svc: Add /proc/sys/sunrpc/transport files

Add a file that when read lists the set of registered svc
transports.

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, 60 insertions, 0 deletions

diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h
index 405281e745d1..01e71b7a2e20 100644
--- a/include/linux/sunrpc/svc_xprt.h
+++ b/include/linux/sunrpc/svc_xprt.h
@@ -79,6 +79,7 @@ void	svc_xprt_copy_addrs(struct svc_rqst *rqstp, struct svc_xprt *xprt);
 void    svc_close_xprt(struct svc_xprt *xprt);
 void    svc_delete_xprt(struct svc_xprt *xprt);
 int     svc_port_is_privileged(struct sockaddr *sin);
+int     svc_print_xprts(char *buf, int maxlen);
 
 static inline void svc_xprt_get(struct svc_xprt *xprt)
 {
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 000c7dc3b82c..2e5b92ae24ed 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -112,6 +112,34 @@ void svc_unreg_xprt_class(struct svc_xprt_class *xcl)
 }
 EXPORT_SYMBOL_GPL(svc_unreg_xprt_class);
 
+/*
+ * Format the transport list for printing
+ */
+int svc_print_xprts(char *buf, int maxlen)
+{
+        struct list_head *le;
+        char tmpstr[80];
+        int len = 0;
+        buf[0] = '\0';
+
+        spin_lock(&svc_xprt_class_lock);
+        list_for_each(le, &svc_xprt_class_list) {
+                int slen;
+                struct svc_xprt_class *xcl =
+                        list_entry(le, struct svc_xprt_class, xcl_list);
+
+                sprintf(tmpstr, "%s %d\n", xcl->xcl_name, xcl->xcl_max_payload);
+                slen = strlen(tmpstr);
+                if (len + slen > maxlen)
+                        break;
+                len += slen;
+                strcat(buf, tmpstr);
+        }
+        spin_unlock(&svc_xprt_class_lock);
+
+        return len;
+}
+
 static void svc_xprt_free(struct kref *kref)
 {
         struct svc_xprt *xprt =
diff --git a/net/sunrpc/sysctl.c b/net/sunrpc/sysctl.c
index bada7de0c2fc..0f8c439b848a 100644
--- a/net/sunrpc/sysctl.c
+++ b/net/sunrpc/sysctl.c
@@ -18,6 +18,7 @@
 #include <linux/sunrpc/types.h>
 #include <linux/sunrpc/sched.h>
 #include <linux/sunrpc/stats.h>
+#include <linux/sunrpc/svc_xprt.h>
 
 /*
  * Declare the debug flags here
@@ -55,6 +56,30 @@ rpc_unregister_sysctl(void)
         }
 }
 
+static int proc_do_xprt(ctl_table *table, int write, struct file *file,
+                        void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+        char tmpbuf[256];
+        int len;
+        if ((*ppos && !write) || !*lenp) {
+                *lenp = 0;
+                return 0;
+        }
+        if (write)
+                return -EINVAL;
+        else {
+                len = svc_print_xprts(tmpbuf, sizeof(tmpbuf));
+                if (!access_ok(VERIFY_WRITE, buffer, len))
+                        return -EFAULT;
+
+                if (__copy_to_user(buffer, tmpbuf, len))
+                        return -EFAULT;
+        }
+        *lenp -= len;
+        *ppos += len;
+        return 0;
+}
+
 static int
 proc_dodebug(ctl_table *table, int write, struct file *file,
                                 void __user *buffer, size_t *lenp, loff_t *ppos)
@@ -147,6 +172,12 @@ static ctl_table debug_table[] = {
                 .mode           = 0644,
                 .proc_handler   = &proc_dodebug
         },
+        {
+                .procname       = "transports",
+                .maxlen         = 256,
+                .mode           = 0444,
+                .proc_handler   = &proc_do_xprt,
+        },
         { .ctl_name = 0 }
 };