dlm: remove shared message stub for recovery

kmalloc a stub message struct during recovery instead of sharing the
struct in the lockspace.  This leaves the lockspace stub_ms only for
faking downconvert replies, where it is never modified and sharing
is not a problem.

Also improve the debug messages in the same recovery function.

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

fs/dlm/dlm_internal.h

@@ -209,6 +209,7 @@ struct dlm_args {
 #define DLM_IFL_WATCH_TIMEWARN	0x00400000
 #define DLM_IFL_TIMEOUT_CANCEL	0x00800000
 #define DLM_IFL_DEADLOCK_CANCEL	0x01000000
+#define DLM_IFL_STUB_MS		0x02000000 /* magic number for m_flags */
 #define DLM_IFL_USER		0x00000001
 #define DLM_IFL_ORPHAN		0x00000002
 

fs/dlm/lock.c

@@ -1037,10 +1037,10 @@ static int remove_from_waiters_ms(struct dlm_lkb *lkb, struct dlm_message *ms)
 	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
 	int error;
 
-	if (ms != &ls->ls_stub_ms)
+	if (ms->m_flags != DLM_IFL_STUB_MS)
 		mutex_lock(&ls->ls_waiters_mutex);
 	error = _remove_from_waiters(lkb, ms->m_type, ms);
-	if (ms != &ls->ls_stub_ms)
+	if (ms->m_flags != DLM_IFL_STUB_MS)
 		mutex_unlock(&ls->ls_waiters_mutex);
 	return error;
 }
@@ -1462,14 +1462,8 @@ static void grant_lock_pending(struct dlm_rsb *r, struct dlm_lkb *lkb)
    ALTPR/ALTCW: our rqmode may have been changed to PR or CW to become
    compatible with other granted locks */
 
-static void munge_demoted(struct dlm_lkb *lkb, struct dlm_message *ms)
+static void munge_demoted(struct dlm_lkb *lkb)
 {
-	if (ms->m_type != DLM_MSG_CONVERT_REPLY) {
-		log_print("munge_demoted %x invalid reply type %d",
-			  lkb->lkb_id, ms->m_type);
-		return;
-	}
-
 	if (lkb->lkb_rqmode == DLM_LOCK_IV || lkb->lkb_grmode == DLM_LOCK_IV) {
 		log_print("munge_demoted %x invalid modes gr %d rq %d",
 			  lkb->lkb_id, lkb->lkb_grmode, lkb->lkb_rqmode);
@@ -2966,9 +2960,9 @@ static int send_convert(struct dlm_rsb *r, struct dlm_lkb *lkb)
 	/* down conversions go without a reply from the master */
 	if (!error && down_conversion(lkb)) {
 		remove_from_waiters(lkb, DLM_MSG_CONVERT_REPLY);
+		r->res_ls->ls_stub_ms.m_flags = DLM_IFL_STUB_MS;
 		r->res_ls->ls_stub_ms.m_type = DLM_MSG_CONVERT_REPLY;
 		r->res_ls->ls_stub_ms.m_result = 0;
-		r->res_ls->ls_stub_ms.m_flags = lkb->lkb_flags;
 		__receive_convert_reply(r, lkb, &r->res_ls->ls_stub_ms);
 	}
 
@@ -3156,6 +3150,9 @@ static void receive_flags(struct dlm_lkb *lkb, struct dlm_message *ms)
 
 static void receive_flags_reply(struct dlm_lkb *lkb, struct dlm_message *ms)
 {
+	if (ms->m_flags == DLM_IFL_STUB_MS)
+		return;
+
 	lkb->lkb_sbflags = ms->m_sbflags;
 	lkb->lkb_flags = (lkb->lkb_flags & 0xFFFF0000) |
 		         (ms->m_flags & 0x0000FFFF);
@@ -3698,7 +3695,7 @@ static void __receive_convert_reply(struct dlm_rsb *r, struct dlm_lkb *lkb,
 		/* convert was queued on remote master */
 		receive_flags_reply(lkb, ms);
 		if (is_demoted(lkb))
-			munge_demoted(lkb, ms);
+			munge_demoted(lkb);
 		del_lkb(r, lkb);
 		add_lkb(r, lkb, DLM_LKSTS_CONVERT);
 		add_timeout(lkb);
@@ -3708,7 +3705,7 @@ static void __receive_convert_reply(struct dlm_rsb *r, struct dlm_lkb *lkb,
 		/* convert was granted on remote master */
 		receive_flags_reply(lkb, ms);
 		if (is_demoted(lkb))
-			munge_demoted(lkb, ms);
+			munge_demoted(lkb);
 		grant_lock_pc(r, lkb, ms);
 		queue_cast(r, lkb, 0);
 		break;
@@ -4082,15 +4079,17 @@ void dlm_receive_buffer(union dlm_packet *p, int nodeid)
 	dlm_put_lockspace(ls);
 }
 
-static void recover_convert_waiter(struct dlm_ls *ls, struct dlm_lkb *lkb)
+static void recover_convert_waiter(struct dlm_ls *ls, struct dlm_lkb *lkb,
+				   struct dlm_message *ms_stub)
 {
 	if (middle_conversion(lkb)) {
 		hold_lkb(lkb);
-		ls->ls_stub_ms.m_type = DLM_MSG_CONVERT_REPLY;
-		ls->ls_stub_ms.m_result = -EINPROGRESS;
-		ls->ls_stub_ms.m_flags = lkb->lkb_flags;
-		ls->ls_stub_ms.m_header.h_nodeid = lkb->lkb_nodeid;
-		_receive_convert_reply(lkb, &ls->ls_stub_ms);
+		memset(ms_stub, 0, sizeof(struct dlm_message));
+		ms_stub->m_flags = DLM_IFL_STUB_MS;
+		ms_stub->m_type = DLM_MSG_CONVERT_REPLY;
+		ms_stub->m_result = -EINPROGRESS;
+		ms_stub->m_header.h_nodeid = lkb->lkb_nodeid;
+		_receive_convert_reply(lkb, ms_stub);
 
