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

Question

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

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.

Sumarigo-MSFT 32,556 Reputation points Microsoft Employee

2020-12-21T11:52:33.787+00:00

@Nahush Bhanage As I understand: You are facing this error while creating a "Filename"? If possible can you share the script?

Additional information: Azure Files supports the most valid Unicode codepoints, so renaming meaningful file names into a Latin characterset is not required. Where Azure Files lags behind NTFS is its support for characters that should not be used in file names but NTFS allows anyway, such as invalid Unicode characters (like malformed multipart codepoints) and control characters.
Nahush Bhanage 1 Reputation point

2020-12-22T06:45:09.34+00:00

@Sumarigo-MSFT Thank you for looking into this. The error is while setting owner/group on an existing file after trying to create a file with an unsupported character. I've added the script with description in my comment above. Copying it here again for easy reference.

[root@af335-1]# > file1
[root@af335-1]# chown 0:0 file1
[root@af335-1]# > file1:
bash: file1:: Invalid argument
[root@af335-1]# chown 0:0 file1
chown: changing ownership of ‘file1’: Invalid argument

Last chown command should have worked. It fails only if I attempt to create "file:" which is an invalid name according to AF NFS documentation. Please also check the attached tcpdump traces for additional info.
Sumarigo-MSFT 32,556 Reputation points Microsoft Employee

2020-12-22T18:26:39.803+00:00

@Nahush Bhanage Here is the naming convention for files. Let me know if this is what you are looking for.

https://learn.microsoft.com/en-us/rest/api/storageservices/naming-and-referencing-shares--directories--files--and-metadata#share-names
Nahush Bhanage 1 Reputation point

2020-12-23T18:24:24.277+00:00

@Sumarigo-MSFT I'm aware of the naming convention for files. If I intentionally try to create a file with a name that's not supported, it fails as expected. But after that, I'm not able to change owner/group of existing files with valid names - that's the problem I need help with. Please check my script and the attached tcp traces. Thank you.
Sumarigo-MSFT 32,556 Reputation points Microsoft Employee

2021-01-01T05:59:32.683+00:00

@Nahush Bhanage Thanks for raising this question! Apologies for the delay in responding here. I'm checking on this internally with the product team and get back to you with something concrete on this issue.

Sumarigo-MSFT 32,556 Reputation points Microsoft Employee

2020-12-21T11:52:33.787+00:00

@Nahush Bhanage As I understand: You are facing this error while creating a "Filename"? If possible can you share the script?

Additional information: Azure Files supports the most valid Unicode codepoints, so renaming meaningful file names into a Latin characterset is not required. Where Azure Files lags behind NTFS is its support for characters that should not be used in file names but NTFS allows anyway, such as invalid Unicode characters (like malformed multipart codepoints) and control characters.
Nahush Bhanage 1 Reputation point

2020-12-22T06:45:09.34+00:00

@Sumarigo-MSFT Thank you for looking into this. The error is while setting owner/group on an existing file after trying to create a file with an unsupported character. I've added the script with description in my comment above. Copying it here again for easy reference.

[root@af335-1]# > file1
[root@af335-1]# chown 0:0 file1
[root@af335-1]# > file1:
bash: file1:: Invalid argument
[root@af335-1]# chown 0:0 file1
chown: changing ownership of ‘file1’: Invalid argument

Last chown command should have worked. It fails only if I attempt to create "file:" which is an invalid name according to AF NFS documentation. Please also check the attached tcpdump traces for additional info.
Sumarigo-MSFT 32,556 Reputation points Microsoft Employee

2020-12-22T18:26:39.803+00:00

@Nahush Bhanage Here is the naming convention for files. Let me know if this is what you are looking for.

https://learn.microsoft.com/en-us/rest/api/storageservices/naming-and-referencing-shares--directories--files--and-metadata#share-names
Nahush Bhanage 1 Reputation point

2020-12-23T18:24:24.277+00:00

@Sumarigo-MSFT I'm aware of the naming convention for files. If I intentionally try to create a file with a name that's not supported, it fails as expected. But after that, I'm not able to change owner/group of existing files with valid names - that's the problem I need help with. Please check my script and the attached tcp traces. Thank you.
Sumarigo-MSFT 32,556 Reputation points Microsoft Employee

2021-01-01T05:59:32.683+00:00

@Nahush Bhanage Thanks for raising this question! Apologies for the delay in responding here. I'm checking on this internally with the product team and get back to you with something concrete on this issue.

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

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