d/freebsd-dev
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
e2b84e0308
freebsd-dev/sys/cddl/boot/zfs/zfssubr.c

926 lines
25 KiB
C
Raw Blame History

/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2007 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
static uint64_t zfs_crc64_table[256];
static void
zfs_init_crc(void)
{
int i, j;
uint64_t *ct;
/*
* Calculate the crc64 table (used for the zap hash
* function).
*/
if (zfs_crc64_table[128] != ZFS_CRC64_POLY) {
memset(zfs_crc64_table, 0, sizeof(zfs_crc64_table));
for (i = 0; i < 256; i++)
for (ct = zfs_crc64_table + i, *ct = i, j = 8; j > 0; j--)
*ct = (*ct >> 1) ^ (-(*ct & 1) & ZFS_CRC64_POLY);
}
}
static void
zio_checksum_off(const void *buf, uint64_t size, zio_cksum_t *zcp)
{
ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);
}
/*
* Signature for checksum functions.
*/
typedef void zio_checksum_t(const void *data, uint64_t size, zio_cksum_t *zcp);
/*
* Information about each checksum function.
*/
typedef struct zio_checksum_info {
zio_checksum_t *ci_func[2]; /* checksum function for each byteorder */
int ci_correctable; /* number of correctable bits */
int ci_zbt; /* uses zio block tail? */
const char *ci_name; /* descriptive name */
} zio_checksum_info_t;
#include "fletcher.c"
#include "sha256.c"
static zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = {
{{NULL, NULL}, 0, 0, "inherit"},
{{NULL, NULL}, 0, 0, "on"},
{{zio_checksum_off, zio_checksum_off}, 0, 0, "off"},
{{zio_checksum_SHA256, NULL}, 1, 1, "label"},
{{zio_checksum_SHA256, NULL}, 1, 1, "gang_header"},
{{fletcher_2_native, NULL}, 0, 1, "zilog"},
{{fletcher_2_native, NULL}, 0, 0, "fletcher2"},
{{fletcher_4_native, NULL}, 1, 0, "fletcher4"},
{{zio_checksum_SHA256, NULL}, 1, 0, "SHA256"},
};
/*
* Common signature for all zio compress/decompress functions.
*/
typedef size_t zio_compress_func_t(void *src, void *dst,
size_t s_len, size_t d_len, int);
typedef int zio_decompress_func_t(void *src, void *dst,
size_t s_len, size_t d_len, int);
/*
* Information about each compression function.
*/
typedef struct zio_compress_info {
zio_compress_func_t *ci_compress; /* compression function */
zio_decompress_func_t *ci_decompress; /* decompression function */
int ci_level; /* level parameter */
const char *ci_name; /* algorithm name */
} zio_compress_info_t;
#include "lzjb.c"
/*
* Compression vectors.
*/
static zio_compress_info_t zio_compress_table[ZIO_COMPRESS_FUNCTIONS] = {
{NULL, NULL, 0, "inherit"},
{NULL, NULL, 0, "on"},
{NULL, NULL, 0, "uncompressed"},
{NULL, lzjb_decompress, 0, "lzjb"},
{NULL, NULL, 0, "empty"},
{NULL, NULL, 1, "gzip-1"},
{NULL, NULL, 2, "gzip-2"},
{NULL, NULL, 3, "gzip-3"},
{NULL, NULL, 4, "gzip-4"},
{NULL, NULL, 5, "gzip-5"},
{NULL, NULL, 6, "gzip-6"},
{NULL, NULL, 7, "gzip-7"},
{NULL, NULL, 8, "gzip-8"},
{NULL, NULL, 9, "gzip-9"},
};
static int
zio_checksum_error(const blkptr_t *bp, void *data)
{
zio_cksum_t zc = bp->blk_cksum;
unsigned int checksum = BP_GET_CHECKSUM(bp);
uint64_t size = BP_GET_PSIZE(bp);
zio_block_tail_t *zbt = (zio_block_tail_t *)((char *)data + size) - 1;
zio_checksum_info_t *ci = &zio_checksum_table[checksum];
zio_cksum_t actual_cksum, expected_cksum;
if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL)
return (EINVAL);
if (ci->ci_zbt) {
expected_cksum = zbt->zbt_cksum;
zbt->zbt_cksum = zc;
ci->ci_func[0](data, size, &actual_cksum);
zbt->zbt_cksum = expected_cksum;
zc = expected_cksum;
} else {
/* ASSERT(!BP_IS_GANG(bp)); */
ci->ci_func[0](data, size, &actual_cksum);
}
if (!ZIO_CHECKSUM_EQUAL(actual_cksum, zc)) {
/*printf("ZFS: read checksum failed\n");*/
return (EIO);
}
return (0);
}
static int
zio_decompress_data(int cpfunc, void *src, uint64_t srcsize,
void *dest, uint64_t destsize)
{
zio_compress_info_t *ci = &zio_compress_table[cpfunc];
/* ASSERT((uint_t)cpfunc < ZIO_COMPRESS_FUNCTIONS); */
if (!ci->ci_decompress) {
printf("ZFS: unsupported compression algorithm %u\n", cpfunc);
return (EIO);
}
return (ci->ci_decompress(src, dest, srcsize, destsize, ci->ci_level));
}
static uint64_t
zap_hash(uint64_t salt, const char *name)
{
const uint8_t *cp;
uint8_t c;
uint64_t crc = salt;
/*ASSERT(crc != 0);*/
/*ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY);*/
for (cp = (const uint8_t *)name; (c = *cp) != '\0'; cp++)
crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ c) & 0xFF];
/*
* Only use 28 bits, since we need 4 bits in the cookie for the
* collision differentiator. We MUST use the high bits, since
* those are the onces that we first pay attention to when
* chosing the bucket.
*/
crc &= ~((1ULL << (64 - ZAP_HASHBITS)) - 1);
return (crc);
}
static char *zfs_alloc_temp(size_t sz);
typedef struct raidz_col {
uint64_t rc_devidx; /* child device index for I/O */
uint64_t rc_offset; /* device offset */
uint64_t rc_size; /* I/O size */
void *rc_data; /* I/O data */
int rc_error; /* I/O error for this device */
uint8_t rc_tried; /* Did we attempt this I/O column? */
uint8_t rc_skipped; /* Did we skip this I/O column? */
} raidz_col_t;
#define VDEV_RAIDZ_P 0
#define VDEV_RAIDZ_Q 1
static void
vdev_raidz_reconstruct_p(raidz_col_t *cols, int nparity, int acols, int x)
{
uint64_t *dst, *src, xcount, ccount, count, i;
int c;
xcount = cols[x].rc_size / sizeof (src[0]);
//ASSERT(xcount <= cols[VDEV_RAIDZ_P].rc_size / sizeof (src[0]));
//ASSERT(xcount > 0);
src = cols[VDEV_RAIDZ_P].rc_data;
dst = cols[x].rc_data;
for (i = 0; i < xcount; i++, dst++, src++) {
*dst = *src;
}
for (c = nparity; c < acols; c++) {
src = cols[c].rc_data;
dst = cols[x].rc_data;
if (c == x)
continue;
ccount = cols[c].rc_size / sizeof (src[0]);
count = MIN(ccount, xcount);
for (i = 0; i < count; i++, dst++, src++) {
*dst ^= *src;
}
}
}
/*
* These two tables represent powers and logs of 2 in the Galois field defined
* above. These values were computed by repeatedly multiplying by 2 as above.
*/
static const uint8_t vdev_raidz_pow2[256] = {
0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80,
0x1d, 0x3a, 0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26,
0x4c, 0x98, 0x2d, 0x5a, 0xb4, 0x75, 0xea, 0xc9,
0x8f, 0x03, 0x06, 0x0c, 0x18, 0x30, 0x60, 0xc0,
0x9d, 0x27, 0x4e, 0x9c, 0x25, 0x4a, 0x94, 0x35,
0x6a, 0xd4, 0xb5, 0x77, 0xee, 0xc1, 0x9f, 0x23,
0x46, 0x8c, 0x05, 0x0a, 0x14, 0x28, 0x50, 0xa0,
0x5d, 0xba, 0x69, 0xd2, 0xb9, 0x6f, 0xde, 0xa1,
0x5f, 0xbe, 0x61, 0xc2, 0x99, 0x2f, 0x5e, 0xbc,
0x65, 0xca, 0x89, 0x0f, 0x1e, 0x3c, 0x78, 0xf0,
0xfd, 0xe7, 0xd3, 0xbb, 0x6b, 0xd6, 0xb1, 0x7f,
0xfe, 0xe1, 0xdf, 0xa3, 0x5b, 0xb6, 0x71, 0xe2,
0xd9, 0xaf, 0x43, 0x86, 0x11, 0x22, 0x44, 0x88,
0x0d, 0x1a, 0x34, 0x68, 0xd0, 0xbd, 0x67, 0xce,
0x81, 0x1f, 0x3e, 0x7c, 0xf8, 0xed, 0xc7, 0x93,
0x3b, 0x76, 0xec, 0xc5, 0x97, 0x33, 0x66, 0xcc,
0x85, 0x17, 0x2e, 0x5c, 0xb8, 0x6d, 0xda, 0xa9,
0x4f, 0x9e, 0x21, 0x42, 0x84, 0x15, 0x2a, 0x54,
0xa8, 0x4d, 0x9a, 0x29, 0x52, 0xa4, 0x55, 0xaa,
0x49, 0x92, 0x39, 0x72, 0xe4, 0xd5, 0xb7, 0x73,
0xe6, 0xd1, 0xbf, 0x63, 0xc6, 0x91, 0x3f, 0x7e,
0xfc, 0xe5, 0xd7, 0xb3, 0x7b, 0xf6, 0xf1, 0xff,
0xe3, 0xdb, 0xab, 0x4b, 0x96, 0x31, 0x62, 0xc4,
0x95, 0x37, 0x6e, 0xdc, 0xa5, 0x57, 0xae, 0x41,
0x82, 0x19, 0x32, 0x64, 0xc8, 0x8d, 0x07, 0x0e,
0x1c, 0x38, 0x70, 0xe0, 0xdd, 0xa7, 0x53, 0xa6,
0x51, 0xa2, 0x59, 0xb2, 0x79, 0xf2, 0xf9, 0xef,
0xc3, 0x9b, 0x2b, 0x56, 0xac, 0x45, 0x8a, 0x09,
0x12, 0x24, 0x48, 0x90, 0x3d, 0x7a, 0xf4, 0xf5,
0xf7, 0xf3, 0xfb, 0xeb, 0xcb, 0x8b, 0x0b, 0x16,
0x2c, 0x58, 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83,
0x1b, 0x36, 0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x01
};
static const uint8_t vdev_raidz_log2[256] = {
0x00, 0x00, 0x01, 0x19, 0x02, 0x32, 0x1a, 0xc6,
0x03, 0xdf, 0x33, 0xee, 0x1b, 0x68, 0xc7, 0x4b,
0x04, 0x64, 0xe0, 0x0e, 0x34, 0x8d, 0xef, 0x81,
0x1c, 0xc1, 0x69, 0xf8, 0xc8, 0x08, 0x4c, 0x71,
0x05, 0x8a, 0x65, 0x2f, 0xe1, 0x24, 0x0f, 0x21,
0x35, 0x93, 0x8e, 0xda, 0xf0, 0x12, 0x82, 0x45,
0x1d, 0xb5, 0xc2, 0x7d, 0x6a, 0x27, 0xf9, 0xb9,
0xc9, 0x9a, 0x09, 0x78, 0x4d, 0xe4, 0x72, 0xa6,
0x06, 0xbf, 0x8b, 0x62, 0x66, 0xdd, 0x30, 0xfd,
0xe2, 0x98, 0x25, 0xb3, 0x10, 0x91, 0x22, 0x88,
0x36, 0xd0, 0x94, 0xce, 0x8f, 0x96, 0xdb, 0xbd,
0xf1, 0xd2, 0x13, 0x5c, 0x83, 0x38, 0x46, 0x40,
0x1e, 0x42, 0xb6, 0xa3, 0xc3, 0x48, 0x7e, 0x6e,
