/* * 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 https://opensource.org/licenses/CDDL-1.0. * 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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2012, 2020 by Delphix. All rights reserved. * Copyright (c) 2016 Gvozden Nešković. All rights reserved. */ #include #include #include #include #include #include #include #include #include #include #include #ifdef ZFS_DEBUG #include /* For vdev_xlate() in vdev_raidz_io_verify() */ #endif /* * Virtual device vector for RAID-Z. * * This vdev supports single, double, and triple parity. For single parity, * we use a simple XOR of all the data columns. For double or triple parity, * we use a special case of Reed-Solomon coding. This extends the * technique described in "The mathematics of RAID-6" by H. Peter Anvin by * drawing on the system described in "A Tutorial on Reed-Solomon Coding for * Fault-Tolerance in RAID-like Systems" by James S. Plank on which the * former is also based. The latter is designed to provide higher performance * for writes. * * Note that the Plank paper claimed to support arbitrary N+M, but was then * amended six years later identifying a critical flaw that invalidates its * claims. Nevertheless, the technique can be adapted to work for up to * triple parity. For additional parity, the amendment "Note: Correction to * the 1997 Tutorial on Reed-Solomon Coding" by James S. Plank and Ying Ding * is viable, but the additional complexity means that write performance will * suffer. * * All of the methods above operate on a Galois field, defined over the * integers mod 2^N. In our case we choose N=8 for GF(8) so that all elements * can be expressed with 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)). * As an aside, this multiplication is derived from the error correcting * primitive polynomial x^8 + x^4 + x^3 + x^2 + 1. * * 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 therefore * A ^ (255 - 1) = A^254. * * The up-to-three parity columns, P, Q, R 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 * R = 4^n-1 * D_0 + 4^n-2 * D_1 + ... + 4^1 * D_n-2 + 4^0 * D_n-1 * = ((...((D_0) * 4 + D_1) * 4 + ...) * 4 + D_n-2) * 4 + D_n-1 * * We chose 1, 2, and 4 as our generators because 1 corresponds to the trivial * XOR operation, and 2 and 4 can be computed quickly and generate linearly- * independent coefficients. (There are no additional coefficients that have * this property which is why the uncorrected Plank method breaks down.) * * See the reconstruction code below for how P, Q and R can used individually * or in concert to recover missing data columns. */ #define VDEV_RAIDZ_P 0 #define VDEV_RAIDZ_Q 1 #define VDEV_RAIDZ_R 2 #define VDEV_RAIDZ_MUL_2(x) (((x) << 1) ^ (((x) & 0x80) ? 0x1d : 0)) #define VDEV_RAIDZ_MUL_4(x) (VDEV_RAIDZ_MUL_2(VDEV_RAIDZ_MUL_2(x))) /* * We provide a mechanism to perform the field multiplication operation on a * 64-bit value all at once rather than a byte at a time. This works by * creating a mask from the top bit in each byte and using that to * conditionally apply the XOR of 0x1d. */ #define VDEV_RAIDZ_64MUL_2(x, mask) \ { \ (mask) = (x) & 0x8080808080808080ULL; \ (mask) = ((mask) << 1) - ((mask) >> 7); \ (x) = (((x) << 1) & 0xfefefefefefefefeULL) ^ \ ((mask) & 0x1d1d1d1d1d1d1d1dULL); \ } #define VDEV_RAIDZ_64MUL_4(x, mask) \ { \ VDEV_RAIDZ_64MUL_2((x), mask); \ VDEV_RAIDZ_64MUL_2((x), mask); \ } static void vdev_raidz_row_free(raidz_row_t *rr) { for (int c = 0; c < rr->rr_cols; c++) { raidz_col_t *rc = &rr->rr_col[c]; if (rc->rc_size != 0) abd_free(rc->rc_abd); if (rc->rc_orig_data != NULL) abd_free(rc->rc_orig_data); } if (rr->rr_abd_empty != NULL) abd_free(rr->rr_abd_empty); kmem_free(rr, offsetof(raidz_row_t, rr_col[rr->rr_scols])); } void vdev_raidz_map_free(raidz_map_t *rm) { for (int i = 0; i < rm->rm_nrows; i++) vdev_raidz_row_free(rm->rm_row[i]); kmem_free(rm, offsetof(raidz_map_t, rm_row[rm->rm_nrows])); } static void vdev_raidz_map_free_vsd(zio_t *zio) { raidz_map_t *rm = zio->io_vsd; vdev_raidz_map_free(rm); } const zio_vsd_ops_t vdev_raidz_vsd_ops = { .vsd_free = vdev_raidz_map_free_vsd, }; static void vdev_raidz_map_alloc_write(zio_t *zio, raidz_map_t *rm, uint64_t ashift) { int c; int nwrapped = 0; uint64_t off = 0; raidz_row_t *rr = rm->rm_row[0]; ASSERT3U(zio->io_type, ==, ZIO_TYPE_WRITE); ASSERT3U(rm->rm_nrows, ==, 1); /* * Pad any parity columns with additional space to account for skip * sectors. */ if (rm->rm_skipstart < rr->rr_firstdatacol) { ASSERT0(rm->rm_skipstart); nwrapped = rm->rm_nskip; } else if (rr->rr_scols < (rm->rm_skipstart + rm->rm_nskip)) { nwrapped = (rm->rm_skipstart + rm->rm_nskip) % rr->rr_scols; } /* * Optional single skip sectors (rc_size == 0) will be handled in * vdev_raidz_io_start_write(). */ int skipped = rr->rr_scols - rr->rr_cols; /* Allocate buffers for the parity columns */ for (c = 0; c < rr->rr_firstdatacol; c++) { raidz_col_t *rc = &rr->rr_col[c]; /* * Parity columns will pad out a linear ABD to account for * the skip sector. A linear ABD is used here because * parity calculations use the ABD buffer directly to calculate * parity. This avoids doing a memcpy back to the ABD after the * parity has been calculated. By issuing the parity column * with the skip sector we can reduce contention on the child * VDEV queue locks (vq_lock). */ if (c < nwrapped) { rc->rc_abd = abd_alloc_linear( rc->rc_size + (1ULL << ashift), B_FALSE); abd_zero_off(rc->rc_abd, rc->rc_size, 1ULL << ashift); skipped++; } else { rc->rc_abd = abd_alloc_linear(rc->rc_size, B_FALSE); } } for (off = 0; c < rr->rr_cols; c++) { raidz_col_t *rc = &rr->rr_col[c]; abd_t *abd = abd_get_offset_struct(&rc->rc_abdstruct, zio->io_abd, off, rc->rc_size); /* * Generate I/O for skip sectors to improve aggregation * continuity. We will use gang ABD's to reduce contention * on the child VDEV queue locks (vq_lock) by issuing * a single I/O that contains the data and skip sector. * * It is important to make sure that rc_size is not updated * even though we are adding a skip sector to the ABD. When * calculating the parity in vdev_raidz_generate_parity_row() * the rc_size is used to iterate through the ABD's. We can * not have zero'd out skip sectors used for calculating * parity for raidz, because those same sectors are not used * during reconstruction. */ if (c >= rm->rm_skipstart && skipped < rm->rm_nskip) { rc->rc_abd = abd_alloc_gang(); abd_gang_add(rc->rc_abd, abd, B_TRUE); abd_gang_add(rc->rc_abd, abd_get_zeros(1ULL << ashift), B_TRUE); skipped++; } else { rc->rc_abd = abd; } off += rc->rc_size; } ASSERT3U(off, ==, zio->io_size); ASSERT3S(skipped, ==, rm->rm_nskip); } static void vdev_raidz_map_alloc_read(zio_t *zio, raidz_map_t *rm) { int c; raidz_row_t *rr = rm->rm_row[0]; ASSERT3U(rm->rm_nrows, ==, 1); /* Allocate buffers for the parity columns */ for (c = 0; c < rr->rr_firstdatacol; c++) rr->rr_col[c].rc_abd = abd_alloc_linear(rr->rr_col[c].rc_size, B_FALSE); for (uint64_t off = 0; c < rr->rr_cols; c++) { raidz_col_t *rc = &rr->rr_col[c]; rc->rc_abd = abd_get_offset_struct(&rc->rc_abdstruct, zio->io_abd, off, rc->rc_size); off += rc->rc_size; } } /* * Divides the IO evenly across all child vdevs; usually, dcols is * the number of children in the target vdev. * * Avoid inlining the function to keep vdev_raidz_io_start(), which * is this functions only caller, as small as possible on the stack. */ noinline raidz_map_t * vdev_raidz_map_alloc(zio_t *zio, uint64_t ashift, uint64_t dcols, uint64_t nparity) { raidz_row_t *rr; /* The starting RAIDZ (parent) vdev sector of the block. */ uint64_t b = zio->io_offset >> ashift; /* The zio's size in units of the vdev's minimum sector size. */ uint64_t s = zio->io_size >> ashift; /* The first column for this stripe. */ uint64_t f = b % dcols; /* The starting byte offset on each child vdev. */ uint64_t o = (b / dcols) << ashift; uint64_t q, r, c, bc, col, acols, scols, coff, devidx, asize, tot; raidz_map_t *rm = kmem_zalloc(offsetof(raidz_map_t, rm_row[1]), KM_SLEEP); rm->rm_nrows = 1; /* * "Quotient": The number of data sectors for this stripe on all but * the "big column" child vdevs that also contain "remainder" data. */ q = s / (dcols - nparity); /* * "Remainder": The number of partial stripe data sectors in this I/O. * This will add a sector to some, but not all, child vdevs. */ r = s - q * (dcols - nparity); /* The number of "big columns" - those which contain remainder data. */ bc = (r == 0 ? 0 : r + nparity); /* * The total number of data and parity sectors associated with * this I/O. */ tot = s + nparity * (q + (r == 0 ? 0 : 1)); /* * acols: The columns that will be accessed. * scols: The columns that will be accessed or skipped. */ if (q == 0) { /* Our I/O request doesn't span all child vdevs. */ acols = bc; scols = MIN(dcols, roundup(bc, nparity + 1)); } else { acols = dcols; scols = dcols; } ASSERT3U(acols, <=, scols); rr = kmem_alloc(offsetof(raidz_row_t, rr_col[scols]), KM_SLEEP); rm->rm_row[0] = rr; rr->rr_cols = acols; rr->rr_scols = scols; rr->rr_bigcols = bc; rr->rr_missingdata = 0; rr->rr_missingparity = 0; rr->rr_firstdatacol = nparity; rr->rr_abd_empty = NULL; rr->rr_nempty = 0; #ifdef ZFS_DEBUG rr->rr_offset = zio->io_offset; rr->rr_size = zio->io_size; #endif asize = 0; for (c = 0; c < scols; c++) { raidz_col_t *rc = &rr->rr_col[c]; col = f + c; coff = o; if (col >= dcols) { col -= dcols; coff += 1ULL << ashift; } rc->rc_devidx = col; rc->rc_offset = coff; rc->rc_abd = NULL; rc->rc_orig_data = NULL; rc->rc_error = 0; rc->rc_tried = 0; rc->rc_skipped = 0; rc->rc_force_repair = 0; rc->rc_allow_repair = 1; rc->rc_need_orig_restore = B_FALSE; if (c >= acols) rc->rc_size = 0; else if (c < bc) rc->rc_size = (q + 1) << ashift; else rc->rc_size = q << ashift; asize += rc->rc_size; } ASSERT3U(asize, ==, tot << ashift); rm->rm_nskip = roundup(tot, nparity + 1) - tot; rm->rm_skipstart = bc; /* * 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 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. * * If we intend to skip a sector in the zeroth column for padding * we must make sure to note this swap. We will never intend to * skip the first column since at least one data and one parity * column must appear in each row. */ ASSERT(rr->rr_cols >= 2); ASSERT(rr->rr_col[0].rc_size == rr->rr_col[1].rc_size); if (rr->rr_firstdatacol == 1 && (zio->io_offset & (1ULL << 20))) { devidx = rr->rr_col[0].rc_devidx; o = rr->rr_col[0].rc_offset; rr->rr_col[0].rc_devidx = rr->rr_col[1].rc_devidx; rr->rr_col[0].rc_offset = rr->rr_col[1].rc_offset; rr->rr_col[1].rc_devidx = devidx; rr->rr_col[1].rc_offset = o; if (rm->rm_skipstart == 0) rm->rm_skipstart = 1; } if (zio->io_type == ZIO_TYPE_WRITE) { vdev_raidz_map_alloc_write(zio, rm, ashift); } else { vdev_raidz_map_alloc_read(zio, rm); } /* init RAIDZ parity ops */ rm->rm_ops = vdev_raidz_math_get_ops(); return (rm); } struct pqr_struct { uint64_t *p; uint64_t *q; uint64_t *r; }; static int vdev_raidz_p_func(void *buf, size_t size, void *private) { struct pqr_struct *pqr = private; const uint64_t *src = buf; int i, cnt = size / sizeof (src[0]); ASSERT(pqr->p && !pqr->q && !pqr->r); for (i = 0; i < cnt; i++, src++, pqr->p++) *pqr->p ^= *src; return (0); } static int vdev_raidz_pq_func(void *buf, size_t size, void *private) { struct pqr_struct *pqr = private; const uint64_t *src = buf; uint64_t mask; int i, cnt = size / sizeof (src[0]); ASSERT(pqr->p && pqr->q && !pqr->r); for (i = 0; i < cnt; i++, src++, pqr->p++, pqr->q++) { *pqr->p ^= *src; VDEV_RAIDZ_64MUL_2(*pqr->q, mask); *pqr->q ^= *src; } return (0); } static int vdev_raidz_pqr_func(void *buf, size_t size, void *private) { struct pqr_struct *pqr = private; const uint64_t *src = buf; uint64_t mask; int i, cnt = size / sizeof (src[0]); ASSERT(pqr->p && pqr->q && pqr->r); for (i = 0; i < cnt; i++, src++, pqr->p++, pqr->q++, pqr->r++) { *pqr->p ^= *src; VDEV_RAIDZ_64MUL_2(*pqr->q, mask); *pqr->q ^= *src; VDEV_RAIDZ_64MUL_4(*pqr->r, mask); *pqr->r ^= *src; } return (0); } static void vdev_raidz_generate_parity_p(raidz_row_t *rr) { uint64_t *p = abd_to_buf(rr->rr_col[VDEV_RAIDZ_P].rc_abd); for (int c = rr->rr_firstdatacol; c < rr->rr_cols; c++) { abd_t *src = rr->rr_col[c].rc_abd; if (c == rr->rr_firstdatacol) { abd_copy_to_buf(p, src, rr->rr_col[c].rc_size); } else { struct pqr_struct pqr = { p, NULL, NULL }; (void) abd_iterate_func(src, 0, rr->rr_col[c].rc_size, vdev_raidz_p_func, &pqr); } } } static void vdev_raidz_generate_parity_pq(raidz_row_t *rr) { uint64_t *p = abd_to_buf(rr->rr_col[VDEV_RAIDZ_P].rc_abd); uint64_t *q = abd_to_buf(rr->rr_col[VDEV_RAIDZ_Q].rc_abd); uint64_t pcnt = rr->rr_col[VDEV_RAIDZ_P].rc_size / sizeof (p[0]); ASSERT(rr->rr_col[VDEV_RAIDZ_P].rc_size == rr->rr_col[VDEV_RAIDZ_Q].rc_size); for (int c = rr->rr_firstdatacol; c < rr->rr_cols; c++) { abd_t *src = rr->rr_col[c].rc_abd; uint64_t ccnt = rr->rr_col[c].rc_size / sizeof (p[0]); if (c == rr->rr_firstdatacol) { ASSERT(ccnt == pcnt || ccnt == 0); abd_copy_to_buf(p, src, rr->rr_col[c].rc_size); (void) memcpy(q, p, rr->rr_col[c].rc_size); for (uint64_t i = ccnt; i < pcnt; i++) { p[i] = 0; q[i] = 0; } } else { struct pqr_struct pqr = { p, q, NULL }; ASSERT(ccnt <= pcnt); (void) abd_iterate_func(src, 0, rr->rr_col[c].rc_size, vdev_raidz_pq_func, &pqr); /* * Treat short columns as though they are full of 0s. * Note that there's therefore nothing needed for P. */ uint64_t mask; for (uint64_t i = ccnt; i < pcnt; i++) { VDEV_RAIDZ_64MUL_2(q[i], mask); } } } } static void vdev_raidz_generate_parity_pqr(raidz_row_t *rr) { uint64_t *p = abd_to_buf(rr->rr_col[VDEV_RAIDZ_P].rc_abd); uint64_t *q = abd_to_buf(rr->rr_col[VDEV_RAIDZ_Q].rc_abd); uint64_t *r = abd_to_buf(rr->rr_col[VDEV_RAIDZ_R].rc_abd); uint64_t pcnt = rr->rr_col[VDEV_RAIDZ_P].rc_size / sizeof (p[0]); ASSERT(rr->rr_col[VDEV_RAIDZ_P].rc_size == rr->rr_col[VDEV_RAIDZ_Q].rc_size); ASSERT(rr->rr_col[VDEV_RAIDZ_P].rc_size == rr->rr_col[VDEV_RAIDZ_R].rc_size); for (int c = rr->rr_firstdatacol; c < rr->rr_cols; c++) { abd_t *src = rr->rr_col[c].rc_abd; uint64_t ccnt = rr->rr_col[c].rc_size / sizeof (p[0]); if (c == rr->rr_firstdatacol) { ASSERT(ccnt == pcnt || ccnt == 0); abd_copy_to_buf(p, src, rr->rr_col[c].rc_size); (void) memcpy(q, p, rr->rr_col[c].rc_size); (void) memcpy(r, p, rr->rr_col[c].rc_size); for (uint64_t i = ccnt; i < pcnt; i++) { p[i] = 0; q[i] = 0; r[i] = 0; } } else { struct pqr_struct pqr = { p, q, r }; ASSERT(ccnt <= pcnt); (void) abd_iterate_func(src, 0, rr->rr_col[c].rc_size, vdev_raidz_pqr_func, &pqr); /* * Treat short columns as though they are full of 0s. * Note that there's therefore nothing needed for P. */ uint64_t mask; for (uint64_t i = ccnt; i < pcnt; i++) { VDEV_RAIDZ_64MUL_2(q[i], mask); VDEV_RAIDZ_64MUL_4(r[i], mask); } } } } /* * Generate RAID parity in the first virtual columns according to the number of * parity columns available. */ void vdev_raidz_generate_parity_row(raidz_map_t *rm, raidz_row_t *rr) { ASSERT3U(rr->rr_cols, !