mirror of https://gitee.com/openkylin/linux.git
623 lines
16 KiB
C
623 lines
16 KiB
C
/*
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* The Virtio 9p transport driver
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*
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* This is a block based transport driver based on the lguest block driver
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* code.
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*
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* Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation
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*
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* Based on virtio console driver
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* Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2
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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 will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to:
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* Free Software Foundation
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* 51 Franklin Street, Fifth Floor
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* Boston, MA 02111-1301 USA
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*
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*/
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#include <linux/in.h>
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#include <linux/module.h>
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#include <linux/net.h>
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#include <linux/ipv6.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/un.h>
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#include <linux/uaccess.h>
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#include <linux/inet.h>
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#include <linux/idr.h>
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#include <linux/file.h>
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#include <linux/slab.h>
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#include <net/9p/9p.h>
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#include <linux/parser.h>
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#include <net/9p/client.h>
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#include <net/9p/transport.h>
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#include <linux/scatterlist.h>
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#include <linux/swap.h>
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#include <linux/virtio.h>
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#include <linux/virtio_9p.h>
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#include "trans_common.h"
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#define VIRTQUEUE_NUM 128
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/* a single mutex to manage channel initialization and attachment */
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static DEFINE_MUTEX(virtio_9p_lock);
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static DECLARE_WAIT_QUEUE_HEAD(vp_wq);
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static atomic_t vp_pinned = ATOMIC_INIT(0);
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/**
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* struct virtio_chan - per-instance transport information
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* @initialized: whether the channel is initialized
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* @inuse: whether the channel is in use
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* @lock: protects multiple elements within this structure
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* @client: client instance
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* @vdev: virtio dev associated with this channel
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* @vq: virtio queue associated with this channel
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* @sg: scatter gather list which is used to pack a request (protected?)
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*
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* We keep all per-channel information in a structure.
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* This structure is allocated within the devices dev->mem space.
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* A pointer to the structure will get put in the transport private.
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*
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*/
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struct virtio_chan {
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bool inuse;
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spinlock_t lock;
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struct p9_client *client;
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struct virtio_device *vdev;
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struct virtqueue *vq;
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int ring_bufs_avail;
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wait_queue_head_t *vc_wq;
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/* This is global limit. Since we don't have a global structure,
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* will be placing it in each channel.
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*/
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int p9_max_pages;
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/* Scatterlist: can be too big for stack. */
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struct scatterlist sg[VIRTQUEUE_NUM];
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int tag_len;
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/*
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* tag name to identify a mount Non-null terminated
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*/
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char *tag;
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struct list_head chan_list;
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};
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static struct list_head virtio_chan_list;
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/* How many bytes left in this page. */
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static unsigned int rest_of_page(void *data)
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{
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return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE);
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}
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/**
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* p9_virtio_close - reclaim resources of a channel
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* @client: client instance
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*
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* This reclaims a channel by freeing its resources and
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* reseting its inuse flag.
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*
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*/
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static void p9_virtio_close(struct p9_client *client)
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{
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struct virtio_chan *chan = client->trans;
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mutex_lock(&virtio_9p_lock);
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if (chan)
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chan->inuse = false;
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mutex_unlock(&virtio_9p_lock);
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}
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/**
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* req_done - callback which signals activity from the server
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* @vq: virtio queue activity was received on
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*
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* This notifies us that the server has triggered some activity
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* on the virtio channel - most likely a response to request we
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* sent. Figure out which requests now have responses and wake up
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* those threads.
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*
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* Bugs: could do with some additional sanity checking, but appears to work.
