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mirror_zfs/module/zfs/vdev_raidz.c
Paul Dagnelie ca5777793e Reduce loaded range tree memory usage 
This patch implements a new tree structure for ZFS, and uses it to 
store range trees more efficiently.

The new structure is approximately a B-tree, though there are some 
small differences from the usual characterizations. The tree has core 
nodes and leaf nodes; each contain data elements, which the elements 
in the core nodes acting as separators between its children. The 
difference between core and leaf nodes is that the core nodes have an 
array of children, while leaf nodes don't. Every node in the tree may 
be only partially full; in most cases, they are all at least 50% full 
(in terms of element count) except for the root node, which can be 
less full. Underfull nodes will steal from their neighbors or merge to 
remain full enough, while overfull nodes will split in two. The data 
elements are contained in tree-controlled buffers; they are copied 
into these on insertion, and overwritten on deletion. This means that 
the elements are not independently allocated, which reduces overhead, 
but also means they can't be shared between trees (and also that 
pointers to them are only valid until a side-effectful tree operation 
occurs). The overhead varies based on how dense the tree is, but is 
usually on the order of about 50% of the element size; the per-node 
overheads are very small, and so don't make a significant difference. 
The trees can accept arbitrary records; they accept a size and a 
comparator to allow them to be used for a variety of purposes.

The new trees replace the AVL trees used in the range trees today. 
Currently, the range_seg_t structure contains three 8 byte integers 
of payload and two 24 byte avl_tree_node_ts to handle its storage in 
both an offset-sorted tree and a size-sorted tree (total size: 64 
bytes). In the new model, the range seg structures are usually two 4 
byte integers, but a separate one needs to exist for the size-sorted 
and offset-sorted tree. Between the raw size, the 50% overhead, and 
the double storage, the new btrees are expected to use 8*1.5*2 = 24 
bytes per record, or 33.3% as much memory as the AVL trees (this is 
for the purposes of storing metaslab range trees; for other purposes, 
like scrubs, they use ~50% as much memory).

We reduced the size of the payload in the range segments by teaching 
range trees about starting offsets and shifts; since metaslabs have a 
fixed starting offset, and they all operate in terms of disk sectors, 
we can store the ranges using 4-byte integers as long as the size of 
the metaslab divided by the sector size is less than 2^32. For 512-byte
sectors, this is a 2^41 (or 2TB) metaslab, which with the default
settings corresponds to a 256PB disk. 4k sector disks can handle 
metaslabs up to 2^46 bytes, or 2^63 byte disks. Since we do not 
anticipate disks of this size in the near future, there should be 
almost no cases where metaslabs need 64-byte integers to store their 
ranges. We do still have the capability to store 64-byte integer ranges 
to account for cases where we are storing per-vdev (or per-dnode) trees, 
which could reasonably go above the limits discussed. We also do not 
store fill information in the compact version of the node, since it 
is only used for sorted scrub.

We also optimized the metaslab loading process in various other ways
to offset some inefficiencies in the btree model. While individual
operations (find, insert, remove_from) are faster for the btree than 
they are for the avl tree, remove usually requires a find operation, 
while in the AVL tree model the element itself suffices. Some clever 
changes actually caused an overall speedup in metaslab loading; we use 
approximately 40% less cpu to load metaslabs in our tests on Illumos.

Another memory and performance optimization was achieved by changing 
what is stored in the size-sorted trees. When a disk is heavily 
fragmented, the df algorithm used by default in ZFS will almost always 
find a number of small regions in its initial cursor-based search; it 
will usually only fall back to the size-sorted tree to find larger 
regions. If we increase the size of the cursor-based search slightly, 
and don't store segments that are smaller than a tunable size floor 
in the size-sorted tree, we can further cut memory usage down to 
below 20% of what the AVL trees store. This also results in further 
reductions in CPU time spent loading metaslabs.

The 16KiB size floor was chosen because it results in substantial memory 
usage reduction while not usually resulting in situations where we can't 
find an appropriate chunk with the cursor and are forced to use an 
oversized chunk from the size-sorted tree. In addition, even if we do 
have to use an oversized chunk from the size-sorted tree, the chunk 
would be too small to use for ZIL allocations, so it isn't as big of a 
loss as it might otherwise be. And often, more small allocations will 
follow the initial one, and the cursor search will now find the 
remainder of the chunk we didn't use all of and use it for subsequent 
allocations. Practical testing has shown little or no change in 
fragmentation as a result of this change.

If the size-sorted tree becomes empty while the offset sorted one still 
has entries, it will load all the entries from the offset sorted tree 
and disregard the size floor until it is unloaded again. This operation 
occurs rarely with the default setting, only on incredibly thoroughly 
fragmented pools.

There are some other small changes to zdb to teach it to handle btrees, 
but nothing major.
                                           
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Matt Ahrens <matt@delphix.com>
Reviewed by: Sebastien Roy seb@delphix.com
Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Paul Dagnelie <pcd@delphix.com>
Closes #9181
2019-10-09 10:36:03 -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, 2019 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>
#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); \
}
void
vdev_raidz_map_free(raidz_map_t *rm)
{
int c;
for (c = 0; c < rm->rm_firstdatacol; c++) {
abd_free(rm->rm_col[c].rc_abd);
if (rm->rm_col[c].rc_gdata != NULL)
abd_free(rm->rm_col[c].rc_gdata);
}
for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++)
abd_put(rm->rm_col[c].rc_abd);
if (rm->rm_abd_copy != NULL)
abd_free(rm->rm_abd_copy);
kmem_free(rm, offsetof(raidz_map_t, rm_col[rm->rm_scols]));
}
static void
vdev_raidz_map_free_vsd(zio_t *zio)
{
raidz_map_t *rm = zio->io_vsd;
ASSERT0(rm->rm_freed);
rm->rm_freed = 1;
if (rm->rm_reports == 0)
vdev_raidz_map_free(rm);
}
/*ARGSUSED*/
static void
vdev_raidz_cksum_free(void *arg, size_t ignored)
{
raidz_map_t *rm = arg;
ASSERT3U(rm->rm_reports, >, 0);
if (--rm->rm_reports == 0 && rm->rm_freed != 0)
vdev_raidz_map_free(rm);
}
static void
vdev_raidz_cksum_finish(zio_cksum_report_t *zcr, const abd_t *good_data)
{
raidz_map_t *rm = zcr->zcr_cbdata;
const size_t c = zcr->zcr_cbinfo;
size_t x, offset;
const abd_t *good = NULL;
const abd_t *bad = rm->rm_col[c].rc_abd;
if (good_data == NULL) {
zfs_ereport_finish_checksum(zcr, NULL, NULL, B_FALSE);
return;
}
if (c < rm->rm_firstdatacol) {
/*
* The first time through, calculate the parity blocks for
* the good data (this relies on the fact that the good
* data never changes for a given logical ZIO)
*/
if (rm->rm_col[0].rc_gdata == NULL) {
abd_t *bad_parity[VDEV_RAIDZ_MAXPARITY];
/*
* Set up the rm_col[]s to generate the parity for
* good_data, first saving the parity bufs and
* replacing them with buffers to hold the result.
*/
for (x = 0; x < rm->rm_firstdatacol; x++) {
bad_parity[x] = rm->rm_col[x].rc_abd;
rm->rm_col[x].rc_abd =
rm->rm_col[x].rc_gdata =
abd_alloc_sametype(rm->rm_col[x].rc_abd,
rm->rm_col[x].rc_size);
}
/* fill in the data columns from good_data */
offset = 0;
for (; x < rm->rm_cols; x++) {
abd_put(rm->rm_col[x].rc_abd);
rm->rm_col[x].rc_abd =
abd_get_offset_size((abd_t *)good_data,
offset, rm->rm_col[x].rc_size);
offset += rm->rm_col[x].rc_size;
}
/*
* Construct the parity from the good data.
*/
vdev_raidz_generate_parity(rm);
/* restore everything back to its original state */
for (x = 0; x < rm->rm_firstdatacol; x++)
rm->rm_col[x].rc_abd = bad_parity[x];
offset = 0;
for (x = rm->rm_firstdatacol; x < rm->rm_cols; x++) {
abd_put(rm->rm_col[x].rc_abd);
rm->rm_col[x].rc_abd = abd_get_offset_size(
rm->rm_abd_copy, offset,
rm->rm_col[x].rc_size);
offset += rm->rm_col[x].rc_size;
}
}
ASSERT3P(rm->rm_col[c].rc_gdata, !=, NULL);
good = abd_get_offset_size(rm->rm_col[c].rc_gdata, 0,
rm->rm_col[c].rc_size);
} else {
/* adjust good_data to point at the start of our column */
offset = 0;
for (x = rm->rm_firstdatacol; x < c; x++)
offset += rm->rm_col[x].rc_size;
good = abd_get_offset_size((abd_t *)good_data, offset,
rm->rm_col[c].rc_size);
}
/* we drop the ereport if it ends up that the data was good */
zfs_ereport_finish_checksum(zcr, good, bad, B_TRUE);
abd_put((abd_t *)good);
}
/*
* Invoked indirectly by zfs_ereport_start_checksum(), called
* below when our read operation fails completely. The main point
* is to keep a copy of everything we read from disk, so that at
* vdev_raidz_cksum_finish() time we can compare it with the good data.
*/
static void
vdev_raidz_cksum_report(zio_t *zio, zio_cksum_report_t *zcr, void *arg)
{
size_t c = (size_t)(uintptr_t)arg;
size_t offset;
raidz_map_t *rm = zio->io_vsd;
size_t size;
/* set up the report and bump the refcount */
zcr->zcr_cbdata = rm;
zcr->zcr_cbinfo = c;
zcr->zcr_finish = vdev_raidz_cksum_finish;
zcr->zcr_free = vdev_raidz_cksum_free;
rm->rm_reports++;
ASSERT3U(rm->rm_reports, >, 0);
if (rm->rm_abd_copy != NULL)
return;
/*
* It's the first time we're called for this raidz_map_t, so we need
* to copy the data aside; there's no guarantee that our zio's buffer
* won't be re-used for something else.
*
* Our parity data is already in separate buffers, so there's no need
* to copy them.
*/
size = 0;
for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++)
size += rm->rm_col[c].rc_size;
rm->rm_abd_copy = abd_alloc_for_io(size, B_FALSE);
for (offset = 0, c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
raidz_col_t *col = &rm->rm_col[c];
abd_t *tmp = abd_get_offset_size(rm->rm_abd_copy, offset,
col->rc_size);
abd_copy(tmp, col->rc_abd, col->rc_size);
abd_put(col->rc_abd);
col->rc_abd = tmp;
offset += col->rc_size;
}
ASSERT3U(offset, ==, size);
}
static const zio_vsd_ops_t vdev_raidz_vsd_ops = {
.vsd_free = vdev_raidz_map_free_vsd,
.vsd_cksum_report = vdev_raidz_cksum_report
};
/*
* 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_map_t *rm;
/* 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;
uint64_t off = 0;
/*
* "Quotient": The number of data sectors for this stripe on all but
* the "big column" child vdevs that also contain "remainder" data.
*/
q = s / (dcols - nparity);
/*
* "Remainder": The number of partial stripe data sectors in this I/O.
* This will add a sector to some, but not all, child vdevs.
*/
r = s - q * (dcols - nparity);
/* The number of "big columns" - those which contain remainder data. */
bc = (r == 0 ? 0 : r + nparity);
/*
* The total number of data and parity sectors associated with
* this I/O.
*/
tot = s + nparity * (q + (r == 0 ? 0 : 1));
/* acols: The columns that will be accessed. */
/* scols: The columns that will be accessed or skipped. */
if (q == 0) {
/* Our I/O request doesn't span all child vdevs. */
acols = bc;
scols = MIN(dcols, roundup(bc, nparity + 1));
} else {
acols = dcols;
scols = dcols;
}
ASSERT3U(acols, <=, scols);
rm = kmem_alloc(offsetof(raidz_map_t, rm_col[scols]), KM_SLEEP);
rm->rm_cols = acols;
rm->rm_scols = scols;
rm->rm_bigcols = bc;
rm->rm_skipstart = bc;
rm->rm_missingdata = 0;
rm->rm_missingparity = 0;
rm->rm_firstdatacol = nparity;
rm->rm_abd_copy = NULL;
rm->rm_reports = 0;
rm->rm_freed = 0;
rm->rm_ecksuminjected = 0;
asize = 0;
for (c = 0; c < scols; c++) {
col = f + c;
coff = o;
if (col >= dcols) {
col -= dcols;
coff += 1ULL << ashift;
}
rm->rm_col[c].rc_devidx = col;
rm->rm_col[c].rc_offset = coff;
rm->rm_col[c].rc_abd = NULL;
rm->rm_col[c].rc_gdata = NULL;
rm->rm_col[c].rc_error = 0;
rm->rm_col[c].rc_tried = 0;
rm->rm_col[c].rc_skipped = 0;
if (c >= acols)
rm->rm_col[c].rc_size = 0;
else if (c < bc)
rm->rm_col[c].rc_size = (q + 1) << ashift;
else
rm->rm_col[c].rc_size = q << ashift;
asize += rm->rm_col[c].rc_size;
}
ASSERT3U(asize, ==, tot << ashift);
rm->rm_asize = roundup(asize, (nparity + 1) << ashift);
rm->rm_nskip = roundup(tot, nparity + 1) - tot;
ASSERT3U(rm->rm_asize - asize, ==, rm->rm_nskip << ashift);
ASSERT3U(rm->rm_nskip, <=, nparity);
for (c = 0; c < rm->rm_firstdatacol; c++)
rm->rm_col[c].rc_abd =
abd_alloc_linear(rm->rm_col[c].rc_size, B_FALSE);
rm->rm_col[c].rc_abd = abd_get_offset_size(zio->io_abd, 0,
rm->rm_col[c].rc_size);
off = rm->rm_col[c].rc_size;
for (c = c + 1; c < acols; c++) {
rm->rm_col[c].rc_abd = abd_get_offset_size(zio->io_abd, off,
rm->rm_col[c].rc_size);
off += rm->rm_col[c].rc_size;
}
/*
* If all data stored spans all columns, there's a danger that parity
* will always be on the same device and, since parity isn't read
* during normal operation, that device's I/O bandwidth won't be
* used effectively. We therefore switch the parity every 1MB.
*
* ... at least that was, ostensibly, the theory. As a practical
* matter unless we juggle the parity between all devices evenly, we
* won't see any benefit. Further, occasional writes that aren't a
* multiple of the LCM of the number of children and the minimum
* stripe width are sufficient to avoid pessimal behavior.
* Unfortunately, this decision created an implicit on-disk format
* requirement that we need to support for all eternity, but only
* for single-parity RAID-Z.
*
* If we intend to skip a sector in the zeroth column for padding
* we must make sure to note this swap. We will never intend to
* skip the first column since at least one data and one parity
* column must appear in each row.
*/
ASSERT(rm->rm_cols >= 2);
ASSERT(rm->rm_col[0].rc_size == rm->rm_col[1].rc_size);
if (rm->rm_firstdatacol == 1 && (zio->io_offset & (1ULL << 20))) {
devidx = rm->rm_col[0].rc_devidx;
o = rm->rm_col[0].rc_offset;
rm->rm_col[0].rc_devidx = rm->rm_col[1].rc_devidx;
rm->rm_col[0].rc_offset = rm->rm_col[1].rc_offset;
rm->rm_col[1].rc_devidx = devidx;
rm->rm_col[1].rc_offset = o;
if (rm->rm_skipstart == 0)
rm->rm_skipstart = 1;
}
zio->io_vsd = rm;
zio->io_vsd_ops = &vdev_raidz_vsd_ops;
/* 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_map_t *rm)
{
uint64_t *p;
int c;
abd_t *src;
for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
src = rm->rm_col[c].rc_abd;
p = abd_to_buf(rm->rm_col[VDEV_RAIDZ_P].rc_abd);
if (c == rm->rm_firstdatacol) {
abd_copy_to_buf(p, src, rm->rm_col[c].rc_size);
} else {
struct pqr_struct pqr = { p, NULL, NULL };
(void) abd_iterate_func(src, 0, rm->rm_col[c].rc_size,
vdev_raidz_p_func, &pqr);
}
}
}
static void
vdev_raidz_generate_parity_pq(raidz_map_t *rm)
{
uint64_t *p, *q, pcnt, ccnt, mask, i;
int c;
abd_t *src;
pcnt = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (p[0]);
ASSERT(rm->rm_col[VDEV_RAIDZ_P].rc_size ==
rm->rm_col[VDEV_RAIDZ_Q].rc_size);
for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
src = rm->rm_col[c].rc_abd;
p = abd_to_buf(rm->rm_col[VDEV_RAIDZ_P].rc_abd);
q = abd_to_buf(rm->rm_col[VDEV_RAIDZ_Q].rc_abd);
ccnt = rm->rm_col[c].rc_size / sizeof (p[0]);
if (c == rm->rm_firstdatacol) {
ASSERT(ccnt == pcnt || ccnt == 0);
abd_copy_to_buf(p, src, rm->rm_col[c].rc_size);
(void) memcpy(q, p, rm->rm_col[c].rc_size);
for (i = ccnt; i < pcnt; i++) {
p[i] = 0;
q[i] = 0;
}
} else {
struct pqr_struct pqr = { p, q, NULL };
ASSERT(ccnt <= pcnt);
(void) abd_iterate_func(src, 0, rm->rm_col[c].rc_size,
vdev_raidz_pq_func, &pqr);
/*
* Treat short columns as though they are full of 0s.
