linux-kernel - Re: EXT3 File System Corruption 2.6.34

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Date:	Tue, 08 Jun 2010 16:33:18 +0300
From:	Török Edwin <edwintorok@...il.com>
To:	Theodore Tso <tytso@....EDU>
CC:	Jeffrey Merkey <jeffmerkey@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: EXT3 File System Corruption 2.6.34

On 06/08/2010 02:14 PM, Theodore Tso wrote:
> 
> If you pull the plug without fsyncing the file, you will end up with a zero-length file -- or possibly no file at all, even with data=ordered.  If you really want to preserve data after pulling the power cord immediately after a write were the application hasn't done an fsync() or a sync() call, you can mount the file system with the mount option -o sync --- but then the performance will be horrible.
> 
> It's all a tradeoff of what you think is important....
> 

I think you should either get the old file, or the new file (if you
don't fsync), and not some random data from another file.
The manual entry for data=writeback only says that you may get old data
after a crash/recovery, not that you may get old/new data from *another*
file.

On the other hand I didn't specify any mount options, and I got
data=ordered. So is data=ordered the default or not?
Or does it depend whether you use ext3 or ext4 driver for ext3?

/etc/fstab has:
/dev/md3        /               ext3    noatime,errors=remount-ro 0       1

and my ext* related config options:
# CONFIG_EXT2_FS is not set
# CONFIG_EXT3_FS is not set
CONFIG_EXT4_FS=y
CONFIG_EXT4_USE_FOR_EXT23=y
CONFIG_EXT4_FS_XATTR=y
# CONFIG_EXT4_FS_POSIX_ACL is not set
# CONFIG_EXT4_FS_SECURITY is not set
# CONFIG_EXT4_DEBUG is not set
# CONFIG_DEBUG_BLOCK_EXT_DEVT is not set

So I use the ext4 driver for the ext3 partition (I intended to convert
it to ext4 at some point, but didn't have time to do so yet).

This is with 2.6.34-00179-gdebb980 (drm-radeon-testing, which is
basically 2.6.34 + some radeon specific stuff).

Best regards,
--Edwin
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