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 <[email protected]> --- 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 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
