[RFC PATCH v2 2/5] mm: Remove the callback func argument from __swap_writepage()

[David Howells <dhowells@redhat.com>]

Remove the callback func argument from __swap_writepage() as it's
end_swap_bio_write() in both places that call it.

This reverts:

	commit 1eec6702a80e04416d528846a5ff2122484d95ec
	mm: allow for outstanding swap writeback accounting

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Matthew Wilcox (Oracle) <willy@infradead.org>
cc: Seth Jennings <sjenning@linux.vnet.ibm.com>
cc: Bob Liu <bob.liu@oracle.com>
cc: Minchan Kim <minchan@kernel.org>
cc: Dan Magenheimer <dan.magenheimer@oracle.com>
---

 include/linux/swap.h |    4 +---
 mm/page_io.c         |    9 ++++-----
 mm/zswap.c           |    2 +-
 3 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 81801ba78b1e..b785bb041a44 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -425,9 +425,7 @@ extern void kswapd_stop(int nid);
 /* linux/mm/page_io.c */
 extern int swap_readpage(struct page *page, bool do_poll);
 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
-extern void end_swap_bio_write(struct bio *bio);
-extern int __swap_writepage(struct page *page, struct writeback_control *wbc,
-	bio_end_io_t end_write_func);
+extern int __swap_writepage(struct page *page, struct writeback_control *wbc);
 extern int swap_set_page_dirty(struct page *page);
 
 int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
diff --git a/mm/page_io.c b/mm/page_io.c
index edb72bf624d2..62cabcdfcec6 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -26,7 +26,7 @@
 #include <linux/uio.h>
 #include <linux/sched/task.h>
 
-void end_swap_bio_write(struct bio *bio)
+static void end_swap_bio_write(struct bio *bio)
 {
 	struct page *page = bio_first_page_all(bio);
 
@@ -249,7 +249,7 @@ int swap_writepage(struct page *page, struct writeback_control *wbc)
 		end_page_writeback(page);
 		goto out;
 	}
-	ret = __swap_writepage(page, wbc, end_swap_bio_write);
+	ret = __swap_writepage(page, wbc);
 out:
 	return ret;
 }
@@ -282,8 +282,7 @@ static void bio_associate_blkg_from_page(struct bio *bio, struct page *page)
 #define bio_associate_blkg_from_page(bio, page)		do { } while (0)
 #endif /* CONFIG_MEMCG && CONFIG_BLK_CGROUP */
 
-int __swap_writepage(struct page *page, struct writeback_control *wbc,
-		bio_end_io_t end_write_func)
+int __swap_writepage(struct page *page, struct writeback_control *wbc)
 {
 	struct bio *bio;
 	int ret;
@@ -342,7 +341,7 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,
 	bio_set_dev(bio, sis->bdev);
 	bio->bi_iter.bi_sector = swap_page_sector(page);
 	bio->bi_opf = REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc);
-	bio->bi_end_io = end_write_func;
+	bio->bi_end_io = end_swap_bio_write;
 	bio_add_page(bio, page, thp_size(page), 0);
 
 	bio_associate_blkg_from_page(bio, page);
diff --git a/mm/zswap.c b/mm/zswap.c
index 7944e3e57e78..f38e34917aa3 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1011,7 +1011,7 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
 	SetPageReclaim(page);
 
 	/* start writeback */
-	__swap_writepage(page, &wbc, end_swap_bio_write);
+	__swap_writepage(page, &wbc);
 	put_page(page);
 	zswap_written_back_pages++;