VOP_BWRITE(9) on FreeBSD

The text 973c3aac98f6, as FreeBSD 2.2.8-RELEASE, FreeBSD 2.2.7-RELEASE, FreeBSD 2.2.6-RELEASE, FreeBSD 2.2.5-RELEASE, FreeBSD 2.2.2-RELEASE shipped it.

write a filesystem buffer

VOP_BWRITE(9) on FreeBSD now