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Fri, 18 Apr 2025 04:09:44 +0200 Message-ID: Date: Fri, 18 Apr 2025 11:39:41 +0930 Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 5/8] btrfs: simplify bvec iteration in index_one_bio To: Christoph Hellwig , Qu Wenruo Cc: linux-btrfs@vger.kernel.org References: <20250409111055.3640328-1-hch@lst.de> <20250409111055.3640328-6-hch@lst.de> Content-Language: en-US From: Qu Wenruo Autocrypt: addr=quwenruo.btrfs@gmx.com; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNIlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT7CwJQEEwEIAD4CGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCZxF1YAUJEP5a sQAKCRDCPZHzoSX+qF+mB/9gXu9C3BV0omDZBDWevJHxpWpOwQ8DxZEbk9b9LcrQlWdhFhyn xi+l5lRziV9ZGyYXp7N35a9t7GQJndMCFUWYoEa+1NCuxDs6bslfrCaGEGG/+wd6oIPb85xo naxnQ+SQtYLUFbU77WkUPaaIU8hH2BAfn9ZSDX9lIxheQE8ZYGGmo4wYpnN7/hSXALD7+oun tZljjGNT1o+/B8WVZtw/YZuCuHgZeaFdhcV2jsz7+iGb+LsqzHuznrXqbyUQgQT9kn8ZYFNW 7tf+LNxXuwedzRag4fxtR+5GVvJ41Oh/eygp8VqiMAtnFYaSlb9sjia1Mh+m+OBFeuXjgGlG VvQFzsBNBFnVga8BCACqU+th4Esy/c8BnvliFAjAfpzhI1wH76FD1MJPmAhA3DnX5JDORcga CbPEwhLj1xlwTgpeT+QfDmGJ5B5BlrrQFZVE1fChEjiJvyiSAO4yQPkrPVYTI7Xj34FnscPj /IrRUUka68MlHxPtFnAHr25VIuOS41lmYKYNwPNLRz9Ik6DmeTG3WJO2BQRNvXA0pXrJH1fN GSsRb+pKEKHKtL1803x71zQxCwLh+zLP1iXHVM5j8gX9zqupigQR/Cel2XPS44zWcDW8r7B0 q1eW4Jrv0x19p4P923voqn+joIAostyNTUjCeSrUdKth9jcdlam9X2DziA/DHDFfS5eq4fEv ABEBAAHCwHwEGAEIACYCGwwWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCZxF1gQUJEP5a0gAK CRDCPZHzoSX+qHGpB/kB8A7M7KGL5qzat+jBRoLwB0Y3Zax0QWuANVdZM3eJDlKJKJ4HKzjo B2Pcn4JXL2apSan2uJftaMbNQbwotvabLXkE7cPpnppnBq7iovmBw++/d8zQjLQLWInQ5kNq Vmi36kmq8o5c0f97QVjMryHlmSlEZ2Wwc1kURAe4lsRG2dNeAd4CAqmTw0cMIrR6R/Dpt3ma +8oGXJOmwWuDFKNV4G2XLKcghqrtcRf2zAGNogg3KulCykHHripG3kPKsb7fYVcSQtlt5R6v HZStaZBzw4PcDiaAF3pPDBd+0fIKS6BlpeNRSFG94RYrt84Qw77JWDOAZsyNfEIEE0J6LSR/ In-Reply-To: <20250409111055.3640328-6-hch@lst.de> Content-Type: text/plain; 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> - struct bio_vec bvec; > - struct bvec_iter iter; > + struct bvec_iter iter =3D bio->bi_iter; > u32 offset =3D (bio->bi_iter.bi_sector << SECTOR_SHIFT) - > rbio->bioc->full_stripe_logical; > =20 > - bio_for_each_segment(bvec, bio, iter) { > - u32 bvec_offset; > + while (iter.bi_size) { > + int index =3D offset / sectorsize; The value @offset is no longer updated, this means only the first sector= =20 of the current bio will be updated, and it's updated several times,=20 resulting incorrect location. Furthermore, for full stripe write since we do not allocate pages for=20 the stripes_pages[], we will got incorrect bio_sectors[] pointing to NULL. This will crash rmw_rbio(), easily reproduced by btrfs/011. I'll also fix it in my local branch. Thanks, Qu > + struct sector_ptr *sector =3D &rbio->bio_sectors[index]; > + struct bio_vec bv =3D bio_iter_iovec(bio, iter); > =20 > - for (bvec_offset =3D 0; bvec_offset < bvec.bv_len; > - bvec_offset +=3D sectorsize, offset +=3D sectorsize) { > - int index =3D offset / sectorsize; > - struct sector_ptr *sector =3D &rbio->bio_sectors[index]; > + sector->page =3D bv.bv_page; > + sector->pgoff =3D bv.bv_offset; > + ASSERT(sector->pgoff < PAGE_SIZE); > =20 > - sector->page =3D bvec.bv_page; > - sector->pgoff =3D bvec.bv_offset + bvec_offset; > - ASSERT(sector->pgoff < PAGE_SIZE); > - } > + bio_advance_iter_single(bio, &iter, sectorsize); > } > } > =20