ovl: Fix OVL_XATTR_PREFIX

Make sure ovl_own_xattr_handler only matches attribute names starting
with "overlay.", not "overlayXXX".
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Fixes: d837a49b ("ovl: fix POSIX ACL setting")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/inode.c

@@ -194,9 +194,8 @@ static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
 
 bool ovl_is_private_xattr(const char *name)
 {
-#define OVL_XATTR_PRE_NAME OVL_XATTR_PREFIX "."
-	return strncmp(name, OVL_XATTR_PRE_NAME,
-		       sizeof(OVL_XATTR_PRE_NAME) - 1) == 0;
+	return strncmp(name, OVL_XATTR_PREFIX,
+		       sizeof(OVL_XATTR_PREFIX) - 1) == 0;
 }
 
 int ovl_setxattr(struct dentry *dentry, struct inode *inode,

fs/overlayfs/overlayfs.h

@@ -24,8 +24,8 @@ enum ovl_path_type {
 	(OVL_TYPE_MERGE(type) || !OVL_TYPE_UPPER(type))
 
 
-#define OVL_XATTR_PREFIX XATTR_TRUSTED_PREFIX "overlay"
-#define OVL_XATTR_OPAQUE OVL_XATTR_PREFIX ".opaque"
+#define OVL_XATTR_PREFIX XATTR_TRUSTED_PREFIX "overlay."
+#define OVL_XATTR_OPAQUE OVL_XATTR_PREFIX "opaque"
 
 #define OVL_ISUPPER_MASK 1UL