[LU-18834] Lustre can return negative stats value

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.17.0
• Severity: 3
• Assignee: Emoly Liu
• Reporter: Raphael Druon

Description

Looking at stats from obdfilter:

obdfilter.testfs-OST0000.stats=
snapshot_time             1742378286.332900343 secs.nsecs
start_time                1742228736.573307453 secs.nsecs
elapsed_time              149549.759592890 secs.nsecs
read_bytes                3469178 samples [bytes] 1048576 1048576 3637696790528 3814401549824688128
write_bytes               186442470 samples [bytes] 1001 16777216 3092142771667945 4612433686335277585
read                      3469178 samples [usecs] 623 16467 15904108552 85258323792650
write                     186442470 samples [usecs] 36 149845092510 -823495890607571055 4426400394686790401
punch                     562 samples [usecs] 10 48020 5760464 159896287662
sync                      719 samples [usecs] 0 76522 930977 13284701619
create                    11 samples [usecs] 2 30809 69396 1415757344
statfs                    58418 samples [usecs] 0 756 191916 2548952
get_info                  2 samples [usecs] 294 2488 2782 6276580
set_info                  48 samples [usecs] 5 15 562 6948

The following stat reports a negative value:

write                     186442470 samples [usecs] 36 149845092510 -823495890607571055 4426400394686790401

I suspect that's an overflow issue since negative value is not expected here.