Merge branch 'nvme-4.13' of git://git.infradead.org/nvme into for-linus

Pull NVMe fixes from Christoph:

"A few more small fixes - the fc/lpfc update is the biggest by far."

8 files changed, 261 insertions, 51 deletions

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index c49f1f8b2e57..37046ac2c441 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -336,7 +336,7 @@ static int nvme_get_stream_params(struct nvme_ctrl *ctrl,
 
         c.directive.opcode = nvme_admin_directive_recv;
         c.directive.nsid = cpu_to_le32(nsid);
-        c.directive.numd = cpu_to_le32(sizeof(*s));
+        c.directive.numd = cpu_to_le32((sizeof(*s) >> 2) - 1);
         c.directive.doper = NVME_DIR_RCV_ST_OP_PARAM;
         c.directive.dtype = NVME_DIR_STREAMS;
 
@@ -1509,7 +1509,7 @@ static void nvme_set_queue_limits(struct nvme_ctrl *ctrl,
         blk_queue_write_cache(q, vwc, vwc);
 }
 
-static void nvme_configure_apst(struct nvme_ctrl *ctrl)
+static int nvme_configure_apst(struct nvme_ctrl *ctrl)
 {
         /*
          * APST (Autonomous Power State Transition) lets us program a
@@ -1538,16 +1538,16 @@ static void nvme_configure_apst(struct nvme_ctrl *ctrl)
          * then don't do anything.
          */
         if (!ctrl->apsta)
-                return;
+                return 0;
 
         if (ctrl->npss > 31) {
                 dev_warn(ctrl->device, "NPSS is invalid; not using APST\n");
-                return;
+                return 0;
         }
 
         table = kzalloc(sizeof(*table), GFP_KERNEL);
         if (!table)
-                return;
+                return 0;
 
         if (!ctrl->apst_enabled || ctrl->ps_max_latency_us == 0) {
                 /* Turn off APST. */
@@ -1629,6 +1629,7 @@ static void nvme_configure_apst(struct nvme_ctrl *ctrl)
                 dev_err(ctrl->device, "failed to set APST feature (%d)\n", ret);
 
         kfree(table);
+        return ret;
 }
 
 static void nvme_set_latency_tolerance(struct device *dev, s32 val)
@@ -1835,13 +1836,16 @@ int nvme_init_identify(struct nvme_ctrl *ctrl)
                  * In fabrics we need to verify the cntlid matches the
                  * admin connect
                  */
-                if (ctrl->cntlid != le16_to_cpu(id->cntlid))
+                if (ctrl->cntlid != le16_to_cpu(id->cntlid)) {
                         ret = -EINVAL;
+                        goto out_free;
+                }
 
                 if (!ctrl->opts->discovery_nqn && !ctrl->kas) {
                         dev_err(ctrl->device,
                                 "keep-alive support is mandatory for fabrics\n");
                         ret = -EINVAL;
+                        goto out_free;
                 }
         } else {
                 ctrl->cntlid = le16_to_cpu(id->cntlid);
@@ -1856,11 +1860,20 @@ int nvme_init_identify(struct nvme_ctrl *ctrl)
         else if (!ctrl->apst_enabled && prev_apst_enabled)
                 dev_pm_qos_hide_latency_tolerance(ctrl->device);
 
-        nvme_configure_apst(ctrl);
-        nvme_configure_directives(ctrl);
+        ret = nvme_configure_apst(ctrl);
+        if (ret < 0)
+                return ret;
+
+        ret = nvme_configure_directives(ctrl);
+        if (ret < 0)
+                return ret;
 
         ctrl->identified = true;
 
+        return 0;
+
+out_free:
+        kfree(id);
         return ret;
 }
 EXPORT_SYMBOL_GPL(nvme_init_identify);
@@ -2004,9 +2017,11 @@ static ssize_t wwid_show(struct device *dev, struct device_attribute *attr,
         if (memchr_inv(ns->eui, 0, sizeof(ns->eui)))
                 return sprintf(buf, "eui.%8phN\n", ns->eui);
 
