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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394...
[linux-2.6] / fs / fuse / dev.c
1 /*
2   FUSE: Filesystem in Userspace
3   Copyright (C) 2001-2006  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
50 struct fuse_req *fuse_request_alloc_nofs(void)
51 {
52         struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, GFP_NOFS);
53         if (req)
54                 fuse_request_init(req);
55         return req;
56 }
57
58 void fuse_request_free(struct fuse_req *req)
59 {
60         kmem_cache_free(fuse_req_cachep, req);
61 }
62
63 static void block_sigs(sigset_t *oldset)
64 {
65         sigset_t mask;
66
67         siginitsetinv(&mask, sigmask(SIGKILL));
68         sigprocmask(SIG_BLOCK, &mask, oldset);
69 }
70
71 static void restore_sigs(sigset_t *oldset)
72 {
73         sigprocmask(SIG_SETMASK, oldset, NULL);
74 }
75
76 static void __fuse_get_request(struct fuse_req *req)
77 {
78         atomic_inc(&req->count);
79 }
80
81 /* Must be called with > 1 refcount */
82 static void __fuse_put_request(struct fuse_req *req)
83 {
84         BUG_ON(atomic_read(&req->count) < 2);
85         atomic_dec(&req->count);
86 }
87
88 static void fuse_req_init_context(struct fuse_req *req)
89 {
90         req->in.h.uid = current->fsuid;
91         req->in.h.gid = current->fsgid;
92         req->in.h.pid = current->pid;
93 }
94
95 struct fuse_req *fuse_get_req(struct fuse_conn *fc)
96 {
97         struct fuse_req *req;
98         sigset_t oldset;
99         int intr;
100         int err;
101
102         atomic_inc(&fc->num_waiting);
103         block_sigs(&oldset);
104         intr = wait_event_interruptible(fc->blocked_waitq, !fc->blocked);
105         restore_sigs(&oldset);
106         err = -EINTR;
107         if (intr)
108                 goto out;
109
110         err = -ENOTCONN;
111         if (!fc->connected)
112                 goto out;
113
114         req = fuse_request_alloc();
115         err = -ENOMEM;
116         if (!req)
117                 goto out;
118
119         fuse_req_init_context(req);
120         req->waiting = 1;
121         return req;
122
123  out:
124         atomic_dec(&fc->num_waiting);
125         return ERR_PTR(err);
126 }
127
128 /*
129  * Return request in fuse_file->reserved_req.  However that may
130  * currently be in use.  If that is the case, wait for it to become
131  * available.
132  */
133 static struct fuse_req *get_reserved_req(struct fuse_conn *fc,
134                                          struct file *file)
135 {
136         struct fuse_req *req = NULL;
137         struct fuse_file *ff = file->private_data;
138
139         do {
140                 wait_event(fc->reserved_req_waitq, ff->reserved_req);
141                 spin_lock(&fc->lock);
142                 if (ff->reserved_req) {
143                         req = ff->reserved_req;
144                         ff->reserved_req = NULL;
145                         get_file(file);
146                         req->stolen_file = file;
147                 }
148                 spin_unlock(&fc->lock);
149         } while (!req);
150
151         return req;
152 }
153
154 /*
155  * Put stolen request back into fuse_file->reserved_req
156  */
157 static void put_reserved_req(struct fuse_conn *fc, struct fuse_req *req)
158 {
159         struct file *file = req->stolen_file;
160         struct fuse_file *ff = file->private_data;
161
162         spin_lock(&fc->lock);
163         fuse_request_init(req);
164         BUG_ON(ff->reserved_req);
165         ff->reserved_req = req;
166         wake_up_all(&fc->reserved_req_waitq);
167         spin_unlock(&fc->lock);
168         fput(file);
169 }
170
171 /*
172  * Gets a requests for a file operation, always succeeds
173  *
174  * This is used for sending the FLUSH request, which must get to
175  * userspace, due to POSIX locks which may need to be unlocked.
176  *
177  * If allocation fails due to OOM, use the reserved request in
178  * fuse_file.
179  *
180  * This is very unlikely to deadlock accidentally, since the
181  * filesystem should not have it's own file open.  If deadlock is
182  * intentional, it can still be broken by "aborting" the filesystem.
