[PATCH 1/4] nvme: update the explanation for not updating the limits in nvme_config_discard

Christoph Hellwig
2023-12-26T08:59:01Z

Expeand the comment a bit to explain what is going on.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/nvme/host/core.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index d144d1acb09a05..56107cfc97b7bc 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1743,7 +1743,13 @@ static void nvme_config_discard(struct nvme_ctrl *ctrl, struct gendisk *disk,

queue->limits.discard_granularity = size;

- /* If discard is already enabled, don't reset queue limits */
+ /*
+ * If discard is already enabled, don't reset queue limits.
+ *
+ * This works around the fact that the block layer can't cope well with
+ * updating the hardware limits when overridden through sysfs. This is
+ * harmless because discard limits in NVMe are purely advisory.
+ */
if (queue->limits.max_discard_sectors)
return;

--
2.39.2