blk-mq: save default hctx into ctx->hctxs for not-supported type

Currently, we check whether the hctx type is supported every time
in hot path. Actually, this is not necessary, we could save the
default hctx into ctx->hctxs if the type is not supported when
map swqueues and use it directly with ctx->hctxs[type].

We also needn't check whether the poll is enabled or not, because
the caller would clear the REQ_HIPRI in that case.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 445d0a2..8a825ae 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2431,8 +2431,11 @@ static void blk_mq_map_swqueue(struct request_queue *q)
 
                ctx = per_cpu_ptr(q->queue_ctx, i);
                for (j = 0; j < set->nr_maps; j++) {
-                       if (!set->map[j].nr_queues)
+                       if (!set->map[j].nr_queues) {
+                               ctx->hctxs[j] = blk_mq_map_queue_type(q,
+                                               HCTX_TYPE_DEFAULT, i);
                                continue;
+                       }
 
                        hctx = blk_mq_map_queue_type(q, j, i);
                        ctx->hctxs[j] = hctx;
@@ -2455,6 +2458,10 @@ static void blk_mq_map_swqueue(struct request_queue *q)
                         */
                        BUG_ON(!hctx->nr_ctx);
                }
+
+               for (; j < HCTX_MAX_TYPES; j++)
+                       ctx->hctxs[j] = blk_mq_map_queue_type(q,
+                                       HCTX_TYPE_DEFAULT, i);
        }
 
        mutex_unlock(&q->sysfs_lock);

diff --git a/block/blk-mq.h b/block/blk-mq.h
index 9fb0626..14b7efb 100644 (file)
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -106,15 +106,12 @@ static inline struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q,
 {
        enum hctx_type type = HCTX_TYPE_DEFAULT;
 
-       if ((flags & REQ_HIPRI) &&
-           q->tag_set->nr_maps > HCTX_TYPE_POLL && 
-           q->tag_set->map[HCTX_TYPE_POLL].nr_queues &&
-           test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
+       /*
+        * The caller ensure that if REQ_HIPRI, poll must be enabled.
+        */
+       if (flags & REQ_HIPRI)
                type = HCTX_TYPE_POLL;
-
-       else if (((flags & REQ_OP_MASK) == REQ_OP_READ) &&
-                q->tag_set->nr_maps > HCTX_TYPE_READ &&
-                q->tag_set->map[HCTX_TYPE_READ].nr_queues)
+       else if ((flags & REQ_OP_MASK) == REQ_OP_READ)
                type = HCTX_TYPE_READ;
        
        return ctx->hctxs[type];