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   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/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 struct fuse_req *fuse_request_alloc_nofs(void)
  51 {
  52         struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, GFP_NOFS);
  53         if (req)
  54                 fuse_request_init(req);
  55         return req;
  56 }
  57
  58 void fuse_request_free(struct fuse_req *req)
  59 {
  60         kmem_cache_free(fuse_req_cachep, req);
  61 }
  62
  63 static void block_sigs(sigset_t *oldset)
  64 {
  65         sigset_t mask;
  66
  67         siginitsetinv(&mask, sigmask(SIGKILL));
  68         sigprocmask(SIG_BLOCK, &mask, oldset);
  69 }
  70
  71 static void restore_sigs(sigset_t *oldset)
  72 {
  73         sigprocmask(SIG_SETMASK, oldset, NULL);
  74 }
  75
  76 static void __fuse_get_request(struct fuse_req *req)
  77 {
  78         atomic_inc(&req->count);
  79 }
  80
  81 /* Must be called with > 1 refcount */
  82 static void __fuse_put_request(struct fuse_req *req)
  83 {
  84         BUG_ON(atomic_read(&req->count) < 2);
  85         atomic_dec(&req->count);
  86 }
  87
  88 static void fuse_req_init_context(struct fuse_req *req)
  89 {
  90         req->in.h.uid = current_fsuid();
  91         req->in.h.gid = current_fsgid();
  92         req->in.h.pid = current->pid;
  93 }
  94
  95 struct fuse_req *fuse_get_req(struct fuse_conn *fc)
  96 {
  97         struct fuse_req *req;
  98         sigset_t oldset;
  99         int intr;
 100         int err;
 101
 102         atomic_inc(&fc->num_waiting);
 103         block_sigs(&oldset);
 104         intr = wait_event_interruptible(fc->blocked_waitq, !fc->blocked);
 105         restore_sigs(&oldset);
 106         err = -EINTR;
 107         if (intr)
 108                 goto out;
 109
 110         err = -ENOTCONN;
 111         if (!fc->connected)
 112                 goto out;
 113
 114         req = fuse_request_alloc();
 115         err = -ENOMEM;
 116         if (!req)
 117                 goto out;
 118
 119         fuse_req_init_context(req);
 120         req->waiting = 1;
 121         return req;
 122
 123  out:
 124         atomic_dec(&fc->num_waiting);
 125         return ERR_PTR(err);
 126 }
 127
 128 /*
 129  * Return request in fuse_file->reserved_req.  However that may
 130  * currently be in use.  If that is the case, wait for it to become
 131  * available.
 132  */
 133 static struct fuse_req *get_reserved_req(struct fuse_conn *fc,
 134                                          struct file *file)
 135 {
 136         struct fuse_req *req = NULL;
 137         struct fuse_file *ff = file->private_data;
 138
 139         do {
 140                 wait_event(fc->reserved_req_waitq, ff->reserved_req);
 141                 spin_lock(&fc->lock);
 142                 if (ff->reserved_req) {
 143                         req = ff->reserved_req;
 144                         ff->reserved_req = NULL;
 145                         get_file(file);
 146                         req->stolen_file = file;
 147                 }
 148                 spin_unlock(&fc->lock);
 149         } while (!req);
 150
 151         return req;
 152 }
 153
 154 /*
 155  * Put stolen request back into fuse_file->reserved_req
 156  */
 157 static void put_reserved_req(struct fuse_conn *fc, struct fuse_req *req)
 158 {
 159         struct file *file = req->stolen_file;
 160         struct fuse_file *ff = file->private_data;
 161
 162         spin_lock(&fc->lock);
 163         fuse_request_init(req);
 164         BUG_ON(ff->reserved_req);
 165         ff->reserved_req = req;
 166         wake_up_all(&fc->reserved_req_waitq);
 167         spin_unlock(&fc->lock);
 168         fput(file);
 169 }
 170
 171 /*
 172  * Gets a requests for a file operation, always succeeds
 173  *
 174  * This is used for sending the FLUSH request, which must get to
 175  * userspace, due to POSIX locks which may need to be unlocked.
 176  *
 177  * If allocation fails due to OOM, use the reserved request in
 178  * fuse_file.
 179  *
 180  * This is very unlikely to deadlock accidentally, since the
 181  * filesystem should not have it's own file open.  If deadlock is
 182  * intentional, it can still be broken by "aborting" the filesystem.
 183  */
 184 struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file)
 185 {
 186         struct fuse_req *req;
 187
 188         atomic_inc(&fc->num_waiting);
 189         wait_event(fc->blocked_waitq, !fc->blocked);
 190         req = fuse_request_alloc();
 191         if (!req)
 192                 req = get_reserved_req(fc, file);
 193
 194         fuse_req_init_context(req);
 195         req->waiting = 1;
 196         return req;
 197 }
 198
 199 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
 200 {
 201         if (atomic_dec_and_test(&req->count)) {
 202                 if (req->waiting)
 203                         atomic_dec(&fc->num_waiting);
 204
 205                 if (req->stolen_file)
 206                         put_reserved_req(fc, req);
 207                 else
 208                         fuse_request_free(req);
 209         }
 210 }
 211
 212 static unsigned len_args(unsigned numargs, struct fuse_arg *args)
 213 {
 214         unsigned nbytes = 0;
 215         unsigned i;
 216
 217         for (i = 0; i < numargs; i++)
 218                 nbytes += args[i].size;
 219
 220         return nbytes;
 221 }
 222
 223 static u64 fuse_get_unique(struct fuse_conn *fc)
 224 {
 225         fc->reqctr++;
 226         /* zero is special */
 227         if (fc->reqctr == 0)
 228                 fc->reqctr = 1;
 229
 230         return fc->reqctr;
 231 }
 232
 233 static void queue_request(struct fuse_conn *fc, struct fuse_req *req)
 234 {
 235         req->in.h.unique = fuse_get_unique(fc);
 236         req->in.h.len = sizeof(struct fuse_in_header) +
 237                 len_args(req->in.numargs, (struct fuse_arg *) req->in.args);
 238         list_add_tail(&req->list, &fc->pending);
 239         req->state = FUSE_REQ_PENDING;
 240         if (!req->waiting) {
 241                 req->waiting = 1;
 242                 atomic_inc(&fc->num_waiting);
 243         }
 244         wake_up(&fc->waitq);
 245         kill_fasync(&fc->fasync, SIGIO, POLL_IN);
 246 }
 247
 248 static void flush_bg_queue(struct fuse_conn *fc)
 249 {
 250         while (fc->active_background < FUSE_MAX_BACKGROUND &&
 251                !list_empty(&fc->bg_queue)) {
 252                 struct fuse_req *req;
 253
 254                 req = list_entry(fc->bg_queue.next, struct fuse_req, list);
 255                 list_del(&req->list);
 256                 fc->active_background++;
 257                 queue_request(fc, req);
 258         }
 259 }
 260
 261 /*
 262  * This function is called when a request is finished.  Either a reply
 263  * has arrived or it was aborted (and not yet sent) or some error
 264  * occurred during communication with userspace, or the device file
 265  * was closed.  The requester thread is woken up (if still waiting),
 266  * the 'end' callback is called if given, else the reference to the
 267  * request is released
 268  *
 269  * Called with fc->lock, unlocks it
 270  */
 271 static void request_end(struct fuse_conn *fc, struct fuse_req *req)
 272 __releases(&fc->lock)
 273 {
 274         void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
 275         req->end = NULL;
 276         list_del(&req->list);
 277         list_del(&req->intr_entry);
 278         req->state = FUSE_REQ_FINISHED;
 279         if (req->background) {
 280                 if (fc->num_background == FUSE_MAX_BACKGROUND) {
 281                         fc->blocked = 0;
 282                         wake_up_all(&fc->blocked_waitq);
 283                 }
 284                 if (fc->num_background == FUSE_CONGESTION_THRESHOLD) {
 285                         clear_bdi_congested(&fc->bdi, READ);
 286                         clear_bdi_congested(&fc->bdi, WRITE);
 287                 }
 288                 fc->num_background--;
 289                 fc->active_background--;
 290                 flush_bg_queue(fc);
 291         }
 292         spin_unlock(&fc->lock);
 293         wake_up(&req->waitq);
 294         if (end)
 295                 end(fc, req);
 296         fuse_put_request(fc, req);
 297 }
 298
 299 static void wait_answer_interruptible(struct fuse_conn *fc,
 300                                       struct fuse_req *req)
 301 __releases(&fc->lock)
 302 __acquires(&fc->lock)
 303 {
 304         if (signal_pending(current))
 305                 return;
 306
 307         spin_unlock(&fc->lock);
 308         wait_event_interruptible(req->waitq, req->state == FUSE_REQ_FINISHED);
 309         spin_lock(&fc->lock);
 310 }
 311
 312 static void queue_interrupt(struct fuse_conn *fc, struct fuse_req *req)
 313 {
 314         list_add_tail(&req->intr_entry, &fc->interrupts);
 315         wake_up(&fc->waitq);
 316         kill_fasync(&fc->fasync, SIGIO, POLL_IN);
 317 }
 318
 319 static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
 320 __releases(&fc->lock)
 321 __acquires(&fc->lock)
 322 {
 323         if (!fc->no_interrupt) {
 324                 /* Any signal may interrupt this */
 325                 wait_answer_interruptible(fc, req);
 326
 327                 if (req->aborted)
 328                         goto aborted;
 329                 if (req->state == FUSE_REQ_FINISHED)
 330                         return;
 331
 332                 req->interrupted = 1;
 333                 if (req->state == FUSE_REQ_SENT)
 334                         queue_interrupt(fc, req);
 335         }
 336
 337         if (!req->force) {
 338                 sigset_t oldset;
 339
 340                 /* Only fatal signals may interrupt this */
 341                 block_sigs(&oldset);
 342                 wait_answer_interruptible(fc, req);
 343                 restore_sigs(&oldset);
 344
 345                 if (req->aborted)
 346                         goto aborted;
 347                 if (req->state == FUSE_REQ_FINISHED)
 348                         return;
 349
 350                 /* Request is not yet in userspace, bail out */
 351                 if (req->state == FUSE_REQ_PENDING) {
 352                         list_del(&req->list);
 353                         __fuse_put_request(req);
 354                         req->out.h.error = -EINTR;
 355                         return;
 356                 }
 357         }
 358
 359         /*
 360          * Either request is already in userspace, or it was forced.
