ovl: fix workdir creation

BugLink: http://bugs.launchpad.net/bugs/1624037

commit e1ff3dd1 upstream.

Workdir creation fails in latest kernel.

Fix by allowing EOPNOTSUPP as a valid return value from
vfs_removexattr(XATTR_NAME_POSIX_ACL_*).  Upper filesystem may not support
ACL and still be perfectly able to support overlayfs.
Reported-by: Martin Ziegler <ziegler@uni-freiburg.de>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: c11b9fdd ("ovl: remove posix_acl_default from workdir")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

fs/overlayfs/super.c

@@ -868,11 +868,11 @@ static struct dentry *ovl_workdir_create(struct vfsmount *mnt,
 			goto out_dput;
 
 		err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_DEFAULT);
-		if (err && err != -ENODATA)
+		if (err && err != -ENODATA && err != -EOPNOTSUPP)
 			goto out_dput;
 
 		err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_ACCESS);
-		if (err && err != -ENODATA)
+		if (err && err != -ENODATA && err != -EOPNOTSUPP)
 			goto out_dput;
 
 		/* Clear any inherited mode bits */