md/raid5: minor code cleanups in make_request.

... and to be certain the that make_request doesn't wait forever,
add a 'wake_up' when ->reshape_progress has been set to MaxSector
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/raid5.c

@@ -3637,10 +3637,9 @@ static int make_request(struct request_queue *q, struct bio * bi)
 
 	retry:
 		previous = 0;
-		prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
-		if (likely(conf->reshape_progress == MaxSector))
 		disks = conf->raid_disks;
-		else {
+		prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
+		if (unlikely(conf->reshape_progress != MaxSector)) {
 			/* spinlock is needed as reshape_progress may be
 			 * 64bit on a 32bit platform, and so it might be
 			 * possible to see a half-updated value
@@ -3650,7 +3649,6 @@ static int make_request(struct request_queue *q, struct bio * bi)
 			 * to check again.
 			 */
 			spin_lock_irq(&conf->device_lock);
-			disks = conf->raid_disks;
 			if (mddev->delta_disks < 0
 			    ? logical_sector < conf->reshape_progress
 			    : logical_sector >= conf->reshape_progress) {
@@ -3679,7 +3677,7 @@ static int make_request(struct request_queue *q, struct bio * bi)
 		sh = get_active_stripe(conf, new_sector, previous,
 				       (bi->bi_rw&RWA_MASK));
 		if (sh) {
-			if (unlikely(conf->reshape_progress != MaxSector)) {
+			if (unlikely(previous)) {
 				/* expansion might have moved on while waiting for a
 				 * stripe, so we must do the range check again.
 				 * Expansion could still move past after this
@@ -3690,10 +3688,9 @@ static int make_request(struct request_queue *q, struct bio * bi)
 				 */
 				int must_retry = 0;
 				spin_lock_irq(&conf->device_lock);
-				if ((mddev->delta_disks < 0
+				if (mddev->delta_disks < 0
 				    ? logical_sector >= conf->reshape_progress
 				    : logical_sector < conf->reshape_progress)
-				    && previous)
 					/* mismatch, need to try again */
 					must_retry = 1;
 				spin_unlock_irq(&conf->device_lock);
@@ -4977,6 +4974,7 @@ static void end_reshape(raid5_conf_t *conf)
 		conf->previous_raid_disks = conf->raid_disks;
 		conf->reshape_progress = MaxSector;
 		spin_unlock_irq(&conf->device_lock);
+		wake_up(&conf->wait_for_overlap);
 
 		/* read-ahead size must cover two whole stripes, which is
 		 * 2 * (datadisks) * chunksize where 'n' is the number of raid devices