[DLM] overlapping cancel and unlock

Full cancel and force-unlock support.  In the past, cancel and force-unlock
wouldn't work if there was another operation in progress on the lock.  Now,
both cancel and unlock-force can overlap an operation on a lock, meaning there
may be 2 or 3 operations in progress on a lock in parallel.  This support is
important not only because cancel and force-unlock are explicit operations
that an app can use, but both are used implicitly when a process exits while
holding locks.

Summary of changes:

- add-to and remove-from waiters functions were rewritten to handle situations
  with more than one remote operation outstanding on a lock

- validate_unlock_args detects when an overlapping cancel/unlock-force
  can be sent and when it needs to be delayed until a request/lookup
  reply is received

- processing request/lookup replies detects when cancel/unlock-force
  occured during the op, and carries out the delayed cancel/unlock-force

- manipulation of the "waiters" (remote operation) state of a lock moved under
  the standard rsb mutex that protects all the other lock state

- the two recovery routines related to locks on the waiters list changed
  according to the way lkb's are now locked before accessing waiters state

- waiters recovery detects when lkb's being recovered have overlapping
  cancel/unlock-force, and may not recover such locks

- revert_lock (cancel) returns a value to distinguish cases where it did
  nothing vs cases where it actually did a cancel; the cancel completion ast
  should only be done when cancel did something

- orphaned locks put on new list so they can be found later for purging

- cancel must be called on a lock when making it an orphan

- flag user locks (ENDOFLIFE) at the end of their useful life (to the
  application) so we can return an error for any further cancel/unlock-force

- we weren't setting COMP/BAST ast flags if one was already set, so we'd lose
  either a completion or blocking ast

- clear an unread bast on a lock that's become unlocked

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/dlm/dlm_internal.h

@@ -2,7 +2,7 @@
 *******************************************************************************
 **
 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
-**  Copyright (C) 2004-2005 Red Hat, Inc.  All rights reserved.
+**  Copyright (C) 2004-2007 Red Hat, Inc.  All rights reserved.
 **
 **  This copyrighted material is made available to anyone wishing to use,
 **  modify, copy, or redistribute it subject to the terms and conditions
@@ -210,6 +210,9 @@ struct dlm_args {
 #define DLM_IFL_MSTCPY		0x00010000
 #define DLM_IFL_RESEND		0x00020000
 #define DLM_IFL_DEAD		0x00040000
+#define DLM_IFL_OVERLAP_UNLOCK  0x00080000
+#define DLM_IFL_OVERLAP_CANCEL  0x00100000
+#define DLM_IFL_ENDOFLIFE	0x00200000
 #define DLM_IFL_USER		0x00000001
 #define DLM_IFL_ORPHAN		0x00000002
 
@@ -230,8 +233,8 @@ struct dlm_lkb {
 	int8_t			lkb_grmode;	/* granted lock mode */
 	int8_t			lkb_bastmode;	/* requested mode */
 	int8_t			lkb_highbast;	/* highest mode bast sent for */
-
 	int8_t			lkb_wait_type;	/* type of reply waiting for */
+	int8_t			lkb_wait_count;
 	int8_t			lkb_ast_type;	/* type of ast queued for */
 
 	struct list_head	lkb_idtbl_list;	/* lockspace lkbtbl */
@@ -440,6 +443,9 @@ struct dlm_ls {
 	struct mutex		ls_waiters_mutex;
 	struct list_head	ls_waiters;	/* lkbs needing a reply */
 
+	struct mutex		ls_orphans_mutex;
+	struct list_head	ls_orphans;
+
 	struct list_head	ls_nodes;	/* current nodes in ls */
 	struct list_head	ls_nodes_gone;	/* dead node list, recovery */
 	int			ls_num_nodes;	/* number of nodes in ls */