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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. Bolsø, <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 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/compat.h>
67#include <linux/suspend.h>
68#include <linux/freezer.h>
69#include <linux/mutex.h>
70#include <linux/writeback.h>
71#include <linux/completion.h>
72#include <linux/highmem.h>
73#include <linux/kthread.h>
74#include <linux/splice.h>
75#include <linux/sysfs.h>
76#include <linux/miscdevice.h>
77#include <linux/falloc.h>
78#include "loop.h"
79
80#include <asm/uaccess.h>
81
82static DEFINE_IDR(loop_index_idr);
83static DEFINE_MUTEX(loop_index_mutex);
84
85static int max_part;
86static int part_shift;
87
88/*
89 * Transfer functions
90 */
91static int transfer_none(struct loop_device *lo, int cmd,
92 struct page *raw_page, unsigned raw_off,
93 struct page *loop_page, unsigned loop_off,
94 int size, sector_t real_block)
95{
96 char *raw_buf = kmap_atomic(raw_page) + raw_off;
97 char *loop_buf = kmap_atomic(loop_page) + loop_off;
98
99 if (cmd == READ)
100 memcpy(loop_buf, raw_buf, size);
101 else
102 memcpy(raw_buf, loop_buf, size);
103
104 kunmap_atomic(loop_buf);
105 kunmap_atomic(raw_buf);
106 cond_resched();
107 return 0;
108}
109
110static int transfer_xor(struct loop_device *lo, int cmd,
111 struct page *raw_page, unsigned raw_off,
112 struct page *loop_page, unsigned loop_off,
113 int size, sector_t real_block)
114{
115 char *raw_buf = kmap_atomic(raw_page) + raw_off;
116 char *loop_buf = kmap_atomic(loop_page) + loop_off;
117 char *in, *out, *key;
118 int i, keysize;
119
120 if (cmd == READ) {
121 in = raw_buf;
122 out = loop_buf;
123 } else {
124 in = loop_buf;
125 out = raw_buf;
126 }
127
128 key = lo->lo_encrypt_key;
129 keysize = lo->lo_encrypt_key_size;
130 for (i = 0; i < size; i++)
131 *out++ = *in++ ^ key[(i & 511) % keysize];
132
133 kunmap_atomic(loop_buf);
134 kunmap_atomic(raw_buf);
135 cond_resched();
136 return 0;
137}
138
139static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
140{
141 if (unlikely(info->lo_encrypt_key_size <= 0))
142 return -EINVAL;
143 return 0;
144}
145
146static struct loop_func_table none_funcs = {
147 .number = LO_CRYPT_NONE,
148 .transfer = transfer_none,
149};
150
151static struct loop_func_table xor_funcs = {
152 .number = LO_CRYPT_XOR,
153 .transfer = transfer_xor,
154 .init = xor_init
155};
156
157/* xfer_funcs[0] is special - its release function is never called */
158static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
159 &none_funcs,
160 &xor_funcs
161};
162
163static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
164{
165 loff_t loopsize;
166
167 /* Compute loopsize in bytes */
168 loopsize = i_size_read(file->f_mapping->host);
169 if (offset > 0)
170 loopsize -= offset;
171 /* offset is beyond i_size, weird but possible */
172 if (loopsize < 0)
173 return 0;
174
175 if (sizelimit > 0 && sizelimit < loopsize)
176 loopsize = sizelimit;
177 /*
178 * Unfortunately, if we want to do I/O on the device,
179 * the number of 512-byte sectors has to fit into a sector_t.
180 */
181 return loopsize >> 9;
182}
183
184static loff_t get_loop_size(struct loop_device *lo, struct file *file)
185{
186 return get_size(lo->lo_offset, lo->lo_sizelimit, file);
187}
188
189static int
190figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
191{
192 loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
193 sector_t x = (sector_t)size;
194 struct block_device *bdev = lo->lo_device;
195
196 if (unlikely((loff_t)x != size))
197 return -EFBIG;
198 if (lo->lo_offset != offset)
199 lo->lo_offset = offset;
200 if (lo->lo_sizelimit != sizelimit)
201 lo->lo_sizelimit = sizelimit;
202 set_capacity(lo->lo_disk, x);
203 bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
204 /* let user-space know about the new size */
205 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
206 return 0;
207}
208
209static inline int
210lo_do_transfer(struct loop_device *lo, int cmd,
211 struct page *rpage, unsigned roffs,
212 struct page *lpage, unsigned loffs,
213 int size, sector_t rblock)
214{
215 if (unlikely(!lo->transfer))
216 return 0;
217
218 return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
219}
220
221/**
222 * __do_lo_send_write - helper for writing data to a loop device
223 *
224 * This helper just factors out common code between do_lo_send_direct_write()
225 * and do_lo_send_write().
226 */
227static int __do_lo_send_write(struct file *file,
228 u8 *buf, const int len, loff_t pos)
229{
230 ssize_t bw;
231 mm_segment_t old_fs = get_fs();
232
233 file_start_write(file);
234 set_fs(get_ds());
235 bw = file->f_op->write(file, buf, len, &pos);
236 set_fs(old_fs);
237 file_end_write(file);
238 if (likely(bw == len))
239 return 0;
240 printk_ratelimited(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
241 (unsigned long long)pos, len);
242 if (bw >= 0)
243 bw = -EIO;
244 return bw;
245}
246
247/**
248 * do_lo_send_direct_write - helper for writing data to a loop device
249 *
250 * This is the fast, non-transforming version that does not need double
251 * buffering.
252 */
253static int do_lo_send_direct_write(struct loop_device *lo,
254 struct bio_vec *bvec, loff_t pos, struct page *page)
255{
256 ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
257 kmap(bvec->bv_page) + bvec->bv_offset,
258 bvec->bv_len, pos);
259 kunmap(bvec->bv_page);
260 cond_resched();
261 return bw;
262}
263
264/**
265 * do_lo_send_write - helper for writing data to a loop device
266 *
267 * This is the slow, transforming version that needs to double buffer the
268 * data as it cannot do the transformations in place without having direct
269 * access to the destination pages of the backing file.
270 */
271static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
272 loff_t pos, struct page *page)
273{
274 int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
275 bvec->bv_offset, bvec->bv_len, pos >> 9);
276 if (likely(!ret))
277 return __do_lo_send_write(lo->lo_backing_file,
278 page_address(page), bvec->bv_len,
279 pos);
280 printk_ratelimited(KERN_ERR "loop: Transfer error at byte offset %llu, "
281 "length %i.\n", (unsigned long long)pos, bvec->bv_len);
282 if (ret > 0)
283 ret = -EIO;
284 return ret;
285}
286
287static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos)
288{
289 int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t,
290 struct page *page);
291 struct bio_vec bvec;
292 struct bvec_iter iter;
293 struct page *page = NULL;
294 int ret = 0;
295
296 if (lo->transfer != transfer_none) {
297 page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
298 if (unlikely(!page))
299 goto fail;
300 kmap(page);
301 do_lo_send = do_lo_send_write;
302 } else {
303 do_lo_send = do_lo_send_direct_write;
304 }
305
306 bio_for_each_segment(bvec, bio, iter) {
307 ret = do_lo_send(lo, &bvec, pos, page);
308 if (ret < 0)
309 break;
310 pos += bvec.bv_len;
311 }
312 if (page) {
313 kunmap(page);
314 __free_page(page);
315 }
316out:
317 return ret;
318fail:
319 printk_ratelimited(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
320 ret = -ENOMEM;
321 goto out;
322}
323
324struct lo_read_data {
325 struct loop_device *lo;
326 struct page *page;
327 unsigned offset;
328 int bsize;
329};
330
331static int
332lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
333 struct splice_desc *sd)
334{
335 struct lo_read_data *p = sd->u.data;
336 struct loop_device *lo = p->lo;
337 struct page *page = buf->page;
338 sector_t IV;
339 int size;
340
341 IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) +
342 (buf->offset >> 9);
343 size = sd->len;
344 if (size > p->bsize)
345 size = p->bsize;
346
347 if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) {
348 printk_ratelimited(KERN_ERR "loop: transfer error block %ld\n",
349 page->index);
350 size = -EINVAL;
351 }
352
353 flush_dcache_page(p->page);
354
355 if (size > 0)
356 p->offset += size;
357
358 return size;
359}
360
361static int
362lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd)
363{
364 return __splice_from_pipe(pipe, sd, lo_splice_actor);
365}
366
367static ssize_t
368do_lo_receive(struct loop_device *lo,
369 struct bio_vec *bvec, int bsize, loff_t pos)
370{
371 struct lo_read_data cookie;
372 struct splice_desc sd;
373 struct file *file;
374 ssize_t retval;
375
376 cookie.lo = lo;
377 cookie.page = bvec->bv_page;
378 cookie.offset = bvec->bv_offset;
379 cookie.bsize = bsize;
380
381 sd.len = 0;
382 sd.total_len = bvec->bv_len;
383 sd.flags = 0;
384 sd.pos = pos;
385 sd.u.data = &cookie;
386
387 file = lo->lo_backing_file;
388 retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);
389
390 return retval;
391}
392
393static int
394lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos)
395{
396 struct bio_vec bvec;
397 struct bvec_iter iter;
398 ssize_t s;
399
400 bio_for_each_segment(bvec, bio, iter) {
401 s = do_lo_receive(lo, &bvec, bsize, pos);
402 if (s < 0)
403 return s;
404
405 if (s != bvec.bv_len) {
406 zero_fill_bio(bio);
407 break;
408 }
409 pos += bvec.bv_len;
410 }
411 return 0;
412}
413
414static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
415{
416 loff_t pos;
417 int ret;
418
419 pos = ((loff_t) bio->bi_iter.bi_sector << 9) + lo->lo_offset;
420
421 if (bio_rw(bio) == WRITE) {
422 struct file *file = lo->lo_backing_file;
423
424 if (bio->bi_rw & REQ_FLUSH) {
425 ret = vfs_fsync(file, 0);
426 if (unlikely(ret && ret != -EINVAL)) {
427 ret = -EIO;
428 goto out;
429 }
430 }
431
432 /*
433 * We use punch hole to reclaim the free space used by the
434 * image a.k.a. discard. However we do not support discard if
435 * encryption is enabled, because it may give an attacker
436 * useful information.
437 */
438 if (bio->bi_rw & REQ_DISCARD) {
439 struct file *file = lo->lo_backing_file;
440 int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
441
442 if ((!file->f_op->fallocate) ||
443 lo->lo_encrypt_key_size) {
444 ret = -EOPNOTSUPP;
445 goto out;
446 }
447 ret = file->f_op->fallocate(file, mode, pos,
448 bio->bi_iter.bi_size);
449 if (unlikely(ret && ret != -EINVAL &&
450 ret != -EOPNOTSUPP))
451 ret = -EIO;
452 goto out;
453 }
454
455 ret = lo_send(lo, bio, pos);
456
457 if ((bio->bi_rw & REQ_FUA) && !ret) {
458 ret = vfs_fsync(file, 0);
459 if (unlikely(ret && ret != -EINVAL))
460 ret = -EIO;
461 }
462 } else
463 ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
464
465out:
466 return ret;
467}
468
469/*
470 * Add bio to back of pending list
471 */
472static void loop_add_bio(struct loop_device *lo, struct bio *bio)
473{
474 lo->lo_bio_count++;
475 bio_list_add(&lo->lo_bio_list, bio);
476}
477
478/*
479 * Grab first pending buffer
480 */
481static struct bio *loop_get_bio(struct loop_device *lo)
482{
483 lo->lo_bio_count--;
484 return bio_list_pop(&lo->lo_bio_list);
485}
486
487static void loop_make_request(struct request_queue *q, struct bio *old_bio)
488{
489 struct loop_device *lo = q->queuedata;
490 int rw = bio_rw(old_bio);
491
492 if (rw == READA)
493 rw = READ;
494
495 BUG_ON(!lo || (rw != READ && rw != WRITE));
496
497 spin_lock_irq(&lo->lo_lock);
498 if (lo->lo_state != Lo_bound)
499 goto out;
500 if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))
501 goto out;
502 if (lo->lo_bio_count >= q->nr_congestion_on)
503 wait_event_lock_irq(lo->lo_req_wait,
504 lo->lo_bio_count < q->nr_congestion_off,
505 lo->lo_lock);
506 loop_add_bio(lo, old_bio);
507 wake_up(&lo->lo_event);
508 spin_unlock_irq(&lo->lo_lock);
509 return;
510
511out:
512 spin_unlock_irq(&lo->lo_lock);
513 bio_io_error(old_bio);
514}
515
516struct switch_request {
517 struct file *file;
518 struct completion wait;
519};
520
521static void do_loop_switch(struct loop_device *, struct switch_request *);
522
523static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio)
524{
525 if (unlikely(!bio->bi_bdev)) {
526 do_loop_switch(lo, bio->bi_private);
527 bio_put(bio);
528 } else {
529 int ret = do_bio_filebacked(lo, bio);
530 bio_endio(bio, ret);
531 }
532}
533
534/*
535 * worker thread that handles reads/writes to file backed loop devices,
536 * to avoid blocking in our make_request_fn. it also does loop decrypting
537 * on reads for block backed loop, as that is too heavy to do from
538 * b_end_io context where irqs may be disabled.
539 *
540 * Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before
541 * calling kthread_stop(). Therefore once kthread_should_stop() is
542 * true, make_request will not place any more requests. Therefore
543 * once kthread_should_stop() is true and lo_bio is NULL, we are
544 * done with the loop.
545 */
546static int loop_thread(void *data)
547{
548 struct loop_device *lo = data;
549 struct bio *bio;
550
551 set_user_nice(current, -20);
552
553 while (!kthread_should_stop() || !bio_list_empty(&lo->lo_bio_list)) {
554
555 wait_event_interruptible(lo->lo_event,
556 !bio_list_empty(&lo->lo_bio_list) ||
557 kthread_should_stop());
558
559 if (bio_list_empty(&lo->lo_bio_list))
560 continue;
561 spin_lock_irq(&lo->lo_lock);
562 bio = loop_get_bio(lo);
563 if (lo->lo_bio_count < lo->lo_queue->nr_congestion_off)
564 wake_up(&lo->lo_req_wait);
565 spin_unlock_irq(&lo->lo_lock);
566
567 BUG_ON(!bio);
568 loop_handle_bio(lo, bio);
569 }
570
571 return 0;
572}
573
574/*
575 * loop_switch performs the hard work of switching a backing store.
