From patchwork Tue Sep 20 22:43:37 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Namjae Jeon X-Patchwork-Id: 12982754 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 B08EAC54EE9 for ; Tue, 20 Sep 2022 22:44:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229529AbiITWoF (ORCPT ); Tue, 20 Sep 2022 18:44:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55456 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230295AbiITWnz (ORCPT ); Tue, 20 Sep 2022 18:43:55 -0400 Received: from mail-pg1-f169.google.com (mail-pg1-f169.google.com [209.85.215.169]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 15E956CF4E; Tue, 20 Sep 2022 15:43:55 -0700 (PDT) Received: by mail-pg1-f169.google.com with SMTP id q9so4131075pgq.8; Tue, 20 Sep 2022 15:43:55 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date; bh=5K/RIYItWzBwJjJUuRJANuwpWyKGk0xDPz8dpbGp/5Q=; b=M2Cm8ttunzNdi4LfFHR3eMFw5NVLP0htZLeQV/+x2JQx8gncjZ6BBbpYpTEaKImbDm AECYIeYMBIfXzZ3o9KxaTEGmbxkokKT3e6TdZlcrO0QDazmZE6kh1yJP7YFFj6rx1aIC cH3g3eIqmBBrLFdsZp1L/klX45Vb0VROLgR3RV0CPPnRDg9YYRJLajyPO28ZRCL+Rnhu WGegEbTl/tOlR6xod0S9Za9le/bQAePpv+5V01FKzuuu2mNzlGHpq+st5MtKmZu4WcVc 3bfLxmxEJcpF/MJiwh3V7ZFi07z5qwAtI53AZEjspSB2kcsXiT4gmZbDjiV7bTtaoV/l Ek1g== X-Gm-Message-State: ACrzQf3ypsunHZpBBzsfIyqrUaW4FMxw3NRa4aSciHJIk1eLmsJYrPpV zN+MLiTYJxkMFc/3yOQy6xQ= X-Google-Smtp-Source: AMsMyM4s2NkTqs95w5UpRHvzngsMunBpMamjPGnmNoMdEifSb4FpCGIfGhVkMwdsd1JhQGDAE5HqGQ== X-Received: by 2002:a63:ff55:0:b0:438:fa5d:af36 with SMTP id s21-20020a63ff55000000b00438fa5daf36mr22100920pgk.533.1663713834592; Tue, 20 Sep 2022 15:43:54 -0700 (PDT) Received: from localhost.localdomain ([211.49.23.9]) by smtp.gmail.com with ESMTPSA id 13-20020a62140d000000b0053e93aa8fb9sm451352pfu.71.2022.09.20.15.43.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Sep 2022 15:43:54 -0700 (PDT) From: Namjae Jeon To: viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-cifs@vger.kernel.org Cc: smfrench@gmail.com, senozhatsky@chromium.org, tom@talpey.com, atteh.mailbox@gmail.com, Namjae Jeon Subject: [PATCH v7 2/3] fs: introduce lock_rename_child() helper Date: Wed, 21 Sep 2022 07:43:37 +0900 Message-Id: <20220920224338.22217-3-linkinjeon@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220920224338.22217-1-linkinjeon@kernel.org> References: <20220920224338.22217-1-linkinjeon@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-cifs@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 53b4bc094db2..5ff7f2a9e54e 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2979,20 +2979,10 @@ 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); @@ -3011,8 +3001,42 @@ 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);