On Thu, Dec 02, 2021 at 07:05:00PM +0100, Jan Kara wrote: > So the advantage of using task work instead of just dropping open_mutex > before calling __loop_clr_fd() is that if something in block/bdev.c ever > changes and starts relying on open_mutex being held throughout blkdev_put() > then loop device handling will not suddently become broken. Generally it is > a bad practice to drop locks (even temporarily) upper layers have acquired. > Sometimes it is inevitable in in this case we can avoid that... So I'd > prefer if we used task work instead of dropping open_mutex inside loop > driver. Not sure what's Christoph's opinion though, I don't feel *that* > strongly about it. Dropping the lock is a complete no go a it doesn't allow proper reasoning about the locking scheme in the block layer. task_work_add sounds nice, but it is currently not exported which might be for a reason (I don't really have any experience with it).
