Re: [PATCH] block: Make __bio_clone_fast() copy bi_vcnt

Bart Van Assche
2018-06-28T15:21:29Z

On 06/27/18 17:30, Ming Lei wrote:
> One core idea of immutable bvec is to use bio->bi_iter and the original
> bvec table to iterate over anywhere in the bio. That is why .bi_io_vec
> needs to copy, but not see any reason why .bi_vcnt needs to do.
>
> Do you have use cases on .bi_vcnt for cloned bio?

So far this is only a theoretical concern. There are many functions in
the block layer that use .bi_vcnt, and it is a lot of work to figure out
all the callers of all these functions.

Bart.