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Re: [PATCH 3/5] vduse-blk: implements vduse-blk export
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From: |
Yongji Xie |
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Subject: |
Re: [PATCH 3/5] vduse-blk: implements vduse-blk export |
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Date: |
Tue, 8 Feb 2022 14:56:51 +0800 |
On Mon, Feb 7, 2022 at 10:15 PM Stefan Hajnoczi <stefanha@redhat.com> wrote:
>
> On Tue, Jan 25, 2022 at 09:17:58PM +0800, Xie Yongji wrote:
> > This implements a VDUSE block backends based on
> > the libvduse library. We can use it to export the BDSs
> > for both VM and container (host) usage.
> >
> > The new command-line syntax is:
> >
> > $ qemu-storage-daemon \
> > --blockdev file,node-name=drive0,filename=test.img \
> > --export vduse-blk,node-name=drive0,id=vduse-export0,writable=on
> >
> > After the qemu-storage-daemon started, we need to use
> > the "vdpa" command to attach the device to vDPA bus:
> >
> > $ vdpa dev add name vduse-export0 mgmtdev vduse
> >
> > Also the device must be removed via the "vdpa" command
> > before we stop the qemu-storage-daemon.
> >
> > Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
> > ---
> > block/export/export.c | 6 +
> > block/export/meson.build | 5 +
> > block/export/vduse-blk.c | 427 ++++++++++++++++++++++++++++++++++
> > block/export/vduse-blk.h | 20 ++
> > meson.build | 13 ++
> > meson_options.txt | 2 +
> > qapi/block-export.json | 24 +-
> > scripts/meson-buildoptions.sh | 4 +
> > 8 files changed, 499 insertions(+), 2 deletions(-)
> > create mode 100644 block/export/vduse-blk.c
> > create mode 100644 block/export/vduse-blk.h
> >
> > diff --git a/block/export/export.c b/block/export/export.c
> > index 6d3b9964c8..00dd505540 100644
> > --- a/block/export/export.c
> > +++ b/block/export/export.c
> > @@ -26,6 +26,9 @@
> > #ifdef CONFIG_VHOST_USER_BLK_SERVER
> > #include "vhost-user-blk-server.h"
> > #endif
> > +#ifdef CONFIG_VDUSE_BLK_EXPORT
> > +#include "vduse-blk.h"
> > +#endif
> >
> > static const BlockExportDriver *blk_exp_drivers[] = {
> > &blk_exp_nbd,
> > @@ -35,6 +38,9 @@ static const BlockExportDriver *blk_exp_drivers[] = {
> > #ifdef CONFIG_FUSE
> > &blk_exp_fuse,
> > #endif
> > +#ifdef CONFIG_VDUSE_BLK_EXPORT
> > + &blk_exp_vduse_blk,
> > +#endif
> > };
> >
> > /* Only accessed from the main thread */
> > diff --git a/block/export/meson.build b/block/export/meson.build
> > index 0a08e384c7..cf311d2b1b 100644
> > --- a/block/export/meson.build
> > +++ b/block/export/meson.build
> > @@ -5,3 +5,8 @@ if have_vhost_user_blk_server
> > endif
> >
> > blockdev_ss.add(when: fuse, if_true: files('fuse.c'))
> > +
> > +if have_vduse_blk_export
> > + blockdev_ss.add(files('vduse-blk.c'))
> > + blockdev_ss.add(libvduse)
> > +endif
> > diff --git a/block/export/vduse-blk.c b/block/export/vduse-blk.c
> > new file mode 100644
> > index 0000000000..5a8d289685
> > --- /dev/null
> > +++ b/block/export/vduse-blk.c
> > @@ -0,0 +1,427 @@
> > +/*
> > + * Export QEMU block device via VDUSE
> > + *
> > + * Copyright (C) 2022 Bytedance Inc. and/or its affiliates. All rights
> > reserved.
> > + * Portions of codes and concepts borrowed from vhost-user-blk-server.c,
> > so:
> > + * Copyright (c) 2020 Red Hat, Inc.
> > + *
> > + * Author:
> > + * Xie Yongji <xieyongji@bytedance.com>
> > + * Coiby Xu <coiby.xu@gmail.com>
> > + *
> > + * This work is licensed under the terms of the GNU GPL, version 2 or
> > + * later. See the COPYING file in the top-level directory.
