On 08/04/2016 11:53 AM, Hannes Reinecke wrote: > On 08/03/2016 06:55 PM, Bart Van Assche wrote: >> On 08/02/2016 05:40 PM, Mike Snitzer wrote: >>> But I asked you to run the v4.7 kernel patches I >>> pointed to _without_ any of your debug patches. >> >> I need several patches to fix bugs that are not related to the device >> mapper, e.g. "sched: Avoid that __wait_on_bit_lock() hangs" >> (https://lkml.org/lkml/2016/8/3/289). >> > Hmm. Can you test with this patch? > > diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c > index 7790a70..9daed03 100644 > --- a/drivers/md/dm-mpath.c > +++ b/drivers/md/dm-mpath.c > @@ -439,8 +439,7 @@ static int must_push_back(struct multipath *m) > { > return (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) || > ((test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) != > - test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags)) && > - dm_noflush_suspending(m->ti))); > + test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags))); > } > > /* > > Reasoning: > The original check for dm_noflush_suspending() was for bio-based > drivers, which needed to queue I/O within the device-mapper core. > So during suspend this I/O would keep a reference to the device-mapper > core and the table couldn't be swapped. > For request-based multipathing, however, the I/O is _never_ held within > the device-mapper core but rather pushed back to the request queue. > IE even for pushback the I/O will never hold a reference to the > device-mapper core, and the tables can be swapped irrespective of the > 'dm_noflush_suspend()' setting. > > Or that's the idea, at least :-) > > Yes Mike, I know, it's not going to work with bio-based multipathing. > But this is just for figuring out where the real issue is. > And indeed. multipathd is calling DM_SUSPEND _without_ the noflush_suspending flag. (On the grounds that originally it needed to flush all I/O from the device-mapper core). Which will be causing I/O errors if any I/O is executed after ->presuspend has been called. Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@xxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
