Implement read-modify-write calculation and extract it into a separate file

osd_rmw.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <stdint.h>
+#include "object_id.h"
+#include "osd_id.h"
+
+#ifndef MEM_ALIGNMENT
+#define MEM_ALIGNMENT 512
+#endif
+
+struct buf_len_t
+{
+    void *buf;
+    uint64_t len;
+};
+
+struct osd_read_stripe_t
+{
+    void *read_buf, *write_buf;
+    uint32_t req_start, req_end;
+    uint32_t read_start, read_end;
+    uint32_t write_start, write_end;
+    bool missing;
+};
+
+void split_stripes(uint64_t pg_minsize, uint32_t bs_block_size, uint32_t start, uint32_t len, osd_read_stripe_t *stripes);
+
+void reconstruct_stripe(osd_read_stripe_t *stripes, int pg_size, int role);
+
+int extend_missing_stripes(osd_read_stripe_t *stripes, osd_num_t *osd_set, int minsize, int size);
+
+void* alloc_read_buffer(osd_read_stripe_t *stripes, int read_pg_size, uint64_t add_size);
+
+void* calc_rmw_reads(void *write_buf, osd_read_stripe_t *stripes, uint64_t *osd_set, uint64_t pg_size, uint64_t pg_minsize, uint64_t pg_cursize);
+
+void calc_rmw_parity(osd_read_stripe_t *stripes, int pg_size);