With more machines running my recent delayed ref rsv patches we started seeing a spike in boxes aborting in __btrfs_free_extent with being unable to find the extent ref. The full details are in 2/2, but the summary is there's been a bug ever since the original delayed inode item stuff was introduced where it could run once the snapshot was being deleted, which will result in all sorts of extent reference shenanigans. This was tricky to hit before, but with my iput changes it's become much easier to hit on our build boxes that are heavy users of snapshot creation/deletion. Thanks, Josef
