From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shaya Potter Subject: using page cache directly? Date: Fri, 21 Nov 2003 15:04:37 -0500 Sender: linux-fsdevel-owner@vger.kernel.org Message-ID: <3FBE6FD5.6080502@cs.columbia.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from ober.cs.columbia.edu ([128.59.18.100]:65010 "EHLO ober.cs.columbia.edu") by vger.kernel.org with ESMTP id S264428AbTKUUEf (ORCPT ); Fri, 21 Nov 2003 15:04:35 -0500 Received: from cs.columbia.edu (user-0ccem6d.cable.mindspring.com [24.199.88.205]) (authenticated bits=0) by ober.cs.columbia.edu (8.12.10/8.12.10) with ESMTP id hALK4XUP023626 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Fri, 21 Nov 2003 15:04:34 -0500 (EST) To: linux-fsdevel@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org I'm trying to write a stackable file system that supports branching (i.e. mount time options of old_branch and new_branch). In order to do it, I need to version the directories as well, what I'd like to do is have a file act as the directory (basically ";branch" on the underlying fs inside the right dir) which will just map "Stacked Filename" to "underlying filename". If I were doing it in user space, I'd just mmap the file, and deal with it directly like that, but as I understand it's not really appropriate to do that inside the kernel (and only possible w/ vmalloc'd pages). The correct way (I was told) is to use the page cache. As don't have a lot of experience with that, can someone point me in the right direction so I can learn to deal w/ it. thanks, shaya