linux/drivers/md/dm-mpath.c
Alasdair G Kergon c3cd4f6b27 [PATCH] device-mapper multipath: Fix pg initialisation races
Prevent more than one priority group initialisation function from being
outstanding at once.  Otherwise the completion functions interfere with each
other.  Also, reloading the table could reference a freed pointer.

Only reset queue_io in pg_init_complete if another pg_init isn't required.
Skip process_queued_ios if the queue is empty so that we only trigger a
pg_init if there's I/O.

Signed-off-by: Lars Marowsky-Bree <lmb@suse.de>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-07-12 16:19:11 -07:00

1336 lines
29 KiB
C

/*
* Copyright (C) 2003 Sistina Software Limited.
* Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
*
* This file is released under the GPL.
*/
#include "dm.h"
#include "dm-path-selector.h"
#include "dm-hw-handler.h"
#include "dm-bio-list.h"
#include "dm-bio-record.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/workqueue.h>
#include <asm/atomic.h>
#define MESG_STR(x) x, sizeof(x)
/* Path properties */
struct pgpath {
struct list_head list;
struct priority_group *pg; /* Owning PG */
unsigned fail_count; /* Cumulative failure count */
struct path path;
};
#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 bypassed; /* Temporarily bypass this PG? */
unsigned nr_pgpaths; /* Number of paths in PG */
struct list_head pgpaths;
};
/* Multipath context */
struct multipath {
struct list_head list;
struct dm_target *ti;
spinlock_t lock;
struct hw_handler hw_handler;
unsigned nr_priority_groups;
struct list_head priority_groups;
unsigned pg_init_required; /* pg_init needs calling? */
unsigned pg_init_in_progress; /* Only one pg_init allowed at once */
unsigned nr_valid_paths; /* Total number of usable paths */
struct pgpath *current_pgpath;
struct priority_group *current_pg;
struct priority_group *next_pg; /* Switch to this PG if set */
unsigned repeat_count; /* I/Os left before calling PS again */
unsigned queue_io; /* Must we queue all I/O? */
unsigned queue_if_no_path; /* Queue I/O if last path fails? */
unsigned saved_queue_if_no_path;/* Saved state during suspension */
struct work_struct process_queued_ios;
struct bio_list queued_ios;
unsigned queue_size;
struct work_struct trigger_event;
/*
* We must use a mempool of mpath_io structs so that we
* can resubmit bios on error.
*/
mempool_t *mpio_pool;
};
/*
* Context information attached to each bio we process.
*/
struct mpath_io {
struct pgpath *pgpath;
struct dm_bio_details details;
};
typedef int (*action_fn) (struct pgpath *pgpath);
#define MIN_IOS 256 /* Mempool size */
static kmem_cache_t *_mpio_cache;
struct workqueue_struct *kmultipathd;
static void process_queued_ios(void *data);
static void trigger_event(void *data);
/*-----------------------------------------------
* Allocation routines
*-----------------------------------------------*/
static struct pgpath *alloc_pgpath(void)
{
struct pgpath *pgpath = kmalloc(sizeof(*pgpath), GFP_KERNEL);
if (pgpath) {
memset(pgpath, 0, sizeof(*pgpath));
pgpath->path.is_active = 1;
}
return pgpath;
}
static inline void free_pgpath(struct pgpath *pgpath)
{
kfree(pgpath);
}
static struct priority_group *alloc_priority_group(void)
{
struct priority_group *pg;
pg = kmalloc(sizeof(*pg), GFP_KERNEL);
if (!pg)
return NULL;
memset(pg, 0, sizeof(*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(void)
{
struct multipath *m;
m = kmalloc(sizeof(*m), GFP_KERNEL);
if (m) {
memset(m, 0, sizeof(*m));
INIT_LIST_HEAD(&m->priority_groups);
