xref: /openbmc/linux/drivers/block/loop.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  *  linux/drivers/block/loop.c
3  *
4  *  Written by Theodore Ts'o, 3/29/93
5  *
6  * Copyright 1993 by Theodore Ts'o.  Redistribution of this file is
7  * permitted under the GNU General Public License.
8  *
9  * DES encryption plus some minor changes by Werner Almesberger, 30-MAY-1993
10  * more DES encryption plus IDEA encryption by Nicholas J. Leon, June 20, 1996
11  *
12  * Modularized and updated for 1.1.16 kernel - Mitch Dsouza 28th May 1994
13  * Adapted for 1.3.59 kernel - Andries Brouwer, 1 Feb 1996
14  *
15  * Fixed do_loop_request() re-entrancy - Vincent.Renardias@waw.com Mar 20, 1997
16  *
17  * Added devfs support - Richard Gooch <rgooch@atnf.csiro.au> 16-Jan-1998
18  *
19  * Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998
20  *
21  * Loadable modules and other fixes by AK, 1998
22  *
23  * Make real block number available to downstream transfer functions, enables
24  * CBC (and relatives) mode encryption requiring unique IVs per data block.
25  * Reed H. Petty, rhp@draper.net
26  *
27  * Maximum number of loop devices now dynamic via max_loop module parameter.
28  * Russell Kroll <rkroll@exploits.org> 19990701
29  *
30  * Maximum number of loop devices when compiled-in now selectable by passing
31  * max_loop=<1-255> to the kernel on boot.
32  * Erik I. Bols�, <eriki@himolde.no>, Oct 31, 1999
33  *
34  * Completely rewrite request handling to be make_request_fn style and
35  * non blocking, pushing work to a helper thread. Lots of fixes from
36  * Al Viro too.
37  * Jens Axboe <axboe@suse.de>, Nov 2000
38  *
39  * Support up to 256 loop devices
40  * Heinz Mauelshagen <mge@sistina.com>, Feb 2002
41  *
42  * Support for falling back on the write file operation when the address space
43  * operations prepare_write and/or commit_write are not available on the
44  * backing filesystem.
45  * Anton Altaparmakov, 16 Feb 2005
46  *
47  * Still To Fix:
48  * - Advisory locking is ignored here.
49  * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
50  *
51  */
52 
53 #include <linux/module.h>
54 #include <linux/moduleparam.h>
55 #include <linux/sched.h>
56 #include <linux/fs.h>
57 #include <linux/file.h>
58 #include <linux/stat.h>
59 #include <linux/errno.h>
60 #include <linux/major.h>
61 #include <linux/wait.h>
62 #include <linux/blkdev.h>
63 #include <linux/blkpg.h>
64 #include <linux/init.h>
65 #include <linux/smp_lock.h>
66 #include <linux/swap.h>
67 #include <linux/slab.h>
68 #include <linux/loop.h>
69 #include <linux/compat.h>
70 #include <linux/suspend.h>
71 #include <linux/writeback.h>
72 #include <linux/buffer_head.h>		/* for invalidate_bdev() */
73 #include <linux/completion.h>
74 #include <linux/highmem.h>
75 #include <linux/gfp.h>
76 #include <linux/kthread.h>
77 
78 #include <asm/uaccess.h>
79 
80 static LIST_HEAD(loop_devices);
81 static DEFINE_MUTEX(loop_devices_mutex);
82 
83 /*
84  * Transfer functions
85  */
86 static int transfer_none(struct loop_device *lo, int cmd,
87 			 struct page *raw_page, unsigned raw_off,
88 			 struct page *loop_page, unsigned loop_off,
89 			 int size, sector_t real_block)
90 {
91 	char *raw_buf = kmap_atomic(raw_page, KM_USER0) + raw_off;
92 	char *loop_buf = kmap_atomic(loop_page, KM_USER1) + loop_off;
93 
94 	if (cmd == READ)
95 		memcpy(loop_buf, raw_buf, size);
96 	else
97 		memcpy(raw_buf, loop_buf, size);
98 
99 	kunmap_atomic(raw_buf, KM_USER0);
100 	kunmap_atomic(loop_buf, KM_USER1);
101 	cond_resched();
102 	return 0;
103 }
104 
105 static int transfer_xor(struct loop_device *lo, int cmd,
106 			struct page *raw_page, unsigned raw_off,
107 			struct page *loop_page, unsigned loop_off,
108 			int size, sector_t real_block)
109 {
110 	char *raw_buf = kmap_atomic(raw_page, KM_USER0) + raw_off;
111 	char *loop_buf = kmap_atomic(loop_page, KM_USER1) + loop_off;
112 	char *in, *out, *key;
113 	int i, keysize;
114 
115 	if (cmd == READ) {
116 		in = raw_buf;
117 		out = loop_buf;
118 	} else {
119 		in = loop_buf;
120 		out = raw_buf;
121 	}
122 
123 	key = lo->lo_encrypt_key;
124 	keysize = lo->lo_encrypt_key_size;
125 	for (i = 0; i < size; i++)
126 		*out++ = *in++ ^ key[(i & 511) % keysize];
127 
128 	kunmap_atomic(raw_buf, KM_USER0);
129 	kunmap_atomic(loop_buf, KM_USER1);
130 	cond_resched();
131 	return 0;
132 }
133 
134 static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
135 {
136 	if (unlikely(info->lo_encrypt_key_size <= 0))
137 		return -EINVAL;
138 	return 0;
139 }
140 
141 static struct loop_func_table none_funcs = {
142 	.number = LO_CRYPT_NONE,
143 	.transfer = transfer_none,
144 };
145 
146 static struct loop_func_table xor_funcs = {
147 	.number = LO_CRYPT_XOR,
148 	.transfer = transfer_xor,
149 	.init = xor_init
150 };
151 
152 /* xfer_funcs[0] is special - its release function is never called */
153 static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
154 	&none_funcs,
155 	&xor_funcs
156 };
157 
158 static loff_t get_loop_size(struct loop_device *lo, struct file *file)
159 {
160 	loff_t size, offset, loopsize;
161 
162 	/* Compute loopsize in bytes */
163 	size = i_size_read(file->f_mapping->host);
164 	offset = lo->lo_offset;
165 	loopsize = size - offset;
166 	if (lo->lo_sizelimit > 0 && lo->lo_sizelimit < loopsize)
167 		loopsize = lo->lo_sizelimit;
168 
169 	/*
170 	 * Unfortunately, if we want to do I/O on the device,
171 	 * the number of 512-byte sectors has to fit into a sector_t.
