diff options
Diffstat (limited to 'sys/cddl')
| -rw-r--r-- | sys/cddl/boot/zfs/README | 2 | ||||
| -rw-r--r-- | sys/cddl/boot/zfs/zfsimpl.h | 11 | ||||
| -rw-r--r-- | sys/cddl/boot/zfs/zfssubr.c | 732 |
3 files changed, 742 insertions, 3 deletions
diff --git a/sys/cddl/boot/zfs/README b/sys/cddl/boot/zfs/README index 4b62181..d36e02e 100644 --- a/sys/cddl/boot/zfs/README +++ b/sys/cddl/boot/zfs/README @@ -6,7 +6,7 @@ are used by the ZFS bootstrap: fletcher.c checksum support sha256.c checksum support lzjb.c compression support - zfssubr.c mostly checksum and compression support + zfssubr.c checksum, compression and raidz support zfsimpl.h mostly describing the physical layout The files fletcher.c, lzjb.c and sha256.c are largely identical to the diff --git a/sys/cddl/boot/zfs/zfsimpl.h b/sys/cddl/boot/zfs/zfsimpl.h index 7796d8e..a0b7b72 100644 --- a/sys/cddl/boot/zfs/zfsimpl.h +++ b/sys/cddl/boot/zfs/zfsimpl.h @@ -1137,7 +1137,10 @@ typedef struct znode_phys { * In-core vdev representation. */ struct vdev; -typedef int vdev_read_t(struct vdev *vdev, void *priv, off_t offset, void *buf, size_t bytes); +typedef int vdev_phys_read_t(struct vdev *vdev, void *priv, + off_t offset, void *buf, size_t bytes); +typedef int vdev_read_t(struct vdev *vdev, const blkptr_t *bp, + void *buf, off_t offset, size_t bytes); typedef STAILQ_HEAD(vdev_list, vdev) vdev_list_t; @@ -1148,8 +1151,12 @@ typedef struct vdev { char *v_name; /* vdev name */ uint64_t v_guid; /* vdev guid */ int v_id; /* index in parent */ + int v_ashift; /* offset to block shift */ + int v_nparity; /* # parity for raidz */ + int v_nchildren; /* # children */ vdev_state_t v_state; /* current state */ - vdev_read_t *v_read; /* function to read from this vdev */ + vdev_phys_read_t *v_phys_read; /* read from raw leaf vdev */ + vdev_read_t *v_read; /* read from vdev */ void *v_read_priv; /* private data for read function */ } vdev_t; diff --git a/sys/cddl/boot/zfs/zfssubr.c b/sys/cddl/boot/zfs/zfssubr.c index 40bb863..fb4444f 100644 --- a/sys/cddl/boot/zfs/zfssubr.c +++ b/sys/cddl/boot/zfs/zfssubr.c @@ -191,3 +191,735 @@ zap_hash(uint64_t salt, const char *name) return (crc); } + +static char *zfs_alloc_temp(size_t sz); + +typedef struct raidz_col { + uint64_t rc_devidx; /* child device index for I/O */ + uint64_t rc_offset; /* device offset */ + uint64_t rc_size; /* I/O size */ + void *rc_data; /* I/O data */ + int rc_error; /* I/O error for this device */ + uint8_t rc_tried; /* Did we attempt this I/O column? */ + uint8_t rc_skipped; /* Did we skip this I/O column? */ +} raidz_col_t; + +#define VDEV_RAIDZ_P 0 +#define VDEV_RAIDZ_Q 1 + +static void +vdev_raidz_reconstruct_p(raidz_col_t *cols, int nparity, int acols, int x) +{ + uint64_t *dst, *src, xcount, ccount, count, i; + int c; + + xcount = cols[x].rc_size / sizeof (src[0]); + //ASSERT(xcount <= cols[VDEV_RAIDZ_P].rc_size / sizeof (src[0])); + //ASSERT(xcount > 0); + + src = cols[VDEV_RAIDZ_P].rc_data; + dst = cols[x].rc_data; + for (i = 0; i < xcount; i++, dst++, src++) { + *dst = *src; + } + + for (c = nparity; c < acols; c++) { + src = cols[c].rc_data; + dst = cols[x].rc_data; + + if (c == x) + continue; + + ccount = cols[c].rc_size / sizeof (src[0]); + count = MIN(ccount, xcount); + + for (i = 0; i < count; i++, dst++, src++) { + *dst ^= *src; + } + } +} + +/* + * These two tables represent powers and logs of 2 in the Galois field defined + * above. These values were computed by repeatedly multiplying by 2 as above. + */ +static const uint8_t vdev_raidz_pow2[256] = { + 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, + 0x1d, 0x3a, 0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26, + 0x4c, 0x98, 0x2d, 0x5a, 0xb4, 0x75, 0xea, 0xc9, + 0x8f, 0x03, 0x06, 0x0c, 0x18, 0x30, 0x60, 0xc0, + 0x9d, 0x27, 0x4e, 0x9c, 0x25, 0x4a, 0x94, 0x35, + 0x6a, 0xd4, 0xb5, 0x77, 0xee, 0xc1, 0x9f, 0x23, + 0x46, 0x8c, 0x05, 0x0a, 0x14, 0x28, 0x50, 0xa0, + 0x5d, 0xba, 0x69, 0xd2, 0xb9, 0x6f, 0xde, 0xa1, + 0x5f, 0xbe, 0x61, 0xc2, 0x99, 0x2f, 0x5e, 0xbc, + 0x65, 0xca, 0x89, 0x0f, 0x1e, 0x3c, 0x78, 0xf0, + 0xfd, 0xe7, 0xd3, 0xbb, 0x6b, 0xd6, 0xb1, 0x7f, + 0xfe, 0xe1, 0xdf, 0xa3, 0x5b, 0xb6, 0x71, 0xe2, + 0xd9, 0xaf, 0x43, 0x86, 0x11, 0x22, 0x44, 0x88, + 0x0d, 0x1a, 0x34, 0x68, 0xd0, 0xbd, 0x67, 0xce, + 0x81, 0x1f, 0x3e, 0x7c, 0xf8, 0xed, 0xc7, 0x93, + 0x3b, 0x76, 0xec, 0xc5, 0x97, 0x33, 0x66, 0xcc, + 0x85, 0x17, 0x2e, 0x5c, 0xb8, 0x6d, 0xda, 0xa9, + 0x4f, 0x9e, 0x21, 0x42, 0x84, 0x15, 0x2a, 0x54, + 0xa8, 0x4d, 0x9a, 0x29, 0x52, 0xa4, 0x55, 0xaa, + 0x49, 0x92, 0x39, 0x72, 0xe4, 0xd5, 0xb7, 0x73, + 0xe6, 0xd1, 0xbf, 0x63, 0xc6, 0x91, 0x3f, 0x7e, + 0xfc, 0xe5, 0xd7, 0xb3, 0x7b, 0xf6, 0xf1, 0xff, + 0xe3, 0xdb, 0xab, 0x4b, 0x96, 0x31, 0x62, 0xc4, + 0x95, 0x37, 0x6e, 0xdc, 0xa5, 0x57, 0xae, 0x41, + 0x82, 0x19, 0x32, 0x64, 0xc8, 0x8d, 0x07, 0x0e, + 0x1c, 0x38, 0x70, 0xe0, 0xdd, 0xa7, 0x53, 0xa6, + 0x51, 0xa2, 0x59, 0xb2, 0x79, 0xf2, 0xf9, 0xef, + 0xc3, 0x9b, 0x2b, 0x56, 0xac, 0x45, 0x8a, 0x09, + 0x12, 0x24, 0x48, 0x90, 0x3d, 0x7a, 0xf4, 0xf5, + 0xf7, 0xf3, 0xfb, 0xeb, 0xcb, 0x8b, 0x0b, 0x16, + 0x2c, 0x58, 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83, + 0x1b, 0x36, 0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x01 +}; +static const uint8_t vdev_raidz_log2[256] = { + 0x00, 0x00, 0x01, 0x19, 0x02, 0x32, 0x1a, 0xc6, + 0x03, 0xdf, 0x33, 0xee, 0x1b, 0x68, 0xc7, 0x4b, + 0x04, 0x64, 0xe0, 0x0e, 0x34, 0x8d, 0xef, 0x81, + 0x1c, 0xc1, 0x69, 0xf8, 0xc8, 0x08, 0x4c, 0x71, + 0x05, 0x8a, 0x65, 0x2f, 0xe1, 0x24, 0x0f, 0x21, + 0x35, 0x93, 0x8e, 0xda, 0xf0, 0x12, 0x82, 0x45, + 0x1d, 0xb5, 0xc2, 0x7d, 0x6a, 0x27, 0xf9, 0xb9, + 0xc9, 0x9a, 0x09, 0x78, 0x4d, 0xe4, 0x72, 0xa6, + 0x06, 0xbf, 0x8b, 0x62, 0x66, 0xdd, 0x30, 0xfd, + 0xe2, 0x98, 0x25, 0xb3, 0x10, 0x91, 0x22, 0x88, + 0x36, 0xd0, 0x94, 0xce, 0x8f, 0x96, 0xdb, 0xbd, + 0xf1, 0xd2, 0x13, 0x5c, 0x83, 0x38, 0x46, 0x40, + 0x1e, 0x42, 0xb6, 0xa3, 0xc3, 0x48, 0x7e, 0x6e, + 0x6b, 0x3a, 0x28, 0x54, 0xfa, 0x85, 0xba, 0x3d, + 0xca, 0x5e, 0x9b, 0x9f, 0x0a, 0x15, 0x79, 0x2b, + 0x4e, 0xd4, 0xe5, 0xac, 0x73, 0xf3, 0xa7, 0x57, + 0x07, 0x70, 0xc0, 0xf7, 0x8c, 0x80, 0x63, 0x0d, + 0x67, 0x4a, 0xde, 0xed, 0x31, 0xc5, 0xfe, 0x18, + 0xe3, 0xa5, 0x99, 0x77, 0x26, 0xb8, 0xb4, 0x7c, + 0x11, 0x44, 0x92, 0xd9, 0x23, 0x20, 0x89, 