From: Christoph Hellwig <hch@lst.de>
Date: Thu, 24 Sep 2020 06:51:37 +0000 (+0200)
Subject: mm: use SWP_SYNCHRONOUS_IO more intelligently
X-Git-Tag: v5.10-rc1~168^2~54
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=5115db10a8e0a525edf8a65b2ed4eac5c8253095;p=thirdparty%2Fkernel%2Fstable.git

mm: use SWP_SYNCHRONOUS_IO more intelligently

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>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/mm/page_io.c b/mm/page_io.c
index e485a6e8a6cdd..b199b87e0aa92 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;