raid5-cache: suspend reclaim thread instead of shutdown

There is mechanism to suspend a kernel thread. Use it instead of playing
create/destroy game.

Signed-off-by: Shaohua Li <shli@fb.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Cc: Song Liu <songliubraving@fb.com>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 62f3fb9..297757a 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -7187,10 +7187,12 @@ static int md_thread(void *arg)
                wait_event_interruptible_timeout
                        (thread->wqueue,
                         test_bit(THREAD_WAKEUP, &thread->flags)
-                        || kthread_should_stop(),
+                        || kthread_should_stop() || kthread_should_park(),
                         thread->timeout);
 
                clear_bit(THREAD_WAKEUP, &thread->flags);
+               if (kthread_should_park())
+                       kthread_parkme();
                if (!kthread_should_stop())
                        thread->run(thread);
        }

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 8cb79fc..5f817bd 100644 (file)
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -19,6 +19,7 @@
 #include <linux/raid/md_p.h>
 #include <linux/crc32c.h>
 #include <linux/random.h>
+#include <linux/kthread.h>
 #include "md.h"
 #include "raid5.h"
 #include "bitmap.h"
@@ -1437,23 +1438,14 @@ void r5l_quiesce(struct r5l_log *log, int state)
        struct mddev *mddev;
        if (!log || state == 2)
                return;
-       if (state == 0) {
-               /*
-                * This is a special case for hotadd. In suspend, the array has
-                * no journal. In resume, journal is initialized as well as the
-                * reclaim thread.
-                */
-               if (log->reclaim_thread)
-                       return;
-               log->reclaim_thread = md_register_thread(r5l_reclaim_thread,
-                                       log->rdev->mddev, "reclaim");
-               log->reclaim_thread->timeout = R5C_RECLAIM_WAKEUP_INTERVAL;
-       } else if (state == 1) {
+       if (state == 0)
+               kthread_unpark(log->reclaim_thread->tsk);
+       else if (state == 1) {
                /* make sure r5l_write_super_and_discard_space exits */
                mddev = log->rdev->mddev;
                wake_up(&mddev->sb_wait);
+               kthread_park(log->reclaim_thread->tsk);
                r5l_wake_reclaim(log, MaxSector);
-               md_unregister_thread(&log->reclaim_thread);
                r5l_do_reclaim(log);
        }
 }