Mostly revert a5970a529c2d95271: Make files opened with O_PATH to not block non-forced unmount
Approved by: re (gjb)
(cherry picked from commit bf13db086b84c29ce901145f2800c561dcbf4d1e)
(cherry picked from commit 6daddc54debbf590cae17bead4864c7f640c07d0)