virtio: blk/scsi: use block layer helpers to calculate num of queues

The calculation of the upper limit for queues does not depend solely on
the number of possible CPUs; for example, the isolcpus kernel
command-line option must also be considered.

To account for this, the block layer provides a helper function to
retrieve the maximum number of queues. Use it to set an appropriate
upper queue number limit.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Daniel Wagner <wagi@kernel.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20250617-isolcpus-queue-counters-v1-5-13923686b54b@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 30bca8cb7106040d3bbb11ba9e0b546510534324..e649fa67bac16b4f0c6e8e8f0e6bec111897c355 100644 (file)
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -976,9 +976,8 @@ static int init_vq(struct virtio_blk *vblk)
                return -EINVAL;
        }
 
-       num_vqs = min_t(unsigned int,
-                       min_not_zero(num_request_queues, nr_cpu_ids),
-                       num_vqs);
+       num_vqs = blk_mq_num_possible_queues(
+                       min_not_zero(num_request_queues, num_vqs));
 
        num_poll_vqs = min_t(unsigned int, poll_queues, num_vqs - 1);
 

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 21ce3e9401929cd273fde08b0944e8b47e1e66cc..96a69edddbe5555574fc8fed1ba7c82a99df4472 100644 (file)
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -919,6 +919,7 @@ static int virtscsi_probe(struct virtio_device *vdev)
        /* We need to know how many queues before we allocate. */
        num_queues = virtscsi_config_get(vdev, num_queues) ? : 1;
        num_queues = min_t(unsigned int, nr_cpu_ids, num_queues);
+       num_queues = blk_mq_num_possible_queues(num_queues);
 
        num_targets = virtscsi_config_get(vdev, max_target) + 1;