On 02/19/2013 03:56 PM, Rusty Russell wrote:
> From: Paolo Bonzini <pbonz...@redhat.com>
>
> (This is a respin of Paolo Bonzini's patch, but it calls
> virtqueue_add_sgs() instead of his multi-part API).
>
> This is similar to the previous patch, but a bit more radical
> because the bio and req paths now share the buffer construction
> code. Because the req path doesn't use vbr->sg, however, we
> need to add a couple of arguments to __virtblk_add_req.
>
> We also need to teach __virtblk_add_req how to build SCSI command
> requests.
>
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> Signed-off-by: Rusty Russell <ru...@rustcorp.com.au>
Reviewed-by: Asias He <as...@redhat.com>
> ---
> drivers/block/virtio_blk.c | 69
> +++++++++++++++++++++-----------------------
> 1 file changed, 33 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index e27bc6c..523a70f 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -102,19 +102,40 @@ static inline struct virtblk_req
> *virtblk_alloc_req(struct virtio_blk *vblk,
> }
>
> static int __virtblk_add_req(struct virtqueue *vq,
> - struct virtblk_req *vbr)
> + struct virtblk_req *vbr,
> + struct scatterlist *data_sg,
> + unsigned data_nents)
> {
> - struct scatterlist hdr, tailer, *sgs[3];
> + struct scatterlist hdr, tailer, cmd, sense, inhdr, *sgs[6];
> unsigned int num_out = 0, num_in = 0;
> + int type = vbr->out_hdr.type & ~VIRTIO_BLK_T_OUT;
>
> sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));
> sgs[num_out++] = &hdr;
>
> - if (vbr->nents) {
> + /*
> + * If this is a packet command we need a couple of additional headers.
> + * Behind the normal outhdr we put a segment with the scsi command
> + * block, and before the normal inhdr we put the sense data and the
> + * inhdr with additional status information.
> + */
> + if (type == VIRTIO_BLK_T_SCSI_CMD) {
> + sg_init_one(&cmd, vbr->req->cmd, vbr->req->cmd_len);
> + sgs[num_out++] = &cmd;
> + }
> +
> + if (data_nents) {
> if (vbr->out_hdr.type & VIRTIO_BLK_T_OUT)
> - sgs[num_out++] = vbr->sg;
> + sgs[num_out++] = data_sg;
> else
> - sgs[num_out + num_in++] = vbr->sg;
> + sgs[num_out + num_in++] = data_sg;
> + }
> +
> + if (type == VIRTIO_BLK_T_SCSI_CMD) {
> + sg_init_one(&sense, vbr->req->sense, SCSI_SENSE_BUFFERSIZE);
> + sgs[num_out + num_in++] = &sense;
> + sg_init_one(&inhdr, &vbr->in_hdr, sizeof(vbr->in_hdr));
> + sgs[num_out + num_in++] = &inhdr;
> }
>
> sg_init_one(&tailer, &vbr->status, sizeof(vbr->status));
> @@ -130,7 +151,8 @@ static void virtblk_add_req(struct virtblk_req *vbr)
> int ret;
>
> spin_lock_irq(vblk->disk->queue->queue_lock);
> - while (unlikely((ret = __virtblk_add_req(vblk->vq, vbr)) < 0)) {
> + while (unlikely((ret = __virtblk_add_req(vblk->vq, vbr, vbr->sg,
> + vbr->nents)) < 0)) {
> prepare_to_wait_exclusive(&vblk->queue_wait, &wait,
> TASK_UNINTERRUPTIBLE);
>
> @@ -283,7 +305,7 @@ static void virtblk_done(struct virtqueue *vq)
> static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
> struct request *req)
> {
> - unsigned long num, out = 0, in = 0;
> + unsigned int num;
> struct virtblk_req *vbr;
>
> vbr = virtblk_alloc_req(vblk, GFP_ATOMIC);
> @@ -320,40 +342,15 @@ static bool do_req(struct request_queue *q, struct
> virtio_blk *vblk,
> }
> }
>
> - sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr));
> -
> - /*
> - * If this is a packet command we need a couple of additional headers.
> - * Behind the normal outhdr we put a segment with the scsi command
> - * block, and before the normal inhdr we put the sense data and the
> - * inhdr with additional status information before the normal inhdr.
> - */
> - if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC)
> - sg_set_buf(&vblk->sg[out++], vbr->req->cmd, vbr->req->cmd_len);
> -
> - num = blk_rq_map_sg(q, vbr->req, vblk->sg + out);
> -
> - if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC) {
> - sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense,
> SCSI_SENSE_BUFFERSIZE);
> - sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr,
> - sizeof(vbr->in_hdr));
> - }
> -
> - sg_set_buf(&vblk->sg[num + out + in++], &vbr->status,
> - sizeof(vbr->status));
> -
> + num = blk_rq_map_sg(q, vbr->req, vblk->sg);
> if (num) {
> - if (rq_data_dir(vbr->req) == WRITE) {
> + if (rq_data_dir(vbr->req) == WRITE)
> vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
> - out += num;
> - } else {
> + else
> vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
> - in += num;
> - }
> }
>
> - if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr,
> - GFP_ATOMIC) < 0) {
> + if (__virtblk_add_req(vblk->vq, vbr, vblk->sg, num) < 0) {
> mempool_free(vbr, vblk->pool);
> return false;
> }
>
--
Asias
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