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bh=dlH82MTyZ9mEwQh0gAgGnq4n7zKaA3lADhykYJfgTYc=; b=RCdeVaqec2s6QAZQFi13orb8/oHLhmLrxqytcPOKU8yHWM8bYdfxrTbdEiwGEIIA11GuaF 4ST2PP81S/De3ZsFntXRKYx4+BBVCoTP6vvhjNaRwoXTzV74a6FRpEwtJkO0WwIYr4r4Bf Z57vlNfymIkX2ps0/w+xLEg6WPXTaaM= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-102-500ECHMmOyWoNXxaItq69w-1; Tue, 07 Feb 2023 12:13:12 -0500 X-MC-Unique: 500ECHMmOyWoNXxaItq69w-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2EBEC8027FD; Tue, 7 Feb 2023 17:13:12 +0000 (UTC) Received: from warthog.procyon.org.uk.com (unknown [10.33.36.97]) by smtp.corp.redhat.com (Postfix) with ESMTP id 29BC618EC5; Tue, 7 Feb 2023 17:13:10 +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 , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v12 00/10] iov_iter: Improve page extraction (pin or just list) Date: Tue, 7 Feb 2023 17:12:55 +0000 Message-Id: <20230207171305.3716974-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: BDA0414000F X-Stat-Signature: rmeteeettiehs3wnfeyy1dae3mg5ihwi X-Rspam-User: X-HE-Tag: 1675789996-730432 X-HE-Meta: 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 MaLeMfG3 jfcwNTbynONgZsKFDPXxY6BgjeQlyomHqBQl3GThrA3Tfpe5RhRSdbLKWrWNY6/2zSk49WNnhIl2jrDOyixKudgsGBJoLuUqYqC4OUaZBQ8Ys4jBjLPAPEJcSCnzJjEAzePRhb/ghYyBE+vJ9hGHcB2mFQ5/ym9RYiAr4CPzxxK50Iy1MJAkZT69cYvjkc9wJQuMw7aexyEDBaB8dxC1wIuTa3EmtNP6KMReEnlQ0Px/s9kOYzAySn+rhWfHzcZdwgAp4mv1P7A/WMTnzj3EuLrljt0rIxXCA4pge4u+vclI+VcovmO20xU67d+W10+pIaWsnNczBuNI8ac0uHmiE8oH/QRFxQFBHaNS5rmdyWfwQIhNPekYIGlofKVgydPYjc2LXMQLm1NVGUyZEaWJ1jCBhXK9J5LHhMLl03sGOAcikPgbv30yoDulK3ud7LFvGssVK 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 Jens, Al, Christoph, Here are patches to provide support for extracting pages from an iov_iter and to use this in the extraction functions in the block layer bio code. The patches make the following changes: (1) Change generic_file_splice_read() to load up an ITER_BVEC iterator with sufficient pages and use that rather than using an ITER_PIPE. This avoids a problem[2] when __iomap_dio_rw() calls iov_iter_revert() to shorten an iterator when it races with truncation. The reversion causes the pipe iterator to prematurely release the pages it was retaining - despite the read still being in progress. This caused memory corruption. (2) Remove ITER_PIPE and its paraphernalia as generic_file_splice_read() was the only user. (3) Add a function, iov_iter_extract_pages() to replace iov_iter_get_pages*() that gets refs, pins or just lists the pages as appropriate to the iterator type. Add a function, iov_iter_extract_will_pin() that will indicate from the iterator type how the cleanup is to be performed, returning true if the pages will need unpinning, false otherwise. (4) Make the bio struct carry a pair of flags to indicate the cleanup mode. BIO_NO_PAGE_REF is replaced with BIO_PAGE_REFFED (indicating FOLL_GET was used) and BIO_PAGE_PINNED (indicating FOLL_PIN was used) is added. BIO_PAGE_REFFED will go away, but at the moment fs/direct-io.c sets it and this series does not fully address that file. (5) Add a function, bio_release_page(), to release a page appropriately to the cleanup mode indicated by the BIO_PAGE_* flags. (6) Make the iter-to-bio code use iov_iter_extract_pages() to retain the pages appropriately and clean them up later. (7) Fix bio_flagged() so that it doesn't prevent a gcc optimisation. I've pushed the patches here also: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=iov-extract and tagged it with iov-extract-20230207 David Changes: ======== ver #12) - Added the missing __bitwise on the iov_iter_extraction_t typedef. - Rebased on -rc7. - Don't specify FOLL_PIN to pin_user_pages_fast(). - Inserted patch at front to fix race between DIO read and truncation that caused memory corruption when iov_iter_revert() got called on an ITER_PIPE iterator[2]. - Inserted a patch after that to remove the now-unused ITER_PIPE and its helper functions. - Removed the ITER_PIPE bits from iov_iter_extract_pages(). ver #11) - Fix iov_iter_extract_kvec_pages() to include the offset into the page in the returned starting offset. - Use __bitwise for the extraction flags ver #10) - Fix use of i->kvec in iov_iter_extract_bvec_pages() to be i->bvec. - Drop bio_set_cleanup_mode(), open coding it instead. ver #9) - It's now not permitted to use FOLL_PIN outside of mm/, so: - Change iov_iter_extract_mode() into iov_iter_extract_will_pin() and return true/false instead of FOLL_PIN/0. - Drop of folio_put_unpin() and page_put_unpin() and instead call unpin_user_page() (and put_page()) directly as necessary. - Make __bio_release_pages() call bio_release_page() instead of unpin_user_page() as there's no BIO_* -> FOLL_* translation to do. - Drop the FOLL_* renumbering patch. - Change extract_flags to extraction_flags. ver #8) - Import Christoph Hellwig's changes. - Split the conversion-to-extraction patch. - Drop the extract_flags arg from iov_iter_extract_mode(). - Don't default bios to BIO_PAGE_REFFED, but set explicitly. - Switch FOLL_PIN and FOLL_GET when renumbering so PIN is at bit 0. - Switch BIO_PAGE_PINNED and BIO_PAGE_REFFED so PINNED is at bit 0. - We should always be using FOLL_PIN (not FOLL_GET) for DIO, so adjust the patches for that. ver #7) - For now, drop the parts to pass the I/O direction to iov_iter_*pages*() as it turned out to be a lot more complicated, with places not setting IOCB_WRITE when they should, for example. - Drop all the patches that changed things other then the block layer's bio handling. The netfslib and cifs changes can go into a separate patchset. - Add support for extracting pages from KVEC-type iterators. - When extracting from BVEC/KVEC, skip over empty vecs at the front. ver #6) - Fix write() syscall and co. not setting IOCB_WRITE. - Added iocb_is_read() and iocb_is_write() to check IOCB_WRITE. - Use op_is_write() in bio_copy_user_iov(). - Drop the iterator direction checks from smbd_recv(). - Define FOLL_SOURCE_BUF and FOLL_DEST_BUF and pass them in as part of gup_flags to iov_iter_get/extract_pages*(). - Replace iov_iter_get_pages*2() with iov_iter_get_pages*() and remove. - Add back the function to indicate the cleanup mode. - Drop the cleanup_mode return arg to iov_iter_extract_pages(). - Provide a helper to clean up a page. - Renumbered FOLL_GET and FOLL_PIN and made BIO_PAGE_REFFED/PINNED have the same numerical values, enforced with an assertion. - Converted AF_ALG, SCSI vhost, generic DIO, FUSE, splice to pipe, 9P and NFS. - Added in the patches to make CIFS do top-to-bottom iterators and use various of the added extraction functions. - Added a pair of work-in-progess patches to make sk_buff fragments store FOLL_GET and FOLL_PIN. ver #5) - Replace BIO_NO_PAGE_REF with BIO_PAGE_REFFED and split into own patch. - Transcribe FOLL_GET/PIN into BIO_PAGE_REFFED/PINNED flags. - Add patch to allow bio_flagged() to be combined by gcc. ver #4) - Drop the patch to move the FOLL_* flags to linux/mm_types.h as they're no longer referenced by linux/uio.h. - Add ITER_SOURCE/DEST cleanup patches. - Make iov_iter/netfslib iter extraction patches use ITER_SOURCE/DEST. - Allow additional gup_flags to be passed into iov_iter_extract_pages(). - Add struct bio patch. ver #3) - Switch to using EXPORT_SYMBOL_GPL to prevent indirect 3rd-party access to get/pin_user_pages_fast()[1]. ver #2) - Rolled the extraction cleanup mode query function into the extraction function, returning the indication through the argument list. - Fixed patch 4 (extract to scatterlist) to actually use the new extraction API. Link: https://lore.kernel.org/r/Y3zFzdWnWlEJ8X8/@infradead.org/ [1] Link: https://lore.kernel.org/r/000000000000b0b3c005f3a09383@google.com/ [2] Link: https://lore.kernel.org/r/166697254399.61150.1256557652599252121.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/166722777223.2555743.162508599131141451.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/166732024173.3186319.18204305072070871546.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/166869687556.3723671.10061142538708346995.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/166920902005.1461876.2786264600108839814.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/166997419665.9475.15014699817597102032.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/167305160937.1521586.133299343565358971.stgit@warthog.procyon.org.uk/ # v4 Link: https://lore.kernel.org/r/167344725490.2425628.13771289553670112965.stgit@warthog.procyon.org.uk/ # v5 Link: https://lore.kernel.org/r/167391047703.2311931.8115712773222260073.stgit@warthog.procyon.org.uk/ # v6 Link: https://lore.kernel.org/r/20230120175556.3556978-1-dhowells@redhat.com/ # v7 Link: https://lore.kernel.org/r/20230123173007.325544-1-dhowells@redhat.com/ # v8 Link: https://lore.kernel.org/r/20230124170108.1070389-1-dhowells@redhat.com/ # v9 Link: https://lore.kernel.org/r/20230125210657.2335748-1-dhowells@redhat.com/ # v10 Link: https://lore.kernel.org/r/20230126141626.2809643-1-dhowells@redhat.com/ # v11 Christoph Hellwig (1): block: Replace BIO_NO_PAGE_REF with BIO_PAGE_REFFED with inverted logic David Howells (9): vfs, iomap: Fix generic_file_splice_read() to avoid reversion of ITER_PIPE iov_iter: Kill ITER_PIPE iov_iter: Define flags to qualify page extraction. iov_iter: Add a function to extract a page list from an iterator iomap: Don't get an reference on ZERO_PAGE for direct I/O block zeroing block: Fix bio_flagged() so that gcc can better optimise it block: Add BIO_PAGE_PINNED and associated infrastructure block: Convert bio_iov_iter_get_pages to use iov_iter_extract_pages block: convert bio_map_user_iov to use iov_iter_extract_pages block/bio.c | 33 +- block/blk-map.c | 26 +- block/blk.h | 12 + fs/cifs/file.c | 8 +- fs/direct-io.c | 2 + fs/iomap/direct-io.c | 1 - fs/splice.c | 76 +++- include/linux/bio.h | 5 +- include/linux/blk_types.h | 3 +- include/linux/uio.h | 49 ++- lib/iov_iter.c | 713 +++++++++++++++----------------------- mm/filemap.c | 3 - 12 files changed, 426 insertions(+), 505 deletions(-)