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

[Stefan Hajnoczi]

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?

> +        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.

> +                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.

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