+ if (unlikely(btree_node_read_error(b))) {
+ six_unlock_type(&b->c.lock, lock_type);
+ return ERR_PTR(-EIO);
+ }
+
+ EBUG_ON(b->c.btree_id != path->btree_id);
+ EBUG_ON(BTREE_NODE_LEVEL(b->data) != level);
+ btree_check_header(c, b);
+
+ return b;
+}
+
+/**
+ * bch_btree_node_get - find a btree node in the cache and lock it, reading it
+ * in from disk if necessary.
+ *
+ * If IO is necessary and running under generic_make_request, returns -EAGAIN.
+ *
+ * The btree node will have either a read or a write lock held, depending on
+ * the @write parameter.
+ */
+struct btree *bch2_btree_node_get(struct btree_trans *trans, struct btree_path *path,
+ const struct bkey_i *k, unsigned level,
+ enum six_lock_type lock_type,
+ unsigned long trace_ip)
+{
+ struct bch_fs *c = trans->c;
+ struct btree *b;
+ struct bset_tree *t;
+ int ret;
+
+ EBUG_ON(level >= BTREE_MAX_DEPTH);
+
+ b = btree_node_mem_ptr(k);
+
+ /*
+ * 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 (unlikely(!c->opts.btree_node_mem_ptr_optimization ||
+ !b ||
+ b->hash_val != btree_ptr_hash_val(k)))
+ return __bch2_btree_node_get(trans, path, k, level, lock_type, trace_ip);
+
+ if (btree_node_read_locked(path, level + 1))
+ btree_node_unlock(trans, path, level + 1);
+
+ ret = btree_node_lock(trans, path, &b->c, level, lock_type, trace_ip);
+ if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
+ return ERR_PTR(ret);
+
+ BUG_ON(ret);
+
+ if (unlikely(b->hash_val != btree_ptr_hash_val(k) ||
+ b->c.level != level ||
+ race_fault())) {
+ six_unlock_type(&b->c.lock, lock_type);
+ if (bch2_btree_node_relock(trans, path, level + 1))
+ return __bch2_btree_node_get(trans, path, k, level, lock_type, trace_ip);
+
+ trace_and_count(c, trans_restart_btree_node_reused, trans, trace_ip, path);
+ return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_lock_node_reused));
+ }
+
+ if (unlikely(btree_node_read_in_flight(b))) {
+ u32 seq = b->c.lock.state.seq;
+
+ six_unlock_type(&b->c.lock, lock_type);
+ bch2_trans_unlock(trans);
+
+ bch2_btree_node_wait_on_read(b);
+
+ /*
+ * should_be_locked is not set on this path yet, so we need to
+ * relock it specifically:
+ */
+ if (trans) {
+ int ret = bch2_trans_relock(trans) ?:
+ bch2_btree_path_relock_intent(trans, path);
+ if (ret) {
+ BUG_ON(!trans->restarted);
+ return ERR_PTR(ret);
+ }
+ }
+
+ if (!six_relock_type(&b->c.lock, lock_type, seq))
+ return __bch2_btree_node_get(trans, path, k, level, lock_type, trace_ip);
+ }
+
+ prefetch(b->aux_data);
+
+ for_each_bset(b, t) {
+ void *p = (u64 *) b->aux_data + t->aux_data_offset;
+
+ prefetch(p + L1_CACHE_BYTES * 0);
+ prefetch(p + L1_CACHE_BYTES * 1);
+ prefetch(p + L1_CACHE_BYTES * 2);
+ }
+