scsi: add a CONFIG_SCSI_MQ_DEFAULT option
Add a Kconfig option to enable the blk-mq path for SCSI by default
to ease testing and deployment in setups that know they benefit
from blk-mq.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Robert Elliott <elliott@hp.com>
Tested-by: Robert Elliott <elliott@hp.com>
diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig
index 18a3358..71b0877 100644
--- a/drivers/scsi/Kconfig
+++ b/drivers/scsi/Kconfig
@@ -45,6 +45,17 @@
default n
select NET
+config SCSI_MQ_DEFAULT
+ bool "SCSI: use blk-mq I/O path by default"
+ depends on SCSI
+ ---help---
+ This option enables the new blk-mq based I/O path for SCSI
+ devices by default. With the option the scsi_mod.use_blk_mq
+ module/boot option defaults to Y, without it to N, but it can
+ still be overriden either way.
+
+ If unsure say N.
+
config SCSI_PROC_FS
bool "legacy /proc/scsi/ support"
depends on SCSI && PROC_FS
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 1423cb1..79c77b4 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -1367,7 +1367,11 @@
module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");
+#ifdef CONFIG_SCSI_MQ_DEFAULT
+bool scsi_use_blk_mq = true;
+#else
bool scsi_use_blk_mq = false;
+#endif
module_param_named(use_blk_mq, scsi_use_blk_mq, bool, S_IWUSR | S_IRUGO);
static int __init init_scsi(void)