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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/sched/signal.h>
 15 #include <linux/uio.h>
 16 #include <linux/miscdevice.h>
 17 #include <linux/pagemap.h>
 18 #include <linux/file.h>
 19 #include <linux/slab.h>
 20 #include <linux/pipe_fs_i.h>
 21 #include <linux/swap.h>
 22 #include <linux/splice.h>
 23 #include <linux/sched.h>
 24 
 25 MODULE_ALIAS_MISCDEV(FUSE_MINOR);
 26 MODULE_ALIAS("devname:fuse");
 27 
 28 /* Ordinary requests have even IDs, while interrupts IDs are odd */
 29 #define FUSE_INT_REQ_BIT (1ULL << 0)
 30 #define FUSE_REQ_ID_STEP (1ULL << 1)
 31 
 32 static struct kmem_cache *fuse_req_cachep;
 33 
 34 static struct fuse_dev *fuse_get_dev(struct file *file)
 35 {
 36         /*
 37          * Lockless access is OK, because file->private data is set
 38          * once during mount and is valid until the file is released.
 39          */
 40         return READ_ONCE(file->private_data);
 41 }
 42 
 43 static void fuse_request_init(struct fuse_req *req, struct page **pages,
 44                               struct fuse_page_desc *page_descs,
 45                               unsigned npages)
 46 {
 47         INIT_LIST_HEAD(&req->list);
 48         INIT_LIST_HEAD(&req->intr_entry);
 49         init_waitqueue_head(&req->waitq);
 50         refcount_set(&req->count, 1);
 51         req->pages = pages;
 52         req->page_descs = page_descs;
 53         req->max_pages = npages;
 54         __set_bit(FR_PENDING, &req->flags);
 55 }
 56 
 57 static struct page **fuse_req_pages_alloc(unsigned int npages, gfp_t flags,
 58                                           struct fuse_page_desc **desc)
 59 {
 60         struct page **pages;
 61 
 62         pages = kzalloc(npages * (sizeof(struct page *) +
 63                                   sizeof(struct fuse_page_desc)), flags);
 64         *desc = (void *) pages + npages * sizeof(struct page *);
 65 
 66         return pages;
 67 }
 68 
 69 static struct fuse_req *__fuse_request_alloc(unsigned npages, gfp_t flags)
 70 {
 71         struct fuse_req *req = kmem_cache_zalloc(fuse_req_cachep, flags);
 72         if (req) {
 73                 struct page **pages = NULL;
 74                 struct fuse_page_desc *page_descs = NULL;
 75 
 76                 WARN_ON(npages > FUSE_MAX_MAX_PAGES);
 77                 if (npages > FUSE_REQ_INLINE_PAGES) {
 78                         pages = fuse_req_pages_alloc(npages, flags,
 79                                                      &page_descs);
 80                         if (!pages) {
 81                                 kmem_cache_free(fuse_req_cachep, req);
 82                                 return NULL;
 83                         }
 84                 } else if (npages) {
 85                         pages = req->inline_pages;
 86                         page_descs = req->inline_page_descs;
 87                 }
 88 
 89                 fuse_request_init(req, pages, page_descs, npages);
 90         }
 91         return req;
 92 }
 93 
 94 struct fuse_req *fuse_request_alloc(unsigned npages)
 95 {
 96         return __fuse_request_alloc(npages, GFP_KERNEL);
 97 }
 98 EXPORT_SYMBOL_GPL(fuse_request_alloc);
 99 
100 struct fuse_req *fuse_request_alloc_nofs(unsigned npages)
101 {
102         return __fuse_request_alloc(npages, GFP_NOFS);
103 }
104 
105 static void fuse_req_pages_free(struct fuse_req *req)
106 {
107         if (req->pages != req->inline_pages)
108                 kfree(req->pages);
109 }
110 
111 bool fuse_req_realloc_pages(struct fuse_conn *fc, struct fuse_req *req,
112                             gfp_t flags)
113 {
114         struct page **pages;
115         struct fuse_page_desc *page_descs;
116         unsigned int npages = min_t(unsigned int,
117                                     max_t(unsigned int, req->max_pages * 2,
118                                           FUSE_DEFAULT_MAX_PAGES_PER_REQ),
119                                     fc->max_pages);
120         WARN_ON(npages <= req->max_pages);
121 
122         pages = fuse_req_pages_alloc(npages, flags, &page_descs);
123         if (!pages)
124                 return false;
125 
126         memcpy(pages, req->pages, sizeof(struct page *) * req->max_pages);
127         memcpy(page_descs, req->page_descs,
128                sizeof(struct fuse_page_desc) * req->max_pages);
129         fuse_req_pages_free(req);
130         req->pages = pages;
131         req->page_descs = page_descs;
132         req->max_pages = npages;
133 
134         return true;
135 }
136 
137 void fuse_request_free(struct fuse_req *req)
138 {
139         fuse_req_pages_free(req);
140         kmem_cache_free(fuse_req_cachep, req);
141 }
142 
143 void __fuse_get_request(struct fuse_req *req)
144 {
145         refcount_inc(&req->count);
146 }
147 
148 /* Must be called with > 1 refcount */
149 static void __fuse_put_request(struct fuse_req *req)
150 {
151         refcount_dec(&req->count);
152 }
153 
154 void fuse_set_initialized(struct fuse_conn *fc)
155 {
156         /* Make sure stores before this are seen on another CPU */
157         smp_wmb();
158         fc->initialized = 1;
159 }
160 
161 static bool fuse_block_alloc(struct fuse_conn *fc, bool for_background)
162 {
163         return !fc->initialized || (for_background && fc->blocked);
164 }
165 
166 static void fuse_drop_waiting(struct fuse_conn *fc)
167 {
168         /*
169          * lockess check of fc->connected is okay, because atomic_dec_and_test()
170          * provides a memory barrier mached with the one in fuse_wait_aborted()
171          * to ensure no wake-up is missed.
172          */
173         if (atomic_dec_and_test(&fc->num_waiting) &&
174             !READ_ONCE(fc->connected)) {
175                 /* wake up aborters */
176                 wake_up_all(&fc->blocked_waitq);
177         }
178 }
179 
180 static struct fuse_req *__fuse_get_req(struct fuse_conn *fc, unsigned npages,
181                                        bool for_background)
182 {
183         struct fuse_req *req;
184         int err;
185         atomic_inc(&fc->num_waiting);
186 
187         if (fuse_block_alloc(fc, for_background)) {
188                 err = -EINTR;
189                 if (wait_event_killable_exclusive(fc->blocked_waitq,
190                                 !fuse_block_alloc(fc, for_background)))
191                         goto out;
192         }
193         /* Matches smp_wmb() in fuse_set_initialized() */
194         smp_rmb();
195 
196         err = -ENOTCONN;
197         if (!fc->connected)
198                 goto out;
199 
200         err = -ECONNREFUSED;
201         if (fc->conn_error)
202                 goto out;
203 
204         req = fuse_request_alloc(npages);
205         err = -ENOMEM;
206         if (!req) {
207                 if (for_background)
208                         wake_up(&fc->blocked_waitq);
209                 goto out;
210         }
211 
212         req->in.h.uid = from_kuid(fc->user_ns, current_fsuid());
213         req->in.h.gid = from_kgid(fc->user_ns, current_fsgid());
214         req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns);
215 
216         __set_bit(FR_WAITING, &req->flags);
217         if (for_background)
218                 __set_bit(FR_BACKGROUND, &req->flags);
219 
220         if (unlikely(req->in.h.uid == ((uid_t)-1) ||
221                      req->in.h.gid == ((gid_t)-1))) {
222                 fuse_put_request(fc, req);
223                 return ERR_PTR(-EOVERFLOW);
224         }
225         return req;
226 
227  out:
228         fuse_drop_waiting(fc);
229         return ERR_PTR(err);
230 }
231 
232 struct fuse_req *fuse_get_req(struct fuse_conn *fc, unsigned npages)
233 {
234         return __fuse_get_req(fc, npages, false);
235 }
236 EXPORT_SYMBOL_GPL(fuse_get_req);
237 
238 struct fuse_req *fuse_get_req_for_background(struct fuse_conn *fc,
239                                              unsigned npages)
240 {
241         return __fuse_get_req(fc, npages, true);
242 }
243 EXPORT_SYMBOL_GPL(fuse_get_req_for_background);
244 
245 /*
246  * Return request in fuse_file->reserved_req.  However that may
247  * currently be in use.  If that is the case, wait for it to become
248  * available.
249  */
250 static struct fuse_req *get_reserved_req(struct fuse_conn *fc,
251                                          struct file *file)
252 {
253         struct fuse_req *req = NULL;
254         struct fuse_inode *fi = get_fuse_inode(file_inode(file));
255         struct fuse_file *ff = file->private_data;
256 
257         do {
258                 wait_event(fc->reserved_req_waitq, ff->reserved_req);
259                 spin_lock(&fi->lock);
260                 if (ff->reserved_req) {
261                         req = ff->reserved_req;
262                         ff->reserved_req = NULL;
263                         req->stolen_file = get_file(file);
264                 }
265                 spin_unlock(&fi->lock);
266         } while (!req);
267 
268         return req;
269 }
270 
271 /*
272  * Put stolen request back into fuse_file->reserved_req
273  */
274 static void put_reserved_req(struct fuse_conn *fc, struct fuse_req *req)
275 {
276         struct file *file = req->stolen_file;
277         struct fuse_inode *fi = get_fuse_inode(file_inode(file));
278         struct fuse_file *ff = file->private_data;
279 
280         WARN_ON(req->max_pages);
281         spin_lock(&fi->lock);
282         memset(req, 0, sizeof(*req));
283         fuse_request_init(req, NULL, NULL, 0);
284         BUG_ON(ff->reserved_req);
285         ff->reserved_req = req;
286         wake_up_all(&fc->reserved_req_waitq);
287         spin_unlock(&fi->lock);
288         fput(file);
289 }
290 
291 /*
292  * Gets a requests for a file operation, always succeeds
293  *
294  * This is used for sending the FLUSH request, which must get to
295  * userspace, due to POSIX locks which may need to be unlocked.
296  *
297  * If allocation fails due to OOM, use the reserved request in
298  * fuse_file.
299  *
300  * This is very unlikely to deadlock accidentally, since the
301  * filesystem should not have it's own file open.  If deadlock is
302  * intentional, it can still be broken by "aborting" the filesystem.
303  */
304 struct fuse_req *fuse_get_req_nofail_nopages(struct fuse_conn *fc,
305                                              struct file *file)
306 {
307         struct fuse_req *req;
308 
309         atomic_inc(&fc->num_waiting);
310         wait_event(fc->blocked_waitq, fc->initialized);
311         /* Matches smp_wmb() in fuse_set_initialized() */
312         smp_rmb();
313         req = fuse_request_alloc(0);
314         if (!req)
315                 req = get_reserved_req(fc, file);
316 
317         req->in.h.uid = from_kuid_munged(fc->user_ns, current_fsuid());
318         req->in.h.gid = from_kgid_munged(fc->user_ns, current_fsgid());
319         req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns);
320 
321         __set_bit(FR_WAITING, &req->flags);
322         __clear_bit(FR_BACKGROUND, &req->flags);
323         return req;
324 }
325 
326 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
327 {
328         if (refcount_dec_and_test(&req->count)) {
329                 if (test_bit(FR_BACKGROUND, &req->flags)) {
330                         /*
331                          * We get here in the unlikely case that a background
332                          * request was allocated but not sent
333                          */
334                         spin_lock(&fc->bg_lock);
335                         if (!fc->blocked)
336                                 wake_up(&fc->blocked_waitq);
337                         spin_unlock(&fc->bg_lock);
338                 }
339 
340                 if (test_bit(FR_WAITING, &req->flags)) {
341                         __clear_bit(FR_WAITING, &req->flags);
342                         fuse_drop_waiting(fc);
343                 }
344 
345                 if (req->stolen_file)
346                         put_reserved_req(fc, req);
347                 else
348                         fuse_request_free(req);
349         }
350 }
351 EXPORT_SYMBOL_GPL(fuse_put_request);
352 
353 static unsigned len_args(unsigned numargs, struct fuse_arg *args)
354 {
355         unsigned nbytes = 0;
356         unsigned i;
357 
358         for (i = 0; i < numargs; i++)
359                 nbytes += args[i].size;
360 
361         return nbytes;
362 }
363 
364 static u64 fuse_get_unique(struct fuse_iqueue *fiq)
365 {
366         fiq->reqctr += FUSE_REQ_ID_STEP;
367         return fiq->reqctr;
368 }
369 
370 static unsigned int fuse_req_hash(u64 unique)
371 {
372         return hash_long(unique & ~FUSE_INT_REQ_BIT, FUSE_PQ_HASH_BITS);
373 }
374 
375 static void queue_request(struct fuse_iqueue *fiq, struct fuse_req *req)
376 {
377         req->in.h.len = sizeof(struct fuse_in_header) +
378                 len_args(req->in.numargs, (struct fuse_arg *) req->in.args);
379         list_add_tail(&req->list, &fiq->pending);
380         wake_up(&fiq->waitq);
381         kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
382 }
383 
384 void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
385                        u64 nodeid, u64 nlookup)
386 {
387         struct fuse_iqueue *fiq = &fc->iq;
388 
389         forget->forget_one.nodeid = nodeid;
390         forget->forget_one.nlookup = nlookup;
391 
392         spin_lock(&fiq->lock);
393         if (fiq->connected) {
394                 fiq->forget_list_tail->next = forget;
395                 fiq->forget_list_tail = forget;
396                 wake_up(&fiq->waitq);
397                 kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
398         } else {
399                 kfree(forget);
400         }
401         spin_unlock(&fiq->lock);
402 }
403 
404 static void flush_bg_queue(struct fuse_conn *fc)
405 {
406         struct fuse_iqueue *fiq = &fc->iq;
407 
408         while (fc->active_background < fc->max_background &&
409                !list_empty(&fc->bg_queue)) {
410                 struct fuse_req *req;
411 
412                 req = list_first_entry(&fc->bg_queue, struct fuse_req, list);
413                 list_del(&req->list);
414                 fc->active_background++;
415                 spin_lock(&fiq->lock);
416                 req->in.h.unique = fuse_get_unique(fiq);
417                 queue_request(fiq, req);
418                 spin_unlock(&fiq->lock);
419         }
420 }
421 
422 /*
423  * This function is called when a request is finished.  Either a reply
424  * has arrived or it was aborted (and not yet sent) or some error
425  * occurred during communication with userspace, or the device file
426  * was closed.  The requester thread is woken up (if still waiting),
427  * the 'end' callback is called if given, else the reference to the
428  * request is released
429  */
430 static void request_end(struct fuse_conn *fc, struct fuse_req *req)
431 {
432         struct fuse_iqueue *fiq = &fc->iq;
433 
434         if (test_and_set_bit(FR_FINISHED, &req->flags))
435                 goto put_request;
436         /*
437          * test_and_set_bit() implies smp_mb() between bit
438          * changing and below intr_entry check. Pairs with
439          * smp_mb() from queue_interrupt().
440          */
441         if (!list_empty(&req->intr_entry)) {
442                 spin_lock(&fiq->lock);
443                 list_del_init(&req->intr_entry);
444                 spin_unlock(&fiq->lock);
445         }
446         WARN_ON(test_bit(FR_PENDING, &req->flags));
447         WARN_ON(test_bit(FR_SENT, &req->flags));
448         if (test_bit(FR_BACKGROUND, &req->flags)) {
449                 spin_lock(&fc->bg_lock);
450                 clear_bit(FR_BACKGROUND, &req->flags);
451                 if (fc->num_background == fc->max_background) {
452                         fc->blocked = 0;
453                         wake_up(&fc->blocked_waitq);
454                 } else if (!fc->blocked) {
455                         /*
456                          * Wake up next waiter, if any.  It's okay to use
457                          * waitqueue_active(), as we've already synced up
458                          * fc->blocked with waiters with the wake_up() call
459                          * above.
460                          */
461                         if (waitqueue_active(&fc->blocked_waitq))
462                                 wake_up(&fc->blocked_waitq);
463                 }
464 
465                 if (fc->num_background == fc->congestion_threshold && fc->sb) {
466                         clear_bdi_congested(fc->sb->s_bdi, BLK_RW_SYNC);
467                         clear_bdi_congested(fc->sb->s_bdi, BLK_RW_ASYNC);
468                 }
469                 fc->num_background--;
470                 fc->active_background--;
471                 flush_bg_queue(fc);
472                 spin_unlock(&fc->bg_lock);
473         } else {
474                 /* Wake up waiter sleeping in request_wait_answer() */
475                 wake_up(&req->waitq);
476         }
477 
478         if (req->end)
479                 req->end(fc, req);
480 put_request:
481         fuse_put_request(fc, req);
482 }
483 
484 static int queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req)
485 {
486         spin_lock(&fiq->lock);
487         /* Check for we've sent request to interrupt this req */
488         if (unlikely(!test_bit(FR_INTERRUPTED, &req->flags))) {
489                 spin_unlock(&fiq->lock);
490                 return -EINVAL;
491         }
492 
493         if (list_empty(&req->intr_entry)) {
494                 list_add_tail(&req->intr_entry, &fiq->interrupts);
495                 /*
496                  * Pairs with smp_mb() implied by test_and_set_bit()
497                  * from request_end().
498                  */
499                 smp_mb();
500                 if (test_bit(FR_FINISHED, &req->flags)) {
501                         list_del_init(&req->intr_entry);
502                         spin_unlock(&fiq->lock);
503                         return 0;
504                 }
505                 wake_up(&fiq->waitq);
506                 kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
507         }
508         spin_unlock(&fiq->lock);
509         return 0;
510 }
511 
512 static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
513 {
514         struct fuse_iqueue *fiq = &fc->iq;
515         int err;
516 
517         if (!fc->no_interrupt) {
518                 /* Any signal may interrupt this */
519                 err = wait_event_interruptible(req->waitq,
520                                         test_bit(FR_FINISHED, &req->flags));
521                 if (!err)
522                         return;
523 
524                 set_bit(FR_INTERRUPTED, &req->flags);
525                 /* matches barrier in fuse_dev_do_read() */
526                 smp_mb__after_atomic();
527                 if (test_bit(FR_SENT, &req->flags))
528                         queue_interrupt(fiq, req);
529         }
530 
531         if (!test_bit(FR_FORCE, &req->flags)) {
532                 /* Only fatal signals may interrupt this */
533                 err = wait_event_killable(req->waitq,
534                                         test_bit(FR_FINISHED, &req->flags));
535                 if (!err)
536                         return;
537 
538                 spin_lock(&fiq->lock);
539                 /* Request is not yet in userspace, bail out */
540                 if (test_bit(FR_PENDING, &req->flags)) {
541                         list_del(&req->list);
542                         spin_unlock(&fiq->lock);
543                         __fuse_put_request(req);
544                         req->out.h.error = -EINTR;
545                         return;
546                 }
547                 spin_unlock(&fiq->lock);
548         }
549 
550         /*
551          * Either request is already in userspace, or it was forced.
552          * Wait it out.
553          */
554         wait_event(req->waitq, test_bit(FR_FINISHED, &req->flags));
555 }
556 
557 static void __fuse_request_send(struct fuse_conn *fc, struct fuse_req *req)
558 {
559         struct fuse_iqueue *fiq = &fc->iq;
560 
561         BUG_ON(test_bit(FR_BACKGROUND, &req->flags));
562         spin_lock(&fiq->lock);
563         if (!fiq->connected) {
564                 spin_unlock(&fiq->lock);
565                 req->out.h.error = -ENOTCONN;
566         } else {
567                 req->in.h.unique = fuse_get_unique(fiq);
568                 queue_request(fiq, req);
569                 /* acquire extra reference, since request is still needed
570                    after request_end() */
571                 __fuse_get_request(req);
572                 spin_unlock(&fiq->lock);
573 
574                 request_wait_answer(fc, req);
575                 /* Pairs with smp_wmb() in request_end() */
576                 smp_rmb();
577         }
578 }
579 
580 void fuse_request_send(struct fuse_conn *fc, struct fuse_req *req)
581 {
582         __set_bit(FR_ISREPLY, &req->flags);
583         if (!test_bit(FR_WAITING, &req->flags)) {
584                 __set_bit(FR_WAITING, &req->flags);
585                 atomic_inc(&fc->num_waiting);
586         }
587         __fuse_request_send(fc, req);
588 }
589 EXPORT_SYMBOL_GPL(fuse_request_send);
590 
591 static void fuse_adjust_compat(struct fuse_conn *fc, struct fuse_args *args)
592 {
593         if (fc->minor < 4 && args->in.h.opcode == FUSE_STATFS)
594                 args->out.args[0].size = FUSE_COMPAT_STATFS_SIZE;
595 
596         if (fc->minor < 9) {
597                 switch (args->in.h.opcode) {
598                 case FUSE_LOOKUP:
599                 case FUSE_CREATE:
600                 case FUSE_MKNOD:
601                 case FUSE_MKDIR:
602                 case FUSE_SYMLINK:
603                 case FUSE_LINK:
604                         args->out.args[0].size = FUSE_COMPAT_ENTRY_OUT_SIZE;
605                         break;
606                 case FUSE_GETATTR:
607                 case FUSE_SETATTR:
608                         args->out.args[0].size = FUSE_COMPAT_ATTR_OUT_SIZE;
609                         break;
610                 }
611         }
612         if (fc->minor < 12) {
613                 switch (args->in.h.opcode) {
614                 case FUSE_CREATE:
615                         args->in.args[0].size = sizeof(struct fuse_open_in);
616                         break;
617                 case FUSE_MKNOD:
618                         args->in.args[0].size = FUSE_COMPAT_MKNOD_IN_SIZE;
619                         break;
620                 }
621         }
622 }
623 
624 ssize_t fuse_simple_request(struct fuse_conn *fc, struct fuse_args *args)
625 {
626         struct fuse_req *req;
627         ssize_t ret;
628 
629         req = fuse_get_req(fc, 0);
630         if (IS_ERR(req))
631                 return PTR_ERR(req);
632 
633         /* Needs to be done after fuse_get_req() so that fc->minor is valid */
634         fuse_adjust_compat(fc, args);
635 
636         req->in.h.opcode = args->in.h.opcode;
637         req->in.h.nodeid = args->in.h.nodeid;
638         req->in.numargs = args->in.numargs;
639         memcpy(req->in.args, args->in.args,
640                args->in.numargs * sizeof(struct fuse_in_arg));
641         req->out.argvar = args->out.argvar;
642         req->out.numargs = args->out.numargs;
643         memcpy(req->out.args, args->out.args,
644                args->out.numargs * sizeof(struct fuse_arg));
645         fuse_request_send(fc, req);
646         ret = req->out.h.error;
647         if (!ret && args->out.argvar) {
648                 BUG_ON(args->out.numargs != 1);
649                 ret = req->out.args[0].size;
650         }
651         fuse_put_request(fc, req);
652 
653         return ret;
654 }
655 
656 bool fuse_request_queue_background(struct fuse_conn *fc, struct fuse_req *req)
657 {
658         bool queued = false;
659 
660         WARN_ON(!test_bit(FR_BACKGROUND, &req->flags));
661         if (!test_bit(FR_WAITING, &req->flags)) {
662                 __set_bit(FR_WAITING, &req->flags);
663                 atomic_inc(&fc->num_waiting);
664         }
665         __set_bit(FR_ISREPLY, &req->flags);
666         spin_lock(&fc->bg_lock);
667         if (likely(fc->connected)) {
668                 fc->num_background++;
669                 if (fc->num_background == fc->max_background)
670                         fc->blocked = 1;
671                 if (fc->num_background == fc->congestion_threshold && fc->sb) {
672                         set_bdi_congested(fc->sb->s_bdi, BLK_RW_SYNC);
673                         set_bdi_congested(fc->sb->s_bdi, BLK_RW_ASYNC);
674                 }
675                 list_add_tail(&req->list, &fc->bg_queue);
676                 flush_bg_queue(fc);
677                 queued = true;
678         }
679         spin_unlock(&fc->bg_lock);
680 
681         return queued;
682 }
683 
684 void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req)
685 {
686         WARN_ON(!req->end);
687         if (!fuse_request_queue_background(fc, req)) {
688                 req->out.h.error = -ENOTCONN;
689                 req->end(fc, req);
690                 fuse_put_request(fc, req);
691         }
692 }
693 EXPORT_SYMBOL_GPL(fuse_request_send_background);
694 
695 static int fuse_request_send_notify_reply(struct fuse_conn *fc,
696                                           struct fuse_req *req, u64 unique)
697 {
698         int err = -ENODEV;
699         struct fuse_iqueue *fiq = &fc->iq;
700 
701         __clear_bit(FR_ISREPLY, &req->flags);
702         req->in.h.unique = unique;
703         spin_lock(&fiq->lock);
704         if (fiq->connected) {
705                 queue_request(fiq, req);
706                 err = 0;
707         }
708         spin_unlock(&fiq->lock);
709 
710         return err;
711 }
712 
713 void fuse_force_forget(struct file *file, u64 nodeid)
714 {
715         struct inode *inode = file_inode(file);
716         struct fuse_conn *fc = get_fuse_conn(inode);
717         struct fuse_req *req;
718         struct fuse_forget_in inarg;
719 
720         memset(&inarg, 0, sizeof(inarg));
721         inarg.nlookup = 1;
722         req = fuse_get_req_nofail_nopages(fc, file);
723         req->in.h.opcode = FUSE_FORGET;
724         req->in.h.nodeid = nodeid;
725         req->in.numargs = 1;
726         req->in.args[0].size = sizeof(inarg);
727         req->in.args[0].value = &inarg;
728         __clear_bit(FR_ISREPLY, &req->flags);
729         __fuse_request_send(fc, req);
730         /* ignore errors */
731         fuse_put_request(fc, req);
732 }
733 
734 /*
735  * Lock the request.  Up to the next unlock_request() there mustn't be
736  * anything that could cause a page-fault.  If the request was already
737  * aborted bail out.
738  */
739 static int lock_request(struct fuse_req *req)
740 {
741         int err = 0;
742         if (req) {
743                 spin_lock(&req->waitq.lock);
744                 if (test_bit(FR_ABORTED, &req->flags))
745                         err = -ENOENT;
746                 else
747                         set_bit(FR_LOCKED, &req->flags);
748                 spin_unlock(&req->waitq.lock);
749         }
750         return err;
751 }
752 
753 /*
754  * Unlock request.  If it was aborted while locked, caller is responsible
755  * for unlocking and ending the request.
756  */
757 static int unlock_request(struct fuse_req *req)
758 {
759         int err = 0;
760         if (req) {
761                 spin_lock(&req->waitq.lock);
762                 if (test_bit(FR_ABORTED, &req->flags))
763                         err = -ENOENT;
764                 else
765                         clear_bit(FR_LOCKED, &req->flags);
766                 spin_unlock(&req->waitq.lock);
767         }
768         return err;
769 }
770 
771 struct fuse_copy_state {
772         int write;
773         struct fuse_req *req;
774         struct iov_iter *iter;
775         struct pipe_buffer *pipebufs;
776         struct pipe_buffer *currbuf;
777         struct pipe_inode_info *pipe;
778         unsigned long nr_segs;
779         struct page *pg;
780         unsigned len;
781         unsigned offset;
782         unsigned move_pages:1;
783 };
784 
785 static void fuse_copy_init(struct fuse_copy_state *cs, int write,
786                            struct iov_iter *iter)
787 {
788         memset(cs, 0, sizeof(*cs));
789         cs->write = write;
790         cs->iter = iter;
791 }
792 
793 /* Unmap and put previous page of userspace buffer */
794 static void fuse_copy_finish(struct fuse_copy_state *cs)
795 {
796         if (cs->currbuf) {
797                 struct pipe_buffer *buf = cs->currbuf;
798 
799                 if (cs->write)
800                         buf->len = PAGE_SIZE - cs->len;
801                 cs->currbuf = NULL;
802         } else if (cs->pg) {
803                 if (cs->write) {
804                         flush_dcache_page(cs->pg);
805                         set_page_dirty_lock(cs->pg);
806                 }
807                 put_page(cs->pg);
808         }
809         cs->pg = NULL;
810 }
811 
812 /*
813  * Get another pagefull of userspace buffer, and map it to kernel
814  * address space, and lock request
815  */
816 static int fuse_copy_fill(struct fuse_copy_state *cs)
817 {
818         struct page *page;
819         int err;
820 
821         err = unlock_request(cs->req);
822         if (err)
823                 return err;
824 
825         fuse_copy_finish(cs);
826         if (cs->pipebufs) {
827                 struct pipe_buffer *buf = cs->pipebufs;
828 
829                 if (!cs->write) {
830                         err = pipe_buf_confirm(cs->pipe, buf);
831                         if (err)
832                                 return err;
833 
834                         BUG_ON(!cs->nr_segs);
835                         cs->currbuf = buf;
836                         cs->pg = buf->page;
837                         cs->offset = buf->offset;
838                         cs->len = buf->len;
839                         cs->pipebufs++;
840                         cs->nr_segs--;
841                 } else {
842                         if (cs->nr_segs == cs->pipe->buffers)
843                                 return -EIO;
844 
