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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/loop.h>
67#include <linux/compat.h>
68#include <linux/suspend.h>
69#include <linux/freezer.h>
70#include <linux/mutex.h>
71#include <linux/writeback.h>
72#include <linux/completion.h>
73#include <linux/highmem.h>
74#include <linux/kthread.h>
75#include <linux/splice.h>
76#include <linux/sysfs.h>
77#include <linux/miscdevice.h>
78#include <linux/falloc.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 size, loopsize;
166
167 /* Compute loopsize in bytes */
168 size = i_size_read(file->f_mapping->host);
169 loopsize = size - offset;
170 /* offset is beyond i_size, wierd but possible */
171 if (loopsize < 0)
172 return 0;
173
174 if (sizelimit > 0 && sizelimit < loopsize)
175 loopsize = sizelimit;
176 /*
177 * Unfortunately, if we want to do I/O on the device,
178 * the number of 512-byte sectors has to fit into a sector_t.
179 */
180 return loopsize >> 9;
181}
182
183static loff_t get_loop_size(struct loop_device *lo, struct file *file)
184{
185 return get_size(lo->lo_offset, lo->lo_sizelimit, file);
186}
187
188static int
189figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
190{
191 loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
192 sector_t x = (sector_t)size;
193
194 if (unlikely((loff_t)x != size))
195 return -EFBIG;
196 if (lo->lo_offset != offset)
197 lo->lo_offset = offset;
198 if (lo->lo_sizelimit != sizelimit)
199 lo->lo_sizelimit = sizelimit;
200 set_capacity(lo->lo_disk, x);
201 return 0;
202}
203
204static inline int
205lo_do_transfer(struct loop_device *lo, int cmd,
206 struct page *rpage, unsigned roffs,
207 struct page *lpage, unsigned loffs,
208 int size, sector_t rblock)
209{
210 if (unlikely(!lo->transfer))
211 return 0;
212
213 return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
214}
215
216/**
217 * __do_lo_send_write - helper for writing data to a loop device
218 *
219 * This helper just factors out common code between do_lo_send_direct_write()
220 * and do_lo_send_write().
221 */
222static int __do_lo_send_write(struct file *file,
223 u8 *buf, const int len, loff_t pos)
224{
225 ssize_t bw;
226 mm_segment_t old_fs = get_fs();
227
228 set_fs(get_ds());
229 bw = file->f_op->write(file, buf, len, &pos);
230 set_fs(old_fs);
231 if (likely(bw == len))
232 return 0;
233 printk(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
234 (unsigned long long)pos, len);
235 if (bw >= 0)
236 bw = -EIO;
237 return bw;
238}
239
240/**
241 * do_lo_send_direct_write - helper for writing data to a loop device
242 *
243 * This is the fast, non-transforming version that does not need double
244 * buffering.
245 */
246static int do_lo_send_direct_write(struct loop_device *lo,
247 struct bio_vec *bvec, loff_t pos, struct page *page)
248{
249 ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
250 kmap(bvec->bv_page) + bvec->bv_offset,
251 bvec->bv_len, pos);
252 kunmap(bvec->bv_page);
253 cond_resched();
254 return bw;
255}
256
257/**
258 * do_lo_send_write - helper for writing data to a loop device
259 *
260 * This is the slow, transforming version that needs to double buffer the
261 * data as it cannot do the transformations in place without having direct
262 * access to the destination pages of the backing file.
263 */
264static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
265 loff_t pos, struct page *page)
266{
267 int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
268 bvec->bv_offset, bvec->bv_len, pos >> 9);
269 if (likely(!ret))
270 return __do_lo_send_write(lo->lo_backing_file,
271 page_address(page), bvec->bv_len,
272 pos);
273 printk(KERN_ERR "loop: Transfer error at byte offset %llu, "
274 "length %i.\n", (unsigned long long)pos, bvec->bv_len);
275 if (ret > 0)
276 ret = -EIO;
277 return ret;
278}
279
280static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos)
281{
282 int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t,
283 struct page *page);
284 struct bio_vec *bvec;
285 struct page *page = NULL;
286 int i, ret = 0;
287
288 if (lo->transfer != transfer_none) {
289 page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
290 if (unlikely(!page))
291 goto fail;
292 kmap(page);
293 do_lo_send = do_lo_send_write;
294 } else {
295 do_lo_send = do_lo_send_direct_write;
296 }
297
298 bio_for_each_segment(bvec, bio, i) {
299 ret = do_lo_send(lo, bvec, pos, page);
300 if (ret < 0)
301 break;
302 pos += bvec->bv_len;
303 }
304 if (page) {
305 kunmap(page);
306 __free_page(page);
307 }
308out:
309 return ret;
310fail:
311 printk(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
312 ret = -ENOMEM;
313 goto out;
314}
315
316struct lo_read_data {
317 struct loop_device *lo;
318 struct page *page;
319 unsigned offset;
320 int bsize;
321};
322
323static int
324lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
325 struct splice_desc *sd)
326{
327 struct lo_read_data *p = sd->u.data;
328 struct loop_device *lo = p->lo;
329 struct page *page = buf->page;
330 sector_t IV;
331 int size;
332
333 IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) +
334 (buf->offset >> 9);
335 size = sd->len;
336 if (size > p->bsize)
337 size = p->bsize;
338
339 if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) {
340 printk(KERN_ERR "loop: transfer error block %ld\n",
341 page->index);
342 size = -EINVAL;
343 }
344
345 flush_dcache_page(p->page);
346
347 if (size > 0)
348 p->offset += size;
349
350 return size;
351}
352
353static int
354lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd)
355{
356 return __splice_from_pipe(pipe, sd, lo_splice_actor);
357}
358
359static ssize_t
360do_lo_receive(struct loop_device *lo,
361 struct bio_vec *bvec, int bsize, loff_t pos)
362{
363 struct lo_read_data cookie;
364 struct splice_desc sd;
365 struct file *file;
366 ssize_t retval;
367
368 cookie.lo = lo;
369 cookie.page = bvec->bv_page;
370 cookie.offset = bvec->bv_offset;
371 cookie.bsize = bsize;
372
373 sd.len = 0;
374 sd.total_len = bvec->bv_len;
375 sd.flags = 0;
376 sd.pos = pos;
377 sd.u.data = &cookie;
378
379 file = lo->lo_backing_file;
380 retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);
381
382 return retval;
383}
384
385static int
386lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos)
387{
388 struct bio_vec *bvec;
389 ssize_t s;
390 int i;
391
392 bio_for_each_segment(bvec, bio, i) {
393 s = do_lo_receive(lo, bvec, bsize, pos);
394 if (s < 0)
395 return s;
396
397 if (s != bvec->bv_len) {
398 zero_fill_bio(bio);
399 break;
400 }
401 pos += bvec->bv_len;
402 }
403 return 0;
404}
405
406static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
407{
408 loff_t pos;
409 int ret;
410
411 pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
412
413 if (bio_rw(bio) == WRITE) {
414 struct file *file = lo->lo_backing_file;
415
416 if (bio->bi_rw & REQ_FLUSH) {
417 ret = vfs_fsync(file, 0);
418 if (unlikely(ret && ret != -EINVAL)) {
419 ret = -EIO;
420 goto out;
421 }
422 }
423
424 /*
425 * We use punch hole to reclaim the free space used by the
426 * image a.k.a. discard. However we do not support discard if
427 * encryption is enabled, because it may give an attacker
428 * useful information.
429 */
430 if (bio->bi_rw & REQ_DISCARD) {
431 struct file *file = lo->lo_backing_file;
432 int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
433
434 if ((!file->f_op->fallocate) ||
435 lo->lo_encrypt_key_size) {
436 ret = -EOPNOTSUPP;
437 goto out;
438 }
439 ret = file->f_op->fallocate(file, mode, pos,
440 bio->bi_size);
441 if (unlikely(ret && ret != -EINVAL &&
442 ret != -EOPNOTSUPP))
443 ret = -EIO;
444 goto out;
445 }
446
447 ret = lo_send(lo, bio, pos);
448
449 if ((bio->bi_rw & REQ_FUA) && !ret) {
450 ret = vfs_fsync(file, 0);
451 if (unlikely(ret && ret != -EINVAL))
452 ret = -EIO;
453 }
454 } else
455 ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
456
457out:
458 return ret;
459}
460
461/*
462 * Add bio to back of pending list
463 */
464static void loop_add_bio(struct loop_device *lo, struct bio *bio)
465{
466 bio_list_add(&lo->lo_bio_list, bio);
467}
468
469/*
470 * Grab first pending buffer
471 */
472static struct bio *loop_get_bio(struct loop_device *lo)
473{
474 return bio_list_pop(&lo->lo_bio_list);
475}
476
477static void loop_make_request(struct request_queue *q, struct bio *old_bio)
478{
479 struct loop_device *lo = q->queuedata;
480 int rw = bio_rw(old_bio);
481
482 if (rw == READA)
483 rw = READ;
484
485 BUG_ON(!lo || (rw != READ && rw != WRITE));
486
487 spin_lock_irq(&lo->lo_lock);
488 if (lo->lo_state != Lo_bound)
489 goto out;
490 if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))
491 goto out;
492 loop_add_bio(lo, old_bio);
493 wake_up(&lo->lo_event);
494 spin_unlock_irq(&lo->lo_lock);
495 return;
496
497out:
498 spin_unlock_irq(&lo->lo_lock);
499 bio_io_error(old_bio);
500}
501
502struct switch_request {
503 struct file *file;
504 struct completion wait;
505};
506
507static void do_loop_switch(struct loop_device *, struct switch_request *);
508
509static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio)
510{
511 if (unlikely(!bio->bi_bdev)) {
512 do_loop_switch(lo, bio->bi_private);
513 bio_put(bio);
514 } else {
515 int ret = do_bio_filebacked(lo, bio);
516 bio_endio(bio, ret);
517 }
518}
519
520/*
521 * worker thread that handles reads/writes to file backed loop devices,
522 * to avoid blocking in our make_request_fn. it also does loop decrypting
523 * on reads for block backed loop, as that is too heavy to do from
524 * b_end_io context where irqs may be disabled.
525 *
526 * Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before
527 * calling kthread_stop(). Therefore once kthread_should_stop() is
528 * true, make_request will not place any more requests. Therefore
529 * once kthread_should_stop() is true and lo_bio is NULL, we are
530 * done with the loop.
531 */
532static int loop_thread(void *data)
533{
534 struct loop_device *lo = data;
535 struct bio *bio;
536
537 set_user_nice(current, -20);
538
539 while (!kthread_should_stop() || !bio_list_empty(&lo->lo_bio_list)) {
540
541 wait_event_interruptible(lo->lo_event,
542 !bio_list_empty(&lo->lo_bio_list) ||
543 kthread_should_stop());
544
545 if (bio_list_empty(&lo->lo_bio_list))
546 continue;
547 spin_lock_irq(&lo->lo_lock);
548 bio = loop_get_bio(lo);
549 spin_unlock_irq(&lo->lo_lock);
550
551 BUG_ON(!bio);
552 loop_handle_bio(lo, bio);
553 }
554
555 return 0;
556}
557
558/*
559 * loop_switch performs the hard work of switching a backing store.
560 * First it needs to flush existing IO, it does this by sending a magic
561 * BIO down the pipe. The completion of this BIO does the actual switch.
562 */
563static int loop_switch(struct loop_device *lo, struct file *file)
564{
565 struct switch_request w;
566 struct bio *bio = bio_alloc(GFP_KERNEL, 0);
567 if (!bio)
568 return -ENOMEM;
569 init_completion(&w.wait);
570 w.file = file;
571 bio->bi_private = &w;
572 bio->bi_bdev = NULL;
573 loop_make_request(lo->lo_queue, bio);
574 wait_for_completion(&w.wait);
575 return 0;
576}
577
578/*
579 * Helper to flush the IOs in loop, but keeping loop thread running
580 */
581static int loop_flush(struct loop_device *lo)
582{
583 /* loop not yet configured, no running thread, nothing to flush */
584 if (!lo->lo_thread)
585 return 0;
586
587 return loop_switch(lo, NULL);
588}
589
590/*
591 * Do the actual switch; called from the BIO completion routine
592 */
593static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
594{
595 struct file *file = p->file;
596 struct file *old_file = lo->lo_backing_file;
597 struct address_space *mapping;
598
599 /* if no new file, only flush of queued bios requested */
600 if (!file)
601 goto out;
602
603 mapping = file->f_mapping;
604 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
605 lo->lo_backing_file = file;
606 lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
607 mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
608 lo->old_gfp_mask = mapping_gfp_mask(mapping);
609 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
610out:
611 complete(&p->wait);
612}
613
614
615/*
616 * loop_change_fd switched the backing store of a loopback device to
617 * a new file. This is useful for operating system installers to free up
618 * the original file and in High Availability environments to switch to
619 * an alternative location for the content in case of server meltdown.
620 * This can only work if the loop device is used read-only, and if the
621 * new backing store is the same size and type as the old backing store.
622 */
623static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
624 unsigned int arg)
625{
626 struct file *file, *old_file;
627 struct inode *inode;
628 int error;
629
630 error = -ENXIO;
631 if (lo->lo_state != Lo_bound)
632 goto out;
633
634 /* the loop device has to be read-only */
635 error = -EINVAL;
636 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
637 goto out;
638
639 error = -EBADF;
640 file = fget(arg);
641 if (!file)
642 goto out;
643
644 inode = file->f_mapping->host;
645 old_file = lo->lo_backing_file;
646
647 error = -EINVAL;
648
649 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
650 goto out_putf;
651
652 /* size of the new backing store needs to be the same */
653 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
654 goto out_putf;
655
656 /* and ... switch */
657 error = loop_switch(lo, file);
658 if (error)
659 goto out_putf;
660
661 fput(old_file);
662 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
663 ioctl_by_bdev(bdev, BLKRRPART, 0);
664 return 0;
665
666 out_putf:
667 fput(file);
668 out:
669 return error;
670}
671
672static inline int is_loop_device(struct file *file)
673{
674 struct inode *i = file->f_mapping->host;
675
676 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
677}
678
679/* loop sysfs attributes */
680
681static ssize_t loop_attr_show(struct device *dev, char *page,
682 ssize_t (*callback)(struct loop_device *, char *))
683{
684 struct gendisk *disk = dev_to_disk(dev);
685 struct loop_device *lo = disk->private_data;
686
687 return callback(lo, page);
688}
689
690#define LOOP_ATTR_RO(_name) \
691static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
692static ssize_t loop_attr_do_show_##_name(struct device *d, \
693 struct device_attribute *attr, char *b) \
694{ \
695 return loop_attr_show(d, b, loop_attr_##_name##_show); \
696} \
697static struct device_attribute loop_attr_##_name = \
698 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
699
700static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
701{
702 ssize_t ret;
703 char *p = NULL;
704
705 spin_lock_irq(&lo->lo_lock);
706 if (lo->lo_backing_file)
707 p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1);
708 spin_unlock_irq(&lo->lo_lock);
709
710 if (IS_ERR_OR_NULL(p))
711 ret = PTR_ERR(p);
712 else {
713 ret = strlen(p);
714 memmove(buf, p, ret);
715 buf[ret++] = '\n';
716 buf[ret] = 0;
717 }
718
719 return ret;
720}
721
722static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
723{
724 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
725}
726
727static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
728{
729 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
730}
731
732static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
733{
734 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
735
736 return sprintf(buf, "%s\n", autoclear ? "1" : "0");
737}
738
739static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
740{
741 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
742
743 return sprintf(buf, "%s\n", partscan ? "1" : "0");
744}
745
746LOOP_ATTR_RO(backing_file);
747LOOP_ATTR_RO(offset);
748LOOP_ATTR_RO(sizelimit);
749LOOP_ATTR_RO(autoclear);
750LOOP_ATTR_RO(partscan);
751
752static struct attribute *loop_attrs[] = {
753 &loop_attr_backing_file.attr,
754 &loop_attr_offset.attr,
755 &loop_attr_sizelimit.attr,
756 &loop_attr_autoclear.attr,
757 &loop_attr_partscan.attr,
758 NULL,
759};
760
761static struct attribute_group loop_attribute_group = {
762 .name = "loop",
763 .attrs= loop_attrs,
764};
765
766static int loop_sysfs_init(struct loop_device *lo)
767{
768 return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
769 &loop_attribute_group);
770}
771
772static void loop_sysfs_exit(struct loop_device *lo)
773{
774 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
775 &loop_attribute_group);
776}
777
778static void loop_config_discard(struct loop_device *lo)
779{
780 struct file *file = lo->lo_backing_file;
781 struct inode *inode = file->f_mapping->host;
782 struct request_queue *q = lo->lo_queue;
783
784 /*
785 * We use punch hole to reclaim the free space used by the
786 * image a.k.a. discard. However we do support discard if
787 * encryption is enabled, because it may give an attacker
788 * useful information.
789 */
790 if ((!file->f_op->fallocate) ||
791 lo->lo_encrypt_key_size) {
792 q->limits.discard_granularity = 0;
793 q->limits.discard_alignment = 0;
794 q->limits.max_discard_sectors = 0;
795 q->limits.discard_zeroes_data = 0;
796 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
797 return;
798 }
799
800 q->limits.discard_granularity = inode->i_sb->s_blocksize;
801 q->limits.discard_alignment = 0;
802 q->limits.max_discard_sectors = UINT_MAX >> 9;
803 q->limits.discard_zeroes_data = 1;
804 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
805}
806
807static int loop_set_fd(struct loop_device *lo, fmode_t mode,
808 struct block_device *bdev, unsigned int arg)
809{
810 struct file *file, *f;
811 struct inode *inode;
812 struct address_space *mapping;
813 unsigned lo_blocksize;
814 int lo_flags = 0;
815 int error;
816 loff_t size;
817
818 /* This is safe, since we have a reference from open(). */
819 __module_get(THIS_MODULE);
820
821 error = -EBADF;
822 file = fget(arg);
823 if (!file)
824 goto out;
825
826 error = -EBUSY;
827 if (lo->lo_state != Lo_unbound)
828 goto out_putf;
829
830 /* Avoid recursion */
831 f = file;
832 while (is_loop_device(f)) {
833 struct loop_device *l;
834
835 if (f->f_mapping->host->i_bdev == bdev)
836 goto out_putf;
837
838 l = f->f_mapping->host->i_bdev->bd_disk->private_data;
839 if (l->lo_state == Lo_unbound) {
840 error = -EINVAL;
841 goto out_putf;
842 }
843 f = l->lo_backing_file;
844 }
845
846 mapping = file->f_mapping;
847 inode = mapping->host;
848
849 error = -EINVAL;
850 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
851 goto out_putf;
852
853 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
854 !file->f_op->write)
855 lo_flags |= LO_FLAGS_READ_ONLY;
856
857 lo_blocksize = S_ISBLK(inode->i_mode) ?
858 inode->i_bdev->bd_block_size : PAGE_SIZE;
859
860 error = -EFBIG;
861 size = get_loop_size(lo, file);
862 if ((loff_t)(sector_t)size != size)
863 goto out_putf;
864
865 error = 0;
866
867 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
868
869 lo->lo_blocksize = lo_blocksize;
870 lo->lo_device = bdev;
871 lo->lo_flags = lo_flags;
872 lo->lo_backing_file = file;
873 lo->transfer = transfer_none;
874 lo->ioctl = NULL;
875 lo->lo_sizelimit = 0;
876 lo->old_gfp_mask = mapping_gfp_mask(mapping);
877 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
878
879 bio_list_init(&lo->lo_bio_list);
880
881 /*
882 * set queue make_request_fn, and add limits based on lower level
883 * device
884 */
885 blk_queue_make_request(lo->lo_queue, loop_make_request);
886 lo->lo_queue->queuedata = lo;
887
888 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
889 blk_queue_flush(lo->lo_queue, REQ_FLUSH);
890
891 set_capacity(lo->lo_disk, size);
892 bd_set_size(bdev, size << 9);
893 loop_sysfs_init(lo);
894 /* let user-space know about the new size */
895 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
896
897 set_blocksize(bdev, lo_blocksize);
898
899 lo->lo_thread = kthread_create(loop_thread, lo, "loop%d",
900 lo->lo_number);
901 if (IS_ERR(lo->lo_thread)) {
902 error = PTR_ERR(lo->lo_thread);
903 goto out_clr;
904 }
905 lo->lo_state = Lo_bound;
906 wake_up_process(lo->lo_thread);
907 if (part_shift)
908 lo->lo_flags |= LO_FLAGS_PARTSCAN;
909 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
910 ioctl_by_bdev(bdev, BLKRRPART, 0);
911 return 0;
912
913out_clr:
914 loop_sysfs_exit(lo);
915 lo->lo_thread = NULL;
916 lo->lo_device = NULL;
917 lo->lo_backing_file = NULL;
918 lo->lo_flags = 0;
919 set_capacity(lo->lo_disk, 0);
920 invalidate_bdev(bdev);
921 bd_set_size(bdev, 0);
922 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
923 mapping_set_gfp_mask(mapping, lo->old_gfp_mask);
924 lo->lo_state = Lo_unbound;
925 out_putf:
926 fput(file);
927 out:
928 /* This is safe: open() is still holding a reference. */
929 module_put(THIS_MODULE);
930 return error;
931}
932
933static int
934loop_release_xfer(struct loop_device *lo)
935{
936 int err = 0;
937 struct loop_func_table *xfer = lo->lo_encryption;
938
939 if (xfer) {
940 if (xfer->release)
941 err = xfer->release(lo);
942 lo->transfer = NULL;
943 lo->lo_encryption = NULL;
944 module_put(xfer->owner);
945 }
946 return err;
947}
948
949static int
950loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
951 const struct loop_info64 *i)
952{
953 int err = 0;
954
955 if (xfer) {
956 struct module *owner = xfer->owner;
957
958 if (!try_module_get(owner))
959 return -EINVAL;
960 if (xfer->init)
961 err = xfer->init(lo, i);
962 if (err)
963 module_put(owner);
964 else
965 lo->lo_encryption = xfer;
966 }
967 return err;
968}
969
970static int loop_clr_fd(struct loop_device *lo)
971{
972 struct file *filp = lo->lo_backing_file;
973 gfp_t gfp = lo->old_gfp_mask;
974 struct block_device *bdev = lo->lo_device;
975
976 if (lo->lo_state != Lo_bound)
977 return -ENXIO;
978
979 if (lo->lo_refcnt > 1) /* we needed one fd for the ioctl */
980 return -EBUSY;
981
982 if (filp == NULL)
983 return -EINVAL;
984
985 spin_lock_irq(&lo->lo_lock);
986 lo->lo_state = Lo_rundown;
987 spin_unlock_irq(&lo->lo_lock);
988
989 kthread_stop(lo->lo_thread);
990
991 spin_lock_irq(&lo->lo_lock);
992 lo->lo_backing_file = NULL;
993 spin_unlock_irq(&lo->lo_lock);
994
995 loop_release_xfer(lo);
996 lo->transfer = NULL;
997 lo->ioctl = NULL;
998 lo->lo_device = NULL;
999 lo->lo_encryption = NULL;
1000 lo->lo_offset = 0;
1001 lo->lo_sizelimit = 0;
1002 lo->lo_encrypt_key_size = 0;
1003 lo->lo_thread = NULL;
1004 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
1005 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
1006 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1007 if (bdev)
1008 invalidate_bdev(bdev);
1009 set_capacity(lo->lo_disk, 0);
1010 loop_sysfs_exit(lo);
1011 if (bdev) {
1012 bd_set_size(bdev, 0);
1013 /* let user-space know about this change */
1014 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1015 }
1016 mapping_set_gfp_mask(filp->f_mapping, gfp);
1017 lo->lo_state = Lo_unbound;
1018 /* This is safe: open() is still holding a reference. */
1019 module_put(THIS_MODULE);
1020 if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
1021 ioctl_by_bdev(bdev, BLKRRPART, 0);
1022 lo->lo_flags = 0;
1023 if (!part_shift)
1024 lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
1025 mutex_unlock(&lo->lo_ctl_mutex);
1026 /*
1027 * Need not hold lo_ctl_mutex to fput backing file.
1028 * Calling fput holding lo_ctl_mutex triggers a circular
1029 * lock dependency possibility warning as fput can take
1030 * bd_mutex which is usually taken before lo_ctl_mutex.
1031 */
1032 fput(filp);
1033 return 0;
1034}
1035
1036static int
1037loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1038{
1039 int err;
1040 struct loop_func_table *xfer;
1041 uid_t uid = current_uid();
1042
1043 if (lo->lo_encrypt_key_size &&
1044 lo->lo_key_owner != uid &&
1045 !capable(CAP_SYS_ADMIN))
1046 return -EPERM;
1047 if (lo->lo_state != Lo_bound)
1048 return -ENXIO;
1049 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
1050 return -EINVAL;
1051
1052 err = loop_release_xfer(lo);
1053 if (err)
1054 return err;
1055
1056 if (info->lo_encrypt_type) {
1057 unsigned int type = info->lo_encrypt_type;
1058
1059 if (type >= MAX_LO_CRYPT)
1060 return -EINVAL;
1061 xfer = xfer_funcs[type];
1062 if (xfer == NULL)
1063 return -EINVAL;
1064 } else
1065 xfer = NULL;
1066
1067 err = loop_init_xfer(lo, xfer, info);
1068 if (err)
1069 return err;
1070
1071 if (lo->lo_offset != info->lo_offset ||
1072 lo->lo_sizelimit != info->lo_sizelimit) {
1073 if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
1074 return -EFBIG;
1075 }
1076 loop_config_discard(lo);
1077
1078 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
1079 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
1080 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
1081 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
1082
1083 if (!xfer)
1084 xfer = &none_funcs;
1085 lo->transfer = xfer->transfer;
1086 lo->ioctl = xfer->ioctl;
1087
1088 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
1089 (info->lo_flags & LO_FLAGS_AUTOCLEAR))
1090 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
1091
1092 if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&
1093 !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
1094 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1095 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
1096 ioctl_by_bdev(lo->lo_device, BLKRRPART, 0);
1097 }
1098
1099 lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
1100 lo->lo_init[0] = info->lo_init[0];
1101 lo->lo_init[1] = info->lo_init[1];
1102 if (info->lo_encrypt_key_size) {
1103 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
1104 info->lo_encrypt_key_size);
1105 lo->lo_key_owner = uid;
1106 }
1107
1108 return 0;
1109}
1110
1111static int
1112loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1113{
1114 struct file *file = lo->lo_backing_file;
1115 struct kstat stat;
1116 int error;
1117
1118 if (lo->lo_state != Lo_bound)
1119 return -ENXIO;
1120 error = vfs_getattr(file->f_path.mnt, file->f_path.dentry, &stat);
1121 if (error)
1122 return error;
1123 memset(info, 0, sizeof(*info));
1124 info->lo_number = lo->lo_number;
1125 info->lo_device = huge_encode_dev(stat.dev);
1126 info->lo_inode = stat.ino;
1127 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
1128 info->lo_offset = lo->lo_offset;
1129 info->lo_sizelimit = lo->lo_sizelimit;
1130 info->lo_flags = lo->lo_flags;
1131 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1132 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1133 info->lo_encrypt_type =
1134 lo->lo_encryption ? lo->lo_encryption->number : 0;
1135 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1136 info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1137 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1138 lo->lo_encrypt_key_size);
1139 }
1140 return 0;
1141}
1142
1143static void
1144loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1145{
1146 memset(info64, 0, sizeof(*info64));
1147 info64->lo_number = info->lo_number;
1148 info64->lo_device = info->lo_device;
1149 info64->lo_inode = info->lo_inode;
1150 info64->lo_rdevice = info->lo_rdevice;
1151 info64->lo_offset = info->lo_offset;
1152 info64->lo_sizelimit = 0;
1153 info64->lo_encrypt_type = info->lo_encrypt_type;
1154 info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1155 info64->lo_flags = info->lo_flags;
1156 info64->lo_init[0] = info->lo_init[0];
1157 info64->lo_init[1] = info->lo_init[1];
1158 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1159 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1160 else
1161 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1162 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1163}
1164
1165static int
1166loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1167{
1168 memset(info, 0, sizeof(*info));
1169 info->lo_number = info64->lo_number;
1170 info->lo_device = info64->lo_device;
1171 info->lo_inode = info64->lo_inode;
1172 info->lo_rdevice = info64->lo_rdevice;
1173 info->lo_offset = info64->lo_offset;
1174 info->lo_encrypt_type = info64->lo_encrypt_type;
1175 info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1176 info->lo_flags = info64->lo_flags;
1177 info->lo_init[0] = info64->lo_init[0];
1178 info->lo_init[1] = info64->lo_init[1];
1179 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1180 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1181 else
1182 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1183 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1184
1185 /* error in case values were truncated */
1186 if (info->lo_device != info64->lo_device ||
1187 info->lo_rdevice != info64->lo_rdevice ||
1188 info->lo_inode != info64->lo_inode ||
1189 info->lo_offset != info64->lo_offset)
1190 return -EOVERFLOW;
1191
1192 return 0;
1193}
1194
1195static int
1196loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1197{
1198 struct loop_info info;
1199 struct loop_info64 info64;
1200
1201 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1202 return -EFAULT;
1203 loop_info64_from_old(&info, &info64);
1204 return loop_set_status(lo, &info64);
1205}
1206
1207static int
1208loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1209{
1210 struct loop_info64 info64;
1211
1212 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1213 return -EFAULT;
1214 return loop_set_status(lo, &info64);
1215}
1216
1217static int
1218loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1219 struct loop_info info;
1220 struct loop_info64 info64;
1221 int err = 0;
1222
1223 if (!arg)
1224 err = -EINVAL;
1225 if (!err)
1226 err = loop_get_status(lo, &info64);
1227 if (!err)
1228 err = loop_info64_to_old(&info64, &info);
1229 if (!err && copy_to_user(arg, &info, sizeof(info)))
1230 err = -EFAULT;
1231
1232 return err;
1233}
1234
1235static int
1236loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1237 struct loop_info64 info64;
1238 int err = 0;
1239
1240 if (!arg)
1241 err = -EINVAL;
1242 if (!err)
1243 err = loop_get_status(lo, &info64);
1244 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1245 err = -EFAULT;
1246
1247 return err;
1248}
1249
1250static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
1251{
1252 int err;
1253 sector_t sec;
1254 loff_t sz;
1255
1256 err = -ENXIO;
1257 if (unlikely(lo->lo_state != Lo_bound))
1258 goto out;
1259 err = figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
1260 if (unlikely(err))
1261 goto out;
1262 sec = get_capacity(lo->lo_disk);
1263 /* the width of sector_t may be narrow for bit-shift */
1264 sz = sec;
1265 sz <<= 9;
1266 mutex_lock(&bdev->bd_mutex);
1267 bd_set_size(bdev, sz);
1268 /* let user-space know about the new size */
1269 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1270 mutex_unlock(&bdev->bd_mutex);
1271
1272 out:
1273 return err;
1274}
1275
1276static int lo_ioctl(struct block_device *bdev, fmode_t mode,
1277 unsigned int cmd, unsigned long arg)
1278{
1279 struct loop_device *lo = bdev->bd_disk->private_data;
1280 int err;
1281
1282 mutex_lock_nested(&lo->lo_ctl_mutex, 1);
1283 switch (cmd) {
1284 case LOOP_SET_FD:
1285 err = loop_set_fd(lo, mode, bdev, arg);
1286 break;
1287 case LOOP_CHANGE_FD:
1288 err = loop_change_fd(lo, bdev, arg);
1289 break;
1290 case LOOP_CLR_FD:
1291 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1292 err = loop_clr_fd(lo);
1293 if (!err)
1294 goto out_unlocked;
1295 break;
1296 case LOOP_SET_STATUS:
1297 err = -EPERM;
1298 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1299 err = loop_set_status_old(lo,
1300 (struct loop_info __user *)arg);
1301 break;
1302 case LOOP_GET_STATUS:
1303 err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1304 break;
1305 case LOOP_SET_STATUS64:
1306 err = -EPERM;
1307 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1308 err = loop_set_status64(lo,
1309 (struct loop_info64 __user *) arg);
1310 break;
1311 case LOOP_GET_STATUS64:
1312 err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1313 break;
1314 case LOOP_SET_CAPACITY:
1315 err = -EPERM;
1316 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1317 err = loop_set_capacity(lo, bdev);
1318 break;
1319 default:
1320 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1321 }
1322 mutex_unlock(&lo->lo_ctl_mutex);
1323
1324out_unlocked:
1325 return err;
1326}
1327
1328#ifdef CONFIG_COMPAT
1329struct compat_loop_info {
1330 compat_int_t lo_number; /* ioctl r/o */
1331 compat_dev_t lo_device; /* ioctl r/o */
1332 compat_ulong_t lo_inode; /* ioctl r/o */
1333 compat_dev_t lo_rdevice; /* ioctl r/o */
1334 compat_int_t lo_offset;
1335 compat_int_t lo_encrypt_type;
1336 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1337 compat_int_t lo_flags; /* ioctl r/o */
1338 char lo_name[LO_NAME_SIZE];
1339 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1340 compat_ulong_t lo_init[2];
1341 char reserved[4];
1342};
1343
1344/*
1345 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1346 * - noinlined to reduce stack space usage in main part of driver
1347 */
1348static noinline int
1349loop_info64_from_compat(const struct compat_loop_info __user *arg,
1350 struct loop_info64 *info64)
1351{
1352 struct compat_loop_info info;
1353
1354 if (copy_from_user(&info, arg, sizeof(info)))
1355 return -EFAULT;
1356
1357 memset(info64, 0, sizeof(*info64));
1358 info64->lo_number = info.lo_number;
1359 info64->lo_device = info.lo_device;
1360 info64->lo_inode = info.lo_inode;
1361 info64->lo_rdevice = info.lo_rdevice;
1362 info64->lo_offset = info.lo_offset;
1363 info64->lo_sizelimit = 0;
1364 info64->lo_encrypt_type = info.lo_encrypt_type;
1365 info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1366 info64->lo_flags = info.lo_flags;
1367 info64->lo_init[0] = info.lo_init[0];
1368 info64->lo_init[1] = info.lo_init[1];
1369 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1370 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1371 else
1372 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1373 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1374 return 0;
1375}
1376
1377/*
1378 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1379 * - noinlined to reduce stack space usage in main part of driver
1380 */
1381static noinline int
1382loop_info64_to_compat(const struct loop_info64 *info64,
1383 struct compat_loop_info __user *arg)
1384{
1385 struct compat_loop_info info;
1386
1387 memset(&info, 0, sizeof(info));
1388 info.lo_number = info64->lo_number;
1389 info.lo_device = info64->lo_device;
1390 info.lo_inode = info64->lo_inode;
1391 info.lo_rdevice = info64->lo_rdevice;
1392 info.lo_offset = info64->lo_offset;
1393 info.lo_encrypt_type = info64->lo_encrypt_type;
1394 info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
1395 info.lo_flags = info64->lo_flags;
1396 info.lo_init[0] = info64->lo_init[0];
1397 info.lo_init[1] = info64->lo_init[1];
1398 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1399 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1400 else
1401 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1402 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1403
1404 /* error in case values were truncated */
1405 if (info.lo_device != info64->lo_device ||
1406 info.lo_rdevice != info64->lo_rdevice ||
1407 info.lo_inode != info64->lo_inode ||
1408 info.lo_offset != info64->lo_offset ||
1409 info.lo_init[0] != info64->lo_init[0] ||
1410 info.lo_init[1] != info64->lo_init[1])
1411 return -EOVERFLOW;
1412
1413 if (copy_to_user(arg, &info, sizeof(info)))
1414 return -EFAULT;
1415 return 0;
1416}
1417
1418static int
1419loop_set_status_compat(struct loop_device *lo,
1420 const struct compat_loop_info __user *arg)
1421{
1422 struct loop_info64 info64;
1423 int ret;
1424
1425 ret = loop_info64_from_compat(arg, &info64);
1426 if (ret < 0)
1427 return ret;
1428 return loop_set_status(lo, &info64);
1429}
1430
1431static int
1432loop_get_status_compat(struct loop_device *lo,
1433 struct compat_loop_info __user *arg)
1434{
1435 struct loop_info64 info64;
1436 int err = 0;
1437
1438 if (!arg)
1439 err = -EINVAL;
1440 if (!err)
1441 err = loop_get_status(lo, &info64);
1442 if (!err)
1443 err = loop_info64_to_compat(&info64, arg);
1444 return err;
1445}
1446
1447static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1448 unsigned int cmd, unsigned long arg)
1449{
1450 struct loop_device *lo = bdev->bd_disk->private_data;
1451 int err;
1452
1453 switch(cmd) {
1454 case LOOP_SET_STATUS:
1455 mutex_lock(&lo->lo_ctl_mutex);
1456 err = loop_set_status_compat(
1457 lo, (const struct compat_loop_info __user *) arg);
1458 mutex_unlock(&lo->lo_ctl_mutex);
1459 break;
1460 case LOOP_GET_STATUS:
1461 mutex_lock(&lo->lo_ctl_mutex);
1462 err = loop_get_status_compat(
1463 lo, (struct compat_loop_info __user *) arg);
1464 mutex_unlock(&lo->lo_ctl_mutex);
1465 break;
1466 case LOOP_SET_CAPACITY:
1467 case LOOP_CLR_FD:
1468 case LOOP_GET_STATUS64:
1469 case LOOP_SET_STATUS64:
1470 arg = (unsigned long) compat_ptr(arg);
1471 case LOOP_SET_FD:
1472 case LOOP_CHANGE_FD:
1473 err = lo_ioctl(bdev, mode, cmd, arg);
1474 break;
1475 default:
1476 err = -ENOIOCTLCMD;
1477 break;
1478 }
1479 return err;
1480}
1481#endif
1482
1483static int lo_open(struct block_device *bdev, fmode_t mode)
1484{
1485 struct loop_device *lo;
1486 int err = 0;
1487
1488 mutex_lock(&loop_index_mutex);
1489 lo = bdev->bd_disk->private_data;
1490 if (!lo) {
1491 err = -ENXIO;
1492 goto out;
1493 }
1494
1495 mutex_lock(&lo->lo_ctl_mutex);
1496 lo->lo_refcnt++;
1497 mutex_unlock(&lo->lo_ctl_mutex);
1498out:
1499 mutex_unlock(&loop_index_mutex);
1500 return err;
1501}
1502
1503static int lo_release(struct gendisk *disk, fmode_t mode)
1504{
1505 struct loop_device *lo = disk->private_data;
1506 int err;
1507
1508 mutex_lock(&lo->lo_ctl_mutex);
1509
1510 if (--lo->lo_refcnt)
1511 goto out;
1512
1513 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
1514 /*
1515 * In autoclear mode, stop the loop thread
1516 * and remove configuration after last close.
