Re: [PATCH v2] vduse-blk: Add name option

[Stefan Hajnoczi]

On Tue, May 31, 2022 at 05:52:21PM +0800, Xie Yongji wrote:
> Currently we use 'id' option as the name of VDUSE device.
> It's a bit confusing since we use one value for two different
> purposes: the ID to identfy the export within QEMU (must be
> distinct from any other exports in the same QEMU process, but
> can overlap with names used by other processes), and the VDUSE
> name to uniquely identify it on the host (must be distinct from
> other VDUSE devices on the same host, but can overlap with other
> export types like NBD in the same process). To make it clear,
> this patch adds a separate 'name ' option to specify the VDUSE
> name for the vduse-blk export instead.
> 
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
> ---
>  block/export/vduse-blk.c             | 9 ++++++---
>  docs/tools/qemu-storage-daemon.rst   | 5 +++--
>  qapi/block-export.json               | 7 ++++---
>  storage-daemon/qemu-storage-daemon.c | 8 ++++----
>  4 files changed, 17 insertions(+), 12 deletions(-)
> 
> diff --git a/block/export/vduse-blk.c b/block/export/vduse-blk.c
> index 3b10349173..d96993bdf5 100644
> --- a/block/export/vduse-blk.c
> +++ b/block/export/vduse-blk.c
> @@ -245,7 +245,7 @@ static int vduse_blk_exp_create(BlockExport *exp, 
> BlockExportOptions *opts,
>      }
>      vblk_exp->num_queues = num_queues;
>      vblk_exp->handler.blk = exp->blk;
> -    vblk_exp->handler.serial = exp->id;
> +    vblk_exp->handler.serial = g_strdup(vblk_opts->name);

Do we want to expose the VDUSE device name to the guest? Maybe the
serial string should be a separate parameter.

>      vblk_exp->handler.logical_block_size = logical_block_size;
>      vblk_exp->handler.writable = opts->writable;
>  
> @@ -279,22 +279,24 @@ static int vduse_blk_exp_create(BlockExport *exp, 
> BlockExportOptions *opts,
>          features |= 1ULL << VIRTIO_BLK_F_RO;
>      }
>  
> -    vblk_exp->dev = vduse_dev_create(exp->id, VIRTIO_ID_BLOCK, 0,
> +    vblk_exp->dev = vduse_dev_create(vblk_opts->name, VIRTIO_ID_BLOCK, 0,
>                                       features, num_queues,
>                                       sizeof(struct virtio_blk_config),
>                                       (char *)&config, &vduse_blk_ops,
>                                       vblk_exp);
>      if (!vblk_exp->dev) {
>          error_setg(errp, "failed to create vduse device");
> +        g_free((void *)vblk_exp->handler.serial);

serial isn't const char * anymore, it's char *. Please update the struct
field and then these casts won't be necessary anymore.

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