Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/sameo/mfd-2.6
[linux-2.6.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/uio.h>
15 #include <linux/miscdevice.h>
16 #include <linux/pagemap.h>
17 #include <linux/file.h>
18 #include <linux/slab.h>
19
20 MODULE_ALIAS_MISCDEV(FUSE_MINOR);
21
22 static struct kmem_cache *fuse_req_cachep;
23
24 static struct fuse_conn *fuse_get_conn(struct file *file)
25 {
26         /*
27          * Lockless access is OK, because file->private data is set
28          * once during mount and is valid until the file is released.
29          */
30         return file->private_data;
31 }
32
33 static void fuse_request_init(struct fuse_req *req)
34 {
35         memset(req, 0, sizeof(*req));
36         INIT_LIST_HEAD(&req->list);
37         INIT_LIST_HEAD(&req->intr_entry);
38         init_waitqueue_head(&req->waitq);
39         atomic_set(&req->count, 1);
40 }
41
42 struct fuse_req *fuse_request_alloc(void)
43 {
44         struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, GFP_KERNEL);
45         if (req)
46                 fuse_request_init(req);
47         return req;
48 }
49 EXPORT_SYMBOL_GPL(fuse_request_alloc);
50
51 struct fuse_req *fuse_request_alloc_nofs(void)
52 {
53         struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, GFP_NOFS);
54         if (req)
55                 fuse_request_init(req);
56         return req;
57 }
58
59 void fuse_request_free(struct fuse_req *req)
60 {
61         kmem_cache_free(fuse_req_cachep, req);
62 }
63
64 static void block_sigs(sigset_t *oldset)
65 {
66         sigset_t mask;
67
68         siginitsetinv(&mask, sigmask(SIGKILL));
69         sigprocmask(SIG_BLOCK, &mask, oldset);
70 }
71
72 static void restore_sigs(sigset_t *oldset)
73 {
74         sigprocmask(SIG_SETMASK, oldset, NULL);
75 }
76
77 static void __fuse_get_request(struct fuse_req *req)
78 {
79         atomic_inc(&req->count);
80 }
81
82 /* Must be called with > 1 refcount */
83 static void __fuse_put_request(struct fuse_req *req)
84 {
85         BUG_ON(atomic_read(&req->count) < 2);
86         atomic_dec(&req->count);
87 }
88
89 static void fuse_req_init_context(struct fuse_req *req)
90 {
91         req->in.h.uid = current_fsuid();
92         req->in.h.gid = current_fsgid();
93         req->in.h.pid = current->pid;
94 }
95
96 struct fuse_req *fuse_get_req(struct fuse_conn *fc)
97 {
98         struct fuse_req *req;
99         sigset_t oldset;
100         int intr;
101         int err;
102
103         atomic_inc(&fc->num_waiting);
104         block_sigs(&oldset);
105         intr = wait_event_interruptible(fc->blocked_waitq, !fc->blocked);
106         restore_sigs(&oldset);
107         err = -EINTR;
108         if (intr)
109                 goto out;
110
111         err = -ENOTCONN;
112         if (!fc->connected)
113                 goto out;
114
115         req = fuse_request_alloc();
116         err = -ENOMEM;
117         if (!req)
118                 goto out;
119
120         fuse_req_init_context(req);
121         req->waiting = 1;
122         return req;
123
124  out:
125         atomic_dec(&fc->num_waiting);
126         return ERR_PTR(err);
127 }
128 EXPORT_SYMBOL_GPL(fuse_get_req);
129
130 /*
131  * Return request in fuse_file->reserved_req.  However that may
132  * currently be in use.  If that is the case, wait for it to become
133  * available.
134  */
135 static struct fuse_req *get_reserved_req(struct fuse_conn *fc,
136                                          struct file *file)
137 {
138         struct fuse_req *req = NULL;
139         struct fuse_file *ff = file->private_data;
140
141         do {
142                 wait_event(fc->reserved_req_waitq, ff->reserved_req);
143                 spin_lock(&fc->lock);
144                 if (ff->reserved_req) {
145                         req = ff->reserved_req;
146                         ff->reserved_req = NULL;
147                         get_file(file);
148                         req->stolen_file = file;
149                 }
150                 spin_unlock(&fc->lock);
151         } while (!req);
152
153         return req;
154 }
155
156 /*
157  * Put stolen request back into fuse_file->reserved_req
158  */
159 static void put_reserved_req(struct fuse_conn *fc, struct fuse_req *req)
160 {
161         struct file *file = req->stolen_file;
162         struct fuse_file *ff = file->private_data;
163
164         spin_lock(&fc->lock);
165         fuse_request_init(req);
166         BUG_ON(ff->reserved_req);
167         ff->reserved_req = req;
168         wake_up_all(&fc->reserved_req_waitq);
169         spin_unlock(&fc->lock);
170         fput(file);
171 }
172
173 /*
174  * Gets a requests for a file operation, always succeeds
175  *
176  * This is used for sending the FLUSH request, which must get to
177  * userspace, due to POSIX locks which may need to be unlocked.
178  *
179  * If allocation fails due to OOM, use the reserved request in
180  * fuse_file.
181  *
182  * This is very unlikely to deadlock accidentally, since the
183  * filesystem should not have it's own file open.  If deadlock is
184  * intentional, it can still be broken by "aborting" the filesystem.
185  */
186 struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file)
187 {
188         struct fuse_req *req;
189
190         atomic_inc(&fc->num_waiting);
191         wait_event(fc->blocked_waitq, !fc->blocked);
192         req = fuse_request_alloc();
193         if (!req)
194                 req = get_reserved_req(fc, file);
195
196         fuse_req_init_context(req);
197         req->waiting = 1;
198         return req;
199 }
200
201 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
202 {
203         if (atomic_dec_and_test(&req->count)) {
204                 if (req->waiting)
205                         atomic_dec(&fc->num_waiting);
206
207                 if (req->stolen_file)
208                         put_reserved_req(fc, req);
209                 else
210                         fuse_request_free(req);
211         }
212 }
213 EXPORT_SYMBOL_GPL(fuse_put_request);
214
215 static unsigned len_args(unsigned numargs, struct fuse_arg *args)
216 {
217         unsigned nbytes = 0;
218         unsigned i;
219
220         for (i = 0; i < numargs; i++)
221                 nbytes += args[i].size;
222
223         return nbytes;
224 }
225
226 static u64 fuse_get_unique(struct fuse_conn *fc)
227 {
228         fc->reqctr++;
229         /* zero is special */
230         if (fc->reqctr == 0)
231                 fc->reqctr = 1;
232
233         return fc->reqctr;
234 }
235
236 static void queue_request(struct fuse_conn *fc, struct fuse_req *req)
237 {
238         req->in.h.unique = fuse_get_unique(fc);
239         req->in.h.len = sizeof(struct fuse_in_header) +
240                 len_args(req->in.numargs, (struct fuse_arg *) req->in.args);
241         list_add_tail(&req->list, &fc->pending);
242         req->state = FUSE_REQ_PENDING;
243         if (!req->waiting) {
244                 req->waiting = 1;
245                 atomic_inc(&fc->num_waiting);
246         }
247         wake_up(&fc->waitq);
248         kill_fasync(&fc->fasync, SIGIO, POLL_IN);
249 }
250
251 static void flush_bg_queue(struct fuse_conn *fc)
252 {
253         while (fc->active_background < FUSE_MAX_BACKGROUND &&
254                !list_empty(&fc->bg_queue)) {
255                 struct fuse_req *req;
256
257                 req = list_entry(fc->bg_queue.next, struct fuse_req, list);
258                 list_del(&req->list);
259                 fc->active_background++;
260                 queue_request(fc, req);
261         }
262 }
263
264 /*
265  * This function is called when a request is finished.  Either a reply
266  * has arrived or it was aborted (and not yet sent) or some error
267  * occurred during communication with userspace, or the device file
268  * was closed.  The requester thread is woken up (if still waiting),
269  * the 'end' callback is called if given, else the reference to the
270  * request is released
271  *
272  * Called with fc->lock, unlocks it
273  */
274 static void request_end(struct fuse_conn *fc, struct fuse_req *req)
275 __releases(&fc->lock)
276 {
277         void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
278         req->end = NULL;
279         list_del(&req->list);
280         list_del(&req->intr_entry);
281         req->state = FUSE_REQ_FINISHED;
282         if (req->background) {
283                 if (fc->num_background == FUSE_MAX_BACKGROUND) {
284                         fc->blocked = 0;
285                         wake_up_all(&fc->blocked_waitq);
286                 }
287                 if (fc->num_background == FUSE_CONGESTION_THRESHOLD &&
288                     fc->connected && fc->bdi_initialized) {
289                         clear_bdi_congested(&fc->bdi, BLK_RW_SYNC);
290                         clear_bdi_congested(&fc->bdi, BLK_RW_ASYNC);
291                 }
292                 fc->num_background--;
293                 fc->active_background--;
294                 flush_bg_queue(fc);
295         }
296         spin_unlock(&fc->lock);
297         wake_up(&req->waitq);
298         if (end)
299                 end(fc, req);
300         fuse_put_request(fc, req);
301 }
302
303 static void wait_answer_interruptible(struct fuse_conn *fc,
304                                       struct fuse_req *req)
305 __releases(&fc->lock)
306 __acquires(&fc->lock)
307 {
308         if (signal_pending(current))
309                 return;
310
311         spin_unlock(&fc->lock);
312         wait_event_interruptible(req->waitq, req->state == FUSE_REQ_FINISHED);
313         spin_lock(&fc->lock);
314 }
315
316 static void queue_interrupt(struct fuse_conn *fc, struct fuse_req *req)
317 {
318         list_add_tail(&req->intr_entry, &fc->interrupts);
319         wake_up(&fc->waitq);
320         kill_fasync(&fc->fasync, SIGIO, POLL_IN);
321 }
322
323 static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
324 __releases(&fc->lock)
325 __acquires(&fc->lock)
326 {
327         if (!fc->no_interrupt) {
328                 /* Any signal may interrupt this */
329                 wait_answer_interruptible(fc, req);
330
331                 if (req->aborted)
332                         goto aborted;
333                 if (req->state == FUSE_REQ_FINISHED)
334                         return;
335
336                 req->interrupted = 1;
337                 if (req->state == FUSE_REQ_SENT)
338                         queue_interrupt(fc, req);
339         }
340
341         if (!req->force) {
342                 sigset_t oldset;
343
344                 /* Only fatal signals may interrupt this */
345                 block_sigs(&oldset);
346                 wait_answer_interruptible(fc, req);
347                 restore_sigs(&oldset);
348
349                 if (req->aborted)
350                         goto aborted;
351                 if (req->state == FUSE_REQ_FINISHED)
352                         return;
353
354                 /* Request is not yet in userspace, bail out */
355                 if (req->state == FUSE_REQ_PENDING) {
356                         list_del(&req->list);
357                         __fuse_put_request(req);
358                         req->out.h.error = -EINTR;
359                         return;
360                 }
361         }
362
363         /*
364          * Either request is already in userspace, or it was forced.
365          * Wait it out.
366          */
367         spin_unlock(&fc->lock);
368         wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
369         spin_lock(&fc->lock);
370
371         if (!req->aborted)
372                 return;
373
374  aborted:
375         BUG_ON(req->state != FUSE_REQ_FINISHED);
376         if (req->locked) {
377                 /* This is uninterruptible sleep, because data is
378                    being copied to/from the buffers of req.  During
379                    locked state, there mustn't be any filesystem
380                    operation (e.g. page fault), since that could lead
381                    to deadlock */
382                 spin_unlock(&fc->lock);
383                 wait_event(req->waitq, !req->locked);
384                 spin_lock(&fc->lock);
385         }
386 }
387
388 void fuse_request_send(struct fuse_conn *fc, struct fuse_req *req)
389 {
390         req->isreply = 1;
391         spin_lock(&fc->lock);
392         if (!fc->connected)
393                 req->out.h.error = -ENOTCONN;
394         else if (fc->conn_error)
395                 req->out.h.error = -ECONNREFUSED;
396         else {
397                 queue_request(fc, req);
398                 /* acquire extra reference, since request is still needed
399                    after request_end() */
400                 __fuse_get_request(req);
401
402                 request_wait_answer(fc, req);
403         }
404         spin_unlock(&fc->lock);
405 }
406 EXPORT_SYMBOL_GPL(fuse_request_send);
407
408 static void fuse_request_send_nowait_locked(struct fuse_conn *fc,
409                                             struct fuse_req *req)
410 {
411         req->background = 1;
412         fc->num_background++;
413         if (fc->num_background == FUSE_MAX_BACKGROUND)
414                 fc->blocked = 1;
415         if (fc->num_background == FUSE_CONGESTION_THRESHOLD &&
416             fc->bdi_initialized) {
417                 set_bdi_congested(&fc->bdi, BLK_RW_SYNC);
418                 set_bdi_congested(&fc->bdi, BLK_RW_ASYNC);
419         }
420         list_add_tail(&req->list, &fc->bg_queue);
421         flush_bg_queue(fc);
422 }
423
424 static void fuse_request_send_nowait(struct fuse_conn *fc, struct fuse_req *req)
425 {
426         spin_lock(&fc->lock);
427         if (fc->connected) {
428                 fuse_request_send_nowait_locked(fc, req);
429                 spin_unlock(&fc->lock);
430         } else {
431                 req->out.h.error = -ENOTCONN;
432                 request_end(fc, req);
433         }
434 }
435
436 void fuse_request_send_noreply(struct fuse_conn *fc, struct fuse_req *req)
437 {
438         req->isreply = 0;
439         fuse_request_send_nowait(fc, req);
440 }
441
442 void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req)
443 {
444         req->isreply = 1;
445         fuse_request_send_nowait(fc, req);
446 }
447 EXPORT_SYMBOL_GPL(fuse_request_send_background);
448
449 /*
450  * Called under fc->lock
451  *
452  * fc->connected must have been checked previously
453  */
454 void fuse_request_send_background_locked(struct fuse_conn *fc,
455                                          struct fuse_req *req)
456 {
457         req->isreply = 1;
458         fuse_request_send_nowait_locked(fc, req);
459 }
460
461 /*
462  * Lock the request.  Up to the next unlock_request() there mustn't be
463  * anything that could cause a page-fault.  If the request was already
464  * aborted bail out.
465  */
466 static int lock_request(struct fuse_conn *fc, struct fuse_req *req)
467 {
468         int err = 0;
469         if (req) {
470                 spin_lock(&fc->lock);
471                 if (req->aborted)
472                         err = -ENOENT;
473                 else
474                         req->locked = 1;
475                 spin_unlock(&fc->lock);
476         }
477         return err;
478 }
479
480 /*
481  * Unlock request.  If it was aborted during being locked, the
482  * requester thread is currently waiting for it to be unlocked, so
483  * wake it up.
484  */
485 static void unlock_request(struct fuse_conn *fc, struct fuse_req *req)
486 {
487         if (req) {
488                 spin_lock(&fc->lock);
489                 req->locked = 0;
490                 if (req->aborted)
491                         wake_up(&req->waitq);
492                 spin_unlock(&fc->lock);
493         }
494 }
495
496 struct fuse_copy_state {
497         struct fuse_conn *fc;
498         int write;
499         struct fuse_req *req;
500         const struct iovec *iov;
501         unsigned long nr_segs;
502         unsigned long seglen;
503         unsigned long addr;
504         struct page *pg;
505         void *mapaddr;
506         void *buf;
507         unsigned len;
508 };
509
510 static void fuse_copy_init(struct fuse_copy_state *cs, struct fuse_conn *fc,
511                            int write, struct fuse_req *req,
512                            const struct iovec *iov, unsigned long nr_segs)
513 {
514         memset(cs, 0, sizeof(*cs));
515         cs->fc = fc;
516         cs->write = write;
517         cs->req = req;
518         cs->iov = iov;
519         cs->nr_segs = nr_segs;
520 }
521
522 /* Unmap and put previous page of userspace buffer */
523 static void fuse_copy_finish(struct fuse_copy_state *cs)
524 {
525         if (cs->mapaddr) {
526                 kunmap_atomic(cs->mapaddr, KM_USER0);
527                 if (cs->write) {
528                         flush_dcache_page(cs->pg);
529                         set_page_dirty_lock(cs->pg);
530                 }
531                 put_page(cs->pg);
532                 cs->mapaddr = NULL;
533         }
534 }
535
536 /*
537  * Get another pagefull of userspace buffer, and map it to kernel
538  * address space, and lock request
539  */
540 static int fuse_copy_fill(struct fuse_copy_state *cs)
541 {
542         unsigned long offset;
543         int err;
544
545         unlock_request(cs->fc, cs->req);
546         fuse_copy_finish(cs);
547         if (!cs->seglen) {
548                 BUG_ON(!cs->nr_segs);
549                 cs->seglen = cs->iov[0].iov_len;
550                 cs->addr = (unsigned long) cs->iov[0].iov_base;
551                 cs->iov++;
552                 cs->nr_segs--;
553         }
554         down_read(&current->mm->mmap_sem);
555         err = get_user_pages(current, current->mm, cs->addr, 1, cs->write, 0,
556                              &cs->pg, NULL);
557         up_read(&current->mm->mmap_sem);
558         if (err < 0)
559                 return err;
560         BUG_ON(err != 1);
561         offset = cs->addr % PAGE_SIZE;
562         cs->mapaddr = kmap_atomic(cs->pg, KM_USER0);
563         cs->buf = cs->mapaddr + offset;
564         cs->len = min(PAGE_SIZE - offset, cs->seglen);
565         cs->seglen -= cs->len;
566         cs->addr += cs->len;
567
568         return lock_request(cs->fc, cs->req);
569 }
570
571 /* Do as much copy to/from userspace buffer as we can */
572 static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
573 {
574         unsigned ncpy = min(*size, cs->len);
575         if (val) {
576                 if (cs->write)
577                         memcpy(cs->buf, *val, ncpy);
578                 else
579                         memcpy(*val, cs->buf, ncpy);
580                 *val += ncpy;
581         }
582         *size -= ncpy;
583         cs->len -= ncpy;
584         cs->buf += ncpy;
585         return ncpy;
586 }
587
588 /*
589  * Copy a page in the request to/from the userspace buffer.  Must be
590  * done atomically
591  */
592 static int fuse_copy_page(struct fuse_copy_state *cs, struct page *page,
593                           unsigned offset, unsigned count, int zeroing)
594 {
595         if (page && zeroing && count < PAGE_SIZE) {
596                 void *mapaddr = kmap_atomic(page, KM_USER1);
597                 memset(mapaddr, 0, PAGE_SIZE);
598                 kunmap_atomic(mapaddr, KM_USER1);
599         }
600         while (count) {
601                 if (!cs->len) {
602                         int err = fuse_copy_fill(cs);
603                         if (err)
604                                 return err;
605                 }
606                 if (page) {
607                         void *mapaddr = kmap_atomic(page, KM_USER1);
608                         void *buf = mapaddr + offset;
609                         offset += fuse_copy_do(cs, &buf, &count);
610                         kunmap_atomic(mapaddr, KM_USER1);
611                 } else
612                         offset += fuse_copy_do(cs, NULL, &count);
613         }
614         if (page && !cs->write)
615                 flush_dcache_page(page);
616         return 0;
617 }
618
619 /* Copy pages in the request to/from userspace buffer */
620 static int fuse_copy_pages(struct fuse_copy_state *cs, unsigned nbytes,
621                            int zeroing)
622 {
623         unsigned i;
624         struct fuse_req *req = cs->req;
625         unsigned offset = req->page_offset;
626         unsigned count = min(nbytes, (unsigned) PAGE_SIZE - offset);
627
628         for (i = 0; i < req->num_pages && (nbytes || zeroing); i++) {
629                 struct page *page = req->pages[i];
630                 int err = fuse_copy_page(cs, page, offset, count, zeroing);
631                 if (err)
632                         return err;
633
634                 nbytes -= count;
635                 count = min(nbytes, (unsigned) PAGE_SIZE);
636                 offset = 0;
637         }
638         return 0;
639 }
640
641 /* Copy a single argument in the request to/from userspace buffer */
642 static int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned size)
643 {
644         while (size) {
645                 if (!cs->len) {
646                         int err = fuse_copy_fill(cs);
647                         if (err)
648                                 return err;
649                 }
650                 fuse_copy_do(cs, &val, &size);
651         }
652         return 0;
653 }
654
655 /* Copy request arguments to/from userspace buffer */
656 static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs,
657                           unsigned argpages, struct fuse_arg *args,
658                           int zeroing)
659 {
660         int err = 0;
661         unsigned i;
662
663         for (i = 0; !err && i < numargs; i++)  {
664                 struct fuse_arg *arg = &args[i];
665                 if (i == numargs - 1 && argpages)
666                         err = fuse_copy_pages(cs, arg->size, zeroing);
667                 else
668                         err = fuse_copy_one(cs, arg->value, arg->size);
669         }
670         return err;
671 }
672
673 static int request_pending(struct fuse_conn *fc)
674 {
675         return !list_empty(&fc->pending) || !list_empty(&fc->interrupts);
676 }
677
678 /* Wait until a request is available on the pending list */
679 static void request_wait(struct fuse_conn *fc)
680 __releases(&fc->lock)
681 __acquires(&fc->lock)
682 {
683         DECLARE_WAITQUEUE(wait, current);
684
685         add_wait_queue_exclusive(&fc->waitq, &wait);
686         while (fc->connected && !request_pending(fc)) {
687                 set_current_state(TASK_INTERRUPTIBLE);
688                 if (signal_pending(current))
689                         break;
690
691                 spin_unlock(&fc->lock);
692                 schedule();
693                 spin_lock(&fc->lock);
694         }
695         set_current_state(TASK_RUNNING);
696         remove_wait_queue(&fc->waitq, &wait);
697 }
698
699 /*
700  * Transfer an interrupt request to userspace
701  *
702  * Unlike other requests this is assembled on demand, without a need
703  * to allocate a separate fuse_req structure.