> > + */
> > +
> > +#include <sys/eventfd.h>
> > +
> > +#include "qemu/osdep.h"
> > +#include "qapi/error.h"
> > +#include "sysemu/block-backend.h"
> > +#include "block/export.h"
> > +#include "qemu/error-report.h"
> > +#include "util/block-helpers.h"
> > +#include "subprojects/libvduse/libvduse.h"
> > +
> > +#include "standard-headers/linux/virtio_ring.h"
> > +#include "standard-headers/linux/virtio_blk.h"
> > +
> > +#define VIRTIO_BLK_SECTOR_BITS 9
> > +#define VIRTIO_BLK_SECTOR_SIZE (1ULL << VIRTIO_BLK_SECTOR_BITS)
> > +
> > +#define VDUSE_DEFAULT_NUM_QUEUE 1
> > +#define VDUSE_DEFAULT_QUEUE_SIZE 128
>
> QEMU's virtio-blk emulation has increased this limit to 256 for better
> performance with large block size I/O patterns. I think it would be okay
> to increase it here too.
>
Sure.
> > +
> > +typedef struct VduseBlkExport {
> > + BlockExport export;
> > + VduseDev *dev;
> > + uint16_t num_queues;
> > + uint32_t blk_size;
> > + bool writable;
> > +} VduseBlkExport;
> > +
> > +struct virtio_blk_inhdr {
> > + unsigned char status;
> > +};
> > +
> > +typedef struct VduseBlkReq {
> > + VduseVirtqElement elem;
> > + int64_t sector_num;
> > + size_t in_len;
> > + struct virtio_blk_inhdr *in;
> > + struct virtio_blk_outhdr out;
> > + VduseVirtq *vq;
> > +} VduseBlkReq;
> > +
> > +static void vduse_blk_req_complete(VduseBlkReq *req)
> > +{
> > + vduse_queue_push(req->vq, &req->elem, req->in_len);
> > + vduse_queue_notify(req->vq);
> > +
> > + free(req);
> > +}
> > +
> > +static bool vduse_blk_sect_range_ok(VduseBlkExport *vblk_exp,
> > + uint64_t sector, size_t size)
> > +{
> > + uint64_t nb_sectors;
> > + uint64_t total_sectors;
> > +
> > + if (size % VIRTIO_BLK_SECTOR_SIZE) {
> > + return false;
> > + }
> > +
> > + nb_sectors = size >> VIRTIO_BLK_SECTOR_BITS;
> > +
> > + QEMU_BUILD_BUG_ON(BDRV_SECTOR_SIZE != VIRTIO_BLK_SECTOR_SIZE);
> > + if (nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
> > + return false;
> > + }
> > + if ((sector << VIRTIO_BLK_SECTOR_BITS) % vblk_exp->blk_size) {
> > + return false;
> > + }
> > + blk_get_geometry(vblk_exp->export.blk, &total_sectors);
> > + if (sector > total_sectors || nb_sectors > total_sectors - sector) {
> > + return false;
> > + }
> > + return true;
> > +}
> > +
> > +static void coroutine_fn vduse_blk_virtio_process_req(void *opaque)
> > +{
> > + VduseBlkReq *req = opaque;
> > + VduseVirtq *vq = req->vq;
> > + VduseDev *dev = vduse_queue_get_dev(vq);
> > + VduseBlkExport *vblk_exp = vduse_dev_get_priv(dev);
> > + BlockBackend *blk = vblk_exp->export.blk;
> > + VduseVirtqElement *elem = &req->elem;
> > + struct iovec *in_iov = elem->in_sg;
> > + struct iovec *out_iov = elem->out_sg;
> > + unsigned in_num = elem->in_num;
> > + unsigned out_num = elem->out_num;
> > + uint32_t type;
> > +
> > + if (elem->out_num < 1 || elem->in_num < 1) {
> > + error_report("virtio-blk request missing headers");
> > + goto err;
> > + }
> > +
> > + if (unlikely(iov_to_buf(out_iov, out_num, 0, &req->out,
