dm mpath: remove extra nesting in map function

Return early for case when no path exists, and when the
pathgroup isn't ready. This eliminates the need for
extra nesting for the the common case.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>

drivers/md/dm-mpath.c

@@ -398,29 +398,31 @@ static int multipath_map(struct dm_target *ti, struct request *clone,
 
 	pgpath = m->current_pgpath;
 
-	if (pgpath) {
-		if (pg_ready(m)) {
-			if (set_mapinfo(m, map_context) < 0)
-				/* ENOMEM, requeue */
-				goto out_unlock;
-
-			bdev = pgpath->path.dev->bdev;
-			clone->q = bdev_get_queue(bdev);
-			clone->rq_disk = bdev->bd_disk;
-			clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
-			mpio = map_context->ptr;
-			mpio->pgpath = pgpath;
-			mpio->nr_bytes = nr_bytes;
-			if (pgpath->pg->ps.type->start_io)
-				pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
-							      &pgpath->path,
-							      nr_bytes);
-			r = DM_MAPIO_REMAPPED;
-			goto out_unlock;
-		}
+	if (!pgpath) {
+		if (!__must_push_back(m))
+			r = -EIO;	/* Failed */
+		goto out_unlock;
+	}
+	if (!pg_ready(m)) {
 		__pg_init_all_paths(m);
-	} else if (!__must_push_back(m))
-		r = -EIO;	/* Failed */
+		goto out_unlock;
+	}
+	if (set_mapinfo(m, map_context) < 0)
+		/* ENOMEM, requeue */
+		goto out_unlock;
+
+	bdev = pgpath->path.dev->bdev;
+	clone->q = bdev_get_queue(bdev);
+	clone->rq_disk = bdev->bd_disk;
+	clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
+	mpio = map_context->ptr;
+	mpio->pgpath = pgpath;
+	mpio->nr_bytes = nr_bytes;
+	if (pgpath->pg->ps.type->start_io)
+		pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
+					      &pgpath->path,
+					      nr_bytes);
+	r = DM_MAPIO_REMAPPED;
 
 out_unlock:
 	spin_unlock_irqrestore(&m->lock, flags);