iomap: iomap_write_end cleanup

In iomap_write_end(), only call iomap_write_failed() on the byte range
that has failed.  This should improve code readability, but doesn't fix
an actual bug because iomap_write_failed() is called after updating the
file size here and it only affects the memory beyond the end of the
file.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: NDarrick J. Wong <djwong@kernel.org>
Signed-off-by: NDarrick J. Wong <djwong@kernel.org>

fs/iomap/buffered-io.c

@@ -734,7 +734,7 @@ static size_t iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len,
 	folio_put(folio);
 
 	if (ret < len)
-		iomap_write_failed(iter->inode, pos, len);
+		iomap_write_failed(iter->inode, pos + ret, len - ret);
 	return ret;
 }