knfsd: Support adding transports by writing portlist file

Update the write handler for the portlist file to allow creating new
listening endpoints on a transport. The general form of the string is:

<transport_name><space><port number>

For example:

echo "tcp 2049" > /proc/fs/nfsd/portlist

This is intended to support the creation of a listening endpoint for
RDMA transports without adding #ifdef code to the nfssvc.c file.

Transports can also be removed as follows:

'-'<transport_name><space><port number>

For example:

echo "-tcp 2049" > /proc/fs/nfsd/portlist

Attempting to add a listener with an invalid transport string results
in EPROTONOSUPPORT and a perror string of "Protocol not supported".

Attempting to remove an non-existent listener (.e.g. bad proto or port)
results in ENOTCONN and a perror string of
"Transport endpoint is not connected"

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Acked-by: Neil Brown <neilb@suse.de>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Greg Banks <gnb@sgi.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 13 insertions, 5 deletions

diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 470af01..0822646 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -227,17 +227,25 @@ lockd(struct svc_rqst *rqstp)
 static int make_socks(struct svc_serv *serv, int proto)
 {
 	static int warned;
+	struct svc_xprt *xprt;
 	int err = 0;
 
-	if (proto == IPPROTO_UDP || nlm_udpport)
-		if (!svc_find_xprt(serv, "udp", 0, 0))
+	if (proto == IPPROTO_UDP || nlm_udpport) {
+		xprt = svc_find_xprt(serv, "udp", 0, 0);
+		if (!xprt)
 			err = svc_create_xprt(serv, "udp", nlm_udpport,
 					      SVC_SOCK_DEFAULTS);
-	if (err >= 0 && (proto == IPPROTO_TCP || nlm_tcpport))
-		if (!svc_find_xprt(serv, "tcp", 0, 0))
+		else
+			svc_xprt_put(xprt);
+	}
+	if (err >= 0 && (proto == IPPROTO_TCP || nlm_tcpport)) {
+		xprt = svc_find_xprt(serv, "tcp", 0, 0);
+		if (!xprt)
 			err = svc_create_xprt(serv, "tcp", nlm_tcpport,
 					      SVC_SOCK_DEFAULTS);
-
+		else
+			svc_xprt_put(xprt);
+	}
 	if (err >= 0) {
 		warned = 0;
 		err = 0;