Re: [Qemu-devel] [PATCH v8 4/4] contrib/vhost-user-blk: introduce a vhost-user-blk sample application

[Marc-André Lureau]

On Tue, Jan 2, 2018 at 4:55 AM, Changpeng Liu <address@hidden> wrote:
> This commit introcudes a vhost-user-blk backend device, it uses UNIX'

introcudes -> introduces

> 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 <address@hidden>
> ---
>  .gitignore                              |   1 +
>  Makefile                                |   3 +
>  Makefile.objs                           |   1 +
>  contrib/vhost-user-blk/Makefile.objs    |   1 +
>  contrib/vhost-user-blk/vhost-user-blk.c | 543 
> ++++++++++++++++++++++++++++++++
>  5 files changed, 549 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 433f64f..704b222 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -54,6 +54,7 @@
>  /module_block.h
>  /scsi/qemu-pr-helper
>  /vhost-user-scsi
> +/vhost-user-blk
>  /fsdev/virtfs-proxy-helper
>  *.tmp
>  *.[1-9]
> diff --git a/Makefile b/Makefile
> index d86ecd2..f021fc8 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -331,6 +331,7 @@ dummy := $(call unnest-vars,, \
>                  ivshmem-server-obj-y \
>                  libvhost-user-obj-y \
>                  vhost-user-scsi-obj-y \
> +                vhost-user-blk-obj-y \
>                  qga-vss-dll-obj-y \
>                  block-obj-y \
>                  block-obj-m \
> @@ -562,6 +563,8 @@ ivshmem-server$(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..4649435
> --- /dev/null
> +++ b/contrib/vhost-user-blk/vhost-user-blk.c
> @@ -0,0 +1,543 @@
> +/*
> + * vhost-user-blk sample application
> + *
> + * Copyright (c) 2017 Intel Corporation. All rights reserved.
> + *
> + * Author:
> + *  Changpeng Liu <address@hidden>
> + *
> + * This work is based on the "vhost-user-scsi" sample and "virtio-blk" driver
> + * implemention by:

implemention -> implementation

> + *  Felipe Franciosi <address@hidden>
> + *  Anthony Liguori <address@hidden>
> + *
> + * 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  **/

let's use regular /* comment */ (I know vhost-user-scsi uses both
style for some reason)

> +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 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));

(there should be an optimization possible here, where you allocate
with a size > VuVirtqElement: this should avoid the need for second
allocation of VubReq)

> +    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");
> +    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_free(struct VubDev *vdev_blk)
> +{
> +    if (!vdev_blk) {
> +        return;
> +    }
> +
> +    g_main_loop_unref(vdev_blk->loop);
> +    if (vdev_blk->blk_fd >= 0) {
> +        close(vdev_blk->blk_fd);
> +    }
> +    g_free(vdev_blk);
> +}
> +
> +static uint32_t
> +vub_get_blocksize(int fd)
> +{
> +    uint32_t blocksize = 512;
> +
> +    #if defined(__linux__) && defined(BLKSSZGET)

Weird indentation, please keep preprocessor lines at first column.

> +    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 VubDev *
> +vub_new(char *blk_file)
> +{
> +    VubDev *vdev_blk;
> +
> +    vdev_blk = g_new0(VubDev, 1);
> +    vdev_blk->loop = g_main_loop_new(NULL, FALSE);
> +    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 NULL;

You leak vdev_blk here.

> +    }
> +    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 vdev_blk;
> +}
> +
> +int main(int argc, char **argv)
> +{
> +    int opt;
> +    char *unix_socket = NULL;
> +    char *blk_file = NULL;
> +    int lsock = -1, csock = -1;
> +    VubDev *vdev_blk = NULL;
> +
> +    while ((opt = getopt(argc, argv, "b:s:h")) != -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 0;
> +        }
> +    }
> +
> +    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 = vub_new(blk_file);
> +    if (!vdev_blk) {
> +        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:
> +    vub_free(vdev_blk);
> +    if (csock >= 0) {
> +        close(csock);
> +    }
> +    if (lsock >= 0) {
> +        close(lsock);
> +    }
> +    g_free(unix_socket);
> +    g_free(blk_file);
> +
> +    return 0;
> +}
> --
> 1.9.3
>
>

thanks

-- 
Marc-André Lureau