blk_get_request() allocates a reserved tag if BLK_MQ_REQ_RESERVED has been
set in its third argument and a regular tag if that flag has not been set.
Make it possible for SCSI LLDs to mark a subset of the blk-mq tags as
'reserved'.
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Yaniv Gardi <ygardi@xxxxxxxxxxxxxx>
Cc: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>
Cc: Stanley Chu <stanley.chu@xxxxxxxxxxxx>
Cc: Avri Altman <avri.altman@xxxxxxx>
Cc: Tomas Winkler <tomas.winkler@xxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
drivers/scsi/scsi_lib.c | 1 +
include/scsi/scsi_host.h | 2 ++
2 files changed, 3 insertions(+)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 2563b061f56b..b9ac7a93aafd 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1894,6 +1894,7 @@ 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->reserved_tags;
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 fccdf84ec7e2..abf1f0e59919 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -612,6 +612,8 @@ struct Scsi_Host {
* is nr_hw_queues * can_queue.
*/
unsigned nr_hw_queues;
+ /* Number of tags that blk_mq_init_queue() should consider reserved. */
+ unsigned reserved_tags;
unsigned active_mode:2;
unsigned unchecked_isa_dma:1;
--
2.24.0.rc1.363.gb1bccd3e3d-goog
