[dm-devel] [PATCH 16/22] dm: Refactor for new bio cloning/splitting

[Kent Overstreet]

On Sun, Oct 06, 2013 at 08:14:10PM -0400, Mike Snitzer wrote:
> On Fri, Oct 04 2013 at  1:07pm -0400,
> Mike Snitzer <snitzer at redhat.com> wrote:
>  
> > With your latest fix I was able to create a thin device and format with
> > XFS.  Unfortunately, when I tried to run the thinp-test-suite the very
> > first BasicTests test (test_dd_benchmark) fails -- need to look closer
> > but it would seem to me the thinp saved bio_endio path isn't happy.  We
> > likely need an appropriately placed atomic_inc(&bio->bi_remaining); like
> > you did in dm-cache-target.c
> > 
> > ------------[ cut here ]------------
> > kernel BUG at fs/bio.c:1722!
> ...
> > Call Trace:
> >  [<ffffffffa05f2ef9>] process_prepared_mapping+0x79/0x150 [dm_thin_pool]
> >  [<ffffffffa05f2ba7>] process_prepared+0x87/0xa0 [dm_thin_pool]
> >  [<ffffffffa05f58f3>] do_worker+0x33/0x60 [dm_thin_pool]
> >  [<ffffffff81067862>] process_one_work+0x182/0x3b0
> >  [<ffffffff81068c80>] worker_thread+0x120/0x3a0
> >  [<ffffffff81068b60>] ? manage_workers+0x160/0x160
> >  [<ffffffff8106eace>] kthread+0xce/0xe0
> >  [<ffffffff8106ea00>] ? kthread_freezable_should_stop+0x70/0x70
> >  [<ffffffff8152b1ac>] ret_from_fork+0x7c/0xb0
> >  [<ffffffff8106ea00>] ? kthread_freezable_should_stop+0x70/0x70
> > Code: 1f 84 00 00 00 00 00 48 8b 57 10 83 e2 01 0f 44 f1 eb cd 0f 1f 40 00 48 8b 7f 50 48 85 ff 74 dd 8b 57 44 48 8d 47 44 85 d2 7f ac <0f> 0b eb fe 0f 1f 84 00 00 00 00 00 55 48 89 e5 66 66 66 66 90 
> > RIP  [<ffffffff811b1464>] bio_endio+0x74/0x80
> >  RSP <ffff88032c5e7d48>
> > ---[ end trace acb5a7d638591b7b ]---
> 
> Please fold this fix into your for-jens branch, thanks.  (Could be that
> by the time Jens takes your immutable biovec changes we'll need to
> rebase but at least it won't slip through the cracks).

Thanks! I knew that bio chaining patch was going to cause a few issues
like this, but it seems to useful to pass up. Anything else come up/any
comments?