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[Bug 1686679] Re: [SRU] Ubuntu16.04 : autofs is extremely long with large number of direct maps

 

This bug did not have its tasks automatically modified because they are
about the autofs5 package, which only exists in Precise, and not the
autofs package.

** Package changed: autofs5 (Ubuntu) => autofs (Ubuntu)

** Changed in: autofs (Ubuntu Xenial)
       Status: Fix Committed => Fix Released

** Changed in: autofs (Ubuntu Yakkety)
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1686679

Title:
  [SRU] Ubuntu16.04 : autofs is extremely long with large number of
  direct maps

Status in autofs package in Ubuntu:
  Fix Released
Status in autofs source package in Xenial:
  Fix Released
Status in autofs source package in Yakkety:
  Fix Released

Bug description:
  [Impact]

  autofs service in xenial takes extremely long time since it parses the
  mount table /etc/mtab in contained_in_local_fs() to determine if the mount
  patch would be created on a local file system, that means startup process will read /etc/mtab for every mount, so the performance is extremely low. The customer is complaining about this point, we need to backport the
  following upstream patch.

  https://git.kernel.org/pub/scm/linux/storage/autofs/autofs.git/commit/?id=67e7d613a4b09eeffc57ab44a7acb52027d897b2

  This fix patch removes contained_in_local_fs, and use fs.f_type in is_remote_fstype() to determine if the mount patch would be created on a
   local file system instead.

  [Test Case]

   * Create an autofs direct mount map with large direct mappings (eg:
  8k), below is the test script I used.

  echo "/-      auto.direct        --timeout 60" >> /etc/auto.master
  END=8000
  for i in $(seq 1 $END); do echo $i; echo "/test/samba/test"$i" -fstype=cifs,rw,username=hua,password=password ://192.168.99.169/share" >> /etc/auto.direct; done

   * Start autofs service to see if it will take too much time, below is my
   result before/after applying the fix patch.

  root@node1:~# time service autofs start
  real	3m5.481s
  user	0m0.256s
  sys	0m0.080s
  root@node1:~# time service autofs start
  real	0m0.833s
  user	0m0.000s
  sys	0m0.004s

  [Regression Potential]

  * We are well aware of the principle of this fix patch - avoiding parsing
  the mount table to improve startup time, so seems infinitely better for
  all cases.

  * This fix from upstream has been backported into Redhat as well, and both
   me and customer have positive test results with automount start timings.

  * What releases to fix

  $ git tag --contains 67e7d613a4b09eeffc57ab44a7acb52027d897b2
  release_5_1_2

  $ rmadison autofs5
   autofs5 | 5.1.1-1ubuntu3 | xenial | all
   autofs5 | 5.1.1-1ubuntu3 | yakkety | all
   autofs5 | 5.1.2-1ubuntu1 | zesty | all
   autofs5 | 5.1.2-1ubuntu1 | artful | all

  $ rmadison -u debian autofs5
   autofs5    | 5.1.2-1        | unstable        | all

  - Ubuntu : Only Xenial and Yakkety are affected.
  Zesty and Artful already has the upstream fix because they are at version 5.1.2.

  - Debian : unstable also has the fix already.

  [Other Info]

  * Redhat [1] also already backported the following patch, see: https://bugzilla.redhat.com/show_bug.cgi?id=1440769
  * This mailing list also discussed this problem, see: http://www.spinics.net/lists/autofs/msg01161.html

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