[PATCH RFC 05/12] xprtrdma: Remove fr_state

[Chuck Lever <chuck.lever@oracle.com>]

Since both the Send and Receive completion queues are processed in
a workqueue context, it should be safe to DMA unmap and return MRs
to the free or recycle lists directly in the completion handlers.

Doing this means rpcrdma_frwr no longer needs to track the state
of each MR... a VALID or FLUSHED MR can no longer appear on an
xprt's MR free list.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 include/trace/events/rpcrdma.h  |   19 ----
 net/sunrpc/xprtrdma/frwr_ops.c  |  202 ++++++++++++++++++---------------------
 net/sunrpc/xprtrdma/rpc_rdma.c  |    2 
 net/sunrpc/xprtrdma/xprt_rdma.h |   11 --
 4 files changed, 95 insertions(+), 139 deletions(-)

diff --git a/include/trace/events/rpcrdma.h b/include/trace/events/rpcrdma.h
index a4ab3a2..7fe21ba 100644
--- a/include/trace/events/rpcrdma.h
+++ b/include/trace/events/rpcrdma.h
@@ -181,18 +181,6 @@
 				),					\
 				TP_ARGS(task, mr, nsegs))
 
-TRACE_DEFINE_ENUM(FRWR_IS_INVALID);
-TRACE_DEFINE_ENUM(FRWR_IS_VALID);
-TRACE_DEFINE_ENUM(FRWR_FLUSHED_FR);
-TRACE_DEFINE_ENUM(FRWR_FLUSHED_LI);
-
-#define xprtrdma_show_frwr_state(x)					\
-		__print_symbolic(x,					\
-				{ FRWR_IS_INVALID, "INVALID" },		\
-				{ FRWR_IS_VALID, "VALID" },		\
-				{ FRWR_FLUSHED_FR, "FLUSHED_FR" },	\
-				{ FRWR_FLUSHED_LI, "FLUSHED_LI" })
-
 DECLARE_EVENT_CLASS(xprtrdma_frwr_done,
 	TP_PROTO(
 		const struct ib_wc *wc,
@@ -203,22 +191,19 @@
 
 	TP_STRUCT__entry(
 		__field(const void *, mr)
-		__field(unsigned int, state)
 		__field(unsigned int, status)
 		__field(unsigned int, vendor_err)
 	),
 
 	TP_fast_assign(
 		__entry->mr = container_of(frwr, struct rpcrdma_mr, frwr);
-		__entry->state = frwr->fr_state;
 		__entry->status = wc->status;
 		__entry->vendor_err = __entry->status ? wc->vendor_err : 0;
 	),
 
 	TP_printk(
-		"mr=%p state=%s: %s (%u/0x%x)",
-		__entry->mr, xprtrdma_show_frwr_state(__entry->state),
-		rdma_show_wc_status(__entry->status),
+		"mr=%p: %s (%u/0x%x)",
+		__entry->mr, rdma_show_wc_status(__entry->status),
 		__entry->status, __entry->vendor_err
 	)
 );
diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
index ac47314..99871fbf 100644
--- a/net/sunrpc/xprtrdma/frwr_ops.c
+++ b/net/sunrpc/xprtrdma/frwr_ops.c
@@ -168,7 +168,6 @@ int frwr_init_mr(struct rpcrdma_ia *ia, struct rpcrdma_mr *mr)
 		goto out_list_err;
 
 	mr->frwr.fr_mr = frmr;
-	mr->frwr.fr_state = FRWR_IS_INVALID;
 	mr->mr_dir = DMA_NONE;
 	INIT_LIST_HEAD(&mr->mr_list);
 	INIT_WORK(&mr->mr_recycle, frwr_mr_recycle_worker);
@@ -298,65 +297,6 @@ size_t frwr_maxpages(struct rpcrdma_xprt *r_xprt)
 }
 
