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-rw-r--r--block/blk-flush.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/block/blk-flush.c b/block/blk-flush.c
index 1002f6c58181..4201728bf3a5 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -262,6 +262,11 @@ static void flush_end_io(struct request *flush_rq, blk_status_t error)
spin_unlock_irqrestore(&fq->mq_flush_lock, flags);
}
+bool is_flush_rq(struct request *rq)
+{
+ return rq->end_io == flush_end_io;
+}
+
/**
* blk_kick_flush - consider issuing flush request
* @q: request_queue being kicked
@@ -329,6 +334,14 @@ static void blk_kick_flush(struct request_queue *q, struct blk_flush_queue *fq,
flush_rq->rq_flags |= RQF_FLUSH_SEQ;
flush_rq->rq_disk = first_rq->rq_disk;
flush_rq->end_io = flush_end_io;
+ /*
+ * Order WRITE ->end_io and WRITE rq->ref, and its pair is the one
+ * implied in refcount_inc_not_zero() called from
+ * blk_mq_find_and_get_req(), which orders WRITE/READ flush_rq->ref
+ * and READ flush_rq->end_io
+ */
+ smp_wmb();
+ refcount_set(&flush_rq->ref, 1);
blk_flush_queue_rq(flush_rq, false);
}