/*
   *  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
  ", __func__);
  		return;
  	}

  	printk("        ds %s
  "

  		"        ref count %d
  "
  		"        client %p
  "
  		"        cl_exchange_flags %x
  ",

  		ds->ds_remotestr,

  		atomic_read(&ds->ds_count), ds->ds_clp,
  		ds->ds_clp ? ds->ds_clp->cl_exchange_flags : 0);
  }

  static bool
  same_sockaddr(struct sockaddr *addr1, struct sockaddr *addr2)

  {

  	struct sockaddr_in *a, *b;
  	struct sockaddr_in6 *a6, *b6;

  	if (addr1->sa_family != addr2->sa_family)
  		return false;
  
  	switch (addr1->sa_family) {
  	case AF_INET:
  		a = (struct sockaddr_in *)addr1;
  		b = (struct sockaddr_in *)addr2;
  
  		if (a->sin_addr.s_addr == b->sin_addr.s_addr &&
  		    a->sin_port == b->sin_port)
  			return true;
  		break;
  
  	case AF_INET6:
  		a6 = (struct sockaddr_in6 *)addr1;
  		b6 = (struct sockaddr_in6 *)addr2;
  
  		/* LINKLOCAL addresses must have matching scope_id */
  		if (ipv6_addr_scope(&a6->sin6_addr) ==
  		    IPV6_ADDR_SCOPE_LINKLOCAL &&
  		    a6->sin6_scope_id != b6->sin6_scope_id)
  			return false;
  
  		if (ipv6_addr_equal(&a6->sin6_addr, &b6->sin6_addr) &&
  		    a6->sin6_port == b6->sin6_port)
  			return true;
  		break;
  
  	default:
  		dprintk("%s: unhandled address family: %u
  ",
  			__func__, addr1->sa_family);
  		return false;
  	}
  
  	return false;
  }
  
  /*
   * Lookup DS by addresses.  The first matching address returns true.
   * nfs4_ds_cache_lock is held
   */
  static struct nfs4_pnfs_ds *
  _data_server_lookup_locked(struct list_head *dsaddrs)
  {
  	struct nfs4_pnfs_ds *ds;
  	struct nfs4_pnfs_ds_addr *da1, *da2;
  
  	list_for_each_entry(da1, dsaddrs, da_node) {
  		list_for_each_entry(ds, &nfs4_data_server_cache, ds_node) {
  			list_for_each_entry(da2, &ds->ds_addrs, da_node) {
  				if (same_sockaddr(
  					(struct sockaddr *)&da1->da_addr,
  					(struct sockaddr *)&da2->da_addr))
  					return ds;
  			}

  		}
  	}
  	return NULL;
  }

  /*

   * Compare two lists of addresses.
   */
  static bool
  _data_server_match_all_addrs_locked(struct list_head *dsaddrs1,
  				    struct list_head *dsaddrs2)
  {
  	struct nfs4_pnfs_ds_addr *da1, *da2;
  	size_t count1 = 0,
  	       count2 = 0;
  
  	list_for_each_entry(da1, dsaddrs1, da_node)
  		count1++;
  
  	list_for_each_entry(da2, dsaddrs2, da_node) {
  		bool found = false;
  		count2++;
  		list_for_each_entry(da1, dsaddrs1, da_node) {
  			if (same_sockaddr((struct sockaddr *)&da1->da_addr,
  				(struct sockaddr *)&da2->da_addr)) {
  				found = true;
  				break;
  			}
  		}
  		if (!found)
  			return false;
  	}
  
  	return (count1 == count2);
  }
  
  /*

   * Create an rpc connection to the nfs4_pnfs_ds data server

   * Currently only supports IPv4 and IPv6 addresses

   */
  static int
  nfs4_ds_connect(struct nfs_server *mds_srv, struct nfs4_pnfs_ds *ds)
  {

  	struct nfs_client *clp = ERR_PTR(-EIO);

  	struct nfs4_pnfs_ds_addr *da;

  	int status = 0;

  	dprintk("--> %s DS %s au_flavor %d
  ", __func__, ds->ds_remotestr,

  		mds_srv->nfs_client->cl_rpcclient->cl_auth->au_flavor);