-        while (ctrl->serial[serial_len - 1] == ' ')
+        while (serial_len > 0 && (ctrl->serial[serial_len - 1] == ' ' ||
+                                  ctrl->serial[serial_len - 1] == '\0'))
                 serial_len--;
-        while (ctrl->model[model_len - 1] == ' ')
+        while (model_len > 0 && (ctrl->model[model_len - 1] == ' ' ||
+                                 ctrl->model[model_len - 1] == '\0'))
                 model_len--;
 
         return sprintf(buf, "nvme.%04x-%*phN-%*phN-%08x\n", ctrl->vid,
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index cd888a47d0fc..74a124a06264 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1558,11 +1558,9 @@ static inline void nvme_release_cmb(struct nvme_dev *dev)
         if (dev->cmb) {
                 iounmap(dev->cmb);
                 dev->cmb = NULL;
-                if (dev->cmbsz) {
-                        sysfs_remove_file_from_group(&dev->ctrl.device->kobj,
-                                                     &dev_attr_cmb.attr, NULL);
-                        dev->cmbsz = 0;
-                }
+                sysfs_remove_file_from_group(&dev->ctrl.device->kobj,
+                                             &dev_attr_cmb.attr, NULL);
+                dev->cmbsz = 0;
         }
 }
 
@@ -1953,16 +1951,14 @@ static int nvme_pci_enable(struct nvme_dev *dev)
 
         /*
          * CMBs can currently only exist on >=1.2 PCIe devices. We only
-         * populate sysfs if a CMB is implemented. Note that we add the
-         * CMB attribute to the nvme_ctrl kobj which removes the need to remove
-         * it on exit. Since nvme_dev_attrs_group has no name we can pass
-         * NULL as final argument to sysfs_add_file_to_group.
+         * populate sysfs if a CMB is implemented. Since nvme_dev_attrs_group
+         * has no name we can pass NULL as final argument to
+         * sysfs_add_file_to_group.
          */
 
         if (readl(dev->bar + NVME_REG_VS) >= NVME_VS(1, 2, 0)) {
                 dev->cmb = nvme_map_cmb(dev);
-
-                if (dev->cmbsz) {
+                if (dev->cmb) {
                         if (sysfs_add_file_to_group(&dev->ctrl.device->kobj,
                                                     &dev_attr_cmb.attr, NULL))
                                 dev_warn(dev->ctrl.device,
diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c
index 31ca55dfcb1d..1b7f2520a20d 100644
--- a/drivers/nvme/target/fc.c
+++ b/drivers/nvme/target/fc.c
@@ -114,6 +114,11 @@ struct nvmet_fc_tgtport {
         struct kref                     ref;
 };
 
+struct nvmet_fc_defer_fcp_req {
+        struct list_head                req_list;
+        struct nvmefc_tgt_fcp_req       *fcp_req;
+};
+
 struct nvmet_fc_tgt_queue {
         bool                            ninetypercent;
         u16                             qid;
@@ -132,6 +137,8 @@ struct nvmet_fc_tgt_queue {
         struct nvmet_fc_tgt_assoc       *assoc;
         struct nvmet_fc_fcp_iod         *fod;           /* array of fcp_iods */
         struct list_head                fod_list;
+        struct list_head                pending_cmd_list;
+        struct list_head                avail_defer_list;
         struct workqueue_struct         *work_q;
         struct kref                     ref;
 } __aligned(sizeof(unsigned long long));
@@ -223,6 +230,8 @@ static void nvmet_fc_tgt_q_put(struct nvmet_fc_tgt_queue *queue);
 static int nvmet_fc_tgt_q_get(struct nvmet_fc_tgt_queue *queue);
 static void nvmet_fc_tgtport_put(struct nvmet_fc_tgtport *tgtport);
 static int nvmet_fc_tgtport_get(struct nvmet_fc_tgtport *tgtport);
+static void nvmet_fc_handle_fcp_rqst(struct nvmet_fc_tgtport *tgtport,
+                                        struct nvmet_fc_fcp_iod *fod);
 
 
 /* *********************** FC-NVME DMA Handling **************************** */
@@ -463,9 +472,9 @@ static struct nvmet_fc_fcp_iod *
 nvmet_fc_alloc_fcp_iod(struct nvmet_fc_tgt_queue *queue)
 {
         static struct nvmet_fc_fcp_iod *fod;
-        unsigned long flags;
 
