Re: [RFC v4 2/9] qemu-io: add zoned block device operations.

[Stefan Hajnoczi]

On Mon, 11 Jul 2022 at 22:17, Sam Li <faithilikerun@gmail.com> wrote:
> +int bdrv_co_zone_report(BlockDriverState *bs, int64_t offset,
> +                        int64_t *nr_zones,
> +                        BlockZoneDescriptor *zones)
> +{
> +    BlockDriver *drv = bs->drv;
> +    CoroutineIOCompletion co = {
> +            .coroutine = qemu_coroutine_self(),
> +    };
> +    IO_CODE();
> +
> +    bdrv_inc_in_flight(bs);
> +    if (!drv || (!drv->bdrv_co_zone_report)) {
> +        co.ret = -ENOTSUP;
> +        goto out;
> +    }
> +
> +    if (drv->bdrv_co_zone_report) {

At this point we know drv->bdrv_co_zone_report is non-NULL because it
has been checked already. The if statement can be dropped.

> +        co.ret = drv->bdrv_co_zone_report(bs, offset, nr_zones, zones);
> +    } else {
> +        co.ret = -ENOTSUP;

This case is already handled by if (... ||
(!drv->bdrv_co_zone_report)) above. The else body can be dropped.

> +        goto out;
> +        qemu_coroutine_yield();
> +    }
> +
> +out:
> +    bdrv_dec_in_flight(bs);
> +    return co.ret;
> +}
> +
> +int bdrv_co_zone_mgmt(BlockDriverState *bs, enum zone_op op,

Please follow QEMU coding style and typedef BdrvZoneOp instead of
writing out enum zone_op.

> +        int64_t offset, int64_t len)
> +{
> +    BlockDriver *drv = bs->drv;
> +    CoroutineIOCompletion co = {
> +            .coroutine = qemu_coroutine_self(),
> +    };
> +    IO_CODE();
> +
> +    bdrv_inc_in_flight(bs);
> +    if (!drv || (!drv->bdrv_co_zone_mgmt)) {
> +        co.ret = -ENOTSUP;
> +        goto out;
> +    }
> +
> +    if (drv->bdrv_co_zone_mgmt) {
> +        co.ret = drv->bdrv_co_zone_mgmt(bs, op, offset, len);
> +    } else {
> +        co.ret = -ENOTSUP;
> +        goto out;
> +        qemu_coroutine_yield();
> +    }

Same comments here.

> +
> +out:
> +    bdrv_dec_in_flight(bs);
> +    return co.ret;
> +}
> +
>  void *qemu_blockalign(BlockDriverState *bs, size_t size)
>  {
>      IO_CODE();
> diff --git a/include/block/block-io.h b/include/block/block-io.h
> index 053a27141a..a0ae140452 100644
> --- a/include/block/block-io.h
> +++ b/include/block/block-io.h
> @@ -80,6 +80,13 @@ int bdrv_co_ioctl(BlockDriverState *bs, int req, void 
> *buf);
>  /* Ensure contents are flushed to disk.  */
>  int coroutine_fn bdrv_co_flush(BlockDriverState *bs);
>
> +/* Report zone information of zone block device. */
> +int coroutine_fn bdrv_co_zone_report(BlockDriverState *bs, int64_t offset,
> +                                     int64_t *nr_zones,
> +                                     BlockZoneDescriptor *zones);
> +int coroutine_fn bdrv_co_zone_mgmt(BlockDriverState *bs, zone_op op,
> +                                   int64_t offset, int64_t len);
> +
>  int bdrv_co_pdiscard(BdrvChild *child, int64_t offset, int64_t bytes);
>  bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs);
>  int bdrv_block_status(BlockDriverState *bs, int64_t offset,
> @@ -289,6 +296,12 @@ bdrv_readv_vmstate(BlockDriverState *bs, QEMUIOVector 
> *qiov, int64_t pos);
>  int generated_co_wrapper
>  bdrv_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos);
>
> +int generated_co_wrapper
> +blk_zone_report(BlockBackend *blk, int64_t offset, int64_t *nr_zones,
> +                BlockZoneDescriptor *zones);
> +int generated_co_wrapper
> +blk_zone_mgmt(BlockBackend *blk, enum zone_op op, int64_t offset, int64_t 
> len);
> +
>  /**
>   * bdrv_parent_drained_begin_single:
>   *
> diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
> index 2f0d8ac25a..a88fa322d2 100644
> --- a/qemu-io-cmds.c
> +++ b/qemu-io-cmds.c
> @@ -1706,6 +1706,144 @@ 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, nr_zones;
> +
> +    ++optind;
> +    offset = cvtnum(argv[optind]);
> +    ++optind;
> +    nr_zones = cvtnum(argv[optind]);
> +
> +    g_autofree BlockZoneDescriptor *zones = NULL;
> +    zones = g_new(BlockZoneDescriptor, nr_zones);
> +    ret = blk_zone_report(blk, offset, &nr_zones, zones);
> +    if (ret < 0) {
> +        printf("zone report failed: %s\n", strerror(-ret));
> +    } else {
> +        for (int i = 0; i < nr_zones; ++i) {
> +            printf("start: 0x%" PRIx64 ", len 0x%" PRIx64 ", "
> +                   "cap"" 0x%" PRIx64 ",wptr 0x%" PRIx64 ", "
> +                   "zcond:%u, [type: %u]\n",
> +                   zones[i].start, zones[i].length, zones[i].cap, 
> zones[i].wp,
> +                   zones[i].cond, zones[i].type);
> +        }
> +    }
> +    return ret;
> +}
> +
> +static const cmdinfo_t zone_report_cmd = {
> +        .name = "zone_report",
> +        .altname = "zp",
> +        .cfunc = zone_report_f,
> +        .argmin = 2,
> +        .argmax = 2,
> +        .args = "offset number",
> +        .oneline = "report zone information",
> +};
> +
> +static int zone_open_f(BlockBackend *blk, int argc, char **argv)
> +{
> +    int ret;
> +    int64_t offset, len;
> +    ++optind;
> +    offset = cvtnum(argv[optind]);
> +    ++optind;
> +    len = cvtnum(argv[optind]);
> +    ret = blk_zone_mgmt(blk, zone_open, offset, len);

Please name enum constants in all caps: BDRV_ZONE_OPEN or BDRV_ZO_OPEN.