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

This reverts commit 474b155adf3927d2c944423045757b54aa1ca4de.

This patch caused regression in ioctl_setflags(). Underlying filesystems
use EOPNOTSUPP to indicate that flag is not supported. This error is
also gets converted in ioctl_setflags(). Therefore, for unsupported
flags error changed from EOPNOSUPP to ENOIOCTLCMD.

Link: https://lore.kernel.org/linux-xfs/[e-mail]/
Signed-off-by: Andrey Albershteyn <[e-mail]>
Signed-off-by: Christian Brauner <[e-mail]>

fs/file_attr.c

···
 	int error;
 
 	if (!inode->i_op->fileattr_get)
-		return -EOPNOTSUPP;
+		return -ENOIOCTLCMD;
 
 	error = security_inode_file_getattr(dentry, fa);
 	if (error)
···
 	int err;
 
 	if (!inode->i_op->fileattr_set)
-		return -EOPNOTSUPP;
+		return -ENOIOCTLCMD;
 
 	if (!inode_owner_or_capable(idmap, inode))
 		return -EPERM;
···
 	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;
···
 			fileattr_fill_flags(&fa, flags);
 			err = vfs_fileattr_set(idmap, dentry, &fa);
 			mnt_drop_write_file(file);
-			if (err == -EOPNOTSUPP)
-				err = -ENOIOCTLCMD;
 		}
 	}
 	return err;
···
 	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);
 
···
 		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

···
 cleanup:
 	fuse_priv_ioctl_cleanup(inode, ff);
 
-	if (err == -ENOTTY)
-		err = -EOPNOTSUPP;
 	return err;
 }
 
···
 cleanup:
 	fuse_priv_ioctl_cleanup(inode, ff);
 
-	if (err == -ENOTTY)
-		err = -EOPNOTSUPP;
 	return err;
 }

fs/overlayfs/copy_up.c

···
 	err = ovl_real_fileattr_get(old, &oldfa);
 	if (err) {
 		/* Ntfs-3g returns -EINVAL for "no fileattr support" */
-		if (err == -EOPNOTSUPP || err == -EINVAL)
+		if (err == -ENOTTY || err == -EINVAL)
 			return 0;
 		pr_warn("failed to retrieve lower fileattr (%pd2, err=%i)\n",
 			old->dentry, err);

fs/overlayfs/inode.c

···
 	if (err)
 		return err;
 
-	return vfs_fileattr_get(realpath->dentry, fa);
+	err = vfs_fileattr_get(realpath->dentry, fa);
+	if (err == -ENOIOCTLCMD)
+		err = -ENOTTY;
+	return err;
 }
 
 int ovl_fileattr_get(struct dentry *dentry, struct file_kattr *fa)