Received-SPF: pass (google.com: domain of linux-ext4-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Mon, 11 Jan 2021 11:50:27 -0800
From:   Eric Biggers <ebiggers@kernel.org>
To:     Christoph Hellwig <hch@lst.de>
Cc:     linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
        linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net,
        Theodore Ts'o <tytso@mit.edu>
Subject: Re: [PATCH v2 04/12] fat: only specify I_DIRTY_TIME when needed in
 fat_update_time()
Message-ID: <X/ysA8PuJ/+JXQYL@sol.localdomain>
References: <20210109075903.208222-1-ebiggers@kernel.org>
 <20210109075903.208222-5-ebiggers@kernel.org>
 <20210111105201.GB2502@lst.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20210111105201.GB2502@lst.de>
Precedence: bulk

On Mon, Jan 11, 2021 at 11:52:01AM +0100, Christoph Hellwig wrote:
> On Fri, Jan 08, 2021 at 11:58:55PM -0800, Eric Biggers wrote:
> > +	if ((flags & S_VERSION) && inode_maybe_inc_iversion(inode, false))
> > +		dirty_flags |= I_DIRTY_SYNC;
> 
> fat does not support i_version updates, so this bit can be skipped.

Is that really the case?  Any filesystem (including fat) can be mounted with
"iversion", which causes SB_I_VERSION to be set.

A lot of filesystems (including fat) don't store i_version to disk, but it looks
like it will still get updated in-memory.  Could anything be relying on that?

- Eric