GNU bug report logs - #60416
Be more liberal using copy_file_range() with NFS mounted filesystems

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From: Pádraig Brady <P <at> draigBrady.com>
To: Paul Eggert <eggert <at> cs.ucla.edu>, Braiam <braiamp <at> gmail.com>, 60416-done <at> debbugs.gnu.org
Subject: bug#60416: [PATCH] copy: attempt copy offload with sparse files
Date: Sat, 31 Dec 2022 12:04:27 +0000

On 31/12/2022 01:36, Paul Eggert wrote:
> On 2022-12-30 16:23, Pádraig Brady wrote:
>>
>> I may follow up with a related patch to
>> ensure we _don't_ use copy_file_range with --sparse=never.
> 
> Not sure it's worth the bother. A file system that would create holes
> with copy_file_range could also do so with plain 'write', no?

Well copy_file_range() would be lower level and within its
remit to propagate holes. The FreeBSD docs allude to this also.

But yes, our use of copy_file_range() is generally restricted
to non holes, so less of an issue for us.

Also there may be users using `cp --sparse=never` to avoid
the perf issue currently, like we saw on the OP web thread.

I'll hold off on that change so.

Hopefully copy_file_range() flags are introduced to give
control over this (like I suggested on lkml years ago).

cheers,
Pádraig

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