aufs: white-out 2/2, diropq

The marker to represent that the directory is opaque (stop digging
down the branch stack) is implemented as a special whiteout.

See also the document in previous commit.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

fs/aufs/debug.c

@@ -138,9 +138,9 @@ void au_dpri_dentry(struct dentry *dentry)
 	dinfo = au_di(dentry);
 	if (!dinfo)
 		return;
-	dpri("d-1: btop %d, bbot %d, bwh %d, gen %d\n",
+	dpri("d-1: btop %d, bbot %d, bwh %d, bdiropq %d, gen %d\n",
 	     dinfo->di_btop, dinfo->di_bbot,
-	     dinfo->di_bwh, au_digen(dentry));
+	     dinfo->di_bwh, dinfo->di_bdiropq, au_digen(dentry));
 	if (dinfo->di_btop < 0)
 		return;
 	for (bindex = dinfo->di_btop; bindex <= dinfo->di_bbot; bindex++)

fs/aufs/dentry.h

@@ -24,7 +24,7 @@ struct au_dinfo {
 	atomic_t		di_generation;
 
 	struct au_rwsem		di_rwsem;
-	aufs_bindex_t		di_btop, di_bbot, di_bwh;
+	aufs_bindex_t		di_btop, di_bbot, di_bwh, di_bdiropq;
 	struct au_hdentry	*di_hdentry;
 	struct rcu_head		rcu;
 } ____cacheline_aligned_in_smp;
@@ -46,6 +46,8 @@ void di_write_lock(struct dentry *d, unsigned int lsc);
 void di_write_unlock(struct dentry *d);
 
 struct dentry *au_h_dptr(struct dentry *dentry, aufs_bindex_t bindex);
+aufs_bindex_t au_dbtail(struct dentry *dentry);
+aufs_bindex_t au_dbtaildir(struct dentry *dentry);
 
 void au_set_h_dptr(struct dentry *dentry, aufs_bindex_t bindex,
 		   struct dentry *h_dentry);
@@ -153,6 +155,12 @@ static inline aufs_bindex_t au_dbwh(struct dentry *dentry)
 	return au_di(dentry)->di_bwh;
 }
 
+static inline aufs_bindex_t au_dbdiropq(struct dentry *dentry)
+{
+	DiMustAnyLock(dentry);
+	return au_di(dentry)->di_bdiropq;
+}
+
 /* todo: hard/soft set? */
 static inline void au_set_dbtop(struct dentry *dentry, aufs_bindex_t bindex)
 {
@@ -173,5 +181,11 @@ static inline void au_set_dbwh(struct dentry *dentry, aufs_bindex_t bindex)
 	au_di(dentry)->di_bwh = bindex;
 }
 
+static inline void au_set_dbdiropq(struct dentry *dentry, aufs_bindex_t bindex)
+{
+	DiMustWriteLock(dentry);
+	au_di(dentry)->di_bdiropq = bindex;
+}
+
 #endif /* __KERNEL__ */
 #endif /* __AUFS_DENTRY_H__ */

fs/aufs/dinfo.c

@@ -34,6 +34,7 @@ struct au_dinfo *au_di_alloc(struct super_block *sb, unsigned int lsc)
 		dinfo->di_btop = -1;
 		dinfo->di_bbot = -1;
 		dinfo->di_bwh = -1;
+		dinfo->di_bdiropq = -1;
 		for (i = 0; i < nbr; i++)
 			dinfo->di_hdentry[i].hd_id = -1;
 		goto out;
@@ -235,6 +236,34 @@ struct dentry *au_h_dptr(struct dentry *dentry, aufs_bindex_t bindex)
 	return d;
 }
 
+aufs_bindex_t au_dbtail(struct dentry *dentry)
+{
+	aufs_bindex_t bbot, bwh;
+
+	bbot = au_dbbot(dentry);
+	if (0 <= bbot) {
+		bwh = au_dbwh(dentry);
+		if (!bwh)
+			return bwh;
+		if (0 < bwh && bwh < bbot)
+			return bwh - 1;
+	}
+	return bbot;
+}
+
+aufs_bindex_t au_dbtaildir(struct dentry *dentry)
+{
+	aufs_bindex_t bbot, bopq;
+
+	bbot = au_dbtail(dentry);
+	if (0 <= bbot) {
+		bopq = au_dbdiropq(dentry);
+		if (0 <= bopq && bopq < bbot)
+			bbot = bopq;
+	}
+	return bbot;
+}
+
 /* ---------------------------------------------------------------------- */
 
 void au_set_h_dptr(struct dentry *dentry, aufs_bindex_t bindex,