Re: [PATCH v6 4/6] fs: make vfs_fileattr_[get|set] return -EOPNOSUPP

[Arnd Bergmann]

On Mon, Oct 6, 2025, at 13:09, Jiri Slaby wrote:
> On 30. 06. 25, 18:20, Andrey Albershteyn wrote:
>> Future patches will add new syscalls which use these functions. As
>> this interface won't be used for ioctls only, the EOPNOSUPP is more
>> appropriate return code.
>> 
>> This patch converts return code from ENOIOCTLCMD to EOPNOSUPP for
>> vfs_fileattr_get and vfs_fileattr_set. To save old behavior translate
>> EOPNOSUPP back for current users - overlayfs, encryptfs and fs/ioctl.c.
>> 
...
> dumps in 6.16:
> sf: ioctl: Operation not supported
>
> with the above patch:
> sf: ioctl: Inappropriate ioctl for device
>
>
> Is this expected?

This does look like an unintentional bug: As far as I can see, the
-ENOIOCTLCMD was previously used to indicate that a particular filesystem
does not have a fileattr_{get,set} callback at all, while individual
filesystems used EOPNOSUPP to indicate that a particular attribute
flag is unsupported. With the double conversion, both error codes
get turned into a single one.

     Arnd