linux-ext4 - Re: Oops with ext4 from 2.6.27-rc3

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Date:	Wed, 13 Aug 2008 17:19:55 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	Theodore Tso <tytso@....edu>
CC:	Christian Hesse <mail@...rm.de>, linux-ext4@...r.kernel.org
Subject: Re: Oops with ext4 from 2.6.27-rc3

Theodore Tso wrote:
> On Wed, Aug 13, 2008 at 11:07:06PM +0200, Christian Hesse wrote:
>> Please look at the bottom of my last two mails... That was with your patch 
>> applied.
> 
> Sorry, I missed it.  The new BUG seems to be a bug in the delayed
> allocation code, specifically here, in fs/ext4/inode.c:ext4_da_release_space():
> 
> 	   /* figure out how many metablocks to release */
> 	   BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
> 	   mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb;
> 
> I've quickly looked at the code, and how i_reserved_meta_blocks gets
> updated, and nothing *obviously* wrong is jumping out at me.  Anyone
> else have time to investigate this a bit more deeply?

I don't :), but I tried a quick reproducer anyway and couldn't hit it ...

mkfs.ext3, mount, create non-extents file
umount, tune2fs to ext4
mount as ext4, write to file, open file O_TRUNC

... didn't oops for me :(

-Eric
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