* Note that there's therefore nothing needed for P.
*/
for (i = ccnt; i < pcnt; i++) {
VDEV_RAIDZ_64MUL_2(q[i], mask);
}
}
}
}
static void
vdev_raidz_generate_parity_pqr(raidz_map_t *rm)
{
uint64_t *p, *q, *r, pcnt, ccnt, mask, i;
int c;
abd_t *src;
pcnt = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (p[0]);
ASSERT(rm->rm_col[VDEV_RAIDZ_P].rc_size ==
rm->rm_col[VDEV_RAIDZ_Q].rc_size);
ASSERT(rm->rm_col[VDEV_RAIDZ_P].rc_size ==
rm->rm_col[VDEV_RAIDZ_R].rc_size);
for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
src = rm->rm_col[c].rc_abd;
p = abd_to_buf(rm->rm_col[VDEV_RAIDZ_P].rc_abd);
q = abd_to_buf(rm->rm_col[VDEV_RAIDZ_Q].rc_abd);
r = abd_to_buf(rm->rm_col[VDEV_RAIDZ_R].rc_abd);
ccnt = rm->rm_col[c].rc_size / sizeof (p[0]);
if (c == rm->rm_firstdatacol) {
ASSERT(ccnt == pcnt || ccnt == 0);
abd_copy_to_buf(p, src, rm->rm_col[c].rc_size);
(void) memcpy(q, p, rm->rm_col[c].rc_size);
(void) memcpy(r, p, rm->rm_col[c].rc_size);
for (i = ccnt; i < pcnt; i++) {
p[i] = 0;
q[i] = 0;
r[i] = 0;
}
} else {
struct pqr_struct pqr = { p, q, r };
ASSERT(ccnt <= pcnt);
(void) abd_iterate_func(src, 0, rm->rm_col[c].rc_size,
vdev_raidz_pqr_func, &pqr);
/*
* Treat short columns as though they are full of 0s.
* Note that there's therefore nothing needed for P.
*/
for (i = ccnt; i < pcnt; i++) {
VDEV_RAIDZ_64MUL_2(q[i], mask);
VDEV_RAIDZ_64MUL_4(r[i], mask);
}
}
}
}
/*
* Generate RAID parity in the first virtual columns according to the number of
* parity columns available.
*/
void
vdev_raidz_generate_parity(raidz_map_t *rm)
{
/* Generate using the new math implementation */
if (vdev_raidz_math_generate(rm) != RAIDZ_ORIGINAL_IMPL)
return;
switch (rm->rm_firstdatacol) {
case 1:
vdev_raidz_generate_parity_p(rm);
break;
case 2:
vdev_raidz_generate_parity_pq(rm);
break;
case 3:
vdev_raidz_generate_parity_pqr(rm);
break;
default:
cmn_err(CE_PANIC, "invalid RAID-Z configuration");
}
}
/* ARGSUSED */
static int
vdev_raidz_reconst_p_func(void *dbuf, void *sbuf, size_t size, void *private)
{
uint64_t *dst = dbuf;
uint64_t *src = sbuf;
int cnt = size / sizeof (src[0]);
for (int i = 0; i < cnt; i++) {
dst[i] ^= src[i];
}
return (0);
}
/* ARGSUSED */
static int
vdev_raidz_reconst_q_pre_func(void *dbuf, void *sbuf, size_t size,
void *private)
{
uint64_t *dst = dbuf;
uint64_t *src = sbuf;
uint64_t mask;
int cnt = size / sizeof (dst[0]);
for (int i = 0; i < cnt; i++, dst++, src++) {
VDEV_RAIDZ_64MUL_2(*dst, mask);
*dst ^= *src;
}
return (0);
}
/* ARGSUSED */
static int
vdev_raidz_reconst_q_pre_tail_func(void *buf, size_t size, void *private)
{
uint64_t *dst = buf;
uint64_t mask;
int cnt = size / sizeof (dst[0]);
for (int i = 0; i < cnt; i++, dst++) {
/* same operation as vdev_raidz_reconst_q_pre_func() on dst */
VDEV_RAIDZ_64MUL_2(*dst, mask);
}
return (0);
}
struct reconst_q_struct {
uint64_t *q;
int exp;
};
static int
vdev_raidz_reconst_q_post_func(void *buf, size_t size, void *private)
{
struct reconst_q_struct *rq = private;
uint64_t *dst = buf;
int cnt = size / sizeof (dst[0]);
for (int i = 0; i < cnt; i++, dst++, rq->q++) {
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 int
vdev_raidz_reconstruct_p(raidz_map_t *rm, int *tgts, int ntgts)
{
int x = tgts[0];
int c;
abd_t *dst, *src;
ASSERT(ntgts == 1);
ASSERT(x >= rm->rm_firstdatacol);
ASSERT(x < rm->rm_cols);
ASSERT(rm->rm_col[x].rc_size <= rm->rm_col[VDEV_RAIDZ_P].rc_size);
ASSERT(rm->rm_col[x].rc_size > 0);
src = rm->rm_col[VDEV_RAIDZ_P].rc_abd;
dst = rm->rm_col[x].rc_abd;
abd_copy_from_buf(dst, abd_to_buf(src), rm->rm_col[x].rc_size);
for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
uint64_t size = MIN(rm->rm_col[x].rc_size,
rm->rm_col[c].rc_size);
src = rm->rm_col[c].rc_abd;
dst = rm->rm_col[x].rc_abd;
if (c == x)
continue;
(void) abd_iterate_func2(dst, src, 0, 0, size,
vdev_raidz_reconst_p_func, NULL);
}
return (1 << VDEV_RAIDZ_P);
}
static int
vdev_raidz_reconstruct_q(raidz_map_t *rm, int *tgts, int ntgts)
{
int x = tgts[0];
int c, exp;
abd_t *dst, *src;
ASSERT(ntgts == 1);
ASSERT(rm->rm_col[x].rc_size <= rm->rm_col[VDEV_RAIDZ_Q].rc_size);
for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
uint64_t size = (c == x) ? 0 : MIN(rm->rm_col[x].rc_size,
rm->rm_col[c].rc_size);
src = rm->rm_col[c].rc_abd;
dst = rm->rm_col[x].rc_abd;
if (c == rm->rm_firstdatacol) {
abd_copy(dst, src, size);
if (rm->rm_col[x].rc_size > size)
abd_zero_off(dst, size,
rm->rm_col[x].rc_size - size);
} else {
ASSERT3U(size, <=, rm->rm_col[x].rc_size);
(void) abd_iterate_func2(dst, src, 0, 0, size,
vdev_raidz_reconst_q_pre_func, NULL);
(void) abd_iterate_func(dst,
size, rm->rm_col[x].rc_size - size,
vdev_raidz_reconst_q_pre_tail_func, NULL);
}
}
src = rm->rm_col[VDEV_RAIDZ_Q].rc_abd;
dst = rm->rm_col[x].rc_abd;
exp = 255 - (rm->rm_cols - 1 - x);
struct reconst_q_struct rq = { abd_to_buf(src), exp };
(void) abd_iterate_func(dst, 0, rm->rm_col[x].rc_size,
vdev_raidz_reconst_q_post_func, &rq);
return (1 << VDEV_RAIDZ_Q);
}
static int
vdev_raidz_reconstruct_pq(raidz_map_t *rm, int *tgts, int ntgts)
{
uint8_t *p, *q, *pxy, *qxy, tmp, a, b, aexp, bexp;
abd_t *pdata, *qdata;
uint64_t xsize, ysize;
int x = tgts[0];
int y = tgts[1];
abd_t *xd, *yd;
ASSERT(ntgts == 2);
ASSERT(x < y);
ASSERT(x >= rm->rm_firstdatacol);
ASSERT(y < rm->rm_cols);
ASSERT(rm->rm_col[x].rc_size >= rm->rm_col[y].rc_size);
/*
* Move the parity data aside -- we're going to compute parity as
* though columns x and y were full of zeros -- Pxy and Qxy. We want to
* reuse the parity generation mechanism without trashing the actual
* parity so we make those columns appear to be full of zeros by
* setting their lengths to zero.
