Subject: Re: [PATCH 15/15] pnfs: layout roc code
From: Trond Myklebust <Trond.Myklebust@netapp.com>
To: Fred Isaman <iisaman@netapp.com>
Cc: linux-nfs@vger.kernel.org
In-Reply-To: <1292990449-20057-16-git-send-email-iisaman@netapp.com>
References: <1292990449-20057-1-git-send-email-iisaman@netapp.com>
	 <1292990449-20057-16-git-send-email-iisaman@netapp.com>
Content-Type: text/plain; charset="UTF-8"
Date: Wed, 22 Dec 2010 17:00:10 -0500
Message-ID: <1293055210.6422.23.camel@heimdal.trondhjem.org>
Sender: linux-nfs-owner@vger.kernel.org
MIME-Version: 1.0

On Tue, 2010-12-21 at 23:00 -0500, Fred Isaman wrote:
> A lsyout can request return-on-close.  How this interacts with the
> forgetful model of never sending LAYOUTRETURNS is a bit ambiguous.
> We forget any layouts marked roc, and wait for them to be completely
> forgotten before continuing with the close.  In addition, to compensate
> for races with any inflight LAYOUTGETs, and the fact that we do not get
> any layout stateid back from the server, we set the barrier to the worst
> case scenario of current_seqid + number of outstanding LAYOUTGETS.
> 
> Signed-off-by: Fred Isaman <iisaman@netapp.com>
> ---
>  fs/nfs/inode.c         |    1 +
>  fs/nfs/nfs4_fs.h       |    2 +-
>  fs/nfs/nfs4proc.c      |   21 +++++++++++-
>  fs/nfs/nfs4state.c     |    7 +++-
>  fs/nfs/pnfs.c          |   83 ++++++++++++++++++++++++++++++++++++++++++++++++
>  fs/nfs/pnfs.h          |   28 ++++++++++++++++
>  include/linux/nfs_fs.h |    1 +
>  7 files changed, 138 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> index 43a69da..c64bb40 100644
> diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
> index 29d504d..90515de 100644
> --- a/include/linux/nfs_fs.h
> +++ b/include/linux/nfs_fs.h
> @@ -190,6 +190,7 @@ struct nfs_inode {
>  	struct rw_semaphore	rwsem;
>  
>  	/* pNFS layout information */
> +	struct rpc_wait_queue lo_rpcwaitq;
>  	struct pnfs_layout_hdr *layout;
>  #endif /* CONFIG_NFS_V4*/
>  #ifdef CONFIG_NFS_FSCACHE

I believe that I've asked this before. Why do we need a per-inode
rpc_wait_queue just to support pnfs? That's a significant expansion of
an already bloated structure.

Can we please either make this a single per-filesystem wait queue, or
else possibly a pool of wait queues?

Trond

-- 
Trond Myklebust
Linux NFS client maintainer

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