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Fri, 26 May 2023 17:41:47 -0400 X-MC-Unique: GRqTbWv-PT2iy4i50bmzWQ-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 A45FB811E7C; Fri, 26 May 2023 21:41:46 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.39.192.68]) by smtp.corp.redhat.com (Postfix) with ESMTP id F0C92140E961; Fri, 26 May 2023 21:41:43 +0000 (UTC) From: David Howells To: Christoph Hellwig , David Hildenbrand , Lorenzo Stoakes Cc: David Howells , Jens Axboe , Al Viro , Matthew Wilcox , Jan Kara , Jeff Layton , 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 Subject: [PATCH v4 0/3] block: Make old dio use iov_iter_extract_pages() and page pinning Date: Fri, 26 May 2023 22:41:39 +0100 Message-Id: <20230526214142.958751-1-dhowells@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 6F98A8000F X-Stat-Signature: 479hahnituq39pz681sc14zc3hj9k5u8 X-Rspam-User: X-HE-Tag: 1685137309-661909 X-HE-Meta: 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 WNCj4v3Z ulYuMH9NNKMrlCeKQKijxCpDlFRjEryKD/tMP38qYHpMnfaptJpYexb2BA2AxPFw8B7olHdYzpNMh8azccdkuLw0NY0CBHoZWEQDWngI90oTQehTToL4VGk+074H4dsanGGQtpOqZmJULXJ2Il+0lPDBRn2VXOiKX07xD/I+8bqjqkEJA1KdTsZ8w6uzDLa27AsF3QZVow8LW/gRPG5pSwcyXT7xlRi8pWmi1X3lYi34lHPES40QqTnl2UzhQclzeZXR6KNWjaCk0/cu6zH5jP0hoPt1lXt1fu5iEXIQ4ozj8hUm+C7tALLfAk4jcvPPlff6A0JIY44y8jM6dkDejAvrAsQ== 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: Hi Christoph, David, Lorenzo, Here are three patches that go on top of the similar patches for bio structs now in the block tree that make the old block direct-IO code use iov_iter_extract_pages() and page pinning. There are three patches: (1) Make page pinning neither add nor remove a pin to/from a ZERO_PAGE, thereby allowing the dio code to insert zero pages in the middle of dealing with pinned pages. This also mitigates a potential problem whereby userspace could force the overrun the pin counter of a zero page. A pair of functions are provided to wrap the testing of a page or folio to see if it is a zero page. (2) Provide a function to allow an additional pin to be taken on a page we already have pinned (and do nothing for a zero page). (3) Switch direct-io.c over to using page pinning and to use iov_iter_extract_pages() so that pages from non-user-backed iterators aren't pinned. I've pushed the patches here also: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=iov-old-dio David Changes ======= ver #4) - Use _inc rather than _add ops when we're just adding 1. ver #3) - Move is_zero_page() and is_zero_folio() to mm.h for dependency reasons. - Add more comments and adjust the docs about pinning zero pages. - Rename page_get_additional_pin() to folio_add_pin(). - Use is_zero_folio() in folio_add_pin(). - Rename need_unpin to is_pinned in struct dio. ver #2) - Fix use of ZERO_PAGE(). - Add wrappers for testing if a page is a zero page. - Return the zero page obtained, not ZERO_PAGE(0) unconditionally. - Need to set BIO_PAGE_PINNED conditionally, and not BIO_PAGE_REFFED. Link: https://lore.kernel.org/r/ZGxfrOLZ4aN9/MvE@infradead.org/ [1] Link: https://lore.kernel.org/r/20230525155102.87353-1-dhowells@redhat.com/ # v1 Link: https://lore.kernel.org/r/20230525223953.225496-1-dhowells@redhat.com/ # v2 Link: https://lore.kernel.org/r/20230526112859.654506-1-dhowells@redhat.com/ # v3 David Howells (3): mm: Don't pin ZERO_PAGE in pin_user_pages() mm: Provide a function to get an additional pin on a page block: Use iov_iter_extract_pages() and page pinning in direct-io.c Documentation/core-api/pin_user_pages.rst | 6 ++ fs/direct-io.c | 72 ++++++++++++++--------- include/linux/mm.h | 27 ++++++++- mm/gup.c | 58 +++++++++++++++++- 4 files changed, 131 insertions(+), 32 deletions(-)