dev.c 25.1 KB
Newer Older
1
2
/*
  FUSE: Filesystem in Userspace
3
  Copyright (C) 2001-2006  Miklos Szeredi <miklos@szeredi.hu>
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21

  This program can be distributed under the terms of the GNU GPL.
  See the file COPYING.
*/

#include "fuse_i.h"

#include <linux/init.h>
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/uio.h>
#include <linux/miscdevice.h>
#include <linux/pagemap.h>
#include <linux/file.h>
#include <linux/slab.h>

MODULE_ALIAS_MISCDEV(FUSE_MINOR);

22
static struct kmem_cache *fuse_req_cachep;
23

24
static struct fuse_conn *fuse_get_conn(struct file *file)
25
{
26
27
28
29
30
	/*
	 * Lockless access is OK, because file->private data is set
	 * once during mount and is valid until the file is released.
	 */
	return file->private_data;
31
32
}

33
static void fuse_request_init(struct fuse_req *req)
34
35
36
{
	memset(req, 0, sizeof(*req));
	INIT_LIST_HEAD(&req->list);
37
	INIT_LIST_HEAD(&req->intr_entry);
38
39
40
41
42
43
	init_waitqueue_head(&req->waitq);
	atomic_set(&req->count, 1);
}

struct fuse_req *fuse_request_alloc(void)
{
44
	struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, GFP_KERNEL);
45
46
47
48
49
50
51
52
53
54
	if (req)
		fuse_request_init(req);
	return req;
}

void fuse_request_free(struct fuse_req *req)
{
	kmem_cache_free(fuse_req_cachep, req);
}

55
static void block_sigs(sigset_t *oldset)
56
57
58
59
60
61
62
{
	sigset_t mask;

	siginitsetinv(&mask, sigmask(SIGKILL));
	sigprocmask(SIG_BLOCK, &mask, oldset);
}

63
static void restore_sigs(sigset_t *oldset)
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
{
	sigprocmask(SIG_SETMASK, oldset, NULL);
}

static void __fuse_get_request(struct fuse_req *req)
{
	atomic_inc(&req->count);
}

/* Must be called with > 1 refcount */
static void __fuse_put_request(struct fuse_req *req)
{
	BUG_ON(atomic_read(&req->count) < 2);
	atomic_dec(&req->count);
}

80
81
82
83
84
85
86
static void fuse_req_init_context(struct fuse_req *req)
{
	req->in.h.uid = current->fsuid;
	req->in.h.gid = current->fsgid;
	req->in.h.pid = current->pid;
}

87
struct fuse_req *fuse_get_req(struct fuse_conn *fc)
88
{
89
90
	struct fuse_req *req;
	sigset_t oldset;
91
	int intr;
92
93
	int err;

94
	atomic_inc(&fc->num_waiting);
95
	block_sigs(&oldset);
96
	intr = wait_event_interruptible(fc->blocked_waitq, !fc->blocked);
97
	restore_sigs(&oldset);
98
99
100
	err = -EINTR;
	if (intr)
		goto out;
101

102
103
104
105
	err = -ENOTCONN;
	if (!fc->connected)
		goto out;

106
	req = fuse_request_alloc();
107
	err = -ENOMEM;
108
	if (!req)
109
		goto out;
110

111
	fuse_req_init_context(req);
112
	req->waiting = 1;
113
	return req;
114
115
116
117

 out:
	atomic_dec(&fc->num_waiting);
	return ERR_PTR(err);
118
119
}

120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
/*
 * Return request in fuse_file->reserved_req.  However that may
 * currently be in use.  If that is the case, wait for it to become
 * available.
 */
static struct fuse_req *get_reserved_req(struct fuse_conn *fc,
					 struct file *file)
{
	struct fuse_req *req = NULL;
	struct fuse_file *ff = file->private_data;

	do {
		wait_event(fc->blocked_waitq, ff->reserved_req);
		spin_lock(&fc->lock);
		if (ff->reserved_req) {
			req = ff->reserved_req;
			ff->reserved_req = NULL;
			get_file(file);
			req->stolen_file = file;
		}
		spin_unlock(&fc->lock);
	} while (!req);

	return req;
}

/*
 * Put stolen request back into fuse_file->reserved_req
 */
static void put_reserved_req(struct fuse_conn *fc, struct fuse_req *req)
{
	struct file *file = req->stolen_file;
	struct fuse_file *ff = file->private_data;

	spin_lock(&fc->lock);
	fuse_request_init(req);
	BUG_ON(ff->reserved_req);
	ff->reserved_req = req;
	wake_up(&fc->blocked_waitq);
	spin_unlock(&fc->lock);
	fput(file);
}

