linux-kernel - Re: [PATCH] open: make RESOLVE_CACHED correctly test for O

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Date:   Sat, 5 Aug 2023 19:21:41 +0200
From:   Christian Brauner <brauner@...nel.org>
To:     Aleksa Sarai <cyphar@...har.com>, Jens Axboe <axboe@...nel.dk>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, Alexander Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH] open: make RESOLVE_CACHED correctly test for O_TMPFILE

On Sat, Aug 05, 2023 at 07:17:54PM +0200, Christian Brauner wrote:
> On Sun, 06 Aug 2023 02:11:58 +1000, Aleksa Sarai wrote:
> > O_TMPFILE is actually __O_TMPFILE|O_DIRECTORY. This means that the old
> > fast-path check for RESOLVE_CACHED would reject all users passing
> > O_DIRECTORY with -EAGAIN, when in fact the intended test was to check
> > for __O_TMPFILE.

And afaict, io_uring has the same problem in

static bool io_openat_force_async(struct io_open *open)
{
        /*
         * Don't bother trying for O_TRUNC, O_CREAT, or O_TMPFILE open,
         * it'll always -EAGAIN
         */
        return open->how.flags & (O_TRUNC | O_CREAT | O_TMPFILE);
}

always forcing O_DIRECTORY lookups to go async. So that needs another
fix.