Re: Patch "bcache: only permit to recovery read error when cache device is clean" has been added to the 4.9-stable tree

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Nov 27, 2017 at 09:35:02AM -0800, Michael Lyle wrote:
> On Mon, Nov 27, 2017 at 9:01 AM, Jens Axboe <axboe@kernel.dk> wrote:
> 
> > On 11/27/2017 09:45 AM, Eddie Chapman wrote:
> > > On 27/11/17 16:06, gregkh@linuxfoundation.org wrote:
> > >>
> > >> This is a note to let you know that I've just added the patch titled
> > >>
> > >>      bcache: only permit to recovery read error when cache device is
> > clean
> >
> 
> 
> > > Hi Greg,
> > >
> > > This patch is an important fix for a possible data corruption issue, but
> > > it also introduces a bug that can produce read errors under certain
> > > circumstances. The issue introduced by this patch is not as severe as
> > > the issue it fixes, but can lead to e.g. upper layer fs remounting read
> > > only. In my environment upper layer handled it badly and indirectly
> > > resulted in data loss (not directly bcache's fault of course).
> > >
> > > Michael Lyle CC'd the stable list with a follow up fix for the issue
> > > introduced by this patch, on 24th Nov, subject "bcache: recover data
> > > from backing when data is clean".
> > >
> > > However, the followup fix is not in Linus' tree yet, only in Michael's.
> > > I guess that means you can't pick it up yet. Never-the-less I felt it
> > > important to point this out here.
> >
> > It's commit e393aa2446150536929140739f09c6ecbcbea7f0 in my tree and will
> > go upstream shortly - but yes, probably should not add this one, before
> > both can be pulled in.
> 
> 
> Thanks everyone for the quick reply on this.  I agree.

Ok, I've dropped this patch from all of the stable queues for now.

thanks,

greg k-h