[PATCH v2] nvme: fix interpretation of dmrsl

[Tom Yan]

dmrsl is in the unit of logical block, while max_discard_sectors is
in the unit of "linux sector".

Signed-off-by: Tom Yan <tom.ty89 at gmail.com>
---
v2: ignore dmrsl if its sector-equivalent is larger than UINT_MAX
---
 drivers/nvme/host/core.c | 8 ++++++--
 drivers/nvme/host/nvme.h | 1 +
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index efb85c6d8e2d..9d2f32739a15 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1622,6 +1622,11 @@ static void nvme_config_discard(struct gendisk *disk, struct nvme_ns *ns)
 	if (blk_queue_flag_test_and_set(QUEUE_FLAG_DISCARD, queue))
 		return;
 
+	int lts_shift = ilog2(size) - 9;
+
+	if (ctrl->dmrsl && ctrl->dmrsl <= UINT_MAX >> lts_shift)
+		ctrl->max_discard_sectors = ctrl->dmrsl << lts_shift;
+
 	blk_queue_max_discard_sectors(queue, ctrl->max_discard_sectors);
 	blk_queue_max_discard_segments(queue, ctrl->max_discard_segments);
 
@@ -2881,8 +2886,7 @@ static int nvme_init_non_mdts_limits(struct nvme_ctrl *ctrl)
 
 	if (id->dmrl)
 		ctrl->max_discard_segments = id->dmrl;
-	if (id->dmrsl)
-		ctrl->max_discard_sectors = le32_to_cpu(id->dmrsl);
+	ctrl->dmrsl = le32_to_cpu(id->dmrsl);
 	if (id->wzsl)
 		ctrl->max_zeroes_sectors = nvme_mps_to_sectors(ctrl, id->wzsl);
 
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 1393bbf82d71..1c85edcf7dbb 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -279,6 +279,7 @@ struct nvme_ctrl {
 #endif
 	u16 crdt[3];
 	u16 oncs;
+	u32 dmrsl;
 	u16 oacs;
 	u16 sqsize;
 	u32 max_namespaces;
-- 
2.35.2