183  */
184 struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file)
185 {
186         struct fuse_req *req;
187
188         atomic_inc(&fc->num_waiting);
189         wait_event(fc->blocked_waitq, !fc->blocked);
190         req = fuse_request_alloc();
191         if (!req)
192                 req = get_reserved_req(fc, file);
193
194         fuse_req_init_context(req);
195         req->waiting = 1;
196         return req;
197 }
198
199 void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
200 {
201         if (atomic_dec_and_test(&req->count)) {
202                 if (req->waiting)
203                         atomic_dec(&fc->num_waiting);
204
205                 if (req->stolen_file)
206                         put_reserved_req(fc, req);
207                 else
208                         fuse_request_free(req);
209         }
210 }
211
212 static unsigned len_args(unsigned numargs, struct fuse_arg *args)
213 {
214         unsigned nbytes = 0;
215         unsigned i;
216
217         for (i = 0; i < numargs; i++)
218                 nbytes += args[i].size;
219
220         return nbytes;
221 }
222
223 static u64 fuse_get_unique(struct fuse_conn *fc)
224 {
225         fc->reqctr++;
226         /* zero is special */
227         if (fc->reqctr == 0)
228                 fc->reqctr = 1;
229
230         return fc->reqctr;
231 }
232
233 static void queue_request(struct fuse_conn *fc, struct fuse_req *req)
234 {
235         req->in.h.unique = fuse_get_unique(fc);
236         req->in.h.len = sizeof(struct fuse_in_header) +
237                 len_args(req->in.numargs, (struct fuse_arg *) req->in.args);
238         list_add_tail(&req->list, &fc->pending);
239         req->state = FUSE_REQ_PENDING;
240         if (!req->waiting) {
241                 req->waiting = 1;
242                 atomic_inc(&fc->num_waiting);
243         }
244         wake_up(&fc->waitq);
245         kill_fasync(&fc->fasync, SIGIO, POLL_IN);
246 }
247
248 static void flush_bg_queue(struct fuse_conn *fc)
249 {
250         while (fc->active_background < FUSE_MAX_BACKGROUND &&
251                !list_empty(&fc->bg_queue)) {
252                 struct fuse_req *req;
253
254                 req = list_entry(fc->bg_queue.next, struct fuse_req, list);
255                 list_del(&req->list);
256                 fc->active_background++;
257                 queue_request(fc, req);
258         }
259 }
260
261 /*
262  * This function is called when a request is finished.  Either a reply
263  * has arrived or it was aborted (and not yet sent) or some error
264  * occurred during communication with userspace, or the device file
265  * was closed.  The requester thread is woken up (if still waiting),
266  * the 'end' callback is called if given, else the reference to the
267  * request is released
268  *
269  * Called with fc->lock, unlocks it
270  */
271 static void request_end(struct fuse_conn *fc, struct fuse_req *req)
272         __releases(fc->lock)
273 {
274         void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
275         req->end = NULL;
276         list_del(&req->list);
277         list_del(&req->intr_entry);
278         req->state = FUSE_REQ_FINISHED;
279         if (req->background) {
280                 if (fc->num_background == FUSE_MAX_BACKGROUND) {
281                         fc->blocked = 0;
282                         wake_up_all(&fc->blocked_waitq);
283                 }
284                 if (fc->num_background == FUSE_CONGESTION_THRESHOLD) {
285                         clear_bdi_congested(&fc->bdi, READ);
286                         clear_bdi_congested(&fc->bdi, WRITE);
287                 }
288                 fc->num_background--;
289                 fc->active_background--;
290                 flush_bg_queue(fc);
291         }
292         spin_unlock(&fc->lock);
293         wake_up(&req->waitq);
294         if (end)
295                 end(fc, req);
296         else
297                 fuse_put_request(fc, req);
298 }
299
300 static void wait_answer_interruptible(struct fuse_conn *fc,
301                                       struct fuse_req *req)
302         __releases(fc->lock) __acquires(fc->lock)
303 {
304         if (signal_pending(current))
305                 return;
306
307         spin_unlock(&fc->lock);
308         wait_event_interruptible(req->waitq, req->state == FUSE_REQ_FINISHED);
309         spin_lock(&fc->lock);
310 }
311
312 static void queue_interrupt(struct fuse_conn *fc, struct fuse_req *req)
313 {
314         list_add_tail(&req->intr_entry, &fc->interrupts);
315         wake_up(&fc->waitq);
316         kill_fasync(&fc->fasync, SIGIO, POLL_IN);
317 }
318
319 static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
320         __releases(fc->lock) __acquires(fc->lock)
321 {
322         if (!fc->no_interrupt) {
323                 /* Any signal may interrupt this */
324                 wait_answer_interruptible(fc, req);
325
326                 if (req->aborted)
327                         goto aborted;
328                 if (req->state == FUSE_REQ_FINISHED)
329                         return;
330
331                 req->interrupted = 1;
332                 if (req->state == FUSE_REQ_SENT)
333                         queue_interrupt(fc, req);
334         }
335
336         if (!req->force) {
337                 sigset_t oldset;
338
339                 /* Only fatal signals may interrupt this */
340                 block_sigs(&oldset);
341                 wait_answer_interruptible(fc, req);
342                 restore_sigs(&oldset);
343
344                 if (req->aborted)
345                         goto aborted;
346                 if (req->state == FUSE_REQ_FINISHED)
347                         return;
348
349                 /* Request is not yet in userspace, bail out */
350                 if (req->state == FUSE_REQ_PENDING) {
351                         list_del(&req->list);
352                         __fuse_put_request(req);
353                         req->out.h.error = -EINTR;
354                         return;
355                 }
356         }
357
358         /*
359          * Either request is already in userspace, or it was forced.
360          * Wait it out.
361          */
362         spin_unlock(&fc->lock);
363         wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
364         spin_lock(&fc->lock);
365
366         if (!req->aborted)
367                 return;
368
369  aborted:
370         BUG_ON(req->state != FUSE_REQ_FINISHED);
371         if (req->locked) {
372                 /* This is uninterruptible sleep, because data is
373                    being copied to/from the buffers of req.  During
374                    locked state, there mustn't be any filesystem
375                    operation (e.g. page fault), since that could lead
376                    to deadlock */
377                 spin_unlock(&fc->lock);
378                 wait_event(req->waitq, !req->locked);
379                 spin_lock(&fc->lock);
380         }
381 }
382
383 void request_send(struct fuse_conn *fc, struct fuse_req *req)
384 {
385         req->isreply = 1;
386         spin_lock(&fc->lock);
387         if (!fc->connected)
388                 req->out.h.error = -ENOTCONN;
389         else if (fc->conn_error)
390                 req->out.h.error = -ECONNREFUSED;
391         else {
392                 queue_request(fc, req);
393                 /* acquire extra reference, since request is still needed
394                    after request_end() */
395                 __fuse_get_request(req);
396
397                 request_wait_answer(fc, req);
398         }
399         spin_unlock(&fc->lock);
400 }
401
402 static void request_send_nowait_locked(struct fuse_conn *fc,
403                                        struct fuse_req *req)
404 {
405         req->background = 1;
406         fc->num_background++;
407         if (fc->num_background == FUSE_MAX_BACKGROUND)
408                 fc->blocked = 1;
409         if (fc->num_background == FUSE_CONGESTION_THRESHOLD) {
410                 set_bdi_congested(&fc->bdi, READ);
411                 set_bdi_congested(&fc->bdi, WRITE);
412         }
413         list_add_tail(&req->list, &fc->bg_queue);
414         flush_bg_queue(fc);
415 }
416
417 static void request_send_nowait(struct fuse_conn *fc, struct fuse_req *req)
418 {
419         spin_lock(&fc->lock);
420         if (fc->connected) {
421                 request_send_nowait_locked(fc, req);
422                 spin_unlock(&fc->lock);
423         } else {
424                 req->out.h.error = -ENOTCONN;
425                 request_end(fc, req);
426         }
427 }
428
429 void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req)
430 {
431         req->isreply = 0;
432         request_send_nowait(fc, req);
433 }
434
435 void request_send_background(struct fuse_conn *fc, struct fuse_req *req)
436 {
437         req->isreply = 1;
438         request_send_nowait(fc, req);
439 }
440
441 /*
442  * Called under fc->lock
443  *
444  * fc->connected must have been checked previously
445  */
446 void request_send_background_locked(struct fuse_conn *fc, struct fuse_req *req)
447 {
448         req->isreply = 1;
449         request_send_nowait_locked(fc, req);
450 }
451
452 /*
453  * Lock the request.  Up to the next unlock_request() there mustn't be
454  * anything that could cause a page-fault.  If the request was already
455  * aborted bail out.
456  */
457 static int lock_request(struct fuse_conn *fc, struct fuse_req *req)
458 {
459         int err = 0;
460         if (req) {
461                 spin_lock(&fc->lock);
462                 if (req->aborted)
463                         err = -ENOENT;
464                 else
465                         req->locked = 1;
466                 spin_unlock(&fc->lock);
467         }
468         return err;
469 }
470
471 /*
472  * Unlock request.  If it was aborted during being locked, the
473  * requester thread is currently waiting for it to be unlocked, so
474  * wake it up.