-        spin_lock_irqsave(&queue->qlock, flags);
+        lockdep_assert_held(&queue->qlock);
+
         fod = list_first_entry_or_null(&queue->fod_list,
                                         struct nvmet_fc_fcp_iod, fcp_list);
         if (fod) {
@@ -477,17 +486,37 @@ nvmet_fc_alloc_fcp_iod(struct nvmet_fc_tgt_queue *queue)
                  * will "inherit" that reference.
                  */
         }
-        spin_unlock_irqrestore(&queue->qlock, flags);
         return fod;
 }
 
 
 static void
+nvmet_fc_queue_fcp_req(struct nvmet_fc_tgtport *tgtport,
+                       struct nvmet_fc_tgt_queue *queue,
+                       struct nvmefc_tgt_fcp_req *fcpreq)
+{
+        struct nvmet_fc_fcp_iod *fod = fcpreq->nvmet_fc_private;
+
+        /*
+         * put all admin cmds on hw queue id 0. All io commands go to
+         * the respective hw queue based on a modulo basis
+         */
+        fcpreq->hwqid = queue->qid ?
+                        ((queue->qid - 1) % tgtport->ops->max_hw_queues) : 0;
+
+        if (tgtport->ops->target_features & NVMET_FCTGTFEAT_CMD_IN_ISR)
+                queue_work_on(queue->cpu, queue->work_q, &fod->work);
+        else
+                nvmet_fc_handle_fcp_rqst(tgtport, fod);
+}
+
+static void
 nvmet_fc_free_fcp_iod(struct nvmet_fc_tgt_queue *queue,
                         struct nvmet_fc_fcp_iod *fod)
 {
         struct nvmefc_tgt_fcp_req *fcpreq = fod->fcpreq;
         struct nvmet_fc_tgtport *tgtport = fod->tgtport;
+        struct nvmet_fc_defer_fcp_req *deferfcp;
         unsigned long flags;
 
         fc_dma_sync_single_for_cpu(tgtport->dev, fod->rspdma,
@@ -495,21 +524,56 @@ nvmet_fc_free_fcp_iod(struct nvmet_fc_tgt_queue *queue,
 
         fcpreq->nvmet_fc_private = NULL;
 
-        spin_lock_irqsave(&queue->qlock, flags);
-        list_add_tail(&fod->fcp_list, &fod->queue->fod_list);
         fod->active = false;
         fod->abort = false;
         fod->aborted = false;
         fod->writedataactive = false;
         fod->fcpreq = NULL;
+
+        tgtport->ops->fcp_req_release(&tgtport->fc_target_port, fcpreq);
+
+        spin_lock_irqsave(&queue->qlock, flags);
+        deferfcp = list_first_entry_or_null(&queue->pending_cmd_list,
+                                struct nvmet_fc_defer_fcp_req, req_list);
+        if (!deferfcp) {
+                list_add_tail(&fod->fcp_list, &fod->queue->fod_list);
+                spin_unlock_irqrestore(&queue->qlock, flags);
+
+                /* Release reference taken at queue lookup and fod allocation */
+                nvmet_fc_tgt_q_put(queue);
+                return;
+        }
+
+        /* Re-use the fod for the next pending cmd that was deferred */
+        list_del(&deferfcp->req_list);
+
+        fcpreq = deferfcp->fcp_req;
+
+        /* deferfcp can be reused for another IO at a later date */
+        list_add_tail(&deferfcp->req_list, &queue->avail_defer_list);
+
         spin_unlock_irqrestore(&queue->qlock, flags);
 
