fs/fuse/dev.c

   1 /*
   2   FUSE: Filesystem in Userspace
   3   Copyright (C) 2001-2006  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/uio.h>
  15 #include <linux/miscdevice.h>
  16 #include <linux/pagemap.h>
  17 #include <linux/file.h>
  18 #include <linux/slab.h>
  19
  20 MODULE_ALIAS_MISCDEV(FUSE_MINOR);
  21
  22 static struct kmem_cache *fuse_req_cachep;
  23
  24 static struct fuse_conn *fuse_get_conn(struct file *file)
  25 {
  26         /*
  27          * Lockless access is OK, because file->private data is set
  28          * once during mount and is valid until the file is released.
  29          */
  30         return file->private_data;
  31 }
  32
  33 static void fuse_request_init(struct fuse_req *req)
  34 {
  35         memset(req, 0, sizeof(*req));
  36         INIT_LIST_HEAD(&req->list);
  37         INIT_LIST_HEAD(&req->intr_entry);
  38         init_waitqueue_head(&req->waitq);
  39         atomic_set(&req->count, 1);
  40 }
  41
  42 struct fuse_req *fuse_request_alloc(void)
  43 {
  44         struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, GFP_KERNEL);
  45         if (req)
  46                 fuse_request_init(req);
  47         return req;
  48 }
  49
  50 void fuse_request_free(struct fuse_req *req)
  51 {
  52         kmem_cache_free(fuse_req_cachep, req);
  53 }
  54
  55 static void block_sigs(sigset_t *oldset)
  56 {
  57         sigset_t mask;
  58
  59         siginitsetinv(&mask, sigmask(SIGKILL));
  60         sigprocmask(SIG_BLOCK, &mask, oldset);
  61 }
  62
  63 static void restore_sigs(sigset_t *oldset)
  64 {
  65         sigprocmask(SIG_SETMASK, oldset, NULL);
  66 }
  67
  68 static void __fuse_get_request(struct fuse_req *req)
  69 {
  70         atomic_inc(&req->count);
  71 }
  72
  73 /* Must be called with > 1 refcount */
  74 static void __fuse_put_request(struct fuse_req *req)
  75 {
  76         BUG_ON(atomic_read(&req->count) < 2);
  77         atomic_dec(&req->count);
  78 }
  79
  80 static void fuse_req_init_context(struct fuse_req *req)
  81 {
  82         req->in.h.uid = current->fsuid;
  83         req->in.h.gid = current->fsgid;
  84         req->in.h.pid = current->pid;
  85 }
  86
  87 struct fuse_req *fuse_get_req(struct fuse_conn *fc)
  88 {
  89         struct fuse_req *req;
  90         sigset_t oldset;
  91         int intr;
  92         int err;
  93
  94         atomic_inc(&fc->num_waiting);
  95         block_sigs(&oldset);
  96         intr = wait_event_interruptible(fc->blocked_waitq, !fc->blocked);
  97         restore_sigs(&oldset);
  98         err = -EINTR;
  99         if (intr)
 100                 goto out;
 101
 102         err = -ENOTCONN;
 103         if (!fc->connected)
 104                 goto out;
 105
 106         req = fuse_request_alloc();
 107         err = -ENOMEM;
 108         if (!req)
 109                 goto out;
 110
 111         fuse_req_init_context(req);
 112         req->waiting = 1;
 113         return req;
 114
 115  out:
 116         atomic_dec(&fc->num_waiting);
 117         return ERR_PTR(err);
 118 }
 119
 120 /*
 121  * Return request in fuse_file->reserved_req.  However that may
 122  * currently be in use.  If that is the case, wait for it to become
 123  * available.
 124  */
 125 static struct fuse_req *get_reserved_req(struct fuse_conn *fc,
 126                                          struct file *file)
 127 {
 128         struct fuse_req *req = NULL;
 129         struct fuse_file *ff = file->private_data;
 130
 131         do {
 132                 wait_event(fc->reserved_req_waitq, ff->reserved_req);
 133                 spin_lock(&fc->lock);
 134                 if (ff->reserved_req) {
 135                         req = ff->reserved_req;
 136                         ff->reserved_req = NULL;
 137                         get_file(file);
 138                         req->stolen_file = file;
 139                 }
 140                 spin_unlock(&fc->lock);
 141         } while (!req);
 142
 143         return req;
 144 }
 145
 146 /*
 147  * Put stolen request back into fuse_file->reserved_req
 148  */
 149 static void put_reserved_req(struct fuse_conn *fc, struct fuse_req *req)
 150 {
 151         struct file *file = req->stolen_file;
 152         struct fuse_file *ff = file->private_data;
 153
 154         spin_lock(&fc->lock);
 155         fuse_request_init(req);
 156         BUG_ON(ff->reserved_req);
 157         ff->reserved_req = req;
 158         wake_up_all(&fc->reserved_req_waitq);
 159         spin_unlock(&fc->lock);
 160         fput(file);
 161 }
 162
 163 /*
 164  * Gets a requests for a file operation, always succeeds
 165  *
 166  * This is used for sending the FLUSH request, which must get to
 167  * userspace, due to POSIX locks which may need to be unlocked.
