kernel-lib/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 #include "kernel-lib/raid56.h"
  32
  33 /*
  34  * This is the C data type to use
  35  */
  36
  37 /* Change this from BITS_PER_LONG if there is something better... */
  38 #if BITS_PER_LONG == 64
  39 # define NBYTES(x) ((x) * 0x0101010101010101UL)
  40 # define NSIZE  8
  41 # define NSHIFT 3
  42 typedef uint64_t unative_t;
  43 #define put_unaligned_native(val,p)     put_unaligned_64((val),(p))
  44 #define get_unaligned_native(p)         get_unaligned_64((p))
  45 #else
  46 # define NBYTES(x) ((x) * 0x01010101U)
  47 # define NSIZE  4
  48 # define NSHIFT 2
  49 typedef uint32_t unative_t;
  50 #define put_unaligned_native(val,p)     put_unaligned_32((val),(p))
  51 #define get_unaligned_native(p)         get_unaligned_32((p))
  52 #endif
  53
  54 /*
  55  * These sub-operations are separate inlines since they can sometimes be
  56  * specially optimized using architecture-specific hacks.
  57  */
  58
  59 /*
  60  * The SHLBYTE() operation shifts each byte left by 1, *not*
  61  * rolling over into the next byte
  62  */
  63 static inline __attribute_const__ unative_t SHLBYTE(unative_t v)
  64 {
  65         unative_t vv;
  66
  67         vv = (v << 1) & NBYTES(0xfe);
  68         return vv;
  69 }
  70
  71 /*
  72  * The MASK() operation returns 0xFF in any byte for which the high
  73  * bit is 1, 0x00 for any byte for which the high bit is 0.
  74  */
  75 static inline __attribute_const__ unative_t MASK(unative_t v)
  76 {
  77         unative_t vv;
  78
  79         vv = v & NBYTES(0x80);
  80         vv = (vv << 1) - (vv >> 7); /* Overflow on the top bit is OK */
  81         return vv;
  82 }
  83
  84
  85 void raid6_gen_syndrome(int disks, size_t bytes, void **ptrs)
  86 {
  87         uint8_t **dptr = (uint8_t **)ptrs;
  88         uint8_t *p, *q;
  89         int d, z, z0;
  90
  91         unative_t wd0, wq0, wp0, w10, w20;
  92
  93         z0 = disks - 3;         /* Highest data disk */
  94         p = dptr[z0+1];         /* XOR parity */
  95         q = dptr[z0+2];         /* RS syndrome */
  96
  97         for ( d = 0 ; d < bytes ; d += NSIZE*1 ) {
  98                 wq0 = wp0 = get_unaligned_native(&dptr[z0][d+0*NSIZE]);
  99                 for ( z = z0-1 ; z >= 0 ; z-- ) {
 100                         wd0 = get_unaligned_native(&dptr[z][d+0*NSIZE]);
 101                         wp0 ^= wd0;
 102                         w20 = MASK(wq0);
 103                         w10 = SHLBYTE(wq0);
 104                         w20 &= NBYTES(0x1d);
 105                         w10 ^= w20;
 106                         wq0 = w10 ^ wd0;
 107                 }
 108                 put_unaligned_native(wp0, &p[d+NSIZE*0]);
 109                 put_unaligned_native(wq0, &q[d+NSIZE*0]);
 110         }
 111 }
 112
 113 static void xor_range(char *dst, const char*src, size_t size)
 114 {
 115         /* Move to DWORD aligned */
 116         while (size && ((unsigned long)dst & sizeof(unsigned long))) {
 117                 *dst++ ^= *src++;
 118                 size--;
 119         }
 120
 121         /* DWORD aligned part */
 122         while (size >= sizeof(unsigned long)) {
 123                 *(unsigned long *)dst ^= *(unsigned long *)src;
 124                 src += sizeof(unsigned long);
 125                 dst += sizeof(unsigned long);
 126                 size -= sizeof(unsigned long);
 127         }
 128         /* Remaining */
 129         while (size) {
 130                 *dst++ ^= *src++;
 131                 size--;
 132         }
 133 }
 134
 135 /*
 136  * Generate desired data/parity stripe for RAID5
 137  *
 138  * @nr_devs:    Total number of devices, including parity
 139  * @stripe_len: Stripe length
 140  * @data:       Data, with special layout:
 141  *              data[0]:         Data stripe 0
 142  *              data[nr_devs-2]: Last data stripe
