raid56.c

   1 /* -*- linux-c -*- ------------------------------------------------------- *
   2  *
   3  *   Copyright 2002-2004 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   This program is free software; you can redistribute it and/or modify
   6  *   it under the terms of the GNU General Public License as published by
   7  *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
   8  *   Boston MA 02111-1307, USA; either version 2 of the License, or
   9  *   (at your option) any later version; incorporated herein by reference.
  10  *
  11  * ----------------------------------------------------------------------- */
  12
  13 /*
  14  * Added helpers for unaligned native int access
  15  */
  16
  17 /*
  18  * raid6int1.c
  19  *
  20  * 1-way unrolled portable integer math RAID-6 instruction set
  21  *
  22  * This file was postprocessed using unroll.pl and then ported to userspace
  23  */
  24 #include <stdint.h>
  25 #include <unistd.h>
  26 #include "kerncompat.h"
  27 #include "ctree.h"
  28 #include "disk-io.h"
  29 #include "volumes.h"
  30 #include "utils.h"
  31
  32 /*
  33  * This is the C data type to use
  34  */
  35
  36 /* Change this from BITS_PER_LONG if there is something better... */
  37 #if BITS_PER_LONG == 64
  38 # define NBYTES(x) ((x) * 0x0101010101010101UL)
  39 # define NSIZE  8
  40 # define NSHIFT 3
  41 typedef uint64_t unative_t;
  42 #define put_unaligned_native(val,p)     put_unaligned_64((val),(p))
  43 #define get_unaligned_native(p)         get_unaligned_64((p))
  44 #else
  45 # define NBYTES(x) ((x) * 0x01010101U)
  46 # define NSIZE  4
  47 # define NSHIFT 2
  48 typedef uint32_t unative_t;
  49 #define put_unaligned_native(val,p)     put_unaligned_32((val),(p))
  50 #define get_unaligned_native(p)         get_unaligned_32((p))
  51 #endif
  52
  53 /*
  54  * These sub-operations are separate inlines since they can sometimes be
  55  * specially optimized using architecture-specific hacks.
  56  */
  57
  58 /*
  59  * The SHLBYTE() operation shifts each byte left by 1, *not*
  60  * rolling over into the next byte
  61  */
  62 static inline __attribute_const__ unative_t SHLBYTE(unative_t v)
  63 {
  64         unative_t vv;
  65
  66         vv = (v << 1) & NBYTES(0xfe);
  67         return vv;
  68 }
  69
  70 /*
  71  * The MASK() operation returns 0xFF in any byte for which the high
  72  * bit is 1, 0x00 for any byte for which the high bit is 0.
  73  */
  74 static inline __attribute_const__ unative_t MASK(unative_t v)
  75 {
  76         unative_t vv;
  77
  78         vv = v & NBYTES(0x80);
  79         vv = (vv << 1) - (vv >> 7); /* Overflow on the top bit is OK */
  80         return vv;
  81 }
  82
  83
  84 void raid6_gen_syndrome(int disks, size_t bytes, void **ptrs)
  85 {
  86         uint8_t **dptr = (uint8_t **)ptrs;
  87         uint8_t *p, *q;
  88         int d, z, z0;
  89
  90         unative_t wd0, wq0, wp0, w10, w20;
  91
  92         z0 = disks - 3;         /* Highest data disk */
  93         p = dptr[z0+1];         /* XOR parity */
  94         q = dptr[z0+2];         /* RS syndrome */
  95
  96         for ( d = 0 ; d < bytes ; d += NSIZE*1 ) {
  97                 wq0 = wp0 = get_unaligned_native(&dptr[z0][d+0*NSIZE]);
  98                 for ( z = z0-1 ; z >= 0 ; z-- ) {
  99                         wd0 = get_unaligned_native(&dptr[z][d+0*NSIZE]);
 100                         wp0 ^= wd0;
 101                         w20 = MASK(wq0);
 102                         w10 = SHLBYTE(wq0);
 103                         w20 &= NBYTES(0x1d);
 104                         w10 ^= w20;
 105                         wq0 = w10 ^ wd0;
 106                 }
 107                 put_unaligned_native(wp0, &p[d+NSIZE*0]);
 108                 put_unaligned_native(wq0, &q[d+NSIZE*0]);
 109         }
 110 }
 111
 112 static void xor_range(char *dst, const char*src, size_t size)
 113 {
 114         /* Move to DWORD aligned */
 115         while (size && ((unsigned long)dst & sizeof(unsigned long))) {
 116                 *dst++ ^= *src++;
 117                 size--;
 118         }
 119
 120         /* DWORD aligned part */
 121         while (size >= sizeof(unsigned long)) {
 122                 *(unsigned long *)dst ^= *(unsigned long *)src;
 123                 src += sizeof(unsigned long);
 124                 dst += sizeof(unsigned long);
 125                 size -= sizeof(unsigned long);
 126         }
 127         /* Remaining */
 128         while (size) {
 129                 *dst++ ^= *src++;
 130                 size--;
 131         }
 132 }
 133
 134 /*
 135  * Generate desired data/parity stripe for RAID5
 136  *
 137  * @nr_devs:    Total number of devices, including parity
 138  * @stripe_len: Stripe length
 139  * @data:       Data, with special layout:
 140  *              data[0]:         Data stripe 0
 141  *              data[nr_devs-2]: Last data stripe
 142  *              data[nr_devs-1]: RAID5 parity
 143  * @dest:       To generate which data. should follow above data layout
 144  */
 145 int raid5_gen_result(int nr_devs, size_t stripe_len, int dest, void **data)
 146 {
 147         int i;
 148         char *buf = data[dest];
 149
 150         /* Validation check */
 151         if (stripe_len <= 0 || stripe_len != BTRFS_STRIPE_LEN) {
 152                 error("invalid parameter for %s", __func__);
 153                 return -EINVAL;
 154         }
 155
 156         if (dest >= nr_devs || nr_devs < 2) {
 157                 error("invalid parameter for %s", __func__);
 158                 return -EINVAL;
 159         }
 160         /* Shortcut for 2 devs RAID5, which is just RAID1 */
 161         if (nr_devs == 2) {
 162                 memcpy(data[dest], data[1 - dest], stripe_len);
 163                 return 0;
 164         }
 165         memset(buf, 0, stripe_len);
 166         for (i = 0; i < nr_devs; i++) {
 167                 if (i == dest)
 168                         continue;
 169                 xor_range(buf, data[i], stripe_len);
 170         }
 171         return 0;
 172 }