Re: NFS locking bug -- limited mtime resolution means nfs_lock() does not provide coherency guarantee

[Trond Myklebust]

>>>>> " " == Albert D Cahalan <[EMAIL PROTECTED]> writes:

     > It would not be reasonable to try extending ext2 to 64-bit
     > times, but milliseconds might be doable. You'd need 4 bytes to
     > support the 3 standard time stamps.

     > Going to microseconds would require 8 free bytes, which I don't
     > think we have. (but we do have more that one might think, due
     > to the unimplemented junk)

Don't forget that 2^20 > 10^6, hence if you really want units of
microseconds, you actually only need to save 3 bytes worth of data per
timestamp.

For the purposes of NFS, however the 'microseconds' field doesn't
actually have to mean anything. It's just used as a cookie.
Furthermore, only the mtime field, and to a limited extent the ctime
field, are used for attribute consistency checking.

If NFS was the only concern therefore, you would get far on just
saving one extra 24-bit field.

Cheers,
  Trond
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