  	BUG_ON(list_empty(&ds->ds_addrs));

  	list_for_each_entry(da, &ds->ds_addrs, da_node) {
  		dprintk("%s: DS %s: trying address %s
  ",
  			__func__, ds->ds_remotestr, da->da_remotestr);

  		clp = nfs4_set_ds_client(mds_srv->nfs_client,

  				 (struct sockaddr *)&da->da_addr,
  				 da->da_addrlen, IPPROTO_TCP);

  		if (!IS_ERR(clp))
  			break;
  	}

  	if (IS_ERR(clp)) {
  		status = PTR_ERR(clp);
  		goto out;
  	}
  
  	if ((clp->cl_exchange_flags & EXCHGID4_FLAG_MASK_PNFS) != 0) {
  		if (!is_ds_client(clp)) {
  			status = -ENODEV;
  			goto out_put;
  		}
  		ds->ds_clp = clp;

  		dprintk("%s [existing] server=%s
  ", __func__,
  			ds->ds_remotestr);

  		goto out;
  	}
  
  	/*
  	 * Do not set NFS_CS_CHECK_LEASE_TIME instead set the DS lease to
  	 * be equal to the MDS lease. Renewal is scheduled in create_session.
  	 */
  	spin_lock(&mds_srv->nfs_client->cl_lock);
  	clp->cl_lease_time = mds_srv->nfs_client->cl_lease_time;
  	spin_unlock(&mds_srv->nfs_client->cl_lock);
  	clp->cl_last_renewal = jiffies;
  
  	/* New nfs_client */
  	status = nfs4_init_ds_session(clp);
  	if (status)
  		goto out_put;
  
  	ds->ds_clp = clp;

  	dprintk("%s [new] addr: %s
  ", __func__, ds->ds_remotestr);

  out:
  	return status;
  out_put:
  	nfs_put_client(clp);
  	goto out;
  }

  static void
  destroy_ds(struct nfs4_pnfs_ds *ds)
  {

  	struct nfs4_pnfs_ds_addr *da;

  	dprintk("--> %s
  ", __func__);
  	ifdebug(FACILITY)
  		print_ds(ds);
  
  	if (ds->ds_clp)
  		nfs_put_client(ds->ds_clp);

  
  	while (!list_empty(&ds->ds_addrs)) {
  		da = list_first_entry(&ds->ds_addrs,
  				      struct nfs4_pnfs_ds_addr,
  				      da_node);
  		list_del_init(&da->da_node);
  		kfree(da->da_remotestr);
  		kfree(da);
  	}

  	kfree(ds->ds_remotestr);

  	kfree(ds);
  }

  void

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

  	nfs4_print_deviceid(&dsaddr->id_node.deviceid);

  
  	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);
  }

  /*
   * Create a string with a human readable address and port to avoid
   * complicated setup around many dprinks.
   */
  static char *

  nfs4_pnfs_remotestr(struct list_head *dsaddrs, gfp_t gfp_flags)

  {

  	struct nfs4_pnfs_ds_addr *da;

  	char *remotestr;

  	size_t len;

  	char *p;

  	len = 3;        /* '{', '}' and eol */
  	list_for_each_entry(da, dsaddrs, da_node) {
  		len += strlen(da->da_remotestr) + 1;    /* string plus comma */

  	}

  	remotestr = kzalloc(len, gfp_flags);
  	if (!remotestr)

  		return NULL;

  	p = remotestr;
  	*(p++) = '{';
  	len--;
  	list_for_each_entry(da, dsaddrs, da_node) {
  		size_t ll = strlen(da->da_remotestr);

  		if (ll > len)
  			goto out_err;

  		memcpy(p, da->da_remotestr, ll);
  		p += ll;
  		len -= ll;

  		if (len < 1)
  			goto out_err;
  		(*p++) = ',';
  		len--;
  	}
  	if (len < 2)
  		goto out_err;
  	*(p++) = '}';
  	*p = '\0';

  	return remotestr;

  out_err:
  	kfree(remotestr);
  	return NULL;

  }

  static struct nfs4_pnfs_ds *

  nfs4_pnfs_ds_add(struct list_head *dsaddrs, gfp_t gfp_flags)

  {

  	struct nfs4_pnfs_ds *tmp_ds, *ds = NULL;
  	char *remotestr;

  	if (list_empty(dsaddrs)) {
  		dprintk("%s: no addresses defined
  ", __func__);
  		goto out;
  	}
  
  	ds = kzalloc(sizeof(*ds), gfp_flags);

  	if (!ds)
  		goto out;

  	/* this is only used for debugging, so it's ok if its NULL */

  	remotestr = nfs4_pnfs_remotestr(dsaddrs, gfp_flags);

  	spin_lock(&nfs4_ds_cache_lock);

  	tmp_ds = _data_server_lookup_locked(dsaddrs);

  	if (tmp_ds == NULL) {

  		INIT_LIST_HEAD(&ds->ds_addrs);
  		list_splice_init(dsaddrs, &ds->ds_addrs);

  		ds->ds_remotestr = remotestr;

  		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 %s
  ", __func__,
  			ds->ds_remotestr);

  	} else {

  		if (!_data_server_match_all_addrs_locked(&tmp_ds->ds_addrs,
  							 dsaddrs)) {
  			dprintk("%s:  multipath address mismatch: %s != %s",
  				__func__, tmp_ds->ds_remotestr, remotestr);
  		}

  		kfree(remotestr);

  		kfree(ds);
  		atomic_inc(&tmp_ds->ds_count);

  		dprintk("%s data server %s found, inc'ed ds_count to %d
  ",
  			__func__, tmp_ds->ds_remotestr,

  			atomic_read(&tmp_ds->ds_count));
  		ds = tmp_ds;
  	}
  	spin_unlock(&nfs4_ds_cache_lock);
  out:
  	return ds;
  }
  
  /*

   * Currently only supports ipv4, ipv6 and one multi-path address.

   */

  static struct nfs4_pnfs_ds_addr *
  decode_ds_addr(struct xdr_stream *streamp, gfp_t gfp_flags)

  {

  	struct nfs4_pnfs_ds_addr *da = NULL;

  	char *buf, *portstr;

  	__be16 port;

  	int nlen, rlen;

  	int tmp[2];

  	__be32 *p;

  	char *netid, *match_netid;

  	size_t len, match_netid_len;
  	char *startsep = "";
  	char *endsep = "";

  
  	/* r_netid */

  	p = xdr_inline_decode(streamp, 4);
  	if (unlikely(!p))
  		goto out_err;

  	nlen = be32_to_cpup(p++);

  	p = xdr_inline_decode(streamp, nlen);
  	if (unlikely(!p))
  		goto out_err;

  	netid = kmalloc(nlen+1, gfp_flags);
  	if (unlikely(!netid))

  		goto out_err;

  	netid[nlen] = '\0';
  	memcpy(netid, p, nlen);
  
  	/* r_addr: ip/ip6addr with port in dec octets - see RFC 5665 */

  	p = xdr_inline_decode(streamp, 4);
  	if (unlikely(!p))

  		goto out_free_netid;

  	rlen = be32_to_cpup(p);
  
  	p = xdr_inline_decode(streamp, rlen);
  	if (unlikely(!p))

  		goto out_free_netid;

  	/* port is ".ABC.DEF", 8 chars max */
  	if (rlen > INET6_ADDRSTRLEN + IPV6_SCOPE_ID_LEN + 8) {

  		dprintk("%s: Invalid address, length %d
  ", __func__,

  			rlen);

  		goto out_free_netid;

  	}

  	buf = kmalloc(rlen + 1, gfp_flags);

  	if (!buf) {
  		dprintk("%s: Not enough memory
  ", __func__);

  		goto out_free_netid;

  	}

  	buf[rlen] = '\0';

  	memcpy(buf, p, rlen);

  	/* replace port '.' with '-' */
  	portstr = strrchr(buf, '.');
  	if (!portstr) {
  		dprintk("%s: Failed finding expected dot in port
  ",
  			__func__);
  		goto out_free_buf;
  	}
  	*portstr = '-';
  
  	/* find '.' between address and port */
  	portstr = strrchr(buf, '.');
  	if (!portstr) {
  		dprintk("%s: Failed finding expected dot between address and "
  			"port
  ", __func__);
  		goto out_free_buf;

  	}

  	*portstr = '\0';

  	da = kzalloc(sizeof(*da), gfp_flags);
  	if (unlikely(!da))

  		goto out_free_buf;

  
  	INIT_LIST_HEAD(&da->da_node);
  
  	if (!rpc_pton(buf, portstr-buf, (struct sockaddr *)&da->da_addr,
  		      sizeof(da->da_addr))) {
  		dprintk("%s: error parsing address %s
  ", __func__, buf);
  		goto out_free_da;

