kernel-packages team mailing list archive

[Bryan Quigley <gQuigs@xxxxxxxxx>]

A tunable can be set in AIX 7.1 that forces better syncronization which
avoids this issue.

** Changed in: linux (Ubuntu)
       Status: Incomplete => Invalid

-- 
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1167420

Title:
   NFSv4 CLOSE/LOCK-operation needs timing improvement for AIX compat

Status in “linux” package in Ubuntu:
  Invalid

Bug description:
  We're mounting our users' home directories via NFSv4 from a server
  running AIX 7.1. When a process on an Ubuntu 12.04 client locks a file
  accessed via NFSv4 using flock() and afterwards closes it, the close()
  sometimes blocks for 15 seconds.

  The cause of the problem turned out to be a race condition between the
  NFSv4 operations CLOSE and RELEASE_LOCKOWNER. The client sends CLOSE
  immediately after RELEASE_LOCKOWNER, without waiting for the reply
  for RELEASE_LOCKOWNER (which is completely fine to do per NFS RFC, but not what AIX was expecting). Sometimes it happens that the server tries to process the CLOSE before RELEASE_LOCKOWNER has finished. In that case
  it replies to the CLOSE with NFS4ERR_DELAY, which causes the client to
  retry the CLOSE after 15 seconds.

  Ubuntu should instead of freezing for 15 seconds retry sooner and then exponentially increase the timeout up to 15 sec.
  This should make the client more responsive in other cases, while increasing compatibility with AIX 7.1's implementation issues.

  OS: Ubuntu 12.04 / AIX 7.1.   Not fixed in upstream Linux releases.

  Steps to Reproduce:
    gcc -o open-close open-close.c
    touch testfile # create file to be used by open-close
    for i in `seq 100`; do ./open-close; done

  Happens 10% of the time.

  Relevant NFS mailing list discussion: https://www.ietf.org/mail-
  archive/web/nfsv4/current/msg11720.html

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1167420/+subscriptions