Konstantin Belousov 5ffc99e2e4 Handle races when remounting UFS volume from ro to rw.
In particular, ensure that writers are not unleashed before SU
structures are initialized.  Also, correctly handle MNT_ASYNC before
this.

Reported and tested by:	pho
Reviewed by:	mckusick
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2019-04-08 15:20:05 +00:00
..