Add zfs_multihost_interval tunable handler for FreeBSD

This tunable required a handler to be implemented for
ZFS_MODULE_PARAM_CALL.

Add the handler so the tunable can be declared in common code.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes #10490

module/os/freebsd/zfs/sysctl_os.c

@@ -691,3 +691,18 @@ param_set_slop_shift(SYSCTL_HANDLER_ARGS)
 
 	return (0);
 }
+
+int
+param_set_multihost_interval(SYSCTL_HANDLER_ARGS)
+{
+	int err;
+
+	err = sysctl_handle_long(oidp, arg1, 0, req);
+	if (err != 0 || req->newptr == NULL)
+		return (err);
+
+	if (spa_mode_global != SPA_MODE_UNINIT)
+		mmp_signal_all_threads();
+
+	return (0);
+}

module/os/linux/zfs/mmp_os.c

@@ -25,7 +25,7 @@
 #include <sys/zfs_context.h>
 #include <sys/mmp.h>
 
-static int
+int
 param_set_multihost_interval(const char *val, zfs_kernel_param_t *kp)
 {
 	int ret;
@@ -39,8 +39,3 @@ param_set_multihost_interval(const char *val, zfs_kernel_param_t *kp)
 
 	return (ret);
 }
-
-module_param_call(zfs_multihost_interval, param_set_multihost_interval,
-    param_get_ulong, &zfs_multihost_interval, 0644);
-MODULE_PARM_DESC(zfs_multihost_interval,
-	"Milliseconds between mmp writes to each leaf");

module/zfs/mmp.c

@@ -715,6 +715,12 @@ mmp_signal_all_threads(void)
 	mutex_exit(&spa_namespace_lock);
 }
 
+/* BEGIN CSTYLED */
+ZFS_MODULE_PARAM_CALL(zfs_multihost, zfs_multihost_, interval,
+	param_set_multihost_interval, param_get_ulong, ZMOD_RW,
+	"Milliseconds between mmp writes to each leaf");
+/* END CSTYLED */
+
 ZFS_MODULE_PARAM(zfs_multihost, zfs_multihost_, fail_intervals, UINT, ZMOD_RW,
 	"Max allowed period without a successful mmp write");