172 	 */
173 	return loopsize >> 9;
174 }
175 
176 static int
177 figure_loop_size(struct loop_device *lo)
178 {
179 	loff_t size = get_loop_size(lo, lo->lo_backing_file);
180 	sector_t x = (sector_t)size;
181 
182 	if (unlikely((loff_t)x != size))
183 		return -EFBIG;
184 
185 	set_capacity(lo->lo_disk, x);
186 	return 0;
187 }
188 
189 static inline int
190 lo_do_transfer(struct loop_device *lo, int cmd,
191 	       struct page *rpage, unsigned roffs,
192 	       struct page *lpage, unsigned loffs,
193 	       int size, sector_t rblock)
194 {
195 	if (unlikely(!lo->transfer))
196 		return 0;
197 
198 	return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
199 }
200 
201 /**
202  * do_lo_send_aops - helper for writing data to a loop device
203  *
204  * This is the fast version for backing filesystems which implement the address
205  * space operations prepare_write and commit_write.
206  */
207 static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
208 		int bsize, loff_t pos, struct page *page)
209 {
210 	struct file *file = lo->lo_backing_file; /* kudos to NFsckingS */
211 	struct address_space *mapping = file->f_mapping;
212 	const struct address_space_operations *aops = mapping->a_ops;
213 	pgoff_t index;
214 	unsigned offset, bv_offs;
215 	int len, ret;
216 
217 	mutex_lock(&mapping->host->i_mutex);
218 	index = pos >> PAGE_CACHE_SHIFT;
219 	offset = pos & ((pgoff_t)PAGE_CACHE_SIZE - 1);
220 	bv_offs = bvec->bv_offset;
221 	len = bvec->bv_len;
222 	while (len > 0) {
223 		sector_t IV;
224 		unsigned size;
225 		int transfer_result;
226 
227 		IV = ((sector_t)index << (PAGE_CACHE_SHIFT - 9))+(offset >> 9);
228 		size = PAGE_CACHE_SIZE - offset;
229 		if (size > len)
230 			size = len;
231 		page = grab_cache_page(mapping, index);
232 		if (unlikely(!page))
233 			goto fail;
234 		ret = aops->prepare_write(file, page, offset,
235 					  offset + size);
236 		if (unlikely(ret)) {
237 			if (ret == AOP_TRUNCATED_PAGE) {
238 				page_cache_release(page);
239 				continue;
240 			}
241 			goto unlock;
242 		}
243 		transfer_result = lo_do_transfer(lo, WRITE, page, offset,
244 				bvec->bv_page, bv_offs, size, IV);
245 		if (unlikely(transfer_result)) {
246 			/*
247 			 * The transfer failed, but we still write the data to
248 			 * keep prepare/commit calls balanced.
249 			 */
250 			printk(KERN_ERR "loop: transfer error block %llu\n",
251 			       (unsigned long long)index);
252 			zero_user_page(page, offset, size, KM_USER0);
253 		}
254 		flush_dcache_page(page);
255 		ret = aops->commit_write(file, page, offset,
256 					 offset + size);
257 		if (unlikely(ret)) {
258 			if (ret == AOP_TRUNCATED_PAGE) {
259 				page_cache_release(page);
260 				continue;
261 			}
262 			goto unlock;
263 		}
264 		if (unlikely(transfer_result))
265 			goto unlock;
266 		bv_offs += size;
267 		len -= size;
268 		offset = 0;
269 		index++;
270 		pos += size;
271 		unlock_page(page);
272 		page_cache_release(page);
273 	}
274 	ret = 0;
275 out:
276 	mutex_unlock(&mapping->host->i_mutex);
277 	return ret;
278 unlock:
279 	unlock_page(page);
280 	page_cache_release(page);
281 fail:
282 	ret = -1;
283 	goto out;
284 }
285 
286 /**
287  * __do_lo_send_write - helper for writing data to a loop device
288  *
289  * This helper just factors out common code between do_lo_send_direct_write()
290  * and do_lo_send_write().
291  */
292 static int __do_lo_send_write(struct file *file,
293 		u8 *buf, const int len, loff_t pos)
294 {
295 	ssize_t bw;
296 	mm_segment_t old_fs = get_fs();
297 
298 	set_fs(get_ds());
299 	bw = file->f_op->write(file, buf, len, &pos);
300 	set_fs(old_fs);
301 	if (likely(bw == len))
302 		return 0;
303 	printk(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
304 			(unsigned long long)pos, len);
305 	if (bw >= 0)
306 		bw = -EIO;
307 	return bw;
308 }
309 
310 /**
311  * do_lo_send_direct_write - helper for writing data to a loop device
312  *
313  * This is the fast, non-transforming version for backing filesystems which do
314  * not implement the address space operations prepare_write and commit_write.
315  * It uses the write file operation which should be present on all writeable
316  * filesystems.
317  */
318 static int do_lo_send_direct_write(struct loop_device *lo,
319 		struct bio_vec *bvec, int bsize, loff_t pos, struct page *page)
320 {
321 	ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
322 			kmap(bvec->bv_page) + bvec->bv_offset,
323 			bvec->bv_len, pos);
324 	kunmap(bvec->bv_page);
325 	cond_resched();
326 	return bw;
327 }
328 
329 /**
330  * do_lo_send_write - helper for writing data to a loop device
331  *
332  * This is the slow, transforming version for filesystems which do not
333  * implement the address space operations prepare_write and commit_write.  It
334  * uses the write file operation which should be present on all writeable
335  * filesystems.
336  *
337  * Using fops->write is slower than using aops->{prepare,commit}_write in the
338  * transforming case because we need to double buffer the data as we cannot do
339  * the transformations in place as we do not have direct access to the
340  * destination pages of the backing file.
341  */
342 static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
343 		int bsize, loff_t pos, struct page *page)
344 {
345 	int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
346 			bvec->bv_offset, bvec->bv_len, pos >> 9);
347 	if (likely(!ret))
348 		return __do_lo_send_write(lo->lo_backing_file,
349 				page_address(page), bvec->bv_len,
350 				pos);
351 	printk(KERN_ERR "loop: Transfer error at byte offset %llu, "
352 			"length %i.\n", (unsigned long long)pos, bvec->bv_len);
353 	if (ret > 0)
354 		ret = -EIO;
355 	return ret;
356 }
357 
358 static int lo_send(struct loop_device *lo, struct bio *bio, int bsize,
359 		loff_t pos)
360 {
361 	int (*do_lo_send)(struct loop_device *, struct bio_vec *, int, loff_t,
362 			struct page *page);
363 	struct bio_vec *bvec;
364 	struct page *page = NULL;
365 	int i, ret = 0;
366 
367 	do_lo_send = do_lo_send_aops;
368 	if (!(lo->lo_flags & LO_FLAGS_USE_AOPS)) {
369 		do_lo_send = do_lo_send_direct_write;
370 		if (lo->transfer != transfer_none) {
371 			page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
372 			if (unlikely(!page))
373 				goto fail;
374 			kmap(page);
375 			do_lo_send = do_lo_send_write;
376 		}
377 	}
378 	bio_for_each_segment(bvec, bio, i) {
379 		ret = do_lo_send(lo, bvec, bsize, pos, page);
380 		if (ret < 0)
381 			break;
382 		pos += bvec->bv_len;
383 	}
384 	if (page) {
385 		kunmap(page);
386 		__free_page(page);
387 	}
388 out:
389 	return ret;
390 fail:
391 	printk(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
392 	ret = -ENOMEM;
393 	goto out;
394 }
395 
396 struct lo_read_data {
397 	struct loop_device *lo;
398 	struct page *page;
399 	unsigned offset;
400 	int bsize;
401 };
402 
403 static int
404 lo_read_actor(read_descriptor_t *desc, struct page *page,
405 	      unsigned long offset, unsigned long size)
406 {
407 	unsigned long count = desc->count;
408 	struct lo_read_data *p = desc->arg.data;
409 	struct loop_device *lo = p->lo;
410 	sector_t IV;
411 
412 	IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9))+(offset >> 9);
413 
414 	if (size > count)
415 		size = count;
416 
417 	if (lo_do_transfer(lo, READ, page, offset, p->page, p->offset, size, IV)) {
418 		size = 0;
419 		printk(KERN_ERR "loop: transfer error block %ld\n",
420 		       page->index);
421 		desc->error = -EINVAL;
422 	}
423 
424 	flush_dcache_page(p->page);
425 
426 	desc->count = count - size;
427 	desc->written += size;
428 	p->offset += size;
429 	return size;
430 }
431 
432 static int
433 do_lo_receive(struct loop_device *lo,
434 	      struct bio_vec *bvec, int bsize, loff_t pos)
435 {
436 	struct lo_read_data cookie;
437 	struct file *file;
438 	int retval;
439 
440 	cookie.lo = lo;
441 	cookie.page = bvec->bv_page;
442 	cookie.offset = bvec->bv_offset;
443 	cookie.bsize = bsize;
444 	file = lo->lo_backing_file;
445 	retval = file->f_op->sendfile(file, &pos, bvec->bv_len,
446 			lo_read_actor, &cookie);
447 	return (retval < 0)? retval: 0;
448 }
449 
450 static int
451 lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos)
452 {
453 	struct bio_vec *bvec;
454 	int i, ret = 0;
455 
456 	bio_for_each_segment(bvec, bio, i) {
457 		ret = do_lo_receive(lo, bvec, bsize, pos);
458 		if (ret < 0)
459 			break;
460 		pos += bvec->bv_len;
461 	}
462 	return ret;
463 }
464 
465 static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
466 {
467 	loff_t pos;
468 	int ret;
469 
470 	pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
471 	if (bio_rw(bio) == WRITE)
472 		ret = lo_send(lo, bio, lo->lo_blocksize, pos);
473 	else
474 		ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
475 	return ret;
476 }
477 
478 /*
479  * Add bio to back of pending list
480  */
481 static void loop_add_bio(struct loop_device *lo, struct bio *bio)
482 {
483 	if (lo->lo_biotail) {
484 		lo->lo_biotail->bi_next = bio;
485 		lo->lo_biotail = bio;
486 	} else
487 		lo->lo_bio = lo->lo_biotail = bio;
488 }
489 
490 /*
491  * Grab first pending buffer
492  */
493 static struct bio *loop_get_bio(struct loop_device *lo)
494 {
495 	struct bio *bio;
496 
497 	if ((bio = lo->lo_bio)) {
498 		if (bio == lo->lo_biotail)
499 			lo->lo_biotail = NULL;
500 		lo->lo_bio = bio->bi_next;
501 		bio->bi_next = NULL;
502 	}
503 
504 	return bio;
505 }
506 
507 static int loop_make_request(request_queue_t *q, struct bio *old_bio)
508 {
509 	struct loop_device *lo = q->queuedata;
510 	int rw = bio_rw(old_bio);
511 
512 	if (rw == READA)
513 		rw = READ;
514 
515 	BUG_ON(!lo || (rw != READ && rw != WRITE));
516 
517 	spin_lock_irq(&lo->lo_lock);
518 	if (lo->lo_state != Lo_bound)
519 		goto out;
520 	if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))
521 		goto out;
522 	loop_add_bio(lo, old_bio);
523 	wake_up(&lo->lo_event);
524 	spin_unlock_irq(&lo->lo_lock);
525 	return 0;
526 
527 out:
528 	spin_unlock_irq(&lo->lo_lock);
529 	bio_io_error(old_bio, old_bio->bi_size);
530 	return 0;
531 }
532 
533 /*
534  * kick off io on the underlying address space
535  */
536 static void loop_unplug(request_queue_t *q)
537 {
538 	struct loop_device *lo = q->queuedata;
539 
540 	clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags);
541 	blk_run_address_space(lo->lo_backing_file->f_mapping);
542 }
543 
544 struct switch_request {
545 	struct file *file;
546 	struct completion wait;
547 };
548 
549 static void do_loop_switch(struct loop_device *, struct switch_request *);
550 
551 static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio)
552 {
553 	if (unlikely(!bio->bi_bdev)) {
554 		do_loop_switch(lo, bio->bi_private);
555 		bio_put(bio);
556 	} else {
557 		int ret = do_bio_filebacked(lo, bio);
558 		bio_endio(bio, bio->bi_size, ret);
559 	}
560 }
561 
562 /*
563  * worker thread that handles reads/writes to file backed loop devices,
564  * to avoid blocking in our make_request_fn. it also does loop decrypting
565  * on reads for block backed loop, as that is too heavy to do from
566  * b_end_io context where irqs may be disabled.
