cifs mount failing after kernel update to 4.12.14-95.32

This document (000019680) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 12SP4

Situation

A SLES 12SP4 client is mounting a cifs share from Dell/EMC VNX 5400 storage
After updating the kernel to 4.12.14-95.32 the cifs mount fails with:
 
CIFS: Attempting to mount //server/SHARE
[83577.276715] No dialect specified on mount. Default has changed to a more secure dialect, SMB2.1 or later (e.g. SMB3), from CIFS (SMB1). To use the less secure SMB1 dialect to access old servers which do not support SMB3 (or SMB2.1) specify vers=1.0 on mount.
Mounting and accessing files works when using vers=1.0 but since SMB1 protocol is not considered secure anymore this would just be a temporary workaround.

Using vers=2.1 or 3.0 or 3.0.2 the mount works but when trying to access the backend the response is "stale file handle" and the requested file cannot be accessed.

 

Resolution

For the combination of SLES with kernel 4.12.14-95.32 and above and the Dell/EMC VNX5400 storage with SMB exports there are multiple solutions available:
  • use mount option "noserverino" This does not rely on the inode reference the server provides and works around this issue.
  • Open a case with DELL/EMC support and request a Fix for the VNX5400 storage (see below).Use the kernel version as reference.
  • Finally, but not recommended (use at your own risk) use vers=1.0 as mount option. ATTENTION! This forces usage of SMB1 protocol which is considered insecure and should not be used anymore. In a secure environment for a short time it may be a workaround.

Cause

The SLES kernel and the VNX server software disagree about the format of the first 8 bytes of QFid in the server's response to a file query.  Dell/EMC engineering saw reason to fix this on the VNX.
See full story at https://lists.samba.org/archive/cifs-protocol/2019-November/003346.html

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:000019680
  • Creation Date: 12-Aug-2020
  • Modified Date:12-Aug-2020
    • SUSE Linux Enterprise Server

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