On Tue, Jan 14, 2020 at 10:06:16PM +0800, Coiby Xu wrote: > By making use of libvhost, multiple block device drives can be exported and > each drive can serve multiple clients simultaneously. Since vhost-user-server > needs a block drive to be created first, delay the creation of this object. > > Signed-off-by: Coiby Xu <coiby...@gmail.com> > --- > blockdev-vu.c | 1008 ++++++++++++++++++++++++++++++++++++
This file contains both vhost-user-blk code and generic vhost-user
protocol code. Please split them into two files:
1. backends/vhost-user-blk-server.c
2. util/vhost-user-server.c
(As I read and understand the code better I may have better suggestions
about where to put these source files and how to name them.)
> include/block/vhost-user.h | 46 ++
> vl.c | 4 +
> 3 files changed, 1058 insertions(+)
> create mode 100644 blockdev-vu.c
> create mode 100644 include/block/vhost-user.h
>
> diff --git a/blockdev-vu.c b/blockdev-vu.c
> new file mode 100644
> index 0000000000..45f0bb43a7
> --- /dev/null
> +++ b/blockdev-vu.c
> @@ -0,0 +1,1008 @@
> +#include "qemu/osdep.h"
> +#include "block/vhost-user.h"
> +#include "qapi/error.h"
> +#include "qapi/qapi-types-sockets.h"
> +#include "qapi/qapi-commands-block.h"
> +
> +#include "sysemu/block-backend.h"
> +#include "qemu/main-loop.h"
> +
> +#include "qemu/units.h"
> +
> +#include "block/block.h"
> +
> +#include "qom/object_interfaces.h"
> +
> +#include <sys/eventfd.h>
> +
> +#include "hw/qdev-properties.h"
> +enum {
> + VHOST_USER_BLK_MAX_QUEUES = 8,
> +};
The number of queues is hardcoded to 1 so this constant can be removed
for now.
> +
> +struct virtio_blk_inhdr {
> + unsigned char status;
> +};
> +
> +
> +static QTAILQ_HEAD(, VubDev) vub_devs = QTAILQ_HEAD_INITIALIZER(vub_devs);
I'm not sure if this list will be necessary. See my comments about
replacing the "name" property with Object's built-in "id" property.
> +
> +
> +typedef struct VubReq {
> + VuVirtqElement *elem;
> + int64_t sector_num;
> + size_t size;
> + struct virtio_blk_inhdr *in;
> + struct virtio_blk_outhdr out;
> + VuClient *client;
> + struct VuVirtq *vq;
> +} VubReq;
> +
> +static void
> +remove_watch(VuDev *vu_dev, int fd)
> +{
> + VuClient *client;
> +
> + g_assert(vu_dev);
> + g_assert(fd >= 0);
> +
> + client = container_of(vu_dev, VuClient, parent);
> + aio_set_fd_handler(client->blk->ctx, fd, false, NULL, NULL, NULL, NULL);
> +}
> +
> +static void close_client(VuClient *client)
> +{
> + vu_deinit(&client->parent);
> + /** g_source_destroy(vub_device->parent.src); */
> + client->sioc = NULL;
> + object_unref(OBJECT(client->ioc));
> + client->closed = true;
> +
> +}
> +
> +static void vub_panic_cb(VuDev *vu_dev, const char *buf)
> +{
> + if (buf) {
> + g_warning("vu_panic: %s", buf);
> + }
> +
> + VuClient *client = container_of(vu_dev, VuClient, parent);
> + if (client->blk->exit_panic) {
> + client->blk->close = true;
> + }
> + if (!client->closed) {
> + close_client(client);
> + }
> +}
> +
> +
> +static void vub_req_complete(VubReq *req)
> +{
> + VuDev *vu_dev = &req->client->parent;
> +
> + /* IO size with 1 extra status byte */
> + vu_queue_push(vu_dev, req->vq, req->elem,
> + req->size + 1);
> + vu_queue_notify(vu_dev, req->vq);
> +
> + if (req->elem) {
> + free(req->elem);
> + }
> +
> + g_free(req);
> +}
> +
> +
> +
> +static int
> +vub_discard_write_zeroes(VubReq *req, struct iovec *iov, uint32_t iovcnt,
> + uint32_t type)
> +{
> + struct virtio_blk_discard_write_zeroes *desc;
> + ssize_t size;
> + void *buf;
> +
> + size = iov_size(iov, iovcnt);
> + if (size != sizeof(*desc)) {
> + fprintf(stderr, "Invalid size %ld, expect %ld\n", size,
> sizeof(*desc));
> + return -1;
> + }
> + buf = g_new0(char, size);
> +
> + iov_to_buf_full(iov, iovcnt, 0, buf, size);
Simpler:
struct virtio_blk_discard_write_zeroes desc;
if (unlikely(iov_to_buf(iov, iovcnt, 0, &desc, sizeof(desc)) !=
sizeof(desc)) {
/* TODO handle error */
}
No heap allocation. One variable (desc) instead of two (desc and buf).