=, 0); /* Generate using the new math implementation */ if (vdev_raidz_math_generate(rm, rr) != RAIDZ_ORIGINAL_IMPL) return; switch (rr->rr_firstdatacol) { case 1: vdev_raidz_generate_parity_p(rr); break; case 2: vdev_raidz_generate_parity_pq(rr); break; case 3: vdev_raidz_generate_parity_pqr(rr); break; default: cmn_err(CE_PANIC, "invalid RAID-Z configuration"); } } void vdev_raidz_generate_parity(raidz_map_t *rm) { for (int i = 0; i < rm->rm_nrows; i++) { raidz_row_t *rr = rm->rm_row[i]; vdev_raidz_generate_parity_row(rm, rr); } } static int vdev_raidz_reconst_p_func(void *dbuf, void *sbuf, size_t size, void *private) { (void) private; uint64_t *dst = dbuf; uint64_t *src = sbuf; int cnt = size / sizeof (src[0]); for (int i = 0; i < cnt; i++) { dst[i] ^= src[i]; } return (0); } static int vdev_raidz_reconst_q_pre_func(void *dbuf, void *sbuf, size_t size, void *private) { (void) private; uint64_t *dst = dbuf; uint64_t *src = sbuf; uint64_t mask; int cnt = size / sizeof (dst[0]); for (int i = 0; i < cnt; i++, dst++, src++) { VDEV_RAIDZ_64MUL_2(*dst, mask); *dst ^= *src; } return (0); } static int vdev_raidz_reconst_q_pre_tail_func(void *buf, size_t size, void *private) { (void) private; uint64_t *dst = buf; uint64_t mask; int cnt = size / sizeof (dst[0]); for (int i = 0; i < cnt; i++, dst++) { /* same operation as vdev_raidz_reconst_q_pre_func() on dst */ VDEV_RAIDZ_64MUL_2(*dst, mask); } return (0); } struct reconst_q_struct { uint64_t *q; int exp; }; static int vdev_raidz_reconst_q_post_func(void *buf, size_t size, void *private) { struct reconst_q_struct *rq = private; uint64_t *dst = buf; int cnt = size / sizeof (dst[0]); for (int i = 0; i < cnt; i++, dst++, rq->q++) { int j; uint8_t *b; *dst ^= *rq->q; for (j = 0, b = (uint8_t *)dst; j < 8; j++, b++) { *b = vdev_raidz_exp2(*b, rq->exp); } } return (0); } struct reconst_pq_struct { uint8_t *p; uint8_t *q; uint8_t *pxy; uint8_t *qxy; int aexp; int bexp; }; static int vdev_raidz_reconst_pq_func(void *xbuf, void *ybuf, size_t size, void *private) { struct reconst_pq_struct *rpq = private; uint8_t *xd = xbuf; uint8_t *yd = ybuf; for (int i = 0; i < size; i++, rpq->p++, rpq->q++, rpq->pxy++, rpq->qxy++, xd++, yd++) { *xd = vdev_raidz_exp2(*rpq->p ^ *rpq->pxy, rpq->aexp) ^ vdev_raidz_exp2(*rpq->q ^ *rpq->qxy, rpq->bexp); *yd = *rpq->p ^ *rpq->pxy ^ *xd; } return (0); } static int vdev_raidz_reconst_pq_tail_func(void *xbuf, size_t size, void *private) { struct reconst_pq_struct *rpq = private; uint8_t *xd = xbuf; for (int i = 0; i < size; i++, rpq->p++, rpq->q++, rpq->pxy++, rpq->qxy++, xd++) { /* same operation as vdev_raidz_reconst_pq_func() on xd */ *xd = vdev_raidz_exp2(*rpq->p ^ *rpq->pxy, rpq->aexp) ^ vdev_raidz_exp2(*rpq->q ^ *rpq->qxy, rpq->bexp); } return (0); } static void vdev_raidz_reconstruct_p(raidz_row_t *rr, int *tgts, int ntgts) { int x = tgts[0]; abd_t *dst, *src; ASSERT3U(ntgts, ==, 1); ASSERT3U(x, >=, rr->rr_firstdatacol); ASSERT3U(x, <, rr->rr_cols); ASSERT3U(rr->rr_col[x].rc_size, <=, rr->rr_col[VDEV_RAIDZ_P].rc_size); src = rr->rr_col[VDEV_RAIDZ_P].rc_abd; dst = rr->rr_col[x].rc_abd; abd_copy_from_buf(dst, abd_to_buf(src), rr->rr_col[x].rc_size); for (int c = rr->rr_firstdatacol; c < rr->rr_cols; c++) { uint64_t size = MIN(rr->rr_col[x].rc_size, rr->rr_col[c].rc_size); src = rr->rr_col[c].rc_abd; if (c == x) continue; (void) abd_iterate_func2(dst, src, 0, 0, size, vdev_raidz_reconst_p_func, NULL); } } static void vdev_raidz_reconstruct_q(raidz_row_t *rr, int *tgts, int ntgts) { int x = tgts[0]; int c, exp; abd_t *dst, *src; ASSERT(ntgts == 1); ASSERT(rr->rr_col[x].rc_size <= rr->rr_col[VDEV_RAIDZ_Q].rc_size); for (c = rr->rr_firstdatacol; c < rr->rr_cols; c++) { uint64_t size = (c == x) ? 0 : MIN(rr->rr_col[x].rc_size, rr->rr_col[c].rc_size); src = rr->rr_col[c].rc_abd; dst = rr->rr_col[x].rc_abd; if (c == rr->rr_firstdatacol) { abd_copy(dst, src, size); if (rr->rr_col[x].rc_size > size) { abd_zero_off(dst, size, rr->rr_col[x].rc_size - size); } } else { ASSERT3U(size, <=, rr->rr_col[x].rc_size); (void) abd_iterate_func2(dst, src, 0, 0, size, vdev_raidz_reconst_q_pre_func, NULL); (void) abd_iterate_func(dst, size, rr->rr_col[x].rc_size - size, vdev_raidz_reconst_q_pre_tail_func, NULL); } } src = rr->rr_col[VDEV_RAIDZ_Q].rc_abd; dst = rr->rr_col[x].rc_abd; exp = 255 - (rr->rr_cols - 1 - x); struct reconst_q_struct rq = { abd_to_buf(src), exp }; (void) abd_iterate_func(dst, 0, rr->rr_col[x].rc_size, vdev_raidz_reconst_q_post_func, &rq); } static void vdev_raidz_reconstruct_pq(raidz_row_t *rr, int *tgts, int ntgts) { uint8_t *p, *q, *pxy, *qxy, tmp, a, b, aexp, bexp; abd_t *pdata, *qdata; uint64_t xsize, ysize; int x = tgts[0]; int y = tgts[1]; abd_t *xd, *yd; ASSERT(ntgts == 2); ASSERT(x < y); ASSERT(x >= rr->rr_firstdatacol); ASSERT(y < rr->rr_cols); ASSERT(rr->rr_col[x].rc_size >= rr->rr_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 = rr->rr_col[VDEV_RAIDZ_P].rc_abd; qdata = rr->rr_col[VDEV_RAIDZ_Q].rc_abd; xsize = rr->rr_col[x].rc_size; ysize = rr->rr_col[y].rc_size; rr->rr_col[VDEV_RAIDZ_P].rc_abd = abd_alloc_linear(rr->rr_col[VDEV_RAIDZ_P].rc_size, B_TRUE); rr->rr_col[VDEV_RAIDZ_Q].rc_abd = abd_alloc_linear(rr->rr_col[VDEV_RAIDZ_Q].rc_size, B_TRUE); rr->rr_col[x].rc_size = 0; rr->rr_col[y].rc_size = 0; vdev_raidz_generate_parity_pq(rr); rr->rr_col[x].rc_size = xsize; rr->rr_col[y].rc_size = ysize; p = abd_to_buf(pdata); q = abd_to_buf(qdata); pxy = abd_to_buf(rr->rr_col[VDEV_RAIDZ_P].rc_abd); qxy = abd_to_buf(rr->rr_col[VDEV_RAIDZ_Q].rc_abd); xd = rr->rr_col[x].rc_abd; yd = rr->rr_col[y].rc_abd; /* * 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 - (rr->rr_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)]; ASSERT3U(xsize, >=, ysize); struct reconst_pq_struct rpq = { p, q, pxy, qxy, aexp, bexp }; (void) abd_iterate_func2(xd, yd, 0, 0, ysize, vdev_raidz_reconst_pq_func, &rpq); (void) abd_iterate_func(xd, ysize, xsize - ysize, vdev_raidz_reconst_pq_tail_func, &rpq); abd_free(rr->rr_col[VDEV_RAIDZ_P].rc_abd); abd_free(rr->rr_col[VDEV_RAIDZ_Q].rc_abd); /* * Restore the saved parity data. */ rr->rr_col[VDEV_RAIDZ_P].rc_abd = pdata; rr->rr_col[VDEV_RAIDZ_Q].rc_abd = qdata; } /* * In the general case of reconstruction, we must solve the system of linear * equations defined by the coefficients used to generate parity as well as * the contents of the data and parity disks. This can be expressed with * vectors for the original data (D) and the actual data (d) and parity (p) * and a matrix composed of the identity matrix (I) and a dispersal matrix (V): * * __ __ __ __ * | | __ __ | p_0 | * | V | | D_0 | | p_m-1 | * | | x | : | = | d_0 | * | I | | D_n-1 | | : | * | | ~~ ~~ | d_n-1 | * ~~ ~~ ~~ ~~ * * I is simply a square identity matrix of size n, and V is a vandermonde * matrix defined by the coefficients we chose for the various parity columns * (1, 2, 4). Note that these values were chosen both for simplicity, speedy * computation as well as linear separability. * * __ __ __ __ * | 1 .. 1 1 1 | | p_0 | * | 2^n-1 .. 4 2 1 | __ __ | : | * | 4^n-1 .. 16 4 1 | | D_0 | | p_m-1 | * | 1 .. 0 0 0 | | D_1 | | d_0 | * | 0 .. 0 0 0 | x | D_2 | = | d_1 | * | : : : : | | : | | d_2 | * | 0 .. 1 0 0 | | D_n-1 | | : | * | 0 .. 0 1 0 | ~~ ~~ | : | * | 0 .. 0 0 1 | | d_n-1 | * ~~ ~~ ~~ ~~ * * Note that I, V, d, and p are known. To compute D, we must invert the * matrix and use the known data and parity values to reconstruct the unknown * data values. We begin by removing the rows in V|I and d|p that correspond * to failed or missing columns; we then make V|I square (n x n) and d|p * sized n by removing rows corresponding to unused parity from the bottom up * to generate (V|I)' and (d|p)'. We can then generate the inverse of (V|I)' * using Gauss-Jordan elimination. In the example below we use m=3 parity * columns, n=8 data columns, with errors in d_1, d_2, and p_1: * __ __ * | 1 1 1 1 1 1 1 1 | * | 128 64 32 16 8 4 2 1 | <-----+-+-- missing disks * | 19 205 116 29 64 16 4 1 | / / * | 1 0 0 0 0 0 0 0 | / / * | 0 1 0 0 0 0 0 0 | <--' / * (V|I) = | 0 0 1 0 0 0 0 0 | <---' * | 0 0 0 1 0 0 0 0 | * | 0 0 0 0 1 0 0 0 | * | 0 0 0 0 0 1 0 0 | * | 0 0 0 0 0 0 1 0 | * | 0 0 0 0 0 0 0 1 | * ~~ ~~ * __ __ * | 1 1 1 1 1 1 1 1 | * | 128 64 32 16 8 4 2 1 | * | 19 205 116 29 64 16 4 1 | * | 1 0 0 0 0 0 0 0 | * | 0 1 0 0 0 0 0 0 | * (V|I)' = | 0 0 1 0 0 0 0 0 | * | 0 0 0 1 0 0 0 0 | * | 0 0 0 0 1 0 0 0 | * | 0 0 0 0 0 1 0 0 | * | 0 0 0 0 0 0 1 0 | * | 0 0 0 0 0 0 0 1 | * ~~ ~~ * * Here we employ Gauss-Jordan elimination to find the inverse of (V|I)'. We * have carefully chosen the seed values 1, 2, and 4 to ensure that this * matrix is not singular. * __ __ * | 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 | * | 19 205 116 29 64 16 4 1 0 1 0 0 0 0 0 0 | * | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 | * | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 | * | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 | * | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 | * | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 | * | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 | * ~~ ~~ * __ __ * | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 | * | 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 | * | 19 205 116 29 64 16 4 1 0 1 0 0 0 0 0 0 | * | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 | * | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 | * | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 | * | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 | * | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 | * ~~ ~~ * __ __ * | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 | * | 0 1 1 0 0 0 0 0 1 0 1 1 1 1 1 1 | * | 0 205 116 0 0 0 0 0 0 1 19 29 64 16 4 1 | * | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 | * | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 | * | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 | * | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 | * | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 | * ~~ ~~ * __ __ * | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 | * | 0 1 1 0 0 0 0 0 1 0 1 1 1 1 1 1 | * | 0 0 185 0 0 0 0 0 205 1 222 208 141 221 201 204 | * | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 | * | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 | * | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 | * | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 | * | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 | * ~~ ~~ * __ __ * | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 | * | 0 1 1 0 0 0 0 0 1 0 1 1 1 1 1 1 | * | 0 0 1 0 0 0 0 0 166 100 4 40 158 168 216 209 | * | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 | * | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 | * | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 | * | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 | * | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 | * ~~ ~~ * __ __ * | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 | * | 0 1 0 0 0 0 0 0 167 100 5 41 159 169 217 208 | * | 0 0 1 0 0 0 0 0 166 100 4 40 158 168 216 209 | * | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 | * | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 | * | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 | * | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 | * | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 | * ~~ ~~ * __ __ * | 0 0 1 0 0 0 0 0 | * | 167 100 5 41 159 169 217 208 | * | 166 100 4 40 158 168 216 209 | * (V|I)'^-1 = | 0 0 0 1 0 0 0 0 | * | 0 0 0 0 1 0 0 0 | * | 0 0 0 0 0 1 0 0 | * | 0 0 0 0 0 0 1 0 | * | 0 0 0 0 0 0 0 1 | * ~~ ~~ * * We can then simply compute D = (V|I)'^-1 x (d|p)' to discover the values * of the missing data. * * As is apparent from the example above, the only non-trivial rows in the * inverse matrix correspond to the data disks that we're trying to * reconstruct. Indeed, those are the only rows we need as the others would * only be useful for reconstructing data known or assumed to be valid. For * that reason, we only build the coefficients in the rows that correspond to * targeted columns. */ static void vdev_raidz_matrix_init(raidz_row_t *rr, int n, int nmap, int *map, uint8_t **rows) { int i, j; int pow; ASSERT(n == rr->rr_cols - rr->rr_firstdatacol); /* * Fill in the missing rows of interest. */ for (i = 0; i < nmap; i++) { ASSERT3S(0, <=, map[i]); ASSERT3S(map[i], <=, 2); pow = map[i] * n; if (pow > 255) pow -= 255; ASSERT(pow <= 255); for (j = 0; j < n; j++) { pow -= map[i]; if (pow < 0) pow += 255; rows[i][j] = vdev_raidz_pow2[pow]; } } } static void vdev_raidz_matrix_invert(raidz_row_t *rr, int n, int nmissing, int *missing, uint8_t **rows, uint8_t **invrows, const uint8_t *used) { int i, j, ii, jj; uint8_t log; /* * Assert that the first nmissing entries from the array of used * columns correspond to parity columns and that subsequent entries * correspond to data columns. */ for (i = 0; i < nmissing; i++) { ASSERT3S(used[i], <, rr->rr_firstdatacol); } for (; i < n; i++) { ASSERT3S(used[i], >=, rr->rr_firstdatacol); } /* * First initialize the storage where we'll compute the inverse rows. */ for (i = 0; i < nmissing; i++) { for (j = 0; j < n; j++) { invrows[i][j] = (i == j) ? 1 : 0; } } /* * Subtract all trivial rows from the rows of consequence. */ for (i = 0; i < nmissing; i++) { for (j = nmissing; j < n; j++) { ASSERT3U(used[j], >=, rr->rr_firstdatacol); jj = used[j] - rr->rr_firstdatacol; ASSERT3S(jj, <, n); invrows[i][j] = rows[i][jj]; rows[i][jj] = 0; } } /* * For each of the rows of interest, we must normalize it and subtract * a multiple of it from the other rows. */ for (i = 0; i < nmissing; i++) { for (j = 0; j < missing[i]; j++) { ASSERT0(rows[i][j]); } ASSERT3U(rows[i][missing[i]], !=, 0); /* * Compute the inverse of the first element and multiply each * element in the row by that value. */ log = 255 - vdev_raidz_log2[rows[i][missing[i]]]; for (j = 0; j < n; j++) { rows[i][j] = vdev_raidz_exp2(rows[i][j], log); invrows[i][j] = vdev_raidz_exp2(invrows[i][j], log); } for (ii = 0; ii < nmissing; ii++) { if (i == ii) continue; ASSERT3U(rows[ii][missing[i]], !=, 0); log = vdev_raidz_log2[rows[ii][missing[i]]]; for (j = 0; j < n; j++) { rows[ii][j] ^= vdev_raidz_exp2(rows[i][j], log); invrows[ii][j] ^= vdev_raidz_exp2(invrows[i][j], log); } } } /* * Verify that the data that is left in the rows are properly part of * an identity matrix. */ for (i = 0; i < nmissing; i++) { for (j = 0; j < n; j++) { if (j == missing[i]) { ASSERT3U(rows[i][j], ==, 1); } else { ASSERT0(rows[i][j]); } } } } static void vdev_raidz_matrix_reconstruct(raidz_row_t *rr, int n, int nmissing, int *missing, uint8_t **invrows, const uint8_t *used) { int i, j, x, cc, c; uint8_t *src; uint64_t ccount; uint8_t *dst[VDEV_RAIDZ_MAXPARITY] = { NULL }; uint64_t dcount[VDEV_RAIDZ_MAXPARITY] = { 0 }; uint8_t log = 0; uint8_t val; int ll; uint8_t *invlog[VDEV_RAIDZ_MAXPARITY]; uint8_t *p, *pp; size_t psize; psize = sizeof (invlog[0][0]) * n * nmissing; p = kmem_alloc(psize, KM_SLEEP); for (pp = p, i = 0; i < nmissing; i++) { invlog[i] = pp; pp += n; } for (i = 0; i < nmissing; i++) { for (j = 0; j < n; j++) { ASSERT3U(invrows[i][j], !=, 0); invlog[i][j] = vdev_raidz_log2[invrows[i][j]]; } } for (i = 0; i < n; i++) { c = used[i]; ASSERT3U(c, <, rr->rr_cols); ccount = rr->rr_col[c].rc_size; ASSERT(ccount >= rr->rr_col[missing[0]].rc_size || i > 0); if (ccount == 0) continue; src = abd_to_buf(rr->rr_col[c].rc_abd); for (j = 0; j < nmissing; j++) { cc = missing[j] + rr->rr_firstdatacol; ASSERT3U(cc, >=, rr->rr_firstdatacol); ASSERT3U(cc, <, rr->rr_cols); ASSERT3U(cc, !