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Date: Wed, 09 Feb 2011 10:12:46 +0100
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] qcow2: Fix error handling for immediate
	backing file read failure
References: <1297185328-23210-1-git-send-email-kwolf@redhat.com>
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To: Markus Armbruster <armbru@redhat.com>
Cc: qemu-devel@nongnu.org

Am 08.02.2011 18:43, schrieb Markus Armbruster:
> Kevin Wolf <kwolf@redhat.com> writes:
> 
>> Requests could return success even though they failed when bdrv_aio_readv
>> returned NULL for a backing file read.
>>
>> Reported-by: Chunqiang Tang <ctang@us.ibm.com>
>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
>> ---
>>  block/qcow2.c |    4 +++-
>>  1 files changed, 3 insertions(+), 1 deletions(-)
>>
>> diff --git a/block/qcow2.c b/block/qcow2.c
>> index 28338bf..647c2a4 100644
>> --- a/block/qcow2.c
>> +++ b/block/qcow2.c
>> @@ -479,8 +479,10 @@ static void qcow2_aio_read_cb(void *opaque, int ret)
>>                  BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
>>                  acb->hd_aiocb = bdrv_aio_readv(bs->backing_hd, acb->sector_num,
>>                                      &acb->hd_qiov, n1, qcow2_aio_read_cb, acb);
>> -                if (acb->hd_aiocb == NULL)
>> +                if (acb->hd_aiocb == NULL) {
>> +                    ret = -EIO;
>>                      goto done;
>> +                }
>>              } else {
>>                  ret = qcow2_schedule_bh(qcow2_aio_read_bh, acb);
>>                  if (ret < 0)
> 
> Good catch.
> 
> Nearby
> 
>         if (qcow2_decompress_cluster(bs, acb->cluster_offset) < 0)
>             goto done;
> 
> looks suspicious to my ignorant eyes.  Is it okay?

No, it's wrong as well, and it's the second part of Chunquiang Tang's
bug report. I started a patch for it yesterday, but didn't have time to
test it because I didn't expect my train to wait. ;-) I'll send it today.

Kevin