linux-kernel - Re: [PATCH 00/67] fscache: Rewrite index API and management system

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Message-ID: <CAH2r5msO7-QCXv6JQj2Tado9ZoWAHRkgq6-En18PeKSXFDdBLw@mail.gmail.com>
Date:   Thu, 21 Oct 2021 18:15:49 -0500
From:   Steve French <smfrench@...il.com>
To:     Omar Sandoval <osandov@...ndov.com>
Cc:     David Howells <dhowells@...hat.com>, linux-cachefs@...hat.com,
        ceph-devel <ceph-devel@...r.kernel.org>,
        linux-afs@...ts.infradead.org,
        Anna Schumaker <anna.schumaker@...app.com>,
        linux-nfs <linux-nfs@...r.kernel.org>,
        Kent Overstreet <kent.overstreet@...il.com>,
        linux-mm <linux-mm@...ck.org>,
        Matthew Wilcox <willy@...radead.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Dave Wysochanski <dwysocha@...hat.com>,
        Marc Dionne <marc.dionne@...istor.com>,
        Trond Myklebust <trond.myklebust@...merspace.com>,
        Shyam Prasad N <nspmangalore@...il.com>,
        Eric Van Hensbergen <ericvh@...il.com>,
        v9fs-developer@...ts.sourceforge.net,
        CIFS <linux-cifs@...r.kernel.org>,
        Latchesar Ionkov <lucho@...kov.net>,
        Jeff Layton <jlayton@...nel.org>,
        Steve French <sfrench@...ba.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Dominique Martinet <asmadeus@...ewreck.org>,
        Ilya Dryomov <idryomov@...il.com>,
        Trond Myklebust <trondmy@...merspace.com>,
        Jeff Layton <jlayton@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 00/67] fscache: Rewrite index API and management system

On Thu, Oct 21, 2021 at 5:21 PM Omar Sandoval <osandov@...ndov.com> wrote:
>
> On Mon, Oct 18, 2021 at 03:50:15PM +0100, David Howells wrote:
> However, with the advent of the tmpfile capacity in the VFS, an opportunity
> arises to do invalidation much more easily, without having to wait for I/O
> that's actually in progress: Cachefiles can simply cut over its file
> pointer for the backing object attached to a cookie and abandon the
> in-progress I/O, dismissing it upon completion.

Have changes been made to O_TMPFILE?  It is problematic for network filesystems
because it is not an atomic operation, and would be great if it were possible
to create a tmpfile and open it atomically (at the file system level).

Currently it results in creating a tmpfile (which results in
opencreate then close)
immediately followed by reopening the tmpfile which is somewhat counter to
the whole idea of a tmpfile (ie that it is deleted when closed) since
the syscall results
in two opens ie open(create)/close/open/close


-- 
Thanks,

Steve