475  */
476 static void unlock_request(struct fuse_conn *fc, struct fuse_req *req)
477 {
478         if (req) {
479                 spin_lock(&fc->lock);
480                 req->locked = 0;
481                 if (req->aborted)
482                         wake_up(&req->waitq);
483                 spin_unlock(&fc->lock);
484         }
485 }
486
487 struct fuse_copy_state {
488         struct fuse_conn *fc;
489         int write;
490         struct fuse_req *req;
491         const struct iovec *iov;
492         unsigned long nr_segs;
493         unsigned long seglen;
494         unsigned long addr;
495         struct page *pg;
496         void *mapaddr;
497         void *buf;
498         unsigned len;
499 };
500
501 static void fuse_copy_init(struct fuse_copy_state *cs, struct fuse_conn *fc,
502                            int write, struct fuse_req *req,
503                            const struct iovec *iov, unsigned long nr_segs)
504 {
505         memset(cs, 0, sizeof(*cs));
506         cs->fc = fc;
507         cs->write = write;
508         cs->req = req;
509         cs->iov = iov;
510         cs->nr_segs = nr_segs;
511 }
512
513 /* Unmap and put previous page of userspace buffer */
514 static void fuse_copy_finish(struct fuse_copy_state *cs)
515 {
516         if (cs->mapaddr) {
517                 kunmap_atomic(cs->mapaddr, KM_USER0);
518                 if (cs->write) {
519                         flush_dcache_page(cs->pg);
520                         set_page_dirty_lock(cs->pg);
521                 }
522                 put_page(cs->pg);
523                 cs->mapaddr = NULL;
524         }
525 }
526
527 /*
528  * Get another pagefull of userspace buffer, and map it to kernel
529  * address space, and lock request
530  */
531 static int fuse_copy_fill(struct fuse_copy_state *cs)
532 {
533         unsigned long offset;
534         int err;
535
536         unlock_request(cs->fc, cs->req);
537         fuse_copy_finish(cs);
538         if (!cs->seglen) {
539                 BUG_ON(!cs->nr_segs);
540                 cs->seglen = cs->iov[0].iov_len;
541                 cs->addr = (unsigned long) cs->iov[0].iov_base;
542                 cs->iov ++;
543                 cs->nr_segs --;
544         }
545         down_read(&current->mm->mmap_sem);
546         err = get_user_pages(current, current->mm, cs->addr, 1, cs->write, 0,
547                              &cs->pg, NULL);
548         up_read(&current->mm->mmap_sem);
549         if (err < 0)
550                 return err;
551         BUG_ON(err != 1);
552         offset = cs->addr % PAGE_SIZE;
553         cs->mapaddr = kmap_atomic(cs->pg, KM_USER0);
554         cs->buf = cs->mapaddr + offset;
555         cs->len = min(PAGE_SIZE - offset, cs->seglen);
556         cs->seglen -= cs->len;
557         cs->addr += cs->len;
558
559         return lock_request(cs->fc, cs->req);
560 }
561
562 /* Do as much copy to/from userspace buffer as we can */
563 static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
564 {
565         unsigned ncpy = min(*size, cs->len);
566         if (val) {
567                 if (cs->write)
568                         memcpy(cs->buf, *val, ncpy);
569                 else
570                         memcpy(*val, cs->buf, ncpy);
571                 *val += ncpy;
572         }
573         *size -= ncpy;
574         cs->len -= ncpy;
575         cs->buf += ncpy;
576         return ncpy;
577 }
578
579 /*
580  * Copy a page in the request to/from the userspace buffer.  Must be
581  * done atomically
582  */
583 static int fuse_copy_page(struct fuse_copy_state *cs, struct page *page,
584                           unsigned offset, unsigned count, int zeroing)
585 {
586         if (page && zeroing && count < PAGE_SIZE) {
587                 void *mapaddr = kmap_atomic(page, KM_USER1);
588                 memset(mapaddr, 0, PAGE_SIZE);
589                 kunmap_atomic(mapaddr, KM_USER1);
590         }
591         while (count) {
592                 int err;
593                 if (!cs->len && (err = fuse_copy_fill(cs)))
594                         return err;
595                 if (page) {
596                         void *mapaddr = kmap_atomic(page, KM_USER1);
597                         void *buf = mapaddr + offset;
598                         offset += fuse_copy_do(cs, &buf, &count);
599                         kunmap_atomic(mapaddr, KM_USER1);
600                 } else
601                         offset += fuse_copy_do(cs, NULL, &count);
602         }
603         if (page && !cs->write)
604                 flush_dcache_page(page);
605         return 0;
606 }
607
608 /* Copy pages in the request to/from userspace buffer */
609 static int fuse_copy_pages(struct fuse_copy_state *cs, unsigned nbytes,
610                            int zeroing)
611 {
612         unsigned i;
613         struct fuse_req *req = cs->req;
614         unsigned offset = req->page_offset;
615         unsigned count = min(nbytes, (unsigned) PAGE_SIZE - offset);
616
617         for (i = 0; i < req->num_pages && (nbytes || zeroing); i++) {
618                 struct page *page = req->pages[i];
619                 int err = fuse_copy_page(cs, page, offset, count, zeroing);
620                 if (err)
621                         return err;
622
623                 nbytes -= count;
624                 count = min(nbytes, (unsigned) PAGE_SIZE);
625                 offset = 0;
626         }
627         return 0;
628 }
629
630 /* Copy a single argument in the request to/from userspace buffer */
631 static int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned size)
632 {
633         while (size) {
634                 int err;
635                 if (!cs->len && (err = fuse_copy_fill(cs)))
636                         return err;
637                 fuse_copy_do(cs, &val, &size);
638         }
639         return 0;
640 }
641
642 /* Copy request arguments to/from userspace buffer */
643 static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs,
644                           unsigned argpages, struct fuse_arg *args,
645                           int zeroing)
646 {
647         int err = 0;
648         unsigned i;
649
650         for (i = 0; !err && i < numargs; i++)  {
651                 struct fuse_arg *arg = &args[i];
652                 if (i == numargs - 1 && argpages)
653                         err = fuse_copy_pages(cs, arg->size, zeroing);
654                 else
655                         err = fuse_copy_one(cs, arg->value, arg->size);
656         }
657         return err;
658 }
659
660 static int request_pending(struct fuse_conn *fc)
661 {
662         return !list_empty(&fc->pending) || !list_empty(&fc->interrupts);
663 }
664
665 /* Wait until a request is available on the pending list */
666 static void request_wait(struct fuse_conn *fc)
667 {
668         DECLARE_WAITQUEUE(wait, current);
669
670         add_wait_queue_exclusive(&fc->waitq, &wait);
671         while (fc->connected && !request_pending(fc)) {
672                 set_current_state(TASK_INTERRUPTIBLE);
673                 if (signal_pending(current))
674                         break;
675
676                 spin_unlock(&fc->lock);
677                 schedule();
678                 spin_lock(&fc->lock);
679         }
680         set_current_state(TASK_RUNNING);
681         remove_wait_queue(&fc->waitq, &wait);
682 }
683
684 /*
685  * Transfer an interrupt request to userspace
686  *
687  * Unlike other requests this is assembled on demand, without a need
688  * to allocate a separate fuse_req structure.
689  *
690  * Called with fc->lock held, releases it
691  */
692 static int fuse_read_interrupt(struct fuse_conn *fc, struct fuse_req *req,
693                                const struct iovec *iov, unsigned long nr_segs)
694         __releases(fc->lock)
695 {
696         struct fuse_copy_state cs;
697         struct fuse_in_header ih;
698         struct fuse_interrupt_in arg;
699         unsigned reqsize = sizeof(ih) + sizeof(arg);
700         int err;
701
702         list_del_init(&req->intr_entry);
703         req->intr_unique = fuse_get_unique(fc);
704         memset(&ih, 0, sizeof(ih));
705         memset(&arg, 0, sizeof(arg));
706         ih.len = reqsize;
707         ih.opcode = FUSE_INTERRUPT;
708         ih.unique = req->intr_unique;
709         arg.unique = req->in.h.unique;
710
711         spin_unlock(&fc->lock);
712         if (iov_length(iov, nr_segs) < reqsize)
713                 return -EINVAL;
714
715         fuse_copy_init(&cs, fc, 1, NULL, iov, nr_segs);
716         err = fuse_copy_one(&cs, &ih, sizeof(ih));
717         if (!err)
718                 err = fuse_copy_one(&cs, &arg, sizeof(arg));
719         fuse_copy_finish(&cs);
720
721         return err ? err : reqsize;
722 }
723
724 /*
725  * Read a single request into the userspace filesystem's buffer.  This
726  * function waits until a request is available, then removes it from
727  * the pending list and copies request data to userspace buffer.  If
728  * no reply is needed (FORGET) or request has been aborted or there
729  * was an error during the copying then it's finished by calling
730  * request_end().  Otherwise add it to the processing list, and set
731  * the 'sent' flag.
