From patchwork Mon Jul 13 16:30:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 11660359 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2B26F13A4 for ; Mon, 13 Jul 2020 16:31:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0AB5D2065F for ; Mon, 13 Jul 2020 16:31:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="girJxVKx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730457AbgGMQa4 (ORCPT ); Mon, 13 Jul 2020 12:30:56 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:47820 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730152AbgGMQa4 (ORCPT ); Mon, 13 Jul 2020 12:30:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1594657853; 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=NqgSBe1hMsdhej2UIP9RLhkmrdHOs9kRUk+TlrmQOJ4=; b=girJxVKxS86axr8y0B2PTOSjullcWCAwWhAOBTQt7JcmGSxKtiSwidG4O09/UDfPuFZwul Z123B/5d1BNJIBmcDGl4ZFx3otqQvPVEaRLB9zHyAdCJjQ6F3WsnRhFJuk1pQdW/9UBo/Y gOpS7Q+feREYlFwi4mC5YiuiHwZcunQ= 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-510-sdHPa1YUOVi8XOAOUOVUWA-1; Mon, 13 Jul 2020 12:30:49 -0400 X-MC-Unique: sdHPa1YUOVi8XOAOUOVUWA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D33EF805723; Mon, 13 Jul 2020 16:30:46 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-112-113.rdu2.redhat.com [10.10.112.113]) by smtp.corp.redhat.com (Postfix) with ESMTP id 31AB81002391; Mon, 13 Jul 2020 16:30:41 +0000 (UTC) Subject: [PATCH 00/32] fscache: Rewrite 2: Make the I/O interface use kiocb/iov_iter From: David Howells To: Trond Myklebust , Anna Schumaker , Steve French , Alexander Viro , Matthew Wilcox Cc: Jeff Layton , Dave Wysochanski , dhowells@redhat.com, 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: Mon, 13 Jul 2020 17:30:40 +0100 Message-ID: <159465784033.1376674.18106463693989811037.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.22 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: ceph-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org Here's a set of patches that massively overhauls the object lifecycle management and the I/O API of the local caching for network filesystems code for a reduction of about 3000 LoC and a 1000 line Documentation reduction. The ability to use async DIO to pass data to/from the cache gives a huge speed bonus and uses less memory. So far, only AFS has been ported to use this. This series disabled fscache support in all other filesystems that use it. I'm working on NFS, but it's tricky and I could use some help. 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. 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. - struct fscache_io_request - fscache_read() and fscache_write(). (2) The cache may require that the I/O fulfil certain alignment and length granularity constraints. This, and whether the cache contains the desired data, can be queried. - struct fscache_request_shape - fscache_shape_request() (3) 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() (4) 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() (5) A helper API for reads is provided to combine the (1), (2) above and read_cache_pages() and also 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(), ->readpages() and prefetching for ->write_begin(). - struct fscache_io_request - fscache_read_helper() 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_MAPPING, that iterates over the specified byte range of a mapping. 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). It may make sense to make this more generic and just take an xarray that is known to be laden with pages. The one tricky bit there is that the iteration routines call find_get_page_contig() - though the only thing the mapping is used for is to find the xarray containing the pages. 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. So, to be done hopefully before the next merge window: (1) Need to investigate whether I need to be lazy, but only to an extent, about closing up backing files. (2) Make NFS, CIFS, Ceph, 9P work with it. Jeff Layton is working on Ceph and Dave Wysochanski is working on NFS. And beyond that: (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. 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 (1): cachefiles: Shape write requests fs/9p/Kconfig | 2 +- fs/Makefile | 2 +- fs/afs/Kconfig | 1 + fs/afs/cache.c | 54 -- fs/afs/cell.c | 9 +- fs/afs/dir.c | 242 +++++-- fs/afs/file.c | 575 +++++++-------- fs/afs/fs_operation.c | 4 +- fs/afs/fsclient.c | 154 ++-- fs/afs/inode.c | 57 +- fs/afs/internal.h | 58 +- fs/afs/rxrpc.c | 150 ++-- fs/afs/volume.c | 9 +- fs/afs/write.c | 413 +++++++---- fs/afs/yfsclient.c | 113 ++- fs/cachefiles/Makefile | 3 +- fs/cachefiles/bind.c | 11 +- fs/cachefiles/content-map.c | 476 ++++++++++++ fs/cachefiles/daemon.c | 10 +- fs/cachefiles/interface.c | 564 ++++++++------- fs/cachefiles/internal.h | 139 ++-- fs/cachefiles/io.c | 279 +++++++ fs/cachefiles/main.c | 12 +- fs/cachefiles/namei.c | 508 +++++-------- fs/cachefiles/rdwr.c | 974 ------------------------- fs/cachefiles/xattr.c | 263 +++---- fs/ceph/Kconfig | 2 +- fs/cifs/Kconfig | 2 +- fs/fscache/Kconfig | 8 + fs/fscache/Makefile | 10 +- fs/fscache/cache.c | 136 ++-- fs/fscache/cookie.c | 769 ++++++++------------ fs/fscache/dispatcher.c | 150 ++++ fs/fscache/fsdef.c | 56 +- fs/fscache/histogram.c | 2 +- fs/fscache/internal.h | 260 +++---- fs/fscache/io.c | 201 +++++ fs/fscache/main.c | 35 +- fs/fscache/netfs.c | 10 +- fs/fscache/obj.c | 345 +++++++++ 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 | 13 +- fs/fscache/read_helper.c | 688 ++++++++++++++++++ fs/fscache/stats.c | 265 +++---- fs/internal.h | 5 - fs/nfs/Kconfig | 2 +- fs/nfs/fscache-index.c | 4 +- fs/read_write.c | 1 + include/linux/fs.h | 2 + include/linux/fscache-cache.h | 508 +++---------- include/linux/fscache-obsolete.h | 13 + include/linux/fscache.h | 814 ++++++++------------- include/linux/mm.h | 1 + include/linux/pagemap.h | 14 + include/linux/uio.h | 11 + include/net/af_rxrpc.h | 2 +- include/trace/events/afs.h | 51 +- include/trace/events/cachefiles.h | 285 ++++++-- include/trace/events/fscache.h | 421 ++--------- include/trace/events/fscache_support.h | 91 +++ lib/iov_iter.c | 286 +++++++- mm/filemap.c | 27 +- net/rxrpc/recvmsg.c | 9 +- 67 files changed, 5598 insertions(+), 8246 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/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/fscache/read_helper.c create mode 100644 include/linux/fscache-obsolete.h create mode 100644 include/trace/events/fscache_support.h