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Linux/fs/fuse/dev.c

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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 #include <linux/pipe_fs_i.h>
 20 #include <linux/swap.h>
 21 #include <linux/splice.h>
 22 #include <linux/aio.h>
 23 
 24 MODULE_ALIAS_MISCDEV(FUSE_MINOR);
 25 MODULE_ALIAS("devname:fuse");
 26 
 27 static struct kmem_cache *fuse_req_cachep;
 28 
 29 static struct fuse_conn *fuse_get_conn(struct file *file)
 30 {
 31         /*
 32          * Lockless access is OK, because file->private data is set
 33          * once during mount and is valid until the file is released.
 34          */
 35         return file->private_data;
 36 }
 37 
 38 static void fuse_request_init(struct fuse_req *req, struct page **pages,
 39                               struct fuse_page_desc *page_descs,
 40                               unsigned npages)
 41 {
 42         memset(req, 0, sizeof(*req));
 43         memset(pages, 0, sizeof(*pages) * npages);
 44         memset(page_descs, 0, sizeof(*page_descs) * npages);
 45         INIT_LIST_HEAD(&req->list);
 46         INIT_LIST_HEAD(&req->intr_entry);
 47         init_waitqueue_head(&req->waitq);
 48         atomic_set(&req->count, 1);
 49         req->pages = pages;
 50         req->page_descs = page_descs;
 51         req->max_pages = npages;
 52 }
 53 
 54 static struct fuse_req *__fuse_request_alloc(unsigned npages, gfp_t flags)
 55 {
 56         struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, flags);
 57         if (req) {
 58                 struct page **pages;
 59                 struct fuse_page_desc *page_descs;
 60 
 61                 if (npages <= FUSE_REQ_INLINE_PAGES) {
 62                         pages = req->inline_pages;
 63                         page_descs = req->inline_page_descs;
 64                 } else {
 65                         pages = kmalloc(sizeof(struct page *) * npages, flags);
 66                         page_descs = kmalloc(sizeof(struct fuse_page_desc) *
 67                                              npages, flags);
 68                 }
 69 
 70                 if (!pages || !page_descs) {
 71                         kfree(pages);
 72                         kfree(page_descs);
 73                         kmem_cache_free(fuse_req_cachep, req);
 74                         return NULL;
 75                 }
 76 
 77                 fuse_request_init(req, pages, page_descs, npages);
 78         }
 79         return req;
 80 }
 81 
 82 struct fuse_req *fuse_request_alloc(unsigned npages)
 83 {
 84         return __fuse_request_alloc(npages, GFP_KERNEL);
 85 }
 86 EXPORT_SYMBOL_GPL(fuse_request_alloc);
 87 
 88 struct fuse_req *fuse_request_alloc_nofs(unsigned npages)
 89 {
 90         return __fuse_request_alloc(npages, GFP_NOFS);
 91 }
 92 
 93 void fuse_request_free(struct fuse_req *req)
 94 {
 95         if (req->pages != req->inline_pages) {
 96                 kfree(req->pages);
 97                 kfree(req->page_descs);
 98         }
 99         kmem_cache_free(fuse_req_cachep, req);
100 }
101 
102 static void block_sigs(sigset_t *oldset)
103 {
104         sigset_t mask;
105 
106         siginitsetinv(&mask, sigmask(SIGKILL));
107         sigprocmask(SIG_BLOCK, &mask, oldset);
108 }
109 
110 static void restore_sigs(sigset_t *oldset)
111 {
112         sigprocmask(SIG_SETMASK, oldset, NULL);
113 }
114 
115 void __fuse_get_request(struct fuse_req *req)
116 {
117         atomic_inc(&req->count);
118 }
119 
120 /* Must be called with > 1 refcount */
121 static void __fuse_put_request(struct fuse_req *req)
122 {
123         BUG_ON(atomic_read(&req->count) < 2);
124         atomic_dec(&req->count);
125 }
126 
127 static void fuse_req_init_context(struct fuse_req *req)
128 {
129         req->in.h.uid = from_kuid_munged(&init_user_ns, current_fsuid());
130         req->in.h.gid = from_kgid_munged(&init_user_ns, current_fsgid());
131         req->in.h.pid = current->pid;
132 }
133 
134 static bool fuse_block_alloc(struct fuse_conn *fc, bool for_background)
135 {
136         return !fc->initialized || (for_background && fc->blocked);
137 }
138 
139 static struct fuse_req *__fuse_get_req(struct fuse_conn *fc, unsigned npages,
140                                        bool for_background)
141 {
142         struct fuse_req *req;
143         int err;
144         atomic_inc(&fc->num_waiting);
145 
146         if (fuse_block_alloc(fc, for_background)) {
147                 sigset_t oldset;
148                 int intr;
149 
150                 block_sigs(&oldset);
151                 intr = wait_event_interruptible_exclusive(fc->blocked_waitq,
152                                 !fuse_block_alloc(fc, for_background));
153                 restore_sigs(&oldset);
154                 err = -EINTR;
155                 if (intr)
156                         goto out;
157         }
158 
159         err = -ENOTCONN;
160         if (!fc->connected)
161                 goto out;
162 
163         req = fuse_request_alloc(npages);
164         err = -ENOMEM;
165         if (!req) {
166                 if (for_background)
167                         wake_up(&fc->blocked_waitq);
168                 goto out;
169         }
170 
171         fuse_req_init_context(req);
172         req->waiting = 1;
173         req->background = for_background;
174         return req;
175 
176  out:
177         atomic_dec(&fc->num_waiting);
178         return ERR_PTR(err);
179 }
180 
181 struct fuse_req *fuse_get_req(struct fuse_conn *fc, unsigned npages)
182 {
183         return __fuse_get_req(fc, npages, false);
184 }
185 EXPORT_SYMBOL_GPL(fuse_get_req);
186 
187 struct fuse_req *fuse_get_req_for_background(struct fuse_conn *fc,
188                                              unsigned npages)
189 {
190         return __fuse_get_req(fc, npages, true);
191 }
192 EXPORT_SYMBOL_GPL(fuse_get_req_for_background);
193 
194 /*
195  * Return request in fuse_file->reserved_req.  However that may
196  * currently be in use.  If that is the case, wait for it to become
197  * available.
198  */
199 static struct fuse_req *get_reserved_req(struct fuse_conn *fc,
200                                          struct file *file)
201 {
202         struct fuse_req *req = NULL;
203         struct fuse_file *ff = file->private_data;
204 
205         do {
206                 wait_event(fc->reserved_req_waitq, ff->reserved_req);
207                 spin_lock(&fc->lock);
208                 if (ff->reserved_req) {
209                         req = ff->reserved_req;
210                         ff->reserved_req = NULL;
211                         req->stolen_file = get_file(file);
212                 }
213                 spin_unlock(&fc->lock);
214         } while (!req);
215 
216         return req;
217 }
218 
219 /*
220  * Put stolen request back into fuse_file->reserved_req
221  */
222 static void put_reserved_req(struct fuse_conn *fc, struct fuse_req *req)
223 {
224         struct file *file = req->stolen_file;
225         struct fuse_file *ff = file->private_data;
226 
227         spin_lock(&fc->lock);
228         fuse_request_init(req, req->pages, req->page_descs, req->max_pages);
229         BUG_ON(ff->reserved_req);
230         ff->reserved_req = req;
231         wake_up_all(&fc->reserved_req_waitq);
232         spin_unlock(&fc->lock);
233         fput(file);
234 }
235 
236 /*
237  * Gets a requests for a file operation, always succeeds
238  *
239  * This is used for sending the FLUSH request, which must get to
240  * userspace, due to POSIX locks which may need to be unlocked.
241  *
242  * If allocation fails due to OOM, use the reserved request in
243  * fuse_file.
244  *
245  * This is very unlikely to deadlock accidentally, since the
246  * filesystem should not have it's own file open.  If deadlock is
247  * intentional, it can still be broken by "aborting" the filesystem.