 143  *              data[nr_devs-1]: RAID5 parity
 144  * @dest:       To generate which data. should follow above data layout
 145  */
 146 int raid5_gen_result(int nr_devs, size_t stripe_len, int dest, void **data)
 147 {
 148         int i;
 149         char *buf = data[dest];
 150
 151         /* Validation check */
 152         if (stripe_len <= 0 || stripe_len != BTRFS_STRIPE_LEN) {
 153                 error("invalid parameter for %s", __func__);
 154                 return -EINVAL;
 155         }
 156
 157         if (dest >= nr_devs || nr_devs < 2) {
 158                 error("invalid parameter for %s", __func__);
 159                 return -EINVAL;
 160         }
 161         /* Shortcut for 2 devs RAID5, which is just RAID1 */
 162         if (nr_devs == 2) {
 163                 memcpy(data[dest], data[1 - dest], stripe_len);
 164                 return 0;
 165         }
 166         memset(buf, 0, stripe_len);
 167         for (i = 0; i < nr_devs; i++) {
 168                 if (i == dest)
 169                         continue;
 170                 xor_range(buf, data[i], stripe_len);
 171         }
 172         return 0;
 173 }
 174
 175 /*
 176  * Raid 6 recovery code copied from kernel lib/raid6/recov.c.
 177  * With modifications:
 178  * - rename from raid6_2data_recov_intx1
 179  * - kfree/free modification for btrfs-progs
 180  */
 181 int raid6_recov_data2(int nr_devs, size_t stripe_len, int dest1, int dest2,
 182                       void **data)
 183 {
 184         u8 *p, *q, *dp, *dq;
 185         u8 px, qx, db;
 186         const u8 *pbmul;        /* P multiplier table for B data */
 187         const u8 *qmul;         /* Q multiplier table (for both) */
 188         char *zero_mem1, *zero_mem2;
 189         int ret = 0;
 190
 191         /* Early check */
 192         if (dest1 < 0 || dest1 >= nr_devs - 2 ||
 193             dest2 < 0 || dest2 >= nr_devs - 2 || dest1 >= dest2)
 194                 return -EINVAL;
 195
 196         zero_mem1 = calloc(1, stripe_len);
 197         zero_mem2 = calloc(1, stripe_len);
 198         if (!zero_mem1 || !zero_mem2) {
 199                 free(zero_mem1);
 200                 free(zero_mem2);
 201                 return -ENOMEM;
 202         }
 203
 204         p = (u8 *)data[nr_devs - 2];
 205         q = (u8 *)data[nr_devs - 1];
 206
 207         /* Compute syndrome with zero for the missing data pages
 208            Use the dead data pages as temporary storage for
 209            delta p and delta q */
 210         dp = (u8 *)data[dest1];
 211         data[dest1] = (void *)zero_mem1;
 212         data[nr_devs - 2] = dp;
 213         dq = (u8 *)data[dest2];
 214         data[dest2] = (void *)zero_mem2;
 215         data[nr_devs - 1] = dq;
 216
 217         raid6_gen_syndrome(nr_devs, stripe_len, data);
 218
 219         /* Restore pointer table */
 220         data[dest1]   = dp;
 221         data[dest2]   = dq;
 222         data[nr_devs - 2] = p;
 223         data[nr_devs - 1] = q;
 224
 225         /* Now, pick the proper data tables */
 226         pbmul = raid6_gfmul[raid6_gfexi[dest2 - dest1]];
 227         qmul  = raid6_gfmul[raid6_gfinv[raid6_gfexp[dest1]^raid6_gfexp[dest2]]];
 228
 229         /* Now do it... */
 230         while ( stripe_len-- ) {
 231                 px    = *p ^ *dp;
 232                 qx    = qmul[*q ^ *dq];
 233                 *dq++ = db = pbmul[px] ^ qx; /* Reconstructed B */
 234                 *dp++ = db ^ px; /* Reconstructed A */
 235                 p++; q++;
 236         }
 237
 238         free(zero_mem1);
 239         free(zero_mem2);
 240         return ret;
 241 }
 242
 243 /*
 244  * Raid 6 recover code copied from kernel lib/raid6/recov.c
 245  * - rename from raid6_datap_recov_intx1()
 246  * - parameter changed from faila to dest1
 247  */
 248 int raid6_recov_datap(int nr_devs, size_t stripe_len, int dest1, void **data)
 249 {
