LPERDMAP
lword = min(word + 4, LPERDMAP);
max_idx = is_ctl ? LPERCTL : LPERDMAP;
memset(&dp->wmap[0], 0, LPERDMAP * 4);
memset(&dp->pmap[0], 0, LPERDMAP * 4);
for (i = w; i < LPERDMAP; i++)
tp->nleafs = cpu_to_le32(LPERDMAP);
for (i = 0; i < LPERDMAP; i++)
__le32 wmap[LPERDMAP]; /* 1024: bits of the working map */
__le32 pmap[LPERDMAP]; /* 1024: bits of the persistent map */
#define BPERDMAP (LPERDMAP * DBWORD) /* num of blks per dmap */