Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751250AbVK3OmT (ORCPT ); Wed, 30 Nov 2005 09:42:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751252AbVK3OmS (ORCPT ); Wed, 30 Nov 2005 09:42:18 -0500 Received: from adsl-80.mirage.euroweb.hu ([193.226.228.80]:4882 "EHLO dorka.pomaz.szeredi.hu") by vger.kernel.org with ESMTP id S1751250AbVK3OmS (ORCPT ); Wed, 30 Nov 2005 09:42:18 -0500 To: dhowells@redhat.com CC: torvalds@osdl.org, akpm@osdl.org, hugh@veritas.com, aia21@cam.ac.uk, hch@infradead.org, linux-kernel@vger.kernel.org In-reply-to: <5425.1133359116@warthog.cambridge.redhat.com> (message from David Howells on Wed, 30 Nov 2005 13:58:36 +0000) Subject: Re: [PATCH] Add notification of page becoming writable to VMA ops [try #3] References: <15253.1130246296@warthog.cambridge.redhat.com> <1130168619.19518.43.camel@imp.csi.cam.ac.uk> <1130167005.19518.35.camel@imp.csi.cam.ac.uk> <7872.1130167591@warthog.cambridge.redhat.com> <9792.1130171024@warthog.cambridge.redhat.com> <5425.1133359116@warthog.cambridge.redhat.com> Message-Id: From: Miklos Szeredi Date: Wed, 30 Nov 2005 15:40:46 +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1158 Lines: 30 > The attached patch adds a new VMA operation to notify a filesystem or other > driver about the MMU generating a fault because userspace attempted to write > to a page mapped through a read-only PTE. > > This facility permits the filesystem or driver to: > > (*) Implement storage allocation/reservation on attempted write, and so to > deal with problems such as ENOSPC more gracefully (perhaps by generating > SIGBUS). > > (*) Delay making the page writable until the contents have been written to a > backing cache. This is useful for NFS/AFS when using FS-Cache/CacheFS. > It permits the filesystem to have some guarantee about the state of the > cache. (*) account and limit number of dirty pages This is one piece of the puzze needed to make shared writable mapping work safely in FUSE. > Updated to 2.6.14-git14. But doesn't apply against 2.6.15-rc3 or -rc3-mm1. 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/