[LU-10285] Make sure that FLR is able to extend a plain file on older file system

• Type: Technical task
• Resolution: Done
• Priority: Blocker
• Affects Version/s: Lustre 2.11.0
• Labels: FLR
• Assignee: Sarah Liu
• Reporter: Jinshan Xiong (Inactive)

Description

Now lfs mirror extend should be able to extend a plain file to mirrored file by using command like:

lfs mirror extend -N2 -E 1M -E eof -c 2 file

while 'file' is a file with plain layout. This has already been verified in FLR branch, please check the test case sanity-flr:test_0d().

We also need to verify this command works on an older file system. For example, a file system is formatted in 2.10, and then create regular files with plain and PFL layout in it, and then upgrade Lustre to 2.11, and then use the above command to convert plain files to mirrored, which should work fine.