/*
 * Gets a requests for a file operation, always succeeds
 *
 * This is used for sending the FLUSH request, which must get to
 * userspace, due to POSIX locks which may need to be unlocked.
 *
 * If allocation fails due to OOM, use the reserved request in
 * fuse_file.
 *
 * This is very unlikely to deadlock accidentally, since the
 * filesystem should not have it's own file open.  If deadlock is
 * intentional, it can still be broken by "aborting" the filesystem.
 */
struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file)
{
	struct fuse_req *req;

	atomic_inc(&fc->num_waiting);
	wait_event(fc->blocked_waitq, !fc->blocked);
	req = fuse_request_alloc();
	if (!req)
		req = get_reserved_req(fc, file);

	fuse_req_init_context(req);
	req->waiting = 1;
	return req;
}

191
void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req)
192
193
{
	if (atomic_dec_and_test(&req->count)) {
194
195
		if (req->waiting)
			atomic_dec(&fc->num_waiting);
196
197
198
199
200

		if (req->stolen_file)
			put_reserved_req(fc, req);
		else
			fuse_request_free(req);
201
202
203
	}
}

204
205
/*
 * This function is called when a request is finished.  Either a reply
206
 * has arrived or it was aborted (and not yet sent) or some error
207
 * occurred during communication with userspace, or the device file
208
209
210
 * was closed.  The requester thread is woken up (if still waiting),
 * the 'end' callback is called if given, else the reference to the
 * request is released
211
 *
212
 * Called with fc->lock, unlocks it
213
214
 */
static void request_end(struct fuse_conn *fc, struct fuse_req *req)
215
	__releases(fc->lock)
216
{
217
218
	void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;
	req->end = NULL;
219
	list_del(&req->list);
220
	list_del(&req->intr_entry);
221
	req->state = FUSE_REQ_FINISHED;
222
223
224
225
226
227
	if (req->background) {
		if (fc->num_background == FUSE_MAX_BACKGROUND) {
			fc->blocked = 0;
			wake_up_all(&fc->blocked_waitq);
		}
		fc->num_background--;
228
	}
229
230
231
	spin_unlock(&fc->lock);
	dput(req->dentry);
	mntput(req->vfsmount);
232
	if (req->file)
233
234
235
236
237
238
		fput(req->file);
	wake_up(&req->waitq);
	if (end)
		end(fc, req);
	else
		fuse_put_request(fc, req);
239
240
}

241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
static void wait_answer_interruptible(struct fuse_conn *fc,
				      struct fuse_req *req)
{
	if (signal_pending(current))
		return;

	spin_unlock(&fc->lock);
	wait_event_interruptible(req->waitq, req->state == FUSE_REQ_FINISHED);
	spin_lock(&fc->lock);
}

static void queue_interrupt(struct fuse_conn *fc, struct fuse_req *req)
{
	list_add_tail(&req->intr_entry, &fc->interrupts);
	wake_up(&fc->waitq);
	kill_fasync(&fc->fasync, SIGIO, POLL_IN);
}

259
/* Called with fc->lock held.  Releases, and then reacquires it. */
260
static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
261
{
262
263
264
	if (!fc->no_interrupt) {
		/* Any signal may interrupt this */
		wait_answer_interruptible(fc, req);
265

266
267
268
269
270
271
272
273
274
275
276
277
		if (req->aborted)
			goto aborted;
		if (req->state == FUSE_REQ_FINISHED)
			return;

		req->interrupted = 1;
		if (req->state == FUSE_REQ_SENT)
			queue_interrupt(fc, req);
	}

	if (req->force) {
		spin_unlock(&fc->lock);
278
		wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
279
280
281
282
283
		spin_lock(&fc->lock);
	} else {
		sigset_t oldset;

		/* Only fatal signals may interrupt this */
284
		block_sigs(&oldset);
285
		wait_answer_interruptible(fc, req);
286
287
		restore_sigs(&oldset);
	}
288

289
290
291
292
293
294
295
296
297
	if (req->aborted)
		goto aborted;
	if (req->state == FUSE_REQ_FINISHED)
 		return;

	req->out.h.error = -EINTR;
	req->aborted = 1;

 aborted:
298
299
300
301
302
303
	if (req->locked) {
		/* This is uninterruptible sleep, because data is
		   being copied to/from the buffers of req.  During
		   locked state, there mustn't be any filesystem
		   operation (e.g. page fault), since that could lead
		   to deadlock */
304
		spin_unlock(&fc->lock);
305
		wait_event(req->waitq, !req->locked);
306
		spin_lock(&fc->lock);
307
	}
308
	if (req->state == FUSE_REQ_PENDING) {
309
310
		list_del(&req->list);
		__fuse_put_request(req);
311
312
313
314
315
	} else if (req->state == FUSE_REQ_SENT) {
		spin_unlock(&fc->lock);
		wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
		spin_lock(&fc->lock);
	}
316
317
318
319
320
321
322
323
324
325
326
327
328
}

static unsigned len_args(unsigned numargs, struct fuse_arg *args)
{
	unsigned nbytes = 0;
	unsigned i;

	for (i = 0; i < numargs; i++)
		nbytes += args[i].size;

	return nbytes;
}

329
330
331
332
333
334
335
336
337
338
static u64 fuse_get_unique(struct fuse_conn *fc)
 {
 	fc->reqctr++;
 	/* zero is special */
 	if (fc->reqctr == 0)
 		fc->reqctr = 1;

	return fc->reqctr;
}

339
340
static void queue_request(struct fuse_conn *fc, struct fuse_req *req)
{
341
	req->in.h.unique = fuse_get_unique(fc);
342
343
344
	req->in.h.len = sizeof(struct fuse_in_header) +
		len_args(req->in.numargs, (struct fuse_arg *) req->in.args);
	list_add_tail(&req->list, &fc->pending);
345
	req->state = FUSE_REQ_PENDING;
346
347
348
349
	if (!req->waiting) {
		req->waiting = 1;
		atomic_inc(&fc->num_waiting);
	}
350
	wake_up(&fc->waitq);
351
	kill_fasync(&fc->fasync, SIGIO, POLL_IN);
352
353
}

354
void request_send(struct fuse_conn *fc, struct fuse_req *req)
355
356
{
	req->isreply = 1;
357
	spin_lock(&fc->lock);
Miklos Szeredi's avatar
Miklos Szeredi committed
358
	if (!fc->connected)
359
360
361
362
363
364
365
366
367
		req->out.h.error = -ENOTCONN;
	else if (fc->conn_error)
		req->out.h.error = -ECONNREFUSED;
	else {
		queue_request(fc, req);
		/* acquire extra reference, since request is still needed
		   after request_end() */
		__fuse_get_request(req);

368
		request_wait_answer(fc, req);
369
	}
370
	spin_unlock(&fc->lock);
371
372
373
374
}

static void request_send_nowait(struct fuse_conn *fc, struct fuse_req *req)
{
375
	spin_lock(&fc->lock);
Miklos Szeredi's avatar
Miklos Szeredi committed
376
	if (fc->connected) {
377
378
379
380
381
		req->background = 1;
		fc->num_background++;
		if (fc->num_background == FUSE_MAX_BACKGROUND)
			fc->blocked = 1;

382
		queue_request(fc, req);
383
		spin_unlock(&fc->lock);
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
	} else {
		req->out.h.error = -ENOTCONN;
		request_end(fc, req);
	}
}

void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req)
{
	req->isreply = 0;
	request_send_nowait(fc, req);
}

void request_send_background(struct fuse_conn *fc, struct fuse_req *req)
{
	req->isreply = 1;
	request_send_nowait(fc, req);
}

/*
 * Lock the request.  Up to the next unlock_request() there mustn't be
 * anything that could cause a page-fault.  If the request was already
405
 * aborted bail out.
406
 */
407
static int lock_request(struct fuse_conn *fc, struct fuse_req *req)
408
409
410
{
	int err = 0;
	if (req) {
411
		spin_lock(&fc->lock);
412
		if (req->aborted)
413
414
415
			err = -ENOENT;
		else
			req->locked = 1;
416
		spin_unlock(&fc->lock);
417
418
419
420
421
	}
	return err;
}

/*
422
 * Unlock request.  If it was aborted during being locked, the
423
424
425
 * requester thread is currently waiting for it to be unlocked, so
 * wake it up.
 */
426
static void unlock_request(struct fuse_conn *fc, struct fuse_req *req)
427
428
{
	if (req) {
429
		spin_lock(&fc->lock);
430
		req->locked = 0;
431
		if (req->aborted)
432
			wake_up(&req->waitq);
433
		spin_unlock(&fc->lock);
434
435
436
437
	}
}

struct fuse_copy_state {
438
	struct fuse_conn *fc;
439
440
441
442
443
444
445
446
447
448
449
450
	int write;
	struct fuse_req *req;
	const struct iovec *iov;
	unsigned long nr_segs;
	unsigned long seglen;
	unsigned long addr;
	struct page *pg;
	void *mapaddr;
	void *buf;
	unsigned len;
};

451
452
453
static void fuse_copy_init(struct fuse_copy_state *cs, struct fuse_conn *fc,
			   int write, struct fuse_req *req,
			   const struct iovec *iov, unsigned long nr_segs)
454
455
{
	memset(cs, 0, sizeof(*cs));
456
	cs->fc = fc;
457
458
459
460
461
462
463
	cs->write = write;
	cs->req = req;
	cs->iov = iov;
	cs->nr_segs = nr_segs;
}

/* Unmap and put previous page of userspace buffer */
464
static void fuse_copy_finish(struct fuse_copy_state *cs)
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
{
	if (cs->mapaddr) {
		kunmap_atomic(cs->mapaddr, KM_USER0);
		if (cs->write) {
			flush_dcache_page(cs->pg);
			set_page_dirty_lock(cs->pg);
		}
		put_page(cs->pg);
		cs->mapaddr = NULL;
	}
}

/*
 * Get another pagefull of userspace buffer, and map it to kernel
 * address space, and lock request
 */
static int fuse_copy_fill(struct fuse_copy_state *cs)
{
	unsigned long offset;
	int err;

486
	unlock_request(cs->fc, cs->req);
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
	fuse_copy_finish(cs);
	if (!cs->seglen) {
		BUG_ON(!cs->nr_segs);
		cs->seglen = cs->iov[0].iov_len;
		cs->addr = (unsigned long) cs->iov[0].iov_base;
		cs->iov ++;
		cs->nr_segs --;
	}
	down_read(&current->mm->mmap_sem);
	err = get_user_pages(current, current->mm, cs->addr, 1, cs->write, 0,
			     &cs->pg, NULL);
	up_read(&current->mm->mmap_sem);
	if (err < 0)
		return err;
	BUG_ON(err != 1);
	offset = cs->addr % PAGE_SIZE;
	cs->mapaddr = kmap_atomic(cs->pg, KM_USER0);
	cs->buf = cs->mapaddr + offset;
	cs->len = min(PAGE_SIZE - offset, cs->seglen);
	cs->seglen -= cs->len;
	cs->addr += cs->len;

509
	return lock_request(cs->fc, cs->req);
510
511
512
}

/* Do as much copy to/from userspace buffer as we can */
513
static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
{
	unsigned ncpy = min(*size, cs->len);
	if (val) {
		if (cs->write)
			memcpy(cs->buf, *val, ncpy);
		else
			memcpy(*val, cs->buf, ncpy);
		*val += ncpy;
	}
	*size -= ncpy;
	cs->len -= ncpy;
	cs->buf += ncpy;
	return ncpy;
}

/*
 * Copy a page in the request to/from the userspace buffer.  Must be
 * done atomically
 */
533
534
static int fuse_copy_page(struct fuse_copy_state *cs, struct page *page,
			  unsigned offset, unsigned count, int zeroing)
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
{
	if (page && zeroing && count < PAGE_SIZE) {
		void *mapaddr = kmap_atomic(page, KM_USER1);
		memset(mapaddr, 0, PAGE_SIZE);
		kunmap_atomic(mapaddr, KM_USER1);
	}
	while (count) {
		int err;
		if (!cs->len && (err = fuse_copy_fill(cs)))
			return err;
		if (page) {
			void *mapaddr = kmap_atomic(page, KM_USER1);
			void *buf = mapaddr + offset;
			offset += fuse_copy_do(cs, &buf, &count);
			kunmap_atomic(mapaddr, KM_USER1);
		} else
			offset += fuse_copy_do(cs, NULL, &count);
	}
	if (page && !cs->write)
		flush_dcache_page(page);
	return 0;
}

