[gpfsug-discuss] Mass UID/GID change program (uidremap)

[Jonathan Buzzard]

My university has been giving me Fridays off during lock down so I
I have spent a bit of time and added modification of Posix ACL's through 
the standard library and tidied up the code a bit. Much of it is based 
on preexisting code which did speed things up.

The error checking is still rather basic, and there had better be no 
errors in the mapping file. I have some ideas on how to extend it to do 
ACL's either through libacl or the GPFS API at compile time that I will 
probably look at on Friday. There is however the issue of incomplete 
documentation on the gpfs_acl_t structure. It will also be a lot slower 
if only a subset of the files have an ACL because you are going to need 
to attempt to get the ACL on every file.

It uses the standard C library call nftw so can be pointed at a 
directory rather than a whole file system, which in the absence of a 
test GPFS file system that I could wreck would make testing difficult. 
Besides which the GPFS inode scan is lacking in features to make it 
suitable for this sort of application IMHO.

There is a test directory in the tarball that is mostly full of a 
version of the Linux source code where all the files have been truncated 
to zero bytes. There is also some files for symlink, and access/default 
ACL testing. Targets exist in the Makefile to setup the testing 
directory correctly and run the test. There is no automated testing that 
it works correctly however.

I have also included a script to generate a mapping file for all the 
users on the local system to AD ones based on the idmap_rid algorithm. 
Though in retrospect calling mmrepquota to find all the users and groups 
on the file system might have been a better idea.

It's all under GPL v3 and can be downloaded at

    http://www.buzzard.me.uk/jonathan/downloads/uidremap-0.2.tar.gz

Yeah I should probably use GitHub, but I am old school. Anyway take a 
look, the C code is very readable and if you take out the comments at 
the top only 300 lines.


JAB.

-- 
Jonathan A. Buzzard                         Tel: +44141-5483420
HPC System Administrator, ARCHIE-WeSt.
University of Strathclyde, John Anderson Building, Glasgow. G4 0NG