 		/* Same special case as in receive_rcom_lock_args() */
 		lkb->lkb_grmode = DLM_LOCK_IV;
@@ -4131,13 +4130,27 @@ static int waiter_needs_recovery(struct dlm_ls *ls, struct dlm_lkb *lkb)
 void dlm_recover_waiters_pre(struct dlm_ls *ls)
 {
 	struct dlm_lkb *lkb, *safe;
+	struct dlm_message *ms_stub;
 	int wait_type, stub_unlock_result, stub_cancel_result;
 
+	ms_stub = kmalloc(GFP_KERNEL, sizeof(struct dlm_message));
+	if (!ms_stub) {
+		log_error(ls, "dlm_recover_waiters_pre no mem");
+		return;
+	}
+
 	mutex_lock(&ls->ls_waiters_mutex);
 
 	list_for_each_entry_safe(lkb, safe, &ls->ls_waiters, lkb_wait_reply) {
-		log_debug(ls, "pre recover waiter lkid %x type %d flags %x",
-			  lkb->lkb_id, lkb->lkb_wait_type, lkb->lkb_flags);
+
+		/* exclude debug messages about unlocks because there can be so
+		   many and they aren't very interesting */
+
+		if (lkb->lkb_wait_type != DLM_MSG_UNLOCK) {
+			log_debug(ls, "recover_waiter %x nodeid %d "
+				  "msg %d to %d", lkb->lkb_id, lkb->lkb_nodeid,
+				  lkb->lkb_wait_type, lkb->lkb_wait_nodeid);
+		}
 
 		/* all outstanding lookups, regardless of destination  will be
 		   resent after recovery is done */
@@ -4183,26 +4196,28 @@ void dlm_recover_waiters_pre(struct dlm_ls *ls)
 			break;
 
 		case DLM_MSG_CONVERT:
-			recover_convert_waiter(ls, lkb);
+			recover_convert_waiter(ls, lkb, ms_stub);
 			break;
 
 		case DLM_MSG_UNLOCK:
 			hold_lkb(lkb);
-			ls->ls_stub_ms.m_type = DLM_MSG_UNLOCK_REPLY;
-			ls->ls_stub_ms.m_result = stub_unlock_result;
-			ls->ls_stub_ms.m_flags = lkb->lkb_flags;
-			ls->ls_stub_ms.m_header.h_nodeid = lkb->lkb_nodeid;
-			_receive_unlock_reply(lkb, &ls->ls_stub_ms);
+			memset(ms_stub, 0, sizeof(struct dlm_message));
+			ms_stub->m_flags = DLM_IFL_STUB_MS;
+			ms_stub->m_type = DLM_MSG_UNLOCK_REPLY;
+			ms_stub->m_result = stub_unlock_result;
+			ms_stub->m_header.h_nodeid = lkb->lkb_nodeid;
+			_receive_unlock_reply(lkb, ms_stub);
 			dlm_put_lkb(lkb);
 			break;
 
 		case DLM_MSG_CANCEL:
 			hold_lkb(lkb);
-			ls->ls_stub_ms.m_type = DLM_MSG_CANCEL_REPLY;
-			ls->ls_stub_ms.m_result = stub_cancel_result;
-			ls->ls_stub_ms.m_flags = lkb->lkb_flags;
-			ls->ls_stub_ms.m_header.h_nodeid = lkb->lkb_nodeid;
-			_receive_cancel_reply(lkb, &ls->ls_stub_ms);
+			memset(ms_stub, 0, sizeof(struct dlm_message));
+			ms_stub->m_flags = DLM_IFL_STUB_MS;
+			ms_stub->m_type = DLM_MSG_CANCEL_REPLY;
+			ms_stub->m_result = stub_cancel_result;
+			ms_stub->m_header.h_nodeid = lkb->lkb_nodeid;
+			_receive_cancel_reply(lkb, ms_stub);
 			dlm_put_lkb(lkb);
 			break;
 
@@ -4213,6 +4228,7 @@ void dlm_recover_waiters_pre(struct dlm_ls *ls)
 		schedule();
 	}
 	mutex_unlock(&ls->ls_waiters_mutex);
+	kfree(ms_stub);
 }
 
 static struct dlm_lkb *find_resend_waiter(struct dlm_ls *ls)
@@ -4277,8 +4293,8 @@ int dlm_recover_waiters_post(struct dlm_ls *ls)
 		ou = is_overlap_unlock(lkb);
 		err = 0;
 
-		log_debug(ls, "recover_waiters_post %x type %d flags %x %s",
-			  lkb->lkb_id, mstype, lkb->lkb_flags, r->res_name);
+		log_debug(ls, "recover_waiter %x nodeid %d msg %d r_nodeid %d",
+			  lkb->lkb_id, lkb->lkb_nodeid, mstype, r->res_nodeid);
 
 		/* At this point we assume that we won't get a reply to any
 		   previous op or overlap op on this lock.  First, do a big