projects/linux·blob v2.6.32 · refs

1673 lines · 40.3 KiB

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 - [email protected] Mar 20, 1997
16 *
17 * Added devfs support - Richard Gooch <[email protected]> 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, [email protected]
26 *
27 * Maximum number of loop devices now dynamic via max_loop module parameter.
28 * Russell Kroll <[email protected]> 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. Bolsø, <[email protected]>, 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 <[email protected]>, Nov 2000
38 *
39 * Support up to 256 loop devices
40 * Heinz Mauelshagen <[email protected]>, Feb 2002
41 *
42 * Support for falling back on the write file operation when the address space
43 * operations write_begin is not available on the backing filesystem.
44 * Anton Altaparmakov, 16 Feb 2005
45 *
46 * Still To Fix:
47 * - Advisory locking is ignored here.
48 * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
49 *
50 */
51
52#include <linux/module.h>
53#include <linux/moduleparam.h>
54#include <linux/sched.h>
55#include <linux/fs.h>
56#include <linux/file.h>
57#include <linux/stat.h>
58#include <linux/errno.h>
59#include <linux/major.h>
60#include <linux/wait.h>
61#include <linux/blkdev.h>
62#include <linux/blkpg.h>
63#include <linux/init.h>
64#include <linux/swap.h>
65#include <linux/slab.h>
66#include <linux/loop.h>
67#include <linux/compat.h>
68#include <linux/suspend.h>
69#include <linux/freezer.h>
70#include <linux/writeback.h>
71#include <linux/buffer_head.h> /* for invalidate_bdev() */
72#include <linux/completion.h>
73#include <linux/highmem.h>
74#include <linux/gfp.h>
75#include <linux/kthread.h>
76#include <linux/splice.h>
77
78#include <asm/uaccess.h>
79
80static LIST_HEAD(loop_devices);
81static DEFINE_MUTEX(loop_devices_mutex);
82
83static int max_part;
84static int part_shift;
85
86/*
87 * Transfer functions
88 */
89static int transfer_none(struct loop_device *lo, int cmd,
90 struct page *raw_page, unsigned raw_off,
91 struct page *loop_page, unsigned loop_off,
92 int size, sector_t real_block)
93{
94 char *raw_buf = kmap_atomic(raw_page, KM_USER0) + raw_off;
95 char *loop_buf = kmap_atomic(loop_page, KM_USER1) + loop_off;
96
97 if (cmd == READ)
98 memcpy(loop_buf, raw_buf, size);
99 else
100 memcpy(raw_buf, loop_buf, size);
101
102 kunmap_atomic(raw_buf, KM_USER0);
103 kunmap_atomic(loop_buf, KM_USER1);
104 cond_resched();
105 return 0;
106}
107
108static int transfer_xor(struct loop_device *lo, int cmd,
109 struct page *raw_page, unsigned raw_off,
110 struct page *loop_page, unsigned loop_off,
111 int size, sector_t real_block)
112{
113 char *raw_buf = kmap_atomic(raw_page, KM_USER0) + raw_off;
114 char *loop_buf = kmap_atomic(loop_page, KM_USER1) + loop_off;
115 char *in, *out, *key;
116 int i, keysize;
117
118 if (cmd == READ) {
119 in = raw_buf;
120 out = loop_buf;
121 } else {
122 in = loop_buf;
123 out = raw_buf;
124 }
125
126 key = lo->lo_encrypt_key;
127 keysize = lo->lo_encrypt_key_size;
128 for (i = 0; i < size; i++)
129 *out++ = *in++ ^ key[(i & 511) % keysize];
130
131 kunmap_atomic(raw_buf, KM_USER0);
132 kunmap_atomic(loop_buf, KM_USER1);
133 cond_resched();
134 return 0;
135}
136
137static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
138{
139 if (unlikely(info->lo_encrypt_key_size <= 0))
140 return -EINVAL;
141 return 0;
142}
143
144static struct loop_func_table none_funcs = {
145 .number = LO_CRYPT_NONE,
146 .transfer = transfer_none,
147};
148
149static struct loop_func_table xor_funcs = {
150 .number = LO_CRYPT_XOR,
151 .transfer = transfer_xor,
152 .init = xor_init
153};
154
155/* xfer_funcs[0] is special - its release function is never called */
156static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
157 &none_funcs,
158 &xor_funcs
159};
160
161static loff_t get_loop_size(struct loop_device *lo, struct file *file)
162{
163 loff_t size, offset, loopsize;
164
165 /* Compute loopsize in bytes */
166 size = i_size_read(file->f_mapping->host);
167 offset = lo->lo_offset;
168 loopsize = size - offset;
169 if (lo->lo_sizelimit > 0 && lo->lo_sizelimit < loopsize)
170 loopsize = lo->lo_sizelimit;
171
172 /*
173 * Unfortunately, if we want to do I/O on the device,
174 * the number of 512-byte sectors has to fit into a sector_t.
175 */
176 return loopsize >> 9;
177}
178
179static int
180figure_loop_size(struct loop_device *lo)
181{
182 loff_t size = get_loop_size(lo, lo->lo_backing_file);
183 sector_t x = (sector_t)size;
184
185 if (unlikely((loff_t)x != size))
186 return -EFBIG;
187
188 set_capacity(lo->lo_disk, x);
189 return 0;
190}
191
192static inline int
193lo_do_transfer(struct loop_device *lo, int cmd,
194 struct page *rpage, unsigned roffs,
195 struct page *lpage, unsigned loffs,
196 int size, sector_t rblock)
197{
198 if (unlikely(!lo->transfer))
199 return 0;
200
201 return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
202}
203
204/**
205 * do_lo_send_aops - helper for writing data to a loop device
206 *
207 * This is the fast version for backing filesystems which implement the address
208 * space operations write_begin and write_end.
