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mirror_zfs/module/zfs/vdev_raidz.c
Brian Atkinson 345196be18
Single IO issue for raidz writes with skip sector 
In order to reduce contention on the vq_lock, optional skip sectors
for Raidz writes can be placed into a single IO request. This is done by
padding out the linear ABD for a parity column to contain the skip
sector and by creating gang ABD to contain the data and skip sector for
data columns.

The vdev_raidz_map_alloc() function now contains specific functions for
both reads and write to allocate the ABD's that will be issued down to
the VDEV chldren.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-By: Mark Maybee <mark.maybee@delphix.com>
Signed-off-by: Brian Atkinson <batkinson@lanl.gov>
Closes #12333
2021-11-09 12:51:33 -07:00

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/*
* 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, 2020 by Delphix. All rights reserved.
* Copyright (c) 2016 Gvozden Nešković. All rights reserved.
*/
#include <sys/zfs_context.h>
#include <sys/spa.h>
#include <sys/vdev_impl.h>
#include <sys/zio.h>
#include <sys/zio_checksum.h>
#include <sys/abd.h>
#include <sys/fs/zfs.h>
#include <sys/fm/fs/zfs.h>
#include <sys/vdev_raidz.h>
#include <sys/vdev_raidz_impl.h>
#include <sys/vdev_draid.h>
#ifdef ZFS_DEBUG
#include <sys/vdev.h> /* For vdev_xlate() in vdev_raidz_io_verify() */
#endif
/*
* Virtual device vector for RAID-Z.
*
* This vdev supports single, double, and triple parity. For single parity,
* we use a simple XOR of all the data columns. For double or triple parity,
* we use a special case of Reed-Solomon coding. This extends the
* technique described in "The mathematics of RAID-6" by H. Peter Anvin by
* drawing on the system described in "A Tutorial on Reed-Solomon Coding for
* Fault-Tolerance in RAID-like Systems" by James S. Plank on which the
* former is also based. The latter is designed to provide higher performance
* for writes.
*
* Note that the Plank paper claimed to support arbitrary N+M, but was then
* amended six years later identifying a critical flaw that invalidates its
* claims. Nevertheless, the technique can be adapted to work for up to
* triple parity. For additional parity, the amendment "Note: Correction to
* the 1997 Tutorial on Reed-Solomon Coding" by James S. Plank and Ying Ding
* is viable, but the additional complexity means that write performance will
* suffer.
*
* All of the methods above operate on a Galois field, defined over the
* integers mod 2^N. In our case we choose N=8 for GF(8) so that all elements
* can be expressed with a single byte. Briefly, the operations on the
* field are defined as follows:
*
* o addition (+) is represented by a bitwise XOR
* o subtraction (-) is therefore identical to addition: A + B = A - B
* o multiplication of A by 2 is defined by the following bitwise expression:
*
* (A * 2)_7 = A_6
* (A * 2)_6 = A_5
* (A * 2)_5 = A_4
* (A * 2)_4 = A_3 + A_7
* (A * 2)_3 = A_2 + A_7
* (A * 2)_2 = A_1 + A_7
* (A * 2)_1 = A_0
* (A * 2)_0 = A_7
*
* In C, multiplying by 2 is therefore ((a << 1) ^ ((a & 0x80) ? 0x1d : 0)).
* As an aside, this multiplication is derived from the error correcting
* primitive polynomial x^8 + x^4 + x^3 + x^2 + 1.
*
* Observe that any number in the field (except for 0) can be expressed as a
* power of 2 -- a generator for the field. We store a table of the powers of
* 2 and logs base 2 for quick look ups, and exploit the fact that A * B can
* be rewritten as 2^(log_2(A) + log_2(B)) (where '+' is normal addition rather
* than field addition). The inverse of a field element A (A^-1) is therefore
* A ^ (255 - 1) = A^254.
*
* The up-to-three parity columns, P, Q, R over several data columns,
* D_0, ... D_n-1, can be expressed by field operations:
*
* P = D_0 + D_1 + ... + D_n-2 + D_n-1
* Q = 2^n-1 * D_0 + 2^n-2 * D_1 + ... + 2^1 * D_n-2 + 2^0 * D_n-1
* = ((...((D_0) * 2 + D_1) * 2 + ...) * 2 + D_n-2) * 2 + D_n-1
* R = 4^n-1 * D_0 + 4^n-2 * D_1 + ... + 4^1 * D_n-2 + 4^0 * D_n-1
* = ((...((D_0) * 4 + D_1) * 4 + ...) * 4 + D_n-2) * 4 + D_n-1
*
* We chose 1, 2, and 4 as our generators because 1 corresponds to the trivial
* XOR operation, and 2 and 4 can be computed quickly and generate linearly-
* independent coefficients. (There are no additional coefficients that have
* this property which is why the uncorrected Plank method breaks down.)
*
* See the reconstruction code below for how P, Q and R can used individually
* or in concert to recover missing data columns.
*/
#define VDEV_RAIDZ_P 0
#define VDEV_RAIDZ_Q 1
#define VDEV_RAIDZ_R 2
#define VDEV_RAIDZ_MUL_2(x) (((x) << 1) ^ (((x) & 0x80) ? 0x1d : 0))
#define VDEV_RAIDZ_MUL_4(x) (VDEV_RAIDZ_MUL_2(VDEV_RAIDZ_MUL_2(x)))
/*
* We provide a mechanism to perform the field multiplication operation on a
* 64-bit value all at once rather than a byte at a time. This works by
* creating a mask from the top bit in each byte and using that to
* conditionally apply the XOR of 0x1d.
*/
#define VDEV_RAIDZ_64MUL_2(x, mask) \
{ \
(mask) = (x) & 0x8080808080808080ULL; \
(mask) = ((mask) << 1) - ((mask) >> 7); \
(x) = (((x) << 1) & 0xfefefefefefefefeULL) ^ \
((mask) & 0x1d1d1d1d1d1d1d1dULL); \
}
#define VDEV_RAIDZ_64MUL_4(x, mask) \
{ \
VDEV_RAIDZ_64MUL_2((x), mask); \
VDEV_RAIDZ_64MUL_2((x), mask); \
}
static void
vdev_raidz_row_free(raidz_row_t *rr)
{
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_size != 0)
abd_free(rc->rc_abd);
if (rc->rc_orig_data != NULL)
abd_free(rc->rc_orig_data);
}
if (rr->rr_abd_empty != NULL)
abd_free(rr->rr_abd_empty);
kmem_free(rr, offsetof(raidz_row_t, rr_col[rr->rr_scols]));
}
void
vdev_raidz_map_free(raidz_map_t *rm)
{
for (int i = 0; i < rm->rm_nrows; i++)
vdev_raidz_row_free(rm->rm_row[i]);
kmem_free(rm, offsetof(raidz_map_t, rm_row[rm->rm_nrows]));
}
static void
vdev_raidz_map_free_vsd(zio_t *zio)
{
raidz_map_t *rm = zio->io_vsd;
vdev_raidz_map_free(rm);
}
const zio_vsd_ops_t vdev_raidz_vsd_ops = {
.vsd_free = vdev_raidz_map_free_vsd,
};
static void
vdev_raidz_map_alloc_write(zio_t *zio, raidz_map_t *rm, uint64_t ashift)
{
int c;
int nwrapped = 0;
uint64_t off = 0;
raidz_row_t *rr = rm->rm_row[0];
ASSERT3U(zio->io_type, ==, ZIO_TYPE_WRITE);
ASSERT3U(rm->rm_nrows, ==, 1);
/*
* Pad any parity columns with additional space to account for skip
* sectors.
*/
if (rm->rm_skipstart < rr->rr_firstdatacol) {
ASSERT0(rm->rm_skipstart);
nwrapped = rm->rm_nskip;
} else if (rr->rr_scols < (rm->rm_skipstart + rm->rm_nskip)) {
nwrapped =
(rm->rm_skipstart + rm->rm_nskip) % rr->rr_scols;
}
/*
* Optional single skip sectors (rc_size == 0) will be handled in
* vdev_raidz_io_start_write().
*/
int skipped = rr->rr_scols - rr->rr_cols;
/* Allocate buffers for the parity columns */
for (c = 0; c < rr->rr_firstdatacol; c++) {
raidz_col_t *rc = &rr->rr_col[c];
/*
* Parity columns will pad out a linear ABD to account for
* the skip sector. A linear ABD is used here because
* parity calculations use the ABD buffer directly to calculate
* parity. This avoids doing a memcpy back to the ABD after the
* parity has been calculated. By issuing the parity column
* with the skip sector we can reduce contention on the child
* VDEV queue locks (vq_lock).
*/
if (c < nwrapped) {
rc->rc_abd = abd_alloc_linear(
rc->rc_size + (1ULL << ashift), B_FALSE);
abd_zero_off(rc->rc_abd, rc->rc_size, 1ULL << ashift);
skipped++;
} else {
rc->rc_abd = abd_alloc_linear(rc->rc_size, B_FALSE);
}
}
for (off = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
abd_t *abd = abd_get_offset_struct(&rc->rc_abdstruct,
zio->io_abd, off, rc->rc_size);
/*
* Generate I/O for skip sectors to improve aggregation
* continuity. We will use gang ABD's to reduce contention
* on the child VDEV queue locks (vq_lock) by issuing
* a single I/O that contains the data and skip sector.
*
* It is important to make sure that rc_size is not updated
* even though we are adding a skip sector to the ABD. When
* calculating the parity in vdev_raidz_generate_parity_row()
* the rc_size is used to iterate through the ABD's. We can
* not have zero'd out skip sectors used for calculating
* parity for raidz, because those same sectors are not used
* during reconstruction.
*/
if (c >= rm->rm_skipstart && skipped < rm->rm_nskip) {
rc->rc_abd = abd_alloc_gang();
abd_gang_add(rc->rc_abd, abd, B_TRUE);
abd_gang_add(rc->rc_abd,
abd_get_zeros(1ULL << ashift), B_TRUE);
skipped++;
} else {
rc->rc_abd = abd;
}
off += rc->rc_size;
}
ASSERT3U(off, ==, zio->io_size);
ASSERT3S(skipped, ==, rm->rm_nskip);
}
static void
vdev_raidz_map_alloc_read(zio_t *zio, raidz_map_t *rm)
{
int c;
raidz_row_t *rr = rm->rm_row[0];
ASSERT3U(rm->rm_nrows, ==, 1);
/* Allocate buffers for the parity columns */
for (c = 0; c < rr->rr_firstdatacol; c++)
rr->rr_col[c].rc_abd =
abd_alloc_linear(rr->rr_col[c].rc_size, B_FALSE);
for (uint64_t off = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
rc->rc_abd = abd_get_offset_struct(&rc->rc_abdstruct,
zio->io_abd, off, rc->rc_size);
off += rc->rc_size;
}
}
/*
* Divides the IO evenly across all child vdevs; usually, dcols is
* the number of children in the target vdev.
*
* Avoid inlining the function to keep vdev_raidz_io_start(), which
* is this functions only caller, as small as possible on the stack.
*/
noinline raidz_map_t *
vdev_raidz_map_alloc(zio_t *zio, uint64_t ashift, uint64_t dcols,
uint64_t nparity)
{
raidz_row_t *rr;
/* The starting RAIDZ (parent) vdev sector of the block. */
uint64_t b = zio->io_offset >> ashift;
/* The zio's size in units of the vdev's minimum sector size. */
uint64_t s = zio->io_size >> ashift;
/* The first column for this stripe. */
uint64_t f = b % dcols;
/* The starting byte offset on each child vdev. */
uint64_t o = (b / dcols) << ashift;
uint64_t q, r, c, bc, col, acols, scols, coff, devidx, asize, tot;
raidz_map_t *rm =
kmem_zalloc(offsetof(raidz_map_t, rm_row[1]), KM_SLEEP);
rm->rm_nrows = 1;
/*
* "Quotient": The number of data sectors for this stripe on all but
* the "big column" child vdevs that also contain "remainder" data.
*/
q = s / (dcols - nparity);
/*
* "Remainder": The number of partial stripe data sectors in this I/O.
* This will add a sector to some, but not all, child vdevs.
*/
r = s - q * (dcols - nparity);
/* The number of "big columns" - those which contain remainder data. */
bc = (r == 0 ? 0 : r + nparity);
/*
* The total number of data and parity sectors associated with
* this I/O.
*/
tot = s + nparity * (q + (r == 0 ? 0 : 1));
/*
* acols: The columns that will be accessed.
* scols: The columns that will be accessed or skipped.
*/
if (q == 0) {
/* Our I/O request doesn't span all child vdevs. */
acols = bc;
scols = MIN(dcols, roundup(bc, nparity + 1));
} else {
acols = dcols;
scols = dcols;
}
ASSERT3U(acols, <=, scols);
rr = kmem_alloc(offsetof(raidz_row_t, rr_col[scols]), KM_SLEEP);
rm->rm_row[0] = rr;
rr->rr_cols = acols;
rr->rr_scols = scols;
rr->rr_bigcols = bc;
rr->rr_missingdata = 0;
rr->rr_missingparity = 0;
rr->rr_firstdatacol = nparity;
rr->rr_abd_empty = NULL;
rr->rr_nempty = 0;
#ifdef ZFS_DEBUG
rr->rr_offset = zio->io_offset;
rr->rr_size = zio->io_size;
#endif
asize = 0;
for (c = 0; c < scols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
col = f + c;
coff = o;
if (col >= dcols) {
col -= dcols;
coff += 1ULL << ashift;
}
rc->rc_devidx = col;
rc->rc_offset = coff;
rc->rc_abd = NULL;
rc->rc_orig_data = NULL;
rc->rc_error = 0;
rc->rc_tried = 0;
rc->rc_skipped = 0;
rc->rc_force_repair = 0;
rc->rc_allow_repair = 1;
rc->rc_need_orig_restore = B_FALSE;
if (c >= acols)
rc->rc_size = 0;
else if (c < bc)
rc->rc_size = (q + 1) << ashift;
else
rc->rc_size = q << ashift;
asize += rc->rc_size;
}
ASSERT3U(asize, ==, tot << ashift);
rm->rm_nskip = roundup(tot, nparity + 1) - tot;
rm->rm_skipstart = bc;
/*
* If all data stored spans all columns, there's a danger that parity
* will always be on the same device and, since parity isn't read
* during normal operation, that device's I/O bandwidth won't be
* used effectively. We therefore switch the parity every 1MB.
*
* ... at least that was, ostensibly, the theory. As a practical
* matter unless we juggle the parity between all devices evenly, we
* won't see any benefit. Further, occasional writes that aren't a
* multiple of the LCM of the number of children and the minimum
* stripe width are sufficient to avoid pessimal behavior.
* Unfortunately, this decision created an implicit on-disk format
* requirement that we need to support for all eternity, but only
* for single-parity RAID-Z.
*
* If we intend to skip a sector in the zeroth column for padding
* we must make sure to note this swap. We will never intend to
* skip the first column since at least one data and one parity
* column must appear in each row.
*/
ASSERT(rr->rr_cols >= 2);
ASSERT(rr->rr_col[0].rc_size == rr->rr_col[1].rc_size);
if (rr->rr_firstdatacol == 1 && (zio->io_offset & (1ULL << 20))) {
devidx = rr->rr_col[0].rc_devidx;
o = rr->rr_col[0].rc_offset;
rr->rr_col[0].rc_devidx = rr->rr_col[1].rc_devidx;
rr->rr_col[0].rc_offset = rr->rr_col[1].rc_offset;
rr->rr_col[1].rc_devidx = devidx;
rr->rr_col[1].rc_offset = o;
if (rm->rm_skipstart == 0)
rm->rm_skipstart = 1;
}
if (zio->io_type == ZIO_TYPE_WRITE) {
vdev_raidz_map_alloc_write(zio, rm, ashift);
} else {
vdev_raidz_map_alloc_read(zio, rm);
}
/* init RAIDZ parity ops */
rm->rm_ops = vdev_raidz_math_get_ops();
return (rm);
}
struct pqr_struct {
uint64_t *p;
uint64_t *q;
uint64_t *r;
};
static int
vdev_raidz_p_func(void *buf, size_t size, void *private)
{
struct pqr_struct *pqr = private;
const uint64_t *src = buf;
int i, cnt = size / sizeof (src[0]);
ASSERT(pqr->p && !pqr->q && !pqr->r);
for (i = 0; i < cnt; i++, src++, pqr->p++)
*pqr->p ^= *src;
return (0);
}
static int
vdev_raidz_pq_func(void *buf, size_t size, void *private)
{
struct pqr_struct *pqr = private;
const uint64_t *src = buf;
uint64_t mask;
int i, cnt = size / sizeof (src[0]);
ASSERT(pqr->p && pqr->q && !pqr->r);
for (i = 0; i < cnt; i++, src++, pqr->p++, pqr->q++) {
*pqr->p ^= *src;
VDEV_RAIDZ_64MUL_2(*pqr->q, mask);
*pqr->q ^= *src;
}
return (0);
}
static int
vdev_raidz_pqr_func(void *buf, size_t size, void *private)
{
struct pqr_struct *pqr = private;
const uint64_t *src = buf;
uint64_t mask;
int i, cnt = size / sizeof (src[0]);
ASSERT(pqr->p && pqr->q && pqr->r);
for (i = 0; i < cnt; i++, src++, pqr->p++, pqr->q++, pqr->r++) {
*pqr->p ^= *src;
VDEV_RAIDZ_64MUL_2(*pqr->q, mask);
*pqr->q ^= *src;
VDEV_RAIDZ_64MUL_4(*pqr->r, mask);
*pqr->r ^= *src;
}
return (0);
}
static void
vdev_raidz_generate_parity_p(raidz_row_t *rr)
{
uint64_t *p = abd_to_buf(rr->rr_col[VDEV_RAIDZ_P].rc_abd);
for (int c = rr->rr_firstdatacol; c < rr->rr_cols; c++) {
abd_t *src = rr->rr_col[c].rc_abd;
if (c == rr->rr_firstdatacol) {
abd_copy_to_buf(p, src, rr->rr_col[c].rc_size);
} else {
struct pqr_struct pqr = { p, NULL, NULL };
(void) abd_iterate_func(src, 0, rr->rr_col[c].rc_size,
vdev_raidz_p_func, &pqr);
}
}
}
static void
vdev_raidz_generate_parity_pq(raidz_row_t *rr)
{
uint64_t *p = abd_to_buf(rr->rr_col[VDEV_RAIDZ_P].rc_abd);
uint64_t *q = abd_to_buf(rr->rr_col[VDEV_RAIDZ_Q].rc_abd);
uint64_t pcnt = rr->rr_col[VDEV_RAIDZ_P].rc_size / sizeof (p[0]);
ASSERT(rr->rr_col[VDEV_RAIDZ_P].rc_size ==
rr->rr_col[VDEV_RAIDZ_Q].rc_size);
for (int c = rr->rr_firstdatacol; c < rr->rr_cols; c++) {
abd_t *src = rr->rr_col[c].rc_abd;
uint64_t ccnt = rr->rr_col[c].rc_size / sizeof (p[0]);
if (c == rr->rr_firstdatacol) {
ASSERT(ccnt == pcnt || ccnt == 0);
abd_copy_to_buf(p, src, rr->rr_col[c].rc_size);
(void) memcpy(q, p, rr->rr_col[c].rc_size);
for (uint64_t i = ccnt; i < pcnt; i++) {
p[i] = 0;
q[i] = 0;
}
} else {
struct pqr_struct pqr = { p, q, NULL };
ASSERT(ccnt <= pcnt);
(void) abd_iterate_func(src, 0, rr->rr_col[c].rc_size,
vdev_raidz_pq_func, &pqr);
/*
* Treat short columns as though they are full of 0s.
* Note that there's therefore nothing needed for P.
*/
uint64_t mask;
for (uint64_t i = ccnt; i < pcnt; i++) {
VDEV_RAIDZ_64MUL_2(q[i], mask);
}
}
}
}
static void
vdev_raidz_generate_parity_pqr(raidz_row_t *rr)
{
uint64_t *p = abd_to_buf(rr->rr_col[VDEV_RAIDZ_P].rc_abd);
uint64_t *q = abd_to_buf(rr->rr_col[VDEV_RAIDZ_Q].rc_abd);
uint64_t *r = abd_to_buf(rr->rr_col[VDEV_RAIDZ_R].rc_abd);
uint64_t pcnt = rr->rr_col[VDEV_RAIDZ_P].rc_size / sizeof (p[0]);
ASSERT(rr->rr_col[VDEV_RAIDZ_P].rc_size ==
rr->rr_col[VDEV_RAIDZ_Q].rc_size);
ASSERT(rr->rr_col[VDEV_RAIDZ_P].rc_size ==
rr->rr_col[VDEV_RAIDZ_R].rc_size);
for (int c = rr->rr_firstdatacol; c < rr->rr_cols; c++) {
abd_t *src = rr->rr_col[c].rc_abd;
uint64_t ccnt = rr->rr_col[c].rc_size / sizeof (p[0]);
if (c == rr->rr_firstdatacol) {
ASSERT(ccnt == pcnt || ccnt == 0);
abd_copy_to_buf(p, src, rr->rr_col[c].rc_size);
(void) memcpy(q, p, rr->rr_col[c].rc_size);
(void) memcpy(r, p, rr->rr_col[c].rc_size);
for (uint64_t i = ccnt; i < pcnt; i++) {
p[i] = 0;
q[i] = 0;
r[i] = 0;
}
} else {
struct pqr_struct pqr = { p, q, r };
ASSERT(ccnt <= pcnt);
(void) abd_iterate_func(src, 0, rr->rr_col[c].rc_size,
vdev_raidz_pqr_func, &pqr);
/*
* Treat short columns as though they are full of 0s.
