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mirror_zfs/module/zfs/vdev_raidz.c
Alexander Motin 37f6845c6f
Improve too large physical ashift handling 
When iterating through children physical ashifts for vdev, prefer
ones above the maximum logical ashift, that we can actually use,
but within the administrator defined maximum.

When selecting top-level vdev ashift, do not set it to the defined
maximum in case physical ashift is even higher, but just ignore one.
Using the maximum does not prevent misaligned writes, but reduces
space efficiency.  Since ZFS tries to write data sequentially and
aggregates the writes, in many cases large misanigned writes may be
not as bad as the space penalty otherwise.

Allow internal physical ashifts for vdevs higher than SHIFT_MAX.
May be one day allocator or aggregation could benefit from that.

Reduce zfs_vdev_max_auto_ashift default from 16 (64KB) to 14 (16KB),
so that ZFS may still use bigger ashifts up to SHIFT_MAX (64KB),
but only if it really has to or explicitly told to, but not as an
"optimization".

There are some read-intensive NVMe SSDs that report Preferred Write
Alignment of 64KB, and attempt to build RAIDZ2 of those leads to a
space inefficiency that can't be justified.  Instead these changes
make ZFS fall back to logical ashift of 12 (4KB) by default and
only warn user that it may be suboptimal for performance.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by:	Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Closes #13798
2022-09-08 10:30:53 -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 https://opensource.org/licenses/CDDL-1.0.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2020 by Delphix. All rights reserved.
* Copyright (c) 2016 Gvozden Nešković. All rights reserved.
*/
#include <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);
}
}
static int
vdev_raidz_reconst_p_func(void *dbuf, void *sbuf, size_t size, void *private)
{
(void) private;
uint64_t *dst = dbuf;
uint64_t *src = sbuf;
int cnt = size / sizeof (src[0]);
for (int i = 0; i < cnt; i++) {
dst[i] ^= src[i];
}
return (0);
}
static int
vdev_raidz_reconst_q_pre_func(void *dbuf, void *sbuf, size_t size,
void *private)
{
(void) private;
uint64_t *dst = dbuf;
uint64_t *src = sbuf;
uint64_t mask;
int cnt = size / sizeof (dst[0]);
for (int i = 0; i < cnt; i++, dst++, src++) {
VDEV_RAIDZ_64MUL_2(*dst, mask);
*dst ^= *src;
}
return (0);
}
static int
vdev_raidz_reconst_q_pre_tail_func(void *buf, size_t size, void *private)
{
(void) private;
uint64_t *dst = buf;
uint64_t mask;
int cnt = size / sizeof (dst[0]);
for (int i = 0; i < cnt; i++, dst++) {
/* same operation as vdev_raidz_reconst_q_pre_func() on dst */
VDEV_RAIDZ_64MUL_2(*dst, mask);
}
return (0);
}
struct reconst_q_struct {
uint64_t *q;
int exp;
};
static int
vdev_raidz_reconst_q_post_func(void *buf, size_t size, void *private)
{
struct reconst_q_struct *rq = private;
uint64_t *dst = buf;
int cnt = size / sizeof (dst[0]);
for (int i = 0; i < cnt; i++, dst++, rq->q++) {
int j;
uint8_t *b;
*dst ^= *rq->q;
for (j = 0, b = (uint8_t *)dst; j < 8; j++, b++) {
*b = vdev_raidz_exp2(*b, rq->exp);
}
}
return (0);
}
struct reconst_pq_struct {
uint8_t *p;
uint8_t *q;
uint8_t *pxy;
uint8_t *qxy;
int aexp;
int bexp;
};
static int
vdev_raidz_reconst_pq_func(void *xbuf, void *ybuf, size_t size, void *private)
{
struct reconst_pq_struct *rpq = private;
uint8_t *xd = xbuf;
uint8_t *yd = ybuf;
for (int i = 0; i < size;
i++, rpq->p++, rpq->q++, rpq->pxy++, rpq->qxy++, xd++, yd++) {
*xd = vdev_raidz_exp2(*rpq->p ^ *rpq->pxy, rpq->aexp) ^
vdev_raidz_exp2(*rpq->q ^ *rpq->qxy, rpq->bexp);
*yd = *rpq->p ^ *rpq->pxy ^ *xd;
}
return (0);
}
static int
vdev_raidz_reconst_pq_tail_func(void *xbuf, size_t size, void *private)
{
struct reconst_pq_struct *rpq = private;
uint8_t *xd = xbuf;
for (int i = 0; i < size;
i++, rpq->p++, rpq->q++, rpq->pxy++, rpq->qxy++, xd++) {
/* same operation as vdev_raidz_reconst_pq_func() on xd */
*xd = vdev_raidz_exp2(*rpq->p ^ *rpq->pxy, rpq->aexp) ^
vdev_raidz_exp2(*rpq->q ^ *rpq->qxy, rpq->bexp);
}
return (0);
}
static void
vdev_raidz_reconstruct_p(raidz_row_t *rr, int *tgts, int ntgts)
{
int x = tgts[0];
abd_t *dst, *src;
ASSERT3U(ntgts, ==, 1);
ASSERT3U(x, >=, rr->rr_firstdatacol);
ASSERT3U(x, <, rr->rr_cols);
ASSERT3U(rr->rr_col[x].rc_size, <=, rr->rr_col[VDEV_RAIDZ_P].rc_size);
src = rr->rr_col[VDEV_RAIDZ_P].rc_abd;
dst = rr->rr_col[x].rc_abd;
abd_copy_from_buf(dst, abd_to_buf(src), rr->rr_col[x].rc_size);
for (int c = rr->rr_firstdatacol; c < rr->rr_cols; c++) {
uint64_t size = MIN(rr->rr_col[x].rc_size,
rr->rr_col[c].rc_size);
src = rr->rr_col[c].rc_abd;
if (c == x)
continue;
(void) abd_iterate_func2(dst, src, 0, 0, size,
vdev_raidz_reconst_p_func, NULL);
}
}
static void
vdev_raidz_reconstruct_q(raidz_row_t *rr, int *tgts, int ntgts)
{
int x = tgts[0];
int c, exp;
abd_t *dst, *src;
ASSERT(ntgts == 1);
ASSERT(rr->rr_col[x].rc_size <= rr->rr_col[VDEV_RAIDZ_Q].rc_size);
for (c = rr->rr_firstdatacol; c < rr->rr_cols; c++) {
uint64_t size = (c == x) ? 0 : MIN(rr->rr_col[x].rc_size,
rr->rr_col[c].rc_size);
src = rr->rr_col[c].rc_abd;
dst = rr->rr_col[x].rc_abd;
if (c == rr->rr_firstdatacol) {
abd_copy(dst, src, size);
if (rr->rr_col[x].rc_size > size) {
abd_zero_off(dst, size,
rr->rr_col[x].rc_size - size);
}
} else {
ASSERT3U(size, <=, rr->rr_col[x].rc_size);
(void) abd_iterate_func2(dst, src, 0, 0, size,
vdev_raidz_reconst_q_pre_func, NULL);
(void) abd_iterate_func(dst,
size, rr->rr_col[x].rc_size - size,
vdev_raidz_reconst_q_pre_tail_func, NULL);
}
}
src = rr->rr_col[VDEV_RAIDZ_Q].rc_abd;
dst = rr->rr_col[x].rc_abd;
exp = 255 - (rr->rr_cols - 1 - x);
struct reconst_q_struct rq = { abd_to_buf(src), exp };
(void) abd_iterate_func(dst, 0, rr->rr_col[x].rc_size,
vdev_raidz_reconst_q_post_func, &rq);
}
static void
vdev_raidz_reconstruct_pq(raidz_row_t *rr, int *tgts, int ntgts)
{
uint8_t *p, *q, *pxy, *qxy, tmp, a, b, aexp, bexp;
abd_t *pdata, *qdata;
uint64_t xsize, ysize;
int x = tgts[0];
int y = tgts[1];
abd_t *xd, *yd;
ASSERT(ntgts == 2);
ASSERT(x < y);
ASSERT(x >= rr->rr_firstdatacol);
ASSERT(y < rr->rr_cols);
ASSERT(rr->rr_col[x].rc_size >= rr->rr_col[y].rc_size);
/*
* Move the parity data aside -- we're going to compute parity as
* though columns x and y were full of zeros -- Pxy and Qxy. We want to
* reuse the parity generation mechanism without trashing the actual
* parity so we make those columns appear to be full of zeros by
* setting their lengths to zero.
