1 files changed, 95 insertions, 52 deletions

diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index ea1e3daabefe..7eb78ecc1618 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -37,6 +37,7 @@
 #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>
@@ -49,8 +50,6 @@
 
 /* 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
@@ -68,8 +67,7 @@ static int chan_index;
  *
  */
 
-static struct virtio_chan {
-        bool initialized;
+struct virtio_chan {
         bool inuse;
 
         spinlock_t lock;
@@ -80,7 +78,17 @@ static struct virtio_chan {
 
         /* Scatterlist: can be too big for stack. */
         struct scatterlist sg[VIRTQUEUE_NUM];
-} channels[MAX_9P_CHAN];
+
+        int tag_len;
+        /*
+         * tag name to identify a mount Non-null terminated
+         */
+        char *tag;
+
+        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)
@@ -102,7 +110,8 @@ static void p9_virtio_close(struct p9_client *client)
         struct virtio_chan *chan = client->trans;
 
         mutex_lock(&virtio_9p_lock);
-        chan->inuse = false;
+        if (chan)
+                chan->inuse = false;
         mutex_unlock(&virtio_9p_lock);
 }
 
@@ -212,30 +221,38 @@ p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
         return 0;
 }
 
+static ssize_t p9_mount_tag_show(struct device *dev,
+                                struct device_attribute *attr, char *buf)
+{
+        struct virtio_chan *chan;
+        struct virtio_device *vdev;
+
+        vdev = dev_to_virtio(dev);
+        chan = vdev->priv;
+
+        return snprintf(buf, chan->tag_len + 1, "%s", chan->tag);
+}
+
+static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL);
+
 /**
  * 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.
+ * This probes for existing virtio channels.
  *
  */
 
 static int p9_virtio_probe(struct virtio_device *vdev)
 {
+        __u16 tag_len;
+        char *tag;
         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();
+        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;
         }
@@ -254,15 +271,37 @@ static int p9_virtio_probe(struct virtio_device *vdev)
         sg_init_table(chan->sg, VIRTQUEUE_NUM);
 
         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;
 
 out_free_vq:
         vdev->config->del_vqs(vdev);
+        kfree(chan);
 fail:
-        mutex_lock(&virtio_9p_lock);
-        chan_index--;
-        mutex_unlock(&virtio_9p_lock);
         return err;
 }
 
@@ -279,38 +318,35 @@ fail:
  * 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;
+        struct virtio_chan *chan;
+        int ret = -ENOENT;
+        int found = 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];
+        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;
                 }
         }
         mutex_unlock(&virtio_9p_lock);
 
-        if (index >= MAX_9P_CHAN) {
+        if (!found) {
                 printk(KERN_ERR "9p: no channels available\n");
-                return -ENODEV;
+                return ret;
         }
 
         client->trans = (void *)chan;
+        client->status = Connected;
         chan->client = client;
 
         return 0;
@@ -327,11 +363,15 @@ 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);
 
-        if (chan->initialized) {
-                vdev->config->del_vqs(vdev);
-                chan->initialized = false;
-        }
 }
 
 static struct virtio_device_id id_table[] = {
@@ -339,13 +379,19 @@ static struct virtio_device_id id_table[] = {
         { 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,
-        .remove =       p9_virtio_remove,
+        .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 = {
@@ -362,10 +408,7 @@ static struct p9_trans_module p9_virtio_trans = {
 /* 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);