Added whiteout behavior option. ``-o whiteout=always'' is default mode

(it is established practice) and ``-o whiteout=whenneeded'' is less
disk-space using mode especially for resource restricted environments
like embedded environments. (Contributed by Ed Schouten. Thanks)

Submitted by:   Masanori Ozawa <ozawa@ongs.co.jp> (unionfs developer)
Reviewed by:    jeff, kensmith
Approved by:    re (kensmith)
MFC after:      1 week

1 files changed, 7 insertions, 0 deletions

diff --git a/sys/fs/unionfs/union.h b/sys/fs/unionfs/union.h
index 302b384..e97936d 100644
--- a/sys/fs/unionfs/union.h
+++ b/sys/fs/unionfs/union.h
@@ -45,11 +45,18 @@ typedef enum _unionfs_copymode {
 	UNIONFS_MASQUERADE
 } unionfs_copymode;
 
+/* whiteout policy of upper layer */
+typedef enum _unionfs_whitemode {
+       UNIONFS_WHITE_ALWAYS = 0,
+       UNIONFS_WHITE_WHENNEEDED
+} unionfs_whitemode;
+
 struct unionfs_mount {
 	struct vnode   *um_lowervp;	/* VREFed once */
 	struct vnode   *um_uppervp;	/* VREFed once */
 	struct vnode   *um_rootvp;	/* ROOT vnode */
 	unionfs_copymode um_copymode;
+	unionfs_whitemode um_whitemode;
 	uid_t		um_uid;
 	gid_t		um_gid;
 	u_short		um_udir;