From 194605d45dcb511983caca699d81855693b25fe0 Mon Sep 17 00:00:00 2001 From: Mike Christie Date: Wed, 27 Sep 2023 21:09:01 -0500 Subject: scsi: target: Have drivers report if they support direct submissions In some cases, like with multiple LUN targets or where the target has to respond to transport level requests from the receiving context it can be better to defer cmd submission to a helper thread. If the backend driver blocks on something like request/tag allocation it can block the entire target submission path and other LUs and transport IO on that session. In other cases like single LUN targets with storage that can support all the commands that the target can queue, then it's best to submit the cmd to the backend from the target's cmd receiving context. Subsequent commits will allow the user to config what they prefer, but drivers like loop can't directly submit because they can be called from a context that can't sleep. And, drivers like vhost-scsi can support direct submission, but need to keep their default behavior of deferring execution to avoid possible regressions where the backend can block. Make the drivers tell LIO core if they support direct submissions and their current default, so we can prevent users from misconfiguring the system and initialize devices correctly. Signed-off-by: Mike Christie Link: https://lore.kernel.org/r/20230928020907.5730-2-michael.christie@oracle.com Signed-off-by: Martin K. Petersen --- drivers/xen/xen-scsiback.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/xen') diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c index 8b77e4c06e43..0c51edfd13dc 100644 --- a/drivers/xen/xen-scsiback.c +++ b/drivers/xen/xen-scsiback.c @@ -1832,6 +1832,9 @@ static const struct target_core_fabric_ops scsiback_ops = { .tfc_wwn_attrs = scsiback_wwn_attrs, .tfc_tpg_base_attrs = scsiback_tpg_attrs, .tfc_tpg_param_attrs = scsiback_param_attrs, + + .default_submit_type = TARGET_DIRECT_SUBMIT, + .direct_submit_supp = 1, }; static const struct xenbus_device_id scsiback_ids[] = { -- cgit v1.2.3