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bug#68504: [PATCH v3] Add copy-on-write support to scm_copy_file.
From: |
Ludovic Courtès |
Subject: |
bug#68504: [PATCH v3] Add copy-on-write support to scm_copy_file. |
Date: |
Thu, 21 Mar 2024 15:23:33 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) |
Hi,
Tomas Volf <~@wolfsden.cz> skribis:
> Sure, I am willing to do my part. I managed to find this blog post[0], so
> after
> some minor troubles I did manage to get a VM with GNU/Hurd running. Next I
> will
> read up on copy_file_range and try to put together a patch.
It’s really just (service hurd-vm-service-type) on Guix System:
https://guix.gnu.org/manual/devel/en/html_node/Virtualization-Services.html#The-Hurd-in-a-Virtual-Machine
> Just to make sure, your idea here is exactly what? Always try to use
> copy_file_range before the regular copy? So the flow would be
>
> For 'always case:
>
> CoW ---fail--> FAIL
>
> For 'auto case:
>
> CoW ---fail--> copy_file_range ---fail--> current copy ---fail-->
> FAIL
>
> For 'never case:
>
> copy_file_range ---fail--> current copy ---fail--> FAIL
>
> Is that an accurate summary?
Yes, that’s exactly what I had in mind.
Actually it might be better to use sendfile(2), which is slightly less
generic but otherwise equivalent AFAICS, and which happens to have a
Hurd implementation in glibc.
Thanks for your help!
Ludo’.