 168  *
 169  * If allocation fails due to OOM, use the reserved request in
 170  * fuse_file.
 171  *
 172  * This is very unlikely to deadlock accidentally, since the
 173  * filesystem should not have it's own file open.  If deadlock is
 174  * intentional, it can still be broken by "aborting" the filesystem.
 175  */
 176 struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file)
 177 {
 178         struct fuse_req *req;
 179
 180         atomic_inc(&fc->num_waiting);
 181         wait_event(fc->blocked_waitq, !fc->blocked);
 182         req = fuse_request_alloc();
 183         if (!req)
 184                 req = get_reserved_req(fc, file);
 185
 186         fuse_req_init_context(req);
 187         req->waiting = 1;
 188         return req;
 189 }
 190
 191 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
 192 {
 193         if (atomic_dec_and_test(&req->count)) {
 194                 if (req->waiting)
 195                         atomic_dec(&fc->num_waiting);
 196
 197                 if (req->stolen_file)
 198                         put_reserved_req(fc, req);
 199                 else
 200                         fuse_request_free(req);
 201         }
 202 }
 203
 204 /*
 205  * This function is called when a request is finished.  Either a reply
 206  * has arrived or it was aborted (and not yet sent) or some error
 207  * occurred during communication with userspace, or the device file
 208  * was closed.  The requester thread is woken up (if still waiting),
 209  * the 'end' callback is called if given, else the reference to the
 210  * request is released
 211  *
 212  * Called with fc->lock, unlocks it
 213  */
 214 static void request_end(struct fuse_conn *fc, struct fuse_req *req)
 215         __releases(fc->lock)
 216 {
 217         void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
 218         req->end = NULL;
 219         list_del(&req->list);
 220         list_del(&req->intr_entry);
 221         req->state = FUSE_REQ_FINISHED;
 222         if (req->background) {
 223                 if (fc->num_background == FUSE_MAX_BACKGROUND) {
 224                         fc->blocked = 0;
 225                         wake_up_all(&fc->blocked_waitq);
 226                 }
 227                 if (fc->num_background == FUSE_CONGESTION_THRESHOLD) {
 228                         clear_bdi_congested(&fc->bdi, READ);
 229                         clear_bdi_congested(&fc->bdi, WRITE);
 230                 }
 231                 fc->num_background--;
 232         }
 233         spin_unlock(&fc->lock);
 234         wake_up(&req->waitq);
 235         if (end)
 236                 end(fc, req);
 237         else
 238                 fuse_put_request(fc, req);
 239 }
 240
 241 static void wait_answer_interruptible(struct fuse_conn *fc,
 242                                       struct fuse_req *req)
 243 {
 244         if (signal_pending(current))
 245                 return;
 246
 247         spin_unlock(&fc->lock);
 248         wait_event_interruptible(req->waitq, req->state == FUSE_REQ_FINISHED);
 249         spin_lock(&fc->lock);
 250 }
 251
 252 static void queue_interrupt(struct fuse_conn *fc, struct fuse_req *req)
 253 {
 254         list_add_tail(&req->intr_entry, &fc->interrupts);
 255         wake_up(&fc->waitq);
 256         kill_fasync(&fc->fasync, SIGIO, POLL_IN);
 257 }
 258
 259 /* Called with fc->lock held.  Releases, and then reacquires it. */
 260 static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
 261 {
 262         if (!fc->no_interrupt) {
 263                 /* Any signal may interrupt this */
 264                 wait_answer_interruptible(fc, req);
 265
 266                 if (req->aborted)
 267                         goto aborted;
 268                 if (req->state == FUSE_REQ_FINISHED)
 269                         return;
 270
 271                 req->interrupted = 1;
 272                 if (req->state == FUSE_REQ_SENT)
 273                         queue_interrupt(fc, req);
 274         }
 275
 276         if (!req->force) {
 277                 sigset_t oldset;
 278
 279                 /* Only fatal signals may interrupt this */
 280                 block_sigs(&oldset);
 281                 wait_answer_interruptible(fc, req);
 282                 restore_sigs(&oldset);
 283
 284                 if (req->aborted)
 285                         goto aborted;
 286                 if (req->state == FUSE_REQ_FINISHED)
 287                         return;
 288
 289                 /* Request is not yet in userspace, bail out */
 290                 if (req->state == FUSE_REQ_PENDING) {
 291                         list_del(&req->list);
 292                         __fuse_put_request(req);
 293                         req->out.h.error = -EINTR;
 294                         return;
 295                 }
 296         }
 297
 298         /*
 299          * Either request is already in userspace, or it was forced.
