librbd: bail from schedule_request_lock() if already lock owner

Race condition may be hit if there are multiple pending locks for the
same image and pending callbacks. Abort exclusive lock process if
already exclusive lock owner.

Fixes: https://tracker.ceph.com/issues/56549
Signed-off-by: Christopher Hoffman <choffman@redhat.com>

diff --git a/src/librbd/ImageWatcher.cc b/src/librbd/ImageWatcher.cc
index f8e47a8dfd3eb90f2980b36a263282dc13ad91ae..85049fac74f9aa34727262f6367df4c6405cdafb 100644 (file)
--- a/src/librbd/ImageWatcher.cc
+++ b/src/librbd/ImageWatcher.cc
@@ -572,12 +572,11 @@ template <typename I>
 void ImageWatcher<I>::schedule_request_lock(bool use_timer, int timer_delay) {
   ceph_assert(ceph_mutex_is_locked(m_image_ctx.owner_lock));
 
-  if (m_image_ctx.exclusive_lock == nullptr) {
-    // exclusive lock dynamically disabled via image refresh
+  // see notify_request_lock()
+  if (m_image_ctx.exclusive_lock == nullptr ||
+      m_image_ctx.exclusive_lock->is_lock_owner()) {
     return;
   }
-  ceph_assert(m_image_ctx.exclusive_lock &&
-              !m_image_ctx.exclusive_lock->is_lock_owner());
 
   std::shared_lock watch_locker{this->m_watch_lock};
   if (this->is_registered(this->m_watch_lock)) {