+/**
+ * write_versions - Set or report the available NFS protocol versions
+ *
+ * Input:
+ * buf: ignored
+ * size: zero
+ * Output:
+ * On success: passed-in buffer filled with '\n'-terminated C
+ * string containing positive or negative integer
+ * values representing the current status of each
+ * protocol version;
+ * return code is the size in bytes of the string
+ * On error: return code is zero or a negative errno value
+ *
+ * OR
+ *
+ * Input:
+ * buf: C string containing whitespace-
+ * separated positive or negative
+ * integer values representing NFS
+ * protocol versions to enable ("+n")
+ * or disable ("-n")
+ * size: non-zero length of C string in @buf
+ * Output:
+ * On success: status of zero or more protocol versions has
+ * been updated; passed-in buffer filled with
+ * '\n'-terminated C string containing positive
+ * or negative integer values representing the
+ * current status of each protocol version;
+ * return code is the size in bytes of the string
+ * On error: return code is zero or a negative errno value
+ */
+static ssize_t write_versions(struct file *file, char *buf, size_t size)
+{
+ ssize_t rv;
+
+ mutex_lock(&nfsd_mutex);
+ rv = __write_versions(file, buf, size);
+ mutex_unlock(&nfsd_mutex);
+ return rv;
+}
+
+/*
+ * Zero-length write. Return a list of NFSD's current listener
+ * transports.
+ */
+static ssize_t __write_ports_names(char *buf)
+{
+ if (nfsd_serv == NULL)
+ return 0;
+ return svc_xprt_names(nfsd_serv, buf, SIMPLE_TRANSACTION_LIMIT);
+}
+
+/*
+ * A single 'fd' number was written, in which case it must be for
+ * a socket of a supported family/protocol, and we use it as an
+ * nfsd listener.
+ */
+static ssize_t __write_ports_addfd(char *buf)
+{
+ char *mesg = buf;
+ int fd, err;
+
+ err = get_int(&mesg, &fd);
+ if (err != 0 || fd < 0)
+ return -EINVAL;
+
+ err = nfsd_create_serv();
+ if (err != 0)
+ return err;
+
+ err = lockd_up();
+ if (err != 0)
+ goto out;
+
+ err = svc_addsock(nfsd_serv, fd, buf);
+ if (err < 0)
+ lockd_down();
+
+out:
+ /* Decrease the count, but don't shut down the service */
+ nfsd_serv->sv_nrthreads--;
+ return err;
+}
+
+/*
+ * A '-' followed by the 'name' of a socket means we close the socket.
+ */
+static ssize_t __write_ports_delfd(char *buf)
+{
+ char *toclose;
+ int len = 0;
+
+ toclose = kstrdup(buf + 1, GFP_KERNEL);
+ if (toclose == NULL)
+ return -ENOMEM;
+
+ if (nfsd_serv != NULL)
+ len = svc_sock_names(buf, nfsd_serv, toclose);
+ if (len >= 0)
+ lockd_down();
+
+ kfree(toclose);
+ return len;
+}
+
+/*
+ * A transport listener is added by writing it's transport name and
+ * a port number.
+ */
+static ssize_t __write_ports_addxprt(char *buf)
+{
+ char transport[16];
+ int port, err;
+
+ if (sscanf(buf, "%15s %4u", transport, &port) != 2)
+ return -EINVAL;
+
+ if (port < 1 || port > USHORT_MAX)
+ return -EINVAL;
+
+ err = nfsd_create_serv();
+ if (err != 0)
+ return err;
+
+ err = svc_create_xprt(nfsd_serv, transport,
+ PF_INET, port, SVC_SOCK_ANONYMOUS);
+ if (err < 0) {
+ /* Give a reasonable perror msg for bad transport string */
+ if (err == -ENOENT)
+ err = -EPROTONOSUPPORT;
+ return err;
+ }
+ return 0;
+}
+
+/*
+ * A transport listener is removed by writing a "-", it's transport
+ * name, and it's port number.
