From patchwork Fri Nov 20 15:02:32 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 329232 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=-15.8 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 AFCF5C63777 for ; Fri, 20 Nov 2020 15:03:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 478EC22226 for ; Fri, 20 Nov 2020 15:03:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="eZtFKr4w" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728292AbgKTPCz (ORCPT ); Fri, 20 Nov 2020 10:02:55 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:59122 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727808AbgKTPCz (ORCPT ); Fri, 20 Nov 2020 10:02:55 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605884572; 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=AvzEbXkWDGq3m4j2v0MYXHV0NRfK51mv7g+MgzcU+jk=; b=eZtFKr4wvT6qLjocaSt4JfIlqdqzjiTYXKeqSnuFtpgWNOdCcMZ3njIhuf9AFZ4dTZIiR+ Irn4b0w6UZyKVzdAcTfh5Y4rV42kIU7LQpfwyMFN3RCkD6tOOGFq3iNHoc9QwtcGrqWwN4 agnkg5OofL7NoUv03VGj9fExB3Y8Q78= 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-328-i1aNzOicOSyMzP5ogeYp2g-1; Fri, 20 Nov 2020 10:02:44 -0500 X-MC-Unique: i1aNzOicOSyMzP5ogeYp2g-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3C1B263CC2; Fri, 20 Nov 2020 15:02:41 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-112-246.rdu2.redhat.com [10.10.112.246]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6061660C05; Fri, 20 Nov 2020 15:02:33 +0000 (UTC) Subject: [RFC PATCH 00/76] fscache: Modernisation From: David Howells To: Trond Myklebust , Anna Schumaker , Steve French , Dominique Martinet Cc: linux-cifs@vger.kernel.org, linux-afs@lists.infradead.org, v9fs-developer@lists.sourceforge.net, "Matthew Wilcox (Oracle)" , Dave Wysochanski , Jeff Layton , Trond Myklebust , Ilya Dryomov , ceph-devel@vger.kernel.org, Latchesar Ionkov , Matthew Wilcox , linux-nfs@vger.kernel.org, Eric Van Hensbergen , dhowells@redhat.com, Jeff Layton , 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: Fri, 20 Nov 2020 15:02:32 +0000 Message-ID: <160588455242.3465195.3214733858273019178.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org Here's a set of patches that modernises the fscache API by switching to use the kiocb interface to do async DIO to/from the cache rather than by snooping the pagecache of the backing filesystem - something that doesn't seem totally reliable. This means that the cache uses a lot less memory than it did and is faster than it was. A netfs helper library is provided that handles most of the readpage, readahead and write_begin ops on behalf of the filesystem. This is intended to be used unconditionally by the filesystem and provides a common framework for doing caching, transparent huge pages (which works with AFS) and, in the future, possibly fscrypt. 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. This patch series ports the AFS filesystem to the new API and disables caching in NFS, Ceph, CIFS and 9P. Jeff Layton has a port for Ceph that is solid and Dave Wysochanski has one for NFS that is mostly solid. I've given partial ports to 9P and CIFS to Dominique Martinet and Steve French respectively. -~- To this end, the fscache API has been massively overhauled. Code that was using the old API is now disabled. It's not practical to have the two APIs coexist because they have totally different ways of doing things, but must share common data. The following parts have been removed: - The object state machine - The I/O operation manager - All non-transient references from fscache to the netfs's data - All non-transient callbacks from fscache to the netfs - The backing page I/O monitoring - The tracking of netfs pages that fscache knows about - The tracking of netfs pages that need writing to the cache - The use of bmap to work out if a page is stored in the cache - The copy of data to/from backing pages to netfs pages. Instead, the I/O to the cache is driven much more from the netfs and the netfs helpers. There are a number of aspects to the I/O API: (1) The lowest level I/O primitives just take an iov_iter and start async DIO on the cache objects. The caller gets a callback upon completion. The PG_fscache bit is now just used to indicate that there's a write to the cache in progress. The cache will keep track in xattrs as to what areas of the backing file are occupied. - fscache_begin_operation(), fscache_end_operation() - fscache_read() and fscache_write(). (2) The cookie that's obtained when an inode is set up must be 'used' when a file is opened (with an indication as to whether it might be modified) and 'unused' when it is done with. At the point of unuse, the auxdata and file size can be specified. - fscache_use_cookie(), fscache_unuse_cookie() (3) The cookie can be invalidated at any time, and new auxiliary data and a