From mboxrd@z Thu Jan  1 00:00:00 1970
From: Josef Bacik <jbacik@fusionio.com>
Subject: Re: [PATCH][RESEND] vfs: allow /proc/PID/maps to get device from stat
Date: Thu, 8 Aug 2013 09:02:07 -0400
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 <20130808121349.GC5180@infradead.org>
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Cc: Josef Bacik <jbacik@fusionio.com>, Mark Fasheh <mfasheh@suse.de>,
	<viro@ZenIV.linux.org.uk>, <linux-fsdevel@vger.kernel.org>,
	<linux-btrfs@vger.kernel.org>,
	Chris Mason <chris.mason@fusionio.com>,
	Andrew Vagin <avagin@gmail.com>
To: Christoph Hellwig <hch@infradead.org>
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On Thu, Aug 08, 2013 at 05:13:49AM -0700, Christoph Hellwig wrote:
> On Wed, Aug 07, 2013 at 04:51:46PM -0400, Josef Bacik wrote:
> > Not possible, this will break other things as subvolumes have their own inode
> > space, it will confuse applications that get multiples of an inode number for
> > different devices with the same st_dev.  Each subvolume has it's own anonymous
> > dev to segregate things.  Thanks,
> 
> Yes, it's the same old issue of btrfs volumes misbehaving, and the
> solution is still the same as 5 years ago: make sure each subvolume
> has it's own sb, vfsmount and gets automounted, similar to what nfs4
> does for this case.

This won't work, try having 10000 subvolumes with dirty inodes and do sync then
go skiing, you'll have time :).  Thanks,

Josef