Access to CIFS mounts fail after working for a period of time
This document (000021058) is provided subject to the disclaimer at the end of this document.
Environment
SUSE Linux Enterprise Server 12 SP5
Situation
SLES 12 SP5 systems with CIFS mounts can use them successfully for a while, but after some period of time, access to the CIFS-mounted file system fails. For example, in one case, various attempts to use the mount returned the error:
Bad file descriptor
In another case, access attempts appeared to hang or stall. Tcpdump reveals that various operations are still being attempted, but looping on errors such as STATUS_FILE_CLOSED or STATUS_TOO_MANY_OPENED_FILES.
The problem can be temporarily solved by umounting and mounting again, but the behavior will eventually come back.
This may be coincidental, but this behavior was found after updating from SLES 12 SP4 to SLES 12 SP5.
Bad file descriptor
In another case, access attempts appeared to hang or stall. Tcpdump reveals that various operations are still being attempted, but looping on errors such as STATUS_FILE_CLOSED or STATUS_TOO_MANY_OPENED_FILES.
The problem can be temporarily solved by umounting and mounting again, but the behavior will eventually come back.
This may be coincidental, but this behavior was found after updating from SLES 12 SP4 to SLES 12 SP5.
Resolution
A problem was identified in the caching of the root file handle of the CIFS share.
A workaround is to add "nohandlecache" to the CIFS mount options.
A code fix is available. Update to the early May 2023 maintenance kernel version:
SLES 12 SP5: Kernel 4.12.14-122.159.1.
SLES 12 SP5 Real Time: Kernel 4.12.14-10.124.1
SLES 12 SP5 Azure: Kernel 4.12.14-16.133.1
This issue is not expected to effect SLES 15 SP4 (or higher), which uses a 5.14.21 kernel. In 15 SP4, the relevant caching features have been expanded and enhanced, and the precise cause should no longer exist.
However, due to ongoing changes to 15 SP4, if a similar issue is encountered on SLES 15, it is suggested to update to the latest available kernel.
A workaround is to add "nohandlecache" to the CIFS mount options.
A code fix is available. Update to the early May 2023 maintenance kernel version:
SLES 12 SP5: Kernel 4.12.14-122.159.1.
SLES 12 SP5 Real Time: Kernel 4.12.14-10.124.1
SLES 12 SP5 Azure: Kernel 4.12.14-16.133.1
This issue is not expected to effect SLES 15 SP4 (or higher), which uses a 5.14.21 kernel. In 15 SP4, the relevant caching features have been expanded and enhanced, and the precise cause should no longer exist.
However, due to ongoing changes to 15 SP4, if a similar issue is encountered on SLES 15, it is suggested to update to the latest available kernel.
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:000021058
- Creation Date: 11-May-2023
- Modified Date:11-May-2023
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- SUSE Linux Enterprise Server
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