*/
pdata = rm->rm_col[VDEV_RAIDZ_P].rc_abd;
qdata = rm->rm_col[VDEV_RAIDZ_Q].rc_abd;
xsize = rm->rm_col[x].rc_size;
ysize = rm->rm_col[y].rc_size;
rm->rm_col[VDEV_RAIDZ_P].rc_abd =
abd_alloc_linear(rm->rm_col[VDEV_RAIDZ_P].rc_size, B_TRUE);
rm->rm_col[VDEV_RAIDZ_Q].rc_abd =
abd_alloc_linear(rm->rm_col[VDEV_RAIDZ_Q].rc_size, B_TRUE);
rm->rm_col[x].rc_size = 0;
rm->rm_col[y].rc_size = 0;
vdev_raidz_generate_parity_pq(rm);
rm->rm_col[x].rc_size = xsize;
rm->rm_col[y].rc_size = ysize;
p = abd_to_buf(pdata);
q = abd_to_buf(qdata);
pxy = abd_to_buf(rm->rm_col[VDEV_RAIDZ_P].rc_abd);
qxy = abd_to_buf(rm->rm_col[VDEV_RAIDZ_Q].rc_abd);
xd = rm->rm_col[x].rc_abd;
yd = rm->rm_col[y].rc_abd;
/*
* We now have:
* Pxy = P + D_x + D_y
* Qxy = Q + 2^(ndevs - 1 - x) * D_x + 2^(ndevs - 1 - y) * D_y
*
* We can then solve for D_x:
* D_x = A * (P + Pxy) + B * (Q + Qxy)
* where
* A = 2^(x - y) * (2^(x - y) + 1)^-1
* B = 2^(ndevs - 1 - x) * (2^(x - y) + 1)^-1
*
* With D_x in hand, we can easily solve for D_y:
* D_y = P + Pxy + D_x
*/
a = vdev_raidz_pow2[255 + x - y];
b = vdev_raidz_pow2[255 - (rm->rm_cols - 1 - x)];
tmp = 255 - vdev_raidz_log2[a ^ 1];
aexp = vdev_raidz_log2[vdev_raidz_exp2(a, tmp)];
bexp = vdev_raidz_log2[vdev_raidz_exp2(b, tmp)];
ASSERT3U(xsize, >=, ysize);
struct reconst_pq_struct rpq = { p, q, pxy, qxy, aexp, bexp };
(void) abd_iterate_func2(xd, yd, 0, 0, ysize,
vdev_raidz_reconst_pq_func, &rpq);
(void) abd_iterate_func(xd, ysize, xsize - ysize,
vdev_raidz_reconst_pq_tail_func, &rpq);
abd_free(rm->rm_col[VDEV_RAIDZ_P].rc_abd);
abd_free(rm->rm_col[VDEV_RAIDZ_Q].rc_abd);
/*
* Restore the saved parity data.
*/
rm->rm_col[VDEV_RAIDZ_P].rc_abd = pdata;
rm->rm_col[VDEV_RAIDZ_Q].rc_abd = qdata;
return ((1 << VDEV_RAIDZ_P) | (1 << VDEV_RAIDZ_Q));
}
/* BEGIN CSTYLED */
/*
* In the general case of reconstruction, we must solve the system of linear
* equations defined by the coeffecients used to generate parity as well as
* the contents of the data and parity disks. This can be expressed with
* vectors for the original data (D) and the actual data (d) and parity (p)
* and a matrix composed of the identity matrix (I) and a dispersal matrix (V):
*
* __ __ __ __
* | | __ __ | p_0 |
* | V | | D_0 | | p_m-1 |
* | | x | : | = | d_0 |
* | I | | D_n-1 | | : |
* | | ~~ ~~ | d_n-1 |
* ~~ ~~ ~~ ~~
*
* I is simply a square identity matrix of size n, and V is a vandermonde
* matrix defined by the coeffecients we chose for the various parity columns
* (1, 2, 4). Note that these values were chosen both for simplicity, speedy
* computation as well as linear separability.
*
* __ __ __ __
* | 1 .. 1 1 1 | | p_0 |
* | 2^n-1 .. 4 2 1 | __ __ | : |
* | 4^n-1 .. 16 4 1 | | D_0 | | p_m-1 |
* | 1 .. 0 0 0 | | D_1 | | d_0 |
* | 0 .. 0 0 0 | x | D_2 | = | d_1 |
* | : : : : | | : | | d_2 |
* | 0 .. 1 0 0 | | D_n-1 | | : |
* | 0 .. 0 1 0 | ~~ ~~ | : |
* | 0 .. 0 0 1 | | d_n-1 |
* ~~ ~~ ~~ ~~
*
* Note that I, V, d, and p are known. To compute D, we must invert the
* matrix and use the known data and parity values to reconstruct the unknown
* data values. We begin by removing the rows in V|I and d|p that correspond
* to failed or missing columns; we then make V|I square (n x n) and d|p
* sized n by removing rows corresponding to unused parity from the bottom up
* to generate (V|I)' and (d|p)'. We can then generate the inverse of (V|I)'
* using Gauss-Jordan elimination. In the example below we use m=3 parity
* columns, n=8 data columns, with errors in d_1, d_2, and p_1:
* __ __
* | 1 1 1 1 1 1 1 1 |
* | 128 64 32 16 8 4 2 1 | <-----+-+-- missing disks
* | 19 205 116 29 64 16 4 1 | / /
* | 1 0 0 0 0 0 0 0 | / /
* | 0 1 0 0 0 0 0 0 | <--' /
* (V|I) = | 0 0 1 0 0 0 0 0 | <---'
* | 0 0 0 1 0 0 0 0 |
* | 0 0 0 0 1 0 0 0 |
* | 0 0 0 0 0 1 0 0 |
* | 0 0 0 0 0 0 1 0 |
* | 0 0 0 0 0 0 0 1 |
* ~~ ~~
* __ __
* | 1 1 1 1 1 1 1 1 |
* | 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_map_t *rm, int n, int nmap, int *map,
uint8_t **rows)
{
int i, j;
int pow;
ASSERT(n == rm->rm_cols - rm->rm_firstdatacol);
/*
* Fill in the missing rows of interest.
*/
for (i = 0; i < nmap; i++) {
ASSERT3S(0, <=, map[i]);
ASSERT3S(map[i], <=, 2);
pow = map[i] * n;
if (pow > 255)
pow -= 255;
ASSERT(pow <= 255);
for (j = 0; j < n; j++) {
pow -= map[i];
if (pow < 0)
pow += 255;
rows[i][j] = vdev_raidz_pow2[pow];
}
}
}
static void
vdev_raidz_matrix_invert(raidz_map_t *rm, int n, int nmissing, int *missing,
uint8_t **rows, uint8_t **invrows, const uint8_t *used)
{
int i, j, ii, jj;
uint8_t log;
/*
* Assert that the first nmissing entries from the array of used
* columns correspond to parity columns and that subsequent entries
* correspond to data columns.
*/
for (i = 0; i < nmissing; i++) {
ASSERT3S(used[i], <, rm->rm_firstdatacol);
}
for (; i < n; i++) {
ASSERT3S(used[i], >=, rm->rm_firstdatacol);
}
/*
* First initialize the storage where we'll compute the inverse rows.
*/
for (i = 0; i < nmissing; i++) {
for (j = 0; j < n; j++) {
invrows[i][j] = (i == j) ? 1 : 0;
}
}
/*
* Subtract all trivial rows from the rows of consequence.
*/
for (i = 0; i < nmissing; i++) {
for (j = nmissing; j < n; j++) {
ASSERT3U(used[j], >=, rm->rm_firstdatacol);
jj = used[j] - rm->rm_firstdatacol;
ASSERT3S(jj, <, n);
invrows[i][j] = rows[i][jj];
rows[i][jj] = 0;
}
}
/*
* For each of the rows of interest, we must normalize it and subtract
* a multiple of it from the other rows.
*/
for (i = 0; i < nmissing; i++) {
for (j = 0; j < missing[i]; j++) {
ASSERT0(rows[i][j]);
}
ASSERT3U(rows[i][missing[i]], !=, 0);
/*
* Compute the inverse of the first element and multiply each
* element in the row by that value.
*/
log = 255 - vdev_raidz_log2[rows[i][missing[i]]];
for (j = 0; j < n; j++) {
rows[i][j] = vdev_raidz_exp2(rows[i][j], log);
invrows[i][j] = vdev_raidz_exp2(invrows[i][j], log);
}
for (ii = 0; ii < nmissing; ii++) {
if (i == ii)
continue;
ASSERT3U(rows[ii][missing[i]], !=, 0);
log = vdev_raidz_log2[rows[ii][missing[i]]];
for (j = 0; j < n; j++) {
rows[ii][j] ^=
vdev_raidz_exp2(rows[i][j], log);
invrows[ii][j] ^=
vdev_raidz_exp2(invrows[i][j], log);
}
}
}
/*
* Verify that the data that is left in the rows are properly part of
* an identity matrix.
*/
for (i = 0; i < nmissing; i++) {
for (j = 0; j < n; j++) {
if (j == missing[i]) {
ASSERT3U(rows[i][j], ==, 1);
} else {
ASSERT0(rows[i][j]);
}
}
}
}
static void
vdev_raidz_matrix_reconstruct(raidz_map_t *rm, int n, int nmissing,
int *missing, uint8_t **invrows, const uint8_t *used)
{
int i, j, x, cc, c;
uint8_t *src;
uint64_t ccount;
uint8_t *dst[VDEV_RAIDZ_MAXPARITY] = { 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, <, rm->rm_cols);
src = abd_to_buf(rm->rm_col[c].rc_abd);
ccount = rm->rm_col[c].rc_size;
for (j = 0; j < nmissing; j++) {
cc = missing[j] + rm->rm_firstdatacol;
ASSERT3U(cc, >=, rm->rm_firstdatacol);
ASSERT3U(cc, <, rm->rm_cols);
ASSERT3U(cc, !=, c);
dst[j] = abd_to_buf(rm->rm_col[cc].rc_abd);
dcount[j] = rm->rm_col[cc].rc_size;
}
ASSERT(ccount >= rm->rm_col[missing[0]].rc_size || i > 0);
for (x = 0; x < ccount; x++, src++) {
if (*src != 0)
log = vdev_raidz_log2[*src];
for (cc = 0; cc < nmissing; cc++) {
if (x >= dcount[cc])
continue;
if (*src == 0) {
val = 0;
} else {
if ((ll = log + invlog[cc][i]) >= 255)
ll -= 255;
val = vdev_raidz_pow2[ll];
}
if (i == 0)
dst[cc][x] = val;
else
dst[cc][x] ^= val;
}
}
}
kmem_free(p, psize);
}
static int
vdev_raidz_reconstruct_general(raidz_map_t *rm, int *tgts, int ntgts)
{
int n, i, c, t, tt;
int nmissing_rows;
int missing_rows[VDEV_RAIDZ_MAXPARITY];
int parity_map[VDEV_RAIDZ_MAXPARITY];
uint8_t *p, *pp;
size_t psize;
uint8_t *rows[VDEV_RAIDZ_MAXPARITY];
uint8_t *invrows[VDEV_RAIDZ_MAXPARITY];
uint8_t *used;
abd_t **bufs = NULL;
int code = 0;
/*
* Matrix reconstruction can't use scatter ABDs yet, so we allocate
* temporary linear ABDs.
*/
if (!abd_is_linear(rm->rm_col[rm->rm_firstdatacol].rc_abd)) {
bufs = kmem_alloc(rm->rm_cols * sizeof (abd_t *), KM_PUSHPAGE);
for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
raidz_col_t *col = &rm->rm_col[c];
bufs[c] = col->rc_abd;
col->rc_abd = abd_alloc_linear(col->rc_size, B_TRUE);
abd_copy(col->rc_abd, bufs[c], col->rc_size);
}
}
n = rm->rm_cols - rm->rm_firstdatacol;
/*
* Figure out which data columns are missing.
*/
nmissing_rows = 0;
for (t = 0; t < ntgts; t++) {
if (tgts[t] >= rm->rm_firstdatacol) {
missing_rows[nmissing_rows++] =
tgts[t] - rm->rm_firstdatacol;
}
}
/*
* Figure out which parity columns to use to help generate the missing
* data columns.
*/
for (tt = 0, c = 0, i = 0; i < nmissing_rows; c++) {
ASSERT(tt < ntgts);
ASSERT(c < rm->rm_firstdatacol);
/*
* Skip any targeted parity columns.
*/
if (c == tgts[tt]) {
tt++;
continue;
}
code |= 1 << c;
parity_map[i] = c;
i++;
}
ASSERT(code != 0);
ASSERT3U(code, <, 1 << VDEV_RAIDZ_MAXPARITY);
psize = (sizeof (rows[0][0]) + sizeof (invrows[0][0])) *
nmissing_rows * n + sizeof (used[0]) * n;
p = kmem_alloc(psize, KM_SLEEP);
for (pp = p, i = 0; i < nmissing_rows; i++) {
rows[i] = pp;
pp += n;
invrows[i] = pp;
pp += n;
}
used = pp;
for (i = 0; i < nmissing_rows; i++) {
used[i] = parity_map[i];
}
for (tt = 0, c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
if (tt < nmissing_rows &&
c == missing_rows[tt] + rm->rm_firstdatacol) {
tt++;
continue;
}
ASSERT3S(i, <, n);
used[i] = c;
i++;
}
/*
* Initialize the interesting rows of the matrix.
*/
vdev_raidz_matrix_init(rm, n, nmissing_rows, parity_map, rows);
/*
* Invert the matrix.
*/
vdev_raidz_matrix_invert(rm, n, nmissing_rows, missing_rows, rows,
invrows, used);
/*
* Reconstruct the missing data using the generated matrix.
*/
vdev_raidz_matrix_reconstruct(rm, n, nmissing_rows, missing_rows,
invrows, used);
kmem_free(p, psize);
/*
* copy back from temporary linear abds and free them
*/
if (bufs) {
for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
raidz_col_t *col = &rm->rm_col[c];
abd_copy(bufs[c], col->rc_abd, col->rc_size);
abd_free(col->rc_abd);
col->rc_abd = bufs[c];
}
kmem_free(bufs, rm->rm_cols * sizeof (abd_t *));
}
return (code);
}
int
vdev_raidz_reconstruct(raidz_map_t *rm, const int *t, int nt)
{
int tgts[VDEV_RAIDZ_MAXPARITY], *dt;
int ntgts;
int i, c, ret;
int code;
int nbadparity, nbaddata;
int parity_valid[VDEV_RAIDZ_MAXPARITY];
/*
* The tgts list must already be sorted.
*/
for (i = 1; i < nt; i++) {
ASSERT(t[i] > t[i - 1]);
}
nbadparity = rm->rm_firstdatacol;
nbaddata = rm->rm_cols - nbadparity;
ntgts = 0;
for (i = 0, c = 0; c < rm->rm_cols; c++) {
if (c < rm->rm_firstdatacol)
parity_valid[c] = B_FALSE;
if (i < nt && c == t[i]) {
tgts[ntgts++] = c;
i++;
} else if (rm->rm_col[c].rc_error != 0) {
tgts[ntgts++] = c;
} else if (c >= rm->rm_firstdatacol) {
nbaddata--;
} else {
parity_valid[c] = B_TRUE;
nbadparity--;
}
}
ASSERT(ntgts >= nt);
ASSERT(nbaddata >= 0);
ASSERT(nbaddata + nbadparity == ntgts);
dt = &tgts[nbadparity];
/* Reconstruct using the new math implementation */
ret = vdev_raidz_math_reconstruct(rm, parity_valid, dt, nbaddata);
if (ret != RAIDZ_ORIGINAL_IMPL)
return (ret);
/*
* See if we can use any of our optimized reconstruction routines.
