/* * 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. */ #include __FBSDID("$FreeBSD$"); static uint64_t zfs_crc64_table[256]; static void zfs_init_crc(void) { int i, j; uint64_t *ct; /* * Calculate the crc64 table (used for the zap hash * function). */ if (zfs_crc64_table[128] != ZFS_CRC64_POLY) { memset(zfs_crc64_table, 0, sizeof(zfs_crc64_table)); for (i = 0; i < 256; i++) for (ct = zfs_crc64_table + i, *ct = i, j = 8; j > 0; j--) *ct = (*ct >> 1) ^ (-(*ct & 1) & ZFS_CRC64_POLY); } } static void zio_checksum_off(const void *buf, uint64_t size, zio_cksum_t *zcp) { ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0); } /* * Signature for checksum functions. */ typedef void zio_checksum_t(const void *data, uint64_t size, zio_cksum_t *zcp); /* * Information about each checksum function. */ typedef struct zio_checksum_info { zio_checksum_t *ci_func[2]; /* checksum function for each byteorder */ int ci_correctable; /* number of correctable bits */ int ci_zbt; /* uses zio block tail? */ const char *ci_name; /* descriptive name */ } zio_checksum_info_t; #include "fletcher.c" #include "sha256.c" static zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = { {{NULL, NULL}, 0, 0, "inherit"}, {{NULL, NULL}, 0, 0, "on"}, {{zio_checksum_off, zio_checksum_off}, 0, 0, "off"}, {{zio_checksum_SHA256, NULL}, 1, 1, "label"}, {{zio_checksum_SHA256, NULL}, 1, 1, "gang_header"}, {{fletcher_2_native, NULL}, 0, 1, "zilog"}, {{fletcher_2_native, NULL}, 0, 0, "fletcher2"}, {{fletcher_4_native, NULL}, 1, 0, "fletcher4"}, {{zio_checksum_SHA256, NULL}, 1, 0, "SHA256"}, }; /* * Common signature for all zio compress/decompress functions. */ typedef size_t zio_compress_func_t(void *src, void *dst, size_t s_len, size_t d_len, int); typedef int zio_decompress_func_t(void *src, void *dst, size_t s_len, size_t d_len, int); /* * Information about each compression function. */ typedef struct zio_compress_info { zio_compress_func_t *ci_compress; /* compression function */ zio_decompress_func_t *ci_decompress; /* decompression function */ int ci_level; /* level parameter */ const char *ci_name; /* algorithm name */ } zio_compress_info_t; #include "lzjb.c" /* * Compression vectors. */ static zio_compress_info_t zio_compress_table[ZIO_COMPRESS_FUNCTIONS] = { {NULL, NULL, 0, "inherit"}, {NULL, NULL, 0, "on"}, {NULL, NULL, 0, "uncompressed"}, {NULL, lzjb_decompress, 0, "lzjb"}, {NULL, NULL, 0, "empty"}, {NULL, NULL, 1, "gzip-1"}, {NULL, NULL, 2, "gzip-2"}, {NULL, NULL, 3, "gzip-3"}, {NULL, NULL, 4, "gzip-4"}, {NULL, NULL, 5, "gzip-5"}, {NULL, NULL, 6, "gzip-6"}, {NULL, NULL, 7, "gzip-7"}, {NULL, NULL, 8, "gzip-8"}, {NULL, NULL, 9, "gzip-9"}, }; static int zio_checksum_error(const blkptr_t *bp, void *data) { zio_cksum_t zc = bp->blk_cksum; unsigned int checksum = BP_GET_CHECKSUM(bp); uint64_t size = BP_GET_PSIZE(bp); zio_block_tail_t *zbt = (zio_block_tail_t *)((char *)data + size) - 1; zio_checksum_info_t *ci = &zio_checksum_table[checksum]; zio_cksum_t actual_cksum, expected_cksum; if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL) return (EINVAL); if (ci->ci_zbt) { expected_cksum = zbt->zbt_cksum; zbt->zbt_cksum = zc; ci->ci_func[0](data, size, &actual_cksum); zbt->zbt_cksum = expected_cksum; zc = expected_cksum; } else { /* ASSERT(!BP_IS_GANG(bp)); */ ci->ci_func[0](data, size, &actual_cksum); } if (!ZIO_CHECKSUM_EQUAL(actual_cksum, zc)) { /*printf("ZFS: read checksum failed\n");*/ return (EIO); } return (0); } static int zio_decompress_data(int cpfunc, void *src, uint64_t srcsize, void *dest, uint64_t destsize) { zio_compress_info_t *ci = &zio_compress_table[cpfunc]; /* ASSERT((uint_t)cpfunc < ZIO_COMPRESS_FUNCTIONS); */ if (!ci->ci_decompress) { printf("ZFS: unsupported compression algorithm %u\n", cpfunc); return (EIO); } return (ci->ci_decompress(src, dest, srcsize, destsize, ci->ci_level)); } static uint64_t zap_hash(uint64_t salt, const char *name) { const uint8_t *cp; uint8_t c; uint64_t crc = salt; /*ASSERT(crc != 0);*/ /*ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY);*/ for (cp = (const uint8_t *)name; (c = *cp) != '\0'; cp++) crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ c) & 0xFF]; /* * Only use 28 bits, since we need 4 bits in the cookie for the * collision differentiator. We MUST use the high bits, since * those are the onces that we first pay attention to when * chosing the bucket. */ crc &= ~((1ULL << (64 - ZAP_HASHBITS)) - 1); return (crc); } static char *zfs_alloc_temp(size_t sz); 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; #define VDEV_RAIDZ_P 0 #define VDEV_RAIDZ_Q 1 static void vdev_raidz_reconstruct_p(raidz_col_t *cols, int nparity, int acols, int x) { uint64_t *dst, *src, xcount, ccount, count, i; int c; xcount = cols[x].rc_size / sizeof (src[0]); //ASSERT(xcount <= cols[VDEV_RAIDZ_P].rc_size / sizeof (src[0])); //ASSERT(xcount > 0); src = cols[VDEV_RAIDZ_P].rc_data; dst = cols[x].rc_data; for (i = 0; i < xcount; i++, dst++, src++) { *dst = *src; } for (c = nparity; c < acols; c++) { src = cols[c].rc_data; dst = cols[x].rc_data; if (c == x) continue; ccount = cols[c].rc_size / sizeof (src[0]); count = MIN(ccount, xcount); for (i = 0; i < count; i++, dst++, src++) { *dst ^= *src; } } } /* * 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(uint8_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 void vdev_raidz_generate_parity_pq(raidz_col_t *cols, int nparity, int acols) { uint64_t *q, *p, *src, pcount, ccount, mask, i; int c; pcount = cols[VDEV_RAIDZ_P].rc_size / sizeof (src[0]); //ASSERT(cols[VDEV_RAIDZ_P].rc_size == cols[VDEV_RAIDZ_Q].rc_size); for (c = nparity; c < acols; c++) { src = cols[c].rc_data; p = cols[VDEV_RAIDZ_P].rc_data; q = cols[VDEV_RAIDZ_Q].rc_data; ccount = cols[c].rc_size / sizeof (src[0]); if (c == nparity) { //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_q(raidz_col_t *cols, int nparity, int acols, int x) { uint64_t *dst, *src, xcount, ccount, count, mask, i; uint8_t *b; int c, j, exp; xcount = cols[x].rc_size / sizeof (src[0]); //ASSERT(xcount <= cols[VDEV_RAIDZ_Q].rc_size / sizeof (src[0])); for (c = nparity; c < acols; c++) { src = cols[c].rc_data; dst = cols[x].rc_data; if (c == x) ccount = 0; else ccount = cols[c].rc_size / sizeof (src[0]); count = MIN(ccount, xcount); if (c == nparity) { 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 = cols[VDEV_RAIDZ_Q].rc_data; dst = cols[x].rc_data; exp = 255 - (acols - 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_col_t *cols, int nparity, int acols, 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 >= nparity); //ASSERT(y < acols); //ASSERT(cols[x].rc_size >= cols[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 = cols[VDEV_RAIDZ_P].rc_data; qdata = cols[VDEV_RAIDZ_Q].rc_data; xsize = cols[x].rc_size; ysize = cols[y].rc_size; cols[VDEV_RAIDZ_P].rc_data = zfs_alloc_temp(cols[VDEV_RAIDZ_P].rc_size); cols[VDEV_RAIDZ_Q].rc_data = zfs_alloc_temp(cols[VDEV_RAIDZ_Q].rc_size); cols[x].rc_size = 0; cols[y].rc_size = 0; vdev_raidz_generate_parity_pq(cols, nparity, acols); cols[x].rc_size = xsize; cols[y].rc_size = ysize; p = pdata; q = qdata; pxy = cols[VDEV_RAIDZ_P].rc_data; qxy = cols[VDEV_RAIDZ_Q].rc_data; xd = cols[x].rc_data; yd = cols[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 - (acols - 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; } /* * Restore the saved parity data. */ cols[VDEV_RAIDZ_P].rc_data = pdata; cols[VDEV_RAIDZ_Q].rc_data = qdata; } static int vdev_raidz_read(vdev_t *vdev, const blkptr_t *bp, void *buf, off_t offset, size_t bytes) { size_t psize = BP_GET_PSIZE(bp); vdev_t *kid; int unit_shift = vdev->v_ashift; int dcols = vdev->v_nchildren; int nparity = vdev->v_nparity; int missingdata, missingparity; int parity_errors, data_errors, unexpected_errors, total_errors; int parity_untried; uint64_t b = offset >> unit_shift; uint64_t s = psize >> unit_shift; uint64_t f = b % dcols; uint64_t o = (b / dcols) << unit_shift; int q, r, c, c1, bc, col, acols, coff, devidx, asize, n; static raidz_col_t cols[16]; raidz_col_t *rc, *rc1; q = s / (dcols - nparity); r = s - q * (dcols - nparity); bc = (r == 0 ? 0 : r + nparity); acols = (q == 0 ? bc : dcols); asize = 0; for (c = 0; c < acols; c++) { col = f + c; coff = o; if (col >= dcols) { col -= dcols; coff += 1ULL << unit_shift; } cols[c].rc_devidx = col; cols[c].rc_offset = coff; cols[c].rc_size = (q + (c < bc)) << unit_shift; cols[c].rc_data = NULL; cols[c].rc_error = 0; cols[c].rc_tried = 0; cols[c].rc_skipped = 0; asize += cols[c].rc_size; } asize = roundup(asize, (nparity + 1) << unit_shift); for (c = 0; c < nparity; c++) { cols[c].rc_data = zfs_alloc_temp(cols[c].rc_size); } cols[c].rc_data = buf; for (c = c + 1; c < acols; c++) cols[c].rc_data = (char *)cols[c - 1].rc_data + cols[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(acols >= 2); //ASSERT(cols[0].rc_size == cols[1].rc_size); if (nparity == 1 && (offset & (1ULL << 20))) { devidx = cols[0].rc_devidx; o = cols[0].rc_offset; cols[0].rc_devidx = cols[1].rc_devidx; cols[0].rc_offset = cols[1].rc_offset; cols[1].rc_devidx = devidx; cols[1].rc_offset = o; } /* * 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. */ missingdata = 0; missingparity = 0; for (c = acols - 1; c >= 0; c--) { rc = &cols[c]; devidx = rc->rc_devidx; STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) if (kid->v_id == devidx) break; if (kid == NULL || kid->v_state != VDEV_STATE_HEALTHY) { if (c >= nparity) missingdata++; else missingparity++; rc->rc_error = ENXIO; rc->rc_tried = 1; /* don't even try */ rc->rc_skipped = 1; continue; } #if 0 /* * Too hard for the bootcode */ if (vdev_dtl_contains(&cvd->vdev_dtl_map, bp->blk_birth, 1)) { if (c >= nparity) rm->rm_missingdata++; else rm->rm_missingparity++; rc->rc_error = ESTALE; rc->rc_skipped = 1; continue; } #endif if (c >= nparity || missingdata > 0) { if (rc->rc_data) rc->rc_error = kid->v_read(kid, NULL, rc->rc_data, rc->rc_offset, rc->rc_size); else rc->rc_error = ENXIO; rc->rc_tried = 1; rc->rc_skipped = 0; } } reconstruct: parity_errors = 0; data_errors = 0; unexpected_errors = 0; total_errors = 0; parity_untried = 0; for (c = 0; c < acols; c++) { rc = &cols[c]; if (rc->rc_error) { if (c < nparity) parity_errors++; else data_errors++; if (!rc->rc_skipped) unexpected_errors++; total_errors++; } else if (c < nparity && !rc->rc_tried) { parity_untried++; } } /* * 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 (total_errors <= nparity - parity_untried) { switch (data_errors) { case 0: if (zio_checksum_error(bp, buf) == 0) return (0); 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 < nparity); /* * Find the column that reported the error. */ for (c = nparity; c < acols; c++) { rc = &cols[c]; if (rc->rc_error != 0) break; } //ASSERT(c != acols); //ASSERT(!rc->rc_skipped || rc->rc_error == ENXIO || rc->rc_error == ESTALE); if (cols[VDEV_RAIDZ_P].rc_error == 0) { vdev_raidz_reconstruct_p(cols, nparity, acols, c); } else { //ASSERT(nparity > 1); vdev_raidz_reconstruct_q(cols, nparity, acols, c); } if (zio_checksum_error(bp, buf) == 0) return (0); break; case 2: /* * Two data column errors require double parity. */ //ASSERT(nparity == 2); /* * Find the two columns that reported errors. */ for (c = nparity; c < acols; c++) { rc = &cols[c]; if (rc->rc_error != 0) break; } //ASSERT(c != acols); //ASSERT(!rc->rc_skipped || rc->rc_error == ENXIO || rc->rc_error == ESTALE); for (c1 = c++; c < acols; c++) { rc = &cols[c]; if (rc->rc_error != 0) break; } //ASSERT(c != acols); //ASSERT(!rc->rc_skipped || rc->rc_error == ENXIO || rc->rc_error == ESTALE); vdev_raidz_reconstruct_pq(cols, nparity, acols, c1, c); if (zio_checksum_error(bp, buf) == 0) return (0); break; default: break; //ASSERT(nparity <= 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. */ n = 0; for (c = 0; c < acols; c++) { rc = &cols[c]; if (rc->rc_tried) continue; devidx = rc->rc_devidx; STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) if (kid->v_id == devidx) break; if (kid == NULL || kid->v_state != VDEV_STATE_HEALTHY) { rc->rc_error = ENXIO; rc->rc_tried = 1; /* don't even try */ rc->rc_skipped = 1; continue; } if (rc->rc_data) rc->rc_error = kid->v_read(kid, NULL, rc->rc_data, rc->rc_offset, rc->rc_size); else rc->rc_error = ENXIO; if (rc->rc_error == 0) n++; rc->rc_tried = 1; rc->rc_skipped = 0; } /* * If we managed to read anything more, retry the * reconstruction. */ if (n) goto reconstruct; /* * 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 (total_errors >= nparity) { return (EIO); } asize = 0; for (c = 0; c < acols; c++) { rc = &cols[c]; if (rc->rc_size > asize) asize = rc->rc_size; } if (cols[VDEV_RAIDZ_P].rc_error == 0) { /* * Attempt to reconstruct the data from parity P. */ void *orig; orig = zfs_alloc_temp(asize); for (c = nparity; c < acols; c++) { rc = &cols[c]; memcpy(orig, rc->rc_data, rc->rc_size); vdev_raidz_reconstruct_p(cols, nparity, acols, c); if (zio_checksum_error(bp, buf) == 0) return (0); memcpy(rc->rc_data, orig, rc->rc_size); } } if (nparity > 1 && cols[VDEV_RAIDZ_Q].rc_error == 0) { /* * Attempt to reconstruct the data from parity Q. */ void *orig; orig = zfs_alloc_temp(asize); for (c = nparity; c < acols; c++) { rc = &cols[c]; memcpy(orig, rc->rc_data, rc->rc_size); vdev_raidz_reconstruct_q(cols, nparity, acols, c); if (zio_checksum_error(bp, buf) == 0) return (0); memcpy(rc->rc_data, orig, rc->rc_size); } } if (nparity > 1 && cols[VDEV_RAIDZ_P].rc_error == 0 && cols[VDEV_RAIDZ_Q].rc_error == 0) { /* * Attempt to reconstruct the data from both P and Q. */ void *orig, *orig1; orig = zfs_alloc_temp(asize); orig1 = zfs_alloc_temp(asize); for (c = nparity; c < acols - 1; c++) { rc = &cols[c]; memcpy(orig, rc->rc_data, rc->rc_size); for (c1 = c + 1; c1 < acols; c1++) { rc1 = &cols[c1]; memcpy(orig1, rc1->rc_data, rc1->rc_size); vdev_raidz_reconstruct_pq(cols, nparity, acols, c, c1); if (zio_checksum_error(bp, buf) == 0) return (0); memcpy(rc1->rc_data, orig1, rc1->rc_size); } memcpy(rc->rc_data, orig, rc->rc_size); } } return (EIO); }