[Bug 2033892] Re: ls -l triggers mount of autofs shares when --ghost option is present or browse_mode is enabled

Thu Mar 21 16:09:30 UTC 2024

For dotnet6 on amd64 and arm64, the errors are unrelated to coreutils
(the same test errors happen against dotnet6 itself and even glibc),
thus triggered a migration-reference/0 run.

[0,3] trigger: coreutils/8.32-4.1ubuntu1.2
	dotnet-runtime-json-contains-ubuntu-rids FAIL non-zero exit status 253

[1,4] trigger: dotnet6/6.0.128-0ubuntu1~22.04.1
	dotnet-runtime-json-contains-ubuntu-rids FAIL non-zero exit status 253

[2,5] trigger: glibc/2.35-0ubuntu3.6
	dotnet-runtime-json-contains-ubuntu-rids FAIL non-zero exit status 253

All fail with error messages:
	ERROR: RID (Runtime Identifier) 'ubuntu.24.04{,-arm,-arm64,-x64,-x86}' is missing in 'src/runtime/src/libraries/Microsoft.NETCore.Platforms/src/runtime.json'!

[0] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy/jammy/amd64/d/dotnet6/20240319_131027_34202@/log.gz
[1] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy/jammy/amd64/d/dotnet6/20240321_145231_25ae8@/log.gz
[2] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy/jammy/amd64/d/dotnet6/20240321_154527_e413f@/log.gz

[3] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy/jammy/arm64/d/dotnet6/20240319_111747_74352@/log.gz
[4] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy/jammy/arm64/d/dotnet6/20240321_135858_e04d0@/log.gz
[5] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy/jammy/arm64/d/dotnet6/20240321_141049_ff5d1@/log.gz

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https://bugs.launchpad.net/bugs/2033892

Title:
  ls -l triggers mount of autofs shares when --ghost option is present
  or browse_mode is enabled

Status in coreutils package in Ubuntu:
  Fix Released
Status in coreutils source package in Jammy:
  Fix Committed
Status in coreutils package in Fedora:
  Fix Released

Bug description:
  [Impact]

  Issuing a 'ls -l' or a 'stat' on an autofs share when you have set
  --ghost in the auto.master file, or browse_mode=yes in autofs.conf
  will lead to the shares being mounted, when they didn't previously.

  Disks / shares may not be present and the mounts may fail, leading to
  errors in your output.

  This is a behaviour change in autofs 8.32, which occurred in the
  transition to using statx() instead of stat()/lstat() in previous
  releases.

  There doesn't seem to be any workarounds, apart from not running a 'ls
  -l' in your autofs share directory.

  [Testcase]

  Start two Jammy VMs. One will be a NFS server, the other, the client.

  NFS server:

  Server VM:
  $ sudo hostnamectl set-hostname jammy-nfs-server
  $ sudo apt update && sudo apt upgrade -y
  $ sudo apt install nfs-kernel-server
  $ sudo mkdir /export
  $ sudo mkdir /export/users
  $ sudo vi /etc/exports # add the following lines:
  /export 192.168.122.0/24(rw,fsid=0,no_subtree_check,sync)
  /export/users 192.168.122.0/24(rw,nohide,insecure,no_subtree_check,sync)
  $ sudo systemctl restart nfs-server.service

  AutoFS Client:
  $ sudo apt update
  $ sudo apt install autofs
  $ sudo vim /etc/autofs.conf
  browse_mode = yes
  $ sudo mkdir /mnt2
  $ sudo vim /etc/auto.master
  /mnt2 /etc/auto.indirect
  $ sudo vim /etc/auto.indirect
  export 192.168.122.18:/export
  export-missing 192.168.122.18:/export-missing
  $ sudo reboot
  $ cd /mnt2
  $ ls -l
  ls: cannot access 'export-missing': No such file or directory
  total 4
  drwxr-xr-x 3 root root 4096 Feb 12 21:48 export
  d????????? ? ?    ?       ?            ? export-missing
  $ mount -l | grep /mnt2
  /etc/auto.indirect on /mnt2 type autofs (rw,relatime,fd=6,pgrp=634,timeout=300,minproto=5,maxproto=5,indirect,pipe_ino=21561)
  192.168.122.18:/export on /mnt2/export type nfs (rw,relatime,vers=3,rsize=524288,wsize=524288,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=192.168.122.18,mountvers=3,mountport=35786,mountproto=udp,local_lock=none,addr=192.168.122.18)

  We see the mount for export occurred, and export-missing was
  attempted, but it was either bogus or the disk was not present,
  leading to a "No such file or directory" error.

  There are test packages available in the following ppa:

  https://launchpad.net/~mruffell/+archive/ubuntu/sf378489-test

  If you install them, this is what should occur:

  $ ls -l
  total 0
  drwxr-xr-x 2 root root 0 Feb 12 22:01 export
  drwxr-xr-x 2 root root 0 Feb 12 22:01 export-missing
  $ mount -l | grep /mnt2
  /etc/auto.indirect on /mnt2 type autofs (rw,relatime,fd=6,pgrp=636,timeout=300,minproto=5,maxproto=5,indirect,pipe_ino=18346)

  No mounts happen, and no errors either.

  [Where problems could occur]

  We are changing the behaviour of core utilities, ls and stat, such
  that they no longer attempt to mount autofs shares when --ghost option
  is present or browse_mode is enabled.

  This is the intended behaviour in the first place, and has been this
  way for at least a decade prior, and was changed to return to this
  behaviour shortly after the release of coreutils that introduced
  statx() that caused automounts to occur.

  It is unlikely any system administrators are relying on the behaviour
  found in jammy in any scripts or day to day operations that would be
  adversely affected by the change. The worst case scenario is that a
  user doing an 'ls -l' on an unmounted disk finds the mount doesn't
  automatically occur, and they have to attach the disk and issue the
  mount themselves.

  If a regression were to occur, it would be limited to the ls and stat
  commands, specifically when listing directories linked to autofs
  mountpoints.

  [Other info]

  The automount behaviour change was introduced upstream in version
  8.32, with the introduction of the statx() call. This means only Jammy
  is affected.

  It was quickly reverted back to how it was originally in version 9.1,
  which is already available in Mantic and onward.

  The commits that solve the issue are:

  commit 85c975df2c25bd799370b04bb294e568e001102f
  From: Rohan Sable <rsable at redhat.com>
  Date: Mon, 7 Mar 2022 14:14:13 +0000
  Subject: ls: avoid triggering automounts
  Link: https://git.savannah.gnu.org/gitweb/?p=coreutils.git;a=commitdiff;h=v9.0-177-g85c975df2c2

  commit 92cb8427c537f37edd43c5cef1909585201372ab 
  From: Pádraig Brady <P at draigBrady.com>
  Date: Mon, 7 Mar 2022 23:29:20 +0000
  Subject: stat: only automount with --cached=never
  Link: https://git.savannah.gnu.org/gitweb/?p=coreutils.git;a=commitdiff;h=v9.0-178-g92cb8427c53

  Upstream bugs:
  https://bugs.gnu.org/54286
  https://bugs.gnu.org/54287

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