1 files changed, 35 insertions, 3 deletions

diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 5819e9b0ee22..2043af2141c1 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -161,6 +161,7 @@ struct dentry_operations {
 	struct vfsmount *(*d_automount)(struct path *);
 	int (*d_manage)(struct dentry *, bool);
 	struct inode *(*d_select_inode)(struct dentry *, unsigned);
+	struct dentry *(*d_real)(struct dentry *, struct inode *);
 	void (*d_canonical_path)(const struct path *, struct path *);
 } ____cacheline_aligned;
 
@@ -228,6 +229,7 @@ struct dentry_operations {
 #define DCACHE_MAY_FREE			0x00800000
 #define DCACHE_FALLTHRU			0x01000000 /* Fall through to lower layer */
 #define DCACHE_OP_SELECT_INODE		0x02000000 /* Unioned entry: dcache op selects inode */
+#define DCACHE_OP_REAL			0x08000000
 
 extern seqlock_t rename_lock;
 
@@ -410,9 +412,7 @@ static inline bool d_mountpoint(const struct dentry *dentry)
  */
 static inline unsigned __d_entry_type(const struct dentry *dentry)
 {
-	unsigned type = READ_ONCE(dentry->d_flags);
-	smp_rmb();
-	return type & DCACHE_ENTRY_TYPE;
+	return dentry->d_flags & DCACHE_ENTRY_TYPE;
 }
 
 static inline bool d_is_miss(const struct dentry *dentry)
@@ -585,4 +585,36 @@ static inline struct dentry *d_backing_dentry(struct dentry *upper)
 	return upper;
 }
 
+static inline struct dentry *d_real(struct dentry *dentry)
+{
+	if (unlikely(dentry->d_flags & DCACHE_OP_REAL))
+		return dentry->d_op->d_real(dentry, NULL);
+	else
+		return dentry;
+}
+
+static inline struct inode *vfs_select_inode(struct dentry *dentry,
+					     unsigned open_flags)
+{
+	struct inode *inode = d_inode(dentry);
+
+	if (inode && unlikely(dentry->d_flags & DCACHE_OP_SELECT_INODE))
+		inode = dentry->d_op->d_select_inode(dentry, open_flags);
+
+	return inode;
+}
+
+/**
+ * d_real_inode - Return the real inode
+ * @dentry: The dentry to query
+ *
+ * If dentry is on an union/overlay, then return the underlying, real inode.
+ * Otherwise return d_inode().
+ */
+static inline struct inode *d_real_inode(struct dentry *dentry)
+{
+	return d_backing_inode(d_real(dentry));
+}
+
+
 #endif	/* __LINUX_DCACHE_H */