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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Niklas Cassel <niklas.cassel@wdc.com>,
        Christoph Hellwig <hch@lst.de>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 165/244] nvme-pci: dont simple map sgl when sgls are disabled
Date:   Wed, 12 May 2021 16:48:56 +0200
Message-Id: <20210512144748.289616592@linuxfoundation.org>
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From: Niklas Cassel <niklas.cassel@wdc.com>

[ 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>
---
 drivers/nvme/host/pci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 3bee3724e9fa..2cb2ead7615b 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);
-- 
2.30.2