1 files changed, 16 insertions, 39 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index e931a0e8e73d..729169d022fc 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1036,10 +1036,11 @@ void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
 EXPORT_SYMBOL(blk_mq_delay_queue);
 
 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
-                                            struct blk_mq_ctx *ctx,
                                             struct request *rq,
                                             bool at_head)
 {
+        struct blk_mq_ctx *ctx = rq->mq_ctx;
+
         trace_block_rq_insert(hctx->queue, rq);
 
         if (at_head)
@@ -1053,20 +1054,16 @@ static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
 {
         struct blk_mq_ctx *ctx = rq->mq_ctx;
 
-        __blk_mq_insert_req_list(hctx, ctx, rq, at_head);
+        __blk_mq_insert_req_list(hctx, rq, at_head);
         blk_mq_hctx_mark_pending(hctx, ctx);
 }
 
 void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
-                bool async)
+                           bool async)
 {
+        struct blk_mq_ctx *ctx = rq->mq_ctx;
         struct request_queue *q = rq->q;
         struct blk_mq_hw_ctx *hctx;
-        struct blk_mq_ctx *ctx = rq->mq_ctx, *current_ctx;
-
-        current_ctx = blk_mq_get_ctx(q);
-        if (!cpu_online(ctx->cpu))
-                rq->mq_ctx = ctx = current_ctx;
 
         hctx = q->mq_ops->map_queue(q, ctx->cpu);
 
@@ -1076,8 +1073,6 @@ void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
 
         if (run_queue)
                 blk_mq_run_hw_queue(hctx, async);
-
-        blk_mq_put_ctx(current_ctx);
 }
 
 static void blk_mq_insert_requests(struct request_queue *q,
@@ -1088,14 +1083,9 @@ static void blk_mq_insert_requests(struct request_queue *q,
 
 {
         struct blk_mq_hw_ctx *hctx;
-        struct blk_mq_ctx *current_ctx;
 
         trace_block_unplug(q, depth, !from_schedule);
 
-        current_ctx = blk_mq_get_ctx(q);
-
-        if (!cpu_online(ctx->cpu))
-                ctx = current_ctx;
         hctx = q->mq_ops->map_queue(q, ctx->cpu);
 
         /*
@@ -1107,15 +1097,14 @@ static void blk_mq_insert_requests(struct request_queue *q,
                 struct request *rq;
 
                 rq = list_first_entry(list, struct request, queuelist);
+                BUG_ON(rq->mq_ctx != ctx);
                 list_del_init(&rq->queuelist);
-                rq->mq_ctx = ctx;
-                __blk_mq_insert_req_list(hctx, ctx, rq, false);
+                __blk_mq_insert_req_list(hctx, rq, false);
         }
         blk_mq_hctx_mark_pending(hctx, ctx);
         spin_unlock(&ctx->lock);
 
         blk_mq_run_hw_queue(hctx, from_schedule);
-        blk_mq_put_ctx(current_ctx);
 }
 
 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
@@ -1630,16 +1619,17 @@ static int blk_mq_alloc_bitmap(struct blk_mq_ctxmap *bitmap, int node)
         return 0;
 }
 
+/*
+ * 'cpu' is going away. splice any existing rq_list entries from this
+ * software queue to the hw queue dispatch list, and ensure that it
+ * gets run.
+ */
 static int blk_mq_hctx_cpu_offline(struct blk_mq_hw_ctx *hctx, int cpu)
 {
-        struct request_queue *q = hctx->queue;
         struct blk_mq_ctx *ctx;
         LIST_HEAD(tmp);
 
-        /*
-         * Move ctx entries to new CPU, if this one is going away.
-         */
-        ctx = __blk_mq_get_ctx(q, cpu);
+        ctx = __blk_mq_get_ctx(hctx->queue, cpu);
 
         spin_lock(&ctx->lock);
         if (!list_empty(&ctx->rq_list)) {
@@ -1651,24 +1641,11 @@ static int blk_mq_hctx_cpu_offline(struct blk_mq_hw_ctx *hctx, int cpu)
         if (list_empty(&tmp))
                 return NOTIFY_OK;
 
-        ctx = blk_mq_get_ctx(q);
-        spin_lock(&ctx->lock);
-
-        while (!list_empty(&tmp)) {
-                struct request *rq;
-
-                rq = list_first_entry(&tmp, struct request, queuelist);
-                rq->mq_ctx = ctx;
-                list_move_tail(&rq->queuelist, &ctx->rq_list);
-        }
-
-        hctx = q->mq_ops->map_queue(q, ctx->cpu);
-        blk_mq_hctx_mark_pending(hctx, ctx);
-
-        spin_unlock(&ctx->lock);
+        spin_lock(&hctx->lock);
+        list_splice_tail_init(&tmp, &hctx->dispatch);
+        spin_unlock(&hctx->lock);
 
         blk_mq_run_hw_queue(hctx, true);
-        blk_mq_put_ctx(ctx);
         return NOTIFY_OK;
 }