fs/fuse/dev.c

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This source file includes following definitions.
fuse_get_dev
fuse_request_init
fuse_request_alloc
fuse_request_free
__fuse_get_request
__fuse_put_request
fuse_set_initialized
fuse_block_alloc
fuse_drop_waiting
fuse_get_req
fuse_put_request
fuse_len_args
fuse_get_unique
fuse_req_hash
fuse_dev_wake_and_unlock
queue_request_and_unlock
fuse_queue_forget
flush_bg_queue
fuse_request_end
queue_interrupt
request_wait_answer
__fuse_request_send
fuse_adjust_compat
fuse_force_creds
fuse_args_to_req
fuse_simple_request
fuse_request_queue_background
fuse_simple_background
fuse_simple_notify_reply
lock_request
unlock_request
fuse_copy_init
fuse_copy_finish
fuse_copy_fill
fuse_copy_do
fuse_check_page
fuse_try_move_page
fuse_ref_page
fuse_copy_page
fuse_copy_pages
fuse_copy_one
fuse_copy_args
forget_pending
request_pending
fuse_read_interrupt
fuse_dequeue_forget
fuse_read_single_forget
fuse_read_batch_forget
fuse_read_forget
fuse_dev_do_read
fuse_dev_open
fuse_dev_read
fuse_dev_splice_read
fuse_notify_poll
fuse_notify_inval_inode
fuse_notify_inval_entry
fuse_notify_delete
fuse_notify_store
fuse_retrieve_end
fuse_retrieve
fuse_notify_retrieve
fuse_notify
request_find
copy_out_args
fuse_dev_do_write
fuse_dev_write
fuse_dev_splice_write
fuse_dev_poll
end_requests
end_polls
fuse_abort_conn
fuse_wait_aborted
fuse_dev_release
fuse_dev_fasync
fuse_device_clone
fuse_dev_ioctl
fuse_dev_init
fuse_dev_cleanup
   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_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 }
  51 
  52 static struct fuse_req *fuse_request_alloc(gfp_t flags)
  53 {
  54         struct fuse_req *req = kmem_cache_zalloc(fuse_req_cachep, flags);
  55         if (req)
  56                 fuse_request_init(req);
  57 
  58         return req;
  59 }
  60 
  61 static void fuse_request_free(struct fuse_req *req)
  62 {
  63         kmem_cache_free(fuse_req_cachep, req);
  64 }
  65 
  66 static void __fuse_get_request(struct fuse_req *req)
  67 {
  68         refcount_inc(&req->count);
  69 }
  70 
  71 /* Must be called with > 1 refcount */
  72 static void __fuse_put_request(struct fuse_req *req)
  73 {
  74         refcount_dec(&req->count);
  75 }
  76 
  77 void fuse_set_initialized(struct fuse_conn *fc)
  78 {
  79         /* Make sure stores before this are seen on another CPU */
  80         smp_wmb();
  81         fc->initialized = 1;
  82 }
  83 
  84 static bool fuse_block_alloc(struct fuse_conn *fc, bool for_background)
  85 {
  86         return !fc->initialized || (for_background && fc->blocked);
  87 }
  88 
  89 static void fuse_drop_waiting(struct fuse_conn *fc)
  90 {
  91         /*
  92          * lockess check of fc->connected is okay, because atomic_dec_and_test()
  93          * provides a memory barrier mached with the one in fuse_wait_aborted()
  94          * to ensure no wake-up is missed.
  95          */
  96         if (atomic_dec_and_test(&fc->num_waiting) &&
  97             !READ_ONCE(fc->connected)) {
  98                 /* wake up aborters */
  99                 wake_up_all(&fc->blocked_waitq);
 100         }
 101 }
 102 
 103 static void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
 104 
 105 static struct fuse_req *fuse_get_req(struct fuse_conn *fc, bool for_background)
 106 {
 107         struct fuse_req *req;
 108         int err;
 109         atomic_inc(&fc->num_waiting);
 110 
 111         if (fuse_block_alloc(fc, for_background)) {
 112                 err = -EINTR;
 113                 if (wait_event_killable_exclusive(fc->blocked_waitq,
 114                                 !fuse_block_alloc(fc, for_background)))
 115                         goto out;
 116         }
 117         /* Matches smp_wmb() in fuse_set_initialized() */
 118         smp_rmb();
 119 
 120         err = -ENOTCONN;
 121         if (!fc->connected)
 122                 goto out;
 123 
 124         err = -ECONNREFUSED;
 125         if (fc->conn_error)
 126                 goto out;
 127 
 128         req = fuse_request_alloc(GFP_KERNEL);
 129         err = -ENOMEM;
 130         if (!req) {
 131                 if (for_background)
 132                         wake_up(&fc->blocked_waitq);
 133                 goto out;
 134         }
 135 
 136         req->in.h.uid = from_kuid(fc->user_ns, current_fsuid());
 137         req->in.h.gid = from_kgid(fc->user_ns, current_fsgid());
 138         req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns);
 139 
 140         __set_bit(FR_WAITING, &req->flags);
 141         if (for_background)
 142                 __set_bit(FR_BACKGROUND, &req->flags);
 143 
 144         if (unlikely(req->in.h.uid == ((uid_t)-1) ||
 145                      req->in.h.gid == ((gid_t)-1))) {
 146                 fuse_put_request(fc, req);
 147                 return ERR_PTR(-EOVERFLOW);
 148         }
 149         return req;
 150 
 151  out:
 152         fuse_drop_waiting(fc);
 153         return ERR_PTR(err);
 154 }
 155 
 156 static void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
 157 {
 158         if (refcount_dec_and_test(&req->count)) {
 159                 if (test_bit(FR_BACKGROUND, &req->flags)) {
 160                         /*
 161                          * We get here in the unlikely case that a background
 162                          * request was allocated but not sent
 163                          */
 164                         spin_lock(&fc->bg_lock);
 165                         if (!fc->blocked)
 166                                 wake_up(&fc->blocked_waitq);
 167                         spin_unlock(&fc->bg_lock);
 168                 }
 169 
 170                 if (test_bit(FR_WAITING, &req->flags)) {
 171                         __clear_bit(FR_WAITING, &req->flags);
 172                         fuse_drop_waiting(fc);
 173                 }
 174 
 175                 fuse_request_free(req);
 176         }
 177 }
 178 
 179 unsigned int fuse_len_args(unsigned int numargs, struct fuse_arg *args)
 180 {
 181         unsigned nbytes = 0;
 182         unsigned i;
 183 
 184         for (i = 0; i < numargs; i++)
 185                 nbytes += args[i].size;
 186 
 187         return nbytes;
 188 }
 189 EXPORT_SYMBOL_GPL(fuse_len_args);
 190 
 191 u64 fuse_get_unique(struct fuse_iqueue *fiq)
 192 {
 193         fiq->reqctr += FUSE_REQ_ID_STEP;
 194         return fiq->reqctr;
 195 }
 196 EXPORT_SYMBOL_GPL(fuse_get_unique);
 197 
 198 static unsigned int fuse_req_hash(u64 unique)
 199 {
 200         return hash_long(unique & ~FUSE_INT_REQ_BIT, FUSE_PQ_HASH_BITS);
 201 }
 202 
 203 /**
 204  * A new request is available, wake fiq->waitq
 205  */
 206 static void fuse_dev_wake_and_unlock(struct fuse_iqueue *fiq)
 207 __releases(fiq->lock)
 208 {
 209         wake_up(&fiq->waitq);
 210         kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
 211         spin_unlock(&fiq->lock);
 212 }
 213 
 214 const struct fuse_iqueue_ops fuse_dev_fiq_ops = {
 215         .wake_forget_and_unlock         = fuse_dev_wake_and_unlock,
 216         .wake_interrupt_and_unlock      = fuse_dev_wake_and_unlock,
 217         .wake_pending_and_unlock        = fuse_dev_wake_and_unlock,
 218 };
 219 EXPORT_SYMBOL_GPL(fuse_dev_fiq_ops);
 220 
 221 static void queue_request_and_unlock(struct fuse_iqueue *fiq,
 222                                      struct fuse_req *req)
 223 __releases(fiq->lock)
 224 {
 225         req->in.h.len = sizeof(struct fuse_in_header) +
 226                 fuse_len_args(req->args->in_numargs,
 227                               (struct fuse_arg *) req->args->in_args);
 228         list_add_tail(&req->list, &fiq->pending);
 229         fiq->ops->wake_pending_and_unlock(fiq);
 230 }
 231 
 232 void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
 233                        u64 nodeid, u64 nlookup)
 234 {
 235         struct fuse_iqueue *fiq = &fc->iq;
 236 
 237         forget->forget_one.nodeid = nodeid;
 238         forget->forget_one.nlookup = nlookup;
 239 
 240         spin_lock(&fiq->lock);
 241         if (fiq->connected) {
 242                 fiq->forget_list_tail->next = forget;
 243                 fiq->forget_list_tail = forget;
 244                 fiq->ops->wake_forget_and_unlock(fiq);
 245         } else {
 246                 kfree(forget);
 247                 spin_unlock(&fiq->lock);
 248         }
 249 }
 250 
 251 static void flush_bg_queue(struct fuse_conn *fc)
 252 {
 253         struct fuse_iqueue *fiq = &fc->iq;
 254 
 255         while (fc->active_background < fc->max_background &&
 256                !list_empty(&fc->bg_queue)) {
 257                 struct fuse_req *req;
 258 
 259                 req = list_first_entry(&fc->bg_queue, struct fuse_req, list);
 260                 list_del(&req->list);
 261                 fc->active_background++;
 262                 spin_lock(&fiq->lock);
 263                 req->in.h.unique = fuse_get_unique(fiq);
 264                 queue_request_and_unlock(fiq, req);
 265         }
 266 }
 267 
 268 /*
 269  * This function is called when a request is finished.  Either a reply
 270  * has arrived or it was aborted (and not yet sent) or some error
 271  * occurred during communication with userspace, or the device file
 272  * was closed.  The requester thread is woken up (if still waiting),
 273  * the 'end' callback is called if given, else the reference to the
 274  * request is released
 275  */
 276 void fuse_request_end(struct fuse_conn *fc, struct fuse_req *req)
 277 {
 278         struct fuse_iqueue *fiq = &fc->iq;
 279 
 280         if (test_and_set_bit(FR_FINISHED, &req->flags))
 281                 goto put_request;
 282 
 283         /*
 284          * test_and_set_bit() implies smp_mb() between bit
 285          * changing and below intr_entry check. Pairs with
 286          * smp_mb() from queue_interrupt().
