/* * 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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2012, 2017 by Delphix. All rights reserved. * Copyright (c) 2013, Joyent, Inc. All rights reserved. * Copyright (c) 2014 Integros [integros.com] */ #include #include #include #include #include #include #include #include #include #include #include #ifdef ZFS_DEBUG #include /* vdev_xlate testing */ #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 trival * 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. */ 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 */ abd_t *rc_abd; /* I/O data */ void *rc_gdata; /* used to store the "good" version */ 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; /* Regular column count */ uint64_t rm_scols; /* Count including skipped columns */ 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 */ uint64_t rm_nskip; /* Skipped sectors for padding */ uint64_t rm_skipstart; /* Column index of padding start */ abd_t *rm_abd_copy; /* rm_asize-buffer of copied data */ uintptr_t rm_reports; /* # of referencing checksum reports */ uint8_t rm_freed; /* map no longer has referencing ZIO */ uint8_t rm_ecksuminjected; /* checksum error was injected */ 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_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) & 0x1d1d1d1d1d1d1d1d); \ } #define VDEV_RAIDZ_64MUL_4(x, mask) \ { \ VDEV_RAIDZ_64MUL_2((x), mask); \ VDEV_RAIDZ_64MUL_2((x), mask); \ } #define VDEV_LABEL_OFFSET(x) (x + VDEV_LABEL_START_SIZE) /* * Force reconstruction to use the general purpose method. */ int vdev_raidz_default_to_general; /* Powers of 2 in the Galois field defined 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 }; /* Logs of 2 in the Galois field defined above. */ 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, }; static void vdev_raidz_generate_parity(raidz_map_t *rm); /* * 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(raidz_map_t *rm) { int c; for (c = 0; c < rm->rm_firstdatacol; c++) { abd_free(rm->rm_col[c].rc_abd); if (rm->rm_col[c].rc_gdata != NULL) abd_free(rm->rm_col[c].rc_gdata); } for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) abd_put(rm->rm_col[c].rc_abd); if (rm->rm_abd_copy != NULL) abd_free(rm->rm_abd_copy); kmem_free(rm, offsetof(raidz_map_t, rm_col[rm->rm_scols])); } static void vdev_raidz_map_free_vsd(zio_t *zio) { raidz_map_t *rm = zio->io_vsd; ASSERT0(rm->rm_freed); rm->rm_freed = 1; if (rm->rm_reports == 0) vdev_raidz_map_free(rm); } /*ARGSUSED*/ static void vdev_raidz_cksum_free(void *arg, size_t ignored) { raidz_map_t *rm = arg; ASSERT3U(rm->rm_reports, >, 0); if (--rm->rm_reports == 0 && rm->rm_freed != 0) vdev_raidz_map_free(rm); } static void vdev_raidz_cksum_finish(zio_cksum_report_t *zcr, const abd_t *good_data) { raidz_map_t *rm = zcr->zcr_cbdata; size_t c = zcr->zcr_cbinfo; size_t x, offset; const abd_t *good = NULL; const abd_t *bad = rm->rm_col[c].rc_abd; if (good_data == NULL) { zfs_ereport_finish_checksum(zcr, NULL, NULL, B_FALSE); return; } if (c < rm->rm_firstdatacol) { /* * The first time through, calculate the parity blocks for * the good data (this relies on the fact that the good * data never changes for a given logical ZIO) */ if (rm->rm_col[0].rc_gdata == NULL) { abd_t *bad_parity[VDEV_RAIDZ_MAXPARITY]; /* * Set up the rm_col[]s to generate the parity for * good_data, first saving the parity bufs and * replacing them with buffers to hold the result. */ for (x = 0; x < rm->rm_firstdatacol; x++) { bad_parity[x] = rm->rm_col[x].rc_abd; rm->rm_col[x].rc_abd = rm->rm_col[x].rc_gdata = abd_alloc_sametype(rm->rm_col[x].rc_abd, rm->rm_col[x].rc_size); } /* fill in the data columns from good_data */ offset = 0; for (; x < rm->rm_cols; x++) { abd_put(rm->rm_col[x].rc_abd); rm->rm_col[x].rc_abd = abd_get_offset_size((abd_t *)good_data, offset, rm->rm_col[x].rc_size); offset += rm->rm_col[x].rc_size; } /* * Construct the parity from the good data. */ vdev_raidz_generate_parity(rm); /* restore everything back to its original state */ for (x = 0; x < rm->rm_firstdatacol; x++) rm->rm_col[x].rc_abd = bad_parity[x]; offset = 0; for (x = rm->rm_firstdatacol; x < rm->rm_cols; x++) { abd_put(rm->rm_col[x].rc_abd); rm->rm_col[x].rc_abd = abd_get_offset_size( rm->rm_abd_copy, offset, rm->rm_col[x].rc_size); offset += rm->rm_col[x].rc_size; } } ASSERT3P(rm->rm_col[c].rc_gdata, !