diff --git a/fs/bcachefs/btree_key_cache.c b/fs/bcachefs/btree_key_cache.c index 9b3ec2a3b8ce..fda7998734cb 100644 --- a/fs/bcachefs/btree_key_cache.c +++ b/fs/bcachefs/btree_key_cache.c @@ -778,6 +778,20 @@ static unsigned long bch2_btree_key_cache_scan(struct shrinker *shrink, rcu_read_lock(); tbl = rht_dereference_rcu(bc->table.tbl, &bc->table); + + /* + * Scanning is expensive while a rehash is in progress - most elements + * will be on the new hashtable, if it's in progress + * + * A rehash could still start while we're scanning - that's ok, we'll + * still see most elements. + */ + if (unlikely(tbl->nest)) { + rcu_read_unlock(); + srcu_read_unlock(&c->btree_trans_barrier, srcu_idx); + return SHRINK_STOP; + } + if (bc->shrink_iter >= tbl->size) bc->shrink_iter = 0; start = bc->shrink_iter; @@ -785,7 +799,7 @@ static unsigned long bch2_btree_key_cache_scan(struct shrinker *shrink, do { struct rhash_head *pos, *next; - pos = rht_ptr_rcu(rht_bucket(tbl, bc->shrink_iter)); + pos = rht_ptr_rcu(&tbl->buckets[bc->shrink_iter]); while (!rht_is_a_nulls(pos)) { next = rht_dereference_bucket_rcu(pos->next, tbl, bc->shrink_iter); @@ -866,12 +880,22 @@ void bch2_fs_btree_key_cache_exit(struct btree_key_cache *bc) while (atomic_long_read(&bc->nr_keys)) { rcu_read_lock(); tbl = rht_dereference_rcu(bc->table.tbl, &bc->table); - if (tbl) + if (tbl) { + if (tbl->nest) { + /* wait for in progress rehash */ + rcu_read_unlock(); + mutex_lock(&bc->table.mutex); + mutex_unlock(&bc->table.mutex); + rcu_read_lock(); + continue; + } for (i = 0; i < tbl->size; i++) - rht_for_each_entry_rcu(ck, pos, tbl, i, hash) { + while (pos = rht_ptr_rcu(&tbl->buckets[i]), !rht_is_a_nulls(pos)) { + ck = container_of(pos, struct bkey_cached, hash); bkey_cached_evict(bc, ck); list_add(&ck->list, &items); } + } rcu_read_unlock(); }