From mboxrd@z Thu Jan 1 00:00:00 1970 From: "J. Bruce Fields" Subject: Re: [RFC PATCH 2/3] vfs: Add open by file handle support Date: Fri, 26 Feb 2010 14:21:25 -0500 Message-ID: <20100226192125.GB23556@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> <20100220201322.GA11152@cynthia.pants.nu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Brad Boyer , "Aneesh Kumar K.V" , hch@infradead.org, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org To: Andreas Dilger Return-path: Received: from fieldses.org ([174.143.236.118]:55317 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965829Ab0BZTUg (ORCPT ); Fri, 26 Feb 2010 14:20:36 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Sun, Feb 21, 2010 at 11:42:45AM -0700, Andreas Dilger wrote: > Yes, we looked at this in the past for Lustre as well, and while we had > proposed a patch for the NFSd code to extract the FSID from the > filesystem, it was turned down because "setting the FSID via a userspace > file is the right thing to do". I have enough on my plate not to wage an > uphill battle for this. > > I don't necessarily agree, because that means administering yet another > config parameter outside the filesystem on all of the servers. I don't > mind allowing userspace to override the fs UUID-based FSID, but why not > let this be used by default instead of the devno (which is increasingly > dynamic these days). > > Maybe with more clustered filesystems in the kernel these days this idea > can gain more traction. I agree that a cluster filesystem shouldn't need fsid= set right across all servers. But doesn't the libblkid uuid stuff as it's now implemented give you what you need? >> I haven't started writing any code to do this, but I have looked >> at the current NFS FH code and it seems like it should be reasonable >> to add a new set of methods to allow another FS specific field. > > First would be a method to extract the FSID/UUID from the filesystem. > That is immediately useful for even local configs. > >> The hardest part seems to be holding the size down to the old NFS v2 >> protocol limits. > > Would it not be possible to encode the FSID/UUID only into NFSv3/v4 > handles, and leave the NFSv2 handles without this information? I > imagine the usage of NFSv2 is growing ever smaller, and there isn't a > requirement to add this extra field there. Yeah, I don't think NFSv2 support should be a high priority for new features. --b.