generic/645 failing on ext4, xfs (probably others) on all LTS kernels

["Theodore Ts'o" <tytso@mit.edu>]

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The test generic/645 is failing on (at least) 6.6, 6.1, 5.15 LTS
kernels.

This fix is apparently commit dacfd001eaf2 ("fs/mnt_idmapping.c:
Return -EINVAL when no map is written"), but in order to take this
patch, it looks like we need to backport the 4 patch series
"mnt_idmapping: decouple from namespaces"[1] (and possibly others; I
haven't tried yet).

[1] https://lore.kernel.org/all/20231122-vfs-mnt_idmap-v1-0-dae4abdde5bd@kernel.org/

This looks fairly involved so the questions I have are:

(1) Should we request this patch series plus commit dacfd001eaf2 into
the stable kernels --- or should I just add a versioned excludes[2]
and just skip generic/645 from all kernels older than Linux 6.9 if we
think it's too involved and/or risky to backport these id mapping
changes?

(2) How much do we care that generic/645 is failing on LTS kernels?
Are user/applications going to notice or care?

Thanks,

					- Ted

[2] Like this:

diff --git a/test-appliance/files/root/fs/global_exclude b/test-appliance/files/root/fs/global_exclude
index d7acf89f..42902152 100644
--- a/test-appliance/files/root/fs/global_exclude
+++ b/test-appliance/files/root/fs/global_exclude
@@ -30,6 +30,14 @@ generic/484
 generic/554
 #endif
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(6,9,0)
+// This test failure is fixed by commit dacfd001eaf2
+// ("fs/mnt_idmapping.c: Return -EINVAL when no map is written"),
+// but it's too involved to backport it and its dependencies to
+// the LTS kernels.
+generic/645
+#endif
+
 #ifndef IS_DAX_CONFIG
 // Unless we are testing the dax config, we can exclude all dax tests
 -g dax

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From: Xfstests Reporter <tytso@thunk.org>
To: theodore.tso@gmail.com
Subject: xfstests results ltm-20241016165408-0014 6.6.61-rc1-xfstests-g4744f45e99fb-8
Date: Sun, 10 Nov 2024 15:12:05 +0000 (UTC)
Message-ID: <kF4Z6m8lS4qxluY2wPzMCA@geopod-ismtpd-6>

TESTRUNID: ltm-20241016165408-0014
KERNEL:    kernel 6.6.61-rc1-xfstests-g4744f45e99fb #8 SMP PREEMPT_DYNAMIC Sun Nov 10 05:14:53 EST 2024 x86_64
CMDLINE:   -c ext4/all,xfs/all -g auto --repo stable-rc.git --watch linux-6.6.y
CPUS:      2
MEM:       7680

