Re: [PATCH 1/6] writeback: fix writeback completion notifications

[Jens Axboe <axboe@kernel.dk>]

On 08/06/10 18.14, Christoph Hellwig wrote:
> The code dealing with bdi_work->state and completion of a bdi_work is a
> major mess currently.  This patch makes sure we directly use one set of
> flags to deal with it, and use it consistently, which means:
> 
>  - always notify about completion from the rcu callback.  We only ever
>    wait for it from on-stack callers, so this simplification does not
>    even cause a theoretical slowdown currently.  It also makes sure we
>    don't miss out on the notification if we ever add other callers to
>    wait for it.

It's still more costly to actually do the rcu callback, but I guess it's
not too big of a deal.

>  - make earlier completion notification depending on the on-stack
>    allocation, not the sync mode.  If we introduce new callers that
>    want to do WB_SYNC_NONE writeback from on-stack callers this will
>    be nessecary.
> 
> Also rename bdi_wait_on_work_clear to bdi_wait_on_work_done and inline
> a few small functions into their only caller to make the code
> understandable.

Looks good to me.

-- 
Jens Axboe