Commit 022cae36 authored by Venkateswararao Jujjuri (JV)'s avatar Venkateswararao Jujjuri (JV) Committed by Eric Van Hensbergen
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[net/9p] Preparation and helper functions for zero copy



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: default avatarVenkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: default avatarEric Van Hensbergen <ericvh@gmail.com>
parent 6752a1eb
......@@ -689,6 +689,10 @@ struct p9_rwstat {
* @tag: transaction id of the request
* @offset: used by marshalling routines to track currentposition in buffer
* @capacity: used by marshalling routines to track total capacity
* @pubuf: Payload user buffer given by the caller
* @pubuf: Payload kernel buffer given by the caller
* @pbuf_size: pubuf/pkbuf(only one will be !NULL) size to be read/write.
* @private: For transport layer's use.
* @sdata: payload
*
* &p9_fcall represents the structure for all 9P RPC
......@@ -705,6 +709,10 @@ struct p9_fcall {
size_t offset;
size_t capacity;
char __user *pubuf;
char *pkbuf;
size_t pbuf_size;
void *private;
uint8_t *sdata;
};
......
......@@ -9,6 +9,7 @@ obj-$(CONFIG_NET_9P_RDMA) += 9pnet_rdma.o
util.o \
protocol.o \
trans_fd.o \
trans_common.o \
9pnet_virtio-objs := \
trans_virtio.o \
......
......@@ -606,6 +606,10 @@ void p9pdu_reset(struct p9_fcall *pdu)
{
pdu->offset = 0;
pdu->size = 0;
pdu->private = NULL;
pdu->pubuf = NULL;
pdu->pkbuf = NULL;
pdu->pbuf_size = 0;
}
int p9dirent_read(char *buf, int len, struct p9_dirent *dirent,
......
/*
* 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.
* @*private: PDU's private page of struct trans_rpage_info
*/
void
p9_release_req_pages(struct trans_rpage_info *rpinfo)
{
int i = 0;
while (rpinfo->rp_data[i] && rpinfo->rp_nr_pages--) {
put_page(rpinfo->rp_data[i]);
i++;
}
}
EXPORT_SYMBOL(p9_release_req_pages);
/**
* p9_nr_pages - Return number of pages needed to accomodate the payload.
*/
int
p9_nr_pages(struct p9_req_t *req)
{
int start_page, end_page;
start_page = (unsigned long long)req->tc->pubuf >> PAGE_SHIFT;
end_page = ((unsigned long long)req->tc->pubuf + req->tc->pbuf_size +
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 accomodate the payload
* @rw: Indicates if the pages are for read or write.
*/
int
p9_payload_gup(struct p9_req_t *req, size_t *pdata_off, int *pdata_len,
int nr_pages, u8 rw)
{
uint32_t first_page_bytes = 0;
uint32_t pdata_mapped_pages;
struct trans_rpage_info *rpinfo;
*pdata_off = (size_t)req->tc->pubuf & (PAGE_SIZE-1);
if (*pdata_off)
first_page_bytes = min((PAGE_SIZE - *pdata_off),
req->tc->pbuf_size);
rpinfo = req->tc->private;
pdata_mapped_pages = get_user_pages_fast((unsigned long)req->tc->pubuf,
nr_pages, rw, &rpinfo->rp_data[0]);
if (pdata_mapped_pages < 0) {
printk(KERN_ERR "get_user_pages_fast failed:%d udata:%p"
"nr_pages:%d\n", pdata_mapped_pages,
req->tc->pubuf, nr_pages);
pdata_mapped_pages = 0;
return -EIO;
}
rpinfo->rp_nr_pages = pdata_mapped_pages;
if (*pdata_off) {
*pdata_len = first_page_bytes;
*pdata_len += min((req->tc->pbuf_size - *pdata_len),
((size_t)pdata_mapped_pages - 1) << PAGE_SHIFT);
} else {
*pdata_len = min(req->tc->pbuf_size,
(size_t)pdata_mapped_pages << PAGE_SHIFT);
}
return 0;
}
EXPORT_SYMBOL(p9_payload_gup);
/*
* 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.
*
*/
/**
* struct trans_rpage_info - To store mapped page information in PDU.
* @rp_alloc:Set if this structure is allocd, not a reuse unused space in pdu.
* @rp_nr_pages: Number of mapped pages
* @rp_data: Array of page pointers
*/
struct trans_rpage_info {
u8 rp_alloc;
int rp_nr_pages;
struct page *rp_data[0];
};
void p9_release_req_pages(struct trans_rpage_info *);
int p9_payload_gup(struct p9_req_t *, size_t *, int *, int, u8);
int p9_nr_pages(struct p9_req_t *);
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