Merge tag 'for-6.4-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave...
[platform/kernel/linux-rpi.git] / fs / fuse / dev.c
1 /*
2   FUSE: Filesystem in Userspace
3   Copyright (C) 2001-2008  Miklos Szeredi <miklos@szeredi.hu>
4
5   This program can be distributed under the terms of the GNU GPL.
6   See the file COPYING.
7 */
8
9 #include "fuse_i.h"
10
11 #include <linux/init.h>
12 #include <linux/module.h>
13 #include <linux/poll.h>
14 #include <linux/sched/signal.h>
15 #include <linux/uio.h>
16 #include <linux/miscdevice.h>
17 #include <linux/pagemap.h>
18 #include <linux/file.h>
19 #include <linux/slab.h>
20 #include <linux/pipe_fs_i.h>
21 #include <linux/swap.h>
22 #include <linux/splice.h>
23 #include <linux/sched.h>
24
25 MODULE_ALIAS_MISCDEV(FUSE_MINOR);
26 MODULE_ALIAS("devname:fuse");
27
28 /* Ordinary requests have even IDs, while interrupts IDs are odd */
29 #define FUSE_INT_REQ_BIT (1ULL << 0)
30 #define FUSE_REQ_ID_STEP (1ULL << 1)
31
32 static struct kmem_cache *fuse_req_cachep;
33
34 static struct fuse_dev *fuse_get_dev(struct file *file)
35 {
36         /*
37          * Lockless access is OK, because file->private data is set
38          * once during mount and is valid until the file is released.
39          */
40         return READ_ONCE(file->private_data);
41 }
42
43 static void fuse_request_init(struct fuse_mount *fm, struct fuse_req *req)
44 {
45         INIT_LIST_HEAD(&req->list);
46         INIT_LIST_HEAD(&req->intr_entry);
47         init_waitqueue_head(&req->waitq);
48         refcount_set(&req->count, 1);
49         __set_bit(FR_PENDING, &req->flags);
50         req->fm = fm;
51 }
52
53 static struct fuse_req *fuse_request_alloc(struct fuse_mount *fm, gfp_t flags)
54 {
55         struct fuse_req *req = kmem_cache_zalloc(fuse_req_cachep, flags);
56         if (req)
57                 fuse_request_init(fm, req);
58
59         return req;
60 }
61
62 static void fuse_request_free(struct fuse_req *req)
63 {
64         kmem_cache_free(fuse_req_cachep, req);
65 }
66
67 static void __fuse_get_request(struct fuse_req *req)
68 {
69         refcount_inc(&req->count);
70 }
71
72 /* Must be called with > 1 refcount */
73 static void __fuse_put_request(struct fuse_req *req)
74 {
75         refcount_dec(&req->count);
76 }
77
78 void fuse_set_initialized(struct fuse_conn *fc)
79 {
80         /* Make sure stores before this are seen on another CPU */
81         smp_wmb();
82         fc->initialized = 1;
83 }
84
85 static bool fuse_block_alloc(struct fuse_conn *fc, bool for_background)
86 {
87         return !fc->initialized || (for_background && fc->blocked);
88 }
89
90 static void fuse_drop_waiting(struct fuse_conn *fc)
91 {
92         /*
93          * lockess check of fc->connected is okay, because atomic_dec_and_test()
94          * provides a memory barrier matched with the one in fuse_wait_aborted()
95          * to ensure no wake-up is missed.
96          */
97         if (atomic_dec_and_test(&fc->num_waiting) &&
98             !READ_ONCE(fc->connected)) {
99                 /* wake up aborters */
100                 wake_up_all(&fc->blocked_waitq);
101         }
102 }
103
104 static void fuse_put_request(struct fuse_req *req);
105
106 static struct fuse_req *fuse_get_req(struct fuse_mount *fm, bool for_background)
107 {
108         struct fuse_conn *fc = fm->fc;
109         struct fuse_req *req;
110         int err;
111         atomic_inc(&fc->num_waiting);
112
113         if (fuse_block_alloc(fc, for_background)) {
114                 err = -EINTR;
115                 if (wait_event_killable_exclusive(fc->blocked_waitq,
116                                 !fuse_block_alloc(fc, for_background)))
117                         goto out;
118         }
119         /* Matches smp_wmb() in fuse_set_initialized() */
120         smp_rmb();
121
122         err = -ENOTCONN;
123         if (!fc->connected)
124                 goto out;
125
126         err = -ECONNREFUSED;
127         if (fc->conn_error)
128                 goto out;
129
130         req = fuse_request_alloc(fm, GFP_KERNEL);
131         err = -ENOMEM;
132         if (!req) {
133                 if (for_background)
134                         wake_up(&fc->blocked_waitq);
135                 goto out;
136         }
137
138         req->in.h.uid = from_kuid(fc->user_ns, current_fsuid());
139         req->in.h.gid = from_kgid(fc->user_ns, current_fsgid());
140         req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns);
141
142         __set_bit(FR_WAITING, &req->flags);
143         if (for_background)
144                 __set_bit(FR_BACKGROUND, &req->flags);
145
146         if (unlikely(req->in.h.uid == ((uid_t)-1) ||
147                      req->in.h.gid == ((gid_t)-1))) {
148                 fuse_put_request(req);
149                 return ERR_PTR(-EOVERFLOW);
150         }
151         return req;
152
153  out:
154         fuse_drop_waiting(fc);
155         return ERR_PTR(err);
156 }
157
158 static void fuse_put_request(struct fuse_req *req)
159 {
160         struct fuse_conn *fc = req->fm->fc;
161
162         if (refcount_dec_and_test(&req->count)) {
163                 if (test_bit(FR_BACKGROUND, &req->flags)) {
164                         /*
165                          * We get here in the unlikely case that a background
166                          * request was allocated but not sent
167                          */
168                         spin_lock(&fc->bg_lock);
169                         if (!fc->blocked)
170                                 wake_up(&fc->blocked_waitq);
171                         spin_unlock(&fc->bg_lock);
172                 }
173
174                 if (test_bit(FR_WAITING, &req->flags)) {
175                         __clear_bit(FR_WAITING, &req->flags);
176                         fuse_drop_waiting(fc);
177                 }
178
179                 fuse_request_free(req);
180         }
181 }
182
183 unsigned int fuse_len_args(unsigned int numargs, struct fuse_arg *args)
184 {
185         unsigned nbytes = 0;
186         unsigned i;
187
188         for (i = 0; i < numargs; i++)
189                 nbytes += args[i].size;
190
191         return nbytes;
192 }
193 EXPORT_SYMBOL_GPL(fuse_len_args);
194
195 u64 fuse_get_unique(struct fuse_iqueue *fiq)
196 {
197         fiq->reqctr += FUSE_REQ_ID_STEP;
198         return fiq->reqctr;
199 }
200 EXPORT_SYMBOL_GPL(fuse_get_unique);
201
202 static unsigned int fuse_req_hash(u64 unique)
203 {
204         return hash_long(unique & ~FUSE_INT_REQ_BIT, FUSE_PQ_HASH_BITS);
205 }
206
207 /*
208  * A new request is available, wake fiq->waitq
209  */
210 static void fuse_dev_wake_and_unlock(struct fuse_iqueue *fiq)
211 __releases(fiq->lock)
212 {
213         wake_up(&fiq->waitq);
214         kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
215         spin_unlock(&fiq->lock);
216 }
217
218 const struct fuse_iqueue_ops fuse_dev_fiq_ops = {
219         .wake_forget_and_unlock         = fuse_dev_wake_and_unlock,
220         .wake_interrupt_and_unlock      = fuse_dev_wake_and_unlock,
221         .wake_pending_and_unlock        = fuse_dev_wake_and_unlock,
222 };
223 EXPORT_SYMBOL_GPL(fuse_dev_fiq_ops);
224
225 static void queue_request_and_unlock(struct fuse_iqueue *fiq,
226                                      struct fuse_req *req)
227 __releases(fiq->lock)
228 {
229         req->in.h.len = sizeof(struct fuse_in_header) +
230                 fuse_len_args(req->args->in_numargs,
231                               (struct fuse_arg *) req->args->in_args);
232         list_add_tail(&req->list, &fiq->pending);
233         fiq->ops->wake_pending_and_unlock(fiq);
234 }
235
236 void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
237                        u64 nodeid, u64 nlookup)
238 {
239         struct fuse_iqueue *fiq = &fc->iq;
240
241         forget->forget_one.nodeid = nodeid;
242         forget->forget_one.nlookup = nlookup;
243
244         spin_lock(&fiq->lock);
245         if (fiq->connected) {
246                 fiq->forget_list_tail->next = forget;
247                 fiq->forget_list_tail = forget;
248                 fiq->ops->wake_forget_and_unlock(fiq);
249         } else {
250                 kfree(forget);
251                 spin_unlock(&fiq->lock);
252         }
253 }
254
255 static void flush_bg_queue(struct fuse_conn *fc)
256 {
257         struct fuse_iqueue *fiq = &fc->iq;
258
259         while (fc->active_background < fc->max_background &&
260                !list_empty(&fc->bg_queue)) {
261                 struct fuse_req *req;
262
263                 req = list_first_entry(&fc->bg_queue, struct fuse_req, list);
264                 list_del(&req->list);
265                 fc->active_background++;
266                 spin_lock(&fiq->lock);
267                 req->in.h.unique = fuse_get_unique(fiq);
268                 queue_request_and_unlock(fiq, req);
269         }
270 }
271
272 /*
273  * This function is called when a request is finished.  Either a reply
274  * has arrived or it was aborted (and not yet sent) or some error
275  * occurred during communication with userspace, or the device file
276  * was closed.  The requester thread is woken up (if still waiting),
277  * the 'end' callback is called if given, else the reference to the
278  * request is released
279  */
280 void fuse_request_end(struct fuse_req *req)
281 {
282         struct fuse_mount *fm = req->fm;
283         struct fuse_conn *fc = fm->fc;
284         struct fuse_iqueue *fiq = &fc->iq;
285
286         if (test_and_set_bit(FR_FINISHED, &req->flags))
287                 goto put_request;
288
289         /*
290          * test_and_set_bit() implies smp_mb() between bit
291          * changing and below FR_INTERRUPTED check. Pairs with
292          * smp_mb() from queue_interrupt().
293          */
294         if (test_bit(FR_INTERRUPTED, &req->flags)) {
295                 spin_lock(&fiq->lock);
296                 list_del_init(&req->intr_entry);
297                 spin_unlock(&fiq->lock);
298         }
299         WARN_ON(test_bit(FR_PENDING, &req->flags));
300         WARN_ON(test_bit(FR_SENT, &req->flags));
301         if (test_bit(FR_BACKGROUND, &req->flags)) {
302                 spin_lock(&fc->bg_lock);
303                 clear_bit(FR_BACKGROUND, &req->flags);
304                 if (fc->num_background == fc->max_background) {
305                         fc->blocked = 0;
306                         wake_up(&fc->blocked_waitq);
307                 } else if (!fc->blocked) {
308                         /*
309                          * Wake up next waiter, if any.  It's okay to use
310                          * waitqueue_active(), as we've already synced up
311                          * fc->blocked with waiters with the wake_up() call
312                          * above.
313                          */
314                         if (waitqueue_active(&fc->blocked_waitq))
315                                 wake_up(&fc->blocked_waitq);
316                 }
317
318                 fc->num_background--;
319                 fc->active_background--;
320                 flush_bg_queue(fc);
321                 spin_unlock(&fc->bg_lock);
322         } else {
323                 /* Wake up waiter sleeping in request_wait_answer() */
324                 wake_up(&req->waitq);
325         }
326
327         if (test_bit(FR_ASYNC, &req->flags))
328                 req->args->end(fm, req->args, req->out.h.error);
329 put_request:
330         fuse_put_request(req);
331 }
332 EXPORT_SYMBOL_GPL(fuse_request_end);
333
334 static int queue_interrupt(struct fuse_req *req)
335 {
336         struct fuse_iqueue *fiq = &req->fm->fc->iq;
337
338         spin_lock(&fiq->lock);
339         /* Check for we've sent request to interrupt this req */
340         if (unlikely(!test_bit(FR_INTERRUPTED, &req->flags))) {
341                 spin_unlock(&fiq->lock);
342                 return -EINVAL;
343         }
344
345         if (list_empty(&req->intr_entry)) {
346                 list_add_tail(&req->intr_entry, &fiq->interrupts);
347                 /*
348                  * Pairs with smp_mb() implied by test_and_set_bit()
349                  * from fuse_request_end().
350                  */
351                 smp_mb();
352                 if (test_bit(FR_FINISHED, &req->flags)) {
353                         list_del_init(&req->intr_entry);
354                         spin_unlock(&fiq->lock);
355                         return 0;
356                 }
357                 fiq->ops->wake_interrupt_and_unlock(fiq);
358         } else {
359                 spin_unlock(&fiq->lock);
360         }
361         return 0;
362 }
363
364 static void request_wait_answer(struct fuse_req *req)
365 {
366         struct fuse_conn *fc = req->fm->fc;
367         struct fuse_iqueue *fiq = &fc->iq;
368         int err;
369
370         if (!fc->no_interrupt) {
371                 /* Any signal may interrupt this */
372                 err = wait_event_interruptible(req->waitq,
373                                         test_bit(FR_FINISHED, &req->flags));
374                 if (!err)
375                         return;
376
377                 set_bit(FR_INTERRUPTED, &req->flags);
378                 /* matches barrier in fuse_dev_do_read() */
379                 smp_mb__after_atomic();
380                 if (test_bit(FR_SENT, &req->flags))
381                         queue_interrupt(req);
382         }
383
384         if (!test_bit(FR_FORCE, &req->flags)) {
385                 /* Only fatal signals may interrupt this */
386                 err = wait_event_killable(req->waitq,
387                                         test_bit(FR_FINISHED, &req->flags));
388                 if (!err)
389                         return;
390
391                 spin_lock(&fiq->lock);
392                 /* Request is not yet in userspace, bail out */
393                 if (test_bit(FR_PENDING, &req->flags)) {
394                         list_del(&req->list);
395                         spin_unlock(&fiq->lock);
396                         __fuse_put_request(req);
397                         req->out.h.error = -EINTR;
398                         return;
399                 }
400                 spin_unlock(&fiq->lock);
401         }
402
403         /*
404          * Either request is already in userspace, or it was forced.
405          * Wait it out.
406          */
407         wait_event(req->waitq, test_bit(FR_FINISHED, &req->flags));
408 }
409
410 static void __fuse_request_send(struct fuse_req *req)
411 {
412         struct fuse_iqueue *fiq = &req->fm->fc->iq;
413
414         BUG_ON(test_bit(FR_BACKGROUND, &req->flags));
415         spin_lock(&fiq->lock);
416         if (!fiq->connected) {
417                 spin_unlock(&fiq->lock);
418                 req->out.h.error = -ENOTCONN;
419         } else {
420                 req->in.h.unique = fuse_get_unique(fiq);
421                 /* acquire extra reference, since request is still needed
422                    after fuse_request_end() */
423                 __fuse_get_request(req);
424                 queue_request_and_unlock(fiq, req);
425
426                 request_wait_answer(req);
427                 /* Pairs with smp_wmb() in fuse_request_end() */
428                 smp_rmb();
429         }
430 }
431
432 static void fuse_adjust_compat(struct fuse_conn *fc, struct fuse_args *args)
433 {
434         if (fc->minor < 4 && args->opcode == FUSE_STATFS)
435                 args->out_args[0].size = FUSE_COMPAT_STATFS_SIZE;
436
437         if (fc->minor < 9) {
438                 switch (args->opcode) {
439                 case FUSE_LOOKUP:
440                 case FUSE_CREATE:
441                 case FUSE_MKNOD:
442                 case FUSE_MKDIR:
443                 case FUSE_SYMLINK:
444                 case FUSE_LINK:
445                         args->out_args[0].size = FUSE_COMPAT_ENTRY_OUT_SIZE;
446                         break;
447                 case FUSE_GETATTR:
448                 case FUSE_SETATTR:
449                         args->out_args[0].size = FUSE_COMPAT_ATTR_OUT_SIZE;
450                         break;
451                 }
452         }
453         if (fc->minor < 12) {
454                 switch (args->opcode) {
455                 case FUSE_CREATE:
456                         args->in_args[0].size = sizeof(struct fuse_open_in);
457                         break;
458                 case FUSE_MKNOD:
459                         args->in_args[0].size = FUSE_COMPAT_MKNOD_IN_SIZE;
460                         break;
461                 }
462         }
463 }
464
465 static void fuse_force_creds(struct fuse_req *req)
466 {
467         struct fuse_conn *fc = req->fm->fc;
468
469         req->in.h.uid = from_kuid_munged(fc->user_ns, current_fsuid());
470         req->in.h.gid = from_kgid_munged(fc->user_ns, current_fsgid());
471         req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns);
472 }
473
474 static void fuse_args_to_req(struct fuse_req *req, struct fuse_args *args)
475 {
476         req->in.h.opcode = args->opcode;
477         req->in.h.nodeid = args->nodeid;
478         req->args = args;
479         if (args->is_ext)
480                 req->in.h.total_extlen = args->in_args[args->ext_idx].size / 8;
481         if (args->end)
482                 __set_bit(FR_ASYNC, &req->flags);
483 }
484
485 ssize_t fuse_simple_request(struct fuse_mount *fm, struct fuse_args *args)
486 {
487         struct fuse_conn *fc = fm->fc;
488         struct fuse_req *req;
489         ssize_t ret;
490
491         if (args->force) {
492                 atomic_inc(&fc->num_waiting);
493                 req = fuse_request_alloc(fm, GFP_KERNEL | __GFP_NOFAIL);
494
495                 if (!args->nocreds)
496                         fuse_force_creds(req);
497
498                 __set_bit(FR_WAITING, &req->flags);
499                 __set_bit(FR_FORCE, &req->flags);
500         } else {
501                 WARN_ON(args->nocreds);
502                 req = fuse_get_req(fm, false);
503                 if (IS_ERR(req))
504                         return PTR_ERR(req);
505         }
506
507         /* Needs to be done after fuse_get_req() so that fc->minor is valid */
508         fuse_adjust_compat(fc, args);
509         fuse_args_to_req(req, args);
510
511         if (!args->noreply)
512                 __set_bit(FR_ISREPLY, &req->flags);
513         __fuse_request_send(req);
514         ret = req->out.h.error;
515         if (!ret && args->out_argvar) {
516                 BUG_ON(args->out_numargs == 0);
517                 ret = args->out_args[args->out_numargs - 1].size;
518         }
519         fuse_put_request(req);
520
521         return ret;
522 }
523
524 static bool fuse_request_queue_background(struct fuse_req *req)
525 {
526         struct fuse_mount *fm = req->fm;
527         struct fuse_conn *fc = fm->fc;
528         bool queued = false;
529
530         WARN_ON(!test_bit(FR_BACKGROUND, &req->flags));
531         if (!test_bit(FR_WAITING, &req->flags)) {
532                 __set_bit(FR_WAITING, &req->flags);
533                 atomic_inc(&fc->num_waiting);
534         }
535         __set_bit(FR_ISREPLY, &req->flags);
536         spin_lock(&fc->bg_lock);
537         if (likely(fc->connected)) {
538                 fc->num_background++;
539                 if (fc->num_background == fc->max_background)
540                         fc->blocked = 1;
541                 list_add_tail(&req->list, &fc->bg_queue);
542                 flush_bg_queue(fc);
543                 queued = true;
544         }
545         spin_unlock(&fc->bg_lock);
546
547         return queued;
548 }
549
550 int fuse_simple_background(struct fuse_mount *fm, struct fuse_args *args,
551                             gfp_t gfp_flags)
552 {
553         struct fuse_req *req;
554
555         if (args->force) {
556                 WARN_ON(!args->nocreds);
557                 req = fuse_request_alloc(fm, gfp_flags);
558                 if (!req)
559                         return -ENOMEM;
560                 __set_bit(FR_BACKGROUND, &req->flags);
561         } else {
562                 WARN_ON(args->nocreds);
563                 req = fuse_get_req(fm, true);
564                 if (IS_ERR(req))
565                         return PTR_ERR(req);
566         }
567
568         fuse_args_to_req(req, args);
569
570         if (!fuse_request_queue_background(req)) {
571                 fuse_put_request(req);
572                 return -ENOTCONN;
573         }
574
575         return 0;
576 }
577 EXPORT_SYMBOL_GPL(fuse_simple_background);
578
579 static int fuse_simple_notify_reply(struct fuse_mount *fm,
580                                     struct fuse_args *args, u64 unique)
581 {
582         struct fuse_req *req;
583         struct fuse_iqueue *fiq = &fm->fc->iq;
584         int err = 0;
585
586         req = fuse_get_req(fm, false);
587         if (IS_ERR(req))
588                 return PTR_ERR(req);
589
590         __clear_bit(FR_ISREPLY, &req->flags);
591         req->in.h.unique = unique;
592
593         fuse_args_to_req(req, args);
594
595         spin_lock(&fiq->lock);
596         if (fiq->connected) {
597                 queue_request_and_unlock(fiq, req);
598         } else {
599                 err = -ENODEV;
600                 spin_unlock(&fiq->lock);
601                 fuse_put_request(req);
602         }
603
604         return err;
605 }
606
607 /*
608  * Lock the request.  Up to the next unlock_request() there mustn't be
609  * anything that could cause a page-fault.  If the request was already
610  * aborted bail out.
