diff options
author | Jan Kara <jack@suse.cz> | 2007-12-04 23:45:27 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-12-05 09:21:20 -0800 |
commit | d4beaf4ab5f89496f2bcf67db62ad95d99bfeff6 (patch) | |
tree | ae6d005199017e9a0ade169fd69cb73d6c0ac88f | |
parent | 369b8f5a70402d9fe77006cd0044c8a3fcd08430 (diff) | |
download | linux-d4beaf4ab5f89496f2bcf67db62ad95d99bfeff6.tar.bz2 |
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 <jack@suse.cz>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | fs/jbd/checkpoint.c | 12 | ||||
-rw-r--r-- | fs/jbd/commit.c | 8 | ||||
-rw-r--r-- | include/linux/jbd.h | 2 |
3 files changed, 12 insertions, 10 deletions
diff --git a/fs/jbd/checkpoint.c b/fs/jbd/checkpoint.c index 47552d4a6324..0f69c416eebc 100644 --- a/fs/jbd/checkpoint.c +++ b/fs/jbd/checkpoint.c @@ -602,15 +602,15 @@ int __journal_remove_checkpoint(struct journal_head *jh) /* * There is one special case to worry about: if we have just pulled the - * buffer off a committing transaction's forget list, then even if the - * checkpoint list is empty, the transaction obviously cannot be - * dropped! + * buffer off a running or committing transaction's checkpoing list, + * then even if the checkpoint list is empty, the transaction obviously + * cannot be dropped! * - * The locking here around j_committing_transaction is a bit sleazy. + * The locking here around t_state is a bit sleazy. * See the comment at the end of journal_commit_transaction(). */ - if (transaction == journal->j_committing_transaction) { - JBUFFER_TRACE(jh, "belongs to committing transaction"); + if (transaction->t_state != T_FINISHED) { + JBUFFER_TRACE(jh, "belongs to running/committing transaction"); goto out; } diff --git a/fs/jbd/commit.c b/fs/jbd/commit.c index 8f1f2aa5fb39..610264b99a8e 100644 --- a/fs/jbd/commit.c +++ b/fs/jbd/commit.c @@ -858,10 +858,10 @@ restart_loop: } spin_unlock(&journal->j_list_lock); /* - * This is a bit sleazy. We borrow j_list_lock to protect - * journal->j_committing_transaction in __journal_remove_checkpoint. - * Really, __journal_remove_checkpoint should be using j_state_lock but - * it's a bit hassle to hold that across __journal_remove_checkpoint + * This is a bit sleazy. We use j_list_lock to protect transition + * of a transaction into T_FINISHED state and calling + * __journal_drop_transaction(). Otherwise we could race with + * other checkpointing code processing the transaction... */ spin_lock(&journal->j_state_lock); spin_lock(&journal->j_list_lock); 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] */ |