md: factor out sync completion update into helper

Repeatedly reading 'mddev->recovery' flags in md_do_sync() may introduce
potential risk if this flag is modified during sync, leading to incorrect
offset updates. Therefore, replace direct 'mddev->recovery' checks with
'action'.

Move sync completion update logic into helper md_finish_sync(), which
improves readability and maintainability.

The reshape completion update remains safe as it only updated after
successful reshape when MD_RECOVERY_INTR is not set and 'curr_resync'
equals 'max_sectors'.

Link: https://lore.kernel.org/linux-raid/20260105110300.1442509-9-linan666@huaweicloud.com
Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Yu Kuai <yukuai@fnnas.com>
Signed-off-by: Yu Kuai <yukuai@fnnas.com>

1 files changed, 47 insertions, 35 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 3ef845af552b..7b4fe7379bb6 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -9438,6 +9438,51 @@ static bool sync_io_within_limit(struct mddev *mddev)
 	       (raid_is_456(mddev) ? 8 : 128) * sync_io_depth(mddev);
 }
 
+/*
+ * Update sync offset and mddev status when sync completes
+ */
+static void md_finish_sync(struct mddev *mddev, enum sync_action action)
+{
+	struct md_rdev *rdev;
+
+	switch (action) {
+	case ACTION_RESYNC:
+	case ACTION_REPAIR:
+		if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+			mddev->curr_resync = MaxSector;
+		mddev->resync_offset = mddev->curr_resync;
+		break;
+	case ACTION_RECOVER:
+		if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+			mddev->curr_resync = MaxSector;
+		rcu_read_lock();
+		rdev_for_each_rcu(rdev, mddev)
+			if (mddev->delta_disks >= 0 &&
+			    rdev_needs_recovery(rdev, mddev->curr_resync))
+				rdev->recovery_offset = mddev->curr_resync;
+		rcu_read_unlock();
+		break;
+	case ACTION_RESHAPE:
+		if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
+		    mddev->delta_disks > 0 &&
+		    mddev->pers->finish_reshape &&
+		    mddev->pers->size &&
+		    !mddev_is_dm(mddev)) {
+			mddev_lock_nointr(mddev);
+			md_set_array_sectors(mddev, mddev->pers->size(mddev, 0, 0));
+			mddev_unlock(mddev);
+			if (!mddev_is_clustered(mddev))
+				set_capacity_and_notify(mddev->gendisk,
+							mddev->array_sectors);
+		}
+		break;
+	/* */
+	case ACTION_CHECK:
+	default:
+		break;
+	}
+}
+
 #define SYNC_MARKS	10
 #define	SYNC_MARK_STEP	(3*HZ)
 #define UPDATE_FREQUENCY (5*60*HZ)
@@ -9453,7 +9498,6 @@ void md_do_sync(struct md_thread *thread)
 	int last_mark,m;
 	sector_t last_check;
 	int skipped = 0;
-	struct md_rdev *rdev;
 	enum sync_action action;
 	const char *desc;
 	struct blk_plug plug;
@@ -9746,46 +9790,14 @@ update:
 	}
 	mddev->pers->sync_request(mddev, max_sectors, max_sectors, &skipped);
 
-	if (!test_bit(MD_RECOVERY_CHECK, &mddev->recovery) &&
-	    mddev->curr_resync > MD_RESYNC_ACTIVE) {
-		if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery))
-			mddev->curr_resync = MaxSector;
-
-		if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
-			mddev->resync_offset = mddev->curr_resync;
-		} else {
-			if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
-			    test_bit(MD_RECOVERY_RECOVER, &mddev->recovery)) {
-				rcu_read_lock();
-				rdev_for_each_rcu(rdev, mddev)
-					if (mddev->delta_disks >= 0 &&
-					    rdev_needs_recovery(rdev, mddev->curr_resync))
-						rdev->recovery_offset = mddev->curr_resync;
-				rcu_read_unlock();
-			}
-		}
-	}
+	if (mddev->curr_resync > MD_RESYNC_ACTIVE)
+		md_finish_sync(mddev, action);
  skip:
 	/* set CHANGE_PENDING here since maybe another update is needed,
 	 * so other nodes are informed. It should be harmless for normal
 	 * raid */
 	set_mask_bits(&mddev->sb_flags, 0,
 		      BIT(MD_SB_CHANGE_PENDING) | BIT(MD_SB_CHANGE_DEVS));
-
-	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
-			!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
-			mddev->delta_disks > 0 &&
-			mddev->pers->finish_reshape &&
-			mddev->pers->size &&
-			!mddev_is_dm(mddev)) {
-		mddev_lock_nointr(mddev);
-		md_set_array_sectors(mddev, mddev->pers->size(mddev, 0, 0));
-		mddev_unlock(mddev);
-		if (!mddev_is_clustered(mddev))
-			set_capacity_and_notify(mddev->gendisk,
-						mddev->array_sectors);
-	}
-
 	spin_lock(&mddev->lock);
 	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
 		/* We completed so min/max setting can be forgotten if used. */