/*
* virtio-fs glue for FUSE
* Copyright (C) 2018 Red Hat, Inc. and/or its affiliates
*
* Authors:
* Dave Gilbert <dgilbert@redhat.com>
*
* Implements the glue between libfuse and libvhost-user
*
* This program can be distributed under the terms of the GNU LGPLv2.
* See the file COPYING.LIB
*/
#include "qemu/osdep.h"
#include "qemu/iov.h"
#include "fuse_virtio.h"
#include "fuse_i.h"
#include "standard-headers/linux/fuse.h"
#include "fuse_misc.h"
#include "fuse_opt.h"
#include <assert.h>
#include <errno.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/eventfd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/un.h>
#include <unistd.h>
#include "contrib/libvhost-user/libvhost-user.h"
struct fv_VuDev;
struct fv_QueueInfo {
pthread_t thread;
struct fv_VuDev *virtio_dev;
/* Our queue index, corresponds to array position */
int qidx;
int kick_fd;
/* The element for the command currently being processed */
VuVirtqElement *qe;
};
/*
* We pass the dev element into libvhost-user
* and then use it to get back to the outer
* container for other data.
*/
struct fv_VuDev {
VuDev dev;
struct fuse_session *se;
/*
* The following pair of fields are only accessed in the main
* virtio_loop
*/
size_t nqueues;
struct fv_QueueInfo **qi;
};
/* From spec */
struct virtio_fs_config {
char tag[36];
uint32_t num_queues;
};
/* Callback from libvhost-user */
static uint64_t fv_get_features(VuDev *dev)
{
return 1ULL << VIRTIO_F_VERSION_1;
}
/* Callback from libvhost-user */
static void fv_set_features(VuDev *dev, uint64_t features)
{
}
/*
* Callback from libvhost-user if there's a new fd we're supposed to listen
* to, typically a queue kick?
*/
static void fv_set_watch(VuDev *dev, int fd, int condition, vu_watch_cb cb,
void *data)
{
fuse_log(FUSE_LOG_WARNING, "%s: TODO! fd=%d\n", __func__, fd);
}
/*
* Callback from libvhost-user if we're no longer supposed to listen on an fd
*/
static void fv_remove_watch(VuDev *dev, int fd)
{
fuse_log(FUSE_LOG_WARNING, "%s: TODO! fd=%d\n", __func__, fd);
}
/* Callback from libvhost-user to panic */
static void fv_panic(VuDev *dev, const char *err)
{
fuse_log(FUSE_LOG_ERR, "%s: libvhost-user: %s\n", __func__, err);
/* TODO: Allow reconnects?? */
exit(EXIT_FAILURE);
}
/*
* Copy from an iovec into a fuse_buf (memory only)
* Caller must ensure there is space
*/
static void copy_from_iov(struct fuse_buf *buf, size_t out_num,
const struct iovec *out_sg)
{
void *dest = buf->mem;
while (out_num) {
size_t onelen = out_sg->iov_len;
memcpy(dest, out_sg->iov_base, onelen);
dest += onelen;
out_sg++;
out_num--;
}
}
/*
* Copy from one iov to another, the given number of bytes
* The caller must have checked sizes.
*/
static void copy_iov(struct iovec *src_iov, int src_count,
struct iovec *dst_iov, int dst_count, size_t to_copy)
{
size_t dst_offset = 0;
/* Outer loop copies 'src' elements */
while (to_copy) {
assert(src_count);
size_t src_len = src_iov[0].iov_len;
size_t src_offset = 0;
if (src_len > to_copy) {
src_len = to_copy;
}
/* Inner loop copies contents of one 'src' to maybe multiple dst. */
while (src_len) {
assert(dst_count);
size_t dst_len = dst_iov[0].iov_len - dst_offset;
if (dst_len > src_len) {
dst_len = src_len;
}
memcpy(dst_iov[0].iov_base + dst_offset,
src_iov[0].iov_base + src_offset, dst_len);
src_len -= dst_len;
to_copy -= dst_len;
src_offset += dst_len;
dst_offset += dst_len;
assert(dst_offset <= dst_iov[0].iov_len);
if (dst_offset == dst_iov[0].iov_len) {
dst_offset = 0;
dst_iov++;
dst_count--;
}
}
src_iov++;
src_count--;
}
}
/*
* Called back by ll whenever it wants to send a reply/message back
* The 1st element of the iov starts with the fuse_out_header
* 'unique'==0 means it's a notify message.
*/
int virtio_send_msg(struct fuse_session *se, struct fuse_chan *ch,
struct iovec *iov, int count)
{
VuVirtqElement *elem;
VuVirtq *q;
assert(count >= 1);
assert(iov[0].iov_len >= sizeof(struct fuse_out_header));
struct fuse_out_header *out = iov[0].iov_base;
/* TODO: Endianness! */
size_t tosend_len = iov_size(iov, count);
/* unique == 0 is notification, which we don't support */
assert(out->unique);
/* For virtio we always have ch */
assert(ch);
elem = ch->qi->qe;
q = &ch->qi->virtio_dev->dev.vq[ch->qi->qidx];
/* The 'in' part of the elem is to qemu */
unsigned int in_num = elem->in_num;
struct iovec *in_sg = elem->in_sg;
size_t in_len = iov_size(in_sg, in_num);
fuse_log(FUSE_LOG_DEBUG, "%s: elem %d: with %d in desc of length %zd\n",
__func__, elem->index, in_num, in_len);
/*
* The elem should have room for a 'fuse_out_header' (out from fuse)
* plus the data based on the len in the header.
*/
if (in_len < sizeof(struct fuse_out_header)) {
fuse_log(FUSE_LOG_ERR, "%s: elem %d too short for out_header\n",
__func__, elem->index);
return -E2BIG;
}
if (in_len < tosend_len) {
fuse_log(FUSE_LOG_ERR, "%s: elem %d too small for data len %zd\n",
__func__, elem->index, tosend_len);
return -E2BIG;
}
copy_iov(iov, count, in_sg, in_num, tosend_len);
vu_queue_push(&se->virtio_dev->dev, q, elem, tosend_len);
vu_queue_notify(&se->virtio_dev->dev, q);
return 0;
}
/* Thread function for individual queues, created when a queue is 'started' */
static void *fv_queue_thread(void *opaque)
{
struct fv_QueueInfo *qi = opaque;
struct VuDev *dev = &qi->virtio_dev->dev;
struct VuVirtq *q = vu_get_queue(dev, qi->qidx);
struct fuse_session *se = qi->virtio_dev->se;
struct fuse_chan ch;
struct fuse_buf fbuf;
fbuf.mem = NULL;
fbuf.flags = 0;
fuse_mutex_init(&ch.lock);
ch.fd = (int)0xdaff0d111;
ch.qi = qi;
fuse_log(FUSE_LOG_INFO, "%s: Start for queue %d kick_fd %d\n", __func__,
qi->qidx, qi->kick_fd);
while (1) {
struct pollfd pf[1];
pf[0].fd = qi->kick_fd;
pf[0].events = POLLIN;
pf[0].revents = 0;
fuse_log(FUSE_LOG_DEBUG, "%s: Waiting for Queue %d event\n", __func__,
qi->qidx);
int poll_res = ppoll(pf, 1, NULL, NULL);
if (poll_res == -1) {
if (errno == EINTR) {
fuse_log(FUSE_LOG_INFO, "%s: ppoll interrupted, going around\n",
__func__);
continue;
}
fuse_log(FUSE_LOG_ERR, "fv_queue_thread ppoll: %m\n");
break;
}
assert(poll_res == 1);
if (pf[0].revents & (POLLERR | POLLHUP | POLLNVAL)) {
fuse_log(FUSE_LOG_ERR, "%s: Unexpected poll revents %x Queue %d\n",
__func__, pf[0].revents, qi->qidx);
break;
}
assert(pf[0].revents & POLLIN);
fuse_log(FUSE_LOG_DEBUG, "%s: Got queue event on Queue %d\n", __func__,
qi->qidx);
eventfd_t evalue;
if (eventfd_read(qi->kick_fd, &evalue)) {
fuse_log(FUSE_LOG_ERR, "Eventfd_read for queue: %m\n");
break;
}
/* out is from guest, in is too guest */
unsigned int in_bytes, out_bytes;
vu_queue_get_avail_bytes(dev, q, &in_bytes, &out_bytes, ~0, ~0);
fuse_log(FUSE_LOG_DEBUG,
"%s: Queue %d gave evalue: %zx available: in: %u out: %u\n",
__func__, qi->qidx, (size_t)evalue, in_bytes, out_bytes);
while (1) {
/*
* An element contains one request and the space to send our
* response They're spread over multiple descriptors in a
* scatter/gather set and we can't trust the guest to keep them
* still; so copy in/out.
*/
VuVirtqElement *elem = vu_queue_pop(dev, q, sizeof(VuVirtqElement));
if (!elem) {
break;
}
if (!fbuf.mem) {
fbuf.mem = malloc(se->bufsize);
assert(fbuf.mem);
assert(se->bufsize > sizeof(struct fuse_in_header));
}
/* The 'out' part of the elem is from qemu */
unsigned int out_num = elem->out_num;
struct iovec *out_sg = elem->out_sg;
size_t out_len = iov_size(out_sg, out_num);
fuse_log(FUSE_LOG_DEBUG,
"%s: elem %d: with %d out desc of length %zd\n", __func__,
elem->index, out_num, out_len);
/*
* The elem should contain a 'fuse_in_header' (in to fuse)
* plus the data based on the len in the header.
*/
if (out_len < sizeof(struct fuse_in_header)) {
fuse_log(FUSE_LOG_ERR, "%s: elem %d too short for in_header\n",
__func__, elem->index);
assert(0); /* TODO */
}
if (out_len > se->bufsize) {
fuse_log(FUSE_LOG_ERR, "%s: elem %d too large for buffer\n",
__func__, elem->index);
assert(0); /* TODO */
}
copy_from_iov(&fbuf, out_num, out_sg);
fbuf.size = out_len;
/* TODO! Endianness of header */
/* TODO: Add checks for fuse_session_exited */
fuse_session_process_buf_int(se, &fbuf, &ch);
qi->qe = NULL;
free(elem);
elem = NULL;
}
}
pthread_mutex_destroy(&ch.lock);
free(fbuf.mem);
return NULL;
}
/* Callback from libvhost-user on start or stop of a queue */
static void fv_queue_set_started(VuDev *dev, int qidx, bool started)
{
struct fv_VuDev *vud = container_of(dev, struct fv_VuDev, dev);
struct fv_QueueInfo *ourqi;
fuse_log(FUSE_LOG_INFO, "%s: qidx=%d started=%d\n", __func__, qidx,
started);
assert(qidx >= 0);
/*
* Ignore additional request queues for now. passthrough_ll.c must be
* audited for thread-safety issues first. It was written with a
* well-behaved client in mind and may not protect against all types of
* races yet.
*/
if (qidx > 1) {
fuse_log(FUSE_LOG_ERR,
"%s: multiple request queues not yet implemented, please only "
"configure 1 request queue\n",
__func__);
exit(EXIT_FAILURE);
}
if (started) {
/* Fire up a thread to watch this queue */
if (qidx >= vud->nqueues) {
vud->qi = realloc(vud->qi, (qidx + 1) * sizeof(vud->qi[0]));
assert(vud->qi);
memset(vud->qi + vud->nqueues, 0,
sizeof(vud->qi[0]) * (1 + (qidx - vud->nqueues)));
vud->nqueues = qidx + 1;
}
if (!vud->qi[qidx]) {
vud->qi[qidx] = calloc(sizeof(struct fv_QueueInfo), 1);
assert(vud->qi[qidx]);
vud->qi[qidx]->virtio_dev = vud;
vud->qi[qidx]->qidx = qidx;
} else {
/* Shouldn't have been started */
assert(vud->qi[qidx]->kick_fd == -1);
}
ourqi = vud->qi[qidx];
ourqi->kick_fd = dev->vq[qidx].kick_fd;
if (pthread_create(&ourqi->thread, NULL, fv_queue_thread, ourqi)) {
fuse_log(FUSE_LOG_ERR, "%s: Failed to create thread for queue %d\n",
__func__, qidx);
assert(0);
}
} else {
/* TODO: Kill the thread */
assert(qidx < vud->nqueues);
ourqi = vud->qi[qidx];
ourqi->kick_fd = -1;
}
}
static bool fv_queue_order(VuDev *dev, int qidx)
{
return false;
}
static const VuDevIface fv_iface = {
.get_features = fv_get_features,
.set_features = fv_set_features,
/* Don't need process message, we've not got any at vhost-user level */
.queue_set_started = fv_queue_set_started,
.queue_is_processed_in_order = fv_queue_order,
};
/*
* Main loop; this mostly deals with events on the vhost-user
* socket itself, and not actual fuse data.
*/
int virtio_loop(struct fuse_session *se)
{
fuse_log(FUSE_LOG_INFO, "%s: Entry\n", __func__);
while (!fuse_session_exited(se)) {
struct pollfd pf[1];
pf[0].fd = se->vu_socketfd;
pf[0].events = POLLIN;
pf[0].revents = 0;
fuse_log(FUSE_LOG_DEBUG, "%s: Waiting for VU event\n", __func__);
int poll_res = ppoll(pf, 1, NULL, NULL);
if (poll_res == -1) {
if (errno == EINTR) {
fuse_log(FUSE_LOG_INFO, "%s: ppoll interrupted, going around\n",
__func__);
continue;
}
fuse_log(FUSE_LOG_ERR, "virtio_loop ppoll: %m\n");
break;
}
assert(poll_res == 1);
if (pf[0].revents & (POLLERR | POLLHUP | POLLNVAL)) {
fuse_log(FUSE_LOG_ERR, "%s: Unexpected poll revents %x\n", __func__,
pf[0].revents);
break;
}
assert(pf[0].revents & POLLIN);
fuse_log(FUSE_LOG_DEBUG, "%s: Got VU event\n", __func__);
if (!vu_dispatch(&se->virtio_dev->dev)) {
fuse_log(FUSE_LOG_ERR, "%s: vu_dispatch failed\n", __func__);
break;
}
}
fuse_log(FUSE_LOG_INFO, "%s: Exit\n", __func__);
return 0;
}
int virtio_session_mount(struct fuse_session *se)
{
struct sockaddr_un un;
mode_t old_umask;
if (strlen(se->vu_socket_path) >= sizeof(un.sun_path)) {
fuse_log(FUSE_LOG_ERR, "Socket path too long\n");
return -1;
}
se->fd = -1;
/*
* Create the Unix socket to communicate with qemu
* based on QEMU's vhost-user-bridge
*/
unlink(se->vu_socket_path);
strcpy(un.sun_path, se->vu_socket_path);
size_t addr_len = sizeof(un);
int listen_sock = socket(AF_UNIX, SOCK_STREAM, 0);
if (listen_sock == -1) {
fuse_log(FUSE_LOG_ERR, "vhost socket creation: %m\n");
return -1;
}
un.sun_family = AF_UNIX;
/*
* Unfortunately bind doesn't let you set the mask on the socket,
* so set umask to 077 and restore it later.
*/
old_umask = umask(0077);
if (bind(listen_sock, (struct sockaddr *)&un, addr_len) == -1) {
fuse_log(FUSE_LOG_ERR, "vhost socket bind: %m\n");
umask(old_umask);
return -1;
}
umask(old_umask);
if (listen(listen_sock, 1) == -1) {
fuse_log(FUSE_LOG_ERR, "vhost socket listen: %m\n");
return -1;
}
fuse_log(FUSE_LOG_INFO, "%s: Waiting for vhost-user socket connection...\n",
__func__);
int data_sock = accept(listen_sock, NULL, NULL);
if (data_sock == -1) {
fuse_log(FUSE_LOG_ERR, "vhost socket accept: %m\n");
close(listen_sock);
return -1;
}
close(listen_sock);
fuse_log(FUSE_LOG_INFO, "%s: Received vhost-user socket connection\n",
__func__);
/* TODO: Some cleanup/deallocation! */
se->virtio_dev = calloc(sizeof(struct fv_VuDev), 1);
if (!se->virtio_dev) {
fuse_log(FUSE_LOG_ERR, "%s: virtio_dev calloc failed\n", __func__);
close(data_sock);
return -1;
}
se->vu_socketfd = data_sock;
se->virtio_dev->se = se;
vu_init(&se->virtio_dev->dev, 2, se->vu_socketfd, fv_panic, fv_set_watch,
fv_remove_watch, &fv_iface);
return 0;
}
