md: Convert to bdev_open_by_dev()

Convert md to use bdev_open_by_dev() and pass the handle around. We also
don't need the 'Holder' flag anymore so remove it.

CC: linux-raid@vger.kernel.org
CC: Song Liu <song@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230927093442.25915-11-jack@suse.czSigned-off-by: Christian Brauner <brauner@kernel.org>

drivers/md/md.c

@@ -2452,8 +2452,7 @@ static void export_rdev(struct md_rdev *rdev, struct mddev *mddev)
 	if (test_bit(AutoDetected, &rdev->flags))
 		md_autodetect_dev(rdev->bdev->bd_dev);
 #endif
-	blkdev_put(rdev->bdev,
-		   test_bit(Holder, &rdev->flags) ? rdev : &claim_rdev);
+	bdev_release(rdev->bdev_handle);
 	rdev->bdev = NULL;
 	kobject_put(&rdev->kobj);
 }
@@ -3633,7 +3632,6 @@ EXPORT_SYMBOL_GPL(md_rdev_init);
 static struct md_rdev *md_import_device(dev_t newdev, int super_format, int super_minor)
 {
 	struct md_rdev *rdev;
-	struct md_rdev *holder;
 	sector_t size;
 	int err;
 
@@ -3648,21 +3646,16 @@ static struct md_rdev *md_import_device(dev_t newdev, int super_format, int supe
 	if (err)
 		goto out_clear_rdev;
 
-	if (super_format == -2) {
-		holder = &claim_rdev;
-	} else {
-		holder = rdev;
-		set_bit(Holder, &rdev->flags);
-	}
-
-	rdev->bdev = blkdev_get_by_dev(newdev, BLK_OPEN_READ | BLK_OPEN_WRITE,
-				       holder, NULL);
-	if (IS_ERR(rdev->bdev)) {
+	rdev->bdev_handle = bdev_open_by_dev(newdev,
+			BLK_OPEN_READ | BLK_OPEN_WRITE,
+			super_format == -2 ? &claim_rdev : rdev, NULL);
+	if (IS_ERR(rdev->bdev_handle)) {
 		pr_warn("md: could not open device unknown-block(%u,%u).\n",
 			MAJOR(newdev), MINOR(newdev));
-		err = PTR_ERR(rdev->bdev);
+		err = PTR_ERR(rdev->bdev_handle);
 		goto out_clear_rdev;
 	}
+	rdev->bdev = rdev->bdev_handle->bdev;
 
 	kobject_init(&rdev->kobj, &rdev_ktype);
 
@@ -3693,7 +3686,7 @@ static struct md_rdev *md_import_device(dev_t newdev, int super_format, int supe
 	return rdev;
 
 out_blkdev_put:
-	blkdev_put(rdev->bdev, holder);
+	bdev_release(rdev->bdev_handle);
 out_clear_rdev:
 	md_rdev_clear(rdev);
 out_free_rdev:

drivers/md/md.h

@@ -59,6 +59,7 @@ struct md_rdev {
 	 */
 	struct block_device *meta_bdev;
 	struct block_device *bdev;	/* block device handle */
+	struct bdev_handle *bdev_handle;	/* Handle from open for bdev */
 
 	struct page	*sb_page, *bb_page;
 	int		sb_loaded;
@@ -211,9 +212,6 @@ enum flag_bits {
 				 * check if there is collision between raid1
 				 * serial bios.
 				 */
-	Holder,			/* rdev is used as holder while opening
-				 * underlying disk exclusively.
-				 */
 };
 
 static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors,