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, 171 insertions, 0 deletions

diff --git a/lib/raid6/raid6algos.c b/lib/raid6/raid6algos.c
new file mode 100644
index 000000000000..866215ac7f25
--- /dev/null
+++ b/lib/raid6/raid6algos.c
@@ -0,0 +1,171 @@
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ *   Copyright 2002 H. Peter Anvin - All Rights Reserved
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
+ *   Boston MA 02111-1307, USA; either version 2 of the License, or
+ *   (at your option) any later version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * raid6algos.c
+ *
+ * Algorithm list and algorithm selection for RAID-6
+ */
+
+#include <linux/raid/pq.h>
+#ifndef __KERNEL__
+#include <sys/mman.h>
+#include <stdio.h>
+#else
+#if !RAID6_USE_EMPTY_ZERO_PAGE
+/* In .bss so it's zeroed */
+const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
+EXPORT_SYMBOL(raid6_empty_zero_page);
+#endif
+#endif
+
+struct raid6_calls raid6_call;
+EXPORT_SYMBOL_GPL(raid6_call);
+
+/* Various routine sets */
+extern const struct raid6_calls raid6_intx1;
+extern const struct raid6_calls raid6_intx2;
+extern const struct raid6_calls raid6_intx4;
+extern const struct raid6_calls raid6_intx8;
+extern const struct raid6_calls raid6_intx16;
+extern const struct raid6_calls raid6_intx32;
+extern const struct raid6_calls raid6_mmxx1;
+extern const struct raid6_calls raid6_mmxx2;
+extern const struct raid6_calls raid6_sse1x1;
+extern const struct raid6_calls raid6_sse1x2;
+extern const struct raid6_calls raid6_sse2x1;
+extern const struct raid6_calls raid6_sse2x2;
+extern const struct raid6_calls raid6_sse2x4;
+extern const struct raid6_calls raid6_altivec1;
+extern const struct raid6_calls raid6_altivec2;
+extern const struct raid6_calls raid6_altivec4;
+extern const struct raid6_calls raid6_altivec8;
+
+const struct raid6_calls * const raid6_algos[] = {
+        &raid6_intx1,
+        &raid6_intx2,
+        &raid6_intx4,
+        &raid6_intx8,
+#if defined(__ia64__)
+        &raid6_intx16,
+        &raid6_intx32,
+#endif
+#if defined(__i386__) && !defined(__arch_um__)
+        &raid6_mmxx1,
+        &raid6_mmxx2,
+        &raid6_sse1x1,
+        &raid6_sse1x2,
+        &raid6_sse2x1,
+        &raid6_sse2x2,
+#endif
+#if defined(__x86_64__) && !defined(__arch_um__)
+        &raid6_sse2x1,
+        &raid6_sse2x2,
+        &raid6_sse2x4,
+#endif
+#ifdef CONFIG_ALTIVEC
+        &raid6_altivec1,
+        &raid6_altivec2,
+        &raid6_altivec4,
+        &raid6_altivec8,
+#endif
+        NULL
+};
+
+#ifdef __KERNEL__
+#define RAID6_TIME_JIFFIES_LG2  4
+#else
+/* Need more time to be stable in userspace */
+#define RAID6_TIME_JIFFIES_LG2  9
+#define time_before(x, y) ((x) < (y))
+#endif
+
+/* Try to pick the best algorithm */
+/* This code uses the gfmul table as convenient data set to abuse */
+
+int __init raid6_select_algo(void)
+{
+        const struct raid6_calls * const * algo;
+        const struct raid6_calls * best;
+        char *syndromes;
+        void *dptrs[(65536/PAGE_SIZE)+2];
+        int i, disks;
+        unsigned long perf, bestperf;
+        int bestprefer;
+        unsigned long j0, j1;
+
+        disks = (65536/PAGE_SIZE)+2;
+        for ( i = 0 ; i < disks-2 ; i++ ) {
+                dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
+        }
+
+        /* Normal code - use a 2-page allocation to avoid D$ conflict */
+        syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
+
+        if ( !syndromes ) {
+                printk("raid6: Yikes!  No memory available.\n");
+                return -ENOMEM;
+        }
+
+        dptrs[disks-2] = syndromes;
+        dptrs[disks-1] = syndromes + PAGE_SIZE;
+
+        bestperf = 0;  bestprefer = 0;  best = NULL;
+
+        for ( algo = raid6_algos ; *algo ; algo++ ) {
+                if ( !(*algo)->valid || (*algo)->valid() ) {
+                        perf = 0;
+
+                        preempt_disable();
+                        j0 = jiffies;
+                        while ( (j1 = jiffies) == j0 )
+                                cpu_relax();
+                        while (time_before(jiffies,
+                                            j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
+                                (*algo)->gen_syndrome(disks, PAGE_SIZE, dptrs);
+                                perf++;
+                        }
+                        preempt_enable();
+
+                        if ( (*algo)->prefer > bestprefer ||
+                             ((*algo)->prefer == bestprefer &&
+                              perf > bestperf) ) {
+                                best = *algo;
+                                bestprefer = best->prefer;
+                                bestperf = perf;
+                        }
+                        printk("raid6: %-8s %5ld MB/s\n", (*algo)->name,
+                               (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
+                }
+        }
+
+        if (best) {
+                printk("raid6: using algorithm %s (%ld MB/s)\n",
+                       best->name,
+                       (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
+                raid6_call = *best;
+        } else
+                printk("raid6: Yikes!  No algorithm found!\n");
+
+        free_pages((unsigned long)syndromes, 1);
+
+        return best ? 0 : -EINVAL;
+}
+
+static void raid6_exit(void)
+{
+        do { } while (0);
+}
+
+subsys_initcall(raid6_select_algo);
+module_exit(raid6_exit);
+MODULE_LICENSE("GPL");