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| author | Jan Kara <jack@suse.cz> | 2008-01-28 23:58:27 -0500 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2008-01-28 23:58:27 -0500 |
| commit | f5a7a6b0d9b6af7d46124ed3f6b3995225cb62d0 (patch) | |
| tree | cbb2bc79a488461bf3bec9b60d15e21717dc8360 /include/linux | |
| parent | 36df53f4a3e445175fc1e9d7f433599482ec6d7f (diff) | |
| download | lwn-f5a7a6b0d9b6af7d46124ed3f6b3995225cb62d0.tar.gz lwn-f5a7a6b0d9b6af7d46124ed3f6b3995225cb62d0.zip | |
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 <jack@suse.cz>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/jbd2.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index d5f7cff4cb28..d861ffd49821 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] */ |