md/md-bitmap: add 'sync_size' into struct md_bitmap_stats

To avoid dereferencing bitmap directly in md-cluster to prepare
inventing a new bitmap.

BTW, also fix following checkpatch warnings:

WARNING: Deprecated use of 'kmap_atomic', prefer 'kmap_local_page' instead
WARNING: Deprecated use of 'kunmap_atomic', prefer 'kunmap_local' instead

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240826074452.1490072-7-yukuai1@huaweicloud.com
Signed-off-by: Song Liu <song@kernel.org>

drivers/md/md-bitmap.c

@@ -2097,10 +2097,15 @@ EXPORT_SYMBOL_GPL(md_bitmap_copy_from_slot);
 int md_bitmap_get_stats(struct bitmap *bitmap, struct md_bitmap_stats *stats)
 {
 	struct bitmap_counts *counts;
+	bitmap_super_t *sb;
 
 	if (!bitmap)
 		return -ENOENT;
 
+	sb = kmap_local_page(bitmap->storage.sb_page);
+	stats->sync_size = le64_to_cpu(sb->sync_size);
+	kunmap_local(sb);
+
 	counts = &bitmap->counts;
 	stats->missing_pages = counts->missing_pages;
 	stats->pages = counts->pages;
@@ -2110,6 +2115,7 @@ int md_bitmap_get_stats(struct bitmap *bitmap, struct md_bitmap_stats *stats)
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(md_bitmap_get_stats);
 
 int md_bitmap_resize(struct bitmap *bitmap, sector_t blocks,
 		  int chunksize, int init)

drivers/md/md-bitmap.h

@@ -237,6 +237,7 @@ struct bitmap {
 struct md_bitmap_stats {
 	u64		events_cleared;
 	unsigned long	missing_pages;
+	unsigned long	sync_size;
 	unsigned long	pages;
 	struct file	*file;
 };

drivers/md/md-cluster.c

@@ -1207,18 +1207,21 @@ static int resize_bitmaps(struct mddev *mddev, sector_t newsize, sector_t oldsiz
  */
 static int cluster_check_sync_size(struct mddev *mddev)
 {
-	int i, rv;
-	bitmap_super_t *sb;
-	unsigned long my_sync_size, sync_size = 0;
-	int node_num = mddev->bitmap_info.nodes;
 	int current_slot = md_cluster_ops->slot_number(mddev);
+	int node_num = mddev->bitmap_info.nodes;
 	struct bitmap *bitmap = mddev->bitmap;
-	char str[64];
 	struct dlm_lock_resource *bm_lockres;
+	struct md_bitmap_stats stats;
+	unsigned long sync_size = 0;
+	unsigned long my_sync_size;
+	char str[64];
+	int i, rv;
 
-	sb = kmap_atomic(bitmap->storage.sb_page);
-	my_sync_size = le64_to_cpu(sb->sync_size);
-	kunmap_atomic(sb);
+	rv = md_bitmap_get_stats(bitmap, &stats);
+	if (rv)
+		return rv;
+
+	my_sync_size = stats.sync_size;
 
 	for (i = 0; i < node_num; i++) {
 		if (i == current_slot)
@@ -1247,15 +1250,18 @@ static int cluster_check_sync_size(struct mddev *mddev)
 			md_bitmap_update_sb(bitmap);
 		lockres_free(bm_lockres);
 
-		sb = kmap_atomic(bitmap->storage.sb_page);
-		if (sync_size == 0)
-			sync_size = le64_to_cpu(sb->sync_size);
-		else if (sync_size != le64_to_cpu(sb->sync_size)) {
-			kunmap_atomic(sb);
+		rv = md_bitmap_get_stats(bitmap, &stats);
+		if (rv) {
+			md_bitmap_free(bitmap);
+			return rv;
+		}
+
+		if (sync_size == 0) {
+			sync_size = stats.sync_size;
+		} else if (sync_size != stats.sync_size) {
 			md_bitmap_free(bitmap);
 			return -1;
 		}
-		kunmap_atomic(sb);
 		md_bitmap_free(bitmap);
 	}