gfs2: Free quota data objects synchronously

In gfs2_quota_cleanup(), wait for the quota data objects to be freed
before returning.  Otherwise, there is no guarantee that the quota data
objects will be gone when their kmem cache is destroyed.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/quota.c

@@ -109,7 +109,11 @@ static inline void spin_unlock_bucket(unsigned int hash)
 static void gfs2_qd_dealloc(struct rcu_head *rcu)
 {
 	struct gfs2_quota_data *qd = container_of(rcu, struct gfs2_quota_data, qd_rcu);
+	struct gfs2_sbd *sdp = qd->qd_sbd;
+
 	kmem_cache_free(gfs2_quotad_cachep, qd);
+	if (atomic_dec_and_test(&sdp->sd_quota_count))
+		wake_up(&sdp->sd_kill_wait);
 }
 
 static void gfs2_qd_dispose(struct gfs2_quota_data *qd)
@@ -143,7 +147,6 @@ static void gfs2_qd_list_dispose(struct list_head *list)
 		list_del(&qd->qd_lru);
 
 		gfs2_qd_dispose(qd);
-		atomic_dec(&sdp->sd_quota_count);
 	}
 }
 
@@ -317,13 +320,24 @@ static void qd_hold(struct gfs2_quota_data *qd)
 
 static void qd_put(struct gfs2_quota_data *qd)
 {
+	struct gfs2_sbd *sdp;
+
 	if (lockref_put_or_lock(&qd->qd_lockref))
 		return;
 
+	BUG_ON(__lockref_is_dead(&qd->qd_lockref));
+	sdp = qd->qd_sbd;
+	if (unlikely(!test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))) {
+		lockref_mark_dead(&qd->qd_lockref);
+		spin_unlock(&qd->qd_lockref.lock);
+
+		gfs2_qd_dispose(qd);
+		return;
+	}
+
 	qd->qd_lockref.count = 0;
 	list_lru_add(&gfs2_qd_lru, &qd->qd_lru);
 	spin_unlock(&qd->qd_lockref.lock);
-
 }
 
 static int slot_get(struct gfs2_quota_data *qd)
@@ -1465,16 +1479,33 @@ void gfs2_quota_cleanup(struct gfs2_sbd *sdp)
 {
 	struct gfs2_quota_data *qd;
 	LIST_HEAD(dispose);
+	int count;
+
+	BUG_ON(test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags));
 
 	spin_lock(&qd_lock);
 	list_for_each_entry(qd, &sdp->sd_quota_list, qd_list) {
+		spin_lock(&qd->qd_lockref.lock);
+		if (qd->qd_lockref.count != 0) {
+			spin_unlock(&qd->qd_lockref.lock);
+			continue;
+		}
+		lockref_mark_dead(&qd->qd_lockref);
+		spin_unlock(&qd->qd_lockref.lock);
+
 		list_lru_del(&gfs2_qd_lru, &qd->qd_lru);
 		list_add(&qd->qd_lru, &dispose);
 	}
 	spin_unlock(&qd_lock);
 
 	gfs2_qd_list_dispose(&dispose);
-	gfs2_assert_warn(sdp, !atomic_read(&sdp->sd_quota_count));
+
+	wait_event_timeout(sdp->sd_kill_wait,
+		(count = atomic_read(&sdp->sd_quota_count)) == 0,
+		HZ * 60);
+
+	if (count != 0)
+		fs_err(sdp, "%d left-over quota data objects\n", count);
 
 	kvfree(sdp->sd_quota_bitmap);
 	sdp->sd_quota_bitmap = NULL;