 300          * Wait it out.
 301          */
 302         spin_unlock(&fc->lock);
 303         wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
 304         spin_lock(&fc->lock);
 305
 306         if (!req->aborted)
 307                 return;
 308
 309  aborted:
 310         BUG_ON(req->state != FUSE_REQ_FINISHED);
 311         if (req->locked) {
 312                 /* This is uninterruptible sleep, because data is
 313                    being copied to/from the buffers of req.  During
 314                    locked state, there mustn't be any filesystem
 315                    operation (e.g. page fault), since that could lead
 316                    to deadlock */
 317                 spin_unlock(&fc->lock);
 318                 wait_event(req->waitq, !req->locked);
 319                 spin_lock(&fc->lock);
 320         }
 321 }
 322
 323 static unsigned len_args(unsigned numargs, struct fuse_arg *args)
 324 {
 325         unsigned nbytes = 0;
 326         unsigned i;
 327
 328         for (i = 0; i < numargs; i++)
 329                 nbytes += args[i].size;
 330
 331         return nbytes;
 332 }
 333
 334 static u64 fuse_get_unique(struct fuse_conn *fc)
 335  {
 336         fc->reqctr++;
 337         /* zero is special */
 338         if (fc->reqctr == 0)
 339                 fc->reqctr = 1;
 340
 341         return fc->reqctr;
 342 }
 343
 344 static void queue_request(struct fuse_conn *fc, struct fuse_req *req)
 345 {
 346         req->in.h.unique = fuse_get_unique(fc);
 347         req->in.h.len = sizeof(struct fuse_in_header) +
 348                 len_args(req->in.numargs, (struct fuse_arg *) req->in.args);
 349         list_add_tail(&req->list, &fc->pending);
 350         req->state = FUSE_REQ_PENDING;
 351         if (!req->waiting) {
 352                 req->waiting = 1;
 353                 atomic_inc(&fc->num_waiting);
 354         }
 355         wake_up(&fc->waitq);
 356         kill_fasync(&fc->fasync, SIGIO, POLL_IN);
 357 }
 358
 359 void request_send(struct fuse_conn *fc, struct fuse_req *req)
 360 {
 361         req->isreply = 1;
 362         spin_lock(&fc->lock);
 363         if (!fc->connected)
 364                 req->out.h.error = -ENOTCONN;
 365         else if (fc->conn_error)
 366                 req->out.h.error = -ECONNREFUSED;
 367         else {
 368                 queue_request(fc, req);
 369                 /* acquire extra reference, since request is still needed
 370                    after request_end() */
 371                 __fuse_get_request(req);
 372
 373                 request_wait_answer(fc, req);
 374         }
 375         spin_unlock(&fc->lock);
 376 }
 377
 378 static void request_send_nowait(struct fuse_conn *fc, struct fuse_req *req)
 379 {
 380         spin_lock(&fc->lock);
 381         if (fc->connected) {
 382                 req->background = 1;
 383                 fc->num_background++;
 384                 if (fc->num_background == FUSE_MAX_BACKGROUND)
 385                         fc->blocked = 1;
 386                 if (fc->num_background == FUSE_CONGESTION_THRESHOLD) {
 387                         set_bdi_congested(&fc->bdi, READ);
 388                         set_bdi_congested(&fc->bdi, WRITE);
 389                 }
 390
 391                 queue_request(fc, req);
 392                 spin_unlock(&fc->lock);
 393         } else {
 394                 req->out.h.error = -ENOTCONN;
 395                 request_end(fc, req);
 396         }
 397 }
 398
 399 void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req)
 400 {
 401         req->isreply = 0;
 402         request_send_nowait(fc, req);
 403 }
 404
 405 void request_send_background(struct fuse_conn *fc, struct fuse_req *req)
 406 {
 407         req->isreply = 1;
 408         request_send_nowait(fc, req);
 409 }
 410
 411 /*
 412  * Lock the request.  Up to the next unlock_request() there mustn't be
 413  * anything that could cause a page-fault.  If the request was already
 414  * aborted bail out.
 415  */
 416 static int lock_request(struct fuse_conn *fc, struct fuse_req *req)
 417 {
 418         int err = 0;
 419         if (req) {
 420                 spin_lock(&fc->lock);
 421                 if (req->aborted)
 422                         err = -ENOENT;
 423                 else
 424                         req->locked = 1;
 425                 spin_unlock(&fc->lock);
 426         }
 427         return err;
 428 }
 429
 430 /*
 431  * Unlock request.  If it was aborted during being locked, the
 432  * requester thread is currently waiting for it to be unlocked, so
 433  * wake it up.
 434  */
 435 static void unlock_request(struct fuse_conn *fc, struct fuse_req *req)
 436 {
 437         if (req) {
 438                 spin_lock(&fc->lock);
 439                 req->locked = 0;
 440                 if (req->aborted)
 441                         wake_up(&req->waitq);
 442                 spin_unlock(&fc->lock);
 443         }
 444 }
 445
 446 struct fuse_copy_state {
 447         struct fuse_conn *fc;
 448         int write;
 449         struct fuse_req *req;
 450         const struct iovec *iov;
 451         unsigned long nr_segs;
 452         unsigned long seglen;
 453         unsigned long addr;
 454         struct page *pg;
 455         void *mapaddr;
 456         void *buf;
 457         unsigned len;
 458 };
 459
 460 static void fuse_copy_init(struct fuse_copy_state *cs, struct fuse_conn *fc,
 461                            int write, struct fuse_req *req,
 462                            const struct iovec *iov, unsigned long nr_segs)
 463 {
 464         memset(cs, 0, sizeof(*cs));
 465         cs->fc = fc;
 466         cs->write = write;
 467         cs->req = req;
 468         cs->iov = iov;
 469         cs->nr_segs = nr_segs;
 470 }
 471
 472 /* Unmap and put previous page of userspace buffer */
 473 static void fuse_copy_finish(struct fuse_copy_state *cs)
 474 {
 475         if (cs->mapaddr) {
 476                 kunmap_atomic(cs->mapaddr, KM_USER0);
 477                 if (cs->write) {
 478                         flush_dcache_page(cs->pg);
 479                         set_page_dirty_lock(cs->pg);
 480                 }
 481                 put_page(cs->pg);
 482                 cs->mapaddr = NULL;
 483         }
 484 }
 485
 486 /*
 487  * Get another pagefull of userspace buffer, and map it to kernel
 488  * address space, and lock request
 489  */
 490 static int fuse_copy_fill(struct fuse_copy_state *cs)
 491 {
 492         unsigned long offset;
 493         int err;
 494
 495         unlock_request(cs->fc, cs->req);
 496         fuse_copy_finish(cs);
 497         if (!cs->seglen) {
 498                 BUG_ON(!cs->nr_segs);
 499                 cs->seglen = cs->iov[0].iov_len;
 500                 cs->addr = (unsigned long) cs->iov[0].iov_base;
 501                 cs->iov ++;
 502                 cs->nr_segs --;
 503         }
 504         down_read(&current->mm->mmap_sem);
 505         err = get_user_pages(current, current->mm, cs->addr, 1, cs->write, 0,
 506                              &cs->pg, NULL);
 507         up_read(&current->mm->mmap_sem);
 508         if (err < 0)
 509                 return err;
 510         BUG_ON(err != 1);
 511         offset = cs->addr % PAGE_SIZE;
 512         cs->mapaddr = kmap_atomic(cs->pg, KM_USER0);
 513         cs->buf = cs->mapaddr + offset;
 514         cs->len = min(PAGE_SIZE - offset, cs->seglen);
 515         cs->seglen -= cs->len;
 516         cs->addr += cs->len;
 517
 518         return lock_request(cs->fc, cs->req);
 519 }
 520
 521 /* Do as much copy to/from userspace buffer as we can */
 522 static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
 523 {
 524         unsigned ncpy = min(*size, cs->len);
 525         if (val) {
 526                 if (cs->write)
 527                         memcpy(cs->buf, *val, ncpy);
 528                 else
 529                         memcpy(*val, cs->buf, ncpy);
 530                 *val += ncpy;
 531         }
 532         *size -= ncpy;
 533         cs->len -= ncpy;
 534         cs->buf += ncpy;
 535         return ncpy;
 536 }
 537
 538 /*
 539  * Copy a page in the request to/from the userspace buffer.  Must be
 540  * done atomically
 541  */
 542 static int fuse_copy_page(struct fuse_copy_state *cs, struct page *page,
 543                           unsigned offset, unsigned count, int zeroing)
 544 {
 545         if (page && zeroing && count < PAGE_SIZE) {
 546                 void *mapaddr = kmap_atomic(page, KM_USER1);
 547                 memset(mapaddr, 0, PAGE_SIZE);
 548                 kunmap_atomic(mapaddr, KM_USER1);
 549         }
 550         while (count) {
 551                 int err;
 552                 if (!cs->len && (err = fuse_copy_fill(cs)))
 553                         return err;
 554                 if (page) {
 555                         void *mapaddr = kmap_atomic(page, KM_USER1);
 556                         void *buf = mapaddr + offset;
 557                         offset += fuse_copy_do(cs, &buf, &count);
 558                         kunmap_atomic(mapaddr, KM_USER1);
 559                 } else
 560                         offset += fuse_copy_do(cs, NULL, &count);
 561         }
 562         if (page && !cs->write)
 563                 flush_dcache_page(page);
 564         return 0;
 565 }
 566
