This update eliminates a lock-order reversal warning discovered whle tracking down the system hang reported in kern/160662 and corrected in revision 225806. The LOR is not the cause of the system hang and indeed cannot cause an actual deadlock. However, it can be easily eliminated by defering the acquisition of a buflock until after all the vnode locks have been acquired.
This update eliminates a lock-order reversal warning discovered
whle tracking down the system hang reported in kern/160662 and
corrected in revision 225806. The LOR is not the cause of the system
hang and indeed cannot cause an actual deadlock. However, it can
be easily eliminated by defering the acquisition of a buflock until
after all the vnode locks have been acquired.

Reported by:     Hans Ottevanger
PR:              kern/160662

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase