WSL2-Linux-Kernel/drivers/md/dm-mpath.c

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34 KiB
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-path-selector.h"
#include "dm-bio-record.h"
#include "dm-uevent.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 <scsi/scsi_dh.h>
#include <asm/atomic.h>
#define DM_MSG_PREFIX "multipath"
#define MESG_STR(x) x, sizeof(x)
/* Path properties */
struct pgpath {
struct list_head list;
struct priority_group *pg; /* Owning PG */
unsigned is_active; /* Path status */
unsigned fail_count; /* Cumulative failure count */
struct dm_path path;
struct work_struct deactivate_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;
const char *hw_handler_name;
struct work_struct activate_path;
dm mpath: add missing path switching locking Moving the path activation to workqueue along with scsi_dh patches introduced a race. It is due to the fact that the current_pgpath (in the multipath data structure) can be modified if changes happen in any of the paths leading to the lun. If the changes lead to current_pgpath being set to NULL, then it leads to the invalid access which results in the panic below. This patch fixes that by storing the pgpath to activate in the multipath data structure and properly protecting it. Note that if activate_path is called twice in succession with different pgpath, with the second one being called before the first one is done, then activate path will be called twice for the second pgpath, which is fine. Unable to handle kernel paging request for data at address 0x00000020 Faulting instruction address: 0xd000000000aa1844 cpu 0x1: Vector: 300 (Data Access) at [c00000006b987a80] pc: d000000000aa1844: .activate_path+0x30/0x218 [dm_multipath] lr: c000000000087a2c: .run_workqueue+0x114/0x204 sp: c00000006b987d00 msr: 8000000000009032 dar: 20 dsisr: 40000000 current = 0xc0000000676bb3f0 paca = 0xc0000000006f3680 pid = 2528, comm = kmpath_handlerd enter ? for help [c00000006b987da0] c000000000087a2c .run_workqueue+0x114/0x204 [c00000006b987e40] c000000000088b58 .worker_thread+0x120/0x144 [c00000006b987f00] c00000000008ca70 .kthread+0x78/0xc4 [c00000006b987f90] c000000000027cc8 .kernel_thread+0x4c/0x68 Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-10-01 17:39:27 +04:00
struct pgpath *pgpath_to_activate;
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 */
unsigned pg_init_retries; /* Number of times to retry pg_init */
unsigned pg_init_count; /* Number of times pg_init called */
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 dm_mpath_io structs so that we
* can resubmit bios on error.
*/
mempool_t *mpio_pool;
};
/*
* Context information attached to each bio we process.
*/
struct dm_mpath_io {
struct pgpath *pgpath;
struct dm_bio_details details;
};
typedef int (*action_fn) (struct pgpath *pgpath);
#define MIN_IOS 256 /* Mempool size */
static struct kmem_cache *_mpio_cache;
static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
static void process_queued_ios(struct work_struct *work);
static void trigger_event(struct work_struct *work);
static void activate_path(struct work_struct *work);
static void deactivate_path(struct work_struct *work);
/*-----------------------------------------------
* Allocation routines
*-----------------------------------------------*/
static struct pgpath *alloc_pgpath(void)
{
struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
if (pgpath) {
pgpath->is_active = 1;
INIT_WORK(&pgpath->deactivate_path, deactivate_path);
}
return pgpath;
}
static void free_pgpath(struct pgpath *pgpath)
{
kfree(pgpath);
}
static void deactivate_path(struct work_struct *work)
{
struct pgpath *pgpath =
container_of(work, struct pgpath, deactivate_path);
blk_abort_queue(pgpath->path.dev->bdev->bd_disk->queue);
}
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)
{
