From: Andrew Morton <akpm@osdl.org>

generic_unplug_device() is wrong for DM backnig devices.

So instead, mark every BIO as being `synchronous'.  It'll blow a little bit
more CPU, but that's OK, and the IO scheduling behaviour will be the same.

Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Jens Axboe <axboe@suse.de>
Cc: Laurent Riffard <laurent.riffard@free.fr>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 kernel/power/swap.c |    3 +--
 1 files changed, 1 insertion(+), 2 deletions(-)

diff -puN kernel/power/swap.c~swsusp-read-speedup-fix-fix-2 kernel/power/swap.c
--- a/kernel/power/swap.c~swsusp-read-speedup-fix-fix-2
+++ a/kernel/power/swap.c
@@ -217,7 +217,6 @@ static int wait_on_bio_chain(struct bio 
 	bio = *bio_chain;
 	if (bio == NULL)
 		return 0;
-	generic_unplug_device(bdev_get_queue(bio->bi_bdev));
 	while (bio) {
 		struct page *page;
 
@@ -430,7 +429,7 @@ static int submit(int rw, pgoff_t page_o
 		get_page(page);
 		bio->bi_private = *bio_chain;
 		*bio_chain = bio;
-		submit_bio(rw, bio);
+		submit_bio(rw | (1 << BIO_RW_SYNC), bio);
 	}
 	return 0;
 }
_