[PATCH 04/13] vhost scsi: use lio wq cmd submission helper

[Mike Christie <michael.christie@oracle.com>]

Convert vhost-scsi to use the lio wq cmd submission helper.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/vhost/scsi.c | 49 +++++++++++++++-----------------------------
 1 file changed, 17 insertions(+), 32 deletions(-)

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 4ce9f00ae10e..99909c6f3960 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -85,7 +85,7 @@ struct vhost_scsi_cmd {
 	/* The number of scatterlists associated with this cmd */
 	u32 tvc_sgl_count;
 	u32 tvc_prot_sgl_count;
-	/* Saved unpacked SCSI LUN for vhost_scsi_submission_work() */
+	/* Saved unpacked SCSI LUN for vhost_scsi_target_queue_cmd() */
 	u32 tvc_lun;
 	/* Pointer to the SGL formatted memory from virtio-scsi */
 	struct scatterlist *tvc_sgl;
@@ -101,8 +101,6 @@ struct vhost_scsi_cmd {
 	struct vhost_scsi_nexus *tvc_nexus;
 	/* The TCM I/O descriptor that is accessed via container_of() */
 	struct se_cmd tvc_se_cmd;
-	/* work item used for cmwq dispatch to vhost_scsi_submission_work() */
-	struct work_struct work;
 	/* Copy of the incoming SCSI command descriptor block (CDB) */
 	unsigned char tvc_cdb[VHOST_SCSI_MAX_CDB_SIZE];
 	/* Sense buffer that will be mapped into outgoing status */
@@ -240,8 +238,6 @@ struct vhost_scsi_ctx {
 	struct iov_iter out_iter;
 };
 
-static struct workqueue_struct *vhost_scsi_workqueue;
-
 /* Global spinlock to protect vhost_scsi TPG list for vhost IOCTL access */
 static DEFINE_MUTEX(vhost_scsi_mutex);
 static LIST_HEAD(vhost_scsi_list);
@@ -782,12 +778,10 @@ static int vhost_scsi_to_tcm_attr(int attr)
 	return TCM_SIMPLE_TAG;
 }
 
-static void vhost_scsi_submission_work(struct work_struct *work)
+static void vhost_scsi_target_queue_cmd(struct vhost_scsi_cmd *cmd)
 {
-	struct vhost_scsi_cmd *cmd =
-		container_of(work, struct vhost_scsi_cmd, work);
-	struct vhost_scsi_nexus *tv_nexus;
 	struct se_cmd *se_cmd = &cmd->tvc_se_cmd;
+	struct vhost_scsi_nexus *tv_nexus;
 	struct scatterlist *sg_ptr, *sg_prot_ptr = NULL;
 	int rc;
 
@@ -805,9 +799,9 @@ static void vhost_scsi_submission_work(struct work_struct *work)
 	tv_nexus = cmd->tvc_nexus;
 
 	se_cmd->tag = 0;
-	rc = target_submit_cmd_map_sgls(se_cmd, tv_nexus->tvn_se_sess,
-			cmd->tvc_cdb, &cmd->tvc_sense_buf[0],
-			cmd->tvc_lun, cmd->tvc_exp_data_len,
+	rc = target_queue_cmd_submit(se_cmd, tv_nexus->tvn_se_sess,
+			&cmd->tvc_sense_buf[0], cmd->tvc_lun,
+			cmd->tvc_exp_data_len,
 			vhost_scsi_to_tcm_attr(cmd->tvc_task_attr),
 			cmd->tvc_data_direction, TARGET_SCF_ACK_KREF,
 			sg_ptr, cmd->tvc_sgl_count, NULL, 0, sg_prot_ptr,
@@ -819,6 +813,14 @@ static void vhost_scsi_submission_work(struct work_struct *work)
 	}
 }
 
+static unsigned char *vhost_scsi_get_cdb(struct se_cmd *se_cmd)
+{
+	struct vhost_scsi_cmd *cmd = container_of(se_cmd, struct vhost_scsi_cmd,
+						  tvc_se_cmd);
+
+	return cmd->tvc_cdb;
+}
+
 static void
 vhost_scsi_send_bad_target(struct vhost_scsi *vs,
 			   struct vhost_virtqueue *vq,
@@ -1132,14 +1134,7 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
 		 * vhost_scsi_queue_data_in() and vhost_scsi_queue_status()
 		 */
 		cmd->tvc_vq_desc = vc.head;
-		/*
-		 * Dispatch cmd descriptor for cmwq execution in process
-		 * context provided by vhost_scsi_workqueue.  This also ensures
-		 * cmd is executed on the same kworker CPU as this vhost
-		 * thread to gain positive L2 cache locality effects.
-		 */
-		INIT_WORK(&cmd->work, vhost_scsi_submission_work);
-		queue_work(vhost_scsi_workqueue, &cmd->work);
+		vhost_scsi_target_queue_cmd(cmd);
 		ret = 0;
 err:
 		/*
@@ -2466,6 +2461,7 @@ static const struct target_core_fabric_ops vhost_scsi_ops = {
 	.queue_status			= vhost_scsi_queue_status,
 	.queue_tm_rsp			= vhost_scsi_queue_tm_rsp,
 	.aborted_task			= vhost_scsi_aborted_task,
+	.get_cdb			= vhost_scsi_get_cdb,
 	/*
 	 * Setup callers for generic logic in target_core_fabric_configfs.c
 	 */
@@ -2489,17 +2485,9 @@ static int __init vhost_scsi_init(void)
 		" on "UTS_RELEASE"\n", VHOST_SCSI_VERSION, utsname()->sysname,
 		utsname()->machine);
 
-	/*
-	 * Use our own dedicated workqueue for submitting I/O into
-	 * target core to avoid contention within system_wq.
-	 */
-	vhost_scsi_workqueue = alloc_workqueue("vhost_scsi", 0, 0);
-	if (!vhost_scsi_workqueue)
-		goto out;
-
 	ret = vhost_scsi_register();
 	if (ret < 0)
-		goto out_destroy_workqueue;
+		goto out;
 
 	ret = target_register_template(&vhost_scsi_ops);
 	if (ret < 0)
@@ -2509,8 +2497,6 @@ static int __init vhost_scsi_init(void)
 
 out_vhost_scsi_deregister:
 	vhost_scsi_deregister();
-out_destroy_workqueue:
-	destroy_workqueue(vhost_scsi_workqueue);
 out:
 	return ret;
 };
@@ -2519,7 +2505,6 @@ static void vhost_scsi_exit(void)
 {
 	target_unregister_template(&vhost_scsi_ops);
 	vhost_scsi_deregister();
-	destroy_workqueue(vhost_scsi_workqueue);
 };
 
 MODULE_DESCRIPTION("VHOST_SCSI series fabric driver");
-- 
2.25.1