/*
- * The Guest 9p transport driver
+ * The Virtio 9p transport driver
*
- * This is a trivial pipe-based transport driver based on the lguest console
- * code: we use lguest's DMA mechanism to send bytes out, and register a
- * DMA buffer to receive bytes in. It is assumed to be present and available
- * from the very beginning of boot.
+ * This is a block based transport driver based on the lguest block driver
+ * code.
*
- * This may be have been done by just instaniating another HVC console,
- * but HVC's blocksize of 16 bytes is annoying and painful to performance.
- *
- * A more efficient transport could be built based on the virtio block driver
- * but it requires some changes in the 9p transport model (which are in
- * progress)
- *
- */
-/*
- * Copyright (C) 2007 Eric Van Hensbergen, IBM Corporation
+ * Copyright (C) 2007, 2008 Eric Van Hensbergen, IBM Corporation
*
* Based on virtio console driver
* Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
#include <linux/inet.h>
#include <linux/idr.h>
#include <linux/file.h>
+#include <linux/slab.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>
-/* a single mutex to manage channel initialization and attachment */
-static DECLARE_MUTEX(virtio_9p_lock);
-/* global which tracks highest initialized channel */
-static int chan_index;
+#define VIRTQUEUE_NUM 128
-/* We keep all per-channel information in a structure.
+/* a single mutex to manage channel initialization and attachment */
+static DEFINE_MUTEX(virtio_9p_lock);
+
+/**
+ * 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; /* channel is initialized */
- bool inuse; /* channel is in use */
- struct virtqueue *in_vq, *out_vq;
+struct virtio_chan {
+ 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];
- /* This is our input buffer, and how much data is left in it. */
- unsigned int in_len;
- char *in, *inbuf;
+ int tag_len;
+ /*
+ * tag name to identify a mount Non-null terminated
+ */
+ char *tag;
- wait_queue_head_t wq; /* waitq for buffer */
-} channels[MAX_9P_CHAN];
+ struct list_head chan_list;
+};
+
+static struct list_head virtio_chan_list;
/* How many bytes left in this page. */
static unsigned int rest_of_page(void *data)
return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE);
}
-static int p9_virtio_write(struct p9_trans *trans, void *buf, int count)
-{
- struct virtio_chan *chan = (struct virtio_chan *) trans->priv;
- struct virtqueue *out_vq = chan->out_vq;
- struct scatterlist sg[1];
- unsigned int len;
-
- P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio write (%d)\n", count);
-
- /* keep it simple - make sure we don't overflow a page */
- if (rest_of_page(buf) < count)
- count = rest_of_page(buf);
-
- sg_init_one(sg, buf, count);
-
- /* add_buf wants a token to identify this buffer: we hand it any
- * non-NULL pointer, since there's only ever one buffer. */
- if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) == 0) {
- /* Tell Host to go! */
- out_vq->vq_ops->kick(out_vq);
- /* Chill out until it's done with the buffer. */
- while (!out_vq->vq_ops->get_buf(out_vq, &len))
- cpu_relax();
- }
-
- P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio wrote (%d)\n", count);
-
- /* We're expected to return the amount of data we wrote: all of it. */
- return count;
-}
+/**
+ * p9_virtio_close - reclaim resources of a channel
+ * @client: client instance
+ *
+ * This reclaims a channel by freeing its resources and
+ * reseting its inuse flag.
+ *
+ */
-/* Create a scatter-gather list representing our input buffer and put it in the
- * queue. */
-static void add_inbuf(struct virtio_chan *chan)
+static void p9_virtio_close(struct p9_client *client)
{
- struct scatterlist sg[1];
+ struct virtio_chan *chan = client->trans;
- sg_init_one(sg, chan->inbuf, PAGE_SIZE);
-
- /* We should always be able to add one buffer to an empty queue. */
- if (chan->in_vq->vq_ops->add_buf(chan->in_vq, sg, 0, 1, chan->inbuf))
- BUG();
- chan->in_vq->vq_ops->kick(chan->in_vq);
+ mutex_lock(&virtio_9p_lock);
+ if (chan)
+ chan->inuse = false;
+ mutex_unlock(&virtio_9p_lock);
}
-static int p9_virtio_read(struct p9_trans *trans, void *buf, int count)
-{
- struct virtio_chan *chan = (struct virtio_chan *) trans->priv;
- struct virtqueue *in_vq = chan->in_vq;
+/**
+ * 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.
+ *
+ */
- P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio read (%d)\n", count);
+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;
- /* If we don't have an input queue yet, we can't get input. */
- BUG_ON(!in_vq);
+ P9_DPRINTK(P9_DEBUG_TRANS, ": request done\n");
- /* No buffer? Try to get one. */
- if (!chan->in_len) {
- chan->in = in_vq->vq_ops->get_buf(in_vq, &chan->in_len);
- if (!chan->in)
- return 0;
+ 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);
}
+}
- /* You want more than we have to give? Well, try wanting less! */
- if (chan->in_len < count)
- count = chan->in_len;
-
- /* Copy across to their buffer and increment offset. */
- memcpy(buf, chan->in, count);
- chan->in += count;
- chan->in_len -= count;
+/**
+ * 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.
+ *
+ */
- /* Finished? Re-register buffer so Host will use it again. */
- if (chan->in_len == 0)
- add_inbuf(chan);
+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);
+ }
- P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio finished read (%d)\n",
- count);
+ return index-start;
+}
- return count;
+/* 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;
}
-/* The poll function is used by 9p transports to determine if there
- * is there is activity available on a particular channel. In our case
- * we use it to wait for a callback from the input routines.
+/**
+ * p9_virtio_request - issue a request
+ * @client: client instance issuing the request
+ * @req: request to be issued
+ *
*/
-static unsigned int
-p9_virtio_poll(struct p9_trans *trans, struct poll_table_struct *pt)
+
+static int
+p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
{
- struct virtio_chan *chan = (struct virtio_chan *)trans->priv;
- struct virtqueue *in_vq = chan->in_vq;
- int ret = POLLOUT; /* we can always handle more output */
+ int in, out;
+ struct virtio_chan *chan = client->trans;
+ char *rdata = (char *)req->rc+sizeof(struct p9_fcall);
- poll_wait(NULL, &chan->wq, pt);
+ P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n");
- /* No buffer? Try to get one. */
- if (!chan->in_len)
- chan->in = in_vq->vq_ops->get_buf(in_vq, &chan->in_len);
+ 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);
- if (chan->in_len)
- ret |= POLLIN;
+ req->status = REQ_STATUS_SENT;
- return ret;
+ 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;
}
-static void p9_virtio_close(struct p9_trans *trans)
+static ssize_t p9_mount_tag_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
{
- struct virtio_chan *chan = trans->priv;
+ struct virtio_chan *chan;
+ struct virtio_device *vdev;
- down(&virtio_9p_lock);
- chan->inuse = false;
- up(&virtio_9p_lock);
+ vdev = dev_to_virtio(dev);
+ chan = vdev->priv;
- kfree(trans);
+ return snprintf(buf, chan->tag_len + 1, "%s", chan->tag);
}
-static void p9_virtio_intr(struct virtqueue *q)
-{
- struct virtio_chan *chan = q->vdev->priv;
+static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL);
- P9_DPRINTK(P9_DEBUG_TRANS, "9p poll_wakeup: %p\n", &chan->wq);
- wake_up_interruptible(&chan->wq);
-}
+/**
+ * p9_virtio_probe - probe for existence of 9P virtio channels
+ * @vdev: virtio device to probe
+ *
+ * This probes for existing virtio channels.
