Introduce new function raid5_gen_result() to calculate parity or data
stripe.
Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
---
v2:
Patch split
Change parameter type from void* to char* for xor_range()
Change parameter order for xxor_range()
Handle unaligned memory address for xor_range()
---
disk-io.h | 1 +
raid56.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 64 insertions(+)
diff --git a/disk-io.h b/disk-io.h
index 440baa9..9fc7e92 100644
--- a/disk-io.h
+++ b/disk-io.h
@@ -192,5 +192,6 @@ int write_and_map_eb(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
/* raid56.c */
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);
#endif
diff --git a/raid56.c b/raid56.c
index 833df5f..8c79c45 100644
--- a/raid56.c
+++ b/raid56.c
@@ -26,6 +26,8 @@
#include "kerncompat.h"
#include "ctree.h"
#include "disk-io.h"
+#include "volumes.h"
+#include "utils.h"
/*
* This is the C data type to use
@@ -107,3 +109,64 @@ void raid6_gen_syndrome(int disks, size_t bytes, void
**ptrs)
}
}
+static void xor_range(char *dst, const char*src, size_t size)
+{
+ /* Move to DWORD aligned */
+ while (size && ((unsigned long)dst & sizeof(unsigned long))) {
+ *dst++ ^= *src++;
+ size--;
+ }
+
+ /* DWORD aligned part */
+ while (size >= sizeof(unsigned long)) {
+ *(unsigned long *)dst ^= *(unsigned long *)src;
+ src += sizeof(unsigned long);
+ dst += sizeof(unsigned long);
+ size -= sizeof(unsigned long);
+ }
+ /* Remaining */
+ while (size) {
+ *dst++ ^= *src++;
+ size--;
+ }
+}
+
+/*
+ * Generate desired data/parity stripe for RAID5
+ *
+ * @nr_devs: Total number of devices, including parity
+ * @stripe_len: Stripe length
+ * @data: Data, with special layout:
+ * data[0]: Data stripe 0
+ * data[nr_devs-2]: Last data stripe
+ * data[nr_devs-1]: RAID5 parity
+ * @dest: To generate which data. should follow above data layout
+ */
+int raid5_gen_result(int nr_devs, size_t stripe_len, int dest, void **data)
+{
+ int i;
+ char *buf = data[dest];
+
+ /* Validation check */
+ if (stripe_len <= 0 || stripe_len != BTRFS_STRIPE_LEN) {
+ error("invalid parameter for %s", __func__);
+ return -EINVAL;
+ }
+
+ if (dest >= nr_devs || nr_devs < 2) {
+ error("invalid parameter for %s", __func__);
+ return -EINVAL;
+ }
+ /* Shortcut for 2 devs RAID5, which is just RAID1 */
+ if (nr_devs == 2) {
+ memcpy(data[dest], data[1 - dest], stripe_len);
+ return 0;
+ }
+ memset(buf, 0, stripe_len);
+ for (i = 0; i < nr_devs; i++) {
+ if (i == dest)
+ continue;
+ xor_range(buf, data[i], stripe_len);
+ }
+ return 0;
+}
--
2.10.0
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