Subject: Re: bug#55724: cp --reflink=always failing when --reflink=auto reflinks successfully on OpenZFS

From: Paul Eggert <[email-masked]>
Date: Mon, 30 May 2022 16:31:40 -0700

On 5/30/22 08:04, Pádraig Brady wrote:
> Really the kernel has to behave appropriately there
> and not do the blanket assumption with EXDEV.

I agree. VFS should be willing to try a cross-filesystem FICLONE. Not 
only does copy_file_range not guarantee cloning; it is less efficient 
even when it does clone, due to the need to find the holes in the source 
file.