Comment 7 for bug 1212679

Found also previous btrfs call traces in kern.log, e.g. with kernel 3.10.0-6:

Aug 3 21:33:37 server kernel: [44521.116044] INFO: task btrfs-transacti:1603 blocked for more than 120 seconds.
Aug 3 21:33:37 server kernel: [44521.116055] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Aug 3 21:33:37 server kernel: [44521.116060] btrfs-transacti D 00000000 0 1603 2 0x00000000
Aug 3 21:33:37 server kernel: [44521.116071] efedbe6c 00000046 00018000 00000000 d24c73e0 f593b070 efedbe48 c1a2c580
Aug 3 21:33:37 server kernel: [44521.116085] c18c91a0 00000000 c1a2c580 f7bbc580 f15ca6a0 fb1b53f8 f50dd140 00000000
Aug 3 21:33:37 server kernel: [44521.116098] f5162400 0014cbf3 00000000 f50dd000 00018000 d24c73e0 efedbe48 fb1ea1fe
Aug 3 21:33:37 server kernel: [44521.116111] Call Trace:
Aug 3 21:33:37 server kernel: [44521.116202] [<fb1b53f8>] ? release_extent_buffer+0x58/0xb0 [btrfs]
Aug 3 21:33:37 server kernel: [44521.116256] [<fb1ea1fe>] ? btrfs_release_delayed_inode.part.16+0x2e/0x40 [btrfs]
Aug 3 21:33:37 server kernel: [44521.116293] [<fb172ceb>] ? btrfs_put_tree_mod_seq+0x11b/0x150 [btrfs]
Aug 3 21:33:37 server kernel: [44521.116305] [<c1622203>] schedule+0x23/0x60
Aug 3 21:33:37 server kernel: [44521.116313] [<c1620a85>] schedule_timeout+0x1a5/0x250
Aug 3 21:33:37 server kernel: [44521.116321] [<c16237cd>] ? _raw_spin_lock+0xd/0x10
Aug 3 21:33:37 server kernel: [44521.116368] [<fb1b340f>] ? btrfs_run_ordered_operations+0x19f/0x220 [btrfs]
Aug 3 21:33:37 server kernel: [44521.116380] [<c1039b28>] ? default_spin_lock_flags+0x8/0x10
Aug 3 21:33:37 server kernel: [44521.116388] [<c1068d28>] ? prepare_to_wait+0x48/0x70
Aug 3 21:33:37 server kernel: [44521.116431] [<fb1987fc>] btrfs_commit_transaction+0x1dc/0xc80 [btrfs]
Aug 3 21:33:37 server kernel: [44521.116440] [<c1068ee0>] ? wake_up_bit+0x20/0x20
Aug 3 21:33:37 server kernel: [44521.116481] [<fb192c5d>] transaction_kthread+0x16d/0x200 [btrfs]
Aug 3 21:33:37 server kernel: [44521.116522] [<fb192af0>] ? btrfs_cleanup_transaction+0x4b0/0x4b0 [btrfs]
Aug 3 21:33:37 server kernel: [44521.116529] [<c1068454>] kthread+0x94/0xa0
Aug 3 21:33:37 server kernel: [44521.116537] [<c1070000>] ? smpboot_register_percpu_thread+0x50/0xc0
Aug 3 21:33:37 server kernel: [44521.116546] [<c162aa77>] ret_from_kernel_thread+0x1b/0x28
Aug 3 21:33:37 server kernel: [44521.116553] [<c10683c0>] ? kthread_create_on_node+0xc0/0xc0