=, c); dcount[j] = rr->rr_col[cc].rc_size; if (dcount[j] != 0) dst[j] = abd_to_buf(rr->rr_col[cc].rc_abd); } for (x = 0; x < ccount; x++, src++) { if (*src != 0) log = vdev_raidz_log2[*src]; for (cc = 0; cc < nmissing; cc++) { if (x >= dcount[cc]) continue; if (*src == 0) { val = 0; } else { if ((ll = log + invlog[cc][i]) >= 255) ll -= 255; val = vdev_raidz_pow2[ll]; } if (i == 0) dst[cc][x] = val; else dst[cc][x] ^= val; } } } kmem_free(p, psize); } static void vdev_raidz_reconstruct_general(raidz_row_t *rr, int *tgts, int ntgts) { int n, i, c, t, tt; int nmissing_rows; int missing_rows[VDEV_RAIDZ_MAXPARITY]; int parity_map[VDEV_RAIDZ_MAXPARITY]; uint8_t *p, *pp; size_t psize; uint8_t *rows[VDEV_RAIDZ_MAXPARITY]; uint8_t *invrows[VDEV_RAIDZ_MAXPARITY]; uint8_t *used; abd_t **bufs = NULL; /* * Matrix reconstruction can't use scatter ABDs yet, so we allocate * temporary linear ABDs if any non-linear ABDs are found. */ for (i = rr->rr_firstdatacol; i < rr->rr_cols; i++) { if (!abd_is_linear(rr->rr_col[i].rc_abd)) { bufs = kmem_alloc(rr->rr_cols * sizeof (abd_t *), KM_PUSHPAGE); for (c = rr->rr_firstdatacol; c < rr->rr_cols; c++) { raidz_col_t *col = &rr->rr_col[c]; bufs[c] = col->rc_abd; if (bufs[c] != NULL) { col->rc_abd = abd_alloc_linear( col->rc_size, B_TRUE); abd_copy(col->rc_abd, bufs[c], col->rc_size); } } break; } } n = rr->rr_cols - rr->rr_firstdatacol; /* * Figure out which data columns are missing. */ nmissing_rows = 0; for (t = 0; t < ntgts; t++) { if (tgts[t] >= rr->rr_firstdatacol) { missing_rows[nmissing_rows++] = tgts[t] - rr->rr_firstdatacol; } } /* * Figure out which parity columns to use to help generate the missing * data columns. */ for (tt = 0, c = 0, i = 0; i < nmissing_rows; c++) { ASSERT(tt < ntgts); ASSERT(c < rr->rr_firstdatacol); /* * Skip any targeted parity columns. */ if (c == tgts[tt]) { tt++; continue; } parity_map[i] = c; i++; } psize = (sizeof (rows[0][0]) + sizeof (invrows[0][0])) * nmissing_rows * n + sizeof (used[0]) * n; p = kmem_alloc(psize, KM_SLEEP); for (pp = p, i = 0; i < nmissing_rows; i++) { rows[i] = pp; pp += n; invrows[i] = pp; pp += n; } used = pp; for (i = 0; i < nmissing_rows; i++) { used[i] = parity_map[i]; } for (tt = 0, c = rr->rr_firstdatacol; c < rr->rr_cols; c++) { if (tt < nmissing_rows && c == missing_rows[tt] + rr->rr_firstdatacol) { tt++; continue; } ASSERT3S(i, <, n); used[i] = c; i++; } /* * Initialize the interesting rows of the matrix. */ vdev_raidz_matrix_init(rr, n, nmissing_rows, parity_map, rows); /* * Invert the matrix. */ vdev_raidz_matrix_invert(rr, n, nmissing_rows, missing_rows, rows, invrows, used); /* * Reconstruct the missing data using the generated matrix. */ vdev_raidz_matrix_reconstruct(rr, n, nmissing_rows, missing_rows, invrows, used); kmem_free(p, psize); /* * copy back from temporary linear abds and free them */ if (bufs) { for (c = rr->rr_firstdatacol; c < rr->rr_cols; c++) { raidz_col_t *col = &rr->rr_col[c]; if (bufs[c] != NULL) { abd_copy(bufs[c], col->rc_abd, col->rc_size); abd_free(col->rc_abd); } col->rc_abd = bufs[c]; } kmem_free(bufs, rr->rr_cols * sizeof (abd_t *)); } } static void vdev_raidz_reconstruct_row(raidz_map_t *rm, raidz_row_t *rr, const int *t, int nt) { int tgts[VDEV_RAIDZ_MAXPARITY], *dt; int ntgts; int i, c, ret; int nbadparity, nbaddata; int parity_valid[VDEV_RAIDZ_MAXPARITY]; nbadparity = rr->rr_firstdatacol; nbaddata = rr->rr_cols - nbadparity; ntgts = 0; for (i = 0, c = 0; c < rr->rr_cols; c++) { if (c < rr->rr_firstdatacol) parity_valid[c] = B_FALSE; if (i < nt && c == t[i]) { tgts[ntgts++] = c; i++; } else if (rr->rr_col[c].rc_error != 0) { tgts[ntgts++] = c; } else if (c >= rr->rr_firstdatacol) { nbaddata--; } else { parity_valid[c] = B_TRUE; nbadparity--; } } ASSERT(ntgts >= nt); ASSERT(nbaddata >= 0); ASSERT(nbaddata + nbadparity == ntgts); dt = &tgts[nbadparity]; /* Reconstruct using the new math implementation */ ret = vdev_raidz_math_reconstruct(rm, rr, parity_valid, dt, nbaddata); if (ret != RAIDZ_ORIGINAL_IMPL) return; /* * See if we can use any of our optimized reconstruction routines. */ switch (nbaddata) { case 1: if (parity_valid[VDEV_RAIDZ_P]) { vdev_raidz_reconstruct_p(rr, dt, 1); return; } ASSERT(rr->rr_firstdatacol > 1); if (parity_valid[VDEV_RAIDZ_Q]) { vdev_raidz_reconstruct_q(rr, dt, 1); return; } ASSERT(rr->rr_firstdatacol > 2); break; case 2: ASSERT(rr->rr_firstdatacol > 1); if (parity_valid[VDEV_RAIDZ_P] && parity_valid[VDEV_RAIDZ_Q]) { vdev_raidz_reconstruct_pq(rr, dt, 2); return; } ASSERT(rr->rr_firstdatacol > 2); break; } vdev_raidz_reconstruct_general(rr, tgts, ntgts); } static int vdev_raidz_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize, uint64_t *logical_ashift, uint64_t *physical_ashift) { vdev_raidz_t *vdrz = vd->vdev_tsd; uint64_t nparity = vdrz->vd_nparity; int c; 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 (SET_ERROR(EINVAL)); } vdev_open_children(vd); for (c = 0; c < vd->vdev_children; c++) { vdev_t *cvd = vd->vdev_child[c]; if (cvd->vdev_open_error != 0) { lasterror = cvd->vdev_open_error; numerrors++; continue; } *asize = MIN(*asize - 1, cvd->vdev_asize - 1) + 1; *max_asize = MIN(*max_asize - 1, cvd->vdev_max_asize - 1) + 1; *logical_ashift = MAX(*logical_ashift, cvd->vdev_ashift); } for (c = 0; c < vd->vdev_children; c++) { vdev_t *cvd = vd->vdev_child[c]; if (cvd->vdev_open_error != 0) continue; *physical_ashift = vdev_best_ashift(*logical_ashift, *physical_ashift, cvd->vdev_physical_ashift); } *asize *= vd->vdev_children; *max_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) { for (int c = 0; c < vd->vdev_children; c++) { if (vd->vdev_child[c] != NULL) vdev_close(vd->vdev_child[c]); } } static uint64_t vdev_raidz_asize(vdev_t *vd, uint64_t psize) { vdev_raidz_t *vdrz = vd->vdev_tsd; uint64_t asize; uint64_t ashift = vd->vdev_top->vdev_ashift; uint64_t cols = vdrz->vd_logical_width; uint64_t nparity = vdrz->vd_nparity; asize = ((psize - 1) >> ashift) + 1; asize += nparity * ((asize + cols - nparity - 1) / (cols - nparity)); asize = roundup(asize, nparity + 1) << ashift; return (asize); } /* * The allocatable space for a raidz vdev is N * sizeof(smallest child) * so each child must provide at least 1/Nth of its asize. */ static uint64_t vdev_raidz_min_asize(vdev_t *vd) { return ((vd->vdev_min_asize + vd->vdev_children - 1) / vd->vdev_children); } void vdev_raidz_child_done(zio_t *zio) { raidz_col_t *rc = zio->io_private; ASSERT3P(rc->rc_abd, !=, NULL); rc->rc_error = zio->io_error; rc->rc_tried = 1; rc->rc_skipped = 0; } static void vdev_raidz_io_verify(vdev_t *vd, raidz_row_t *rr, int col) { #ifdef ZFS_DEBUG vdev_t *tvd = vd->vdev_top; range_seg64_t logical_rs, physical_rs, remain_rs; logical_rs.rs_start = rr->rr_offset; logical_rs.rs_end = logical_rs.rs_start + vdev_raidz_asize(vd, rr->rr_size); raidz_col_t *rc = &rr->rr_col[col]; vdev_t *cvd = vd->vdev_child[rc->rc_devidx]; vdev_xlate(cvd, &logical_rs, &physical_rs, &remain_rs); ASSERT(vdev_xlate_is_empty(&remain_rs)); ASSERT3U(rc->rc_offset, ==, physical_rs.rs_start); ASSERT3U(rc->rc_offset, <, physical_rs.rs_end); /* * It would be nice to assert that rs_end is equal * to rc_offset + rc_size but there might be an * optional I/O at the end that is not accounted in * rc_size. */ if (physical_rs.rs_end > rc->rc_offset + rc->rc_size) { ASSERT3U(physical_rs.rs_end, ==, rc->rc_offset + rc->rc_size + (1 << tvd->vdev_ashift)); } else { ASSERT3U(physical_rs.rs_end, ==, rc->rc_offset + rc->rc_size); } #endif } static void vdev_raidz_io_start_write(zio_t *zio, raidz_row_t *rr, uint64_t ashift) { vdev_t *vd = zio->io_vd; raidz_map_t *rm = zio->io_vsd; vdev_raidz_generate_parity_row(rm, rr); for (int c = 0; c < rr->rr_scols; c++) { raidz_col_t *rc = &rr->rr_col[c]; vdev_t *cvd = vd->vdev_child[rc->rc_devidx]; /* Verify physical to logical translation */ vdev_raidz_io_verify(vd, rr, c); if (rc->rc_size > 0) { ASSERT3P(rc->rc_abd, !