Re: [PATCH v6 02/13] blkio: add libblkio block driver

[Markus Armbruster <armbru@redhat.com>]

Stefan Hajnoczi <stefanha@redhat.com> writes:

> libblkio (https://gitlab.com/libblkio/libblkio/) is a library for
> high-performance disk I/O. It currently supports io_uring,
> virtio-blk-vhost-user, and virtio-blk-vhost-vdpa with additional drivers
> under development.
>
> One of the reasons for developing libblkio is that other applications
> besides QEMU can use it. This will be particularly useful for
> virtio-blk-vhost-user which applications may wish to use for connecting
> to qemu-storage-daemon.
>
> libblkio also gives us an opportunity to develop in Rust behind a C API
> that is easy to consume from QEMU.
>
> This commit adds io_uring, virtio-blk-vhost-user, and
> virtio-blk-vhost-vdpa BlockDrivers to QEMU using libblkio. It will be
> easy to add other libblkio drivers since they will share the majority of
> code.
>
> For now I/O buffers are copied through bounce buffers if the libblkio
> driver requires it. Later commits add an optimization for
> pre-registering guest RAM to avoid bounce buffers.
>
> The syntax is:
>
>   --blockdev io_uring,node-name=drive0,filename=test.img,readonly=on|off,cache.direct=on|off
>
> and:
>
>   --blockdev virtio-blk-vhost-vdpa,node-name=drive0,path=/dev/vdpa...,readonly=on|off

The patch also adds nvme-io_uring.  Shouldn't the commit message mention
it?

>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> Acked-by: Markus Armbruster <armbru@redhat.com>
> ---
>  MAINTAINERS                   |   6 +
>  meson_options.txt             |   2 +
>  qapi/block-core.json          |  75 ++-
>  meson.build                   |   9 +
>  block/blkio.c                 | 830 ++++++++++++++++++++++++++++++++++
>  tests/qtest/modules-test.c    |   3 +
>  block/meson.build             |   1 +
>  scripts/meson-buildoptions.sh |   3 +
>  8 files changed, 925 insertions(+), 4 deletions(-)
>  create mode 100644 block/blkio.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index e1530b51a2..0dcae6168a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3403,6 +3403,12 @@ L: qemu-block@nongnu.org
>  S: Maintained
>  F: block/vdi.c
>  
> +blkio
> +M: Stefan Hajnoczi <stefanha@redhat.com>
> +L: qemu-block@nongnu.org
> +S: Maintained
> +F: block/blkio.c
> +
>  iSCSI
>  M: Ronnie Sahlberg <ronniesahlberg@gmail.com>
>  M: Paolo Bonzini <pbonzini@redhat.com>
> diff --git a/meson_options.txt b/meson_options.txt
> index 79c6af18d5..66128178bf 100644
> --- a/meson_options.txt
> +++ b/meson_options.txt
> @@ -117,6 +117,8 @@ option('bzip2', type : 'feature', value : 'auto',
>         description: 'bzip2 support for DMG images')
>  option('cap_ng', type : 'feature', value : 'auto',
>         description: 'cap_ng support')
> +option('blkio', type : 'feature', value : 'auto',
> +       description: 'libblkio block device driver')
>  option('bpf', type : 'feature', value : 'auto',
>          description: 'eBPF support')
>  option('cocoa', type : 'feature', value : 'auto',
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index f21fa235f2..6c6ae2885c 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -2951,11 +2951,18 @@
>              'file', 'snapshot-access', 'ftp', 'ftps', 'gluster',
>              {'name': 'host_cdrom', 'if': 'HAVE_HOST_BLOCK_DEVICE' },
>              {'name': 'host_device', 'if': 'HAVE_HOST_BLOCK_DEVICE' },
> -            'http', 'https', 'iscsi',
> -            'luks', 'nbd', 'nfs', 'null-aio', 'null-co', 'nvme', 'parallels',
> -            'preallocate', 'qcow', 'qcow2', 'qed', 'quorum', 'raw', 'rbd',
> +            'http', 'https',
> +            { 'name': 'io_uring', 'if': 'CONFIG_BLKIO' },
> +            'iscsi',
> +            'luks', 'nbd', 'nfs', 'null-aio', 'null-co', 'nvme',
> +            { 'name': 'nvme-io_uring', 'if': 'CONFIG_BLKIO' },

This enumeration value and ...

