BLKG_IOSTAT_WRITE
tmp.ios[BLKG_IOSTAT_WRITE] +=
tmp.bytes[BLKG_IOSTAT_WRITE] +=
wbytes = bis->cur.bytes[BLKG_IOSTAT_WRITE];
wios = bis->cur.ios[BLKG_IOSTAT_WRITE];
return BLKG_IOSTAT_WRITE;