Re: btrfs csum failed on git .pack file

[Jens Axboe <jens.axboe@oracle.com>]

On Thu, Sep 17 2009, Markus Trippelsdorf wrote:
> On Tue, Sep 08, 2009 at 10:00:42PM +0200, Jens Axboe wrote:
> > On Mon, Sep 07 2009, Markus Trippelsdorf wrote:
> > > Just got this error today in my dmesg:
> > > btrfs csum failed ino 1483065 off 158482432 csum 4283543305 private 43905798
> > > 
> > > linux % find . -inum 1483065
> > > ./.git/objects/pack/pack-f9251bcc6a8afe3c92193e14d1d742f2f0182ce5.pack
> > > 
> > > It's the main pack file from my git linux kernel tree:
> > > 
> > > linux % ls -l ./.git/objects/pack/
> > > total 562848
> > > -rw-r--r-- 1 markus markus   1891324 2008-11-29 19:49 pack-011b43fa6956667db5e67fba859e40cb4b154226.idx
> > > -rw-r--r-- 1 markus markus  44002938 2008-11-29 19:54 pack-011b43fa6956667db5e67fba859e40cb4b154226.pack.temp
> > > -rw-r--r-- 1 markus markus    730332 2008-11-29 19:49 pack-67be92b3fab3dab175683582dab0b719517e55a5.idx
> > > -r--r--r-- 1 markus markus  36061684 2009-09-06 21:48 pack-f9251bcc6a8afe3c92193e14d1d742f2f0182ce5.idx
> > > -r--r--r-- 1 markus markus 335202742 2009-09-06 21:48 pack-f9251bcc6a8afe3c92193e14d1d742f2f0182ce5.pack
> > > -rw------- 1 markus markus 158457856 2009-09-07 22:15 tmp_pack_OUdxER
> > > 
> > > I'm running the latest git kernel and I've been using btrfs as my root
> > > fs for the last few weeks without problems so far.
> > 
> > Hmm, I ran into something very similar. Care to check what the corrupted
> > block of data looks like (and how big it is)?
> 
> I've hit the same problem again today:
> 
> btrfs csum failed ino 1826333 off 150208512 csum 4148434891 private 1660028275
> 
> The file in question is:
> ./.git/objects/pack/pack-a2330b703d5a7fd62626b39a5fdfb6eecf739d0d.pack
> 
> I can't read the file directly, because of the csum mismatch:

Chris, is there a way to force reading the file? Seems like that would
be a very handy feature.

Markus, not sure if that works, but you could always try and remount
with data checksumming disabled.

mount /dev/fooX -o remount,rw,nodatasum

should do the trick.

-- 
Jens Axboe