On Sat, 16 Apr 2011, Sasha Levin wrote:
Add optional support for scatter-gather to disk_image.
Formats that can't take advantage of scatter-gather fallback to simple IO.
Cool!
+static size_t raw_image__read_sector_sg(struct disk_image *self, uint64_t sector, const struct iovec *iov, int iovcount)
+{
+ uint64_t offset = sector << SECTOR_SHIFT;
+ size_t ret = -1;
+
+ ret = preadv(self->fd, iov, iovcount, offset);
+
+ return ret;
Please just do
return preadv(...);
Also, I guess you need preadv_in_full() similar to read_in_full() that
handles EINTR and EAGAIN.
+}
+
+static size_t raw_image__write_sector_sg(struct disk_image *self, uint64_t sector, const struct iovec *iov, int iovcount)
+{
+ uint64_t offset = sector << SECTOR_SHIFT;
+ size_t ret = -1;
+
+ ret = pwritev(self->fd, iov, iovcount, offset);
+
+ return ret;
Same comments apply here as well.
@@ -115,50 +115,23 @@ static bool virtio_blk_do_io_request(struct kvm *self, struct virt_queue *queue)
{
struct iovec iov[VIRTIO_BLK_QUEUE_SIZE];
struct virtio_blk_outhdr *req;
- uint32_t block_len, block_cnt;
+ size_t block_cnt = -1;
uint16_t out, in, head;
uint8_t *status;
- bool io_error;
- void *block;
- int err, i;
-
- io_error = false;
head = virt_queue__get_iov(queue, iov, &out, &in, self);
/* head */
req = iov[0].iov_base;
- /* block */
- block_cnt = 0;
-
- for (i = 1; i < out + in - 1; i++) {
- block = iov[i].iov_base;
- block_len = iov[i].iov_len;
-
- switch (req->type) {
- case VIRTIO_BLK_T_IN:
- err = disk_image__read_sector(self->disk_image, req->sector, block, block_len);
- if (err)
- io_error = true;
- break;
- case VIRTIO_BLK_T_OUT:
- err = disk_image__write_sector(self->disk_image, req->sector, block, block_len);
- if (err)
- io_error = true;
- break;
- default:
- warning("request type %d", req->type);
- io_error = true;
- }
-
- req->sector += block_len >> SECTOR_SHIFT;
- block_cnt += block_len;
- }
+ if (req->type == VIRTIO_BLK_T_IN)
+ block_cnt = disk_image__read_sector_sg(self->disk_image, req->sector, iov + 1, in + out - 2);
+ else if (req->type == VIRTIO_BLK_T_OUT)
+ block_cnt = disk_image__write_sector_sg(self->disk_image, req->sector, iov + 1, in + out - 2);
Please us switch statement like in the above loop instead of if-else and
retain the warning.
/* status */
status = iov[out + in - 1].iov_base;
- *status = io_error ? VIRTIO_BLK_S_IOERR : VIRTIO_BLK_S_OK;
+ *status = (block_cnt == (size_t)-1) ? VIRTIO_BLK_S_IOERR : VIRTIO_BLK_S_OK;
virt_queue__set_used_elem(queue, head, block_cnt);
--
1.7.5.rc1
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