1496
	/*
	 * We don't queue any clone request inside the multipath target
	 * during end I/O handling, since those clone requests don't have
	 * bio clones.  If we queue them inside the multipath target,
	 * we need to make bio clones, that requires memory allocation.
1497
	 * (See drivers/md/dm-rq.c:end_clone_bio() about why the clone requests
1498 1499 1500 1501 1502
	 *  don't have bio clones.)
	 * Instead of queueing the clone request here, we queue the original
	 * request into dm core, which will remake a clone request and
	 * clone bios for it and resubmit it later.
	 */
1503 1504
	if (error && !noretry_error(error)) {
		struct multipath *m = ti->private;
L
Linus Torvalds 已提交
1505

1506
		r = DM_ENDIO_REQUEUE;
L
Linus Torvalds 已提交
1507

1508 1509
		if (pgpath)
			fail_path(pgpath);
L
Linus Torvalds 已提交
1510

1511
		if (atomic_read(&m->nr_valid_paths) == 0 &&
1512
		    !must_push_back_rq(m)) {
1513
			if (error == BLK_STS_IOERR)
1514
				dm_report_EIO(m);
1515 1516 1517
			/* complete with the original error */
			r = DM_ENDIO_DONE;
		}
1518
	}
1519

L
Linus Torvalds 已提交
1520
	if (pgpath) {
1521 1522
		struct path_selector *ps = &pgpath->pg->ps;

L
Linus Torvalds 已提交
1523
		if (ps->type->end_io)
1524
			ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
L
Linus Torvalds 已提交
1525 1526
	}

1527
	return r;
L
Linus Torvalds 已提交
1528 1529
}

1530 1531
static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
		blk_status_t *error)
1532
{
1533 1534 1535
	struct multipath *m = ti->private;
	struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
	struct pgpath *pgpath = mpio->pgpath;
1536
	unsigned long flags;
1537
	int r = DM_ENDIO_DONE;
1538

1539
	if (!*error || noretry_error(*error))
1540
		goto done;
1541

1542 1543
	if (pgpath)
		fail_path(pgpath);
1544

1545
	if (atomic_read(&m->nr_valid_paths) == 0 &&
1546
	    !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1547 1548 1549 1550 1551 1552
		if (must_push_back_bio(m)) {
			r = DM_ENDIO_REQUEUE;
		} else {
			dm_report_EIO(m);
			*error = BLK_STS_IOERR;
		}
1553
		goto done;
1554
	}
1555 1556 1557 1558 1559 1560 1561

	spin_lock_irqsave(&m->lock, flags);
	bio_list_add(&m->queued_bios, clone);
	spin_unlock_irqrestore(&m->lock, flags);
	if (!test_bit(MPATHF_QUEUE_IO, &m->flags))
		queue_work(kmultipathd, &m->process_queued_bios);

1562
	r = DM_ENDIO_INCOMPLETE;
1563
done:
1564
	if (pgpath) {
1565 1566
		struct path_selector *ps = &pgpath->pg->ps;

1567 1568 1569 1570
		if (ps->type->end_io)
			ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
	}

1571
	return r;
1572 1573
}

L
Linus Torvalds 已提交
1574 1575
/*
 * Suspend can't complete until all the I/O is processed so if
1576 1577 1578
 * the last path fails we must error any remaining I/O.
 * Note that if the freeze_bdev fails while suspending, the
 * queue_if_no_path state is lost - userspace should reset it.
L
Linus Torvalds 已提交
1579 1580 1581
 */
static void multipath_presuspend(struct dm_target *ti)
{
1582
	struct multipath *m = ti->private;
L
Linus Torvalds 已提交
1583

1584
	queue_if_no_path(m, false, true);
L
Linus Torvalds 已提交
1585 1586
}

1587 1588
static void multipath_postsuspend(struct dm_target *ti)
{
1589 1590 1591
	struct multipath *m = ti->private;

	mutex_lock(&m->work_mutex);
1592
	flush_multipath_work(m);
1593
	mutex_unlock(&m->work_mutex);
1594 1595
}

