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[PATCH 2/2] fs: return EOPNOTSUPP from file_setattr/file_getattr syscalls

Andrey Albershteyn posted 2 patches 4 months ago
[PATCH 2/2] fs: return EOPNOTSUPP from file_setattr/file_getattr syscalls
Posted by Andrey Albershteyn 4 months ago 
These syscalls call to vfs_fileattr_get/set functions which return
ENOIOCTLCMD if filesystem doesn't support setting file attribute on an
inode. For syscalls EOPNOTSUPP would be more appropriate return error.

Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
---
 fs/file_attr.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/file_attr.c b/fs/file_attr.c
index 460b2dd21a85..5e3e2aba97b5 100644
--- a/fs/file_attr.c
+++ b/fs/file_attr.c
@@ -416,6 +416,8 @@ SYSCALL_DEFINE5(file_getattr, int, dfd, const char __user *, filename,
 	}
 
 	error = vfs_fileattr_get(filepath.dentry, &fa);
+	if (error == -ENOIOCTLCMD)
+		error = -EOPNOTSUPP;
 	if (error)
 		return error;
 
@@ -483,6 +485,8 @@ SYSCALL_DEFINE5(file_setattr, int, dfd, const char __user *, filename,
 	if (!error) {
 		error = vfs_fileattr_set(mnt_idmap(filepath.mnt),
 					 filepath.dentry, &fa);
+		if (error == -ENOIOCTLCMD)
+			error = -EOPNOTSUPP;
 		mnt_drop_write(filepath.mnt);
 	}
 

-- 
2.51.0
Re: [PATCH 2/2] fs: return EOPNOTSUPP from file_setattr/file_getattr syscalls
Posted by Darrick J. Wong 4 months ago 
On Wed, Oct 08, 2025 at 02:44:18PM +0200, Andrey Albershteyn wrote:
> These syscalls call to vfs_fileattr_get/set functions which return
> ENOIOCTLCMD if filesystem doesn't support setting file attribute on an
> inode. For syscalls EOPNOTSUPP would be more appropriate return error.
> 
> Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
> ---
>  fs/file_attr.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/file_attr.c b/fs/file_attr.c
> index 460b2dd21a85..5e3e2aba97b5 100644
> --- a/fs/file_attr.c
> +++ b/fs/file_attr.c
> @@ -416,6 +416,8 @@ SYSCALL_DEFINE5(file_getattr, int, dfd, const char __user *, filename,
>  	}
>  
>  	error = vfs_fileattr_get(filepath.dentry, &fa);
> +	if (error == -ENOIOCTLCMD)

Hrm.  Back in 6.17, XFS would return ENOTTY if you called ->fileattr_get
on a special file:

int
xfs_fileattr_get(
	struct dentry		*dentry,
	struct file_kattr	*fa)
{
	struct xfs_inode	*ip = XFS_I(d_inode(dentry));

	if (d_is_special(dentry))
		return -ENOTTY;
	...
}

Given that there are other fileattr_[gs]et implementations out there
that might return ENOTTY (e.g. fuse servers and other externally
maintained filesystems), I think both syscall functions need to check
for that as well:

	if (error == -ENOIOCTLCMD || error == -ENOTTY)
		return -EOPNOTSUPP;

--D

> +		error = -EOPNOTSUPP;
>  	if (error)
>  		return error;
>  
> @@ -483,6 +485,8 @@ SYSCALL_DEFINE5(file_setattr, int, dfd, const char __user *, filename,
>  	if (!error) {
>  		error = vfs_fileattr_set(mnt_idmap(filepath.mnt),
>  					 filepath.dentry, &fa);
> +		if (error == -ENOIOCTLCMD)
> +			error = -EOPNOTSUPP;
>  		mnt_drop_write(filepath.mnt);
>  	}
>  
> 
> -- 
> 2.51.0
> 
>
Re: [PATCH 2/2] fs: return EOPNOTSUPP from file_setattr/file_getattr syscalls
Posted by Andrey Albershteyn 4 months ago 
On 2025-10-09 10:20:41, Darrick J. Wong wrote:
> On Wed, Oct 08, 2025 at 02:44:18PM +0200, Andrey Albershteyn wrote:
> > These syscalls call to vfs_fileattr_get/set functions which return
> > ENOIOCTLCMD if filesystem doesn't support setting file attribute on an
> > inode. For syscalls EOPNOTSUPP would be more appropriate return error.
> > 
> > Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
> > ---
> >  fs/file_attr.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/fs/file_attr.c b/fs/file_attr.c
> > index 460b2dd21a85..5e3e2aba97b5 100644
> > --- a/fs/file_attr.c
> > +++ b/fs/file_attr.c
> > @@ -416,6 +416,8 @@ SYSCALL_DEFINE5(file_getattr, int, dfd, const char __user *, filename,
> >  	}
> >  
> >  	error = vfs_fileattr_get(filepath.dentry, &fa);
> > +	if (error == -ENOIOCTLCMD)
> 
> Hrm.  Back in 6.17, XFS would return ENOTTY if you called ->fileattr_get
> on a special file:
> 
> int
> xfs_fileattr_get(
> 	struct dentry		*dentry,
> 	struct file_kattr	*fa)
> {
> 	struct xfs_inode	*ip = XFS_I(d_inode(dentry));
> 
> 	if (d_is_special(dentry))
> 		return -ENOTTY;
> 	...
> }
> 
> Given that there are other fileattr_[gs]et implementations out there
> that might return ENOTTY (e.g. fuse servers and other externally
> maintained filesystems), I think both syscall functions need to check
> for that as well:
> 
> 	if (error == -ENOIOCTLCMD || error == -ENOTTY)
> 		return -EOPNOTSUPP;

