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Date:   Thu, 9 Feb 2023 12:33:00 -0800
From:   Jeremy Allison <jra@samba.org>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Stefan Metzmacher <metze@samba.org>, Jens Axboe <axboe@kernel.dk>,
        Linux API Mailing List <linux-api@vger.kernel.org>,
        Samba Technical <samba-technical@lists.samba.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        io-uring <io-uring@vger.kernel.org>
Subject: Re: copy on write for splice() from file to pipe?
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Reply-To: Jeremy Allison <jra@samba.org>
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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.