new primitive: vfs_mkobj()

Similar to vfs_create(), but with caller-supplied callback (and
argument for it) to be used instead of ->create().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

include/linux/fs.h

@@ -1608,6 +1608,10 @@ extern int vfs_whiteout(struct inode *, struct dentry *);
 extern struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode,
 				  int open_flag);
 
+int vfs_mkobj(struct dentry *, umode_t,
+		int (*f)(struct dentry *, umode_t, void *),
+		void *);
+
 /*
  * VFS file helper functions.
  */