[PATCH] nvme: fix discard support without oncs

[Keith Busch]

From: Keith Busch <kbusch at kernel.org>

The device can report discard support without setting the ONCS DSM bit.
When not set, the driver clears max_discard_size expecting it to be set
later. We don't know the size until we have the namespace format,
though, so setting it is deferred until configuring one, but the driver
was abandoning the discard settings due to that initial clearing.

Move the max_discard_size calculation above the check for a '0' discard
size.

Fixes: 1a86924e4f46475 ("nvme: fix interpretation of DMRSL")
Cc: Tom Yan <tom.ty89 at gmail.com>
Reported-by: Laurence Oberman <loberman at redhat.com>
Signed-off-by: Keith Busch <kbusch at kernel.org>
---
 drivers/nvme/host/core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 53ef028596c61..d6a9bac91a4cd 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1674,6 +1674,9 @@ static void nvme_config_discard(struct gendisk *disk, struct nvme_ns *ns)
 	struct request_queue *queue = disk->queue;
 	u32 size = queue_logical_block_size(queue);
 
+	if (ctrl->dmrsl && ctrl->dmrsl <= nvme_sect_to_lba(ns, UINT_MAX))
+		ctrl->max_discard_sectors = nvme_lba_to_sect(ns, ctrl->dmrsl);
+
 	if (ctrl->max_discard_sectors == 0) {
 		blk_queue_max_discard_sectors(queue, 0);
 		return;
@@ -1688,9 +1691,6 @@ static void nvme_config_discard(struct gendisk *disk, struct nvme_ns *ns)
 	if (queue->limits.max_discard_sectors)
 		return;
 
-	if (ctrl->dmrsl && ctrl->dmrsl <= nvme_sect_to_lba(ns, UINT_MAX))
-		ctrl->max_discard_sectors = nvme_lba_to_sect(ns, ctrl->dmrsl);
-
 	blk_queue_max_discard_sectors(queue, ctrl->max_discard_sectors);
 	blk_queue_max_discard_segments(queue, ctrl->max_discard_segments);
 
-- 
2.34.1