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Date:   Sat, 13 Jun 2020 07:38:54 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     Amir Goldstein <amir73il@gmail.com>
Cc:     Mike Kravetz <mike.kravetz@oracle.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Linux MM <linux-mm@kvack.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        overlayfs <linux-unionfs@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Miklos Szeredi <miklos@szeredi.hu>,
        Colin Walters <walters@verbum.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        syzbot <syzbot+d6ec23007e951dadf3de@syzkaller.appspotmail.com>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: [PATCH v4 1/2] hugetlb: use f_mode & FMODE_HUGETLBFS to identify
 hugetlbfs files
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On Sat, Jun 13, 2020 at 09:53:24AM +0300, Amir Goldstein wrote:
> Currently, the only in-tree stacking fs are overlayfs and ecryptfs, but there
> are some out of tree implementations as well (shiftfs).
> So you may only take that option if you do not care about the combination
> of hugetlbfs with any of the above.

I could see shiftfs being interesting, maybe.  I don't really see
the usecase for layering overlayfs or ecryptfs on top of a ram-based
filesystem.