Commit 20af3cfd authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Rusty Russell
Browse files

virtio-blk: use virtqueue_add_sgs on req path 



(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: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Reviewed-by: default avatarAsias He <asias@redhat.com>
parent 8f39db9d

drivers/block/virtio_blk.c

+33 −36
Original line number Diff line number Diff line
@@ -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, status, *sgs[3];

	struct scatterlist hdr, status, 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(&status, &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;

	}

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