diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 9aaa544e65a9a1d933157c094d3b7be027b6de66..ea12d0ee684f62fe50986a42a5d34a414f3049be 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2756,7 +2756,6 @@ static int merge_bio(int rw, struct extent_io_tree *tree, struct page *page,
 	if (tree->ops && tree->ops->merge_bio_hook)
 		ret = tree->ops->merge_bio_hook(rw, page, offset, size, bio,
 						bio_flags);
-	BUG_ON(ret < 0);
 	return ret;
 
 }
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 01c6fca925f779c6d95449c9315b35f8f5fbbe19..f935fad17838e2e05ccd526fadc974a0a5fd1d96 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1822,6 +1822,10 @@ static void btrfs_clear_bit_hook(struct inode *inode,
 /*
  * extent_io.c merge_bio_hook, this must check the chunk tree to make sure
  * we don't create bios that span stripes or chunks
+ *
+ * return 1 if page cannot be merged to bio
+ * return 0 if page can be merged to bio
+ * return error otherwise
  */
 int btrfs_merge_bio_hook(int rw, struct page *page, unsigned long offset,
 			 size_t size, struct bio *bio,
@@ -1840,8 +1844,8 @@ int btrfs_merge_bio_hook(int rw, struct page *page, unsigned long offset,
 	map_length = length;
 	ret = btrfs_map_block(root->fs_info, rw, logical,
 			      &map_length, NULL, 0);
-	/* Will always return 0 with map_multi == NULL */
-	BUG_ON(ret < 0);
+	if (ret < 0)
+		return ret;
 	if (map_length < length + size)
 		return 1;
 	return 0;