vfs: new d_init method

Allow filesystem to initialize dentry at allocation time.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 70a056f..15c3fa7 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -923,6 +923,7 @@
 	int (*d_compare)(const struct dentry *, const struct dentry *,
 			unsigned int, const char *, const struct qstr *);
 	int (*d_delete)(const struct dentry *);
+	int (*d_init)(struct dentry *);
 	void (*d_release)(struct dentry *);
 	void (*d_iput)(struct dentry *, struct inode *);
 	char *(*d_dname)(struct dentry *, char *, int);
@@ -995,6 +996,8 @@
 	always cache a reachable dentry. d_delete must be constant and
 	idempotent.
 
+  d_init: called when a dentry is allocated
+
   d_release: called when a dentry is really deallocated
 
   d_iput: called when a dentry loses its inode (just prior to its