=, NULL); good = abd_get_offset_size(rm->rm_col[c].rc_gdata, 0, rm->rm_col[c].rc_size); } else { /* adjust good_data to point at the start of our column */ offset = 0; for (x = rm->rm_firstdatacol; x < c; x++) offset += rm->rm_col[x].rc_size; good = abd_get_offset_size((abd_t *)good_data, offset, rm->rm_col[c].rc_size); } /* we drop the ereport if it ends up that the data was good */ zfs_ereport_finish_checksum(zcr, good, bad, B_TRUE); abd_put((abd_t *)good); } /* * Invoked indirectly by zfs_ereport_start_checksum(), called * below when our read operation fails completely. The main point * is to keep a copy of everything we read from disk, so that at * vdev_raidz_cksum_finish() time we can compare it with the good data. */ static void vdev_raidz_cksum_report(zio_t *zio, zio_cksum_report_t *zcr, void *arg) { size_t c = (size_t)(uintptr_t)arg; size_t offset; raidz_map_t *rm = zio->io_vsd; size_t size; /* set up the report and bump the refcount */ zcr->zcr_cbdata = rm; zcr->zcr_cbinfo = c; zcr->zcr_finish = vdev_raidz_cksum_finish; zcr->zcr_free = vdev_raidz_cksum_free; rm->rm_reports++; ASSERT3U(rm->rm_reports, >, 0); if (rm->rm_abd_copy != NULL) return; /* * It's the first time we're called for this raidz_map_t, so we need * to copy the data aside; there's no guarantee that our zio's buffer * won't be re-used for something else. * * Our parity data is already in separate buffers, so there's no need * to copy them. */ size = 0; for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) size += rm->rm_col[c].rc_size; rm->rm_abd_copy = abd_alloc_for_io(size, B_FALSE); for (offset = 0, c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { raidz_col_t *col = &rm->rm_col[c]; abd_t *tmp = abd_get_offset_size(rm->rm_abd_copy, offset, col->rc_size); ASSERT3S(tmp->abd_size, >=, col->rc_size); ASSERT3S(col->rc_abd->abd_size, >=, col->rc_size); abd_copy_off(tmp, col->rc_abd, 0, 0, col->rc_size); abd_put(col->rc_abd); col->rc_abd = tmp; offset += col->rc_size; } ASSERT3U(offset, ==, size); } static const zio_vsd_ops_t vdev_raidz_vsd_ops = { vdev_raidz_map_free_vsd, vdev_raidz_cksum_report }; /* * Divides the IO evenly across all child vdevs; usually, dcols is * the number of children in the target vdev. */ static raidz_map_t * vdev_raidz_map_alloc(abd_t *abd, uint64_t size, uint64_t offset, uint64_t unit_shift, uint64_t dcols, uint64_t nparity) { raidz_map_t *rm; /* The starting RAIDZ (parent) vdev sector of the block. */ uint64_t b = offset >> unit_shift; /* The zio's size in units of the vdev's minimum sector size. */ uint64_t s = size >> unit_shift; /* The first column for this stripe. */ uint64_t f = b % dcols; /* The starting byte offset on each child vdev. */ uint64_t o = (b / dcols) << unit_shift; uint64_t q, r, c, bc, col, acols, scols, coff, devidx, asize, tot; uint64_t off = 0; /* * "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); rm = kmem_alloc(offsetof(raidz_map_t, rm_col[scols]), KM_SLEEP); rm->rm_cols = acols; rm->rm_scols = scols; rm->rm_bigcols = bc; rm->rm_skipstart = bc; rm->rm_missingdata = 0; rm->rm_missingparity = 0; rm->rm_firstdatacol = nparity; rm->rm_abd_copy = NULL; rm->rm_reports = 0; rm->rm_freed = 0; rm->rm_ecksuminjected = 0; asize = 0; for (c = 0; c < scols; 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_abd = NULL; rm->rm_col[c].rc_gdata = NULL; rm->rm_col[c].rc_error = 0; rm->rm_col[c].rc_tried = 0; rm->rm_col[c].rc_skipped = 0; if (c >= acols) rm->rm_col[c].rc_size = 0; else if (c < bc) rm->rm_col[c].rc_size = (q + 1) << unit_shift; else rm->rm_col[c].rc_size = q << unit_shift; asize += rm->rm_col[c].rc_size; } ASSERT3U(asize, ==, tot << unit_shift); rm->rm_asize = roundup(asize, (nparity + 1) << unit_shift); rm->rm_nskip = roundup(tot, nparity + 1) - tot; ASSERT3U(rm->rm_asize - asize, ==, rm->rm_nskip << unit_shift); ASSERT3U(rm->rm_nskip, <=, nparity); for (c = 0; c < rm->rm_firstdatacol; c++) rm->rm_col[c].rc_abd = abd_alloc_linear(rm->rm_col[c].rc_size, B_FALSE); rm->rm_col[c].rc_abd = abd_get_offset_size(abd, 0, rm->rm_col[c].rc_size); off = rm->rm_col[c].rc_size; for (c = c + 1; c < acols; c++) { rm->rm_col[c].rc_abd = abd_get_offset_size(abd, off, rm->rm_col[c].rc_size); off += rm->rm_col[c].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. * * 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(rm->rm_cols >= 2); ASSERT(rm->rm_col[0].rc_size == rm->rm_col[1].rc_size); if (rm->rm_firstdatacol == 1 && (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; if (rm->rm_skipstart == 0) rm->rm_skipstart = 1; } 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_map_t *rm) { uint64_t *p; int c; abd_t *src; for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { src = rm->rm_col[c].rc_abd; p = abd_to_buf(rm->rm_col[VDEV_RAIDZ_P].rc_abd); if (c == rm->rm_firstdatacol) { ASSERT3U(src->abd_size, >=, rm->rm_col[c].rc_size); abd_copy_to_buf_off(p, src, 0, rm->rm_col[c].rc_size); } else { struct pqr_struct pqr = { p, NULL, NULL }; (void) abd_iterate_func(src, 0, rm->rm_col[c].rc_size, vdev_raidz_p_func, &pqr); } } } static void vdev_raidz_generate_parity_pq(raidz_map_t *rm) { uint64_t *p, *q, pcnt, ccnt, mask, i; int c; abd_t *src; pcnt = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (p[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_abd; p = abd_to_buf(rm->rm_col[VDEV_RAIDZ_P].rc_abd); q = abd_to_buf(rm->rm_col[VDEV_RAIDZ_Q].rc_abd); ccnt = rm->rm_col[c].rc_size / sizeof (p[0]); if (c == rm->rm_firstdatacol) { ASSERT(ccnt == pcnt || ccnt == 0); abd_copy_to_buf_off(p, src, 0, rm->rm_col[c].rc_size); (void) memcpy(q, p, rm->rm_col[c].rc_size); for (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, rm->rm_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. */ for (i = ccnt; i < pcnt; i++) { VDEV_RAIDZ_64MUL_2(q[i], mask); } } } } static void vdev_raidz_generate_parity_pqr(raidz_map_t *rm) { uint64_t *p, *q, *r, pcnt, ccnt, mask, i; int c; abd_t *src; pcnt = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (p[0]); ASSERT(rm->rm_col[VDEV_RAIDZ_P].rc_size == rm->rm_col[VDEV_RAIDZ_Q].rc_size); ASSERT(rm->rm_col[VDEV_RAIDZ_P].rc_size == rm->rm_col[VDEV_RAIDZ_R].rc_size); for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { src = rm->rm_col[c].rc_abd; p = abd_to_buf(rm->rm_col[VDEV_RAIDZ_P].rc_abd); q = abd_to_buf(rm->rm_col[VDEV_RAIDZ_Q].rc_abd); r = abd_to_buf(rm->rm_col[VDEV_RAIDZ_R].rc_abd); ccnt = rm->rm_col[c].rc_size / sizeof (p[0]); if (c == rm->rm_firstdatacol) { ASSERT3S(src->abd_size, >=, rm->rm_col[c].rc_size); ASSERT(ccnt == pcnt || ccnt == 0); abd_copy_to_buf_off(p, src, 0, rm->rm_col[c].rc_size); (void) memcpy(q, p, rm->rm_col[c].rc_size); (void) memcpy(r, p, rm->rm_col[c].rc_size); for (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, rm->rm_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. */ for (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. */ static void vdev_raidz_generate_parity(raidz_map_t *rm) { switch (rm->rm_firstdatacol) { case 1: vdev_raidz_generate_parity_p(rm); break; case 2: vdev_raidz_generate_parity_pq(rm); break; case 3: vdev_raidz_generate_parity_pqr(rm); break; default: cmn_err(CE_PANIC, "invalid RAID-Z configuration"); } } /* ARGSUSED */ static int vdev_raidz_reconst_p_func(void *dbuf, void *sbuf, size_t size, 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); } /* ARGSUSED */ static int vdev_raidz_reconst_q_pre_func(void *dbuf, void *sbuf, size_t size, 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); } /* ARGSUSED */ static int vdev_raidz_reconst_q_pre_tail_func(void *buf, size_t size, 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++) { *dst ^= *rq->q; int j; uint8_t *b; 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 int vdev_raidz_reconstruct_p(raidz_map_t *rm, int *tgts, int ntgts) { int x = tgts[0]; int c; abd_t *dst, *src; ASSERT(ntgts == 1); ASSERT(x >= rm->rm_firstdatacol); ASSERT(x < rm->rm_cols); ASSERT(rm->rm_col[x].rc_size <= rm->rm_col[VDEV_RAIDZ_P].rc_size); ASSERT(rm->rm_col[x].rc_size > 0); src = rm->rm_col[VDEV_RAIDZ_P].rc_abd; dst = rm->rm_col[x].rc_abd; ASSERT3S(dst->abd_size, >=, rm->rm_col[x].rc_size); ASSERT3S(src->abd_size, >=, rm->rm_col[x].rc_size); abd_copy_off(dst, src, 0, 0, rm->rm_col[x].rc_size); for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { uint64_t size = MIN(rm->rm_col[x].rc_size, rm->rm_col[c].rc_size); src = rm->rm_col[c].rc_abd; dst = rm->rm_col[x].rc_abd; if (c == x) continue; (void) abd_iterate_func2(dst, src, 0, 0, size, vdev_raidz_reconst_p_func, NULL); } return (1 << VDEV_RAIDZ_P); } static int vdev_raidz_reconstruct_q(raidz_map_t *rm, int *tgts, int ntgts) { int x = tgts[0]; int c, exp; abd_t *dst, *src; ASSERT(ntgts == 1); ASSERT(rm->rm_col[x].rc_size <= rm->rm_col[VDEV_RAIDZ_Q].rc_size); for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { uint64_t size = (c == x) ? 0 : MIN(rm->rm_col[x].rc_size, rm->rm_col[c].rc_size); src = rm->rm_col[c].rc_abd; dst = rm->rm_col[x].rc_abd; if (c == rm->rm_firstdatacol) { if (dst != src) { ASSERT3S(dst->abd_size, >=, size); ASSERT3S(src->abd_size, >=, size); abd_copy_off(dst, src, 0, 0, size); } if (rm->rm_col[x].rc_size > size) abd_zero_off(dst, size, rm->rm_col[x].rc_size - size); } else { ASSERT3U(size, <=, rm->rm_col[x].rc_size); if (src != dst) (void) abd_iterate_func2(dst, src, 0, 0, size, vdev_raidz_reconst_q_pre_func, NULL); (void) abd_iterate_func(dst, size, rm->rm_col[x].rc_size - size, vdev_raidz_reconst_q_pre_tail_func, NULL); } } src = rm->rm_col[VDEV_RAIDZ_Q].rc_abd; dst = rm->rm_col[x].rc_abd; exp = 255 - (rm->rm_cols - 1 - x); struct reconst_q_struct rq = { abd_to_buf(src), exp }; (void) abd_iterate_func(dst, 0, rm->rm_col[x].rc_size, vdev_raidz_reconst_q_post_func, &rq); return (1 << VDEV_RAIDZ_Q); } static int vdev_raidz_reconstruct_pq(raidz_map_t *rm, 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 >= 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_abd; qdata = rm->rm_col[VDEV_RAIDZ_Q].rc_abd; xsize = rm->rm_col[x].rc_size; ysize = rm->rm_col[y].rc_size; rm->rm_col[VDEV_RAIDZ_P].rc_abd = abd_alloc_linear(rm->rm_col[VDEV_RAIDZ_P].rc_size, B_TRUE); rm->rm_col[VDEV_RAIDZ_Q].rc_abd = abd_alloc_linear(rm->rm_col[VDEV_RAIDZ_Q].rc_size, B_TRUE); 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 = abd_to_buf(pdata); q = abd_to_buf(qdata); pxy = abd_to_buf(rm->rm_col[VDEV_RAIDZ_P].rc_abd); qxy = abd_to_buf(rm->rm_col[VDEV_RAIDZ_Q].rc_abd); xd = rm->rm_col[x].rc_abd; yd = rm->rm_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 - (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)]; 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(rm->rm_col[VDEV_RAIDZ_P].rc_abd); abd_free(rm->rm_col[VDEV_RAIDZ_Q].rc_abd); /* * Restore the saved parity data. */ rm->rm_col[VDEV_RAIDZ_P].rc_abd = pdata; rm->rm_col[VDEV_RAIDZ_Q].rc_abd = qdata; return ((1 << VDEV_RAIDZ_P) | (1 << VDEV_RAIDZ_Q)); } /* BEGIN CSTYLED */ /* * In the general case of reconstruction, we must solve the system of linear * equations defined by the coeffecients 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 coeffecients 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 | * | 19 205 116 29 64 16 4 1 | * | 1 0 0 0 0 0 0 0 | * (V|I)' = | 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. */ /* END CSTYLED */ static void vdev_raidz_matrix_init(raidz_map_t *rm, int n, int nmap, int *map, uint8_t **rows) { int i, j; int pow; ASSERT(n == rm->rm_cols - rm->rm_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_map_t *rm, 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], <, rm->rm_firstdatacol); } for (; i < n; i++) { ASSERT3S(used[i], >=, rm->rm_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], >=, rm->rm_firstdatacol); jj = used[j] - rm->rm_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_map_t *rm, 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]; uint64_t dcount[VDEV_RAIDZ_MAXPARITY]; 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, <, rm->rm_cols); src = abd_to_buf(rm->rm_col[c].rc_abd); ccount = rm->rm_col[c].rc_size; for (j = 0; j < nmissing; j++) { cc = missing[j] + rm->rm_firstdatacol; ASSERT3U(cc, >=, rm->rm_firstdatacol); ASSERT3U(cc, <, rm->rm_cols); ASSERT3U(cc, !=, c); dst[j] = abd_to_buf(rm->rm_col[cc].rc_abd); dcount[j] = rm->rm_col[cc].rc_size; } ASSERT(ccount >= rm->rm_col[missing[0]].rc_size || i > 0); 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 int vdev_raidz_reconstruct_general(raidz_map_t *rm, 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; int code = 0; /* * Matrix reconstruction can't use scatter ABDs yet, so we allocate * temporary linear ABDs. */ if (!abd_is_linear(rm->rm_col[rm->rm_firstdatacol].rc_abd)) { bufs = kmem_alloc(rm->rm_cols * sizeof (abd_t *), KM_PUSHPAGE); for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { raidz_col_t *col = &rm->rm_col[c]; bufs[c] = col->rc_abd; col->rc_abd = abd_alloc_linear(col->rc_size, B_TRUE); ASSERT3S(col->rc_abd->abd_size, >=, col->rc_size); ASSERT3S(bufs[c]->abd_size, >=, col->rc_size); abd_copy_off(col->rc_abd, bufs[c], 0, 0, col->rc_size); } } n = rm->rm_cols - rm->rm_firstdatacol; /* * Figure out which data columns are missing. */ nmissing_rows = 0; for (t = 0; t < ntgts; t++) { if (tgts[t] >= rm->rm_firstdatacol) { missing_rows[nmissing_rows++] = tgts[t] - rm->rm_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 < rm->rm_firstdatacol); /* * Skip any targeted parity columns. */ if (c == tgts[tt]) { tt++; continue; } code |= 1 << c; parity_map[i] = c; i++; } ASSERT(code != 0); ASSERT3U(code, <, 1 << VDEV_RAIDZ_MAXPARITY); 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 = rm->rm_firstdatacol; c < rm->rm_cols; c++) { if (tt < nmissing_rows && c == missing_rows[tt] + rm->rm_firstdatacol) { tt++; continue; } ASSERT3S(i, <, n); used[i] = c; i++; } /* * Initialize the interesting rows of the matrix. */ vdev_raidz_matrix_init(rm, n, nmissing_rows, parity_map, rows); /* * Invert the matrix. */ vdev_raidz_matrix_invert(rm, n, nmissing_rows, missing_rows, rows, invrows, used); /* * Reconstruct the missing data using the generated matrix. */ vdev_raidz_matrix_reconstruct(rm, n, nmissing_rows, missing_rows, invrows, used); kmem_free(p, psize); /* * copy back from temporary linear abds and free them */ if (bufs) { for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { raidz_col_t *col = &rm->rm_col[c]; ASSERT3S(bufs[c]->abd_size, >=, col->rc_size); ASSERT3S(col->rc_abd->abd_size, >=, col->rc_size); abd_copy_off(bufs[c], col->rc_abd, 0, 0, col->rc_size); abd_free(col->rc_abd); col->rc_abd = bufs[c]; } kmem_free(bufs, rm->rm_cols * sizeof (abd_t *)); } return (code); } static int vdev_raidz_reconstruct(raidz_map_t *rm, int *t, int nt) { int tgts[VDEV_RAIDZ_MAXPARITY], *dt; int ntgts; int i, c; int code; int nbadparity, nbaddata; int parity_valid[VDEV_RAIDZ_MAXPARITY]; /* * The tgts list must already be sorted. */ for (i = 1; i < nt; i++) { ASSERT(t[i] > t[i - 1]); } nbadparity = rm->rm_firstdatacol; nbaddata = rm->rm_cols - nbadparity; ntgts = 0; for (i = 0, c = 0; c < rm->rm_cols; c++) { if (c < rm->rm_firstdatacol) parity_valid[c] = B_FALSE; if (i < nt && c == t[i]) { tgts[ntgts++] = c; i++; } else if (rm->rm_col[c].rc_error != 0) { tgts[ntgts++] = c; } else if (c >= rm->rm_firstdatacol) { nbaddata--; } else { parity_valid[c] = B_TRUE; nbadparity--; } } ASSERT(ntgts >= nt); ASSERT(nbaddata >= 0); ASSERT(nbaddata + nbadparity == ntgts); dt = &tgts[nbadparity]; /* * See if we can use any of our optimized reconstruction routines. */ if (!vdev_raidz_default_to_general) { switch (nbaddata) { case 1: if (parity_valid[VDEV_RAIDZ_P]) return (vdev_raidz_reconstruct_p(rm, dt, 1)); ASSERT(rm->rm_firstdatacol > 1); if (parity_valid[VDEV_RAIDZ_Q]) return (vdev_raidz_reconstruct_q(rm, dt, 1)); ASSERT(rm->rm_firstdatacol > 2); break; case 2: ASSERT(rm->rm_firstdatacol > 1); if (parity_valid[VDEV_RAIDZ_P] && parity_valid[VDEV_RAIDZ_Q]) return (vdev_raidz_reconstruct_pq(rm, dt, 2)); ASSERT(rm->rm_firstdatacol > 2); break; } } code = vdev_raidz_reconstruct_general(rm, tgts, ntgts); ASSERT(code < (1 << VDEV_RAIDZ_MAXPARITY)); ASSERT(code > 0); return (code); } static int vdev_raidz_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize, uint64_t *ashift) { vdev_t *cvd; uint64_t nparity = vd->vdev_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++) { 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; *ashift = MAX(*ashift, cvd->vdev_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) { int c; for (c = 0; c < vd->vdev_children; c++) vdev_close(vd->vdev_child[c]); } /* * Handle a read or write I/O to a RAID-Z dump device. * * The dump device is in a unique situation compared to other ZFS datasets: * writing to this device should be as simple and fast as possible. In * addition, durability matters much less since the dump will be extracted * once the machine reboots. For that reason, this function eschews parity for * performance and simplicity. The dump device uses the checksum setting * ZIO_CHECKSUM_NOPARITY to indicate that parity is not maintained for this * dataset. * * Blocks of size 128 KB have been preallocated for this volume. I/Os less than * 128 KB will not fill an entire block; in addition, they may not be properly * aligned. In that case, this function uses the preallocated 128 KB block and * omits reading or writing any "empty" portions of that block, as opposed to * allocating a fresh appropriately-sized block. * * Looking at an example of a 32 KB I/O to a RAID-Z vdev with 5 child vdevs: * * vdev_raidz_io_start(data, size: 32 KB, offset: 64 KB) * * If this were a standard RAID-Z dataset, a block of at least 40 KB would be * allocated which spans all five child vdevs. 8 KB of data would be written to * each of four vdevs, with the fifth containing the parity bits. * * parity data data data data * | PP | XX | XX | XX | XX | * ^ ^ ^ ^ ^ * | | | | | * 8 KB parity ------8 KB data blocks------ * * However, when writing to the dump device, the behavior is different: * * vdev_raidz_physio(data, size: 32 KB, offset: 64 KB) * * Unlike the normal RAID-Z case in which the block is allocated based on the * I/O size, reads and writes here always use a 128 KB logical I/O size. If the * I/O size is less than 128 KB, only the actual portions of data are written. * In this example the data is written to the third data vdev since that vdev * contains the offset [64 KB, 96 KB). * * parity data data data data * | | | | XX | | * ^ * | * 32 KB data block * * As a result, an individual I/O may not span all child vdevs; moreover, a * small I/O may only operate on a single child vdev. * * Note that since there are no parity bits calculated or written, this format * remains the same no matter how many parity bits are used in a normal RAID-Z * stripe. On a RAID-Z3 configuration with seven child vdevs, the example above * would look like: * * parity parity parity data data data data * | | | | | | XX | | * ^ * | * 32 KB data block */ int vdev_raidz_physio(vdev_t *vd, caddr_t data, size_t size, uint64_t offset, uint64_t origoffset, boolean_t doread, boolean_t isdump) { vdev_t *tvd = vd->vdev_top; vdev_t *cvd; raidz_map_t *rm; raidz_col_t *rc; int c, err = 0; uint64_t start, end, colstart, colend; uint64_t coloffset, colsize, colskip; int flags = doread ? B_READ : B_WRITE; #ifdef _KERNEL /* * Don't write past the end of the block */ VERIFY3U(offset + size, <=, origoffset + SPA_OLD_MAXBLOCKSIZE); start = offset; end = start + size; /* * Allocate a RAID-Z map for this block. Note that this block starts * from the "original" offset, this is, the offset of the extent which * contains the requisite offset of the data being read or written. * * Even if this I/O operation doesn't span the full block size, let's * treat the on-disk format as if the only blocks are the complete 128 * KB size. */ abd_t *abd = abd_get_from_buf(data - (offset - origoffset), SPA_OLD_MAXBLOCKSIZE); rm = vdev_raidz_map_alloc(abd, SPA_OLD_MAXBLOCKSIZE, origoffset, tvd->vdev_ashift, vd->vdev_children, vd->vdev_nparity); coloffset = origoffset; for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++, coloffset += rc->rc_size) { rc = &rm->rm_col[c]; cvd = vd->vdev_child[rc->rc_devidx]; /* * Find the start and end of this column in the RAID-Z map, * keeping in mind that the stated size and offset of the * operation may not fill the entire column for this vdev. * * If any portion of the data spans this column, issue the * appropriate operation to the vdev. */ if (coloffset + rc->rc_size <= start) continue; if (coloffset >= end) continue; colstart = MAX(coloffset, start); colend = MIN(end, coloffset + rc->rc_size); colsize = colend - colstart; colskip = colstart - coloffset; VERIFY3U(colsize, <=, rc->rc_size); VERIFY3U(colskip, <=, rc->rc_size); /* * Note that the child vdev will have a vdev label at the start * of its range of offsets, hence the need for * VDEV_LABEL_OFFSET(). See zio_vdev_child_io() for another * example of why this calculation is needed. */ if ((err = vdev_disk_physio(cvd, ((char *)abd_to_buf(rc->rc_abd)) + colskip, colsize, VDEV_LABEL_OFFSET(rc->rc_offset) + colskip, flags, isdump)) != 0) break; } vdev_raidz_map_free(rm); abd_put(abd); #endif /* KERNEL */ return (err); } static uint64_t vdev_raidz_asize(vdev_t *vd, uint64_t psize) { uint64_t asize; uint64_t ashift = vd->vdev_top->vdev_ashift; uint64_t cols = vd->vdev_children; uint64_t nparity = vd->vdev_nparity; asize = ((psize - 1) >> ashift) + 1; asize += nparity * ((asize + cols - nparity - 1) / (cols - nparity)); asize = roundup(asize, nparity + 1) << ashift; return (asize); } static void vdev_raidz_child_done(zio_t *zio) { raidz_col_t *rc = zio->io_private; rc->rc_error = zio->io_error; rc->rc_tried = 1; rc->rc_skipped = 0; } static void vdev_raidz_io_verify(zio_t *zio, raidz_map_t *rm, int col) { #ifdef ZFS_DEBUG vdev_t *vd = zio->io_vd; vdev_t *tvd = vd->vdev_top; range_seg_t logical_rs, physical_rs; logical_rs.rs_start = zio->io_offset; logical_rs.rs_end = logical_rs.rs_start + vdev_raidz_asize(zio->io_vd, zio->io_size); raidz_col_t *rc = &rm->rm_col[col]; vdev_t *cvd = vd->vdev_child[rc->rc_devidx]; vdev_xlate(cvd, &logical_rs, &physical_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 } /* * 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_t *cvd; raidz_map_t *rm; raidz_col_t *rc; int c, i; rm = vdev_raidz_map_alloc(zio->io_abd, zio->io_size, zio->io_offset, tvd->vdev_ashift, vd->vdev_children, vd->vdev_nparity); zio->io_vsd = rm; zio->io_vsd_ops = &vdev_raidz_vsd_ops; ASSERT3U(rm->rm_asize, ==, vdev_psize_to_asize(vd, zio->io_size)); if (zio->io_type == ZIO_TYPE_WRITE) { vdev_raidz_generate_parity(rm); for (c = 0; c < rm->rm_cols; c++) { rc = &rm->rm_col[c]; cvd = vd->vdev_child[rc->rc_devidx]; /* * Verify physical to logical translation. */ vdev_raidz_io_verify(zio, rm, c); 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)); } /* * Generate optional I/Os for any skipped sectors to improve * aggregation contiguity. */ for (c = rm->rm_skipstart, i = 0; i < rm->rm_nskip; c++, i++) { ASSERT(c <= rm->rm_scols); if (c == rm->rm_scols) c = 0; 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_size, NULL, 1 << tvd->vdev_ashift, zio->io_type, zio->io_priority, ZIO_FLAG_NODATA | ZIO_FLAG_OPTIONAL, NULL, NULL)); } zio_execute(zio); return; } ASSERT(zio->io_type == ZIO_TYPE_READ); /* * Iterate over the columns in reverse order so that we hit the parity * last -- any errors along the way will force us to read the parity. */ 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 = 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 >= rm->rm_firstdatacol) rm->rm_missingdata++; else rm->rm_missingparity++; rc->rc_error = SET_ERROR(ESTALE); rc->rc_skipped = 1; continue; } if (c >= rm->rm_firstdatacol || rm->rm_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)); } } zio_execute(zio); } /* * Report a checksum error for a child of a RAID-Z device. */ static void raidz_checksum_error(zio_t *zio, raidz_col_t *rc, abd_t *bad_data) { vdev_t *vd = zio->io_vd->vdev_child[rc->rc_devidx]; if (!