tree cb2bc18c6c0e09e2af7f5bbc3ad007acc77c8ebf
parent c0ef65d2928249e822b813beb41b6c1478c556ab
author Al Viro <viro@zeniv.linux.org.uk> 1497728646 -0400
committer Al Viro <viro@zeniv.linux.org.uk> 1497734562 -0400

ufs: fix the logics for tail relocation

* original hysteresis loop got broken by typo back in 2002; now
it never switches out of OPTTIME state.  Fixed.
* critical levels for switching from OPTTIME to OPTSPACE and back
ought to be calculated once, at mount time.
* we should use mul_u64_u32_div() for those calculations, now that
->s_dsize is 64bit.
* to quote Kirk McKusick (in 1995 FreeBSD commit message):
    The threshold for switching from time-space and space-time is too small
    when minfree is 5%...so make it stay at space in this case.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>