/* release the tag's ownership to the req cloned from */
spin_lock_irqsave(&fq->mq_flush_lock, flags);
- hctx = q->mq_ops->map_queue(q, flush_rq->mq_ctx->cpu);
+ hctx = blk_mq_map_queue(q, flush_rq->mq_ctx->cpu);
blk_mq_tag_set_rq(hctx, flush_rq->tag, fq->orig_rq);
flush_rq->tag = -1;
}
flush_rq->tag = first_rq->tag;
fq->orig_rq = first_rq;
- hctx = q->mq_ops->map_queue(q, first_rq->mq_ctx->cpu);
+ hctx = blk_mq_map_queue(q, first_rq->mq_ctx->cpu);
blk_mq_tag_set_rq(hctx, first_rq->tag, flush_rq);
}
struct request_queue *q = rq->q;
struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
+ /*
+ * Updating q->in_flight[] here for making this tag usable
+ * early. Because in blk_queue_start_tag(),
+ * q->in_flight[BLK_RW_ASYNC] is used to limit async I/O and
+ * reserve tags for sync I/O.
+ *
+ * More importantly this way can avoid the following I/O
+ * deadlock:
+ *
+ * - suppose there are 40 fua requests comming to flush queue
+ * and queue depth is 31
+ * - 30 rqs are scheduled then blk_queue_start_tag() can't alloc
+ * tag for async I/O any more
+ * - all the 30 rqs are completed before FLUSH_PENDING_TIMEOUT
+ * and flush_data_end_io() is called
+ * - the other rqs still can't go ahead if not updating
+ * q->in_flight[BLK_RW_ASYNC] here, meantime these rqs
+ * are held in flush data queue and make no progress of
+ * handling post flush rq
+ * - only after the post flush rq is handled, all these rqs
+ * can be completed
+ */
+
+ elv_completed_request(q, rq);
+
+ /* for avoiding double accounting */
+ rq->cmd_flags &= ~REQ_STARTED;
+
/*
* After populating an empty queue, kick it to avoid stall. Read
* the comment in flush_end_io().
unsigned long flags;
struct blk_flush_queue *fq = blk_get_flush_queue(q, ctx);
- hctx = q->mq_ops->map_queue(q, ctx->cpu);
+ hctx = blk_mq_map_queue(q, ctx->cpu);
/*
* After populating an empty queue, kick it to avoid stall. Read