vboxsf: don't use the source name in the bdi name

Simplify the bdi name to mirror what we are doing elsewhere, and
drop them name in favor of just using a number.  This avoids a
potentially very long bdi name.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/vboxsf/super.c

@@ -164,7 +164,7 @@ static int vboxsf_fill_super(struct super_block *sb, struct fs_context *fc)
 		goto fail_free;
 	}
 
-	err = super_setup_bdi_name(sb, "vboxsf-%s.%d", fc->source, sbi->bdi_id);
+	err = super_setup_bdi_name(sb, "vboxsf-%d", sbi->bdi_id);
 	if (err)
 		goto fail_free;