nvme: fix the check for duplicate unique identifiers

nvme_subsys_check_duplicate_ids should needs to return an error if any of
the identifiers matches, not just if all of them match.  But it does not
need to and should not look at the CSI value for this sanity check.

Rewrite the logic to be separate from nvme_ns_ids_equal and optimize it
by reducing duplicate checks for non-present identifiers.

Fixes: ed754e5 ("nvme: track shared namespaces")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

drivers/nvme/host/core.c

@@ -1716,13 +1716,6 @@ static void nvme_config_discard(struct gendisk *disk, struct nvme_ns *ns)
 		blk_queue_max_write_zeroes_sectors(queue, UINT_MAX);
 }
 
-static bool nvme_ns_ids_valid(struct nvme_ns_ids *ids)
-{
-	return !uuid_is_null(&ids->uuid) ||
-		memchr_inv(ids->nguid, 0, sizeof(ids->nguid)) ||
-		memchr_inv(ids->eui64, 0, sizeof(ids->eui64));
-}
-
 static bool nvme_ns_ids_equal(struct nvme_ns_ids *a, struct nvme_ns_ids *b)
 {
 	return uuid_equal(&a->uuid, &b->uuid) &&
@@ -3676,12 +3669,21 @@ static struct nvme_ns_head *nvme_find_ns_head(struct nvme_subsystem *subsys,
 static int nvme_subsys_check_duplicate_ids(struct nvme_subsystem *subsys,
 		struct nvme_ns_ids *ids)
 {
+	bool has_uuid = !uuid_is_null(&ids->uuid);
+	bool has_nguid = memchr_inv(ids->nguid, 0, sizeof(ids->nguid));
+	bool has_eui64 = memchr_inv(ids->eui64, 0, sizeof(ids->eui64));
 	struct nvme_ns_head *h;
 
 	lockdep_assert_held(&subsys->lock);
 
 	list_for_each_entry(h, &subsys->nsheads, entry) {
-		if (nvme_ns_ids_valid(ids) && nvme_ns_ids_equal(ids, &h->ids))
+		if (has_uuid && uuid_equal(&ids->uuid, &h->ids.uuid))
+			return -EINVAL;
+		if (has_nguid &&
+		    memcmp(&ids->nguid, &h->ids.nguid, sizeof(ids->nguid)) == 0)
+			return -EINVAL;
+		if (has_eui64 &&
+		    memcmp(&ids->eui64, &h->ids.eui64, sizeof(ids->eui64)) == 0)
 			return -EINVAL;
 	}