[PATCH] smb: client: allocate enough space for MR WRs and ib_drain_qp()

[Stefan Metzmacher]

The IB_WR_REG_MR and IB_WR_LOCAL_INV operations for smbdirect_mr_io
structures should never fail because the submission or completion queues
are too small. So we allocate more send_wr depending on the (local) max
number of MRs.

While there also add additional space for ib_drain_qp().

This should make sure ib_post_send() will never fail
because the submission queue is full.

Fixes: f198186aa9bb ("CIFS: SMBD: Establish SMB Direct connection")
Fixes: cc55f65dd352 ("smb: client: make use of common smbdirect_socket_parameters")
Cc: Steve French <smfrench at gmail.com>
Cc: Tom Talpey <tom at talpey.com>
Cc: Long Li <longli at microsoft.com>
Cc: Namjae Jeon <linkinjeon at kernel.org>
Cc: linux-cifs at vger.kernel.org
Cc: samba-technical at lists.samba.org
Signed-off-by: Stefan Metzmacher <metze at samba.org>
---
 fs/smb/client/smbdirect.c | 36 +++++++++++++++++++++++-------------
 1 file changed, 23 insertions(+), 13 deletions(-)

diff --git a/fs/smb/client/smbdirect.c b/fs/smb/client/smbdirect.c
index 49e2df3ad1f0..068e1069eca5 100644
--- a/fs/smb/client/smbdirect.c
+++ b/fs/smb/client/smbdirect.c
@@ -1767,6 +1767,7 @@ static struct smbd_connection *_smbd_get_connection(
 	struct smbdirect_socket *sc;
 	struct smbdirect_socket_parameters *sp;
 	struct rdma_conn_param conn_param;
+	struct ib_qp_cap qp_cap;
 	struct ib_qp_init_attr qp_attr;
 	struct sockaddr_in *addr_in = (struct sockaddr_in *) dstaddr;
 	struct ib_port_immutable port_immutable;
@@ -1838,6 +1839,25 @@ static struct smbd_connection *_smbd_get_connection(
 		goto config_failed;
 	}
 
+	sp->responder_resources =
+		min_t(u8, sp->responder_resources,
+		      sc->ib.dev->attrs.max_qp_rd_atom);
+	log_rdma_mr(INFO, "responder_resources=%d\n",
+		sp->responder_resources);
+
+	/*
+	 * We use allocate sp->responder_resources * 2 MRs
+	 * and each MR needs WRs for REG and INV, so
+	 * we use '* 4'.
+	 *
+	 * +1 fot ib_drain_qp()
+	 */
+	memset(&qp_cap, 0, sizeof(qp_cap));
+	qp_cap.max_send_wr = sp->send_credit_target + sp->responder_resources * 4 + 1;
+	qp_cap.max_recv_wr = sp->recv_credit_max + 1;
+	qp_cap.max_send_sge = SMBDIRECT_SEND_IO_MAX_SGE;
+	qp_cap.max_recv_sge = SMBDIRECT_RECV_IO_MAX_SGE;
+
 	sc->ib.pd = ib_alloc_pd(sc->ib.dev, 0);
 	if (IS_ERR(sc->ib.pd)) {
 		rc = PTR_ERR(sc->ib.pd);
@@ -1848,7 +1868,7 @@ static struct smbd_connection *_smbd_get_connection(
 
 	sc->ib.send_cq =
 		ib_alloc_cq_any(sc->ib.dev, sc,
-				sp->send_credit_target, IB_POLL_SOFTIRQ);
+				qp_cap.max_send_wr, IB_POLL_SOFTIRQ);
 	if (IS_ERR(sc->ib.send_cq)) {
 		sc->ib.send_cq = NULL;
 		goto alloc_cq_failed;
@@ -1856,7 +1876,7 @@ static struct smbd_connection *_smbd_get_connection(
 
 	sc->ib.recv_cq =
 		ib_alloc_cq_any(sc->ib.dev, sc,
-				sp->recv_credit_max, IB_POLL_SOFTIRQ);
+				qp_cap.max_recv_wr, IB_POLL_SOFTIRQ);
 	if (IS_ERR(sc->ib.recv_cq)) {
 		sc->ib.recv_cq = NULL;
 		goto alloc_cq_failed;
@@ -1865,11 +1885,7 @@ static struct smbd_connection *_smbd_get_connection(
 	memset(&qp_attr, 0, sizeof(qp_attr));
 	qp_attr.event_handler = smbd_qp_async_error_upcall;
 	qp_attr.qp_context = sc;
-	qp_attr.cap.max_send_wr = sp->send_credit_target;
-	qp_attr.cap.max_recv_wr = sp->recv_credit_max;
-	qp_attr.cap.max_send_sge = SMBDIRECT_SEND_IO_MAX_SGE;
-	qp_attr.cap.max_recv_sge = SMBDIRECT_RECV_IO_MAX_SGE;
-	qp_attr.cap.max_inline_data = 0;
+	qp_attr.cap = qp_cap;
 	qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
 	qp_attr.qp_type = IB_QPT_RC;
 	qp_attr.send_cq = sc->ib.send_cq;
@@ -1883,12 +1899,6 @@ static struct smbd_connection *_smbd_get_connection(
 	}
 	sc->ib.qp = sc->rdma.cm_id->qp;
 
-	sp->responder_resources =
-		min_t(u8, sp->responder_resources,
-		      sc->ib.dev->attrs.max_qp_rd_atom);
-	log_rdma_mr(INFO, "responder_resources=%d\n",
-		sp->responder_resources);
-
 	memset(&conn_param, 0, sizeof(conn_param));
 	conn_param.initiator_depth = sp->initiator_depth;
 	conn_param.responder_resources = sp->responder_resources;
-- 
2.43.0