From: Yongqiang Yang Subject: Re: Bug with "fix partial page writes" [3.2-rc regression] Date: Tue, 6 Dec 2011 11:08:36 +0800 Message-ID: References: <20111121165626.GD14568@thunk.org> <4EDD729E.2060402@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Hugh Dickins , "Ted Ts'o" , Curt Wohlgemuth , Surbhi Palande , Rafael Wysocki , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org To: Allison Henderson Return-path: Received: from mail-gx0-f174.google.com ([209.85.161.174]:40550 "EHLO mail-gx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756393Ab1LFDIh convert rfc822-to-8bit (ORCPT ); Mon, 5 Dec 2011 22:08:37 -0500 In-Reply-To: <4EDD729E.2060402@linux.vnet.ibm.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi Allison, I noticed another problem which has nothing to do with punching hole. __block_write_begin does not zero buffers beyond EOF.(I guess you tried to zero them in your code, am I right? ) When users mapread beyond EOF, users get non-zero data. I am not sure zero or non-zero data should be, but fsx thinks they should be zero data and reports an error. It I understand the problem right, it happens more often with punch hol= e. Yongqiang. On Tue, Dec 6, 2011 at 9:40 AM, Allison Henderson wrote: > On 12/05/2011 04:38 PM, Hugh Dickins wrote: >> >> On Mon, 21 Nov 2011, Hugh Dickins wrote: >>> >>> On Mon, 21 Nov 2011, Ted Ts'o wrote: >>>> >>>> On Sun, Nov 20, 2011 at 12:59:10PM -0800, Hugh Dickins wrote: >>>>> >>>>> On Tue, 8 Nov 2011, Curt Wohlgemuth wrote: >>>>> It appears that there's a bug with this patch: >> >> >> This has been outstanding for a month now, and we've heard no progre= ss: >> please revert commit 02fac1297eb3 "ext4: fix partial page writes" fo= r rc5. >> >> The problems appear on a 1k-blocksize filesystem under memory pressu= re: >> the hunk in ext4_da_write_end() causes oops, because it's playing wi= th >> a page after generic_write_end() dropped our last reference to it; a= nd >> backing out the hunk in ext4_da_write_begin() is then found to stop >> rare data corruption seen when kbuilding. >> >> Although I earlier reported that backing out the patch caused an fsx >> test to fail earlier, I've since found great variation in how soon i= t >> fails, and seen it fail just as quickly with 02fac1297eb3 still in. >> I also reported that I had to go back to 2.6.38 for fsx not to fail >> under memory pressure: you won't be surprised that that turned out t= o >> be because 2.6.38 defaults nomblk_io_submit but 2.6.39 mblk_io_submi= t. >> >> Thanks, >> Hugh >> > > > Hi there, > > Have you tried Yongqiang's patch "[PATCH 1/2] ext4: let mpage_submit_= io > works well when blocksize < pagesize" ? =A0I have tried it and it doe= s seem to > help, but I am still running into some failures that I am trying to d= ebug, > but let please let us know if it helps the issues that you are seeing= =2E =A0Thx! > > Allison Henderson > --=20 Best Wishes Yongqiang Yang -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html