> +
> +
> + #if defined(__linux__) && defined(BLKDISCARD) && defined(BLKZEROOUT)
> + VubDev *vdev_blk;
> + VuClient *client = container_of(dev, VuClient, parent);
> + vdev_blk = client->blk;
> + desc = (struct virtio_blk_discard_write_zeroes *)buf;
> + uint64_t range[2] = { le64toh(desc->sector) << 9,
> + le32toh(desc->num_sectors) << 9 };
> + if (type == VIRTIO_BLK_T_DISCARD) {
> + if (blk_pdiscard(vdev_blk->blk, range[0], range[1]) == 0) {
> + g_free(buf);
> + return 0;
> + }
> + } else if (type == VIRTIO_BLK_T_WRITE_ZEROES) {
> + if (blk_pwrite_zeroes(vdev_blk->blk, range[0], range[1]) == 0) {
> + g_free(buf);
> + return 0;
> + }
> + }
> + #endif
> +
> + g_free(buf);
> + return -1;
> +}
> +
> +
> +static void
> +vub_flush(VubReq *req)
> +{
> + VuClient *client = req->client;
> + blk_co_flush(client->blk->backend);
> +}
Any function that calls a *_co_*() function must be marked coroutine_fn:
static void coroutine_fn
vub_flush(VubReq *req)
> +
> +
> +#define NOT_DONE 0x7fffffff /* used while emulated sync operation in
> progress */
> +typedef struct BlkRwCo {
> + BlockBackend *blk;
> + int64_t offset;
> + void *iobuf;
> + int ret;
> + BdrvRequestFlags flags;
> +} BlkRwCo;
> +
> +static void blk_read_entry(void *opaque)
> +{
> + BlkRwCo *rwco = opaque;
> + QEMUIOVector *qiov = rwco->iobuf;
> +
> + rwco->ret = blk_co_preadv(rwco->blk, rwco->offset, qiov->size,
> + qiov, rwco->flags);
> + aio_wait_kick();
> +}
> +
> +
> +static void blk_write_entry(void *opaque)
> +{
> + BlkRwCo *rwco = opaque;
> + QEMUIOVector *qiov = rwco->iobuf;
> +
> + rwco->ret = blk_co_pwritev(rwco->blk, rwco->offset, qiov->size,
> + qiov, rwco->flags);
> + aio_wait_kick();
> +}
> +
> +
> +static int blk_prw(BlockBackend *blk, QEMUIOVector *qiov, int64_t offset,
> + CoroutineEntry co_entry, BdrvRequestFlags flags)
Why is block/block-backend.c:blk_prw() duplicated here?
> +{
> +
> + BlkRwCo rwco = {
> + .blk = blk,
> + .offset = offset,
> + .iobuf = qiov,
> + .flags = flags,
> + .ret = NOT_DONE,
> + };
> +
> + if (qemu_in_coroutine()) {
> + /* Fast-path if already in coroutine context */
> + co_entry(&rwco);
> + } else {
> + Coroutine *co = qemu_coroutine_create(co_entry, &rwco);
> + bdrv_coroutine_enter(blk_bs(blk), co);
> + BDRV_POLL_WHILE(blk_bs(blk), rwco.ret == NOT_DONE);
> + }
> +
> + return rwco.ret;
> +}
> +
> +
> +static ssize_t
> +vub_rwv(VubReq *req, struct iovec *iov,
> + uint32_t iovcnt,
> + CoroutineEntry co_entry)
> +{
> + VuClient *client = req->client;
> + ssize_t rc;
> +
> + if (!iovcnt) {
> + fprintf(stderr, "Invalid Read/Write IOV count\n");
> + return -1;
> + }
> +
> + int64_t offset = req->sector_num * 512;
> + QEMUIOVector *qiov = g_new0(QEMUIOVector, 1);
> + qemu_iovec_init_external(qiov, iov, iovcnt);
> + rc = blk_prw(client->blk->backend, qiov, offset, co_entry, 0);
> +
> + req->size = iov_size(iov, iovcnt);
> + if (rc < 0) {
> + fprintf(stderr, "%s, Sector %"PRIu64", Size %lu failed with %s\n",
> + client->blk->name, req->sector_num, req->size,
> + strerror(errno));
> + return -1;
> + }
> +
> + return rc;
> +}
> +
> +static int vub_virtio_process_req(VuClient *client,
> + VuVirtq *vq)
> +{
> + VuDev *vu_dev = &client->parent;
> + VuVirtqElement *elem;
> + uint32_t type;
> + VubReq *req;
> +
> + elem = vu_queue_pop(vu_dev, vq, sizeof(VuVirtqElement) + sizeof(VubReq));
> + if (!elem) {
> + return -1;
> + }
> +
