/* * 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 <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> #define VIRTQUEUE_NUM 128 /* 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. * */ 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]; 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) { 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); if (chan) 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 = virtqueue_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 (virtqueue_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; } virtqueue_kick(chan->vq); P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request kicked\n"); 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. * */ static int p9_virtio_probe(struct virtio_device *vdev) { __u16 tag_len; char *tag; int err; struct virtio_chan *chan; 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; } 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; 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: 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)) { 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); } 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, .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");