GitHub-Mirror/Star64_linux
2
0
Fork 0
mirror of https://github.com/Fishwaldo/Star64_linux.git synced 2025-06-29 10:01:25 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

jbd: Fix assertion failure in fs/jbd/checkpoint.c

Browse source 
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>
This commit is contained in:
Jan Kara 2007-12-04 23:45:27 -08:00 • committed by Linus Torvalds
parent 369b8f5a70
commit d4beaf4ab5
3 changed files with 12 additions and 10 deletions
Download patch file Download diff file Expand all files Collapse all files

8
fs/jbd/commit.c
View file

@ -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);