nvme: Print capabilities changes just once

This current dev_info() could be very verbose and being printed very
frequently depending on some userspace application sending some specific
commands.

Just print this message once and skip it until the controller resets.
Use a controller flag (NVME_CTRL_DIRTY_CAPABILITY) to track if the
capability needs a reset.

Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>

Author: leitao

drivers/nvme/host/core.c

@@ -1125,8 +1125,11 @@ void nvme_passthru_end(struct nvme_ctrl *ctrl, u32 effects,
 		mutex_unlock(&ctrl->scan_lock);
 	}
 	if (effects & NVME_CMD_EFFECTS_CCC) {
-		dev_info(ctrl->device,
+		if (!test_and_set_bit(NVME_CTRL_DIRTY_CAPABILITY,
+				      &ctrl->flags)) {
+			dev_info(ctrl->device,
 "controller capabilities changed, reset may be required to take effect.\n");
+		}
 	}
 	if (effects & (NVME_CMD_EFFECTS_NIC | NVME_CMD_EFFECTS_NCC)) {
 		nvme_queue_scan(ctrl);
@@ -3280,6 +3283,7 @@ int nvme_init_ctrl_finish(struct nvme_ctrl *ctrl, bool was_suspended)
 			return ret;
 	}
 
+	clear_bit(NVME_CTRL_DIRTY_CAPABILITY, &ctrl->flags);
 	ctrl->identified = true;
 
 	return 0;

drivers/nvme/host/nvme.h

@@ -243,6 +243,7 @@ enum nvme_ctrl_flags {
 	NVME_CTRL_STARTED_ONCE		= 2,
 	NVME_CTRL_STOPPED		= 3,
 	NVME_CTRL_SKIP_ID_CNS_CS	= 4,
+	NVME_CTRL_DIRTY_CAPABILITY	= 5,
 };
 
 struct nvme_ctrl {