576 * First it needs to flush existing IO, it does this by sending a magic
577 * BIO down the pipe. The completion of this BIO does the actual switch.
578 */
579static int loop_switch(struct loop_device *lo, struct file *file)
580{
581 struct switch_request w;
582 struct bio *bio = bio_alloc(GFP_KERNEL, 0);
583 if (!bio)
584 return -ENOMEM;
585 init_completion(&w.wait);
586 w.file = file;
587 bio->bi_private = &w;
588 bio->bi_bdev = NULL;
589 loop_make_request(lo->lo_queue, bio);
590 wait_for_completion(&w.wait);
591 return 0;
592}
593
594/*
595 * Helper to flush the IOs in loop, but keeping loop thread running
596 */
597static int loop_flush(struct loop_device *lo)
598{
599 /* loop not yet configured, no running thread, nothing to flush */
600 if (!lo->lo_thread)
601 return 0;
602
603 return loop_switch(lo, NULL);
604}
605
606/*
607 * Do the actual switch; called from the BIO completion routine
608 */
609static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
610{
611 struct file *file = p->file;
612 struct file *old_file = lo->lo_backing_file;
613 struct address_space *mapping;
614
615 /* if no new file, only flush of queued bios requested */
616 if (!file)
617 goto out;
618
619 mapping = file->f_mapping;
620 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
621 lo->lo_backing_file = file;
622 lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
623 mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
624 lo->old_gfp_mask = mapping_gfp_mask(mapping);
625 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
626out:
627 complete(&p->wait);
628}
629
630
631/*
632 * loop_change_fd switched the backing store of a loopback device to
633 * a new file. This is useful for operating system installers to free up
634 * the original file and in High Availability environments to switch to
635 * an alternative location for the content in case of server meltdown.
636 * This can only work if the loop device is used read-only, and if the
637 * new backing store is the same size and type as the old backing store.
638 */
639static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
640 unsigned int arg)
641{
642 struct file *file, *old_file;
643 struct inode *inode;
644 int error;
645
646 error = -ENXIO;
647 if (lo->lo_state != Lo_bound)
648 goto out;
649
650 /* the loop device has to be read-only */
651 error = -EINVAL;
652 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
653 goto out;
654
655 error = -EBADF;
656 file = fget(arg);
657 if (!file)
658 goto out;
659
660 inode = file->f_mapping->host;
661 old_file = lo->lo_backing_file;
662
663 error = -EINVAL;
664
665 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
666 goto out_putf;
667
668 /* size of the new backing store needs to be the same */
669 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
670 goto out_putf;
671
672 /* and ... switch */
673 error = loop_switch(lo, file);
674 if (error)
675 goto out_putf;
676
677 fput(old_file);
678 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
679 ioctl_by_bdev(bdev, BLKRRPART, 0);
680 return 0;
681
682 out_putf:
683 fput(file);
684 out:
685 return error;
686}
687
688static inline int is_loop_device(struct file *file)
689{
690 struct inode *i = file->f_mapping->host;
691
692 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
693}
694
695/* loop sysfs attributes */
696
697static ssize_t loop_attr_show(struct device *dev, char *page,
698 ssize_t (*callback)(struct loop_device *, char *))
699{
700 struct gendisk *disk = dev_to_disk(dev);
701 struct loop_device *lo = disk->private_data;
702
703 return callback(lo, page);
704}
705
706#define LOOP_ATTR_RO(_name) \
707static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
708static ssize_t loop_attr_do_show_##_name(struct device *d, \
709 struct device_attribute *attr, char *b) \
710{ \
711 return loop_attr_show(d, b, loop_attr_##_name##_show); \
712} \
713static struct device_attribute loop_attr_##_name = \
714 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
715
716static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
717{
718 ssize_t ret;
719 char *p = NULL;
720
721 spin_lock_irq(&lo->lo_lock);
722 if (lo->lo_backing_file)
723 p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1);
724 spin_unlock_irq(&lo->lo_lock);
725
726 if (IS_ERR_OR_NULL(p))
727 ret = PTR_ERR(p);
728 else {
729 ret = strlen(p);
730 memmove(buf, p, ret);
731 buf[ret++] = '\n';
732 buf[ret] = 0;
733 }
734
735 return ret;
736}
737
738static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
739{
740 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
741}
742
743static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
744{
745 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
746}
747
748static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
749{
750 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
751
752 return sprintf(buf, "%s\n", autoclear ? "1" : "0");
753}
754
755static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
756{
757 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
758
759 return sprintf(buf, "%s\n", partscan ? "1" : "0");
760}
761
762LOOP_ATTR_RO(backing_file);
763LOOP_ATTR_RO(offset);
764LOOP_ATTR_RO(sizelimit);
765LOOP_ATTR_RO(autoclear);
766LOOP_ATTR_RO(partscan);
767
768static struct attribute *loop_attrs[] = {
769 &loop_attr_backing_file.attr,
770 &loop_attr_offset.attr,
771 &loop_attr_sizelimit.attr,
772 &loop_attr_autoclear.attr,
773 &loop_attr_partscan.attr,
774 NULL,
775};
776
777static struct attribute_group loop_attribute_group = {
778 .name = "loop",
779 .attrs= loop_attrs,
780};
781
782static int loop_sysfs_init(struct loop_device *lo)
783{
784 return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
785 &loop_attribute_group);
786}
787
788static void loop_sysfs_exit(struct loop_device *lo)
789{
790 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
791 &loop_attribute_group);
792}
793
794static void loop_config_discard(struct loop_device *lo)
795{
796 struct file *file = lo->lo_backing_file;
797 struct inode *inode = file->f_mapping->host;
798 struct request_queue *q = lo->lo_queue;
799
800 /*
801 * We use punch hole to reclaim the free space used by the
802 * image a.k.a. discard. However we do not support discard if
803 * encryption is enabled, because it may give an attacker
804 * useful information.
805 */
806 if ((!file->f_op->fallocate) ||
807 lo->lo_encrypt_key_size) {
808 q->limits.discard_granularity = 0;
809 q->limits.discard_alignment = 0;
810 q->limits.max_discard_sectors = 0;
811 q->limits.discard_zeroes_data = 0;
812 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
813 return;
814 }
815
816 q->limits.discard_granularity = inode->i_sb->s_blocksize;
817 q->limits.discard_alignment = 0;
818 q->limits.max_discard_sectors = UINT_MAX >> 9;
819 q->limits.discard_zeroes_data = 1;
820 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
821}
822
823static int loop_set_fd(struct loop_device *lo, fmode_t mode,
824 struct block_device *bdev, unsigned int arg)
825{
826 struct file *file, *f;
827 struct inode *inode;
828 struct address_space *mapping;
829 unsigned lo_blocksize;
830 int lo_flags = 0;
831 int error;
832 loff_t size;
833
834 /* This is safe, since we have a reference from open(). */
835 __module_get(THIS_MODULE);
836
837 error = -EBADF;
838 file = fget(arg);
839 if (!file)
840 goto out;
841
842 error = -EBUSY;
843 if (lo->lo_state != Lo_unbound)
844 goto out_putf;
845
846 /* Avoid recursion */
847 f = file;
848 while (is_loop_device(f)) {
849 struct loop_device *l;
850
851 if (f->f_mapping->host->i_bdev == bdev)
852 goto out_putf;
853
854 l = f->f_mapping->host->i_bdev->bd_disk->private_data;
855 if (l->lo_state == Lo_unbound) {
856 error = -EINVAL;
857 goto out_putf;
858 }
859 f = l->lo_backing_file;
860 }
861
862 mapping = file->f_mapping;
863 inode = mapping->host;
864
865 error = -EINVAL;
866 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
867 goto out_putf;
868
869 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
870 !file->f_op->write)
871 lo_flags |= LO_FLAGS_READ_ONLY;
872
873 lo_blocksize = S_ISBLK(inode->i_mode) ?
874 inode->i_bdev->bd_block_size : PAGE_SIZE;
875
876 error = -EFBIG;
877 size = get_loop_size(lo, file);
878 if ((loff_t)(sector_t)size != size)
879 goto out_putf;
880
881 error = 0;
882
883 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
884
885 lo->lo_blocksize = lo_blocksize;
886 lo->lo_device = bdev;
887 lo->lo_flags = lo_flags;
888 lo->lo_backing_file = file;
889 lo->transfer = transfer_none;
890 lo->ioctl = NULL;
891 lo->lo_sizelimit = 0;
892 lo->lo_bio_count = 0;
893 lo->old_gfp_mask = mapping_gfp_mask(mapping);
894 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
895
896 bio_list_init(&lo->lo_bio_list);
897
898 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
899 blk_queue_flush(lo->lo_queue, REQ_FLUSH);
900
901 set_capacity(lo->lo_disk, size);
902 bd_set_size(bdev, size << 9);
903 loop_sysfs_init(lo);
904 /* let user-space know about the new size */
905 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
906
907 set_blocksize(bdev, lo_blocksize);
908
909 lo->lo_thread = kthread_create(loop_thread, lo, "loop%d",
910 lo->lo_number);
911 if (IS_ERR(lo->lo_thread)) {
912 error = PTR_ERR(lo->lo_thread);
913 goto out_clr;
914 }
915 lo->lo_state = Lo_bound;
916 wake_up_process(lo->lo_thread);
917 if (part_shift)
918 lo->lo_flags |= LO_FLAGS_PARTSCAN;
919 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
920 ioctl_by_bdev(bdev, BLKRRPART, 0);
921
922 /* Grab the block_device to prevent its destruction after we
923 * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev).
924 */
925 bdgrab(bdev);
926 return 0;
927
928out_clr:
929 loop_sysfs_exit(lo);
930 lo->lo_thread = NULL;
931 lo->lo_device = NULL;
932 lo->lo_backing_file = NULL;
933 lo->lo_flags = 0;
934 set_capacity(lo->lo_disk, 0);
935 invalidate_bdev(bdev);
936 bd_set_size(bdev, 0);
937 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
938 mapping_set_gfp_mask(mapping, lo->old_gfp_mask);
939 lo->lo_state = Lo_unbound;
940 out_putf:
941 fput(file);
942 out:
943 /* This is safe: open() is still holding a reference. */
944 module_put(THIS_MODULE);
945 return error;
946}
947
948static int
949loop_release_xfer(struct loop_device *lo)
950{
951 int err = 0;
952 struct loop_func_table *xfer = lo->lo_encryption;
953
954 if (xfer) {
955 if (xfer->release)
956 err = xfer->release(lo);
957 lo->transfer = NULL;
958 lo->lo_encryption = NULL;
959 module_put(xfer->owner);
960 }
961 return err;
962}
963
964static int
965loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
966 const struct loop_info64 *i)
967{
968 int err = 0;
969
970 if (xfer) {
971 struct module *owner = xfer->owner;
972
973 if (!try_module_get(owner))
974 return -EINVAL;
975 if (xfer->init)
976 err = xfer->init(lo, i);
977 if (err)
978 module_put(owner);
979 else
980 lo->lo_encryption = xfer;
981 }
982 return err;
983}
984
985static int loop_clr_fd(struct loop_device *lo)
986{
987 struct file *filp = lo->lo_backing_file;
988 gfp_t gfp = lo->old_gfp_mask;
989 struct block_device *bdev = lo->lo_device;
990
991 if (lo->lo_state != Lo_bound)
992 return -ENXIO;
993
994 /*
995 * If we've explicitly asked to tear down the loop device,
996 * and it has an elevated reference count, set it for auto-teardown when
997 * the last reference goes away. This stops $!~#$@ udev from
998 * preventing teardown because it decided that it needs to run blkid on
999 * the loopback device whenever they appear. xfstests is notorious for
1000 * failing tests because blkid via udev races with a losetup
1001 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
1002 * command to fail with EBUSY.
1003 */
1004 if (lo->lo_refcnt > 1) {
1005 lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
1006 mutex_unlock(&lo->lo_ctl_mutex);
1007 return 0;
1008 }
1009
1010 if (filp == NULL)
1011 return -EINVAL;
1012
1013 spin_lock_irq(&lo->lo_lock);
1014 lo->lo_state = Lo_rundown;
1015 spin_unlock_irq(&lo->lo_lock);
1016
1017 kthread_stop(lo->lo_thread);
1018
1019 spin_lock_irq(&lo->lo_lock);
1020 lo->lo_backing_file = NULL;
1021 spin_unlock_irq(&lo->lo_lock);
1022
1023 loop_release_xfer(lo);
1024 lo->transfer = NULL;
1025 lo->ioctl = NULL;
1026 lo->lo_device = NULL;
1027 lo->lo_encryption = NULL;
1028 lo->lo_offset = 0;
1029 lo->lo_sizelimit = 0;
1030 lo->lo_encrypt_key_size = 0;
1031 lo->lo_thread = NULL;
1032 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
1033 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
1034 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1035 if (bdev) {
1036 bdput(bdev);
1037 invalidate_bdev(bdev);
1038 }
1039 set_capacity(lo->lo_disk, 0);
1040 loop_sysfs_exit(lo);
1041 if (bdev) {
1042 bd_set_size(bdev, 0);
1043 /* let user-space know about this change */
1044 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1045 }
1046 mapping_set_gfp_mask(filp->f_mapping, gfp);
1047 lo->lo_state = Lo_unbound;
1048 /* This is safe: open() is still holding a reference. */
1049 module_put(THIS_MODULE);
1050 if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
1051 ioctl_by_bdev(bdev, BLKRRPART, 0);
1052 lo->lo_flags = 0;
1053 if (!part_shift)
1054 lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
1055 mutex_unlock(&lo->lo_ctl_mutex);
1056 /*
1057 * Need not hold lo_ctl_mutex to fput backing file.
1058 * Calling fput holding lo_ctl_mutex triggers a circular
1059 * lock dependency possibility warning as fput can take
1060 * bd_mutex which is usually taken before lo_ctl_mutex.
1061 */
1062 fput(filp);
1063 return 0;
1064}
1065
1066static int
1067loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1068{
1069 int err;
1070 struct loop_func_table *xfer;
1071 kuid_t uid = current_uid();
1072
1073 if (lo->lo_encrypt_key_size &&
1074 !uid_eq(lo->lo_key_owner, uid) &&
1075 !capable(CAP_SYS_ADMIN))
1076 return -EPERM;
1077 if (lo->lo_state != Lo_bound)
1078 return -ENXIO;
1079 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
1080 return -EINVAL;
1081
1082 err = loop_release_xfer(lo);
1083 if (err)
1084 return err;
1085
1086 if (info->lo_encrypt_type) {
1087 unsigned int type = info->lo_encrypt_type;
1088
1089 if (type >= MAX_LO_CRYPT)
1090 return -EINVAL;
1091 xfer = xfer_funcs[type];
1092 if (xfer == NULL)
1093 return -EINVAL;
1094 } else
1095 xfer = NULL;
1096
1097 err = loop_init_xfer(lo, xfer, info);
1098 if (err)
1099 return err;
1100
1101 if (lo->lo_offset != info->lo_offset ||
1102 lo->lo_sizelimit != info->lo_sizelimit)
1103 if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
1104 return -EFBIG;
1105
1106 loop_config_discard(lo);
1107
1108 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
1109 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
1110 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
1111 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
1112
1113 if (!xfer)
1114 xfer = &none_funcs;
1115 lo->transfer = xfer->transfer;
1116 lo->ioctl = xfer->ioctl;
1117
1118 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
1119 (info->lo_flags & LO_FLAGS_AUTOCLEAR))
1120 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
1121
1122 if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&
1123 !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
1124 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1125 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
1126 ioctl_by_bdev(lo->lo_device, BLKRRPART, 0);
1127 }
1128
1129 lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
1130 lo->lo_init[0] = info->lo_init[0];
1131 lo->lo_init[1] = info->lo_init[1];
1132 if (info->lo_encrypt_key_size) {
1133 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
1134 info->lo_encrypt_key_size);
1135 lo->lo_key_owner = uid;
1136 }
1137
1138 return 0;
1139}
1140
1141static int
1142loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1143{
1144 struct file *file = lo->lo_backing_file;
1145 struct kstat stat;
1146 int error;
1147
1148 if (lo->lo_state != Lo_bound)
1149 return -ENXIO;
1150 error = vfs_getattr(&file->f_path, &stat);
1151 if (error)
1152 return error;
1153 memset(info, 0, sizeof(*info));
1154 info->lo_number = lo->lo_number;
1155 info->lo_device = huge_encode_dev(stat.dev);
1156 info->lo_inode = stat.ino;
1157 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
1158 info->lo_offset = lo->lo_offset;
1159 info->lo_sizelimit = lo->lo_sizelimit;
1160 info->lo_flags = lo->lo_flags;
1161 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1162 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1163 info->lo_encrypt_type =
1164 lo->lo_encryption ? lo->lo_encryption->number : 0;
1165 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1166 info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1167 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1168 lo->lo_encrypt_key_size);
1169 }
1170 return 0;
1171}
1172
1173static void
1174loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1175{
1176 memset(info64, 0, sizeof(*info64));
1177 info64->lo_number = info->lo_number;
1178 info64->lo_device = info->lo_device;
1179 info64->lo_inode = info->lo_inode;
1180 info64->lo_rdevice = info->lo_rdevice;
1181 info64->lo_offset = info->lo_offset;
1182 info64->lo_sizelimit = 0;
1183 info64->lo_encrypt_type = info->lo_encrypt_type;
1184 info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1185 info64->lo_flags = info->lo_flags;
1186 info64->lo_init[0] = info->lo_init[0];
1187 info64->lo_init[1] = info->lo_init[1];
1188 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1189 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1190 else
1191 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1192 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1193}
1194
1195static int
1196loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1197{
1198 memset(info, 0, sizeof(*info));
1199 info->lo_number = info64->lo_number;
1200 info->lo_device = info64->lo_device;
1201 info->lo_inode = info64->lo_inode;
1202 info->lo_rdevice = info64->lo_rdevice;
1203 info->lo_offset = info64->lo_offset;
1204 info->lo_encrypt_type = info64->lo_encrypt_type;
1205 info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1206 info->lo_flags = info64->lo_flags;
1207 info->lo_init[0] = info64->lo_init[0];
1208 info->lo_init[1] = info64->lo_init[1];
1209 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1210 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1211 else
1212 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1213 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1214
1215 /* error in case values were truncated */
1216 if (info->lo_device != info64->lo_device ||
1217 info->lo_rdevice != info64->lo_rdevice ||
1218 info->lo_inode != info64->lo_inode ||
1219 info->lo_offset != info64->lo_offset)
1220 return -EOVERFLOW;
1221
1222 return 0;
1223}
1224
1225static int
1226loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1227{
1228 struct loop_info info;
1229 struct loop_info64 info64;
1230
1231 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1232 return -EFAULT;
1233 loop_info64_from_old(&info, &info64);
1234 return loop_set_status(lo, &info64);
1235}
1236
1237static int
1238loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1239{
1240 struct loop_info64 info64;
1241
1242 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1243 return -EFAULT;
1244 return loop_set_status(lo, &info64);
1245}
1246
1247static int
1248loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1249 struct loop_info info;
1250 struct loop_info64 info64;
1251 int err = 0;
1252
1253 if (!arg)
1254 err = -EINVAL;
1255 if (!err)
1256 err = loop_get_status(lo, &info64);
1257 if (!err)
1258 err = loop_info64_to_old(&info64, &info);
1259 if (!err && copy_to_user(arg, &info, sizeof(info)))
1260 err = -EFAULT;
1261
1262 return err;
1263}
1264
1265static int
1266loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1267 struct loop_info64 info64;
1268 int err = 0;
1269
1270 if (!arg)
1271 err = -EINVAL;
1272 if (!err)
1273 err = loop_get_status(lo, &info64);
1274 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1275 err = -EFAULT;
1276
1277 return err;
1278}
1279
1280static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
1281{
1282 if (unlikely(lo->lo_state != Lo_bound))
1283 return -ENXIO;
1284
1285 return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
1286}
1287
1288static int lo_ioctl(struct block_device *bdev, fmode_t mode,
1289 unsigned int cmd, unsigned long arg)
1290{
1291 struct loop_device *lo = bdev->bd_disk->private_data;
1292 int err;
1293
1294 mutex_lock_nested(&lo->lo_ctl_mutex, 1);
1295 switch (cmd) {
1296 case LOOP_SET_FD:
1297 err = loop_set_fd(lo, mode, bdev, arg);
1298 break;
1299 case LOOP_CHANGE_FD:
1300 err = loop_change_fd(lo, bdev, arg);
1301 break;
1302 case LOOP_CLR_FD:
1303 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1304 err = loop_clr_fd(lo);
1305 if (!err)
1306 goto out_unlocked;
1307 break;
1308 case LOOP_SET_STATUS:
1309 err = -EPERM;
1310 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1311 err = loop_set_status_old(lo,
1312 (struct loop_info __user *)arg);
1313 break;
1314 case LOOP_GET_STATUS:
1315 err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1316 break;
1317 case LOOP_SET_STATUS64:
1318 err = -EPERM;
1319 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1320 err = loop_set_status64(lo,
1321 (struct loop_info64 __user *) arg);
1322 break;
1323 case LOOP_GET_STATUS64:
1324 err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1325 break;
1326 case LOOP_SET_CAPACITY:
1327 err = -EPERM;
1328 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1329 err = loop_set_capacity(lo, bdev);
1330 break;
1331 default:
1332 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1333 }
1334 mutex_unlock(&lo->lo_ctl_mutex);
1335
1336out_unlocked:
1337 return err;
1338}
1339
1340#ifdef CONFIG_COMPAT
1341struct compat_loop_info {
1342 compat_int_t lo_number; /* ioctl r/o */
1343 compat_dev_t lo_device; /* ioctl r/o */
1344 compat_ulong_t lo_inode; /* ioctl r/o */
1345 compat_dev_t lo_rdevice; /* ioctl r/o */
1346 compat_int_t lo_offset;
1347 compat_int_t lo_encrypt_type;
1348 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1349 compat_int_t lo_flags; /* ioctl r/o */
1350 char lo_name[LO_NAME_SIZE];
1351 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1352 compat_ulong_t lo_init[2];
1353 char reserved[4];
1354};
1355
1356/*
1357 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1358 * - noinlined to reduce stack space usage in main part of driver
1359 */
1360static noinline int
1361loop_info64_from_compat(const struct compat_loop_info __user *arg,
1362 struct loop_info64 *info64)
1363{
1364 struct compat_loop_info info;
1365
1366 if (copy_from_user(&info, arg, sizeof(info)))
1367 return -EFAULT;
1368
1369 memset(info64, 0, sizeof(*info64));
1370 info64->lo_number = info.lo_number;
1371 info64->lo_device = info.lo_device;
1372 info64->lo_inode = info.lo_inode;
1373 info64->lo_rdevice = info.lo_rdevice;
1374 info64->lo_offset = info.lo_offset;
1375 info64->lo_sizelimit = 0;
1376 info64->lo_encrypt_type = info.lo_encrypt_type;
1377 info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1378 info64->lo_flags = info.lo_flags;
1379 info64->lo_init[0] = info.lo_init[0];
1380 info64->lo_init[1] = info.lo_init[1];
1381 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1382 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1383 else
1384 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1385 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1386 return 0;
1387}
1388
1389/*
1390 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1391 * - noinlined to reduce stack space usage in main part of driver
1392 */
1393static noinline int
1394loop_info64_to_compat(const struct loop_info64 *info64,
1395 struct compat_loop_info __user *arg)
1396{
1397 struct compat_loop_info info;
1398
1399 memset(&info, 0, sizeof(info));
1400 info.lo_number = info64->lo_number;
1401 info.lo_device = info64->lo_device;
1402 info.lo_inode = info64->lo_inode;
1403 info.lo_rdevice = info64->lo_rdevice;
1404 info.lo_offset = info64->lo_offset;
1405 info.lo_encrypt_type = info64->lo_encrypt_type;
1406 info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
1407 info.lo_flags = info64->lo_flags;
1408 info.lo_init[0] = info64->lo_init[0];
1409 info.lo_init[1] = info64->lo_init[1];
1410 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1411 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1412 else
1413 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1414 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1415
1416 /* error in case values were truncated */
1417 if (info.lo_device != info64->lo_device ||
1418 info.lo_rdevice != info64->lo_rdevice ||
1419 info.lo_inode != info64->lo_inode ||
1420 info.lo_offset != info64->lo_offset ||
1421 info.lo_init[0] != info64->lo_init[0] ||
1422 info.lo_init[1] != info64->lo_init[1])
1423 return -EOVERFLOW;
1424
1425 if (copy_to_user(arg, &info, sizeof(info)))
1426 return -EFAULT;
1427 return 0;
1428}
1429
1430static int
1431loop_set_status_compat(struct loop_device *lo,
1432 const struct compat_loop_info __user *arg)
1433{
1434 struct loop_info64 info64;
1435 int ret;
1436
1437 ret = loop_info64_from_compat(arg, &info64);
1438 if (ret < 0)
1439 return ret;
1440 return loop_set_status(lo, &info64);
1441}
1442
1443static int
1444loop_get_status_compat(struct loop_device *lo,
1445 struct compat_loop_info __user *arg)
1446{
1447 struct loop_info64 info64;
1448 int err = 0;
1449
1450 if (!arg)
1451 err = -EINVAL;
1452 if (!err)
1453 err = loop_get_status(lo, &info64);
1454 if (!err)
1455 err = loop_info64_to_compat(&info64, arg);
1456 return err;
1457}
1458
1459static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1460 unsigned int cmd, unsigned long arg)
1461{
1462 struct loop_device *lo = bdev->bd_disk->private_data;
1463 int err;
1464
1465 switch(cmd) {
1466 case LOOP_SET_STATUS:
1467 mutex_lock(&lo->lo_ctl_mutex);
1468 err = loop_set_status_compat(
1469 lo, (const struct compat_loop_info __user *) arg);
1470 mutex_unlock(&lo->lo_ctl_mutex);
1471 break;
1472 case LOOP_GET_STATUS:
1473 mutex_lock(&lo->lo_ctl_mutex);
1474 err = loop_get_status_compat(
1475 lo, (struct compat_loop_info __user *) arg);
1476 mutex_unlock(&lo->lo_ctl_mutex);
1477 break;
1478 case LOOP_SET_CAPACITY:
1479 case LOOP_CLR_FD:
1480 case LOOP_GET_STATUS64:
1481 case LOOP_SET_STATUS64:
1482 arg = (unsigned long) compat_ptr(arg);
1483 case LOOP_SET_FD:
1484 case LOOP_CHANGE_FD:
1485 err = lo_ioctl(bdev, mode, cmd, arg);
1486 break;
1487 default:
1488 err = -ENOIOCTLCMD;
1489 break;
1490 }
1491 return err;
1492}
1493#endif
1494
1495static int lo_open(struct block_device *bdev, fmode_t mode)
1496{
1497 struct loop_device *lo;
1498 int err = 0;
1499
1500 mutex_lock(&loop_index_mutex);
1501 lo = bdev->bd_disk->private_data;
1502 if (!lo) {
1503 err = -ENXIO;
1504 goto out;
1505 }
1506
1507 mutex_lock(&lo->lo_ctl_mutex);
1508 lo->lo_refcnt++;
1509 mutex_unlock(&lo->lo_ctl_mutex);
1510out:
1511 mutex_unlock(&loop_index_mutex);
1512 return err;
1513}
1514
1515static void lo_release(struct gendisk *disk, fmode_t mode)
1516{
1517 struct loop_device *lo = disk->private_data;
1518 int err;
1519
1520 mutex_lock(&lo->lo_ctl_mutex);
1521
1522 if (--lo->lo_refcnt)
1523 goto out;
1524
1525 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
1526 /*
1527 * In autoclear mode, stop the loop thread
1528 * and remove configuration after last close.
1529 */
1530 err = loop_clr_fd(lo);
1531 if (!err)
1532 return;
1533 } else {
1534 /*
1535 * Otherwise keep thread (if running) and config,
1536 * but flush possible ongoing bios in thread.
