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-rw-r--r--fs/btrfs/locking.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/btrfs/locking.h b/fs/btrfs/locking.h
index 16563bc486c7..a6b59808e046 100644
--- a/fs/btrfs/locking.h
+++ b/fs/btrfs/locking.h
@@ -53,6 +53,15 @@ enum btrfs_lock_nesting {
BTRFS_NESTING_RIGHT_COW,
/*
+ * When splitting we may push nodes to the left or right, but still use
+ * the subsequent nodes in our path, keeping our locks on those adjacent
+ * blocks. Thus when we go to allocate a new split block we've already
+ * used up all of our available subclasses, so this subclass exists to
+ * handle this case where we need to allocate a new split block.
+ */
+ BTRFS_NESTING_SPLIT,
+
+ /*
* We are limited to MAX_LOCKDEP_SUBLCLASSES number of subclasses, so
* add this in here and add a static_assert to keep us from going over
* the limit. As of this writing we're limited to 8, and we're