0x6b, 0x3a, 0x28, 0x54, 0xfa, 0x85, 0xba, 0x3d,
0xca, 0x5e, 0x9b, 0x9f, 0x0a, 0x15, 0x79, 0x2b,
0x4e, 0xd4, 0xe5, 0xac, 0x73, 0xf3, 0xa7, 0x57,
0x07, 0x70, 0xc0, 0xf7, 0x8c, 0x80, 0x63, 0x0d,
0x67, 0x4a, 0xde, 0xed, 0x31, 0xc5, 0xfe, 0x18,
0xe3, 0xa5, 0x99, 0x77, 0x26, 0xb8, 0xb4, 0x7c,
0x11, 0x44, 0x92, 0xd9, 0x23, 0x20, 0x89, 0x2e,
0x37, 0x3f, 0xd1, 0x5b, 0x95, 0xbc, 0xcf, 0xcd,
0x90, 0x87, 0x97, 0xb2, 0xdc, 0xfc, 0xbe, 0x61,
0xf2, 0x56, 0xd3, 0xab, 0x14, 0x2a, 0x5d, 0x9e,
0x84, 0x3c, 0x39, 0x53, 0x47, 0x6d, 0x41, 0xa2,
0x1f, 0x2d, 0x43, 0xd8, 0xb7, 0x7b, 0xa4, 0x76,
0xc4, 0x17, 0x49, 0xec, 0x7f, 0x0c, 0x6f, 0xf6,
0x6c, 0xa1, 0x3b, 0x52, 0x29, 0x9d, 0x55, 0xaa,
0xfb, 0x60, 0x86, 0xb1, 0xbb, 0xcc, 0x3e, 0x5a,
0xcb, 0x59, 0x5f, 0xb0, 0x9c, 0xa9, 0xa0, 0x51,
0x0b, 0xf5, 0x16, 0xeb, 0x7a, 0x75, 0x2c, 0xd7,
0x4f, 0xae, 0xd5, 0xe9, 0xe6, 0xe7, 0xad, 0xe8,
0x74, 0xd6, 0xf4, 0xea, 0xa8, 0x50, 0x58, 0xaf,
};
/*
* Multiply a given number by 2 raised to the given power.
*/
static uint8_t
vdev_raidz_exp2(uint8_t a, int exp)
{
if (a == 0)
return (0);
//ASSERT(exp >= 0);
//ASSERT(vdev_raidz_log2[a] > 0 || a == 1);
exp += vdev_raidz_log2[a];
if (exp > 255)
exp -= 255;
return (vdev_raidz_pow2[exp]);
}
static void
vdev_raidz_generate_parity_pq(raidz_col_t *cols, int nparity, int acols)
{
uint64_t *q, *p, *src, pcount, ccount, mask, i;
int c;
pcount = cols[VDEV_RAIDZ_P].rc_size / sizeof (src[0]);
//ASSERT(cols[VDEV_RAIDZ_P].rc_size == cols[VDEV_RAIDZ_Q].rc_size);
for (c = nparity; c < acols; c++) {
src = cols[c].rc_data;
p = cols[VDEV_RAIDZ_P].rc_data;
q = cols[VDEV_RAIDZ_Q].rc_data;
ccount = cols[c].rc_size / sizeof (src[0]);
if (c == nparity) {
//ASSERT(ccount == pcount || ccount == 0);
for (i = 0; i < ccount; i++, p++, q++, src++) {
*q = *src;
*p = *src;
}
for (; i < pcount; i++, p++, q++, src++) {
*q = 0;
*p = 0;
}
} else {
//ASSERT(ccount <= pcount);
/*
* Rather than multiplying each byte
* individually (as described above), we are
* able to handle 8 at once by generating a
* mask based on the high bit in each byte and
* using that to conditionally XOR in 0x1d.
*/
for (i = 0; i < ccount; i++, p++, q++, src++) {
mask = *q & 0x8080808080808080ULL;
mask = (mask << 1) - (mask >> 7);
*q = ((*q << 1) & 0xfefefefefefefefeULL) ^
(mask & 0x1d1d1d1d1d1d1d1dULL);
*q ^= *src;
*p ^= *src;
}
/*
* Treat short columns as though they are full of 0s.
*/
for (; i < pcount; i++, q++) {
mask = *q & 0x8080808080808080ULL;
mask = (mask << 1) - (mask >> 7);
*q = ((*q << 1) & 0xfefefefefefefefeULL) ^
(mask & 0x1d1d1d1d1d1d1d1dULL);
}
}
}
}
static void
vdev_raidz_reconstruct_q(raidz_col_t *cols, int nparity, int acols, int x)
{
uint64_t *dst, *src, xcount, ccount, count, mask, i;
uint8_t *b;
int c, j, exp;
xcount = cols[x].rc_size / sizeof (src[0]);
//ASSERT(xcount <= cols[VDEV_RAIDZ_Q].rc_size / sizeof (src[0]));
for (c = nparity; c < acols; c++) {
src = cols[c].rc_data;
dst = cols[x].rc_data;
if (c == x)
ccount = 0;
else
ccount = cols[c].rc_size / sizeof (src[0]);
count = MIN(ccount, xcount);
if (c == nparity) {
for (i = 0; i < count; i++, dst++, src++) {
*dst = *src;
}
for (; i < xcount; i++, dst++) {
*dst = 0;
}
} else {
/*
* For an explanation of this, see the comment in
* vdev_raidz_generate_parity_pq() above.
*/
for (i = 0; i < count; i++, dst++, src++) {
mask = *dst & 0x8080808080808080ULL;
mask = (mask << 1) - (mask >> 7);
*dst = ((*dst << 1) & 0xfefefefefefefefeULL) ^
(mask & 0x1d1d1d1d1d1d1d1dULL);
*dst ^= *src;
}
for (; i < xcount; i++, dst++) {
mask = *dst & 0x8080808080808080ULL;
mask = (mask << 1) - (mask >> 7);
*dst = ((*dst << 1) & 0xfefefefefefefefeULL) ^
(mask & 0x1d1d1d1d1d1d1d1dULL);
}
}
}
src = cols[VDEV_RAIDZ_Q].rc_data;
dst = cols[x].rc_data;
exp = 255 - (acols - 1 - x);
for (i = 0; i < xcount; i++, dst++, src++) {
*dst ^= *src;
for (j = 0, b = (uint8_t *)dst; j < 8; j++, b++) {
*b = vdev_raidz_exp2(*b, exp);
}
}
}
static void
vdev_raidz_reconstruct_pq(raidz_col_t *cols, int nparity, int acols,
int x, int y)
{
uint8_t *p, *q, *pxy, *qxy, *xd, *yd, tmp, a, b, aexp, bexp;
void *pdata, *qdata;
uint64_t xsize, ysize, i;
//ASSERT(x < y);
//ASSERT(x >= nparity);
//ASSERT(y < acols);
//ASSERT(cols[x].rc_size >= cols[y].rc_size);
/*
* Move the parity data aside -- we're going to compute parity as
* though columns x and y were full of zeros -- Pxy and Qxy. We want to
* reuse the parity generation mechanism without trashing the actual
* parity so we make those columns appear to be full of zeros by
* setting their lengths to zero.
*/
pdata = cols[VDEV_RAIDZ_P].rc_data;
qdata = cols[VDEV_RAIDZ_Q].rc_data;
xsize = cols[x].rc_size;
ysize = cols[y].rc_size;
cols[VDEV_RAIDZ_P].rc_data =
zfs_alloc_temp(cols[VDEV_RAIDZ_P].rc_size);
cols[VDEV_RAIDZ_Q].rc_data =
zfs_alloc_temp(cols[VDEV_RAIDZ_Q].rc_size);
cols[x].rc_size = 0;
cols[y].rc_size = 0;
vdev_raidz_generate_parity_pq(cols, nparity, acols);
cols[x].rc_size = xsize;
cols[y].rc_size = ysize;
p = pdata;
q = qdata;
pxy = cols[VDEV_RAIDZ_P].rc_data;
qxy = cols[VDEV_RAIDZ_Q].rc_data;
xd = cols[x].rc_data;
yd = cols[y].rc_data;
/*
* We now have:
* Pxy = P + D_x + D_y
* Qxy = Q + 2^(ndevs - 1 - x) * D_x + 2^(ndevs - 1 - y) * D_y
*
* We can then solve for D_x:
* D_x = A * (P + Pxy) + B * (Q + Qxy)
* where
* A = 2^(x - y) * (2^(x - y) + 1)^-1
* B = 2^(ndevs - 1 - x) * (2^(x - y) + 1)^-1
*
* With D_x in hand, we can easily solve for D_y:
* D_y = P + Pxy + D_x
*/
a = vdev_raidz_pow2[255 + x - y];
b = vdev_raidz_pow2[255 - (acols - 1 - x)];
tmp = 255 - vdev_raidz_log2[a ^ 1];
aexp = vdev_raidz_log2[vdev_raidz_exp2(a, tmp)];
bexp = vdev_raidz_log2[vdev_raidz_exp2(b, tmp)];
for (i = 0; i < xsize; i++, p++, q++, pxy++, qxy++, xd++, yd++) {
*xd = vdev_raidz_exp2(*p ^ *pxy, aexp) ^
vdev_raidz_exp2(*q ^ *qxy, bexp);
if (i < ysize)
*yd = *p ^ *pxy ^ *xd;
}
/*
* Restore the saved parity data.
