1 files changed, 47 insertions, 1 deletions

diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 7cb043d8f4e8..f8506e8dd4d4 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -123,7 +123,10 @@ struct dentry {
 	unsigned long d_time;		/* used by d_revalidate */
 	void *d_fsdata;			/* fs-specific data */
 
-	struct list_head d_lru;		/* LRU list */
+	union {
+		struct list_head d_lru;		/* LRU list */
+		wait_queue_head_t *d_wait;	/* in-lookup ones only */
+	};
 	struct list_head d_child;	/* child of parent list */
 	struct list_head d_subdirs;	/* our children */
 	/*
@@ -131,6 +134,7 @@ struct dentry {
 	 */
 	union {
 		struct hlist_node d_alias;	/* inode alias list */
+		struct hlist_bl_node d_in_lookup_hash;	/* only for in-lookup ones */
 	 	struct rcu_head d_rcu;
 	} d_u;
 };
@@ -161,6 +165,7 @@ 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 *);
 } ____cacheline_aligned;
 
 /*
@@ -229,6 +234,9 @@ struct dentry_operations {
 #define DCACHE_OP_SELECT_INODE		0x02000000 /* Unioned entry: dcache op selects inode */
 
 #define DCACHE_ENCRYPTED_WITH_KEY	0x04000000 /* dir is encrypted with a valid key */
+#define DCACHE_OP_REAL			0x08000000
+
+#define DCACHE_PAR_LOOKUP		0x10000000 /* being looked up (with parent locked shared) */
 
 extern seqlock_t rename_lock;
 
@@ -246,6 +254,8 @@ extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op
 /* allocate/de-allocate */
 extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
 extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
+extern struct dentry * d_alloc_parallel(struct dentry *, const struct qstr *,
+					wait_queue_head_t *);
 extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
 extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
 extern struct dentry * d_exact_alias(struct dentry *, struct inode *);
@@ -365,6 +375,22 @@ static inline void dont_mount(struct dentry *dentry)
 	spin_unlock(&dentry->d_lock);
 }
 
+extern void __d_lookup_done(struct dentry *);
+
+static inline int d_in_lookup(struct dentry *dentry)
+{
+	return dentry->d_flags & DCACHE_PAR_LOOKUP;
+}
+
+static inline void d_lookup_done(struct dentry *dentry)
+{
+	if (unlikely(d_in_lookup(dentry))) {
+		spin_lock(&dentry->d_lock);
+		__d_lookup_done(dentry);
+		spin_unlock(&dentry->d_lock);
+	}
+}
+
 extern void dput(struct dentry *);
 
 static inline bool d_managed(const struct dentry *dentry)
@@ -555,4 +581,24 @@ 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;
+}
+
+
 #endif	/* __LINUX_DCACHE_H */