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virtio_dev.c
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virtio_dev.c
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/*-
* BSD LICENSE
*
* Copyright (c) Cloudbyte Corporation.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Cloudbyte Corporation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <poll.h>
#include <sys/eventfd.h>
// DPDK include
#include <rte_ring.h>
// includes coming from SPDK
#include "virtio_scsi.h"
#include "scsi_spec.h"
#include "endian.h"
// Our own includes
#include "virtio_dev.h"
#include "virtio_task.h"
#include "vhost_client.h"
#include "vring_poller.h"
#include "vring.h"
#include "shm.h"
#include "common.h"
// output queue size for async operations
#define OUTRING_SIZE 4096
// payload size for SCSI inquiry command
#define VIRTIO_SCAN_PAYLOAD_SIZE 256
// hardcoded target ID and LUN
#define TARGET_ID 1
// hardcoded because we don't scan all possible LUN IDs
#define LUN_ID 0
/*
* Each type of queue has its own vring
* but we use only the request queue.
*/
enum virtio_queue_type {
VIRTIO_SCSI_CONTROLQ = 0,
VIRTIO_SCSI_EVENTQ,
VIRTIO_SCSI_REQUESTQ,
VIRTIO_SCSI_QCOUNT,
};
/*
* Virtio device state.
*/
struct virtio_dev {
vhost_client_t *client;
vring_t *vring[VIRTIO_SCSI_QCOUNT];
vring_poller_t *poller;
int block_size;
size_t num_blocks;
size_t cap;
// async IOs
struct rte_ring *outring;
int outfd;
int event_high_wm; // high-water mark for generating event
};
int
libvirtio_dev_init(int mem_mb, int core_mask)
{
return (init_shared_mem(mem_mb, core_mask));
}
static int
send_inquiry(struct virtio_dev *dev)
{
virtio_task_t *task;
struct virtio_scsi_cmd_req *req;
struct virtio_scsi_cmd_resp *resp;
struct spdk_scsi_cdb_inquiry *cdb;
struct spdk_scsi_cdb_inquiry_data *inquiry_data;
int rc;
task = virtio_task_create(3);
if (task == NULL)
return (-1);
req = virtio_task_alloc_buf(task, sizeof (*req), false, true);
resp = virtio_task_alloc_buf(task, sizeof (*resp), true, true);
inquiry_data = virtio_task_alloc_buf(task, VIRTIO_SCAN_PAYLOAD_SIZE, true, false);
req->lun[0] = TARGET_ID;
req->lun[1] = LUN_ID;
cdb = (struct spdk_scsi_cdb_inquiry *)req->cdb;
cdb->opcode = SPDK_SPC_INQUIRY;
cdb->evpd = 0;
cdb->page_code = 0;
to_be16(cdb->alloc_len, VIRTIO_SCAN_PAYLOAD_SIZE);
//cdb->control =
rc = vring_submit_task_sync(dev->poller, task);
if (rc != 0) {
virtio_task_destroy(task);
return (-1);
}
if (resp->response != VIRTIO_SCSI_S_OK ||
resp->status != SPDK_SCSI_STATUS_GOOD) {
virtio_task_destroy(task);
return (-1);
}
if (inquiry_data->peripheral_device_type != SPDK_SPC_PERIPHERAL_DEVICE_TYPE_DISK ||
inquiry_data->peripheral_qualifier != SPDK_SPC_PERIPHERAL_QUALIFIER_CONNECTED) {
fprintf(stderr, "Unsupported peripheral device type 0x%02x (qualifier 0x%02x)\n",
inquiry_data->peripheral_device_type,
inquiry_data->peripheral_qualifier);
return (-1);
}
inquiry_data->product_id[sizeof (inquiry_data->product_id) - 1] = '\0';
inquiry_data->t10_vendor_id[sizeof (inquiry_data->t10_vendor_id) - 1] = '\0';
debug("Device name: %s, Vendor: %s\n",
inquiry_data->product_id, inquiry_data->t10_vendor_id);
return (0);
}
static int
send_test_unit_ready(struct virtio_dev *dev)
{
virtio_task_t *task;
