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linux/drivers/md/dm-mpath.c
Gabriel Krisman Bertazi 087615bf3a dm mpath: pass IO start time to path selector 
The HST path selector needs this information to perform path
prediction. For request-based mpath, struct request's io_start_time_ns
is used, while for bio-based, use the start_time stored in dm_io.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2020-05-15 10:29:36 -04:00

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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? */
/*-----------------------------------------------
* 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)
{
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)) {
clear_bit(MPATHF_QUEUE_IO, &m->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)
set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->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()
* report the function name and line number of the function from which
* it has been invoked.
*/
#define dm_report_EIO(m) \
do { \
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)); \
} while (0)
/*
* 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);
}
/*
* 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 || !test_bit(MPATHF_QUEUE_IO, &m->flags))
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 (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
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_get_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_put_request(clone);
}
/*
* Map cloned bios (bio-based multipath)
*/
static struct pgpath *__map_bio(struct multipath *m, struct bio *bio)
{
struct pgpath *pgpath;
unsigned long flags;
bool queue_io;
/* Do we need to select a new pgpath? */
pgpath = READ_ONCE(m->current_pgpath);
if (!pgpath || !test_bit(MPATHF_QUEUE_IO, &m->flags))
pgpath = choose_pgpath(m, bio->bi_iter.bi_size);
/* MPATHF_QUEUE_IO might have been cleared by choose_pgpath. */
queue_io = test_bit(MPATHF_QUEUE_IO, &m->flags);
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 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_bio(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:
generic_make_request(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)
{
unsigned long flags;
spin_lock_irqsave(&m->lock, flags);
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));
assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags, queue_if_no_path);
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);
struct mapped_device *md = dm_table_get_md(m->ti->table);
DMWARN("queue_if_no_path timeout on %s, failing queued IO", dm_device_name(md));
queue_if_no_path(m, false, false);
}
/*
* 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 (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags)) {
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;
r = parse_path_selector(as, pg, ti);
if (r)
goto bad;
/*
* read the paths
*/
r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
if (r)
goto bad;
r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
if (r)
goto bad;
nr_args = 1 + nr_selector_args;
for (i = 0; i < pg->nr_pgpaths; i++) {
struct pgpath *pgpath;
struct dm_arg_set path_args;
if (as->argc < nr_args) {
ti->error = "not enough path parameters";
r = -EINVAL;
goto bad;
}
path_args.argc = nr_args;
path_args.argv = as->argv;
pgpath = parse_path(&path_args, &pg->ps, ti);
if (IS_ERR(pgpath)) {
r = PTR_ERR(pgpath);
goto bad;
}
pgpath->pg = pg;
list_add_tail(&pgpath->list, &pg->pgpaths);
dm_consume_args(as, nr_args);
}
return pg;
bad:
free_priority_group(pg, ti);
return ERR_PTR(r);
}
static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
{
unsigned hw_argc;
int ret;
struct dm_target *ti = m->ti;
static const struct dm_arg _args[] = {
{0, 1024, "invalid number of hardware handler args"},
};
if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
return -EINVAL;
if (!hw_argc)
return 0;
if (m->queue_mode == DM_TYPE_BIO_BASED) {
dm_consume_args(as, hw_argc);
DMERR("bio-based multipath doesn't allow hardware handler args");
return 0;
}
m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
if (!m->hw_handler_name)
return -EINVAL;
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]);
}
dm_consume_args(as, hw_argc - 1);
return 0;
fail:
kfree(m->hw_handler_name);
m->hw_handler_name = NULL;
return ret;
}
static int parse_features(struct dm_arg_set *as, struct multipath *m)
{
int r;
unsigned argc;
struct dm_target *ti = m->ti;
const char *arg_name;
static const struct dm_arg _args[] = {
{0, 8, "invalid number of feature args"},
{1, 50, "pg_init_retries must be between 1 and 50"},
{0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
};
r = dm_read_arg_group(_args, as, &argc, &ti->error);
if (r)
return -EINVAL;
if (!argc)
return 0;
do {
arg_name = dm_shift_arg(as);
argc--;
if (!strcasecmp(arg_name, "queue_if_no_path")) {
r = queue_if_no_path(m, true, false);
continue;
}
if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
continue;
}
if (!strcasecmp(arg_name, "pg_init_retries") &&
(argc >= 1)) {
r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
argc--;
continue;
}
if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
(argc >= 1)) {
r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
argc--;
continue;
}
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") ||
!strcasecmp(queue_mode_name, "mq"))
m->queue_mode = DM_TYPE_REQUEST_BASED;
else {
ti->error = "Unknown 'queue_mode' requested";
r = -EINVAL;
}
argc--;
continue;
}
ti->error = "Unrecognised multipath feature request";
r = -EINVAL;
} while (argc && !r);
return r;
}
static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
{
/* target arguments */
static const struct dm_arg _args[] = {
{0, 1024, "invalid number of priority groups"},
{0, 1024, "invalid initial priority group number"},
};
int r;
struct multipath *m;
struct dm_arg_set as;
unsigned pg_count = 0;
unsigned next_pg_num;
unsigned long flags;
as.argc = argc;
as.argv = argv;
m = alloc_multipath(ti);
if (!m) {
ti->error = "can't allocate multipath";
return -EINVAL;
}
r = parse_features(&as, m);
if (r)
goto bad;
r = alloc_multipath_stage2(ti, m);
if (r)
goto bad;
r = parse_hw_handler(&as, m);
if (r)
goto bad;
r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
if (r)
goto bad;
r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
if (r)
goto bad;
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;
}
/* parse the priority groups */
while (as.argc) {
struct priority_group *pg;
unsigned nr_valid_paths = atomic_read(&m->nr_valid_paths);
pg = parse_priority_group(&as, m);
if (IS_ERR(pg)) {
r = PTR_ERR(pg);
goto bad;
}
nr_valid_paths += pg->nr_pgpaths;
atomic_set(&m->nr_valid_paths, nr_valid_paths);
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) {
ti->error = "priority group count mismatch";
r = -EINVAL;
goto bad;
}
spin_lock_irqsave(&m->lock, flags);
enable_nopath_timeout(m);
spin_unlock_irqrestore(&m->lock, flags);
ti->num_flush_bios = 1;
ti->num_discard_bios = 1;
ti->num_write_same_bios = 1;
ti->num_write_zeroes_bios = 1;
if (m->queue_mode == DM_TYPE_BIO_BASED)
ti->per_io_data_size = multipath_per_bio_data_size();
else
ti->per_io_data_size = sizeof(struct dm_mpath_io);
return 0;
bad:
free_multipath(m);
return r;
}
static void multipath_wait_for_pg_init_completion(struct multipath *m)
{
DEFINE_WAIT(wait);
while (1) {
prepare_to_wait(&m->pg_init_wait, &wait, TASK_UNINTERRUPTIBLE);
if (!atomic_read(&m->pg_init_in_progress))
break;
io_schedule();
}
finish_wait(&m->pg_init_wait, &wait);
}
static void flush_multipath_work(struct multipath *m)
{
if (m->hw_handler_name) {
set_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
smp_mb__after_atomic();
if (atomic_read(&m->pg_init_in_progress))
flush_workqueue(kmpath_handlerd);
multipath_wait_for_pg_init_completion(m);
clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
smp_mb__after_atomic();
}
if (m->queue_mode == DM_TYPE_BIO_BASED)
flush_work(&m->process_queued_bios);
flush_work(&m->trigger_event);
}
static void multipath_dtr(struct dm_target *ti)
{
struct multipath *m = ti->private;
disable_nopath_timeout(m);
flush_multipath_work(m);
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);
if (!pgpath->is_active)
goto out;
DMWARN("Failing path %s.", pgpath->path.dev->name);
pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
pgpath->is_active = false;
pgpath->fail_count++;
atomic_dec(&m->nr_valid_paths);
if (pgpath == m->current_pgpath)
m->current_pgpath = NULL;
dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
pgpath->path.dev->name, atomic_read(&m->nr_valid_paths));
schedule_work(&m->trigger_event);
enable_nopath_timeout(m);
out:
spin_unlock_irqrestore(&m->lock, flags);
return 0;
}
/*
* Reinstate a previously-failed path
*/
static int reinstate_path(struct pgpath *pgpath)
{
int r = 0, run_queue = 0;
unsigned long flags;
struct multipath *m = pgpath->pg->m;
unsigned nr_valid_paths;
spin_lock_irqsave(&m->lock, flags);
if (pgpath->is_active)
goto out;
DMWARN("Reinstating path %s.", pgpath->path.dev->name);
r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
if (r)
goto out;
pgpath->is_active = true;
nr_valid_paths = atomic_inc_return(&m->nr_valid_paths);
if (nr_valid_paths == 1) {
m->current_pgpath = NULL;
run_queue = 1;
} else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
atomic_inc(&m->pg_init_in_progress);
}
dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
pgpath->path.dev->name, nr_valid_paths);
schedule_work(&m->trigger_event);
out:
spin_unlock_irqrestore(&m->lock, flags);
if (run_queue) {
dm_table_run_md_queue_async(m->ti->table);
process_queued_io_list(m);
}
if (pgpath->is_active)
disable_nopath_timeout(m);
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)
{
int r = -EINVAL;
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,
bool bypassed)
{
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);
schedule_work(&m->trigger_event);
}
/*
* 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;
char dummy;
if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
!m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
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) {
pg->bypassed = false;
if (--pgnum)
continue;
m->current_pgpath = NULL;
m->current_pg = NULL;
m->next_pg = pg;
}
spin_unlock_irqrestore(&m->lock, flags);
schedule_work(&m->trigger_event);
return 0;
}
/*
* Set/clear bypassed status of a PG.
* PGs are numbered upwards from 1 in the order they were declared.
*/
static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
{
struct priority_group *pg;
unsigned pgnum;
char dummy;
if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
!m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
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;
}
/*
* Should we retry pg_init immediately?
*/
static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
{
unsigned long flags;
bool limit_reached = false;
spin_lock_irqsave(&m->lock, flags);
if (atomic_read(&m->pg_init_count) <= m->pg_init_retries &&
!test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
else
limit_reached = true;
spin_unlock_irqrestore(&m->lock, flags);
return limit_reached;
}
static void pg_init_done(void *data, int errors)
{
struct pgpath *pgpath = data;
struct priority_group *pg = pgpath->pg;
struct multipath *m = pg->m;
unsigned long flags;
bool delay_retry = false;
/* device or driver problems */
switch (errors) {
case SCSI_DH_OK:
break;
case SCSI_DH_NOSYS:
if (!m->hw_handler_name) {
errors = 0;
break;
}
DMERR("Could not failover the device: Handler scsi_dh_%s "
"Error %d.", m->hw_handler_name, errors);
/*
* 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.
*/
bypass_pg(m, pg, true);
break;
case SCSI_DH_RETRY:
/* Wait before retrying. */
delay_retry = true;
/* fall through */
case SCSI_DH_IMM_RETRY:
case SCSI_DH_RES_TEMP_UNAVAIL:
if (pg_init_limit_reached(m, pgpath))
fail_path(pgpath);
errors = 0;
break;
case SCSI_DH_DEV_OFFLINED:
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) {
if (pgpath == m->current_pgpath) {
DMERR("Could not failover device. Error %d.", errors);
m->current_pgpath = NULL;
m->current_pg = NULL;
}
} else if (!test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
pg->bypassed = false;
if (atomic_dec_return(&m->pg_init_in_progress) > 0)
/* Activations of other paths are still on going */
goto out;
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);
if (__pg_init_all_paths(m))
goto out;
}
clear_bit(MPATHF_QUEUE_IO, &m->flags);
process_queued_io_list(m);
/*
* Wake up any thread waiting to suspend.
*/
wake_up(&m->pg_init_wait);
out:
spin_unlock_irqrestore(&m->lock, flags);
}
static void activate_or_offline_path(struct pgpath *pgpath)
{
struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
if (pgpath->is_active && !blk_queue_dying(q))
scsi_dh_activate(q, pg_init_done, pgpath);
else
pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
}
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);
}
static int multipath_end_io(struct dm_target *ti, struct request *clone,
blk_status_t error, union map_info *map_context)
{
struct dm_mpath_io *mpio = get_mpio(map_context);
struct pgpath *pgpath = mpio->pgpath;
int r = DM_ENDIO_DONE;
/*
* 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.
* (See drivers/md/dm-rq.c:end_clone_bio() about why the clone requests
* 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.
