Merge tag 'nfsd-4.7-1' of git://linux-nfs.org/~bfields/linux

Pull nfsd bugfixes from Bruce Fields:
 "Oleg Drokin found and fixed races in the nfsd4 state code that go back
  to the big nfs4_lock_state removal around 3.17 (but that were also
  probably hard to reproduce before client changes in 3.20 allowed the
  client to perform parallel opens).

  Also fix a 4.1 backchannel crash due to rpc multipath changes in 4.6.
  Trond acked the client-side rpc fixes going through my tree"

* tag 'nfsd-4.7-1' of git://linux-nfs.org/~bfields/linux:
  nfsd: Make init_open_stateid() a bit more whole
  nfsd: Extend the mutex holding region around in nfsd4_process_open2()
  nfsd: Always lock state exclusively.
  rpc: share one xps between all backchannels
  nfsd4/rpc: move backchannel create logic into rpc code
  SUNRPC: fix xprt leak on xps allocation failure
  nfsd: Fix NFSD_MDS_PR_KEY on 32-bit by adding ULL postfix

3 files changed, 28 insertions, 6 deletions

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 06b4df9faaa1..2808d550d273 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -446,16 +446,27 @@ out_no_rpciod:
 	return ERR_PTR(err);
 }
 
-struct rpc_clnt *rpc_create_xprt(struct rpc_create_args *args,
+static struct rpc_clnt *rpc_create_xprt(struct rpc_create_args *args,
 					struct rpc_xprt *xprt)
 {
 	struct rpc_clnt *clnt = NULL;
 	struct rpc_xprt_switch *xps;
 
-	xps = xprt_switch_alloc(xprt, GFP_KERNEL);
-	if (xps == NULL)
-		return ERR_PTR(-ENOMEM);
-
+	if (args->bc_xprt && args->bc_xprt->xpt_bc_xps) {
+		WARN_ON(args->protocol != XPRT_TRANSPORT_BC_TCP);
+		xps = args->bc_xprt->xpt_bc_xps;
+		xprt_switch_get(xps);
+	} else {
+		xps = xprt_switch_alloc(xprt, GFP_KERNEL);
+		if (xps == NULL) {
+			xprt_put(xprt);
+			return ERR_PTR(-ENOMEM);
+		}
+		if (xprt->bc_xprt) {
+			xprt_switch_get(xps);
+			xprt->bc_xprt->xpt_bc_xps = xps;
+		}
+	}
 	clnt = rpc_new_client(args, xps, xprt, NULL);
 	if (IS_ERR(clnt))
 		return clnt;
@@ -483,7 +494,6 @@ struct rpc_clnt *rpc_create_xprt(struct rpc_create_args *args,
 
 	return clnt;
 }
-EXPORT_SYMBOL_GPL(rpc_create_xprt);
 
 /**
  * rpc_create - create an RPC client and transport with one call
@@ -509,6 +519,15 @@ struct rpc_clnt *rpc_create(struct rpc_create_args *args)
 	};
 	char servername[48];
 
+	if (args->bc_xprt) {
+		WARN_ON(args->protocol != XPRT_TRANSPORT_BC_TCP);
+		xprt = args->bc_xprt->xpt_bc_xprt;
+		if (xprt) {
+			xprt_get(xprt);
+			return rpc_create_xprt(args, xprt);
+		}
+	}
+
 	if (args->flags & RPC_CLNT_CREATE_INFINITE_SLOTS)
 		xprtargs.flags |= XPRT_CREATE_INFINITE_SLOTS;
 	if (args->flags & RPC_CLNT_CREATE_NO_IDLE_TIMEOUT)
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index f5572e31d518..4f01f63102ee 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -136,6 +136,8 @@ static void svc_xprt_free(struct kref *kref)
 	/* See comment on corresponding get in xs_setup_bc_tcp(): */
 	if (xprt->xpt_bc_xprt)
 		xprt_put(xprt->xpt_bc_xprt);
+	if (xprt->xpt_bc_xps)
+		xprt_switch_put(xprt->xpt_bc_xps);
 	xprt->xpt_ops->xpo_free(xprt);
 	module_put(owner);
 }
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 2d3e0c42361e..7e2b2fa189c3 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -3057,6 +3057,7 @@ static struct rpc_xprt *xs_setup_bc_tcp(struct xprt_create *args)
 		return xprt;
 
 	args->bc_xprt->xpt_bc_xprt = NULL;
+	args->bc_xprt->xpt_bc_xps = NULL;
 	xprt_put(xprt);
 	ret = ERR_PTR(-EINVAL);
 out_err: