bcachefs: btree_path

This splits btree_iter into two components: btree_iter is now the
externally visible componont, and it points to a btree_path which is now
reference counted.

This means we no longer have to clone iterators up front if they might
be mutated - btree_path can be shared by multiple iterators, and cloned
if an iterator would mutate a shared btree_path. This will help us use
iterators more efficiently, as well as slimming down the main long lived
state in btree_trans, and significantly cleans up the logic for iterator
lifetimes.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 3 insertions, 4 deletions

diff --git a/fs/bcachefs/btree_cache.h b/fs/bcachefs/btree_cache.h
index 3b671cf0056d..2f6e0ea87616 100644
--- a/fs/bcachefs/btree_cache.h
+++ b/fs/bcachefs/btree_cache.h
@@ -20,16 +20,15 @@ int bch2_btree_cache_cannibalize_lock(struct bch_fs *, struct closure *);
 struct btree *__bch2_btree_node_mem_alloc(struct bch_fs *);
 struct btree *bch2_btree_node_mem_alloc(struct bch_fs *);
 
-struct btree *bch2_btree_node_get(struct btree_trans *, struct btree_iter *,
+struct btree *bch2_btree_node_get(struct btree_trans *, struct btree_path *,
 				  const struct bkey_i *, unsigned,
 				  enum six_lock_type, unsigned long);
 
 struct btree *bch2_btree_node_get_noiter(struct bch_fs *, const struct bkey_i *,
 					 enum btree_id, unsigned, bool);
 
-int bch2_btree_node_prefetch(struct bch_fs *, struct btree_trans *,
-			     struct btree_iter *, const struct bkey_i *,
-			     enum btree_id, unsigned);
+int bch2_btree_node_prefetch(struct bch_fs *, struct btree_trans *, struct btree_path *,
+			     const struct bkey_i *, enum btree_id, unsigned);
 
 void bch2_btree_node_evict(struct bch_fs *, const struct bkey_i *);