ext4/4k: 576 tests, 2 failures, 55 skipped, 6031 seconds
  Failures: generic/365 generic/645
ext4/1k: 570 tests, 3 failures, 59 skipped, 5818 seconds
  Failures: generic/627 generic/645 generic/750
ext4/ext3: 568 tests, 2 failures, 148 skipped, 4243 seconds
  Failures: generic/365 generic/645
ext4/encrypt: 551 tests, 2 failures, 171 skipped, 4186 seconds
  Failures: generic/365 generic/645
ext4/nojournal: 568 tests, 2 failures, 126 skipped, 4458 seconds
  Failures: generic/365 generic/645
ext4/ext3conv: 573 tests, 3 failures, 57 skipped, 6299 seconds
  Failures: generic/347 generic/365 generic/645
ext4/adv: 569 tests, 2 failures, 63 skipped, 4802 seconds
  Failures: generic/365 generic/645
ext4/dioread_nolock: 574 tests, 2 failures, 55 skipped, 4746 seconds
  Failures: generic/365 generic/645
ext4/data_journal: 569 tests, 2 failures, 132 skipped, 4243 seconds
  Failures: generic/365 generic/645
ext4/bigalloc_4k: 547 tests, 2 failures, 58 skipped, 4770 seconds
  Failures: generic/365 generic/645
ext4/bigalloc_1k: 548 tests, 1 failures, 69 skipped, 4855 seconds
  Failures: generic/645
ext4/dax: 562 tests, 2 failures, 159 skipped, 2977 seconds
  Failures: generic/365 generic/645
xfs/4k: 1157 tests, 13 failures, 181 skipped, 11983 seconds
  Failures: generic/091 generic/127 generic/263 generic/363 generic/365 
    generic/616 generic/645 xfs/629 xfs/630 xfs/631 xfs/632 xfs/806
  Flaky: generic/455: 20% (1/5)
xfs/1k: 1157 tests, 12 failures, 169 skipped, 12621 seconds
  Failures: generic/091 generic/127 generic/263 generic/363 generic/616 
    generic/645 xfs/629 xfs/630 xfs/631 xfs/632 xfs/806
  Flaky: generic/560: 20% (1/5)
xfs/v4: 1156 tests, 11 failures, 476 skipped, 8452 seconds
  Failures: generic/363 generic/365 generic/645 xfs/348 xfs/629 xfs/630 
    xfs/631 xfs/632 xfs/803 xfs/804 xfs/806
xfs/adv: 1157 tests, 13 failures, 167 skipped, 11341 seconds
  Failures: generic/091 generic/127 generic/263 generic/363 generic/365 
    generic/616 generic/645 xfs/157 xfs/629 xfs/630 xfs/631 xfs/632 
    xfs/806
xfs/quota: 1157 tests, 12 failures, 166 skipped, 12417 seconds
  Failures: generic/091 generic/127 generic/263 generic/363 generic/365 
    generic/616 generic/645 xfs/629 xfs/630 xfs/631 xfs/632 xfs/806
xfs/quota_1k: 1157 tests, 13 failures, 169 skipped, 14282 seconds
  Failures: generic/091 generic/127 generic/263 generic/363 generic/627 
    generic/645 xfs/629 xfs/630 xfs/631 xfs/632 xfs/806
  Flaky: generic/112: 20% (1/5)   generic/616: 80% (4/5)
xfs/dirblock_8k: 1157 tests, 13 failures, 166 skipped, 12183 seconds
  Failures: generic/091 generic/127 generic/263 generic/363 generic/365 
    generic/616 generic/645 xfs/629 xfs/630 xfs/631 xfs/632 xfs/806
  Flaky: generic/075: 80% (4/5)
xfs/realtime: 1156 tests, 6 failures, 521 skipped, 9530 seconds
  Failures: generic/363 generic/365 generic/455 generic/645 xfs/629 xfs/806
xfs/realtime_28k_logdev: 1156 tests, 5 failures, 602 skipped, 16344 seconds
  Failures: generic/363 generic/365 generic/645 xfs/598 xfs/806
xfs/realtime_logdev: 1156 tests, 7 failures, 575 skipped, 12594 seconds
  Failures: generic/363 generic/365 generic/645 xfs/598 xfs/629 xfs/789 
    xfs/806
xfs/logdev: 1157 tests, 14 failures, 236 skipped, 15071 seconds
  Failures: generic/091 generic/127 generic/263 generic/363 generic/365 
    generic/616 generic/645 xfs/598 xfs/629 xfs/630 xfs/631 xfs/632 
    xfs/806
  Flaky: generic/112: 60% (3/5)
xfs/dax: 1167 tests, 7 failures, 552 skipped, 5763 seconds
  Failures: generic/365 generic/645 xfs/629 xfs/630 xfs/631 xfs/632 xfs/806
Totals: 21269 tests, 5132 skipped, 739 failures, 0 errors, 186798s

FSTESTIMG: gce-xfstests/xfstests-amd64-202410151341
FSTESTPRJ: gce-xfstests
FSTESTVER: blktests f043065 (Thu, 20 Jun 2024 16:26:22 +0900)
FSTESTVER: fio  fio-3.38 (Wed, 2 Oct 2024 12:53:13 -0600)
FSTESTVER: fsverity v1.6 (Wed, 20 Mar 2024 21:21:46 -0700)
FSTESTVER: ima-evm-utils v1.5 (Mon, 6 Mar 2023 07:40:07 -0500)
FSTESTVER: libaio   libaio-0.3.108-82-gb8eadc9 (Thu, 2 Jun 2022 13:33:11 +0200)
FSTESTVER: ltp  20240930 (Mon, 30 Sep 2024 12:27:12 +0200)
FSTESTVER: quota  v4.05-69-g68952f1 (Mon, 7 Oct 2024 15:45:56 -0400)
FSTESTVER: util-linux v2.40.2 (Thu, 4 Jul 2024 09:59:17 +0200)
FSTESTVER: xfsprogs v6.10.1-91-g42523142 (Tue, 8 Oct 2024 14:31:31 +0200)
FSTESTVER: xfstests-bld 71bcf39c (Tue, 15 Oct 2024 13:27:36 -0400)
FSTESTVER: xfstests v2024.10.14-11-g173cdbc07 (Tue, 15 Oct 2024 09:31:29 -0400)
FSTESTVER: zz_build-distro bookworm
FSTESTSET: -g auto
FSTESTOPT: aex