1596 1597 1598
/*
 * Restore the queue_if_no_path setting.
 */
L
Linus Torvalds 已提交
1599 1600
static void multipath_resume(struct dm_target *ti)
{
1601
	struct multipath *m = ti->private;
1602
	unsigned long flags;
L
Linus Torvalds 已提交
1603

1604
	spin_lock_irqsave(&m->lock, flags);
L
Lukas Wunner 已提交
1605 1606
	assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags,
		   test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags));
1607
	spin_unlock_irqrestore(&m->lock, flags);
L
Linus Torvalds 已提交
1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625
}

/*
 * Info output has the following format:
 * num_multipath_feature_args [multipath_feature_args]*
 * num_handler_status_args [handler_status_args]*
 * num_groups init_group_number
 *            [A|D|E num_ps_status_args [ps_status_args]*
 *             num_paths num_selector_args
 *             [path_dev A|F fail_count [selector_args]* ]+ ]+
 *
 * Table output has the following format (identical to the constructor string):
 * num_feature_args [features_args]*
 * num_handler_args hw_handler [hw_handler_args]*
 * num_groups init_group_number
 *     [priority selector-name num_ps_args [ps_args]*
 *      num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
 */
1626 1627
static void multipath_status(struct dm_target *ti, status_type_t type,
			     unsigned status_flags, char *result, unsigned maxlen)
L
Linus Torvalds 已提交
1628 1629 1630
{
	int sz = 0;
	unsigned long flags;
1631
	struct multipath *m = ti->private;
L
Linus Torvalds 已提交
1632 1633 1634 1635 1636 1637 1638 1639 1640
	struct priority_group *pg;
	struct pgpath *p;
	unsigned pg_num;
	char state;

	spin_lock_irqsave(&m->lock, flags);

	/* Features */
	if (type == STATUSTYPE_INFO)
1641 1642
		DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO, &m->flags),
		       atomic_read(&m->pg_init_count));
D
Dave Wysochanski 已提交
1643
	else {
1644
		DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
1645
			      (m->pg_init_retries > 0) * 2 +
1646
			      (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1647 1648 1649
			      test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) +
			      (m->queue_mode != DM_TYPE_REQUEST_BASED) * 2);

1650
		if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
D
Dave Wysochanski 已提交
1651 1652 1653
			DMEMIT("queue_if_no_path ");
		if (m->pg_init_retries)
			DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1654 1655
		if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
			DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1656
		if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
1657
			DMEMIT("retain_attached_hw_handler ");
1658 1659 1660 1661 1662 1663 1664 1665
		if (m->queue_mode != DM_TYPE_REQUEST_BASED) {
			switch(m->queue_mode) {
			case DM_TYPE_BIO_BASED:
				DMEMIT("queue_mode bio ");
				break;
			case DM_TYPE_MQ_REQUEST_BASED:
				DMEMIT("queue_mode mq ");
				break;
1666 1667 1668
			default:
				WARN_ON_ONCE(true);
				break;
1669 1670
			}
		}
D
Dave Wysochanski 已提交
1671
	}
L
Linus Torvalds 已提交
1672

1673
	if (!m->hw_handler_name || type == STATUSTYPE_INFO)
L
Linus Torvalds 已提交
1674 1675
		DMEMIT("0 ");
	else
1676
		DMEMIT("1 %s ", m->hw_handler_name);
L
Linus Torvalds 已提交
1677 1678 1679 1680 1681 1682 1683 1684

	DMEMIT("%u ", m->nr_priority_groups);

	if (m->next_pg)
		pg_num = m->next_pg->pg_num;
	else if (m->current_pg)
		pg_num = m->current_pg->pg_num;
	else
1685
		pg_num = (m->nr_priority_groups ? 1 : 0);
L
Linus Torvalds 已提交
1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712

	DMEMIT("%u ", pg_num);

	switch (type) {
	case STATUSTYPE_INFO:
		list_for_each_entry(pg, &m->priority_groups, list) {
			if (pg->bypassed)
				state = 'D';	/* Disabled */
			else if (pg == m->current_pg)
				state = 'A';	/* Currently Active */
			else
				state = 'E';	/* Enabled */

