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;
+}