From 35b814f3c53e0635cbb1de3ea5d58776eafe8e20 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov Date: Thu, 12 Sep 2019 18:31:44 +0300 Subject: [PATCH] btrfs: Add assert to catch nested transaction commit A recent patch to btrfs showed that there was at least 1 case where a nested transaction was committed. Nested transaction in this case means a code which has a transaction handle calls some function which in turn obtains a copy of the same transaction handle. In such cases the correct thing to do is for the lower callee to call btrfs_end_transaction which contains appropriate checks so as to not commit the transaction which will result in stale trans handler for the caller. To catch such cases add an assert in btrfs_commit_transaction ensuring btrfs_trans_handle::use_count is always 1. Reviewed-by: Josef Bacik Signed-off-by: Nikolay Borisov Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/transaction.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 8624bdee8c5b..8b75426c349e 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -1949,6 +1949,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) struct btrfs_transaction *prev_trans = NULL; int ret; + ASSERT(refcount_read(&trans->use_count) == 1); + /* Stop the commit early if ->aborted is set */ if (unlikely(READ_ONCE(cur_trans->aborted))) { ret = cur_trans->aborted;