Merge remote-tracking branch 'remotes/dgilbert-gitlab/tags/pull-virtiofs-20200123b' into staging

virtiofsd first pull v2

Import our virtiofsd.
This pulls in the daemon to drive a file system connected to the
existing qemu virtiofsd device.
It's derived from upstream libfuse with lots of changes (and a lot
trimmed out).
The daemon lives in the newly created qemu/tools/virtiofsd

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

v2
  drop the docs while we discuss where they should live
  and we need to redo the manpage in anything but texi

# gpg: Signature made Thu 23 Jan 2020 16:45:18 GMT
# gpg:                using RSA key 45F5C71B4A0CB7FB977A9FA90516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>" [full]
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert-gitlab/tags/pull-virtiofs-20200123b: (108 commits)
  virtiofsd: add some options to the help message
  virtiofsd: stop all queue threads on exit in virtio_loop()
  virtiofsd/passthrough_ll: Pass errno to fuse_reply_err()
  virtiofsd: Convert lo_destroy to take the lo->mutex lock itself
  virtiofsd: add --thread-pool-size=NUM option
  virtiofsd: fix lo_destroy() resource leaks
  virtiofsd: prevent FUSE_INIT/FUSE_DESTROY races
  virtiofsd: process requests in a thread pool
  virtiofsd: use fuse_buf_writev to replace fuse_buf_write for better performance
  virtiofsd: add definition of fuse_buf_writev()
  virtiofsd: passthrough_ll: Use cache_readdir for directory open
  virtiofsd: Fix data corruption with O_APPEND write in writeback mode
  virtiofsd: Reset O_DIRECT flag during file open
  virtiofsd: convert more fprintf and perror to use fuse log infra
  virtiofsd: do not always set FUSE_FLOCK_LOCKS
  virtiofsd: introduce inode refcount to prevent use-after-free
  virtiofsd: passthrough_ll: fix refcounting on remove/rename
  libvhost-user: Fix some memtable remap cases
  virtiofsd: rename inode->refcount to inode->nlookup
  virtiofsd: prevent races with lo_dirp_put()
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 2761 insertions, 0 deletions

diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c
new file mode 100644
index 0000000000..de2e2e0c65
--- /dev/null
+++ b/tools/virtiofsd/fuse_lowlevel.c
@@ -0,0 +1,2761 @@
+/*
+ * FUSE: Filesystem in Userspace
+ * Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>
+ *
+ * Implementation of (most of) the low-level FUSE API. The session loop
+ * functions are implemented in separate files.
+ *
+ * This program can be distributed under the terms of the GNU LGPLv2.
+ * See the file COPYING.LIB
+ */
+
+#include "qemu/osdep.h"
+#include "fuse_i.h"
+#include "standard-headers/linux/fuse.h"
+#include "fuse_misc.h"
+#include "fuse_opt.h"
+#include "fuse_virtio.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <glib.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/file.h>
+#include <unistd.h>
+
+#define THREAD_POOL_SIZE 64
+
+#define OFFSET_MAX 0x7fffffffffffffffLL
+
+struct fuse_pollhandle {
+    uint64_t kh;
+    struct fuse_session *se;
+};
+
+static size_t pagesize;
+
+static __attribute__((constructor)) void fuse_ll_init_pagesize(void)
+{
+    pagesize = getpagesize();
+}
+
+static void convert_stat(const struct stat *stbuf, struct fuse_attr *attr)
+{
+    *attr = (struct fuse_attr){
+        .ino = stbuf->st_ino,
+        .mode = stbuf->st_mode,
+        .nlink = stbuf->st_nlink,
+        .uid = stbuf->st_uid,
+        .gid = stbuf->st_gid,
+        .rdev = stbuf->st_rdev,
+        .size = stbuf->st_size,
+        .blksize = stbuf->st_blksize,
+        .blocks = stbuf->st_blocks,
+        .atime = stbuf->st_atime,
+        .mtime = stbuf->st_mtime,
+        .ctime = stbuf->st_ctime,
+        .atimensec = ST_ATIM_NSEC(stbuf),
+        .mtimensec = ST_MTIM_NSEC(stbuf),
+        .ctimensec = ST_CTIM_NSEC(stbuf),
+    };
+}
+
+static void convert_attr(const struct fuse_setattr_in *attr, struct stat *stbuf)
+{
+    stbuf->st_mode = attr->mode;
+    stbuf->st_uid = attr->uid;
+    stbuf->st_gid = attr->gid;
+    stbuf->st_size = attr->size;
+    stbuf->st_atime = attr->atime;
+    stbuf->st_mtime = attr->mtime;
+    stbuf->st_ctime = attr->ctime;
+    ST_ATIM_NSEC_SET(stbuf, attr->atimensec);
+    ST_MTIM_NSEC_SET(stbuf, attr->mtimensec);
+    ST_CTIM_NSEC_SET(stbuf, attr->ctimensec);
+}
+
+static size_t iov_length(const struct iovec *iov, size_t count)
+{
+    size_t seg;
+    size_t ret = 0;
+
+    for (seg = 0; seg < count; seg++) {
+        ret += iov[seg].iov_len;
+    }
+    return ret;
+}
+
+static void list_init_req(struct fuse_req *req)
+{
+    req->next = req;
+    req->prev = req;
+}
+
+static void list_del_req(struct fuse_req *req)
+{
+    struct fuse_req *prev = req->prev;
+    struct fuse_req *next = req->next;
+    prev->next = next;
+    next->prev = prev;
+}
+
+static void list_add_req(struct fuse_req *req, struct fuse_req *next)
+{
+    struct fuse_req *prev = next->prev;
+    req->next = next;
+    req->prev = prev;
+    prev->next = req;
+    next->prev = req;
+}
+
+static void destroy_req(fuse_req_t req)
+{
+    pthread_mutex_destroy(&req->lock);
+    free(req);
+}
+
+void fuse_free_req(fuse_req_t req)
+{
+    int ctr;
+    struct fuse_session *se = req->se;
+
+    pthread_mutex_lock(&se->lock);
+    req->u.ni.func = NULL;
+    req->u.ni.data = NULL;
+    list_del_req(req);
+    ctr = --req->ctr;
+    req->ch = NULL;
+    pthread_mutex_unlock(&se->lock);
+    if (!ctr) {
+        destroy_req(req);
+    }
+}
+
+static struct fuse_req *fuse_ll_alloc_req(struct fuse_session *se)
+{
+    struct fuse_req *req;
+
+    req = (struct fuse_req *)calloc(1, sizeof(struct fuse_req));
+    if (req == NULL) {
+        fuse_log(FUSE_LOG_ERR, "fuse: failed to allocate request\n");
+    } else {
+        req->se = se;
+        req->ctr = 1;
+        list_init_req(req);
+        fuse_mutex_init(&req->lock);
+    }
+
+    return req;
+}
+
+/* Send data. If *ch* is NULL, send via session master fd */
+static int fuse_send_msg(struct fuse_session *se, struct fuse_chan *ch,
+                         struct iovec *iov, int count)
+{
+    struct fuse_out_header *out = iov[0].iov_base;
+
+    out->len = iov_length(iov, count);
+    if (out->unique == 0) {
+        fuse_log(FUSE_LOG_DEBUG, "NOTIFY: code=%d length=%u\n", out->error,
+                 out->len);
+    } else if (out->error) {
+        fuse_log(FUSE_LOG_DEBUG,
+                 "   unique: %llu, error: %i (%s), outsize: %i\n",
+                 (unsigned long long)out->unique, out->error,
+                 strerror(-out->error), out->len);
+    } else {
+        fuse_log(FUSE_LOG_DEBUG, "   unique: %llu, success, outsize: %i\n",
+                 (unsigned long long)out->unique, out->len);
+    }
+
+    if (fuse_lowlevel_is_virtio(se)) {
+        return virtio_send_msg(se, ch, iov, count);
+    }
+
+    abort(); /* virtio should have taken it before here */
+    return 0;
+}
+
+
+int fuse_send_reply_iov_nofree(fuse_req_t req, int error, struct iovec *iov,
+                               int count)
+{
+    struct fuse_out_header out = {
+        .unique = req->unique,
+        .error = error,
+    };
+
+    if (error <= -1000 || error > 0) {
+        fuse_log(FUSE_LOG_ERR, "fuse: bad error value: %i\n", error);
+        error = -ERANGE;
+    }
+
+    iov[0].iov_base = &out;
+    iov[0].iov_len = sizeof(struct fuse_out_header);
+
+    return fuse_send_msg(req->se, req->ch, iov, count);
+}
+
+static int send_reply_iov(fuse_req_t req, int error, struct iovec *iov,
+                          int count)
+{
+    int res;
+
+    res = fuse_send_reply_iov_nofree(req, error, iov, count);
+    fuse_free_req(req);
+    return res;
+}
+
+static int send_reply(fuse_req_t req, int error, const void *arg,
+                      size_t argsize)
+{
+    struct iovec iov[2];
+    int count = 1;
+    if (argsize) {
+        iov[1].iov_base = (void *)arg;
+        iov[1].iov_len = argsize;
+        count++;
+    }
+    return send_reply_iov(req, error, iov, count);
+}
+
+int fuse_reply_iov(fuse_req_t req, const struct iovec *iov, int count)
+{
+    int res;
+    struct iovec *padded_iov;
+
+    padded_iov = malloc((count + 1) * sizeof(struct iovec));
+    if (padded_iov == NULL) {
+        return fuse_reply_err(req, ENOMEM);
+    }
+
+    memcpy(padded_iov + 1, iov, count * sizeof(struct iovec));
+    count++;
+
+    res = send_reply_iov(req, 0, padded_iov, count);
+    free(padded_iov);
+
+    return res;
+}
+
+
+/*
+ * 'buf` is allowed to be empty so that the proper size may be
+ * allocated by the caller
+ */
+size_t fuse_add_direntry(fuse_req_t req, char *buf, size_t bufsize,
+                         const char *name, const struct stat *stbuf, off_t off)
+{
+    (void)req;
+    size_t namelen;
+    size_t entlen;
+    size_t entlen_padded;
+    struct fuse_dirent *dirent;
+
+    namelen = strlen(name);
+    entlen = FUSE_NAME_OFFSET + namelen;
+    entlen_padded = FUSE_DIRENT_ALIGN(entlen);
+
+    if ((buf == NULL) || (entlen_padded > bufsize)) {
+        return entlen_padded;
+    }
+
+    dirent = (struct fuse_dirent *)buf;
+    dirent->ino = stbuf->st_ino;
+    dirent->off = off;
+    dirent->namelen = namelen;
+    dirent->type = (stbuf->st_mode & S_IFMT) >> 12;
+    memcpy(dirent->name, name, namelen);
+    memset(dirent->name + namelen, 0, entlen_padded - entlen);
+
+    return entlen_padded;
+}
+
+static void convert_statfs(const struct statvfs *stbuf,
+                           struct fuse_kstatfs *kstatfs)
+{
+    *kstatfs = (struct fuse_kstatfs){
+        .bsize = stbuf->f_bsize,
