This patch avoids copy_from_user by employing get_user_pages_fast() on the
udata buffer. This will eliminate an additonal copy of user buffer into
kernel buffer befre placing on the virtio ring.
Signed-off-by: Venkateswararao Jujjuri <jvrao@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Badari Pulavarty <pbadari@xxxxxxxxxx>
---
net/9p/client.c | 32 ++++++++++++++++++++-
net/9p/protocol.c | 83 +++++++++++++++++++++++++++++++++++++++++++++++------
2 files changed, 105 insertions(+), 10 deletions(-)
diff --git a/net/9p/client.c b/net/9p/client.c
index 5487896..7ce58fb 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -36,6 +36,7 @@
#include <linux/parser.h>
#include <net/9p/client.h>
#include <net/9p/transport.h>
+#include <linux/mm.h>
#include "protocol.h"
/*
@@ -521,6 +522,25 @@ static int p9_client_flush(struct p9_client *c, struct p9_req_t *oldreq)
}
/**
+ * p9_release_req_pages - Release pages after the transaction.
+ * @req - Request buffer.
+ *
+ */
+static void
+p9_release_req_pages(struct p9_req_t *req)
+{
+ int i = 0;
+ while (req->tc->pdata[i] && req->tc->pdata_mapped_pages--) {
+ put_page(req->tc->pdata[i]);
+ req->tc->pdata[i] = NULL;
+ i++;
+ }
+ req->tc->pdata_write_len = 0;
+ req->tc->pdata_read_len = 0;
+}
+
+
+/**
* p9_client_rpc - issue a request and wait for a response
* @c: client session
* @type: type of request
@@ -575,6 +595,8 @@ p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...)
err = c->trans_mod->request(c, req);
if (err < 0) {
c->status = Disconnected;
+ if (req->tc->pdata_write_len || req->tc->pdata_read_len)
+ p9_release_req_pages(req);
goto reterr;
}
@@ -583,6 +605,8 @@ p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...)
req->status >= REQ_STATUS_RCVD);
P9_DPRINTK(P9_DEBUG_MUX, "wait %p tag: %d returned %d\n",
req->wq, tag, err);
+ if (req->tc->pdata_write_len || req->tc->pdata_read_len)
+ p9_release_req_pages(req);
if (req->status == REQ_STATUS_ERROR) {
P9_DPRINTK(P9_DEBUG_ERROR, "req_status error %d\n", req->t_err);
@@ -1331,9 +1355,15 @@ p9_client_write(struct p9_fid *fid, char *data, const char __user *udata,
if (data)
req = p9_client_rpc(clnt, P9_TWRITE, "dqD", fid->fid, offset,
rsize, data);
- else
+ else {
+ if (clnt->trans_mod->capability &&
+ clnt->trans_mod->capability(P9_CAP_GET_MAX_SG_PAGES)) {
+
+ rsize = count;
+ }
req = p9_client_rpc(clnt, P9_TWRITE, "dqU", fid->fid, offset,
rsize, udata);
+ }
if (IS_ERR(req)) {
err = PTR_ERR(req);
goto error;
diff --git a/net/9p/protocol.c b/net/9p/protocol.c
index ca63aff..97f313d 100644
--- a/net/9p/protocol.c
+++ b/net/9p/protocol.c
@@ -31,9 +31,12 @@
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/types.h>
+#include <linux/parser.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include "protocol.h"
+#include <net/9p/transport.h>
+#include <linux/pagemap.h>
#ifndef MIN
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
@@ -110,6 +113,51 @@ static size_t pdu_read(struct p9_fcall *pdu, void *data, size_t size)
return size - len;
}
+static int
+pdu_fill_pages(struct p9_fcall *pdu, const char __user *udata, size_t size,
+ int rw, int max_sg_pages)
+{
+ int nr_pages;
+ uint32_t first_page_bytes = 0;
+ int pdata_len;
+
+ nr_pages = size >> PAGE_SHIFT;
+ pdu->pdata_off = (size_t)udata & (PAGE_SIZE-1);
+ if (pdu->pdata_off)
+ first_page_bytes = PAGE_SIZE - pdu->pdata_off;
+ if (size - (first_page_bytes + (nr_pages << PAGE_SHIFT))) {
+ /* trailing partial page */
+ nr_pages++;
+ }
+ if (first_page_bytes) {
+ /* leading partial page */
+ nr_pages++;
+ }
+ nr_pages = min(max_sg_pages, nr_pages);
+ pdu->pdata = (struct page **)(pdu->sdata + pdu->size);
+ pdu->pdata_write_len = 0;
+ pdu->pdata_read_len = 0;
+ pdu->pdata_mapped_pages = get_user_pages_fast((unsigned long)udata,
+ nr_pages, rw, pdu->pdata);
+ if (pdu->pdata_mapped_pages < 0) {
+ printk(KERN_WARNING "get_user_pages_fast failed:%d udata:%p"
+ "nr_pages:%d\n", pdu->pdata_mapped_pages,
+ udata, nr_pages);
+ pdu->pdata_mapped_pages = 0;
+ return -1;
+ }
+ if (pdu->pdata_off) {
+ pdata_len = first_page_bytes;
+ pdata_len += min((size - pdata_len),
+ ((size_t)pdu->pdata_mapped_pages - 1) <<
+ PAGE_SHIFT);
+ } else {
+ pdata_len = min(size, (size_t)pdu->pdata_mapped_pages <<
+ PAGE_SHIFT);
+ }
+ return pdata_len;
+}
+
static size_t pdu_write(struct p9_fcall *pdu, const void *data, size_t size)
{
size_t len = MIN(pdu->capacity - pdu->size, size);
@@ -119,15 +167,31 @@ static size_t pdu_write(struct p9_fcall *pdu, const void *data, size_t size)
}
static size_t
-pdu_write_u(struct p9_fcall *pdu, const char __user *udata, size_t size)
+pdu_write_u(struct p9_fcall *pdu, struct p9_client *c, const char __user *udata,
+ size_t size)
{
- size_t len = MIN(pdu->capacity - pdu->size, size);
- int err = copy_from_user(&pdu->sdata[pdu->size], udata, len);
- if (err)
- printk(KERN_WARNING "pdu_write_u returning: %d\n", err);
+ size_t len;
+ int err;
+ int max_req_sg_pages = 0;
- pdu->size += len;
- return size - len;
+ if (c->trans_mod->capability &&
+ (udata && !segment_eq(get_fs(), KERNEL_DS))) {
+ max_req_sg_pages =
+ c->trans_mod->capability(P9_CAP_GET_MAX_SG_PAGES);
+ }
+ if (max_req_sg_pages) {
+ len = pdu_fill_pages(pdu, udata, size, 0, max_req_sg_pages);
+ if (len < 0)
+ return len;
+ pdu->pdata_write_len = len;
+ } else {
+ len = MIN(pdu->capacity - pdu->size, size);
+ err = copy_from_user(&pdu->sdata[pdu->size], udata, len);
+ if (err)
+ printk(KERN_WARNING "pdu_write_u returning: %d\n", err);
+ pdu->size += len;
+ }
+ return len;
}
/*
@@ -467,7 +531,8 @@ p9pdu_vwritef(struct p9_fcall *pdu, struct p9_client *c, const char *fmt,
const char __user *udata =
va_arg(ap, const void __user *);
errcode = p9pdu_writef(pdu, c, "d", count);
- if (!errcode && pdu_write_u(pdu, udata, count))
+ if (!errcode &&
+ pdu_write_u(pdu, c, udata, count) < 0)
errcode = -EFAULT;
}
break;
--
1.6.5.2
--
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