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Date: Thu, 14 Apr 2011 18:03:43 +0200 From: Markus Trippelsdorf <markus@...ppelsdorf.de> To: Eric Sandeen <sandeen@...deen.net> Cc: Pádraig Brady <P@...igBrady.com>, xfs-oss <xfs@....sgi.com>, linux-ext4@...r.kernel.org, coreutils@....org Subject: Re: Files full of zeros with coreutils-8.11 and xfs (FIEMAP related?) On 2011.04.14 at 10:56 -0500, Eric Sandeen wrote: > On 4/14/11 10:52 AM, Pádraig Brady wrote: > > On 14/04/11 16:50, Eric Sandeen wrote: > >> On 4/14/11 9:59 AM, Pádraig Brady wrote: > >>> On 14/04/11 15:02, Markus Trippelsdorf wrote: > >>>>>> Hi Pádraig, > >>>>>> > >>>>>> here you go: > >>>>>> + filefrag -v unwritten.withdata > >>>>>> Filesystem type is: ef53 > >>>>>> File size of unwritten.withdata is 5120 (2 blocks, blocksize 4096) > >>>>>> ext logical physical expected length flags > >>>>>> 0 0 274432 2560 unwritten,eof > >>>>>> unwritten.withdata: 1 extent found > >>>>>> > >>>>>> Please notice that this also happens with ext4 on the same kernel. > >>>>>> 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=10 if=/dev/urandom conv=notrunc iflag=fullblock of=k > >>> 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 destination 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=8411 > >>> 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? > > > > 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). > > > > cheers, > > Pádraig. > > > > well, if I simply take the preallocation step out of the testcase, it works fine on xfs without a sync. > > So I still don't know what Markus hit... Maybe it's delalloc: x4 /tmp # dd count=10 if=/dev/urandom conv=notrunc iflag=fullblock of=k 10+0 records in 10+0 records out 5120 bytes (5.1 kB) copied, 0.0021822 s, 2.3 MB/s x4 /tmp # filefrag -v k Filesystem type is: 58465342 File size of k is 5120 (2 blocks, blocksize 4096) ext logical physical expected length flags 0 0 0 16 unknown,delalloc,eof k: 1 extent found x4 /tmp # sync x4 /tmp # filefrag -v k Filesystem type is: 58465342 File size of k is 5120 (2 blocks, blocksize 4096) ext logical physical expected length flags 0 0 26960045 16 eof k: 1 extent found -- Markus -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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