dm mpath: add missing path switching locking Moving the path activation to workqueue along with scsi_dh patches introduced a race. It is due to the fact that the current_pgpath (in the multipath data structure) can be modified if changes happen in any of the paths leading to the lun. If the changes lead to current_pgpath being set to NULL, then it leads to the invalid access which results in the panic below. This patch fixes that by storing the pgpath to activate in the multipath data structure and properly protecting it. Note that if activate_path is called twice in succession with different pgpath, with the second one being called before the first one is done, then activate path will be called twice for the second pgpath, which is fine. Unable to handle kernel paging request for data at address 0x00000020 Faulting instruction address: 0xd000000000aa1844 cpu 0x1: Vector: 300 (Data Access) at [c00000006b987a80] pc: d000000000aa1844: .activate_path+0x30/0x218 [dm_multipath] lr: c000000000087a2c: .run_workqueue+0x114/0x204 sp: c00000006b987d00 msr: 8000000000009032 dar: 20 dsisr: 40000000 current = 0xc0000000676bb3f0 paca = 0xc0000000006f3680 pid = 2528, comm = kmpath_handlerd enter ? for help [c00000006b987da0] c000000000087a2c .run_workqueue+0x114/0x204 [c00000006b987e40] c000000000088b58 .worker_thread+0x120/0x144 [c00000006b987f00] c00000000008ca70 .kthread+0x78/0xc4 [c00000006b987f90] c000000000027cc8 .kernel_thread+0x4c/0x68 Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-10-01 17:39:27 +04:00
unsigned long flags;
struct pgpath *pgpath, *tmp;
struct multipath *m = ti->private;
list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
list_del(&pgpath->list);
if (m->hw_handler_name)
scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev));
dm_put_device(ti, pgpath->path.dev);
dm mpath: add missing path switching locking Moving the path activation to workqueue along with scsi_dh patches introduced a race. It is due to the fact that the current_pgpath (in the multipath data structure) can be modified if changes happen in any of the paths leading to the lun. If the changes lead to current_pgpath being set to NULL, then it leads to the invalid access which results in the panic below. This patch fixes that by storing the pgpath to activate in the multipath data structure and properly protecting it. Note that if activate_path is called twice in succession with different pgpath, with the second one being called before the first one is done, then activate path will be called twice for the second pgpath, which is fine. Unable to handle kernel paging request for data at address 0x00000020 Faulting instruction address: 0xd000000000aa1844 cpu 0x1: Vector: 300 (Data Access) at [c00000006b987a80] pc: d000000000aa1844: .activate_path+0x30/0x218 [dm_multipath] lr: c000000000087a2c: .run_workqueue+0x114/0x204 sp: c00000006b987d00 msr: 8000000000009032 dar: 20 dsisr: 40000000 current = 0xc0000000676bb3f0 paca = 0xc0000000006f3680 pid = 2528, comm = kmpath_handlerd enter ? for help [c00000006b987da0] c000000000087a2c .run_workqueue+0x114/0x204 [c00000006b987e40] c000000000088b58 .worker_thread+0x120/0x144 [c00000006b987f00] c00000000008ca70 .kthread+0x78/0xc4 [c00000006b987f90] c000000000027cc8 .kernel_thread+0x4c/0x68 Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-10-01 17:39:27 +04:00
spin_lock_irqsave(&m->lock, flags);
if (m->pgpath_to_activate == pgpath)
m->pgpath_to_activate = NULL;
spin_unlock_irqrestore(&m->lock, flags);
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);
m->queue_io = 1;
INIT_WORK(&m->process_queued_ios, process_queued_ios);
INIT_WORK(&m->trigger_event, trigger_event);
INIT_WORK(&m->activate_path, activate_path);
m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
if (!m->mpio_pool) {
kfree(m);
return NULL;
}
m->ti = ti;
ti->private = m;
}
return m;
}
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);
mempool_destroy(m->mpio_pool);
kfree(m);
}
/*-----------------------------------------------
* Path selection
*-----------------------------------------------*/
static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
{
m->current_pg = pgpath->pg;
/* Must we initialise the PG first, and queue I/O till it's ready? */
if (m->hw_handler_name) {
m->pg_init_required = 1;
m->queue_io = 1;
} else {
m->pg_init_required = 0;
m->queue_io = 0;
}
m->pg_init_count = 0;
}
static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg)
{
struct dm_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;
}
/*
* Check whether bios must be queued in the device-mapper core rather
* than here in the target.