*/
pdata = rr->rr_col[VDEV_RAIDZ_P].rc_abd;
qdata = rr->rr_col[VDEV_RAIDZ_Q].rc_abd;
xsize = rr->rr_col[x].rc_size;
ysize = rr->rr_col[y].rc_size;
rr->rr_col[VDEV_RAIDZ_P].rc_abd =
abd_alloc_linear(rr->rr_col[VDEV_RAIDZ_P].rc_size, B_TRUE);
rr->rr_col[VDEV_RAIDZ_Q].rc_abd =
abd_alloc_linear(rr->rr_col[VDEV_RAIDZ_Q].rc_size, B_TRUE);
rr->rr_col[x].rc_size = 0;
rr->rr_col[y].rc_size = 0;
vdev_raidz_generate_parity_pq(rr);
rr->rr_col[x].rc_size = xsize;
rr->rr_col[y].rc_size = ysize;
p = abd_to_buf(pdata);
q = abd_to_buf(qdata);
pxy = abd_to_buf(rr->rr_col[VDEV_RAIDZ_P].rc_abd);
qxy = abd_to_buf(rr->rr_col[VDEV_RAIDZ_Q].rc_abd);
xd = rr->rr_col[x].rc_abd;
yd = rr->rr_col[y].rc_abd;
/*
* We now have:
* Pxy = P + D_x + D_y
* Qxy = Q + 2^(ndevs - 1 - x) * D_x + 2^(ndevs - 1 - y) * D_y
*
* We can then solve for D_x:
* D_x = A * (P + Pxy) + B * (Q + Qxy)
* where
* A = 2^(x - y) * (2^(x - y) + 1)^-1
* B = 2^(ndevs - 1 - x) * (2^(x - y) + 1)^-1
*
* With D_x in hand, we can easily solve for D_y:
* D_y = P + Pxy + D_x
*/
a = vdev_raidz_pow2[255 + x - y];
b = vdev_raidz_pow2[255 - (rr->rr_cols - 1 - x)];
tmp = 255 - vdev_raidz_log2[a ^ 1];
aexp = vdev_raidz_log2[vdev_raidz_exp2(a, tmp)];
bexp = vdev_raidz_log2[vdev_raidz_exp2(b, tmp)];
ASSERT3U(xsize, >=, ysize);
struct reconst_pq_struct rpq = { p, q, pxy, qxy, aexp, bexp };
(void) abd_iterate_func2(xd, yd, 0, 0, ysize,
vdev_raidz_reconst_pq_func, &rpq);
(void) abd_iterate_func(xd, ysize, xsize - ysize,
vdev_raidz_reconst_pq_tail_func, &rpq);
abd_free(rr->rr_col[VDEV_RAIDZ_P].rc_abd);
abd_free(rr->rr_col[VDEV_RAIDZ_Q].rc_abd);
/*
* Restore the saved parity data.
*/
rr->rr_col[VDEV_RAIDZ_P].rc_abd = pdata;
rr->rr_col[VDEV_RAIDZ_Q].rc_abd = qdata;
}
/*
* In the general case of reconstruction, we must solve the system of linear
* equations defined by the coefficients used to generate parity as well as
* the contents of the data and parity disks. This can be expressed with
* vectors for the original data (D) and the actual data (d) and parity (p)
* and a matrix composed of the identity matrix (I) and a dispersal matrix (V):
*
* __ __ __ __
* | | __ __ | p_0 |
* | V | | D_0 | | p_m-1 |
* | | x | : | = | d_0 |
* | I | | D_n-1 | | : |
* | | ~~ ~~ | d_n-1 |
* ~~ ~~ ~~ ~~
*
* I is simply a square identity matrix of size n, and V is a vandermonde
* matrix defined by the coefficients we chose for the various parity columns
* (1, 2, 4). Note that these values were chosen both for simplicity, speedy
* computation as well as linear separability.
*
* __ __ __ __
* | 1 .. 1 1 1 | | p_0 |
* | 2^n-1 .. 4 2 1 | __ __ | : |
* | 4^n-1 .. 16 4 1 | | D_0 | | p_m-1 |
* | 1 .. 0 0 0 | | D_1 | | d_0 |
* | 0 .. 0 0 0 | x | D_2 | = | d_1 |
* | : : : : | | : | | d_2 |
* | 0 .. 1 0 0 | | D_n-1 | | : |
* | 0 .. 0 1 0 | ~~ ~~ | : |
* | 0 .. 0 0 1 | | d_n-1 |
* ~~ ~~ ~~ ~~
*
* Note that I, V, d, and p are known. To compute D, we must invert the
* matrix and use the known data and parity values to reconstruct the unknown
* data values. We begin by removing the rows in V|I and d|p that correspond
* to failed or missing columns; we then make V|I square (n x n) and d|p
* sized n by removing rows corresponding to unused parity from the bottom up
* to generate (V|I)' and (d|p)'. We can then generate the inverse of (V|I)'
* using Gauss-Jordan elimination. In the example below we use m=3 parity
* columns, n=8 data columns, with errors in d_1, d_2, and p_1:
* __ __
* | 1 1 1 1 1 1 1 1 |
* | 128 64 32 16 8 4 2 1 | <-----+-+-- missing disks
* | 19 205 116 29 64 16 4 1 | / /
* | 1 0 0 0 0 0 0 0 | / /
* | 0 1 0 0 0 0 0 0 | <--' /
* (V|I) = | 0 0 1 0 0 0 0 0 | <---'
* | 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 |
* ~~ ~~
* __ __
* | 1 1 1 1 1 1 1 1 |
* | 128 64 32 16 8 4 2 1 |
* | 19 205 116 29 64 16 4 1 |
* | 1 0 0 0 0 0 0 0 |
* | 0 1 0 0 0 0 0 0 |
* (V|I)' = | 0 0 1 0 0 0 0 0 |
* | 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 |
* ~~ ~~
*
* Here we employ Gauss-Jordan elimination to find the inverse of (V|I)'. We
* have carefully chosen the seed values 1, 2, and 4 to ensure that this
* matrix is not singular.
* __ __
* | 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 |
* | 19 205 116 29 64 16 4 1 0 1 0 0 0 0 0 0 |
* | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 |
* | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 |
* ~~ ~~
* __ __
* | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 |
* | 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 |
* | 19 205 116 29 64 16 4 1 0 1 0 0 0 0 0 0 |
* | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 |
* ~~ ~~
* __ __
* | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 |
* | 0 1 1 0 0 0 0 0 1 0 1 1 1 1 1 1 |
* | 0 205 116 0 0 0 0 0 0 1 19 29 64 16 4 1 |
* | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 |
* ~~ ~~
* __ __
* | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 |
* | 0 1 1 0 0 0 0 0 1 0 1 1 1 1 1 1 |
* | 0 0 185 0 0 0 0 0 205 1 222 208 141 221 201 204 |
* | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 |
* ~~ ~~
* __ __
* | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 |
* | 0 1 1 0 0 0 0 0 1 0 1 1 1 1 1 1 |
* | 0 0 1 0 0 0 0 0 166 100 4 40 158 168 216 209 |
* | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 |
* ~~ ~~
* __ __
* | 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 |
* | 0 1 0 0 0 0 0 0 167 100 5 41 159 169 217 208 |
* | 0 0 1 0 0 0 0 0 166 100 4 40 158 168 216 209 |
* | 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 |
* ~~ ~~
* __ __
* | 0 0 1 0 0 0 0 0 |
* | 167 100 5 41 159 169 217 208 |
* | 166 100 4 40 158 168 216 209 |
* (V|I)'^-1 = | 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 |
* ~~ ~~
*
* We can then simply compute D = (V|I)'^-1 x (d|p)' to discover the values
* of the missing data.
*
* As is apparent from the example above, the only non-trivial rows in the
* inverse matrix correspond to the data disks that we're trying to
* reconstruct. Indeed, those are the only rows we need as the others would
* only be useful for reconstructing data known or assumed to be valid. For
* that reason, we only build the coefficients in the rows that correspond to
* targeted columns.
*/
static void
vdev_raidz_matrix_init(raidz_row_t *rr, int n, int nmap, int *map,
uint8_t **rows)
{
int i, j;
int pow;
ASSERT(n == rr->rr_cols - rr->rr_firstdatacol);
/*
* Fill in the missing rows of interest.
*/
for (i = 0; i < nmap; i++) {
ASSERT3S(0, <=, map[i]);
ASSERT3S(map[i], <=, 2);
pow = map[i] * n;
if (pow > 255)
pow -= 255;
ASSERT(pow <= 255);
for (j = 0; j < n; j++) {
pow -= map[i];
if (pow < 0)
pow += 255;
rows[i][j] = vdev_raidz_pow2[pow];
}
}
}
static void
vdev_raidz_matrix_invert(raidz_row_t *rr, int n, int nmissing, int *missing,
uint8_t **rows, uint8_t **invrows, const uint8_t *used)
{
int i, j, ii, jj;
uint8_t log;
/*
* Assert that the first nmissing entries from the array of used
* columns correspond to parity columns and that subsequent entries
* correspond to data columns.
*/
for (i = 0; i < nmissing; i++) {
ASSERT3S(used[i], <, rr->rr_firstdatacol);
}
for (; i < n; i++) {
ASSERT3S(used[i], >=, rr->rr_firstdatacol);
}
/*
* First initialize the storage where we'll compute the inverse rows.
*/
for (i = 0; i < nmissing; i++) {
for (j = 0; j < n; j++) {
invrows[i][j] = (i == j) ? 1 : 0;
}
}
/*
* Subtract all trivial rows from the rows of consequence.
*/
for (i = 0; i < nmissing; i++) {
for (j = nmissing; j < n; j++) {
ASSERT3U(used[j], >=, rr->rr_firstdatacol);
jj = used[j] - rr->rr_firstdatacol;
ASSERT3S(jj, <, n);
invrows[i][j] = rows[i][jj];
rows[i][jj] = 0;
}
}
/*
* For each of the rows of interest, we must normalize it and subtract
* a multiple of it from the other rows.
*/
for (i = 0; i < nmissing; i++) {
for (j = 0; j < missing[i]; j++) {
ASSERT0(rows[i][j]);
}
ASSERT3U(rows[i][missing[i]], !=, 0);
/*
* Compute the inverse of the first element and multiply each
* element in the row by that value.
*/
log = 255 - vdev_raidz_log2[rows[i][missing[i]]];
for (j = 0; j < n; j++) {
rows[i][j] = vdev_raidz_exp2(rows[i][j], log);
invrows[i][j] = vdev_raidz_exp2(invrows[i][j], log);
}
for (ii = 0; ii < nmissing; ii++) {
if (i == ii)
continue;
ASSERT3U(rows[ii][missing[i]], !=, 0);
log = vdev_raidz_log2[rows[ii][missing[i]]];
for (j = 0; j < n; j++) {
rows[ii][j] ^=
vdev_raidz_exp2(rows[i][j], log);
invrows[ii][j] ^=
vdev_raidz_exp2(invrows[i][j], log);
}
}
}
/*
* Verify that the data that is left in the rows are properly part of
* an identity matrix.
*/
for (i = 0; i < nmissing; i++) {
for (j = 0; j < n; j++) {
if (j == missing[i]) {
ASSERT3U(rows[i][j], ==, 1);
} else {
ASSERT0(rows[i][j]);
}
}
}
}
static void
vdev_raidz_matrix_reconstruct(raidz_row_t *rr, int n, int nmissing,
int *missing, uint8_t **invrows, const uint8_t *used)
{
int i, j, x, cc, c;
uint8_t *src;
uint64_t ccount;
uint8_t *dst[VDEV_RAIDZ_MAXPARITY] = { NULL };
uint64_t dcount[VDEV_RAIDZ_MAXPARITY] = { 0 };
uint8_t log = 0;
uint8_t val;
int ll;
uint8_t *invlog[VDEV_RAIDZ_MAXPARITY];
uint8_t *p, *pp;
size_t psize;
psize = sizeof (invlog[0][0]) * n * nmissing;
p = kmem_alloc(psize, KM_SLEEP);
for (pp = p, i = 0; i < nmissing; i++) {
invlog[i] = pp;
pp += n;
}
for (i = 0; i < nmissing; i++) {
for (j = 0; j < n; j++) {
ASSERT3U(invrows[i][j], !=, 0);
invlog[i][j] = vdev_raidz_log2[invrows[i][j]];
}
}
for (i = 0; i < n; i++) {
c = used[i];
ASSERT3U(c, <, rr->rr_cols);
ccount = rr->rr_col[c].rc_size;
ASSERT(ccount >= rr->rr_col[missing[0]].rc_size || i > 0);
if (ccount == 0)
continue;
src = abd_to_buf(rr->rr_col[c].rc_abd);
for (j = 0; j < nmissing; j++) {
cc = missing[j] + rr->rr_firstdatacol;
ASSERT3U(cc, >=, rr->rr_firstdatacol);
ASSERT3U(cc, <, rr->rr_cols);
ASSERT3U(cc, !=, c);
dcount[j] = rr->rr_col[cc].rc_size;
if (dcount[j] != 0)
dst[j] = abd_to_buf(rr->rr_col[cc].rc_abd);
}
for (x = 0; x < ccount; x++, src++) {
if (*src != 0)
log = vdev_raidz_log2[*src];
for (cc = 0; cc < nmissing; cc++) {
if (x >= dcount[cc])
continue;
if (*src == 0) {
val = 0;
} else {
if ((ll = log + invlog[cc][i]) >= 255)
ll -= 255;
val = vdev_raidz_pow2[ll];
}
if (i == 0)
dst[cc][x] = val;
else
dst[cc][x] ^= val;
}
}
}
kmem_free(p, psize);
}
static void
vdev_raidz_reconstruct_general(raidz_row_t *rr, int *tgts, int ntgts)
{
int n, i, c, t, tt;
int nmissing_rows;
int missing_rows[VDEV_RAIDZ_MAXPARITY];
int parity_map[VDEV_RAIDZ_MAXPARITY];
uint8_t *p, *pp;
size_t psize;
uint8_t *rows[VDEV_RAIDZ_MAXPARITY];
uint8_t *invrows[VDEV_RAIDZ_MAXPARITY];
uint8_t *used;
abd_t **bufs = NULL;
/*
* Matrix reconstruction can't use scatter ABDs yet, so we allocate
* temporary linear ABDs if any non-linear ABDs are found.
*/
for (i = rr->rr_firstdatacol; i < rr->rr_cols; i++) {
if (!abd_is_linear(rr->rr_col[i].rc_abd)) {
bufs = kmem_alloc(rr->rr_cols * sizeof (abd_t *),
KM_PUSHPAGE);
for (c = rr->rr_firstdatacol; c < rr->rr_cols; c++) {
raidz_col_t *col = &rr->rr_col[c];
bufs[c] = col->rc_abd;
if (bufs[c] != NULL) {
col->rc_abd = abd_alloc_linear(
col->rc_size, B_TRUE);
abd_copy(col->rc_abd, bufs[c],
col->rc_size);
}
}
break;
}
}
n = rr->rr_cols - rr->rr_firstdatacol;
/*
* Figure out which data columns are missing.
*/
nmissing_rows = 0;
for (t = 0; t < ntgts; t++) {
if (tgts[t] >= rr->rr_firstdatacol) {
missing_rows[nmissing_rows++] =
tgts[t] - rr->rr_firstdatacol;
}
}
/*
* Figure out which parity columns to use to help generate the missing
* data columns.
*/
for (tt = 0, c = 0, i = 0; i < nmissing_rows; c++) {
ASSERT(tt < ntgts);
ASSERT(c < rr->rr_firstdatacol);
/*
* Skip any targeted parity columns.
*/
if (c == tgts[tt]) {
tt++;
continue;
}
parity_map[i] = c;
i++;
}
psize = (sizeof (rows[0][0]) + sizeof (invrows[0][0])) *
nmissing_rows * n + sizeof (used[0]) * n;
p = kmem_alloc(psize, KM_SLEEP);
for (pp = p, i = 0; i < nmissing_rows; i++) {
rows[i] = pp;
pp += n;
invrows[i] = pp;
pp += n;
}
used = pp;
for (i = 0; i < nmissing_rows; i++) {
used[i] = parity_map[i];
}
for (tt = 0, c = rr->rr_firstdatacol; c < rr->rr_cols; c++) {
if (tt < nmissing_rows &&
c == missing_rows[tt] + rr->rr_firstdatacol) {
tt++;
continue;
}
ASSERT3S(i, <, n);
used[i] = c;
i++;
}
/*
* Initialize the interesting rows of the matrix.
*/
vdev_raidz_matrix_init(rr, n, nmissing_rows, parity_map, rows);
/*
* Invert the matrix.
*/
vdev_raidz_matrix_invert(rr, n, nmissing_rows, missing_rows, rows,
invrows, used);
/*
* Reconstruct the missing data using the generated matrix.
*/
vdev_raidz_matrix_reconstruct(rr, n, nmissing_rows, missing_rows,
invrows, used);
kmem_free(p, psize);
/*
* copy back from temporary linear abds and free them
*/
if (bufs) {
for (c = rr->rr_firstdatacol; c < rr->rr_cols; c++) {
raidz_col_t *col = &rr->rr_col[c];
if (bufs[c] != NULL) {
abd_copy(bufs[c], col->rc_abd, col->rc_size);
abd_free(col->rc_abd);
}
col->rc_abd = bufs[c];
}
kmem_free(bufs, rr->rr_cols * sizeof (abd_t *));
}
}
static void
vdev_raidz_reconstruct_row(raidz_map_t *rm, raidz_row_t *rr,
const int *t, int nt)
{
int tgts[VDEV_RAIDZ_MAXPARITY], *dt;
int ntgts;
int i, c, ret;
int nbadparity, nbaddata;
int parity_valid[VDEV_RAIDZ_MAXPARITY];
nbadparity = rr->rr_firstdatacol;
nbaddata = rr->rr_cols - nbadparity;
ntgts = 0;
for (i = 0, c = 0; c < rr->rr_cols; c++) {
if (c < rr->rr_firstdatacol)
parity_valid[c] = B_FALSE;
if (i < nt && c == t[i]) {
tgts[ntgts++] = c;
i++;
} else if (rr->rr_col[c].rc_error != 0) {
tgts[ntgts++] = c;
} else if (c >= rr->rr_firstdatacol) {
nbaddata--;
} else {
parity_valid[c] = B_TRUE;
nbadparity--;
}
}
ASSERT(ntgts >= nt);
ASSERT(nbaddata >= 0);
ASSERT(nbaddata + nbadparity == ntgts);
dt = &tgts[nbadparity];
/* Reconstruct using the new math implementation */
ret = vdev_raidz_math_reconstruct(rm, rr, parity_valid, dt, nbaddata);
if (ret != RAIDZ_ORIGINAL_IMPL)
return;
/*
* See if we can use any of our optimized reconstruction routines.
*/
switch (nbaddata) {
case 1:
if (parity_valid[VDEV_RAIDZ_P]) {
vdev_raidz_reconstruct_p(rr, dt, 1);
return;
}
ASSERT(rr->rr_firstdatacol > 1);
if (parity_valid[VDEV_RAIDZ_Q]) {
vdev_raidz_reconstruct_q(rr, dt, 1);
return;
}
ASSERT(rr->rr_firstdatacol > 2);
break;
case 2:
ASSERT(rr->rr_firstdatacol > 1);
if (parity_valid[VDEV_RAIDZ_P] &&
parity_valid[VDEV_RAIDZ_Q]) {
vdev_raidz_reconstruct_pq(rr, dt, 2);
return;
}
ASSERT(rr->rr_firstdatacol > 2);
break;
}
vdev_raidz_reconstruct_general(rr, tgts, ntgts);
}
static int
vdev_raidz_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
uint64_t *logical_ashift, uint64_t *physical_ashift)
{
vdev_raidz_t *vdrz = vd->vdev_tsd;
uint64_t nparity = vdrz->vd_nparity;
int c;
int lasterror = 0;
int numerrors = 0;
ASSERT(nparity > 0);
if (nparity > VDEV_RAIDZ_MAXPARITY ||
vd->vdev_children < nparity + 1) {
vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
return (SET_ERROR(EINVAL));
}
vdev_open_children(vd);
for (c = 0; c < vd->vdev_children; c++) {
vdev_t *cvd = vd->vdev_child[c];
if (cvd->vdev_open_error != 0) {
lasterror = cvd->vdev_open_error;
numerrors++;
continue;
}
*asize = MIN(*asize - 1, cvd->vdev_asize - 1) + 1;
*max_asize = MIN(*max_asize - 1, cvd->vdev_max_asize - 1) + 1;
*logical_ashift = MAX(*logical_ashift, cvd->vdev_ashift);
}
for (c = 0; c < vd->vdev_children; c++) {
vdev_t *cvd = vd->vdev_child[c];
if (cvd->vdev_open_error != 0)
continue;
*physical_ashift = vdev_best_ashift(*logical_ashift,
*physical_ashift, cvd->vdev_physical_ashift);
}
*asize *= vd->vdev_children;
*max_asize *= vd->vdev_children;
if (numerrors > nparity) {
vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
return (lasterror);
}
return (0);
}
static void
vdev_raidz_close(vdev_t *vd)
{
for (int c = 0; c < vd->vdev_children; c++) {
if (vd->vdev_child[c] != NULL)
vdev_close(vd->vdev_child[c]);
}
}
static uint64_t
vdev_raidz_asize(vdev_t *vd, uint64_t psize)
{
vdev_raidz_t *vdrz = vd->vdev_tsd;
uint64_t asize;
uint64_t ashift = vd->vdev_top->vdev_ashift;
uint64_t cols = vdrz->vd_logical_width;
uint64_t nparity = vdrz->vd_nparity;
asize = ((psize - 1) >> ashift) + 1;
asize += nparity * ((asize + cols - nparity - 1) / (cols - nparity));
asize = roundup(asize, nparity + 1) << ashift;
return (asize);
}
/*
* The allocatable space for a raidz vdev is N * sizeof(smallest child)
* so each child must provide at least 1/Nth of its asize.
*/
static uint64_t
vdev_raidz_min_asize(vdev_t *vd)
{
return ((vd->vdev_min_asize + vd->vdev_children - 1) /
vd->vdev_children);
}
void
vdev_raidz_child_done(zio_t *zio)
{
raidz_col_t *rc = zio->io_private;
ASSERT3P(rc->rc_abd, !=, NULL);
rc->rc_error = zio->io_error;
rc->rc_tried = 1;
rc->rc_skipped = 0;
}
static void
vdev_raidz_io_verify(vdev_t *vd, raidz_row_t *rr, int col)
{
#ifdef ZFS_DEBUG
vdev_t *tvd = vd->vdev_top;
range_seg64_t logical_rs, physical_rs, remain_rs;
logical_rs.rs_start = rr->rr_offset;
logical_rs.rs_end = logical_rs.rs_start +
vdev_raidz_asize(vd, rr->rr_size);
raidz_col_t *rc = &rr->rr_col[col];
vdev_t *cvd = vd->vdev_child[rc->rc_devidx];
vdev_xlate(cvd, &logical_rs, &physical_rs, &remain_rs);
ASSERT(vdev_xlate_is_empty(&remain_rs));
ASSERT3U(rc->rc_offset, ==, physical_rs.rs_start);
ASSERT3U(rc->rc_offset, <, physical_rs.rs_end);
/*
* It would be nice to assert that rs_end is equal
* to rc_offset + rc_size but there might be an
* optional I/O at the end that is not accounted in
* rc_size.
*/
if (physical_rs.rs_end > rc->rc_offset + rc->rc_size) {
ASSERT3U(physical_rs.rs_end, ==, rc->rc_offset +
rc->rc_size + (1 << tvd->vdev_ashift));
} else {
ASSERT3U(physical_rs.rs_end, ==, rc->rc_offset + rc->rc_size);
}
#endif
}
static void
vdev_raidz_io_start_write(zio_t *zio, raidz_row_t *rr, uint64_t ashift)
{
vdev_t *vd = zio->io_vd;
raidz_map_t *rm = zio->io_vsd;
vdev_raidz_generate_parity_row(rm, rr);
for (int c = 0; c < rr->rr_scols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
vdev_t *cvd = vd->vdev_child[rc->rc_devidx];
/* Verify physical to logical translation */
vdev_raidz_io_verify(vd, rr, c);
if (rc->rc_size > 0) {
ASSERT3P(rc->rc_abd, !=, NULL);
zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
rc->rc_offset, rc->rc_abd,
abd_get_size(rc->rc_abd), zio->io_type,
zio->io_priority, 0, vdev_raidz_child_done, rc));
} else {
/*
* Generate optional write for skip sector to improve
* aggregation contiguity.
