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diff --git a/uts/common/fs/zfs/vdev_raidz.c b/uts/common/fs/zfs/vdev_raidz.c
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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.
+ */
+
+#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/fs/zfs.h>
+#include <sys/fm/fs/zfs.h>
+
+/*
+ * 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 trival
+ * 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.
+ */
+
+typedef struct raidz_col {
+ uint64_t rc_devidx; /* child device index for I/O */
+ uint64_t rc_offset; /* device offset */
+ uint64_t rc_size; /* I/O size */
+ void *rc_data; /* I/O data */
+ void *rc_gdata; /* used to store the "good" version */
+ int rc_error; /* I/O error for this device */
+ uint8_t rc_tried; /* Did we attempt this I/O column? */
+ uint8_t rc_skipped; /* Did we skip this I/O column? */
+} raidz_col_t;
+
+typedef struct raidz_map {
+ uint64_t rm_cols; /* Regular column count */
+ uint64_t rm_scols; /* Count including skipped columns */
+ uint64_t rm_bigcols; /* Number of oversized columns */
+ uint64_t rm_asize; /* Actual total I/O size */
+ uint64_t rm_missingdata; /* Count of missing data devices */
+ uint64_t rm_missingparity; /* Count of missing parity devices */
+ uint64_t rm_firstdatacol; /* First data column/parity count */
+ uint64_t rm_nskip; /* Skipped sectors for padding */
+ uint64_t rm_skipstart; /* Column index of padding start */
+ void *rm_datacopy; /* rm_asize-buffer of copied data */
+ uintptr_t rm_reports; /* # of referencing checksum reports */
+ uint8_t rm_freed; /* map no longer has referencing ZIO */
+ uint8_t rm_ecksuminjected; /* checksum error was injected */
+ raidz_col_t rm_col[1]; /* Flexible array of I/O columns */
+} raidz_map_t;
+
+#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) & 0x1d1d1d1d1d1d1d1d); \
+}
+
+#define VDEV_RAIDZ_64MUL_4(x, mask) \
+{ \
+ VDEV_RAIDZ_64MUL_2((x), mask); \
+ VDEV_RAIDZ_64MUL_2((x), mask); \
+}
+
+/*
+ * Force reconstruction to use the general purpose method.
+ */
+int vdev_raidz_default_to_general;
+
+/*
+ * These two tables represent powers and logs of 2 in the Galois field defined
+ * above. These values were computed by repeatedly multiplying by 2 as above.
+ */
+static const uint8_t vdev_raidz_pow2[256] = {
+ 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80,
+ 0x1d, 0x3a, 0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26,
+ 0x4c, 0x98, 0x2d, 0x5a, 0xb4, 0x75, 0xea, 0xc9,
+ 0x8f, 0x03, 0x06, 0x0c, 0x18, 0x30, 0x60, 0xc0,
+ 0x9d, 0x27, 0x4e, 0x9c, 0x25, 0x4a, 0x94, 0x35,
+ 0x6a, 0xd4, 0xb5, 0x77, 0xee, 0xc1, 0x9f, 0x23,
+ 0x46, 0x8c, 0x05, 0x0a, 0x14, 0x28, 0x50, 0xa0,
+ 0x5d, 0xba, 0x69, 0xd2, 0xb9, 0x6f, 0xde, 0xa1,
+ 0x5f, 0xbe, 0x61, 0xc2, 0x99, 0x2f, 0x5e, 0xbc,
+ 0x65, 0xca, 0x89, 0x0f, 0x1e, 0x3c, 0x78, 0xf0,
+ 0xfd, 0xe7, 0xd3, 0xbb, 0x6b, 0xd6, 0xb1, 0x7f,
+ 0xfe, 0xe1, 0xdf, 0xa3, 0x5b, 0xb6, 0x71, 0xe2,
+ 0xd9, 0xaf, 0x43, 0x86, 0x11, 0x22, 0x44, 0x88,
+ 0x0d, 0x1a, 0x34, 0x68, 0xd0, 0xbd, 0x67, 0xce,
+ 0x81, 0x1f, 0x3e, 0x7c, 0xf8, 0xed, 0xc7, 0x93,
+ 0x3b, 0x76, 0xec, 0xc5, 0x97, 0x33, 0x66, 0xcc,
+ 0x85, 0x17, 0x2e, 0x5c, 0xb8, 0x6d, 0xda, 0xa9,
+ 0x4f, 0x9e, 0x21, 0x42, 0x84, 0x15, 0x2a, 0x54,
+ 0xa8, 0x4d, 0x9a, 0x29, 0x52, 0xa4, 0x55, 0xaa,
+ 0x49, 0x92, 0x39, 0x72, 0xe4, 0xd5, 0xb7, 0x73,
+ 0xe6, 0xd1, 0xbf, 0x63, 0xc6, 0x91, 0x3f, 0x7e,
+ 0xfc, 0xe5, 0xd7, 0xb3, 0x7b, 0xf6, 0xf1, 0xff,
+ 0xe3, 0xdb, 0xab, 0x4b, 0x96, 0x31, 0x62, 0xc4,
+ 0x95, 0x37, 0x6e, 0xdc, 0xa5, 0x57, 0xae, 0x41,
+ 0x82, 0x19, 0x32, 0x64, 0xc8, 0x8d, 0x07, 0x0e,
+ 0x1c, 0x38, 0x70, 0xe0, 0xdd, 0xa7, 0x53, 0xa6,
+ 0x51, 0xa2, 0x59, 0xb2, 0x79, 0xf2, 0xf9, 0xef,
+ 0xc3, 0x9b, 0x2b, 0x56, 0xac, 0x45, 0x8a, 0x09,
+ 0x12, 0x24, 0x48, 0x90, 0x3d, 0x7a, 0xf4, 0xf5,
+ 0xf7, 0xf3, 0xfb, 0xeb, 0xcb, 0x8b, 0x0b, 0x16,
+ 0x2c, 0x58, 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83,
+ 0x1b, 0x36, 0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x01
+};
+static const uint8_t vdev_raidz_log2[256] = {
+ 0x00, 0x00, 0x01, 0x19, 0x02, 0x32, 0x1a, 0xc6,
+ 0x03, 0xdf, 0x33, 0xee, 0x1b, 0x68, 0xc7, 0x4b,
+ 0x04, 0x64, 0xe0, 0x0e, 0x34, 0x8d, 0xef, 0x81,
+ 0x1c, 0xc1, 0x69, 0xf8, 0xc8, 0x08, 0x4c, 0x71,
+ 0x05, 0x8a, 0x65, 0x2f, 0xe1, 0x24, 0x0f, 0x21,
+ 0x35, 0x93, 0x8e, 0xda, 0xf0, 0x12, 0x82, 0x45,
+ 0x1d, 0xb5, 0xc2, 0x7d, 0x6a, 0x27, 0xf9, 0xb9,
+ 0xc9, 0x9a, 0x09, 0x78, 0x4d, 0xe4, 0x72, 0xa6,
+ 0x06, 0xbf, 0x8b, 0x62, 0x66, 0xdd, 0x30, 0xfd,
+ 0xe2, 0x98, 0x25, 0xb3, 0x10, 0x91, 0x22, 0x88,
+ 0x36, 0xd0, 0x94, 0xce, 0x8f, 0x96, 0xdb, 0xbd,
+ 0xf1, 0xd2, 0x13, 0x5c, 0x83, 0x38, 0x46, 0x40,
+ 0x1e, 0x42, 0xb6, 0xa3, 0xc3, 0x48, 0x7e, 0x6e,
+ 0x6b, 0x3a, 0x28, 0x54, 0xfa, 0x85, 0xba, 0x3d,
+ 0xca, 0x5e, 0x9b, 0x9f, 0x0a, 0x15, 0x79, 0x2b,
+ 0x4e, 0xd4, 0xe5, 0xac, 0x73, 0xf3, 0xa7, 0x57,
+ 0x07, 0x70, 0xc0, 0xf7, 0x8c, 0x80, 0x63, 0x0d,
+ 0x67, 0x4a, 0xde, 0xed, 0x31, 0xc5, 0xfe, 0x18,
+ 0xe3, 0xa5, 0x99, 0x77, 0x26, 0xb8, 0xb4, 0x7c,
+ 0x11, 0x44, 0x92, 0xd9, 0x23, 0x20, 0x89, 0x2e,
+ 0x37, 0x3f, 0xd1, 0x5b, 0x95, 0xbc, 0xcf, 0xcd,
+ 0x90, 0x87, 0x97, 0xb2, 0xdc, 0xfc, 0xbe, 0x61,
+ 0xf2, 0x56, 0xd3, 0xab, 0x14, 0x2a, 0x5d, 0x9e,
+ 0x84, 0x3c, 0x39, 0x53, 0x47, 0x6d, 0x41, 0xa2,
+ 0x1f, 0x2d, 0x43, 0xd8, 0xb7, 0x7b, 0xa4, 0x76,
+ 0xc4, 0x17, 0x49, 0xec, 0x7f, 0x0c, 0x6f, 0xf6,
+ 0x6c, 0xa1, 0x3b, 0x52, 0x29, 0x9d, 0x55, 0xaa,
+ 0xfb, 0x60, 0x86, 0xb1, 0xbb, 0xcc, 0x3e, 0x5a,
+ 0xcb, 0x59, 0x5f, 0xb0, 0x9c, 0xa9, 0xa0, 0x51,
+ 0x0b, 0xf5, 0x16, 0xeb, 0x7a, 0x75, 0x2c, 0xd7,
+ 0x4f, 0xae, 0xd5, 0xe9, 0xe6, 0xe7, 0xad, 0xe8,
+ 0x74, 0xd6, 0xf4, 0xea, 0xa8, 0x50, 0x58, 0xaf,
+};
+
+static void vdev_raidz_generate_parity(raidz_map_t *rm);
+
+/*
+ * Multiply a given number by 2 raised to the given power.
+ */
+static uint8_t
+vdev_raidz_exp2(uint_t a, int exp)
+{
+ if (a == 0)
+ return (0);
+
+ ASSERT(exp >= 0);
+ ASSERT(vdev_raidz_log2[a] > 0 || a == 1);
+
+ exp += vdev_raidz_log2[a];
+ if (exp > 255)
+ exp -= 255;
+
+ return (vdev_raidz_pow2[exp]);
+}
+
+static void
+vdev_raidz_map_free(raidz_map_t *rm)
+{
+ int c;
+ size_t size;
+
+ for (c = 0; c < rm->rm_firstdatacol; c++) {
+ zio_buf_free(rm->rm_col[c].rc_data, rm->rm_col[c].rc_size);
+
+ if (rm->rm_col[c].rc_gdata != NULL)
+ zio_buf_free(rm->rm_col[c].rc_gdata,
+ rm->rm_col[c].rc_size);
+ }
+
+ size = 0;
+ for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++)
+ size += rm->rm_col[c].rc_size;
+
+ if (rm->rm_datacopy != NULL)
+ zio_buf_free(rm->rm_datacopy, size);
+
+ 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;
+
+ ASSERT3U(rm->rm_freed, ==, 0);
+ 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 void *good_data)
+{
+ raidz_map_t *rm = zcr->zcr_cbdata;
+ size_t c = zcr->zcr_cbinfo;
+ size_t x;
+
+ const char *good = NULL;
+ const char *bad = rm->rm_col[c].rc_data;
+
+ 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) {
+ char *bad_parity[VDEV_RAIDZ_MAXPARITY];
+ char *buf;
+
+ /*
+ * 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_data;
+ rm->rm_col[x].rc_data = rm->rm_col[x].rc_gdata =
+ zio_buf_alloc(rm->rm_col[x].rc_size);
+ }
+
+ /* fill in the data columns from good_data */
+ buf = (char *)good_data;
+ for (; x < rm->rm_cols; x++) {
+ rm->rm_col[x].rc_data = buf;
+ buf += 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_data = bad_parity[x];
+
+ buf = rm->rm_datacopy;
+ for (x = rm->rm_firstdatacol; x < rm->rm_cols; x++) {
+ rm->rm_col[x].rc_data = buf;
+ buf += rm->rm_col[x].rc_size;
+ }
+ }
+
+ ASSERT3P(rm->rm_col[c].rc_gdata, !=, NULL);
+ good = rm->rm_col[c].rc_gdata;
+ } else {
+ /* adjust good_data to point at the start of our column */
+ good = good_data;
+
+ for (x = rm->rm_firstdatacol; x < c; x++)
+ good += rm->rm_col[x].rc_size;
+ }
+
+ /* we drop the ereport if it ends up that the data was good */
+ zfs_ereport_finish_checksum(zcr, good, bad, B_TRUE);
+}
+
+/*
+ * 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;
+ caddr_t buf;
+
+ 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_datacopy != 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;
