LU-1389 lov: standardize lov_do_div64() usage

[fs/lustre-release.git] / lustre / include / obd_lov.h

diff --git a/lustre/include/obd_lov.h b/lustre/include/obd_lov.h
index b05ca09..9b853d0 100644 (file)
--- a/lustre/include/obd_lov.h
+++ b/lustre/include/obd_lov.h
@@ -82,6 +82,37 @@ static inline __u32 lov_mds_md_stripecnt(int ea_size, __u32 lmm_magic)
         return 0;
 }
 
+/* lov_do_div64(a, b) returns a % b, and a = a / b.
+ * The 32-bit code is LOV-specific due to knowing about stripe limits in
+ * order to reduce the divisor to a 32-bit number.  If the divisor is
+ * already a 32-bit value the compiler handles this directly. */
+#if BITS_PER_LONG > 32
+# define lov_do_div64(n,base) ({                                       \
+       uint64_t __base = (base);                                       \
+       uint64_t __rem;                                                 \
+       __rem = ((uint64_t)(n)) % __base;                               \
+       (n) = ((uint64_t)(n)) / __base;                                 \
+       __rem;                                                          \
+  })
+#else
+# define lov_do_div64(n,base) ({                                       \
+       uint64_t __rem;                                                 \
+       if ((sizeof(base) > 4) && (((base) & 0xffffffff00000000ULL) != 0)) {  \
+               int __remainder;                                              \
+               LASSERTF(!((base) & (LOV_MIN_STRIPE_SIZE - 1)), "64 bit lov " \
+                        "division %llu / %llu\n", (n), (uint64_t)(base));    \
+               __remainder = (n) & (LOV_MIN_STRIPE_SIZE - 1);          \
+               (n) >>= LOV_MIN_STRIPE_BITS;                            \
+               __rem = do_div(n, (base) >> LOV_MIN_STRIPE_BITS);       \
+               __rem <<= LOV_MIN_STRIPE_BITS;                          \
+               __rem += __remainder;                                   \
+       } else {                                                        \
+               __rem = do_div(n, base);                                \
+       }                                                               \
+       __rem;                                                          \
+  })
+#endif
+
 #define IOC_LOV_TYPE                   'g'
 #define IOC_LOV_MIN_NR                 50
 #define IOC_LOV_SET_OSC_ACTIVE         _IOWR('g', 50, long)