 287          */
 288         if (!list_empty(&req->intr_entry)) {
 289                 spin_lock(&fiq->lock);
 290                 list_del_init(&req->intr_entry);
 291                 spin_unlock(&fiq->lock);
 292         }
 293         WARN_ON(test_bit(FR_PENDING, &req->flags));
 294         WARN_ON(test_bit(FR_SENT, &req->flags));
 295         if (test_bit(FR_BACKGROUND, &req->flags)) {
 296                 spin_lock(&fc->bg_lock);
 297                 clear_bit(FR_BACKGROUND, &req->flags);
 298                 if (fc->num_background == fc->max_background) {
 299                         fc->blocked = 0;
 300                         wake_up(&fc->blocked_waitq);
 301                 } else if (!fc->blocked) {
 302                         /*
 303                          * Wake up next waiter, if any.  It's okay to use
 304                          * waitqueue_active(), as we've already synced up
 305                          * fc->blocked with waiters with the wake_up() call
 306                          * above.
 307                          */
 308                         if (waitqueue_active(&fc->blocked_waitq))
 309                                 wake_up(&fc->blocked_waitq);
 310                 }
 311 
 312                 if (fc->num_background == fc->congestion_threshold && fc->sb) {
 313                         clear_bdi_congested(fc->sb->s_bdi, BLK_RW_SYNC);
 314                         clear_bdi_congested(fc->sb->s_bdi, BLK_RW_ASYNC);
 315                 }
 316                 fc->num_background--;
 317                 fc->active_background--;
 318                 flush_bg_queue(fc);
 319                 spin_unlock(&fc->bg_lock);
 320         } else {
 321                 /* Wake up waiter sleeping in request_wait_answer() */
 322                 wake_up(&req->waitq);
 323         }
 324 
 325         if (test_bit(FR_ASYNC, &req->flags))
 326                 req->args->end(fc, req->args, req->out.h.error);
 327 put_request:
 328         fuse_put_request(fc, req);
 329 }
 330 EXPORT_SYMBOL_GPL(fuse_request_end);
 331 
 332 static int queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req)
 333 {
 334         spin_lock(&fiq->lock);
 335         /* Check for we've sent request to interrupt this req */
 336         if (unlikely(!test_bit(FR_INTERRUPTED, &req->flags))) {
 337                 spin_unlock(&fiq->lock);
 338                 return -EINVAL;
 339         }
 340 
 341         if (list_empty(&req->intr_entry)) {
 342                 list_add_tail(&req->intr_entry, &fiq->interrupts);
 343                 /*
 344                  * Pairs with smp_mb() implied by test_and_set_bit()
 345                  * from request_end().
 346                  */
 347                 smp_mb();
 348                 if (test_bit(FR_FINISHED, &req->flags)) {
 349                         list_del_init(&req->intr_entry);
 350                         spin_unlock(&fiq->lock);
 351                         return 0;
 352                 }
 353                 fiq->ops->wake_interrupt_and_unlock(fiq);
 354         } else {
 355                 spin_unlock(&fiq->lock);
 356         }
 357         return 0;
 358 }
 359 
 360 static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
 361 {
 362         struct fuse_iqueue *fiq = &fc->iq;
 363         int err;
 364 
 365         if (!fc->no_interrupt) {
 366                 /* Any signal may interrupt this */
 367                 err = wait_event_interruptible(req->waitq,
 368                                         test_bit(FR_FINISHED, &req->flags));
 369                 if (!err)
 370                         return;
 371 
 372                 set_bit(FR_INTERRUPTED, &req->flags);
 373                 /* matches barrier in fuse_dev_do_read() */
 374                 smp_mb__after_atomic();
 375                 if (test_bit(FR_SENT, &req->flags))
 376                         queue_interrupt(fiq, req);
 377         }
 378 
 379         if (!test_bit(FR_FORCE, &req->flags)) {
 380                 /* Only fatal signals may interrupt this */
 381                 err = wait_event_killable(req->waitq,
 382                                         test_bit(FR_FINISHED, &req->flags));
 383                 if (!err)
 384                         return;
 385 
 386                 spin_lock(&fiq->lock);
 387                 /* Request is not yet in userspace, bail out */
 388                 if (test_bit(FR_PENDING, &req->flags)) {
 389                         list_del(&req->list);
 390                         spin_unlock(&fiq->lock);
 391                         __fuse_put_request(req);
 392                         req->out.h.error = -EINTR;
 393                         return;
 394                 }
 395                 spin_unlock(&fiq->lock);
 396         }
 397 
 398         /*
 399          * Either request is already in userspace, or it was forced.
 400          * Wait it out.
 401          */
 402         wait_event(req->waitq, test_bit(FR_FINISHED, &req->flags));
 403 }
 404 
 405 static void __fuse_request_send(struct fuse_conn *fc, struct fuse_req *req)
 406 {
 407         struct fuse_iqueue *fiq = &fc->iq;
 408 
 409         BUG_ON(test_bit(FR_BACKGROUND, &req->flags));
 410         spin_lock(&fiq->lock);
 411         if (!fiq->connected) {
 412                 spin_unlock(&fiq->lock);
 413                 req->out.h.error = -ENOTCONN;
 414         } else {
 415                 req->in.h.unique = fuse_get_unique(fiq);
 416                 /* acquire extra reference, since request is still needed
 417                    after fuse_request_end() */
 418                 __fuse_get_request(req);
 419                 queue_request_and_unlock(fiq, req);
 420 
 421                 request_wait_answer(fc, req);
 422                 /* Pairs with smp_wmb() in fuse_request_end() */
 423                 smp_rmb();
 424         }
 425 }
 426 
 427 static void fuse_adjust_compat(struct fuse_conn *fc, struct fuse_args *args)
 428 {
 429         if (fc->minor < 4 && args->opcode == FUSE_STATFS)
 430                 args->out_args[0].size = FUSE_COMPAT_STATFS_SIZE;
 431 
 432         if (fc->minor < 9) {
 433                 switch (args->opcode) {
 434                 case FUSE_LOOKUP:
 435                 case FUSE_CREATE:
 436                 case FUSE_MKNOD:
 437                 case FUSE_MKDIR:
 438                 case FUSE_SYMLINK:
 439                 case FUSE_LINK:
 440                         args->out_args[0].size = FUSE_COMPAT_ENTRY_OUT_SIZE;
 441                         break;
 442                 case FUSE_GETATTR:
 443                 case FUSE_SETATTR:
 444                         args->out_args[0].size = FUSE_COMPAT_ATTR_OUT_SIZE;
 445                         break;
 446                 }
 447         }
 448         if (fc->minor < 12) {
 449                 switch (args->opcode) {
 450                 case FUSE_CREATE:
 451                         args->in_args[0].size = sizeof(struct fuse_open_in);
 452                         break;
 453                 case FUSE_MKNOD:
 454                         args->in_args[0].size = FUSE_COMPAT_MKNOD_IN_SIZE;
 455                         break;
 456                 }
 457         }
 458 }
 459 
 460 static void fuse_force_creds(struct fuse_conn *fc, struct fuse_req *req)
 461 {
 462         req->in.h.uid = from_kuid_munged(fc->user_ns, current_fsuid());
 463         req->in.h.gid = from_kgid_munged(fc->user_ns, current_fsgid());
 464         req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns);
 465 }
 466 
 467 static void fuse_args_to_req(struct fuse_req *req, struct fuse_args *args)
 468 {
 469         req->in.h.opcode = args->opcode;
 470         req->in.h.nodeid = args->nodeid;
 471         req->args = args;
 472         if (args->end)
 473                 __set_bit(FR_ASYNC, &req->flags);
 474 }
 475 
 476 ssize_t fuse_simple_request(struct fuse_conn *fc, struct fuse_args *args)
 477 {
 478         struct fuse_req *req;
 479         ssize_t ret;
 480 
 481         if (args->force) {
 482                 atomic_inc(&fc->num_waiting);
 483                 req = fuse_request_alloc(GFP_KERNEL | __GFP_NOFAIL);
 484 
 485                 if (!args->nocreds)
 486                         fuse_force_creds(fc, req);
 487 
 488                 __set_bit(FR_WAITING, &req->flags);
 489                 __set_bit(FR_FORCE, &req->flags);
 490         } else {
 491                 WARN_ON(args->nocreds);
 492                 req = fuse_get_req(fc, false);
 493                 if (IS_ERR(req))
 494                         return PTR_ERR(req);
 495         }
 496 
 497         /* Needs to be done after fuse_get_req() so that fc->minor is valid */
 498         fuse_adjust_compat(fc, args);
 499         fuse_args_to_req(req, args);
 500 
 501         if (!args->noreply)
 502                 __set_bit(FR_ISREPLY, &req->flags);
 503         __fuse_request_send(fc, req);
 504         ret = req->out.h.error;
 505         if (!ret && args->out_argvar) {
 506                 BUG_ON(args->out_numargs == 0);
 507                 ret = args->out_args[args->out_numargs - 1].size;
 508         }
 509         fuse_put_request(fc, req);
 510 
 511         return ret;
 512 }
 513 
 514 static bool fuse_request_queue_background(struct fuse_conn *fc,
 515                                           struct fuse_req *req)
 516 {
 517         bool queued = false;
 518 
 519         WARN_ON(!test_bit(FR_BACKGROUND, &req->flags));
 520         if (!test_bit(FR_WAITING, &req->flags)) {
 521                 __set_bit(FR_WAITING, &req->flags);
 522                 atomic_inc(&fc->num_waiting);
 523         }
 524         __set_bit(FR_ISREPLY, &req->flags);
 525         spin_lock(&fc->bg_lock);
 526         if (likely(fc->connected)) {
 527                 fc->num_background++;
 528                 if (fc->num_background == fc->max_background)
 529                         fc->blocked = 1;
 530                 if (fc->num_background == fc->congestion_threshold && fc->sb) {
 531                         set_bdi_congested(fc->sb->s_bdi, BLK_RW_SYNC);
 532                         set_bdi_congested(fc->sb->s_bdi, BLK_RW_ASYNC);
 533                 }
 534                 list_add_tail(&req->list, &fc->bg_queue);
 535                 flush_bg_queue(fc);
 536                 queued = true;
 537         }
 538         spin_unlock(&fc->bg_lock);
 539 
 540         return queued;
 541 }
 542 
 543 int fuse_simple_background(struct fuse_conn *fc, struct fuse_args *args,
 544                             gfp_t gfp_flags)
 545 {
 546         struct fuse_req *req;
 547 
 548         if (args->force) {
 549                 WARN_ON(!args->nocreds);
 550                 req = fuse_request_alloc(gfp_flags);
 551                 if (!req)
 552                         return -ENOMEM;
 553                 __set_bit(FR_BACKGROUND, &req->flags);
 554         } else {
 555                 WARN_ON(args->nocreds);
 556                 req = fuse_get_req(fc, true);
 557                 if (IS_ERR(req))
 558                         return PTR_ERR(req);
 559         }
 560 
 561         fuse_args_to_req(req, args);
 562 
 563         if (!fuse_request_queue_background(fc, req)) {
 564                 fuse_put_request(fc, req);
 565                 return -ENOTCONN;
 566         }
 567 
 568         return 0;
 569 }
 570 EXPORT_SYMBOL_GPL(fuse_simple_background);
 571 
 572 static int fuse_simple_notify_reply(struct fuse_conn *fc,
 573                                     struct fuse_args *args, u64 unique)
 574 {
 575         struct fuse_req *req;
 576         struct fuse_iqueue *fiq = &fc->iq;
 577         int err = 0;
 578 
 579         req = fuse_get_req(fc, false);
 580         if (IS_ERR(req))
 581                 return PTR_ERR(req);
 582 
 583         __clear_bit(FR_ISREPLY, &req->flags);
 584         req->in.h.unique = unique;
 585 
 586         fuse_args_to_req(req, args);
 587 
 588         spin_lock(&fiq->lock);
 589         if (fiq->connected) {
 590                 queue_request_and_unlock(fiq, req);
 591         } else {
 592                 err = -ENODEV;
 593                 spin_unlock(&fiq->lock);
 594                 fuse_put_request(fc, req);
 595         }
 596 
 597         return err;
 598 }
 599 
 600 /*
 601  * Lock the request.  Up to the next unlock_request() there mustn't be
 602  * anything that could cause a page-fault.  If the request was already
 603  * aborted bail out.
 604  */
 605 static int lock_request(struct fuse_req *req)
 606 {
 607         int err = 0;
 608         if (req) {
 609                 spin_lock(&req->waitq.lock);
 610                 if (test_bit(FR_ABORTED, &req->flags))
 611                         err = -ENOENT;
 612                 else
 613                         set_bit(FR_LOCKED, &req->flags);
 614                 spin_unlock(&req->waitq.lock);
 615         }
 616         return err;
 617 }
 618 
 619 /*
 620  * Unlock request.  If it was aborted while locked, caller is responsible
 621  * for unlocking and ending the request.
 622  */
 623 static int unlock_request(struct fuse_req *req)
 624 {
 625         int err = 0;
 626         if (req) {
 627                 spin_lock(&req->waitq.lock);
 628                 if (test_bit(FR_ABORTED, &req->flags))
 629                         err = -ENOENT;
 630                 else
 631                         clear_bit(FR_LOCKED, &req->flags);
 632                 spin_unlock(&req->waitq.lock);
 633         }
 634         return err;
 635 }
 636 
 637 struct fuse_copy_state {
 638         int write;
 639         struct fuse_req *req;
 640         struct iov_iter *iter;
 641         struct pipe_buffer *pipebufs;
 642         struct pipe_buffer *currbuf;
 643         struct pipe_inode_info *pipe;
 644         unsigned long nr_segs;
 645         struct page *pg;
 646         unsigned len;
 647         unsigned offset;
 648         unsigned move_pages:1;
 649 };
 650 
 651 static void fuse_copy_init(struct fuse_copy_state *cs, int write,
 652                            struct iov_iter *iter)
 653 {
 654         memset(cs, 0, sizeof(*cs));
 655         cs->write = write;
 656         cs->iter = iter;
 657 }
 658 
 659 /* Unmap and put previous page of userspace buffer */
 660 static void fuse_copy_finish(struct fuse_copy_state *cs)
 661 {
 662         if (cs->currbuf) {
 663                 struct pipe_buffer *buf = cs->currbuf;
 664 
 665                 if (cs->write)
 666                         buf->len = PAGE_SIZE - cs->len;
 667                 cs->currbuf = NULL;
 668         } else if (cs->pg) {
 669                 if (cs->write) {
 670                         flush_dcache_page(cs->pg);
 671                         set_page_dirty_lock(cs->pg);
 672                 }
 673                 put_page(cs->pg);
 674         }
 675         cs->pg = NULL;
 676 }
 677 
 678 /*
 679  * Get another pagefull of userspace buffer, and map it to kernel
 680  * address space, and lock request
 681  */
 682 static int fuse_copy_fill(struct fuse_copy_state *cs)
 683 {
 684         struct page *page;
 685         int err;
 686 
 687         err = unlock_request(cs->req);
 688         if (err)
 689                 return err;
 690 
 691         fuse_copy_finish(cs);
 692         if (cs->pipebufs) {
 693                 struct pipe_buffer *buf = cs->pipebufs;
 694 
 695                 if (!cs->write) {
 696                         err = pipe_buf_confirm(cs->pipe, buf);
 697                         if (err)
 698                                 return err;
 699 
 700                         BUG_ON(!cs->nr_segs);
 701                         cs->currbuf = buf;
 702                         cs->pg = buf->page;
 703                         cs->offset = buf->offset;
 704                         cs->len = buf->len;
 705                         cs->pipebufs++;
 706                         cs->nr_segs--;
 707                 } else {
 708                         if (cs->nr_segs == cs->pipe->buffers)
 709                                 return -EIO;
 710 
 711                         page = alloc_page(GFP_HIGHUSER);
 712                         if (!page)
 713                                 return -ENOMEM;
 714 
 715                         buf->page = page;
 716                         buf->offset = 0;
 717                         buf->len = 0;
 718 
 719                         cs->currbuf = buf;
 720                         cs->pg = page;
 721                         cs->offset = 0;
 722                         cs->len = PAGE_SIZE;
 723                         cs->pipebufs++;
 724                         cs->nr_segs++;
 725                 }
 726         } else {
 727                 size_t off;
 728                 err = iov_iter_get_pages(cs->iter, &page, PAGE_SIZE, 1, &off);
 729                 if (err < 0)
 730                         return err;
 731                 BUG_ON(!err);
 732                 cs->len = err;
 733                 cs->offset = off;
 734                 cs->pg = page;
 735                 iov_iter_advance(cs->iter, err);
 736         }
 737 
 738         return lock_request(cs->req);
 739 }
 740 
 741 /* Do as much copy to/from userspace buffer as we can */
 742 static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
 743 {
 744         unsigned ncpy = min(*size, cs->len);
 745         if (val) {
 746                 void *pgaddr = kmap_atomic(cs->pg);
 747                 void *buf = pgaddr + cs->offset;
 748 
 749                 if (cs->write)
 750                         memcpy(buf, *val, ncpy);
 751                 else
 752                         memcpy(*val, buf, ncpy);
 753 
 754                 kunmap_atomic(pgaddr);
 755                 *val += ncpy;
 756         }
 757         *size -= ncpy;
 758         cs->len -= ncpy;
 759         cs->offset += ncpy;
 760         return ncpy;
 761 }
 762 
 763 static int fuse_check_page(struct page *page)
 764 {
 765         if (page_mapcount(page) ||
 766             page->mapping != NULL ||
 767             page_count(page) != 1 ||
 768             (page->flags & PAGE_FLAGS_CHECK_AT_PREP &
 769              ~(1 << PG_locked |
 770                1 << PG_referenced |
 771                1 << PG_uptodate |
 772                1 << PG_lru |
 773                1 << PG_active |
 774                1 << PG_reclaim))) {
 775                 pr_warn("trying to steal weird page\n");
 776                 pr_warn("  page=%p index=%li flags=%08lx, count=%i, mapcount=%i, mapping=%p\n", page, page->index, page->flags, page_count(page), page_mapcount(page), page->mapping);
 777                 return 1;
 778         }
 779         return 0;
 780 }
 781 
 782 static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
 783 {
 784         int err;
 785         struct page *oldpage = *pagep;
 786         struct page *newpage;
 787         struct pipe_buffer *buf = cs->pipebufs;
 788 
 789         err = unlock_request(cs->req);
 790         if (err)
 791                 return err;
 792 
 793         fuse_copy_finish(cs);
 794 
 795         err = pipe_buf_confirm(cs->pipe, buf);
 796         if (err)
 797                 return err;
 798 
 799         BUG_ON(!cs->nr_segs);
 800         cs->currbuf = buf;
 801         cs->len = buf->len;
 802         cs->pipebufs++;
 803         cs->nr_segs--;
 804 
 805         if (cs->len != PAGE_SIZE)
 806                 goto out_fallback;
 807 
 808         if (pipe_buf_steal(cs->pipe, buf) != 0)
 809                 goto out_fallback;
 810 
 811         newpage = buf->page;
 812 
 813         if (!PageUptodate(newpage))
 814                 SetPageUptodate(newpage);
 815 
 816         ClearPageMappedToDisk(newpage);
 817 
 818         if (fuse_check_page(newpage) != 0)
 819                 goto out_fallback_unlock;
 820 
 821         /*
 822          * This is a new and locked page, it shouldn't be mapped or
 823          * have any special flags on it
 824          */
 825         if (WARN_ON(page_mapped(oldpage)))
 826                 goto out_fallback_unlock;
 827         if (WARN_ON(page_has_private(oldpage)))
 828                 goto out_fallback_unlock;
 829         if (WARN_ON(PageDirty(oldpage) || PageWriteback(oldpage)))
 830                 goto out_fallback_unlock;
 831         if (WARN_ON(PageMlocked(oldpage)))
 832                 goto out_fallback_unlock;
 833 
 834         err = replace_page_cache_page(oldpage, newpage, GFP_KERNEL);
 835         if (err) {
 836                 unlock_page(newpage);
 837                 return err;
 838         }
 839 
 840         get_page(newpage);
 841 
 842         if (!(buf->flags & PIPE_BUF_FLAG_LRU))
 843                 lru_cache_add_file(newpage);
 844 
 845         err = 0;
 846         spin_lock(&cs->req->waitq.lock);
 847         if (test_bit(FR_ABORTED, &cs->req->flags))
 848                 err = -ENOENT;
 849         else
 850                 *pagep = newpage;
 851         spin_unlock(&cs->req->waitq.lock);
 852 
 853         if (err) {
 854                 unlock_page(newpage);
 855                 put_page(newpage);
 856                 return err;
 857         }
 858 
 859         unlock_page(oldpage);
 860         put_page(oldpage);
 861         cs->len = 0;
 862 
 863         return 0;
 864 
 865 out_fallback_unlock:
 866         unlock_page(newpage);
 867 out_fallback:
 868         cs->pg = buf->page;
 869         cs->offset = buf->offset;
 870 
 871         err = lock_request(cs->req);
 872         if (err)
 873                 return err;
 874 
 875         return 1;
 876 }
 877 
 878 static int fuse_ref_page(struct fuse_copy_state *cs, struct page *page,
 879                          unsigned offset, unsigned count)
 880 {
 881         struct pipe_buffer *buf;
 882         int err;
 883 
 884         if (cs->nr_segs == cs->pipe->buffers)
 885                 return -EIO;
 886 
 887         err = unlock_request(cs->req);
 888         if (err)
 889                 return err;
 890 
 891         fuse_copy_finish(cs);
 892 
 893         buf = cs->pipebufs;
 894         get_page(page);
 895         buf->page = page;
 896         buf->offset = offset;
 897         buf->len = count;
 898 
 899         cs->pipebufs++;
 900         cs->nr_segs++;
 901         cs->len = 0;
 902 
 903         return 0;
 904 }
 905 
 906 /*
 907  * Copy a page in the request to/from the userspace buffer.  Must be
 908  * done atomically
 909  */
 910 static int fuse_copy_page(struct fuse_copy_state *cs, struct page **pagep,
 911                           unsigned offset, unsigned count, int zeroing)
 912 {
 913         int err;
 914         struct page *page = *pagep;
 915 
 916         if (page && zeroing && count < PAGE_SIZE)
 917                 clear_highpage(page);
 918 
 919         while (count) {
 920                 if (cs->write && cs->pipebufs && page) {
 921                         return fuse_ref_page(cs, page, offset, count);
 922                 } else if (!cs->len) {
 923                         if (cs->move_pages && page &&
 924                             offset == 0 && count == PAGE_SIZE) {
 925                                 err = fuse_try_move_page(cs, pagep);
 926                                 if (err <= 0)
 927                                         return err;
 928                         } else {
 929                                 err = fuse_copy_fill(cs);
 930                                 if (err)
 931                                         return err;
 932                         }
 933                 }
 934                 if (page) {
 935                         void *mapaddr = kmap_atomic(page);
 936                         void *buf = mapaddr + offset;
 937                         offset += fuse_copy_do(cs, &buf, &count);
 938                         kunmap_atomic(mapaddr);
 939                 } else
 940                         offset += fuse_copy_do(cs, NULL, &count);
 941         }
 942         if (page && !cs->write)
 943                 flush_dcache_page(page);
 944         return 0;
 945 }
 946 
 947 /* Copy pages in the request to/from userspace buffer */
 948 static int fuse_copy_pages(struct fuse_copy_state *cs, unsigned nbytes,
 949                            int zeroing)
 950 {
 951         unsigned i;
 952         struct fuse_req *req = cs->req;
 953         struct fuse_args_pages *ap = container_of(req->args, typeof(*ap), args);
 954 
 955 
 956         for (i = 0; i < ap->num_pages && (nbytes || zeroing); i++) {
 957                 int err;
 958                 unsigned int offset = ap->descs[i].offset;
 959                 unsigned int count = min(nbytes, ap->descs[i].length);
 960 
 961                 err = fuse_copy_page(cs, &ap->pages[i], offset, count, zeroing);
 962                 if (err)
 963                         return err;
 964 
 965                 nbytes -= count;
 966         }
 967         return 0;
 968 }
 969 
 970 /* Copy a single argument in the request to/from userspace buffer */
 971 static int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned size)
 972 {
 973         while (size) {
 974                 if (!cs->len) {
 975                         int err = fuse_copy_fill(cs);
 976                         if (err)
 977                                 return err;
 978                 }
 979                 fuse_copy_do(cs, &val, &size);
 980         }
 981         return 0;
 982 }
 983 
 984 /* Copy request arguments to/from userspace buffer */
 985 static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs,
 986                           unsigned argpages, struct fuse_arg *args,
 987                           int zeroing)
 988 {
 989         int err = 0;
 990         unsigned i;
 991 
 992         for (i = 0; !err && i < numargs; i++)  {
 993                 struct fuse_arg *arg = &args[i];
 994                 if (i == numargs - 1 && argpages)
 995                         err = fuse_copy_pages(cs, arg->size, zeroing);
 996                 else
 997                         err = fuse_copy_one(cs, arg->value, arg->size);
 998         }
 999         return err;
1000 }
1001 
1002 static int forget_pending(struct fuse_iqueue *fiq)
1003 {
1004         return fiq->forget_list_head.next != NULL;
1005 }
1006 
1007 static int request_pending(struct fuse_iqueue *fiq)
1008 {
1009         return !list_empty(&fiq->pending) || !list_empty(&fiq->interrupts) ||
1010                 forget_pending(fiq);
1011 }
1012 
1013 /*
1014  * Transfer an interrupt request to userspace
1015  *
1016  * Unlike other requests this is assembled on demand, without a need
1017  * to allocate a separate fuse_req structure.
1018  *
1019  * Called with fiq->lock held, releases it
1020  */
1021 static int fuse_read_interrupt(struct fuse_iqueue *fiq,
1022                                struct fuse_copy_state *cs,
1023                                size_t nbytes, struct fuse_req *req)
1024 __releases(fiq->lock)
1025 {
1026         struct fuse_in_header ih;
1027         struct fuse_interrupt_in arg;
1028         unsigned reqsize = sizeof(ih) + sizeof(arg);
1029         int err;
1030 
1031         list_del_init(&req->intr_entry);
1032         memset(&ih, 0, sizeof(ih));
1033         memset(&arg, 0, sizeof(arg));
1034         ih.len = reqsize;
1035         ih.opcode = FUSE_INTERRUPT;
1036         ih.unique = (req->in.h.unique | FUSE_INT_REQ_BIT);
1037         arg.unique = req->in.h.unique;
1038 
1039         spin_unlock(&fiq->lock);
1040         if (nbytes < reqsize)
1041                 return -EINVAL;
1042 
1043         err = fuse_copy_one(cs, &ih, sizeof(ih));
1044         if (!err)
1045                 err = fuse_copy_one(cs, &arg, sizeof(arg));
1046         fuse_copy_finish(cs);
1047 
1048         return err ? err : reqsize;
1049 }
1050 
1051 struct fuse_forget_link *fuse_dequeue_forget(struct fuse_iqueue *fiq,
1052                                              unsigned int max,
1053                                              unsigned int *countp)
1054 {
1055         struct fuse_forget_link *head = fiq->forget_list_head.next;
1056         struct fuse_forget_link **newhead = &head;
1057         unsigned count;
1058 
1059         for (count = 0; *newhead != NULL && count < max; count++)
1060                 newhead = &(*newhead)->next;
1061 
1062         fiq->forget_list_head.next = *newhead;
1063         *newhead = NULL;
1064         if (fiq->forget_list_head.next == NULL)
1065                 fiq->forget_list_tail = &fiq->forget_list_head;
1066 
1067         if (countp != NULL)
1068                 *countp = count;
1069 
1070         return head;
1071 }
1072 EXPORT_SYMBOL(fuse_dequeue_forget);
1073 
1074 static int fuse_read_single_forget(struct fuse_iqueue *fiq,
1075                                    struct fuse_copy_state *cs,
1076                                    size_t nbytes)
1077 __releases(fiq->lock)
1078 {
1079         int err;
1080         struct fuse_forget_link *forget = fuse_dequeue_forget(fiq, 1, NULL);
1081         struct fuse_forget_in arg = {
1082                 .nlookup = forget->forget_one.nlookup,
1083         };
1084         struct fuse_in_header ih = {
1085                 .opcode = FUSE_FORGET,
1086                 .nodeid = forget->forget_one.nodeid,
1087                 .unique = fuse_get_unique(fiq),
1088                 .len = sizeof(ih) + sizeof(arg),
1089         };
1090 
1091         spin_unlock(&fiq->lock);
1092         kfree(forget);
1093         if (nbytes < ih.len)
1094                 return -EINVAL;
1095 
1096         err = fuse_copy_one(cs, &ih, sizeof(ih));
1097         if (!err)
1098                 err = fuse_copy_one(cs, &arg, sizeof(arg));
1099         fuse_copy_finish(cs);
1100 
1101         if (err)
1102                 return err;
1103 
1104         return ih.len;
1105 }
1106 
1107 static int fuse_read_batch_forget(struct fuse_iqueue *fiq,
1108                                    struct fuse_copy_state *cs, size_t nbytes)
1109 __releases(fiq->lock)
1110 {
1111         int err;
1112         unsigned max_forgets;
1113         unsigned count;
1114         struct fuse_forget_link *head;
1115         struct fuse_batch_forget_in arg = { .count = 0 };
1116         struct fuse_in_header ih = {
1117                 .opcode = FUSE_BATCH_FORGET,
1118                 .unique = fuse_get_unique(fiq),
1119                 .len = sizeof(ih) + sizeof(arg),
1120         };
1121 
1122         if (nbytes < ih.len) {
1123                 spin_unlock(&fiq->lock);
1124                 return -EINVAL;
1125         }
1126 
1127         max_forgets = (nbytes - ih.len) / sizeof(struct fuse_forget_one);
1128         head = fuse_dequeue_forget(fiq, max_forgets, &count);
1129         spin_unlock(&fiq->lock);
1130 
1131         arg.count = count;
1132         ih.len += count * sizeof(struct fuse_forget_one);
1133         err = fuse_copy_one(cs, &ih, sizeof(ih));
1134         if (!err)
1135                 err = fuse_copy_one(cs, &arg, sizeof(arg));
1136 
1137         while (head) {
1138                 struct fuse_forget_link *forget = head;
1139 
1140                 if (!err) {
1141                         err = fuse_copy_one(cs, &forget->forget_one,
1142                                             sizeof(forget->forget_one));
1143                 }
1144                 head = forget->next;
1145                 kfree(forget);
1146         }
1147 
1148         fuse_copy_finish(cs);
1149 
1150         if (err)
1151                 return err;
1152 
1153         return ih.len;
1154 }
1155 
1156 static int fuse_read_forget(struct fuse_conn *fc, struct fuse_iqueue *fiq,
1157                             struct fuse_copy_state *cs,
1158                             size_t nbytes)
1159 __releases(fiq->lock)
1160 {
1161         if (fc->minor < 16 || fiq->forget_list_head.next->next == NULL)
1162                 return fuse_read_single_forget(fiq, cs, nbytes);
1163         else
1164                 return fuse_read_batch_forget(fiq, cs, nbytes);
1165 }
1166 
1167 /*
1168  * Read a single request into the userspace filesystem's buffer.  This
1169  * function waits until a request is available, then removes it from
1170  * the pending list and copies request data to userspace buffer.  If
1171  * no reply is needed (FORGET) or request has been aborted or there
1172  * was an error during the copying then it's finished by calling
1173  * fuse_request_end().  Otherwise add it to the processing list, and set
1174  * the 'sent' flag.
1175  */
1176 static ssize_t fuse_dev_do_read(struct fuse_dev *fud, struct file *file,
1177                                 struct fuse_copy_state *cs, size_t nbytes)
1178 {
1179         ssize_t err;
1180         struct fuse_conn *fc = fud->fc;
1181         struct fuse_iqueue *fiq = &fc->iq;
1182         struct fuse_pqueue *fpq = &fud->pq;
1183         struct fuse_req *req;
1184         struct fuse_args *args;
1185         unsigned reqsize;
1186         unsigned int hash;
1187 
1188         /*
1189          * Require sane minimum read buffer - that has capacity for fixed part
1190          * of any request header + negotiated max_write room for data.
1191          *
1192          * Historically libfuse reserves 4K for fixed header room, but e.g.
1193          * GlusterFS reserves only 80 bytes
1194          *
1195          *      = `sizeof(fuse_in_header) + sizeof(fuse_write_in)`
1196          *
1197          * which is the absolute minimum any sane filesystem should be using
1198          * for header room.
1199          */
1200         if (nbytes < max_t(size_t, FUSE_MIN_READ_BUFFER,
1201                            sizeof(struct fuse_in_header) +
1202                            sizeof(struct fuse_write_in) +
1203                            fc->max_write))
1204                 return -EINVAL;
1205 
1206  restart:
1207         for (;;) {
1208                 spin_lock(&fiq->lock);
1209                 if (!fiq->connected || request_pending(fiq))
1210                         break;
1211                 spin_unlock(&fiq->lock);
1212 
1213                 if (file->f_flags & O_NONBLOCK)
1214                         return -EAGAIN;
1215                 err = wait_event_interruptible_exclusive(fiq->waitq,
1216                                 !fiq->connected || request_pending(fiq));
1217                 if (err)
1218                         return err;
1219         }
1220 
1221         if (!fiq->connected) {
1222                 err = fc->aborted ? -ECONNABORTED : -ENODEV;
1223                 goto err_unlock;
1224         }
1225 
1226         if (!list_empty(&fiq->interrupts)) {
1227                 req = list_entry(fiq->interrupts.next, struct fuse_req,
1228                                  intr_entry);
1229                 return fuse_read_interrupt(fiq, cs, nbytes, req);
1230         }
1231 
1232         if (forget_pending(fiq)) {
1233                 if (list_empty(&fiq->pending) || fiq->forget_batch-- > 0)
1234                         return fuse_read_forget(fc, fiq, cs, nbytes);
1235 
1236                 if (fiq->forget_batch <= -8)
1237                         fiq->forget_batch = 16;
1238         }
1239 
1240         req = list_entry(fiq->pending.next, struct fuse_req, list);
1241         clear_bit(FR_PENDING, &req->flags);
1242         list_del_init(&req->list);
1243         spin_unlock(&fiq->lock);
1244 
1245         args = req->args;
1246         reqsize = req->in.h.len;
1247 
1248         /* If request is too large, reply with an error and restart the read */
1249         if (nbytes < reqsize) {
1250                 req->out.h.error = -EIO;
1251                 /* SETXATTR is special, since it may contain too large data */
1252                 if (args->opcode == FUSE_SETXATTR)
1253                         req->out.h.error = -E2BIG;
1254                 fuse_request_end(fc, req);
1255                 goto restart;
1256         }
1257         spin_lock(&fpq->lock);
1258         list_add(&req->list, &fpq->io);
1259         spin_unlock(&fpq->lock);
1260         cs->req = req;
1261         err = fuse_copy_one(cs, &req->in.h, sizeof(req->in.h));
1262         if (!err)
1263                 err = fuse_copy_args(cs, args->in_numargs, args->in_pages,
1264                                      (struct fuse_arg *) args->in_args, 0);
1265         fuse_copy_finish(cs);
1266         spin_lock(&fpq->lock);
1267         clear_bit(FR_LOCKED, &req->flags);
1268         if (!fpq->connected) {
1269                 err = fc->aborted ? -ECONNABORTED : -ENODEV;
1270                 goto out_end;
1271         }
1272         if (err) {
1273                 req->out.h.error = -EIO;
1274                 goto out_end;
1275         }
1276         if (!test_bit(FR_ISREPLY, &req->flags)) {
1277                 err = reqsize;
1278                 goto out_end;
1279         }
1280         hash = fuse_req_hash(req->in.h.unique);
1281         list_move_tail(&req->list, &fpq->processing[hash]);
1282         __fuse_get_request(req);
1283         set_bit(FR_SENT, &req->flags);
1284         spin_unlock(&fpq->lock);
1285         /* matches barrier in request_wait_answer() */
1286         smp_mb__after_atomic();
1287         if (test_bit(FR_INTERRUPTED, &req->flags))
1288                 queue_interrupt(fiq, req);
1289         fuse_put_request(fc, req);
1290 
1291         return reqsize;
1292 
1293 out_end:
1294         if (!test_bit(FR_PRIVATE, &req->flags))
1295                 list_del_init(&req->list);
1296         spin_unlock(&fpq->lock);
1297         fuse_request_end(fc, req);
1298         return err;
1299 
1300  err_unlock:
1301         spin_unlock(&fiq->lock);
1302         return err;
1303 }
1304 
1305 static int fuse_dev_open(struct inode *inode, struct file *file)
1306 {
1307         /*
1308          * The fuse device's file's private_data is used to hold
1309          * the fuse_conn(ection) when it is mounted, and is used to
1310          * keep track of whether the file has been mounted already.
1311          */
1312         file->private_data = NULL;
1313         return 0;
1314 }
1315 
1316 static ssize_t fuse_dev_read(struct kiocb *iocb, struct iov_iter *to)
1317 {
1318         struct fuse_copy_state cs;
1319         struct file *file = iocb->ki_filp;
1320         struct fuse_dev *fud = fuse_get_dev(file);
1321 
1322         if (!fud)
1323                 return -EPERM;
1324 
1325         if (!iter_is_iovec(to))
1326                 return -EINVAL;
1327 
1328         fuse_copy_init(&cs, 1, to);
1329 
1330         return fuse_dev_do_read(fud, file, &cs, iov_iter_count(to));
1331 }
1332 
1333 static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
1334                                     struct pipe_inode_info *pipe,
1335                                     size_t len, unsigned int flags)
1336 {
1337         int total, ret;
1338         int page_nr = 0;
1339         struct pipe_buffer *bufs;
1340         struct fuse_copy_state cs;
1341         struct fuse_dev *fud = fuse_get_dev(in);
1342 
1343         if (!fud)
1344                 return -EPERM;
1345 
1346         bufs = kvmalloc_array(pipe->buffers, sizeof(struct pipe_buffer),
1347                               GFP_KERNEL);
1348         if (!bufs)
1349                 return -ENOMEM;
1350 
1351         fuse_copy_init(&cs, 1, NULL);
1352         cs.pipebufs = bufs;
1353         cs.pipe = pipe;
1354         ret = fuse_dev_do_read(fud, in, &cs, len);
1355         if (ret < 0)
1356                 goto out;
1357 
1358         if (pipe->nrbufs + cs.nr_segs > pipe->buffers) {
1359                 ret = -EIO;
1360                 goto out;
1361         }
1362 
1363         for (ret = total = 0; page_nr < cs.nr_segs; total += ret) {
1364                 /*
1365                  * Need to be careful about this.  Having buf->ops in module
1366                  * code can Oops if the buffer persists after module unload.
1367                  */
1368                 bufs[page_nr].ops = &nosteal_pipe_buf_ops;
1369                 bufs[page_nr].flags = 0;
1370                 ret = add_to_pipe(pipe, &bufs[page_nr++]);
1371                 if (unlikely(ret < 0))
1372                         break;
1373         }
1374         if (total)
1375                 ret = total;
1376 out:
1377         for (; page_nr < cs.nr_segs; page_nr++)
1378                 put_page(bufs[page_nr].page);
1379 
1380         kvfree(bufs);
1381         return ret;
1382 }
1383 
1384 static int fuse_notify_poll(struct fuse_conn *fc, unsigned int size,
1385                             struct fuse_copy_state *cs)
1386 {
1387         struct fuse_notify_poll_wakeup_out outarg;
1388         int err = -EINVAL;
1389 
1390         if (size != sizeof(outarg))
1391                 goto err;
1392 
1393         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1394         if (err)
1395                 goto err;
1396 
1397         fuse_copy_finish(cs);
1398         return fuse_notify_poll_wakeup(fc, &outarg);
1399 
1400 err:
1401         fuse_copy_finish(cs);
1402         return err;
1403 }
1404 
1405 static int fuse_notify_inval_inode(struct fuse_conn *fc, unsigned int size,
1406                                    struct fuse_copy_state *cs)
1407 {
1408         struct fuse_notify_inval_inode_out outarg;
1409         int err = -EINVAL;
1410 
1411         if (size != sizeof(outarg))
1412                 goto err;
1413 
1414         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1415         if (err)
1416                 goto err;
1417         fuse_copy_finish(cs);
1418 
1419         down_read(&fc->killsb);
1420         err = -ENOENT;
1421         if (fc->sb) {
1422                 err = fuse_reverse_inval_inode(fc->sb, outarg.ino,
1423                                                outarg.off, outarg.len);
1424         }
1425         up_read(&fc->killsb);
1426         return err;
1427 
1428 err:
1429         fuse_copy_finish(cs);
1430         return err;
1431 }
1432 
1433 static int fuse_notify_inval_entry(struct fuse_conn *fc, unsigned int size,
1434                                    struct fuse_copy_state *cs)
1435 {
1436         struct fuse_notify_inval_entry_out outarg;
1437         int err = -ENOMEM;
1438         char *buf;
1439         struct qstr name;
1440 
1441         buf = kzalloc(FUSE_NAME_MAX + 1, GFP_KERNEL);
1442         if (!buf)
1443                 goto err;
1444 
1445         err = -EINVAL;
1446         if (size < sizeof(outarg))
1447                 goto err;
1448 
1449         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1450         if (err)
1451                 goto err;
1452 
1453         err = -ENAMETOOLONG;
1454         if (outarg.namelen > FUSE_NAME_MAX)
1455                 goto err;
1456 
1457         err = -EINVAL;
1458         if (size != sizeof(outarg) + outarg.namelen + 1)
1459                 goto err;
1460 
1461         name.name = buf;
1462         name.len = outarg.namelen;
1463         err = fuse_copy_one(cs, buf, outarg.namelen + 1);
1464         if (err)
1465                 goto err;
1466         fuse_copy_finish(cs);
1467         buf[outarg.namelen] = 0;
1468 
1469         down_read(&fc->killsb);
1470         err = -ENOENT;
1471         if (fc->sb)
1472                 err = fuse_reverse_inval_entry(fc->sb, outarg.parent, 0, &name);
1473         up_read(&fc->killsb);
1474         kfree(buf);
1475         return err;
1476 
1477 err:
1478         kfree(buf);
1479         fuse_copy_finish(cs);
1480         return err;
1481 }
1482 
1483 static int fuse_notify_delete(struct fuse_conn *fc, unsigned int size,
1484                               struct fuse_copy_state *cs)
1485 {
1486         struct fuse_notify_delete_out outarg;
1487         int err = -ENOMEM;
1488         char *buf;
1489         struct qstr name;
1490 
1491         buf = kzalloc(FUSE_NAME_MAX + 1, GFP_KERNEL);
1492         if (!buf)
1493                 goto err;
1494 
1495         err = -EINVAL;
1496         if (size < sizeof(outarg))
1497                 goto err;
1498 
1499         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1500         if (err)
1501                 goto err;
1502 
1503         err = -ENAMETOOLONG;
1504         if (outarg.namelen > FUSE_NAME_MAX)
1505                 goto err;
1506 
1507         err = -EINVAL;
1508         if (size != sizeof(outarg) + outarg.namelen + 1)
1509                 goto err;
1510 
1511         name.name = buf;
1512         name.len = outarg.namelen;
1513         err = fuse_copy_one(cs, buf, outarg.namelen + 1);
1514         if (err)
1515                 goto err;
1516         fuse_copy_finish(cs);
1517         buf[outarg.namelen] = 0;
1518 
1519         down_read(&fc->killsb);
1520         err = -ENOENT;
1521         if (fc->sb)
1522                 err = fuse_reverse_inval_entry(fc->sb, outarg.parent,
1523                                                outarg.child, &name);
1524         up_read(&fc->killsb);
1525         kfree(buf);
1526         return err;
1527 
1528 err:
1529         kfree(buf);
1530         fuse_copy_finish(cs);
1531         return err;
1532 }
1533 
1534 static int fuse_notify_store(struct fuse_conn *fc, unsigned int size,
1535                              struct fuse_copy_state *cs)
1536 {
1537         struct fuse_notify_store_out outarg;
1538         struct inode *inode;
1539         struct address_space *mapping;
1540         u64 nodeid;
1541         int err;
1542         pgoff_t index;
1543         unsigned int offset;
1544         unsigned int num;
1545         loff_t file_size;
1546         loff_t end;
1547 
1548         err = -EINVAL;
1549         if (size < sizeof(outarg))
1550                 goto out_finish;
1551 
1552         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1553         if (err)
1554                 goto out_finish;
1555 
1556         err = -EINVAL;
1557         if (size - sizeof(outarg) != outarg.size)
1558                 goto out_finish;
1559 
1560         nodeid = outarg.nodeid;
1561 
1562         down_read(&fc->killsb);
1563 
1564         err = -ENOENT;
1565         if (!fc->sb)
1566                 goto out_up_killsb;
1567 
1568         inode = ilookup5(fc->sb, nodeid, fuse_inode_eq, &nodeid);
1569         if (!inode)
1570                 goto out_up_killsb;
1571 
1572         mapping = inode->i_mapping;
1573         index = outarg.offset >> PAGE_SHIFT;
1574         offset = outarg.offset & ~PAGE_MASK;
1575         file_size = i_size_read(inode);
1576         end = outarg.offset + outarg.size;
1577         if (end > file_size) {
1578                 file_size = end;
1579                 fuse_write_update_size(inode, file_size);
1580         }
1581 
1582         num = outarg.size;
1583         while (num) {
1584                 struct page *page;
1585                 unsigned int this_num;
1586 
1587                 err = -ENOMEM;
1588                 page = find_or_create_page(mapping, index,
1589                                            mapping_gfp_mask(mapping));
1590                 if (!page)
1591                         goto out_iput;
1592 
1593                 this_num = min_t(unsigned, num, PAGE_SIZE - offset);
1594                 err = fuse_copy_page(cs, &page, offset, this_num, 0);
1595                 if (!err && offset == 0 &&
1596                     (this_num == PAGE_SIZE || file_size == end))
1597                         SetPageUptodate(page);
1598                 unlock_page(page);
1599                 put_page(page);
1600 
1601                 if (err)
1602                         goto out_iput;
1603 
1604                 num -= this_num;
1605                 offset = 0;
1606                 index++;
1607         }
1608 
1609         err = 0;
1610 
1611 out_iput:
1612         iput(inode);
1613 out_up_killsb:
1614         up_read(&fc->killsb);
1615 out_finish:
1616         fuse_copy_finish(cs);
1617         return err;
1618 }
1619 
1620 struct fuse_retrieve_args {
1621         struct fuse_args_pages ap;
1622         struct fuse_notify_retrieve_in inarg;
1623 };
1624 
1625 static void fuse_retrieve_end(struct fuse_conn *fc, struct fuse_args *args,
1626                               int error)
1627 {
1628         struct fuse_retrieve_args *ra =
1629                 container_of(args, typeof(*ra), ap.args);
1630 
1631         release_pages(ra->ap.pages, ra->ap.num_pages);
1632         kfree(ra);
1633 }
1634 
1635 static int fuse_retrieve(struct fuse_conn *fc, struct inode *inode,
1636                          struct fuse_notify_retrieve_out *outarg)
1637 {
1638         int err;
1639         struct address_space *mapping = inode->i_mapping;
1640         pgoff_t index;
1641         loff_t file_size;
1642         unsigned int num;
1643         unsigned int offset;
1644         size_t total_len = 0;
1645         unsigned int num_pages;
1646         struct fuse_retrieve_args *ra;
1647         size_t args_size = sizeof(*ra);
1648         struct fuse_args_pages *ap;
1649         struct fuse_args *args;
1650 
1651         offset = outarg->offset & ~PAGE_MASK;
1652         file_size = i_size_read(inode);
1653 
1654         num = min(outarg->size, fc->max_write);
1655         if (outarg->offset > file_size)
1656                 num = 0;
1657         else if (outarg->offset + num > file_size)
1658                 num = file_size - outarg->offset;
1659 
1660         num_pages = (num + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
1661         num_pages = min(num_pages, fc->max_pages);
1662 
1663         args_size += num_pages * (sizeof(ap->pages[0]) + sizeof(ap->descs[0]));
1664 
1665         ra = kzalloc(args_size, GFP_KERNEL);
1666         if (!ra)
1667                 return -ENOMEM;
1668 
1669         ap = &ra->ap;
1670         ap->pages = (void *) (ra + 1);
1671         ap->descs = (void *) (ap->pages + num_pages);
1672 
1673         args = &ap->args;
1674         args->nodeid = outarg->nodeid;
1675         args->opcode = FUSE_NOTIFY_REPLY;
1676         args->in_numargs = 2;
1677         args->in_pages = true;
1678         args->end = fuse_retrieve_end;
1679 
1680         index = outarg->offset >> PAGE_SHIFT;
1681 
1682         while (num && ap->num_pages < num_pages) {
1683                 struct page *page;
1684                 unsigned int this_num;
1685 
1686                 page = find_get_page(mapping, index);
1687                 if (!page)
1688                         break;
1689 
1690                 this_num = min_t(unsigned, num, PAGE_SIZE - offset);
1691                 ap->pages[ap->num_pages] = page;
1692                 ap->descs[ap->num_pages].offset = offset;
1693                 ap->descs[ap->num_pages].length = this_num;
1694                 ap->num_pages++;
1695 
1696                 offset = 0;
1697                 num -= this_num;
1698                 total_len += this_num;
1699                 index++;
1700         }
1701         ra->inarg.offset = outarg->offset;
1702         ra->inarg.size = total_len;
1703         args->in_args[0].size = sizeof(ra->inarg);
1704         args->in_args[0].value = &ra->inarg;
1705         args->in_args[1].size = total_len;
1706 
1707         err = fuse_simple_notify_reply(fc, args, outarg->notify_unique);
1708         if (err)
1709                 fuse_retrieve_end(fc, args, err);
1710 
1711         return err;
1712 }
1713 
1714 static int fuse_notify_retrieve(struct fuse_conn *fc, unsigned int size,
1715                                 struct fuse_copy_state *cs)
1716 {
1717         struct fuse_notify_retrieve_out outarg;
1718         struct inode *inode;
1719         int err;
1720 
1721         err = -EINVAL;
1722         if (size != sizeof(outarg))
1723                 goto copy_finish;
1724 
1725         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1726         if (err)
1727                 goto copy_finish;
1728 
1729         fuse_copy_finish(cs);
1730 
1731         down_read(&fc->killsb);
1732         err = -ENOENT;
1733         if (fc->sb) {
1734                 u64 nodeid = outarg.nodeid;
1735 
1736                 inode = ilookup5(fc->sb, nodeid, fuse_inode_eq, &nodeid);
1737                 if (inode) {
1738                         err = fuse_retrieve(fc, inode, &outarg);
1739                         iput(inode);
1740                 }
1741         }
1742         up_read(&fc->killsb);
1743 
1744         return err;
1745 
1746 copy_finish:
1747         fuse_copy_finish(cs);
1748         return err;
1749 }
1750 
1751 static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
1752                        unsigned int size, struct fuse_copy_state *cs)
1753 {
1754         /* Don't try to move pages (yet) */
1755         cs->move_pages = 0;
1756 
1757         switch (code) {
1758         case FUSE_NOTIFY_POLL:
1759                 return fuse_notify_poll(fc, size, cs);
1760 
1761         case FUSE_NOTIFY_INVAL_INODE:
1762                 return fuse_notify_inval_inode(fc, size, cs);
1763 
1764         case FUSE_NOTIFY_INVAL_ENTRY:
1765                 return fuse_notify_inval_entry(fc, size, cs);
1766 
1767         case FUSE_NOTIFY_STORE:
1768                 return fuse_notify_store(fc, size, cs);
1769 
1770         case FUSE_NOTIFY_RETRIEVE:
1771                 return fuse_notify_retrieve(fc, size, cs);
1772 
1773         case FUSE_NOTIFY_DELETE:
1774                 return fuse_notify_delete(fc, size, cs);
1775 
1776         default:
1777                 fuse_copy_finish(cs);
1778                 return -EINVAL;
1779         }
1780 }
1781 
1782 /* Look up request on processing list by unique ID */
1783 static struct fuse_req *request_find(struct fuse_pqueue *fpq, u64 unique)
1784 {
1785         unsigned int hash = fuse_req_hash(unique);
1786         struct fuse_req *req;
1787 
1788         list_for_each_entry(req, &fpq->processing[hash], list) {
1789                 if (req->in.h.unique == unique)
1790                         return req;
1791         }
1792         return NULL;
1793 }
1794 
1795 static int copy_out_args(struct fuse_copy_state *cs, struct fuse_args *args,
1796                          unsigned nbytes)
1797 {
1798         unsigned reqsize = sizeof(struct fuse_out_header);
1799 
1800         reqsize += fuse_len_args(args->out_numargs, args->out_args);
1801 
1802         if (reqsize < nbytes || (reqsize > nbytes && !args->out_argvar))
1803                 return -EINVAL;
1804         else if (reqsize > nbytes) {
1805                 struct fuse_arg *lastarg = &args->out_args[args->out_numargs-1];
1806                 unsigned diffsize = reqsize - nbytes;
1807 
1808                 if (diffsize > lastarg->size)
1809                         return -EINVAL;
1810                 lastarg->size -= diffsize;
1811         }
1812         return fuse_copy_args(cs, args->out_numargs, args->out_pages,
1813                               args->out_args, args->page_zeroing);
1814 }
1815 
1816 /*
1817  * Write a single reply to a request.  First the header is copied from
1818  * the write buffer.  The request is then searched on the processing
1819  * list by the unique ID found in the header.  If found, then remove
1820  * it from the list and copy the rest of the buffer to the request.
1821  * The request is finished by calling fuse_request_end().
1822  */
1823 static ssize_t fuse_dev_do_write(struct fuse_dev *fud,
1824                                  struct fuse_copy_state *cs, size_t nbytes)
1825 {
1826         int err;
1827         struct fuse_conn *fc = fud->fc;
1828         struct fuse_pqueue *fpq = &fud->pq;
1829         struct fuse_req *req;
1830         struct fuse_out_header oh;
1831 
1832         err = -EINVAL;
1833         if (nbytes < sizeof(struct fuse_out_header))
1834                 goto out;
1835 
1836         err = fuse_copy_one(cs, &oh, sizeof(oh));
1837         if (err)
1838                 goto copy_finish;
1839 
1840         err = -EINVAL;
1841         if (oh.len != nbytes)
1842                 goto copy_finish;
1843 
1844         /*
1845          * Zero oh.unique indicates unsolicited notification message
1846          * and error contains notification code.
1847          */
1848         if (!oh.unique) {
1849                 err = fuse_notify(fc, oh.error, nbytes - sizeof(oh), cs);
1850                 goto out;
1851         }
1852 
1853         err = -EINVAL;
1854         if (oh.error <= -1000 || oh.error > 0)
1855                 goto copy_finish;
1856 
1857         spin_lock(&fpq->lock);
1858         req = NULL;
1859         if (fpq->connected)
1860                 req = request_find(fpq, oh.unique & ~FUSE_INT_REQ_BIT);
1861 
1862         err = -ENOENT;
1863         if (!req) {
1864                 spin_unlock(&fpq->lock);
1865                 goto copy_finish;
1866         }
1867 
1868         /* Is it an interrupt reply ID? */
1869         if (oh.unique & FUSE_INT_REQ_BIT) {
1870                 __fuse_get_request(req);
1871                 spin_unlock(&fpq->lock);
1872 
1873                 err = 0;
1874                 if (nbytes != sizeof(struct fuse_out_header))
1875                         err = -EINVAL;
1876                 else if (oh.error == -ENOSYS)
1877                         fc->no_interrupt = 1;
1878                 else if (oh.error == -EAGAIN)
1879                         err = queue_interrupt(&fc->iq, req);
1880 
1881                 fuse_put_request(fc, req);
1882 
1883                 goto copy_finish;
1884         }
1885 
1886         clear_bit(FR_SENT, &req->flags);
1887         list_move(&req->list, &fpq->io);
1888         req->out.h = oh;
1889         set_bit(FR_LOCKED, &req->flags);
1890         spin_unlock(&fpq->lock);
1891         cs->req = req;
1892         if (!req->args->page_replace)
1893                 cs->move_pages = 0;
1894 
1895         if (oh.error)
1896                 err = nbytes != sizeof(oh) ? -EINVAL : 0;
1897         else
1898                 err = copy_out_args(cs, req->args, nbytes);
1899         fuse_copy_finish(cs);
1900 
1901         spin_lock(&fpq->lock);
1902         clear_bit(FR_LOCKED, &req->flags);
1903         if (!fpq->connected)
1904                 err = -ENOENT;
1905         else if (err)
1906                 req->out.h.error = -EIO;
1907         if (!test_bit(FR_PRIVATE, &req->flags))
1908                 list_del_init(&req->list);
1909         spin_unlock(&fpq->lock);
1910 
1911         fuse_request_end(fc, req);
1912 out:
1913         return err ? err : nbytes;
1914 
1915 copy_finish:
1916         fuse_copy_finish(cs);
1917         goto out;
1918 }
1919 
1920 static ssize_t fuse_dev_write(struct kiocb *iocb, struct iov_iter *from)
1921 {
1922         struct fuse_copy_state cs;
1923         struct fuse_dev *fud = fuse_get_dev(iocb->ki_filp);
1924 
1925         if (!fud)
1926                 return -EPERM;
1927 
1928         if (!iter_is_iovec(from))
1929                 return -EINVAL;
1930 
1931         fuse_copy_init(&cs, 0, from);
1932 
1933         return fuse_dev_do_write(fud, &cs, iov_iter_count(from));
1934 }
1935 
1936 static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
1937                                      struct file *out, loff_t *ppos,
1938                                      size_t len, unsigned int flags)
1939 {
1940         unsigned nbuf;
1941         unsigned idx;
1942         struct pipe_buffer *bufs;
1943         struct fuse_copy_state cs;
1944         struct fuse_dev *fud;
1945         size_t rem;
1946         ssize_t ret;
1947 
1948         fud = fuse_get_dev(out);
1949         if (!fud)
1950                 return -EPERM;
1951 
1952         pipe_lock(pipe);
1953 
1954         bufs = kvmalloc_array(pipe->nrbufs, sizeof(struct pipe_buffer),
1955                               GFP_KERNEL);
1956         if (!bufs) {
1957                 pipe_unlock(pipe);
1958                 return -ENOMEM;
1959         }
1960 
1961         nbuf = 0;
1962         rem = 0;
1963         for (idx = 0; idx < pipe->nrbufs && rem < len; idx++)
1964                 rem += pipe->bufs[(pipe->curbuf + idx) & (pipe->buffers - 1)].len;
1965 
1966         ret = -EINVAL;
1967         if (rem < len)
1968                 goto out_free;
1969 
1970         rem = len;
1971         while (rem) {
1972                 struct pipe_buffer *ibuf;
1973                 struct pipe_buffer *obuf;
1974 
1975                 BUG_ON(nbuf >= pipe->buffers);
1976                 BUG_ON(!pipe->nrbufs);
1977                 ibuf = &pipe->bufs[pipe->curbuf];
1978                 obuf = &bufs[nbuf];
1979 
1980                 if (rem >= ibuf->len) {
1981                         *obuf = *ibuf;
1982                         ibuf->ops = NULL;
1983                         pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
1984                         pipe->nrbufs--;
1985                 } else {
1986                         if (!pipe_buf_get(pipe, ibuf))
1987                                 goto out_free;
1988 
1989                         *obuf = *ibuf;
1990                         obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1991                         obuf->len = rem;
1992                         ibuf->offset += obuf->len;
1993                         ibuf->len -= obuf->len;
1994                 }
1995                 nbuf++;
1996                 rem -= obuf->len;
1997         }
1998         pipe_unlock(pipe);
1999 
2000         fuse_copy_init(&cs, 0, NULL);
2001         cs.pipebufs = bufs;
2002         cs.nr_segs = nbuf;
2003         cs.pipe = pipe;
2004 
2005         if (flags & SPLICE_F_MOVE)
2006                 cs.move_pages = 1;
2007 
2008         ret = fuse_dev_do_write(fud, &cs, len);
2009 
2010         pipe_lock(pipe);
2011 out_free:
2012         for (idx = 0; idx < nbuf; idx++)
2013                 pipe_buf_release(pipe, &bufs[idx]);
2014         pipe_unlock(pipe);
2015 
2016         kvfree(bufs);
2017         return ret;
2018 }
2019 
2020 static __poll_t fuse_dev_poll(struct file *file, poll_table *wait)
2021 {
2022         __poll_t mask = EPOLLOUT | EPOLLWRNORM;
2023         struct fuse_iqueue *fiq;
2024         struct fuse_dev *fud = fuse_get_dev(file);
2025 
2026         if (!fud)
2027                 return EPOLLERR;
2028 
2029         fiq = &fud->fc->iq;
2030         poll_wait(file, &fiq->waitq, wait);
2031 
2032         spin_lock(&fiq->lock);
2033         if (!fiq->connected)
2034                 mask = EPOLLERR;
2035         else if (request_pending(fiq))
2036                 mask |= EPOLLIN | EPOLLRDNORM;
2037         spin_unlock(&fiq->lock);
2038 
2039         return mask;
2040 }
2041 
2042 /* Abort all requests on the given list (pending or processing) */
2043 static void end_requests(struct fuse_conn *fc, struct list_head *head)
2044 {
2045         while (!list_empty(head)) {
2046                 struct fuse_req *req;
2047                 req = list_entry(head->next, struct fuse_req, list);
2048                 req->out.h.error = -ECONNABORTED;
2049                 clear_bit(FR_SENT, &req->flags);
2050                 list_del_init(&req->list);
2051                 fuse_request_end(fc, req);
2052         }
2053 }
2054 
2055 static void end_polls(struct fuse_conn *fc)
2056 {
2057         struct rb_node *p;
2058 
2059         p = rb_first(&fc->polled_files);
2060 
2061         while (p) {
2062                 struct fuse_file *ff;
2063                 ff = rb_entry(p, struct fuse_file, polled_node);
2064                 wake_up_interruptible_all(&ff->poll_wait);
2065 
2066                 p = rb_next(p);
2067         }
2068 }
2069 
2070 /*
2071  * Abort all requests.
2072  *
2073  * Emergency exit in case of a malicious or accidental deadlock, or just a hung
2074  * filesystem.
2075  *
2076  * The same effect is usually achievable through killing the filesystem daemon
2077  * and all users of the filesystem.  The exception is the combination of an
2078  * asynchronous request and the tricky deadlock (see
2079  * Documentation/filesystems/fuse.txt).
2080  *
2081  * Aborting requests under I/O goes as follows: 1: Separate out unlocked
2082  * requests, they should be finished off immediately.  Locked requests will be
2083  * finished after unlock; see unlock_request(). 2: Finish off the unlocked
2084  * requests.  It is possible that some request will finish before we can.  This
2085  * is OK, the request will in that case be removed from the list before we touch
2086  * it.
2087  */
2088 void fuse_abort_conn(struct fuse_conn *fc)
2089 {
2090         struct fuse_iqueue *fiq = &fc->iq;
2091 
2092         spin_lock(&fc->lock);
2093         if (fc->connected) {
2094                 struct fuse_dev *fud;
2095                 struct fuse_req *req, *next;
2096                 LIST_HEAD(to_end);
2097                 unsigned int i;
2098 
2099                 /* Background queuing checks fc->connected under bg_lock */
2100                 spin_lock(&fc->bg_lock);
2101                 fc->connected = 0;
2102                 spin_unlock(&fc->bg_lock);
2103 
2104                 fuse_set_initialized(fc);
2105                 list_for_each_entry(fud, &fc->devices, entry) {
2106                         struct fuse_pqueue *fpq = &fud->pq;
2107 
2108                         spin_lock(&fpq->lock);
2109                         fpq->connected = 0;
2110                         list_for_each_entry_safe(req, next, &fpq->io, list) {
2111                                 req->out.h.error = -ECONNABORTED;
2112                                 spin_lock(&req->waitq.lock);
2113                                 set_bit(FR_ABORTED, &req->flags);
2114                                 if (!test_bit(FR_LOCKED, &req->flags)) {
2115                                         set_bit(FR_PRIVATE, &req->flags);
2116                                         __fuse_get_request(req);
2117                                         list_move(&req->list, &to_end);
2118                                 }
2119                                 spin_unlock(&req->waitq.lock);
2120                         }
2121                         for (i = 0; i < FUSE_PQ_HASH_SIZE; i++)
2122                                 list_splice_tail_init(&fpq->processing[i],
2123                                                       &to_end);
2124                         spin_unlock(&fpq->lock);
2125                 }
2126                 spin_lock(&fc->bg_lock);
2127                 fc->blocked = 0;
2128                 fc->max_background = UINT_MAX;
2129                 flush_bg_queue(fc);
2130                 spin_unlock(&fc->bg_lock);
2131 
2132                 spin_lock(&fiq->lock);
2133                 fiq->connected = 0;
2134                 list_for_each_entry(req, &fiq->pending, list)
2135                         clear_bit(FR_PENDING, &req->flags);
2136                 list_splice_tail_init(&fiq->pending, &to_end);
2137                 while (forget_pending(fiq))
2138                         kfree(fuse_dequeue_forget(fiq, 1, NULL));
2139                 wake_up_all(&fiq->waitq);
2140                 spin_unlock(&fiq->lock);
2141                 kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
2142                 end_polls(fc);
2143                 wake_up_all(&fc->blocked_waitq);
2144                 spin_unlock(&fc->lock);
2145 
2146                 end_requests(fc, &to_end);
2147         } else {
2148                 spin_unlock(&fc->lock);
2149         }
2150 }
2151 EXPORT_SYMBOL_GPL(fuse_abort_conn);
2152 
2153 void fuse_wait_aborted(struct fuse_conn *fc)
2154 {
2155         /* matches implicit memory barrier in fuse_drop_waiting() */
2156         smp_mb();
2157         wait_event(fc->blocked_waitq, atomic_read(&fc->num_waiting) == 0);
2158 }
2159 
2160 int fuse_dev_release(struct inode *inode, struct file *file)
2161 {
2162         struct fuse_dev *fud = fuse_get_dev(file);
2163 
2164         if (fud) {
2165                 struct fuse_conn *fc = fud->fc;
2166                 struct fuse_pqueue *fpq = &fud->pq;
2167                 LIST_HEAD(to_end);
2168                 unsigned int i;
2169 
2170                 spin_lock(&fpq->lock);
2171                 WARN_ON(!list_empty(&fpq->io));
2172                 for (i = 0; i < FUSE_PQ_HASH_SIZE; i++)
2173                         list_splice_init(&fpq->processing[i], &to_end);
2174                 spin_unlock(&fpq->lock);
2175 
2176                 end_requests(fc, &to_end);
2177 
2178                 /* Are we the last open device? */
2179                 if (atomic_dec_and_test(&fc->dev_count)) {
2180                         WARN_ON(fc->iq.fasync != NULL);
2181                         fuse_abort_conn(fc);
2182                 }
2183                 fuse_dev_free(fud);
2184         }
2185         return 0;
2186 }
2187 EXPORT_SYMBOL_GPL(fuse_dev_release);
2188 
2189 static int fuse_dev_fasync(int fd, struct file *file, int on)
2190 {
2191         struct fuse_dev *fud = fuse_get_dev(file);
2192 
2193         if (!fud)
2194                 return -EPERM;
2195 
2196         /* No locking - fasync_helper does its own locking */
2197         return fasync_helper(fd, file, on, &fud->fc->iq.fasync);
2198 }
2199 
2200 static int fuse_device_clone(struct fuse_conn *fc, struct file *new)
2201 {
2202         struct fuse_dev *fud;
2203 
2204         if (new->private_data)
2205                 return -EINVAL;
2206 
2207         fud = fuse_dev_alloc_install(fc);
2208         if (!fud)
2209                 return -ENOMEM;
2210 
2211         new->private_data = fud;
2212         atomic_inc(&fc->dev_count);
2213 
2214         return 0;
2215 }
2216 
2217 static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
2218                            unsigned long arg)
2219 {
2220         int err = -ENOTTY;
2221 
2222         if (cmd == FUSE_DEV_IOC_CLONE) {
2223                 int oldfd;
2224 
2225                 err = -EFAULT;
2226                 if (!get_user(oldfd, (__u32 __user *) arg)) {
2227                         struct file *old = fget(oldfd);
2228 
2229                         err = -EINVAL;
2230                         if (old) {
2231                                 struct fuse_dev *fud = NULL;
2232 
2233                                 /*
2234                                  * Check against file->f_op because CUSE
2235                                  * uses the same ioctl handler.
2236                                  */
2237                                 if (old->f_op == file->f_op &&
2238                                     old->f_cred->user_ns == file->f_cred->user_ns)
2239                                         fud = fuse_get_dev(old);
2240 
2241                                 if (fud) {
2242                                         mutex_lock(&fuse_mutex);
2243                                         err = fuse_device_clone(fud->fc, file);
2244                                         mutex_unlock(&fuse_mutex);
2245                                 }
2246                                 fput(old);
2247                         }
2248                 }
2249         }
2250         return err;
2251 }
2252 
2253 const struct file_operations fuse_dev_operations = {
2254         .owner          = THIS_MODULE,
2255         .open           = fuse_dev_open,
2256         .llseek         = no_llseek,
2257         .read_iter      = fuse_dev_read,
2258         .splice_read    = fuse_dev_splice_read,
2259         .write_iter     = fuse_dev_write,
2260         .splice_write   = fuse_dev_splice_write,
2261         .poll           = fuse_dev_poll,
2262         .release        = fuse_dev_release,
2263         .fasync         = fuse_dev_fasync,
2264         .unlocked_ioctl = fuse_dev_ioctl,
2265         .compat_ioctl   = fuse_dev_ioctl,
2266 };
2267 EXPORT_SYMBOL_GPL(fuse_dev_operations);
2268 
2269 static struct miscdevice fuse_miscdevice = {
2270         .minor = FUSE_MINOR,
2271         .name  = "fuse",
2272         .fops = &fuse_dev_operations,
2273 };
2274 
2275 int __init fuse_dev_init(void)
2276 {
2277         int err = -ENOMEM;
2278         fuse_req_cachep = kmem_cache_create("fuse_request",
2279                                             sizeof(struct fuse_req),
2280                                             0, 0, NULL);
2281         if (!fuse_req_cachep)
2282                 goto out;
2283 
2284         err = misc_register(&fuse_miscdevice);
2285         if (err)
2286                 goto out_cache_clean;
2287 
2288         return 0;
2289 
2290  out_cache_clean:
2291         kmem_cache_destroy(fuse_req_cachep);
2292  out:
2293         return err;
2294 }
2295 
2296 void fuse_dev_cleanup(void)
2297 {
2298         misc_deregister(&fuse_miscdevice);
2299         kmem_cache_destroy(fuse_req_cachep);
2300 }
/* [<][>][^][v][top][bottom][index][help] */
root/fs/fuse/dev.c

DEFINITIONS
