From: Christoph Hellwig <hch@infradead.org>
To: Jan Blunck <jblunck@suse.de>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 1/4] Union mount documentation.
Date: Wed, 20 Jun 2007 14:25:42 +0100 [thread overview]
Message-ID: <20070620132542.GA6169@infradead.org> (raw)
In-Reply-To: <f5b7ec$f4g$1@sea.gmane.org>
On Wed, Jun 20, 2007 at 12:43:56PM +0000, Jan Blunck wrote:
> On Wed, 20 Jun 2007 13:32:23 +0100, Christoph Hellwig wrote:
>
> > On Wed, Jun 20, 2007 at 07:29:55AM +0000, Jan Blunck wrote:
> >> Mounting a file system twice is bad in the first place. This should be
> >> done by using bind mounts and bind a mounted file system into a union.
> >> After that the normal locking rules apply (and hopefully work ;).
> >
> > From the kernel POV mounting a filesystem twice is the same as doing
> > a bind mount.
>
> Somehow I thought about doing this:
>
> mount /dev/dasda1 /mnt/A
> mount /dev/dasda1 /mnt/B
>
> ... which doesn't result in a bind mount.
But the kernel internal effect is exactly the same. One superblock instance,
two vfsmounts referring to it.
next prev parent reply other threads:[~2007-06-20 13:25 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-20 5:50 [RFC PATCH 0/4] New approach to VFS based union mount Bharata B Rao
2007-06-20 5:51 ` [RFC PATCH 1/4] Union mount documentation Bharata B Rao
2007-06-20 5:59 ` Arjan van de Ven
2007-06-20 7:29 ` Jan Blunck
2007-06-20 12:32 ` Christoph Hellwig
2007-06-20 12:43 ` Jan Blunck
2007-06-20 13:25 ` Christoph Hellwig [this message]
2007-06-20 17:28 ` Erez Zadok
2007-06-21 5:25 ` Bharata B Rao
2007-06-21 16:29 ` Josef Sipek
2007-06-21 16:39 ` Erez Zadok
2007-06-20 12:56 ` Jan Blunck
2007-06-20 8:11 ` Jan Blunck
2007-06-20 9:09 ` Bharata B Rao
2007-06-20 5:52 ` [RFC PATCH 2/4] Mount changes to support union mount Bharata B Rao
2007-06-20 7:47 ` Jan Blunck
2007-06-20 8:53 ` Bharata B Rao
2007-06-21 16:40 ` Josef Sipek
2007-06-20 5:53 ` [RFC PATCH 3/4] Lookup " Bharata B Rao
2007-06-20 7:51 ` Jan Blunck
2007-06-20 8:56 ` Bharata B Rao
2007-06-20 5:54 ` [RFC PATCH 4/4] Directory listing support for union mounted directories Bharata B Rao
2007-06-20 12:09 ` Christoph Hellwig
2007-06-20 14:22 ` Trond Myklebust
2007-06-20 17:02 ` Christoph Hellwig
2007-06-20 17:44 ` Trond Myklebust
2007-06-30 9:43 ` Christoph Hellwig
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