On Tue, Oct 09, 2018 at 02:36:45PM +0800, Qu Wenruo wrote: > Some qgroup trace events like btrfs_qgroup_release_data() and > btrfs_qgroup_free_delayed_ref() can still be triggered even qgroup is > not enabled. > > This is caused by the lack of qgroup status check before really calling > qgroup functions. > Thankfully related functions can handle quota disabled case well and just > do nothing for qgroup disabled case. > > This patch will do earlier check before triggering related trace events. > > And for enabled <-> disabled race case: > 1) For enabled->disabled case > Disable will wipe out all qgroups data including reservation and > excl/rfer. Even we leaks some reserveration or numbers, it will > still be wiped, so nothing can go wrong. > > 2) For disabled -> enabled case > Current btrfs_qgroup_release_data() will use extent_io tree to ensure > we won't underflow reservation. And for delayed_ref we use > head->qgroup_reserved to record reserved space, so in that case > head->qgroup_reserved should be 0 and we won't underflow. > > Reported-by: Chris Murphy <lists@xxxxxxxxxxxxxxxxx> > Signed-off-by: Qu Wenruo <wqu@xxxxxxxx> Reviewed-by: David Sterba <dsterba@xxxxxxxx> I've added the link to the report.
