copy on write for splice() from file to pipe?

[Jeremy Allison]

On Thu, Feb 09, 2023 at 11:48:35AM -0800, Linus Torvalds via samba-technical wrote:
>
>So this is exactly *why* splicing from a file all the way to the
>network will then show any file changes that have happened in between
>that "splice started" and "network card got the data". You're supposed
>to use splice only when you can guarantee the data stability (or,
>alternatively, when you simply don't care about the data stability,
>and getting the changed data is perfectly fine).

Metze, correct me if I'm wrong but isn't this exactly the "file
is leased in SMB3" case ?

We already know if a file is leased, and so only use the splice calls
for I/O in that case, and fall back to the slower calls in the
non-leased case.