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Date:   Tue, 28 Mar 2023 13:00:30 +0900
From:   Josh Triplett <josh@joshtriplett.org>
To:     Linus Torvalds <torvalds@linux-foundation.org>
CC:     Christian Brauner <brauner@kernel.org>,
        Pedro Falcato <pedro.falcato@gmail.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] do_open(): Fix O_DIRECTORY | O_CREAT behavior
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On March 28, 2023 12:32:59 PM GMT+09:00, Linus Torvalds <torvalds@linux-fou=
ndation=2Eorg> wrote:
>Ok, just to play along - maybe you can make it slightly less
>nonsensical by throwing O_PATH into the mix, and now an empty
>directory file descriptor at least has *some* use=2E

That's the case I was thinking of: create a directory, then use exclusivel=
y *at system calls, never anything path-based=2E (I was using "atomic" loos=
ely; not concerned about races here, just convenience=2E)

>Now your code would not only be specific to Linux, it would be
>specific to some very new version of Linux, and do something
>completely different on older versions=2E

I'm extremely not concerned with depending on current Linux=2E But that sa=
id=2E=2E=2E

>Because those older versions will do random things, ranging from
>"always return an error" to "create a regular file - not a directory -
>and then return an error anyway" and finally "create a regular file -
>not a directory - and return that resulting fd"=2E

=2E=2E=2E Right, open has the un-extendable semantics, hence O_TMPFILE=2E =
Fair enough=2E Nevermind then=2E

As is often the case for multi-operation syscalls, I'm better off just usi=
ng io_uring for a mkdir-then-open=2E