[PATCH v8 12/18] scsi: Add host and host template flag 'host_tagset'

John Garry
2020-08-19T15:25:41Z

From: Hannes Reinecke <hare@suse.com>

Add Host and 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.

Tested-by: Don Brace<don.brace@microsemi.com> #SCSI resv cmds patches used
Signed-off-by: Hannes Reinecke <hare@suse.com>
[jpg: Update comment on .can_queue and add Scsi_Host.host_tagset]
Signed-off-by: John Garry <john.garry@huawei.com>
---
drivers/scsi/hosts.c | 1 +
drivers/scsi/scsi_lib.c | 2 ++
include/scsi/scsi_host.h | 9 ++++++++-
3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 37d1c5565d90..2f162603876f 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -421,6 +421,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
shost->cmd_per_lun = sht->cmd_per_lun;
shost->unchecked_isa_dma = sht->unchecked_isa_dma;
shost->no_write_same = sht->no_write_same;
+ shost->host_tagset = sht->host_tagset;

if (shost_eh_deadline == -1 || !sht->eh_host_reset_handler)
shost->eh_deadline = -1;
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 7c6dd6f75190..cdef5d1777cb 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1891,6 +1891,8 @@ 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->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..701f178b20ae 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;
@@ -634,6 +638,9 @@ struct Scsi_Host {
/* The controller does not support WRITE SAME */
unsigned no_write_same:1;

+ /* True if the host uses host-wide tagspace */
+ unsigned host_tagset:1;
+
/* Host responded with short (<36 bytes) INQUIRY result */
unsigned short_inquiry:1;

--
2.26.2