bcachefs: fix the count of nr_freed_pcpu after changing bc->freed_nonpcpu list

When allocating bkey_cached from bc->freed_pcpu list, it missed
decreasing the count of nr_freed_pcpu which would cause the mismatch
between the value of nr_freed_pcpu and the list items. This problem
also exists in moving new bkey_cached to bc->freed_pcpu list.
If these happened, the bug info may appear in
bch2_fs_btree_key_cache_exit by the follow code:

   BUG_ON(list_count_nodes(&bc->freed_pcpu) != bc->nr_freed_pcpu);
   BUG_ON(list_count_nodes(&bc->freed_nonpcpu) != bc->nr_freed_nonpcpu);

Fixes: c65c13f0eac6 ("bcachefs: Run btree key cache shrinker less aggressively")
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/btree_key_cache.c b/fs/bcachefs/btree_key_cache.c
index 4ae7890f07c6e39f9acb1c3f8e85303a2b7369c2..88a3582a32757e34a28eb37143f9ff78a88a4085 100644 (file)
--- a/fs/bcachefs/btree_key_cache.c
+++ b/fs/bcachefs/btree_key_cache.c
@@ -169,6 +169,7 @@ static void bkey_cached_move_to_freelist(struct btree_key_cache *bc,
        } else {
                mutex_lock(&bc->lock);
                list_move_tail(&ck->list, &bc->freed_pcpu);
+               bc->nr_freed_pcpu++;
                mutex_unlock(&bc->lock);
        }
 }
@@ -245,6 +246,7 @@ bkey_cached_alloc(struct btree_trans *trans, struct btree_path *path,
                if (!list_empty(&bc->freed_pcpu)) {
                        ck = list_last_entry(&bc->freed_pcpu, struct bkey_cached, list);
                        list_del_init(&ck->list);
+                       bc->nr_freed_pcpu--;
                }
                mutex_unlock(&bc->lock);
        }