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Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.1 Subject: Re: [PATCH v9 2/8] iov_iter: Add a function to extract a page list from an iterator Content-Language: en-US To: David Howells , Al Viro , Christoph Hellwig CC: Matthew Wilcox , Jens Axboe , "Jan Kara" , Jeff Layton , David Hildenbrand , Jason Gunthorpe , Logan Gunthorpe , , , , "Christoph Hellwig" , References: <20230124170108.1070389-1-dhowells@redhat.com> <20230124170108.1070389-3-dhowells@redhat.com> From: John Hubbard In-Reply-To: <20230124170108.1070389-3-dhowells@redhat.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.126.231.37] X-ClientProxiedBy: rnnvmail201.nvidia.com (10.129.68.8) To rnnvmail201.nvidia.com (10.129.68.8) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM6NAM11FT034:EE_|SJ2PR12MB7991:EE_ X-MS-Office365-Filtering-Correlation-Id: 3c8554d5-0b05-4f59-f95a-08dafe4ca112 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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This does > + * not get references on the pages, nor does it get a pin on them. > + */ > +static ssize_t iov_iter_extract_bvec_pages(struct iov_iter *i, > + struct page ***pages, size_t maxsize, > + unsigned int maxpages, > + unsigned int extraction_flags, > + size_t *offset0) > +{ > + struct page **p, *page; > + size_t skip = i->iov_offset, offset; > + int k; > + > + for (;;) { > + if (i->nr_segs == 0) > + return 0; > + maxsize = min(maxsize, i->bvec->bv_len - skip); > + if (maxsize) > + break; > + i->iov_offset = 0; > + i->nr_segs--; > + i->kvec++; > + skip = 0; > + } > + > + skip += i->bvec->bv_offset; > + page = i->bvec->bv_page + skip / PAGE_SIZE; > + offset = skip % PAGE_SIZE; > + *offset0 = offset; > + > + maxpages = want_pages_array(pages, maxsize, offset, maxpages); > + if (!maxpages) > + return -ENOMEM; Is it OK that the iov_iter position has been advanced, and left that way, in the case of an early -ENOMEM return here? thanks, -- John Hubbard NVIDIA