kernel-packages team mailing list archive

[Andy Whitcroft <apw@xxxxxxxxxxxxx>]

** Summary changed:

- Request for updated Ubuntu virtual kernel images
+ XFS log handling issue (with patch) -- (was Request for updated Ubuntu virtual kernel images)

** Changed in: linux (Ubuntu)
   Importance: Undecided => Medium

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https://bugs.launchpad.net/bugs/1241848

Title:
  XFS log handling issue (with patch) -- (was Request for updated Ubuntu
  virtual kernel images)

Status in “linux” package in Ubuntu:
  Confirmed

Bug description:
  I have a Ubuntu 12.04 virtual machine with a 400 GB volume attached to
  it. This volume uses XFS filesystem on top of LVM2 setup and the
  backup system we use takes hourly backups. Since we freeze and
  unfreeze the filesystem during backups, I started seeing the following
  in the logs a lot.

  Oct 14 06:52:35 localhost kernel: [4269962.940638] XFS (dm-1): xlog_space_left: head behind tail
  Oct 14 06:52:35 localhost kernel: [4269962.940639]   tail_cycle = 7, tail_bytes = 38953984
  Oct 14 06:52:35 localhost kernel: [4269962.940640]   GH   cycle = 7, GH   bytes = 38953976
  Oct 14 06:52:35 localhost kernel: [4269962.940656] XFS (dm-1): xlog_space_left: head behind tail
  Oct 14 06:52:35 localhost kernel: [4269962.940657]   tail_cycle = 7, tail_bytes = 38953984
  Oct 14 06:52:35 localhost kernel: [4269962.940657]   GH   cycle = 7, GH   bytes = 38953976

  This started occurred a lot and the backups were working fine for a
  day and then they started failing because they failed to remove the
  LVM snapshot using `lvremove`. After a little bit of research I found
  this commit in the linux kernel:
  https://github.com/torvalds/linux/commit/3948659e30808fbaa7673bbe89de2ae9769e20a7
  which seems to fix the exact same problem I'm having.

  This commit fixes this issue form kernel version 3.4 onwards. The most
  recent virtual kernel available for Ubuntu 12.04 LTS release is
  "3.2.0-49-virtual". So the possible solutions are to either backport
  the xfs fix to 3.2.x kernel or release virtual kernel releases for the
  latest version of the kernel.

  I'll be happy to provide more information regarding this issue.

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