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>

1 files changed, 4 insertions, 1 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d688cfe5d496..782f3bc4651d 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4514,8 +4514,11 @@ 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);