 250         u8 *p, *q, *dq;
 251         const u8 *qmul;         /* Q multiplier table */
 252         char *zero_mem;
 253
 254         p = (u8 *)data[nr_devs - 2];
 255         q = (u8 *)data[nr_devs - 1];
 256
 257         zero_mem = calloc(1, stripe_len);
 258         if (!zero_mem)
 259                 return -ENOMEM;
 260
 261         /* Compute syndrome with zero for the missing data page
 262            Use the dead data page as temporary storage for delta q */
 263         dq = (u8 *)data[dest1];
 264         data[dest1] = (void *)zero_mem;
 265         data[nr_devs - 1] = dq;
 266
 267         raid6_gen_syndrome(nr_devs, stripe_len, data);
 268
 269         /* Restore pointer table */
 270         data[dest1]   = dq;
 271         data[nr_devs - 1] = q;
 272
 273         /* Now, pick the proper data tables */
 274         qmul  = raid6_gfmul[raid6_gfinv[raid6_gfexp[dest1]]];
 275
 276         /* Now do it... */
 277         while ( stripe_len-- ) {
 278                 *p++ ^= *dq = qmul[*q ^ *dq];
 279                 q++; dq++;
 280         }
 281         return 0;
 282 }
 283
 284 /* Original raid56 recovery wrapper */
 285 int raid56_recov(int nr_devs, size_t stripe_len, u64 profile, int dest1,
 286                  int dest2, void **data)
 287 {
 288         int min_devs;
 289         int ret;
 290
 291         if (profile & BTRFS_BLOCK_GROUP_RAID5)
 292                 min_devs = 2;
 293         else if (profile & BTRFS_BLOCK_GROUP_RAID6)
 294                 min_devs = 3;
 295         else
 296                 return -EINVAL;
 297         if (nr_devs < min_devs)
 298                 return -EINVAL;
 299
 300         /* Nothing to recover */
 301         if (dest1 == -1 && dest2 == -1)
 302                 return 0;
 303
 304         /* Reorder dest1/2, so only dest2 can be -1  */
 305         if (dest1 == -1) {
 306                 dest1 = dest2;
 307                 dest2 = -1;
 308         } else if (dest2 != -1 && dest1 != -1) {
 309                 /* Reorder dest1/2, ensure dest2 > dest1 */
 310                 if (dest1 > dest2) {
 311                         int tmp;
 312
 313                         tmp = dest2;
 314                         dest2 = dest1;
 315                         dest1 = tmp;
 316                 }
 317         }
 318
 319         if (profile & BTRFS_BLOCK_GROUP_RAID5) {
 320                 if (dest2 != -1)
 321                         return 1;
 322                 return raid5_gen_result(nr_devs, stripe_len, dest1, data);
 323         }
 324
 325         /* RAID6 one dev corrupted case*/
 326         if (dest2 == -1) {
 327                 /* Regenerate P/Q */
 328                 if (dest1 == nr_devs - 1 || dest1 == nr_devs - 2) {
 329                         raid6_gen_syndrome(nr_devs, stripe_len, data);
 330                         return 0;
 331                 }
 332
 333                 /* Regerneate data from P */
 334                 return raid5_gen_result(nr_devs - 1, stripe_len, dest1, data);
 335         }
 336
 337         /* P/Q bot corrupted */
 338         if (dest1 == nr_devs - 2 && dest2 == nr_devs - 1) {
 339                 raid6_gen_syndrome(nr_devs, stripe_len, data);
 340                 return 0;
 341         }
 342
 343         /* 2 Data corrupted */
 344         if (dest2 < nr_devs - 2)
 345                 return raid6_recov_data2(nr_devs, stripe_len, dest1, dest2,
 346                                          data);
 347         /* Data and P*/
 348         if (dest2 == nr_devs - 1)
 349                 return raid6_recov_datap(nr_devs, stripe_len, dest1, data);
 350
 351         /*
 352          * Final case, Data and Q, recover data first then regenerate Q
 353          */
 354         ret = raid5_gen_result(nr_devs - 1, stripe_len, dest1, data);
 355         if (ret < 0)
 356                 return ret;
 357         raid6_gen_syndrome(nr_devs, stripe_len, data);
 358         return 0;
 359 }