xfs v5

[Elan Ruusamäe]

can we go back to v4 or at least detect running kernel  first?


    XFS Version v5 superblock VS old kernels ( < v3.15) issues

Using recent Th provided xfsprogs|mkfs.xfs|results in created filesystem 
with v5 superblock which is not fully supported in 3.14 and lower 
kernels. Below message is produced in kernel log while trying to mount 
such filesystem on old kernel (3.14):

[3180866.360834] XFS (dm-13): Version 5 superblock detected. This kernel has EXPERIMENTAL support enabled!
                  Use of these features in this kernel is at your own risk!
[3180866.360848] XFS (dm-13): Superblock has unknown read-only compatible features (0x1) enabled.
[3180866.360853] XFS (dm-13): Attempted to mount read-only compatible filesystem read-write.
                  Filesystem can only be safely mounted read only.
[3180866.360868] XFS (dm-13): SB validate failed with error 22.

To overcome it and create v4 superblock, one need to provide 
specific|mkfs.xfs|options to disable v5 features:

mkfs.xfs -m crc=0,finobt=0 /dev/sys/apus-vserver

See related issue 
discussion:http://oss.sgi.com/archives/xfs/2015-08/msg00548.html





-- 
glen