+
+ buf = rm->rm_datacopy = zio_buf_alloc(size);
+
+ for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
+ raidz_col_t *col = &rm->rm_col[c];
+
+ bcopy(col->rc_data, buf, col->rc_size);
+ col->rc_data = buf;
+
+ buf += col->rc_size;
+ }
+ ASSERT3P(buf - (caddr_t)rm->rm_datacopy, ==, size);
+}
+
+static const zio_vsd_ops_t vdev_raidz_vsd_ops = {
+ vdev_raidz_map_free_vsd,
+ vdev_raidz_cksum_report
+};
+
+static raidz_map_t *
+vdev_raidz_map_alloc(zio_t *zio, uint64_t unit_shift, uint64_t dcols,
+ uint64_t nparity)
+{
+ raidz_map_t *rm;
+ uint64_t b = zio->io_offset >> unit_shift;
+ uint64_t s = zio->io_size >> unit_shift;
+ uint64_t f = b % dcols;
+ uint64_t o = (b / dcols) << unit_shift;
+ uint64_t q, r, c, bc, col, acols, scols, coff, devidx, asize, tot;
+
+ q = s / (dcols - nparity);
+ r = s - q * (dcols - nparity);
+ bc = (r == 0 ? 0 : r + nparity);
+ tot = s + nparity * (q + (r == 0 ? 0 : 1));
+
+ if (q == 0) {
+ 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_datacopy = 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 << unit_shift;
+ }
+ rm->rm_col[c].rc_devidx = col;
+ rm->rm_col[c].rc_offset = coff;
+ rm->rm_col[c].rc_data = 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) << unit_shift;
+ else
+ rm->rm_col[c].rc_size = q << unit_shift;
+
+ asize += rm->rm_col[c].rc_size;
+ }
+
+ ASSERT3U(asize, ==, tot << unit_shift);
+ rm->rm_asize = roundup(asize, (nparity + 1) << unit_shift);
+ rm->rm_nskip = roundup(tot, nparity + 1) - tot;
+ ASSERT3U(rm->rm_asize - asize, ==, rm->rm_nskip << unit_shift);
+ ASSERT3U(rm->rm_nskip, <=, nparity);
+
+ for (c = 0; c < rm->rm_firstdatacol; c++)
+ rm->rm_col[c].rc_data = zio_buf_alloc(rm->rm_col[c].rc_size);
+
+ rm->rm_col[c].rc_data = zio->io_data;
+
+ for (c = c + 1; c < acols; c++)
+ rm->rm_col[c].rc_data = (char *)rm->rm_col[c - 1].rc_data +
+ rm->rm_col[c - 1].rc_size;
+
+ /*
+ * If all data stored spans all columns, there's a danger that parity
+ * will always be on the same device and, since parity isn't read
+ * during normal operation, that that device's I/O bandwidth won't be
+ * used effectively. We therefore switch the parity every 1MB.
+ *
+ * ... at least that was, ostensibly, the theory. As a practical
+ * matter unless we juggle the parity between all devices evenly, we
+ * won't see any benefit. Further, occasional writes that aren't a
+ * multiple of the LCM of the number of children and the minimum
+ * stripe width are sufficient to avoid pessimal behavior.
+ * Unfortunately, this decision created an implicit on-disk format
+ * requirement that we need to support for all eternity, but only
+ * for single-parity RAID-Z.