+ *
+ */
-static int p9_virtio_probe(struct virtio_device *dev)
+static int p9_virtio_probe(struct virtio_device *vdev)
{
+ __u16 tag_len;
+ char *tag;
int err;
struct virtio_chan *chan;
- int index;
- down(&virtio_9p_lock);
- index = chan_index++;
- chan = &channels[index];
- up(&virtio_9p_lock);
-
- if (chan_index > MAX_9P_CHAN) {
- printk(KERN_ERR "9p: virtio: Maximum channels exceeded\n");
- BUG();
- }
-
- chan->vdev = dev;
-
- /* This is the scratch page we use to receive console input */
- chan->inbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
- if (!chan->inbuf) {
+ chan = kmalloc(sizeof(struct virtio_chan), GFP_KERNEL);
+ if (!chan) {
+ printk(KERN_ERR "9p: Failed to allocate virtio 9P channel\n");
err = -ENOMEM;
goto fail;
}
- /* Find the input queue. */
- dev->priv = chan;
- chan->in_vq = dev->config->find_vq(dev, 0, p9_virtio_intr);
- if (IS_ERR(chan->in_vq)) {
- err = PTR_ERR(chan->in_vq);
- goto free;
- }
+ chan->vdev = vdev;
- chan->out_vq = dev->config->find_vq(dev, 1, NULL);
- if (IS_ERR(chan->out_vq)) {
- err = PTR_ERR(chan->out_vq);
- goto free_in_vq;
+ /* 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);
- init_waitqueue_head(&chan->wq);
+ sg_init_table(chan->sg, VIRTQUEUE_NUM);
- /* Register the input buffer the first time. */
- add_inbuf(chan);
chan->inuse = false;
- chan->initialized = true;
-
+ if (virtio_has_feature(vdev, VIRTIO_9P_MOUNT_TAG)) {
+ vdev->config->get(vdev,
+ offsetof(struct virtio_9p_config, tag_len),
+ &tag_len, sizeof(tag_len));
+ } else {
+ err = -EINVAL;
+ goto out_free_vq;
+ }
+ tag = kmalloc(tag_len, GFP_KERNEL);
+ if (!tag) {
+ err = -ENOMEM;
+ goto out_free_vq;
+ }
+ vdev->config->get(vdev, offsetof(struct virtio_9p_config, tag),
+ tag, tag_len);
+ chan->tag = tag;
+ chan->tag_len = tag_len;
+ err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
+ if (err) {
+ kfree(tag);
+ goto out_free_vq;
+ }
+ mutex_lock(&virtio_9p_lock);
+ list_add_tail(&chan->chan_list, &virtio_chan_list);
+ mutex_unlock(&virtio_9p_lock);
return 0;
-free_in_vq:
- dev->config->del_vq(chan->in_vq);
-free:
- kfree(chan->inbuf);
+out_free_vq:
+ vdev->config->del_vqs(vdev);
+ kfree(chan);
fail:
- down(&virtio_9p_lock);
- chan_index--;
- up(&virtio_9p_lock);
return err;
}
-/* This sets up a transport channel for 9p communication. Right now
+
+/**
+ * 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 struct p9_trans *p9_virtio_create(const char *devname, char *args)
+ * mount has a channel open at a time.
+ *
+ */
+
+static int
+p9_virtio_create(struct p9_client *client, const char *devname, char *args)
{
- struct p9_trans *trans;
- int index = 0;
- struct virtio_chan *chan = channels;
-
- down(&virtio_9p_lock);
- while (index < MAX_9P_CHAN) {
- if (chan->initialized && !chan->inuse) {
- chan->inuse = true;
- break;
- } else {
- index++;
- chan = &channels[index];
+ 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)) {
+ if (!chan->inuse) {
+ chan->inuse = true;
+ found = 1;
+ break;
+ }
+ ret = -EBUSY;
}
}
- up(&virtio_9p_lock);
+ mutex_unlock(&virtio_9p_lock);
- if (index >= MAX_9P_CHAN) {
- printk(KERN_ERR "9p: virtio: couldn't find a free channel\n");
- return NULL;
+ if (!found) {
+ printk(KERN_ERR "9p: no channels available\n");
+ return ret;
}
- trans = kmalloc(sizeof(struct p9_trans), GFP_KERNEL);
- if (!trans) {
- printk(KERN_ERR "9p: couldn't allocate transport\n");
- return ERR_PTR(-ENOMEM);
- }
+ client->trans = (void *)chan;
+ client->status = Connected;
+ chan->client = client;
- trans->write = p9_virtio_write;
- trans->read = p9_virtio_read;
- trans->close = p9_virtio_close;
- trans->poll = p9_virtio_poll;
- trans->priv = chan;
-
- return trans;
+ return 0;
}
-#define VIRTIO_ID_9P 9
+/**
+ * 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);
+
+}
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 = {
- .driver.name = KBUILD_MODNAME,
- .driver.owner = THIS_MODULE,
- .id_table = id_table,
- .probe = p9_virtio_probe,
+ .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,
- .maxsize = PAGE_SIZE,
+ .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;
+ 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>");
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff