ib_srpt: Convert I/O path to target_submit_cmd + drop legacy ioctx->kref

This patch converts the main srpt_handle_cmd() I/O path to use modern
target_submit_cmd() with TARGET_SCF_ACK_KREF flag usage.  This includes
dropping the original internal ioctx->kref + srpt_put_send_ioctx() usage
in favor of target_put_sess_cmd() w/ se_cmd_t->cmd_kref within ib_srpt
response callbacks.

It also updates srpt_abort_cmd() to call target_put_sess_cmd() for
completion of aborted commands, and adds target_wait_for_sess_cmds() into
srpt_release_channel_work() to allow outstanding I/O to complete during
session shutdown.

Also, go ahead and update srpt_handle_tsk_mgmt() to make the remaining
transport_init_se_cmd() to setup the ioctx->cmd with se_tmr_req.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Roland Dreier <roland@kernel.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

2 files changed, 52 insertions, 71 deletions

diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c b/drivers/infiniband/ulp/srpt/ib_srpt.c
index e6fafc62acae..77b6368fec3d 100644
--- a/drivers/infiniband/ulp/srpt/ib_srpt.c
+++ b/drivers/infiniband/ulp/srpt/ib_srpt.c
@@ -1269,7 +1269,6 @@ static struct srpt_send_ioctx *srpt_get_send_ioctx(struct srpt_rdma_ch *ch)
                 return ioctx;
 
         BUG_ON(ioctx->ch != ch);
-        kref_init(&ioctx->kref);
         spin_lock_init(&ioctx->spinlock);
         ioctx->state = SRPT_STATE_NEW;
         ioctx->n_rbuf = 0;
@@ -1291,39 +1290,6 @@ static struct srpt_send_ioctx *srpt_get_send_ioctx(struct srpt_rdma_ch *ch)
 }
 
 /**
- * srpt_put_send_ioctx() - Free up resources.
- */
-static void srpt_put_send_ioctx(struct srpt_send_ioctx *ioctx)
-{
-        struct srpt_rdma_ch *ch;
-        unsigned long flags;
-
-        BUG_ON(!ioctx);
-        ch = ioctx->ch;
-        BUG_ON(!ch);
-
-        WARN_ON(srpt_get_cmd_state(ioctx) != SRPT_STATE_DONE);
-
-        srpt_unmap_sg_to_ib_sge(ioctx->ch, ioctx);
-        transport_generic_free_cmd(&ioctx->cmd, 0);
-
-        if (ioctx->n_rbuf > 1) {
-                kfree(ioctx->rbufs);
-                ioctx->rbufs = NULL;
-                ioctx->n_rbuf = 0;
-        }
-
-        spin_lock_irqsave(&ch->spinlock, flags);
-        list_add(&ioctx->free_list, &ch->free_list);
-        spin_unlock_irqrestore(&ch->spinlock, flags);
-}
-
-static void srpt_put_send_ioctx_kref(struct kref *kref)
-{
-        srpt_put_send_ioctx(container_of(kref, struct srpt_send_ioctx, kref));
-}
-
-/**
  * srpt_abort_cmd() - Abort a SCSI command.
  * @ioctx:   I/O context associated with the SCSI command.
  * @context: Preferred execution context.
@@ -1359,8 +1325,14 @@ static int srpt_abort_cmd(struct srpt_send_ioctx *ioctx)
         }
         spin_unlock_irqrestore(&ioctx->spinlock, flags);
 
-        if (state == SRPT_STATE_DONE)
+        if (state == SRPT_STATE_DONE) {
+                struct srpt_rdma_ch *ch = ioctx->ch;
+
+                BUG_ON(ch->sess == NULL);
+
+                target_put_sess_cmd(ch->sess, &ioctx->cmd);
                 goto out;
+        }
 
         pr_debug("Aborting cmd with state %d and tag %lld\n", state,
                  ioctx->tag);
@@ -1395,11 +1367,11 @@ static int srpt_abort_cmd(struct srpt_send_ioctx *ioctx)
                 spin_lock_irqsave(&ioctx->cmd.t_state_lock, flags);
                 ioctx->cmd.transport_state |= CMD_T_LUN_STOP;
                 spin_unlock_irqrestore(&ioctx->cmd.t_state_lock, flags);
-                kref_put(&ioctx->kref, srpt_put_send_ioctx_kref);
+                target_put_sess_cmd(ioctx->ch->sess, &ioctx->cmd);
                 break;
         case SRPT_STATE_MGMT_RSP_SENT:
                 srpt_set_cmd_state(ioctx, SRPT_STATE_DONE);
-                kref_put(&ioctx->kref, srpt_put_send_ioctx_kref);
+                target_put_sess_cmd(ioctx->ch->sess, &ioctx->cmd);
                 break;
         default:
                 WARN_ON("ERROR: unexpected command state");
@@ -1457,11 +1429,13 @@ static void srpt_handle_send_comp(struct srpt_rdma_ch *ch,
                     && state != SRPT_STATE_DONE))
                 pr_debug("state = %d\n", state);
 
-        if (state != SRPT_STATE_DONE)
-                kref_put(&ioctx->kref, srpt_put_send_ioctx_kref);
-        else
+        if (state != SRPT_STATE_DONE) {
+                srpt_unmap_sg_to_ib_sge(ch, ioctx);
+                transport_generic_free_cmd(&ioctx->cmd, 0);
+        } else {
                 printk(KERN_ERR "IB completion has been received too late for"
                        " wr_id = %u.\n", ioctx->ioctx.index);
+        }
 }
 
 /**
@@ -1712,10 +1686,10 @@ out_err:
 
 static int srpt_check_stop_free(struct se_cmd *cmd)
 {
-        struct srpt_send_ioctx *ioctx;
+        struct srpt_send_ioctx *ioctx = container_of(cmd,
+                                struct srpt_send_ioctx, cmd);
 
-        ioctx = container_of(cmd, struct srpt_send_ioctx, cmd);
-        return kref_put(&ioctx->kref, srpt_put_send_ioctx_kref);
+        return target_put_sess_cmd(ioctx->ch->sess, &ioctx->cmd);
 }
 
 /**
@@ -1731,11 +1705,11 @@ static int srpt_handle_cmd(struct srpt_rdma_ch *ch,
         u64 data_len;
         enum dma_data_direction dir;
         sense_reason_t ret;
+        int rc;
 
         BUG_ON(!send_ioctx);
 
         srp_cmd = recv_ioctx->ioctx.buf;
-        kref_get(&send_ioctx->kref);
         cmd = &send_ioctx->cmd;
         send_ioctx->tag = srp_cmd->tag;
 
@@ -1759,30 +1733,18 @@ static int srpt_handle_cmd(struct srpt_rdma_ch *ch,
                 printk(KERN_ERR "0x%llx: parsing SRP descriptor table failed.\n",
                        srp_cmd->tag);
                 ret = TCM_INVALID_CDB_FIELD;
-                kref_put(&send_ioctx->kref, srpt_put_send_ioctx_kref);
                 goto send_sense;
         }
 
-        cmd->data_length = data_len;
-        cmd->data_direction = dir;
         unpacked_lun = srpt_unpack_lun((uint8_t *)&srp_cmd->lun,
                                        sizeof(srp_cmd->lun));
-        ret = transport_lookup_cmd_lun(cmd, unpacked_lun);
-        if (ret) {
-                kref_put(&send_ioctx->kref, srpt_put_send_ioctx_kref);
+        rc = target_submit_cmd(cmd, ch->sess, srp_cmd->cdb,
+                        &send_ioctx->sense_data[0], unpacked_lun, data_len,
+                        MSG_SIMPLE_TAG, dir, TARGET_SCF_ACK_KREF);
+        if (rc != 0) {
+                ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
                 goto send_sense;
         }
-        ret = target_setup_cmd_from_cdb(cmd, srp_cmd->cdb);
-        if (ret) {
-                kref_put(&send_ioctx->kref, srpt_put_send_ioctx_kref);
-                if (ret == TCM_RESERVATION_CONFLICT) {
-                        srpt_queue_status(cmd);
-                        return 0;
-                }
-                goto send_sense;
-        }
-
-        transport_handle_cdb_direct(cmd);
         return 0;
 
 send_sense:
@@ -1884,6 +1846,9 @@ static void srpt_handle_tsk_mgmt(struct srpt_rdma_ch *ch,
                         TMR_TASK_MGMT_FUNCTION_NOT_SUPPORTED;
                 goto fail;
         }
+        transport_init_se_cmd(&send_ioctx->cmd, &srpt_target->tf_ops, ch->sess,
+                        0, DMA_NONE, MSG_SIMPLE_TAG, send_ioctx->sense_data);
+
         res = core_tmr_alloc_req(cmd, NULL, tcm_tmr, GFP_KERNEL);
         if (res < 0) {
                 send_ioctx->cmd.se_tmr_req->response = TMR_FUNCTION_REJECTED;
@@ -1902,11 +1867,9 @@ static void srpt_handle_tsk_mgmt(struct srpt_rdma_ch *ch,
         if (srp_tsk->tsk_mgmt_func == SRP_TSK_ABORT_TASK)
                 srpt_rx_mgmt_fn_tag(send_ioctx, srp_tsk->task_tag);
 