*/
cols[VDEV_RAIDZ_P].rc_data = pdata;
cols[VDEV_RAIDZ_Q].rc_data = qdata;
}
static int
vdev_raidz_read(vdev_t *vdev, const blkptr_t *bp, void *buf,
off_t offset, size_t bytes)
{
size_t psize = BP_GET_PSIZE(bp);
vdev_t *kid;
int unit_shift = vdev->v_ashift;
int dcols = vdev->v_nchildren;
int nparity = vdev->v_nparity;
int missingdata, missingparity;
int parity_errors, data_errors, unexpected_errors, total_errors;
int parity_untried;
uint64_t b = offset >> unit_shift;
uint64_t s = psize >> unit_shift;
uint64_t f = b % dcols;
uint64_t o = (b / dcols) << unit_shift;
int q, r, c, c1, bc, col, acols, coff, devidx, asize, n;
static raidz_col_t cols[16];
raidz_col_t *rc, *rc1;
q = s / (dcols - nparity);
r = s - q * (dcols - nparity);
bc = (r == 0 ? 0 : r + nparity);
acols = (q == 0 ? bc : dcols);
asize = 0;
for (c = 0; c < acols; c++) {
col = f + c;
coff = o;
if (col >= dcols) {
col -= dcols;
coff += 1ULL << unit_shift;
}
cols[c].rc_devidx = col;
cols[c].rc_offset = coff;
cols[c].rc_size = (q + (c < bc)) << unit_shift;
cols[c].rc_data = NULL;
cols[c].rc_error = 0;
cols[c].rc_tried = 0;
cols[c].rc_skipped = 0;
asize += cols[c].rc_size;
}
asize = roundup(asize, (nparity + 1) << unit_shift);
for (c = 0; c < nparity; c++) {
cols[c].rc_data = zfs_alloc_temp(cols[c].rc_size);
}
cols[c].rc_data = buf;
for (c = c + 1; c < acols; c++)
cols[c].rc_data = (char *)cols[c - 1].rc_data +
cols[c - 1].rc_size;
/*
* If all data stored spans all columns, there's a danger that
* parity will always be on the same device and, since parity
* isn't read during normal operation, that that device's I/O
* bandwidth won't be used effectively. We therefore switch
* the parity every 1MB.
*
* ... at least that was, ostensibly, the theory. As a
* practical matter unless we juggle the parity between all
* devices evenly, we won't see any benefit. Further,
* occasional writes that aren't a multiple of the LCM of the
* number of children and the minimum stripe width are
* sufficient to avoid pessimal behavior. Unfortunately, this
* decision created an implicit on-disk format requirement
* that we need to support for all eternity, but only for
* single-parity RAID-Z.
*/
//ASSERT(acols >= 2);
//ASSERT(cols[0].rc_size == cols[1].rc_size);
if (nparity == 1 && (offset & (1ULL << 20))) {
devidx = cols[0].rc_devidx;
o = cols[0].rc_offset;
cols[0].rc_devidx = cols[1].rc_devidx;
cols[0].rc_offset = cols[1].rc_offset;
cols[1].rc_devidx = devidx;
cols[1].rc_offset = o;
}
/*
* Iterate over the columns in reverse order so that we hit
* the parity last -- any errors along the way will force us
* to read the parity data.
