MFC r243245:

MFC r243245:

Add UFS writesuspension mechanism, designed to allow userland processes
to modify on-disk metadata for filesystems mounted for write.

Reviewed by:    kib, mckusick
Sponsored by:   FreeBSD Foundation

MFC r243247:

Add change missed in 243245.

MFC r243250:

Fix build of kdump(1).

MFC r243254:

Fix build on powerpc.

Reviewed by:    nwhitehorn

MFC r243305 by marius:

Fix build after r243245.

Submitted by:   trasz

MFC r243339 by kib:

Fix module build after r243245.

git-svn-id: svn://svn.freebsd.org/base/stable/9@246234 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f