> + 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;
> + /* refer to hw/block/virtio_blk.c */
> + if (elem->out_num < 1 || elem->in_num < 1) {
> + fprintf(stderr, "virtio-blk request missing headers\n");
> + free(elem);
> + return -1;
> + }
> +
> + req = g_new0(VubReq, 1);
> + req->client = client;
> + req->vq = vq;
> + req->elem = elem;
> +
> + if (unlikely(iov_to_buf(out_iov, out_num, 0, &req->out,
> + sizeof(req->out)) != sizeof(req->out))) {
> + fprintf(stderr, "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)) {
> + fprintf(stderr, "virtio-blk request inhdr too short");
> + goto err;
> + }
> +
> + /* We always touch the last byte, so just see how big in_iov is. */
> + 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 = le32toh(req->out.type);
> + switch (type & ~VIRTIO_BLK_T_BARRIER) {
> + case VIRTIO_BLK_T_IN:
> + case VIRTIO_BLK_T_OUT: {
> + ssize_t ret = 0;
> + bool is_write = type & VIRTIO_BLK_T_OUT;
> + req->sector_num = le64toh(req->out.sector);
> + if (is_write) {
> + ret = vub_rwv(req, out_iov, out_num, blk_write_entry);
> + } else {
> + ret = vub_rwv(req, in_iov, in_num, blk_read_entry);
> + }
> + if (ret >= 0) {
> + req->in->status = VIRTIO_BLK_S_OK;
> + } else {
> + req->in->status = VIRTIO_BLK_S_IOERR;
> + }
> + vub_req_complete(req);
> + break;
> + }
> + case VIRTIO_BLK_T_FLUSH:
> + vub_flush(req);
> + req->in->status = VIRTIO_BLK_S_OK;
> + vub_req_complete(req);
> + 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", "vhost_user_blk");
> + req->in->status = VIRTIO_BLK_S_OK;
> + req->size = elem->in_sg[0].iov_len;
> + vub_req_complete(req);
> + break;
> + }
> + case VIRTIO_BLK_T_DISCARD:
> + case VIRTIO_BLK_T_WRITE_ZEROES: {
> + int rc;
> + rc = vub_discard_write_zeroes(req, &elem->out_sg[1], out_num, type);
> + if (rc == 0) {
> + req->in->status = VIRTIO_BLK_S_OK;
> + } else {
> + req->in->status = VIRTIO_BLK_S_IOERR;
> + }
> + vub_req_complete(req);
> + break;
> + }
> + default:
> + req->in->status = VIRTIO_BLK_S_UNSUPP;
> + vub_req_complete(req);
> + break;
> + }
> +
> + return 0;
> +
> +err:
> + free(elem);
> + g_free(req);
> + return -1;
> +}
> +
> +
> +static void vub_process_vq(VuDev *vu_dev, int idx)
> +{
> + VuClient *client;
> + VuVirtq *vq;
> + int ret;
> +
> + client = container_of(vu_dev, VuClient, parent);
> + assert(client);
> +
> + vq = vu_get_queue(vu_dev, idx);
> + assert(vq);
> +
> + while (1) {
> + ret = vub_virtio_process_req(client, vq);
> + if (ret) {
> + break;
> + }
> + }
> +}
> +
> +
> +static void vub_queue_set_started(VuDev *vu_dev, int idx, bool started)
> +{
> + VuVirtq *vq;
> +
> + assert(vu_dev);
> +
> + vq = vu_get_queue(vu_dev, idx);
> + vu_set_queue_handler(vu_dev, vq, started ? vub_process_vq : NULL);
> +}
> +
> +static uint64_t
> +vub_get_features(VuDev *dev)
> +{
> + uint64_t features;
> + VubDev *vdev_blk;
> +
> + VuClient *client = container_of(dev, VuClient, parent);
> + vdev_blk = client->blk;
> +
> + features = 1ull << VIRTIO_BLK_F_SIZE_MAX |
> + 1ull << VIRTIO_BLK_F_SEG_MAX |
> + 1ull << VIRTIO_BLK_F_TOPOLOGY |
> + 1ull << VIRTIO_BLK_F_BLK_SIZE |
> + 1ull << VIRTIO_BLK_F_FLUSH |
> + #if defined(__linux__) && defined(BLKDISCARD) &&
> defined(BLKZEROOUT)
> + 1ull << VIRTIO_BLK_F_DISCARD |
> + 1ull << VIRTIO_BLK_F_WRITE_ZEROES |
> + #endif
> + 1ull << VIRTIO_BLK_F_CONFIG_WCE |
> + 1ull << VIRTIO_F_VERSION_1 |
> + 1ull << VIRTIO_RING_F_INDIRECT_DESC |
> + 1ull << VIRTIO_RING_F_EVENT_IDX |
