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From: Mike Waychison <Michael.Waychison@Sun.COM>
To: viro@parcelfarce.linux.theplanet.co.uk
Cc: autofs mailing list <autofs@linux.kernel.org>,
	"Ogden, Aaron A." <aogden@unocal.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Ian Kent <raven@themaw.net>
Subject: Re: [RFC] Towards a Modern Autofs
Date: Fri, 09 Jan 2004 14:41:30 -0500	[thread overview]
Message-ID: <3FFF03EA.4060603@sun.com> (raw)
In-Reply-To: <20040108183135.GE30321@parcelfarce.linux.theplanet.co.uk>


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viro@parcelfarce.linux.theplanet.co.uk wrote:

>On Thu, Jan 08, 2004 at 08:52:31PM +0800, Ian Kent wrote:
>  
>
>>On Wed, 7 Jan 2004, H. Peter Anvin wrote:
>>
>>    
>>
>>>These are the mount traps Al Viro has been architecting.
>>>
>>>      
>>>
>>Please tell me about these.
>>
>>I have`nt seen any discussion on the implementation.
>>
>>Just a few sentences ....
>>    
>>
>
>Special vfsmount mounted somewhere; has no superblock associated with it;
>attempt to step on it triggers event; normal result of that event is to
>get a normal mount on top of it, at which point usual chaining logics
>will make sure that we don't see the trap until it's uncovered by removal
>of covering filesystem.  Trap (and everything mounted on it, etc.) can
>be removed by normal lazy umount.
>
>Basically, it's a single-point analog of autofs done entirely in VFS.
>The job of automounter is to maintain the traps and react to events.
>
>  
>
Is there any clear advantage to doing this in the VFS other than saving 
a superblock and a dentry/inode pair or two?

I remember talking to you about this, and I seem to recall that these 
mount traps would probably communicate using a struct file, so a 
trap-user would somehow receive events about when the trap was set 
off.   Will this communication model continue to work within a cloned 
namespace?  What happens if the trap-client closes the file?

-- 
Mike Waychison
Sun Microsystems, Inc.
1 (650) 352-5299 voice
1 (416) 202-8336 voice
mailto: Michael.Waychison@Sun.COM
http://www.sun.com

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NOTICE:  The opinions expressed in this email are held by me, 
and may not represent the views of Sun Microsystems, Inc.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 


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_______________________________________________
autofs mailing list
autofs@linux.kernel.org
http://linux.kernel.org/mailman/listinfo/autofs

WARNING: multiple messages have this Message-ID (diff)
From: Mike Waychison <Michael.Waychison@Sun.COM>
To: viro@parcelfarce.linux.theplanet.co.uk
Cc: Ian Kent <raven@themaw.net>,
	autofs mailing list <autofs@linux.kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Ogden, Aaron A." <aogden@unocal.com>,
	Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [autofs] [RFC] Towards a Modern Autofs
Date: Fri, 09 Jan 2004 14:41:30 -0500	[thread overview]
Message-ID: <3FFF03EA.4060603@sun.com> (raw)
In-Reply-To: <20040108183135.GE30321@parcelfarce.linux.theplanet.co.uk>

[-- Attachment #1: Type: text/plain, Size: 1778 bytes --]

viro@parcelfarce.linux.theplanet.co.uk wrote:

>On Thu, Jan 08, 2004 at 08:52:31PM +0800, Ian Kent wrote:
>  
>
>>On Wed, 7 Jan 2004, H. Peter Anvin wrote:
>>
>>    
>>
>>>These are the mount traps Al Viro has been architecting.
>>>
>>>      
>>>
>>Please tell me about these.
>>
>>I have`nt seen any discussion on the implementation.
>>
>>Just a few sentences ....
>>    
>>
>
>Special vfsmount mounted somewhere; has no superblock associated with it;
>attempt to step on it triggers event; normal result of that event is to
>get a normal mount on top of it, at which point usual chaining logics
>will make sure that we don't see the trap until it's uncovered by removal
>of covering filesystem.  Trap (and everything mounted on it, etc.) can
>be removed by normal lazy umount.
>
>Basically, it's a single-point analog of autofs done entirely in VFS.
>The job of automounter is to maintain the traps and react to events.
>
>  
>
Is there any clear advantage to doing this in the VFS other than saving 
a superblock and a dentry/inode pair or two?

I remember talking to you about this, and I seem to recall that these 
mount traps would probably communicate using a struct file, so a 
trap-user would somehow receive events about when the trap was set 
off.   Will this communication model continue to work within a cloned 
namespace?  What happens if the trap-client closes the file?

-- 
Mike Waychison
Sun Microsystems, Inc.
1 (650) 352-5299 voice
1 (416) 202-8336 voice
mailto: Michael.Waychison@Sun.COM
http://www.sun.com

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NOTICE:  The opinions expressed in this email are held by me, 
and may not represent the views of Sun Microsystems, Inc.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 


[-- Attachment #2: Type: application/pgp-signature, Size: 251 bytes --]

  parent reply	other threads:[~2004-01-09 19:41 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-01-06 22:28 [RFC] Towards a Modern Autofs Ogden, Aaron A.
2004-01-06 22:28 ` [autofs] " Ogden, Aaron A.
2004-01-06 22:41 ` Mike Fedyk
2004-01-06 22:47 ` Tim Hockin
2004-01-06 22:53 ` Paul Raines
2004-01-06 22:53   ` [autofs] " Paul Raines
2004-01-07 14:05 ` Greg Wooledge
2004-01-07 23:14 ` Jim Carter
2004-01-07 23:14   ` [autofs] " Jim Carter
2004-01-07 23:32   ` H. Peter Anvin
2004-01-07 23:32     ` [autofs] " H. Peter Anvin
2004-01-08 12:52     ` Ian Kent
2004-01-08 12:52       ` Ian Kent
2004-01-08 18:31       ` viro
2004-01-09 18:43         ` Ian Kent
2004-01-09 18:43           ` [autofs] " Ian Kent
2004-01-09 19:41         ` Mike Waychison [this message]
2004-01-09 19:41           ` Mike Waychison
2004-01-09 19:57           ` H. Peter Anvin
2004-01-09 19:57             ` [autofs] " H. Peter Anvin
2004-01-09 21:31             ` Mike Waychison
2004-01-09 21:31               ` [autofs] " Mike Waychison
2004-01-09 21:36               ` H. Peter Anvin
2004-01-09 21:36                 ` [autofs] " H. Peter Anvin
  -- strict thread matches above, loose matches on Subject: below --
2004-01-12 22:50 Tim Hockin
2004-01-13  1:30 ` Ian Kent
2004-01-12 16:58 [autofs] " Mike Waychison
2004-01-13  1:54 ` Ian Kent
2004-01-13 19:01   ` Mike Waychison
2004-01-10  5:43 [autofs] " Ian Kent
2004-01-12 13:07 ` Mike Waychison
2004-01-12 16:01   ` raven
2004-01-13 18:46     ` Mike Waychison
2004-01-08 15:39 [autofs] " Mike Waychison
2004-01-09 18:20 ` Ian Kent
2004-01-09 20:06   ` Mike Waychison
2004-01-09 20:51   ` Jim Carter
2004-01-06 23:34 Ogden, Aaron A.
2004-01-06 23:26 Ogden, Aaron A.
2004-01-06 19:55 Mike Waychison
2004-01-06 19:55 ` Mike Waychison
2004-01-06 21:01 ` H. Peter Anvin
2004-01-06 21:44   ` Mike Waychison
2004-01-06 21:50   ` Tim Hockin
2004-01-06 22:06     ` H. Peter Anvin
     [not found]       ` <20040106221502.GA7398@hockin.org>
2004-01-06 22:20         ` H. Peter Anvin
2004-01-07 16:19           ` Mike Waychison
2004-01-07 21:14 ` Jim Carter
2004-01-07 22:55   ` Mike Waychison
2004-01-08 12:00     ` Ian Kent
2004-01-08 17:34       ` [autofs] " H. Peter Anvin
2004-01-08 23:42         ` Michael Clark
2004-01-09 20:28           ` Mike Waychison
2004-01-09 20:54             ` H. Peter Anvin
2004-01-09 21:43               ` Mike Waychison
2004-01-09 18:32         ` Ian Kent
2004-01-09 20:52           ` Mike Waychison
2004-01-08  0:48   ` Ian Kent

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