  	}

  	portstr++;
  	sscanf(portstr, "%d-%d", &tmp[0], &tmp[1]);

  	port = htons((tmp[0] << 8) | (tmp[1]));

  	switch (da->da_addr.ss_family) {

  	case AF_INET:

  		((struct sockaddr_in *)&da->da_addr)->sin_port = port;
  		da->da_addrlen = sizeof(struct sockaddr_in);

  		match_netid = "tcp";
  		match_netid_len = 3;
  		break;
  
  	case AF_INET6:

  		((struct sockaddr_in6 *)&da->da_addr)->sin6_port = port;
  		da->da_addrlen = sizeof(struct sockaddr_in6);

  		match_netid = "tcp6";
  		match_netid_len = 4;

  		startsep = "[";
  		endsep = "]";

  		break;
  
  	default:
  		dprintk("%s: unsupported address family: %u
  ",

  			__func__, da->da_addr.ss_family);
  		goto out_free_da;

  	}
  
  	if (nlen != match_netid_len || strncmp(netid, match_netid, nlen)) {
  		dprintk("%s: ERROR: r_netid \"%s\" != \"%s\"
  ",
  			__func__, netid, match_netid);

  		goto out_free_da;

  	}

  	/* save human readable address */
  	len = strlen(startsep) + strlen(buf) + strlen(endsep) + 7;
  	da->da_remotestr = kzalloc(len, gfp_flags);
  
  	/* NULL is ok, only used for dprintk */
  	if (da->da_remotestr)
  		snprintf(da->da_remotestr, len, "%s%s%s:%u", startsep,
  			 buf, endsep, ntohs(port));
  
  	dprintk("%s: Parsed DS addr %s
  ", __func__, da->da_remotestr);
  	kfree(buf);
  	kfree(netid);
  	return da;
  
  out_free_da:
  	kfree(da);

  out_free_buf:

  	dprintk("%s: Error parsing DS addr: %s
  ", __func__, buf);

  	kfree(buf);

  out_free_netid:
  	kfree(netid);

  out_err:

  	return NULL;

  }
  
  /* Decode opaque device data and return the result */
  static struct nfs4_file_layout_dsaddr*

  decode_device(struct inode *ino, struct pnfs_device *pdev, gfp_t gfp_flags)

  {

  	int i;

  	u32 cnt, num;
  	u8 *indexp;

  	__be32 *p;
  	u8 *stripe_indices;
  	u8 max_stripe_index;
  	struct nfs4_file_layout_dsaddr *dsaddr = NULL;
  	struct xdr_stream stream;

  	struct xdr_buf buf;

  	struct page *scratch;

  	struct list_head dsaddrs;
  	struct nfs4_pnfs_ds_addr *da;

  
  	/* set up xdr stream */

  	scratch = alloc_page(gfp_flags);

  	if (!scratch)
  		goto out_err;

  	xdr_init_decode_pages(&stream, &buf, pdev->pages, pdev->pglen);

  	xdr_set_scratch_buffer(&stream, page_address(scratch), PAGE_SIZE);

  
  	/* Get the stripe count (number of stripe index) */

  	p = xdr_inline_decode(&stream, 4);
  	if (unlikely(!p))
  		goto out_err_free_scratch;
  
  	cnt = be32_to_cpup(p);

  	dprintk("%s stripe count  %d
  ", __func__, cnt);
  	if (cnt > NFS4_PNFS_MAX_STRIPE_CNT) {
  		printk(KERN_WARNING "%s: stripe count %d greater than "
  		       "supported maximum %d
  ", __func__,
  			cnt, NFS4_PNFS_MAX_STRIPE_CNT);

  		goto out_err_free_scratch;
  	}
  
  	/* read stripe indices */

  	stripe_indices = kcalloc(cnt, sizeof(u8), gfp_flags);

  	if (!stripe_indices)
  		goto out_err_free_scratch;
  
  	p = xdr_inline_decode(&stream, cnt << 2);
  	if (unlikely(!p))
  		goto out_err_free_stripe_indices;
  
  	indexp = &stripe_indices[0];
  	max_stripe_index = 0;
  	for (i = 0; i < cnt; i++) {
  		*indexp = be32_to_cpup(p++);
  		max_stripe_index = max(max_stripe_index, *indexp);
  		indexp++;