> + 1ull << VHOST_USER_F_PROTOCOL_FEATURES;
> +
> + if (!vdev_blk->writable) {
> + features |= 1ull << VIRTIO_BLK_F_RO;
> + }
> +
> + return features;
> +}
> +
> +static uint64_t
> +vub_get_protocol_features(VuDev *dev)
> +{
> + return 1ull << VHOST_USER_PROTOCOL_F_CONFIG |
> + 1ull << VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD;
> +}
> +
> +static int
> +vub_get_config(VuDev *vu_dev, uint8_t *config, uint32_t len)
> +{
> + VubDev *vdev_blk;
> +
> + VuClient *client = container_of(vu_dev, VuClient, parent);
> + vdev_blk = client->blk;
> + memcpy(config, &vdev_blk->blkcfg, len);
> +
> + return 0;
> +}
> +
> +static int
> +vub_set_config(VuDev *vu_dev, const uint8_t *data,
> + uint32_t offset, uint32_t size, uint32_t flags)
> +{
> + VubDev *vdev_blk;
> +
> + VuClient *client = container_of(vu_dev, VuClient, parent);
> + vdev_blk = client->blk;
> + uint8_t wce;
> +
> + /* don't support live migration */
> + if (flags != VHOST_SET_CONFIG_TYPE_MASTER) {
> + return -1;
> + }
> +
> +
> + if (offset != offsetof(struct virtio_blk_config, wce) ||
> + size != 1) {
> + return -1;
> + }
> +
> + wce = *data;
> + if (wce == vdev_blk->blkcfg.wce) {
> + /* Do nothing as same with old configuration */
> + return 0;
> + }
> +
> + vdev_blk->blkcfg.wce = wce;
> + blk_set_enable_write_cache(vdev_blk->backend, true);
> + return 0;
> +}
> +
> +
> +/*
> + * When the client disconnects, it send a VHOST_USER_NONE request
> + * and vu_process_message will simple call exit which cause the VM
> + * to exit abruptly.
> + * To avoid this issue, process VHOST_USER_NONE request ahead
> + * of vu_process_message.
> + *
> + */
> +static int vub_process_msg(VuDev *dev, VhostUserMsg *vmsg, int *do_reply)
> +{
> + if (vmsg->request == VHOST_USER_NONE) {
> + dev->panic(dev, "disconnect");
> + return true;
> + }
> + return false;
> +}
> +
> +static void
> +vmsg_close_fds(VhostUserMsg *vmsg)
> +{
> + int i;
> + for (i = 0; i < vmsg->fd_num; i++) {
> + close(vmsg->fds[i]);
> + }
> +}
> +
> +static bool
> +vu_message_read_co(VuDev *vu_dev, int conn_fd, VhostUserMsg *vmsg)
Why is this function called *_co()? It appears to be callable from
outside coroutine context too.
> +{
> + char control[CMSG_SPACE(VHOST_MEMORY_MAX_NREGIONS * sizeof(int))] = { };
> + struct iovec iov = {
> + .iov_base = (char *)vmsg,
> + .iov_len = VHOST_USER_HDR_SIZE,
> + };
> + struct msghdr msg = {
> + .msg_iov = &iov,
> + .msg_iovlen = 1,
> + .msg_control = control,
> + .msg_controllen = sizeof(control),
> + };
> + size_t fd_size;
> + struct cmsghdr *cmsg;
> + int rc;
> + char buffer[100];
> + VuClient *client = container_of(vu_dev, VuClient, parent);
> + QIOChannel *ioc = client->ioc;
> + do {
> + rc = recvmsg(conn_fd, &msg, 0);
> + if (rc < 0) {
> + if (errno == EAGAIN) {
> + if (qemu_in_coroutine()) {
> + qio_channel_yield(ioc, G_IO_IN);
> + } else {
> + qio_channel_wait(ioc, G_IO_IN);
> + }
> + continue;
> + } else if (errno == EINTR) {
> + continue;
> + }
> + }
> + break;
> + } while (true);
> +
> + if (rc < 0) {
> + sprintf(buffer, "Error while recvmsg: %s", strerror(errno));
> + vub_panic_cb(vu_dev, buffer);
> + return false;
> + }
> +
> + assert(rc == VHOST_USER_HDR_SIZE || rc == 0);
> +
> + vmsg->fd_num = 0;
> + for (cmsg = CMSG_FIRSTHDR(&msg);
> + cmsg != NULL;
> + cmsg = CMSG_NXTHDR(&msg, cmsg))
> + {
> + if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS)
> {
