From patchwork Thu Dec 16 16:16:50 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 12681787 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 EC475C43219 for ; Thu, 16 Dec 2021 16:17:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239320AbhLPQRU (ORCPT ); Thu, 16 Dec 2021 11:17:20 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:35289 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239563AbhLPQRH (ORCPT ); Thu, 16 Dec 2021 11:17:07 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1639671426; 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=f3X0UCFiaEdO/ctmvb/WDPO6rzNjBrmRroZrBfAw3cE=; b=VXvyaKia+0tWXkirM2Mkw/kQqJmeNqqoQGzG6jJaXUZiirXJN7jVPN5ifYDC9+E86Zj+PG fIBVBsUb3hLWcTf4FN5hUo/kW0RLZrCxfXU1GzROBLFaTcQZRbGh5HOZ5Joy7xmh+vDaRX 10PR4jNsfB8dfVuYrnirvptNdA/UOLI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-344-RiCk6kitOg2JtKOGVO01Zg-1; Thu, 16 Dec 2021 11:17:02 -0500 X-MC-Unique: RiCk6kitOg2JtKOGVO01Zg-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 4A8735F9D7; Thu, 16 Dec 2021 16:16:54 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.122]) by smtp.corp.redhat.com (Postfix) with ESMTP id DA8D31037F42; Thu, 16 Dec 2021 16:16:50 +0000 (UTC) Organization: Red Hat UK Ltd. 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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH v3 38/68] vfs, cachefiles: Mark a backing file in use with an inode flag From: David Howells To: linux-cachefs@redhat.com Cc: dhowells@redhat.com, Trond Myklebust , Anna Schumaker , Steve French , Dominique Martinet , Jeff Layton , Matthew Wilcox , Alexander Viro , Omar Sandoval , JeffleXu , Linus Torvalds , 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: Thu, 16 Dec 2021 16:16:50 +0000 Message-ID: <163967141000.1823006.12920680657559677789.stgit@warthog.procyon.org.uk> In-Reply-To: <163967073889.1823006.12237147297060239168.stgit@warthog.procyon.org.uk> References: <163967073889.1823006.12237147297060239168.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Use an inode flag, S_KERNEL_FILE, to mark that a backing file is in use by the kernel to prevent cachefiles or other kernel services from interfering with that file. Alter rmdir to reject attempts to remove a directory marked with this flag. This is used by cachefiles to prevent cachefilesd from removing them. Using S_SWAPFILE instead isn't really viable as that has other effects in the I/O paths. Changes ======= ver #3: - Check for the object pointer being NULL in the tracepoints rather than the caller. Signed-off-by: David Howells cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/163819630256.215744.4815885535039369574.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906931596.143852.8642051223094013028.stgit@warthog.procyon.org.uk/ # v2 --- fs/cachefiles/Makefile | 1 + fs/cachefiles/namei.c | 43 +++++++++++++++++++++++++++++++++++++ fs/namei.c | 3 ++- include/linux/fs.h | 1 + include/trace/events/cachefiles.h | 42 ++++++++++++++++++++++++++++++++++++ 5 files changed, 89 insertions(+), 1 deletion(-) create mode 100644 fs/cachefiles/namei.c diff --git a/fs/cachefiles/Makefile b/fs/cachefiles/Makefile index 463e3d608b75..e0b092ca077f 100644 --- a/fs/cachefiles/Makefile +++ b/fs/cachefiles/Makefile @@ -7,6 +7,7 @@ cachefiles-y := \ cache.o \ daemon.o \ main.o \ + namei.o \ security.o cachefiles-$(CONFIG_CACHEFILES_ERROR_INJECTION) += error_inject.o diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c new file mode 100644 index 000000000000..913f83f1c900 --- /dev/null +++ b/fs/cachefiles/namei.c @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* CacheFiles path walking and related routines + * + * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include "internal.h" + +/* + * Mark the backing file as being a cache file if it's not already in use. The + * mark tells the culling request command that it's not allowed to cull the + * file or directory. The caller must hold the inode lock. + */ +static bool __cachefiles_mark_inode_in_use(struct cachefiles_object *object, + struct dentry *dentry) +{ + struct inode *inode = d_backing_inode(dentry); + bool can_use = false; + + if (!(inode->i_flags & S_KERNEL_FILE)) { + inode->i_flags |= S_KERNEL_FILE; + trace_cachefiles_mark_active(object, inode); + can_use = true; + } else { + pr_notice("cachefiles: Inode already in use: %pd\n", dentry); + } + + return can_use; +} + +/* + * Unmark a backing inode. The caller must hold the inode lock. + */ +static void __cachefiles_unmark_inode_in_use(struct cachefiles_object *object, + struct dentry *dentry) +{ + struct inode *inode = d_backing_inode(dentry); + + inode->i_flags &= ~S_KERNEL_FILE; + trace_cachefiles_mark_inactive(object, inode); +} diff --git a/fs/namei.c b/fs/namei.c index 1f9d2187c765..d81f04f8d818 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -3958,7 +3958,8 @@ int vfs_rmdir(struct user_namespace *mnt_userns, struct inode *dir, inode_lock(dentry->d_inode); error = -EBUSY; - if (is_local_mountpoint(dentry)) + if (is_local_mountpoint(dentry) || + (dentry->d_inode->i_flags & S_KERNEL_FILE)) goto out; error = security_inode_rmdir(dir, dentry); diff --git a/include/linux/fs.h b/include/linux/fs.h index 2c0b8e77d9ab..bcf1ca430139 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2249,6 +2249,7 @@ struct super_operations { #define S_ENCRYPTED (1 << 14) /* Encrypted file (using fs/crypto/) */ #define S_CASEFOLD (1 << 15) /* Casefolded file */ #define S_VERITY (1 << 16) /* Verity file (using fs/verity/) */ +#define S_KERNEL_FILE (1 << 17) /* File is in use by the kernel (eg. fs/cachefiles) */ /* * Note that nosuid etc flags are inode-specific: setting some file-system diff --git a/include/trace/events/cachefiles.h b/include/trace/events/cachefiles.h index 9bd5a8a60801..6331cd29880d 100644 --- a/include/trace/events/cachefiles.h +++ b/include/trace/events/cachefiles.h @@ -83,6 +83,48 @@ cachefiles_error_traces; #define E_(a, b) { a, b } +TRACE_EVENT(cachefiles_mark_active, + TP_PROTO(struct cachefiles_object *obj, + struct inode *inode), + + TP_ARGS(obj, inode), + + /* Note that obj may be NULL */ + TP_STRUCT__entry( + __field(unsigned int, obj ) + __field(ino_t, inode ) + ), + + TP_fast_assign( + __entry->obj = obj ? obj->debug_id : 0; + __entry->inode = inode->i_ino; + ), + + TP_printk("o=%08x i=%lx", + __entry->obj, __entry->inode) + ); + +TRACE_EVENT(cachefiles_mark_inactive, + TP_PROTO(struct cachefiles_object *obj, + struct inode *inode), + + TP_ARGS(obj, inode), + + /* Note that obj may be NULL */ + TP_STRUCT__entry( + __field(unsigned int, obj ) + __field(ino_t, inode ) + ), + + TP_fast_assign( + __entry->obj = obj ? obj->debug_id : 0; + __entry->inode = inode->i_ino; + ), + + TP_printk("o=%08x i=%lx", + __entry->obj, __entry->inode) + ); + TRACE_EVENT(cachefiles_vfs_error, TP_PROTO(struct cachefiles_object *obj, struct inode *backer, int error, enum cachefiles_error_trace where),