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[RFC,v7,08/12] scsi: Add template flag 'host_tagset'

Message ID 1591810159-240929-9-git-send-email-john.garry@huawei.com
State New
Headers show
Series blk-mq/scsi: Provide hostwide shared tags for SCSI HBAs | expand

Commit Message

John Garry June 10, 2020, 5:29 p.m. UTC 
From: Hannes Reinecke <hare@suse.com>


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.

Signed-off-by: Hannes Reinecke <hare@suse.com>

jpg: Update comment on can_queue
Signed-off-by: John Garry <john.garry@huawei.com>

---
 drivers/scsi/scsi_lib.c  | 2 ++
 include/scsi/scsi_host.h | 6 +++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

-- 
2.26.2
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Patch

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 0ba7a65e7c8d..0652acdcec22 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1894,6 +1894,8 @@  int scsi_mq_setup_tags(struct Scsi_Host *shost)
 	tag_set->flags |=
 		BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy);
 	tag_set->driver_data = shost;
+	if (shost->hostt->host_tagset)
+		tag_set->flags |= BLK_MQ_F_TAG_HCTX_SHARED;
 
 	return blk_mq_alloc_tag_set(tag_set);
 }
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 46ef8cccc982..9b7e333a681d 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -436,6 +436,9 @@  struct scsi_host_template {
 	/* True if the controller does not support WRITE SAME */
 	unsigned no_write_same:1;
 
+	/* True if the host uses host-wide tagspace */
+	unsigned host_tagset:1;
+
 	/*
 	 * Countdown for host blocking with no commands outstanding.
 	 */
@@ -603,7 +606,8 @@  struct Scsi_Host {
 	 *
 	 * 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, for when host_tagset is set,
+	 * the total queue depth is can_queue.
 	 */
 	unsigned nr_hw_queues;
 	unsigned active_mode:2;