md/md-cluster: use helper md_bitmap_get_stats() to get pages in resize_bitmaps()

Use the existed helper instead of open coding it, avoid dereferencing
bitmap directly to prepare inventing a new bitmap.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240826074452.1490072-10-yukuai1@huaweicloud.comSigned-off-by: Song Liu <song@kernel.org>

drivers/md/md-cluster.c

@@ -1143,13 +1143,16 @@ static int update_bitmap_size(struct mddev *mddev, sector_t size)
 
 static int resize_bitmaps(struct mddev *mddev, sector_t newsize, sector_t oldsize)
 {
-	struct bitmap_counts *counts;
-	char str[64];
-	struct dlm_lock_resource *bm_lockres;
 	struct bitmap *bitmap = mddev->bitmap;
-	unsigned long my_pages = bitmap->counts.pages;
+	struct md_bitmap_stats stats;
+	unsigned long my_pages;
 	int i, rv;
 
+	rv = md_bitmap_get_stats(bitmap, &stats);
+	if (rv)
+		return rv;
+
+	my_pages = stats.pages;
 	/*
 	 * We need to ensure all the nodes can grow to a larger
 	 * bitmap size before make the reshaping.
@@ -1159,6 +1162,10 @@ static int resize_bitmaps(struct mddev *mddev, sector_t newsize, sector_t oldsiz
 		return rv;
 
 	for (i = 0; i < mddev->bitmap_info.nodes; i++) {
+		struct dlm_lock_resource *bm_lockres;
+		struct bitmap_counts *counts;
+		char str[64];
+
 		if (i == md_cluster_ops->slot_number(mddev))
 			continue;
 
@@ -1170,6 +1177,9 @@ static int resize_bitmaps(struct mddev *mddev, sector_t newsize, sector_t oldsiz
 		}
 		counts = &bitmap->counts;
 
+		rv = md_bitmap_get_stats(bitmap, &stats);
+		if (rv)
+			goto out;
 		/*
 		 * If we can hold the bitmap lock of one node then
 		 * the slot is not occupied, update the pages.
@@ -1186,7 +1196,7 @@ static int resize_bitmaps(struct mddev *mddev, sector_t newsize, sector_t oldsiz
 			counts->pages = my_pages;
 		lockres_free(bm_lockres);
 
-		if (my_pages != counts->pages)
+		if (my_pages != stats.pages)
 			/*
 			 * Let's revert the bitmap size if one node
 			 * can't resize bitmap