Btrfs: remove unnecessary btrfs_mark_buffer_dirty in split_leaf

When we're not able to get enough space through splitting leaf,
we'd create a new sibling leaf instead, and it's possible that we return
 a zero-nritem sibling leaf and mark it dirty before it's in a consistent
state.  With CONFIG_BTRFS_FS_CHECK_INTEGRITY=y, the integrity check of
check_leaf will report panic due to this zero-nritem non-root leaf.

This removes the unnecessary btrfs_mark_buffer_dirty.
Reported-by: Filipe Manana <fdmanana@gmail.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ctree.c

@@ -4311,7 +4311,11 @@ static noinline int split_leaf(struct btrfs_trans_handle *trans,
 			if (path->slots[1] == 0)
 				fixup_low_keys(fs_info, path, &disk_key, 1);
 		}
-		btrfs_mark_buffer_dirty(right);
+		/*
+		 * We create a new leaf 'right' for the required ins_len and
+		 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
+		 * the content of ins_len to 'right'.
+		 */
 		return ret;
 	}