MFC r211213:

MFC r211213:
The buffers b_vflags field is not always properly protected by
bufobj lock. If b_bufobj is not NULL, then bufobj lock should be
held when manipulating the flags. Not doing this sometimes leaves
BV_BKGRDINPROG to be erronously set, causing softdep' getdirtybuf() to
stuck indefinitely in "getbuf" sleep, waiting for background write to
finish which is not actually performed.

Add BO_LOCK() in the cases where it was missed.

git-svn-id: svn://svn.freebsd.org/base/stable/8@212583 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f