fileSync

fn fileSync(userdata: ?*anyopaque, file: File) File.SyncError!void {
    const ev: *Evented = @ptrCast(@alignCast(userdata));
    var cancel_region: CancelRegion = .init();
    defer cancel_region.deinit();
    while (true) {
        const thread = try cancel_region.awaitIoUring();
        thread.enqueue().* = .{
            .opcode = .FSYNC,
            .flags = 0,
            .ioprio = 0,
            .fd = file.handle,
            .off = 0,
            .addr = 0,
            .len = 0,
            .rw_flags = 0,
            .user_data = @intFromPtr(cancel_region.fiber),
            .buf_index = 0,
            .personality = 0,
            .splice_fd_in = 0,
            .addr3 = 0,
            .resv = 0,
        };
        ev.yield(null, .nothing);
        switch (cancel_region.errno()) {
            .SUCCESS => return,
            .INTR, .CANCELED => {},
            .BADF => |err| return errnoBug(err),
            .INVAL => |err| return errnoBug(err),
            .ROFS => |err| return errnoBug(err),
            .IO => return error.InputOutput,
            .NOSPC => return error.NoSpaceLeft,
            .DQUOT => return error.DiskQuota,
            else => |err| return unexpectedErrno(err),
        }
    }
}