[LU-13335] add name lookup for project IDs

• Type: Improvement
• Resolution: Unresolved
• Priority: Minor
• Labels: lug23dd lug24dd medium patch utils
• Assignee: Fred Dilger
• Reporter: Andreas Dilger

Description

It would be useful to allow names to be mapped to projid numbers using the /etc/projid file (projid.5), as is used by the XFS quota utility (xfs_quota.8):

usera:1
userc:3

There should be a new function struct ll_project *llapi_getprjname(const char *name) function that is called by lfs and lctl to read the /etc/projid file and lookup the name and return the projid, while struct ll_project *llapi_getprjid(__u32 prjid) would lookup the numeric project ID and return the name:

struct ll_project {
        __u32 lp_projid;
        char *lp_name;
};

Returning the struct instead of a single value (name or prjid) allows expanding this interface in the future (e.g. to list which users are allowed to use/change the group, passwords for the group, etc. as with getgrnam(), getgrgid(), getpwnam(), getpwuid()).

It isn't very clear what benefit the /etc/projects file (projects.5) provides, so I'm not yet sure whether we need to implement support for this or not.

This should be available for use by lfs project -p, lfs find -projid, lfs quota -p, lfs setquota -p.

Issue Links

• has to be done before: LU-18659 add new 'lfs projectadd' command to add project entries to the /etc/projid file
• has to be done before: LU-18638 print project name with 'lfs project'
• has to be done before: LU-18640 add option for 'lfs project' to do project name and id lookup only
• is related to: LU-14915 Add project flags to manage the project's directories and files
• is related to: LU-14968 add password for project files
• is related to: LU-17702 'lfs quota -u $USER' should print quota for all Lustre mountpoints
• is related to: LU-12056 tar doesn't support project id
• is related to: LU-18661 allow enable/disable projname->username fallback