sunrpc: provide transport info in the sysfs directory

Allow to query transport's attributes. Currently showing following
fields of the rpc_xprt structure: state, last_used, cong, cwnd,
max_reqs, min_reqs, num_reqs, sizes of queues binding, sending,
pending, backlog.

Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

net/sunrpc/sysfs.c

@@ -81,6 +81,27 @@ static ssize_t rpc_sysfs_xprt_dstaddr_show(struct kobject *kobj,
 	return ret + 1;
 }
 
+static ssize_t rpc_sysfs_xprt_info_show(struct kobject *kobj,
+					struct kobj_attribute *attr,
+					char *buf)
+{
+	struct rpc_xprt *xprt = rpc_sysfs_xprt_kobj_get_xprt(kobj);
+	ssize_t ret;
+
+	if (!xprt)
+		return 0;
+
+	ret = sprintf(buf, "last_used=%lu\ncur_cong=%lu\ncong_win=%lu\n"
+		       "max_num_slots=%u\nmin_num_slots=%u\nnum_reqs=%u\n"
+		       "binding_q_len=%u\nsending_q_len=%u\npending_q_len=%u\n"
+		       "backlog_q_len=%u\n", xprt->last_used, xprt->cong,
+		       xprt->cwnd, xprt->max_reqs, xprt->min_reqs,
+		       xprt->num_reqs, xprt->binding.qlen, xprt->sending.qlen,
+		       xprt->pending.qlen, xprt->backlog.qlen);
+	xprt_put(xprt);
+	return ret + 1;
+}
+
 static ssize_t rpc_sysfs_xprt_dstaddr_store(struct kobject *kobj,
 					    struct kobj_attribute *attr,
 					    const char *buf, size_t count)
@@ -205,8 +226,12 @@ static const void *rpc_sysfs_xprt_namespace(struct kobject *kobj)
 static struct kobj_attribute rpc_sysfs_xprt_dstaddr = __ATTR(dstaddr,
 	0644, rpc_sysfs_xprt_dstaddr_show, rpc_sysfs_xprt_dstaddr_store);
 
+static struct kobj_attribute rpc_sysfs_xprt_info = __ATTR(xprt_info,
+	0444, rpc_sysfs_xprt_info_show, NULL);
+
 static struct attribute *rpc_sysfs_xprt_attrs[] = {
 	&rpc_sysfs_xprt_dstaddr.attr,
+	&rpc_sysfs_xprt_info.attr,
 	NULL,
 };