On August 27, 2016 11:51:04 PM PDT, liuzhengyuan@xxxxxxxxxx wrote:
>From: ZhengYuan Liu <liuzhengyuan@xxxxxxxxxx>
>
>To test and choose the best algorithm for raid6, disks number
>and disks data must be offered. These input depend on page
>size and gfmul table at current time. It would cause the disk
>number less than 4 when the page size is more than 64KB.This
>patch would support arbitrarily page size by defining a macro
>for disks number and using a PRNG based on linear congruential
>bit to fill the disks data.
>
>Signed-off-by: ZhengYuan Liu <liuzhengyuan@xxxxxxxxxx>
>---
> lib/raid6/algos.c | 39 +++++++++++++++++++++++++--------------
> 1 file changed, 25 insertions(+), 14 deletions(-)
>
>diff --git a/lib/raid6/algos.c b/lib/raid6/algos.c
>index 975c6e0..3991ac6 100644
>--- a/lib/raid6/algos.c
>+++ b/lib/raid6/algos.c
>@@ -30,6 +30,8 @@ EXPORT_SYMBOL(raid6_empty_zero_page);
> #endif
> #endif
>
>+#define RAID6_DISKS 8
>+
> struct raid6_calls raid6_call;
> EXPORT_SYMBOL_GPL(raid6_call);
>
>@@ -129,7 +131,7 @@ static inline const struct raid6_recov_calls
>*raid6_choose_recov(void)
> }
>
> static inline const struct raid6_calls *raid6_choose_gen(
>- void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
>+ void *(*const dptrs)[RAID6_DISKS], const int disks)
> {
> unsigned long perf, bestgenperf, bestxorperf, j0, j1;
> int start = (disks>>1)-1, stop = disks-3; /* work on the second half
>of the disks */
>@@ -206,27 +208,36 @@ static inline const struct raid6_calls
>*raid6_choose_gen(
>
> int __init raid6_select_algo(void)
> {
>- const int disks = (65536/PAGE_SIZE)+2;
>+ const int disks = RAID6_DISKS;
>
> const struct raid6_calls *gen_best;
> const struct raid6_recov_calls *rec_best;
>- char *syndromes;
>- void *dptrs[(65536/PAGE_SIZE)+2];
>- int i;
>-
>- for (i = 0; i < disks-2; i++)
>- dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
>+ char *disk_ptr;
>+ void *dptrs[RAID6_DISKS];
>+ int32_t seed;
>+ int i, j;
>
>- /* Normal code - use a 2-page allocation to avoid D$ conflict */
>- syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
>+ /* use a 8-page allocation, The first 6 pages for disks
>+ and the last 2 pages for syndromes */
>+ disk_ptr = (void *) __get_free_pages(GFP_KERNEL, 3);
>
>- if (!syndromes) {
>+ if (!disk_ptr) {
> pr_err("raid6: Yikes! No memory available.\n");
> return -ENOMEM;
> }
>
>- dptrs[disks-2] = syndromes;
>- dptrs[disks-1] = syndromes + PAGE_SIZE;
>+ /*use a PRNG based on LCB to fill the disks*/
>+ seed = 1;
>+ for (i = 0; i < disks-2; i++) {
>+ dptrs[i] = disk_ptr + PAGE_SIZE*i;
>+ for (j = 0; j < PAGE_SIZE; j = j + 4) {
>+ seed = ((seed * 1103515245) + 12345) & 0x7fffffff;
>+ *(int32_t *)(dptrs[i]+j) = seed;
>+ }
>+ }
>+
>+ dptrs[disks-2] = disk_ptr + PAGE_SIZE*(disks-2);
>+ dptrs[disks-1] = disk_ptr + PAGE_SIZE*(disks-1);
>
> /* select raid gen_syndrome function */
> gen_best = raid6_choose_gen(&dptrs, disks);
>@@ -234,7 +245,7 @@ int __init raid6_select_algo(void)
> /* select raid recover functions */
> rec_best = raid6_choose_recov();
>
>- free_pages((unsigned long)syndromes, 1);
>+ free_pages((unsigned long)disk_ptr, 3);
>
> return gen_best && rec_best ? 0 : -EINVAL;
> }
Linear congruential exactly what we don't want...
--
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