[PATCH v2 06/10] mm/swap: use npage_to_sectors() and PAGE_SECTORS to clean up code

From: Zhen Lei
Date: Thu May 07 2020 - 03:56:05 EST


1. Replace "<<= (PAGE_SHIFT - 9)" with "*= PAGE_SECTORS"
2. Replace "<< (PAGE_SHIFT - 9)" with npage_to_sectors()

Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
---
mm/page_io.c | 4 ++--
mm/swapfile.c | 12 ++++++------
2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/mm/page_io.c b/mm/page_io.c
index 76965be1d40e..23291a49ab91 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -38,7 +38,7 @@ static struct bio *get_swap_bio(gfp_t gfp_flags,

bio->bi_iter.bi_sector = map_swap_page(page, &bdev);
bio_set_dev(bio, bdev);
- bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9;
+ bio->bi_iter.bi_sector *= PAGE_SECTORS;
bio->bi_end_io = end_io;

bio_add_page(bio, page, PAGE_SIZE * hpage_nr_pages(page), 0);
@@ -266,7 +266,7 @@ int swap_writepage(struct page *page, struct writeback_control *wbc)

static sector_t swap_page_sector(struct page *page)
{
- return (sector_t)__page_file_index(page) << (PAGE_SHIFT - 9);
+ return npage_to_sectors((sector_t)__page_file_index(page));
}

static inline void count_swpout_vm_event(struct page *page)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 5871a2aa86a5..c8be92f972a4 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -177,8 +177,8 @@ static int discard_swap(struct swap_info_struct *si)

/* Do not discard the swap header page! */
se = first_se(si);
- start_block = (se->start_block + 1) << (PAGE_SHIFT - 9);
- nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9);
+ start_block = npage_to_sectors(se->start_block + 1);
+ nr_blocks = npage_to_sectors((sector_t)se->nr_pages - 1);
if (nr_blocks) {
err = blkdev_issue_discard(si->bdev, start_block,
nr_blocks, GFP_KERNEL, 0);
@@ -188,8 +188,8 @@ static int discard_swap(struct swap_info_struct *si)
}

for (se = next_se(se); se; se = next_se(se)) {
- start_block = se->start_block << (PAGE_SHIFT - 9);
- nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9);
+ start_block = npage_to_sectors(se->start_block);
+ nr_blocks = npage_to_sectors((sector_t)se->nr_pages);

err = blkdev_issue_discard(si->bdev, start_block,
nr_blocks, GFP_KERNEL, 0);
@@ -240,8 +240,8 @@ static void discard_swap_cluster(struct swap_info_struct *si,
start_page += nr_blocks;
nr_pages -= nr_blocks;

- start_block <<= PAGE_SHIFT - 9;
- nr_blocks <<= PAGE_SHIFT - 9;
+ start_block *= PAGE_SECTORS;
+ nr_blocks *= PAGE_SECTORS;
if (blkdev_issue_discard(si->bdev, start_block,
nr_blocks, GFP_NOIO, 0))
break;
--
2.26.0.106.g9fadedd