*
* m->lock must be held on entry.
*
* If m->queue_if_no_path and m->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 int __must_push_back(struct multipath *m)
{
return (m->queue_if_no_path != m->saved_queue_if_no_path &&
dm_noflush_suspending(m->ti));
}
static int map_io(struct multipath *m, struct bio *bio,
struct dm_mpath_io *mpio, unsigned was_queued)
{
int r = DM_MAPIO_REMAPPED;
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 = DM_MAPIO_SUBMITTED;
} else if (pgpath)
bio->bi_bdev = pgpath->path.dev->bdev;
else if (__must_push_back(m))
r = DM_MAPIO_REQUEUE;
else
r = -EIO; /* Failed */
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 save_old_value)
{
unsigned long flags;
spin_lock_irqsave(&m->lock, flags);
if (save_old_value)
m->saved_queue_if_no_path = m->queue_if_no_path;
else
m->saved_queue_if_no_path = 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 dm_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, r);
else if (r == DM_MAPIO_REMAPPED)
generic_make_request(bio);
else if (r == DM_MAPIO_REQUEUE)
bio_endio(bio, -EIO);
bio = next;
}
}
static void process_queued_ios(struct work_struct *work)
{
struct multipath *m =
container_of(work, struct multipath, process_queued_ios);
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 && pgpath) {
m->pgpath_to_activate = pgpath;
m->pg_init_count++;
m->pg_init_required = 0;
m->pg_init_in_progress = 1;
init_required = 1;
}
out:
spin_unlock_irqrestore(&m->lock, flags);
if (init_required)
queue_work(kmpath_handlerd, &m->activate_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(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>]* ]+ ]+
*---------------------------------------------------------------*/
struct param {
unsigned min;
unsigned max;
char *error;
};
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, "invalid number of path selector args"},
};
pst = dm_get_path_selector(shift(as));
if (!pst) {
ti->error = "unknown path selector type";
return -EINVAL;
}
r = read_param(_params, shift(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;
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;
struct multipath *m = ti->private;
/* 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, shift(as), ti->begin, ti->len,
dm_table_get_mode(ti->table), &p->path.dev);
if (r) {
ti->error = "error getting device";
goto bad;
}
if (m->hw_handler_name) {
r = scsi_dh_attach(bdev_get_queue(p->path.dev->bdev),
m->hw_handler_name);
if (r < 0) {
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 arg_set *as,
struct multipath *m)
{
static struct param _params[] = {
{1, 1024, "invalid number of paths"},
{0, 1024, "invalid number of selector args"}
};
int r;
unsigned i, nr_selector_args, nr_params;
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 = 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) {
ti->error = "not enough path parameters";
goto bad;
}
path_args.argc = nr_params;
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);
consume(as, nr_params);
}
return pg;
bad:
free_priority_group(pg, ti);
return ERR_PTR(r);
}
static int parse_hw_handler(struct arg_set *as, struct multipath *m)
{
unsigned hw_argc;
struct dm_target *ti = m->ti;
static struct param _params[] = {
{0, 1024, "invalid number of hardware handler args"},
};
if (read_param(_params, shift(as), &hw_argc, &ti->error))
return -EINVAL;
if (!hw_argc)
return 0;
m->hw_handler_name = kstrdup(shift(as), GFP_KERNEL);
request_module("scsi_dh_%s", m->hw_handler_name);
if (scsi_dh_handler_exist(m->hw_handler_name) == 0) {
ti->error = "unknown hardware handler type";
kfree(m->hw_handler_name);
m->hw_handler_name = NULL;
return -EINVAL;
}
if (hw_argc > 1)
DMWARN("Ignoring user-specified arguments for "
"hardware handler \"%s\"", m->hw_handler_name);
consume(as, hw_argc - 1);
return 0;
}
static int parse_features(struct arg_set *as, struct multipath *m)