struct virtio_scsi_cmd_req *req;
struct virtio_scsi_cmd_resp *resp;
int rc;
task = virtio_task_create(2);
if (task == NULL)
return (-1);
req = virtio_task_alloc_buf(task, sizeof (*req), false, true);
resp = virtio_task_alloc_buf(task, sizeof (*resp), true, true);
req->lun[0] = TARGET_ID;
req->lun[1] = LUN_ID;
req->cdb[0] = SPDK_SPC_TEST_UNIT_READY;
rc = vring_submit_task_sync(dev->poller, task);
if (rc != 0) {
virtio_task_destroy(task);
return (-1);
}
if (resp->response != VIRTIO_SCSI_S_OK ||
resp->status != SPDK_SCSI_STATUS_GOOD) {
virtio_task_destroy(task);
return (-1);
}
return (0);
}
static int
send_read_cap(struct virtio_dev *dev)
{
virtio_task_t *task;
struct virtio_scsi_cmd_req *req;
struct virtio_scsi_cmd_resp *resp;
uint8_t *payload;
int rc;
task = virtio_task_create(3);
if (task == NULL)
return (-1);
req = virtio_task_alloc_buf(task, sizeof (*req), false, true);
resp = virtio_task_alloc_buf(task, sizeof (*resp), true, true);
payload = virtio_task_alloc_buf(task, 32, true, true);
req->lun[0] = TARGET_ID;
req->lun[1] = LUN_ID;
req->cdb[0] = SPDK_SPC_SERVICE_ACTION_IN_16;
req->cdb[1] = SPDK_SBC_SAI_READ_CAPACITY_16;
to_be32(&req->cdb[10], 32);
rc = vring_submit_task_sync(dev->poller, task);
if (rc != 0) {
virtio_task_destroy(task);
return (-1);
}
if (resp->response != VIRTIO_SCSI_S_OK ||
resp->status != SPDK_SCSI_STATUS_GOOD) {
virtio_task_destroy(task);
return (-1);
}
dev->num_blocks = from_be64(payload) + 1;
dev->block_size = from_be32(payload + 8);
dev->cap = dev->block_size * dev->num_blocks;
debug("Block size %d. Number of blocks %lu => Capacity %lu bytes.\n",
dev->block_size, dev->num_blocks, dev->cap);
return (0);
}
dev_handle_t
open_virtio_dev(const char *sock)
{
struct virtio_dev *dev;
dev = calloc(1, sizeof (*dev));
if (dev == NULL)
return (NULL);
dev->client = new_vhost_client(sock);
if (dev->client == NULL)
goto error;
for (int i = 0; i < VIRTIO_SCSI_QCOUNT; i++) {
dev->vring[i] = vring_create();
if (dev->vring[i] == NULL)
goto error;
}
if (init_vhost_client(dev->client) != 0)
goto error;
/* push vring info to the server */
for (int i = 0; i < VIRTIO_SCSI_QCOUNT; i++) {
if (set_vhost_vring(dev->client, dev->vring[i], i) != 0)
goto error;
}
/* output queue for async requests */
dev->outring = rte_ring_create("output_request_ring", OUTRING_SIZE,
SOCKET_ID_ANY, 0);
if (dev->outring == NULL)
goto error;
dev->event_high_wm = 0;
/* notifications when new item arrives to output ring go here */
dev->outfd = eventfd(0, EFD_NONBLOCK);
if (dev->outfd < 0) {
goto error;
}
// TODO: we ignore all other rings except request ring
dev->poller = vring_poller_create(dev->vring[VIRTIO_SCSI_REQUESTQ]);
if (dev->poller == NULL)
goto error;
if (vring_poller_start(dev->poller) != 0)
goto error;
if (send_inquiry(dev) != 0)
goto error;
if (send_test_unit_ready(dev) != 0)
goto error;
if (send_read_cap(dev) != 0)
goto error;
return (dev);
error:
if (dev->poller != NULL)
vring_poller_destroy(dev->poller);
if (dev->client != NULL)
end_vhost_client(dev->client);
for (int i = 0; i < VIRTIO_SCSI_QCOUNT; i++) {
if (dev->vring[i] != NULL)
vring_destroy(dev->vring[i]);
}
if (dev->outring != NULL)
rte_ring_free(dev->outring);
if (dev->outfd > 0)
close(dev->outfd);
free(dev);
return (NULL);