611  */
612 static int lock_request(struct fuse_req *req)
613 {
614         int err = 0;
615         if (req) {
616                 spin_lock(&req->waitq.lock);
617                 if (test_bit(FR_ABORTED, &req->flags))
618                         err = -ENOENT;
619                 else
620                         set_bit(FR_LOCKED, &req->flags);
621                 spin_unlock(&req->waitq.lock);
622         }
623         return err;
624 }
625
626 /*
627  * Unlock request.  If it was aborted while locked, caller is responsible
628  * for unlocking and ending the request.
629  */
630 static int unlock_request(struct fuse_req *req)
631 {
632         int err = 0;
633         if (req) {
634                 spin_lock(&req->waitq.lock);
635                 if (test_bit(FR_ABORTED, &req->flags))
636                         err = -ENOENT;
637                 else
638                         clear_bit(FR_LOCKED, &req->flags);
639                 spin_unlock(&req->waitq.lock);
640         }
641         return err;
642 }
643
644 struct fuse_copy_state {
645         int write;
646         struct fuse_req *req;
647         struct iov_iter *iter;
648         struct pipe_buffer *pipebufs;
649         struct pipe_buffer *currbuf;
650         struct pipe_inode_info *pipe;
651         unsigned long nr_segs;
652         struct page *pg;
653         unsigned len;
654         unsigned offset;
655         unsigned move_pages:1;
656 };
657
658 static void fuse_copy_init(struct fuse_copy_state *cs, int write,
659                            struct iov_iter *iter)
660 {
661         memset(cs, 0, sizeof(*cs));
662         cs->write = write;
663         cs->iter = iter;
664 }
665
666 /* Unmap and put previous page of userspace buffer */
667 static void fuse_copy_finish(struct fuse_copy_state *cs)
668 {
669         if (cs->currbuf) {
670                 struct pipe_buffer *buf = cs->currbuf;
671
672                 if (cs->write)
673                         buf->len = PAGE_SIZE - cs->len;
674                 cs->currbuf = NULL;
675         } else if (cs->pg) {
676                 if (cs->write) {
677                         flush_dcache_page(cs->pg);
678                         set_page_dirty_lock(cs->pg);
679                 }
680                 put_page(cs->pg);
681         }
682         cs->pg = NULL;
683 }
684
685 /*
686  * Get another pagefull of userspace buffer, and map it to kernel
687  * address space, and lock request
688  */
689 static int fuse_copy_fill(struct fuse_copy_state *cs)
690 {
691         struct page *page;
692         int err;
693
694         err = unlock_request(cs->req);
695         if (err)
696                 return err;
697
698         fuse_copy_finish(cs);
699         if (cs->pipebufs) {
700                 struct pipe_buffer *buf = cs->pipebufs;
701
702                 if (!cs->write) {
703                         err = pipe_buf_confirm(cs->pipe, buf);
704                         if (err)
705                                 return err;
706
707                         BUG_ON(!cs->nr_segs);
708                         cs->currbuf = buf;
709                         cs->pg = buf->page;
710                         cs->offset = buf->offset;
711                         cs->len = buf->len;
712                         cs->pipebufs++;
713                         cs->nr_segs--;
714                 } else {
715                         if (cs->nr_segs >= cs->pipe->max_usage)
716                                 return -EIO;
717
718                         page = alloc_page(GFP_HIGHUSER);
719                         if (!page)
720                                 return -ENOMEM;
721
722                         buf->page = page;
723                         buf->offset = 0;
724                         buf->len = 0;
725
726                         cs->currbuf = buf;
727                         cs->pg = page;
728                         cs->offset = 0;
729                         cs->len = PAGE_SIZE;
730                         cs->pipebufs++;
731                         cs->nr_segs++;
732                 }
733         } else {
734                 size_t off;
735                 err = iov_iter_get_pages2(cs->iter, &page, PAGE_SIZE, 1, &off);
736                 if (err < 0)
737                         return err;
738                 BUG_ON(!err);
739                 cs->len = err;
740                 cs->offset = off;
741                 cs->pg = page;
742         }
743
744         return lock_request(cs->req);
745 }
746
747 /* Do as much copy to/from userspace buffer as we can */
748 static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
749 {
750         unsigned ncpy = min(*size, cs->len);
751         if (val) {
752                 void *pgaddr = kmap_local_page(cs->pg);
753                 void *buf = pgaddr + cs->offset;
754
755                 if (cs->write)
756                         memcpy(buf, *val, ncpy);
757                 else
758                         memcpy(*val, buf, ncpy);
759
760                 kunmap_local(pgaddr);
761                 *val += ncpy;
762         }
763         *size -= ncpy;
764         cs->len -= ncpy;
765         cs->offset += ncpy;
766         return ncpy;
767 }
768
769 static int fuse_check_folio(struct folio *folio)
770 {
771         if (folio_mapped(folio) ||
772             folio->mapping != NULL ||
773             (folio->flags & PAGE_FLAGS_CHECK_AT_PREP &
774              ~(1 << PG_locked |
775                1 << PG_referenced |
776                1 << PG_uptodate |
777                1 << PG_lru |
778                1 << PG_active |
779                1 << PG_workingset |
780                1 << PG_reclaim |
781                1 << PG_waiters |
782                LRU_GEN_MASK | LRU_REFS_MASK))) {
783                 dump_page(&folio->page, "fuse: trying to steal weird page");
784                 return 1;
785         }
786         return 0;
787 }
788
789 static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
790 {
791         int err;
792         struct folio *oldfolio = page_folio(*pagep);
793         struct folio *newfolio;
794         struct pipe_buffer *buf = cs->pipebufs;
795
796         folio_get(oldfolio);
797         err = unlock_request(cs->req);
798         if (err)
799                 goto out_put_old;
800
801         fuse_copy_finish(cs);
802
803         err = pipe_buf_confirm(cs->pipe, buf);
804         if (err)
805                 goto out_put_old;
806
807         BUG_ON(!cs->nr_segs);
808         cs->currbuf = buf;
809         cs->len = buf->len;
810         cs->pipebufs++;
811         cs->nr_segs--;
812
813         if (cs->len != PAGE_SIZE)
814                 goto out_fallback;
815
816         if (!pipe_buf_try_steal(cs->pipe, buf))
817                 goto out_fallback;
818
819         newfolio = page_folio(buf->page);
820
821         if (!folio_test_uptodate(newfolio))
822                 folio_mark_uptodate(newfolio);
823
824         folio_clear_mappedtodisk(newfolio);
825
826         if (fuse_check_folio(newfolio) != 0)
827                 goto out_fallback_unlock;
828
829         /*
830          * This is a new and locked page, it shouldn't be mapped or
831          * have any special flags on it
832          */
833         if (WARN_ON(folio_mapped(oldfolio)))
834                 goto out_fallback_unlock;
835         if (WARN_ON(folio_has_private(oldfolio)))
836                 goto out_fallback_unlock;
837         if (WARN_ON(folio_test_dirty(oldfolio) ||
838                                 folio_test_writeback(oldfolio)))
839                 goto out_fallback_unlock;
840         if (WARN_ON(folio_test_mlocked(oldfolio)))
841                 goto out_fallback_unlock;
842
843         replace_page_cache_folio(oldfolio, newfolio);
844
845         folio_get(newfolio);
846
847         if (!(buf->flags & PIPE_BUF_FLAG_LRU))
848                 folio_add_lru(newfolio);
849
850         /*
851          * Release while we have extra ref on stolen page.  Otherwise
852          * anon_pipe_buf_release() might think the page can be reused.
853          */
854         pipe_buf_release(cs->pipe, buf);
855
856         err = 0;
857         spin_lock(&cs->req->waitq.lock);
858         if (test_bit(FR_ABORTED, &cs->req->flags))
859                 err = -ENOENT;
860         else
861                 *pagep = &newfolio->page;
862         spin_unlock(&cs->req->waitq.lock);
863
864         if (err) {
865                 folio_unlock(newfolio);
866                 folio_put(newfolio);
867                 goto out_put_old;
868         }
869
870         folio_unlock(oldfolio);
871         /* Drop ref for ap->pages[] array */
872         folio_put(oldfolio);
873         cs->len = 0;
874
875         err = 0;
876 out_put_old:
877         /* Drop ref obtained in this function */
878         folio_put(oldfolio);
879         return err;
880
881 out_fallback_unlock:
882         folio_unlock(newfolio);
883 out_fallback:
884         cs->pg = buf->page;
885         cs->offset = buf->offset;
886
887         err = lock_request(cs->req);
888         if (!err)
889                 err = 1;
890
891         goto out_put_old;
892 }
893
894 static int fuse_ref_page(struct fuse_copy_state *cs, struct page *page,
895                          unsigned offset, unsigned count)
896 {
897         struct pipe_buffer *buf;
898         int err;
899
900         if (cs->nr_segs >= cs->pipe->max_usage)
901                 return -EIO;
902
903         get_page(page);
904         err = unlock_request(cs->req);
905         if (err) {
906                 put_page(page);
907                 return err;
908         }
909
910         fuse_copy_finish(cs);
911
912         buf = cs->pipebufs;
913         buf->page = page;
914         buf->offset = offset;
915         buf->len = count;
916
917         cs->pipebufs++;
918         cs->nr_segs++;
919         cs->len = 0;
920
921         return 0;
922 }
923
924 /*
925  * Copy a page in the request to/from the userspace buffer.  Must be
926  * done atomically
927  */
928 static int fuse_copy_page(struct fuse_copy_state *cs, struct page **pagep,
929                           unsigned offset, unsigned count, int zeroing)
930 {
931         int err;
932         struct page *page = *pagep;
933
934         if (page && zeroing && count < PAGE_SIZE)
935                 clear_highpage(page);
936
937         while (count) {
938                 if (cs->write && cs->pipebufs && page) {
939                         /*
940                          * Can't control lifetime of pipe buffers, so always
941                          * copy user pages.
942                          */
943                         if (cs->req->args->user_pages) {
944                                 err = fuse_copy_fill(cs);
945                                 if (err)
946                                         return err;
947                         } else {
948                                 return fuse_ref_page(cs, page, offset, count);
949                         }
950                 } else if (!cs->len) {
951                         if (cs->move_pages && page &&
952                             offset == 0 && count == PAGE_SIZE) {
953                                 err = fuse_try_move_page(cs, pagep);
954                                 if (err <= 0)
955                                         return err;
956                         } else {
957                                 err = fuse_copy_fill(cs);
958                                 if (err)
959                                         return err;
960                         }
961                 }
962                 if (page) {
963                         void *mapaddr = kmap_local_page(page);
964                         void *buf = mapaddr + offset;
965                         offset += fuse_copy_do(cs, &buf, &count);
966                         kunmap_local(mapaddr);
967                 } else
968                         offset += fuse_copy_do(cs, NULL, &count);
969         }
970         if (page && !cs->write)
971                 flush_dcache_page(page);
972         return 0;
973 }
974
975 /* Copy pages in the request to/from userspace buffer */
976 static int fuse_copy_pages(struct fuse_copy_state *cs, unsigned nbytes,
977                            int zeroing)
978 {
979         unsigned i;
980         struct fuse_req *req = cs->req;
981         struct fuse_args_pages *ap = container_of(req->args, typeof(*ap), args);
982
983
984         for (i = 0; i < ap->num_pages && (nbytes || zeroing); i++) {
985                 int err;
986                 unsigned int offset = ap->descs[i].offset;
987                 unsigned int count = min(nbytes, ap->descs[i].length);
988
989                 err = fuse_copy_page(cs, &ap->pages[i], offset, count, zeroing);
990                 if (err)
991                         return err;
992
993                 nbytes -= count;
994         }
995         return 0;
996 }
997
998 /* Copy a single argument in the request to/from userspace buffer */
999 static int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned size)
1000 {
1001         while (size) {
1002                 if (!cs->len) {
1003                         int err = fuse_copy_fill(cs);
1004                         if (err)
1005                                 return err;
1006                 }
1007                 fuse_copy_do(cs, &val, &size);
1008         }
1009         return 0;
1010 }
1011
1012 /* Copy request arguments to/from userspace buffer */
1013 static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs,
1014                           unsigned argpages, struct fuse_arg *args,
1015                           int zeroing)
1016 {
1017         int err = 0;
1018         unsigned i;
1019
1020         for (i = 0; !err && i < numargs; i++)  {
1021                 struct fuse_arg *arg = &args[i];
1022                 if (i == numargs - 1 && argpages)
1023                         err = fuse_copy_pages(cs, arg->size, zeroing);
1024                 else
1025                         err = fuse_copy_one(cs, arg->value, arg->size);
1026         }
1027         return err;
1028 }
1029
1030 static int forget_pending(struct fuse_iqueue *fiq)
1031 {
1032         return fiq->forget_list_head.next != NULL;
1033 }
1034
1035 static int request_pending(struct fuse_iqueue *fiq)
1036 {
1037         return !list_empty(&fiq->pending) || !list_empty(&fiq->interrupts) ||
1038                 forget_pending(fiq);
1039 }
1040
1041 /*
1042  * Transfer an interrupt request to userspace
1043  *
1044  * Unlike other requests this is assembled on demand, without a need
1045  * to allocate a separate fuse_req structure.
1046  *
1047  * Called with fiq->lock held, releases it
1048  */
1049 static int fuse_read_interrupt(struct fuse_iqueue *fiq,
1050                                struct fuse_copy_state *cs,
1051                                size_t nbytes, struct fuse_req *req)
1052 __releases(fiq->lock)
1053 {
1054         struct fuse_in_header ih;
1055         struct fuse_interrupt_in arg;
1056         unsigned reqsize = sizeof(ih) + sizeof(arg);
1057         int err;
1058
1059         list_del_init(&req->intr_entry);
1060         memset(&ih, 0, sizeof(ih));
1061         memset(&arg, 0, sizeof(arg));
1062         ih.len = reqsize;
1063         ih.opcode = FUSE_INTERRUPT;
1064         ih.unique = (req->in.h.unique | FUSE_INT_REQ_BIT);
1065         arg.unique = req->in.h.unique;
1066
1067         spin_unlock(&fiq->lock);
1068         if (nbytes < reqsize)
1069                 return -EINVAL;
1070
1071         err = fuse_copy_one(cs, &ih, sizeof(ih));
1072         if (!err)
1073                 err = fuse_copy_one(cs, &arg, sizeof(arg));
1074         fuse_copy_finish(cs);
1075
1076         return err ? err : reqsize;
1077 }
1078
1079 struct fuse_forget_link *fuse_dequeue_forget(struct fuse_iqueue *fiq,
1080                                              unsigned int max,
1081                                              unsigned int *countp)
1082 {
1083         struct fuse_forget_link *head = fiq->forget_list_head.next;
1084         struct fuse_forget_link **newhead = &head;
1085         unsigned count;
1086
1087         for (count = 0; *newhead != NULL && count < max; count++)
1088                 newhead = &(*newhead)->next;
1089
1090         fiq->forget_list_head.next = *newhead;
1091         *newhead = NULL;
1092         if (fiq->forget_list_head.next == NULL)
1093                 fiq->forget_list_tail = &fiq->forget_list_head;
1094
1095         if (countp != NULL)
1096                 *countp = count;
1097
1098         return head;
1099 }
1100 EXPORT_SYMBOL(fuse_dequeue_forget);
1101
1102 static int fuse_read_single_forget(struct fuse_iqueue *fiq,
1103                                    struct fuse_copy_state *cs,
1104                                    size_t nbytes)
1105 __releases(fiq->lock)
1106 {
1107         int err;
1108         struct fuse_forget_link *forget = fuse_dequeue_forget(fiq, 1, NULL);
1109         struct fuse_forget_in arg = {
1110                 .nlookup = forget->forget_one.nlookup,
1111         };
1112         struct fuse_in_header ih = {
1113                 .opcode = FUSE_FORGET,
1114                 .nodeid = forget->forget_one.nodeid,
1115                 .unique = fuse_get_unique(fiq),
1116                 .len = sizeof(ih) + sizeof(arg),
1117         };
1118
1119         spin_unlock(&fiq->lock);
1120         kfree(forget);
1121         if (nbytes < ih.len)
1122                 return -EINVAL;
1123
1124         err = fuse_copy_one(cs, &ih, sizeof(ih));
1125         if (!err)
1126                 err = fuse_copy_one(cs, &arg, sizeof(arg));
1127         fuse_copy_finish(cs);
1128
1129         if (err)
1130                 return err;
1131
1132         return ih.len;
1133 }
1134
1135 static int fuse_read_batch_forget(struct fuse_iqueue *fiq,
1136                                    struct fuse_copy_state *cs, size_t nbytes)
1137 __releases(fiq->lock)
1138 {
1139         int err;
1140         unsigned max_forgets;
1141         unsigned count;
1142         struct fuse_forget_link *head;
1143         struct fuse_batch_forget_in arg = { .count = 0 };
1144         struct fuse_in_header ih = {
1145                 .opcode = FUSE_BATCH_FORGET,
1146                 .unique = fuse_get_unique(fiq),
1147                 .len = sizeof(ih) + sizeof(arg),
1148         };
1149
1150         if (nbytes < ih.len) {
1151                 spin_unlock(&fiq->lock);
1152                 return -EINVAL;
1153         }
1154
1155         max_forgets = (nbytes - ih.len) / sizeof(struct fuse_forget_one);
1156         head = fuse_dequeue_forget(fiq, max_forgets, &count);
1157         spin_unlock(&fiq->lock);
1158
1159         arg.count = count;
1160         ih.len += count * sizeof(struct fuse_forget_one);
1161         err = fuse_copy_one(cs, &ih, sizeof(ih));
1162         if (!err)
1163                 err = fuse_copy_one(cs, &arg, sizeof(arg));
1164
1165         while (head) {
1166                 struct fuse_forget_link *forget = head;
1167
1168                 if (!err) {
1169                         err = fuse_copy_one(cs, &forget->forget_one,
1170                                             sizeof(forget->forget_one));
1171                 }
1172                 head = forget->next;
1173                 kfree(forget);
1174         }
1175
1176         fuse_copy_finish(cs);
1177
1178         if (err)
1179                 return err;
1180
1181         return ih.len;
1182 }
1183
1184 static int fuse_read_forget(struct fuse_conn *fc, struct fuse_iqueue *fiq,
1185                             struct fuse_copy_state *cs,
1186                             size_t nbytes)
1187 __releases(fiq->lock)
1188 {
1189         if (fc->minor < 16 || fiq->forget_list_head.next->next == NULL)
1190                 return fuse_read_single_forget(fiq, cs, nbytes);
1191         else
1192                 return fuse_read_batch_forget(fiq, cs, nbytes);
1193 }
1194
1195 /*
1196  * Read a single request into the userspace filesystem's buffer.  This
1197  * function waits until a request is available, then removes it from
1198  * the pending list and copies request data to userspace buffer.  If
1199  * no reply is needed (FORGET) or request has been aborted or there
1200  * was an error during the copying then it's finished by calling
1201  * fuse_request_end().  Otherwise add it to the processing list, and set
1202  * the 'sent' flag.
1203  */
1204 static ssize_t fuse_dev_do_read(struct fuse_dev *fud, struct file *file,
1205                                 struct fuse_copy_state *cs, size_t nbytes)
1206 {
1207         ssize_t err;
1208         struct fuse_conn *fc = fud->fc;
1209         struct fuse_iqueue *fiq = &fc->iq;
1210         struct fuse_pqueue *fpq = &fud->pq;
1211         struct fuse_req *req;
1212         struct fuse_args *args;
1213         unsigned reqsize;
1214         unsigned int hash;
1215
1216         /*
1217          * Require sane minimum read buffer - that has capacity for fixed part
1218          * of any request header + negotiated max_write room for data.
1219          *
1220          * Historically libfuse reserves 4K for fixed header room, but e.g.
1221          * GlusterFS reserves only 80 bytes
1222          *
1223          *      = `sizeof(fuse_in_header) + sizeof(fuse_write_in)`
1224          *
1225          * which is the absolute minimum any sane filesystem should be using
1226          * for header room.
1227          */
1228         if (nbytes < max_t(size_t, FUSE_MIN_READ_BUFFER,
1229                            sizeof(struct fuse_in_header) +
1230                            sizeof(struct fuse_write_in) +
1231                            fc->max_write))
1232                 return -EINVAL;
1233
1234  restart:
1235         for (;;) {
1236                 spin_lock(&fiq->lock);
1237                 if (!fiq->connected || request_pending(fiq))
1238                         break;
1239                 spin_unlock(&fiq->lock);
1240
1241                 if (file->f_flags & O_NONBLOCK)
1242                         return -EAGAIN;
1243                 err = wait_event_interruptible_exclusive(fiq->waitq,
1244                                 !fiq->connected || request_pending(fiq));
1245                 if (err)
1246                         return err;
1247         }
1248
1249         if (!fiq->connected) {
1250                 err = fc->aborted ? -ECONNABORTED : -ENODEV;
1251                 goto err_unlock;
1252         }
1253
1254         if (!list_empty(&fiq->interrupts)) {
1255                 req = list_entry(fiq->interrupts.next, struct fuse_req,
1256                                  intr_entry);
1257                 return fuse_read_interrupt(fiq, cs, nbytes, req);
1258         }
1259
1260         if (forget_pending(fiq)) {
1261                 if (list_empty(&fiq->pending) || fiq->forget_batch-- > 0)
1262                         return fuse_read_forget(fc, fiq, cs, nbytes);
1263
1264                 if (fiq->forget_batch <= -8)
1265                         fiq->forget_batch = 16;
1266         }
1267
1268         req = list_entry(fiq->pending.next, struct fuse_req, list);
1269         clear_bit(FR_PENDING, &req->flags);
1270         list_del_init(&req->list);
1271         spin_unlock(&fiq->lock);
1272
1273         args = req->args;
1274         reqsize = req->in.h.len;
1275
1276         /* If request is too large, reply with an error and restart the read */
1277         if (nbytes < reqsize) {
1278                 req->out.h.error = -EIO;
1279                 /* SETXATTR is special, since it may contain too large data */
1280                 if (args->opcode == FUSE_SETXATTR)
1281                         req->out.h.error = -E2BIG;
1282                 fuse_request_end(req);
1283                 goto restart;
1284         }
1285         spin_lock(&fpq->lock);
1286         /*
1287          *  Must not put request on fpq->io queue after having been shut down by
1288          *  fuse_abort_conn()
1289          */
1290         if (!fpq->connected) {
1291                 req->out.h.error = err = -ECONNABORTED;
1292                 goto out_end;
1293
1294         }
1295         list_add(&req->list, &fpq->io);
1296         spin_unlock(&fpq->lock);
1297         cs->req = req;
1298         err = fuse_copy_one(cs, &req->in.h, sizeof(req->in.h));
1299         if (!err)
1300                 err = fuse_copy_args(cs, args->in_numargs, args->in_pages,
1301                                      (struct fuse_arg *) args->in_args, 0);
1302         fuse_copy_finish(cs);
1303         spin_lock(&fpq->lock);
1304         clear_bit(FR_LOCKED, &req->flags);
1305         if (!fpq->connected) {
1306                 err = fc->aborted ? -ECONNABORTED : -ENODEV;
1307                 goto out_end;
1308         }
1309         if (err) {
1310                 req->out.h.error = -EIO;
1311                 goto out_end;
1312         }
1313         if (!test_bit(FR_ISREPLY, &req->flags)) {
1314                 err = reqsize;
1315                 goto out_end;
1316         }
1317         hash = fuse_req_hash(req->in.h.unique);
1318         list_move_tail(&req->list, &fpq->processing[hash]);
1319         __fuse_get_request(req);
1320         set_bit(FR_SENT, &req->flags);
1321         spin_unlock(&fpq->lock);
1322         /* matches barrier in request_wait_answer() */
1323         smp_mb__after_atomic();
1324         if (test_bit(FR_INTERRUPTED, &req->flags))
1325                 queue_interrupt(req);
1326         fuse_put_request(req);
1327
1328         return reqsize;
1329
1330 out_end:
1331         if (!test_bit(FR_PRIVATE, &req->flags))
1332                 list_del_init(&req->list);
1333         spin_unlock(&fpq->lock);
1334         fuse_request_end(req);
1335         return err;
1336
1337  err_unlock:
1338         spin_unlock(&fiq->lock);
1339         return err;
1340 }
1341
1342 static int fuse_dev_open(struct inode *inode, struct file *file)
1343 {
1344         /*
1345          * The fuse device's file's private_data is used to hold
1346          * the fuse_conn(ection) when it is mounted, and is used to
1347          * keep track of whether the file has been mounted already.
1348          */
1349         file->private_data = NULL;
1350         return 0;
1351 }
1352
1353 static ssize_t fuse_dev_read(struct kiocb *iocb, struct iov_iter *to)
1354 {
1355         struct fuse_copy_state cs;
1356         struct file *file = iocb->ki_filp;
1357         struct fuse_dev *fud = fuse_get_dev(file);
1358
1359         if (!fud)
1360                 return -EPERM;
1361
1362         if (!user_backed_iter(to))
1363                 return -EINVAL;
1364
1365         fuse_copy_init(&cs, 1, to);
1366
1367         return fuse_dev_do_read(fud, file, &cs, iov_iter_count(to));
1368 }
1369
1370 static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
1371                                     struct pipe_inode_info *pipe,
1372                                     size_t len, unsigned int flags)
1373 {
1374         int total, ret;
1375         int page_nr = 0;
1376         struct pipe_buffer *bufs;
1377         struct fuse_copy_state cs;
1378         struct fuse_dev *fud = fuse_get_dev(in);
1379
1380         if (!fud)
1381                 return -EPERM;
1382
1383         bufs = kvmalloc_array(pipe->max_usage, sizeof(struct pipe_buffer),
1384                               GFP_KERNEL);
1385         if (!bufs)
1386                 return -ENOMEM;
1387
1388         fuse_copy_init(&cs, 1, NULL);
1389         cs.pipebufs = bufs;
1390         cs.pipe = pipe;
1391         ret = fuse_dev_do_read(fud, in, &cs, len);
1392         if (ret < 0)
1393                 goto out;
1394
1395         if (pipe_occupancy(pipe->head, pipe->tail) + cs.nr_segs > pipe->max_usage) {
1396                 ret = -EIO;
1397                 goto out;
1398         }
1399
1400         for (ret = total = 0; page_nr < cs.nr_segs; total += ret) {
1401                 /*
1402                  * Need to be careful about this.  Having buf->ops in module
1403                  * code can Oops if the buffer persists after module unload.
1404                  */
1405                 bufs[page_nr].ops = &nosteal_pipe_buf_ops;
1406                 bufs[page_nr].flags = 0;
1407                 ret = add_to_pipe(pipe, &bufs[page_nr++]);
1408                 if (unlikely(ret < 0))
1409                         break;
1410         }
1411         if (total)
1412                 ret = total;
1413 out:
1414         for (; page_nr < cs.nr_segs; page_nr++)
1415                 put_page(bufs[page_nr].page);
1416
1417         kvfree(bufs);
1418         return ret;
1419 }
1420
1421 static int fuse_notify_poll(struct fuse_conn *fc, unsigned int size,
1422                             struct fuse_copy_state *cs)
1423 {
1424         struct fuse_notify_poll_wakeup_out outarg;
1425         int err = -EINVAL;
1426
1427         if (size != sizeof(outarg))
1428                 goto err;
1429
1430         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1431         if (err)
1432                 goto err;
1433
1434         fuse_copy_finish(cs);
1435         return fuse_notify_poll_wakeup(fc, &outarg);
1436
1437 err:
1438         fuse_copy_finish(cs);
1439         return err;
1440 }
1441
1442 static int fuse_notify_inval_inode(struct fuse_conn *fc, unsigned int size,
1443                                    struct fuse_copy_state *cs)
1444 {
1445         struct fuse_notify_inval_inode_out outarg;
1446         int err = -EINVAL;
1447
1448         if (size != sizeof(outarg))
1449                 goto err;
1450
1451         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1452         if (err)
1453                 goto err;
1454         fuse_copy_finish(cs);
1455
1456         down_read(&fc->killsb);
1457         err = fuse_reverse_inval_inode(fc, outarg.ino,
1458                                        outarg.off, outarg.len);
1459         up_read(&fc->killsb);
1460         return err;
1461
1462 err:
1463         fuse_copy_finish(cs);
1464         return err;
1465 }
1466
1467 static int fuse_notify_inval_entry(struct fuse_conn *fc, unsigned int size,
1468                                    struct fuse_copy_state *cs)
1469 {
1470         struct fuse_notify_inval_entry_out outarg;
1471         int err = -ENOMEM;
1472         char *buf;
1473         struct qstr name;
1474
1475         buf = kzalloc(FUSE_NAME_MAX + 1, GFP_KERNEL);
1476         if (!buf)
1477                 goto err;
1478
1479         err = -EINVAL;
1480         if (size < sizeof(outarg))
1481                 goto err;
1482
1483         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1484         if (err)
1485                 goto err;
1486
1487         err = -ENAMETOOLONG;
1488         if (outarg.namelen > FUSE_NAME_MAX)
1489                 goto err;
1490
1491         err = -EINVAL;
1492         if (size != sizeof(outarg) + outarg.namelen + 1)
1493                 goto err;
1494
1495         name.name = buf;
1496         name.len = outarg.namelen;
1497         err = fuse_copy_one(cs, buf, outarg.namelen + 1);
1498         if (err)
1499                 goto err;
1500         fuse_copy_finish(cs);
1501         buf[outarg.namelen] = 0;
1502
1503         down_read(&fc->killsb);
1504         err = fuse_reverse_inval_entry(fc, outarg.parent, 0, &name, outarg.flags);
1505         up_read(&fc->killsb);
1506         kfree(buf);
1507         return err;
1508
1509 err:
1510         kfree(buf);
1511         fuse_copy_finish(cs);
1512         return err;
1513 }
1514
1515 static int fuse_notify_delete(struct fuse_conn *fc, unsigned int size,
1516                               struct fuse_copy_state *cs)
1517 {
1518         struct fuse_notify_delete_out outarg;
1519         int err = -ENOMEM;
1520         char *buf;
1521         struct qstr name;
1522
1523         buf = kzalloc(FUSE_NAME_MAX + 1, GFP_KERNEL);
1524         if (!buf)
1525                 goto err;
1526
1527         err = -EINVAL;
1528         if (size < sizeof(outarg))
1529                 goto err;
1530
1531         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1532         if (err)
1533                 goto err;
1534
1535         err = -ENAMETOOLONG;
1536         if (outarg.namelen > FUSE_NAME_MAX)
1537                 goto err;
1538
1539         err = -EINVAL;
1540         if (size != sizeof(outarg) + outarg.namelen + 1)
1541                 goto err;
1542
1543         name.name = buf;
1544         name.len = outarg.namelen;
1545         err = fuse_copy_one(cs, buf, outarg.namelen + 1);
1546         if (err)
1547                 goto err;
1548         fuse_copy_finish(cs);
1549         buf[outarg.namelen] = 0;
1550
1551         down_read(&fc->killsb);
1552         err = fuse_reverse_inval_entry(fc, outarg.parent, outarg.child, &name, 0);
1553         up_read(&fc->killsb);
1554         kfree(buf);
1555         return err;
1556
1557 err:
1558         kfree(buf);
1559         fuse_copy_finish(cs);
1560         return err;
1561 }
1562
1563 static int fuse_notify_store(struct fuse_conn *fc, unsigned int size,
1564                              struct fuse_copy_state *cs)
1565 {
1566         struct fuse_notify_store_out outarg;
1567         struct inode *inode;
1568         struct address_space *mapping;
1569         u64 nodeid;
1570         int err;
1571         pgoff_t index;
1572         unsigned int offset;
1573         unsigned int num;
1574         loff_t file_size;
1575         loff_t end;
1576
1577         err = -EINVAL;
1578         if (size < sizeof(outarg))
1579                 goto out_finish;
1580
1581         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1582         if (err)
1583                 goto out_finish;
1584
1585         err = -EINVAL;
1586         if (size - sizeof(outarg) != outarg.size)
1587                 goto out_finish;
1588
1589         nodeid = outarg.nodeid;
1590
1591         down_read(&fc->killsb);
1592
1593         err = -ENOENT;
1594         inode = fuse_ilookup(fc, nodeid,  NULL);
1595         if (!inode)
1596                 goto out_up_killsb;
1597
1598         mapping = inode->i_mapping;
1599         index = outarg.offset >> PAGE_SHIFT;
1600         offset = outarg.offset & ~PAGE_MASK;
1601         file_size = i_size_read(inode);
1602         end = outarg.offset + outarg.size;
1603         if (end > file_size) {
1604                 file_size = end;
1605                 fuse_write_update_attr(inode, file_size, outarg.size);
1606         }
1607
1608         num = outarg.size;
1609         while (num) {
1610                 struct page *page;
1611                 unsigned int this_num;
1612
1613                 err = -ENOMEM;
1614                 page = find_or_create_page(mapping, index,
1615                                            mapping_gfp_mask(mapping));
1616                 if (!page)
1617                         goto out_iput;
1618
1619                 this_num = min_t(unsigned, num, PAGE_SIZE - offset);
1620                 err = fuse_copy_page(cs, &page, offset, this_num, 0);
1621                 if (!err && offset == 0 &&
1622                     (this_num == PAGE_SIZE || file_size == end))
1623                         SetPageUptodate(page);
1624                 unlock_page(page);
1625                 put_page(page);
1626
1627                 if (err)
1628                         goto out_iput;
1629
1630                 num -= this_num;
1631                 offset = 0;
1632                 index++;
1633         }
1634
1635         err = 0;
1636
1637 out_iput:
1638         iput(inode);
1639 out_up_killsb:
1640         up_read(&fc->killsb);
1641 out_finish:
1642         fuse_copy_finish(cs);
1643         return err;
1644 }
1645
1646 struct fuse_retrieve_args {
1647         struct fuse_args_pages ap;
1648         struct fuse_notify_retrieve_in inarg;
1649 };
1650
1651 static void fuse_retrieve_end(struct fuse_mount *fm, struct fuse_args *args,
1652                               int error)
1653 {
1654         struct fuse_retrieve_args *ra =
1655                 container_of(args, typeof(*ra), ap.args);
1656
1657         release_pages(ra->ap.pages, ra->ap.num_pages);
1658         kfree(ra);
1659 }
1660
1661 static int fuse_retrieve(struct fuse_mount *fm, struct inode *inode,
1662                          struct fuse_notify_retrieve_out *outarg)
1663 {
1664         int err;
1665         struct address_space *mapping = inode->i_mapping;
1666         pgoff_t index;
1667         loff_t file_size;
1668         unsigned int num;
1669         unsigned int offset;
1670         size_t total_len = 0;
1671         unsigned int num_pages;
1672         struct fuse_conn *fc = fm->fc;
1673         struct fuse_retrieve_args *ra;
1674         size_t args_size = sizeof(*ra);
1675         struct fuse_args_pages *ap;
1676         struct fuse_args *args;
1677
1678         offset = outarg->offset & ~PAGE_MASK;
1679         file_size = i_size_read(inode);
1680
1681         num = min(outarg->size, fc->max_write);
1682         if (outarg->offset > file_size)
1683                 num = 0;
1684         else if (outarg->offset + num > file_size)
1685                 num = file_size - outarg->offset;
1686
1687         num_pages = (num + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
1688         num_pages = min(num_pages, fc->max_pages);
1689
1690         args_size += num_pages * (sizeof(ap->pages[0]) + sizeof(ap->descs[0]));
1691
1692         ra = kzalloc(args_size, GFP_KERNEL);
1693         if (!ra)
1694                 return -ENOMEM;
1695
1696         ap = &ra->ap;
1697         ap->pages = (void *) (ra + 1);
1698         ap->descs = (void *) (ap->pages + num_pages);
1699
1700         args = &ap->args;
1701         args->nodeid = outarg->nodeid;
1702         args->opcode = FUSE_NOTIFY_REPLY;
1703         args->in_numargs = 2;
1704         args->in_pages = true;
1705         args->end = fuse_retrieve_end;
1706
1707         index = outarg->offset >> PAGE_SHIFT;
1708
1709         while (num && ap->num_pages < num_pages) {
1710                 struct page *page;
1711                 unsigned int this_num;
1712
1713                 page = find_get_page(mapping, index);
1714                 if (!page)
1715                         break;
1716
1717                 this_num = min_t(unsigned, num, PAGE_SIZE - offset);
1718                 ap->pages[ap->num_pages] = page;
1719                 ap->descs[ap->num_pages].offset = offset;
1720                 ap->descs[ap->num_pages].length = this_num;
1721                 ap->num_pages++;
1722
1723                 offset = 0;
1724                 num -= this_num;
1725                 total_len += this_num;
1726                 index++;
1727         }
1728         ra->inarg.offset = outarg->offset;
1729         ra->inarg.size = total_len;
1730         args->in_args[0].size = sizeof(ra->inarg);
1731         args->in_args[0].value = &ra->inarg;
1732         args->in_args[1].size = total_len;
1733
1734         err = fuse_simple_notify_reply(fm, args, outarg->notify_unique);
1735         if (err)
1736                 fuse_retrieve_end(fm, args, err);
1737
1738         return err;
1739 }
1740
1741 static int fuse_notify_retrieve(struct fuse_conn *fc, unsigned int size,
1742                                 struct fuse_copy_state *cs)
1743 {
1744         struct fuse_notify_retrieve_out outarg;
1745         struct fuse_mount *fm;
1746         struct inode *inode;
1747         u64 nodeid;
1748         int err;
1749
1750         err = -EINVAL;
1751         if (size != sizeof(outarg))
1752                 goto copy_finish;
1753
1754         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1755         if (err)
1756                 goto copy_finish;
1757
1758         fuse_copy_finish(cs);
1759
1760         down_read(&fc->killsb);
1761         err = -ENOENT;
1762         nodeid = outarg.nodeid;
1763
1764         inode = fuse_ilookup(fc, nodeid, &fm);
1765         if (inode) {
1766                 err = fuse_retrieve(fm, inode, &outarg);
1767                 iput(inode);
1768         }
1769         up_read(&fc->killsb);
1770
1771         return err;
1772
1773 copy_finish:
1774         fuse_copy_finish(cs);
1775         return err;
1776 }
1777
1778 static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
1779                        unsigned int size, struct fuse_copy_state *cs)
1780 {
1781         /* Don't try to move pages (yet) */
1782         cs->move_pages = 0;
1783
1784         switch (code) {
1785         case FUSE_NOTIFY_POLL:
1786                 return fuse_notify_poll(fc, size, cs);
1787
1788         case FUSE_NOTIFY_INVAL_INODE:
1789                 return fuse_notify_inval_inode(fc, size, cs);
1790
1791         case FUSE_NOTIFY_INVAL_ENTRY:
1792                 return fuse_notify_inval_entry(fc, size, cs);
1793
1794         case FUSE_NOTIFY_STORE:
1795                 return fuse_notify_store(fc, size, cs);
1796
1797         case FUSE_NOTIFY_RETRIEVE:
1798                 return fuse_notify_retrieve(fc, size, cs);
1799
1800         case FUSE_NOTIFY_DELETE:
1801                 return fuse_notify_delete(fc, size, cs);
1802
1803         default:
1804                 fuse_copy_finish(cs);
1805                 return -EINVAL;
1806         }
1807 }
1808
1809 /* Look up request on processing list by unique ID */
1810 static struct fuse_req *request_find(struct fuse_pqueue *fpq, u64 unique)
1811 {
1812         unsigned int hash = fuse_req_hash(unique);
1813         struct fuse_req *req;
1814
1815         list_for_each_entry(req, &fpq->processing[hash], list) {
1816                 if (req->in.h.unique == unique)
1817                         return req;
1818         }
1819         return NULL;
1820 }
1821
1822 static int copy_out_args(struct fuse_copy_state *cs, struct fuse_args *args,
1823                          unsigned nbytes)
1824 {
1825         unsigned reqsize = sizeof(struct fuse_out_header);
1826
1827         reqsize += fuse_len_args(args->out_numargs, args->out_args);
1828
1829         if (reqsize < nbytes || (reqsize > nbytes && !args->out_argvar))
1830                 return -EINVAL;
1831         else if (reqsize > nbytes) {
1832                 struct fuse_arg *lastarg = &args->out_args[args->out_numargs-1];
1833                 unsigned diffsize = reqsize - nbytes;
1834
1835                 if (diffsize > lastarg->size)
1836                         return -EINVAL;
1837                 lastarg->size -= diffsize;
1838         }
1839         return fuse_copy_args(cs, args->out_numargs, args->out_pages,
1840                               args->out_args, args->page_zeroing);
1841 }
1842
1843 /*
1844  * Write a single reply to a request.  First the header is copied from
1845  * the write buffer.  The request is then searched on the processing
1846  * list by the unique ID found in the header.  If found, then remove
1847  * it from the list and copy the rest of the buffer to the request.
