Update bcachefs sources to 9e7ae5219c bcachefs: Make write points more dynamic

[bcachefs-tools-debian] / libbcachefs / btree_types.h

diff --git a/libbcachefs/btree_types.h b/libbcachefs/btree_types.h
index c0c162054bc754b61c3d7db8f45f4986eef94048..8b4df034f9261aaa47f4fad43ad84af80ab06438 100644 (file)
--- a/libbcachefs/btree_types.h
+++ b/libbcachefs/btree_types.h
@@ -130,6 +130,42 @@ struct btree {
 #endif
 };
 
+struct btree_cache {
+       struct rhashtable       table;
+       bool                    table_init_done;
+       /*
+        * We never free a struct btree, except on shutdown - we just put it on
+        * the btree_cache_freed list and reuse it later. This simplifies the
+        * code, and it doesn't cost us much memory as the memory usage is
+        * dominated by buffers that hold the actual btree node data and those
+        * can be freed - and the number of struct btrees allocated is
+        * effectively bounded.
+        *
+        * btree_cache_freeable effectively is a small cache - we use it because
+        * high order page allocations can be rather expensive, and it's quite
+        * common to delete and allocate btree nodes in quick succession. It
+        * should never grow past ~2-3 nodes in practice.
+        */
+       struct mutex            lock;
+       struct list_head        live;
+       struct list_head        freeable;
+       struct list_head        freed;
+
+       /* Number of elements in live + freeable lists */
+       unsigned                used;
+       unsigned                reserve;
+       struct shrinker         shrink;
+
+       /*
+        * If we need to allocate memory for a new btree node and that
+        * allocation fails, we can cannibalize another node in the btree cache
+        * to satisfy the allocation - lock to guarantee only one thread does
+        * this at a time:
+        */
+       struct task_struct      *alloc_lock;
+       struct closure_waitlist alloc_wait;
+};
+
 #define BTREE_FLAG(flag)                                               \
 static inline bool btree_node_ ## flag(struct btree *b)                        \
 {      return test_bit(BTREE_NODE_ ## flag, &b->flags); }              \