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dm mpath: switch to using bitops for state flags
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Mechanical change that doesn't make any real effort to reduce the use of
m->lock; that will come later (once atomics are used for counters, etc).

Suggested-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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Mike Snitzer committed May 5, 2016
1 parent 813923b commit 518257b
Showing 1 changed file with 75 additions and 56 deletions.
131 changes: 75 additions & 56 deletions drivers/md/dm-mpath.c
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Original file line number Diff line number Diff line change
Expand Up @@ -83,13 +83,7 @@ struct multipath {
struct priority_group *current_pg;
struct priority_group *next_pg; /* Switch to this PG if set */

bool queue_io:1; /* Must we queue all I/O? */
bool queue_if_no_path:1; /* Queue I/O if last path fails? */
bool saved_queue_if_no_path:1; /* Saved state during suspension */
bool retain_attached_hw_handler:1; /* If there's already a hw_handler present, don't change it. */
bool pg_init_disabled:1; /* pg_init is not currently allowed */
bool pg_init_required:1; /* pg_init needs calling? */
bool pg_init_delay_retry:1; /* Delay pg_init retry? */
unsigned long flags; /* Multipath state flags */

unsigned pg_init_retries; /* Number of times to retry pg_init */
unsigned pg_init_count; /* Number of times pg_init called */
Expand Down Expand Up @@ -122,6 +116,17 @@ static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
static void trigger_event(struct work_struct *work);
static void activate_path(struct work_struct *work);

/*-----------------------------------------------
* 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
Expand Down Expand Up @@ -189,7 +194,7 @@ static struct multipath *alloc_multipath(struct dm_target *ti, bool use_blk_mq)
if (m) {
INIT_LIST_HEAD(&m->priority_groups);
spin_lock_init(&m->lock);
m->queue_io = true;
set_bit(MPATHF_QUEUE_IO, &m->flags);
m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
INIT_WORK(&m->trigger_event, trigger_event);
init_waitqueue_head(&m->pg_init_wait);
Expand Down Expand Up @@ -274,17 +279,17 @@ static int __pg_init_all_paths(struct multipath *m)
struct pgpath *pgpath;
unsigned long pg_init_delay = 0;

if (m->pg_init_in_progress || m->pg_init_disabled)
if (m->pg_init_in_progress || test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
return 0;

m->pg_init_count++;
m->pg_init_required = false;
clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);

/* Check here to reset pg_init_required */
if (!m->current_pg)
return 0;

if (m->pg_init_delay_retry)
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) {
Expand All @@ -304,11 +309,11 @@ static void __switch_pg(struct multipath *m, struct pgpath *pgpath)

/* Must we initialise the PG first, and queue I/O till it's ready? */
if (m->hw_handler_name) {
m->pg_init_required = true;
m->queue_io = true;
set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
set_bit(MPATHF_QUEUE_IO, &m->flags);
} else {
m->pg_init_required = false;
m->queue_io = false;
clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
clear_bit(MPATHF_QUEUE_IO, &m->flags);
}

m->pg_init_count = 0;
Expand Down Expand Up @@ -337,7 +342,7 @@ static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
bool bypassed = true;

if (!m->nr_valid_paths) {
m->queue_io = false;
clear_bit(MPATHF_QUEUE_IO, &m->flags);
goto failed;
}

Expand Down Expand Up @@ -365,7 +370,7 @@ static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
continue;
if (!__choose_path_in_pg(m, pg, nr_bytes)) {
if (!bypassed)
m->pg_init_delay_retry = true;
set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
return;
}
}
Expand All @@ -389,8 +394,9 @@ static void __choose_pgpath(struct multipath *m, size_t nr_bytes)
*/
static int __must_push_back(struct multipath *m)
{
return (m->queue_if_no_path ||
(m->queue_if_no_path != m->saved_queue_if_no_path &&
return (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) ||
((test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) !=
test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags)) &&
dm_noflush_suspending(m->ti)));
}

Expand All @@ -411,7 +417,7 @@ static int __multipath_map(struct dm_target *ti, struct request *clone,
spin_lock_irq(&m->lock);

/* Do we need to select a new pgpath? */
if (!m->current_pgpath || !m->queue_io)
if (!m->current_pgpath || !test_bit(MPATHF_QUEUE_IO, &m->flags))
__choose_pgpath(m, nr_bytes);

pgpath = m->current_pgpath;
Expand All @@ -420,7 +426,8 @@ static int __multipath_map(struct dm_target *ti, struct request *clone,
if (!__must_push_back(m))
r = -EIO; /* Failed */
goto out_unlock;
} else if (m->queue_io || m->pg_init_required) {
} else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
__pg_init_all_paths(m);
goto out_unlock;
}
Expand Down Expand Up @@ -503,11 +510,22 @@ static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,

spin_lock_irqsave(&m->lock, flags);

if (save_old_value)
m->saved_queue_if_no_path = m->queue_if_no_path;
if (save_old_value) {
if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
set_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
else
clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
} else {
if (queue_if_no_path)
set_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
else
clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
}
if (queue_if_no_path)
set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
else
m->saved_queue_if_no_path = queue_if_no_path;
m->queue_if_no_path = queue_if_no_path;
clear_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);

spin_unlock_irqrestore(&m->lock, flags);

if (!queue_if_no_path)
Expand Down Expand Up @@ -600,10 +618,10 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps
goto bad;
}

