Re: [Qemu-devel] [PATCH v4 for-4.0 0/7] vhost-user-blk: Add support for backend reconnecting

[Yongji Xie]

On Thu, 10 Jan 2019 at 18:39, Marc-André Lureau
<address@hidden> wrote:
>
> Hi
>
> On Wed, Jan 9, 2019 at 3:28 PM <address@hidden> wrote:
> >
> > From: Xie Yongji <address@hidden>
> >
> > This patchset is aimed at supporting qemu to reconnect
> > vhost-user-blk backend after vhost-user-blk backend crash or
> > restart.
> >
> > The patch 1 uses exisiting wait/nowait options to make QEMU not
> > do a connect on client sockets during initialization of the chardev.
> >
> > The patch 2 introduces two new messages VHOST_USER_GET_INFLIGHT_FD
> > and VHOST_USER_SET_INFLIGHT_FD to support providing shared
> > memory to backend.
> >
> > The patch 3,4 are the corresponding libvhost-user patches of
> > patch 2. Make libvhost-user support VHOST_USER_GET_INFLIGHT_FD
> > and VHOST_USER_SET_INFLIGHT_FD.
> >
> > The patch 5 allows vhost-user-blk to use the two new messages
> > to get/set inflight buffer from/to backend.
> >
> > The patch 6 supports vhost-user-blk to reconnect backend when
> > connection closed.
> >
> > The patch 7 introduces VHOST_USER_PROTOCOL_F_SLAVE_SHMFD
> > to vhost-user-blk backend which is used to tell qemu that
> > we support reconnecting now.
> >
> > To use it, we could start qemu with:
> >
> > qemu-system-x86_64 \
> >         -chardev 
> > socket,id=char0,path=/path/vhost.socket,nowait,reconnect=1, \
> >         -device vhost-user-blk-pci,chardev=char0 \
> >
> > and start vhost-user-blk backend with:
> >
> > vhost-user-blk -b /path/file -s /path/vhost.socket
> >
> > Then we can restart vhost-user-blk at any time during VM running.
> >
> > V3 to V4:
> > - Drop messages VHOST_USER_GET_SHM_SIZE and VHOST_USER_SET_SHM_FD
> > - Introduce two new messages VHOST_USER_GET_INFLIGHT_FD
> >   and VHOST_USER_SET_INFLIGHT_FD
> > - Allocate inflight buffer in backend rather than in qemu
> > - Document a recommended format for inflight buffer
> >
> > V2 to V3:
> > - Using exisiting wait/nowait options to control connection on
> >   client sockets instead of introducing "disconnected" option.
> > - Support the case that vhost-user backend restart during initialzation
> >   of vhost-user-blk device.
> >
> > V1 to V2:
> > - Introduce "disconnected" option for chardev instead of reuse "wait"
> >   option
> > - Support the case that QEMU starts before vhost-user backend
> > - Drop message VHOST_USER_SET_VRING_INFLIGHT
> > - Introduce two new messages VHOST_USER_GET_SHM_SIZE
> >   and VHOST_USER_SET_SHM_FD
> >
> > Xie Yongji (7):
> >   char-socket: Enable "nowait" option on client sockets
>
> This patch breaks make check.
>
> It would be nice to add a test for the new nowait behaviour.
>

Oh, sorry. I'll fix this issue and add one test for "nowait" option. Thank you!

Thanks,
Yongji