// SPDX-License-Identifier: GPL-2.0

  /*
   * Copyright (c) 2017 Sagi Grimberg.

   */
  #include <linux/blk-mq.h>
  #include <linux/blk-mq-rdma.h>
  #include <rdma/ib_verbs.h>
  
  /**
   * blk_mq_rdma_map_queues - provide a default queue mapping for rdma device

   * @map:	CPU to hardware queue map.
   * @dev:	rdma device to provide a mapping for.

   * @first_vec:	first interrupt vectors to use for queues (usually 0)
   *
   * This function assumes the rdma device @dev has at least as many available
   * interrupt vetors as @set has queues.  It will then query it's affinity mask
   * and built queue mapping that maps a queue to the CPUs that have irq affinity
   * for the corresponding vector.
   *
   * In case either the driver passed a @dev with less vectors than
   * @set->nr_hw_queues, or @dev does not provide an affinity mask for a
   * vector, we fallback to the naive mapping.
   */

  int blk_mq_rdma_map_queues(struct blk_mq_queue_map *map,

  		struct ib_device *dev, int first_vec)
  {
  	const struct cpumask *mask;
  	unsigned int queue, cpu;

  	for (queue = 0; queue < map->nr_queues; queue++) {

  		mask = ib_get_vector_affinity(dev, first_vec + queue);
  		if (!mask)
  			goto fallback;
  
  		for_each_cpu(cpu, mask)

  			map->mq_map[cpu] = map->queue_offset + queue;

  	}
  
  	return 0;
  
  fallback:

  	return blk_mq_map_queues(map);

  }
  EXPORT_SYMBOL_GPL(blk_mq_rdma_map_queues);