1517 */
1518 err = loop_clr_fd(lo);
1519 if (!err)
1520 goto out_unlocked;
1521 } else {
1522 /*
1523 * Otherwise keep thread (if running) and config,
1524 * but flush possible ongoing bios in thread.
1525 */
1526 loop_flush(lo);
1527 }
1528
1529out:
1530 mutex_unlock(&lo->lo_ctl_mutex);
1531out_unlocked:
1532 return 0;
1533}
1534
1535static const struct block_device_operations lo_fops = {
1536 .owner = THIS_MODULE,
1537 .open = lo_open,
1538 .release = lo_release,
1539 .ioctl = lo_ioctl,
1540#ifdef CONFIG_COMPAT
1541 .compat_ioctl = lo_compat_ioctl,
1542#endif
1543};
1544
1545/*
1546 * And now the modules code and kernel interface.
1547 */
1548static int max_loop;
1549module_param(max_loop, int, S_IRUGO);
1550MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1551module_param(max_part, int, S_IRUGO);
1552MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1553MODULE_LICENSE("GPL");
1554MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1555
1556int loop_register_transfer(struct loop_func_table *funcs)
1557{
1558 unsigned int n = funcs->number;
1559
1560 if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1561 return -EINVAL;
1562 xfer_funcs[n] = funcs;
1563 return 0;
1564}
1565
1566static int unregister_transfer_cb(int id, void *ptr, void *data)
1567{
1568 struct loop_device *lo = ptr;
1569 struct loop_func_table *xfer = data;
1570
1571 mutex_lock(&lo->lo_ctl_mutex);
1572 if (lo->lo_encryption == xfer)
1573 loop_release_xfer(lo);
1574 mutex_unlock(&lo->lo_ctl_mutex);
1575 return 0;
1576}
1577
1578int loop_unregister_transfer(int number)
1579{
1580 unsigned int n = number;
1581 struct loop_func_table *xfer;
1582
1583 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1584 return -EINVAL;
1585
1586 xfer_funcs[n] = NULL;
1587 idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
1588 return 0;
1589}
1590
1591EXPORT_SYMBOL(loop_register_transfer);
1592EXPORT_SYMBOL(loop_unregister_transfer);
1593
1594static int loop_add(struct loop_device **l, int i)
1595{
1596 struct loop_device *lo;
1597 struct gendisk *disk;
1598 int err;
1599
1600 err = -ENOMEM;
1601 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1602 if (!lo)
1603 goto out;
1604
1605 if (!idr_pre_get(&loop_index_idr, GFP_KERNEL))
1606 goto out_free_dev;
1607
1608 if (i >= 0) {
1609 int m;
1610
1611 /* create specific i in the index */
1612 err = idr_get_new_above(&loop_index_idr, lo, i, &m);
1613 if (err >= 0 && i != m) {
1614 idr_remove(&loop_index_idr, m);
1615 err = -EEXIST;
1616 }
1617 } else if (i == -1) {
1618 int m;
1619
1620 /* get next free nr */
1621 err = idr_get_new(&loop_index_idr, lo, &m);
1622 if (err >= 0)
1623 i = m;
1624 } else {
1625 err = -EINVAL;
1626 }
1627 if (err < 0)
1628 goto out_free_dev;
1629
1630 lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
1631 if (!lo->lo_queue)
1632 goto out_free_dev;
1633
1634 disk = lo->lo_disk = alloc_disk(1 << part_shift);
1635 if (!disk)
1636 goto out_free_queue;
1637
1638 /*
1639 * Disable partition scanning by default. The in-kernel partition
1640 * scanning can be requested individually per-device during its
1641 * setup. Userspace can always add and remove partitions from all
1642 * devices. The needed partition minors are allocated from the
1643 * extended minor space, the main loop device numbers will continue
1644 * to match the loop minors, regardless of the number of partitions
1645 * used.
1646 *
1647 * If max_part is given, partition scanning is globally enabled for
1648 * all loop devices. The minors for the main loop devices will be
1649 * multiples of max_part.
1650 *
1651 * Note: Global-for-all-devices, set-only-at-init, read-only module
1652 * parameteters like 'max_loop' and 'max_part' make things needlessly
1653 * complicated, are too static, inflexible and may surprise
1654 * userspace tools. Parameters like this in general should be avoided.
1655 */
1656 if (!part_shift)
1657 disk->flags |= GENHD_FL_NO_PART_SCAN;
1658 disk->flags |= GENHD_FL_EXT_DEVT;
1659 mutex_init(&lo->lo_ctl_mutex);
1660 lo->lo_number = i;
1661 lo->lo_thread = NULL;
1662 init_waitqueue_head(&lo->lo_event);
1663 spin_lock_init(&lo->lo_lock);
1664 disk->major = LOOP_MAJOR;
1665 disk->first_minor = i << part_shift;
1666 disk->fops = &lo_fops;
1667 disk->private_data = lo;
1668 disk->queue = lo->lo_queue;
1669 sprintf(disk->disk_name, "loop%d", i);
1670 add_disk(disk);
1671 *l = lo;
1672 return lo->lo_number;
1673
1674out_free_queue:
1675 blk_cleanup_queue(lo->lo_queue);
1676out_free_dev:
1677 kfree(lo);
1678out:
1679 return err;
1680}
1681
1682static void loop_remove(struct loop_device *lo)
1683{
1684 del_gendisk(lo->lo_disk);
1685 blk_cleanup_queue(lo->lo_queue);
1686 put_disk(lo->lo_disk);
1687 kfree(lo);
1688}
1689
1690static int find_free_cb(int id, void *ptr, void *data)
1691{
1692 struct loop_device *lo = ptr;
1693 struct loop_device **l = data;
1694
1695 if (lo->lo_state == Lo_unbound) {
1696 *l = lo;
1697 return 1;
1698 }
1699 return 0;
1700}
1701
1702static int loop_lookup(struct loop_device **l, int i)
1703{
1704 struct loop_device *lo;
1705 int ret = -ENODEV;
1706
1707 if (i < 0) {
1708 int err;
1709
1710 err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
1711 if (err == 1) {
1712 *l = lo;
1713 ret = lo->lo_number;
1714 }
1715 goto out;
1716 }
1717
1718 /* lookup and return a specific i */
1719 lo = idr_find(&loop_index_idr, i);
1720 if (lo) {
1721 *l = lo;
1722 ret = lo->lo_number;
1723 }
1724out:
1725 return ret;
1726}
1727
1728static struct kobject *loop_probe(dev_t dev, int *part, void *data)
1729{
1730 struct loop_device *lo;
1731 struct kobject *kobj;
1732 int err;
1733
1734 mutex_lock(&loop_index_mutex);
1735 err = loop_lookup(&lo, MINOR(dev) >> part_shift);
1736 if (err < 0)
1737 err = loop_add(&lo, MINOR(dev) >> part_shift);
1738 if (err < 0)
1739 kobj = ERR_PTR(err);
1740 else
1741 kobj = get_disk(lo->lo_disk);
1742 mutex_unlock(&loop_index_mutex);
1743
1744 *part = 0;
1745 return kobj;
1746}
1747
1748static long loop_control_ioctl(struct file *file, unsigned int cmd,
1749 unsigned long parm)
1750{
1751 struct loop_device *lo;
1752 int ret = -ENOSYS;
1753
1754 mutex_lock(&loop_index_mutex);
1755 switch (cmd) {
1756 case LOOP_CTL_ADD:
1757 ret = loop_lookup(&lo, parm);
1758 if (ret >= 0) {
1759 ret = -EEXIST;
1760 break;
1761 }
1762 ret = loop_add(&lo, parm);
1763 break;
1764 case LOOP_CTL_REMOVE:
1765 ret = loop_lookup(&lo, parm);
1766 if (ret < 0)
1767 break;
1768 mutex_lock(&lo->lo_ctl_mutex);
1769 if (lo->lo_state != Lo_unbound) {
1770 ret = -EBUSY;
1771 mutex_unlock(&lo->lo_ctl_mutex);
1772 break;
1773 }
1774 if (lo->lo_refcnt > 0) {
1775 ret = -EBUSY;
1776 mutex_unlock(&lo->lo_ctl_mutex);
1777 break;
1778 }
1779 lo->lo_disk->private_data = NULL;
1780 mutex_unlock(&lo->lo_ctl_mutex);
1781 idr_remove(&loop_index_idr, lo->lo_number);
1782 loop_remove(lo);
1783 break;
1784 case LOOP_CTL_GET_FREE:
1785 ret = loop_lookup(&lo, -1);
1786 if (ret >= 0)
1787 break;
1788 ret = loop_add(&lo, -1);
1789 }
1790 mutex_unlock(&loop_index_mutex);
1791
1792 return ret;
1793}
1794
1795static const struct file_operations loop_ctl_fops = {
1796 .open = nonseekable_open,
1797 .unlocked_ioctl = loop_control_ioctl,
1798 .compat_ioctl = loop_control_ioctl,
1799 .owner = THIS_MODULE,
1800 .llseek = noop_llseek,
1801};
1802
1803static struct miscdevice loop_misc = {
1804 .minor = LOOP_CTRL_MINOR,
1805 .name = "loop-control",
1806 .fops = &loop_ctl_fops,
1807};
1808
1809MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
1810MODULE_ALIAS("devname:loop-control");
1811
1812static int __init loop_init(void)
1813{
1814 int i, nr;
1815 unsigned long range;
1816 struct loop_device *lo;
1817 int err;
1818
1819 err = misc_register(&loop_misc);
1820 if (err < 0)
1821 return err;
1822
1823 part_shift = 0;
1824 if (max_part > 0) {
1825 part_shift = fls(max_part);
1826
1827 /*
1828 * Adjust max_part according to part_shift as it is exported
1829 * to user space so that user can decide correct minor number
1830 * if [s]he want to create more devices.
1831 *
1832 * Note that -1 is required because partition 0 is reserved
1833 * for the whole disk.
1834 */
1835 max_part = (1UL << part_shift) - 1;
1836 }
1837
1838 if ((1UL << part_shift) > DISK_MAX_PARTS)
1839 return -EINVAL;
1840
1841 if (max_loop > 1UL << (MINORBITS - part_shift))
1842 return -EINVAL;
1843
1844 /*
1845 * If max_loop is specified, create that many devices upfront.
1846 * This also becomes a hard limit. If max_loop is not specified,
1847 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1848 * init time. Loop devices can be requested on-demand with the
1849 * /dev/loop-control interface, or be instantiated by accessing
1850 * a 'dead' device node.
1851 */
1852 if (max_loop) {
1853 nr = max_loop;
1854 range = max_loop << part_shift;
1855 } else {
1856 nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1857 range = 1UL << MINORBITS;
1858 }
1859
1860 if (register_blkdev(LOOP_MAJOR, "loop"))
1861 return -EIO;
1862
1863 blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
1864 THIS_MODULE, loop_probe, NULL, NULL);
1865
1866 /* pre-create number of devices given by config or max_loop */
1867 mutex_lock(&loop_index_mutex);
1868 for (i = 0; i < nr; i++)
1869 loop_add(&lo, i);
1870 mutex_unlock(&loop_index_mutex);
1871
1872 printk(KERN_INFO "loop: module loaded\n");
1873 return 0;
1874}
1875
1876static int loop_exit_cb(int id, void *ptr, void *data)
1877{
1878 struct loop_device *lo = ptr;
1879
1880 loop_remove(lo);
1881 return 0;
1882}
1883
1884static void __exit loop_exit(void)
1885{
1886 unsigned long range;
1887
1888 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
1889
1890 idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
1891 idr_remove_all(&loop_index_idr);
1892 idr_destroy(&loop_index_idr);
1893
1894 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
1895 unregister_blkdev(LOOP_MAJOR, "loop");
1896
1897 misc_deregister(&loop_misc);
1898}
1899
1900module_init(loop_init);
1901module_exit(loop_exit);
1902
1903#ifndef MODULE
1904static int __init max_loop_setup(char *str)
1905{
1906 max_loop = simple_strtol(str, NULL, 0);
1907 return 1;
1908}
1909
1910__setup("max_loop=", max_loop_setup);
1911#endif
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright 1993 by Theodore Ts'o.
