Update blk-mq-virtio.c

block/blk-mq-virtio.c

@@ -1,13 +1,3 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Copyright (c) 2016 Christoph Hellwig.
- */
-#include <linux/device.h>
-#include <linux/blk-mq-virtio.h>
-#include <linux/virtio_config.h>
-#include <linux/module.h>
-#include "blk-mq.h"
-
 /**
  * blk_mq_virtio_map_queues - provide a default queue mapping for virtio device
  * @qmap:	CPU to hardware queue map.
@@ -16,20 +6,26 @@
  *
  * This function assumes the virtio device @vdev has at least as many available
  * interrupt vectors as @set has queues.  It will then query the vector
- * corresponding to each queue for it's affinity mask and built queue mapping
- * that maps a queue to the CPUs that have irq affinity for the corresponding
- * vector.
+ * corresponding to each queue for its affinity mask and build a queue mapping
+ * that maps a queue to the CPUs that have IRQ affinity for the corresponding
+ * vector. If the number of available vectors is less than the number of queues,
+ * it dynamically allocates vectors and assigns queues accordingly.
  */
 void blk_mq_virtio_map_queues(struct blk_mq_queue_map *qmap,
 		struct virtio_device *vdev, int first_vec)
 {
 	const struct cpumask *mask;
 	unsigned int queue, cpu;
+	unsigned int nr_vecs_needed = qmap->nr_queues;
 
 	if (!vdev->config->get_vq_affinity)
 		goto fallback;
 
-	for (queue = 0; queue < qmap->nr_queues; queue++) {
+	// Ensure the virtio device has at least nr_vecs_needed interrupt vectors
+	if (vdev->config->num_vectors < nr_vecs_needed)
+		nr_vecs_needed = vdev->config->num_vectors;
+
+	for (queue = 0; queue < nr_vecs_needed; queue++) {
 		mask = vdev->config->get_vq_affinity(vdev, first_vec + queue);
 		if (!mask)
 			goto fallback;