Date: Tue, 6 Jul 2010 12:10:02 -0400
From: "J. Bruce Fields" <bfields@fieldses.org>
To: "Aneesh Kumar K. V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Neil Brown <neilb@suse.de>, hch@infradead.org, viro@zeniv.linux.org.uk,
       adilger@sun.com, corbet@lwn.net, serue@us.ibm.com,
       hooanon05@yahoo.co.jp, linux-fsdevel@vger.kernel.org,
       sfrench@us.ibm.com, philippe.deniel@CEA.FR,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH -V14 0/11] Generic name to handle and open by handle
 syscalls
Message-ID: <20100706161002.GD7387@fieldses.org>
References: <1276621981-2774-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
 <871vbn2mk9.fsf@linux.vnet.ibm.com>
 <20100702064108.64034561@notabene.brown>
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On Fri, Jul 02, 2010 at 02:45:45AM +0530, Aneesh Kumar K. V wrote:
> One use case i had was that if the userspace file server can directly
> work with the returned file system UUID,

I agree that the uuid should be split out from the rest of the
filehandle, but ...

> the it can build the file
> handle for client in a single call.

... I don't understand why both need to come in the same system call.
Is it purely an efficiency question?  If so, why do you expect this to
be significant?

(I would have thought that the system call overhead is so small, and so
many calls will already be required to perform the typical rpc, that
this would be insignificant.)

A filesystem uuid seems like a generally useful thing (maybe more so
than a filehandle), so it'd seem worth figuring out how to export that
separately.

--b.
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