librbd: exclusive lock might be disabled while waiting to acquire lock

Disabling exclusive lock will now acquire the exclusive lock before
proceeding.  If this resulted in another client releasing the lock
and re-requesting it, support for exclusive locking might be disabled
while a request is pending.

Signed-off-by: Jason Dillaman <dillaman@redhat.com>

diff --git a/src/librbd/ExclusiveLock.cc b/src/librbd/ExclusiveLock.cc
index 82d00425e0bd89699a7ab0047496d6330f309439..4c0ebfef4fab1379409889fb487cc9ad5370b67a 100644 (file)
--- a/src/librbd/ExclusiveLock.cc
+++ b/src/librbd/ExclusiveLock.cc
@@ -104,9 +104,14 @@ template <typename I>
 void ExclusiveLock<I>::shut_down(Context *on_shut_down) {
   ldout(m_image_ctx.cct, 10) << this << " " << __func__ << dendl;
 
-  Mutex::Locker locker(m_lock);
-  assert(!is_shutdown());
-  execute_action(ACTION_SHUT_DOWN, on_shut_down);
+  {
+    Mutex::Locker locker(m_lock);
+    assert(!is_shutdown());
+    execute_action(ACTION_SHUT_DOWN, on_shut_down);
+  }
+
+  // if stalled in request state machine -- abort
+  handle_lock_released();
 }
 
 template <typename I>

diff --git a/src/librbd/ImageWatcher.cc b/src/librbd/ImageWatcher.cc
index 9579723b2271091a4ccc10e2cc42c5a3ac22881a..df8f366520d45aa67108fb804760adec8dd35c94 100644 (file)
--- a/src/librbd/ImageWatcher.cc
+++ b/src/librbd/ImageWatcher.cc
@@ -417,8 +417,11 @@ void ImageWatcher::handle_request_lock(int r) {
   RWLock::RLocker owner_locker(m_image_ctx.owner_lock);
   RWLock::RLocker snap_locker(m_image_ctx.snap_lock);
 
-  // ExclusiveLock state machine cannot transition
-  assert(!m_image_ctx.exclusive_lock->is_lock_owner());
+  // ExclusiveLock state machine cannot transition -- but can be
+  // dynamically disabled
+  if (m_image_ctx.exclusive_lock == nullptr) {
+    return;
+  }
 
   if (r == -ETIMEDOUT) {
     ldout(m_image_ctx.cct, 5) << this << " timed out requesting lock: retrying"