From: "Adamson, Andy" <William.Adamson@netapp.com>
To: "Myklebust, Trond" <Trond.Myklebust@netapp.com>
CC: "<linux-nfs@vger.kernel.org>" <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH 0/1] NFSv4.1 resend LAYOUTGET on data server invalid
 layout errors
Date: Wed, 4 Apr 2012 20:28:12 +0000
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References: <1333570957-2008-1-git-send-email-andros@netapp.com>
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This patch applies on top of the [PATCH Version 3 00/11] NFSv4.1 file layout data server quick failover patchset.

-->Andy

On Apr 4, 2012, at 4:22 PM, <andros@netapp.com>
 wrote:

> From: Andy Adamson <andros@netapp.com>
> 
>> From patch comments:
> 
> The "invalid layout" class of errors is handled by destroying the layout and
> getting a new layout from the server.  Currently, the layout must be
> destroyed before a new layout can be obtained.
> 
> This means that all references (e.g.lsegs) to the "to be destroyed" layout
> header must be dropped before it can be destroyed. This in turn means waiting
> for all in flight RPC's using the old layout as well as draining the data
> server session slot table wait queue.
> 
> Set the NFS_LAYOUT_INVALID flag to redirect I/O to the MDS while waiting for
> the old layout to be destroyed.
> 
> Testing:
> 
> Tested against a modified pynfs filelayout server with one DS. I mount the DS,
> set an NFS4ERR_BADHANDLE error in config/ops/write file which triggers the
> error on the "first" write. Umount the DS. Mount the MDS and run
> "dd if=/dev/zero of=/mnt/dd.out bs=4096 count=200". This results in a maxreqs
> worth of writes to the DS (8 for pynfs) before the NFS4ERR_BADHANDLE gets
> sent whereon writes are redirected to the MDS. Once the DS on the wire RPC's
> have all returned, and all the DS slot_tbl_waitq tasks are redirected to the
> MDS, the layout is destroyed, a new layout is obtained, and the writes return
> to pNFS before the 'dd' command finishes.
> 
> Andy Adamson (1):
>  NFSv4.1 resend LAYOUTGET on data server invalid layout errors
> 
> fs/nfs/nfs4filelayout.c |   27 +++++++++++++++++++++++----
> fs/nfs/nfs4filelayout.h |   13 +++++++++++++
> fs/nfs/pnfs.c           |    1 +
> fs/nfs/pnfs.h           |    1 +
> 4 files changed, 38 insertions(+), 4 deletions(-)
> 
> -- 
> 1.7.6.4
>