/*
- * The Guest 9p transport driver
+ * The Virtio 9p transport driver
*
* This is a block based transport driver based on the lguest block driver
* code.
*
- */
-/*
- * 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/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_ids.h>
#include <linux/virtio_9p.h>
#define VIRTQUEUE_NUM 128
/* a single mutex to manage channel initialization and attachment */
-static DECLARE_MUTEX(virtio_9p_lock);
+static DEFINE_MUTEX(virtio_9p_lock);
/* global which tracks highest initialized channel */
static int chan_index;
-#define P9_INIT_MAXTAG 16
-
-#define REQ_STATUS_IDLE 0
-#define REQ_STATUS_SENT 1
-#define REQ_STATUS_RCVD 2
-#define REQ_STATUS_FLSH 3
-
-struct p9_req_t {
- int status;
- wait_queue_head_t *wq;
-};
-
-/* We keep all per-channel information in a structure.
+/**
+ * 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 */
+ bool initialized;
+ bool inuse;
spinlock_t lock;
+ struct p9_client *client;
struct virtio_device *vdev;
struct virtqueue *vq;
- struct p9_idpool *tagpool;
- struct p9_req_t *reqs;
- int max_tag;
-
/* Scatterlist: can be too big for stack. */
struct scatterlist sg[VIRTQUEUE_NUM];
} channels[MAX_9P_CHAN];
-/* Lookup requests by tag */
-static struct p9_req_t *p9_lookup_tag(struct virtio_chan *c, u16 tag)
-{
- /* This looks up the original request by tag so we know which
- * buffer to read the data into */
- tag++;
-
- while (tag >= c->max_tag) {
- int old_max = c->max_tag;
- int count;
-
- if (c->max_tag)
- c->max_tag *= 2;
- else
- c->max_tag = P9_INIT_MAXTAG;
-
- c->reqs = krealloc(c->reqs, sizeof(struct p9_req_t)*c->max_tag,
- GFP_ATOMIC);
- if (!c->reqs) {
- printk(KERN_ERR "Couldn't grow tag array\n");
- BUG();
- }
- for (count = old_max; count < c->max_tag; count++) {
- c->reqs[count].status = REQ_STATUS_IDLE;
- c->reqs[count].wq = kmalloc(sizeof(wait_queue_t),
- GFP_ATOMIC);
- if (!c->reqs[count].wq) {
- printk(KERN_ERR "Couldn't grow tag array\n");
- BUG();
- }
- init_waitqueue_head(c->reqs[count].wq);
- }
- }
-
- return &c->reqs[tag];
-}
-
-
/* 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)
-{
- /* Only use the rpc mechanism for now */
- return count;
-}
-
-static int p9_virtio_read(struct p9_trans *trans, void *buf, int count)
-{
- /* Only use the rpc mechanism for now */
- return 0;
-}
-
-/* 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_close - reclaim resources of a channel
+ * @client: client instance
+ *
+ * This reclaims a channel by freeing its resources and
+ * reseting its inuse flag.
+ *
*/
-static unsigned int
-p9_virtio_poll(struct p9_trans *trans, struct poll_table_struct *pt)
-{
- /* Only use the rpc mechanism for now */
- return 0;
-}
-static void p9_virtio_close(struct p9_trans *trans)
+static void p9_virtio_close(struct p9_client *client)
{
- struct virtio_chan *chan = trans->priv;
- int count;
- unsigned int flags;
-
- spin_lock_irqsave(&chan->lock, flags);
- p9_idpool_destroy(chan->tagpool);
- for (count = 0; count < chan->max_tag; count++)
- kfree(chan->reqs[count].wq);
- kfree(chan->reqs);
- chan->max_tag = 0;
- spin_unlock_irqrestore(&chan->lock, flags);
+ struct virtio_chan *chan = client->trans;
- down(&virtio_9p_lock);
+ mutex_lock(&virtio_9p_lock);
chan->inuse = false;
- up(&virtio_9p_lock);
-
- kfree(trans);
+ 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;
- unsigned long flags;
struct p9_req_t *req;
- spin_lock_irqsave(&chan->lock, flags);
+ P9_DPRINTK(P9_DEBUG_TRANS, ": request done\n");
+
while ((rc = chan->vq->vq_ops->get_buf(chan->vq, &len)) != NULL) {
- req = p9_lookup_tag(chan, rc->tag);
+ 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;
- wake_up(req->wq);
+ p9_client_cb(chan->client, req);
}
- /* In case queue is stopped waiting for more buffers. */
- spin_unlock_irqrestore(&chan->lock, flags);
}
+/**
+ * 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)
sg_set_buf(&sg[index++], data, s);
count -= s;
data += s;
- if (index > limit)
- BUG();
+ BUG_ON(index > limit);
}
return index-start;
}
-static int
-p9_virtio_rpc(struct p9_trans *t, struct p9_fcall *tc, struct p9_fcall **rc,
- int msize, int dotu)
+/* We don't currently allow canceling of virtio requests */
+static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
{
- int in, out;
- int n, err, size;
- struct virtio_chan *chan = t->priv;
- char *rdata;
- struct p9_req_t *req;
- unsigned long flags;
-
- if (*rc == NULL) {
- *rc = kmalloc(sizeof(struct p9_fcall) + msize, GFP_KERNEL);
- if (!*rc)
- return -ENOMEM;
- }
-
- rdata = (char *)*rc+sizeof(struct p9_fcall);
-
- n = P9_NOTAG;
- if (tc->id != P9_TVERSION) {
- n = p9_idpool_get(chan->tagpool);
- if (n < 0)
- return -ENOMEM;
- }
+ return 1;
+}
- spin_lock_irqsave(&chan->lock, flags);
- req = p9_lookup_tag(chan, n);
- spin_unlock_irqrestore(&chan->lock, flags);
+/**
+ * p9_virtio_request - issue a request
+ * @client: client instance issuing the request
+ * @req: request to be issued
+ *
+ */
- p9_set_tag(tc, n);
+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 rpc tag %d\n", n);
+ P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n");
- out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, tc->sdata, tc->size);
- in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM-out, rdata, msize);
+ 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, tc)) {
+ 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);
- wait_event(*req->wq, req->status == REQ_STATUS_RCVD);
-
- size = le32_to_cpu(*(__le32 *) rdata);
-
- err = p9_deserialize_fcall(rdata, size, *rc, dotu);
- if (err < 0) {
- P9_DPRINTK(P9_DEBUG_TRANS,
- "9p debug: virtio rpc deserialize returned %d\n", err);
- return err;
- }
-
-#ifdef CONFIG_NET_9P_DEBUG
- if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
- char buf[150];
-
- p9_printfcall(buf, sizeof(buf), *rc, dotu);
- printk(KERN_NOTICE ">>> %p %s\n", t, buf);
- }
-#endif
-
- if (n != P9_NOTAG && p9_idpool_check(n, chan->tagpool))
- p9_idpool_put(n, chan->tagpool);
-
- req->status = REQ_STATUS_IDLE;
-
+ 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;
- down(&virtio_9p_lock);
+ mutex_lock(&virtio_9p_lock);
index = chan_index++;
chan = &channels[index];
- up(&virtio_9p_lock);
+ mutex_unlock(&virtio_9p_lock);
if (chan_index > MAX_9P_CHAN) {
printk(KERN_ERR "9p: virtio: Maximum channels exceeded\n");
chan->vdev = vdev;
/* We expect one virtqueue, for requests. */
- chan->vq = vdev->config->find_vq(vdev, 0, req_done);
+ chan->vq = virtio_find_single_vq(vdev, req_done, "requests");
if (IS_ERR(chan->vq)) {
err = PTR_ERR(chan->vq);
goto out_free_vq;
return 0;
out_free_vq:
- vdev->config->del_vq(chan->vq);
+ vdev->config->del_vqs(vdev);
fail:
- down(&virtio_9p_lock);
+ mutex_lock(&virtio_9p_lock);
chan_index--;
- up(&virtio_9p_lock);
+ mutex_unlock(&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.
+ *
+ * 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 p9_trans *trans;
struct virtio_chan *chan = channels;
int index = 0;
- down(&virtio_9p_lock);
+ mutex_lock(&virtio_9p_lock);
while (index < MAX_9P_CHAN) {
if (chan->initialized && !chan->inuse) {
chan->inuse = true;
chan = &channels[index];
}
}
- up(&virtio_9p_lock);
+ mutex_unlock(&virtio_9p_lock);
if (index >= MAX_9P_CHAN) {
printk(KERN_ERR "9p: no channels available\n");
- return ERR_PTR(-ENODEV);
- }
-
- chan->tagpool = p9_idpool_create();
- if (IS_ERR(chan->tagpool)) {
- printk(KERN_ERR "9p: couldn't allocate tagpool\n");
- return ERR_PTR(-ENOMEM);
- }
- p9_idpool_get(chan->tagpool); /* reserve tag 0 */
- chan->max_tag = 0;
- chan->reqs = NULL;
-
- trans = kmalloc(sizeof(struct p9_trans), GFP_KERNEL);
- if (!trans) {
- printk(KERN_ERR "9p: couldn't allocate transport\n");
- return ERR_PTR(-ENOMEM);
+ return -ENODEV;
}
- trans->write = p9_virtio_write;
- trans->read = p9_virtio_read;
- trans->close = p9_virtio_close;
- trans->poll = p9_virtio_poll;
- trans->rpc = p9_virtio_rpc;
- trans->priv = chan;
+ client->trans = (void *)chan;
+ chan->client = client;
- 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);
+
+ if (chan->initialized) {
+ vdev->config->del_vqs(vdev);
+ chan->initialized = false;
+ }
+}
static struct virtio_device_id id_table[] = {
{ VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
.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 */
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