On Thu, Mar 03, 2016 at 04:17:24AM +0000, Eric Wheeler wrote:
> On Fri, 26 Feb 2016, Eric Wheeler wrote:
> > On Fri, 26 Feb 2016, Marc MERLIN wrote:
> >
> > > On Fri, Feb 26, 2016 at 04:55:02AM +0000, Eric Wheeler wrote:
> > > > According to Documentation/bcache.txt:
> > > > "" If you're booting up and your cache device is gone and never
> > > > coming back, you can force run the backing device:
> > > > echo 1 > /sys/block/sdb/bcache/running
> > > > [...]
> > > > The backing device will still use that cache set if it shows up
> > > > in the future, but all the cached data will be invalidated. ""
> > > >
> > > > So it seems that you are safe. (It would be interesting to know how it
> > > > invalidates the cache. Maybe bumps the Set UUID? Not sure.)
> > >
> > > Yeah, that was my understanding too, but I wanted to make sure.
> > > Strangely (worringly so?) the cache was replayed at boot, and this time
> > > nothing crashed, or any traceback.
> > > Now I'm wondering if it pushed garbage onto my filesystem :-/
> >
> > I'm not convinced that journal replay will writeback, especially because
> > of the documentation stating that forcing a bdev into a running state
> > invalidates its cache. I think it just keeps the datastructures in good
> > shape on the cachedev, even though the cachedev was invalidated by forcing
> > a 'running' state.
>
> Hi Marc,
>
> Thank you for your help investigating. The two patches resulting from our
> testing are on their way into 4.5.
I saw that, thank you.
> How has it been running since? Any new backtraces to investigate?
No crashes since then, although my last one started when I was shutting
the laptop down, and I don't shut down very often (actually virtually
never unless I upgrade kernels :) ).
But that's another way ot say so far so good :)
Thanks for your work looking into this.
Marc
--
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
.... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/ | PGP 1024R/763BE901
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