nvmet_fc: Rework target side abort handling

target transport:
----------------------
There are cases when there is a need to abort in-progress target
operations (writedata) so that controller termination or errors can
clean up. That can't happen currently as the abort is another target
op type, so it can't be used till the running one finishes (and it may
not).  Solve by removing the abort op type and creating a separate
downcall from the transport to the lldd to request an io to be aborted.

The transport will abort ios on queue teardown or io errors. In general
the transport tries to call the lldd abort only when the io state is
idle. Meaning: ops that transmit data (readdata or rsp) will always
finish their transmit (or the lldd will see a state on the
link or initiator port that fails the transmit) and the done call for
the operation will occur. The transport will wait for the op done
upcall before calling the abort function, and as the io is idle, the
io can be cleaned up immediately after the abort call; Similarly, ios
that are not waiting for data or transmitting data must be in the nvmet
layer being processed. The transport will wait for the nvmet layer
completion before calling the abort function, and as the io is idle,
the io can be cleaned up immediately after the abort call; As for ops
that are waiting for data (writedata), they may be outstanding
indefinitely if the lldd doesn't see a condition where the initiatior
port or link is bad. In those cases, the transport will call the abort
function and wait for the lldd's op done upcall for the operation, where
it will then clean up the io.

Additionally, if a lldd receives an ABTS and matches it to an outstanding
request in the transport, A new new transport upcall was created to abort
the outstanding request in the transport. The transport expects any
outstanding op call (readdata or writedata) will completed by the lldd and
the operation upcall made. The transport doesn't act on the reported
abort (e.g. clean up the io) until an op done upcall occurs, a new op is
attempted, or the nvmet layer completes the io processing.

fcloop:
----------------------
Updated to support the new target apis.
On fcp io aborts from the initiator, the loopback context is updated to
NULL out the half that has completed. The initiator side is immediately
called after the abort request with an io completion (abort status).
On fcp io aborts from the target, the io is stopped and the initiator side
sees it as an aborted io. Target side ops, perhaps in progress while the
initiator side is done, continue but noop the data movement as there's no
structure on the initiator side to reference.

patch also contains:
----------------------
Revised lpfc to support the new abort api

commonized rsp buffer syncing and nulling of private data based on
calling paths.

errors in op done calls don't take action on the fod. They're bad
operations which implies the fod may be bad.

Signed-off-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>

1 files changed, 130 insertions, 22 deletions

diff --git a/drivers/nvme/target/fcloop.c b/drivers/nvme/target/fcloop.c
index dbcafd30dd9b..aaa3dbe22bd5 100644
--- a/drivers/nvme/target/fcloop.c
+++ b/drivers/nvme/target/fcloop.c
@@ -246,7 +246,10 @@ struct fcloop_lsreq {
 struct fcloop_fcpreq {
 	struct fcloop_tport		*tport;
 	struct nvmefc_fcp_req		*fcpreq;
+	spinlock_t			reqlock;
 	u16				status;
+	bool				active;
+	bool				aborted;
 	struct work_struct		work;
 	struct nvmefc_tgt_fcp_req	tgt_fcp_req;
 };
@@ -254,6 +257,7 @@ struct fcloop_fcpreq {
 struct fcloop_ini_fcpreq {
 	struct nvmefc_fcp_req		*fcpreq;
 	struct fcloop_fcpreq		*tfcp_req;
+	struct work_struct		iniwork;
 };
 
 static inline struct fcloop_lsreq *
@@ -345,7 +349,21 @@ fcloop_xmt_ls_rsp(struct nvmet_fc_target_port *tport,
 }
 
 /*
- * FCP IO operation done. call back up initiator "done" flows.
+ * FCP IO operation done by initiator abort.
+ * call back up initiator "done" flows.
+ */
+static void
+fcloop_tgt_fcprqst_ini_done_work(struct work_struct *work)
+{
+	struct fcloop_ini_fcpreq *inireq =
+		container_of(work, struct fcloop_ini_fcpreq, iniwork);
+
+	inireq->fcpreq->done(inireq->fcpreq);
+}
+
+/*
+ * FCP IO operation done by target completion.
+ * call back up initiator "done" flows.
  */
 static void
 fcloop_tgt_fcprqst_done_work(struct work_struct *work)
@@ -353,9 +371,13 @@ fcloop_tgt_fcprqst_done_work(struct work_struct *work)
 	struct fcloop_fcpreq *tfcp_req =
 		container_of(work, struct fcloop_fcpreq, work);
 	struct fcloop_tport *tport = tfcp_req->tport;
-	struct nvmefc_fcp_req *fcpreq = tfcp_req->fcpreq;
+	struct nvmefc_fcp_req *fcpreq;
+
+	spin_lock(&tfcp_req->reqlock);
+	fcpreq = tfcp_req->fcpreq;
+	spin_unlock(&tfcp_req->reqlock);
 
