net/9p/trans_virtio.c - maze/linux - Git at Google

 /*
  * The Virtio 9p transport driver
  *
  * This is a block based transport driver based on the lguest block driver
  * code.
  *
  *  Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation
  *
  *  Based on virtio console driver
  *  Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2
  *  as published by the Free Software Foundation.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program; if not, write to:
  *  Free Software Foundation
  *  51 Franklin Street, Fifth Floor
  *  Boston, MA  02111-1301  USA
  *
  */

 #include <linux/in.h>
 #include <linux/module.h>
 #include <linux/net.h>
 #include <linux/ipv6.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/un.h>
 #include <linux/uaccess.h>
 #include <linux/inet.h>
 #include <linux/idr.h>
 #include <linux/file.h>
 #include <net/9p/9p.h>
 #include <linux/parser.h>
 #include <net/9p/client.h>
 #include <net/9p/transport.h>
 #include <linux/scatterlist.h>
 #include <linux/virtio.h>
 #include <linux/virtio_9p.h>

 #define VIRTQUEUE_NUM	128

 /* a single mutex to manage channel initialization and attachment */
 static DEFINE_MUTEX(virtio_9p_lock);
 /* global which tracks highest initialized channel */
 static int chan_index;

 /**
  * struct virtio_chan - per-instance transport information
  * @initialized: whether the channel is initialized
  * @inuse: whether the channel is in use
  * @lock: protects multiple elements within this structure
  * @client: client instance
  * @vdev: virtio dev associated with this channel
  * @vq: virtio queue associated with this channel
  * @sg: scatter gather list which is used to pack a request (protected?)
  *
  * We keep all per-channel information in a structure.
  * This structure is allocated within the devices dev->mem space.
  * A pointer to the structure will get put in the transport private.
  *
  */

 static struct virtio_chan {
 	bool initialized;
 	bool inuse;

 	spinlock_t lock;

 	struct p9_client *client;
 	struct virtio_device *vdev;
 	struct virtqueue *vq;

 	/* Scatterlist: can be too big for stack. */
 	struct scatterlist sg[VIRTQUEUE_NUM];
 } channels[MAX_9P_CHAN];

 /* How many bytes left in this page. */
 static unsigned int rest_of_page(void *data)
 {
 	return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE);
 }

 /**
  * p9_virtio_close - reclaim resources of a channel
  * @client: client instance
  *
  * This reclaims a channel by freeing its resources and
  * reseting its inuse flag.
  *
  */

 static void p9_virtio_close(struct p9_client *client)
 {
 	struct virtio_chan *chan = client->trans;

 	mutex_lock(&virtio_9p_lock);
 	chan->inuse = false;
 	mutex_unlock(&virtio_9p_lock);
 }

 /**
  * req_done - callback which signals activity from the server
  * @vq: virtio queue activity was received on
  *
  * This notifies us that the server has triggered some activity
  * on the virtio channel - most likely a response to request we
  * sent.  Figure out which requests now have responses and wake up
  * those threads.
  *
  * Bugs: could do with some additional sanity checking, but appears to work.
  *
  */

 static void req_done(struct virtqueue *vq)
 {
 	struct virtio_chan *chan = vq->vdev->priv;
 	struct p9_fcall *rc;
 	unsigned int len;
 	struct p9_req_t *req;

 	P9_DPRINTK(P9_DEBUG_TRANS, ": request done\n");

 	while ((rc = chan->vq->vq_ops->get_buf(chan->vq, &len)) != NULL) {
 		P9_DPRINTK(P9_DEBUG_TRANS, ": rc %p\n", rc);
 		P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag);
 		req = p9_tag_lookup(chan->client, rc->tag);
 		req->status = REQ_STATUS_RCVD;
 		p9_client_cb(chan->client, req);
 	}
 }

 /**
  * pack_sg_list - pack a scatter gather list from a linear buffer
  * @sg: scatter/gather list to pack into
  * @start: which segment of the sg_list to start at
  * @limit: maximum segment to pack data to
  * @data: data to pack into scatter/gather list
  * @count: amount of data to pack into the scatter/gather list
  *
  * sg_lists have multiple segments of various sizes.  This will pack
  * arbitrary data into an existing scatter gather list, segmenting the
  * data as necessary within constraints.
  *
  */

 static int
 pack_sg_list(struct scatterlist *sg, int start, int limit, char *data,
 								int count)
 {
 	int s;
 	int index = start;

 	while (count) {
 		s = rest_of_page(data);
 		if (s > count)
 			s = count;
 		sg_set_buf(&sg[index++], data, s);
 		count -= s;
 		data += s;
 		BUG_ON(index > limit);
 	}

 	return index-start;
 }

 /* We don't currently allow canceling of virtio requests */
 static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
 {
 	return 1;
 }

