NFSv4.1: pnfs: filelayout: add driver's LAYOUTGET and GETDEVICEINFO infrastructure (16b374ca) · Commits · 戴 / test

fs/nfs/Makefile

+1 −1

Original line number	Diff line number	Diff line
		@@ -20,4 +20,4 @@ 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
		nfs_layout_nfsv41_files-y := nfs4filelayout.o nfs4filelayoutdev.o

fs/nfs/client.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -255,6 +255,7 @@ void nfs_put_client(struct nfs_client *clp)
		nfs_free_client(clp);
		}
		}
		EXPORT_SYMBOL_GPL(nfs_put_client);

		#if defined(CONFIG_IPV6) \|\| defined(CONFIG_IPV6_MODULE)
		/*

fs/nfs/nfs4filelayout.c

+203 −1

Original line number	Diff line number	Diff line
		@@ -30,7 +30,9 @@
		*/

		#include <linux/nfs_fs.h>
		#include "pnfs.h"

		#include "internal.h"
		#include "nfs4filelayout.h"

		#define NFSDBG_FACILITY NFSDBG_PNFS_LD

		@@ -41,23 +43,223 @@ MODULE_DESCRIPTION("The NFSv4 file layout driver");
		int
		filelayout_initialize_mountpoint(struct nfs_server *nfss)
		{
		int status = pnfs_alloc_init_deviceid_cache(nfss->nfs_client,
		nfs4_fl_free_deviceid_callback);
		if (status) {
		printk(KERN_WARNING "%s: deviceid cache could not be "
		"initialized\n", __func__);
		return status;
		}
		dprintk("%s: deviceid cache has been initialized successfully\n",
		__func__);
		return 0;
		}

		/* Uninitialize a mountpoint by destroying its device list */
		int
		filelayout_uninitialize_mountpoint(struct nfs_server *nfss)
		{
		dprintk("--> %s\n", __func__);

		if (nfss->nfs_client->cl_devid_cache)
		pnfs_put_deviceid_cache(nfss->nfs_client);
		return 0;
		}

		/*
		* filelayout_check_layout()
		*
		* Make sure layout segment parameters are sane WRT the device.
		* At this point no generic layer initialization of the lseg has occurred,
		* and nothing has been added to the layout_hdr cache.
		*
		*/
		static int
		filelayout_check_layout(struct pnfs_layout_hdr *lo,
		struct nfs4_filelayout_segment *fl,
		struct nfs4_layoutget_res *lgr,
		struct nfs4_deviceid *id)
		{
		struct nfs4_file_layout_dsaddr *dsaddr;
		int status = -EINVAL;
		struct nfs_server *nfss = NFS_SERVER(lo->inode);

		dprintk("--> %s\n", __func__);

		if (fl->pattern_offset > lgr->range.offset) {
		dprintk("%s pattern_offset %lld to large\n",
		__func__, fl->pattern_offset);
		goto out;
		}

		if (fl->stripe_unit % PAGE_SIZE) {
		dprintk("%s Stripe unit (%u) not page aligned\n",
		__func__, fl->stripe_unit);
		goto out;
		}

		/* find and reference the deviceid */
		dsaddr = nfs4_fl_find_get_deviceid(nfss->nfs_client, id);
		if (dsaddr == NULL) {
		dsaddr = get_device_info(lo->inode, id);
		if (dsaddr == NULL)
		goto out;
		}
		fl->dsaddr = dsaddr;

		if (fl->first_stripe_index < 0 \|\|
		fl->first_stripe_index >= dsaddr->stripe_count) {
		dprintk("%s Bad first_stripe_index %d\n",
		__func__, fl->first_stripe_index);
		goto out_put;
		}

