Subject: Re: [PATCH 2/3] NFS: Cleanup of the nfs_pageio code in preparation
 for a pnfs bugfix
From: Trond Myklebust <Trond.Myklebust@netapp.com>
To: Boaz Harrosh <bharrosh@panasas.com>
Cc: Benny Halevy <bhalevy@panasas.com>, linux-nfs@vger.kernel.org
Date: Thu, 09 Jun 2011 14:13:15 -0400
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On Thu, 2011-06-09 at 10:51 -0700, Boaz Harrosh wrote:

> 1. We will then need to go through the ld in .pg_init

No. I'll fix nfs_pageio_init_read() and friends by replacing
pnfs_get_read_ops() by something more appropriate.

> 2. What happens in the none pnfs-IO error case pg_bsize will need to be
>    saved and restored to MDS value.

Yes, but if you are falling back to read/write-through-mds, then you
need to re-run the coalescing _anyway_, since the total length of the
request needs to fit in an rsize/wsize sized request.

> 3. At least in objects there is no such constant limit, it all depends on
>    the layout, start and end. I thought the all point of .pg_test was
>    exactly for avoiding a constant pg_bsize. (This is what we had before)
> 4. All "the tests make no sense..." should be moved to the no-pnfs case
>    please point these you found out, we'll need to fix them.
> 
> Please understand that for none-files layouts pg_bsize is when IO goes
> through MDS only.

As I said, I don't see how fallback to MDS can work correctly today for
the objects case for arbitrary values of rsize/wsize.

Cheers
  Trond
-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@netapp.com
www.netapp.com