Re: [PATCH 2/3] libceph: add function to ensure notifies are complete

[Alex Elder <alex.elder@linaro.org>]

On 08/29/2013 01:24 AM, Josh Durgin wrote:
> Without a way to flush the osd client's notify workqueue, a watch
> event that is unregistered could continue receiving callbacks
> indefinitely.
> 
> Unregistering the event simply means no new notifies are added to the
> queue, but there may still be events in the queue that will call the
> watch callback for the event. If the queue is flushed after the event
> is unregistered, the caller can be sure no more watch callbacks will
> occur for the canceled watch.

Looks good.

Reviewed-by: Alex Elder <elder@linaro.org>

> Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
> ---
>  include/linux/ceph/osd_client.h |    2 ++
>  net/ceph/osd_client.c           |   11 +++++++++++
>  2 files changed, 13 insertions(+), 0 deletions(-)
> 
> diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
> index ce6df39..8f47625 100644
> --- a/include/linux/ceph/osd_client.h
> +++ b/include/linux/ceph/osd_client.h
> @@ -335,6 +335,8 @@ extern int ceph_osdc_wait_request(struct ceph_osd_client *osdc,
>  				  struct ceph_osd_request *req);
>  extern void ceph_osdc_sync(struct ceph_osd_client *osdc);
>  
> +extern void ceph_osdc_flush_notifies(struct ceph_osd_client *osdc);
> +
>  extern int ceph_osdc_readpages(struct ceph_osd_client *osdc,
>  			       struct ceph_vino vino,
>  			       struct ceph_file_layout *layout,
> diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
> index 1606f74..2b4b32a 100644
> --- a/net/ceph/osd_client.c
> +++ b/net/ceph/osd_client.c
> @@ -2216,6 +2216,17 @@ void ceph_osdc_sync(struct ceph_osd_client *osdc)
>  EXPORT_SYMBOL(ceph_osdc_sync);
>  
>  /*
> + * Call all pending notify callbacks - for use after a watch is
> + * unregistered, to make sure no more callbacks for it will be invoked
> + */
> +extern void ceph_osdc_flush_notifies(struct ceph_osd_client *osdc)
> +{
> +	flush_workqueue(osdc->notify_wq);
> +}
> +EXPORT_SYMBOL(ceph_osdc_flush_notifies);
> +
> +
> +/*
>   * init, shutdown
>   */
>  int ceph_osdc_init(struct ceph_osd_client *osdc, struct ceph_client *client)
>