staging: lustre: ldlm: use delayed_work for pools_recalc

ldlm currenty has a kthread which wakes up every so often
and calls ldlm_pools_recalc().
The thread is started and stopped, but no other external interactions
happen.

This can trivially be replaced by a delayed_work if we have
ldlm_pools_recalc() reschedule the work rather than just report
when to do that.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c b/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c
index a0e486b..53b8f33 100644 (file)
--- a/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c
+++ b/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c
@@ -784,9 +784,6 @@ static int ldlm_pool_granted(struct ldlm_pool *pl)
        return atomic_read(&pl->pl_granted);
 }
 
-static struct ptlrpc_thread *ldlm_pools_thread;
-static struct completion ldlm_pools_comp;
-
 /*
  * count locks from all namespaces (if possible). Returns number of
  * cached locks.
@@ -899,8 +896,12 @@ static unsigned long ldlm_pools_cli_scan(struct shrinker *s,
                               sc->gfp_mask);
 }
 
-static int ldlm_pools_recalc(enum ldlm_side client)
+static void ldlm_pools_recalc(struct work_struct *ws);
+static DECLARE_DELAYED_WORK(ldlm_recalc_pools, ldlm_pools_recalc);
+
+static void ldlm_pools_recalc(struct work_struct *ws)
 {
+       enum ldlm_side client = LDLM_NAMESPACE_CLIENT;
        struct ldlm_namespace *ns;
        struct ldlm_namespace *ns_old = NULL;
        /* seconds of sleep if no active namespaces */
@@ -982,92 +983,19 @@ static int ldlm_pools_recalc(enum ldlm_side client)
        /* Wake up the blocking threads from time to time. */
        ldlm_bl_thread_wakeup();
 
-       return time;
-}
-
-static int ldlm_pools_thread_main(void *arg)
-{
-       struct ptlrpc_thread *thread = (struct ptlrpc_thread *)arg;
-       int c_time;
-
-       thread_set_flags(thread, SVC_RUNNING);
-       wake_up(&thread->t_ctl_waitq);
-
-       CDEBUG(D_DLMTRACE, "%s: pool thread starting, process %d\n",
-              "ldlm_poold", current_pid());
-
-       while (1) {
-               /*
-                * Recal all pools on this tick.
-                */
-               c_time = ldlm_pools_recalc(LDLM_NAMESPACE_CLIENT);
-
-               /*
-                * Wait until the next check time, or until we're
-                * stopped.
-                */
-               wait_event_idle_timeout(thread->t_ctl_waitq,
-                                       thread_is_stopping(thread) ||
-                                       thread_is_event(thread),
-                                       c_time * HZ);
-
-               if (thread_test_and_clear_flags(thread, SVC_STOPPING))
-                       break;
-               thread_test_and_clear_flags(thread, SVC_EVENT);
-       }
-
-       thread_set_flags(thread, SVC_STOPPED);
-       wake_up(&thread->t_ctl_waitq);
-
-       CDEBUG(D_DLMTRACE, "%s: pool thread exiting, process %d\n",
-              "ldlm_poold", current_pid());
-
-       complete_and_exit(&ldlm_pools_comp, 0);
+       schedule_delayed_work(&ldlm_recalc_pools, time * HZ);
 }
 
 static int ldlm_pools_thread_start(void)
 {
-       struct task_struct *task;
-
-       if (ldlm_pools_thread)
-               return -EALREADY;
-
-       ldlm_pools_thread = kzalloc(sizeof(*ldlm_pools_thread), GFP_NOFS);
-       if (!ldlm_pools_thread)
-               return -ENOMEM;
-
-       init_completion(&ldlm_pools_comp);
-       init_waitqueue_head(&ldlm_pools_thread->t_ctl_waitq);
+       schedule_delayed_work(&ldlm_recalc_pools, 0);
 
-       task = kthread_run(ldlm_pools_thread_main, ldlm_pools_thread,
-                          "ldlm_poold");
-       if (IS_ERR(task)) {
-               CERROR("Can't start pool thread, error %ld\n", PTR_ERR(task));
-               kfree(ldlm_pools_thread);
-               ldlm_pools_thread = NULL;
-               return PTR_ERR(task);
-       }
-       wait_event_idle(ldlm_pools_thread->t_ctl_waitq,
-                       thread_is_running(ldlm_pools_thread));
        return 0;
 }
 
 static void ldlm_pools_thread_stop(void)
 {
-       if (!ldlm_pools_thread)
-               return;
-
-       thread_set_flags(ldlm_pools_thread, SVC_STOPPING);
-       wake_up(&ldlm_pools_thread->t_ctl_waitq);
-
-       /*
-        * Make sure that pools thread is finished before freeing @thread.
-        * This fixes possible race and oops due to accessing freed memory
-        * in pools thread.
-        */
-       wait_for_completion(&ldlm_pools_comp);
-       kfree(ldlm_pools_thread);
-       ldlm_pools_thread = NULL;
+       cancel_delayed_work_sync(&ldlm_recalc_pools);
 }
 
 static struct shrinker ldlm_pools_cli_shrinker = {
@@ -1081,20 +1009,15 @@ int ldlm_pools_init(void)
        int rc;
 
        rc = ldlm_pools_thread_start();
-       if (rc)
-               return rc;
-
-       rc = register_shrinker(&ldlm_pools_cli_shrinker);
-       if (rc)
-               ldlm_pools_thread_stop();
+       if (!rc)
+               rc = register_shrinker(&ldlm_pools_cli_shrinker);
 
        return rc;
 }
 
 void ldlm_pools_fini(void)
 {
-       if (ldlm_pools_thread)
-               unregister_shrinker(&ldlm_pools_cli_shrinker);
+       unregister_shrinker(&ldlm_pools_cli_shrinker);
 
        ldlm_pools_thread_stop();
 }