[v7,4/4] contrib/vhost-user-blk: introduce a vhost-user-blk sample application

Commit Message

Liu, Changpeng Dec. 13, 2017, 2:29 a.m. UTC

This commit introcudes a vhost-user-blk backend device, it uses UNIX
domain socket to communicate with QEMU. The vhost-user-blk sample
application should be used with QEMU vhost-user-blk-pci device.

To use it, complie with:
make vhost-user-blk

and start like this:
vhost-user-blk -b /dev/sdb -s /path/vhost.socket

Signed-off-by: Changpeng Liu <[e-mail]>
---
 .gitignore                              |   1 +
 Makefile                                |   3 +
 Makefile.objs                           |   1 +
 contrib/vhost-user-blk/Makefile.objs    |   1 +
 contrib/vhost-user-blk/vhost-user-blk.c | 550 ++++++++++++++++++++++++++++++++
 5 files changed, 556 insertions(+)
 create mode 100644 contrib/vhost-user-blk/Makefile.objs
 create mode 100644 contrib/vhost-user-blk/vhost-user-blk.c

Comments

Marc-André Lureau Dec. 20, 2017, 4:02 p.m. UTC | #1

Hi

On Wed, Dec 13, 2017 at 3:29 AM, Changpeng Liu <[e-mail]> wrote:
> This commit introcudes a vhost-user-blk backend device, it uses UNIX
> domain socket to communicate with QEMU. The vhost-user-blk sample
> application should be used with QEMU vhost-user-blk-pci device.
>
> To use it, complie with:
> make vhost-user-blk
>
> and start like this:
> vhost-user-blk -b /dev/sdb -s /path/vhost.socket
>
> Signed-off-by: Changpeng Liu <[e-mail]>

Looks ok overall, just a few code cleanups would be welcome,

> ---
>  .gitignore                              |   1 +
>  Makefile                                |   3 +
>  Makefile.objs                           |   1 +
>  contrib/vhost-user-blk/Makefile.objs    |   1 +
>  contrib/vhost-user-blk/vhost-user-blk.c | 550 ++++++++++++++++++++++++++++++++
>  5 files changed, 556 insertions(+)
>  create mode 100644 contrib/vhost-user-blk/Makefile.objs
>  create mode 100644 contrib/vhost-user-blk/vhost-user-blk.c
>
> diff --git a/.gitignore b/.gitignore
> index 588769b..495f854 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -55,6 +55,7 @@
>  /scsi/qemu-pr-helper
>  /vscclient
>  /vhost-user-scsi
> +/vhost-user-blk
>  /fsdev/virtfs-proxy-helper
>  *.tmp
>  *.[1-9]
> diff --git a/Makefile b/Makefile
> index ab0354c..3aad271 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -327,6 +327,7 @@ dummy := $(call unnest-vars,, \
>                  ivshmem-server-obj-y \
>                  libvhost-user-obj-y \
>                  vhost-user-scsi-obj-y \
> +                vhost-user-blk-obj-y \
>                  qga-vss-dll-obj-y \
>                  block-obj-y \
>                  block-obj-m \
> @@ -558,6 +559,8 @@ ivshmem-server$(EXESUF): $(ivshmem-server-obj-y) $(COMMON_LDADDS)
>  endif
>  vhost-user-scsi$(EXESUF): $(vhost-user-scsi-obj-y) libvhost-user.a
>         $(call LINK, $^)
> +vhost-user-blk$(EXESUF): $(vhost-user-blk-obj-y) libvhost-user.a
> +       $(call LINK, $^)
>
>  module_block.h: $(SRC_PATH)/scripts/modules/module_block.py config-host.mak
>         $(call quiet-command,$(PYTHON) $< $@ \
> diff --git a/Makefile.objs b/Makefile.objs
> index 285c6f3..ae9aef7 100644
> --- a/Makefile.objs
> +++ b/Makefile.objs
> @@ -115,6 +115,7 @@ libvhost-user-obj-y = contrib/libvhost-user/
>  vhost-user-scsi.o-cflags := $(LIBISCSI_CFLAGS)
>  vhost-user-scsi.o-libs := $(LIBISCSI_LIBS)
>  vhost-user-scsi-obj-y = contrib/vhost-user-scsi/
> +vhost-user-blk-obj-y = contrib/vhost-user-blk/
>
>  ######################################################################
>  trace-events-subdirs =
> diff --git a/contrib/vhost-user-blk/Makefile.objs b/contrib/vhost-user-blk/Makefile.objs
> new file mode 100644
> index 0000000..72e2cdc
> --- /dev/null
> +++ b/contrib/vhost-user-blk/Makefile.objs
> @@ -0,0 +1 @@
> +vhost-user-blk-obj-y = vhost-user-blk.o
> diff --git a/contrib/vhost-user-blk/vhost-user-blk.c b/contrib/vhost-user-blk/vhost-user-blk.c
> new file mode 100644
> index 0000000..841c3c3
> --- /dev/null
> +++ b/contrib/vhost-user-blk/vhost-user-blk.c
> @@ -0,0 +1,550 @@
> +/*
> + * vhost-user-blk sample application
> + *
> + * Copyright (c) 2017 Intel Corporation. All rights reserved.
> + *
> + * Author:
> + *  Changpeng Liu <[e-mail]>
> + *
> + * This work is based on the "vhost-user-scsi" sample and "virtio-blk" driver
> + * implemention by:
> + *  Felipe Franciosi <[e-mail]>
> + *  Anthony Liguori <[e-mail]>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 only.
> + * See the COPYING file in the top-level directory.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "standard-headers/linux/virtio_blk.h"
> +#include "contrib/libvhost-user/libvhost-user-glib.h"
> +#include "contrib/libvhost-user/libvhost-user.h"
> +
> +#include <glib.h>
> +
> +struct virtio_blk_inhdr {
> +    unsigned char status;
> +};
> +
> +/* vhost user block device */
> +typedef struct VubDev {
> +    VugDev parent;
> +    int blk_fd;
> +    struct virtio_blk_config blkcfg;
> +    char *blk_name;
> +    GMainLoop *loop;
> +} VubDev;
> +
> +typedef struct VubReq {
> +    VuVirtqElement *elem;
> +    int64_t sector_num;
> +    size_t size;
> +    struct virtio_blk_inhdr *in;
> +    struct virtio_blk_outhdr *out;
> +    VubDev *vdev_blk;
> +    struct VuVirtq *vq;
> +} VubReq;
> +
> +/**  refer util/iov.c  **/
> +static size_t vub_iov_size(const struct iovec *iov,
> +                              const unsigned int iov_cnt)
> +{
> +    size_t len;
> +    unsigned int i;
> +
> +    len = 0;
> +    for (i = 0; i < iov_cnt; i++) {
> +        len += iov[i].iov_len;
> +    }
> +    return len;
> +}
> +
> +static void vub_panic_cb(VuDev *vu_dev, const char *buf)
> +{
> +    VugDev *gdev;
> +    VubDev *vdev_blk;
> +
> +    assert(vu_dev);
> +
> +    gdev = container_of(vu_dev, VugDev, parent);
> +    vdev_blk = container_of(gdev, VubDev, parent);
> +    if (buf) {
> +        g_warning("vu_panic: %s", buf);
> +    }
> +
> +    g_main_loop_quit(vdev_blk->loop);
> +}
> +
> +static void vub_req_complete(VubReq *req)
> +{
> +    VugDev *gdev = &req->vdev_blk->parent;
> +    VuDev *vu_dev = &gdev->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_open(const char *file_name, bool wce)
> +{
> +    int fd;
> +    int flags = O_RDWR;
> +
> +    if (!wce) {
> +        flags |= O_DIRECT;
> +    }
> +
> +    fd = open(file_name, flags);
> +    if (fd < 0) {
> +        fprintf(stderr, "Cannot open file %s, %s\n", file_name,
> +                strerror(errno));
> +        return -1;
> +    }
> +
> +    return fd;
> +}
> +
> +static void vub_close(int fd)
> +{
> +    if (fd >= 0) {
> +        close(fd);
> +    }
> +}

Not sure that function is worth it, see below:

> +
> +static ssize_t
> +vub_readv(VubReq *req, struct iovec *iov, uint32_t iovcnt)
> +{
> +    VubDev *vdev_blk = req->vdev_blk;
> +    ssize_t rc;
> +
> +    if (!iovcnt) {
> +        fprintf(stderr, "Invalid Read IOV count\n");
> +        return -1;
> +    }
> +
> +    req->size = vub_iov_size(iov, iovcnt);
> +    rc = preadv(vdev_blk->blk_fd, iov, iovcnt, req->sector_num * 512);
> +    if (rc < 0) {
> +        fprintf(stderr, "%s, Sector %"PRIu64", Size %lu failed with %s\n",
> +                vdev_blk->blk_name, req->sector_num, req->size,
> +                strerror(errno));
> +        return -1;
> +    }
> +
> +    return rc;
> +}
> +
> +static ssize_t
> +vub_writev(VubReq *req, struct iovec *iov, uint32_t iovcnt)
> +{
> +    VubDev *vdev_blk = req->vdev_blk;
> +    ssize_t rc;
> +
> +    if (!iovcnt) {
> +        fprintf(stderr, "Invalid Write IOV count\n");
> +        return -1;
> +    }
> +
> +    req->size = vub_iov_size(iov, iovcnt);
> +    rc = pwritev(vdev_blk->blk_fd, iov, iovcnt, req->sector_num * 512);
> +    if (rc < 0) {
> +        fprintf(stderr, "%s, Sector %"PRIu64", Size %lu failed with %s\n",
> +                vdev_blk->blk_name, req->sector_num, req->size,
> +                strerror(errno));
> +        return -1;
> +    }
> +
> +    return rc;
> +}
> +
> +static void
> +vub_flush(VubReq *req)
> +{
> +    VubDev *vdev_blk = req->vdev_blk;
> +
> +    fdatasync(vdev_blk->blk_fd);
> +}
> +
> +

2 lines?

> +static int vub_virtio_process_req(VubDev *vdev_blk,
> +                                     VuVirtq *vq)
> +{
> +    VugDev *gdev = &vdev_blk->parent;
> +    VuDev *vu_dev = &gdev->parent;
> +    VuVirtqElement *elem;
> +    uint32_t type;
> +    unsigned in_num;
> +    unsigned out_num;
> +    VubReq *req;
> +
> +    elem = vu_queue_pop(vu_dev, vq, sizeof(VuVirtqElement));
> +    if (!elem) {
> +        return -1;
> +    }
> +
> +    /* 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->vdev_blk = vdev_blk;
> +    req->vq = vq;
> +    req->elem = elem;
> +
> +    in_num = elem->in_num;
> +    out_num = elem->out_num;
> +
> +    /* don't support VIRTIO_F_ANY_LAYOUT and virtio 1.0 only */
> +    if (elem->out_sg[0].iov_len < sizeof(struct virtio_blk_outhdr)) {
> +        fprintf(stderr, "Invalid outhdr size\n");
> +        goto err;
> +    }
> +    req->out = (struct virtio_blk_outhdr *)elem->out_sg[0].iov_base;
> +    out_num--;
> +
> +    if (elem->in_sg[in_num - 1].iov_len < sizeof(struct virtio_blk_inhdr)) {
> +        fprintf(stderr, "Invalid inhdr size\n");
> +        goto err;
> +    }
> +    req->in = (struct virtio_blk_inhdr *)elem->in_sg[in_num - 1].iov_base;
> +    in_num--;
> +
> +    type = le32toh(req->out->type);
> +    switch (type & ~(VIRTIO_BLK_T_OUT | VIRTIO_BLK_T_BARRIER)) {
> +        case VIRTIO_BLK_T_IN: {
> +            ssize_t ret = 0;
> +            bool is_write = type & VIRTIO_BLK_T_OUT;
> +            req->sector_num = le64toh(req->out->sector);
> +            if (is_write) {
> +                ret  = vub_writev(req, &elem->out_sg[1], out_num);
> +            } else {
> +                ret = vub_readv(req, &elem->in_sg[0], in_num);
> +            }
> +            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(vub_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;
> +        }
> +        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)
> +{
> +    VugDev *gdev;
> +    VubDev *vdev_blk;
> +    VuVirtq *vq;
> +    int ret;
> +
> +    if ((idx < 0) || (idx >= VHOST_MAX_NR_VIRTQUEUE)) {
> +        fprintf(stderr, "VQ Index out of range: %d\n", idx);
> +        vub_panic_cb(vu_dev, NULL);
> +        return;
> +    }
> +
> +    gdev = container_of(vu_dev, VugDev, parent);
> +    vdev_blk = container_of(gdev, VubDev, parent);
> +    assert(vdev_blk);
> +
> +    vq = vu_get_queue(vu_dev, idx);
> +    assert(vq);
> +
> +    while (1) {
> +        ret = vub_virtio_process_req(vdev_blk, 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)
> +{
> +    return 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 |
> +           1ull << VIRTIO_BLK_F_CONFIG_WCE |
> +           1ull << VIRTIO_F_VERSION_1 |
> +           1ull << VHOST_USER_F_PROTOCOL_FEATURES;
> +}
> +
> +static int
> +vub_get_config(VuDev *vu_dev, uint8_t *config, uint32_t len)
> +{
> +    VugDev *gdev;
> +    VubDev *vdev_blk;
> +
> +    gdev = container_of(vu_dev, VugDev, parent);
> +    vdev_blk = container_of(gdev, VubDev, parent);
> +    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)
> +{
> +    VugDev *gdev;
> +    VubDev *vdev_blk;
> +    uint8_t wce;
> +    int fd;
> +
> +    /* don't support live migration */
> +    if (flags != VHOST_SET_CONFIG_TYPE_MASTER) {
> +        return -1;
> +    }
> +
> +    gdev = container_of(vu_dev, VugDev, parent);
> +    vdev_blk = container_of(gdev, VubDev, parent);
> +
> +    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;
> +    fprintf(stdout, "Write Cache Policy Changed\n");
> +    vub_close(vdev_blk->blk_fd);

if (vdev_blk->blk_fd >= 0)
    close(vdev_blk->blk_fd);
vdev_blk->blk_fd = -1;

