1 files changed, 16 insertions, 113 deletions

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 7c28e8d4955a..45d04631888a 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -91,9 +91,6 @@ struct virtio_scsi_vq {
 struct virtio_scsi_target_state {
 	seqcount_t tgt_seq;
 
-	/* Count of outstanding requests. */
-	atomic_t reqs;
-
 	/* Currently active virtqueue for requests sent to this target. */
 	struct virtio_scsi_vq *req_vq;
 };
@@ -152,8 +149,6 @@ static void virtscsi_complete_cmd(struct virtio_scsi *vscsi, void *buf)
 	struct virtio_scsi_cmd *cmd = buf;
 	struct scsi_cmnd *sc = cmd->sc;
 	struct virtio_scsi_cmd_resp *resp = &cmd->resp.cmd;
-	struct virtio_scsi_target_state *tgt =
-				scsi_target(sc->device)->hostdata;
 
 	dev_dbg(&sc->device->sdev_gendev,
 		"cmd %p response %u status %#02x sense_len %u\n",
@@ -210,8 +205,6 @@ static void virtscsi_complete_cmd(struct virtio_scsi *vscsi, void *buf)
 	}
 
 	sc->scsi_done(sc);
-
-	atomic_dec(&tgt->reqs);
 }
 
 static void virtscsi_vq_done(struct virtio_scsi *vscsi,
@@ -529,11 +522,20 @@ static void virtio_scsi_init_hdr_pi(struct virtio_device *vdev,
 }
 #endif
 
-static int virtscsi_queuecommand(struct virtio_scsi *vscsi,
-				 struct virtio_scsi_vq *req_vq,
+static struct virtio_scsi_vq *virtscsi_pick_vq_mq(struct virtio_scsi *vscsi,
+						  struct scsi_cmnd *sc)
+{
+	u32 tag = blk_mq_unique_tag(sc->request);
+	u16 hwq = blk_mq_unique_tag_to_hwq(tag);
+
+	return &vscsi->req_vqs[hwq];
+}
+
+static int virtscsi_queuecommand(struct Scsi_Host *shost,
 				 struct scsi_cmnd *sc)
 {
-	struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev);
+	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);
 	unsigned long flags;
 	int req_size;
@@ -576,79 +578,6 @@ static int virtscsi_queuecommand(struct virtio_scsi *vscsi,
 	return 0;
 }
 
-static int virtscsi_queuecommand_single(struct Scsi_Host *sh,
-					struct scsi_cmnd *sc)
-{
-	struct virtio_scsi *vscsi = shost_priv(sh);
-	struct virtio_scsi_target_state *tgt =
-				scsi_target(sc->device)->hostdata;
-
-	atomic_inc(&tgt->reqs);
-	return virtscsi_queuecommand(vscsi, &vscsi->req_vqs[0], sc);
-}
-
-static struct virtio_scsi_vq *virtscsi_pick_vq_mq(struct virtio_scsi *vscsi,
-						  struct scsi_cmnd *sc)
-{
-	u32 tag = blk_mq_unique_tag(sc->request);
-	u16 hwq = blk_mq_unique_tag_to_hwq(tag);
-
-	return &vscsi->req_vqs[hwq];
-}
-
-static struct virtio_scsi_vq *virtscsi_pick_vq(struct virtio_scsi *vscsi,
-					       struct virtio_scsi_target_state *tgt)
-{
-	struct virtio_scsi_vq *vq;
-	unsigned long flags;
-	u32 queue_num;
-
-	local_irq_save(flags);
-	if (atomic_inc_return(&tgt->reqs) > 1) {
-		unsigned long seq;
-
-		do {
-			seq = read_seqcount_begin(&tgt->tgt_seq);
-			vq = tgt->req_vq;
-		} while (read_seqcount_retry(&tgt->tgt_seq, seq));
-	} else {
-		/* no writes can be concurrent because of atomic_t */
-		write_seqcount_begin(&tgt->tgt_seq);
-
-		/* keep previous req_vq if a reader just arrived */
-		if (unlikely(atomic_read(&tgt->reqs) > 1)) {
-			vq = tgt->req_vq;
-			goto unlock;
-		}
-
-		queue_num = smp_processor_id();
-		while (unlikely(queue_num >= vscsi->num_queues))
-			queue_num -= vscsi->num_queues;
-		tgt->req_vq = vq = &vscsi->req_vqs[queue_num];
- unlock:
-		write_seqcount_end(&tgt->tgt_seq);
-	}
-	local_irq_restore(flags);
-
-	return vq;
-}
-
-static int virtscsi_queuecommand_multi(struct Scsi_Host *sh,
-				       struct scsi_cmnd *sc)
-{
-	struct virtio_scsi *vscsi = shost_priv(sh);
-	struct virtio_scsi_target_state *tgt =
-				scsi_target(sc->device)->hostdata;
-	struct virtio_scsi_vq *req_vq;
-
-	if (shost_use_blk_mq(sh))
-		req_vq = virtscsi_pick_vq_mq(vscsi, sc);
-	else
-		req_vq = virtscsi_pick_vq(vscsi, tgt);
-
-	return virtscsi_queuecommand(vscsi, req_vq, sc);
-}
-
 static int virtscsi_tmf(struct virtio_scsi *vscsi, struct virtio_scsi_cmd *cmd)
 {
 	DECLARE_COMPLETION_ONSTACK(comp);
@@ -775,7 +704,6 @@ static int virtscsi_target_alloc(struct scsi_target *starget)
 		return -ENOMEM;
 
