From mboxrd@z Thu Jan  1 00:00:00 1970
From: "J. Bruce Fields" <bfields@fieldses.org>
Subject: Re: [RFC PATCH 2/3] vfs: Add open by file handle support
Date: Mon, 1 Mar 2010 16:25:59 -0500
Message-ID: <20100301212559.GI23539@fieldses.org>
References: <1266558149-11460-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1266558149-11460-3-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <AD5A6061-9B7B-4B29-A458-822E781C2588@sun.com> <20100220201322.GA11152@cynthia.pants.nu> <FB88A140-C2EB-4E62-9769-D2524C874C8C@sun.com> <20100226192125.GB23556@fieldses.org> <3FC42B3F-62C4-4E00-A641-0EC943833A0F@sun.com> <20100228190022.GA26297@fieldses.org> <5B44BB43-9C50-40CE-AEE2-F2E8662FB5FD@linuxhacker.ru>
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Cc: Andreas Dilger <adilger@Sun.COM>, Brad Boyer <flar@allandria.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	hch@infradead.org, viro@zeniv.linux.org.uk,
	linux-fsdevel@vger.kernel.org
To: Oleg Drokin <green@linuxhacker.ru>
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On Mon, Mar 01, 2010 at 01:25:56PM -0500, Oleg Drokin wrote:
> Hello!
> 
> On Feb 28, 2010, at 2:00 PM, J. Bruce Fields wrote:
> 
> >> If there is interest to revive this idea, I'll try to dig up the old  
> >> patches we had. I believe that they set a FS_NFS_FSID (or similarly  
> >> named) flag in the file_system_type, and possibly a method that  
> >> extracted this information for NFSd.
> > OK, sure, but if it's only of use to lustre than I don't see how to
> > justify a kernel patch.
> 
> I wonder how does GFS/OCFS2 do this? They cannot depend on the
> SAN block device to have same major:minor on every exporting node, right?

Right, libblkid calculates a uuid from the contents somehow.

> > Another option would be to provide an alternative to
> > nfs-utils/utils/mountd/cache.c's get_uuid() that can request the
> > filesystem's uuid (assuming you've got an easy way to get it from
> > userspace).  That might also save having to add yet another case to e.g.
> > fs/nfsd/nfsfh.c:set_version_and_fsid_type().
> 
> Hopefully there would be a standard way to request the uuid, not
> just a huge switch with separate code for every fstype.

Sure.

--b.