567  *
568  * Loop explanation:  loop_clr_fd() sets lo_state to Lo_rundown before
569  * calling kthread_stop().  Therefore once kthread_should_stop() is
570  * true, make_request will not place any more requests.  Therefore
571  * once kthread_should_stop() is true and lo_bio is NULL, we are
572  * done with the loop.
573  */
574 static int loop_thread(void *data)
575 {
576 	struct loop_device *lo = data;
577 	struct bio *bio;
578 
579 	/*
580 	 * loop can be used in an encrypted device,
581 	 * hence, it mustn't be stopped at all
582 	 * because it could be indirectly used during suspension
583 	 */
584 	current->flags |= PF_NOFREEZE;
585 
586 	set_user_nice(current, -20);
587 
588 	while (!kthread_should_stop() || lo->lo_bio) {
589 
590 		wait_event_interruptible(lo->lo_event,
591 				lo->lo_bio || kthread_should_stop());
592 
593 		if (!lo->lo_bio)
594 			continue;
595 		spin_lock_irq(&lo->lo_lock);
596 		bio = loop_get_bio(lo);
597 		spin_unlock_irq(&lo->lo_lock);
598 
599 		BUG_ON(!bio);
600 		loop_handle_bio(lo, bio);
601 	}
602 
603 	return 0;
604 }
605 
606 /*
607  * loop_switch performs the hard work of switching a backing store.
608  * First it needs to flush existing IO, it does this by sending a magic
609  * BIO down the pipe. The completion of this BIO does the actual switch.
610  */
611 static int loop_switch(struct loop_device *lo, struct file *file)
612 {
613 	struct switch_request w;
614 	struct bio *bio = bio_alloc(GFP_KERNEL, 1);
615 	if (!bio)
616 		return -ENOMEM;
617 	init_completion(&w.wait);
618 	w.file = file;
619 	bio->bi_private = &w;
620 	bio->bi_bdev = NULL;
621 	loop_make_request(lo->lo_queue, bio);
622 	wait_for_completion(&w.wait);
623 	return 0;
624 }
625 
626 /*
627  * Do the actual switch; called from the BIO completion routine
628  */
629 static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
630 {
631 	struct file *file = p->file;
632 	struct file *old_file = lo->lo_backing_file;
633 	struct address_space *mapping = file->f_mapping;
634 
635 	mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
636 	lo->lo_backing_file = file;
637 	lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
638 		mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
639 	lo->old_gfp_mask = mapping_gfp_mask(mapping);
640 	mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
641 	complete(&p->wait);
642 }
643 
644 
645 /*
646  * loop_change_fd switched the backing store of a loopback device to
647  * a new file. This is useful for operating system installers to free up
648  * the original file and in High Availability environments to switch to
649  * an alternative location for the content in case of server meltdown.
650  * This can only work if the loop device is used read-only, and if the
651  * new backing store is the same size and type as the old backing store.
652  */
653 static int loop_change_fd(struct loop_device *lo, struct file *lo_file,
654 		       struct block_device *bdev, unsigned int arg)
655 {
656 	struct file	*file, *old_file;
657 	struct inode	*inode;
658 	int		error;
659 
660 	error = -ENXIO;
661 	if (lo->lo_state != Lo_bound)
662 		goto out;
663 
664 	/* the loop device has to be read-only */
665 	error = -EINVAL;
666 	if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
667 		goto out;
668 
669 	error = -EBADF;
670 	file = fget(arg);
671 	if (!file)
672 		goto out;
673 
674 	inode = file->f_mapping->host;
675 	old_file = lo->lo_backing_file;
676 
677 	error = -EINVAL;
678 
679 	if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
680 		goto out_putf;
681 
682 	/* new backing store needs to support loop (eg sendfile) */
683 	if (!inode->i_fop->sendfile)
684 		goto out_putf;
685 
686 	/* size of the new backing store needs to be the same */
687 	if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
688 		goto out_putf;
689 
690 	/* and ... switch */
691 	error = loop_switch(lo, file);
692 	if (error)
693 		goto out_putf;
694 
695 	fput(old_file);
696 	return 0;
697 
698  out_putf:
699 	fput(file);
700  out:
701 	return error;
702 }
703 
704 static inline int is_loop_device(struct file *file)
705 {
706 	struct inode *i = file->f_mapping->host;
707 
708 	return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
709 }
710 
711 static int loop_set_fd(struct loop_device *lo, struct file *lo_file,
712 		       struct block_device *bdev, unsigned int arg)
713 {
714 	struct file	*file, *f;
715 	struct inode	*inode;
716 	struct address_space *mapping;
717 	unsigned lo_blocksize;
718 	int		lo_flags = 0;
719 	int		error;
720 	loff_t		size;
721 
722 	/* This is safe, since we have a reference from open(). */
723 	__module_get(THIS_MODULE);
724 
725 	error = -EBADF;
726 	file = fget(arg);
727 	if (!file)
728 		goto out;
729 
730 	error = -EBUSY;
731 	if (lo->lo_state != Lo_unbound)
732 		goto out_putf;
733 
734 	/* Avoid recursion */
735 	f = file;
736 	while (is_loop_device(f)) {
737 		struct loop_device *l;
738 
739 		if (f->f_mapping->host->i_rdev == lo_file->f_mapping->host->i_rdev)
740 			goto out_putf;
741 
742 		l = f->f_mapping->host->i_bdev->bd_disk->private_data;
743 		if (l->lo_state == Lo_unbound) {
744 			error = -EINVAL;
745 			goto out_putf;
746 		}
747 		f = l->lo_backing_file;
748 	}
749 
750 	mapping = file->f_mapping;
751 	inode = mapping->host;
752 
753 	if (!(file->f_mode & FMODE_WRITE))
754 		lo_flags |= LO_FLAGS_READ_ONLY;
755 
756 	error = -EINVAL;
757 	if (S_ISREG(inode->i_mode) || S_ISBLK(inode->i_mode)) {
758 		const struct address_space_operations *aops = mapping->a_ops;
759 		/*
760 		 * If we can't read - sorry. If we only can't write - well,
761 		 * it's going to be read-only.
762 		 */
763 		if (!file->f_op->sendfile)
764 			goto out_putf;
765 		if (aops->prepare_write && aops->commit_write)
766 			lo_flags |= LO_FLAGS_USE_AOPS;
767 		if (!(lo_flags & LO_FLAGS_USE_AOPS) && !file->f_op->write)
768 			lo_flags |= LO_FLAGS_READ_ONLY;
769 
770 		lo_blocksize = S_ISBLK(inode->i_mode) ?
