Re: ext3: slow symlink corruption on umount...

[Arthur Jones]

Some additional info -- and attempting to cast a wider
net on the CC:

I do not see the long symlink corruption with mount -o data=writeback
and we've now seen a couple cases where the symlink corruption
does not require a umount...

Arthur

On Fri, Oct 24, 2008 at 11:37:34AM -0700, Arthur Jones wrote:
> Hi All,  I'm seeing slow symlink corruption on ext3 on linux-2.6.27,
> yesterday's linux-2.6 git tree and 2.6.9 RHEL4.7.  I.e. every kernel
> I've tried I see this effect.  To reproduce this, I need:
> 
> * 250MB + tar file in memory (tmpfs or in the buffer cache)
> * long symlinks in the tar file (over 60 characters)
> * umount immediately after untarring
> 
> What I see is that the symlinks are corrupted, e.g.:
> 
> # ls -l etc/vmware-vix-disklib
> etc/vmware-vix-disklib -> ??f
> 
> fsck shows:
> 
> Symlink /etc/vmware-vix-disklib (inode #16454) is invalid.
> 
> Debugfs shows:
> 
> debugfs:  stat <16454>
> Inode: 16454   Type: symlink    Mode:  0777   Flags: 0x0   Generation: 1431972005
> User:     0   Group:     0   Size: 65
> File ACL: 0    Directory ACL: 0
> Links: 1   Blockcount: 8
> Fragment:  Address: 0    Number: 0    Size: 0
> ctime: 0x4900ac69 -- Thu Oct 23 09:55:05 2008
> atime: 0x4900ac84 -- Thu Oct 23 09:55:32 2008
> mtime: 0x4900ac69 -- Thu Oct 23 09:55:05 2008
> BLOCKS:
> (0):56034
> TOTAL: 1
> 
> I'm still tracking down exactly what's going on.  Anyone seen
> anything like this before?  ext2 does not show this effect (I've
> not tried ext4).  It happens when the backing block device is
> a SATA drive or flash.
> 
> Thanks,
> 
> Arthur
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