From patchwork Wed Jan 20 22:21:24 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 367919 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=-15.9 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 4BBCCC4321A for ; Thu, 21 Jan 2021 02:18:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F0D662388B for ; Thu, 21 Jan 2021 02:18:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391335AbhATXw0 (ORCPT ); Wed, 20 Jan 2021 18:52:26 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:28136 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731182AbhATWXI (ORCPT ); Wed, 20 Jan 2021 17:23:08 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611181296; 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=ZkCTUh6YIpz/AUkWavZvz8nrC1gxZflHJ+My0TUlYq8=; b=IWTlpI18BdGNb8bCQlxL3IJuhfPpWpOhdBZ4nzBJXW0h2O/JRnmiHZJ89kDlSZBgpbABSz fyo2o1kMWhVvbdgAeaQ2bTSbpFQHM4HDZm63wlce968NR2QuUO0pnPIAaTZE6doajpO6hC JQzP6EKgRL48tfenENZRF9BQQJqyF/Y= 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-468-4jyfIjAkMxSc_5pS-0UlJg-1; Wed, 20 Jan 2021 17:21:34 -0500 X-MC-Unique: 4jyfIjAkMxSc_5pS-0UlJg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CA4DD800D55; Wed, 20 Jan 2021 22:21:31 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-115-23.rdu2.redhat.com [10.10.115.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id 61F231992D; Wed, 20 Jan 2021 22:21:25 +0000 (UTC) Subject: [RFC][PATCH 00/25] Network fs helper library & fscache kiocb API From: David Howells To: Trond Myklebust , Anna Schumaker , Steve French , Dominique Martinet Cc: Takashi Iwai , Matthew Wilcox , linux-afs@lists.infradead.org, "Matthew Wilcox (Oracle)" , dhowells@redhat.com, Jeff Layton , David Wysochanski , Matthew Wilcox , 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: Wed, 20 Jan 2021 22:21:24 +0000 Message-ID: <161118128472.1232039.11746799833066425131.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: ceph-devel@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 four 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. 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. 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 David --- David Howells (24): iov_iter: Add ITER_XARRAY vm: Add wait/unlock functions for PG_fscache mm: Implement readahead_control pageset expansion vfs: Export rw_verify_area() for use by cachefiles netfs: Make a netfs helper module 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 Takashi Iwai (1): cachefiles: Drop superfluous readpages aops NULL check fs/Kconfig | 1 + fs/Makefile | 1 + fs/afs/Kconfig | 1 + fs/afs/dir.c | 225 ++++--- fs/afs/file.c | 472 ++++---------- fs/afs/fs_operation.c | 4 +- fs/afs/fsclient.c | 108 ++-- fs/afs/inode.c | 7 +- fs/afs/internal.h | 57 +- fs/afs/rxrpc.c | 150 ++--- fs/afs/write.c | 610 ++++++++++-------- fs/afs/yfsclient.c | 82 +-- fs/cachefiles/Makefile | 1 + fs/cachefiles/interface.c | 5 +- fs/cachefiles/internal.h | 9 + fs/cachefiles/rdwr.c | 2 - fs/cachefiles/rdwr2.c | 406 ++++++++++++ fs/fscache/Makefile | 3 +- fs/fscache/internal.h | 3 + fs/fscache/page.c | 2 +- fs/fscache/page2.c | 116 ++++ fs/fscache/stats.c | 1 + fs/internal.h | 5 - fs/netfs/Kconfig | 23 + fs/netfs/Makefile | 5 + fs/netfs/internal.h | 97 +++ fs/netfs/read_helper.c | 1142 +++++++++++++++++++++++++++++++++ fs/netfs/stats.c | 57 ++ fs/read_write.c | 1 + include/linux/fs.h | 1 + include/linux/fscache-cache.h | 4 + include/linux/fscache.h | 28 +- include/linux/netfs.h | 167 +++++ include/linux/pagemap.h | 16 + include/net/af_rxrpc.h | 2 +- include/trace/events/afs.h | 74 +-- include/trace/events/netfs.h | 201 ++++++ mm/filemap.c | 18 + mm/readahead.c | 70 ++ net/rxrpc/recvmsg.c | 9 +- 40 files changed, 3171 insertions(+), 1015 deletions(-) create mode 100644 fs/cachefiles/rdwr2.c create mode 100644 fs/fscache/page2.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