704  *
705  * Called with fc->lock held, releases it
706  */
707 static int fuse_read_interrupt(struct fuse_conn *fc, struct fuse_req *req,
708                                const struct iovec *iov, unsigned long nr_segs)
709 __releases(&fc->lock)
710 {
711         struct fuse_copy_state cs;
712         struct fuse_in_header ih;
713         struct fuse_interrupt_in arg;
714         unsigned reqsize = sizeof(ih) + sizeof(arg);
715         int err;
716
717         list_del_init(&req->intr_entry);
718         req->intr_unique = fuse_get_unique(fc);
719         memset(&ih, 0, sizeof(ih));
720         memset(&arg, 0, sizeof(arg));
721         ih.len = reqsize;
722         ih.opcode = FUSE_INTERRUPT;
723         ih.unique = req->intr_unique;
724         arg.unique = req->in.h.unique;
725
726         spin_unlock(&fc->lock);
727         if (iov_length(iov, nr_segs) < reqsize)
728                 return -EINVAL;
729
730         fuse_copy_init(&cs, fc, 1, NULL, iov, nr_segs);
731         err = fuse_copy_one(&cs, &ih, sizeof(ih));
732         if (!err)
733                 err = fuse_copy_one(&cs, &arg, sizeof(arg));
734         fuse_copy_finish(&cs);
735
736         return err ? err : reqsize;
737 }
738
739 /*
740  * Read a single request into the userspace filesystem's buffer.  This
741  * function waits until a request is available, then removes it from
742  * the pending list and copies request data to userspace buffer.  If
743  * no reply is needed (FORGET) or request has been aborted or there
744  * was an error during the copying then it's finished by calling
745  * request_end().  Otherwise add it to the processing list, and set
746  * the 'sent' flag.
747  */
748 static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
749                               unsigned long nr_segs, loff_t pos)
750 {
751         int err;
752         struct fuse_req *req;
753         struct fuse_in *in;
754         struct fuse_copy_state cs;
755         unsigned reqsize;
756         struct file *file = iocb->ki_filp;
757         struct fuse_conn *fc = fuse_get_conn(file);
758         if (!fc)
759                 return -EPERM;
760
761  restart:
762         spin_lock(&fc->lock);
763         err = -EAGAIN;
764         if ((file->f_flags & O_NONBLOCK) && fc->connected &&
765             !request_pending(fc))
766                 goto err_unlock;
767
768         request_wait(fc);
769         err = -ENODEV;
770         if (!fc->connected)
771                 goto err_unlock;
772         err = -ERESTARTSYS;
773         if (!request_pending(fc))
774                 goto err_unlock;
775
776         if (!list_empty(&fc->interrupts)) {
777                 req = list_entry(fc->interrupts.next, struct fuse_req,
778                                  intr_entry);
779                 return fuse_read_interrupt(fc, req, iov, nr_segs);
780         }
781
782         req = list_entry(fc->pending.next, struct fuse_req, list);
783         req->state = FUSE_REQ_READING;
784         list_move(&req->list, &fc->io);
785
786         in = &req->in;
787         reqsize = in->h.len;
788         /* If request is too large, reply with an error and restart the read */
789         if (iov_length(iov, nr_segs) < reqsize) {
790                 req->out.h.error = -EIO;
791                 /* SETXATTR is special, since it may contain too large data */
792                 if (in->h.opcode == FUSE_SETXATTR)
793                         req->out.h.error = -E2BIG;
794                 request_end(fc, req);
795                 goto restart;
796         }
797         spin_unlock(&fc->lock);
798         fuse_copy_init(&cs, fc, 1, req, iov, nr_segs);
799         err = fuse_copy_one(&cs, &in->h, sizeof(in->h));
800         if (!err)
801                 err = fuse_copy_args(&cs, in->numargs, in->argpages,
802                                      (struct fuse_arg *) in->args, 0);
803         fuse_copy_finish(&cs);
804         spin_lock(&fc->lock);
805         req->locked = 0;
806         if (req->aborted) {
807                 request_end(fc, req);
808                 return -ENODEV;
809         }
810         if (err) {
811                 req->out.h.error = -EIO;
812                 request_end(fc, req);
813                 return err;
814         }
815         if (!req->isreply)
816                 request_end(fc, req);
817         else {
818                 req->state = FUSE_REQ_SENT;
819                 list_move_tail(&req->list, &fc->processing);
820                 if (req->interrupted)
821                         queue_interrupt(fc, req);
822                 spin_unlock(&fc->lock);
823         }
824         return reqsize;
825
826  err_unlock:
827         spin_unlock(&fc->lock);
828         return err;
829 }
830
831 static int fuse_notify_poll(struct fuse_conn *fc, unsigned int size,
832                             struct fuse_copy_state *cs)
833 {
834         struct fuse_notify_poll_wakeup_out outarg;
