From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2AC1E1C68C; Wed, 3 Jan 2024 16:58:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ZZIM1nT4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6626EC433C7; Wed, 3 Jan 2024 16:58:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1704301135; bh=8EyWs+XKrdNQ2XKxOz0Z1Q61VxLPofmQFAVqCGpk9+c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZZIM1nT4iX9aFHcpGX4kTVjs+a5w+lQFPnFYLIRvb/yeLBEQkYu5Qyzqwck33uE4p NSQLsS3mZtgDJ4EUAw8LxwmFf9aI9OKuoVG9NM5yqq/BcyT23ZHwVoeu/OEOY2DcIg /jDF989lnT387BqdfD9ptVkgZvXKRXRC8JACbQRI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Al Viro , Namjae Jeon , Sasha Levin Subject: [PATCH 6.1 017/100] fs: introduce lock_rename_child() helper Date: Wed, 3 Jan 2024 17:54:06 +0100 Message-ID: <20240103164858.675805667@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240103164856.169912722@linuxfoundation.org> References: <20240103164856.169912722@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Al Viro [ Upstream commit 9bc37e04823b5280dd0f22b6680fc23fe81ca325 ] 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 Signed-off-by: Al Viro Signed-off-by: Sasha Levin --- fs/namei.c | 68 ++++++++++++++++++++++++++++++++++++------- include/linux/namei.h | 1 + 2 files changed, 58 insertions(+), 11 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 5e1c2ab2ae709..6daaf84567195 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2980,20 +2980,10 @@ 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); @@ -3012,8 +3002,64 @@ struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) I_MUTEX_PARENT, 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); +/* + * c1 and p2 should be on the same fs. + */ +struct dentry *lock_rename_child(struct dentry *c1, struct dentry *p2) +{ + if (READ_ONCE(c1->d_parent) == p2) { + /* + * hopefully won't need to touch ->s_vfs_rename_mutex at all. + */ + inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); + /* + * now that p2 is locked, nobody can move in or out of it, + * so the test below is safe. + */ + if (likely(c1->d_parent == p2)) + return NULL; + + /* + * c1 got moved out of p2 while we'd been taking locks; + * unlock and fall back to slow case. + */ + inode_unlock(p2->d_inode); + } + + mutex_lock(&c1->d_sb->s_vfs_rename_mutex); + /* + * nobody can move out of any directories on this fs. + */ + if (likely(c1->d_parent != p2)) + return lock_two_directories(c1->d_parent, p2); + + /* + * c1 got moved into p2 while we were taking locks; + * we need p2 locked and ->s_vfs_rename_mutex unlocked, + * for consistency with lock_rename(). + */ + 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 00fee52df8423..2b66021c740dd 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -81,6 +81,7 @@ 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(const struct path *path); -- 2.43.0