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022cae3655
This patch prepares p9_fcall structure for zero copy. Added fields send the payload buffer information to the transport layer. In addition it adds a 'private' field for the transport layer to store mapped/pinned page information so that it can be freed/unpinned during req_done. This patch also creates trans_common.[ch] to house helper functions. It adds the following helper functions. p9_release_req_pages - Release pages after the transaction. p9_nr_pages - Return number of pages needed to accomodate the payload. payload_gup - Translates user buffer into kernel pages. Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
98 lines
2.8 KiB
C
98 lines
2.8 KiB
C
/*
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* Copyright IBM Corporation, 2010
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* Author Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of version 2.1 of the GNU Lesser General Public License
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*
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*/
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <net/9p/9p.h>
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#include <net/9p/client.h>
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#include <linux/scatterlist.h>
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#include "trans_common.h"
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/**
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* p9_release_req_pages - Release pages after the transaction.
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* @*private: PDU's private page of struct trans_rpage_info
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*/
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void
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p9_release_req_pages(struct trans_rpage_info *rpinfo)
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{
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int i = 0;
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while (rpinfo->rp_data[i] && rpinfo->rp_nr_pages--) {
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put_page(rpinfo->rp_data[i]);
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i++;
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}
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}
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EXPORT_SYMBOL(p9_release_req_pages);
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/**
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* p9_nr_pages - Return number of pages needed to accomodate the payload.
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*/
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int
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p9_nr_pages(struct p9_req_t *req)
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{
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int start_page, end_page;
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start_page = (unsigned long long)req->tc->pubuf >> PAGE_SHIFT;
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end_page = ((unsigned long long)req->tc->pubuf + req->tc->pbuf_size +
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PAGE_SIZE - 1) >> PAGE_SHIFT;
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return end_page - start_page;
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}
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EXPORT_SYMBOL(p9_nr_pages);
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/**
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* payload_gup - Translates user buffer into kernel pages and
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* pins them either for read/write through get_user_pages_fast().
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* @req: Request to be sent to server.
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* @pdata_off: data offset into the first page after translation (gup).
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* @pdata_len: Total length of the IO. gup may not return requested # of pages.
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* @nr_pages: number of pages to accomodate the payload
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* @rw: Indicates if the pages are for read or write.
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*/
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int
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p9_payload_gup(struct p9_req_t *req, size_t *pdata_off, int *pdata_len,
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int nr_pages, u8 rw)
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{
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uint32_t first_page_bytes = 0;
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uint32_t pdata_mapped_pages;
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struct trans_rpage_info *rpinfo;
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*pdata_off = (size_t)req->tc->pubuf & (PAGE_SIZE-1);
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if (*pdata_off)
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first_page_bytes = min((PAGE_SIZE - *pdata_off),
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req->tc->pbuf_size);
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rpinfo = req->tc->private;
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pdata_mapped_pages = get_user_pages_fast((unsigned long)req->tc->pubuf,
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nr_pages, rw, &rpinfo->rp_data[0]);
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if (pdata_mapped_pages < 0) {
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printk(KERN_ERR "get_user_pages_fast failed:%d udata:%p"
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"nr_pages:%d\n", pdata_mapped_pages,
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req->tc->pubuf, nr_pages);
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pdata_mapped_pages = 0;
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return -EIO;
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}
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rpinfo->rp_nr_pages = pdata_mapped_pages;
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if (*pdata_off) {
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*pdata_len = first_page_bytes;
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*pdata_len += min((req->tc->pbuf_size - *pdata_len),
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((size_t)pdata_mapped_pages - 1) << PAGE_SHIFT);
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} else {
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*pdata_len = min(req->tc->pbuf_size,
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(size_t)pdata_mapped_pages << PAGE_SHIFT);
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}
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return 0;
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}
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EXPORT_SYMBOL(p9_payload_gup);
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