/* Copy pages in the request to/from userspace buffer */
static int fuse_copy_pages(struct fuse_copy_state *cs, unsigned nbytes,
			   int zeroing)
{
	unsigned i;
	struct fuse_req *req = cs->req;
	unsigned offset = req->page_offset;
	unsigned count = min(nbytes, (unsigned) PAGE_SIZE - offset);

	for (i = 0; i < req->num_pages && (nbytes || zeroing); i++) {
		struct page *page = req->pages[i];
		int err = fuse_copy_page(cs, page, offset, count, zeroing);
		if (err)
			return err;

		nbytes -= count;
		count = min(nbytes, (unsigned) PAGE_SIZE);
		offset = 0;
	}
	return 0;
}

/* Copy a single argument in the request to/from userspace buffer */
static int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned size)
{
	while (size) {
		int err;
		if (!cs->len && (err = fuse_copy_fill(cs)))
			return err;
		fuse_copy_do(cs, &val, &size);
	}
	return 0;
}

/* Copy request arguments to/from userspace buffer */
static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs,
			  unsigned argpages, struct fuse_arg *args,
			  int zeroing)
{
	int err = 0;
	unsigned i;

	for (i = 0; !err && i < numargs; i++)  {
		struct fuse_arg *arg = &args[i];
		if (i == numargs - 1 && argpages)
			err = fuse_copy_pages(cs, arg->size, zeroing);
		else
			err = fuse_copy_one(cs, arg->value, arg->size);
	}
	return err;
}

610
611
612
613
614
static int request_pending(struct fuse_conn *fc)
{
	return !list_empty(&fc->pending) || !list_empty(&fc->interrupts);
}

615
616
617
618
619
620
/* Wait until a request is available on the pending list */
static void request_wait(struct fuse_conn *fc)
{
	DECLARE_WAITQUEUE(wait, current);

	add_wait_queue_exclusive(&fc->waitq, &wait);
621
	while (fc->connected && !request_pending(fc)) {
622
623
624
625
		set_current_state(TASK_INTERRUPTIBLE);
		if (signal_pending(current))
			break;

626
		spin_unlock(&fc->lock);
627
		schedule();
628
		spin_lock(&fc->lock);
629
630
631
632
633
	}
	set_current_state(TASK_RUNNING);
	remove_wait_queue(&fc->waitq, &wait);
}

634
635
636
637
638
639
640
641
642
643
/*
 * Transfer an interrupt request to userspace
 *
 * Unlike other requests this is assembled on demand, without a need
 * to allocate a separate fuse_req structure.
 *
 * Called with fc->lock held, releases it
 */
static int fuse_read_interrupt(struct fuse_conn *fc, struct fuse_req *req,
			       const struct iovec *iov, unsigned long nr_segs)
644
	__releases(fc->lock)
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
{
	struct fuse_copy_state cs;
	struct fuse_in_header ih;
	struct fuse_interrupt_in arg;
	unsigned reqsize = sizeof(ih) + sizeof(arg);
	int err;

	list_del_init(&req->intr_entry);
	req->intr_unique = fuse_get_unique(fc);
	memset(&ih, 0, sizeof(ih));
	memset(&arg, 0, sizeof(arg));
	ih.len = reqsize;
	ih.opcode = FUSE_INTERRUPT;
	ih.unique = req->intr_unique;
	arg.unique = req->in.h.unique;

	spin_unlock(&fc->lock);
	if (iov_length(iov, nr_segs) < reqsize)
		return -EINVAL;

	fuse_copy_init(&cs, fc, 1, NULL, iov, nr_segs);
	err = fuse_copy_one(&cs, &ih, sizeof(ih));
	if (!err)
		err = fuse_copy_one(&cs, &arg, sizeof(arg));
	fuse_copy_finish(&cs);

	return err ? err : reqsize;
}

674
675
676
677
/*
 * Read a single request into the userspace filesystem's buffer.  This
 * function waits until a request is available, then removes it from
 * the pending list and copies request data to userspace buffer.  If
678
679
 * no reply is needed (FORGET) or request has been aborted or there
 * was an error during the copying then it's finished by calling
680
681
682
 * request_end().  Otherwise add it to the processing list, and set
 * the 'sent' flag.
 */
683
684
static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
			      unsigned long nr_segs, loff_t pos)
685
686
687
688
689
690
{
	int err;
	struct fuse_req *req;
	struct fuse_in *in;
	struct fuse_copy_state cs;
	unsigned reqsize;
691
	struct file *file = iocb->ki_filp;
692
693
694
	struct fuse_conn *fc = fuse_get_conn(file);
	if (!fc)
		return -EPERM;
695

696
 restart:
697
	spin_lock(&fc->lock);
698
699
	err = -EAGAIN;
	if ((file->f_flags & O_NONBLOCK) && fc->connected &&
700
	    !request_pending(fc))
701
702
		goto err_unlock;

703
704
	request_wait(fc);
	err = -ENODEV;
705
	if (!fc->connected)
706
707
		goto err_unlock;
	err = -ERESTARTSYS;
708
	if (!request_pending(fc))
709
710
		goto err_unlock;

711
712
713
714
715
716
	if (!list_empty(&fc->interrupts)) {
		req = list_entry(fc->interrupts.next, struct fuse_req,
				 intr_entry);
		return fuse_read_interrupt(fc, req, iov, nr_segs);
	}

717
	req = list_entry(fc->pending.next, struct fuse_req, list);
718
	req->state = FUSE_REQ_READING;
719
	list_move(&req->list, &fc->io);
720
721

	in = &req->in;
722
723
724
725
726
727
728
729
730
	reqsize = in->h.len;
	/* If request is too large, reply with an error and restart the read */
	if (iov_length(iov, nr_segs) < reqsize) {
		req->out.h.error = -EIO;
		/* SETXATTR is special, since it may contain too large data */
		if (in->h.opcode == FUSE_SETXATTR)
			req->out.h.error = -E2BIG;
		request_end(fc, req);
		goto restart;
731
	}
732
733
	spin_unlock(&fc->lock);
	fuse_copy_init(&cs, fc, 1, req, iov, nr_segs);
734
735
736
737
	err = fuse_copy_one(&cs, &in->h, sizeof(in->h));
	if (!err)
		err = fuse_copy_args(&cs, in->numargs, in->argpages,
				     (struct fuse_arg *) in->args, 0);
738
	fuse_copy_finish(&cs);
739
	spin_lock(&fc->lock);
740
	req->locked = 0;
741
	if (!err && req->aborted)
742
743
		err = -ENOENT;
	if (err) {
744
		if (!req->aborted)
745
746
747
748
749
750
751
			req->out.h.error = -EIO;
		request_end(fc, req);
		return err;
	}
	if (!req->isreply)
		request_end(fc, req);
	else {
752
		req->state = FUSE_REQ_SENT;
753
		list_move_tail(&req->list, &fc->processing);
754
755
		if (req->interrupted)
			queue_interrupt(fc, req);
756
		spin_unlock(&fc->lock);
757
758
759
760
	}
	return reqsize;

 err_unlock:
761
	spin_unlock(&fc->lock);
762
763
764
765
766
767
768
769
770
771
772
	return err;
}

/* Look up request on processing list by unique ID */
static struct fuse_req *request_find(struct fuse_conn *fc, u64 unique)
{
	struct list_head *entry;

	list_for_each(entry, &fc->processing) {
		struct fuse_req *req;
		req = list_entry(entry, struct fuse_req, list);
773
		if (req->in.h.unique == unique || req->intr_unique == unique)
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
			return req;
	}
	return NULL;
}

static int copy_out_args(struct fuse_copy_state *cs, struct fuse_out *out,
			 unsigned nbytes)
{
	unsigned reqsize = sizeof(struct fuse_out_header);

	if (out->h.error)
		return nbytes != reqsize ? -EINVAL : 0;

	reqsize += len_args(out->numargs, out->args);

	if (reqsize < nbytes || (reqsize > nbytes && !out->argvar))
		return -EINVAL;
	else if (reqsize > nbytes) {
		struct fuse_arg *lastarg = &out->args[out->numargs-1];
		unsigned diffsize = reqsize - nbytes;
		if (diffsize > lastarg->size)
			return -EINVAL;
		lastarg->size -= diffsize;
	}
	return fuse_copy_args(cs, out->numargs, out->argpages, out->args,
			      out->page_zeroing);
}

/*
 * Write a single reply to a request.  First the header is copied from
 * the write buffer.  The request is then searched on the processing
 * list by the unique ID found in the header.  If found, then remove
 * it from the list and copy the rest of the buffer to the request.
 * The request is finished by calling request_end()
 */
809
810
static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov,
			       unsigned long nr_segs, loff_t pos)
811
812
813
814
815
816
{
	int err;
	unsigned nbytes = iov_length(iov, nr_segs);
	struct fuse_req *req;
	struct fuse_out_header oh;
	struct fuse_copy_state cs;
817
	struct fuse_conn *fc = fuse_get_conn(iocb->ki_filp);
818
	if (!fc)
819
		return -EPERM;
820

821
	fuse_copy_init(&cs, fc, 0, NULL, iov, nr_segs);
822
823
824
825
826
827
828
829
830
831
832
	if (nbytes < sizeof(struct fuse_out_header))
		return -EINVAL;

	err = fuse_copy_one(&cs, &oh, sizeof(oh));
	if (err)
		goto err_finish;
	err = -EINVAL;
	if (!oh.unique || oh.error <= -1000 || oh.error > 0 ||
	    oh.len != nbytes)
		goto err_finish;

833
	spin_lock(&fc->lock);
834
835
836
837
	err = -ENOENT;
	if (!fc->connected)
		goto err_unlock;

838
839
840
841
	req = request_find(fc, oh.unique);
	if (!req)
		goto err_unlock;

842
	if (req->aborted) {
843
		spin_unlock(&fc->lock);
844
		fuse_copy_finish(&cs);
845
		spin_lock(&fc->lock);
846
		request_end(fc, req);
847
848
		return -ENOENT;
	}
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
	/* Is it an interrupt reply? */
	if (req->intr_unique == oh.unique) {
		err = -EINVAL;
		if (nbytes != sizeof(struct fuse_out_header))
			goto err_unlock;

		if (oh.error == -ENOSYS)
			fc->no_interrupt = 1;
		else if (oh.error == -EAGAIN)
			queue_interrupt(fc, req);

		spin_unlock(&fc->lock);
		fuse_copy_finish(&cs);
		return nbytes;
	}

	req->state = FUSE_REQ_WRITING;
866
	list_move(&req->list, &fc->io);
867
868
869
	req->out.h = oh;
	req->locked = 1;
	cs.req = req;
870
	spin_unlock(&fc->lock);
871
872
873
874

	err = copy_out_args(&cs, &req->out, nbytes);
	fuse_copy_finish(&cs);

875
	spin_lock(&fc->lock);
876
877
	req->locked = 0;
	if (!err) {
878
		if (req->aborted)
879
			err = -ENOENT;
880
	} else if (!req->aborted)
881
882
883
884
885
886
		req->out.h.error = -EIO;
	request_end(fc, req);

	return err ? err : nbytes;

 err_unlock:
887
	spin_unlock(&fc->lock);
888
889
890
891
892
893
894
895
 err_finish:
	fuse_copy_finish(&cs);
	return err;
}

static unsigned fuse_dev_poll(struct file *file, poll_table *wait)
{
	unsigned mask = POLLOUT | POLLWRNORM;
896
	struct fuse_conn *fc = fuse_get_conn(file);
897
	if (!fc)
898
		return POLLERR;
899
900
901

	poll_wait(file, &fc->waitq, wait);

902
	spin_lock(&fc->lock);
903
904
	if (!fc->connected)
		mask = POLLERR;
905
	else if (request_pending(fc))
906
		mask |= POLLIN | POLLRDNORM;
907
	spin_unlock(&fc->lock);
908
909
910
911

	return mask;
}

912
913
914
/*
 * Abort all requests on the given list (pending or processing)
 *
915
 * This function releases and reacquires fc->lock
916
 */
917
918
919
920
921
922
923
static void end_requests(struct fuse_conn *fc, struct list_head *head)
{
	while (!list_empty(head)) {
		struct fuse_req *req;
		req = list_entry(head->next, struct fuse_req, list);
		req->out.h.error = -ECONNABORTED;
		request_end(fc, req);
924
		spin_lock(&fc->lock);
925
926
927
	}
}

928
929
930
/*
 * Abort requests under I/O
 *
931
 * The requests are set to aborted and finished, and the request
932
933
 * waiter is woken up.  This will make request_wait_answer() wait
 * until the request is unlocked and then return.
934
935
936
937
 *
 * If the request is asynchronous, then the end function needs to be
 * called after waiting for the request to be unlocked (if it was
 * locked).
938
939
940
941
 */
static void end_io_requests(struct fuse_conn *fc)
{
	while (!list_empty(&fc->io)) {
942
943
944
945
		struct fuse_req *req =
			list_entry(fc->io.next, struct fuse_req, list);
		void (*end) (struct fuse_conn *, struct fuse_req *) = req->end;