-        kref_get(&send_ioctx->kref);
         transport_generic_handle_tmr(&send_ioctx->cmd);
         return;
 fail:
-        kref_get(&send_ioctx->kref);
         transport_send_check_condition_and_sense(cmd, 0, 0); // XXX:
 }
 
@@ -1949,10 +1912,6 @@ static void srpt_handle_new_iu(struct srpt_rdma_ch *ch,
                 }
         }
 
-        transport_init_se_cmd(&send_ioctx->cmd, &srpt_target->tf_ops, ch->sess,
-                              0, DMA_NONE, MSG_SIMPLE_TAG,
-                              send_ioctx->sense_data);
-
         switch (srp_cmd->opcode) {
         case SRP_CMD:
                 srpt_handle_cmd(ch, recv_ioctx, send_ioctx);
@@ -2358,6 +2317,7 @@ static void srpt_release_channel_work(struct work_struct *w)
 {
         struct srpt_rdma_ch *ch;
         struct srpt_device *sdev;
+        struct se_session *se_sess;
 
         ch = container_of(w, struct srpt_rdma_ch, release_work);
         pr_debug("ch = %p; ch->sess = %p; release_done = %p\n", ch, ch->sess,
@@ -2366,8 +2326,13 @@ static void srpt_release_channel_work(struct work_struct *w)
         sdev = ch->sport->sdev;
         BUG_ON(!sdev);
 
-        transport_deregister_session_configfs(ch->sess);
-        transport_deregister_session(ch->sess);
+        se_sess = ch->sess;
+        BUG_ON(!se_sess);
+
+        target_wait_for_sess_cmds(se_sess, 0);
+
+        transport_deregister_session_configfs(se_sess);
+        transport_deregister_session(se_sess);
         ch->sess = NULL;
 
         srpt_destroy_ch_ib(ch);
@@ -3092,7 +3057,7 @@ static int srpt_queue_response(struct se_cmd *cmd)
                        ioctx->tag);
                 srpt_unmap_sg_to_ib_sge(ch, ioctx);
                 srpt_set_cmd_state(ioctx, SRPT_STATE_DONE);
-                kref_put(&ioctx->kref, srpt_put_send_ioctx_kref);
+                target_put_sess_cmd(ioctx->ch->sess, &ioctx->cmd);
         }
 
 out:
@@ -3483,6 +3448,23 @@ static u32 srpt_tpg_get_inst_index(struct se_portal_group *se_tpg)
 
 static void srpt_release_cmd(struct se_cmd *se_cmd)
 {
+        struct srpt_send_ioctx *ioctx = container_of(se_cmd,
+                                struct srpt_send_ioctx, cmd);
+        struct srpt_rdma_ch *ch = ioctx->ch;
+        unsigned long flags;
+
+        WARN_ON(ioctx->state != SRPT_STATE_DONE);
+        WARN_ON(ioctx->mapped_sg_count != 0);
+
+        if (ioctx->n_rbuf > 1) {
+                kfree(ioctx->rbufs);
+                ioctx->rbufs = NULL;
+                ioctx->n_rbuf = 0;
+        }
+
+        spin_lock_irqsave(&ch->spinlock, flags);
+        list_add(&ioctx->free_list, &ch->free_list);
+        spin_unlock_irqrestore(&ch->spinlock, flags);
 }
 
 /**
diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.h b/drivers/infiniband/ulp/srpt/ib_srpt.h
index 61e52b830816..4caf55cda7b1 100644
--- a/drivers/infiniband/ulp/srpt/ib_srpt.h
+++ b/drivers/infiniband/ulp/srpt/ib_srpt.h
@@ -228,7 +228,6 @@ struct srpt_recv_ioctx {
 struct srpt_send_ioctx {
         struct srpt_ioctx       ioctx;
         struct srpt_rdma_ch     *ch;
-        struct kref              kref;
         struct rdma_iu          *rdma_ius;
         struct srp_direct_buf   *rbufs;
         struct srp_direct_buf   single_rbuf;