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dm-mpath.c
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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.
*/
#include <linux/device-mapper.h>
#include "dm-rq.h"
#include "dm-bio-record.h"
#include "dm-path-selector.h"
#include "dm-uevent.h"
#include <linux/blkdev.h>
#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/timer.h>
#include <linux/workqueue.h>
#include <linux/delay.h>
#include <scsi/scsi_dh.h>
#include <linux/atomic.h>
#include <linux/blk-mq.h>
#define DM_MSG_PREFIX "multipath"
#define DM_PG_INIT_DELAY_MSECS 2000
#define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1)
#define QUEUE_IF_NO_PATH_TIMEOUT_DEFAULT 0
static unsigned long queue_if_no_path_timeout_secs = QUEUE_IF_NO_PATH_TIMEOUT_DEFAULT;
/* Path properties */
struct pgpath {
struct list_head list;
struct priority_group *pg; /* Owning PG */
unsigned fail_count; /* Cumulative failure count */
struct dm_path path;
struct delayed_work activate_path;
bool is_active:1; /* Path status */
};
#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;
bool bypassed:1; /* Temporarily bypass this PG? */
};
/* Multipath context */
struct multipath {
unsigned long flags; /* Multipath state flags */
spinlock_t lock;
enum dm_queue_mode queue_mode;
struct pgpath *current_pgpath;
struct priority_group *current_pg;
struct priority_group *next_pg; /* Switch to this PG if set */
atomic_t nr_valid_paths; /* Total number of usable paths */
unsigned nr_priority_groups;
struct list_head priority_groups;
const char *hw_handler_name;
char *hw_handler_params;
wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
unsigned pg_init_retries; /* Number of times to retry pg_init */
unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */
atomic_t pg_init_in_progress; /* Only one pg_init allowed at once */
atomic_t pg_init_count; /* Number of times pg_init called */
struct mutex work_mutex;
struct work_struct trigger_event;
struct dm_target *ti;
struct work_struct process_queued_bios;
struct bio_list queued_bios;
struct timer_list nopath_timer; /* Timeout for queue_if_no_path */
};
/*
* Context information attached to each io we process.
*/
struct dm_mpath_io {
struct pgpath *pgpath;
size_t nr_bytes;
};
typedef int (*action_fn) (struct pgpath *pgpath);
static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
static void trigger_event(struct work_struct *work);
static void activate_or_offline_path(struct pgpath *pgpath);
static void activate_path_work(struct work_struct *work);
static void process_queued_bios(struct work_struct *work);
static void queue_if_no_path_timeout_work(struct timer_list *t);
/*-----------------------------------------------
* 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? */
static bool mpath_double_check_test_bit(int MPATHF_bit, struct multipath *m)
{
bool r = test_bit(MPATHF_bit, &m->flags);
if (r) {
unsigned long flags;
spin_lock_irqsave(&m->lock, flags);
r = test_bit(MPATHF_bit, &m->flags);
spin_unlock_irqrestore(&m->lock, flags);
}
return r;
}
/*-----------------------------------------------
* Allocation routines
*-----------------------------------------------*/
static struct pgpath *alloc_pgpath(void)
{
struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
if (!pgpath)
return NULL;
pgpath->is_active = true;
return pgpath;
}
static void free_pgpath(struct pgpath *pgpath)
{
kfree(pgpath);
}
static struct priority_group *alloc_priority_group(void)
{
struct priority_group *pg;
pg = kzalloc(sizeof(*pg), GFP_KERNEL);
if (pg)
INIT_LIST_HEAD(&pg->pgpaths);
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);
}
static struct multipath *alloc_multipath(struct dm_target *ti)
{
struct multipath *m;
m = kzalloc(sizeof(*m), GFP_KERNEL);
if (m) {
INIT_LIST_HEAD(&m->priority_groups);
spin_lock_init(&m->lock);
atomic_set(&m->nr_valid_paths, 0);
INIT_WORK(&m->trigger_event, trigger_event);
mutex_init(&m->work_mutex);
m->queue_mode = DM_TYPE_NONE;
m->ti = ti;
ti->private = m;
timer_setup(&m->nopath_timer, queue_if_no_path_timeout_work, 0);
}
return m;
}
static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m)
{
if (m->queue_mode == DM_TYPE_NONE) {
m->queue_mode = DM_TYPE_REQUEST_BASED;
} else if (m->queue_mode == DM_TYPE_BIO_BASED) {
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);
/*
* Init fields that are only used when a scsi_dh is attached
* - must do this unconditionally (really doesn't hurt non-SCSI uses)
*/
set_bit(MPATHF_QUEUE_IO, &m->flags);
atomic_set(&m->pg_init_in_progress, 0);
atomic_set(&m->pg_init_count, 0);
m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
init_waitqueue_head(&m->pg_init_wait);
return 0;
}
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);
}
kfree(m->hw_handler_name);
kfree(m->hw_handler_params);
mutex_destroy(&m->work_mutex);
kfree(m);
}
static struct dm_mpath_io *get_mpio(union map_info *info)
{
return info->ptr;
}
static size_t multipath_per_bio_data_size(void)
{
return sizeof(struct dm_mpath_io) + sizeof(struct dm_bio_details);
}
static struct dm_mpath_io *get_mpio_from_bio(struct bio *bio)
{
return dm_per_bio_data(bio, multipath_per_bio_data_size());
}
static struct dm_bio_details *get_bio_details_from_mpio(struct dm_mpath_io *mpio)
{
/* dm_bio_details is immediately after the dm_mpath_io in bio's per-bio-data */
void *bio_details = mpio + 1;
return bio_details;
}
static void multipath_init_per_bio_data(struct bio *bio, struct dm_mpath_io **mpio_p)
{
struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
struct dm_bio_details *bio_details = get_bio_details_from_mpio(mpio);
mpio->nr_bytes = bio->bi_iter.bi_size;
mpio->pgpath = NULL;
*mpio_p = mpio;
dm_bio_record(bio_details, bio);
}
/*-----------------------------------------------
* Path selection
*-----------------------------------------------*/
static int __pg_init_all_paths(struct multipath *m)
{
struct pgpath *pgpath;
unsigned long pg_init_delay = 0;
lockdep_assert_held(&m->lock);
if (atomic_read(&m->pg_init_in_progress) || test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
return 0;
atomic_inc(&m->pg_init_count);
clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
/* Check here to reset pg_init_required */
if (!m->current_pg)
return 0;
if (test_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags))
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);
list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
/* Skip failed paths */
if (!pgpath->is_active)
continue;
if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path,
pg_init_delay))
atomic_inc(&m->pg_init_in_progress);
}
return atomic_read(&m->pg_init_in_progress);
}
static int pg_init_all_paths(struct multipath *m)
{
int ret;
unsigned long flags;
spin_lock_irqsave(&m->lock, flags);
ret = __pg_init_all_paths(m);
spin_unlock_irqrestore(&m->lock, flags);
return ret;
}
static void __switch_pg(struct multipath *m, struct priority_group *pg)
{
lockdep_assert_held(&m->lock);
m->current_pg = pg;
/* Must we initialise the PG first, and queue I/O till it's ready? */
if (m->hw_handler_name) {
set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
set_bit(MPATHF_QUEUE_IO, &m->flags);
} else {
clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
clear_bit(MPATHF_QUEUE_IO, &m->flags);
}
atomic_set(&m->pg_init_count, 0);
}
static struct pgpath *choose_path_in_pg(struct multipath *m,
struct priority_group *pg,
size_t nr_bytes)
{
unsigned long flags;
struct dm_path *path;
struct pgpath *pgpath;
path = pg->ps.type->select_path(&pg->ps, nr_bytes);
if (!path)
return ERR_PTR(-ENXIO);
pgpath = path_to_pgpath(path);
if (unlikely(READ_ONCE(m->current_pg) != pg)) {
/* 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);
}
return pgpath;
}
static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes)
{
unsigned long flags;
struct priority_group *pg;
struct pgpath *pgpath;
unsigned bypassed = 1;
if (!atomic_read(&m->nr_valid_paths)) {
spin_lock_irqsave(&m->lock, flags);
clear_bit(MPATHF_QUEUE_IO, &m->flags);
spin_unlock_irqrestore(&m->lock, flags);
goto failed;
}
/* Were we instructed to switch PG? */
if (READ_ONCE(m->next_pg)) {
spin_lock_irqsave(&m->lock, flags);
pg = m->next_pg;
if (!pg) {
spin_unlock_irqrestore(&m->lock, flags);
goto check_current_pg;
}
m->next_pg = NULL;
spin_unlock_irqrestore(&m->lock, flags);
pgpath = choose_path_in_pg(m, pg, nr_bytes);
if (!IS_ERR_OR_NULL(pgpath))
return pgpath;
}
/* Don't change PG until it has no remaining paths */
check_current_pg:
pg = READ_ONCE(m->current_pg);
if (pg) {
pgpath = choose_path_in_pg(m, pg, nr_bytes);
if (!IS_ERR_OR_NULL(pgpath))
return pgpath;
}
/*
* Loop through priority groups until we find a valid path.
* First time we skip PGs marked 'bypassed'.
* Second time we only try the ones we skipped, but set
* pg_init_delay_retry so we do not hammer controllers.
*/
do {
list_for_each_entry(pg, &m->priority_groups, list) {
if (pg->bypassed == !!bypassed)
continue;
pgpath = choose_path_in_pg(m, pg, nr_bytes);
if (!IS_ERR_OR_NULL(pgpath)) {
if (!bypassed) {
spin_lock_irqsave(&m->lock, flags);
set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
spin_unlock_irqrestore(&m->lock, flags);
}
return pgpath;
}
}
} while (bypassed--);
failed:
spin_lock_irqsave(&m->lock, flags);
m->current_pgpath = NULL;
m->current_pg = NULL;
spin_unlock_irqrestore(&m->lock, flags);
return NULL;
}
/*
* dm_report_EIO() is a macro instead of a function to make pr_debug_ratelimited()
* report the function name and line number of the function from which
* it has been invoked.
*/
#define dm_report_EIO(m) \
do { \
DMDEBUG_LIMIT("%s: returning EIO; QIFNP = %d; SQIFNP = %d; DNFS = %d", \
dm_table_device_name((m)->ti->table), \
test_bit(MPATHF_QUEUE_IF_NO_PATH, &(m)->flags), \
test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &(m)->flags), \
dm_noflush_suspending((m)->ti)); \
} while (0)
/*
* Check whether bios must be queued in the device-mapper core rather
* than here in the target.
*/
static bool __must_push_back(struct multipath *m)
{
return dm_noflush_suspending(m->ti);
}
static bool must_push_back_rq(struct multipath *m)
{
unsigned long flags;
bool ret;
spin_lock_irqsave(&m->lock, flags);
ret = (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) || __must_push_back(m));
spin_unlock_irqrestore(&m->lock, flags);
return ret;
}
/*
* Map cloned requests (request-based multipath)
*/
static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
union map_info *map_context,
struct request **__clone)
{
struct multipath *m = ti->private;
size_t nr_bytes = blk_rq_bytes(rq);
struct pgpath *pgpath;
struct block_device *bdev;
struct dm_mpath_io *mpio = get_mpio(map_context);
struct request_queue *q;
struct request *clone;
/* Do we need to select a new pgpath? */
pgpath = READ_ONCE(m->current_pgpath);
if (!pgpath || !mpath_double_check_test_bit(MPATHF_QUEUE_IO, m))
pgpath = choose_pgpath(m, nr_bytes);
if (!pgpath) {
if (must_push_back_rq(m))
return DM_MAPIO_DELAY_REQUEUE;
dm_report_EIO(m); /* Failed */
return DM_MAPIO_KILL;
} else if (mpath_double_check_test_bit(MPATHF_QUEUE_IO, m) ||
mpath_double_check_test_bit(MPATHF_PG_INIT_REQUIRED, m)) {
pg_init_all_paths(m);
return DM_MAPIO_DELAY_REQUEUE;
}
mpio->pgpath = pgpath;
mpio->nr_bytes = nr_bytes;
bdev = pgpath->path.dev->bdev;
q = bdev_get_queue(bdev);
clone = blk_mq_alloc_request(q, rq->cmd_flags | REQ_NOMERGE,
BLK_MQ_REQ_NOWAIT);
if (IS_ERR(clone)) {
/* EBUSY, ENODEV or EWOULDBLOCK: requeue */
if (blk_queue_dying(q)) {
atomic_inc(&m->pg_init_in_progress);
activate_or_offline_path(pgpath);
return DM_MAPIO_DELAY_REQUEUE;
}
/*
* blk-mq's SCHED_RESTART can cover this requeue, so we
* needn't deal with it by DELAY_REQUEUE. More importantly,
* we have to return DM_MAPIO_REQUEUE so that blk-mq can
* get the queue busy feedback (via BLK_STS_RESOURCE),
* otherwise I/O merging can suffer.
*/
return DM_MAPIO_REQUEUE;
}
clone->bio = clone->biotail = NULL;
clone->rq_disk = bdev->bd_disk;
clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
*__clone = clone;
if (pgpath->pg->ps.type->start_io)
pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
&pgpath->path,
nr_bytes);
return DM_MAPIO_REMAPPED;
}
static void multipath_release_clone(struct request *clone,
union map_info *map_context)
{
if (unlikely(map_context)) {
/*
* non-NULL map_context means caller is still map
* method; must undo multipath_clone_and_map()
*/
struct dm_mpath_io *mpio = get_mpio(map_context);
struct pgpath *pgpath = mpio->pgpath;
if (pgpath && pgpath->pg->ps.type->end_io)
pgpath->pg->ps.type->end_io(&pgpath->pg->ps,
&pgpath->path,
mpio->nr_bytes,
clone->io_start_time_ns);
}
blk_mq_free_request(clone);
}
/*
* Map cloned bios (bio-based multipath)
*/
static void __multipath_queue_bio(struct multipath *m, struct bio *bio)
{
/* Queue for the daemon to resubmit */
bio_list_add(&m->queued_bios, bio);
if (!test_bit(MPATHF_QUEUE_IO, &m->flags))
queue_work(kmultipathd, &m->process_queued_bios);
}
static void multipath_queue_bio(struct multipath *m, struct bio *bio)
{
unsigned long flags;
spin_lock_irqsave(&m->lock, flags);
__multipath_queue_bio(m, bio);
spin_unlock_irqrestore(&m->lock, flags);
}
static struct pgpath *__map_bio(struct multipath *m, struct bio *bio)
{
struct pgpath *pgpath;
unsigned long flags;
/* Do we need to select a new pgpath? */
pgpath = READ_ONCE(m->current_pgpath);
if (!pgpath || !mpath_double_check_test_bit(MPATHF_QUEUE_IO, m))
pgpath = choose_pgpath(m, bio->bi_iter.bi_size);
if (!pgpath) {
spin_lock_irqsave(&m->lock, flags);
if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
__multipath_queue_bio(m, bio);
pgpath = ERR_PTR(-EAGAIN);
}
spin_unlock_irqrestore(&m->lock, flags);
