From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754546Ab3IHLdV (ORCPT ); Sun, 8 Sep 2013 07:33:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:27109 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752440Ab3IHLdT (ORCPT ); Sun, 8 Sep 2013 07:33:19 -0400 Date: Sun, 8 Sep 2013 07:33:20 -0400 From: Jeff Layton To: Ian Kent Cc: Linus Torvalds , linux-fsdevel , autofs mailing list , Al Viro , Kernel Mailing List Subject: Re: [PATCH 2/2] autofs4 - fix device ioctl mount lookup Message-ID: <20130908073320.6c15d449@tlielax.poochiereds.net> In-Reply-To: <20130908084722.14798.24320.stgit@perseus.fritz.box> References: <20130908084714.14798.32490.stgit@perseus.fritz.box> <20130908084722.14798.24320.stgit@perseus.fritz.box> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 08 Sep 2013 16:47:23 +0800 Ian Kent wrote: > When reconnecting to automounts at startup an autofs ioctl is used > to find the device and inode of existing mounts so they can be used > to open a file descriptor of possibly covered mounts. > > At this time the the caller might not yet "own" the mount so it can > trigger calling ->d_automount(). This causes automount to hang when > trying to reconnect to direct or offset mount types. > > Consequently kern_path() can't be used but path_mntpointat() can be. > > Signed-off-by: Ian Kent > Cc: Jeff Layton > Cc: Al Viro > --- > fs/autofs4/dev-ioctl.c | 23 ++++++++++++----------- > 1 file changed, 12 insertions(+), 11 deletions(-) > > diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c > index 9183821..228866f 100644 > --- a/fs/autofs4/dev-ioctl.c > +++ b/fs/autofs4/dev-ioctl.c > @@ -183,13 +183,14 @@ static int autofs_dev_ioctl_protosubver(struct file *fp, > return 0; > } > > +/* Find the topmost mount satisfying test() */ > static int find_autofs_mount(const char *pathname, > struct path *res, > int test(struct path *path, void *data), > void *data) > { > struct path path; > - int err = kern_path(pathname, 0, &path); > + int err = user_path_mntpointat(AT_FDCWD, pathname, 0, &path); This looks wrong. "pathname" is a kernel string, not a __user one. I think what you need to do here is to turn user_path_mntpointat into a wrapper around a kern_path_mntpointat equivalent and then call that here. > if (err) > return err; > err = -ENOENT; > @@ -197,10 +198,9 @@ static int find_autofs_mount(const char *pathname, > if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) { > if (test(&path, data)) { > path_get(&path); > - if (!err) /* already found some */ > - path_put(res); > *res = path; > err = 0; > + break; > } > } > if (!follow_up(&path)) > @@ -498,12 +498,11 @@ static int autofs_dev_ioctl_askumount(struct file *fp, > * mount if there is one or 0 if it isn't a mountpoint. > * > * If we aren't supplied with a file descriptor then we > - * lookup the nameidata of the path and check if it is the > - * root of a mount. If a type is given we are looking for > - * a particular autofs mount and if we don't find a match > - * we return fail. If the located nameidata path is the > - * root of a mount we return 1 along with the super magic > - * of the mount or 0 otherwise. > + * lookup the path and check if it is the root of a mount. > + * If a type is given we are looking for a particular autofs > + * mount and if we don't find a match we return fail. If the > + * located path is the root of a mount we return 1 along with > + * the super magic of the mount or 0 otherwise. > * > * In both cases the the device number (as returned by > * new_encode_dev()) is also returned. > @@ -531,9 +530,11 @@ static int autofs_dev_ioctl_ismountpoint(struct file *fp, > > if (!fp || param->ioctlfd == -1) { > if (autofs_type_any(type)) > - err = kern_path(name, LOOKUP_FOLLOW, &path); > + err = user_path_mntpointat(AT_FDCWD, > + name, LOOKUP_FOLLOW, &path); > else > - err = find_autofs_mount(name, &path, test_by_type, &type); > + err = find_autofs_mount(name, &path, > + test_by_type, &type); ...ditto in these spots of course... > if (err) > goto out; > devid = new_encode_dev(path.dentry->d_sb->s_dev); > -- Jeff Layton