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Message-ID: <352f587fe4e24a8bea5f841b5f93df92164072d0.camel@themaw.net>
Subject: Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency
 improvement
From:   Ian Kent <raven@themaw.net>
To:     Tejun Heo <tj@kernel.org>
Cc:     Greg KH <gregkh@linuxfoundation.org>,
        Fox Chen <foxhlchen@gmail.com>, akpm@linux-foundation.org,
        dhowells@redhat.com, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, miklos@szeredi.hu,
        ricklind@linux.vnet.ibm.com, sfr@canb.auug.org.au,
        viro@zeniv.linux.org.uk
Date:   Sun, 20 Dec 2020 09:37:42 +0800
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On Sun, 2020-12-20 at 07:52 +0800, Ian Kent wrote:
> On Sat, 2020-12-19 at 11:23 -0500, Tejun Heo wrote:
> > Hello,
> > 
> > On Sat, Dec 19, 2020 at 03:08:13PM +0800, Ian Kent wrote:
> > > And looking further I see there's a race that kernfs can't do
> > > anything
> > > about between kernfs_refresh_inode() and
> > > fs/inode.c:update_times().
> > 
> > Do kernfs files end up calling into that path tho? Doesn't look
> > like
> > it to
> > me but if so yeah we'd need to override the update_time for kernfs.

You are correct, update_time() will only be called during symlink
following and only to update atime.

So this isn't sufficient to update the inode attributes to reflect
changes make by things like kernfs_setattr() or when the directory
link count changes ...

Sigh!