> + fd_size = cmsg->cmsg_len - CMSG_LEN(0);
> + vmsg->fd_num = fd_size / sizeof(int);
> + memcpy(vmsg->fds, CMSG_DATA(cmsg), fd_size);
> + break;
> + }
> + }
> +
> + if (vmsg->size > sizeof(vmsg->payload)) {
> + sprintf(buffer,
> + "Error: too big message request: %d, size: vmsg->size: %u, "
> + "while sizeof(vmsg->payload) = %zu\n",
> + vmsg->request, vmsg->size, sizeof(vmsg->payload));
> + vub_panic_cb(vu_dev, buffer);
> + goto fail;
> + }
> +
> + if (vmsg->size) {
> + do {
> + rc = read(conn_fd, &vmsg->payload, vmsg->size);
> + if (rc < 0) {
> + if (errno == EAGAIN) {
> + if (qemu_in_coroutine()) {
> + qio_channel_yield(ioc, G_IO_IN);
> + } else {
> + qio_channel_wait(ioc, G_IO_IN);
> + }
> + continue;
> + } else if (errno == EINTR) {
> + continue;
> + }
> + }
> + break;
> + } while (true);
> +
> + if (rc <= 0) {
> + sprintf(buffer, "Error while reading: %s", strerror(errno));
> + vub_panic_cb(vu_dev, buffer);
> + goto fail;
> + }
> +
> + assert(rc == vmsg->size);
> + }
> +
> + return true;
> +
> +fail:
> + vmsg_close_fds(vmsg);
> +
> + return false;
> +}
> +
> +static void vub_kick_cb(void *opaque)
> +{
> + vu_watch_cb_data *data = (vu_watch_cb_data *) opaque;
> + int index = data->index;
> + VuDev *dev = data->vu_dev;
> + VuVirtq *vq = &dev->vq[index];
> + int sock = vq->kick_fd;
> + eventfd_t kick_data;
> + ssize_t rc;
> +
> + rc = eventfd_read(sock, &kick_data);
> + if (rc == -1) {
> + char buffer[100];
> + sprintf(buffer, "kick eventfd_read(): %s", strerror(errno));
> + vub_panic_cb(dev, buffer);
> + g_free(data);
> + dev->remove_watch(dev, dev->vq[index].kick_fd);
> + } else {
> + if (vq->handler) {
> + vq->handler(dev, index);
> + }
> + }
> +}
This is a generic vhost-user function that is not specific to
vhost-user-blk. It should be in a different source file.
> +
> +static const VuDevIface vub_iface = {
> + .get_features = vub_get_features,
> + .queue_set_started = vub_queue_set_started,
> + .get_protocol_features = vub_get_protocol_features,
> + .get_config = vub_get_config,
> + .set_config = vub_set_config,
> + .process_msg = vub_process_msg,
> + .read_msg = vu_message_read_co,
> + .kick_callback = vub_kick_cb,
> +};
> +
> +
> +void vub_free(VubDev *vub_dev, bool called_by_QOM)
> +{
> + if (!vub_dev) {
> + return;
> + }
> +
> + blk_unref(vub_dev->backend);
> + g_free(vub_dev->name);
> + g_free(vub_dev->unix_socket);
> +
> + if (vub_dev->next.tqe_circ.tql_prev) {
> + /*
> + * if vub_dev->next.tqe_circ.tql_prev = null,
> + * vub_dev hasn't been inserted into the queue and
> + * vub_free is called by obj->instance_finalize.
> + */
> + QTAILQ_REMOVE(&vub_devs, vub_dev, next);
> + }
> + /*
> + * Needn't to free vub_dev if called by QOM
> + * because QOM will do the clean-up work.
> + */
> + if (!called_by_QOM) {
> + g_free(vub_dev);
> + }
> +}
> +
> +static coroutine_fn void vu_client_trip(void *opaque)
> +{
> + VuClient *client = opaque;
> +
> + while (!client->closed) {
> + vu_dispatch(&client->parent);
> + }
> +
> + QTAILQ_REMOVE(&client->blk->clients, client, next);
> +
> +}
> +
> +static void vu_client_start(VuClient *client)
> +{
> + Coroutine *co = qemu_coroutine_create(vu_client_trip, client);
> + qemu_coroutine_enter(co);
> +}
What is the coroutine and threading model here? This launches
vu_client_trip() in the current thread's event loop but vu_dispatch()
performs blocking I/O and will prevent the event loop from continuing.
