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Subject: Re: [PATCH 2/6] Adjust watch_queue documentation to mention mount and
 superblock watches. [ver #5]
To:     David Howells <dhowells@redhat.com>
Cc:     viro@zeniv.linux.org.uk, Casey Schaufler <casey@schaufler-ca.com>,
        Stephen Smalley <sds@tycho.nsa.gov>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        nicolas.dichtel@6wind.com, raven@themaw.net,
        Christian Brauner <christian@brauner.io>,
        keyrings@vger.kernel.org, linux-usb@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
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 <156173703546.15650.14319137940607993268.stgit@warthog.procyon.org.uk>
 <8212.1561971170@warthog.procyon.org.uk>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <90d07cf5-5ba4-1fb6-72b3-f120423a7726@infradead.org>
Date:   Mon, 1 Jul 2019 07:52:02 -0700
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On 7/1/19 1:52 AM, David Howells wrote:
> Randy Dunlap <rdunlap@infradead.org> wrote:
> 
>> I'm having a little trouble parsing that sentence.
>> Could you clarify it or maybe rewrite/modify it?
>> Thanks.
> 
> How about:
> 
>   * ``info_filter`` and ``info_mask`` act as a filter on the info field of the
>     notification record.  The notification is only written into the buffer if::
> 
> 	(watch.info & info_mask) == info_filter
> 
>     This could be used, for example, to ignore events that are not exactly on
>     the watched point in a mount tree by specifying NOTIFY_MOUNT_IN_SUBTREE
>     must not be set, e.g.::
> 
> 	{
> 		.type = WATCH_TYPE_MOUNT_NOTIFY,
> 		.info_filter = 0,
> 		.info_mask = NOTIFY_MOUNT_IN_SUBTREE,
> 		.subtype_filter = ...,
> 	}
> 
>     as an event would be only permissible with this filter if::
> 
>     	(watch.info & NOTIFY_MOUNT_IN_SUBTREE) == 0
> 
> David
> 

Yes, better.  Thanks.

-- 
~Randy