> > + sizeof(req->out)) != sizeof(req->out))) {
> > + error_report("virtio-blk request outhdr too short");
> > + goto err;
> > + }
> > +
> > + iov_discard_front(&out_iov, &out_num, sizeof(req->out));
> > +
> > + if (in_iov[in_num - 1].iov_len < sizeof(struct virtio_blk_inhdr)) {
> > + error_report("virtio-blk request inhdr too short");
> > + goto err;
> > + }
> > +
> > + /* We always touch the last byte, so just see how big in_iov is. */
> > + req->in_len = iov_size(in_iov, in_num);
> > + req->in = (void *)in_iov[in_num - 1].iov_base
> > + + in_iov[in_num - 1].iov_len
> > + - sizeof(struct virtio_blk_inhdr);
> > + iov_discard_back(in_iov, &in_num, sizeof(struct virtio_blk_inhdr));
> > +
> > + type = le32_to_cpu(req->out.type);
> > + switch (type & ~VIRTIO_BLK_T_BARRIER) {
> > + case VIRTIO_BLK_T_IN:
> > + case VIRTIO_BLK_T_OUT: {
> > + QEMUIOVector qiov;
> > + int64_t offset;
> > + ssize_t ret = 0;
> > + bool is_write = type & VIRTIO_BLK_T_OUT;
> > + req->sector_num = le64_to_cpu(req->out.sector);
> > +
> > + if (is_write && !vblk_exp->writable) {
> > + req->in->status = VIRTIO_BLK_S_IOERR;
> > + break;
> > + }
> > +
> > + if (is_write) {
> > + qemu_iovec_init_external(&qiov, out_iov, out_num);
> > + } else {
> > + qemu_iovec_init_external(&qiov, in_iov, in_num);
> > + }
> > +
> > + if (unlikely(!vduse_blk_sect_range_ok(vblk_exp,
> > + req->sector_num,
> > + qiov.size))) {
> > + req->in->status = VIRTIO_BLK_S_IOERR;
> > + break;
> > + }
> > +
> > + offset = req->sector_num << VIRTIO_BLK_SECTOR_BITS;
> > +
> > + if (is_write) {
> > + ret = blk_co_pwritev(blk, offset, qiov.size, &qiov, 0);
> > + } else {
> > + ret = blk_co_preadv(blk, offset, qiov.size, &qiov, 0);
> > + }
> > + if (ret >= 0) {
> > + req->in->status = VIRTIO_BLK_S_OK;
> > + } else {
> > + req->in->status = VIRTIO_BLK_S_IOERR;
> > + }
> > + break;
> > + }
> > + case VIRTIO_BLK_T_FLUSH:
> > + if (blk_co_flush(blk) == 0) {
> > + req->in->status = VIRTIO_BLK_S_OK;
> > + } else {
> > + req->in->status = VIRTIO_BLK_S_IOERR;
> > + }
> > + break;
> > + case VIRTIO_BLK_T_GET_ID: {
> > + size_t size = MIN(iov_size(&elem->in_sg[0], in_num),
> > + VIRTIO_BLK_ID_BYTES);
> > + snprintf(elem->in_sg[0].iov_base, size, "%s", vblk_exp->export.id);
> > + req->in->status = VIRTIO_BLK_S_OK;
> > + break;
> > + }
> > + default:
> > + req->in->status = VIRTIO_BLK_S_UNSUPP;
> > + break;
> > + }
> > +
> > + vduse_blk_req_complete(req);
> > + return;
> > +
> > +err:
> > + free(req);
> > +}
> > +
> > +static void vduse_blk_vq_handler(VduseDev *dev, VduseVirtq *vq)
> > +{
> > + while (1) {
> > + VduseBlkReq *req;
> > +
> > + req = vduse_queue_pop(vq, sizeof(VduseBlkReq));
> > + if (!req) {
> > + break;
> > + }
> > + req->vq = vq;
> > +
> > + Coroutine *co =
> > + qemu_coroutine_create(vduse_blk_virtio_process_req, req);
> > + qemu_coroutine_enter(co);
> > + }
> > +}
> > +
> > +static void on_vduse_vq_kick(void *opaque)
> > +{
> > + VduseVirtq *vq = opaque;
> > + VduseDev *dev = vduse_queue_get_dev(vq);
> > + int fd = vduse_queue_get_fd(vq);
