From patchwork Tue Mar 23 22:17:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 12159537 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 784BFC433E4 for ; Tue, 23 Mar 2021 22:18:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5685B61937 for ; Tue, 23 Mar 2021 22:18:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233877AbhCWWSK (ORCPT ); Tue, 23 Mar 2021 18:18:10 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:60489 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233790AbhCWWRk (ORCPT ); Tue, 23 Mar 2021 18:17:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616537859; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=sTQ4e/xAuzcUxTZmFIaQwY/w13lRQrA/qVwc/tZwtw4=; b=OJJm4Tc1gcDd8TZQdMZ0NP8WPF0ojtldG6EfLyMxvCkwxmA7UNa7WtPxvnab9VDsBT13WM 8uSNZgcJa2ELm0Zk8kzNT9/iv2ZVsBt923Kh3pybbv72H8/2ZpEzZZ1NtBKWRcaqzD/GRT CYe7ljpc9PoiynEjD7gn+HCkqstlvjs= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-403-yiMl_McaPYCpOJfY7FAqxQ-1; Tue, 23 Mar 2021 18:17:37 -0400 X-MC-Unique: yiMl_McaPYCpOJfY7FAqxQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 218461853022; Tue, 23 Mar 2021 22:17:35 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-112-58.rdu2.redhat.com [10.10.112.58]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7E0285DEAD; Tue, 23 Mar 2021 22:17:28 +0000 (UTC) Subject: [PATCH v5 00/28] Network fs helper library & fscache kiocb API From: David Howells To: Trond Myklebust , Anna Schumaker , Steve French , Dominique Martinet Cc: Alexander Viro , Jeff Layton , linux-fsdevel@vger.kernel.org, Linus Torvalds , linux-afs@lists.infradead.org, "Matthew Wilcox (Oracle)" , Christoph Hellwig , ceph-devel@vger.kernel.org, linux-mm@kvack.org, Matthew Wilcox , v9fs-developer@lists.sourceforge.net, linux-cifs@vger.kernel.org, linux-cachefs@redhat.com, linux-nfs@vger.kernel.org, dhowells@redhat.com, Jeff Layton , David Wysochanski , "Matthew Wilcox (Oracle)" , Alexander Viro , linux-cachefs@redhat.com, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Tue, 23 Mar 2021 22:17:27 +0000 Message-ID: <161653784755.2770958.11820491619308713741.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Here's a set of patches to do two things: (1) Add a helper library to handle the new VM readahead interface. This is intended to be used unconditionally by the filesystem (whether or not caching is enabled) and provides a common framework for doing caching, transparent huge pages and, in the future, possibly fscrypt and read bandwidth maximisation. It also allows the netfs and the cache to align, expand and slice up a read request from the VM in various ways; the netfs need only provide a function to read a stretch of data to the pagecache and the helper takes care of the rest. (2) Add an alternative fscache/cachfiles I/O API that uses the kiocb facility to do async DIO to transfer data to/from the netfs's pages, rather than using readpage with wait queue snooping on one side and vfs_write() on the other. It also uses less memory, since it doesn't do buffered I/O on the backing file. Note that this uses SEEK_HOLE/SEEK_DATA to locate the data available to be read from the cache. Whilst this is an improvement from the bmap interface, it still has a problem with regard to a modern extent-based filesystem inserting or removing bridging blocks of zeros. Fixing that requires a much greater overhaul. This is a step towards overhauling the fscache API. The change is opt-in on the part of the network filesystem. A netfs should not try to mix the old and the new API because of conflicting ways of handling pages and the PG_fscache page flag and because it would be mixing DIO with buffered I/O. Further, the helper library can't be used with the old API. This does not change any of the fscache cookie handling APIs or the way invalidation is done. In the near term, I intend to deprecate and remove the old I/O API (fscache_allocate_page{,s}(), fscache_read_or_alloc_page{,s}(), fscache_write_page() and fscache_uncache_page()) and eventually replace most of fscache/cachefiles with something simpler and easier to follow. The patchset contains the following parts: (1) Some helper patches, including provision of an ITER_XARRAY iov iterator and a function to do readahead expansion. (2) Patches to add the netfs helper library. (3) A patch to add the fscache/cachefiles kiocb API. (4) Patches to add support in AFS for this. Jeff Layton has patches to add support in Ceph for this. Dave Wysochanski also has patches for NFS for this, though they're not included on this branch as there's an issue with PNFS. With this, AFS without a cache passes all expected xfstests; with a cache, there's an extra failure, but that's also there before these patches. Fixing that probably requires a greater overhaul. Ceph and NFS also pass the expected tests. These patches can be found also on: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=fscache-netfs-lib Changes ======= ver #5: Fixed some review comments from Matthew Wilcox: - Put a comment into netfs_readahead() to indicate why there's a loop that puts, but doesn't unlock, "unconsumed" pages at the end when it could just return said pages to the caller to dispose of[6]. (This is because where those pages are marked consumed). - Use the page_file_mapping() and page_index() helper functions rather than accessing the page struct directly[6]. - Better names for wrangling functions for PG_private_2 and PG_fscache wrangling functions[7]. Came up with {set,end,wait_for}_page_private_2() and aliased these for fscache. Moved the taking of/dropping a page ref for the PG_private_2 flag into the set and end functions. ver #4: Fixed some review comments from Christoph Hellwig, including dropping the export of rw_verify_area()[3] and some minor stuff[4]. Moved the declaration of readahead_expand() to a better location[5]. Rebased to v5.12-rc2 and added a bunch of references into individual commits. Dropped Ceph support - that will go through the maintainer's tree. Added interface documentation for the netfs helper library. ver #3: Rolled in the bug fixes. Adjusted the functions that unlock and wait for PG_fscache according to Linus's suggestion[1]. Hold a ref on a page when PG_fscache is set as per Linus's suggestion[2]. Dropped NFS support and added Ceph support. ver #2: Fixed some bugs and added NFS support. Link: https://lore.kernel.org/r/CAHk-=wh+2gbF7XEjYc=HV9w_2uVzVf7vs60BPz0gFA=+pUm3ww@mail.gmail.com/ [1] Link: https://lore.kernel.org/r/CAHk-=wjgA-74ddehziVk=XAEMTKswPu1Yw4uaro1R3ibs27ztw@mail.gmail.com/ [2] Link: https://lore.kernel.org/r/20210216102614.GA27555@lst.de/ [3] Link: https://lore.kernel.org/r/20210216084230.GA23669@lst.de/ [4] Link: https://lore.kernel.org/r/20210217161358.GM2858050@casper.infradead.org/ [5] Link: https://lore.kernel.org/r/20210321014202.GF3420@casper.infradead.org/ [6] Link: https://lore.kernel.org/r/20210321105309.GG3420@casper.infradead.org/ [7] References ========== These patches have been published for review before, firstly as part of a larger set: Link: https://lore.kernel.org/r/158861203563.340223.7585359869938129395.stgit@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/159465766378.1376105.11619976251039287525.stgit@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/159465784033.1376674.18106463693989811037.stgit@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/159465821598.1377938.2046362270225008168.stgit@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/160588455242.3465195.3214733858273019178.stgit@warthog.procyon.org.uk/ Then as a cut-down set: Link: https://lore.kernel.org/r/161118128472.1232039.11746799833066425131.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/161161025063.2537118.2009249444682241405.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/161340385320.1303470.2392622971006879777.