spin_lock_init(&m->lock);
m->queue_io = 1;
INIT_WORK(&m->process_queued_ios, process_queued_ios, m);
INIT_WORK(&m->trigger_event, trigger_event, m);
m->mpio_pool = mempool_create(MIN_IOS, mempool_alloc_slab,
mempool_free_slab, _mpio_cache);
if (!m->mpio_pool) {
kfree(m);
return NULL;
}
}
return m;
}
static void free_multipath(struct multipath *m)
{
struct priority_group *pg, *tmp;
struct hw_handler *hwh = &m->hw_handler;
list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
list_del(&pg->list);
free_priority_group(pg, m->ti);
}
if (hwh->type) {
hwh->type->destroy(hwh);
dm_put_hw_handler(hwh->type);
}
mempool_destroy(m->mpio_pool);
kfree(m);
}
/*-----------------------------------------------
* Path selection
*-----------------------------------------------*/
static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
{
struct hw_handler *hwh = &m->hw_handler;
m->current_pg = pgpath->pg;
/* Must we initialise the PG first, and queue I/O till it's ready? */
if (hwh->type && hwh->type->pg_init) {
m->pg_init_required = 1;
m->queue_io = 1;
} else {
m->pg_init_required = 0;
m->queue_io = 0;
}
}
static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg)
{
struct path *path;
path = pg->ps.type->select_path(&pg->ps, &m->repeat_count);
if (!path)
return -ENXIO;
m->current_pgpath = path_to_pgpath(path);
if (m->current_pg != pg)
__switch_pg(m, m->current_pgpath);
return 0;
}
static void __choose_pgpath(struct multipath *m)
{
struct priority_group *pg;
unsigned bypassed = 1;
if (!m->nr_valid_paths)
goto failed;
/* Were we instructed to switch PG? */
if (m->next_pg) {
pg = m->next_pg;
m->next_pg = NULL;
if (!__choose_path_in_pg(m, pg))
return;
}
/* Don't change PG until it has no remaining paths */
if (m->current_pg && !__choose_path_in_pg(m, m->current_pg))
return;
/*
* 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.
*/
do {
list_for_each_entry(pg, &m->priority_groups, list) {
if (pg->bypassed == bypassed)
continue;
if (!__choose_path_in_pg(m, pg))
return;
}
} while (bypassed--);
failed:
m->current_pgpath = NULL;
m->current_pg = NULL;
}
static int map_io(struct multipath *m, struct bio *bio, struct mpath_io *mpio,
unsigned was_queued)
{
int r = 1;
unsigned long flags;
struct pgpath *pgpath;
spin_lock_irqsave(&m->lock, flags);
/* Do we need to select a new pgpath? */
if (!m->current_pgpath ||
(!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
__choose_pgpath(m);
pgpath = m->current_pgpath;
if (was_queued)
m->queue_size--;
if ((pgpath && m->queue_io) ||
(!pgpath && m->queue_if_no_path)) {
/* Queue for the daemon to resubmit */
bio_list_add(&m->queued_ios, bio);
m->queue_size++;
if ((m->pg_init_required && !m->pg_init_in_progress) ||
!m->queue_io)
queue_work(kmultipathd, &m->process_queued_ios);
pgpath = NULL;
r = 0;
} else if (!pgpath)
r = -EIO; /* Failed */
else
bio->bi_bdev = pgpath->path.dev->bdev;
mpio->pgpath = pgpath;
spin_unlock_irqrestore(&m->lock, flags);
return r;
}
/*
* If we run out of usable paths, should we queue I/O or error it?
*/
static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path)
{
unsigned long flags;
spin_lock_irqsave(&m->lock, flags);
m->saved_queue_if_no_path = m->queue_if_no_path;
m->queue_if_no_path = queue_if_no_path;
if (!m->queue_if_no_path && m->queue_size)
queue_work(kmultipathd, &m->process_queued_ios);
spin_unlock_irqrestore(&m->lock, flags);
return 0;
}
/*-----------------------------------------------------------------
* The multipath daemon is responsible for resubmitting queued ios.
