scsi: use host wide tags by default

This patch changes the !blk-mq path to the same defaults as the blk-mq
I/O path by always enabling block tagging, and always using host wide
tags.  We've had blk-mq available for a few releases so bugs with
this mode should have been ironed out, and this ensures we get better
coverage of over tagging setup over different configs.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

2 files changed, 20 insertions, 80 deletions

diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index e113c757d555..ed527121031d 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -406,11 +406,6 @@ struct scsi_host_template {
         int tag_alloc_policy;
 
         /*
-         * Let the block layer assigns tags to all commands.
-         */
-        unsigned use_blk_tags:1;
-
-        /*
          * Track QUEUE_FULL events and reduce queue depth on demand.
          */
         unsigned track_queue_depth:1;
diff --git a/include/scsi/scsi_tcq.h b/include/scsi/scsi_tcq.h
index b27977e8aaed..4416b1026189 100644
--- a/include/scsi/scsi_tcq.h
+++ b/include/scsi/scsi_tcq.h
@@ -10,91 +10,36 @@
 
 
 #ifdef CONFIG_BLOCK
-static inline struct scsi_cmnd *scsi_mq_find_tag(struct Scsi_Host *shost,
-                                                 int unique_tag)
-{
-        u16 hwq = blk_mq_unique_tag_to_hwq(unique_tag);
-        struct request *req = NULL;
-
-        if (hwq < shost->tag_set.nr_hw_queues)
-                req = blk_mq_tag_to_rq(shost->tag_set.tags[hwq],
-                                       blk_mq_unique_tag_to_tag(unique_tag));
-        return req ? (struct scsi_cmnd *)req->special : NULL;
-}
-
-/**
- * scsi_find_tag - find a tagged command by device
- * @SDpnt:      pointer to the ScSI device
- * @tag:        tag generated by blk_mq_unique_tag()
- *
- * Notes:
- *      Only works with tags allocated by the generic blk layer.
- **/
-static inline struct scsi_cmnd *scsi_find_tag(struct scsi_device *sdev, int tag)
-{
-        struct request *req;
-
-        if (tag != SCSI_NO_TAG) {
-                if (shost_use_blk_mq(sdev->host))
-                        return scsi_mq_find_tag(sdev->host, tag);
-
-                req = blk_queue_find_tag(sdev->request_queue, tag);
-                return req ? (struct scsi_cmnd *)req->special : NULL;
-        }
-
-        /* single command, look in space */
-        return sdev->current_cmnd;
-}
-
-
-/**
- * scsi_init_shared_tag_map - create a shared tag map
- * @shost:      the host to share the tag map among all devices
- * @depth:      the total depth of the map
- */
-static inline int scsi_init_shared_tag_map(struct Scsi_Host *shost, int depth)
-{
-        /*
-         * We always have a shared tag map around when using blk-mq.
-         */
-        if (shost_use_blk_mq(shost))
-                return 0;
-
-        /*
-         * If the shared tag map isn't already initialized, do it now.
-         * This saves callers from having to check ->bqt when setting up
-         * devices on the shared host (for libata)
-         */
-        if (!shost->bqt) {
-                shost->bqt = blk_init_tags(depth,
-                        shost->hostt->tag_alloc_policy);
-                if (!shost->bqt)
-                        return -ENOMEM;
-        }
-
-        return 0;
-}
-
 /**
  * scsi_host_find_tag - find the tagged command by host
  * @shost:      pointer to scsi_host
- * @tag:        tag generated by blk_mq_unique_tag()
+ * @tag:        tag
  *
- * Notes:
- *      Only works with tags allocated by the generic blk layer.
+ * Note: for devices using multiple hardware queues tag must have been
+ * generated by blk_mq_unique_tag().
  **/
 static inline struct scsi_cmnd *scsi_host_find_tag(struct Scsi_Host *shost,
-                                                int tag)
+                int tag)
 {
-        struct request *req;
+        struct request *req = NULL;
 
-        if (tag != SCSI_NO_TAG) {
-                if (shost_use_blk_mq(shost))
-                        return scsi_mq_find_tag(shost, tag);
+        if (tag == SCSI_NO_TAG)
+                return NULL;
+
+        if (shost_use_blk_mq(shost)) {
+                u16 hwq = blk_mq_unique_tag_to_hwq(tag);
+
+                if (hwq < shost->tag_set.nr_hw_queues) {
+                        req = blk_mq_tag_to_rq(shost->tag_set.tags[hwq],
+                                blk_mq_unique_tag_to_tag(tag));
+                }
+        } else {
                 req = blk_map_queue_find_tag(shost->bqt, tag);
-                return req ? (struct scsi_cmnd *)req->special : NULL;
         }
-        return NULL;
+
+        if (!req)
+                return NULL;
+        return req->special;
 }
 
 #endif /* CONFIG_BLOCK */