// SPDX-License-Identifier: GPL-2.0-only

  /*
   * Common NFS I/O  operations for the pnfs file based
   * layout drivers.
   *
   * Copyright (c) 2014, Primary Data, Inc. All rights reserved.
   *
   * Tom Haynes <loghyr@primarydata.com>
   */
  
  #include <linux/nfs_fs.h>
  #include <linux/nfs_page.h>

  #include <linux/sunrpc/addr.h>

  #include <linux/module.h>

  #include "nfs4session.h"

  #include "internal.h"
  #include "pnfs.h"

  #define NFSDBG_FACILITY		NFSDBG_PNFS

  void pnfs_generic_rw_release(void *data)
  {
  	struct nfs_pgio_header *hdr = data;

  	nfs_put_client(hdr->ds_clp);
  	hdr->mds_ops->rpc_release(data);
  }
  EXPORT_SYMBOL_GPL(pnfs_generic_rw_release);
  
  /* Fake up some data that will cause nfs_commit_release to retry the writes. */
  void pnfs_generic_prepare_to_resend_writes(struct nfs_commit_data *data)
  {

  	struct nfs_writeverf *verf = data->res.verf;

  
  	data->task.tk_status = 0;

  	memset(&verf->verifier, 0, sizeof(verf->verifier));
  	verf->committed = NFS_UNSTABLE;

  }
  EXPORT_SYMBOL_GPL(pnfs_generic_prepare_to_resend_writes);
  
  void pnfs_generic_write_commit_done(struct rpc_task *task, void *data)
  {
  	struct nfs_commit_data *wdata = data;
  
  	/* Note this may cause RPC to be resent */
  	wdata->mds_ops->rpc_call_done(task, data);
  }
  EXPORT_SYMBOL_GPL(pnfs_generic_write_commit_done);
  
  void pnfs_generic_commit_release(void *calldata)
  {
  	struct nfs_commit_data *data = calldata;
  
  	data->completion_ops->completion(data);
  	pnfs_put_lseg(data->lseg);
  	nfs_put_client(data->ds_clp);
  	nfs_commitdata_release(data);
  }
  EXPORT_SYMBOL_GPL(pnfs_generic_commit_release);

  static struct pnfs_layout_segment *
  pnfs_free_bucket_lseg(struct pnfs_commit_bucket *bucket)
  {
  	if (list_empty(&bucket->committing) && list_empty(&bucket->written)) {
  		struct pnfs_layout_segment *freeme = bucket->lseg;
  		bucket->lseg = NULL;
  		return freeme;
  	}
  	return NULL;
  }

  /* The generic layer is about to remove the req from the commit list.
   * If this will make the bucket empty, it will need to put the lseg reference.

   * Note this must be called holding nfsi->commit_mutex

   */
  void
  pnfs_generic_clear_request_commit(struct nfs_page *req,
  				  struct nfs_commit_info *cinfo)
  {

  	struct pnfs_commit_bucket *bucket = NULL;

  
  	if (!test_and_clear_bit(PG_COMMIT_TO_DS, &req->wb_flags))
  		goto out;
  	cinfo->ds->nwritten--;

  	if (list_is_singular(&req->wb_list))

  		bucket = list_first_entry(&req->wb_list,

  					  struct pnfs_commit_bucket, written);

  out:
  	nfs_request_remove_commit_list(req, cinfo);

  	if (bucket)
  		pnfs_put_lseg(pnfs_free_bucket_lseg(bucket));

  }
  EXPORT_SYMBOL_GPL(pnfs_generic_clear_request_commit);

  struct pnfs_commit_array *
  pnfs_alloc_commit_array(size_t n, gfp_t gfp_flags)
  {
  	struct pnfs_commit_array *p;
  	struct pnfs_commit_bucket *b;
  
  	p = kmalloc(struct_size(p, buckets, n), gfp_flags);
  	if (!p)
  		return NULL;
  	p->nbuckets = n;
  	INIT_LIST_HEAD(&p->cinfo_list);
  	INIT_LIST_HEAD(&p->lseg_list);
  	p->lseg = NULL;
  	for (b = &p->buckets[0]; n != 0; b++, n--) {
  		INIT_LIST_HEAD(&b->written);
  		INIT_LIST_HEAD(&b->committing);

