On Nov 24, 2013, at 6:03 PM, NeilBrown wrote: > On Sun, 24 Nov 2013 17:30:43 -0600 Jonathan Brassow <jbrassow@xxxxxxxxxx> > wrote: > >> When commit 773ca82 was made in v3.12-rc1, it caused RAID4/5/6 devices >> that were created via device-mapper (dm-raid.c) to hang on creation. >> This is not necessarily the fault of that commit, but perhaps the way >> dm-raid.c was setting-up and activating devices. >> >> Device-mapper allows I/O and memory allocations in the constructor >> (i.e. raid_ctr()), but nominal and recovery I/O should not be allowed >> until a 'resume' is issued (i.e. raid_resume()). It has been problematic >> (at least in the past) to call mddev_resume before mddev_suspend was >> called, but this is how DM behaves - CTR then resume. To solve the >> problem, raid_ctr() was setting up the structures, calling md_run(), and >> then also calling mddev_suspend(). The stage was then set for raid_resume() >> to call mddev_resume(). >> >> Commit 773ca82 caused a change in behavior during raid5.c:run(). >> 'setup_conf->grow_stripes->grow_one_stripe' is called which creates the >> stripe cache and increments 'active_stripes'. >> 'grow_one_stripe->release_stripe' doesn't actually decrement 'active_stripes' >> anymore. The side effect of this is that when raid_ctr calls mddev_suspend, >> it waits for 'active_stripes' to reduce to 0 - which never happens. > > Hi Jon, > this sounds like the same bug that is fixed by > > commit ad4068de49862b083ac2a15bc50689bb30ce3e44 > Author: majianpeng <majianpeng@xxxxxxxxx> > Date: Thu Nov 14 15:16:15 2013 +1100 > > raid5: Use slow_path to release stripe when mddev->thread is null > > which is already en-route to 3.12.x. Could you check if it fixes the bug for > you? Sure, I'll check. Just reading the subject of the patch, I have high hopes. The slow path decrements 'active_stripes', which was causing the above problem... I'll make sure though. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