> +
> +    fd = vub_open(vdev_blk->blk_name, wce);
> +    if (fd < 0) {
> +        fprintf(stderr, "Error to open block device %s\n", vdev_blk->blk_name);
> +        vdev_blk->blk_fd = -1;
> +        return -1;
> +    }
> +    vdev_blk->blk_fd = fd;
> +
> +    return 0;
> +}
> +
> +static const VuDevIface vub_iface = {
> +    .get_features = vub_get_features,
> +    .queue_set_started = vub_queue_set_started,
> +    .get_config = vub_get_config,
> +    .set_config = vub_set_config,
> +};
> +
> +static int unix_sock_new(char *unix_fn)
> +{
> +    int sock;
> +    struct sockaddr_un un;
> +    size_t len;
> +
> +    assert(unix_fn);
> +
> +    sock = socket(AF_UNIX, SOCK_STREAM, 0);
> +    if (sock <= 0) {
> +        perror("socket");
> +        return -1;
> +    }
> +
> +    un.sun_family = AF_UNIX;
> +    (void)snprintf(un.sun_path, sizeof(un.sun_path), "%s", unix_fn);
> +    len = sizeof(un.sun_family) + strlen(un.sun_path);
> +
> +    (void)unlink(unix_fn);
> +    if (bind(sock, (struct sockaddr *)&un, len) < 0) {
> +        perror("bind");
> +        goto fail;
> +    }
> +
> +    if (listen(sock, 1) < 0) {
> +        perror("listen");
> +        goto fail;
> +    }
> +
> +    return sock;
> +
> +fail:
> +    (void)close(sock);
> +
> +    return -1;
> +}
> +
> +static void vub_deinit(struct VubDev *vdev_blk)
> +{
> +    if (!vdev_blk) {
> +        return;
> +    }

Make it vub_free() to remove the g_free() after the call below?

> +
> +    if (vdev_blk->blk_fd) {
> +        vub_close(vdev_blk->blk_fd);

if (vdev_blk->blk_fd >= 0)
    close(vdev_blk->blk_fd)

& remove vub_close()

> +    }
> +}
> +
> +static uint32_t
> +vub_get_blocksize(int fd)
> +{
> +    uint32_t blocksize = 512;
> +
> +    #if defined(__linux__) && defined(BLKSSZGET)
> +    if (ioctl(fd, BLKSSZGET, &blocksize) == 0) {
> +        return blocklen;
> +    }
> +    #endif
> +
> +    return blocksize;
> +}
> +
> +static void
> +vub_initialize_config(int fd, struct virtio_blk_config *config)
> +{
> +    off64_t capacity;
> +
> +    capacity = lseek64(fd, 0, SEEK_END);
> +    config->capacity = capacity >> 9;
> +    config->blk_size = vub_get_blocksize(fd);
> +    config->size_max = 65536;
> +    config->seg_max = 128 - 2;
> +    config->min_io_size = 1;
> +    config->opt_io_size = 1;
> +    config->num_queues = 1;
> +}
> +
> +static int
> +vub_new_block(VubDev *vdev_blk, char *blk_file)

Make it vub_new() instead?

> +{
> +    vdev_blk->blk_fd = vub_open(blk_file, 0);
> +    if (vdev_blk->blk_fd  < 0) {
> +        fprintf(stderr, "Error to open block device %s\n", blk_file);
> +        return -1;
> +    }
> +    vdev_blk->blkcfg.wce = 0;
> +    vdev_blk->blk_name = blk_file;
> +
> +    /* fill virtio_blk_config with block parameters */
> +    vub_initialize_config(vdev_blk->blk_fd, &vdev_blk->blkcfg);
> +
> +    return 0;
> +}
> +
> +int main(int argc, char **argv)
> +{
> +    int opt;
> +    char *unix_socket = NULL;
> +    char *blk_file = NULL;
> +    int lsock = -1, csock = -1, rc;
> +    VubDev *vdev_blk = NULL;
> +
> +    while ((opt = getopt(argc, argv, "b:h:s:")) != -1) {
> +        switch (opt) {
> +        case 'b':
> +            blk_file = g_strdup(optarg);
> +            break;
> +        case 's':
> +            unix_socket = g_strdup(optarg);
> +            break;
> +        case 'h':
> +        default:
> +            printf("Usage: %s [-b block device or file, -s UNIX domain socket]"
> +                   " | [ -h ]\n", argv[0]);
> +            return -1;
> +        }
> +    }
> +
> +    if (!unix_socket || !blk_file) {
> +        printf("Usage: %s [-b block device or file, -s UNIX domain socket] |"
> +               " [ -h ]\n", argv[0]);
> +        return -1;
> +    }
> +
> +    lsock = unix_sock_new(unix_socket);
> +    if (lsock < 0) {
> +        goto err;
> +    }
> +
> +    csock = accept(lsock, (void *)0, (void *)0);
> +    if (csock < 0) {
> +        fprintf(stderr, "Accept error %s\n", strerror(errno));
> +        goto err;
> +    }
> +
> +    vdev_blk = g_new0(VubDev, 1);
> +    vdev_blk->loop = g_main_loop_new(NULL, FALSE);
> +
> +    rc = vub_new_block(vdev_blk, blk_file);

The 3 lines above could be simplified to be:

vub = vub_new(blk_file);

> +    if (rc) {
> +        goto err;
> +    }
> +
> +    vug_init(&vdev_blk->parent, csock, vub_panic_cb, &vub_iface);
> +
> +    g_main_loop_run(vdev_blk->loop);
> +
> +    vug_deinit(&vdev_blk->parent);
> +
> +err:
> +    if (vdev_blk) {
> +        g_main_loop_unref(vdev_blk->loop);
> +        vub_deinit(vdev_blk);
> +        g_free(vdev_blk);
> +    }

And the above block could simply be:

and this could simply be:

vub_free(vub)

> +    if (csock >= 0) {
> +        close(csock);
> +    }
> +    if (lsock >= 0) {
> +        close(lsock);
> +    }
> +    g_free(unix_socket);
> +    g_free(blk_file);
> +
> +    return 0;
> +}
> +

Please remove that extra empty line

Michael S. Tsirkin Dec. 20, 2017, 5:54 p.m. UTC | #2

On Wed, Dec 20, 2017 at 05:02:18PM +0100, Marc-André Lureau wrote:
> Hi
> 
> On Wed, Dec 13, 2017 at 3:29 AM, Changpeng Liu <[e-mail]> wrote:
> > This commit introcudes a vhost-user-blk backend device, it uses UNIX
> > domain socket to communicate with QEMU. The vhost-user-blk sample
> > application should be used with QEMU vhost-user-blk-pci device.
> >
> > To use it, complie with:
> > make vhost-user-blk
> >
> > and start like this:
> > vhost-user-blk -b /dev/sdb -s /path/vhost.socket
> >
> > Signed-off-by: Changpeng Liu <[e-mail]>
> 
> Looks ok overall, just a few code cleanups would be welcome,

I merged it by now, pls do cleanups by adding patches on top.