{
int r;
unsigned argc;
struct dm_target *ti = m->ti;
const char *param_name;
static struct param _params[] = {
{0, 3, "invalid number of feature args"},
{1, 50, "pg_init_retries must be between 1 and 50"},
};
r = read_param(_params, shift(as), &argc, &ti->error);
if (r)
return -EINVAL;
if (!argc)
return 0;
do {
param_name = shift(as);
argc--;
if (!strnicmp(param_name, MESG_STR("queue_if_no_path"))) {
r = queue_if_no_path(m, 1, 0);
continue;
}
if (!strnicmp(param_name, MESG_STR("pg_init_retries")) &&
(argc >= 1)) {
r = read_param(_params + 1, shift(as),
&m->pg_init_retries, &ti->error);
argc--;
continue;
}
ti->error = "Unrecognised multipath feature request";
r = -EINVAL;
} while (argc && !r);
return r;
}
static int multipath_ctr(struct dm_target *ti, unsigned int argc,
char **argv)
{
/* target parameters */
static struct param _params[] = {
{1, 1024, "invalid number of priority groups"},
{1, 1024, "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(ti);
if (!m) {
ti->error = "can't allocate multipath";
return -EINVAL;
}
r = parse_features(&as, m);
if (r)
goto bad;
r = parse_hw_handler(&as, m);
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);
if (IS_ERR(pg)) {
r = PTR_ERR(pg);
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 = "priority group count mismatch";
r = -EINVAL;
goto bad;
}
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(kmpath_handlerd);
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 dm_mpath_io *mpio;
struct multipath *m = (struct multipath *) ti->private;
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_TRANSPORT);
r = map_io(m, bio, mpio, 0);
if (r < 0 || r == DM_MAPIO_REQUEUE)
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->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 = 0;
pgpath->fail_count++;
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, m->nr_valid_paths);
schedule_work(&m->trigger_event);
queue_work(kmultipathd, &pgpath->deactivate_path);
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->is_active)
goto out;
if (!pgpath->pg->ps.type->reinstate_path) {
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->is_active = 1;
m->current_pgpath = NULL;
if (!m->nr_valid_paths++ && m->queue_size)
queue_work(kmultipathd, &m->process_queued_ios);
dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
pgpath->path.dev->name, m->nr_valid_paths);
schedule_work(&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);
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;
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);
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, 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;
}
/*
* Should we retry pg_init immediately?
*/
static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
{
unsigned long flags;
int limit_reached = 0;
spin_lock_irqsave(&m->lock, flags);
if (m->pg_init_count <= m->pg_init_retries)
m->pg_init_required = 1;
else
limit_reached = 1;
spin_unlock_irqrestore(&m->lock, flags);
return limit_reached;
}
static void pg_init_done(struct dm_path *path, int errors)
{
struct pgpath *pgpath = path_to_pgpath(path);
struct priority_group *pg = pgpath->pg;
struct multipath *m = pg->m;
unsigned long flags;
/* device or driver problems */
switch (errors) {
case SCSI_DH_OK:
break;
case SCSI_DH_NOSYS:
if (!m->hw_handler_name) {
errors = 0;
break;
}
DMERR("Cannot failover device because scsi_dh_%s was not "
"loaded.", m->hw_handler_name);
/*
* 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, 1);
break;
/* TODO: For SCSI_DH_RETRY we should wait a couple seconds */
case SCSI_DH_RETRY:
case SCSI_DH_IMM_RETRY:
case SCSI_DH_RES_TEMP_UNAVAIL:
if (pg_init_limit_reached(m, pgpath))
fail_path(pgpath);
errors = 0;
break;
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) {
DMERR("Could not failover device. Error %d.", errors);
