Btrfs: return -ENOMEM in clear_extent_bit

The btrfs releasepage function depends on ENOMEM coming
back when it is called atomic.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index a90c4a12556b..0e0fe0f6ec75 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -485,7 +485,8 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 again:
         if (!prealloc && (mask & __GFP_WAIT)) {
                 prealloc = alloc_extent_state(mask);
-                BUG_ON(!prealloc);
+                if (!prealloc)
+                        return -ENOMEM;
         }
 
         spin_lock(&tree->lock);