trans_common.c
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/*
* 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);