ext4: Convert ext4_readpage_inline() to take a folio

Use the folio API in this function, saves a few calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20230324180129.1220691-10-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/ext4.h

@@ -3549,7 +3549,7 @@ extern int ext4_init_inline_data(handle_t *handle, struct inode *inode,
 				 unsigned int len);
 extern int ext4_destroy_inline_data(handle_t *handle, struct inode *inode);
 
-extern int ext4_readpage_inline(struct inode *inode, struct page *page);
+int ext4_readpage_inline(struct inode *inode, struct folio *folio);
 extern int ext4_try_to_write_inline_data(struct address_space *mapping,
 					 struct inode *inode,
 					 loff_t pos, unsigned len,

fs/ext4/inline.c

@@ -501,7 +501,7 @@ static int ext4_read_inline_page(struct inode *inode, struct page *page)
 	return ret;
 }
 
-int ext4_readpage_inline(struct inode *inode, struct page *page)
+int ext4_readpage_inline(struct inode *inode, struct folio *folio)
 {
 	int ret = 0;
 
@@ -515,16 +515,16 @@ int ext4_readpage_inline(struct inode *inode, struct page *page)
 	 * Current inline data can only exist in the 1st page,
 	 * So for all the other pages, just set them uptodate.
 	 */
-	if (!page->index)
-		ret = ext4_read_inline_page(inode, page);
-	else if (!PageUptodate(page)) {
-		zero_user_segment(page, 0, PAGE_SIZE);
-		SetPageUptodate(page);
+	if (!folio->index)
+		ret = ext4_read_inline_page(inode, &folio->page);
+	else if (!folio_test_uptodate(folio)) {
+		folio_zero_segment(folio, 0, folio_size(folio));
+		folio_mark_uptodate(folio);
 	}
 
 	up_read(&EXT4_I(inode)->xattr_sem);
 
-	unlock_page(page);
+	folio_unlock(folio);
 	return ret >= 0 ? 0 : ret;
 }
 

fs/ext4/inode.c

@@ -3155,7 +3155,7 @@ static int ext4_read_folio(struct file *file, struct folio *folio)
 	trace_ext4_readpage(page);
 
 	if (ext4_has_inline_data(inode))
-		ret = ext4_readpage_inline(inode, page);
+		ret = ext4_readpage_inline(inode, folio);
 
 	if (ret == -EAGAIN)
 		return ext4_mpage_readpages(inode, NULL, page);