m->current_pgpath = NULL;
m->current_pg = NULL;
} else if (!m->pg_init_required) {
m->queue_io = 0;
pg->bypassed = 0;
}
m->pg_init_in_progress = 0;
queue_work(kmultipathd, &m->process_queued_ios);
spin_unlock_irqrestore(&m->lock, flags);
}
static void activate_path(struct work_struct *work)
{
int ret;
struct multipath *m =
container_of(work, struct multipath, activate_path);
dm mpath: add missing path switching locking Moving the path activation to workqueue along with scsi_dh patches introduced a race. It is due to the fact that the current_pgpath (in the multipath data structure) can be modified if changes happen in any of the paths leading to the lun. If the changes lead to current_pgpath being set to NULL, then it leads to the invalid access which results in the panic below. This patch fixes that by storing the pgpath to activate in the multipath data structure and properly protecting it. Note that if activate_path is called twice in succession with different pgpath, with the second one being called before the first one is done, then activate path will be called twice for the second pgpath, which is fine. Unable to handle kernel paging request for data at address 0x00000020 Faulting instruction address: 0xd000000000aa1844 cpu 0x1: Vector: 300 (Data Access) at [c00000006b987a80] pc: d000000000aa1844: .activate_path+0x30/0x218 [dm_multipath] lr: c000000000087a2c: .run_workqueue+0x114/0x204 sp: c00000006b987d00 msr: 8000000000009032 dar: 20 dsisr: 40000000 current = 0xc0000000676bb3f0 paca = 0xc0000000006f3680 pid = 2528, comm = kmpath_handlerd enter ? for help [c00000006b987da0] c000000000087a2c .run_workqueue+0x114/0x204 [c00000006b987e40] c000000000088b58 .worker_thread+0x120/0x144 [c00000006b987f00] c00000000008ca70 .kthread+0x78/0xc4 [c00000006b987f90] c000000000027cc8 .kernel_thread+0x4c/0x68 Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-10-01 17:39:27 +04:00
struct dm_path *path;
unsigned long flags;
dm mpath: add missing path switching locking Moving the path activation to workqueue along with scsi_dh patches introduced a race. It is due to the fact that the current_pgpath (in the multipath data structure) can be modified if changes happen in any of the paths leading to the lun. If the changes lead to current_pgpath being set to NULL, then it leads to the invalid access which results in the panic below. This patch fixes that by storing the pgpath to activate in the multipath data structure and properly protecting it. Note that if activate_path is called twice in succession with different pgpath, with the second one being called before the first one is done, then activate path will be called twice for the second pgpath, which is fine. Unable to handle kernel paging request for data at address 0x00000020 Faulting instruction address: 0xd000000000aa1844 cpu 0x1: Vector: 300 (Data Access) at [c00000006b987a80] pc: d000000000aa1844: .activate_path+0x30/0x218 [dm_multipath] lr: c000000000087a2c: .run_workqueue+0x114/0x204 sp: c00000006b987d00 msr: 8000000000009032 dar: 20 dsisr: 40000000 current = 0xc0000000676bb3f0 paca = 0xc0000000006f3680 pid = 2528, comm = kmpath_handlerd enter ? for help [c00000006b987da0] c000000000087a2c .run_workqueue+0x114/0x204 [c00000006b987e40] c000000000088b58 .worker_thread+0x120/0x144 [c00000006b987f00] c00000000008ca70 .kthread+0x78/0xc4 [c00000006b987f90] c000000000027cc8 .kernel_thread+0x4c/0x68 Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-10-01 17:39:27 +04:00
spin_lock_irqsave(&m->lock, flags);
path = &m->pgpath_to_activate->path;
m->pgpath_to_activate = NULL;
spin_unlock_irqrestore(&m->lock, flags);
if (!path)
return;
ret = scsi_dh_activate(bdev_get_queue(path->dev->bdev));
pg_init_done(path, ret);
}
/*
* end_io handling
*/
static int do_end_io(struct multipath *m, struct bio *bio,
int error, struct dm_mpath_io *mpio)