1848  * The request is finished by calling fuse_request_end().
1849  */
1850 static ssize_t fuse_dev_do_write(struct fuse_dev *fud,
1851                                  struct fuse_copy_state *cs, size_t nbytes)
1852 {
1853         int err;
1854         struct fuse_conn *fc = fud->fc;
1855         struct fuse_pqueue *fpq = &fud->pq;
1856         struct fuse_req *req;
1857         struct fuse_out_header oh;
1858
1859         err = -EINVAL;
1860         if (nbytes < sizeof(struct fuse_out_header))
1861                 goto out;
1862
1863         err = fuse_copy_one(cs, &oh, sizeof(oh));
1864         if (err)
1865                 goto copy_finish;
1866
1867         err = -EINVAL;
1868         if (oh.len != nbytes)
1869                 goto copy_finish;
1870
1871         /*
1872          * Zero oh.unique indicates unsolicited notification message
1873          * and error contains notification code.
1874          */
1875         if (!oh.unique) {
1876                 err = fuse_notify(fc, oh.error, nbytes - sizeof(oh), cs);
1877                 goto out;
1878         }
1879
1880         err = -EINVAL;
1881         if (oh.error <= -512 || oh.error > 0)
1882                 goto copy_finish;
1883
1884         spin_lock(&fpq->lock);
1885         req = NULL;
1886         if (fpq->connected)
1887                 req = request_find(fpq, oh.unique & ~FUSE_INT_REQ_BIT);
1888
1889         err = -ENOENT;
1890         if (!req) {
1891                 spin_unlock(&fpq->lock);
1892                 goto copy_finish;
1893         }
1894
1895         /* Is it an interrupt reply ID? */
1896         if (oh.unique & FUSE_INT_REQ_BIT) {
1897                 __fuse_get_request(req);
1898                 spin_unlock(&fpq->lock);
1899
1900                 err = 0;
1901                 if (nbytes != sizeof(struct fuse_out_header))
1902                         err = -EINVAL;
1903                 else if (oh.error == -ENOSYS)
1904                         fc->no_interrupt = 1;
1905                 else if (oh.error == -EAGAIN)
1906                         err = queue_interrupt(req);
1907
1908                 fuse_put_request(req);
1909
1910                 goto copy_finish;
1911         }
1912
1913         clear_bit(FR_SENT, &req->flags);
1914         list_move(&req->list, &fpq->io);
1915         req->out.h = oh;
1916         set_bit(FR_LOCKED, &req->flags);
1917         spin_unlock(&fpq->lock);
1918         cs->req = req;
1919         if (!req->args->page_replace)
1920                 cs->move_pages = 0;
1921
1922         if (oh.error)
1923                 err = nbytes != sizeof(oh) ? -EINVAL : 0;
1924         else
1925                 err = copy_out_args(cs, req->args, nbytes);
1926         fuse_copy_finish(cs);
1927
1928         spin_lock(&fpq->lock);
1929         clear_bit(FR_LOCKED, &req->flags);
1930         if (!fpq->connected)
1931                 err = -ENOENT;
1932         else if (err)
1933                 req->out.h.error = -EIO;
1934         if (!test_bit(FR_PRIVATE, &req->flags))
1935                 list_del_init(&req->list);
1936         spin_unlock(&fpq->lock);
1937
1938         fuse_request_end(req);
1939 out:
1940         return err ? err : nbytes;
1941
1942 copy_finish:
1943         fuse_copy_finish(cs);
1944         goto out;
1945 }
1946
1947 static ssize_t fuse_dev_write(struct kiocb *iocb, struct iov_iter *from)
1948 {
1949         struct fuse_copy_state cs;
1950         struct fuse_dev *fud = fuse_get_dev(iocb->ki_filp);
1951
1952         if (!fud)
1953                 return -EPERM;
1954
1955         if (!user_backed_iter(from))
1956                 return -EINVAL;
1957
1958         fuse_copy_init(&cs, 0, from);
1959
1960         return fuse_dev_do_write(fud, &cs, iov_iter_count(from));
1961 }
1962
1963 static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
1964                                      struct file *out, loff_t *ppos,
1965                                      size_t len, unsigned int flags)
1966 {
1967         unsigned int head, tail, mask, count;
1968         unsigned nbuf;
1969         unsigned idx;
1970         struct pipe_buffer *bufs;
1971         struct fuse_copy_state cs;
1972         struct fuse_dev *fud;
1973         size_t rem;
1974         ssize_t ret;
1975
1976         fud = fuse_get_dev(out);
1977         if (!fud)
1978                 return -EPERM;
1979
1980         pipe_lock(pipe);
1981
1982         head = pipe->head;
1983         tail = pipe->tail;
1984         mask = pipe->ring_size - 1;
1985         count = head - tail;
1986
1987         bufs = kvmalloc_array(count, sizeof(struct pipe_buffer), GFP_KERNEL);
1988         if (!bufs) {
1989                 pipe_unlock(pipe);
1990                 return -ENOMEM;
1991         }
1992
1993         nbuf = 0;
1994         rem = 0;
1995         for (idx = tail; idx != head && rem < len; idx++)
1996                 rem += pipe->bufs[idx & mask].len;
1997
1998         ret = -EINVAL;
1999         if (rem < len)
2000                 goto out_free;
2001
2002         rem = len;
2003         while (rem) {
2004                 struct pipe_buffer *ibuf;
2005                 struct pipe_buffer *obuf;
2006
2007                 if (WARN_ON(nbuf >= count || tail == head))
2008                         goto out_free;
2009
2010                 ibuf = &pipe->bufs[tail & mask];
2011                 obuf = &bufs[nbuf];
2012
2013                 if (rem >= ibuf->len) {
2014                         *obuf = *ibuf;
2015                         ibuf->ops = NULL;
2016                         tail++;
2017                         pipe->tail = tail;
2018                 } else {
2019                         if (!pipe_buf_get(pipe, ibuf))
2020                                 goto out_free;
2021
2022                         *obuf = *ibuf;
2023                         obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
2024                         obuf->len = rem;
2025                         ibuf->offset += obuf->len;
2026                         ibuf->len -= obuf->len;
2027                 }
2028                 nbuf++;
2029                 rem -= obuf->len;
2030         }
2031         pipe_unlock(pipe);
2032
2033         fuse_copy_init(&cs, 0, NULL);
2034         cs.pipebufs = bufs;
2035         cs.nr_segs = nbuf;
2036         cs.pipe = pipe;
2037
2038         if (flags & SPLICE_F_MOVE)
2039                 cs.move_pages = 1;
2040
2041         ret = fuse_dev_do_write(fud, &cs, len);
2042
2043         pipe_lock(pipe);
2044 out_free:
2045         for (idx = 0; idx < nbuf; idx++) {
2046                 struct pipe_buffer *buf = &bufs[idx];
2047
2048                 if (buf->ops)
2049                         pipe_buf_release(pipe, buf);
2050         }
2051         pipe_unlock(pipe);
2052
2053         kvfree(bufs);
2054         return ret;
2055 }
2056
2057 static __poll_t fuse_dev_poll(struct file *file, poll_table *wait)
2058 {
2059         __poll_t mask = EPOLLOUT | EPOLLWRNORM;
2060         struct fuse_iqueue *fiq;
2061         struct fuse_dev *fud = fuse_get_dev(file);
2062
2063         if (!fud)
2064                 return EPOLLERR;
2065
2066         fiq = &fud->fc->iq;
2067         poll_wait(file, &fiq->waitq, wait);
2068
2069         spin_lock(&fiq->lock);
2070         if (!fiq->connected)
2071                 mask = EPOLLERR;
2072         else if (request_pending(fiq))
2073                 mask |= EPOLLIN | EPOLLRDNORM;
2074         spin_unlock(&fiq->lock);
2075
2076         return mask;
2077 }
2078
2079 /* Abort all requests on the given list (pending or processing) */
2080 static void end_requests(struct list_head *head)
2081 {
2082         while (!list_empty(head)) {
2083                 struct fuse_req *req;
2084                 req = list_entry(head->next, struct fuse_req, list);
2085                 req->out.h.error = -ECONNABORTED;
2086                 clear_bit(FR_SENT, &req->flags);
2087                 list_del_init(&req->list);
2088                 fuse_request_end(req);
2089         }
2090 }
2091
2092 static void end_polls(struct fuse_conn *fc)
2093 {
2094         struct rb_node *p;
2095
2096         p = rb_first(&fc->polled_files);
2097
2098         while (p) {
2099                 struct fuse_file *ff;
2100                 ff = rb_entry(p, struct fuse_file, polled_node);
2101                 wake_up_interruptible_all(&ff->poll_wait);
2102
2103                 p = rb_next(p);
2104         }
2105 }
2106
2107 /*
2108  * Abort all requests.
