fs/fuse/dev.c

   1 /*
   2   FUSE: Filesystem in Userspace
   3   Copyright (C) 2001-2008  Miklos Szeredi <miklos@szeredi.hu>
   4
   5   This program can be distributed under the terms of the GNU GPL.
   6   See the file COPYING.
   7 */
   8
   9 #include "fuse_i.h"
  10
  11 #include <linux/init.h>
  12 #include <linux/module.h>
  13 #include <linux/poll.h>
  14 #include <linux/sched/signal.h>
  15 #include <linux/uio.h>
  16 #include <linux/miscdevice.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/file.h>
  19 #include <linux/slab.h>
  20 #include <linux/pipe_fs_i.h>
  21 #include <linux/swap.h>
  22 #include <linux/splice.h>
  23 #include <linux/sched.h>
  24
  25 MODULE_ALIAS_MISCDEV(FUSE_MINOR);
  26 MODULE_ALIAS("devname:fuse");
  27
  28 /* Ordinary requests have even IDs, while interrupts IDs are odd */
  29 #define FUSE_INT_REQ_BIT (1ULL << 0)
  30 #define FUSE_REQ_ID_STEP (1ULL << 1)
  31
  32 static struct kmem_cache *fuse_req_cachep;
  33
  34 static struct fuse_dev *fuse_get_dev(struct file *file)
  35 {
  36         /*
  37          * Lockless access is OK, because file->private data is set
  38          * once during mount and is valid until the file is released.
  39          */
  40         return READ_ONCE(file->private_data);
  41 }
  42
  43 static void fuse_request_init(struct fuse_mount *fm, struct fuse_req *req)
  44 {
  45         INIT_LIST_HEAD(&req->list);
  46         INIT_LIST_HEAD(&req->intr_entry);
  47         init_waitqueue_head(&req->waitq);
  48         refcount_set(&req->count, 1);
  49         __set_bit(FR_PENDING, &req->flags);
  50         req->fm = fm;
  51 }
  52
  53 static struct fuse_req *fuse_request_alloc(struct fuse_mount *fm, gfp_t flags)
  54 {
  55         struct fuse_req *req = kmem_cache_zalloc(fuse_req_cachep, flags);
  56         if (req)
  57                 fuse_request_init(fm, req);
  58
  59         return req;
  60 }
  61
  62 static void fuse_request_free(struct fuse_req *req)
  63 {
  64         kmem_cache_free(fuse_req_cachep, req);
  65 }
  66
  67 static void __fuse_get_request(struct fuse_req *req)
  68 {
  69         refcount_inc(&req->count);
  70 }
  71
  72 /* Must be called with > 1 refcount */
  73 static void __fuse_put_request(struct fuse_req *req)
  74 {
  75         refcount_dec(&req->count);
  76 }
  77
  78 void fuse_set_initialized(struct fuse_conn *fc)
  79 {
  80         /* Make sure stores before this are seen on another CPU */
  81         smp_wmb();
  82         fc->initialized = 1;
  83 }
  84
  85 static bool fuse_block_alloc(struct fuse_conn *fc, bool for_background)
  86 {
  87         return !fc->initialized || (for_background && fc->blocked);
  88 }
  89
  90 static void fuse_drop_waiting(struct fuse_conn *fc)
  91 {
  92         /*
  93          * lockess check of fc->connected is okay, because atomic_dec_and_test()
  94          * provides a memory barrier matched with the one in fuse_wait_aborted()
  95          * to ensure no wake-up is missed.
  96          */
  97         if (atomic_dec_and_test(&fc->num_waiting) &&
  98             !READ_ONCE(fc->connected)) {
  99                 /* wake up aborters */
 100                 wake_up_all(&fc->blocked_waitq);
 101         }
 102 }
 103
 104 static void fuse_put_request(struct fuse_req *req);
 105
 106 static struct fuse_req *fuse_get_req(struct fuse_mount *fm, bool for_background)
 107 {
 108         struct fuse_conn *fc = fm->fc;
 109         struct fuse_req *req;
 110         int err;
 111         atomic_inc(&fc->num_waiting);
 112
 113         if (fuse_block_alloc(fc, for_background)) {
 114                 err = -EINTR;
 115                 if (wait_event_killable_exclusive(fc->blocked_waitq,
 116                                 !fuse_block_alloc(fc, for_background)))
 117                         goto out;
 118         }
 119         /* Matches smp_wmb() in fuse_set_initialized() */
 120         smp_rmb();
 121
 122         err = -ENOTCONN;
 123         if (!fc->connected)
 124                 goto out;
 125
 126         err = -ECONNREFUSED;
 127         if (fc->conn_error)
 128                 goto out;
 129
 130         req = fuse_request_alloc(fm, GFP_KERNEL);
 131         err = -ENOMEM;
 132         if (!req) {
 133                 if (for_background)
 134                         wake_up(&fc->blocked_waitq);
 135                 goto out;
 136         }
 137
 138         req->in.h.uid = from_kuid(fc->user_ns, current_fsuid());
 139         req->in.h.gid = from_kgid(fc->user_ns, current_fsgid());
 140         req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns);
 141
 142         __set_bit(FR_WAITING, &req->flags);
 143         if (for_background)
 144                 __set_bit(FR_BACKGROUND, &req->flags);
 145
 146         if (unlikely(req->in.h.uid == ((uid_t)-1) ||
 147                      req->in.h.gid == ((gid_t)-1))) {
 148                 fuse_put_request(req);
 149                 return ERR_PTR(-EOVERFLOW);
 150         }
 151         return req;
 152
 153  out:
 154         fuse_drop_waiting(fc);
 155         return ERR_PTR(err);
 156 }
 157
 158 static void fuse_put_request(struct fuse_req *req)
 159 {
 160         struct fuse_conn *fc = req->fm->fc;
 161
 162         if (refcount_dec_and_test(&req->count)) {
 163                 if (test_bit(FR_BACKGROUND, &req->flags)) {
 164                         /*
 165                          * We get here in the unlikely case that a background
 166                          * request was allocated but not sent
 167                          */
 168                         spin_lock(&fc->bg_lock);
 169                         if (!fc->blocked)
 170                                 wake_up(&fc->blocked_waitq);
 171                         spin_unlock(&fc->bg_lock);
 172                 }
 173
 174                 if (test_bit(FR_WAITING, &req->flags)) {
 175                         __clear_bit(FR_WAITING, &req->flags);
 176                         fuse_drop_waiting(fc);
 177                 }
 178
 179                 fuse_request_free(req);
 180         }
 181 }
 182
 183 unsigned int fuse_len_args(unsigned int numargs, struct fuse_arg *args)
 184 {
 185         unsigned nbytes = 0;
 186         unsigned i;
 187
 188         for (i = 0; i < numargs; i++)
 189                 nbytes += args[i].size;
 190
 191         return nbytes;
 192 }
 193 EXPORT_SYMBOL_GPL(fuse_len_args);
 194
 195 u64 fuse_get_unique(struct fuse_iqueue *fiq)
 196 {
 197         fiq->reqctr += FUSE_REQ_ID_STEP;
 198         return fiq->reqctr;
 199 }
 200 EXPORT_SYMBOL_GPL(fuse_get_unique);
 201
 202 static unsigned int fuse_req_hash(u64 unique)
 203 {
 204         return hash_long(unique & ~FUSE_INT_REQ_BIT, FUSE_PQ_HASH_BITS);
 205 }
 206
 207 /**
 208  * A new request is available, wake fiq->waitq
 209  */
 210 static void fuse_dev_wake_and_unlock(struct fuse_iqueue *fiq)
 211 __releases(fiq->lock)
 212 {
 213         wake_up(&fiq->waitq);
 214         kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
 215         spin_unlock(&fiq->lock);
 216 }
 217
 218 const struct fuse_iqueue_ops fuse_dev_fiq_ops = {
 219         .wake_forget_and_unlock         = fuse_dev_wake_and_unlock,
 220         .wake_interrupt_and_unlock      = fuse_dev_wake_and_unlock,
 221         .wake_pending_and_unlock        = fuse_dev_wake_and_unlock,
 222 };
 223 EXPORT_SYMBOL_GPL(fuse_dev_fiq_ops);
 224
 225 static void queue_request_and_unlock(struct fuse_iqueue *fiq,
 226                                      struct fuse_req *req)
 227 __releases(fiq->lock)
 228 {
 229         req->in.h.len = sizeof(struct fuse_in_header) +
 230                 fuse_len_args(req->args->in_numargs,
 231                               (struct fuse_arg *) req->args->in_args);
 232         list_add_tail(&req->list, &fiq->pending);
 233         fiq->ops->wake_pending_and_unlock(fiq);
 234 }
 235
 236 void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
 237                        u64 nodeid, u64 nlookup)
 238 {
 239         struct fuse_iqueue *fiq = &fc->iq;
 240
 241         forget->forget_one.nodeid = nodeid;
 242         forget->forget_one.nlookup = nlookup;
 243
 244         spin_lock(&fiq->lock);
 245         if (fiq->connected) {
 246                 fiq->forget_list_tail->next = forget;
 247                 fiq->forget_list_tail = forget;
 248                 fiq->ops->wake_forget_and_unlock(fiq);
 249         } else {
 250                 kfree(forget);
 251                 spin_unlock(&fiq->lock);
 252         }
 253 }
 254
 255 static void flush_bg_queue(struct fuse_conn *fc)
 256 {
 257         struct fuse_iqueue *fiq = &fc->iq;
 258
 259         while (fc->active_background < fc->max_background &&
 260                !list_empty(&fc->bg_queue)) {
 261                 struct fuse_req *req;
 262
 263                 req = list_first_entry(&fc->bg_queue, struct fuse_req, list);
 264                 list_del(&req->list);
 265                 fc->active_background++;
 266                 spin_lock(&fiq->lock);
 267                 req->in.h.unique = fuse_get_unique(fiq);
 268                 queue_request_and_unlock(fiq, req);
 269         }
 270 }
 271
 272 /*
 273  * This function is called when a request is finished.  Either a reply
 274  * has arrived or it was aborted (and not yet sent) or some error
 275  * occurred during communication with userspace, or the device file
 276  * was closed.  The requester thread is woken up (if still waiting),
 277  * the 'end' callback is called if given, else the reference to the
 278  * request is released
 279  */
 280 void fuse_request_end(struct fuse_req *req)
 281 {
 282         struct fuse_mount *fm = req->fm;
 283         struct fuse_conn *fc = fm->fc;
 284         struct fuse_iqueue *fiq = &fc->iq;
 285
 286         if (test_and_set_bit(FR_FINISHED, &req->flags))
 287                 goto put_request;
 288
 289         /*
 290          * test_and_set_bit() implies smp_mb() between bit
 291          * changing and below FR_INTERRUPTED check. Pairs with
 292          * smp_mb() from queue_interrupt().
 293          */
 294         if (test_bit(FR_INTERRUPTED, &req->flags)) {
 295                 spin_lock(&fiq->lock);
 296                 list_del_init(&req->intr_entry);
 297                 spin_unlock(&fiq->lock);
 298         }
 299         WARN_ON(test_bit(FR_PENDING, &req->flags));
 300         WARN_ON(test_bit(FR_SENT, &req->flags));
 301         if (test_bit(FR_BACKGROUND, &req->flags)) {
 302                 spin_lock(&fc->bg_lock);
 303                 clear_bit(FR_BACKGROUND, &req->flags);
 304                 if (fc->num_background == fc->max_background) {
 305                         fc->blocked = 0;
 306                         wake_up(&fc->blocked_waitq);
 307                 } else if (!fc->blocked) {
 308                         /*
 309                          * Wake up next waiter, if any.  It's okay to use
 310                          * waitqueue_active(), as we've already synced up
 311                          * fc->blocked with waiters with the wake_up() call
 312                          * above.
 313                          */
 314                         if (waitqueue_active(&fc->blocked_waitq))
 315                                 wake_up(&fc->blocked_waitq);
 316                 }
 317
 318                 fc->num_background--;
 319                 fc->active_background--;
 320                 flush_bg_queue(fc);
 321                 spin_unlock(&fc->bg_lock);
 322         } else {
 323                 /* Wake up waiter sleeping in request_wait_answer() */
 324                 wake_up(&req->waitq);
 325         }
 326
 327         if (test_bit(FR_ASYNC, &req->flags))
 328                 req->args->end(fm, req->args, req->out.h.error);
 329 put_request:
 330         fuse_put_request(req);
 331 }
 332 EXPORT_SYMBOL_GPL(fuse_request_end);
 333
 334 static int queue_interrupt(struct fuse_req *req)
 335 {
 336         struct fuse_iqueue *fiq = &req->fm->fc->iq;
 337
 338         spin_lock(&fiq->lock);
 339         /* Check for we've sent request to interrupt this req */
 340         if (unlikely(!test_bit(FR_INTERRUPTED, &req->flags))) {
 341                 spin_unlock(&fiq->lock);
 342                 return -EINVAL;
 343         }
 344
 345         if (list_empty(&req->intr_entry)) {
 346                 list_add_tail(&req->intr_entry, &fiq->interrupts);
 347                 /*
 348                  * Pairs with smp_mb() implied by test_and_set_bit()
 349                  * from fuse_request_end().
 350                  */
 351                 smp_mb();
 352                 if (test_bit(FR_FINISHED, &req->flags)) {
 353                         list_del_init(&req->intr_entry);
 354                         spin_unlock(&fiq->lock);
 355                         return 0;
 356                 }
 357                 fiq->ops->wake_interrupt_and_unlock(fiq);
 358         } else {
 359                 spin_unlock(&fiq->lock);
 360         }
 361         return 0;
 362 }
 363
 364 static void request_wait_answer(struct fuse_req *req)
 365 {
 366         struct fuse_conn *fc = req->fm->fc;
 367         struct fuse_iqueue *fiq = &fc->iq;
 368         int err;
 369
 370         if (!fc->no_interrupt) {
 371                 /* Any signal may interrupt this */
 372                 err = wait_event_interruptible(req->waitq,
 373                                         test_bit(FR_FINISHED, &req->flags));
 374                 if (!err)
 375                         return;
 376
 377                 set_bit(FR_INTERRUPTED, &req->flags);
 378                 /* matches barrier in fuse_dev_do_read() */
 379                 smp_mb__after_atomic();
 380                 if (test_bit(FR_SENT, &req->flags))
 381                         queue_interrupt(req);
 382         }
 383
 384         if (!test_bit(FR_FORCE, &req->flags)) {
 385                 /* Only fatal signals may interrupt this */
 386                 err = wait_event_killable(req->waitq,
 387                                         test_bit(FR_FINISHED, &req->flags));
 388                 if (!err)
 389                         return;
 390
 391                 spin_lock(&fiq->lock);
 392                 /* Request is not yet in userspace, bail out */
 393                 if (test_bit(FR_PENDING, &req->flags)) {
 394                         list_del(&req->list);
 395                         spin_unlock(&fiq->lock);
 396                         __fuse_put_request(req);
 397                         req->out.h.error = -EINTR;
 398                         return;
 399                 }
 400                 spin_unlock(&fiq->lock);
 401         }
 402
 403         /*
 404          * Either request is already in userspace, or it was forced.
 405          * Wait it out.
 406          */
 407         wait_event(req->waitq, test_bit(FR_FINISHED, &req->flags));
 408 }
 409
 410 static void __fuse_request_send(struct fuse_req *req)
 411 {
 412         struct fuse_iqueue *fiq = &req->fm->fc->iq;
 413
 414         BUG_ON(test_bit(FR_BACKGROUND, &req->flags));
 415         spin_lock(&fiq->lock);
 416         if (!fiq->connected) {
 417                 spin_unlock(&fiq->lock);
 418                 req->out.h.error = -ENOTCONN;
 419         } else {
 420                 req->in.h.unique = fuse_get_unique(fiq);
 421                 /* acquire extra reference, since request is still needed
 422                    after fuse_request_end() */
 423                 __fuse_get_request(req);
 424                 queue_request_and_unlock(fiq, req);
 425
 426                 request_wait_answer(req);
 427                 /* Pairs with smp_wmb() in fuse_request_end() */
 428                 smp_rmb();
 429         }
 430 }
 431
 432 static void fuse_adjust_compat(struct fuse_conn *fc, struct fuse_args *args)
 433 {
 434         if (fc->minor < 4 && args->opcode == FUSE_STATFS)
 435                 args->out_args[0].size = FUSE_COMPAT_STATFS_SIZE;
 436
 437         if (fc->minor < 9) {
 438                 switch (args->opcode) {
 439                 case FUSE_LOOKUP:
 440                 case FUSE_CREATE:
 441                 case FUSE_MKNOD:
 442                 case FUSE_MKDIR:
 443                 case FUSE_SYMLINK:
 444                 case FUSE_LINK:
 445                         args->out_args[0].size = FUSE_COMPAT_ENTRY_OUT_SIZE;
 446                         break;
 447                 case FUSE_GETATTR:
 448                 case FUSE_SETATTR:
 449                         args->out_args[0].size = FUSE_COMPAT_ATTR_OUT_SIZE;
 450                         break;
 451                 }
 452         }
 453         if (fc->minor < 12) {
 454                 switch (args->opcode) {
 455                 case FUSE_CREATE:
 456                         args->in_args[0].size = sizeof(struct fuse_open_in);
 457                         break;
 458                 case FUSE_MKNOD:
 459                         args->in_args[0].size = FUSE_COMPAT_MKNOD_IN_SIZE;
 460                         break;
 461                 }
 462         }
 463 }
 464
 465 static void fuse_force_creds(struct fuse_req *req)
 466 {
 467         struct fuse_conn *fc = req->fm->fc;
 468
 469         req->in.h.uid = from_kuid_munged(fc->user_ns, current_fsuid());
 470         req->in.h.gid = from_kgid_munged(fc->user_ns, current_fsgid());
 471         req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns);
 472 }
 473
 474 static void fuse_args_to_req(struct fuse_req *req, struct fuse_args *args)
 475 {
 476         req->in.h.opcode = args->opcode;
 477         req->in.h.nodeid = args->nodeid;
 478         req->args = args;
 479         if (args->end)
 480                 __set_bit(FR_ASYNC, &req->flags);
 481 }
 482
 483 ssize_t fuse_simple_request(struct fuse_mount *fm, struct fuse_args *args)
 484 {
 485         struct fuse_conn *fc = fm->fc;
 486         struct fuse_req *req;
 487         ssize_t ret;
 488
 489         if (args->force) {
 490                 atomic_inc(&fc->num_waiting);
 491                 req = fuse_request_alloc(fm, GFP_KERNEL | __GFP_NOFAIL);
 492
 493                 if (!args->nocreds)
 494                         fuse_force_creds(req);
 495
 496                 __set_bit(FR_WAITING, &req->flags);
 497                 __set_bit(FR_FORCE, &req->flags);
 498         } else {
 499                 WARN_ON(args->nocreds);
 500                 req = fuse_get_req(fm, false);
 501                 if (IS_ERR(req))
 502                         return PTR_ERR(req);
 503         }
 504
 505         /* Needs to be done after fuse_get_req() so that fc->minor is valid */
 506         fuse_adjust_compat(fc, args);
 507         fuse_args_to_req(req, args);
 508
 509         if (!args->noreply)
 510                 __set_bit(FR_ISREPLY, &req->flags);
 511         __fuse_request_send(req);
 512         ret = req->out.h.error;
 513         if (!ret && args->out_argvar) {
 514                 BUG_ON(args->out_numargs == 0);
 515                 ret = args->out_args[args->out_numargs - 1].size;
 516         }
 517         fuse_put_request(req);
 518
 519         return ret;
 520 }
 521
 522 static bool fuse_request_queue_background(struct fuse_req *req)
 523 {
 524         struct fuse_mount *fm = req->fm;
 525         struct fuse_conn *fc = fm->fc;
 526         bool queued = false;
 527
 528         WARN_ON(!test_bit(FR_BACKGROUND, &req->flags));
 529         if (!test_bit(FR_WAITING, &req->flags)) {
 530                 __set_bit(FR_WAITING, &req->flags);
 531                 atomic_inc(&fc->num_waiting);
 532         }
 533         __set_bit(FR_ISREPLY, &req->flags);
 534         spin_lock(&fc->bg_lock);
 535         if (likely(fc->connected)) {
 536                 fc->num_background++;
 537                 if (fc->num_background == fc->max_background)
 538                         fc->blocked = 1;
 539                 list_add_tail(&req->list, &fc->bg_queue);
 540                 flush_bg_queue(fc);
 541                 queued = true;
 542         }
 543         spin_unlock(&fc->bg_lock);
 544
 545         return queued;
 546 }
 547
 548 int fuse_simple_background(struct fuse_mount *fm, struct fuse_args *args,
 549                             gfp_t gfp_flags)
 550 {
 551         struct fuse_req *req;
 552
 553         if (args->force) {
 554                 WARN_ON(!args->nocreds);
 555                 req = fuse_request_alloc(fm, gfp_flags);
 556                 if (!req)
 557                         return -ENOMEM;
 558                 __set_bit(FR_BACKGROUND, &req->flags);
 559         } else {
 560                 WARN_ON(args->nocreds);
 561                 req = fuse_get_req(fm, true);
 562                 if (IS_ERR(req))
 563                         return PTR_ERR(req);
 564         }
 565
 566         fuse_args_to_req(req, args);
 567
 568         if (!fuse_request_queue_background(req)) {
 569                 fuse_put_request(req);
 570                 return -ENOTCONN;
 571         }
 572
 573         return 0;
 574 }
 575 EXPORT_SYMBOL_GPL(fuse_simple_background);
 576
 577 static int fuse_simple_notify_reply(struct fuse_mount *fm,
 578                                     struct fuse_args *args, u64 unique)
 579 {
 580         struct fuse_req *req;
 581         struct fuse_iqueue *fiq = &fm->fc->iq;
 582         int err = 0;
 583
 584         req = fuse_get_req(fm, false);
 585         if (IS_ERR(req))
 586                 return PTR_ERR(req);
 587
 588         __clear_bit(FR_ISREPLY, &req->flags);
 589         req->in.h.unique = unique;
 590
 591         fuse_args_to_req(req, args);
 592
 593         spin_lock(&fiq->lock);
 594         if (fiq->connected) {
 595                 queue_request_and_unlock(fiq, req);
 596         } else {
 597                 err = -ENODEV;
 598                 spin_unlock(&fiq->lock);
 599                 fuse_put_request(req);
 600         }
 601
 602         return err;
 603 }
 604
 605 /*
 606  * Lock the request.  Up to the next unlock_request() there mustn't be
 607  * anything that could cause a page-fault.  If the request was already
 608  * aborted bail out.
 609  */
 610 static int lock_request(struct fuse_req *req)
 611 {
 612         int err = 0;
 613         if (req) {
 614                 spin_lock(&req->waitq.lock);
 615                 if (test_bit(FR_ABORTED, &req->flags))
 616                         err = -ENOENT;
 617                 else
 618                         set_bit(FR_LOCKED, &req->flags);
 619                 spin_unlock(&req->waitq.lock);
 620         }
 621         return err;
 622 }
 623
 624 /*
 625  * Unlock request.  If it was aborted while locked, caller is responsible
 626  * for unlocking and ending the request.
 627  */
 628 static int unlock_request(struct fuse_req *req)
 629 {
 630         int err = 0;
 631         if (req) {
 632                 spin_lock(&req->waitq.lock);
 633                 if (test_bit(FR_ABORTED, &req->flags))
 634                         err = -ENOENT;
 635                 else
 636                         clear_bit(FR_LOCKED, &req->flags);
 637                 spin_unlock(&req->waitq.lock);
 638         }
 639         return err;
 640 }
 641
 642 struct fuse_copy_state {
 643         int write;
 644         struct fuse_req *req;
 645         struct iov_iter *iter;
 646         struct pipe_buffer *pipebufs;
 647         struct pipe_buffer *currbuf;
 648         struct pipe_inode_info *pipe;
 649         unsigned long nr_segs;
 650         struct page *pg;
 651         unsigned len;
 652         unsigned offset;
 653         unsigned move_pages:1;
 654 };
 655
 656 static void fuse_copy_init(struct fuse_copy_state *cs, int write,
 657                            struct iov_iter *iter)
 658 {
 659         memset(cs, 0, sizeof(*cs));
 660         cs->write = write;
 661         cs->iter = iter;
 662 }
 663
 664 /* Unmap and put previous page of userspace buffer */
 665 static void fuse_copy_finish(struct fuse_copy_state *cs)
 666 {
 667         if (cs->currbuf) {
 668                 struct pipe_buffer *buf = cs->currbuf;
 669
 670                 if (cs->write)
 671                         buf->len = PAGE_SIZE - cs->len;
 672                 cs->currbuf = NULL;
 673         } else if (cs->pg) {
 674                 if (cs->write) {
 675                         flush_dcache_page(cs->pg);
 676                         set_page_dirty_lock(cs->pg);
 677                 }
 678                 put_page(cs->pg);
 679         }
 680         cs->pg = NULL;
 681 }
 682
 683 /*
 684  * Get another pagefull of userspace buffer, and map it to kernel
 685  * address space, and lock request
 686  */
 687 static int fuse_copy_fill(struct fuse_copy_state *cs)
 688 {
 689         struct page *page;
 690         int err;
 691
 692         err = unlock_request(cs->req);
 693         if (err)
 694                 return err;
 695
 696         fuse_copy_finish(cs);
 697         if (cs->pipebufs) {
 698                 struct pipe_buffer *buf = cs->pipebufs;
 699
 700                 if (!cs->write) {
 701                         err = pipe_buf_confirm(cs->pipe, buf);
 702                         if (err)
 703                                 return err;
 704
 705                         BUG_ON(!cs->nr_segs);
 706                         cs->currbuf = buf;
 707                         cs->pg = buf->page;
 708                         cs->offset = buf->offset;
 709                         cs->len = buf->len;
 710                         cs->pipebufs++;
 711                         cs->nr_segs--;
 712                 } else {
 713                         if (cs->nr_segs >= cs->pipe->max_usage)
 714                                 return -EIO;
 715
 716                         page = alloc_page(GFP_HIGHUSER);
 717                         if (!page)
 718                                 return -ENOMEM;
 719
 720                         buf->page = page;
 721                         buf->offset = 0;
 722                         buf->len = 0;
 723
 724                         cs->currbuf = buf;
 725                         cs->pg = page;
 726                         cs->offset = 0;
 727                         cs->len = PAGE_SIZE;
 728                         cs->pipebufs++;
 729                         cs->nr_segs++;
 730                 }
 731         } else {
 732                 size_t off;
 733                 err = iov_iter_get_pages2(cs->iter, &page, PAGE_SIZE, 1, &off);
 734                 if (err < 0)
 735                         return err;
 736                 BUG_ON(!err);
 737                 cs->len = err;
 738                 cs->offset = off;
 739                 cs->pg = page;
 740         }
 741
 742         return lock_request(cs->req);
 743 }
 744
 745 /* Do as much copy to/from userspace buffer as we can */
 746 static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
 747 {
 748         unsigned ncpy = min(*size, cs->len);
 749         if (val) {
 750                 void *pgaddr = kmap_local_page(cs->pg);
 751                 void *buf = pgaddr + cs->offset;
 752
 753                 if (cs->write)
 754                         memcpy(buf, *val, ncpy);
 755                 else
 756                         memcpy(*val, buf, ncpy);
 757
 758                 kunmap_local(pgaddr);
 759                 *val += ncpy;
 760         }
 761         *size -= ncpy;
 762         cs->len -= ncpy;
 763         cs->offset += ncpy;
 764         return ncpy;
 765 }
 766
 767 static int fuse_check_page(struct page *page)
 768 {
 769         if (page_mapcount(page) ||
 770             page->mapping != NULL ||
 771             (page->flags & PAGE_FLAGS_CHECK_AT_PREP &
 772              ~(1 << PG_locked |
 773                1 << PG_referenced |
 774                1 << PG_uptodate |
 775                1 << PG_lru |
 776                1 << PG_active |
 777                1 << PG_workingset |
 778                1 << PG_reclaim |
 779                1 << PG_waiters |
 780                LRU_GEN_MASK | LRU_REFS_MASK))) {
 781                 dump_page(page, "fuse: trying to steal weird page");
 782                 return 1;
 783         }
 784         return 0;
 785 }
 786
 787 static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
 788 {
 789         int err;
 790         struct page *oldpage = *pagep;
 791         struct page *newpage;
 792         struct pipe_buffer *buf = cs->pipebufs;
 793
 794         get_page(oldpage);
 795         err = unlock_request(cs->req);
 796         if (err)
 797                 goto out_put_old;
 798
 799         fuse_copy_finish(cs);
 800
 801         err = pipe_buf_confirm(cs->pipe, buf);
 802         if (err)
 803                 goto out_put_old;
 804
 805         BUG_ON(!cs->nr_segs);
 806         cs->currbuf = buf;
 807         cs->len = buf->len;
 808         cs->pipebufs++;
 809         cs->nr_segs--;
 810
 811         if (cs->len != PAGE_SIZE)
 812                 goto out_fallback;
 813
 814         if (!pipe_buf_try_steal(cs->pipe, buf))
 815                 goto out_fallback;
 816
 817         newpage = buf->page;
 818
 819         if (!PageUptodate(newpage))
 820                 SetPageUptodate(newpage);
 821
 822         ClearPageMappedToDisk(newpage);
 823
 824         if (fuse_check_page(newpage) != 0)
 825                 goto out_fallback_unlock;
 826
 827         /*
 828          * This is a new and locked page, it shouldn't be mapped or
 829          * have any special flags on it
 830          */
 831         if (WARN_ON(page_mapped(oldpage)))
 832                 goto out_fallback_unlock;
 833         if (WARN_ON(page_has_private(oldpage)))
 834                 goto out_fallback_unlock;
 835         if (WARN_ON(PageDirty(oldpage) || PageWriteback(oldpage)))
 836                 goto out_fallback_unlock;
 837         if (WARN_ON(PageMlocked(oldpage)))
 838                 goto out_fallback_unlock;
 839
 840         replace_page_cache_page(oldpage, newpage);
 841
 842         get_page(newpage);
 843
 844         if (!(buf->flags & PIPE_BUF_FLAG_LRU))
 845                 lru_cache_add(newpage);
 846
 847         /*
 848          * Release while we have extra ref on stolen page.  Otherwise
 849          * anon_pipe_buf_release() might think the page can be reused.