 /**
- * frwr_wc_fastreg - Invoked by RDMA provider for a flushed FastReg WC
- * @cq:	completion queue (ignored)
- * @wc:	completed WR
- *
- */
-static void
-frwr_wc_fastreg(struct ib_cq *cq, struct ib_wc *wc)
-{
-	struct ib_cqe *cqe = wc->wr_cqe;
-	struct rpcrdma_frwr *frwr =
-			container_of(cqe, struct rpcrdma_frwr, fr_cqe);
-
-	/* WARNING: Only wr_cqe and status are reliable at this point */
-	if (wc->status != IB_WC_SUCCESS)
-		frwr->fr_state = FRWR_FLUSHED_FR;
-	trace_xprtrdma_wc_fastreg(wc, frwr);
-}
-
-/**
- * frwr_wc_localinv - Invoked by RDMA provider for a flushed LocalInv WC
- * @cq:	completion queue (ignored)
- * @wc:	completed WR
- *
- */
-static void
-frwr_wc_localinv(struct ib_cq *cq, struct ib_wc *wc)
-{
-	struct ib_cqe *cqe = wc->wr_cqe;
-	struct rpcrdma_frwr *frwr = container_of(cqe, struct rpcrdma_frwr,
-						 fr_cqe);
-
-	/* WARNING: Only wr_cqe and status are reliable at this point */
-	if (wc->status != IB_WC_SUCCESS)
-		frwr->fr_state = FRWR_FLUSHED_LI;
-	trace_xprtrdma_wc_li(wc, frwr);
-}
-
-/**
- * frwr_wc_localinv_wake - Invoked by RDMA provider for a signaled LocalInv WC
- * @cq:	completion queue (ignored)
- * @wc:	completed WR
- *
- * Awaken anyone waiting for an MR to finish being fenced.
- */
-static void
-frwr_wc_localinv_wake(struct ib_cq *cq, struct ib_wc *wc)
-{
-	struct ib_cqe *cqe = wc->wr_cqe;
-	struct rpcrdma_frwr *frwr = container_of(cqe, struct rpcrdma_frwr,
-						 fr_cqe);
-
-	/* WARNING: Only wr_cqe and status are reliable at this point */
-	if (wc->status != IB_WC_SUCCESS)
-		frwr->fr_state = FRWR_FLUSHED_LI;
-	trace_xprtrdma_wc_li_wake(wc, frwr);
-	complete(&frwr->fr_linv_done);
-}
-
-/**
  * frwr_map - Register a memory region
  * @r_xprt: controlling transport
  * @seg: memory region co-ordinates
@@ -378,23 +318,15 @@ struct rpcrdma_mr_seg *frwr_map(struct rpcrdma_xprt *r_xprt,
 {
 	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
 	bool holes_ok = ia->ri_mrtype == IB_MR_TYPE_SG_GAPS;
-	struct rpcrdma_frwr *frwr;
 	struct rpcrdma_mr *mr;
 	struct ib_mr *ibmr;
 	struct ib_reg_wr *reg_wr;
 	int i, n;
 	u8 key;
 
-	mr = NULL;
-	do {
-		if (mr)
-			rpcrdma_mr_recycle(mr);
-		mr = rpcrdma_mr_get(r_xprt);
-		if (!mr)
-			goto out_getmr_err;
-	} while (mr->frwr.fr_state != FRWR_IS_INVALID);
-	frwr = &mr->frwr;
-	frwr->fr_state = FRWR_IS_VALID;
+	mr = rpcrdma_mr_get(r_xprt);
+	if (!mr)
+		goto out_getmr_err;
 
 	if (nsegs > ia->ri_max_frwr_depth)
 		nsegs = ia->ri_max_frwr_depth;
@@ -423,7 +355,7 @@ struct rpcrdma_mr_seg *frwr_map(struct rpcrdma_xprt *r_xprt,
 	if (!mr->mr_nents)
 		goto out_dmamap_err;
 
-	ibmr = frwr->fr_mr;
+	ibmr = mr->frwr.fr_mr;
 	n = ib_map_mr_sg(ibmr, mr->mr_sg, mr->mr_nents, NULL, PAGE_SIZE);
 	if (unlikely(n != mr->mr_nents))
 		goto out_mapmr_err;
@@ -433,7 +365,7 @@ struct rpcrdma_mr_seg *frwr_map(struct rpcrdma_xprt *r_xprt,
 	key = (u8)(ibmr->rkey & 0x000000FF);
 	ib_update_fast_reg_key(ibmr, ++key);
 
-	reg_wr = &frwr->fr_regwr;
+	reg_wr = &mr->frwr.fr_regwr;
 	reg_wr->mr = ibmr;
 	reg_wr->key = ibmr->rkey;
 	reg_wr->access = writing ?
@@ -465,6 +397,23 @@ struct rpcrdma_mr_seg *frwr_map(struct rpcrdma_xprt *r_xprt,
 }
 