  		b->lseg = NULL;

  		b->direct_verf.committed = NFS_INVALID_STABLE_HOW;
  	}
  	return p;
  }
  EXPORT_SYMBOL_GPL(pnfs_alloc_commit_array);
  
  void
  pnfs_free_commit_array(struct pnfs_commit_array *p)
  {
  	kfree_rcu(p, rcu);
  }
  EXPORT_SYMBOL_GPL(pnfs_free_commit_array);

  static struct pnfs_commit_array *
  pnfs_find_commit_array_by_lseg(struct pnfs_ds_commit_info *fl_cinfo,
  		struct pnfs_layout_segment *lseg)
  {
  	struct pnfs_commit_array *array;
  
  	list_for_each_entry_rcu(array, &fl_cinfo->commits, cinfo_list) {
  		if (array->lseg == lseg)
  			return array;
  	}
  	return NULL;
  }
  
  struct pnfs_commit_array *
  pnfs_add_commit_array(struct pnfs_ds_commit_info *fl_cinfo,
  		struct pnfs_commit_array *new,
  		struct pnfs_layout_segment *lseg)
  {
  	struct pnfs_commit_array *array;
  
  	array = pnfs_find_commit_array_by_lseg(fl_cinfo, lseg);
  	if (array)
  		return array;
  	new->lseg = lseg;
  	refcount_set(&new->refcount, 1);
  	list_add_rcu(&new->cinfo_list, &fl_cinfo->commits);
  	list_add(&new->lseg_list, &lseg->pls_commits);
  	return new;
  }
  EXPORT_SYMBOL_GPL(pnfs_add_commit_array);

  static struct pnfs_commit_array *
  pnfs_lookup_commit_array(struct pnfs_ds_commit_info *fl_cinfo,
  		struct pnfs_layout_segment *lseg)
  {
  	struct pnfs_commit_array *array;
  
  	rcu_read_lock();
  	array = pnfs_find_commit_array_by_lseg(fl_cinfo, lseg);
  	if (!array) {
  		rcu_read_unlock();

  		fl_cinfo->ops->setup_ds_info(fl_cinfo, lseg);

  		rcu_read_lock();
  		array = pnfs_find_commit_array_by_lseg(fl_cinfo, lseg);
  	}
  	rcu_read_unlock();
  	return array;
  }

  static void
  pnfs_release_commit_array_locked(struct pnfs_commit_array *array)
  {
  	list_del_rcu(&array->cinfo_list);
  	list_del(&array->lseg_list);
  	pnfs_free_commit_array(array);
  }
  
  static void
  pnfs_put_commit_array_locked(struct pnfs_commit_array *array)
  {
  	if (refcount_dec_and_test(&array->refcount))
  		pnfs_release_commit_array_locked(array);
  }
  
  static void
  pnfs_put_commit_array(struct pnfs_commit_array *array, struct inode *inode)
  {
  	if (refcount_dec_and_lock(&array->refcount, &inode->i_lock)) {
  		pnfs_release_commit_array_locked(array);
  		spin_unlock(&inode->i_lock);
  	}
  }
  
  static struct pnfs_commit_array *
  pnfs_get_commit_array(struct pnfs_commit_array *array)
  {
  	if (refcount_inc_not_zero(&array->refcount))
  		return array;
  	return NULL;
  }
  
  static void
  pnfs_remove_and_free_commit_array(struct pnfs_commit_array *array)
  {
  	array->lseg = NULL;
  	list_del_init(&array->lseg_list);
  	pnfs_put_commit_array_locked(array);
  }
  
  void
  pnfs_generic_ds_cinfo_release_lseg(struct pnfs_ds_commit_info *fl_cinfo,
  		struct pnfs_layout_segment *lseg)
  {
  	struct pnfs_commit_array *array, *tmp;
  
  	list_for_each_entry_safe(array, tmp, &lseg->pls_commits, lseg_list)
  		pnfs_remove_and_free_commit_array(array);
  }
  EXPORT_SYMBOL_GPL(pnfs_generic_ds_cinfo_release_lseg);
  
  void
  pnfs_generic_ds_cinfo_destroy(struct pnfs_ds_commit_info *fl_cinfo)
  {
  	struct pnfs_commit_array *array, *tmp;
  
  	list_for_each_entry_safe(array, tmp, &fl_cinfo->commits, cinfo_list)
  		pnfs_remove_and_free_commit_array(array);
  }
  EXPORT_SYMBOL_GPL(pnfs_generic_ds_cinfo_destroy);

  /*
   * Locks the nfs_page requests for commit and moves them to
   * @bucket->committing.
   */

  static int

  pnfs_bucket_scan_ds_commit_list(struct pnfs_commit_bucket *bucket,
  				struct nfs_commit_info *cinfo,
  				int max)

  {
  	struct list_head *src = &bucket->written;
  	struct list_head *dst = &bucket->committing;
  	int ret;

  	lockdep_assert_held(&NFS_I(cinfo->inode)->commit_mutex);

  	ret = nfs_scan_commit_list(src, dst, cinfo, max);

  	if (ret) {
  		cinfo->ds->nwritten -= ret;
  		cinfo->ds->ncommitting += ret;

  	}
  	return ret;
  }

  static int pnfs_bucket_scan_array(struct nfs_commit_info *cinfo,
  				  struct pnfs_commit_bucket *buckets,
  				  unsigned int nbuckets,
  				  int max)
  {
  	unsigned int i;
  	int rv = 0, cnt;
  
  	for (i = 0; i < nbuckets && max != 0; i++) {
  		cnt = pnfs_bucket_scan_ds_commit_list(&buckets[i], cinfo, max);
  		rv += cnt;
  		max -= cnt;
  	}
  	return rv;
  }

  /* Move reqs from written to committing lists, returning count
   * of number moved.

   */

  int pnfs_generic_scan_commit_lists(struct nfs_commit_info *cinfo, int max)

  {

  	struct pnfs_ds_commit_info *fl_cinfo = cinfo->ds;
  	struct pnfs_commit_array *array;
  	int rv = 0, cnt;

  	rcu_read_lock();
  	list_for_each_entry_rcu(array, &fl_cinfo->commits, cinfo_list) {
  		if (!array->lseg || !pnfs_get_commit_array(array))
  			continue;
  		rcu_read_unlock();

  		cnt = pnfs_bucket_scan_array(cinfo, array->buckets,
  				array->nbuckets, max);

  		rcu_read_lock();
  		pnfs_put_commit_array(array, cinfo->inode);

  		rv += cnt;

  		max -= cnt;
  		if (!max)
  			break;

  	}

  	rcu_read_unlock();

  	return rv;
  }
  EXPORT_SYMBOL_GPL(pnfs_generic_scan_commit_lists);

  static unsigned int
  pnfs_bucket_recover_commit_reqs(struct list_head *dst,
  			        struct pnfs_commit_bucket *buckets,
  				unsigned int nbuckets,
  				struct nfs_commit_info *cinfo)

  {
  	struct pnfs_commit_bucket *b;
  	struct pnfs_layout_segment *freeme;

  	unsigned int nwritten, ret = 0;
  	unsigned int i;

  
  restart:

  	for (i = 0, b = buckets; i < nbuckets; i++, b++) {

  		nwritten = nfs_scan_commit_list(&b->written, dst, cinfo, 0);

  		if (!nwritten)
  			continue;

  		ret += nwritten;

  		freeme = pnfs_free_bucket_lseg(b);
  		if (freeme) {

  			pnfs_put_lseg(freeme);
  			goto restart;
  		}
  	}

  	return ret;
  }
  
  /* Pull everything off the committing lists and dump into @dst.  */
  void pnfs_generic_recover_commit_reqs(struct list_head *dst,
  				      struct nfs_commit_info *cinfo)
  {
  	struct pnfs_ds_commit_info *fl_cinfo = cinfo->ds;
  	struct pnfs_commit_array *array;
  	unsigned int nwritten;
  
  	lockdep_assert_held(&NFS_I(cinfo->inode)->commit_mutex);

  	rcu_read_lock();
  	list_for_each_entry_rcu(array, &fl_cinfo->commits, cinfo_list) {
  		if (!array->lseg || !pnfs_get_commit_array(array))
  			continue;
  		rcu_read_unlock();

  		nwritten = pnfs_bucket_recover_commit_reqs(dst,
  							   array->buckets,
  							   array->nbuckets,
  							   cinfo);

  		rcu_read_lock();
  		pnfs_put_commit_array(array, cinfo->inode);

  		fl_cinfo->nwritten -= nwritten;
  	}

  	rcu_read_unlock();

