GFS2: ignore unlock failures after withdraw

After gfs2 has withdrawn the filesystem, it may still have many locks not
in the unlocked state.  If it is using lock_dlm, it will failed trying
the unlocks since it has already unmounted the lock manager. Instead, it
should set the SDF_SKIP_DLM_UNLOCK flag on withdraw, to signal that
it can skip the lock_manager on unlocks, and failback to lock_nolock
style unlocking.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>

fs/gfs2/util.c

@@ -68,6 +68,7 @@ int gfs2_lm_withdraw(struct gfs2_sbd *sdp, const char *fmt, ...)
 			fs_err(sdp, "telling LM to unmount\n");
 			lm->lm_unmount(sdp);
 		}
+		set_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags);
 		fs_err(sdp, "withdrawn\n");
 		dump_stack();
 	}