+        /* Save NVME CMD IO in fod */
+        memcpy(&fod->cmdiubuf, fcpreq->rspaddr, fcpreq->rsplen);
+
+        /* Setup new fcpreq to be processed */
+        fcpreq->rspaddr = NULL;
+        fcpreq->rsplen  = 0;
+        fcpreq->nvmet_fc_private = fod;
+        fod->fcpreq = fcpreq;
+        fod->active = true;
+
+        /* inform LLDD IO is now being processed */
+        tgtport->ops->defer_rcv(&tgtport->fc_target_port, fcpreq);
+
+        /* Submit deferred IO for processing */
+        nvmet_fc_queue_fcp_req(tgtport, queue, fcpreq);
+
         /*
-         * release the reference taken at queue lookup and fod allocation
+         * Leave the queue lookup get reference taken when
+         * fod was originally allocated.
          */
-        nvmet_fc_tgt_q_put(queue);
-
-        tgtport->ops->fcp_req_release(&tgtport->fc_target_port, fcpreq);
 }
 
 static int
@@ -569,6 +633,8 @@ nvmet_fc_alloc_target_queue(struct nvmet_fc_tgt_assoc *assoc,
         queue->port = assoc->tgtport->port;
         queue->cpu = nvmet_fc_queue_to_cpu(assoc->tgtport, qid);
         INIT_LIST_HEAD(&queue->fod_list);
+        INIT_LIST_HEAD(&queue->avail_defer_list);
+        INIT_LIST_HEAD(&queue->pending_cmd_list);
         atomic_set(&queue->connected, 0);
         atomic_set(&queue->sqtail, 0);
         atomic_set(&queue->rsn, 1);
@@ -638,6 +704,7 @@ nvmet_fc_delete_target_queue(struct nvmet_fc_tgt_queue *queue)
 {
         struct nvmet_fc_tgtport *tgtport = queue->assoc->tgtport;
         struct nvmet_fc_fcp_iod *fod = queue->fod;
+        struct nvmet_fc_defer_fcp_req *deferfcp;
         unsigned long flags;
         int i, writedataactive;
         bool disconnect;
@@ -666,6 +733,35 @@ nvmet_fc_delete_target_queue(struct nvmet_fc_tgt_queue *queue)
                         }
                 }
         }
+
+        /* Cleanup defer'ed IOs in queue */
+        list_for_each_entry(deferfcp, &queue->avail_defer_list, req_list) {
+                list_del(&deferfcp->req_list);
+                kfree(deferfcp);
+        }
+
+        for (;;) {
+                deferfcp = list_first_entry_or_null(&queue->pending_cmd_list,
+                                struct nvmet_fc_defer_fcp_req, req_list);
+                if (!deferfcp)
+                        break;
+
+                list_del(&deferfcp->req_list);
+                spin_unlock_irqrestore(&queue->qlock, flags);
+
+                tgtport->ops->defer_rcv(&tgtport->fc_target_port,
+                                deferfcp->fcp_req);
+
+                tgtport->ops->fcp_abort(&tgtport->fc_target_port,
+                                deferfcp->fcp_req);
+
+                tgtport->ops->fcp_req_release(&tgtport->fc_target_port,
+                                deferfcp->fcp_req);
+
+                kfree(deferfcp);
+
+                spin_lock_irqsave(&queue->qlock, flags);
+        }
         spin_unlock_irqrestore(&queue->qlock, flags);
 