+ *
+ * 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;
+ return (rm);
+}
+
+static void
+vdev_raidz_generate_parity_p(raidz_map_t *rm)
+{
+ uint64_t *p, *src, pcount, ccount, i;
+ int c;
+
+ pcount = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (src[0]);
+
+ for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
+ src = rm->rm_col[c].rc_data;
+ p = rm->rm_col[VDEV_RAIDZ_P].rc_data;
+ ccount = rm->rm_col[c].rc_size / sizeof (src[0]);
+
+ if (c == rm->rm_firstdatacol) {
+ ASSERT(ccount == pcount);
+ for (i = 0; i < ccount; i++, src++, p++) {
+ *p = *src;
+ }
+ } else {
+ ASSERT(ccount <= pcount);
+ for (i = 0; i < ccount; i++, src++, p++) {
+ *p ^= *src;
+ }
+ }
+ }
+}
+
+static void
+vdev_raidz_generate_parity_pq(raidz_map_t *rm)
+{
+ uint64_t *p, *q, *src, pcnt, ccnt, mask, i;
+ int c;
+
+ pcnt = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (src[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_data;
+ p = rm->rm_col[VDEV_RAIDZ_P].rc_data;
+ q = rm->rm_col[VDEV_RAIDZ_Q].rc_data;
+
+ ccnt = rm->rm_col[c].rc_size / sizeof (src[0]);
+
+ if (c == rm->rm_firstdatacol) {
+ ASSERT(ccnt == pcnt || ccnt == 0);
+ for (i = 0; i < ccnt; i++, src++, p++, q++) {
+ *p = *src;
+ *q = *src;
+ }
+ for (; i < pcnt; i++, src++, p++, q++) {
+ *p = 0;
+ *q = 0;
+ }
+ } else {
+ ASSERT(ccnt <= pcnt);
+
+ /*
+ * Apply the algorithm described above by multiplying
+ * the previous result and adding in the new value.
+ */
+ for (i = 0; i < ccnt; i++, src++, p++, q++) {
+ *p ^= *src;
+
+ VDEV_RAIDZ_64MUL_2(*q, mask);
+ *q ^= *src;
+ }
+
+ /*
+ * Treat short columns as though they are full of 0s.
+ * Note that there's therefore nothing needed for P.
+ */
+ for (; i < pcnt; i++, q++) {
+ VDEV_RAIDZ_64MUL_2(*q, mask);
+ }
+ }
+ }
+}
+
+static void
+vdev_raidz_generate_parity_pqr(raidz_map_t *rm)
+{
+ uint64_t *p, *q, *r, *src, pcnt, ccnt, mask, i;
+ int c;
+
+ pcnt = rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (src[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_data;
+ p = rm->rm_col[VDEV_RAIDZ_P].rc_data;
+ q = rm->rm_col[VDEV_RAIDZ_Q].rc_data;
+ r = rm->rm_col[VDEV_RAIDZ_R].rc_data;
+
+ ccnt = rm->rm_col[c].rc_size / sizeof (src[0]);
+
+ if (c == rm->rm_firstdatacol) {
+ ASSERT(ccnt == pcnt || ccnt == 0);
+ for (i = 0; i < ccnt; i++, src++, p++, q++, r++) {
+ *p = *src;
+ *q = *src;
+ *r = *src;
+ }
+ for (; i < pcnt; i++, src++, p++, q++, r++) {
+ *p = 0;
+ *q = 0;
+ *r = 0;
+ }
+ } else {
+ ASSERT(ccnt <= pcnt);
+
+ /*
+ * Apply the algorithm described above by multiplying
+ * the previous result and adding in the new value.
+ */
+ for (i = 0; i < ccnt; i++, src++, p++, q++, r++) {
+ *p ^= *src;
+
+ VDEV_RAIDZ_64MUL_2(*q, mask);
+ *q ^= *src;
+
+ VDEV_RAIDZ_64MUL_4(*r, mask);
+ *r ^= *src;
+ }
+
+ /*
+ * Treat short columns as though they are full of 0s.
+ * Note that there's therefore nothing needed for P.
+ */
+ for (; i < pcnt; i++, q++, r++) {
+ VDEV_RAIDZ_64MUL_2(*q, mask);
+ VDEV_RAIDZ_64MUL_4(*r, mask);
+ }
+ }
+ }
+}
+
+/*
+ * Generate RAID parity in the first virtual columns according to the number of
+ * parity columns available.
