[RFC v2 2/4] xfs: add verifier check for symlink with append/immutable flags

["Luis R. Rodriguez" <mcgrof@kernel.org>]

The Linux VFS does not allow a way to set append/immuttable attributes
to symlinks, this is just not possible. If this is detected we can
correct this with xfs_repair, so inform the user.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 fs/xfs/libxfs/xfs_symlink_remote.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_symlink_remote.c b/fs/xfs/libxfs/xfs_symlink_remote.c
index 5ef5f354587e..42dd81ede3d6 100644
--- a/fs/xfs/libxfs/xfs_symlink_remote.c
+++ b/fs/xfs/libxfs/xfs_symlink_remote.c
@@ -242,5 +242,10 @@ xfs_symlink_shortform_verify(
 	/* We /did/ null-terminate the buffer, right? */
 	if (*endp != 0)
 		return __this_address;
+
+	/* Immutable and append flags are not allowed on symlinks */
+	if (ip->i_d.di_flags & (XFS_DIFLAG_APPEND | XFS_DIFLAG_IMMUTABLE))
+		return __this_address;
+
 	return NULL;
 }
-- 
2.17.0