1 files changed, 55 insertions, 14 deletions

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index b455919..2082daf 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -1670,9 +1670,10 @@ static int can_be_granted(struct dlm_rsb *r, struct dlm_lkb *lkb, int now,
    with a deadlk here, we'd have to generate something like grant_lock with
    the deadlk error.) */
 
-/* returns the highest requested mode of all blocked conversions */
+/* Returns the highest requested mode of all blocked conversions; sets
+   cw if there's a blocked conversion to DLM_LOCK_CW. */
 
-static int grant_pending_convert(struct dlm_rsb *r, int high)
+static int grant_pending_convert(struct dlm_rsb *r, int high, int *cw)
 {
 	struct dlm_lkb *lkb, *s;
 	int hi, demoted, quit, grant_restart, demote_restart;
@@ -1709,6 +1710,9 @@ static int grant_pending_convert(struct dlm_rsb *r, int high)
 		}
 
 		hi = max_t(int, lkb->lkb_rqmode, hi);
+
+		if (cw && lkb->lkb_rqmode == DLM_LOCK_CW)
+			*cw = 1;
 	}
 
 	if (grant_restart)
@@ -1721,29 +1725,52 @@ static int grant_pending_convert(struct dlm_rsb *r, int high)
 	return max_t(int, high, hi);
 }
 
-static int grant_pending_wait(struct dlm_rsb *r, int high)
+static int grant_pending_wait(struct dlm_rsb *r, int high, int *cw)
 {
 	struct dlm_lkb *lkb, *s;
 
 	list_for_each_entry_safe(lkb, s, &r->res_waitqueue, lkb_statequeue) {
 		if (can_be_granted(r, lkb, 0, NULL))
 			grant_lock_pending(r, lkb);
-                else
+                else {
 			high = max_t(int, lkb->lkb_rqmode, high);
+			if (lkb->lkb_rqmode == DLM_LOCK_CW)
+				*cw = 1;
+		}
 	}
 
 	return high;
 }
 
+/* cw of 1 means there's a lock with a rqmode of DLM_LOCK_CW that's blocked
+   on either the convert or waiting queue.
+   high is the largest rqmode of all locks blocked on the convert or
+   waiting queue. */
+
+static int lock_requires_bast(struct dlm_lkb *gr, int high, int cw)
+{
+	if (gr->lkb_grmode == DLM_LOCK_PR && cw) {
+		if (gr->lkb_highbast < DLM_LOCK_EX)
+			return 1;
+		return 0;
+	}
+
+	if (gr->lkb_highbast < high &&
+	    !__dlm_compat_matrix[gr->lkb_grmode+1][high+1])
+		return 1;
+	return 0;
+}
+
 static void grant_pending_locks(struct dlm_rsb *r)
 {
 	struct dlm_lkb *lkb, *s;
 	int high = DLM_LOCK_IV;
+	int cw = 0;
 
 	DLM_ASSERT(is_master(r), dlm_dump_rsb(r););
 
-	high = grant_pending_convert(r, high);
-	high = grant_pending_wait(r, high);
+	high = grant_pending_convert(r, high, &cw);
+	high = grant_pending_wait(r, high, &cw);
 
 	if (high == DLM_LOCK_IV)
 		return;
@@ -1751,27 +1778,41 @@ static void grant_pending_locks(struct dlm_rsb *r)
 	/*
 	 * If there are locks left on the wait/convert queue then send blocking
 	 * ASTs to granted locks based on the largest requested mode (high)
-	 * found above. FIXME: highbast < high comparison not valid for PR/CW.
+	 * found above.
 	 */
 
 	list_for_each_entry_safe(lkb, s, &r->res_grantqueue, lkb_statequeue) {
-		if (lkb->lkb_bastaddr && (lkb->lkb_highbast < high) &&
-		    !__dlm_compat_matrix[lkb->lkb_grmode+1][high+1]) {
-			queue_bast(r, lkb, high);
+		if (lkb->lkb_bastaddr && lock_requires_bast(lkb, high, cw)) {
+			if (cw && high == DLM_LOCK_PR)
+				queue_bast(r, lkb, DLM_LOCK_CW);
+			else
+				queue_bast(r, lkb, high);
 			lkb->lkb_highbast = high;
 		}
 	}
 }
 
+static int modes_require_bast(struct dlm_lkb *gr, struct dlm_lkb *rq)
+{
+	if ((gr->lkb_grmode == DLM_LOCK_PR && rq->lkb_rqmode == DLM_LOCK_CW) ||
+	    (gr->lkb_grmode == DLM_LOCK_CW && rq->lkb_rqmode == DLM_LOCK_PR)) {
+		if (gr->lkb_highbast < DLM_LOCK_EX)
+			return 1;
+		return 0;
+	}
+
+	if (gr->lkb_highbast < rq->lkb_rqmode && !modes_compat(gr, rq))
+		return 1;
+	return 0;
+}
+
 static void send_bast_queue(struct dlm_rsb *r, struct list_head *head,
 			    struct dlm_lkb *lkb)
 {
 	struct dlm_lkb *gr;
 
 	list_for_each_entry(gr, head, lkb_statequeue) {
-		if (gr->lkb_bastaddr &&
-		    gr->lkb_highbast < lkb->lkb_rqmode &&
-		    !modes_compat(gr, lkb)) {
+		if (gr->lkb_bastaddr && modes_require_bast(gr, lkb)) {
 			queue_bast(r, gr, lkb->lkb_rqmode);
 			gr->lkb_highbast = lkb->lkb_rqmode;
 		}
@@ -2235,7 +2276,7 @@ static int do_convert(struct dlm_rsb *r, struct dlm_lkb *lkb)
 	   before we try again to grant this one. */
 
 	if (is_demoted(lkb)) {
-		grant_pending_convert(r, DLM_LOCK_IV);
+		grant_pending_convert(r, DLM_LOCK_IV, NULL);
 		if (_can_be_granted(r, lkb, 1)) {
 			grant_lock(r, lkb);
 			queue_cast(r, lkb, 0);