bcachefs: fix failure to relock in bch2_btree_node_mem_alloc()

We weren't always so strict about trans->locked state - but now we are,
and new assertions are shaking some bugs out.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 17 insertions, 0 deletions

diff --git a/fs/bcachefs/btree_cache.c b/fs/bcachefs/btree_cache.c
index cc778d7e769e..063725ecb2b3 100644
--- a/fs/bcachefs/btree_cache.c
+++ b/fs/bcachefs/btree_cache.c
@@ -159,6 +159,16 @@ struct btree *__bch2_btree_node_mem_alloc(struct bch_fs *c)
 	return b;
 }
 
+void bch2_btree_node_to_freelist(struct bch_fs *c, struct btree *b)
+{
+	mutex_lock(&c->btree_cache.lock);
+	list_move(&b->list, &c->btree_cache.freeable);
+	mutex_unlock(&c->btree_cache.lock);
+
+	six_unlock_write(&b->c.lock);
+	six_unlock_intent(&b->c.lock);
+}
+
 /* Btree in memory cache - hash table */
 
 void bch2_btree_node_hash_remove(struct btree_cache *bc, struct btree *b)
@@ -736,6 +746,13 @@ out:
 			       start_time);
 
 	memalloc_nofs_restore(flags);
+
+	int ret = bch2_trans_relock(trans);
+	if (unlikely(ret)) {
+		bch2_btree_node_to_freelist(c, b);
+		return ERR_PTR(ret);
+	}
+
 	return b;
 err:
 	mutex_lock(&bc->lock);