*---------------------------------------------------------------*/
static void dispatch_queued_ios(struct multipath *m)
{
int r;
unsigned long flags;
struct bio *bio = NULL, *next;
struct mpath_io *mpio;
union map_info *info;
spin_lock_irqsave(&m->lock, flags);
bio = bio_list_get(&m->queued_ios);
spin_unlock_irqrestore(&m->lock, flags);
while (bio) {
next = bio->bi_next;
bio->bi_next = NULL;
info = dm_get_mapinfo(bio);
mpio = info->ptr;
r = map_io(m, bio, mpio, 1);
if (r < 0)
bio_endio(bio, bio->bi_size, r);
else if (r == 1)
generic_make_request(bio);
bio = next;
}
}
static void process_queued_ios(void *data)
{
struct multipath *m = (struct multipath *) data;
struct hw_handler *hwh = &m->hw_handler;
struct pgpath *pgpath = NULL;
unsigned init_required = 0, must_queue = 1;
unsigned long flags;
spin_lock_irqsave(&m->lock, flags);
if (!m->queue_size)
goto out;
if (!m->current_pgpath)
__choose_pgpath(m);
pgpath = m->current_pgpath;
if ((pgpath && !m->queue_io) ||
(!pgpath && !m->queue_if_no_path))
must_queue = 0;
if (m->pg_init_required && !m->pg_init_in_progress) {
m->pg_init_required = 0;
m->pg_init_in_progress = 1;
init_required = 1;
}
out:
spin_unlock_irqrestore(&m->lock, flags);
if (init_required)
hwh->type->pg_init(hwh, pgpath->pg->bypassed, &pgpath->path);
if (!must_queue)
dispatch_queued_ios(m);
}
/*
* An event is triggered whenever a path is taken out of use.
* Includes path failure and PG bypass.
*/
static void trigger_event(void *data)
{
struct multipath *m = (struct multipath *) data;
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>]* ]+ ]+
*---------------------------------------------------------------*/
struct param {
unsigned min;
unsigned max;
char *error;
};
#define ESTR(s) ("dm-multipath: " s)
static int read_param(struct param *param, char *str, unsigned *v, char **error)
{
if (!str ||
(sscanf(str, "%u", v) != 1) ||
(*v < param->min) ||
(*v > param->max)) {
*error = param->error;
return -EINVAL;
}
return 0;
}
struct arg_set {
unsigned argc;
char **argv;
};
static char *shift(struct arg_set *as)
{
char *r;
if (as->argc) {
as->argc--;
r = *as->argv;
as->argv++;
return r;
}
return NULL;
}
static void consume(struct arg_set *as, unsigned n)
{
BUG_ON (as->argc < n);
as->argc -= n;
as->argv += n;
}
static int parse_path_selector(struct arg_set *as, struct priority_group *pg,
struct dm_target *ti)
{
int r;
struct path_selector_type *pst;
unsigned ps_argc;
static struct param _params[] = {
{0, 1024, ESTR("invalid number of path selector args")},
};
pst = dm_get_path_selector(shift(as));
if (!pst) {
ti->error = ESTR("unknown path selector type");
return -EINVAL;
}
r = read_param(_params, shift(as), &ps_argc, &ti->error);
if (r)
return -EINVAL;
r = pst->create(&pg->ps, ps_argc, as->argv);
if (r) {
dm_put_path_selector(pst);
ti->error = ESTR("path selector constructor failed");
return r;
}
pg->ps.type = pst;
consume(as, ps_argc);
return 0;
}
static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
struct dm_target *ti)
{
int r;
struct pgpath *p;
/* we need at least a path arg */
if (as->argc < 1) {
ti->error = ESTR("no device given");
return NULL;
}
p = alloc_pgpath();
if (!p)
return NULL;
r = dm_get_device(ti, shift(as), ti->begin, ti->len,
dm_table_get_mode(ti->table), &p->path.dev);
if (r) {
ti->error = ESTR("error getting device");
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 NULL;
}
static struct priority_group *parse_priority_group(struct arg_set *as,
struct multipath *m,
struct dm_target *ti)
{
static struct param _params[] = {
{1, 1024, ESTR("invalid number of paths")},
{0, 1024, ESTR("invalid number of selector args")}
};
int r;
unsigned i, nr_selector_args, nr_params;
struct priority_group *pg;
if (as->argc < 2) {
as->argc = 0;
ti->error = ESTR("not enough priority group aruments");
return NULL;
}
pg = alloc_priority_group();
if (!pg) {
ti->error = ESTR("couldn't allocate priority group");
return NULL;
}
pg->m = m;
r = parse_path_selector(as, pg, ti);
if (r)
goto bad;
/*
