sunrpc: Add a sysfs files for rpc_clnt information

These files display useful information about the RPC client, such as the
rpc version number, program name, and maximum number of connections
allowed.

Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
Link: https://lore.kernel.org/r/20250207204225.594002-4-anna@kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

diff --git a/net/sunrpc/sysfs.c b/net/sunrpc/sysfs.c
index dc3b7cd70000cf551edcc44fabd500147f4e3e6f..dcd579eab50af0afac68ee18c69c46be05cbc5af 100644 (file)
--- a/net/sunrpc/sysfs.c
+++ b/net/sunrpc/sysfs.c
@@ -59,6 +59,16 @@ static struct kobject *rpc_sysfs_object_alloc(const char *name,
        return NULL;
 }
 
+static inline struct rpc_clnt *
+rpc_sysfs_client_kobj_get_clnt(struct kobject *kobj)
+{
+       struct rpc_sysfs_client *c = container_of(kobj,
+               struct rpc_sysfs_client, kobject);
+       struct rpc_clnt *ret = c->clnt;
+
+       return refcount_inc_not_zero(&ret->cl_count) ? ret : NULL;
+}
+
 static inline struct rpc_xprt *
 rpc_sysfs_xprt_kobj_get_xprt(struct kobject *kobj)
 {
@@ -86,6 +96,51 @@ rpc_sysfs_xprt_switch_kobj_get_xprt(struct kobject *kobj)
        return xprt_switch_get(x->xprt_switch);
 }
 
+static ssize_t rpc_sysfs_clnt_version_show(struct kobject *kobj,
+                                          struct kobj_attribute *attr,
+                                          char *buf)
+{
+       struct rpc_clnt *clnt = rpc_sysfs_client_kobj_get_clnt(kobj);
+       ssize_t ret;
+
+       if (!clnt)
+               return sprintf(buf, "<closed>\n");
+
+       ret = sprintf(buf, "%u", clnt->cl_vers);
+       refcount_dec(&clnt->cl_count);
+       return ret;
+}
+
+static ssize_t rpc_sysfs_clnt_program_show(struct kobject *kobj,
+                                          struct kobj_attribute *attr,
+                                          char *buf)
+{
+       struct rpc_clnt *clnt = rpc_sysfs_client_kobj_get_clnt(kobj);
+       ssize_t ret;
+
+       if (!clnt)
+               return sprintf(buf, "<closed>\n");
+
+       ret = sprintf(buf, "%s", clnt->cl_program->name);
+       refcount_dec(&clnt->cl_count);
+       return ret;
+}
+
+static ssize_t rpc_sysfs_clnt_max_connect_show(struct kobject *kobj,
+                                              struct kobj_attribute *attr,
+                                              char *buf)
+{
+       struct rpc_clnt *clnt = rpc_sysfs_client_kobj_get_clnt(kobj);
+       ssize_t ret;
+
+       if (!clnt)
+               return sprintf(buf, "<closed>\n");
+
+       ret = sprintf(buf, "%u\n", clnt->cl_max_connect);
+       refcount_dec(&clnt->cl_count);
+       return ret;
+}
+
 static ssize_t rpc_sysfs_xprt_dstaddr_show(struct kobject *kobj,
                                           struct kobj_attribute *attr,
                                           char *buf)
@@ -423,6 +478,23 @@ static const void *rpc_sysfs_xprt_namespace(const struct kobject *kobj)
                            kobject)->xprt->xprt_net;
 }
 
+static struct kobj_attribute rpc_sysfs_clnt_version = __ATTR(rpc_version,
+       0444, rpc_sysfs_clnt_version_show, NULL);
+
+static struct kobj_attribute rpc_sysfs_clnt_program = __ATTR(program,
+       0444, rpc_sysfs_clnt_program_show, NULL);
+
+static struct kobj_attribute rpc_sysfs_clnt_max_connect = __ATTR(max_connect,
+       0444, rpc_sysfs_clnt_max_connect_show, NULL);
+
+static struct attribute *rpc_sysfs_rpc_clnt_attrs[] = {
+       &rpc_sysfs_clnt_version.attr,
+       &rpc_sysfs_clnt_program.attr,
+       &rpc_sysfs_clnt_max_connect.attr,
+       NULL,
+};
+ATTRIBUTE_GROUPS(rpc_sysfs_rpc_clnt);
+
 static struct kobj_attribute rpc_sysfs_xprt_dstaddr = __ATTR(dstaddr,
        0644, rpc_sysfs_xprt_dstaddr_show, rpc_sysfs_xprt_dstaddr_store);
 
@@ -459,6 +531,7 @@ ATTRIBUTE_GROUPS(rpc_sysfs_xprt_switch);
 
 static const struct kobj_type rpc_sysfs_client_type = {
        .release = rpc_sysfs_client_release,
+       .default_groups = rpc_sysfs_rpc_clnt_groups,
        .sysfs_ops = &kobj_sysfs_ops,
        .namespace = rpc_sysfs_client_namespace,
 };