  	}
  
  	/* Check the multipath list count */

  	p = xdr_inline_decode(&stream, 4);
  	if (unlikely(!p))
  		goto out_err_free_stripe_indices;
  
  	num = be32_to_cpup(p);

  	dprintk("%s ds_num %u
  ", __func__, num);
  	if (num > NFS4_PNFS_MAX_MULTI_CNT) {
  		printk(KERN_WARNING "%s: multipath count %d greater than "
  			"supported maximum %d
  ", __func__,
  			num, NFS4_PNFS_MAX_MULTI_CNT);

  		goto out_err_free_stripe_indices;

  	}

  
  	/* validate stripe indices are all < num */
  	if (max_stripe_index >= num) {
  		printk(KERN_WARNING "%s: stripe index %u >= num ds %u
  ",
  			__func__, max_stripe_index, num);
  		goto out_err_free_stripe_indices;
  	}

  	dsaddr = kzalloc(sizeof(*dsaddr) +
  			(sizeof(struct nfs4_pnfs_ds *) * (num - 1)),

  			gfp_flags);

  	if (!dsaddr)

  		goto out_err_free_stripe_indices;

  
  	dsaddr->stripe_count = cnt;

  	dsaddr->stripe_indices = stripe_indices;
  	stripe_indices = NULL;

  	dsaddr->ds_num = num;

  	nfs4_init_deviceid_node(&dsaddr->id_node,
  				NFS_SERVER(ino)->pnfs_curr_ld,
  				NFS_SERVER(ino)->nfs_client,

  				&pdev->dev_id);

  	INIT_LIST_HEAD(&dsaddrs);

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

  		u32 mp_count;
  
  		p = xdr_inline_decode(&stream, 4);
  		if (unlikely(!p))
  			goto out_err_free_deviceid;

  		mp_count = be32_to_cpup(p); /* multipath count */

  		for (j = 0; j < mp_count; j++) {

  			da = decode_ds_addr(&stream, gfp_flags);
  			if (da)
  				list_add_tail(&da->da_node, &dsaddrs);
  		}
  		if (list_empty(&dsaddrs)) {
  			dprintk("%s: no suitable DS addresses found
  ",
  				__func__);
  			goto out_err_free_deviceid;
  		}
  
  		dsaddr->ds_list[i] = nfs4_pnfs_ds_add(&dsaddrs, gfp_flags);
  		if (!dsaddr->ds_list[i])
  			goto out_err_drain_dsaddrs;
  
  		/* If DS was already in cache, free ds addrs */
  		while (!list_empty(&dsaddrs)) {
  			da = list_first_entry(&dsaddrs,
  					      struct nfs4_pnfs_ds_addr,
  					      da_node);
  			list_del_init(&da->da_node);
  			kfree(da->da_remotestr);
  			kfree(da);

  		}
  	}

  
  	__free_page(scratch);

  	return dsaddr;

  out_err_drain_dsaddrs:
  	while (!list_empty(&dsaddrs)) {
  		da = list_first_entry(&dsaddrs, struct nfs4_pnfs_ds_addr,
  				      da_node);
  		list_del_init(&da->da_node);
  		kfree(da->da_remotestr);
  		kfree(da);
  	}

  out_err_free_deviceid:

  	nfs4_fl_free_deviceid(dsaddr);

  	/* stripe_indicies was part of dsaddr */
  	goto out_err_free_scratch;
  out_err_free_stripe_indices:
  	kfree(stripe_indices);
  out_err_free_scratch:
  	__free_page(scratch);

  out_err:
  	dprintk("%s ERROR: returning NULL
  ", __func__);
  	return NULL;
  }
  
  /*

   * Decode the opaque device specified in 'dev' and add it to the cache of
   * available devices.

   */

  static struct nfs4_file_layout_dsaddr *

  decode_and_add_device(struct inode *inode, struct pnfs_device *dev, gfp_t gfp_flags)

  {

  	struct nfs4_deviceid_node *d;
  	struct nfs4_file_layout_dsaddr *n, *new;

  	new = decode_device(inode, dev, gfp_flags);

  	if (!new) {

  		printk(KERN_WARNING "%s: Could not decode or add device
  ",
  			__func__);
  		return NULL;
  	}

  	d = nfs4_insert_deviceid_node(&new->id_node);
  	n = container_of(d, struct nfs4_file_layout_dsaddr, id_node);
  	if (n != new) {

  		nfs4_fl_free_deviceid(new);

  		return n;

  	}

  	return new;

  }
  
  /*
   * 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, gfp_t gfp_flags)

