From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Lutomirski <luto-3s7WtUTddSA@public.gmane.org>
Subject: Re: [Bug #14472] EXT4 corruption
Date: Tue, 3 Nov 2009 18:43:11 -0500
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To: Theodore Tso <tytso-3s7WtUTddSA@public.gmane.org>, Andrew Lutomirski <luto-3s7WtUTddSA@public.gmane.org>, "Rafael J. Wysocki" <rjw-KKrjLPT3xs0@public.gmane.org>, Linux Kernel Mailing List <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Kernel Testers List <kerne>

On Thu, Oct 29, 2009 at 5:23 PM, Theodore Tso <tytso-3s7WtUTddSA@public.gmane.org> wrote:
> On Thu, Oct 29, 2009 at 03:57:32PM -0400, Andrew Lutomirski wrote:
>>
>> This but is *not* fixed. =A0I just triggered it a few minutes ago by
>> abusing i915 and drm, which caused a panic. =A0This is slightly newe=
r
>> than 2.6.32-rc5, with a couple of i915 bugfixes thrown in.
>
> Andrew, can you test to see if this patch helps?
>
> Thanks,
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=
 =A0 =A0 =A0 =A0 =A0 =A0- Ted
>
> commit a8836b1d6f92273e001012c7705ae8f4c3d5fb65
> Author: Aneesh Kumar K.V <aneesh.kumar-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
> Date: =A0 Tue Oct 27 15:36:38 2009 +0530
>
> =A0 =A0ext4: discard preallocation during truncate
>
> =A0 =A0We need to make sure when we drop and reacquire the inode's
> =A0 =A0i_data_sem we discard the inode preallocation. Otherwise we
> =A0 =A0could have blocks marked as free in bitmap but still belonging
> =A0 =A0to prealloc space.
>
> =A0 =A0Signed-off-by: Aneesh Kumar K.V <aneesh.kumar-23VcF4HTsmIX0ybBhKVfKQ@public.gmane.org=
om>
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 5c5bc5d..a1ef1c3 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -209,6 +209,12 @@ static int try_to_extend_transaction(handle_t *h=
andle, struct inode *inode)
> =A0 =A0 =A0 =A0up_write(&EXT4_I(inode)->i_data_sem);
> =A0 =A0 =A0 =A0ret =3D ext4_journal_restart(handle, blocks_for_trunca=
te(inode));
> =A0 =A0 =A0 =A0down_write(&EXT4_I(inode)->i_data_sem);
> + =A0 =A0 =A0 /*
> + =A0 =A0 =A0 =A0* We have dropped i_data_sem. So somebody else could=
 have done
> + =A0 =A0 =A0 =A0* block allocation. So discard the prealloc space cr=
eated as a
> + =A0 =A0 =A0 =A0* part of block allocation
> + =A0 =A0 =A0 =A0*/
> + =A0 =A0 =A0 ext4_discard_preallocations(inode);
>
> =A0 =A0 =A0 =A0return ret;
> =A0}
>


It looks like 2.6.32-rc6 is supposed to fix this bug, but it also
looks like this patch didn't make it in.  Should I still be using this
patch?

Thanks,
Andy