jbd: relocate assert after state lock in journal_commit_transaction()

The state lock is taken after we are doing an assert on the state
value, not before.  So we might in fact be doing an assert on a
transient value.  Ensure the state check is within the scope of
the state lock being taken.

Backport of jbd2 commit 3ca841c1
("jbd2: relocate assert after state lock in journal_commit_transaction()")
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/jbd/commit.c

@@ -340,13 +340,13 @@ void journal_commit_transaction(journal_t *journal)
 	J_ASSERT(journal->j_committing_transaction == NULL);
 
 	commit_transaction = journal->j_running_transaction;
-	J_ASSERT(commit_transaction->t_state == T_RUNNING);
 
 	trace_jbd_start_commit(journal, commit_transaction);
 	jbd_debug(1, "JBD: starting commit of transaction %d\n",
 			commit_transaction->t_tid);
 
 	spin_lock(&journal->j_state_lock);
+	J_ASSERT(commit_transaction->t_state == T_RUNNING);
 	commit_transaction->t_state = T_LOCKED;
 
 	trace_jbd_commit_locking(journal, commit_transaction);