[RFC PATCH 1/5] md: add helpers for requested sync action

From: Zheng Qixing <[email protected]>

Add helpers for handling requested sync action.

In handle_requested_sync_action(), add mutual exclusivity checks between
check/repair operations. This prevents the scenario where one operation
is requested, but before MD_RECOVERY_RUNNING is set, another operation is
requested, resulting in neither an EBUSY return nor proper execution of
the second operation.

Signed-off-by: Zheng Qixing <[email protected]>
---
 drivers/md/md.c | 87 +++++++++++++++++++++++++++++++++++++------------
 1 file changed, 66 insertions(+), 21 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 5df2220b1bd1..ccaa2e6fe079 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -665,6 +665,59 @@ void mddev_put(struct mddev *mddev)
 	spin_unlock(&all_mddevs_lock);
 }
 
+static int __handle_requested_sync_action(struct mddev *mddev,
+					  enum sync_action action)
+{
+	switch (action) {
+	case ACTION_CHECK:
+		set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+		fallthrough;
+	case ACTION_REPAIR:
+		set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
+		set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int handle_requested_sync_action(struct mddev *mddev,
+					enum sync_action action)
+{
+	if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
+		return -EBUSY;
+	return __handle_requested_sync_action(mddev, action);
+}
+
+static enum sync_action __get_recovery_sync_action(struct mddev *mddev)
+{
+	if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
+		return ACTION_CHECK;
+	if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
+		return ACTION_REPAIR;
+	return ACTION_RESYNC;
+}
+
+static enum sync_action get_recovery_sync_action(struct mddev *mddev)
+{
+	return __get_recovery_sync_action(mddev);
+}
+
+static void init_recovery_position(struct mddev *mddev)
+{
+	mddev->resync_min = 0;
+}
+
+static void set_requested_position(struct mddev *mddev, sector_t value)
+{
+	mddev->resync_min = value;
+}
+
+static sector_t get_requested_position(struct mddev *mddev)
+{
+	return mddev->resync_min;
+}
+
 static void md_safemode_timeout(struct timer_list *t);
 static void md_start_sync(struct work_struct *ws);
 
@@ -781,7 +834,7 @@ int mddev_init(struct mddev *mddev)
 	mddev->reshape_position = MaxSector;
 	mddev->reshape_backwards = 0;
 	mddev->last_sync_action = ACTION_IDLE;
-	mddev->resync_min = 0;
+	init_recovery_position(mddev);
 	mddev->resync_max = MaxSector;
 	mddev->level = LEVEL_NONE;
 
@@ -5101,17 +5154,9 @@ enum sync_action md_sync_action(struct mddev *mddev)
 	if (test_bit(MD_RECOVERY_RECOVER, &recovery))
 		return ACTION_RECOVER;
 
-	if (test_bit(MD_RECOVERY_SYNC, &recovery)) {
-		/*
-		 * MD_RECOVERY_CHECK must be paired with
-		 * MD_RECOVERY_REQUESTED.
-		 */
-		if (test_bit(MD_RECOVERY_CHECK, &recovery))
-			return ACTION_CHECK;
-		if (test_bit(MD_RECOVERY_REQUESTED, &recovery))
-			return ACTION_REPAIR;
-		return ACTION_RESYNC;
-	}
+	/* MD_RECOVERY_CHECK must be paired with MD_RECOVERY_REQUESTED. */
+	if (test_bit(MD_RECOVERY_SYNC, &recovery))
+		return get_recovery_sync_action(mddev);
 
 	/*
 	 * MD_RECOVERY_NEEDED or MD_RECOVERY_RUNNING is set, however, no
@@ -5300,11 +5345,10 @@ action_store(struct mddev *mddev, const char *page, size_t len)
 			set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
 			break;
 		case ACTION_CHECK:
-			set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
-			fallthrough;
 		case ACTION_REPAIR:
-			set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
-			set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+			ret = handle_requested_sync_action(mddev, action);
+			if (ret)
+				goto out;
 			fallthrough;
 		case ACTION_RESYNC:
 		case ACTION_IDLE:
@@ -6783,7 +6827,7 @@ static void md_clean(struct mddev *mddev)
 	mddev->dev_sectors = 0;
 	mddev->raid_disks = 0;
 	mddev->resync_offset = 0;
-	mddev->resync_min = 0;
+	init_recovery_position(mddev);
 	mddev->resync_max = MaxSector;
 	mddev->reshape_position = MaxSector;
 	/* we still need mddev->external in export_rdev, do not clear it yet */
@@ -9370,7 +9414,7 @@ static sector_t md_sync_position(struct mddev *mddev, enum sync_action action)
 	switch (action) {
 	case ACTION_CHECK:
 	case ACTION_REPAIR:
-		return mddev->resync_min;
+		return get_requested_position(mddev);
 	case ACTION_RESYNC:
 		if (!mddev->bitmap)
 			return mddev->resync_offset;
@@ -9795,10 +9839,11 @@ void md_do_sync(struct md_thread *thread)
 	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
 		/* We completed so min/max setting can be forgotten if used. */
 		if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
-			mddev->resync_min = 0;
+			set_requested_position(mddev, 0);
 		mddev->resync_max = MaxSector;
-	} else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
-		mddev->resync_min = mddev->curr_resync_completed;
+	} else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
+		set_requested_position(mddev, mddev->curr_resync_completed);
+	}
 	set_bit(MD_RECOVERY_DONE, &mddev->recovery);
 	mddev->curr_resync = MD_RESYNC_NONE;
 	spin_unlock(&mddev->lock);
-- 
2.39.2