ocfs2: Better I/O error handling in heartbeat

Propagate errors received in o2hb_bio_end_io() back to the heartbeat thread
so it can skip re-arming the timer.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

fs/ocfs2/cluster/heartbeat.c

@@ -153,6 +153,7 @@ struct o2hb_region {
 struct o2hb_bio_wait_ctxt {
 	atomic_t          wc_num_reqs;
 	struct completion wc_io_complete;
+	int               wc_error;
 };
 
 static void o2hb_write_timeout(void *arg)
@@ -186,6 +187,7 @@ static inline void o2hb_bio_wait_init(struct o2hb_bio_wait_ctxt *wc,
 {
 	atomic_set(&wc->wc_num_reqs, num_ios);
 	init_completion(&wc->wc_io_complete);
+	wc->wc_error = 0;
 }
 
 /* Used in error paths too */
@@ -218,8 +220,10 @@ static int o2hb_bio_end_io(struct bio *bio,
 {
 	struct o2hb_bio_wait_ctxt *wc = bio->bi_private;
 
-	if (error)
+	if (error) {
 		mlog(ML_ERROR, "IO Error %d\n", error);
+		wc->wc_error = error;
+	}
 
 	if (bio->bi_size)
 		return 1;
@@ -390,6 +394,8 @@ static int o2hb_read_slots(struct o2hb_region *reg,
 
 bail_and_wait:
 	o2hb_wait_on_io(reg, &wc);
+	if (wc.wc_error && !status)
+		status = wc.wc_error;
 
 	if (bios) {
 		for(i = 0; i < num_bios; i++)
@@ -790,20 +796,24 @@ static int o2hb_highest_node(unsigned long *nodes,
 	return highest;
 }
 
-static void o2hb_do_disk_heartbeat(struct o2hb_region *reg)
+static int o2hb_do_disk_heartbeat(struct o2hb_region *reg)
 {
 	int i, ret, highest_node, change = 0;
 	unsigned long configured_nodes[BITS_TO_LONGS(O2NM_MAX_NODES)];
 	struct bio *write_bio;
 	struct o2hb_bio_wait_ctxt write_wc;
 
-	if (o2nm_configured_node_map(configured_nodes, sizeof(configured_nodes)))
-		return;
+	ret = o2nm_configured_node_map(configured_nodes,
+				       sizeof(configured_nodes));
+	if (ret) {
+		mlog_errno(ret);
+		return ret;
+	}
 
 	highest_node = o2hb_highest_node(configured_nodes, O2NM_MAX_NODES);
 	if (highest_node >= O2NM_MAX_NODES) {
 		mlog(ML_NOTICE, "ocfs2_heartbeat: no configured nodes found!\n");
-		return;
+		return -EINVAL;
 	}
 
 	/* No sense in reading the slots of nodes that don't exist
@@ -813,7 +823,7 @@ static void o2hb_do_disk_heartbeat(struct o2hb_region *reg)
 	ret = o2hb_read_slots(reg, highest_node + 1);
 	if (ret < 0) {
 		mlog_errno(ret);
-		return;
+		return ret;
 	}
 
 	/* With an up to date view of the slots, we can check that no
@@ -831,7 +841,7 @@ static void o2hb_do_disk_heartbeat(struct o2hb_region *reg)
 	ret = o2hb_issue_node_write(reg, &write_bio, &write_wc);
 	if (ret < 0) {
 		mlog_errno(ret);
-		return;
+		return ret;
 	}
 
 	i = -1;
@@ -847,6 +857,15 @@ static void o2hb_do_disk_heartbeat(struct o2hb_region *reg)
 	 */
 	o2hb_wait_on_io(reg, &write_wc);
 	bio_put(write_bio);
+	if (write_wc.wc_error) {
+		/* Do not re-arm the write timeout on I/O error - we
+		 * can't be sure that the new block ever made it to
+		 * disk */
+		mlog(ML_ERROR, "Write error %d on device \"%s\"\n",
+		     write_wc.wc_error, reg->hr_dev_name);
+		return write_wc.wc_error;
+	}
+
 	o2hb_arm_write_timeout(reg);
 
 	/* let the person who launched us know when things are steady */
@@ -854,6 +873,8 @@ static void o2hb_do_disk_heartbeat(struct o2hb_region *reg)
 		if (atomic_dec_and_test(&reg->hr_steady_iterations))
 			wake_up(&o2hb_steady_queue);
 	}
+
+	return 0;
 }
 
 /* Subtract b from a, storing the result in a. a *must* have a larger
@@ -913,7 +934,10 @@ static int o2hb_thread(void *data)
 		 * likely to time itself out. */
 		do_gettimeofday(&before_hb);
 
-		o2hb_do_disk_heartbeat(reg);
+		i = 0;
+		do {
+			ret = o2hb_do_disk_heartbeat(reg);
+		} while (ret && ++i < 2);
 
 		do_gettimeofday(&after_hb);
 		elapsed_msec = o2hb_elapsed_msecs(&before_hb, &after_hb);