  {
  	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
  ",
  		__func__, inode, max_resp_sz, max_pages);

  	pdev = kzalloc(sizeof(struct pnfs_device), gfp_flags);

  	if (pdev == NULL)
  		return NULL;

  	pages = kzalloc(max_pages * sizeof(struct page *), gfp_flags);

  	if (pages == NULL) {
  		kfree(pdev);
  		return NULL;
  	}
  	for (i = 0; i < max_pages; i++) {

  		pages[i] = alloc_page(gfp_flags);

  		if (!pages[i])
  			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
  ", __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, gfp_flags);

  out_free:

  	for (i = 0; i < max_pages; i++)
  		__free_page(pages[i]);
  	kfree(pages);
  	kfree(pdev);
  	dprintk("<-- %s dsaddr %p
  ", __func__, dsaddr);
  	return dsaddr;
  }

  void
  nfs4_fl_put_deviceid(struct nfs4_file_layout_dsaddr *dsaddr)

  {

  	nfs4_put_deviceid_node(&dsaddr->id_node);

  }

  
  /*
   * Want res = (offset - layout->pattern_offset)/ layout->stripe_unit
   * Then: ((res + fsi) % dsaddr->stripe_count)
   */
  u32
  nfs4_fl_calc_j_index(struct pnfs_layout_segment *lseg, loff_t offset)
  {
  	struct nfs4_filelayout_segment *flseg = FILELAYOUT_LSEG(lseg);
  	u64 tmp;
  
  	tmp = offset - flseg->pattern_offset;
  	do_div(tmp, flseg->stripe_unit);
  	tmp += flseg->first_stripe_index;
  	return do_div(tmp, flseg->dsaddr->stripe_count);
  }
  
  u32
  nfs4_fl_calc_ds_index(struct pnfs_layout_segment *lseg, u32 j)
  {
  	return FILELAYOUT_LSEG(lseg)->dsaddr->stripe_indices[j];
  }
  
  struct nfs_fh *
  nfs4_fl_select_ds_fh(struct pnfs_layout_segment *lseg, u32 j)
  {
  	struct nfs4_filelayout_segment *flseg = FILELAYOUT_LSEG(lseg);
  	u32 i;
  
  	if (flseg->stripe_type == STRIPE_SPARSE) {
  		if (flseg->num_fh == 1)
  			i = 0;
  		else if (flseg->num_fh == 0)
  			/* Use the MDS OPEN fh set in nfs_read_rpcsetup */
  			return NULL;
  		else
  			i = nfs4_fl_calc_ds_index(lseg, j);
  	} else
  		i = j;
  	return flseg->fh_array[i];
  }

  static void
  filelayout_mark_devid_negative(struct nfs4_file_layout_dsaddr *dsaddr,

  			       int err, const char *ds_remotestr)

  {

  	u32 *p = (u32 *)&dsaddr->id_node.deviceid;

  	printk(KERN_ERR "NFS: data server %s connection error %d."

  		" Deviceid [%x%x%x%x] marked out of use.
  ",

  		ds_remotestr, err, p[0], p[1], p[2], p[3]);

  	spin_lock(&nfs4_ds_cache_lock);

  	dsaddr->flags |= NFS4_DEVICE_ID_NEG_ENTRY;

  	spin_unlock(&nfs4_ds_cache_lock);

  }

  struct nfs4_pnfs_ds *
  nfs4_fl_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx)
  {
  	struct nfs4_file_layout_dsaddr *dsaddr = FILELAYOUT_LSEG(lseg)->dsaddr;
  	struct nfs4_pnfs_ds *ds = dsaddr->ds_list[ds_idx];
  
  	if (ds == NULL) {
  		printk(KERN_ERR "%s: No data server for offset index %d
  ",
  			__func__, ds_idx);
  		return NULL;
  	}
  
  	if (!ds->ds_clp) {

  		struct nfs_server *s = NFS_SERVER(lseg->pls_layout->plh_inode);

  		int err;

  		if (dsaddr->flags & NFS4_DEVICE_ID_NEG_ENTRY) {
  			/* Already tried to connect, don't try again */
  			dprintk("%s Deviceid marked out of use
  ", __func__);
  			return NULL;
  		}
  		err = nfs4_ds_connect(s, ds);

  		if (err) {

  			filelayout_mark_devid_negative(dsaddr, err,

  						       ds->ds_remotestr);

  			return NULL;
  		}
  	}
  	return ds;
  }