Re: [PATCH 09/16] zram: directly call zram_read_page in writeback_store

[Sergey Senozhatsky <senozhatsky@chromium.org>]

On (23/04/04 17:05), Christoph Hellwig wrote:
> 
> writeback_store always reads a full page, so just call zram_read_page
> directly and bypass the boune buffer handling.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>

> ---
>  drivers/block/zram/zram_drv.c | 16 +++++-----------
>  1 file changed, 5 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 6187e41a346fd8..9d2b6ef4638903 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -54,9 +54,8 @@ static size_t huge_class_size;
>  static const struct block_device_operations zram_devops;
>  
>  static void zram_free_page(struct zram *zram, size_t index);
> -static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
> -				u32 index, int offset, struct bio *bio);
> -
> +static int zram_read_page(struct zram *zram, struct page *page, u32 index,
> +			  struct bio *bio, bool partial_io);
>  
>  static int zram_slot_trylock(struct zram *zram, u32 index)
>  {
> @@ -671,10 +670,6 @@ static ssize_t writeback_store(struct device *dev,
>  	}
>  
>  	for (; nr_pages != 0; index++, nr_pages--) {
> -		struct bio_vec bvec;
> -
> -		bvec_set_page(&bvec, page, PAGE_SIZE, 0);
> -
>  		spin_lock(&zram->wb_limit_lock);
>  		if (zram->wb_limit_enable && !zram->bd_wb_limit) {
>  			spin_unlock(&zram->wb_limit_lock);
> @@ -718,7 +713,7 @@ static ssize_t writeback_store(struct device *dev,
>  		/* Need for hugepage writeback racing */
>  		zram_set_flag(zram, index, ZRAM_IDLE);
>  		zram_slot_unlock(zram, index);
> -		if (zram_bvec_read(zram, &bvec, index, 0, NULL)) {
> +		if (zram_read_page(zram, page, index, NULL, false)) {

In theory we can call zram_read_from_zspool() here, but zram_read_page()
is fine with me.

>  			zram_slot_lock(zram, index);
>  			zram_clear_flag(zram, index, ZRAM_UNDER_WB);
>  			zram_clear_flag(zram, index, ZRAM_IDLE);
> @@ -729,9 +724,8 @@ static ssize_t writeback_store(struct device *dev,
>  		bio_init(&bio, zram->bdev, &bio_vec, 1,
>  			 REQ_OP_WRITE | REQ_SYNC);
>  		bio.bi_iter.bi_sector = blk_idx * (PAGE_SIZE >> 9);
> -
> -		bio_add_page(&bio, bvec.bv_page, bvec.bv_len,
> -				bvec.bv_offset);
> +		bio_add_page(&bio, page, PAGE_SIZE, 0);
> +	
>  		/*
>  		 * XXX: A single page IO would be inefficient for write
>  		 * but it would be not bad as starter.
> -- 
> 2.39.2
>