(zio->io_flags & ZIO_FLAG_SPECULATIVE)) { zio_bad_cksum_t zbc; raidz_map_t *rm = zio->io_vsd; mutex_enter(&vd->vdev_stat_lock); vd->vdev_stat.vs_checksum_errors++; mutex_exit(&vd->vdev_stat_lock); zbc.zbc_has_cksum = 0; zbc.zbc_injected = rm->rm_ecksuminjected; zfs_ereport_post_checksum(zio->io_spa, vd, &zio->io_bookmark, zio, rc->rc_offset, rc->rc_size, rc->rc_abd, bad_data, &zbc); } } /* * 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; 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 such failures. */ static int raidz_parity_verify(zio_t *zio, raidz_map_t *rm) { abd_t *orig[VDEV_RAIDZ_MAXPARITY]; int c, ret = 0; 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 < rm->rm_firstdatacol; c++) { rc = &rm->rm_col[c]; if (!rc->rc_tried || rc->rc_error != 0) continue; orig[c] = abd_alloc_sametype(rc->rc_abd, rc->rc_size); abd_copy(orig[c], rc->rc_abd, rc->rc_size); } vdev_raidz_generate_parity(rm); for (c = 0; c < rm->rm_firstdatacol; c++) { rc = &rm->rm_col[c]; if (!rc->rc_tried || rc->rc_error != 0) continue; if (abd_cmp(orig[c], rc->rc_abd, rc->rc_abd->abd_size) != 0) { raidz_checksum_error(zio, rc, orig[c]); rc->rc_error = SET_ERROR(ECKSUM); ret++; } abd_free(orig[c]); } return (ret); } /* * Keep statistics on all the ways that we used parity to correct data. */ static uint64_t raidz_corrected[1 << VDEV_RAIDZ_MAXPARITY]; 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); } /* * Iterate over all combinations of bad data 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. */ static int vdev_raidz_combrec(zio_t *zio, int total_errors, int data_errors) { raidz_map_t *rm = zio->io_vsd; raidz_col_t *rc; abd_t *orig[VDEV_RAIDZ_MAXPARITY]; int tstore[VDEV_RAIDZ_MAXPARITY + 2]; int *tgts = &tstore[1]; int current, next, i, c, n; int code, ret = 0; ASSERT(total_errors < rm->rm_firstdatacol); /* * This simplifies one edge condition. */ tgts[-1] = -1; for (n = 1; n <= rm->rm_firstdatacol - total_errors; n++) { /* * Initialize the targets array by finding the first n columns * that contain no error. * * If there were no data errors, we need to ensure that we're * always explicitly attempting to reconstruct at least one * data column. To do this, we simply push the highest target * up into the data columns. */ for (c = 0, i = 0; i < n; i++) { if (i == n - 1 && data_errors == 0 && c < rm->rm_firstdatacol) { c = rm->rm_firstdatacol; } while (rm->rm_col[c].rc_error != 0) { c++; ASSERT3S(c, <, rm->rm_cols); } tgts[i] = c++; } /* * Setting tgts[n] simplifies the other edge condition. */ tgts[n] = rm->rm_cols; /* * These buffers were allocated in previous iterations. */ for (i = 0; i < n - 1; i++) { ASSERT(orig[i] != NULL); } orig[n - 1] = abd_alloc_sametype(rm->rm_col[0].rc_abd, rm->rm_col[0].rc_size); current = 0; next = tgts[current]; while (current != n) { tgts[current] = next; current = 0; /* * Save off the original data that we're going to * attempt to reconstruct. */ for (i = 0; i < n; i++) { ASSERT(orig[i] != NULL); c = tgts[i]; ASSERT3S(c, >=, 0); ASSERT3S(c, <, rm->rm_cols); rc = &rm->rm_col[c]; ASSERT3S(orig[i]->abd_size, >=, rc->rc_size); ASSERT3S(rc->rc_abd->abd_size, >=, rc->rc_size); abd_copy_off(orig[i], rc->rc_abd, 0, 0, rc->rc_size); } /* * Attempt a reconstruction and exit the outer loop on * success. */ code = vdev_raidz_reconstruct(rm, tgts, n); if (raidz_checksum_verify(zio) == 0) { atomic_inc_64(&raidz_corrected[code]); for (i = 0; i < n; i++) { c = tgts[i]; rc = &rm->rm_col[c]; ASSERT(rc->rc_error == 0); if (rc->rc_tried) raidz_checksum_error(zio, rc, orig[i]); rc->rc_error = SET_ERROR(ECKSUM); } ret = code; goto done; } /* * Restore the original data. */ for (i = 0; i < n; i++) { c = tgts[i]; rc = &rm->rm_col[c]; ASSERT3S(rc->rc_abd->abd_size, >=, rc->rc_size); ASSERT3S(orig[i]->abd_size, >=, rc->rc_size); abd_copy_off(rc->rc_abd, orig[i], 0, 0, rc->rc_size); } do { /* * Find the next valid column after the current * position.. */ for (next = tgts[current] + 1; next < rm->rm_cols && rm->rm_col[next].rc_error != 0; next++) continue; ASSERT(next <= tgts[current + 1]); /* * If that spot is available, we're done here. */ if (next != tgts[current + 1]) break; /* * Otherwise, find the next valid column after * the previous position. */ for (c = tgts[current - 1] + 1; rm->rm_col[c].rc_error != 0; c++) continue; tgts[current] = c; current++; } while (current != n); } } n--; done: for (i = 0; i < n; i++) abd_free(orig[i]); return (ret); } /* * Complete an IO operation on a RAIDZ VDev * * Outline: * - For write operations: * 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. * - For read operations: * 1. Check for errors on the child IOs. * 2. If data errors occurred: * a. Try to reassemble the data from the parity available. * b. If we haven't yet read the parity drives, read them now. * c. If all parity drives have been read but the data still doesn't * reassemble with a correct checksum, then try