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[4.53.155.98]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a0976ca5f9sm1275340a91.14.2026.09.23.16.37.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 23 Sep 2026 16:37:51 -0700 (PDT) Message-ID: Date: Wed, 23 Sep 2026 16:37:50 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 5/8] block: fail a short atomic pin in bio_iov_iter_get_pages() To: Hannes Reinecke , Jens Axboe , Christoph Hellwig , Johannes Thumshirn , Luis Chamberlain , Hannes Reinecke , "Matthew Wilcox (Oracle)" , John Garry , Christian Brauner , "Darrick J. Wong" , Keith Busch , "Martin K. Petersen" Cc: Shin'ichiro Kawasaki , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Sashiko References: <20260921-blkdev-fixes-v4-0-e2801f71ede9@columbia.edu> <20260921-blkdev-fixes-v4-5-e2801f71ede9@columbia.edu> <341ec217-4b3b-49aa-9481-4cf7e8952228@suse.de> Content-Language: en-US From: Tal Zussman In-Reply-To: <341ec217-4b3b-49aa-9481-4cf7e8952228@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Proofpoint-Spam-Info: AW1haW4tMjYwOTIzMDA5NyBTYWx0ZWRfXyeFd1kfLtz4/ l3Cj1sF31x7+5/THd8SkTcLRzFUxN6abH1GrK1SAmb11PmEg/vgMzmrNHnw73qs25kkf52shs7c s2DdJtkp5yIRJtRcLjax3kislciQ0j6Zt/SG3ZcMgoq0cQXllA3x X-Proofpoint-ORIG-GUID: 7BNfxLII0pfnmlhBqo-hJtuGDmqYbOgE X-Authority-Analysis: v=2.4 cv=HcaB3SE8 c=1 sm=1 tr=0 ts=6ab462d1 cx=c_pps a=vVfyC5vLCtgYJKYeQD43oA==:117 a=6aZ3Ysb2zzbY2sELL/OBJw==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=x7bEGLp0ZPQA:10 a=A0y_DWxS2BwA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Da8U98TiO7q1upZEImrf:22 a=79PYxaXUQd1wl-QFWJnA:22 a=XJsBi8-B-AtTf0VDNmMA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=rl5im9kqc5Lf4LNbBjHf:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTIzMDA5NyBTYWx0ZWRfX2s0jvMUgA9qF RGdcMnL2TxYBixZ4I8hzUXHK2DisupV/wzxVhAuumr+vrnlYorySnKLYS5TMCddMe/s9r/2Zsy+ CgZlzdJliPtBNNpPSGM/j+sHdOQYQyY+sgezeP+277k4jTG3zg3TxE2JWKptFz9XVLJNGjZPMfq ICpk5aILeCjdbRzDwqNP86mca39xll8Uo8hF1DjZ2+np6Ej6YKB8iQP9lJxB5/jtj5NZ8KCvTIn Yd3twwSprOiWb0akl5lCDCC1ZGZSVLvcNp9d+evh4fRgsIYL9qzIY57d3k32r3JVE/5MmDHbtWd B9l0eXPVEPtjvsoAPTZWnzlaR2Z+pUq+MiW6oKCiwHX/IBOAPyNXmoJbcgmoW0a/uA0SQ7FIijy jb41pKaB4V2A2uDtRhM4dB5VxaOWzTZi2NINUDtKT/lC4DRjcXGsXIjNEuO0z/189SQyZmVQg2U qDm5m/zLCDbTLnu/H7w== X-Proofpoint-GUID: 7BNfxLII0pfnmlhBqo-hJtuGDmqYbOgE X-Proofpoint-Virus-Version: vendor=nai engine=6900 definitions=11914 signatures=596817 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=10 adultscore=0 suspectscore=0 phishscore=0 clxscore=1015 lowpriorityscore=10 spamscore=0 priorityscore=1501 impostorscore=10 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609230097 On 9/22/26 1:40 AM, Hannes Reinecke wrote: >> diff --git a/block/bio.c b/block/bio.c >> index f95b63c0604a..14429a5d4e68 100644 >> --- a/block/bio.c >> +++ b/block/bio.c >> @@ -1285,6 +1285,7 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter, >> unsigned mem_align_mask, unsigned len_align_mask) >> { >> iov_iter_extraction_t flags = 0; >> + int ret; >> >> if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED))) >> return -EIO; >> @@ -1304,34 +1305,48 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter, >> flags |= ITER_ALLOW_P2PDMA; >> >> do { >> - ssize_t ret; >> + ssize_t size; >> >> - ret = iov_iter_extract_bvecs(iter, bio->bi_io_vec, >> + size = iov_iter_extract_bvecs(iter, bio->bi_io_vec, >> BIO_MAX_SIZE - bio->bi_iter.bi_size, >> &bio->bi_vcnt, bio->bi_max_vecs, >> mem_align_mask, flags); >> - if (ret <= 0) { >> + if (size <= 0) { >> /* >> * A misaligned vector fails the whole I/O. Release any >> * pages pinned by earlier iterations before returning >> * since this bio won't be submitted to release them. >> */ >> - if (ret == -EINVAL) { >> + if (size == -EINVAL) { >> bio_release_pages(bio, false); >> bio_clear_flag(bio, BIO_PAGE_PINNED); >> bio->bi_vcnt = 0; >> } >> if (!bio->bi_vcnt) >> - return ret; >> + return size; >> break; >> } >> - bio->bi_iter.bi_size += ret; >> + bio->bi_iter.bi_size += size; >> } while (iov_iter_count(iter) && !bio_full(bio, 0)); >> > I would swizzle the use of 'ret' and 'size' here; leaving 'ret' > untouched and use 'size' as the new variable. That will reduce > code churn and makes the patch easier to read. > I'm going to leave this as-is per John's previous request. >> if (is_pci_p2pdma_page(bio->bi_io_vec->bv_page)) >> bio->bi_opf |= REQ_NOMERGE; >> - return bio_iov_iter_align_down(bio, iter, >> + ret = bio_iov_iter_align_down(bio, iter, >> &bio->bi_io_vec[bio->bi_vcnt - 1], len_align_mask); >> + if (ret) >> + return ret; >> + >> + /* >> + * An atomic write is submitted as a single bio, so it has to cover >> + * the whole iterator or it would be torn. >> + */ >> + if ((bio->bi_opf & REQ_ATOMIC) && iov_iter_count(iter)) { >> + bio_release_pages(bio, false); >> + bio_clear_flag(bio, BIO_PAGE_PINNED); >> + bio->bi_vcnt = 0; >> + return -EINVAL; >> + } >> + return 0; >> } >> >> static struct folio *folio_alloc_greedy(gfp_t gfp, size_t *size, >> diff --git a/block/fops.c b/block/fops.c >> index a3a709697b40..90777e8a9a6c 100644 >> --- a/block/fops.c >> +++ b/block/fops.c >> @@ -342,6 +342,12 @@ static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb, >> bio->bi_end_io = blkdev_bio_end_io_async; >> bio->bi_ioprio = iocb->ki_ioprio; >> >> + if (iocb->ki_flags & IOCB_ATOMIC) >> + bio->bi_opf |= REQ_ATOMIC; >> + >> + if (iocb->ki_flags & IOCB_NOWAIT) >> + bio->bi_opf |= REQ_NOWAIT; >> + >> /* >> * Users don't rely on the iterator being in any particular >> * state for async I/O returning -EIOCBQUEUED, hence we can >> @@ -371,12 +377,6 @@ static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb, >> goto out_bio_put; >> } >> >> - if (iocb->ki_flags & IOCB_ATOMIC) >> - bio->bi_opf |= REQ_ATOMIC; >> - >> - if (iocb->ki_flags & IOCB_NOWAIT) >> - bio->bi_opf |= REQ_NOWAIT; >> - >> if (iocb->ki_flags & IOCB_HIPRI) { >> bio->bi_opf |= REQ_POLLED; >> submit_bio(bio); >> > > Otherwise looks good. > Thanks! > Cheers, > > Hannes > -- > Dr. Hannes Reinecke Kernel Storage Architect > hare@suse.de +49 911 74053 688 > SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg > HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich >