Re: [PATCH v3] md/r5cache: generate R5LOG_PAYLOAD_FLUSH

[Shaohua Li <shli@kernel.org>]

On Thu, Mar 09, 2017 at 09:23:39PM -0800, Song Liu wrote:
> In r5c_finish_stripe_write_out(), R5LOG_PAYLOAD_FLUSH is append to
> log->current_io.
> 
> Appending R5LOG_PAYLOAD_FLUSH in quiesce needs extra writes to
> journal. To simplify the logic, we just skip R5LOG_PAYLOAD_FLUSH in
> quiesce.
> 
> Even R5LOG_PAYLOAD_FLUSH supports multiple stripes per payload.
> However, current implementation is one stripe per R5LOG_PAYLOAD_FLUSH,
> which is simpler.

Thanks, applied the two patches.
 
> Signed-off-by: Song Liu <songliubraving@fb.com>
> ---
>  drivers/md/raid5-cache.c | 45 ++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 42 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
> index e69f922..e3c20c7 100644
> --- a/drivers/md/raid5-cache.c
> +++ b/drivers/md/raid5-cache.c
> @@ -591,7 +591,7 @@ static void r5l_log_endio(struct bio *bio)
>  
>  	spin_lock_irqsave(&log->io_list_lock, flags);
>  	__r5l_set_io_unit_state(io, IO_UNIT_IO_END);
> -	if (log->need_cache_flush)
> +	if (log->need_cache_flush && !list_empty(&io->stripe_list))
>  		r5l_move_to_end_ios(log);
>  	else
>  		r5l_log_run_stripes(log);
> @@ -619,9 +619,11 @@ static void r5l_log_endio(struct bio *bio)
>  			bio_endio(bi);
>  			atomic_dec(&io->pending_stripe);
>  		}
> -		if (atomic_read(&io->pending_stripe) == 0)
> -			__r5l_stripe_write_finished(io);
>  	}
> +
> +	/* finish flush only io_unit and PAYLOAD_FLUSH only io_unit */
> +	if (atomic_read(&io->pending_stripe) == 0)
> +		__r5l_stripe_write_finished(io);
>  }
>  
>  static void r5l_do_submit_io(struct r5l_log *log, struct r5l_io_unit *io)
> @@ -843,6 +845,41 @@ static void r5l_append_payload_page(struct r5l_log *log, struct page *page)
>  	r5_reserve_log_entry(log, io);
>  }
>  
> +static void r5l_append_flush_payload(struct r5l_log *log, sector_t sect)
> +{
> +	struct mddev *mddev = log->rdev->mddev;
> +	struct r5conf *conf = mddev->private;
> +	struct r5l_io_unit *io;
> +	struct r5l_payload_flush *payload;
> +	int meta_size;
> +
> +	/*
> +	 * payload_flush requires extra writes to the journal.
> +	 * To avoid handling the extra IO in quiesce, just skip
> +	 * flush_payload
> +	 */
> +	if (conf->quiesce)
> +		return;
> +
> +	mutex_lock(&log->io_mutex);
> +	meta_size = sizeof(struct r5l_payload_flush) + sizeof(__le64);
> +
> +	if (r5l_get_meta(log, meta_size)) {
> +		mutex_unlock(&log->io_mutex);
> +		return;
> +	}
> +
> +	/* current implementation is one stripe per flush payload */
> +	io = log->current_io;
> +	payload = page_address(io->meta_page) + io->meta_offset;
> +	payload->header.type = cpu_to_le16(R5LOG_PAYLOAD_FLUSH);
> +	payload->header.flags = cpu_to_le16(0);
> +	payload->size = cpu_to_le32(sizeof(__le64));
> +	payload->flush_stripes[0] = cpu_to_le64(sect);
> +	io->meta_offset += meta_size;
> +	mutex_unlock(&log->io_mutex);
> +}
> +
>  static int r5l_log_stripe(struct r5l_log *log, struct stripe_head *sh,
>  			   int data_pages, int parity_pages)
>  {
> @@ -2784,6 +2821,8 @@ void r5c_finish_stripe_write_out(struct r5conf *conf,
>  		atomic_dec(&conf->r5c_flushing_full_stripes);
>  		atomic_dec(&conf->r5c_cached_full_stripes);
>  	}
> +
> +	r5l_append_flush_payload(log, sh->sector);
>  }
>  
>  int
> -- 
> 2.9.3
> 
> --
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