* Note that there's therefore nothing needed for P.
*/
uint64_t mask;
for (uint64_t i = ccnt; i < pcnt; i++) {
VDEV_RAIDZ_64MUL_2(q[i], mask);
VDEV_RAIDZ_64MUL_4(r[i], mask);
}
}
}
}
/*
* Generate RAID parity in the first virtual columns according to the number of
* parity columns available.
*/
void
vdev_raidz_generate_parity_row(raidz_map_t *rm, raidz_row_t *rr)
{
ASSERT3U(rr->rr_cols, !=, 0);
/* Generate using the new math implementation */
if (vdev_raidz_math_generate(rm, rr) != RAIDZ_ORIGINAL_IMPL)
return;
switch (rr->rr_firstdatacol) {
case 1:
vdev_raidz_generate_parity_p(rr);
break;
case 2:
vdev_raidz_generate_parity_pq(rr);
break;
case 3:
vdev_raidz_generate_parity_pqr(rr);
break;
default:
cmn_err(CE_PANIC, "invalid RAID-Z configuration");
}
}
void
vdev_raidz_generate_parity(raidz_map_t *rm)
{
for (int i = 0; i < rm->rm_nrows; i++) {
raidz_row_t *rr = rm->rm_row[i];
vdev_raidz_generate_parity_row(rm, rr);
}
}
/* 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++) {
int j;
uint8_t *b;
*dst ^= *rq->q;
for (j = 0, b = (uint8_t *)dst; j < 8; j++, b++) {
*b = vdev_raidz_exp2(*b, rq->exp);
}
}
return (0);
}
struct reconst_pq_struct {
uint8_t *p;
uint8_t *q;
uint8_t *pxy;
uint8_t *qxy;
int aexp;
int bexp;
};
static int
vdev_raidz_reconst_pq_func(void *xbuf, void *ybuf, size_t size, void *private)
{
struct reconst_pq_struct *rpq = private;
uint8_t *xd = xbuf;
uint8_t *yd = ybuf;
for (int i = 0; i < size;
i++, rpq->p++, rpq->q++, rpq->pxy++, rpq->qxy++, xd++, yd++) {
*xd = vdev_raidz_exp2(*rpq->p ^ *rpq->pxy, rpq->aexp) ^
vdev_raidz_exp2(*rpq->q ^ *rpq->qxy, rpq->bexp);
*yd = *rpq->p ^ *rpq->pxy ^ *xd;
}
return (0);
}
static int
vdev_raidz_reconst_pq_tail_func(void *xbuf, size_t size, void *private)
{
struct reconst_pq_struct *rpq = private;
uint8_t *xd = xbuf;
for (int i = 0; i < size;
i++, rpq->p++, rpq->q++, rpq->pxy++, rpq->qxy++, xd++) {
/* same operation as vdev_raidz_reconst_pq_func() on xd */
*xd = vdev_raidz_exp2(*rpq->p ^ *rpq->pxy, rpq->aexp) ^
vdev_raidz_exp2(*rpq->q ^ *rpq->qxy, rpq->bexp);
}
return (0);
}
static void
vdev_raidz_reconstruct_p(raidz_row_t *rr, int *tgts, int ntgts)
{
int x = tgts[0];
abd_t *dst, *src;
ASSERT3U(ntgts, ==, 1);
ASSERT3U(x, >=, rr->rr_firstdatacol);
ASSERT3U(x, <, rr->rr_cols);
ASSERT3U(rr->rr_col[x].rc_size, <=, rr->rr_col[VDEV_RAIDZ_P].rc_size);
src = rr->rr_col[VDEV_RAIDZ_P].rc_abd;
dst = rr->rr_col[x].rc_abd;
abd_copy_from_buf(dst, abd_to_buf(src), rr->rr_col[x].rc_size);
for (int c = rr->rr_firstdatacol; c < rr->rr_cols; c++) {
uint64_t size = MIN(rr->rr_col[x].rc_size,
rr->rr_col[c].rc_size);
src = rr->rr_col[c].rc_abd;
if (c == x)
continue;
(void) abd_iterate_func2(dst, src, 0, 0, size,
vdev_raidz_reconst_p_func, NULL);
}
}
static void
vdev_raidz_reconstruct_q(raidz_row_t *rr, int *tgts, int ntgts)
{
int x = tgts[0];
int c, exp;
abd_t *dst, *src;
ASSERT(ntgts == 1);
ASSERT(rr->rr_col[x].rc_size <= rr->rr_col[VDEV_RAIDZ_Q].rc_size);
for (c = rr->rr_firstdatacol; c < rr->rr_cols; c++) {
uint64_t size = (c == x) ? 0 : MIN(rr->rr_col[x].rc_size,
rr->rr_col[c].rc_size);
src = rr->rr_col[c].rc_abd;
dst = rr->rr_col[x].rc_abd;
if (c == rr->rr_firstdatacol) {
abd_copy(dst, src, size);
if (rr->rr_col[x].rc_size > size) {
abd_zero_off(dst, size,
rr->rr_col[x].rc_size - size);
}
} else {
ASSERT3U(size, <=, rr->rr_col[x].rc_size);
(void) abd_iterate_func2(dst, src, 0, 0, size,
vdev_raidz_reconst_q_pre_func, NULL);
(void) abd_iterate_func(dst,
size, rr->rr_col[x].rc_size - size,
vdev_raidz_reconst_q_pre_tail_func, NULL);
}
}
src = rr->rr_col[VDEV_RAIDZ_Q].rc_abd;
dst = rr->rr_col[x].rc_abd;
exp = 255 - (rr->rr_cols - 1 - x);
struct reconst_q_struct rq = { abd_to_buf(src), exp };
(void) abd_iterate_func(dst, 0, rr->rr_col[x].rc_size,
vdev_raidz_reconst_q_post_func, &rq);
}
static void
vdev_raidz_reconstruct_pq(raidz_row_t *rr, int *tgts, int ntgts)
{
uint8_t *p, *q, *pxy, *qxy, tmp, a, b, aexp, bexp;
abd_t *pdata, *qdata;
uint64_t xsize, ysize;
int x = tgts[0];
int y = tgts[1];
abd_t *xd, *yd;
ASSERT(ntgts == 2);
ASSERT(x < y);
ASSERT(x >= rr->rr_firstdatacol);
ASSERT(y < rr->rr_cols);
ASSERT(rr->rr_col[x].rc_size >= rr->rr_col[y].rc_size);
/*
* Move the parity data aside -- we're going to compute parity as
* though columns x and y were full of zeros -- Pxy and Qxy. We want to
* reuse the parity generation mechanism without trashing the actual
* parity so we make those columns appear to be full of zeros by
* setting their lengths to zero.
*/
pdata = rr->rr_col[VDEV_RAIDZ_P].rc_abd;
qdata = rr->rr_col[VDEV_RAIDZ_Q].rc_abd;
xsize = rr->rr_col[x].rc_size;
ysize = rr->rr_col[y].rc_size;
rr->rr_col[VDEV_RAIDZ_P].rc_abd =
abd_alloc_linear(rr->rr_col[VDEV_RAIDZ_P].rc_size, B_TRUE);
rr->rr_col[VDEV_RAIDZ_Q].rc_abd =
abd_alloc_linear(rr->rr_col[VDEV_RAIDZ_Q].rc_size, B_TRUE);
rr->rr_col[x].rc_size = 0;
rr->rr_col[y].rc_size = 0;
vdev_raidz_generate_parity_pq(rr);
rr->rr_col[x].rc_size = xsize;
rr->rr_col[y].rc_size = ysize;
p = abd_to_buf(pdata);
q = abd_to_buf(qdata);
pxy = abd_to_buf(rr->rr_col[VDEV_RAIDZ_P].rc_abd);
qxy = abd_to_buf(rr->rr_col[VDEV_RAIDZ_Q].rc_abd);
xd = rr->rr_col[x].rc_abd;
yd = rr->rr_col[y].rc_abd;
/*
* We now have:
* Pxy = P + D_x + D_y
* Qxy = Q + 2^(ndevs - 1 - x) * D_x + 2^(ndevs - 1 - y) * D_y
*
* We can then solve for D_x:
* D_x = A * (P + Pxy) + B * (Q + Qxy)
* where
* A = 2^(x - y) * (2^(x - y) + 1)^-1
* B = 2^(ndevs - 1 - x) * (2^(x - y) + 1)^-1
*
* With D_x in hand, we can easily solve for D_y:
* D_y = P + Pxy + D_x
*/
a = vdev_raidz_pow2[255 + x - y];
b = vdev_raidz_pow2[255 - (rr->rr_cols - 1 - x)];
tmp = 255 - vdev_raidz_log2[a ^ 1];
aexp = vdev_raidz_log2[vdev_raidz_exp2(a, tmp)];
bexp = vdev_raidz_log2[vdev_raidz_exp2(b, tmp)];
ASSERT3U(xsize, >=, ysize);
struct reconst_pq_struct rpq = { p, q, pxy, qxy, aexp, bexp };
(void) abd_iterate_func2(xd, yd, 0, 0, ysize,
vdev_raidz_reconst_pq_func, &rpq);
(void) abd_iterate_func(xd, ysize, xsize - ysize,
vdev_raidz_reconst_pq_tail_func, &rpq);
abd_free(rr->rr_col[VDEV_RAIDZ_P].rc_abd);
abd_free(rr->rr_col[VDEV_RAIDZ_Q].rc_abd);
/*
* Restore the saved parity data.