*/
ASSERT3P(rc->rc_abd, ==, NULL);
zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
rc->rc_offset, NULL, 1ULL << ashift,
zio->io_type, zio->io_priority,
ZIO_FLAG_NODATA | ZIO_FLAG_OPTIONAL, NULL,
NULL));
}
}
}
static void
vdev_raidz_io_start_read(zio_t *zio, raidz_row_t *rr)
{
vdev_t *vd = zio->io_vd;
/*
* Iterate over the columns in reverse order so that we hit the parity
* last -- any errors along the way will force us to read the parity.
*/
for (int c = rr->rr_cols - 1; c >= 0; c--) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_size == 0)
continue;
vdev_t *cvd = vd->vdev_child[rc->rc_devidx];
if (!vdev_readable(cvd)) {
if (c >= rr->rr_firstdatacol)
rr->rr_missingdata++;
else
rr->rr_missingparity++;
rc->rc_error = SET_ERROR(ENXIO);
rc->rc_tried = 1; /* don't even try */
rc->rc_skipped = 1;
continue;
}
if (vdev_dtl_contains(cvd, DTL_MISSING, zio->io_txg, 1)) {
if (c >= rr->rr_firstdatacol)
rr->rr_missingdata++;
else
rr->rr_missingparity++;
rc->rc_error = SET_ERROR(ESTALE);
rc->rc_skipped = 1;
continue;
}
if (c >= rr->rr_firstdatacol || rr->rr_missingdata > 0 ||
(zio->io_flags & (ZIO_FLAG_SCRUB | ZIO_FLAG_RESILVER))) {
zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
rc->rc_offset, rc->rc_abd, rc->rc_size,
zio->io_type, zio->io_priority, 0,
vdev_raidz_child_done, rc));
}
}
}
/*
* Start an IO operation on a RAIDZ VDev
*
* Outline:
* - For write operations:
* 1. Generate the parity data
* 2. Create child zio write operations to each column's vdev, for both
* data and parity.
* 3. If the column skips any sectors for padding, create optional dummy
* write zio children for those areas to improve aggregation continuity.
* - For read operations:
* 1. Create child zio read operations to each data column's vdev to read
* the range of data required for zio.
* 2. If this is a scrub or resilver operation, or if any of the data
* vdevs have had errors, then create zio read operations to the parity
* columns' VDevs as well.
*/
static void
vdev_raidz_io_start(zio_t *zio)
{
vdev_t *vd = zio->io_vd;
vdev_t *tvd = vd->vdev_top;
vdev_raidz_t *vdrz = vd->vdev_tsd;
raidz_map_t *rm = vdev_raidz_map_alloc(zio, tvd->vdev_ashift,
vdrz->vd_logical_width, vdrz->vd_nparity);
zio->io_vsd = rm;
zio->io_vsd_ops = &vdev_raidz_vsd_ops;
/*
* Until raidz expansion is implemented all maps for a raidz vdev
* contain a single row.
*/
ASSERT3U(rm->rm_nrows, ==, 1);
raidz_row_t *rr = rm->rm_row[0];
if (zio->io_type == ZIO_TYPE_WRITE) {
vdev_raidz_io_start_write(zio, rr, tvd->vdev_ashift);
} else {
ASSERT(zio->io_type == ZIO_TYPE_READ);
vdev_raidz_io_start_read(zio, rr);
}
zio_execute(zio);
}
/*
* Report a checksum error for a child of a RAID-Z device.
*/
void
vdev_raidz_checksum_error(zio_t *zio, raidz_col_t *rc, abd_t *bad_data)
{
vdev_t *vd = zio->io_vd->vdev_child[rc->rc_devidx];
if (!(zio->io_flags & ZIO_FLAG_SPECULATIVE) &&
zio->io_priority != ZIO_PRIORITY_REBUILD) {
zio_bad_cksum_t zbc;
raidz_map_t *rm = zio->io_vsd;
zbc.zbc_has_cksum = 0;
zbc.zbc_injected = rm->rm_ecksuminjected;
(void) zfs_ereport_post_checksum(zio->io_spa, vd,
&zio->io_bookmark, zio, rc->rc_offset, rc->rc_size,
rc->rc_abd, bad_data, &zbc);
mutex_enter(&vd->vdev_stat_lock);
vd->vdev_stat.vs_checksum_errors++;
mutex_exit(&vd->vdev_stat_lock);
}
}
/*
* We keep track of whether or not there were any injected errors, so that
* any ereports we generate can note it.
*/
static int
raidz_checksum_verify(zio_t *zio)
{
zio_bad_cksum_t zbc = {{{0}}};
raidz_map_t *rm = zio->io_vsd;
int ret = zio_checksum_error(zio, &zbc);
if (ret != 0 && zbc.zbc_injected != 0)
rm->rm_ecksuminjected = 1;
return (ret);
}
/*
* Generate the parity from the data columns. If we tried and were able to
* read the parity without error, verify that the generated parity matches the
* data we read. If it doesn't, we fire off a checksum error. Return the
* number of such failures.
*/
static int
raidz_parity_verify(zio_t *zio, raidz_row_t *rr)
{
abd_t *orig[VDEV_RAIDZ_MAXPARITY];
int c, ret = 0;
raidz_map_t *rm = zio->io_vsd;
raidz_col_t *rc;
blkptr_t *bp = zio->io_bp;
enum zio_checksum checksum = (bp == NULL ? zio->io_prop.zp_checksum :
(BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER : BP_GET_CHECKSUM(bp)));
if (checksum == ZIO_CHECKSUM_NOPARITY)
return (ret);
for (c = 0; c < rr->rr_firstdatacol; c++) {
rc = &rr->rr_col[c];
if (!rc->rc_tried || rc->rc_error != 0)
continue;
orig[c] = rc->rc_abd;
ASSERT3U(abd_get_size(rc->rc_abd), ==, rc->rc_size);
rc->rc_abd = abd_alloc_linear(rc->rc_size, B_FALSE);
}
/*
* Verify any empty sectors are zero filled to ensure the parity
* is calculated correctly even if these non-data sectors are damaged.
*/
if (rr->rr_nempty && rr->rr_abd_empty != NULL)
ret += vdev_draid_map_verify_empty(zio, rr);
/*
* Regenerates parity even for !tried||rc_error!=0 columns. This
* isn't harmful but it does have the side effect of fixing stuff
* we didn't realize was necessary (i.e. even if we return 0).
*/
vdev_raidz_generate_parity_row(rm, rr);
for (c = 0; c < rr->rr_firstdatacol; c++) {
rc = &rr->rr_col[c];
if (!rc->rc_tried || rc->rc_error != 0)
continue;
if (abd_cmp(orig[c], rc->rc_abd) != 0) {
vdev_raidz_checksum_error(zio, rc, orig[c]);
rc->rc_error = SET_ERROR(ECKSUM);
ret++;
}
abd_free(orig[c]);
}
return (ret);
}
static int
vdev_raidz_worst_error(raidz_row_t *rr)
{
int error = 0;
for (int c = 0; c < rr->rr_cols; c++)
error = zio_worst_error(error, rr->rr_col[c].rc_error);
return (error);
}
static void
vdev_raidz_io_done_verified(zio_t *zio, raidz_row_t *rr)
{
int unexpected_errors = 0;
int parity_errors = 0;
int parity_untried = 0;
int data_errors = 0;
ASSERT3U(zio->io_type, ==, ZIO_TYPE_READ);
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_error) {
if (c < rr->rr_firstdatacol)
parity_errors++;
else
data_errors++;
if (!rc->rc_skipped)
unexpected_errors++;
} else if (c < rr->rr_firstdatacol && !rc->rc_tried) {
parity_untried++;
}
if (rc->rc_force_repair)
unexpected_errors++;
}
/*
* If we read more parity disks than were used for
* reconstruction, confirm that the other parity disks produced
* correct data.
