Enhancements to support filesystems created with bigtime and inobtcount

SUSE Linux Enterprise Server 12 SP5

Some imported xfs filesystems could not be mounted on SUSE Linux Enterprise 12 Service Pack 5. 

Code updates were made to the kernel, grub2 and related programs, in order to allow imported xfs filesystems created with the 'bigtime' and 'inobtcount' attributes to be mounted in read-only mode.

Any SLES12 SP5 server that is upgraded to include kernel 4.12.14-122.139.1 or later, will also need to have grub2 updated (to at least 2.02-146.1 or later). Failure to update grub at the same time as updating the kernel, may lead to a boot issue, if the server that is being updated boots from an xfs filesystem.

Later versions of xfs (5.13.x) provide for the creation of filesystems with additional functionality and attributes. The filesystems that could not be mounted, had been created with attribute support that is not present in the xfs versions used in SLES12 SP5 (xfs 4.15.x) and no kernel or grub2 support for these enhancements existed in SLES12 SP5.

The support for bigtime and inobtcount was provided by code updates to the kernel, grub and related programs. It was not necessary to modify the xfsprogs code, as the enhancements made are intended only to allow the read-only mounting of xfs filesystems that were created 'elsewhere' using later versions of xfs.

The enhancements first appear in kernel version 4.12.14-122.139.1 and grub2 version 2.02-146.1

Note that the enhancements made do not include any additional support for the reflink attribute, which will remain 'experimental'. There is also no facility added to allow the creation of xfs filesystems with attribute support for bigtime and inobtcount.

The default attribute support for filesystems created with xfs 5.13 and later, includes bigtime, inobtcount and reflink, hence the need to mount these filesystems as read-only on SLES12 SP5. Enabling the experimental support for reflink and mounting these imported filesystems as read-write is done at-your-own-risk and is not supported.

Note that xfs utilities in SLES12 SP5 have not been updated to report information on filesystems using bigtime and inobtcount. This means that output from these utilities will not indicate the presence of these attributes.