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-rw-r--r--block/blk-mq.h46
1 files changed, 46 insertions, 0 deletions
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 6c7c3ff5bf62..cf01f6f8c73d 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -27,6 +27,19 @@ struct blk_mq_ctx {
struct kobject kobj;
} ____cacheline_aligned_in_smp;
+/*
+ * Bits for request->gstate. The lower two bits carry MQ_RQ_* state value
+ * and the upper bits the generation number.
+ */
+enum mq_rq_state {
+ MQ_RQ_IDLE = 0,
+ MQ_RQ_IN_FLIGHT = 1,
+
+ MQ_RQ_STATE_BITS = 2,
+ MQ_RQ_STATE_MASK = (1 << MQ_RQ_STATE_BITS) - 1,
+ MQ_RQ_GEN_INC = 1 << MQ_RQ_STATE_BITS,
+};
+
void blk_mq_freeze_queue(struct request_queue *q);
void blk_mq_free_queue(struct request_queue *q);
int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr);
@@ -85,6 +98,39 @@ extern void blk_mq_rq_timed_out(struct request *req, bool reserved);
void blk_mq_release(struct request_queue *q);
+/**
+ * blk_mq_rq_state() - read the current MQ_RQ_* state of a request
+ * @rq: target request.
+ */
+static inline int blk_mq_rq_state(struct request *rq)
+{
+ return READ_ONCE(rq->gstate) & MQ_RQ_STATE_MASK;
+}
+
+/**
+ * blk_mq_rq_update_state() - set the current MQ_RQ_* state of a request
+ * @rq: target request.
+ * @state: new state to set.
+ *
+ * Set @rq's state to @state. The caller is responsible for ensuring that
+ * there are no other updaters. A request can transition into IN_FLIGHT
+ * only from IDLE and doing so increments the generation number.
+ */
+static inline void blk_mq_rq_update_state(struct request *rq,
+ enum mq_rq_state state)
+{
+ u64 old_val = READ_ONCE(rq->gstate);
+ u64 new_val = (old_val & ~MQ_RQ_STATE_MASK) | state;
+
+ if (state == MQ_RQ_IN_FLIGHT) {
+ WARN_ON_ONCE((old_val & MQ_RQ_STATE_MASK) != MQ_RQ_IDLE);
+ new_val += MQ_RQ_GEN_INC;
+ }
+
+ /* avoid exposing interim values */
+ WRITE_ONCE(rq->gstate, new_val);
+}
+
static inline struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q,
unsigned int cpu)
{