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Re: data corruption after unclean shutdown, sync does not work.

To: Steve Lord <lord@xxxxxxx>
Subject: Re: data corruption after unclean shutdown, sync does not work.
From: utz lehmann <xfs@xxxxxxxxxx>
Date: Sun, 11 Feb 2001 19:17:47 +0100
Cc: utz lehmann <xfs@xxxxxxxxxx>, linux-xfs@xxxxxxxxxxx
In-reply-to: <200102111655.f1BGtm019460@xxxxxxxxxxxxxxxxxxxx>
References: <xfs@xxxxxxxxxx> <200102111655.f1BGtm019460@xxxxxxxxxxxxxxxxxxxx>
Sender: owner-linux-xfs@xxxxxxxxxxx
User-agent: Mutt/1.2.5i
hi

same problem with the change .-(


utz

Steve Lord [lord@xxxxxxx] wrote:
> 
> 
> We have been making changes in how delayed allocation data is flushed out
> to disk, we know it is not totally correct at the moment, looks like this
> is more true than I realized.
> 
> As an experiment try this change, in linvfs_write_super() in 
> fs/xfs/linux/xfs_super.c change
> 
> VFS_SYNC(vfsp, SYNC_FSDATA|SYNC_BDFLUSH|SYNC_NOWAIT|SYNC_ATTR,
> 
> to
> 
> VFS_SYNC(vfsp, SYNC_FSDATA|SYNC_BDFLUSH|SYNC_WAIT|SYNC_ATTR,
> 
> This may fix your problem, but may change the characteristics of the system
> in undesirable ways since write_super is getting called every few seconds and
> this will make it more synchronous.
> 
> If this does not help then the sync activity is not finding everything and
> things are seriously broken.
> 
> Steve
> 
> 
> > hi
> > 
> > i found a bug with the newer development kernels.
> > 
> > i have files with data corruption after hitting the reset button.
> > it seems that "sync" does not sync the data to disk.
> > 
> > i made following test:
> > 
> > 
> > cp -av /usr/src/linux/drivers/ drivers
> > diff -r -u /usr/src/linux/drivers/ drivers/  (no differs)
> > sync
> > sync
> > sync
> > 
> > hit the reset button.
> > 
> > after that, the diff reports about 190 (of 3134) files are different.
> > 
> > the files have the right size, but they are only filled with null chars.
> > xfs_bmap reports, that they have no extends.
> > 
> > i have made the test with some older kernels:
> > 
> > the last working kernel is from feb, 4th 14:00 CET.
> > the first buggy kernel is from feb, 6th 0:50 CET.
> > 
> > the tests were made on a xfs root partition (ide drive, no kio).
> > 
> > and i notice that on the buggy kernels, when the (root) fs is marked
> > readonly while shutdown, there were more diskactivity than on the good ones.
> > the data is only written to disk while marking readonly?
> > 
> > 
> > hope that helps.
> > 
> > 
> > utz
> 

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