> > + eventfd_t kick_data;
> > +
> > + if (eventfd_read(fd, &kick_data) == -1) {
> > + error_report("failed to read data from eventfd");
> > + return;
> > + }
> > +
> > + vduse_blk_vq_handler(dev, vq);
> > +}
> > +
> > +static void vduse_blk_enable_queue(VduseDev *dev, VduseVirtq *vq)
> > +{
> > + VduseBlkExport *vblk_exp = vduse_dev_get_priv(dev);
> > +
> > + aio_set_fd_handler(vblk_exp->export.ctx, vduse_queue_get_fd(vq),
> > + true, on_vduse_vq_kick, NULL, NULL, NULL, vq);
> > +}
> > +
> > +static void vduse_blk_disable_queue(VduseDev *dev, VduseVirtq *vq)
> > +{
> > + VduseBlkExport *vblk_exp = vduse_dev_get_priv(dev);
> > +
> > + aio_set_fd_handler(vblk_exp->export.ctx, vduse_queue_get_fd(vq),
> > + true, NULL, NULL, NULL, NULL, NULL);
> > +}
> > +
> > +static const VduseOps vduse_blk_ops = {
> > + .enable_queue = vduse_blk_enable_queue,
> > + .disable_queue = vduse_blk_disable_queue,
> > +};
> > +
> > +static void on_vduse_dev_kick(void *opaque)
> > +{
> > + VduseDev *dev = opaque;
> > +
> > + vduse_dev_handler(dev);
> > +}
> > +
> > +static void blk_aio_attached(AioContext *ctx, void *opaque)
> > +{
> > + VduseBlkExport *vblk_exp = opaque;
> > + int i;
> > +
> > + vblk_exp->export.ctx = ctx;
> > +
> > + aio_set_fd_handler(vblk_exp->export.ctx,
> > vduse_dev_get_fd(vblk_exp->dev),
> > + true, on_vduse_dev_kick, NULL, NULL, NULL,
> > + vblk_exp->dev);
> > +
> > + for (i = 0; i < vblk_exp->num_queues; i++) {
> > + VduseVirtq *vq = vduse_dev_get_queue(vblk_exp->dev, i);
> > + int fd = vduse_queue_get_fd(vq);
> > +
> > + if (fd < 0) {
> > + continue;
> > + }
> > + aio_set_fd_handler(vblk_exp->export.ctx, fd, true,
> > + on_vduse_vq_kick, NULL, NULL, NULL, vq);
> > + }
> > +}
> > +
> > +static void blk_aio_detach(void *opaque)
> > +{
> > + VduseBlkExport *vblk_exp = opaque;
> > + int i;
> > +
> > + for (i = 0; i < vblk_exp->num_queues; i++) {
> > + VduseVirtq *vq = vduse_dev_get_queue(vblk_exp->dev, i);
> > + int fd = vduse_queue_get_fd(vq);
> > +
> > + if (fd < 0) {
> > + continue;
> > + }
> > + aio_set_fd_handler(vblk_exp->export.ctx, fd,
> > + true, NULL, NULL, NULL, NULL, NULL);
> > + }
> > + aio_set_fd_handler(vblk_exp->export.ctx,
> > vduse_dev_get_fd(vblk_exp->dev),
> > + true, NULL, NULL, NULL, NULL, NULL);
> > + vblk_exp->export.ctx = NULL;
> > +}
> > +
> > +static int vduse_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
> > + Error **errp)
> > +{
> > + VduseBlkExport *vblk_exp = container_of(exp, VduseBlkExport, export);
> > + BlockExportOptionsVduseBlk *vblk_opts = &opts->u.vduse_blk;
> > + uint64_t logical_block_size = VIRTIO_BLK_SECTOR_SIZE;
> > + uint16_t num_queues = VDUSE_DEFAULT_NUM_QUEUE;
> > + uint16_t queue_size = VDUSE_DEFAULT_QUEUE_SIZE;
> > + Error *local_err = NULL;
> > + struct virtio_blk_config config;
>
> Please zero-initialize this with "= { 0 }" because this struct can grow
> when Linux adds virtio-blk features and our function may not have code
> to fill in the new fields.
>
Looks good to me.
> > + uint64_t features;
> > + int i;
> > +
> > + if (vblk_opts->has_num_queues) {
> > + num_queues = vblk_opts->num_queues;
> > + if (num_queues == 0) {
> > + error_setg(errp, "num-queues must be greater than 0");
> > + return -EINVAL;
> > + }
> > + }
> > +
> > + if (vblk_opts->has_queue_size) {
> > + queue_size = vblk_opts->queue_size;
> > + if (queue_size == 0) {
> > + error_setg(errp, "queue-size must be greater than 0");
> > + return -EINVAL;
> > + }
> > + }
> > +
> > + if (vblk_opts->has_logical_block_size) {
> > + logical_block_size = vblk_opts->logical_block_size;
> > + check_block_size(exp->id, "logical-block-size", logical_block_size,
> > + &local_err);
> > + if (local_err) {
> > + error_propagate(errp, local_err);
> > + return -EINVAL;
> > + }
> > + }
> > + blk_set_guest_block_size(exp->blk, logical_block_size);
> > +
> > + vblk_exp->blk_size = logical_block_size;
> > + vblk_exp->writable = opts->writable;
> > + vblk_exp->num_queues = num_queues;
> > +
> > + config.capacity =
> > + cpu_to_le64(blk_getlength(exp->blk) >> VIRTIO_BLK_SECTOR_BITS);
> > + config.seg_max = cpu_to_le32(queue_size - 2);
>
> What is queue_size is 1 or 2?
>
OK, will validate the queue_size in v2.
> > + config.size_max = cpu_to_le32(0);
> > + config.min_io_size = cpu_to_le16(1);
> > + config.opt_io_size = cpu_to_le32(1);
> > + config.num_queues = cpu_to_le16(num_queues);
> > + config.blk_size = cpu_to_le32(logical_block_size);
> > +
> > + features = (1ULL << VIRTIO_F_IOMMU_PLATFORM) |
> > + (1ULL << VIRTIO_F_VERSION_1) |
> > + (1ULL << VIRTIO_RING_F_EVENT_IDX) |
> > + (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
> > + (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
> > + (1ULL << VIRTIO_BLK_F_SIZE_MAX) |
> > + (1ULL << VIRTIO_BLK_F_SEG_MAX) |
> > + (1ULL << VIRTIO_BLK_F_TOPOLOGY) |
> > + (1ULL << VIRTIO_BLK_F_BLK_SIZE);
> > +
> > + if (num_queues > 1) {
> > + features |= 1ULL << VIRTIO_BLK_F_MQ;
> > + }
> > + if (!vblk_exp->writable) {
> > + features |= 1ULL << VIRTIO_BLK_F_RO;
> > + }
> > +
> > + vblk_exp->dev = vduse_dev_create(exp->id, 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");
> > + return -ENOMEM;
> > + }
> > +
> > + for (i = 0; i < num_queues; i++) {
> > + vduse_dev_setup_queue(vblk_exp->dev, i, queue_size);
> > + }
> > +
> > + aio_set_fd_handler(exp->ctx, vduse_dev_get_fd(vblk_exp->dev), true,
> > + on_vduse_dev_kick, NULL, NULL, NULL, vblk_exp->dev);
> > +
> > + blk_add_aio_context_notifier(exp->blk, blk_aio_attached,
> > blk_aio_detach,
> > + vblk_exp);
> > +
> > + return 0;
> > +}
> > +
> > +static void vduse_blk_exp_delete(BlockExport *exp)
> > +{
> > + VduseBlkExport *vblk_exp = container_of(exp, VduseBlkExport, export);
> > +
> > + vduse_dev_destroy(vblk_exp->dev);
> > +}
> > +
> > +static void vduse_blk_exp_request_shutdown(BlockExport *exp)
> > +{
> > + VduseBlkExport *vblk_exp = container_of(exp, VduseBlkExport, export);
> > + int i;
> > +
> > + blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
> > blk_aio_detach,
> > + vblk_exp);
> > +
> > + for (i = 0; i < vblk_exp->num_queues; i++) {
> > + VduseVirtq *vq = vduse_dev_get_queue(vblk_exp->dev, i);
> > + int fd = vduse_queue_get_fd(vq);
> > +
> > + if (fd < 0) {
> > + continue;
> > + }
> > + aio_set_fd_handler(exp->ctx, fd, true, NULL, NULL, NULL, NULL,
> > NULL);
> > + }
> > + aio_set_fd_handler(exp->ctx, vduse_dev_get_fd(vblk_exp->dev),
> > + true, NULL, NULL, NULL, NULL, NULL);
>
> Call blk_aio_detach() instead of duplicating this code?
>
Sure.
Thanks,
Yongji