946
		req->aborted = 1;
947
948
949
950
		req->out.h.error = -ECONNABORTED;
		req->state = FUSE_REQ_FINISHED;
		list_del_init(&req->list);
		wake_up(&req->waitq);
951
952
953
954
		if (end) {
			req->end = NULL;
			/* The end function will consume this reference */
			__fuse_get_request(req);
955
			spin_unlock(&fc->lock);
956
957
			wait_event(req->waitq, !req->locked);
			end(fc, req);
958
			spin_lock(&fc->lock);
959
		}
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
	}
}

/*
 * Abort all requests.
 *
 * Emergency exit in case of a malicious or accidental deadlock, or
 * just a hung filesystem.
 *
 * The same effect is usually achievable through killing the
 * filesystem daemon and all users of the filesystem.  The exception
 * is the combination of an asynchronous request and the tricky
 * deadlock (see Documentation/filesystems/fuse.txt).
 *
 * During the aborting, progression of requests from the pending and
 * processing lists onto the io list, and progression of new requests
 * onto the pending list is prevented by req->connected being false.
 *
 * Progression of requests under I/O to the processing list is
979
980
 * prevented by the req->aborted flag being true for these requests.
 * For this reason requests on the io list must be aborted first.
981
982
983
 */
void fuse_abort_conn(struct fuse_conn *fc)
{
984
	spin_lock(&fc->lock);
985
986
	if (fc->connected) {
		fc->connected = 0;
987
		fc->blocked = 0;
988
989
990
991
		end_io_requests(fc);
		end_requests(fc, &fc->pending);
		end_requests(fc, &fc->processing);
		wake_up_all(&fc->waitq);
992
		wake_up_all(&fc->blocked_waitq);
993
		kill_fasync(&fc->fasync, SIGIO, POLL_IN);
994
	}
995
	spin_unlock(&fc->lock);
996
997
}

998
999
static int fuse_dev_release(struct inode *inode, struct file *file)
{
1000
	struct fuse_conn *fc = fuse_get_conn(file);
1001
	if (fc) {
1002
		spin_lock(&fc->lock);
Miklos Szeredi's avatar
Miklos Szeredi committed
1003
		fc->connected = 0;
1004
1005
		end_requests(fc, &fc->pending);
		end_requests(fc, &fc->processing);
1006
		spin_unlock(&fc->lock);
1007
		fasync_helper(-1, file, 0, &fc->fasync);
1008
		fuse_conn_put(fc);
1009
	}
1010

1011
1012
1013
	return 0;
}

1014
1015
1016
1017
static int fuse_dev_fasync(int fd, struct file *file, int on)
{
	struct fuse_conn *fc = fuse_get_conn(file);
	if (!fc)
1018
		return -EPERM;
1019
1020
1021
1022
1023

	/* No locking - fasync_helper does its own locking */
	return fasync_helper(fd, file, on, &fc->fasync);
}

1024
const struct file_operations fuse_dev_operations = {
1025
1026
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
1027
1028
1029
1030
	.read		= do_sync_read,
	.aio_read	= fuse_dev_read,
	.write		= do_sync_write,
	.aio_write	= fuse_dev_write,
1031
1032
	.poll		= fuse_dev_poll,
	.release	= fuse_dev_release,
1033
	.fasync		= fuse_dev_fasync,
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
};

static struct miscdevice fuse_miscdevice = {
	.minor = FUSE_MINOR,
	.name  = "fuse",
	.fops = &fuse_dev_operations,
};

int __init fuse_dev_init(void)
{
	int err = -ENOMEM;
	fuse_req_cachep = kmem_cache_create("fuse_request",
					    sizeof(struct fuse_req),
1047
					    0, 0, NULL);
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
	if (!fuse_req_cachep)
		goto out;

	err = misc_register(&fuse_miscdevice);
	if (err)
		goto out_cache_clean;

	return 0;

 out_cache_clean:
	kmem_cache_destroy(fuse_req_cachep);
 out:
	return err;
}

void fuse_dev_cleanup(void)
{
	misc_deregister(&fuse_miscdevice);
	kmem_cache_destroy(fuse_req_cachep);
}