fs: make vfs_fileattr_[get|set] return -EOPNOTSUPP

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>
Link: https://lore.kernel.org/20250630-xattrat-syscall-v6-4-c4e3bc35227b@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: alberand

fs/file_attr.c

@@ -80,7 +80,7 @@ int vfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
 	int error;
 
 	if (!inode->i_op->fileattr_get)
-		return -ENOIOCTLCMD;
+		return -EOPNOTSUPP;
 
 	error = security_inode_file_getattr(dentry, fa);
 	if (error)
@@ -230,7 +230,7 @@ int vfs_fileattr_set(struct mnt_idmap *idmap, struct dentry *dentry,
 	int err;
 
 	if (!inode->i_op->fileattr_set)
-		return -ENOIOCTLCMD;
+		return -EOPNOTSUPP;
 
 	if (!inode_owner_or_capable(idmap, inode))
 		return -EPERM;
@@ -272,6 +272,8 @@ int ioctl_getflags(struct file *file, unsigned int __user *argp)
 	int err;
 
 	err = vfs_fileattr_get(file->f_path.dentry, &fa);
+	if (err == -EOPNOTSUPP)
+		err = -ENOIOCTLCMD;
 	if (!err)
 		err = put_user(fa.flags, argp);
 	return err;
@@ -293,6 +295,8 @@ 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;
 		}
 	}
 	return err;
@@ -305,6 +309,8 @@ int ioctl_fsgetxattr(struct file *file, void __user *argp)
 	int err;
 
 	err = vfs_fileattr_get(file->f_path.dentry, &fa);
+	if (err == -EOPNOTSUPP)
+		err = -ENOIOCTLCMD;
 	if (!err)
 		err = copy_fsxattr_to_user(&fa, argp);
 
@@ -325,6 +331,8 @@ int ioctl_fssetxattr(struct file *file, void __user *argp)
 		if (!err) {
 			err = vfs_fileattr_set(idmap, dentry, &fa);
 			mnt_drop_write_file(file);
+			if (err == -EOPNOTSUPP)
+				err = -ENOIOCTLCMD;
 		}
 	}
 	return err;

fs/fuse/ioctl.c

@@ -536,6 +536,8 @@ int fuse_fileattr_get(struct dentry *dentry, struct fileattr *fa)
 cleanup:
 	fuse_priv_ioctl_cleanup(inode, ff);
 
+	if (err == -ENOTTY)
+		err = -EOPNOTSUPP;
 	return err;
 }
 
@@ -572,5 +574,7 @@ int fuse_fileattr_set(struct mnt_idmap *idmap,
 cleanup:
 	fuse_priv_ioctl_cleanup(inode, ff);
 
+	if (err == -ENOTTY)
+		err = -EOPNOTSUPP;
 	return err;
 }

fs/overlayfs/copy_up.c

@@ -178,7 +178,7 @@ static int ovl_copy_fileattr(struct inode *inode, const struct path *old,
 	err = ovl_real_fileattr_get(old, &oldfa);
 	if (err) {
 		/* Ntfs-3g returns -EINVAL for "no fileattr support" */
-		if (err == -ENOTTY || err == -EINVAL)
+		if (err == -EOPNOTSUPP || err == -EINVAL)
 			return 0;
 		pr_warn("failed to retrieve lower fileattr (%pd2, err=%i)\n",
 			old->dentry, err);

fs/overlayfs/inode.c

@@ -720,10 +720,7 @@ int ovl_real_fileattr_get(const struct path *realpath, struct fileattr *fa)
 	if (err)
 		return err;
 
-	err = vfs_fileattr_get(realpath->dentry, fa);
-	if (err == -ENOIOCTLCMD)
-		err = -ENOTTY;
-	return err;
+	return vfs_fileattr_get(realpath->dentry, fa);
 }
 
 int ovl_fileattr_get(struct dentry *dentry, struct fileattr *fa)