> > ---
> >  .gitignore                              |   1 +
> >  Makefile                                |   3 +
> >  Makefile.objs                           |   1 +
> >  contrib/vhost-user-blk/Makefile.objs    |   1 +
> >  contrib/vhost-user-blk/vhost-user-blk.c | 550 ++++++++++++++++++++++++++++++++
> >  5 files changed, 556 insertions(+)
> >  create mode 100644 contrib/vhost-user-blk/Makefile.objs
> >  create mode 100644 contrib/vhost-user-blk/vhost-user-blk.c
> >
> > diff --git a/.gitignore b/.gitignore
> > index 588769b..495f854 100644
> > --- a/.gitignore
> > +++ b/.gitignore
> > @@ -55,6 +55,7 @@
> >  /scsi/qemu-pr-helper
> >  /vscclient
> >  /vhost-user-scsi
> > +/vhost-user-blk
> >  /fsdev/virtfs-proxy-helper
> >  *.tmp
> >  *.[1-9]
> > diff --git a/Makefile b/Makefile
> > index ab0354c..3aad271 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -327,6 +327,7 @@ dummy := $(call unnest-vars,, \
> >                  ivshmem-server-obj-y \
> >                  libvhost-user-obj-y \
> >                  vhost-user-scsi-obj-y \
> > +                vhost-user-blk-obj-y \
> >                  qga-vss-dll-obj-y \
> >                  block-obj-y \
> >                  block-obj-m \
> > @@ -558,6 +559,8 @@ ivshmem-server$(EXESUF): $(ivshmem-server-obj-y) $(COMMON_LDADDS)
> >  endif
> >  vhost-user-scsi$(EXESUF): $(vhost-user-scsi-obj-y) libvhost-user.a
> >         $(call LINK, $^)
> > +vhost-user-blk$(EXESUF): $(vhost-user-blk-obj-y) libvhost-user.a
> > +       $(call LINK, $^)
> >
> >  module_block.h: $(SRC_PATH)/scripts/modules/module_block.py config-host.mak
> >         $(call quiet-command,$(PYTHON) $< $@ \
> > diff --git a/Makefile.objs b/Makefile.objs
> > index 285c6f3..ae9aef7 100644
> > --- a/Makefile.objs
> > +++ b/Makefile.objs
> > @@ -115,6 +115,7 @@ libvhost-user-obj-y = contrib/libvhost-user/
> >  vhost-user-scsi.o-cflags := $(LIBISCSI_CFLAGS)
> >  vhost-user-scsi.o-libs := $(LIBISCSI_LIBS)
> >  vhost-user-scsi-obj-y = contrib/vhost-user-scsi/
> > +vhost-user-blk-obj-y = contrib/vhost-user-blk/
> >
> >  ######################################################################
> >  trace-events-subdirs =
> > diff --git a/contrib/vhost-user-blk/Makefile.objs b/contrib/vhost-user-blk/Makefile.objs
> > new file mode 100644
> > index 0000000..72e2cdc
> > --- /dev/null
> > +++ b/contrib/vhost-user-blk/Makefile.objs
> > @@ -0,0 +1 @@
> > +vhost-user-blk-obj-y = vhost-user-blk.o
> > diff --git a/contrib/vhost-user-blk/vhost-user-blk.c b/contrib/vhost-user-blk/vhost-user-blk.c
> > new file mode 100644
> > index 0000000..841c3c3
> > --- /dev/null
> > +++ b/contrib/vhost-user-blk/vhost-user-blk.c
> > @@ -0,0 +1,550 @@
> > +/*
> > + * vhost-user-blk sample application
> > + *
> > + * Copyright (c) 2017 Intel Corporation. All rights reserved.
> > + *
> > + * Author:
> > + *  Changpeng Liu <[e-mail]>
> > + *
> > + * This work is based on the "vhost-user-scsi" sample and "virtio-blk" driver
> > + * implemention by:
> > + *  Felipe Franciosi <[e-mail]>
> > + *  Anthony Liguori <[e-mail]>
> > + *
> > + * This work is licensed under the terms of the GNU GPL, version 2 only.
> > + * See the COPYING file in the top-level directory.
> > + */
> > +
> > +#include "qemu/osdep.h"
> > +#include "standard-headers/linux/virtio_blk.h"
> > +#include "contrib/libvhost-user/libvhost-user-glib.h"
> > +#include "contrib/libvhost-user/libvhost-user.h"
> > +
> > +#include <glib.h>
> > +
> > +struct virtio_blk_inhdr {
> > +    unsigned char status;
> > +};
> > +
> > +/* vhost user block device */
> > +typedef struct VubDev {
> > +    VugDev parent;
> > +    int blk_fd;
> > +    struct virtio_blk_config blkcfg;
> > +    char *blk_name;
> > +    GMainLoop *loop;
> > +} VubDev;
> > +
> > +typedef struct VubReq {
> > +    VuVirtqElement *elem;
> > +    int64_t sector_num;
> > +    size_t size;
> > +    struct virtio_blk_inhdr *in;
> > +    struct virtio_blk_outhdr *out;
> > +    VubDev *vdev_blk;
> > +    struct VuVirtq *vq;
> > +} VubReq;
> > +
> > +/**  refer util/iov.c  **/
> > +static size_t vub_iov_size(const struct iovec *iov,
> > +                              const unsigned int iov_cnt)
> > +{
> > +    size_t len;
> > +    unsigned int i;
> > +
> > +    len = 0;
> > +    for (i = 0; i < iov_cnt; i++) {
> > +        len += iov[i].iov_len;
> > +    }
> > +    return len;
> > +}
> > +
> > +static void vub_panic_cb(VuDev *vu_dev, const char *buf)
> > +{
> > +    VugDev *gdev;
> > +    VubDev *vdev_blk;
> > +
> > +    assert(vu_dev);
> > +
> > +    gdev = container_of(vu_dev, VugDev, parent);
> > +    vdev_blk = container_of(gdev, VubDev, parent);
> > +    if (buf) {
> > +        g_warning("vu_panic: %s", buf);
> > +    }
> > +
> > +    g_main_loop_quit(vdev_blk->loop);
> > +}
> > +
> > +static void vub_req_complete(VubReq *req)
> > +{
> > +    VugDev *gdev = &req->vdev_blk->parent;
> > +    VuDev *vu_dev = &gdev->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_open(const char *file_name, bool wce)
> > +{
> > +    int fd;
> > +    int flags = O_RDWR;
> > +
> > +    if (!wce) {
> > +        flags |= O_DIRECT;
> > +    }
> > +
> > +    fd = open(file_name, flags);
> > +    if (fd < 0) {
> > +        fprintf(stderr, "Cannot open file %s, %s\n", file_name,
> > +                strerror(errno));
> > +        return -1;
> > +    }
> > +
> > +    return fd;
> > +}
> > +
> > +static void vub_close(int fd)
> > +{
> > +    if (fd >= 0) {
> > +        close(fd);
> > +    }
> > +}
> 
> Not sure that function is worth it, see below:
> 
> > +
> > +static ssize_t
> > +vub_readv(VubReq *req, struct iovec *iov, uint32_t iovcnt)
> > +{
> > +    VubDev *vdev_blk = req->vdev_blk;
> > +    ssize_t rc;
> > +
> > +    if (!iovcnt) {
> > +        fprintf(stderr, "Invalid Read IOV count\n");
> > +        return -1;
> > +    }
> > +
> > +    req->size = vub_iov_size(iov, iovcnt);
> > +    rc = preadv(vdev_blk->blk_fd, iov, iovcnt, req->sector_num * 512);
> > +    if (rc < 0) {
> > +        fprintf(stderr, "%s, Sector %"PRIu64", Size %lu failed with %s\n",
> > +                vdev_blk->blk_name, req->sector_num, req->size,
> > +                strerror(errno));
> > +        return -1;
> > +    }
> > +
> > +    return rc;
> > +}
> > +
> > +static ssize_t
> > +vub_writev(VubReq *req, struct iovec *iov, uint32_t iovcnt)
> > +{
> > +    VubDev *vdev_blk = req->vdev_blk;
> > +    ssize_t rc;
> > +
> > +    if (!iovcnt) {
> > +        fprintf(stderr, "Invalid Write IOV count\n");
> > +        return -1;
> > +    }
> > +
> > +    req->size = vub_iov_size(iov, iovcnt);
> > +    rc = pwritev(vdev_blk->blk_fd, iov, iovcnt, req->sector_num * 512);
> > +    if (rc < 0) {
> > +        fprintf(stderr, "%s, Sector %"PRIu64", Size %lu failed with %s\n",
> > +                vdev_blk->blk_name, req->sector_num, req->size,
> > +                strerror(errno));
> > +        return -1;
> > +    }
> > +
> > +    return rc;
> > +}
> > +
> > +static void
> > +vub_flush(VubReq *req)
> > +{
> > +    VubDev *vdev_blk = req->vdev_blk;
> > +
> > +    fdatasync(vdev_blk->blk_fd);
> > +}
> > +
> > +
> 
> 2 lines?
> 
> > +static int vub_virtio_process_req(VubDev *vdev_blk,
> > +                                     VuVirtq *vq)
> > +{
> > +    VugDev *gdev = &vdev_blk->parent;
> > +    VuDev *vu_dev = &gdev->parent;
> > +    VuVirtqElement *elem;
> > +    uint32_t type;
> > +    unsigned in_num;
> > +    unsigned out_num;
> > +    VubReq *req;
> > +
> > +    elem = vu_queue_pop(vu_dev, vq, sizeof(VuVirtqElement));
> > +    if (!elem) {
> > +        return -1;
> > +    }
> > +
> > +    /* 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->vdev_blk = vdev_blk;
> > +    req->vq = vq;
> > +    req->elem = elem;
> > +
> > +    in_num = elem->in_num;
> > +    out_num = elem->out_num;
> > +
> > +    /* don't support VIRTIO_F_ANY_LAYOUT and virtio 1.0 only */
> > +    if (elem->out_sg[0].iov_len < sizeof(struct virtio_blk_outhdr)) {
> > +        fprintf(stderr, "Invalid outhdr size\n");
> > +        goto err;
> > +    }
> > +    req->out = (struct virtio_blk_outhdr *)elem->out_sg[0].iov_base;
> > +    out_num--;
> > +
> > +    if (elem->in_sg[in_num - 1].iov_len < sizeof(struct virtio_blk_inhdr)) {
