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Diffstat (limited to 'sys/contrib/opensolaris/uts/common/fs/zfs/vdev_raidz.c')
| -rw-r--r-- | sys/contrib/opensolaris/uts/common/fs/zfs/vdev_raidz.c | 1237 |
1 files changed, 1237 insertions, 0 deletions
diff --git a/sys/contrib/opensolaris/uts/common/fs/zfs/vdev_raidz.c b/sys/contrib/opensolaris/uts/common/fs/zfs/vdev_raidz.c new file mode 100644 index 0000000..0c86630 --- /dev/null +++ b/sys/contrib/opensolaris/uts/common/fs/zfs/vdev_raidz.c @@ -0,0 +1,1237 @@ +/* + * CDDL HEADER START + * + * The contents of this file are subject to the terms of the + * Common Development and Distribution License (the "License"). + * You may not use this file except in compliance with the License. + * + * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE + * or http://www.opensolaris.org/os/licensing. + * See the License for the specific language governing permissions + * and limitations under the License. + * + * When distributing Covered Code, include this CDDL HEADER in each + * file and include the License file at usr/src/OPENSOLARIS.LICENSE. + * If applicable, add the following below this CDDL HEADER, with the + * fields enclosed by brackets "[]" replaced with your own identifying + * information: Portions Copyright [yyyy] [name of copyright owner] + * + * CDDL HEADER END + */ + +/* + * Copyright 2007 Sun Microsystems, Inc. All rights reserved. + * Use is subject to license terms. + */ + +#pragma ident "%Z%%M% %I% %E% SMI" + +#include <sys/zfs_context.h> +#include <sys/spa.h> +#include <sys/vdev_impl.h> +#include <sys/zio.h> +#include <sys/zio_checksum.h> +#include <sys/fs/zfs.h> +#include <sys/fm/fs/zfs.h> + +/* + * Virtual device vector for RAID-Z. + * + * This vdev supports both single and double parity. For single parity, we + * use a simple XOR of all the data columns. For double parity, we use both + * the simple XOR as well as a technique described in "The mathematics of + * RAID-6" by H. Peter Anvin. This technique defines a Galois field, GF(2^8), + * over the integers expressable in a single byte. Briefly, the operations on + * the field are defined as follows: + * + * o addition (+) is represented by a bitwise XOR + * o subtraction (-) is therefore identical to addition: A + B = A - B + * o multiplication of A by 2 is defined by the following bitwise expression: + * (A * 2)_7 = A_6 + * (A * 2)_6 = A_5 + * (A * 2)_5 = A_4 + * (A * 2)_4 = A_3 + A_7 + * (A * 2)_3 = A_2 + A_7 + * (A * 2)_2 = A_1 + A_7 + * (A * 2)_1 = A_0 + * (A * 2)_0 = A_7 + * + * In C, multiplying by 2 is therefore ((a << 1) ^ ((a & 0x80) ? 0x1d : 0)). + * + * Observe that any number in the field (except for 0) can be expressed as a + * power of 2 -- a generator for the field. We store a table of the powers of + * 2 and logs base 2 for quick look ups, and exploit the fact that A * B can + * be rewritten as 2^(log_2(A) + log_2(B)) (where '+' is normal addition rather + * than field addition). The inverse of a field element A (A^-1) is A^254. + * + * The two parity columns, P and Q, over several data columns, D_0, ... D_n-1, + * can be expressed by field operations: + * + * P = D_0 + D_1 + ... + D_n-2 + D_n-1 + * Q = 2^n-1 * D_0 + 2^n-2 * D_1 + ... + 2^1 * D_n-2 + 2^0 * D_n-1 + * = ((...((D_0) * 2 + D_1) * 2 + ...) * 2 + D_n-2) * 2 + D_n-1 + * + * See the reconstruction code below for how P and Q can used individually or + * in concert to recover missing data columns. + */ + +typedef struct raidz_col { + uint64_t rc_devidx; /* child device index for I/O */ + uint64_t rc_offset; /* device offset */ + uint64_t rc_size; /* I/O size */ + void *rc_data; /* I/O data */ + int rc_error; /* I/O error for this device */ + uint8_t rc_tried; /* Did we attempt this I/O column? */ + uint8_t rc_skipped; /* Did we skip this I/O column? */ +} raidz_col_t; + +typedef struct raidz_map { + uint64_t rm_cols; /* Column count */ + uint64_t rm_bigcols; /* Number of oversized columns */ + uint64_t rm_asize; /* Actual total I/O size */ + uint64_t rm_missingdata; /* Count of missing data devices */ + uint64_t rm_missingparity; /* Count of missing parity devices */ + uint64_t rm_firstdatacol; /* First data column/parity count */ + raidz_col_t rm_col[1]; /* Flexible array of I/O columns */ +} raidz_map_t; + +#define VDEV_RAIDZ_P 0 +#define VDEV_RAIDZ_Q 1 + +#define VDEV_RAIDZ_MAXPARITY 2 + +#define VDEV_RAIDZ_MUL_2(a) (((a) << 1) ^ (((a) & 0x80) ? 0x1d : 0)) + +/* + * These two tables represent powers and logs of 2 in the Galois field defined + * above. These values were computed by repeatedly multiplying by 2 as above. + */ +static const uint8_t vdev_raidz_pow2[256] = { + 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, + 0x1d, 0x3a, 0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26, + 0x4c, 0x98, 0x2d, 0x5a, 0xb4, 0x75, 0xea, 0xc9, + 0x8f, 0x03, 0x06, 0x0c, 0x18, 0x30, 0x60, 0xc0, + 0x9d, 0x27, 0x4e, 0x9c, 0x25, 0x4a, 0x94, 0x35, + 0x6a, 0xd4, 0xb5, 0x77, 0xee, 0xc1, 0x9f, 0x23, + 0x46, 0x8c, 0x05, 0x0a, 0x14, 0x28, 0x50, 0xa0, + 0x5d, 0xba, 0x69, 0xd2, 0xb9, 0x6f, 0xde, 0xa1, + 0x5f, 0xbe, 0x61, 0xc2, 0x99, 0x2f, 0x5e, 0xbc, + 0x65, 0xca, 0x89, 0x0f, 0x1e, 0x3c, 0x78, 0xf0, + 0xfd, 0xe7, 0xd3, 0xbb, 0x6b, 0xd6, 0xb1, 0x7f, + 0xfe, 0xe1, 0xdf, 0xa3, 0x5b, 0xb6, 0x71, 0xe2, + 0xd9, 0xaf, 0x43, 0x86, 0x11, 0x22, 0x44, 0x88, + 0x0d, 0x1a, 0x34, 0x68, 0xd0, 0xbd, 0x67, 0xce, + 0x81, 0x1f, 0x3e, 0x7c, 0xf8, 0xed, 0xc7, 0x93, + 0x3b, 0x76, 0xec, 0xc5, 0x97, 0x33, 0x66, 0xcc, + 0x85, 0x17, 0x2e, 0x5c, 0xb8, 0x6d, 0xda, 0xa9, + 0x4f, 0x9e, 0x21, 0x42, 0x84, 0x15, 0x2a, 0x54, + 0xa8, 0x4d, 0x9a, 0x29, 0x52, 0xa4, 0x55, 0xaa, + 0x49, 0x92, 0x39, 0x72, 0xe4, 0xd5, 0xb7, 0x73, + 0xe6, 0xd1, 0xbf, 0x63, 0xc6, 0x91, 0x3f, 0x7e, + 0xfc, 0xe5, 0xd7, 0xb3, 0x7b, 0xf6, 0xf1, 0xff, + 0xe3, 0xdb, 0xab, 0x4b, 0x96, 0x31, 0x62, 0xc4, + 0x95, 0x37, 0x6e, 0xdc, 0xa5, 0x57, 0xae, 0x41, + 0x82, 0x19, 0x32, 0x64, 0xc8, 0x8d, 0x07, 0x0e, + 0x1c, 0x38, 0x70, 0xe0, 0xdd, 0xa7, 0x53, 0xa6, + 0x51, 0xa2, 0x59, 0xb2, 0x79, 0xf2, 0xf9, 0xef, + 0xc3, 0x9b, 0x2b, 0x56, 0xac, 0x45, 0x8a, 0x09, + 0x12, 0x24, 0x48, 0x90, 0x3d, 0x7a, 0xf4, 0xf5, + 0xf7, 0xf3, 0xfb, 0xeb, 0xcb, 0x8b, 0x0b, 0x16, + 0x2c, 0x58, 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83, + 0x1b, 0x36, 0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x01 +}; +static const uint8_t vdev_raidz_log2[256] = { + 0x00, 0x00, 0x01, 0x19, 0x02, 0x32, 0x1a, 0xc6, + 0x03, 0xdf, 0x33, 0xee, 0x1b, 0x68, 0xc7, 0x4b, + 0x04, 0x64, 0xe0, 0x0e, 0x34, 0x8d, 0xef, 0x81, + 0x1c, 0xc1, 0x69, 0xf8, 0xc8, 0x08, 0x4c, 0x71, + 0x05, 0x8a, 0x65, 0x2f, 0xe1, 0x24, 0x0f, 0x21, + 0x35, 0x93, 0x8e, 0xda, 0xf0, 0x12, 0x82, 0x45, + 0x1d, 0xb5, 0xc2, 0x7d, 0x6a, 0x27, 0xf9, 0xb9, + 0xc9, 0x9a, 0x09, 0x78, 0x4d, 0xe4, 0x72, 0xa6, + 0x06, 0xbf, 0x8b, 0x62, 0x66, 0xdd, 0x30, 0xfd, + 0xe2, 0x98, 0x25, 0xb3, 0x10, 0x91, 0x22, 0x88, + 0x36, 0xd0, 0x94, 0xce, 0x8f, 0x96, 0xdb, 0xbd, + 0xf1, 0xd2, 0x13, 0x5c, 0x83, 0x38, 0x46, 0x40, + 0x1e, 0x42, 0xb6, 0xa3, 0xc3, 0x48, 0x7e, 0x6e, + 0x6b, 0x3a, 0x28, 0x54, 0xfa, 0x85, 0xba, 0x3d, + 0xca, 0x5e, 0x9b, 0x9f, 0x0a, 0x15, 0x79, 0x2b, + 0x4e, 0xd4, 0xe5, 0xac, 0x73, 0xf3, 0xa7, 0x57, + 0x07, 0x70, 0xc0, 0xf7, 0x8c, 0x80, 0x63, 0x0d, + 0x67, 0x4a, 0xde, 0xed, 0x31, 0xc5, 0xfe, 0x18, + 0xe3, 0xa5, 0x99, 0x77, 0x26, 0xb8, 0xb4, 0x7c, + 0x11, 0x44, 0x92, 0xd9, 0x23, 0x20, 0x89, 0x2e, + 0x37, 0x3f, 0xd1, 0x5b, 0x95, 0xbc, 0xcf, 0xcd, + 0x90, 0x87, 0x97, 0xb2, 0xdc, 0xfc, 0xbe, 0x61, + 0xf2, 0x56, 0xd3, 0xab, 0x14, 0x2a, 0x5d, 0x9e, + 0x84, 0x3c, 0x39, 0x53, 0x47, 0x6d, 0x41, 0xa2, + 0x1f, 0x2d, 0x43, 0xd8, 0xb7, 0x7b, 0xa4, 0x76, + 0xc4, 0x17, 0x49, 0xec, 0x7f, 0x0c, 0x6f, 0xf6, + 0x6c, 0xa1, 0x3b, 0x52, 0x29, 0x9d, 0x55, 0xaa, + 0xfb, 0x60, 0x86, 0xb1, 0xbb, 0xcc, 0x3e, 0x5a, + 0xcb, 0x59, 0x5f, 0xb0, 0x9c, 0xa9, 0xa0, 0x51, + 0x0b, 0xf5, 0x16, 0xeb, 0x7a, 0x75, 0x2c, 0xd7, + 0x4f, 0xae, 0xd5, 0xe9, 0xe6, 0xe7, 0xad, 0xe8, + 0x74, 0xd6, 0xf4, 0xea, 0xa8, 0x50, 0x58, 0xaf, +}; + +/* + * Multiply a given number by 2 raised to the given power. + */ +static uint8_t +vdev_raidz_exp2(uint_t a, int exp) +{ + if (a == 0) + return (0); + + ASSERT(exp >= 0); + ASSERT(vdev_raidz_log2[a] > 0 || a == 1); + + exp += vdev_raidz_log2[a]; + if (exp > 255) + exp -= 255; + + return (vdev_raidz_pow2[exp]); +} + +static raidz_map_t * +vdev_raidz_map_alloc(zio_t *zio, uint64_t unit_shift, uint64_t dcols, + uint64_t nparity) +{ + raidz_map_t *rm; + uint64_t b = zio->io_offset >> unit_shift; + uint64_t s = zio->io_size >> unit_shift; + uint64_t f = b % dcols; + uint64_t o = (b / dcols) << unit_shift; + uint64_t q, r, c, bc, col, acols, coff, devidx; + + q = s / (dcols - nparity); + r = s - q * (dcols - nparity); + bc = (r == 0 ? 