Commit 9e5470fe authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Martin K. Petersen
Browse files

scsi: virtio_scsi: implement request batching 



Adding the command and kicking the virtqueue so far was done one after
another.  Make the kick optional, so that we can take into account
SCMD_LAST.  We also need a commit_rqs callback to kick the device if
blk-mq aborts the submission before the last request is reached.

Suggested-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 8930a6c2

drivers/scsi/virtio_scsi.c

+40 −15
Original line number Diff line number Diff line
@@ -369,14 +369,7 @@ static void virtscsi_event_done(struct virtqueue *vq) 
	virtscsi_vq_done(vscsi, &vscsi->event_vq, virtscsi_complete_event);

};



/**

 * virtscsi_add_cmd - add a virtio_scsi_cmd to a virtqueue

 * @vq		: the struct virtqueue we're talking about

 * @cmd		: command structure

 * @req_size	: size of the request buffer

 * @resp_size	: size of the response buffer

 */

static int virtscsi_add_cmd(struct virtqueue *vq,

static int __virtscsi_add_cmd(struct virtqueue *vq,

			    struct virtio_scsi_cmd *cmd,

			    size_t req_size, size_t resp_size)

{
@@ -421,17 +414,39 @@ static int virtscsi_add_cmd(struct virtqueue *vq, 
	return virtqueue_add_sgs(vq, sgs, out_num, in_num, cmd, GFP_ATOMIC);

}



static int virtscsi_kick_cmd(struct virtio_scsi_vq *vq,

static void virtscsi_kick_vq(struct virtio_scsi_vq *vq)

{

	bool needs_kick;

	unsigned long flags;



	spin_lock_irqsave(&vq->vq_lock, flags);

	needs_kick = virtqueue_kick_prepare(vq->vq);

	spin_unlock_irqrestore(&vq->vq_lock, flags);



	if (needs_kick)

		virtqueue_notify(vq->vq);

}



/**

 * virtscsi_add_cmd - add a virtio_scsi_cmd to a virtqueue, optionally kick it

 * @vq		: the struct virtqueue we're talking about

 * @cmd		: command structure

 * @req_size	: size of the request buffer

 * @resp_size	: size of the response buffer

 * @kick	: whether to kick the virtqueue immediately

 */

static int virtscsi_add_cmd(struct virtio_scsi_vq *vq,

			     struct virtio_scsi_cmd *cmd,

			     size_t req_size, size_t resp_size)

			     size_t req_size, size_t resp_size,

			     bool kick)

{

	unsigned long flags;

	int err;

	bool needs_kick = false;



	spin_lock_irqsave(&vq->vq_lock, flags);

	err = virtscsi_add_cmd(vq->vq, cmd, req_size, resp_size);

	if (!err)

	err = __virtscsi_add_cmd(vq->vq, cmd, req_size, resp_size);

	if (!err && kick)

		needs_kick = virtqueue_kick_prepare(vq->vq);



	spin_unlock_irqrestore(&vq->vq_lock, flags);
@@ -496,6 +511,7 @@ static int virtscsi_queuecommand(struct Scsi_Host *shost, 
	struct virtio_scsi *vscsi = shost_priv(shost);

	struct virtio_scsi_vq *req_vq = virtscsi_pick_vq_mq(vscsi, sc);

	struct virtio_scsi_cmd *cmd = scsi_cmd_priv(sc);

	bool kick;

	unsigned long flags;

	int req_size;

	int ret;
@@ -525,7 +541,8 @@ static int virtscsi_queuecommand(struct Scsi_Host *shost, 
		req_size = sizeof(cmd->req.cmd);

	}



	ret = virtscsi_kick_cmd(req_vq, cmd, req_size, sizeof(cmd->resp.cmd));

	kick = (sc->flags & SCMD_LAST) != 0;

	ret = virtscsi_add_cmd(req_vq, cmd, req_size, sizeof(cmd->resp.cmd), kick);

	if (ret == -EIO) {

		cmd->resp.cmd.response = VIRTIO_SCSI_S_BAD_TARGET;

		spin_lock_irqsave(&req_vq->vq_lock, flags);
@@ -543,8 +560,8 @@ static int virtscsi_tmf(struct virtio_scsi *vscsi, struct virtio_scsi_cmd *cmd) 
	int ret = FAILED;



	cmd->comp = &comp;

	if (virtscsi_kick_cmd(&vscsi->ctrl_vq, cmd,

			      sizeof cmd->req.tmf, sizeof cmd->resp.tmf) < 0)

	if (virtscsi_add_cmd(&vscsi->ctrl_vq, cmd,

			      sizeof cmd->req.tmf, sizeof cmd->resp.tmf, true) < 0)

		goto out;



	wait_for_completion(&comp);
@@ -658,6 +675,13 @@ static int virtscsi_map_queues(struct Scsi_Host *shost) 
	return blk_mq_virtio_map_queues(qmap, vscsi->vdev, 2);

}



static void virtscsi_commit_rqs(struct Scsi_Host *shost, u16 hwq)

{

	struct virtio_scsi *vscsi = shost_priv(shost);



	virtscsi_kick_vq(&vscsi->req_vqs[hwq]);

}



/*

 * The host guarantees to respond to each command, although I/O

 * latencies might be higher than on bare metal.  Reset the timer
@@ -675,6 +699,7 @@ static struct scsi_host_template virtscsi_host_template = { 
	.this_id = -1,

	.cmd_size = sizeof(struct virtio_scsi_cmd),

	.queuecommand = virtscsi_queuecommand,

	.commit_rqs = virtscsi_commit_rqs,

	.change_queue_depth = virtscsi_change_queue_depth,

	.eh_abort_handler = virtscsi_abort,

	.eh_device_reset_handler = virtscsi_device_reset,

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