* read the paths
*/
r = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error);
if (r)
goto bad;
r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error);
if (r)
goto bad;
nr_params = 1 + nr_selector_args;
for (i = 0; i < pg->nr_pgpaths; i++) {
struct pgpath *pgpath;
struct arg_set path_args;
if (as->argc < nr_params)
goto bad;
path_args.argc = nr_params;
path_args.argv = as->argv;
pgpath = parse_path(&path_args, &pg->ps, ti);
if (!pgpath)
goto bad;
pgpath->pg = pg;
list_add_tail(&pgpath->list, &pg->pgpaths);
consume(as, nr_params);
}
return pg;
bad:
free_priority_group(pg, ti);
return NULL;
}
static int parse_hw_handler(struct arg_set *as, struct multipath *m,
struct dm_target *ti)
{
int r;
struct hw_handler_type *hwht;
unsigned hw_argc;
static struct param _params[] = {
{0, 1024, ESTR("invalid number of hardware handler args")},
};
r = read_param(_params, shift(as), &hw_argc, &ti->error);
if (r)
return -EINVAL;
if (!hw_argc)
return 0;
hwht = dm_get_hw_handler(shift(as));
if (!hwht) {
ti->error = ESTR("unknown hardware handler type");
return -EINVAL;
}
r = hwht->create(&m->hw_handler, hw_argc - 1, as->argv);
if (r) {
dm_put_hw_handler(hwht);
ti->error = ESTR("hardware handler constructor failed");
return r;
}
m->hw_handler.type = hwht;
consume(as, hw_argc - 1);
return 0;
}
static int parse_features(struct arg_set *as, struct multipath *m,
struct dm_target *ti)
{
int r;
unsigned argc;
static struct param _params[] = {
{0, 1, ESTR("invalid number of feature args")},
};
r = read_param(_params, shift(as), &argc, &ti->error);
if (r)
return -EINVAL;
if (!argc)
return 0;
if (!strnicmp(shift(as), MESG_STR("queue_if_no_path")))
return queue_if_no_path(m, 1);
else {
ti->error = "Unrecognised multipath feature request";
return -EINVAL;
}
}
static int multipath_ctr(struct dm_target *ti, unsigned int argc,
char **argv)
{
/* target parameters */
static struct param _params[] = {
{1, 1024, ESTR("invalid number of priority groups")},
{1, 1024, ESTR("invalid initial priority group number")},
};
int r;
struct multipath *m;
struct arg_set as;
unsigned pg_count = 0;
unsigned next_pg_num;
as.argc = argc;
as.argv = argv;
m = alloc_multipath();
if (!m) {
ti->error = ESTR("can't allocate multipath");
return -EINVAL;
}
r = parse_features(&as, m, ti);
if (r)
goto bad;
r = parse_hw_handler(&as, m, ti);
if (r)
goto bad;
r = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error);
if (r)
goto bad;
r = read_param(_params + 1, shift(&as), &next_pg_num, &ti->error);
if (r)
goto bad;
/* parse the priority groups */
while (as.argc) {
struct priority_group *pg;
pg = parse_priority_group(&as, m, ti);
if (!pg) {
r = -EINVAL;
goto bad;
}
m->nr_valid_paths += pg->nr_pgpaths;
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 = ESTR("priority group count mismatch");
r = -EINVAL;
goto bad;
}
ti->private = m;
m->ti = ti;
return 0;
bad:
free_multipath(m);
return r;
}
static void multipath_dtr(struct dm_target *ti)
{
struct multipath *m = (struct multipath *) ti->private;
flush_workqueue(kmultipathd);
free_multipath(m);
}
/*
* Map bios, recording original fields for later in case we have to resubmit
*/
static int multipath_map(struct dm_target *ti, struct bio *bio,
union map_info *map_context)
{
int r;
struct mpath_io *mpio;
struct multipath *m = (struct multipath *) ti->private;
if (bio_barrier(bio))
return -EOPNOTSUPP;
mpio = mempool_alloc(m->mpio_pool, GFP_NOIO);
dm_bio_record(&mpio->details, bio);
map_context->ptr = mpio;
bio->bi_rw |= (1 << BIO_RW_FAILFAST);
r = map_io(m, bio, mpio, 0);
if (r < 0)
mempool_free(mpio, m->mpio_pool);
return r;
}
/*
* 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->path.is_active)
goto out;
DMWARN("dm-multipath: Failing path %s.", pgpath->path.dev->name);
pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
pgpath->path.is_active = 0;
pgpath->fail_count++;
m->nr_valid_paths--;
if (pgpath == m->current_pgpath)
m->current_pgpath = NULL;
queue_work(kmultipathd, &m->trigger_event);
out:
spin_unlock_irqrestore(&m->lock, flags);
return 0;
}
/*
* Reinstate a previously-failed path
*/
static int reinstate_path(struct pgpath *pgpath)
{
int r = 0;
unsigned long flags;
struct multipath *m = pgpath->pg->m;
spin_lock_irqsave(&m->lock, flags);
if (pgpath->path.is_active)
goto out;
if (!pgpath->pg->ps.type) {
DMWARN("Reinstate path not supported by path selector %s",
pgpath->pg->ps.type->name);
r = -EINVAL;
goto out;
}
r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
if (r)
goto out;
pgpath->path.is_active = 1;
m->current_pgpath = NULL;
if (!m->nr_valid_paths++ && m->queue_size)
queue_work(kmultipathd, &m->process_queued_ios);
queue_work(kmultipathd, &m->trigger_event);
out:
spin_unlock_irqrestore(&m->lock, flags);
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 = 0;
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,
int 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);
queue_work(kmultipathd, &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;
if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
(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 = 0;
if (--pgnum)
continue;
m->current_pgpath = NULL;
m->current_pg = NULL;
m->next_pg = pg;
}
spin_unlock_irqrestore(&m->lock, flags);
queue_work(kmultipathd, &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, int bypassed)
{
struct priority_group *pg;
unsigned pgnum;
if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
(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;
}
/*
* pg_init must call this when it has completed its initialisation
*/
void dm_pg_init_complete(struct path *path, unsigned err_flags)
{
struct pgpath *pgpath = path_to_pgpath(path);
struct priority_group *pg = pgpath->pg;
struct multipath *m = pg->m;
unsigned long flags;
/* We insist on failing the path if the PG is already bypassed. */
if (err_flags && pg->bypassed)
err_flags |= MP_FAIL_PATH;
if (err_flags & MP_FAIL_PATH)
fail_path(pgpath);
if (err_flags & MP_BYPASS_PG)
bypass_pg(m, pg, 1);
spin_lock_irqsave(&m->lock, flags);
if (err_flags) {
m->current_pgpath = NULL;
m->current_pg = NULL;
} else if (!m->pg_init_required)
m->queue_io = 0;
m->pg_init_in_progress = 0;
queue_work(kmultipathd, &m->process_queued_ios);
spin_unlock_irqrestore(&m->lock, flags);
}
/*
* end_io handling
*/
static int do_end_io(struct multipath *m, struct bio *bio,
int error, struct mpath_io *mpio)
{
struct hw_handler *hwh = &m->hw_handler;
unsigned err_flags = MP_FAIL_PATH; /* Default behavior */
if (!error)
return 0; /* I/O complete */
if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
return error;
if (error == -EOPNOTSUPP)
return error;
spin_lock(&m->lock);
if (!m->nr_valid_paths) {
if (!m->queue_if_no_path) {
spin_unlock(&m->lock);
return -EIO;
} else {
spin_unlock(&m->lock);
goto requeue;
}
}
spin_unlock(&m->lock);
if (hwh->type && hwh->type->error)
err_flags = hwh->type->error(hwh, bio);
if (mpio->pgpath) {
if (err_flags & MP_FAIL_PATH)
fail_path(mpio->pgpath);
if (err_flags & MP_BYPASS_PG)
bypass_pg(m, mpio->pgpath->pg, 1);
}
if (err_flags & MP_ERROR_IO)
return -EIO;
requeue:
dm_bio_restore(&mpio->details, bio);
/* queue for the daemon to resubmit or fail */
spin_lock(&m->lock);
bio_list_add(&m->queued_ios, bio);
m->queue_size++;
if (!m->queue_io)
queue_work(kmultipathd, &m->process_queued_ios);
spin_unlock(&m->lock);
return 1; /* io not complete */
}
static int multipath_end_io(struct dm_target *ti, struct bio *bio,
int error, union map_info *map_context)
{
struct multipath *m = (struct multipath *) ti->private;
struct mpath_io *mpio = (struct mpath_io *) map_context->ptr;
struct pgpath *pgpath = mpio->pgpath;
struct path_selector *ps;
int r;
r = do_end_io(m, bio, error, mpio);
if (pgpath) {
ps = &pgpath->pg->ps;
if (ps->type->end_io)
ps->type->end_io(ps, &pgpath->path);
}
if (r <= 0)
mempool_free(mpio, m->mpio_pool);
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 = (struct multipath *) ti->private;
queue_if_no_path(m, 0);
}
/*
* Restore the queue_if_no_path setting.