835         int err = -EINVAL;
836
837         if (size != sizeof(outarg))
838                 goto err;
839
840         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
841         if (err)
842                 goto err;
843
844         fuse_copy_finish(cs);
845         return fuse_notify_poll_wakeup(fc, &outarg);
846
847 err:
848         fuse_copy_finish(cs);
849         return err;
850 }
851
852 static int fuse_notify_inval_inode(struct fuse_conn *fc, unsigned int size,
853                                    struct fuse_copy_state *cs)
854 {
855         struct fuse_notify_inval_inode_out outarg;
856         int err = -EINVAL;
857
858         if (size != sizeof(outarg))
859                 goto err;
860
861         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
862         if (err)
863                 goto err;
864         fuse_copy_finish(cs);
865
866         down_read(&fc->killsb);
867         err = -ENOENT;
868         if (!fc->sb)
869                 goto err_unlock;
870
871         err = fuse_reverse_inval_inode(fc->sb, outarg.ino,
872                                        outarg.off, outarg.len);
873
874 err_unlock:
875         up_read(&fc->killsb);
876         return err;
877
878 err:
879         fuse_copy_finish(cs);
880         return err;
881 }
882
883 static int fuse_notify_inval_entry(struct fuse_conn *fc, unsigned int size,
884                                    struct fuse_copy_state *cs)
885 {
886         struct fuse_notify_inval_entry_out outarg;
887         int err = -EINVAL;
888         char buf[FUSE_NAME_MAX+1];
889         struct qstr name;
890
891         if (size < sizeof(outarg))
892                 goto err;
893
894         err = fuse_copy_one(cs, &outarg, sizeof(outarg));
895         if (err)
896                 goto err;
897
898         err = -ENAMETOOLONG;
899         if (outarg.namelen > FUSE_NAME_MAX)
900                 goto err;
901
902         name.name = buf;
903         name.len = outarg.namelen;
904         err = fuse_copy_one(cs, buf, outarg.namelen + 1);
905         if (err)
906                 goto err;
907         fuse_copy_finish(cs);
908         buf[outarg.namelen] = 0;
909         name.hash = full_name_hash(name.name, name.len);
910
911         down_read(&fc->killsb);
912         err = -ENOENT;
913         if (!fc->sb)
914                 goto err_unlock;
915
916         err = fuse_reverse_inval_entry(fc->sb, outarg.parent, &name);
917
918 err_unlock:
919         up_read(&fc->killsb);
920         return err;
921
922 err:
923         fuse_copy_finish(cs);
924         return err;
925 }
926
927 static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
928                        unsigned int size, struct fuse_copy_state *cs)
929 {
930         switch (code) {
931         case FUSE_NOTIFY_POLL:
932                 return fuse_notify_poll(fc, size, cs);
933
934         case FUSE_NOTIFY_INVAL_INODE:
935                 return fuse_notify_inval_inode(fc, size, cs);
936
937         case FUSE_NOTIFY_INVAL_ENTRY:
938                 return fuse_notify_inval_entry(fc, size, cs);
939
940         default:
941                 fuse_copy_finish(cs);
942                 return -EINVAL;
943         }
944 }
945
946 /* Look up request on processing list by unique ID */
947 static struct fuse_req *request_find(struct fuse_conn *fc, u64 unique)
948 {
949         struct list_head *entry;
950
951         list_for_each(entry, &fc->processing) {
952                 struct fuse_req *req;
953                 req = list_entry(entry, struct fuse_req, list);
954                 if (req->in.h.unique == unique || req->intr_unique == unique)
955                         return req;
956         }
957         return NULL;
958 }
959
960 static int copy_out_args(struct fuse_copy_state *cs, struct fuse_out *out,
961                          unsigned nbytes)
962 {
963         unsigned reqsize = sizeof(struct fuse_out_header);
964
965         if (out->h.error)
966                 return nbytes != reqsize ? -EINVAL : 0;
967
968         reqsize += len_args(out->numargs, out->args);
969
970         if (reqsize < nbytes || (reqsize > nbytes && !out->argvar))
971                 return -EINVAL;
972         else if (reqsize > nbytes) {
973                 struct fuse_arg *lastarg = &out->args[out->numargs-1];
974                 unsigned diffsize = reqsize - nbytes;
975                 if (diffsize > lastarg->size)
976                         return -EINVAL;
977                 lastarg->size -= diffsize;
978         }
979         return fuse_copy_args(cs, out->numargs, out->argpages, out->args,
980                               out->page_zeroing);
981 }
982
983 /*
984  * Write a single reply to a request.  First the header is copied from
985  * the write buffer.  The request is then searched on the processing
986  * list by the unique ID found in the header.  If found, then remove
987  * it from the list and copy the rest of the buffer to the request.
988  * The request is finished by calling request_end()
989  */
990 static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov,
991                                unsigned long nr_segs, loff_t pos)
992 {
993         int err;
994         size_t nbytes = iov_length(iov, nr_segs);
995         struct fuse_req *req;
996         struct fuse_out_header oh;
997         struct fuse_copy_state cs;
998         struct fuse_conn *fc = fuse_get_conn(iocb->ki_filp);
999         if (!fc)
1000                 return -EPERM;
1001
1002         fuse_copy_init(&cs, fc, 0, NULL, iov, nr_segs);
1003         if (nbytes < sizeof(struct fuse_out_header))
1004                 return -EINVAL;
1005
1006         err = fuse_copy_one(&cs, &oh, sizeof(oh));
1007         if (err)
1008                 goto err_finish;
1009
1010         err = -EINVAL;
1011         if (oh.len != nbytes)
1012                 goto err_finish;
1013
1014         /*
1015          * Zero oh.unique indicates unsolicited notification message
1016          * and error contains notification code.
1017          */
1018         if (!oh.unique) {
1019                 err = fuse_notify(fc, oh.error, nbytes - sizeof(oh), &cs);
1020                 return err ? err : nbytes;
1021         }
1022
1023         err = -EINVAL;
1024         if (oh.error <= -1000 || oh.error > 0)
1025                 goto err_finish;
1026
1027         spin_lock(&fc->lock);
1028         err = -ENOENT;
1029         if (!fc->connected)
1030                 goto err_unlock;
1031
1032         req = request_find(fc, oh.unique);
1033         if (!req)
1034                 goto err_unlock;
1035
1036         if (req->aborted) {
1037                 spin_unlock(&fc->lock);
1038                 fuse_copy_finish(&cs);
1039                 spin_lock(&fc->lock);
1040                 request_end(fc, req);
1041                 return -ENOENT;
1042         }
1043         /* Is it an interrupt reply? */
1044         if (req->intr_unique == oh.unique) {
1045                 err = -EINVAL;
1046                 if (nbytes != sizeof(struct fuse_out_header))
1047                         goto err_unlock;
1048
1049                 if (oh.error == -ENOSYS)
1050                         fc->no_interrupt = 1;
1051                 else if (oh.error == -EAGAIN)
1052                         queue_interrupt(fc, req);
1053
1054                 spin_unlock(&fc->lock);
1055                 fuse_copy_finish(&cs);
1056                 return nbytes;
1057         }
1058
1059         req->state = FUSE_REQ_WRITING;
1060         list_move(&req->list, &fc->io);
1061         req->out.h = oh;
1062         req->locked = 1;
1063         cs.req = req;
1064         spin_unlock(&fc->lock);
1065
1066         err = copy_out_args(&cs, &req->out, nbytes);
1067         fuse_copy_finish(&cs);
1068
1069         spin_lock(&fc->lock);
1070         req->locked = 0;
1071         if (!err) {
1072                 if (req->aborted)
1073                         err = -ENOENT;
1074         } else if (!req->aborted)
1075                 req->out.h.error = -EIO;
1076         request_end(fc, req);
1077
1078         return err ? err : nbytes;
1079
1080  err_unlock:
1081         spin_unlock(&fc->lock);
1082  err_finish:
1083         fuse_copy_finish(&cs);
1084         return err;
1085 }
1086
1087 static unsigned fuse_dev_poll(struct file *file, poll_table *wait)
1088 {
1089         unsigned mask = POLLOUT | POLLWRNORM;
1090         struct fuse_conn *fc = fuse_get_conn(file);
1091         if (!fc)
1092                 return POLLERR;
1093
1094         poll_wait(file, &fc->waitq, wait);
1095
1096         spin_lock(&fc->lock);
1097         if (!fc->connected)
1098                 mask = POLLERR;
1099         else if (request_pending(fc))
1100                 mask |= POLLIN | POLLRDNORM;
1101         spin_unlock(&fc->lock);
1102
1103         return mask;
1104 }
1105
1106 /*
1107  * Abort all requests on the given list (pending or processing)
1108  *
1109  * This function releases and reacquires fc->lock
1110  */
1111 static void end_requests(struct fuse_conn *fc, struct list_head *head)
1112 __releases(&fc->lock)
1113 __acquires(&fc->lock)
1114 {
1115         while (!list_empty(head)) {
1116                 struct fuse_req *req;
1117                 req = list_entry(head->next, struct fuse_req, list);
1118                 req->out.h.error = -ECONNABORTED;
1119                 request_end(fc, req);
1120                 spin_lock(&fc->lock);
1121         }
1122 }
1123
1124 /*
1125  * Abort requests under I/O
1126  *
1127  * The requests are set to aborted and finished, and the request
1128  * waiter is woken up.  This will make request_wait_answer() wait
1129  * until the request is unlocked and then return.
1130  *
1131  * If the request is asynchronous, then the end function needs to be
1132  * called after waiting for the request to be unlocked (if it was
1133  * locked).
1134  */
1135 static void end_io_requests(struct fuse_conn *fc)
1136 __releases(&fc->lock)
1137 __acquires(&fc->lock)
1138 {
1139         while (!list_empty(&fc->io)) {
1140                 struct fuse_req *req =
1141                         list_entry(fc->io.next, struct fuse_req, list);
1142                 void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
1143
1144                 req->aborted = 1;
1145                 req->out.h.error = -ECONNABORTED;
1146                 req->state = FUSE_REQ_FINISHED;
1147                 list_del_init(&req->list);
1148                 wake_up(&req->waitq);
1149                 if (end) {
1150                         req->end = NULL;
1151                         __fuse_get_request(req);
1152                         spin_unlock(&fc->lock);
1153                         wait_event(req->waitq, !req->locked);
1154                         end(fc, req);
1155                         fuse_put_request(fc, req);
1156                         spin_lock(&fc->lock);
1157                 }
1158         }
1159 }
1160
1161 /*
1162  * Abort all requests.
1163  *
1164  * Emergency exit in case of a malicious or accidental deadlock, or
1165  * just a hung filesystem.
1166  *
1167  * The same effect is usually achievable through killing the
1168  * filesystem daemon and all users of the filesystem.  The exception
1169  * is the combination of an asynchronous request and the tricky
1170  * deadlock (see Documentation/filesystems/fuse.txt).
1171  *
1172  * During the aborting, progression of requests from the pending and
1173  * processing lists onto the io list, and progression of new requests
1174  * onto the pending list is prevented by req->connected being false.
1175  *
1176  * Progression of requests under I/O to the processing list is
1177  * prevented by the req->aborted flag being true for these requests.
1178  * For this reason requests on the io list must be aborted first.
1179  */
1180 void fuse_abort_conn(struct fuse_conn *fc)
1181 {
1182         spin_lock(&fc->lock);
1183         if (fc->connected) {
1184                 fc->connected = 0;
1185                 fc->blocked = 0;
1186                 end_io_requests(fc);
1187                 end_requests(fc, &fc->pending);
1188                 end_requests(fc, &fc->processing);
1189                 wake_up_all(&fc->waitq);
1190                 wake_up_all(&fc->blocked_waitq);
1191                 kill_fasync(&fc->fasync, SIGIO, POLL_IN);
1192         }
1193         spin_unlock(&fc->lock);
1194 }
1195 EXPORT_SYMBOL_GPL(fuse_abort_conn);
1196
1197 int fuse_dev_release(struct inode *inode, struct file *file)
1198 {
1199         struct fuse_conn *fc = fuse_get_conn(file);
1200         if (fc) {
1201                 spin_lock(&fc->lock);
1202                 fc->connected = 0;
1203                 end_requests(fc, &fc->pending);
1204                 end_requests(fc, &fc->processing);
1205                 spin_unlock(&fc->lock);
1206                 fuse_conn_put(fc);
1207         }
1208
1209         return 0;
1210 }
1211 EXPORT_SYMBOL_GPL(fuse_dev_release);
1212
1213 static int fuse_dev_fasync(int fd, struct file *file, int on)
1214 {
1215         struct fuse_conn *fc = fuse_get_conn(file);
1216         if (!fc)
1217                 return -EPERM;
1218
1219         /* No locking - fasync_helper does its own locking */
1220         return fasync_helper(fd, file, on, &fc->fasync);
1221 }
1222
1223 const struct file_operations fuse_dev_operations = {
1224         .owner          = THIS_MODULE,
1225         .llseek         = no_llseek,
1226         .read           = do_sync_read,
1227         .aio_read       = fuse_dev_read,
1228         .write          = do_sync_write,
1229         .aio_write      = fuse_dev_write,
1230         .poll           = fuse_dev_poll,
1231         .release        = fuse_dev_release,
1232         .fasync         = fuse_dev_fasync,
1233 };
1234 EXPORT_SYMBOL_GPL(fuse_dev_operations);
1235
1236 static struct miscdevice fuse_miscdevice = {
1237         .minor = FUSE_MINOR,
1238         .name  = "fuse",
1239         .fops = &fuse_dev_operations,
1240 };
1241
1242 int __init fuse_dev_init(void)
1243 {
1244         int err = -ENOMEM;
1245         fuse_req_cachep = kmem_cache_create("fuse_request",
1246                                             sizeof(struct fuse_req),
1247                                             0, 0, NULL);
1248         if (!fuse_req_cachep)
1249                 goto out;
1250
1251         err = misc_register(&fuse_miscdevice);
1252         if (err)
1253                 goto out_cache_clean;
1254
1255         return 0;
1256
1257  out_cache_clean:
1258         kmem_cache_destroy(fuse_req_cachep);
1259  out:
1260         return err;
1261 }
1262
1263 void fuse_dev_cleanup(void)
1264 {
1265         misc_deregister(&fuse_miscdevice);
1266         kmem_cache_destroy(fuse_req_cachep);
1267 }