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, 48 insertions, 1 deletions

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;
 }