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Wed, 15 Mar 2023 12:36:47 -0400 X-MC-Unique: xwMSkeoeMNWvPvIQXGfjEA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 02AAC88B7A7; Wed, 15 Mar 2023 16:36:38 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.18]) by smtp.corp.redhat.com (Postfix) with ESMTP id D85421121314; Wed, 15 Mar 2023 16:36:35 +0000 (UTC) From: David Howells To: Jens Axboe , Al Viro , Christoph Hellwig Cc: David Howells , Matthew Wilcox , Jan Kara , Jeff Layton , David Hildenbrand , Jason Gunthorpe , Logan Gunthorpe , Hillf Danton , Christian Brauner , Linus Torvalds , 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 v19 15/15] block: convert bio_map_user_iov to use iov_iter_extract_pages Date: Wed, 15 Mar 2023 16:35:49 +0000 Message-Id: <20230315163549.295454-16-dhowells@redhat.com> In-Reply-To: <20230315163549.295454-1-dhowells@redhat.com> References: <20230315163549.295454-1-dhowells@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 X-Rspamd-Queue-Id: 3E13D40027 X-Stat-Signature: dtdtqa4wgi8qdn77hn9ayqug1ywcqkte X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1678898211-714225 X-HE-Meta: U2FsdGVkX18qzlLUqb48AVX0xIe5UGKOuGPqYAcNQWDTAwMC/R06WEDM7MIMf7sZRg2S3bzmiui0Dciz4JiP4LCoe2EzQP6n7MJ9jW6Vx/eIMeHqVdztOWHp2vke2MkaAkF7xcB2ECdVsNmtGsmltPOFG/e+aWyJA5SSA3rWpRHkR1Uy8Muqi180fZ2QzfK4ILfGTkPErz/ZW9Ojxg/LKWUniZjXthZ7uuedDmAcY9AxRfTTE3fZX3f5EeZDJoaptAld+C5kPfoBXUGe2kbVNXPqzr+o86X+9qELC6FjxBtxPb4MZzU0BOfXHaJsU8YvdSeiQtOz76HwyIUghdaujSyHX1BwwrWrsrUirBXWR7735qgC7wSc5itnQCexjVKty6hKq9YXM6Aral1XHno0V3d6n5LQppjUD/rMCYkjcGIT84p7lcF3+umLNKWcJ3trZpzGzSPllAfbTLWmaf6a9eJwp2tskgYJp9u3/BLJlkjvcxjSw+J8IQ7trxQbI6+FXjzbKxPBssBkKgzHypgJN5cjQ+nVGQMFQHISTQUtL1sDizq46w+JPujr+7vbfMvBQPZ9L4Bf5KCZqKnXCbMCtSeYwSVlHbj1/nusVamNAvdliJpu4/dOiEjwbbb4ji2stOjhDbVYj+RPMeK+e6u6DYtIEze/fcdXsVpw2xasrNWm/kwVsj8/g21z4i3Y6gZqLYTDPorZk2XusE3gSxfDPWBL7Z+rYL4orLYQlsRODt8hKyig7RjZAm4UXOOiAsuSkHMVQqucIG9PP2uCUGbZCPDcrm0wQQPiDDnlnYUwdPfqJNkEaQSMZMoSuIiNQ4giiW1KCa9HrpV9lg3Bv81BhwxtF6yvirdagNRn3Bolz1yPiL7OcUGItuQmRud+foij3S1pYhcWaQHvC+C84DfLOct+cCGpRFuy8r165i1C6LCQ9vnIpwn9zaV0Mp/07a9LinIo37FvgEj7W/pkDNv m1eUVNxj 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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 c77fdb1fbda7..7b12f4bb4d4c 100644 --- a/block/blk-map.c +++ b/block/blk-map.c @@ -280,22 +280,21 @@ 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; @@ -317,7 +316,7 @@ 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; } @@ -329,7 +328,7 @@ 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? */