Messages in this thread | | | Date | Wed, 20 Feb 2013 17:20:02 +0800 | From | Asias He <> | Subject | Re: [PATCH 05/16] virtio-blk: use virtqueue_add_sgs on req path |
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On 02/19/2013 03:56 PM, Rusty Russell wrote: > From: Paolo Bonzini <pbonzini@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 <pbonzini@redhat.com> > Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reviewed-by: Asias He <asias@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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