ext4: remove unnecessary wbc parameter from ext4_bio_write_page

ext4_bio_write_page does not need wbc parameter, since its parameter
io contains the io_wbc field. The io::io_wbc is initialized by
ext4_io_submit_init which is called in ext4_writepages and
ext4_writepage functions prior to ext4_bio_write_page.
Therefor, when ext4_bio_write_page is called, wbc info
has already been included in io parameter.

Signed-off-by: Lei Chen <lennychen@tencent.com>
Link: https://lore.kernel.org/r/1607669664-25656-1-git-send-email-lennychen@tencent.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/ext4.h

@@ -3653,7 +3653,6 @@ extern void ext4_io_submit(struct ext4_io_submit *io);
 extern int ext4_bio_write_page(struct ext4_io_submit *io,
 			       struct page *page,
 			       int len,
-			       struct writeback_control *wbc,
 			       bool keep_towrite);
 extern struct ext4_io_end_vec *ext4_alloc_io_end_vec(ext4_io_end_t *io_end);
 extern struct ext4_io_end_vec *ext4_last_io_end_vec(ext4_io_end_t *io_end);

fs/ext4/inode.c

@@ -2064,7 +2064,7 @@ static int ext4_writepage(struct page *page,
 		unlock_page(page);
 		return -ENOMEM;
 	}
-	ret = ext4_bio_write_page(&io_submit, page, len, wbc, keep_towrite);
+	ret = ext4_bio_write_page(&io_submit, page, len, keep_towrite);
 	ext4_io_submit(&io_submit);
 	/* Drop io_end reference we got from init */
 	ext4_put_io_end_defer(io_submit.io_end);
@@ -2098,7 +2098,7 @@ static int mpage_submit_page(struct mpage_da_data *mpd, struct page *page)
 		len = size & ~PAGE_MASK;
 	else
 		len = PAGE_SIZE;
-	err = ext4_bio_write_page(&mpd->io_submit, page, len, mpd->wbc, false);
+	err = ext4_bio_write_page(&mpd->io_submit, page, len, false);
 	if (!err)
 		mpd->wbc->nr_to_write--;
 	mpd->first_page++;

fs/ext4/page-io.c

@@ -435,7 +435,6 @@ static void io_submit_add_bh(struct ext4_io_submit *io,
 int ext4_bio_write_page(struct ext4_io_submit *io,
 			struct page *page,
 			int len,
-			struct writeback_control *wbc,
 			bool keep_towrite)
 {
 	struct page *bounce_page = NULL;
@@ -445,6 +444,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 	int ret = 0;
 	int nr_submitted = 0;
 	int nr_to_submit = 0;
+	struct writeback_control *wbc = io->io_wbc;
 
 	BUG_ON(!PageLocked(page));
 	BUG_ON(PageWriteback(page));