=, NULL); zio_nowait(zio_vdev_child_io(zio, NULL, cvd, rc->rc_offset, rc->rc_abd, abd_get_size(rc->rc_abd), zio->io_type, zio->io_priority, 0, vdev_raidz_child_done, rc)); } else { /* * Generate optional write for skip sector to improve * aggregation contiguity. */ ASSERT3P(rc->rc_abd, ==, NULL); zio_nowait(zio_vdev_child_io(zio, NULL, cvd, rc->rc_offset, NULL, 1ULL << ashift, zio->io_type, zio->io_priority, ZIO_FLAG_NODATA | ZIO_FLAG_OPTIONAL, NULL, NULL)); } } } static void vdev_raidz_io_start_read(zio_t *zio, raidz_row_t *rr) { vdev_t *vd = zio->io_vd; /* * 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. */ for (int c = rr->rr_cols - 1; c >= 0; c--) { raidz_col_t *rc = &rr->rr_col[c]; if (rc->rc_size == 0) continue; vdev_t *cvd = vd->vdev_child[rc->rc_devidx]; if (!vdev_readable(cvd)) { if (c >= rr->rr_firstdatacol) rr->rr_missingdata++; else rr->rr_missingparity++; rc->rc_error = SET_ERROR(ENXIO); rc->rc_tried = 1; /* don't even try */ rc->rc_skipped = 1; continue; } if (vdev_dtl_contains(cvd, DTL_MISSING, zio->io_txg, 1)) { if (c >= rr->rr_firstdatacol) rr->rr_missingdata++; else rr->rr_missingparity++; rc->rc_error = SET_ERROR(ESTALE); rc->rc_skipped = 1; continue; } if (c >= rr->rr_firstdatacol || rr->rr_missingdata > 0 || (zio->io_flags & (ZIO_FLAG_SCRUB | ZIO_FLAG_RESILVER))) { zio_nowait(zio_vdev_child_io(zio, NULL, cvd, rc->rc_offset, rc->rc_abd, rc->rc_size, zio->io_type, zio->io_priority, 0, vdev_raidz_child_done, rc)); } } } /* * Start an IO operation on a RAIDZ VDev * * Outline: * - For write operations: * 1. Generate the parity data * 2. Create child zio write operations to each column's vdev, for both * data and parity. * 3. If the column skips any sectors for padding, create optional dummy * write zio children for those areas to improve aggregation continuity. * - For read operations: * 1. Create child zio read operations to each data column's vdev to read * the range of data required for zio. * 2. If this is a scrub or resilver operation, or if any of the data * vdevs have had errors, then create zio read operations to the parity * columns' VDevs as well. */ static void vdev_raidz_io_start(zio_t *zio) { vdev_t *vd = zio->io_vd; vdev_t *tvd = vd->vdev_top; vdev_raidz_t *vdrz = vd->vdev_tsd; raidz_map_t *rm = vdev_raidz_map_alloc(zio, tvd->vdev_ashift, vdrz->vd_logical_width, vdrz->vd_nparity); zio->io_vsd = rm; zio->io_vsd_ops = &vdev_raidz_vsd_ops; /* * Until raidz expansion is implemented all maps for a raidz vdev * contain a single row. */ ASSERT3U(rm->rm_nrows, ==, 1); raidz_row_t *rr = rm->rm_row[0]; if (zio->io_type == ZIO_TYPE_WRITE) { vdev_raidz_io_start_write(zio, rr, tvd->vdev_ashift); } else { ASSERT(zio->io_type == ZIO_TYPE_READ); vdev_raidz_io_start_read(zio, rr); } zio_execute(zio); } /* * Report a checksum error for a child of a RAID-Z device. */ void vdev_raidz_checksum_error(zio_t *zio, raidz_col_t *rc, abd_t *bad_data) { vdev_t *vd = zio->io_vd->vdev_child[rc->rc_devidx]; if (!(zio->io_flags & ZIO_FLAG_SPECULATIVE) && zio->io_priority != ZIO_PRIORITY_REBUILD) { zio_bad_cksum_t zbc; raidz_map_t *rm = zio->io_vsd; zbc.zbc_has_cksum = 0; zbc.zbc_injected = rm->rm_ecksuminjected; (void) zfs_ereport_post_checksum(zio->io_spa, vd, &zio->io_bookmark, zio, rc->rc_offset, rc->rc_size, rc->rc_abd, bad_data, &zbc); mutex_enter(&vd->vdev_stat_lock); vd->vdev_stat.vs_checksum_errors++; mutex_exit(&vd->vdev_stat_lock); } } /* * We keep track of whether or not there were any injected errors, so that * any ereports we generate can note it. */ static int raidz_checksum_verify(zio_t *zio) { zio_bad_cksum_t zbc = {{{0}}}; raidz_map_t *rm = zio->io_vsd; int ret = zio_checksum_error(zio, &zbc); if (ret != 0 && zbc.zbc_injected != 0) rm->rm_ecksuminjected = 1; return (ret); } /* * 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 of such failures. */ static int raidz_parity_verify(zio_t *zio, raidz_row_t *rr) { abd_t *orig[VDEV_RAIDZ_MAXPARITY]; int c, ret = 0; raidz_map_t *rm = zio->io_vsd; raidz_col_t *rc; blkptr_t *bp = zio->io_bp; enum zio_checksum checksum = (bp == NULL ? zio->io_prop.zp_checksum : (BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER : BP_GET_CHECKSUM(bp))); if (checksum == ZIO_CHECKSUM_NOPARITY) return (ret); for (c = 0; c < rr->rr_firstdatacol; c++) { rc = &rr->rr_col[c]; if (!rc->rc_tried || rc->rc_error != 0) continue; orig[c] = rc->rc_abd; ASSERT3U(abd_get_size(rc->rc_abd), ==, rc->rc_size); rc->rc_abd = abd_alloc_linear(rc->rc_size, B_FALSE); } /* * Verify any empty sectors are zero filled to ensure the parity * is calculated correctly even if these non-data sectors are damaged. */ if (rr->rr_nempty && rr->rr_abd_empty != NULL) ret += vdev_draid_map_verify_empty(zio, rr); /* * Regenerates parity even for !tried||rc_error!=0 columns. This * isn't harmful but it does have the side effect of fixing stuff * we didn't realize was necessary (i.e. even if we return 0). */ vdev_raidz_generate_parity_row(rm, rr); for (c = 0; c < rr->rr_firstdatacol; c++) { rc = &rr->rr_col[c]; if (!rc->rc_tried || rc->rc_error != 0) continue; if (abd_cmp(orig[c], rc->rc_abd) != 0) { vdev_raidz_checksum_error(zio, rc, orig[c]); rc->rc_error = SET_ERROR(ECKSUM); ret++; } abd_free(orig[c]); } return (ret); } static int vdev_raidz_worst_error(raidz_row_t *rr) { int error = 0; for (int c = 0; c < rr->rr_cols; c++) error = zio_worst_error(error, rr->rr_col[c].rc_error); return (error); } static void vdev_raidz_io_done_verified(zio_t *zio, raidz_row_t *rr) { int unexpected_errors = 0; int parity_errors = 0; int parity_untried = 0; int data_errors = 0; ASSERT3U(zio->io_type, ==, ZIO_TYPE_READ); for (int c = 0; c < rr->rr_cols; c++) { raidz_col_t *rc = &rr->rr_col[c]; if (rc->rc_error) { if (c < rr->rr_firstdatacol) parity_errors++; else data_errors++; if (!rc->rc_skipped) unexpected_errors++; } else if (c < rr->rr_firstdatacol && !rc->rc_tried) { parity_untried++; } if (rc->rc_force_repair) unexpected_errors++; } /* * If we read more parity disks than were used for * reconstruction, confirm that the other parity disks produced * correct data. * * Note that we also regenerate parity when resilvering so we * can write it out to failed devices later. */ if (parity_errors + parity_untried < rr->rr_firstdatacol - data_errors || (zio->io_flags & ZIO_FLAG_RESILVER)) { int n = raidz_parity_verify(zio, rr); unexpected_errors += n; } if (zio->io_error == 0 && spa_writeable(zio->io_spa) && (unexpected_errors > 0 || (zio->io_flags & ZIO_FLAG_RESILVER))) { /* * Use the good data we have in hand to repair damaged children. */ for (int c = 0; c < rr->rr_cols; c++) { raidz_col_t *rc = &rr->rr_col[c]; vdev_t *vd = zio->io_vd; vdev_t *cvd = vd->vdev_child[rc->rc_devidx]; if (!rc->rc_allow_repair) { continue; } else if (!rc->rc_force_repair && (rc->rc_error == 0 || rc->rc_size == 0)) { continue; } zio_nowait(zio_vdev_child_io(zio, NULL, cvd, rc->rc_offset, rc->rc_abd, rc->rc_size, ZIO_TYPE_WRITE, zio->io_priority == ZIO_PRIORITY_REBUILD ? ZIO_PRIORITY_REBUILD : ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_IO_REPAIR | (unexpected_errors ? ZIO_FLAG_SELF_HEAL : 0), NULL, NULL)); } } } static void raidz_restore_orig_data(raidz_map_t *rm) { for (int i = 0; i < rm->rm_nrows; i++) { raidz_row_t *rr = rm->rm_row[i]; for (int c = 0; c < rr->rr_cols; c++) { raidz_col_t *rc = &rr->rr_col[c]; if (rc->rc_need_orig_restore) { abd_copy(rc->rc_abd, rc->rc_orig_data, rc->rc_size); rc->rc_need_orig_restore = B_FALSE; } } } } /* * returns EINVAL if reconstruction of the block will not be possible * returns ECKSUM if this specific reconstruction failed * returns 0 on successful reconstruction */ static int raidz_reconstruct(zio_t *zio, int *ltgts, int ntgts, int nparity) { raidz_map_t *rm = zio->io_vsd; /* Reconstruct each row */ for (int r = 0; r < rm->rm_nrows; r++) { raidz_row_t *rr = rm->rm_row[r]; int my_tgts[VDEV_RAIDZ_MAXPARITY]; /* value is child id */ int t = 0; int dead = 0; int dead_data = 0; for (int c = 0; c < rr->rr_cols; c++) { raidz_col_t *rc = &rr->rr_col[c]; ASSERT0(rc->rc_need_orig_restore); if (rc->rc_error != 0) { dead++; if (c >= nparity) dead_data++; continue; } if (rc->rc_size == 0) continue; for (int lt = 0; lt < ntgts; lt++) { if (rc->rc_devidx == ltgts[lt]) { if (rc->rc_orig_data == NULL) { rc->rc_orig_data = abd_alloc_linear( rc->rc_size, B_TRUE); abd_copy(rc->rc_orig_data, rc->rc_abd, rc->rc_size); } rc->rc_need_orig_restore = B_TRUE; dead++; if (c >= nparity) dead_data++; my_tgts[t++] = c; break; } } } if (dead > nparity) { /* reconstruction not possible */ raidz_restore_orig_data(rm); return (EINVAL); } if (dead_data > 0) vdev_raidz_reconstruct_row(rm, rr, my_tgts, t); } /* Check for success */ if (raidz_checksum_verify(zio) == 0) { /* Reconstruction succeeded - report errors */ for (int i = 0; i < rm->rm_nrows; i++) { raidz_row_t *rr = rm->rm_row[i]; for (int c = 0; c < rr->rr_cols; c++) { raidz_col_t *rc = &rr->rr_col[c]; if (rc->rc_need_orig_restore) { /* * Note: if this is a parity column, * we don't really know if it's wrong. * We need to let * vdev_raidz_io_done_verified() check * it, and if we set rc_error, it