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*
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*/
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static void req_done(struct virtqueue *vq)
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{
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struct virtio_chan *chan = vq->vdev->priv;
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struct p9_fcall *rc;
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unsigned int len;
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struct p9_req_t *req;
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unsigned long flags;
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P9_DPRINTK(P9_DEBUG_TRANS, ": request done\n");
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while (1) {
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spin_lock_irqsave(&chan->lock, flags);
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rc = virtqueue_get_buf(chan->vq, &len);
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if (rc == NULL) {
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spin_unlock_irqrestore(&chan->lock, flags);
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break;
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}
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chan->ring_bufs_avail = 1;
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spin_unlock_irqrestore(&chan->lock, flags);
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/* Wakeup if anyone waiting for VirtIO ring space. */
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wake_up(chan->vc_wq);
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P9_DPRINTK(P9_DEBUG_TRANS, ": rc %p\n", rc);
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P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag);
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req = p9_tag_lookup(chan->client, rc->tag);
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if (req->tc->private) {
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struct trans_rpage_info *rp = req->tc->private;
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int p = rp->rp_nr_pages;
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/*Release pages */
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p9_release_req_pages(rp);
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atomic_sub(p, &vp_pinned);
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wake_up(&vp_wq);
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if (rp->rp_alloc)
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kfree(rp);
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req->tc->private = NULL;
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}
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req->status = REQ_STATUS_RCVD;
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p9_client_cb(chan->client, req);
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}
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}
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/**
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* pack_sg_list - pack a scatter gather list from a linear buffer
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* @sg: scatter/gather list to pack into
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* @start: which segment of the sg_list to start at
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* @limit: maximum segment to pack data to
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* @data: data to pack into scatter/gather list
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* @count: amount of data to pack into the scatter/gather list
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*
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* sg_lists have multiple segments of various sizes. This will pack
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* arbitrary data into an existing scatter gather list, segmenting the
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* data as necessary within constraints.
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*
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*/
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static int
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pack_sg_list(struct scatterlist *sg, int start, int limit, char *data,
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int count)
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{
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int s;
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int index = start;
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while (count) {
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s = rest_of_page(data);
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if (s > count)
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s = count;
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sg_set_buf(&sg[index++], data, s);
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count -= s;
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data += s;
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BUG_ON(index > limit);
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}
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return index-start;
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}
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/* We don't currently allow canceling of virtio requests */
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static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
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{
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return 1;
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}
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/**
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* pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer,
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* this takes a list of pages.
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* @sg: scatter/gather list to pack into
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* @start: which segment of the sg_list to start at
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* @pdata_off: Offset into the first page
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* @**pdata: a list of pages to add into sg.
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* @count: amount of data to pack into the scatter/gather list
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*/
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static int
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pack_sg_list_p(struct scatterlist *sg, int start, int limit, size_t pdata_off,
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struct page **pdata, int count)
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{
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int s;
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int i = 0;
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int index = start;
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if (pdata_off) {
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s = min((int)(PAGE_SIZE - pdata_off), count);
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sg_set_page(&sg[index++], pdata[i++], s, pdata_off);
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count -= s;
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}
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while (count) {
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BUG_ON(index > limit);
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s = min((int)PAGE_SIZE, count);
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sg_set_page(&sg[index++], pdata[i++], s, 0);
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count -= s;
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}
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return index-start;
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}
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/**
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* p9_virtio_request - issue a request
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* @client: client instance issuing the request
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* @req: request to be issued
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*
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*/
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static int
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p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
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{
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int in, out, inp, outp;
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struct virtio_chan *chan = client->trans;
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char *rdata = (char *)req->rc+sizeof(struct p9_fcall);
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unsigned long flags;
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size_t pdata_off = 0;
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struct trans_rpage_info *rpinfo = NULL;
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int err, pdata_len = 0;
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P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n");
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req->status = REQ_STATUS_SENT;
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if (req->tc->pbuf_size && (req->tc->pubuf && P9_IS_USER_CONTEXT)) {
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int nr_pages = p9_nr_pages(req);
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int rpinfo_size = sizeof(struct trans_rpage_info) +
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sizeof(struct page *) * nr_pages;
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if (atomic_read(&vp_pinned) >= chan->p9_max_pages) {
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err = wait_event_interruptible(vp_wq,
