if (IS_ERR(b))
return b;
+ /*
+ * Btree nodes read in from disk should not have the accessed bit set
+ * initially, so that linear scans don't thrash the cache:
+ */
+ clear_btree_node_accessed(b);
+
bkey_copy(&b->key, k);
if (bch2_btree_node_hash_insert(bc, b, level, btree_id)) {
/* raced with another fill: */
{
if (b->c.btree_id != BTREE_NODE_ID(b->data) ||
b->c.level != BTREE_NODE_LEVEL(b->data) ||
- bpos_cmp(b->data->max_key, b->key.k.p) ||
+ !bpos_eq(b->data->max_key, b->key.k.p) ||
(b->key.k.type == KEY_TYPE_btree_ptr_v2 &&
- bpos_cmp(b->data->min_key,
+ !bpos_eq(b->data->min_key,
bkey_i_to_btree_ptr_v2(&b->key)->v.min_key)))
btree_bad_header(c, 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)
+static 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_cache *bc = &c->btree_cache;
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 (likely(c->opts.btree_node_mem_ptr_optimization &&
- b &&
- b->hash_val == btree_ptr_hash_val(k)))
- goto lock_node;
retry:
b = btree_cache_find(bc, k);
if (unlikely(!b)) {
if (IS_ERR(b))
return b;
} else {
-lock_node:
- /*
- * There's a potential deadlock with splits and insertions into
- * interior nodes we have to avoid:
- *
- * The other thread might be holding an intent lock on the node
- * we want, and they want to update its parent node so they're
- * going to upgrade their intent lock on the parent node to a
- * write lock.
- *
- * But if we're holding a read lock on the parent, and we're
- * trying to get the intent lock they're holding, we deadlock.
- *
- * So to avoid this we drop the read locks on parent nodes when
- * we're starting to take intent locks - and handle the race.
- *
- * The race is that they might be about to free the node we
- * want, and dropping our read lock on the parent node lets them
- * update the parent marking the node we want as freed, and then
- * free it:
- *
- * To guard against this, btree nodes are evicted from the cache
- * when they're freed - and b->hash_val is zeroed out, which we
- * check for after we lock the node.
- *
- * Then, bch2_btree_node_relock() on the parent will fail - because
- * the parent was modified, when the pointer to the node we want
- * was removed - and we'll bail out:
- */
if (btree_node_read_locked(path, level + 1))
btree_node_unlock(trans, path, level + 1);
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));
}
+
+ /* avoid atomic set bit if it's not needed: */
+ if (!btree_node_accessed(b))
+ set_btree_node_accessed(b);
}
if (unlikely(btree_node_read_in_flight(b))) {
prefetch(p + L1_CACHE_BYTES * 2);
}
+ 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);
+ }
+
/* avoid atomic set bit if it's not needed: */
if (!btree_node_accessed(b))
set_btree_node_accessed(b);
projects / bcachefs-tools-debian / blobdiff