dm mpath: merge do_end_io_bio into multipath_end_io_bio

This simplifies the code and especially the error passing a bit and
will help with the next patch.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/md/dm-mpath.c

@@ -1510,24 +1510,24 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone,
 	return r;
 }
 
-static int do_end_io_bio(struct multipath *m, struct bio *clone,
-			 int error, struct dm_mpath_io *mpio)
+static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone, int error)
 {
+	struct multipath *m = ti->private;
+	struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
+	struct pgpath *pgpath = mpio->pgpath;
 	unsigned long flags;
 
-	if (!error)
-		return 0;	/* I/O complete */
-
-	if (noretry_error(error))
-		return error;
+	if (!error || noretry_error(error))
+		goto done;
 
-	if (mpio->pgpath)
-		fail_path(mpio->pgpath);
+	if (pgpath)
+		fail_path(pgpath);
 
 	if (atomic_read(&m->nr_valid_paths) == 0 &&
 	    !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
 		dm_report_EIO(m);
-		return -EIO;
+		error = -EIO;
+		goto done;
 	}
 
 	/* Queue for the daemon to resubmit */
@@ -1539,28 +1539,16 @@ static int do_end_io_bio(struct multipath *m, struct bio *clone,
 	if (!test_bit(MPATHF_QUEUE_IO, &m->flags))
 		queue_work(kmultipathd, &m->process_queued_bios);
 
-	return DM_ENDIO_INCOMPLETE;
-}
-
-static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone, int error)
-{
-	struct multipath *m = ti->private;
-	struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
-	struct pgpath *pgpath;
-	struct path_selector *ps;
-	int r;
-
-	BUG_ON(!mpio);
-
-	r = do_end_io_bio(m, clone, error, mpio);
-	pgpath = mpio->pgpath;
+	error = DM_ENDIO_INCOMPLETE;
+done:
 	if (pgpath) {
-		ps = &pgpath->pg->ps;
+		struct path_selector *ps = &pgpath->pg->ps;
+
 		if (ps->type->end_io)
 			ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
 	}
 
-	return r;
+	return error;
 }
 
 /*