 /**
+ * frwr_wc_fastreg - Invoked by RDMA provider for a flushed FastReg WC
+ * @cq:	completion queue (ignored)
+ * @wc:	completed WR
+ *
+ */
+static void frwr_wc_fastreg(struct ib_cq *cq, struct ib_wc *wc)
+{
+	struct ib_cqe *cqe = wc->wr_cqe;
+	struct rpcrdma_frwr *frwr =
+		container_of(cqe, struct rpcrdma_frwr, fr_cqe);
+
+	/* WARNING: Only wr_cqe and status are reliable at this point */
+	trace_xprtrdma_wc_fastreg(wc, frwr);
+	/* The MR will get recycled when the associated req is retransmitted */
+}
+
+/**
  * frwr_send - post Send WR containing the RPC Call message
  * @ia: interface adapter
  * @req: Prepared RPC Call
@@ -516,65 +465,104 @@ void frwr_reminv(struct rpcrdma_rep *rep, struct list_head *mrs)
 		if (mr->mr_handle == rep->rr_inv_rkey) {
 			list_del_init(&mr->mr_list);
 			trace_xprtrdma_mr_remoteinv(mr);
-			mr->frwr.fr_state = FRWR_IS_INVALID;
 			rpcrdma_mr_unmap_and_put(mr);
 			break;	/* only one invalidated MR per RPC */
 		}
 }
 
+static void __frwr_release_mr(struct ib_wc *wc, struct rpcrdma_mr *mr)
+{
+	if (wc->status != IB_WC_SUCCESS)
+		rpcrdma_mr_recycle(mr);
+	else
+		rpcrdma_mr_unmap_and_put(mr);
+}
+
 /**
- * frwr_unmap_sync - invalidate memory regions that were registered for @req
- * @r_xprt: controlling transport
- * @mrs: list of MRs to process
+ * frwr_wc_localinv - Invoked by RDMA provider for a LOCAL_INV WC
+ * @cq:	completion queue (ignored)
+ * @wc:	completed WR
  *
- * Sleeps until it is safe for the host CPU to access the
- * previously mapped memory regions.
+ */
+static void frwr_wc_localinv(struct ib_cq *cq, struct ib_wc *wc)
+{
+	struct ib_cqe *cqe = wc->wr_cqe;
+	struct rpcrdma_frwr *frwr =
+		container_of(cqe, struct rpcrdma_frwr, fr_cqe);
+	struct rpcrdma_mr *mr = container_of(frwr, struct rpcrdma_mr, frwr);
+
+	/* WARNING: Only wr_cqe and status are reliable at this point */
+	__frwr_release_mr(wc, mr);
+	trace_xprtrdma_wc_li(wc, frwr);
+}
+
+/**
+ * frwr_wc_localinv_wake - Invoked by RDMA provider for a LOCAL_INV WC
+ * @cq:	completion queue (ignored)
+ * @wc:	completed WR
  *
- * Caller ensures that @mrs is not empty before the call. This
- * function empties the list.
+ * Awaken anyone waiting for an MR to finish being fenced.
  */
-void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct list_head *mrs)
+static void frwr_wc_localinv_wake(struct ib_cq *cq, struct ib_wc *wc)
+{
+	struct ib_cqe *cqe = wc->wr_cqe;
+	struct rpcrdma_frwr *frwr =
+		container_of(cqe, struct rpcrdma_frwr, fr_cqe);
+	struct rpcrdma_mr *mr = container_of(frwr, struct rpcrdma_mr, frwr);
+
+	/* WARNING: Only wr_cqe and status are reliable at this point */
+	__frwr_release_mr(wc, mr);
+	trace_xprtrdma_wc_li_wake(wc, frwr);
+	complete(&frwr->fr_linv_done);
+}
+
+/**
+ * frwr_unmap_sync - invalidate memory regions that were registered for @req
+ * @r_xprt: controlling transport instance
+ * @req: rpcrdma_req with a non-empty list of MRs to process
+ *
+ * Sleeps until it is safe for the host CPU to access the previously mapped
+ * memory regions.
+ */
+void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
 {
 	struct ib_send_wr *first, **prev, *last;
 	const struct ib_send_wr *bad_wr;
-	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
 	struct rpcrdma_frwr *frwr;
 	struct rpcrdma_mr *mr;
-	int count, rc;
+	int rc;
 
 	/* ORDER: Invalidate all of the MRs first
 	 *
 	 * Chain the LOCAL_INV Work Requests and post them with
 	 * a single ib_post_send() call.
 	 */
-	frwr = NULL;
-	count = 0;
 	prev = &first;
-	list_for_each_entry(mr, mrs, mr_list) {
-		mr->frwr.fr_state = FRWR_IS_INVALID;
+	while (!list_empty(&req->rl_registered)) {
+		mr = rpcrdma_mr_pop(&req->rl_registered);
 
