[LU-19590] Supp gid fix for cross-MDT operations where parent/child on diff MDTs w/ different groups

• Type: Bug
• Resolution: Fixed
• Priority: Medium
• Fix Version/s: Lustre 2.17.0
• Affects Version/s: Lustre 2.17.0
• Severity: 3
• Assignee: Kaitlin Hoang
• Reporter: Kaitlin Hoang

Description

For cross-MDT open where parent and child are on different MDTs and owned by different supplementary groups, we should hint client via similar mechanism as in https://review.whamcloud.com/c/fs/lustre-release/+/56098

Right now, for cross-MDT open, mdt_reint_open calls mdt_cross_open which skips the logic later to check for EACESS and hint client. The client will try and guess the child dir or file's permissions w/ the parent's permissions - if they do not match, client will get an incorrect EACESS. We can fix this by adding a check for EACESS into mdt_cross_open.

Modified existing sanity-sec 83 to fail w/o this change

== sanity-sec test 83: Suppgids for cross-MDT ops ======== 22:00:18 (1762898418)
mdt.lustre-MDT0000.identity_upcall=NONE
mdt.lustre-MDT0001.identity_upcall=NONE
172.31.73.235@tcp:/lustre /mnt/lustre lustre rw,seclabel,checksum,encrypt,flock,lazystatfs,lruresize,nolock,statfs_project,nouser_fid2path,user_xattr,verbose 0 0
Stopping client ip-172-31-73-235.ec2.internal /mnt/lustre (opts:)
Starting client: ip-172-31-73-235.ec2.internal:  -o user_xattr,flock 172.31.73.235@tcp:/lustre /mnt/lustre
ls: cannot access '/mnt/lustre/d83.sanity-sec/subdir/*': No such file or directory
 sanity-sec test_83: @@@@@@ FAIL: ls /mnt/lustre/d83.sanity-sec/subdir/* as sanityusr failed 
  Trace dump:
  = /home/ec2-user/lustre-release/lustre/tests/test-framework.sh:7314:error()
  = /home/ec2-user/lustre-release/lustre/tests/sanity-sec.sh:10605:test_83()
  = /home/ec2-user/lustre-release/lustre/tests/test-framework.sh:7690:run_one()
  = /home/ec2-user/lustre-release/lustre/tests/test-framework.sh:7753:run_one_logged()
  = /home/ec2-user/lustre-release/lustre/tests/test-framework.sh:7553:run_test()
  = /home/ec2-user/lustre-release/lustre/tests/sanity-sec.sh:10607:main()
Dumping lctl log to /tmp/test_logs/2025-11-11/215920/sanity-sec.test_83.*.1762898419.log
Dumping logs only on local client.
Removing user sanityusr from group grptest832
Removing user sanityusr from group grptest83
FAIL 83 (1s)

Issue Links

• is related to: LU-19462 Send suppgids from client for cross-MDT operations