[PATCH 09/12] mm: use SWP_SYNCHRONOUS_IO more intelligently

Christoph Hellwig
2020-09-10T20:55:20Z

There is no point in trying to call bdev_read_page if SWP_SYNCHRONOUS_IO
is not set, as the device won't support it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
mm/page_io.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/mm/page_io.c b/mm/page_io.c
index e485a6e8a6cddb..b199b87e0aa92b 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -403,15 +403,17 @@ int swap_readpage(struct page *page, bool synchronous)
goto out;
}

- ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
- if (!ret) {
- if (trylock_page(page)) {
- swap_slot_free_notify(page);
- unlock_page(page);
- }
+ if (sis->flags & SWP_SYNCHRONOUS_IO) {
+ ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
+ if (!ret) {
+ if (trylock_page(page)) {
+ swap_slot_free_notify(page);
+ unlock_page(page);
+ }

- count_vm_event(PSWPIN);
- goto out;
+ count_vm_event(PSWPIN);
+ goto out;
+ }
}

ret = 0;
--
2.28.0