} else if (mpath_double_check_test_bit(MPATHF_QUEUE_IO, m) ||
mpath_double_check_test_bit(MPATHF_PG_INIT_REQUIRED, m)) {
multipath_queue_bio(m, bio);
pg_init_all_paths(m);
return ERR_PTR(-EAGAIN);
}
return pgpath;
}
static int __multipath_map_bio(struct multipath *m, struct bio *bio,
struct dm_mpath_io *mpio)
{
struct pgpath *pgpath = __map_bio(m, bio);
if (IS_ERR(pgpath))
return DM_MAPIO_SUBMITTED;
if (!pgpath) {
if (__must_push_back(m))
return DM_MAPIO_REQUEUE;
dm_report_EIO(m);
return DM_MAPIO_KILL;
}
mpio->pgpath = pgpath;
bio->bi_status = 0;
bio_set_dev(bio, pgpath->path.dev->bdev);
bio->bi_opf |= REQ_FAILFAST_TRANSPORT;
if (pgpath->pg->ps.type->start_io)
pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
&pgpath->path,
mpio->nr_bytes);
return DM_MAPIO_REMAPPED;
}
static int multipath_map_bio(struct dm_target *ti, struct bio *bio)
{
struct multipath *m = ti->private;
struct dm_mpath_io *mpio = NULL;
multipath_init_per_bio_data(bio, &mpio);
return __multipath_map_bio(m, bio, mpio);
}
static void process_queued_io_list(struct multipath *m)
{
if (m->queue_mode == DM_TYPE_REQUEST_BASED)
dm_mq_kick_requeue_list(dm_table_get_md(m->ti->table));
else if (m->queue_mode == DM_TYPE_BIO_BASED)
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))) {
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);
switch (r) {
case DM_MAPIO_KILL:
bio->bi_status = BLK_STS_IOERR;
bio_endio(bio);
break;
case DM_MAPIO_REQUEUE:
bio->bi_status = BLK_STS_DM_REQUEUE;
bio_endio(bio);
break;
case DM_MAPIO_REMAPPED:
submit_bio_noacct(bio);
break;
case DM_MAPIO_SUBMITTED:
break;
default:
WARN_ONCE(true, "__multipath_map_bio() returned %d\n", r);
}
}
blk_finish_plug(&plug);
}
/*
* If we run out of usable paths, should we queue I/O or error it?
*/
static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
bool save_old_value, const char *caller)
{
unsigned long flags;
bool queue_if_no_path_bit, saved_queue_if_no_path_bit;
const char *dm_dev_name = dm_table_device_name(m->ti->table);
DMDEBUG("%s: %s caller=%s queue_if_no_path=%d save_old_value=%d",
dm_dev_name, __func__, caller, queue_if_no_path, save_old_value);
spin_lock_irqsave(&m->lock, flags);
queue_if_no_path_bit = test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
saved_queue_if_no_path_bit = test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
if (save_old_value) {
if (unlikely(!queue_if_no_path_bit && saved_queue_if_no_path_bit)) {
DMERR("%s: QIFNP disabled but saved as enabled, saving again loses state, not saving!",
dm_dev_name);
} else
assign_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags, queue_if_no_path_bit);
} else if (!queue_if_no_path && saved_queue_if_no_path_bit) {
/* due to "fail_if_no_path" message, need to honor it. */
clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
}
assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags, queue_if_no_path);
DMDEBUG("%s: after %s changes; QIFNP = %d; SQIFNP = %d; DNFS = %d",
dm_dev_name, __func__,
test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags),
test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags),
dm_noflush_suspending(m->ti));
spin_unlock_irqrestore(&m->lock, flags);
if (!queue_if_no_path) {
dm_table_run_md_queue_async(m->ti->table);
process_queued_io_list(m);
}
return 0;
}
/*
* If the queue_if_no_path timeout fires, turn off queue_if_no_path and
* process any queued I/O.
*/
static void queue_if_no_path_timeout_work(struct timer_list *t)
{
struct multipath *m = from_timer(m, t, nopath_timer);
DMWARN("queue_if_no_path timeout on %s, failing queued IO",
dm_table_device_name(m->ti->table));
queue_if_no_path(m, false, false, __func__);
}
/*
* Enable the queue_if_no_path timeout if necessary.
* Called with m->lock held.
