Re: [PATCH v3 2/2] qcow2: Skip copy-on-write when allocating a zero cluster

[Vladimir Sementsov-Ogievskiy]

11.09.2020 13:04, Alberto Garcia wrote:
> On Fri 11 Sep 2020 11:34:37 AM CEST, Vladimir Sementsov-Ogievskiy wrote:
> > > -        if (!is_zero_cow(bs, m)) {
> > > +        ret = is_zero_cow(bs, m);
> > > +        if (ret < 0) {
> > > +            return ret;
> >
> > It's a common practice to treat block-status errors as "unknown"
> > status and not error-out immediately:
> >
> >    - really, it's not critical, we can continue assuming non-zero
> >    - if there are real problems with IO, we'll most probably fail on
> >    real read or write operation, and report its status, which seems
> >    better for user than block-status error
>
> But what's the problem exactly, does this complicate the code too much?
> :-?

Of course not :) Hmm. OK, I don't know, I'm just used to this practice in block 
jobs. Patch is correct as is:
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

> > So, I'd keep existing logic in handle_alloc_space(). And, if you agree
> > and resend, probably good to split this patch into two, one for
> > block.h/io.c and one for qcow2.c (still, I'm OK with it as one patch).
>
> Sure, I can split the patch if I have to resend it.
>
> Berto


--
Best regards,
Vladimir