[net/9p] Add gup/zero_copy support to VirtIO transport layer.
Modify p9_virtio_request() and req_done() functions to support
additional payload sent down to the transport layer through
tc->pubuf and tc->pkbuf.
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index c8f3f72..4b236de 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -45,6 +45,7 @@
#include <linux/scatterlist.h>
#include <linux/virtio.h>
#include <linux/virtio_9p.h>
+#include "trans_common.h"
#define VIRTQUEUE_NUM 128
@@ -155,6 +156,14 @@
rc->tag);
req = p9_tag_lookup(chan->client, rc->tag);
req->status = REQ_STATUS_RCVD;
+ if (req->tc->private) {
+ struct trans_rpage_info *rp = req->tc->private;
+ /*Release pages */
+ p9_release_req_pages(rp);
+ if (rp->rp_alloc)
+ kfree(rp);
+ req->tc->private = NULL;
+ }
p9_client_cb(chan->client, req);
} else {
spin_unlock_irqrestore(&chan->lock, flags);
@@ -203,6 +212,38 @@
}
/**
+ * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer,
+ * this takes a list of pages.
+ * @sg: scatter/gather list to pack into
+ * @start: which segment of the sg_list to start at
+ * @pdata_off: Offset into the first page
+ * @**pdata: a list of pages to add into sg.
+ * @count: amount of data to pack into the scatter/gather list
+ */
+static int
+pack_sg_list_p(struct scatterlist *sg, int start, int limit, size_t pdata_off,
+ struct page **pdata, int count)
+{
+ int s;
+ int i = 0;
+ int index = start;
+
+ if (pdata_off) {
+ s = min((int)(PAGE_SIZE - pdata_off), count);
+ sg_set_page(&sg[index++], pdata[i++], s, pdata_off);
+ count -= s;
+ }
+
+ while (count) {
+ BUG_ON(index > limit);
+ s = min((int)PAGE_SIZE, count);
+ sg_set_page(&sg[index++], pdata[i++], s, 0);
+ count -= s;
+ }
+ return index-start;
+}
+
+/**
* p9_virtio_request - issue a request
* @client: client instance issuing the request
* @req: request to be issued
@@ -212,22 +253,97 @@
static int
p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
{
- int in, out;
+ int in, out, inp, outp;
struct virtio_chan *chan = client->trans;
char *rdata = (char *)req->rc+sizeof(struct p9_fcall);
unsigned long flags;
- int err;
+ size_t pdata_off = 0;
+ struct trans_rpage_info *rpinfo = NULL;
+ int err, pdata_len = 0;
P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n");
req_retry:
req->status = REQ_STATUS_SENT;
+ if (req->tc->pbuf_size && (req->tc->pubuf && P9_IS_USER_CONTEXT)) {
+ int nr_pages = p9_nr_pages(req);
+ int rpinfo_size = sizeof(struct trans_rpage_info) +
+ sizeof(struct page *) * nr_pages;
+
+ if (rpinfo_size <= (req->tc->capacity - req->tc->size)) {
+ /* We can use sdata */
+ req->tc->private = req->tc->sdata + req->tc->size;
+ rpinfo = (struct trans_rpage_info *)req->tc->private;
+ rpinfo->rp_alloc = 0;
+ } else {
+ req->tc->private = kmalloc(rpinfo_size, GFP_NOFS);
+ if (!req->tc->private) {
+ P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: "
+ "private kmalloc returned NULL");
+ return -ENOMEM;
+ }
+ rpinfo = (struct trans_rpage_info *)req->tc->private;
+ rpinfo->rp_alloc = 1;
+ }
+
+ err = p9_payload_gup(req, &pdata_off, &pdata_len, nr_pages,
+ req->tc->id == P9_TREAD ? 1 : 0);
+ if (err < 0) {
+ if (rpinfo->rp_alloc)
+ kfree(rpinfo);
+ return err;
+ }
+ }
+
spin_lock_irqsave(&chan->lock, flags);
+
+ /* Handle out VirtIO ring buffers */
out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, req->tc->sdata,
- req->tc->size);
- in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM-out, rdata,
- client->msize);
+ req->tc->size);
+
+ if (req->tc->pbuf_size && (req->tc->id == P9_TWRITE)) {
+ /* We have additional write payload buffer to take care */
+ if (req->tc->pubuf && P9_IS_USER_CONTEXT) {
+ outp = pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM,
+ pdata_off, rpinfo->rp_data, pdata_len);
+ } else {
+ char *pbuf = req->tc->pubuf ? req->tc->pubuf :
+ req->tc->pkbuf;
+ outp = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, pbuf,
+ req->tc->pbuf_size);
+ }
+ out += outp;
+ }
+
+ /* Handle in VirtIO ring buffers */
+ if (req->tc->pbuf_size &&
+ ((req->tc->id == P9_TREAD) || (req->tc->id == P9_TREADDIR))) {
+ /*
+ * Take care of additional Read payload.
+ * 11 is the read/write header = PDU Header(7) + IO Size (4).
+ * Arrange in such a way that server places header in the
+ * alloced memory and payload onto the user buffer.
+ */
+ inp = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, rdata, 11);
+ /*
+ * Running executables in the filesystem may result in
+ * a read request with kernel buffer as opposed to user buffer.
+ */
+ if (req->tc->pubuf && P9_IS_USER_CONTEXT) {
+ in = pack_sg_list_p(chan->sg, out+inp, VIRTQUEUE_NUM,
+ pdata_off, rpinfo->rp_data, pdata_len);
+ } else {
+ char *pbuf = req->tc->pubuf ? req->tc->pubuf :
+ req->tc->pkbuf;
+ in = pack_sg_list(chan->sg, out+inp, VIRTQUEUE_NUM,
+ pbuf, req->tc->pbuf_size);
+ }
+ in += inp;
+ } else {
+ in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, rdata,
+ client->msize);
+ }
err = virtqueue_add_buf(chan->vq, chan->sg, out, in, req->tc);
if (err < 0) {
@@ -246,6 +362,8 @@
P9_DPRINTK(P9_DEBUG_TRANS,
"9p debug: "
"virtio rpc add_buf returned failure");
+ if (rpinfo && rpinfo->rp_alloc)
+ kfree(rpinfo);
return -EIO;
}
}
