6785 nfs4_attr_cache deadlock

*** 2573,2586 ****
           * decrement.
           */
          ASSERT(osp->os_ref_count >= 2);
          osp->os_ref_count--;
  
!         if (!ep->error)
                  nfs4_attr_cache(vp,
                      &res.array[1].nfs_resop4_u.opgetattr.ga_res,
                      t, cred_otw, TRUE, NULL);
  
          NFS4_DEBUG(nfs4_client_state_debug, (CE_NOTE, "nfs4close_otw:"
              " returning %d", ep->error));
  
          (void) xdr_free(xdr_COMPOUND4res_clnt, (caddr_t)&res);
--- 2573,2596 ----
           * decrement.
           */
          ASSERT(osp->os_ref_count >= 2);
          osp->os_ref_count--;
  
!         if (ep->error == 0) {
!                 /*
!                  * Avoid a deadlock with the r_serial thread waiting for
!                  * os_sync_lock in nfs4_get_otw_cred_by_osp() which might be
!                  * held by us. We will wait in nfs4_attr_cache() for the
!                  * completion of the r_serial thread.
!                  */
!                 mutex_exit(&osp->os_sync_lock);
!                 *have_sync_lockp = 0;
! 
                  nfs4_attr_cache(vp,
                      &res.array[1].nfs_resop4_u.opgetattr.ga_res,
                      t, cred_otw, TRUE, NULL);
+         }
  
          NFS4_DEBUG(nfs4_client_state_debug, (CE_NOTE, "nfs4close_otw:"
              " returning %d", ep->error));
  
          (void) xdr_free(xdr_COMPOUND4res_clnt, (caddr_t)&res);