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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: Kent Overstreet <kent.overstreet@gmail.com>
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1 changed files with 6 additions and 1 deletions
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@ -777,7 +777,12 @@ struct btree *bch2_btree_node_get(struct btree_trans *trans, struct btree_path *
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if (c->opts.btree_node_mem_ptr_optimization) {
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b = btree_node_mem_ptr(k);
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if (b)
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/*
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* Check b->hash_val _before_ calling btree_node_lock() - this
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* might not be the node we want anymore, and trying to lock the
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* wrong node could cause an unneccessary transaction restart:
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*/
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if (b && b->hash_val == btree_ptr_hash_val(k))
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goto lock_node;
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}
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retry:
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