md/raid1: factor out flush_bio_list()

flush_pending_writes() and raid1_unplug() each contain identical
copies of a fairly large slab of code.  So factor that out into
new flush_bio_list() to simplify maintenance.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

drivers/md/raid1.c

@@ -787,20 +787,9 @@ static int raid1_congested(struct mddev *mddev, int bits)
 	return ret;
 }
 
-static void flush_pending_writes(struct r1conf *conf)
+static void flush_bio_list(struct r1conf *conf, struct bio *bio)
 {
-	/* Any writes that have been queued but are awaiting
-	 * bitmap updates get flushed here.
-	 */
-	spin_lock_irq(&conf->device_lock);
-
-	if (conf->pending_bio_list.head) {
-		struct bio *bio;
-		bio = bio_list_get(&conf->pending_bio_list);
-		conf->pending_count = 0;
-		spin_unlock_irq(&conf->device_lock);
-		/* flush any pending bitmap writes to
-		 * disk before proceeding w/ I/O */
+	/* flush any pending bitmap writes to disk before proceeding w/ I/O */
 	bitmap_unplug(conf->mddev->bitmap);
 	wake_up(&conf->wait_barrier);
 
@@ -820,6 +809,21 @@ static void flush_pending_writes(struct r1conf *conf)
 			generic_make_request(bio);
 		bio = next;
 	}
+}
+
+static void flush_pending_writes(struct r1conf *conf)
+{
+	/* Any writes that have been queued but are awaiting
+	 * bitmap updates get flushed here.
+	 */
+	spin_lock_irq(&conf->device_lock);
+
+	if (conf->pending_bio_list.head) {
+		struct bio *bio;
+		bio = bio_list_get(&conf->pending_bio_list);
+		conf->pending_count = 0;
+		spin_unlock_irq(&conf->device_lock);
+		flush_bio_list(conf, bio);
 	} else
 		spin_unlock_irq(&conf->device_lock);
 }
@@ -1152,25 +1156,7 @@ static void raid1_unplug(struct blk_plug_cb *cb, bool from_schedule)
 
 	/* we aren't scheduling, so we can do the write-out directly. */
 	bio = bio_list_get(&plug->pending);
-	bitmap_unplug(mddev->bitmap);
-	wake_up(&conf->wait_barrier);
-
-	while (bio) { /* submit pending writes */
-		struct bio *next = bio->bi_next;
-		struct md_rdev *rdev = (void*)bio->bi_bdev;
-		bio->bi_next = NULL;
-		bio->bi_bdev = rdev->bdev;
-		if (test_bit(Faulty, &rdev->flags)) {
-			bio->bi_error = -EIO;
-			bio_endio(bio);
-		} else if (unlikely((bio_op(bio) == REQ_OP_DISCARD) &&
-				    !blk_queue_discard(bdev_get_queue(bio->bi_bdev))))
-			/* Just ignore it */
-			bio_endio(bio);
-		else
-			generic_make_request(bio);
-		bio = next;
-	}
+	flush_bio_list(conf, bio);
 	kfree(plug);
 }