			DMEMIT("%c ", state);

			if (pg->ps.type->status)
				sz += pg->ps.type->status(&pg->ps, NULL, type,
							  result + sz,
							  maxlen - sz);
			else
				DMEMIT("0 ");

			DMEMIT("%u %u ", pg->nr_pgpaths,
			       pg->ps.type->info_args);

			list_for_each_entry(p, &pg->pgpaths, list) {
				DMEMIT("%s %s %u ", p->path.dev->name,
1713
				       p->is_active ? "A" : "F",
L
Linus Torvalds 已提交
1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752
				       p->fail_count);
				if (pg->ps.type->status)
					sz += pg->ps.type->status(&pg->ps,
					      &p->path, type, result + sz,
					      maxlen - sz);
			}
		}
		break;

	case STATUSTYPE_TABLE:
		list_for_each_entry(pg, &m->priority_groups, list) {
			DMEMIT("%s ", pg->ps.type->name);

			if (pg->ps.type->status)
				sz += pg->ps.type->status(&pg->ps, NULL, type,
							  result + sz,
							  maxlen - sz);
			else
				DMEMIT("0 ");

			DMEMIT("%u %u ", pg->nr_pgpaths,
			       pg->ps.type->table_args);

			list_for_each_entry(p, &pg->pgpaths, list) {
				DMEMIT("%s ", p->path.dev->name);
				if (pg->ps.type->status)
					sz += pg->ps.type->status(&pg->ps,
					      &p->path, type, result + sz,
					      maxlen - sz);
			}
		}
		break;
	}

	spin_unlock_irqrestore(&m->lock, flags);
}

static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
{
1753
	int r = -EINVAL;
L
Linus Torvalds 已提交
1754
	struct dm_dev *dev;
1755
	struct multipath *m = ti->private;
L
Linus Torvalds 已提交
1756 1757
	action_fn action;

1758 1759
	mutex_lock(&m->work_mutex);

1760 1761 1762 1763 1764
	if (dm_suspended(ti)) {
		r = -EBUSY;
		goto out;
	}

L
Linus Torvalds 已提交
1765
	if (argc == 1) {
1766
		if (!strcasecmp(argv[0], "queue_if_no_path")) {
1767
			r = queue_if_no_path(m, true, false);
1768
			goto out;
1769
		} else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1770
			r = queue_if_no_path(m, false, false);
1771 1772
			goto out;
		}
L
Linus Torvalds 已提交
1773 1774
	}

1775
	if (argc != 2) {
1776
		DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
1777 1778
		goto out;
	}
L
Linus Torvalds 已提交
1779

1780
	if (!strcasecmp(argv[0], "disable_group")) {
1781
		r = bypass_pg_num(m, argv[1], true);
1782
		goto out;
1783
	} else if (!strcasecmp(argv[0], "enable_group")) {
1784
		r = bypass_pg_num(m, argv[1], false);
1785
		goto out;
1786
	} else if (!strcasecmp(argv[0], "switch_group")) {
1787 1788
		r = switch_pg_num(m, argv[1]);
		goto out;
1789
	} else if (!strcasecmp(argv[0], "reinstate_path"))
L
Linus Torvalds 已提交
1790
		action = reinstate_path;
1791
	else if (!strcasecmp(argv[0], "fail_path"))
L
Linus Torvalds 已提交
1792
		action = fail_path;
1793
	else {
1794
		DMWARN("Unrecognised multipath message received: %s", argv[0]);
1795 1796
		goto out;
	}
L
Linus Torvalds 已提交
1797

1798
	r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
L
Linus Torvalds 已提交
1799
	if (r) {
1800
		DMWARN("message: error getting device %s",
L
Linus Torvalds 已提交
1801
		       argv[1]);
1802
		goto out;
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Linus Torvalds 已提交
1803 1804 1805 1806 1807 1808
	}

	r = action_dev(m, dev, action);

	dm_put_device(ti, dev);

1809 1810
out:
	mutex_unlock(&m->work_mutex);
L
Linus Torvalds 已提交
1811 1812 1813
	return r;
}

C
Christoph Hellwig 已提交
1814 1815
static int multipath_prepare_ioctl(struct dm_target *ti,
		struct block_device **bdev, fmode_t *mode)
M
Milan Broz 已提交
1816
{
1817
	struct multipath *m = ti->private;
1818
	struct pgpath *current_pgpath;
1819 1820
	int r;

1821
	current_pgpath = READ_ONCE(m->current_pgpath);
1822 1823
	if (!current_pgpath)
		current_pgpath = choose_pgpath(m, 0);
M
Milan Broz 已提交
1824

1825
	if (current_pgpath) {
1826
		if (!test_bit(MPATHF_QUEUE_IO, &m->flags)) {
1827 1828
			*bdev = current_pgpath->path.dev->bdev;
			*mode = current_pgpath->path.dev->mode;
1829 1830 1831 1832 1833 1834 1835
			r = 0;
		} else {
			/* pg_init has not started or completed */
			r = -ENOTCONN;
		}
	} else {
		/* No path is available */
1836
		if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1837 1838 1839
			r = -ENOTCONN;
		else
			r = -EIO;
1840
	}
M
Milan Broz 已提交
1841

1842
	if (r == -ENOTCONN) {
1843
		if (!READ_ONCE(m->current_pg)) {
1844
			/* Path status changed, redo selection */
1845
			(void) choose_pgpath(m, 0);
1846
		}
1847
		if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1848
			pg_init_all_paths(m);
1849
		dm_table_run_md_queue_async(m->ti->table);
1850
		process_queued_io_list(m);
1851
	}
1852

C
Christoph Hellwig 已提交
1853 1854 1855 1856 1857 1858
	/*
	 * Only pass ioctls through if the device sizes match exactly.
	 */
	if (!r && ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
		return 1;
	return r;
M
Milan Broz 已提交
1859 1860
}

1861 1862 1863 1864 1865 1866 1867 1868 1869 1870
static int multipath_iterate_devices(struct dm_target *ti,
				     iterate_devices_callout_fn fn, void *data)
{
	struct multipath *m = ti->private;
	struct priority_group *pg;
	struct pgpath *p;
	int ret = 0;

	list_for_each_entry(pg, &m->priority_groups, list) {
		list_for_each_entry(p, &pg->pgpaths, list) {
1871
			ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1872 1873 1874 1875 1876 1877 1878 1879 1880
			if (ret)
				goto out;
		}
	}

out:
	return ret;
}

1881
static int pgpath_busy(struct pgpath *pgpath)
1882 1883 1884
{
	struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);

1885
	return blk_lld_busy(q);
1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897
}

/*
 * We return "busy", only when we can map I/Os but underlying devices
 * are busy (so even if we map I/Os now, the I/Os will wait on
 * the underlying queue).
 * In other words, if we want to kill I/Os or queue them inside us
 * due to map unavailability, we don't return "busy".  Otherwise,
 * dm core won't give us the I/Os and we can't do what we want.
 */
static int multipath_busy(struct dm_target *ti)
{
1898
	bool busy = false, has_active = false;
1899
	struct multipath *m = ti->private;
1900
	struct priority_group *pg, *next_pg;
1901 1902
	struct pgpath *pgpath;

1903 1904
	/* pg_init in progress */
	if (atomic_read(&m->pg_init_in_progress))
1905 1906
		return true;

1907 1908 1909 1910
	/* no paths available, for blk-mq: rely on IO mapping to delay requeue */
	if (!atomic_read(&m->nr_valid_paths) && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
		return (m->queue_mode != DM_TYPE_MQ_REQUEST_BASED);

1911
	/* Guess which priority_group will be used at next mapping time */
1912 1913 1914
	pg = READ_ONCE(m->current_pg);
	next_pg = READ_ONCE(m->next_pg);
	if (unlikely(!READ_ONCE(m->current_pgpath) && next_pg))
1915 1916 1917
		pg = next_pg;

	if (!pg) {
1918 1919
		/*
		 * We don't know which pg will be used at next mapping time.
1920
		 * We don't call choose_pgpath() here to avoid to trigger
1921 1922 1923 1924
		 * pg_init just by busy checking.
		 * So we don't know whether underlying devices we will be using
		 * at next mapping time are busy or not. Just try mapping.
		 */
1925 1926
		return busy;
	}
1927 1928 1929 1930 1931

