btrfs: make end_extent_writepage return void

Does not return any errors, nor anything from the callgraph.  The branch
in end_bio_extent_writepage has been skipped since
5fd02043553b ("Btrfs: finish ordered extents in their own thread").

Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index b7261ea..0ea3e99 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2515,7 +2515,7 @@
 
 /* lots and lots of room for performance fixes in the end_bio funcs */
 
-int end_extent_writepage(struct page *page, int err, u64 start, u64 end)
+void end_extent_writepage(struct page *page, int err, u64 start, u64 end)
 {
 	int uptodate = (err == 0);
 	struct extent_io_tree *tree;
@@ -2536,7 +2536,6 @@
 		ret = ret < 0 ? ret : -EIO;
 		mapping_set_error(page->mapping, ret);
 	}
-	return 0;
 }
 
 /*
@@ -2578,9 +2577,7 @@
 		start = page_offset(page);
 		end = start + bvec->bv_offset + bvec->bv_len - 1;
 
-		if (end_extent_writepage(page, bio->bi_error, start, end))
-			continue;
-
+		end_extent_writepage(page, bio->bi_error, start, end);
 		end_page_writeback(page);
 	}