[pnfs] [PATCH 19/20] 2.6-latest pnfs client no rpc nfs page cache cleanup

[Benny Halevy]

On Nov. 28, 2007, 23:33 +0200, andros at umich.edu wrote:
> From: Andy Adamson <andros at umich.edu>
> 
> Cleanup the nfs page cache after a non rpc pNFS I/O
> 
> The 2.6.18.3 client called pnfs_readpage_result_norpc() from pnfs_read_done
> to clean up after a pNFS I/O that used the page cache, but not NFS RPC.
> pnfs_readpage_result_norpc() contained code copied from
> the rpc_call_done routines nfs_readpage_result_full, and
> nfs_readpage_result_partial. It ran all the code that did not have to do
> with an rpc call, namely the NFS_PROTO(inode)->read_done and rpc_restart_call
> called in nfs_readpage_result. The PNFS_USE_FULL_CB was used to switch
> between the nfs_readpage_result_full and nfs_readpage_result_partial
> pieces of pnfs_readpage_result_norpc.
> 
> This patch provides a cleaner way of providing the same functionlality.
> The pNFS layout driver that uses the nfs page cache, but does not use
> RPC sets the new flag PNFS_NO_RPC in nfs_read_data->pnfsflags.
> This flag is checked in pnfs4_read_done, and in nfs_readpage_retry(), the
> two rpc specific portions of nfs_readpage_result_full and
> nfs_readpage_result_partial.

Since the control over the files layout driver is tighter, how about reversing
the logic and set a PNFS_IO_RPC flag for the files layout and MDS I/O
(and possibly future layout drivers that will use rpc to do DS I/O).

Also, how would pnfs4_read_done be called if the layout driver didn't
perform an rpc to do the I/O?

Benny

> 
> This allows the non rpc pNFS I/O path to use the same cleanup routines
> that NFS uses.
> 
> The PNFS_USE_FULL_CB is no longer needed.
> 
> Signed-off by: Andy Adamson<andros at umich.edu>
> ---
>  fs/nfs/nfs4proc.c       |    4 ++++
>  fs/nfs/pnfs.c           |   13 ++++++++++---
>  fs/nfs/read.c           |    4 ++++
>  include/linux/nfs_xdr.h |    2 +-
>  4 files changed, 19 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index aa40ab2..27b3be5 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -2944,6 +2944,10 @@ static int pnfs4_read_done(struct rpc_task *task, struct nfs_read_data *data)
>  	int status;
>  
>  	dprintk("--> %s\n", __func__);
> +
> +	if (data->pnfsflags & PNFS_NO_RPC)
> +		return 0;
> +
>  	status = task->tk_status >= 0 ? 0 : task->tk_status;
>  
>  	/* Is this a DS session */
> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
> index b072ec0..a7d47bc 100644
> --- a/fs/nfs/pnfs.c
> +++ b/fs/nfs/pnfs.c
> @@ -916,6 +916,8 @@ out:
>  
>  /* Post-read completion function.  Invoked by non RPC layout drivers
>   * to clean up read pages.
> + *
> + * NOTE: called must set data->pnfsflags PNFS_NO_RPC
>   */
>  static void
>  pnfs_read_done(struct nfs_read_data* data, ssize_t status, int eof)
> @@ -927,12 +929,17 @@ pnfs_read_done(struct nfs_read_data* data, ssize_t status, int eof)
>  	    pnfs_use_nfsv4_rproto(data->inode, data->args.count))
>  		return;
>  
> -	/* Status is the number of bytes written or an error code */
> +	/* Status is the number of bytes written or an error code
> +	 * the rpc_task is uninitialized, and tk_status is all that
> +	 * is used in the call done routines.
> +	*/
>  	data->task.tk_status = status;
>  	data->res.eof = eof;
>  	data->res.count = status;
> -	pnfs_readpage_result_norpc(&data->task, data);
> -	nfs_readdata_release(data);
> +
> +	/* call the NFS cleanup routines. */
> +	data->call_ops->rpc_call_done(&data->task, data);
> +	data->call_ops->rpc_release(data);
>  }
>  
>  /*
> diff --git a/fs/nfs/read.c b/fs/nfs/read.c
> index 4cf47c5..1852434 100644
> --- a/fs/nfs/read.c
> +++ b/fs/nfs/read.c
> @@ -381,6 +381,10 @@ 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;
>  
> diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
> index a6f429b..f747637 100644
> --- a/include/linux/nfs_xdr.h
> +++ b/include/linux/nfs_xdr.h
> @@ -1069,7 +1069,7 @@ struct nfs_read_data {
>  #ifdef CONFIG_PNFS
>  /* pnfsflag values */
>  #define PNFS_ISSYNC		0x0001   /* sync I/O request */
> -#define PNFS_USE_FULL_CB	0x0002   /* non rpc result callback switch */
> +#define PNFS_NO_RPC		0x0002   /* non rpc result callback switch */
>  #endif /* CONFIG_PNFS */
>  
>  struct nfs_write_data {