	/*
	 * If there is one non-busy active path at least, the path selector
	 * will be able to select it. So we consider such a pg as not busy.
	 */
1932
	busy = true;
1933
	list_for_each_entry(pgpath, &pg->pgpaths, list) {
1934
		if (pgpath->is_active) {
1935
			has_active = true;
1936
			if (!pgpath_busy(pgpath)) {
1937
				busy = false;
1938 1939 1940
				break;
			}
		}
1941
	}
1942

1943
	if (!has_active) {
1944 1945 1946 1947 1948
		/*
		 * No active path in this pg, so this pg won't be used and
		 * the current_pg will be changed at next mapping time.
		 * We need to try mapping to determine it.
		 */
1949
		busy = false;
1950
	}
1951 1952 1953 1954

	return busy;
}

L
Linus Torvalds 已提交
1955 1956 1957 1958 1959
/*-----------------------------------------------------------------
 * Module setup
 *---------------------------------------------------------------*/
static struct target_type multipath_target = {
	.name = "multipath",
1960
	.version = {1, 12, 0},
M
Mike Snitzer 已提交
1961
	.features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
L
Linus Torvalds 已提交
1962 1963 1964
	.module = THIS_MODULE,
	.ctr = multipath_ctr,
	.dtr = multipath_dtr,
1965 1966
	.clone_and_map_rq = multipath_clone_and_map,
	.release_clone_rq = multipath_release_clone,
1967
	.rq_end_io = multipath_end_io,
1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979
	.map = multipath_map_bio,
	.end_io = multipath_end_io_bio,
	.presuspend = multipath_presuspend,
	.postsuspend = multipath_postsuspend,
	.resume = multipath_resume,
	.status = multipath_status,
	.message = multipath_message,
	.prepare_ioctl = multipath_prepare_ioctl,
	.iterate_devices = multipath_iterate_devices,
	.busy = multipath_busy,
};

L
Linus Torvalds 已提交
1980 1981 1982 1983
static int __init dm_multipath_init(void)
{
	int r;

1984
	kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
1985
	if (!kmultipathd) {
1986
		DMERR("failed to create workqueue kmpathd");
1987 1988
		r = -ENOMEM;
		goto bad_alloc_kmultipathd;
1989 1990
	}

1991 1992 1993 1994 1995 1996
	/*
	 * A separate workqueue is used to handle the device handlers
	 * to avoid overloading existing workqueue. Overloading the
	 * old workqueue would also create a bottleneck in the
	 * path of the storage hardware device activation.
	 */
1997 1998
	kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
						  WQ_MEM_RECLAIM);
1999 2000
	if (!kmpath_handlerd) {
		DMERR("failed to create workqueue kmpath_handlerd");
2001 2002
		r = -ENOMEM;
		goto bad_alloc_kmpath_handlerd;
2003 2004
	}

2005 2006 2007 2008 2009 2010 2011
	r = dm_register_target(&multipath_target);
	if (r < 0) {
		DMERR("request-based register failed %d", r);
		r = -EINVAL;
		goto bad_register_target;
	}

2012 2013
	return 0;

2014 2015
bad_register_target:
	destroy_workqueue(kmpath_handlerd);
2016 2017 2018
bad_alloc_kmpath_handlerd:
	destroy_workqueue(kmultipathd);
bad_alloc_kmultipathd:
L
Linus Torvalds 已提交
2019 2020 2021 2022 2023
	return r;
}

static void __exit dm_multipath_exit(void)
{
2024
	destroy_workqueue(kmpath_handlerd);
2025 2026
	destroy_workqueue(kmultipathd);

2027
	dm_unregister_target(&multipath_target);
L
Linus Torvalds 已提交
2028 2029 2030 2031 2032 2033 2034 2035
}

module_init(dm_multipath_init);
module_exit(dm_multipath_exit);

MODULE_DESCRIPTION(DM_NAME " multipath target");
MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");