Date: Thu, 20 May 2021 20:36:58 -0700 From: Mark Millard <marklmi@yahoo.com> To: Rick Macklem <rmacklem@uoguelph.ca> Cc: FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org> Subject: Re: releng/13 release/13.0.0 : odd/incorrect diff result over nfs (in a zfs file systems context) Message-ID: <34E915B3-30DF-408C-A931-C39188F3EB0F@yahoo.com> In-Reply-To: <04D7264A-206B-4281-B452-779B01EA3327@yahoo.com> References: <623369D9-5EE5-4FEF-B9AD-56499E8F1C09.ref@yahoo.com> <623369D9-5EE5-4FEF-B9AD-56499E8F1C09@yahoo.com> <YQXPR0101MB0968B29934D7BD73FCA73907DD299@YQXPR0101MB0968.CANPRD01.PROD.OUTLOOK.COM> <YTOPR0101MB0970A1257E4DD37335D5B52EDD299@YTOPR0101MB0970.CANPRD01.PROD.OUTLOOK.COM> <04D7264A-206B-4281-B452-779B01EA3327@yahoo.com>
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[stable/13 test: example ends up being odder. That might
allow eliminating some potential alternatives.]
On 2021-May-20, at 19:38, Mark Millard <marklmi at yahoo.com> wrote:
>=20
> On 2021-May-20, at 18:09, Rick Macklem <rmacklem@uoguelph.ca> wrote:
>>=20
>> Oh, one additional thing that I'll dare to top post...
>> r367492 broke the TCP upcalls that the NFS server uses, such
>> that intermittent hangs of NFS mounts to FreeBSD13 servers can occur.
>> This has not yet been resolved in "main" etc and could explain
>> why an RPC could time out for a soft mount.
>=20
> See later notes that I added: soft mount is not required
> to see the problem.
>=20
>> You can revert the patch in r367492 to avoid the problem.
>=20
> If I understand right, you are indicating that this would
> not apply to the non-soft mount case that I got.
>=20
>> Disabling TSO, LRO are also de-facto standard things to do when
>> you observe weird NFS behaviour, because they are often broken
>> in various network device drivers.
>=20
> I'll have to figure out how to experiment with such. Things
> are at defaults rather generally on the systems. I'm not
> literate in the subject areas.
>=20
> I'm the only user of the machines and network. It is not
> outward facing. It is a rather small EtherNet network.
>=20
>> rick
>>=20
>> ________________________________________
>> From: owner-freebsd-stable@freebsd.org =
<owner-freebsd-stable@freebsd.org> on behalf of Rick Macklem =
<rmacklem@uoguelph.ca>
>> Sent: Thursday, May 20, 2021 8:55 PM
>> To: FreeBSD-STABLE Mailing List; Mark Millard
>> Subject: Re: releng/13 release/13.0.0 : odd/incorrect diff result =
over nfs (in a zfs file systems context)
>>=20
>> Mark Millard wrote:
>>> [I warn that I'm a fairly minimal user of NFS
>>> mounts, not knowing all that much. I'm mostly
>>> reporting this in case it ends up as evidence
>>> via eventually matching up with others observing
>>> possibly related oddities.]
>>>=20
>>> I got the following odd sequence (that I've
>>> mixed notes into). It involved a diff -r over NFS
>>> showing differences (files missing) and then a
>>> later diff finding matches for the same files,
>>> no file system changes made on either machine.
>>> I'm unable to reproduce the oddity on demand.
>>>=20
>>> Note: A larger scope diff -r originally returned the
>>> below as well, but doing the narrower diff -r did
>>> repeat the result and that is what I show. (I
>>> make no use of devel/ice .)
>>>=20
>>> # diff -r /usr/ports/devel/ice/files /mnt/devel/ice/files | more
>>> Only in /usr/ports/devel/ice/files: Make.rules.FreeBSD
> . . .
>>> Only in /usr/ports/devel/ice/files: patch-scripts-TestUtil.py
>>>=20
>>> Note: The above was not expected. So I tried:
>>>=20
>>> # ls -Tld /mnt/devel/ice/files/*
>>> -rw-r--r-- 1 root wheel 755 Apr 21 21:07:54 2021 =
/mnt/devel/ice/files/Make.rules.FreeBSD
> . . .
>>> -rw-r--r-- 1 root wheel 2588 Apr 21 21:07:54 2021 =
/mnt/devel/ice/files/patch-scripts-TestUtil.py
>>>=20
>>> Note: So that indicated that the files were there on the
>>> machine that /mnt references. So attempting the original
>>> diff -r again:
>>>=20
>>> # diff -r /usr/ports/devel/ice/files /mnt/devel/ice/files | more
>>> #
>>>=20
>>> (Empty difference.)
>>>=20
>>> Note: So after the explicit "ls -Tld /mnt/devel/ice/files/*"
>>> the odd result of the diff -r no longer happened: no
>>> differences reported.
>>>=20
>>>=20
>>>=20
>>> For reference (both machines reported):
>>>=20
>>> . . .
>>> The original mount command was on CA72_16Gp_ZFS:
>>>=20
>>> # mount -onoatime,soft 192.168.1.170:/usr/ports/ /mnt/
>> The likely explanation for this is your use of a "soft" mount.
>> - If the NFS server is slow to respond or there is a temporary =
network issue,
>> the RPC request can time out and then the
>> syscall can fail with EINT/ETIMEDOUT. Since almost nothing, =
including the
>> readdir(3) libc functions expect syscalls to fail this way...
>> Then the cached directory is messed up.
>> Doing the "ls" read the directory again and fixed the problem.
>>=20
>> Try to reproduce it for a mount without the "soft" option.
>> (If a mount point is hung, due to an unresponsive server "umount -N =
/mnt"
>> can usually get rid of it.)
>> Personally, I thought "soft" was a bad idea when Sun introduced it in =
NFS in 1985
>> and I still feel that way.
>> --> If you can reproduce it without "soft" then I can't explain it.
>> To be honest, the directory reading/caching code in the NFSv3 =
client
>> hasn't changed significantly in literally decades, as far as I =
can remember.
>=20
> Well . . . trying an even wider scope diff than
> the original . . .
>=20
> # umount /mnt/
> # mount -onoatime 192.168.1.170:/usr/ports/ /mnt/
> # diff -r /usr/ports/ /mnt/ | more
> Only in /mnt/databases/mongodb42/files/aarch64: =
patch-src_third__party_mozjs-60_
> Only in /usr/ports/databases/mongodb42/files/aarch64: =
patch-src_third__party_mozjs-60_platform_aarch64_freebsd_build_Unified__cp=
p__js__src25.cpp
> Only in /usr/ports/devel/ice/files: Make.rules.FreeBSD
> Only in /usr/ports/devel/ice/files: patch-config-Make.common.rules
> Only in /usr/ports/devel/ice/files: patch-cpp-Makefile
> . . .
> Only in /usr/ports/devel/ice/files: =
patch-python-test-Slice-unicodePaths-run.py
> Only in /usr/ports/devel/ice/files: patch-scripts-Expect.py
> Only in /usr/ports/devel/ice/files: patch-scripts-IceGridAdmin.py
> Only in /usr/ports/devel/ice/files: patch-scripts-TestUtil.py
>=20
> So the devel/ice files showed up again.
>=20
> But 2 other lines show up, one finding a file supposedly only
> on /mnt/. . .
>=20
> QUOTE
> Only in /mnt/databases/mongodb42/files/aarch64: =
patch-src_third__party_mozjs-60_
> END QUOTE
>=20
> That seems to be a truncated file name. Looking directly on the =
machine that
> /mnt/ references (hitting tab at the end of the partial name to show a
> list):
>=20
> # ls -Tld =
/usr/ports/databases/mongodb42/files/aarch64/patch-src_third__party_mozjs-=
60_
> =
/usr/ports/databases/mongodb42/files/aarch64/patch-src_third__party_mozjs-=
60_gen-config.sh =20
> =
/usr/ports/databases/mongodb42/files/aarch64/patch-src_third__party_mozjs-=
60_platform_aarch64_freebsd_build_js-confdefs.h =20
> =
/usr/ports/databases/mongodb42/files/aarch64/patch-src_third__party_mozjs-=
60_platform_aarch64_freebsd_build_Unified__cpp__js__src0.cpp =20
> =
/usr/ports/databases/mongodb42/files/aarch64/patch-src_third__party_mozjs-=
60_platform_aarch64_freebsd_build_Unified__cpp__js__src1.cpp =20
> . . . =20
> =
/usr/ports/databases/mongodb42/files/aarch64/patch-src_third__party_mozjs-=
60_platform_aarch64_freebsd_build_Unified__cpp__js__src9.cpp =20
> =
/usr/ports/databases/mongodb42/files/aarch64/patch-src_third__party_mozjs-=
60_platform_aarch64_freebsd_include_js-config.h =20
>=20
> The other machine agrees (machine-local usage).
>=20
> The other of the 2 new names is one of the matches to the prefix:
>=20
> QUOTE
> Only in /usr/ports/databases/mongodb42/files/aarch64: =
patch-src_third__party_mozjs-60_platform_aarch64_freebsd_build_Unified__cp=
p__js__src25.cpp
> END QUOTE
>=20
> For reference: I've not gotten any console messages about
> anything during these.
>=20
>> One additional thing to note is that cached directory contents are =
invalidated
>> when the directory's ctime changes.
>=20
> I'm not aware of anything that should have been touching the
> /usr/ports file systems on either machine any time near my
> diff activities. (I'm the only system user.)
>=20
>> I am not sure how/if/when ZFS changes a
>> directory's ctime. However, if it was badly broken, I'd hear about =
this a lot.
>> (If the ZFS change to ZoL has changed its ctime handling, that might =
also explain it
>> and I'll be hearing a lot more soon as FreeBSD13 becomes adopted. I =
never use ZFS and,
>> as such, never test with it.)
>=20
> I recently decided to try using bectl, which lead to my recent
> ZFS-based system experiments.
>=20
> This means I can boot the stable/13 or main [so: 14] that
> I last built and try the same experiments with the same
> /usr/ports file sysystems. releng/13 's release/13.0.0 ,
> stable/13 , and main are all non-debug builds as stands. I
> could add debug builds of any or all, but it would take
> a while. (aarch64 4-core Cortex-A72 contexts.)
>=20
>> --> For UFS, if you use mtime, directory caching does not work as =
well, which is
>> why the client directory caching code uses ctime and not mtime =
to detect that
>> a directory has changed and cached directory blocks need to be =
invalidated.
>>=20
>> Jason Bacon did report a directory reading issue some months ago that =
never
>> quite got resolved, although I recall he said he couldn't reproduce =
it after a
>> system update, so he thought it was related to some local change he =
had made.
>> (I can't remember his email or I'd add him to the cc so he could =
remind me what
>> his case was. I do recall it being somewhat reproducible and happened =
for both
>> UFS and ZFS.)
>>> The network is just a local EtherNet.
>>=20
>=20
stable/13 got similar "diff -r /usr/ports/ /mnt/ | more" results but
/mnt/devel/electron12/files indications of the =
/usr/ports/devel/ice/files
ones. It did again start with:
Only in /mnt/databases/mongodb42/files/aarch64: =
patch-src_third__party_mozjs-60_
Only in /usr/ports/databases/mongodb42/files/aarch64: =
patch-src_third__party_mozjs-60_platform_aarch64_freebsd_build_Unified__cp=
p__js__src25.cpp
for this rather wide range diff -r . It continued with:
Only in /mnt/devel/electron12/files:=20
Only in /mnt/devel/electron12/files: package.json
Only in /mnt/devel/electron12/files: =
patch-apps_ui_views_app__window__frame__view.cc
Only in /mnt/devel/electron12/files: =
patch-ash_display_mirror__window__controller.cc
Only in /mnt/devel/electron12/files: patch-base_BUILD.gn
. . .