*/
rr->rr_col[VDEV_RAIDZ_P].rc_abd = pdata;
rr->rr_col[VDEV_RAIDZ_Q].rc_abd = qdata;
}
/* BEGIN CSTYLED */
/*
* In the general case of reconstruction, we must solve the system of linear
* equations defined by the coefficients used to generate parity as well as
* the contents of the data and parity disks. This can be expressed with
* vectors for the original data (D) and the actual data (d) and parity (p)
* and a matrix composed of the identity matrix (I) and a dispersal matrix (V):
*
* __ __ __ __
* | | __ __ | p_0 |
* | V | | D_0 | | p_m-1 |
* | | x | : | = | d_0 |
* | I | | D_n-1 | | : |
* | | ~~ ~~ | d_n-1 |
* ~~ ~~ ~~ ~~
*
* I is simply a square identity matrix of size n, and V is a vandermonde
* matrix defined by the coefficients we chose for the various parity columns
* (1, 2, 4). Note that these values were chosen both for simplicity, speedy
* computation as well as linear separability.
*
* __ __ __ __
* | 1 .. 1 1 1 | | p_0 |
* | 2^n-1 .. 4 2 1 | __ __ | : |
* | 4^n-1 .. 16 4 1 | | D_0 | | p_m-1 |
* | 1 .. 0 0 0 | | D_1 | | d_0 |
* | 0 .. 0 0 0 | x | D_2 | = | d_1 |
* | : : : : | | : | | d_2 |
* | 0 .. 1 0 0 | | D_n-1 | | : |
* | 0 .. 0 1 0 | ~~ ~~ | : |
* | 0 .. 0 0 1 | | d_n-1 |
* ~~ ~~ ~~ ~~
*
* Note that I, V, d, and p are known. To compute D, we must invert the
* matrix and use the known data and parity values to reconstruct the unknown
* data values. We begin by removing the rows in V|I and d|p that correspond
* to failed or missing columns; we then make V|I square (n x n) and d|p
* sized n by removing rows corresponding to unused parity from the bottom up
* to generate (V|I)' and (d|p)'. We can then generate the inverse of (V|I)'
* using Gauss-Jordan elimination. In the example below we use m=3 parity
* columns, n=8 data columns, with errors in d_1, d_2, and p_1:
* __ __
* | 1 1 1 1 1 1 1 1 |
* | 128 64 32 16 8 4 2 1 | <-----+-+-- missing disks
* | 19 205 116 29 64 16 4 1 | / /
* | 1 0 0 0 0 0 0 0 | / /
* | 0 1 0 0 0 0 0 0 | <--' /
* (V|I) = | 0 0 1 0 0 0 0 0 | <---'
* | 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 |
* ~~ ~~
* __ __
* | 1 1 1 1 1 1 1 1 |
* | 128 64 32 16 8 4 2 1 |
* | 19 205 116 29 64 16 4 1 |
* | 1 0 0 0 0 0 0 0 |
* | 0 1 0 0 0 0 0 0 |
* (V|I)' = | 0 0 1 0 0 0 0 0 |
* | 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 |
* ~~ ~~
*
* Here we employ Gauss-Jordan elimination to find the inverse of (V|I)'. We
* have carefully chosen the seed values 1, 2, and 4 to ensure that this
* matrix is not singular.
* __ __
* | 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 |
* | 19 205 116 29 64 16 4 1 0 1 0 0 0 0 0 0 |
* | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 |
* | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 |
* ~~ ~~
* __ __
* | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 |
* | 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 |
* | 19 205 116 29 64 16 4 1 0 1 0 0 0 0 0 0 |
* | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 |
* ~~ ~~
* __ __
* | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 |
* | 0 1 1 0 0 0 0 0 1 0 1 1 1 1 1 1 |
* | 0 205 116 0 0 0 0 0 0 1 19 29 64 16 4 1 |
* | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 |
* ~~ ~~
* __ __
* | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 |
* | 0 1 1 0 0 0 0 0 1 0 1 1 1 1 1 1 |
* | 0 0 185 0 0 0 0 0 205 1 222 208 141 221 201 204 |
* | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 |
* ~~ ~~
* __ __
* | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 |
* | 0 1 1 0 0 0 0 0 1 0 1 1 1 1 1 1 |
* | 0 0 1 0 0 0 0 0 166 100 4 40 158 168 216 209 |
* | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 |
* ~~ ~~
* __ __
* | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 |
* | 0 1 0 0 0 0 0 0 167 100 5 41 159 169 217 208 |
* | 0 0 1 0 0 0 0 0 166 100 4 40 158 168 216 209 |
* | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 |
* ~~ ~~
* __ __
* | 0 0 1 0 0 0 0 0 |
* | 167 100 5 41 159 169 217 208 |
* | 166 100 4 40 158 168 216 209 |
* (V|I)'^-1 = | 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 |
* ~~ ~~
*
* We can then simply compute D = (V|I)'^-1 x (d|p)' to discover the values
* of the missing data.
*
* As is apparent from the example above, the only non-trivial rows in the
* inverse matrix correspond to the data disks that we're trying to
* reconstruct. Indeed, those are the only rows we need as the others would
* only be useful for reconstructing data known or assumed to be valid. For
* that reason, we only build the coefficients in the rows that correspond to
* targeted columns.
*/
/* END CSTYLED */
static void
vdev_raidz_matrix_init(raidz_row_t *rr, int n, int nmap, int *map,
uint8_t **rows)
{
int i, j;
int pow;
ASSERT(n == rr->rr_cols - rr->rr_firstdatacol);
/*
* Fill in the missing rows of interest.
*/
for (i = 0; i < nmap; i++) {
ASSERT3S(0, <=, map[i]);
ASSERT3S(map[i], <=, 2);
pow = map[i] * n;
if (pow > 255)
pow -= 255;
ASSERT(pow <= 255);
for (j = 0; j < n; j++) {
pow -= map[i];
if (pow < 0)
pow += 255;
rows[i][j] = vdev_raidz_pow2[pow];
}
}
}
static void
vdev_raidz_matrix_invert(raidz_row_t *rr, int n, int nmissing, int *missing,
uint8_t **rows, uint8_t **invrows, const uint8_t *used)
{
int i, j, ii, jj;
uint8_t log;
/*
* Assert that the first nmissing entries from the array of used
* columns correspond to parity columns and that subsequent entries
* correspond to data columns.
*/
for (i = 0; i < nmissing; i++) {
ASSERT3S(used[i], <, rr->rr_firstdatacol);
}
for (; i < n; i++) {
ASSERT3S(used[i], >=, rr->rr_firstdatacol);
}
/*
* First initialize the storage where we'll compute the inverse rows.
*/
for (i = 0; i < nmissing; i++) {
for (j = 0; j < n; j++) {
invrows[i][j] = (i == j) ? 1 : 0;
}
}
/*
* Subtract all trivial rows from the rows of consequence.
*/
for (i = 0; i < nmissing; i++) {
for (j = nmissing; j < n; j++) {
ASSERT3U(used[j], >=, rr->rr_firstdatacol);
jj = used[j] - rr->rr_firstdatacol;
ASSERT3S(jj, <, n);
invrows[i][j] = rows[i][jj];
rows[i][jj] = 0;
}
}
/*
* For each of the rows of interest, we must normalize it and subtract
* a multiple of it from the other rows.
*/
for (i = 0; i < nmissing; i++) {
for (j = 0; j < missing[i]; j++) {
ASSERT0(rows[i][j]);
}
ASSERT3U(rows[i][missing[i]], !=, 0);
/*
* Compute the inverse of the first element and multiply each
* element in the row by that value.
*/
log = 255 - vdev_raidz_log2[rows[i][missing[i]]];
for (j = 0; j < n; j++) {
rows[i][j] = vdev_raidz_exp2(rows[i][j], log);
invrows[i][j] = vdev_raidz_exp2(invrows[i][j], log);
}
for (ii = 0; ii < nmissing; ii++) {
if (i == ii)
continue;
ASSERT3U(rows[ii][missing[i]], !=, 0);
log = vdev_raidz_log2[rows[ii][missing[i]]];
for (j = 0; j < n; j++) {
rows[ii][j] ^=
vdev_raidz_exp2(rows[i][j], log);
invrows[ii][j] ^=
vdev_raidz_exp2(invrows[i][j], log);
}
}
}
/*
* Verify that the data that is left in the rows are properly part of
* an identity matrix.
*/
for (i = 0; i < nmissing; i++) {
for (j = 0; j < n; j++) {
if (j == missing[i]) {
ASSERT3U(rows[i][j], ==, 1);
} else {
ASSERT0(rows[i][j]);
}
}
}
}
static void
vdev_raidz_matrix_reconstruct(raidz_row_t *rr, int n, int nmissing,
int *missing, uint8_t **invrows, const uint8_t *used)
{
int i, j, x, cc, c;
uint8_t *src;
uint64_t ccount;
uint8_t *dst[VDEV_RAIDZ_MAXPARITY] = { NULL };
uint64_t dcount[VDEV_RAIDZ_MAXPARITY] = { 0 };
uint8_t log = 0;
uint8_t val;
int ll;
uint8_t *invlog[VDEV_RAIDZ_MAXPARITY];
uint8_t *p, *pp;
size_t psize;
psize = sizeof (invlog[0][0]) * n * nmissing;
p = kmem_alloc(psize, KM_SLEEP);
for (pp = p, i = 0; i < nmissing; i++) {
invlog[i] = pp;
pp += n;
}
for (i = 0; i < nmissing; i++) {
for (j = 0; j < n; j++) {
ASSERT3U(invrows[i][j], !=, 0);
invlog[i][j] = vdev_raidz_log2[invrows[i][j]];
}
}
for (i = 0; i < n; i++) {
c = used[i];
ASSERT3U(c, <, rr->rr_cols);
ccount = rr->rr_col[c].rc_size;
ASSERT(ccount >= rr->rr_col[missing[0]].rc_size || i > 0);
if (ccount == 0)
continue;
src = abd_to_buf(rr->rr_col[c].rc_abd);
for (j = 0; j < nmissing; j++) {
cc = missing[j] + rr->rr_firstdatacol;
ASSERT3U(cc, >=, rr->rr_firstdatacol);
ASSERT3U(cc, <, rr->rr_cols);
ASSERT3U(cc, !=, c);
dcount[j] = rr->rr_col[cc].rc_size;
if (dcount[j] != 0)
dst[j] = abd_to_buf(rr->rr_col[cc].rc_abd);
}
for (x = 0; x < ccount; x++, src++) {
if (*src != 0)
log = vdev_raidz_log2[*src];
for (cc = 0; cc < nmissing; cc++) {
if (x >= dcount[cc])
continue;
if (*src == 0) {
val = 0;
} else {
if ((ll = log + invlog[cc][i]) >= 255)
ll -= 255;
val = vdev_raidz_pow2[ll];
}
if (i == 0)
dst[cc][x] = val;
else
dst[cc][x] ^= val;
}
}
}
kmem_free(p, psize);
}
static void
vdev_raidz_reconstruct_general(raidz_row_t *rr, int *tgts, int ntgts)
{
int n, i, c, t, tt;
int nmissing_rows;
int missing_rows[VDEV_RAIDZ_MAXPARITY];
int parity_map[VDEV_RAIDZ_MAXPARITY];
uint8_t *p, *pp;
size_t psize;
uint8_t *rows[VDEV_RAIDZ_MAXPARITY];
uint8_t *invrows[VDEV_RAIDZ_MAXPARITY];
uint8_t *used;
abd_t **bufs = NULL;
/*
* Matrix reconstruction can't use scatter ABDs yet, so we allocate
* temporary linear ABDs if any non-linear ABDs are found.
