ext4: wire up the ->mark_dead holder operation for log devices

Implement a set of holder_ops that shut down the file system when the
block device used as log device is removed undeneath the file system.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20230601094459.1350643-17-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

fs/ext4/super.c

@@ -1096,6 +1096,15 @@ void ext4_update_dynamic_rev(struct super_block *sb)
 	 */
 }
 
+static void ext4_bdev_mark_dead(struct block_device *bdev)
+{
+	ext4_force_shutdown(bdev->bd_holder, EXT4_GOING_FLAGS_NOLOGFLUSH);
+}
+
+static const struct blk_holder_ops ext4_holder_ops = {
+	.mark_dead		= ext4_bdev_mark_dead,
+};
+
 /*
  * Open the external journal device
  */
@@ -1104,7 +1113,7 @@ static struct block_device *ext4_blkdev_get(dev_t dev, struct super_block *sb)
 	struct block_device *bdev;
 
 	bdev = blkdev_get_by_dev(dev, FMODE_READ|FMODE_WRITE|FMODE_EXCL, sb,
-				 NULL);
+				 &ext4_holder_ops);
 	if (IS_ERR(bdev))
 		goto fail;
 	return bdev;