nfsd: new netlink ops to get/set server pool_mode

Signed-off-by: Jeff Layton <[e-mail]>
Signed-off-by: Chuck Lever <[e-mail]>

Documentation/netlink/specs/nfsd.yaml

···
         type: nest
         nested-attributes: sock
         multi-attr: true
+  -
+    name: pool-mode
+    attributes:
+      -
+        name: mode
+        type: string
+      -
+        name: npools
+        type: u32
 
 operations:
   list:
···
         reply:
           attributes:
             - addr
+    -
+      name: pool-mode-set
+      doc: set the current server pool-mode
+      attribute-set: pool-mode
+      flags: [ admin-perm ]
+      do:
+        request:
+          attributes:
+            - mode
+    -
+      name: pool-mode-get
+      doc: get info about server pool-mode
+      attribute-set: pool-mode
+      do:
+        reply:
+          attributes:
+            - mode
+            - npools

fs/nfsd/netlink.c

···
 	[NFSD_A_SERVER_SOCK_ADDR] = NLA_POLICY_NESTED(nfsd_sock_nl_policy),
 };
 
+/* NFSD_CMD_POOL_MODE_SET - do */
+static const struct nla_policy nfsd_pool_mode_set_nl_policy[NFSD_A_POOL_MODE_MODE + 1] = {
+	[NFSD_A_POOL_MODE_MODE] = { .type = NLA_NUL_STRING, },
+};
+
 /* Ops table for nfsd */
 static const struct genl_split_ops nfsd_nl_ops[] = {
 	{
···
 	{
 		.cmd	= NFSD_CMD_LISTENER_GET,
 		.doit	= nfsd_nl_listener_get_doit,
+		.flags	= GENL_CMD_CAP_DO,
+	},
+	{
+		.cmd		= NFSD_CMD_POOL_MODE_SET,
+		.doit		= nfsd_nl_pool_mode_set_doit,
+		.policy		= nfsd_pool_mode_set_nl_policy,
+		.maxattr	= NFSD_A_POOL_MODE_MODE,
+		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
+	},
+	{
+		.cmd	= NFSD_CMD_POOL_MODE_GET,
+		.doit	= nfsd_nl_pool_mode_get_doit,
 		.flags	= GENL_CMD_CAP_DO,
 	},
 };

fs/nfsd/netlink.h

···
 int nfsd_nl_version_get_doit(struct sk_buff *skb, struct genl_info *info);
 int nfsd_nl_listener_set_doit(struct sk_buff *skb, struct genl_info *info);
 int nfsd_nl_listener_get_doit(struct sk_buff *skb, struct genl_info *info);
+int nfsd_nl_pool_mode_set_doit(struct sk_buff *skb, struct genl_info *info);
+int nfsd_nl_pool_mode_get_doit(struct sk_buff *skb, struct genl_info *info);
 
 extern struct genl_family nfsd_nl_family;
 

fs/nfsd/nfsctl.c

···
 }
 
 /**
+ * nfsd_nl_pool_mode_set_doit - set the number of running threads
+ * @skb: reply buffer
+ * @info: netlink metadata and command arguments
+ *
+ * Return 0 on success or a negative errno.
+ */
+int nfsd_nl_pool_mode_set_doit(struct sk_buff *skb, struct genl_info *info)
+{
+	const struct nlattr *attr;
+
+	if (GENL_REQ_ATTR_CHECK(info, NFSD_A_POOL_MODE_MODE))
+		return -EINVAL;
+
+	attr = info->attrs[NFSD_A_POOL_MODE_MODE];
+	return sunrpc_set_pool_mode(nla_data(attr));
+}
+
+/**
+ * nfsd_nl_pool_mode_get_doit - get info about pool_mode
+ * @skb: reply buffer
+ * @info: netlink metadata and command arguments
+ *
+ * Return 0 on success or a negative errno.
+ */
+int nfsd_nl_pool_mode_get_doit(struct sk_buff *skb, struct genl_info *info)
+{
+	struct net *net = genl_info_net(info);
+	char buf[16];
+	void *hdr;
+	int err;
+
+	if (sunrpc_get_pool_mode(buf, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf))
+		return -ERANGE;
+
+	skb = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!skb)
+		return -ENOMEM;
+
+	err = -EMSGSIZE;
+	hdr = genlmsg_iput(skb, info);
+	if (!hdr)
+		goto err_free_msg;
+
+	err = nla_put_string(skb, NFSD_A_POOL_MODE_MODE, buf) |
+	      nla_put_u32(skb, NFSD_A_POOL_MODE_NPOOLS, nfsd_nrpools(net));
+	if (err)
+		goto err_free_msg;
+
+	genlmsg_end(skb, hdr);
+	return genlmsg_reply(skb, info);
+
+err_free_msg:
+	nlmsg_free(skb);
+	return err;
+}
+
+/**
  * nfsd_net_init - Prepare the nfsd_net portion of a new net namespace
  * @net: a freshly-created network namespace
  *

include/uapi/linux/nfsd_netlink.h

···
 };
 
 enum {
+	NFSD_A_POOL_MODE_MODE = 1,
+	NFSD_A_POOL_MODE_NPOOLS,
+
+	__NFSD_A_POOL_MODE_MAX,
+	NFSD_A_POOL_MODE_MAX = (__NFSD_A_POOL_MODE_MAX - 1)
+};
+
+enum {
 	NFSD_CMD_RPC_STATUS_GET = 1,
 	NFSD_CMD_THREADS_SET,
 	NFSD_CMD_THREADS_GET,
···
 	NFSD_CMD_VERSION_GET,
 	NFSD_CMD_LISTENER_SET,
 	NFSD_CMD_LISTENER_GET,
+	NFSD_CMD_POOL_MODE_SET,
+	NFSD_CMD_POOL_MODE_GET,
 
 	__NFSD_CMD_MAX,
 	NFSD_CMD_MAX = (__NFSD_CMD_MAX - 1)