Re: [PATCH] block: set rq->cmd_flags with bio->opf instead of data->cmd_flags when bio is not Null

[John Garry]

On 28/01/2019 15:57, Christoph Hellwig wrote:
> On Mon, Jan 28, 2019 at 03:36:58PM +0000, John Garry wrote:
> > As I understood, the problem is the scenario of calling
> > blk_mq_make_request()->bio_integrity_prep() where we then allocate a bio
> > integrity payload in calling bio_integrity_alloc().
> >
> > In this case, bio_integrity_alloc() sets bio->bi_opf |= REQ_INTEGRITY, which
> > is no longer consistent with data.cmd_flags.
>
> I don't see how that could happen:
>
> static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
> {
> 	...
>
> 	if (!bio_integrity_prep(bio))
> 		return BLK_QC_T_NONE;
>
> 	...
>
> 	data.cmd_flags = bio->bi_opf;
>         rq = blk_mq_get_request(q, bio, &data);

Your code is different to mine, then I see that this has been fixed in 
5.0-rc3:

commit 7809167da5c86fd6bf309b33dee7a797e263342f
Author: Ming Lei <ming.lei@xxxxxxxxxx>
Date:   Wed Jan 16 19:08:15 2019 +0800

    block: don't lose track of REQ_INTEGRITY flag

    We need to pass bio->bi_opf after bio intergrity preparing, otherwise
    the flag of REQ_INTEGRITY may not be set on the allocated request, then
    breaks block integrity.

    Fixes: f9afca4d367b ("blk-mq: pass in request/bio flags to queue 
mapping")
    Cc: Hannes Reinecke <hare@xxxxxxxx>
    Cc: Keith Busch <keith.busch@xxxxxxxxx>
    Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
    Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>


Sorry for the noise,
John

> .