Re: [PATCHv5 0/4] block integrity: directly map user space addresses

[Keith Busch <kbusch@kernel.org>]

On Fri, Dec 01, 2023 at 04:13:45PM +0530, Kanchan Joshi wrote:
> On 12/1/2023 3:23 AM, Keith Busch wrote:
> > From: Keith Busch<kbusch@kernel.org>
> 
> This causes a regression (existed in previous version too).
> System freeze on issuing single read/write io that used to work fine 
> earlier:
> fio -iodepth=1 -rw=randread -ioengine=io_uring_cmd -cmd_type=nvme 
> -bs=4096 -numjobs=1 -size=4096 -filename=/dev/ng0n1 -md_per_io_size=8 
> -name=pt
> 
> This is because we pin one bvec during submission, but unpin 4 on 
> completion. bio_integrity_unpin_bvec() uses bip->bip_max_vcnt, which is 
> set to 4 (equal to BIO_INLINE_VECS) in this case.
> 
> To use bip_max_vcnt the way this series uses, we need below patch/fix:

Thanks for the catch! Earlier versions of this series was capped by the
byte count rather than the max_vcnt value, so the inline condition
didn't matter before. I think your update looks good. I'll double check
what's going on with my custom tests to see why it didn't see this
problem.
 
> diff --git a/block/bio-integrity.c b/block/bio-integrity.c
> index 674a2c80454b..feef615e2c9c 100644
> --- a/block/bio-integrity.c
> +++ b/block/bio-integrity.c
> @@ -69,15 +69,15 @@ struct bio_integrity_payload 
> *bio_integrity_alloc(struct bio *bio,
> 
>          memset(bip, 0, sizeof(*bip));
> 
> +       /* always report as many vecs as asked explicitly, not inline 
> vecs */
> +       bip->bip_max_vcnt = nr_vecs;
>          if (nr_vecs > inline_vecs) {
> -               bip->bip_max_vcnt = nr_vecs;
>                  bip->bip_vec = bvec_alloc(&bs->bvec_integrity_pool,
>                                            &bip->bip_max_vcnt, gfp_mask);
>                  if (!bip->bip_vec)
>                          goto err;
>          } else {
>                  bip->bip_vec = bip->bip_inline_vecs;
> -               bip->bip_max_vcnt = inline_vecs;
>          }
> 
>          bip->bip_bio = bio;