diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 83425fb3c8db..c847e17e5caa 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -840,12 +840,7 @@ EXPORT_SYMBOL(blk_queue_dma_alignment);
  **/
 struct request *blk_queue_find_tag(request_queue_t *q, int tag)
 {
-	struct blk_queue_tag *bqt = q->queue_tags;
-
-	if (unlikely(bqt == NULL || tag >= bqt->real_max_depth))
-		return NULL;
-
-	return bqt->tag_index[tag];
+	return blk_map_queue_find_tag(q->queue_tags, tag);
 }
 
 EXPORT_SYMBOL(blk_queue_find_tag);
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 711c321a7011..092dbd0e7658 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -70,7 +70,8 @@ typedef void (bio_destructor_t) (struct bio *);
  * stacking drivers)
  */
 struct bio {
-	sector_t		bi_sector;
+	sector_t		bi_sector;	/* device address in 512 byte
+						   sectors */
 	struct bio		*bi_next;	/* request queue link */
 	struct block_device	*bi_bdev;
 	unsigned long		bi_flags;	/* status, command, etc */
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 1d79b8d4ca6d..26f7856ff812 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -769,6 +769,14 @@ extern struct blk_queue_tag *blk_init_tags(int);
 extern void blk_free_tags(struct blk_queue_tag *);
 extern void blk_congestion_end(int rw);
 
+static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
+						int tag)
+{
+	if (unlikely(bqt == NULL || tag >= bqt->real_max_depth))
+		return NULL;
+	return bqt->tag_index[tag];
+}
+
 extern void blk_rq_bio_prep(request_queue_t *, struct request *, struct bio *);
 extern int blkdev_issue_flush(struct block_device *, sector_t *);
 
diff --git a/include/linux/types.h b/include/linux/types.h
index 406d4ae57631..750f085fa564 100644
--- a/include/linux/types.h
+++ b/include/linux/types.h
@@ -129,8 +129,12 @@ typedef		__s64		int64_t;
 /* this is a special 64bit data type that is 8-byte aligned */
 #define aligned_u64 unsigned long long __attribute__((aligned(8)))
 
-/*
+/**
  * The type used for indexing onto a disc or disc partition.
+ *
+ * Linux always considers sectors to be 512 bytes long independently
+ * of the devices real block size.
+ *
  * If required, asm/types.h can override it and define
  * HAVE_SECTOR_T
  */
diff --git a/include/scsi/scsi_tcq.h b/include/scsi/scsi_tcq.h
index c247a28259bc..cf4c219c0b5c 100644
--- a/include/scsi/scsi_tcq.h
+++ b/include/scsi/scsi_tcq.h
@@ -144,5 +144,25 @@ static inline int scsi_init_shared_tag_map(struct Scsi_Host *shost, int depth)
 	return shost->bqt ? 0 : -ENOMEM;
 }
 
+/**
+ * scsi_host_find_tag - find the tagged command by host
+ * @shost:	pointer to scsi_host
+ * @tag:	tag of the scsi_cmnd
+ *
+ * Notes:
+ *	Only works with tags allocated by the generic blk layer.
+ **/
+static inline struct scsi_cmnd *scsi_host_find_tag(struct Scsi_Host *shost,
+						int tag)
+{
+	struct request *req;
+
+	if (tag != SCSI_NO_TAG) {
+		req = blk_map_queue_find_tag(shost->bqt, tag);
+		return req ? (struct scsi_cmnd *)req->special : NULL;
+	}
+	return NULL;
+}
+
 #endif /* CONFIG_BLOCK */
 #endif /* _SCSI_SCSI_TCQ_H */