2109  *
2110  * Emergency exit in case of a malicious or accidental deadlock, or just a hung
2111  * filesystem.
2112  *
2113  * The same effect is usually achievable through killing the filesystem daemon
2114  * and all users of the filesystem.  The exception is the combination of an
2115  * asynchronous request and the tricky deadlock (see
2116  * Documentation/filesystems/fuse.rst).
2117  *
2118  * Aborting requests under I/O goes as follows: 1: Separate out unlocked
2119  * requests, they should be finished off immediately.  Locked requests will be
2120  * finished after unlock; see unlock_request(). 2: Finish off the unlocked
2121  * requests.  It is possible that some request will finish before we can.  This
2122  * is OK, the request will in that case be removed from the list before we touch
2123  * it.
2124  */
2125 void fuse_abort_conn(struct fuse_conn *fc)
2126 {
2127         struct fuse_iqueue *fiq = &fc->iq;
2128
2129         spin_lock(&fc->lock);
2130         if (fc->connected) {
2131                 struct fuse_dev *fud;
2132                 struct fuse_req *req, *next;
2133                 LIST_HEAD(to_end);
2134                 unsigned int i;
2135
2136                 /* Background queuing checks fc->connected under bg_lock */
2137                 spin_lock(&fc->bg_lock);
2138                 fc->connected = 0;
2139                 spin_unlock(&fc->bg_lock);
2140
2141                 fuse_set_initialized(fc);
2142                 list_for_each_entry(fud, &fc->devices, entry) {
2143                         struct fuse_pqueue *fpq = &fud->pq;
2144
2145                         spin_lock(&fpq->lock);
2146                         fpq->connected = 0;
2147                         list_for_each_entry_safe(req, next, &fpq->io, list) {
2148                                 req->out.h.error = -ECONNABORTED;
2149                                 spin_lock(&req->waitq.lock);
2150                                 set_bit(FR_ABORTED, &req->flags);
2151                                 if (!test_bit(FR_LOCKED, &req->flags)) {
2152                                         set_bit(FR_PRIVATE, &req->flags);
2153                                         __fuse_get_request(req);
2154                                         list_move(&req->list, &to_end);
2155                                 }
2156                                 spin_unlock(&req->waitq.lock);
2157                         }
2158                         for (i = 0; i < FUSE_PQ_HASH_SIZE; i++)
2159                                 list_splice_tail_init(&fpq->processing[i],
2160                                                       &to_end);
2161                         spin_unlock(&fpq->lock);
2162                 }
2163                 spin_lock(&fc->bg_lock);
2164                 fc->blocked = 0;
2165                 fc->max_background = UINT_MAX;
2166                 flush_bg_queue(fc);
2167                 spin_unlock(&fc->bg_lock);
2168
2169                 spin_lock(&fiq->lock);
2170                 fiq->connected = 0;
2171                 list_for_each_entry(req, &fiq->pending, list)
2172                         clear_bit(FR_PENDING, &req->flags);
2173                 list_splice_tail_init(&fiq->pending, &to_end);
2174                 while (forget_pending(fiq))
2175                         kfree(fuse_dequeue_forget(fiq, 1, NULL));
2176                 wake_up_all(&fiq->waitq);
2177                 spin_unlock(&fiq->lock);
2178                 kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
2179                 end_polls(fc);
2180                 wake_up_all(&fc->blocked_waitq);
2181                 spin_unlock(&fc->lock);
2182
2183                 end_requests(&to_end);
2184         } else {
2185                 spin_unlock(&fc->lock);
2186         }
2187 }
2188 EXPORT_SYMBOL_GPL(fuse_abort_conn);
2189
2190 void fuse_wait_aborted(struct fuse_conn *fc)
2191 {
2192         /* matches implicit memory barrier in fuse_drop_waiting() */
2193         smp_mb();
2194         wait_event(fc->blocked_waitq, atomic_read(&fc->num_waiting) == 0);
2195 }
2196
2197 int fuse_dev_release(struct inode *inode, struct file *file)
2198 {
2199         struct fuse_dev *fud = fuse_get_dev(file);
2200
2201         if (fud) {
2202                 struct fuse_conn *fc = fud->fc;
2203                 struct fuse_pqueue *fpq = &fud->pq;
2204                 LIST_HEAD(to_end);
2205                 unsigned int i;
2206
2207                 spin_lock(&fpq->lock);
2208                 WARN_ON(!list_empty(&fpq->io));
2209                 for (i = 0; i < FUSE_PQ_HASH_SIZE; i++)
2210                         list_splice_init(&fpq->processing[i], &to_end);
2211                 spin_unlock(&fpq->lock);
2212
2213                 end_requests(&to_end);
2214
2215                 /* Are we the last open device? */
2216                 if (atomic_dec_and_test(&fc->dev_count)) {
2217                         WARN_ON(fc->iq.fasync != NULL);
2218                         fuse_abort_conn(fc);
2219                 }
2220                 fuse_dev_free(fud);
2221         }
2222         return 0;
2223 }
2224 EXPORT_SYMBOL_GPL(fuse_dev_release);
2225
2226 static int fuse_dev_fasync(int fd, struct file *file, int on)
2227 {
2228         struct fuse_dev *fud = fuse_get_dev(file);
2229
2230         if (!fud)
2231                 return -EPERM;
2232
2233         /* No locking - fasync_helper does its own locking */
2234         return fasync_helper(fd, file, on, &fud->fc->iq.fasync);
2235 }
2236
2237 static int fuse_device_clone(struct fuse_conn *fc, struct file *new)
2238 {
2239         struct fuse_dev *fud;
2240
2241         if (new->private_data)
2242                 return -EINVAL;
2243
2244         fud = fuse_dev_alloc_install(fc);
2245         if (!fud)
2246                 return -ENOMEM;
2247
2248         new->private_data = fud;
2249         atomic_inc(&fc->dev_count);
2250
2251         return 0;
2252 }
2253
2254 static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
2255                            unsigned long arg)
2256 {
2257         int res;
2258         int oldfd;
2259         struct fuse_dev *fud = NULL;
2260         struct fd f;
2261
2262         switch (cmd) {
2263         case FUSE_DEV_IOC_CLONE:
2264                 if (get_user(oldfd, (__u32 __user *)arg))
2265                         return -EFAULT;
2266
2267                 f = fdget(oldfd);
2268                 if (!f.file)
2269                         return -EINVAL;
2270
2271                 /*
2272                  * Check against file->f_op because CUSE
2273                  * uses the same ioctl handler.
2274                  */
2275                 if (f.file->f_op == file->f_op)
2276                         fud = fuse_get_dev(f.file);
2277
2278                 res = -EINVAL;
2279                 if (fud) {
2280                         mutex_lock(&fuse_mutex);
2281                         res = fuse_device_clone(fud->fc, file);
2282                         mutex_unlock(&fuse_mutex);
2283                 }
2284                 fdput(f);
2285                 break;
2286         default:
2287                 res = -ENOTTY;
2288                 break;
2289         }
2290         return res;
2291 }
2292
2293 const struct file_operations fuse_dev_operations = {
2294         .owner          = THIS_MODULE,
2295         .open           = fuse_dev_open,
2296         .llseek         = no_llseek,
2297         .read_iter      = fuse_dev_read,
2298         .splice_read    = fuse_dev_splice_read,
2299         .write_iter     = fuse_dev_write,
2300         .splice_write   = fuse_dev_splice_write,
2301         .poll           = fuse_dev_poll,
2302         .release        = fuse_dev_release,
2303         .fasync         = fuse_dev_fasync,
2304         .unlocked_ioctl = fuse_dev_ioctl,
2305         .compat_ioctl   = compat_ptr_ioctl,
2306 };
2307 EXPORT_SYMBOL_GPL(fuse_dev_operations);
2308
2309 static struct miscdevice fuse_miscdevice = {
2310         .minor = FUSE_MINOR,
2311         .name  = "fuse",
2312         .fops = &fuse_dev_operations,
2313 };
2314
2315 int __init fuse_dev_init(void)
2316 {
2317         int err = -ENOMEM;
2318         fuse_req_cachep = kmem_cache_create("fuse_request",
2319                                             sizeof(struct fuse_req),
2320                                             0, 0, NULL);
2321         if (!fuse_req_cachep)
2322                 goto out;
2323
2324         err = misc_register(&fuse_miscdevice);
2325         if (err)
2326                 goto out_cache_clean;
2327
2328         return 0;
2329
2330  out_cache_clean:
2331         kmem_cache_destroy(fuse_req_cachep);
2332  out:
2333         return err;
2334 }
2335
2336 void fuse_dev_cleanup(void)
2337 {
2338         misc_deregister(&fuse_miscdevice);
2339         kmem_cache_destroy(fuse_req_cachep);
2340 }