+ */
+static void
+vdev_raidz_generate_parity(raidz_map_t *rm)
+{
+ 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");
+ }
+}
+
+static int
+vdev_raidz_reconstruct_p(raidz_map_t *rm, int *tgts, int ntgts)
+{
+ uint64_t *dst, *src, xcount, ccount, count, i;
+ int x = tgts[0];
+ int c;
+
+ ASSERT(ntgts == 1);
+ ASSERT(x >= rm->rm_firstdatacol);
+ ASSERT(x < rm->rm_cols);
+
+ xcount = rm->rm_col[x].rc_size / sizeof (src[0]);
+ ASSERT(xcount <= rm->rm_col[VDEV_RAIDZ_P].rc_size / sizeof (src[0]));
+ ASSERT(xcount > 0);
+
+ src = rm->rm_col[VDEV_RAIDZ_P].rc_data;
+ dst = rm->rm_col[x].rc_data;
+ for (i = 0; i < xcount; i++, dst++, src++) {
+ *dst = *src;
+ }
+
+ for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
+ src = rm->rm_col[c].rc_data;
+ dst = rm->rm_col[x].rc_data;
+
+ if (c == x)
+ continue;
+
+ ccount = rm->rm_col[c].rc_size / sizeof (src[0]);
+ count = MIN(ccount, xcount);
+
+ for (i = 0; i < count; i++, dst++, src++) {
+ *dst ^= *src;
+ }
+ }
+
+ return (1 << VDEV_RAIDZ_P);
+}
+
+static int
+vdev_raidz_reconstruct_q(raidz_map_t *rm, int *tgts, int ntgts)
+{
+ uint64_t *dst, *src, xcount, ccount, count, mask, i;
+ uint8_t *b;
+ int x = tgts[0];
+ int c, j, exp;
+
+ ASSERT(ntgts == 1);
+
+ xcount = rm->rm_col[x].rc_size / sizeof (src[0]);
+ ASSERT(xcount <= rm->rm_col[VDEV_RAIDZ_Q].rc_size / sizeof (src[0]));
+
+ for (c = rm->rm_firstdatacol; c < rm->rm_cols; c++) {
+ src = rm->rm_col[c].rc_data;
+ dst = rm->rm_col[x].rc_data;
+
+ if (c == x)
+ ccount = 0;
+ else
+ ccount = rm->rm_col[c].rc_size / sizeof (src[0]);
+
+ count = MIN(ccount, xcount);
+
+ if (c == rm->rm_firstdatacol) {
+ for (i = 0; i < count; i++, dst++, src++) {
+ *dst = *src;
+ }
+ for (; i < xcount; i++, dst++) {
+ *dst = 0;
+ }
+
+ } else {
+ for (i = 0; i < count; i++, dst++, src++) {
+ VDEV_RAIDZ_64MUL_2(*dst, mask);
+ *dst ^= *src;
+ }
+
+ for (; i < xcount; i++, dst++) {
+ VDEV_RAIDZ_64MUL_2(*dst, mask);
+ }
+ }
+ }
+
+ src = rm->rm_col[VDEV_RAIDZ_Q].rc_data;
+ dst = rm->rm_col[x].rc_data;
+ exp = 255 - (rm->rm_cols - 1 - x);
+
+ for (i = 0; i < xcount; i++, dst++, src++) {
+ *dst ^= *src;
+ for (j = 0, b = (uint8_t *)dst; j < 8; j++, b++) {
+ *b = vdev_raidz_exp2(*b, exp);
+ }
+ }
+
+ 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, *xd, *yd, tmp, a, b, aexp, bexp;
+ void *pdata, *qdata;
+ uint64_t xsize, ysize, i;
+ int x = tgts[0];
+ int y = tgts[1];
+
+ 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_data;
+ qdata = rm->rm_col[VDEV_RAIDZ_Q].rc_data;
+ xsize = rm->rm_col[x].rc_size;
+ ysize = rm->rm_col[y].rc_size;
+
+ rm->rm_col[VDEV_RAIDZ_P].rc_data =
+ zio_buf_alloc(rm->rm_col[VDEV_RAIDZ_P].rc_size);
+ rm->rm_col[VDEV_RAIDZ_Q].rc_data =
+ zio_buf_alloc(rm->rm_col[VDEV_RAIDZ_Q].rc_size);
+ 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 = pdata;
+ q = qdata;
+ pxy = rm->rm_col[VDEV_RAIDZ_P].rc_data;
+ qxy = rm->rm_col[VDEV_RAIDZ_Q].rc_data;
