Commit aae4eea6 authored by Kent Overstreet's avatar Kent Overstreet Committed by Kent Overstreet
Browse files

bcachefs: Improve btree_node_mem_ptr optimization 



This patch checks b->hash_val before attempting to lock the node in the
btree, which makes it more equivalent to the "lookup in hash table"
path - and potentially avoids an unnecessary transaction restart if
btree_node_mem_ptr(k) no longer points to the node we want.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@gmail.com>
parent aa76bd33

fs/bcachefs/btree_cache.c

+6 −1
Original line number Diff line number Diff line
@@ -777,7 +777,12 @@ struct btree *bch2_btree_node_get(struct btree_trans *trans, struct btree_path * 


	if (c->opts.btree_node_mem_ptr_optimization) {

		b = btree_node_mem_ptr(k);

		if (b)

		/*

		 * Check b->hash_val _before_ calling btree_node_lock() - this

		 * might not be the node we want anymore, and trying to lock the

		 * wrong node could cause an unneccessary transaction restart:

		 */

		if (b && b->hash_val == btree_ptr_hash_val(k))

			goto lock_node;

	}

retry: