fs/fuse/virtio_fs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * virtio-fs: Virtio Filesystem
   4  * Copyright (C) 2018 Red Hat, Inc.
   5  */
   6
   7 #include <linux/fs.h>
   8 #include <linux/dax.h>
   9 #include <linux/pci.h>
  10 #include <linux/pfn_t.h>
  11 #include <linux/memremap.h>
  12 #include <linux/module.h>
  13 #include <linux/virtio.h>
  14 #include <linux/virtio_fs.h>
  15 #include <linux/delay.h>
  16 #include <linux/fs_context.h>
  17 #include <linux/fs_parser.h>
  18 #include <linux/highmem.h>
  19 #include <linux/uio.h>
  20 #include "fuse_i.h"
  21
  22 /* Used to help calculate the FUSE connection's max_pages limit for a request's
  23  * size. Parts of the struct fuse_req are sliced into scattergather lists in
  24  * addition to the pages used, so this can help account for that overhead.
  25  */
  26 #define FUSE_HEADER_OVERHEAD    4
  27
  28 /* List of virtio-fs device instances and a lock for the list. Also provides
  29  * mutual exclusion in device removal and mounting path
  30  */
  31 static DEFINE_MUTEX(virtio_fs_mutex);
  32 static LIST_HEAD(virtio_fs_instances);
  33
  34 enum {
  35         VQ_HIPRIO,
  36         VQ_REQUEST
  37 };
  38
  39 #define VQ_NAME_LEN     24
  40
  41 /* Per-virtqueue state */
  42 struct virtio_fs_vq {
  43         spinlock_t lock;
  44         struct virtqueue *vq;     /* protected by ->lock */
  45         struct work_struct done_work;
  46         struct list_head queued_reqs;
  47         struct list_head end_reqs;      /* End these requests */
  48         struct delayed_work dispatch_work;
  49         struct fuse_dev *fud;
  50         bool connected;
  51         long in_flight;
  52         struct completion in_flight_zero; /* No inflight requests */
  53         char name[VQ_NAME_LEN];
  54 } ____cacheline_aligned_in_smp;
  55
  56 /* A virtio-fs device instance */
  57 struct virtio_fs {
  58         struct kref refcount;
  59         struct list_head list;    /* on virtio_fs_instances */
  60         char *tag;
  61         struct virtio_fs_vq *vqs;
  62         unsigned int nvqs;               /* number of virtqueues */
  63         unsigned int num_request_queues; /* number of request queues */
  64         struct dax_device *dax_dev;
  65
  66         /* DAX memory window where file contents are mapped */
  67         void *window_kaddr;
  68         phys_addr_t window_phys_addr;
  69         size_t window_len;
  70 };
  71
  72 struct virtio_fs_forget_req {
  73         struct fuse_in_header ih;
  74         struct fuse_forget_in arg;
  75 };
  76
  77 struct virtio_fs_forget {
  78         /* This request can be temporarily queued on virt queue */
  79         struct list_head list;
  80         struct virtio_fs_forget_req req;
  81 };
  82
  83 struct virtio_fs_req_work {
  84         struct fuse_req *req;
  85         struct virtio_fs_vq *fsvq;
  86         struct work_struct done_work;
  87 };
  88
  89 static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
  90                                  struct fuse_req *req, bool in_flight);
  91
  92 static const struct constant_table dax_param_enums[] = {
  93         {"always",      FUSE_DAX_ALWAYS },
  94         {"never",       FUSE_DAX_NEVER },
  95         {"inode",       FUSE_DAX_INODE_USER },
  96         {}
  97 };
  98
  99 enum {
 100         OPT_DAX,
 101         OPT_DAX_ENUM,
 102 };
 103
 104 static const struct fs_parameter_spec virtio_fs_parameters[] = {
 105         fsparam_flag("dax", OPT_DAX),
 106         fsparam_enum("dax", OPT_DAX_ENUM, dax_param_enums),
 107         {}
 108 };
 109
 110 static int virtio_fs_parse_param(struct fs_context *fsc,
 111                                  struct fs_parameter *param)
 112 {
 113         struct fs_parse_result result;
 114         struct fuse_fs_context *ctx = fsc->fs_private;
 115         int opt;
 116
 117         opt = fs_parse(fsc, virtio_fs_parameters, param, &result);
 118         if (opt < 0)
 119                 return opt;
 120
 121         switch (opt) {
 122         case OPT_DAX:
 123                 ctx->dax_mode = FUSE_DAX_ALWAYS;
 124                 break;
 125         case OPT_DAX_ENUM:
 126                 ctx->dax_mode = result.uint_32;
 127                 break;
 128         default:
 129                 return -EINVAL;
 130         }
 131
 132         return 0;
 133 }
 134
 135 static void virtio_fs_free_fsc(struct fs_context *fsc)
 136 {
 137         struct fuse_fs_context *ctx = fsc->fs_private;
 138
 139         kfree(ctx);
 140 }
 141
 142 static inline struct virtio_fs_vq *vq_to_fsvq(struct virtqueue *vq)
 143 {
 144         struct virtio_fs *fs = vq->vdev->priv;
 145
 146         return &fs->vqs[vq->index];
 147 }
 148
 149 /* Should be called with fsvq->lock held. */
 150 static inline void inc_in_flight_req(struct virtio_fs_vq *fsvq)
 151 {
 152         fsvq->in_flight++;
 153 }
 154
 155 /* Should be called with fsvq->lock held. */
 156 static inline void dec_in_flight_req(struct virtio_fs_vq *fsvq)
 157 {
 158         WARN_ON(fsvq->in_flight <= 0);
 159         fsvq->in_flight--;
 160         if (!fsvq->in_flight)
 161                 complete(&fsvq->in_flight_zero);
 162 }
 163
 164 static void release_virtio_fs_obj(struct kref *ref)
 165 {
 166         struct virtio_fs *vfs = container_of(ref, struct virtio_fs, refcount);
 167
 168         kfree(vfs->vqs);
 169         kfree(vfs);
 170 }
 171
 172 /* Make sure virtiofs_mutex is held */
 173 static void virtio_fs_put(struct virtio_fs *fs)
 174 {
 175         kref_put(&fs->refcount, release_virtio_fs_obj);
 176 }
 177
 178 static void virtio_fs_fiq_release(struct fuse_iqueue *fiq)
 179 {
 180         struct virtio_fs *vfs = fiq->priv;
 181
 182         mutex_lock(&virtio_fs_mutex);
 183         virtio_fs_put(vfs);
 184         mutex_unlock(&virtio_fs_mutex);
 185 }
 186
 187 static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq)
 188 {
 189         WARN_ON(fsvq->in_flight < 0);
 190
 191         /* Wait for in flight requests to finish.*/
 192         spin_lock(&fsvq->lock);
 193         if (fsvq->in_flight) {
 194                 /* We are holding virtio_fs_mutex. There should not be any
 195                  * waiters waiting for completion.
 196                  */
 197                 reinit_completion(&fsvq->in_flight_zero);
 198                 spin_unlock(&fsvq->lock);
 199                 wait_for_completion(&fsvq->in_flight_zero);
 200         } else {
 201                 spin_unlock(&fsvq->lock);
 202         }
 203
 204         flush_work(&fsvq->done_work);
 205         flush_delayed_work(&fsvq->dispatch_work);
 206 }
 207
 208 static void virtio_fs_drain_all_queues_locked(struct virtio_fs *fs)
 209 {
 210         struct virtio_fs_vq *fsvq;
 211         int i;
 212
 213         for (i = 0; i < fs->nvqs; i++) {
 214                 fsvq = &fs->vqs[i];
 215                 virtio_fs_drain_queue(fsvq);
 216         }
 217 }
 218
 219 static void virtio_fs_drain_all_queues(struct virtio_fs *fs)
 220 {
 221         /* Provides mutual exclusion between ->remove and ->kill_sb
 222          * paths. We don't want both of these draining queue at the
 223          * same time. Current completion logic reinits completion
 224          * and that means there should not be any other thread
 225          * doing reinit or waiting for completion already.
