[Bug 1557507] [NEW] rpc.mountd high CPU usage

[Owen Dunn]

Public bug reported:

Description:    Ubuntu 14.04.3 LTS
Release:        14.04

nfs-kernel-server version 1:1.2.8-6ubuntu1.2

I have a system with ~1900 ZFS filesystems, which I am exporting over
NFS.

When one of these filesystems is mounted by a client rpc.mountd on the
server climbs to 100% CPU.  stracing rpc.mountd reveals that it is calling
newfstat() for every device on the system addressed by every possible
route for every export.  (I've attached a fragment of the strace output.)

This seems to be the problem described in this thread:

http://www.spinics.net/lists/linux-nfs/msg40946.html

and applying the patch at:

http://www.spinics.net/lists/linux-nfs/msg41193.html

fixed the problem for me.  Could this patch be applied to the Ubuntu package,
please?

Owen

** Affects: nfs-utils (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1557507

Title:
  rpc.mountd high CPU usage

Status in nfs-utils package in Ubuntu:
  New

Bug description:
  Description:    Ubuntu 14.04.3 LTS
  Release:        14.04

  nfs-kernel-server version 1:1.2.8-6ubuntu1.2

  I have a system with ~1900 ZFS filesystems, which I am exporting over
  NFS.

  When one of these filesystems is mounted by a client rpc.mountd on the
  server climbs to 100% CPU.  stracing rpc.mountd reveals that it is calling
  newfstat() for every device on the system addressed by every possible
  route for every export.  (I've attached a fragment of the strace output.)

  This seems to be the problem described in this thread:

  http://www.spinics.net/lists/linux-nfs/msg40946.html

  and applying the patch at:

  http://www.spinics.net/lists/linux-nfs/msg41193.html

  fixed the problem for me.  Could this patch be applied to the Ubuntu package,
  please?

  Owen

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