ktrace.log

[  721.044107] INFO: task find:3695 blocked for more than 120 seconds.
[  721.047879]       Not tainted 3.13.0-32-generic #57-Ubuntu
[  721.051299] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  721.056039] find            D ffff8801efc34440     0  3695   3692 0x00000000
[  721.056044]  ffff8800b72c5be0 0000000000000002 ffff8800eb2b97f0 ffff8800b72c5fd8  [0/596]
[  721.056049]  0000000000014440 0000000000014440 ffff8800eb2b97f0 ffff8801e2806390
[  721.056052]  ffff8801e2806418 ffff8801e2806390 ffff8801e28064c0 ffff8800361d0cf8
[  721.056055] Call Trace:
[  721.056064]  [<ffffffff817200d9>] schedule+0x29/0x70
[  721.056080]  [<ffffffffa0127a55>] wait_for_commit.isra.14+0x45/0x80 [btrfs]
[  721.056086]  [<ffffffff810aaf00>] ? prepare_to_wait_event+0x100/0x100
[  721.056096]  [<ffffffffa0128922>] btrfs_commit_transaction+0x1d2/0x970 [btrfs]
[  721.056104]  [<ffffffffa01117ca>] reserve_metadata_bytes+0x23a/0x8f0 [btrfs]
[  721.056117]  [<ffffffffa0174dc7>] ? btrfs_dequeue_delayed_node+0x77/0x80 [btrfs]
[  721.056126]  [<ffffffffa01123b0>] btrfs_block_rsv_add+0x30/0x60 [btrfs]
[  721.056136]  [<ffffffffa01294f2>] start_transaction+0x432/0x580 [btrfs]
[  721.056146]  [<ffffffffa012965b>] btrfs_start_transaction+0x1b/0x20 [btrfs]
[  721.056160]  [<ffffffffa012e9a8>] btrfs_dirty_inode+0xb8/0xe0 [btrfs]
[  721.056170]  [<ffffffffa012ea34>] btrfs_update_time+0x64/0xd0 [btrfs]
[  721.056175]  [<ffffffff811d7705>] update_time+0x25/0xd0
[  721.056178]  [<ffffffff811d78a9>] touch_atime+0xf9/0x140
[  721.056182]  [<ffffffff811d004f>] iterate_dir+0xbf/0xe0
[  721.056186]  [<ffffffff811d0492>] SyS_getdents+0x92/0x120
[  721.056189]  [<ffffffff811d0150>] ? fillonedir+0xe0/0xe0
[  721.056193]  [<ffffffff8172c81c>] ? tracesys+0x7e/0xe6
[  721.056196]  [<ffffffff8172c87f>] tracesys+0xe1/0xe6