[Bug 709392] Re: NFS client does not submit "nfs_file_sync" write requests when the file open call includes O_SYNC.

[Steve Langasek]

The upstream kernel task has been marked as resolved; I think that means
this bug should be assigned to the linux package for fixing in Lucid.

** Package changed: nfs-utils (Ubuntu) => linux (Ubuntu)

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https://bugs.launchpad.net/bugs/709392

Title:
  NFS client does not submit "nfs_file_sync" write requests when the
  file open call includes O_SYNC.

Status in The Linux Kernel:
  Fix Released
Status in “linux” package in Ubuntu:
  Triaged
Status in “linux” source package in Lucid:
  Triaged

Bug description:
  The NFS Client is ignoring O_SYNC when opening a file.

  This bug is causing unstable writes in the application environment even
  when the mount option "sync" is set on both sides (NFS client and server).

  We have a test case shows that the Ubuntu NFS client does
  not submit "nfs_file_sync" write requests when the file open call
  includes O_SYNC.

  I have strace and tcpdump data showing this issue.  The strace shows that
  the file is opened with O_SYNC. The tcpdump shows "unstable writes"
  which should not occur with either "sync" mount option or with forced
  sync by using the open file system call with O_SYNC.  Comparing the
  tcpdump data between the Ubuntu NFS client a RHEL NFS client shows
  that the Ubuntu NFS client does not issue the "nfs_file_sync" write
  requests, while the RHEL NFS client does.

  This issue does not appear to be tied to a specific model of storage
  array or a specific file system. Tests have been performed against an NFS
  server having access to a GPFS file system where a SAN attached IBM
  DS5300 is the underlying storage array.  But the behaviour is exactly
  the same when they export a local ext3 file system from the local scsi
  disk.

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