 226          */
 227         mutex_lock(&virtio_fs_mutex);
 228         virtio_fs_drain_all_queues_locked(fs);
 229         mutex_unlock(&virtio_fs_mutex);
 230 }
 231
 232 static void virtio_fs_start_all_queues(struct virtio_fs *fs)
 233 {
 234         struct virtio_fs_vq *fsvq;
 235         int i;
 236
 237         for (i = 0; i < fs->nvqs; i++) {
 238                 fsvq = &fs->vqs[i];
 239                 spin_lock(&fsvq->lock);
 240                 fsvq->connected = true;
 241                 spin_unlock(&fsvq->lock);
 242         }
 243 }
 244
 245 /* Add a new instance to the list or return -EEXIST if tag name exists*/
 246 static int virtio_fs_add_instance(struct virtio_fs *fs)
 247 {
 248         struct virtio_fs *fs2;
 249         bool duplicate = false;
 250
 251         mutex_lock(&virtio_fs_mutex);
 252
 253         list_for_each_entry(fs2, &virtio_fs_instances, list) {
 254                 if (strcmp(fs->tag, fs2->tag) == 0)
 255                         duplicate = true;
 256         }
 257
 258         if (!duplicate)
 259                 list_add_tail(&fs->list, &virtio_fs_instances);
 260
 261         mutex_unlock(&virtio_fs_mutex);
 262
 263         if (duplicate)
 264                 return -EEXIST;
 265         return 0;
 266 }
 267
 268 /* Return the virtio_fs with a given tag, or NULL */
 269 static struct virtio_fs *virtio_fs_find_instance(const char *tag)
 270 {
 271         struct virtio_fs *fs;
 272
 273         mutex_lock(&virtio_fs_mutex);
 274
 275         list_for_each_entry(fs, &virtio_fs_instances, list) {
 276                 if (strcmp(fs->tag, tag) == 0) {
 277                         kref_get(&fs->refcount);
 278                         goto found;
 279                 }
 280         }
 281
 282         fs = NULL; /* not found */
 283
 284 found:
 285         mutex_unlock(&virtio_fs_mutex);
 286
 287         return fs;
 288 }
 289
 290 static void virtio_fs_free_devs(struct virtio_fs *fs)
 291 {
 292         unsigned int i;
 293
 294         for (i = 0; i < fs->nvqs; i++) {
 295                 struct virtio_fs_vq *fsvq = &fs->vqs[i];
 296
 297                 if (!fsvq->fud)
 298                         continue;
 299
 300                 fuse_dev_free(fsvq->fud);
 301                 fsvq->fud = NULL;
 302         }
 303 }
 304
 305 /* Read filesystem name from virtio config into fs->tag (must kfree()). */
 306 static int virtio_fs_read_tag(struct virtio_device *vdev, struct virtio_fs *fs)
 307 {
 308         char tag_buf[sizeof_field(struct virtio_fs_config, tag)];
 309         char *end;
 310         size_t len;
 311
 312         virtio_cread_bytes(vdev, offsetof(struct virtio_fs_config, tag),
 313                            &tag_buf, sizeof(tag_buf));
 314         end = memchr(tag_buf, '\0', sizeof(tag_buf));
 315         if (end == tag_buf)
 316                 return -EINVAL; /* empty tag */
 317         if (!end)
 318                 end = &tag_buf[sizeof(tag_buf)];
 319
 320         len = end - tag_buf;
 321         fs->tag = devm_kmalloc(&vdev->dev, len + 1, GFP_KERNEL);
 322         if (!fs->tag)
 323                 return -ENOMEM;
 324         memcpy(fs->tag, tag_buf, len);
 325         fs->tag[len] = '\0';
 326         return 0;
 327 }
 328
 329 /* Work function for hiprio completion */
 330 static void virtio_fs_hiprio_done_work(struct work_struct *work)
 331 {
 332         struct virtio_fs_vq *fsvq = container_of(work, struct virtio_fs_vq,
 333                                                  done_work);
 334         struct virtqueue *vq = fsvq->vq;
 335
 336         /* Free completed FUSE_FORGET requests */
 337         spin_lock(&fsvq->lock);
 338         do {
 339                 unsigned int len;
 340                 void *req;
 341
 342                 virtqueue_disable_cb(vq);
 343
 344                 while ((req = virtqueue_get_buf(vq, &len)) != NULL) {
 345                         kfree(req);
 346                         dec_in_flight_req(fsvq);
 347                 }
 348         } while (!virtqueue_enable_cb(vq) && likely(!virtqueue_is_broken(vq)));
 349         spin_unlock(&fsvq->lock);
 350 }
 351
 352 static void virtio_fs_request_dispatch_work(struct work_struct *work)
 353 {
 354         struct fuse_req *req;
 355         struct virtio_fs_vq *fsvq = container_of(work, struct virtio_fs_vq,
 356                                                  dispatch_work.work);
 357         int ret;
 358
 359         pr_debug("virtio-fs: worker %s called.\n", __func__);
 360         while (1) {
 361                 spin_lock(&fsvq->lock);
 362                 req = list_first_entry_or_null(&fsvq->end_reqs, struct fuse_req,
 363                                                list);
 364                 if (!req) {
 365                         spin_unlock(&fsvq->lock);
 366                         break;
 367                 }
 368
 369                 list_del_init(&req->list);
 370                 spin_unlock(&fsvq->lock);
 371                 fuse_request_end(req);
 372         }
 373
 374         /* Dispatch pending requests */
 375         while (1) {
 376                 spin_lock(&fsvq->lock);
 377                 req = list_first_entry_or_null(&fsvq->queued_reqs,
 378                                                struct fuse_req, list);
 379                 if (!req) {
 380                         spin_unlock(&fsvq->lock);
 381                         return;
 382                 }
 383                 list_del_init(&req->list);
 384                 spin_unlock(&fsvq->lock);
 385
 386                 ret = virtio_fs_enqueue_req(fsvq, req, true);
 387                 if (ret < 0) {
 388                         if (ret == -ENOMEM || ret == -ENOSPC) {
 389                                 spin_lock(&fsvq->lock);
 390                                 list_add_tail(&req->list, &fsvq->queued_reqs);
 391                                 schedule_delayed_work(&fsvq->dispatch_work,
 392                                                       msecs_to_jiffies(1));
 393                                 spin_unlock(&fsvq->lock);
 394                                 return;
 395                         }
 396                         req->out.h.error = ret;
 397                         spin_lock(&fsvq->lock);
 398                         dec_in_flight_req(fsvq);
 399                         spin_unlock(&fsvq->lock);
 400                         pr_err("virtio-fs: virtio_fs_enqueue_req() failed %d\n",
 401                                ret);
 402                         fuse_request_end(req);
 403                 }
 404         }
 405 }
 406
 407 /*
 408  * Returns 1 if queue is full and sender should wait a bit before sending
 409  * next request, 0 otherwise.
 410  */
 411 static int send_forget_request(struct virtio_fs_vq *fsvq,
 412                                struct virtio_fs_forget *forget,
 413                                bool in_flight)
 414 {
 415         struct scatterlist sg;
 416         struct virtqueue *vq;
 417         int ret = 0;
 418         bool notify;
 419         struct virtio_fs_forget_req *req = &forget->req;
 420
 421         spin_lock(&fsvq->lock);
 422         if (!fsvq->connected) {
 423                 if (in_flight)
 424                         dec_in_flight_req(fsvq);
 425                 kfree(forget);
 426                 goto out;
 427         }
 428
 429         sg_init_one(&sg, req, sizeof(*req));
 430         vq = fsvq->vq;
 431         dev_dbg(&vq->vdev->dev, "%s\n", __func__);
 432
 433         ret = virtqueue_add_outbuf(vq, &sg, 1, forget, GFP_ATOMIC);
 434         if (ret < 0) {
 435                 if (ret == -ENOMEM || ret == -ENOSPC) {
 436                         pr_debug("virtio-fs: Could not queue FORGET: err=%d. Will try later\n",
 437                                  ret);
 438                         list_add_tail(&forget->list, &fsvq->queued_reqs);
 439                         schedule_delayed_work(&fsvq->dispatch_work,
 440                                               msecs_to_jiffies(1));
 441                         if (!in_flight)
 442                                 inc_in_flight_req(fsvq);
 443                         /* Queue is full */
 444                         ret = 1;
 445                 } else {
 446                         pr_debug("virtio-fs: Could not queue FORGET: err=%d. Dropping it.\n",
 447                                  ret);
 448                         kfree(forget);
 449                         if (in_flight)
 450                                 dec_in_flight_req(fsvq);
 451                 }
 452                 goto out;
 453         }
 454
 455         if (!in_flight)
 456                 inc_in_flight_req(fsvq);
 457         notify = virtqueue_kick_prepare(vq);
 458         spin_unlock(&fsvq->lock);
 459
 460         if (notify)
 461                 virtqueue_notify(vq);
 462         return ret;
 463 out:
 464         spin_unlock(&fsvq->lock);
 465         return ret;
 466 }
 467
 468 static void virtio_fs_hiprio_dispatch_work(struct work_struct *work)
 469 {
 470         struct virtio_fs_forget *forget;
 471         struct virtio_fs_vq *fsvq = container_of(work, struct virtio_fs_vq,
 472                                                  dispatch_work.work);
 473         pr_debug("virtio-fs: worker %s called.\n", __func__);
 474         while (1) {
 475                 spin_lock(&fsvq->lock);
 476                 forget = list_first_entry_or_null(&fsvq->queued_reqs,
 477                                         struct virtio_fs_forget, list);
 478                 if (!forget) {
 479                         spin_unlock(&fsvq->lock);
 480                         return;
 481                 }
 482
 483                 list_del(&forget->list);
 484                 spin_unlock(&fsvq->lock);
 485                 if (send_forget_request(fsvq, forget, true))
 486                         return;
 487         }
 488 }
 489
 490 /* Allocate and copy args into req->argbuf */
 491 static int copy_args_to_argbuf(struct fuse_req *req)
 492 {
 493         struct fuse_args *args = req->args;
 494         unsigned int offset = 0;
 495         unsigned int num_in;
 496         unsigned int num_out;
 497         unsigned int len;
 498         unsigned int i;
 499
 500         num_in = args->in_numargs - args->in_pages;
 501         num_out = args->out_numargs - args->out_pages;
 502         len = fuse_len_args(num_in, (struct fuse_arg *) args->in_args) +
 503               fuse_len_args(num_out, args->out_args);
 504
 505         req->argbuf = kmalloc(len, GFP_ATOMIC);
 506         if (!req->argbuf)
 507                 return -ENOMEM;
 508
 509         for (i = 0; i < num_in; i++) {
 510                 memcpy(req->argbuf + offset,
 511                        args->in_args[i].value,
 512                        args->in_args[i].size);
 513                 offset += args->in_args[i].size;
 514         }
 515
 516         return 0;
 517 }
 518
 519 /* Copy args out of and free req->argbuf */
 520 static void copy_args_from_argbuf(struct fuse_args *args, struct fuse_req *req)
 521 {
 522         unsigned int remaining;
 523         unsigned int offset;
 524         unsigned int num_in;
 525         unsigned int num_out;
 526         unsigned int i;
 527
 528         remaining = req->out.h.len - sizeof(req->out.h);
 529         num_in = args->in_numargs - args->in_pages;
 530         num_out = args->out_numargs - args->out_pages;
 531         offset = fuse_len_args(num_in, (struct fuse_arg *)args->in_args);
 532
 533         for (i = 0; i < num_out; i++) {
 534                 unsigned int argsize = args->out_args[i].size;
 535
 536                 if (args->out_argvar &&
 537                     i == args->out_numargs - 1 &&
 538                     argsize > remaining) {
 539                         argsize = remaining;
 540                 }
 541
 542                 memcpy(args->out_args[i].value, req->argbuf + offset, argsize);
 543                 offset += argsize;
 544
 545                 if (i != args->out_numargs - 1)
 546                         remaining -= argsize;
 547         }
 548
 549         /* Store the actual size of the variable-length arg */
 550         if (args->out_argvar)
 551                 args->out_args[args->out_numargs - 1].size = remaining;
 552
 553         kfree(req->argbuf);
 554         req->argbuf = NULL;
 555 }
 556
 557 /* Work function for request completion */
 558 static void virtio_fs_request_complete(struct fuse_req *req,
 559                                        struct virtio_fs_vq *fsvq)
 560 {
 561         struct fuse_pqueue *fpq = &fsvq->fud->pq;
 562         struct fuse_args *args;
 563         struct fuse_args_pages *ap;
 564         unsigned int len, i, thislen;
 565         struct page *page;
 566
 567         /*
 568          * TODO verify that server properly follows FUSE protocol
 569          * (oh.uniq, oh.len)
 570          */
 571         args = req->args;
 572         copy_args_from_argbuf(args, req);
 573
 574         if (args->out_pages && args->page_zeroing) {
 575                 len = args->out_args[args->out_numargs - 1].size;
 576                 ap = container_of(args, typeof(*ap), args);
 577                 for (i = 0; i < ap->num_pages; i++) {
 578                         thislen = ap->descs[i].length;
 579                         if (len < thislen) {
 580                                 WARN_ON(ap->descs[i].offset);
