From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754692AbYDRLxL (ORCPT ); Fri, 18 Apr 2008 07:53:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751859AbYDRLw6 (ORCPT ); Fri, 18 Apr 2008 07:52:58 -0400 Received: from mail2.shareable.org ([80.68.89.115]:46420 "EHLO mail2.shareable.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751822AbYDRLw5 (ORCPT ); Fri, 18 Apr 2008 07:52:57 -0400 Date: Fri, 18 Apr 2008 12:52:38 +0100 From: Jamie Lokier To: Szabolcs Szakacsits Cc: Bob Copeland , Miklos Szeredi , hch@infradead.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 0/7] OMFS filesystem version 3 Message-ID: <20080418115237.GA25089@shareable.org> Mail-Followup-To: Szabolcs Szakacsits , Bob Copeland , Miklos Szeredi , hch@infradead.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <1208041121-26787-1-git-send-email-me@bobcopeland.com> <20080412170304.54f139e2.akpm@linux-foundation.org> <20080413033344.GA27494@hash.localnet> <20080412205544.5e12a7d4.akpm@linux-foundation.org> <20080413080130.GA9622@infradead.org> <20080413012001.8d7967f4.akpm@linux-foundation.org> <20080413082815.GA20108@infradead.org> <20080414004521.GA30489@hash.localnet> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Szabolcs Szakacsits wrote: > If you have the free hot caches then it performs the same as in-kernel > file systems, user space isn't involved at all. Presumably if "user space isn't involved at all", it must require that user space has granted caching rights to the kernel over a FUSE cache coherency protocol? Otherwise I don't see how the kernel could coherently cache file pages for some kinds of FUSE filesystems. (E.g. sshfs, for example: every operation must surely invoke a user space request or involve granting a caching right to the kernel, to keep accesses coherent with other users of the same remote files). Ergo, either its not coherent, or there is some coherency protocol, which does require _some_ work in the user space implementation. -- Jamie