845                         page = alloc_page(GFP_HIGHUSER);
846                         if (!page)
847                                 return -ENOMEM;
848 
849                         buf->page = page;
850                         buf->offset = 0;
851                         buf->len = 0;
852 
853                         cs->currbuf = buf;
854                         cs->pg = page;
855                         cs->offset = 0;
856                         cs->len = PAGE_SIZE;
857                         cs->pipebufs++;
858                         cs->nr_segs++;
859                 }
860         } else {
861                 size_t off;
862                 err = iov_iter_get_pages(cs->iter, &page, PAGE_SIZE, 1, &off);
863                 if (err < 0)
864                         return err;
865                 BUG_ON(!err);
866                 cs->len = err;
867                 cs->offset = off;
868                 cs->pg = page;
869                 iov_iter_advance(cs->iter, err);
870         }
871 
872         return lock_request(cs->req);
873 }
874 
875 /* Do as much copy to/from userspace buffer as we can */
876 static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
877 {
878         unsigned ncpy = min(*size, cs->len);
879         if (val) {
880                 void *pgaddr = kmap_atomic(cs->pg);
881                 void *buf = pgaddr + cs->offset;
882 
883                 if (cs->write)
884                         memcpy(buf, *val, ncpy);
885                 else
886                         memcpy(*val, buf, ncpy);
887 
888                 kunmap_atomic(pgaddr);
889                 *val += ncpy;
890         }
891         *size -= ncpy;
892         cs->len -= ncpy;
893         cs->offset += ncpy;
894         return ncpy;
895 }
896 
897 static int fuse_check_page(struct page *page)
898 {
899         if (page_mapcount(page) ||
900             page->mapping != NULL ||
901             page_count(page) != 1 ||
902             (page->flags & PAGE_FLAGS_CHECK_AT_PREP &
903              ~(1 << PG_locked |
904                1 << PG_referenced |
905                1 << PG_uptodate |
906                1 << PG_lru |
907                1 << PG_active |
908                1 << PG_reclaim))) {
909                 pr_warn("trying to steal weird page\n");
910                 pr_warn("  page=%p index=%li flags=%08lx, count=%i, mapcount=%i, mapping=%p\n", page, page->index, page->flags, page_count(page), page_mapcount(page), page->mapping);
911                 return 1;
912         }
913         return 0;
914 }
915 
916 static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
917 {
918         int err;
919         struct page *oldpage = *pagep;
920         struct page *newpage;
921         struct pipe_buffer *buf = cs->pipebufs;
922 
923         err = unlock_request(cs->req);
924         if (err)
925                 return err;
926 
927         fuse_copy_finish(cs);
928 
929         err = pipe_buf_confirm(cs->pipe, buf);
930         if (err)
931                 return err;
932 
933         BUG_ON(!cs->nr_segs);
934         cs->currbuf = buf;
935         cs->len = buf->len;
936         cs->pipebufs++;
937         cs->nr_segs--;
938 
939         if (cs->len != PAGE_SIZE)
940                 goto out_fallback;
941 
942         if (pipe_buf_steal(cs->pipe, buf) != 0)
943                 goto out_fallback;
944 
945         newpage = buf->page;
946 
947         if (!PageUptodate(newpage))
948                 SetPageUptodate(newpage);
949 
950         ClearPageMappedToDisk(newpage);
951 
952         if (fuse_check_page(newpage) != 0)
953                 goto out_fallback_unlock;
954 
955         /*
956          * This is a new and locked page, it shouldn't be mapped or
957          * have any special flags on it
958          */
959         if (WARN_ON(page_mapped(oldpage)))
960                 goto out_fallback_unlock;
961         if (WARN_ON(page_has_private(oldpage)))
962                 goto out_fallback_unlock;
963         if (WARN_ON(PageDirty(oldpage) || PageWriteback(oldpage)))
964                 goto out_fallback_unlock;
965         if (WARN_ON(PageMlocked(oldpage)))
966                 goto out_fallback_unlock;
967 
968         err = replace_page_cache_page(oldpage, newpage, GFP_KERNEL);
969         if (err) {
970                 unlock_page(newpage);
971                 return err;
972         }
973 
974         get_page(newpage);
975 
976         if (!(buf->flags & PIPE_BUF_FLAG_LRU))
977                 lru_cache_add_file(newpage);
978 
979         err = 0;
980         spin_lock(&cs->req->waitq.lock);
981         if (test_bit(FR_ABORTED, &cs->req->flags))
982                 err = -ENOENT;
983         else
984                 *pagep = newpage;
985         spin_unlock(&cs->req->waitq.lock);
986 
987         if (err) {
988                 unlock_page(newpage);
989                 put_page(newpage);
990                 return err;
991         }
992 
993         unlock_page(oldpage);
994         put_page(oldpage);
995         cs->len = 0;
996 
997         return 0;
998 
999 out_fallback_unlock:
1000         unlock_page(newpage);
1001 out_fallback:
1002         cs->pg = buf->page;
1003         cs->offset = buf->offset;
1004 
1005         err = lock_request(cs->req);
1006         if (err)
1007                 return err;
1008 
1009         return 1;
1010 }
1011 
1012 static int fuse_ref_page(struct fuse_copy_state *cs, struct page *page,
1013                          unsigned offset, unsigned count)
1014 {
1015         struct pipe_buffer *buf;
1016         int err;
1017 
1018         if (cs->nr_segs == cs->pipe->buffers)
1019                 return -EIO;
1020 
1021         err = unlock_request(cs->req);
1022         if (err)
1023                 return err;
1024 
1025         fuse_copy_finish(cs);
1026 
1027         buf = cs->pipebufs;
1028         get_page(page);
1029         buf->page = page;
1030         buf->offset = offset;
1031         buf->len = count;
1032 
1033         cs->pipebufs++;
1034         cs->nr_segs++;
1035         cs->len = 0;
1036 
1037         return 0;
1038 }
1039 
1040 /*
1041  * Copy a page in the request to/from the userspace buffer.  Must be
1042  * done atomically
1043  */
1044 static int fuse_copy_page(struct fuse_copy_state *cs, struct page **pagep,
1045                           unsigned offset, unsigned count, int zeroing)
1046 {
1047         int err;
1048         struct page *page = *pagep;
1049 
1050         if (page && zeroing && count < PAGE_SIZE)
1051                 clear_highpage(page);
1052 
1053         while (count) {
1054                 if (cs->write && cs->pipebufs && page) {
1055                         return fuse_ref_page(cs, page, offset, count);
1056                 } else if (!cs->len) {
1057                         if (cs->move_pages && page &&
1058                             offset == 0 && count == PAGE_SIZE) {
1059                                 err = fuse_try_move_page(cs, pagep);
1060                                 if (err <= 0)
1061                                         return err;
1062                         } else {
1063                                 err = fuse_copy_fill(cs);
1064                                 if (err)
1065                                         return err;
1066                         }
1067                 }
1068                 if (page) {
1069                         void *mapaddr = kmap_atomic(page);
1070                         void *buf = mapaddr + offset;
1071                         offset += fuse_copy_do(cs, &buf, &count);
1072                         kunmap_atomic(mapaddr);
1073                 } else
1074                         offset += fuse_copy_do(cs, NULL, &count);
1075         }
1076         if (page && !cs->write)
1077                 flush_dcache_page(page);
1078         return 0;
1079 }
1080 
1081 /* Copy pages in the request to/from userspace buffer */
1082 static int fuse_copy_pages(struct fuse_copy_state *cs, unsigned nbytes,
1083                            int zeroing)
1084 {
1085         unsigned i;
1086         struct fuse_req *req = cs->req;
1087 
1088         for (i = 0; i < req->num_pages && (nbytes || zeroing); i++) {
1089                 int err;
1090                 unsigned offset = req->page_descs[i].offset;
1091                 unsigned count = min(nbytes, req->page_descs[i].length);
1092 
1093                 err = fuse_copy_page(cs, &req->pages[i], offset, count,
1094                                      zeroing);
1095                 if (err)
1096                         return err;
1097 
1098                 nbytes -= count;
1099         }
1100         return 0;
1101 }
1102 
1103 /* Copy a single argument in the request to/from userspace buffer */
1104 static int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned size)
1105 {
1106         while (size) {
1107                 if (!cs->len) {
1108                         int err = fuse_copy_fill(cs);
1109                         if (err)
1110                                 return err;
1111                 }
1112                 fuse_copy_do(cs, &val, &size);
1113         }
1114         return 0;
1115 }
1116 
1117 /* Copy request arguments to/from userspace buffer */
1118 static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs,
1119                           unsigned argpages, struct fuse_arg *args,
1120                           int zeroing)
1121 {
1122         int err = 0;
1123         unsigned i;
1124 
1125         for (i = 0; !err && i < numargs; i++)  {
1126                 struct fuse_arg *arg = &args[i];
1127                 if (i == numargs - 1 && argpages)
1128                         err = fuse_copy_pages(cs, arg->size, zeroing);
1129                 else
1130                         err = fuse_copy_one(cs, arg->value, arg->size);
1131         }
1132         return err;
1133 }
1134 
1135 static int forget_pending(struct fuse_iqueue *fiq)
1136 {
1137         return fiq->forget_list_head.next != NULL;
1138 }
1139 
1140 static int request_pending(struct fuse_iqueue *fiq)
1141 {
1142         return !list_empty(&fiq->pending) || !list_empty(&fiq->interrupts) ||
1143                 forget_pending(fiq);
1144 }
1145 
1146 /*
1147  * Transfer an interrupt request to userspace
1148  *
1149  * Unlike other requests this is assembled on demand, without a need
1150  * to allocate a separate fuse_req structure.
1151  *
1152  * Called with fiq->lock held, releases it
1153  */
1154 static int fuse_read_interrupt(struct fuse_iqueue *fiq,
1155                                struct fuse_copy_state *cs,
1156                                size_t nbytes, struct fuse_req *req)
1157 __releases(fiq->lock)
1158 {
1159         struct fuse_in_header ih;
1160         struct fuse_interrupt_in arg;
1161         unsigned reqsize = sizeof(ih) + sizeof(arg);
1162         int err;
1163 
1164         list_del_init(&req->intr_entry);
1165         memset(&ih, 0, sizeof(ih));
1166         memset(&arg, 0, sizeof(arg));
1167         ih.len = reqsize;
1168         ih.opcode = FUSE_INTERRUPT;
1169         ih.unique = (req->in.h.unique | FUSE_INT_REQ_BIT);
1170         arg.unique = req->in.h.unique;
1171 
1172         spin_unlock(&fiq->lock);
1173         if (nbytes < reqsize)
1174                 return -EINVAL;
1175 
1176         err = fuse_copy_one(cs, &ih, sizeof(ih));
1177         if (!err)
1178                 err = fuse_copy_one(cs, &arg, sizeof(arg));
1179         fuse_copy_finish(cs);
1180 
1181         return err ? err : reqsize;
1182 }
1183 
1184 static struct fuse_forget_link *dequeue_forget(struct fuse_iqueue *fiq,
1185                                                unsigned max,
1186                                                unsigned *countp)
1187 {
1188         struct fuse_forget_link *head = fiq->forget_list_head.next;
1189         struct fuse_forget_link **newhead = &head;
1190         unsigned count;
1191 
1192         for (count = 0; *newhead != NULL && count < max; count++)
1193                 newhead = &(*newhead)->next;
1194 
1195         fiq->forget_list_head.next = *newhead;
1196         *newhead = NULL;
1197         if (fiq->forget_list_head.next == NULL)
1198                 fiq->forget_list_tail = &fiq->forget_list_head;
1199 
1200         if (countp != NULL)
1201                 *countp = count;
1202 
1203         return head;
1204 }
1205 
1206 static int fuse_read_single_forget(struct fuse_iqueue *fiq,
1207                                    struct fuse_copy_state *cs,
1208                                    size_t nbytes)
1209 __releases(fiq->lock)
1210 {
1211         int err;
1212         struct fuse_forget_link *forget = dequeue_forget(fiq, 1, NULL);
1213         struct fuse_forget_in arg = {
1214                 .nlookup = forget->forget_one.nlookup,
1215         };
1216         struct fuse_in_header ih = {
1217                 .opcode = FUSE_FORGET,
1218                 .nodeid = forget->forget_one.nodeid,
1219                 .unique = fuse_get_unique(fiq),
1220                 .len = sizeof(ih) + sizeof(arg),
1221         };
1222 
1223         spin_unlock(&fiq->lock);
1224         kfree(forget);
1225         if (nbytes < ih.len)
1226                 return -EINVAL;
1227 
1228         err = fuse_copy_one(cs, &ih, sizeof(ih));
1229         if (!err)
1230                 err = fuse_copy_one(cs, &arg, sizeof(arg));
1231         fuse_copy_finish(cs);
1232 
1233         if (err)
1234                 return err;
1235 
1236         return ih.len;
1237 }
1238 
1239 static int fuse_read_batch_forget(struct fuse_iqueue *fiq,
1240                                    struct fuse_copy_state *cs, size_t nbytes)
1241 __releases(fiq->lock)
1242 {
1243         int err;
1244         unsigned max_forgets;
1245         unsigned count;
1246         struct fuse_forget_link *head;
1247         struct fuse_batch_forget_in arg = { .count = 0 };
1248         struct fuse_in_header ih = {
1249                 .opcode = FUSE_BATCH_FORGET,
1250                 .unique = fuse_get_unique(fiq),
1251                 .len = sizeof(ih) + sizeof(arg),
1252         };
1253 
1254         if (nbytes < ih.len) {
1255                 spin_unlock(&fiq->lock);
1256                 return -EINVAL;
1257         }
1258 
1259         max_forgets = (nbytes - ih.len) / sizeof(struct fuse_forget_one);
1260         head = dequeue_forget(fiq, max_forgets, &count);
1261         spin_unlock(&fiq->lock);
1262 
1263         arg.count = count;
1264         ih.len += count * sizeof(struct fuse_forget_one);
1265         err = fuse_copy_one(cs, &ih, sizeof(ih));
1266         if (!err)
1267                 err = fuse_copy_one(cs, &arg, sizeof(arg));
1268 
1269         while (head) {
1270                 struct fuse_forget_link *forget = head;
1271 
1272                 if (!err) {
1273                         err = fuse_copy_one(cs, &forget->forget_one,
1274                                             sizeof(forget->forget_one));
1275                 }
1276                 head = forget->next;
1277                 kfree(forget);
1278         }
1279 
1280         fuse_copy_finish(cs);
1281 
1282         if (err)
1283                 return err;
1284 
1285         return ih.len;
1286 }
1287 
1288 static int fuse_read_forget(struct fuse_conn *fc, struct fuse_iqueue *fiq,
1289                             struct fuse_copy_state *cs,
1290                             size_t nbytes)
1291 __releases(fiq->lock)
1292 {
1293         if (fc->minor < 16 || fiq->forget_list_head.next->next == NULL)
1294                 return fuse_read_single_forget(fiq, cs, nbytes);
1295         else
1296                 return fuse_read_batch_forget(fiq, cs, nbytes);
1297 }
1298 
1299 /*
1300  * Read a single request into the userspace filesystem's buffer.  This
1301  * function waits until a request is available, then removes it from
1302  * the pending list and copies request data to userspace buffer.  If
1303  * no reply is needed (FORGET) or request has been aborted or there
1304  * was an error during the copying then it's finished by calling
1305  * request_end().  Otherwise add it to the processing list, and set
1306  * the 'sent' flag.
1307  */
1308 static ssize_t fuse_dev_do_read(struct fuse_dev *fud, struct file *file,
1309                                 struct fuse_copy_state *cs, size_t nbytes)
1310 {
1311         ssize_t err;
1312         struct fuse_conn *fc = fud->fc;
1313         struct fuse_iqueue *fiq = &fc->iq;
1314         struct fuse_pqueue *fpq = &fud->pq;
1315         struct fuse_req *req;
1316         struct fuse_in *in;
1317         unsigned reqsize;
1318         unsigned int hash;
1319 
1320  restart:
1321         for (;;) {
1322                 spin_lock(&fiq->lock);
1323                 if (!fiq->connected || request_pending(fiq))
1324                         break;
1325                 spin_unlock(&fiq->lock);
1326 
1327                 if (file->f_flags & O_NONBLOCK)
1328                         return -EAGAIN;
1329                 err = wait_event_interruptible_exclusive(fiq->waitq,
1330                                 !fiq->connected || request_pending(fiq));
1331                 if (err)
1332                         return err;
1333         }
1334 
1335         if (!fiq->connected) {
1336                 err = fc->aborted ? -ECONNABORTED : -ENODEV;
1337                 goto err_unlock;
1338         }
1339 
1340         if (!list_empty(&fiq->interrupts)) {
1341                 req = list_entry(fiq->interrupts.next, struct fuse_req,
1342                                  intr_entry);
1343                 return fuse_read_interrupt(fiq, cs, nbytes, req);
1344         }
1345 
1346         if (forget_pending(fiq)) {
1347                 if (list_empty(&fiq->pending) || fiq->forget_batch-- > 0)
1348                         return fuse_read_forget(fc, fiq, cs, nbytes);
1349 
1350                 if (fiq->forget_batch <= -8)
1351                         fiq->forget_batch = 16;
1352         }
1353 
1354         req = list_entry(fiq->pending.next, struct fuse_req, list);
1355         clear_bit(FR_PENDING, &req->flags);
1356         list_del_init(&req->list);
1357         spin_unlock(&fiq->lock);
1358 
1359         in = &req->in;
1360         reqsize = in->h.len;
1361 
1362         /* If request is too large, reply with an error and restart the read */
1363         if (nbytes < reqsize) {
1364                 req->out.h.error = -EIO;
1365                 /* SETXATTR is special, since it may contain too large data */
1366                 if (in->h.opcode == FUSE_SETXATTR)
1367                         req->out.h.error = -E2BIG;
1368                 request_end(fc, req);
1369                 goto restart;
1370         }
1371         spin_lock(&fpq->lock);
1372         list_add(&req->list, &fpq->io);
1373         spin_unlock(&fpq->lock);
1374         cs->req = req;
1375         err = fuse_copy_one(cs, &in->h, sizeof(in->h));
1376         if (!err)
1377                 err = fuse_copy_args(cs, in->numargs, in->argpages,
1378                                      (struct fuse_arg *) in->args, 0);
1379         fuse_copy_finish(cs);
1380         spin_lock(&fpq->lock);
1381         clear_bit(FR_LOCKED, &req->flags);
1382         if (!fpq->connected) {
1383                 err = fc->aborted ? -ECONNABORTED : -ENODEV;
1384                 goto out_end;
1385         }
1386         if (err) {
1387                 req->out.h.error = -EIO;
1388                 goto out_end;
1389         }
1390         if (!test_bit(FR_ISREPLY, &req->flags)) {
1391                 err = reqsize;
1392                 goto out_end;
1393         }
1394         hash = fuse_req_hash(req->in.h.unique);
1395         list_move_tail(&req->list, &fpq->processing[hash]);
1396         __fuse_get_request(req);
1397         set_bit(FR_SENT, &req->flags);
1398         spin_unlock(&fpq->lock);
1399         /* matches barrier in request_wait_answer() */
1400         smp_mb__after_atomic();
1401         if (test_bit(FR_INTERRUPTED, &req->flags))
1402                 queue_interrupt(fiq, req);
1403         fuse_put_request(fc, req);
1404 
1405         return reqsize;
1406 
1407 out_end:
1408         if (!test_bit(FR_PRIVATE, &req->flags))
1409                 list_del_init(&req->list);
1410         spin_unlock(&fpq->lock);
1411         request_end(fc, req);
1412         return err;
1413 
1414  err_unlock:
1415         spin_unlock(&fiq->lock);
1416         return err;
1417 }
1418 
1419 static int fuse_dev_open(struct inode *inode, struct file *file)
1420 {
1421         /*
1422          * The fuse device's file's private_data is used to hold
1423          * the fuse_conn(ection) when it is mounted, and is used to
1424          * keep track of whether the file has been mounted already.
1425          */
1426         file->private_data = NULL;
1427         return 0;
1428 }
1429 
1430 static ssize_t fuse_dev_read(struct kiocb *iocb, struct iov_iter *to)
1431 {
1432         struct fuse_copy_state cs;
1433         struct file *file = iocb->ki_filp;
1434         struct fuse_dev *fud = fuse_get_dev(file);
1435 
1436         if (!fud)
1437                 return -EPERM;
1438 
1439         if (!iter_is_iovec(to))
1440                 return -EINVAL;
1441 
1442         fuse_copy_init(&cs, 1, to);
1443 
1444         return fuse_dev_do_read(fud, file, &cs, iov_iter_count(to));
1445 }
1446 
1447 static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
1448                                     struct pipe_inode_info *pipe,
1449                                     size_t len, unsigned int flags)
1450 {
1451         int total, ret;
1452         int page_nr = 0;
1453         struct pipe_buffer *bufs;
1454         struct fuse_copy_state cs;
1455         struct fuse_dev *fud = fuse_get_dev(in);
1456 
1457         if (!fud)
1458                 return -EPERM;
1459 
1460         bufs = kvmalloc_array(pipe->buffers, sizeof(struct pipe_buffer),
1461                               GFP_KERNEL);
1462         if (!bufs)
1463                 return -ENOMEM;
1464 
1465         fuse_copy_init(&cs, 1, NULL);
1466         cs.pipebufs = bufs;
1467         cs.pipe = pipe;
1468         ret = fuse_dev_do_read(fud, in, &cs, len);
1469         if (ret < 0)
1470                 goto out;
1471 
1472         if (pipe->nrbufs + cs.nr_segs > pipe->buffers) {
1473                 ret = -EIO;
1474                 goto out;
1475         }
1476 
1477         for (ret = total = 0; page_nr < cs.nr_segs; total += ret) {
1478                 /*
1479                  * Need to be careful about this.  Having buf->ops in module
1480                  * code can Oops if the buffer persists after module unload.
1481                  */
1482                 bufs[page_nr].ops = &nosteal_pipe_buf_ops;
1483                 bufs[page_nr].flags = 0;
1484                 ret = add_to_pipe(pipe, &bufs[page_nr++]);
1485                 if (unlikely(ret < 0))
1486                         break;
1487         }
1488         if (total)
1489                 ret = total;
1490 out:
1491         for (; page_nr < cs.nr_segs; page_nr++)
1492                 put_page(bufs[page_nr].page);
1493 
1494         kvfree(bufs);
1495         return ret;
1496 }
1497 
1498 static int fuse_notify_poll(struct fuse_conn *fc, unsigned int size,
1499                             struct fuse_copy_state *cs)
1500 {
1501         struct fuse_notify_poll_wakeup_out outarg;
1502         int err = -EINVAL;
1503 
1504         if (size != sizeof(outarg))
1505                 goto err;
1506 
1507         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1508         if (err)
1509                 goto err;
1510 
1511         fuse_copy_finish(cs);
1512         return fuse_notify_poll_wakeup(fc, &outarg);
1513 
1514 err:
1515         fuse_copy_finish(cs);
1516         return err;
1517 }
1518 
1519 static int fuse_notify_inval_inode(struct fuse_conn *fc, unsigned int size,
1520                                    struct fuse_copy_state *cs)
1521 {
1522         struct fuse_notify_inval_inode_out outarg;
1523         int err = -EINVAL;
1524 
1525         if (size != sizeof(outarg))
1526                 goto err;
1527 
1528         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1529         if (err)
1530                 goto err;
1531         fuse_copy_finish(cs);
1532 
1533         down_read(&fc->killsb);
1534         err = -ENOENT;
1535         if (fc->sb) {
1536                 err = fuse_reverse_inval_inode(fc->sb, outarg.ino,
1537                                                outarg.off, outarg.len);
1538         }
1539         up_read(&fc->killsb);
1540         return err;
1541 
1542 err:
1543         fuse_copy_finish(cs);
1544         return err;
1545 }
1546 
1547 static int fuse_notify_inval_entry(struct fuse_conn *fc, unsigned int size,
1548                                    struct fuse_copy_state *cs)
1549 {
1550         struct fuse_notify_inval_entry_out outarg;
1551         int err = -ENOMEM;
1552         char *buf;
1553         struct qstr name;
1554 
1555         buf = kzalloc(FUSE_NAME_MAX + 1, GFP_KERNEL);
1556         if (!buf)
1557                 goto err;
1558 
1559         err = -EINVAL;
1560         if (size < sizeof(outarg))
1561                 goto err;
1562 
1563         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1564         if (err)
1565                 goto err;
1566 
1567         err = -ENAMETOOLONG;
1568         if (outarg.namelen > FUSE_NAME_MAX)
1569                 goto err;
1570 
1571         err = -EINVAL;
1572         if (size != sizeof(outarg) + outarg.namelen + 1)
1573                 goto err;
1574 
1575         name.name = buf;
1576         name.len = outarg.namelen;
1577         err = fuse_copy_one(cs, buf, outarg.namelen + 1);
1578         if (err)
1579                 goto err;
1580         fuse_copy_finish(cs);
1581         buf[outarg.namelen] = 0;
1582 
1583         down_read(&fc->killsb);
1584         err = -ENOENT;
1585         if (fc->sb)
1586                 err = fuse_reverse_inval_entry(fc->sb, outarg.parent, 0, &name);
1587         up_read(&fc->killsb);
1588         kfree(buf);
1589         return err;
1590 
1591 err:
1592         kfree(buf);
1593         fuse_copy_finish(cs);
1594         return err;
1595 }
1596 
1597 static int fuse_notify_delete(struct fuse_conn *fc, unsigned int size,
1598                               struct fuse_copy_state *cs)
1599 {
1600         struct fuse_notify_delete_out outarg;
1601         int err = -ENOMEM;
1602         char *buf;
1603         struct qstr name;
1604 
1605         buf = kzalloc(FUSE_NAME_MAX + 1, GFP_KERNEL);
1606         if (!buf)
1607                 goto err;
1608 
1609         err = -EINVAL;
1610         if (size < sizeof(outarg))
1611                 goto err;
1612 
1613         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1614         if (err)
1615                 goto err;
1616 
1617         err = -ENAMETOOLONG;
1618         if (outarg.namelen > FUSE_NAME_MAX)
1619                 goto err;
1620 
1621         err = -EINVAL;
1622         if (size != sizeof(outarg) + outarg.namelen + 1)
1623                 goto err;
1624 
1625         name.name = buf;
1626         name.len = outarg.namelen;
1627         err = fuse_copy_one(cs, buf, outarg.namelen + 1);
1628         if (err)
1629                 goto err;
1630         fuse_copy_finish(cs);
1631         buf[outarg.namelen] = 0;
1632 
1633         down_read(&fc->killsb);
1634         err = -ENOENT;
1635         if (fc->sb)
1636                 err = fuse_reverse_inval_entry(fc->sb, outarg.parent,
1637                                                outarg.child, &name);
1638         up_read(&fc->killsb);
1639         kfree(buf);
1640         return err;
1641 
1642 err:
1643         kfree(buf);
1644         fuse_copy_finish(cs);
1645         return err;
1646 }
1647 
1648 static int fuse_notify_store(struct fuse_conn *fc, unsigned int size,
1649                              struct fuse_copy_state *cs)
1650 {
1651         struct fuse_notify_store_out outarg;
1652         struct inode *inode;
1653         struct address_space *mapping;
1654         u64 nodeid;
1655         int err;
1656         pgoff_t index;
1657         unsigned int offset;
1658         unsigned int num;
1659         loff_t file_size;
1660         loff_t end;
1661 
1662         err = -EINVAL;
1663         if (size < sizeof(outarg))
1664                 goto out_finish;
1665 
1666         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1667         if (err)
1668                 goto out_finish;
1669 
1670         err = -EINVAL;
1671         if (size - sizeof(outarg) != outarg.size)
1672                 goto out_finish;
1673 
1674         nodeid = outarg.nodeid;
1675 
1676         down_read(&fc->killsb);
1677 
1678         err = -ENOENT;
1679         if (!fc->sb)
1680                 goto out_up_killsb;
1681 
1682         inode = ilookup5(fc->sb, nodeid, fuse_inode_eq, &nodeid);
1683         if (!inode)
1684                 goto out_up_killsb;
1685 
1686         mapping = inode->i_mapping;
1687         index = outarg.offset >> PAGE_SHIFT;
1688         offset = outarg.offset & ~PAGE_MASK;
1689         file_size = i_size_read(inode);
1690         end = outarg.offset + outarg.size;
1691         if (end > file_size) {
1692                 file_size = end;
1693                 fuse_write_update_size(inode, file_size);
1694         }
1695 
1696         num = outarg.size;
1697         while (num) {
1698                 struct page *page;
1699                 unsigned int this_num;
1700 
1701                 err = -ENOMEM;
1702                 page = find_or_create_page(mapping, index,
1703                                            mapping_gfp_mask(mapping));
1704                 if (!page)
1705                         goto out_iput;
1706 
1707                 this_num = min_t(unsigned, num, PAGE_SIZE - offset);
1708                 err = fuse_copy_page(cs, &page, offset, this_num, 0);
1709                 if (!err && offset == 0 &&
1710                     (this_num == PAGE_SIZE || file_size == end))
1711                         SetPageUptodate(page);
1712                 unlock_page(page);
1713                 put_page(page);
1714 
1715                 if (err)
1716                         goto out_iput;
1717 
1718                 num -= this_num;
1719                 offset = 0;
1720                 index++;
1721         }
1722 
1723         err = 0;
1724 
1725 out_iput:
1726         iput(inode);
1727 out_up_killsb:
1728         up_read(&fc->killsb);
1729 out_finish:
1730         fuse_copy_finish(cs);
1731         return err;
1732 }
1733 
1734 static void fuse_retrieve_end(struct fuse_conn *fc, struct fuse_req *req)
1735 {
1736         release_pages(req->pages, req->num_pages);
1737 }
1738 
1739 static int fuse_retrieve(struct fuse_conn *fc, struct inode *inode,
1740                          struct fuse_notify_retrieve_out *outarg)
1741 {
1742         int err;
1743         struct address_space *mapping = inode->i_mapping;
1744         struct fuse_req *req;
1745         pgoff_t index;
1746         loff_t file_size;
1747         unsigned int num;
1748         unsigned int offset;
1749         size_t total_len = 0;
1750         unsigned int num_pages;
1751 
1752         offset = outarg->offset & ~PAGE_MASK;
1753         file_size = i_size_read(inode);
1754 
1755         num = min(outarg->size, fc->max_write);
1756         if (outarg->offset > file_size)
1757                 num = 0;
1758         else if (outarg->offset + num > file_size)
1759                 num = file_size - outarg->offset;
1760 
1761         num_pages = (num + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
1762         num_pages = min(num_pages, fc->max_pages);
1763 
1764         req = fuse_get_req(fc, num_pages);
1765         if (IS_ERR(req))
1766                 return PTR_ERR(req);
1767 
1768         req->in.h.opcode = FUSE_NOTIFY_REPLY;
1769         req->in.h.nodeid = outarg->nodeid;
1770         req->in.numargs = 2;
1771         req->in.argpages = 1;
1772         req->end = fuse_retrieve_end;
1773 
1774         index = outarg->offset >> PAGE_SHIFT;
1775 
1776         while (num && req->num_pages < num_pages) {
1777                 struct page *page;
1778                 unsigned int this_num;
1779 
1780                 page = find_get_page(mapping, index);
1781                 if (!page)
1782                         break;
1783 
1784                 this_num = min_t(unsigned, num, PAGE_SIZE - offset);
1785                 req->pages[req->num_pages] = page;
1786                 req->page_descs[req->num_pages].offset = offset;
1787                 req->page_descs[req->num_pages].length = this_num;
1788                 req->num_pages++;
1789 
1790                 offset = 0;
1791                 num -= this_num;
1792                 total_len += this_num;
1793                 index++;
1794         }
1795         req->misc.retrieve_in.offset = outarg->offset;
1796         req->misc.retrieve_in.size = total_len;
1797         req->in.args[0].size = sizeof(req->misc.retrieve_in);
1798         req->in.args[0].value = &req->misc.retrieve_in;
1799         req->in.args[1].size = total_len;
1800 
1801         err = fuse_request_send_notify_reply(fc, req, outarg->notify_unique);
1802         if (err) {
1803                 fuse_retrieve_end(fc, req);
1804                 fuse_put_request(fc, req);
1805         }
1806 
1807         return err;
1808 }
1809 
1810 static int fuse_notify_retrieve(struct fuse_conn *fc, unsigned int size,
1811                                 struct fuse_copy_state *cs)
1812 {
1813         struct fuse_notify_retrieve_out outarg;
1814         struct inode *inode;
1815         int err;
1816 
1817         err = -EINVAL;
1818         if (size != sizeof(outarg))
1819                 goto copy_finish;
1820 
1821         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
1822         if (err)
1823                 goto copy_finish;
1824 
1825         fuse_copy_finish(cs);
1826 
1827         down_read(&fc->killsb);
1828         err = -ENOENT;
1829         if (fc->sb) {