> +            'parallels', 'preallocate', 'qcow', 'qcow2', 'qed', 'quorum',
> +            'raw', 'rbd',
>              { 'name': 'replication', 'if': 'CONFIG_REPLICATION' },
> -            'ssh', 'throttle', 'vdi', 'vhdx', 'vmdk', 'vpc', 'vvfat' ] }
> +            'ssh', 'throttle', 'vdi', 'vhdx',
> +            { 'name': 'virtio-blk-vhost-user', 'if': 'CONFIG_BLKIO' },
> +            { 'name': 'virtio-blk-vhost-vdpa', 'if': 'CONFIG_BLKIO' },
> +            'vmdk', 'vpc', 'vvfat' ] }
>  
>  ##
>  # @BlockdevOptionsFile:
> @@ -3678,6 +3685,58 @@
>              '*debug': 'int',
>              '*logfile': 'str' } }
>  
> +##
> +# @BlockdevOptionsIoUring:
> +#
> +# Driver specific block device options for the io_uring backend.
> +#
> +# @filename: path to the image file
> +#
> +# Since: 7.2
> +##
> +{ 'struct': 'BlockdevOptionsIoUring',
> +  'data': { 'filename': 'str' },
> +  'if': 'CONFIG_BLKIO' }
> +
> +##
> +# @BlockdevOptionsNvmeIoUring:
> +#
> +# Driver specific block device options for the nvme-io_uring backend.
> +#
> +# @filename: path to the image file
> +#
> +# Since: 7.2
> +##
> +{ 'struct': 'BlockdevOptionsNvmeIoUring',
> +  'data': { 'filename': 'str' },
> +  'if': 'CONFIG_BLKIO' }

... this type aren't used in this patch.  Did you ...

> +
> +##
> +# @BlockdevOptionsVirtioBlkVhostUser:
> +#
> +# Driver specific block device options for the virtio-blk-vhost-user backend.
> +#
> +# @path: path to the vhost-user UNIX domain socket.
> +#
> +# Since: 7.2
> +##
> +{ 'struct': 'BlockdevOptionsVirtioBlkVhostUser',
> +  'data': { 'path': 'str' },
> +  'if': 'CONFIG_BLKIO' }
> +
> +##
> +# @BlockdevOptionsVirtioBlkVhostVdpa:
> +#
> +# Driver specific block device options for the virtio-blk-vhost-vdpa backend.
> +#
> +# @path: path to the vhost-vdpa character device.
> +#
> +# Since: 7.2
> +##
> +{ 'struct': 'BlockdevOptionsVirtioBlkVhostVdpa',
> +  'data': { 'path': 'str' },
> +  'if': 'CONFIG_BLKIO' }
> +
>  ##
>  # @IscsiTransport:
>  #
> @@ -4305,6 +4364,8 @@
>                         'if': 'HAVE_HOST_BLOCK_DEVICE' },
>        'http':       'BlockdevOptionsCurlHttp',
>        'https':      'BlockdevOptionsCurlHttps',
> +      'io_uring':   { 'type': 'BlockdevOptionsIoUring',
> +                      'if': 'CONFIG_BLKIO' },
>        'iscsi':      'BlockdevOptionsIscsi',
>        'luks':       'BlockdevOptionsLUKS',
>        'nbd':        'BlockdevOptionsNbd',
> @@ -4327,6 +4388,12 @@
>        'throttle':   'BlockdevOptionsThrottle',
>        'vdi':        'BlockdevOptionsGenericFormat',
>        'vhdx':       'BlockdevOptionsGenericFormat',
> +      'virtio-blk-vhost-user':
> +                    { 'type': 'BlockdevOptionsVirtioBlkVhostUser',
> +                      'if': 'CONFIG_BLKIO' },
> +      'virtio-blk-vhost-vdpa':
> +                    { 'type': 'BlockdevOptionsVirtioBlkVhostVdpa',
> +                      'if': 'CONFIG_BLKIO' },
>        'vmdk':       'BlockdevOptionsGenericCOWFormat',
>        'vpc':        'BlockdevOptionsGenericFormat',
>        'vvfat':      'BlockdevOptionsVVFAT'

... forget to add a branch here?


[...]