 567 /* Copy pages in the request to/from userspace buffer */
 568 static int fuse_copy_pages(struct fuse_copy_state *cs, unsigned nbytes,
 569                            int zeroing)
 570 {
 571         unsigned i;
 572         struct fuse_req *req = cs->req;
 573         unsigned offset = req->page_offset;
 574         unsigned count = min(nbytes, (unsigned) PAGE_SIZE - offset);
 575
 576         for (i = 0; i < req->num_pages && (nbytes || zeroing); i++) {
 577                 struct page *page = req->pages[i];
 578                 int err = fuse_copy_page(cs, page, offset, count, zeroing);
 579                 if (err)
 580                         return err;
 581
 582                 nbytes -= count;
 583                 count = min(nbytes, (unsigned) PAGE_SIZE);
 584                 offset = 0;
 585         }
 586         return 0;
 587 }
 588
 589 /* Copy a single argument in the request to/from userspace buffer */
 590 static int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned size)
 591 {
 592         while (size) {
 593                 int err;
 594                 if (!cs->len && (err = fuse_copy_fill(cs)))
 595                         return err;
 596                 fuse_copy_do(cs, &val, &size);
 597         }
 598         return 0;
 599 }
 600
 601 /* Copy request arguments to/from userspace buffer */
 602 static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs,
 603                           unsigned argpages, struct fuse_arg *args,
 604                           int zeroing)
 605 {
 606         int err = 0;
 607         unsigned i;
 608
 609         for (i = 0; !err && i < numargs; i++)  {
 610                 struct fuse_arg *arg = &args[i];
 611                 if (i == numargs - 1 && argpages)
 612                         err = fuse_copy_pages(cs, arg->size, zeroing);
 613                 else
 614                         err = fuse_copy_one(cs, arg->value, arg->size);
 615         }
 616         return err;
 617 }
 618
 619 static int request_pending(struct fuse_conn *fc)
 620 {
 621         return !list_empty(&fc->pending) || !list_empty(&fc->interrupts);
 622 }
 623
 624 /* Wait until a request is available on the pending list */
 625 static void request_wait(struct fuse_conn *fc)
 626 {
 627         DECLARE_WAITQUEUE(wait, current);
 628
 629         add_wait_queue_exclusive(&fc->waitq, &wait);
 630         while (fc->connected && !request_pending(fc)) {
 631                 set_current_state(TASK_INTERRUPTIBLE);
 632                 if (signal_pending(current))
 633                         break;
 634
 635                 spin_unlock(&fc->lock);
 636                 schedule();
 637                 spin_lock(&fc->lock);
 638         }
 639         set_current_state(TASK_RUNNING);
 640         remove_wait_queue(&fc->waitq, &wait);
 641 }
 642
 643 /*
 644  * Transfer an interrupt request to userspace
 645  *
 646  * Unlike other requests this is assembled on demand, without a need
 647  * to allocate a separate fuse_req structure.
 648  *
 649  * Called with fc->lock held, releases it
 650  */
 651 static int fuse_read_interrupt(struct fuse_conn *fc, struct fuse_req *req,
 652                                const struct iovec *iov, unsigned long nr_segs)
 653         __releases(fc->lock)
 654 {
 655         struct fuse_copy_state cs;
 656         struct fuse_in_header ih;
 657         struct fuse_interrupt_in arg;
 658         unsigned reqsize = sizeof(ih) + sizeof(arg);
 659         int err;
 660
 661         list_del_init(&req->intr_entry);
 662         req->intr_unique = fuse_get_unique(fc);
 663         memset(&ih, 0, sizeof(ih));
 664         memset(&arg, 0, sizeof(arg));
 665         ih.len = reqsize;
 666         ih.opcode = FUSE_INTERRUPT;
 667         ih.unique = req->intr_unique;
 668         arg.unique = req->in.h.unique;
 669
 670         spin_unlock(&fc->lock);
 671         if (iov_length(iov, nr_segs) < reqsize)
 672                 return -EINVAL;
 673
 674         fuse_copy_init(&cs, fc, 1, NULL, iov, nr_segs);
 675         err = fuse_copy_one(&cs, &ih, sizeof(ih));
 676         if (!err)
 677                 err = fuse_copy_one(&cs, &arg, sizeof(arg));
 678         fuse_copy_finish(&cs);
 679
 680         return err ? err : reqsize;
 681 }
 682
 683 /*
 684  * Read a single request into the userspace filesystem's buffer.  This
 685  * function waits until a request is available, then removes it from
 686  * the pending list and copies request data to userspace buffer.  If
 687  * no reply is needed (FORGET) or request has been aborted or there
 688  * was an error during the copying then it's finished by calling
 689  * request_end().  Otherwise add it to the processing list, and set
 690  * the 'sent' flag.
 691  */
 692 static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
 693                               unsigned long nr_segs, loff_t pos)
 694 {
 695         int err;
 696         struct fuse_req *req;
 697         struct fuse_in *in;
 698         struct fuse_copy_state cs;
 699         unsigned reqsize;
 700         struct file *file = iocb->ki_filp;
 701         struct fuse_conn *fc = fuse_get_conn(file);
 702         if (!fc)
 703                 return -EPERM;
 704
 705  restart:
 706         spin_lock(&fc->lock);
 707         err = -EAGAIN;
 708         if ((file->f_flags & O_NONBLOCK) && fc->connected &&
 709             !request_pending(fc))
 710                 goto err_unlock;
 711
 712         request_wait(fc);
 713         err = -ENODEV;
 714         if (!fc->connected)
 715                 goto err_unlock;
 716         err = -ERESTARTSYS;
 717         if (!request_pending(fc))
 718                 goto err_unlock;
 719
 720         if (!list_empty(&fc->interrupts)) {
 721                 req = list_entry(fc->interrupts.next, struct fuse_req,
 722                                  intr_entry);
 723                 return fuse_read_interrupt(fc, req, iov, nr_segs);
 724         }
 725
 726         req = list_entry(fc->pending.next, struct fuse_req, list);
 727         req->state = FUSE_REQ_READING;
 728         list_move(&req->list, &fc->io);
 729
 730         in = &req->in;
 731         reqsize = in->h.len;
 732         /* If request is too large, reply with an error and restart the read */
 733         if (iov_length(iov, nr_segs) < reqsize) {
 734                 req->out.h.error = -EIO;
 735                 /* SETXATTR is special, since it may contain too large data */
 736                 if (in->h.opcode == FUSE_SETXATTR)
 737                         req->out.h.error = -E2BIG;
 738                 request_end(fc, req);
 739                 goto restart;
 740         }
 741         spin_unlock(&fc->lock);
 742         fuse_copy_init(&cs, fc, 1, req, iov, nr_segs);
 743         err = fuse_copy_one(&cs, &in->h, sizeof(in->h));
 744         if (!err)
 745                 err = fuse_copy_args(&cs, in->numargs, in->argpages,
 746                                      (struct fuse_arg *) in->args, 0);
 747         fuse_copy_finish(&cs);
 748         spin_lock(&fc->lock);
 749         req->locked = 0;
 750         if (req->aborted) {
 751                 request_end(fc, req);
 752                 return -ENODEV;
 753         }
 754         if (err) {
 755                 req->out.h.error = -EIO;
 756                 request_end(fc, req);
 757                 return err;
 758         }
 759         if (!req->isreply)
 760                 request_end(fc, req);
 761         else {
 762                 req->state = FUSE_REQ_SENT;
 763                 list_move_tail(&req->list, &fc->processing);
 764                 if (req->interrupted)
 765                         queue_interrupt(fc, req);
 766                 spin_unlock(&fc->lock);
 767         }
 768         return reqsize;
 769
 770  err_unlock:
 771         spin_unlock(&fc->lock);
 772         return err;
 773 }
 774
 775 /* Look up request on processing list by unique ID */
 776 static struct fuse_req *request_find(struct fuse_conn *fc, u64 unique)
 777 {
 778         struct list_head *entry;
 779
 780         list_for_each(entry, &fc->processing) {
 781                 struct fuse_req *req;
 782                 req = list_entry(entry, struct fuse_req, list);
 783                 if (req->in.h.unique == unique || req->intr_unique == unique)
 784                         return req;
 785         }
 786         return NULL;
 787 }
 788
 789 static int copy_out_args(struct fuse_copy_state *cs, struct fuse_out *out,
 790                          unsigned nbytes)
 791 {
 792         unsigned reqsize = sizeof(struct fuse_out_header);
 793
 794         if (out->h.error)
 795                 return nbytes != reqsize ? -EINVAL : 0;
 796
 797         reqsize += len_args(out->numargs, out->args);
 798
 799         if (reqsize < nbytes || (reqsize > nbytes && !out->argvar))
 800                 return -EINVAL;
 801         else if (reqsize > nbytes) {
 802                 struct fuse_arg *lastarg = &out->args[out->numargs-1];
 803                 unsigned diffsize = reqsize - nbytes;
 804                 if (diffsize > lastarg->size)
 805                         return -EINVAL;
 806                 lastarg->size -= diffsize;
 807         }
 808         return fuse_copy_args(cs, out->numargs, out->argpages, out->args,
 809                               out->page_zeroing);
 810 }
 811
 812 /*
 813  * Write a single reply to a request.  First the header is copied from
 814  * the write buffer.  The request is then searched on the processing
 815  * list by the unique ID found in the header.  If found, then remove
 816  * it from the list and copy the rest of the buffer to the request.