*/
if (error && blk_path_error(error)) {
struct multipath *m = ti->private;
if (error == BLK_STS_RESOURCE)
r = DM_ENDIO_DELAY_REQUEUE;
else
r = DM_ENDIO_REQUEUE;
if (pgpath)
fail_path(pgpath);
if (atomic_read(&m->nr_valid_paths) == 0 &&
!must_push_back_rq(m)) {
if (error == BLK_STS_IOERR)
dm_report_EIO(m);
/* complete with the original error */
r = DM_ENDIO_DONE;
}
}
if (pgpath) {
struct path_selector *ps = &pgpath->pg->ps;
if (ps->type->end_io)
ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes,
clone->io_start_time_ns);
}
return r;
}
static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
blk_status_t *error)
{
struct multipath *m = ti->private;
struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
struct pgpath *pgpath = mpio->pgpath;
unsigned long flags;
int r = DM_ENDIO_DONE;
if (!*error || !blk_path_error(*error))
goto done;
if (pgpath)
fail_path(pgpath);
if (atomic_read(&m->nr_valid_paths) == 0 &&
!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
if (must_push_back_bio(m)) {
r = DM_ENDIO_REQUEUE;
} else {
dm_report_EIO(m);
*error = BLK_STS_IOERR;
}
goto done;
}
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);
r = DM_ENDIO_INCOMPLETE;
done:
if (pgpath) {
struct path_selector *ps = &pgpath->pg->ps;
if (ps->type->end_io)
ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes,
dm_start_time_ns_from_clone(clone));
}
return r;
}
/*
* Suspend can't complete until all the I/O is processed so if
* 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.
*/
static void multipath_presuspend(struct dm_target *ti)
{
struct multipath *m = ti->private;
queue_if_no_path(m, false, true);
}
static void multipath_postsuspend(struct dm_target *ti)
{
struct multipath *m = ti->private;
mutex_lock(&m->work_mutex);
flush_multipath_work(m);
mutex_unlock(&m->work_mutex);
}
/*
* Restore the queue_if_no_path setting.
*/
static void multipath_resume(struct dm_target *ti)
{
struct multipath *m = ti->private;
unsigned long flags;
spin_lock_irqsave(&m->lock, flags);
assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags,
test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags));
spin_unlock_irqrestore(&m->lock, flags);
}
/*
* 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]* ]+ ]+
*/
static void multipath_status(struct dm_target *ti, status_type_t type,
unsigned status_flags, char *result, unsigned maxlen)
{
int sz = 0;
unsigned long flags;
struct multipath *m = ti->private;
struct priority_group *pg;
struct pgpath *p;
unsigned pg_num;
char state;
spin_lock_irqsave(&m->lock, flags);
/* Features */
if (type == STATUSTYPE_INFO)
DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO, &m->flags),
atomic_read(&m->pg_init_count));
else {
DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
(m->pg_init_retries > 0) * 2 +
(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) +
(m->queue_mode != DM_TYPE_REQUEST_BASED) * 2);
if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
DMEMIT("queue_if_no_path ");
if (m->pg_init_retries)
DMEMIT("pg_init_retries %u ", m->pg_init_retries);
if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
DMEMIT("retain_attached_hw_handler ");
if (m->queue_mode != DM_TYPE_REQUEST_BASED) {
switch(m->queue_mode) {
case DM_TYPE_BIO_BASED:
DMEMIT("queue_mode bio ");
break;
default:
WARN_ON_ONCE(true);
break;
}
}
}
if (!m->hw_handler_name || type == STATUSTYPE_INFO)
DMEMIT("0 ");
else
DMEMIT("1 %s ", m->hw_handler_name);
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
pg_num = (m->nr_priority_groups ? 1 : 0);
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,
p->is_active ? "A" : "F",
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,
char *result, unsigned maxlen)
{
int r = -EINVAL;
struct dm_dev *dev;
struct multipath *m = ti->private;
action_fn action;
unsigned long flags;
mutex_lock(&m->work_mutex);
if (dm_suspended(ti)) {
r = -EBUSY;
goto out;
}
if (argc == 1) {
if (!strcasecmp(argv[0], "queue_if_no_path")) {
r = queue_if_no_path(m, true, false);
spin_lock_irqsave(&m->lock, flags);
enable_nopath_timeout(m);
spin_unlock_irqrestore(&m->lock, flags);
goto out;
} else if (!strcasecmp(argv[0], "fail_if_no_path")) {
r = queue_if_no_path(m, false, false);
disable_nopath_timeout(m);
goto out;
}
}
if (argc != 2) {
DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
goto out;
}
if (!strcasecmp(argv[0], "disable_group")) {
r = bypass_pg_num(m, argv[1], true);
goto out;
} else if (!strcasecmp(argv[0], "enable_group")) {
r = bypass_pg_num(m, argv[1], false);
goto out;
} else if (!strcasecmp(argv[0], "switch_group")) {
r = switch_pg_num(m, argv[1]);
goto out;
} else if (!strcasecmp(argv[0], "reinstate_path"))
action = reinstate_path;
