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Re: [PATCH 6/3] xfs: make largest supported offset less shouty

To: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Subject: Re: [PATCH 6/3] xfs: make largest supported offset less shouty
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Mon, 30 Apr 2012 13:03:30 +1000
Cc: xfs@xxxxxxxxxxx
In-reply-to: <20120430011124.GD3283@dastard>
References: <1335519922-14371-1-git-send-email-david@xxxxxxxxxxxxx> <20120429125729.GU9541@dastard> <20120429215830.GQ19889@xxxxxxxxxxxxx> <20120430011124.GD3283@dastard>
User-agent: Mutt/1.5.21 (2010-09-15)
On Mon, Apr 30, 2012 at 11:11:24AM +1000, Dave Chinner wrote:
> On Sun, Apr 29, 2012 at 05:58:30PM -0400, Christoph Hellwig wrote:
> > On Sun, Apr 29, 2012 at 10:57:29PM +1000, Dave Chinner wrote:
> > > From: Dave Chinner <dchinner@xxxxxxxxxx>
> > > 
> > > XFS_MAXIOFFSET() is just a simple macro that resolves to
> > > mp->m_maxioffset. It doesn't need to exist, and it just makes the
> > > code unnecessarily loud and shouty.
> > > 
> > > Make it quiet and easy to read.
> > 
> > Do we actually need to keep around a value in our superblock?
> > s_maxbytes in the VFS superblock already does this, and it seems like
> > at least our checks in the read path are superflous.

Actually, I can't find where the read path checks against
s_maxbytes. It's not in generic_segment_check(), and there appears
to be no other range checks in the VFS. So I think that the check we
have in xfs_file_aio_read needs to remain....

> Ah, we do indeed keep the same value in s_maxbytes - that's one step
> removed from m_maxioffset because it uses the same function to
> calculate it, and they are done a long way apart. Ok, it looks like
> I've got a couple more patches to write to finish off this cleanup.

Still, we can now replace the copy-n-paste code in
xfs_file_aio_read() with a call to generic_segment_check() seeing as
it returns a sum of the iovec length now, and still kill


Dave Chinner

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