RFC] [PATCH] helper function for retrieving scsi_cmd given host based block layer tag

David C Somayajulu
2006-09-19T23:56:41Z

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>

---

block/ll_rw_blk.c | 7 +------
include/linux/blkdev.h | 8 ++++++++
include/scsi/scsi_tcq.h | 20 ++++++++++++++++++++
3 files changed, 29 insertions(+), 6 deletions(-)

39a4a2005c490d22a3e5c4430e5e71375615de73
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 556a3d3..4aea565 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -837,12 +837,7 @@ 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/blkdev.h b/include/linux/blkdev.h
index 427b0d6..dd16ce9 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -749,6 +749,14 @@ extern long blk_congestion_wait(int rw,
extern struct blk_queue_tag *blk_init_tags(int);
extern void blk_free_tags(struct blk_queue_tag *);

+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 d04d05a..1215ffe 100644
--- a/include/scsi/scsi_tcq.h
+++ b/include/scsi/scsi_tcq.h
@@ -144,4 +144,24 @@ static inline int scsi_init_shared_tag_m
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 /* _SCSI_SCSI_TCQ_H */
--