*/
switch (nbaddata) {
case 1:
if (parity_valid[VDEV_RAIDZ_P])
return (vdev_raidz_reconstruct_p(rm, dt, 1));
ASSERT(rm->rm_firstdatacol > 1);
if (parity_valid[VDEV_RAIDZ_Q])
return (vdev_raidz_reconstruct_q(rm, dt, 1));
ASSERT(rm->rm_firstdatacol > 2);
break;
case 2:
ASSERT(rm->rm_firstdatacol > 1);
if (parity_valid[VDEV_RAIDZ_P] &&
parity_valid[VDEV_RAIDZ_Q])
return (vdev_raidz_reconstruct_pq(rm, dt, 2));
ASSERT(rm->rm_firstdatacol > 2);
break;
}
code = vdev_raidz_reconstruct_general(rm, tgts, ntgts);
ASSERT(code < (1 << VDEV_RAIDZ_MAXPARITY));
ASSERT(code > 0);
return (code);
}
static int
vdev_raidz_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
uint64_t *ashift)
{
vdev_t *cvd;
uint64_t nparity = vd->vdev_nparity;
int c;
int lasterror = 0;
int numerrors = 0;
ASSERT(nparity > 0);
if (nparity > VDEV_RAIDZ_MAXPARITY ||
vd->vdev_children < nparity + 1) {
vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
return (SET_ERROR(EINVAL));
}
vdev_open_children(vd);
for (c = 0; c < vd->vdev_children; c++) {
cvd = vd->vdev_child[c];
if (cvd->vdev_open_error != 0) {
lasterror = cvd->vdev_open_error;
numerrors++;
continue;
}
*asize = MIN(*asize - 1, cvd->vdev_asize - 1) + 1;
*max_asize = MIN(*max_asize - 1, cvd->vdev_max_asize - 1) + 1;
*ashift = MAX(*ashift, cvd->vdev_ashift);
}
*asize *= vd->vdev_children;
*max_asize *= vd->vdev_children;
if (numerrors > nparity) {
vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
return (lasterror);
}
return (0);
}
static void
vdev_raidz_close(vdev_t *vd)
{
int c;
for (c = 0; c < vd->vdev_children; c++)
vdev_close(vd->vdev_child[c]);
}
static uint64_t
vdev_raidz_asize(vdev_t *vd, uint64_t psize)
{
uint64_t asize;
uint64_t ashift = vd->vdev_top->vdev_ashift;
uint64_t cols = vd->vdev_children;
uint64_t nparity = vd->vdev_nparity;
asize = ((psize - 1) >> ashift) + 1;
asize += nparity * ((asize + cols - nparity - 1) / (cols - nparity));
asize = roundup(asize, nparity + 1) << ashift;
return (asize);
}
static void
vdev_raidz_child_done(zio_t *zio)
{
raidz_col_t *rc = zio->io_private;
rc->rc_error = zio->io_error;
rc->rc_tried = 1;
rc->rc_skipped = 0;
}
static void
vdev_raidz_io_verify(zio_t *zio, raidz_map_t *rm, int col)
{
#ifdef ZFS_DEBUG
vdev_t *vd = zio->io_vd;
vdev_t *tvd = vd->vdev_top;
range_seg64_t logical_rs, physical_rs;
logical_rs.rs_start = zio->io_offset;
logical_rs.rs_end = logical_rs.rs_start +
vdev_raidz_asize(zio->io_vd, zio->io_size);
raidz_col_t *rc = &rm->rm_col[col];
vdev_t *cvd = vd->vdev_child[rc->rc_devidx];
vdev_xlate(cvd, &logical_rs, &physical_rs);
ASSERT3U(rc->rc_offset, ==, physical_rs.rs_start);
ASSERT3U(rc->rc_offset, <, physical_rs.rs_end);
/*
* It would be nice to assert that rs_end is equal
* to rc_offset + rc_size but there might be an
* optional I/O at the end that is not accounted in
* rc_size.
*/
if (physical_rs.rs_end > rc->rc_offset + rc->rc_size) {
ASSERT3U(physical_rs.rs_end, ==, rc->rc_offset +
rc->rc_size + (1 << tvd->vdev_ashift));
} else {
ASSERT3U(physical_rs.rs_end, ==, rc->rc_offset + rc->rc_size);
}
#endif
}
/*
* Start an IO operation on a RAIDZ VDev
*
* Outline:
* - For write operations:
* 1. Generate the parity data
* 2. Create child zio write operations to each column's vdev, for both
* data and parity.
* 3. If the column skips any sectors for padding, create optional dummy
* write zio children for those areas to improve aggregation continuity.
* - For read operations:
* 1. Create child zio read operations to each data column's vdev to read
* the range of data required for zio.
* 2. If this is a scrub or resilver operation, or if any of the data
* vdevs have had errors, then create zio read operations to the parity
* columns' VDevs as well.
*/
static void
vdev_raidz_io_start(zio_t *zio)
{
vdev_t *vd = zio->io_vd;
vdev_t *tvd = vd->vdev_top;
vdev_t *cvd;
raidz_map_t *rm;
raidz_col_t *rc;
int c, i;
rm = vdev_raidz_map_alloc(zio, tvd->vdev_ashift, vd->vdev_children,
vd->vdev_nparity);
ASSERT3U(rm->rm_asize, ==, vdev_psize_to_asize(vd, zio->io_size));
if (zio->io_type == ZIO_TYPE_WRITE) {
vdev_raidz_generate_parity(rm);
for (c = 0; c < rm->rm_cols; c++) {
rc = &rm->rm_col[c];
cvd = vd->vdev_child[rc->rc_devidx];
/*
* Verify physical to logical translation.
*/
vdev_raidz_io_verify(zio, rm, c);
zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
rc->rc_offset, rc->rc_abd, rc->rc_size,
zio->io_type, zio->io_priority, 0,
vdev_raidz_child_done, rc));
}
/*
* Generate optional I/Os for any skipped sectors to improve
* aggregation contiguity.
*/
for (c = rm->rm_skipstart, i = 0; i < rm->rm_nskip; c++, i++) {
ASSERT(c <= rm->rm_scols);
if (c == rm->rm_scols)
c = 0;
rc = &rm->rm_col[c];
cvd = vd->vdev_child[rc->rc_devidx];
zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
rc->rc_offset + rc->rc_size, NULL,
1 << tvd->vdev_ashift,
zio->io_type, zio->io_priority,
ZIO_FLAG_NODATA | ZIO_FLAG_OPTIONAL, NULL, NULL));
}
zio_execute(zio);
return;
}
ASSERT(zio->io_type == ZIO_TYPE_READ);
/*
* Iterate over the columns in reverse order so that we hit the parity
* last -- any errors along the way will force us to read the parity.
*/
for (c = rm->rm_cols - 1; c >= 0; c--) {
rc = &rm->rm_col[c];
cvd = vd->vdev_child[rc->rc_devidx];
if (!vdev_readable(cvd)) {
if (c >= rm->rm_firstdatacol)
rm->rm_missingdata++;
else
rm->rm_missingparity++;
rc->rc_error = SET_ERROR(ENXIO);
rc->rc_tried = 1; /* don't even try */
rc->rc_skipped = 1;
continue;
}
if (vdev_dtl_contains(cvd, DTL_MISSING, zio->io_txg, 1)) {
if (c >= rm->rm_firstdatacol)
rm->rm_missingdata++;
else
rm->rm_missingparity++;
rc->rc_error = SET_ERROR(ESTALE);
rc->rc_skipped = 1;
continue;
}
if (c >= rm->rm_firstdatacol || rm->rm_missingdata > 0 ||
(zio->io_flags & (ZIO_FLAG_SCRUB | ZIO_FLAG_RESILVER))) {
zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
rc->rc_offset, rc->rc_abd, rc->rc_size,
zio->io_type, zio->io_priority, 0,
vdev_raidz_child_done, rc));
}
}
zio_execute(zio);
}
/*
* Report a checksum error for a child of a RAID-Z device.
*/
static void
raidz_checksum_error(zio_t *zio, raidz_col_t *rc, abd_t *bad_data)
{
vdev_t *vd = zio->io_vd->vdev_child[rc->rc_devidx];
if (!(zio->io_flags & ZIO_FLAG_SPECULATIVE)) {
zio_bad_cksum_t zbc;
raidz_map_t *rm = zio->io_vsd;
mutex_enter(&vd->vdev_stat_lock);
vd->vdev_stat.vs_checksum_errors++;
mutex_exit(&vd->vdev_stat_lock);
zbc.zbc_has_cksum = 0;
zbc.zbc_injected = rm->rm_ecksuminjected;
zfs_ereport_post_checksum(zio->io_spa, vd,
&zio->io_bookmark, zio, rc->rc_offset, rc->rc_size,
rc->rc_abd, bad_data, &zbc);
}
}
/*
* We keep track of whether or not there were any injected errors, so that
* any ereports we generate can note it.
*/
static int
raidz_checksum_verify(zio_t *zio)
{
zio_bad_cksum_t zbc;
raidz_map_t *rm = zio->io_vsd;
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 such failures.
*/
static int
raidz_parity_verify(zio_t *zio, raidz_map_t *rm)
{
abd_t *orig[VDEV_RAIDZ_MAXPARITY];
int c, ret = 0;
raidz_col_t *rc;
blkptr_t *bp = zio->io_bp;
enum zio_checksum checksum = (bp == NULL ? zio->io_prop.zp_checksum :
(BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER : BP_GET_CHECKSUM(bp)));
if (checksum == ZIO_CHECKSUM_NOPARITY)
return (ret);
for (c = 0; c < rm->rm_firstdatacol; c++) {
rc = &rm->rm_col[c];
if (!rc->rc_tried || rc->rc_error != 0)
continue;
orig[c] = abd_alloc_sametype(rc->rc_abd, rc->rc_size);
abd_copy(orig[c], rc->rc_abd, rc->rc_size);
}
vdev_raidz_generate_parity(rm);
for (c = 0; c < rm->rm_firstdatacol; c++) {
rc = &rm->rm_col[c];
if (!rc->rc_tried || rc->rc_error != 0)
continue;
if (abd_cmp(orig[c], rc->rc_abd) != 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_map_t *rm)
{
int error = 0;
for (int c = 0; c < rm->rm_cols; c++)
error = zio_worst_error(error, rm->rm_col[c].rc_error);
return (error);
}
/*
* Iterate over all combinations of bad data and attempt a reconstruction.
* Note that the algorithm below is non-optimal because it doesn't take into
* account how reconstruction is actually performed. For example, with
* triple-parity RAID-Z the reconstruction procedure is the same if column 4
* is targeted as invalid as if columns 1 and 4 are targeted since in both
* cases we'd only use parity information in column 0.
*/
static int
vdev_raidz_combrec(zio_t *zio, int total_errors, int data_errors)
{
raidz_map_t *rm = zio->io_vsd;
raidz_col_t *rc;
abd_t *orig[VDEV_RAIDZ_MAXPARITY];
int tstore[VDEV_RAIDZ_MAXPARITY + 2];
int *tgts = &tstore[1];
int curr, next, i, c, n;
int code, ret = 0;
ASSERT(total_errors < rm->rm_firstdatacol);
/*
* This simplifies one edge condition.
*/
tgts[-1] = -1;
for (n = 1; n <= rm->rm_firstdatacol - total_errors; n++) {
/*
* Initialize the targets array by finding the first n columns
* that contain no error.
*
* If there were no data errors, we need to ensure that we're
* always explicitly attempting to reconstruct at least one
* data column. To do this, we simply push the highest target
* up into the data columns.
*/
for (c = 0, i = 0; i < n; i++) {
if (i == n - 1 && data_errors == 0 &&
c < rm->rm_firstdatacol) {
c = rm->rm_firstdatacol;
}
while (rm->rm_col[c].rc_error != 0) {
c++;
ASSERT3S(c, <, rm->rm_cols);
}
tgts[i] = c++;
}
/*
* Setting tgts[n] simplifies the other edge condition.
*/
tgts[n] = rm->rm_cols;
/*
* These buffers were allocated in previous iterations.
*/
for (i = 0; i < n - 1; i++) {
ASSERT(orig[i] != NULL);
}
orig[n - 1] = abd_alloc_sametype(rm->rm_col[0].rc_abd,
rm->rm_col[0].rc_size);
curr = 0;
next = tgts[curr];
while (curr != n) {
tgts[curr] = next;
curr = 0;
/*
* Save off the original data that we're going to
* attempt to reconstruct.
*/
for (i = 0; i < n; i++) {
ASSERT(orig[i] != NULL);
c = tgts[i];
ASSERT3S(c, >=, 0);
ASSERT3S(c, <, rm->rm_cols);
rc = &rm->rm_col[c];
abd_copy(orig[i], rc->rc_abd, rc->rc_size);
}
/*
* Attempt a reconstruction and exit the outer loop on
* success.
*/
code = vdev_raidz_reconstruct(rm, tgts, n);
if (raidz_checksum_verify(zio) == 0) {
for (i = 0; i < n; i++) {
c = tgts[i];
rc = &rm->rm_col[c];
ASSERT(rc->rc_error == 0);
if (rc->rc_tried)
raidz_checksum_error(zio, rc,
orig[i]);
rc->rc_error = SET_ERROR(ECKSUM);
}
ret = code;
goto done;
}
/*
* Restore the original data.
*/
for (i = 0; i < n; i++) {
c = tgts[i];
rc = &rm->rm_col[c];
abd_copy(rc->rc_abd, orig[i], rc->rc_size);
}
do {
/*
* Find the next valid column after the curr
* position..
*/
for (next = tgts[curr] + 1;
next < rm->rm_cols &&
rm->rm_col[next].rc_error != 0; next++)
continue;
ASSERT(next <= tgts[curr + 1]);
/*
* If that spot is available, we're done here.
*/
if (next != tgts[curr + 1])
break;
/*
* Otherwise, find the next valid column after
* the previous position.
*/
for (c = tgts[curr - 1] + 1;
rm->rm_col[c].rc_error != 0; c++)
continue;
tgts[curr] = c;
curr++;
} while (curr != n);
}
}
n--;
done:
for (i = 0; i < n; i++)
abd_free(orig[i]);
return (ret);
}
/*
* Complete an IO operation on a RAIDZ VDev
*
* Outline:
* - For write operations:
* 1. Check for errors on the child IOs.
* 2. Return, setting an error code if too few child VDevs were written
* to reconstruct the data later. Note that partial writes are
* considered successful if they can be reconstructed at all.
* - For read operations:
* 1. Check for errors on the child IOs.
* 2. If data errors occurred:
* a. Try to reassemble the data from the parity available.
* b. If we haven't yet read the parity drives, read them now.
* c. If all parity drives have been read but the data still doesn't
* reassemble with a correct checksum, then try combinatorial
* reconstruction.
* d. If that doesn't work, return an error.
* 3. If there were unexpected errors or this is a resilver operation,
* rewrite the vdevs that had errors.
*/
static void
vdev_raidz_io_done(zio_t *zio)
{
vdev_t *vd = zio->io_vd;
vdev_t *cvd;
raidz_map_t *rm = zio->io_vsd;
raidz_col_t *rc = NULL;
int unexpected_errors = 0;
int parity_errors = 0;
int parity_untried = 0;
int data_errors = 0;
int total_errors = 0;
int n, c;
int tgts[VDEV_RAIDZ_MAXPARITY];
int code;
ASSERT(zio->io_bp != NULL); /* XXX need to add code to enforce this */
ASSERT(rm->rm_missingparity <= rm->rm_firstdatacol);
ASSERT(rm->rm_missingdata <= rm->rm_cols - rm->rm_firstdatacol);
for (c = 0; c < rm->rm_cols; c++) {
rc = &rm->rm_col[c];
if (rc->rc_error) {
ASSERT(rc->rc_error != ECKSUM); /* child has no bp */
if (c < rm->rm_firstdatacol)
parity_errors++;
else
data_errors++;
if (!rc->rc_skipped)
unexpected_errors++;
total_errors++;
} else if (c < rm->rm_firstdatacol && !rc->rc_tried) {
parity_untried++;
}
}
if (zio->io_type == ZIO_TYPE_WRITE) {
/*
* XXX -- for now, treat partial writes as a success.
* (If we couldn't write enough columns to reconstruct
* the data, the I/O failed. Otherwise, good enough.)
*
* Now that we support write reallocation, it would be better
* to treat partial failure as real failure unless there are
* no non-degraded top-level vdevs left, and not update DTLs
* if we intend to reallocate.
*/
/* XXPOLICY */
if (total_errors > rm->rm_firstdatacol)
zio->io_error = vdev_raidz_worst_error(rm);
return;
}
ASSERT(zio->io_type == ZIO_TYPE_READ);
/*
* There are three potential phases for a read:
* 1. produce valid data from the columns read
* 2. read all disks and try again
* 3. perform combinatorial reconstruction
*
* Each phase is progressively both more expensive and less likely to
* occur. If we encounter more errors than we can repair or all phases
* fail, we have no choice but to return an error.
*/
/*
* If the number of errors we saw was correctable -- less than or equal
* to the number of parity disks read -- attempt to produce data that
* has a valid checksum. Naturally, this case applies in the absence of
* any errors.
*/
if (total_errors <= rm->rm_firstdatacol - parity_untried) {
if (data_errors == 0) {
if (raidz_checksum_verify(zio) == 0) {
/*
* If we read parity information (unnecessarily
* as it happens since no reconstruction was
* needed) regenerate and verify the parity.
* We also regenerate parity when resilvering
* so we can write it out to the failed device
* later.
*/
if (parity_errors + parity_untried <
rm->rm_firstdatacol ||
(zio->io_flags & ZIO_FLAG_RESILVER)) {
n = raidz_parity_verify(zio, rm);
unexpected_errors += n;
ASSERT(parity_errors + n <=
rm->rm_firstdatacol);
}
goto done;
}
} else {
/*
* We either attempt to read all the parity columns or
* none of them. If we didn't try to read parity, we
* wouldn't be here in the correctable case. There must
* also have been fewer parity errors than parity
* columns or, again, we wouldn't be in this code path.