*/
for (i = rr->rr_firstdatacol; i < rr->rr_cols; i++) {
if (!abd_is_linear(rr->rr_col[i].rc_abd)) {
bufs = kmem_alloc(rr->rr_cols * sizeof (abd_t *),
KM_PUSHPAGE);
for (c = rr->rr_firstdatacol; c < rr->rr_cols; c++) {
raidz_col_t *col = &rr->rr_col[c];
bufs[c] = col->rc_abd;
if (bufs[c] != NULL) {
col->rc_abd = abd_alloc_linear(
col->rc_size, B_TRUE);
abd_copy(col->rc_abd, bufs[c],
col->rc_size);
}
}
break;
}
}
n = rr->rr_cols - rr->rr_firstdatacol;
/*
* Figure out which data columns are missing.
*/
nmissing_rows = 0;
for (t = 0; t < ntgts; t++) {
if (tgts[t] >= rr->rr_firstdatacol) {
missing_rows[nmissing_rows++] =
tgts[t] - rr->rr_firstdatacol;
}
}
/*
* Figure out which parity columns to use to help generate the missing
* data columns.
*/
for (tt = 0, c = 0, i = 0; i < nmissing_rows; c++) {
ASSERT(tt < ntgts);
ASSERT(c < rr->rr_firstdatacol);
/*
* Skip any targeted parity columns.
*/
if (c == tgts[tt]) {
tt++;
continue;
}
parity_map[i] = c;
i++;
}
psize = (sizeof (rows[0][0]) + sizeof (invrows[0][0])) *
nmissing_rows * n + sizeof (used[0]) * n;
p = kmem_alloc(psize, KM_SLEEP);
for (pp = p, i = 0; i < nmissing_rows; i++) {
rows[i] = pp;
pp += n;
invrows[i] = pp;
pp += n;
}
used = pp;
for (i = 0; i < nmissing_rows; i++) {
used[i] = parity_map[i];
}
for (tt = 0, c = rr->rr_firstdatacol; c < rr->rr_cols; c++) {
if (tt < nmissing_rows &&
c == missing_rows[tt] + rr->rr_firstdatacol) {
tt++;
continue;
}
ASSERT3S(i, <, n);
used[i] = c;
i++;
}
/*
* Initialize the interesting rows of the matrix.
*/
vdev_raidz_matrix_init(rr, n, nmissing_rows, parity_map, rows);
/*
* Invert the matrix.
*/
vdev_raidz_matrix_invert(rr, n, nmissing_rows, missing_rows, rows,
invrows, used);
/*
* Reconstruct the missing data using the generated matrix.
*/
vdev_raidz_matrix_reconstruct(rr, n, nmissing_rows, missing_rows,
invrows, used);
kmem_free(p, psize);
/*
* copy back from temporary linear abds and free them
*/
if (bufs) {
for (c = rr->rr_firstdatacol; c < rr->rr_cols; c++) {
raidz_col_t *col = &rr->rr_col[c];
if (bufs[c] != NULL) {
abd_copy(bufs[c], col->rc_abd, col->rc_size);
abd_free(col->rc_abd);
}
col->rc_abd = bufs[c];
}
kmem_free(bufs, rr->rr_cols * sizeof (abd_t *));
}
}
static void
vdev_raidz_reconstruct_row(raidz_map_t *rm, raidz_row_t *rr,
const int *t, int nt)
{
int tgts[VDEV_RAIDZ_MAXPARITY], *dt;
int ntgts;
int i, c, ret;
int nbadparity, nbaddata;
int parity_valid[VDEV_RAIDZ_MAXPARITY];
nbadparity = rr->rr_firstdatacol;
nbaddata = rr->rr_cols - nbadparity;
ntgts = 0;
for (i = 0, c = 0; c < rr->rr_cols; c++) {
if (c < rr->rr_firstdatacol)
parity_valid[c] = B_FALSE;
if (i < nt && c == t[i]) {
tgts[ntgts++] = c;
i++;
} else if (rr->rr_col[c].rc_error != 0) {
tgts[ntgts++] = c;
} else if (c >= rr->rr_firstdatacol) {
nbaddata--;
} else {
parity_valid[c] = B_TRUE;
nbadparity--;
}
}
ASSERT(ntgts >= nt);
ASSERT(nbaddata >= 0);
ASSERT(nbaddata + nbadparity == ntgts);
dt = &tgts[nbadparity];
/* Reconstruct using the new math implementation */
ret = vdev_raidz_math_reconstruct(rm, rr, parity_valid, dt, nbaddata);
if (ret != RAIDZ_ORIGINAL_IMPL)
return;
/*
* See if we can use any of our optimized reconstruction routines.
*/
switch (nbaddata) {
case 1:
if (parity_valid[VDEV_RAIDZ_P]) {
vdev_raidz_reconstruct_p(rr, dt, 1);
return;
}
ASSERT(rr->rr_firstdatacol > 1);
if (parity_valid[VDEV_RAIDZ_Q]) {
vdev_raidz_reconstruct_q(rr, dt, 1);
return;
}
ASSERT(rr->rr_firstdatacol > 2);
break;
case 2:
ASSERT(rr->rr_firstdatacol > 1);
if (parity_valid[VDEV_RAIDZ_P] &&
parity_valid[VDEV_RAIDZ_Q]) {
vdev_raidz_reconstruct_pq(rr, dt, 2);
return;
}
ASSERT(rr->rr_firstdatacol > 2);
break;
}
vdev_raidz_reconstruct_general(rr, tgts, ntgts);
}
static int
vdev_raidz_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
uint64_t *logical_ashift, uint64_t *physical_ashift)
{
vdev_raidz_t *vdrz = vd->vdev_tsd;
uint64_t nparity = vdrz->vd_nparity;
int c;
int lasterror = 0;
int numerrors = 0;
ASSERT(nparity > 0);
if (nparity > VDEV_RAIDZ_MAXPARITY ||
vd->vdev_children < nparity + 1) {
vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
return (SET_ERROR(EINVAL));
}
vdev_open_children(vd);
for (c = 0; c < vd->vdev_children; c++) {
vdev_t *cvd = vd->vdev_child[c];
if (cvd->vdev_open_error != 0) {
lasterror = cvd->vdev_open_error;
numerrors++;
continue;
}
*asize = MIN(*asize - 1, cvd->vdev_asize - 1) + 1;
*max_asize = MIN(*max_asize - 1, cvd->vdev_max_asize - 1) + 1;
*logical_ashift = MAX(*logical_ashift, cvd->vdev_ashift);
*physical_ashift = MAX(*physical_ashift,
cvd->vdev_physical_ashift);
}
*asize *= vd->vdev_children;
*max_asize *= vd->vdev_children;
if (numerrors > nparity) {
vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
return (lasterror);
}
return (0);
}
static void
vdev_raidz_close(vdev_t *vd)
{
for (int c = 0; c < vd->vdev_children; c++) {
if (vd->vdev_child[c] != NULL)
vdev_close(vd->vdev_child[c]);
}
}
static uint64_t
vdev_raidz_asize(vdev_t *vd, uint64_t psize)
{
vdev_raidz_t *vdrz = vd->vdev_tsd;
uint64_t asize;
uint64_t ashift = vd->vdev_top->vdev_ashift;
uint64_t cols = vdrz->vd_logical_width;
uint64_t nparity = vdrz->vd_nparity;
asize = ((psize - 1) >> ashift) + 1;
asize += nparity * ((asize + cols - nparity - 1) / (cols - nparity));
asize = roundup(asize, nparity + 1) << ashift;
return (asize);
}
/*
* The allocatable space for a raidz vdev is N * sizeof(smallest child)
* so each child must provide at least 1/Nth of its asize.
*/
static uint64_t
vdev_raidz_min_asize(vdev_t *vd)
{
return ((vd->vdev_min_asize + vd->vdev_children - 1) /
vd->vdev_children);
}
void
vdev_raidz_child_done(zio_t *zio)
{
raidz_col_t *rc = zio->io_private;
ASSERT3P(rc->rc_abd, !=, NULL);
rc->rc_error = zio->io_error;
rc->rc_tried = 1;
rc->rc_skipped = 0;
}
static void
vdev_raidz_io_verify(vdev_t *vd, raidz_row_t *rr, int col)
{
#ifdef ZFS_DEBUG
vdev_t *tvd = vd->vdev_top;
range_seg64_t logical_rs, physical_rs, remain_rs;
logical_rs.rs_start = rr->rr_offset;
logical_rs.rs_end = logical_rs.rs_start +
vdev_raidz_asize(vd, rr->rr_size);
raidz_col_t *rc = &rr->rr_col[col];
vdev_t *cvd = vd->vdev_child[rc->rc_devidx];
vdev_xlate(cvd, &logical_rs, &physical_rs, &remain_rs);
ASSERT(vdev_xlate_is_empty(&remain_rs));
ASSERT3U(rc->rc_offset, ==, physical_rs.rs_start);
ASSERT3U(rc->rc_offset, <, physical_rs.rs_end);
/*
* It would be nice to assert that rs_end is equal
* to rc_offset + rc_size but there might be an
* optional I/O at the end that is not accounted in
* rc_size.
*/
if (physical_rs.rs_end > rc->rc_offset + rc->rc_size) {
ASSERT3U(physical_rs.rs_end, ==, rc->rc_offset +
rc->rc_size + (1 << tvd->vdev_ashift));
} else {
ASSERT3U(physical_rs.rs_end, ==, rc->rc_offset + rc->rc_size);
}
#endif
}
static void
vdev_raidz_io_start_write(zio_t *zio, raidz_row_t *rr, uint64_t ashift)
{
vdev_t *vd = zio->io_vd;
raidz_map_t *rm = zio->io_vsd;
vdev_raidz_generate_parity_row(rm, rr);
for (int c = 0; c < rr->rr_scols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
vdev_t *cvd = vd->vdev_child[rc->rc_devidx];
/* Verify physical to logical translation */
vdev_raidz_io_verify(vd, rr, c);
if (rc->rc_size > 0) {
ASSERT3P(rc->rc_abd, !=, NULL);
zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
rc->rc_offset, rc->rc_abd,
abd_get_size(rc->rc_abd), zio->io_type,
zio->io_priority, 0, vdev_raidz_child_done, rc));
} else {
/*
* Generate optional write for skip sector to improve
* aggregation contiguity.