> +
> +
> +G_STATIC_ASSERT((int)G_IO_IN == (int)VU_WATCH_IN);
> +G_STATIC_ASSERT((int)G_IO_OUT == (int)VU_WATCH_OUT);
> +G_STATIC_ASSERT((int)G_IO_PRI == (int)VU_WATCH_PRI);
> +G_STATIC_ASSERT((int)G_IO_ERR == (int)VU_WATCH_ERR);
> +G_STATIC_ASSERT((int)G_IO_HUP == (int)VU_WATCH_HUP);
> +
> +static void
> +set_watch(VuDev *vu_dev, int fd, int vu_evt,
> + vu_watch_cb_packed_data cb, void *pvt)
> +{
> + /*
> + * since aio_dispatch can only pass one user data pointer to the
> + * callback function, pack VuDev, pvt into a struct
> + */
> + VuClient *client;
> +
> + g_assert(vu_dev);
> + g_assert(fd >= 0);
> + g_assert(cb);
> + client = container_of(vu_dev, VuClient, parent);
> + vu_watch_cb_data *cb_data = g_new0(vu_watch_cb_data, 1);
> + cb_data->index = (intptr_t) pvt;
> + cb_data->vu_dev = vu_dev;
> + aio_set_fd_handler(client->blk->ctx, fd, false, (void *) cb,
> + NULL, NULL, cb_data);
> +}
> +
> +
> +void vub_accept(QIONetListener *listener, QIOChannelSocket *sioc,
> + gpointer opaque)
> +{
> + VuClient *client;
> + VubDev *vub_device = opaque;
> + client = g_new0(VuClient, 1);
Is it helpful to have a separate VuClient struct even though only a
single vhost-user client can be connected at a time? It may be simpler
to keep connection state directly in VubDev.
> +
> + if (!vu_init_packed_data(&client->parent, VHOST_USER_BLK_MAX_QUEUES,
> + sioc->fd, vub_panic_cb, set_watch,
> + remove_watch, &vub_iface)) {
> + fprintf(stderr, "Failed to initialized libvhost-user\n");
> + g_free(client);
> + return;
> + }
> +
> + client->blk = vub_device;
> + client->refcount = 1;
> + client->sioc = sioc;
> + /*
> + * increase the object reference, so cioc will not freed by
> + * qio_net_listener_channel_func which will call
> object_unref(OBJECT(sioc))
> + */
> + object_ref(OBJECT(client->sioc));
> + qio_channel_set_name(QIO_CHANNEL(sioc), "vhost-user client");
> + client->ioc = QIO_CHANNEL(sioc);
> + object_ref(OBJECT(client->ioc));
> + object_ref(OBJECT(sioc));
> +
> + qio_channel_set_blocking(QIO_CHANNEL(client->sioc), false, NULL);
> + client->closed = false;
> + QTAILQ_INSERT_TAIL(&client->blk->clients, client, next);
> + vu_client_start(client);
> +}
> +
> +
> +void
> +vub_initialize_config(BlockDriverState *bs, struct virtio_blk_config *config)
> +{
> + config->capacity = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
> + config->blk_size = BDRV_SECTOR_SIZE;
At some point this should become a configuration parameter because using
512B sectors on a native 4K sector image file results in poor
performance.
> + config->size_max = 65536;
Why 65536? hw/block/virtio-blk.c sets it to 0.
> + config->seg_max = 128 - 2;
This is okay for now but should be changed in the future.
hw/block/virtio-blk.c was recently modified to calculate seg_max based
on the virtqueue size (which is where the hardcoded 128 originally came
from). Applications that use large buffer sizes (128+ KB) benefit from
larger virtqueue sizes and seg_max.
> + config->min_io_size = 1;
> + config->opt_io_size = 1;
> + config->num_queues = 1;
> + #if defined(__linux__) && defined(BLKDISCARD) && defined(BLKZEROOUT)
> + config->max_discard_sectors = 32768;
> + config->max_discard_seg = 1;
> + config->discard_sector_alignment = config->blk_size >> 9;
> + config->max_write_zeroes_sectors = 32768;
> + config->max_write_zeroes_seg = 1;
> + #endif
> +}
> +
> +
> +static VubDev *vub_new(VubDev *vub_device, const char *name,
> + const char *unix_socket, bool writable, Error **errp)
This function does not allocate and return a new VubDev, so vub_new() is
not an accurate name for this function. The name vub_init() is clearer.
Why are name, unix_socket, and writable passed in? They are already
vub_device fields.
> +{
> +
> + BlockBackend *blk;
> +
> + /*
> + * Don't allow resize while the vhost user server is running,
> + * otherwise we don't care what happens with the node.
> + */
> + uint64_t perm = BLK_PERM_CONSISTENT_READ;
> + int ret;
> +
> + AioContext *ctx;
> +
> + BlockDriverState *bs = bdrv_lookup_bs(name,
> + name,
> + errp);
> +
> + if (!bs) {
> + error_setg(errp,
> + "No drive with name '%s'."
