NFS: Add a module parameter to set nfs_mountpoint_expiry_timeout

Setting nfs_mountpoint_expiry_timeout() to a negative value stops
mountpoint expiration, while setting it to a positive value restarts
the scheduler.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c
index fe19ae280262aa0e00ebab2830f3c75474f0d720..6b063227e34e9de4cbb52bfcbac46cc0d69b309a 100644 (file)
--- a/fs/nfs/namespace.c
+++ b/fs/nfs/namespace.c
@@ -311,3 +311,53 @@ int nfs_submount(struct fs_context *fc, struct nfs_server *server)
        return nfs_do_submount(fc);
 }
 EXPORT_SYMBOL_GPL(nfs_submount);
+
+static int param_set_nfs_timeout(const char *val, const struct kernel_param *kp)
+{
+       long num;
+       int ret;
+
+       if (!val)
+               return -EINVAL;
+       ret = kstrtol(val, 0, &num);
+       if (ret)
+               return -EINVAL;
+       if (num > 0) {
+               if (num >= INT_MAX / HZ)
+                       num = INT_MAX;
+               else
+                       num *= HZ;
+               *((int *)kp->arg) = num;
+               if (!list_empty(&nfs_automount_list))
+                       mod_delayed_work(system_wq, &nfs_automount_task, num);
+       } else {
+               *((int *)kp->arg) = -1*HZ;
+               cancel_delayed_work(&nfs_automount_task);
+       }
+       return 0;
+}
+
+static int param_get_nfs_timeout(char *buffer, const struct kernel_param *kp)
+{
+       long num = *((int *)kp->arg);
+
+       if (num > 0) {
+               if (num >= INT_MAX - (HZ - 1))
+                       num = INT_MAX / HZ;
+               else
+                       num = (num + (HZ - 1)) / HZ;
+       } else
+               num = -1;
+       return scnprintf(buffer, PAGE_SIZE, "%li\n", num);
+}
+
+static const struct kernel_param_ops param_ops_nfs_timeout = {
+       .set = param_set_nfs_timeout,
+       .get = param_get_nfs_timeout,
+};
+#define param_check_nfs_timeout(name, p) __param_check(name, p, int);
+
+module_param(nfs_mountpoint_expiry_timeout, nfs_timeout, 0644);
+MODULE_PARM_DESC(nfs_mountpoint_expiry_timeout,
+               "Set the NFS automounted mountpoint timeout value (seconds)."
+               "Values <= 0 turn expiration off.");