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atomic_read(&vp_pinned) < chan->p9_max_pages);
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if (err == -ERESTARTSYS)
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return err;
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P9_DPRINTK(P9_DEBUG_TRANS, "9p: May gup pages now.\n");
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}
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if (rpinfo_size <= (req->tc->capacity - req->tc->size)) {
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/* We can use sdata */
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req->tc->private = req->tc->sdata + req->tc->size;
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rpinfo = (struct trans_rpage_info *)req->tc->private;
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rpinfo->rp_alloc = 0;
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} else {
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req->tc->private = kmalloc(rpinfo_size, GFP_NOFS);
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if (!req->tc->private) {
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P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: "
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"private kmalloc returned NULL");
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return -ENOMEM;
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}
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rpinfo = (struct trans_rpage_info *)req->tc->private;
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rpinfo->rp_alloc = 1;
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}
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err = p9_payload_gup(req, &pdata_off, &pdata_len, nr_pages,
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req->tc->id == P9_TREAD ? 1 : 0);
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if (err < 0) {
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if (rpinfo->rp_alloc)
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kfree(rpinfo);
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return err;
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} else {
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atomic_add(rpinfo->rp_nr_pages, &vp_pinned);
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}
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}
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req_retry_pinned:
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spin_lock_irqsave(&chan->lock, flags);
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/* Handle out VirtIO ring buffers */
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out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, req->tc->sdata,
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req->tc->size);
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if (req->tc->pbuf_size && (req->tc->id == P9_TWRITE)) {
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/* We have additional write payload buffer to take care */
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if (req->tc->pubuf && P9_IS_USER_CONTEXT) {
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outp = pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM,
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pdata_off, rpinfo->rp_data, pdata_len);
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} else {
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char *pbuf;
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if (req->tc->pubuf)
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pbuf = (__force char *) req->tc->pubuf;
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else
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pbuf = req->tc->pkbuf;
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outp = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, pbuf,
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req->tc->pbuf_size);
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}
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out += outp;
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}
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/* Handle in VirtIO ring buffers */
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if (req->tc->pbuf_size &&
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((req->tc->id == P9_TREAD) || (req->tc->id == P9_TREADDIR))) {
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/*
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* Take care of additional Read payload.
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* 11 is the read/write header = PDU Header(7) + IO Size (4).
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* Arrange in such a way that server places header in the
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* alloced memory and payload onto the user buffer.
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*/
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inp = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, rdata, 11);
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/*
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* Running executables in the filesystem may result in
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* a read request with kernel buffer as opposed to user buffer.
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*/
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if (req->tc->pubuf && P9_IS_USER_CONTEXT) {
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in = pack_sg_list_p(chan->sg, out+inp, VIRTQUEUE_NUM,
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pdata_off, rpinfo->rp_data, pdata_len);
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} else {
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char *pbuf;
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if (req->tc->pubuf)
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pbuf = (__force char *) req->tc->pubuf;
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else
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pbuf = req->tc->pkbuf;
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in = pack_sg_list(chan->sg, out+inp, VIRTQUEUE_NUM,
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pbuf, req->tc->pbuf_size);
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}
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in += inp;
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} else {
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in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, rdata,
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client->msize);
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}
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err = virtqueue_add_buf(chan->vq, chan->sg, out, in, req->tc);
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if (err < 0) {
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if (err == -ENOSPC) {
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chan->ring_bufs_avail = 0;
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spin_unlock_irqrestore(&chan->lock, flags);
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err = wait_event_interruptible(*chan->vc_wq,
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chan->ring_bufs_avail);
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if (err == -ERESTARTSYS)
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return err;
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P9_DPRINTK(P9_DEBUG_TRANS, "9p:Retry virtio request\n");
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goto req_retry_pinned;
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} else {
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spin_unlock_irqrestore(&chan->lock, flags);
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P9_DPRINTK(P9_DEBUG_TRANS,
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"9p debug: "
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"virtio rpc add_buf returned failure");
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if (rpinfo && rpinfo->rp_alloc)
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kfree(rpinfo);
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return -EIO;
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}
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}
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virtqueue_kick(chan->vq);
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spin_unlock_irqrestore(&chan->lock, flags);
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P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request kicked\n");
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return 0;
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}
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|
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static ssize_t p9_mount_tag_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct virtio_chan *chan;
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struct virtio_device *vdev;
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|
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vdev = dev_to_virtio(dev);
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chan = vdev->priv;
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return snprintf(buf, chan->tag_len + 1, "%s", chan->tag);
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}
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|
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static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL);
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|
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/**
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* p9_virtio_probe - probe for existence of 9P virtio channels
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* @vdev: virtio device to probe
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*
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* This probes for existing virtio channels.
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*
|
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*/
|
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|
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static int p9_virtio_probe(struct virtio_device *vdev)
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{
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__u16 tag_len;
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char *tag;
|
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int err;
|
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struct virtio_chan *chan;
|
|
|
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chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL);
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if (!chan) {
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printk(KERN_ERR "9p: Failed to allocate virtio 9P channel\n");
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err = -ENOMEM;
|
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goto fail;
|
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}
|
|
|
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chan->vdev = vdev;
|
|
|
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/* We expect one virtqueue, for requests. */
|
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chan->vq = virtio_find_single_vq(vdev, req_done, "requests");
|
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if (IS_ERR(chan->vq)) {
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err = PTR_ERR(chan->vq);
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goto out_free_vq;
|
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}
|
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chan->vq->vdev->priv = chan;
|
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spin_lock_init(&chan->lock);
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|
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sg_init_table(chan->sg, VIRTQUEUE_NUM);
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|
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chan->inuse = false;
|
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if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) {
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vdev->config->get(vdev,
|
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offsetof(struct virtio_9p_config, tag_len),
|
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&tag_len, sizeof(tag_len));
|
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} else {
|
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err = -EINVAL;
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goto out_free_vq;
|
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}
|
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tag = kmalloc(tag_len, GFP_KERNEL);
|
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if (!tag) {
|
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err = -ENOMEM;
|
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goto out_free_vq;
|
|
}
|
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vdev->config->get(vdev, offsetof(struct virtio_9p_config, tag),
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tag, tag_len);
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chan->tag = tag;
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chan->tag_len = tag_len;
|
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err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
|
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if (err) {
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goto out_free_tag;
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}
|
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chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL);
|
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if (!chan->vc_wq) {
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err = -ENOMEM;
|
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goto out_free_tag;
|
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}
|
|
init_waitqueue_head(chan->vc_wq);
|
|
chan->ring_bufs_avail = 1;
|
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/* Ceiling limit to avoid denial of service attacks */
|
|
chan->p9_max_pages = nr_free_buffer_pages()/4;
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|
|
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mutex_lock(&virtio_9p_lock);
|
|
list_add_tail(&chan->chan_list, &virtio_chan_list);
|
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mutex_unlock(&virtio_9p_lock);
|
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return 0;
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|
|
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out_free_tag:
|
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kfree(tag);
|
|
out_free_vq:
|
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vdev->config->del_vqs(vdev);
|
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kfree(chan);
|
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fail:
|
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return err;
|
|
}
|
|
|
|
|
|
/**
|
|
* p9_virtio_create - allocate a new virtio channel
|
|
* @client: client instance invoking this transport
|
|
* @devname: string identifying the channel to connect to (unused)
|
|
* @args: args passed from sys_mount() for per-transport options (unused)
|
|
*
|
|
* This sets up a transport channel for 9p communication. Right now
|
|
* we only match the first available channel, but eventually we couldlook up
|
|
* alternate channels by matching devname versus a virtio_config entry.
|
|
* We use a simple reference count mechanism to ensure that only a single
|
|
* mount has a channel open at a time.
