dm mpath: switch to using bitops for state flags

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>

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 677ba223e2aef0217b0a9fb36735753d86a6df22..598d4a1123e0bbcad0d20dc13907bc3fc84d602a 100644 (file)
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -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 */
@@ -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
@@ -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);
@@ -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) {
@@ -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;
@@ -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;
        }
 
@@ -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;
                        }
                }
@@ -389,8 +394,9 @@ failed:
  */
 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)));
 }
 
@@ -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;
@@ -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;
        }
@@ -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)
@@ -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) {
@@ -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;
                }
 
@@ -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)
@@ -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;
 
@@ -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.
@@ -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 {
@@ -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();
 }
 
 /*
@@ -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 ");
        }
 
@@ -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;
@@ -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;
@@ -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);
@@ -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;
        }