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

[Stefan Hajnoczi <stefanha@gmail.com>]

On Fri, 7 Oct 2022 at 11:41, Markus Armbruster <armbru@redhat.com> wrote:
>
> 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?

Yes, will fix in the next revision. Thanks!
>
> >
> > 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?

Yes! Alberto tried to run it earlier today and hit this problem. Will
fix in the next revision:

diff --git a/qapi/block-core.json b/qapi/block-core.json
index 6c6ae2885c..d752e8550d 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -4373,6 +4373,8 @@
       'null-aio':   'BlockdevOptionsNull',
       'null-co':    'BlockdevOptionsNull',
       'nvme':       'BlockdevOptionsNVMe',
+      'nvme-io_uring': { 'type': 'BlockdevOptionsNvmeIoUring',
+                         'if': 'CONFIG_BLKIO' },
       'parallels':  'BlockdevOptionsGenericFormat',
       'preallocate':'BlockdevOptionsPreallocate',
       'qcow2':      'BlockdevOptionsQcow2',