From: Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 2/2] add f_flags to struct statfs(64)
Date: Sat, 26 Jun 2010 15:12:08 +0200
Message-ID: <20100626131208.GB1838@lst.de>
References: <20100626093507.GB26371@lst.de> <20100626225547.52e76eb2@notabene.brown>
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Cc: Christoph Hellwig <hch@lst.de>, viro@zeniv.linux.org.uk,
	drepper@redhat.com, linux-fsdevel@vger.kernel.org
To: Neil Brown <neilb@suse.de>
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Sender: linux-fsdevel-owner@vger.kernel.org

On Sat, Jun 26, 2010 at 10:55:47PM +1000, Neil Brown wrote:
>  while we are adding flags to statfs, I wonder if it might be possible to do
>  something to make f_fsid more useful - particularly for nfs-utils.

f_fsid really isn't suitable for that.  Even filesystems that had UUIDs
since the dawn of days don't always store it there, e.g. XFS.  I wish
people had left it with that, but the recent rush to stupidly overload
it with an uuid light and using it in nfs-tools didn't help.

Having an API to expose a UUID to userspace would be useful, but f_fsid
isn't it.  If we'll have to add real statvfs syscalls we can add an
f_uuid field, but I'd rather not use up the reamining space in the
statfs structure for that.