NFS: 'Permission denied' for attributes after file move

This document (000020367) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 12 SP5

Situation

A SLES machine acting as an NFS client to a 3rd party NFS Server was upgraded from SUSE Linux Enterprise Server 12 SP4 to SP5.  Then, on an NFS Mount, if a file is moved to a new location, subsequent directory listings give 'Permission denied' and display question marks instead of file attributes.

ls: cannot access 'subfolder/a.txt': Permission denied
total 16
drwxr-xr-x 2 root root 8192 Apr  1  2021 ./
drwxr-xr-x 4 root root 8192 Apr  1  2021 ../
?????????? ? ?    ?       ?            ? a.txt

 

Resolution

Check for unapplied updates for the 3rd party NFS Server for file handling.  (See Cause section, below.)

Until the NFS Server side can be corrected, possible workarounds include:

1.  At the NFS client, when mounting the share, include the "lookupcache=none' option.  This should avoid the problem altogether, although there could be a small performance penalty.

An example in a mount command:
mount -o lookupcache=none nfs-server1:/share1 /mnt

An example for /etc/fstab:
nfs-server1:/share1     /mnt     nfs     lookupcache=none  0  0

If #1 cannot be immediately implemented, alternatives 2 and 3 can be considered:

2.  It is likely that touching (setting a new time stamp) on the parent directory will cause the NFS client to flush enough cache to correct the problem.  If the problematic file is:
/mnt/subfolder/a.txt
Then execute:
touch /mnt/subfolder

3.  Dropping all disk caches at the NFS client machine will allow the client to learn new file handles, anywhere this problem has occurred.  However, this step can have a large impact and should only be used as a last resort.  Machine performance may suffer for a period of time after this is executed, because previously cached information from any/all file systems will have to be relearned from disk and/or from the NFS Server.
echo 3 > /proc/sys/vm/drop_caches

Cause

The 3rd party NFS Server is creating a new file handle for a moved file, rather than using the same file handle.  This is likely a violation of the NFS Protocol, as file handles are not allowed to depend upon the pathname of the object.  This requirement is intended to avoid file handle changes upon a rename or move.

The NFS Server in this case was using 3PAR/File Persona Version 1.6.0, and the behavior was fixed by upgrading to 1.6.1.

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:000020367
  • Creation Date: 25-Aug-2021
  • Modified Date:21-Sep-2021
    • SUSE Linux Enterprise Server

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