Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753833Ab0BKNIZ (ORCPT ); Thu, 11 Feb 2010 08:08:25 -0500 Received: from fxip-0047f.externet.hu ([88.209.222.127]:51846 "EHLO pomaz-ex.szeredi.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752252Ab0BKNIY (ORCPT ); Thu, 11 Feb 2010 08:08:24 -0500 To: Tejun Heo CC: miklos@szeredi.hu, mszeredi@suse.cz, linux-kernel@vger.kernel.org, fuse-devel@lists.sourceforge.net, polynomial-c@gentoo.org, akpm@linux-foundation.org In-reply-to: <4B7400A7.5070105@kernel.org> (message from Tejun Heo on Thu, 11 Feb 2010 22:05:43 +0900) Subject: Re: [fuse-devel] [PATCH] FUSE/CUSE: implement direct mmap support References: <4B70FBE4.7050700@kernel.org> <4B7296DF.207@kernel.org> <4B729F07.8020704@kernel.org> <4B72A802.6040009@kernel.org> <4B7344A4.1030607@kernel.org> <4B73F006.7090706@kernel.org> <4B73FCF2.3020108@kernel.org> <4B7400A7.5070105@kernel.org> Message-Id: From: Miklos Szeredi Date: Thu, 11 Feb 2010 14:08:13 +0100 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1480 Lines: 34 On Thu, 11 Feb 2010, Tejun Heo wrote: > Hello, > > On 02/11/2010 09:46 PM, Miklos Szeredi wrote: > > The problem with that is you simply can't determine in advance where > > the region will grow. Okay, you can leave space according to the size > > of the file, but the size of the file can grow too. > > > > *This* is the complexity that I want to get rid of. > > Alright, then let's talk about that, not SHMLBA which doesn't really > have much to do with this. So, you're basically saying that you want > multiple address spaces. In that case, the only logical abstraction > for that are files. ie. We need to be passing file descriptors to the > server and asking the server which descriptor it would want to use, > which was the previous implementation, which you objected mentioning > that this type of direct mmap would probably be useful only for device > mmap implementations. No, I don't want to pass file descriptors (early fuse did use that for readdir and it was a mistake). Global address space for server side maps are OK. What I mind is that in the *absence* of server side maps the filesystem still has to deal with the global address space (with all its quirks). This is totally unnecessary. Thanks, Miklos -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/