771 			inode->i_bdev->bd_block_size : PAGE_SIZE;
772 
773 		error = 0;
774 	} else {
775 		goto out_putf;
776 	}
777 
778 	size = get_loop_size(lo, file);
779 
780 	if ((loff_t)(sector_t)size != size) {
781 		error = -EFBIG;
782 		goto out_putf;
783 	}
784 
785 	if (!(lo_file->f_mode & FMODE_WRITE))
786 		lo_flags |= LO_FLAGS_READ_ONLY;
787 
788 	set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
789 
790 	lo->lo_blocksize = lo_blocksize;
791 	lo->lo_device = bdev;
792 	lo->lo_flags = lo_flags;
793 	lo->lo_backing_file = file;
794 	lo->transfer = transfer_none;
795 	lo->ioctl = NULL;
796 	lo->lo_sizelimit = 0;
797 	lo->old_gfp_mask = mapping_gfp_mask(mapping);
798 	mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
799 
800 	lo->lo_bio = lo->lo_biotail = NULL;
801 
802 	/*
803 	 * set queue make_request_fn, and add limits based on lower level
804 	 * device
805 	 */
806 	blk_queue_make_request(lo->lo_queue, loop_make_request);
807 	lo->lo_queue->queuedata = lo;
808 	lo->lo_queue->unplug_fn = loop_unplug;
809 
810 	set_capacity(lo->lo_disk, size);
811 	bd_set_size(bdev, size << 9);
812 
813 	set_blocksize(bdev, lo_blocksize);
814 
815 	lo->lo_thread = kthread_create(loop_thread, lo, "loop%d",
816 						lo->lo_number);
817 	if (IS_ERR(lo->lo_thread)) {
818 		error = PTR_ERR(lo->lo_thread);
819 		goto out_clr;
820 	}
821 	lo->lo_state = Lo_bound;
822 	wake_up_process(lo->lo_thread);
823 	return 0;
824 
825 out_clr:
826 	lo->lo_thread = NULL;
827 	lo->lo_device = NULL;
828 	lo->lo_backing_file = NULL;
829 	lo->lo_flags = 0;
830 	set_capacity(lo->lo_disk, 0);
831 	invalidate_bdev(bdev);
832 	bd_set_size(bdev, 0);
833 	mapping_set_gfp_mask(mapping, lo->old_gfp_mask);
834 	lo->lo_state = Lo_unbound;
835  out_putf:
836 	fput(file);
837  out:
838 	/* This is safe: open() is still holding a reference. */
839 	module_put(THIS_MODULE);
840 	return error;
841 }
842 
843 static int
844 loop_release_xfer(struct loop_device *lo)
845 {
846 	int err = 0;
847 	struct loop_func_table *xfer = lo->lo_encryption;
848 
849 	if (xfer) {
850 		if (xfer->release)
851 			err = xfer->release(lo);
852 		lo->transfer = NULL;
853 		lo->lo_encryption = NULL;
854 		module_put(xfer->owner);
855 	}
856 	return err;
857 }
858 
859 static int
860 loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
861 	       const struct loop_info64 *i)
862 {
863 	int err = 0;
864 
865 	if (xfer) {
866 		struct module *owner = xfer->owner;
867 
868 		if (!try_module_get(owner))
869 			return -EINVAL;
870 		if (xfer->init)
871 			err = xfer->init(lo, i);
872 		if (err)
873 			module_put(owner);
874 		else
875 			lo->lo_encryption = xfer;
876 	}
877 	return err;
878 }
879 
880 static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)
881 {
882 	struct file *filp = lo->lo_backing_file;
883 	gfp_t gfp = lo->old_gfp_mask;
884 
885 	if (lo->lo_state != Lo_bound)
886 		return -ENXIO;
887 
888 	if (lo->lo_refcnt > 1)	/* we needed one fd for the ioctl */
889 		return -EBUSY;
890 
891 	if (filp == NULL)
892 		return -EINVAL;
893 
894 	spin_lock_irq(&lo->lo_lock);
895 	lo->lo_state = Lo_rundown;
896 	spin_unlock_irq(&lo->lo_lock);
897 
898 	kthread_stop(lo->lo_thread);
899 
900 	lo->lo_backing_file = NULL;
901 
902 	loop_release_xfer(lo);
903 	lo->transfer = NULL;
904 	lo->ioctl = NULL;
905 	lo->lo_device = NULL;
906 	lo->lo_encryption = NULL;
907 	lo->lo_offset = 0;
908 	lo->lo_sizelimit = 0;
909 	lo->lo_encrypt_key_size = 0;
910 	lo->lo_flags = 0;
911 	lo->lo_thread = NULL;
912 	memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
913 	memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
914 	memset(lo->lo_file_name, 0, LO_NAME_SIZE);
915 	invalidate_bdev(bdev);
916 	set_capacity(lo->lo_disk, 0);
917 	bd_set_size(bdev, 0);
918 	mapping_set_gfp_mask(filp->f_mapping, gfp);
919 	lo->lo_state = Lo_unbound;
920 	fput(filp);
921 	/* This is safe: open() is still holding a reference. */
922 	module_put(THIS_MODULE);
923 	return 0;
924 }
925 
926 static int
927 loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
928 {
929 	int err;
930 	struct loop_func_table *xfer;
931 
932 	if (lo->lo_encrypt_key_size && lo->lo_key_owner != current->uid &&
933 	    !capable(CAP_SYS_ADMIN))
934 		return -EPERM;
935 	if (lo->lo_state != Lo_bound)
936 		return -ENXIO;
937 	if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
938 		return -EINVAL;
939 
940 	err = loop_release_xfer(lo);
941 	if (err)
942 		return err;
943 
944 	if (info->lo_encrypt_type) {
945 		unsigned int type = info->lo_encrypt_type;
946 
947 		if (type >= MAX_LO_CRYPT)
948 			return -EINVAL;
949 		xfer = xfer_funcs[type];
950 		if (xfer == NULL)
951 			return -EINVAL;
952 	} else
953 		xfer = NULL;
954 
955 	err = loop_init_xfer(lo, xfer, info);
956 	if (err)
957 		return err;
958 
959 	if (lo->lo_offset != info->lo_offset ||
960 	    lo->lo_sizelimit != info->lo_sizelimit) {
961 		lo->lo_offset = info->lo_offset;
962 		lo->lo_sizelimit = info->lo_sizelimit;
963 		if (figure_loop_size(lo))
964 			return -EFBIG;
965 	}
966 
967 	memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
968 	memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
969 	lo->lo_file_name[LO_NAME_SIZE-1] = 0;
970 	lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
971 
972 	if (!xfer)
973 		xfer = &none_funcs;
974 	lo->transfer = xfer->transfer;
975 	lo->ioctl = xfer->ioctl;
976 
977 	lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
978 	lo->lo_init[0] = info->lo_init[0];
979 	lo->lo_init[1] = info->lo_init[1];
980 	if (info->lo_encrypt_key_size) {
981 		memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
982 		       info->lo_encrypt_key_size);
983 		lo->lo_key_owner = current->uid;
984 	}
985 
986 	return 0;
987 }
988 
989 static int
990 loop_get_status(struct loop_device *lo, struct loop_info64 *info)
991 {
992 	struct file *file = lo->lo_backing_file;
