[PATCH v15 12/17] iomap: Convert iomap_page_mkwrite to use a folio

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

If we write to any page in a folio, we have to mark the entire
folio as dirty, and potentially COW the entire folio, because it'll
all get written back as one unit.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/iomap/buffered-io.c | 41 +++++++++++++++++++++--------------------
 1 file changed, 21 insertions(+), 20 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index dfb2eec520bd..dd05db36e135 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -953,21 +953,22 @@ iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
 }
 EXPORT_SYMBOL_GPL(iomap_truncate_page);
 
-static loff_t
-iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
-		void *data, struct iomap *iomap, struct iomap *srcmap)
+static loff_t iomap_folio_mkwrite_actor(struct inode *inode, loff_t pos,
+		loff_t length, void *data, struct iomap *iomap,
+		struct iomap *srcmap)
 {
-	struct page *page = data;
+	struct folio *folio = data;
 	int ret;
 
 	if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
-		ret = __block_write_begin_int(page, pos, length, NULL, iomap);
+		ret = __block_write_begin_int(&folio->page, pos, length, NULL,
+						iomap);
 		if (ret)
 			return ret;
-		block_commit_write(page, 0, length);
+		block_commit_write(&folio->page, 0, length);
 	} else {
-		WARN_ON_ONCE(!PageUptodate(page));
-		set_page_dirty(page);
+		WARN_ON_ONCE(!folio_test_uptodate(folio));
+		folio_mark_dirty(folio);
 	}
 
 	return length;
@@ -975,33 +976,33 @@ iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
 
 vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops)
 {
-	struct page *page = vmf->page;
+	struct folio *folio = page_folio(vmf->page);
 	struct inode *inode = file_inode(vmf->vma->vm_file);
-	unsigned long length;
-	loff_t offset;
+	size_t length;
+	loff_t pos;
 	ssize_t ret;
 
-	lock_page(page);
-	ret = page_mkwrite_check_truncate(page, inode);
+	folio_lock(folio);
+	ret = folio_mkwrite_check_truncate(folio, inode);
 	if (ret < 0)
 		goto out_unlock;
 	length = ret;
 
-	offset = page_offset(page);
+	pos = folio_pos(folio);
 	while (length > 0) {
-		ret = iomap_apply(inode, offset, length,
-				IOMAP_WRITE | IOMAP_FAULT, ops, page,
-				iomap_page_mkwrite_actor);
+		ret = iomap_apply(inode, pos, length,
+				IOMAP_WRITE | IOMAP_FAULT, ops, folio,
+				iomap_folio_mkwrite_actor);
 		if (unlikely(ret <= 0))
 			goto out_unlock;
-		offset += ret;
+		pos += ret;
 		length -= ret;
 	}
 
-	wait_for_stable_page(page);
+	folio_wait_stable(folio);
 	return VM_FAULT_LOCKED;
 out_unlock:
-	unlock_page(page);
+	folio_unlock(folio);
 	return block_page_mkwrite_return(ret);
 }
 EXPORT_SYMBOL_GPL(iomap_page_mkwrite);
-- 
2.30.2