btrfs: utilize folio more in btrfs_page_mkwrite()

We already have a folio that we're using in btrfs_page_mkwrite, update
the rest of the function to use folio everywhere else. This will make
it easier on Willy when he drops page->index.

Signed-off-by: Josef Bacik <[e-mail]>
Reviewed-by: David Sterba <[e-mail]>
Signed-off-by: David Sterba <[e-mail]>

fs/btrfs/file.c

···
 	reserved_space = PAGE_SIZE;
 
 	sb_start_pagefault(inode->i_sb);
-	page_start = page_offset(page);
-	page_end = page_start + PAGE_SIZE - 1;
+	page_start = folio_pos(folio);
+	page_end = page_start + folio_size(folio) - 1;
 	end = page_end;
 
 	/*
···
 	ret = VM_FAULT_NOPAGE;
 again:
 	down_read(&BTRFS_I(inode)->i_mmap_lock);
-	lock_page(page);
+	folio_lock(folio);
 	size = i_size_read(inode);
 
-	if ((page->mapping != inode->i_mapping) ||
+	if ((folio->mapping != inode->i_mapping) ||
 	    (page_start >= size)) {
 		/* Page got truncated out from underneath us. */
 		goto out_unlock;
 	}
-	wait_on_page_writeback(page);
+	folio_wait_writeback(folio);
 
 	lock_extent(io_tree, page_start, page_end, &cached_state);
-	ret2 = set_page_extent_mapped(page);
+	ret2 = set_folio_extent_mapped(folio);
 	if (ret2 < 0) {
 		ret = vmf_error(ret2);
 		unlock_extent(io_tree, page_start, page_end, &cached_state);
···
 	ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), page_start, PAGE_SIZE);
 	if (ordered) {
 		unlock_extent(io_tree, page_start, page_end, &cached_state);
-		unlock_page(page);
+		folio_unlock(folio);
 		up_read(&BTRFS_I(inode)->i_mmap_lock);
 		btrfs_start_ordered_extent(ordered);
 		btrfs_put_ordered_extent(ordered);
 		goto again;
 	}
 
-	if (page->index == ((size - 1) >> PAGE_SHIFT)) {
+	if (folio->index == ((size - 1) >> PAGE_SHIFT)) {
 		reserved_space = round_up(size - page_start, fs_info->sectorsize);
 		if (reserved_space < PAGE_SIZE) {
 			end = page_start + reserved_space - 1;
···
 	}
 
 	/* Page is wholly or partially inside EOF. */
-	if (page_start + PAGE_SIZE > size)
-		zero_start = offset_in_page(size);
+	if (page_start + folio_size(folio) > size)
+		zero_start = offset_in_folio(folio, size);
 	else
 		zero_start = PAGE_SIZE;
 
 	if (zero_start != PAGE_SIZE)
-		memzero_page(page, zero_start, PAGE_SIZE - zero_start);
+		folio_zero_range(folio, zero_start, folio_size(folio) - zero_start);
 
 	btrfs_folio_clear_checked(fs_info, folio, page_start, PAGE_SIZE);
 	btrfs_folio_set_dirty(fs_info, folio, page_start, end + 1 - page_start);
···
 	return VM_FAULT_LOCKED;
 
 out_unlock:
-	unlock_page(page);
+	folio_unlock(folio);
 	up_read(&BTRFS_I(inode)->i_mmap_lock);
 out:
 	btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);