Re: Oops with ext4 from 2.6.27-rc3

Eric Sandeen
2008-08-13T22:20:03Z

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