248  */
249 struct fuse_req *fuse_get_req_nofail_nopages(struct fuse_conn *fc,
250                                              struct file *file)
251 {
252         struct fuse_req *req;
253 
254         atomic_inc(&fc->num_waiting);
255         wait_event(fc->blocked_waitq, fc->initialized);
256         req = fuse_request_alloc(0);
257         if (!req)
258                 req = get_reserved_req(fc, file);
259 
260         fuse_req_init_context(req);
261         req->waiting = 1;
262         req->background = 0;
263         return req;
264 }
265 
266 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
267 {
268         if (atomic_dec_and_test(&req->count)) {
269                 if (unlikely(req->background)) {
270                         /*
271                          * We get here in the unlikely case that a background
272                          * request was allocated but not sent
273                          */
274                         spin_lock(&fc->lock);
275                         if (!fc->blocked)
276                                 wake_up(&fc->blocked_waitq);
277                         spin_unlock(&fc->lock);
278                 }
279 
280                 if (req->waiting)
281                         atomic_dec(&fc->num_waiting);
282 
283                 if (req->stolen_file)
284                         put_reserved_req(fc, req);
285                 else
286                         fuse_request_free(req);
287         }
288 }
289 EXPORT_SYMBOL_GPL(fuse_put_request);
290 
291 static unsigned len_args(unsigned numargs, struct fuse_arg *args)
292 {
293         unsigned nbytes = 0;
294         unsigned i;
295 
296         for (i = 0; i < numargs; i++)
297                 nbytes += args[i].size;
298 
299         return nbytes;
300 }
301 
302 static u64 fuse_get_unique(struct fuse_conn *fc)
303 {
304         fc->reqctr++;
305         /* zero is special */
306         if (fc->reqctr == 0)
307                 fc->reqctr = 1;
308 
309         return fc->reqctr;
310 }
311 
312 static void queue_request(struct fuse_conn *fc, struct fuse_req *req)
313 {
314         req->in.h.len = sizeof(struct fuse_in_header) +
315                 len_args(req->in.numargs, (struct fuse_arg *) req->in.args);
316         list_add_tail(&req->list, &fc->pending);
317         req->state = FUSE_REQ_PENDING;
318         if (!req->waiting) {
319                 req->waiting = 1;
320                 atomic_inc(&fc->num_waiting);
321         }
322         wake_up(&fc->waitq);
323         kill_fasync(&fc->fasync, SIGIO, POLL_IN);
324 }
325 
326 void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
327                        u64 nodeid, u64 nlookup)
328 {
329         forget->forget_one.nodeid = nodeid;
330         forget->forget_one.nlookup = nlookup;
331 
332         spin_lock(&fc->lock);
333         if (fc->connected) {
334                 fc->forget_list_tail->next = forget;
335                 fc->forget_list_tail = forget;
336                 wake_up(&fc->waitq);
337                 kill_fasync(&fc->fasync, SIGIO, POLL_IN);
338         } else {
339                 kfree(forget);
340         }
341         spin_unlock(&fc->lock);
342 }
343 
344 static void flush_bg_queue(struct fuse_conn *fc)
345 {
346         while (fc->active_background < fc->max_background &&
347                !list_empty(&fc->bg_queue)) {
348                 struct fuse_req *req;
349 
350                 req = list_entry(fc->bg_queue.next, struct fuse_req, list);
351                 list_del(&req->list);
352                 fc->active_background++;
353                 req->in.h.unique = fuse_get_unique(fc);
354                 queue_request(fc, req);
355         }
356 }
357 
358 /*
359  * This function is called when a request is finished.  Either a reply
360  * has arrived or it was aborted (and not yet sent) or some error
361  * occurred during communication with userspace, or the device file
362  * was closed.  The requester thread is woken up (if still waiting),
363  * the 'end' callback is called if given, else the reference to the
364  * request is released
365  *
366  * Called with fc->lock, unlocks it
367  */
368 static void request_end(struct fuse_conn *fc, struct fuse_req *req)
369 __releases(fc->lock)
370 {
371         void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
372         req->end = NULL;
373         list_del(&req->list);
374         list_del(&req->intr_entry);
375         req->state = FUSE_REQ_FINISHED;
376         if (req->background) {
377                 req->background = 0;
378 
379                 if (fc->num_background == fc->max_background)
380                         fc->blocked = 0;
381 
382                 /* Wake up next waiter, if any */
383                 if (!fc->blocked && waitqueue_active(&fc->blocked_waitq))
384                         wake_up(&fc->blocked_waitq);
385 
386                 if (fc->num_background == fc->congestion_threshold &&
387                     fc->connected && fc->bdi_initialized) {
388                         clear_bdi_congested(&fc->bdi, BLK_RW_SYNC);
389                         clear_bdi_congested(&fc->bdi, BLK_RW_ASYNC);
390                 }
391                 fc->num_background--;
392                 fc->active_background--;
393                 flush_bg_queue(fc);
394         }
395         spin_unlock(&fc->lock);
396         wake_up(&req->waitq);
397         if (end)
398                 end(fc, req);
399         fuse_put_request(fc, req);
400 }
401 
402 static void wait_answer_interruptible(struct fuse_conn *fc,
403                                       struct fuse_req *req)
404 __releases(fc->lock)
405 __acquires(fc->lock)
406 {
407         if (signal_pending(current))
408                 return;
409 
410         spin_unlock(&fc->lock);
411         wait_event_interruptible(req->waitq, req->state == FUSE_REQ_FINISHED);
412         spin_lock(&fc->lock);
413 }
414 
415 static void queue_interrupt(struct fuse_conn *fc, struct fuse_req *req)
416 {
417         list_add_tail(&req->intr_entry, &fc->interrupts);
418         wake_up(&fc->waitq);
419         kill_fasync(&fc->fasync, SIGIO, POLL_IN);
420 }
421 
422 static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
423 __releases(fc->lock)
424 __acquires(fc->lock)
425 {
426         if (!fc->no_interrupt) {
427                 /* Any signal may interrupt this */
428                 wait_answer_interruptible(fc, req);
429 
430                 if (req->aborted)
431                         goto aborted;
432                 if (req->state == FUSE_REQ_FINISHED)
433                         return;
434 
435                 req->interrupted = 1;
436                 if (req->state == FUSE_REQ_SENT)
437                         queue_interrupt(fc, req);
438         }
439 
440         if (!req->force) {
441                 sigset_t oldset;
442 
443                 /* Only fatal signals may interrupt this */
444                 block_sigs(&oldset);
445                 wait_answer_interruptible(fc, req);
446                 restore_sigs(&oldset);
447 
448                 if (req->aborted)
449                         goto aborted;
450                 if (req->state == FUSE_REQ_FINISHED)
451                         return;
452 
453                 /* Request is not yet in userspace, bail out */
454                 if (req->state == FUSE_REQ_PENDING) {
455                         list_del(&req->list);
456                         __fuse_put_request(req);
457                         req->out.h.error = -EINTR;
458                         return;
459                 }
460         }
461 
462         /*
463          * Either request is already in userspace, or it was forced.
464          * Wait it out.
465          */
466         spin_unlock(&fc->lock);
467         wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
468         spin_lock(&fc->lock);
469 
470         if (!req->aborted)
471                 return;
472 
473  aborted:
474         BUG_ON(req->state != FUSE_REQ_FINISHED);
475         if (req->locked) {
476                 /* This is uninterruptible sleep, because data is
477                    being copied to/from the buffers of req.  During
478                    locked state, there mustn't be any filesystem
479                    operation (e.g. page fault), since that could lead
480                    to deadlock */
481                 spin_unlock(&fc->lock);
482                 wait_event(req->waitq, !req->locked);
483                 spin_lock(&fc->lock);
484         }
485 }
486 
487 static void __fuse_request_send(struct fuse_conn *fc, struct fuse_req *req)
488 {
489         BUG_ON(req->background);
490         spin_lock(&fc->lock);
491         if (!fc->connected)
492                 req->out.h.error = -ENOTCONN;
493         else if (fc->conn_error)
494                 req->out.h.error = -ECONNREFUSED;
495         else {
496                 req->in.h.unique = fuse_get_unique(fc);
497                 queue_request(fc, req);
498                 /* acquire extra reference, since request is still needed
499                    after request_end() */
500                 __fuse_get_request(req);
501 
502                 request_wait_answer(fc, req);
503         }
504         spin_unlock(&fc->lock);
505 }
506 
507 void fuse_request_send(struct fuse_conn *fc, struct fuse_req *req)
508 {
509         req->isreply = 1;
510         __fuse_request_send(fc, req);
511 }
512 EXPORT_SYMBOL_GPL(fuse_request_send);
513 
514 static void fuse_request_send_nowait_locked(struct fuse_conn *fc,
515                                             struct fuse_req *req)
516 {
517         BUG_ON(!req->background);
518         fc->num_background++;
519         if (fc->num_background == fc->max_background)
520                 fc->blocked = 1;
521         if (fc->num_background == fc->congestion_threshold &&
522             fc->bdi_initialized) {
523                 set_bdi_congested(&fc->bdi, BLK_RW_SYNC);
524                 set_bdi_congested(&fc->bdi, BLK_RW_ASYNC);
525         }
526         list_add_tail(&req->list, &fc->bg_queue);
527         flush_bg_queue(fc);
528 }
529 
530 static void fuse_request_send_nowait(struct fuse_conn *fc, struct fuse_req *req)
531 {
532         spin_lock(&fc->lock);
533         if (fc->connected) {
534                 fuse_request_send_nowait_locked(fc, req);
535                 spin_unlock(&fc->lock);
536         } else {
537                 req->out.h.error = -ENOTCONN;
538                 request_end(fc, req);
539         }
540 }
541 
542 void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req)
543 {
544         req->isreply = 1;
545         fuse_request_send_nowait(fc, req);
546 }
547 EXPORT_SYMBOL_GPL(fuse_request_send_background);
548 
549 static int fuse_request_send_notify_reply(struct fuse_conn *fc,
550                                           struct fuse_req *req, u64 unique)
551 {
552         int err = -ENODEV;
553 
554         req->isreply = 0;
555         req->in.h.unique = unique;
556         spin_lock(&fc->lock);
557         if (fc->connected) {
558                 queue_request(fc, req);
559                 err = 0;
560         }
561         spin_unlock(&fc->lock);
562 
563         return err;
564 }
565 
566 /*
567  * Called under fc->lock
568  *
569  * fc->connected must have been checked previously
570  */
571 void fuse_request_send_background_locked(struct fuse_conn *fc,
572                                          struct fuse_req *req)
573 {
574         req->isreply = 1;
575         fuse_request_send_nowait_locked(fc, req);
576 }
577 
578 void fuse_force_forget(struct file *file, u64 nodeid)
579 {
580         struct inode *inode = file_inode(file);
581         struct fuse_conn *fc = get_fuse_conn(inode);
582         struct fuse_req *req;
583         struct fuse_forget_in inarg;
584 
585         memset(&inarg, 0, sizeof(inarg));
586         inarg.nlookup = 1;
587         req = fuse_get_req_nofail_nopages(fc, file);
588         req->in.h.opcode = FUSE_FORGET;
589         req->in.h.nodeid = nodeid;
590         req->in.numargs = 1;
591         req->in.args[0].size = sizeof(inarg);
592         req->in.args[0].value = &inarg;
593         req->isreply = 0;
594         __fuse_request_send(fc, req);
595         /* ignore errors */
596         fuse_put_request(fc, req);
597 }
598 
599 /*
600  * Lock the request.  Up to the next unlock_request() there mustn't be
601  * anything that could cause a page-fault.  If the request was already
602  * aborted bail out.
