> + if (test_and_set_bit(BD_FREEZE_OP, &bdev->bd_state)) > + return ERR_PTR(-EBUSY); > + > + sb = get_super_without_lock(bdev); > + > + /* If super_block has been already frozen, return. */ > + if (sb && sb->s_frozen != SB_UNFROZEN) { > + put_super(sb); > + clear_bit(BD_FREEZE_OP, &bdev->bd_state); > + return sb; > + } The BD_FREEZE_OP flag in the block_device already prevents multiple freezes for a singe block device, so there is no need for this additional check and the get_super_without_lock helper. > down(&bdev->bd_mount_sem); And with that flag bd_mount_sem is also obsolete for preventing the multiple freeze operations. We still need investigate what synchronization we need vs unmount which also takes bd_mount_sem without every having document what it exactly protects. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel