jbd: do not try lock_acquire after handle made invalid

This likely fixes the oops in __lock_acquire reported as:

http://www.kerneloops.org/raw.php?rawid=2753&msgid=
http://www.kerneloops.org/raw.php?rawid=2749&msgid=

In these reported oopses, start_this_handle is returning -EROFS.
Signed-off-by: Jonas Bonn <jonas.bonn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/jbd/transaction.c

@@ -288,10 +288,12 @@ handle_t *journal_start(journal_t *journal, int nblocks)
 		jbd_free_handle(handle);
 		current->journal_info = NULL;
 		handle = ERR_PTR(err);
+		goto out;
 	}
 
 	lock_acquire(&handle->h_lockdep_map, 0, 0, 0, 2, _THIS_IP_);
 
+out:
 	return handle;
 }