 361          * Wait it out.
 362          */
 363         spin_unlock(&fc->lock);
 364         wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
 365         spin_lock(&fc->lock);
 366
 367         if (!req->aborted)
 368                 return;
 369
 370  aborted:
 371         BUG_ON(req->state != FUSE_REQ_FINISHED);
 372         if (req->locked) {
 373                 /* This is uninterruptible sleep, because data is
 374                    being copied to/from the buffers of req.  During
 375                    locked state, there mustn't be any filesystem
 376                    operation (e.g. page fault), since that could lead
 377                    to deadlock */
 378                 spin_unlock(&fc->lock);
 379                 wait_event(req->waitq, !req->locked);
 380                 spin_lock(&fc->lock);
 381         }
 382 }
 383
 384 void fuse_request_send(struct fuse_conn *fc, struct fuse_req *req)
 385 {
 386         req->isreply = 1;
 387         spin_lock(&fc->lock);
 388         if (!fc->connected)
 389                 req->out.h.error = -ENOTCONN;
 390         else if (fc->conn_error)
 391                 req->out.h.error = -ECONNREFUSED;
 392         else {
 393                 queue_request(fc, req);
 394                 /* acquire extra reference, since request is still needed
 395                    after request_end() */
 396                 __fuse_get_request(req);
 397
 398                 request_wait_answer(fc, req);
 399         }
 400         spin_unlock(&fc->lock);
 401 }
 402
 403 static void fuse_request_send_nowait_locked(struct fuse_conn *fc,
 404                                             struct fuse_req *req)
 405 {
 406         req->background = 1;
 407         fc->num_background++;
 408         if (fc->num_background == FUSE_MAX_BACKGROUND)
 409                 fc->blocked = 1;
 410         if (fc->num_background == FUSE_CONGESTION_THRESHOLD) {
 411                 set_bdi_congested(&fc->bdi, READ);
 412                 set_bdi_congested(&fc->bdi, WRITE);
 413         }
 414         list_add_tail(&req->list, &fc->bg_queue);
 415         flush_bg_queue(fc);
 416 }
 417
 418 static void fuse_request_send_nowait(struct fuse_conn *fc, struct fuse_req *req)
 419 {
 420         spin_lock(&fc->lock);
 421         if (fc->connected) {
 422                 fuse_request_send_nowait_locked(fc, req);
 423                 spin_unlock(&fc->lock);
 424         } else {
 425                 req->out.h.error = -ENOTCONN;
 426                 request_end(fc, req);
 427         }
 428 }
 429
 430 void fuse_request_send_noreply(struct fuse_conn *fc, struct fuse_req *req)
 431 {
 432         req->isreply = 0;
 433         fuse_request_send_nowait(fc, req);
 434 }
 435
 436 void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req)
 437 {
 438         req->isreply = 1;
 439         fuse_request_send_nowait(fc, req);
 440 }
 441
 442 /*
 443  * Called under fc->lock
 444  *
 445  * fc->connected must have been checked previously
 446  */
 447 void fuse_request_send_background_locked(struct fuse_conn *fc,
 448                                          struct fuse_req *req)
 449 {
 450         req->isreply = 1;
 451         fuse_request_send_nowait_locked(fc, req);
 452 }
 453
 454 /*
 455  * Lock the request.  Up to the next unlock_request() there mustn't be
 456  * anything that could cause a page-fault.  If the request was already
 457  * aborted bail out.
 458  */
 459 static int lock_request(struct fuse_conn *fc, struct fuse_req *req)
 460 {
 461         int err = 0;
 462         if (req) {
 463                 spin_lock(&fc->lock);
 464                 if (req->aborted)
 465                         err = -ENOENT;
 466                 else
 467                         req->locked = 1;
 468                 spin_unlock(&fc->lock);
 469         }
 470         return err;
 471 }
 472
 473 /*
 474  * Unlock request.  If it was aborted during being locked, the
 475  * requester thread is currently waiting for it to be unlocked, so
 476  * wake it up.
 477  */
 478 static void unlock_request(struct fuse_conn *fc, struct fuse_req *req)
 479 {
 480         if (req) {
 481                 spin_lock(&fc->lock);
 482                 req->locked = 0;
 483                 if (req->aborted)
 484                         wake_up(&req->waitq);
 485                 spin_unlock(&fc->lock);
 486         }
 487 }
 488
 489 struct fuse_copy_state {
 490         struct fuse_conn *fc;
 491         int write;
 492         struct fuse_req *req;
 493         const struct iovec *iov;
 494         unsigned long nr_segs;
 495         unsigned long seglen;
 496         unsigned long addr;
 497         struct page *pg;
 498         void *mapaddr;
 499         void *buf;
 500         unsigned len;
 501 };
 502
 503 static void fuse_copy_init(struct fuse_copy_state *cs, struct fuse_conn *fc,
 504                            int write, struct fuse_req *req,
 505                            const struct iovec *iov, unsigned long nr_segs)
 506 {
 507         memset(cs, 0, sizeof(*cs));
 508         cs->fc = fc;
 509         cs->write = write;
 510         cs->req = req;
 511         cs->iov = iov;
 512         cs->nr_segs = nr_segs;
 513 }
 514
 515 /* Unmap and put previous page of userspace buffer */
 516 static void fuse_copy_finish(struct fuse_copy_state *cs)
 517 {
 518         if (cs->mapaddr) {
 519                 kunmap_atomic(cs->mapaddr, KM_USER0);
 520                 if (cs->write) {
 521                         flush_dcache_page(cs->pg);
 522                         set_page_dirty_lock(cs->pg);
 523                 }
 524                 put_page(cs->pg);
 525                 cs->mapaddr = NULL;
 526         }
 527 }
 528
 529 /*
 530  * Get another pagefull of userspace buffer, and map it to kernel
 531  * address space, and lock request
 532  */
 533 static int fuse_copy_fill(struct fuse_copy_state *cs)
 534 {
 535         unsigned long offset;
 536         int err;
 537
 538         unlock_request(cs->fc, cs->req);
 539         fuse_copy_finish(cs);
 540         if (!cs->seglen) {
 541                 BUG_ON(!cs->nr_segs);
 542                 cs->seglen = cs->iov[0].iov_len;
 543                 cs->addr = (unsigned long) cs->iov[0].iov_base;
 544                 cs->iov++;
 545                 cs->nr_segs--;
 546         }
 547         down_read(&current->mm->mmap_sem);
 548         err = get_user_pages(current, current->mm, cs->addr, 1, cs->write, 0,
 549                              &cs->pg, NULL);
 550         up_read(&current->mm->mmap_sem);
 551         if (err < 0)
 552                 return err;
 553         BUG_ON(err != 1);
 554         offset = cs->addr % PAGE_SIZE;
 555         cs->mapaddr = kmap_atomic(cs->pg, KM_USER0);
 556         cs->buf = cs->mapaddr + offset;
 557         cs->len = min(PAGE_SIZE - offset, cs->seglen);
 558         cs->seglen -= cs->len;
 559         cs->addr += cs->len;
 560
 561         return lock_request(cs->fc, cs->req);
 562 }
 563
 564 /* Do as much copy to/from userspace buffer as we can */
 565 static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
 566 {
 567         unsigned ncpy = min(*size, cs->len);
 568         if (val) {
 569                 if (cs->write)
 570                         memcpy(cs->buf, *val, ncpy);
 571                 else
 572                         memcpy(*val, cs->buf, ncpy);
 573                 *val += ncpy;
 574         }
 575         *size -= ncpy;
 576         cs->len -= ncpy;
 577         cs->buf += ncpy;
 578         return ncpy;
 579 }
 580
 581 /*
 582  * Copy a page in the request to/from the userspace buffer.  Must be
 583  * done atomically
 584  */
 585 static int fuse_copy_page(struct fuse_copy_state *cs, struct page *page,
 586                           unsigned offset, unsigned count, int zeroing)
 587 {
 588         if (page && zeroing && count < PAGE_SIZE) {
 589                 void *mapaddr = kmap_atomic(page, KM_USER1);
 590                 memset(mapaddr, 0, PAGE_SIZE);
 591                 kunmap_atomic(mapaddr, KM_USER1);
 592         }
 593         while (count) {
 594                 if (!cs->len) {
 595                         int err = fuse_copy_fill(cs);
 596                         if (err)
 597                                 return err;
 598                 }
 599                 if (page) {
 600                         void *mapaddr = kmap_atomic(page, KM_USER1);
 601                         void *buf = mapaddr + offset;
 602                         offset += fuse_copy_do(cs, &buf, &count);
 603                         kunmap_atomic(mapaddr, KM_USER1);
 604                 } else
 605                         offset += fuse_copy_do(cs, NULL, &count);
 606         }
 607         if (page && !cs->write)
 608                 flush_dcache_page(page);
 609         return 0;
 610 }
 611