993 	struct kstat stat;
994 	int error;
995 
996 	if (lo->lo_state != Lo_bound)
997 		return -ENXIO;
998 	error = vfs_getattr(file->f_path.mnt, file->f_path.dentry, &stat);
999 	if (error)
1000 		return error;
1001 	memset(info, 0, sizeof(*info));
1002 	info->lo_number = lo->lo_number;
1003 	info->lo_device = huge_encode_dev(stat.dev);
1004 	info->lo_inode = stat.ino;
1005 	info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
1006 	info->lo_offset = lo->lo_offset;
1007 	info->lo_sizelimit = lo->lo_sizelimit;
1008 	info->lo_flags = lo->lo_flags;
1009 	memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1010 	memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1011 	info->lo_encrypt_type =
1012 		lo->lo_encryption ? lo->lo_encryption->number : 0;
1013 	if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1014 		info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1015 		memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1016 		       lo->lo_encrypt_key_size);
1017 	}
1018 	return 0;
1019 }
1020 
1021 static void
1022 loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1023 {
1024 	memset(info64, 0, sizeof(*info64));
1025 	info64->lo_number = info->lo_number;
1026 	info64->lo_device = info->lo_device;
1027 	info64->lo_inode = info->lo_inode;
1028 	info64->lo_rdevice = info->lo_rdevice;
1029 	info64->lo_offset = info->lo_offset;
1030 	info64->lo_sizelimit = 0;
1031 	info64->lo_encrypt_type = info->lo_encrypt_type;
1032 	info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1033 	info64->lo_flags = info->lo_flags;
1034 	info64->lo_init[0] = info->lo_init[0];
1035 	info64->lo_init[1] = info->lo_init[1];
1036 	if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1037 		memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1038 	else
1039 		memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1040 	memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1041 }
1042 
1043 static int
1044 loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1045 {
1046 	memset(info, 0, sizeof(*info));
1047 	info->lo_number = info64->lo_number;
1048 	info->lo_device = info64->lo_device;
1049 	info->lo_inode = info64->lo_inode;
1050 	info->lo_rdevice = info64->lo_rdevice;
1051 	info->lo_offset = info64->lo_offset;
1052 	info->lo_encrypt_type = info64->lo_encrypt_type;
1053 	info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1054 	info->lo_flags = info64->lo_flags;
1055 	info->lo_init[0] = info64->lo_init[0];
1056 	info->lo_init[1] = info64->lo_init[1];
1057 	if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1058 		memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1059 	else
1060 		memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1061 	memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1062 
1063 	/* error in case values were truncated */
1064 	if (info->lo_device != info64->lo_device ||
1065 	    info->lo_rdevice != info64->lo_rdevice ||
1066 	    info->lo_inode != info64->lo_inode ||
1067 	    info->lo_offset != info64->lo_offset)
1068 		return -EOVERFLOW;
1069 
1070 	return 0;
1071 }
1072 
1073 static int
1074 loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1075 {
1076 	struct loop_info info;
1077 	struct loop_info64 info64;
1078 
1079 	if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1080 		return -EFAULT;
1081 	loop_info64_from_old(&info, &info64);
1082 	return loop_set_status(lo, &info64);
1083 }
1084 
1085 static int
1086 loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1087 {
1088 	struct loop_info64 info64;
1089 
1090 	if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1091 		return -EFAULT;
1092 	return loop_set_status(lo, &info64);
1093 }
1094 
1095 static int
1096 loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1097 	struct loop_info info;
1098 	struct loop_info64 info64;
1099 	int err = 0;
1100 
1101 	if (!arg)
1102 		err = -EINVAL;
1103 	if (!err)
1104 		err = loop_get_status(lo, &info64);
1105 	if (!err)
1106 		err = loop_info64_to_old(&info64, &info);
1107 	if (!err && copy_to_user(arg, &info, sizeof(info)))
1108 		err = -EFAULT;
1109 
1110 	return err;
1111 }
1112 
1113 static int
1114 loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1115 	struct loop_info64 info64;
1116 	int err = 0;
1117 
1118 	if (!arg)
1119 		err = -EINVAL;
1120 	if (!err)
1121 		err = loop_get_status(lo, &info64);
1122 	if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1123 		err = -EFAULT;
1124 
1125 	return err;
1126 }
1127 
1128 static int lo_ioctl(struct inode * inode, struct file * file,
1129 	unsigned int cmd, unsigned long arg)
1130 {
1131 	struct loop_device *lo = inode->i_bdev->bd_disk->private_data;
1132 	int err;
1133 
1134 	mutex_lock(&lo->lo_ctl_mutex);
1135 	switch (cmd) {
1136 	case LOOP_SET_FD:
1137 		err = loop_set_fd(lo, file, inode->i_bdev, arg);
1138 		break;
1139 	case LOOP_CHANGE_FD:
1140 		err = loop_change_fd(lo, file, inode->i_bdev, arg);
1141 		break;
1142 	case LOOP_CLR_FD:
1143 		err = loop_clr_fd(lo, inode->i_bdev);
1144 		break;
1145 	case LOOP_SET_STATUS:
1146 		err = loop_set_status_old(lo, (struct loop_info __user *) arg);
1147 		break;
1148 	case LOOP_GET_STATUS:
1149 		err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1150 		break;
1151 	case LOOP_SET_STATUS64:
1152 		err = loop_set_status64(lo, (struct loop_info64 __user *) arg);
1153 		break;
1154 	case LOOP_GET_STATUS64:
1155 		err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1156 		break;
1157 	default:
1158 		err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1159 	}
1160 	mutex_unlock(&lo->lo_ctl_mutex);
1161 	return err;
1162 }
1163 
1164 #ifdef CONFIG_COMPAT
1165 struct compat_loop_info {
1166 	compat_int_t	lo_number;      /* ioctl r/o */
1167 	compat_dev_t	lo_device;      /* ioctl r/o */
1168 	compat_ulong_t	lo_inode;       /* ioctl r/o */
1169 	compat_dev_t	lo_rdevice;     /* ioctl r/o */
1170 	compat_int_t	lo_offset;
1171 	compat_int_t	lo_encrypt_type;
1172 	compat_int_t	lo_encrypt_key_size;    /* ioctl w/o */
1173 	compat_int_t	lo_flags;       /* ioctl r/o */
1174 	char		lo_name[LO_NAME_SIZE];
1175 	unsigned char	lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1176 	compat_ulong_t	lo_init[2];
1177 	char		reserved[4];
1178 };
1179 
1180 /*
1181  * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1182  * - noinlined to reduce stack space usage in main part of driver
1183  */
1184 static noinline int
1185 loop_info64_from_compat(const struct compat_loop_info __user *arg,
1186 			struct loop_info64 *info64)
1187 {
1188 	struct compat_loop_info info;
1189 
1190 	if (copy_from_user(&info, arg, sizeof(info)))
1191 		return -EFAULT;
1192 
1193 	memset(info64, 0, sizeof(*info64));
1194 	info64->lo_number = info.lo_number;
1195 	info64->lo_device = info.lo_device;
1196 	info64->lo_inode = info.lo_inode;
1197 	info64->lo_rdevice = info.lo_rdevice;
1198 	info64->lo_offset = info.lo_offset;
1199 	info64->lo_sizelimit = 0;
1200 	info64->lo_encrypt_type = info.lo_encrypt_type;
1201 	info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1202 	info64->lo_flags = info.lo_flags;
1203 	info64->lo_init[0] = info.lo_init[0];
1204 	info64->lo_init[1] = info.lo_init[1];
1205 	if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1206 		memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1207 	else
1208 		memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1209 	memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1210 	return 0;
1211 }
1212 
1213 /*
1214  * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1215  * - noinlined to reduce stack space usage in main part of driver
1216  */
1217 static noinline int
1218 loop_info64_to_compat(const struct loop_info64 *info64,
1219 		      struct compat_loop_info __user *arg)
1220 {
1221 	struct compat_loop_info info;
1222 
1223 	memset(&info, 0, sizeof(info));
1224 	info.lo_number = info64->lo_number;
1225 	info.lo_device = info64->lo_device;
1226 	info.lo_inode = info64->lo_inode;
1227 	info.lo_rdevice = info64->lo_rdevice;
1228 	info.lo_offset = info64->lo_offset;
1229 	info.lo_encrypt_type = info64->lo_encrypt_type;
1230 	info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
1231 	info.lo_flags = info64->lo_flags;
1232 	info.lo_init[0] = info64->lo_init[0];
1233 	info.lo_init[1] = info64->lo_init[1];
1234 	if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1235 		memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1236 	else
1237 		memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1238 	memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1239 
1240 	/* error in case values were truncated */
1241 	if (info.lo_device != info64->lo_device ||
1242 	    info.lo_rdevice != info64->lo_rdevice ||
1243 	    info.lo_inode != info64->lo_inode ||
1244 	    info.lo_offset != info64->lo_offset ||
1245 	    info.lo_init[0] != info64->lo_init[0] ||
1246 	    info.lo_init[1] != info64->lo_init[1])
1247 		return -EOVERFLOW;
1248 
1249 	if (copy_to_user(arg, &info, sizeof(info)))
1250 		return -EFAULT;
1251 	return 0;
1252 }
1253 
1254 static int
1255 loop_set_status_compat(struct loop_device *lo,
1256 		       const struct compat_loop_info __user *arg)
1257 {
1258 	struct loop_info64 info64;
1259 	int ret;
1260 
1261 	ret = loop_info64_from_compat(arg, &info64);
1262 	if (ret < 0)
1263 		return ret;
1264 	return loop_set_status(lo, &info64);
1265 }
1266 
1267 static int
1268 loop_get_status_compat(struct loop_device *lo,
1269 		       struct compat_loop_info __user *arg)
1270 {
1271 	struct loop_info64 info64;
1272 	int err = 0;
1273 
1274 	if (!arg)
1275 		err = -EINVAL;
1276 	if (!err)
1277 		err = loop_get_status(lo, &info64);
1278 	if (!err)
1279 		err = loop_info64_to_compat(&info64, arg);
1280 	return err;
1281 }
1282 
1283 static long lo_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1284 {
1285 	struct inode *inode = file->f_path.dentry->d_inode;
1286 	struct loop_device *lo = inode->i_bdev->bd_disk->private_data;
1287 	int err;
1288 
1289 	lock_kernel();
1290 	switch(cmd) {
1291 	case LOOP_SET_STATUS:
1292 		mutex_lock(&lo->lo_ctl_mutex);
1293 		err = loop_set_status_compat(
1294 			lo, (const struct compat_loop_info __user *) arg);
1295 		mutex_unlock(&lo->lo_ctl_mutex);
1296 		break;
1297 	case LOOP_GET_STATUS:
1298 		mutex_lock(&lo->lo_ctl_mutex);
1299 		err = loop_get_status_compat(
1300 			lo, (struct compat_loop_info __user *) arg);
1301 		mutex_unlock(&lo->lo_ctl_mutex);
1302 		break;
1303 	case LOOP_CLR_FD:
1304 	case LOOP_GET_STATUS64:
1305 	case LOOP_SET_STATUS64:
1306 		arg = (unsigned long) compat_ptr(arg);
1307 	case LOOP_SET_FD:
1308 	case LOOP_CHANGE_FD:
1309 		err = lo_ioctl(inode, file, cmd, arg);
1310 		break;
1311 	default:
1312 		err = -ENOIOCTLCMD;
1313 		break;
1314 	}
1315 	unlock_kernel();
1316 	return err;
1317 }
1318 #endif
1319 
1320 static int lo_open(struct inode *inode, struct file *file)
1321 {
1322 	struct loop_device *lo = inode->i_bdev->bd_disk->private_data;
1323 
1324 	mutex_lock(&lo->lo_ctl_mutex);
1325 	lo->lo_refcnt++;
1326 	mutex_unlock(&lo->lo_ctl_mutex);
1327 
1328 	return 0;
1329 }
1330 
1331 static int lo_release(struct inode *inode, struct file *file)
1332 {
1333 	struct loop_device *lo = inode->i_bdev->bd_disk->private_data;
1334 
1335 	mutex_lock(&lo->lo_ctl_mutex);
1336 	--lo->lo_refcnt;
1337 	mutex_unlock(&lo->lo_ctl_mutex);
1338 
1339 	return 0;
1340 }
1341 
1342 static struct block_device_operations lo_fops = {
1343 	.owner =	THIS_MODULE,
1344 	.open =		lo_open,
1345 	.release =	lo_release,
1346 	.ioctl =	lo_ioctl,
1347 #ifdef CONFIG_COMPAT
1348 	.compat_ioctl =	lo_compat_ioctl,
1349 #endif
1350 };
1351 
1352 /*
1353  * And now the modules code and kernel interface.
1354  */
1355 static int max_loop;
1356 module_param(max_loop, int, 0);
1357 MODULE_PARM_DESC(max_loop, "obsolete, loop device is created on-demand");
1358 MODULE_LICENSE("GPL");
1359 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1360 
1361 int loop_register_transfer(struct loop_func_table *funcs)
1362 {
1363 	unsigned int n = funcs->number;
1364 
1365 	if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1366 		return -EINVAL;
1367 	xfer_funcs[n] = funcs;
1368 	return 0;
1369 }
1370 
1371 int loop_unregister_transfer(int number)
1372 {
1373 	unsigned int n = number;
1374 	struct loop_device *lo;
1375 	struct loop_func_table *xfer;
1376 
1377 	if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1378 		return -EINVAL;
1379 
1380 	xfer_funcs[n] = NULL;
1381 
1382 	list_for_each_entry(lo, &loop_devices, lo_list) {
1383 		mutex_lock(&lo->lo_ctl_mutex);
1384 
1385 		if (lo->lo_encryption == xfer)
1386 			loop_release_xfer(lo);
1387 
1388 		mutex_unlock(&lo->lo_ctl_mutex);
1389 	}
1390 
1391 	return 0;
1392 }
1393 
1394 EXPORT_SYMBOL(loop_register_transfer);
1395 EXPORT_SYMBOL(loop_unregister_transfer);
1396 
1397 static struct loop_device *loop_init_one(int i)
1398 {
1399 	struct loop_device *lo;
1400 	struct gendisk *disk;
1401 
1402 	list_for_each_entry(lo, &loop_devices, lo_list) {
1403 		if (lo->lo_number == i)
1404 			return lo;
1405 	}
1406 
1407 	lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1408 	if (!lo)
1409 		goto out;
1410 
1411 	lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
1412 	if (!lo->lo_queue)
1413 		goto out_free_dev;
1414 
1415 	disk = lo->lo_disk = alloc_disk(1);
1416 	if (!disk)
1417 		goto out_free_queue;
1418 
1419 	mutex_init(&lo->lo_ctl_mutex);
1420 	lo->lo_number		= i;
1421 	lo->lo_thread		= NULL;
1422 	init_waitqueue_head(&lo->lo_event);
1423 	spin_lock_init(&lo->lo_lock);
1424 	disk->major		= LOOP_MAJOR;
1425 	disk->first_minor	= i;
1426 	disk->fops		= &lo_fops;
1427 	disk->private_data	= lo;
1428 	disk->queue		= lo->lo_queue;
1429 	sprintf(disk->disk_name, "loop%d", i);
1430 	add_disk(disk);
1431 	list_add_tail(&lo->lo_list, &loop_devices);
1432 	return lo;
1433 
1434 out_free_queue:
1435 	blk_cleanup_queue(lo->lo_queue);
1436 out_free_dev:
1437 	kfree(lo);
1438 out:
1439 	return NULL;
1440 }
1441 
1442 static void loop_del_one(struct loop_device *lo)
1443 {
1444 	del_gendisk(lo->lo_disk);
1445 	blk_cleanup_queue(lo->lo_queue);
1446 	put_disk(lo->lo_disk);
1447 	list_del(&lo->lo_list);
1448 	kfree(lo);
1449 }
1450 
1451 static struct kobject *loop_probe(dev_t dev, int *part, void *data)
1452 {
1453 	struct loop_device *lo;
1454 	struct kobject *kobj;
1455 
1456 	mutex_lock(&loop_devices_mutex);
1457 	lo = loop_init_one(dev & MINORMASK);
1458 	kobj = lo ? get_disk(lo->lo_disk) : ERR_PTR(-ENOMEM);
1459 	mutex_unlock(&loop_devices_mutex);
1460 
1461 	*part = 0;
1462 	return kobj;
1463 }
1464 
1465 static int __init loop_init(void)
1466 {
1467 	if (register_blkdev(LOOP_MAJOR, "loop"))
1468 		return -EIO;
1469 	blk_register_region(MKDEV(LOOP_MAJOR, 0), 1UL << MINORBITS,
1470 				  THIS_MODULE, loop_probe, NULL, NULL);
1471 
1472 	if (max_loop) {
1473 		printk(KERN_INFO "loop: the max_loop option is obsolete "
1474 				 "and will be removed in March 2008\n");
1475 
1476 	}
1477 	printk(KERN_INFO "loop: module loaded\n");
1478 	return 0;
1479 }
1480 
1481 static void __exit loop_exit(void)
1482 {
1483 	struct loop_device *lo, *next;
1484 
1485 	list_for_each_entry_safe(lo, next, &loop_devices, lo_list)
1486 		loop_del_one(lo);
1487 
1488 	blk_unregister_region(MKDEV(LOOP_MAJOR, 0), 1UL << MINORBITS);
1489 	if (unregister_blkdev(LOOP_MAJOR, "loop"))
1490 		printk(KERN_WARNING "loop: cannot unregister blkdev\n");
1491 }
1492 
1493 module_init(loop_init);
1494 module_exit(loop_exit);
1495 
1496 #ifndef MODULE
1497 static int __init max_loop_setup(char *str)
1498 {
1499 	max_loop = simple_strtol(str, NULL, 0);
1500 	return 1;
1501 }
1502 
1503 __setup("max_loop=", max_loop_setup);
1504 #endif
1505