 	seqcount_init(&tgt->tgt_seq);
-	atomic_set(&tgt->reqs, 0);
 	tgt->req_vq = &vscsi->req_vqs[0];
 
 	starget->hostdata = tgt;
@@ -805,33 +733,13 @@ static enum blk_eh_timer_return virtscsi_eh_timed_out(struct scsi_cmnd *scmnd)
 	return BLK_EH_RESET_TIMER;
 }
 
-static struct scsi_host_template virtscsi_host_template_single = {
-	.module = THIS_MODULE,
-	.name = "Virtio SCSI HBA",
-	.proc_name = "virtio_scsi",
-	.this_id = -1,
-	.cmd_size = sizeof(struct virtio_scsi_cmd),
-	.queuecommand = virtscsi_queuecommand_single,
-	.change_queue_depth = virtscsi_change_queue_depth,
-	.eh_abort_handler = virtscsi_abort,
-	.eh_device_reset_handler = virtscsi_device_reset,
-	.eh_timed_out = virtscsi_eh_timed_out,
-	.slave_alloc = virtscsi_device_alloc,
-
-	.dma_boundary = UINT_MAX,
-	.use_clustering = ENABLE_CLUSTERING,
-	.target_alloc = virtscsi_target_alloc,
-	.target_destroy = virtscsi_target_destroy,
-	.track_queue_depth = 1,
-};
-
-static struct scsi_host_template virtscsi_host_template_multi = {
+static struct scsi_host_template virtscsi_host_template = {
 	.module = THIS_MODULE,
 	.name = "Virtio SCSI HBA",
 	.proc_name = "virtio_scsi",
 	.this_id = -1,
 	.cmd_size = sizeof(struct virtio_scsi_cmd),
-	.queuecommand = virtscsi_queuecommand_multi,
+	.queuecommand = virtscsi_queuecommand,
 	.change_queue_depth = virtscsi_change_queue_depth,
 	.eh_abort_handler = virtscsi_abort,
 	.eh_device_reset_handler = virtscsi_device_reset,
@@ -844,6 +752,7 @@ static struct scsi_host_template virtscsi_host_template_multi = {
 	.target_destroy = virtscsi_target_destroy,
 	.map_queues = virtscsi_map_queues,
 	.track_queue_depth = 1,
+	.force_blk_mq = 1,
 };
 
 #define virtscsi_config_get(vdev, fld) \
@@ -936,7 +845,6 @@ static int virtscsi_probe(struct virtio_device *vdev)
 	u32 sg_elems, num_targets;
 	u32 cmd_per_lun;
 	u32 num_queues;
-	struct scsi_host_template *hostt;
 
 	if (!vdev->config->get) {
 		dev_err(&vdev->dev, "%s failure: config access disabled\n",
@@ -949,12 +857,7 @@ static int virtscsi_probe(struct virtio_device *vdev)
 
 	num_targets = virtscsi_config_get(vdev, max_target) + 1;
 
-	if (num_queues == 1)
-		hostt = &virtscsi_host_template_single;
-	else
-		hostt = &virtscsi_host_template_multi;
-
-	shost = scsi_host_alloc(hostt,
+	shost = scsi_host_alloc(&virtscsi_host_template,
 		sizeof(*vscsi) + sizeof(vscsi->req_vqs[0]) * num_queues);
 	if (!shost)
 		return -ENOMEM;