Ilya Dryomov wrote (ao): > On Thu, Mar 29, 2012 at 12:52:35PM +0200, Sander wrote: > > After a reboot, I tried again, with the same result: > > > > [ 81.048767] ------------[ cut here ]------------ > > [ 81.053619] kernel BUG at fs/btrfs/volumes.c:2733! > > [ 81.053619] Internal error: Oops - BUG: 0 [#1] SMP > > [ 81.059295] Modules linked in: > > [ 81.059295] CPU: 1 Not tainted (3.3.0 #8) > > [ 81.071411] PC is at btrfs_balance+0x312/0xb04 > > [ 81.074890] LR is at btrfs_run_delayed_iputs+0x2d/0xac
> So you have balance item on disk, but the kernel doesn't seem to know > about it in advance, which is odd and so when you try to run balance it > panics on one of the safety checks. > > > The system is a pandaboard running a plain Linus kernel 3.3.0 with a > > btrfs filesystem, over two Intel 320 600GB ssd's, connected via usb (on > > an usb hub), on top of md_crypt. Mount options: > > "subvol=rootvolume,space_cache,inode_cache,compress=lzo,ssd" > > > > Before the balance, I deleted about 2500 snapshots and waited for the > > btrfs kernel threads to calm down. Then I initiated a btrfs filesystem > > scrub. Unfortunately during the scrub, the filesystem balance started. > > Might be related. > > That's indeed pretty cool, I wonder how that could happen. I create 5 snapshots of 5 different subvolumes every 5 minutes, and the system is low on memory: total used free shared buffers cached Mem: 745 712 33 0 0 480 -/+ buffers/cache: 231 514 Swap: 0 0 0 There is ample space on the fileystem: panda:~# df -h / Filesystem Size Used Avail Use% Mounted on /dev/mapper/ata-INTEL_SSDSA2CW600G3_CVPR112405AJ600FGN 1.1T 17G 1.1T 2% / panda:~# btrfs filesystem df / Data, RAID0: total=24.00GB, used=15.69GB System, RAID1: total=64.00MB, used=12.00KB System: total=4.00MB, used=0.00 Metadata, RAID1: total=23.00GB, used=231.26MB Do you need more information? > I'm definitely intrested in reproducing it. Could you please umount this > filesystem, capture the output of 'btrfs-debug-tree -d <dev>' and post it > somewhere ? Will do. It is the / filesystem, so I'll need to reboot. > After that mount it back and see if there is "btrfs: continuing > balance" line in dmesg (and if btrfs-balance kthread shows up)? There was none after the first reboot, but I'll pay extra attention to that after the next reboot. > If so, just let it run, it should finish the balance and remove > on-disk item. (You can query the status of running balance with 'btrfs > balance status <mnt>') Do I need newer tools for that? This is Debian Sid (unstable): Btrfs Btrfs v0.19 panda:~# btrfs filesystem balance status / ERROR: 'filesystem balance' requires 1 arg(s) panda:~# btrfs balance status / ERROR: unknown command 'balance' Usage: .. -- Humilis IT Services and Solutions http://www.humilis.net -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html