From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 434FCC25B4E for ; Fri, 20 Jan 2023 17:56:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230138AbjATR4u (ORCPT ); Fri, 20 Jan 2023 12:56:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46680 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229786AbjATR4s (ORCPT ); Fri, 20 Jan 2023 12:56:48 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F773366A3 for ; Fri, 20 Jan 2023 09:56:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1674237367; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=L1vbMszv9II0pr/36LhZgm3t0G5zZlJBs1R5Ur/EGww=; b=CKfWbxXeBa7aMnhtztYh99aPfvRIcOhvdqrCfjg0FBMuxF4NoHiQ0ImhAy9oLVAnBgTXdw ShViXthNEi/hVZ/dSDOUSe7T9McLhTI43VXoeJyfhuW8+y++PYgxCHoKga9ru0YFPnPoce t+4NjGvp/IjAcl4q416U0101aPkjRsE= 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-160-JeBkd2PCM0urfNQeCIc4vA-1; Fri, 20 Jan 2023 12:56:04 -0500 X-MC-Unique: JeBkd2PCM0urfNQeCIc4vA-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 8474B802C1D; Fri, 20 Jan 2023 17:56:02 +0000 (UTC) Received: from warthog.procyon.org.uk.com (unknown [10.33.36.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id 31E7253AA; Fri, 20 Jan 2023 17:56:01 +0000 (UTC) From: David Howells To: Al Viro , Christoph Hellwig Cc: David Howells , Matthew Wilcox , Jens Axboe , Jan Kara , Jeff Layton , Logan Gunthorpe , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v7 0/8] iov_iter: Improve page extraction (ref, pin or just list) Date: Fri, 20 Jan 2023 17:55:48 +0000 Message-Id: <20230120175556.3556978-1-dhowells@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Al, Christoph, Here are patches to provide support for extracting pages from an iov_iter and a patch to use the primary extraction function in the block layer bio code. The patches make the following changes: (1) 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 and the I/O direction. Add a function, iov_iter_extract_mode() that will indicate from the iterator type and the I/O direction how the cleanup is to be performed, returning FOLL_GET, FOLL_PIN or 0. (2) Add a function, folio_put_unpin(), and a wrapper, page_put_unpin(), that take a page and the return from iov_iter_extract_mode() and do the right thing to clean up the page. (3) Make the bio struct carry a pair of flags to indicate the cleanup mode. BIO_NO_PAGE_REF is replaced with BIO_PAGE_REFFED (equivalent to FOLL_GET) and BIO_PAGE_PINNED (equivalent to BIO_PAGE_PINNED) is added. (4) Add a function, bio_release_page(), to release a page appropriately to the cleanup mode indicated by the BIO_PAGE_* flags. (5) Make the iter-to-bio code use iov_iter_extract_pages() to retain the pages appropriately and clean them up later. (6) Fix bio_flagged() so that it doesn't prevent a gcc optimisation. (7) Renumber FOLL_GET and FOLL_PIN down so that they're at bits 0 and 1 and coincident with BIO_PAGE_REFFED and BIO_PAGE_PINNED. The compiler can then optimise on that. Also, it's probably going to be necessary to embed these in the page pointer in sk_buff fragments. This patch can go independently through the mm tree. Changes: ======== 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. I've pushed the patches (excluding the two WIP networking patches) here also: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=iov-extract David Link: https://lore.kernel.org/r/Y3zFzdWnWlEJ8X8/@infradead.org/ [1] 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 David Howells (8): iov_iter: Define flags to qualify page extraction. iov_iter: Add a function to extract a page list from an iterator mm: Provide a helper to drop a pin/ref on a page block: Rename BIO_NO_PAGE_REF to BIO_PAGE_REFFED and invert the meaning block: Add BIO_PAGE_PINNED block: Make bio structs pin pages rather than ref'ing if appropriate block: Fix bio_flagged() so that gcc can better optimise it mm: Renumber FOLL_GET and FOLL_PIN down block/bio.c | 43 ++-- block/blk-map.c | 26 +-- block/blk.h | 29 +++ fs/iomap/direct-io.c | 1 - include/linux/bio.h | 5 +- include/linux/blk_types.h | 3 +- include/linux/mm.h | 17 +- include/linux/uio.h | 35 ++- lib/iov_iter.c | 438 +++++++++++++++++++++++++++++++++++++- mm/gup.c | 22 ++ 10 files changed, 571 insertions(+), 48 deletions(-)