		if ((fl->stripe_type == STRIPE_SPARSE &&
		fl->num_fh > 1 && fl->num_fh != dsaddr->ds_num) \|\|
		(fl->stripe_type == STRIPE_DENSE &&
		fl->num_fh != dsaddr->stripe_count)) {
		dprintk("%s num_fh %u not valid for given packing\n",
		__func__, fl->num_fh);
		goto out_put;
		}

		if (fl->stripe_unit % nfss->rsize \|\| fl->stripe_unit % nfss->wsize) {
		dprintk("%s Stripe unit (%u) not aligned with rsize %u "
		"wsize %u\n", __func__, fl->stripe_unit, nfss->rsize,
		nfss->wsize);
		}

		status = 0;
		out:
		dprintk("--> %s returns %d\n", __func__, status);
		return status;
		out_put:
		pnfs_put_deviceid(nfss->nfs_client->cl_devid_cache, &dsaddr->deviceid);
		goto out;
		}

		static void filelayout_free_fh_array(struct nfs4_filelayout_segment *fl)
		{
		int i;

		for (i = 0; i < fl->num_fh; i++) {
		if (!fl->fh_array[i])
		break;
		kfree(fl->fh_array[i]);
		}
		kfree(fl->fh_array);
		fl->fh_array = NULL;
		}

		static void
		_filelayout_free_lseg(struct nfs4_filelayout_segment *fl)
		{
		filelayout_free_fh_array(fl);
		kfree(fl);
		}

		static int
		filelayout_decode_layout(struct pnfs_layout_hdr *flo,
		struct nfs4_filelayout_segment *fl,
		struct nfs4_layoutget_res *lgr,
		struct nfs4_deviceid *id)
		{
		uint32_t p = (uint32_t )lgr->layout.buf;
		uint32_t nfl_util;
		int i;

		dprintk("%s: set_layout_map Begin\n", __func__);

		memcpy(id, p, sizeof(*id));
		p += XDR_QUADLEN(NFS4_DEVICEID4_SIZE);
		print_deviceid(id);

		nfl_util = be32_to_cpup(p++);
		if (nfl_util & NFL4_UFLG_COMMIT_THRU_MDS)
		fl->commit_through_mds = 1;
		if (nfl_util & NFL4_UFLG_DENSE)
		fl->stripe_type = STRIPE_DENSE;
		else
		fl->stripe_type = STRIPE_SPARSE;
		fl->stripe_unit = nfl_util & ~NFL4_UFLG_MASK;

		fl->first_stripe_index = be32_to_cpup(p++);
		p = xdr_decode_hyper(p, &fl->pattern_offset);
		fl->num_fh = be32_to_cpup(p++);

		dprintk("%s: nfl_util 0x%X num_fh %u fsi %u po %llu\n",
		__func__, nfl_util, fl->num_fh, fl->first_stripe_index,
		fl->pattern_offset);

		fl->fh_array = kzalloc(fl->num_fh * sizeof(struct nfs_fh *),
		GFP_KERNEL);
		if (!fl->fh_array)
		return -ENOMEM;

		for (i = 0; i < fl->num_fh; i++) {
		/* Do we want to use a mempool here? */
		fl->fh_array[i] = kmalloc(sizeof(struct nfs_fh), GFP_KERNEL);
		if (!fl->fh_array[i]) {
		filelayout_free_fh_array(fl);
		return -ENOMEM;
		}
		fl->fh_array[i]->size = be32_to_cpup(p++);
		if (sizeof(struct nfs_fh) < fl->fh_array[i]->size) {
		printk(KERN_ERR "Too big fh %d received %d\n",
		i, fl->fh_array[i]->size);
		filelayout_free_fh_array(fl);
		return -EIO;
		}
		memcpy(fl->fh_array[i]->data, p, fl->fh_array[i]->size);
		p += XDR_QUADLEN(fl->fh_array[i]->size);
		dprintk("DEBUG: %s: fh len %d\n", __func__,
		fl->fh_array[i]->size);
		}

