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block/export: Abstract out the logic of virtio-blk I/O process
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Abstract the common logic of virtio-blk I/O process to a function
named virtio_blk_process_req(). It's needed for the following commit.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Message-Id: <20220523084611.91-4-xieyongji@bytedance.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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@YongjiXie @kevmw
YongjiXie authored and kevmw committed Jun 24, 2022
1 parent 8e7fd6f commit 5c36802
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Showing 5 changed files with 301 additions and 239 deletions.
2 changes: 2 additions & 0 deletions MAINTAINERS
View file
Expand Up @@ -3580,6 +3580,8 @@ M: Coiby Xu <Coiby.Xu@gmail.com>
S: Maintained
F: block/export/vhost-user-blk-server.c
F: block/export/vhost-user-blk-server.h
F: block/export/virtio-blk-handler.c
F: block/export/virtio-blk-handler.h
F: include/qemu/vhost-user-server.h
F: tests/qtest/libqos/vhost-user-blk.c
F: tests/qtest/libqos/vhost-user-blk.h
Expand Down
2 changes: 1 addition & 1 deletion block/export/meson.build
View file
@@ -1,7 +1,7 @@
blockdev_ss.add(files('export.c'))

if have_vhost_user_blk_server
blockdev_ss.add(files('vhost-user-blk-server.c'))
blockdev_ss.add(files('vhost-user-blk-server.c', 'virtio-blk-handler.c'))
endif

blockdev_ss.add(when: fuse, if_true: files('fuse.c'))
259 changes: 21 additions & 238 deletions block/export/vhost-user-blk-server.c
View file
Expand Up @@ -17,31 +17,15 @@
#include "vhost-user-blk-server.h"
#include "qapi/error.h"
#include "qom/object_interfaces.h"
#include "sysemu/block-backend.h"
#include "util/block-helpers.h"

/*
* Sector units are 512 bytes regardless of the
* virtio_blk_config->blk_size value.
*/
#define VIRTIO_BLK_SECTOR_BITS 9
#define VIRTIO_BLK_SECTOR_SIZE (1ull << VIRTIO_BLK_SECTOR_BITS)
#include "virtio-blk-handler.h"

enum {
VHOST_USER_BLK_NUM_QUEUES_DEFAULT = 1,
VHOST_USER_BLK_MAX_DISCARD_SECTORS = 32768,
VHOST_USER_BLK_MAX_WRITE_ZEROES_SECTORS = 32768,
};
struct virtio_blk_inhdr {
unsigned char status;
};

typedef struct VuBlkReq {
VuVirtqElement elem;
int64_t sector_num;
size_t size;
struct virtio_blk_inhdr *in;
struct virtio_blk_outhdr out;
VuServer *server;
struct VuVirtq *vq;
} VuBlkReq;
Expand All @@ -50,247 +34,44 @@ typedef struct VuBlkReq {
typedef struct {
BlockExport export;
VuServer vu_server;
uint32_t blk_size;
VirtioBlkHandler handler;
QIOChannelSocket *sioc;
struct virtio_blk_config blkcfg;
bool writable;
} VuBlkExport;

static void vu_blk_req_complete(VuBlkReq *req)
static void vu_blk_req_complete(VuBlkReq *req, size_t in_len)
{
VuDev *vu_dev = &req->server->vu_dev;

vu_queue_push(vu_dev, req->vq, &req->elem, req->size);
vu_queue_push(vu_dev, req->vq, &req->elem, in_len);
vu_queue_notify(vu_dev, req->vq);

free(req);
}

static bool vu_blk_sect_range_ok(VuBlkExport *vexp, uint64_t sector,
size_t size)
{
uint64_t nb_sectors;
uint64_t total_sectors;

if (size % VIRTIO_BLK_SECTOR_SIZE) {
return false;
}

nb_sectors = size >> VIRTIO_BLK_SECTOR_BITS;

QEMU_BUILD_BUG_ON(BDRV_SECTOR_SIZE != VIRTIO_BLK_SECTOR_SIZE);
if (nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
return false;
}
if ((sector << VIRTIO_BLK_SECTOR_BITS) % vexp->blk_size) {
return false;
}
blk_get_geometry(vexp->export.blk, &total_sectors);
if (sector > total_sectors || nb_sectors > total_sectors - sector) {
return false;
}
return true;
}

static int coroutine_fn
vu_blk_discard_write_zeroes(VuBlkExport *vexp, struct iovec *iov,
uint32_t iovcnt, uint32_t type)
{
BlockBackend *blk = vexp->export.blk;
struct virtio_blk_discard_write_zeroes desc;
ssize_t size;
uint64_t sector;
uint32_t num_sectors;
uint32_t max_sectors;
uint32_t flags;
int bytes;

/* Only one desc is currently supported */
if (unlikely(iov_size(iov, iovcnt) > sizeof(desc))) {
return VIRTIO_BLK_S_UNSUPP;
}

size = iov_to_buf(iov, iovcnt, 0, &desc, sizeof(desc));
if (unlikely(size != sizeof(desc))) {
error_report("Invalid size %zd, expected %zu", size, sizeof(desc));
return VIRTIO_BLK_S_IOERR;
}

sector = le64_to_cpu(desc.sector);
num_sectors = le32_to_cpu(desc.num_sectors);
flags = le32_to_cpu(desc.flags);
max_sectors = (type == VIRTIO_BLK_T_WRITE_ZEROES) ?
VHOST_USER_BLK_MAX_WRITE_ZEROES_SECTORS :
VHOST_USER_BLK_MAX_DISCARD_SECTORS;

/* This check ensures that 'bytes' fits in an int */
if (unlikely(num_sectors > max_sectors)) {
return VIRTIO_BLK_S_IOERR;
}

bytes = num_sectors << VIRTIO_BLK_SECTOR_BITS;

if (unlikely(!vu_blk_sect_range_ok(vexp, sector, bytes))) {
return VIRTIO_BLK_S_IOERR;
}

/*
* The device MUST set the status byte to VIRTIO_BLK_S_UNSUPP for discard
* and write zeroes commands if any unknown flag is set.
*/
if (unlikely(flags & ~VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP)) {
return VIRTIO_BLK_S_UNSUPP;
}

if (type == VIRTIO_BLK_T_WRITE_ZEROES) {
int blk_flags = 0;

if (flags & VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP) {
blk_flags |= BDRV_REQ_MAY_UNMAP;
}

if (blk_co_pwrite_zeroes(blk, sector << VIRTIO_BLK_SECTOR_BITS,
bytes, blk_flags) == 0) {
return VIRTIO_BLK_S_OK;
}
} else if (type == VIRTIO_BLK_T_DISCARD) {
/*
* The device MUST set the status byte to VIRTIO_BLK_S_UNSUPP for
* discard commands if the unmap flag is set.
*/
if (unlikely(flags & VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP)) {
return VIRTIO_BLK_S_UNSUPP;
}

if (blk_co_pdiscard(blk, sector << VIRTIO_BLK_SECTOR_BITS,
bytes) == 0) {
return VIRTIO_BLK_S_OK;
}
}

return VIRTIO_BLK_S_IOERR;
}

/* Called with server refcount increased, must decrease before returning */
static void coroutine_fn vu_blk_virtio_process_req(void *opaque)
{
VuBlkReq *req = opaque;
VuServer *server = req->server;
VuVirtqElement *elem = &req->elem;
uint32_t type;

VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server);
BlockBackend *blk = vexp->export.blk;

VirtioBlkHandler *handler = &vexp->handler;
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) {
error_report("virtio-blk request missing headers");
goto err;
}

if (unlikely(iov_to_buf(out_iov, out_num, 0, &req->out,
sizeof(req->out)) != sizeof(req->out))) {
error_report("virtio-blk request outhdr too short");
goto err;
}

iov_discard_front(&out_iov, &out_num, sizeof(req->out));

if (in_iov[in_num - 1].iov_len < sizeof(struct virtio_blk_inhdr)) {
error_report("virtio-blk request inhdr too short");
goto err;
}

req->size = iov_size(in_iov, in_num);
/* 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 = le32_to_cpu(req->out.type);
switch (type & ~VIRTIO_BLK_T_BARRIER) {
case VIRTIO_BLK_T_IN:
case VIRTIO_BLK_T_OUT: {
QEMUIOVector qiov;
int64_t offset;
ssize_t ret = 0;
bool is_write = type & VIRTIO_BLK_T_OUT;
req->sector_num = le64_to_cpu(req->out.sector);

if (is_write && !vexp->writable) {
req->in->status = VIRTIO_BLK_S_IOERR;
break;
}

if (is_write) {
qemu_iovec_init_external(&qiov, out_iov, out_num);
} else {
qemu_iovec_init_external(&qiov, in_iov, in_num);
}