 /**
  * p9_virtio_request - issue a request
  * @client: client instance issuing the request
  * @req: request to be issued
  *
  */

 static int
 p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
 {
 	int in, out;
 	struct virtio_chan *chan = client->trans;
 	char *rdata = (char *)req->rc+sizeof(struct p9_fcall);

 	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n");

 	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->status = REQ_STATUS_SENT;

 	if (chan->vq->vq_ops->add_buf(chan->vq, chan->sg, out, in, req->tc) < 0) {
 		P9_DPRINTK(P9_DEBUG_TRANS,
 			"9p debug: virtio rpc add_buf returned failure");
 		return -EIO;
 	}

 	chan->vq->vq_ops->kick(chan->vq);

 	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request kicked\n");
 	return 0;
 }

 /**
  * p9_virtio_probe - probe for existence of 9P virtio channels
  * @vdev: virtio device to probe
  *
  * This probes for existing virtio channels.  At present only
  * a single channel is in use, so in the future more work may need
  * to be done here.
  *
  */

 static int p9_virtio_probe(struct virtio_device *vdev)
 {
 	int err;
 	struct virtio_chan *chan;
 	int index;

 	mutex_lock(&virtio_9p_lock);
 	index = chan_index++;
 	chan = &channels[index];
 	mutex_unlock(&virtio_9p_lock);

 	if (chan_index > MAX_9P_CHAN) {
 		printk(KERN_ERR "9p: virtio: Maximum channels exceeded\n");
 		BUG();
 		err = -ENOMEM;
 		goto fail;
 	}

 	chan->vdev = vdev;

 	/* We expect one virtqueue, for requests. */
 	chan->vq = virtio_find_single_vq(vdev, req_done, "requests");
 	if (IS_ERR(chan->vq)) {
 		err = PTR_ERR(chan->vq);
 		goto out_free_vq;
 	}
 	chan->vq->vdev->priv = chan;
 	spin_lock_init(&chan->lock);

 	sg_init_table(chan->sg, VIRTQUEUE_NUM);

 	chan->inuse = false;
 	chan->initialized = true;
 	return 0;

 out_free_vq:
 	vdev->config->del_vqs(vdev);
 fail:
 	mutex_lock(&virtio_9p_lock);
 	chan_index--;
 	mutex_unlock(&virtio_9p_lock);
 	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.
  *
  * Bugs: doesn't allow identification of a specific channel
  * to allocate, channels are allocated sequentially. This was
  * a pragmatic decision to get things rolling, but ideally some
  * way of identifying the channel to attach to would be nice
  * if we are going to support multiple channels.
  *
  */

 static int
 p9_virtio_create(struct p9_client *client, const char *devname, char *args)
 {
 	struct virtio_chan *chan = channels;
 	int index = 0;

 	mutex_lock(&virtio_9p_lock);
 	while (index < MAX_9P_CHAN) {
 		if (chan->initialized && !chan->inuse) {
 			chan->inuse = true;
 			break;
 		} else {
 			index++;
 			chan = &channels[index];
 		}
 	}
 	mutex_unlock(&virtio_9p_lock);

 	if (index >= MAX_9P_CHAN) {
 		printk(KERN_ERR "9p: no channels available\n");
 		return -ENODEV;
 	}

 	client->trans = (void *)chan;
 	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);

 	if (chan->initialized) {
 		vdev->config->del_vqs(vdev);
 		chan->initialized = false;
 	}
 }

 #define VIRTIO_ID_9P 9

 static struct virtio_device_id id_table[] = {
 	{ VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
 	{ 0 },
 };

 /* The standard "struct lguest_driver": */
 static struct virtio_driver p9_virtio_drv = {
 	.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,
 	.def = 0,
 	.owner = THIS_MODULE,
 };

 /* The standard init function */
 static int __init p9_virtio_init(void)
 {
 	int count;

 	for (count = 0; count < MAX_9P_CHAN; count++)
 		channels[count].initialized = false;

 	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");
	/*
	* The Virtio 9p transport driver
	*
	* This is a block based transport driver based on the lguest block driver
	* code.
	*
	* Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation
	*
	* Based on virtio console driver
	* Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2
	* as published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to:
	* Free Software Foundation
	* 51 Franklin Street, Fifth Floor
	* Boston, MA 02111-1301 USA
	*
	*/

	#include <linux/in.h>
	#include <linux/module.h>
	#include <linux/net.h>
	#include <linux/ipv6.h>
	#include <linux/errno.h>
	#include <linux/kernel.h>
	#include <linux/un.h>
	#include <linux/uaccess.h>
	#include <linux/inet.h>
	#include <linux/idr.h>
	#include <linux/file.h>
	#include <net/9p/9p.h>
	#include <linux/parser.h>
	#include <net/9p/client.h>
	#include <net/9p/transport.h>
	#include <linux/scatterlist.h>
	#include <linux/virtio.h>
	#include <linux/virtio_9p.h>

	#define VIRTQUEUE_NUM 128

	/* a single mutex to manage channel initialization and attachment */
	static DEFINE_MUTEX(virtio_9p_lock);
	/* global which tracks highest initialized channel */
	static int chan_index;

	/**
	* struct virtio_chan - per-instance transport information
	* @initialized: whether the channel is initialized
	* @inuse: whether the channel is in use
	* @lock: protects multiple elements within this structure
	* @client: client instance
	* @vdev: virtio dev associated with this channel
	* @vq: virtio queue associated with this channel
	* @sg: scatter gather list which is used to pack a request (protected?)
	*
	* We keep all per-channel information in a structure.
	* This structure is allocated within the devices dev->mem space.
	* A pointer to the structure will get put in the transport private.
	*
	*/

	static struct virtio_chan {
	bool initialized;
	bool inuse;

	spinlock_t lock;

	struct p9_client *client;
	struct virtio_device *vdev;
	struct virtqueue *vq;

	/* Scatterlist: can be too big for stack. */
	struct scatterlist sg[VIRTQUEUE_NUM];
	} channels[MAX_9P_CHAN];

	/* How many bytes left in this page. */
	static unsigned int rest_of_page(void *data)
	{
	return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE);
	}

	/**
	* p9_virtio_close - reclaim resources of a channel
	* @client: client instance
	*
	* This reclaims a channel by freeing its resources and
	* reseting its inuse flag.
	*
	*/

	static void p9_virtio_close(struct p9_client *client)
	{
	struct virtio_chan *chan = client->trans;

	mutex_lock(&virtio_9p_lock);
	chan->inuse = false;
	mutex_unlock(&virtio_9p_lock);
	}

	/**
	* req_done - callback which signals activity from the server
	* @vq: virtio queue activity was received on
	*
	* This notifies us that the server has triggered some activity
	* on the virtio channel - most likely a response to request we
	* sent. Figure out which requests now have responses and wake up
	* those threads.
	*
	* Bugs: could do with some additional sanity checking, but appears to work.
	*
	*/

	static void req_done(struct virtqueue *vq)
	{
	struct virtio_chan *chan = vq->vdev->priv;
	struct p9_fcall *rc;
	unsigned int len;
	struct p9_req_t *req;

	P9_DPRINTK(P9_DEBUG_TRANS, ": request done\n");

	while ((rc = chan->vq->vq_ops->get_buf(chan->vq, &len)) != NULL) {
	P9_DPRINTK(P9_DEBUG_TRANS, ": rc %p\n", rc);
	P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag);
	req = p9_tag_lookup(chan->client, rc->tag);
	req->status = REQ_STATUS_RCVD;
	p9_client_cb(chan->client, req);
	}
	}

	/**
	* pack_sg_list - pack a scatter gather list from a linear buffer
	* @sg: scatter/gather list to pack into
	* @start: which segment of the sg_list to start at
	* @limit: maximum segment to pack data to
	* @data: data to pack into scatter/gather list
	* @count: amount of data to pack into the scatter/gather list
	*
	* sg_lists have multiple segments of various sizes. This will pack
	* arbitrary data into an existing scatter gather list, segmenting the
	* data as necessary within constraints.
	*
	*/

	static int
	pack_sg_list(struct scatterlist sg, int start, int limit, char data,
	int count)
	{
	int s;
	int index = start;

	while (count) {
	s = rest_of_page(data);
	if (s > count)
	s = count;
	sg_set_buf(&sg[index++], data, s);
	count -= s;
	data += s;
	BUG_ON(index > limit);
	}

	return index-start;
	}

	/* We don't currently allow canceling of virtio requests */
	static int p9_virtio_cancel(struct p9_client client, struct p9_req_t req)
	{
	return 1;
	}

	/**
	* p9_virtio_request - issue a request
	* @client: client instance issuing the request
	* @req: request to be issued
	*
	*/

	static int
	p9_virtio_request(struct p9_client client, struct p9_req_t req)
	{
	int in, out;
	struct virtio_chan *chan = client->trans;
	char rdata = (char )req->rc+sizeof(struct p9_fcall);

	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n");

	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->status = REQ_STATUS_SENT;

	if (chan->vq->vq_ops->add_buf(chan->vq, chan->sg, out, in, req->tc) < 0) {
	P9_DPRINTK(P9_DEBUG_TRANS,
	"9p debug: virtio rpc add_buf returned failure");
	return -EIO;
	}

	chan->vq->vq_ops->kick(chan->vq);

	P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request kicked\n");
	return 0;
	}

	/**
	* p9_virtio_probe - probe for existence of 9P virtio channels
	* @vdev: virtio device to probe
	*
	* This probes for existing virtio channels. At present only
	* a single channel is in use, so in the future more work may need
	* to be done here.
	*
	*/

	static int p9_virtio_probe(struct virtio_device *vdev)
	{
	int err;
	struct virtio_chan *chan;
	int index;

	mutex_lock(&virtio_9p_lock);
	index = chan_index++;
	chan = &channels[index];
	mutex_unlock(&virtio_9p_lock);

	if (chan_index > MAX_9P_CHAN) {
	printk(KERN_ERR "9p: virtio: Maximum channels exceeded\n");
	BUG();
	err = -ENOMEM;
	goto fail;
	}

	chan->vdev = vdev;

	/* We expect one virtqueue, for requests. */
	chan->vq = virtio_find_single_vq(vdev, req_done, "requests");
	if (IS_ERR(chan->vq)) {
	err = PTR_ERR(chan->vq);
	goto out_free_vq;
	}
	chan->vq->vdev->priv = chan;
	spin_lock_init(&chan->lock);

	sg_init_table(chan->sg, VIRTQUEUE_NUM);

	chan->inuse = false;
	chan->initialized = true;
	return 0;

	out_free_vq:
	vdev->config->del_vqs(vdev);
	fail:
	mutex_lock(&virtio_9p_lock);
	chan_index--;
	mutex_unlock(&virtio_9p_lock);
	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.
	*
	* Bugs: doesn't allow identification of a specific channel
	* to allocate, channels are allocated sequentially. This was
	* a pragmatic decision to get things rolling, but ideally some
	* way of identifying the channel to attach to would be nice
	* if we are going to support multiple channels.
	*
	*/

	static int
	p9_virtio_create(struct p9_client client, const char devname, char *args)
	{
	struct virtio_chan *chan = channels;
	int index = 0;

	mutex_lock(&virtio_9p_lock);
	while (index < MAX_9P_CHAN) {
	if (chan->initialized && !chan->inuse) {
	chan->inuse = true;
	break;
	} else {
	index++;
	chan = &channels[index];
	}
	}
	mutex_unlock(&virtio_9p_lock);

	if (index >= MAX_9P_CHAN) {
	printk(KERN_ERR "9p: no channels available\n");
	return -ENODEV;
	}

	client->trans = (void *)chan;
	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);

	if (chan->initialized) {
	vdev->config->del_vqs(vdev);
	chan->initialized = false;
	}
	}

	#define VIRTIO_ID_9P 9

	static struct virtio_device_id id_table[] = {
	{ VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
	{ 0 },
	};

	/* The standard "struct lguest_driver": */
	static struct virtio_driver p9_virtio_drv = {
	.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,
	.def = 0,
	.owner = THIS_MODULE,
	};

	/* The standard init function */
	static int __init p9_virtio_init(void)
	{
	int count;

	for (count = 0; count < MAX_9P_CHAN; count++)
	channels[count].initialized = false;

	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");