209 */
210static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
211 loff_t pos, struct page *unused)
212{
213 struct file *file = lo->lo_backing_file; /* kudos to NFsckingS */
214 struct address_space *mapping = file->f_mapping;
215 pgoff_t index;
216 unsigned offset, bv_offs;
217 int len, ret;
218
219 mutex_lock(&mapping->host->i_mutex);
220 index = pos >> PAGE_CACHE_SHIFT;
221 offset = pos & ((pgoff_t)PAGE_CACHE_SIZE - 1);
222 bv_offs = bvec->bv_offset;
223 len = bvec->bv_len;
224 while (len > 0) {
225 sector_t IV;
226 unsigned size, copied;
227 int transfer_result;
228 struct page *page;
229 void *fsdata;
230
231 IV = ((sector_t)index << (PAGE_CACHE_SHIFT - 9))+(offset >> 9);
232 size = PAGE_CACHE_SIZE - offset;
233 if (size > len)
234 size = len;
235
236 ret = pagecache_write_begin(file, mapping, pos, size, 0,
237 &page, &fsdata);
238 if (ret)
239 goto fail;
240
241 transfer_result = lo_do_transfer(lo, WRITE, page, offset,
242 bvec->bv_page, bv_offs, size, IV);
243 copied = size;
244 if (unlikely(transfer_result))
245 copied = 0;
246
247 ret = pagecache_write_end(file, mapping, pos, size, copied,
248 page, fsdata);
249 if (ret < 0 || ret != copied)
250 goto fail;
251
252 if (unlikely(transfer_result))
253 goto fail;
254
255 bv_offs += copied;
256 len -= copied;
257 offset = 0;
258 index++;
259 pos += copied;
260 }
261 ret = 0;
262out:
263 mutex_unlock(&mapping->host->i_mutex);
264 return ret;
265fail:
266 ret = -1;
267 goto out;
268}
269
270/**
271 * __do_lo_send_write - helper for writing data to a loop device
272 *
273 * This helper just factors out common code between do_lo_send_direct_write()
274 * and do_lo_send_write().
275 */
276static int __do_lo_send_write(struct file *file,
277 u8 *buf, const int len, loff_t pos)
278{
279 ssize_t bw;
280 mm_segment_t old_fs = get_fs();
281
282 set_fs(get_ds());
283 bw = file->f_op->write(file, buf, len, &pos);
284 set_fs(old_fs);
285 if (likely(bw == len))
286 return 0;
287 printk(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
288 (unsigned long long)pos, len);
289 if (bw >= 0)
290 bw = -EIO;
291 return bw;
292}
293
294/**
295 * do_lo_send_direct_write - helper for writing data to a loop device
296 *
297 * This is the fast, non-transforming version for backing filesystems which do
298 * not implement the address space operations write_begin and write_end.
299 * It uses the write file operation which should be present on all writeable
300 * filesystems.
301 */
302static int do_lo_send_direct_write(struct loop_device *lo,
303 struct bio_vec *bvec, loff_t pos, struct page *page)
304{
305 ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
306 kmap(bvec->bv_page) + bvec->bv_offset,
307 bvec->bv_len, pos);
308 kunmap(bvec->bv_page);
309 cond_resched();
310 return bw;
311}
312
313/**
314 * do_lo_send_write - helper for writing data to a loop device
315 *
316 * This is the slow, transforming version for filesystems which do not
317 * implement the address space operations write_begin and write_end. It
318 * uses the write file operation which should be present on all writeable
319 * filesystems.
320 *
321 * Using fops->write is slower than using aops->{prepare,commit}_write in the
322 * transforming case because we need to double buffer the data as we cannot do
323 * the transformations in place as we do not have direct access to the
324 * destination pages of the backing file.
325 */
326static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
327 loff_t pos, struct page *page)
328{
329 int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
330 bvec->bv_offset, bvec->bv_len, pos >> 9);
331 if (likely(!ret))
332 return __do_lo_send_write(lo->lo_backing_file,
333 page_address(page), bvec->bv_len,
334 pos);
335 printk(KERN_ERR "loop: Transfer error at byte offset %llu, "
336 "length %i.\n", (unsigned long long)pos, bvec->bv_len);
337 if (ret > 0)
338 ret = -EIO;
339 return ret;
340}
341
342static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos)
343{
344 int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t,
345 struct page *page);
346 struct bio_vec *bvec;
347 struct page *page = NULL;
348 int i, ret = 0;
349
350 do_lo_send = do_lo_send_aops;
351 if (!(lo->lo_flags & LO_FLAGS_USE_AOPS)) {
352 do_lo_send = do_lo_send_direct_write;
353 if (lo->transfer != transfer_none) {
354 page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
355 if (unlikely(!page))
356 goto fail;
357 kmap(page);
358 do_lo_send = do_lo_send_write;
359 }
360 }
361 bio_for_each_segment(bvec, bio, i) {
362 ret = do_lo_send(lo, bvec, pos, page);
363 if (ret < 0)
364 break;
365 pos += bvec->bv_len;
366 }
367 if (page) {
368 kunmap(page);
369 __free_page(page);
370 }
371out:
372 return ret;
373fail:
374 printk(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
375 ret = -ENOMEM;
376 goto out;
377}
378
379struct lo_read_data {
380 struct loop_device *lo;
381 struct page *page;
382 unsigned offset;
383 int bsize;
384};
385
386static int
387lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
388 struct splice_desc *sd)
389{
390 struct lo_read_data *p = sd->u.data;
391 struct loop_device *lo = p->lo;
392 struct page *page = buf->page;
393 sector_t IV;
394 int size, ret;
395
396 ret = buf->ops->confirm(pipe, buf);
397 if (unlikely(ret))
398 return ret;
399
400 IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) +
401 (buf->offset >> 9);
402 size = sd->len;
403 if (size > p->bsize)
404 size = p->bsize;
405
406 if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) {
407 printk(KERN_ERR "loop: transfer error block %ld\n",
408 page->index);
409 size = -EINVAL;
410 }
411
412 flush_dcache_page(p->page);
413
414 if (size > 0)
415 p->offset += size;
416
417 return size;
418}
419
420static int
421lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd)
422{
423 return __splice_from_pipe(pipe, sd, lo_splice_actor);
424}
425
426static int
427do_lo_receive(struct loop_device *lo,
428 struct bio_vec *bvec, int bsize, loff_t pos)
429{
430 struct lo_read_data cookie;
431 struct splice_desc sd;
432 struct file *file;
433 long retval;
434
435 cookie.lo = lo;
436 cookie.page = bvec->bv_page;
437 cookie.offset = bvec->bv_offset;
438 cookie.bsize = bsize;
