From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sun, 4 Feb 2007 04:55:49 +0100 From: Nick Piggin Subject: Re: [patch 1/9] fs: libfs buffered write leak fix Message-ID: <20070204035549.GA3502@wotan.suse.de> References: <20070129081905.23584.97878.sendpatchset@linux.site> <20070129081914.23584.23886.sendpatchset@linux.site> <20070202155236.dae54aa2.akpm@linux-foundation.org> <20070203013316.GB27300@wotan.suse.de> <20070203174947.GA2656@lazybastard.org> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20070203174947.GA2656@lazybastard.org> Sender: owner-linux-mm@kvack.org Return-Path: To: =?iso-8859-1?Q?J=F6rn?= Engel Cc: Andrew Morton , Linux Kernel , Linux Filesystems , Linux Memory Management List-ID: On Sat, Feb 03, 2007 at 05:49:47PM +0000, Jorn Engel wrote: > On Sat, 3 February 2007 02:33:16 +0100, Nick Piggin wrote: > > > > If doing a partial-write, simply clear the whole page and set it uptodate > > (don't need to get too tricky). > > That sounds just like a bug I recently fixed in logfs. prepare_write() > would clear the page, commit_write() would write the whole page. Bug > can be reproduced with a simple testcate: > > echo -n foo > foo > echo -n bar >> foo > cat foo > > With the bug, the second write will replace "foo" with "\0\0\0" and > cat will return "bar". Doing a read instead of clearing the page will > return "foobar", as would be expected. > > Can you hit the same bug with your patch or did I miss something? Yes, the page is only cleared if it is not uptodate. This is fine for the simple filesystems. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org