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virtio-blk: use generic vectored I/O APIs (Christoph Hellwig) 

Use the generic bdrv_aio_readv/bdrv_aio_writev APIs instead of linearizing
buffers directly.  This enables using the future native preadv/pwritev
support.


Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6903 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
aliguori 2009-03-28 17:46:14 +00:00
parent 522584a57b
commit d28a1b6ec6
1 changed files with 17 additions and 71 deletions
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88
hw/virtio-blk.c
View File

@ -35,8 +35,7 @@ typedef struct VirtIOBlockReq
VirtQueueElement elem;
struct virtio_blk_inhdr *in;
struct virtio_blk_outhdr *out;
size_t size;
uint8_t *buffer;
QEMUIOVector qiov;
struct VirtIOBlockReq *next;
} VirtIOBlockReq;
@ -45,10 +44,9 @@ static void virtio_blk_req_complete(VirtIOBlockReq *req, int status)
VirtIOBlock *s = req->dev;
req->in->status = status;
virtqueue_push(s->vq, &req->elem, req->size + sizeof(*req->in));
virtqueue_push(s->vq, &req->elem, req->qiov.size + sizeof(*req->in));
virtio_notify(&s->vdev, s->vq);
qemu_free(req->buffer);
qemu_free(req);
}
@ -76,24 +74,7 @@ static void virtio_blk_rw_complete(void *opaque, int ret)
{
VirtIOBlockReq *req = opaque;
/* Copy read data to the guest */
if (!ret && !(req->out->type & VIRTIO_BLK_T_OUT)) {
size_t offset = 0;
int i;
for (i = 0; i < req->elem.in_num - 1; i++) {
size_t len;
/* Be pretty defensive wrt malicious guests */
len = MIN(req->elem.in_sg[i].iov_len,
req->size - offset);
memcpy(req->elem.in_sg[i].iov_base,
req->buffer + offset,
len);
offset += len;
}
} else if (ret && (req->out->type & VIRTIO_BLK_T_OUT)) {
if (ret && (req->out->type & VIRTIO_BLK_T_OUT)) {
if (virtio_blk_handle_write_error(req, -ret))
return;
}
@ -122,39 +103,16 @@ static VirtIOBlockReq *virtio_blk_get_request(VirtIOBlock *s)
return req;
}
static int virtio_blk_handle_write(VirtIOBlockReq *req)
static void virtio_blk_handle_write(VirtIOBlockReq *req)
{
if (!req->buffer) {
size_t offset = 0;
int i;
bdrv_aio_writev(req->dev->bs, req->out->sector, &req->qiov,
req->qiov.size / 512, virtio_blk_rw_complete, req);
}
for (i = 1; i < req->elem.out_num; i++)
req->size += req->elem.out_sg[i].iov_len;
req->buffer = qemu_memalign(512, req->size);
if (req->buffer == NULL) {
qemu_free(req);
return -1;
}
/* We copy the data from the SG list to avoid splitting up the request.
This helps performance a lot until we can pass full sg lists as AIO
operations */
for (i = 1; i < req->elem.out_num; i++) {
size_t len;
len = MIN(req->elem.out_sg[i].iov_len,
req->size - offset);
memcpy(req->buffer + offset,
req->elem.out_sg[i].iov_base,
len);
offset += len;
}
}
bdrv_aio_write(req->dev->bs, req->out->sector, req->buffer, req->size / 512,
virtio_blk_rw_complete, req);
return 0;
static void virtio_blk_handle_read(VirtIOBlockReq *req)
{
bdrv_aio_readv(req->dev->bs, req->out->sector, &req->qiov,
req->qiov.size / 512, virtio_blk_rw_complete, req);
}
static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
@ -163,8 +121,6 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
VirtIOBlockReq *req;
while ((req = virtio_blk_get_request(s))) {
int i;
if (req->elem.out_num < 1 || req->elem.in_num < 1) {
fprintf(stderr, "virtio-blk missing headers\n");
exit(1);
@ -187,23 +143,13 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
virtio_notify(vdev, vq);
qemu_free(req);
} else if (req->out->type & VIRTIO_BLK_T_OUT) {
if (virtio_blk_handle_write(req) < 0)
break;
qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],
req->elem.out_num - 1);
virtio_blk_handle_write(req);
} else {
for (i = 0; i < req->elem.in_num - 1; i++)
req->size += req->elem.in_sg[i].iov_len;
req->buffer = qemu_memalign(512, req->size);
if (req->buffer == NULL) {
qemu_free(req);
break;
}
bdrv_aio_read(s->bs, req->out->sector,
req->buffer,
req->size / 512,
virtio_blk_rw_complete,
req);
qemu_iovec_init_external(&req->qiov, &req->elem.in_sg[0],
req->elem.in_num - 1);
virtio_blk_handle_read(req);
}
}
/*