439
440 sd.len = 0;
441 sd.total_len = bvec->bv_len;
442 sd.flags = 0;
443 sd.pos = pos;
444 sd.u.data = &cookie;
445
446 file = lo->lo_backing_file;
447 retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);
448
449 if (retval < 0)
450 return retval;
451
452 return 0;
453}
454
455static int
456lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos)
457{
458 struct bio_vec *bvec;
459 int i, ret = 0;
460
461 bio_for_each_segment(bvec, bio, i) {
462 ret = do_lo_receive(lo, bvec, bsize, pos);
463 if (ret < 0)
464 break;
465 pos += bvec->bv_len;
466 }
467 return ret;
468}
469
470static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
471{
472 loff_t pos;
473 int ret;
474
475 pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
476
477 if (bio_rw(bio) == WRITE) {
478 bool barrier = bio_rw_flagged(bio, BIO_RW_BARRIER);
479 struct file *file = lo->lo_backing_file;
480
481 if (barrier) {
482 if (unlikely(!file->f_op->fsync)) {
483 ret = -EOPNOTSUPP;
484 goto out;
485 }
486
487 ret = vfs_fsync(file, file->f_path.dentry, 0);
488 if (unlikely(ret)) {
489 ret = -EIO;
490 goto out;
491 }
492 }
493
494 ret = lo_send(lo, bio, pos);
495
496 if (barrier && !ret) {
497 ret = vfs_fsync(file, file->f_path.dentry, 0);
498 if (unlikely(ret))
499 ret = -EIO;
500 }
501 } else
502 ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
503
504out:
505 return ret;
506}
507
508/*
509 * Add bio to back of pending list
510 */
511static void loop_add_bio(struct loop_device *lo, struct bio *bio)
512{
513 bio_list_add(&lo->lo_bio_list, bio);
514}
515
516/*
517 * Grab first pending buffer
518 */
519static struct bio *loop_get_bio(struct loop_device *lo)
520{
521 return bio_list_pop(&lo->lo_bio_list);
522}
523
524static int loop_make_request(struct request_queue *q, struct bio *old_bio)
525{
526 struct loop_device *lo = q->queuedata;
527 int rw = bio_rw(old_bio);
528
529 if (rw == READA)
530 rw = READ;
531
532 BUG_ON(!lo || (rw != READ && rw != WRITE));
533
534 spin_lock_irq(&lo->lo_lock);
535 if (lo->lo_state != Lo_bound)
536 goto out;
537 if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))
538 goto out;
539 loop_add_bio(lo, old_bio);
540 wake_up(&lo->lo_event);
541 spin_unlock_irq(&lo->lo_lock);
542 return 0;
543
544out:
545 spin_unlock_irq(&lo->lo_lock);
546 bio_io_error(old_bio);
547 return 0;
548}
549
550/*
551 * kick off io on the underlying address space
552 */
553static void loop_unplug(struct request_queue *q)
554{
555 struct loop_device *lo = q->queuedata;
556
557 queue_flag_clear_unlocked(QUEUE_FLAG_PLUGGED, q);
558 blk_run_address_space(lo->lo_backing_file->f_mapping);
559}
560
561struct switch_request {
562 struct file *file;
563 struct completion wait;
564};
565
566static void do_loop_switch(struct loop_device *, struct switch_request *);
567
568static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio)
569{
570 if (unlikely(!bio->bi_bdev)) {
571 do_loop_switch(lo, bio->bi_private);
572 bio_put(bio);
573 } else {
574 int ret = do_bio_filebacked(lo, bio);
575 bio_endio(bio, ret);
576 }
577}
578
579/*
580 * worker thread that handles reads/writes to file backed loop devices,
581 * to avoid blocking in our make_request_fn. it also does loop decrypting
582 * on reads for block backed loop, as that is too heavy to do from
583 * b_end_io context where irqs may be disabled.
584 *
585 * Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before
586 * calling kthread_stop(). Therefore once kthread_should_stop() is
587 * true, make_request will not place any more requests. Therefore
588 * once kthread_should_stop() is true and lo_bio is NULL, we are
589 * done with the loop.
590 */
591static int loop_thread(void *data)
592{
593 struct loop_device *lo = data;
594 struct bio *bio;
595
596 set_user_nice(current, -20);
597
598 while (!kthread_should_stop() || !bio_list_empty(&lo->lo_bio_list)) {
599
600 wait_event_interruptible(lo->lo_event,
601 !bio_list_empty(&lo->lo_bio_list) ||
602 kthread_should_stop());
603
604 if (bio_list_empty(&lo->lo_bio_list))
605 continue;
606 spin_lock_irq(&lo->lo_lock);
607 bio = loop_get_bio(lo);
608 spin_unlock_irq(&lo->lo_lock);
609
610 BUG_ON(!bio);
611 loop_handle_bio(lo, bio);
612 }
613
614 return 0;
615}
616
617/*
618 * loop_switch performs the hard work of switching a backing store.
619 * First it needs to flush existing IO, it does this by sending a magic
620 * BIO down the pipe. The completion of this BIO does the actual switch.
621 */
622static int loop_switch(struct loop_device *lo, struct file *file)
623{
624 struct switch_request w;
625 struct bio *bio = bio_alloc(GFP_KERNEL, 0);
626 if (!bio)
627 return -ENOMEM;
628 init_completion(&w.wait);
629 w.file = file;
630 bio->bi_private = &w;
631 bio->bi_bdev = NULL;
632 loop_make_request(lo->lo_queue, bio);
633 wait_for_completion(&w.wait);
634 return 0;
635}
636
637/*
638 * Helper to flush the IOs in loop, but keeping loop thread running
639 */
640static int loop_flush(struct loop_device *lo)
641{
642 /* loop not yet configured, no running thread, nothing to flush */
643 if (!lo->lo_thread)
644 return 0;
645
646 return loop_switch(lo, NULL);
647}
648
649/*
650 * Do the actual switch; called from the BIO completion routine
651 */
652static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
653{
654 struct file *file = p->file;
655 struct file *old_file = lo->lo_backing_file;
656 struct address_space *mapping;
657
658 /* if no new file, only flush of queued bios requested */
659 if (!file)
660 goto out;
661
662 mapping = file->f_mapping;
663 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
664 lo->lo_backing_file = file;
665 lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
666 mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
667 lo->old_gfp_mask = mapping_gfp_mask(mapping);
668 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
669out:
670 complete(&p->wait);
671}
672
673
674/*
675 * loop_change_fd switched the backing store of a loopback device to
676 * a new file. This is useful for operating system installers to free up
677 * the original file and in High Availability environments to switch to
678 * an alternative location for the content in case of server meltdown.
