DEVFS - Rollup
* Use a dynamically sized dirent structure for devfs_nodes, saving a lot
of memory.
* Fix m_* lexical space overloading issues.
* Fix issues with numerous uninitialized fields.
* Completely initialize the devfs_node before making it visible to
userland.
* Properly invalidate negative entries in the namecache when adding new
devfs nodes. Also properly recycle disconnected vnodes.
* Properly disassociate a devfs node from its vnode when freeing the
devfs node.
* Clarify device reference counts and fix a bug or two.
* Get reprobes working. Sniff writes and automatically reprobe the
whole disk or a particular slice on close() if the MBR or label area
is modified.
* Fix memory leak when mounting/umounting devfs.
Submitted-by: Alex Hornung <ahornung@gmail.com>