From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Mason Subject: Re: Crash in __btrfs_reserve_extent Date: Thu, 6 Aug 2009 15:22:19 -0400 Message-ID: <20090806192219.GD17129@think> References: <4A7A9A04.5010006@redpill-linpro.com> <20090806135436.GD3655@dhcp231-156.rdu.redhat.com> <4A7AE579.1050403@redpill-linpro.com> <20090806142750.GE3655@dhcp231-156.rdu.redhat.com> <4A7B15DD.2010101@redpill-linpro.com> <20090806180432.GG3655@dhcp231-156.rdu.redhat.com> <4A7B1D6D.6090402@redpill-linpro.com> <20090806183712.GH3655@dhcp231-156.rdu.redhat.com> <4A7B25C3.4020206@redpill-linpro.com> <20090806190118.GI3655@dhcp231-156.rdu.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Tore Anderson , linux-btrfs@vger.kernel.org, Hugo Mills To: Josef Bacik Return-path: In-Reply-To: <20090806190118.GI3655@dhcp231-156.rdu.redhat.com> List-ID: On Thu, Aug 06, 2009 at 03:01:18PM -0400, Josef Bacik wrote: > On Thu, Aug 06, 2009 at 08:49:39PM +0200, Tore Anderson wrote: > > * Josef Bacik > > > > > Ok good news is, btrfs-vol -b will fix your problem. Somehow most of > > > your disk has been allocated to use metadata. So did you have a > > > whole bunch of stuff on this disk and then delete it all? Because > > > that would put you in that situation. If you have not then there is > > > likely a bug in the metadata ratio stuff that needs to be fixed. > > > > As far as I know there hasn't been a lot of stuff on the file system, > > I'm afraid. The file system was created by the Fedora 11 installer, > > and it has just been used as the system drive (I've got /home on NFS). > > > > btrfs-vol -b / (from btrfs-progs-0.19) made my system crash and burn. > > I've was able to get output from dmesg before my SSH sessions started > > hanging - maybe you can make anything out of it? Anyway, right now I > > have no more remote access to the box so any further debugging will > > have to wait until tomorrow morning. > > > > Hrm yeah I was afraid of that. So you will have to try and free up some data so > the balancer as enough room to move things around. Also one thing that _may_ > help is mounting with nocow for a little bit, so any writing (like logging and > such) just over-writes stuff instead of needing a new extent, until btrfs-vol -b > can finish, and then you can go back to the normal mount options. I still can't > figure out how this happened, but one thing to do for now would be to mount with > metadata_ratio=100. This will make you more likely to panic in the event that > you run out of metadata, but its not that likely to happen, especially with as > much disk space as you have. Sorry about all of this, hopefully a better > solution will be coming down in a few months. Thanks, We can code a fix for the balancer problem quickly, but you might have a hard time recompiling it and getting it on that box. If this data is critical we'll write something up. -chris