[PATCH 09/17] staging: lustre: ldlm: use delayed_work for pools_recalc

From: NeilBrown
Date: Thu Mar 01 2018 - 18:33:28 EST


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@xxxxxxxx>
---
drivers/staging/lustre/lustre/ldlm/ldlm_pool.c | 99 +++---------------------
1 file changed, 11 insertions(+), 88 deletions(-)

diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c b/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c
index a0e486b57e08..53b8f33e54b5 100644
--- 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();
}