From: Niklas Cassel <niklas.cassel@wdc.com>
Date: Fri, 9 Apr 2021 18:12:55 +0000 (+0200)
Subject: nvme-pci: don't simple map sgl when sgls are disabled
X-Git-Tag: v5.4.119~79
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=ff386ac0509823193d8f80069658d34cd4347c14;p=users%2Fdwmw2%2Flinux.git

nvme-pci: don't simple map sgl when sgls are disabled

[ Upstream commit e51183be1fa96dc6d3cd11b3c25a0f595807315e ]

According to the module parameter description for sgl_threshold,
a value of 0 means that SGLs are disabled.

If SGLs are disabled, we should respect that, even for the case
where the request is made up of a single physical segment.

Fixes: 297910571f08 ("nvme-pci: optimize mapping single segment requests using SGLs")
Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 3bee3724e9fa7..2cb2ead7615b2 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -838,7 +838,7 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
 				return nvme_setup_prp_simple(dev, req,
 							     &cmnd->rw, &bv);
 
-			if (iod->nvmeq->qid &&
+			if (iod->nvmeq->qid && sgl_threshold &&
 			    dev->ctrl.sgls & ((1 << 0) | (1 << 1)))
 				return nvme_setup_sgl_simple(dev, req,
 							     &cmnd->rw, &bv);