+ */
+static ssize_t __write_ports_delxprt(char *buf)
+{
+ struct svc_xprt *xprt;
+ char transport[16];
+ int port;
+
+ if (sscanf(&buf[1], "%15s %4u", transport, &port) != 2)
+ return -EINVAL;
+
+ if (port < 1 || port > USHORT_MAX || nfsd_serv == NULL)
+ return -EINVAL;
+
+ xprt = svc_find_xprt(nfsd_serv, transport, AF_UNSPEC, port);
+ if (xprt == NULL)
+ return -ENOTCONN;
+
+ svc_close_xprt(xprt);
+ svc_xprt_put(xprt);
+ return 0;
+}
+
+static ssize_t __write_ports(struct file *file, char *buf, size_t size)
+{
+ if (size == 0)
+ return __write_ports_names(buf);
+
+ if (isdigit(buf[0]))
+ return __write_ports_addfd(buf);
+
+ if (buf[0] == '-' && isdigit(buf[1]))
+ return __write_ports_delfd(buf);
+
+ if (isalpha(buf[0]))
+ return __write_ports_addxprt(buf);
+
+ if (buf[0] == '-' && isalpha(buf[1]))
+ return __write_ports_delxprt(buf);
+
+ return -EINVAL;
+}
+
+/**
+ * write_ports - Pass a socket file descriptor or transport name to listen on
+ *
+ * Input:
+ * buf: ignored
+ * size: zero
+ * Output:
+ * On success: passed-in buffer filled with a '\n'-terminated C
+ * string containing a whitespace-separated list of
+ * named NFSD listeners;
+ * return code is the size in bytes of the string
+ * On error: return code is zero or a negative errno value
+ *
+ * OR
+ *
+ * Input:
+ * buf: C string containing an unsigned
+ * integer value representing a bound
+ * but unconnected socket that is to be
+ * used as an NFSD listener; listen(3)
+ * must be called for a SOCK_STREAM
+ * socket, otherwise it is ignored
+ * size: non-zero length of C string in @buf
+ * Output:
+ * On success: NFS service is started;
+ * passed-in buffer filled with a '\n'-terminated C
+ * string containing a unique alphanumeric name of
+ * the listener;
+ * return code is the size in bytes of the string
+ * On error: return code is a negative errno value
+ *
+ * OR
+ *
+ * Input:
+ * buf: C string containing a "-" followed
+ * by an integer value representing a
+ * previously passed in socket file
+ * descriptor
+ * size: non-zero length of C string in @buf
+ * Output:
+ * On success: NFS service no longer listens on that socket;
+ * passed-in buffer filled with a '\n'-terminated C
+ * string containing a unique name of the listener;
+ * return code is the size in bytes of the string
+ * On error: return code is a negative errno value
+ *
+ * OR
+ *
+ * Input:
+ * buf: C string containing a transport
+ * name and an unsigned integer value
+ * representing the port to listen on,
+ * separated by whitespace
+ * size: non-zero length of C string in @buf
+ * Output:
+ * On success: returns zero; NFS service is started
+ * On error: return code is a negative errno value
+ *
+ * OR
+ *
+ * Input:
+ * buf: C string containing a "-" followed
+ * by a transport name and an unsigned
+ * integer value representing the port
+ * to listen on, separated by whitespace
+ * size: non-zero length of C string in @buf
+ * Output:
+ * On success: returns zero; NFS service no longer listens
+ * on that transport
+ * On error: return code is a negative errno value
+ */
+static ssize_t write_ports(struct file *file, char *buf, size_t size)
+{
+ ssize_t rv;
+
+ mutex_lock(&nfsd_mutex);
+ rv = __write_ports(file, buf, size);
+ mutex_unlock(&nfsd_mutex);
+ return rv;
+}
+
+
+int nfsd_max_blksize;
+
+/**
+ * write_maxblksize - Set or report the current NFS blksize
+ *
+ * Input:
+ * buf: ignored
+ * size: zero
+ *
+ * OR
+ *
+ * Input:
+ * buf: C string containing an unsigned
+ * integer value representing the new
+ * NFS blksize
+ * size: non-zero length of C string in @buf
+ * Output:
+ * On success: passed-in buffer filled with '\n'-terminated C string
+ * containing numeric value of the current NFS blksize
+ * setting;
+ * return code is the size in bytes of the string
+ * On error: return code is zero or a negative errno value
+ */
+static ssize_t write_maxblksize(struct file *file, char *buf, size_t size)
+{
+ char *mesg = buf;
+ if (size > 0) {
+ int bsize;
+ int rv = get_int(&mesg, &bsize);
+ if (rv)
+ return rv;
+ /* force bsize into allowed range and
+ * required alignment.
+ */
+ if (bsize < 1024)
+ bsize = 1024;
+ if (bsize > NFSSVC_MAXBLKSIZE)
+ bsize = NFSSVC_MAXBLKSIZE;
+ bsize &= ~(1024-1);
+ mutex_lock(&nfsd_mutex);
+ if (nfsd_serv && nfsd_serv->sv_nrthreads) {
+ mutex_unlock(&nfsd_mutex);
+ return -EBUSY;
+ }
+ nfsd_max_blksize = bsize;
+ mutex_unlock(&nfsd_mutex);
+ }
+ return sprintf(buf, "%d\n", nfsd_max_blksize);
+}
+