-	if (tport->remoteport) {
+	if (tport->remoteport && fcpreq) {
 		fcpreq->status = tfcp_req->status;
 		fcpreq->done(fcpreq);
 	}
@@ -384,8 +406,10 @@ fcloop_fcp_req(struct nvme_fc_local_port *localport,
 
 	inireq->fcpreq = fcpreq;
 	inireq->tfcp_req = tfcp_req;
+	INIT_WORK(&inireq->iniwork, fcloop_tgt_fcprqst_ini_done_work);
 	tfcp_req->fcpreq = fcpreq;
 	tfcp_req->tport = rport->targetport->private;
+	spin_lock_init(&tfcp_req->reqlock);
 	INIT_WORK(&tfcp_req->work, fcloop_tgt_fcprqst_done_work);
 
 	ret = nvmet_fc_rcv_fcp_req(rport->targetport, &tfcp_req->tgt_fcp_req,
@@ -453,50 +477,86 @@ fcloop_fcp_op(struct nvmet_fc_target_port *tgtport,
 			struct nvmefc_tgt_fcp_req *tgt_fcpreq)
 {
 	struct fcloop_fcpreq *tfcp_req = tgt_fcp_req_to_fcpreq(tgt_fcpreq);
-	struct nvmefc_fcp_req *fcpreq = tfcp_req->fcpreq;
+	struct nvmefc_fcp_req *fcpreq;
 	u32 rsplen = 0, xfrlen = 0;
-	int fcp_err = 0;
+	int fcp_err = 0, active, aborted;
 	u8 op = tgt_fcpreq->op;
 
+	spin_lock(&tfcp_req->reqlock);
+	fcpreq = tfcp_req->fcpreq;
+	active = tfcp_req->active;
+	aborted = tfcp_req->aborted;
+	tfcp_req->active = true;
+	spin_unlock(&tfcp_req->reqlock);
+
+	if (unlikely(active))
+		/* illegal - call while i/o active */
+		return -EALREADY;
+
+	if (unlikely(aborted)) {
+		/* target transport has aborted i/o prior */
+		spin_lock(&tfcp_req->reqlock);
+		tfcp_req->active = false;
+		spin_unlock(&tfcp_req->reqlock);
+		tgt_fcpreq->transferred_length = 0;
+		tgt_fcpreq->fcp_error = -ECANCELED;
+		tgt_fcpreq->done(tgt_fcpreq);
+		return 0;
+	}
+
+	/*
+	 * if fcpreq is NULL, the I/O has been aborted (from
+	 * initiator side). For the target side, act as if all is well
+	 * but don't actually move data.
+	 */
+
 	switch (op) {
 	case NVMET_FCOP_WRITEDATA:
 		xfrlen = tgt_fcpreq->transfer_length;
-		fcloop_fcp_copy_data(op, tgt_fcpreq->sg, fcpreq->first_sgl,
-					tgt_fcpreq->offset, xfrlen);
-		fcpreq->transferred_length += xfrlen;
+		if (fcpreq) {
+			fcloop_fcp_copy_data(op, tgt_fcpreq->sg,
+					fcpreq->first_sgl, tgt_fcpreq->offset,
+					xfrlen);
+			fcpreq->transferred_length += xfrlen;
+		}
 		break;
 
 	case NVMET_FCOP_READDATA:
 	case NVMET_FCOP_READDATA_RSP:
 		xfrlen = tgt_fcpreq->transfer_length;
-		fcloop_fcp_copy_data(op, tgt_fcpreq->sg, fcpreq->first_sgl,
-					tgt_fcpreq->offset, xfrlen);
-		fcpreq->transferred_length += xfrlen;
+		if (fcpreq) {
+			fcloop_fcp_copy_data(op, tgt_fcpreq->sg,
+					fcpreq->first_sgl, tgt_fcpreq->offset,
+					xfrlen);
+			fcpreq->transferred_length += xfrlen;
+		}
 		if (op == NVMET_FCOP_READDATA)
 			break;
 