> + " Please find the list of names with "
> + "'info block'", name);
> + return NULL;
> + }
> +
> + if (bdrv_is_read_only(bs)) {
> + writable = false;
> + }
> +
> + if (writable) {
> + perm |= BLK_PERM_WRITE;
> + }
> +
> + ctx = bdrv_get_aio_context(bs);
> + aio_context_acquire(ctx);
> + bdrv_invalidate_cache(bs, NULL);
> + aio_context_release(ctx);
> +
> + blk = blk_new(bdrv_get_aio_context(bs), perm,
> + BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
> + BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD);
> + ret = blk_insert_bs(blk, bs, errp);
> +
> + if (ret < 0) {
> + goto fail;
> + }
> +
> +
> + blk_set_enable_write_cache(blk, false);
> +
> + blk_set_allow_aio_context_change(blk, true);
> +
> +
> + vub_device->name = g_strdup(name);
> + vub_device->unix_socket = g_strdup(unix_socket);
> + vub_device->writable = writable;
> + vub_device->blkcfg.wce = 0;
> + vub_device->backend = blk;
> + vub_device->ctx = ctx;
> + vub_initialize_config(bs, &vub_device->blkcfg);
> + return vub_device;
> +
> +fail:
> + blk_unref(blk);
> + return NULL;
> +}
> +
> +void vhost_user_server_free(VubDev *vub_device, bool called_by_QOM)
> +{
> + if (!vub_device) {
> + return;
> + }
> +
> + VuClient *client, *next;
> + QTAILQ_FOREACH_SAFE(client, &vub_device->clients, next, next) {
> + if (!client->closed) {
> + close_client(client);
> + }
> + }
> +
> + if (vub_device->listener) {
> + qio_net_listener_disconnect(vub_device->listener);
> + object_unref(OBJECT(vub_device->listener));
> + }
> + vub_free(vub_device, called_by_QOM);
> +
> +}
> +
> +
> +VubDev *vub_dev_find(const char *name)
> +{
> + VubDev *vub_device;
> + QTAILQ_FOREACH(vub_device, &vub_devs, next) {
> + if (strcmp(name, vub_device->name) == 0) {
> + return vub_device;
> + }
> + }
> +
> + return NULL;
> +}
> +
> +
> +static VubDev *vub_dev_find_by_unix_socket(const char *unix_socket)
> +{
> + VubDev *vub_device;
> + QTAILQ_FOREACH(vub_device, &vub_devs, next) {
> + if (strcmp(unix_socket, vub_device->unix_socket) == 0) {
> + return vub_device;
> + }
> + }
> +
> + return NULL;
> +}
> +
> +static void vhost_user_server_start(VubDev *vub_device, const char
> *unix_socket,
> + const char *name, bool writable,
> + Error **errp)
> +{
> +
> + if (vub_dev_find(name) || vub_dev_find_by_unix_socket(unix_socket)) {
> + error_setg(errp, "Vhost user server with name '%s' or "
> + "with socket_path '%s' has already been started",
> + name, unix_socket);
> + return;
> + }
> +
> +
> + if (!vub_new(vub_device, name, unix_socket, writable, errp)) {
> + return;
> + }
> +
> +
> + vub_device->listener = qio_net_listener_new();
> +
> + qio_net_listener_set_name(vub_device->listener,
> + "vhost-user-backend-listener");
> +
> + SocketAddress *addr = g_new0(SocketAddress, 1);
addr is never freed. This variable could live on the stack instead:
SocketAddress addr = {};
> + addr->u.q_unix.path = (char *) unix_socket;
> + addr->type = SOCKET_ADDRESS_TYPE_UNIX;
> + if (qio_net_listener_open_sync(vub_device->listener, addr, 1, errp) < 0)
> {
> + goto error;
> + }
> +
> +
> + QTAILQ_INSERT_TAIL(&vub_devs, vub_device, next);
> + QTAILQ_INIT(&vub_device->clients);
> +
> + qio_net_listener_set_client_func(vub_device->listener,
> + vub_accept,
> + vub_device,
> + NULL);
> +
> + return;
> +
> + error:
> + vub_free(vub_device, false);
> +}
> +
> +static void vu_set_block_name(Object *obj, const char *value,
> + Error **errp)
> +{
> + VubDev *vus = VHOST_USER_SERVER(obj);;
> +
> + if (vus->name) {
> + error_setg(errp, "evdev property already set");
> + return;
> + }
> +
> + vus->name = g_strdup(value);
> +}
> +
> +static char *vu_get_block_name(Object *obj, Error **errp)
> +{
> + VubDev *vus = VHOST_USER_SERVER(obj);
> + return g_strdup(vus->name);
> +}
> +
> +
> +static void vu_set_unix_socket(Object *obj, const char *value,
> + Error **errp)
> +{
> + VubDev *vus = VHOST_USER_SERVER(obj);;
> +
> + if (vus->unix_socket) {
> + error_setg(errp, "unix_socket property already set");
> + return;
> + }
> +
> + vus->unix_socket = g_strdup(value);
> + vhost_user_server_start(vus, value, vus->name,
> + vus->writable, errp);
Property setters should only perform input validation and store the
data. Actions like creating network connections, opening files, etc
should happen later in a UserCreatableClass->complete() callback.
This is necessary because vus->writable is also a property and may be
set after unix_socket. The ->complete() callback is called after all
setters so it can access the final values of all properties.
See iothread_class_init() and iothread_complete() for an example.
> +}
> +
> +static char *vu_get_unix_socket(Object *obj, Error **errp)
> +{
> + VubDev *vus = VHOST_USER_SERVER(obj);;
> + return g_strdup(vus->unix_socket);
> +}
> +
> +static bool vu_get_block_writable(Object *obj, Error **errp)
> +{
> + VubDev *vus = VHOST_USER_SERVER(obj);;
> + return vus->writable;
> +}
> +
> +static void vu_set_block_writable(Object *obj, bool value, Error **errp)
> +{
> + VubDev *vus = VHOST_USER_SERVER(obj);
> +
> + vus->writable = value;
> +}
> +
> +static void vhost_user_server_instance_init(Object *obj)
> +{
> +
> + object_property_add_bool(obj, "writable",
> + vu_get_block_writable,
> + vu_set_block_writable, NULL);
> +
> + object_property_add_str(obj, "name",
> + vu_get_block_name,
> + vu_set_block_name, NULL);
> +
> + object_property_add_str(obj, "unix_socket",
> + vu_get_unix_socket,
> + vu_set_unix_socket, NULL);
> +
> +}
> +
> +static void vhost_user_server_instance_finalize(Object *obj)
> +{
> + VubDev *vus = VHOST_USER_SERVER(obj);
> + vhost_user_server_free(vus, true);
> + /* object_del shouldn't free this object struct */
> + obj->free = NULL;
> +}
> +
> +static const TypeInfo vhost_user_server_info = {
> + .name = TYPE_VHOST_USER_SERVER,
> + .parent = TYPE_OBJECT,
> + .instance_size = sizeof(VuDev),
> + .instance_init = vhost_user_server_instance_init,
> + .instance_finalize = vhost_user_server_instance_finalize,
> + .interfaces = (InterfaceInfo[]) {
> + {TYPE_USER_CREATABLE},
> + {}
> + },
> +};
> +
> +static void vhost_user_server_register_types(void)
> +{
> + type_register_static(&vhost_user_server_info);
> +}
> +
> +type_init(vhost_user_server_register_types)
> +
> diff --git a/include/block/vhost-user.h b/include/block/vhost-user.h
> new file mode 100644
> index 0000000000..ef6d695244
> --- /dev/null
> +++ b/include/block/vhost-user.h
> @@ -0,0 +1,46 @@
> +#include "io/channel-socket.h"
> +#include "io/net-listener.h"
> +#include "contrib/libvhost-user/libvhost-user.h"
> +#include "standard-headers/linux/virtio_blk.h"
> +typedef struct VubDev VubDev;
> +typedef struct VuClient VuClient;
> +#define TYPE_VHOST_USER_SERVER "vhost-user-server"
> +
> +#define VHOST_USER_SERVER(obj) \
> + OBJECT_CHECK(VubDev, obj, TYPE_VHOST_USER_SERVER)
> +/* vhost user block device */
> +struct VubDev {
> + Object parent_obj;
> + char *name;
> + char *unix_socket;
> + bool exit_panic;
> + bool close;
> + BlockBackend *backend;
> + AioContext *ctx;
> + QIONetListener *listener;
> + QIOChannelSocket *sioc;
> + QTAILQ_HEAD(, VuClient) clients;
> + QTAILQ_ENTRY(VubDev) next;
> + struct virtio_blk_config blkcfg;
> + bool writable;
> +};
> +
> +struct VuClient {
> + VuDev parent;
> + int refcount;
> + VubDev *blk;
> + QIOChannelSocket *sioc; /* The underlying data channel */
> + QIOChannel *ioc; /* The current I/O channel */
> + QTAILQ_ENTRY(VuClient) next;
> + bool closed;
> +};
> +VubDev *vub_dev_find(const char *name);
All -object instances already have an id=ID property. There is no need
to declare a separate "name" property. Please look at iothread_by_id()
and iothread_get_id() for examples.
> +
> +void vhost_user_server_free(VubDev *vub_device, bool called_by_QOM);
> +void vub_accept(QIONetListener *listener, QIOChannelSocket *sioc,
> + gpointer opaque);
> +
> +void vub_free(VubDev *vub_dev, bool called_by_QOM);
> +
> +void vub_initialize_config(BlockDriverState *bs,
> + struct virtio_blk_config *config);
> diff --git a/vl.c b/vl.c
> index 86474a55c9..72ac506342 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -2553,6 +2553,10 @@ static bool object_create_initial(const char *type,
> QemuOpts *opts)
> }
> #endif
>
> + /* Reason: vhost-user-server property "name" */
> + if (g_str_equal(type, "vhost-user-server")) {
> + return false;
> + }
I don't understand why the "name" property introduces a creation order
dependency. It's just a string and has no dependency on other
command-line objects. Can you explain why this change is necessary?
> /*
> * Reason: filter-* property "netdev" etc.
> */
> --
> 2.24.1
>
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