679 * This can only work if the loop device is used read-only, and if the
680 * new backing store is the same size and type as the old backing store.
681 */
682static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
683 unsigned int arg)
684{
685 struct file *file, *old_file;
686 struct inode *inode;
687 int error;
688
689 error = -ENXIO;
690 if (lo->lo_state != Lo_bound)
691 goto out;
692
693 /* the loop device has to be read-only */
694 error = -EINVAL;
695 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
696 goto out;
697
698 error = -EBADF;
699 file = fget(arg);
700 if (!file)
701 goto out;
702
703 inode = file->f_mapping->host;
704 old_file = lo->lo_backing_file;
705
706 error = -EINVAL;
707
708 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
709 goto out_putf;
710
711 /* size of the new backing store needs to be the same */
712 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
713 goto out_putf;
714
715 /* and ... switch */
716 error = loop_switch(lo, file);
717 if (error)
718 goto out_putf;
719
720 fput(old_file);
721 if (max_part > 0)
722 ioctl_by_bdev(bdev, BLKRRPART, 0);
723 return 0;
724
725 out_putf:
726 fput(file);
727 out:
728 return error;
729}
730
731static inline int is_loop_device(struct file *file)
732{
733 struct inode *i = file->f_mapping->host;
734
735 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
736}
737
738static int loop_set_fd(struct loop_device *lo, fmode_t mode,
739 struct block_device *bdev, unsigned int arg)
740{
741 struct file *file, *f;
742 struct inode *inode;
743 struct address_space *mapping;
744 unsigned lo_blocksize;
745 int lo_flags = 0;
746 int error;
747 loff_t size;
748
749 /* This is safe, since we have a reference from open(). */
750 __module_get(THIS_MODULE);
751
752 error = -EBADF;
753 file = fget(arg);
754 if (!file)
755 goto out;
756
757 error = -EBUSY;
758 if (lo->lo_state != Lo_unbound)
759 goto out_putf;
760
761 /* Avoid recursion */
762 f = file;
763 while (is_loop_device(f)) {
764 struct loop_device *l;
765
766 if (f->f_mapping->host->i_bdev == bdev)
767 goto out_putf;
768
769 l = f->f_mapping->host->i_bdev->bd_disk->private_data;
770 if (l->lo_state == Lo_unbound) {
771 error = -EINVAL;
772 goto out_putf;
773 }
774 f = l->lo_backing_file;
775 }
776
777 mapping = file->f_mapping;
778 inode = mapping->host;
779
780 if (!(file->f_mode & FMODE_WRITE))
781 lo_flags |= LO_FLAGS_READ_ONLY;
782
783 error = -EINVAL;
784 if (S_ISREG(inode->i_mode) || S_ISBLK(inode->i_mode)) {
785 const struct address_space_operations *aops = mapping->a_ops;
786
787 if (aops->write_begin)
788 lo_flags |= LO_FLAGS_USE_AOPS;
789 if (!(lo_flags & LO_FLAGS_USE_AOPS) && !file->f_op->write)
790 lo_flags |= LO_FLAGS_READ_ONLY;
791
792 lo_blocksize = S_ISBLK(inode->i_mode) ?
793 inode->i_bdev->bd_block_size : PAGE_SIZE;
794
795 error = 0;
796 } else {
797 goto out_putf;
798 }
799
800 size = get_loop_size(lo, file);
801
802 if ((loff_t)(sector_t)size != size) {
803 error = -EFBIG;
804 goto out_putf;
805 }
806
807 if (!(mode & FMODE_WRITE))
808 lo_flags |= LO_FLAGS_READ_ONLY;
809
810 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
811
812 lo->lo_blocksize = lo_blocksize;
813 lo->lo_device = bdev;
814 lo->lo_flags = lo_flags;
815 lo->lo_backing_file = file;
816 lo->transfer = transfer_none;
817 lo->ioctl = NULL;
818 lo->lo_sizelimit = 0;
819 lo->old_gfp_mask = mapping_gfp_mask(mapping);
820 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
821
822 bio_list_init(&lo->lo_bio_list);
823
824 /*
825 * set queue make_request_fn, and add limits based on lower level
826 * device
827 */
828 blk_queue_make_request(lo->lo_queue, loop_make_request);
829 lo->lo_queue->queuedata = lo;
830 lo->lo_queue->unplug_fn = loop_unplug;
831
832 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
833 blk_queue_ordered(lo->lo_queue, QUEUE_ORDERED_DRAIN, NULL);
834
835 set_capacity(lo->lo_disk, size);
836 bd_set_size(bdev, size << 9);
837
838 set_blocksize(bdev, lo_blocksize);
839
840 lo->lo_thread = kthread_create(loop_thread, lo, "loop%d",
841 lo->lo_number);
842 if (IS_ERR(lo->lo_thread)) {
843 error = PTR_ERR(lo->lo_thread);
844 goto out_clr;
845 }
846 lo->lo_state = Lo_bound;
847 wake_up_process(lo->lo_thread);
848 if (max_part > 0)
849 ioctl_by_bdev(bdev, BLKRRPART, 0);
850 return 0;
851
852out_clr:
853 lo->lo_thread = NULL;
854 lo->lo_device = NULL;
855 lo->lo_backing_file = NULL;
856 lo->lo_flags = 0;
857 set_capacity(lo->lo_disk, 0);
858 invalidate_bdev(bdev);
859 bd_set_size(bdev, 0);
860 mapping_set_gfp_mask(mapping, lo->old_gfp_mask);
861 lo->lo_state = Lo_unbound;
862 out_putf:
863 fput(file);
864 out:
865 /* This is safe: open() is still holding a reference. */
866 module_put(THIS_MODULE);
867 return error;
868}
869
870static int
871loop_release_xfer(struct loop_device *lo)
872{
873 int err = 0;
874 struct loop_func_table *xfer = lo->lo_encryption;
875
876 if (xfer) {
877 if (xfer->release)
878 err = xfer->release(lo);
879 lo->transfer = NULL;
880 lo->lo_encryption = NULL;
881 module_put(xfer->owner);
882 }
883 return err;
884}
885
886static int
887loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
888 const struct loop_info64 *i)
889{
890 int err = 0;
891
892 if (xfer) {
893 struct module *owner = xfer->owner;
894
895 if (!try_module_get(owner))
896 return -EINVAL;
897 if (xfer->init)
898 err = xfer->init(lo, i);
899 if (err)
900 module_put(owner);
901 else
902 lo->lo_encryption = xfer;
903 }
904 return err;
905}
906
907static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)
908{
909 struct file *filp = lo->lo_backing_file;
910 gfp_t gfp = lo->old_gfp_mask;
911
912 if (lo->lo_state != Lo_bound)
913 return -ENXIO;
914
915 if (lo->lo_refcnt > 1) /* we needed one fd for the ioctl */
916 return -EBUSY;
917
918 if (filp == NULL)
919 return -EINVAL;
920
921 spin_lock_irq(&lo->lo_lock);
922 lo->lo_state = Lo_rundown;
923 spin_unlock_irq(&lo->lo_lock);
924
925 kthread_stop(lo->lo_thread);
926
927 lo->lo_queue->unplug_fn = NULL;
928 lo->lo_backing_file = NULL;
929
930 loop_release_xfer(lo);
931 lo->transfer = NULL;
932 lo->ioctl = NULL;
933 lo->lo_device = NULL;
934 lo->lo_encryption = NULL;
935 lo->lo_offset = 0;
936 lo->lo_sizelimit = 0;
937 lo->lo_encrypt_key_size = 0;
938 lo->lo_flags = 0;
939 lo->lo_thread = NULL;
940 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
941 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
942 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
943 if (bdev)
944 invalidate_bdev(bdev);
945 set_capacity(lo->lo_disk, 0);
946 if (bdev)
947 bd_set_size(bdev, 0);
948 mapping_set_gfp_mask(filp->f_mapping, gfp);
949 lo->lo_state = Lo_unbound;
950 /* This is safe: open() is still holding a reference. */
951 module_put(THIS_MODULE);
952 if (max_part > 0 && bdev)
953 ioctl_by_bdev(bdev, BLKRRPART, 0);
954 mutex_unlock(&lo->lo_ctl_mutex);
955 /*
956 * Need not hold lo_ctl_mutex to fput backing file.
957 * Calling fput holding lo_ctl_mutex triggers a circular
958 * lock dependency possibility warning as fput can take
959 * bd_mutex which is usually taken before lo_ctl_mutex.
960 */
961 fput(filp);
962 return 0;
963}
964
965static int
966loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
967{
968 int err;
969 struct loop_func_table *xfer;
970 uid_t uid = current_uid();
971
972 if (lo->lo_encrypt_key_size &&
973 lo->lo_key_owner != uid &&
974 !capable(CAP_SYS_ADMIN))
975 return -EPERM;
976 if (lo->lo_state != Lo_bound)
977 return -ENXIO;
978 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
979 return -EINVAL;
980
981 err = loop_release_xfer(lo);
982 if (err)
983 return err;
984
985 if (info->lo_encrypt_type) {
986 unsigned int type = info->lo_encrypt_type;
987
988 if (type >= MAX_LO_CRYPT)
989 return -EINVAL;
990 xfer = xfer_funcs[type];
991 if (xfer == NULL)
992 return -EINVAL;
993 } else
994 xfer = NULL;
995
996 err = loop_init_xfer(lo, xfer, info);
997 if (err)
998 return err;
999
1000 if (lo->lo_offset != info->lo_offset ||
1001 lo->lo_sizelimit != info->lo_sizelimit) {
1002 lo->lo_offset = info->lo_offset;
1003 lo->lo_sizelimit = info->lo_sizelimit;
1004 if (figure_loop_size(lo))
1005 return -EFBIG;
1006 }
1007
1008 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
1009 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
1010 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
1011 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
1012
1013 if (!xfer)
1014 xfer = &none_funcs;
1015 lo->transfer = xfer->transfer;
1016 lo->ioctl = xfer->ioctl;
1017
1018 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
1019 (info->lo_flags & LO_FLAGS_AUTOCLEAR))
1020 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
1021
1022 lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
1023 lo->lo_init[0] = info->lo_init[0];
1024 lo->lo_init[1] = info->lo_init[1];
1025 if (info->lo_encrypt_key_size) {
1026 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
1027 info->lo_encrypt_key_size);
1028 lo->lo_key_owner = uid;
1029 }
1030
1031 return 0;
1032}
1033
1034static int
1035loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1036{
1037 struct file *file = lo->lo_backing_file;
1038 struct kstat stat;
1039 int error;
1040
1041 if (lo->lo_state != Lo_bound)
1042 return -ENXIO;
1043 error = vfs_getattr(file->f_path.mnt, file->f_path.dentry, &stat);
1044 if (error)
1045 return error;
1046 memset(info, 0, sizeof(*info));
1047 info->lo_number = lo->lo_number;
1048 info->lo_device = huge_encode_dev(stat.dev);
1049 info->lo_inode = stat.ino;
1050 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
1051 info->lo_offset = lo->lo_offset;
1052 info->lo_sizelimit = lo->lo_sizelimit;
1053 info->lo_flags = lo->lo_flags;
1054 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1055 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1056 info->lo_encrypt_type =
1057 lo->lo_encryption ? lo->lo_encryption->number : 0;
1058 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1059 info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1060 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1061 lo->lo_encrypt_key_size);
1062 }
1063 return 0;
1064}
1065
1066static void
1067loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1068{
1069 memset(info64, 0, sizeof(*info64));
1070 info64->lo_number = info->lo_number;
1071 info64->lo_device = info->lo_device;
1072 info64->lo_inode = info->lo_inode;
1073 info64->lo_rdevice = info->lo_rdevice;
1074 info64->lo_offset = info->lo_offset;
1075 info64->lo_sizelimit = 0;
1076 info64->lo_encrypt_type = info->lo_encrypt_type;
1077 info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1078 info64->lo_flags = info->lo_flags;
1079 info64->lo_init[0] = info->lo_init[0];
1080 info64->lo_init[1] = info->lo_init[1];
