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Re: review: don't block non-blocking writes when frozen

To: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Subject: Re: review: don't block non-blocking writes when frozen
From: David Chinner <dgc@xxxxxxx>
Date: Tue, 24 Apr 2007 09:13:37 +1000
Cc: David Chinner <dgc@xxxxxxx>, gnb@xxxxxxx, xfs-oss <xfs@xxxxxxxxxxx>, nfs@xxxxxxxxxxxxxxxxxxxxx
In-reply-to: <20070423212715.GF13572@xxxxxxxxxxxxx>
References: <20070423002616.GY32602149@xxxxxxxxxxxxxxxxx> <20070423212715.GF13572@xxxxxxxxxxxxx>
Sender: xfs-bounce@xxxxxxxxxxx
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On Mon, Apr 23, 2007 at 10:27:15PM +0100, Christoph Hellwig wrote:
> On Mon, Apr 23, 2007 at 10:26:16AM +1000, David Chinner wrote:
> > 
> > Prevent nfsds for blocking trying to write to a frozen filesystem
> > or a filesystem in the process of freezing.
> 
> Looks good for trees actually having support for non-blocking file
> I/O, which doesn't include mainline.  (So please don't send this
> upstead)

Yeah - you NACKed that a year ago based on the fact it would never
get used by mainline code:

http://marc.info/?l=linux-nfs&m=114683005119982&w=2

So, given the catch-22 you've just presented us can we revisit the
nfsd non-blocking I/O issue again?  This affects anyone using DM
snapshots on their NFS servers and has nothing to do with HSMs
or DMAPI...

FWIW, you can still do non-blocking userspace I/O to a file, so this
XFS patch is still valid for mainline (that's how I tested it).

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group


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