linux-ext4 - Re: [PATCH] jbd: fix assertion failure in journal_next_log

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-id: <20080131193543.GS23836@webber.adilger.int>
Date:	Thu, 31 Jan 2008 12:35:43 -0700
From:	Andreas Dilger <adilger@....com>
To:	Josef Bacik <jbacik@...hat.com>
Cc:	linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] jbd: fix assertion failure in journal_next_log_block

On Jan 31, 2008  11:14 -0500, Josef Bacik wrote:
[snip excellent analysis]
> So you get into this situation where
> t_nr_buffers (the actual number of buffers that are on the transaction) is
> greater than the number of buffers accounted for via t_outstanding_credits.
> This presents a problem since as we loop through writting buffers to the
> journal, we decrement t_outstanding_credits, and if t_nr_buffers is more than
> t_outstanding_credits then we end up with a negative number for
> t_outstanding_credits
> 
> Signed-off-by: Josef Bacik <jbacik@...hat.com>

Do you know what kernel this problem was introduced in, or is this a
long standing problem?  Presumably the same is needed for jbd2?

Once we have some decent amount of testing going on with ext4, I think
it makes sense to merge the jbd2 changes back into jbd and return to
a single code base, since there is nothing in the jbd2 code that ext3
can't also work with (i.e. all of the changes are properly isolated
with compatibility flags and such).

> @@ -1056,7 +1056,7 @@ static inline int jbd_space_needed(journal_t *journal)
>  	int nblocks = journal->j_max_transaction_buffers;
>  	if (journal->j_committing_transaction)
>  		nblocks += journal->j_committing_transaction->
> -					t_outstanding_credits;
> +					t_nr_buffers;

(trivial) this can be moved back onto the previous line.

> @@ -1168,7 +1168,7 @@ static inline int jbd_space_needed(journal_t *journal)
>  	int nblocks = journal->j_max_transaction_buffers;
>  	if (journal->j_committing_transaction)
>  		nblocks += journal->j_committing_transaction->
> -					t_outstanding_credits;
> +					t_nr_buffers;

Same...

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.

-
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html