gfs2: Report when glocks cannot be freed for a long time

When glocks cannot be freed for a long time, avoid the "task blocked for
more than N seconds" messages and report how many glocks are still
outstanding, instead.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/glock.c

@@ -2248,13 +2248,25 @@ void gfs2_gl_dq_holders(struct gfs2_sbd *sdp)
 
 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
 {
+	unsigned long start = jiffies;
+	bool timed_out = false;
+
 	set_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags);
 	flush_workqueue(glock_workqueue);
 	glock_hash_walk(clear_glock, sdp);
 	flush_workqueue(glock_workqueue);
-	wait_event_timeout(sdp->sd_kill_wait,
-			   atomic_read(&sdp->sd_glock_disposal) == 0,
-			   HZ * 600);
+	while (!timed_out) {
+		wait_event_timeout(sdp->sd_kill_wait,
+				   !atomic_read(&sdp->sd_glock_disposal),
+				   HZ * 60);
+		if (!atomic_read(&sdp->sd_glock_disposal))
+			break;
+		timed_out = time_after(jiffies, start + (HZ * 600));
+		fs_warn(sdp, "%u glocks left after %u seconds%s\n",
+			atomic_read(&sdp->sd_glock_disposal),
+			jiffies_to_msecs(jiffies - start) / 1000,
+			timed_out ? ":" : "; still waiting");
+	}
 	gfs2_lm_unmount(sdp);
 	gfs2_free_dead_glocks(sdp);
 	glock_hash_walk(dump_glock_func, sdp);