btrfs: incorrect handling for fiemap_fill_next_extent return

fiemap_fill_next_extent returns 0 on success, -errno on error, 1 if this was
the last extent that will fit in user array. If 1 is returned, the return
value may eventually returned to user space, which should not happen, according
to manpage of ioctl.

Signed-off-by: Chengyu Song <csong84@gatech.edu>
Reviewed-by: David Sterba <dsterba@suse.cz>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
(cherry picked from commit 26e726afe01c1c82072cf23a5ed89ce25f39d9f2)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 83f4a11832929d91cfb6bb0eb1aa19fa47600349..04cca7a1ed9d71519013893f134620200985b4a4 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4486,8 +4486,11 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                }
                ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
                                              em_len, flags);
-               if (ret)
+               if (ret) {
+                       if (ret == 1)
+                               ret = 0;
                        goto out_free;
+               }
        }
 out_free:
        free_extent_map(em);