diff options
Diffstat (limited to 'raid56.c')
| -rw-r--r-- | raid56.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/raid56.c b/raid56.c new file mode 100644 index 00000000..8c79c456 --- /dev/null +++ b/raid56.c @@ -0,0 +1,172 @@ +/* -*- linux-c -*- ------------------------------------------------------- * + * + * Copyright 2002-2004 H. Peter Anvin - All Rights Reserved + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, Inc., 53 Temple Place Ste 330, + * Boston MA 02111-1307, USA; either version 2 of the License, or + * (at your option) any later version; incorporated herein by reference. + * + * ----------------------------------------------------------------------- */ + +/* + * Added helpers for unaligned native int access + */ + +/* + * raid6int1.c + * + * 1-way unrolled portable integer math RAID-6 instruction set + * + * This file was postprocessed using unroll.pl and then ported to userspace + */ +#include <stdint.h> +#include <unistd.h> +#include "kerncompat.h" +#include "ctree.h" +#include "disk-io.h" +#include "volumes.h" +#include "utils.h" + +/* + * This is the C data type to use + */ + +/* Change this from BITS_PER_LONG if there is something better... */ +#if BITS_PER_LONG == 64 +# define NBYTES(x) ((x) * 0x0101010101010101UL) +# define NSIZE 8 +# define NSHIFT 3 +typedef uint64_t unative_t; +#define put_unaligned_native(val,p) put_unaligned_64((val),(p)) +#define get_unaligned_native(p) get_unaligned_64((p)) +#else +# define NBYTES(x) ((x) * 0x01010101U) +# define NSIZE 4 +# define NSHIFT 2 +typedef uint32_t unative_t; +#define put_unaligned_native(val,p) put_unaligned_32((val),(p)) +#define get_unaligned_native(p) get_unaligned_32((p)) +#endif + +/* + * These sub-operations are separate inlines since they can sometimes be + * specially optimized using architecture-specific hacks. + */ + +/* + * The SHLBYTE() operation shifts each byte left by 1, *not* + * rolling over into the next byte + */ +static inline __attribute_const__ unative_t SHLBYTE(unative_t v) +{ + unative_t vv; + + vv = (v << 1) & NBYTES(0xfe); + return vv; +} + +/* + * The MASK() operation returns 0xFF in any byte for which the high + * bit is 1, 0x00 for any byte for which the high bit is 0. + */ +static inline __attribute_const__ unative_t MASK(unative_t v) +{ + unative_t vv; + + vv = v & NBYTES(0x80); + vv = (vv << 1) - (vv >> 7); /* Overflow on the top bit is OK */ + return vv; +} + + +void raid6_gen_syndrome(int disks, size_t bytes, void **ptrs) +{ + uint8_t **dptr = (uint8_t **)ptrs; + uint8_t *p, *q; + int d, z, z0; + + unative_t wd0, wq0, wp0, w10, w20; + + z0 = disks - 3; /* Highest data disk */ + p = dptr[z0+1]; /* XOR parity */ + q = dptr[z0+2]; /* RS syndrome */ + + for ( d = 0 ; d < bytes ; d += NSIZE*1 ) { + wq0 = wp0 = get_unaligned_native(&dptr[z0][d+0*NSIZE]); + for ( z = z0-1 ; z >= 0 ; z-- ) { + wd0 = get_unaligned_native(&dptr[z][d+0*NSIZE]); + wp0 ^= wd0; + w20 = MASK(wq0); + w10 = SHLBYTE(wq0); + w20 &= NBYTES(0x1d); + w10 ^= w20; + wq0 = w10 ^ wd0; + } + put_unaligned_native(wp0, &p[d+NSIZE*0]); + put_unaligned_native(wq0, &q[d+NSIZE*0]); + } +} + +static void xor_range(char *dst, const char*src, size_t size) +{ + /* Move to DWORD aligned */ + while (size && ((unsigned long)dst & sizeof(unsigned long))) { + *dst++ ^= *src++; + size--; + } + + /* DWORD aligned part */ + while (size >= sizeof(unsigned long)) { + *(unsigned long *)dst ^= *(unsigned long *)src; + src += sizeof(unsigned long); + dst += sizeof(unsigned long); + size -= sizeof(unsigned long); + } + /* Remaining */ + while (size) { + *dst++ ^= *src++; + size--; + } +} + +/* + * Generate desired data/parity stripe for RAID5 + * + * @nr_devs: Total number of devices, including parity + * @stripe_len: Stripe length + * @data: Data, with special layout: + * data[0]: Data stripe 0 + * data[nr_devs-2]: Last data stripe + * data[nr_devs-1]: RAID5 parity + * @dest: To generate which data. should follow above data layout + */ +int raid5_gen_result(int nr_devs, size_t stripe_len, int dest, void **data) +{ + int i; + char *buf = data[dest]; + + /* Validation check */ + if (stripe_len <= 0 || stripe_len != BTRFS_STRIPE_LEN) { + error("invalid parameter for %s", __func__); + return -EINVAL; + } + + if (dest >= nr_devs || nr_devs < 2) { + error("invalid parameter for %s", __func__); + return -EINVAL; + } + /* Shortcut for 2 devs RAID5, which is just RAID1 */ + if (nr_devs == 2) { + memcpy(data[dest], data[1 - dest], stripe_len); + return 0; + } + memset(buf, 0, stripe_len); + for (i = 0; i < nr_devs; i++) { + if (i == dest) + continue; + xor_range(buf, data[i], stripe_len); + } + return 0; +} |