1537 */
1538 loop_flush(lo);
1539 }
1540
1541out:
1542 mutex_unlock(&lo->lo_ctl_mutex);
1543}
1544
1545static const struct block_device_operations lo_fops = {
1546 .owner = THIS_MODULE,
1547 .open = lo_open,
1548 .release = lo_release,
1549 .ioctl = lo_ioctl,
1550#ifdef CONFIG_COMPAT
1551 .compat_ioctl = lo_compat_ioctl,
1552#endif
1553};
1554
1555/*
1556 * And now the modules code and kernel interface.
1557 */
1558static int max_loop;
1559module_param(max_loop, int, S_IRUGO);
1560MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1561module_param(max_part, int, S_IRUGO);
1562MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1563MODULE_LICENSE("GPL");
1564MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1565
1566int loop_register_transfer(struct loop_func_table *funcs)
1567{
1568 unsigned int n = funcs->number;
1569
1570 if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1571 return -EINVAL;
1572 xfer_funcs[n] = funcs;
1573 return 0;
1574}
1575
1576static int unregister_transfer_cb(int id, void *ptr, void *data)
1577{
1578 struct loop_device *lo = ptr;
1579 struct loop_func_table *xfer = data;
1580
1581 mutex_lock(&lo->lo_ctl_mutex);
1582 if (lo->lo_encryption == xfer)
1583 loop_release_xfer(lo);
1584 mutex_unlock(&lo->lo_ctl_mutex);
1585 return 0;
1586}
1587
1588int loop_unregister_transfer(int number)
1589{
1590 unsigned int n = number;
1591 struct loop_func_table *xfer;
1592
1593 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1594 return -EINVAL;
1595
1596 xfer_funcs[n] = NULL;
1597 idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
1598 return 0;
1599}
1600
1601EXPORT_SYMBOL(loop_register_transfer);
1602EXPORT_SYMBOL(loop_unregister_transfer);
1603
1604static int loop_add(struct loop_device **l, int i)
1605{
1606 struct loop_device *lo;
1607 struct gendisk *disk;
1608 int err;
1609
1610 err = -ENOMEM;
1611 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1612 if (!lo)
1613 goto out;
1614
1615 lo->lo_state = Lo_unbound;
1616
1617 /* allocate id, if @id >= 0, we're requesting that specific id */
1618 if (i >= 0) {
1619 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
1620 if (err == -ENOSPC)
1621 err = -EEXIST;
1622 } else {
1623 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
1624 }
1625 if (err < 0)
1626 goto out_free_dev;
1627 i = err;
1628
1629 err = -ENOMEM;
1630 lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
1631 if (!lo->lo_queue)
1632 goto out_free_idr;
1633
1634 /*
1635 * set queue make_request_fn
1636 */
1637 blk_queue_make_request(lo->lo_queue, loop_make_request);
1638 lo->lo_queue->queuedata = lo;
1639
1640 disk = lo->lo_disk = alloc_disk(1 << part_shift);
1641 if (!disk)
1642 goto out_free_queue;
1643
1644 /*
1645 * Disable partition scanning by default. The in-kernel partition
1646 * scanning can be requested individually per-device during its
1647 * setup. Userspace can always add and remove partitions from all
1648 * devices. The needed partition minors are allocated from the
1649 * extended minor space, the main loop device numbers will continue
1650 * to match the loop minors, regardless of the number of partitions
1651 * used.
1652 *
1653 * If max_part is given, partition scanning is globally enabled for
1654 * all loop devices. The minors for the main loop devices will be
1655 * multiples of max_part.
1656 *
1657 * Note: Global-for-all-devices, set-only-at-init, read-only module
1658 * parameteters like 'max_loop' and 'max_part' make things needlessly
1659 * complicated, are too static, inflexible and may surprise
1660 * userspace tools. Parameters like this in general should be avoided.
1661 */
1662 if (!part_shift)
1663 disk->flags |= GENHD_FL_NO_PART_SCAN;
1664 disk->flags |= GENHD_FL_EXT_DEVT;
1665 mutex_init(&lo->lo_ctl_mutex);
1666 lo->lo_number = i;
1667 lo->lo_thread = NULL;
1668 init_waitqueue_head(&lo->lo_event);
1669 init_waitqueue_head(&lo->lo_req_wait);
1670 spin_lock_init(&lo->lo_lock);
1671 disk->major = LOOP_MAJOR;
1672 disk->first_minor = i << part_shift;
1673 disk->fops = &lo_fops;
1674 disk->private_data = lo;
1675 disk->queue = lo->lo_queue;
1676 sprintf(disk->disk_name, "loop%d", i);
1677 add_disk(disk);
1678 *l = lo;
1679 return lo->lo_number;
1680
1681out_free_queue:
1682 blk_cleanup_queue(lo->lo_queue);
1683out_free_idr:
1684 idr_remove(&loop_index_idr, i);
1685out_free_dev:
1686 kfree(lo);
1687out:
1688 return err;
1689}
1690
1691static void loop_remove(struct loop_device *lo)
1692{
1693 del_gendisk(lo->lo_disk);
1694 blk_cleanup_queue(lo->lo_queue);
1695 put_disk(lo->lo_disk);
1696 kfree(lo);
1697}
1698
1699static int find_free_cb(int id, void *ptr, void *data)
1700{
1701 struct loop_device *lo = ptr;
1702 struct loop_device **l = data;
1703
1704 if (lo->lo_state == Lo_unbound) {
1705 *l = lo;
1706 return 1;
1707 }
1708 return 0;
1709}
1710
1711static int loop_lookup(struct loop_device **l, int i)
1712{
1713 struct loop_device *lo;
1714 int ret = -ENODEV;
1715
1716 if (i < 0) {
1717 int err;
1718
1719 err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
1720 if (err == 1) {
1721 *l = lo;
1722 ret = lo->lo_number;
1723 }
1724 goto out;
1725 }
1726
1727 /* lookup and return a specific i */
1728 lo = idr_find(&loop_index_idr, i);
1729 if (lo) {
1730 *l = lo;
1731 ret = lo->lo_number;
1732 }
1733out:
1734 return ret;
1735}
1736
1737static struct kobject *loop_probe(dev_t dev, int *part, void *data)
1738{
1739 struct loop_device *lo;
1740 struct kobject *kobj;
1741 int err;
1742
1743 mutex_lock(&loop_index_mutex);
1744 err = loop_lookup(&lo, MINOR(dev) >> part_shift);
1745 if (err < 0)
1746 err = loop_add(&lo, MINOR(dev) >> part_shift);
1747 if (err < 0)
1748 kobj = NULL;
1749 else
1750 kobj = get_disk(lo->lo_disk);
1751 mutex_unlock(&loop_index_mutex);
1752
1753 *part = 0;
1754 return kobj;
1755}
1756
1757static long loop_control_ioctl(struct file *file, unsigned int cmd,
1758 unsigned long parm)
1759{
1760 struct loop_device *lo;
1761 int ret = -ENOSYS;
1762
1763 mutex_lock(&loop_index_mutex);
1764 switch (cmd) {
1765 case LOOP_CTL_ADD:
1766 ret = loop_lookup(&lo, parm);
1767 if (ret >= 0) {
1768 ret = -EEXIST;
1769 break;
1770 }
1771 ret = loop_add(&lo, parm);
1772 break;
1773 case LOOP_CTL_REMOVE:
1774 ret = loop_lookup(&lo, parm);
1775 if (ret < 0)
1776 break;
1777 mutex_lock(&lo->lo_ctl_mutex);
1778 if (lo->lo_state != Lo_unbound) {
1779 ret = -EBUSY;
1780 mutex_unlock(&lo->lo_ctl_mutex);
1781 break;
1782 }
1783 if (lo->lo_refcnt > 0) {
1784 ret = -EBUSY;
1785 mutex_unlock(&lo->lo_ctl_mutex);
1786 break;
1787 }
1788 lo->lo_disk->private_data = NULL;
1789 mutex_unlock(&lo->lo_ctl_mutex);
1790 idr_remove(&loop_index_idr, lo->lo_number);
1791 loop_remove(lo);
1792 break;
1793 case LOOP_CTL_GET_FREE:
1794 ret = loop_lookup(&lo, -1);
1795 if (ret >= 0)
1796 break;
1797 ret = loop_add(&lo, -1);
1798 }
1799 mutex_unlock(&loop_index_mutex);
1800
1801 return ret;
1802}
1803
1804static const struct file_operations loop_ctl_fops = {
1805 .open = nonseekable_open,
1806 .unlocked_ioctl = loop_control_ioctl,
1807 .compat_ioctl = loop_control_ioctl,
1808 .owner = THIS_MODULE,
1809 .llseek = noop_llseek,
1810};
1811
1812static struct miscdevice loop_misc = {
1813 .minor = LOOP_CTRL_MINOR,
1814 .name = "loop-control",
1815 .fops = &loop_ctl_fops,
1816};
1817
1818MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
1819MODULE_ALIAS("devname:loop-control");
1820
1821static int __init loop_init(void)
1822{
1823 int i, nr;
1824 unsigned long range;
1825 struct loop_device *lo;
1826 int err;
1827
1828 err = misc_register(&loop_misc);
1829 if (err < 0)
1830 return err;
1831
1832 part_shift = 0;
1833 if (max_part > 0) {
1834 part_shift = fls(max_part);
1835
1836 /*
1837 * Adjust max_part according to part_shift as it is exported
1838 * to user space so that user can decide correct minor number
1839 * if [s]he want to create more devices.
1840 *
1841 * Note that -1 is required because partition 0 is reserved
1842 * for the whole disk.
1843 */
1844 max_part = (1UL << part_shift) - 1;
1845 }
1846
1847 if ((1UL << part_shift) > DISK_MAX_PARTS) {
1848 err = -EINVAL;
1849 goto misc_out;
1850 }
1851
1852 if (max_loop > 1UL << (MINORBITS - part_shift)) {
1853 err = -EINVAL;
1854 goto misc_out;
1855 }
1856
1857 /*
1858 * If max_loop is specified, create that many devices upfront.
1859 * This also becomes a hard limit. If max_loop is not specified,
1860 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1861 * init time. Loop devices can be requested on-demand with the
1862 * /dev/loop-control interface, or be instantiated by accessing
1863 * a 'dead' device node.
1864 */
1865 if (max_loop) {
1866 nr = max_loop;
1867 range = max_loop << part_shift;
1868 } else {
1869 nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1870 range = 1UL << MINORBITS;
1871 }
1872
1873 if (register_blkdev(LOOP_MAJOR, "loop")) {
1874 err = -EIO;
1875 goto misc_out;
1876 }
1877
1878 blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
1879 THIS_MODULE, loop_probe, NULL, NULL);
1880
1881 /* pre-create number of devices given by config or max_loop */
1882 mutex_lock(&loop_index_mutex);
1883 for (i = 0; i < nr; i++)
1884 loop_add(&lo, i);
1885 mutex_unlock(&loop_index_mutex);
1886
1887 printk(KERN_INFO "loop: module loaded\n");
1888 return 0;
1889
1890misc_out:
1891 misc_deregister(&loop_misc);
1892 return err;
1893}
1894
1895static int loop_exit_cb(int id, void *ptr, void *data)
1896{
1897 struct loop_device *lo = ptr;
1898
1899 loop_remove(lo);
1900 return 0;
1901}
1902
1903static void __exit loop_exit(void)
1904{
1905 unsigned long range;
1906
1907 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
1908
1909 idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
1910 idr_destroy(&loop_index_idr);
1911
1912 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
1913 unregister_blkdev(LOOP_MAJOR, "loop");
1914
1915 misc_deregister(&loop_misc);
1916}
1917
1918module_init(loop_init);
1919module_exit(loop_exit);
1920
1921#ifndef MODULE
1922static int __init max_loop_setup(char *str)
1923{
1924 max_loop = simple_strtol(str, NULL, 0);
1925 return 1;
1926}
1927
1928__setup("max_loop=", max_loop_setup);
1929#endif
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. Bolsø, <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 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/compat.h>
67#include <linux/suspend.h>
68#include <linux/freezer.h>
69#include <linux/mutex.h>
70#include <linux/writeback.h>
71#include <linux/completion.h>
72#include <linux/highmem.h>
73#include <linux/kthread.h>
74#include <linux/splice.h>
75#include <linux/sysfs.h>
76#include <linux/miscdevice.h>
77#include <linux/falloc.h>
78#include <linux/uio.h>
79#include "loop.h"
80
81#include <linux/uaccess.h>
82
83static DEFINE_IDR(loop_index_idr);
84static DEFINE_MUTEX(loop_index_mutex);
85
86static int max_part;
87static int part_shift;
88
89static int transfer_xor(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) + raw_off;
95 char *loop_buf = kmap_atomic(loop_page) + loop_off;
96 char *in, *out, *key;
97 int i, keysize;
98
99 if (cmd == READ) {
100 in = raw_buf;
101 out = loop_buf;
102 } else {
103 in = loop_buf;
104 out = raw_buf;
105 }
106
107 key = lo->lo_encrypt_key;
108 keysize = lo->lo_encrypt_key_size;
109 for (i = 0; i < size; i++)
110 *out++ = *in++ ^ key[(i & 511) % keysize];
111
112 kunmap_atomic(loop_buf);
113 kunmap_atomic(raw_buf);
114 cond_resched();
115 return 0;
116}
117
118static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
119{
120 if (unlikely(info->lo_encrypt_key_size <= 0))
121 return -EINVAL;
122 return 0;
123}
124
125static struct loop_func_table none_funcs = {
126 .number = LO_CRYPT_NONE,
127};
128
129static struct loop_func_table xor_funcs = {
130 .number = LO_CRYPT_XOR,
131 .transfer = transfer_xor,
132 .init = xor_init
133};
134
135/* xfer_funcs[0] is special - its release function is never called */
136static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
137 &none_funcs,
138 &xor_funcs
139};
140
141static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
142{
143 loff_t loopsize;
144
145 /* Compute loopsize in bytes */
146 loopsize = i_size_read(file->f_mapping->host);
147 if (offset > 0)
148 loopsize -= offset;
149 /* offset is beyond i_size, weird but possible */
150 if (loopsize < 0)
151 return 0;
152
153 if (sizelimit > 0 && sizelimit < loopsize)
154 loopsize = sizelimit;
155 /*
156 * Unfortunately, if we want to do I/O on the device,
157 * the number of 512-byte sectors has to fit into a sector_t.