0 : r + nparity); + + acols = (q == 0 ? bc : dcols); + + rm = kmem_alloc(offsetof(raidz_map_t, rm_col[acols]), KM_SLEEP); + + rm->rm_cols = acols; + rm->rm_bigcols = bc; + rm->rm_asize = 0; + rm->rm_missingdata = 0; + rm->rm_missingparity = 0; + rm->rm_firstdatacol = nparity; + + for (c = 0; c < acols; c++) { + col = f + c; + coff = o; + if (col >= dcols) { + col -= dcols; + coff += 1ULL << unit_shift; + } + rm->rm_col[c].rc_devidx = col; + rm->rm_col[c].rc_offset = coff; + rm->rm_col[c].rc_size = (q + (c < bc)) << unit_shift; + rm->rm_col[c].rc_data = NULL; + rm->rm_col[c].rc_error = 0; + rm->rm_col[c].rc_tried = 0; + rm->rm_col[c].rc_skipped = 0; + rm->rm_asize += rm->rm_col[c].rc_size; + } + + rm->rm_asize = roundup(rm->rm_asize, (nparity + 1) << unit_shift); + + for (c = 0; c < rm->rm_firstdatacol; c++) + rm->rm_col[c].rc_data = zio_buf_alloc(rm->rm_col[c].rc_size); + + rm->rm_col[c].rc_data = zio->io_data; + + for (c = c + 1; c < acols; c++) + rm->rm_col[c].rc_data = (char *)rm->rm_col[c - 1].rc_data + + rm->rm_col[c - 1].rc_size; + + /* + * If all data stored spans all columns, there's a danger that parity + * will always be on the same device and, since parity isn't read + * during normal operation, that that device's I/O bandwidth won't be + * used effectively. We therefore switch the parity every 1MB. + * + * ... at least that was, ostensibly, the theory. As a practical + * matter unless we juggle the parity between all devices evenly, we + * won't see any benefit. Further, occasional writes that aren't a + * multiple of the LCM of the number of children and the minimum + * stripe width are sufficient to avoid pessimal behavior. + * Unfortunately, this decision created an implicit on-disk format + * requirement that we need to support for all eternity, but only + * for single-parity RAID-Z. + */ + ASSERT(rm->rm_cols >= 2); + ASSERT(rm->rm_col[0].rc_size == rm->rm_col[1].rc_size); + + if (rm->rm_firstdatacol == 1 && (zio->io_offset & (1ULL << 20))) { + devidx = rm->rm_col[0].rc_devidx; + o = rm->rm_col[0].rc_offset; + rm->rm_col[0].rc_devidx = rm->rm_col[1].rc_devidx; + rm->rm_col[0].rc_offset = rm->rm_col[1].rc_offset; + rm->rm_col[1].rc_devidx = devidx; + rm->rm_col[1].rc_offset = o; + } + + zio->io_vsd = rm; + return (rm); +} + +static void +vdev_raidz_map_free(zio_t *zio) +{ + raidz_map_t *rm = zio->io_vsd; + int c; + + for (c = 0; c < rm->rm_firstdatacol; c++) + zio_buf_free(rm->rm_col[c].rc_data, rm->rm_col[c].rc_size); + + kmem_free(rm, offsetof(raidz_map_t, rm_col[rm->rm_cols])); + zio->io_vsd = NULL; +} + +static void +vdev_raidz_generate_parity_p(raidz_map_t *rm) +{ + uint64_t *p, *src, pcount, ccount, i; + int c; + + pcount = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (src[0]); + + for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { + src = rm->rm_col[c].rc_data; + p = rm->rm_col[VDEV_RAIDZ_P].rc_data; + ccount = rm->rm_col[c].rc_size / sizeof (src[0]); + + if (c == rm->rm_firstdatacol) { + ASSERT(ccount == pcount); + for (i = 0; i < ccount; i++, p++, src++) { + *p = *src; + } + } else { + ASSERT(ccount <= pcount); + for (i = 0; i < ccount; i++, p++, src++) { + *p ^= *src; + } + } + } +} + +static void +vdev_raidz_generate_parity_pq(raidz_map_t *rm) +{ + uint64_t *q, *p, *src, pcount, ccount, mask, i; + int c; + + pcount = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (src[0]); + ASSERT(rm->rm_col[VDEV_RAIDZ_P].rc_size == + rm->rm_col[VDEV_RAIDZ_Q].rc_size); + + for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { + src = rm->rm_col[c].rc_data; + p = rm->rm_col[VDEV_RAIDZ_P].rc_data; + q = rm->rm_col[VDEV_RAIDZ_Q].rc_data; + ccount = rm->rm_col[c].rc_size / sizeof (src[0]); + + if (c == rm->rm_firstdatacol) { + ASSERT(ccount == pcount || ccount == 0); + for (i = 0; i < ccount; i++, p++, q++, src++) { + *q = *src; + *p = *src; + } + for (; i < pcount; i++, p++, q++, src++) { + *q = 0; + *p = 0; + } + } else { + ASSERT(ccount <= pcount); + + /* + * Rather than multiplying each byte individually (as + * described above), we are able to handle 8 at once + * by generating a mask based on the high bit in each + * byte and using that to conditionally XOR in 0x1d. + */ + for (i = 0; i < ccount; i++, p++, q++, src++) { + mask = *q & 0x8080808080808080ULL; + mask = (mask << 1) - (mask >> 7); + *q = ((*q << 1) & 0xfefefefefefefefeULL) ^ + (mask & 0x1d1d1d1d1d1d1d1dULL); + *q ^= *src; + *p ^= *src; + } + + /* + * Treat short columns as