[PATCH 05/31] ext4: Convert ext4_writepage() to use a folio

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

Prepare for multi-page folios and save some instructions by converting
to the folio API.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/ext4/inode.c | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index b8b3e2e0d9fd..8e3d2cca1e0c 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2027,26 +2027,25 @@ static int ext4_writepage(struct page *page,
 
 	trace_ext4_writepage(page);
 	size = i_size_read(inode);
-	if (page->index == size >> PAGE_SHIFT &&
+	len = folio_size(folio);
+	if (folio_pos(folio) + len > size &&
 	    !ext4_verity_in_progress(inode))
-		len = size & ~PAGE_MASK;
-	else
-		len = PAGE_SIZE;
+		len = size - folio_pos(folio);
 
+	page_bufs = folio_buffers(folio);
 	/* Should never happen but for bugs in other kernel subsystems */
-	if (!page_has_buffers(page)) {
+	if (!page_bufs) {
 		ext4_warning_inode(inode,
-		   "page %lu does not have buffers attached", page->index);
-		ClearPageDirty(page);
-		unlock_page(page);
+		   "page %lu does not have buffers attached", folio->index);
+		folio_clear_dirty(folio);
+		folio_unlock(folio);
 		return 0;
 	}
 
-	page_bufs = page_buffers(page);
 	/*
 	 * We cannot do block allocation or other extent handling in this
 	 * function. If there are buffers needing that, we have to redirty
-	 * the page. But we may reach here when we do a journal commit via
+	 * the folio. But we may reach here when we do a journal commit via
 	 * journal_submit_inode_data_buffers() and in that case we must write
 	 * allocated buffers to achieve data=ordered mode guarantees.
 	 *
@@ -2062,7 +2061,7 @@ static int ext4_writepage(struct page *page,
 	 */
 	if (ext4_walk_page_buffers(NULL, inode, page_bufs, 0, len, NULL,
 				   ext4_bh_delay_or_unwritten)) {
-		redirty_page_for_writepage(wbc, page);
+		folio_redirty_for_writepage(wbc, folio);
 		if ((current->flags & PF_MEMALLOC) ||
 		    (inode->i_sb->s_blocksize == PAGE_SIZE)) {
 			/*
@@ -2072,12 +2071,12 @@ static int ext4_writepage(struct page *page,
 			 */
 			WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD))
 							== PF_MEMALLOC);
-			unlock_page(page);
+			folio_unlock(folio);
 			return 0;
 		}
 	}
 
-	if (PageChecked(page) && ext4_should_journal_data(inode))
+	if (folio_test_checked(folio) && ext4_should_journal_data(inode))
 		/*
 		 * It's mmapped pagecache.  Add buffers and journal it.  There
 		 * doesn't seem much point in redirtying the page here.
@@ -2087,8 +2086,8 @@ static int ext4_writepage(struct page *page,
 	ext4_io_submit_init(&io_submit, wbc);
 	io_submit.io_end = ext4_init_io_end(inode, GFP_NOFS);
 	if (!io_submit.io_end) {
-		redirty_page_for_writepage(wbc, page);
-		unlock_page(page);
+		folio_redirty_for_writepage(wbc, folio);
+		folio_unlock(folio);
 		return -ENOMEM;
 	}
 	ret = ext4_bio_write_page(&io_submit, page, len);
-- 
2.35.1