> > +        fprintf(stderr, "Invalid inhdr size\n");
> > +        goto err;
> > +    }
> > +    req->in = (struct virtio_blk_inhdr *)elem->in_sg[in_num - 1].iov_base;
> > +    in_num--;
> > +
> > +    type = le32toh(req->out->type);
> > +    switch (type & ~(VIRTIO_BLK_T_OUT | VIRTIO_BLK_T_BARRIER)) {
> > +        case VIRTIO_BLK_T_IN: {
> > +            ssize_t ret = 0;
> > +            bool is_write = type & VIRTIO_BLK_T_OUT;
> > +            req->sector_num = le64toh(req->out->sector);
> > +            if (is_write) {
> > +                ret  = vub_writev(req, &elem->out_sg[1], out_num);
> > +            } else {
> > +                ret = vub_readv(req, &elem->in_sg[0], in_num);
> > +            }
> > +            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(vub_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;
> > +        }
> > +        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)
> > +{
> > +    VugDev *gdev;
> > +    VubDev *vdev_blk;
> > +    VuVirtq *vq;
> > +    int ret;
> > +
> > +    if ((idx < 0) || (idx >= VHOST_MAX_NR_VIRTQUEUE)) {
> > +        fprintf(stderr, "VQ Index out of range: %d\n", idx);
> > +        vub_panic_cb(vu_dev, NULL);
> > +        return;
> > +    }
> > +
> > +    gdev = container_of(vu_dev, VugDev, parent);
> > +    vdev_blk = container_of(gdev, VubDev, parent);
> > +    assert(vdev_blk);
> > +
> > +    vq = vu_get_queue(vu_dev, idx);
> > +    assert(vq);
> > +
> > +    while (1) {
> > +        ret = vub_virtio_process_req(vdev_blk, 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)
> > +{
> > +    return 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 |
> > +           1ull << VIRTIO_BLK_F_CONFIG_WCE |
> > +           1ull << VIRTIO_F_VERSION_1 |
> > +           1ull << VHOST_USER_F_PROTOCOL_FEATURES;
> > +}
> > +
> > +static int
> > +vub_get_config(VuDev *vu_dev, uint8_t *config, uint32_t len)
> > +{
> > +    VugDev *gdev;
> > +    VubDev *vdev_blk;
> > +
> > +    gdev = container_of(vu_dev, VugDev, parent);
> > +    vdev_blk = container_of(gdev, VubDev, parent);
> > +    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)
> > +{
> > +    VugDev *gdev;
> > +    VubDev *vdev_blk;
> > +    uint8_t wce;
> > +    int fd;
> > +
> > +    /* don't support live migration */
> > +    if (flags != VHOST_SET_CONFIG_TYPE_MASTER) {
> > +        return -1;
> > +    }
> > +
> > +    gdev = container_of(vu_dev, VugDev, parent);
> > +    vdev_blk = container_of(gdev, VubDev, parent);
> > +
> > +    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;
> > +    fprintf(stdout, "Write Cache Policy Changed\n");
> > +    vub_close(vdev_blk->blk_fd);
> 
> if (vdev_blk->blk_fd >= 0)
>     close(vdev_blk->blk_fd);
> vdev_blk->blk_fd = -1;
> 
> > +
> > +    fd = vub_open(vdev_blk->blk_name, wce);
> > +    if (fd < 0) {
> > +        fprintf(stderr, "Error to open block device %s\n", vdev_blk->blk_name);
> > +        vdev_blk->blk_fd = -1;
> > +        return -1;
> > +    }
> > +    vdev_blk->blk_fd = fd;
> > +
> > +    return 0;
> > +}
> > +
> > +static const VuDevIface vub_iface = {
> > +    .get_features = vub_get_features,
> > +    .queue_set_started = vub_queue_set_started,
> > +    .get_config = vub_get_config,
> > +    .set_config = vub_set_config,
> > +};
> > +
> > +static int unix_sock_new(char *unix_fn)
> > +{
> > +    int sock;
> > +    struct sockaddr_un un;
> > +    size_t len;
> > +
> > +    assert(unix_fn);
> > +
> > +    sock = socket(AF_UNIX, SOCK_STREAM, 0);
> > +    if (sock <= 0) {
> > +        perror("socket");
> > +        return -1;
> > +    }
> > +
> > +    un.sun_family = AF_UNIX;
> > +    (void)snprintf(un.sun_path, sizeof(un.sun_path), "%s", unix_fn);
> > +    len = sizeof(un.sun_family) + strlen(un.sun_path);
> > +
> > +    (void)unlink(unix_fn);
> > +    if (bind(sock, (struct sockaddr *)&un, len) < 0) {
> > +        perror("bind");
> > +        goto fail;
> > +    }
> > +
> > +    if (listen(sock, 1) < 0) {
> > +        perror("listen");
> > +        goto fail;
> > +    }
> > +
> > +    return sock;
> > +
> > +fail:
> > +    (void)close(sock);
> > +
> > +    return -1;
> > +}
> > +
> > +static void vub_deinit(struct VubDev *vdev_blk)
> > +{
> > +    if (!vdev_blk) {
> > +        return;
> > +    }
> 
> Make it vub_free() to remove the g_free() after the call below?
> 
> > +
> > +    if (vdev_blk->blk_fd) {
> > +        vub_close(vdev_blk->blk_fd);
> 
> if (vdev_blk->blk_fd >= 0)
>     close(vdev_blk->blk_fd)
> 
> & remove vub_close()
> 
> > +    }
> > +}
> > +
> > +static uint32_t
> > +vub_get_blocksize(int fd)
> > +{
> > +    uint32_t blocksize = 512;
> > +
> > +    #if defined(__linux__) && defined(BLKSSZGET)
> > +    if (ioctl(fd, BLKSSZGET, &blocksize) == 0) {
> > +        return blocklen;
> > +    }
> > +    #endif
> > +
> > +    return blocksize;
> > +}
> > +
> > +static void
> > +vub_initialize_config(int fd, struct virtio_blk_config *config)
> > +{
> > +    off64_t capacity;
> > +
> > +    capacity = lseek64(fd, 0, SEEK_END);
> > +    config->capacity = capacity >> 9;
> > +    config->blk_size = vub_get_blocksize(fd);
> > +    config->size_max = 65536;
> > +    config->seg_max = 128 - 2;
> > +    config->min_io_size = 1;
> > +    config->opt_io_size = 1;
> > +    config->num_queues = 1;
> > +}
> > +
> > +static int
> > +vub_new_block(VubDev *vdev_blk, char *blk_file)
> 
> Make it vub_new() instead?
> 
> > +{
> > +    vdev_blk->blk_fd = vub_open(blk_file, 0);
> > +    if (vdev_blk->blk_fd  < 0) {
> > +        fprintf(stderr, "Error to open block device %s\n", blk_file);
> > +        return -1;
> > +    }
> > +    vdev_blk->blkcfg.wce = 0;
> > +    vdev_blk->blk_name = blk_file;
> > +
> > +    /* fill virtio_blk_config with block parameters */
> > +    vub_initialize_config(vdev_blk->blk_fd, &vdev_blk->blkcfg);
> > +
> > +    return 0;
> > +}
> > +
> > +int main(int argc, char **argv)
> > +{
> > +    int opt;
> > +    char *unix_socket = NULL;
> > +    char *blk_file = NULL;
> > +    int lsock = -1, csock = -1, rc;
> > +    VubDev *vdev_blk = NULL;
> > +
> > +    while ((opt = getopt(argc, argv, "b:h:s:")) != -1) {
> > +        switch (opt) {
> > +        case 'b':
> > +            blk_file = g_strdup(optarg);
> > +            break;
> > +        case 's':
> > +            unix_socket = g_strdup(optarg);
> > +            break;
> > +        case 'h':
> > +        default:
> > +            printf("Usage: %s [-b block device or file, -s UNIX domain socket]"
> > +                   " | [ -h ]\n", argv[0]);
> > +            return -1;
> > +        }
> > +    }
> > +
> > +    if (!unix_socket || !blk_file) {
> > +        printf("Usage: %s [-b block device or file, -s UNIX domain socket] |"
> > +               " [ -h ]\n", argv[0]);
> > +        return -1;
> > +    }
> > +
> > +    lsock = unix_sock_new(unix_socket);
> > +    if (lsock < 0) {
> > +        goto err;
> > +    }
> > +
> > +    csock = accept(lsock, (void *)0, (void *)0);
> > +    if (csock < 0) {
> > +        fprintf(stderr, "Accept error %s\n", strerror(errno));
> > +        goto err;
> > +    }
> > +
> > +    vdev_blk = g_new0(VubDev, 1);
> > +    vdev_blk->loop = g_main_loop_new(NULL, FALSE);
> > +
> > +    rc = vub_new_block(vdev_blk, blk_file);
> 
> The 3 lines above could be simplified to be:
> 
> vub = vub_new(blk_file);
> 
> > +    if (rc) {
> > +        goto err;
> > +    }
> > +
> > +    vug_init(&vdev_blk->parent, csock, vub_panic_cb, &vub_iface);
> > +
> > +    g_main_loop_run(vdev_blk->loop);
> > +
> > +    vug_deinit(&vdev_blk->parent);
> > +
> > +err:
> > +    if (vdev_blk) {
> > +        g_main_loop_unref(vdev_blk->loop);
> > +        vub_deinit(vdev_blk);
> > +        g_free(vdev_blk);
> > +    }
> 
> And the above block could simply be:
> 
> and this could simply be:
> 
> vub_free(vub)
> 
> > +    if (csock >= 0) {
> > +        close(csock);
> > +    }
> > +    if (lsock >= 0) {
> > +        close(lsock);
> > +    }
> > +    g_free(unix_socket);
> > +    g_free(blk_file);
> > +
> > +    return 0;
> > +}
> > +
> 
> Please remove that extra empty line
> 
> 
> 
> -- 
> Marc-André Lureau

Patch

diff --git a/.gitignore b/.gitignore
index 588769b..495f854 100644
--- a/.gitignore
+++ b/.gitignore
@@ -55,6 +55,7 @@ 
 /scsi/qemu-pr-helper
 /vscclient
 /vhost-user-scsi
+/vhost-user-blk
 /fsdev/virtfs-proxy-helper
 *.tmp
 *.[1-9]
diff --git a/Makefile b/Makefile
index ab0354c..3aad271 100644
--- a/Makefile
+++ b/Makefile
@@ -327,6 +327,7 @@  dummy := $(call unnest-vars,, \
                 ivshmem-server-obj-y \
                 libvhost-user-obj-y \
                 vhost-user-scsi-obj-y \
+                vhost-user-blk-obj-y \
                 qga-vss-dll-obj-y \
                 block-obj-y \
                 block-obj-m \
@@ -558,6 +559,8 @@  ivshmem-server$(EXESUF): $(ivshmem-server-obj-y) $(COMMON_LDADDS)
 endif
 vhost-user-scsi$(EXESUF): $(vhost-user-scsi-obj-y) libvhost-user.a
 	$(call LINK, $^)
+vhost-user-blk$(EXESUF): $(vhost-user-blk-obj-y) libvhost-user.a
+	$(call LINK, $^)
 
 module_block.h: $(SRC_PATH)/scripts/modules/module_block.py config-host.mak
 	$(call quiet-command,$(PYTHON) $< $@ \
diff --git a/Makefile.objs b/Makefile.objs
index 285c6f3..ae9aef7 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -115,6 +115,7 @@  libvhost-user-obj-y = contrib/libvhost-user/
 vhost-user-scsi.o-cflags := $(LIBISCSI_CFLAGS)
 vhost-user-scsi.o-libs := $(LIBISCSI_LIBS)
 vhost-user-scsi-obj-y = contrib/vhost-user-scsi/
+vhost-user-blk-obj-y = contrib/vhost-user-blk/
 
