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

[Yongji Xie]

On Wed, Jun 1, 2022 at 9:03 PM Stefan Hajnoczi <stefanha@redhat.com> wrote:
>
> 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.
>

OK, it makes sense to me. But we might need a default value. Any suggestions?

> >      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.

OK.

Thanks,
Yongji