switch dentry_open() to struct path, make it grab references itself

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 34acf51..8fabb03 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2060,8 +2060,7 @@
 extern struct file *filp_open(const char *, int, umode_t);
 extern struct file *file_open_root(struct dentry *, struct vfsmount *,
 				   const char *, int);
-extern struct file * dentry_open(struct dentry *, struct vfsmount *, int,
-				 const struct cred *);
+extern struct file * dentry_open(const struct path *, int, const struct cred *);
 extern int filp_close(struct file *, fl_owner_t id);
 extern char * getname(const char __user *);
 enum {