 850          */
 851         pipe_buf_release(cs->pipe, buf);
 852
 853         err = 0;
 854         spin_lock(&cs->req->waitq.lock);
 855         if (test_bit(FR_ABORTED, &cs->req->flags))
 856                 err = -ENOENT;
 857         else
 858                 *pagep = newpage;
 859         spin_unlock(&cs->req->waitq.lock);
 860
 861         if (err) {
 862                 unlock_page(newpage);
 863                 put_page(newpage);
 864                 goto out_put_old;
 865         }
 866
 867         unlock_page(oldpage);
 868         /* Drop ref for ap->pages[] array */
 869         put_page(oldpage);
 870         cs->len = 0;
 871
 872         err = 0;
 873 out_put_old:
 874         /* Drop ref obtained in this function */
 875         put_page(oldpage);
 876         return err;
 877
 878 out_fallback_unlock:
 879         unlock_page(newpage);
 880 out_fallback:
 881         cs->pg = buf->page;
 882         cs->offset = buf->offset;
 883
 884         err = lock_request(cs->req);
 885         if (!err)
 886                 err = 1;
 887
 888         goto out_put_old;
 889 }
 890
 891 static int fuse_ref_page(struct fuse_copy_state *cs, struct page *page,
 892                          unsigned offset, unsigned count)
 893 {
 894         struct pipe_buffer *buf;
 895         int err;
 896
 897         if (cs->nr_segs >= cs->pipe->max_usage)
 898                 return -EIO;
 899
 900         get_page(page);
 901         err = unlock_request(cs->req);
 902         if (err) {
 903                 put_page(page);
 904                 return err;
 905         }
 906
 907         fuse_copy_finish(cs);
 908
 909         buf = cs->pipebufs;
 910         buf->page = page;
 911         buf->offset = offset;
 912         buf->len = count;
 913
 914         cs->pipebufs++;
 915         cs->nr_segs++;
 916         cs->len = 0;
 917
 918         return 0;
 919 }
 920
 921 /*
 922  * Copy a page in the request to/from the userspace buffer.  Must be
 923  * done atomically
 924  */
 925 static int fuse_copy_page(struct fuse_copy_state *cs, struct page **pagep,
 926                           unsigned offset, unsigned count, int zeroing)
 927 {
 928         int err;
 929         struct page *page = *pagep;
 930
 931         if (page && zeroing && count < PAGE_SIZE)
 932                 clear_highpage(page);
 933
 934         while (count) {
 935                 if (cs->write && cs->pipebufs && page) {
 936                         /*
 937                          * Can't control lifetime of pipe buffers, so always
 938                          * copy user pages.
 939                          */
 940                         if (cs->req->args->user_pages) {
 941                                 err = fuse_copy_fill(cs);
 942                                 if (err)
 943                                         return err;
 944                         } else {
 945                                 return fuse_ref_page(cs, page, offset, count);
 946                         }
 947                 } else if (!cs->len) {
 948                         if (cs->move_pages && page &&
 949                             offset == 0 && count == PAGE_SIZE) {
 950                                 err = fuse_try_move_page(cs, pagep);
 951                                 if (err <= 0)
 952                                         return err;
 953                         } else {
 954                                 err = fuse_copy_fill(cs);
 955                                 if (err)
 956                                         return err;
 957                         }
 958                 }
 959                 if (page) {
 960                         void *mapaddr = kmap_local_page(page);
 961                         void *buf = mapaddr + offset;
 962                         offset += fuse_copy_do(cs, &buf, &count);
 963                         kunmap_local(mapaddr);
 964                 } else
 965                         offset += fuse_copy_do(cs, NULL, &count);
 966         }
 967         if (page && !cs->write)
 968                 flush_dcache_page(page);
 969         return 0;
 970 }
 971
 972 /* Copy pages in the request to/from userspace buffer */
 973 static int fuse_copy_pages(struct fuse_copy_state *cs, unsigned nbytes,
 974                            int zeroing)
 975 {
 976         unsigned i;
 977         struct fuse_req *req = cs->req;
 978         struct fuse_args_pages *ap = container_of(req->args, typeof(*ap), args);
 979
 980
 981         for (i = 0; i < ap->num_pages && (nbytes || zeroing); i++) {
 982                 int err;
 983                 unsigned int offset = ap->descs[i].offset;
 984                 unsigned int count = min(nbytes, ap->descs[i].length);
 985
 986                 err = fuse_copy_page(cs, &ap->pages[i], offset, count, zeroing);
 987                 if (err)
 988                         return err;
 989
 990                 nbytes -= count;
 991         }
 992         return 0;
 993 }
 994
 995 /* Copy a single argument in the request to/from userspace buffer */
 996 static int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned size)
 997 {
 998         while (size) {
 999                 if (!cs->len) {
1000                         int err = fuse_copy_fill(cs);
1001                         if (err)
1002                                 return err;
1003                 }
1004                 fuse_copy_do(cs, &val, &size);
1005         }
1006         return 0;
1007 }
1008
1009 /* Copy request arguments to/from userspace buffer */
1010 static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs,
1011                           unsigned argpages, struct fuse_arg *args,
1012                           int zeroing)
1013 {
1014         int err = 0;
1015         unsigned i;
1016
1017         for (i = 0; !err && i < numargs; i++)  {
1018                 struct fuse_arg *arg = &args[i];
1019                 if (i == numargs - 1 && argpages)
1020                         err = fuse_copy_pages(cs, arg->size, zeroing);
1021                 else
1022                         err = fuse_copy_one(cs, arg->value, arg->size);
1023         }
1024         return err;
1025 }
1026
1027 static int forget_pending(struct fuse_iqueue *fiq)
1028 {
1029         return fiq->forget_list_head.next != NULL;
1030 }
1031
1032 static int request_pending(struct fuse_iqueue *fiq)
1033 {
1034         return !list_empty(&fiq->pending) || !list_empty(&fiq->interrupts) ||
1035                 forget_pending(fiq);
1036 }
1037
1038 /*
1039  * Transfer an interrupt request to userspace
1040  *
1041  * Unlike other requests this is assembled on demand, without a need
1042  * to allocate a separate fuse_req structure.
1043  *
1044  * Called with fiq->lock held, releases it
1045  */
1046 static int fuse_read_interrupt(struct fuse_iqueue *fiq,
1047                                struct fuse_copy_state *cs,
1048                                size_t nbytes, struct fuse_req *req)
1049 __releases(fiq->lock)
1050 {
1051         struct fuse_in_header ih;
1052         struct fuse_interrupt_in arg;
1053         unsigned reqsize = sizeof(ih) + sizeof(arg);
1054         int err;
1055
1056         list_del_init(&req->intr_entry);
1057         memset(&ih, 0, sizeof(ih));
1058         memset(&arg, 0, sizeof(arg));
1059         ih.len = reqsize;
1060         ih.opcode = FUSE_INTERRUPT;
1061         ih.unique = (req->in.h.unique | FUSE_INT_REQ_BIT);
1062         arg.unique = req->in.h.unique;
1063
1064         spin_unlock(&fiq->lock);
1065         if (nbytes < reqsize)
1066                 return -EINVAL;
1067
1068         err = fuse_copy_one(cs, &ih, sizeof(ih));
1069         if (!err)
1070                 err = fuse_copy_one(cs, &arg, sizeof(arg));
1071         fuse_copy_finish(cs);
1072
1073         return err ? err : reqsize;
1074 }
1075
1076 struct fuse_forget_link *fuse_dequeue_forget(struct fuse_iqueue *fiq,
1077                                              unsigned int max,
1078                                              unsigned int *countp)
1079 {
1080         struct fuse_forget_link *head = fiq->forget_list_head.next;
1081         struct fuse_forget_link **newhead = &head;
1082         unsigned count;
1083
1084         for (count = 0; *newhead != NULL && count < max; count++)
1085                 newhead = &(*newhead)->next;
1086
1087         fiq->forget_list_head.next = *newhead;
1088         *newhead = NULL;
1089         if (fiq->forget_list_head.next == NULL)
1090                 fiq->forget_list_tail = &fiq->forget_list_head;
1091
1092         if (countp != NULL)
1093                 *countp = count;
1094
1095         return head;
1096 }
1097 EXPORT_SYMBOL(fuse_dequeue_forget);
1098
1099 static int fuse_read_single_forget(struct fuse_iqueue *fiq,
1100                                    struct fuse_copy_state *cs,
1101                                    size_t nbytes)
1102 __releases(fiq->lock)
1103 {
1104         int err;
1105         struct fuse_forget_link *forget = fuse_dequeue_forget(fiq, 1, NULL);
1106         struct fuse_forget_in arg = {
1107                 .nlookup = forget->forget_one.nlookup,
1108         };
1109         struct fuse_in_header ih = {
1110                 .opcode = FUSE_FORGET,
1111                 .nodeid = forget->forget_one.nodeid,
1112                 .unique = fuse_get_unique(fiq),
1113                 .len = sizeof(ih) + sizeof(arg),
1114         };
1115
1116         spin_unlock(&fiq->lock);
1117         kfree(forget);
1118         if (nbytes < ih.len)
1119                 return -EINVAL;
1120
1121         err = fuse_copy_one(cs, &ih, sizeof(ih));
1122         if (!err)
1123                 err = fuse_copy_one(cs, &arg, sizeof(arg));
1124         fuse_copy_finish(cs);
1125
1126         if (err)
1127                 return err;
1128
1129         return ih.len;
1130 }
1131
1132 static int fuse_read_batch_forget(struct fuse_iqueue *fiq,
1133                                    struct fuse_copy_state *cs, size_t nbytes)
1134 __releases(fiq->lock)
1135 {
1136         int err;
1137         unsigned max_forgets;
1138         unsigned count;
1139         struct fuse_forget_link *head;
1140         struct fuse_batch_forget_in arg = { .count = 0 };
1141         struct fuse_in_header ih = {
1142                 .opcode = FUSE_BATCH_FORGET,
1143                 .unique = fuse_get_unique(fiq),
1144                 .len = sizeof(ih) + sizeof(arg),
1145         };
1146
1147         if (nbytes < ih.len) {
1148                 spin_unlock(&fiq->lock);
1149                 return -EINVAL;
1150         }
1151
1152         max_forgets = (nbytes - ih.len) / sizeof(struct fuse_forget_one);
1153         head = fuse_dequeue_forget(fiq, max_forgets, &count);
1154         spin_unlock(&fiq->lock);
1155
1156         arg.count = count;
1157         ih.len += count * sizeof(struct fuse_forget_one);
1158         err = fuse_copy_one(cs, &ih, sizeof(ih));
1159         if (!err)
1160                 err = fuse_copy_one(cs, &arg, sizeof(arg));
1161
1162         while (head) {
1163                 struct fuse_forget_link *forget = head;
1164
1165                 if (!err) {
1166                         err = fuse_copy_one(cs, &forget->forget_one,
1167                                             sizeof(forget->forget_one));
1168                 }
1169                 head = forget->next;
1170                 kfree(forget);
1171         }
1172
1173         fuse_copy_finish(cs);
1174
1175         if (err)
1176                 return err;
1177
1178         return ih.len;
1179 }
1180
1181 static int fuse_read_forget(struct fuse_conn *fc, struct fuse_iqueue *fiq,
1182                             struct fuse_copy_state *cs,
1183                             size_t nbytes)
1184 __releases(fiq->lock)
1185 {
1186         if (fc->minor < 16 || fiq->forget_list_head.next->next == NULL)
1187                 return fuse_read_single_forget(fiq, cs, nbytes);
1188         else
1189                 return fuse_read_batch_forget(fiq, cs, nbytes);
1190 }
1191
1192 /*
1193  * Read a single request into the userspace filesystem's buffer.  This
1194  * function waits until a request is available, then removes it from
1195  * the pending list and copies request data to userspace buffer.  If
1196  * no reply is needed (FORGET) or request has been aborted or there
1197  * was an error during the copying then it's finished by calling
1198  * fuse_request_end().  Otherwise add it to the processing list, and set
1199  * the 'sent' flag.
1200  */
1201 static ssize_t fuse_dev_do_read(struct fuse_dev *fud, struct file *file,
1202                                 struct fuse_copy_state *cs, size_t nbytes)
1203 {
1204         ssize_t err;
1205         struct fuse_conn *fc = fud->fc;
1206         struct fuse_iqueue *fiq = &fc->iq;
1207         struct fuse_pqueue *fpq = &fud->pq;
1208         struct fuse_req *req;
1209         struct fuse_args *args;
1210         unsigned reqsize;
1211         unsigned int hash;
1212
1213         /*
1214          * Require sane minimum read buffer - that has capacity for fixed part
1215          * of any request header + negotiated max_write room for data.
1216          *
1217          * Historically libfuse reserves 4K for fixed header room, but e.g.
1218          * GlusterFS reserves only 80 bytes
1219          *
1220          *      = `sizeof(fuse_in_header) + sizeof(fuse_write_in)`
1221          *
1222          * which is the absolute minimum any sane filesystem should be using
1223          * for header room.
1224          */
1225         if (nbytes < max_t(size_t, FUSE_MIN_READ_BUFFER,
1226                            sizeof(struct fuse_in_header) +
1227                            sizeof(struct fuse_write_in) +
1228                            fc->max_write))
1229                 return -EINVAL;
1230
1231  restart:
1232         for (;;) {
1233                 spin_lock(&fiq->lock);
1234                 if (!fiq->connected || request_pending(fiq))
1235                         break;
1236                 spin_unlock(&fiq->lock);
1237
1238                 if (file->f_flags & O_NONBLOCK)
1239                         return -EAGAIN;
1240                 err = wait_event_interruptible_exclusive(fiq->waitq,
1241                                 !fiq->connected || request_pending(fiq));
1242                 if (err)
1243                         return err;
1244         }
1245
1246         if (!fiq->connected) {
1247                 err = fc->aborted ? -ECONNABORTED : -ENODEV;
1248                 goto err_unlock;
1249         }
1250
1251         if (!list_empty(&fiq->interrupts)) {
1252                 req = list_entry(fiq->interrupts.next, struct fuse_req,
1253                                  intr_entry);
1254                 return fuse_read_interrupt(fiq, cs, nbytes, req);
1255         }
1256
1257         if (forget_pending(fiq)) {
1258                 if (list_empty(&fiq->pending) || fiq->forget_batch-- > 0)
1259                         return fuse_read_forget(fc, fiq, cs, nbytes);
1260
1261                 if (fiq->forget_batch <= -8)
1262                         fiq->forget_batch = 16;
1263         }
1264
1265         req = list_entry(fiq->pending.next, struct fuse_req, list);
1266         clear_bit(FR_PENDING, &req->flags);
1267         list_del_init(&req->list);
1268         spin_unlock(&fiq->lock);
1269
1270         args = req->args;
1271         reqsize = req->in.h.len;
1272
1273         /* If request is too large, reply with an error and restart the read */
1274         if (nbytes < reqsize) {
1275                 req->out.h.error = -EIO;
1276                 /* SETXATTR is special, since it may contain too large data */
1277                 if (args->opcode == FUSE_SETXATTR)
1278                         req->out.h.error = -E2BIG;
1279                 fuse_request_end(req);
1280                 goto restart;
1281         }
1282         spin_lock(&fpq->lock);
1283         /*
1284          *  Must not put request on fpq->io queue after having been shut down by
1285          *  fuse_abort_conn()
1286          */
1287         if (!fpq->connected) {
1288                 req->out.h.error = err = -ECONNABORTED;
1289                 goto out_end;
1290
1291         }
1292         list_add(&req->list, &fpq->io);
1293         spin_unlock(&fpq->lock);
1294         cs->req = req;
1295         err = fuse_copy_one(cs, &req->in.h, sizeof(req->in.h));
1296         if (!err)
1297                 err = fuse_copy_args(cs, args->in_numargs, args->in_pages,
1298                                      (struct fuse_arg *) args->in_args, 0);
1299         fuse_copy_finish(cs);
1300         spin_lock(&fpq->lock);
1301         clear_bit(FR_LOCKED, &req->flags);
1302         if (!fpq->connected) {
1303                 err = fc->aborted ? -ECONNABORTED : -ENODEV;
1304                 goto out_end;
1305         }
1306         if (err) {
1307                 req->out.h.error = -EIO;
1308                 goto out_end;
1309         }
1310         if (!test_bit(FR_ISREPLY, &req->flags)) {
1311                 err = reqsize;
1312                 goto out_end;
1313         }
1314         hash = fuse_req_hash(req->in.h.unique);
1315         list_move_tail(&req->list, &fpq->processing[hash]);
1316         __fuse_get_request(req);
1317         set_bit(FR_SENT, &req->flags);
1318         spin_unlock(&fpq->lock);
1319         /* matches barrier in request_wait_answer() */
1320         smp_mb__after_atomic();
1321         if (test_bit(FR_INTERRUPTED, &req->flags))
1322                 queue_interrupt(req);
1323         fuse_put_request(req);
1324
1325         return reqsize;
1326
1327 out_end:
1328         if (!test_bit(FR_PRIVATE, &req->flags))
1329                 list_del_init(&req->list);
1330         spin_unlock(&fpq->lock);
1331         fuse_request_end(req);
1332         return err;
1333
1334  err_unlock:
1335         spin_unlock(&fiq->lock);
1336         return err;
1337 }
1338
1339 static int fuse_dev_open(struct inode *inode, struct file *file)
1340 {
1341         /*
1342          * The fuse device's file's private_data is used to hold
1343          * the fuse_conn(ection) when it is mounted, and is used to
1344          * keep track of whether the file has been mounted already.
1345          */
1346         file->private_data = NULL;
1347         return 0;
1348 }
1349
1350 static ssize_t fuse_dev_read(struct kiocb *iocb, struct iov_iter *to)
1351 {
1352         struct fuse_copy_state cs;
1353         struct file *file = iocb->ki_filp;
1354         struct fuse_dev *fud = fuse_get_dev(file);
1355
1356         if (!fud)
1357                 return -EPERM;
1358
1359         if (!user_backed_iter(to))
1360                 return -EINVAL;
1361
1362         fuse_copy_init(&cs, 1, to);
1363
1364         return fuse_dev_do_read(fud, file, &cs, iov_iter_count(to));
1365 }
1366
1367 static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
1368                                     struct pipe_inode_info *pipe,
1369                                     size_t len, unsigned int flags)
1370 {
1371         int total, ret;
1372         int page_nr = 0;
1373         struct pipe_buffer *bufs;
1374         struct fuse_copy_state cs;
1375         struct fuse_dev *fud = fuse_get_dev(in);
1376
1377         if (!fud)
1378                 return -EPERM;
1379
1380         bufs = kvmalloc_array(pipe->max_usage, sizeof(struct pipe_buffer),
1381                               GFP_KERNEL);
1382         if (!bufs)
1383                 return -ENOMEM;
1384
1385         fuse_copy_init(&cs, 1, NULL);
1386         cs.pipebufs = bufs;
1387         cs.pipe = pipe;
1388         ret = fuse_dev_do_read(fud, in, &cs, len);
1389         if (ret < 0)
1390                 goto out;
1391
1392         if (pipe_occupancy(pipe->head, pipe->tail) + cs.nr_segs > pipe->max_usage) {
1393                 ret = -EIO;
1394                 goto out;
1395         }
1396
1397         for (ret = total = 0; page_nr < cs.nr_segs; total += ret) {
1398                 /*
1399                  * Need to be careful about this.  Having buf->ops in module
1400                  * code can Oops if the buffer persists after module unload.
1401                  */
1402                 bufs[page_nr].ops = &nosteal_pipe_buf_ops;
1403                 bufs[page_nr].flags = 0;
1404                 ret = add_to_pipe(pipe, &bufs[page_nr++]);
1405                 if (unlikely(ret < 0))
1406                         break;
1407         }
1408         if (total)
1409                 ret = total;
1410 out:
1411         for (; page_nr < cs.nr_segs; page_nr++)
1412                 put_page(bufs[page_nr].page);
1413
1414         kvfree(bufs);
1415         return ret;
1416 }
1417
1418 static int fuse_notify_poll(struct fuse_conn *fc, unsigned int size,
1419                             struct fuse_copy_state *cs)
1420 {
1421         struct fuse_notify_poll_wakeup_out outarg;
1422         int err = -EINVAL;
1423
1424         if (size != sizeof(outarg))
1425                 goto err;
1426
1427         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1428         if (err)
1429                 goto err;
1430
1431         fuse_copy_finish(cs);
1432         return fuse_notify_poll_wakeup(fc, &outarg);
1433
1434 err:
1435         fuse_copy_finish(cs);
1436         return err;
1437 }
1438
1439 static int fuse_notify_inval_inode(struct fuse_conn *fc, unsigned int size,
1440                                    struct fuse_copy_state *cs)
1441 {
1442         struct fuse_notify_inval_inode_out outarg;
1443         int err = -EINVAL;
1444
1445         if (size != sizeof(outarg))
1446                 goto err;
1447
1448         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1449         if (err)
1450                 goto err;
1451         fuse_copy_finish(cs);
1452
1453         down_read(&fc->killsb);
1454         err = fuse_reverse_inval_inode(fc, outarg.ino,
1455                                        outarg.off, outarg.len);
1456         up_read(&fc->killsb);
1457         return err;
1458
1459 err:
1460         fuse_copy_finish(cs);
1461         return err;
1462 }
1463
1464 static int fuse_notify_inval_entry(struct fuse_conn *fc, unsigned int size,
1465                                    struct fuse_copy_state *cs)
1466 {
1467         struct fuse_notify_inval_entry_out outarg;
1468         int err = -ENOMEM;
1469         char *buf;
1470         struct qstr name;
1471
1472         buf = kzalloc(FUSE_NAME_MAX + 1, GFP_KERNEL);
1473         if (!buf)
1474                 goto err;
1475
1476         err = -EINVAL;
1477         if (size < sizeof(outarg))
1478                 goto err;
1479
1480         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1481         if (err)
1482                 goto err;
1483
1484         err = -ENAMETOOLONG;
1485         if (outarg.namelen > FUSE_NAME_MAX)
1486                 goto err;
1487
1488         err = -EINVAL;
1489         if (size != sizeof(outarg) + outarg.namelen + 1)
1490                 goto err;
1491
1492         name.name = buf;
1493         name.len = outarg.namelen;
1494         err = fuse_copy_one(cs, buf, outarg.namelen + 1);
1495         if (err)
1496                 goto err;
1497         fuse_copy_finish(cs);
1498         buf[outarg.namelen] = 0;
1499
1500         down_read(&fc->killsb);
1501         err = fuse_reverse_inval_entry(fc, outarg.parent, 0, &name);
1502         up_read(&fc->killsb);
1503         kfree(buf);
1504         return err;
1505
1506 err:
1507         kfree(buf);
1508         fuse_copy_finish(cs);
1509         return err;
1510 }
1511
1512 static int fuse_notify_delete(struct fuse_conn *fc, unsigned int size,
1513                               struct fuse_copy_state *cs)
1514 {
1515         struct fuse_notify_delete_out outarg;
1516         int err = -ENOMEM;
1517         char *buf;
1518         struct qstr name;
1519
1520         buf = kzalloc(FUSE_NAME_MAX + 1, GFP_KERNEL);
1521         if (!buf)
1522                 goto err;
1523
1524         err = -EINVAL;
1525         if (size < sizeof(outarg))
1526                 goto err;
1527
1528         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1529         if (err)
1530                 goto err;
1531
1532         err = -ENAMETOOLONG;
1533         if (outarg.namelen > FUSE_NAME_MAX)
1534                 goto err;
1535
1536         err = -EINVAL;
1537         if (size != sizeof(outarg) + outarg.namelen + 1)
1538                 goto err;
1539
1540         name.name = buf;
1541         name.len = outarg.namelen;
1542         err = fuse_copy_one(cs, buf, outarg.namelen + 1);
1543         if (err)
1544                 goto err;
1545         fuse_copy_finish(cs);
1546         buf[outarg.namelen] = 0;
1547
1548         down_read(&fc->killsb);
1549         err = fuse_reverse_inval_entry(fc, outarg.parent, outarg.child, &name);
1550         up_read(&fc->killsb);
1551         kfree(buf);
1552         return err;
1553
1554 err:
1555         kfree(buf);
1556         fuse_copy_finish(cs);
1557         return err;
1558 }
1559
1560 static int fuse_notify_store(struct fuse_conn *fc, unsigned int size,
1561                              struct fuse_copy_state *cs)
1562 {
1563         struct fuse_notify_store_out outarg;
1564         struct inode *inode;
1565         struct address_space *mapping;
1566         u64 nodeid;
1567         int err;
1568         pgoff_t index;
1569         unsigned int offset;
1570         unsigned int num;
1571         loff_t file_size;
1572         loff_t end;
1573
1574         err = -EINVAL;
1575         if (size < sizeof(outarg))
1576                 goto out_finish;
1577
1578         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1579         if (err)
1580                 goto out_finish;
1581
1582         err = -EINVAL;
1583         if (size - sizeof(outarg) != outarg.size)
1584                 goto out_finish;
1585
1586         nodeid = outarg.nodeid;
1587
1588         down_read(&fc->killsb);
1589
1590         err = -ENOENT;
1591         inode = fuse_ilookup(fc, nodeid,  NULL);
1592         if (!inode)
1593                 goto out_up_killsb;
1594
1595         mapping = inode->i_mapping;
1596         index = outarg.offset >> PAGE_SHIFT;
1597         offset = outarg.offset & ~PAGE_MASK;
1598         file_size = i_size_read(inode);
1599         end = outarg.offset + outarg.size;
1600         if (end > file_size) {
1601                 file_size = end;
1602                 fuse_write_update_attr(inode, file_size, outarg.size);
1603         }
1604
1605         num = outarg.size;
1606         while (num) {
1607                 struct page *page;
1608                 unsigned int this_num;
1609
1610                 err = -ENOMEM;
1611                 page = find_or_create_page(mapping, index,
1612                                            mapping_gfp_mask(mapping));
1613                 if (!page)
1614                         goto out_iput;
1615
1616                 this_num = min_t(unsigned, num, PAGE_SIZE - offset);
1617                 err = fuse_copy_page(cs, &page, offset, this_num, 0);
1618                 if (!err && offset == 0 &&
1619                     (this_num == PAGE_SIZE || file_size == end))
1620                         SetPageUptodate(page);
1621                 unlock_page(page);
1622                 put_page(page);
1623
1624                 if (err)
1625                         goto out_iput;
1626
1627                 num -= this_num;
1628                 offset = 0;
1629                 index++;
1630         }
1631
1632         err = 0;
1633
1634 out_iput:
1635         iput(inode);
1636 out_up_killsb:
1637         up_read(&fc->killsb);
1638 out_finish:
1639         fuse_copy_finish(cs);
1640         return err;
1641 }
1642
1643 struct fuse_retrieve_args {
1644         struct fuse_args_pages ap;
1645         struct fuse_notify_retrieve_in inarg;
1646 };
1647
1648 static void fuse_retrieve_end(struct fuse_mount *fm, struct fuse_args *args,
1649                               int error)
1650 {
1651         struct fuse_retrieve_args *ra =
1652                 container_of(args, typeof(*ra), ap.args);
1653
1654         release_pages(ra->ap.pages, ra->ap.num_pages);
1655         kfree(ra);
1656 }
1657
1658 static int fuse_retrieve(struct fuse_mount *fm, struct inode *inode,
1659                          struct fuse_notify_retrieve_out *outarg)
1660 {
1661         int err;
1662         struct address_space *mapping = inode->i_mapping;
1663         pgoff_t index;
1664         loff_t file_size;
1665         unsigned int num;
1666         unsigned int offset;
1667         size_t total_len = 0;
1668         unsigned int num_pages;
1669         struct fuse_conn *fc = fm->fc;
1670         struct fuse_retrieve_args *ra;
1671         size_t args_size = sizeof(*ra);
1672         struct fuse_args_pages *ap;
1673         struct fuse_args *args;
1674
1675         offset = outarg->offset & ~PAGE_MASK;
1676         file_size = i_size_read(inode);
1677
1678         num = min(outarg->size, fc->max_write);
1679         if (outarg->offset > file_size)
1680                 num = 0;
1681         else if (outarg->offset + num > file_size)
1682                 num = file_size - outarg->offset;
1683
1684         num_pages = (num + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
1685         num_pages = min(num_pages, fc->max_pages);
1686
1687         args_size += num_pages * (sizeof(ap->pages[0]) + sizeof(ap->descs[0]));
1688
1689         ra = kzalloc(args_size, GFP_KERNEL);
1690         if (!ra)
1691                 return -ENOMEM;
1692
1693         ap = &ra->ap;
1694         ap->pages = (void *) (ra + 1);
1695         ap->descs = (void *) (ap->pages + num_pages);
1696
1697         args = &ap->args;
1698         args->nodeid = outarg->nodeid;
1699         args->opcode = FUSE_NOTIFY_REPLY;
1700         args->in_numargs = 2;
1701         args->in_pages = true;
1702         args->end = fuse_retrieve_end;
1703
1704         index = outarg->offset >> PAGE_SHIFT;
1705
1706         while (num && ap->num_pages < num_pages) {
1707                 struct page *page;
1708                 unsigned int this_num;
1709
1710                 page = find_get_page(mapping, index);
1711                 if (!page)
1712                         break;
1713
1714                 this_num = min_t(unsigned, num, PAGE_SIZE - offset);
1715                 ap->pages[ap->num_pages] = page;
1716                 ap->descs[ap->num_pages].offset = offset;
1717                 ap->descs[ap->num_pages].length = this_num;
1718                 ap->num_pages++;
1719
1720                 offset = 0;
1721                 num -= this_num;
1722                 total_len += this_num;
1723                 index++;
1724         }
1725         ra->inarg.offset = outarg->offset;
1726         ra->inarg.size = total_len;
1727         args->in_args[0].size = sizeof(ra->inarg);
1728         args->in_args[0].value = &ra->inarg;
1729         args->in_args[1].size = total_len;
1730
1731         err = fuse_simple_notify_reply(fm, args, outarg->notify_unique);
1732         if (err)
1733                 fuse_retrieve_end(fm, args, err);
1734
1735         return err;
1736 }
1737
1738 static int fuse_notify_retrieve(struct fuse_conn *fc, unsigned int size,
1739                                 struct fuse_copy_state *cs)
1740 {
1741         struct fuse_notify_retrieve_out outarg;
1742         struct fuse_mount *fm;
1743         struct inode *inode;
1744         u64 nodeid;
1745         int err;
1746
1747         err = -EINVAL;
1748         if (size != sizeof(outarg))
1749                 goto copy_finish;
1750
1751         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1752         if (err)
1753                 goto copy_finish;
1754
1755         fuse_copy_finish(cs);
1756
1757         down_read(&fc->killsb);
1758         err = -ENOENT;
1759         nodeid = outarg.nodeid;
1760
1761         inode = fuse_ilookup(fc, nodeid, &fm);
1762         if (inode) {
1763                 err = fuse_retrieve(fm, inode, &outarg);
1764                 iput(inode);
1765         }
1766         up_read(&fc->killsb);
1767
1768         return err;
1769
1770 copy_finish:
1771         fuse_copy_finish(cs);
1772         return err;
1773 }
1774
1775 static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
1776                        unsigned int size, struct fuse_copy_state *cs)
1777 {
1778         /* Don't try to move pages (yet) */
1779         cs->move_pages = 0;
1780
1781         switch (code) {
1782         case FUSE_NOTIFY_POLL:
1783                 return fuse_notify_poll(fc, size, cs);
1784
1785         case FUSE_NOTIFY_INVAL_INODE:
1786                 return fuse_notify_inval_inode(fc, size, cs);
1787
1788         case FUSE_NOTIFY_INVAL_ENTRY:
1789                 return fuse_notify_inval_entry(fc, size, cs);
1790
1791         case FUSE_NOTIFY_STORE:
1792                 return fuse_notify_store(fc, size, cs);
1793
1794         case FUSE_NOTIFY_RETRIEVE:
1795                 return fuse_notify_retrieve(fc, size, cs);
1796
1797         case FUSE_NOTIFY_DELETE:
1798                 return fuse_notify_delete(fc, size, cs);
1799
1800         default:
1801                 fuse_copy_finish(cs);
1802                 return -EINVAL;
1803         }
1804 }
1805
1806 /* Look up request on processing list by unique ID */
1807 static struct fuse_req *request_find(struct fuse_pqueue *fpq, u64 unique)
1808 {
1809         unsigned int hash = fuse_req_hash(unique);
1810         struct fuse_req *req;
1811
1812         list_for_each_entry(req, &fpq->processing[hash], list) {
1813                 if (req->in.h.unique == unique)
1814                         return req;
1815         }
1816         return NULL;
1817 }
1818
1819 static int copy_out_args(struct fuse_copy_state *cs, struct fuse_args *args,
1820                          unsigned nbytes)
1821 {
1822         unsigned reqsize = sizeof(struct fuse_out_header);
1823
1824         reqsize += fuse_len_args(args->out_numargs, args->out_args);
1825
1826         if (reqsize < nbytes || (reqsize > nbytes && !args->out_argvar))
1827                 return -EINVAL;
1828         else if (reqsize > nbytes) {
1829                 struct fuse_arg *lastarg = &args->out_args[args->out_numargs-1];
1830                 unsigned diffsize = reqsize - nbytes;
1831
1832                 if (diffsize > lastarg->size)
1833                         return -EINVAL;
1834                 lastarg->size -= diffsize;
1835         }
1836         return fuse_copy_args(cs, args->out_numargs, args->out_pages,
1837                               args->out_args, args->page_zeroing);
1838 }
1839
1840 /*
1841  * Write a single reply to a request.  First the header is copied from
1842  * the write buffer.  The request is then searched on the processing
1843  * list by the unique ID found in the header.  If found, then remove
1844  * it from the list and copy the rest of the buffer to the request.
1845  * The request is finished by calling fuse_request_end().
1846  */
1847 static ssize_t fuse_dev_do_write(struct fuse_dev *fud,
1848                                  struct fuse_copy_state *cs, size_t nbytes)
1849 {
1850         int err;
1851         struct fuse_conn *fc = fud->fc;
1852         struct fuse_pqueue *fpq = &fud->pq;
1853         struct fuse_req *req;
1854         struct fuse_out_header oh;
1855
1856         err = -EINVAL;
1857         if (nbytes < sizeof(struct fuse_out_header))
1858                 goto out;
1859
1860         err = fuse_copy_one(cs, &oh, sizeof(oh));
1861         if (err)
1862                 goto copy_finish;
1863
1864         err = -EINVAL;
1865         if (oh.len != nbytes)
1866                 goto copy_finish;
1867
1868         /*
1869          * Zero oh.unique indicates unsolicited notification message
1870          * and error contains notification code.
1871          */
1872         if (!oh.unique) {
1873                 err = fuse_notify(fc, oh.error, nbytes - sizeof(oh), cs);
1874                 goto out;
1875         }
1876
1877         err = -EINVAL;
1878         if (oh.error <= -512 || oh.error > 0)
1879                 goto copy_finish;
1880
1881         spin_lock(&fpq->lock);
1882         req = NULL;
1883         if (fpq->connected)
1884                 req = request_find(fpq, oh.unique & ~FUSE_INT_REQ_BIT);
1885
1886         err = -ENOENT;
1887         if (!req) {
1888                 spin_unlock(&fpq->lock);
1889                 goto copy_finish;
1890         }
1891
1892         /* Is it an interrupt reply ID? */
1893         if (oh.unique & FUSE_INT_REQ_BIT) {
1894                 __fuse_get_request(req);
1895                 spin_unlock(&fpq->lock);
1896
1897                 err = 0;
1898                 if (nbytes != sizeof(struct fuse_out_header))
1899                         err = -EINVAL;
1900                 else if (oh.error == -ENOSYS)
1901                         fc->no_interrupt = 1;
1902                 else if (oh.error == -EAGAIN)
1903                         err = queue_interrupt(req);
1904
1905                 fuse_put_request(req);
1906
1907                 goto copy_finish;
1908         }
1909
1910         clear_bit(FR_SENT, &req->flags);
1911         list_move(&req->list, &fpq->io);
1912         req->out.h = oh;
1913         set_bit(FR_LOCKED, &req->flags);
1914         spin_unlock(&fpq->lock);
1915         cs->req = req;
1916         if (!req->args->page_replace)
1917                 cs->move_pages = 0;
1918
1919         if (oh.error)
1920                 err = nbytes != sizeof(oh) ? -EINVAL : 0;
1921         else
1922                 err = copy_out_args(cs, req->args, nbytes);
1923         fuse_copy_finish(cs);
1924
1925         spin_lock(&fpq->lock);
1926         clear_bit(FR_LOCKED, &req->flags);
1927         if (!fpq->connected)
1928                 err = -ENOENT;
1929         else if (err)
1930                 req->out.h.error = -EIO;
1931         if (!test_bit(FR_PRIVATE, &req->flags))
1932                 list_del_init(&req->list);
1933         spin_unlock(&fpq->lock);
1934
1935         fuse_request_end(req);
1936 out:
1937         return err ? err : nbytes;
1938
1939 copy_finish:
1940         fuse_copy_finish(cs);
1941         goto out;
1942 }
1943
1944 static ssize_t fuse_dev_write(struct kiocb *iocb, struct iov_iter *from)
1945 {
1946         struct fuse_copy_state cs;
1947         struct fuse_dev *fud = fuse_get_dev(iocb->ki_filp);
1948
1949         if (!fud)
1950                 return -EPERM;
1951
1952         if (!user_backed_iter(from))
1953                 return -EINVAL;
1954
1955         fuse_copy_init(&cs, 0, from);
1956
1957         return fuse_dev_do_write(fud, &cs, iov_iter_count(from));
1958 }
1959
1960 static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
1961                                      struct file *out, loff_t *ppos,
1962                                      size_t len, unsigned int flags)
1963 {
1964         unsigned int head, tail, mask, count;
1965         unsigned nbuf;
1966         unsigned idx;
1967         struct pipe_buffer *bufs;
1968         struct fuse_copy_state cs;
1969         struct fuse_dev *fud;
1970         size_t rem;
1971         ssize_t ret;
1972
1973         fud = fuse_get_dev(out);
1974         if (!fud)
1975                 return -EPERM;
1976
1977         pipe_lock(pipe);
1978
1979         head = pipe->head;
1980         tail = pipe->tail;
1981         mask = pipe->ring_size - 1;
1982         count = head - tail;
1983
1984         bufs = kvmalloc_array(count, sizeof(struct pipe_buffer), GFP_KERNEL);
1985         if (!bufs) {
1986                 pipe_unlock(pipe);
1987                 return -ENOMEM;
1988         }
1989
1990         nbuf = 0;
1991         rem = 0;
1992         for (idx = tail; idx != head && rem < len; idx++)
1993                 rem += pipe->bufs[idx & mask].len;
1994
1995         ret = -EINVAL;
1996         if (rem < len)
1997                 goto out_free;
1998
1999         rem = len;
2000         while (rem) {
2001                 struct pipe_buffer *ibuf;
2002                 struct pipe_buffer *obuf;
2003
2004                 if (WARN_ON(nbuf >= count || tail == head))
2005                         goto out_free;
2006
2007                 ibuf = &pipe->bufs[tail & mask];
2008                 obuf = &bufs[nbuf];
2009
2010                 if (rem >= ibuf->len) {
2011                         *obuf = *ibuf;
2012                         ibuf->ops = NULL;
2013                         tail++;
2014                         pipe->tail = tail;
2015                 } else {
2016                         if (!pipe_buf_get(pipe, ibuf))
2017                                 goto out_free;
2018
2019                         *obuf = *ibuf;
2020                         obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
2021                         obuf->len = rem;
2022                         ibuf->offset += obuf->len;
2023                         ibuf->len -= obuf->len;
2024                 }
2025                 nbuf++;
2026                 rem -= obuf->len;
2027         }
2028         pipe_unlock(pipe);
2029
2030         fuse_copy_init(&cs, 0, NULL);
2031         cs.pipebufs = bufs;
2032         cs.nr_segs = nbuf;
2033         cs.pipe = pipe;
2034
2035         if (flags & SPLICE_F_MOVE)
2036                 cs.move_pages = 1;
2037
2038         ret = fuse_dev_do_write(fud, &cs, len);
2039
2040         pipe_lock(pipe);
2041 out_free:
2042         for (idx = 0; idx < nbuf; idx++) {
2043                 struct pipe_buffer *buf = &bufs[idx];
2044
2045                 if (buf->ops)
2046                         pipe_buf_release(pipe, buf);
2047         }
2048         pipe_unlock(pipe);
2049
2050         kvfree(bufs);
2051         return ret;
2052 }
2053
2054 static __poll_t fuse_dev_poll(struct file *file, poll_table *wait)
2055 {
2056         __poll_t mask = EPOLLOUT | EPOLLWRNORM;
2057         struct fuse_iqueue *fiq;
2058         struct fuse_dev *fud = fuse_get_dev(file);
2059
2060         if (!fud)
2061                 return EPOLLERR;
2062
2063         fiq = &fud->fc->iq;
2064         poll_wait(file, &fiq->waitq, wait);
2065
2066         spin_lock(&fiq->lock);
2067         if (!fiq->connected)
2068                 mask = EPOLLERR;
2069         else if (request_pending(fiq))
2070                 mask |= EPOLLIN | EPOLLRDNORM;
2071         spin_unlock(&fiq->lock);
2072
2073         return mask;
2074 }
2075
2076 /* Abort all requests on the given list (pending or processing) */
2077 static void end_requests(struct list_head *head)
2078 {
2079         while (!list_empty(head)) {
2080                 struct fuse_req *req;
2081                 req = list_entry(head->next, struct fuse_req, list);
2082                 req->out.h.error = -ECONNABORTED;
2083                 clear_bit(FR_SENT, &req->flags);
2084                 list_del_init(&req->list);
2085                 fuse_request_end(req);
2086         }
2087 }
2088
2089 static void end_polls(struct fuse_conn *fc)
2090 {
2091         struct rb_node *p;
2092
2093         p = rb_first(&fc->polled_files);
2094
2095         while (p) {
2096                 struct fuse_file *ff;
2097                 ff = rb_entry(p, struct fuse_file, polled_node);
2098                 wake_up_interruptible_all(&ff->poll_wait);
2099
2100                 p = rb_next(p);
2101         }
2102 }
2103
2104 /*
2105  * Abort all requests.
