dm thin: suspend/resume active thin devices when reloading thin-pool

Before this change it was expected that userspace would first suspend
all active thin devices, reload/resize the thin-pool target, then resume
all active thin devices.  Now the thin-pool suspend/resume will trigger
the suspend/resume of all active thins via appropriate calls to
dm_internal_suspend and dm_internal_resume.

Store the mapped_device for each thin device in struct thin_c to make
these calls possible.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index f1b53e3..e9e9584 100644 (file)
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -292,6 +292,8 @@ struct thin_c {
 
        struct pool *pool;
        struct dm_thin_device *td;
+       struct mapped_device *thin_md;
+
        bool requeue_mode:1;
        spinlock_t lock;
        struct list_head deferred_cells;
@@ -3113,19 +3115,48 @@ static int pool_preresume(struct dm_target *ti)
        return 0;
 }
 
+static void pool_suspend_active_thins(struct pool *pool)
+{
+       struct thin_c *tc;
+
+       /* Suspend all active thin devices */
+       tc = get_first_thin(pool);
+       while (tc) {
+               dm_internal_suspend_noflush(tc->thin_md);
+               tc = get_next_thin(pool, tc);
+       }
+}
+
+static void pool_resume_active_thins(struct pool *pool)
+{
+       struct thin_c *tc;
+
+       /* Resume all active thin devices */
+       tc = get_first_thin(pool);
+       while (tc) {
+               dm_internal_resume(tc->thin_md);
+               tc = get_next_thin(pool, tc);
+       }
+}
+
 static void pool_resume(struct dm_target *ti)
 {
        struct pool_c *pt = ti->private;
        struct pool *pool = pt->pool;
        unsigned long flags;
 
+       /*
+        * Must requeue active_thins' bios and then resume
+        * active_thins _before_ clearing 'suspend' flag.
+        */
+       requeue_bios(pool);
+       pool_resume_active_thins(pool);
+
        spin_lock_irqsave(&pool->lock, flags);
        pool->low_water_triggered = false;
        pool->suspended = false;
        spin_unlock_irqrestore(&pool->lock, flags);
 
-       requeue_bios(pool);
-
        do_waker(&pool->waker.work);
 }
 
@@ -3138,6 +3169,8 @@ static void pool_presuspend(struct dm_target *ti)
        spin_lock_irqsave(&pool->lock, flags);
        pool->suspended = true;
        spin_unlock_irqrestore(&pool->lock, flags);
+
+       pool_suspend_active_thins(pool);
 }
 
 static void pool_presuspend_undo(struct dm_target *ti)
@@ -3146,6 +3179,8 @@ static void pool_presuspend_undo(struct dm_target *ti)
        struct pool *pool = pt->pool;
        unsigned long flags;
 
+       pool_resume_active_thins(pool);
+
        spin_lock_irqsave(&pool->lock, flags);
        pool->suspended = false;
        spin_unlock_irqrestore(&pool->lock, flags);
@@ -3703,6 +3738,7 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
                r = -ENOMEM;
                goto out_unlock;
        }
+       tc->thin_md = dm_table_get_md(ti->table);
        spin_lock_init(&tc->lock);
        INIT_LIST_HEAD(&tc->deferred_cells);
        bio_list_init(&tc->deferred_bio_list);