md/md-bitmap: merge md_bitmap_startwrite() 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.

Also change the parameter from bitmap to mddev, to avoid access
bitmap outside md-bitmap.c as much as possible. And change the type
of 'behind' from int to bool.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240826074452.1490072-24-yukuai1@huaweicloud.comSigned-off-by: Song Liu <song@kernel.org>

drivers/md/md-bitmap.c

@@ -1458,8 +1458,11 @@ __acquires(bitmap->lock)
 			&(bitmap->bp[page].map[pageoff]);
 }
 
-int md_bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors, int behind)
+static int bitmap_startwrite(struct mddev *mddev, sector_t offset,
+			     unsigned long sectors, bool behind)
 {
+	struct bitmap *bitmap = mddev->bitmap;
+
 	if (!bitmap)
 		return 0;
 
@@ -1520,7 +1523,6 @@ int md_bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long s
 	}
 	return 0;
 }
-EXPORT_SYMBOL(md_bitmap_startwrite);
 
 void md_bitmap_endwrite(struct bitmap *bitmap, sector_t offset,
 			unsigned long sectors, int success, int behind)
@@ -2728,6 +2730,8 @@ static struct bitmap_operations bitmap_ops = {
 	.write_all		= bitmap_write_all,
 	.dirty_bits		= bitmap_dirty_bits,
 
+	.startwrite		= bitmap_startwrite,
+
 	.update_sb		= bitmap_update_sb,
 	.get_stats		= bitmap_get_stats,
 };

drivers/md/md-bitmap.h

@@ -255,6 +255,9 @@ struct bitmap_operations {
 	void (*dirty_bits)(struct mddev *mddev, unsigned long s,
 			   unsigned long e);
 
+	int (*startwrite)(struct mddev *mddev, sector_t offset,
+			  unsigned long sectors, bool behind);
+
 	void (*update_sb)(struct bitmap *bitmap);
 	int (*get_stats)(struct bitmap *bitmap, struct md_bitmap_stats *stats);
 };
@@ -263,8 +266,6 @@ struct bitmap_operations {
 void mddev_set_bitmap_ops(struct mddev *mddev);
 
 /* these are exported */
-int md_bitmap_startwrite(struct bitmap *bitmap, sector_t offset,
-			 unsigned long sectors, int behind);
 void md_bitmap_endwrite(struct bitmap *bitmap, sector_t offset,
 			unsigned long sectors, int success, int behind);
 int md_bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int degraded);

drivers/md/raid1.c

@@ -1604,7 +1604,8 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
 			    stats.behind_writes < max_write_behind)
 				alloc_behind_master_bio(r1_bio, bio);
 
-			md_bitmap_startwrite(bitmap, r1_bio->sector, r1_bio->sectors,
+			mddev->bitmap_ops->startwrite(
+				mddev, r1_bio->sector, r1_bio->sectors,
 				test_bit(R1BIO_BehindIO, &r1_bio->state));
 			first_clone = 0;
 		}

drivers/md/raid10.c

@@ -1492,7 +1492,8 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
 	md_account_bio(mddev, &bio);
 	r10_bio->master_bio = bio;
 	atomic_set(&r10_bio->remaining, 1);
-	md_bitmap_startwrite(mddev->bitmap, r10_bio->sector, r10_bio->sectors, 0);
+	mddev->bitmap_ops->startwrite(mddev, r10_bio->sector, r10_bio->sectors,
+				      false);
 
 	for (i = 0; i < conf->copies; i++) {
 		if (r10_bio->devs[i].bio)

drivers/md/raid5.c

@@ -3563,8 +3563,8 @@ static void __add_stripe_bio(struct stripe_head *sh, struct bio *bi,
 		 */
 		set_bit(STRIPE_BITMAP_PENDING, &sh->state);
 		spin_unlock_irq(&sh->stripe_lock);
-		md_bitmap_startwrite(conf->mddev->bitmap, sh->sector,
-				     RAID5_STRIPE_SECTORS(conf), 0);
+		conf->mddev->bitmap_ops->startwrite(conf->mddev, sh->sector,
+					RAID5_STRIPE_SECTORS(conf), false);
 		spin_lock_irq(&sh->stripe_lock);
 		clear_bit(STRIPE_BITMAP_PENDING, &sh->state);
 		if (!sh->batch_head) {
@@ -5788,13 +5788,10 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi)
 		}
 		spin_unlock_irq(&sh->stripe_lock);
 		if (conf->mddev->bitmap) {
-			for (d = 0;
-			     d < conf->raid_disks - conf->max_degraded;
+			for (d = 0; d < conf->raid_disks - conf->max_degraded;
 			     d++)
-				md_bitmap_startwrite(mddev->bitmap,
-						     sh->sector,
-						     RAID5_STRIPE_SECTORS(conf),
-						     0);
+				mddev->bitmap_ops->startwrite(mddev, sh->sector,
+					RAID5_STRIPE_SECTORS(conf), false);
 			sh->bm_seq = conf->seq_flush + 1;
 			set_bit(STRIPE_BIT_DELAY, &sh->state);
 		}