[PATCH V4 07/13] raid5: cache device quiesce support

[Shaohua Li <shli@xxxxxx>]

In raid array quiesce, we should stop all IO. Existing mechanism stops
IO from upper layer but not IO from cache reclaim. This makes sure
reclaim thread will stop.

Signed-off-by: Shaohua Li <shli@xxxxxx>
---
 drivers/md/raid5-cache.c | 35 +++++++++++++++++++++++++++++++++++
 drivers/md/raid5.c       |  2 ++
 drivers/md/raid5.h       |  1 +
 3 files changed, 38 insertions(+)

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index c5de6dd..35657cd 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -364,6 +364,13 @@ enum {
 	ERROR_FINISH = 2, /* Had an error, cache has no data */
 };
 
+/* device quiescent support */
+enum {
+	QUIESCE_NONE = 0,
+	QUIESCE_START = 1,
+	QUIESCE_END = 2,
+};
+
 #define PAGE_SECTOR_SHIFT (PAGE_SHIFT - 9)
 
 static inline struct r5c_cache *r5l_cache(struct r5l_log *log)
@@ -2324,6 +2331,15 @@ static void r5c_reclaim_thread(struct md_thread *thread)
 		cache->error_state = 0;
 		mddev_resume(cache->mddev);
 	}
+
+	if (cache->quiesce_state == QUIESCE_START) {
+		/* user IO already finished, we just stop reclaim */
+		cache->reclaim_reason = 0;
+		cache->quiesce_state = QUIESCE_END;
+		wake_up(&cache->reclaim_wait);
+		wait_event(cache->reclaim_wait, cache->quiesce_state ==
+			QUIESCE_NONE);
+	}
 }
 
 static void r5c_wake_reclaimer(struct r5c_cache *cache, int reason)
@@ -2339,6 +2355,25 @@ static void r5c_wake_wait_reclaimer(struct r5c_cache *cache, int reason)
 		&cache->reclaim_reason));
 }
 
+void r5c_quiesce(struct r5conf *conf, int state)
+{
+	struct r5c_cache *cache = conf->cache;
+
+	if (!cache || cache->error_state)
+		return;
+	if (state == 1) {
+		/* we choose to flush all data to raid disks, this is a policy */
+		r5c_wake_wait_reclaimer(cache, RECLAIM_FLUSH_ALL);
+		cache->quiesce_state = QUIESCE_START;
+		md_wakeup_thread(cache->reclaim_thread);
+		wait_event(cache->reclaim_wait, cache->quiesce_state ==
+			QUIESCE_END);
+	} else if (state == 0) {
+		cache->quiesce_state = QUIESCE_NONE;
+		wake_up(&cache->reclaim_wait);
+	}
+}
+
 static void r5c_parity_task_end(struct r5l_task *task, int error)
 {
 	struct stripe_head *head_sh = task->private;
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index a9e10ff..bcd6c1f 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7485,6 +7485,7 @@ static void raid5_quiesce(struct mddev *mddev, int state)
 		break;
 
 	case 1: /* stop all writes */
+		r5c_quiesce(conf, state);
 		lock_all_device_hash_locks_irq(conf);
 		/* '2' tells resync/reshape to pause so that all
 		 * active stripes can drain
@@ -7507,6 +7508,7 @@ static void raid5_quiesce(struct mddev *mddev, int state)
 		wake_up(&conf->wait_for_stripe);
 		wake_up(&conf->wait_for_overlap);
 		unlock_all_device_hash_locks_irq(conf);
+		r5c_quiesce(conf, state);
 		break;
 	}
 }
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 16bd54f..534e5be 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -617,4 +617,5 @@ struct r5c_cache *r5c_init_cache(struct r5conf *conf, struct md_rdev *rdev);
 void r5c_exit_cache(struct r5c_cache *cache);
 void r5c_write_start(struct mddev *mddev, struct bio *bi);
 void r5c_write_end(struct mddev *mddev, struct bio *bi);
+void r5c_quiesce(struct r5conf *conf, int state);
 #endif
-- 
1.8.1

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