		return 0;
		}

		static struct pnfs_layout_segment *
		filelayout_alloc_lseg(struct pnfs_layout_hdr *layoutid,
		struct nfs4_layoutget_res *lgr)
		{
		struct nfs4_filelayout_segment *fl;
		int rc;
		struct nfs4_deviceid id;

		dprintk("--> %s\n", __func__);
		fl = kzalloc(sizeof(*fl), GFP_KERNEL);
		if (!fl)
		return NULL;

		rc = filelayout_decode_layout(layoutid, fl, lgr, &id);
		if (rc != 0 \|\| filelayout_check_layout(layoutid, fl, lgr, &id)) {
		_filelayout_free_lseg(fl);
		return NULL;
		}
		return &fl->generic_hdr;
		}

		static void
		filelayout_free_lseg(struct pnfs_layout_segment *lseg)
		{
		struct nfs_server *nfss = NFS_SERVER(lseg->layout->inode);
		struct nfs4_filelayout_segment *fl = FILELAYOUT_LSEG(lseg);

		dprintk("--> %s\n", __func__);
		pnfs_put_deviceid(nfss->nfs_client->cl_devid_cache,
		&fl->dsaddr->deviceid);
		_filelayout_free_lseg(fl);
		}

		static struct pnfs_layoutdriver_type filelayout_type = {
		.id = LAYOUT_NFSV4_1_FILES,
		.name = "LAYOUT_NFSV4_1_FILES",
		.owner = THIS_MODULE,
		.initialize_mountpoint = filelayout_initialize_mountpoint,
		.uninitialize_mountpoint = filelayout_uninitialize_mountpoint,
		.alloc_lseg = filelayout_alloc_lseg,
		.free_lseg = filelayout_free_lseg,
		};

		static int __init nfs4filelayout_init(void)

fs/nfs/nfs4filelayout.h

0 → 100644

+94 −0

Original line number	Diff line number	Diff line
		/*
		* NFSv4 file layout driver data structures.
		*
		* 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.
		*/

		#ifndef FS_NFS_NFS4FILELAYOUT_H
		#define FS_NFS_NFS4FILELAYOUT_H

		#include "pnfs.h"

		/*
		* Field testing shows we need to support upto 4096 stripe indices.
		* We store each index as a u8 (u32 on the wire) to keep the memory footprint
		* reasonable. This in turn means we support a maximum of 256
		* RFC 5661 multipath_list4 structures.
		*/
		#define NFS4_PNFS_MAX_STRIPE_CNT 4096
		#define NFS4_PNFS_MAX_MULTI_CNT 256 /* 256 fit into a u8 stripe_index */

		enum stripetype4 {
		STRIPE_SPARSE = 1,
		STRIPE_DENSE = 2
		};

		/* Individual ip address */
		struct nfs4_pnfs_ds {
		struct list_head ds_node; /* nfs4_pnfs_dev_hlist dev_dslist */
		u32 ds_ip_addr;
		u32 ds_port;
		struct nfs_client *ds_clp;
		atomic_t ds_count;
		};

		struct nfs4_file_layout_dsaddr {
		struct pnfs_deviceid_node deviceid;
		u32 stripe_count;
		u8 *stripe_indices;
		u32 ds_num;
		struct nfs4_pnfs_ds *ds_list[1];
		};

		struct nfs4_filelayout_segment {
		struct pnfs_layout_segment generic_hdr;
		u32 stripe_type;
		u32 commit_through_mds;
		u32 stripe_unit;
		u32 first_stripe_index;
		u64 pattern_offset;
		struct nfs4_file_layout_dsaddr dsaddr; / Point to GETDEVINFO data */
		unsigned int num_fh;
		struct nfs_fh **fh_array;
		};

		static inline struct nfs4_filelayout_segment *
		FILELAYOUT_LSEG(struct pnfs_layout_segment *lseg)
		{
		return container_of(lseg,
		struct nfs4_filelayout_segment,
		generic_hdr);
		}

		extern void nfs4_fl_free_deviceid_callback(struct pnfs_deviceid_node *);
		extern void print_ds(struct nfs4_pnfs_ds *ds);
		extern void print_deviceid(struct nfs4_deviceid *dev_id);
		extern struct nfs4_file_layout_dsaddr *
		nfs4_fl_find_get_deviceid(struct nfs_client , struct nfs4_deviceid dev_id);
		struct nfs4_file_layout_dsaddr *
		get_device_info(struct inode inode, struct nfs4_deviceid dev_id);