1081 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1082 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1083 else
1084 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1085 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1086}
1087
1088static int
1089loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1090{
1091 memset(info, 0, sizeof(*info));
1092 info->lo_number = info64->lo_number;
1093 info->lo_device = info64->lo_device;
1094 info->lo_inode = info64->lo_inode;
1095 info->lo_rdevice = info64->lo_rdevice;
1096 info->lo_offset = info64->lo_offset;
1097 info->lo_encrypt_type = info64->lo_encrypt_type;
1098 info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1099 info->lo_flags = info64->lo_flags;
1100 info->lo_init[0] = info64->lo_init[0];
1101 info->lo_init[1] = info64->lo_init[1];
1102 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1103 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1104 else
1105 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1106 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1107
1108 /* error in case values were truncated */
1109 if (info->lo_device != info64->lo_device ||
1110 info->lo_rdevice != info64->lo_rdevice ||
1111 info->lo_inode != info64->lo_inode ||
1112 info->lo_offset != info64->lo_offset)
1113 return -EOVERFLOW;
1114
1115 return 0;
1116}
1117
1118static int
1119loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1120{
1121 struct loop_info info;
1122 struct loop_info64 info64;
1123
1124 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1125 return -EFAULT;
1126 loop_info64_from_old(&info, &info64);
1127 return loop_set_status(lo, &info64);
1128}
1129
1130static int
1131loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1132{
1133 struct loop_info64 info64;
1134
1135 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1136 return -EFAULT;
1137 return loop_set_status(lo, &info64);
1138}
1139
1140static int
1141loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1142 struct loop_info info;
1143 struct loop_info64 info64;
1144 int err = 0;
1145
1146 if (!arg)
1147 err = -EINVAL;
1148 if (!err)
1149 err = loop_get_status(lo, &info64);
1150 if (!err)
1151 err = loop_info64_to_old(&info64, &info);
1152 if (!err && copy_to_user(arg, &info, sizeof(info)))
1153 err = -EFAULT;
1154
1155 return err;
1156}
1157
1158static int
1159loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1160 struct loop_info64 info64;
1161 int err = 0;
1162
1163 if (!arg)
1164 err = -EINVAL;
1165 if (!err)
1166 err = loop_get_status(lo, &info64);
1167 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1168 err = -EFAULT;
1169
1170 return err;
1171}
1172
1173static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
1174{
1175 int err;
1176 sector_t sec;
1177 loff_t sz;
1178
1179 err = -ENXIO;
1180 if (unlikely(lo->lo_state != Lo_bound))
1181 goto out;
1182 err = figure_loop_size(lo);
1183 if (unlikely(err))
1184 goto out;
1185 sec = get_capacity(lo->lo_disk);
1186 /* the width of sector_t may be narrow for bit-shift */
1187 sz = sec;
1188 sz <<= 9;
1189 mutex_lock(&bdev->bd_mutex);
1190 bd_set_size(bdev, sz);
1191 mutex_unlock(&bdev->bd_mutex);
1192
1193 out:
1194 return err;
1195}
1196
1197static int lo_ioctl(struct block_device *bdev, fmode_t mode,
1198 unsigned int cmd, unsigned long arg)
1199{
1200 struct loop_device *lo = bdev->bd_disk->private_data;
1201 int err;
1202
1203 mutex_lock_nested(&lo->lo_ctl_mutex, 1);
1204 switch (cmd) {
1205 case LOOP_SET_FD:
1206 err = loop_set_fd(lo, mode, bdev, arg);
1207 break;
1208 case LOOP_CHANGE_FD:
1209 err = loop_change_fd(lo, bdev, arg);
1210 break;
1211 case LOOP_CLR_FD:
1212 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1213 err = loop_clr_fd(lo, bdev);
1214 if (!err)
1215 goto out_unlocked;
1216 break;
1217 case LOOP_SET_STATUS:
1218 err = loop_set_status_old(lo, (struct loop_info __user *) arg);
1219 break;
1220 case LOOP_GET_STATUS:
1221 err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1222 break;
1223 case LOOP_SET_STATUS64:
1224 err = loop_set_status64(lo, (struct loop_info64 __user *) arg);
1225 break;
1226 case LOOP_GET_STATUS64:
1227 err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1228 break;
1229 case LOOP_SET_CAPACITY:
1230 err = -EPERM;
1231 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1232 err = loop_set_capacity(lo, bdev);
1233 break;
1234 default:
1235 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1236 }
1237 mutex_unlock(&lo->lo_ctl_mutex);
1238
1239out_unlocked:
1240 return err;
1241}
1242
1243#ifdef CONFIG_COMPAT
1244struct compat_loop_info {
1245 compat_int_t lo_number; /* ioctl r/o */
1246 compat_dev_t lo_device; /* ioctl r/o */
1247 compat_ulong_t lo_inode; /* ioctl r/o */
1248 compat_dev_t lo_rdevice; /* ioctl r/o */
1249 compat_int_t lo_offset;
1250 compat_int_t lo_encrypt_type;
1251 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1252 compat_int_t lo_flags; /* ioctl r/o */
1253 char lo_name[LO_NAME_SIZE];
1254 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1255 compat_ulong_t lo_init[2];
1256 char reserved[4];
1257};
1258
1259/*
1260 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1261 * - noinlined to reduce stack space usage in main part of driver
1262 */
1263static noinline int
1264loop_info64_from_compat(const struct compat_loop_info __user *arg,
1265 struct loop_info64 *info64)
1266{
1267 struct compat_loop_info info;
1268
1269 if (copy_from_user(&info, arg, sizeof(info)))
1270 return -EFAULT;
1271
1272 memset(info64, 0, sizeof(*info64));
1273 info64->lo_number = info.lo_number;
1274 info64->lo_device = info.lo_device;
1275 info64->lo_inode = info.lo_inode;
1276 info64->lo_rdevice = info.lo_rdevice;
1277 info64->lo_offset = info.lo_offset;
1278 info64->lo_sizelimit = 0;
1279 info64->lo_encrypt_type = info.lo_encrypt_type;
1280 info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1281 info64->lo_flags = info.lo_flags;
1282 info64->lo_init[0] = info.lo_init[0];
1283 info64->lo_init[1] = info.lo_init[1];
1284 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1285 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1286 else
1287 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1288 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1289 return 0;
1290}
1291
1292/*
1293 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1294 * - noinlined to reduce stack space usage in main part of driver
1295 */
1296static noinline int
1297loop_info64_to_compat(const struct loop_info64 *info64,
1298 struct compat_loop_info __user *arg)
1299{
1300 struct compat_loop_info info;
1301
1302 memset(&info, 0, sizeof(info));
1303 info.lo_number = info64->lo_number;
1304 info.lo_device = info64->lo_device;
1305 info.lo_inode = info64->lo_inode;
1306 info.lo_rdevice = info64->lo_rdevice;
1307 info.lo_offset = info64->lo_offset;
1308 info.lo_encrypt_type = info64->lo_encrypt_type;
1309 info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
1310 info.lo_flags = info64->lo_flags;
1311 info.lo_init[0] = info64->lo_init[0];
1312 info.lo_init[1] = info64->lo_init[1];
1313 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1314 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1315 else
1316 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1317 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1318
1319 /* error in case values were truncated */
1320 if (info.lo_device != info64->lo_device ||
1321 info.lo_rdevice != info64->lo_rdevice ||
1322 info.lo_inode != info64->lo_inode ||
1323 info.lo_offset != info64->lo_offset ||
1324 info.lo_init[0] != info64->lo_init[0] ||
1325 info.lo_init[1] != info64->lo_init[1])
1326 return -EOVERFLOW;
1327
1328 if (copy_to_user(arg, &info, sizeof(info)))
1329 return -EFAULT;
1330 return 0;
1331}
1332
1333static int
1334loop_set_status_compat(struct loop_device *lo,
1335 const struct compat_loop_info __user *arg)
1336{
1337 struct loop_info64 info64;
1338 int ret;
1339
1340 ret = loop_info64_from_compat(arg, &info64);
1341 if (ret < 0)
1342 return ret;
1343 return loop_set_status(lo, &info64);
1344}
1345
1346static int
1347loop_get_status_compat(struct loop_device *lo,
1348 struct compat_loop_info __user *arg)
1349{
1350 struct loop_info64 info64;
1351 int err = 0;
1352
1353 if (!arg)
1354 err = -EINVAL;
1355 if (!err)
1356 err = loop_get_status(lo, &info64);
1357 if (!err)
1358 err = loop_info64_to_compat(&info64, arg);
1359 return err;
1360}
1361
1362static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1363 unsigned int cmd, unsigned long arg)
1364{
1365 struct loop_device *lo = bdev->bd_disk->private_data;
1366 int err;
1367
1368 switch(cmd) {
1369 case LOOP_SET_STATUS:
1370 mutex_lock(&lo->lo_ctl_mutex);
1371 err = loop_set_status_compat(
1372 lo, (const struct compat_loop_info __user *) arg);
1373 mutex_unlock(&lo->lo_ctl_mutex);
1374 break;
1375 case LOOP_GET_STATUS:
1376 mutex_lock(&lo->lo_ctl_mutex);
1377 err = loop_get_status_compat(
1378 lo, (struct compat_loop_info __user *) arg);
1379 mutex_unlock(&lo->lo_ctl_mutex);
1380 break;
1381 case LOOP_SET_CAPACITY:
1382 case LOOP_CLR_FD:
1383 case LOOP_GET_STATUS64:
1384 case LOOP_SET_STATUS64:
1385 arg = (unsigned long) compat_ptr(arg);
1386 case LOOP_SET_FD:
1387 case LOOP_CHANGE_FD:
1388 err = lo_ioctl(bdev, mode, cmd, arg);
1389 break;
1390 default:
1391 err = -ENOIOCTLCMD;
1392 break;
1393 }
1394 return err;
1395}
1396#endif
1397
1398static int lo_open(struct block_device *bdev, fmode_t mode)
1399{
1400 struct loop_device *lo = bdev->bd_disk->private_data;
1401
1402 mutex_lock(&lo->lo_ctl_mutex);
1403 lo->lo_refcnt++;
1404 mutex_unlock(&lo->lo_ctl_mutex);
1405
1406 return 0;
1407}
1408
1409static int lo_release(struct gendisk *disk, fmode_t mode)
1410{
1411 struct loop_device *lo = disk->private_data;
1412 int err;
1413
1414 mutex_lock(&lo->lo_ctl_mutex);
1415
1416 if (--lo->lo_refcnt)
1417 goto out;
1418
1419 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
1420 /*
1421 * In autoclear mode, stop the loop thread
1422 * and remove configuration after last close.
1423 */
1424 err = loop_clr_fd(lo, NULL);
1425 if (!err)
1426 goto out_unlocked;
1427 } else {
1428 /*
1429 * Otherwise keep thread (if running) and config,
1430 * but flush possible ongoing bios in thread.
1431 */
1432 loop_flush(lo);
1433 }
1434
1435out:
1436 mutex_unlock(&lo->lo_ctl_mutex);
1437out_unlocked:
1438 return 0;
1439}
1440
1441static const struct block_device_operations lo_fops = {
1442 .owner = THIS_MODULE,
1443 .open = lo_open,
1444 .release = lo_release,
1445 .ioctl = lo_ioctl,
1446#ifdef CONFIG_COMPAT
1447 .compat_ioctl = lo_compat_ioctl,
1448#endif
1449};
1450
1451/*
1452 * And now the modules code and kernel interface.