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/161539526152.286939.8589700175877370401.stgit@warthog.procyon.org.uk/ # v4 Proposals/information about the design has been published here: Link: https://lore.kernel.org/r/24942.1573667720@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/2758811.1610621106@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/1441311.1598547738@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/160655.1611012999@warthog.procyon.org.uk/ And requests for information: Link: https://lore.kernel.org/r/3326.1579019665@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/4467.1579020509@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/3577430.1579705075@warthog.procyon.org.uk/ The NFS parts, though not included here, have been tested by someone who's using fscache in production: Link: https://listman.redhat.com/archives/linux-cachefs/2020-December/msg00000.html I've posted partial patches to try and help 9p and cifs along: Link: https://lore.kernel.org/r/1514086.1605697347@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/1794123.1605713481@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/241017.1612263863@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/270998.1612265397@warthog.procyon.org.uk/ David --- David Howells (28): iov_iter: Add ITER_XARRAY mm: Add wait_on_page_writeback_killable() mm: Add set/end/wait functions for PG_private_2 mm: Implement readahead_control pageset expansion netfs: Make a netfs helper module netfs: Documentation for helper library netfs, mm: Move PG_fscache helper funcs to linux/netfs.h netfs, mm: Add set/end/wait_on_page_fscache() aliases netfs: Provide readahead and readpage netfs helpers netfs: Add tracepoints netfs: Gather stats netfs: Add write_begin helper netfs: Define an interface to talk to a cache fscache, cachefiles: Add alternate API to use kiocb for read/write to cache afs: Disable use of the fscache I/O routines afs: Pass page into dirty region helpers to provide THP size afs: Print the operation debug_id when logging an unexpected data version afs: Move key to afs_read struct afs: Don't truncate iter during data fetch afs: Log remote unmarshalling errors afs: Set up the iov_iter before calling afs_extract_data() afs: Use ITER_XARRAY for writing afs: Wait on PG_fscache before modifying/releasing a page afs: Extract writeback extension into its own function afs: Prepare for use of THPs afs: Use the fs operation ops to handle FetchData completion afs: Use new fscache read helper API afs: Use the fscache_write_begin() helper Documentation/filesystems/index.rst | 1 + Documentation/filesystems/netfs_library.rst | 526 +++++++++ fs/Kconfig | 1 + fs/Makefile | 1 + fs/afs/Kconfig | 1 + fs/afs/dir.c | 225 ++-- fs/afs/file.c | 483 ++------ fs/afs/fs_operation.c | 4 +- fs/afs/fsclient.c | 108 +- fs/afs/inode.c | 7 +- fs/afs/internal.h | 59 +- fs/afs/rxrpc.c | 150 +-- fs/afs/write.c | 659 +++++------ fs/afs/yfsclient.c | 82 +- fs/cachefiles/Makefile | 1 + fs/cachefiles/interface.c | 5 +- fs/cachefiles/internal.h | 9 + fs/cachefiles/io.c | 403 +++++++ fs/fscache/Kconfig | 1 + fs/fscache/Makefile | 1 + fs/fscache/internal.h | 4 + fs/fscache/io.c | 116 ++ fs/fscache/page.c | 2 +- fs/fscache/stats.c | 1 + fs/netfs/Kconfig | 23 + fs/netfs/Makefile | 5 + fs/netfs/internal.h | 97 ++ fs/netfs/read_helper.c | 1180 +++++++++++++++++++ fs/netfs/stats.c | 59 + include/linux/fscache-cache.h | 4 + include/linux/fscache.h | 50 +- include/linux/netfs.h | 228 ++++ include/linux/pagemap.h | 22 + include/net/af_rxrpc.h | 2 +- include/trace/events/afs.h | 74 +- include/trace/events/netfs.h | 201 ++++ mm/filemap.c | 59 + mm/page-writeback.c | 25 + mm/readahead.c | 70 ++ net/rxrpc/recvmsg.c | 9 +- 40 files changed, 3888 insertions(+), 1070 deletions(-) create mode 100644 Documentation/filesystems/netfs_library.rst create mode 100644 fs/cachefiles/io.c create mode 100644 fs/fscache/io.c create mode 100644 fs/netfs/Kconfig create mode 100644 fs/netfs/Makefile create mode 100644 fs/netfs/internal.h create mode 100644 fs/netfs/read_helper.c create mode 100644 fs/netfs/stats.c create mode 100644 include/linux/netfs.h create mode 100644 include/trace/events/netfs.h