Reading disks sectors

[fser@code-libre.org (François)]

Hello,

I'm trying to read raw disks sectors using bio requests.
I found a sample in a stackoverflow answer which seems to do exactly
what I'm trying to : http://stackoverflow.com/a/17527300/51760
Reading this, a few questions came to me:


1/ The API is outdated, and bio struct no longer have bi_sector for instance.
Those fields are now in bvec_iter (see
http://lxr.free-electrons.com/source/include/linux/blk_types.h?v=3.19).

bio struct do have  bi_iter field, so I was wondering wether it's safe
to populate the bi_iter directly ie:

- bio->bi_sector = sector;
+ bio->bi_iter.bi_sector = sector;

2/ There is a generic bi_endio function in bio.c.
What should readComplete implement? IMO it should just complete the
"event" (of type struct completion), and then I can just call the
bio_endio function provided by bio.c. Is that correct?

Thanks in advance!

---
Fran?ois