Make sense (looks like ubifs, jfs and gfs2 also return ENOTTY for
special files), I haven't found ENOTTY being used for anything else
there

-- 
- Andrey
Re: [PATCH 2/2] fs: return EOPNOTSUPP from file_setattr/file_getattr syscalls
Posted by Christian Brauner 4 months ago 
On Fri, Oct 10, 2025 at 12:05:04PM +0200, Andrey Albershteyn wrote:
> On 2025-10-09 10:20:41, Darrick J. Wong wrote:
> > On Wed, Oct 08, 2025 at 02:44:18PM +0200, Andrey Albershteyn wrote:
> > > These syscalls call to vfs_fileattr_get/set functions which return
> > > ENOIOCTLCMD if filesystem doesn't support setting file attribute on an
> > > inode. For syscalls EOPNOTSUPP would be more appropriate return error.
> > > 
> > > Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
> > > ---
> > >  fs/file_attr.c | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > > 
> > > diff --git a/fs/file_attr.c b/fs/file_attr.c
> > > index 460b2dd21a85..5e3e2aba97b5 100644
> > > --- a/fs/file_attr.c
> > > +++ b/fs/file_attr.c
> > > @@ -416,6 +416,8 @@ SYSCALL_DEFINE5(file_getattr, int, dfd, const char __user *, filename,
> > >  	}
> > >  
> > >  	error = vfs_fileattr_get(filepath.dentry, &fa);
> > > +	if (error == -ENOIOCTLCMD)
> > 
> > Hrm.  Back in 6.17, XFS would return ENOTTY if you called ->fileattr_get
> > on a special file:
> > 
> > int
> > xfs_fileattr_get(
> > 	struct dentry		*dentry,
> > 	struct file_kattr	*fa)
> > {
> > 	struct xfs_inode	*ip = XFS_I(d_inode(dentry));
> > 
> > 	if (d_is_special(dentry))
> > 		return -ENOTTY;
> > 	...
> > }
> > 
> > Given that there are other fileattr_[gs]et implementations out there
> > that might return ENOTTY (e.g. fuse servers and other externally
> > maintained filesystems), I think both syscall functions need to check
> > for that as well:
> > 
> > 	if (error == -ENOIOCTLCMD || error == -ENOTTY)
> > 		return -EOPNOTSUPP;
> 
> Make sense (looks like ubifs, jfs and gfs2 also return ENOTTY for
> special files), I haven't found ENOTTY being used for anything else
> there

I'm folding this in.
Re: [PATCH 2/2] fs: return EOPNOTSUPP from file_setattr/file_getattr syscalls
Posted by Jan Kara 4 months ago 
On Wed 08-10-25 14:44:18, Andrey Albershteyn wrote:
> These syscalls call to vfs_fileattr_get/set functions which return
> ENOIOCTLCMD if filesystem doesn't support setting file attribute on an
> inode. For syscalls EOPNOTSUPP would be more appropriate return error.
> 
> Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/file_attr.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/file_attr.c b/fs/file_attr.c
> index 460b2dd21a85..5e3e2aba97b5 100644
> --- a/fs/file_attr.c
> +++ b/fs/file_attr.c
> @@ -416,6 +416,8 @@ SYSCALL_DEFINE5(file_getattr, int, dfd, const char __user *, filename,
>  	}
>  
>  	error = vfs_fileattr_get(filepath.dentry, &fa);
> +	if (error == -ENOIOCTLCMD)
> +		error = -EOPNOTSUPP;
>  	if (error)
>  		return error;
>  
> @@ -483,6 +485,8 @@ SYSCALL_DEFINE5(file_setattr, int, dfd, const char __user *, filename,
>  	if (!error) {
>  		error = vfs_fileattr_set(mnt_idmap(filepath.mnt),
>  					 filepath.dentry, &fa);
> +		if (error == -ENOIOCTLCMD)
> +			error = -EOPNOTSUPP;
>  		mnt_drop_write(filepath.mnt);
>  	}
>  
> 
> -- 
> 2.51.0
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR
Re: [PATCH 2/2] fs: return EOPNOTSUPP from file_setattr/file_getattr syscalls
Posted by Arnd Bergmann 4 months ago 
On Wed, Oct 8, 2025, at 14:44, Andrey Albershteyn wrote:
> These syscalls call to vfs_fileattr_get/set functions which return
> ENOIOCTLCMD if filesystem doesn't support setting file attribute on an
> inode. For syscalls EOPNOTSUPP would be more appropriate return error.
>
> Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>

Reviewed-by: Arnd Bergmann <arnd@arndb.de>

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