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 */ 25 void p9_release_pages(struct page **pages, int nr_pages) 26 { 27 int i = 0; 28 while (pages[i] && nr_pages--) { 29 put_page(pages[i]); 30 i++; 31 } 32 } 33 EXPORT_SYMBOL(p9_release_pages); 34 35 /** 36 * p9_nr_pages - Return number of pages needed to accommodate the payload. 37 */ 38 int p9_nr_pages(char *data, int len) 39 { 40 unsigned long start_page, end_page; 41 start_page = (unsigned long)data >> PAGE_SHIFT; 42 end_page = ((unsigned long)data + len + PAGE_SIZE - 1) >> PAGE_SHIFT; 43 return end_page - start_page; 44 } 45 EXPORT_SYMBOL(p9_nr_pages); 46 47 /** 48 * payload_gup - Translates user buffer into kernel pages and 49 * pins them either for read/write through get_user_pages_fast(). 50 * @req: Request to be sent to server. 51 * @pdata_off: data offset into the first page after translation (gup). 52 * @pdata_len: Total length of the IO. gup may not return requested # of pages. 53 * @nr_pages: number of pages to accommodate the payload 54 * @rw: Indicates if the pages are for read or write. 55 */ 56 57 int p9_payload_gup(char *data, int *nr_pages, struct page **pages, int write) 58 { 59 int nr_mapped_pages; 60 61 nr_mapped_pages = get_user_pages_fast((unsigned long)data, 62 *nr_pages, write, pages); 63 if (nr_mapped_pages <= 0) 64 return nr_mapped_pages; 65 66 *nr_pages = nr_mapped_pages; 67 return 0; 68 } 69 EXPORT_SYMBOL(p9_payload_gup); 70