158 */
159 return loopsize >> 9;
160}
161
162static loff_t get_loop_size(struct loop_device *lo, struct file *file)
163{
164 return get_size(lo->lo_offset, lo->lo_sizelimit, file);
165}
166
167static void __loop_update_dio(struct loop_device *lo, bool dio)
168{
169 struct file *file = lo->lo_backing_file;
170 struct address_space *mapping = file->f_mapping;
171 struct inode *inode = mapping->host;
172 unsigned short sb_bsize = 0;
173 unsigned dio_align = 0;
174 bool use_dio;
175
176 if (inode->i_sb->s_bdev) {
177 sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
178 dio_align = sb_bsize - 1;
179 }
180
181 /*
182 * We support direct I/O only if lo_offset is aligned with the
183 * logical I/O size of backing device, and the logical block
184 * size of loop is bigger than the backing device's and the loop
185 * needn't transform transfer.
186 *
187 * TODO: the above condition may be loosed in the future, and
188 * direct I/O may be switched runtime at that time because most
189 * of requests in sane appplications should be PAGE_SIZE algined
190 */
191 if (dio) {
192 if (queue_logical_block_size(lo->lo_queue) >= sb_bsize &&
193 !(lo->lo_offset & dio_align) &&
194 mapping->a_ops->direct_IO &&
195 !lo->transfer)
196 use_dio = true;
197 else
198 use_dio = false;
199 } else {
200 use_dio = false;
201 }
202
203 if (lo->use_dio == use_dio)
204 return;
205
206 /* flush dirty pages before changing direct IO */
207 vfs_fsync(file, 0);
208
209 /*
210 * The flag of LO_FLAGS_DIRECT_IO is handled similarly with
211 * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup
212 * will get updated by ioctl(LOOP_GET_STATUS)
213 */
214 blk_mq_freeze_queue(lo->lo_queue);
215 lo->use_dio = use_dio;
216 if (use_dio)
217 lo->lo_flags |= LO_FLAGS_DIRECT_IO;
218 else
219 lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
220 blk_mq_unfreeze_queue(lo->lo_queue);
221}
222
223static int
224figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
225{
226 loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
227 sector_t x = (sector_t)size;
228 struct block_device *bdev = lo->lo_device;
229
230 if (unlikely((loff_t)x != size))
231 return -EFBIG;
232 if (lo->lo_offset != offset)
233 lo->lo_offset = offset;
234 if (lo->lo_sizelimit != sizelimit)
235 lo->lo_sizelimit = sizelimit;
236 set_capacity(lo->lo_disk, x);
237 bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
238 /* let user-space know about the new size */
239 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
240 return 0;
241}
242
243static inline int
244lo_do_transfer(struct loop_device *lo, int cmd,
245 struct page *rpage, unsigned roffs,
246 struct page *lpage, unsigned loffs,
247 int size, sector_t rblock)
248{
249 int ret;
250
251 ret = lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
252 if (likely(!ret))
253 return 0;
254
255 printk_ratelimited(KERN_ERR
256 "loop: Transfer error at byte offset %llu, length %i.\n",
257 (unsigned long long)rblock << 9, size);
258 return ret;
259}
260
261static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)
262{
263 struct iov_iter i;
264 ssize_t bw;
265
266 iov_iter_bvec(&i, ITER_BVEC, bvec, 1, bvec->bv_len);
267
268 file_start_write(file);
269 bw = vfs_iter_write(file, &i, ppos);
270 file_end_write(file);
271
272 if (likely(bw == bvec->bv_len))
273 return 0;
274
275 printk_ratelimited(KERN_ERR
276 "loop: Write error at byte offset %llu, length %i.\n",
277 (unsigned long long)*ppos, bvec->bv_len);
278 if (bw >= 0)
279 bw = -EIO;
280 return bw;
281}
282
283static int lo_write_simple(struct loop_device *lo, struct request *rq,
284 loff_t pos)
285{
286 struct bio_vec bvec;
287 struct req_iterator iter;
288 int ret = 0;
289
290 rq_for_each_segment(bvec, rq, iter) {
291 ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
292 if (ret < 0)
293 break;
294 cond_resched();
295 }
296
297 return ret;
298}
299
300/*
301 * This is the slow, transforming version that needs to double buffer the
302 * data as it cannot do the transformations in place without having direct
303 * access to the destination pages of the backing file.
304 */
305static int lo_write_transfer(struct loop_device *lo, struct request *rq,
306 loff_t pos)
307{
308 struct bio_vec bvec, b;
309 struct req_iterator iter;
310 struct page *page;
311 int ret = 0;
312
313 page = alloc_page(GFP_NOIO);
314 if (unlikely(!page))
315 return -ENOMEM;
316
317 rq_for_each_segment(bvec, rq, iter) {
318 ret = lo_do_transfer(lo, WRITE, page, 0, bvec.bv_page,
319 bvec.bv_offset, bvec.bv_len, pos >> 9);
320 if (unlikely(ret))
321 break;
322
323 b.bv_page = page;
324 b.bv_offset = 0;
325 b.bv_len = bvec.bv_len;
326 ret = lo_write_bvec(lo->lo_backing_file, &b, &pos);
327 if (ret < 0)
328 break;
329 }
330
331 __free_page(page);
332 return ret;
333}
334
335static int lo_read_simple(struct loop_device *lo, struct request *rq,
336 loff_t pos)
337{
338 struct bio_vec bvec;
339 struct req_iterator iter;
340 struct iov_iter i;
341 ssize_t len;
342
343 rq_for_each_segment(bvec, rq, iter) {
344 iov_iter_bvec(&i, ITER_BVEC, &bvec, 1, bvec.bv_len);
345 len = vfs_iter_read(lo->lo_backing_file, &i, &pos);
346 if (len < 0)
347 return len;
348
349 flush_dcache_page(bvec.bv_page);
350
351 if (len != bvec.bv_len) {
352 struct bio *bio;
353
354 __rq_for_each_bio(bio, rq)
355 zero_fill_bio(bio);
356 break;
357 }
358 cond_resched();
359 }
360
361 return 0;
362}
363
364static int lo_read_transfer(struct loop_device *lo, struct request *rq,
365 loff_t pos)
366{
367 struct bio_vec bvec, b;
368 struct req_iterator iter;
369 struct iov_iter i;
370 struct page *page;
371 ssize_t len;
372 int ret = 0;
373
374 page = alloc_page(GFP_NOIO);
375 if (unlikely(!page))
376 return -ENOMEM;
377
378 rq_for_each_segment(bvec, rq, iter) {
379 loff_t offset = pos;
380
381 b.bv_page = page;
382 b.bv_offset = 0;
383 b.bv_len = bvec.bv_len;
384
385 iov_iter_bvec(&i, ITER_BVEC, &b, 1, b.bv_len);
386 len = vfs_iter_read(lo->lo_backing_file, &i, &pos);
387 if (len < 0) {
388 ret = len;
389 goto out_free_page;
390 }
391
392 ret = lo_do_transfer(lo, READ, page, 0, bvec.bv_page,
393 bvec.bv_offset, len, offset >> 9);
394 if (ret)
395 goto out_free_page;
396
397 flush_dcache_page(bvec.bv_page);
398
399 if (len != bvec.bv_len) {
400 struct bio *bio;
401
402 __rq_for_each_bio(bio, rq)
403 zero_fill_bio(bio);
404 break;
405 }
406 }
407
408 ret = 0;
409out_free_page:
410 __free_page(page);
411 return ret;
412}
413
414static int lo_discard(struct loop_device *lo, struct request *rq, loff_t pos)
415{
416 /*
417 * We use punch hole to reclaim the free space used by the
418 * image a.k.a. discard. However we do not support discard if
419 * encryption is enabled, because it may give an attacker
420 * useful information.
421 */
422 struct file *file = lo->lo_backing_file;
423 int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
424 int ret;
425
426 if ((!file->f_op->fallocate) || lo->lo_encrypt_key_size) {
427 ret = -EOPNOTSUPP;
428 goto out;
429 }
430
431 ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
432 if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
433 ret = -EIO;
434 out:
435 return ret;
436}
437
438static int lo_req_flush(struct loop_device *lo, struct request *rq)
439{
440 struct file *file = lo->lo_backing_file;
441 int ret = vfs_fsync(file, 0);
442 if (unlikely(ret && ret != -EINVAL))
443 ret = -EIO;
444
445 return ret;
446}
447
448static inline void handle_partial_read(struct loop_cmd *cmd, long bytes)
449{
450 if (bytes < 0 || op_is_write(req_op(cmd->rq)))
451 return;
452
453 if (unlikely(bytes < blk_rq_bytes(cmd->rq))) {
454 struct bio *bio = cmd->rq->bio;
455
456 bio_advance(bio, bytes);
457 zero_fill_bio(bio);
458 }
459}
460
461static void lo_rw_aio_complete(struct kiocb *iocb, long ret, long ret2)
462{
463 struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb);
464 struct request *rq = cmd->rq;
465
466 handle_partial_read(cmd, ret);
467
468 if (ret > 0)
469 ret = 0;
470 else if (ret < 0)
471 ret = -EIO;
472
473 blk_mq_complete_request(rq, ret);
474}
475
476static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
477 loff_t pos, bool rw)
478{
479 struct iov_iter iter;
480 struct bio_vec *bvec;
481 struct bio *bio = cmd->rq->bio;
482 struct file *file = lo->lo_backing_file;
483 int ret;
484
485 /* nomerge for loop request queue */
486 WARN_ON(cmd->rq->bio != cmd->rq->biotail);
487
488 bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
489 iov_iter_bvec(&iter, ITER_BVEC | rw, bvec,
490 bio_segments(bio), blk_rq_bytes(cmd->rq));
491 /*
492 * This bio may be started from the middle of the 'bvec'
493 * because of bio splitting, so offset from the bvec must
494 * be passed to iov iterator
495 */
496 iter.iov_offset = bio->bi_iter.bi_bvec_done;
497
498 cmd->iocb.ki_pos = pos;
499 cmd->iocb.ki_filp = file;
500 cmd->iocb.ki_complete = lo_rw_aio_complete;
501 cmd->iocb.ki_flags = IOCB_DIRECT;
502
503 if (rw == WRITE)
504 ret = file->f_op->write_iter(&cmd->iocb, &iter);
505 else
506 ret = file->f_op->read_iter(&cmd->iocb, &iter);
507
508 if (ret != -EIOCBQUEUED)
509 cmd->iocb.ki_complete(&cmd->iocb, ret, 0);
510 return 0;
511}
512
513static int do_req_filebacked(struct loop_device *lo, struct request *rq)
514{
515 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
516 loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
517
518 /*
519 * lo_write_simple and lo_read_simple should have been covered
520 * by io submit style function like lo_rw_aio(), one blocker
521 * is that lo_read_simple() need to call flush_dcache_page after
522 * the page is written from kernel, and it isn't easy to handle
523 * this in io submit style function which submits all segments
524 * of the req at one time. And direct read IO doesn't need to
525 * run flush_dcache_page().
526 */
527 switch (req_op(rq)) {
528 case REQ_OP_FLUSH:
529 return lo_req_flush(lo, rq);
530 case REQ_OP_DISCARD:
531 return lo_discard(lo, rq, pos);
532 case REQ_OP_WRITE:
533 if (lo->transfer)
534 return lo_write_transfer(lo, rq, pos);
535 else if (cmd->use_aio)
536 return lo_rw_aio(lo, cmd, pos, WRITE);
537 else
538 return lo_write_simple(lo, rq, pos);
539 case REQ_OP_READ:
540 if (lo->transfer)
541 return lo_read_transfer(lo, rq, pos);
542 else if (cmd->use_aio)
543 return lo_rw_aio(lo, cmd, pos, READ);
544 else
545 return lo_read_simple(lo, rq, pos);
546 default:
547 WARN_ON_ONCE(1);
548 return -EIO;
549 break;
550 }
551}
552
553struct switch_request {
554 struct file *file;
555 struct completion wait;
556};
557
558static inline void loop_update_dio(struct loop_device *lo)
559{
560 __loop_update_dio(lo, io_is_direct(lo->lo_backing_file) |
561 lo->use_dio);
562}
563
564/*
565 * Do the actual switch; called from the BIO completion routine
566 */
567static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
568{
569 struct file *file = p->file;
570 struct file *old_file = lo->lo_backing_file;
571 struct address_space *mapping;
572
573 /* if no new file, only flush of queued bios requested */
574 if (!file)
575 return;
576
577 mapping = file->f_mapping;
578 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
579 lo->lo_backing_file = file;
580 lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
581 mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
582 lo->old_gfp_mask = mapping_gfp_mask(mapping);
583 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
584 loop_update_dio(lo);
585}
586
587/*
588 * loop_switch performs the hard work of switching a backing store.
589 * First it needs to flush existing IO, it does this by sending a magic
590 * BIO down the pipe. The completion of this BIO does the actual switch.
591 */
592static int loop_switch(struct loop_device *lo, struct file *file)
593{
594 struct switch_request w;
595
596 w.file = file;
597
598 /* freeze queue and wait for completion of scheduled requests */
599 blk_mq_freeze_queue(lo->lo_queue);
600
601 /* do the switch action */
602 do_loop_switch(lo, &w);
603
604 /* unfreeze */
605 blk_mq_unfreeze_queue(lo->lo_queue);
606
607 return 0;
608}
609
610/*
611 * Helper to flush the IOs in loop, but keeping loop thread running
612 */
613static int loop_flush(struct loop_device *lo)
614{
615 return loop_switch(lo, NULL);
616}
617
618static void loop_reread_partitions(struct loop_device *lo,
619 struct block_device *bdev)
620{
621 int rc;
622
623 /*
624 * bd_mutex has been held already in release path, so don't
625 * acquire it if this function is called in such case.
626 *
627 * If the reread partition isn't from release path, lo_refcnt
628 * must be at least one and it can only become zero when the
629 * current holder is released.
630 */
631 if (!atomic_read(&lo->lo_refcnt))
632 rc = __blkdev_reread_part(bdev);
633 else
634 rc = blkdev_reread_part(bdev);
635 if (rc)
636 pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
637 __func__, lo->lo_number, lo->lo_file_name, rc);
638}
639
640/*
641 * loop_change_fd switched the backing store of a loopback device to
642 * a new file. This is useful for operating system installers to free up
643 * the original file and in High Availability environments to switch to
644 * an alternative location for the content in case of server meltdown.
