net/9p/trans_common.c

   1 /*
   2  * Copyright IBM Corporation, 2010
   3  * Author Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of version 2.1 of the GNU Lesser General Public License
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  12  *
  13  */
  14
  15 #include <linux/slab.h>
  16 #include <linux/module.h>
  17 #include <net/9p/9p.h>
  18 #include <net/9p/client.h>
  19 #include <linux/scatterlist.h>
  20 #include "trans_common.h"
  21
  22 /**
  23  *  p9_release_req_pages - Release pages after the transaction.
  24  *  @*private: PDU's private page of struct trans_rpage_info
  25  */
  26 void
  27 p9_release_req_pages(struct trans_rpage_info *rpinfo)
  28 {
  29         int i = 0;
  30
  31         while (rpinfo->rp_data[i] && rpinfo->rp_nr_pages--) {
  32                 put_page(rpinfo->rp_data[i]);
  33                 i++;
  34         }
  35 }
  36 EXPORT_SYMBOL(p9_release_req_pages);
  37
  38 /**
  39  * p9_nr_pages - Return number of pages needed to accommodate the payload.
  40  */
  41 int
  42 p9_nr_pages(struct p9_req_t *req)
  43 {
  44         unsigned long start_page, end_page;
  45         start_page =  (unsigned long)req->tc->pubuf >> PAGE_SHIFT;
  46         end_page = ((unsigned long)req->tc->pubuf + req->tc->pbuf_size +
  47                         PAGE_SIZE - 1) >> PAGE_SHIFT;
  48         return end_page - start_page;
  49 }
  50 EXPORT_SYMBOL(p9_nr_pages);
  51
  52 /**
  53  * payload_gup - Translates user buffer into kernel pages and
  54  * pins them either for read/write through get_user_pages_fast().
  55  * @req: Request to be sent to server.
  56  * @pdata_off: data offset into the first page after translation (gup).
  57  * @pdata_len: Total length of the IO. gup may not return requested # of pages.
  58  * @nr_pages: number of pages to accommodate the payload
  59  * @rw: Indicates if the pages are for read or write.
  60  */
  61 int
  62 p9_payload_gup(struct p9_req_t *req, size_t *pdata_off, int *pdata_len,
  63                 int nr_pages, u8 rw)
  64 {
  65         uint32_t first_page_bytes = 0;
  66         int32_t pdata_mapped_pages;
  67         struct trans_rpage_info  *rpinfo;
  68
  69         *pdata_off = (__force size_t)req->tc->pubuf & (PAGE_SIZE-1);
  70
  71         if (*pdata_off)
  72                 first_page_bytes = min(((size_t)PAGE_SIZE - *pdata_off),
  73                                        req->tc->pbuf_size);
  74
  75         rpinfo = req->tc->private;
  76         pdata_mapped_pages = get_user_pages_fast((unsigned long)req->tc->pubuf,
  77                         nr_pages, rw, &rpinfo->rp_data[0]);
  78         if (pdata_mapped_pages <= 0)
  79                 return pdata_mapped_pages;
  80
  81         rpinfo->rp_nr_pages = pdata_mapped_pages;
  82         if (*pdata_off) {
  83                 *pdata_len = first_page_bytes;
  84                 *pdata_len += min((req->tc->pbuf_size - *pdata_len),
  85                                 ((size_t)pdata_mapped_pages - 1) << PAGE_SHIFT);
  86         } else {
  87                 *pdata_len = min(req->tc->pbuf_size,
  88                                 (size_t)pdata_mapped_pages << PAGE_SHIFT);
  89         }
  90         return 0;
  91 }
  92 EXPORT_SYMBOL(p9_payload_gup);