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>

1 files changed, 17 insertions, 4 deletions

diff --git a/fs/ocfs2/dlm/userdlm.c b/fs/ocfs2/dlm/userdlm.c
index c3764f4744e..bac4615965f 100644
--- 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);