Re: [PATCH 01/27] block: bio: introduce 4 helpers for cleanup

[Ming Lei]

On Wed, Apr 6, 2016 at 8:18 AM, Kent Overstreet
<kent.overstreet@xxxxxxxxx> wrote:
> On Tue, Apr 05, 2016 at 07:56:46PM +0800, Ming Lei wrote:
>> Some drivers access bio->bi_vcnt and bio->bi_io_vec directly,
>> firstly it isn't a good practice, secondly it may cause trouble
>> for converting to multipage bvecs.
>
> "not good practice" is OO bullshit snake oil without more justification. We
> don't plaster accessors everywhere without an actual reason.
>
> How would it cause trouble with multipage bvecs?

Simply speaking, the current drivers may depend on .bi_vcnt for
computing how many page there are in one bio. After multipage bvecs,
it is not true any more. Isn't it a actual reason?


Thanks,
Ming Lei