[RFC PATCH 1/2] block: change rq_integrity_vec to respect the iterator

[Ming Lei]

On Wed, May 15, 2024 at 03:28:11PM +0200, Mikulas Patocka wrote:
> If we allocate a bio that is larger than NVMe maximum request size, attach
> integrity metadata to it and send it to the NVMe subsystem, the integrity
> metadata will be corrupted.
> 
> Splitting the bio works correctly. The function bio_split will clone the
> bio, trim the iterator of the first bio and advance the iterator of the
> second bio.
> 
> However, the function rq_integrity_vec has a bug - it returns the first
> vector of the bio's metadata and completely disregards the metadata
> iterator that was advanced when the bio was split. Thus, the second bio
> uses the same metadata as the first bio and this leads to metadata
> corruption.

Wrt. NVMe, inside blk_mq_submit_bio(), bio_integrity_prep() is called after
bio is split, ->bi_integrity is actually allocated for every split bio, so I
am not sure if the issue is related with bio splitting. Or is it related
with DM over NVMe?

However, rq_integrity_vec() may not work correctly in case of bio merge.


Thanks, 
Ming