*/
static void multipath_resume(struct dm_target *ti)
{
struct multipath *m = (struct multipath *) ti->private;
unsigned long flags;
spin_lock_irqsave(&m->lock, flags);
m->queue_if_no_path = m->saved_queue_if_no_path;
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 int multipath_status(struct dm_target *ti, status_type_t type,
char *result, unsigned int maxlen)
{
int sz = 0;
unsigned long flags;
struct multipath *m = (struct multipath *) ti->private;
struct hw_handler *hwh = &m->hw_handler;
struct priority_group *pg;
struct pgpath *p;
unsigned pg_num;
char state;
spin_lock_irqsave(&m->lock, flags);
/* Features */
if (type == STATUSTYPE_INFO)
DMEMIT("1 %u ", m->queue_size);
else if (m->queue_if_no_path)
DMEMIT("1 queue_if_no_path ");
else
DMEMIT("0 ");
if (hwh->type && hwh->type->status)
sz += hwh->type->status(hwh, type, result + sz, maxlen - sz);
else if (!hwh->type || type == STATUSTYPE_INFO)
DMEMIT("0 ");
else
DMEMIT("1 %s ", hwh->type->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 = 1;
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->path.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);
return 0;
}
static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
{
int r;
struct dm_dev *dev;
struct multipath *m = (struct multipath *) ti->private;
action_fn action;
if (argc == 1) {
if (!strnicmp(argv[0], MESG_STR("queue_if_no_path")))
return queue_if_no_path(m, 1);
else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path")))
return queue_if_no_path(m, 0);
}
if (argc != 2)
goto error;
if (!strnicmp(argv[0], MESG_STR("disable_group")))
return bypass_pg_num(m, argv[1], 1);
else if (!strnicmp(argv[0], MESG_STR("enable_group")))
return bypass_pg_num(m, argv[1], 0);
else if (!strnicmp(argv[0], MESG_STR("switch_group")))
return switch_pg_num(m, argv[1]);
else if (!strnicmp(argv[0], MESG_STR("reinstate_path")))
action = reinstate_path;
else if (!strnicmp(argv[0], MESG_STR("fail_path")))
action = fail_path;
else
goto error;
r = dm_get_device(ti, argv[1], ti->begin, ti->len,
dm_table_get_mode(ti->table), &dev);
if (r) {
DMWARN("dm-multipath message: error getting device %s",
argv[1]);
return -EINVAL;
}
r = action_dev(m, dev, action);
dm_put_device(ti, dev);
return r;
error:
DMWARN("Unrecognised multipath message received.");
return -EINVAL;
}
/*-----------------------------------------------------------------
* Module setup
*---------------------------------------------------------------*/
static struct target_type multipath_target = {
.name = "multipath",
.version = {1, 0, 4},
.module = THIS_MODULE,
.ctr = multipath_ctr,
.dtr = multipath_dtr,
.map = multipath_map,
.end_io = multipath_end_io,
.presuspend = multipath_presuspend,
.resume = multipath_resume,
.status = multipath_status,
.message = multipath_message,
};
static int __init dm_multipath_init(void)
{
int r;
/* allocate a slab for the dm_ios */
_mpio_cache = kmem_cache_create("dm_mpath", sizeof(struct mpath_io),
0, 0, NULL, NULL);
if (!_mpio_cache)
return -ENOMEM;
r = dm_register_target(&multipath_target);
if (r < 0) {
DMERR("%s: register failed %d", multipath_target.name, r);
kmem_cache_destroy(_mpio_cache);
return -EINVAL;
}
kmultipathd = create_workqueue("kmpathd");
if (!kmultipathd) {
DMERR("%s: failed to create workqueue kmpathd",
multipath_target.name);
dm_unregister_target(&multipath_target);
kmem_cache_destroy(_mpio_cache);
return -ENOMEM;
}
DMINFO("dm-multipath version %u.%u.%u loaded",
multipath_target.version[0], multipath_target.version[1],
multipath_target.version[2]);
return r;
}
static void __exit dm_multipath_exit(void)
{
int r;
destroy_workqueue(kmultipathd);
r = dm_unregister_target(&multipath_target);
if (r < 0)
DMERR("%s: target unregister failed %d",
multipath_target.name, r);
kmem_cache_destroy(_mpio_cache);
}
EXPORT_SYMBOL_GPL(dm_pg_init_complete);
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");