{
unsigned long flags;
if (!error)
return 0; /* I/O complete */
if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
return error;
if (error == -EOPNOTSUPP)
return error;
spin_lock_irqsave(&m->lock, flags);
if (!m->nr_valid_paths) {
if (__must_push_back(m)) {
spin_unlock_irqrestore(&m->lock, flags);
return DM_ENDIO_REQUEUE;
} else if (!m->queue_if_no_path) {
spin_unlock_irqrestore(&m->lock, flags);
return -EIO;
} else {
spin_unlock_irqrestore(&m->lock, flags);
goto requeue;
}
}
spin_unlock_irqrestore(&m->lock, flags);
if (mpio->pgpath)
fail_path(mpio->pgpath);
requeue:
dm_bio_restore(&mpio->details, bio);
/* queue for the daemon to resubmit or fail */
spin_lock_irqsave(&m->lock, flags);
bio_list_add(&m->queued_ios, bio);
m->queue_size++;
if (!m->queue_io)
queue_work(kmultipathd, &m->process_queued_ios);
spin_unlock_irqrestore(&m->lock, flags);
return DM_ENDIO_INCOMPLETE; /* 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 = ti->private;
struct dm_mpath_io *mpio = 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 != DM_ENDIO_INCOMPLETE)
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, 1);
}
/*
* 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 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 ", m->queue_size, m->pg_init_count);
else {
DMEMIT("%u ", m->queue_if_no_path +
(m->pg_init_retries > 0) * 2);
if (m->queue_if_no_path)
DMEMIT("queue_if_no_path ");
if (m->pg_init_retries)
DMEMIT("pg_init_retries %u ", m->pg_init_retries);
}
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 = 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->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, 0);
else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path")))
return queue_if_no_path(m, 0, 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("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;
}
static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
unsigned long arg)
{
struct multipath *m = (struct multipath *) ti->private;
struct block_device *bdev = NULL;
fmode_t mode = 0;
unsigned long flags;
int r = 0;
spin_lock_irqsave(&m->lock, flags);
if (!m->current_pgpath)
__choose_pgpath(m);
if (m->current_pgpath) {
bdev = m->current_pgpath->path.dev->bdev;
mode = m->current_pgpath->path.dev->mode;
}
if (m->queue_io)
r = -EAGAIN;
else if (!bdev)
r = -EIO;
spin_unlock_irqrestore(&m->lock, flags);
return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
}
/*-----------------------------------------------------------------
* Module setup
*---------------------------------------------------------------*/
static struct target_type multipath_target = {
.name = "multipath",
.version = {1, 0, 5},
.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,
.ioctl = multipath_ioctl,
};
static int __init dm_multipath_init(void)
{
int r;
/* allocate a slab for the dm_ios */
_mpio_cache = KMEM_CACHE(dm_mpath_io, 0);
if (!_mpio_cache)
return -ENOMEM;
r = dm_register_target(&multipath_target);
if (r < 0) {
DMERR("register failed %d", r);
kmem_cache_destroy(_mpio_cache);
return -EINVAL;
}
kmultipathd = create_workqueue("kmpathd");
if (!kmultipathd) {
DMERR("failed to create workqueue kmpathd");
dm_unregister_target(&multipath_target);
kmem_cache_destroy(_mpio_cache);
return -ENOMEM;
}
/*
* 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 = create_singlethread_workqueue("kmpath_handlerd");
if (!kmpath_handlerd) {
DMERR("failed to create workqueue kmpath_handlerd");
destroy_workqueue(kmultipathd);
dm_unregister_target(&multipath_target);
kmem_cache_destroy(_mpio_cache);
return -ENOMEM;
}
DMINFO("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)
{
destroy_workqueue(kmpath_handlerd);
destroy_workqueue(kmultipathd);
dm_unregister_target(&multipath_target);
kmem_cache_destroy(_mpio_cache);
}
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");