Mainly copied from kernel code, with minor modification to follow the
new naming schema.
Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
---
raid56.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
raid56.h | 4 ++++
2 files changed, 67 insertions(+)
diff --git a/raid56.c b/raid56.c
index 8c79c45..599533e 100644
--- a/raid56.c
+++ b/raid56.c
@@ -28,6 +28,7 @@
#include "disk-io.h"
#include "volumes.h"
#include "utils.h"
+#include "raid56.h"
/*
* This is the C data type to use
@@ -170,3 +171,65 @@ int raid5_gen_result(int nr_devs, size_t stripe_len, int
dest, void **data)
}
return 0;
}
+
+int raid6_recov_data2(int nr_devs, size_t stripe_len, int dest1, int dest2,
+ void **data)
+{
+ u8 *p, *q, *dp, *dq;
+ u8 px, qx, db;
+ const u8 *pbmul; /* P multiplier table for B data */
+ const u8 *qmul; /* Q multiplier table (for both) */
+ char *zero_mem1, *zero_mem2;
+ int ret = 0;
+
+ /* Early check */
+ if (dest1 < 0 || dest1 >= nr_devs - 2 ||
+ dest2 < 0 || dest2 >= nr_devs - 2 || dest1 >= dest2)
+ return -EINVAL;
+
+ zero_mem1 = calloc(1, stripe_len);
+ zero_mem2 = calloc(1, stripe_len);
+ if (!zero_mem1 || !zero_mem2) {
+ free(zero_mem1);
+ free(zero_mem2);
+ return -ENOMEM;
+ }
+
+ p = (u8 *)data[nr_devs - 2];
+ q = (u8 *)data[nr_devs - 1];
+
+ /* Compute syndrome with zero for the missing data pages
+ Use the dead data pages as temporary storage for
+ delta p and delta q */
+ dp = (u8 *)data[dest1];
+ data[dest1] = (void *)zero_mem1;
+ data[nr_devs - 2] = dp;
+ dq = (u8 *)data[dest2];
+ data[dest2] = (void *)zero_mem2;
+ data[nr_devs - 1] = dq;
+
+ raid6_gen_syndrome(nr_devs, stripe_len, data);
+
+ /* Restore pointer table */
+ data[dest1] = dp;
+ data[dest2] = dq;
+ data[nr_devs - 2] = p;
+ data[nr_devs - 1] = q;
+
+ /* Now, pick the proper data tables */
+ pbmul = raid6_gfmul[raid6_gfexi[dest2 - dest1]];
+ qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[dest1]^raid6_gfexp[dest2]]];
+
+ /* Now do it... */
+ while ( stripe_len-- ) {
+ px = *p ^ *dp;
+ qx = qmul[*q ^ *dq];
+ *dq++ = db = pbmul[px] ^ qx; /* Reconstructed B */
+ *dp++ = db ^ px; /* Reconstructed A */
+ p++; q++;
+ }
+
+ free(zero_mem1);
+ free(zero_mem2);
+ return ret;
+}
diff --git a/raid56.h b/raid56.h
index a05c14b..46fd3a9 100644
--- a/raid56.h
+++ b/raid56.h
@@ -19,6 +19,10 @@
void raid6_gen_syndrome(int disks, size_t bytes, void **ptrs);
int raid5_gen_result(int nr_devs, size_t stripe_len, int dest, void **data);
+/* Recover 2 data */
+int raid6_recov_data2(int nr_devs, size_t stripe_len, int dest1, int dest2,
+ void **data);
+
/* Galois field tables */
extern const u8 raid6_gfmul[256][256] __attribute__((aligned(256)));
extern const u8 raid6_vgfmul[256][32] __attribute__((aligned(256)));
--
2.10.1
--
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