[RFC v2 2/5] md: serialize requested sync actions and clear stale request state

From: Zheng Qixing <[email protected]>

In handle_requested_sync_action(), return -EBUSY when
MD_RECOVERY_REQUESTED is already set. This serializes requested sync
actions (such as check or repair) and avoids a race window where a
second sync request can be issued before MD_RECOVERY_RUNNING is set,
resulting in the later request being neither rejected nor executed.

Additionally, in md_check_recovery(), clear requested-sync related
state bits when no recovery operation is running. This prevents stale
request state from persisting in cases where a sync action is queued
and 'frozen' is written before MD_RECOVERY_RUNNING is set, which would
cause subsequent sync requests to spuriously fail with -EBUSY.

Signed-off-by: Zheng Qixing <[email protected]>
---
 drivers/md/md.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 84af578876e2..7fe02ee21d3e 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -668,6 +668,9 @@ void mddev_put(struct mddev *mddev)
 static int handle_requested_sync_action(struct mddev *mddev,
 					enum sync_action action)
 {
+	if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
+		return -EBUSY;
+
 	switch (action) {
 	case ACTION_CHECK:
 		set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
@@ -10318,6 +10321,9 @@ void md_check_recovery(struct mddev *mddev)
 			queue_work(md_misc_wq, &mddev->sync_work);
 		} else {
 			clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+			clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+			clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
+			clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
 			wake_up(&resync_wait);
 		}
 
-- 
2.39.2