[PATCH] helper function for retrieving scsi_cmd given host based block layer tag
This was necessitated by the need for a function to get back
to a scsi_cmnd, when an hba the posts its (corresponding) completion
interrupt with a block layer tag as its reference.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: David Somayajulu <david.somayajulu@qlogic.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 1d79b8d..26f7856 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -769,6 +769,14 @@
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/scsi/scsi_tcq.h b/include/scsi/scsi_tcq.h
index c247a282..cf4c219 100644
--- a/include/scsi/scsi_tcq.h
+++ b/include/scsi/scsi_tcq.h
@@ -144,5 +144,25 @@
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 */