Re: [PATCH 08/13] RFC: pnfs: filelayout: introduce minimal file layout driver

Trond Myklebust
2010-09-10T19:32:37Z

On Thu, 2010-09-02 at 14:00 -0400, Fred Isaman wrote:
> From: The pNFS Team <linux-nfs@vger.kernel.org>
>
> This driver just registers itself and supplies trivial mount/umount functions.
>
> Signed-off-by: TBD - melding/reorganization of several patches
> ---
> fs/nfs/Kconfig | 5 +++
> fs/nfs/Makefile | 3 ++
> fs/nfs/nfs4filelayout.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/nfs_fs.h | 1 +
> 4 files changed, 98 insertions(+), 0 deletions(-)
> create mode 100644 fs/nfs/nfs4filelayout.c
>
> diff --git a/fs/nfs/Kconfig b/fs/nfs/Kconfig
> index 5f1b936..980f2dc 100644
> --- a/fs/nfs/Kconfig
> +++ b/fs/nfs/Kconfig
> @@ -82,6 +82,11 @@ config NFS_V4_1
>
> If unsure, say N.
>
> +config PNFS_FILE_LAYOUT
> + tristate
> + depends on NFS_FS && NFS_V4_1
> + default m

Should be 'default y', otherwise it has an implicit dependency on
CONFIG_MODULES.

> +
> config ROOT_NFS
> bool "Root file system on NFS"
> depends on NFS_FS=y && IP_PNP
> diff --git a/fs/nfs/Makefile b/fs/nfs/Makefile
> index bb9e773..08a8889 100644
> --- a/fs/nfs/Makefile
> +++ b/fs/nfs/Makefile
> @@ -18,3 +18,6 @@ nfs-$(CONFIG_NFS_V4) += nfs4proc.o nfs4xdr.o nfs4state.o nfs4renewd.o \
> nfs-$(CONFIG_NFS_V4_1) += pnfs.o
> nfs-$(CONFIG_SYSCTL) += sysctl.o
> nfs-$(CONFIG_NFS_FSCACHE) += fscache.o fscache-index.o
> +
> +obj-$(CONFIG_PNFS_FILE_LAYOUT) += nfs_layout_nfsv41_files.o
> +nfs_layout_nfsv41_files-y := nfs4filelayout.o
> diff --git a/fs/nfs/nfs4filelayout.c b/fs/nfs/nfs4filelayout.c
> new file mode 100644
> index 0000000..c685196
> --- /dev/null
> +++ b/fs/nfs/nfs4filelayout.c
> @@ -0,0 +1,89 @@
> +/*
> + * Module for the pnfs nfs4 file layout driver.
> + * Defines all I/O and Policy interface operations, plus code
> + * to register itself with the pNFS client.
> + *
> + * Copyright (c) 2002
> + * The Regents of the University of Michigan
> + * All Rights Reserved
> + *
> + * Dean Hildebrand <dhildebz@umich.edu>
> + *
> + * Permission is granted to use, copy, create derivative works, and
> + * redistribute this software and such derivative works for any purpose,
> + * so long as the name of the University of Michigan is not used in
> + * any advertising or publicity pertaining to the use or distribution
> + * of this software without specific, written prior authorization. If
> + * the above copyright notice or any other identification of the
> + * University of Michigan is included in any copy of any portion of
> + * this software, then the disclaimer below must also be included.
> + *
> + * This software is provided as is, without representation or warranty
> + * of any kind either express or implied, including without limitation
> + * the implied warranties of merchantability, fitness for a particular
> + * purpose, or noninfringement. The Regents of the University of
> + * Michigan shall not be liable for any damages, including special,
> + * indirect, incidental, or consequential damages, with respect to any
> + * claim arising out of or in connection with the use of the software,
> + * even if it has been or is hereafter advised of the possibility of
> + * such damages.
> + */
> +
> +#include <linux/nfs_fs.h>
> +#include "pnfs.h"
> +
> +#define NFSDBG_FACILITY NFSDBG_PNFS_LD
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Dean Hildebrand <dhildebz@umich.edu>");
> +MODULE_DESCRIPTION("The NFSv4 file layout driver");
> +
> +int
> +filelayout_initialize_mountpoint(struct nfs_client *clp)
> +{
> + return 0;
> +}
> +
> +int
> +filelayout_uninitialize_mountpoint(struct nfs_client *clp)
> +{
> + dprintk("--> %s\n", __func__);
> +
> + return 0;
> +}
> +
> +struct layoutdriver_io_operations filelayout_io_operations = {

Should definitely be declared as 'const' (and possibly 'static').

> + .initialize_mountpoint = filelayout_initialize_mountpoint,
> + .uninitialize_mountpoint = filelayout_uninitialize_mountpoint,
> +};
> +
> +
> +struct pnfs_layoutdriver_type filelayout_type = {

Ditto.

> + .id = LAYOUT_NFSV4_1_FILES,
> + .name = "LAYOUT_NFSV4_1_FILES",
> + .ld_io_ops = &filelayout_io_operations,

Why do we need a separate 'struct layoutdriver_io_operations'? Any
reason those can't just be embedded in struct pnfs_layoutdriver_type?

> +};
> +
> +static int __init nfs4filelayout_init(void)
> +{
> + printk(KERN_INFO "%s: NFSv4 File Layout Driver Registering...\n",
> + __func__);
> +
> + /*
> + * Need to register file_operations struct with global list to indicate
> + * that NFS4 file layout is a possible pNFS I/O module
> + */
> + return pnfs_register_layoutdriver(&filelayout_type);
> +}
> +
> +static void __exit nfs4filelayout_exit(void)
> +{
> + printk(KERN_INFO "%s: NFSv4 File Layout Driver Unregistering...\n",
> + __func__);
> +
> + /* Unregister NFS4 file layout driver with pNFS client*/
> + pnfs_unregister_layoutdriver(&filelayout_type);
> +}
> +
> +module_init(nfs4filelayout_init);
> +module_exit(nfs4filelayout_exit);
> diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
> index 042c2bd..a0f49a3 100644
> --- a/include/linux/nfs_fs.h
> +++ b/include/linux/nfs_fs.h
> @@ -614,6 +614,7 @@ extern void * nfs_root_data(void);
> #define NFSDBG_MOUNT 0x0400
> #define NFSDBG_FSCACHE 0x0800
> #define NFSDBG_PNFS 0x1000
> +#define NFSDBG_PNFS_LD 0x2000
> #define NFSDBG_ALL 0xFFFF
>
> #ifdef __KERNEL__