Initial commit

Signed-off-by: Robert Baldyga <robert.baldyga@intel.com>

modules/cas_cache/utils/utils_data.c

@@ -0,0 +1,130 @@
+/*
+* Copyright(c) 2012-2019 Intel Corporation
+* SPDX-License-Identifier: BSD-3-Clause-Clear
+*/
+
+#include "cas_cache.h"
+
+/**
+ * This function locates index of IO vec from given vecs array where byte at
+ * offset is located. When found it returns its index and byte offset within
+ * this vec.
+ * @param vecs IO vector array to be searched
+ * @param vec_num number of items in IO vector array
+ * @param offset byte offset to be found
+ * @param offset_in_vec byte offset within found IO vec
+ * @return vec index if it lies within specified buffer, otherwise -1
+ */
+static int get_starting_vec(struct bio_vec *vecs, uint64_t vecs_num,
+		uint64_t offset, uint64_t *offset_in_vec)
+{
+	int i;
+
+	for (i = 0; i < vecs_num; i++) {
+		if (vecs[i].bv_len > offset) {
+			if (offset_in_vec != NULL)
+				*offset_in_vec = offset;
+			return i;
+		}
+		offset -= vecs[i].bv_len;
+	}
+
+	return -1;
+}
+
+uint64_t cas_data_cpy(struct bio_vec *dst, uint64_t dst_num,
+		struct bio_vec *src, uint64_t src_num,
+		uint64_t to, uint64_t from, uint64_t bytes)
+{
+	uint64_t i, j, dst_len, src_len, to_copy;
+	uint64_t dst_off, src_off;
+	uint64_t written = 0;
+	int ret;
+	void *dst_p, *src_p;
+	struct bio_vec *curr_dst, *curr_src;
+
+	/* Locate vec idx and offset in dst vec array */
+	ret = get_starting_vec(dst, dst_num, to, &to);
+	if (ret < 0) {
+		CAS_PRINT_RL(KERN_INFO "llu dst buffer too small "
+				"to_offset=%llu bytes=%llu", to, bytes);
+		return 0;
+	}
+	j = ret;
+
+	/* Locate vec idx and offset in src vec array */
+	ret = get_starting_vec(src, src_num, from, &from);
+	if (ret < 0) {
+		CAS_PRINT_RL(KERN_INFO "llu src buffer too small "
+				"from_offset=%llu bytes=%llu", from, bytes);
+		return 0;
+	}
+	i = ret;
+
+	curr_dst = &dst[j];
+	curr_src = &src[i];
+
+	dst_off = curr_dst->bv_offset + to;
+	dst_len = curr_dst->bv_len - to;
+
+	src_off = curr_src->bv_offset + from;
+	src_len = curr_src->bv_len - from;
+
+	while (written < bytes) {
+		dst_p = page_address(curr_dst->bv_page) + dst_off;
+		src_p = page_address(curr_src->bv_page) + src_off;
+
+		to_copy = src_len > dst_len ? dst_len : src_len;
+
+		/* Prevent from copying too much*/
+		if ((written + to_copy) > bytes)
+			to_copy = bytes - written;
+
+		memcpy(dst_p, src_p, to_copy);
+		written += to_copy;
+
+		if (written == bytes)
+			break;
+
+		/* Setup new len and offset. */
+		dst_off += to_copy;
+		dst_len -= to_copy;
+
+		src_off += to_copy;
+		src_len -= to_copy;
+
+		/* Go to next src buffer */
+		if (src_len == 0) {
+			i++;
+
+			/* Setup new len and offset. */
+			if (i < src_num) {
+				curr_src = &src[i];
+				src_off = curr_src->bv_offset;
+				src_len = curr_src->bv_len;
+			} else {
+				break;
+			}
+		}
+
+		/* Go to next dst buffer */
+		if (dst_len == 0) {
+			j++;
+
+			if (j < dst_num) {
+				curr_dst = &dst[j];
+				dst_off = curr_dst->bv_offset;
+				dst_len = curr_dst->bv_len;
+			} else {
+				break;
+			}
+		}
+	}
+
+	if (written != bytes) {
+		CAS_PRINT_RL(KERN_INFO "Written bytes not equal requested bytes "
+			"(written=%llu; requested=%llu)", written, bytes);
+	}
+
+	return written;
+}