Hi, 在 2025/05/12 13:17, Christoph Hellwig 写道:
On Mon, May 12, 2025 at 09:19:23AM +0800, Yu Kuai wrote:+static void llbitmap_unplug(struct mddev *mddev, bool sync) +{ + DECLARE_COMPLETION_ONSTACK(done); + struct llbitmap *llbitmap = mddev->bitmap; + struct llbitmap_unplug_work unplug_work = { + .llbitmap = llbitmap, + .done = &done, + }; + + if (!llbitmap_dirty(llbitmap)) + return; + + 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? Thanks, Kuai
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