nvmet_fc: add defer_req callback for deferment of cmd buffer return (0fb228d3) · Commits · 戴 / test

drivers/nvme/target/fc.c

+184 −28

Original line number	Diff line number	Diff line
		@@ -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 the reference taken at queue lookup and fod allocation
		*/
		/* Release reference taken at queue lookup and fod allocation */
		nvmet_fc_tgt_q_put(queue);
		return;
		}

		tgtport->ops->fcp_req_release(&tgtport->fc_target_port, fcpreq);
		/* 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);

		/*
		* Leave the queue lookup get reference taken when
		* fod was originally allocated.
		*/
		}

		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)) \|\|
		@@ -2214,30 +2339,61 @@ 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) {
		/* release the queue lookup reference */
		nvmet_fc_tgt_q_put(queue);
		return -ENOENT;
		}
		if (fod) {
		spin_unlock_irqrestore(&queue->qlock, flags);

		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);

		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);
		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;
		}

		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);

		/* 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);
		}

		/* 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);

		/**

include/linux/nvme-fc-driver.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -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;

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