		#endif /* FS_NFS_NFS4FILELAYOUT_H */

fs/nfs/nfs4filelayoutdev.c

0 → 100644

+448 −0

Original line number	Diff line number	Diff line
		/*
		* Device operations for the pnfs nfs4 file layout driver.
		*
		* Copyright (c) 2002
		* The Regents of the University of Michigan
		* All Rights Reserved
		*
		* Dean Hildebrand <dhildebz@umich.edu>
		* Garth Goodson <Garth.Goodson@netapp.com>
		*
		* 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 <linux/vmalloc.h>

		#include "internal.h"
		#include "nfs4filelayout.h"

		#define NFSDBG_FACILITY NFSDBG_PNFS_LD

		/*
		* Data server cache
		*
		* Data servers can be mapped to different device ids.
		* nfs4_pnfs_ds reference counting
		* - set to 1 on allocation
		* - incremented when a device id maps a data server already in the cache.
		* - decremented when deviceid is removed from the cache.
		*/
		DEFINE_SPINLOCK(nfs4_ds_cache_lock);
		static LIST_HEAD(nfs4_data_server_cache);

		/* Debug routines */
		void
		print_ds(struct nfs4_pnfs_ds *ds)
		{
		if (ds == NULL) {
		printk("%s NULL device\n", __func__);
		return;
		}
		printk(" ip_addr %x port %hu\n"
		" ref count %d\n"
		" client %p\n"
		" cl_exchange_flags %x\n",
		ntohl(ds->ds_ip_addr), ntohs(ds->ds_port),
		atomic_read(&ds->ds_count), ds->ds_clp,
		ds->ds_clp ? ds->ds_clp->cl_exchange_flags : 0);
		}

		void
		print_ds_list(struct nfs4_file_layout_dsaddr *dsaddr)
		{
		int i;

		ifdebug(FACILITY) {
		printk("%s dsaddr->ds_num %d\n", __func__,
		dsaddr->ds_num);
		for (i = 0; i < dsaddr->ds_num; i++)
		print_ds(dsaddr->ds_list[i]);
		}
		}

		void print_deviceid(struct nfs4_deviceid *id)
		{
		u32 p = (u32 )id;

		dprintk("%s: device id= [%x%x%x%x]\n", __func__,
		p[0], p[1], p[2], p[3]);
		}

		/* nfs4_ds_cache_lock is held */
		static struct nfs4_pnfs_ds *
		_data_server_lookup_locked(u32 ip_addr, u32 port)
		{
		struct nfs4_pnfs_ds *ds;

		dprintk("_data_server_lookup: ip_addr=%x port=%hu\n",
		ntohl(ip_addr), ntohs(port));

		list_for_each_entry(ds, &nfs4_data_server_cache, ds_node) {
		if (ds->ds_ip_addr == ip_addr &&
		ds->ds_port == port) {
		return ds;
		}
		}
		return NULL;
		}

		static void
		destroy_ds(struct nfs4_pnfs_ds *ds)
		{
		dprintk("--> %s\n", __func__);
		ifdebug(FACILITY)
		print_ds(ds);

		if (ds->ds_clp)
		nfs_put_client(ds->ds_clp);
		kfree(ds);
		}

		static void
		nfs4_fl_free_deviceid(struct nfs4_file_layout_dsaddr *dsaddr)
		{
		struct nfs4_pnfs_ds *ds;
		int i;

		print_deviceid(&dsaddr->deviceid.de_id);

		for (i = 0; i < dsaddr->ds_num; i++) {
		ds = dsaddr->ds_list[i];
		if (ds != NULL) {
		if (atomic_dec_and_lock(&ds->ds_count,
		&nfs4_ds_cache_lock)) {
		list_del_init(&ds->ds_node);
		spin_unlock(&nfs4_ds_cache_lock);
		destroy_ds(ds);
		}
		}
		}
		kfree(dsaddr->stripe_indices);
		kfree(dsaddr);
		}

		void
		nfs4_fl_free_deviceid_callback(struct pnfs_deviceid_node *device)
		{
		struct nfs4_file_layout_dsaddr *dsaddr =
		container_of(device, struct nfs4_file_layout_dsaddr, deviceid);

		nfs4_fl_free_deviceid(dsaddr);
		}

		static struct nfs4_pnfs_ds *
		nfs4_pnfs_ds_add(struct inode *inode, u32 ip_addr, u32 port)
		{
		struct nfs4_pnfs_ds tmp_ds, ds;

		ds = kzalloc(sizeof(*tmp_ds), GFP_KERNEL);
		if (!ds)
		goto out;

		spin_lock(&nfs4_ds_cache_lock);
		tmp_ds = _data_server_lookup_locked(ip_addr, port);
		if (tmp_ds == NULL) {
		ds->ds_ip_addr = ip_addr;
		ds->ds_port = port;
		atomic_set(&ds->ds_count, 1);
		INIT_LIST_HEAD(&ds->ds_node);
		ds->ds_clp = NULL;
		list_add(&ds->ds_node, &nfs4_data_server_cache);
		dprintk("%s add new data server ip 0x%x\n", __func__,
		ds->ds_ip_addr);
		} else {
		kfree(ds);
		atomic_inc(&tmp_ds->ds_count);
		dprintk("%s data server found ip 0x%x, inc'ed ds_count to %d\n",
		__func__, tmp_ds->ds_ip_addr,
		atomic_read(&tmp_ds->ds_count));
		ds = tmp_ds;
		}
		spin_unlock(&nfs4_ds_cache_lock);
		out:
		return ds;
		}

		/*
		* Currently only support ipv4, and one multi-path address.
		*/
		static struct nfs4_pnfs_ds *
		decode_and_add_ds(__be32 *pp, struct inode inode)
		{
		struct nfs4_pnfs_ds *ds = NULL;
		char *buf;
		const char ipend, pstr;
		u32 ip_addr, port;
		int nlen, rlen, i;
		int tmp[2];
		__be32 r_netid, r_addr, p = pp;

		/* r_netid */
		nlen = be32_to_cpup(p++);
		r_netid = p;
		p += XDR_QUADLEN(nlen);

		/* r_addr */
		rlen = be32_to_cpup(p++);
		r_addr = p;
		p += XDR_QUADLEN(rlen);
		*pp = p;

		/* Check that netid is "tcp" */
		if (nlen != 3 \|\| memcmp((char *)r_netid, "tcp", 3)) {
		dprintk("%s: ERROR: non ipv4 TCP r_netid\n", __func__);
		goto out_err;
		}

		/* ipv6 length plus port is legal */
		if (rlen > INET6_ADDRSTRLEN + 8) {
		dprintk("%s Invalid address, length %d\n", __func__,
		rlen);
		goto out_err;
		}
		buf = kmalloc(rlen + 1, GFP_KERNEL);
		buf[rlen] = '\0';
		memcpy(buf, r_addr, rlen);

		/* replace the port dots with dashes for the in4_pton() delimiter*/
		for (i = 0; i < 2; i++) {
		char *res = strrchr(buf, '.');
		*res = '-';
		}

