dm thin: allow pool in read-only mode to transition to read-write mode

[mirror_ubuntu-zesty-kernel.git] / drivers / md / dm-thin.c

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 0d7852e2b275602d8a64b151781f4b3411f94c71..ee29037ffc2e74633050b708718ccbe963bf20d1 100644 (file)
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -1425,6 +1425,7 @@ static void set_pool_mode(struct pool *pool, enum pool_mode mode)
                break;
 
        case PM_WRITE:
+               dm_pool_metadata_read_write(pool->pmd);
                pool->process_bio = process_bio;
                pool->process_discard = process_discard;
                pool->process_prepared_mapping = process_prepared_mapping;
@@ -1641,12 +1642,19 @@ static int bind_control_target(struct pool *pool, struct dm_target *ti)
        struct pool_c *pt = ti->private;
 
        /*
-        * We want to make sure that degraded pools are never upgraded.
+        * We want to make sure that a pool in PM_FAIL mode is never upgraded.
         */
        enum pool_mode old_mode = pool->pf.mode;
        enum pool_mode new_mode = pt->adjusted_pf.mode;
 
-       if (old_mode > new_mode)
+       /*
+        * If we were in PM_FAIL mode, rollback of metadata failed.  We're
+        * not going to recover without a thin_repair.  So we never let the
+        * pool move out of the old mode.  On the other hand a PM_READ_ONLY
+        * may have been due to a lack of metadata or data space, and may
+        * now work (ie. if the underlying devices have been resized).
+        */
+       if (old_mode == PM_FAIL)
                new_mode = old_mode;
 
        pool->ti = ti;