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Wed, 25 Jan 2023 16:07:26 -0500 X-MC-Unique: R8pex_C2NICT8VgrohPLJQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 9A1591C0A58E; Wed, 25 Jan 2023 21:07:25 +0000 (UTC) Received: from warthog.procyon.org.uk.com (unknown [10.33.36.97]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9317A14171BB; Wed, 25 Jan 2023 21:07:23 +0000 (UTC) From: David Howells To: Al Viro , Christoph Hellwig Cc: David Howells , Matthew Wilcox , Jens Axboe , Jan Kara , Jeff Layton , David Hildenbrand , Jason Gunthorpe , Logan Gunthorpe , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christoph Hellwig , John Hubbard Subject: [PATCH v10 8/8] block: convert bio_map_user_iov to use iov_iter_extract_pages Date: Wed, 25 Jan 2023 21:06:57 +0000 Message-Id: <20230125210657.2335748-9-dhowells@redhat.com> In-Reply-To: <20230125210657.2335748-1-dhowells@redhat.com> References: <20230125210657.2335748-1-dhowells@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 X-Rspam-User: X-Rspamd-Queue-Id: 882C61A0010 X-Rspamd-Server: rspam01 X-Stat-Signature: bqsoaumi3g4kzupnb6fjjy4syzm13mxj X-HE-Tag: 1674680850-146377 X-HE-Meta: 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 D2Yqh9AF 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: This will pin pages or leave them unaltered rather than getting a ref on them as appropriate to the iterator. The pages need to be pinned for DIO rather than having refs taken on them to prevent VM copy-on-write from malfunctioning during a concurrent fork() (the result of the I/O could otherwise end up being visible to/affected by the child process). Signed-off-by: David Howells Reviewed-by: Christoph Hellwig Reviewed-by: John Hubbard cc: Al Viro cc: Jens Axboe cc: Jan Kara cc: Matthew Wilcox cc: Logan Gunthorpe cc: linux-block@vger.kernel.org --- Notes: ver #10) - Drop bio_set_cleanup_mode(), open coding it instead. ver #8) - Split the patch up a bit [hch]. - We should only be using pinned/non-pinned pages and not ref'd pages, so adjust the comments appropriately. ver #7) - Don't treat BIO_PAGE_REFFED/PINNED as being the same as FOLL_GET/PIN. ver #5) - Transcribe the FOLL_* flags returned by iov_iter_extract_pages() to BIO_* flags and got rid of bi_cleanup_mode. - Replaced BIO_NO_PAGE_REF to BIO_PAGE_REFFED in the preceding patch. block/blk-map.c | 23 +++++++++++------------ 1 file changed, 11 insertions(+), 12 deletions(-) diff --git a/block/blk-map.c b/block/blk-map.c index 0e2b0a861ba3..9c7ccea3f334 100644 --- a/block/blk-map.c +++ b/block/blk-map.c @@ -281,22 +281,21 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter, if (blk_queue_pci_p2pdma(rq->q)) extraction_flags |= ITER_ALLOW_P2PDMA; + if (iov_iter_extract_will_pin(iter)) + bio_set_flag(bio, BIO_PAGE_PINNED); - bio_set_flag(bio, BIO_PAGE_REFFED); while (iov_iter_count(iter)) { - struct page **pages, *stack_pages[UIO_FASTIOV]; + struct page *stack_pages[UIO_FASTIOV]; + struct page **pages = stack_pages; ssize_t bytes; size_t offs; int npages; - if (nr_vecs <= ARRAY_SIZE(stack_pages)) { - pages = stack_pages; - bytes = iov_iter_get_pages(iter, pages, LONG_MAX, - nr_vecs, &offs, extraction_flags); - } else { - bytes = iov_iter_get_pages_alloc(iter, &pages, - LONG_MAX, &offs, extraction_flags); - } + if (nr_vecs > ARRAY_SIZE(stack_pages)) + pages = NULL; + + bytes = iov_iter_extract_pages(iter, &pages, LONG_MAX, + nr_vecs, extraction_flags, &offs); if (unlikely(bytes <= 0)) { ret = bytes ? bytes : -EFAULT; goto out_unmap; @@ -318,7 +317,7 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter, if (!bio_add_hw_page(rq->q, bio, page, n, offs, max_sectors, &same_page)) { if (same_page) - put_page(page); + bio_release_page(bio, page); break; } @@ -330,7 +329,7 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter, * release the pages we didn't map into the bio, if any */ while (j < npages) - put_page(pages[j++]); + bio_release_page(bio, pages[j++]); if (pages != stack_pages) kvfree(pages); /* couldn't stuff something into bio? */