*
* Note that we also regenerate parity when resilvering so we
* can write it out to failed devices later.
*/
if (parity_errors + parity_untried <
rr->rr_firstdatacol - data_errors ||
(zio->io_flags & ZIO_FLAG_RESILVER)) {
int n = raidz_parity_verify(zio, rr);
unexpected_errors += n;
}
if (zio->io_error == 0 && spa_writeable(zio->io_spa) &&
(unexpected_errors > 0 || (zio->io_flags & ZIO_FLAG_RESILVER))) {
/*
* Use the good data we have in hand to repair damaged children.
*/
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
vdev_t *vd = zio->io_vd;
vdev_t *cvd = vd->vdev_child[rc->rc_devidx];
if (!rc->rc_allow_repair) {
continue;
} else if (!rc->rc_force_repair &&
(rc->rc_error == 0 || rc->rc_size == 0)) {
continue;
}
zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
rc->rc_offset, rc->rc_abd, rc->rc_size,
ZIO_TYPE_WRITE,
zio->io_priority == ZIO_PRIORITY_REBUILD ?
ZIO_PRIORITY_REBUILD : ZIO_PRIORITY_ASYNC_WRITE,
ZIO_FLAG_IO_REPAIR | (unexpected_errors ?
ZIO_FLAG_SELF_HEAL : 0), NULL, NULL));
}
}
}
static void
raidz_restore_orig_data(raidz_map_t *rm)
{
for (int i = 0; i < rm->rm_nrows; i++) {
raidz_row_t *rr = rm->rm_row[i];
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_need_orig_restore) {
abd_copy(rc->rc_abd,
rc->rc_orig_data, rc->rc_size);
rc->rc_need_orig_restore = B_FALSE;
}
}
}
}
/*
* returns EINVAL if reconstruction of the block will not be possible
* returns ECKSUM if this specific reconstruction failed
* returns 0 on successful reconstruction
*/
static int
raidz_reconstruct(zio_t *zio, int *ltgts, int ntgts, int nparity)
{
raidz_map_t *rm = zio->io_vsd;
/* Reconstruct each row */
for (int r = 0; r < rm->rm_nrows; r++) {
raidz_row_t *rr = rm->rm_row[r];
int my_tgts[VDEV_RAIDZ_MAXPARITY]; /* value is child id */
int t = 0;
int dead = 0;
int dead_data = 0;
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
ASSERT0(rc->rc_need_orig_restore);
if (rc->rc_error != 0) {
dead++;
if (c >= nparity)
dead_data++;
continue;
}
if (rc->rc_size == 0)
continue;
for (int lt = 0; lt < ntgts; lt++) {
if (rc->rc_devidx == ltgts[lt]) {
if (rc->rc_orig_data == NULL) {
rc->rc_orig_data =
abd_alloc_linear(
rc->rc_size, B_TRUE);
abd_copy(rc->rc_orig_data,
rc->rc_abd, rc->rc_size);
}
rc->rc_need_orig_restore = B_TRUE;
dead++;
if (c >= nparity)
dead_data++;
my_tgts[t++] = c;
break;
}
}
}
if (dead > nparity) {
/* reconstruction not possible */
raidz_restore_orig_data(rm);
return (EINVAL);
}
if (dead_data > 0)
vdev_raidz_reconstruct_row(rm, rr, my_tgts, t);
}
/* Check for success */
if (raidz_checksum_verify(zio) == 0) {
/* Reconstruction succeeded - report errors */
for (int i = 0; i < rm->rm_nrows; i++) {
raidz_row_t *rr = rm->rm_row[i];
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_need_orig_restore) {
/*
* Note: if this is a parity column,
* we don't really know if it's wrong.
* We need to let
* vdev_raidz_io_done_verified() check
* it, and if we set rc_error, it will
* think that it is a "known" error
* that doesn't need to be checked
* or corrected.
*/
if (rc->rc_error == 0 &&
c >= rr->rr_firstdatacol) {
vdev_raidz_checksum_error(zio,
rc, rc->rc_orig_data);
rc->rc_error =
SET_ERROR(ECKSUM);
}
rc->rc_need_orig_restore = B_FALSE;
}
}
vdev_raidz_io_done_verified(zio, rr);
}
zio_checksum_verified(zio);
return (0);
}
/* Reconstruction failed - restore original data */
raidz_restore_orig_data(rm);
return (ECKSUM);
}
/*
* Iterate over all combinations of N bad vdevs and attempt a reconstruction.
* Note that the algorithm below is non-optimal because it doesn't take into
* account how reconstruction is actually performed. For example, with
* triple-parity RAID-Z the reconstruction procedure is the same if column 4
* is targeted as invalid as if columns 1 and 4 are targeted since in both
* cases we'd only use parity information in column 0.
*
* The order that we find the various possible combinations of failed
* disks is dictated by these rules:
* - Examine each "slot" (the "i" in tgts[i])
* - Try to increment this slot (tgts[i] = tgts[i] + 1)
* - if we can't increment because it runs into the next slot,
* reset our slot to the minimum, and examine the next slot
*
* For example, with a 6-wide RAIDZ3, and no known errors (so we have to choose
* 3 columns to reconstruct), we will generate the following sequence:
*
* STATE ACTION
* 0 1 2 special case: skip since these are all parity
* 0 1 3 first slot: reset to 0; middle slot: increment to 2
* 0 2 3 first slot: increment to 1
* 1 2 3 first: reset to 0; middle: reset to 1; last: increment to 4
* 0 1 4 first: reset to 0; middle: increment to 2
* 0 2 4 first: increment to 1
* 1 2 4 first: reset to 0; middle: increment to 3
* 0 3 4 first: increment to 1
* 1 3 4 first: increment to 2
* 2 3 4 first: reset to 0; middle: reset to 1; last: increment to 5
* 0 1 5 first: reset to 0; middle: increment to 2
* 0 2 5 first: increment to 1
* 1 2 5 first: reset to 0; middle: increment to 3
* 0 3 5 first: increment to 1
* 1 3 5 first: increment to 2
* 2 3 5 first: reset to 0; middle: increment to 4
* 0 4 5 first: increment to 1
* 1 4 5 first: increment to 2
* 2 4 5 first: increment to 3
* 3 4 5 done
*
* This strategy works for dRAID but is less efficient when there are a large
* number of child vdevs and therefore permutations to check. Furthermore,
* since the raidz_map_t rows likely do not overlap reconstruction would be
* possible as long as there are no more than nparity data errors per row.
* These additional permutations are not currently checked but could be as
* a future improvement.
*/
static int
vdev_raidz_combrec(zio_t *zio)
{
int nparity = vdev_get_nparity(zio->io_vd);
raidz_map_t *rm = zio->io_vsd;
/* Check if there's enough data to attempt reconstrution. */
for (int i = 0; i < rm->rm_nrows; i++) {
raidz_row_t *rr = rm->rm_row[i];
int total_errors = 0;
for (int c = 0; c < rr->rr_cols; c++) {
if (rr->rr_col[c].rc_error)
total_errors++;
}
if (total_errors > nparity)
return (vdev_raidz_worst_error(rr));
}
for (int num_failures = 1; num_failures <= nparity; num_failures++) {
int tstore[VDEV_RAIDZ_MAXPARITY + 2];
int *ltgts = &tstore[1]; /* value is logical child ID */
/* Determine number of logical children, n */
int n = zio->io_vd->vdev_children;
ASSERT3U(num_failures, <=, nparity);
ASSERT3U(num_failures, <=, VDEV_RAIDZ_MAXPARITY);
/* Handle corner cases in combrec logic */
ltgts[-1] = -1;
for (int i = 0; i < num_failures; i++) {
ltgts[i] = i;
}
ltgts[num_failures] = n;
for (;;) {
int err = raidz_reconstruct(zio, ltgts, num_failures,
nparity);
if (err == EINVAL) {
/*
* Reconstruction not possible with this #
* failures; try more failures.
*/
break;
} else if (err == 0)
return (0);
/* Compute next targets to try */
for (int t = 0; ; t++) {
ASSERT3U(t, <, num_failures);
ltgts[t]++;
if (ltgts[t] == n) {
/* try more failures */
ASSERT3U(t, ==, num_failures - 1);
break;
}
ASSERT3U(ltgts[t], <, n);
ASSERT3U(ltgts[t], <=, ltgts[t + 1]);
/*
* If that spot is available, we're done here.
* Try the next combination.
*/
if (ltgts[t] != ltgts[t + 1])
break;
/*
* Otherwise, reset this tgt to the minimum,
* and move on to the next tgt.
*/
ltgts[t] = ltgts[t - 1] + 1;
ASSERT3U(ltgts[t], ==, t);
}
/* Increase the number of failures and keep trying. */
if (ltgts[num_failures - 1] == n)
break;
}
}
return (ECKSUM);
}
void
vdev_raidz_reconstruct(raidz_map_t *rm, const int *t, int nt)
{
for (uint64_t row = 0; row < rm->rm_nrows; row++) {
raidz_row_t *rr = rm->rm_row[row];
vdev_raidz_reconstruct_row(rm, rr, t, nt);
}
}
/*
* Complete a write IO operation on a RAIDZ VDev
*
* Outline:
* 1. Check for errors on the child IOs.
* 2. Return, setting an error code if too few child VDevs were written
* to reconstruct the data later. Note that partial writes are
* considered successful if they can be reconstructed at all.
*/
static void
vdev_raidz_io_done_write_impl(zio_t *zio, raidz_row_t *rr)
{
int total_errors = 0;
ASSERT3U(rr->rr_missingparity, <=, rr->rr_firstdatacol);
ASSERT3U(rr->rr_missingdata, <=, rr->rr_cols - rr->rr_firstdatacol);
ASSERT3U(zio->io_type, ==, ZIO_TYPE_WRITE);
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_error) {
ASSERT(rc->rc_error != ECKSUM); /* child has no bp */
total_errors++;
}
}
/*
* Treat partial writes as a success. If we couldn't write enough
* columns to reconstruct the data, the I/O failed. Otherwise,
* good enough.
*
* Now that we support write reallocation, it would be better
* to treat partial failure as real failure unless there are
* no non-degraded top-level vdevs left, and not update DTLs
* if we intend to reallocate.
*/
if (total_errors > rr->rr_firstdatacol) {
zio->io_error = zio_worst_error(zio->io_error,
vdev_raidz_worst_error(rr));
}
}
static void
vdev_raidz_io_done_reconstruct_known_missing(zio_t *zio, raidz_map_t *rm,
raidz_row_t *rr)
{
int parity_errors = 0;
int parity_untried = 0;
int data_errors = 0;
int total_errors = 0;
ASSERT3U(rr->rr_missingparity, <=, rr->rr_firstdatacol);
ASSERT3U(rr->rr_missingdata, <=, rr->rr_cols - rr->rr_firstdatacol);
ASSERT3U(zio->io_type, ==, ZIO_TYPE_READ);
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
/*
* If scrubbing and a replacing/sparing child vdev determined
* that not all of its children have an identical copy of the
* data, then clear the error so the column is treated like
* any other read and force a repair to correct the damage.
*/
if (rc->rc_error == ECKSUM) {
ASSERT(zio->io_flags & ZIO_FLAG_SCRUB);
vdev_raidz_checksum_error(zio, rc, rc->rc_abd);
rc->rc_force_repair = 1;
rc->rc_error = 0;
}
if (rc->rc_error) {
if (c < rr->rr_firstdatacol)
parity_errors++;
else
data_errors++;
total_errors++;
} else if (c < rr->rr_firstdatacol && !rc->rc_tried) {
parity_untried++;
}
}
/*
* If there were data errors and the number of errors we saw was
* correctable -- less than or equal to the number of parity disks read
* -- reconstruct based on the missing data.
*/
if (data_errors != 0 &&
total_errors <= rr->rr_firstdatacol - parity_untried) {
/*
* We either attempt to read all the parity columns or
* none of them. If we didn't try to read parity, we
* wouldn't be here in the correctable case. There must
* also have been fewer parity errors than parity
* columns or, again, we wouldn't be in this code path.
*/
ASSERT(parity_untried == 0);
ASSERT(parity_errors < rr->rr_firstdatacol);
/*
* Identify the data columns that reported an error.
*/
int n = 0;
int tgts[VDEV_RAIDZ_MAXPARITY];
for (int c = rr->rr_firstdatacol; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_error != 0) {
ASSERT(n < VDEV_RAIDZ_MAXPARITY);
tgts[n++] = c;
}
}
ASSERT(rr->rr_firstdatacol >= n);
vdev_raidz_reconstruct_row(rm, rr, tgts, n);
}
}
/*
* Return the number of reads issued.
*/
static int
vdev_raidz_read_all(zio_t *zio, raidz_row_t *rr)
{
vdev_t *vd = zio->io_vd;
int nread = 0;
rr->rr_missingdata = 0;
rr->rr_missingparity = 0;
/*
* If this rows contains empty sectors which are not required
* for a normal read then allocate an ABD for them now so they
* may be read, verified, and any needed repairs performed.
*/
if (rr->rr_nempty && rr->rr_abd_empty == NULL)
vdev_draid_map_alloc_empty(zio, rr);
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
if (rc->rc_tried || rc->rc_size == 0)
continue;
zio_nowait(zio_vdev_child_io(zio, NULL,
vd->vdev_child[rc->rc_devidx],
rc->rc_offset, rc->rc_abd, rc->rc_size,
zio->io_type, zio->io_priority, 0,
vdev_raidz_child_done, rc));
nread++;
}
return (nread);
}
/*
* We're here because either there were too many errors to even attempt
* reconstruction (total_errors == rm_first_datacol), or vdev_*_combrec()
* failed. In either case, there is enough bad data to prevent reconstruction.
* Start checksum ereports for all children which haven't failed.
*/
static void
vdev_raidz_io_done_unrecoverable(zio_t *zio)
{
raidz_map_t *rm = zio->io_vsd;
for (int i = 0; i < rm->rm_nrows; i++) {
raidz_row_t *rr = rm->rm_row[i];
for (int c = 0; c < rr->rr_cols; c++) {
raidz_col_t *rc = &rr->rr_col[c];
vdev_t *cvd = zio->io_vd->vdev_child[rc->rc_devidx];
if (rc->rc_error != 0)
continue;
zio_bad_cksum_t zbc;
zbc.zbc_has_cksum = 0;
zbc.zbc_injected = rm->rm_ecksuminjected;
(void) zfs_ereport_start_checksum(zio->io_spa,
cvd, &zio->io_bookmark, zio, rc->rc_offset,
rc->rc_size, &zbc);
mutex_enter(&cvd->vdev_stat_lock);
cvd->vdev_stat.vs_checksum_errors++;
mutex_exit(&cvd->vdev_stat_lock);
}
}
}
void
vdev_raidz_io_done(zio_t *zio)
{
raidz_map_t *rm = zio->io_vsd;
if (zio->io_type == ZIO_TYPE_WRITE) {
for (int i = 0; i < rm->rm_nrows; i++) {
vdev_raidz_io_done_write_impl(zio, rm->rm_row[i]);
}
} else {
for (int i = 0; i < rm->rm_nrows; i++) {
raidz_row_t *rr = rm->rm_row[i];
vdev_raidz_io_done_reconstruct_known_missing(zio,
rm, rr);
}
if (raidz_checksum_verify(zio) == 0) {
for (int i = 0; i < rm->rm_nrows; i++) {
raidz_row_t *rr = rm->rm_row[i];
vdev_raidz_io_done_verified(zio, rr);
}
zio_checksum_verified(zio);
} else {
/*
* A sequential resilver has no checksum which makes
* combinatoral reconstruction impossible. This code
* path is unreachable since raidz_checksum_verify()
* has no checksum to verify and must succeed.
*/
ASSERT3U(zio->io_priority, !=, ZIO_PRIORITY_REBUILD);
/*
* This isn't a typical situation -- either we got a
* read error or a child silently returned bad data.
* Read every block so we can try again with as much
* data and parity as we can track down. If we've
* already been through once before, all children will
* be marked as tried so we'll proceed to combinatorial
* reconstruction.
*/
int nread = 0;
for (int i = 0; i < rm->rm_nrows; i++) {
nread += vdev_raidz_read_all(zio,
rm->rm_row[i]);
}
if (nread != 0) {
/*
* Normally our stage is VDEV_IO_DONE, but if
* we've already called redone(), it will have
* changed to VDEV_IO_START, in which case we
* don't want to call redone() again.
