/* * 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 2008 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ #include #include #include #include #include #include #include /* * 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 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])); } 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; zio->io_vsd_free = vdev_raidz_map_free; return (rm); } 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 int 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, 0, vdev_raidz_child_done, rc)); } return (ZIO_PIPELINE_CONTINUE); } 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_readable(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, 0, vdev_raidz_child_done, rc)); } } return (ZIO_PIPELINE_CONTINUE); } /* * 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]; 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 int vdev_raidz_worst_error(raidz_map_t *rm) { int error = 0; for (int c = 0; c < rm->rm_cols; c++) error = zio_worst_error(error, rm->rm_col[c].rc_error); return (error); } 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 = NULL, *rc1; int unexpected_errors = 0; int parity_errors = 0; int parity_untried = 0; int data_errors = 0; int total_errors = 0; int n, c, c1; ASSERT(zio->io_bp != NULL); /* XXX need to add code to enforce this */ 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]; if (rc->rc_error) { ASSERT(rc->rc_error != ECKSUM); /* child has no bp */ if (c < rm->rm_firstdatacol) parity_errors++; else data_errors++; if (!rc->rc_skipped) unexpected_errors++; total_errors++; } else if (c < rm->rm_firstdatacol && !rc->rc_tried) { parity_untried++; } } if (zio->io_type == ZIO_TYPE_WRITE) { /* * XXX -- for now, treat partial writes as a success. * (If we couldn't write enough columns to reconstruct * the data, the I/O failed. Otherwise, good enough.) * * Now that we support write reallocation, it would be better * to treat partial failure as real failure unless there are * no non-degraded top-level vdevs left, and not update DTLs * if we intend to reallocate. */ /* XXPOLICY */ if (total_errors > rm->rm_firstdatacol) zio->io_error = vdev_raidz_worst_error(rm); 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 (total_errors <= rm->rm_firstdatacol - parity_untried) { switch (data_errors) { case 0: if (zio_checksum_error(zio) == 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) { 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) { 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_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, 0, vdev_raidz_child_done, rc)); } while (++c < rm->rm_cols); 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 (total_errors >= rm->rm_firstdatacol) { zio->io_error = vdev_raidz_worst_error(rm); /* * If there were exactly as many device errors as parity * columns, yet we couldn't reconstruct the data, then at * least one device must have returned bad data silently. */ if (total_errors == rm->rm_firstdatacol) zio->io_error = zio_worst_error(zio->io_error, ECKSUM); 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); 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); 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); 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))) { /* * Use the good data we have in hand to repair damaged children. */ 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; zio_nowait(zio_vdev_child_io(zio, NULL, cvd, rc->rc_offset, rc->rc_data, rc->rc_size, ZIO_TYPE_WRITE, zio->io_priority, ZIO_FLAG_IO_REPAIR, NULL, NULL)); } } } 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 */ };