From 7edc46205dfddf1173a9b1a548aeac33441d0f6f Mon Sep 17 00:00:00 2001
From: Adam Kupczyk <akupczyk@ibm.com>
Date: Thu, 25 Sep 2025 05:13:28 -0400
Subject: [PATCH] extblkdev/fcm: derr when FCM and no block device discard

Add derr message when FCM is in use but discard is not enabled.

Signed-off-by: Adam Kupczyk <akupczyk@ibm.com>
(cherry picked from commit 9c0c40cfa697a905151305b2f79bfe65ca9366c7)
---
 src/extblkdev/fcm/ExtBlkDevPluginFcm.cc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/extblkdev/fcm/ExtBlkDevPluginFcm.cc b/src/extblkdev/fcm/ExtBlkDevPluginFcm.cc
index 06ef9ecefb8..33153d60f26 100644
--- a/src/extblkdev/fcm/ExtBlkDevPluginFcm.cc
+++ b/src/extblkdev/fcm/ExtBlkDevPluginFcm.cc
@@ -426,6 +426,10 @@ public:
     if (r != 0) {
       delete fcm;
       return r;
+    } else {
+      if (!cct->_conf->bdev_enable_discard) {
+        derr << "FCM device in use, but bdev_enable_discard not enabled. Free space will leak." << dendl;
+      }
     }
     ext_blk_dev.reset(fcm);
     return 0;
-- 
2.47.3