*/
ASSERT3P(rc->rc_abd, ==, NULL);
zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
rc->rc_offset, NULL, 1ULL << ashift,
zio->io_type, zio->io_priority,
ZIO_FLAG_NODATA | ZIO_FLAG_OPTIONAL, NULL,
NULL));
}
}
}
static void
vdev_raidz_io_start_read(zio_t *zio, raidz_row_t *rr)
{
vdev_t *vd = zio->io_vd;
/*
* Iterate over the columns in reverse order so that we hit the parity
* last -- any errors along the way will force us to read the parity.
*/
for (int c = rr->rr_cols - 1; c >= 0; c--) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_size == 0)
continue;
vdev_t *cvd = vd->vdev_child[rc->rc_devidx];
if (!vdev_readable(cvd)) {
if (c >= rr->rr_firstdatacol)
rr->rr_missingdata++;
else
rr->rr_missingparity++;
rc->rc_error = SET_ERROR(ENXIO);
rc->rc_tried = 1; /* don't even try */
rc->rc_skipped = 1;
continue;
}
if (vdev_dtl_contains(cvd, DTL_MISSING, zio->io_txg, 1)) {
if (c >= rr->rr_firstdatacol)
rr->rr_missingdata++;
else
rr->rr_missingparity++;
rc->rc_error = SET_ERROR(ESTALE);
rc->rc_skipped = 1;
continue;
}
if (c >= rr->rr_firstdatacol || rr->rr_missingdata > 0 ||
(zio->io_flags & (ZIO_FLAG_SCRUB | ZIO_FLAG_RESILVER))) {
zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
rc->rc_offset, rc->rc_abd, rc->rc_size,
zio->io_type, zio->io_priority, 0,
vdev_raidz_child_done, rc));
}
}
}
/*
* Start an IO operation on a RAIDZ VDev
*
* Outline:
* - For write operations:
* 1. Generate the parity data
* 2. Create child zio write operations to each column's vdev, for both
* data and parity.
* 3. If the column skips any sectors for padding, create optional dummy
* write zio children for those areas to improve aggregation continuity.
* - For read operations:
* 1. Create child zio read operations to each data column's vdev to read
* the range of data required for zio.
* 2. If this is a scrub or resilver operation, or if any of the data
* vdevs have had errors, then create zio read operations to the parity
* columns' VDevs as well.
*/
static void
vdev_raidz_io_start(zio_t *zio)
{
vdev_t *vd = zio->io_vd;
vdev_t *tvd = vd->vdev_top;
vdev_raidz_t *vdrz = vd->vdev_tsd;
raidz_map_t *rm = vdev_raidz_map_alloc(zio, tvd->vdev_ashift,
vdrz->vd_logical_width, vdrz->vd_nparity);
zio->io_vsd = rm;
zio->io_vsd_ops = &vdev_raidz_vsd_ops;
/*
* Until raidz expansion is implemented all maps for a raidz vdev
* contain a single row.
*/
ASSERT3U(rm->rm_nrows, ==, 1);
raidz_row_t *rr = rm->rm_row[0];
if (zio->io_type == ZIO_TYPE_WRITE) {
vdev_raidz_io_start_write(zio, rr, tvd->vdev_ashift);
} else {
ASSERT(zio->io_type == ZIO_TYPE_READ);
vdev_raidz_io_start_read(zio, rr);
}
zio_execute(zio);
}
/*
* Report a checksum error for a child of a RAID-Z device.
*/
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->io_priority != ZIO_PRIORITY_REBUILD) {
zio_bad_cksum_t zbc;
raidz_map_t *rm = zio->io_vsd;
zbc.zbc_has_cksum = 0;
zbc.zbc_injected = rm->rm_ecksuminjected;
(void) zfs_ereport_post_checksum(zio->io_spa, vd,
&zio->io_bookmark, zio, rc->rc_offset, rc->rc_size,
rc->rc_abd, bad_data, &zbc);
mutex_enter(&vd->vdev_stat_lock);
vd->vdev_stat.vs_checksum_errors++;
mutex_exit(&vd->vdev_stat_lock);
}
}
/*
* We keep track of whether or not there were any injected errors, so that
* any ereports we generate can note it.
*/
static int
raidz_checksum_verify(zio_t *zio)
{
zio_bad_cksum_t zbc;
raidz_map_t *rm = zio->io_vsd;
bzero(&zbc, sizeof (zio_bad_cksum_t));
int ret = zio_checksum_error(zio, &zbc);
if (ret != 0 && zbc.zbc_injected != 0)
rm->rm_ecksuminjected = 1;
return (ret);
}
/*
* Generate the parity from the data columns. If we tried and were able to
* read the parity without error, verify that the generated parity matches the
* data we read. If it doesn't, we fire off a checksum error. Return the
* number of such failures.
*/
static int
raidz_parity_verify(zio_t *zio, raidz_row_t *rr)
{
abd_t *orig[VDEV_RAIDZ_MAXPARITY];
int c, ret = 0;
raidz_map_t *rm = zio->io_vsd;
raidz_col_t *rc;
blkptr_t *bp = zio->io_bp;
enum zio_checksum checksum = (bp == NULL ? zio->io_prop.zp_checksum :
(BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER : BP_GET_CHECKSUM(bp)));
if (checksum == ZIO_CHECKSUM_NOPARITY)
return (ret);
for (c = 0; c < rr->rr_firstdatacol; c++) {
rc = &rr->rr_col[c];
if (!rc->rc_tried || rc->rc_error != 0)
continue;
orig[c] = abd_alloc_sametype(rc->rc_abd, rc->rc_size);
abd_copy(orig[c], rc->rc_abd, rc->rc_size);
}
/*
* Regenerates parity even for !tried||rc_error!=0 columns. This
* isn't harmful but it does have the side effect of fixing stuff
* we didn't realize was necessary (i.e. even if we return 0).
*/
vdev_raidz_generate_parity_row(rm, rr);
for (c = 0; c < rr->rr_firstdatacol; c++) {
rc = &rr->rr_col[c];
if (!rc->rc_tried || rc->rc_error != 0)
continue;
if (abd_cmp(orig[c], rc->rc_abd) != 0) {
raidz_checksum_error(zio, rc, orig[c]);
rc->rc_error = SET_ERROR(ECKSUM);
ret++;
}
abd_free(orig[c]);
}
return (ret);
}
static int
vdev_raidz_worst_error(raidz_row_t *rr)
{
int error = 0;
for (int c = 0; c < rr->rr_cols; c++)
error = zio_worst_error(error, rr->rr_col[c].rc_error);
return (error);
}
static void
vdev_raidz_io_done_verified(zio_t *zio, raidz_row_t *rr)
{
int unexpected_errors = 0;
int parity_errors = 0;
int parity_untried = 0;
int data_errors = 0;
ASSERT3U(zio->io_type, ==, ZIO_TYPE_READ);
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_error) {
if (c < rr->rr_firstdatacol)
parity_errors++;
else
data_errors++;
if (!rc->rc_skipped)
unexpected_errors++;
} else if (c < rr->rr_firstdatacol && !rc->rc_tried) {
parity_untried++;
}
}
/*
* If we read more parity disks than were used for
* reconstruction, confirm that the other parity disks produced
* correct data.
*
* Note that we also regenerate parity when resilvering so we
* can write it out to failed devices later.
*/
if (parity_errors + parity_untried <
rr->rr_firstdatacol - data_errors ||
(zio->io_flags & ZIO_FLAG_RESILVER)) {
int n = raidz_parity_verify(zio, rr);
unexpected_errors += n;
ASSERT3U(parity_errors + n, <=, rr->rr_firstdatacol);
}
if (zio->io_error == 0 && spa_writeable(zio->io_spa) &&
(unexpected_errors > 0 || (zio->io_flags & ZIO_FLAG_RESILVER))) {
/*
* Use the good data we have in hand to repair damaged children.
*/
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
vdev_t *vd = zio->io_vd;
vdev_t *cvd = vd->vdev_child[rc->rc_devidx];
if (!rc->rc_allow_repair) {
continue;
} else if (!rc->rc_force_repair &&
(rc->rc_error == 0 || rc->rc_size == 0)) {
continue;
}
zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
rc->rc_offset, rc->rc_abd, rc->rc_size,
ZIO_TYPE_WRITE,
zio->io_priority == ZIO_PRIORITY_REBUILD ?
ZIO_PRIORITY_REBUILD : ZIO_PRIORITY_ASYNC_WRITE,
ZIO_FLAG_IO_REPAIR | (unexpected_errors ?
ZIO_FLAG_SELF_HEAL : 0), NULL, NULL));
}
}
}
static void
raidz_restore_orig_data(raidz_map_t *rm)
{
for (int i = 0; i < rm->rm_nrows; i++) {
raidz_row_t *rr = rm->rm_row[i];
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_need_orig_restore) {
abd_copy(rc->rc_abd,
rc->rc_orig_data, rc->rc_size);
rc->rc_need_orig_restore = B_FALSE;
}
}
}
}
/*
* returns EINVAL if reconstruction of the block will not be possible
* returns ECKSUM if this specific reconstruction failed
* returns 0 on successful reconstruction
*/
static int
raidz_reconstruct(zio_t *zio, int *ltgts, int ntgts, int nparity)
{
raidz_map_t *rm = zio->io_vsd;
/* Reconstruct each row */
for (int r = 0; r < rm->rm_nrows; r++) {
raidz_row_t *rr = rm->rm_row[r];
int my_tgts[VDEV_RAIDZ_MAXPARITY]; /* value is child id */
int t = 0;
int dead = 0;
int dead_data = 0;
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
ASSERT0(rc->rc_need_orig_restore);
if (rc->rc_error != 0) {
dead++;
if (c >= nparity)
dead_data++;
continue;
}
if (rc->rc_size == 0)
continue;
for (int lt = 0; lt < ntgts; lt++) {
if (rc->rc_devidx == ltgts[lt]) {
if (rc->rc_orig_data == NULL) {
rc->rc_orig_data =
abd_alloc_linear(
rc->rc_size, B_TRUE);
abd_copy(rc->rc_orig_data,
rc->rc_abd, rc->rc_size);
}
rc->rc_need_orig_restore = B_TRUE;
dead++;
if (c >= nparity)
dead_data++;
my_tgts[t++] = c;
break;
}
}
}
if (dead > nparity) {
/* reconstruction not possible */
raidz_restore_orig_data(rm);
return (EINVAL);
}
if (dead_data > 0)
vdev_raidz_reconstruct_row(rm, rr, my_tgts, t);
}
/* Check for success */
if (raidz_checksum_verify(zio) == 0) {
/* Reconstruction succeeded - report errors */
for (int i = 0; i < rm->rm_nrows; i++) {
raidz_row_t *rr = rm->rm_row[i];
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_need_orig_restore) {
/*
* Note: if this is a parity column,
* we don't really know if it's wrong.