4 */
5#include <linux/module.h>
6#include <linux/moduleparam.h>
7#include <linux/sched.h>
8#include <linux/fs.h>
9#include <linux/pagemap.h>
10#include <linux/file.h>
11#include <linux/stat.h>
12#include <linux/errno.h>
13#include <linux/major.h>
14#include <linux/wait.h>
15#include <linux/blkpg.h>
16#include <linux/init.h>
17#include <linux/swap.h>
18#include <linux/slab.h>
19#include <linux/compat.h>
20#include <linux/suspend.h>
21#include <linux/freezer.h>
22#include <linux/mutex.h>
23#include <linux/writeback.h>
24#include <linux/completion.h>
25#include <linux/highmem.h>
26#include <linux/splice.h>
27#include <linux/sysfs.h>
28#include <linux/miscdevice.h>
29#include <linux/falloc.h>
30#include <linux/uio.h>
31#include <linux/ioprio.h>
32#include <linux/blk-cgroup.h>
33#include <linux/sched/mm.h>
34#include <linux/statfs.h>
35#include <linux/uaccess.h>
36#include <linux/blk-mq.h>
37#include <linux/spinlock.h>
38#include <uapi/linux/loop.h>
39
40/* Possible states of device */
41enum {
42 Lo_unbound,
43 Lo_bound,
44 Lo_rundown,
45 Lo_deleting,
46};
47
48struct loop_func_table;
49
50struct loop_device {
51 int lo_number;
52 loff_t lo_offset;
53 loff_t lo_sizelimit;
54 int lo_flags;
55 char lo_file_name[LO_NAME_SIZE];
56
57 struct file * lo_backing_file;
58 struct block_device *lo_device;
59
60 gfp_t old_gfp_mask;
61
62 spinlock_t lo_lock;
63 int lo_state;
64 spinlock_t lo_work_lock;
65 struct workqueue_struct *workqueue;
66 struct work_struct rootcg_work;
67 struct list_head rootcg_cmd_list;
68 struct list_head idle_worker_list;
69 struct rb_root worker_tree;
70 struct timer_list timer;
71 bool use_dio;
72 bool sysfs_inited;
73
74 struct request_queue *lo_queue;
75 struct blk_mq_tag_set tag_set;
76 struct gendisk *lo_disk;
77 struct mutex lo_mutex;
78 bool idr_visible;
79};
80
81struct loop_cmd {
82 struct list_head list_entry;
83 bool use_aio; /* use AIO interface to handle I/O */
84 atomic_t ref; /* only for aio */
85 long ret;
86 struct kiocb iocb;
87 struct bio_vec *bvec;
88 struct cgroup_subsys_state *blkcg_css;
89 struct cgroup_subsys_state *memcg_css;
90};
91
92#define LOOP_IDLE_WORKER_TIMEOUT (60 * HZ)
93#define LOOP_DEFAULT_HW_Q_DEPTH (128)
94
95static DEFINE_IDR(loop_index_idr);
96static DEFINE_MUTEX(loop_ctl_mutex);
97static DEFINE_MUTEX(loop_validate_mutex);
98
99/**
100 * loop_global_lock_killable() - take locks for safe loop_validate_file() test
101 *
102 * @lo: struct loop_device
103 * @global: true if @lo is about to bind another "struct loop_device", false otherwise
104 *
105 * Returns 0 on success, -EINTR otherwise.
106 *
107 * Since loop_validate_file() traverses on other "struct loop_device" if
108 * is_loop_device() is true, we need a global lock for serializing concurrent
109 * loop_configure()/loop_change_fd()/__loop_clr_fd() calls.
110 */
111static int loop_global_lock_killable(struct loop_device *lo, bool global)
112{
113 int err;
114
115 if (global) {
116 err = mutex_lock_killable(&loop_validate_mutex);
117 if (err)
118 return err;
119 }
120 err = mutex_lock_killable(&lo->lo_mutex);
121 if (err && global)
122 mutex_unlock(&loop_validate_mutex);
123 return err;
124}
125
126/**
127 * loop_global_unlock() - release locks taken by loop_global_lock_killable()
128 *
129 * @lo: struct loop_device
130 * @global: true if @lo was about to bind another "struct loop_device", false otherwise
131 */
132static void loop_global_unlock(struct loop_device *lo, bool global)
133{
134 mutex_unlock(&lo->lo_mutex);
135 if (global)
136 mutex_unlock(&loop_validate_mutex);
137}
138
139static int max_part;
140static int part_shift;
141
142static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
143{
144 loff_t loopsize;
145
146 /* Compute loopsize in bytes */
147 loopsize = i_size_read(file->f_mapping->host);
148 if (offset > 0)
149 loopsize -= offset;
150 /* offset is beyond i_size, weird but possible */
151 if (loopsize < 0)
152 return 0;
153
154 if (sizelimit > 0 && sizelimit < loopsize)
155 loopsize = sizelimit;
156 /*
157 * Unfortunately, if we want to do I/O on the device,
158 * the number of 512-byte sectors has to fit into a sector_t.
159 */
160 return loopsize >> 9;
161}
162
163static loff_t get_loop_size(struct loop_device *lo, struct file *file)
164{
165 return get_size(lo->lo_offset, lo->lo_sizelimit, file);
166}
167
168static void __loop_update_dio(struct loop_device *lo, bool dio)
169{
170 struct file *file = lo->lo_backing_file;
171 struct address_space *mapping = file->f_mapping;
172 struct inode *inode = mapping->host;
173 unsigned short sb_bsize = 0;
174 unsigned dio_align = 0;
175 bool use_dio;
176
177 if (inode->i_sb->s_bdev) {
178 sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
179 dio_align = sb_bsize - 1;
180 }
181
182 /*
183 * We support direct I/O only if lo_offset is aligned with the
184 * logical I/O size of backing device, and the logical block
185 * size of loop is bigger than the backing device's.
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 applications should be PAGE_SIZE aligned
190 */
191 if (dio) {
192 if (queue_logical_block_size(lo->lo_queue) >= sb_bsize &&
193 !(lo->lo_offset & dio_align) &&
194 (file->f_mode & FMODE_CAN_ODIRECT))
195 use_dio = true;
196 else
197 use_dio = false;
198 } else {
199 use_dio = false;
200 }
201
202 if (lo->use_dio == use_dio)
203 return;
204
205 /* flush dirty pages before changing direct IO */
206 vfs_fsync(file, 0);
207
208 /*
209 * The flag of LO_FLAGS_DIRECT_IO is handled similarly with
210 * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup
211 * will get updated by ioctl(LOOP_GET_STATUS)
212 */
213 if (lo->lo_state == Lo_bound)
214 blk_mq_freeze_queue(lo->lo_queue);
215 lo->use_dio = use_dio;
216 if (use_dio) {
217 blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, lo->lo_queue);
218 lo->lo_flags |= LO_FLAGS_DIRECT_IO;
219 } else {
220 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
221 lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
222 }
223 if (lo->lo_state == Lo_bound)
224 blk_mq_unfreeze_queue(lo->lo_queue);
225}
226
227/**
228 * loop_set_size() - sets device size and notifies userspace
229 * @lo: struct loop_device to set the size for
230 * @size: new size of the loop device
231 *
232 * Callers must validate that the size passed into this function fits into
233 * a sector_t, eg using loop_validate_size()
234 */
235static void loop_set_size(struct loop_device *lo, loff_t size)
236{
237 if (!set_capacity_and_notify(lo->lo_disk, size))
238 kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
239}
240
241static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)
242{
243 struct iov_iter i;
244 ssize_t bw;
245
246 iov_iter_bvec(&i, ITER_SOURCE, bvec, 1, bvec->bv_len);
247
248 file_start_write(file);
249 bw = vfs_iter_write(file, &i, ppos, 0);
250 file_end_write(file);
251
252 if (likely(bw == bvec->bv_len))
253 return 0;
254
255 printk_ratelimited(KERN_ERR
256 "loop: Write error at byte offset %llu, length %i.\n",
257 (unsigned long long)*ppos, bvec->bv_len);
258 if (bw >= 0)
259 bw = -EIO;
260 return bw;
261}
262
263static int lo_write_simple(struct loop_device *lo, struct request *rq,
264 loff_t pos)
265{
266 struct bio_vec bvec;
267 struct req_iterator iter;
268 int ret = 0;
269
270 rq_for_each_segment(bvec, rq, iter) {
271 ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
272 if (ret < 0)
273 break;
274 cond_resched();
275 }
276
277 return ret;
278}
279
280static int lo_read_simple(struct loop_device *lo, struct request *rq,
281 loff_t pos)
282{
283 struct bio_vec bvec;
284 struct req_iterator iter;
285 struct iov_iter i;
286 ssize_t len;
287
288 rq_for_each_segment(bvec, rq, iter) {
289 iov_iter_bvec(&i, ITER_DEST, &bvec, 1, bvec.bv_len);
290 len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);
291 if (len < 0)
292 return len;
293
294 flush_dcache_page(bvec.bv_page);
295
296 if (len != bvec.bv_len) {
297 struct bio *bio;
298
299 __rq_for_each_bio(bio, rq)
300 zero_fill_bio(bio);
301 break;
302 }
303 cond_resched();
304 }
305
306 return 0;
307}
308
309static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos,
310 int mode)
311{
312 /*
313 * We use fallocate to manipulate the space mappings used by the image
314 * a.k.a. discard/zerorange.
315 */
316 struct file *file = lo->lo_backing_file;
317 int ret;
318
319 mode |= FALLOC_FL_KEEP_SIZE;
320
321 if (!bdev_max_discard_sectors(lo->lo_device))
322 return -EOPNOTSUPP;
323
324 ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
325 if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
326 return -EIO;
327 return ret;
328}
329
330static int lo_req_flush(struct loop_device *lo, struct request *rq)
331{
332 int ret = vfs_fsync(lo->lo_backing_file, 0);
333 if (unlikely(ret && ret != -EINVAL))
334 ret = -EIO;
335
336 return ret;
337}
338
339static void lo_complete_rq(struct request *rq)
340{
341 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
342 blk_status_t ret = BLK_STS_OK;
343
344 if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) ||
345 req_op(rq) != REQ_OP_READ) {
346 if (cmd->ret < 0)
347 ret = errno_to_blk_status(cmd->ret);
348 goto end_io;
349 }
350
351 /*
352 * Short READ - if we got some data, advance our request and
353 * retry it. If we got no data, end the rest with EIO.
354 */
355 if (cmd->ret) {
356 blk_update_request(rq, BLK_STS_OK, cmd->ret);
357 cmd->ret = 0;
358 blk_mq_requeue_request(rq, true);
359 } else {
360 if (cmd->use_aio) {
361 struct bio *bio = rq->bio;
362
363 while (bio) {
364 zero_fill_bio(bio);
365 bio = bio->bi_next;
366 }
367 }
368 ret = BLK_STS_IOERR;
369end_io:
370 blk_mq_end_request(rq, ret);
371 }
372}
373
374static void lo_rw_aio_do_completion(struct loop_cmd *cmd)
375{
376 struct request *rq = blk_mq_rq_from_pdu(cmd);
377
378 if (!atomic_dec_and_test(&cmd->ref))
379 return;
380 kfree(cmd->bvec);
381 cmd->bvec = NULL;
382 if (likely(!blk_should_fake_timeout(rq->q)))
383 blk_mq_complete_request(rq);
384}
385
386static void lo_rw_aio_complete(struct kiocb *iocb, long ret)
387{
388 struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb);
389
390 cmd->ret = ret;
391 lo_rw_aio_do_completion(cmd);
392}
393
394static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
395 loff_t pos, int rw)
396{
397 struct iov_iter iter;
398 struct req_iterator rq_iter;
399 struct bio_vec *bvec;
400 struct request *rq = blk_mq_rq_from_pdu(cmd);
401 struct bio *bio = rq->bio;
402 struct file *file = lo->lo_backing_file;
403 struct bio_vec tmp;
404 unsigned int offset;
405 int nr_bvec = 0;
406 int ret;
407
408 rq_for_each_bvec(tmp, rq, rq_iter)
409 nr_bvec++;
410
411 if (rq->bio != rq->biotail) {
412
413 bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec),
414 GFP_NOIO);
415 if (!bvec)
416 return -EIO;
417 cmd->bvec = bvec;
418
419 /*
420 * The bios of the request may be started from the middle of
421 * the 'bvec' because of bio splitting, so we can't directly
422 * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec
423 * API will take care of all details for us.
424 */
425 rq_for_each_bvec(tmp, rq, rq_iter) {
426 *bvec = tmp;
427 bvec++;
428 }
429 bvec = cmd->bvec;
430 offset = 0;
431 } else {
432 /*
433 * Same here, this bio may be started from the middle of the
434 * 'bvec' because of bio splitting, so offset from the bvec
435 * must be passed to iov iterator
436 */
437 offset = bio->bi_iter.bi_bvec_done;
438 bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
439 }
440 atomic_set(&cmd->ref, 2);
441
442 iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq));
443 iter.iov_offset = offset;
444
445 cmd->iocb.ki_pos = pos;
446 cmd->iocb.ki_filp = file;
447 cmd->iocb.ki_complete = lo_rw_aio_complete;
448 cmd->iocb.ki_flags = IOCB_DIRECT;
449 cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
450
451 if (rw == ITER_SOURCE)
452 ret = call_write_iter(file, &cmd->iocb, &iter);
453 else
454 ret = call_read_iter(file, &cmd->iocb, &iter);
455
456 lo_rw_aio_do_completion(cmd);
457
458 if (ret != -EIOCBQUEUED)
459 lo_rw_aio_complete(&cmd->iocb, ret);
460 return 0;
461}
462
463static int do_req_filebacked(struct loop_device *lo, struct request *rq)
464{
465 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
466 loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
467
468 /*
469 * lo_write_simple and lo_read_simple should have been covered
470 * by io submit style function like lo_rw_aio(), one blocker
471 * is that lo_read_simple() need to call flush_dcache_page after
472 * the page is written from kernel, and it isn't easy to handle
473 * this in io submit style function which submits all segments
474 * of the req at one time. And direct read IO doesn't need to
475 * run flush_dcache_page().
476 */
477 switch (req_op(rq)) {
478 case REQ_OP_FLUSH:
479 return lo_req_flush(lo, rq);
480 case REQ_OP_WRITE_ZEROES:
481 /*
482 * If the caller doesn't want deallocation, call zeroout to
483 * write zeroes the range. Otherwise, punch them out.
484 */
485 return lo_fallocate(lo, rq, pos,
486 (rq->cmd_flags & REQ_NOUNMAP) ?
487 FALLOC_FL_ZERO_RANGE :
488 FALLOC_FL_PUNCH_HOLE);
489 case REQ_OP_DISCARD:
490 return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE);
491 case REQ_OP_WRITE:
492 if (cmd->use_aio)
493 return lo_rw_aio(lo, cmd, pos, ITER_SOURCE);
494 else
495 return lo_write_simple(lo, rq, pos);
496 case REQ_OP_READ:
497 if (cmd->use_aio)
498 return lo_rw_aio(lo, cmd, pos, ITER_DEST);
499 else
500 return lo_read_simple(lo, rq, pos);
501 default:
502 WARN_ON_ONCE(1);
503 return -EIO;
504 }
505}
506
507static inline void loop_update_dio(struct loop_device *lo)
508{
509 __loop_update_dio(lo, (lo->lo_backing_file->f_flags & O_DIRECT) |
510 lo->use_dio);
511}
512
513static void loop_reread_partitions(struct loop_device *lo)
514{
515 int rc;
516
517 mutex_lock(&lo->lo_disk->open_mutex);
518 rc = bdev_disk_changed(lo->lo_disk, false);
519 mutex_unlock(&lo->lo_disk->open_mutex);
520 if (rc)
521 pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
522 __func__, lo->lo_number, lo->lo_file_name, rc);
523}
524
525static inline int is_loop_device(struct file *file)
526{
527 struct inode *i = file->f_mapping->host;
528
529 return i && S_ISBLK(i->i_mode) && imajor(i) == LOOP_MAJOR;
530}
531
532static int loop_validate_file(struct file *file, struct block_device *bdev)
533{
534 struct inode *inode = file->f_mapping->host;
535 struct file *f = file;
536
537 /* Avoid recursion */
538 while (is_loop_device(f)) {
539 struct loop_device *l;
540
541 lockdep_assert_held(&loop_validate_mutex);
542 if (f->f_mapping->host->i_rdev == bdev->bd_dev)
543 return -EBADF;
544
545 l = I_BDEV(f->f_mapping->host)->bd_disk->private_data;
546 if (l->lo_state != Lo_bound)
547 return -EINVAL;
548 /* Order wrt setting lo->lo_backing_file in loop_configure(). */
549 rmb();
550 f = l->lo_backing_file;
551 }
552 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
553 return -EINVAL;
554 return 0;
555}
556
557/*
558 * loop_change_fd switched the backing store of a loopback device to
559 * a new file. This is useful for operating system installers to free up
560 * the original file and in High Availability environments to switch to
561 * an alternative location for the content in case of server meltdown.
562 * This can only work if the loop device is used read-only, and if the
563 * new backing store is the same size and type as the old backing store.
564 */
565static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
566 unsigned int arg)
567{
568 struct file *file = fget(arg);
569 struct file *old_file;
570 int error;
571 bool partscan;
572 bool is_loop;
573
574 if (!file)
575 return -EBADF;
576
577 /* suppress uevents while reconfiguring the device */
578 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
579
580 is_loop = is_loop_device(file);
581 error = loop_global_lock_killable(lo, is_loop);
582 if (error)
583 goto out_putf;
584 error = -ENXIO;
585 if (lo->lo_state != Lo_bound)
586 goto out_err;
587
588 /* the loop device has to be read-only */
589 error = -EINVAL;
590 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
591 goto out_err;
592
593 error = loop_validate_file(file, bdev);
594 if (error)
595 goto out_err;
596
597 old_file = lo->lo_backing_file;
598
599 error = -EINVAL;
600
601 /* size of the new backing store needs to be the same */
602 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
603 goto out_err;
604
605 /* and ... switch */
606 disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
607 blk_mq_freeze_queue(lo->lo_queue);
608 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
609 lo->lo_backing_file = file;
610 lo->old_gfp_mask = mapping_gfp_mask(file->f_mapping);
611 mapping_set_gfp_mask(file->f_mapping,
612 lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
613 loop_update_dio(lo);
614 blk_mq_unfreeze_queue(lo->lo_queue);
615 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
616 loop_global_unlock(lo, is_loop);
617
618 /*
619 * Flush loop_validate_file() before fput(), for l->lo_backing_file
620 * might be pointing at old_file which might be the last reference.
621 */
622 if (!is_loop) {
623 mutex_lock(&loop_validate_mutex);
624 mutex_unlock(&loop_validate_mutex);
625 }
626 /*
627 * We must drop file reference outside of lo_mutex as dropping
628 * the file ref can take open_mutex which creates circular locking
629 * dependency.
630 */
631 fput(old_file);
632 if (partscan)
633 loop_reread_partitions(lo);
634
635 error = 0;
636done:
637 /* enable and uncork uevent now that we are done */
638 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
639 return error;
640
641out_err:
642 loop_global_unlock(lo, is_loop);
643out_putf:
644 fput(file);
645 goto done;
646}
647
648/* loop sysfs attributes */
649
650static ssize_t loop_attr_show(struct device *dev, char *page,
651 ssize_t (*callback)(struct loop_device *, char *))
652{
653 struct gendisk *disk = dev_to_disk(dev);
654 struct loop_device *lo = disk->private_data;
655
656 return callback(lo, page);
657}
658
659#define LOOP_ATTR_RO(_name) \
660static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
661static ssize_t loop_attr_do_show_##_name(struct device *d, \
662 struct device_attribute *attr, char *b) \
663{ \
664 return loop_attr_show(d, b, loop_attr_##_name##_show); \
665} \
666static struct device_attribute loop_attr_##_name = \
667 __ATTR(_name, 0444, loop_attr_do_show_##_name, NULL);
668
669static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
670{
671 ssize_t ret;
672 char *p = NULL;
673
674 spin_lock_irq(&lo->lo_lock);
675 if (lo->lo_backing_file)
676 p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1);
677 spin_unlock_irq(&lo->lo_lock);
678
679 if (IS_ERR_OR_NULL(p))
680 ret = PTR_ERR(p);
681 else {
682 ret = strlen(p);
683 memmove(buf, p, ret);
684 buf[ret++] = '\n';
685 buf[ret] = 0;
686 }
687
688 return ret;
689}
690
691static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
692{
693 return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_offset);
694}
695
696static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
697{
698 return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
699}
700
701static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
702{
703 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
704
705 return sysfs_emit(buf, "%s\n", autoclear ? "1" : "0");
706}
707
708static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
709{
710 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
711
712 return sysfs_emit(buf, "%s\n", partscan ? "1" : "0");
713}
714
715static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf)
716{
717 int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO);
718
719 return sysfs_emit(buf, "%s\n", dio ? "1" : "0");
720}
721
722LOOP_ATTR_RO(backing_file);
723LOOP_ATTR_RO(offset);
724LOOP_ATTR_RO(sizelimit);
725LOOP_ATTR_RO(autoclear);
726LOOP_ATTR_RO(partscan);
727LOOP_ATTR_RO(dio);
728
729static struct attribute *loop_attrs[] = {
730 &loop_attr_backing_file.attr,
731 &loop_attr_offset.attr,
732 &loop_attr_sizelimit.attr,
733 &loop_attr_autoclear.attr,
734 &loop_attr_partscan.attr,
735 &loop_attr_dio.attr,
736 NULL,
737};
738
739static struct attribute_group loop_attribute_group = {
740 .name = "loop",
741 .attrs= loop_attrs,
742};
743
744static void loop_sysfs_init(struct loop_device *lo)
745{
746 lo->sysfs_inited = !sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
747 &loop_attribute_group);
748}
749
750static void loop_sysfs_exit(struct loop_device *lo)
751{
752 if (lo->sysfs_inited)
753 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
754 &loop_attribute_group);
755}
756
757static void loop_config_discard(struct loop_device *lo)
758{
759 struct file *file = lo->lo_backing_file;
760 struct inode *inode = file->f_mapping->host;
761 struct request_queue *q = lo->lo_queue;
762 u32 granularity, max_discard_sectors;
763
764 /*
765 * If the backing device is a block device, mirror its zeroing
766 * capability. Set the discard sectors to the block device's zeroing
767 * capabilities because loop discards result in blkdev_issue_zeroout(),
768 * not blkdev_issue_discard(). This maintains consistent behavior with
769 * file-backed loop devices: discarded regions read back as zero.
770 */
771 if (S_ISBLK(inode->i_mode)) {
772 struct request_queue *backingq = bdev_get_queue(I_BDEV(inode));
773
774 max_discard_sectors = backingq->limits.max_write_zeroes_sectors;
775 granularity = bdev_discard_granularity(I_BDEV(inode)) ?:
776 queue_physical_block_size(backingq);
777
778 /*
779 * We use punch hole to reclaim the free space used by the
780 * image a.k.a. discard.
781 */
782 } else if (!file->f_op->fallocate) {
783 max_discard_sectors = 0;
784 granularity = 0;
785
786 } else {
787 struct kstatfs sbuf;
788
789 max_discard_sectors = UINT_MAX >> 9;
790 if (!vfs_statfs(&file->f_path, &sbuf))
791 granularity = sbuf.f_bsize;
792 else
793 max_discard_sectors = 0;
794 }
795
796 if (max_discard_sectors) {
797 q->limits.discard_granularity = granularity;
798 blk_queue_max_discard_sectors(q, max_discard_sectors);
799 blk_queue_max_write_zeroes_sectors(q, max_discard_sectors);
800 } else {
801 q->limits.discard_granularity = 0;
802 blk_queue_max_discard_sectors(q, 0);
803 blk_queue_max_write_zeroes_sectors(q, 0);
804 }
805}
806
807struct loop_worker {
808 struct rb_node rb_node;
809 struct work_struct work;
810 struct list_head cmd_list;
811 struct list_head idle_list;
812 struct loop_device *lo;
813 struct cgroup_subsys_state *blkcg_css;
814 unsigned long last_ran_at;
815};
816
817static void loop_workfn(struct work_struct *work);
818
819#ifdef CONFIG_BLK_CGROUP
820static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
821{
822 return !css || css == blkcg_root_css;
823}
824#else
825static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
826{
827 return !css;
828}
829#endif
830
831static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd)
832{
833 struct rb_node **node, *parent = NULL;
834 struct loop_worker *cur_worker, *worker = NULL;
835 struct work_struct *work;
836 struct list_head *cmd_list;
837
838 spin_lock_irq(&lo->lo_work_lock);
839
840 if (queue_on_root_worker(cmd->blkcg_css))
841 goto queue_work;
842
843 node = &lo->worker_tree.rb_node;
844
845 while (*node) {
846 parent = *node;
847 cur_worker = container_of(*node, struct loop_worker, rb_node);
848 if (cur_worker->blkcg_css == cmd->blkcg_css) {
849 worker = cur_worker;
850 break;
851 } else if ((long)cur_worker->blkcg_css < (long)cmd->blkcg_css) {
852 node = &(*node)->rb_left;
853 } else {
854 node = &(*node)->rb_right;
855 }
856 }
857 if (worker)
858 goto queue_work;
859
860 worker = kzalloc(sizeof(struct loop_worker), GFP_NOWAIT | __GFP_NOWARN);
861 /*
862 * In the event we cannot allocate a worker, just queue on the
863 * rootcg worker and issue the I/O as the rootcg
864 */
865 if (!worker) {
866 cmd->blkcg_css = NULL;
867 if (cmd->memcg_css)
868 css_put(cmd->memcg_css);
869 cmd->memcg_css = NULL;
870 goto queue_work;
871 }
872
873 worker->blkcg_css = cmd->blkcg_css;
874 css_get(worker->blkcg_css);
875 INIT_WORK(&worker->work, loop_workfn);
876 INIT_LIST_HEAD(&worker->cmd_list);
877 INIT_LIST_HEAD(&worker->idle_list);
878 worker->lo = lo;
879 rb_link_node(&worker->rb_node, parent, node);
880 rb_insert_color(&worker->rb_node, &lo->worker_tree);
881queue_work:
882 if (worker) {
883 /*
884 * We need to remove from the idle list here while
885 * holding the lock so that the idle timer doesn't
886 * free the worker
887 */
888 if (!list_empty(&worker->idle_list))
889 list_del_init(&worker->idle_list);
890 work = &worker->work;
891 cmd_list = &worker->cmd_list;
892 } else {
893 work = &lo->rootcg_work;
894 cmd_list = &lo->rootcg_cmd_list;
895 }
896 list_add_tail(&cmd->list_entry, cmd_list);
897 queue_work(lo->workqueue, work);
898 spin_unlock_irq(&lo->lo_work_lock);
899}
900
901static void loop_set_timer(struct loop_device *lo)
902{
903 timer_reduce(&lo->timer, jiffies + LOOP_IDLE_WORKER_TIMEOUT);
904}
905
906static void loop_free_idle_workers(struct loop_device *lo, bool delete_all)
907{
908 struct loop_worker *pos, *worker;
909
910 spin_lock_irq(&lo->lo_work_lock);
911 list_for_each_entry_safe(worker, pos, &lo->idle_worker_list,
912 idle_list) {
913 if (!delete_all &&
914 time_is_after_jiffies(worker->last_ran_at +
915 LOOP_IDLE_WORKER_TIMEOUT))
916 break;
917 list_del(&worker->idle_list);
918 rb_erase(&worker->rb_node, &lo->worker_tree);
919 css_put(worker->blkcg_css);
920 kfree(worker);
921 }
922 if (!list_empty(&lo->idle_worker_list))
923 loop_set_timer(lo);
924 spin_unlock_irq(&lo->lo_work_lock);
925}
926
927static void loop_free_idle_workers_timer(struct timer_list *timer)
928{
929 struct loop_device *lo = container_of(timer, struct loop_device, timer);
930
931 return loop_free_idle_workers(lo, false);
932}
933
934static void loop_update_rotational(struct loop_device *lo)
935{
936 struct file *file = lo->lo_backing_file;
937 struct inode *file_inode = file->f_mapping->host;
938 struct block_device *file_bdev = file_inode->i_sb->s_bdev;
939 struct request_queue *q = lo->lo_queue;
940 bool nonrot = true;
941
942 /* not all filesystems (e.g. tmpfs) have a sb->s_bdev */
943 if (file_bdev)
944 nonrot = bdev_nonrot(file_bdev);
945
946 if (nonrot)
947 blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
948 else
949 blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
950}
951
952/**
953 * loop_set_status_from_info - configure device from loop_info
954 * @lo: struct loop_device to configure
955 * @info: struct loop_info64 to configure the device with
956 *
957 * Configures the loop device parameters according to the passed
958 * in loop_info64 configuration.
959 */
960static int
961loop_set_status_from_info(struct loop_device *lo,
962 const struct loop_info64 *info)
963{
964 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
965 return -EINVAL;
966
967 switch (info->lo_encrypt_type) {
968 case LO_CRYPT_NONE:
969 break;
970 case LO_CRYPT_XOR:
971 pr_warn("support for the xor transformation has been removed.\n");
972 return -EINVAL;
973 case LO_CRYPT_CRYPTOAPI:
974 pr_warn("support for cryptoloop has been removed. Use dm-crypt instead.\n");
975 return -EINVAL;
976 default:
977 return -EINVAL;
978 }
979
980 lo->lo_offset = info->lo_offset;
981 lo->lo_sizelimit = info->lo_sizelimit;
982
983 /* loff_t vars have been assigned __u64 */
984 if (lo->lo_offset < 0 || lo->lo_sizelimit < 0)
985 return -EOVERFLOW;
986
987 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
988 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
989 lo->lo_flags = info->lo_flags;
990 return 0;
991}
992
993static int loop_configure(struct loop_device *lo, fmode_t mode,
994 struct block_device *bdev,
995 const struct loop_config *config)
996{
997 struct file *file = fget(config->fd);
998 struct inode *inode;
999 struct address_space *mapping;
1000 int error;
1001 loff_t size;
1002 bool partscan;
1003 unsigned short bsize;
1004 bool is_loop;
1005
1006 if (!file)
1007 return -EBADF;
1008 is_loop = is_loop_device(file);
1009
1010 /* This is safe, since we have a reference from open(). */
1011 __module_get(THIS_MODULE);
1012
1013 /* suppress uevents while reconfiguring the device */
1014 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
1015
1016 /*
1017 * If we don't hold exclusive handle for the device, upgrade to it
1018 * here to avoid changing device under exclusive owner.
1019 */
1020 if (!(mode & FMODE_EXCL)) {
1021 error = bd_prepare_to_claim(bdev, loop_configure);
1022 if (error)
1023 goto out_putf;
1024 }
1025
1026 error = loop_global_lock_killable(lo, is_loop);
1027 if (error)
1028 goto out_bdev;
1029
1030 error = -EBUSY;
1031 if (lo->lo_state != Lo_unbound)
1032 goto out_unlock;
1033
1034 error = loop_validate_file(file, bdev);
1035 if (error)
1036 goto out_unlock;
1037
1038 mapping = file->f_mapping;
1039 inode = mapping->host;
1040
1041 if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) {
1042 error = -EINVAL;
1043 goto out_unlock;
1044 }
1045
1046 if (config->block_size) {
1047 error = blk_validate_block_size(config->block_size);
1048 if (error)
1049 goto out_unlock;
1050 }
1051
1052 error = loop_set_status_from_info(lo, &config->info);
1053 if (error)
1054 goto out_unlock;
1055
1056 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
1057 !file->f_op->write_iter)
1058 lo->lo_flags |= LO_FLAGS_READ_ONLY;
1059
1060 if (!lo->workqueue) {
1061 lo->workqueue = alloc_workqueue("loop%d",
1062 WQ_UNBOUND | WQ_FREEZABLE,
1063 0, lo->lo_number);
1064 if (!lo->workqueue) {
1065 error = -ENOMEM;
1066 goto out_unlock;
1067 }
1068 }
1069
1070 disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
1071 set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0);
1072
1073 lo->use_dio = lo->lo_flags & LO_FLAGS_DIRECT_IO;
1074 lo->lo_device = bdev;
1075 lo->lo_backing_file = file;
1076 lo->old_gfp_mask = mapping_gfp_mask(mapping);
1077 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
1078
1079 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
1080 blk_queue_write_cache(lo->lo_queue, true, false);
1081
1082 if (config->block_size)
1083 bsize = config->block_size;
1084 else if ((lo->lo_backing_file->f_flags & O_DIRECT) && inode->i_sb->s_bdev)
1085 /* In case of direct I/O, match underlying block size */
1086 bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
1087 else
1088 bsize = 512;
1089
1090 blk_queue_logical_block_size(lo->lo_queue, bsize);
1091 blk_queue_physical_block_size(lo->lo_queue, bsize);
1092 blk_queue_io_min(lo->lo_queue, bsize);
1093
1094 loop_config_discard(lo);
1095 loop_update_rotational(lo);
1096 loop_update_dio(lo);
1097 loop_sysfs_init(lo);
1098
1099 size = get_loop_size(lo, file);
1100 loop_set_size(lo, size);
1101
1102 /* Order wrt reading lo_state in loop_validate_file(). */
1103 wmb();
1104
1105 lo->lo_state = Lo_bound;
1106 if (part_shift)
1107 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1108 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
1109 if (partscan)
1110 clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1111
1112 loop_global_unlock(lo, is_loop);
1113 if (partscan)
1114 loop_reread_partitions(lo);
1115 if (!(mode & FMODE_EXCL))
1116 bd_abort_claiming(bdev, loop_configure);
1117
1118 error = 0;
1119done:
1120 /* enable and uncork uevent now that we are done */
1121 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
1122 return error;
1123
1124out_unlock:
1125 loop_global_unlock(lo, is_loop);
1126out_bdev:
1127 if (!(mode & FMODE_EXCL))
1128 bd_abort_claiming(bdev, loop_configure);
1129out_putf:
1130 fput(file);
1131 /* This is safe: open() is still holding a reference. */
1132 module_put(THIS_MODULE);
1133 goto done;
1134}
1135
1136static void __loop_clr_fd(struct loop_device *lo, bool release)
1137{
1138 struct file *filp;
1139 gfp_t gfp = lo->old_gfp_mask;
1140
1141 if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags))
1142 blk_queue_write_cache(lo->lo_queue, false, false);
1143
1144 /*
1145 * Freeze the request queue when unbinding on a live file descriptor and
1146 * thus an open device. When called from ->release we are guaranteed
1147 * that there is no I/O in progress already.
1148 */
1149 if (!release)
1150 blk_mq_freeze_queue(lo->lo_queue);
1151
1152 spin_lock_irq(&lo->lo_lock);
1153 filp = lo->lo_backing_file;
1154 lo->lo_backing_file = NULL;
1155 spin_unlock_irq(&lo->lo_lock);
1156
1157 lo->lo_device = NULL;
1158 lo->lo_offset = 0;
1159 lo->lo_sizelimit = 0;
1160 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1161 blk_queue_logical_block_size(lo->lo_queue, 512);
1162 blk_queue_physical_block_size(lo->lo_queue, 512);
1163 blk_queue_io_min(lo->lo_queue, 512);
1164 invalidate_disk(lo->lo_disk);
1165 loop_sysfs_exit(lo);
1166 /* let user-space know about this change */
1167 kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
1168 mapping_set_gfp_mask(filp->f_mapping, gfp);
1169 /* This is safe: open() is still holding a reference. */
1170 module_put(THIS_MODULE);
1171 if (!release)
1172 blk_mq_unfreeze_queue(lo->lo_queue);
1173
1174 disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
1175
1176 if (lo->lo_flags & LO_FLAGS_PARTSCAN) {
1177 int err;
1178
1179 /*
1180 * open_mutex has been held already in release path, so don't
1181 * acquire it if this function is called in such case.
1182 *
1183 * If the reread partition isn't from release path, lo_refcnt
1184 * must be at least one and it can only become zero when the
1185 * current holder is released.
1186 */
1187 if (!release)
1188 mutex_lock(&lo->lo_disk->open_mutex);
1189 err = bdev_disk_changed(lo->lo_disk, false);
1190 if (!release)
1191 mutex_unlock(&lo->lo_disk->open_mutex);
1192 if (err)
1193 pr_warn("%s: partition scan of loop%d failed (rc=%d)\n",
1194 __func__, lo->lo_number, err);
1195 /* Device is gone, no point in returning error */
1196 }
1197
1198 /*
1199 * lo->lo_state is set to Lo_unbound here after above partscan has
1200 * finished. There cannot be anybody else entering __loop_clr_fd() as
1201 * Lo_rundown state protects us from all the other places trying to
1202 * change the 'lo' device.
1203 */
1204 lo->lo_flags = 0;
1205 if (!part_shift)
1206 set_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1207 mutex_lock(&lo->lo_mutex);
1208 lo->lo_state = Lo_unbound;
1209 mutex_unlock(&lo->lo_mutex);
1210
1211 /*
1212 * Need not hold lo_mutex to fput backing file. Calling fput holding
1213 * lo_mutex triggers a circular lock dependency possibility warning as
1214 * fput can take open_mutex which is usually taken before lo_mutex.
1215 */
1216 fput(filp);
1217}
1218
1219static int loop_clr_fd(struct loop_device *lo)
1220{
1221 int err;
1222
1223 /*
1224 * Since lo_ioctl() is called without locks held, it is possible that
1225 * loop_configure()/loop_change_fd() and loop_clr_fd() run in parallel.
1226 *
1227 * Therefore, use global lock when setting Lo_rundown state in order to
1228 * make sure that loop_validate_file() will fail if the "struct file"
1229 * which loop_configure()/loop_change_fd() found via fget() was this
1230 * loop device.
1231 */
1232 err = loop_global_lock_killable(lo, true);
1233 if (err)
1234 return err;
1235 if (lo->lo_state != Lo_bound) {
1236 loop_global_unlock(lo, true);
1237 return -ENXIO;
1238 }
1239 /*
1240 * If we've explicitly asked to tear down the loop device,
1241 * and it has an elevated reference count, set it for auto-teardown when
1242 * the last reference goes away. This stops $!~#$@ udev from
1243 * preventing teardown because it decided that it needs to run blkid on
1244 * the loopback device whenever they appear. xfstests is notorious for
1245 * failing tests because blkid via udev races with a losetup
1246 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
1247 * command to fail with EBUSY.
