static void

raid0_submit_rw_request(struct raid_bdev_io *raid_io)   （原版代码）

{

......

 

    start_strip = bdev_io->u.bdev.offset_blocks >> raid_bdev->strip_size_shift;

    end_strip = (bdev_io->u.bdev.offset_blocks + bdev_io->u.bdev.num_blocks - 1) >>

            raid_bdev->strip_size_shift;  

    if (start_strip != end_strip && raid_bdev->num_base_bdevs > 1) {

        return;

    }

 

    pd_strip = start_strip / raid_bdev->num_base_bdevs;

    pd_idx = start_strip % raid_bdev->num_base_bdevs;

    offset_in_strip = bdev_io->u.bdev.offset_blocks & (raid_bdev->strip_size - 1);

    pd_lba = (pd_strip << raid_bdev->strip_size_shift) + offset_in_strip;

    pd_blocks = bdev_io->u.bdev.num_blocks;

    base_info = &raid_bdev->base_bdev_info[pd_idx];

    base_ch = raid_ch->base_channel[pd_idx];

    if (bdev_io->type == SPDK_BDEV_IO_TYPE_WRITE) {

        ret = spdk_bdev_writev_blocks_ext(base_info->desc, base_ch,

                          bdev_io->u.bdev.iovs, bdev_io->u.bdev.iovcnt,

                          pd_lba, pd_blocks, raid0_bdev_io_completion,

                          raid_io, bdev_io->u.bdev.ext_opts);

    }

 

......

}

 

在raid0 write blocks前加入打印，4个base bdev组合成了一个raid0，写入1M的数据，一个block是4k，一个io的num_blocks是16，也就是一次写入64k。得到log如下（两行为一个io，比如offect_blocks所在的行和pd_strip所在的行一共两行组成了一个io）：

条带的个数范围是0~15，一共16个条带，一个条带64k（不满64k的为实际大小），一共写了1M的数据下去。offset_blocks是数据的逻辑地址，pd_idx是base bdev的id,  pd_strip是一个base bdev内按64k划分后的block编号。第一个64k先写第0个base bdev的第0个block，第二个64k写第1个base bdev的第0个block....

 

得到条带写的方式如下：