From patchwork Tue Apr 30 14:00:31 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 793399 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4B215168A9 for ; Tue, 30 Apr 2024 14:01:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714485670; cv=none; b=LM9C8DwTdlVtQ0WXFlk8imVxzrPPpW2oeGer9LZKWxIjEazvD9QFZLcW5ONREMH5xjqR/81EHaYZxxktDaZ+KTew3Hg3asXox9MTAGU6H06eibVK3fhF0riK3FSr9W/jkVhVJi8JS4o3qLW3IUR5pt6I6PS+VVh0aHBrEi6iS2M= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714485670; c=relaxed/simple; bh=NE+NGnp7qcYNIdSVHXWfKTzGPKGrqOKwMtnL1oSVkp0=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=iw44zp8cX1kAmI/TAVtaJ9/EdLgWwLjcza/UCdda9C2ivCeWap2v+dA5samZez6hxwm3dVfRoOgamVAHmWEUvdMknq3DxnyFuH5BgDTypYcKixv9gYeqn+D3Gs0aKNslqx1MzeFP/OpHPGZoN9Lro2ls0Z86dS/ZMWB8BwoJGq4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=KZAddHjR; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KZAddHjR" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1714485668; 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=K3Irydl6Xh7jL+cMJWxpcSfsWrNZFzC5/LPeqTp0XrU=; b=KZAddHjRG780fcaBzs1RBCGNA+ZahF40ltRDDLkt/ta5lOGGXBexN9eH2lJV4h2mHrHOqd ipXrLcqSoV5wrhxjjbTK3FW7j0AYYASnkR6lUMTr9IxPT1jx1g0SAYCwSu26zAGvexw7vf HUy+QlDeX+xxWdkYbiCmvIyp89Ub/HY= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-88-lzol3MtxNXm8_iyxwxlWwA-1; Tue, 30 Apr 2024 10:01:04 -0400 X-MC-Unique: lzol3MtxNXm8_iyxwxlWwA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id CD4D8802352; Tue, 30 Apr 2024 14:01:02 +0000 (UTC) Received: from warthog.procyon.org.com (unknown [10.42.28.22]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7D94C40C140B; Tue, 30 Apr 2024 14:00:59 +0000 (UTC) From: David Howells To: Christian Brauner , Jeff Layton , Gao Xiang , Dominique Martinet Cc: David Howells , Matthew Wilcox , Steve French , Marc Dionne , Paulo Alcantara , Shyam Prasad N , Tom Talpey , Eric Van Hensbergen , Ilya Dryomov , netfs@lists.linux.dev, linux-cachefs@redhat.com, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs@lists.linux.dev, linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 00/22] netfs, afs, 9p, cifs: Rework netfs to use ->writepages() to copy to cache Date: Tue, 30 Apr 2024 15:00:31 +0100 Message-ID: <20240430140056.261997-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: ceph-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 Hi Christian, Willy, Here's an updated version of my netfs writeback rewrite. There haven't been any major fixes. So far... The primary purpose of these patches is to rework the netfslib writeback implementation such that pages read from the cache are written to the cache through ->writepages(), thereby allowing the fscache page flag to be retired. The reworking also: (1) builds on top of the new writeback_iter() infrastructure; (2) makes it possible to use vectored write RPCs as discontiguous streams of pages can be accommodated; (3) makes it easier to do simultaneous content crypto and stream division. (4) provides support for retrying writes and re-dividing a stream; (5) replaces the ->launder_folio() op, so that ->writepages() is used instead; (6) uses mempools to allocate the netfs_io_request and netfs_io_subrequest structs to avoid allocation failure in the writeback path. Some code that uses the fscache page flag is retained for compatibility purposes with nfs and ceph. The code is switched to using the synonymous private_2 label instead and marked with deprecation comments. I have a separate set of patches that convert cifs to use this code. -~- In this new implementation, writeback_iter() is used to pump folios, progressively creating two parallel, but separate streams. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. (Note that more streams can be added if we have multiple servers to duplicate data to). Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple subrequests, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ Data that got read from the server that needs copying to the cache is stored in folios that are marked dirty and have folio->private set to a special value. The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. Collection is slightly complex as the collector has to work out where discontiguities happen in the folio list so that it doesn't try and collect folios that weren't included in the write out. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. The patches can be found here also: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=netfs-writeback David Link: https://lore.kernel.org/r/20240328163424.2781320-1-dhowells@redhat.com/ # v1 Changes ======= ver #2) - Rebase on v6.9-rc6 to accommodate some fixes that went upstream. - Make netfs_begin_writethrough() actually return an error. - Move the cifs invalidation patch to the cifs-netfs branch. - Mark writeback_iter() EXPORT_SYMBOL_GPL. - In p9_client_write_subreq(), use 'int len' rather than 'size_t len' because of the varargs packet formatter. - In netfs_perform_write(), don't wait for writeback if we don't need to. - Don't do the AFS StoreData RPC inline, but keep doing it from a workqueue. - Remove a couple of redundant checks where the second used to be inside a lock. - Add missing linux/bio.h for BIO_MAX_VECS in cachefiles. - Change a comma ending a statement to a semicolon. - Make filemap_invalidate_inode() take a range. - Make netfs_unbuffered_write_iter() use filemap_invalidate_inode(). David Howells (22): netfs: Update i_blocks when write committed to pagecache netfs: Replace PG_fscache by setting folio->private and marking dirty mm: Remove the PG_fscache alias for PG_private_2 netfs: Remove deprecated use of PG_private_2 as a second writeback flag netfs: Make netfs_io_request::subreq_counter an atomic_t netfs: Use subreq_counter to allocate subreq debug_index values mm: Provide a means of invalidation without using launder_folio 9p: Use alternative invalidation to using launder_folio afs: Use alternative invalidation to using launder_folio netfs: Remove ->launder_folio() support netfs: Use mempools for allocating requests and subrequests mm: Export writeback_iter() netfs: Switch to using unsigned long long rather than loff_t netfs: New writeback implementation netfs: Add some write-side stats and clean up some stat names netfs, afs: Implement helpers for new write code netfs, 9p: Implement helpers for new write code netfs, cachefiles: Implement helpers for new write code netfs: Cut over to using new writeback code netfs: Remove the old writeback code netfs: Miscellaneous tidy ups netfs, afs: Use writeback retry to deal with alternate keys fs/9p/vfs_addr.c | 60 +-- fs/afs/file.c | 8 +- fs/afs/internal.h | 6 +- fs/afs/validation.c | 4 +- fs/afs/write.c | 189 ++++---- fs/cachefiles/io.c | 76 +++- fs/ceph/addr.c | 24 +- fs/ceph/inode.c | 2 + fs/netfs/Makefile | 3 +- fs/netfs/buffered_read.c | 40 +- fs/netfs/buffered_write.c | 825 +++-------------------------------- fs/netfs/direct_write.c | 56 ++- fs/netfs/fscache_io.c | 14 +- fs/netfs/internal.h | 55 ++- fs/netfs/io.c | 155 +------ fs/netfs/main.c | 55 ++- fs/netfs/misc.c | 10 +- fs/netfs/objects.c | 81 +++- fs/netfs/output.c | 478 -------------------- fs/netfs/stats.c | 17 +- fs/netfs/write_collect.c | 808 ++++++++++++++++++++++++++++++++++ fs/netfs/write_issue.c | 675 ++++++++++++++++++++++++++++ fs/nfs/file.c | 8 +- fs/nfs/fscache.h | 6 +- fs/nfs/write.c | 4 +- fs/smb/client/file.c | 16 +- include/linux/fscache.h | 22 +- include/linux/netfs.h | 196 +++++---- include/linux/pagemap.h | 2 + include/net/9p/client.h | 2 + include/trace/events/netfs.h | 249 ++++++++++- mm/filemap.c | 60 ++- mm/page-writeback.c | 1 + net/9p/Kconfig | 1 + net/9p/client.c | 49 +++ 35 files changed, 2502 insertions(+), 1755 deletions(-) delete mode 100644 fs/netfs/output.c create mode 100644 fs/netfs/write_collect.c create mode 100644 fs/netfs/write_issue.c