linux-kernel - Re: [PATCH v5 0/3] FUSE: Implement atomic lookup + open/create

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Message-ID: <CAJfpegsJijCeNZ9ES72e=gDNDisK5itG67GK8xNWRar=HMm6gA@mail.gmail.com>
Date:   Thu, 19 May 2022 20:16:11 +0200
From:   Miklos Szeredi <miklos@...redi.hu>
To:     Bernd Schubert <bschubert@....com>
Cc:     Dharmendra Singh <dharamhans87@...il.com>,
        Vivek Goyal <vgoyal@...hat.com>, linux-fsdevel@...r.kernel.org,
        fuse-devel <fuse-devel@...ts.sourceforge.net>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 0/3] FUSE: Implement atomic lookup + open/create

On Thu, 19 May 2022 at 19:42, Bernd Schubert <bschubert@....com> wrote:

> Can you help me a bit to understand what we should change? I had also
> already thought to merge CREATE_EXT and OPEN_ATOMIC - so agreed.
> Shall we make the other cases more visible?

Make it clear in the code flow if we are using the new request or the
old; e.g. rename current fuse_atomic_open() to fuse_open_nonatomic()
and do

static int fuse_open_atomic(...)
{
    ...
    args.opcode = FUSE_OPEN_ATOMIC;
    ...
    err = fuse_simple_request(...);
    if (err == -ENOSYS)
        goto fallback;
    ...
fallback:
    return fuse_open_nonatomic();
}

static int fuse_atomic_open(...)
{
    if (fc->no_open_atomic)
        return fuse_open_nonatomic();
    else
        return fuse_open_atomic();
}

Also we can tweak fuse_dentry_revalidate() so it always invalidates
negative dentries if the new atomic open is available, and possibly
for positive dentries as well, if the rfc patch makes it.

Thanks,
Miklos