return sg_copy_buffer(sgl, nents, buf, buflen, 1);
}
EXPORT_SYMBOL(sg_copy_to_buffer);
+
+/*
+ * Can switch to the next dst_sg element, so, to copy to strictly only
+ * one dst_sg element, it must be either last in the chain, or
+ * copy_len == dst_sg->length.
+ */
+static int sg_copy_elem(struct scatterlist **pdst_sg, size_t *pdst_len,
+ size_t *pdst_offs, struct scatterlist *src_sg,
+ size_t copy_len,
+ enum km_type d_km_type, enum km_type s_km_type)
+{
+ int res = 0;
+ struct scatterlist *dst_sg;
+ size_t src_len, dst_len, src_offs, dst_offs;
+ struct page *src_page, *dst_page;
+
+ dst_sg = *pdst_sg;
+ dst_len = *pdst_len;
+ dst_offs = *pdst_offs;
+ dst_page = sg_page(dst_sg);
+
+ src_page = sg_page(src_sg);
+ src_len = src_sg->length;
+ src_offs = src_sg->offset;
+
+ do {
+ void *saddr, *daddr;
+ size_t n;
+
+ saddr = kmap_atomic(src_page +
+ (src_offs >> PAGE_SHIFT), s_km_type) +
+ (src_offs & ~PAGE_MASK);
+ daddr = kmap_atomic(dst_page +
+ (dst_offs >> PAGE_SHIFT), d_km_type) +
+ (dst_offs & ~PAGE_MASK);
+
+ if (((src_offs & ~PAGE_MASK) == 0) &&
+ ((dst_offs & ~PAGE_MASK) == 0) &&
+ (src_len >= PAGE_SIZE) && (dst_len >= PAGE_SIZE) &&
+ (copy_len >= PAGE_SIZE)) {
+ copy_page(daddr, saddr);
+ n = PAGE_SIZE;
+ } else {
+ n = min_t(size_t, PAGE_SIZE - (dst_offs & ~PAGE_MASK),
+ PAGE_SIZE - (src_offs & ~PAGE_MASK));
+ n = min(n, src_len);
+ n = min(n, dst_len);
+ n = min_t(size_t, n, copy_len);
+ memcpy(daddr, saddr, n);
+ }
+ dst_offs += n;
+ src_offs += n;
+
+ kunmap_atomic(saddr, s_km_type);
+ kunmap_atomic(daddr, d_km_type);
+
+ res += n;
+ copy_len -= n;
+ if (copy_len == 0)
+ goto out;
+
+ src_len -= n;
+ dst_len -= n;
+ if (dst_len == 0) {
+ dst_sg = sg_next(dst_sg);
+ if (dst_sg == NULL)
+ goto out;
+ dst_page = sg_page(dst_sg);
+ dst_len = dst_sg->length;
+ dst_offs = dst_sg->offset;
+ }
+ } while (src_len > 0);
+
+out:
+ *pdst_sg = dst_sg;
+ *pdst_len = dst_len;
+ *pdst_offs = dst_offs;
+ return res;
+}
+
+/**
+ * sg_copy - copy one SG vector to another
+ * @dst_sg: destination SG
+ * @src_sg: source SG
+ * @nents_to_copy: maximum number of entries to copy
+ * @copy_len: maximum amount of data to copy. If 0, then copy all.
+ * @d_km_type: kmap_atomic type for the destination SG
+ * @s_km_type: kmap_atomic type for the source SG
+ *
+ * Description:
+ * Data from the source SG vector will be copied to the destination SG
+ * vector. End of the vectors will be determined by sg_next() returning
+ * NULL. Returns number of bytes copied.
+ */
+int sg_copy(struct scatterlist *dst_sg, struct scatterlist *src_sg,
+ int nents_to_copy, size_t copy_len,
+ enum km_type d_km_type, enum km_type s_km_type)
+{
+ int res = 0;
+ size_t dst_len, dst_offs;
+
+ if (copy_len == 0)
+ copy_len = 0x7FFFFFFF; /* copy all */
+
+ if (nents_to_copy == 0)
+ nents_to_copy = 0x7FFFFFFF; /* copy all */
+
+ dst_len = dst_sg->length;
+ dst_offs = dst_sg->offset;
+
+ do {
+ int copied = sg_copy_elem(&dst_sg, &dst_len, &dst_offs,
+ src_sg, copy_len, d_km_type, s_km_type);
+ copy_len -= copied;
+ res += copied;
+ if ((copy_len == 0) || (dst_sg == NULL))
+ goto out;
+
+ nents_to_copy--;
+ if (nents_to_copy == 0)
+ goto out;
+
+ src_sg = sg_next(src_sg);
+ } while (src_sg != NULL);
+
+out:
+ return res;
+}
+EXPORT_SYMBOL(sg_copy);