@@ -1247,6 +1247,23 @@ struct btrfs_ordered_extent *btrfs_split_ordered_extent(
/* One ref for the tree. */
refcount_inc(&new->refs);
+ /*
+ * Take the root's ordered_extent_lock to avoid a race with
+ * btrfs_wait_ordered_extents() when updating the disk_bytenr and
+ * disk_num_bytes fields of the ordered extent below. And we disable
+ * IRQs because the inode's ordered_tree_lock is used in IRQ context
+ * elsewhere.
+ *
+ * There's no concern about a previous caller of
+ * btrfs_wait_ordered_extents() getting the trimmed ordered extent
+ * before we insert the new one, because even if it gets the ordered
+ * extent before it's trimmed and the new one inserted, right before it
+ * uses it or during its use, the ordered extent might have been
+ * trimmed in the meanwhile, and it missed the new ordered extent.
+ * There's no way around this and it's harmless for current use cases,
+ * so we take the root's ordered_extent_lock to fix that race during
+ * trimming and silence tools like KCSAN.
+ */
spin_lock_irq(&root->ordered_extent_lock);
spin_lock(&inode->ordered_tree_lock);
/* Remove from tree once */