From d4beaf4ab5f89496f2bcf67db62ad95d99bfeff6 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Tue, 4 Dec 2007 23:45:27 -0800 Subject: jbd: Fix assertion failure in fs/jbd/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 Signed-off-by: Linus Torvalds --- include/linux/jbd.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/jbd.h') diff --git a/include/linux/jbd.h b/include/linux/jbd.h index 16e7ed855a18..d9ecd13393b0 100644 --- a/include/linux/jbd.h +++ b/include/linux/jbd.h @@ -439,6 +439,8 @@ struct transaction_s /* * Transaction's current state * [no locking - only kjournald alters this] + * [j_list_lock] guards transition of a transaction into T_FINISHED + * state and subsequent call of __journal_drop_transaction() * FIXME: needs barriers * KLUDGE: [use j_state_lock] */ -- cgit v1.2.3-58-ga151