will * think that it is a "known" error * that doesn't need to be checked * or corrected. */ if (rc->rc_error == 0 && c >= rr->rr_firstdatacol) { vdev_raidz_checksum_error(zio, rc, rc->rc_orig_data); rc->rc_error = SET_ERROR(ECKSUM); } rc->rc_need_orig_restore = B_FALSE; } } vdev_raidz_io_done_verified(zio, rr); } zio_checksum_verified(zio); return (0); } /* Reconstruction failed - restore original data */ raidz_restore_orig_data(rm); return (ECKSUM); } /* * Iterate over all combinations of N bad vdevs and attempt a reconstruction. * Note that the algorithm below is non-optimal because it doesn't take into * account how reconstruction is actually performed. For example, with * triple-parity RAID-Z the reconstruction procedure is the same if column 4 * is targeted as invalid as if columns 1 and 4 are targeted since in both * cases we'd only use parity information in column 0. * * The order that we find the various possible combinations of failed * disks is dictated by these rules: * - Examine each "slot" (the "i" in tgts[i]) * - Try to increment this slot (tgts[i] = tgts[i] + 1) * - if we can't increment because it runs into the next slot, * reset our slot to the minimum, and examine the next slot * * For example, with a 6-wide RAIDZ3, and no known errors (so we have to choose * 3 columns to reconstruct), we will generate the following sequence: * * STATE ACTION * 0 1 2 special case: skip since these are all parity * 0 1 3 first slot: reset to 0; middle slot: increment to 2 * 0 2 3 first slot: increment to 1 * 1 2 3 first: reset to 0; middle: reset to 1; last: increment to 4 * 0 1 4 first: reset to 0; middle: increment to 2 * 0 2 4 first: increment to 1 * 1 2 4 first: reset to 0; middle: increment to 3 * 0 3 4 first: increment to 1 * 1 3 4 first: increment to 2 * 2 3 4 first: reset to 0; middle: reset to 1; last: increment to 5 * 0 1 5 first: reset to 0; middle: increment to 2 * 0 2 5 first: increment to 1 * 1 2 5 first: reset to 0; middle: increment to 3 * 0 3 5 first: increment to 1 * 1 3 5 first: increment to 2 * 2 3 5 first: reset to 0; middle: increment to 4 * 0 4 5 first: increment to 1 * 1 4 5 first: increment to 2 * 2 4 5 first: increment to 3 * 3 4 5 done * * This strategy works for dRAID but is less efficient when there are a large * number of child vdevs and therefore permutations to check. Furthermore, * since the raidz_map_t rows likely do not overlap reconstruction would be * possible as long as there are no more than nparity data errors per row. * These additional permutations are not currently checked but could be as * a future improvement. */ static int vdev_raidz_combrec(zio_t *zio) { int nparity = vdev_get_nparity(zio->io_vd); raidz_map_t *rm = zio->io_vsd; /* Check if there's enough data to attempt reconstrution. */ for (int i = 0; i < rm->rm_nrows; i++) { raidz_row_t *rr = rm->rm_row[i]; int total_errors = 0; for (int c = 0; c < rr->rr_cols; c++) { if (rr->rr_col[c].rc_error) total_errors++; } if (total_errors > nparity) return (vdev_raidz_worst_error(rr)); } for (int num_failures = 1; num_failures <= nparity; num_failures++) { int tstore[VDEV_RAIDZ_MAXPARITY + 2]; int *ltgts = &tstore[1]; /* value is logical child ID */ /* Determine number of logical children, n */ int n = zio->io_vd->vdev_children; ASSERT3U(num_failures, <=, nparity); ASSERT3U(num_failures, <=, VDEV_RAIDZ_MAXPARITY); /* Handle corner cases in combrec logic */ ltgts[-1] = -1; for (int i = 0; i < num_failures; i++) { ltgts[i] = i; } ltgts[num_failures] = n; for (;;) { int err = raidz_reconstruct(zio, ltgts, num_failures, nparity); if (err == EINVAL) { /* * Reconstruction not possible with this # * failures; try more failures. */ break; } else if (err == 0) return (0); /* Compute next targets to try */ for (int t = 0; ; t++) { ASSERT3U(t, <, num_failures); ltgts[t]++; if (ltgts[t] == n) { /* try more failures */ ASSERT3U(t, ==, num_failures - 1); break; } ASSERT3U(ltgts[t], <, n); ASSERT3U(ltgts[t], <=, ltgts[t + 1]); /* * If that spot is available, we're done here. * Try the next combination. */ if (ltgts[t] != ltgts[t + 1]) break; /* * Otherwise, reset this tgt to the minimum, * and move on to the next tgt. */ ltgts[t] = ltgts[t - 1] + 1; ASSERT3U(ltgts[t], ==, t); } /* Increase the number of failures and keep trying. */ if (ltgts[num_failures - 1] == n) break; } } return (ECKSUM); } void vdev_raidz_reconstruct(raidz_map_t *rm, const int *t, int nt) { for (uint64_t row = 0; row < rm->rm_nrows; row++) { raidz_row_t *rr = rm->rm_row[row]; vdev_raidz_reconstruct_row(rm, rr, t, nt); } } /* * Complete a write IO operation on a RAIDZ VDev * * Outline: * 1. Check for errors on the child IOs. * 2. Return, setting an error code if too few child VDevs were written * to reconstruct the data later. Note that partial writes are * considered successful if they can be reconstructed at all. */ static void vdev_raidz_io_done_write_impl(zio_t *zio, raidz_row_t *rr) { int total_errors = 0; ASSERT3U(rr->rr_missingparity, <=, rr->rr_firstdatacol); ASSERT3U(rr->rr_missingdata, <=, rr->rr_cols - rr->rr_firstdatacol); ASSERT3U(zio->io_type, ==, ZIO_TYPE_WRITE); for (int c = 0; c < rr->rr_cols; c++) { raidz_col_t *rc = &rr->rr_col[c]; if (rc->rc_error) { ASSERT(rc->rc_error != ECKSUM); /* child has no bp */ total_errors++; } } /* * 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. */ if (total_errors > rr->rr_firstdatacol) { zio->io_error = zio_worst_error(zio->io_error, vdev_raidz_worst_error(rr)); } } static void vdev_raidz_io_done_reconstruct_known_missing(zio_t *zio, raidz_map_t *rm, raidz_row_t *rr) { int parity_errors = 0; int parity_untried = 0; int data_errors = 0; int total_errors = 0; ASSERT3U(rr->rr_missingparity, <=, rr->rr_firstdatacol); ASSERT3U(rr->rr_missingdata, <=, rr->rr_cols - rr->rr_firstdatacol); ASSERT3U(zio->io_type, ==, ZIO_TYPE_READ); for (int c = 0; c < rr->rr_cols; c++) { raidz_col_t *rc = &rr->rr_col[c]; /* * If scrubbing and a replacing/sparing child vdev determined * that not all of its children have an identical copy of the * data, then clear the error so the column is treated like * any other read and force a repair to correct the damage. */ if (rc->rc_error == ECKSUM) { ASSERT(zio->io_flags & ZIO_FLAG_SCRUB); vdev_raidz_checksum_error(zio, rc, rc->rc_abd); rc->rc_force_repair = 1; rc->rc_error = 0; } if (rc->rc_error) { if (c < rr->rr_firstdatacol) parity_errors++; else data_errors++; total_errors++; } else if (c < rr->rr_firstdatacol && !rc->rc_tried) { parity_untried++; } } /* * If there were data errors and the number of errors we saw was * correctable -- less than or equal to the number of parity disks read * -- reconstruct based on the missing data. */ if (data_errors != 0 && total_errors <= rr->rr_firstdatacol - parity_untried) { /* * 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 < rr->rr_firstdatacol); /* * Identify the data columns that reported an error. */ int n = 0; int tgts[VDEV_RAIDZ_MAXPARITY]; for (int c = rr->rr_firstdatacol; c < rr->rr_cols; c++) { raidz_col_t *rc = &rr->rr_col[c]; if (rc->rc_error != 0) { ASSERT(n < VDEV_RAIDZ_MAXPARITY); tgts[n++] = c; } } ASSERT(rr->rr_firstdatacol >= n); vdev_raidz_reconstruct_row(rm, rr, tgts, n); } } /* * Return the number of reads issued. */ static int vdev_raidz_read_all(zio_t *zio, raidz_row_t *rr) { vdev_t *vd = zio->io_vd; int nread = 0; rr->rr_missingdata = 0; rr->rr_missingparity = 0; /* * If this rows contains empty sectors which are not required * for a normal read then allocate an ABD for them now so they * may be read, verified, and any needed repairs performed. */ if (rr->rr_nempty && rr->rr_abd_empty == NULL) vdev_draid_map_alloc_empty(zio, rr); for (int c = 0; c < rr->rr_cols; c++) { raidz_col_t *rc = &rr->rr_col[c]; if (rc->rc_tried || rc->rc_size == 0) continue; zio_nowait(zio_vdev_child_io(zio, NULL, vd->vdev_child[rc->rc_devidx], rc->rc_offset, rc->rc_abd, rc->rc_size, zio->io_type, zio->io_priority, 