Re: [PATCH 03/12] writeback: move dirty inodes from super_block to backing_dev_info

[Jan Kara <jack@suse.cz>]

On Mon 25-05-09 09:34:38, Jens Axboe wrote:
> This is a first step at introducing per-bdi flusher threads. We should
> have no change in behaviour, although sb_has_dirty_inodes() is now
> ridiculously expensive, as there's no easy way to answer that question.
> Not a huge problem, since it'll be deleted in subsequent patches.
> 
> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
> ---
>  fs/fs-writeback.c           |  196 +++++++++++++++++++++++++++---------------
>  fs/super.c                  |    3 -
>  include/linux/backing-dev.h |    9 ++
>  include/linux/fs.h          |    5 +-
>  mm/backing-dev.c            |   30 +++++++
>  mm/page-writeback.c         |   11 +--
>  6 files changed, 170 insertions(+), 84 deletions(-)
...
> @@ -225,9 +231,23 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
>  }
>  EXPORT_SYMBOL(bdi_register_dev);
>  
> +static void bdi_remove_from_list(struct backing_dev_info *bdi)
> +{
> +	mutex_lock(&bdi_lock);
> +	list_del_rcu(&bdi->bdi_list);
> +	mutex_unlock(&bdi_lock);
> +
> +	/*
> +	 * In case the bdi is freed right after unregister, we need to
> +	 * make sure any RCU sections have exited
> +	 */
> +	synchronize_rcu();
> +}
> +
  Is this RCU thing still valid? And in bdi_register_dev() as well...

									Honza

-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR