From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-15?Q?Luk=E1=A8_Czerner?= Subject: Re: [PATCH 6/6] ext4/242: Add ext4 specific test for fallocate zero range Date: Tue, 25 Feb 2014 22:27:40 +0100 (CET) Message-ID: References: <1393355728-12056-1-git-send-email-lczerner@redhat.com> <1393355728-12056-6-git-send-email-lczerner@redhat.com> <20140225205349.GD13647@dastard> Mime-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="8323328-150801687-1393363663=:12444" Cc: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com To: Dave Chinner Return-path: Received: from mx1.redhat.com ([209.132.183.28]:25292 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750941AbaBYWEg (ORCPT ); Tue, 25 Feb 2014 17:04:36 -0500 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323328-150801687-1393363663=:12444 Content-Type: TEXT/PLAIN; charset=ISO-8859-15 Content-Transfer-Encoding: 8BIT On Tue, 25 Feb 2014, LukᨠCzerner wrote: > Date: Tue, 25 Feb 2014 22:01:06 +0100 (CET) > From: LukᨠCzerner > To: Dave Chinner > Cc: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com > Subject: Re: [PATCH 6/6] ext4/242: Add ext4 specific test for fallocate zero > range > > On Wed, 26 Feb 2014, Dave Chinner wrote: > > > Date: Wed, 26 Feb 2014 07:53:49 +1100 > > From: Dave Chinner > > To: Lukas Czerner > > Cc: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com > > Subject: Re: [PATCH 6/6] ext4/242: Add ext4 specific test for fallocate zero > > range > > > > On Tue, Feb 25, 2014 at 08:15:28PM +0100, Lukas Czerner wrote: > > > This is copy of xfs/242. However it's better to make it file system > > > specific because the range can be zeroes either directly by writing > > > zeroes, or converting to unwritten extent, so the actual result might > > > differ from file system to file system. > > > > You could say the same thing about preallocation using unwritten > > extents. Yet, funnily enough, we have generic tests for them because > > all filesystems currently use unwritten extents for preallocation > > and behave identically.... > > > > This test is no different - all filesystems currently use unwritten > > extents, and so this test should be generic because all existing > > filesystems *should* behave the same. > > > > When we get a filesystem that zeros rather uses unwritten extents, > > we can add a new *generic* test that tests for zeroed data extents > > rather than unwritten extents. All that we will need is a method of > > checking what behaviour the filesystem has and adding that to a > > _requires directive to ensure the correct generic fallocate tests > > are run... > > Currently xfs/242 fails on xfs for me and it does behave differently > than ext4. Also I had to change to 242.out a bit because ext4 was > a little different. It seems to me that it was expected that when > the extent is small enough it would be overwritten by zeroes rather > than converted to unwritten, but I have not looked into > implementation. > > Btw this kind of optimization is actually something I've been > thinking of as well for ext4. Rather than going though the hassle of > changing extents around it might be worth in some situation to zero > out. But that's an optimization I have not implemented yet. Oops, I am taking it back. It's just too late and apparently I've overlooked something. -Lukas > > -Lukas > > > > > > Cheers, > > > > Dave. > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > --8323328-150801687-1393363663=:12444--