Merge tag 'nfs-for-4.9-3' of git://git.linux-nfs.org/projects/anna/linux-nfs

Pull NFS client bugfixes from Anna Schumaker:
 "Most of these fix regressions in 4.9, and none are going to stable
  this time around.

  Bugfixes:
   - Trim extra slashes in v4 nfs_paths to fix tools that use this
   - Fix a -Wmaybe-uninitialized warnings
   - Fix suspicious RCU usages
   - Fix Oops when mounting multiple servers at once
   - Suppress a false-positive pNFS error
   - Fix a DMAR failure in NFS over RDMA"

* tag 'nfs-for-4.9-3' of git://git.linux-nfs.org/projects/anna/linux-nfs:
  xprtrdma: Fix DMAR failure in frwr_op_map() after reconnect
  fs/nfs: Fix used uninitialized warn in nfs4_slot_seqid_in_use()
  NFS: Don't print a pNFS error if we aren't using pNFS
  NFS: Ignore connections that have cl_rpcclient uninitialized
  SUNRPC: Fix suspicious RCU usage
  NFSv4.1: work around -Wmaybe-uninitialized warning
  NFS: Trim extra slash in v4 nfs_path

3 files changed, 29 insertions, 18 deletions

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 34dd7b26ee5f..62a482790937 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -2753,14 +2753,18 @@ EXPORT_SYMBOL_GPL(rpc_cap_max_reconnect_timeout);
 
 void rpc_clnt_xprt_switch_put(struct rpc_clnt *clnt)
 {
+	rcu_read_lock();
 	xprt_switch_put(rcu_dereference(clnt->cl_xpi.xpi_xpswitch));
+	rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(rpc_clnt_xprt_switch_put);
 
 void rpc_clnt_xprt_switch_add_xprt(struct rpc_clnt *clnt, struct rpc_xprt *xprt)
 {
+	rcu_read_lock();
 	rpc_xprt_switch_add_xprt(rcu_dereference(clnt->cl_xpi.xpi_xpswitch),
 				 xprt);
+	rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(rpc_clnt_xprt_switch_add_xprt);
 
@@ -2770,9 +2774,8 @@ bool rpc_clnt_xprt_switch_has_addr(struct rpc_clnt *clnt,
 	struct rpc_xprt_switch *xps;
 	bool ret;
 
-	xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch);
-
 	rcu_read_lock();
+	xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch);
 	ret = rpc_xprt_switch_has_addr(xps, sap);
 	rcu_read_unlock();
 	return ret;
diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
index 210949562786..26b26beef2d4 100644
--- a/net/sunrpc/xprtrdma/frwr_ops.c
+++ b/net/sunrpc/xprtrdma/frwr_ops.c
@@ -44,18 +44,20 @@
  * being done.
  *
  * When the underlying transport disconnects, MRs are left in one of
- * three states:
+ * four states:
  *
  * INVALID:	The MR was not in use before the QP entered ERROR state.
- *		(Or, the LOCAL_INV WR has not completed or flushed yet).
- *
- * STALE:	The MR was being registered or unregistered when the QP
- *		entered ERROR state, and the pending WR was flushed.
  *
  * VALID:	The MR was registered before the QP entered ERROR state.
  *
- * When frwr_op_map encounters STALE and VALID MRs, they are recovered
- * with ib_dereg_mr and then are re-initialized. Beause MR recovery
+ * FLUSHED_FR:	The MR was being registered when the QP entered ERROR
+ *		state, and the pending WR was flushed.
+ *
+ * FLUSHED_LI:	The MR was being invalidated when the QP entered ERROR
+ *		state, and the pending WR was flushed.
+ *
+ * When frwr_op_map encounters FLUSHED and VALID MRs, they are recovered
+ * with ib_dereg_mr and then are re-initialized. Because MR recovery
  * allocates fresh resources, it is deferred to a workqueue, and the
  * recovered MRs are placed back on the rb_mws list when recovery is
  * complete. frwr_op_map allocates another MR for the current RPC while
@@ -177,12 +179,15 @@ __frwr_reset_mr(struct rpcrdma_ia *ia, struct rpcrdma_mw *r)
 static void
 frwr_op_recover_mr(struct rpcrdma_mw *mw)
 {
+	enum rpcrdma_frmr_state state = mw->frmr.fr_state;
 	struct rpcrdma_xprt *r_xprt = mw->mw_xprt;
 	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
 	int rc;
 
 	rc = __frwr_reset_mr(ia, mw);
-	ib_dma_unmap_sg(ia->ri_device, mw->mw_sg, mw->mw_nents, mw->mw_dir);
+	if (state != FRMR_FLUSHED_LI)
+		ib_dma_unmap_sg(ia->ri_device,
+				mw->mw_sg, mw->mw_nents, mw->mw_dir);
 	if (rc)
 		goto out_release;
 
@@ -262,10 +267,8 @@ frwr_op_maxpages(struct rpcrdma_xprt *r_xprt)
 }
 
 static void
-__frwr_sendcompletion_flush(struct ib_wc *wc, struct rpcrdma_frmr *frmr,
-			    const char *wr)
+__frwr_sendcompletion_flush(struct ib_wc *wc, const char *wr)
 {
-	frmr->fr_state = FRMR_IS_STALE;
 	if (wc->status != IB_WC_WR_FLUSH_ERR)
 		pr_err("rpcrdma: %s: %s (%u/0x%x)\n",
 		       wr, ib_wc_status_msg(wc->status),
@@ -288,7 +291,8 @@ frwr_wc_fastreg(struct ib_cq *cq, struct ib_wc *wc)
 	if (wc->status != IB_WC_SUCCESS) {
 		cqe = wc->wr_cqe;
 		frmr = container_of(cqe, struct rpcrdma_frmr, fr_cqe);
-		__frwr_sendcompletion_flush(wc, frmr, "fastreg");
+		frmr->fr_state = FRMR_FLUSHED_FR;
+		__frwr_sendcompletion_flush(wc, "fastreg");
 	}
 }
 
@@ -308,7 +312,8 @@ frwr_wc_localinv(struct ib_cq *cq, struct ib_wc *wc)
 	if (wc->status != IB_WC_SUCCESS) {
 		cqe = wc->wr_cqe;
 		frmr = container_of(cqe, struct rpcrdma_frmr, fr_cqe);
-		__frwr_sendcompletion_flush(wc, frmr, "localinv");
+		frmr->fr_state = FRMR_FLUSHED_LI;
+		__frwr_sendcompletion_flush(wc, "localinv");
 	}
 }
 
@@ -328,8 +333,10 @@ frwr_wc_localinv_wake(struct ib_cq *cq, struct ib_wc *wc)
 	/* WARNING: Only wr_cqe and status are reliable at this point */
 	cqe = wc->wr_cqe;
 	frmr = container_of(cqe, struct rpcrdma_frmr, fr_cqe);
-	if (wc->status != IB_WC_SUCCESS)
-		__frwr_sendcompletion_flush(wc, frmr, "localinv");
+	if (wc->status != IB_WC_SUCCESS) {
+		frmr->fr_state = FRMR_FLUSHED_LI;
+		__frwr_sendcompletion_flush(wc, "localinv");
+	}
 	complete(&frmr->fr_linv_done);
 }
 
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 0d35b761c883..6e1bba358203 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -216,7 +216,8 @@ struct rpcrdma_rep {
 enum rpcrdma_frmr_state {
 	FRMR_IS_INVALID,	/* ready to be used */
 	FRMR_IS_VALID,		/* in use */
-	FRMR_IS_STALE,		/* failed completion */
+	FRMR_FLUSHED_FR,	/* flushed FASTREG WR */
+	FRMR_FLUSHED_LI,	/* flushed LOCALINV WR */
 };
 
 struct rpcrdma_frmr {