 ######################################################################
 trace-events-subdirs =
diff --git a/contrib/vhost-user-blk/Makefile.objs b/contrib/vhost-user-blk/Makefile.objs
new file mode 100644
index 0000000..72e2cdc
--- /dev/null
+++ b/contrib/vhost-user-blk/Makefile.objs
@@ -0,0 +1 @@ 
+vhost-user-blk-obj-y = vhost-user-blk.o
diff --git a/contrib/vhost-user-blk/vhost-user-blk.c b/contrib/vhost-user-blk/vhost-user-blk.c
new file mode 100644
index 0000000..841c3c3
--- /dev/null
+++ b/contrib/vhost-user-blk/vhost-user-blk.c
@@ -0,0 +1,550 @@ 
+/*
+ * vhost-user-blk sample application
+ *
+ * Copyright (c) 2017 Intel Corporation. All rights reserved.
+ *
+ * Author:
+ *  Changpeng Liu <[e-mail]>
+ *
+ * This work is based on the "vhost-user-scsi" sample and "virtio-blk" driver
+ * implemention by:
+ *  Felipe Franciosi <[e-mail]>
+ *  Anthony Liguori <[e-mail]>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 only.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "standard-headers/linux/virtio_blk.h"
+#include "contrib/libvhost-user/libvhost-user-glib.h"
+#include "contrib/libvhost-user/libvhost-user.h"
+
+#include <glib.h>
+
+struct virtio_blk_inhdr {
+    unsigned char status;
+};
+
+/* vhost user block device */
+typedef struct VubDev {
+    VugDev parent;
+    int blk_fd;
+    struct virtio_blk_config blkcfg;
+    char *blk_name;
+    GMainLoop *loop;
+} VubDev;
+
+typedef struct VubReq {
+    VuVirtqElement *elem;
+    int64_t sector_num;
+    size_t size;
+    struct virtio_blk_inhdr *in;
+    struct virtio_blk_outhdr *out;
+    VubDev *vdev_blk;
+    struct VuVirtq *vq;
+} VubReq;
+
+/**  refer util/iov.c  **/
+static size_t vub_iov_size(const struct iovec *iov,
+                              const unsigned int iov_cnt)
+{
+    size_t len;
+    unsigned int i;
+
+    len = 0;
+    for (i = 0; i < iov_cnt; i++) {
+        len += iov[i].iov_len;
+    }
+    return len;
+}
+
+static void vub_panic_cb(VuDev *vu_dev, const char *buf)
+{
+    VugDev *gdev;
+    VubDev *vdev_blk;
+
+    assert(vu_dev);
+
+    gdev = container_of(vu_dev, VugDev, parent);
+    vdev_blk = container_of(gdev, VubDev, parent);
+    if (buf) {
+        g_warning("vu_panic: %s", buf);
+    }
+
+    g_main_loop_quit(vdev_blk->loop);
+}
+
+static void vub_req_complete(VubReq *req)
+{
+    VugDev *gdev = &req->vdev_blk->parent;
+    VuDev *vu_dev = &gdev->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_open(const char *file_name, bool wce)
+{
+    int fd;
+    int flags = O_RDWR;
+
+    if (!wce) {
+        flags |= O_DIRECT;
+    }
+
+    fd = open(file_name, flags);
+    if (fd < 0) {
+        fprintf(stderr, "Cannot open file %s, %s\n", file_name,
+                strerror(errno));
+        return -1;
+    }
+
+    return fd;
+}
+
+static void vub_close(int fd)
+{
+    if (fd >= 0) {
+        close(fd);
+    }
+}
+
+static ssize_t
+vub_readv(VubReq *req, struct iovec *iov, uint32_t iovcnt)
+{
+    VubDev *vdev_blk = req->vdev_blk;
+    ssize_t rc;
+
+    if (!iovcnt) {
+        fprintf(stderr, "Invalid Read IOV count\n");
+        return -1;
+    }
+
+    req->size = vub_iov_size(iov, iovcnt);
+    rc = preadv(vdev_blk->blk_fd, iov, iovcnt, req->sector_num * 512);
+    if (rc < 0) {
+        fprintf(stderr, "%s, Sector %"PRIu64", Size %lu failed with %s\n",
+                vdev_blk->blk_name, req->sector_num, req->size,
+                strerror(errno));
+        return -1;
+    }
+
+    return rc;
+}
+
+static ssize_t
+vub_writev(VubReq *req, struct iovec *iov, uint32_t iovcnt)
+{
+    VubDev *vdev_blk = req->vdev_blk;
+    ssize_t rc;
+
+    if (!iovcnt) {
+        fprintf(stderr, "Invalid Write IOV count\n");
+        return -1;
+    }
+
+    req->size = vub_iov_size(iov, iovcnt);
+    rc = pwritev(vdev_blk->blk_fd, iov, iovcnt, req->sector_num * 512);
+    if (rc < 0) {
+        fprintf(stderr, "%s, Sector %"PRIu64", Size %lu failed with %s\n",
+                vdev_blk->blk_name, req->sector_num, req->size,
+                strerror(errno));
+        return -1;
+    }
+
+    return rc;
+}
+
+static void
+vub_flush(VubReq *req)
+{
+    VubDev *vdev_blk = req->vdev_blk;
+
+    fdatasync(vdev_blk->blk_fd);
+}
+
+
+static int vub_virtio_process_req(VubDev *vdev_blk,
+                                     VuVirtq *vq)
+{
+    VugDev *gdev = &vdev_blk->parent;
+    VuDev *vu_dev = &gdev->parent;
+    VuVirtqElement *elem;
+    uint32_t type;
+    unsigned in_num;
+    unsigned out_num;
+    VubReq *req;
+
+    elem = vu_queue_pop(vu_dev, vq, sizeof(VuVirtqElement));
+    if (!elem) {
+        return -1;
+    }
+
+    /* 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->vdev_blk = vdev_blk;
+    req->vq = vq;
+    req->elem = elem;
+
+    in_num = elem->in_num;
+    out_num = elem->out_num;
+
+    /* don't support VIRTIO_F_ANY_LAYOUT and virtio 1.0 only */
+    if (elem->out_sg[0].iov_len < sizeof(struct virtio_blk_outhdr)) {
+        fprintf(stderr, "Invalid outhdr size\n");
+        goto err;
+    }
+    req->out = (struct virtio_blk_outhdr *)elem->out_sg[0].iov_base;
+    out_num--;
+
+    if (elem->in_sg[in_num - 1].iov_len < sizeof(struct virtio_blk_inhdr)) {
+        fprintf(stderr, "Invalid inhdr size\n");
+        goto err;
+    }
+    req->in = (struct virtio_blk_inhdr *)elem->in_sg[in_num - 1].iov_base;
+    in_num--;
+
+    type = le32toh(req->out->type);
+    switch (type & ~(VIRTIO_BLK_T_OUT | VIRTIO_BLK_T_BARRIER)) {
+        case VIRTIO_BLK_T_IN: {
+            ssize_t ret = 0;
+            bool is_write = type & VIRTIO_BLK_T_OUT;
+            req->sector_num = le64toh(req->out->sector);
+            if (is_write) {
+                ret  = vub_writev(req, &elem->out_sg[1], out_num);
+            } else {
+                ret = vub_readv(req, &elem->in_sg[0], in_num);
+            }