*/
if (zio->io_stage != ZIO_STAGE_VDEV_IO_START)
zio_vdev_io_redone(zio);
return;
}
zio->io_error = vdev_raidz_combrec(zio);
if (zio->io_error == ECKSUM &&
!(zio->io_flags & ZIO_FLAG_SPECULATIVE)) {
vdev_raidz_io_done_unrecoverable(zio);
}
}
}
}
static void
vdev_raidz_state_change(vdev_t *vd, int faulted, int degraded)
{
vdev_raidz_t *vdrz = vd->vdev_tsd;
if (faulted > vdrz->vd_nparity)
vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
VDEV_AUX_NO_REPLICAS);
else if (degraded + faulted != 0)
vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
else
vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
}
/*
* Determine if any portion of the provided block resides on a child vdev
* with a dirty DTL and therefore needs to be resilvered. The function
* assumes that at least one DTL is dirty which implies that full stripe
* width blocks must be resilvered.
*/
static boolean_t
vdev_raidz_need_resilver(vdev_t *vd, const dva_t *dva, size_t psize,
uint64_t phys_birth)
{
vdev_raidz_t *vdrz = vd->vdev_tsd;
uint64_t dcols = vd->vdev_children;
uint64_t nparity = vdrz->vd_nparity;
uint64_t ashift = vd->vdev_top->vdev_ashift;
/* The starting RAIDZ (parent) vdev sector of the block. */
uint64_t b = DVA_GET_OFFSET(dva) >> ashift;
/* The zio's size in units of the vdev's minimum sector size. */
uint64_t s = ((psize - 1) >> ashift) + 1;
/* The first column for this stripe. */
uint64_t f = b % dcols;
/* Unreachable by sequential resilver. */
ASSERT3U(phys_birth, !=, TXG_UNKNOWN);
if (!vdev_dtl_contains(vd, DTL_PARTIAL, phys_birth, 1))
return (B_FALSE);
if (s + nparity >= dcols)
return (B_TRUE);
for (uint64_t c = 0; c < s + nparity; c++) {
uint64_t devidx = (f + c) % dcols;
vdev_t *cvd = vd->vdev_child[devidx];
/*
* dsl_scan_need_resilver() already checked vd with
* vdev_dtl_contains(). So here just check cvd with
* vdev_dtl_empty(), cheaper and a good approximation.
*/
if (!vdev_dtl_empty(cvd, DTL_PARTIAL))
return (B_TRUE);
}
return (B_FALSE);
}
static void
vdev_raidz_xlate(vdev_t *cvd, const range_seg64_t *logical_rs,
range_seg64_t *physical_rs, range_seg64_t *remain_rs)
{
(void) remain_rs;
vdev_t *raidvd = cvd->vdev_parent;
ASSERT(raidvd->vdev_ops == &vdev_raidz_ops);
uint64_t width = raidvd->vdev_children;
uint64_t tgt_col = cvd->vdev_id;
uint64_t ashift = raidvd->vdev_top->vdev_ashift;
/* make sure the offsets are block-aligned */
ASSERT0(logical_rs->rs_start % (1 << ashift));
ASSERT0(logical_rs->rs_end % (1 << ashift));
uint64_t b_start = logical_rs->rs_start >> ashift;
uint64_t b_end = logical_rs->rs_end >> ashift;
uint64_t start_row = 0;
if (b_start > tgt_col) /* avoid underflow */
start_row = ((b_start - tgt_col - 1) / width) + 1;
uint64_t end_row = 0;
if (b_end > tgt_col)
end_row = ((b_end - tgt_col - 1) / width) + 1;
physical_rs->rs_start = start_row << ashift;
physical_rs->rs_end = end_row << ashift;
ASSERT3U(physical_rs->rs_start, <=, logical_rs->rs_start);
ASSERT3U(physical_rs->rs_end - physical_rs->rs_start, <=,
logical_rs->rs_end - logical_rs->rs_start);
}
/*
* Initialize private RAIDZ specific fields from the nvlist.
*/
static int
vdev_raidz_init(spa_t *spa, nvlist_t *nv, void **tsd)
{
vdev_raidz_t *vdrz;
uint64_t nparity;
uint_t children;
nvlist_t **child;
int error = nvlist_lookup_nvlist_array(nv,
ZPOOL_CONFIG_CHILDREN, &child, &children);
if (error != 0)
return (SET_ERROR(EINVAL));
if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_NPARITY, &nparity) == 0) {
if (nparity == 0 || nparity > VDEV_RAIDZ_MAXPARITY)
return (SET_ERROR(EINVAL));
/*
* Previous versions could only support 1 or 2 parity
* device.
*/
if (nparity > 1 && spa_version(spa) < SPA_VERSION_RAIDZ2)
return (SET_ERROR(EINVAL));
else if (nparity > 2 && spa_version(spa) < SPA_VERSION_RAIDZ3)
return (SET_ERROR(EINVAL));
} else {
/*
* We require the parity to be specified for SPAs that
* support multiple parity levels.
*/
if (spa_version(spa) >= SPA_VERSION_RAIDZ2)
return (SET_ERROR(EINVAL));
/*
* Otherwise, we default to 1 parity device for RAID-Z.
*/
nparity = 1;
}
vdrz = kmem_zalloc(sizeof (*vdrz), KM_SLEEP);
vdrz->vd_logical_width = children;
vdrz->vd_nparity = nparity;
*tsd = vdrz;
return (0);
}
static void
vdev_raidz_fini(vdev_t *vd)
{
kmem_free(vd->vdev_tsd, sizeof (vdev_raidz_t));
}
/*
* Add RAIDZ specific fields to the config nvlist.
*/
static void
vdev_raidz_config_generate(vdev_t *vd, nvlist_t *nv)
{
ASSERT3P(vd->vdev_ops, ==, &vdev_raidz_ops);
vdev_raidz_t *vdrz = vd->vdev_tsd;
/*
* Make sure someone hasn't managed to sneak a fancy new vdev
* into a crufty old storage pool.
*/
ASSERT(vdrz->vd_nparity == 1 ||
(vdrz->vd_nparity <= 2 &&
spa_version(vd->vdev_spa) >= SPA_VERSION_RAIDZ2) ||
(vdrz->vd_nparity <= 3 &&
spa_version(vd->vdev_spa) >= SPA_VERSION_RAIDZ3));
/*
* Note that we'll add these even on storage pools where they
* aren't strictly required -- older software will just ignore
* it.
*/
fnvlist_add_uint64(nv, ZPOOL_CONFIG_NPARITY, vdrz->vd_nparity);
}
static uint64_t
vdev_raidz_nparity(vdev_t *vd)
{
vdev_raidz_t *vdrz = vd->vdev_tsd;
return (vdrz->vd_nparity);
}
static uint64_t
vdev_raidz_ndisks(vdev_t *vd)
{
return (vd->vdev_children);
}
vdev_ops_t vdev_raidz_ops = {
.vdev_op_init = vdev_raidz_init,
.vdev_op_fini = vdev_raidz_fini,
.vdev_op_open = vdev_raidz_open,
.vdev_op_close = vdev_raidz_close,
.vdev_op_asize = vdev_raidz_asize,
.vdev_op_min_asize = vdev_raidz_min_asize,
.vdev_op_min_alloc = NULL,
.vdev_op_io_start = vdev_raidz_io_start,
.vdev_op_io_done = vdev_raidz_io_done,
.vdev_op_state_change = vdev_raidz_state_change,
.vdev_op_need_resilver = vdev_raidz_need_resilver,
.vdev_op_hold = NULL,
.vdev_op_rele = NULL,
.vdev_op_remap = NULL,
.vdev_op_xlate = vdev_raidz_xlate,
.vdev_op_rebuild_asize = NULL,
.vdev_op_metaslab_init = NULL,
.vdev_op_config_generate = vdev_raidz_config_generate,
.vdev_op_nparity = vdev_raidz_nparity,
.vdev_op_ndisks = vdev_raidz_ndisks,
.vdev_op_type = VDEV_TYPE_RAIDZ, /* name of this vdev type */
.vdev_op_leaf = B_FALSE /* not a leaf vdev */
};
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