if (unlikely(!vu_blk_sect_range_ok(vexp,
req->sector_num,
qiov.size))) {
req->in->status = VIRTIO_BLK_S_IOERR;
break;
}

offset = req->sector_num << VIRTIO_BLK_SECTOR_BITS;

if (is_write) {
ret = blk_co_pwritev(blk, offset, qiov.size, &qiov, 0);
} else {
ret = blk_co_preadv(blk, offset, qiov.size, &qiov, 0);
}
if (ret >= 0) {
req->in->status = VIRTIO_BLK_S_OK;
} else {
req->in->status = VIRTIO_BLK_S_IOERR;
}
break;
}
case VIRTIO_BLK_T_FLUSH:
if (blk_co_flush(blk) == 0) {
req->in->status = VIRTIO_BLK_S_OK;
} else {
req->in->status = VIRTIO_BLK_S_IOERR;
}
break;
case VIRTIO_BLK_T_GET_ID: {
size_t size = MIN(iov_size(&elem->in_sg[0], in_num),
VIRTIO_BLK_ID_BYTES);
snprintf(elem->in_sg[0].iov_base, size, "%s", "vhost_user_blk");
req->in->status = VIRTIO_BLK_S_OK;
break;
int in_len;

in_len = virtio_blk_process_req(handler, in_iov, out_iov,
in_num, out_num);
if (in_len < 0) {
free(req);
vhost_user_server_unref(server);
return;
}
case VIRTIO_BLK_T_DISCARD:
case VIRTIO_BLK_T_WRITE_ZEROES: {
if (!vexp->writable) {
req->in->status = VIRTIO_BLK_S_IOERR;
break;
}

req->in->status = vu_blk_discard_write_zeroes(vexp, out_iov, out_num,
type);
break;
}
default:
req->in->status = VIRTIO_BLK_S_UNSUPP;
break;
}

vu_blk_req_complete(req);
vhost_user_server_unref(server);
return;

err:
free(req);
vu_blk_req_complete(req, in_len);
vhost_user_server_unref(server);
}

Expand Down Expand Up @@ -347,7 +128,7 @@ static uint64_t vu_blk_get_features(VuDev *dev)
1ull << VIRTIO_RING_F_EVENT_IDX |
1ull << VHOST_USER_F_PROTOCOL_FEATURES;

if (!vexp->writable) {
if (!vexp->handler.writable) {
features |= 1ull << VIRTIO_BLK_F_RO;
}

Expand Down Expand Up @@ -454,12 +235,12 @@ vu_blk_initialize_config(BlockDriverState *bs,
config->opt_io_size = cpu_to_le32(1);
config->num_queues = cpu_to_le16(num_queues);
config->max_discard_sectors =
cpu_to_le32(VHOST_USER_BLK_MAX_DISCARD_SECTORS);
cpu_to_le32(VIRTIO_BLK_MAX_DISCARD_SECTORS);
config->max_discard_seg = cpu_to_le32(1);
config->discard_sector_alignment =
cpu_to_le32(blk_size >> VIRTIO_BLK_SECTOR_BITS);
config->max_write_zeroes_sectors
= cpu_to_le32(VHOST_USER_BLK_MAX_WRITE_ZEROES_SECTORS);
= cpu_to_le32(VIRTIO_BLK_MAX_WRITE_ZEROES_SECTORS);
config->max_write_zeroes_seg = cpu_to_le32(1);
}

Expand All @@ -479,7 +260,6 @@ static int vu_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
uint64_t logical_block_size;
uint16_t num_queues = VHOST_USER_BLK_NUM_QUEUES_DEFAULT;

vexp->writable = opts->writable;
vexp->blkcfg.wce = 0;

if (vu_opts->has_logical_block_size) {
Expand All @@ -493,7 +273,6 @@ static int vu_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
error_propagate(errp, local_err);
return -EINVAL;
}
vexp->blk_size = logical_block_size;

if (vu_opts->has_num_queues) {
num_queues = vu_opts->num_queues;
Expand All @@ -502,6 +281,10 @@ static int vu_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
error_setg(errp, "num-queues must be greater than 0");
return -EINVAL;
}
vexp->handler.blk = exp->blk;
vexp->handler.serial = "vhost_user_blk";
vexp->handler.logical_block_size = logical_block_size;
vexp->handler.writable = opts->writable;

vu_blk_initialize_config(blk_bs(exp->blk), &vexp->blkcfg,
logical_block_size, num_queues);
Expand Down

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