though they are full of 0s. + */ + for (; i < pcount; i++, q++) { + mask = *q & 0x8080808080808080ULL; + mask = (mask << 1) - (mask >> 7); + *q = ((*q << 1) & 0xfefefefefefefefeULL) ^ + (mask & 0x1d1d1d1d1d1d1d1dULL); + } + } + } +} + +static void +vdev_raidz_reconstruct_p(raidz_map_t *rm, int x) +{ + uint64_t *dst, *src, xcount, ccount, count, i; + int c; + + xcount = rm->rm_col[x].rc_size / sizeof (src[0]); + ASSERT(xcount <= rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (src[0])); + ASSERT(xcount > 0); + + src = rm->rm_col[VDEV_RAIDZ_P].rc_data; + dst = rm->rm_col[x].rc_data; + for (i = 0; i < xcount; i++, dst++, src++) { + *dst = *src; + } + + for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { + src = rm->rm_col[c].rc_data; + dst = rm->rm_col[x].rc_data; + + if (c == x) + continue; + + ccount = rm->rm_col[c].rc_size / sizeof (src[0]); + count = MIN(ccount, xcount); + + for (i = 0; i < count; i++, dst++, src++) { + *dst ^= *src; + } + } +} + +static void +vdev_raidz_reconstruct_q(raidz_map_t *rm, int x) +{ + uint64_t *dst, *src, xcount, ccount, count, mask, i; + uint8_t *b; + int c, j, exp; + + xcount = rm->rm_col[x].rc_size / sizeof (src[0]); + ASSERT(xcount <= rm->rm_col[VDEV_RAIDZ_Q].rc_size / sizeof (src[0])); + + for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { + src = rm->rm_col[c].rc_data; + dst = rm->rm_col[x].rc_data; + + if (c == x) + ccount = 0; + else + ccount = rm->rm_col[c].rc_size / sizeof (src[0]); + + count = MIN(ccount, xcount); + + if (c == rm->rm_firstdatacol) { + for (i = 0; i < count; i++, dst++, src++) { + *dst = *src; + } + for (; i < xcount; i++, dst++) { + *dst = 0; + } + + } else { + /* + * For an explanation of this, see the comment in + * vdev_raidz_generate_parity_pq() above. + */ + for (i = 0; i < count; i++, dst++, src++) { + mask = *dst & 0x8080808080808080ULL; + mask = (mask << 1) - (mask >> 7); + *dst = ((*dst << 1) & 0xfefefefefefefefeULL) ^ + (mask & 0x1d1d1d1d1d1d1d1dULL); + *dst ^= *src; + } + + for (; i < xcount; i++, dst++) { + mask = *dst & 0x8080808080808080ULL; + mask = (mask << 1) - (mask >> 7); + *dst = ((*dst << 1) & 0xfefefefefefefefeULL) ^ + (mask & 0x1d1d1d1d1d1d1d1dULL); + } + } + } + + src = rm->rm_col[VDEV_RAIDZ_Q].rc_data; + dst = rm->rm_col[x].rc_data; + exp = 255 - (rm->rm_cols - 1 - x); + + for (i = 0; i < xcount; i++, dst++, src++) { + *dst ^= *src; + for (j = 0, b = (uint8_t *)dst; j < 8; j++, b++) { + *b = vdev_raidz_exp2(*b, exp); + } + } +} + +static void +vdev_raidz_reconstruct_pq(raidz_map_t *rm, int x, int y) +{ + uint8_t *p, *q, *pxy, *qxy, *xd, *yd, tmp, a, b, aexp, bexp; + void *pdata, *qdata; + uint64_t xsize, ysize, i; + + ASSERT(x < y); + ASSERT(x >= rm->rm_firstdatacol); + ASSERT(y < rm->rm_cols); + + ASSERT(rm->rm_col[x].rc_size >= rm->rm_col[y].rc_size); + + /* + * Move the parity data aside -- we're going to compute parity as + * though columns x and y were full of zeros -- Pxy and Qxy. We want to + * reuse the parity generation mechanism without trashing the actual + * parity so we make those columns appear to be full of zeros by + * setting their lengths to zero. + */ + pdata = rm->rm_col[VDEV_RAIDZ_P].rc_data; + qdata = rm->rm_col[VDEV_RAIDZ_Q].rc_data; + xsize = rm->rm_col[x].rc_size; + ysize = rm->rm_col[y].rc_size; + + rm->rm_col[VDEV_RAIDZ_P].rc_data = + zio_buf_alloc(rm->rm_col[VDEV_RAIDZ_P].rc_size); + rm->rm_col[VDEV_RAIDZ_Q].rc_data = + zio_buf_alloc(rm->rm_col[VDEV_RAIDZ_Q].rc_size); + rm->rm_col[x].rc_size = 0; + rm->rm_col[y].rc_size = 0; + + vdev_raidz_generate_parity_pq(rm); + + rm->rm_col[x].rc_size = xsize; + rm->rm_col[y].rc_size = ysize; + + p = pdata; + q = qdata; + pxy = rm->rm_col[VDEV_RAIDZ_P].rc_data; + qxy = rm->rm_col[VDEV_RAIDZ_Q].rc_data; + xd = rm->rm_col[x].rc_data; + yd = rm->rm_col[y].rc_data; + + /* + * We now have: + * Pxy = P + D_x + D_y + * Qxy = Q + 2^(ndevs - 1 - x) * D_x + 2^(ndevs - 1 - y) * D_y + * + * We can then solve for D_x: + * D_x = A * (P + Pxy) + B * (Q + Qxy) + * where + * A = 2^(x - y) * (2^(x - y) + 1)^-1 + * B = 2^(ndevs - 1 - x) * (2^(x - y) + 1)^-1 + * + * With D_x in hand, we can easily solve for D_y: + * D_y = P + Pxy + D_x + */ + + a = vdev_raidz_pow2[255 + x - y]; + b = vdev_raidz_pow2[255 - (rm->rm_cols - 1 - x)]; + tmp = 255 - vdev_raidz_log2[a ^ 1]; + + aexp = vdev_raidz_log2[vdev_raidz_exp2(a, tmp)]; + bexp = vdev_raidz_log2[vdev_raidz_exp2(b, tmp)]; + + for (i = 0; i < xsize; i++, p++, q++, pxy++, qxy++, xd++, yd++) { + *xd = vdev_raidz_exp2(*p ^ *pxy, aexp) ^ + vdev_raidz_exp2(*q ^ *qxy, bexp); + + if (i < ysize) + *yd = *p ^ *pxy ^ *xd; + } + + zio_buf_free(rm->rm_col[VDEV_RAIDZ_P].rc_data, + rm->rm_col[VDEV_RAIDZ_P].rc_size); + zio_buf_free(rm->rm_col[VDEV_RAIDZ_Q].rc_data, + rm->rm_col[VDEV_RAIDZ_Q].rc_size); + + /* + * Restore the saved parity data. + */ + rm->rm_col[VDEV_RAIDZ_P].rc_data = pdata; + rm->rm_col[VDEV_RAIDZ_Q].rc_data = qdata; +} + + +static int +vdev_raidz_open(vdev_t *vd, uint64_t *asize, uint64_t *ashift) +{ + vdev_t *cvd; + uint64_t nparity = vd->vdev_nparity; + int c, error; + int lasterror = 0; + int numerrors = 0; + + ASSERT(nparity > 0); + + if (nparity > VDEV_RAIDZ_MAXPARITY || + vd->vdev_children < nparity + 1) { + vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL; + return (EINVAL); + } + + for (c = 0; c < vd->vdev_children; c++) { + cvd = vd->vdev_child[c]; + + if ((error = vdev_open(cvd)) != 0) { + lasterror = error; + numerrors++; + continue; + } + + *asize = MIN(*asize - 1, cvd->vdev_asize - 1) + 1; + *ashift = MAX(*ashift, cvd->vdev_ashift); + } + + *asize *= vd->vdev_children; + + if (numerrors > nparity) { + vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS; + return (lasterror); + } + + return (0); +} + +static void +vdev_raidz_close(vdev_t *vd) +{ + int c; + + for (c = 0; c < vd->vdev_children; c++) + vdev_close(vd->vdev_child[c]); +} + +static uint64_t +vdev_raidz_asize(vdev_t *vd, uint64_t psize) +{ + uint64_t asize; + uint64_t ashift = vd->vdev_top->vdev_ashift; + uint64_t cols = vd->vdev_children; + uint64_t nparity = vd->vdev_nparity; + + asize = ((psize - 1) >> ashift) + 1; + asize += nparity * ((asize + cols - nparity - 1) / (cols - nparity)); + asize = roundup(asize, nparity + 1) << ashift; + + return (asize); +} + +static void +vdev_raidz_child_done(zio_t *zio) +{ + raidz_col_t *rc = zio->io_private; + + rc->rc_error = zio->io_error; + rc->rc_tried = 1; + rc->rc_skipped = 0; +} + +static void +vdev_raidz_repair_done(zio_t *zio) +{ + ASSERT(zio->io_private == zio->io_parent); + vdev_raidz_map_free(zio->io_private); +} + +static void +vdev_raidz_io_start(zio_t *zio) +{ + vdev_t *vd = zio->io_vd; + vdev_t *tvd = vd->vdev_top; + vdev_t *cvd; + blkptr_t *bp = zio->io_bp; + raidz_map_t *rm; + raidz_col_t *rc; + int c; + + rm = vdev_raidz_map_alloc(zio, tvd->vdev_ashift, vd->vdev_children, + vd->vdev_nparity); + + ASSERT3U(rm->rm_asize, ==, vdev_psize_to_asize(vd, zio->io_size)); + + if (zio->io_type == ZIO_TYPE_WRITE) { + /* + * Generate RAID parity in the first virtual columns. + */ + if (rm->rm_firstdatacol == 1) + vdev_raidz_generate_parity_p(rm); + else + vdev_raidz_generate_parity_pq(rm); + + for (c = 0; c < rm->rm_cols; c++) { + rc = &rm->rm_col[c]; + cvd = vd->vdev_child[rc->rc_devidx]; + zio_nowait(zio_vdev_child_io(zio, NULL, cvd, + rc->rc_offset, rc->rc_data, rc->rc_size, + zio->io_type, zio->io_priority, ZIO_FLAG_CANFAIL, + vdev_raidz_child_done, rc)); + } + zio_wait_children_done(zio); + return; + } + + ASSERT(zio->io_type == ZIO_TYPE_READ); + + /* + * Iterate over the columns in reverse order so that we hit the parity + * last -- any errors along the way will force us to read the parity + * data. + */ + for (c = rm->rm_cols - 1; c >= 0; c--) { + rc = &rm->rm_col[c]; + cvd = vd->vdev_child[rc->rc_devidx]; + if (vdev_is_dead(cvd)) { + if (c >= rm->rm_firstdatacol) + rm->rm_missingdata++; + else + rm->rm_missingparity++; + rc->rc_error = ENXIO; + rc->rc_tried = 1; /* don't even try */ + rc->rc_skipped = 1; + continue; + } + if (vdev_dtl_contains(&cvd->vdev_dtl_map, bp->blk_birth, 1)) { + if (c >= rm->rm_firstdatacol) + rm->rm_missingdata++; + else + rm->rm_missingparity++; + rc->rc_error = ESTALE; + rc->rc_skipped = 1; + continue; + } + if (c >= rm->rm_firstdatacol || rm->rm_missingdata > 0 || + (zio->io_flags & ZIO_FLAG_SCRUB)) { + zio_nowait(zio_vdev_child_io(zio, NULL, cvd, + rc->rc_offset, rc->rc_data, rc->rc_size, + zio->io_type, zio->io_priority, ZIO_FLAG_CANFAIL, + vdev_raidz_child_done, rc)); + } + } + + zio_wait_children_done(zio); +} + +/* + * Report a checksum error for a child of a RAID-Z device. + */ +static void +raidz_checksum_error(zio_t *zio, raidz_col_t *rc) +{ + vdev_t *vd = zio->io_vd->vdev_child[rc->rc_devidx]; + dprintf_bp(zio->io_bp, "imputed checksum error on %s: ", + vdev_description(vd)); + + if (!(zio->io_flags & ZIO_FLAG_SPECULATIVE)) { + mutex_enter(&vd->vdev_stat_lock); + vd->vdev_stat.vs_checksum_errors++; + mutex_exit(&vd->vdev_stat_lock); + } + + if (!(zio->io_flags & ZIO_FLAG_SPECULATIVE)) + zfs_ereport_post(FM_EREPORT_ZFS_CHECKSUM, + zio->io_spa, vd, zio, rc->rc_offset, rc->rc_size); +} + +/* + * Generate the parity from the data columns. If we tried and were able to + * read the parity without error, verify that the generated parity matches the + * data we read. If it doesn't, we fire off a checksum error. Return the + * number such failures. + */ +static int +raidz_parity_verify(zio_t *zio, raidz_map_t *rm) +{ + void *orig[VDEV_RAIDZ_MAXPARITY]; + int c, ret = 0; + raidz_col_t *rc; + + for (c = 0; c < rm->rm_firstdatacol; c++) { + rc = &rm->rm_col[c]; + if (!rc->rc_tried || rc->rc_error != 0) + continue; + orig[c] = zio_buf_alloc(rc->rc_size); + bcopy(rc->rc_data, orig[c], rc->rc_size); + } + + if (rm->rm_firstdatacol == 1) + vdev_raidz_generate_parity_p(rm); + else + vdev_raidz_generate_parity_pq(rm); + + for (c = 0; c < rm->rm_firstdatacol; c++) { + rc = &rm->rm_col[c]; + if (!rc->rc_tried || rc->rc_error != 0) + continue; + if (bcmp(orig[c], rc->rc_data, rc->rc_size) != 0) { + raidz_checksum_error(zio, rc); + rc->rc_error = ECKSUM; + ret++; + } + zio_buf_free(orig[c], rc->rc_size); + } + + return (ret); +} + +static uint64_t raidz_corrected_p; +static uint64_t raidz_corrected_q; +static uint64_t raidz_corrected_pq; + +static void +vdev_raidz_io_done(zio_t *zio) +{ + vdev_t *vd = zio->io_vd; + vdev_t *cvd; + raidz_map_t *rm = zio->io_vsd; + raidz_col_t *rc, *rc1; + int unexpected_errors = 0; + int parity_errors = 0; + int parity_untried = 0; + int data_errors = 0; + int n, c, c1; + + ASSERT(zio->io_bp != NULL); /* XXX need to add code to enforce this */ + + zio->io_error = 0; + zio->io_numerrors = 0; + + ASSERT(rm->rm_missingparity <= rm->rm_firstdatacol); + ASSERT(rm->rm_missingdata <= rm->rm_cols - rm->rm_firstdatacol); + + for (c = 0; c < rm->rm_cols; c++) { + rc = &rm->rm_col[c]; + + /* + * We preserve any EIOs because those may be worth retrying; + * whereas ECKSUM and ENXIO are more likely to be persistent. + */ + if (rc->rc_error) { + if (zio->io_error != EIO) + zio->io_error = rc->rc_error; + + if (c < rm->rm_firstdatacol) + parity_errors++; + else + data_errors++; + + if (!rc->rc_skipped) + unexpected_errors++; + + zio->io_numerrors++; + } else if (c < rm->rm_firstdatacol && !rc->rc_tried) { + parity_untried++; + } + } + + if (zio->io_type == ZIO_TYPE_WRITE) { + /* + * If this is not a failfast write, and we were able to + * write enough columns to reconstruct the data, good enough. + */ + /* XXPOLICY */ + if (zio->io_numerrors <= rm->rm_firstdatacol && + !(zio->io_flags & ZIO_FLAG_FAILFAST)) + zio->io_error = 0; + + vdev_raidz_map_free(zio); + zio_next_stage(zio); + return; + } + + ASSERT(zio->io_type == ZIO_TYPE_READ); + /* + * There are three potential phases for a read: + * 1. produce valid data from the columns read + * 2. read all disks and try again + * 3. perform combinatorial reconstruction + * + * Each phase is progressively both more expensive and less likely to + * occur. If we encounter more errors than we can repair or all phases + * fail, we have no choice but to return an error. + */ + + /* + * If the number of errors we saw was correctable -- less than or equal + * to the number of parity disks read -- attempt to produce data that + * has a valid checksum. Naturally, this case applies in the absence of + * any errors. + */ + if (zio->io_numerrors <= rm->rm_firstdatacol - parity_untried) { + switch (data_errors) { + case 0: + if (zio_checksum_error(zio) == 0) { + zio->io_error = 0; + + /* + * If we read parity information (unnecessarily + * as it happens since no reconstruction was + * needed) regenerate and verify the parity. + * We also regenerate parity when resilvering + * so we can write it out to the failed device + * later. + */ + if (parity_errors + parity_untried < + rm->rm_firstdatacol || + (zio->io_flags & ZIO_FLAG_RESILVER)) { + n = raidz_parity_verify(zio, rm); + unexpected_errors += n; + ASSERT(parity_errors + n <= + rm->rm_firstdatacol); + } + goto done; + } + break; + + case 1: + /* + * We either attempt to read all the parity columns or + * none of them. If we didn't try to read parity, we + * wouldn't be here in the