linux-kernel - Re: [RFC 2/2] fanotify: emit FAN_MODIFY

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Message-ID: <20170320115255.viwh44ouh4fagnqu@rgvaio>
Date:   Mon, 20 Mar 2017 12:52:55 +0100
From:   Filip Štědronský <r.lkml@...narg.cz>
To:     Jan Kara <jack@...e.cz>
Cc:     Amir Goldstein <amir73il@...il.com>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Marko Rauhamaa <marko.rauhamaa@...ecure.com>
Subject: Re: [RFC 2/2] fanotify: emit FAN_MODIFY_DIR on filesystem changes

Hi,

On Sun, Mar 19, 2017 at 07:04:13PM +0100, Jan Kara wrote:
> How come? In current kernel the call looks like:
> 
> vfs_mknod(d_inode(path.dentry), dentry, mode, dev->devt);
> 
> so the path is available there... I've actually quickly checked all
> vfs_mknod() callers and they all seem to have path available.

terribly sorry, must have misremembered something. Been staring at the
code long into the night. You are quite right.

But it is an internal mount so userspace never gets the notifications.
The same goes for the cloned upper mount in overlayfs. This might be
considered ok, because the change is semantically "internal" and does
not originate through any userspace-visible mountpoint. Superblock
watches would solve this case.

Otherwise it seems feasible to pass a path to all VFS functions.

Filip