[dm-devel] Bcache upstreaming

[Kent Overstreet]

On Wed, Jan 30, 2013 at 05:27:47PM -0800, Kent Overstreet wrote:
> On Wed, Jan 30, 2013 at 05:26:27PM -0800, Kent Overstreet wrote:
> > On Wed, Jan 30, 2013 at 07:10:21PM -0500, Mike Snitzer wrote:
> > > On Wed, Jan 30 2013 at  6:36pm -0500,
> > > Kent Overstreet <koverstreet at google.com> wrote:
> > > 
> > > > On Thu, Jan 17, 2013 at 03:41:04AM -0800, Kent Overstreet wrote:
> > > > > On Wed, Jan 16, 2013 at 09:27:28PM -0500, Mike Snitzer wrote:
> > > > > > On Mon, Jan 14 2013 at  5:53pm -0500,
> > > > > > Mike Snitzer <snitzer at redhat.com> wrote:
> > > > > > 
> > > > > > > On Mon, Jan 14 2013 at  5:37pm -0500,
> > > > > > > Kent Overstreet <koverstreet at google.com> wrote:
> > > > > > > 
> > > > > > > > Want to try again with the latest bcache-for-upstream branch? I fixed
> > > > > > > > all that sysfs stuff, but I wasn't seeing the original build error so
> > > > > > > > I'd appreciate if you verify I did in fact fix that issue.
> > > > > > > 
> > > > > > > Will do, thanks Kent.
> > > > > > 
> > > > > > I hit the crash below if I do this in a script:
> > > > > > 
> > > > > > echo 1 > /sys/block/bcache0/bcache/cache/unregister
> > > > > > echo 1 > /sys/block/bcache0/bcache/stop
> > > > > 
> > > > > Thanks - I reproduced it, trying to figure out the sanest way to fix it.
> > > > > This is not the prettiest area of the code :P
> > > > 
> > > > And, I finally have a fix for it up.
> > > > 
> > > > Fixed a bunch of other bugs today too... notably the bug where it'd
> > > > crash if you enabled discards. Was there anything else you or anyone
> > > > else was hitting?
> > > 
> > > Great, thanks, the other outstanding report was this one:
> > > https://lkml.org/lkml/2013/1/17/554
> > 
> > Yep, that was the discard bug I just fixed.
> 
> Err I misread - nope, I missed that one. Taking a look now.

Fucking shrinkers, i swear that's one of the most nonsensical APIs I've
yet encountered.

This is going to take some thought. For now, just disable the shrinker:

echo 1 > /sys/fs/bcache/<uuid>/internal/btree_shrinker_disabled