Azure Files NFS: changing owner/group fails with invalid argument

Question

Client info

CentOS Linux release 7.8.2003
Kernel 4.19.134-300.el7.x86_64
Azure Files share mounted over NFSv4.1
ID mapping disabled on client

Repro steps

1) Create a file named "file1". Works fine.
[root@af335-1]# > file1

2) Change owner/group of "file1". Works fine.
**[root@af335-1]# chown 0:0 file1 **

3) Try to create a file named "file1:" Fails with invalid argument as expect. (colon is not allowed in paths as documented in https://learn.microsoft.com/en-us/rest/api/storageservices/naming-and-referencing-shares--directories--files--and-metadata, so this file creation fails as expected)
[root@af335-1]# > file1:
bash: file1:: Invalid argument

4) Change owner/group of "file1" (same command as #2). Fails with invalid argument.
[root@af335-1]# chown 0:0 file1
chown: changing ownership of ‘file1’: Invalid argument

Workaround

Need to unmount and remount the share to get chown working again. No issues if I skip step #3.

Troubleshooting

Tcpdump shows

• chown in step #2 sends numeric UID/GID (0) in SETATTR and that works fine
• however the same chown command in step #4 sends alphanumeric UID/GID (root@localdomain) in SETATTR and that fails with invalid argument (alphanumeric UID/GID not supported by Azure Files as documented in https://learn.microsoft.com/en-us/azure/storage/files/storage-files-compare-protocols)

Question: How does step #3 (attempting to create files with names containing unsupported characters) cause the NFS client to send alphanumeric UID/GID instead of numeric values?

Please let me know if you need more info from my end. Thank you.

Answer 1

@Nahush Bhanage Apologies for the delay! We found the root cause. You are getting this “:” (not supported ) in their file/dir name causing server to send BADNAME.

Upon getting this exception, the client re-enables id-mapping. Can you disable id-mapping, but the bigger problem is even if a file/dir is even tried to be created with “:” name, the server sends BADNAME error. NFS client upon getting this BADNAME exception re-enables id-mapping, now the setting which was made to disable id-mapping is enabled/reset back.

We are in the process of supporting the special characters and it will be available very soon I will keep you update once the special character is been fixed.

Hope this helps!

Kindly let us know if the above helps or you need further assistance on this issue.

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