0x2e, + 0x37, 0x3f, 0xd1, 0x5b, 0x95, 0xbc, 0xcf, 0xcd, + 0x90, 0x87, 0x97, 0xb2, 0xdc, 0xfc, 0xbe, 0x61, + 0xf2, 0x56, 0xd3, 0xab, 0x14, 0x2a, 0x5d, 0x9e, + 0x84, 0x3c, 0x39, 0x53, 0x47, 0x6d, 0x41, 0xa2, + 0x1f, 0x2d, 0x43, 0xd8, 0xb7, 0x7b, 0xa4, 0x76, + 0xc4, 0x17, 0x49, 0xec, 0x7f, 0x0c, 0x6f, 0xf6, + 0x6c, 0xa1, 0x3b, 0x52, 0x29, 0x9d, 0x55, 0xaa, + 0xfb, 0x60, 0x86, 0xb1, 0xbb, 0xcc, 0x3e, 0x5a, + 0xcb, 0x59, 0x5f, 0xb0, 0x9c, 0xa9, 0xa0, 0x51, + 0x0b, 0xf5, 0x16, 0xeb, 0x7a, 0x75, 0x2c, 0xd7, + 0x4f, 0xae, 0xd5, 0xe9, 0xe6, 0xe7, 0xad, 0xe8, + 0x74, 0xd6, 0xf4, 0xea, 0xa8, 0x50, 0x58, 0xaf, +}; + +/* + * Multiply a given number by 2 raised to the given power. + */ +static uint8_t +vdev_raidz_exp2(uint8_t a, int exp) +{ + if (a == 0) + return (0); + + //ASSERT(exp >= 0); + //ASSERT(vdev_raidz_log2[a] > 0 || a == 1); + + exp += vdev_raidz_log2[a]; + if (exp > 255) + exp -= 255; + + return (vdev_raidz_pow2[exp]); +} + +static void +vdev_raidz_generate_parity_pq(raidz_col_t *cols, int nparity, int acols) +{ + uint64_t *q, *p, *src, pcount, ccount, mask, i; + int c; + + pcount = cols[VDEV_RAIDZ_P].rc_size / sizeof (src[0]); + //ASSERT(cols[VDEV_RAIDZ_P].rc_size == cols[VDEV_RAIDZ_Q].rc_size); + + for (c = nparity; c < acols; c++) { + src = cols[c].rc_data; + p = cols[VDEV_RAIDZ_P].rc_data; + q = cols[VDEV_RAIDZ_Q].rc_data; + ccount = cols[c].rc_size / sizeof (src[0]); + + if (c == nparity) { + //ASSERT(ccount == pcount || ccount == 0); + for (i = 0; i < ccount; i++, p++, q++, src++) { + *q = *src; + *p = *src; + } + for (; i < pcount; i++, p++, q++, src++) { + *q = 0; + *p = 0; + } + } else { + //ASSERT(ccount <= pcount); + + /* + * Rather than multiplying each byte + * individually (as described above), we are + * able to handle 8 at once by generating a + * mask based on the high bit in each byte and + * using that to conditionally XOR in 0x1d. + */ + for (i = 0; i < ccount; i++, p++, q++, src++) { + mask = *q & 0x8080808080808080ULL; + mask = (mask << 1) - (mask >> 7); + *q = ((*q << 1) & 0xfefefefefefefefeULL) ^ + (mask & 0x1d1d1d1d1d1d1d1dULL); + *q ^= *src; + *p ^= *src; + } + + /* + * Treat short columns as though they are full of 0s. + */ + for (; i < pcount; i++, q++) { + mask = *q & 0x8080808080808080ULL; + mask = (mask << 1) - (mask >> 7); + *q = ((*q << 1) & 0xfefefefefefefefeULL) ^ + (mask & 0x1d1d1d1d1d1d1d1dULL); + } + } + } +} + +static void +vdev_raidz_reconstruct_q(raidz_col_t *cols, int nparity, int acols, int x) +{ + uint64_t *dst, *src, xcount, ccount, count, mask, i; + uint8_t *b; + int c, j, exp; + + xcount = cols[x].rc_size / sizeof (src[0]); + //ASSERT(xcount <= cols[VDEV_RAIDZ_Q].rc_size / sizeof (src[0])); + + for (c = nparity; c < acols; c++) { + src = cols[c].rc_data; + dst = cols[x].rc_data; + + if (c == x) + ccount = 0; + else + ccount = cols[c].rc_size / sizeof (src[0]); + + count = MIN(ccount, xcount); + + if (c == nparity) { + for (i = 0; i < count; i++, dst++, src++) { + *dst = *src; + } + for (; i < xcount; i++, dst++) { + *dst = 0; + } + + } else { + /* + * For an explanation of this, see the comment in + * vdev_raidz_generate_parity_pq() above. + */ + for (i = 0; i < count; i++, dst++, src++) { + mask = *dst & 0x8080808080808080ULL; + mask = (mask << 1) - (mask >> 7); + *dst = ((*dst << 1) & 0xfefefefefefefefeULL) ^ + (mask & 0x1d1d1d1d1d1d1d1dULL); + *dst ^= *src; + } + + for (; i < xcount; i++, dst++) { + mask = *dst & 0x8080808080808080ULL; + mask = (mask << 1) - (mask >> 7); + *dst = ((*dst << 1) & 0xfefefefefefefefeULL) ^ + (mask & 0x1d1d1d1d1d1d1d1dULL); + } + } + } + + src = cols[VDEV_RAIDZ_Q].rc_data; + dst = cols[x].rc_data; + exp = 255 - (acols - 1 - x); + + for (i = 0; i < xcount; i++, dst++, src++) { + *dst ^= *src; + for (j = 0, b = (uint8_t *)dst; j < 8; j++, b++) { + *b = vdev_raidz_exp2(*b, exp); + } + } +} + + +static void +vdev_raidz_reconstruct_pq(raidz_col_t *cols, int nparity, int acols, + int x, int y) +{ + uint8_t *p, *q, *pxy, *qxy, *xd, *yd, tmp, a, b, aexp, bexp; + void *pdata, *qdata; + uint64_t xsize, ysize, i; + + //ASSERT(x < y); + //ASSERT(x >= nparity); + //ASSERT(y < acols); + + //ASSERT(cols[x].rc_size >= cols[y].rc_size); + + /* + * Move the parity data aside -- we're going to compute parity as + * though columns x and y were full of zeros -- Pxy and Qxy. We want to + * reuse the parity generation mechanism without trashing the actual + * parity so we make those columns appear to be full of zeros by + * setting their lengths to zero. + */ + pdata = cols[VDEV_RAIDZ_P].rc_data; + qdata = cols[VDEV_RAIDZ_Q].rc_data; + xsize = cols[x].rc_size; + ysize = cols[y].rc_size; + + cols[VDEV_RAIDZ_P].rc_data = + zfs_alloc_temp(cols[VDEV_RAIDZ_P].rc_size); + cols[VDEV_RAIDZ_Q].rc_data = + zfs_alloc_temp(cols[VDEV_RAIDZ_Q].rc_size); + cols[x].rc_size = 0; + cols[y].rc_size = 0; + + vdev_raidz_generate_parity_pq(cols, nparity, acols); + + cols[x].rc_size = xsize; + cols[y].rc_size = ysize; + + p = pdata; + q = qdata; + pxy = cols[VDEV_RAIDZ_P].rc_data; + qxy = cols[VDEV_RAIDZ_Q].rc_data; + xd = cols[x].rc_data; + yd = cols[y].rc_data; + + /* + * We now have: + * Pxy = P + D_x + D_y + * Qxy = Q + 2^(ndevs - 1 - x) * D_x + 2^(ndevs - 1 - y) * D_y + * + * We can then solve for D_x: + * D_x = A * (P + Pxy) + B * (Q + Qxy) + * where + * A = 2^(x - y) * (2^(x - y) + 1)^-1 + * B = 2^(ndevs - 1 - x) * (2^(x - y) + 1)^-1 + * + * With D_x in hand, we can easily solve for D_y: + * D_y = P + Pxy + D_x + */ + + a = vdev_raidz_pow2[255 + x - y]; + b = vdev_raidz_pow2[255 - (acols - 1 - x)]; + tmp = 255 - vdev_raidz_log2[a ^ 1]; + + aexp = vdev_raidz_log2[vdev_raidz_exp2(a, tmp)]; + bexp = vdev_raidz_log2[vdev_raidz_exp2(b, tmp)]; + + for (i = 0; i < xsize; i++, p++, q++, pxy++, qxy++, xd++, yd++) { + *xd = vdev_raidz_exp2(*p ^ *pxy, aexp) ^ + vdev_raidz_exp2(*q ^ *qxy, bexp); + + if (i < ysize) + *yd = *p ^ *pxy ^ *xd; + } + + /* + * Restore the saved parity data. + */ + cols[VDEV_RAIDZ_P].rc_data = pdata; + cols[VDEV_RAIDZ_Q].rc_data = qdata; +} + +static int +vdev_raidz_read(vdev_t *vdev, const blkptr_t *bp, void *buf, + off_t offset, size_t bytes) +{ + size_t psize = BP_GET_PSIZE(bp); + vdev_t *kid; + int unit_shift = vdev->v_ashift; + int dcols = vdev->v_nchildren; + int nparity = vdev->v_nparity; + int missingdata, missingparity; + int parity_errors, data_errors, unexpected_errors, total_errors; + int parity_untried; + uint64_t b = offset >> unit_shift; + uint64_t s = psize >> unit_shift; + uint64_t f = b % dcols; + uint64_t o = (b / dcols) << unit_shift; + int q, r, c, c1, bc, col, acols, coff, devidx, asize, n; + static raidz_col_t cols[16]; + raidz_col_t *rc, *rc1; + + q = s / (dcols - nparity); + r = s - q * (dcols - nparity); + bc = (r == 0 ? 