EXT_FIRST_EXTENT
curpath->ep_index->ei_blk = EXT_FIRST_EXTENT(path[0].ep_header)->e_blk;
if (ex != EXT_FIRST_EXTENT(eh))
path[depth].ep_ext = EXT_FIRST_EXTENT(eh);
while (ex >= EXT_FIRST_EXTENT(eh) && ex_blk + ex_len > start) {
if (ex == EXT_FIRST_EXTENT(eh))
struct ext4_extent *ext = EXT_FIRST_EXTENT(eh);
l = EXT_FIRST_EXTENT(eh) + 1;
r = EXT_FIRST_EXTENT(eh) + le16toh(eh->eh_ecount) - 1;
ex = EXT_FIRST_EXTENT(neh);
#define EXT_LAST_EXTENT(hdr) (EXT_FIRST_EXTENT((hdr)) + le16toh((hdr)->eh_ecount) - 1)
#define EXT_MAX_EXTENT(hdr) (EXT_FIRST_EXTENT(hdr) + le16toh((hdr)->eh_max) - 1)