From patchwork Thu Jul 7 12:32:04 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Namjae Jeon X-Patchwork-Id: 12909430 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 E374BC433EF for ; Thu, 7 Jul 2022 12:32:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235519AbiGGMcp (ORCPT ); Thu, 7 Jul 2022 08:32:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33184 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235514AbiGGMco (ORCPT ); Thu, 7 Jul 2022 08:32:44 -0400 Received: from mail-pf1-f170.google.com (mail-pf1-f170.google.com [209.85.210.170]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E99011AF05; Thu, 7 Jul 2022 05:32:42 -0700 (PDT) Received: by mail-pf1-f170.google.com with SMTP id b9so3046952pfp.10; Thu, 07 Jul 2022 05:32:42 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=DfATGYwCmyMFnyO+58XP90DTmpkbLHag6MGE/8UHnfY=; b=YkoEEecKa3m/9J8pn2K1O0cGkHGu6iTHHYv5TWNSnDTBGGDv0Qn6lwq3Aj0YjCzXsj yJsgz05oshUWVZjxkrNPhRBUWy91a29epzoMD83Fjo6fH8kgM+kOrF10FSHXz64Luaiz 3zqoFJkxOE/p2Cj/ZRMzKpeh9Rcg5qmB7qQXV+UcBd2ji/nYRKGzD0XsOZOC3ohnxVGU T0SHcPClk8Y3jBsUi8xQF5owpCWw3Orr7uC5p38yo7pCsmvTnhz9FAwza82WFcR1URYP Bbz6MN5W+T6nnZ9xJ814b+ThKZaSxfLCbRNgNhoxTJIVlTHkfB/iC7J7jTANLtSYTMho /bjQ== X-Gm-Message-State: AJIora8aJ2O9MfDnBntwK7cnhWc1X15pp+oPU/e7lglZtCiw7/YZzaWm Bcesfp7tmC5NkmbdeIMAY5w= X-Google-Smtp-Source: AGRyM1uP/JEiZgZrEeylNesutm/ZWDJo6MdLZUifEHcq0xUl6fkoSEw5Ry2IVLe14BTXEh4ghDO2pQ== X-Received: by 2002:a17:90a:404a:b0:1ea:e936:b69 with SMTP id k10-20020a17090a404a00b001eae9360b69mr4842717pjg.133.1657197162426; Thu, 07 Jul 2022 05:32:42 -0700 (PDT) Received: from localhost.localdomain ([211.49.23.9]) by smtp.gmail.com with ESMTPSA id u13-20020a63454d000000b0040d2224ae04sm25825227pgk.76.2022.07.07.05.32.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Jul 2022 05:32:41 -0700 (PDT) From: Namjae Jeon To: viro@zeniv.linux.org.uk Cc: linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org, smfrench@gmail.com, hyc.lee@gmail.com, senozhatsky@chromium.org, Namjae Jeon Subject: [PATCH v6 2/3] fs: introduce lock_rename_child() helper Date: Thu, 7 Jul 2022 21:32:04 +0900 Message-Id: <20220707123205.6902-3-linkinjeon@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220707123205.6902-1-linkinjeon@kernel.org> References: <20220707123205.6902-1-linkinjeon@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Al Viro Pass the dentry of a source file and the dentry of a destination directory to lock parent inodes for rename. As soon as this function returns, ->d_parent of the source file dentry is stable and inodes are properly locked for calling vfs-rename. This helper is needed for ksmbd server. rename request of SMB protocol has to rename an opened file, no matter which directory it's in. Signed-off-by: Al Viro Signed-off-by: Namjae Jeon --- fs/namei.c | 46 ++++++++++++++++++++++++++++++++----------- include/linux/namei.h | 1 + 2 files changed, 36 insertions(+), 11 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 1f28d3f463c3..c22bdef164ca 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2998,20 +2998,10 @@ static inline int may_create(struct user_namespace *mnt_userns, return inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC); } -/* - * p1 and p2 should be directories on the same fs. - */ -struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) +static struct dentry *lock_two_directories(struct dentry *p1, struct dentry *p2) { struct dentry *p; - if (p1 == p2) { - inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); - return NULL; - } - - mutex_lock(&p1->d_sb->s_vfs_rename_mutex); - p = d_ancestor(p2, p1); if (p) { inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); @@ -3030,8 +3020,42 @@ struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); return NULL; } + +/* + * p1 and p2 should be directories on the same fs. + */ +struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) +{ + if (p1 == p2) { + inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); + return NULL; + } + + mutex_lock(&p1->d_sb->s_vfs_rename_mutex); + return lock_two_directories(p1, p2); +} EXPORT_SYMBOL(lock_rename); +struct dentry *lock_rename_child(struct dentry *c1, struct dentry *p2) +{ + if (READ_ONCE(c1->d_parent) == p2) { + inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); + if (likely(c1->d_parent == p2)) + return NULL; + + inode_unlock(p2->d_inode); + } + + mutex_lock(&c1->d_sb->s_vfs_rename_mutex); + if (likely(c1->d_parent != p2)) + return lock_two_directories(c1->d_parent, p2); + + inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); + mutex_unlock(&c1->d_sb->s_vfs_rename_mutex); + return NULL; +} +EXPORT_SYMBOL(lock_rename_child); + void unlock_rename(struct dentry *p1, struct dentry *p2) { inode_unlock(p1->d_inode); diff --git a/include/linux/namei.h b/include/linux/namei.h index 40c693525f79..7868732cce24 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -83,6 +83,7 @@ extern int follow_down(struct path *); extern int follow_up(struct path *); extern struct dentry *lock_rename(struct dentry *, struct dentry *); +extern struct dentry *lock_rename_child(struct dentry *, struct dentry *); extern void unlock_rename(struct dentry *, struct dentry *); extern int __must_check nd_jump_link(struct path *path);