On Thu, Feb 16, 2012 at 07:55:15PM +0600, Roman Mamedov wrote:

  5813                 BUG_ON(!(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));

I was unable to make netconsole work over a bridged interface, so can only
post screenshots of this OOPS:
  http://romanrm.ru/pics/2012/2012-02-16-btrfs-bug-1.jpg
  http://romanrm.ru/pics/2012/2012-02-16-btrfs-bug-2.jpg

This happened four times already, and always on snapshot creation (but not
every case). I have hourly snapshots in crontab, and only one case out of about
ten fails with this problem. Did not try to deliberately reproduce it yet by
manually making snapshots very often, etc.

I've hit a different bug with

* a process doing random reads/writes to a file
* looped toggling of NOCOW flag on the file every 10 seconds
* snapshotting of the fs every 10 seconds

and it triggered after a few minutes. It's an ENOSPC at

920         btrfs_i_size_write(parent_inode, parent_inode->i_size +
921                                          dentry->d_name.len * 2);
922         ret = btrfs_update_inode(trans, parent_root, parent_inode);
923         BUG_ON(ret);


[49220.539979] ------------[ cut here ]------------
[49220.543580] kernel BUG at fs/btrfs/transaction.c:923!
[49220.543580] invalid opcode: 0000 [#1] SMP
[49220.543580] CPU 0
[49220.543580] Modules linked in: btrfs aoe [last unloaded: btrfs]
[49220.543580]
[49220.543580] Pid: 12646, comm: btrfs Not tainted 3.2.0-default+ #114 Intel Corporation Santa Rosa platform/Matanzas
[49220.543580] RIP: 0010:[<ffffffffa01086da>]  [<ffffffffa01086da>] create_pending_snapshot+0x4ca/0x4d0 [btrfs]
[49220.543580] RSP: 0018:ffff880000869b48  EFLAGS: 00010286
[49220.543580] RAX: 00000000ffffffe4 RBX: ffff8800191afdf8 RCX: ffff88000e8679d8
[49220.543580] RDX: ffff88006cddd440 RSI: ffffffff8187d42d RDI: 0000000000000246
[49220.543580] RBP: ffff880000869c08 R08: 0000000000000000 R09: 0000000000000000
[49220.543580] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8800347b6740
[49220.543580] R13: ffff880054eb5180 R14: ffff880062b56000 R15: ffff880078f45510
[49220.543580] FS:  00007f6637f5c740(0000) GS:ffff88007dc00000(0000) knlGS:0000000000000000
[49220.543580] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[49220.543580] CR2: 00007f80a26c7000 CR3: 000000001edad000 CR4: 00000000000006f0
[49220.543580] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[49220.543580] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[49220.543580] Process btrfs (pid: 12646, threadinfo ffff880000868000, task ffff88006cddd440)
[49220.543580] Stack:
[49220.543580]  ffff880000000002 0000000000000083 ffff880078394000 ffff8800105d8390
[49220.543580]  ffff88001016bcd0 ffff880062b56000 ffff88007a15e070 ffff8800105d8390
[49220.543580]  ffff880079c14000 ffff8800347b6758 0000000000000175 ffffffffffffff84
[49220.543580] Call Trace:
[49220.543580]  [<ffffffffa00e65fa>] ? btrfs_free_path+0x2a/0x40 [btrfs]
[49220.543580]  [<ffffffffa0108726>] create_pending_snapshots+0x46/0x70 [btrfs]
[49220.543580]  [<ffffffffa0109a57>] btrfs_commit_transaction+0x3e7/0x8d0 [btrfs]
[49220.543580]  [<ffffffff81077aa0>] ? wake_up_bit+0x40/0x40
[49220.543580]  [<ffffffff81357eee>] ? do_raw_spin_unlock+0x5e/0xb0
[49220.543580]  [<ffffffffa0139e48>] btrfs_mksubvol+0x358/0x360 [btrfs]
[49220.543580]  [<ffffffffa0139f50>] btrfs_ioctl_snap_create_transid+0x100/0x160 [btrfs]
[49220.543580]  [<ffffffff81113f73>] ? might_fault+0x53/0xb0
[49220.543580]  [<ffffffffa013a12d>] btrfs_ioctl_snap_create_v2.clone.0+0xfd/0x110 [btrfs]
[49220.543580]  [<ffffffffa013ba47>] btrfs_ioctl+0x4a7/0x1270 [btrfs]
[49220.543580]  [<ffffffff81883400>] ? do_page_fault+0x2d0/0x580
[49220.543580]  [<ffffffff8187f150>] ? _raw_spin_unlock_irq+0x30/0x50
[49220.543580]  [<ffffffff8103ff23>] ? finish_task_switch+0x83/0xf0
[49220.543580]  [<ffffffff8103fee6>] ? finish_task_switch+0x46/0xf0
[49220.543580]  [<ffffffff8114d5e8>] do_vfs_ioctl+0x98/0x560
[49220.543580]  [<ffffffff8108b7a9>] ? trace_hardirqs_off_caller+0x29/0xc0
[49220.543580]  [<ffffffff8187f919>] ? retint_swapgs+0x13/0x1b
[49220.543580]  [<ffffffff8114daff>] sys_ioctl+0x4f/0x80
[49220.543580]  [<ffffffff81887c02>] system_call_fastpath+0x16/0x1b
[49220.543580] Code: 75 fd ff ff 0f 1f 44 00 00 0f b7 16 83 e8 02 48 83 c6 02 66 89 17 48 83 c7 02 e9 64 fd ff ff 0f 0b 0f 0b 0f 0b 0f 0b 0f 0b 0f 0b <0f> 0b 0f 1f 40 00 55 48 89 e5 41 56 41 55 41 54 53 66 66 66 66
[49220.543580] RIP  [<ffffffffa01086da>] create_pending_snapshot+0x4ca/0x4d0 [btrfs]
[49220.543580]  RSP <ffff880000869b48>
[49220.937724] ---[ end trace 8f8b8a074f8e75d4 ]---