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

if (m->retain_attached_hw_handler) {
if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags)) {
retain:
attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
if (attached_handler_name) {
Expand Down Expand Up @@ -808,7 +826,7 @@ static int parse_features(struct dm_arg_set *as, struct multipath *m)
}

if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
m->retain_attached_hw_handler = true;
set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
continue;
}

Expand Down Expand Up @@ -944,20 +962,16 @@ static void multipath_wait_for_pg_init_completion(struct multipath *m)

static void flush_multipath_work(struct multipath *m)
{
unsigned long flags;

spin_lock_irqsave(&m->lock, flags);
m->pg_init_disabled = true;
spin_unlock_irqrestore(&m->lock, flags);
set_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
smp_mb__after_atomic();

flush_workqueue(kmpath_handlerd);
multipath_wait_for_pg_init_completion(m);
flush_workqueue(kmultipathd);
flush_work(&m->trigger_event);

spin_lock_irqsave(&m->lock, flags);
m->pg_init_disabled = false;
spin_unlock_irqrestore(&m->lock, flags);
clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
smp_mb__after_atomic();
}

static void multipath_dtr(struct dm_target *ti)
Expand Down Expand Up @@ -1152,8 +1166,8 @@ static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)

spin_lock_irqsave(&m->lock, flags);

if (m->pg_init_count <= m->pg_init_retries && !m->pg_init_disabled)
m->pg_init_required = true;
if (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;

Expand Down Expand Up @@ -1219,19 +1233,23 @@ static void pg_init_done(void *data, int errors)
m->current_pgpath = NULL;
m->current_pg = NULL;
}
} else if (!m->pg_init_required)
} else if (!test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
pg->bypassed = false;

if (--m->pg_init_in_progress)
/* Activations of other paths are still on going */
goto out;

if (m->pg_init_required) {
m->pg_init_delay_retry = delay_retry;
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;
}
m->queue_io = false;
clear_bit(MPATHF_QUEUE_IO, &m->flags);

/*
* Wake up any thread waiting to suspend.
Expand Down Expand Up @@ -1300,7 +1318,7 @@ static int do_end_io(struct multipath *m, struct request *clone,

spin_lock_irqsave(&m->lock, flags);
if (!m->nr_valid_paths) {
if (!m->queue_if_no_path) {
if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
if (!__must_push_back(m))
r = -EIO;
} else {
Expand Down Expand Up @@ -1364,11 +1382,12 @@ static void multipath_postsuspend(struct dm_target *ti)
static void multipath_resume(struct dm_target *ti)
{
struct multipath *m = 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);
if (test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags))
set_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
else
clear_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
smp_mb__after_atomic();
}

/*
Expand Down Expand Up @@ -1402,19 +1421,19 @@ static void multipath_status(struct dm_target *ti, status_type_t type,

/* Features */
if (type == STATUSTYPE_INFO)
DMEMIT("2 %u %u ", m->queue_io, m->pg_init_count);
DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO, &m->flags), m->pg_init_count);
else {
DMEMIT("%u ", m->queue_if_no_path +
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 +
m->retain_attached_hw_handler);
if (m->queue_if_no_path)
test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags));
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 (m->retain_attached_hw_handler)
if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
DMEMIT("retain_attached_hw_handler ");
}

Expand Down Expand Up @@ -1572,7 +1591,7 @@ static int multipath_prepare_ioctl(struct dm_target *ti,
__choose_pgpath(m, 0);

if (m->current_pgpath) {
if (!m->queue_io) {
if (!test_bit(MPATHF_QUEUE_IO, &m->flags)) {
*bdev = m->current_pgpath->path.dev->bdev;
*mode = m->current_pgpath->path.dev->mode;
r = 0;
Expand All @@ -1582,7 +1601,7 @@ static int multipath_prepare_ioctl(struct dm_target *ti,
}
} else {
/* No path is available */
if (m->queue_if_no_path)
if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
r = -ENOTCONN;
else
r = -EIO;
Expand All @@ -1596,7 +1615,7 @@ static int multipath_prepare_ioctl(struct dm_target *ti,
/* Path status changed, redo selection */
__choose_pgpath(m, 0);
}
if (m->pg_init_required)
if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
__pg_init_all_paths(m);
spin_unlock_irqrestore(&m->lock, flags);
dm_table_run_md_queue_async(m->ti->table);
Expand Down Expand Up @@ -1657,7 +1676,7 @@ static int multipath_busy(struct dm_target *ti)

/* pg_init in progress or no paths available */
if (m->pg_init_in_progress ||
(!m->nr_valid_paths && m->queue_if_no_path)) {
(!m->nr_valid_paths && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))) {
busy = true;
goto out;
}
Expand Down

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