         flush_workqueue(queue->work_q);
@@ -2172,11 +2268,38 @@ nvmet_fc_handle_fcp_rqst_work(struct work_struct *work)
  * Pass a FC-NVME FCP CMD IU received from the FC link to the nvmet-fc
  * layer for processing.
  *
- * The nvmet-fc layer will copy cmd payload to an internal structure for
- * processing.  As such, upon completion of the routine, the LLDD may
- * immediately free/reuse the CMD IU buffer passed in the call.
+ * The nvmet_fc layer allocates a local job structure (struct
+ * nvmet_fc_fcp_iod) from the queue for the io and copies the
+ * CMD IU buffer to the job structure. As such, on a successful
+ * completion (returns 0), the LLDD may immediately free/reuse
+ * the CMD IU buffer passed in the call.
+ *
+ * However, in some circumstances, due to the packetized nature of FC
+ * and the api of the FC LLDD which may issue a hw command to send the
+ * response, but the LLDD may not get the hw completion for that command
+ * and upcall the nvmet_fc layer before a new command may be
+ * asynchronously received - its possible for a command to be received
+ * before the LLDD and nvmet_fc have recycled the job structure. It gives
+ * the appearance of more commands received than fits in the sq.
+ * To alleviate this scenario, a temporary queue is maintained in the
+ * transport for pending LLDD requests waiting for a queue job structure.
+ * In these "overrun" cases, a temporary queue element is allocated
+ * the LLDD request and CMD iu buffer information remembered, and the
+ * routine returns a -EOVERFLOW status. Subsequently, when a queue job
+ * structure is freed, it is immediately reallocated for anything on the
+ * pending request list. The LLDDs defer_rcv() callback is called,
+ * informing the LLDD that it may reuse the CMD IU buffer, and the io
+ * is then started normally with the transport.
  *
- * If this routine returns error, the lldd should abort the exchange.
+ * The LLDD, when receiving an -EOVERFLOW completion status, is to treat
+ * the completion as successful but must not reuse the CMD IU buffer
+ * until the LLDD's defer_rcv() callback has been called for the
+ * corresponding struct nvmefc_tgt_fcp_req pointer.
+ *
+ * If there is any other condition in which an error occurs, the
+ * transport will return a non-zero status indicating the error.
+ * In all cases other than -EOVERFLOW, the transport has not accepted the
+ * request and the LLDD should abort the exchange.
  *
  * @target_port: pointer to the (registered) target port the FCP CMD IU
  *              was received on.
@@ -2194,6 +2317,8 @@ nvmet_fc_rcv_fcp_req(struct nvmet_fc_target_port *target_port,
         struct nvme_fc_cmd_iu *cmdiu = cmdiubuf;
         struct nvmet_fc_tgt_queue *queue;
         struct nvmet_fc_fcp_iod *fod;
+        struct nvmet_fc_defer_fcp_req *deferfcp;
+        unsigned long flags;
 
         /* validate iu, so the connection id can be used to find the queue */
         if ((cmdiubuf_len != sizeof(*cmdiu)) ||
@@ -2214,29 +2339,60 @@ nvmet_fc_rcv_fcp_req(struct nvmet_fc_target_port *target_port,
          * when the fod is freed.
          */
 
+        spin_lock_irqsave(&queue->qlock, flags);
+
         fod = nvmet_fc_alloc_fcp_iod(queue);
-        if (!fod) {
+        if (fod) {
+                spin_unlock_irqrestore(&queue->qlock, flags);
+
+                fcpreq->nvmet_fc_private = fod;
+                fod->fcpreq = fcpreq;
+
+                memcpy(&fod->cmdiubuf, cmdiubuf, cmdiubuf_len);
+
+                nvmet_fc_queue_fcp_req(tgtport, queue, fcpreq);
+
+                return 0;
+        }
+
+        if (!tgtport->ops->defer_rcv) {
+                spin_unlock_irqrestore(&queue->qlock, flags);
                 /* release the queue lookup reference */
                 nvmet_fc_tgt_q_put(queue);
                 return -ENOENT;
         }
 
-        fcpreq->nvmet_fc_private = fod;
-        fod->fcpreq = fcpreq;
-        /*
-         * put all admin cmds on hw queue id 0. All io commands go to
-         * the respective hw queue based on a modulo basis
-         */
-        fcpreq->hwqid = queue->qid ?
-                        ((queue->qid - 1) % tgtport->ops->max_hw_queues) : 0;
-        memcpy(&fod->cmdiubuf, cmdiubuf, cmdiubuf_len);
+        deferfcp = list_first_entry_or_null(&queue->avail_defer_list,
+                        struct nvmet_fc_defer_fcp_req, req_list);
+        if (deferfcp) {
+                /* Just re-use one that was previously allocated */
+                list_del(&deferfcp->req_list);
+        } else {
+                spin_unlock_irqrestore(&queue->qlock, flags);
 
-        if (tgtport->ops->target_features & NVMET_FCTGTFEAT_CMD_IN_ISR)
-                queue_work_on(queue->cpu, queue->work_q, &fod->work);
-        else
-                nvmet_fc_handle_fcp_rqst(tgtport, fod);
+                /* Now we need to dynamically allocate one */
+                deferfcp = kmalloc(sizeof(*deferfcp), GFP_KERNEL);
+                if (!deferfcp) {
+                        /* release the queue lookup reference */
+                        nvmet_fc_tgt_q_put(queue);
+                        return -ENOMEM;
+                }
+                spin_lock_irqsave(&queue->qlock, flags);
+        }
 