|
|
*
|
|
*/
|
|
|
|
static int
|
|
p9_virtio_create(struct p9_client *client, const char *devname, char *args)
|
|
{
|
|
struct virtio_chan *chan;
|
|
int ret = -ENOENT;
|
|
int found = 0;
|
|
|
|
mutex_lock(&virtio_9p_lock);
|
|
list_for_each_entry(chan, &virtio_chan_list, chan_list) {
|
|
if (!strncmp(devname, chan->tag, chan->tag_len) &&
|
|
strlen(devname) == chan->tag_len) {
|
|
if (!chan->inuse) {
|
|
chan->inuse = true;
|
|
found = 1;
|
|
break;
|
|
}
|
|
ret = -EBUSY;
|
|
}
|
|
}
|
|
mutex_unlock(&virtio_9p_lock);
|
|
|
|
if (!found) {
|
|
printk(KERN_ERR "9p: no channels available\n");
|
|
return ret;
|
|
}
|
|
|
|
client->trans = (void *)chan;
|
|
client->status = Connected;
|
|
chan->client = client;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* p9_virtio_remove - clean up resources associated with a virtio device
|
|
* @vdev: virtio device to remove
|
|
*
|
|
*/
|
|
|
|
static void p9_virtio_remove(struct virtio_device *vdev)
|
|
{
|
|
struct virtio_chan *chan = vdev->priv;
|
|
|
|
BUG_ON(chan->inuse);
|
|
vdev->config->del_vqs(vdev);
|
|
|
|
mutex_lock(&virtio_9p_lock);
|
|
list_del(&chan->chan_list);
|
|
mutex_unlock(&virtio_9p_lock);
|
|
sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
|
|
kfree(chan->tag);
|
|
kfree(chan->vc_wq);
|
|
kfree(chan);
|
|
|
|
}
|
|
|
|
static struct virtio_device_id id_table[] = {
|
|
{ VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
|
|
{ 0 },
|
|
};
|
|
|
|
static unsigned int features[] = {
|
|
VIRTIO_9P_MOUNT_TAG,
|
|
};
|
|
|
|
/* The standard "struct lguest_driver": */
|
|
static struct virtio_driver p9_virtio_drv = {
|
|
.feature_table = features,
|
|
.feature_table_size = ARRAY_SIZE(features),
|
|
.driver.name = KBUILD_MODNAME,
|
|
.driver.owner = THIS_MODULE,
|
|
.id_table = id_table,
|
|
.probe = p9_virtio_probe,
|
|
.remove = p9_virtio_remove,
|
|
};
|
|
|
|
static struct p9_trans_module p9_virtio_trans = {
|
|
.name = "virtio",
|
|
.create = p9_virtio_create,
|
|
.close = p9_virtio_close,
|
|
.request = p9_virtio_request,
|
|
.cancel = p9_virtio_cancel,
|
|
.maxsize = PAGE_SIZE*16,
|
|
.pref = P9_TRANS_PREF_PAYLOAD_SEP,
|
|
.def = 0,
|
|
.owner = THIS_MODULE,
|
|
};
|
|
|
|
/* The standard init function */
|
|
static int __init p9_virtio_init(void)
|
|
{
|
|
INIT_LIST_HEAD(&virtio_chan_list);
|
|
|
|
v9fs_register_trans(&p9_virtio_trans);
|
|
return register_virtio_driver(&p9_virtio_drv);
|
|
}
|
|
|
|
static void __exit p9_virtio_cleanup(void)
|
|
{
|
|
unregister_virtio_driver(&p9_virtio_drv);
|
|
v9fs_unregister_trans(&p9_virtio_trans);
|
|
}
|
|
|
|
module_init(p9_virtio_init);
|
|
module_exit(p9_virtio_cleanup);
|
|
|
|
MODULE_DEVICE_TABLE(virtio, id_table);
|
|
MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
|
|
MODULE_DESCRIPTION("Virtio 9p Transport");
|
|
MODULE_LICENSE("GPL");
|