nvme: add the Apple shared tag workaround to nvme_alloc_io_tag_set

Add the apple shared tag workaround to nvme_alloc_io_tag_set to prepare
for using that helper in the PCIe driver.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

drivers/nvme/host/core.c

@@ -4899,7 +4899,13 @@ int nvme_alloc_io_tag_set(struct nvme_ctrl *ctrl, struct blk_mq_tag_set *set,
 	memset(set, 0, sizeof(*set));
 	set->ops = ops;
 	set->queue_depth = ctrl->sqsize + 1;
-	if (ctrl->ops->flags & NVME_F_FABRICS)
+	/*
+	 * Some Apple controllers requires tags to be unique across admin and
+	 * the (only) I/O queue, so reserve the first 32 tags of the I/O queue.
+	 */
+	if (ctrl->quirks & NVME_QUIRK_SHARED_TAGS)
+		set->reserved_tags = NVME_AQ_DEPTH;
+	else if (ctrl->ops->flags & NVME_F_FABRICS)
 		set->reserved_tags = NVMF_RESERVED_TAGS;
 	set->numa_node = ctrl->numa_node;
 	set->flags = BLK_MQ_F_SHOULD_MERGE;