603  */
604 static int lock_request(struct fuse_conn *fc, struct fuse_req *req)
605 {
606         int err = 0;
607         if (req) {
608                 spin_lock(&fc->lock);
609                 if (req->aborted)
610                         err = -ENOENT;
611                 else
612                         req->locked = 1;
613                 spin_unlock(&fc->lock);
614         }
615         return err;
616 }
617 
618 /*
619  * Unlock request.  If it was aborted during being locked, the
620  * requester thread is currently waiting for it to be unlocked, so
621  * wake it up.
622  */
623 static void unlock_request(struct fuse_conn *fc, struct fuse_req *req)
624 {
625         if (req) {
626                 spin_lock(&fc->lock);
627                 req->locked = 0;
628                 if (req->aborted)
629                         wake_up(&req->waitq);
630                 spin_unlock(&fc->lock);
631         }
632 }
633 
634 struct fuse_copy_state {
635         struct fuse_conn *fc;
636         int write;
637         struct fuse_req *req;
638         const struct iovec *iov;
639         struct pipe_buffer *pipebufs;
640         struct pipe_buffer *currbuf;
641         struct pipe_inode_info *pipe;
642         unsigned long nr_segs;
643         unsigned long seglen;
644         unsigned long addr;
645         struct page *pg;
646         void *mapaddr;
647         void *buf;
648         unsigned len;
649         unsigned move_pages:1;
650 };
651 
652 static void fuse_copy_init(struct fuse_copy_state *cs, struct fuse_conn *fc,
653                            int write,
654                            const struct iovec *iov, unsigned long nr_segs)
655 {
656         memset(cs, 0, sizeof(*cs));
657         cs->fc = fc;
658         cs->write = write;
659         cs->iov = iov;
660         cs->nr_segs = nr_segs;
661 }
662 
663 /* Unmap and put previous page of userspace buffer */
664 static void fuse_copy_finish(struct fuse_copy_state *cs)
665 {
666         if (cs->currbuf) {
667                 struct pipe_buffer *buf = cs->currbuf;
668 
669                 if (!cs->write) {
670                         buf->ops->unmap(cs->pipe, buf, cs->mapaddr);
671                 } else {
672                         kunmap(buf->page);
673                         buf->len = PAGE_SIZE - cs->len;
674                 }
675                 cs->currbuf = NULL;
676                 cs->mapaddr = NULL;
677         } else if (cs->mapaddr) {
678                 kunmap(cs->pg);
679                 if (cs->write) {
680                         flush_dcache_page(cs->pg);
681                         set_page_dirty_lock(cs->pg);
682                 }
683                 put_page(cs->pg);
684                 cs->mapaddr = NULL;
685         }
686 }
687 
688 /*
689  * Get another pagefull of userspace buffer, and map it to kernel
690  * address space, and lock request
691  */
692 static int fuse_copy_fill(struct fuse_copy_state *cs)
693 {
694         unsigned long offset;
695         int err;
696 
697         unlock_request(cs->fc, cs->req);
698         fuse_copy_finish(cs);
699         if (cs->pipebufs) {
700                 struct pipe_buffer *buf = cs->pipebufs;
701 
702                 if (!cs->write) {
703                         err = buf->ops->confirm(cs->pipe, buf);
704                         if (err)
705                                 return err;
706 
707                         BUG_ON(!cs->nr_segs);
708                         cs->currbuf = buf;
709                         cs->mapaddr = buf->ops->map(cs->pipe, buf, 0);
710                         cs->len = buf->len;
711                         cs->buf = cs->mapaddr + buf->offset;
712                         cs->pipebufs++;
713                         cs->nr_segs--;
714                 } else {
715                         struct page *page;
716 
717                         if (cs->nr_segs == cs->pipe->buffers)
718                                 return -EIO;
719 
720                         page = alloc_page(GFP_HIGHUSER);
721                         if (!page)
722                                 return -ENOMEM;
723 
724                         buf->page = page;
725                         buf->offset = 0;
726                         buf->len = 0;
727 
728                         cs->currbuf = buf;
729                         cs->mapaddr = kmap(page);
730                         cs->buf = cs->mapaddr;
731                         cs->len = PAGE_SIZE;
732                         cs->pipebufs++;
733                         cs->nr_segs++;
734                 }
735         } else {
736                 if (!cs->seglen) {
737                         BUG_ON(!cs->nr_segs);
738                         cs->seglen = cs->iov[0].iov_len;
739                         cs->addr = (unsigned long) cs->iov[0].iov_base;
740                         cs->iov++;
741                         cs->nr_segs--;
742                 }
743                 err = get_user_pages_fast(cs->addr, 1, cs->write, &cs->pg);
744                 if (err < 0)
745                         return err;
746                 BUG_ON(err != 1);
747                 offset = cs->addr % PAGE_SIZE;
748                 cs->mapaddr = kmap(cs->pg);
749                 cs->buf = cs->mapaddr + offset;
750                 cs->len = min(PAGE_SIZE - offset, cs->seglen);
751                 cs->seglen -= cs->len;
752                 cs->addr += cs->len;
753         }
754 
755         return lock_request(cs->fc, cs->req);
756 }
757 
758 /* Do as much copy to/from userspace buffer as we can */
759 static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
760 {
761         unsigned ncpy = min(*size, cs->len);
762         if (val) {
763                 if (cs->write)
764                         memcpy(cs->buf, *val, ncpy);
765                 else
766                         memcpy(*val, cs->buf, ncpy);
767                 *val += ncpy;
768         }
769         *size -= ncpy;
770         cs->len -= ncpy;
771         cs->buf += ncpy;
772         return ncpy;
773 }
774 
775 static int fuse_check_page(struct page *page)
776 {
777         if (page_mapcount(page) ||
778             page->mapping != NULL ||
779             page_count(page) != 1 ||
780             (page->flags & PAGE_FLAGS_CHECK_AT_PREP &
781              ~(1 << PG_locked |
782                1 << PG_referenced |
783                1 << PG_uptodate |
784                1 << PG_lru |
785                1 << PG_active |
786                1 << PG_reclaim))) {
787                 printk(KERN_WARNING "fuse: trying to steal weird page\n");
788                 printk(KERN_WARNING "  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);
789                 return 1;
790         }
791         return 0;
792 }
793 
794 static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
795 {
796         int err;
797         struct page *oldpage = *pagep;
798         struct page *newpage;
799         struct pipe_buffer *buf = cs->pipebufs;
800 
801         unlock_request(cs->fc, cs->req);
802         fuse_copy_finish(cs);
803 
804         err = buf->ops->confirm(cs->pipe, buf);
805         if (err)
806                 return err;
807 
808         BUG_ON(!cs->nr_segs);
809         cs->currbuf = buf;
810         cs->len = buf->len;
811         cs->pipebufs++;
812         cs->nr_segs--;
813 
814         if (cs->len != PAGE_SIZE)
815                 goto out_fallback;
816 
817         if (buf->ops->steal(cs->pipe, buf) != 0)
818                 goto out_fallback;
819 
820         newpage = buf->page;
821 
822         if (WARN_ON(!PageUptodate(newpage)))
823                 return -EIO;
824 
825         ClearPageMappedToDisk(newpage);
826 
827         if (fuse_check_page(newpage) != 0)
828                 goto out_fallback_unlock;
829 
830         /*
831          * This is a new and locked page, it shouldn't be mapped or
832          * have any special flags on it
833          */
834         if (WARN_ON(page_mapped(oldpage)))
835                 goto out_fallback_unlock;
836         if (WARN_ON(page_has_private(oldpage)))
837                 goto out_fallback_unlock;
838         if (WARN_ON(PageDirty(oldpage) || PageWriteback(oldpage)))
839                 goto out_fallback_unlock;
840         if (WARN_ON(PageMlocked(oldpage)))
841                 goto out_fallback_unlock;
842 
843         err = replace_page_cache_page(oldpage, newpage, GFP_KERNEL);
844         if (err) {
845                 unlock_page(newpage);
846                 return err;
847         }
848 
849         page_cache_get(newpage);
850 
851         if (!(buf->flags & PIPE_BUF_FLAG_LRU))
852                 lru_cache_add_file(newpage);
853 
854         err = 0;
855         spin_lock(&cs->fc->lock);
856         if (cs->req->aborted)
857                 err = -ENOENT;
858         else
859                 *pagep = newpage;
860         spin_unlock(&cs->fc->lock);
861 
862         if (err) {
863                 unlock_page(newpage);
864                 page_cache_release(newpage);
865                 return err;
866         }
867 
868         unlock_page(oldpage);
869         page_cache_release(oldpage);
870         cs->len = 0;
871 
872         return 0;
873 
874 out_fallback_unlock:
875         unlock_page(newpage);
876 out_fallback:
877         cs->mapaddr = buf->ops->map(cs->pipe, buf, 1);
878         cs->buf = cs->mapaddr + buf->offset;
879 
880         err = lock_request(cs->fc, cs->req);
881         if (err)
882                 return err;
883 
884         return 1;
885 }
886 
887 static int fuse_ref_page(struct fuse_copy_state *cs, struct page *page,
888                          unsigned offset, unsigned count)
889 {
890         struct pipe_buffer *buf;
891 
892         if (cs->nr_segs == cs->pipe->buffers)
893                 return -EIO;
894 
895         unlock_request(cs->fc, cs->req);
896         fuse_copy_finish(cs);
897 
898         buf = cs->pipebufs;
899         page_cache_get(page);
900         buf->page = page;
901         buf->offset = offset;
902         buf->len = count;
903 
904         cs->pipebufs++;
905         cs->nr_segs++;
906         cs->len = 0;
907 
908         return 0;
909 }
910 
911 /*
912  * Copy a page in the request to/from the userspace buffer.  Must be
913  * done atomically
914  */
915 static int fuse_copy_page(struct fuse_copy_state *cs, struct page **pagep,
