/*
   * Copyright IBM Corporation, 2010
   * Author Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of version 2.1 of the GNU Lesser General Public License
   * as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it would be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   *
   */
  
  #include <linux/slab.h>
  #include <linux/module.h>
  #include <net/9p/9p.h>
  #include <net/9p/client.h>
  #include <linux/scatterlist.h>
  #include "trans_common.h"
  
  /**
   *  p9_release_req_pages - Release pages after the transaction.

   */

  void p9_release_pages(struct page **pages, int nr_pages)

  {

  	int i;
  
  	for (i = 0; i < nr_pages; i++)
  		if (pages[i])
  			put_page(pages[i]);

  }

  EXPORT_SYMBOL(p9_release_pages);

  
  /**

   * p9_nr_pages - Return number of pages needed to accommodate the payload.

   */

  int p9_nr_pages(char *data, int len)

  {

  	unsigned long start_page, end_page;

  	start_page =  (unsigned long)data >> PAGE_SHIFT;
  	end_page = ((unsigned long)data + len + PAGE_SIZE - 1) >> PAGE_SHIFT;

  	return end_page - start_page;
  }
  EXPORT_SYMBOL(p9_nr_pages);
  
  /**
   * payload_gup - Translates user buffer into kernel pages and
   * pins them either for read/write through get_user_pages_fast().
   * @req: Request to be sent to server.
   * @pdata_off: data offset into the first page after translation (gup).
   * @pdata_len: Total length of the IO. gup may not return requested # of pages.

   * @nr_pages: number of pages to accommodate the payload

   * @rw: Indicates if the pages are for read or write.
   */

  int p9_payload_gup(char *data, int *nr_pages, struct page **pages, int write)
  {
  	int nr_mapped_pages;

  	nr_mapped_pages = get_user_pages_fast((unsigned long)data,
  					      *nr_pages, write, pages);
  	if (nr_mapped_pages <= 0)
  		return nr_mapped_pages;

  	*nr_pages = nr_mapped_pages;

  	return 0;
  }
  EXPORT_SYMBOL(p9_payload_gup);