From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jamie Lokier Subject: Re: [patch v3] splice: fix race with page invalidation Date: Thu, 31 Jul 2008 01:11:31 +0100 Message-ID: <20080731001131.GA30900@shareable.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: torvalds@linux-foundation.org, jens.axboe@oracle.com, akpm@linux-foundation.org, nickpiggin@yahoo.com.au, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org To: Miklos Szeredi Return-path: Received: from mail2.shareable.org ([80.68.89.115]:56613 "EHLO mail2.shareable.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761682AbYGaALm (ORCPT ); Wed, 30 Jul 2008 20:11:42 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: > > And by papering it over, it then just makes people less likely to bother > > with the real issue. > > I think you are talking about a totally separate issue: that NFSD's > use of splice can result in strange things if the file is truncated > while being read. But this is an NFSD issue and I don't see that it > has _anything_ to do with the above bug in splice. I think you are > just confusing the two things. I'm more concerned by sendfile() users like Apache, Samba, FTPd. In an earlier thread on this topic, I asked if the splice bug can also result in sendfile() sending blocks of zeros, when a file is truncated after it has been sent, and the answer was yes probably. Not that I checked or anything. But if it affects sendfile() it's a bigger deal - that has many users. Assuming it does affect sendfile(), it's exasperated by not being able to tell when a sendfile() has finished with the pages its sending. E.g. you can't lock the file or otherwise synchronise with another program which wants to modify the file. -- Jamie