0, vdev_raidz_child_done, rc)); nread++; } return (nread); } /* * We're here because either there were too many errors to even attempt * reconstruction (total_errors == rm_first_datacol), or vdev_*_combrec() * failed. In either case, there is enough bad data to prevent reconstruction. * Start checksum ereports for all children which haven't failed. */ static void vdev_raidz_io_done_unrecoverable(zio_t *zio) { raidz_map_t *rm = zio->io_vsd; for (int i = 0; i < rm->rm_nrows; i++) { raidz_row_t *rr = rm->rm_row[i]; for (int c = 0; c < rr->rr_cols; c++) { raidz_col_t *rc = &rr->rr_col[c]; vdev_t *cvd = zio->io_vd->vdev_child[rc->rc_devidx]; if (rc->rc_error != 0) continue; zio_bad_cksum_t zbc; zbc.zbc_has_cksum = 0; zbc.zbc_injected = rm->rm_ecksuminjected; (void) zfs_ereport_start_checksum(zio->io_spa, cvd, &zio->io_bookmark, zio, rc->rc_offset, rc->rc_size, &zbc); mutex_enter(&cvd->vdev_stat_lock); cvd->vdev_stat.vs_checksum_errors++; mutex_exit(&cvd->vdev_stat_lock); } } } void vdev_raidz_io_done(zio_t *zio) { raidz_map_t *rm = zio->io_vsd; if (zio->io_type == ZIO_TYPE_WRITE) { for (int i = 0; i < rm->rm_nrows; i++) { vdev_raidz_io_done_write_impl(zio, rm->rm_row[i]); } } else { for (int i = 0; i < rm->rm_nrows; i++) { raidz_row_t *rr = rm->rm_row[i]; vdev_raidz_io_done_reconstruct_known_missing(zio, rm, rr); } if (raidz_checksum_verify(zio) == 0) { for (int i = 0; i < rm->rm_nrows; i++) { raidz_row_t *rr = rm->rm_row[i]; vdev_raidz_io_done_verified(zio, rr); } zio_checksum_verified(zio); } else { /* * A sequential resilver has no checksum which makes * combinatoral reconstruction impossible. This code * path is unreachable since raidz_checksum_verify() * has no checksum to verify and must succeed. */ ASSERT3U(zio->io_priority, !=, ZIO_PRIORITY_REBUILD); /* * 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. */ int nread = 0; for (int i = 0; i < rm->rm_nrows; i++) { nread += vdev_raidz_read_all(zio, rm->rm_row[i]); } if (nread != 0) { /* * Normally our stage is VDEV_IO_DONE, but if * we've already called redone(), it will have * changed to VDEV_IO_START, in which case we * don't want to call redone() again. */ if (zio->io_stage != ZIO_STAGE_VDEV_IO_START) zio_vdev_io_redone(zio); return; } zio->io_error = vdev_raidz_combrec(zio); if (zio->io_error == ECKSUM && !(zio->io_flags & ZIO_FLAG_SPECULATIVE)) { vdev_raidz_io_done_unrecoverable(zio); } } } } static void vdev_raidz_state_change(vdev_t *vd, int faulted, int degraded) { vdev_raidz_t *vdrz = vd->vdev_tsd; if (faulted > vdrz->vd_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); } /* * Determine if any portion of the provided block resides on a child vdev * with a dirty DTL and therefore needs to be resilvered. The function * assumes that at least one DTL is dirty which implies that full stripe * width blocks must be resilvered. */ static boolean_t vdev_raidz_need_resilver(vdev_t *vd, const dva_t *dva, size_t psize, uint64_t phys_birth) { vdev_raidz_t *vdrz = vd->vdev_tsd; uint64_t dcols = vd->vdev_children; uint64_t nparity = vdrz->vd_nparity; uint64_t ashift = vd->vdev_top->vdev_ashift; /* The starting RAIDZ (parent) vdev sector of the block. */ uint64_t b = DVA_GET_OFFSET(dva) >> ashift; /* The zio's size in units of the vdev's minimum sector size. */ uint64_t s = ((psize - 1) >> ashift) + 1; /* The first column for this stripe. */ uint64_t f = b % dcols; /* Unreachable by sequential resilver. */ ASSERT3U(phys_birth, !=, TXG_UNKNOWN); if (!vdev_dtl_contains(vd, DTL_PARTIAL, phys_birth, 1)) return (B_FALSE); if (s + nparity >= dcols) return (B_TRUE); for (uint64_t c = 0; c < s + nparity; c++) { uint64_t devidx = (f + c) % dcols; vdev_t *cvd = vd->vdev_child[devidx]; /* * dsl_scan_need_resilver() already checked vd with * vdev_dtl_contains(). So here just check cvd with * vdev_dtl_empty(), cheaper and a good approximation. */ if (!vdev_dtl_empty(cvd, DTL_PARTIAL)) return (B_TRUE); } return (B_FALSE); } static void vdev_raidz_xlate(vdev_t *cvd, const range_seg64_t *logical_rs, range_seg64_t *physical_rs, range_seg64_t *remain_rs) { (void) remain_rs; vdev_t *raidvd = cvd->vdev_parent; ASSERT(raidvd->vdev_ops == &vdev_raidz_ops); uint64_t width = raidvd->vdev_children; uint64_t tgt_col = cvd->vdev_id; uint64_t ashift = raidvd->vdev_top->vdev_ashift; /* make sure the offsets are block-aligned */ ASSERT0(logical_rs->rs_start % (1 << ashift)); ASSERT0(logical_rs->rs_end % (1 << ashift)); uint64_t b_start = logical_rs->rs_start >> ashift; uint64_t b_end = logical_rs->rs_end >> ashift; uint64_t start_row = 0; if (b_start > tgt_col) /* avoid underflow */ start_row = ((b_start - tgt_col - 1) / width) + 1; uint64_t end_row = 0; if (b_end > tgt_col) end_row = ((b_end - tgt_col - 1) / width) + 1; physical_rs->rs_start = start_row << ashift; physical_rs->rs_end = end_row << ashift; ASSERT3U(physical_rs->rs_start, <=, logical_rs->rs_start); ASSERT3U(physical_rs->rs_end - physical_rs->rs_start, <=, logical_rs->rs_end - logical_rs->rs_start); } /* * Initialize private RAIDZ specific fields from the nvlist. */ static int vdev_raidz_init(spa_t *spa, nvlist_t *nv, void **tsd) { vdev_raidz_t *vdrz; uint64_t nparity; uint_t children; nvlist_t **child; int error = nvlist_lookup_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN, &child, &children); if (error != 0) return (SET_ERROR(EINVAL)); if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_NPARITY, &nparity) == 0) { if (nparity == 0 || nparity > VDEV_RAIDZ_MAXPARITY) return (SET_ERROR(EINVAL)); /* * Previous versions could only support 1 or 2 parity * device. */ if (nparity > 1 && spa_version(spa) < SPA_VERSION_RAIDZ2) return (SET_ERROR(EINVAL)); else if (nparity > 2 && spa_version(spa) < SPA_VERSION_RAIDZ3) return (SET_ERROR(EINVAL)); } else { /* * We require the parity to be specified for SPAs that * support multiple parity levels. */ if (spa_version(spa) >= SPA_VERSION_RAIDZ2) return (SET_ERROR(EINVAL)); /* * Otherwise, we default to 1 parity device for RAID-Z. */ nparity = 1; } vdrz = kmem_zalloc(sizeof (*vdrz), KM_SLEEP); vdrz->vd_logical_width = children; vdrz->vd_nparity = nparity; *tsd = vdrz; return (0); } static void vdev_raidz_fini(vdev_t *vd) { kmem_free(vd->vdev_tsd, sizeof (vdev_raidz_t)); } /* * Add RAIDZ specific fields to the config nvlist. */ static void vdev_raidz_config_generate(vdev_t *vd, nvlist_t *nv) { ASSERT3P(vd->vdev_ops, ==, &vdev_raidz_ops); vdev_raidz_t *vdrz = vd->vdev_tsd; /* * Make sure someone hasn't managed to sneak a fancy new vdev * into a crufty old storage pool. */ ASSERT(vdrz->vd_nparity == 1 || (vdrz->vd_nparity <= 2 && spa_version(vd->vdev_spa) >= SPA_VERSION_RAIDZ2) || (vdrz->vd_nparity <= 3 && spa_version(vd->vdev_spa) >= SPA_VERSION_RAIDZ3)); /* * Note that we'll add these even on storage pools where they * aren't strictly required -- older software will just ignore * it. */ fnvlist_add_uint64(nv, ZPOOL_CONFIG_NPARITY, vdrz->vd_nparity); } static uint64_t vdev_raidz_nparity(vdev_t *vd) { vdev_raidz_t *vdrz = vd->vdev_tsd; return (vdrz->vd_nparity); } static uint64_t vdev_raidz_ndisks(vdev_t *vd) { return (vd->vdev_children); } vdev_ops_t vdev_raidz_ops = { .vdev_op_init = vdev_raidz_init, .vdev_op_fini = vdev_raidz_fini, .vdev_op_open = vdev_raidz_open, .vdev_op_close = vdev_raidz_close, .vdev_op_asize = vdev_raidz_asize, .vdev_op_min_asize = vdev_raidz_min_asize, .vdev_op_min_alloc = NULL, .vdev_op_io_start = vdev_raidz_io_start, .vdev_op_io_done = vdev_raidz_io_done, .vdev_op_state_change = vdev_raidz_state_change, .vdev_op_need_resilver = vdev_raidz_need_resilver, .vdev_op_hold = NULL, .vdev_op_rele = NULL, .vdev_op_remap = NULL, .vdev_op_xlate = vdev_raidz_xlate, .vdev_op_rebuild_asize = NULL, .vdev_op_metaslab_init = NULL, .vdev_op_config_generate = vdev_raidz_config_generate, .vdev_op_nparity = vdev_raidz_nparity, .vdev_op_ndisks = vdev_raidz_ndisks, .vdev_op_type = VDEV_TYPE_RAIDZ, /* name of this vdev type */ .vdev_op_leaf = B_FALSE /* not a leaf vdev */ };