Re: [PATCH v2 11/13] block/export: convert vhost-user-blk server to block export API

[Markus Armbruster]

Stefan Hajnoczi <stefanha@redhat.com> writes:

> Use the new QAPI block exports API instead of defining our own QOM
> objects.
>
> This is a large change because the lifecycle of VuBlockDev needs to
> follow BlockExportDriver. QOM properties are replaced by QAPI options
> objects.
>
> VuBlockDev is renamed VuBlkExport and contains a BlockExport field.
> Several fields can be dropped since BlockExport already has equivalents.
>
> The file names and meson build integration will be adjusted in a future
> patch. libvhost-user should probably be built as a static library that
> is linked into QEMU instead of as a .c file that results in duplicate
> compilation.
>
> The new command-line syntax is:
>
>   $ qemu-storage-daemon \
>       --blockdev file,node-name=drive0,filename=test.img \
>       --export 
> vhost-user-blk,node-name=drive0,id=export0,unix-socket=/tmp/vhost-user-blk.sock
>
> Note that unix-socket is optional because we may wish to accept chardevs
> too in the future.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> v2:
>  * Replace str unix-socket with SocketAddress addr to match NBD and
>    support file descriptor passing
>  * Make addr mandatory [Markus]
>  * Update vhost-user-blk-test.c to use --export syntax
> ---
>  qapi/block-export.json               |  21 +-
>  block/export/vhost-user-blk-server.h |  23 +-
>  block/export/export.c                |   8 +-
>  block/export/vhost-user-blk-server.c | 452 +++++++--------------------
>  tests/qtest/vhost-user-blk-test.c    |   2 +-
>  util/vhost-user-server.c             |  10 +-
>  block/export/meson.build             |   1 +
>  block/meson.build                    |   1 -
>  8 files changed, 158 insertions(+), 360 deletions(-)
>
> diff --git a/qapi/block-export.json b/qapi/block-export.json
> index ace0d66e17..2e44625bb1 100644
> --- a/qapi/block-export.json
> +++ b/qapi/block-export.json
> @@ -84,6 +84,21 @@
>    'data': { '*name': 'str', '*description': 'str',
>              '*bitmap': 'str' } }
>  
> +##
> +# @BlockExportOptionsVhostUserBlk:
> +#
> +# A vhost-user-blk block export.
> +#
> +# @addr: The vhost-user socket on which to listen. Both 'unix' and 'fd'
> +#        SocketAddress types are supported. Passed fds must be UNIX domain
> +#        sockets.

"addr.type must be 'unix' or 'fd'" is not visible in introspection.
Awkward.  Practical problem only if other addresses ever become
available here.  Is that possible?

> +# @logical-block-size: Logical block size in bytes. Defaults to 512 bytes.
> +#
> +# Since: 5.2
> +##
> +{ 'struct': 'BlockExportOptionsVhostUserBlk',
> +  'data': { 'addr': 'SocketAddress', '*logical-block-size': 'size' } }
> +
>  ##
>  # @NbdServerAddOptions:
>  #
> @@ -180,11 +195,12 @@
>  # An enumeration of block export types
>  #
>  # @nbd: NBD export
> +# @vhost-user-blk: vhost-user-blk export (since 5.2)
>  #
>  # Since: 4.2
>  ##
>  { 'enum': 'BlockExportType',
> -  'data': [ 'nbd' ] }
> +  'data': [ 'nbd', 'vhost-user-blk' ] }
>  
>  ##
>  # @BlockExportOptions:
> @@ -213,7 +229,8 @@
>              '*writethrough': 'bool' },
>    'discriminator': 'type',
>    'data': {
> -      'nbd': 'BlockExportOptionsNbd'
> +      'nbd': 'BlockExportOptionsNbd',
> +      'vhost-user-blk': 'BlockExportOptionsVhostUserBlk'
>     } }
>  
>  ##
[...]