732  */
733 static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
734                               unsigned long nr_segs, loff_t pos)
735 {
736         int err;
737         struct fuse_req *req;
738         struct fuse_in *in;
739         struct fuse_copy_state cs;
740         unsigned reqsize;
741         struct file *file = iocb->ki_filp;
742         struct fuse_conn *fc = fuse_get_conn(file);
743         if (!fc)
744                 return -EPERM;
745
746  restart:
747         spin_lock(&fc->lock);
748         err = -EAGAIN;
749         if ((file->f_flags & O_NONBLOCK) && fc->connected &&
750             !request_pending(fc))
751                 goto err_unlock;
752
753         request_wait(fc);
754         err = -ENODEV;
755         if (!fc->connected)
756                 goto err_unlock;
757         err = -ERESTARTSYS;
758         if (!request_pending(fc))
759                 goto err_unlock;
760
761         if (!list_empty(&fc->interrupts)) {
762                 req = list_entry(fc->interrupts.next, struct fuse_req,
763                                  intr_entry);
764                 return fuse_read_interrupt(fc, req, iov, nr_segs);
765         }
766
767         req = list_entry(fc->pending.next, struct fuse_req, list);
768         req->state = FUSE_REQ_READING;
769         list_move(&req->list, &fc->io);
770
771         in = &req->in;
772         reqsize = in->h.len;
773         /* If request is too large, reply with an error and restart the read */
774         if (iov_length(iov, nr_segs) < reqsize) {
775                 req->out.h.error = -EIO;
776                 /* SETXATTR is special, since it may contain too large data */
777                 if (in->h.opcode == FUSE_SETXATTR)
778                         req->out.h.error = -E2BIG;
779                 request_end(fc, req);
780                 goto restart;
781         }
782         spin_unlock(&fc->lock);
783         fuse_copy_init(&cs, fc, 1, req, iov, nr_segs);
784         err = fuse_copy_one(&cs, &in->h, sizeof(in->h));
785         if (!err)
786                 err = fuse_copy_args(&cs, in->numargs, in->argpages,
787                                      (struct fuse_arg *) in->args, 0);
788         fuse_copy_finish(&cs);
789         spin_lock(&fc->lock);
790         req->locked = 0;
791         if (req->aborted) {
792                 request_end(fc, req);
793                 return -ENODEV;
794         }
795         if (err) {
796                 req->out.h.error = -EIO;
797                 request_end(fc, req);
798                 return err;
799         }
800         if (!req->isreply)
801                 request_end(fc, req);
802         else {
803                 req->state = FUSE_REQ_SENT;
804                 list_move_tail(&req->list, &fc->processing);
805                 if (req->interrupted)
806                         queue_interrupt(fc, req);
807                 spin_unlock(&fc->lock);
808         }
809         return reqsize;
810
811  err_unlock:
812         spin_unlock(&fc->lock);
813         return err;
814 }
815
816 /* Look up request on processing list by unique ID */
817 static struct fuse_req *request_find(struct fuse_conn *fc, u64 unique)
818 {
819         struct list_head *entry;
820
821         list_for_each(entry, &fc->processing) {
822                 struct fuse_req *req;
823                 req = list_entry(entry, struct fuse_req, list);
824                 if (req->in.h.unique == unique || req->intr_unique == unique)
825                         return req;
826         }
827         return NULL;
828 }
829
830 static int copy_out_args(struct fuse_copy_state *cs, struct fuse_out *out,
831                          unsigned nbytes)
832 {
833         unsigned reqsize = sizeof(struct fuse_out_header);
834
835         if (out->h.error)
836                 return nbytes != reqsize ? -EINVAL : 0;
837
838         reqsize += len_args(out->numargs, out->args);
839
840         if (reqsize < nbytes || (reqsize > nbytes && !out->argvar))
841                 return -EINVAL;
842         else if (reqsize > nbytes) {
843                 struct fuse_arg *lastarg = &out->args[out->numargs-1];
844                 unsigned diffsize = reqsize - nbytes;
845                 if (diffsize > lastarg->size)
846                         return -EINVAL;
847                 lastarg->size -= diffsize;
848         }
849         return fuse_copy_args(cs, out->numargs, out->argpages, out->args,
850                               out->page_zeroing);
851 }
852
853 /*
854  * Write a single reply to a request.  First the header is copied from
855  * the write buffer.  The request is then searched on the processing
856  * list by the unique ID found in the header.  If found, then remove
857  * it from the list and copy the rest of the buffer to the request.
858  * The request is finished by calling request_end()
859  */
860 static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov,
861                                unsigned long nr_segs, loff_t pos)
862 {
863         int err;
864         unsigned nbytes = iov_length(iov, nr_segs);
865         struct fuse_req *req;
866         struct fuse_out_header oh;
867         struct fuse_copy_state cs;
868         struct fuse_conn *fc = fuse_get_conn(iocb->ki_filp);
869         if (!fc)
870                 return -EPERM;
871
872         fuse_copy_init(&cs, fc, 0, NULL, iov, nr_segs);
873         if (nbytes < sizeof(struct fuse_out_header))
874                 return -EINVAL;
875
876         err = fuse_copy_one(&cs, &oh, sizeof(oh));
877         if (err)
878                 goto err_finish;
879         err = -EINVAL;
880         if (!oh.unique || oh.error <= -1000 || oh.error > 0 ||
881             oh.len != nbytes)
882                 goto err_finish;
883
884         spin_lock(&fc->lock);
885         err = -ENOENT;
886         if (!fc->connected)
887                 goto err_unlock;
888
889         req = request_find(fc, oh.unique);
890         if (!req)
891                 goto err_unlock;
892
893         if (req->aborted) {
894                 spin_unlock(&fc->lock);
895                 fuse_copy_finish(&cs);
896                 spin_lock(&fc->lock);
897                 request_end(fc, req);
898                 return -ENOENT;
899         }
900         /* Is it an interrupt reply? */
901         if (req->intr_unique == oh.unique) {
902                 err = -EINVAL;
903                 if (nbytes != sizeof(struct fuse_out_header))
904                         goto err_unlock;
905
906                 if (oh.error == -ENOSYS)
907                         fc->no_interrupt = 1;
908                 else if (oh.error == -EAGAIN)
909                         queue_interrupt(fc, req);
910
911                 spin_unlock(&fc->lock);
912                 fuse_copy_finish(&cs);
913                 return nbytes;
914         }
915
916         req->state = FUSE_REQ_WRITING;
917         list_move(&req->list, &fc->io);
918         req->out.h = oh;
919         req->locked = 1;
920         cs.req = req;
921         spin_unlock(&fc->lock);
922
923         err = copy_out_args(&cs, &req->out, nbytes);
924         fuse_copy_finish(&cs);
925
926         spin_lock(&fc->lock);
927         req->locked = 0;
928         if (!err) {
929                 if (req->aborted)
930                         err = -ENOENT;
931         } else if (!req->aborted)
932                 req->out.h.error = -EIO;
933         request_end(fc, req);
934
935         return err ? err : nbytes;
936
937  err_unlock:
938         spin_unlock(&fc->lock);
939  err_finish:
940         fuse_copy_finish(&cs);
941         return err;
942 }
943
944 static unsigned fuse_dev_poll(struct file *file, poll_table *wait)
945 {
946         unsigned mask = POLLOUT | POLLWRNORM;
947         struct fuse_conn *fc = fuse_get_conn(file);
948         if (!fc)
949                 return POLLERR;
950
951         poll_wait(file, &fc->waitq, wait);
952
953         spin_lock(&fc->lock);
954         if (!fc->connected)
955                 mask = POLLERR;
956         else if (request_pending(fc))
957                 mask |= POLLIN | POLLRDNORM;
958         spin_unlock(&fc->lock);
959
960         return mask;
961 }
962
963 /*
964  * Abort all requests on the given list (pending or processing)
965  *
966  * This function releases and reacquires fc->lock
967  */
968 static void end_requests(struct fuse_conn *fc, struct list_head *head)
969 {
970         while (!list_empty(head)) {
971                 struct fuse_req *req;
972                 req = list_entry(head->next, struct fuse_req, list);
973                 req->out.h.error = -ECONNABORTED;
974                 request_end(fc, req);
975                 spin_lock(&fc->lock);
976         }
977 }
978
979 /*
980  * Abort requests under I/O
981  *
982  * The requests are set to aborted and finished, and the request
983  * waiter is woken up.  This will make request_wait_answer() wait
984  * until the request is unlocked and then return.
985  *
986  * If the request is asynchronous, then the end function needs to be
987  * called after waiting for the request to be unlocked (if it was
988  * locked).