		/* Currently only support ipv4 address */
		if (in4_pton(buf, rlen, (u8 *)&ip_addr, '-', &ipend) == 0) {
		dprintk("%s: Only ipv4 addresses supported\n", __func__);
		goto out_free;
		}

		/* port */
		pstr = ipend;
		sscanf(pstr, "-%d-%d", &tmp[0], &tmp[1]);
		port = htons((tmp[0] << 8) \| (tmp[1]));

		ds = nfs4_pnfs_ds_add(inode, ip_addr, port);
		dprintk("%s Decoded address and port %s\n", __func__, buf);
		out_free:
		kfree(buf);
		out_err:
		return ds;
		}

		/* Decode opaque device data and return the result */
		static struct nfs4_file_layout_dsaddr*
		decode_device(struct inode ino, struct pnfs_device pdev)
		{
		int i, dummy;
		u32 cnt, num;
		u8 *indexp;
		__be32 p = (__be32 )pdev->area, *indicesp;
		struct nfs4_file_layout_dsaddr *dsaddr;

		/* Get the stripe count (number of stripe index) */
		cnt = be32_to_cpup(p++);
		dprintk("%s stripe count %d\n", __func__, cnt);
		if (cnt > NFS4_PNFS_MAX_STRIPE_CNT) {
		printk(KERN_WARNING "%s: stripe count %d greater than "
		"supported maximum %d\n", __func__,
		cnt, NFS4_PNFS_MAX_STRIPE_CNT);
		goto out_err;
		}

		/* Check the multipath list count */
		indicesp = p;
		p += XDR_QUADLEN(cnt << 2);
		num = be32_to_cpup(p++);
		dprintk("%s ds_num %u\n", __func__, num);
		if (num > NFS4_PNFS_MAX_MULTI_CNT) {
		printk(KERN_WARNING "%s: multipath count %d greater than "
		"supported maximum %d\n", __func__,
		num, NFS4_PNFS_MAX_MULTI_CNT);
		goto out_err;
		}
		dsaddr = kzalloc(sizeof(*dsaddr) +
		(sizeof(struct nfs4_pnfs_ds ) (num - 1)),
		GFP_KERNEL);
		if (!dsaddr)
		goto out_err;

		dsaddr->stripe_indices = kzalloc(sizeof(u8) * cnt, GFP_KERNEL);
		if (!dsaddr->stripe_indices)
		goto out_err_free;

		dsaddr->stripe_count = cnt;
		dsaddr->ds_num = num;

		memcpy(&dsaddr->deviceid.de_id, &pdev->dev_id, sizeof(pdev->dev_id));

		/* Go back an read stripe indices */
		p = indicesp;
		indexp = &dsaddr->stripe_indices[0];
		for (i = 0; i < dsaddr->stripe_count; i++) {
		*indexp = be32_to_cpup(p++);
		if (*indexp >= num)
		goto out_err_free;
		indexp++;
		}
		/* Skip already read multipath list count */
		p++;

		for (i = 0; i < dsaddr->ds_num; i++) {
		int j;

		dummy = be32_to_cpup(p++); /* multipath count */
		if (dummy > 1) {
		printk(KERN_WARNING
		"%s: Multipath count %d not supported, "
		"skipping all greater than 1\n", __func__,
		dummy);
		}
		for (j = 0; j < dummy; j++) {
		if (j == 0) {
		dsaddr->ds_list[i] = decode_and_add_ds(&p, ino);
		if (dsaddr->ds_list[i] == NULL)
		goto out_err_free;
		} else {
		u32 len;
		/* skip extra multipath */
		len = be32_to_cpup(p++);
		p += XDR_QUADLEN(len);
		len = be32_to_cpup(p++);
		p += XDR_QUADLEN(len);
		continue;
		}
		}
		}
		return dsaddr;

		out_err_free:
		nfs4_fl_free_deviceid(dsaddr);
		out_err:
		dprintk("%s ERROR: returning NULL\n", __func__);
		return NULL;
		}

		/*
		* Decode the opaque device specified in 'dev'
		* and add it to the list of available devices.
		* If the deviceid is already cached, nfs4_add_deviceid will return
		* a pointer to the cached struct and throw away the new.
		*/
		static struct nfs4_file_layout_dsaddr*
		decode_and_add_device(struct inode inode, struct pnfs_device dev)
		{
		struct nfs4_file_layout_dsaddr *dsaddr;
		struct pnfs_deviceid_node *d;

		dsaddr = decode_device(inode, dev);
		if (!dsaddr) {
		printk(KERN_WARNING "%s: Could not decode or add device\n",
		__func__);
		return NULL;
		}

		d = pnfs_add_deviceid(NFS_SERVER(inode)->nfs_client->cl_devid_cache,
		&dsaddr->deviceid);

		return container_of(d, struct nfs4_file_layout_dsaddr, deviceid);
		}

		/*
		* Retrieve the information for dev_id, add it to the list
		* of available devices, and return it.
		*/
		struct nfs4_file_layout_dsaddr *
		get_device_info(struct inode inode, struct nfs4_deviceid dev_id)
		{
		struct pnfs_device *pdev = NULL;
		u32 max_resp_sz;
		int max_pages;
		struct page **pages = NULL;
		struct nfs4_file_layout_dsaddr *dsaddr = NULL;
		int rc, i;
		struct nfs_server *server = NFS_SERVER(inode);

		/*
		* Use the session max response size as the basis for setting
		* GETDEVICEINFO's maxcount
		*/
		max_resp_sz = server->nfs_client->cl_session->fc_attrs.max_resp_sz;
		max_pages = max_resp_sz >> PAGE_SHIFT;
		dprintk("%s inode %p max_resp_sz %u max_pages %d\n",
		__func__, inode, max_resp_sz, max_pages);

		pdev = kzalloc(sizeof(struct pnfs_device), GFP_KERNEL);
		if (pdev == NULL)
		return NULL;

		pages = kzalloc(max_pages * sizeof(struct page *), GFP_KERNEL);
		if (pages == NULL) {
		kfree(pdev);
		return NULL;
		}
		for (i = 0; i < max_pages; i++) {
		pages[i] = alloc_page(GFP_KERNEL);
		if (!pages[i])
		goto out_free;
		}

		/* set pdev->area */
		pdev->area = vmap(pages, max_pages, VM_MAP, PAGE_KERNEL);
		if (!pdev->area)
		goto out_free;

		memcpy(&pdev->dev_id, dev_id, sizeof(*dev_id));
		pdev->layout_type = LAYOUT_NFSV4_1_FILES;
		pdev->pages = pages;
		pdev->pgbase = 0;
		pdev->pglen = PAGE_SIZE * max_pages;
		pdev->mincount = 0;

		rc = nfs4_proc_getdeviceinfo(server, pdev);
		dprintk("%s getdevice info returns %d\n", __func__, rc);
		if (rc)
		goto out_free;

		/*
		* Found new device, need to decode it and then add it to the
		* list of known devices for this mountpoint.
		*/
		dsaddr = decode_and_add_device(inode, pdev);
		out_free:
		if (pdev->area != NULL)
		vunmap(pdev->area);
		for (i = 0; i < max_pages; i++)
		__free_page(pages[i]);
		kfree(pages);
		kfree(pdev);
		dprintk("<-- %s dsaddr %p\n", __func__, dsaddr);
		return dsaddr;
		}

		struct nfs4_file_layout_dsaddr *
		nfs4_fl_find_get_deviceid(struct nfs_client clp, struct nfs4_deviceid id)
		{
		struct pnfs_deviceid_node *d;

		d = pnfs_find_get_deviceid(clp->cl_devid_cache, id);
		return (d == NULL) ? NULL :
		container_of(d, struct nfs4_file_layout_dsaddr, deviceid);
		}

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