From patchwork Thu Dec 22 15:02:11 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 13080077 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 51DEEC4332F for ; Thu, 22 Dec 2022 15:03:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235877AbiLVPDx (ORCPT ); Thu, 22 Dec 2022 10:03:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50266 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235778AbiLVPDh (ORCPT ); Thu, 22 Dec 2022 10:03:37 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8D5F826483 for ; Thu, 22 Dec 2022 07:02:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1671721349; 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: in-reply-to:in-reply-to:references:references; bh=GGA96kB5DfYk4dcqOCNOCnjdGba2ksAIa634gghn6lw=; b=b28qw1iLa4YJxjFPD8RcElvPLWsMt4IWZy+83FjonqLNtIV2Do1yEa2Ech+q3OV/RuISVu F79Rt55V0m5CRg24ZpQ4ScFGq0Ppf4SLCtdnMrHRl3MmvsPy028JugUHgFk5fqlX66Z4/r YkisfynyZSd6cHQbEag2+fUTDUkDMgI= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-391-KQGAhYXSPRu5DHU9hS8EeA-1; Thu, 22 Dec 2022 10:02:25 -0500 X-MC-Unique: KQGAhYXSPRu5DHU9hS8EeA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7581E3C0F683; Thu, 22 Dec 2022 15:02:24 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.96]) by smtp.corp.redhat.com (Postfix) with ESMTP id E186814152F4; Thu, 22 Dec 2022 15:02:11 +0000 (UTC) Organization: Red Hat UK Ltd. 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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH v5 2/3] mm, netfs, fscache: Stop read optimisation when folio removed from pagecache From: David Howells To: Matthew Wilcox Cc: Rohith Surabattula , Linus Torvalds , Steve French , Shyam Prasad N , Rohith Surabattula , Dave Wysochanski , Dominique Martinet , Ilya Dryomov , linux-cachefs@redhat.com, linux-cifs@vger.kernel.org, linux-afs@lists.infradead.org, v9fs-developer@lists.sourceforge.net, ceph-devel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, dhowells@redhat.com, Linus Torvalds , Jeff Layton , 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-erofs@lists.ozlabs.org, linux-ext4@lists.ozlabs.org, linux-cachefs@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Thu, 22 Dec 2022 15:02:11 +0000 Message-ID: <167172133121.2334525.2608800018126833569.stgit@warthog.procyon.org.uk> In-Reply-To: <167172131368.2334525.8569808925687731937.stgit@warthog.procyon.org.uk> References: <167172131368.2334525.8569808925687731937.stgit@warthog.procyon.org.uk> User-Agent: StGit/1.5 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org Fscache has an optimisation by which reads from the cache are skipped until we know that (a) there's data there to be read and (b) that data isn't entirely covered by pages resident in the netfs pagecache. This is done with two flags manipulated by fscache_note_page_release(): if (... test_bit(FSCACHE_COOKIE_HAVE_DATA, &cookie->flags) && test_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags)) clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags); where the NO_DATA_TO_READ flag causes cachefiles_prepare_read() to indicate that netfslib should download from the server or clear the page instead. The fscache_note_page_release() function is intended to be called from ->releasepage() - but that only gets called if PG_private or PG_private_2 is set - and currently the former is at the discretion of the network filesystem and the latter is only set whilst a page is being written to the cache, so sometimes we miss clearing the optimisation. Fix this by following Willy's suggestion[1] and adding an address_space flag, AS_RELEASE_ALWAYS, that causes filemap_release_folio() to always call ->release_folio() if it's set, even if PG_private or PG_private_2 aren't set. Note that this would require folio_test_private() and page_has_private() to become more complicated. To avoid that, in the places[*] where these are used to conditionalise calls to filemap_release_folio() and try_to_release_page(), the tests are removed the those functions just jumped to unconditionally and the test is performed there. [*] There are some exceptions in vmscan.c where the check guards more than just a call to the releaser. I've added a function, folio_needs_release() to wrap all the checks for that. AS_RELEASE_ALWAYS should be set if a non-NULL cookie is obtained from fscache and cleared in ->evict_inode() before truncate_inode_pages_final() is called. Additionally, the FSCACHE_COOKIE_NO_DATA_TO_READ flag needs to be cleared and the optimisation cancelled if a cachefiles object already contains data when we open it. Changes: ======== ver #4) - Split out merging of folio_has_private()/filemap_release_folio() call pairs into a preceding patch. - Don't need to clear AS_RELEASE_ALWAYS in ->evict_inode(). ver #3) - Fixed mapping_clear_release_always() to use clear_bit() not set_bit(). - Moved a '&&' to the correct line. ver #2) - Rewrote entirely according to Willy's suggestion[1]. Reported-by: Rohith Surabattula Suggested-by: Matthew Wilcox Signed-off-by: David Howells cc: Matthew Wilcox cc: Linus Torvalds cc: Steve French cc: Shyam Prasad N cc: Rohith Surabattula cc: Dave Wysochanski cc: Dominique Martinet cc: Ilya Dryomov cc: linux-cachefs@redhat.com cc: linux-cifs@vger.kernel.org cc: linux-afs@lists.infradead.org cc: v9fs-developer@lists.sourceforge.net cc: ceph-devel@vger.kernel.org cc: linux-nfs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org Link: https://lore.kernel.org/r/Yk9V/03wgdYi65Lb@casper.infradead.org/ [1] Link: https://lore.kernel.org/r/164928630577.457102.8519251179327601178.