Btrfs: Add extra checks to avoid removing extent_state from pages we can't free

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

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index cf1de75f088a..e22960e23501 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -436,6 +436,12 @@ static int btree_releasepage(struct page *page, gfp_t gfp_flags)
         struct extent_map_tree *map;
         int ret;
 
+        if (page_count(page) > 3) {
+                /* once for page->private, once for the caller, once
+                 * once for the page cache
+                 */
+                return 0;
+        }
         tree = &BTRFS_I(page->mapping->host)->io_tree;
         map = &BTRFS_I(page->mapping->host)->extent_tree;
         ret = try_release_extent_mapping(map, tree, page, gfp_flags);