On 05/03/2020 11:54, John Garry wrote:
From: Hannes Reinecke <hare@xxxxxxxx>
Add a host template flag 'host_tagset' so hostwide tagset can be
shared on multiple reply queues after the SCSI device's reply queue
is converted to blk-mq hw queue.
We should also change the comment about Scsi_host.nr_hw_queues in
include/scsi/scsi_host.h also, like this:
* Note: it is assumed that each hardware queue has a queue depth of
* can_queue. In other words, the total queue depth per host
-* is nr_hw_queues * can_queue.
+* is nr_hw_queues * can_queue. However, in the case of .host_tagset
+* being set, the total queue depth per host is can_queue.
Signed-off-by: Hannes Reinecke <hare@xxxxxxxx>
Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
---
drivers/scsi/scsi_lib.c | 2 ++
include/scsi/scsi_host.h | 3 +++
2 files changed, 5 insertions(+)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 610ee41fa54c..84788ccc2672 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1901,6 +1901,8 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost)
shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
shost->tag_set.flags |=
BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy);
+ if (shost->hostt->host_tagset)
+ shost->tag_set.flags |= BLK_MQ_F_TAG_HCTX_SHARED;
shost->tag_set.driver_data = shost;
return blk_mq_alloc_tag_set(&shost->tag_set);
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index f577647bf5f2..4fd0af0883dd 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -429,6 +429,9 @@ struct scsi_host_template {
/* True if the low-level driver supports blk-mq only */
unsigned force_blk_mq:1;
+ /* True if the host uses host-wide tagspace */
+ unsigned host_tagset:1;
+
/*
* Countdown for host blocking with no commands outstanding.
*/