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/166844174069.1124521.10890506360974169994.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/166869495238.3720468.4878151409085146764.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/1459152.1669208550@warthog.procyon.org.uk/ # v3 also Link: https://lore.kernel.org/r/166924372614.1772793.3804564782036202222.stgit@warthog.procyon.org.uk/ # v4 --- fs/9p/cache.c | 2 ++ fs/afs/internal.h | 2 ++ fs/cachefiles/namei.c | 2 ++ fs/ceph/cache.c | 2 ++ fs/cifs/fscache.c | 2 ++ include/linux/pagemap.h | 16 ++++++++++++++++ mm/internal.h | 5 ++++- 7 files changed, 30 insertions(+), 1 deletion(-) diff --git a/fs/9p/cache.c b/fs/9p/cache.c index cebba4eaa0b5..12c0ae29f185 100644 --- a/fs/9p/cache.c +++ b/fs/9p/cache.c @@ -68,6 +68,8 @@ void v9fs_cache_inode_get_cookie(struct inode *inode) &path, sizeof(path), &version, sizeof(version), i_size_read(&v9inode->netfs.inode)); + if (v9inode->netfs.cache) + mapping_set_release_always(inode->i_mapping); p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n", inode, v9fs_inode_cookie(v9inode)); diff --git a/fs/afs/internal.h b/fs/afs/internal.h index 9ba7b68375c9..8e4afaeb6bff 100644 --- a/fs/afs/internal.h +++ b/fs/afs/internal.h @@ -680,6 +680,8 @@ static inline void afs_vnode_set_cache(struct afs_vnode *vnode, { #ifdef CONFIG_AFS_FSCACHE vnode->netfs.cache = cookie; + if (cookie) + mapping_set_release_always(vnode->netfs.inode.i_mapping); #endif } diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c index 03ca8f2f657a..50b2ee163af6 100644 --- a/fs/cachefiles/namei.c +++ b/fs/cachefiles/namei.c @@ -584,6 +584,8 @@ static bool cachefiles_open_file(struct cachefiles_object *object, if (ret < 0) goto check_failed; + clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &object->cookie->flags); + object->file = file; /* Always update the atime on an object we've just looked up (this is diff --git a/fs/ceph/cache.c b/fs/ceph/cache.c index 177d8e8d73fe..de1dee46d3df 100644 --- a/fs/ceph/cache.c +++ b/fs/ceph/cache.c @@ -36,6 +36,8 @@ void ceph_fscache_register_inode_cookie(struct inode *inode) &ci->i_vino, sizeof(ci->i_vino), &ci->i_version, sizeof(ci->i_version), i_size_read(inode)); + if (ci->netfs.cache) + mapping_set_release_always(inode->i_mapping); } void ceph_fscache_unregister_inode_cookie(struct ceph_inode_info *ci) diff --git a/fs/cifs/fscache.c b/fs/cifs/fscache.c index f6f3a6b75601..79e9665dfc90 100644 --- a/fs/cifs/fscache.c +++ b/fs/cifs/fscache.c @@ -108,6 +108,8 @@ void cifs_fscache_get_inode_cookie(struct inode *inode) &cifsi->uniqueid, sizeof(cifsi->uniqueid), &cd, sizeof(cd), i_size_read(&cifsi->netfs.inode)); + if (cifsi->netfs.cache) + mapping_set_release_always(inode->i_mapping); } void cifs_fscache_unuse_inode_cookie(struct inode *inode, bool update) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 29e1f9e76eb6..a0d433e0addd 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -199,6 +199,7 @@ enum mapping_flags { /* writeback related tags are not used */ AS_NO_WRITEBACK_TAGS = 5, AS_LARGE_FOLIO_SUPPORT = 6, + AS_RELEASE_ALWAYS, /* Call ->release_folio(), even if no private data */ }; /** @@ -269,6 +270,21 @@ static inline int mapping_use_writeback_tags(struct address_space *mapping) return !test_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags); } +static inline bool mapping_release_always(const struct address_space *mapping) +{ + return test_bit(AS_RELEASE_ALWAYS, &mapping->flags); +} + +static inline void mapping_set_release_always(struct address_space *mapping) +{ + set_bit(AS_RELEASE_ALWAYS, &mapping->flags); +} + +static inline void mapping_clear_release_always(struct address_space *mapping) +{ + clear_bit(AS_RELEASE_ALWAYS, &mapping->flags); +} + static inline gfp_t mapping_gfp_mask(struct address_space * mapping) { return mapping->gfp_mask; diff --git a/mm/internal.h b/mm/internal.h index c4c8e58e1d12..5421ce8661fa 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -168,7 +168,10 @@ static inline void set_page_refcounted(struct page *page) */ static inline bool folio_needs_release(struct folio *folio) { - return folio_has_private(folio); + struct address_space *mapping = folio->mapping; + + return folio_has_private(folio) || + (mapping && mapping_release_always(mapping)); } extern unsigned long highest_memmap_pfn;