correctable case. There must + * also have been fewer parity errors than parity + * columns or, again, we wouldn't be in this code path. + */ + ASSERT(parity_untried == 0); + ASSERT(parity_errors < rm->rm_firstdatacol); + + /* + * Find the column that reported the error. + */ + for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { + rc = &rm->rm_col[c]; + if (rc->rc_error != 0) + break; + } + ASSERT(c != rm->rm_cols); + ASSERT(!rc->rc_skipped || rc->rc_error == ENXIO || + rc->rc_error == ESTALE); + + if (rm->rm_col[VDEV_RAIDZ_P].rc_error == 0) { + vdev_raidz_reconstruct_p(rm, c); + } else { + ASSERT(rm->rm_firstdatacol > 1); + vdev_raidz_reconstruct_q(rm, c); + } + + if (zio_checksum_error(zio) == 0) { + zio->io_error = 0; + if (rm->rm_col[VDEV_RAIDZ_P].rc_error == 0) + atomic_inc_64(&raidz_corrected_p); + else + atomic_inc_64(&raidz_corrected_q); + + /* + * If there's more than one parity disk that + * was successfully read, confirm that the + * other parity disk produced the correct data. + * This routine is suboptimal in that it + * regenerates both the parity we wish to test + * as well as the parity we just used to + * perform the reconstruction, but this should + * be a relatively uncommon case, and can be + * optimized if it becomes a problem. + * We also regenerate parity when resilvering + * so we can write it out to the failed device + * later. + */ + if (parity_errors < rm->rm_firstdatacol - 1 || + (zio->io_flags & ZIO_FLAG_RESILVER)) { + n = raidz_parity_verify(zio, rm); + unexpected_errors += n; + ASSERT(parity_errors + n <= + rm->rm_firstdatacol); + } + + goto done; + } + break; + + case 2: + /* + * Two data column errors require double parity. + */ + ASSERT(rm->rm_firstdatacol == 2); + + /* + * Find the two columns that reported errors. + */ + for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { + rc = &rm->rm_col[c]; + if (rc->rc_error != 0) + break; + } + ASSERT(c != rm->rm_cols); + ASSERT(!rc->rc_skipped || rc->rc_error == ENXIO || + rc->rc_error == ESTALE); + + for (c1 = c++; c < rm->rm_cols; c++) { + rc = &rm->rm_col[c]; + if (rc->rc_error != 0) + break; + } + ASSERT(c != rm->rm_cols); + ASSERT(!rc->rc_skipped || rc->rc_error == ENXIO || + rc->rc_error == ESTALE); + + vdev_raidz_reconstruct_pq(rm, c1, c); + + if (zio_checksum_error(zio) == 0) { + zio->io_error = 0; + atomic_inc_64(&raidz_corrected_pq); + + goto done; + } + break; + + default: + ASSERT(rm->rm_firstdatacol <= 2); + ASSERT(0); + } + } + + /* + * This isn't a typical situation -- either we got a read error or + * a child silently returned bad data. Read every block so we can + * try again with as much data and parity as we can track down. If + * we've already been through once before, all children will be marked + * as tried so we'll proceed to combinatorial reconstruction. + */ + unexpected_errors = 1; + rm->rm_missingdata = 0; + rm->rm_missingparity = 0; + + for (c = 0; c < rm->rm_cols; c++) { + if (rm->rm_col[c].rc_tried) + continue; + + zio->io_error = 0; + zio_vdev_io_redone(zio); + do { + rc = &rm->rm_col[c]; + if (rc->rc_tried) + continue; + zio_nowait(zio_vdev_child_io(zio, NULL, + vd->vdev_child[rc->rc_devidx], + rc->rc_offset, rc->rc_data, rc->rc_size, + zio->io_type, zio->io_priority, ZIO_FLAG_CANFAIL, + vdev_raidz_child_done, rc)); + } while (++c < rm->rm_cols); + dprintf("rereading\n"); + zio_wait_children_done(zio); + return; + } + + /* + * At this point we've attempted to reconstruct the data given the + * errors we detected, and we've attempted to read all columns. There + * must, therefore, be one or more additional problems -- silent errors + * resulting in invalid data rather than explicit I/O errors resulting + * in absent data. Before we attempt combinatorial reconstruction make + * sure we have a chance of coming up with the right answer. + */ + if (zio->io_numerrors >= rm->rm_firstdatacol) { + ASSERT(zio->io_error != 0); + goto done; + } + + if (rm->rm_col[VDEV_RAIDZ_P].rc_error == 0) { + /* + * Attempt to reconstruct the data from parity P. + */ + for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { + void *orig; + rc = &rm->rm_col[c]; + + orig = zio_buf_alloc(rc->rc_size); + bcopy(rc->rc_data, orig, rc->rc_size); + vdev_raidz_reconstruct_p(rm, c); + + if (zio_checksum_error(zio) == 0) { + zio_buf_free(orig, rc->rc_size); + zio->io_error = 0; + atomic_inc_64(&raidz_corrected_p); + + /* + * If