bcachefs: fix the memory leak in exception case

The pointer clean points the memory allocated by kmemdup, when the
return value of bch2_sb_clean_validate_late is not zero. The memory
pointed by clean is leaked. So we should free it in this case.

Fixes: a37ad1a3 ("bcachefs: sb-clean.c")
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/sb-clean.c

@@ -167,6 +167,7 @@ struct bch_sb_field_clean *bch2_read_superblock_clean(struct bch_fs *c)
 
 	ret = bch2_sb_clean_validate_late(c, clean, READ);
 	if (ret) {
+		kfree(clean);
 		mutex_unlock(&c->sb_lock);
 		return ERR_PTR(ret);
 	}