}
void
close_virtio_dev(dev_handle_t hdl)
{
struct virtio_dev *dev = hdl;
vring_poller_destroy(dev->poller);
end_vhost_client(dev->client);
for (int i = 0; i < VIRTIO_SCSI_QCOUNT; i++)
vring_destroy(dev->vring[i]);
close(dev->outfd);
rte_ring_free(dev->outring);
free(dev);
}
size_t
virtio_dev_block_size(dev_handle_t hdl)
{
struct virtio_dev *dev = hdl;
return (dev->block_size);
}
size_t
virtio_dev_blocks_num(dev_handle_t hdl)
{
struct virtio_dev *dev = hdl;
return (dev->num_blocks);
}
static void
create_rw_cdb(struct virtio_dev *dev, void *buf,
size_t offset_blocks, size_t num_blocks, int is_write)
{
struct virtio_scsi_cmd_req *req = buf;
req->lun[0] = TARGET_ID;
req->lun[1] = LUN_ID;
if (dev->num_blocks > (1ULL << 32)) {
req->cdb[0] = is_write ? SPDK_SBC_WRITE_16 : SPDK_SBC_READ_16;
to_be64(&req->cdb[2], offset_blocks);
to_be32(&req->cdb[10], num_blocks);
} else {
req->cdb[0] = is_write ? SPDK_SBC_WRITE_10 : SPDK_SBC_READ_10;
to_be32(&req->cdb[2], offset_blocks);
to_be16(&req->cdb[7], num_blocks);
}
}
/*
* Read buffer schema:
*
* -----------------------
* virtio_scsi_cmd_req (R)
* -----------------------
* virtio_scsi_cmd_resp(W)
* -----------------------
* data ... (W)
* -----------------------
*/
static int
blk_read_virtio_dev(struct virtio_dev *dev, void *buf, size_t blk_offset,
size_t nblk)
{
virtio_task_t *task;
struct virtio_scsi_cmd_req *req;
struct virtio_scsi_cmd_resp *resp;
int rc;
task = virtio_task_create(3);
if (task == NULL)
return (-1);
req = virtio_task_alloc_buf(task, sizeof (*req), false, true);
resp = virtio_task_alloc_buf(task, sizeof (*resp), true, true);
virtio_task_add_buf(task, buf, nblk * dev->block_size, true);
if (req == NULL || resp == NULL) {
virtio_task_destroy(task);
return (-1);
}
create_rw_cdb(dev, req, blk_offset, nblk, 0);
rc = vring_submit_task_sync(dev->poller, task);
if (rc != 0) {
virtio_task_destroy(task);
return (-1);
}
if (resp->response != VIRTIO_SCSI_S_OK ||
resp->status != SPDK_SCSI_STATUS_GOOD) {
virtio_task_destroy(task);
return (-1);
}
rc = task->used_bytes - sizeof (*resp);
assert(rc >= 0);
virtio_task_destroy(task);
return (rc);
}
/*
* Write buffer schema:
*
* -----------------------
* virtio_scsi_cmd_req (R)
* -----------------------
* data ... (R)
* -----------------------
* virtio_scsi_cmd_resp(W)
* -----------------------
*/
static int
blk_write_virtio_dev(struct virtio_dev *dev, void *buf, size_t blk_offset,
size_t nblk)
{
virtio_task_t *task;
struct virtio_scsi_cmd_req *req;
struct virtio_scsi_cmd_resp *resp;
int nbytes = nblk * dev->block_size;
task = virtio_task_create(3);
if (task == NULL)
return (-1);
req = virtio_task_alloc_buf(task, sizeof (*req), false, true);
virtio_task_add_buf(task, buf, nbytes, false);
resp = virtio_task_alloc_buf(task, sizeof (*resp), true, true);
if (req == NULL || resp == NULL) {
virtio_task_destroy(task);
return (-1);
}
create_rw_cdb(dev, req, blk_offset, nblk, 1);
if (vring_submit_task_sync(dev->poller, task) != 0) {
virtio_task_destroy(task);
return (-1);
}
if (resp->response != VIRTIO_SCSI_S_OK || resp->status != SPDK_SCSI_STATUS_GOOD) {
virtio_task_destroy(task);
return (-1);
}
virtio_task_destroy(task);
return (nbytes);
}
/*
* Read range of bytes from a block.
*/
static int
read_partial_block(struct virtio_dev *dev, size_t blk_num,
size_t off_start, void *data, size_t nbytes)
{
char *blk_buf = alloc_shared_buf(dev->block_size, dev->block_size);
if (off_start + nbytes > dev->block_size)
nbytes = dev->block_size - off_start;
if (blk_read_virtio_dev(dev, blk_buf, blk_num, 1) != dev->block_size) {
free_shared_buf(blk_buf);
return (-1);
}
memcpy(data, blk_buf + off_start, nbytes);
free_shared_buf(blk_buf);
return (nbytes);
}
/*
* Convenient but also slow function for reading bytes from device
* synchronously without data copy. Provided buffer must be
* allocated from huge pages.
*/
int
read_virtio_dev(struct virtio_dev *dev, void *buf, size_t offset,
size_t nbytes)
{
size_t nblk;
size_t blk_offset;
size_t read_bytes = 0;
int resid_offset;
int ret;
if (offset > dev->cap)
return (-1);
if (nbytes == 0)
return (0);
if (offset + nbytes > dev->cap)
nbytes = dev->cap - offset;
blk_offset = offset / dev->block_size;
resid_offset = offset % dev->block_size;
if (resid_offset != 0) {
ret = read_partial_block(dev, blk_offset, resid_offset, buf, nbytes);
if (ret < 0)
return (-1);
if (ret < dev->block_size - resid_offset)
return (ret);
read_bytes += ret;
blk_offset++;
}
nblk = (nbytes - read_bytes) / dev->block_size;
if (nblk > 0) {
ret = blk_read_virtio_dev(dev, (char *)buf + read_bytes, blk_offset, nblk);
if (ret < 0)
return (read_bytes);
if (ret < nblk * dev->block_size)
return (read_bytes + ret);
read_bytes += ret;
blk_offset += nblk;
}
resid_offset = (nbytes - read_bytes) % dev->block_size;
if (resid_offset != 0) {
ret = read_partial_block(dev, blk_offset, 0, (char *)buf + read_bytes, resid_offset);
if (ret < 0)
return (-1);
read_bytes += ret;
}
return (read_bytes);
}
/*
* Write a block which is not fully overwritten, hence it needs to be
* read from storage, modified and written back.
*/
static int
write_partial_block(struct virtio_dev *dev, size_t blk_num,
size_t off_start, void *data, size_t nbytes)
{
char *blk_buf = alloc_shared_buf(dev->block_size, dev->block_size);
int ret;
if (off_start + nbytes > dev->block_size)
nbytes = dev->block_size - off_start;
if (blk_read_virtio_dev(dev, blk_buf, blk_num, 1) != dev->block_size) {
free_shared_buf(blk_buf);
return (-1);
}
memcpy(blk_buf + off_start, data, nbytes);
ret = blk_write_virtio_dev(dev, blk_buf, blk_num, 1);
free_shared_buf(blk_buf);
return (ret - dev->block_size + nbytes);
}
/*
* Convenient but also slow function for writing bytes to device
* synchronously without data copy. Provided buffer must be
* allocated from huge pages.
*/
int
write_virtio_dev(struct virtio_dev *dev, void *buf, size_t offset,
size_t nbytes)
{
size_t nblk;
size_t blk_offset;
size_t written_bytes = 0;
int resid_offset;
int ret;
if (offset > dev->cap)
return (-1);
if (nbytes == 0)
return (0);
if (offset + nbytes > dev->cap)
nbytes = dev->cap - offset;
blk_offset = offset / dev->block_size;
resid_offset = offset % dev->block_size;
if (resid_offset != 0) {
ret = write_partial_block(dev, blk_offset, resid_offset, buf, nbytes);
if (ret < 0)
return (-1);
if (ret < dev->block_size - resid_offset)
return (ret);
written_bytes += ret;
blk_offset++;
}
nblk = (nbytes - written_bytes) / dev->block_size;
if (nblk > 0) {
ret = blk_write_virtio_dev(dev, (char *)buf + written_bytes, blk_offset, nblk);
if (ret < 0)
return (written_bytes);
if (ret < nblk * dev->block_size)
return (written_bytes + ret);
written_bytes += ret;
blk_offset += nblk;
}
resid_offset = (nbytes - written_bytes) % dev->block_size;
if (resid_offset != 0) {
ret = write_partial_block(dev, blk_offset, 0, (char *)buf + written_bytes, resid_offset);
if (ret < 0)
return (-1);
written_bytes += ret;
}
return (written_bytes);
}
/***********************************************
* Async read/write.
***********************************************/
static void
push_to_outring(struct virtio_dev *dev, async_io_desc_t *io_desc)
{
int rc;
rc = rte_ring_sp_enqueue(dev->outring, io_desc);
// XXX implement throttling
assert(rc == 0);
if (dev->event_high_wm > 0 &&
dev->event_high_wm <= rte_ring_count(dev->outring)) {
uint64_t kick_it = 1;
rc = write(dev->outfd, &kick_it, sizeof(kick_it));
assert(rc == sizeof(kick_it));
fsync(dev->outfd);
}
}
/*
* Async read blocks callback.
*/
static void
blk_read_done(struct virtio_task *task, void *arg)
{
async_io_desc_t *io_desc = arg;
struct virtio_dev *dev = io_desc->reserved;
struct virtio_scsi_cmd_resp *resp = virtio_task_get_buf(task, 1);
size_t nbytes = 0;
size_t used_bytes = task->used_bytes - sizeof (*resp);
io_desc->retval = -1;
if (resp->response == VIRTIO_SCSI_S_OK &&
resp->status == SPDK_SCSI_STATUS_GOOD) {
for (int i = 2; i < task->count; i++) {
virtio_buffer_t *vbuf = &task->vbufs[i];
size_t delta = vbuf->offset_to - vbuf->offset_from;
if (nbytes + delta > used_bytes)
delta = used_bytes - nbytes;
if (vbuf->copy) {
memcpy((char *)io_desc->buf + nbytes,
vbuf->buf + vbuf->offset_from, delta);
}
nbytes += delta;
if (nbytes >= used_bytes)
break;
}
assert(nbytes <= used_bytes);
io_desc->retval = nbytes;
}
push_to_outring(dev, io_desc);
virtio_task_destroy(task);
}
/*
* Async zero-copy read operation. Provided buffer must be allocated from
* huge pages.
*
* Read buffer schema:
*
* -----------------------
* virtio_scsi_cmd_req (R)
* -----------------------
* virtio_scsi_cmd_resp(W)
* -----------------------
* data ... (W)
* -----------------------
*/
static int
read_virtio_dev_async(struct virtio_dev *dev, async_io_desc_t *io_desc)
{
virtio_task_t *task;
struct virtio_scsi_cmd_req *req;
struct virtio_scsi_cmd_resp *resp;
char *buf = io_desc->buf;
size_t offset = io_desc->offset;
size_t nbytes = io_desc->nbytes;
size_t nblk = 0;
size_t temp;
size_t blk_offset;
size_t read_bytes = 0;
int resid_offset;
int rc;
if (offset > dev->cap)
return (-1);
if (nbytes == 0)
return (0);
if (offset + nbytes > dev->cap)
nbytes = dev->cap - offset;
io_desc->reserved = dev;
task = virtio_task_create(5);
if (task == NULL)
return (-1);
req = virtio_task_alloc_buf(task, sizeof (*req), false, true);
resp = virtio_task_alloc_buf(task, sizeof (*resp), true, true);
if (req == NULL || resp == NULL) {
virtio_task_destroy(task);
return (-1);