  }
  EXPORT_SYMBOL_GPL(pnfs_generic_recover_commit_reqs);

  static struct nfs_page *
  pnfs_bucket_search_commit_reqs(struct pnfs_commit_bucket *buckets,
  		unsigned int nbuckets, struct page *page)
  {
  	struct nfs_page *req;
  	struct pnfs_commit_bucket *b;
  	unsigned int i;
  
  	/* Linearly search the commit lists for each bucket until a matching
  	 * request is found */
  	for (i = 0, b = buckets; i < nbuckets; i++, b++) {
  		list_for_each_entry(req, &b->written, wb_list) {
  			if (req->wb_page == page)
  				return req->wb_head;
  		}
  		list_for_each_entry(req, &b->committing, wb_list) {
  			if (req->wb_page == page)
  				return req->wb_head;
  		}
  	}
  	return NULL;
  }
  
  /* pnfs_generic_search_commit_reqs - Search lists in @cinfo for the head reqest
   *				   for @page
   * @cinfo - commit info for current inode
   * @page - page to search for matching head request
   *
   * Returns a the head request if one is found, otherwise returns NULL.
   */
  struct nfs_page *
  pnfs_generic_search_commit_reqs(struct nfs_commit_info *cinfo, struct page *page)
  {
  	struct pnfs_ds_commit_info *fl_cinfo = cinfo->ds;
  	struct pnfs_commit_array *array;
  	struct nfs_page *req;

  	list_for_each_entry(array, &fl_cinfo->commits, cinfo_list) {
  		req = pnfs_bucket_search_commit_reqs(array->buckets,
  				array->nbuckets, page);
  		if (req)
  			return req;
  	}
  	return NULL;
  }
  EXPORT_SYMBOL_GPL(pnfs_generic_search_commit_reqs);

  static struct pnfs_layout_segment *
  pnfs_bucket_get_committing(struct list_head *head,
  			   struct pnfs_commit_bucket *bucket,
  			   struct nfs_commit_info *cinfo)

  {

  	struct pnfs_layout_segment *lseg;

  	struct list_head *pos;

  
  	list_for_each(pos, &bucket->committing)
  		cinfo->ds->ncommitting--;
  	list_splice_init(&bucket->committing, head);

  	lseg = pnfs_free_bucket_lseg(bucket);
  	if (!lseg)
  		lseg = pnfs_get_lseg(bucket->lseg);
  	return lseg;

  }
  
  static struct nfs_commit_data *
  pnfs_bucket_fetch_commitdata(struct pnfs_commit_bucket *bucket,
  			     struct nfs_commit_info *cinfo)
  {
  	struct nfs_commit_data *data = nfs_commitdata_alloc(false);
  
  	if (!data)
  		return NULL;
  	data->lseg = pnfs_bucket_get_committing(&data->pages, bucket, cinfo);
  	return data;
  }
  
  static void pnfs_generic_retry_commit(struct pnfs_commit_bucket *buckets,
  				      unsigned int nbuckets,
  				      struct nfs_commit_info *cinfo,
  				      unsigned int idx)
  {
  	struct pnfs_commit_bucket *bucket;
  	struct pnfs_layout_segment *freeme;

  	LIST_HEAD(pages);

  	for (bucket = buckets; idx < nbuckets; bucket++, idx++) {

  		if (list_empty(&bucket->committing))
  			continue;

  		mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
  		freeme = pnfs_bucket_get_committing(&pages, bucket, cinfo);

  		mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);

  		nfs_retry_commit(&pages, freeme, cinfo, idx);

  		pnfs_put_lseg(freeme);
  	}
  }
  
  static unsigned int

  pnfs_bucket_alloc_ds_commits(struct list_head *list,
  			     struct pnfs_commit_bucket *buckets,
  			     unsigned int nbuckets,
  			     struct nfs_commit_info *cinfo)

