dlm: fix slow rsb search in dir recovery

The function used to find an rsb during directory
recovery was searching the single linear list of
rsb's.  This wasted a lot of time compared to
using the standard hash table to find the rsb.

Signed-off-by: David Teigland <teigland@redhat.com>

fs/dlm/lock.h

@@ -28,6 +28,9 @@ void dlm_scan_waiters(struct dlm_ls *ls);
 void dlm_scan_timeout(struct dlm_ls *ls);
 void dlm_adjust_timeouts(struct dlm_ls *ls);
 
+int dlm_search_rsb_tree(struct rb_root *tree, char *name, int len,
+			unsigned int flags, struct dlm_rsb **r_ret);
+
 int dlm_purge_locks(struct dlm_ls *ls);
 void dlm_purge_mstcpy_locks(struct dlm_rsb *r);
 void dlm_grant_after_purge(struct dlm_ls *ls);