微视linux 通用块层之bio

最新推荐文章于 2025-01-22 22:00:00 发布

原创最新推荐文章于 2025-01-22 22:00:00 发布 · 484 阅读

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本文详细解析了Linux内核中intmpage_readpages函数的实现原理，该函数负责处理页面读取请求，通过调用do_mpage_readpage进行生物（bio）提交和页面分配。文章展示了如何在读取过程中管理生物结构和页面列表，确保数据从块设备正确读入内存。

int mpage_readpages(struct address_space *mapping, struct list_head *pages,
				unsigned nr_pages, get_block_t get_block)
{
	for (page_idx = 0; page_idx < nr_pages; page_idx++){
		struct page *page = list_entry(pages->prev, struct page, lru);
		bio = do_mpage_readpage(bio, page,
					nr_pages - page_idx,
					&last_block_in_bio, &map_bh,
					&first_logical_block,
					get_block);
		=>static struct bio *
		do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
				sector_t *last_block_in_bio, struct buffer_head *map_bh,
				unsigned long *first_logical_block, get_block_t get_block)
		{
			if (bio && (*last_block_in_bio != blocks[0] - 1))
				bio = mpage_bio_submit(READ, bio);
				
		alloc_new:
			if (bio == NULL) {
				bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
						min_t(int, nr_pages, bio_get_nr_vecs(bdev)),
						GFP_KERNEL);
			}
			if (bio_add_page(bio, page, length, 0) < length) {
				bio = mpage_bio_submit(READ, bio);
				goto alloc_new;
			}
		}
	}
	if (bio)
		mpage_bio_submit(READ, bio);
	return 0;	
		
}

bio与bio_vec
https://blog.youkuaiyun.com/zhufengtianya/article/details/42145985

宋宝华：文件读写（BIO）波澜壮阔的一生
https://blog.youkuaiyun.com/juS3Ve/article/details/79890688