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

[Anuj Gupta/Anuj Gupta]

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);
  }