[pnfs] [PATCH 08/11] pnfs: enable short read handling for all drivers

[Benny Halevy]

On Apr. 10, 2008, 17:05 +0300, Fred Isaman <iisaman at citi.umich.edu> wrote:
> The nfs short read infrastructure is useful even for layout drivers
> that set PNFS_NO_RPC, so enable it.  In particular, it is necessary
> for the correct functioning of nfs_readpage_result_partial for the
> (NO_RPC) layout drivers to either enable short read handling, or
> ensure they return an error in task->tk_status upon a short read.
> 
> Signed-off-by: Fred Isaman <iisaman at citi.umich.edu>
> ---
>  fs/nfs/read.c |   11 +++++++----
>  1 files changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/nfs/read.c b/fs/nfs/read.c
> index 4055126..774a21a 100644
> --- a/fs/nfs/read.c
> +++ b/fs/nfs/read.c
> @@ -375,10 +375,6 @@ static int nfs_readpage_retry(struct rpc_task *task, struct nfs_read_data *data)
>  	struct nfs_readargs *argp = &data->args;
>  	struct nfs_readres *resp = &data->res;
>  
> -#ifdef CONFIG_PNFS
> -	if (data->pnfsflags & PNFS_NO_RPC)
> -		return 0;
> -#endif /* CONFIG_PNFS */
>  	if (resp->eof || resp->count == argp->count)
>  		return 0;
>  
> @@ -392,6 +388,13 @@ static int nfs_readpage_retry(struct rpc_task *task, struct nfs_read_data *data)
>  	argp->offset += resp->count;
>  	argp->pgbase += resp->count;
>  	argp->count -= resp->count;
> +#ifdef CONFIG_PNFS
> +	if (data->pnfsflags & PNFS_NO_RPC) {
> +		/* Note can't use return value, shouldn't really have one */

Hmm, I don't really like that.
What happens if we fail to get the layout?

> +		pnfs_try_to_read_data(data, data->call_ops);
> +		return -EAGAIN;
> +	}
> +#endif /* CONFIG_PNFS */
>  	rpc_restart_call(task);

Remind me why not go through rpc_restart_call for the residue?
(i.e. also for the PNFS_NO_RPC path)

>  	return -EAGAIN;
>  }