tcm_vhost: Convert I/O path to use target_submit_cmd_map_sgls

This patch converts tcm_vhost to use target_submit_cmd_map_sgls() for
I/O submission and mapping of pre-allocated SGL memory from incoming
virtio-scsi SGL memory -> se_cmd descriptors.

This includes removing the original open-coded fabric uses of target
core callers to support transport_generic_map_mem_to_cmd() between
target_setup_cmd_from_cdb() and transport_handle_cdb_direct() logic.

It also includes adding a handful of new tcm_vhost_cmnd member +
assignments in vhost_scsi_allocate_cmd() used from cmwq process
context I/O submission within tcm_vhost_submission_work()

(v2: Use renamed target_submit_cmd_map_sgls)

Reported-by: Christoph Hellwig <hch@lst.de>
Cc: Christoph Hellwig <hch@lst.de>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Stefan Hajnoczi <stefanha@gmail.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

2 files changed, 22 insertions, 54 deletions

diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
index 89dc99baca80..aa31692064dd 100644
--- a/drivers/vhost/tcm_vhost.c
+++ b/drivers/vhost/tcm_vhost.c
@@ -415,10 +415,7 @@ static struct tcm_vhost_cmd *vhost_scsi_allocate_cmd(
 {
         struct tcm_vhost_cmd *tv_cmd;
         struct tcm_vhost_nexus *tv_nexus;
-        struct se_portal_group *se_tpg = &tv_tpg->se_tpg;
         struct se_session *se_sess;
-        struct se_cmd *se_cmd;
-        int sam_task_attr;
 
         tv_nexus = tv_tpg->tpg_nexus;
         if (!tv_nexus) {
@@ -434,23 +431,11 @@ static struct tcm_vhost_cmd *vhost_scsi_allocate_cmd(
         }
         INIT_LIST_HEAD(&tv_cmd->tvc_completion_list);
         tv_cmd->tvc_tag = v_req->tag;
+        tv_cmd->tvc_task_attr = v_req->task_attr;
+        tv_cmd->tvc_exp_data_len = exp_data_len;
+        tv_cmd->tvc_data_direction = data_direction;
+        tv_cmd->tvc_nexus = tv_nexus;
 
-        se_cmd = &tv_cmd->tvc_se_cmd;
-        /*
-         * Locate the SAM Task Attr from virtio_scsi_cmd_req
-         */
-        sam_task_attr = v_req->task_attr;
-        /*
-         * Initialize struct se_cmd descriptor from TCM infrastructure
-         */
-        transport_init_se_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess, exp_data_len,
-                                data_direction, sam_task_attr,
-                                &tv_cmd->tvc_sense_buf[0]);
-
-#if 0   /* FIXME: vhost_scsi_allocate_cmd() BIDI operation */
-        if (bidi)
-                se_cmd->se_cmd_flags |= SCF_BIDI;
-#endif
         return tv_cmd;
 }
 
@@ -549,37 +534,10 @@ static void tcm_vhost_submission_work(struct work_struct *work)
 {
         struct tcm_vhost_cmd *tv_cmd =
                 container_of(work, struct tcm_vhost_cmd, work);
+        struct tcm_vhost_nexus *tv_nexus;
         struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
         struct scatterlist *sg_ptr, *sg_bidi_ptr = NULL;
         int rc, sg_no_bidi = 0;
-        /*
-         * Locate the struct se_lun pointer based on v_req->lun, and
-         * attach it to struct se_cmd
-         */
-        rc = transport_lookup_cmd_lun(&tv_cmd->tvc_se_cmd, tv_cmd->tvc_lun);
-        if (rc < 0) {
-                pr_err("Failed to look up lun: %d\n", tv_cmd->tvc_lun);
-                transport_send_check_condition_and_sense(&tv_cmd->tvc_se_cmd,
-                        tv_cmd->tvc_se_cmd.scsi_sense_reason, 0);
-                transport_generic_free_cmd(se_cmd, 0);
-                return;
-        }
-
-        rc = target_setup_cmd_from_cdb(se_cmd, tv_cmd->tvc_cdb);
-        if (rc == -ENOMEM) {
-                transport_send_check_condition_and_sense(se_cmd,
-                                TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
-                transport_generic_free_cmd(se_cmd, 0);
-                return;
-        } else if (rc < 0) {
-                if (se_cmd->se_cmd_flags & SCF_SCSI_RESERVATION_CONFLICT)
-                        tcm_vhost_queue_status(se_cmd);
-                else
-                        transport_send_check_condition_and_sense(se_cmd,
-                                        se_cmd->scsi_sense_reason, 0);
-                transport_generic_free_cmd(se_cmd, 0);
-                return;
-        }
 
         if (tv_cmd->tvc_sgl_count) {
                 sg_ptr = tv_cmd->tvc_sgl;
@@ -597,17 +555,19 @@ static void tcm_vhost_submission_work(struct work_struct *work)
         } else {
                 sg_ptr = NULL;
         }
-
-        rc = transport_generic_map_mem_to_cmd(se_cmd, sg_ptr,
-                                tv_cmd->tvc_sgl_count, sg_bidi_ptr,
-                                sg_no_bidi);
+        tv_nexus = tv_cmd->tvc_nexus;
+
+        rc = target_submit_cmd_map_sgls(se_cmd, tv_nexus->tvn_se_sess,
+                        tv_cmd->tvc_cdb, &tv_cmd->tvc_sense_buf[0],
+                        tv_cmd->tvc_lun, tv_cmd->tvc_exp_data_len,
+                        tv_cmd->tvc_task_attr, tv_cmd->tvc_data_direction,
+                        0, sg_ptr, tv_cmd->tvc_sgl_count,
+                        sg_bidi_ptr, sg_no_bidi);
         if (rc < 0) {
                 transport_send_check_condition_and_sense(se_cmd,
-                                se_cmd->scsi_sense_reason, 0);
+                                TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
                 transport_generic_free_cmd(se_cmd, 0);
-                return;
         }
-        transport_handle_cdb_direct(se_cmd);
 }
 
 static void vhost_scsi_handle_vq(struct vhost_scsi *vs)
diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h
index d9e93557d669..7e87c63ecbcd 100644
--- a/drivers/vhost/tcm_vhost.h
+++ b/drivers/vhost/tcm_vhost.h
@@ -5,6 +5,12 @@
 struct tcm_vhost_cmd {
         /* Descriptor from vhost_get_vq_desc() for virt_queue segment */
         int tvc_vq_desc;
+        /* virtio-scsi initiator task attribute */
+        int tvc_task_attr;
+        /* virtio-scsi initiator data direction */
+        enum dma_data_direction tvc_data_direction;
+        /* Expected data transfer length from virtio-scsi header */
+        u32 tvc_exp_data_len;
         /* The Tag from include/linux/virtio_scsi.h:struct virtio_scsi_cmd_req */
         u64 tvc_tag;
         /* The number of scatterlists associated with this cmd */
@@ -17,6 +23,8 @@ struct tcm_vhost_cmd {
         struct virtio_scsi_cmd_resp __user *tvc_resp;
         /* Pointer to vhost_scsi for our device */
         struct vhost_scsi *tvc_vhost;
+        /* Pointer to vhost nexus memory */
+        struct tcm_vhost_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 tcm_vhost_submission_work() */