1 files changed, 44 insertions, 0 deletions
diff --git a/block/blk-mq-rdma.c b/block/blk-mq-rdma.c
new file mode 100644
index 000000000..14f968e58
--- /dev/null
+++ b/block/blk-mq-rdma.c
@@ -0,0 +1,44 @@
+// 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);