Message-ID: <4679ACBD.4090200@zytor.com>
Date: Wed, 20 Jun 2007 15:39:57 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Karel Zak <kzak@redhat.com>
CC: Al Viro <viro@ftp.linux.org.uk>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       linux-fsdevel@vger.kernel.org, util-linux-ng@vger.kernel.org
Subject: Re: Adding subroot information to /proc/mounts, or obtaining that
 through other means
References: <467994BD.6000403@zytor.com> <20070620210343.GQ21478@ftp.linux.org.uk> <20070620222437.GY7226@petra.dvoda.cz>
In-Reply-To: <20070620222437.GY7226@petra.dvoda.cz>
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Karel Zak wrote:
> 
>  Yeah. How about include propagation trees to this file?
> 
>  mountpoint + ID + relative path + type + options + propagation-flag +
>  {peer,master}-mount-id
> 
>  / 0xa917800 / ext3 rw PRIVATE
>  /mnt 0xa917100 / ext3 rw SHARED peer:0xa917100
>  /tmp 0xa917f00 /1 ext3 rw SLAVE master:0xa917100
> 

I think we're talking about a different meaning of "id" here... you seem
to be talking about the vfsmount pointer, whereas it was originally
proposed as mnt_sb->sb_dev.  Both are useful, for different reasons of
course.

We should include mnt_devname as well.

People are a bit nervous about exposing kernel pointers in userspace, I
have noticed; would it be better to add a "mnt_id" field to struct
vfsmount; this can simply be a counter assigned when the structure is
assigned and then never changed (it might have to be a 64-bit counter,
but I don't think that adding 8 bytes to struct vfsmount should be a
huge deal.)

Does that service everyone's needs?

	-hpa
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