combinatorial * reconstruction. * d. If that doesn't work, return an error. * 3. If there were unexpected errors or this is a resilver operation, * rewrite the vdevs that had errors. */ 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; int unexpected_errors = 0; int parity_errors = 0; int parity_untried = 0; int data_errors = 0; int total_errors = 0; int n, c; int tgts[VDEV_RAIDZ_MAXPARITY]; int code; 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) { if (data_errors == 0) { if (raidz_checksum_verify(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; } } else { /* * 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); /* * Identify the data columns that reported an error. */ n = 0; for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) { rc = &rm->rm_col[c]; if (rc->rc_error != 0) { ASSERT(n < VDEV_RAIDZ_MAXPARITY); tgts[n++] = c; } } ASSERT(rm->rm_firstdatacol >= n); code = vdev_raidz_reconstruct(rm, tgts, n); if (raidz_checksum_verify(zio) == 0) { atomic_inc_64(&raidz_corrected[code]); /* * If we read more parity disks than were used * for reconstruction, confirm that the other * parity disks produced correct data. This * routine is suboptimal in that it regenerates * the parity that we already used in addition * to the parity that we're attempting to * verify, but this should be a relatively * uncommon case, and can be optimized if it * becomes a problem. Note that we regenerate * parity when resilvering so we can write it * out to failed devices later. */ if (parity_errors < rm->rm_firstdatacol - n || (zio->io_flags & ZIO_FLAG_RESILVER)) { n = raidz_parity_verify(zio, rm); unexpected_errors += n; ASSERT(parity_errors + n <= rm->rm_firstdatacol); } goto done; } } } /* * 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_abd, 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. We check if there is enough additional data to * possibly reconstruct the data and then perform combinatorial * reconstruction over all possible combinations. If that fails, * we're cooked. */ if (total_errors > rm->rm_firstdatacol) { zio->io_error = vdev_raidz_worst_error(rm); } else if (total_errors < rm->rm_firstdatacol && (code = vdev_raidz_combrec(zio, total_errors, data_errors)) != 0) { /* * If we didn't use all the available parity for the * combinatorial reconstruction, verify that the remaining * parity is correct. */ if (code != (1 << rm->rm_firstdatacol) - 1) (void) raidz_parity_verify(zio, rm); } else { /* * We're here because either: * * total_errors == rm_first_datacol, or * vdev_raidz_combrec() failed * * In either case, there is enough bad data to prevent * reconstruction. * * Start checksum ereports for all children which haven't * failed, and the IO wasn't speculative. */ zio->io_error = SET_ERROR(ECKSUM); if (!(zio->io_flags & ZIO_FLAG_SPECULATIVE)) { for (c = 0; c < rm->rm_cols; c++) { rc = &rm->rm_col[c]; if (rc->rc_error == 0) { zio_bad_cksum_t zbc; zbc.zbc_has_cksum = 0; zbc.zbc_injected = rm->rm_ecksuminjected; zfs_ereport_start_checksum( zio->io_spa, vd->vdev_child[rc->rc_devidx], &zio->io_bookmark, zio, rc->rc_offset, rc->rc_size, (void *)(uintptr_t)c, &zbc); } } } } done: zio_checksum_verified(zio); if (zio->io_error == 0 && spa_writeable(zio->io_spa) && (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_abd, rc->rc_size, ZIO_TYPE_WRITE, ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_IO_REPAIR | (unexpected_errors ? ZIO_FLAG_SELF_HEAL : 0), 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); } /* * 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 imples that full stripe * width blocks must be resilvered. */ static boolean_t vdev_raidz_need_resilver(vdev_t *vd, uint64_t offset, size_t psize) { uint64_t dcols = vd->vdev_children; uint64_t nparity = vd->vdev_nparity; uint64_t ashift = vd->vdev_top->vdev_ashift; /* The starting RAIDZ (parent) vdev sector of the block. */ uint64_t b = offset >> 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; 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_seg_t *in, range_seg_t *res) { 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(in->rs_start % (1 << ashift)); ASSERT0(in->rs_end % (1 << ashift)); uint64_t b_start = in->rs_start >> ashift; uint64_t b_end = in->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; res->rs_start = start_row << ashift; res->rs_end = end_row << ashift; ASSERT3U(res->rs_start, <=, in->rs_start); ASSERT3U(res->rs_end - res->rs_start, <=, in->rs_end - in->rs_start); } vdev_ops_t vdev_raidz_ops = { .vdev_op_open = vdev_raidz_open, .vdev_op_close = vdev_raidz_close, .vdev_op_asize = vdev_raidz_asize, .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_type = VDEV_TYPE_RAIDZ, /* name of this vdev type */ .vdev_op_leaf = B_FALSE /* not a leaf vdev */ };