1453 */
1454static int max_loop;
1455module_param(max_loop, int, 0);
1456MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1457module_param(max_part, int, 0);
1458MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1459MODULE_LICENSE("GPL");
1460MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1461
1462int loop_register_transfer(struct loop_func_table *funcs)
1463{
1464 unsigned int n = funcs->number;
1465
1466 if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1467 return -EINVAL;
1468 xfer_funcs[n] = funcs;
1469 return 0;
1470}
1471
1472int loop_unregister_transfer(int number)
1473{
1474 unsigned int n = number;
1475 struct loop_device *lo;
1476 struct loop_func_table *xfer;
1477
1478 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1479 return -EINVAL;
1480
1481 xfer_funcs[n] = NULL;
1482
1483 list_for_each_entry(lo, &loop_devices, lo_list) {
1484 mutex_lock(&lo->lo_ctl_mutex);
1485
1486 if (lo->lo_encryption == xfer)
1487 loop_release_xfer(lo);
1488
1489 mutex_unlock(&lo->lo_ctl_mutex);
1490 }
1491
1492 return 0;
1493}
1494
1495EXPORT_SYMBOL(loop_register_transfer);
1496EXPORT_SYMBOL(loop_unregister_transfer);
1497
1498static struct loop_device *loop_alloc(int i)
1499{
1500 struct loop_device *lo;
1501 struct gendisk *disk;
1502
1503 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1504 if (!lo)
1505 goto out;
1506
1507 lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
1508 if (!lo->lo_queue)
1509 goto out_free_dev;
1510
1511 disk = lo->lo_disk = alloc_disk(1 << part_shift);
1512 if (!disk)
1513 goto out_free_queue;
1514
1515 mutex_init(&lo->lo_ctl_mutex);
1516 lo->lo_number = i;
1517 lo->lo_thread = NULL;
1518 init_waitqueue_head(&lo->lo_event);
1519 spin_lock_init(&lo->lo_lock);
1520 disk->major = LOOP_MAJOR;
1521 disk->first_minor = i << part_shift;
1522 disk->fops = &lo_fops;
1523 disk->private_data = lo;
1524 disk->queue = lo->lo_queue;
1525 sprintf(disk->disk_name, "loop%d", i);
1526 return lo;
1527
1528out_free_queue:
1529 blk_cleanup_queue(lo->lo_queue);
1530out_free_dev:
1531 kfree(lo);
1532out:
1533 return NULL;
1534}
1535
1536static void loop_free(struct loop_device *lo)
1537{
1538 blk_cleanup_queue(lo->lo_queue);
1539 put_disk(lo->lo_disk);
1540 list_del(&lo->lo_list);
1541 kfree(lo);
1542}
1543
1544static struct loop_device *loop_init_one(int i)
1545{
1546 struct loop_device *lo;
1547
1548 list_for_each_entry(lo, &loop_devices, lo_list) {
1549 if (lo->lo_number == i)
1550 return lo;
1551 }
1552
1553 lo = loop_alloc(i);
1554 if (lo) {
1555 add_disk(lo->lo_disk);
1556 list_add_tail(&lo->lo_list, &loop_devices);
1557 }
1558 return lo;
1559}
1560
1561static void loop_del_one(struct loop_device *lo)
1562{
1563 del_gendisk(lo->lo_disk);
1564 loop_free(lo);
1565}
1566
1567static struct kobject *loop_probe(dev_t dev, int *part, void *data)
1568{
1569 struct loop_device *lo;
1570 struct kobject *kobj;
1571
1572 mutex_lock(&loop_devices_mutex);
1573 lo = loop_init_one(dev & MINORMASK);
1574 kobj = lo ? get_disk(lo->lo_disk) : ERR_PTR(-ENOMEM);
1575 mutex_unlock(&loop_devices_mutex);
1576
1577 *part = 0;
1578 return kobj;
1579}
1580
1581static int __init loop_init(void)
1582{
1583 int i, nr;
1584 unsigned long range;
1585 struct loop_device *lo, *next;
1586
1587 /*
1588 * loop module now has a feature to instantiate underlying device
1589 * structure on-demand, provided that there is an access dev node.
1590 * However, this will not work well with user space tool that doesn't
1591 * know about such "feature". In order to not break any existing
1592 * tool, we do the following:
1593 *
1594 * (1) if max_loop is specified, create that many upfront, and this
1595 * also becomes a hard limit.
1596 * (2) if max_loop is not specified, create 8 loop device on module
1597 * load, user can further extend loop device by create dev node
1598 * themselves and have kernel automatically instantiate actual
1599 * device on-demand.
1600 */
1601
1602 part_shift = 0;
1603 if (max_part > 0)
1604 part_shift = fls(max_part);
1605
1606 if (max_loop > 1UL << (MINORBITS - part_shift))
1607 return -EINVAL;
1608
1609 if (max_loop) {
1610 nr = max_loop;
1611 range = max_loop;
1612 } else {
1613 nr = 8;
1614 range = 1UL << (MINORBITS - part_shift);
1615 }
1616
1617 if (register_blkdev(LOOP_MAJOR, "loop"))
1618 return -EIO;
1619
1620 for (i = 0; i < nr; i++) {
1621 lo = loop_alloc(i);
1622 if (!lo)
1623 goto Enomem;
1624 list_add_tail(&lo->lo_list, &loop_devices);
1625 }
1626
1627 /* point of no return */
1628
1629 list_for_each_entry(lo, &loop_devices, lo_list)
1630 add_disk(lo->lo_disk);
1631
1632 blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
1633 THIS_MODULE, loop_probe, NULL, NULL);
1634
1635 printk(KERN_INFO "loop: module loaded\n");
1636 return 0;
1637
1638Enomem:
1639 printk(KERN_INFO "loop: out of memory\n");
1640
1641 list_for_each_entry_safe(lo, next, &loop_devices, lo_list)
1642 loop_free(lo);
1643
1644 unregister_blkdev(LOOP_MAJOR, "loop");
1645 return -ENOMEM;
1646}
1647
1648static void __exit loop_exit(void)
1649{
1650 unsigned long range;
1651 struct loop_device *lo, *next;
1652
1653 range = max_loop ? max_loop : 1UL << (MINORBITS - part_shift);
1654
1655 list_for_each_entry_safe(lo, next, &loop_devices, lo_list)
1656 loop_del_one(lo);
1657
1658 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
1659 unregister_blkdev(LOOP_MAJOR, "loop");
1660}
1661
1662module_init(loop_init);
1663module_exit(loop_exit);
1664
1665#ifndef MODULE
1666static int __init max_loop_setup(char *str)
1667{
1668 max_loop = simple_strtol(str, NULL, 0);
1669 return 1;
1670}
1671
1672__setup("max_loop=", max_loop_setup);
1673#endif