Re: [Qemu-devel] [PATCH] qcow2: Fix refcount block allocation during qcow2_allocate_cluster_at()

[Kevin Wolf]

Am 23.04.2012 20:30, schrieb Marcelo Tosatti:
> On Mon, Apr 23, 2012 at 02:33:49PM +0200, Kevin Wolf wrote:
>> Am 23.04.2012 01:35, schrieb Marcelo Tosatti:
>>> On Sun, Apr 22, 2012 at 08:18:49PM -0300, Marcelo Tosatti wrote:
>>>> On Fri, Apr 20, 2012 at 03:56:01PM +0200, Kevin Wolf wrote:
>>>>> Refcount block allocation and refcount table growth rely on
>>>>> s->free_cluster_index pointing to somewhere after the current
>>>>> allocation. Change qcow2_allocate_cluster_at() to fulfill this
>>>>> assumption.
>>>>>
>>>>> Without this change it could happen that a newly allocated refcount
>>>>> block and the allocated data block point to the same area in the image
>>>>> file, causing data corruption in the long run.
>>>>>
>>>>> This fixes a bug that became first visible after commit 250196f1.
>>>>>
>>>>> Signed-off-by: Kevin Wolf <address@hidden>
>>>>
>>>> Kevin,
>>>>
>>>> This patch fixes explicit filesystem errors (qemu-img check also OK), 
>>>> but autotest is still failing, see attached screenshot. It is not
>>>> reproducible without
>>>>
>>>> f081987ad20a8c8dc391deded55161ea8d38be5f
>>>
>>> Sorry, i meant
>>>
>>> commit 250196f19c6e7df12965d74a5073e10aba06c802
>>> Author: Kevin Wolf <address@hidden>
>>> Date:   Fri Mar 2 14:10:54 2012 +0100
>>>
>>>     qcow2: Reduce number of I/O requests
>>
>> The screenshot doesn't really give a lot of information, but let's
>> assume that _something_ must have been corrupted... Can you try finding
>> the corrupted file (e.g. using rpm -V) and see in which way it differs
>> from the real one?
>>
>> Kevin
> 
> Unfortunately no, /boot/vmlinuz is gone on the last install
> (screenshot).
> 
> It should be easy to reproduce, install Fedora.8.64, or i
> can upload an image later tonight if that is helpful.

Nope, can't reproduce. Fedora 8 installs and boots just fine (8 GB disk,
default qcow2 cluster size, just clicked through the installer with
default options).

Kevin