md: Factor out RAID6 algorithms into lib/

We'll want to use these in btrfs too.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 124 insertions, 0 deletions

diff --git a/lib/raid6/raid6test/test.c b/lib/raid6/raid6test/test.c
new file mode 100644
index 000000000000..7a930318b17d
--- /dev/null
+++ b/lib/raid6/raid6test/test.c
@@ -0,0 +1,124 @@
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ *   Copyright 2002-2007 H. Peter Anvin - All Rights Reserved
+ *
+ *   This file is part of the Linux kernel, and is made available under
+ *   the terms of the GNU General Public License version 2 or (at your
+ *   option) any later version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * raid6test.c
+ *
+ * Test RAID-6 recovery with various algorithms
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <linux/raid/pq.h>
+
+#define NDISKS          16      /* Including P and Q */
+
+const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
+struct raid6_calls raid6_call;
+
+char *dataptrs[NDISKS];
+char data[NDISKS][PAGE_SIZE];
+char recovi[PAGE_SIZE], recovj[PAGE_SIZE];
+
+static void makedata(void)
+{
+        int i, j;
+
+        for (i = 0; i < NDISKS; i++) {
+                for (j = 0; j < PAGE_SIZE; j++)
+                        data[i][j] = rand();
+
+                dataptrs[i] = data[i];
+        }
+}
+
+static char disk_type(int d)
+{
+        switch (d) {
+        case NDISKS-2:
+                return 'P';
+        case NDISKS-1:
+                return 'Q';
+        default:
+                return 'D';
+        }
+}
+
+static int test_disks(int i, int j)
+{
+        int erra, errb;
+
+        memset(recovi, 0xf0, PAGE_SIZE);
+        memset(recovj, 0xba, PAGE_SIZE);
+
+        dataptrs[i] = recovi;
+        dataptrs[j] = recovj;
+
+        raid6_dual_recov(NDISKS, PAGE_SIZE, i, j, (void **)&dataptrs);
+
+        erra = memcmp(data[i], recovi, PAGE_SIZE);
+        errb = memcmp(data[j], recovj, PAGE_SIZE);
+
+        if (i < NDISKS-2 && j == NDISKS-1) {
+                /* We don't implement the DQ failure scenario, since it's
+                   equivalent to a RAID-5 failure (XOR, then recompute Q) */
+                erra = errb = 0;
+        } else {
+                printf("algo=%-8s  faila=%3d(%c)  failb=%3d(%c)  %s\n",
+                       raid6_call.name,
+                       i, disk_type(i),
+                       j, disk_type(j),
+                       (!erra && !errb) ? "OK" :
+                       !erra ? "ERRB" :
+                       !errb ? "ERRA" : "ERRAB");
+        }
+
+        dataptrs[i] = data[i];
+        dataptrs[j] = data[j];
+
+        return erra || errb;
+}
+
+int main(int argc, char *argv[])
+{
+        const struct raid6_calls *const *algo;
+        int i, j;
+        int err = 0;
+
+        makedata();
+
+        for (algo = raid6_algos; *algo; algo++) {
+                if (!(*algo)->valid || (*algo)->valid()) {
+                        raid6_call = **algo;
+
+                        /* Nuke syndromes */
+                        memset(data[NDISKS-2], 0xee, 2*PAGE_SIZE);
+
+                        /* Generate assumed good syndrome */
+                        raid6_call.gen_syndrome(NDISKS, PAGE_SIZE,
+                                                (void **)&dataptrs);
+
+                        for (i = 0; i < NDISKS-1; i++)
+                                for (j = i+1; j < NDISKS; j++)
+                                        err += test_disks(i, j);
+                }
+                printf("\n");
+        }
+
+        printf("\n");
+        /* Pick the best algorithm test */
+        raid6_select_algo();
+
+        if (err)
+                printf("\n*** ERRORS FOUND ***\n");
+
+        return err;
+}