 612 /* Copy pages in the request to/from userspace buffer */
 613 static int fuse_copy_pages(struct fuse_copy_state *cs, unsigned nbytes,
 614                            int zeroing)
 615 {
 616         unsigned i;
 617         struct fuse_req *req = cs->req;
 618         unsigned offset = req->page_offset;
 619         unsigned count = min(nbytes, (unsigned) PAGE_SIZE - offset);
 620
 621         for (i = 0; i < req->num_pages && (nbytes || zeroing); i++) {
 622                 struct page *page = req->pages[i];
 623                 int err = fuse_copy_page(cs, page, offset, count, zeroing);
 624                 if (err)
 625                         return err;
 626
 627                 nbytes -= count;
 628                 count = min(nbytes, (unsigned) PAGE_SIZE);
 629                 offset = 0;
 630         }
 631         return 0;
 632 }
 633
 634 /* Copy a single argument in the request to/from userspace buffer */
 635 static int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned size)
 636 {
 637         while (size) {
 638                 if (!cs->len) {
 639                         int err = fuse_copy_fill(cs);
 640                         if (err)
 641                                 return err;
 642                 }
 643                 fuse_copy_do(cs, &val, &size);
 644         }
 645         return 0;
 646 }
 647
 648 /* Copy request arguments to/from userspace buffer */
 649 static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs,
 650                           unsigned argpages, struct fuse_arg *args,
 651                           int zeroing)
 652 {
 653         int err = 0;
 654         unsigned i;
 655
 656         for (i = 0; !err && i < numargs; i++)  {
 657                 struct fuse_arg *arg = &args[i];
 658                 if (i == numargs - 1 && argpages)
 659                         err = fuse_copy_pages(cs, arg->size, zeroing);
 660                 else
 661                         err = fuse_copy_one(cs, arg->value, arg->size);
 662         }
 663         return err;
 664 }
 665
 666 static int request_pending(struct fuse_conn *fc)
 667 {
 668         return !list_empty(&fc->pending) || !list_empty(&fc->interrupts);
 669 }
 670
 671 /* Wait until a request is available on the pending list */
 672 static void request_wait(struct fuse_conn *fc)
 673 __releases(&fc->lock)
 674 __acquires(&fc->lock)
 675 {
 676         DECLARE_WAITQUEUE(wait, current);
 677
 678         add_wait_queue_exclusive(&fc->waitq, &wait);
 679         while (fc->connected && !request_pending(fc)) {
 680                 set_current_state(TASK_INTERRUPTIBLE);
 681                 if (signal_pending(current))
 682                         break;
 683
 684                 spin_unlock(&fc->lock);
 685                 schedule();
 686                 spin_lock(&fc->lock);
 687         }
 688         set_current_state(TASK_RUNNING);
 689         remove_wait_queue(&fc->waitq, &wait);
 690 }
 691
 692 /*
 693  * Transfer an interrupt request to userspace
 694  *
 695  * Unlike other requests this is assembled on demand, without a need
 696  * to allocate a separate fuse_req structure.
 697  *
 698  * Called with fc->lock held, releases it
 699  */
 700 static int fuse_read_interrupt(struct fuse_conn *fc, struct fuse_req *req,
 701                                const struct iovec *iov, unsigned long nr_segs)
 702 __releases(&fc->lock)
 703 {
 704         struct fuse_copy_state cs;
 705         struct fuse_in_header ih;
 706         struct fuse_interrupt_in arg;
 707         unsigned reqsize = sizeof(ih) + sizeof(arg);
 708         int err;
 709
 710         list_del_init(&req->intr_entry);
 711         req->intr_unique = fuse_get_unique(fc);
 712         memset(&ih, 0, sizeof(ih));
 713         memset(&arg, 0, sizeof(arg));
 714         ih.len = reqsize;
 715         ih.opcode = FUSE_INTERRUPT;
 716         ih.unique = req->intr_unique;
 717         arg.unique = req->in.h.unique;
 718
 719         spin_unlock(&fc->lock);
 720         if (iov_length(iov, nr_segs) < reqsize)
 721                 return -EINVAL;
 722
 723         fuse_copy_init(&cs, fc, 1, NULL, iov, nr_segs);
 724         err = fuse_copy_one(&cs, &ih, sizeof(ih));
 725         if (!err)
 726                 err = fuse_copy_one(&cs, &arg, sizeof(arg));
 727         fuse_copy_finish(&cs);
 728
 729         return err ? err : reqsize;
 730 }
 731
 732 /*
 733  * Read a single request into the userspace filesystem's buffer.  This
 734  * function waits until a request is available, then removes it from
 735  * the pending list and copies request data to userspace buffer.  If
 736  * no reply is needed (FORGET) or request has been aborted or there
 737  * was an error during the copying then it's finished by calling
 738  * request_end().  Otherwise add it to the processing list, and set
 739  * the 'sent' flag.
 740  */
 741 static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
 742                               unsigned long nr_segs, loff_t pos)
 743 {
 744         int err;
 745         struct fuse_req *req;
 746         struct fuse_in *in;
 747         struct fuse_copy_state cs;
 748         unsigned reqsize;
 749         struct file *file = iocb->ki_filp;
 750         struct fuse_conn *fc = fuse_get_conn(file);
 751         if (!fc)
 752                 return -EPERM;
 753
 754  restart:
 755         spin_lock(&fc->lock);
 756         err = -EAGAIN;
 757         if ((file->f_flags & O_NONBLOCK) && fc->connected &&
 758             !request_pending(fc))
 759                 goto err_unlock;
 760
 761         request_wait(fc);
 762         err = -ENODEV;
 763         if (!fc->connected)
 764                 goto err_unlock;
 765         err = -ERESTARTSYS;
 766         if (!request_pending(fc))
 767                 goto err_unlock;
 768
 769         if (!list_empty(&fc->interrupts)) {
 770                 req = list_entry(fc->interrupts.next, struct fuse_req,
 771                                  intr_entry);
 772                 return fuse_read_interrupt(fc, req, iov, nr_segs);
 773         }
 774
 775         req = list_entry(fc->pending.next, struct fuse_req, list);
 776         req->state = FUSE_REQ_READING;
 777         list_move(&req->list, &fc->io);
 778
 779         in = &req->in;
 780         reqsize = in->h.len;
 781         /* If request is too large, reply with an error and restart the read */
 782         if (iov_length(iov, nr_segs) < reqsize) {
 783                 req->out.h.error = -EIO;
 784                 /* SETXATTR is special, since it may contain too large data */
 785                 if (in->h.opcode == FUSE_SETXATTR)
 786                         req->out.h.error = -E2BIG;
 787                 request_end(fc, req);
 788                 goto restart;
 789         }
 790         spin_unlock(&fc->lock);
 791         fuse_copy_init(&cs, fc, 1, req, iov, nr_segs);
 792         err = fuse_copy_one(&cs, &in->h, sizeof(in->h));
 793         if (!err)
 794                 err = fuse_copy_args(&cs, in->numargs, in->argpages,
 795                                      (struct fuse_arg *) in->args, 0);
 796         fuse_copy_finish(&cs);
 797         spin_lock(&fc->lock);
 798         req->locked = 0;
 799         if (req->aborted) {
 800                 request_end(fc, req);
 801                 return -ENODEV;
 802         }
 803         if (err) {
 804                 req->out.h.error = -EIO;
 805                 request_end(fc, req);
 806                 return err;
 807         }
 808         if (!req->isreply)
 809                 request_end(fc, req);
 810         else {
 811                 req->state = FUSE_REQ_SENT;
 812                 list_move_tail(&req->list, &fc->processing);
 813                 if (req->interrupted)
 814                         queue_interrupt(fc, req);
 815                 spin_unlock(&fc->lock);
 816         }
 817         return reqsize;
 818
 819  err_unlock:
 820         spin_unlock(&fc->lock);
 821         return err;
 822 }
 823
 824 static int fuse_notify_poll(struct fuse_conn *fc, unsigned int size,
 825                             struct fuse_copy_state *cs)
 826 {
 827         struct fuse_notify_poll_wakeup_out outarg;
 828         int err;
 829
 830         if (size != sizeof(outarg))
 831                 return -EINVAL;
 832
 833         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
 834         if (err)
 835                 return err;
 836
 837         return fuse_notify_poll_wakeup(fc, &outarg);
 838 }
 839
 840 static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
 841                        unsigned int size, struct fuse_copy_state *cs)
 842 {
 843         switch (code) {
 844         case FUSE_NOTIFY_POLL:
 845                 return fuse_notify_poll(fc, size, cs);
 846
 847         default:
 848                 return -EINVAL;
 849         }
 850 }
 851
 852 /* Look up request on processing list by unique ID */
 853 static struct fuse_req *request_find(struct fuse_conn *fc, u64 unique)
 854 {
 855         struct list_head *entry;
 856
 857         list_for_each(entry, &fc->processing) {
 858                 struct fuse_req *req;
 859                 req = list_entry(entry, struct fuse_req, list);
 860                 if (req->in.h.unique == unique || req->intr_unique == unique)
 861                         return req;
 862         }
 863         return NULL;
 864 }
 865
 866 static int copy_out_args(struct fuse_copy_state *cs, struct fuse_out *out,
 867                          unsigned nbytes)
 868 {
 869         unsigned reqsize = sizeof(struct fuse_out_header);
 870
 871         if (out->h.error)
 872                 return nbytes != reqsize ? -EINVAL : 0;
 873
 874         reqsize += len_args(out->numargs, out->args);
 875
 876         if (reqsize < nbytes || (reqsize > nbytes && !out->argvar))
 877                 return -EINVAL;
 878         else if (reqsize > nbytes) {
 879                 struct fuse_arg *lastarg = &out->args[out->numargs-1];
 880                 unsigned diffsize = reqsize - nbytes;
 881                 if (diffsize > lastarg->size)
 882                         return -EINVAL;
 883                 lastarg->size -= diffsize;
 884         }
 885         return fuse_copy_args(cs, out->numargs, out->argpages, out->args,
 886                               out->page_zeroing);
 887 }
 888
 889 /*
 890  * Write a single reply to a request.  First the header is copied from
 891  * the write buffer.  The request is then searched on the processing
 892  * list by the unique ID found in the header.  If found, then remove
 893  * it from the list and copy the rest of the buffer to the request.
 894  * The request is finished by calling request_end()
 895  */
 896 static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov,
 897                                unsigned long nr_segs, loff_t pos)
 898 {
 899         int err;
 900         unsigned nbytes = iov_length(iov, nr_segs);
 901         struct fuse_req *req;
 902         struct fuse_out_header oh;
 903         struct fuse_copy_state cs;
 904         struct fuse_conn *fc = fuse_get_conn(iocb->ki_filp);
 905         if (!fc)
 906                 return -EPERM;
 907
 908         fuse_copy_init(&cs, fc, 0, NULL, iov, nr_segs);
 909         if (nbytes < sizeof(struct fuse_out_header))
 910                 return -EINVAL;
 911
 912         err = fuse_copy_one(&cs, &oh, sizeof(oh));
 913         if (err)
 914                 goto err_finish;
 915
 916         err = -EINVAL;
 917         if (oh.len != nbytes)
 918                 goto err_finish;
 919
 920         /*
 921          * Zero oh.unique indicates unsolicited notification message
 922          * and error contains notification code.
 923          */
 924         if (!oh.unique) {
 925                 err = fuse_notify(fc, oh.error, nbytes - sizeof(oh), &cs);
 926                 fuse_copy_finish(&cs);
 927                 return err ? err : nbytes;
 928         }
 929
 930         err = -EINVAL;
 931         if (oh.error <= -1000 || oh.error > 0)
 932                 goto err_finish;
 933
 934         spin_lock(&fc->lock);
 935         err = -ENOENT;
 936         if (!fc->connected)
 937                 goto err_unlock;
 938
 939         req = request_find(fc, oh.unique);
 940         if (!req)
 941                 goto err_unlock;
 942
 943         if (req->aborted) {
 944                 spin_unlock(&fc->lock);
 945                 fuse_copy_finish(&cs);
 946                 spin_lock(&fc->lock);
 947                 request_end(fc, req);
 948                 return -ENOENT;
 949         }
 950         /* Is it an interrupt reply? */
 951         if (req->intr_unique == oh.unique) {
 952                 err = -EINVAL;
 953                 if (nbytes != sizeof(struct fuse_out_header))
 954                         goto err_unlock;
 955
 956                 if (oh.error == -ENOSYS)
 957                         fc->no_interrupt = 1;
 958                 else if (oh.error == -EAGAIN)
 959                         queue_interrupt(fc, req);
 960
 961                 spin_unlock(&fc->lock);
 962                 fuse_copy_finish(&cs);
 963                 return nbytes;
 964         }
 965
 966         req->state = FUSE_REQ_WRITING;
 967         list_move(&req->list, &fc->io);
 968         req->out.h = oh;
 969         req->locked = 1;
 970         cs.req = req;
 971         spin_unlock(&fc->lock);
 972
 973         err = copy_out_args(&cs, &req->out, nbytes);
 974         fuse_copy_finish(&cs);
 975
 976         spin_lock(&fc->lock);
 977         req->locked = 0;
 978         if (!err) {
 979                 if (req->aborted)
 980                         err = -ENOENT;
 981         } else if (!req->aborted)
 982                 req->out.h.error = -EIO;
 983         request_end(fc, req);
 984
 985         return err ? err : nbytes;
 986
 987  err_unlock:
 988         spin_unlock(&fc->lock);
 989  err_finish:
 990         fuse_copy_finish(&cs);
 991         return err;
 992 }
 993
 994 static unsigned fuse_dev_poll(struct file *file, poll_table *wait)
 995 {
 996         unsigned mask = POLLOUT | POLLWRNORM;
 997         struct fuse_conn *fc = fuse_get_conn(file);
 998         if (!fc)
 999                 return POLLERR;
1000
1001         poll_wait(file, &fc->waitq, wait);
1002
1003         spin_lock(&fc->lock);
1004         if (!fc->connected)
1005                 mask = POLLERR;
1006         else if (request_pending(fc))
1007                 mask |= POLLIN | POLLRDNORM;
1008         spin_unlock(&fc->lock);
1009
1010         return mask;
1011 }
1012
1013 /*
1014  * Abort all requests on the given list (pending or processing)
1015  *
1016  * This function releases and reacquires fc->lock
1017  */
1018 static void end_requests(struct fuse_conn *fc, struct list_head *head)
1019 __releases(&fc->lock)
1020 __acquires(&fc->lock)
1021 {
1022         while (!list_empty(head)) {
1023                 struct fuse_req *req;
1024                 req = list_entry(head->next, struct fuse_req, list);
1025                 req->out.h.error = -ECONNABORTED;
1026                 request_end(fc, req);
1027                 spin_lock(&fc->lock);
1028         }
1029 }
1030
1031 /*
1032  * Abort requests under I/O
1033  *
1034  * The requests are set to aborted and finished, and the request
1035  * waiter is woken up.  This will make request_wait_answer() wait
1036  * until the request is unlocked and then return.
1037  *
1038  * If the request is asynchronous, then the end function needs to be
1039  * called after waiting for the request to be unlocked (if it was
1040  * locked).
1041  */
1042 static void end_io_requests(struct fuse_conn *fc)
1043 __releases(&fc->lock)
1044 __acquires(&fc->lock)
1045 {
1046         while (!list_empty(&fc->io)) {
1047                 struct fuse_req *req =
1048                         list_entry(fc->io.next, struct fuse_req, list);
1049                 void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
1050
1051                 req->aborted = 1;
1052                 req->out.h.error = -ECONNABORTED;
1053                 req->state = FUSE_REQ_FINISHED;
1054                 list_del_init(&req->list);
1055                 wake_up(&req->waitq);
1056                 if (end) {
1057                         req->end = NULL;
1058                         __fuse_get_request(req);
1059                         spin_unlock(&fc->lock);
1060                         wait_event(req->waitq, !req->locked);
1061                         end(fc, req);
1062                         fuse_put_request(fc, req);
1063                         spin_lock(&fc->lock);
1064                 }
1065         }
1066 }
1067
1068 /*
1069  * Abort all requests.
1070  *
1071  * Emergency exit in case of a malicious or accidental deadlock, or
1072  * just a hung filesystem.
1073  *
1074  * The same effect is usually achievable through killing the
1075  * filesystem daemon and all users of the filesystem.  The exception
1076  * is the combination of an asynchronous request and the tricky
1077  * deadlock (see Documentation/filesystems/fuse.txt).
1078  *
1079  * During the aborting, progression of requests from the pending and
1080  * processing lists onto the io list, and progression of new requests
1081  * onto the pending list is prevented by req->connected being false.
1082  *
1083  * Progression of requests under I/O to the processing list is
1084  * prevented by the req->aborted flag being true for these requests.
1085  * For this reason requests on the io list must be aborted first.
1086  */
1087 void fuse_abort_conn(struct fuse_conn *fc)
1088 {
1089         spin_lock(&fc->lock);
1090         if (fc->connected) {
1091                 fc->connected = 0;
1092                 fc->blocked = 0;
1093                 end_io_requests(fc);
1094                 end_requests(fc, &fc->pending);
1095                 end_requests(fc, &fc->processing);
1096                 wake_up_all(&fc->waitq);
1097                 wake_up_all(&fc->blocked_waitq);
1098                 kill_fasync(&fc->fasync, SIGIO, POLL_IN);
1099         }
1100         spin_unlock(&fc->lock);
1101 }
1102
1103 static int fuse_dev_release(struct inode *inode, struct file *file)
1104 {
1105         struct fuse_conn *fc = fuse_get_conn(file);
1106         if (fc) {
1107                 spin_lock(&fc->lock);
1108                 fc->connected = 0;
1109                 end_requests(fc, &fc->pending);
1110                 end_requests(fc, &fc->processing);
1111                 spin_unlock(&fc->lock);
1112                 fuse_conn_put(fc);
1113         }
1114
1115         return 0;
1116 }
1117
1118 static int fuse_dev_fasync(int fd, struct file *file, int on)
1119 {
1120         struct fuse_conn *fc = fuse_get_conn(file);
1121         if (!fc)
1122                 return -EPERM;
1123
1124         /* No locking - fasync_helper does its own locking */
1125         return fasync_helper(fd, file, on, &fc->fasync);
1126 }
1127
1128 const struct file_operations fuse_dev_operations = {
1129         .owner          = THIS_MODULE,
1130         .llseek         = no_llseek,
1131         .read           = do_sync_read,
1132         .aio_read       = fuse_dev_read,
1133         .write          = do_sync_write,
1134         .aio_write      = fuse_dev_write,
1135         .poll           = fuse_dev_poll,
1136         .release        = fuse_dev_release,
1137         .fasync         = fuse_dev_fasync,
1138 };
1139
1140 static struct miscdevice fuse_miscdevice = {
1141         .minor = FUSE_MINOR,
1142         .name  = "fuse",
1143         .fops = &fuse_dev_operations,
1144 };
1145
1146 int __init fuse_dev_init(void)
1147 {
1148         int err = -ENOMEM;
1149         fuse_req_cachep = kmem_cache_create("fuse_request",
1150                                             sizeof(struct fuse_req),
1151                                             0, 0, NULL);
1152         if (!fuse_req_cachep)
1153                 goto out;
1154
1155         err = misc_register(&fuse_miscdevice);
1156         if (err)
1157                 goto out_cache_clean;
1158
1159         return 0;
1160
1161  out_cache_clean:
1162         kmem_cache_destroy(fuse_req_cachep);
1163  out:
1164         return err;
1165 }
1166
1167 void fuse_dev_cleanup(void)
1168 {
1169         misc_deregister(&fuse_miscdevice);
1170         kmem_cache_destroy(fuse_req_cachep);
1171 }