From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 8 Jun 2001 07:48:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 8 Jun 2001 07:48:22 -0400 Received: from penguin.eunet.cz ([193.86.255.66]:36616 "HELO charybda.fi.muni.cz") by vger.kernel.org with SMTP id ; Fri, 8 Jun 2001 07:48:14 -0400 From: Jan Kasprzak Date: Fri, 8 Jun 2001 13:48:02 +0200 To: linux-kernel@vger.kernel.org, xgajda@fi.muni.cz, kron@fi.muni.cz Subject: Re: CacheFS Message-ID: <20010608134802.H1100@informatics.muni.cz> In-Reply-To: <20010607133750.I1193@informatics.muni.cz> <20010607114419.A23962@cs.cmu.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <20010607114419.A23962@cs.cmu.edu>; from jaharkes@cs.cmu.edu on Thu, Jun 07, 2001 at 11:44:19AM -0400 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Jan Harkes wrote: : > Every file on the front filesystem (NFS or so) volume will be cached : > in two local files by cachefsd: The first one would contain the (parts of) : > real file content, and the second one would contain file's metadata and the : > bitmap of valid blocks (or pages) of the first file. All files in cachefsd's : > backing store would be in a per-volume directory, and will be numbered by the : > inode number from the front filesystem. : : - Intermezzo uses 'holes' in files to indicate that content isn't : available. Well, but can you see the hole from the user-space daemon? : - You might want to have a more hierarchical backing store, directory : operations in large directories are not very efficient. Yes, of course. But this is an implementation detail of cachefsd. : - I believe you are switching the meaning of front and backend : filesystems around a lot in your description. Who exactly assigns the : inode numbers? Well, let's speak about NFS, locally cached on ext2. The present implemetation takes inode number from NFS, and creates and ext2 file named - for example - /cache/%d (for file contents) and /cache/%d.attr for stat(2) data and valid blocks bitmap. The %d is an inode number from the NFS volume. : Some references, : : UserFS, PodFuk, AVFS, Thanks, -Yenya -- \ Jan "Yenya" Kasprzak http://www.fi.muni.cz/~kas/ \\ PGP: finger kas at aisa.fi.muni.cz 0D99A7FB206605D7 8B35FCDE05B18A5E // \\\ Czech Linux Homepage: http://www.linux.cz/ /// It is a very bad idea to feed negative numbers to memcpy. --Alan Cox