Commit 2bd37f0f authored by Paolo Bonzini's avatar Paolo Bonzini Committed by James Bottomley
Browse files

[SCSI] virtio-scsi: split scatterlist per target 



To improve performance for I/O to different targets, add a separate
scatterlist for each of them.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
parent bce750b1

drivers/scsi/virtio_scsi.c

+94 −47
Original line number Diff line number Diff line
@@ -50,18 +50,24 @@ struct virtio_scsi_vq { 
	struct virtqueue *vq;

};



/* Per-target queue state */

struct virtio_scsi_target_state {

	/* Protects sg.  Lock hierarchy is tgt_lock -> vq_lock.  */

	spinlock_t tgt_lock;



	/* For sglist construction when adding commands to the virtqueue.  */

	struct scatterlist sg[];

};



/* Driver instance state */

struct virtio_scsi {

	/* Protects sg[].  The lock hierarchy is sg_lock -> vq_lock. */

	spinlock_t sg_lock;



	struct virtio_device *vdev;



	struct virtio_scsi_vq ctrl_vq;

	struct virtio_scsi_vq event_vq;

	struct virtio_scsi_vq req_vq;



	/* For sglist construction when adding commands to the virtqueue.  */

	struct scatterlist sg[];

	struct virtio_scsi_target_state *tgt[];

};



static struct kmem_cache *virtscsi_cmd_cache;
@@ -230,25 +236,17 @@ static void virtscsi_map_sgl(struct scatterlist *sg, unsigned int *p_idx, 
 * @req_size	: size of the request buffer

 * @resp_size	: size of the response buffer

 *

 * Called with vq_lock held.

 * Called with tgt_lock held.

 */

static void virtscsi_map_cmd(struct virtio_scsi *vscsi,

static void virtscsi_map_cmd(struct virtio_scsi_target_state *tgt,

			     struct virtio_scsi_cmd *cmd,

			     unsigned *out_num, unsigned *in_num,

			     size_t req_size, size_t resp_size)

{

	struct scsi_cmnd *sc = cmd->sc;

	struct scatterlist *sg = vscsi->sg;

	struct scatterlist *sg = tgt->sg;

	unsigned int idx = 0;



	if (sc) {

		struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev);

		BUG_ON(scsi_sg_count(sc) > shost->sg_tablesize);



		/* TODO: check feature bit and fail if unsupported?  */

		BUG_ON(sc->sc_data_direction == DMA_BIDIRECTIONAL);

	}



	/* Request header.  */

	sg_set_buf(&sg[idx++], &cmd->req, req_size);
@@ -268,7 +266,8 @@ static void virtscsi_map_cmd(struct virtio_scsi *vscsi, 
	*in_num = idx - *out_num;

}



static int virtscsi_kick_cmd(struct virtio_scsi *vscsi, struct virtio_scsi_vq *vq,

static int virtscsi_kick_cmd(struct virtio_scsi_target_state *tgt,

			     struct virtio_scsi_vq *vq,

			     struct virtio_scsi_cmd *cmd,

			     size_t req_size, size_t resp_size, gfp_t gfp)

{
@@ -276,12 +275,12 @@ static int virtscsi_kick_cmd(struct virtio_scsi *vscsi, struct virtio_scsi_vq *v 
	unsigned long flags;

	int ret;



	spin_lock_irqsave(&vscsi->sg_lock, flags);

	virtscsi_map_cmd(vscsi, cmd, &out_num, &in_num, req_size, resp_size);

	spin_lock_irqsave(&tgt->tgt_lock, flags);

	virtscsi_map_cmd(tgt, cmd, &out_num, &in_num, req_size, resp_size);



	spin_lock(&vq->vq_lock);

	ret = virtqueue_add_buf(vq->vq, vscsi->sg, out_num, in_num, cmd, gfp);

	spin_unlock(&vscsi->sg_lock);

	ret = virtqueue_add_buf(vq->vq, tgt->sg, out_num, in_num, cmd, gfp);

	spin_unlock(&tgt->tgt_lock);

	if (ret >= 0)

		ret = virtqueue_kick_prepare(vq->vq);
@@ -295,9 +294,16 @@ static int virtscsi_kick_cmd(struct virtio_scsi *vscsi, struct virtio_scsi_vq *v 
static int virtscsi_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *sc)

{

	struct virtio_scsi *vscsi = shost_priv(sh);

	struct virtio_scsi_target_state *tgt = vscsi->tgt[sc->device->id];

	struct virtio_scsi_cmd *cmd;

	int ret;



	struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev);

	BUG_ON(scsi_sg_count(sc) > shost->sg_tablesize);



	/* TODO: check feature bit and fail if unsupported?  */

	BUG_ON(sc->sc_data_direction == DMA_BIDIRECTIONAL);



	dev_dbg(&sc->device->sdev_gendev,

		"cmd %p CDB: %#02x\n", sc, sc->cmnd[0]);
@@ -322,7 +328,7 @@ static int virtscsi_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *sc) 
	BUG_ON(sc->cmd_len > VIRTIO_SCSI_CDB_SIZE);

	memcpy(cmd->req.cmd.cdb, sc->cmnd, sc->cmd_len);



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

	if (virtscsi_kick_cmd(tgt, &vscsi->req_vq, cmd,

			      sizeof cmd->req.cmd, sizeof cmd->resp.cmd,

			      GFP_ATOMIC) >= 0)

		ret = 0;
@@ -334,10 +340,11 @@ static int virtscsi_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *sc) 
static int virtscsi_tmf(struct virtio_scsi *vscsi, struct virtio_scsi_cmd *cmd)

{

	DECLARE_COMPLETION_ONSTACK(comp);

	struct virtio_scsi_target_state *tgt = vscsi->tgt[cmd->sc->device->id];

	int ret = FAILED;



	cmd->comp = &comp;

