linux-kernel - Re: [PATCH v6 4/6] fs: make vfs_fileattr

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Message-ID: <a622643f-1585-40b0-9441-cf7ece176e83@kernel.org>
Date: Mon, 6 Oct 2025 13:09:05 +0200
From: Jiri Slaby <jirislaby@...nel.org>
To: Andrey Albershteyn <aalbersh@...hat.com>,
 Amir Goldstein <amir73il@...il.com>, Arnd Bergmann <arnd@...db.de>,
 Casey Schaufler <casey@...aufler-ca.com>,
 Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
 Pali Rohár <pali@...nel.org>,
 Paul Moore <paul@...l-moore.com>
Cc: linux-api@...r.kernel.org, linux-fsdevel@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org,
 selinux@...r.kernel.org, Andrey Albershteyn <aalbersh@...nel.org>
Subject: Re: [PATCH v6 4/6] fs: make vfs_fileattr_[get|set] return -EOPNOSUPP

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.
> 
> Signed-off-by: Andrey Albershteyn <aalbersh@...nel.org>
...
> @@ -292,6 +294,8 @@ int ioctl_setflags(struct file *file, unsigned int __user *argp)
>   			fileattr_fill_flags(&fa, flags);
>   			err = vfs_fileattr_set(idmap, dentry, &fa);
>   			mnt_drop_write_file(file);
> +			if (err == -EOPNOTSUPP)
> +				err = -ENOIOCTLCMD;

This breaks borg code (unit tests already) as it expects EOPNOTSUPP, not 
ENOIOCTLCMD/ENOTTY:
https://github.com/borgbackup/borg/blob/1c6ef7a200c7f72f8d1204d727fea32168616ceb/src/borg/platform/linux.pyx#L147

I.e. setflags now returns ENOIOCTLCMD/ENOTTY for cases where 6.16 used 
to return EOPNOTSUPP.

This minimal testcase program doing ioctl(fd2, FS_IOC_SETFLAGS, 
&FS_NODUMP_FL):
https://github.com/jirislaby/collected_sources/tree/master/ioctl_setflags

dumps in 6.16:
sf: ioctl: Operation not supported

with the above patch:
sf: ioctl: Inappropriate ioctl for device


Is this expected?

thanks,
-- 
js
suse labs