}
blk_offset = offset / dev->block_size;
resid_offset = offset % dev->block_size;
// partial read of the first block
if (resid_offset != 0) {
nblk++;
if (resid_offset + nbytes <= dev->block_size)
read_bytes = nbytes;
else
read_bytes = (dev->block_size - resid_offset);
if (virtio_task_alloc_buf_part(task, dev->block_size, true, false,
resid_offset, resid_offset + read_bytes) == NULL) {
virtio_task_destroy(task);
return (-1);
}
}
// middle part which is block size aligned
if ((nbytes - read_bytes) / dev->block_size > 0) {
temp = (nbytes - read_bytes) / dev->block_size;
virtio_task_add_buf(task, buf + read_bytes, temp * dev->block_size, true);
nblk += temp;
read_bytes += temp * dev->block_size;
}
// partial read of the last block
resid_offset = (nbytes - read_bytes) % dev->block_size;
if (read_bytes < nbytes && resid_offset != 0) {
nblk++;
if (virtio_task_alloc_buf_part(task, dev->block_size, true, false,
0, resid_offset) == NULL) {
virtio_task_destroy(task);
return (-1);
}
}
create_rw_cdb(dev, req, blk_offset, nblk, false);
rc = vring_submit_task(dev->poller, task, blk_read_done, io_desc);
if (rc != 0) {
virtio_task_destroy(task);
return (-1);
}
return (0);
}
/*
* Callback called after final partial block has been written.
*/
static void
blk_write_last_block_done(struct virtio_task *task, void *arg)
{
async_io_desc_t *io_desc = arg;
struct virtio_dev *dev = io_desc->reserved;
struct virtio_scsi_cmd_resp *resp = virtio_task_get_buf(task, 2);
virtio_buffer_t *vbuf;
assert(task->count == 3);
if (resp->response == VIRTIO_SCSI_S_OK &&
resp->status == SPDK_SCSI_STATUS_GOOD) {
vbuf = &task->vbufs[1];
if (io_desc->retval < 0)
io_desc->retval = vbuf->offset_to - vbuf->offset_from;
else
io_desc->retval += vbuf->offset_to - vbuf->offset_from;
}
push_to_outring(dev, io_desc);
virtio_task_destroy(task);
}
/*
* Callback for reading last block which should be partially overwritten.
*/
static void
blk_read_last_block_done(struct virtio_task *task, void *arg)
{
struct virtio_task *new_task = NULL;
async_io_desc_t *io_desc = arg;
struct virtio_dev *dev = io_desc->reserved;
struct virtio_scsi_cmd_req *req;
struct virtio_scsi_cmd_resp *resp = virtio_task_get_buf(task, 1);
virtio_buffer_t *vbuf;
size_t delta;
size_t blk_offset;
char *buf;
int rc;
assert(task->count == 3);
if (resp->response != VIRTIO_SCSI_S_OK ||
resp->status != SPDK_SCSI_STATUS_GOOD) {
goto write_done;
}
new_task = virtio_task_create(4);
if (new_task == NULL)
goto write_done;
req = virtio_task_alloc_buf(new_task, sizeof (*req), false, true);
if (req == NULL)
goto write_done;
// copy vbuf from original read task to new write task
// inefficient but we don't care that much about unaligned writes
vbuf = &task->vbufs[2];
buf = virtio_task_alloc_buf_part(new_task, dev->block_size, false, false,
vbuf->offset_from, vbuf->offset_to);
if (buf == NULL)
goto write_done;
delta = vbuf->offset_to - vbuf->offset_from;
memcpy(buf, vbuf->buf, vbuf->size);
memcpy(buf, (char *)io_desc->buf + io_desc->nbytes - delta, delta);
blk_offset = (io_desc->offset + io_desc->nbytes) / dev->block_size;
create_rw_cdb(dev, req, blk_offset, 1, true);
resp = virtio_task_alloc_buf(new_task, sizeof (*resp), true, true);
if (resp == NULL)
goto write_done;
rc = vring_submit_task(dev->poller, new_task, blk_write_last_block_done,
io_desc);
if (rc != 0)
goto write_done;
virtio_task_destroy(task);
return;
write_done:
push_to_outring(dev, io_desc);
virtio_task_destroy(task);
if (new_task != NULL)
virtio_task_destroy(new_task);
}
/*
* Callback called when optional first partial block and all following full
* blocks have been written.
