linux-kernel - Re: [PATCH 1/6] mm/fs: don't allow writes to immutable files

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Message-ID: <20190621005420.GH4650@mit.edu>
Date:   Thu, 20 Jun 2019 20:54:20 -0400
From:   "Theodore Ts'o" <tytso@....edu>
To:     "Darrick J. Wong" <darrick.wong@...cle.com>
Cc:     matthew.garrett@...ula.com, yuchao0@...wei.com,
        ard.biesheuvel@...aro.org, josef@...icpanda.com, clm@...com,
        adilger.kernel@...ger.ca, viro@...iv.linux.org.uk, jack@...e.com,
        dsterba@...e.com, jaegeuk@...nel.org, jk@...abs.org,
        reiserfs-devel@...r.kernel.org, linux-efi@...r.kernel.org,
        devel@...ts.orangefs.org, linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net, linux-xfs@...r.kernel.org,
        linux-mm@...ck.org, linux-nilfs@...r.kernel.org,
        linux-mtd@...ts.infradead.org, ocfs2-devel@....oracle.com,
        linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-btrfs@...r.kernel.org
Subject: Re: [PATCH 1/6] mm/fs: don't allow writes to immutable files

On Thu, Jun 20, 2019 at 03:13:06PM -0700, Darrick J. Wong wrote:
> > I note that this patch doesn't allow writes to swap files.  So Amir's
> > generic/554 test will still fail for those file systems that don't use
> > copy_file_range.
> 
> I didn't add any IS_SWAPFILE checks here, so I'm not sure to what you're
> referring?

Sorry, my bad; I mistyped.  What I should have said is this patch
doesn't *prohibit* writes to swap files....

(And so Amir's generic/554 test, even modified so it allow reads from
swapfiles, but not writes, when using copy_file_range, is still
failing for ext4.  I was looking to see if I could remove it from my
exclude list, but not yet.  :-)

> > I'm indifferent as to whether you add a new patch, or include that
> > change in this patch, but perhaps we should fix this while we're
> > making changes in these code paths?
> 
> The swapfile patches should be in a separate patch, which I was planning
> to work on but hadn't really gotten around to it.

Ok, great, thanks!!

				- Ted