feat(xfs): add Linux 7.0 XFS statistics fields

[dongjiang1989]

ref: https://elixir.bootlin.com/linux/v7.0/source/fs/xfs/xfs_stats.c

Summary

• Update XFS statistics parsing to match the Linux 7.0 kernel (fs/xfs/xfs_stats.c)
• Add support for 9 new btree stat groups: fibt2, rmapbt, refcntbt, rmapbt_mem, rcbagbt, rtrmapbt, rtrmapbt_mem, rtrefcntbt, rtrefcntbt — each with 15
  counters (lookup, compare, insrec, delrec, newroot, killroot, increment, decrement, lshift, rshift, split, join, alloc, free, moves)
• Add 2 new stat groups: zoned (gc_read_calls, gc_bytes) and metafile (inodes, meta)
• Add defer_relog (uint64) and gc xpc (uint64) extended precision counters
• Add trailing comments with proc label names to all Stats struct fields for easier reference
• Update test fixtures (proc and sys) to include all new fields
• Add unit tests for all new stat groups (happy path + invalid count cases)

Test plan

• go vet ./xfs/... passes
• go test ./xfs/... passes (TestParseStats, TestReadProcStat, TestReadSysStats)
• New inline tests cover bad/good cases for: fibt2, rmapbt, refcntbt, rmapbt_mem, rcbagbt, rtrmapbt, rtrmapbt_mem, rtrefcntbt, zoned, metafile, defer_relog, gc xpc

[dongjiang1989]

Hi @SuperQ , PTAL, thanks.

[dongjiang1989]

@discordianfish, @SuperQ Hi, I would appreciate your review of this PR. Thank you.

[stanhu]

@SuperQ Hope you are well. It looks like we received a bug report around this as well in https://gitlab.com/gitlab-org/omnibus-gitlab/-/work_items/9876.

[DragonWork]

@dongjiang1989 I just tested your PR. Thanks!

It does need some further adjustments though, I get this error with Linux 7.0.7:

level=ERROR source=collector.go:168 msg="collector failed" name=xfs duration_seconds=0.000168223 err="failed to retrieve XFS stats: incorrect number of values for zoned stats: 3"

# cat /sys/fs/xfs/stats/stats
extent_alloc 4841 1382197 3198 1341523
abt 0 0 0 0
blk_map 2115317 2567929 18137 12841 12363 5130917 0
bmbt 0 0 0 0
dir 669509 14982 13231 155344
trans 1 184826 0
ig 656660 133557 0 523103 0 269933 8926
log 6444 80186 36 6343 5938
push_ail 187025 0 123178 16362 0 2882 1133 318 0 318
xstrat 4612 0
rw 2516859 5862583
attr 43947 21 23 2446
icluster 0 6036 18228
vnodes 253170 0 0 0 278269 278269 278269 0
buf 2879784 35660 2844127 2677019 2487 35657 10 0 35347
abtb2 13643 138539 706 795 0 0 26 0 26 0 0 0 0 0 502133
abtc2 26954 261791 7513 7602 0 0 42 9 32 4 0 0 0 0 4377106
bmbt2 1139 7786 139 90 0 0 0 0 0 0 0 0 0 0 1307
ibt2 28009 311571 63 42 0 0 0 0 1 0 0 0 0 0 4354
fibt2 41067 163441 8178 8255 0 0 0 0 0 0 0 0 0 0 34399
rmapbt 27442 493733 6653 4919 0 0 1540 1437 1007 1063 22 5 22 5 1032463
refcntbt 17690 177736 1608 1608 0 0 82 13 13 66 1 1 1 1 468361
rmapbt_mem 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
rcbagbt 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
rtrmapbt 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
rtrmapbt_mem 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
rtrefcntbt 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
qm 0 0 0 0 0 0 0 0
zoned 0 0 0
metafile 0
xpc 5113102336 7894530294 22776079333
defer_relog 1
debug 0
gc xpc 0

[DragonWork]

@dongjiang1989 I sent you a PR on your fork to address this.