md/raid5: Refactor raid5_get_active_stripe()

Refactor raid5_get_active_stripe() without the gotos with an
explicit infinite loop and some additional nesting.
Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Song Liu <song@kernel.org>

drivers/md/raid5.c

@@ -811,44 +811,45 @@ static struct stripe_head *__raid5_get_active_stripe(struct r5conf *conf,
 
 	spin_lock_irq(conf->hash_locks + hash);
 
-retry:
+	for (;;) {
 		if (!noquiesce && conf->quiesce) {
 			/*
-		 * Must release the reference to batch_last before waiting,
-		 * on quiesce, otherwise the batch_last will hold a reference
-		 * to a stripe and raid5_quiesce() will deadlock waiting for
-		 * active_stripes to go to zero.
+			 * Must release the reference to batch_last before
+			 * waiting, on quiesce, otherwise the batch_last will
+			 * hold a reference to a stripe and raid5_quiesce()
+			 * will deadlock waiting for active_stripes to go to
+			 * zero.
 			 */
 			if (ctx && ctx->batch_last) {
 				raid5_release_stripe(ctx->batch_last);
 				ctx->batch_last = NULL;
 			}
 
-		wait_event_lock_irq(conf->wait_for_quiescent, !conf->quiesce,
+			wait_event_lock_irq(conf->wait_for_quiescent,
+					    !conf->quiesce,
 					    *(conf->hash_locks + hash));
 		}
 
-	sh = find_get_stripe(conf, sector, conf->generation - previous, hash);
+		sh = find_get_stripe(conf, sector, conf->generation - previous,
+				     hash);
 		if (sh)
-		goto out;
-
-	if (test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state))
-		goto wait_for_stripe;
+			break;
 
+		if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state)) {
 			sh = get_free_stripe(conf, hash);
 			if (sh) {
 				r5c_check_stripe_cache_usage(conf);
 				init_stripe(sh, sector, previous);
 				atomic_inc(&sh->count);
-		goto out;
+				break;
 			}
 
 			if (!test_bit(R5_DID_ALLOC, &conf->cache_state))
 				set_bit(R5_ALLOC_MORE, &conf->cache_state);
+		}
 
-wait_for_stripe:
 		if (noblock)
-		goto out;
+			break;
 
 		set_bit(R5_INACTIVE_BLOCKED, &conf->cache_state);
 		r5l_wake_reclaim(conf->log, 0);
@@ -856,9 +857,8 @@ static struct stripe_head *__raid5_get_active_stripe(struct r5conf *conf,
 				    is_inactive_blocked(conf, hash),
 				    *(conf->hash_locks + hash));
 		clear_bit(R5_INACTIVE_BLOCKED, &conf->cache_state);
-	goto retry;
+	}
 
-out:
 	spin_unlock_irq(conf->hash_locks + hash);
 	return sh;
 }