BUG - XFS Reflink support not detected in Linux 5.10 kernel

[dandav]

If you try and use XFS reflinks with the repository installed on a 5.10 Linux kernel VBR fails to detect the reflink support and returns the following error:

"File system behind the provided path has XFS reflinks diabled: /mnt/veeamrepo/backups Proceed anyway?"

On the Linux repository reflinks is enabled and I have tested it is working correctly using manuall file copies. In the VeeamTransportSvg.log it shows the below output which clearly shows from the xfs_info command reflinks is enabled on the filesystem. The only difference in the xfs_info output between kernels 5.4 and 5.10 is that the "bigtime = 0" variable doesn't exist in 5.4 so it appears as if this might have broken the code parsing the xfs_info output string.

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[24.08.2021 09:23:22.692] <139625863198464> cli      | Method [FileSystem.GetXfsRefLinkSupport] completed. Elapsed time: [00:00:00.023]
[24.08.2021 09:23:22.692] <139625863198464> cli      | - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
[24.08.2021 09:23:22.692] <139625863198464> cli      | Result
[24.08.2021 09:23:22.692] <139625863198464> cli      |   (EString) Answer = meta-data=/dev/sdb1              isize=512    agcount=30, agsize=268435455 blks
[24.08.2021 09:23:22.692] <139625863198464> cli      |          =                       sectsz=4096  attr=2, projid32bit=1
[24.08.2021 09:23:22.692] <139625863198464> cli      |          =                       crc=1        finobt=1, sparse=1, rmapbt=0
[24.08.2021 09:23:22.692] <139625863198464> cli      |          =                       reflink=1    bigtime=0
[24.08.2021 09:23:22.692] <139625863198464> cli      | data     =                       bsize=4096   blocks=8053063168, imaxpct=5
[24.08.2021 09:23:22.692] <139625863198464> cli      |          =                       sunit=0      swidth=0 blks
[24.08.2021 09:23:22.692] <139625863198464> cli      | naming   =version 2              bsize=4096   ascii-ci=0, ftype=1
[24.08.2021 09:23:22.692] <139625863198464> cli      | log      =internal log           bsize=4096   blocks=521728, version=2
[24.08.2021 09:23:22.692] <139625863198464> cli      |          =                       sectsz=4096  sunit=1 blks, lazy-count=1
[24.08.2021 09:23:22.692] <139625863198464> cli      | realtime =none                   extsz=4096   blocks=0, rtextents=0
[24.08.2021 09:23:22.692] <139625863198464> cli      |
[24.08.2021 09:23:22.692] <139625863198464> cli      |   (EString) Command = xfs_info /mnt/veeamrepo
[24.08.2021 09:23:22.692] <139625863198464> cli      |   (EInt32) ExitCode = 0
[24.08.2021 09:23:22.692] <139625863198464> cli      |   (EString) StdError = <empty>
[24.08.2021 09:23:22.692] <139625863198464> cli      | -------------------------------------------------------------------------------

[HannesK]

Hello,
it's working fine with kernel 5.10 for me.

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root@kerneltest:~# uname -a
Linux kerneltest 5.10.59-051059-generic #202108151334 SMP Sun Aug 15 14:16:01 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

do you have a Veeam support case number and more details about which distribution you are using?

Best regards,
Hannes

[dandav]

No, I hadn't logged a job as it wasn't a production issue, just playing in my lab.

Distribution is Debian 11.

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lhc@drrepo:/var/log/VeeamBackup$ uname -a
Linux drrepo 5.10.0-8-amd64 #1 SMP Debian 5.10.46-4 (2021-08-03) x86_64 GNU/Linux

[dandav]

Here's the comparison with our production Linux repository running Ubuntu 20.04. As you can see the xfs_info output is formatted identically except for the new bigtime variable on the same line as reflinks. Bigtime should show up in 5.10 kernels onwards as they now support 64-bit timestamps to fix the 2038 problem with 32 bit timestamps.

uname output:

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Linux veeamhl 5.4.0-81-generic #91-Ubuntu SMP Thu Jul 15 19:09:17 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

VeeamTransportSvc.log output:

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[24.08.2021 16:36:30.616] <140665899947776> cli      | Method [FileSystem.GetXfsRefLinkSupport] comp                                                leted. Elapsed time: [00:00:00.019]
[24.08.2021 16:36:30.616] <140665899947776> cli      | - - - - - - - - - - - - - - - - - - - - - - -                                                 - - - - - - - - - - - - - - - - -
[24.08.2021 16:36:30.616] <140665899947776> cli      | Result
[24.08.2021 16:36:30.616] <140665899947776> cli      |   (EString) Answer = meta-data=/dev/bcache0p1                                                         isize=512    agcount=32, agsize=122090240 blks
[24.08.2021 16:36:30.616] <140665899947776> cli      |          =                       sectsz=4096                                                  attr=2, projid32bit=1
[24.08.2021 16:36:30.616] <140665899947776> cli      |          =                       crc=1                                                        finobt=1, sparse=1, rmapbt=0
[24.08.2021 16:36:30.616] <140665899947776> cli      |          =                       reflink=1
[24.08.2021 16:36:30.616] <140665899947776> cli      | data     =                       bsize=4096                                                   blocks=3906885120, imaxpct=5
[24.08.2021 16:36:30.616] <140665899947776> cli      |          =                       sunit=128                                                    swidth=512 blks
[24.08.2021 16:36:30.616] <140665899947776> cli      | naming   =version 2              bsize=4096                                                   ascii-ci=0, ftype=1
[24.08.2021 16:36:30.616] <140665899947776> cli      | log      =internal log           bsize=4096                                                   blocks=521728, version=2
[24.08.2021 16:36:30.616] <140665899947776> cli      |          =                       sectsz=4096                                                  sunit=1 blks, lazy-count=1
[24.08.2021 16:36:30.616] <140665899947776> cli      | realtime =none                   extsz=4096                                                   blocks=0, rtextents=0
[24.08.2021 16:36:30.616] <140665899947776> cli      |
[24.08.2021 16:36:30.616] <140665899947776> cli      |   (EString) Command = xfs_info /mnt/veeamrepo                                                1
[24.08.2021 16:36:30.616] <140665899947776> cli      |   (EInt32) ExitCode = 0
[24.08.2021 16:36:30.616] <140665899947776> cli      |   (EString) StdError = <empty>
[24.08.2021 16:36:30.616] <140665899947776> cli      | ---------------------------------------------                                                ----------------------------------

[HannesK]

my test was with Ubuntu 20.04 and kernel 5.10 and it worked fine.

Thanks for mentioning that you use Debian 11. I see the same issue. As for now only Debian 10 is fully supported. So I'm pretty sure that QA will catch that issue before declaring full support for Debian 11. I will talk to them whether they already have it on their agenda.

UPDATE: planned to be supported in 11a (#312552)

[dandav]

Excellent, thanks Hannes