md/md-bitmap: merge md_bitmap_wait_behind_writes() into bitmap_operations

So that the implementation won't be exposed, and it'll be possible
to invent a new bitmap by replacing bitmap_operations.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240826074452.1490072-41-yukuai1@huaweicloud.comSigned-off-by: Song Liu <song@kernel.org>

drivers/md/md-bitmap.c

@@ -1863,7 +1863,7 @@ static void md_bitmap_free(struct bitmap *bitmap)
 	kfree(bitmap);
 }
 
-void md_bitmap_wait_behind_writes(struct mddev *mddev)
+static void bitmap_wait_behind_writes(struct mddev *mddev)
 {
 	struct bitmap *bitmap = mddev->bitmap;
 
@@ -1876,7 +1876,6 @@ void md_bitmap_wait_behind_writes(struct mddev *mddev)
 			   atomic_read(&bitmap->behind_writes) == 0);
 	}
 }
-EXPORT_SYMBOL_GPL(md_bitmap_wait_behind_writes);
 
 static void bitmap_destroy(struct mddev *mddev)
 {
@@ -1885,7 +1884,7 @@ static void bitmap_destroy(struct mddev *mddev)
 	if (!bitmap) /* there was no bitmap */
 		return;
 
-	md_bitmap_wait_behind_writes(mddev);
+	bitmap_wait_behind_writes(mddev);
 	if (!mddev->serialize_policy)
 		mddev_destroy_serial_pool(mddev, NULL);
 
@@ -2763,6 +2762,7 @@ static struct bitmap_operations bitmap_ops = {
 	.dirty_bits		= bitmap_dirty_bits,
 	.unplug			= bitmap_unplug,
 	.daemon_work		= bitmap_daemon_work,
+	.wait_behind_writes	= bitmap_wait_behind_writes,
 
 	.startwrite		= bitmap_startwrite,
 	.endwrite		= bitmap_endwrite,

drivers/md/md-bitmap.h

@@ -259,6 +259,7 @@ struct bitmap_operations {
 			   unsigned long e);
 	void (*unplug)(struct mddev *mddev, bool sync);
 	void (*daemon_work)(struct mddev *mddev);
+	void (*wait_behind_writes)(struct mddev *mddev);
 
 	int (*startwrite)(struct mddev *mddev, sector_t offset,
 			  unsigned long sectors, bool behind);
@@ -286,9 +287,6 @@ struct bitmap_operations {
 /* the bitmap API */
 void mddev_set_bitmap_ops(struct mddev *mddev);
 
-/* these are exported */
-void md_bitmap_wait_behind_writes(struct mddev *mddev);
-
 static inline bool md_bitmap_enabled(struct bitmap *bitmap)
 {
 	return bitmap && bitmap->storage.filemap &&

drivers/md/md.c

@@ -6498,7 +6498,7 @@ EXPORT_SYMBOL_GPL(md_stop_writes);
 
 static void mddev_detach(struct mddev *mddev)
 {
-	md_bitmap_wait_behind_writes(mddev);
+	mddev->bitmap_ops->wait_behind_writes(mddev);
 	if (mddev->pers && mddev->pers->quiesce && !is_md_suspended(mddev)) {
 		mddev->pers->quiesce(mddev, 1);
 		mddev->pers->quiesce(mddev, 0);

drivers/md/raid1.c

@@ -1371,7 +1371,7 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio,
 		 * over-take any writes that are 'behind'
 		 */
 		mddev_add_trace_msg(mddev, "raid1 wait behind writes");
-		md_bitmap_wait_behind_writes(mddev);
+		mddev->bitmap_ops->wait_behind_writes(mddev);
 	}
 
 	if (max_sectors < bio_sectors(bio)) {