block: change ->make_request_fn() and users to return a queue cookie

No functional changes in this patch, but it prepares us for returning
a more useful cookie related to the IO that was queued up.

Signed-off-by: Jens Axboe <axboe@fb.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index e8130138f29d..641e5a3ed58c 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -244,4 +244,28 @@ enum rq_flag_bits {
 #define REQ_MQ_INFLIGHT		(1ULL << __REQ_MQ_INFLIGHT)
 #define REQ_NO_TIMEOUT		(1ULL << __REQ_NO_TIMEOUT)
 
+typedef unsigned int blk_qc_t;
+#define BLK_QC_T_NONE	-1U
+#define BLK_QC_T_SHIFT	16
+
+static inline bool blk_qc_t_valid(blk_qc_t cookie)
+{
+	return cookie != BLK_QC_T_NONE;
+}
+
+static inline blk_qc_t blk_tag_to_qc_t(unsigned int tag, unsigned int queue_num)
+{
+	return tag | (queue_num << BLK_QC_T_SHIFT);
+}
+
+static inline unsigned int blk_qc_t_to_queue_num(blk_qc_t cookie)
+{
+	return cookie >> BLK_QC_T_SHIFT;
+}
+
+static inline unsigned int blk_qc_t_to_tag(blk_qc_t cookie)
+{
+	return cookie & 0xffff;
+}
+
 #endif /* __LINUX_BLK_TYPES_H */