5 For each target there is a sequence of values (a strictly increasing
6 series of numbers) where each operation that can modify the file
7 system is assigned the next number in the series. This is the
8 transaction number, and it imposes a strict serial ordering for all
9 file system modifying operations. For file system modifying
10 requests the server assigns the next value in the sequence and
11 informs the client of the value in the 'pb_transno' field of the
12 'ptlrpc_body' of its reply to the client's request. For replys to
13 requests that do not modify the file system the 'pb_transno' field in
14 the 'ptlrpc_body' is just set to 0.