Re: [PATCH v9 05/13] block: add dma-buf support for raw bdev

[Jens Axboe]

On 10/8/26 6:27 AM, Anuj Gupta/Anuj Gupta wrote:
> On 10/7/2026 7:12 AM, Pavel Begunkov wrote:
>> +static int blkdev_init_dma_buf_io_ctx(struct file *file,
>> +				      struct dma_buf_io_ctx *ctx)
>> +{
>> +	struct block_device *bdev = file_bdev(file);
>> +	struct gendisk *disk = bdev->bd_disk;
>> +
>> +	if (!(file->f_flags & O_DIRECT))
>> +		return -EINVAL;
>> +	if (!disk->fops->init_dma_buf_io_ctx)
>> +		return -EOPNOTSUPP;
> 
> dma-buf doesn't work with PI: bi_dmabuf_map aliases bi_io_vec, and 
> blk_integrity_iterate() walks it as bvecs to generate/verify the 
> checksum. rw-dmabuf liburing test hangs on a PI enabled NVMe. Something 
> like below is needed:
> 
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index e929f94b25c7..1b7f8cbbda8b 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -3150,6 +3150,12 @@ void blk_mq_submit_bio(struct bio *bio)
>                  goto queue_exit;
>          }
> 
> +       if (unlikely(op_is_dmabuf(bio->bi_opf) &&
> +               bdev_has_integrity_csum(bio->bi_bdev))) {
> +               bio_endio_status(bio, BLK_STS_NOTSUPP);
> +               goto queue_exit;
> +       }
> +
>          if ((bio->bi_opf & REQ_POLLED) && !blk_mq_can_poll(q)) {
>                  bio_endio_status(bio, BLK_STS_NOTSUPP);
>                  goto queue_exit;
> diff --git a/block/fops.c b/block/fops.c
> index e9da48ab73be..6c6700df943c 100644
> --- a/block/fops.c
> +++ b/block/fops.c
> @@ -976,6 +976,8 @@ static int blkdev_init_dma_buf_io_ctx(struct file *file,
>                  return -EINVAL;
>          if (!disk->fops->init_dma_buf_io_ctx)
>                  return -EOPNOTSUPP;
> +       if (bdev_has_integrity_csum(bdev))
> +               return -EOPNOTSUPP;
>          return disk->fops->init_dma_buf_io_ctx(bdev, ctx);
>   }

Can you send a separate patch? I've queued this series up for some
testing.

-- 
Jens Axboe