Re: [PATCH 30/35] btrfs: cleanup pending bgs on transaction abort

Josef Bacik
2018-08-31T18:14:52Z

On Fri, Aug 31, 2018 at 10:48:58AM +0300, Nikolay Borisov wrote:
>
>
> On 30.08.2018 20:42, Josef Bacik wrote:
> > We may abort the transaction during a commit and not have a chance to
> > run the pending bgs stuff, which will leave block groups on our list and
> > cause us accounting issues and leaked memory. Fix this by running the
> > pending bgs when we cleanup a transaction.
> >
> > Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> > ---
> > fs/btrfs/transaction.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
> > index 89d14f135837..0f39a0d302d3 100644
> > --- a/fs/btrfs/transaction.c
> > +++ b/fs/btrfs/transaction.c
> > @@ -2273,6 +2273,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
> > btrfs_scrub_continue(fs_info);
> > cleanup_transaction:
> > btrfs_trans_release_metadata(trans);
> > + btrfs_create_pending_block_groups(trans);
>
> And now you've basically hi-jacked btrfs_create_pending_block_groups to
> just act as "delete all bg" in case transaction is aborted. Considering
> this and the previous patch I'd rather you replace them with a single
> one which introduces a new function delete_pending_bgs or whatever and
> use that. This will be more explicit and self-documenting.
>

I haven't hi-jacked it and I'm not adding another helper when we already have
code that does the right thing. Remember if we abort a transaction in a path
that doesn't commit we still end up calling btrfs_create_pending_block_groups()
in btrfs_end_transaction which does the cleanup there, I'm not adding a bunch of
new code for a case that's easily handled with the previous fix and works the
same way in other paths. Thanks,

Josef