645 * This can only work if the loop device is used read-only, and if the
646 * new backing store is the same size and type as the old backing store.
647 */
648static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
649 unsigned int arg)
650{
651 struct file *file, *old_file;
652 struct inode *inode;
653 int error;
654
655 error = -ENXIO;
656 if (lo->lo_state != Lo_bound)
657 goto out;
658
659 /* the loop device has to be read-only */
660 error = -EINVAL;
661 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
662 goto out;
663
664 error = -EBADF;
665 file = fget(arg);
666 if (!file)
667 goto out;
668
669 inode = file->f_mapping->host;
670 old_file = lo->lo_backing_file;
671
672 error = -EINVAL;
673
674 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
675 goto out_putf;
676
677 /* size of the new backing store needs to be the same */
678 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
679 goto out_putf;
680
681 /* and ... switch */
682 error = loop_switch(lo, file);
683 if (error)
684 goto out_putf;
685
686 fput(old_file);
687 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
688 loop_reread_partitions(lo, bdev);
689 return 0;
690
691 out_putf:
692 fput(file);
693 out:
694 return error;
695}
696
697static inline int is_loop_device(struct file *file)
698{
699 struct inode *i = file->f_mapping->host;
700
701 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
702}
703
704/* loop sysfs attributes */
705
706static ssize_t loop_attr_show(struct device *dev, char *page,
707 ssize_t (*callback)(struct loop_device *, char *))
708{
709 struct gendisk *disk = dev_to_disk(dev);
710 struct loop_device *lo = disk->private_data;
711
712 return callback(lo, page);
713}
714
715#define LOOP_ATTR_RO(_name) \
716static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
717static ssize_t loop_attr_do_show_##_name(struct device *d, \
718 struct device_attribute *attr, char *b) \
719{ \
720 return loop_attr_show(d, b, loop_attr_##_name##_show); \
721} \
722static struct device_attribute loop_attr_##_name = \
723 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
724
725static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
726{
727 ssize_t ret;
728 char *p = NULL;
729
730 spin_lock_irq(&lo->lo_lock);
731 if (lo->lo_backing_file)
732 p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1);
733 spin_unlock_irq(&lo->lo_lock);
734
735 if (IS_ERR_OR_NULL(p))
736 ret = PTR_ERR(p);
737 else {
738 ret = strlen(p);
739 memmove(buf, p, ret);
740 buf[ret++] = '\n';
741 buf[ret] = 0;
742 }
743
744 return ret;
745}
746
747static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
748{
749 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
750}
751
752static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
753{
754 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
755}
756
757static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
758{
759 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
760
761 return sprintf(buf, "%s\n", autoclear ? "1" : "0");
762}
763
764static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
765{
766 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
767
768 return sprintf(buf, "%s\n", partscan ? "1" : "0");
769}
770
771static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf)
772{
773 int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO);
774
775 return sprintf(buf, "%s\n", dio ? "1" : "0");
776}
777
778LOOP_ATTR_RO(backing_file);
779LOOP_ATTR_RO(offset);
780LOOP_ATTR_RO(sizelimit);
781LOOP_ATTR_RO(autoclear);
782LOOP_ATTR_RO(partscan);
783LOOP_ATTR_RO(dio);
784
785static struct attribute *loop_attrs[] = {
786 &loop_attr_backing_file.attr,
787 &loop_attr_offset.attr,
788 &loop_attr_sizelimit.attr,
789 &loop_attr_autoclear.attr,
790 &loop_attr_partscan.attr,
791 &loop_attr_dio.attr,
792 NULL,
793};
794
795static struct attribute_group loop_attribute_group = {
796 .name = "loop",
797 .attrs= loop_attrs,
798};
799
800static int loop_sysfs_init(struct loop_device *lo)
801{
802 return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
803 &loop_attribute_group);
804}
805
806static void loop_sysfs_exit(struct loop_device *lo)
807{
808 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
809 &loop_attribute_group);
810}
811
812static void loop_config_discard(struct loop_device *lo)
813{
814 struct file *file = lo->lo_backing_file;
815 struct inode *inode = file->f_mapping->host;
816 struct request_queue *q = lo->lo_queue;
817
818 /*
819 * We use punch hole to reclaim the free space used by the
820 * image a.k.a. discard. However we do not support discard if
821 * encryption is enabled, because it may give an attacker
822 * useful information.
823 */
824 if ((!file->f_op->fallocate) ||
825 lo->lo_encrypt_key_size) {
826 q->limits.discard_granularity = 0;
827 q->limits.discard_alignment = 0;
828 blk_queue_max_discard_sectors(q, 0);
829 q->limits.discard_zeroes_data = 0;
830 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
831 return;
832 }
833
834 q->limits.discard_granularity = inode->i_sb->s_blocksize;
835 q->limits.discard_alignment = 0;
836 blk_queue_max_discard_sectors(q, UINT_MAX >> 9);
837 q->limits.discard_zeroes_data = 1;
838 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
839}
840
841static void loop_unprepare_queue(struct loop_device *lo)
842{
843 kthread_flush_worker(&lo->worker);
844 kthread_stop(lo->worker_task);
845}
846
847static int loop_prepare_queue(struct loop_device *lo)
848{
849 kthread_init_worker(&lo->worker);
850 lo->worker_task = kthread_run(kthread_worker_fn,
851 &lo->worker, "loop%d", lo->lo_number);
852 if (IS_ERR(lo->worker_task))
853 return -ENOMEM;
854 set_user_nice(lo->worker_task, MIN_NICE);
855 return 0;
856}
857
858static int loop_set_fd(struct loop_device *lo, fmode_t mode,
859 struct block_device *bdev, unsigned int arg)
860{
861 struct file *file, *f;
862 struct inode *inode;
863 struct address_space *mapping;
864 unsigned lo_blocksize;
865 int lo_flags = 0;
866 int error;
867 loff_t size;
868
869 /* This is safe, since we have a reference from open(). */
870 __module_get(THIS_MODULE);
871
872 error = -EBADF;
873 file = fget(arg);
874 if (!file)
875 goto out;
876
877 error = -EBUSY;
878 if (lo->lo_state != Lo_unbound)
879 goto out_putf;
880
881 /* Avoid recursion */
882 f = file;
883 while (is_loop_device(f)) {
884 struct loop_device *l;
885
886 if (f->f_mapping->host->i_bdev == bdev)
887 goto out_putf;
888
889 l = f->f_mapping->host->i_bdev->bd_disk->private_data;
890 if (l->lo_state == Lo_unbound) {
891 error = -EINVAL;
892 goto out_putf;
893 }
894 f = l->lo_backing_file;
895 }
896
897 mapping = file->f_mapping;
898 inode = mapping->host;
899
900 error = -EINVAL;
901 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
902 goto out_putf;
903
904 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
905 !file->f_op->write_iter)
906 lo_flags |= LO_FLAGS_READ_ONLY;
907
908 lo_blocksize = S_ISBLK(inode->i_mode) ?
909 inode->i_bdev->bd_block_size : PAGE_SIZE;
910
911 error = -EFBIG;
912 size = get_loop_size(lo, file);
913 if ((loff_t)(sector_t)size != size)
914 goto out_putf;
915 error = loop_prepare_queue(lo);
916 if (error)
917 goto out_putf;
918
919 error = 0;
920
921 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
922
923 lo->use_dio = false;
924 lo->lo_blocksize = lo_blocksize;
925 lo->lo_device = bdev;
926 lo->lo_flags = lo_flags;
927 lo->lo_backing_file = file;
928 lo->transfer = NULL;
929 lo->ioctl = NULL;
930 lo->lo_sizelimit = 0;
931 lo->old_gfp_mask = mapping_gfp_mask(mapping);
932 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
933
934 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
935 blk_queue_write_cache(lo->lo_queue, true, false);
936
937 loop_update_dio(lo);
938 set_capacity(lo->lo_disk, size);
939 bd_set_size(bdev, size << 9);
940 loop_sysfs_init(lo);
941 /* let user-space know about the new size */
942 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
943
944 set_blocksize(bdev, lo_blocksize);
945
946 lo->lo_state = Lo_bound;
947 if (part_shift)
948 lo->lo_flags |= LO_FLAGS_PARTSCAN;
949 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
950 loop_reread_partitions(lo, bdev);
951
952 /* Grab the block_device to prevent its destruction after we
953 * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev).
954 */
955 bdgrab(bdev);
956 return 0;
957
958 out_putf:
959 fput(file);
960 out:
961 /* This is safe: open() is still holding a reference. */
962 module_put(THIS_MODULE);
963 return error;
964}
965
966static int
967loop_release_xfer(struct loop_device *lo)
968{
969 int err = 0;
970 struct loop_func_table *xfer = lo->lo_encryption;
971
972 if (xfer) {
973 if (xfer->release)
974 err = xfer->release(lo);
975 lo->transfer = NULL;
976 lo->lo_encryption = NULL;
977 module_put(xfer->owner);
978 }
979 return err;
980}
981
982static int
983loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
984 const struct loop_info64 *i)
985{
986 int err = 0;
987
988 if (xfer) {
989 struct module *owner = xfer->owner;
990
991 if (!try_module_get(owner))
992 return -EINVAL;
993 if (xfer->init)
994 err = xfer->init(lo, i);
995 if (err)
996 module_put(owner);
997 else
998 lo->lo_encryption = xfer;
999 }
1000 return err;
1001}
1002
1003static int loop_clr_fd(struct loop_device *lo)
1004{
1005 struct file *filp = lo->lo_backing_file;
1006 gfp_t gfp = lo->old_gfp_mask;
1007 struct block_device *bdev = lo->lo_device;
1008
1009 if (lo->lo_state != Lo_bound)
1010 return -ENXIO;
1011
1012 /*
1013 * If we've explicitly asked to tear down the loop device,
1014 * and it has an elevated reference count, set it for auto-teardown when
1015 * the last reference goes away. This stops $!~#$@ udev from
1016 * preventing teardown because it decided that it needs to run blkid on
1017 * the loopback device whenever they appear. xfstests is notorious for
1018 * failing tests because blkid via udev races with a losetup
1019 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
1020 * command to fail with EBUSY.
1021 */
1022 if (atomic_read(&lo->lo_refcnt) > 1) {
1023 lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
1024 mutex_unlock(&lo->lo_ctl_mutex);
1025 return 0;
1026 }
1027
1028 if (filp == NULL)
1029 return -EINVAL;
1030
1031 /* freeze request queue during the transition */
1032 blk_mq_freeze_queue(lo->lo_queue);
1033
1034 spin_lock_irq(&lo->lo_lock);
1035 lo->lo_state = Lo_rundown;
1036 lo->lo_backing_file = NULL;
1037 spin_unlock_irq(&lo->lo_lock);
1038
1039 loop_release_xfer(lo);
1040 lo->transfer = NULL;
1041 lo->ioctl = NULL;
1042 lo->lo_device = NULL;
1043 lo->lo_encryption = NULL;
1044 lo->lo_offset = 0;
1045 lo->lo_sizelimit = 0;
1046 lo->lo_encrypt_key_size = 0;
1047 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
1048 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
1049 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1050 if (bdev) {
1051 bdput(bdev);
1052 invalidate_bdev(bdev);
1053 }
1054 set_capacity(lo->lo_disk, 0);
1055 loop_sysfs_exit(lo);
1056 if (bdev) {
1057 bd_set_size(bdev, 0);
1058 /* let user-space know about this change */
1059 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1060 }
1061 mapping_set_gfp_mask(filp->f_mapping, gfp);
1062 lo->lo_state = Lo_unbound;
1063 /* This is safe: open() is still holding a reference. */
1064 module_put(THIS_MODULE);
1065 blk_mq_unfreeze_queue(lo->lo_queue);
1066
1067 if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
1068 loop_reread_partitions(lo, bdev);
1069 lo->lo_flags = 0;
1070 if (!part_shift)
1071 lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
1072 loop_unprepare_queue(lo);
1073 mutex_unlock(&lo->lo_ctl_mutex);
1074 /*
1075 * Need not hold lo_ctl_mutex to fput backing file.
1076 * Calling fput holding lo_ctl_mutex triggers a circular
1077 * lock dependency possibility warning as fput can take
1078 * bd_mutex which is usually taken before lo_ctl_mutex.
1079 */
1080 fput(filp);
1081 return 0;
1082}
1083
1084static int
1085loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1086{
1087 int err;
1088 struct loop_func_table *xfer;
1089 kuid_t uid = current_uid();
1090
1091 if (lo->lo_encrypt_key_size &&
1092 !uid_eq(lo->lo_key_owner, uid) &&
1093 !capable(CAP_SYS_ADMIN))
1094 return -EPERM;
1095 if (lo->lo_state != Lo_bound)
1096 return -ENXIO;
1097 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
1098 return -EINVAL;
1099
1100 /* I/O need to be drained during transfer transition */
1101 blk_mq_freeze_queue(lo->lo_queue);
1102
1103 err = loop_release_xfer(lo);
1104 if (err)
1105 goto exit;
1106
1107 if (info->lo_encrypt_type) {
1108 unsigned int type = info->lo_encrypt_type;
1109
1110 if (type >= MAX_LO_CRYPT)
1111 return -EINVAL;
1112 xfer = xfer_funcs[type];
1113 if (xfer == NULL)
1114 return -EINVAL;
1115 } else
1116 xfer = NULL;
1117
1118 err = loop_init_xfer(lo, xfer, info);
1119 if (err)
1120 goto exit;
1121
1122 if (lo->lo_offset != info->lo_offset ||
1123 lo->lo_sizelimit != info->lo_sizelimit)
1124 if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit)) {
1125 err = -EFBIG;
1126 goto exit;
1127 }
1128
1129 loop_config_discard(lo);
1130
1131 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
1132 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
1133 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
1134 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
1135
1136 if (!xfer)
1137 xfer = &none_funcs;
1138 lo->transfer = xfer->transfer;
1139 lo->ioctl = xfer->ioctl;
1140
1141 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
1142 (info->lo_flags & LO_FLAGS_AUTOCLEAR))
1143 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
1144
1145 lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
1146 lo->lo_init[0] = info->lo_init[0];
1147 lo->lo_init[1] = info->lo_init[1];
1148 if (info->lo_encrypt_key_size) {
1149 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
1150 info->lo_encrypt_key_size);
1151 lo->lo_key_owner = uid;
1152 }
1153
1154 /* update dio if lo_offset or transfer is changed */
1155 __loop_update_dio(lo, lo->use_dio);
1156
1157 exit:
1158 blk_mq_unfreeze_queue(lo->lo_queue);
1159
1160 if (!err && (info->lo_flags & LO_FLAGS_PARTSCAN) &&
1161 !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
1162 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1163 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
1164 loop_reread_partitions(lo, lo->lo_device);
1165 }
1166
1167 return err;
1168}
1169
1170static int
1171loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1172{
1173 struct file *file = lo->lo_backing_file;
1174 struct kstat stat;
1175 int error;
1176
1177 if (lo->lo_state != Lo_bound)
1178 return -ENXIO;
1179 error = vfs_getattr(&file->f_path, &stat);
1180 if (error)
1181 return error;
1182 memset(info, 0, sizeof(*info));
1183 info->lo_number = lo->lo_number;
1184 info->lo_device = huge_encode_dev(stat.dev);
1185 info->lo_inode = stat.ino;
1186 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
1187 info->lo_offset = lo->lo_offset;
1188 info->lo_sizelimit = lo->lo_sizelimit;
1189 info->lo_flags = lo->lo_flags;
1190 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1191 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1192 info->lo_encrypt_type =
1193 lo->lo_encryption ? lo->lo_encryption->number : 0;
1194 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1195 info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1196 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1197 lo->lo_encrypt_key_size);
1198 }
1199 return 0;
1200}
1201
1202static void
1203loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1204{
1205 memset(info64, 0, sizeof(*info64));
1206 info64->lo_number = info->lo_number;
1207 info64->lo_device = info->lo_device;
1208 info64->lo_inode = info->lo_inode;
1209 info64->lo_rdevice = info->lo_rdevice;
1210 info64->lo_offset = info->lo_offset;
1211 info64->lo_sizelimit = 0;
1212 info64->lo_encrypt_type = info->lo_encrypt_type;
1213 info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1214 info64->lo_flags = info->lo_flags;
1215 info64->lo_init[0] = info->lo_init[0];
1216 info64->lo_init[1] = info->lo_init[1];
1217 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1218 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1219 else
1220 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1221 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1222}
1223
1224static int
1225loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1226{
1227 memset(info, 0, sizeof(*info));
1228 info->lo_number = info64->lo_number;
1229 info->lo_device = info64->lo_device;
1230 info->lo_inode = info64->lo_inode;
1231 info->lo_rdevice = info64->lo_rdevice;
1232 info->lo_offset = info64->lo_offset;
1233 info->lo_encrypt_type = info64->lo_encrypt_type;
1234 info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1235 info->lo_flags = info64->lo_flags;
1236 info->lo_init[0] = info64->lo_init[0];
1237 info->lo_init[1] = info64->lo_init[1];
1238 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1239 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1240 else
1241 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1242 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1243
1244 /* error in case values were truncated */
1245 if (info->lo_device != info64->lo_device ||
1246 info->lo_rdevice != info64->lo_rdevice ||
1247 info->lo_inode != info64->lo_inode ||
1248 info->lo_offset != info64->lo_offset)
1249 return -EOVERFLOW;
1250
1251 return 0;
1252}
1253
1254static int
1255loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1256{
1257 struct loop_info info;
1258 struct loop_info64 info64;
1259
1260 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1261 return -EFAULT;
1262 loop_info64_from_old(&info, &info64);
1263 return loop_set_status(lo, &info64);
1264}
1265
1266static int
1267loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1268{
1269 struct loop_info64 info64;
1270
1271 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1272 return -EFAULT;
1273 return loop_set_status(lo, &info64);
1274}
1275
1276static int
1277loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1278 struct loop_info info;
1279 struct loop_info64 info64;
1280 int err = 0;
1281
1282 if (!arg)
1283 err = -EINVAL;
1284 if (!err)
1285 err = loop_get_status(lo, &info64);
1286 if (!err)
1287 err = loop_info64_to_old(&info64, &info);
1288 if (!err && copy_to_user(arg, &info, sizeof(info)))
1289 err = -EFAULT;
1290
1291 return err;
1292}
1293
1294static int
1295loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1296 struct loop_info64 info64;
1297 int err = 0;
1298
1299 if (!arg)
1300 err = -EINVAL;
1301 if (!err)
1302 err = loop_get_status(lo, &info64);
1303 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1304 err = -EFAULT;
1305
1306 return err;
1307}
1308
1309static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
1310{
1311 if (unlikely(lo->lo_state != Lo_bound))
1312 return -ENXIO;
1313
1314 return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
1315}
1316
1317static int loop_set_dio(struct loop_device *lo, unsigned long arg)
1318{
1319 int error = -ENXIO;
1320 if (lo->lo_state != Lo_bound)
1321 goto out;
1322
1323 __loop_update_dio(lo, !!arg);
1324 if (lo->use_dio == !!arg)
1325 return 0;
1326 error = -EINVAL;
1327 out:
1328 return error;
1329}
1330
1331static int lo_ioctl(struct block_device *bdev, fmode_t mode,
1332 unsigned int cmd, unsigned long arg)
1333{
1334 struct loop_device *lo = bdev->bd_disk->private_data;
1335 int err;
1336
1337 mutex_lock_nested(&lo->lo_ctl_mutex, 1);
1338 switch (cmd) {
1339 case LOOP_SET_FD:
1340 err = loop_set_fd(lo, mode, bdev, arg);
1341 break;
1342 case LOOP_CHANGE_FD:
1343 err = loop_change_fd(lo, bdev, arg);
1344 break;
1345 case LOOP_CLR_FD:
1346 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1347 err = loop_clr_fd(lo);
1348 if (!err)
1349 goto out_unlocked;
1350 break;
1351 case LOOP_SET_STATUS:
1352 err = -EPERM;
1353 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1354 err = loop_set_status_old(lo,
1355 (struct loop_info __user *)arg);
1356 break;
1357 case LOOP_GET_STATUS:
1358 err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1359 break;
1360 case LOOP_SET_STATUS64:
1361 err = -EPERM;
1362 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1363 err = loop_set_status64(lo,
1364 (struct loop_info64 __user *) arg);
1365 break;
1366 case LOOP_GET_STATUS64:
1367 err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1368 break;
1369 case LOOP_SET_CAPACITY:
1370 err = -EPERM;
1371 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1372 err = loop_set_capacity(lo, bdev);
1373 break;
1374 case LOOP_SET_DIRECT_IO:
1375 err = -EPERM;
1376 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1377 err = loop_set_dio(lo, arg);
1378 break;
1379 default:
1380 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1381 }
1382 mutex_unlock(&lo->lo_ctl_mutex);
1383
1384out_unlocked:
1385 return err;
1386}
1387
1388#ifdef CONFIG_COMPAT
1389struct compat_loop_info {
1390 compat_int_t lo_number; /* ioctl r/o */
1391 compat_dev_t lo_device; /* ioctl r/o */
1392 compat_ulong_t lo_inode; /* ioctl r/o */
1393 compat_dev_t lo_rdevice; /* ioctl r/o */
1394 compat_int_t lo_offset;
1395 compat_int_t lo_encrypt_type;
1396 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1397 compat_int_t lo_flags; /* ioctl r/o */
1398 char lo_name[LO_NAME_SIZE];
1399 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1400 compat_ulong_t lo_init[2];
1401 char reserved[4];
1402};
1403
1404/*
1405 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1406 * - noinlined to reduce stack space usage in main part of driver
1407 */
1408static noinline int
1409loop_info64_from_compat(const struct compat_loop_info __user *arg,
1410 struct loop_info64 *info64)
1411{
1412 struct compat_loop_info info;
1413
1414 if (copy_from_user(&info, arg, sizeof(info)))
1415 return -EFAULT;
1416
1417 memset(info64, 0, sizeof(*info64));
1418 info64->lo_number = info.lo_number;
1419 info64->lo_device = info.lo_device;
1420 info64->lo_inode = info.lo_inode;
1421 info64->lo_rdevice = info.lo_rdevice;
1422 info64->lo_offset = info.lo_offset;
1423 info64->lo_sizelimit = 0;
1424 info64->lo_encrypt_type = info.lo_encrypt_type;
1425 info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1426 info64->lo_flags = info.lo_flags;
1427 info64->lo_init[0] = info.lo_init[0];
1428 info64->lo_init[1] = info.lo_init[1];
1429 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1430 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1431 else
1432 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1433 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1434 return 0;
1435}
1436
1437/*
1438 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1439 * - noinlined to reduce stack space usage in main part of driver
1440 */
1441static noinline int
1442loop_info64_to_compat(const struct loop_info64 *info64,
1443 struct compat_loop_info __user *arg)
1444{
1445 struct compat_loop_info info;
1446
1447 memset(&info, 0, sizeof(info));
1448 info.lo_number = info64->lo_number;
1449 info.lo_device = info64->lo_device;
1450 info.lo_inode = info64->lo_inode;
1451 info.lo_rdevice = info64->lo_rdevice;
1452 info.lo_offset = info64->lo_offset;
1453 info.lo_encrypt_type = info64->lo_encrypt_type;
1454 info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
1455 info.lo_flags = info64->lo_flags;
1456 info.lo_init[0] = info64->lo_init[0];
1457 info.lo_init[1] = info64->lo_init[1];
1458 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1459 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1460 else
1461 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1462 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1463
1464 /* error in case values were truncated */
1465 if (info.lo_device != info64->lo_device ||
1466 info.lo_rdevice != info64->lo_rdevice ||
1467 info.lo_inode != info64->lo_inode ||
1468 info.lo_offset != info64->lo_offset ||
1469 info.lo_init[0] != info64->lo_init[0] ||
1470 info.lo_init[1] != info64->lo_init[1])
1471 return -EOVERFLOW;
1472
1473 if (copy_to_user(arg, &info, sizeof(info)))
1474 return -EFAULT;
1475 return 0;
1476}
1477
1478static int
1479loop_set_status_compat(struct loop_device *lo,
1480 const struct compat_loop_info __user *arg)
1481{
1482 struct loop_info64 info64;
1483 int ret;
1484
1485 ret = loop_info64_from_compat(arg, &info64);
1486 if (ret < 0)
1487 return ret;
1488 return loop_set_status(lo, &info64);
1489}
1490
1491static int
1492loop_get_status_compat(struct loop_device *lo,
1493 struct compat_loop_info __user *arg)
1494{
1495 struct loop_info64 info64;
1496 int err = 0;
1497
1498 if (!arg)
1499 err = -EINVAL;
1500 if (!err)
1501 err = loop_get_status(lo, &info64);
1502 if (!err)
1503 err = loop_info64_to_compat(&info64, arg);
1504 return err;
1505}
1506
1507static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1508 unsigned int cmd, unsigned long arg)
1509{
1510 struct loop_device *lo = bdev->bd_disk->private_data;
1511 int err;
1512
1513 switch(cmd) {
1514 case LOOP_SET_STATUS:
1515 mutex_lock(&lo->lo_ctl_mutex);
1516 err = loop_set_status_compat(
1517 lo, (const struct compat_loop_info __user *) arg);
1518 mutex_unlock(&lo->lo_ctl_mutex);
1519 break;
1520 case LOOP_GET_STATUS:
1521 mutex_lock(&lo->lo_ctl_mutex);
1522 err = loop_get_status_compat(
1523 lo, (struct compat_loop_info __user *) arg);
1524 mutex_unlock(&lo->lo_ctl_mutex);
1525 break;
1526 case LOOP_SET_CAPACITY:
1527 case LOOP_CLR_FD:
1528 case LOOP_GET_STATUS64:
1529 case LOOP_SET_STATUS64:
1530 arg = (unsigned long) compat_ptr(arg);
1531 case LOOP_SET_FD:
1532 case LOOP_CHANGE_FD:
1533 err = lo_ioctl(bdev, mode, cmd, arg);
1534 break;
1535 default:
1536 err = -ENOIOCTLCMD;
1537 break;
1538 }
1539 return err;
1540}
1541#endif
1542
1543static int lo_open(struct block_device *bdev, fmode_t mode)
1544{
1545 struct loop_device *lo;
1546 int err = 0;
1547
1548 mutex_lock(&loop_index_mutex);
1549 lo = bdev->bd_disk->private_data;
1550 if (!lo) {
1551 err = -ENXIO;
1552 goto out;
1553 }
1554
1555 atomic_inc(&lo->lo_refcnt);
1556out:
1557 mutex_unlock(&loop_index_mutex);
1558 return err;
1559}
1560
1561static void lo_release(struct gendisk *disk, fmode_t mode)
1562{
1563 struct loop_device *lo = disk->private_data;
1564 int err;
1565
1566 if (atomic_dec_return(&lo->lo_refcnt))
1567 return;
1568
1569 mutex_lock(&lo->lo_ctl_mutex);
1570 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
1571 /*
1572 * In autoclear mode, stop the loop thread
1573 * and remove configuration after last close.
1574 */
1575 err = loop_clr_fd(lo);
1576 if (!err)
1577 return;
1578 } else {
1579 /*
1580 * Otherwise keep thread (if running) and config,
1581 * but flush possible ongoing bios in thread.
1582 */
1583 loop_flush(lo);
1584 }
1585
1586 mutex_unlock(&lo->lo_ctl_mutex);
1587}
1588
1589static const struct block_device_operations lo_fops = {
1590 .owner = THIS_MODULE,
1591 .open = lo_open,
1592 .release = lo_release,
1593 .ioctl = lo_ioctl,
1594#ifdef CONFIG_COMPAT
1595 .compat_ioctl = lo_compat_ioctl,
1596#endif
1597};
1598
1599/*
1600 * And now the modules code and kernel interface.
