linux-kernel - Re: [GIT PULL] overlayfs update for 4.18

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Date:   Sun, 10 Jun 2018 23:09:50 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Christoph Hellwig <hch@...radead.org>,
        Miklos Szeredi <miklos@...redi.hu>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        linux-unionfs@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [GIT PULL] overlayfs update for 4.18

On Sat, Jun 09, 2018 at 02:42:20PM -0700, Linus Torvalds wrote:
> And Christoph's copmmentary isn't really helping the situation.
> Christoph, I haven't seen the NAK history, can you elaborate?

Most of the bits just need a bit of refinement I think, instead of
being forced through the overlayfs tree and are generally fine.

The pre_mmap hook I think is a clear no-go.  We've had this tried
multiple times and always rejected it.  Unlike previous uses the
overlayfs use isn't outright broken, but still questionalable
as it will still lead to a copyup that "leaks" if the actual mmap
wasn't successfull.  The whole discussion of how mmap happens,
how we deal with mmap_sem and failures needs a broader discussion
with all MM and VFS folks first.