* We need to let
* vdev_raidz_io_done_verified() check
* it, and if we set rc_error, it will
* think that it is a "known" error
* that doesn't need to be checked
* or corrected.
*/
if (rc->rc_error == 0 &&
c >= rr->rr_firstdatacol) {
raidz_checksum_error(zio,
rc, rc->rc_orig_data);
rc->rc_error =
SET_ERROR(ECKSUM);
}
rc->rc_need_orig_restore = B_FALSE;
}
}
vdev_raidz_io_done_verified(zio, rr);
}
zio_checksum_verified(zio);
return (0);
}
/* Reconstruction failed - restore original data */
raidz_restore_orig_data(rm);
return (ECKSUM);
}
/*
* Iterate over all combinations of N bad vdevs and attempt a reconstruction.
* Note that the algorithm below is non-optimal because it doesn't take into
* account how reconstruction is actually performed. For example, with
* triple-parity RAID-Z the reconstruction procedure is the same if column 4
* is targeted as invalid as if columns 1 and 4 are targeted since in both
* cases we'd only use parity information in column 0.
*
* The order that we find the various possible combinations of failed
* disks is dictated by these rules:
* - Examine each "slot" (the "i" in tgts[i])
* - Try to increment this slot (tgts[i] = tgts[i] + 1)
* - if we can't increment because it runs into the next slot,
* reset our slot to the minimum, and examine the next slot
*
* For example, with a 6-wide RAIDZ3, and no known errors (so we have to choose
* 3 columns to reconstruct), we will generate the following sequence:
*
* STATE ACTION
* 0 1 2 special case: skip since these are all parity
* 0 1 3 first slot: reset to 0; middle slot: increment to 2
* 0 2 3 first slot: increment to 1
* 1 2 3 first: reset to 0; middle: reset to 1; last: increment to 4
* 0 1 4 first: reset to 0; middle: increment to 2
* 0 2 4 first: increment to 1
* 1 2 4 first: reset to 0; middle: increment to 3
* 0 3 4 first: increment to 1
* 1 3 4 first: increment to 2
* 2 3 4 first: reset to 0; middle: reset to 1; last: increment to 5
* 0 1 5 first: reset to 0; middle: increment to 2
* 0 2 5 first: increment to 1
* 1 2 5 first: reset to 0; middle: increment to 3
* 0 3 5 first: increment to 1
* 1 3 5 first: increment to 2
* 2 3 5 first: reset to 0; middle: increment to 4
* 0 4 5 first: increment to 1
* 1 4 5 first: increment to 2
* 2 4 5 first: increment to 3
* 3 4 5 done
*
* This strategy works for dRAID but is less efficient when there are a large
* number of child vdevs and therefore permutations to check. Furthermore,
* since the raidz_map_t rows likely do not overlap reconstruction would be
* possible as long as there are no more than nparity data errors per row.
* These additional permutations are not currently checked but could be as
* a future improvement.
*/
static int
vdev_raidz_combrec(zio_t *zio)
{
int nparity = vdev_get_nparity(zio->io_vd);
raidz_map_t *rm = zio->io_vsd;
/* Check if there's enough data to attempt reconstrution. */
for (int i = 0; i < rm->rm_nrows; i++) {
raidz_row_t *rr = rm->rm_row[i];
int total_errors = 0;
for (int c = 0; c < rr->rr_cols; c++) {
if (rr->rr_col[c].rc_error)
total_errors++;
}
if (total_errors > nparity)
return (vdev_raidz_worst_error(rr));
}
for (int num_failures = 1; num_failures <= nparity; num_failures++) {
int tstore[VDEV_RAIDZ_MAXPARITY + 2];
int *ltgts = &tstore[1]; /* value is logical child ID */
/* Determine number of logical children, n */
int n = zio->io_vd->vdev_children;
ASSERT3U(num_failures, <=, nparity);
ASSERT3U(num_failures, <=, VDEV_RAIDZ_MAXPARITY);
/* Handle corner cases in combrec logic */
ltgts[-1] = -1;
for (int i = 0; i < num_failures; i++) {
ltgts[i] = i;
}
ltgts[num_failures] = n;
for (;;) {
int err = raidz_reconstruct(zio, ltgts, num_failures,
nparity);
if (err == EINVAL) {
/*
* Reconstruction not possible with this #
* failures; try more failures.
*/
break;
} else if (err == 0)
return (0);
/* Compute next targets to try */
for (int t = 0; ; t++) {
ASSERT3U(t, <, num_failures);
ltgts[t]++;
if (ltgts[t] == n) {
/* try more failures */
ASSERT3U(t, ==, num_failures - 1);
break;
}
ASSERT3U(ltgts[t], <, n);
ASSERT3U(ltgts[t], <=, ltgts[t + 1]);
/*
* If that spot is available, we're done here.
* Try the next combination.
*/
if (ltgts[t] != ltgts[t + 1])
break;
/*
* Otherwise, reset this tgt to the minimum,
* and move on to the next tgt.
*/
ltgts[t] = ltgts[t - 1] + 1;
ASSERT3U(ltgts[t], ==, t);
}
/* Increase the number of failures and keep trying. */
if (ltgts[num_failures - 1] == n)
break;
}
}
return (ECKSUM);
}
void
vdev_raidz_reconstruct(raidz_map_t *rm, const int *t, int nt)
{
for (uint64_t row = 0; row < rm->rm_nrows; row++) {
raidz_row_t *rr = rm->rm_row[row];
vdev_raidz_reconstruct_row(rm, rr, t, nt);
}
}
/*
* Complete a write IO operation on a RAIDZ VDev
*
* Outline:
* 1. Check for errors on the child IOs.
* 2. Return, setting an error code if too few child VDevs were written
* to reconstruct the data later. Note that partial writes are
* considered successful if they can be reconstructed at all.
*/
static void
vdev_raidz_io_done_write_impl(zio_t *zio, raidz_row_t *rr)
{
int total_errors = 0;
ASSERT3U(rr->rr_missingparity, <=, rr->rr_firstdatacol);
ASSERT3U(rr->rr_missingdata, <=, rr->rr_cols - rr->rr_firstdatacol);
ASSERT3U(zio->io_type, ==, ZIO_TYPE_WRITE);
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_error) {
ASSERT(rc->rc_error != ECKSUM); /* child has no bp */
total_errors++;
}
}
/*
* Treat partial writes as a success. If we couldn't write enough
* columns to reconstruct the data, the I/O failed. Otherwise,
* good enough.
*
* Now that we support write reallocation, it would be better
* to treat partial failure as real failure unless there are
* no non-degraded top-level vdevs left, and not update DTLs
* if we intend to reallocate.
*/
if (total_errors > rr->rr_firstdatacol) {
zio->io_error = zio_worst_error(zio->io_error,
vdev_raidz_worst_error(rr));
}
}
static void
vdev_raidz_io_done_reconstruct_known_missing(zio_t *zio, raidz_map_t *rm,
raidz_row_t *rr)
{
int parity_errors = 0;
int parity_untried = 0;
int data_errors = 0;
int total_errors = 0;
ASSERT3U(rr->rr_missingparity, <=, rr->rr_firstdatacol);
ASSERT3U(rr->rr_missingdata, <=, rr->rr_cols - rr->rr_firstdatacol);
ASSERT3U(zio->io_type, ==, ZIO_TYPE_READ);
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_error) {
ASSERT(rc->rc_error != ECKSUM); /* child has no bp */
if (c < rr->rr_firstdatacol)
parity_errors++;
else
data_errors++;
total_errors++;
} else if (c < rr->rr_firstdatacol && !rc->rc_tried) {
parity_untried++;
}
}
/*
* If there were data errors and the number of errors we saw was
* correctable -- less than or equal to the number of parity disks read
* -- reconstruct based on the missing data.
*/
if (data_errors != 0 &&
total_errors <= rr->rr_firstdatacol - parity_untried) {
/*
* We either attempt to read all the parity columns or
* none of them. If we didn't try to read parity, we
* wouldn't be here in the correctable case. There must
* also have been fewer parity errors than parity
* columns or, again, we wouldn't be in this code path.
*/
ASSERT(parity_untried == 0);
ASSERT(parity_errors < rr->rr_firstdatacol);
/*
* Identify the data columns that reported an error.
*/
int n = 0;
int tgts[VDEV_RAIDZ_MAXPARITY];
for (int c = rr->rr_firstdatacol; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_error != 0) {
ASSERT(n < VDEV_RAIDZ_MAXPARITY);
tgts[n++] = c;
}
}
ASSERT(rr->rr_firstdatacol >= n);
vdev_raidz_reconstruct_row(rm, rr, tgts, n);
}
}
/*
* Return the number of reads issued.
*/
static int
vdev_raidz_read_all(zio_t *zio, raidz_row_t *rr)
{
vdev_t *vd = zio->io_vd;
int nread = 0;
rr->rr_missingdata = 0;
rr->rr_missingparity = 0;
/*
* If this rows contains empty sectors which are not required
* for a normal read then allocate an ABD for them now so they
* may be read, verified, and any needed repairs performed.
*/
if (rr->rr_nempty && rr->rr_abd_empty == NULL)
vdev_draid_map_alloc_empty(zio, rr);
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_tried || rc->rc_size == 0)
continue;
zio_nowait(zio_vdev_child_io(zio, NULL,
vd->vdev_child[rc->rc_devidx],
rc->rc_offset, rc->rc_abd, rc->rc_size,
zio->io_type, zio->io_priority, 0,
vdev_raidz_child_done, rc));
nread++;
}
return (nread);
}
/*
* We're here because either there were too many errors to even attempt
* reconstruction (total_errors == rm_first_datacol), or vdev_*_combrec()
* failed. In either case, there is enough bad data to prevent reconstruction.
* Start checksum ereports for all children which haven't failed.
