* [PATCH 2/2] kvm tools: Add scatter-gather support for disk images
2011-04-16 11:45 [PATCH 1/2 V2] kvm tools: Fix leak in QCOW Sasha Levin
@ 2011-04-16 11:45 ` Sasha Levin
2011-04-16 13:55 ` Pekka Enberg
0 siblings, 1 reply; 3+ messages in thread
From: Sasha Levin @ 2011-04-16 11:45 UTC (permalink / raw)
To: penberg; +Cc: mingo, asias.hejun, gorcunov, kvm, Sasha Levin
Add optional support for scatter-gather to disk_image.
Formats that can't take advantage of scatter-gather fallback to simple IO.
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
---
tools/kvm/disk-image.c | 22 ++++++++++++++++++++
tools/kvm/include/kvm/disk-image.h | 31 ++++++++++++++++++++++++++++
tools/kvm/virtio-blk.c | 39 +++++------------------------------
3 files changed, 59 insertions(+), 33 deletions(-)
diff --git a/tools/kvm/disk-image.c b/tools/kvm/disk-image.c
index 4198ebb..dd54b99 100644
--- a/tools/kvm/disk-image.c
+++ b/tools/kvm/disk-image.c
@@ -72,6 +72,26 @@ static int raw_image__write_sector(struct disk_image *self, uint64_t sector, voi
return 0;
}
+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;
+}
+
+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;
+}
+
static int raw_image__read_sector_ro_mmap(struct disk_image *self, uint64_t sector, void *dst, uint32_t dst_len)
{
uint64_t offset = sector << SECTOR_SHIFT;
@@ -105,6 +125,8 @@ static void raw_image__close_ro_mmap(struct disk_image *self)
static struct disk_image_operations raw_image_ops = {
.read_sector = raw_image__read_sector,
.write_sector = raw_image__write_sector,
+ .read_sector_sg = raw_image__read_sector_sg,
+ .write_sector_sg = raw_image__write_sector_sg
};
static struct disk_image_operations raw_image_ro_mmap_ops = {
diff --git a/tools/kvm/include/kvm/disk-image.h b/tools/kvm/include/kvm/disk-image.h
index 33962c6..a4a96a2 100644
--- a/tools/kvm/include/kvm/disk-image.h
+++ b/tools/kvm/include/kvm/disk-image.h
@@ -3,6 +3,7 @@
#include <stdint.h>
#include <stdbool.h>
+#include <sys/uio.h>
#define SECTOR_SHIFT 9
#define SECTOR_SIZE (1UL << SECTOR_SHIFT)
@@ -12,6 +13,8 @@ struct disk_image;
struct disk_image_operations {
int (*read_sector)(struct disk_image *self, uint64_t sector, void *dst, uint32_t dst_len);
int (*write_sector)(struct disk_image *self, uint64_t sector, void *src, uint32_t src_len);
+ size_t (*read_sector_sg)(struct disk_image *self, uint64_t sector, const struct iovec *iov, int iovcount);
+ size_t (*write_sector_sg)(struct disk_image *self, uint64_t sector, const struct iovec *iov, int iovcount);
void (*close)(struct disk_image *self);
};
@@ -37,4 +40,32 @@ static inline int disk_image__write_sector(struct disk_image *self, uint64_t sec
return self->ops->write_sector(self, sector, src, src_len);
}
+static inline size_t disk_image__read_sector_sg(struct disk_image *self, uint64_t sector, const struct iovec *iov, int iovcount)
+{
+ if (self->ops->read_sector_sg)
+ return self->ops->read_sector_sg(self, sector, iov, iovcount);
+
+ while (iovcount--) {
+ self->ops->read_sector(self, sector, iov->iov_base, iov->iov_len);
+ sector += iov->iov_len >> SECTOR_SHIFT;
+ iov++;
+ }
+
+ return sector << SECTOR_SHIFT;
+}
+
+static inline size_t disk_image__write_sector_sg(struct disk_image *self, uint64_t sector, const struct iovec *iov, int iovcount)
+{
+ if (self->ops->write_sector_sg)
+ return self->ops->write_sector_sg(self, sector, iov, iovcount);
+
+ while (iovcount--) {
+ self->ops->write_sector(self, sector, iov->iov_base, iov->iov_len);
+ sector += iov->iov_len >> SECTOR_SHIFT;
+ iov++;
+ }
+
+ return sector << SECTOR_SHIFT;
+}
+
#endif /* KVM__DISK_IMAGE_H */
diff --git a/tools/kvm/virtio-blk.c b/tools/kvm/virtio-blk.c
index cb344d08..aee3b73 100644
--- a/tools/kvm/virtio-blk.c
+++ b/tools/kvm/virtio-blk.c
@@ -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);
/* 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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