989  */
990 static void end_io_requests(struct fuse_conn *fc)
991         __releases(fc->lock) __acquires(fc->lock)
992 {
993         while (!list_empty(&fc->io)) {
994                 struct fuse_req *req =
995                         list_entry(fc->io.next, struct fuse_req, list);
996                 void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
997
998                 req->aborted = 1;
999                 req->out.h.error = -ECONNABORTED;
1000                 req->state = FUSE_REQ_FINISHED;
1001                 list_del_init(&req->list);
1002                 wake_up(&req->waitq);
1003                 if (end) {
1004                         req->end = NULL;
1005                         /* The end function will consume this reference */
1006                         __fuse_get_request(req);
1007                         spin_unlock(&fc->lock);
1008                         wait_event(req->waitq, !req->locked);
1009                         end(fc, req);
1010                         spin_lock(&fc->lock);
1011                 }
1012         }
1013 }
1014
1015 /*
1016  * Abort all requests.
1017  *
1018  * Emergency exit in case of a malicious or accidental deadlock, or
1019  * just a hung filesystem.
1020  *
1021  * The same effect is usually achievable through killing the
1022  * filesystem daemon and all users of the filesystem.  The exception
1023  * is the combination of an asynchronous request and the tricky
1024  * deadlock (see Documentation/filesystems/fuse.txt).
1025  *
1026  * During the aborting, progression of requests from the pending and
1027  * processing lists onto the io list, and progression of new requests
1028  * onto the pending list is prevented by req->connected being false.
1029  *
1030  * Progression of requests under I/O to the processing list is
1031  * prevented by the req->aborted flag being true for these requests.
1032  * For this reason requests on the io list must be aborted first.
1033  */
1034 void fuse_abort_conn(struct fuse_conn *fc)
1035 {
1036         spin_lock(&fc->lock);
1037         if (fc->connected) {
1038                 fc->connected = 0;
1039                 fc->blocked = 0;
1040                 end_io_requests(fc);
1041                 end_requests(fc, &fc->pending);
1042                 end_requests(fc, &fc->processing);
1043                 wake_up_all(&fc->waitq);
1044                 wake_up_all(&fc->blocked_waitq);
1045                 kill_fasync(&fc->fasync, SIGIO, POLL_IN);
1046         }
1047         spin_unlock(&fc->lock);
1048 }
1049
1050 static int fuse_dev_release(struct inode *inode, struct file *file)
1051 {
1052         struct fuse_conn *fc = fuse_get_conn(file);
1053         if (fc) {
1054                 spin_lock(&fc->lock);
1055                 fc->connected = 0;
1056                 end_requests(fc, &fc->pending);
1057                 end_requests(fc, &fc->processing);
1058                 spin_unlock(&fc->lock);
1059                 fasync_helper(-1, file, 0, &fc->fasync);
1060                 fuse_conn_put(fc);
1061         }
1062
1063         return 0;
1064 }
1065
1066 static int fuse_dev_fasync(int fd, struct file *file, int on)
1067 {
1068         struct fuse_conn *fc = fuse_get_conn(file);
1069         if (!fc)
1070                 return -EPERM;
1071
1072         /* No locking - fasync_helper does its own locking */
1073         return fasync_helper(fd, file, on, &fc->fasync);
1074 }
1075
1076 const struct file_operations fuse_dev_operations = {
1077         .owner          = THIS_MODULE,
1078         .llseek         = no_llseek,
1079         .read           = do_sync_read,
1080         .aio_read       = fuse_dev_read,
1081         .write          = do_sync_write,
1082         .aio_write      = fuse_dev_write,
1083         .poll           = fuse_dev_poll,
1084         .release        = fuse_dev_release,
1085         .fasync         = fuse_dev_fasync,
1086 };
1087
1088 static struct miscdevice fuse_miscdevice = {
1089         .minor = FUSE_MINOR,
1090         .name  = "fuse",
1091         .fops = &fuse_dev_operations,
1092 };
1093
1094 int __init fuse_dev_init(void)
1095 {
1096         int err = -ENOMEM;
1097         fuse_req_cachep = kmem_cache_create("fuse_request",
1098                                             sizeof(struct fuse_req),
1099                                             0, 0, NULL);
1100         if (!fuse_req_cachep)
1101                 goto out;
1102
1103         err = misc_register(&fuse_miscdevice);
1104         if (err)
1105                 goto out_cache_clean;
1106
1107         return 0;
1108
1109  out_cache_clean:
1110         kmem_cache_destroy(fuse_req_cachep);
1111  out:
1112         return err;
1113 }
1114
1115 void fuse_dev_cleanup(void)
1116 {
1117         misc_deregister(&fuse_miscdevice);
1118         kmem_cache_destroy(fuse_req_cachep);
1119 }