 		/* Fall-Thru to RSP handling */
 
 	case NVMET_FCOP_RSP:
-		rsplen = ((fcpreq->rsplen < tgt_fcpreq->rsplen) ?
-				fcpreq->rsplen : tgt_fcpreq->rsplen);
-		memcpy(fcpreq->rspaddr, tgt_fcpreq->rspaddr, rsplen);
-		if (rsplen < tgt_fcpreq->rsplen)
-			fcp_err = -E2BIG;
-		fcpreq->rcv_rsplen = rsplen;
-		fcpreq->status = 0;
+		if (fcpreq) {
+			rsplen = ((fcpreq->rsplen < tgt_fcpreq->rsplen) ?
+					fcpreq->rsplen : tgt_fcpreq->rsplen);
+			memcpy(fcpreq->rspaddr, tgt_fcpreq->rspaddr, rsplen);
+			if (rsplen < tgt_fcpreq->rsplen)
+				fcp_err = -E2BIG;
+			fcpreq->rcv_rsplen = rsplen;
+			fcpreq->status = 0;
+		}
 		tfcp_req->status = 0;
 		break;
 
-	case NVMET_FCOP_ABORT:
-		tfcp_req->status = NVME_SC_FC_TRANSPORT_ABORTED;
-		break;
-
 	default:
 		fcp_err = -EINVAL;
 		break;
 	}
 
+	spin_lock(&tfcp_req->reqlock);
+	tfcp_req->active = false;
+	spin_unlock(&tfcp_req->reqlock);
+
 	tgt_fcpreq->transferred_length = xfrlen;
 	tgt_fcpreq->fcp_error = fcp_err;
 	tgt_fcpreq->done(tgt_fcpreq);
@@ -505,6 +565,32 @@ fcloop_fcp_op(struct nvmet_fc_target_port *tgtport,
 }
 
 static void
+fcloop_tgt_fcp_abort(struct nvmet_fc_target_port *tgtport,
+			struct nvmefc_tgt_fcp_req *tgt_fcpreq)
+{
+	struct fcloop_fcpreq *tfcp_req = tgt_fcp_req_to_fcpreq(tgt_fcpreq);
+	int active;
+
+	/*
+	 * mark aborted only in case there were 2 threads in transport
+	 * (one doing io, other doing abort) and only kills ops posted
+	 * after the abort request
+	 */
+	spin_lock(&tfcp_req->reqlock);
+	active = tfcp_req->active;
+	tfcp_req->aborted = true;
+	spin_unlock(&tfcp_req->reqlock);
+
+	tfcp_req->status = NVME_SC_FC_TRANSPORT_ABORTED;
+
+	/*
+	 * nothing more to do. If io wasn't active, the transport should
+	 * immediately call the req_release. If it was active, the op
+	 * will complete, and the lldd should call req_release.
+	 */
+}
+
+static void
 fcloop_fcp_req_release(struct nvmet_fc_target_port *tgtport,
 			struct nvmefc_tgt_fcp_req *tgt_fcpreq)
 {
@@ -526,6 +612,27 @@ fcloop_fcp_abort(struct nvme_fc_local_port *localport,
 			void *hw_queue_handle,
 			struct nvmefc_fcp_req *fcpreq)
 {
+	struct fcloop_rport *rport = remoteport->private;
+	struct fcloop_ini_fcpreq *inireq = fcpreq->private;
+	struct fcloop_fcpreq *tfcp_req = inireq->tfcp_req;
+
+	if (!tfcp_req)
+		/* abort has already been called */
+		return;
+
+	if (rport->targetport)
+		nvmet_fc_rcv_fcp_abort(rport->targetport,
+					&tfcp_req->tgt_fcp_req);
+
+	/* break initiator/target relationship for io */
+	spin_lock(&tfcp_req->reqlock);
+	inireq->tfcp_req = NULL;
+	tfcp_req->fcpreq = NULL;
+	spin_unlock(&tfcp_req->reqlock);
+
+	/* post the aborted io completion */
+	fcpreq->status = -ECANCELED;
+	schedule_work(&inireq->iniwork);
 }
 
 static void
@@ -583,6 +690,7 @@ struct nvmet_fc_target_template tgttemplate = {
 	.targetport_delete	= fcloop_targetport_delete,
 	.xmt_ls_rsp		= fcloop_xmt_ls_rsp,
 	.fcp_op			= fcloop_fcp_op,
+	.fcp_abort		= fcloop_tgt_fcp_abort,
 	.fcp_req_release	= fcloop_fcp_req_release,
 	.max_hw_queues		= FCLOOP_HW_QUEUES,
 	.max_sgl_segments	= FCLOOP_SGL_SEGS,