From: Eric Sandeen Subject: Re: Files full of zeros with coreutils-8.11 and xfs (FIEMAP related?) Date: Thu, 14 Apr 2011 10:56:16 -0500 Message-ID: <4DA71920.9@sandeen.net> References: <20110414102608.GA1678@x4.trippels.de> <20110414120635.GB1678@x4.trippels.de> <20110414140222.GB1679@x4.trippels.de> <4DA70BD3.1070409@draigBrady.com> <4DA717B2.3020305@sandeen.net> <4DA7182B.8050409@draigBrady.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: xfs-oss , linux-ext4@vger.kernel.org, coreutils@gnu.org, Markus Trippelsdorf To: =?ISO-8859-1?Q?P=E1draig_Brady?= Return-path: Received: from sandeen.net ([63.231.237.45]:43317 "EHLO mail.sandeen.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758734Ab1DNP4S (ORCPT ); Thu, 14 Apr 2011 11:56:18 -0400 In-Reply-To: <4DA7182B.8050409@draigBrady.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 4/14/11 10:52 AM, P=E1draig Brady wrote: > On 14/04/11 16:50, Eric Sandeen wrote: >> On 4/14/11 9:59 AM, P=E1draig Brady wrote: >>> On 14/04/11 15:02, Markus Trippelsdorf wrote: >>>>>> Hi P=E1draig, >>>>>> >>>>>> here you go: >>>>>> + filefrag -v unwritten.withdata = = =20 >>>>>> Filesystem type is: ef53 = = =20 >>>>>> File size of unwritten.withdata is 5120 (2 blocks, blocksize 409= 6) = =20 >>>>>> ext logical physical expected length flags = = =20 >>>>>> 0 0 274432 2560 unwritten,eof = = =20 >>>>>> unwritten.withdata: 1 extent found >>>>>> >>>>>> Please notice that this also happens with ext4 on the same kerne= l.=20 >>>>>> Btrfs is fine. >>>>> >>>> `filefrag -vs` fixes the issue on both xfs and ext4. >>> >>> So in summary, currently on (2.6.39-rc3), the following >>> will (usually?) report a single unwritten extent, >>> on both ext4 and xfs >>> >>> fallocate -l 10MiB -n k >>> dd count=3D10 if=3D/dev/urandom conv=3Dnotrunc iflag=3Dfullblock = of=3Dk >>> filefrag -v k # grep for an extent without unwritten || fail >> >> right, that's what I see too in testing. >> >> But would the coreutils install have done a preallocation of the des= tination file? >> >> Otherwise this looks like a different bug... >> >>> This particular issue has been discussed so far at: >>> http://debbugs.gnu.org/cgi/bugreport.cgi?bug=3D8411 >>> Note there it was stated there that ext4 had this >>> fixed as of 2.6.39-rc1, so maybe there is something lurking? >> >> ext4 got a fix, but not xfs, I guess. My poor brain can't remember,= I think I started looking into it, but it's clearly still broken. >> >> Still, I don't know for sure what happened to Markus - did something= preallocate, in his case? >=20 > Well that preallocate test is failing for him > when the source file is either on ext4 or xfs. > He noticed the issue initially on XFS when copying > none preallocated files, so XFS probably just has > the general issue of needing a sync before fiemap, > where as EXT4 just has this preallocate one > (though I've not seen it myself). >=20 > cheers, > P=E1draig. >=20 well, if I simply take the preallocation step out of the testcase, it w= orks fine on xfs without a sync. So I still don't know what Markus hit... -Eric -- 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