blk-mq: introduce blk_mq_hw_queue_first_cpu() to figure out first cpu

This patch introduces helper of blk_mq_hw_queue_first_cpu() for
figuring out the hctx's first cpu, and code duplication can be
avoided.

Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index db178c5..e05bd10 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1335,6 +1335,15 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
        hctx_unlock(hctx, srcu_idx);
 }
 
+static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx)
+{
+       int cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask);
+
+       if (cpu >= nr_cpu_ids)
+               cpu = cpumask_first(hctx->cpumask);
+       return cpu;
+}
+
 /*
  * It'd be great if the workqueue API had a way to pass
  * in a mask and had some smarts for more clever placement.
@@ -1354,14 +1363,7 @@ select_cpu:
                next_cpu = cpumask_next_and(next_cpu, hctx->cpumask,
                                cpu_online_mask);
                if (next_cpu >= nr_cpu_ids)
-                       next_cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask);
-
-               /*
-                * No online CPU is found, so have to make sure hctx->next_cpu
-                * is set correctly for not breaking workqueue.
-                */
-               if (next_cpu >= nr_cpu_ids)
-                       next_cpu = cpumask_first(hctx->cpumask);
+                       next_cpu = blk_mq_first_mapped_cpu(hctx);
                hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
        }
 
@@ -2430,10 +2432,7 @@ static void blk_mq_map_swqueue(struct request_queue *q)
                /*
                 * Initialize batch roundrobin counts
                 */
-               hctx->next_cpu = cpumask_first_and(hctx->cpumask,
-                               cpu_online_mask);
-               if (hctx->next_cpu >= nr_cpu_ids)
-                       hctx->next_cpu = cpumask_first(hctx->cpumask);
+               hctx->next_cpu = blk_mq_first_mapped_cpu(hctx);
                hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
        }
 }