bcache: fix error info in register_bcache()

In register_bcache(), there are several cases we didn't set
correct error info (return value and/or error message):
- if kzalloc() fails, it needs to return ENOMEM and print
"cannot allocate memory";
- if register_cache() fails, it's better to propagate its
return value rather than using default EINVAL.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Coly Li <colyli@suse.de>
Link: https://lore.kernel.org/r/20211020143812.6403-4-colyli@suse.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/md/bcache/super.c

@@ -2617,8 +2617,11 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 	if (SB_IS_BDEV(sb)) {
 		struct cached_dev *dc = kzalloc(sizeof(*dc), GFP_KERNEL);
 
-		if (!dc)
+		if (!dc) {
+			ret = -ENOMEM;
+			err = "cannot allocate memory";
 			goto out_put_sb_page;
+		}
 
 		mutex_lock(&bch_register_lock);
 		ret = register_bdev(sb, sb_disk, bdev, dc);
@@ -2629,11 +2632,15 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 	} else {
 		struct cache *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
 
-		if (!ca)
+		if (!ca) {
+			ret = -ENOMEM;
+			err = "cannot allocate memory";
 			goto out_put_sb_page;
+		}
 
 		/* blkdev_put() will be called in bch_cache_release() */
-		if (register_cache(sb, sb_disk, bdev, ca) != 0)
+		ret = register_cache(sb, sb_disk, bdev, ca);
+		if (ret)
 			goto out_free_sb;
 	}