2106  *
2107  * Emergency exit in case of a malicious or accidental deadlock, or just a hung
2108  * filesystem.
2109  *
2110  * The same effect is usually achievable through killing the filesystem daemon
2111  * and all users of the filesystem.  The exception is the combination of an
2112  * asynchronous request and the tricky deadlock (see
2113  * Documentation/filesystems/fuse.rst).
2114  *
2115  * Aborting requests under I/O goes as follows: 1: Separate out unlocked
2116  * requests, they should be finished off immediately.  Locked requests will be
2117  * finished after unlock; see unlock_request(). 2: Finish off the unlocked
2118  * requests.  It is possible that some request will finish before we can.  This
2119  * is OK, the request will in that case be removed from the list before we touch
2120  * it.
2121  */
2122 void fuse_abort_conn(struct fuse_conn *fc)
2123 {
2124         struct fuse_iqueue *fiq = &fc->iq;
2125
2126         spin_lock(&fc->lock);
2127         if (fc->connected) {
2128                 struct fuse_dev *fud;
2129                 struct fuse_req *req, *next;
2130                 LIST_HEAD(to_end);
2131                 unsigned int i;
2132
2133                 /* Background queuing checks fc->connected under bg_lock */
2134                 spin_lock(&fc->bg_lock);
2135                 fc->connected = 0;
2136                 spin_unlock(&fc->bg_lock);
2137
2138                 fuse_set_initialized(fc);
2139                 list_for_each_entry(fud, &fc->devices, entry) {
2140                         struct fuse_pqueue *fpq = &fud->pq;
2141
2142                         spin_lock(&fpq->lock);
2143                         fpq->connected = 0;
2144                         list_for_each_entry_safe(req, next, &fpq->io, list) {
2145                                 req->out.h.error = -ECONNABORTED;
2146                                 spin_lock(&req->waitq.lock);
2147                                 set_bit(FR_ABORTED, &req->flags);
2148                                 if (!test_bit(FR_LOCKED, &req->flags)) {
2149                                         set_bit(FR_PRIVATE, &req->flags);
2150                                         __fuse_get_request(req);
2151                                         list_move(&req->list, &to_end);
2152                                 }
2153                                 spin_unlock(&req->waitq.lock);
2154                         }
2155                         for (i = 0; i < FUSE_PQ_HASH_SIZE; i++)
2156                                 list_splice_tail_init(&fpq->processing[i],
2157                                                       &to_end);
2158                         spin_unlock(&fpq->lock);
2159                 }
2160                 spin_lock(&fc->bg_lock);
2161                 fc->blocked = 0;
2162                 fc->max_background = UINT_MAX;
2163                 flush_bg_queue(fc);
2164                 spin_unlock(&fc->bg_lock);
2165
2166                 spin_lock(&fiq->lock);
2167                 fiq->connected = 0;
2168                 list_for_each_entry(req, &fiq->pending, list)
2169                         clear_bit(FR_PENDING, &req->flags);
2170                 list_splice_tail_init(&fiq->pending, &to_end);
2171                 while (forget_pending(fiq))
2172                         kfree(fuse_dequeue_forget(fiq, 1, NULL));
2173                 wake_up_all(&fiq->waitq);
2174                 spin_unlock(&fiq->lock);
2175                 kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
2176                 end_polls(fc);
2177                 wake_up_all(&fc->blocked_waitq);
2178                 spin_unlock(&fc->lock);
2179
2180                 end_requests(&to_end);
2181         } else {
2182                 spin_unlock(&fc->lock);
2183         }
2184 }
2185 EXPORT_SYMBOL_GPL(fuse_abort_conn);
2186
2187 void fuse_wait_aborted(struct fuse_conn *fc)
2188 {
2189         /* matches implicit memory barrier in fuse_drop_waiting() */
2190         smp_mb();
2191         wait_event(fc->blocked_waitq, atomic_read(&fc->num_waiting) == 0);
2192 }
2193
2194 int fuse_dev_release(struct inode *inode, struct file *file)
2195 {
2196         struct fuse_dev *fud = fuse_get_dev(file);
2197
2198         if (fud) {
2199                 struct fuse_conn *fc = fud->fc;
2200                 struct fuse_pqueue *fpq = &fud->pq;
2201                 LIST_HEAD(to_end);
2202                 unsigned int i;
2203
2204                 spin_lock(&fpq->lock);
2205                 WARN_ON(!list_empty(&fpq->io));
2206                 for (i = 0; i < FUSE_PQ_HASH_SIZE; i++)
2207                         list_splice_init(&fpq->processing[i], &to_end);
2208                 spin_unlock(&fpq->lock);
2209
2210                 end_requests(&to_end);
2211
2212                 /* Are we the last open device? */
2213                 if (atomic_dec_and_test(&fc->dev_count)) {
2214                         WARN_ON(fc->iq.fasync != NULL);
2215                         fuse_abort_conn(fc);
2216                 }
2217                 fuse_dev_free(fud);
2218         }
2219         return 0;
2220 }
2221 EXPORT_SYMBOL_GPL(fuse_dev_release);
2222
2223 static int fuse_dev_fasync(int fd, struct file *file, int on)
2224 {
2225         struct fuse_dev *fud = fuse_get_dev(file);
2226
2227         if (!fud)
2228                 return -EPERM;
2229
2230         /* No locking - fasync_helper does its own locking */
2231         return fasync_helper(fd, file, on, &fud->fc->iq.fasync);
2232 }
2233
2234 static int fuse_device_clone(struct fuse_conn *fc, struct file *new)
2235 {
2236         struct fuse_dev *fud;
2237
2238         if (new->private_data)
2239                 return -EINVAL;
2240
2241         fud = fuse_dev_alloc_install(fc);
2242         if (!fud)
2243                 return -ENOMEM;
2244
2245         new->private_data = fud;
2246         atomic_inc(&fc->dev_count);
2247
2248         return 0;
2249 }
2250
2251 static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
2252                            unsigned long arg)
2253 {
2254         int res;
2255         int oldfd;
2256         struct fuse_dev *fud = NULL;
2257
2258         switch (cmd) {
2259         case FUSE_DEV_IOC_CLONE:
2260                 res = -EFAULT;
2261                 if (!get_user(oldfd, (__u32 __user *)arg)) {
2262                         struct file *old = fget(oldfd);
2263
2264                         res = -EINVAL;
2265                         if (old) {
2266                                 /*
2267                                  * Check against file->f_op because CUSE
2268                                  * uses the same ioctl handler.
2269                                  */
2270                                 if (old->f_op == file->f_op &&
2271                                     old->f_cred->user_ns == file->f_cred->user_ns)
2272                                         fud = fuse_get_dev(old);
2273
2274                                 if (fud) {
2275                                         mutex_lock(&fuse_mutex);
2276                                         res = fuse_device_clone(fud->fc, file);
2277                                         mutex_unlock(&fuse_mutex);
2278                                 }
2279                                 fput(old);
2280                         }
2281                 }
2282                 break;
2283         default:
2284                 res = -ENOTTY;
2285                 break;
2286         }
2287         return res;
2288 }
2289
2290 const struct file_operations fuse_dev_operations = {
2291         .owner          = THIS_MODULE,
2292         .open           = fuse_dev_open,
2293         .llseek         = no_llseek,
2294         .read_iter      = fuse_dev_read,
2295         .splice_read    = fuse_dev_splice_read,
2296         .write_iter     = fuse_dev_write,
2297         .splice_write   = fuse_dev_splice_write,
2298         .poll           = fuse_dev_poll,
2299         .release        = fuse_dev_release,
2300         .fasync         = fuse_dev_fasync,
2301         .unlocked_ioctl = fuse_dev_ioctl,
2302         .compat_ioctl   = compat_ptr_ioctl,
2303 };
2304 EXPORT_SYMBOL_GPL(fuse_dev_operations);
2305
2306 static struct miscdevice fuse_miscdevice = {
2307         .minor = FUSE_MINOR,
2308         .name  = "fuse",
2309         .fops = &fuse_dev_operations,
2310 };
2311
2312 int __init fuse_dev_init(void)
2313 {
2314         int err = -ENOMEM;
2315         fuse_req_cachep = kmem_cache_create("fuse_request",
2316                                             sizeof(struct fuse_req),
2317                                             0, 0, NULL);
2318         if (!fuse_req_cachep)
2319                 goto out;
2320
2321         err = misc_register(&fuse_miscdevice);
2322         if (err)
2323                 goto out_cache_clean;
2324
2325         return 0;
2326
2327  out_cache_clean:
2328         kmem_cache_destroy(fuse_req_cachep);
2329  out:
2330         return err;
2331 }
2332
2333 void fuse_dev_cleanup(void)
2334 {
2335         misc_deregister(&fuse_miscdevice);
2336         kmem_cache_destroy(fuse_req_cachep);
2337 }