+ xd = rm->rm_col[x].rc_data;
+ yd = rm->rm_col[y].rc_data;
+
+ /*
+ * We now have:
+ * Pxy = P + D_x + D_y
+ * Qxy = Q + 2^(ndevs - 1 - x) * D_x + 2^(ndevs - 1 - y) * D_y
+ *
+ * We can then solve for D_x:
+ * D_x = A * (P + Pxy) + B * (Q + Qxy)
+ * where
+ * A = 2^(x - y) * (2^(x - y) + 1)^-1
+ * B = 2^(ndevs - 1 - x) * (2^(x - y) + 1)^-1
+ *
+ * With D_x in hand, we can easily solve for D_y:
+ * D_y = P + Pxy + D_x
+ */
+
+ a = vdev_raidz_pow2[255 + x - y];
+ b = vdev_raidz_pow2[255 - (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)];
+
+ for (i = 0; i < xsize; i++, p++, q++, pxy++, qxy++, xd++, yd++) {
+ *xd = vdev_raidz_exp2(*p ^ *pxy, aexp) ^
+ vdev_raidz_exp2(*q ^ *qxy, bexp);
+
+ if (i < ysize)
+ *yd = *p ^ *pxy ^ *xd;
+ }
+
+ zio_buf_free(rm->rm_col[VDEV_RAIDZ_P].rc_data,
+ rm->rm_col[VDEV_RAIDZ_P].rc_size);
+ zio_buf_free(rm->rm_col[VDEV_RAIDZ_Q].rc_data,
+ rm->rm_col[VDEV_RAIDZ_Q].rc_size);
+
+ /*
+ * Restore the saved parity data.
+ */
+ rm->rm_col[VDEV_RAIDZ_P].rc_data = pdata;
+ rm->rm_col[VDEV_RAIDZ_Q].rc_data = 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++) {
+ ASSERT3U(rows[i][j], ==, 0);
+ }
+ 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 {
+ ASSERT3U(rows[i][j], ==, 0);
+ }
+ }
+ }
+}
+
+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];
+ uint64_t dcount[VDEV_RAIDZ_MAXPARITY];
+ uint8_t log, 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 = rm->rm_col[c].rc_data;
+ 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] = rm->rm_col[cc].rc_data;
+ 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;
+
+ int code = 0;
+
+
+ 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);
+
+ return (code);
+}
+
+static int
+vdev_raidz_reconstruct(raidz_map_t *rm, int *t, int nt)
+{
+ int tgts[VDEV_RAIDZ_MAXPARITY], *dt;
+ int ntgts;
+ int i, c;
+ 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];
+
+ /*
+ * See if we can use any of our optimized reconstruction routines.
+ */
+ if (!vdev_raidz_default_to_general) {
+ 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 *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 (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;
+ *ashift = MAX(*ashift, cvd->vdev_ashift);
+ }
+
+ *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 int
+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];
+ zio_nowait(zio_vdev_child_io(zio, NULL, cvd,
+ rc->rc_offset, rc->rc_data, 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));
+ }
+
+ return (ZIO_PIPELINE_CONTINUE);
+ }
+
+ 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 = 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 = 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_data, rc->rc_size,
+ zio->io_type, zio->io_priority, 0,
+ vdev_raidz_child_done, rc));
+ }
+ }
+
+ return (ZIO_PIPELINE_CONTINUE);
+}
+
+
+/*
+ * Report a checksum error for a child of a RAID-Z device.
