md/raid5: Cleanup setup_conf() error returns

Be more careful about the error returns. Most errors in this function
are actually ENOMEM, but it forcibly returns EIO if conf has been
allocated.

Instead return ret and ensure it is set appropriately before each goto
abort.
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Song Liu <song@kernel.org>

drivers/md/raid5.c

@@ -7163,7 +7163,7 @@ static struct r5conf *setup_conf(struct mddev *mddev)
 	int i;
 	int group_cnt;
 	struct r5worker_group *new_group;
-	int ret;
+	int ret = -ENOMEM;
 
 	if (mddev->new_level != 5
 	    && mddev->new_level != 4
@@ -7222,6 +7222,7 @@ static struct r5conf *setup_conf(struct mddev *mddev)
 	spin_lock_init(&conf->device_lock);
 	seqcount_spinlock_init(&conf->gen_lock, &conf->device_lock);
 	mutex_init(&conf->cache_size_mutex);
+
 	init_waitqueue_head(&conf->wait_for_quiescent);
 	init_waitqueue_head(&conf->wait_for_stripe);
 	init_waitqueue_head(&conf->wait_for_overlap);
@@ -7299,11 +7300,13 @@ static struct r5conf *setup_conf(struct mddev *mddev)
 
 	conf->level = mddev->new_level;
 	conf->chunk_sectors = mddev->new_chunk_sectors;
-	if (raid5_alloc_percpu(conf) != 0)
+	ret = raid5_alloc_percpu(conf);
+	if (ret)
 		goto abort;
 
 	pr_debug("raid456: run(%s) called.\n", mdname(mddev));
 
+	ret = -EIO;
 	rdev_for_each(rdev, mddev) {
 		raid_disk = rdev->raid_disk;
 		if (raid_disk >= max_disks
@@ -7367,6 +7370,7 @@ static struct r5conf *setup_conf(struct mddev *mddev)
 	if (grow_stripes(conf, conf->min_nr_stripes)) {
 		pr_warn("md/raid:%s: couldn't allocate %dkB for buffers\n",
 			mdname(mddev), memory);
+		ret = -ENOMEM;
 		goto abort;
 	} else
 		pr_debug("md/raid:%s: allocated %dkB\n", mdname(mddev), memory);
@@ -7380,7 +7384,8 @@ static struct r5conf *setup_conf(struct mddev *mddev)
 	conf->shrinker.count_objects = raid5_cache_count;
 	conf->shrinker.batch = 128;
 	conf->shrinker.flags = 0;
-	if (register_shrinker(&conf->shrinker)) {
+	ret = register_shrinker(&conf->shrinker);
+	if (ret) {
 		pr_warn("md/raid:%s: couldn't register shrinker.\n",
 			mdname(mddev));
 		goto abort;
@@ -7391,17 +7396,16 @@ static struct r5conf *setup_conf(struct mddev *mddev)
 	if (!conf->thread) {
 		pr_warn("md/raid:%s: couldn't allocate thread.\n",
 			mdname(mddev));
+		ret = -ENOMEM;
 		goto abort;
 	}
 
 	return conf;
 
  abort:
-	if (conf) {
+	if (conf)
 		free_conf(conf);
-		return ERR_PTR(-EIO);
-	} else
-		return ERR_PTR(-ENOMEM);
+	return ERR_PTR(ret);
 }
 
 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)