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

Jan Kara
2025-07-01T12:51:58Z

On Tue 01-07-25 08:05:45, Amir Goldstein wrote:
> On Mon, Jun 30, 2025 at 6:20 PM Andrey Albershteyn <aalbersh@redhat.com> 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@kernel.org>
...
> > --- a/fs/overlayfs/inode.c
> > +++ b/fs/overlayfs/inode.c
> > @@ -721,7 +721,7 @@ int ovl_real_fileattr_get(const struct path *realpath, struct fileattr *fa)
> > return err;
> >
> > err = vfs_fileattr_get(realpath->dentry, fa);
> > - if (err == -ENOIOCTLCMD)
> > + if (err == -EOPNOTSUPP)
> > err = -ENOTTY;
> > return err;
> > }
>
> That's the wrong way, because it hides the desired -EOPNOTSUPP
> return code from ovl_fileattr_get().
>
> The conversion to -ENOTTY was done for
> 5b0a414d06c3 ("ovl: fix filattr copy-up failure"),
> so please do this instead:
>
> --- a/fs/overlayfs/inode.c
> +++ b/fs/overlayfs/inode.c
> @@ -722,7 +722,7 @@ int ovl_real_fileattr_get(const struct path
> *realpath, struct fileattr *fa)
>
> err = vfs_fileattr_get(realpath->dentry, fa);
> if (err == -ENOIOCTLCMD)
> - err = -ENOTTY;
> + err = -EOPNOTSUPP;

Is this really needed? AFAICS nobody returns ENOIOCTLCMD after this
patch...

Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR