blk-mq: let blk_mq_tag_to_rq() take blk_mq_tags as the main parameter

We currently pass in the hardware queue, and get the tags from there.
But from scsi-mq, with a shared tag space, it's a lot more convenient
to pass in the blk_mq_tags instead as the hardware queue isn't always
directly available. So instead of having to re-map to a given
hardware queue from rq->mq_ctx, just pass in the tags structure.

Signed-off-by: Jens Axboe <axboe@fb.com>

3 files changed, 16 insertions, 9 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 4e8e8cf00815..4e4cd6208052 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -529,15 +529,20 @@ void blk_mq_kick_requeue_list(struct request_queue *q)
 }
 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
 
-struct request *blk_mq_tag_to_rq(struct blk_mq_hw_ctx *hctx, unsigned int tag)
+static inline bool is_flush_request(struct request *rq, unsigned int tag)
 {
-        struct request_queue *q = hctx->queue;
+        return ((rq->cmd_flags & REQ_FLUSH_SEQ) &&
+                        rq->q->flush_rq->tag == tag);
+}
 
-        if ((q->flush_rq->cmd_flags & REQ_FLUSH_SEQ) &&
-            q->flush_rq->tag == tag)
-                return q->flush_rq;
+struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
+{
+        struct request *rq = tags->rqs[tag];
+
+        if (!is_flush_request(rq, tag))
+                return rq;
 
-        return hctx->tags->rqs[tag];
+        return rq->q->flush_rq;
 }
 EXPORT_SYMBOL(blk_mq_tag_to_rq);
 
@@ -566,7 +571,7 @@ static void blk_mq_timeout_check(void *__data, unsigned long *free_tags)
                 if (tag >= hctx->tags->nr_tags)
                         break;
 
-                rq = blk_mq_tag_to_rq(hctx, tag++);
+                rq = blk_mq_tag_to_rq(hctx->tags, tag++);
                 if (rq->q != hctx->queue)
                         continue;
                 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
index abc858b3528b..74abd49fabdc 100644
--- a/drivers/block/mtip32xx/mtip32xx.c
+++ b/drivers/block/mtip32xx/mtip32xx.c
@@ -193,7 +193,9 @@ static void mtip_put_int_command(struct driver_data *dd, struct mtip_cmd *cmd)
 static struct request *mtip_rq_from_tag(struct driver_data *dd,
                                         unsigned int tag)
 {
-        return blk_mq_tag_to_rq(dd->queue->queue_hw_ctx[0], tag);
+        struct blk_mq_hw_ctx *hctx = dd->queue->queue_hw_ctx[0];
+
+        return blk_mq_tag_to_rq(hctx->tags, tag);
 }
 
 static struct mtip_cmd *mtip_cmd_from_tag(struct driver_data *dd,
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index c15128833100..0feedebfde48 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -155,7 +155,7 @@ void blk_mq_free_request(struct request *rq);
 bool blk_mq_can_queue(struct blk_mq_hw_ctx *);
 struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
                 gfp_t gfp, bool reserved);
-struct request *blk_mq_tag_to_rq(struct blk_mq_hw_ctx *hctx, unsigned int tag);
+struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag);
 
 struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *, const int ctx_index);
 struct blk_mq_hw_ctx *blk_mq_alloc_single_hw_queue(struct blk_mq_tag_set *, unsigned int, int);