*/
missingdata = 0;
missingparity = 0;
for (c = acols - 1; c >= 0; c--) {
rc = &cols[c];
devidx = rc->rc_devidx;
STAILQ_FOREACH(kid, &vdev->v_children, v_childlink)
if (kid->v_id == devidx)
break;
if (kid == NULL || kid->v_state != VDEV_STATE_HEALTHY) {
if (c >= nparity)
missingdata++;
else
missingparity++;
rc->rc_error = ENXIO;
rc->rc_tried = 1; /* don't even try */
rc->rc_skipped = 1;
continue;
}
#if 0
/*
* Too hard for the bootcode
*/
if (vdev_dtl_contains(&cvd->vdev_dtl_map, bp->blk_birth, 1)) {
if (c >= nparity)
rm->rm_missingdata++;
else
rm->rm_missingparity++;
rc->rc_error = ESTALE;
rc->rc_skipped = 1;
continue;
}
#endif
if (c >= nparity || missingdata > 0) {
if (rc->rc_data)
rc->rc_error = kid->v_read(kid, NULL,
rc->rc_data, rc->rc_offset, rc->rc_size);
else
rc->rc_error = ENXIO;
rc->rc_tried = 1;
rc->rc_skipped = 0;
}
}
reconstruct:
parity_errors = 0;
data_errors = 0;
unexpected_errors = 0;
total_errors = 0;
parity_untried = 0;
for (c = 0; c < acols; c++) {
rc = &cols[c];
if (rc->rc_error) {
if (c < nparity)
parity_errors++;
else
data_errors++;
if (!rc->rc_skipped)
unexpected_errors++;
total_errors++;
} else if (c < nparity && !rc->rc_tried) {
parity_untried++;
}
}
/*
* There are three potential phases for a read:
* 1. produce valid data from the columns read
* 2. read all disks and try again
* 3. perform combinatorial reconstruction
*
* Each phase is progressively both more expensive and less
* likely to occur. If we encounter more errors than we can
* repair or all phases fail, we have no choice but to return
* an error.
*/
/*
* If the number of errors we saw was correctable -- less than
* or equal to the number of parity disks read -- attempt to
* produce data that has a valid checksum. Naturally, this
* case applies in the absence of any errors.
*/
if (total_errors <= nparity - parity_untried) {
switch (data_errors) {
case 0:
if (zio_checksum_error(bp, buf) == 0)
return (0);
break;
case 1:
/*
* We either attempt to read all the parity columns or
* none of them. If we didn't try to read parity, we
* wouldn't be here in the correctable case. There must
* also have been fewer parity errors than parity
* columns or, again, we wouldn't be in this code path.
*/
//ASSERT(parity_untried == 0);
//ASSERT(parity_errors < nparity);
/*
* Find the column that reported the error.
*/
for (c = nparity; c < acols; c++) {
rc = &cols[c];
if (rc->rc_error != 0)
break;
}
//ASSERT(c != acols);
//ASSERT(!rc->rc_skipped || rc->rc_error == ENXIO || rc->rc_error == ESTALE);
if (cols[VDEV_RAIDZ_P].rc_error == 0) {
vdev_raidz_reconstruct_p(cols, nparity,
acols, c);
} else {
//ASSERT(nparity > 1);
vdev_raidz_reconstruct_q(cols, nparity,
acols, c);
}
if (zio_checksum_error(bp, buf) == 0)
return (0);
break;
case 2:
/*
* Two data column errors require double parity.
*/
//ASSERT(nparity == 2);
/*
* Find the two columns that reported errors.
