From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jes Sorensen Subject: Re: Bad raid0 bio too large problem Date: Wed, 23 Sep 2015 07:20:55 -0400 Message-ID: References: <87k2rhyiqe.fsf@notabene.neil.brown.name> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: (Jes Sorensen's message of "Wed, 23 Sep 2015 07:18:11 -0400") Sender: linux-raid-owner@vger.kernel.org To: Neil Brown Cc: Xiao Ni , linux-raid , yizhan@redhat.com List-Id: linux-raid.ids Jes Sorensen writes: > Neil Brown writes: >> Jes Sorensen writes: >> >>> Hi Neil, >>> >>> I think we have some bad side effects with this patch: >>> >>> commit 199dc6ed5179251fa6158a461499c24bdd99c836 >>> Author: NeilBrown >>> Date: Mon Aug 3 13:11:47 2015 +1000 >>> >>> md/raid0: update queue parameter in a safer location. >>> >>> When a (e.g.) RAID5 array is reshaped to RAID0, the updating >>> of queue parameters (e.g. max number of sectors per bio) is >>> done in the wrong place. >>> It should be part of ->run, but it is actually part of ->takeover. >>> This means it happens before level_store() calls: >>> >>> blk_set_stacking_limits(&mddev->queue->limits); >>> >>> Running the '03r0assem' test suite fills my kernel log with output like >>> below. Yi Zhang also had issues where writes failed too. >>> >>> robably something we need to resolve for 4.2-final or revert the >>> offending patch. >>> >>> Cheers, >>> Jes >>> >>> md: bind >>> md: bind >>> md: bind >>> md/raid0:md2: md_size is 116736 sectors. >>> md: RAID0 configuration for md2 - 1 zone >>> md: zone0=[loop0/loop1/loop2] >>> zone-offset= 0KB, device-offset= 0KB, size= 58368KB >>> >>> md2: detected capacity change from 0 to 59768832 >>> bio too big device loop0 (296 > 255) >>> bio too big device loop0 (272 > 255) >> >> 1/ Why do you blame that particular patch? >> >> 2/ Where is that error message coming from? I cannot find "bio too big" >> in the kernel (except in a comment). >> Commit: 54efd50bfd87 ("block: make generic_make_request handle >> arbitrarily sized bios") >> removed the only instance of the error message that I know of. >> >> Which kernel exactly are you testing? > > I blame it because of bisect - I revert that patch and the issue goes > away. > > I checked out 199dc6ed5179251fa6158a461499c24bdd99c836 in Linus' tree, > see the bio too large. I revert it and it goes away. Hmmm Xiao tells me that the warning message is not in upstream, but I was sure I reproduced it in the upstream kernel as well. If I screwed up, my apologies, I am going back to my cave and will investigate further. Jes