fs/btrfs/discard.c

570  * discardable_extents.  Clamp this between the lower_limit (iops_limit or 1ms)
575 	s32 discardable_extents;
581 	discardable_extents = atomic_read(&discard_ctl->discardable_extents);
582 	if (!discardable_extents)
594 	if (discardable_extents < 0)
595 		atomic_add(-discardable_extents,
596 			   &discard_ctl->discardable_extents);
603 	if (discardable_extents <= 0) {
652 	extents_delta = ctl->discardable_extents[BTRFS_STAT_CURR] -
653 			ctl->discardable_extents[BTRFS_STAT_PREV];
655 		atomic_add(extents_delta, &discard_ctl->discardable_extents);
656 		ctl->discardable_extents[BTRFS_STAT_PREV] =
657 			ctl->discardable_extents[BTRFS_STAT_CURR];
761 	atomic_set(&discard_ctl->discardable_extents, 0);