On Mon, May 12, 2025 at 04:23:55PM +0800, Yu Kuai wrote: >>> + INIT_WORK_ONSTACK(&unplug_work.work, llbitmap_unplug_fn); >>> + queue_work(md_llbitmap_unplug_wq, &unplug_work.work); >>> + wait_for_completion(&done); >>> + destroy_work_on_stack(&unplug_work.work); >> >> Why is this deferring the work to a workqueue, but then synchronously >> waits on it? > > This is the same as old bitmap, by the fact that issue new IO and wait > for such IO to be done from submit_bio() context will deadlock. > > 1) bitmap bio must be done before this bio can be issued; > 2) bitmap bio will be added to current->bio_list, and wait for this bio > to be issued; > > Do you have a better sulution to this problem?
A bew block layer API that bypasses bio_list maybe? I.e. export __submit_bio with a better name and a kerneldoc detailing the narrow use case.