*/
static void enable_nopath_timeout(struct multipath *m)
{
unsigned long queue_if_no_path_timeout =
READ_ONCE(queue_if_no_path_timeout_secs) * HZ;
lockdep_assert_held(&m->lock);
if (queue_if_no_path_timeout > 0 &&
atomic_read(&m->nr_valid_paths) == 0 &&
test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
mod_timer(&m->nopath_timer,
jiffies + queue_if_no_path_timeout);
}
}
static void disable_nopath_timeout(struct multipath *m)
{
del_timer_sync(&m->nopath_timer);
}
/*
* An event is triggered whenever a path is taken out of use.
* Includes path failure and PG bypass.
*/
static void trigger_event(struct work_struct *work)
{
struct multipath *m =
container_of(work, struct multipath, trigger_event);
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>]* ]+ ]+
*---------------------------------------------------------------*/
static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
struct dm_target *ti)
{
int r;
struct path_selector_type *pst;
unsigned ps_argc;
static const struct dm_arg _args[] = {
{0, 1024, "invalid number of path selector args"},
};
pst = dm_get_path_selector(dm_shift_arg(as));
if (!pst) {
ti->error = "unknown path selector type";
return -EINVAL;
}
r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
if (r) {
dm_put_path_selector(pst);
return -EINVAL;
}
r = pst->create(&pg->ps, ps_argc, as->argv);
if (r) {
dm_put_path_selector(pst);
ti->error = "path selector constructor failed";
return r;
}
pg->ps.type = pst;
dm_consume_args(as, ps_argc);
return 0;
}
static int setup_scsi_dh(struct block_device *bdev, struct multipath *m,
const char **attached_handler_name, char **error)
{
struct request_queue *q = bdev_get_queue(bdev);
int r;
if (mpath_double_check_test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, m)) {
retain:
if (*attached_handler_name) {
/*
* 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;
}
/*
* 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;
*attached_handler_name = NULL;
}
}
if (m->hw_handler_name) {
r = scsi_dh_attach(q, m->hw_handler_name);
if (r == -EBUSY) {
char b[BDEVNAME_SIZE];
printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
bdevname(bdev, b));
goto retain;
}
if (r < 0) {
*error = "error attaching hardware handler";
return r;
}
if (m->hw_handler_params) {
r = scsi_dh_set_params(q, m->hw_handler_params);
if (r < 0) {
*error = "unable to set hardware handler parameters";
return r;
}
}
}
return 0;
}
static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
struct dm_target *ti)
{
int r;
struct pgpath *p;
struct multipath *m = ti->private;
struct request_queue *q;
const char *attached_handler_name = NULL;
/* we need at least a path arg */
if (as->argc < 1) {
ti->error = "no device given";
return ERR_PTR(-EINVAL);
}
p = alloc_pgpath();
if (!p)
return ERR_PTR(-ENOMEM);
r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
&p->path.dev);
if (r) {
ti->error = "error getting device";
goto bad;
}
q = bdev_get_queue(p->path.dev->bdev);
attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
if (attached_handler_name || m->hw_handler_name) {
INIT_DELAYED_WORK(&p->activate_path, activate_path_work);
r = setup_scsi_dh(p->path.dev->bdev, m, &attached_handler_name, &ti->error);
kfree(attached_handler_name);
if (r) {
dm_put_device(ti, p->path.dev);
goto bad;
}
}
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);
return ERR_PTR(r);
}
static struct priority_group *parse_priority_group(struct dm_arg_set *as,
struct multipath *m)
{
static const struct dm_arg _args[] = {
{1, 1024, "invalid number of paths"},
{0, 1024, "invalid number of selector args"}
};
int r;
unsigned i, nr_selector_args, nr_args;
struct priority_group *pg;
struct dm_target *ti = m->ti;
if (as->argc < 2) {
as->argc = 0;
ti->error = "not enough priority group arguments";
return ERR_PTR(-EINVAL);
}
pg = alloc_priority_group();
if (!pg) {
ti->error = "couldn't allocate priority group";
return ERR_PTR(-ENOMEM);
}
pg->m = m;