From 9d138465f63a72e89ec0eeb9b0ef2fd0ba918709 Mon Sep 17 00:00:00 2001
From: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>
Date: Thu, 17 Apr 2025 20:34:21 +0530
Subject: [PATCH] librbd/api: fix mirror group demote

Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>
---
 src/librbd/api/Mirror.cc | 72 +++++++++++++---------------------------
 1 file changed, 23 insertions(+), 49 deletions(-)

diff --git a/src/librbd/api/Mirror.cc b/src/librbd/api/Mirror.cc
index 58d0d8e0caa..ca43cbf4b69 100644
--- a/src/librbd/api/Mirror.cc
+++ b/src/librbd/api/Mirror.cc
@@ -3444,7 +3444,6 @@ int Mirror<I>::group_demote(IoCtx& group_ioctx,
   int ret_code = 0;
   std::vector<uint64_t> snap_ids(image_ctxs.size(), CEPH_NOSNAP);
   std::vector<C_SaferCond*> on_finishes(image_ctxs.size(), nullptr);
-  C_SaferCond* on_finish;
 
   for (size_t i = 0; i < image_ctxs.size(); i++) {
     C_SaferCond* on_finish = new C_SaferCond;
@@ -3467,62 +3466,37 @@ int Mirror<I>::group_demote(IoCtx& group_ioctx,
   }
 
   std::string group_header_oid = librbd::util::group_header_name(group_id);
-  if (ret_code < 0) {
-    // undo
-    ldout(cct, 20) << "undoing group demote: " << ret_code << dendl;
-    remove_group_snap(group_ioctx, group_id, &group_snap, &image_ctxs);
-    std::fill(snap_ids.begin(), snap_ids.end(), CEPH_NOSNAP);
-    group_snap.snaps.clear();
-    close_images(&image_ctxs);
-
-    r = prepare_group_images(group_ioctx, group_id, mirror_group.state,
-                             &image_ctxs, &group_snap, quiesce_requests,
-                             cls::rbd::MIRROR_SNAPSHOT_STATE_PRIMARY_DEMOTED,
-                             &mirror_peer_uuids,
-                             SNAP_CREATE_FLAG_SKIP_NOTIFY_QUIESCE);
-    if (r != 0) {
-      return r;
-    }
-    for (size_t i = 0; i < image_ctxs.size(); ++i) {
-      ImageCtx *ictx = image_ctxs[i];
-      ldout(cct, 20) << "promoting individual images: "
-                     << ictx->name.c_str() << dendl;
-
-      on_finish = new C_SaferCond;
-      image_promote(ictx, group_snap_id, false, &snap_ids[i], on_finish);  // No force?
-      on_finishes[i] = on_finish;
-    }
-
-    for (int i = 0, n = image_ctxs.size(); i < n; ++i) {
-      if (!on_finishes[i]) {
-        continue;
-      }
-      r = on_finishes[i]->wait();
-      delete on_finishes[i];
-      if (r < 0) {
-        lderr(cct) << "failed promoting image: " << image_ctxs[i]->name
-                   << ": " << cpp_strerror(r) << dendl;
-        // just report error, but don't abort the process
-      } else {
-        group_snap.snaps[i].snap_id = snap_ids[i];
-      }
-    }
-  }
-
   if (!ret_code) {
     group_snap.state = cls::rbd::GROUP_SNAPSHOT_STATE_COMPLETE;
     r = cls_client::group_snap_set(&group_ioctx, group_header_oid, group_snap);
     if (r < 0) {
       lderr(cct) << "failed to update group snapshot metadata: "
                  << cpp_strerror(r) << dendl;
+    } else {
+      group_unlink_peer(group_ioctx, group_id, &mirror_peer_uuids, &image_ctxs);
+
+      // mask the bit for treating the non-primary feature as read-only
+      for (size_t i = 0; i < image_ctxs.size(); ++i) {
+        ImageCtx *ictx = image_ctxs[i];
+        ictx->image_lock.lock();
+        ictx->read_only_mask |= IMAGE_READ_ONLY_FLAG_NON_PRIMARY;
+        ictx->image_lock.unlock();
+      }
     }
-    group_unlink_peer(group_ioctx, group_id, &mirror_peer_uuids, &image_ctxs);
+    ret_code = r;
   }
-  for (size_t i = 0; i < image_ctxs.size(); ++i) {
-    ImageCtx *ictx = image_ctxs[i];
-    ictx->image_lock.lock();
-    ictx->read_only_mask |= IMAGE_READ_ONLY_FLAG_NON_PRIMARY;
-    ictx->image_lock.unlock();
+
+  if (ret_code < 0) {
+    // undo
+    ldout(cct, 20) << "undoing group demote: " << ret_code << dendl;
+    remove_group_snap(group_ioctx, group_id, &group_snap, &image_ctxs);
+    // don't let the non-primary feature bit prevent image updates
+    for (size_t i = 0; i < image_ctxs.size(); ++i) {
+      ImageCtx *ictx = image_ctxs[i];
+      ictx->image_lock.lock();
+      ictx->read_only_mask &= ~IMAGE_READ_ONLY_FLAG_NON_PRIMARY;
+      ictx->image_lock.unlock();
+    }
   }
   close_images(&image_ctxs);
 
-- 
2.39.5