else if (!strcasecmp(argv[0], "fail_path"))
action = fail_path;
else {
DMWARN("Unrecognised multipath message received: %s", argv[0]);
goto out;
}
r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
if (r) {
DMWARN("message: error getting device %s",
argv[1]);
goto out;
}
r = action_dev(m, dev, action);
dm_put_device(ti, dev);
out:
mutex_unlock(&m->work_mutex);
return r;
}
static int multipath_prepare_ioctl(struct dm_target *ti,
struct block_device **bdev)
{
struct multipath *m = ti->private;
struct pgpath *current_pgpath;
int r;
current_pgpath = READ_ONCE(m->current_pgpath);
if (!current_pgpath || !test_bit(MPATHF_QUEUE_IO, &m->flags))
current_pgpath = choose_pgpath(m, 0);
if (current_pgpath) {
if (!test_bit(MPATHF_QUEUE_IO, &m->flags)) {
*bdev = current_pgpath->path.dev->bdev;
r = 0;
} else {
/* pg_init has not started or completed */
r = -ENOTCONN;
}
} else {
/* No path is available */
if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
r = -ENOTCONN;
else
r = -EIO;
}
if (r == -ENOTCONN) {
if (!READ_ONCE(m->current_pg)) {
/* Path status changed, redo selection */
(void) choose_pgpath(m, 0);
}
if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
pg_init_all_paths(m);
dm_table_run_md_queue_async(m->ti->table);
process_queued_io_list(m);
}
/*
* 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;
}
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) {
ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
if (ret)
goto out;
}
}
out:
return ret;
}
static int pgpath_busy(struct pgpath *pgpath)
{
struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
return blk_lld_busy(q);
}
/*
* 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)
{
bool busy = false, has_active = false;
struct multipath *m = ti->private;
struct priority_group *pg, *next_pg;
struct pgpath *pgpath;
/* pg_init in progress */
if (atomic_read(&m->pg_init_in_progress))
return true;
/* 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_REQUEST_BASED);
/* Guess which priority_group will be used at next mapping time */
pg = READ_ONCE(m->current_pg);
next_pg = READ_ONCE(m->next_pg);
if (unlikely(!READ_ONCE(m->current_pgpath) && next_pg))
pg = next_pg;
if (!pg) {
/*
* We don't know which pg will be used at next mapping time.
* We don't call choose_pgpath() here to avoid to trigger
* 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.
*/
return busy;
}
/*
* 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.
*/
busy = true;
list_for_each_entry(pgpath, &pg->pgpaths, list) {
if (pgpath->is_active) {
has_active = true;
if (!pgpath_busy(pgpath)) {
busy = false;
break;
}
}
}
if (!has_active) {
/*
* 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.
*/
busy = false;
}
return busy;
}
/*-----------------------------------------------------------------
* Module setup
*---------------------------------------------------------------*/
static struct target_type multipath_target = {
.name = "multipath",
.version = {1, 14, 0},
.features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE |
DM_TARGET_PASSES_INTEGRITY,
.module = THIS_MODULE,
.ctr = multipath_ctr,
.dtr = multipath_dtr,
.clone_and_map_rq = multipath_clone_and_map,
.release_clone_rq = multipath_release_clone,
.rq_end_io = multipath_end_io,
.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,
};
static int __init dm_multipath_init(void)
{
int r;
kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
if (!kmultipathd) {
DMERR("failed to create workqueue kmpathd");
r = -ENOMEM;
goto bad_alloc_kmultipathd;
}
/*
* 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.
*/
kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
WQ_MEM_RECLAIM);
if (!kmpath_handlerd) {
DMERR("failed to create workqueue kmpath_handlerd");
r = -ENOMEM;
goto bad_alloc_kmpath_handlerd;
}
r = dm_register_target(&multipath_target);
if (r < 0) {
DMERR("request-based register failed %d", r);
r = -EINVAL;
goto bad_register_target;
}
return 0;
bad_register_target:
destroy_workqueue(kmpath_handlerd);
bad_alloc_kmpath_handlerd:
destroy_workqueue(kmultipathd);
bad_alloc_kmultipathd:
return r;
}
static void __exit dm_multipath_exit(void)
{
destroy_workqueue(kmpath_handlerd);
destroy_workqueue(kmultipathd);
dm_unregister_target(&multipath_target);
}
module_init(dm_multipath_init);
module_exit(dm_multipath_exit);
module_param_named(queue_if_no_path_timeout_secs,
queue_if_no_path_timeout_secs, ulong, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(queue_if_no_path_timeout_secs, "No available paths queue IO timeout in seconds");
MODULE_DESCRIPTION(DM_NAME " multipath target");
MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");
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