It finished with:
Only in /mnt/devel/electron12/files: yarn.lock
Only in /mnt/devel/electron12/files: <A0><CE><C8>=D6=8F<DC>=DC=A62<B2><E2>=
<AA>^H
Only in /mnt/www/chromium/files: patch-chrome_browser_chrome__browser
Only in /usr/ports/www/chromium/files: =
patch-chrome_browser_chrome__browser__main__posix.cc
That last is the only /usr/ports/ prefixed path this time: the
only one where it was under /mnt/ that something appeared to
be missing.
It appears that the file name on the line after the yarn.lock
line is garbage with no matching file present when using ls
on the system that /mnt/ references.
Locally on each machine the devel/electron12/files/* files
are shown by ls as present ( through yarn.lock ).
NOTE:
I find it odd that the local /usr/ports/ ended up being where
most of the files were reported as missing, instead of under
/mnt/ : Wrong side for a network/network-protocol issue?
For reference (David W. indicated I should look at ifconfig
for figuring out controlling TSO and such so I figured I'd
show the default ifconfig output):
# ifconfig
lo0: flags=3D8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
options=3D680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
inet6 ::1 prefixlen 128
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1
inet 127.0.0.1 netmask 0xff000000
groups: lo
nd6 options=3D21<PERFORMNUD,AUTO_LINKLOCAL>
ue0: flags=3D8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu =
1500
=
options=3D68009b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,LINKSTA=
TE,RXCSUM_IPV6,TXCSUM_IPV6>
ether REPLACED
inet 192.168.1.148 netmask 0xffffff00 broadcast 192.168.1.255
media: Ethernet autoselect (1000baseT <full-duplex>)
status: active
nd6 options=3D29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
# ifconfig
genet0: flags=3D8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 =
mtu 1500
=
options=3D68000b<RXCSUM,TXCSUM,VLAN_MTU,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>=
ether REPLACED
inet6 REPLACED%genet0 prefixlen 64 scopeid 0x1
inet6 REPLACED prefixlen 64 autoconf
inet 192.168.1.170 netmask 0xffffff00 broadcast 192.168.1.255
media: Ethernet autoselect (1000baseT <full-duplex>)
status: active
nd6 options=3D23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
lo0: flags=3D8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
options=3D680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
inet6 ::1 prefixlen 128
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2
inet 127.0.0.1 netmask 0xff000000
groups: lo
nd6 options=3D21<PERFORMNUD,AUTO_LINKLOCAL>
# uname -apKU
FreeBSD CA72_16Gp_ZFS 13.0-STABLE FreeBSD 13.0-STABLE #1 =
stable/13-n245474-fb34817c686c-dirty: Sat May 1 02:27:02 PDT 2021 =
root@CA72_4c8G_ZFS:/usr/obj/BUILDs/13S-CA72-nodbg-clang/usr/13S-src/arm64.=
aarch64/sys/GENERIC-NODBG-CA72 arm64 aarch64 1300504 1300504
# ~/fbsd-based-on-what-commit.sh=20
branch: stable/13
merge-base: fb34817c686cc130449325499870e36979899801
merge-base: CommitDate: 2021-05-01 00:56:57 +0000
fb34817c686c (HEAD -> stable/13, freebsd/stable/13) param.h: bump =
__FreeBSD_version for commits efe7f12cd37b and 9781105bea58
n245474 (--first-parent --count for merge-base)
# uname -apKU
FreeBSD CA72_4c8G_ZFS 13.0-STABLE FreeBSD 13.0-STABLE #1 =
stable/13-n245474-fb34817c686c-dirty: Sat May 1 02:27:02 PDT 2021 =
root@CA72_4c8G_ZFS:/usr/obj/BUILDs/13S-CA72-nodbg-clang/usr/13S-src/arm64.=
aarch64/sys/GENERIC-NODBG-CA72 arm64 aarch64 1300504 1300504
# ~/fbsd-based-on-what-commit.sh=20
branch: stable/13
merge-base: fb34817c686cc130449325499870e36979899801
merge-base: CommitDate: 2021-05-01 00:56:57 +0000
fb34817c686c (HEAD -> stable/13, freebsd/stable/13) param.h: bump =
__FreeBSD_version for commits efe7f12cd37b and 9781105bea58
n245474 (--first-parent --count for merge-base)
=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)
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