[PATCH 5.15 047/201] scsi: megaraid: Clear READ queue maps nr_queues

[PATCH 5.15 047/201] scsi: megaraid: Clear READ queue maps nr_queues

[Greg Kroah-Hartman]

From: Ming Lei <ming.lei@redhat.com>

[ Upstream commit 8312cd3a7b835ae3033a679e5f0014a40e7891c5 ]

The megaraid SCSI driver sets set->nr_maps as 3 if poll_queues is > 0, and
blk-mq actually initializes each map's nr_queues as nr_hw_queues.
Consequently the driver has to clear READ queue map's nr_queues, otherwise
the queue map becomes broken if poll_queues is set as non-zero.

Link: https://lore.kernel.org/r/20220706125942.528533-1-ming.lei@redhat.com
Fixes: 9e4bec5b2a23 ("scsi: megaraid_sas: mq_poll support")
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: sumit.saxena@broadcom.com
Cc: chandrakanth.patil@broadcom.com
Cc: linux-block@vger.kernel.org
Cc: Hannes Reinecke <hare@suse.de>
Reported-by: Guangwu Zhang <guazhang@redhat.com>
Tested-by: Guangwu Zhang <guazhang@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/scsi/megaraid/megaraid_sas_base.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
index bb3f78013a13..88e164e3d2ea 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -3196,6 +3196,9 @@ static int megasas_map_queues(struct Scsi_Host *shost)
 	qoff += map->nr_queues;
 	offset += map->nr_queues;
 
+	/* we never use READ queue, so can't cheat blk-mq */
+	shost->tag_set.map[HCTX_TYPE_READ].nr_queues = 0;
+
 	/* Setup Poll hctx */
 	map = &shost->tag_set.map[HCTX_TYPE_POLL];
 	map->nr_queues = instance->iopoll_q_count;
-- 
2.35.1