[PATCH RFC v2 01/24] scsi: add 'nr_reserved_cmds' field to the SCSI host template

John Garry
2020-03-10T16:32:08Z

From: Hannes Reinecke <hare@suse.com>

Add a new field 'nr_reserved_cmds' to the SCSI host template to
instruct the block layer to set aside a tag space for reserved
commands.

Signed-off-by: Hannes Reinecke <hare@suse.com>
---
drivers/scsi/scsi_lib.c | 1 +
include/scsi/scsi_host.h | 6 ++++++
2 files changed, 7 insertions(+)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 610ee41fa54c..2967325df7a0 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1896,6 +1896,7 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost)
shost->tag_set.ops = &scsi_mq_ops_no_commit;
shost->tag_set.nr_hw_queues = shost->nr_hw_queues ? : 1;
shost->tag_set.queue_depth = shost->can_queue;
+ shost->tag_set.reserved_tags = shost->nr_reserved_cmds;
shost->tag_set.cmd_size = cmd_size;
shost->tag_set.numa_node = NUMA_NO_NODE;
shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index f577647bf5f2..3f860c8ad623 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -599,6 +599,12 @@ struct Scsi_Host {
* is nr_hw_queues * can_queue.
*/
unsigned nr_hw_queues;
+
+ /*
+ * Number of reserved commands, if any.
+ */
+ unsigned nr_reserved_cmds;
+
unsigned active_mode:2;
unsigned unchecked_isa_dma:1;

--
2.17.1