Re: [PATCH] bio: decrease bi_iter.bi_size by len in the fail path

[Dongsu Park <dongsu.park@profitbricks.com>]

Hi Ming,

On 29.05.2014 00:59, Ming Lei wrote:
> On Wed, May 28, 2014 at 11:42 PM, Ming Lei <tom.leiming@gmail.com> wrote:
> > Would you mind explaining why bi_iter.bi_size need to be
> > decreased by 'len'? In the failure path, it wasn't added by
> > 'len', was it?
> 
> Actually, the correct thing may be like what did in the
> attached patch, as Maurizio discussed with me[1].

Yes, I agree. Your patch is the correct fix.
Please ignore my patch, and take yours,
<https://lkml.org/lkml/2014/5/29/370>

> Very interestingly, I have reproduced the problem one time
> with ext4/271 ext4/301 ext4/305, but won't with the attached
> patch after running it for 3 rounds.

I also had a trouble with reproducing this bug on my home desktop,
while I can reliably reproduce the bug on my office workstation.
I'm not quite sure what makes the difference.
(The same kernel, the same qemu version, the same xfstests version, etc.)

Anyway, coming back to my office, now I can confirm that your patch
fixes the bug. You can add:

Tested-by: Dongsu Park <dongsu.park@profitbricks.com>

Thanks,
Dongsu

> [tom@localhost xfstests]$ sudo ./check ext4/271 ext4/301 ext4/305
> FSTYP         -- ext4
> PLATFORM      -- Linux/x86_64 localhost 3.15.0-rc7-next-20140527+
> MKFS_OPTIONS  -- /dev/vdc
> MOUNT_OPTIONS -- -o acl,user_xattr /dev/vdc /mnt/scratch
> 
> ext4/271 1s ... 1s
> ext4/301 31s ... 32s
> ext4/305 181s ... 180s
> Ran: ext4/271 ext4/301 ext4/305
> Passed all 3 tests
> 
> Jet, could you test the attached patch?
> 
> [1], https://lkml.org/lkml/2014/5/27/327
> 
> 
> Thanks,
> -- 
> Ming Lei