xlog_rseek_logrec_hdr
error = xlog_rseek_logrec_hdr(log, *head_blk, *tail_blk,
found = xlog_rseek_logrec_hdr(log, first_bad, *tail_blk, 1,
error = xlog_rseek_logrec_hdr(log, *head_blk, *head_blk, 1, buffer,