*/
for (c = nparity; c < acols; c++) {
rc = &cols[c];
if (rc->rc_error != 0)
break;
}
//ASSERT(c != acols);
//ASSERT(!rc->rc_skipped || rc->rc_error == ENXIO || rc->rc_error == ESTALE);
for (c1 = c++; c < acols; c++) {
rc = &cols[c];
if (rc->rc_error != 0)
break;
}
//ASSERT(c != acols);
//ASSERT(!rc->rc_skipped || rc->rc_error == ENXIO || rc->rc_error == ESTALE);
vdev_raidz_reconstruct_pq(cols, nparity, acols,
c1, c);
if (zio_checksum_error(bp, buf) == 0)
return (0);
break;
default:
break;
//ASSERT(nparity <= 2);
//ASSERT(0);
}
}
/*
* This isn't a typical situation -- either we got a read
* error or a child silently returned bad data. Read every
* block so we can try again with as much data and parity as
* we can track down. If we've already been through once
* before, all children will be marked as tried so we'll
* proceed to combinatorial reconstruction.
*/
n = 0;
for (c = 0; c < acols; c++) {
rc = &cols[c];
if (rc->rc_tried)
continue;
devidx = rc->rc_devidx;
STAILQ_FOREACH(kid, &vdev->v_children, v_childlink)
if (kid->v_id == devidx)
break;
if (kid == NULL || kid->v_state != VDEV_STATE_HEALTHY) {
rc->rc_error = ENXIO;
rc->rc_tried = 1; /* don't even try */
rc->rc_skipped = 1;
continue;
}
if (rc->rc_data)
rc->rc_error = kid->v_read(kid, NULL,
rc->rc_data, rc->rc_offset, rc->rc_size);
else
rc->rc_error = ENXIO;
if (rc->rc_error == 0)
n++;
rc->rc_tried = 1;
rc->rc_skipped = 0;
}
/*
* If we managed to read anything more, retry the
* reconstruction.
*/
if (n)
goto reconstruct;
/*
* At this point we've attempted to reconstruct the data given the
* errors we detected, and we've attempted to read all columns. There
* must, therefore, be one or more additional problems -- silent errors
* resulting in invalid data rather than explicit I/O errors resulting
* in absent data. Before we attempt combinatorial reconstruction make
* sure we have a chance of coming up with the right answer.
*/
if (total_errors >= nparity) {
return (EIO);
}
asize = 0;
for (c = 0; c < acols; c++) {
rc = &cols[c];
if (rc->rc_size > asize)
asize = rc->rc_size;
}
if (cols[VDEV_RAIDZ_P].rc_error == 0) {
/*
* Attempt to reconstruct the data from parity P.
*/
void *orig;
orig = zfs_alloc_temp(asize);
for (c = nparity; c < acols; c++) {
rc = &cols[c];
memcpy(orig, rc->rc_data, rc->rc_size);
vdev_raidz_reconstruct_p(cols, nparity, acols, c);
if (zio_checksum_error(bp, buf) == 0)
return (0);
memcpy(rc->rc_data, orig, rc->rc_size);
}
}
if (nparity > 1 && cols[VDEV_RAIDZ_Q].rc_error == 0) {
/*
* Attempt to reconstruct the data from parity Q.
*/
void *orig;
orig = zfs_alloc_temp(asize);
for (c = nparity; c < acols; c++) {
rc = &cols[c];
memcpy(orig, rc->rc_data, rc->rc_size);
vdev_raidz_reconstruct_q(cols, nparity, acols, c);
if (zio_checksum_error(bp, buf) == 0)
return (0);
memcpy(rc->rc_data, orig, rc->rc_size);
}
}
if (nparity > 1 &&
cols[VDEV_RAIDZ_P].rc_error == 0 &&
cols[VDEV_RAIDZ_Q].rc_error == 0) {
/*
* Attempt to reconstruct the data from both P and Q.
*/
void *orig, *orig1;
orig = zfs_alloc_temp(asize);
orig1 = zfs_alloc_temp(asize);
for (c = nparity; c < acols - 1; c++) {
rc = &cols[c];
memcpy(orig, rc->rc_data, rc->rc_size);
for (c1 = c + 1; c1 < acols; c1++) {
rc1 = &cols[c1];
memcpy(orig1, rc1->rc_data, rc1->rc_size);
vdev_raidz_reconstruct_pq(cols, nparity,
acols, c, c1);
if (zio_checksum_error(bp, buf) == 0)
return (0);
memcpy(rc1->rc_data, orig1, rc1->rc_size);
}
memcpy(rc->rc_data, orig, rc->rc_size);
}
}
return (EIO);
}
Reference in New Issue View Git Blame Copy Permalink