1830                 u64 nodeid = outarg.nodeid;
1831 
1832                 inode = ilookup5(fc->sb, nodeid, fuse_inode_eq, &nodeid);
1833                 if (inode) {
1834                         err = fuse_retrieve(fc, inode, &outarg);
1835                         iput(inode);
1836                 }
1837         }
1838         up_read(&fc->killsb);
1839 
1840         return err;
1841 
1842 copy_finish:
1843         fuse_copy_finish(cs);
1844         return err;
1845 }
1846 
1847 static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
1848                        unsigned int size, struct fuse_copy_state *cs)
1849 {
1850         /* Don't try to move pages (yet) */
1851         cs->move_pages = 0;
1852 
1853         switch (code) {
1854         case FUSE_NOTIFY_POLL:
1855                 return fuse_notify_poll(fc, size, cs);
1856 
1857         case FUSE_NOTIFY_INVAL_INODE:
1858                 return fuse_notify_inval_inode(fc, size, cs);
1859 
1860         case FUSE_NOTIFY_INVAL_ENTRY:
1861                 return fuse_notify_inval_entry(fc, size, cs);
1862 
1863         case FUSE_NOTIFY_STORE:
1864                 return fuse_notify_store(fc, size, cs);
1865 
1866         case FUSE_NOTIFY_RETRIEVE:
1867                 return fuse_notify_retrieve(fc, size, cs);
1868 
1869         case FUSE_NOTIFY_DELETE:
1870                 return fuse_notify_delete(fc, size, cs);
1871 
1872         default:
1873                 fuse_copy_finish(cs);
1874                 return -EINVAL;
1875         }
1876 }
1877 
1878 /* Look up request on processing list by unique ID */
1879 static struct fuse_req *request_find(struct fuse_pqueue *fpq, u64 unique)
1880 {
1881         unsigned int hash = fuse_req_hash(unique);
1882         struct fuse_req *req;
1883 
1884         list_for_each_entry(req, &fpq->processing[hash], list) {
1885                 if (req->in.h.unique == unique)
1886                         return req;
1887         }
1888         return NULL;
1889 }
1890 
1891 static int copy_out_args(struct fuse_copy_state *cs, struct fuse_out *out,
1892                          unsigned nbytes)
1893 {
1894         unsigned reqsize = sizeof(struct fuse_out_header);
1895 
1896         if (out->h.error)
1897                 return nbytes != reqsize ? -EINVAL : 0;
1898 
1899         reqsize += len_args(out->numargs, out->args);
1900 
1901         if (reqsize < nbytes || (reqsize > nbytes && !out->argvar))
1902                 return -EINVAL;
1903         else if (reqsize > nbytes) {
1904                 struct fuse_arg *lastarg = &out->args[out->numargs-1];
1905                 unsigned diffsize = reqsize - nbytes;
1906                 if (diffsize > lastarg->size)
1907                         return -EINVAL;
1908                 lastarg->size -= diffsize;
1909         }
1910         return fuse_copy_args(cs, out->numargs, out->argpages, out->args,
1911                               out->page_zeroing);
1912 }
1913 
1914 /*
1915  * Write a single reply to a request.  First the header is copied from
1916  * the write buffer.  The request is then searched on the processing
1917  * list by the unique ID found in the header.  If found, then remove
1918  * it from the list and copy the rest of the buffer to the request.
1919  * The request is finished by calling request_end()
1920  */
1921 static ssize_t fuse_dev_do_write(struct fuse_dev *fud,
1922                                  struct fuse_copy_state *cs, size_t nbytes)
1923 {
1924         int err;
1925         struct fuse_conn *fc = fud->fc;
1926         struct fuse_pqueue *fpq = &fud->pq;
1927         struct fuse_req *req;
1928         struct fuse_out_header oh;
1929 
1930         err = -EINVAL;
1931         if (nbytes < sizeof(struct fuse_out_header))
1932                 goto out;
1933 
1934         err = fuse_copy_one(cs, &oh, sizeof(oh));
1935         if (err)
1936                 goto copy_finish;
1937 
1938         err = -EINVAL;
1939         if (oh.len != nbytes)
1940                 goto copy_finish;
1941 
1942         /*
1943          * Zero oh.unique indicates unsolicited notification message
1944          * and error contains notification code.
1945          */
1946         if (!oh.unique) {
1947                 err = fuse_notify(fc, oh.error, nbytes - sizeof(oh), cs);
1948                 goto out;
1949         }
1950 
1951         err = -EINVAL;
1952         if (oh.error <= -1000 || oh.error > 0)
1953                 goto copy_finish;
1954 
1955         spin_lock(&fpq->lock);
1956         req = NULL;
1957         if (fpq->connected)
1958                 req = request_find(fpq, oh.unique & ~FUSE_INT_REQ_BIT);
1959 
1960         err = -ENOENT;
1961         if (!req) {
1962                 spin_unlock(&fpq->lock);
1963                 goto copy_finish;
1964         }
1965 
1966         /* Is it an interrupt reply ID? */
1967         if (oh.unique & FUSE_INT_REQ_BIT) {
1968                 __fuse_get_request(req);
1969                 spin_unlock(&fpq->lock);
1970 
1971                 err = 0;
1972                 if (nbytes != sizeof(struct fuse_out_header))
1973                         err = -EINVAL;
1974                 else if (oh.error == -ENOSYS)
1975                         fc->no_interrupt = 1;
1976                 else if (oh.error == -EAGAIN)
1977                         err = queue_interrupt(&fc->iq, req);
1978 
1979                 fuse_put_request(fc, req);
1980 
1981                 goto copy_finish;
1982         }
1983 
1984         clear_bit(FR_SENT, &req->flags);
1985         list_move(&req->list, &fpq->io);
1986         req->out.h = oh;
1987         set_bit(FR_LOCKED, &req->flags);
1988         spin_unlock(&fpq->lock);
1989         cs->req = req;
1990         if (!req->out.page_replace)
1991                 cs->move_pages = 0;
1992 
1993         err = copy_out_args(cs, &req->out, nbytes);
1994         fuse_copy_finish(cs);
1995 
1996         spin_lock(&fpq->lock);
1997         clear_bit(FR_LOCKED, &req->flags);
1998         if (!fpq->connected)
1999                 err = -ENOENT;
2000         else if (err)
2001                 req->out.h.error = -EIO;
2002         if (!test_bit(FR_PRIVATE, &req->flags))
2003                 list_del_init(&req->list);
2004         spin_unlock(&fpq->lock);
2005 
2006         request_end(fc, req);
2007 out:
2008         return err ? err : nbytes;
2009 
2010 copy_finish:
2011         fuse_copy_finish(cs);
2012         goto out;
2013 }
2014 
2015 static ssize_t fuse_dev_write(struct kiocb *iocb, struct iov_iter *from)
2016 {
2017         struct fuse_copy_state cs;
2018         struct fuse_dev *fud = fuse_get_dev(iocb->ki_filp);
2019 
2020         if (!fud)
2021                 return -EPERM;
2022 
2023         if (!iter_is_iovec(from))
2024                 return -EINVAL;
2025 
2026         fuse_copy_init(&cs, 0, from);
2027 
2028         return fuse_dev_do_write(fud, &cs, iov_iter_count(from));
2029 }
2030 
2031 static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
2032                                      struct file *out, loff_t *ppos,
2033                                      size_t len, unsigned int flags)
2034 {
2035         unsigned nbuf;
2036         unsigned idx;
2037         struct pipe_buffer *bufs;
2038         struct fuse_copy_state cs;
2039         struct fuse_dev *fud;
2040         size_t rem;
2041         ssize_t ret;
2042 
2043         fud = fuse_get_dev(out);
2044         if (!fud)
2045                 return -EPERM;
2046 
2047         pipe_lock(pipe);
2048 
2049         bufs = kvmalloc_array(pipe->nrbufs, sizeof(struct pipe_buffer),
2050                               GFP_KERNEL);
2051         if (!bufs) {
2052                 pipe_unlock(pipe);
2053                 return -ENOMEM;
2054         }
2055 
2056         nbuf = 0;
2057         rem = 0;
2058         for (idx = 0; idx < pipe->nrbufs && rem < len; idx++)
2059                 rem += pipe->bufs[(pipe->curbuf + idx) & (pipe->buffers - 1)].len;
2060 
2061         ret = -EINVAL;
2062         if (rem < len)
2063                 goto out_free;
2064 
2065         rem = len;
2066         while (rem) {
2067                 struct pipe_buffer *ibuf;
2068                 struct pipe_buffer *obuf;
2069 
2070                 BUG_ON(nbuf >= pipe->buffers);
2071                 BUG_ON(!pipe->nrbufs);
2072                 ibuf = &pipe->bufs[pipe->curbuf];
2073                 obuf = &bufs[nbuf];
2074 
2075                 if (rem >= ibuf->len) {
2076                         *obuf = *ibuf;
2077                         ibuf->ops = NULL;
2078                         pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
2079                         pipe->nrbufs--;
2080                 } else {
2081                         if (!pipe_buf_get(pipe, ibuf))
2082                                 goto out_free;
2083 
2084                         *obuf = *ibuf;
2085                         obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
2086                         obuf->len = rem;
2087                         ibuf->offset += obuf->len;
2088                         ibuf->len -= obuf->len;
2089                 }
2090                 nbuf++;
2091                 rem -= obuf->len;
2092         }
2093         pipe_unlock(pipe);
2094 
2095         fuse_copy_init(&cs, 0, NULL);
2096         cs.pipebufs = bufs;
2097         cs.nr_segs = nbuf;
2098         cs.pipe = pipe;
2099 
2100         if (flags & SPLICE_F_MOVE)
2101                 cs.move_pages = 1;
2102 
2103         ret = fuse_dev_do_write(fud, &cs, len);
2104 
2105         pipe_lock(pipe);
2106 out_free:
2107         for (idx = 0; idx < nbuf; idx++)
2108                 pipe_buf_release(pipe, &bufs[idx]);
2109         pipe_unlock(pipe);
2110 
2111         kvfree(bufs);
2112         return ret;
2113 }
2114 
2115 static __poll_t fuse_dev_poll(struct file *file, poll_table *wait)
2116 {
2117         __poll_t mask = EPOLLOUT | EPOLLWRNORM;
2118         struct fuse_iqueue *fiq;
2119         struct fuse_dev *fud = fuse_get_dev(file);
2120 
2121         if (!fud)
2122                 return EPOLLERR;
2123 
2124         fiq = &fud->fc->iq;
2125         poll_wait(file, &fiq->waitq, wait);
2126 
2127         spin_lock(&fiq->lock);
2128         if (!fiq->connected)
2129                 mask = EPOLLERR;
2130         else if (request_pending(fiq))
2131                 mask |= EPOLLIN | EPOLLRDNORM;
2132         spin_unlock(&fiq->lock);
2133 
2134         return mask;
2135 }
2136 
2137 /* Abort all requests on the given list (pending or processing) */
2138 static void end_requests(struct fuse_conn *fc, struct list_head *head)
2139 {
2140         while (!list_empty(head)) {
2141                 struct fuse_req *req;
2142                 req = list_entry(head->next, struct fuse_req, list);
2143                 req->out.h.error = -ECONNABORTED;
2144                 clear_bit(FR_SENT, &req->flags);
2145                 list_del_init(&req->list);
2146                 request_end(fc, req);
2147         }
2148 }
2149 
2150 static void end_polls(struct fuse_conn *fc)
2151 {
2152         struct rb_node *p;
2153 
2154         p = rb_first(&fc->polled_files);
2155 
2156         while (p) {
2157                 struct fuse_file *ff;
2158                 ff = rb_entry(p, struct fuse_file, polled_node);
2159                 wake_up_interruptible_all(&ff->poll_wait);
2160 
2161                 p = rb_next(p);
2162         }
2163 }
2164 
2165 /*
2166  * Abort all requests.