*/
static void
blk_write_full_blocks_done(struct virtio_task *task, void *arg)
{
async_io_desc_t *io_desc = arg;
struct virtio_dev *dev = io_desc->reserved;
struct virtio_scsi_cmd_req *req;
struct virtio_scsi_cmd_resp *resp = virtio_task_get_buf(task, task->count - 1);
virtio_buffer_t *vbuf;
size_t nbytes = 0;
size_t offset;
size_t blk_offset;
int resid_offset;
int rc;
assert(task->count > 2);
if (resp->response != VIRTIO_SCSI_S_OK ||
resp->status != SPDK_SCSI_STATUS_GOOD) {
goto write_done;
}
// we have written the blocks, see how much it was
for (int i = 1; i < task->count - 1; i++) {
vbuf = &task->vbufs[i];
nbytes += vbuf->offset_to - vbuf->offset_from;
}
io_desc->retval = nbytes;
// if the write was block aligned at the end then we are done
if (nbytes == io_desc->nbytes)
goto write_done;
virtio_task_destroy(task);
// create task for reading remaining bytes in the last block
task = virtio_task_create(3);
if (task == NULL)
goto write_done;
req = virtio_task_alloc_buf(task, sizeof (*req), false, true);
resp = virtio_task_alloc_buf(task, sizeof (*resp), true, true);
if (req == NULL || resp == NULL)
goto write_done;
offset = io_desc->offset + io_desc->nbytes;
blk_offset = offset / dev->block_size;
resid_offset = offset % dev->block_size;
assert(resid_offset != 0);
create_rw_cdb(dev, req, blk_offset, 1, false);
if (virtio_task_alloc_buf_part(task, dev->block_size, true, false,
0, resid_offset) == NULL) {
goto write_done;
}
rc = vring_submit_task(dev->poller, task, blk_read_last_block_done, io_desc);
if (rc != 0)
goto write_done;
return;
write_done:
push_to_outring(dev, io_desc);
if (task != NULL)
virtio_task_destroy(task);
}
/*
* First async step when writing a buffer which is not block-aligned.
*/
static void
blk_read_first_block_done(struct virtio_task *task, void *arg)
{
struct virtio_task *new_task = NULL;
async_io_desc_t *io_desc = arg;
struct virtio_dev *dev = io_desc->reserved;
struct virtio_scsi_cmd_req *req;
struct virtio_scsi_cmd_resp *resp = virtio_task_get_buf(task, 1);
virtio_buffer_t *vbuf;
size_t delta;
size_t blk_offset;
size_t nblk = 0;
char *buf;
int rc;
assert(task->count == 3);
if (resp->response != VIRTIO_SCSI_S_OK ||
resp->status != SPDK_SCSI_STATUS_GOOD) {
goto write_done;
}
new_task = virtio_task_create(4);
if (new_task == NULL)
goto write_done;
req = virtio_task_alloc_buf(new_task, sizeof (*req), false, true);
if (req == NULL)
goto write_done;
// copy vbuf from original read task to new write task
// inefficient but we don't care that much about unaligned writes
vbuf = &task->vbufs[2];
buf = virtio_task_alloc_buf_part(new_task, dev->block_size, false, false,
vbuf->offset_from, vbuf->offset_to);
if (buf == NULL)
goto write_done;
delta = vbuf->offset_to - vbuf->offset_from;
memcpy(buf, vbuf->buf, vbuf->size);
memcpy(buf + vbuf->offset_from, io_desc->buf, delta);
// if the read was more than just one partial block then add more
if (delta < io_desc->nbytes) {
nblk = (io_desc->nbytes - delta) / dev->block_size;
virtio_task_add_buf(new_task, (char *)io_desc->buf + delta,
nblk * dev->block_size, false);
}
nblk++; // for the first partial block
blk_offset = io_desc->offset / dev->block_size;
create_rw_cdb(dev, req, blk_offset, nblk, true);