NVMe: Simplify queue lookup

Fill in all the num_possible_cpus() entries with duplicate pointers.
This reduces the complexity of the frequently-called get_nvmeq(), as
well as avoiding a bug in it when there are fewer queues than CPUs.

Reported-by: Shane Michael Matthews <shane.matthews@intel.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>

diff --git a/drivers/block/nvme.c b/drivers/block/nvme.c
index 8d3c0b7..f94f173 100644 (file)
--- a/drivers/block/nvme.c
+++ b/drivers/block/nvme.c
@@ -221,12 +221,7 @@ static void cancel_cmdid_data(struct nvme_queue *nvmeq, int cmdid)
 
 static struct nvme_queue *get_nvmeq(struct nvme_ns *ns)
 {
-       int qid, cpu = get_cpu();
-       if (cpu < ns->dev->queue_count)
-               qid = cpu + 1;
-       else
-               qid = (cpu % rounddown_pow_of_two(ns->dev->queue_count)) + 1;
-       return ns->dev->queues[qid];
+       return ns->dev->queues[get_cpu() + 1];
 }
 
 static void put_nvmeq(struct nvme_queue *nvmeq)
@@ -1316,6 +1311,11 @@ static int __devinit nvme_setup_io_queues(struct nvme_dev *dev)
                dev->queue_count++;
        }
 
+       for (; i < num_possible_cpus(); i++) {
+               int target = i % rounddown_pow_of_two(dev->queue_count - 1);
+               dev->queues[i + 1] = dev->queues[target + 1];
+       }
+
        return 0;
 }