On Mon, Aug 6, 2012 at 3:18 PM, Arne Jansen <[email protected]> wrote: > Commit a168650c introduced a waiting mechanism to prevent busy waiting in > btrfs_run_delayed_refs. This can deadlock with btrfs_run_ordered_operations, > where a tree_mod_seq is held while waiting for the io to complete, while > the end_io calls btrfs_run_delayed_refs. > This whole mechanism is unnecessary. If not enough runnable refs are > available to satisfy count, just return as count is more like a guideline > than a strict requirement. > In case we have to run all refs, commit transaction makes sure that no > other threads are working in the transaction anymore, so we just assert > here that no refs are blocked. >
I've been testing this patch after manually merging on top of Josef's "Btrfs: barrier before waitqueue_active V2" patch. With that arrangement, I've been unable to reproduce the deadlock on my system. I'll continue banging away on it tomorrow, and let you know if I attain a deadlock. Also, let me know if you need me to test without including Josef's added barriers. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