-        return 0;
+        /* For now, use rspaddr / rsplen to save payload information */
+        fcpreq->rspaddr = cmdiubuf;
+        fcpreq->rsplen  = cmdiubuf_len;
+        deferfcp->fcp_req = fcpreq;
+
+        /* defer processing till a fod becomes available */
+        list_add_tail(&deferfcp->req_list, &queue->pending_cmd_list);
+
+        /* NOTE: the queue lookup reference is still valid */
+
+        spin_unlock_irqrestore(&queue->qlock, flags);
+
+        return -EOVERFLOW;
 }
 EXPORT_SYMBOL_GPL(nvmet_fc_rcv_fcp_req);
 
diff --git a/drivers/scsi/lpfc/lpfc_attr.c b/drivers/scsi/lpfc/lpfc_attr.c
index 4ed48ed38e79..7ee1a94c0b33 100644
--- a/drivers/scsi/lpfc/lpfc_attr.c
+++ b/drivers/scsi/lpfc/lpfc_attr.c
@@ -205,8 +205,10 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
                                 atomic_read(&tgtp->xmt_ls_rsp_error));
 
                 len += snprintf(buf+len, PAGE_SIZE-len,
-                                "FCP: Rcv %08x Release %08x Drop %08x\n",
+                                "FCP: Rcv %08x Defer %08x Release %08x "
+                                "Drop %08x\n",
                                 atomic_read(&tgtp->rcv_fcp_cmd_in),
+                                atomic_read(&tgtp->rcv_fcp_cmd_defer),
                                 atomic_read(&tgtp->xmt_fcp_release),
                                 atomic_read(&tgtp->rcv_fcp_cmd_drop));
 
diff --git a/drivers/scsi/lpfc/lpfc_debugfs.c b/drivers/scsi/lpfc/lpfc_debugfs.c
index 5cc8b0f7d885..744f3f395b64 100644
--- a/drivers/scsi/lpfc/lpfc_debugfs.c
+++ b/drivers/scsi/lpfc/lpfc_debugfs.c
@@ -782,8 +782,11 @@ lpfc_debugfs_nvmestat_data(struct lpfc_vport *vport, char *buf, int size)
                                 atomic_read(&tgtp->xmt_ls_rsp_error));
 
                 len += snprintf(buf + len, size - len,
-                                "FCP: Rcv %08x Drop %08x\n",
+                                "FCP: Rcv %08x Defer %08x Release %08x "
+                                "Drop %08x\n",
                                 atomic_read(&tgtp->rcv_fcp_cmd_in),
+                                atomic_read(&tgtp->rcv_fcp_cmd_defer),
+                                atomic_read(&tgtp->xmt_fcp_release),
                                 atomic_read(&tgtp->rcv_fcp_cmd_drop));
 
                 if (atomic_read(&tgtp->rcv_fcp_cmd_in) !=
diff --git a/drivers/scsi/lpfc/lpfc_nvmet.c b/drivers/scsi/lpfc/lpfc_nvmet.c
index fbeec344c6cc..bbbd0f84160d 100644
--- a/drivers/scsi/lpfc/lpfc_nvmet.c
+++ b/drivers/scsi/lpfc/lpfc_nvmet.c
@@ -841,12 +841,31 @@ lpfc_nvmet_xmt_fcp_release(struct nvmet_fc_target_port *tgtport,
         lpfc_nvmet_ctxbuf_post(phba, ctxp->ctxbuf);
 }
 
