[Bug 1509654] Re: BTRFS is completly unusable on 15.10

[Alexander Fougner]

Hi,

Is it possible that you've set the default subvolume to something else
than the actual filesystem root? You can check this by doing the
following.

$ sudo btrfs subvol get-default <mountpoint>

Also, after you try to mount the root in /mnt, could you please post the
output of the relevant parts of /proc/mounts ?

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Title:
  BTRFS is completly unusable on 15.10

Status in btrfs-tools package in Ubuntu:
  New

Bug description:
  btrfs can see subvolumes but can't manipulate them. For example I can
  list subvolumes:

  sudo btrsfs subvol list /
  ID 385 gen 77889 top level 5 path @
  ID 416 gen 77410 top level 5 path @apt-snapshot-release-upgrade-wily-2015-10-23_23:25:25
  ID 417 gen 77742 top level 5 path @apt-snapshot-2015-10-23_23:25:26
  ID 418 gen 77412 top level 417 path @apt-snapshot-2015-10-23_23:25:26/@
  ID 419 gen 77413 top level 5 path @apt-snapshot-2015-10-23_23:25:27

  But I cant delete them:

  sudo btrfs subvol delete /@apt-snapshot-release-upgrade-wily-2015-10-23_23:25:25
  ERROR: error accessing '/@apt-snapshot-release-upgrade-wily-2015-10-23_23:25:25'

  Even if I mount rootfs in another mountpoint:

  sudo mount /dev/mapper/system-root /mnt/
  sudo btrfs subvol delete /mnt/@apt-snapshot-release-upgrade-wily-2015-10-23_23:25:25
  ERROR: error accessing '/mnt/@apt-snapshot-release-upgrade-wily-2015-10-23_23:25:25'

  I can't see subvolumes in root directory, I see files in subvolumes.

  ls /mnt/
  bin   dev   initrd.img      lib32  mnt   root  srv  usr      vmlinuz.old
  boot  etc   initrd.img.old  lib64  opt   run   sys  var
  core  home  lib

  When I'm boot live Ubuntu 15.04 from CD I can manipulate subvolumes
  with no problems.

  ProblemType: Bug
  DistroRelease: Ubuntu 15.10
  Package: btrfs-tools 4.0-2
  ProcVersionSignature: Ubuntu 4.2.0-17.20-lowlatency 4.2.3
  Uname: Linux 4.2.0-17-lowlatency x86_64
  ApportVersion: 2.19.1-0ubuntu3
  Architecture: amd64
  Date: Sat Oct 24 14:25:58 2015
  InstallationDate: Installed on 2015-02-13 (252 days ago)
  InstallationMedia: Ubuntu 14.10 "Utopic Unicorn" - Release amd64 (20141022.1)
  SourcePackage: btrfs-tools
  UpgradeStatus: Upgraded to wily on 2015-10-23 (0 days ago)

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