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

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

			      sizeof cmd->req.tmf, sizeof cmd->resp.tmf,

			      GFP_NOIO) < 0)

		goto out;
@@ -437,11 +444,49 @@ static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq, 
	virtscsi_vq->vq = vq;

}



static struct virtio_scsi_target_state *virtscsi_alloc_tgt(

	struct virtio_device *vdev, int sg_elems)

{

	struct virtio_scsi_target_state *tgt;

	gfp_t gfp_mask = GFP_KERNEL;



	/* We need extra sg elements at head and tail.  */

	tgt = kmalloc(sizeof(*tgt) + sizeof(tgt->sg[0]) * (sg_elems + 2),

		      gfp_mask);



	if (!tgt)

		return NULL;



	spin_lock_init(&tgt->tgt_lock);

	sg_init_table(tgt->sg, sg_elems + 2);

	return tgt;

}



static void virtscsi_remove_vqs(struct virtio_device *vdev)

{

	struct Scsi_Host *sh = virtio_scsi_host(vdev);

	struct virtio_scsi *vscsi = shost_priv(sh);

	u32 i, num_targets;



	/* Stop all the virtqueues. */

	vdev->config->reset(vdev);



	num_targets = sh->max_id;

	for (i = 0; i < num_targets; i++) {

		kfree(vscsi->tgt[i]);

		vscsi->tgt[i] = NULL;

	}



	vdev->config->del_vqs(vdev);

}



static int virtscsi_init(struct virtio_device *vdev,

			 struct virtio_scsi *vscsi)

			 struct virtio_scsi *vscsi, int num_targets)

{

	int err;

	struct virtqueue *vqs[3];

	u32 i, sg_elems;



	vq_callback_t *callbacks[] = {

		virtscsi_ctrl_done,

		virtscsi_event_done,
@@ -464,7 +509,23 @@ static int virtscsi_init(struct virtio_device *vdev, 


	virtscsi_config_set(vdev, cdb_size, VIRTIO_SCSI_CDB_SIZE);

	virtscsi_config_set(vdev, sense_size, VIRTIO_SCSI_SENSE_SIZE);

	return 0;



	/* We need to know how many segments before we allocate.  */

	sg_elems = virtscsi_config_get(vdev, seg_max) ?: 1;



	for (i = 0; i < num_targets; i++) {

		vscsi->tgt[i] = virtscsi_alloc_tgt(vdev, sg_elems);

		if (!vscsi->tgt[i]) {

			err = -ENOMEM;

			goto out;

		}

	}

	err = 0;



out:

	if (err)

		virtscsi_remove_vqs(vdev);

	return err;

}



static int __devinit virtscsi_probe(struct virtio_device *vdev)
@@ -472,31 +533,25 @@ static int __devinit virtscsi_probe(struct virtio_device *vdev) 
	struct Scsi_Host *shost;

	struct virtio_scsi *vscsi;

	int err;

	u32 sg_elems;

	u32 sg_elems, num_targets;

	u32 cmd_per_lun;



	/* We need to know how many segments before we allocate.

	 * We need an extra sg elements at head and tail.

	 */

	sg_elems = virtscsi_config_get(vdev, seg_max) ?: 1;



	/* Allocate memory and link the structs together.  */

	num_targets = virtscsi_config_get(vdev, max_target) + 1;

	shost = scsi_host_alloc(&virtscsi_host_template,

		sizeof(*vscsi) + sizeof(vscsi->sg[0]) * (sg_elems + 2));

		sizeof(*vscsi)

		+ num_targets * sizeof(struct virtio_scsi_target_state));



	if (!shost)

		return -ENOMEM;



	sg_elems = virtscsi_config_get(vdev, seg_max) ?: 1;

	shost->sg_tablesize = sg_elems;

	vscsi = shost_priv(shost);

	vscsi->vdev = vdev;

	vdev->priv = shost;



	/* Random initializations.  */

	spin_lock_init(&vscsi->sg_lock);

	sg_init_table(vscsi->sg, sg_elems + 2);



	err = virtscsi_init(vdev, vscsi);

	err = virtscsi_init(vdev, vscsi, num_targets);

	if (err)

		goto virtscsi_init_failed;
@@ -504,7 +559,7 @@ static int __devinit virtscsi_probe(struct virtio_device *vdev) 
	shost->cmd_per_lun = min_t(u32, cmd_per_lun, shost->can_queue);

	shost->max_sectors = virtscsi_config_get(vdev, max_sectors) ?: 0xFFFF;

	shost->max_lun = virtscsi_config_get(vdev, max_lun) + 1;

	shost->max_id = virtscsi_config_get(vdev, max_target) + 1;

	shost->max_id = num_targets;

	shost->max_channel = 0;

	shost->max_cmd_len = VIRTIO_SCSI_CDB_SIZE;

	err = scsi_add_host(shost, &vdev->dev);
@@ -522,14 +577,6 @@ static int __devinit virtscsi_probe(struct virtio_device *vdev) 
	return err;

}



static void virtscsi_remove_vqs(struct virtio_device *vdev)

{

	/* Stop all the virtqueues. */

	vdev->config->reset(vdev);



	vdev->config->del_vqs(vdev);

}



static void __devexit virtscsi_remove(struct virtio_device *vdev)

{

	struct Scsi_Host *shost = virtio_scsi_host(vdev);
@@ -552,7 +599,7 @@ static int virtscsi_restore(struct virtio_device *vdev) 
	struct Scsi_Host *sh = virtio_scsi_host(vdev);

	struct virtio_scsi *vscsi = shost_priv(sh);



	return virtscsi_init(vdev, vscsi);

	return virtscsi_init(vdev, vscsi, sh->max_id);

}

#endif