[net/9p] Add gup/zero_copy support to VirtIO transport layer. (4038866d) · Commits · e / devices / android_kernel_xiaomi_markw

net/9p/trans_common.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -12,6 +12,9 @@
		*
		*/

		/* TRUE if it is user context */
		#define P9_IS_USER_CONTEXT (!segment_eq(get_fs(), KERNEL_DS))

		/**
		* 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.

net/9p/trans_virtio.c

+123 −5

Original line number	Diff line number	Diff line
		@@ -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 @@ static void req_done(struct virtqueue *vq)
		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);
		@@ -202,6 +211,38 @@ static int p9_virtio_cancel(struct p9_client client, struct p9_req_t req)
		return 1;
		}

		/**
		* 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
		@@ -212,22 +253,97 @@ static int p9_virtio_cancel(struct p9_client client, struct p9_req_t req)
		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,

		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 @@ req_retry:
		P9_DPRINTK(P9_DEBUG_TRANS,
		"9p debug: "
		"virtio rpc add_buf returned failure");
		if (rpinfo && rpinfo->rp_alloc)
		kfree(rpinfo);
		return -EIO;
		}
		}