From: Mike Snitzer This reverts commit f3002134158092178be81339ec5a22ff80e6c308. div64_u64_rem was removed because there were no other users. But Device Mapper's I/O statistics support has a need for div64_u64_rem; reintroduce this helper. Signed-off-by: Mike Snitzer Cc: Stanislaw Gruszka Cc: Frederic Weisbecker Cc: Ingo Molnar Signed-off-by: Alasdair G Kergon --- include/linux/math64.h | 19 ++++++++++++++++++- lib/div64.c | 19 +++++++++++++------ 2 files changed, 31 insertions(+), 7 deletions(-) Index: linux/include/linux/math64.h =================================================================== --- linux.orig/include/linux/math64.h +++ linux/include/linux/math64.h @@ -31,6 +31,15 @@ static inline s64 div_s64_rem(s64 divide } /** + * div64_u64_rem - unsigned 64bit divide with 64bit divisor + */ +static inline u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder) +{ + *remainder = dividend % divisor; + return dividend / divisor; +} + +/** * div64_u64 - unsigned 64bit divide with 64bit divisor */ static inline u64 div64_u64(u64 dividend, u64 divisor) @@ -63,8 +72,16 @@ static inline u64 div_u64_rem(u64 divide extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder); #endif +#ifndef div64_u64_rem +extern u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder); +#endif + #ifndef div64_u64 -extern u64 div64_u64(u64 dividend, u64 divisor); +static inline u64 div64_u64(u64 dividend, u64 divisor) +{ + u64 remainder; + return div64_u64_rem(dividend, divisor, &remainder); +} #endif #ifndef div64_s64 Index: linux/lib/div64.c =================================================================== --- linux.orig/lib/div64.c +++ linux/lib/div64.c @@ -79,9 +79,10 @@ EXPORT_SYMBOL(div_s64_rem); #endif /** - * div64_u64 - unsigned 64bit divide with 64bit divisor + * div64_u64_rem - unsigned 64bit divide with 64bit divisor and 64bit remainder * @dividend: 64bit dividend * @divisor: 64bit divisor + * @remainder: 64bit remainder * * This implementation is a modified version of the algorithm proposed * by the book 'Hacker's Delight'. The original source and full proof @@ -89,27 +90,33 @@ EXPORT_SYMBOL(div_s64_rem); * * 'http://www.hackersdelight.org/HDcode/newCode/divDouble.c.txt' */ -#ifndef div64_u64 -u64 div64_u64(u64 dividend, u64 divisor) +#ifndef div64_u64_rem +u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder) { u32 high = divisor >> 32; u64 quot; if (high == 0) { - quot = div_u64(dividend, divisor); + u32 rem32; + quot = div_u64_rem(dividend, divisor, &rem32); + *remainder = rem32; } else { int n = 1 + fls(high); quot = div_u64(dividend >> n, divisor >> n); if (quot != 0) quot--; - if ((dividend - quot * divisor) >= divisor) + + *remainder = dividend - quot * divisor; + if (*remainder >= divisor) { quot++; + *remainder -= divisor; + } } return quot; } -EXPORT_SYMBOL(div64_u64); +EXPORT_SYMBOL(div64_u64_rem); #endif /**