-		frwr = &mr->frwr;
 		trace_xprtrdma_mr_localinv(mr);
+		r_xprt->rx_stats.local_inv_needed++;
 
+		frwr = &mr->frwr;
 		frwr->fr_cqe.done = frwr_wc_localinv;
 		last = &frwr->fr_invwr;
-		memset(last, 0, sizeof(*last));
+		last->next = NULL;
 		last->wr_cqe = &frwr->fr_cqe;
+		last->sg_list = NULL;
+		last->num_sge = 0;
 		last->opcode = IB_WR_LOCAL_INV;
+		last->send_flags = IB_SEND_SIGNALED;
 		last->ex.invalidate_rkey = mr->mr_handle;
-		count++;
 
 		*prev = last;
 		prev = &last->next;
 	}
-	if (!frwr)
-		goto unmap;
 
 	/* Strong send queue ordering guarantees that when the
 	 * last WR in the chain completes, all WRs in the chain
 	 * are complete.
 	 */
-	last->send_flags = IB_SEND_SIGNALED;
 	frwr->fr_cqe.done = frwr_wc_localinv_wake;
 	reinit_completion(&frwr->fr_linv_done);
 
@@ -582,26 +570,18 @@ void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct list_head *mrs)
 	 * replaces the QP. The RPC reply handler won't call us
 	 * unless ri_id->qp is a valid pointer.
 	 */
-	r_xprt->rx_stats.local_inv_needed++;
 	bad_wr = NULL;
-	rc = ib_post_send(ia->ri_id->qp, first, &bad_wr);
-	if (bad_wr != first)
-		wait_for_completion(&frwr->fr_linv_done);
-	if (rc)
-		goto out_release;
+	rc = ib_post_send(r_xprt->rx_ia.ri_id->qp, first, &bad_wr);
+	trace_xprtrdma_post_send(req, rc);
 
-	/* ORDER: Now DMA unmap all of the MRs, and return
-	 * them to the free MR list.
+	/* The final LOCAL_INV WR in the chain is supposed to
+	 * do the wake. If it never gets posted, the wake will
+	 * not happen, so don't wait in that case.
 	 */
-unmap:
-	while (!list_empty(mrs)) {
-		mr = rpcrdma_mr_pop(mrs);
-		rpcrdma_mr_unmap_and_put(mr);
-	}
-	return;
-
-out_release:
-	pr_err("rpcrdma: FRWR invalidate ib_post_send returned %i\n", rc);
+	if (bad_wr != first)
+		wait_for_completion(&frwr->fr_linv_done);
+	if (!rc)
+		return;
 
 	/* Unmap and release the MRs in the LOCAL_INV WRs that did not
 	 * get posted.
diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index 77fc1e4..6c049fd 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -1277,7 +1277,7 @@ void rpcrdma_release_rqst(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
 	 * RPC has relinquished all its Send Queue entries.
 	 */
 	if (!list_empty(&req->rl_registered))
-		frwr_unmap_sync(r_xprt, &req->rl_registered);
+		frwr_unmap_sync(r_xprt, req);
 
 	/* Ensure that any DMA mapped pages associated with
 	 * the Send of the RPC Call have been unmapped before
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 3c39aa3..a9de116 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -240,17 +240,9 @@ struct rpcrdma_sendctx {
  * An external memory region is any buffer or page that is registered
  * on the fly (ie, not pre-registered).
  */
-enum rpcrdma_frwr_state {
-	FRWR_IS_INVALID,	/* ready to be used */
-	FRWR_IS_VALID,		/* in use */
-	FRWR_FLUSHED_FR,	/* flushed FASTREG WR */
-	FRWR_FLUSHED_LI,	/* flushed LOCALINV WR */
-};
-
 struct rpcrdma_frwr {
 	struct ib_mr			*fr_mr;
 	struct ib_cqe			fr_cqe;
-	enum rpcrdma_frwr_state		fr_state;
 	struct completion		fr_linv_done;
 	union {
 		struct ib_reg_wr	fr_regwr;
@@ -567,8 +559,7 @@ struct rpcrdma_mr_seg *frwr_map(struct rpcrdma_xprt *r_xprt,
 				struct rpcrdma_mr **mr);
 int frwr_send(struct rpcrdma_ia *ia, struct rpcrdma_req *req);
 void frwr_reminv(struct rpcrdma_rep *rep, struct list_head *mrs);
-void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt,
-		     struct list_head *mrs);
+void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req);
 
 /*
  * RPC/RDMA protocol calls - xprtrdma/rpc_rdma.c