new size provided. Any in-progress I/O will either cause new I/O to wait, or a replacement tmpfile will be created and the in-progress I/O will just be abandoned. The on-disk auxdata (in xattrs, say) are updated lazily. - fscache_invalidate() (4) The netfs helpers for read are provided to combine the (1), (2) above and do read-(re)issue to the network in the case that the data isn't present or the cache fails. This requires that an operation descriptor be allocated and given some operations. This needs to be used for ->readpage(), ->readahead() and prefetching for ->write_begin(). ->readpages() is obsolete and soon to go away. - include/linux/netfs.h - netfs_readpage(), netfs_readahead(), netfs_begin_write() (5) There are some helpers to keep a cookie in use once a file has been closed so that writeback can write to the cache. write_inode and evict inode need to clear this. - fscache_set_page_dirty(), fscache_unpin_writeback() - fscache_write_to_cache() I've also simplified the cookie management API to remove struct fscache_cookie_def. Instead, the pertinent details are supplied when a cookie is created and the file size, key and auxdata are stored in the cookie. Callbacks and backpointers are simply removed. I've added some pieces outside of the API also: (1) An inode flag to mark a backing cachefile as being in use by the kernel. This prevents multiple caches mounted in the same directory from fighting over the same files. It can also be extended to exclude other kernel users (such as swap) and could also be used to prevent userspace interfering with the file. (2) A new I/O iterator class, ITER_XARRAY, that iterates over the specified byte range of an xarray. The caller is required to make sure that the pages don't evaporate under the callee (eg. pinning them by PG_locked, PG_writeback, PG_fscache or usage count). This is better than an ITER_BVEC as no allocation of bio_vec structs is required since the xarray holds pointers to all the pages involved. (3) Wait and unlock functions for PG_fscache. These are in the core, so no need to call into fscache for it. Future stuff: (1) Avoid the need to double-truncate a backing file on relinquishment. The first truncate cuts of rubbish data from the end so that it's not retrieved in future; the second expands the EOF back out to DIO block size. (2) Add a write helper to improve on generic_perform_write(), allowing a span of pages to be modified as a block and to take account of cache granularity. (3) Put in support for versioned monolithic objects (eg. AFS directories). (4) Currently it cachefiles only caches large files up to 1GiB. File data beyond that isn't cached. The problem here is that I'm using an xattr to hold the content map, and xattrs may be limited in size and I've limited myself to using a 512 byte xattr. I can easily make it cache a non-sparse file of any size with no map, but as soon as it becomes sparse, I need a different strategy. (5) Change the indexing strategy so that the culling mechanism is brought into the kernel, rather than doing that in userspace, and use an index table of files with a LRU list. (6) Add support for throttling readahead when the server pushes back (cifs credits). These patches can be found also on: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=fscache-iter David --- David Howells (75): nfs, cifs, ceph, 9p: Disable use of fscache prior to its rewrite afs: Disable use of the fscache I/O routines fscache: Add a cookie debug ID and use that in traces fscache: Procfile to display cookies fscache: Remove the old I/O API fscache: Remove the netfs data from the cookie fscache: Remove struct fscache_cookie_def fscache: Remove store_limit* from struct fscache_object fscache: Remove fscache_check_consistency() fscache: Remove fscache_attr_changed() fscache: Remove obsolete stats fscache: Remove old I/O tracepoints fscache: Temporarily disable fscache_invalidate() fscache: Remove the I/O operation manager fscache: Change %p in format strings to something else cachefiles: Change %p in format strings to something else iov_iter: Add ITER_XARRAY vm: Add wait/unlock functions for PG_fscache mm: Implement readahead_control pageset expansion mm: Stop generic_file_buffered_read() from grabbing a superfluous page vfs: Export rw_verify_area() for use by cachefiles vfs: Provide S_CACHE_FILE inode flag cachefiles: Remove tree of active files and use S_CACHE_FILE inode flag fscache: Provide a simple thread pool for running ops asynchronously fscache: Replace the object management state machine fscache: Rewrite the I/O API based on iov_iter fscache: Keep track of size of a file last set independently on the server fscache, cachefiles: Fix disabled histogram warnings fscache: Recast assertion in terms of cookie not being an index vfs, fscache: Force ->write_inode() to occur if cookie pinned for writeback fscache: Allow ->put_super() to be used to wait for cache operations netfs: Make a netfs helper module netfs: Provide readahead and readpage netfs helpers netfs: Use the cache fscache: read-helper: Add tracepoints cachefiles: Remove some redundant checks on unsigned values cachefiles: trace: Log coherency checks cachefiles: Split cachefiles_drop_object() up a bit cachefiles: Implement new fscache I/O backend API cachefiles: Merge object->backer into object->dentry cachefiles: Implement a content-present indicator and bitmap cachefiles: Shape requests from the fscache read helper cachefiles: Round the cachefile size up to DIO block size cachefiles: Implement read and write parts of new I/O API cachefiles: Add I/O tracepoints fscache: Display cache-specific data in /proc/fs/fscache/objects fscache: Remove more obsolete stats fscache: Always create /proc/fs/fscache/stats if configured netfs: Stats fscache: New stats fscache, cachefiles: Rewrite invalidation fscache: Implement "will_modify" parameter on fscache_use_cookie() fscache: Provide resize operation fscache: Remove the update operation 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 netfs: Add write_begin helper fscache: Add support for writing to the cache afs: Use the fscache_write_begin() helper afs: Copy local writes to the cache when writing to the server afs: Invoke fscache_resize_cookie() when handling ATTR_SIZE for setattr afs: Add O_DIRECT read support afs: Skip truncation on the server of data we haven't written yet afs: Make afs_write_begin() return the THP subpage afs: Fix speculative status fetch going out of order wrt to modifications Jeff Layton (1): fscache: disable cookie when doing an invalidation for DIO write fs/Kconfig | 1 + fs/Makefile | 1 + fs/afs/Kconfig | 1 + fs/afs/cache.c | 54 -- fs/afs/cell.c | 9 +- fs/afs/dir.c | 226 ++++-- fs/afs/file.c | 562 +++++-------- fs/afs/fs_operation.c | 4 +- fs/afs/fsclient.c | 126 ++- fs/afs/inode.c | 108 ++- fs/afs/internal.h | 69 +- fs/afs/rxrpc.c | 150 ++-- fs/afs/super.c | 25 + fs/afs/volume.c | 9 +- fs/afs/write.c | 819 +++++++++++-------- fs/afs/yfsclient.c | 94 +-- fs/cachefiles/Makefile | 3 +- fs/cachefiles/bind.c | 13 +- fs/cachefiles/content-map.c | 515 ++++++++++++ fs/cachefiles/daemon.c | 10 +- fs/cachefiles/interface.c | 597 ++++++++------ fs/cachefiles/internal.h | 155 ++-- fs/cachefiles/io.c | 360 +++++++++ fs/cachefiles/key.c | 2 +- fs/cachefiles/main.c | 12 +- fs/cachefiles/namei.c | 538 +++++-------- fs/cachefiles/rdwr.c | 975 ---------------------- fs/cachefiles/xattr.c | 271 +++---- fs/fs-writeback.c | 8 + fs/fscache/Kconfig | 2 + fs/fscache/Makefile | 10 +- fs/fscache/cache.c | 171 ++-- fs/fscache/cache_init.c | 139 ++++ fs/fscache/cookie.c | 939 ++++++++++------------ fs/fscache/dispatcher.c | 151 ++++ fs/fscache/fsdef.c | 56 +- fs/fscache/histogram.c | 2 +- fs/fscache/internal.h | 268 ++----- fs/fscache/io.c | 390 +++++++++ fs/fscache/main.c | 151 +--- fs/fscache/netfs.c | 10 +- fs/fscache/obj.c | 360 +++++++++ fs/fscache/object-list.c | 129 +-- fs/fscache/object.c | 1133 -------------------------- fs/fscache/object_bits.c | 120 +++ fs/fscache/operation.c | 633 --------------- fs/fscache/page.c | 1248 ----------------------------- fs/fscache/proc.c | 55 +- fs/fscache/stats.c | 233 ++---- fs/internal.h | 5 - fs/netfs/Kconfig | 23 + fs/netfs/Makefile | 5 + fs/netfs/internal.h | 97 +++ fs/netfs/read_helper.c | 1125 ++++++++++++++++++++++++++ fs/netfs/stats.c | 57 ++ fs/nfs/fscache-index.c | 4 +- fs/read_write.c | 1 + include/linux/fs.h | 5 + include/linux/fscache-cache.h | 510 +++--------- include/linux/fscache-obsolete.h | 13 + include/linux/fscache.h | 814 ++++++++----------- include/linux/netfs.h | 111 +++ include/linux/pagemap.h | 16 + include/linux/uio.h | 11 + include/linux/writeback.h | 1 + include/net/af_rxrpc.h | 2 +- include/trace/events/afs.h | 74 +- include/trace/events/cachefiles.h | 287 +++++-- include/trace/events/fscache.h | 428 ++-------- include/trace/events/netfs.h | 202 +++++ lib/iov_iter.c | 312 +++++++- mm/filemap.c | 20 + mm/readahead.c | 70 ++ net/rxrpc/recvmsg.c | 9 +- 74 files changed, 7421 insertions(+), 8698 deletions(-) create mode 100644 fs/cachefiles/content-map.c create mode 100644 fs/cachefiles/io.c delete mode 100644 fs/cachefiles/rdwr.c create mode 100644 fs/fscache/cache_init.c create mode 100644 fs/fscache/dispatcher.c create mode 100644 fs/fscache/io.c create mode 100644 fs/fscache/obj.c delete mode 100644 fs/fscache/object.c create mode 100644 fs/fscache/object_bits.c delete mode 100644 fs/fscache/operation.c delete mode 100644 fs/fscache/page.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/fscache-obsolete.h create mode 100644 include/linux/netfs.h create mode 100644 include/trace/events/netfs.h