*/
ASSERT(parity_untried == 0);
ASSERT(parity_errors < rm->rm_firstdatacol);
/*
* Identify the data columns that reported an error.
*/
n = 0;
for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
rc = &rm->rm_col[c];
if (rc->rc_error != 0) {
ASSERT(n < VDEV_RAIDZ_MAXPARITY);
tgts[n++] = c;
}
}
ASSERT(rm->rm_firstdatacol >= n);
code = vdev_raidz_reconstruct(rm, tgts, n);
if (raidz_checksum_verify(zio) == 0) {
/*
* If we read more parity disks than were used
* for reconstruction, confirm that the other
* parity disks produced correct data. This
* routine is suboptimal in that it regenerates
* the parity that we already used in addition
* to the parity that we're attempting to
* verify, but this should be a relatively
* uncommon case, and can be optimized if it
* becomes a problem. Note that we regenerate
* parity when resilvering so we can write it
* out to failed devices later.
*/
if (parity_errors < rm->rm_firstdatacol - n ||
(zio->io_flags & ZIO_FLAG_RESILVER)) {
n = raidz_parity_verify(zio, rm);
unexpected_errors += n;
ASSERT(parity_errors + n <=
rm->rm_firstdatacol);
}
goto done;
}
}
}
/*
* This isn't a typical situation -- either we got a read error or
* a child silently returned bad data. Read every block so we can
* try again with as much data and parity as we can track down. If
* we've already been through once before, all children will be marked
* as tried so we'll proceed to combinatorial reconstruction.
*/
unexpected_errors = 1;
rm->rm_missingdata = 0;
rm->rm_missingparity = 0;
for (c = 0; c < rm->rm_cols; c++) {
if (rm->rm_col[c].rc_tried)
continue;
zio_vdev_io_redone(zio);
do {
rc = &rm->rm_col[c];
if (rc->rc_tried)
continue;
zio_nowait(zio_vdev_child_io(zio, NULL,
vd->vdev_child[rc->rc_devidx],
rc->rc_offset, rc->rc_abd, rc->rc_size,
zio->io_type, zio->io_priority, 0,
vdev_raidz_child_done, rc));
} while (++c < rm->rm_cols);
return;
}
/*
* At this point we've attempted to reconstruct the data given the
* errors we detected, and we've attempted to read all columns. There
* must, therefore, be one or more additional problems -- silent errors
* resulting in invalid data rather than explicit I/O errors resulting
* in absent data. We check if there is enough additional data to
* possibly reconstruct the data and then perform combinatorial
* reconstruction over all possible combinations. If that fails,
* we're cooked.
*/
if (total_errors > rm->rm_firstdatacol) {
zio->io_error = vdev_raidz_worst_error(rm);
} else if (total_errors < rm->rm_firstdatacol &&
(code = vdev_raidz_combrec(zio, total_errors, data_errors)) != 0) {
/*
* If we didn't use all the available parity for the
* combinatorial reconstruction, verify that the remaining
* parity is correct.
*/
if (code != (1 << rm->rm_firstdatacol) - 1)
(void) raidz_parity_verify(zio, rm);
} else {
/*
* We're here because either:
*
* total_errors == rm_first_datacol, or
* vdev_raidz_combrec() failed
*
* In either case, there is enough bad data to prevent
* reconstruction.
*
* Start checksum ereports for all children which haven't
* failed, and the IO wasn't speculative.
*/
zio->io_error = SET_ERROR(ECKSUM);
if (!(zio->io_flags & ZIO_FLAG_SPECULATIVE)) {
for (c = 0; c < rm->rm_cols; c++) {
vdev_t *cvd;
rc = &rm->rm_col[c];
cvd = vd->vdev_child[rc->rc_devidx];
if (rc->rc_error == 0) {
zio_bad_cksum_t zbc;
zbc.zbc_has_cksum = 0;
zbc.zbc_injected =
rm->rm_ecksuminjected;
mutex_enter(&cvd->vdev_stat_lock);
cvd->vdev_stat.vs_checksum_errors++;
mutex_exit(&cvd->vdev_stat_lock);
zfs_ereport_start_checksum(
zio->io_spa, cvd,
&zio->io_bookmark, zio,
rc->rc_offset, rc->rc_size,
(void *)(uintptr_t)c, &zbc);
}
}
}
}
done:
zio_checksum_verified(zio);
if (zio->io_error == 0 && spa_writeable(zio->io_spa) &&
(unexpected_errors || (zio->io_flags & ZIO_FLAG_RESILVER))) {
/*
* Use the good data we have in hand to repair damaged children.
*/
for (c = 0; c < rm->rm_cols; c++) {
rc = &rm->rm_col[c];
cvd = vd->vdev_child[rc->rc_devidx];
if (rc->rc_error == 0)
continue;
zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
rc->rc_offset, rc->rc_abd, rc->rc_size,
ZIO_TYPE_WRITE, ZIO_PRIORITY_ASYNC_WRITE,
ZIO_FLAG_IO_REPAIR | (unexpected_errors ?
ZIO_FLAG_SELF_HEAL : 0), NULL, NULL));
}
}
}
static void
vdev_raidz_state_change(vdev_t *vd, int faulted, int degraded)
{
if (faulted > vd->vdev_nparity)
vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
VDEV_AUX_NO_REPLICAS);
else if (degraded + faulted != 0)
vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
else
vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
}
/*
* Determine if any portion of the provided block resides on a child vdev
* with a dirty DTL and therefore needs to be resilvered. The function
* assumes that at least one DTL is dirty which implies that full stripe
* width blocks must be resilvered.
*/
static boolean_t
vdev_raidz_need_resilver(vdev_t *vd, uint64_t offset, size_t psize)
{
uint64_t dcols = vd->vdev_children;
uint64_t nparity = vd->vdev_nparity;
uint64_t ashift = vd->vdev_top->vdev_ashift;
/* The starting RAIDZ (parent) vdev sector of the block. */
uint64_t b = offset >> ashift;
/* The zio's size in units of the vdev's minimum sector size. */
uint64_t s = ((psize - 1) >> ashift) + 1;
/* The first column for this stripe. */
uint64_t f = b % dcols;
if (s + nparity >= dcols)
return (B_TRUE);
for (uint64_t c = 0; c < s + nparity; c++) {
uint64_t devidx = (f + c) % dcols;
vdev_t *cvd = vd->vdev_child[devidx];
/*
* dsl_scan_need_resilver() already checked vd with
* vdev_dtl_contains(). So here just check cvd with
* vdev_dtl_empty(), cheaper and a good approximation.
*/
if (!vdev_dtl_empty(cvd, DTL_PARTIAL))
return (B_TRUE);
}
return (B_FALSE);
}
static void
vdev_raidz_xlate(vdev_t *cvd, const range_seg64_t *in, range_seg64_t *res)
{
vdev_t *raidvd = cvd->vdev_parent;
ASSERT(raidvd->vdev_ops == &vdev_raidz_ops);
uint64_t width = raidvd->vdev_children;
uint64_t tgt_col = cvd->vdev_id;
uint64_t ashift = raidvd->vdev_top->vdev_ashift;
/* make sure the offsets are block-aligned */
ASSERT0(in->rs_start % (1 << ashift));
ASSERT0(in->rs_end % (1 << ashift));
uint64_t b_start = in->rs_start >> ashift;
uint64_t b_end = in->rs_end >> ashift;
uint64_t start_row = 0;
if (b_start > tgt_col) /* avoid underflow */
start_row = ((b_start - tgt_col - 1) / width) + 1;
uint64_t end_row = 0;
if (b_end > tgt_col)
end_row = ((b_end - tgt_col - 1) / width) + 1;
res->rs_start = start_row << ashift;
res->rs_end = end_row << ashift;
ASSERT3U(res->rs_start, <=, in->rs_start);
ASSERT3U(res->rs_end - res->rs_start, <=, in->rs_end - in->rs_start);
}
vdev_ops_t vdev_raidz_ops = {
.vdev_op_open = vdev_raidz_open,
.vdev_op_close = vdev_raidz_close,
.vdev_op_asize = vdev_raidz_asize,
.vdev_op_io_start = vdev_raidz_io_start,
.vdev_op_io_done = vdev_raidz_io_done,
.vdev_op_state_change = vdev_raidz_state_change,
.vdev_op_need_resilver = vdev_raidz_need_resilver,
.vdev_op_hold = NULL,
.vdev_op_rele = NULL,
.vdev_op_remap = NULL,
.vdev_op_xlate = vdev_raidz_xlate,
.vdev_op_type = VDEV_TYPE_RAIDZ, /* name of this vdev type */
.vdev_op_leaf = B_FALSE /* not a leaf vdev */
};
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