Unable to mount or check XFS filesystem

Issue

• A XFS filesystem hangs and running xfs_repair -nv /dev/sda1 the following error is returned:

  # xfs_repair -n /dev/sda1
  ERROR: The filesystem has valuable metadata changes in a log which needs to
  be replayed. Mount the filesystem to replay the log, and unmount it before
  re-running xfs_check. If you are unable to mount the filesystem, then use
  the xfs_repair -L option to destroy the log and attempt a repair.
  Note that destroying the log may cause corruption -- please attempt a mount
  of the filesystem before doing this.
  

  NOTE: Older xfsprogs releases used to ship the xfs_check tool, however it was very slow and did not scale well for large filesystems. As such, it has been deprecated in favor of xfs_repair -n.

• In the above scenario, the filesystem would also not mount:

  # mount /dev/sda1 /mountpoint/
  mount: Structure needs cleaning
  

• The last resort is running xfs_repair -L, which will clean the entries in the transaction log journal and ultimately allow the filesystem to be mounted.

  kernel: XFS internal error XFS_WANT_CORRUPTED_GOTO at line 1572 of file fs/xfs/xfs_alloc.c.  Caller 
  0xffffffff88871969
  kernel: 
  kernel: Call Trace:
  kernel:  [<ffffffff8886fe2f>] :xfs:xfs_free_ag_extent+0x19e/0x67e
  kernel:  [<ffffffff88871969>] :xfs:xfs_free_extent+0xa9/0xc9
  kernel:  [<ffffffff8887a755>] :xfs:xfs_bmap_finish+0xee/0x15f
  kernel:  [<ffffffff88899927>] :xfs:xfs_itruncate_finish+0x185/0x2af
  kernel:  [<ffffffff888b1001>] :xfs:xfs_inactive+0x1de/0x40f
  kernel:  [<ffffffff888bb8c1>] :xfs:xfs_fs_clear_inode+0xa4/0xeb
  kernel:  [<ffffffff80022eee>] clear_inode+0xd2/0x123
  kernel:  [<ffffffff8002f3ec>] generic_delete_inode+0xde/0x143
  kernel:  [<ffffffff8003c716>] do_unlinkat+0xd5/0x141
  kernel:  [<ffffffff8005d229>] tracesys+0x71/0xe0
  kernel:  [<ffffffff8005d28d>] tracesys+0xd5/0xe0
  kernel: 
  kernel: xfs_force_shutdown(sda1,0x8) called from line 4269 of file fs/xfs/xfs_bmap.c.  Return address = 
  0xffffffff8887a78a
  kernel: Filesystem "sda1": Corruption of in-memory data detected.  Shutting down filesystem: sdm1
  kernel: Please umount the filesystem, and rectify the problem(s)
  kernel: nfsd: non-standard errno: 5