  {

  	struct pnfs_commit_bucket *bucket;
  	struct nfs_commit_data *data;

  	unsigned int i;

  	unsigned int nreq = 0;

  	for (i = 0, bucket = buckets; i < nbuckets; i++, bucket++) {

  		if (list_empty(&bucket->committing))
  			continue;

  		mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
  		if (!list_empty(&bucket->committing)) {
  			data = pnfs_bucket_fetch_commitdata(bucket, cinfo);
  			if (!data)
  				goto out_error;
  			data->ds_commit_index = i;
  			list_add_tail(&data->list, list);
  			atomic_inc(&cinfo->mds->rpcs_out);
  			nreq++;
  		}
  		mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);

  	}

  	return nreq;

  out_error:

  	mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);

  	/* Clean up on error */
  	pnfs_generic_retry_commit(buckets, nbuckets, cinfo, i);
  	return nreq;

  }

  static unsigned int
  pnfs_alloc_ds_commits_list(struct list_head *list,
  			   struct pnfs_ds_commit_info *fl_cinfo,
  			   struct nfs_commit_info *cinfo)
  {
  	struct pnfs_commit_array *array;
  	unsigned int ret = 0;

  	rcu_read_lock();
  	list_for_each_entry_rcu(array, &fl_cinfo->commits, cinfo_list) {
  		if (!array->lseg || !pnfs_get_commit_array(array))
  			continue;
  		rcu_read_unlock();

  		ret += pnfs_bucket_alloc_ds_commits(list, array->buckets,
  				array->nbuckets, cinfo);

  		rcu_read_lock();
  		pnfs_put_commit_array(array, cinfo->inode);
  	}

  	rcu_read_unlock();

  	return ret;
  }

  /* This follows nfs_commit_list pretty closely */
  int
  pnfs_generic_commit_pagelist(struct inode *inode, struct list_head *mds_pages,
  			     int how, struct nfs_commit_info *cinfo,
  			     int (*initiate_commit)(struct nfs_commit_data *data,
  						    int how))
  {

  	struct pnfs_ds_commit_info *fl_cinfo = cinfo->ds;

  	struct nfs_commit_data *data, *tmp;
  	LIST_HEAD(list);
  	unsigned int nreq = 0;
  
  	if (!list_empty(mds_pages)) {

  		data = nfs_commitdata_alloc(true);
  		data->ds_commit_index = -1;

  		list_splice_init(mds_pages, &data->pages);
  		list_add_tail(&data->list, &list);
  		atomic_inc(&cinfo->mds->rpcs_out);

  		nreq++;

  	}

  	nreq += pnfs_alloc_ds_commits_list(&list, fl_cinfo, cinfo);

  	if (nreq == 0)

  		goto out;

  	list_for_each_entry_safe(data, tmp, &list, list) {
  		list_del(&data->list);

  		if (data->ds_commit_index < 0) {

  			nfs_init_commit(data, NULL, NULL, cinfo);

  			nfs_initiate_commit(NFS_CLIENT(inode), data,

  					    NFS_PROTO(data->inode),

  					    data->mds_ops, how,
  					    RPC_TASK_CRED_NOREF);

  		} else {

  			nfs_init_commit(data, NULL, data->lseg, cinfo);

  			initiate_commit(data, how);
  		}
  	}
  out:

  	return PNFS_ATTEMPTED;
  }
  EXPORT_SYMBOL_GPL(pnfs_generic_commit_pagelist);

  
  /*
   * 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.
   */
  static DEFINE_SPINLOCK(nfs4_ds_cache_lock);
  static LIST_HEAD(nfs4_data_server_cache);
  
  /* Debug routines */
  static void
  print_ds(struct nfs4_pnfs_ds *ds)
  {
  	if (ds == NULL) {
  		printk(KERN_WARNING "%s NULL device
  ", __func__);
  		return;
  	}
  	printk(KERN_WARNING "        ds %s
  "
  		"        ref count %d
  "
  		"        client %p
  "
  		"        cl_exchange_flags %x
  ",
  		ds->ds_remotestr,

  		refcount_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_src_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;
  }

  /*
   * Checks if 'dsaddrs1' contains a subset of 'dsaddrs2'. If it does,
   * declare a match.
   */

  static bool
  _same_data_server_addrs_locked(const struct list_head *dsaddrs1,
  			       const struct list_head *dsaddrs2)
  {
  	struct nfs4_pnfs_ds_addr *da1, *da2;

  	struct sockaddr *sa1, *sa2;
  	bool match = false;
  
  	list_for_each_entry(da1, dsaddrs1, da_node) {
  		sa1 = (struct sockaddr *)&da1->da_addr;
  		match = false;
  		list_for_each_entry(da2, dsaddrs2, da_node) {
  			sa2 = (struct sockaddr *)&da2->da_addr;
  			match = same_sockaddr(sa1, sa2);
  			if (match)
  				break;
  		}
  		if (!match)
  			break;

  	}

  	return match;

  }
  
  /*
   * Lookup DS by addresses.  nfs4_ds_cache_lock is held
   */
  static struct nfs4_pnfs_ds *
  _data_server_lookup_locked(const struct list_head *dsaddrs)
  {
  	struct nfs4_pnfs_ds *ds;
  
  	list_for_each_entry(ds, &nfs4_data_server_cache, ds_node)
  		if (_same_data_server_addrs_locked(&ds->ds_addrs, dsaddrs))
  			return ds;
  	return NULL;
  }
  
  static void destroy_ds(struct nfs4_pnfs_ds *ds)
  {
  	struct nfs4_pnfs_ds_addr *da;
  
  	dprintk("--> %s
  ", __func__);
  	ifdebug(FACILITY)
  		print_ds(ds);
  
  	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_pnfs_ds_put(struct nfs4_pnfs_ds *ds)
  {

  	if (refcount_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);
  	}
  }
  EXPORT_SYMBOL_GPL(nfs4_pnfs_ds_put);
  
  /*
   * 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;
  }
  
  /*
   * Given a list of multipath struct nfs4_pnfs_ds_addr, add it to ds cache if
   * uncached and return cached struct nfs4_pnfs_ds.
   */
  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;

  		refcount_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 {
  		kfree(remotestr);
  		kfree(ds);

  		refcount_inc(&tmp_ds->ds_count);

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

  			refcount_read(&tmp_ds->ds_count));

  		ds = tmp_ds;
  	}
  	spin_unlock(&nfs4_ds_cache_lock);
  out:
  	return ds;
  }
  EXPORT_SYMBOL_GPL(nfs4_pnfs_ds_add);

  static void nfs4_wait_ds_connect(struct nfs4_pnfs_ds *ds)
  {
  	might_sleep();
  	wait_on_bit(&ds->ds_state, NFS4DS_CONNECTING,
  			TASK_KILLABLE);
  }
  
  static void nfs4_clear_ds_conn_bit(struct nfs4_pnfs_ds *ds)
  {
  	smp_mb__before_atomic();
  	clear_bit(NFS4DS_CONNECTING, &ds->ds_state);
  	smp_mb__after_atomic();
  	wake_up_bit(&ds->ds_state, NFS4DS_CONNECTING);
  }

  static struct nfs_client *(*get_v3_ds_connect)(

  			struct nfs_server *mds_srv,

  			const struct sockaddr *ds_addr,
  			int ds_addrlen,
  			int ds_proto,
  			unsigned int ds_timeo,

  			unsigned int ds_retrans);

  
  static bool load_v3_ds_connect(void)
  {
  	if (!get_v3_ds_connect) {
  		get_v3_ds_connect = symbol_request(nfs3_set_ds_client);
  		WARN_ON_ONCE(!get_v3_ds_connect);
  	}
  
  	return(get_v3_ds_connect != NULL);
  }

  void nfs4_pnfs_v3_ds_connect_unload(void)

  {
  	if (get_v3_ds_connect) {
  		symbol_put(nfs3_set_ds_client);
  		get_v3_ds_connect = NULL;
  	}
  }

  
  static int _nfs4_pnfs_v3_ds_connect(struct nfs_server *mds_srv,
  				 struct nfs4_pnfs_ds *ds,
  				 unsigned int timeo,

  				 unsigned int retrans)

