1 files changed, 18 insertions, 1 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 6b9cff42265d..2854c824ab64 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -684,6 +684,12 @@ int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
                 __btrfs_close_devices(fs_devices);
                 free_fs_devices(fs_devices);
         }
+        /*
+         * Wait for rcu kworkers under __btrfs_close_devices
+         * to finish all blkdev_puts so device is really
+         * free when umount is done.
+         */
+        rcu_barrier();
         return ret;
 }
 
@@ -4929,7 +4935,18 @@ int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
         em = lookup_extent_mapping(em_tree, chunk_start, 1);
         read_unlock(&em_tree->lock);
 
-        BUG_ON(!em || em->start != chunk_start);
+        if (!em) {
+                printk(KERN_ERR "btrfs: couldn't find em for chunk %Lu\n",
+                       chunk_start);
+                return -EIO;
+        }
+
+        if (em->start != chunk_start) {
+                printk(KERN_ERR "btrfs: bad chunk start, em=%Lu, wanted=%Lu\n",
+                       em->start, chunk_start);
+                free_extent_map(em);
+                return -EIO;
+        }
         map = (struct map_lookup *)em->bdev;
 
         length = em->len;