From patchwork Wed Apr 27 02:32:44 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Namjae Jeon X-Patchwork-Id: 12828200 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 4D22DC4332F for ; Wed, 27 Apr 2022 02:33:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357200AbiD0CgY (ORCPT ); Tue, 26 Apr 2022 22:36:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52554 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1357196AbiD0CgX (ORCPT ); Tue, 26 Apr 2022 22:36:23 -0400 Received: from mail-pj1-f49.google.com (mail-pj1-f49.google.com [209.85.216.49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4DA6265D08; Tue, 26 Apr 2022 19:33:14 -0700 (PDT) Received: by mail-pj1-f49.google.com with SMTP id r9so261092pjo.5; Tue, 26 Apr 2022 19:33:14 -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=1W2RKO987hXL9y5yznf2QhQLVbTnMF3nzUrepuDGKL8=; b=mBkEZ2og8l6zbr8RQ3bkN/I1wSBj/WU7LF87tjkNsVZlpkvLk3vd45SzYg20Dqyl65 GgyyrLpfRXkt16rrifcVHZ7QqreuI1lOYquOrgiBtyqc/XxohTt8yLcpFJaDzHi7ZQvJ 2owNep+EjZhE0Pv2BWrgxSyHbjCrLV9zQ+ZbSwIlAmH+V8ZpRXoUZ9SZo0fTs4409DO8 eLw8Nrf82OL6O4KGBS2ZAemhnIRW+PQxpPhi/DTMSYYJ+372wj6VH9Ll0mUTyM4fXbvE HUZHVrZ6Pl9ODq51uNXdo1n5FzCSNwxwpLJyR5OaSEWwUgZWtOUjI7xlztMb+ZlzBcfw l/+A== X-Gm-Message-State: AOAM530fF3o+ylJNI+gTJ59of+t1mQQyckUGQXlXvPICo5ae2fhOvYdR fFbuLDRfVufAuR7WFaMkpiGO1QXS4EA= X-Google-Smtp-Source: ABdhPJzQiW5sn12iBxVD1Mqps+q31XGc4E22Ly9+CV/gqjhsk3y6umNH7QRHHh7WPRa2+TvdjXGo+A== X-Received: by 2002:a17:90a:d0c1:b0:1d2:c00a:8656 with SMTP id y1-20020a17090ad0c100b001d2c00a8656mr30417109pjw.235.1651026793399; Tue, 26 Apr 2022 19:33:13 -0700 (PDT) Received: from localhost.localdomain ([211.49.23.9]) by smtp.gmail.com with ESMTPSA id t1-20020a628101000000b0050d47199857sm7338564pfd.73.2022.04.26.19.33.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 26 Apr 2022 19:33:12 -0700 (PDT) From: Namjae Jeon To: linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org Cc: smfrench@gmail.com, hyc.lee@gmail.com, senozhatsky@chromium.org, Al Viro , Namjae Jeon Subject: [PATCH 2/3] fs: introduce lock_rename_child() helper Date: Wed, 27 Apr 2022 11:32:44 +0900 Message-Id: <20220427023245.7327-2-linkinjeon@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220427023245.7327-1-linkinjeon@kernel.org> References: <20220427023245.7327-1-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 3f1829b3ab5b..516b8d147744 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2954,20 +2954,10 @@ 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); @@ -2986,8 +2976,42 @@ 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 4858c3cdf7c6..e6949d4ba188 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -77,6 +77,7 @@ 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);