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b31ff38931
qemu/tools/virtiofsd/fuse_virtio.c
Vivek Goyal b31ff38931 virtiofsd: Get rid of unreachable code in read 
pvreadv() can return following.

- error
- 0 in case of EOF
- short read

We seem to handle all the cases already. We are retrying read in case
of short read. So another check for short read seems like dead code.
Get rid of it.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Connor Kuehl <ckuehl@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20210518213538.693422-3-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2021-05-26 18:39:32 +01:00

1112 lines
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/*
* 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 "qapi/error.h"
#include "fuse_i.h"
#include "standard-headers/linux/fuse.h"
#include "fuse_misc.h"
#include "fuse_opt.h"
#include "fuse_virtio.h"
#include <sys/eventfd.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <grp.h>
#include "libvhost-user.h"
struct fv_VuDev;
struct fv_QueueInfo {
pthread_t thread;
/*
* This lock protects the VuVirtq preventing races between
* fv_queue_thread() and fv_queue_worker().
*/
pthread_mutex_t vq_lock;
struct fv_VuDev *virtio_dev;
/* Our queue index, corresponds to array position */
int qidx;
int kick_fd;
int kill_fd; /* For killing the thread */
};
/* A FUSE request */
typedef struct {
VuVirtqElement elem;
struct fuse_chan ch;
/* Used to complete requests that involve no reply */
bool reply_sent;
} FVRequest;
/*
* 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;
/*
* Either handle virtqueues or vhost-user protocol messages. Don't do
* both at the same time since that could lead to race conditions if
* virtqueues or memory tables change while another thread is accessing
* them.
*
* The assumptions are:
* 1. fv_queue_thread() reads/writes to virtqueues and only reads VuDev.
* 2. virtio_loop() reads/writes virtqueues and VuDev.
*/
pthread_rwlock_t vu_dispatch_rwlock;
/*
* 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 size_t copy_from_iov(struct fuse_buf *buf, size_t out_num,
const struct iovec *out_sg,
size_t max)
{
void *dest = buf->mem;
size_t copied = 0;
while (out_num && max) {
size_t onelen = out_sg->iov_len;
onelen = MIN(onelen, max);
memcpy(dest, out_sg->iov_base, onelen);
dest += onelen;
copied += onelen;
out_sg++;
out_num--;
max -= onelen;
}
return copied;
}
/*
* Skip 'skip' bytes in the iov; 'sg_1stindex' is set as
* the index for the 1st iovec to read data from, and
* 'sg_1stskip' is the number of bytes to skip in that entry.
*
* Returns True if there are at least 'skip' bytes in the iovec
*
*/
static bool skip_iov(const struct iovec *sg, size_t sg_size,
size_t skip,
size_t *sg_1stindex, size_t *sg_1stskip)
{
size_t vec;
for (vec = 0; vec < sg_size; vec++) {
if (sg[vec].iov_len > skip) {
*sg_1stskip = skip;
*sg_1stindex = vec;
return true;
}
skip -= sg[vec].iov_len;
}
*sg_1stindex = vec;
*sg_1stskip = 0;
return skip == 0;
}
/*
* 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--;
}
}
/*
* pthread_rwlock_rdlock() and pthread_rwlock_wrlock can fail if
* a deadlock condition is detected or the current thread already
* owns the lock. They can also fail, like pthread_rwlock_unlock(),
* if the mutex wasn't properly initialized. None of these are ever
* expected to happen.
*/
static void vu_dispatch_rdlock(struct fv_VuDev *vud)
{
int ret = pthread_rwlock_rdlock(&vud->vu_dispatch_rwlock);
assert(ret == 0);
}
static void vu_dispatch_wrlock(struct fv_VuDev *vud)
{
int ret = pthread_rwlock_wrlock(&vud->vu_dispatch_rwlock);
assert(ret == 0);
}
static void vu_dispatch_unlock(struct fv_VuDev *vud)
{
int ret = pthread_rwlock_unlock(&vud->vu_dispatch_rwlock);
assert(ret == 0);
}
/*
* 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)
{
FVRequest *req = container_of(ch, FVRequest, ch);
struct fv_QueueInfo *qi = ch->qi;
VuDev *dev = &se->virtio_dev->dev;
VuVirtq *q = vu_get_queue(dev, qi->qidx);
VuVirtqElement *elem = &req->elem;
int ret = 0;
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);
assert(!req->reply_sent);
/* 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);
ret = -E2BIG;
goto err;
}
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);
ret = -E2BIG;
goto err;
}
copy_iov(iov, count, in_sg, in_num, tosend_len);
vu_dispatch_rdlock(qi->virtio_dev);
pthread_mutex_lock(&qi->vq_lock);
vu_queue_push(dev, q, elem, tosend_len);
vu_queue_notify(dev, q);
pthread_mutex_unlock(&qi->vq_lock);
vu_dispatch_unlock(qi->virtio_dev);
req->reply_sent = true;
err:
return ret;
}
/*
* Callback from fuse_send_data_iov_* when it's virtio and the buffer
* is a single FD with FUSE_BUF_IS_FD | FUSE_BUF_FD_SEEK
* We need send the iov and then the buffer.
* Return 0 on success
*/
int virtio_send_data_iov(struct fuse_session *se, struct fuse_chan *ch,
struct iovec *iov, int count, struct fuse_bufvec *buf,
size_t len)
{
FVRequest *req = container_of(ch, FVRequest, ch);
struct fv_QueueInfo *qi = ch->qi;
VuDev *dev = &se->virtio_dev->dev;
VuVirtq *q = vu_get_queue(dev, qi->qidx);
VuVirtqElement *elem = &req->elem;
int ret = 0;
g_autofree struct iovec *in_sg_cpy = NULL;
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 iov_len = iov_size(iov, count);
size_t tosend_len = iov_len + len;
out->len = tosend_len;
fuse_log(FUSE_LOG_DEBUG, "%s: count=%d len=%zd iov_len=%zd\n", __func__,
count, len, iov_len);
/* unique == 0 is notification which we don't support */
assert(out->unique);
assert(!req->reply_sent);
/* 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);
ret = E2BIG;
goto err;
}
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);
ret = E2BIG;
goto err;
}
/* TODO: Limit to 'len' */
/* First copy the header data from iov->in_sg */
copy_iov(iov, count, in_sg, in_num, iov_len);
/*
* Build a copy of the the in_sg iov so we can skip bits in it,
* including changing the offsets
*/
in_sg_cpy = g_new(struct iovec, in_num);
memcpy(in_sg_cpy, in_sg, sizeof(struct iovec) * in_num);
/* These get updated as we skip */
struct iovec *in_sg_ptr = in_sg_cpy;
int in_sg_cpy_count = in_num;
/* skip over parts of in_sg that contained the header iov */
size_t skip_size = iov_len;
size_t in_sg_left = 0;
do {
while (skip_size != 0 && in_sg_cpy_count) {
if (skip_size >= in_sg_ptr[0].iov_len) {
skip_size -= in_sg_ptr[0].iov_len;
in_sg_ptr++;
in_sg_cpy_count--;
} else {
in_sg_ptr[0].iov_len -= skip_size;
in_sg_ptr[0].iov_base += skip_size;
break;
}
}
int i;
for (i = 0, in_sg_left = 0; i < in_sg_cpy_count; i++) {
in_sg_left += in_sg_ptr[i].iov_len;
}
fuse_log(FUSE_LOG_DEBUG,
"%s: after skip skip_size=%zd in_sg_cpy_count=%d "
"in_sg_left=%zd\n",
__func__, skip_size, in_sg_cpy_count, in_sg_left);
ret = preadv(buf->buf[0].fd, in_sg_ptr, in_sg_cpy_count,
buf->buf[0].pos);
if (ret == -1) {
ret = errno;
if (ret == EINTR) {
continue;
}
fuse_log(FUSE_LOG_DEBUG, "%s: preadv failed (%m) len=%zd\n",
__func__, len);
goto err;
}
fuse_log(FUSE_LOG_DEBUG, "%s: preadv ret=%d len=%zd\n", __func__,
ret, len);
if (ret < len && ret) {
fuse_log(FUSE_LOG_DEBUG, "%s: ret < len\n", __func__);
/* Skip over this much next time around */
skip_size = ret;
buf->buf[0].pos += ret;
len -= ret;
/* Lets do another read */
continue;
}
if (!ret) {
/* EOF case? */
fuse_log(FUSE_LOG_DEBUG, "%s: !ret in_sg_left=%zd\n", __func__,
in_sg_left);
break;
}
in_sg_left -= ret;
len -= ret;
} while (in_sg_left);
/* Need to fix out->len on EOF */
if (len) {
struct fuse_out_header *out_sg = in_sg[0].iov_base;
tosend_len -= len;
out_sg->len = tosend_len;
}
ret = 0;
vu_dispatch_rdlock(qi->virtio_dev);
pthread_mutex_lock(&qi->vq_lock);
vu_queue_push(dev, q, elem, tosend_len);
vu_queue_notify(dev, q);
pthread_mutex_unlock(&qi->vq_lock);
vu_dispatch_unlock(qi->virtio_dev);
err:
if (ret == 0) {
req->reply_sent = true;
}
return ret;
}
static __thread bool clone_fs_called;
/* Process one FVRequest in a thread pool */
static void fv_queue_worker(gpointer data, gpointer user_data)
{
struct fv_QueueInfo *qi = user_data;
struct fuse_session *se = qi->virtio_dev->se;
struct VuDev *dev = &qi->virtio_dev->dev;
FVRequest *req = data;
VuVirtqElement *elem = &req->elem;
struct fuse_buf fbuf = {};
bool allocated_bufv = false;
struct fuse_bufvec bufv;
struct fuse_bufvec *pbufv;
struct fuse_in_header inh;
assert(se->bufsize > sizeof(struct fuse_in_header));
if (!clone_fs_called) {
int ret;
/* unshare FS for xattr operation */
ret = unshare(CLONE_FS);
/* should not fail */
assert(ret == 0);
clone_fs_called = true;
}
/*
* 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.
*/
fbuf.mem = g_malloc(se->bufsize);
fuse_mutex_init(&req->ch.lock);
req->ch.fd = -1;
req->ch.qi = qi;
/* 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 just the fuse_in_header and look at it */
copy_from_iov(&fbuf, out_num, out_sg,
sizeof(struct fuse_in_header));
memcpy(&inh, fbuf.mem, sizeof(struct fuse_in_header));
pbufv = NULL; /* Compiler thinks an unitialised path */
if (inh.opcode == FUSE_WRITE &&
out_len >= (sizeof(struct fuse_in_header) +
sizeof(struct fuse_write_in))) {
/*
* For a write we don't actually need to copy the
* data, we can just do it straight out of guest memory
* but we must still copy the headers in case the guest
* was nasty and changed them while we were using them.
*/
fuse_log(FUSE_LOG_DEBUG, "%s: Write special case\n", __func__);
fbuf.size = copy_from_iov(&fbuf, out_num, out_sg,
sizeof(struct fuse_in_header) +
sizeof(struct fuse_write_in));
/* That copy reread the in_header, make sure we use the original */
memcpy(fbuf.mem, &inh, sizeof(struct fuse_in_header));
/* Allocate the bufv, with space for the rest of the iov */
pbufv = g_try_malloc(sizeof(struct fuse_bufvec) +
sizeof(struct fuse_buf) * out_num);
if (!pbufv) {
fuse_log(FUSE_LOG_ERR, "%s: pbufv malloc failed\n",
__func__);
goto out;
}
allocated_bufv = true;
pbufv->count = 1;
pbufv->buf[0] = fbuf;
size_t iovindex, pbufvindex, iov_bytes_skip;
pbufvindex = 1; /* 2 headers, 1 fusebuf */
if (!skip_iov(out_sg, out_num,
sizeof(struct fuse_in_header) +
sizeof(struct fuse_write_in),
&iovindex, &iov_bytes_skip)) {
fuse_log(FUSE_LOG_ERR, "%s: skip failed\n",
__func__);
goto out;
}
for (; iovindex < out_num; iovindex++, pbufvindex++) {
pbufv->count++;
pbufv->buf[pbufvindex].pos = ~0; /* Dummy */
pbufv->buf[pbufvindex].flags = 0;
pbufv->buf[pbufvindex].mem = out_sg[iovindex].iov_base;
pbufv->buf[pbufvindex].size = out_sg[iovindex].iov_len;
if (iov_bytes_skip) {
pbufv->buf[pbufvindex].mem += iov_bytes_skip;
pbufv->buf[pbufvindex].size -= iov_bytes_skip;
iov_bytes_skip = 0;
}
}
} else {
/* Normal (non fast write) path */
copy_from_iov(&fbuf, out_num, out_sg, se->bufsize);
/* That copy reread the in_header, make sure we use the original */
memcpy(fbuf.mem, &inh, sizeof(struct fuse_in_header));
fbuf.size = out_len;
/* TODO! Endianness of header */
/* TODO: Add checks for fuse_session_exited */
bufv.buf[0] = fbuf;
bufv.count = 1;
pbufv = &bufv;
}
pbufv->idx = 0;
pbufv->off = 0;
fuse_session_process_buf_int(se, pbufv, &req->ch);
out:
if (allocated_bufv) {
g_free(pbufv);
}
/* If the request has no reply, still recycle the virtqueue element */
if (!req->reply_sent) {
struct VuVirtq *q = vu_get_queue(dev, qi->qidx);
fuse_log(FUSE_LOG_DEBUG, "%s: elem %d no reply sent\n", __func__,
elem->index);
vu_dispatch_rdlock(qi->virtio_dev);
pthread_mutex_lock(&qi->vq_lock);
vu_queue_push(dev, q, elem, 0);
vu_queue_notify(dev, q);
pthread_mutex_unlock(&qi->vq_lock);
vu_dispatch_unlock(qi->virtio_dev);
}
pthread_mutex_destroy(&req->ch.lock);
g_free(fbuf.mem);
free(req);
}
/* 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;
GThreadPool *pool = NULL;
GList *req_list = NULL;
if (se->thread_pool_size) {
fuse_log(FUSE_LOG_DEBUG, "%s: Creating thread pool for Queue %d\n",
__func__, qi->qidx);
pool = g_thread_pool_new(fv_queue_worker, qi, se->thread_pool_size,
FALSE, NULL);
if (!pool) {
fuse_log(FUSE_LOG_ERR, "%s: g_thread_pool_new failed\n", __func__);
return NULL;
}
}
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[2];
pf[0].fd = qi->kick_fd;
pf[0].events = POLLIN;
pf[0].revents = 0;
pf[1].fd = qi->kill_fd;
pf[1].events = POLLIN;
pf[1].revents = 0;
fuse_log(FUSE_LOG_DEBUG, "%s: Waiting for Queue %d event\n", __func__,
qi->qidx);
int poll_res = ppoll(pf, 2, 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;
}
if (pf[1].revents & (POLLERR | POLLHUP | POLLNVAL)) {
fuse_log(FUSE_LOG_ERR,
"%s: Unexpected poll revents %x Queue %d killfd\n",
__func__, pf[1].revents, qi->qidx);
break;
}
if (pf[1].revents) {
fuse_log(FUSE_LOG_INFO, "%s: kill event on queue %d - quitting\n",
__func__, 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;
}
/* Mutual exclusion with virtio_loop() */
vu_dispatch_rdlock(qi->virtio_dev);
pthread_mutex_lock(&qi->vq_lock);
/* 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) {
FVRequest *req = vu_queue_pop(dev, q, sizeof(FVRequest));
if (!req) {
break;
}
req->reply_sent = false;
if (!se->thread_pool_size) {
req_list = g_list_prepend(req_list, req);
} else {
g_thread_pool_push(pool, req, NULL);
}
}
pthread_mutex_unlock(&qi->vq_lock);
vu_dispatch_unlock(qi->virtio_dev);
/* Process all the requests. */
if (!se->thread_pool_size && req_list != NULL) {
g_list_foreach(req_list, fv_queue_worker, qi);
g_list_free(req_list);
req_list = NULL;
}
}
if (pool) {
g_thread_pool_free(pool, FALSE, TRUE);
}
return NULL;
}
static void fv_queue_cleanup_thread(struct fv_VuDev *vud, int qidx)
{
int ret;
struct fv_QueueInfo *ourqi;
assert(qidx < vud->nqueues);
ourqi = vud->qi[qidx];
/* Kill the thread */
if (eventfd_write(ourqi->kill_fd, 1)) {
fuse_log(FUSE_LOG_ERR, "Eventfd_write for queue %d: %s\n",
qidx, strerror(errno));
}
ret = pthread_join(ourqi->thread, NULL);
if (ret) {
fuse_log(FUSE_LOG_ERR, "%s: Failed to join thread idx %d err %d\n",
__func__, qidx, ret);
}
pthread_mutex_destroy(&ourqi->vq_lock);
close(ourqi->kill_fd);
ourqi->kick_fd = -1;
g_free(vud->qi[qidx]);
vud->qi[qidx] = 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 = g_realloc_n(vud->qi, qidx + 1, sizeof(vud->qi[0]));
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] = g_new0(struct fv_QueueInfo, 1);
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;
ourqi->kill_fd = eventfd(0, EFD_CLOEXEC | EFD_SEMAPHORE);
assert(ourqi->kill_fd != -1);
pthread_mutex_init(&ourqi->vq_lock, NULL);
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 {
/*
* Temporarily drop write-lock taken in virtio_loop() so that
* the queue thread doesn't block in virtio_send_msg().
*/
vu_dispatch_unlock(vud);
fv_queue_cleanup_thread(vud, qidx);
vu_dispatch_wrlock(vud);
}
}
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];
bool ok;
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__);
/* Mutual exclusion with fv_queue_thread() */
vu_dispatch_wrlock(se->virtio_dev);
ok = vu_dispatch(&se->virtio_dev->dev);
vu_dispatch_unlock(se->virtio_dev);
if (!ok) {
fuse_log(FUSE_LOG_ERR, "%s: vu_dispatch failed\n", __func__);
break;
}
}
/*
* Make sure all fv_queue_thread()s quit on exit, as we're about to
* free virtio dev and fuse session, no one should access them anymore.
*/
for (int i = 0; i < se->virtio_dev->nqueues; i++) {
if (!se->virtio_dev->qi[i]) {
continue;
}
fuse_log(FUSE_LOG_INFO, "%s: Stopping queue %d thread\n", __func__, i);
fv_queue_cleanup_thread(se->virtio_dev, i);
}
fuse_log(FUSE_LOG_INFO, "%s: Exit\n", __func__);
return 0;
}
static void strreplace(char *s, char old, char new)
{
for (; *s; ++s) {
if (*s == old) {
*s = new;
}
}
}
static bool fv_socket_lock(struct fuse_session *se)
{
g_autofree gchar *sk_name = NULL;
g_autofree gchar *pidfile = NULL;
g_autofree gchar *dir = NULL;
Error *local_err = NULL;
dir = qemu_get_local_state_pathname("run/virtiofsd");
if (g_mkdir_with_parents(dir, S_IRWXU) < 0) {
fuse_log(FUSE_LOG_ERR, "%s: Failed to create directory %s: %s",
__func__, dir, strerror(errno));
return false;
}
sk_name = g_strdup(se->vu_socket_path);
strreplace(sk_name, '/', '.');
pidfile = g_strdup_printf("%s/%s.pid", dir, sk_name);
if (!qemu_write_pidfile(pidfile, &local_err)) {
error_report_err(local_err);
return false;
}
return true;
}
static int fv_create_listen_socket(struct fuse_session *se)
{
struct sockaddr_un un;
mode_t old_umask;
/* Nothing to do if fd is already initialized */
if (se->vu_listen_fd >= 0) {
return 0;
}
if (strlen(se->vu_socket_path) >= sizeof(un.sun_path)) {
fuse_log(FUSE_LOG_ERR, "Socket path too long\n");
return -1;
}
if (!strlen(se->vu_socket_path)) {
fuse_log(FUSE_LOG_ERR, "Socket path is empty\n");
return -1;
}
/* Check the vu_socket_path is already used */
if (!fv_socket_lock(se)) {
return -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 appropriately and restore it later.
*/
if (se->vu_socket_group) {
old_umask = umask(S_IROTH | S_IWOTH | S_IXOTH);
} else {
old_umask = umask(S_IRGRP | S_IWGRP | S_IXGRP |
S_IROTH | S_IWOTH | S_IXOTH);
}
if (bind(listen_sock, (struct sockaddr *)&un, addr_len) == -1) {
fuse_log(FUSE_LOG_ERR, "vhost socket bind: %m\n");
close(listen_sock);
umask(old_umask);
return -1;
}
if (se->vu_socket_group) {
struct group *g = getgrnam(se->vu_socket_group);
if (g) {
if (chown(se->vu_socket_path, -1, g->gr_gid) == -1) {
fuse_log(FUSE_LOG_WARNING,
"vhost socket failed to set group to %s (%d): %m\n",
se->vu_socket_group, g->gr_gid);
}
}
}
umask(old_umask);
if (listen(listen_sock, 1) == -1) {
fuse_log(FUSE_LOG_ERR, "vhost socket listen: %m\n");
close(listen_sock);
return -1;
}
se->vu_listen_fd = listen_sock;
return 0;
}
int virtio_session_mount(struct fuse_session *se)
{
int ret;
/*
* Test that unshare(CLONE_FS) works. fv_queue_worker() will need it. It's
* an unprivileged system call but some Docker/Moby versions are known to
* reject it via seccomp when CAP_SYS_ADMIN is not given.
*
* Note that the program is single-threaded here so this syscall has no
* visible effect and is safe to make.
*/
ret = unshare(CLONE_FS);
if (ret == -1 && errno == EPERM) {
fuse_log(FUSE_LOG_ERR, "unshare(CLONE_FS) failed with EPERM. If "
"running in a container please check that the container "
"runtime seccomp policy allows unshare.\n");
return -1;
}
ret = fv_create_listen_socket(se);
if (ret < 0) {
return ret;
}
se->fd = -1;
fuse_log(FUSE_LOG_INFO, "%s: Waiting for vhost-user socket connection...\n",
__func__);
int data_sock = accept(se->vu_listen_fd, NULL, NULL);
if (data_sock == -1) {
fuse_log(FUSE_LOG_ERR, "vhost socket accept: %m\n");
close(se->vu_listen_fd);
return -1;
}
close(se->vu_listen_fd);
se->vu_listen_fd = -1;
fuse_log(FUSE_LOG_INFO, "%s: Received vhost-user socket connection\n",
__func__);
/* TODO: Some cleanup/deallocation! */
se->virtio_dev = g_new0(struct fv_VuDev, 1);
se->vu_socketfd = data_sock;
se->virtio_dev->se = se;
pthread_rwlock_init(&se->virtio_dev->vu_dispatch_rwlock, NULL);
if (!vu_init(&se->virtio_dev->dev, 2, se->vu_socketfd, fv_panic, NULL,
fv_set_watch, fv_remove_watch, &fv_iface)) {
fuse_log(FUSE_LOG_ERR, "%s: vu_init failed\n", __func__);
return -1;
}
return 0;
}
void virtio_session_close(struct fuse_session *se)
{
close(se->vu_socketfd);
if (!se->virtio_dev) {
return;
}
g_free(se->virtio_dev->qi);
pthread_rwlock_destroy(&se->virtio_dev->vu_dispatch_rwlock);
g_free(se->virtio_dev);
se->virtio_dev = NULL;
}
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