+            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(vub_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;
+        }
+        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)
+{
+    VugDev *gdev;
+    VubDev *vdev_blk;
+    VuVirtq *vq;
+    int ret;
+
+    if ((idx < 0) || (idx >= VHOST_MAX_NR_VIRTQUEUE)) {
+        fprintf(stderr, "VQ Index out of range: %d\n", idx);
+        vub_panic_cb(vu_dev, NULL);
+        return;
+    }
+
+    gdev = container_of(vu_dev, VugDev, parent);
+    vdev_blk = container_of(gdev, VubDev, parent);
+    assert(vdev_blk);
+
+    vq = vu_get_queue(vu_dev, idx);
+    assert(vq);
+
+    while (1) {
+        ret = vub_virtio_process_req(vdev_blk, 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)
+{
+    return 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 |
+           1ull << VIRTIO_BLK_F_CONFIG_WCE |
+           1ull << VIRTIO_F_VERSION_1 |
+           1ull << VHOST_USER_F_PROTOCOL_FEATURES;
+}
+
+static int
+vub_get_config(VuDev *vu_dev, uint8_t *config, uint32_t len)
+{
+    VugDev *gdev;
+    VubDev *vdev_blk;
+
+    gdev = container_of(vu_dev, VugDev, parent);
+    vdev_blk = container_of(gdev, VubDev, parent);
+    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)
+{
+    VugDev *gdev;
+    VubDev *vdev_blk;
+    uint8_t wce;
+    int fd;
+
+    /* don't support live migration */
+    if (flags != VHOST_SET_CONFIG_TYPE_MASTER) {
+        return -1;
+    }
+
+    gdev = container_of(vu_dev, VugDev, parent);
+    vdev_blk = container_of(gdev, VubDev, parent);
+
+    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;
+    fprintf(stdout, "Write Cache Policy Changed\n");
+    vub_close(vdev_blk->blk_fd);
+
+    fd = vub_open(vdev_blk->blk_name, wce);
+    if (fd < 0) {
+        fprintf(stderr, "Error to open block device %s\n", vdev_blk->blk_name);
+        vdev_blk->blk_fd = -1;
+        return -1;
+    }
+    vdev_blk->blk_fd = fd;
+
+    return 0;
+}
+
+static const VuDevIface vub_iface = {
+    .get_features = vub_get_features,
+    .queue_set_started = vub_queue_set_started,
+    .get_config = vub_get_config,
+    .set_config = vub_set_config,
+};
+
+static int unix_sock_new(char *unix_fn)
+{
+    int sock;
+    struct sockaddr_un un;
+    size_t len;
+
+    assert(unix_fn);
+
+    sock = socket(AF_UNIX, SOCK_STREAM, 0);
+    if (sock <= 0) {
+        perror("socket");
+        return -1;
+    }
+
+    un.sun_family = AF_UNIX;
+    (void)snprintf(un.sun_path, sizeof(un.sun_path), "%s", unix_fn);
+    len = sizeof(un.sun_family) + strlen(un.sun_path);
+
+    (void)unlink(unix_fn);
+    if (bind(sock, (struct sockaddr *)&un, len) < 0) {
+        perror("bind");
+        goto fail;
+    }
+
+    if (listen(sock, 1) < 0) {
+        perror("listen");
+        goto fail;
+    }
+
+    return sock;
+
+fail:
+    (void)close(sock);
+
+    return -1;
+}
+
+static void vub_deinit(struct VubDev *vdev_blk)
+{
+    if (!vdev_blk) {
+        return;
+    }
+
+    if (vdev_blk->blk_fd) {
+        vub_close(vdev_blk->blk_fd);
+    }
+}
+
+static uint32_t
+vub_get_blocksize(int fd)
+{
+    uint32_t blocksize = 512;
+
+    #if defined(__linux__) && defined(BLKSSZGET)
+    if (ioctl(fd, BLKSSZGET, &blocksize) == 0) {
+        return blocklen;
+    }
+    #endif
+
+    return blocksize;
+}
+
+static void
+vub_initialize_config(int fd, struct virtio_blk_config *config)
+{
+    off64_t capacity;
+
+    capacity = lseek64(fd, 0, SEEK_END);
+    config->capacity = capacity >> 9;
+    config->blk_size = vub_get_blocksize(fd);
+    config->size_max = 65536;
+    config->seg_max = 128 - 2;
+    config->min_io_size = 1;
+    config->opt_io_size = 1;
+    config->num_queues = 1;
+}
+
+static int
+vub_new_block(VubDev *vdev_blk, char *blk_file)
+{
+    vdev_blk->blk_fd = vub_open(blk_file, 0);
+    if (vdev_blk->blk_fd  < 0) {
+        fprintf(stderr, "Error to open block device %s\n", blk_file);
+        return -1;
+    }
+    vdev_blk->blkcfg.wce = 0;
+    vdev_blk->blk_name = blk_file;
+
+    /* fill virtio_blk_config with block parameters */
+    vub_initialize_config(vdev_blk->blk_fd, &vdev_blk->blkcfg);
+
+    return 0;
+}
+
+int main(int argc, char **argv)
+{
+    int opt;
+    char *unix_socket = NULL;
+    char *blk_file = NULL;
+    int lsock = -1, csock = -1, rc;
+    VubDev *vdev_blk = NULL;
+
+    while ((opt = getopt(argc, argv, "b:h:s:")) != -1) {
+        switch (opt) {
+        case 'b':
+            blk_file = g_strdup(optarg);
+            break;
+        case 's':
+            unix_socket = g_strdup(optarg);
+            break;
+        case 'h':
+        default:
+            printf("Usage: %s [-b block device or file, -s UNIX domain socket]"
+                   " | [ -h ]\n", argv[0]);
+            return -1;
+        }
+    }
+
+    if (!unix_socket || !blk_file) {
+        printf("Usage: %s [-b block device or file, -s UNIX domain socket] |"
+               " [ -h ]\n", argv[0]);
+        return -1;
+    }
+
+    lsock = unix_sock_new(unix_socket);
+    if (lsock < 0) {
+        goto err;
+    }
+
+    csock = accept(lsock, (void *)0, (void *)0);
+    if (csock < 0) {
+        fprintf(stderr, "Accept error %s\n", strerror(errno));
+        goto err;
+    }
+
+    vdev_blk = g_new0(VubDev, 1);
+    vdev_blk->loop = g_main_loop_new(NULL, FALSE);
+
+    rc = vub_new_block(vdev_blk, blk_file);
+    if (rc) {
+        goto err;
+    }
+
+    vug_init(&vdev_blk->parent, csock, vub_panic_cb, &vub_iface);
+
+    g_main_loop_run(vdev_blk->loop);
+
+    vug_deinit(&vdev_blk->parent);
+
+err:
+    if (vdev_blk) {
+        g_main_loop_unref(vdev_blk->loop);
+        vub_deinit(vdev_blk);
+        g_free(vdev_blk);
+    }
+    if (csock >= 0) {
+        close(csock);
+    }
+    if (lsock >= 0) {
+        close(lsock);
+    }
+    g_free(unix_socket);
+    g_free(blk_file);
+
+    return 0;
+}
+