From f5a7a6b0d9b6af7d46124ed3f6b3995225cb62d0 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 28 Jan 2008 23:58:27 -0500 Subject: jbd2: Fix assertion failure in fs/jbd2/checkpoint.c Before we start committing a transaction, we call __journal_clean_checkpoint_list() to cleanup transaction's written-back buffers. If this call happens to remove all of them (and there were already some buffers), __journal_remove_checkpoint() will decide to free the transaction because it isn't (yet) a committing transaction and soon we fail some assertion - the transaction really isn't ready to be freed :). We change the check in __journal_remove_checkpoint() to free only a transaction in T_FINISHED state. The locking there is subtle though (as everywhere in JBD ;(). We use j_list_lock to protect the check and a subsequent call to __journal_drop_transaction() and do the same in the end of journal_commit_transaction() which is the only place where a transaction can get to T_FINISHED state. Probably I'm too paranoid here and such locking is not really necessary - checkpoint lists are processed only from log_do_checkpoint() where a transaction must be already committed to be processed or from __journal_clean_checkpoint_list() where kjournald itself calls it and thus transaction cannot change state either. Better be safe if something changes in future... Signed-off-by: Jan Kara Cc: Signed-off-by: Andrew Morton --- include/linux/jbd2.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux') diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index d5f7cff4cb2..d861ffd4982 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -442,6 +442,8 @@ struct transaction_s /* * Transaction's current state * [no locking - only kjournald2 alters this] + * [j_list_lock] guards transition of a transaction into T_FINISHED + * state and subsequent call of __jbd2_journal_drop_transaction() * FIXME: needs barriers * KLUDGE: [use j_state_lock] */ -- cgit v1.2.3