ocfs2: remove an overly aggressive BUG() in dlmfs

Don't BUG() user_dlm_unblock_lock() on the absence of the USER_LOCK_BLOCKED
flag - this turns out to be a valid case. Make some of the related BUG()
statements print more useful information.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

diff --git a/fs/ocfs2/dlm/userdlm.c b/fs/ocfs2/dlm/userdlm.c
index c3764f4744ee60c9a7f6e6e2b11ff7c1fd9f48c4..bac4615965f63a87da03555baf27647d9533cab0 100644 (file)
--- a/fs/ocfs2/dlm/userdlm.c
+++ b/fs/ocfs2/dlm/userdlm.c
@@ -268,13 +268,26 @@ static void user_dlm_unblock_lock(void *opaque)
 
        spin_lock(&lockres->l_lock);
 
-       BUG_ON(!(lockres->l_flags & USER_LOCK_BLOCKED));
-       BUG_ON(!(lockres->l_flags & USER_LOCK_QUEUED));
+       mlog_bug_on_msg(!(lockres->l_flags & USER_LOCK_QUEUED),
+                       "Lockres %s, flags 0x%x\n",
+                       lockres->l_name, lockres->l_flags);
 
-       /* notice that we don't clear USER_LOCK_BLOCKED here. That's
-        * for user_ast to do. */
+       /* notice that we don't clear USER_LOCK_BLOCKED here. If it's
+        * set, we want user_ast clear it. */
        lockres->l_flags &= ~USER_LOCK_QUEUED;
 
+       /* It's valid to get here and no longer be blocked - if we get
+        * several basts in a row, we might be queued by the first
+        * one, the unblock thread might run and clear the queued
+        * flag, and finally we might get another bast which re-queues
+        * us before our ast for the downconvert is called. */
+       if (!(lockres->l_flags & USER_LOCK_BLOCKED)) {
+               mlog(0, "Lockres %s, flags 0x%x: queued but not blocking\n",
+                       lockres->l_name, lockres->l_flags);
+               spin_unlock(&lockres->l_lock);
+               goto drop_ref;
+       }
+
        if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
                mlog(0, "lock is in teardown so we do nothing\n");
                spin_unlock(&lockres->l_lock);