orangefs: bufmap rewrite

new waiting-for-slot logics:
	* make request for slot wait for bufmap to be set up if it
comes before it's installed *OR* while it's running down
	* make closing control device wait for all slots to be freed
	* waiting itself rewritten to (open-coded) analogues of wait_event_...
primitives - we would need wait_event_locked() and, pardon an obscenely
long name, wait_event_interruptible_exclusive_timeout_locked().
	* we never wait for more than slot_timeout_secs in total and,
if during the wait the daemon goes away, we only allow
ORANGEFS_BUFMAP_WAIT_TIMEOUT_SECS for it to come back.
	* (cosmetical) bitmap is used instead of an array of zeroes and ones
	* old (and only reached if we are about to corrupt memory) waiting
for daemon restart in service_operation() removed.

[Martin's fixes folded]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

fs/orangefs/orangefs-bufmap.h

@@ -15,10 +15,10 @@ int orangefs_bufmap_shift_query(void);
 
 int orangefs_bufmap_initialize(struct ORANGEFS_dev_map_desc *user_desc);
 
-int orangefs_get_bufmap_init(void);
-
 void orangefs_bufmap_finalize(void);
 
+void orangefs_bufmap_run_down(void);
+
 int orangefs_bufmap_get(struct orangefs_bufmap **mapp, int *buffer_index);
 
 void orangefs_bufmap_put(int buffer_index);