 817  * The request is finished by calling request_end()
 818  */
 819 static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov,
 820                                unsigned long nr_segs, loff_t pos)
 821 {
 822         int err;
 823         unsigned nbytes = iov_length(iov, nr_segs);
 824         struct fuse_req *req;
 825         struct fuse_out_header oh;
 826         struct fuse_copy_state cs;
 827         struct fuse_conn *fc = fuse_get_conn(iocb->ki_filp);
 828         if (!fc)
 829                 return -EPERM;
 830
 831         fuse_copy_init(&cs, fc, 0, NULL, iov, nr_segs);
 832         if (nbytes < sizeof(struct fuse_out_header))
 833                 return -EINVAL;
 834
 835         err = fuse_copy_one(&cs, &oh, sizeof(oh));
 836         if (err)
 837                 goto err_finish;
 838         err = -EINVAL;
 839         if (!oh.unique || oh.error <= -1000 || oh.error > 0 ||
 840             oh.len != nbytes)
 841                 goto err_finish;
 842
 843         spin_lock(&fc->lock);
 844         err = -ENOENT;
 845         if (!fc->connected)
 846                 goto err_unlock;
 847
 848         req = request_find(fc, oh.unique);
 849         if (!req)
 850                 goto err_unlock;
 851
 852         if (req->aborted) {
 853                 spin_unlock(&fc->lock);
 854                 fuse_copy_finish(&cs);
 855                 spin_lock(&fc->lock);
 856                 request_end(fc, req);
 857                 return -ENOENT;
 858         }
 859         /* Is it an interrupt reply? */
 860         if (req->intr_unique == oh.unique) {
 861                 err = -EINVAL;
 862                 if (nbytes != sizeof(struct fuse_out_header))
 863                         goto err_unlock;
 864
 865                 if (oh.error == -ENOSYS)
 866                         fc->no_interrupt = 1;
 867                 else if (oh.error == -EAGAIN)
 868                         queue_interrupt(fc, req);
 869
 870                 spin_unlock(&fc->lock);
 871                 fuse_copy_finish(&cs);
 872                 return nbytes;
 873         }
 874
 875         req->state = FUSE_REQ_WRITING;
 876         list_move(&req->list, &fc->io);
 877         req->out.h = oh;
 878         req->locked = 1;
 879         cs.req = req;
 880         spin_unlock(&fc->lock);
 881
 882         err = copy_out_args(&cs, &req->out, nbytes);
 883         fuse_copy_finish(&cs);
 884
 885         spin_lock(&fc->lock);
 886         req->locked = 0;
 887         if (!err) {
 888                 if (req->aborted)
 889                         err = -ENOENT;
 890         } else if (!req->aborted)
 891                 req->out.h.error = -EIO;
 892         request_end(fc, req);
 893
 894         return err ? err : nbytes;
 895
 896  err_unlock:
 897         spin_unlock(&fc->lock);
 898  err_finish:
 899         fuse_copy_finish(&cs);
 900         return err;
 901 }
 902
 903 static unsigned fuse_dev_poll(struct file *file, poll_table *wait)
 904 {
 905         unsigned mask = POLLOUT | POLLWRNORM;
 906         struct fuse_conn *fc = fuse_get_conn(file);
 907         if (!fc)
 908                 return POLLERR;
 909
 910         poll_wait(file, &fc->waitq, wait);
 911
 912         spin_lock(&fc->lock);
 913         if (!fc->connected)
 914                 mask = POLLERR;
 915         else if (request_pending(fc))
 916                 mask |= POLLIN | POLLRDNORM;
 917         spin_unlock(&fc->lock);
 918
 919         return mask;
 920 }
 921
 922 /*
 923  * Abort all requests on the given list (pending or processing)
 924  *
 925  * This function releases and reacquires fc->lock
 926  */
 927 static void end_requests(struct fuse_conn *fc, struct list_head *head)
 928 {
 929         while (!list_empty(head)) {
 930                 struct fuse_req *req;
 931                 req = list_entry(head->next, struct fuse_req, list);
 932                 req->out.h.error = -ECONNABORTED;
 933                 request_end(fc, req);
 934                 spin_lock(&fc->lock);
 935         }
 936 }
 937
 938 /*
 939  * Abort requests under I/O
 940  *
 941  * The requests are set to aborted and finished, and the request
 942  * waiter is woken up.  This will make request_wait_answer() wait
 943  * until the request is unlocked and then return.
 944  *
 945  * If the request is asynchronous, then the end function needs to be
 946  * called after waiting for the request to be unlocked (if it was
 947  * locked).
 948  */
 949 static void end_io_requests(struct fuse_conn *fc)
 950 {
 951         while (!list_empty(&fc->io)) {
 952                 struct fuse_req *req =
 953                         list_entry(fc->io.next, struct fuse_req, list);
 954                 void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
 955
 956                 req->aborted = 1;
 957                 req->out.h.error = -ECONNABORTED;
 958                 req->state = FUSE_REQ_FINISHED;
 959                 list_del_init(&req->list);
 960                 wake_up(&req->waitq);
 961                 if (end) {
 962                         req->end = NULL;
 963                         /* The end function will consume this reference */
 964                         __fuse_get_request(req);
 965                         spin_unlock(&fc->lock);
 966                         wait_event(req->waitq, !req->locked);
 967                         end(fc, req);
 968                         spin_lock(&fc->lock);
 969                 }
 970         }
 971 }
 972
 973 /*
 974  * Abort all requests.
 975  *
 976  * Emergency exit in case of a malicious or accidental deadlock, or
 977  * just a hung filesystem.
 978  *
 979  * The same effect is usually achievable through killing the
 980  * filesystem daemon and all users of the filesystem.  The exception
 981  * is the combination of an asynchronous request and the tricky
 982  * deadlock (see Documentation/filesystems/fuse.txt).
 983  *
 984  * During the aborting, progression of requests from the pending and
 985  * processing lists onto the io list, and progression of new requests
 986  * onto the pending list is prevented by req->connected being false.
 987  *
 988  * Progression of requests under I/O to the processing list is
 989  * prevented by the req->aborted flag being true for these requests.
 990  * For this reason requests on the io list must be aborted first.
 991  */
 992 void fuse_abort_conn(struct fuse_conn *fc)
 993 {
 994         spin_lock(&fc->lock);
 995         if (fc->connected) {
 996                 fc->connected = 0;
 997                 fc->blocked = 0;
 998                 end_io_requests(fc);
 999                 end_requests(fc, &fc->pending);
1000                 end_requests(fc, &fc->processing);
1001                 wake_up_all(&fc->waitq);
1002                 wake_up_all(&fc->blocked_waitq);
1003                 kill_fasync(&fc->fasync, SIGIO, POLL_IN);
1004         }
1005         spin_unlock(&fc->lock);
1006 }
1007
1008 static int fuse_dev_release(struct inode *inode, struct file *file)
1009 {
1010         struct fuse_conn *fc = fuse_get_conn(file);
1011         if (fc) {
1012                 spin_lock(&fc->lock);
1013                 fc->connected = 0;
1014                 end_requests(fc, &fc->pending);
1015                 end_requests(fc, &fc->processing);
1016                 spin_unlock(&fc->lock);
1017                 fasync_helper(-1, file, 0, &fc->fasync);
1018                 fuse_conn_put(fc);
1019         }
1020
1021         return 0;
1022 }
1023
1024 static int fuse_dev_fasync(int fd, struct file *file, int on)
1025 {
1026         struct fuse_conn *fc = fuse_get_conn(file);
1027         if (!fc)
1028                 return -EPERM;
1029
1030         /* No locking - fasync_helper does its own locking */
1031         return fasync_helper(fd, file, on, &fc->fasync);
1032 }
1033
1034 const struct file_operations fuse_dev_operations = {
1035         .owner          = THIS_MODULE,
1036         .llseek         = no_llseek,
1037         .read           = do_sync_read,
1038         .aio_read       = fuse_dev_read,
1039         .write          = do_sync_write,
1040         .aio_write      = fuse_dev_write,
1041         .poll           = fuse_dev_poll,
1042         .release        = fuse_dev_release,
1043         .fasync         = fuse_dev_fasync,
1044 };
1045
1046 static struct miscdevice fuse_miscdevice = {
1047         .minor = FUSE_MINOR,
1048         .name  = "fuse",
1049         .fops = &fuse_dev_operations,
1050 };
1051
1052 int __init fuse_dev_init(void)
1053 {
1054         int err = -ENOMEM;
1055         fuse_req_cachep = kmem_cache_create("fuse_request",
1056                                             sizeof(struct fuse_req),
1057                                             0, 0, NULL);
1058         if (!fuse_req_cachep)
1059                 goto out;
1060
1061         err = misc_register(&fuse_miscdevice);
1062         if (err)
1063                 goto out_cache_clean;
1064
1065         return 0;
1066
1067  out_cache_clean:
1068         kmem_cache_destroy(fuse_req_cachep);
1069  out:
1070         return err;
1071 }
1072
1073 void fuse_dev_cleanup(void)
1074 {
1075         misc_deregister(&fuse_miscdevice);
1076         kmem_cache_destroy(fuse_req_cachep);
1077 }