It slowly got worse until my whole system wouldn't start. Finally I ran
btrfs check --repair /dev/sdx1 from a usb boot drive and it said: "cache
and super generation don't match, space cache will be invalidated"

After that it mounted right away. However I will proceed with the newer
kernel as we don't know what caused the corruption in the first place and
why it didn't resolve this automagically.
On Thu, May 14, 2015 at 11:01 AM Alberto Salvia Novella <
<email address hidden>> wrote:

> ** Changed in: linux (Ubuntu)
>    Importance: Medium => High
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1454903
>
> Title:
>   Btrfs Fails to Mount Drive - btrfs-transaction blocked for more than
>   120 seconds.
>
> Status in linux package in Ubuntu:
>   Incomplete
>
> Bug description:
>   Call Trace:
>   kernel:  ffff880408609800 ffff8803e9cba200 ffff8803d06f7398
> ffff8803bc89fe00
>   kernel:  0000000000014200 ffff88040ce9f5c0 ffff880407f9d850
> ffff8803bc89fdd8
>   kernel:  ffff8803bc89fdc8 ffff880407f9d850 0000000000014200
> ffff8803bc89ffd8
>   kernel: btrfs-transacti D ffff8803bc89fdc8     0  4187      2 0x00000000
>   kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this
> message.
>   kernel:       Not tainted 3.19.0-16-generic #16-Ubuntu
>   kernel: INFO: task btrfs-transacti:4187 blocked for more than 120
> seconds.
>   kernel:  [<ffffffff817c934d>] system_call_fastpath+0x16/0x1b
>   kernel:  [<ffffffff812175db>] SyS_mount+0x8b/0xd0
>   kernel:  [<ffffffff812169a4>] do_mount+0x204/0xb20
>   kernel:  [<ffffffff81213b4b>] vfs_kern_mount+0x6b/0x120
>   kernel:  [<ffffffff8119b805>] ? __alloc_percpu+0x15/0x20
>   kernel:  [<ffffffff811f7428>] mount_fs+0x38/0x1c0
>   kernel:  [<ffffffffc0333b00>] btrfs_mount+0x850/0x920 [btrfs]
>   kernel:  [<ffffffffc035db23>] open_ctree+0x1813/0x2090 [btrfs]
>   kernel:  [<ffffffffc039f9c0>] ? replay_one_extent+0x6b0/0x6b0 [btrfs]
>   kernel:  [<ffffffffc03a2214>] btrfs_recover_log_trees+0x1d4/0x470 [btrfs]
>   kernel:  [<ffffffffc039abbb>] walk_log_tree+0xbb/0x1a0 [btrfs]
>   kernel:  [<ffffffffc039a679>] walk_down_log_tree+0x1d9/0x420 [btrfs]
>   kernel:  [<ffffffffc0382f34>] ? alloc_extent_buffer+0x34/0x350 [btrfs]
>   kernel:  [<ffffffffc039b04e>] insert_orphan_item+0x5e/0x90 [btrfs]
>
>   ProblemType: Bug
>   DistroRelease: Ubuntu 15.04
>   Package: linux-image-3.19.0-16-generic 3.19.0-16.16
>   ProcVersionSignature: Ubuntu 3.19.0-16.16-generic 3.19.3
>   Uname: Linux 3.19.0-16-generic x86_64
>   ApportVersion: 2.17.2-0ubuntu1
>   Architecture: amd64
>   AudioDevicesInUse:
>    USER        PID ACCESS COMMAND
>    /dev/snd/controlC0:  jdfalk     3444 F.... pulseaudio
>   Date: Wed May 13 19:03:10 2015
>   HibernationDevice: RESUME=/dev/mapper/sda5_crypt
>   InstallationDate: Installed on 2015-05-10 (4 days ago)
>   InstallationMedia: Ubuntu-Server 15.04 "Vivid Vervet" - Release amd64
> (20150422)
>   MachineType: Gigabyte Technology Co., Ltd. To be filled by O.E.M.
>   ProcEnviron:
>    TERM=xterm-256color
>    PATH=(custom, no user)
>    LANG=en_US.UTF-8
>    SHELL=/bin/bash
>   ProcFB: 0 inteldrmfb
>   ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.19.0-16-generic.efi.signed
> root=UUID=51a981ad-aeb0-4bd7-91c6-2d493155c812 ro rootflags=subvol=@
> crashkernel=384M-:128M
>   PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No
> PulseAudio daemon running, or not running as session daemon.
>   RelatedPackageVersions:
>    linux-restricted-modules-3.19.0-16-generic N/A
>    linux-backports-modules-3.19.0-16-generic  N/A
>    linux-firmware                             1.143
>   RfKill:
>
>   SourcePackage: linux
>   UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
>   UpgradeStatus: No upgrade log present (probably fresh install)
>   dmi.bios.date: 01/06/2014
>   dmi.bios.vendor: American Megatrends Inc.
>   dmi.bios.version: F18i
>   dmi.board.asset.tag: To be filled by O.E.M.
>   dmi.board.name: Z77X-D3H
>   dmi.board.vendor: Gigabyte Technology Co., Ltd.
>   dmi.board.version: x.x
>   dmi.chassis.asset.tag: To Be Filled By O.E.M.
>   dmi.chassis.type: 3
>   dmi.chassis.vendor: Gigabyte Technology Co., Ltd.
>   dmi.chassis.version: To Be Filled By O.E.M.
>   dmi.modalias:
> dmi:bvnAmericanMegatrendsInc.:bvrF18i:bd01/06/2014:svnGigabyteTechnologyCo.,Ltd.:pnTobefilledbyO.E.M.:pvrTobefilledbyO.E.M.:rvnGigabyteTechnologyCo.,Ltd.:rnZ77X-D3H:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvrToBeFilledByO.E.M.:
>   dmi.product.name: To be filled by O.E.M.
>   dmi.product.version: To be filled by O.E.M.
>   dmi.sys.vendor: Gigabyte Technology Co., Ltd.
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1454903/+subscriptions
>