aboutsummaryrefslogtreecommitdiff
path: root/tools/virtiofsd/fuse_virtio.c
blob: dd1c605dbf63510f2bb335dd1ba2c91d877c53bd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
/*
 * 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 <assert.h>
#include <errno.h>
#include <glib.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/eventfd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/un.h>
#include <unistd.h>

#include "contrib/libvhost-user/libvhost-user.h"

struct fv_VuDev;
struct fv_QueueInfo {
    pthread_t thread;
    /*
     * 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 void copy_from_iov(struct fuse_buf *buf, size_t out_num,
                          const struct iovec *out_sg)
{
    void *dest = buf->mem;

    while (out_num) {
        size_t onelen = out_sg->iov_len;
        memcpy(dest, out_sg->iov_base, onelen);
        dest += onelen;
        out_sg++;
        out_num--;
    }
}

/*
 * Copy from one iov to another, the given number of bytes
 * The caller must have checked sizes.
 */
static void copy_iov(struct iovec *src_iov, int src_count,
                     struct iovec *dst_iov, int dst_count, size_t to_copy)
{
    size_t dst_offset = 0;
    /* Outer loop copies 'src' elements */
    while (to_copy) {
        assert(src_count);
        size_t src_len = src_iov[0].iov_len;
        size_t src_offset = 0;

        if (src_len > to_copy) {
            src_len = to_copy;
        }
        /* Inner loop copies contents of one 'src' to maybe multiple dst. */
        while (src_len) {
            assert(dst_count);
            size_t dst_len = dst_iov[0].iov_len - dst_offset;
            if (dst_len > src_len) {
                dst_len = src_len;
            }

            memcpy(dst_iov[0].iov_base + dst_offset,
                   src_iov[0].iov_base + src_offset, dst_len);
            src_len -= dst_len;
            to_copy -= dst_len;
            src_offset += dst_len;
            dst_offset += dst_len;

            assert(dst_offset <= dst_iov[0].iov_len);
            if (dst_offset == dst_iov[0].iov_len) {
                dst_offset = 0;
                dst_iov++;
                dst_count--;
            }
        }
        src_iov++;
        src_count--;
    }
}

/*
 * Called back by ll whenever it wants to send a reply/message back
 * The 1st element of the iov starts with the fuse_out_header
 * 'unique'==0 means it's a notify message.
 */
int virtio_send_msg(struct fuse_session *se, struct fuse_chan *ch,
                    struct iovec *iov, int count)
{
    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);

    pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock);
    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);
    pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock);

    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;

    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
     */
    struct iovec *in_sg_cpy = calloc(sizeof(struct iovec), in_num);
    assert(in_sg_cpy);
    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;
            fuse_log(FUSE_LOG_DEBUG, "%s: preadv failed (%m) len=%zd\n",
                     __func__, len);
            free(in_sg_cpy);
            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;
        }
        if (ret != len) {
            fuse_log(FUSE_LOG_DEBUG, "%s: ret!=len\n", __func__);
            ret = EIO;
            free(in_sg_cpy);
            goto err;
        }
        in_sg_left -= ret;
        len -= ret;
    } while (in_sg_left);
    free(in_sg_cpy);

    /* 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;

    pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock);
    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);
    pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock);

err:
    if (ret == 0) {
        req->reply_sent = true;
    }

    return ret;
}

/* 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;

    assert(se->bufsize > sizeof(struct fuse_in_header));

    /*
     * 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 = malloc(se->bufsize);
    assert(fbuf.mem);

    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 first element and look at it */
    copy_from_iov(&fbuf, 1, out_sg);

    pbufv = NULL; /* Compiler thinks an unitialised path */
    if (out_num > 2 &&
        out_sg[0].iov_len == sizeof(struct fuse_in_header) &&
        ((struct fuse_in_header *)fbuf.mem)->opcode == FUSE_WRITE &&
        out_sg[1].iov_len == 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__);

        /* copy the fuse_write_in header afte rthe fuse_in_header */
        fbuf.mem += out_sg->iov_len;
        copy_from_iov(&fbuf, 1, out_sg + 1);
        fbuf.mem -= out_sg->iov_len;
        fbuf.size = out_sg[0].iov_len + out_sg[1].iov_len;

        /* Allocate the bufv, with space for the rest of the iov */
        pbufv = malloc(sizeof(struct fuse_bufvec) +
                       sizeof(struct fuse_buf) * (out_num - 2));
        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;
        iovindex = 2; /* 2 headers, separate iovs */
        pbufvindex = 1; /* 2 headers, 1 fusebuf */

        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;
        }
    } else {
        /* Normal (non fast write) path */

        /* Copy the rest of the buffer */
        fbuf.mem += out_sg->iov_len;
        copy_from_iov(&fbuf, out_num - 1, out_sg + 1);
        fbuf.mem -= out_sg->iov_len;
        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) {
        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);

        pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock);
        pthread_mutex_lock(&qi->vq_lock);
        vu_queue_push(dev, q, elem, 0);
        vu_queue_notify(dev, q);
        pthread_mutex_unlock(&qi->vq_lock);
        pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock);
    }

    pthread_mutex_destroy(&req->ch.lock);
    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;

    pool = g_thread_pool_new(fv_queue_worker, qi, se->thread_pool_size, TRUE,
                             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];
        int ret;

        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() */
        ret = pthread_rwlock_rdlock(&qi->virtio_dev->vu_dispatch_rwlock);
        assert(ret == 0); /* there is no possible error case */
        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;

            g_thread_pool_push(pool, req, NULL);
        }

        pthread_mutex_unlock(&qi->vq_lock);
        pthread_rwlock_unlock(&qi->virtio_dev->vu_dispatch_rwlock);
    }

    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;
    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 = realloc(vud->qi, (qidx + 1) * sizeof(vud->qi[0]));
            assert(vud->qi);
            memset(vud->qi + vud->nqueues, 0,
                   sizeof(vud->qi[0]) * (1 + (qidx - vud->nqueues)));
            vud->nqueues = qidx + 1;
        }
        if (!vud->qi[qidx]) {
            vud->qi[qidx] = calloc(sizeof(struct fv_QueueInfo), 1);
            assert(vud->qi[qidx]);
            vud->qi[qidx]->virtio_dev = vud;
            vud->qi[qidx]->qidx = qidx;
        } else {
            /* Shouldn't have been started */
            assert(vud->qi[qidx]->kick_fd == -1);
        }
        ourqi = vud->qi[qidx];
        ourqi->kick_fd = dev->vq[qidx].kick_fd;

        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 {
        fv_queue_cleanup_thread(vud, qidx);
    }
}

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;
        int ret;
        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() */
        ret = pthread_rwlock_wrlock(&se->virtio_dev->vu_dispatch_rwlock);
        assert(ret == 0); /* there is no possible error case */

        ok = vu_dispatch(&se->virtio_dev->dev);

        pthread_rwlock_unlock(&se->virtio_dev->vu_dispatch_rwlock);

        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 to 077 and restore it later.
     */
    old_umask = umask(0077);
    if (bind(listen_sock, (struct sockaddr *)&un, addr_len) == -1) {
        fuse_log(FUSE_LOG_ERR, "vhost socket bind: %m\n");
        close(listen_sock);
        umask(old_umask);
        return -1;
    }
    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;

    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 = calloc(sizeof(struct fv_VuDev), 1);
    if (!se->virtio_dev) {
        fuse_log(FUSE_LOG_ERR, "%s: virtio_dev calloc failed\n", __func__);
        close(data_sock);
        return -1;
    }

    se->vu_socketfd = data_sock;
    se->virtio_dev->se = se;
    pthread_rwlock_init(&se->virtio_dev->vu_dispatch_rwlock, NULL);
    vu_init(&se->virtio_dev->dev, 2, se->vu_socketfd, fv_panic, fv_set_watch,
            fv_remove_watch, &fv_iface);

    return 0;
}

void virtio_session_close(struct fuse_session *se)
{
    close(se->vu_socketfd);

    if (!se->virtio_dev) {
        return;
    }

    free(se->virtio_dev->qi);
    pthread_rwlock_destroy(&se->virtio_dev->vu_dispatch_rwlock);
    free(se->virtio_dev);
    se->virtio_dev = NULL;
}