  {
  	struct nfs_client *clp = ERR_PTR(-EIO);
  	struct nfs4_pnfs_ds_addr *da;
  	int status = 0;

  	dprintk("--> %s DS %s
  ", __func__, ds->ds_remotestr);

  
  	if (!load_v3_ds_connect())
  		goto out;
  
  	list_for_each_entry(da, &ds->ds_addrs, da_node) {
  		dprintk("%s: DS %s: trying address %s
  ",
  			__func__, ds->ds_remotestr, da->da_remotestr);

  		if (!IS_ERR(clp)) {
  			struct xprt_create xprt_args = {
  				.ident = XPRT_TRANSPORT_TCP,
  				.net = clp->cl_net,
  				.dstaddr = (struct sockaddr *)&da->da_addr,
  				.addrlen = da->da_addrlen,
  				.servername = clp->cl_hostname,
  			};
  			/* Add this address as an alias */
  			rpc_clnt_add_xprt(clp->cl_rpcclient, &xprt_args,
  					rpc_clnt_test_and_add_xprt, NULL);

  			continue;
  		}
  		clp = get_v3_ds_connect(mds_srv,
  				(struct sockaddr *)&da->da_addr,
  				da->da_addrlen, IPPROTO_TCP,
  				timeo, retrans);
  		if (IS_ERR(clp))
  			continue;
  		clp->cl_rpcclient->cl_softerr = 0;
  		clp->cl_rpcclient->cl_softrtry = 0;

  	}
  
  	if (IS_ERR(clp)) {
  		status = PTR_ERR(clp);
  		goto out;
  	}
  
  	smp_wmb();
  	ds->ds_clp = clp;
  	dprintk("%s [new] addr: %s
  ", __func__, ds->ds_remotestr);
  out:
  	return status;
  }
  
  static int _nfs4_pnfs_v4_ds_connect(struct nfs_server *mds_srv,

  				 struct nfs4_pnfs_ds *ds,
  				 unsigned int timeo,

  				 unsigned int retrans,

  				 u32 minor_version)

  {
  	struct nfs_client *clp = ERR_PTR(-EIO);
  	struct nfs4_pnfs_ds_addr *da;
  	int status = 0;

  	dprintk("--> %s DS %s
  ", __func__, ds->ds_remotestr);

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

  		if (!IS_ERR(clp) && clp->cl_mvops->session_trunk) {
  			struct xprt_create xprt_args = {
  				.ident = XPRT_TRANSPORT_TCP,
  				.net = clp->cl_net,
  				.dstaddr = (struct sockaddr *)&da->da_addr,
  				.addrlen = da->da_addrlen,
  				.servername = clp->cl_hostname,
  			};
  			struct nfs4_add_xprt_data xprtdata = {
  				.clp = clp,
  				.cred = nfs4_get_clid_cred(clp),
  			};
  			struct rpc_add_xprt_test rpcdata = {
  				.add_xprt_test = clp->cl_mvops->session_trunk,
  				.data = &xprtdata,
  			};
  
  			/**
  			* Test this address for session trunking and
  			* add as an alias
  			*/
  			rpc_clnt_add_xprt(clp->cl_rpcclient, &xprt_args,
  					  rpc_clnt_setup_test_and_add_xprt,
  					  &rpcdata);
  			if (xprtdata.cred)

  				put_cred(xprtdata.cred);

  		} else {
  			clp = nfs4_set_ds_client(mds_srv,
  						(struct sockaddr *)&da->da_addr,
  						da->da_addrlen, IPPROTO_TCP,

  						timeo, retrans, minor_version);

  			if (IS_ERR(clp))
  				continue;
  
  			status = nfs4_init_ds_session(clp,
  					mds_srv->nfs_client->cl_lease_time);
  			if (status) {
  				nfs_put_client(clp);
  				clp = ERR_PTR(-EIO);
  				continue;
  			}
  
  		}

  	}
  
  	if (IS_ERR(clp)) {
  		status = PTR_ERR(clp);
  		goto out;
  	}

  	smp_wmb();
  	ds->ds_clp = clp;
  	dprintk("%s [new] addr: %s
  ", __func__, ds->ds_remotestr);
  out:
  	return status;

  }
  
  /*
   * Create an rpc connection to the nfs4_pnfs_ds data server.
   * Currently only supports IPv4 and IPv6 addresses.

   * If connection fails, make devid unavailable and return a -errno.

   */

  int nfs4_pnfs_ds_connect(struct nfs_server *mds_srv, struct nfs4_pnfs_ds *ds,

  			  struct nfs4_deviceid_node *devid, unsigned int timeo,

  			  unsigned int retrans, u32 version, u32 minor_version)

  {

  	int err;

  again:
  	err = 0;
  	if (test_and_set_bit(NFS4DS_CONNECTING, &ds->ds_state) == 0) {

  		if (version == 3) {
  			err = _nfs4_pnfs_v3_ds_connect(mds_srv, ds, timeo,

  						       retrans);

  		} else if (version == 4) {
  			err = _nfs4_pnfs_v4_ds_connect(mds_srv, ds, timeo,

  						       retrans, minor_version);

  		} else {
  			dprintk("%s: unsupported DS version %d
  ", __func__,
  				version);
  			err = -EPROTONOSUPPORT;
  		}

  		nfs4_clear_ds_conn_bit(ds);
  	} else {
  		nfs4_wait_ds_connect(ds);

  
  		/* what was waited on didn't connect AND didn't mark unavail */
  		if (!ds->ds_clp && !nfs4_test_deviceid_unavailable(devid))
  			goto again;

  	}

  
  	/*
  	 * At this point the ds->ds_clp should be ready, but it might have
  	 * hit an error.
  	 */

  	if (!err) {
  		if (!ds->ds_clp || !nfs_client_init_is_complete(ds->ds_clp)) {
  			WARN_ON_ONCE(ds->ds_clp ||
  				!nfs4_test_deviceid_unavailable(devid));
  			return -EINVAL;
  		}
  		err = nfs_client_init_status(ds->ds_clp);

  	}

  	return err;

  }
  EXPORT_SYMBOL_GPL(nfs4_pnfs_ds_connect);

  /*
   * Currently only supports ipv4, ipv6 and one multi-path address.
   */
  struct nfs4_pnfs_ds_addr *
  nfs4_decode_mp_ds_addr(struct net *net, struct xdr_stream *xdr, 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(xdr, 4);
  	if (unlikely(!p))
  		goto out_err;
  	nlen = be32_to_cpup(p++);
  
  	p = xdr_inline_decode(xdr, 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(xdr, 4);
  	if (unlikely(!p))
  		goto out_free_netid;
  	rlen = be32_to_cpup(p);
  
  	p = xdr_inline_decode(xdr, 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(net, 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;
  }
  EXPORT_SYMBOL_GPL(nfs4_decode_mp_ds_addr);

  
  void
  pnfs_layout_mark_request_commit(struct nfs_page *req,
  				struct pnfs_layout_segment *lseg,
  				struct nfs_commit_info *cinfo,
  				u32 ds_commit_idx)
  {
  	struct list_head *list;

  	struct pnfs_commit_array *array;

  	struct pnfs_commit_bucket *bucket;

  	mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);

  	array = pnfs_lookup_commit_array(cinfo->ds, lseg);

  	if (!array || !pnfs_is_valid_lseg(lseg))

  		goto out_resched;

  	bucket = &array->buckets[ds_commit_idx];
  	list = &bucket->written;
  	/* Non-empty buckets hold a reference on the lseg.  That ref
  	 * is normally transferred to the COMMIT call and released
  	 * there.  It could also be released if the last req is pulled
  	 * off due to a rewrite, in which case it will be done in
  	 * pnfs_common_clear_request_commit
  	 */
  	if (!bucket->lseg)
  		bucket->lseg = pnfs_get_lseg(lseg);

  	set_bit(PG_COMMIT_TO_DS, &req->wb_flags);
  	cinfo->ds->nwritten++;

  	nfs_request_add_commit_list_locked(req, list, cinfo);

  	mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);

  	nfs_mark_page_unstable(req->wb_page, cinfo);

  	return;
  out_resched:
  	mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
  	cinfo->completion_ops->resched_write(cinfo, req);

  }
  EXPORT_SYMBOL_GPL(pnfs_layout_mark_request_commit);

  
  int
  pnfs_nfs_generic_sync(struct inode *inode, bool datasync)
  {

  	int ret;
  
  	if (!pnfs_layoutcommit_outstanding(inode))
  		return 0;
  	ret = nfs_commit_inode(inode, FLUSH_SYNC);
  	if (ret < 0)
  		return ret;

  	if (datasync)
  		return 0;
  	return pnfs_layoutcommit_inode(inode, true);
  }
  EXPORT_SYMBOL_GPL(pnfs_nfs_generic_sync);