0 : r + nparity); + + acols = (q == 0 ? bc : dcols); + asize = 0; + + for (c = 0; c < acols; c++) { + col = f + c; + coff = o; + if (col >= dcols) { + col -= dcols; + coff += 1ULL << unit_shift; + } + cols[c].rc_devidx = col; + cols[c].rc_offset = coff; + cols[c].rc_size = (q + (c < bc)) << unit_shift; + cols[c].rc_data = NULL; + cols[c].rc_error = 0; + cols[c].rc_tried = 0; + cols[c].rc_skipped = 0; + asize += cols[c].rc_size; + } + + asize = roundup(asize, (nparity + 1) << unit_shift); + + for (c = 0; c < nparity; c++) { + cols[c].rc_data = zfs_alloc_temp(cols[c].rc_size); + } + + cols[c].rc_data = buf; + + for (c = c + 1; c < acols; c++) + cols[c].rc_data = (char *)cols[c - 1].rc_data + + cols[c - 1].rc_size; + + /* + * If all data stored spans all columns, there's a danger that + * parity will always be on the same device and, since parity + * isn't read during normal operation, that that device's I/O + * bandwidth won't be used effectively. We therefore switch + * the parity every 1MB. + * + * ... at least that was, ostensibly, the theory. As a + * practical matter unless we juggle the parity between all + * devices evenly, we won't see any benefit. Further, + * occasional writes that aren't a multiple of the LCM of the + * number of children and the minimum stripe width are + * sufficient to avoid pessimal behavior. Unfortunately, this + * decision created an implicit on-disk format requirement + * that we need to support for all eternity, but only for + * single-parity RAID-Z. + */ + //ASSERT(acols >= 2); + //ASSERT(cols[0].rc_size == cols[1].rc_size); + + if (nparity == 1 && (offset & (1ULL << 20))) { + devidx = cols[0].rc_devidx; + o = cols[0].rc_offset; + cols[0].rc_devidx = cols[1].rc_devidx; + cols[0].rc_offset = cols[1].rc_offset; + cols[1].rc_devidx = devidx; + cols[1].rc_offset = o; + } + + /* + * Iterate over the columns in reverse order so that we hit + * the parity last -- any errors along the way will force us + * to read the parity data. + */ + missingdata = 0; + missingparity = 0; + for (c = acols - 1; c >= 0; c--) { + rc = &cols[c]; + devidx = rc->rc_devidx; + STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) + if (kid->v_id == devidx) + break; + if (kid == NULL || kid->v_state != VDEV_STATE_HEALTHY) { + if (c >= nparity) + missingdata++; + else + missingparity++; + rc->rc_error = ENXIO; + rc->rc_tried = 1; /* don't even try */ + rc->rc_skipped = 1; + continue; + } +#if 0 + /* + * Too hard for the bootcode + */ + if (vdev_dtl_contains(&cvd->vdev_dtl_map, bp->blk_birth, 1)) { + if (c >= nparity) + rm->rm_missingdata++; + else + rm->rm_missingparity++; + rc->rc_error = ESTALE; + rc->rc_skipped = 1; + continue; + } +#endif + if (c >= nparity || missingdata > 0) { + if (rc->rc_data) + rc->rc_error = kid->v_read(kid, NULL, + rc->rc_data, rc->rc_offset, rc->rc_size); + else + rc->rc_error = ENXIO; + rc->rc_tried = 1; + rc->rc_skipped = 0; + } + } + +reconstruct: + parity_errors = 0; + data_errors = 0; + unexpected_errors = 0; + total_errors = 0; + parity_untried = 0; + for (c = 0; c < acols; c++) { + rc = &cols[c]; + + if (rc->rc_error) { + if (c < nparity) + parity_errors++; + else + data_errors++; + + if (!rc->rc_skipped) + unexpected_errors++; + + total_errors++; + } else if (c < nparity && !rc->rc_tried) { + parity_untried++; + } + } + + /* + * There are three potential phases for a read: + * 1. produce valid data from the columns read + * 2. read all disks and try again + * 3. perform combinatorial reconstruction + * + * Each phase is progressively both more expensive and less + * likely to occur. If we encounter more errors than we can + * repair or all phases fail, we have no choice but to return + * an error. + */ + + /* + * If the number of errors we saw was correctable -- less than + * or equal to the number of parity disks read -- attempt to + * produce data that has a valid checksum. Naturally, this + * case applies in the absence of any errors. + */ + if (total_errors <= nparity - parity_untried) { + switch (data_errors) { + case 0: + if (zio_checksum_error(bp, buf) == 0) + return (0); + break; + + case 1: + /* + * We either attempt to read all the parity columns or + * none of them. If we didn't try to read parity, we + * wouldn't be here in the correctable case. There must + * also have been fewer parity errors than parity + * columns or, again, we wouldn't be in this code path. + */ + //ASSERT(parity_untried == 0); + //ASSERT(parity_errors < nparity); + + /* + * Find the column that reported the error. + */ + for (c = nparity; c < acols; c++) { + rc = &cols[c]; + if (rc->rc_error != 0) + break; + } + //ASSERT(c != acols); + //ASSERT(!rc->rc_skipped || rc->rc_error == ENXIO || rc->rc_error == ESTALE); + + if (cols[VDEV_RAIDZ_P].rc_error == 0) { + vdev_raidz_reconstruct_p(cols, nparity, + acols, c); + } else { + //ASSERT(nparity > 1); + vdev_raidz_reconstruct_q(cols, nparity, + acols, c); + } + + if (zio_checksum_error(bp, buf) == 0) + return (0); + break; + + case 2: + /* + * Two data column errors require double parity. + */ + //ASSERT(nparity == 2); + + /* + * Find the two columns that reported errors. + */ + for (c = nparity; c < acols; c++) { + rc = &cols[c]; + if (rc->rc_error != 0) + break; + } + //ASSERT(c != acols); + //ASSERT(!rc->rc_skipped || rc->rc_error == ENXIO || rc->rc_error == ESTALE); + + for (c1 = c++; c < acols; c++) { + rc = &cols[c]; + if (rc->rc_error != 0) + break; + } + //ASSERT(c != acols); + //ASSERT(!rc->rc_skipped || rc->rc_error == ENXIO || rc->rc_error == ESTALE); + + vdev_raidz_reconstruct_pq(cols, nparity, acols, + c1, c); + + if (zio_checksum_error(bp, buf) == 0) + return (0); + break; + + default: + break; + //ASSERT(nparity <= 2); + //ASSERT(0); + } + } + + /* + * This isn't a typical situation -- either we got a read + * error or a child silently returned bad data. Read every + * block so we can try again with as much data and parity as + * we can track down. If we've already been through once + * before, all children will be marked as tried so we'll + * proceed to combinatorial reconstruction. + */ + n = 0; + for (c = 0; c < acols; c++) { + rc = &cols[c]; + if (rc->rc_tried) + continue; + + devidx = rc->rc_devidx; + STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) + if (kid->v_id == devidx) + break; + if (kid == NULL || kid->v_state != VDEV_STATE_HEALTHY) { + rc->rc_error = ENXIO; + rc->rc_tried = 1; /* don't even try */ + rc->rc_skipped = 1; + continue; + } + if (rc->rc_data) + rc->rc_error = kid->v_read(kid, NULL, + rc->rc_data, rc->rc_offset, rc->rc_size); + else + rc->rc_error = ENXIO; + if (rc->rc_error == 0) + n++; + rc->rc_tried = 1; + rc->rc_skipped = 0; + } + + /* + * If we managed to read anything more, retry the + * reconstruction. + */ + if (n) + goto reconstruct; + + /* + * At this point we've attempted to reconstruct the data given the + * errors we detected, and we've attempted to read all columns. There + * must, therefore, be one or more additional problems -- silent errors + * resulting in invalid data rather than explicit I/O errors resulting + * in absent data. Before we attempt combinatorial reconstruction make + * sure we have a chance of coming up with the right answer. + */ + if (total_errors >= nparity) { + return (EIO); + } + + asize = 0; + for (c = 0; c < acols; c++) { + rc = &cols[c]; + if (rc->rc_size > asize) + asize = rc->rc_size; + } + if (cols[VDEV_RAIDZ_P].rc_error == 0) { + /* + * Attempt to reconstruct the data from parity P. + */ + void *orig; + orig = zfs_alloc_temp(asize); + for (c = nparity; c < acols; c++) { + rc = &cols[c]; + + memcpy(orig, rc->rc_data, rc->rc_size); + vdev_raidz_reconstruct_p(cols, nparity, acols, c); + + if (zio_checksum_error(bp, buf) == 0) + return (0); + + memcpy(rc->rc_data, orig, rc->rc_size); + } + } + + if (nparity > 1 && cols[VDEV_RAIDZ_Q].rc_error == 0) { + /* + * Attempt to reconstruct the data from parity Q. + */ + void *orig; + orig = zfs_alloc_temp(asize); + for (c = nparity; c < acols; c++) { + rc = &cols[c]; + + memcpy(orig, rc->rc_data, rc->rc_size); + vdev_raidz_reconstruct_q(cols, nparity, acols, c); + + if (zio_checksum_error(bp, buf) == 0) + return (0); + + memcpy(rc->rc_data, orig, rc->rc_size); + } + } + + if (nparity > 1 && + cols[VDEV_RAIDZ_P].rc_error == 0 && + cols[VDEV_RAIDZ_Q].rc_error == 0) { + /* + * Attempt to reconstruct the data from both P and Q. + */ + void *orig, *orig1; + orig = zfs_alloc_temp(asize); + orig1 = zfs_alloc_temp(asize); + for (c = nparity; c < acols - 1; c++) { + rc = &cols[c]; + + memcpy(orig, rc->rc_data, rc->rc_size); + + for (c1 = c + 1; c1 < acols; c1++) { + rc1 = &cols[c1]; + + memcpy(orig1, rc1->rc_data, rc1->rc_size); + + vdev_raidz_reconstruct_pq(cols, nparity, + acols, c, c1); + + if (zio_checksum_error(bp, buf) == 0) + return (0); + + memcpy(rc1->rc_data, orig1, rc1->rc_size); + } + + memcpy(rc->rc_data, orig, rc->rc_size); + } + } + + return (EIO); +} + |
