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>

3 files changed, 63 insertions, 6 deletions

diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 470af0138bb5..08226464e563 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;
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 4aba92698581..eff6a6b4c2f6 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -540,7 +540,7 @@ static ssize_t write_ports(struct file *file, char *buf, size_t size)
                 }
                 return err < 0 ? err : 0;
         }
-        if (buf[0] == '-') {
+        if (buf[0] == '-' && isdigit(buf[1])) {
                 char *toclose = kstrdup(buf+1, GFP_KERNEL);
                 int len = 0;
                 if (!toclose)
@@ -554,6 +554,53 @@ static ssize_t write_ports(struct file *file, char *buf, size_t size)
                 kfree(toclose);
                 return len;
         }
+        /*
+         * Add a transport listener by writing it's transport name
+         */
+        if (isalpha(buf[0])) {
+                int err;
+                char transport[16];
+                int port;
+                if (sscanf(buf, "%15s %4d", transport, &port) == 2) {
+                        err = nfsd_create_serv();
+                        if (!err) {
+                                err = svc_create_xprt(nfsd_serv,
+                                                      transport, port,
+                                                      SVC_SOCK_ANONYMOUS);
+                                if (err == -ENOENT)
+                                        /* Give a reasonable perror msg for
+                                         * bad transport string */
+                                        err = -EPROTONOSUPPORT;
+                        }
+                        return err < 0 ? err : 0;
+                }
+        }
+        /*
+         * Remove a transport by writing it's transport name and port number
+         */
+        if (buf[0] == '-' && isalpha(buf[1])) {
+                struct svc_xprt *xprt;
+                int err = -EINVAL;
+                char transport[16];
+                int port;
+                if (sscanf(&buf[1], "%15s %4d", transport, &port) == 2) {
+                        if (port == 0)
+                                return -EINVAL;
+                        lock_kernel();
+                        if (nfsd_serv) {
+                                xprt = svc_find_xprt(nfsd_serv, transport,
+                                                     AF_UNSPEC, port);
+                                if (xprt) {
+                                        svc_close_xprt(xprt);
+                                        svc_xprt_put(xprt);
+                                        err = 0;
+                                } else
+                                        err = -ENOTCONN;
+                        }
+                        unlock_kernel();
+                        return err < 0 ? err : 0;
+                }
+        }
         return -EINVAL;
 }
 
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 512c10fc1a9f..783597343877 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -842,6 +842,7 @@ void svc_close_xprt(struct svc_xprt *xprt)
         clear_bit(XPT_BUSY, &xprt->xpt_flags);
         svc_xprt_put(xprt);
 }
+EXPORT_SYMBOL_GPL(svc_close_xprt);
 
 void svc_close_all(struct list_head *xprt_list)
 {
@@ -1006,6 +1007,7 @@ struct svc_xprt *svc_find_xprt(struct svc_serv *serv, char *xcl_name,
                 if (port && port != svc_xprt_local_port(xprt))
                         continue;
                 found = xprt;
+                svc_xprt_get(xprt);
                 break;
         }
         spin_unlock_bh(&serv->sv_lock);