[SLOF] [PATCH 3/4] virtio: Implement block write support

[Nikunj A Dadhania]

Thomas Huth <thuth at redhat.com> writes:

> Rework the virtio-block code a little bit to provide
> block write access, too.
>
> Signed-off-by: Thomas Huth <thuth at redhat.com>
> ---
>  board-qemu/slof/virtio-block.fs |  8 ++++++++
>  lib/libvirtio/virtio-blk.c      | 24 +++++++++++++-----------
>  lib/libvirtio/virtio-blk.h      |  3 ++-
>  lib/libvirtio/virtio.code       | 11 ++++++++++-
>  lib/libvirtio/virtio.in         |  1 +
>  5 files changed, 34 insertions(+), 13 deletions(-)
>
> diff --git a/board-qemu/slof/virtio-block.fs b/board-qemu/slof/virtio-block.fs
> index bc9013e..e2e3def 100644
> --- a/board-qemu/slof/virtio-block.fs
> +++ b/board-qemu/slof/virtio-block.fs
> @@ -49,6 +49,10 @@ virtio-setup-vd VALUE virtiodev
>     virtiodev virtio-blk-read
>  ;
>
> +: write-blocks  ( addr block# #blocks -- #written )
> +   virtiodev virtio-blk-write
> +;
> +
>  \ Standard node "open" function
>  : open  ( -- okay? )
>     open 0= IF false EXIT THEN
> @@ -79,6 +83,10 @@ virtio-setup-vd VALUE virtiodev
>     s" read" deblocker @ $call-method
>  ;
>
> +: write ( addr len -- actual )
> +    s" write" deblocker @ $call-method
> +;
> +
>  \ Set disk alias if none is set yet
>  : (set-alias)
>     s" disk" get-next-alias ?dup IF
> diff --git a/lib/libvirtio/virtio-blk.c b/lib/libvirtio/virtio-blk.c
> index 07ec104..bc554f3 100644
> --- a/lib/libvirtio/virtio-blk.c
> +++ b/lib/libvirtio/virtio-blk.c
> @@ -112,15 +112,17 @@ static void fill_blk_hdr(struct virtio_blk_req *blkhdr, bool is_modern,
>  }
>
>  /**
> - * Read blocks
> + * Read / write blocks
>   * @param  reg  pointer to "reg" property
>   * @param  buf  pointer to destination buffer
> - * @param  blocknum  block number of the first block that should be read
> - * @param  cnt  amount of blocks that should be read
> - * @return number of blocks that have been read successfully
> + * @param  blocknum  block number of the first block that should be transfered
> + * @param  cnt  amount of blocks that should be transfered
> + * @param  type  VIRTIO_BLK_T_OUT for write, VIRTIO_BLK_T_IN for read transfers
> + * @return number of blocks that have been transfered successfully
>   */
>  int
> -virtioblk_read(struct virtio_device *dev, char *buf, uint64_t blocknum, long cnt)
> +virtioblk_transfer(struct virtio_device *dev, char *buf, uint64_t blocknum,
> +                   long cnt, unsigned int type)
>  {
>  	struct vring_desc *desc;
>  	int id;
> @@ -136,7 +138,7 @@ virtioblk_read(struct virtio_device *dev, char *buf, uint64_t blocknum, long cnt
>  	uint16_t last_used_idx, avail_idx;
>  	int blk_size = DEFAULT_SECTOR_SIZE;
>
> -	//printf("virtioblk_read: dev=%p buf=%p blocknum=%li count=%li\n",
> +	//printf("virtioblk_transfer: dev=%p buf=%p blocknum=%lli count=%li\n",
>  	//	dev, buf, blocknum, cnt);
>
>  	/* Check whether request is within disk capacity */
> @@ -144,7 +146,7 @@ virtioblk_read(struct virtio_device *dev, char *buf, uint64_t blocknum, long cnt
>  			offset_of(struct virtio_blk_cfg, capacity),
>  			sizeof(capacity));
>  	if (blocknum + cnt - 1 > capacity) {
> -		puts("virtioblk_read: Access beyond end of device!");
> +		puts("virtioblk_transfer: Access beyond end of device!");
>  		return 0;
>  	}
>
> @@ -152,7 +154,7 @@ virtioblk_read(struct virtio_device *dev, char *buf, uint64_t blocknum, long cnt
>  			offset_of(struct virtio_blk_cfg, blk_size),
>  			sizeof(blk_size));
>  	if (blk_size % DEFAULT_SECTOR_SIZE) {
> -		fprintf(stderr, "virtio-blk: Unaligned sector read %d\n", blk_size);
> +		fprintf(stderr, "virtio-blk: Unaligned sector size %d\n", blk_size);
>  		return 0;
>  	}
>
> @@ -167,7 +169,7 @@ virtioblk_read(struct virtio_device *dev, char *buf, uint64_t blocknum, long cnt
>  	current_used_idx = &vq_used->idx;
>
>  	/* Set up header */
> -	fill_blk_hdr(&blkhdr, dev->is_modern, VIRTIO_BLK_T_IN | VIRTIO_BLK_T_BARRIER,
> +	fill_blk_hdr(&blkhdr, dev->is_modern, type | VIRTIO_BLK_T_BARRIER,
>  		     1, blocknum * blk_size / DEFAULT_SECTOR_SIZE);
>
>  	/* Determine descriptor index */
> @@ -182,7 +184,7 @@ virtioblk_read(struct virtio_device *dev, char *buf, uint64_t blocknum, long cnt
>  	/* Set up virtqueue descriptor for data */
>  	desc = &vq_desc[(id + 1) % vq_size];
>  	virtio_fill_desc(desc, dev->is_modern, (uint64_t)buf, cnt * blk_size,
> -			 VRING_DESC_F_NEXT | VRING_DESC_F_WRITE,
> +			 VRING_DESC_F_NEXT | ((type & 1) ? 0 : VRING_DESC_F_WRITE),
>  			 (id + 2) % vq_size);
>
>  	/* Set up virtqueue descriptor for status */
> @@ -209,7 +211,7 @@ virtioblk_read(struct virtio_device *dev, char *buf, uint64_t blocknum, long cnt
>  	if (status == 0)
>  		return cnt;
>
> -	printf("virtioblk_read failed! status = %i\n", status);
> +	printf("virtioblk_transfer failed! status = %i\n", status);

Including type (In/Out) in the above error prints will help in debugging.

Regards
Nikunj