+ */
+static void
+raidz_checksum_error(zio_t *zio, raidz_col_t *rc, void *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,
+ rc->rc_offset, rc->rc_size, rc->rc_data, 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;
+
+ 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)
+{
+ void *orig[VDEV_RAIDZ_MAXPARITY];
+ int c, ret = 0;
+ raidz_col_t *rc;
+
+ for (c = 0; c < rm->rm_firstdatacol; c++) {
+ rc = &rm->rm_col[c];
+ if (!rc->rc_tried || rc->rc_error != 0)
+ continue;
+ orig[c] = zio_buf_alloc(rc->rc_size);
+ bcopy(rc->rc_data, orig[c], 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 (bcmp(orig[c], rc->rc_data, rc->rc_size) != 0) {
+ raidz_checksum_error(zio, rc, orig[c]);
+ rc->rc_error = ECKSUM;
+ ret++;
+ }
+ zio_buf_free(orig[c], rc->rc_size);
+ }
+
+ return (ret);
+}
+
+/*
+ * Keep statistics on all the ways that we used parity to correct data.
+ */
+static uint64_t raidz_corrected[1 << VDEV_RAIDZ_MAXPARITY];
+
+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;
+ void *orig[VDEV_RAIDZ_MAXPARITY];
+ int tstore[VDEV_RAIDZ_MAXPARITY + 2];
+ int *tgts = &tstore[1];
+ int current, 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] = zio_buf_alloc(rm->rm_col[0].rc_size);
+
+ current = 0;
+ next = tgts[current];
+
+ while (current != n) {
+ tgts[current] = next;
+ current = 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];
+ bcopy(rc->rc_data, orig[i], 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) {
+ atomic_inc_64(&raidz_corrected[code]);
+
+ 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 = ECKSUM;
+ }
+
+ ret = code;
+ goto done;
+ }
+
+ /*
+ * Restore the original data.
+ */
+ for (i = 0; i < n; i++) {
+ c = tgts[i];
+ rc = &rm->rm_col[c];
+ bcopy(orig[i], rc->rc_data, rc->rc_size);
+ }
+
+ do {
+ /*
+ * Find the next valid column after the current
+ * position..
+ */
+ for (next = tgts[current] + 1;
+ next < rm->rm_cols &&
+ rm->rm_col[next].rc_error != 0; next++)
+ continue;
+
+ ASSERT(next <= tgts[current + 1]);
+
+ /*
+ * If that spot is available, we're done here.
+ */
+ if (next != tgts[current + 1])
+ break;
+
+ /*
+ * Otherwise, find the next valid column after
+ * the previous position.
+ */
+ for (c = tgts[current - 1] + 1;
+ rm->rm_col[c].rc_error != 0; c++)
+ continue;
+
+ tgts[current] = c;
+ current++;
+
+ } while (current != n);
+ }
+ }
+ n--;
+done:
+ for (i = 0; i < n; i++) {
+ zio_buf_free(orig[i], rm->rm_col[0].rc_size);
+ }
+
+ return (ret);
+}
+
+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;
+ 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) {
+ atomic_inc_64(&raidz_corrected[code]);
+
+ /*
+ * 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_data, 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 = ECKSUM;
+
+ if (!(zio->io_flags & ZIO_FLAG_SPECULATIVE)) {
+ for (c = 0; c < rm->rm_cols; c++) {
+ rc = &rm->rm_col[c];
+ if (rc->rc_error == 0) {
+ zio_bad_cksum_t zbc;
+ zbc.zbc_has_cksum = 0;
+ zbc.zbc_injected =
+ rm->rm_ecksuminjected;
+
+ zfs_ereport_start_checksum(
+ zio->io_spa,
+ vd->vdev_child[rc->rc_devidx],
+ 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_data, rc->rc_size,
+ ZIO_TYPE_WRITE, zio->io_priority,
+ 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);
+}
+
+vdev_ops_t vdev_raidz_ops = {
+ vdev_raidz_open,
+ vdev_raidz_close,
+ vdev_raidz_asize,
+ vdev_raidz_io_start,
+ vdev_raidz_io_done,
+ vdev_raidz_state_change,
+ NULL,
+ NULL,
+ VDEV_TYPE_RAIDZ, /* name of this vdev type */
+ B_FALSE /* not a leaf vdev */
+};