1601 */
1602static int max_loop;
1603module_param(max_loop, int, S_IRUGO);
1604MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1605module_param(max_part, int, S_IRUGO);
1606MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1607MODULE_LICENSE("GPL");
1608MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1609
1610int loop_register_transfer(struct loop_func_table *funcs)
1611{
1612 unsigned int n = funcs->number;
1613
1614 if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1615 return -EINVAL;
1616 xfer_funcs[n] = funcs;
1617 return 0;
1618}
1619
1620static int unregister_transfer_cb(int id, void *ptr, void *data)
1621{
1622 struct loop_device *lo = ptr;
1623 struct loop_func_table *xfer = data;
1624
1625 mutex_lock(&lo->lo_ctl_mutex);
1626 if (lo->lo_encryption == xfer)
1627 loop_release_xfer(lo);
1628 mutex_unlock(&lo->lo_ctl_mutex);
1629 return 0;
1630}
1631
1632int loop_unregister_transfer(int number)
1633{
1634 unsigned int n = number;
1635 struct loop_func_table *xfer;
1636
1637 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1638 return -EINVAL;
1639
1640 xfer_funcs[n] = NULL;
1641 idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
1642 return 0;
1643}
1644
1645EXPORT_SYMBOL(loop_register_transfer);
1646EXPORT_SYMBOL(loop_unregister_transfer);
1647
1648static int loop_queue_rq(struct blk_mq_hw_ctx *hctx,
1649 const struct blk_mq_queue_data *bd)
1650{
1651 struct loop_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
1652 struct loop_device *lo = cmd->rq->q->queuedata;
1653
1654 blk_mq_start_request(bd->rq);
1655
1656 if (lo->lo_state != Lo_bound)
1657 return BLK_MQ_RQ_QUEUE_ERROR;
1658
1659 switch (req_op(cmd->rq)) {
1660 case REQ_OP_FLUSH:
1661 case REQ_OP_DISCARD:
1662 cmd->use_aio = false;
1663 break;
1664 default:
1665 cmd->use_aio = lo->use_dio;
1666 break;
1667 }
1668
1669 kthread_queue_work(&lo->worker, &cmd->work);
1670
1671 return BLK_MQ_RQ_QUEUE_OK;
1672}
1673
1674static void loop_handle_cmd(struct loop_cmd *cmd)
1675{
1676 const bool write = op_is_write(req_op(cmd->rq));
1677 struct loop_device *lo = cmd->rq->q->queuedata;
1678 int ret = 0;
1679
1680 if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) {
1681 ret = -EIO;
1682 goto failed;
1683 }
1684
1685 ret = do_req_filebacked(lo, cmd->rq);
1686 failed:
1687 /* complete non-aio request */
1688 if (!cmd->use_aio || ret)
1689 blk_mq_complete_request(cmd->rq, ret ? -EIO : 0);
1690}
1691
1692static void loop_queue_work(struct kthread_work *work)
1693{
1694 struct loop_cmd *cmd =
1695 container_of(work, struct loop_cmd, work);
1696
1697 loop_handle_cmd(cmd);
1698}
1699
1700static int loop_init_request(void *data, struct request *rq,
1701 unsigned int hctx_idx, unsigned int request_idx,
1702 unsigned int numa_node)
1703{
1704 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
1705
1706 cmd->rq = rq;
1707 kthread_init_work(&cmd->work, loop_queue_work);
1708
1709 return 0;
1710}
1711
1712static struct blk_mq_ops loop_mq_ops = {
1713 .queue_rq = loop_queue_rq,
1714 .init_request = loop_init_request,
1715};
1716
1717static int loop_add(struct loop_device **l, int i)
1718{
1719 struct loop_device *lo;
1720 struct gendisk *disk;
1721 int err;
1722
1723 err = -ENOMEM;
1724 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1725 if (!lo)
1726 goto out;
1727
1728 lo->lo_state = Lo_unbound;
1729
1730 /* allocate id, if @id >= 0, we're requesting that specific id */
1731 if (i >= 0) {
1732 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
1733 if (err == -ENOSPC)
1734 err = -EEXIST;
1735 } else {
1736 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
1737 }
1738 if (err < 0)
1739 goto out_free_dev;
1740 i = err;
1741
1742 err = -ENOMEM;
1743 lo->tag_set.ops = &loop_mq_ops;
1744 lo->tag_set.nr_hw_queues = 1;
1745 lo->tag_set.queue_depth = 128;
1746 lo->tag_set.numa_node = NUMA_NO_NODE;
1747 lo->tag_set.cmd_size = sizeof(struct loop_cmd);
1748 lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
1749 lo->tag_set.driver_data = lo;
1750
1751 err = blk_mq_alloc_tag_set(&lo->tag_set);
1752 if (err)
1753 goto out_free_idr;
1754
1755 lo->lo_queue = blk_mq_init_queue(&lo->tag_set);
1756 if (IS_ERR_OR_NULL(lo->lo_queue)) {
1757 err = PTR_ERR(lo->lo_queue);
1758 goto out_cleanup_tags;
1759 }
1760 lo->lo_queue->queuedata = lo;
1761
1762 /*
1763 * It doesn't make sense to enable merge because the I/O
1764 * submitted to backing file is handled page by page.
1765 */
1766 queue_flag_set_unlocked(QUEUE_FLAG_NOMERGES, lo->lo_queue);
1767
1768 err = -ENOMEM;
1769 disk = lo->lo_disk = alloc_disk(1 << part_shift);
1770 if (!disk)
1771 goto out_free_queue;
1772
1773 /*
1774 * Disable partition scanning by default. The in-kernel partition
1775 * scanning can be requested individually per-device during its
1776 * setup. Userspace can always add and remove partitions from all
1777 * devices. The needed partition minors are allocated from the
1778 * extended minor space, the main loop device numbers will continue
1779 * to match the loop minors, regardless of the number of partitions
1780 * used.
1781 *
1782 * If max_part is given, partition scanning is globally enabled for
1783 * all loop devices. The minors for the main loop devices will be
1784 * multiples of max_part.
1785 *
1786 * Note: Global-for-all-devices, set-only-at-init, read-only module
1787 * parameteters like 'max_loop' and 'max_part' make things needlessly
1788 * complicated, are too static, inflexible and may surprise
1789 * userspace tools. Parameters like this in general should be avoided.
1790 */
1791 if (!part_shift)
1792 disk->flags |= GENHD_FL_NO_PART_SCAN;
1793 disk->flags |= GENHD_FL_EXT_DEVT;
1794 mutex_init(&lo->lo_ctl_mutex);
1795 atomic_set(&lo->lo_refcnt, 0);
1796 lo->lo_number = i;
1797 spin_lock_init(&lo->lo_lock);
1798 disk->major = LOOP_MAJOR;
1799 disk->first_minor = i << part_shift;
1800 disk->fops = &lo_fops;
1801 disk->private_data = lo;
1802 disk->queue = lo->lo_queue;
1803 sprintf(disk->disk_name, "loop%d", i);
1804 add_disk(disk);
1805 *l = lo;
1806 return lo->lo_number;
1807
1808out_free_queue:
1809 blk_cleanup_queue(lo->lo_queue);
1810out_cleanup_tags:
1811 blk_mq_free_tag_set(&lo->tag_set);
1812out_free_idr:
1813 idr_remove(&loop_index_idr, i);
1814out_free_dev:
1815 kfree(lo);
1816out:
1817 return err;
1818}
1819
1820static void loop_remove(struct loop_device *lo)
1821{
1822 blk_cleanup_queue(lo->lo_queue);
1823 del_gendisk(lo->lo_disk);
1824 blk_mq_free_tag_set(&lo->tag_set);
1825 put_disk(lo->lo_disk);
1826 kfree(lo);
1827}
1828
1829static int find_free_cb(int id, void *ptr, void *data)
1830{
1831 struct loop_device *lo = ptr;
1832 struct loop_device **l = data;
1833
1834 if (lo->lo_state == Lo_unbound) {
1835 *l = lo;
1836 return 1;
1837 }
1838 return 0;
1839}
1840
1841static int loop_lookup(struct loop_device **l, int i)
1842{
1843 struct loop_device *lo;
1844 int ret = -ENODEV;
1845
1846 if (i < 0) {
1847 int err;
1848
1849 err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
1850 if (err == 1) {
1851 *l = lo;
1852 ret = lo->lo_number;
1853 }
1854 goto out;
1855 }
1856
1857 /* lookup and return a specific i */
1858 lo = idr_find(&loop_index_idr, i);
1859 if (lo) {
1860 *l = lo;
1861 ret = lo->lo_number;
1862 }
1863out:
1864 return ret;
1865}
1866
1867static struct kobject *loop_probe(dev_t dev, int *part, void *data)
1868{
1869 struct loop_device *lo;
1870 struct kobject *kobj;
1871 int err;
1872
1873 mutex_lock(&loop_index_mutex);
1874 err = loop_lookup(&lo, MINOR(dev) >> part_shift);
1875 if (err < 0)
1876 err = loop_add(&lo, MINOR(dev) >> part_shift);
1877 if (err < 0)
1878 kobj = NULL;
1879 else
1880 kobj = get_disk(lo->lo_disk);
1881 mutex_unlock(&loop_index_mutex);
1882
1883 *part = 0;
1884 return kobj;
1885}
1886
1887static long loop_control_ioctl(struct file *file, unsigned int cmd,
1888 unsigned long parm)
1889{
1890 struct loop_device *lo;
1891 int ret = -ENOSYS;
1892
1893 mutex_lock(&loop_index_mutex);
1894 switch (cmd) {
1895 case LOOP_CTL_ADD:
1896 ret = loop_lookup(&lo, parm);
1897 if (ret >= 0) {
1898 ret = -EEXIST;
1899 break;
1900 }
1901 ret = loop_add(&lo, parm);
1902 break;
1903 case LOOP_CTL_REMOVE:
1904 ret = loop_lookup(&lo, parm);
1905 if (ret < 0)
1906 break;
1907 mutex_lock(&lo->lo_ctl_mutex);
1908 if (lo->lo_state != Lo_unbound) {
1909 ret = -EBUSY;
1910 mutex_unlock(&lo->lo_ctl_mutex);
1911 break;
1912 }
1913 if (atomic_read(&lo->lo_refcnt) > 0) {
1914 ret = -EBUSY;
1915 mutex_unlock(&lo->lo_ctl_mutex);
1916 break;
1917 }
1918 lo->lo_disk->private_data = NULL;
1919 mutex_unlock(&lo->lo_ctl_mutex);
1920 idr_remove(&loop_index_idr, lo->lo_number);
1921 loop_remove(lo);
1922 break;
1923 case LOOP_CTL_GET_FREE:
1924 ret = loop_lookup(&lo, -1);
1925 if (ret >= 0)
1926 break;
1927 ret = loop_add(&lo, -1);
1928 }
1929 mutex_unlock(&loop_index_mutex);
1930
1931 return ret;
1932}
1933
1934static const struct file_operations loop_ctl_fops = {
1935 .open = nonseekable_open,
1936 .unlocked_ioctl = loop_control_ioctl,
1937 .compat_ioctl = loop_control_ioctl,
1938 .owner = THIS_MODULE,
1939 .llseek = noop_llseek,
1940};
1941
1942static struct miscdevice loop_misc = {
1943 .minor = LOOP_CTRL_MINOR,
1944 .name = "loop-control",
1945 .fops = &loop_ctl_fops,
1946};
1947
1948MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
1949MODULE_ALIAS("devname:loop-control");
1950
1951static int __init loop_init(void)
1952{
1953 int i, nr;
1954 unsigned long range;
1955 struct loop_device *lo;
1956 int err;
1957
1958 err = misc_register(&loop_misc);
1959 if (err < 0)
1960 return err;
1961
1962 part_shift = 0;
1963 if (max_part > 0) {
1964 part_shift = fls(max_part);
1965
1966 /*
1967 * Adjust max_part according to part_shift as it is exported
1968 * to user space so that user can decide correct minor number
1969 * if [s]he want to create more devices.
1970 *
1971 * Note that -1 is required because partition 0 is reserved
1972 * for the whole disk.
1973 */
1974 max_part = (1UL << part_shift) - 1;
1975 }
1976
1977 if ((1UL << part_shift) > DISK_MAX_PARTS) {
1978 err = -EINVAL;
1979 goto misc_out;
1980 }
1981
1982 if (max_loop > 1UL << (MINORBITS - part_shift)) {
1983 err = -EINVAL;
1984 goto misc_out;
1985 }
1986
1987 /*
1988 * If max_loop is specified, create that many devices upfront.
1989 * This also becomes a hard limit. If max_loop is not specified,
1990 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1991 * init time. Loop devices can be requested on-demand with the
1992 * /dev/loop-control interface, or be instantiated by accessing
1993 * a 'dead' device node.
1994 */
1995 if (max_loop) {
1996 nr = max_loop;
1997 range = max_loop << part_shift;
1998 } else {
1999 nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
2000 range = 1UL << MINORBITS;
2001 }
2002
2003 if (register_blkdev(LOOP_MAJOR, "loop")) {
2004 err = -EIO;
2005 goto misc_out;
2006 }
2007
2008 blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
2009 THIS_MODULE, loop_probe, NULL, NULL);
2010
2011 /* pre-create number of devices given by config or max_loop */
2012 mutex_lock(&loop_index_mutex);
2013 for (i = 0; i < nr; i++)
2014 loop_add(&lo, i);
2015 mutex_unlock(&loop_index_mutex);
2016
2017 printk(KERN_INFO "loop: module loaded\n");
2018 return 0;
2019
2020misc_out:
2021 misc_deregister(&loop_misc);
2022 return err;
2023}
2024
2025static int loop_exit_cb(int id, void *ptr, void *data)
2026{
2027 struct loop_device *lo = ptr;
2028
2029 loop_remove(lo);
2030 return 0;
2031}
2032
2033static void __exit loop_exit(void)
2034{
2035 unsigned long range;
2036
2037 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
2038
2039 idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
2040 idr_destroy(&loop_index_idr);
2041
2042 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
2043 unregister_blkdev(LOOP_MAJOR, "loop");
2044
2045 misc_deregister(&loop_misc);
2046}
2047
2048module_init(loop_init);
2049module_exit(loop_exit);
2050
2051#ifndef MODULE
2052static int __init max_loop_setup(char *str)
2053{
2054 max_loop = simple_strtol(str, NULL, 0);
2055 return 1;
2056}
2057
2058__setup("max_loop=", max_loop_setup);
2059#endif