linux-kernel - Re: [GIT PULL] Btrfs updates for 5.8, part 2

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Date:   Mon, 15 Jun 2020 14:40:26 +0100
From:   Filipe Manana <fdmanana@...il.com>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     dsterba@...e.cz, Linus Torvalds <torvalds@...ux-foundation.org>,
        David Sterba <dsterba@...e.com>,
        linux-btrfs <linux-btrfs@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [GIT PULL] Btrfs updates for 5.8, part 2

On Mon, Jun 15, 2020 at 2:29 PM Christoph Hellwig <hch@...radead.org> wrote:
>
> On Mon, Jun 15, 2020 at 02:57:01PM +0200, David Sterba wrote:
> > On Sun, Jun 14, 2020 at 09:50:17AM -0700, Linus Torvalds wrote:
> > > On Sun, Jun 14, 2020 at 4:56 AM David Sterba <dsterba@...e.com> wrote:
> > > >
> > > > Reverts are not great, but under current circumstances I don't see
> > > > better options.
> > >
> > > Pulled. Are people discussing how to make iomap work for everybody?
> > > It's a bit sad if we can't have the major filesystems move away from
> > > the old buffer head interfaces to a common more modern one..
> >
> > Yes, it's fixable and we definitely want to move to iomap. The direct to
> > buffered fallback would fix one of the problems, but this would also
> > mean that xfs would start doing that. Such change should be treated more
> > like a feature development than a bugfix, imposed by another filesystem,
> > and xfs people rightfully complained.
>
> We can trivially key that off a flag at least for 5.8.  I suspect the
> fallback actually is the right thing for XFS in the long run for that
> particular case.

We also have another regression (a deadlock) [1] introduced by the patchset.
I haven't looked into detail to figure out if it can be completely
solved in btrfs or if it would need a change on iomap.
Goldwyn was looking into it, but I don't know if he made any progress.

[1] https://lore.kernel.org/linux-btrfs/CAL3q7H4F9iQJy3tgwZrWOKwenAnnn7oSthQZUMEJ_vWx3WE3WQ@mail.gmail.com/#t

-- 
Filipe David Manana,

“Whether you think you can, or you think you can't — you're right.”