this child didn't know that it returned + * bad data, inform it. + */ + if (rc->rc_tried && rc->rc_error == 0) + raidz_checksum_error(zio, rc); + rc->rc_error = ECKSUM; + goto done; + } + + bcopy(orig, rc->rc_data, rc->rc_size); + zio_buf_free(orig, rc->rc_size); + } + } + + if (rm->rm_firstdatacol > 1 && rm->rm_col[VDEV_RAIDZ_Q].rc_error == 0) { + /* + * Attempt to reconstruct the data from parity Q. + */ + for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { + void *orig; + rc = &rm->rm_col[c]; + + orig = zio_buf_alloc(rc->rc_size); + bcopy(rc->rc_data, orig, rc->rc_size); + vdev_raidz_reconstruct_q(rm, c); + + if (zio_checksum_error(zio) == 0) { + zio_buf_free(orig, rc->rc_size); + zio->io_error = 0; + atomic_inc_64(&raidz_corrected_q); + + /* + * If this child didn't know that it returned + * bad data, inform it. + */ + if (rc->rc_tried && rc->rc_error == 0) + raidz_checksum_error(zio, rc); + rc->rc_error = ECKSUM; + goto done; + } + + bcopy(orig, rc->rc_data, rc->rc_size); + zio_buf_free(orig, rc->rc_size); + } + } + + if (rm->rm_firstdatacol > 1 && + rm->rm_col[VDEV_RAIDZ_P].rc_error == 0 && + rm->rm_col[VDEV_RAIDZ_Q].rc_error == 0) { + /* + * Attempt to reconstruct the data from both P and Q. + */ + for (c = rm->rm_firstdatacol; c < rm->rm_cols - 1; c++) { + void *orig, *orig1; + rc = &rm->rm_col[c]; + + orig = zio_buf_alloc(rc->rc_size); + bcopy(rc->rc_data, orig, rc->rc_size); + + for (c1 = c + 1; c1 < rm->rm_cols; c1++) { + rc1 = &rm->rm_col[c1]; + + orig1 = zio_buf_alloc(rc1->rc_size); + bcopy(rc1->rc_data, orig1, rc1->rc_size); + + vdev_raidz_reconstruct_pq(rm, c, c1); + + if (zio_checksum_error(zio) == 0) { + zio_buf_free(orig, rc->rc_size); + zio_buf_free(orig1, rc1->rc_size); + zio->io_error = 0; + atomic_inc_64(&raidz_corrected_pq); + + /* + * If these children didn't know they + * returned bad data, inform them. + */ + if (rc->rc_tried && rc->rc_error == 0) + raidz_checksum_error(zio, rc); + if (rc1->rc_tried && rc1->rc_error == 0) + raidz_checksum_error(zio, rc1); + + rc->rc_error = ECKSUM; + rc1->rc_error = ECKSUM; + + goto done; + } + + bcopy(orig1, rc1->rc_data, rc1->rc_size); + zio_buf_free(orig1, rc1->rc_size); + } + + bcopy(orig, rc->rc_data, rc->rc_size); + zio_buf_free(orig, rc->rc_size); + } + } + + /* + * All combinations failed to checksum. Generate checksum ereports for + * all children. + */ + zio->io_error = ECKSUM; + if (!(zio->io_flags & ZIO_FLAG_SPECULATIVE)) { + for (c = 0; c < rm->rm_cols; c++) { + rc = &rm->rm_col[c]; + zfs_ereport_post(FM_EREPORT_ZFS_CHECKSUM, + zio->io_spa, vd->vdev_child[rc->rc_devidx], zio, + rc->rc_offset, rc->rc_size); + } + } + +done: + zio_checksum_verified(zio); + + if (zio->io_error == 0 && (spa_mode & FWRITE) && + (unexpected_errors || (zio->io_flags & ZIO_FLAG_RESILVER))) { + zio_t *rio; + + /* + * Use the good data we have in hand to repair damaged children. + * + * We issue all repair I/Os as children of 'rio' to arrange + * that vdev_raidz_map_free(zio) will be invoked after all + * repairs complete, but before we advance to the next stage. + */ + rio = zio_null(zio, zio->io_spa, + vdev_raidz_repair_done, zio, ZIO_FLAG_CANFAIL); + + for (c = 0; c < rm->rm_cols; c++) { + rc = &rm->rm_col[c]; + cvd = vd->vdev_child[rc->rc_devidx]; + + if (rc->rc_error == 0) + continue; + + dprintf("%s resilvered %s @ 0x%llx error %d\n", + vdev_description(vd), + vdev_description(cvd), + zio->io_offset, rc->rc_error); + + zio_nowait(zio_vdev_child_io(rio, NULL, cvd, + rc->rc_offset, rc->rc_data, rc->rc_size, + ZIO_TYPE_WRITE, zio->io_priority, + ZIO_FLAG_IO_REPAIR | ZIO_FLAG_DONT_PROPAGATE | + ZIO_FLAG_CANFAIL, NULL, NULL)); + } + + zio_nowait(rio); + zio_wait_children_done(zio); + return; + } + + vdev_raidz_map_free(zio); + zio_next_stage(zio); +} + +static void +vdev_raidz_state_change(vdev_t *vd, int faulted, int degraded) +{ + if (faulted > vd->vdev_nparity) + vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN, + VDEV_AUX_NO_REPLICAS); + else if (degraded + faulted != 0) + vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE); + else + vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE); +} + +vdev_ops_t vdev_raidz_ops = { + vdev_raidz_open, + vdev_raidz_close, + vdev_raidz_asize, + vdev_raidz_io_start, + vdev_raidz_io_done, + vdev_raidz_state_change, + VDEV_TYPE_RAIDZ, /* name of this vdev type */ + B_FALSE /* not a leaf vdev */ +}; |
