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([2a01:4b00:bd21:4f00:7cc6:d3ca:494:116c]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e71b80ecbsm2527884f8f.35.2026.10.30.03.26.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 30 Oct 2026 03:26:08 -0700 (PDT) Message-ID: Date: Fri, 30 Oct 2026 10:26:09 +0000 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] block: only fail dma-buf bios that need block layer PI To: Kyle Bader , Jens Axboe Cc: Kyle Bader , Anuj Gupta , Kanchan Joshi , Christoph Hellwig , Keith Busch , "Martin K. Petersen" , Tushar Gohad , linux-block@vger.kernel.org, io-uring@vger.kernel.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org References: <20261029155821.2983229-1-kbader@redhat.com> Content-Language: en-US From: Pavel Begunkov In-Reply-To: <20261029155821.2983229-1-kbader@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/29/26 15:58, Kyle Bader wrote: > From: Kyle Bader > > All dma-buf (P2P) I/O to a device with integrity data is rejected > today, at registration and in blk_mq_submit_bio(). Only a bio for which > the block layer generates or verifies PI needs that. The block layer > then walks the bio_vecs, and a dma-buf bio has none. > > Reject only those bios, and remove the check at registration. Then a > submitter that attaches its own PI, for example with > IORING_RW_ATTR_FLAG_PI, can do dma-buf I/O to such a device. Looks good, Reviewed-by: Pavel Begunkov It's also enticing to shove it under the existing bio_integrity_action() check, but it can be done later. > Link: https://lore.kernel.org/all/bbb87d6b-b7a3-487a-8be4-27f3f9ce4a1b@samsung.com/ > Assisted-by: LLM > Reviewed-by: Anuj Gupta > Signed-off-by: Kyle Bader > --- > v2: a shorter commit message (Christoph), and Anuj's Reviewed-by. The > code is the same as in v1, so the tests of v1 still apply. > > v1: https://lore.kernel.org/all/20261028181412.1919506-1-kbader@redhat.com/ > > block/blk-mq.c | 9 ++++++++- > block/fops.c | 2 -- > 2 files changed, 8 insertions(+), 3 deletions(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 7fff1305b..3fc9fdeb3 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -3138,8 +3138,15 @@ void blk_mq_submit_bio(struct bio *bio) > goto queue_exit; > } > > + /* > + * The block layer cannot generate or verify PI for a dma-buf bio, as > + * that walks the data pages. Only fail the bio if it needs that, not > + * if the submitter attached its own integrity payload or if PI > + * generation or verification is turned off for the device. > + */ > if (unlikely(op_is_dmabuf(bio->bi_opf) && > - bdev_has_integrity_csum(bio->bi_bdev))) { > + bdev_has_integrity_csum(bio->bi_bdev) && > + (bio_integrity_action(bio) & BI_ACT_CHECK))) { > bio_endio_status(bio, BLK_STS_NOTSUPP); > goto queue_exit; > } > diff --git a/block/fops.c b/block/fops.c > index 01bc8afe3..5c8024011 100644 > --- a/block/fops.c > +++ b/block/fops.c > @@ -947,8 +947,6 @@ 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); > } > > > base-commit: 45b716456dd99488a0cef58482120dc0474aa696 -- Pavel Begunkov