*/
static void
vdev_raidz_io_done_unrecoverable(zio_t *zio)
{
raidz_map_t *rm = zio->io_vsd;
for (int i = 0; i < rm->rm_nrows; i++) {
raidz_row_t *rr = rm->rm_row[i];
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
vdev_t *cvd = zio->io_vd->vdev_child[rc->rc_devidx];
if (rc->rc_error != 0)
continue;
zio_bad_cksum_t zbc;
zbc.zbc_has_cksum = 0;
zbc.zbc_injected = rm->rm_ecksuminjected;
(void) zfs_ereport_start_checksum(zio->io_spa,
cvd, &zio->io_bookmark, zio, rc->rc_offset,
rc->rc_size, &zbc);
mutex_enter(&cvd->vdev_stat_lock);
cvd->vdev_stat.vs_checksum_errors++;
mutex_exit(&cvd->vdev_stat_lock);
}
}
}
void
vdev_raidz_io_done(zio_t *zio)
{
raidz_map_t *rm = zio->io_vsd;
if (zio->io_type == ZIO_TYPE_WRITE) {
for (int i = 0; i < rm->rm_nrows; i++) {
vdev_raidz_io_done_write_impl(zio, rm->rm_row[i]);
}
} else {
for (int i = 0; i < rm->rm_nrows; i++) {
raidz_row_t *rr = rm->rm_row[i];
vdev_raidz_io_done_reconstruct_known_missing(zio,
rm, rr);
}
if (raidz_checksum_verify(zio) == 0) {
for (int i = 0; i < rm->rm_nrows; i++) {
raidz_row_t *rr = rm->rm_row[i];
vdev_raidz_io_done_verified(zio, rr);
}
zio_checksum_verified(zio);
} else {
/*
* A sequential resilver has no checksum which makes
* combinatoral reconstruction impossible. This code
* path is unreachable since raidz_checksum_verify()
* has no checksum to verify and must succeed.
*/
ASSERT3U(zio->io_priority, !=, ZIO_PRIORITY_REBUILD);
/*
* This isn't a typical situation -- either we got a
* read error or a child silently returned bad data.
* Read every block so we can try again with as much
* data and parity as we can track down. If we've
* already been through once before, all children will
* be marked as tried so we'll proceed to combinatorial
* reconstruction.
*/
int nread = 0;
for (int i = 0; i < rm->rm_nrows; i++) {
nread += vdev_raidz_read_all(zio,
rm->rm_row[i]);
}
if (nread != 0) {
/*
* Normally our stage is VDEV_IO_DONE, but if
* we've already called redone(), it will have
* changed to VDEV_IO_START, in which case we
* don't want to call redone() again.
*/
if (zio->io_stage != ZIO_STAGE_VDEV_IO_START)
zio_vdev_io_redone(zio);
return;
}
zio->io_error = vdev_raidz_combrec(zio);
if (zio->io_error == ECKSUM &&
!(zio->io_flags & ZIO_FLAG_SPECULATIVE)) {
vdev_raidz_io_done_unrecoverable(zio);
}
}
}
}
static void
vdev_raidz_state_change(vdev_t *vd, int faulted, int degraded)
{
vdev_raidz_t *vdrz = vd->vdev_tsd;
if (faulted > vdrz->vd_nparity)
vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
VDEV_AUX_NO_REPLICAS);
else if (degraded + faulted != 0)
vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
else
vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
}
/*
* Determine if any portion of the provided block resides on a child vdev
* with a dirty DTL and therefore needs to be resilvered. The function
* assumes that at least one DTL is dirty which implies that full stripe
* width blocks must be resilvered.
*/
static boolean_t
vdev_raidz_need_resilver(vdev_t *vd, const dva_t *dva, size_t psize,
uint64_t phys_birth)
{
vdev_raidz_t *vdrz = vd->vdev_tsd;
uint64_t dcols = vd->vdev_children;
uint64_t nparity = vdrz->vd_nparity;
uint64_t ashift = vd->vdev_top->vdev_ashift;
/* The starting RAIDZ (parent) vdev sector of the block. */
uint64_t b = DVA_GET_OFFSET(dva) >> ashift;
/* The zio's size in units of the vdev's minimum sector size. */
uint64_t s = ((psize - 1) >> ashift) + 1;
/* The first column for this stripe. */
uint64_t f = b % dcols;
/* Unreachable by sequential resilver. */
ASSERT3U(phys_birth, !=, TXG_UNKNOWN);
if (!vdev_dtl_contains(vd, DTL_PARTIAL, phys_birth, 1))
return (B_FALSE);
if (s + nparity >= dcols)
return (B_TRUE);
for (uint64_t c = 0; c < s + nparity; c++) {
uint64_t devidx = (f + c) % dcols;
vdev_t *cvd = vd->vdev_child[devidx];
/*
* dsl_scan_need_resilver() already checked vd with
* vdev_dtl_contains(). So here just check cvd with
* vdev_dtl_empty(), cheaper and a good approximation.
*/
if (!vdev_dtl_empty(cvd, DTL_PARTIAL))
return (B_TRUE);
}
return (B_FALSE);
}
static void
vdev_raidz_xlate(vdev_t *cvd, const range_seg64_t *logical_rs,
range_seg64_t *physical_rs, range_seg64_t *remain_rs)
{
vdev_t *raidvd = cvd->vdev_parent;
ASSERT(raidvd->vdev_ops == &vdev_raidz_ops);
uint64_t width = raidvd->vdev_children;
uint64_t tgt_col = cvd->vdev_id;
uint64_t ashift = raidvd->vdev_top->vdev_ashift;
/* make sure the offsets are block-aligned */
ASSERT0(logical_rs->rs_start % (1 << ashift));
ASSERT0(logical_rs->rs_end % (1 << ashift));
uint64_t b_start = logical_rs->rs_start >> ashift;
uint64_t b_end = logical_rs->rs_end >> ashift;
uint64_t start_row = 0;
if (b_start > tgt_col) /* avoid underflow */
start_row = ((b_start - tgt_col - 1) / width) + 1;
uint64_t end_row = 0;
if (b_end > tgt_col)
end_row = ((b_end - tgt_col - 1) / width) + 1;
physical_rs->rs_start = start_row << ashift;
physical_rs->rs_end = end_row << ashift;
ASSERT3U(physical_rs->rs_start, <=, logical_rs->rs_start);
ASSERT3U(physical_rs->rs_end - physical_rs->rs_start, <=,
logical_rs->rs_end - logical_rs->rs_start);
}
/*
* Initialize private RAIDZ specific fields from the nvlist.
*/
static int
vdev_raidz_init(spa_t *spa, nvlist_t *nv, void **tsd)
{
vdev_raidz_t *vdrz;
uint64_t nparity;
uint_t children;
nvlist_t **child;
int error = nvlist_lookup_nvlist_array(nv,
ZPOOL_CONFIG_CHILDREN, &child, &children);
if (error != 0)
return (SET_ERROR(EINVAL));
if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_NPARITY, &nparity) == 0) {
if (nparity == 0 || nparity > VDEV_RAIDZ_MAXPARITY)
return (SET_ERROR(EINVAL));
/*
* Previous versions could only support 1 or 2 parity
* device.
*/
if (nparity > 1 && spa_version(spa) < SPA_VERSION_RAIDZ2)
return (SET_ERROR(EINVAL));
else if (nparity > 2 && spa_version(spa) < SPA_VERSION_RAIDZ3)
return (SET_ERROR(EINVAL));
} else {
/*
* We require the parity to be specified for SPAs that
* support multiple parity levels.
*/
if (spa_version(spa) >= SPA_VERSION_RAIDZ2)
return (SET_ERROR(EINVAL));
/*
* Otherwise, we default to 1 parity device for RAID-Z.
*/
nparity = 1;
}
vdrz = kmem_zalloc(sizeof (*vdrz), KM_SLEEP);
vdrz->vd_logical_width = children;
vdrz->vd_nparity = nparity;
*tsd = vdrz;
return (0);
}
static void
vdev_raidz_fini(vdev_t *vd)
{
kmem_free(vd->vdev_tsd, sizeof (vdev_raidz_t));
}
/*
* Add RAIDZ specific fields to the config nvlist.
*/
static void
vdev_raidz_config_generate(vdev_t *vd, nvlist_t *nv)
{
ASSERT3P(vd->vdev_ops, ==, &vdev_raidz_ops);
vdev_raidz_t *vdrz = vd->vdev_tsd;
/*
* Make sure someone hasn't managed to sneak a fancy new vdev
* into a crufty old storage pool.
*/
ASSERT(vdrz->vd_nparity == 1 ||
(vdrz->vd_nparity <= 2 &&
spa_version(vd->vdev_spa) >= SPA_VERSION_RAIDZ2) ||
(vdrz->vd_nparity <= 3 &&
spa_version(vd->vdev_spa) >= SPA_VERSION_RAIDZ3));
/*
* Note that we'll add these even on storage pools where they
* aren't strictly required -- older software will just ignore
* it.
*/
fnvlist_add_uint64(nv, ZPOOL_CONFIG_NPARITY, vdrz->vd_nparity);
}
static uint64_t
vdev_raidz_nparity(vdev_t *vd)
{
vdev_raidz_t *vdrz = vd->vdev_tsd;
return (vdrz->vd_nparity);
}
static uint64_t
vdev_raidz_ndisks(vdev_t *vd)
{
return (vd->vdev_children);
}
vdev_ops_t vdev_raidz_ops = {
.vdev_op_init = vdev_raidz_init,
.vdev_op_fini = vdev_raidz_fini,
.vdev_op_open = vdev_raidz_open,
.vdev_op_close = vdev_raidz_close,
.vdev_op_asize = vdev_raidz_asize,
.vdev_op_min_asize = vdev_raidz_min_asize,
.vdev_op_min_alloc = NULL,
.vdev_op_io_start = vdev_raidz_io_start,
.vdev_op_io_done = vdev_raidz_io_done,
.vdev_op_state_change = vdev_raidz_state_change,
.vdev_op_need_resilver = vdev_raidz_need_resilver,
.vdev_op_hold = NULL,
.vdev_op_rele = NULL,
.vdev_op_remap = NULL,
.vdev_op_xlate = vdev_raidz_xlate,
.vdev_op_rebuild_asize = NULL,
.vdev_op_metaslab_init = NULL,
.vdev_op_config_generate = vdev_raidz_config_generate,
.vdev_op_nparity = vdev_raidz_nparity,
.vdev_op_ndisks = vdev_raidz_ndisks,
.vdev_op_type = VDEV_TYPE_RAIDZ, /* name of this vdev type */
.vdev_op_leaf = B_FALSE /* not a leaf vdev */
};
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