Re: [Qemu-devel] 'commit' error for 'all': No medium found

[Jan Kiszka]

On 2013-02-25 14:05, Jeff Cody wrote:
> On Sun, Feb 24, 2013 at 07:29:31PM +0100, Jan Kiszka wrote:
>> Hi,
>>
>> I'm seeing this with git head and 1.4. Apparently, commit on a
>> non-populated medium now generates this error instead of ignoring it
>> like in the past. As we stop iterating over the block devices while
>> doing "all", this may leaving uncommitted data behind.
>>
>> Didn't test, but I suspect 58513bde83 has something to do with it.
>>
>> Jan
>>
> 
> Hi Jan,
> 
> That commit just affected the reporting on the error - for the "all"
> case, bdrv_commit_all() still returned error on the first failure.
> When that happened 'commit' may have indicated success rather than
> error, depending on the error.

Sorry, I just picked on the first commit that jumped into my eyes.

> 
> That would have also left uncommitted data behind, but done so
> silently and reported success.
> 
> However, commit e8877497 added error checking to the bdrv_commit()
> return value in bdrv_commit_all() - before that bdrv_commit_all()
> ignored all error returns of bdrv_commit().
> 
> Do you think there specific error returns that we should ignore then, in
> bdrv_commit_all(), such as -ENOMEDIUM?

I think commit on a device without a medium should be a nop (as the
commit backlog is empty - provided it's correctly dropped on eject).

> 
> Also, could you expand on what you mean by non-populated
> medium (test case) - is the error being returned "No medium found"?

This is a default PC setup: the floppy tends to be not injected, thus
"commit all" now reports this error. If there is a blockdev after the
floppy in our list, it will not be committed this way. Luckly, the HD is
queued before the FD.

Jan

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