 581                                 page = ap->pages[i];
 582                                 zero_user_segment(page, len, thislen);
 583                                 len = 0;
 584                         } else {
 585                                 len -= thislen;
 586                         }
 587                 }
 588         }
 589
 590         spin_lock(&fpq->lock);
 591         clear_bit(FR_SENT, &req->flags);
 592         spin_unlock(&fpq->lock);
 593
 594         fuse_request_end(req);
 595         spin_lock(&fsvq->lock);
 596         dec_in_flight_req(fsvq);
 597         spin_unlock(&fsvq->lock);
 598 }
 599
 600 static void virtio_fs_complete_req_work(struct work_struct *work)
 601 {
 602         struct virtio_fs_req_work *w =
 603                 container_of(work, typeof(*w), done_work);
 604
 605         virtio_fs_request_complete(w->req, w->fsvq);
 606         kfree(w);
 607 }
 608
 609 static void virtio_fs_requests_done_work(struct work_struct *work)
 610 {
 611         struct virtio_fs_vq *fsvq = container_of(work, struct virtio_fs_vq,
 612                                                  done_work);
 613         struct fuse_pqueue *fpq = &fsvq->fud->pq;
 614         struct virtqueue *vq = fsvq->vq;
 615         struct fuse_req *req;
 616         struct fuse_req *next;
 617         unsigned int len;
 618         LIST_HEAD(reqs);
 619
 620         /* Collect completed requests off the virtqueue */
 621         spin_lock(&fsvq->lock);
 622         do {
 623                 virtqueue_disable_cb(vq);
 624
 625                 while ((req = virtqueue_get_buf(vq, &len)) != NULL) {
 626                         spin_lock(&fpq->lock);
 627                         list_move_tail(&req->list, &reqs);
 628                         spin_unlock(&fpq->lock);
 629                 }
 630         } while (!virtqueue_enable_cb(vq) && likely(!virtqueue_is_broken(vq)));
 631         spin_unlock(&fsvq->lock);
 632
 633         /* End requests */
 634         list_for_each_entry_safe(req, next, &reqs, list) {
 635                 list_del_init(&req->list);
 636
 637                 /* blocking async request completes in a worker context */
 638                 if (req->args->may_block) {
 639                         struct virtio_fs_req_work *w;
 640
 641                         w = kzalloc(sizeof(*w), GFP_NOFS | __GFP_NOFAIL);
 642                         INIT_WORK(&w->done_work, virtio_fs_complete_req_work);
 643                         w->fsvq = fsvq;
 644                         w->req = req;
 645                         schedule_work(&w->done_work);
 646                 } else {
 647                         virtio_fs_request_complete(req, fsvq);
 648                 }
 649         }
 650 }
 651
 652 /* Virtqueue interrupt handler */
 653 static void virtio_fs_vq_done(struct virtqueue *vq)
 654 {
 655         struct virtio_fs_vq *fsvq = vq_to_fsvq(vq);
 656
 657         dev_dbg(&vq->vdev->dev, "%s %s\n", __func__, fsvq->name);
 658
 659         schedule_work(&fsvq->done_work);
 660 }
 661
 662 static void virtio_fs_init_vq(struct virtio_fs_vq *fsvq, char *name,
 663                               int vq_type)
 664 {
 665         strscpy(fsvq->name, name, VQ_NAME_LEN);
 666         spin_lock_init(&fsvq->lock);
 667         INIT_LIST_HEAD(&fsvq->queued_reqs);
 668         INIT_LIST_HEAD(&fsvq->end_reqs);
 669         init_completion(&fsvq->in_flight_zero);
 670
 671         if (vq_type == VQ_REQUEST) {
 672                 INIT_WORK(&fsvq->done_work, virtio_fs_requests_done_work);
 673                 INIT_DELAYED_WORK(&fsvq->dispatch_work,
 674                                   virtio_fs_request_dispatch_work);
 675         } else {
 676                 INIT_WORK(&fsvq->done_work, virtio_fs_hiprio_done_work);
 677                 INIT_DELAYED_WORK(&fsvq->dispatch_work,
 678                                   virtio_fs_hiprio_dispatch_work);
 679         }
 680 }
 681
 682 /* Initialize virtqueues */
 683 static int virtio_fs_setup_vqs(struct virtio_device *vdev,
 684                                struct virtio_fs *fs)
 685 {
 686         struct virtqueue **vqs;
 687         vq_callback_t **callbacks;
 688         const char **names;
 689         unsigned int i;
 690         int ret = 0;
 691
 692         virtio_cread_le(vdev, struct virtio_fs_config, num_request_queues,
 693                         &fs->num_request_queues);
 694         if (fs->num_request_queues == 0)
 695                 return -EINVAL;
 696
 697         fs->nvqs = VQ_REQUEST + fs->num_request_queues;
 698         fs->vqs = kcalloc(fs->nvqs, sizeof(fs->vqs[VQ_HIPRIO]), GFP_KERNEL);
 699         if (!fs->vqs)
 700                 return -ENOMEM;
 701
 702         vqs = kmalloc_array(fs->nvqs, sizeof(vqs[VQ_HIPRIO]), GFP_KERNEL);
 703         callbacks = kmalloc_array(fs->nvqs, sizeof(callbacks[VQ_HIPRIO]),
 704                                         GFP_KERNEL);
 705         names = kmalloc_array(fs->nvqs, sizeof(names[VQ_HIPRIO]), GFP_KERNEL);
 706         if (!vqs || !callbacks || !names) {
 707                 ret = -ENOMEM;
 708                 goto out;
 709         }
 710
 711         /* Initialize the hiprio/forget request virtqueue */
 712         callbacks[VQ_HIPRIO] = virtio_fs_vq_done;
 713         virtio_fs_init_vq(&fs->vqs[VQ_HIPRIO], "hiprio", VQ_HIPRIO);
 714         names[VQ_HIPRIO] = fs->vqs[VQ_HIPRIO].name;
 715
 716         /* Initialize the requests virtqueues */
 717         for (i = VQ_REQUEST; i < fs->nvqs; i++) {
 718                 char vq_name[VQ_NAME_LEN];
 719
 720                 snprintf(vq_name, VQ_NAME_LEN, "requests.%u", i - VQ_REQUEST);
 721                 virtio_fs_init_vq(&fs->vqs[i], vq_name, VQ_REQUEST);
 722                 callbacks[i] = virtio_fs_vq_done;
 723                 names[i] = fs->vqs[i].name;
 724         }
 725
 726         ret = virtio_find_vqs(vdev, fs->nvqs, vqs, callbacks, names, NULL);
 727         if (ret < 0)
 728                 goto out;
 729
 730         for (i = 0; i < fs->nvqs; i++)
 731                 fs->vqs[i].vq = vqs[i];
 732
 733         virtio_fs_start_all_queues(fs);
 734 out:
 735         kfree(names);
 736         kfree(callbacks);
 737         kfree(vqs);
 738         if (ret)
 739                 kfree(fs->vqs);
 740         return ret;
 741 }
 742
 743 /* Free virtqueues (device must already be reset) */
 744 static void virtio_fs_cleanup_vqs(struct virtio_device *vdev,
 745                                   struct virtio_fs *fs)
 746 {
 747         vdev->config->del_vqs(vdev);
 748 }
 749
 750 /* Map a window offset to a page frame number.  The window offset will have
 751  * been produced by .iomap_begin(), which maps a file offset to a window
 752  * offset.
 753  */
 754 static long virtio_fs_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
 755                                     long nr_pages, void **kaddr, pfn_t *pfn)
 756 {
 757         struct virtio_fs *fs = dax_get_private(dax_dev);
 758         phys_addr_t offset = PFN_PHYS(pgoff);
 759         size_t max_nr_pages = fs->window_len/PAGE_SIZE - pgoff;
 760
 761         if (kaddr)
 762                 *kaddr = fs->window_kaddr + offset;
 763         if (pfn)
 764                 *pfn = phys_to_pfn_t(fs->window_phys_addr + offset,
 765                                         PFN_DEV | PFN_MAP);
 766         return nr_pages > max_nr_pages ? max_nr_pages : nr_pages;
 767 }
 768
 769 static int virtio_fs_zero_page_range(struct dax_device *dax_dev,
 770                                      pgoff_t pgoff, size_t nr_pages)
 771 {
 772         long rc;
 773         void *kaddr;
 774
 775         rc = dax_direct_access(dax_dev, pgoff, nr_pages, &kaddr, NULL);
 776         if (rc < 0)
 777                 return rc;
 778         memset(kaddr, 0, nr_pages << PAGE_SHIFT);
 779         dax_flush(dax_dev, kaddr, nr_pages << PAGE_SHIFT);
 780         return 0;
 781 }
 782
 783 static const struct dax_operations virtio_fs_dax_ops = {
 784         .direct_access = virtio_fs_direct_access,
 785         .zero_page_range = virtio_fs_zero_page_range,
 786 };
 787
 788 static void virtio_fs_cleanup_dax(void *data)
 789 {
 790         struct dax_device *dax_dev = data;
 791
 792         kill_dax(dax_dev);
 793         put_dax(dax_dev);
 794 }
 795
 796 static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs)
 797 {
 798         struct virtio_shm_region cache_reg;
 799         struct dev_pagemap *pgmap;
 800         bool have_cache;
 801
 802         if (!IS_ENABLED(CONFIG_FUSE_DAX))
 803                 return 0;
 804
 805         /* Get cache region */
 806         have_cache = virtio_get_shm_region(vdev, &cache_reg,
 807                                            (u8)VIRTIO_FS_SHMCAP_ID_CACHE);
 808         if (!have_cache) {
 809                 dev_notice(&vdev->dev, "%s: No cache capability\n", __func__);
 810                 return 0;
 811         }
 812
 813         if (!devm_request_mem_region(&vdev->dev, cache_reg.addr, cache_reg.len,
 814                                      dev_name(&vdev->dev))) {
 815                 dev_warn(&vdev->dev, "could not reserve region addr=0x%llx len=0x%llx\n",
 816                          cache_reg.addr, cache_reg.len);
 817                 return -EBUSY;
 818         }
 819
 820         dev_notice(&vdev->dev, "Cache len: 0x%llx @ 0x%llx\n", cache_reg.len,
 821                    cache_reg.addr);
 822
 823         pgmap = devm_kzalloc(&vdev->dev, sizeof(*pgmap), GFP_KERNEL);
 824         if (!pgmap)
 825                 return -ENOMEM;
 826
 827         pgmap->type = MEMORY_DEVICE_FS_DAX;
 828
 829         /* Ideally we would directly use the PCI BAR resource but
 830          * devm_memremap_pages() wants its own copy in pgmap.  So
 831          * initialize a struct resource from scratch (only the start
 832          * and end fields will be used).
 833          */
 834         pgmap->range = (struct range) {
 835                 .start = (phys_addr_t) cache_reg.addr,
 836                 .end = (phys_addr_t) cache_reg.addr + cache_reg.len - 1,
 837         };
 838         pgmap->nr_range = 1;
 839
 840         fs->window_kaddr = devm_memremap_pages(&vdev->dev, pgmap);
 841         if (IS_ERR(fs->window_kaddr))
 842                 return PTR_ERR(fs->window_kaddr);
 843
 844         fs->window_phys_addr = (phys_addr_t) cache_reg.addr;
 845         fs->window_len = (phys_addr_t) cache_reg.len;
 846
 847         dev_dbg(&vdev->dev, "%s: window kaddr 0x%px phys_addr 0x%llx len 0x%llx\n",
 848                 __func__, fs->window_kaddr, cache_reg.addr, cache_reg.len);
 849
 850         fs->dax_dev = alloc_dax(fs, &virtio_fs_dax_ops);
 851         if (IS_ERR(fs->dax_dev))
 852                 return PTR_ERR(fs->dax_dev);
 853
 854         return devm_add_action_or_reset(&vdev->dev, virtio_fs_cleanup_dax,
 855                                         fs->dax_dev);
 856 }
 857
 858 static int virtio_fs_probe(struct virtio_device *vdev)
 859 {
 860         struct virtio_fs *fs;
 861         int ret;
 862
 863         fs = kzalloc(sizeof(*fs), GFP_KERNEL);
 864         if (!fs)
 865                 return -ENOMEM;
 866         kref_init(&fs->refcount);
 867         vdev->priv = fs;
 868
 869         ret = virtio_fs_read_tag(vdev, fs);
 870         if (ret < 0)
 871                 goto out;
 872
 873         ret = virtio_fs_setup_vqs(vdev, fs);
 874         if (ret < 0)
 875                 goto out;
 876
 877         /* TODO vq affinity */
 878
 879         ret = virtio_fs_setup_dax(vdev, fs);
 880         if (ret < 0)
 881                 goto out_vqs;
 882
 883         /* Bring the device online in case the filesystem is mounted and
 884          * requests need to be sent before we return.
 885          */
 886         virtio_device_ready(vdev);
 887
 888         ret = virtio_fs_add_instance(fs);
 889         if (ret < 0)
 890                 goto out_vqs;
 891
 892         return 0;
 893
 894 out_vqs:
 895         virtio_reset_device(vdev);
 896         virtio_fs_cleanup_vqs(vdev, fs);
 897         kfree(fs->vqs);
 898
 899 out:
 900         vdev->priv = NULL;
 901         kfree(fs);
 902         return ret;
 903 }
 904
 905 static void virtio_fs_stop_all_queues(struct virtio_fs *fs)
 906 {
 907         struct virtio_fs_vq *fsvq;
 908         int i;
 909
 910         for (i = 0; i < fs->nvqs; i++) {
 911                 fsvq = &fs->vqs[i];
 912                 spin_lock(&fsvq->lock);
 913                 fsvq->connected = false;
 914                 spin_unlock(&fsvq->lock);
 915         }
 916 }
 917
 918 static void virtio_fs_remove(struct virtio_device *vdev)
 919 {
 920         struct virtio_fs *fs = vdev->priv;
 921
 922         mutex_lock(&virtio_fs_mutex);
 923         /* This device is going away. No one should get new reference */
 924         list_del_init(&fs->list);
 925         virtio_fs_stop_all_queues(fs);
 926         virtio_fs_drain_all_queues_locked(fs);
 927         virtio_reset_device(vdev);
 928         virtio_fs_cleanup_vqs(vdev, fs);
 929
 930         vdev->priv = NULL;
 931         /* Put device reference on virtio_fs object */
 932         virtio_fs_put(fs);
 933         mutex_unlock(&virtio_fs_mutex);
 934 }
 935
 936 #ifdef CONFIG_PM_SLEEP
 937 static int virtio_fs_freeze(struct virtio_device *vdev)
 938 {
 939         /* TODO need to save state here */
 940         pr_warn("virtio-fs: suspend/resume not yet supported\n");
 941         return -EOPNOTSUPP;
 942 }
 943
 944 static int virtio_fs_restore(struct virtio_device *vdev)
 945 {
 946          /* TODO need to restore state here */
 947         return 0;
 948 }
 949 #endif /* CONFIG_PM_SLEEP */
 950
 951 static const struct virtio_device_id id_table[] = {
 952         { VIRTIO_ID_FS, VIRTIO_DEV_ANY_ID },
 953         {},
 954 };
 955
 956 static const unsigned int feature_table[] = {};
 957
 958 static struct virtio_driver virtio_fs_driver = {
 959         .driver.name            = KBUILD_MODNAME,
 960         .driver.owner           = THIS_MODULE,
 961         .id_table               = id_table,
 962         .feature_table          = feature_table,
 963         .feature_table_size     = ARRAY_SIZE(feature_table),
 964         .probe                  = virtio_fs_probe,
 965         .remove                 = virtio_fs_remove,
 966 #ifdef CONFIG_PM_SLEEP
 967         .freeze                 = virtio_fs_freeze,
 968         .restore                = virtio_fs_restore,
 969 #endif
 970 };
 971
 972 static void virtio_fs_wake_forget_and_unlock(struct fuse_iqueue *fiq)
 973 __releases(fiq->lock)
 974 {
 975         struct fuse_forget_link *link;
 976         struct virtio_fs_forget *forget;
 977         struct virtio_fs_forget_req *req;
 978         struct virtio_fs *fs;
 979         struct virtio_fs_vq *fsvq;
 980         u64 unique;
 981
 982         link = fuse_dequeue_forget(fiq, 1, NULL);
 983         unique = fuse_get_unique(fiq);
 984
 985         fs = fiq->priv;
 986         fsvq = &fs->vqs[VQ_HIPRIO];
 987         spin_unlock(&fiq->lock);
 988
 989         /* Allocate a buffer for the request */
 990         forget = kmalloc(sizeof(*forget), GFP_NOFS | __GFP_NOFAIL);
 991         req = &forget->req;
 992
 993         req->ih = (struct fuse_in_header){
 994                 .opcode = FUSE_FORGET,
 995                 .nodeid = link->forget_one.nodeid,
 996                 .unique = unique,
 997                 .len = sizeof(*req),
 998         };
 999         req->arg = (struct fuse_forget_in){
1000                 .nlookup = link->forget_one.nlookup,
1001         };
1002
1003         send_forget_request(fsvq, forget, false);
1004         kfree(link);
1005 }
1006
1007 static void virtio_fs_wake_interrupt_and_unlock(struct fuse_iqueue *fiq)
1008 __releases(fiq->lock)
1009 {
1010         /*
1011          * TODO interrupts.
1012          *
1013          * Normal fs operations on a local filesystems aren't interruptible.
1014          * Exceptions are blocking lock operations; for example fcntl(F_SETLKW)
1015          * with shared lock between host and guest.
1016          */
1017         spin_unlock(&fiq->lock);
1018 }
1019
1020 /* Count number of scatter-gather elements required */
1021 static unsigned int sg_count_fuse_pages(struct fuse_page_desc *page_descs,
1022                                        unsigned int num_pages,
1023                                        unsigned int total_len)
1024 {
1025         unsigned int i;
1026         unsigned int this_len;
1027
1028         for (i = 0; i < num_pages && total_len; i++) {
1029                 this_len =  min(page_descs[i].length, total_len);
1030                 total_len -= this_len;
1031         }
1032
1033         return i;
1034 }
1035
1036 /* Return the number of scatter-gather list elements required */
1037 static unsigned int sg_count_fuse_req(struct fuse_req *req)
1038 {
1039         struct fuse_args *args = req->args;
1040         struct fuse_args_pages *ap = container_of(args, typeof(*ap), args);
1041         unsigned int size, total_sgs = 1 /* fuse_in_header */;
1042
1043         if (args->in_numargs - args->in_pages)
1044                 total_sgs += 1;
1045
1046         if (args->in_pages) {
1047                 size = args->in_args[args->in_numargs - 1].size;
1048                 total_sgs += sg_count_fuse_pages(ap->descs, ap->num_pages,
1049                                                  size);
1050         }
1051
1052         if (!test_bit(FR_ISREPLY, &req->flags))
1053                 return total_sgs;
1054
1055         total_sgs += 1 /* fuse_out_header */;
1056
1057         if (args->out_numargs - args->out_pages)
1058                 total_sgs += 1;
1059
1060         if (args->out_pages) {
1061                 size = args->out_args[args->out_numargs - 1].size;
1062                 total_sgs += sg_count_fuse_pages(ap->descs, ap->num_pages,
1063                                                  size);
1064         }
1065
1066         return total_sgs;
1067 }
1068
1069 /* Add pages to scatter-gather list and return number of elements used */
1070 static unsigned int sg_init_fuse_pages(struct scatterlist *sg,
1071                                        struct page **pages,
1072                                        struct fuse_page_desc *page_descs,
1073                                        unsigned int num_pages,
1074                                        unsigned int total_len)
1075 {
1076         unsigned int i;
1077         unsigned int this_len;
1078
1079         for (i = 0; i < num_pages && total_len; i++) {
1080                 sg_init_table(&sg[i], 1);
1081                 this_len =  min(page_descs[i].length, total_len);
1082                 sg_set_page(&sg[i], pages[i], this_len, page_descs[i].offset);
1083                 total_len -= this_len;
1084         }
1085
1086         return i;
1087 }
1088
1089 /* Add args to scatter-gather list and return number of elements used */
1090 static unsigned int sg_init_fuse_args(struct scatterlist *sg,
1091                                       struct fuse_req *req,
1092                                       struct fuse_arg *args,
1093                                       unsigned int numargs,
1094                                       bool argpages,
1095                                       void *argbuf,
1096                                       unsigned int *len_used)
1097 {
1098         struct fuse_args_pages *ap = container_of(req->args, typeof(*ap), args);
1099         unsigned int total_sgs = 0;
1100         unsigned int len;
1101
1102         len = fuse_len_args(numargs - argpages, args);
1103         if (len)
1104                 sg_init_one(&sg[total_sgs++], argbuf, len);
1105
1106         if (argpages)
1107                 total_sgs += sg_init_fuse_pages(&sg[total_sgs],
1108                                                 ap->pages, ap->descs,
1109                                                 ap->num_pages,
1110                                                 args[numargs - 1].size);
1111
1112         if (len_used)
1113                 *len_used = len;
1114
1115         return total_sgs;
1116 }
1117
1118 /* Add a request to a virtqueue and kick the device */
1119 static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
1120                                  struct fuse_req *req, bool in_flight)
1121 {
1122         /* requests need at least 4 elements */
1123         struct scatterlist *stack_sgs[6];
1124         struct scatterlist stack_sg[ARRAY_SIZE(stack_sgs)];
1125         struct scatterlist **sgs = stack_sgs;
1126         struct scatterlist *sg = stack_sg;
1127         struct virtqueue *vq;
1128         struct fuse_args *args = req->args;
1129         unsigned int argbuf_used = 0;
1130         unsigned int out_sgs = 0;
1131         unsigned int in_sgs = 0;
1132         unsigned int total_sgs;
1133         unsigned int i;
1134         int ret;
1135         bool notify;
1136         struct fuse_pqueue *fpq;
1137
1138         /* Does the sglist fit on the stack? */
1139         total_sgs = sg_count_fuse_req(req);
1140         if (total_sgs > ARRAY_SIZE(stack_sgs)) {
1141                 sgs = kmalloc_array(total_sgs, sizeof(sgs[0]), GFP_ATOMIC);
1142                 sg = kmalloc_array(total_sgs, sizeof(sg[0]), GFP_ATOMIC);
1143                 if (!sgs || !sg) {
1144                         ret = -ENOMEM;
1145                         goto out;
1146                 }
1147         }
1148
1149         /* Use a bounce buffer since stack args cannot be mapped */
1150         ret = copy_args_to_argbuf(req);
1151         if (ret < 0)
1152                 goto out;
1153
1154         /* Request elements */
1155         sg_init_one(&sg[out_sgs++], &req->in.h, sizeof(req->in.h));
1156         out_sgs += sg_init_fuse_args(&sg[out_sgs], req,
1157                                      (struct fuse_arg *)args->in_args,
1158                                      args->in_numargs, args->in_pages,
1159                                      req->argbuf, &argbuf_used);
1160
1161         /* Reply elements */
1162         if (test_bit(FR_ISREPLY, &req->flags)) {
1163                 sg_init_one(&sg[out_sgs + in_sgs++],
1164                             &req->out.h, sizeof(req->out.h));
1165                 in_sgs += sg_init_fuse_args(&sg[out_sgs + in_sgs], req,
1166                                             args->out_args, args->out_numargs,
1167                                             args->out_pages,
1168                                             req->argbuf + argbuf_used, NULL);
1169         }
1170
1171         WARN_ON(out_sgs + in_sgs != total_sgs);
1172
1173         for (i = 0; i < total_sgs; i++)
1174                 sgs[i] = &sg[i];
1175
1176         spin_lock(&fsvq->lock);
1177
1178         if (!fsvq->connected) {
1179                 spin_unlock(&fsvq->lock);
1180                 ret = -ENOTCONN;
1181                 goto out;
1182         }
1183
1184         vq = fsvq->vq;
1185         ret = virtqueue_add_sgs(vq, sgs, out_sgs, in_sgs, req, GFP_ATOMIC);
1186         if (ret < 0) {
1187                 spin_unlock(&fsvq->lock);
1188                 goto out;
1189         }
1190
1191         /* Request successfully sent. */
1192         fpq = &fsvq->fud->pq;
1193         spin_lock(&fpq->lock);
1194         list_add_tail(&req->list, fpq->processing);
1195         spin_unlock(&fpq->lock);
1196         set_bit(FR_SENT, &req->flags);
1197         /* matches barrier in request_wait_answer() */
1198         smp_mb__after_atomic();
1199
1200         if (!in_flight)
1201                 inc_in_flight_req(fsvq);
1202         notify = virtqueue_kick_prepare(vq);
1203
1204         spin_unlock(&fsvq->lock);
1205
1206         if (notify)
1207                 virtqueue_notify(vq);
1208
1209 out:
1210         if (ret < 0 && req->argbuf) {
1211                 kfree(req->argbuf);
1212                 req->argbuf = NULL;
1213         }
1214         if (sgs != stack_sgs) {
1215                 kfree(sgs);
1216                 kfree(sg);
1217         }
1218
1219         return ret;
1220 }
1221
1222 static void virtio_fs_wake_pending_and_unlock(struct fuse_iqueue *fiq)
1223 __releases(fiq->lock)
1224 {
1225         unsigned int queue_id = VQ_REQUEST; /* TODO multiqueue */
1226         struct virtio_fs *fs;
1227         struct fuse_req *req;
1228         struct virtio_fs_vq *fsvq;
1229         int ret;
1230
1231         WARN_ON(list_empty(&fiq->pending));
1232         req = list_last_entry(&fiq->pending, struct fuse_req, list);
1233         clear_bit(FR_PENDING, &req->flags);
1234         list_del_init(&req->list);
1235         WARN_ON(!list_empty(&fiq->pending));
1236         spin_unlock(&fiq->lock);
1237
1238         fs = fiq->priv;
1239
1240         pr_debug("%s: opcode %u unique %#llx nodeid %#llx in.len %u out.len %u\n",
1241                   __func__, req->in.h.opcode, req->in.h.unique,
1242                  req->in.h.nodeid, req->in.h.len,
1243                  fuse_len_args(req->args->out_numargs, req->args->out_args));
1244
1245         fsvq = &fs->vqs[queue_id];
1246         ret = virtio_fs_enqueue_req(fsvq, req, false);
1247         if (ret < 0) {
1248                 if (ret == -ENOMEM || ret == -ENOSPC) {
1249                         /*
1250                          * Virtqueue full. Retry submission from worker
1251                          * context as we might be holding fc->bg_lock.
1252                          */
1253                         spin_lock(&fsvq->lock);
1254                         list_add_tail(&req->list, &fsvq->queued_reqs);
1255                         inc_in_flight_req(fsvq);
1256                         schedule_delayed_work(&fsvq->dispatch_work,
1257                                                 msecs_to_jiffies(1));
1258                         spin_unlock(&fsvq->lock);
1259                         return;
1260                 }
1261                 req->out.h.error = ret;
1262                 pr_err("virtio-fs: virtio_fs_enqueue_req() failed %d\n", ret);
1263
1264                 /* Can't end request in submission context. Use a worker */
1265                 spin_lock(&fsvq->lock);
1266                 list_add_tail(&req->list, &fsvq->end_reqs);
1267                 schedule_delayed_work(&fsvq->dispatch_work, 0);
1268                 spin_unlock(&fsvq->lock);
1269                 return;
1270         }
1271 }
1272
1273 static const struct fuse_iqueue_ops virtio_fs_fiq_ops = {
1274         .wake_forget_and_unlock         = virtio_fs_wake_forget_and_unlock,
1275         .wake_interrupt_and_unlock      = virtio_fs_wake_interrupt_and_unlock,
1276         .wake_pending_and_unlock        = virtio_fs_wake_pending_and_unlock,
1277         .release                        = virtio_fs_fiq_release,
1278 };
1279
1280 static inline void virtio_fs_ctx_set_defaults(struct fuse_fs_context *ctx)
1281 {
1282         ctx->rootmode = S_IFDIR;
1283         ctx->default_permissions = 1;
1284         ctx->allow_other = 1;
1285         ctx->max_read = UINT_MAX;
1286         ctx->blksize = 512;
1287         ctx->destroy = true;
1288         ctx->no_control = true;
1289         ctx->no_force_umount = true;
1290 }
1291
1292 static int virtio_fs_fill_super(struct super_block *sb, struct fs_context *fsc)
1293 {
1294         struct fuse_mount *fm = get_fuse_mount_super(sb);
1295         struct fuse_conn *fc = fm->fc;
1296         struct virtio_fs *fs = fc->iq.priv;
1297         struct fuse_fs_context *ctx = fsc->fs_private;
1298         unsigned int i;
1299         int err;
1300
1301         virtio_fs_ctx_set_defaults(ctx);
1302         mutex_lock(&virtio_fs_mutex);
1303
1304         /* After holding mutex, make sure virtiofs device is still there.
1305          * Though we are holding a reference to it, drive ->remove might
1306          * still have cleaned up virtual queues. In that case bail out.
1307          */
1308         err = -EINVAL;
1309         if (list_empty(&fs->list)) {
1310                 pr_info("virtio-fs: tag <%s> not found\n", fs->tag);
1311                 goto err;
1312         }
1313
1314         err = -ENOMEM;
1315         /* Allocate fuse_dev for hiprio and notification queues */
1316         for (i = 0; i < fs->nvqs; i++) {
1317                 struct virtio_fs_vq *fsvq = &fs->vqs[i];
1318
1319                 fsvq->fud = fuse_dev_alloc();
1320                 if (!fsvq->fud)
1321                         goto err_free_fuse_devs;
1322         }
1323
1324         /* virtiofs allocates and installs its own fuse devices */
1325         ctx->fudptr = NULL;
1326         if (ctx->dax_mode != FUSE_DAX_NEVER) {
1327                 if (ctx->dax_mode == FUSE_DAX_ALWAYS && !fs->dax_dev) {
1328                         err = -EINVAL;
1329                         pr_err("virtio-fs: dax can't be enabled as filesystem"
1330                                " device does not support it.\n");
1331                         goto err_free_fuse_devs;
1332                 }
1333                 ctx->dax_dev = fs->dax_dev;
1334         }
1335         err = fuse_fill_super_common(sb, ctx);
1336         if (err < 0)
1337                 goto err_free_fuse_devs;
1338
1339         for (i = 0; i < fs->nvqs; i++) {
1340                 struct virtio_fs_vq *fsvq = &fs->vqs[i];
1341
1342                 fuse_dev_install(fsvq->fud, fc);
1343         }
1344
1345         /* Previous unmount will stop all queues. Start these again */
1346         virtio_fs_start_all_queues(fs);
1347         fuse_send_init(fm);
1348         mutex_unlock(&virtio_fs_mutex);
1349         return 0;
1350
1351 err_free_fuse_devs:
1352         virtio_fs_free_devs(fs);
1353 err:
1354         mutex_unlock(&virtio_fs_mutex);
1355         return err;
1356 }
1357
1358 static void virtio_fs_conn_destroy(struct fuse_mount *fm)
1359 {
1360         struct fuse_conn *fc = fm->fc;
1361         struct virtio_fs *vfs = fc->iq.priv;
1362         struct virtio_fs_vq *fsvq = &vfs->vqs[VQ_HIPRIO];
1363
1364         /* Stop dax worker. Soon evict_inodes() will be called which
1365          * will free all memory ranges belonging to all inodes.
1366          */
1367         if (IS_ENABLED(CONFIG_FUSE_DAX))
1368                 fuse_dax_cancel_work(fc);
1369
1370         /* Stop forget queue. Soon destroy will be sent */
1371         spin_lock(&fsvq->lock);
1372         fsvq->connected = false;
1373         spin_unlock(&fsvq->lock);
1374         virtio_fs_drain_all_queues(vfs);
1375
1376         fuse_conn_destroy(fm);
1377
1378         /* fuse_conn_destroy() must have sent destroy. Stop all queues
1379          * and drain one more time and free fuse devices. Freeing fuse
1380          * devices will drop their reference on fuse_conn and that in
1381          * turn will drop its reference on virtio_fs object.
1382          */
1383         virtio_fs_stop_all_queues(vfs);
1384         virtio_fs_drain_all_queues(vfs);
1385         virtio_fs_free_devs(vfs);
1386 }
1387
1388 static void virtio_kill_sb(struct super_block *sb)
1389 {
1390         struct fuse_mount *fm = get_fuse_mount_super(sb);
1391         bool last;
1392
1393         /* If mount failed, we can still be called without any fc */
1394         if (sb->s_root) {
1395                 last = fuse_mount_remove(fm);
1396                 if (last)
1397                         virtio_fs_conn_destroy(fm);
1398         }
1399         kill_anon_super(sb);
1400         fuse_mount_destroy(fm);
1401 }
1402
1403 static int virtio_fs_test_super(struct super_block *sb,
1404                                 struct fs_context *fsc)
1405 {
1406         struct fuse_mount *fsc_fm = fsc->s_fs_info;
1407         struct fuse_mount *sb_fm = get_fuse_mount_super(sb);
1408
1409         return fsc_fm->fc->iq.priv == sb_fm->fc->iq.priv;
1410 }
1411
1412 static int virtio_fs_get_tree(struct fs_context *fsc)
1413 {
1414         struct virtio_fs *fs;
1415         struct super_block *sb;
1416         struct fuse_conn *fc = NULL;
1417         struct fuse_mount *fm;
1418         unsigned int virtqueue_size;
1419         int err = -EIO;
1420
1421         /* This gets a reference on virtio_fs object. This ptr gets installed
1422          * in fc->iq->priv. Once fuse_conn is going away, it calls ->put()
1423          * to drop the reference to this object.
1424          */
1425         fs = virtio_fs_find_instance(fsc->source);
1426         if (!fs) {
1427                 pr_info("virtio-fs: tag <%s> not found\n", fsc->source);
1428                 return -EINVAL;
1429         }
1430
1431         virtqueue_size = virtqueue_get_vring_size(fs->vqs[VQ_REQUEST].vq);
1432         if (WARN_ON(virtqueue_size <= FUSE_HEADER_OVERHEAD))
1433                 goto out_err;
1434
1435         err = -ENOMEM;
1436         fc = kzalloc(sizeof(struct fuse_conn), GFP_KERNEL);
1437         if (!fc)
1438                 goto out_err;
1439
1440         fm = kzalloc(sizeof(struct fuse_mount), GFP_KERNEL);
1441         if (!fm)
1442                 goto out_err;
1443
1444         fuse_conn_init(fc, fm, fsc->user_ns, &virtio_fs_fiq_ops, fs);
1445         fc->release = fuse_free_conn;
1446         fc->delete_stale = true;
1447         fc->auto_submounts = true;
1448         fc->sync_fs = true;
1449
1450         /* Tell FUSE to split requests that exceed the virtqueue's size */
1451         fc->max_pages_limit = min_t(unsigned int, fc->max_pages_limit,
1452                                     virtqueue_size - FUSE_HEADER_OVERHEAD);
1453
1454         fsc->s_fs_info = fm;
1455         sb = sget_fc(fsc, virtio_fs_test_super, set_anon_super_fc);
1456         if (fsc->s_fs_info)
1457                 fuse_mount_destroy(fm);
1458         if (IS_ERR(sb))
1459                 return PTR_ERR(sb);
1460
1461         if (!sb->s_root) {
1462                 err = virtio_fs_fill_super(sb, fsc);
1463                 if (err) {
1464                         deactivate_locked_super(sb);
1465                         return err;
1466                 }
1467
1468                 sb->s_flags |= SB_ACTIVE;
1469         }
1470
1471         WARN_ON(fsc->root);
1472         fsc->root = dget(sb->s_root);
1473         return 0;
1474
1475 out_err:
1476         kfree(fc);
1477         mutex_lock(&virtio_fs_mutex);
1478         virtio_fs_put(fs);
1479         mutex_unlock(&virtio_fs_mutex);
1480         return err;
1481 }
1482
1483 static const struct fs_context_operations virtio_fs_context_ops = {
1484         .free           = virtio_fs_free_fsc,
1485         .parse_param    = virtio_fs_parse_param,
1486         .get_tree       = virtio_fs_get_tree,
1487 };
1488
1489 static int virtio_fs_init_fs_context(struct fs_context *fsc)
1490 {
1491         struct fuse_fs_context *ctx;
1492
1493         if (fsc->purpose == FS_CONTEXT_FOR_SUBMOUNT)
1494                 return fuse_init_fs_context_submount(fsc);
1495
1496         ctx = kzalloc(sizeof(struct fuse_fs_context), GFP_KERNEL);
1497         if (!ctx)
1498                 return -ENOMEM;
1499         fsc->fs_private = ctx;
1500         fsc->ops = &virtio_fs_context_ops;
1501         return 0;
1502 }
1503
1504 static struct file_system_type virtio_fs_type = {
1505         .owner          = THIS_MODULE,
1506         .name           = "virtiofs",
1507         .init_fs_context = virtio_fs_init_fs_context,
1508         .kill_sb        = virtio_kill_sb,
1509 };
1510
1511 static int __init virtio_fs_init(void)
1512 {
1513         int ret;
1514
1515         ret = register_virtio_driver(&virtio_fs_driver);
1516         if (ret < 0)
1517                 return ret;
1518
1519         ret = register_filesystem(&virtio_fs_type);
1520         if (ret < 0) {
1521                 unregister_virtio_driver(&virtio_fs_driver);
1522                 return ret;
1523         }
1524
1525         return 0;
1526 }
1527 module_init(virtio_fs_init);
1528
1529 static void __exit virtio_fs_exit(void)
1530 {
1531         unregister_filesystem(&virtio_fs_type);
1532         unregister_virtio_driver(&virtio_fs_driver);
1533 }
1534 module_exit(virtio_fs_exit);
1535
1536 MODULE_AUTHOR("Stefan Hajnoczi <[email protected]>");
1537 MODULE_DESCRIPTION("Virtio Filesystem");
1538 MODULE_LICENSE("GPL");
1539 MODULE_ALIAS_FS(KBUILD_MODNAME);
1540 MODULE_DEVICE_TABLE(virtio, id_table);