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-rw-r--r--block/blk-mq.c39
1 files changed, 39 insertions, 0 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index dcb467369999..097ca3ece716 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -914,6 +914,45 @@ void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
}
EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
+struct dispatch_rq_data {
+ struct blk_mq_hw_ctx *hctx;
+ struct request *rq;
+};
+
+static bool dispatch_rq_from_ctx(struct sbitmap *sb, unsigned int bitnr,
+ void *data)
+{
+ struct dispatch_rq_data *dispatch_data = data;
+ struct blk_mq_hw_ctx *hctx = dispatch_data->hctx;
+ struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
+
+ spin_lock(&ctx->lock);
+ if (unlikely(!list_empty(&ctx->rq_list))) {
+ dispatch_data->rq = list_entry_rq(ctx->rq_list.next);
+ list_del_init(&dispatch_data->rq->queuelist);
+ if (list_empty(&ctx->rq_list))
+ sbitmap_clear_bit(sb, bitnr);
+ }
+ spin_unlock(&ctx->lock);
+
+ return !dispatch_data->rq;
+}
+
+struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx,
+ struct blk_mq_ctx *start)
+{
+ unsigned off = start ? start->index_hw : 0;
+ struct dispatch_rq_data data = {
+ .hctx = hctx,
+ .rq = NULL,
+ };
+
+ __sbitmap_for_each_set(&hctx->ctx_map, off,
+ dispatch_rq_from_ctx, &data);
+
+ return data.rq;
+}
+
static inline unsigned int queued_to_index(unsigned int queued)
{
if (!queued)