Re: [RFC v3 2/5] qemu-io: add zoned block device operations.

[Sam Li]

Stefan Hajnoczi <stefanha@redhat.com> 于2022年6月28日周二 16:20写道：
>
> On Mon, Jun 27, 2022 at 08:19:14AM +0800, Sam Li wrote:
> > diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
> > index 2f0d8ac25a..3f2592b9f5 100644
> > --- a/qemu-io-cmds.c
> > +++ b/qemu-io-cmds.c
> > @@ -1706,6 +1706,122 @@ static const cmdinfo_t flush_cmd = {
> >      .oneline    = "flush all in-core file state to disk",
> >  };
> >
> > +static int zone_report_f(BlockBackend *blk, int argc, char **argv)
> > +{
> > +    int ret;
> > +    int64_t offset, len, nr_zones;
> > +    int i = 0;
> > +
> > +    ++optind;
> > +    offset = cvtnum(argv[optind]);
> > +    ++optind;
> > +    len = cvtnum(argv[optind]);
> > +    ++optind;
> > +    nr_zones = cvtnum(argv[optind]);
> > +
> > +    g_autofree BlockZoneDescriptor *zones = g_new(BlockZoneDescriptor, 
> > nr_zones);
> > +    ret = blk_zone_report(blk, offset, len, &nr_zones, zones);
> > +    while (i < nr_zones) {
>
> Does blk_zone_report() set nr_zones to 0 on failure or do we need to
> check if (ret < 0) here?

I'll check if (ret<0) in zone_report and other commands in this patch as well.

>
> > +        fprintf(stdout, "start: 0x%lx, len 0x%lx, cap 0x%lx, wptr 0x%lx, "
>
> The rest of the source file uses printf() instead of fprintf(stdout,
> ...). That's usually preferred because it's shorter.
>
> > +                        "zcond:%u, [type: %u]\n",
>
> Please use PRIx64 instead of lx format specifiers for portability. On
> 32-bit hosts lx is 32-bit, not 64-bit. You can grep QEMU's code for
> examples of PRIx64.

Noted. It is necessary.

>
> > +                zones[i].start, zones[i].length, zones[i].cap, zones[i].wp,
> > +                zones[i].cond, zones[i].type);
> > +        ++i;
> > +    }
>
> A for loop is more idiomatic:
>
>   for (int i = 0; i < nr_zones; i++) {
>       ...
>   }
>
> > +    return ret;
> > +}
> > +
> > +static const cmdinfo_t zone_report_cmd = {
> > +        .name = "zone_report",
> > +        .altname = "f",
> > +        .cfunc = zone_report_f,
> > +        .argmin = 3,
> > +        .argmax = 3,
> > +        .args = "offset [offset..] len [len..] number [num..]",
>
> The arguments are "offset len number". This command does not accept
> optional offset/len/num arguments.
>
> > +        .oneline = "report a number of zones",
>
> Maybe "report zone information".
>
> > +};
> > +
> > +static int zone_open_f(BlockBackend *blk, int argc, char **argv)
> > +{
> > +    int64_t offset, len;
> > +    ++optind;
> > +    offset = cvtnum(argv[optind]);
> > +    ++optind;
> > +    len = cvtnum(argv[optind]);
> > +    return blk_zone_mgmt(blk, zone_open, offset, len);
>
> Where is the error reported? When I look at read_f() I see:
>
>     if (ret < 0) {
>         printf("read failed: %s\n", strerror(-ret));
>
> I think something similar is needed because qemu-io.c does not print an
> error message for us. The same is true for the other commands defined in
> this patch.
>
> > +}
> > +
> > +static const cmdinfo_t zone_open_cmd = {
> > +        .name = "zone_open",
> > +        .altname = "f",
> > +        .cfunc = zone_open_f,
> > +        .argmin = 2,
> > +        .argmax = 2,
> > +        .args = "offset [offset..] len [len..]",
>
> There are no optional offset/len args. The same is true for the other
> commands below.

Thanks for reviewing!

Sam