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-rw-r--r--net/9p/trans_virtio.c629
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diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
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+++ b/net/9p/trans_virtio.c
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+/*
+ * 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/swap.h>
+#include <linux/virtio.h>
+#include <linux/virtio_9p.h>
+#include "trans_common.h"
+
+#define VIRTQUEUE_NUM 128
+
+/* a single mutex to manage channel initialization and attachment */
+static DEFINE_MUTEX(virtio_9p_lock);
+static DECLARE_WAIT_QUEUE_HEAD(vp_wq);
+static atomic_t vp_pinned = ATOMIC_INIT(0);
+
+/**
+ * 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;
+ int ring_bufs_avail;
+ wait_queue_head_t *vc_wq;
+ /* This is global limit. Since we don't have a global structure,
+ * will be placing it in each channel.
+ */
+ int p9_max_pages;
+ /* 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;
+ unsigned long flags;
+
+ P9_DPRINTK(P9_DEBUG_TRANS, ": request done\n");
+
+ while (1) {
+ spin_lock_irqsave(&chan->lock, flags);
+ rc = virtqueue_get_buf(chan->vq, &len);
+
+ if (rc == NULL) {
+ spin_unlock_irqrestore(&chan->lock, flags);
+ break;
+ }
+
+ chan->ring_bufs_avail = 1;
+ spin_unlock_irqrestore(&chan->lock, flags);
+ /* Wakeup if anyone waiting for VirtIO ring space. */
+ wake_up(chan->vc_wq);
+ 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);
+ if (req->tc->private) {
+ struct trans_rpage_info *rp = req->tc->private;
+ int p = rp->rp_nr_pages;
+ /*Release pages */
+ p9_release_req_pages(rp);
+ atomic_sub(p, &vp_pinned);
+ wake_up(&vp_wq);
+ if (rp->rp_alloc)
+ kfree(rp);
+ req->tc->private = NULL;
+ }
+ 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;
+}
+
+/**
+ * pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer,
+ * this takes a list of pages.
+ * @sg: scatter/gather list to pack into
+ * @start: which segment of the sg_list to start at
+ * @pdata_off: Offset into the first page
+ * @**pdata: a list of pages to add into sg.
+ * @count: amount of data to pack into the scatter/gather list
+ */
+static int
+pack_sg_list_p(struct scatterlist *sg, int start, int limit, size_t pdata_off,
+ struct page **pdata, int count)
+{
+ int s;
+ int i = 0;
+ int index = start;
+
+ if (pdata_off) {
+ s = min((int)(PAGE_SIZE - pdata_off), count);
+ sg_set_page(&sg[index++], pdata[i++], s, pdata_off);
+ count -= s;
+ }
+
+ while (count) {
+ BUG_ON(index > limit);
+ s = min((int)PAGE_SIZE, count);
+ sg_set_page(&sg[index++], pdata[i++], s, 0);
+ count -= s;
+ }
+ return index-start;
+}
+
+/**
+ * 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, inp, outp;
+ struct virtio_chan *chan = client->trans;
+ unsigned long flags;
+ size_t pdata_off = 0;
+ struct trans_rpage_info *rpinfo = NULL;
+ int err, pdata_len = 0;
+
+ P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n");
+
+ req->status = REQ_STATUS_SENT;
+
+ if (req->tc->pbuf_size && (req->tc->pubuf && P9_IS_USER_CONTEXT)) {
+ int nr_pages = p9_nr_pages(req);
+ int rpinfo_size = sizeof(struct trans_rpage_info) +
+ sizeof(struct page *) * nr_pages;
+
+ if (atomic_read(&vp_pinned) >= chan->p9_max_pages) {
+ err = wait_event_interruptible(vp_wq,
+ atomic_read(&vp_pinned) < chan->p9_max_pages);
+ if (err == -ERESTARTSYS)
+ return err;
+ P9_DPRINTK(P9_DEBUG_TRANS, "9p: May gup pages now.\n");
+ }
+
+ if (rpinfo_size <= (req->tc->capacity - req->tc->size)) {
+ /* We can use sdata */
+ req->tc->private = req->tc->sdata + req->tc->size;
+ rpinfo = (struct trans_rpage_info *)req->tc->private;
+ rpinfo->rp_alloc = 0;
+ } else {
+ req->tc->private = kmalloc(rpinfo_size, GFP_NOFS);
+ if (!req->tc->private) {
+ P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: "
+ "private kmalloc returned NULL");
+ return -ENOMEM;
+ }
+ rpinfo = (struct trans_rpage_info *)req->tc->private;
+ rpinfo->rp_alloc = 1;
+ }
+
+ err = p9_payload_gup(req, &pdata_off, &pdata_len, nr_pages,
+ req->tc->id == P9_TREAD ? 1 : 0);
+ if (err < 0) {
+ if (rpinfo->rp_alloc)
+ kfree(rpinfo);
+ return err;
+ } else {
+ atomic_add(rpinfo->rp_nr_pages, &vp_pinned);
+ }
+ }
+
+req_retry_pinned:
+ spin_lock_irqsave(&chan->lock, flags);
+
+ /* Handle out VirtIO ring buffers */
+ out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, req->tc->sdata,
+ req->tc->size);
+
+ if (req->tc->pbuf_size && (req->tc->id == P9_TWRITE)) {
+ /* We have additional write payload buffer to take care */
+ if (req->tc->pubuf && P9_IS_USER_CONTEXT) {
+ outp = pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM,
+ pdata_off, rpinfo->rp_data, pdata_len);
+ } else {
+ char *pbuf;
+ if (req->tc->pubuf)
+ pbuf = (__force char *) req->tc->pubuf;
+ else
+ pbuf = req->tc->pkbuf;
+ outp = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, pbuf,
+ req->tc->pbuf_size);
+ }
+ out += outp;
+ }
+
+ /* Handle in VirtIO ring buffers */
+ if (req->tc->pbuf_size &&
+ ((req->tc->id == P9_TREAD) || (req->tc->id == P9_TREADDIR))) {
+ /*
+ * Take care of additional Read payload.
+ * 11 is the read/write header = PDU Header(7) + IO Size (4).
+ * Arrange in such a way that server places header in the
+ * alloced memory and payload onto the user buffer.
+ */
+ inp = pack_sg_list(chan->sg, out,
+ VIRTQUEUE_NUM, req->rc->sdata, 11);
+ /*
+ * Running executables in the filesystem may result in
+ * a read request with kernel buffer as opposed to user buffer.
+ */
+ if (req->tc->pubuf && P9_IS_USER_CONTEXT) {
+ in = pack_sg_list_p(chan->sg, out+inp, VIRTQUEUE_NUM,
+ pdata_off, rpinfo->rp_data, pdata_len);
+ } else {
+ char *pbuf;
+ if (req->tc->pubuf)
+ pbuf = (__force char *) req->tc->pubuf;
+ else
+ pbuf = req->tc->pkbuf;
+
+ in = pack_sg_list(chan->sg, out+inp, VIRTQUEUE_NUM,
+ pbuf, req->tc->pbuf_size);
+ }
+ in += inp;
+ } else {
+ in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM,
+ req->rc->sdata, req->rc->capacity);
+ }
+
+ err = virtqueue_add_buf(chan->vq, chan->sg, out, in, req->tc);
+ if (err < 0) {
+ if (err == -ENOSPC) {
+ chan->ring_bufs_avail = 0;
+ spin_unlock_irqrestore(&chan->lock, flags);
+ err = wait_event_interruptible(*chan->vc_wq,
+ chan->ring_bufs_avail);
+ if (err == -ERESTARTSYS)
+ return err;
+
+ P9_DPRINTK(P9_DEBUG_TRANS, "9p:Retry virtio request\n");
+ goto req_retry_pinned;
+ } else {
+ spin_unlock_irqrestore(&chan->lock, flags);
+ P9_DPRINTK(P9_DEBUG_TRANS,
+ "9p debug: "
+ "virtio rpc add_buf returned failure");
+ if (rpinfo && rpinfo->rp_alloc)
+ kfree(rpinfo);
+ return -EIO;
+ }
+ }
+
+ virtqueue_kick(chan->vq);
+ spin_unlock_irqrestore(&chan->lock, flags);
+
+ 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) {
+ goto out_free_tag;
+ }
+ chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL);
+ if (!chan->vc_wq) {
+ err = -ENOMEM;
+ goto out_free_tag;
+ }
+ init_waitqueue_head(chan->vc_wq);
+ chan->ring_bufs_avail = 1;
+ /* Ceiling limit to avoid denial of service attacks */
+ chan->p9_max_pages = nr_free_buffer_pages()/4;
+
+ mutex_lock(&virtio_9p_lock);
+ list_add_tail(&chan->chan_list, &virtio_chan_list);
+ mutex_unlock(&virtio_9p_lock);
+ return 0;
+
+out_free_tag:
+ kfree(tag);
+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) &&
+ strlen(devname) == 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->vc_wq);
+ 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,
+
+ /*
+ * We leave one entry for input and one entry for response
+ * headers. We also skip one more entry to accomodate, address
+ * that are not at page boundary, that can result in an extra
+ * page in zero copy.
+ */
+ .maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3),
+ .pref = P9_TRANS_PREF_PAYLOAD_SEP,
+ .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");
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-01 08:06:25 +0000