From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752524AbcJKFeZ (ORCPT ); Tue, 11 Oct 2016 01:34:25 -0400 Received: from out5-smtp.messagingengine.com ([66.111.4.29]:46054 "EHLO out5-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752452AbcJKFeW (ORCPT ); Tue, 11 Oct 2016 01:34:22 -0400 X-Sasl-enc: 6720oLecVdOl/DB+M+dEdLr5pqsNMgT/AYhxWL2c3KqF 1476164060 Subject: [PATCH 6/8] autofs - use path_is_mountpoint() to fix unreliable d_mountpoint() checks From: Ian Kent To: Andrew Morton Cc: autofs mailing list , Kernel Mailing List , "Eric W. Biederman" , linux-fsdevel , Omar Sandoval , Al Viro Date: Tue, 11 Oct 2016 13:34:18 +0800 Message-ID: <20161011053418.27645.15241.stgit@pluto.themaw.net> In-Reply-To: <20161011053352.27645.83962.stgit@pluto.themaw.net> References: <20161011053352.27645.83962.stgit@pluto.themaw.net> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ian Kent If an automount mount is clone(2)ed into a file system that is propagation private, when it later expires in the originating namespace, subsequent calls to autofs ->d_automount() for that dentry in the original namespace will return ELOOP until the mount is umounted in the cloned namespace. Now that a struct path is available where needed use path_is_mountpoint() instead of d_mountpoint() so we don't get false positives when checking if a dentry is a mount point in the current namespace. Signed-off-by: Ian Kent Cc: Al Viro Cc: Eric W. Biederman Cc: Omar Sandoval --- fs/autofs4/root.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index d47930ad..d7e48fe 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -107,12 +107,15 @@ static int autofs4_dir_open(struct inode *inode, struct file *file) { struct dentry *dentry = file->f_path.dentry; struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb); + struct path path; pr_debug("file=%p dentry=%p %pd\n", file, dentry, dentry); if (autofs4_oz_mode(sbi)) goto out; + path = file->f_path; + /* * An empty directory in an autofs file system is always a * mount point. The daemon must have failed to mount this @@ -123,7 +126,7 @@ static int autofs4_dir_open(struct inode *inode, struct file *file) * it. */ spin_lock(&sbi->lookup_lock); - if (!d_mountpoint(dentry) && simple_empty(dentry)) { + if (!path_is_mountpoint(&path) && simple_empty(dentry)) { spin_unlock(&sbi->lookup_lock); return -ENOENT; } @@ -372,15 +375,15 @@ static struct vfsmount *autofs4_d_automount(struct path *path) /* * If the dentry is a symlink it's equivalent to a directory - * having d_mountpoint() true, so there's no need to call back - * to the daemon. + * having path_is_mountpoint() true, so there's no need to call + * back to the daemon. */ if (d_really_is_positive(dentry) && d_is_symlink(dentry)) { spin_unlock(&sbi->fs_lock); goto done; } - if (!d_mountpoint(dentry)) { + if (!path_is_mountpoint(path)) { /* * It's possible that user space hasn't removed directories * after umounting a rootless multi-mount, although it @@ -434,8 +437,13 @@ static int autofs4_d_manage(struct path *path, bool rcu_walk) /* The daemon never waits. */ if (autofs4_oz_mode(sbi)) { - if (!d_mountpoint(dentry)) - return -EISDIR; + if (rcu_walk) { + if (!path_is_mountpoint_rcu(path)) + return -EISDIR; + } else { + if (!path_is_mountpoint(path)) + return -EISDIR; + } return 0; } @@ -463,7 +471,7 @@ static int autofs4_d_manage(struct path *path, bool rcu_walk) if (ino->flags & AUTOFS_INF_WANT_EXPIRE) return 0; - if (d_mountpoint(dentry)) + if (path_is_mountpoint_rcu(path)) return 0; inode = d_inode_rcu(dentry); if (inode && S_ISLNK(inode->i_mode)) @@ -490,7 +498,7 @@ static int autofs4_d_manage(struct path *path, bool rcu_walk) * we can avoid needless calls ->d_automount() and avoid * an incorrect ELOOP error return. */ - if ((!d_mountpoint(dentry) && !simple_empty(dentry)) || + if ((!path_is_mountpoint(path) && !simple_empty(dentry)) || (d_really_is_positive(dentry) && d_is_symlink(dentry))) status = -EISDIR; }