如何将数据缓冲区 (bio_vec-s) 从原始 BIO 克隆到新的 bio_vec 集？

Question

我需要克隆数据，bi_io_vec中的生物已经携带了这些数据。我正在寻找执行调用的正确顺序：

新bio_vec分配
复制原来的bio_vec-s到新的
取消分配 bio_vec-s 区域

Answer 1

static int __dua_bvec_clone (
        struct bio  *src,
        IOB_ARGS    *iob_args
            )
{
int status;
unsigned nr_vecs = src->bi_vcnt;
struct bio *dst;
struct bvec_iter src_iter, dst_iter;
struct bio_vec  src_bv, dst_bv;
void *src_p, *dst_p;
unsigned bv_len;

    $TRACE("Start cloning ...");

    $SHOW_PTR(src);
    $SHOW_INT(src->bi_vcnt);

    /* Allocate a memory for a new 'bio' structure */
    if ( !(dst = bio_clone_bioset(src, GFP_KERNEL, src->bi_pool /*NULL*/)) )
        {
        printk(KERN_ERR  __MODULE__ ": bio_clone_bioset() -> NULL\n");

        return  -ENOMEM;
        }

    if ( status = bio_alloc_pages(dst , GFP_KERNEL))
        {
        printk(KERN_ERR  __MODULE__ ": bio_alloc_pages() -> %d\n", status);

        return  status;
        }

    /* Copy data from source bio_vec-s to a new bio_vec-s set */
    src_iter = src->bi_iter;
    dst_iter = dst->bi_iter;

    while( nr_vecs--)
        {
        src_bv = bio_iter_iovec(src, src_iter);
        dst_bv = bio_iter_iovec(dst, dst_iter);

        bv_len = min(src_bv.bv_len, dst_bv.bv_len);

        src_p = kmap_atomic(src_bv.bv_page);
        dst_p = kmap_atomic(dst_bv.bv_page);

        $SHOW_PTR(src_p);
        $SHOW_PTR(dst_p);

        memcpy(dst_p + dst_bv.bv_offset, src_p + src_bv.bv_offset, bv_len);

        kunmap_atomic(dst_p);
        kunmap_atomic(src_p);

        bio_advance_iter(src, &src_iter, bv_len);
        bio_advance_iter(dst, &dst_iter, bv_len);
        }



    iob_args->bi_io_vec = src->bi_io_vec;
    src->bi_io_vec = dst->bi_io_vec;

    iob_args->bio = dst;

    $TRACE("Cloned.");

    return  0;
}

如何将数据缓冲区 (bio_vec-s) 从原始 BIO 克隆到新的 bio_vec 集？

How to cloning data buffers (bio_vec-s) from original BIO to a new bio_vec set?

linux-device-driver