+static void
+lpfc_nvmet_defer_rcv(struct nvmet_fc_target_port *tgtport,
+                     struct nvmefc_tgt_fcp_req *rsp)
+{
+        struct lpfc_nvmet_tgtport *tgtp;
+        struct lpfc_nvmet_rcv_ctx *ctxp =
+                container_of(rsp, struct lpfc_nvmet_rcv_ctx, ctx.fcp_req);
+        struct rqb_dmabuf *nvmebuf = ctxp->rqb_buffer;
+        struct lpfc_hba *phba = ctxp->phba;
+
+        lpfc_nvmeio_data(phba, "NVMET DEFERRCV: xri x%x sz %d CPU %02x\n",
+                         ctxp->oxid, ctxp->size, smp_processor_id());
+
+        tgtp = phba->targetport->private;
+        atomic_inc(&tgtp->rcv_fcp_cmd_defer);
+        lpfc_rq_buf_free(phba, &nvmebuf->hbuf); /* repost */
+}
+
 static struct nvmet_fc_target_template lpfc_tgttemplate = {
         .targetport_delete = lpfc_nvmet_targetport_delete,
         .xmt_ls_rsp     = lpfc_nvmet_xmt_ls_rsp,
         .fcp_op         = lpfc_nvmet_xmt_fcp_op,
         .fcp_abort      = lpfc_nvmet_xmt_fcp_abort,
         .fcp_req_release = lpfc_nvmet_xmt_fcp_release,
+        .defer_rcv      = lpfc_nvmet_defer_rcv,
 
         .max_hw_queues  = 1,
         .max_sgl_segments = LPFC_NVMET_DEFAULT_SEGS,
@@ -1504,6 +1523,17 @@ lpfc_nvmet_unsol_fcp_buffer(struct lpfc_hba *phba,
                 return;
         }
 
+        /* Processing of FCP command is deferred */
+        if (rc == -EOVERFLOW) {
+                lpfc_nvmeio_data(phba,
+                                 "NVMET RCV BUSY: xri x%x sz %d from %06x\n",
+                                 oxid, size, sid);
+                /* defer reposting rcv buffer till .defer_rcv callback */
+                ctxp->rqb_buffer = nvmebuf;
+                atomic_inc(&tgtp->rcv_fcp_cmd_out);
+                return;
+        }
+
         atomic_inc(&tgtp->rcv_fcp_cmd_drop);
         lpfc_printf_log(phba, KERN_ERR, LOG_NVME_IOERR,
                         "6159 FCP Drop IO x%x: err x%x: x%x x%x x%x\n",
diff --git a/drivers/scsi/lpfc/lpfc_nvmet.h b/drivers/scsi/lpfc/lpfc_nvmet.h
index e675ef17be08..48a76788b003 100644
--- a/drivers/scsi/lpfc/lpfc_nvmet.h
+++ b/drivers/scsi/lpfc/lpfc_nvmet.h
@@ -49,6 +49,7 @@ struct lpfc_nvmet_tgtport {
         atomic_t rcv_fcp_cmd_in;
         atomic_t rcv_fcp_cmd_out;
         atomic_t rcv_fcp_cmd_drop;
+        atomic_t rcv_fcp_cmd_defer;
         atomic_t xmt_fcp_release;
 
         /* Stats counters - lpfc_nvmet_xmt_fcp_op */
diff --git a/include/linux/nvme-fc-driver.h b/include/linux/nvme-fc-driver.h
index 6c8c5d8041b7..2591878c1d48 100644
--- a/include/linux/nvme-fc-driver.h
+++ b/include/linux/nvme-fc-driver.h
@@ -346,6 +346,11 @@ struct nvme_fc_remote_port {
  *       indicating an FC transport Aborted status.
  *       Entrypoint is Mandatory.
  *
+ * @defer_rcv:  Called by the transport to signal the LLLD that it has
+ *       begun processing of a previously received NVME CMD IU. The LLDD
+ *       is now free to re-use the rcv buffer associated with the
+ *       nvmefc_tgt_fcp_req.
+ *
  * @max_hw_queues:  indicates the maximum number of hw queues the LLDD
  *       supports for cpu affinitization.
  *       Value is Mandatory. Must be at least 1.
@@ -846,6 +851,8 @@ struct nvmet_fc_target_template {
                                 struct nvmefc_tgt_fcp_req *fcpreq);
         void (*fcp_req_release)(struct nvmet_fc_target_port *tgtport,
                                 struct nvmefc_tgt_fcp_req *fcpreq);
+        void (*defer_rcv)(struct nvmet_fc_target_port *tgtport,
+                                struct nvmefc_tgt_fcp_req *fcpreq);
 
         u32     max_hw_queues;
         u16     max_sgl_segments;