bcachefs: Print allocator stuck on timeout in fallocate path

same as in io_write.c, if we're waiting on the allocator for an
excessive amount of time, print what's going on
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/io_misc.c

@@ -126,7 +126,11 @@ int bch2_extent_fallocate(struct btree_trans *trans,
 
 	if (closure_nr_remaining(&cl) != 1) {
 		bch2_trans_unlock_long(trans);
-		closure_sync(&cl);
+
+		if (closure_sync_timeout(&cl, HZ * 10)) {
+			bch2_print_allocator_stuck(c);
+			closure_sync(&cl);
+		}
 	}
 
 	return ret;