+        .frsize = stbuf->f_frsize,
+        .blocks = stbuf->f_blocks,
+        .bfree = stbuf->f_bfree,
+        .bavail = stbuf->f_bavail,
+        .files = stbuf->f_files,
+        .ffree = stbuf->f_ffree,
+        .namelen = stbuf->f_namemax,
+    };
+}
+
+static int send_reply_ok(fuse_req_t req, const void *arg, size_t argsize)
+{
+    return send_reply(req, 0, arg, argsize);
+}
+
+int fuse_reply_err(fuse_req_t req, int err)
+{
+    return send_reply(req, -err, NULL, 0);
+}
+
+void fuse_reply_none(fuse_req_t req)
+{
+    fuse_free_req(req);
+}
+
+static unsigned long calc_timeout_sec(double t)
+{
+    if (t > (double)ULONG_MAX) {
+        return ULONG_MAX;
+    } else if (t < 0.0) {
+        return 0;
+    } else {
+        return (unsigned long)t;
+    }
+}
+
+static unsigned int calc_timeout_nsec(double t)
+{
+    double f = t - (double)calc_timeout_sec(t);
+    if (f < 0.0) {
+        return 0;
+    } else if (f >= 0.999999999) {
+        return 999999999;
+    } else {
+        return (unsigned int)(f * 1.0e9);
+    }
+}
+
+static void fill_entry(struct fuse_entry_out *arg,
+                       const struct fuse_entry_param *e)
+{
+    *arg = (struct fuse_entry_out){
+        .nodeid = e->ino,
+        .generation = e->generation,
+        .entry_valid = calc_timeout_sec(e->entry_timeout),
+        .entry_valid_nsec = calc_timeout_nsec(e->entry_timeout),
+        .attr_valid = calc_timeout_sec(e->attr_timeout),
+        .attr_valid_nsec = calc_timeout_nsec(e->attr_timeout),
+    };
+    convert_stat(&e->attr, &arg->attr);
+}
+
+/*
+ * `buf` is allowed to be empty so that the proper size may be
+ * allocated by the caller
+ */
+size_t fuse_add_direntry_plus(fuse_req_t req, char *buf, size_t bufsize,
+                              const char *name,
+                              const struct fuse_entry_param *e, off_t off)
+{
+    (void)req;
+    size_t namelen;
+    size_t entlen;
+    size_t entlen_padded;
+
+    namelen = strlen(name);
+    entlen = FUSE_NAME_OFFSET_DIRENTPLUS + namelen;
+    entlen_padded = FUSE_DIRENT_ALIGN(entlen);
+    if ((buf == NULL) || (entlen_padded > bufsize)) {
+        return entlen_padded;
+    }
+
+    struct fuse_direntplus *dp = (struct fuse_direntplus *)buf;
+    memset(&dp->entry_out, 0, sizeof(dp->entry_out));
+    fill_entry(&dp->entry_out, e);
+
+    struct fuse_dirent *dirent = &dp->dirent;
+    *dirent = (struct fuse_dirent){
+        .ino = e->attr.st_ino,
+        .off = off,
+        .namelen = namelen,
+        .type = (e->attr.st_mode & S_IFMT) >> 12,
+    };
+    memcpy(dirent->name, name, namelen);
+    memset(dirent->name + namelen, 0, entlen_padded - entlen);
+
+    return entlen_padded;
+}
+
+static void fill_open(struct fuse_open_out *arg, const struct fuse_file_info *f)
+{
+    arg->fh = f->fh;
+    if (f->direct_io) {
+        arg->open_flags |= FOPEN_DIRECT_IO;
+    }
+    if (f->keep_cache) {
+        arg->open_flags |= FOPEN_KEEP_CACHE;
+    }
+    if (f->cache_readdir) {
+        arg->open_flags |= FOPEN_CACHE_DIR;
+    }
+    if (f->nonseekable) {
+        arg->open_flags |= FOPEN_NONSEEKABLE;
+    }
+}
+
+int fuse_reply_entry(fuse_req_t req, const struct fuse_entry_param *e)
+{
+    struct fuse_entry_out arg;
+    size_t size = sizeof(arg);
+
+    memset(&arg, 0, sizeof(arg));
+    fill_entry(&arg, e);
+    return send_reply_ok(req, &arg, size);
+}
+
+int fuse_reply_create(fuse_req_t req, const struct fuse_entry_param *e,
+                      const struct fuse_file_info *f)
+{
+    char buf[sizeof(struct fuse_entry_out) + sizeof(struct fuse_open_out)];
+    size_t entrysize = sizeof(struct fuse_entry_out);
+    struct fuse_entry_out *earg = (struct fuse_entry_out *)buf;
+    struct fuse_open_out *oarg = (struct fuse_open_out *)(buf + entrysize);
+
+    memset(buf, 0, sizeof(buf));
+    fill_entry(earg, e);
+    fill_open(oarg, f);
+    return send_reply_ok(req, buf, entrysize + sizeof(struct fuse_open_out));
+}
+
+int fuse_reply_attr(fuse_req_t req, const struct stat *attr,
+                    double attr_timeout)
+{
+    struct fuse_attr_out arg;
+    size_t size = sizeof(arg);
+
+    memset(&arg, 0, sizeof(arg));
+    arg.attr_valid = calc_timeout_sec(attr_timeout);
+    arg.attr_valid_nsec = calc_timeout_nsec(attr_timeout);
+    convert_stat(attr, &arg.attr);
+
+    return send_reply_ok(req, &arg, size);
+}
+
+int fuse_reply_readlink(fuse_req_t req, const char *linkname)
+{
+    return send_reply_ok(req, linkname, strlen(linkname));
+}
+
+int fuse_reply_open(fuse_req_t req, const struct fuse_file_info *f)
+{
+    struct fuse_open_out arg;
+
+    memset(&arg, 0, sizeof(arg));
+    fill_open(&arg, f);
+    return send_reply_ok(req, &arg, sizeof(arg));
+}
+
+int fuse_reply_write(fuse_req_t req, size_t count)
+{
+    struct fuse_write_out arg;
+
+    memset(&arg, 0, sizeof(arg));
+    arg.size = count;
+
+    return send_reply_ok(req, &arg, sizeof(arg));
+}
+
+int fuse_reply_buf(fuse_req_t req, const char *buf, size_t size)
+{
+    return send_reply_ok(req, buf, size);
+}
+
+static int fuse_send_data_iov_fallback(struct fuse_session *se,
+                                       struct fuse_chan *ch, struct iovec *iov,
+                                       int iov_count, struct fuse_bufvec *buf,
+                                       size_t len)
+{
+    /* Optimize common case */
+    if (buf->count == 1 && buf->idx == 0 && buf->off == 0 &&
+        !(buf->buf[0].flags & FUSE_BUF_IS_FD)) {
+        /*
+         * FIXME: also avoid memory copy if there are multiple buffers
+         * but none of them contain an fd
+         */
+
+        iov[iov_count].iov_base = buf->buf[0].mem;
+        iov[iov_count].iov_len = len;
+        iov_count++;
+        return fuse_send_msg(se, ch, iov, iov_count);
+    }
+
+    if (fuse_lowlevel_is_virtio(se) && buf->count == 1 &&
+        buf->buf[0].flags == (FUSE_BUF_IS_FD | FUSE_BUF_FD_SEEK)) {
+        return virtio_send_data_iov(se, ch, iov, iov_count, buf, len);
+    }
+
+    abort(); /* Will have taken vhost path */
+    return 0;
+}
+
+static int fuse_send_data_iov(struct fuse_session *se, struct fuse_chan *ch,
+                              struct iovec *iov, int iov_count,
+                              struct fuse_bufvec *buf)
+{
+    size_t len = fuse_buf_size(buf);
+
+    return fuse_send_data_iov_fallback(se, ch, iov, iov_count, buf, len);
+}
+
+int fuse_reply_data(fuse_req_t req, struct fuse_bufvec *bufv)
+{
+    struct iovec iov[2];
+    struct fuse_out_header out = {
+        .unique = req->unique,
+    };
+    int res;
+
+    iov[0].iov_base = &out;
+    iov[0].iov_len = sizeof(struct fuse_out_header);
+
+    res = fuse_send_data_iov(req->se, req->ch, iov, 1, bufv);
+    if (res <= 0) {
+        fuse_free_req(req);
+        return res;
+    } else {
+        return fuse_reply_err(req, res);
+    }
+}
+
+int fuse_reply_statfs(fuse_req_t req, const struct statvfs *stbuf)
+{
+    struct fuse_statfs_out arg;
+    size_t size = sizeof(arg);
+
+    memset(&arg, 0, sizeof(arg));
+    convert_statfs(stbuf, &arg.st);
+
+    return send_reply_ok(req, &arg, size);
+}
+
+int fuse_reply_xattr(fuse_req_t req, size_t count)
+{
+    struct fuse_getxattr_out arg;
+
+    memset(&arg, 0, sizeof(arg));
+    arg.size = count;
+
+    return send_reply_ok(req, &arg, sizeof(arg));
+}
+
+int fuse_reply_lock(fuse_req_t req, const struct flock *lock)
+{
+    struct fuse_lk_out arg;
+
+    memset(&arg, 0, sizeof(arg));
+    arg.lk.type = lock->l_type;
+    if (lock->l_type != F_UNLCK) {
+        arg.lk.start = lock->l_start;
+        if (lock->l_len == 0) {
+            arg.lk.end = OFFSET_MAX;
+        } else {
+            arg.lk.end = lock->l_start + lock->l_len - 1;
+        }
+    }
+    arg.lk.pid = lock->l_pid;
+    return send_reply_ok(req, &arg, sizeof(arg));
+}
+
+int fuse_reply_bmap(fuse_req_t req, uint64_t idx)
+{
+    struct fuse_bmap_out arg;
+
+    memset(&arg, 0, sizeof(arg));
+    arg.block = idx;
+
+    return send_reply_ok(req, &arg, sizeof(arg));
+}
+
+static struct fuse_ioctl_iovec *fuse_ioctl_iovec_copy(const struct iovec *iov,
+                                                      size_t count)
+{
+    struct fuse_ioctl_iovec *fiov;
+    size_t i;
+
+    fiov = malloc(sizeof(fiov[0]) * count);
+    if (!fiov) {
+        return NULL;
+    }
+
+    for (i = 0; i < count; i++) {
+        fiov[i].base = (uintptr_t)iov[i].iov_base;
+        fiov[i].len = iov[i].iov_len;
+    }
+
+    return fiov;
+}
+
+int fuse_reply_ioctl_retry(fuse_req_t req, const struct iovec *in_iov,
+                           size_t in_count, const struct iovec *out_iov,
+                           size_t out_count)
+{
+    struct fuse_ioctl_out arg;
+    struct fuse_ioctl_iovec *in_fiov = NULL;
+    struct fuse_ioctl_iovec *out_fiov = NULL;
+    struct iovec iov[4];
+    size_t count = 1;
+    int res;
+
+    memset(&arg, 0, sizeof(arg));
+    arg.flags |= FUSE_IOCTL_RETRY;
+    arg.in_iovs = in_count;
+    arg.out_iovs = out_count;
+    iov[count].iov_base = &arg;
+    iov[count].iov_len = sizeof(arg);
+    count++;
+
+    /* Can't handle non-compat 64bit ioctls on 32bit */
+    if (sizeof(void *) == 4 && req->ioctl_64bit) {
+        res = fuse_reply_err(req, EINVAL);
+        goto out;
+    }
+
+    if (in_count) {
+        in_fiov = fuse_ioctl_iovec_copy(in_iov, in_count);
+        if (!in_fiov) {
+            goto enomem;
+        }
+
+        iov[count].iov_base = (void *)in_fiov;
+        iov[count].iov_len = sizeof(in_fiov[0]) * in_count;
+        count++;
+    }
+    if (out_count) {
+        out_fiov = fuse_ioctl_iovec_copy(out_iov, out_count);
+        if (!out_fiov) {
+            goto enomem;
+        }
+
+        iov[count].iov_base = (void *)out_fiov;
+        iov[count].iov_len = sizeof(out_fiov[0]) * out_count;
+        count++;
+    }
+
+    res = send_reply_iov(req, 0, iov, count);
+out:
+    free(in_fiov);
+    free(out_fiov);
+
+    return res;
+
+enomem:
+    res = fuse_reply_err(req, ENOMEM);
+    goto out;
+}
+
+int fuse_reply_ioctl(fuse_req_t req, int result, const void *buf, size_t size)
+{
+    struct fuse_ioctl_out arg;
+    struct iovec iov[3];
+    size_t count = 1;
+
+    memset(&arg, 0, sizeof(arg));
+    arg.result = result;
+    iov[count].iov_base = &arg;
+    iov[count].iov_len = sizeof(arg);
+    count++;
+
+    if (size) {
+        iov[count].iov_base = (char *)buf;
+        iov[count].iov_len = size;
+        count++;
+    }
+
+    return send_reply_iov(req, 0, iov, count);
+}
+
+int fuse_reply_ioctl_iov(fuse_req_t req, int result, const struct iovec *iov,
+                         int count)
+{
+    struct iovec *padded_iov;
+    struct fuse_ioctl_out arg;
+    int res;
+
+    padded_iov = malloc((count + 2) * sizeof(struct iovec));
+    if (padded_iov == NULL) {
+        return fuse_reply_err(req, ENOMEM);
+    }
+
+    memset(&arg, 0, sizeof(arg));
+    arg.result = result;
+    padded_iov[1].iov_base = &arg;
+    padded_iov[1].iov_len = sizeof(arg);
+
+    memcpy(&padded_iov[2], iov, count * sizeof(struct iovec));
+
+    res = send_reply_iov(req, 0, padded_iov, count + 2);
+    free(padded_iov);
+
+    return res;
+}
+
+int fuse_reply_poll(fuse_req_t req, unsigned revents)
+{
+    struct fuse_poll_out arg;
+
+    memset(&arg, 0, sizeof(arg));
+    arg.revents = revents;
+
+    return send_reply_ok(req, &arg, sizeof(arg));
+}
+
+int fuse_reply_lseek(fuse_req_t req, off_t off)
+{
+    struct fuse_lseek_out arg;
+
+    memset(&arg, 0, sizeof(arg));
+    arg.offset = off;
+
+    return send_reply_ok(req, &arg, sizeof(arg));
+}
+
+static void do_lookup(fuse_req_t req, fuse_ino_t nodeid,
+                      struct fuse_mbuf_iter *iter)
+{
+    const char *name = fuse_mbuf_iter_advance_str(iter);
+    if (!name) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    if (req->se->op.lookup) {
+        req->se->op.lookup(req, nodeid, name);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_forget(fuse_req_t req, fuse_ino_t nodeid,
+                      struct fuse_mbuf_iter *iter)
+{
+    struct fuse_forget_in *arg;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    if (req->se->op.forget) {
+        req->se->op.forget(req, nodeid, arg->nlookup);
+    } else {
+        fuse_reply_none(req);
+    }
+}
+
+static void do_batch_forget(fuse_req_t req, fuse_ino_t nodeid,
+                            struct fuse_mbuf_iter *iter)
+{
+    struct fuse_batch_forget_in *arg;
+    struct fuse_forget_data *forgets;
+    size_t scount;
+
+    (void)nodeid;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_none(req);
+        return;
+    }
+
+    /*
+     * Prevent integer overflow.  The compiler emits the following warning
+     * unless we use the scount local variable:
+     *
+     * error: comparison is always false due to limited range of data type
+     * [-Werror=type-limits]
+     *
+     * This may be true on 64-bit hosts but we need this check for 32-bit
+     * hosts.
+     */
+    scount = arg->count;
+    if (scount > SIZE_MAX / sizeof(forgets[0])) {
+        fuse_reply_none(req);
+        return;
+    }
+
+    forgets = fuse_mbuf_iter_advance(iter, arg->count * sizeof(forgets[0]));
+    if (!forgets) {
+        fuse_reply_none(req);
+        return;
+    }
+
+    if (req->se->op.forget_multi) {
+        req->se->op.forget_multi(req, arg->count, forgets);
+    } else if (req->se->op.forget) {
+        unsigned int i;
+
+        for (i = 0; i < arg->count; i++) {
+            struct fuse_req *dummy_req;
+
+            dummy_req = fuse_ll_alloc_req(req->se);
+            if (dummy_req == NULL) {
+                break;
+            }
+
+            dummy_req->unique = req->unique;
+            dummy_req->ctx = req->ctx;
+            dummy_req->ch = NULL;
+
+            req->se->op.forget(dummy_req, forgets[i].ino, forgets[i].nlookup);
+        }
+        fuse_reply_none(req);
+    } else {
+        fuse_reply_none(req);
+    }
+}
+
+static void do_getattr(fuse_req_t req, fuse_ino_t nodeid,
+                       struct fuse_mbuf_iter *iter)
+{
+    struct fuse_file_info *fip = NULL;
+    struct fuse_file_info fi;
+
+    struct fuse_getattr_in *arg;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    if (arg->getattr_flags & FUSE_GETATTR_FH) {
+        memset(&fi, 0, sizeof(fi));
+        fi.fh = arg->fh;
+        fip = &fi;
+    }
+
+    if (req->se->op.getattr) {
+        req->se->op.getattr(req, nodeid, fip);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_setattr(fuse_req_t req, fuse_ino_t nodeid,
+                       struct fuse_mbuf_iter *iter)
+{
+    if (req->se->op.setattr) {
+        struct fuse_setattr_in *arg;
+        struct fuse_file_info *fi = NULL;
+        struct fuse_file_info fi_store;
+        struct stat stbuf;
+
+        arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+        if (!arg) {
+            fuse_reply_err(req, EINVAL);
+            return;
+        }
+
+        memset(&stbuf, 0, sizeof(stbuf));
+        convert_attr(arg, &stbuf);
+        if (arg->valid & FATTR_FH) {
+            arg->valid &= ~FATTR_FH;
+            memset(&fi_store, 0, sizeof(fi_store));
+            fi = &fi_store;
+            fi->fh = arg->fh;
+        }
+        arg->valid &= FUSE_SET_ATTR_MODE | FUSE_SET_ATTR_UID |
+                      FUSE_SET_ATTR_GID | FUSE_SET_ATTR_SIZE |
+                      FUSE_SET_ATTR_ATIME | FUSE_SET_ATTR_MTIME |
+                      FUSE_SET_ATTR_ATIME_NOW | FUSE_SET_ATTR_MTIME_NOW |
+                      FUSE_SET_ATTR_CTIME;
+
+        req->se->op.setattr(req, nodeid, &stbuf, arg->valid, fi);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_access(fuse_req_t req, fuse_ino_t nodeid,
+                      struct fuse_mbuf_iter *iter)
+{
+    struct fuse_access_in *arg;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    if (req->se->op.access) {
+        req->se->op.access(req, nodeid, arg->mask);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_readlink(fuse_req_t req, fuse_ino_t nodeid,
+                        struct fuse_mbuf_iter *iter)
+{
+    (void)iter;
+
+    if (req->se->op.readlink) {
+        req->se->op.readlink(req, nodeid);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_mknod(fuse_req_t req, fuse_ino_t nodeid,
+                     struct fuse_mbuf_iter *iter)
+{
+    struct fuse_mknod_in *arg;
+    const char *name;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    name = fuse_mbuf_iter_advance_str(iter);
+    if (!arg || !name) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    req->ctx.umask = arg->umask;
+
+    if (req->se->op.mknod) {
+        req->se->op.mknod(req, nodeid, name, arg->mode, arg->rdev);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_mkdir(fuse_req_t req, fuse_ino_t nodeid,
+                     struct fuse_mbuf_iter *iter)
+{
+    struct fuse_mkdir_in *arg;
+    const char *name;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    name = fuse_mbuf_iter_advance_str(iter);
+    if (!arg || !name) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    req->ctx.umask = arg->umask;
+
+    if (req->se->op.mkdir) {
+        req->se->op.mkdir(req, nodeid, name, arg->mode);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_unlink(fuse_req_t req, fuse_ino_t nodeid,
+                      struct fuse_mbuf_iter *iter)
+{
+    const char *name = fuse_mbuf_iter_advance_str(iter);
+
+    if (!name) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    if (req->se->op.unlink) {
+        req->se->op.unlink(req, nodeid, name);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_rmdir(fuse_req_t req, fuse_ino_t nodeid,
+                     struct fuse_mbuf_iter *iter)
+{
+    const char *name = fuse_mbuf_iter_advance_str(iter);
+
+    if (!name) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    if (req->se->op.rmdir) {
+        req->se->op.rmdir(req, nodeid, name);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_symlink(fuse_req_t req, fuse_ino_t nodeid,
+                       struct fuse_mbuf_iter *iter)
+{
+    const char *name = fuse_mbuf_iter_advance_str(iter);
+    const char *linkname = fuse_mbuf_iter_advance_str(iter);
+
+    if (!name || !linkname) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    if (req->se->op.symlink) {
+        req->se->op.symlink(req, linkname, nodeid, name);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_rename(fuse_req_t req, fuse_ino_t nodeid,
+                      struct fuse_mbuf_iter *iter)
+{
+    struct fuse_rename_in *arg;
+    const char *oldname;
+    const char *newname;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    oldname = fuse_mbuf_iter_advance_str(iter);
+    newname = fuse_mbuf_iter_advance_str(iter);
+    if (!arg || !oldname || !newname) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    if (req->se->op.rename) {
+        req->se->op.rename(req, nodeid, oldname, arg->newdir, newname, 0);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_rename2(fuse_req_t req, fuse_ino_t nodeid,
+                       struct fuse_mbuf_iter *iter)
+{
+    struct fuse_rename2_in *arg;
+    const char *oldname;
+    const char *newname;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    oldname = fuse_mbuf_iter_advance_str(iter);
+    newname = fuse_mbuf_iter_advance_str(iter);
+    if (!arg || !oldname || !newname) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    if (req->se->op.rename) {
+        req->se->op.rename(req, nodeid, oldname, arg->newdir, newname,
+                           arg->flags);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_link(fuse_req_t req, fuse_ino_t nodeid,
+                    struct fuse_mbuf_iter *iter)
+{
+    struct fuse_link_in *arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    const char *name = fuse_mbuf_iter_advance_str(iter);
+
+    if (!arg || !name) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    if (req->se->op.link) {
+        req->se->op.link(req, arg->oldnodeid, nodeid, name);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_create(fuse_req_t req, fuse_ino_t nodeid,
+                      struct fuse_mbuf_iter *iter)
+{
+    if (req->se->op.create) {
+        struct fuse_create_in *arg;
+        struct fuse_file_info fi;
+        const char *name;
+
+        arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+        name = fuse_mbuf_iter_advance_str(iter);
+        if (!arg || !name) {
+            fuse_reply_err(req, EINVAL);
+            return;
+        }
+
+        memset(&fi, 0, sizeof(fi));
+        fi.flags = arg->flags;
+
+        req->ctx.umask = arg->umask;
+
+        req->se->op.create(req, nodeid, name, arg->mode, &fi);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_open(fuse_req_t req, fuse_ino_t nodeid,
+                    struct fuse_mbuf_iter *iter)
+{
+    struct fuse_open_in *arg;
+    struct fuse_file_info fi;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    memset(&fi, 0, sizeof(fi));
+    fi.flags = arg->flags;
+
+    if (req->se->op.open) {
+        req->se->op.open(req, nodeid, &fi);
+    } else {
+        fuse_reply_open(req, &fi);
+    }
+}
+
+static void do_read(fuse_req_t req, fuse_ino_t nodeid,
+                    struct fuse_mbuf_iter *iter)
+{
+    if (req->se->op.read) {
+        struct fuse_read_in *arg;
+        struct fuse_file_info fi;
+
+        arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+
+        memset(&fi, 0, sizeof(fi));
+        fi.fh = arg->fh;
+        fi.lock_owner = arg->lock_owner;
+        fi.flags = arg->flags;
+        req->se->op.read(req, nodeid, arg->size, arg->offset, &fi);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_write(fuse_req_t req, fuse_ino_t nodeid,
+                     struct fuse_mbuf_iter *iter)
+{
+    struct fuse_write_in *arg;
+    struct fuse_file_info fi;
+    const char *param;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    param = fuse_mbuf_iter_advance(iter, arg->size);
+    if (!param) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    memset(&fi, 0, sizeof(fi));
+    fi.fh = arg->fh;
+    fi.writepage = (arg->write_flags & FUSE_WRITE_CACHE) != 0;
+    fi.kill_priv = !!(arg->write_flags & FUSE_WRITE_KILL_PRIV);
+
+    fi.lock_owner = arg->lock_owner;
+    fi.flags = arg->flags;
+
+    if (req->se->op.write) {
+        req->se->op.write(req, nodeid, param, arg->size, arg->offset, &fi);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_write_buf(fuse_req_t req, fuse_ino_t nodeid,
+                         struct fuse_mbuf_iter *iter, struct fuse_bufvec *ibufv)
+{
+    struct fuse_session *se = req->se;
+    struct fuse_bufvec *pbufv = ibufv;
+    struct fuse_bufvec tmpbufv = {
+        .buf[0] = ibufv->buf[0],
+        .count = 1,
+    };
+    struct fuse_write_in *arg;
+    size_t arg_size = sizeof(*arg);
+    struct fuse_file_info fi;
+
+    memset(&fi, 0, sizeof(fi));
+
+    arg = fuse_mbuf_iter_advance(iter, arg_size);
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    fi.lock_owner = arg->lock_owner;
+    fi.flags = arg->flags;
+    fi.fh = arg->fh;
+    fi.writepage = !!(arg->write_flags & FUSE_WRITE_CACHE);
+    fi.kill_priv = !!(arg->write_flags & FUSE_WRITE_KILL_PRIV);
+
+    if (ibufv->count == 1) {
+        assert(!(tmpbufv.buf[0].flags & FUSE_BUF_IS_FD));
+        tmpbufv.buf[0].mem = ((char *)arg) + arg_size;
+        tmpbufv.buf[0].size -= sizeof(struct fuse_in_header) + arg_size;
+        pbufv = &tmpbufv;
+    } else {
+        /*
+         *  Input bufv contains the headers in the first element
+         * and the data in the rest, we need to skip that first element
+         */
+        ibufv->buf[0].size = 0;
+    }
+
+    if (fuse_buf_size(pbufv) != arg->size) {
+        fuse_log(FUSE_LOG_ERR,
+                 "fuse: do_write_buf: buffer size doesn't match arg->size\n");
+        fuse_reply_err(req, EIO);
+        return;
+    }
+
+    se->op.write_buf(req, nodeid, pbufv, arg->offset, &fi);
+}
+
+static void do_flush(fuse_req_t req, fuse_ino_t nodeid,
+                     struct fuse_mbuf_iter *iter)
+{
+    struct fuse_flush_in *arg;
+    struct fuse_file_info fi;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    memset(&fi, 0, sizeof(fi));
+    fi.fh = arg->fh;
+    fi.flush = 1;
+    fi.lock_owner = arg->lock_owner;
+
+    if (req->se->op.flush) {
+        req->se->op.flush(req, nodeid, &fi);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_release(fuse_req_t req, fuse_ino_t nodeid,
+                       struct fuse_mbuf_iter *iter)
+{
+    struct fuse_release_in *arg;
+    struct fuse_file_info fi;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    memset(&fi, 0, sizeof(fi));
+    fi.flags = arg->flags;
+    fi.fh = arg->fh;
+    fi.flush = (arg->release_flags & FUSE_RELEASE_FLUSH) ? 1 : 0;
+    fi.lock_owner = arg->lock_owner;
+
+    if (arg->release_flags & FUSE_RELEASE_FLOCK_UNLOCK) {
+        fi.flock_release = 1;
+    }
+
+    if (req->se->op.release) {
+        req->se->op.release(req, nodeid, &fi);
+    } else {
+        fuse_reply_err(req, 0);
+    }
+}
+
+static void do_fsync(fuse_req_t req, fuse_ino_t nodeid,
+                     struct fuse_mbuf_iter *iter)
+{
+    struct fuse_fsync_in *arg;
+    struct fuse_file_info fi;
+    int datasync;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+    datasync = arg->fsync_flags & 1;
+
+    memset(&fi, 0, sizeof(fi));
+    fi.fh = arg->fh;
+
+    if (req->se->op.fsync) {
+        if (fi.fh == (uint64_t)-1) {
+            req->se->op.fsync(req, nodeid, datasync, NULL);
+        } else {
+            req->se->op.fsync(req, nodeid, datasync, &fi);
+        }
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_opendir(fuse_req_t req, fuse_ino_t nodeid,
+                       struct fuse_mbuf_iter *iter)
+{
+    struct fuse_open_in *arg;
+    struct fuse_file_info fi;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    memset(&fi, 0, sizeof(fi));
+    fi.flags = arg->flags;
+
+    if (req->se->op.opendir) {
+        req->se->op.opendir(req, nodeid, &fi);
+    } else {
+        fuse_reply_open(req, &fi);
+    }
+}
+
+static void do_readdir(fuse_req_t req, fuse_ino_t nodeid,
+                       struct fuse_mbuf_iter *iter)
+{
+    struct fuse_read_in *arg;
+    struct fuse_file_info fi;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    memset(&fi, 0, sizeof(fi));
+    fi.fh = arg->fh;
+
+    if (req->se->op.readdir) {
+        req->se->op.readdir(req, nodeid, arg->size, arg->offset, &fi);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_readdirplus(fuse_req_t req, fuse_ino_t nodeid,
+                           struct fuse_mbuf_iter *iter)
+{
+    struct fuse_read_in *arg;
+    struct fuse_file_info fi;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    memset(&fi, 0, sizeof(fi));
+    fi.fh = arg->fh;
+
+    if (req->se->op.readdirplus) {
+        req->se->op.readdirplus(req, nodeid, arg->size, arg->offset, &fi);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_releasedir(fuse_req_t req, fuse_ino_t nodeid,
+                          struct fuse_mbuf_iter *iter)
+{
+    struct fuse_release_in *arg;
+    struct fuse_file_info fi;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    memset(&fi, 0, sizeof(fi));
+    fi.flags = arg->flags;
+    fi.fh = arg->fh;
+
+    if (req->se->op.releasedir) {
+        req->se->op.releasedir(req, nodeid, &fi);
+    } else {
+        fuse_reply_err(req, 0);
+    }
+}
+
+static void do_fsyncdir(fuse_req_t req, fuse_ino_t nodeid,
+                        struct fuse_mbuf_iter *iter)
+{
+    struct fuse_fsync_in *arg;
+    struct fuse_file_info fi;
+    int datasync;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+    datasync = arg->fsync_flags & 1;
+
+    memset(&fi, 0, sizeof(fi));
+    fi.fh = arg->fh;
+
+    if (req->se->op.fsyncdir) {
+        req->se->op.fsyncdir(req, nodeid, datasync, &fi);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_statfs(fuse_req_t req, fuse_ino_t nodeid,
+                      struct fuse_mbuf_iter *iter)
+{
+    (void)nodeid;
+    (void)iter;
+
+    if (req->se->op.statfs) {
+        req->se->op.statfs(req, nodeid);
+    } else {
+        struct statvfs buf = {
+            .f_namemax = 255,
+            .f_bsize = 512,
+        };
+        fuse_reply_statfs(req, &buf);
+    }
+}
+
+static void do_setxattr(fuse_req_t req, fuse_ino_t nodeid,
+                        struct fuse_mbuf_iter *iter)
+{
+    struct fuse_setxattr_in *arg;
+    const char *name;
+    const char *value;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    name = fuse_mbuf_iter_advance_str(iter);
+    if (!arg || !name) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    value = fuse_mbuf_iter_advance(iter, arg->size);
+    if (!value) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    if (req->se->op.setxattr) {
+        req->se->op.setxattr(req, nodeid, name, value, arg->size, arg->flags);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_getxattr(fuse_req_t req, fuse_ino_t nodeid,
+                        struct fuse_mbuf_iter *iter)
+{
+    struct fuse_getxattr_in *arg;
+    const char *name;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    name = fuse_mbuf_iter_advance_str(iter);
+    if (!arg || !name) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    if (req->se->op.getxattr) {
+        req->se->op.getxattr(req, nodeid, name, arg->size);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_listxattr(fuse_req_t req, fuse_ino_t nodeid,
+                         struct fuse_mbuf_iter *iter)
+{
+    struct fuse_getxattr_in *arg;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    if (req->se->op.listxattr) {
+        req->se->op.listxattr(req, nodeid, arg->size);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_removexattr(fuse_req_t req, fuse_ino_t nodeid,
+                           struct fuse_mbuf_iter *iter)
+{
+    const char *name = fuse_mbuf_iter_advance_str(iter);
+
+    if (!name) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    if (req->se->op.removexattr) {
+        req->se->op.removexattr(req, nodeid, name);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void convert_fuse_file_lock(struct fuse_file_lock *fl,
+                                   struct flock *flock)
+{
+    memset(flock, 0, sizeof(struct flock));
+    flock->l_type = fl->type;
+    flock->l_whence = SEEK_SET;
+    flock->l_start = fl->start;
+    if (fl->end == OFFSET_MAX) {
+        flock->l_len = 0;
+    } else {
+        flock->l_len = fl->end - fl->start + 1;
+    }
+    flock->l_pid = fl->pid;
+}
+
+static void do_getlk(fuse_req_t req, fuse_ino_t nodeid,
+                     struct fuse_mbuf_iter *iter)
+{
+    struct fuse_lk_in *arg;
+    struct fuse_file_info fi;
+    struct flock flock;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    memset(&fi, 0, sizeof(fi));
+    fi.fh = arg->fh;
+    fi.lock_owner = arg->owner;
+
+    convert_fuse_file_lock(&arg->lk, &flock);
+    if (req->se->op.getlk) {
+        req->se->op.getlk(req, nodeid, &fi, &flock);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_setlk_common(fuse_req_t req, fuse_ino_t nodeid,
+                            struct fuse_mbuf_iter *iter, int sleep)
+{
+    struct fuse_lk_in *arg;
+    struct fuse_file_info fi;
+    struct flock flock;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    memset(&fi, 0, sizeof(fi));
+    fi.fh = arg->fh;
+    fi.lock_owner = arg->owner;
+
+    if (arg->lk_flags & FUSE_LK_FLOCK) {
+        int op = 0;
+
+        switch (arg->lk.type) {
+        case F_RDLCK:
+            op = LOCK_SH;
+            break;
+        case F_WRLCK:
+            op = LOCK_EX;
+            break;
+        case F_UNLCK:
+            op = LOCK_UN;
+            break;
+        }
+        if (!sleep) {
+            op |= LOCK_NB;
+        }
+
+        if (req->se->op.flock) {
+            req->se->op.flock(req, nodeid, &fi, op);
+        } else {
+            fuse_reply_err(req, ENOSYS);
+        }
+    } else {
+        convert_fuse_file_lock(&arg->lk, &flock);
+        if (req->se->op.setlk) {
+            req->se->op.setlk(req, nodeid, &fi, &flock, sleep);
+        } else {
+            fuse_reply_err(req, ENOSYS);
+        }
+    }
+}
+
+static void do_setlk(fuse_req_t req, fuse_ino_t nodeid,
+                     struct fuse_mbuf_iter *iter)
+{
+    do_setlk_common(req, nodeid, iter, 0);
+}
+
+static void do_setlkw(fuse_req_t req, fuse_ino_t nodeid,
+                      struct fuse_mbuf_iter *iter)
+{
+    do_setlk_common(req, nodeid, iter, 1);
+}
+
+static int find_interrupted(struct fuse_session *se, struct fuse_req *req)
+{
+    struct fuse_req *curr;
+
+    for (curr = se->list.next; curr != &se->list; curr = curr->next) {
+        if (curr->unique == req->u.i.unique) {
+            fuse_interrupt_func_t func;
+            void *data;
+
+            curr->ctr++;
+            pthread_mutex_unlock(&se->lock);
+
+            /* Ugh, ugly locking */
+            pthread_mutex_lock(&curr->lock);
+            pthread_mutex_lock(&se->lock);
+            curr->interrupted = 1;
+            func = curr->u.ni.func;
+            data = curr->u.ni.data;
+            pthread_mutex_unlock(&se->lock);
+            if (func) {
+                func(curr, data);
+            }
+            pthread_mutex_unlock(&curr->lock);
+
+            pthread_mutex_lock(&se->lock);
+            curr->ctr--;
+            if (!curr->ctr) {
+                destroy_req(curr);
+            }
+
+            return 1;
+        }
+    }
+    for (curr = se->interrupts.next; curr != &se->interrupts;
+         curr = curr->next) {
+        if (curr->u.i.unique == req->u.i.unique) {
+            return 1;
+        }
+    }
+    return 0;
+}
+
+static void do_interrupt(fuse_req_t req, fuse_ino_t nodeid,
+                         struct fuse_mbuf_iter *iter)
+{
+    struct fuse_interrupt_in *arg;
+    struct fuse_session *se = req->se;
+
+    (void)nodeid;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    fuse_log(FUSE_LOG_DEBUG, "INTERRUPT: %llu\n",
+             (unsigned long long)arg->unique);
+
+    req->u.i.unique = arg->unique;
+
+    pthread_mutex_lock(&se->lock);
+    if (find_interrupted(se, req)) {
+        destroy_req(req);
+    } else {
+        list_add_req(req, &se->interrupts);
+    }
+    pthread_mutex_unlock(&se->lock);
+}
+
+static struct fuse_req *check_interrupt(struct fuse_session *se,
+                                        struct fuse_req *req)
+{
+    struct fuse_req *curr;
+
+    for (curr = se->interrupts.next; curr != &se->interrupts;
+         curr = curr->next) {
+        if (curr->u.i.unique == req->unique) {
+            req->interrupted = 1;
+            list_del_req(curr);
+            free(curr);
+            return NULL;
+        }
+    }
+    curr = se->interrupts.next;
+    if (curr != &se->interrupts) {
+        list_del_req(curr);
+        list_init_req(curr);
+        return curr;
+    } else {
+        return NULL;
+    }
+}
+
+static void do_bmap(fuse_req_t req, fuse_ino_t nodeid,
+                    struct fuse_mbuf_iter *iter)
+{
+    struct fuse_bmap_in *arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    if (req->se->op.bmap) {
+        req->se->op.bmap(req, nodeid, arg->blocksize, arg->block);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_ioctl(fuse_req_t req, fuse_ino_t nodeid,
+                     struct fuse_mbuf_iter *iter)
+{
+    struct fuse_ioctl_in *arg;
+    unsigned int flags;
+    void *in_buf = NULL;
+    struct fuse_file_info fi;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    flags = arg->flags;
+    if (flags & FUSE_IOCTL_DIR && !(req->se->conn.want & FUSE_CAP_IOCTL_DIR)) {
+        fuse_reply_err(req, ENOTTY);
+        return;
+    }
+
+    if (arg->in_size) {
+        in_buf = fuse_mbuf_iter_advance(iter, arg->in_size);
+        if (!in_buf) {
+            fuse_reply_err(req, EINVAL);
+            return;
+        }
+    }
+
+    memset(&fi, 0, sizeof(fi));
+    fi.fh = arg->fh;
+
+    if (sizeof(void *) == 4 && !(flags & FUSE_IOCTL_32BIT)) {
+        req->ioctl_64bit = 1;
+    }
+
+    if (req->se->op.ioctl) {
+        req->se->op.ioctl(req, nodeid, arg->cmd, (void *)(uintptr_t)arg->arg,
+                          &fi, flags, in_buf, arg->in_size, arg->out_size);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+void fuse_pollhandle_destroy(struct fuse_pollhandle *ph)
+{
+    free(ph);
+}
+
+static void do_poll(fuse_req_t req, fuse_ino_t nodeid,
+                    struct fuse_mbuf_iter *iter)
+{
+    struct fuse_poll_in *arg;
+    struct fuse_file_info fi;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    memset(&fi, 0, sizeof(fi));
+    fi.fh = arg->fh;
+    fi.poll_events = arg->events;
+
+    if (req->se->op.poll) {
+        struct fuse_pollhandle *ph = NULL;
+
+        if (arg->flags & FUSE_POLL_SCHEDULE_NOTIFY) {
+            ph = malloc(sizeof(struct fuse_pollhandle));
+            if (ph == NULL) {
+                fuse_reply_err(req, ENOMEM);
+                return;
+            }
+            ph->kh = arg->kh;
+            ph->se = req->se;
+        }
+
+        req->se->op.poll(req, nodeid, &fi, ph);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_fallocate(fuse_req_t req, fuse_ino_t nodeid,
+                         struct fuse_mbuf_iter *iter)
+{
+    struct fuse_fallocate_in *arg;
+    struct fuse_file_info fi;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    memset(&fi, 0, sizeof(fi));
+    fi.fh = arg->fh;
+
+    if (req->se->op.fallocate) {
+        req->se->op.fallocate(req, nodeid, arg->mode, arg->offset, arg->length,
+                              &fi);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_copy_file_range(fuse_req_t req, fuse_ino_t nodeid_in,
+                               struct fuse_mbuf_iter *iter)
+{
+    struct fuse_copy_file_range_in *arg;
+    struct fuse_file_info fi_in, fi_out;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    memset(&fi_in, 0, sizeof(fi_in));
+    fi_in.fh = arg->fh_in;
+
+    memset(&fi_out, 0, sizeof(fi_out));
+    fi_out.fh = arg->fh_out;
+
+
+    if (req->se->op.copy_file_range) {
+        req->se->op.copy_file_range(req, nodeid_in, arg->off_in, &fi_in,
+                                    arg->nodeid_out, arg->off_out, &fi_out,
+                                    arg->len, arg->flags);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_lseek(fuse_req_t req, fuse_ino_t nodeid,
+                     struct fuse_mbuf_iter *iter)
+{
+    struct fuse_lseek_in *arg;
+    struct fuse_file_info fi;
+
+    arg = fuse_mbuf_iter_advance(iter, sizeof(*arg));
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+    memset(&fi, 0, sizeof(fi));
+    fi.fh = arg->fh;
+
+    if (req->se->op.lseek) {
+        req->se->op.lseek(req, nodeid, arg->offset, arg->whence, &fi);
+    } else {
+        fuse_reply_err(req, ENOSYS);
+    }
+}
+
+static void do_init(fuse_req_t req, fuse_ino_t nodeid,
+                    struct fuse_mbuf_iter *iter)
+{
+    size_t compat_size = offsetof(struct fuse_init_in, max_readahead);
+    struct fuse_init_in *arg;
+    struct fuse_init_out outarg;
+    struct fuse_session *se = req->se;
+    size_t bufsize = se->bufsize;
+    size_t outargsize = sizeof(outarg);
+
+    (void)nodeid;
+
+    /* First consume the old fields... */
+    arg = fuse_mbuf_iter_advance(iter, compat_size);
+    if (!arg) {
+        fuse_reply_err(req, EINVAL);
+        return;
+    }
+
+    /* ...and now consume the new fields. */
+    if (arg->major == 7 && arg->minor >= 6) {
+        if (!fuse_mbuf_iter_advance(iter, sizeof(*arg) - compat_size)) {
+            fuse_reply_err(req, EINVAL);
+            return;
+        }
+    }
+
+    fuse_log(FUSE_LOG_DEBUG, "INIT: %u.%u\n", arg->major, arg->minor);
+    if (arg->major == 7 && arg->minor >= 6) {
+        fuse_log(FUSE_LOG_DEBUG, "flags=0x%08x\n", arg->flags);
+        fuse_log(FUSE_LOG_DEBUG, "max_readahead=0x%08x\n", arg->max_readahead);
+    }
+    se->conn.proto_major = arg->major;
+    se->conn.proto_minor = arg->minor;
+    se->conn.capable = 0;
+    se->conn.want = 0;
+
+    memset(&outarg, 0, sizeof(outarg));
+    outarg.major = FUSE_KERNEL_VERSION;
+    outarg.minor = FUSE_KERNEL_MINOR_VERSION;
+
+    if (arg->major < 7 || (arg->major == 7 && arg->minor < 31)) {
+        fuse_log(FUSE_LOG_ERR, "fuse: unsupported protocol version: %u.%u\n",
+                 arg->major, arg->minor);
+        fuse_reply_err(req, EPROTO);
+        return;
+    }
+
+    if (arg->major > 7) {
+        /* Wait for a second INIT request with a 7.X version */
+        send_reply_ok(req, &outarg, sizeof(outarg));
+        return;
+    }
+
+    if (arg->max_readahead < se->conn.max_readahead) {
+        se->conn.max_readahead = arg->max_readahead;
+    }
+    if (arg->flags & FUSE_ASYNC_READ) {
+        se->conn.capable |= FUSE_CAP_ASYNC_READ;
+    }
+    if (arg->flags & FUSE_POSIX_LOCKS) {
+        se->conn.capable |= FUSE_CAP_POSIX_LOCKS;
+    }
+    if (arg->flags & FUSE_ATOMIC_O_TRUNC) {
+        se->conn.capable |= FUSE_CAP_ATOMIC_O_TRUNC;
+    }
+    if (arg->flags & FUSE_EXPORT_SUPPORT) {
+        se->conn.capable |= FUSE_CAP_EXPORT_SUPPORT;
+    }
+    if (arg->flags & FUSE_DONT_MASK) {
+        se->conn.capable |= FUSE_CAP_DONT_MASK;
+    }
+    if (arg->flags & FUSE_FLOCK_LOCKS) {
+        se->conn.capable |= FUSE_CAP_FLOCK_LOCKS;
+    }
+    if (arg->flags & FUSE_AUTO_INVAL_DATA) {
+        se->conn.capable |= FUSE_CAP_AUTO_INVAL_DATA;
+    }
+    if (arg->flags & FUSE_DO_READDIRPLUS) {
+        se->conn.capable |= FUSE_CAP_READDIRPLUS;
+    }
+    if (arg->flags & FUSE_READDIRPLUS_AUTO) {
+        se->conn.capable |= FUSE_CAP_READDIRPLUS_AUTO;
+    }
+    if (arg->flags & FUSE_ASYNC_DIO) {
+        se->conn.capable |= FUSE_CAP_ASYNC_DIO;
+    }
+    if (arg->flags & FUSE_WRITEBACK_CACHE) {
+        se->conn.capable |= FUSE_CAP_WRITEBACK_CACHE;
+    }
+    if (arg->flags & FUSE_NO_OPEN_SUPPORT) {
+        se->conn.capable |= FUSE_CAP_NO_OPEN_SUPPORT;
+    }
+    if (arg->flags & FUSE_PARALLEL_DIROPS) {
+        se->conn.capable |= FUSE_CAP_PARALLEL_DIROPS;
+    }
+    if (arg->flags & FUSE_POSIX_ACL) {
+        se->conn.capable |= FUSE_CAP_POSIX_ACL;
+    }
+    if (arg->flags & FUSE_HANDLE_KILLPRIV) {
+        se->conn.capable |= FUSE_CAP_HANDLE_KILLPRIV;
+    }
+    if (arg->flags & FUSE_NO_OPENDIR_SUPPORT) {
+        se->conn.capable |= FUSE_CAP_NO_OPENDIR_SUPPORT;
+    }
+    if (!(arg->flags & FUSE_MAX_PAGES)) {
+        size_t max_bufsize = FUSE_DEFAULT_MAX_PAGES_PER_REQ * getpagesize() +
+                             FUSE_BUFFER_HEADER_SIZE;
+        if (bufsize > max_bufsize) {
+            bufsize = max_bufsize;
+        }
+    }
+#ifdef HAVE_SPLICE
+#ifdef HAVE_VMSPLICE
+    se->conn.capable |= FUSE_CAP_SPLICE_WRITE | FUSE_CAP_SPLICE_MOVE;
+#endif
+    se->conn.capable |= FUSE_CAP_SPLICE_READ;
+#endif
+    se->conn.capable |= FUSE_CAP_IOCTL_DIR;
+
+    /*
+     * Default settings for modern filesystems.
+     *
+     * Most of these capabilities were disabled by default in
+     * libfuse2 for backwards compatibility reasons. In libfuse3,
+     * we can finally enable them by default (as long as they're
+     * supported by the kernel).
+     */
+#define LL_SET_DEFAULT(cond, cap)             \
+    if ((cond) && (se->conn.capable & (cap))) \
+        se->conn.want |= (cap)
+    LL_SET_DEFAULT(1, FUSE_CAP_ASYNC_READ);
+    LL_SET_DEFAULT(1, FUSE_CAP_PARALLEL_DIROPS);
+    LL_SET_DEFAULT(1, FUSE_CAP_AUTO_INVAL_DATA);
+    LL_SET_DEFAULT(1, FUSE_CAP_HANDLE_KILLPRIV);
+    LL_SET_DEFAULT(1, FUSE_CAP_ASYNC_DIO);
+    LL_SET_DEFAULT(1, FUSE_CAP_IOCTL_DIR);
+    LL_SET_DEFAULT(1, FUSE_CAP_ATOMIC_O_TRUNC);
+    LL_SET_DEFAULT(se->op.write_buf, FUSE_CAP_SPLICE_READ);
+    LL_SET_DEFAULT(se->op.getlk && se->op.setlk, FUSE_CAP_POSIX_LOCKS);
+    LL_SET_DEFAULT(se->op.flock, FUSE_CAP_FLOCK_LOCKS);
+    LL_SET_DEFAULT(se->op.readdirplus, FUSE_CAP_READDIRPLUS);
+    LL_SET_DEFAULT(se->op.readdirplus && se->op.readdir,
+                   FUSE_CAP_READDIRPLUS_AUTO);
+    se->conn.time_gran = 1;
+
+    if (bufsize < FUSE_MIN_READ_BUFFER) {
+        fuse_log(FUSE_LOG_ERR, "fuse: warning: buffer size too small: %zu\n",
+                 bufsize);
+        bufsize = FUSE_MIN_READ_BUFFER;
+    }
+    se->bufsize = bufsize;
+
+    if (se->conn.max_write > bufsize - FUSE_BUFFER_HEADER_SIZE) {
+        se->conn.max_write = bufsize - FUSE_BUFFER_HEADER_SIZE;
+    }
+
+    se->got_init = 1;
+    se->got_destroy = 0;
+    if (se->op.init) {
+        se->op.init(se->userdata, &se->conn);
+    }
+
+    if (se->conn.want & (~se->conn.capable)) {
+        fuse_log(FUSE_LOG_ERR,
+                 "fuse: error: filesystem requested capabilities "
+                 "0x%x that are not supported by kernel, aborting.\n",
+                 se->conn.want & (~se->conn.capable));
+        fuse_reply_err(req, EPROTO);
+        se->error = -EPROTO;
+        fuse_session_exit(se);
+        return;
+    }
+
+    if (se->conn.max_write < bufsize - FUSE_BUFFER_HEADER_SIZE) {
+        se->bufsize = se->conn.max_write + FUSE_BUFFER_HEADER_SIZE;
+    }
+    if (arg->flags & FUSE_MAX_PAGES) {
+        outarg.flags |= FUSE_MAX_PAGES;
+        outarg.max_pages = (se->conn.max_write - 1) / getpagesize() + 1;
+    }
+
+    /*
+     * Always enable big writes, this is superseded
+     * by the max_write option
+     */
+    outarg.flags |= FUSE_BIG_WRITES;
+
+    if (se->conn.want & FUSE_CAP_ASYNC_READ) {
+        outarg.flags |= FUSE_ASYNC_READ;
+    }
+    if (se->conn.want & FUSE_CAP_PARALLEL_DIROPS) {
+        outarg.flags |= FUSE_PARALLEL_DIROPS;
+    }
+    if (se->conn.want & FUSE_CAP_POSIX_LOCKS) {
+        outarg.flags |= FUSE_POSIX_LOCKS;
+    }
+    if (se->conn.want & FUSE_CAP_ATOMIC_O_TRUNC) {
+        outarg.flags |= FUSE_ATOMIC_O_TRUNC;
+    }
+    if (se->conn.want & FUSE_CAP_EXPORT_SUPPORT) {
+        outarg.flags |= FUSE_EXPORT_SUPPORT;
+    }
+    if (se->conn.want & FUSE_CAP_DONT_MASK) {
+        outarg.flags |= FUSE_DONT_MASK;
+    }
+    if (se->conn.want & FUSE_CAP_FLOCK_LOCKS) {
+        outarg.flags |= FUSE_FLOCK_LOCKS;
+    }
+    if (se->conn.want & FUSE_CAP_AUTO_INVAL_DATA) {
+        outarg.flags |= FUSE_AUTO_INVAL_DATA;
+    }
+    if (se->conn.want & FUSE_CAP_READDIRPLUS) {
+        outarg.flags |= FUSE_DO_READDIRPLUS;
+    }
+    if (se->conn.want & FUSE_CAP_READDIRPLUS_AUTO) {
+        outarg.flags |= FUSE_READDIRPLUS_AUTO;
+    }
+    if (se->conn.want & FUSE_CAP_ASYNC_DIO) {
+        outarg.flags |= FUSE_ASYNC_DIO;
+    }
+    if (se->conn.want & FUSE_CAP_WRITEBACK_CACHE) {
+        outarg.flags |= FUSE_WRITEBACK_CACHE;
+    }
+    if (se->conn.want & FUSE_CAP_POSIX_ACL) {
+        outarg.flags |= FUSE_POSIX_ACL;
+    }
+    outarg.max_readahead = se->conn.max_readahead;
+    outarg.max_write = se->conn.max_write;
+    if (se->conn.max_background >= (1 << 16)) {
+        se->conn.max_background = (1 << 16) - 1;
+    }
+    if (se->conn.congestion_threshold > se->conn.max_background) {
+        se->conn.congestion_threshold = se->conn.max_background;
+    }
+    if (!se->conn.congestion_threshold) {
+        se->conn.congestion_threshold = se->conn.max_background * 3 / 4;
+    }
+
+    outarg.max_background = se->conn.max_background;
+    outarg.congestion_threshold = se->conn.congestion_threshold;
+    outarg.time_gran = se->conn.time_gran;
+
+    fuse_log(FUSE_LOG_DEBUG, "   INIT: %u.%u\n", outarg.major, outarg.minor);
+    fuse_log(FUSE_LOG_DEBUG, "   flags=0x%08x\n", outarg.flags);
+    fuse_log(FUSE_LOG_DEBUG, "   max_readahead=0x%08x\n", outarg.max_readahead);
+    fuse_log(FUSE_LOG_DEBUG, "   max_write=0x%08x\n", outarg.max_write);
+    fuse_log(FUSE_LOG_DEBUG, "   max_background=%i\n", outarg.max_background);
+    fuse_log(FUSE_LOG_DEBUG, "   congestion_threshold=%i\n",
+             outarg.congestion_threshold);
+    fuse_log(FUSE_LOG_DEBUG, "   time_gran=%u\n", outarg.time_gran);
+
+    send_reply_ok(req, &outarg, outargsize);
+}
+
+static void do_destroy(fuse_req_t req, fuse_ino_t nodeid,
+                       struct fuse_mbuf_iter *iter)
+{
+    struct fuse_session *se = req->se;
+
+    (void)nodeid;
+    (void)iter;
+
+    se->got_destroy = 1;
+    se->got_init = 0;
+    if (se->op.destroy) {
+        se->op.destroy(se->userdata);
+    }
+
+    send_reply_ok(req, NULL, 0);
+}
+
+static int send_notify_iov(struct fuse_session *se, int notify_code,
+                           struct iovec *iov, int count)
+{
+    struct fuse_out_header out = {
+        .error = notify_code,
+    };
+
+    if (!se->got_init) {
+        return -ENOTCONN;
+    }
+
+    iov[0].iov_base = &out;
+    iov[0].iov_len = sizeof(struct fuse_out_header);
+
+    return fuse_send_msg(se, NULL, iov, count);
+}
+
+int fuse_lowlevel_notify_poll(struct fuse_pollhandle *ph)
+{
+    if (ph != NULL) {
+        struct fuse_notify_poll_wakeup_out outarg = {
+            .kh = ph->kh,
+        };
+        struct iovec iov[2];
+
+        iov[1].iov_base = &outarg;
+        iov[1].iov_len = sizeof(outarg);
+
+        return send_notify_iov(ph->se, FUSE_NOTIFY_POLL, iov, 2);
+    } else {
+        return 0;
+    }
+}
+
+int fuse_lowlevel_notify_inval_inode(struct fuse_session *se, fuse_ino_t ino,
+                                     off_t off, off_t len)
+{
+    struct fuse_notify_inval_inode_out outarg = {
+        .ino = ino,
+        .off = off,
+        .len = len,
+    };
+    struct iovec iov[2];
+
+    if (!se) {
+        return -EINVAL;
+    }
+
+    iov[1].iov_base = &outarg;
+    iov[1].iov_len = sizeof(outarg);
+
+    return send_notify_iov(se, FUSE_NOTIFY_INVAL_INODE, iov, 2);
+}
+
+int fuse_lowlevel_notify_inval_entry(struct fuse_session *se, fuse_ino_t parent,
+                                     const char *name, size_t namelen)
+{
+    struct fuse_notify_inval_entry_out outarg = {
+        .parent = parent,
+        .namelen = namelen,
+    };
+    struct iovec iov[3];
+
+    if (!se) {
+        return -EINVAL;
+    }
+
+    iov[1].iov_base = &outarg;
+    iov[1].iov_len = sizeof(outarg);
+    iov[2].iov_base = (void *)name;
+    iov[2].iov_len = namelen + 1;
+
+    return send_notify_iov(se, FUSE_NOTIFY_INVAL_ENTRY, iov, 3);
+}
+
+int fuse_lowlevel_notify_delete(struct fuse_session *se, fuse_ino_t parent,
+                                fuse_ino_t child, const char *name,
+                                size_t namelen)
+{
+    struct fuse_notify_delete_out outarg = {
+        .parent = parent,
+        .child = child,
+        .namelen = namelen,
+    };
+    struct iovec iov[3];
+
+    if (!se) {
+        return -EINVAL;
+    }
+
+    iov[1].iov_base = &outarg;
+    iov[1].iov_len = sizeof(outarg);
+    iov[2].iov_base = (void *)name;
+    iov[2].iov_len = namelen + 1;
+
+    return send_notify_iov(se, FUSE_NOTIFY_DELETE, iov, 3);
+}
+
+int fuse_lowlevel_notify_store(struct fuse_session *se, fuse_ino_t ino,
+                               off_t offset, struct fuse_bufvec *bufv)
+{
+    struct fuse_out_header out = {
+        .error = FUSE_NOTIFY_STORE,
+    };
+    struct fuse_notify_store_out outarg = {
+        .nodeid = ino,
+        .offset = offset,
+        .size = fuse_buf_size(bufv),
+    };
+    struct iovec iov[3];
+    int res;
+
+    if (!se) {
+        return -EINVAL;
+    }
+
+    iov[0].iov_base = &out;
+    iov[0].iov_len = sizeof(out);
+    iov[1].iov_base = &outarg;
+    iov[1].iov_len = sizeof(outarg);
+
+    res = fuse_send_data_iov(se, NULL, iov, 2, bufv);
+    if (res > 0) {
+        res = -res;
+    }
+
+    return res;
+}
+
+void *fuse_req_userdata(fuse_req_t req)
+{
+    return req->se->userdata;
+}
+
+const struct fuse_ctx *fuse_req_ctx(fuse_req_t req)
+{
+    return &req->ctx;
+}
+
+void fuse_req_interrupt_func(fuse_req_t req, fuse_interrupt_func_t func,
+                             void *data)
+{
+    pthread_mutex_lock(&req->lock);
+    pthread_mutex_lock(&req->se->lock);
+    req->u.ni.func = func;
+    req->u.ni.data = data;
+    pthread_mutex_unlock(&req->se->lock);
+    if (req->interrupted && func) {
+        func(req, data);
+    }
+    pthread_mutex_unlock(&req->lock);
+}
+
+int fuse_req_interrupted(fuse_req_t req)
+{
+    int interrupted;
+
+    pthread_mutex_lock(&req->se->lock);
+    interrupted = req->interrupted;
+    pthread_mutex_unlock(&req->se->lock);
+
+    return interrupted;
+}
+
+static struct {
+    void (*func)(fuse_req_t, fuse_ino_t, struct fuse_mbuf_iter *);
+    const char *name;
+} fuse_ll_ops[] = {
+    [FUSE_LOOKUP] = { do_lookup, "LOOKUP" },
+    [FUSE_FORGET] = { do_forget, "FORGET" },
+    [FUSE_GETATTR] = { do_getattr, "GETATTR" },
+    [FUSE_SETATTR] = { do_setattr, "SETATTR" },
+    [FUSE_READLINK] = { do_readlink, "READLINK" },
+    [FUSE_SYMLINK] = { do_symlink, "SYMLINK" },
+    [FUSE_MKNOD] = { do_mknod, "MKNOD" },
+    [FUSE_MKDIR] = { do_mkdir, "MKDIR" },
+    [FUSE_UNLINK] = { do_unlink, "UNLINK" },
+    [FUSE_RMDIR] = { do_rmdir, "RMDIR" },
+    [FUSE_RENAME] = { do_rename, "RENAME" },
+    [FUSE_LINK] = { do_link, "LINK" },
+    [FUSE_OPEN] = { do_open, "OPEN" },
+    [FUSE_READ] = { do_read, "READ" },
+    [FUSE_WRITE] = { do_write, "WRITE" },
+    [FUSE_STATFS] = { do_statfs, "STATFS" },
+    [FUSE_RELEASE] = { do_release, "RELEASE" },
+    [FUSE_FSYNC] = { do_fsync, "FSYNC" },
+    [FUSE_SETXATTR] = { do_setxattr, "SETXATTR" },
+    [FUSE_GETXATTR] = { do_getxattr, "GETXATTR" },
+    [FUSE_LISTXATTR] = { do_listxattr, "LISTXATTR" },
+    [FUSE_REMOVEXATTR] = { do_removexattr, "REMOVEXATTR" },
+    [FUSE_FLUSH] = { do_flush, "FLUSH" },
+    [FUSE_INIT] = { do_init, "INIT" },
+    [FUSE_OPENDIR] = { do_opendir, "OPENDIR" },
+    [FUSE_READDIR] = { do_readdir, "READDIR" },
+    [FUSE_RELEASEDIR] = { do_releasedir, "RELEASEDIR" },
+    [FUSE_FSYNCDIR] = { do_fsyncdir, "FSYNCDIR" },
+    [FUSE_GETLK] = { do_getlk, "GETLK" },
+    [FUSE_SETLK] = { do_setlk, "SETLK" },
+    [FUSE_SETLKW] = { do_setlkw, "SETLKW" },
+    [FUSE_ACCESS] = { do_access, "ACCESS" },
+    [FUSE_CREATE] = { do_create, "CREATE" },
+    [FUSE_INTERRUPT] = { do_interrupt, "INTERRUPT" },
+    [FUSE_BMAP] = { do_bmap, "BMAP" },
+    [FUSE_IOCTL] = { do_ioctl, "IOCTL" },
+    [FUSE_POLL] = { do_poll, "POLL" },
+    [FUSE_FALLOCATE] = { do_fallocate, "FALLOCATE" },
+    [FUSE_DESTROY] = { do_destroy, "DESTROY" },
+    [FUSE_NOTIFY_REPLY] = { NULL, "NOTIFY_REPLY" },
+    [FUSE_BATCH_FORGET] = { do_batch_forget, "BATCH_FORGET" },
+    [FUSE_READDIRPLUS] = { do_readdirplus, "READDIRPLUS" },
+    [FUSE_RENAME2] = { do_rename2, "RENAME2" },
+    [FUSE_COPY_FILE_RANGE] = { do_copy_file_range, "COPY_FILE_RANGE" },
+    [FUSE_LSEEK] = { do_lseek, "LSEEK" },
+};
+
+#define FUSE_MAXOP (sizeof(fuse_ll_ops) / sizeof(fuse_ll_ops[0]))
+
+static const char *opname(enum fuse_opcode opcode)
+{
+    if (opcode >= FUSE_MAXOP || !fuse_ll_ops[opcode].name) {
+        return "???";
+    } else {
+        return fuse_ll_ops[opcode].name;
+    }
+}
+
+void fuse_session_process_buf(struct fuse_session *se,
+                              const struct fuse_buf *buf)
+{
+    struct fuse_bufvec bufv = { .buf[0] = *buf, .count = 1 };
+    fuse_session_process_buf_int(se, &bufv, NULL);
+}
+
+/*
+ * Restriction:
+ *   bufv is normally a single entry buffer, except for a write
+ *   where (if it's in memory) then the bufv may be multiple entries,
+ *   where the first entry contains all headers and subsequent entries
+ *   contain data
+ *   bufv shall not use any offsets etc to make the data anything
+ *   other than contiguous starting from 0.
+ */
+void fuse_session_process_buf_int(struct fuse_session *se,
+                                  struct fuse_bufvec *bufv,
+                                  struct fuse_chan *ch)
+{
+    const struct fuse_buf *buf = bufv->buf;
+    struct fuse_mbuf_iter iter = FUSE_MBUF_ITER_INIT(buf);
+    struct fuse_in_header *in;
+    struct fuse_req *req;
+    int err;
+
+    /* The first buffer must be a memory buffer */
+    assert(!(buf->flags & FUSE_BUF_IS_FD));
+
+    in = fuse_mbuf_iter_advance(&iter, sizeof(*in));
+    assert(in); /* caller guarantees the input buffer is large enough */
+
+    fuse_log(
+        FUSE_LOG_DEBUG,
+        "unique: %llu, opcode: %s (%i), nodeid: %llu, insize: %zu, pid: %u\n",
+        (unsigned long long)in->unique, opname((enum fuse_opcode)in->opcode),
+        in->opcode, (unsigned long long)in->nodeid, buf->size, in->pid);
+
+    req = fuse_ll_alloc_req(se);
+    if (req == NULL) {
+        struct fuse_out_header out = {
+            .unique = in->unique,
+            .error = -ENOMEM,
+        };
+        struct iovec iov = {
+            .iov_base = &out,
+            .iov_len = sizeof(struct fuse_out_header),
+        };
+
+        fuse_send_msg(se, ch, &iov, 1);
+        return;
+    }
+
+    req->unique = in->unique;
+    req->ctx.uid = in->uid;
+    req->ctx.gid = in->gid;
+    req->ctx.pid = in->pid;
+    req->ch = ch;
+
+    /*
+     * INIT and DESTROY requests are serialized, all other request types
+     * run in parallel.  This prevents races between FUSE_INIT and ordinary
+     * requests, FUSE_INIT and FUSE_INIT, FUSE_INIT and FUSE_DESTROY, and
+     * FUSE_DESTROY and FUSE_DESTROY.
+     */
+    if (in->opcode == FUSE_INIT || in->opcode == CUSE_INIT ||
+        in->opcode == FUSE_DESTROY) {
+        pthread_rwlock_wrlock(&se->init_rwlock);
+    } else {
+        pthread_rwlock_rdlock(&se->init_rwlock);
+    }
+
+    err = EIO;
+    if (!se->got_init) {
+        enum fuse_opcode expected;
+
+        expected = se->cuse_data ? CUSE_INIT : FUSE_INIT;
+        if (in->opcode != expected) {
+            goto reply_err;
+        }
+    } else if (in->opcode == FUSE_INIT || in->opcode == CUSE_INIT) {
+        if (fuse_lowlevel_is_virtio(se)) {
+            /*
+             * TODO: This is after a hard reboot typically, we need to do
+             * a destroy, but we can't reply to this request yet so
+             * we can't use do_destroy
+             */
+            fuse_log(FUSE_LOG_DEBUG, "%s: reinit\n", __func__);
+            se->got_destroy = 1;
+            se->got_init = 0;
+            if (se->op.destroy) {
+                se->op.destroy(se->userdata);
+            }
+        } else {
+            goto reply_err;
+        }
+    }
+
+    err = EACCES;
+    /* Implement -o allow_root */
+    if (se->deny_others && in->uid != se->owner && in->uid != 0 &&
+        in->opcode != FUSE_INIT && in->opcode != FUSE_READ &&
+        in->opcode != FUSE_WRITE && in->opcode != FUSE_FSYNC &&
+        in->opcode != FUSE_RELEASE && in->opcode != FUSE_READDIR &&
+        in->opcode != FUSE_FSYNCDIR && in->opcode != FUSE_RELEASEDIR &&
+        in->opcode != FUSE_NOTIFY_REPLY && in->opcode != FUSE_READDIRPLUS) {
+        goto reply_err;
+    }
+
+    err = ENOSYS;
+    if (in->opcode >= FUSE_MAXOP || !fuse_ll_ops[in->opcode].func) {
+        goto reply_err;
+    }
+    if (in->opcode != FUSE_INTERRUPT) {
+        struct fuse_req *intr;
+        pthread_mutex_lock(&se->lock);
+        intr = check_interrupt(se, req);
+        list_add_req(req, &se->list);
+        pthread_mutex_unlock(&se->lock);
+        if (intr) {
+            fuse_reply_err(intr, EAGAIN);
+        }
+    }
+
+    if (in->opcode == FUSE_WRITE && se->op.write_buf) {
+        do_write_buf(req, in->nodeid, &iter, bufv);
+    } else {
+        fuse_ll_ops[in->opcode].func(req, in->nodeid, &iter);
+    }
+
+    pthread_rwlock_unlock(&se->init_rwlock);
+    return;
+
+reply_err:
+    fuse_reply_err(req, err);
+    pthread_rwlock_unlock(&se->init_rwlock);
+}
+
+#define LL_OPTION(n, o, v)                     \
+    {                                          \
+        n, offsetof(struct fuse_session, o), v \
+    }
+
+static const struct fuse_opt fuse_ll_opts[] = {
+    LL_OPTION("debug", debug, 1),
+    LL_OPTION("-d", debug, 1),
+    LL_OPTION("--debug", debug, 1),
+    LL_OPTION("allow_root", deny_others, 1),
+    LL_OPTION("--socket-path=%s", vu_socket_path, 0),
+    LL_OPTION("--fd=%d", vu_listen_fd, 0),
+    LL_OPTION("--thread-pool-size=%d", thread_pool_size, 0),
+    FUSE_OPT_END
+};
+
+void fuse_lowlevel_version(void)
+{
+    printf("using FUSE kernel interface version %i.%i\n", FUSE_KERNEL_VERSION,
+           FUSE_KERNEL_MINOR_VERSION);
+}
+
+void fuse_lowlevel_help(void)
+{
+    /*
+     * These are not all options, but the ones that are
+     * potentially of interest to an end-user
+     */
+    printf(
+        "    -o allow_root              allow access by root\n"
+        "    --socket-path=PATH         path for the vhost-user socket\n"
+        "    --fd=FDNUM                 fd number of vhost-user socket\n"
+        "    --thread-pool-size=NUM     thread pool size limit (default %d)\n",
+        THREAD_POOL_SIZE);
+}
+
+void fuse_session_destroy(struct fuse_session *se)
+{
+    if (se->got_init && !se->got_destroy) {
+        if (se->op.destroy) {
+            se->op.destroy(se->userdata);
+        }
+    }
+    pthread_rwlock_destroy(&se->init_rwlock);
+    pthread_mutex_destroy(&se->lock);
+    free(se->cuse_data);
+    if (se->fd != -1) {
+        close(se->fd);
+    }
+
+    if (fuse_lowlevel_is_virtio(se)) {
+        virtio_session_close(se);
+    }
+
+    free(se->vu_socket_path);
+    se->vu_socket_path = NULL;
+
+    free(se);
+}
+
+
+struct fuse_session *fuse_session_new(struct fuse_args *args,
+                                      const struct fuse_lowlevel_ops *op,
+                                      size_t op_size, void *userdata)
+{
+    struct fuse_session *se;
+
+    if (sizeof(struct fuse_lowlevel_ops) < op_size) {
+        fuse_log(
+            FUSE_LOG_ERR,
+            "fuse: warning: library too old, some operations may not work\n");
+        op_size = sizeof(struct fuse_lowlevel_ops);
+    }
+
+    if (args->argc == 0) {
+        fuse_log(FUSE_LOG_ERR,
+                 "fuse: empty argv passed to fuse_session_new().\n");
+        return NULL;
+    }
+
+    se = (struct fuse_session *)calloc(1, sizeof(struct fuse_session));
+    if (se == NULL) {
+        fuse_log(FUSE_LOG_ERR, "fuse: failed to allocate fuse object\n");
+        goto out1;
+    }
+    se->fd = -1;
+    se->vu_listen_fd = -1;
+    se->thread_pool_size = THREAD_POOL_SIZE;
+    se->conn.max_write = UINT_MAX;
+    se->conn.max_readahead = UINT_MAX;
+
+    /* Parse options */
+    if (fuse_opt_parse(args, se, fuse_ll_opts, NULL) == -1) {
+        goto out2;
+    }
+    if (args->argc == 1 && args->argv[0][0] == '-') {
+        fuse_log(FUSE_LOG_ERR,
+                 "fuse: warning: argv[0] looks like an option, but "
+                 "will be ignored\n");
+    } else if (args->argc != 1) {
+        int i;
+        fuse_log(FUSE_LOG_ERR, "fuse: unknown option(s): `");
+        for (i = 1; i < args->argc - 1; i++) {
+            fuse_log(FUSE_LOG_ERR, "%s ", args->argv[i]);
+        }
+        fuse_log(FUSE_LOG_ERR, "%s'\n", args->argv[i]);
+        goto out4;
+    }
+
+    if (!se->vu_socket_path && se->vu_listen_fd < 0) {
+        fuse_log(FUSE_LOG_ERR, "fuse: missing --socket-path or --fd option\n");
+        goto out4;
+    }
+    if (se->vu_socket_path && se->vu_listen_fd >= 0) {
+        fuse_log(FUSE_LOG_ERR,
+                 "fuse: --socket-path and --fd cannot be given together\n");
+        goto out4;
+    }
+
+    se->bufsize = FUSE_MAX_MAX_PAGES * getpagesize() + FUSE_BUFFER_HEADER_SIZE;
+
+    list_init_req(&se->list);
+    list_init_req(&se->interrupts);
+    fuse_mutex_init(&se->lock);
+    pthread_rwlock_init(&se->init_rwlock, NULL);
+
+    memcpy(&se->op, op, op_size);
+    se->owner = getuid();
+    se->userdata = userdata;
+
+    return se;
+
+out4:
+    fuse_opt_free_args(args);
+out2:
+    free(se);
+out1:
+    return NULL;
+}
+
+int fuse_session_mount(struct fuse_session *se)
+{
+    return virtio_session_mount(se);
+}
+
+int fuse_session_fd(struct fuse_session *se)
+{
+    return se->fd;
+}
+
+void fuse_session_unmount(struct fuse_session *se)
+{
+}
+
+int fuse_lowlevel_is_virtio(struct fuse_session *se)
+{
+    return !!se->virtio_dev;
+}
+
+#ifdef linux
+int fuse_req_getgroups(fuse_req_t req, int size, gid_t list[])
+{
+    char *buf;
+    size_t bufsize = 1024;
+    char path[128];
+    int ret;
+    int fd;
+    unsigned long pid = req->ctx.pid;
+    char *s;
+
+    sprintf(path, "/proc/%lu/task/%lu/status", pid, pid);
+
+retry:
+    buf = malloc(bufsize);
+    if (buf == NULL) {
+        return -ENOMEM;
+    }
+
+    ret = -EIO;
+    fd = open(path, O_RDONLY);
+    if (fd == -1) {
+        goto out_free;
+    }
+
+    ret = read(fd, buf, bufsize);
+    close(fd);
+    if (ret < 0) {
+        ret = -EIO;
+        goto out_free;
+    }
+
+    if ((size_t)ret == bufsize) {
+        free(buf);
+        bufsize *= 4;
+        goto retry;
+    }
+
+    ret = -EIO;
+    s = strstr(buf, "\nGroups:");
+    if (s == NULL) {
+        goto out_free;
+    }
+
+    s += 8;
+    ret = 0;
+    while (1) {
+        char *end;
+        unsigned long val = strtoul(s, &end, 0);
+        if (end == s) {
+            break;
+        }
+
+        s = end;
+        if (ret < size) {
+            list[ret] = val;
+        }
+        ret++;
+    }
+
+out_free:
+    free(buf);
+    return ret;
+}
+#else /* linux */
+/*
+ * This is currently not implemented on other than Linux...
+ */
+int fuse_req_getgroups(fuse_req_t req, int size, gid_t list[])
+{
+    (void)req;
+    (void)size;
+    (void)list;
+    return -ENOSYS;
+}
+#endif
+
+void fuse_session_exit(struct fuse_session *se)
+{
+    se->exited = 1;
+}
+
+void fuse_session_reset(struct fuse_session *se)
+{
+    se->exited = 0;
+    se->error = 0;
+}
+
+int fuse_session_exited(struct fuse_session *se)
+{
+    return se->exited;
+}