2167  *
2168  * Emergency exit in case of a malicious or accidental deadlock, or just a hung
2169  * filesystem.
2170  *
2171  * The same effect is usually achievable through killing the filesystem daemon
2172  * and all users of the filesystem.  The exception is the combination of an
2173  * asynchronous request and the tricky deadlock (see
2174  * Documentation/filesystems/fuse.txt).
2175  *
2176  * Aborting requests under I/O goes as follows: 1: Separate out unlocked
2177  * requests, they should be finished off immediately.  Locked requests will be
2178  * finished after unlock; see unlock_request(). 2: Finish off the unlocked
2179  * requests.  It is possible that some request will finish before we can.  This
2180  * is OK, the request will in that case be removed from the list before we touch
2181  * it.
2182  */
2183 void fuse_abort_conn(struct fuse_conn *fc)
2184 {
2185         struct fuse_iqueue *fiq = &fc->iq;
2186 
2187         spin_lock(&fc->lock);
2188         if (fc->connected) {
2189                 struct fuse_dev *fud;
2190                 struct fuse_req *req, *next;
2191                 LIST_HEAD(to_end);
2192                 unsigned int i;
2193 
2194                 /* Background queuing checks fc->connected under bg_lock */
2195                 spin_lock(&fc->bg_lock);
2196                 fc->connected = 0;
2197                 spin_unlock(&fc->bg_lock);
2198 
2199                 fuse_set_initialized(fc);
2200                 list_for_each_entry(fud, &fc->devices, entry) {
2201                         struct fuse_pqueue *fpq = &fud->pq;
2202 
2203                         spin_lock(&fpq->lock);
2204                         fpq->connected = 0;
2205                         list_for_each_entry_safe(req, next, &fpq->io, list) {
2206                                 req->out.h.error = -ECONNABORTED;
2207                                 spin_lock(&req->waitq.lock);
2208                                 set_bit(FR_ABORTED, &req->flags);
2209                                 if (!test_bit(FR_LOCKED, &req->flags)) {
2210                                         set_bit(FR_PRIVATE, &req->flags);
2211                                         __fuse_get_request(req);
2212                                         list_move(&req->list, &to_end);
2213                                 }
2214                                 spin_unlock(&req->waitq.lock);
2215                         }
2216                         for (i = 0; i < FUSE_PQ_HASH_SIZE; i++)
2217                                 list_splice_tail_init(&fpq->processing[i],
2218                                                       &to_end);
2219                         spin_unlock(&fpq->lock);
2220                 }
2221                 spin_lock(&fc->bg_lock);
2222                 fc->blocked = 0;
2223                 fc->max_background = UINT_MAX;
2224                 flush_bg_queue(fc);
2225                 spin_unlock(&fc->bg_lock);
2226 
2227                 spin_lock(&fiq->lock);
2228                 fiq->connected = 0;
2229                 list_for_each_entry(req, &fiq->pending, list)
2230                         clear_bit(FR_PENDING, &req->flags);
2231                 list_splice_tail_init(&fiq->pending, &to_end);
2232                 while (forget_pending(fiq))
2233                         kfree(dequeue_forget(fiq, 1, NULL));
2234                 wake_up_all(&fiq->waitq);
2235                 spin_unlock(&fiq->lock);
2236                 kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
2237                 end_polls(fc);
2238                 wake_up_all(&fc->blocked_waitq);
2239                 spin_unlock(&fc->lock);
2240 
2241                 end_requests(fc, &to_end);
2242         } else {
2243                 spin_unlock(&fc->lock);
2244         }
2245 }
2246 EXPORT_SYMBOL_GPL(fuse_abort_conn);
2247 
2248 void fuse_wait_aborted(struct fuse_conn *fc)
2249 {
2250         /* matches implicit memory barrier in fuse_drop_waiting() */
2251         smp_mb();
2252         wait_event(fc->blocked_waitq, atomic_read(&fc->num_waiting) == 0);
2253 }
2254 
2255 int fuse_dev_release(struct inode *inode, struct file *file)
2256 {
2257         struct fuse_dev *fud = fuse_get_dev(file);
2258 
2259         if (fud) {
2260                 struct fuse_conn *fc = fud->fc;
2261                 struct fuse_pqueue *fpq = &fud->pq;
2262                 LIST_HEAD(to_end);
2263                 unsigned int i;
2264 
2265                 spin_lock(&fpq->lock);
2266                 WARN_ON(!list_empty(&fpq->io));
2267                 for (i = 0; i < FUSE_PQ_HASH_SIZE; i++)
2268                         list_splice_init(&fpq->processing[i], &to_end);
2269                 spin_unlock(&fpq->lock);
2270 
2271                 end_requests(fc, &to_end);
2272 
2273                 /* Are we the last open device? */
2274                 if (atomic_dec_and_test(&fc->dev_count)) {
2275                         WARN_ON(fc->iq.fasync != NULL);
2276                         fuse_abort_conn(fc);
2277                 }
2278                 fuse_dev_free(fud);
2279         }
2280         return 0;
2281 }
2282 EXPORT_SYMBOL_GPL(fuse_dev_release);
2283 
2284 static int fuse_dev_fasync(int fd, struct file *file, int on)
2285 {
2286         struct fuse_dev *fud = fuse_get_dev(file);
2287 
2288         if (!fud)
2289                 return -EPERM;
2290 
2291         /* No locking - fasync_helper does its own locking */
2292         return fasync_helper(fd, file, on, &fud->fc->iq.fasync);
2293 }
2294 
2295 static int fuse_device_clone(struct fuse_conn *fc, struct file *new)
2296 {
2297         struct fuse_dev *fud;
2298 
2299         if (new->private_data)
2300                 return -EINVAL;
2301 
2302         fud = fuse_dev_alloc(fc);
2303         if (!fud)
2304                 return -ENOMEM;
2305 
2306         new->private_data = fud;
2307         atomic_inc(&fc->dev_count);
2308 
2309         return 0;
2310 }
2311 
2312 static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
2313                            unsigned long arg)
2314 {
2315         int err = -ENOTTY;
2316 
2317         if (cmd == FUSE_DEV_IOC_CLONE) {
2318                 int oldfd;
2319 
2320                 err = -EFAULT;
2321                 if (!get_user(oldfd, (__u32 __user *) arg)) {
2322                         struct file *old = fget(oldfd);
2323 
2324                         err = -EINVAL;
2325                         if (old) {
2326                                 struct fuse_dev *fud = NULL;
2327 
2328                                 /*
2329                                  * Check against file->f_op because CUSE
2330                                  * uses the same ioctl handler.
2331                                  */
2332                                 if (old->f_op == file->f_op &&
2333                                     old->f_cred->user_ns == file->f_cred->user_ns)
2334                                         fud = fuse_get_dev(old);
2335 
2336                                 if (fud) {
2337                                         mutex_lock(&fuse_mutex);
2338                                         err = fuse_device_clone(fud->fc, file);
2339                                         mutex_unlock(&fuse_mutex);
2340                                 }
2341                                 fput(old);
2342                         }
2343                 }
2344         }
2345         return err;
2346 }
2347 
2348 const struct file_operations fuse_dev_operations = {
2349         .owner          = THIS_MODULE,
2350         .open           = fuse_dev_open,
2351         .llseek         = no_llseek,
2352         .read_iter      = fuse_dev_read,
2353         .splice_read    = fuse_dev_splice_read,
2354         .write_iter     = fuse_dev_write,
2355         .splice_write   = fuse_dev_splice_write,
2356         .poll           = fuse_dev_poll,
2357         .release        = fuse_dev_release,
2358         .fasync         = fuse_dev_fasync,
2359         .unlocked_ioctl = fuse_dev_ioctl,
2360         .compat_ioctl   = fuse_dev_ioctl,
2361 };
2362 EXPORT_SYMBOL_GPL(fuse_dev_operations);
2363 
2364 static struct miscdevice fuse_miscdevice = {
2365         .minor = FUSE_MINOR,
2366         .name  = "fuse",
2367         .fops = &fuse_dev_operations,
2368 };
2369 
2370 int __init fuse_dev_init(void)
2371 {
2372         int err = -ENOMEM;
2373         fuse_req_cachep = kmem_cache_create("fuse_request",
2374                                             sizeof(struct fuse_req),
2375                                             0, 0, NULL);
2376         if (!fuse_req_cachep)
2377                 goto out;
2378 
2379         err = misc_register(&fuse_miscdevice);
2380         if (err)
2381                 goto out_cache_clean;
2382 
2383         return 0;
2384 
2385  out_cache_clean:
2386         kmem_cache_destroy(fuse_req_cachep);
2387  out:
2388         return err;
2389 }
2390 
2391 void fuse_dev_cleanup(void)
2392 {
2393         misc_deregister(&fuse_miscdevice);
2394         kmem_cache_destroy(fuse_req_cachep);
2395 }
2396 

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