916                           unsigned offset, unsigned count, int zeroing)
917 {
918         int err;
919         struct page *page = *pagep;
920 
921         if (page && zeroing && count < PAGE_SIZE)
922                 clear_highpage(page);
923 
924         while (count) {
925                 if (cs->write && cs->pipebufs && page) {
926                         return fuse_ref_page(cs, page, offset, count);
927                 } else if (!cs->len) {
928                         if (cs->move_pages && page &&
929                             offset == 0 && count == PAGE_SIZE) {
930                                 err = fuse_try_move_page(cs, pagep);
931                                 if (err <= 0)
932                                         return err;
933                         } else {
934                                 err = fuse_copy_fill(cs);
935                                 if (err)
936                                         return err;
937                         }
938                 }
939                 if (page) {
940                         void *mapaddr = kmap_atomic(page);
941                         void *buf = mapaddr + offset;
942                         offset += fuse_copy_do(cs, &buf, &count);
943                         kunmap_atomic(mapaddr);
944                 } else
945                         offset += fuse_copy_do(cs, NULL, &count);
946         }
947         if (page && !cs->write)
948                 flush_dcache_page(page);
949         return 0;
950 }
951 
952 /* Copy pages in the request to/from userspace buffer */
953 static int fuse_copy_pages(struct fuse_copy_state *cs, unsigned nbytes,
954                            int zeroing)
955 {
956         unsigned i;
957         struct fuse_req *req = cs->req;
958 
959         for (i = 0; i < req->num_pages && (nbytes || zeroing); i++) {
960                 int err;
961                 unsigned offset = req->page_descs[i].offset;
962                 unsigned count = min(nbytes, req->page_descs[i].length);
963 
964                 err = fuse_copy_page(cs, &req->pages[i], offset, count,
965                                      zeroing);
966                 if (err)
967                         return err;
968 
969                 nbytes -= count;
970         }
971         return 0;
972 }
973 
974 /* Copy a single argument in the request to/from userspace buffer */
975 static int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned size)
976 {
977         while (size) {
978                 if (!cs->len) {
979                         int err = fuse_copy_fill(cs);
980                         if (err)
981                                 return err;
982                 }
983                 fuse_copy_do(cs, &val, &size);
984         }
985         return 0;
986 }
987 
988 /* Copy request arguments to/from userspace buffer */
989 static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs,
990                           unsigned argpages, struct fuse_arg *args,
991                           int zeroing)
992 {
993         int err = 0;
994         unsigned i;
995 
996         for (i = 0; !err && i < numargs; i++)  {
997                 struct fuse_arg *arg = &args[i];
998                 if (i == numargs - 1 && argpages)
999                         err = fuse_copy_pages(cs, arg->size, zeroing);
1000                 else
1001                         err = fuse_copy_one(cs, arg->value, arg->size);
1002         }
1003         return err;
1004 }
1005 
1006 static int forget_pending(struct fuse_conn *fc)
1007 {
1008         return fc->forget_list_head.next != NULL;
1009 }
1010 
1011 static int request_pending(struct fuse_conn *fc)
1012 {
1013         return !list_empty(&fc->pending) || !list_empty(&fc->interrupts) ||
1014                 forget_pending(fc);
1015 }
1016 
1017 /* Wait until a request is available on the pending list */
1018 static void request_wait(struct fuse_conn *fc)
1019 __releases(fc->lock)
1020 __acquires(fc->lock)
1021 {
1022         DECLARE_WAITQUEUE(wait, current);
1023 
1024         add_wait_queue_exclusive(&fc->waitq, &wait);
1025         while (fc->connected && !request_pending(fc)) {
1026                 set_current_state(TASK_INTERRUPTIBLE);
1027                 if (signal_pending(current))
1028                         break;
1029 
1030                 spin_unlock(&fc->lock);
1031                 schedule();
1032                 spin_lock(&fc->lock);
1033         }
1034         set_current_state(TASK_RUNNING);
1035         remove_wait_queue(&fc->waitq, &wait);
1036 }
1037 
1038 /*
1039  * Transfer an interrupt request to userspace
1040  *
1041  * Unlike other requests this is assembled on demand, without a need
1042  * to allocate a separate fuse_req structure.
1043  *
1044  * Called with fc->lock held, releases it
1045  */
1046 static int fuse_read_interrupt(struct fuse_conn *fc, struct fuse_copy_state *cs,
1047                                size_t nbytes, struct fuse_req *req)
1048 __releases(fc->lock)
1049 {
1050         struct fuse_in_header ih;
1051         struct fuse_interrupt_in arg;
1052         unsigned reqsize = sizeof(ih) + sizeof(arg);
1053         int err;
1054 
1055         list_del_init(&req->intr_entry);
1056         req->intr_unique = fuse_get_unique(fc);
1057         memset(&ih, 0, sizeof(ih));
1058         memset(&arg, 0, sizeof(arg));
1059         ih.len = reqsize;
1060         ih.opcode = FUSE_INTERRUPT;
1061         ih.unique = req->intr_unique;
1062         arg.unique = req->in.h.unique;
1063 
1064         spin_unlock(&fc->lock);
1065         if (nbytes < reqsize)
1066                 return -EINVAL;
1067 
1068         err = fuse_copy_one(cs, &ih, sizeof(ih));
1069         if (!err)
1070                 err = fuse_copy_one(cs, &arg, sizeof(arg));
1071         fuse_copy_finish(cs);
1072 
1073         return err ? err : reqsize;
1074 }
1075 
1076 static struct fuse_forget_link *dequeue_forget(struct fuse_conn *fc,
1077                                                unsigned max,
1078                                                unsigned *countp)
1079 {
1080         struct fuse_forget_link *head = fc->forget_list_head.next;
1081         struct fuse_forget_link **newhead = &head;
1082         unsigned count;
1083 
1084         for (count = 0; *newhead != NULL && count < max; count++)
1085                 newhead = &(*newhead)->next;
1086 
1087         fc->forget_list_head.next = *newhead;
1088         *newhead = NULL;
1089         if (fc->forget_list_head.next == NULL)
1090                 fc->forget_list_tail = &fc->forget_list_head;
1091 
1092         if (countp != NULL)
1093                 *countp = count;
1094 
1095         return head;
1096 }
1097 
1098 static int fuse_read_single_forget(struct fuse_conn *fc,
1099                                    struct fuse_copy_state *cs,
1100                                    size_t nbytes)
1101 __releases(fc->lock)
1102 {
1103         int err;
1104         struct fuse_forget_link *forget = dequeue_forget(fc, 1, NULL);
1105         struct fuse_forget_in arg = {
1106                 .nlookup = forget->forget_one.nlookup,
1107         };
1108         struct fuse_in_header ih = {
1109                 .opcode = FUSE_FORGET,
1110                 .nodeid = forget->forget_one.nodeid,
1111                 .unique = fuse_get_unique(fc),
1112                 .len = sizeof(ih) + sizeof(arg),
1113         };
1114 
1115         spin_unlock(&fc->lock);
1116         kfree(forget);
1117         if (nbytes < ih.len)
1118                 return -EINVAL;
1119 
1120         err = fuse_copy_one(cs, &ih, sizeof(ih));
1121         if (!err)
1122                 err = fuse_copy_one(cs, &arg, sizeof(arg));
1123         fuse_copy_finish(cs);
1124 
1125         if (err)
1126                 return err;
1127 
1128         return ih.len;
1129 }
1130 
1131 static int fuse_read_batch_forget(struct fuse_conn *fc,
1132                                    struct fuse_copy_state *cs, size_t nbytes)
1133 __releases(fc->lock)
1134 {
1135         int err;
1136         unsigned max_forgets;
1137         unsigned count;
1138         struct fuse_forget_link *head;
1139         struct fuse_batch_forget_in arg = { .count = 0 };
1140         struct fuse_in_header ih = {
1141                 .opcode = FUSE_BATCH_FORGET,
1142                 .unique = fuse_get_unique(fc),
1143                 .len = sizeof(ih) + sizeof(arg),
1144         };
1145 
1146         if (nbytes < ih.len) {
1147                 spin_unlock(&fc->lock);
1148                 return -EINVAL;
1149         }
1150 
1151         max_forgets = (nbytes - ih.len) / sizeof(struct fuse_forget_one);
1152         head = dequeue_forget(fc, max_forgets, &count);
1153         spin_unlock(&fc->lock);
1154 
1155         arg.count = count;
1156         ih.len += count * sizeof(struct fuse_forget_one);
1157         err = fuse_copy_one(cs, &ih, sizeof(ih));
1158         if (!err)
1159                 err = fuse_copy_one(cs, &arg, sizeof(arg));
1160 
1161         while (head) {
1162                 struct fuse_forget_link *forget = head;
1163 
1164                 if (!err) {
1165                         err = fuse_copy_one(cs, &forget->forget_one,
1166                                             sizeof(forget->forget_one));
1167                 }
1168                 head = forget->next;
1169                 kfree(forget);
1170         }
1171 
1172         fuse_copy_finish(cs);
1173 
1174         if (err)
1175                 return err;
1176 
1177         return ih.len;
1178 }
1179 
1180 static int fuse_read_forget(struct fuse_conn *fc, struct fuse_copy_state *cs,
1181                             size_t nbytes)
1182 __releases(fc->lock)
1183 {
1184         if (fc->minor < 16 || fc->forget_list_head.next->next == NULL)
1185                 return fuse_read_single_forget(fc, cs, nbytes);
1186         else
1187                 return fuse_read_batch_forget(fc, cs, nbytes);
1188 }
1189 
1190 /*
1191  * Read a single request into the userspace filesystem's buffer.  This
1192  * function waits until a request is available, then removes it from
1193  * the pending list and copies request data to userspace buffer.  If
1194  * no reply is needed (FORGET) or request has been aborted or there
1195  * was an error during the copying then it's finished by calling
1196  * request_end().  Otherwise add it to the processing list, and set
1197  * the 'sent' flag.
1198  */
1199 static ssize_t fuse_dev_do_read(struct fuse_conn *fc, struct file *file,
1200                                 struct fuse_copy_state *cs, size_t nbytes)
1201 {
1202         int err;
1203         struct fuse_req *req;
1204         struct fuse_in *in;
1205         unsigned reqsize;
1206 
1207  restart:
1208         spin_lock(&fc->lock);
1209         err = -EAGAIN;
1210         if ((file->f_flags & O_NONBLOCK) && fc->connected &&
1211             !request_pending(fc))
1212                 goto err_unlock;
1213 
1214         request_wait(fc);
1215         err = -ENODEV;
1216         if (!fc->connected)
1217                 goto err_unlock;
1218         err = -ERESTARTSYS;
1219         if (!request_pending(fc))
1220                 goto err_unlock;
1221 
1222         if (!list_empty(&fc->interrupts)) {
1223                 req = list_entry(fc->interrupts.next, struct fuse_req,
1224                                  intr_entry);
1225                 return fuse_read_interrupt(fc, cs, nbytes, req);
1226         }
1227 
1228         if (forget_pending(fc)) {
1229                 if (list_empty(&fc->pending) || fc->forget_batch-- > 0)
1230                         return fuse_read_forget(fc, cs, nbytes);
1231 
1232                 if (fc->forget_batch <= -8)
1233                         fc->forget_batch = 16;
1234         }
1235 
1236         req = list_entry(fc->pending.next, struct fuse_req, list);
1237         req->state = FUSE_REQ_READING;
1238         list_move(&req->list, &fc->io);
1239 
1240         in = &req->in;
1241         reqsize = in->h.len;
1242         /* If request is too large, reply with an error and restart the read */
1243         if (nbytes < reqsize) {
1244                 req->out.h.error = -EIO;
1245                 /* SETXATTR is special, since it may contain too large data */
1246                 if (in->h.opcode == FUSE_SETXATTR)
1247                         req->out.h.error = -E2BIG;
1248                 request_end(fc, req);
1249                 goto restart;
1250         }
1251         spin_unlock(&fc->lock);
1252         cs->req = req;
1253         err = fuse_copy_one(cs, &in->h, sizeof(in->h));
1254         if (!err)
1255                 err = fuse_copy_args(cs, in->numargs, in->argpages,
1256                                      (struct fuse_arg *) in->args, 0);
1257         fuse_copy_finish(cs);
1258         spin_lock(&fc->lock);
1259         req->locked = 0;
1260         if (req->aborted) {
1261                 request_end(fc, req);
1262                 return -ENODEV;
1263         }
1264         if (err) {
1265                 req->out.h.error = -EIO;
1266                 request_end(fc, req);
1267                 return err;
1268         }
1269         if (!req->isreply)
1270                 request_end(fc, req);
1271         else {
1272                 req->state = FUSE_REQ_SENT;
1273                 list_move_tail(&req->list, &fc->processing);
1274                 if (req->interrupted)
1275                         queue_interrupt(fc, req);
1276                 spin_unlock(&fc->lock);
1277         }
1278         return reqsize;
1279 
1280  err_unlock:
1281         spin_unlock(&fc->lock);
1282         return err;
1283 }
1284 
1285 static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
1286                               unsigned long nr_segs, loff_t pos)
1287 {
1288         struct fuse_copy_state cs;
1289         struct file *file = iocb->ki_filp;
1290         struct fuse_conn *fc = fuse_get_conn(file);
1291         if (!fc)
1292                 return -EPERM;
1293 
1294         fuse_copy_init(&cs, fc, 1, iov, nr_segs);
1295 
1296         return fuse_dev_do_read(fc, file, &cs, iov_length(iov, nr_segs));
1297 }
1298 
1299 static int fuse_dev_pipe_buf_steal(struct pipe_inode_info *pipe,
1300                                    struct pipe_buffer *buf)
1301 {
1302         return 1;
1303 }
1304 
1305 static const struct pipe_buf_operations fuse_dev_pipe_buf_ops = {
1306         .can_merge = 0,
1307         .map = generic_pipe_buf_map,
1308         .unmap = generic_pipe_buf_unmap,
1309         .confirm = generic_pipe_buf_confirm,
1310         .release = generic_pipe_buf_release,
1311         .steal = fuse_dev_pipe_buf_steal,
1312         .get = generic_pipe_buf_get,
1313 };
1314 
1315 static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
1316                                     struct pipe_inode_info *pipe,
1317                                     size_t len, unsigned int flags)
1318 {
1319         int ret;
1320         int page_nr = 0;
1321         int do_wakeup = 0;
1322         struct pipe_buffer *bufs;
1323         struct fuse_copy_state cs;
1324         struct fuse_conn *fc = fuse_get_conn(in);
1325         if (!fc)
1326                 return -EPERM;
1327 
1328         bufs = kmalloc(pipe->buffers * sizeof(struct pipe_buffer), GFP_KERNEL);
1329         if (!bufs)
1330                 return -ENOMEM;
1331 
1332         fuse_copy_init(&cs, fc, 1, NULL, 0);
1333         cs.pipebufs = bufs;
1334         cs.pipe = pipe;
1335         ret = fuse_dev_do_read(fc, in, &cs, len);
1336         if (ret < 0)
1337                 goto out;
1338 
1339         ret = 0;
1340         pipe_lock(pipe);
1341 
1342         if (!pipe->readers) {
1343                 send_sig(SIGPIPE, current, 0);
1344                 if (!ret)
1345                         ret = -EPIPE;
1346                 goto out_unlock;
1347         }
1348 
1349         if (pipe->nrbufs + cs.nr_segs > pipe->buffers) {
1350                 ret = -EIO;
1351                 goto out_unlock;
1352         }
1353 
1354         while (page_nr < cs.nr_segs) {
1355                 int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
1356                 struct pipe_buffer *buf = pipe->bufs + newbuf;
1357 
1358                 buf->page = bufs[page_nr].page;
1359                 buf->offset = bufs[page_nr].offset;
1360                 buf->len = bufs[page_nr].len;
1361                 buf->ops = &fuse_dev_pipe_buf_ops;
1362 
1363                 pipe->nrbufs++;
1364                 page_nr++;
1365                 ret += buf->len;
1366 
1367                 if (pipe->files)
1368                         do_wakeup = 1;
1369         }
1370 
1371 out_unlock:
1372         pipe_unlock(pipe);
1373 
1374         if (do_wakeup) {
1375                 smp_mb();
1376                 if (waitqueue_active(&pipe->wait))
1377                         wake_up_interruptible(&pipe->wait);
1378                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
1379         }
1380 
1381 out:
1382         for (; page_nr < cs.nr_segs; page_nr++)
1383                 page_cache_release(bufs[page_nr].page);
1384 
1385         kfree(bufs);
1386         return ret;
1387 }
1388 
1389 static int fuse_notify_poll(struct fuse_conn *fc, unsigned int size,
1390                             struct fuse_copy_state *cs)
1391 {
1392         struct fuse_notify_poll_wakeup_out outarg;
1393         int err = -EINVAL;
1394 
1395         if (size != sizeof(outarg))
1396                 goto err;
1397 
1398         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1399         if (err)
1400                 goto err;
1401 
1402         fuse_copy_finish(cs);
1403         return fuse_notify_poll_wakeup(fc, &outarg);
1404 
1405 err:
1406         fuse_copy_finish(cs);
1407         return err;
1408 }
1409 
1410 static int fuse_notify_inval_inode(struct fuse_conn *fc, unsigned int size,
1411                                    struct fuse_copy_state *cs)
1412 {
1413         struct fuse_notify_inval_inode_out outarg;
1414         int err = -EINVAL;
1415 
1416         if (size != sizeof(outarg))
1417                 goto err;
1418 
1419         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1420         if (err)
1421                 goto err;
1422         fuse_copy_finish(cs);
1423 
1424         down_read(&fc->killsb);
1425         err = -ENOENT;
1426         if (fc->sb) {
1427                 err = fuse_reverse_inval_inode(fc->sb, outarg.ino,
1428                                                outarg.off, outarg.len);
1429         }
1430         up_read(&fc->killsb);
1431         return err;
1432 
1433 err:
1434         fuse_copy_finish(cs);
1435         return err;
1436 }
1437 
1438 static int fuse_notify_inval_entry(struct fuse_conn *fc, unsigned int size,
1439                                    struct fuse_copy_state *cs)
1440 {
1441         struct fuse_notify_inval_entry_out outarg;
1442         int err = -ENOMEM;
1443         char *buf;
1444         struct qstr name;
1445 
1446         buf = kzalloc(FUSE_NAME_MAX + 1, GFP_KERNEL);
1447         if (!buf)
1448                 goto err;
1449 
1450         err = -EINVAL;
1451         if (size < sizeof(outarg))
1452                 goto err;
1453 
1454         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1455         if (err)
1456                 goto err;
1457 
1458         err = -ENAMETOOLONG;
1459         if (outarg.namelen > FUSE_NAME_MAX)
1460                 goto err;
1461 
1462         err = -EINVAL;
1463         if (size != sizeof(outarg) + outarg.namelen + 1)
1464                 goto err;
1465 
1466         name.name = buf;
1467         name.len = outarg.namelen;
1468         err = fuse_copy_one(cs, buf, outarg.namelen + 1);
1469         if (err)
1470                 goto err;
1471         fuse_copy_finish(cs);
1472         buf[outarg.namelen] = 0;
1473         name.hash = full_name_hash(name.name, name.len);
1474 
1475         down_read(&fc->killsb);
1476         err = -ENOENT;
1477         if (fc->sb)
1478                 err = fuse_reverse_inval_entry(fc->sb, outarg.parent, 0, &name);
1479         up_read(&fc->killsb);
1480         kfree(buf);
1481         return err;
1482 
1483 err:
1484         kfree(buf);
1485         fuse_copy_finish(cs);
1486         return err;
1487 }
1488 
1489 static int fuse_notify_delete(struct fuse_conn *fc, unsigned int size,
1490                               struct fuse_copy_state *cs)
1491 {
1492         struct fuse_notify_delete_out outarg;
1493         int err = -ENOMEM;
1494         char *buf;
1495         struct qstr name;
1496 
1497         buf = kzalloc(FUSE_NAME_MAX + 1, GFP_KERNEL);
1498         if (!buf)
1499                 goto err;
1500 
1501         err = -EINVAL;
1502         if (size < sizeof(outarg))
1503                 goto err;
1504 
1505         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1506         if (err)
1507                 goto err;
1508 
1509         err = -ENAMETOOLONG;
1510         if (outarg.namelen > FUSE_NAME_MAX)
1511                 goto err;
1512 
1513         err = -EINVAL;
1514         if (size != sizeof(outarg) + outarg.namelen + 1)
1515                 goto err;
1516 
1517         name.name = buf;
1518         name.len = outarg.namelen;
1519         err = fuse_copy_one(cs, buf, outarg.namelen + 1);
1520         if (err)
1521                 goto err;
1522         fuse_copy_finish(cs);
1523         buf[outarg.namelen] = 0;
1524         name.hash = full_name_hash(name.name, name.len);
1525 
1526         down_read(&fc->killsb);
1527         err = -ENOENT;
1528         if (fc->sb)
1529                 err = fuse_reverse_inval_entry(fc->sb, outarg.parent,
1530                                                outarg.child, &name);
1531         up_read(&fc->killsb);
1532         kfree(buf);
1533         return err;
1534 
1535 err:
1536         kfree(buf);
1537         fuse_copy_finish(cs);
1538         return err;
1539 }
1540 
1541 static int fuse_notify_store(struct fuse_conn *fc, unsigned int size,
1542                              struct fuse_copy_state *cs)
1543 {
1544         struct fuse_notify_store_out outarg;
1545         struct inode *inode;
1546         struct address_space *mapping;
1547         u64 nodeid;
1548         int err;
1549         pgoff_t index;
1550         unsigned int offset;
1551         unsigned int num;
1552         loff_t file_size;
1553         loff_t end;
1554 
1555         err = -EINVAL;
1556         if (size < sizeof(outarg))
1557                 goto out_finish;
1558 
1559         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1560         if (err)
1561                 goto out_finish;
1562 
1563         err = -EINVAL;
1564         if (size - sizeof(outarg) != outarg.size)
1565                 goto out_finish;
1566 
1567         nodeid = outarg.nodeid;
1568 
1569         down_read(&fc->killsb);
1570 
1571         err = -ENOENT;
1572         if (!fc->sb)
1573                 goto out_up_killsb;
1574 
1575         inode = ilookup5(fc->sb, nodeid, fuse_inode_eq, &nodeid);
1576         if (!inode)
1577                 goto out_up_killsb;
1578 
1579         mapping = inode->i_mapping;
1580         index = outarg.offset >> PAGE_CACHE_SHIFT;
1581         offset = outarg.offset & ~PAGE_CACHE_MASK;
1582         file_size = i_size_read(inode);
1583         end = outarg.offset + outarg.size;
1584         if (end > file_size) {
1585                 file_size = end;
1586                 fuse_write_update_size(inode, file_size);
1587         }
1588 
1589         num = outarg.size;
1590         while (num) {
1591                 struct page *page;
1592                 unsigned int this_num;
1593 
1594                 err = -ENOMEM;
1595                 page = find_or_create_page(mapping, index,
1596                                            mapping_gfp_mask(mapping));
1597                 if (!page)
1598                         goto out_iput;
1599 
1600                 this_num = min_t(unsigned, num, PAGE_CACHE_SIZE - offset);
1601                 err = fuse_copy_page(cs, &page, offset, this_num, 0);
1602                 if (!err && offset == 0 && (num != 0 || file_size == end))
1603                         SetPageUptodate(page);
1604                 unlock_page(page);
1605                 page_cache_release(page);
1606 
1607                 if (err)
1608                         goto out_iput;
1609 
1610                 num -= this_num;
1611                 offset = 0;
1612                 index++;
1613         }
1614 
1615         err = 0;
1616 
1617 out_iput:
1618         iput(inode);
1619 out_up_killsb:
1620         up_read(&fc->killsb);
1621 out_finish:
1622         fuse_copy_finish(cs);
1623         return err;
1624 }
1625 
1626 static void fuse_retrieve_end(struct fuse_conn *fc, struct fuse_req *req)
1627 {
1628         release_pages(req->pages, req->num_pages, 0);
1629 }
1630 
1631 static int fuse_retrieve(struct fuse_conn *fc, struct inode *inode,
1632                          struct fuse_notify_retrieve_out *outarg)
1633 {
1634         int err;
1635         struct address_space *mapping = inode->i_mapping;
1636         struct fuse_req *req;
1637         pgoff_t index;
1638         loff_t file_size;
1639         unsigned int num;
1640         unsigned int offset;
1641         size_t total_len = 0;
1642         int num_pages;
1643 
1644         offset = outarg->offset & ~PAGE_CACHE_MASK;
1645         file_size = i_size_read(inode);
1646 
1647         num = outarg->size;
1648         if (outarg->offset > file_size)
1649                 num = 0;
1650         else if (outarg->offset + num > file_size)
1651                 num = file_size - outarg->offset;
1652 
1653         num_pages = (num + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
1654         num_pages = min(num_pages, FUSE_MAX_PAGES_PER_REQ);
1655 
1656         req = fuse_get_req(fc, num_pages);
1657         if (IS_ERR(req))
1658                 return PTR_ERR(req);
1659 
1660         req->in.h.opcode = FUSE_NOTIFY_REPLY;
1661         req->in.h.nodeid = outarg->nodeid;
1662         req->in.numargs = 2;
1663         req->in.argpages = 1;
1664         req->page_descs[0].offset = offset;
1665         req->end = fuse_retrieve_end;
1666 
1667         index = outarg->offset >> PAGE_CACHE_SHIFT;
1668 
1669         while (num && req->num_pages < num_pages) {
1670                 struct page *page;
1671                 unsigned int this_num;
1672 
1673                 page = find_get_page(mapping, index);
1674                 if (!page)
1675                         break;
1676 
1677                 this_num = min_t(unsigned, num, PAGE_CACHE_SIZE - offset);
1678                 req->pages[req->num_pages] = page;
1679                 req->page_descs[req->num_pages].length = this_num;
1680                 req->num_pages++;
1681 
1682                 offset = 0;
1683                 num -= this_num;
1684                 total_len += this_num;
1685                 index++;
1686         }
1687         req->misc.retrieve_in.offset = outarg->offset;
1688         req->misc.retrieve_in.size = total_len;
1689         req->in.args[0].size = sizeof(req->misc.retrieve_in);
1690         req->in.args[0].value = &req->misc.retrieve_in;
1691         req->in.args[1].size = total_len;
1692 
1693         err = fuse_request_send_notify_reply(fc, req, outarg->notify_unique);
1694         if (err)
1695                 fuse_retrieve_end(fc, req);
1696 
1697         return err;
1698 }
1699 
1700 static int fuse_notify_retrieve(struct fuse_conn *fc, unsigned int size,
1701                                 struct fuse_copy_state *cs)
1702 {
1703         struct fuse_notify_retrieve_out outarg;
1704         struct inode *inode;
1705         int err;
1706 
1707         err = -EINVAL;
1708         if (size != sizeof(outarg))
1709                 goto copy_finish;
1710 
1711         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1712         if (err)
1713                 goto copy_finish;
1714 
1715         fuse_copy_finish(cs);
1716 
1717         down_read(&fc->killsb);
1718         err = -ENOENT;
1719         if (fc->sb) {
1720                 u64 nodeid = outarg.nodeid;
1721 
1722                 inode = ilookup5(fc->sb, nodeid, fuse_inode_eq, &nodeid);
1723                 if (inode) {
1724                         err = fuse_retrieve(fc, inode, &outarg);
1725                         iput(inode);
1726                 }
1727         }
1728         up_read(&fc->killsb);
1729 
1730         return err;
1731 
1732 copy_finish:
1733         fuse_copy_finish(cs);
1734         return err;
1735 }
1736 
1737 static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
1738                        unsigned int size, struct fuse_copy_state *cs)
1739 {
1740         switch (code) {
1741         case FUSE_NOTIFY_POLL:
1742                 return fuse_notify_poll(fc, size, cs);
1743 
1744         case FUSE_NOTIFY_INVAL_INODE:
1745                 return fuse_notify_inval_inode(fc, size, cs);
1746 
1747         case FUSE_NOTIFY_INVAL_ENTRY:
1748                 return fuse_notify_inval_entry(fc, size, cs);
1749 
1750         case FUSE_NOTIFY_STORE:
1751                 return fuse_notify_store(fc, size, cs);
1752 
1753         case FUSE_NOTIFY_RETRIEVE:
1754                 return fuse_notify_retrieve(fc, size, cs);
1755 
1756         case FUSE_NOTIFY_DELETE:
1757                 return fuse_notify_delete(fc, size, cs);
1758 
1759         default:
1760                 fuse_copy_finish(cs);
1761                 return -EINVAL;
1762         }
1763 }
1764 
1765 /* Look up request on processing list by unique ID */
1766 static struct fuse_req *request_find(struct fuse_conn *fc, u64 unique)
1767 {
1768         struct list_head *entry;
1769 
1770         list_for_each(entry, &fc->processing) {
1771                 struct fuse_req *req;
1772                 req = list_entry(entry, struct fuse_req, list);
1773                 if (req->in.h.unique == unique || req->intr_unique == unique)
1774                         return req;
1775         }
1776         return NULL;
1777 }
1778 
1779 static int copy_out_args(struct fuse_copy_state *cs, struct fuse_out *out,
1780                          unsigned nbytes)
1781 {
1782         unsigned reqsize = sizeof(struct fuse_out_header);
1783 
1784         if (out->h.error)
1785                 return nbytes != reqsize ? -EINVAL : 0;
1786 
1787         reqsize += len_args(out->numargs, out->args);
1788 
1789         if (reqsize < nbytes || (reqsize > nbytes && !out->argvar))
1790                 return -EINVAL;
1791         else if (reqsize > nbytes) {
1792                 struct fuse_arg *lastarg = &out->args[out->numargs-1];
1793                 unsigned diffsize = reqsize - nbytes;
1794                 if (diffsize > lastarg->size)
1795                         return -EINVAL;
1796                 lastarg->size -= diffsize;
1797         }
1798         return fuse_copy_args(cs, out->numargs, out->argpages, out->args,
1799                               out->page_zeroing);
1800 }
1801 
1802 /*
1803  * Write a single reply to a request.  First the header is copied from
1804  * the write buffer.  The request is then searched on the processing
1805  * list by the unique ID found in the header.  If found, then remove
1806  * it from the list and copy the rest of the buffer to the request.
1807  * The request is finished by calling request_end()
1808  */
1809 static ssize_t fuse_dev_do_write(struct fuse_conn *fc,
1810                                  struct fuse_copy_state *cs, size_t nbytes)
1811 {
1812         int err;
1813         struct fuse_req *req;
1814         struct fuse_out_header oh;
1815 
1816         if (nbytes < sizeof(struct fuse_out_header))
1817                 return -EINVAL;
1818 
1819         err = fuse_copy_one(cs, &oh, sizeof(oh));
1820         if (err)
1821                 goto err_finish;
1822 
1823         err = -EINVAL;
1824         if (oh.len != nbytes)
1825                 goto err_finish;
1826 
1827         /*
1828          * Zero oh.unique indicates unsolicited notification message
1829          * and error contains notification code.
1830          */
1831         if (!oh.unique) {
1832                 err = fuse_notify(fc, oh.error, nbytes - sizeof(oh), cs);
1833                 return err ? err : nbytes;
1834         }
1835 
1836         err = -EINVAL;
1837         if (oh.error <= -1000 || oh.error > 0)
1838                 goto err_finish;
1839 
1840         spin_lock(&fc->lock);
1841         err = -ENOENT;
1842         if (!fc->connected)
1843                 goto err_unlock;
1844 
1845         req = request_find(fc, oh.unique);
1846         if (!req)
1847                 goto err_unlock;
1848 
1849         if (req->aborted) {
1850                 spin_unlock(&fc->lock);
1851                 fuse_copy_finish(cs);
1852                 spin_lock(&fc->lock);
1853                 request_end(fc, req);
1854                 return -ENOENT;
1855         }
1856         /* Is it an interrupt reply? */
1857         if (req->intr_unique == oh.unique) {
1858                 err = -EINVAL;
1859                 if (nbytes != sizeof(struct fuse_out_header))
1860                         goto err_unlock;
1861 
1862                 if (oh.error == -ENOSYS)
1863                         fc->no_interrupt = 1;
1864                 else if (oh.error == -EAGAIN)
1865                         queue_interrupt(fc, req);
1866 
1867                 spin_unlock(&fc->lock);
1868                 fuse_copy_finish(cs);
1869                 return nbytes;
1870         }
1871 
1872         req->state = FUSE_REQ_WRITING;
1873         list_move(&req->list, &fc->io);
1874         req->out.h = oh;
1875         req->locked = 1;
1876         cs->req = req;
1877         if (!req->out.page_replace)
1878                 cs->move_pages = 0;
1879         spin_unlock(&fc->lock);
1880 
1881         err = copy_out_args(cs, &req->out, nbytes);
1882         fuse_copy_finish(cs);
1883 
1884         spin_lock(&fc->lock);
1885         req->locked = 0;
1886         if (!err) {
1887                 if (req->aborted)
1888                         err = -ENOENT;
1889         } else if (!req->aborted)
1890                 req->out.h.error = -EIO;
1891         request_end(fc, req);
1892 
1893         return err ? err : nbytes;
1894 
1895  err_unlock:
1896         spin_unlock(&fc->lock);
1897  err_finish:
1898         fuse_copy_finish(cs);
1899         return err;
1900 }
1901 
1902 static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov,
1903                               unsigned long nr_segs, loff_t pos)
1904 {
1905         struct fuse_copy_state cs;
1906         struct fuse_conn *fc = fuse_get_conn(iocb->ki_filp);
1907         if (!fc)
1908                 return -EPERM;
1909 
1910         fuse_copy_init(&cs, fc, 0, iov, nr_segs);
1911 
1912         return fuse_dev_do_write(fc, &cs, iov_length(iov, nr_segs));
1913 }
1914 
1915 static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
1916                                      struct file *out, loff_t *ppos,
1917                                      size_t len, unsigned int flags)
1918 {
1919         unsigned nbuf;
1920         unsigned idx;
1921         struct pipe_buffer *bufs;
1922         struct fuse_copy_state cs;
1923         struct fuse_conn *fc;
1924         size_t rem;
1925         ssize_t ret;
1926 
1927         fc = fuse_get_conn(out);
1928         if (!fc)
1929                 return -EPERM;
1930 
1931         bufs = kmalloc(pipe->buffers * sizeof(struct pipe_buffer), GFP_KERNEL);
1932         if (!bufs)
1933                 return -ENOMEM;
1934 
1935         pipe_lock(pipe);
1936         nbuf = 0;
1937         rem = 0;
1938         for (idx = 0; idx < pipe->nrbufs && rem < len; idx++)
1939                 rem += pipe->bufs[(pipe->curbuf + idx) & (pipe->buffers - 1)].len;
1940 
1941         ret = -EINVAL;
1942         if (rem < len) {
1943                 pipe_unlock(pipe);
1944                 goto out;
1945         }
1946 
1947         rem = len;
1948         while (rem) {
1949                 struct pipe_buffer *ibuf;
1950                 struct pipe_buffer *obuf;
1951 
1952                 BUG_ON(nbuf >= pipe->buffers);
1953                 BUG_ON(!pipe->nrbufs);
1954                 ibuf = &pipe->bufs[pipe->curbuf];
1955                 obuf = &bufs[nbuf];
1956 
1957                 if (rem >= ibuf->len) {
1958                         *obuf = *ibuf;
1959                         ibuf->ops = NULL;
1960                         pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
1961                         pipe->nrbufs--;
1962                 } else {
1963                         ibuf->ops->get(pipe, ibuf);
1964                         *obuf = *ibuf;
1965                         obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1966                         obuf->len = rem;
1967                         ibuf->offset += obuf->len;
1968                         ibuf->len -= obuf->len;
1969                 }
1970                 nbuf++;
1971                 rem -= obuf->len;
1972         }
1973         pipe_unlock(pipe);
1974 
1975         fuse_copy_init(&cs, fc, 0, NULL, nbuf);
1976         cs.pipebufs = bufs;
1977         cs.pipe = pipe;
1978 
1979         if (flags & SPLICE_F_MOVE)
1980                 cs.move_pages = 1;
1981 
1982         ret = fuse_dev_do_write(fc, &cs, len);
1983 
1984         for (idx = 0; idx < nbuf; idx++) {
1985                 struct pipe_buffer *buf = &bufs[idx];
1986                 buf->ops->release(pipe, buf);
1987         }
1988 out:
1989         kfree(bufs);
1990         return ret;
1991 }
1992 
1993 static unsigned fuse_dev_poll(struct file *file, poll_table *wait)
1994 {
1995         unsigned mask = POLLOUT | POLLWRNORM;
1996         struct fuse_conn *fc = fuse_get_conn(file);
1997         if (!fc)
1998                 return POLLERR;
1999 
2000         poll_wait(file, &fc->waitq, wait);
2001 
2002         spin_lock(&fc->lock);
2003         if (!fc->connected)
2004                 mask = POLLERR;
2005         else if (request_pending(fc))
2006                 mask |= POLLIN | POLLRDNORM;
2007         spin_unlock(&fc->lock);
2008 
2009         return mask;
2010 }
2011 
2012 /*
2013  * Abort all requests on the given list (pending or processing)
2014  *
2015  * This function releases and reacquires fc->lock
2016  */
2017 static void end_requests(struct fuse_conn *fc, struct list_head *head)
2018 __releases(fc->lock)
2019 __acquires(fc->lock)
2020 {
2021         while (!list_empty(head)) {
2022                 struct fuse_req *req;
2023                 req = list_entry(head->next, struct fuse_req, list);
2024                 req->out.h.error = -ECONNABORTED;
2025                 request_end(fc, req);
2026                 spin_lock(&fc->lock);
2027         }
2028 }
2029 
2030 /*
2031  * Abort requests under I/O
2032  *
2033  * The requests are set to aborted and finished, and the request
2034  * waiter is woken up.  This will make request_wait_answer() wait
2035  * until the request is unlocked and then return.
2036  *
2037  * If the request is asynchronous, then the end function needs to be
2038  * called after waiting for the request to be unlocked (if it was
2039  * locked).
2040  */
2041 static void end_io_requests(struct fuse_conn *fc)
2042 __releases(fc->lock)
2043 __acquires(fc->lock)
2044 {
2045         while (!list_empty(&fc->io)) {
2046                 struct fuse_req *req =
2047                         list_entry(fc->io.next, struct fuse_req, list);
2048                 void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
2049 
2050                 req->aborted = 1;
2051                 req->out.h.error = -ECONNABORTED;
2052                 req->state = FUSE_REQ_FINISHED;
2053                 list_del_init(&req->list);
2054                 wake_up(&req->waitq);
2055                 if (end) {
2056                         req->end = NULL;
2057                         __fuse_get_request(req);
2058                         spin_unlock(&fc->lock);
2059                         wait_event(req->waitq, !req->locked);
2060                         end(fc, req);
2061                         fuse_put_request(fc, req);
2062                         spin_lock(&fc->lock);
2063                 }
2064         }
2065 }
2066 
2067 static void end_queued_requests(struct fuse_conn *fc)
2068 __releases(fc->lock)
2069 __acquires(fc->lock)
2070 {
2071         fc->max_background = UINT_MAX;
2072         flush_bg_queue(fc);
2073         end_requests(fc, &fc->pending);
2074         end_requests(fc, &fc->processing);
2075         while (forget_pending(fc))
2076                 kfree(dequeue_forget(fc, 1, NULL));
2077 }
2078 
2079 static void end_polls(struct fuse_conn *fc)
2080 {
2081         struct rb_node *p;
2082 
2083         p = rb_first(&fc->polled_files);
2084 
2085         while (p) {
2086                 struct fuse_file *ff;
2087                 ff = rb_entry(p, struct fuse_file, polled_node);
2088                 wake_up_interruptible_all(&ff->poll_wait);
2089 
2090                 p = rb_next(p);
2091         }
2092 }
2093 
2094 /*
2095  * Abort all requests.
2096  *
2097  * Emergency exit in case of a malicious or accidental deadlock, or
2098  * just a hung filesystem.
2099  *
2100  * The same effect is usually achievable through killing the
2101  * filesystem daemon and all users of the filesystem.  The exception
2102  * is the combination of an asynchronous request and the tricky
2103  * deadlock (see Documentation/filesystems/fuse.txt).
2104  *
2105  * During the aborting, progression of requests from the pending and
2106  * processing lists onto the io list, and progression of new requests
2107  * onto the pending list is prevented by req->connected being false.
2108  *
2109  * Progression of requests under I/O to the processing list is
2110  * prevented by the req->aborted flag being true for these requests.
2111  * For this reason requests on the io list must be aborted first.
2112  */
2113 void fuse_abort_conn(struct fuse_conn *fc)
2114 {
2115         spin_lock(&fc->lock);
2116         if (fc->connected) {
2117                 fc->connected = 0;
2118                 fc->blocked = 0;
2119                 fc->initialized = 1;
2120                 end_io_requests(fc);
2121                 end_queued_requests(fc);
2122                 end_polls(fc);
2123                 wake_up_all(&fc->waitq);
2124                 wake_up_all(&fc->blocked_waitq);
2125                 kill_fasync(&fc->fasync, SIGIO, POLL_IN);
2126         }
2127         spin_unlock(&fc->lock);
2128 }
2129 EXPORT_SYMBOL_GPL(fuse_abort_conn);
2130 
2131 int fuse_dev_release(struct inode *inode, struct file *file)
2132 {
2133         struct fuse_conn *fc = fuse_get_conn(file);
2134         if (fc) {
2135                 spin_lock(&fc->lock);
2136                 fc->connected = 0;
2137                 fc->blocked = 0;
2138                 fc->initialized = 1;
2139                 end_queued_requests(fc);
2140                 end_polls(fc);
2141                 wake_up_all(&fc->blocked_waitq);
2142                 spin_unlock(&fc->lock);
2143                 fuse_conn_put(fc);
2144         }
2145 
2146         return 0;
2147 }
2148 EXPORT_SYMBOL_GPL(fuse_dev_release);
2149 
2150 static int fuse_dev_fasync(int fd, struct file *file, int on)
2151 {
2152         struct fuse_conn *fc = fuse_get_conn(file);
2153         if (!fc)
2154                 return -EPERM;
2155 
2156         /* No locking - fasync_helper does its own locking */
2157         return fasync_helper(fd, file, on, &fc->fasync);
2158 }
2159 
2160 const struct file_operations fuse_dev_operations = {
2161         .owner          = THIS_MODULE,
2162         .llseek         = no_llseek,
2163         .read           = do_sync_read,
2164         .aio_read       = fuse_dev_read,
2165         .splice_read    = fuse_dev_splice_read,
2166         .write          = do_sync_write,
2167         .aio_write      = fuse_dev_write,
2168         .splice_write   = fuse_dev_splice_write,
2169         .poll           = fuse_dev_poll,
2170         .release        = fuse_dev_release,
2171         .fasync         = fuse_dev_fasync,
2172 };
2173 EXPORT_SYMBOL_GPL(fuse_dev_operations);
2174 
2175 static struct miscdevice fuse_miscdevice = {
2176         .minor = FUSE_MINOR,
2177         .name  = "fuse",
2178         .fops = &fuse_dev_operations,
2179 };
2180 
2181 int __init fuse_dev_init(void)
2182 {
2183         int err = -ENOMEM;
2184         fuse_req_cachep = kmem_cache_create("fuse_request",
2185                                             sizeof(struct fuse_req),
2186                                             0, 0, NULL);
2187         if (!fuse_req_cachep)
2188                 goto out;
2189 
2190         err = misc_register(&fuse_miscdevice);
2191         if (err)
2192                 goto out_cache_clean;
2193 
2194         return 0;
2195 
2196  out_cache_clean:
2197         kmem_cache_destroy(fuse_req_cachep);
2198  out:
2199         return err;
2200 }
2201 
2202 void fuse_dev_cleanup(void)
2203 {
2204         misc_deregister(&fuse_miscdevice);
2205         kmem_cache_destroy(fuse_req_cachep);
2206 }
2207 

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