On Wed, Jul 04, 2012 at 12:53:54AM -0600, Daniel J Blueman wrote: > On 4 July 2012 13:19, Liu Bo <liubo2009@xxxxxxxxxxxxxx> wrote: > > On 07/04/2012 11:37 AM, Daniel J Blueman wrote: > >>> Hi everyone, > >>> > >>> I've got a nice set of fixes from Josef, Jan, Ilya and others in my > >>> for-linus branch: > >>> > >>> git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs.git for-linus > >>> > >>> Some of the changes are fixes for the tree logging code, so I ran some > >>> extra crash runs against them Friday night. > >>> > >>> I ended up with a new crash in the tree log directory deletion replay > >>> code, so I didn't send out the pull request to Linus. > >>> > >>> It isn't clear yet if the new crash is because I was testing differently > >>> or if it is a regression. I'm nailing it down this weekend, but please > >>> give my for-linus a shot. > >> > >> I consistently run into this assertion [1] while running a fio > >> workload on a fresh RAID10 filesystem with a balance running. > >> > >> Let me know if you need steps to reproduce, debug etc. > > > > Seems that additional condition does not catch the bug. > > > > Plz show us the steps to reproduce, I'll try to reproduce it locally and nail it down. > > The reproducer auto-generated from my test [1] consistently hits the > spot here; config @ http://quora.org/2012/kconfig-btrfs . You'll need > the fio workload file [2] in the same dir. > Well that was a huge pain in the ass, you are going to have to tell me how to fix this Arne or fix it yourself. The problem was introduced here 00f04b88791ff49dc64ada18819d40a5b0671709 The problem is we no longer merge delayed refs on the fs trees anymore, and somehow we end up with this sequence of events alloc block add backref for some random block remove implicit backref add implicit backref back <-- I'm not entirely sure why/how this happens, I just assume its some relocate magic run refs because we do the sequence thing we go to add the implicit backref and panic because we find there is one already there, and that's not supposed to happen with tree blocks. If we had run the remove first we would have been fine or if we had just merged the delayed refs they would have cancelled each other out and we would have been fine. In order to test this theory I took the seq comparisons out of comp_entry in delayed-refs.c and the test has been running for about 20 minutes, before it would die in less than 30 seconds. So why is this needed? I assume you need it for something, but I figure its easier for you to fix this than for me to go figure out what it's used for. Thanks, Josef -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
