Re: [PATCH 11/11] writeback: add comments to bdi_work structure

[Jan Kara]

On Tue 15-09-09 20:16:57, Jens Axboe wrote:
> And document its retriever, get_next_work_item().
> 
> Signed-off-by: Jens Axboe <jens.axboe@xxxxxxxxxx>
  Acked-by: Jan Kara <jack@xxxxxxx>

							Honza

> ---
>  fs/fs-writeback.c |   18 +++++++++++-------
>  1 files changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> index 3de93a9..6e199ef 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -49,15 +49,15 @@ struct wb_writeback_args {
>   * Work items for the bdi_writeback threads
>   */
>  struct bdi_work {
> -	struct list_head list;
> -	struct rcu_head rcu_head;
> +	struct list_head list;		/* pending work list */
> +	struct rcu_head rcu_head;	/* for RCU free/clear of work */
>  
> -	unsigned long seen;
> -	atomic_t pending;
> +	unsigned long seen;		/* threads that have seen this work */
> +	atomic_t pending;		/* number of threads still to do work */
>  
> -	struct wb_writeback_args args;
> +	struct wb_writeback_args args;	/* writeback arguments */
>  
> -	unsigned long state;
> +	unsigned long state;		/* flag bits, see WS_* */
>  };
>  
>  enum {
> @@ -758,7 +758,11 @@ static long wb_writeback(struct bdi_writeback *wb,
>  
>  /*
>   * Return the next bdi_work struct that hasn't been processed by this
> - * wb thread yet
> + * wb thread yet. ->seen is initially set for each thread that exists
> + * for this device, when a thread first notices a piece of work it
> + * clears its bit. Depending on writeback type, the thread will notify
> + * completion on either receiving the work (WB_SYNC_NONE) or after
> + * it is done (WB_SYNC_ALL).
>   */
>  static struct bdi_work *get_next_work_item(struct backing_dev_info *bdi,
>  					   struct bdi_writeback *wb)
> -- 
> 1.6.4.1.207.g68ea
> 
-- 
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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