1248 */
1249 if (disk_openers(lo->lo_disk) > 1) {
1250 lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
1251 loop_global_unlock(lo, true);
1252 return 0;
1253 }
1254 lo->lo_state = Lo_rundown;
1255 loop_global_unlock(lo, true);
1256
1257 __loop_clr_fd(lo, false);
1258 return 0;
1259}
1260
1261static int
1262loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1263{
1264 int err;
1265 int prev_lo_flags;
1266 bool partscan = false;
1267 bool size_changed = false;
1268
1269 err = mutex_lock_killable(&lo->lo_mutex);
1270 if (err)
1271 return err;
1272 if (lo->lo_state != Lo_bound) {
1273 err = -ENXIO;
1274 goto out_unlock;
1275 }
1276
1277 if (lo->lo_offset != info->lo_offset ||
1278 lo->lo_sizelimit != info->lo_sizelimit) {
1279 size_changed = true;
1280 sync_blockdev(lo->lo_device);
1281 invalidate_bdev(lo->lo_device);
1282 }
1283
1284 /* I/O need to be drained during transfer transition */
1285 blk_mq_freeze_queue(lo->lo_queue);
1286
1287 prev_lo_flags = lo->lo_flags;
1288
1289 err = loop_set_status_from_info(lo, info);
1290 if (err)
1291 goto out_unfreeze;
1292
1293 /* Mask out flags that can't be set using LOOP_SET_STATUS. */
1294 lo->lo_flags &= LOOP_SET_STATUS_SETTABLE_FLAGS;
1295 /* For those flags, use the previous values instead */
1296 lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_SETTABLE_FLAGS;
1297 /* For flags that can't be cleared, use previous values too */
1298 lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_CLEARABLE_FLAGS;
1299
1300 if (size_changed) {
1301 loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit,
1302 lo->lo_backing_file);
1303 loop_set_size(lo, new_size);
1304 }
1305
1306 loop_config_discard(lo);
1307
1308 /* update dio if lo_offset or transfer is changed */
1309 __loop_update_dio(lo, lo->use_dio);
1310
1311out_unfreeze:
1312 blk_mq_unfreeze_queue(lo->lo_queue);
1313
1314 if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) &&
1315 !(prev_lo_flags & LO_FLAGS_PARTSCAN)) {
1316 clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1317 partscan = true;
1318 }
1319out_unlock:
1320 mutex_unlock(&lo->lo_mutex);
1321 if (partscan)
1322 loop_reread_partitions(lo);
1323
1324 return err;
1325}
1326
1327static int
1328loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1329{
1330 struct path path;
1331 struct kstat stat;
1332 int ret;
1333
1334 ret = mutex_lock_killable(&lo->lo_mutex);
1335 if (ret)
1336 return ret;
1337 if (lo->lo_state != Lo_bound) {
1338 mutex_unlock(&lo->lo_mutex);
1339 return -ENXIO;
1340 }
1341
1342 memset(info, 0, sizeof(*info));
1343 info->lo_number = lo->lo_number;
1344 info->lo_offset = lo->lo_offset;
1345 info->lo_sizelimit = lo->lo_sizelimit;
1346 info->lo_flags = lo->lo_flags;
1347 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1348
1349 /* Drop lo_mutex while we call into the filesystem. */
1350 path = lo->lo_backing_file->f_path;
1351 path_get(&path);
1352 mutex_unlock(&lo->lo_mutex);
1353 ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT);
1354 if (!ret) {
1355 info->lo_device = huge_encode_dev(stat.dev);
1356 info->lo_inode = stat.ino;
1357 info->lo_rdevice = huge_encode_dev(stat.rdev);
1358 }
1359 path_put(&path);
1360 return ret;
1361}
1362
1363static void
1364loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1365{
1366 memset(info64, 0, sizeof(*info64));
1367 info64->lo_number = info->lo_number;
1368 info64->lo_device = info->lo_device;
1369 info64->lo_inode = info->lo_inode;
1370 info64->lo_rdevice = info->lo_rdevice;
1371 info64->lo_offset = info->lo_offset;
1372 info64->lo_sizelimit = 0;
1373 info64->lo_flags = info->lo_flags;
1374 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1375}
1376
1377static int
1378loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1379{
1380 memset(info, 0, sizeof(*info));
1381 info->lo_number = info64->lo_number;
1382 info->lo_device = info64->lo_device;
1383 info->lo_inode = info64->lo_inode;
1384 info->lo_rdevice = info64->lo_rdevice;
1385 info->lo_offset = info64->lo_offset;
1386 info->lo_flags = info64->lo_flags;
1387 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1388
1389 /* error in case values were truncated */
1390 if (info->lo_device != info64->lo_device ||
1391 info->lo_rdevice != info64->lo_rdevice ||
1392 info->lo_inode != info64->lo_inode ||
1393 info->lo_offset != info64->lo_offset)
1394 return -EOVERFLOW;
1395
1396 return 0;
1397}
1398
1399static int
1400loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1401{
1402 struct loop_info info;
1403 struct loop_info64 info64;
1404
1405 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1406 return -EFAULT;
1407 loop_info64_from_old(&info, &info64);
1408 return loop_set_status(lo, &info64);
1409}
1410
1411static int
1412loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1413{
1414 struct loop_info64 info64;
1415
1416 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1417 return -EFAULT;
1418 return loop_set_status(lo, &info64);
1419}
1420
1421static int
1422loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1423 struct loop_info info;
1424 struct loop_info64 info64;
1425 int err;
1426
1427 if (!arg)
1428 return -EINVAL;
1429 err = loop_get_status(lo, &info64);
1430 if (!err)
1431 err = loop_info64_to_old(&info64, &info);
1432 if (!err && copy_to_user(arg, &info, sizeof(info)))
1433 err = -EFAULT;
1434
1435 return err;
1436}
1437
1438static int
1439loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1440 struct loop_info64 info64;
1441 int err;
1442
1443 if (!arg)
1444 return -EINVAL;
1445 err = loop_get_status(lo, &info64);
1446 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1447 err = -EFAULT;
1448
1449 return err;
1450}
1451
1452static int loop_set_capacity(struct loop_device *lo)
1453{
1454 loff_t size;
1455
1456 if (unlikely(lo->lo_state != Lo_bound))
1457 return -ENXIO;
1458
1459 size = get_loop_size(lo, lo->lo_backing_file);
1460 loop_set_size(lo, size);
1461
1462 return 0;
1463}
1464
1465static int loop_set_dio(struct loop_device *lo, unsigned long arg)
1466{
1467 int error = -ENXIO;
1468 if (lo->lo_state != Lo_bound)
1469 goto out;
1470
1471 __loop_update_dio(lo, !!arg);
1472 if (lo->use_dio == !!arg)
1473 return 0;
1474 error = -EINVAL;
1475 out:
1476 return error;
1477}
1478
1479static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
1480{
1481 int err = 0;
1482
1483 if (lo->lo_state != Lo_bound)
1484 return -ENXIO;
1485
1486 err = blk_validate_block_size(arg);
1487 if (err)
1488 return err;
1489
1490 if (lo->lo_queue->limits.logical_block_size == arg)
1491 return 0;
1492
1493 sync_blockdev(lo->lo_device);
1494 invalidate_bdev(lo->lo_device);
1495
1496 blk_mq_freeze_queue(lo->lo_queue);
1497 blk_queue_logical_block_size(lo->lo_queue, arg);
1498 blk_queue_physical_block_size(lo->lo_queue, arg);
1499 blk_queue_io_min(lo->lo_queue, arg);
1500 loop_update_dio(lo);
1501 blk_mq_unfreeze_queue(lo->lo_queue);
1502
1503 return err;
1504}
1505
1506static int lo_simple_ioctl(struct loop_device *lo, unsigned int cmd,
1507 unsigned long arg)
1508{
1509 int err;
1510
1511 err = mutex_lock_killable(&lo->lo_mutex);
1512 if (err)
1513 return err;
1514 switch (cmd) {
1515 case LOOP_SET_CAPACITY:
1516 err = loop_set_capacity(lo);
1517 break;
1518 case LOOP_SET_DIRECT_IO:
1519 err = loop_set_dio(lo, arg);
1520 break;
1521 case LOOP_SET_BLOCK_SIZE:
1522 err = loop_set_block_size(lo, arg);
1523 break;
1524 default:
1525 err = -EINVAL;
1526 }
1527 mutex_unlock(&lo->lo_mutex);
1528 return err;
1529}
1530
1531static int lo_ioctl(struct block_device *bdev, fmode_t mode,
1532 unsigned int cmd, unsigned long arg)
1533{
1534 struct loop_device *lo = bdev->bd_disk->private_data;
1535 void __user *argp = (void __user *) arg;
1536 int err;
1537
1538 switch (cmd) {
1539 case LOOP_SET_FD: {
1540 /*
1541 * Legacy case - pass in a zeroed out struct loop_config with
1542 * only the file descriptor set , which corresponds with the
1543 * default parameters we'd have used otherwise.
1544 */
1545 struct loop_config config;
1546
1547 memset(&config, 0, sizeof(config));
1548 config.fd = arg;
1549
1550 return loop_configure(lo, mode, bdev, &config);
1551 }
1552 case LOOP_CONFIGURE: {
1553 struct loop_config config;
1554
1555 if (copy_from_user(&config, argp, sizeof(config)))
1556 return -EFAULT;
1557
1558 return loop_configure(lo, mode, bdev, &config);
1559 }
1560 case LOOP_CHANGE_FD:
1561 return loop_change_fd(lo, bdev, arg);
1562 case LOOP_CLR_FD:
1563 return loop_clr_fd(lo);
1564 case LOOP_SET_STATUS:
1565 err = -EPERM;
1566 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
1567 err = loop_set_status_old(lo, argp);
1568 }
1569 break;
1570 case LOOP_GET_STATUS:
1571 return loop_get_status_old(lo, argp);
1572 case LOOP_SET_STATUS64:
1573 err = -EPERM;
1574 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
1575 err = loop_set_status64(lo, argp);
1576 }
1577 break;
1578 case LOOP_GET_STATUS64:
1579 return loop_get_status64(lo, argp);
1580 case LOOP_SET_CAPACITY:
1581 case LOOP_SET_DIRECT_IO:
1582 case LOOP_SET_BLOCK_SIZE:
1583 if (!(mode & FMODE_WRITE) && !capable(CAP_SYS_ADMIN))
1584 return -EPERM;
1585 fallthrough;
1586 default:
1587 err = lo_simple_ioctl(lo, cmd, arg);
1588 break;
1589 }
1590
1591 return err;
1592}
1593
1594#ifdef CONFIG_COMPAT
1595struct compat_loop_info {
1596 compat_int_t lo_number; /* ioctl r/o */
1597 compat_dev_t lo_device; /* ioctl r/o */
1598 compat_ulong_t lo_inode; /* ioctl r/o */
1599 compat_dev_t lo_rdevice; /* ioctl r/o */
1600 compat_int_t lo_offset;
1601 compat_int_t lo_encrypt_type; /* obsolete, ignored */
1602 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1603 compat_int_t lo_flags; /* ioctl r/o */
1604 char lo_name[LO_NAME_SIZE];
1605 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1606 compat_ulong_t lo_init[2];
1607 char reserved[4];
1608};
1609
1610/*
1611 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1612 * - noinlined to reduce stack space usage in main part of driver
1613 */
1614static noinline int
1615loop_info64_from_compat(const struct compat_loop_info __user *arg,
1616 struct loop_info64 *info64)
1617{
1618 struct compat_loop_info info;
1619
1620 if (copy_from_user(&info, arg, sizeof(info)))
1621 return -EFAULT;
1622
1623 memset(info64, 0, sizeof(*info64));
1624 info64->lo_number = info.lo_number;
1625 info64->lo_device = info.lo_device;
1626 info64->lo_inode = info.lo_inode;
1627 info64->lo_rdevice = info.lo_rdevice;
1628 info64->lo_offset = info.lo_offset;
1629 info64->lo_sizelimit = 0;
1630 info64->lo_flags = info.lo_flags;
1631 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1632 return 0;
1633}
1634
1635/*
1636 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1637 * - noinlined to reduce stack space usage in main part of driver
1638 */
1639static noinline int
1640loop_info64_to_compat(const struct loop_info64 *info64,
1641 struct compat_loop_info __user *arg)
1642{
1643 struct compat_loop_info info;
1644
1645 memset(&info, 0, sizeof(info));
1646 info.lo_number = info64->lo_number;
1647 info.lo_device = info64->lo_device;
1648 info.lo_inode = info64->lo_inode;
1649 info.lo_rdevice = info64->lo_rdevice;
1650 info.lo_offset = info64->lo_offset;
1651 info.lo_flags = info64->lo_flags;
1652 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1653
1654 /* error in case values were truncated */
1655 if (info.lo_device != info64->lo_device ||
1656 info.lo_rdevice != info64->lo_rdevice ||
1657 info.lo_inode != info64->lo_inode ||
1658 info.lo_offset != info64->lo_offset)
1659 return -EOVERFLOW;
1660
1661 if (copy_to_user(arg, &info, sizeof(info)))
1662 return -EFAULT;
1663 return 0;
1664}
1665
1666static int
1667loop_set_status_compat(struct loop_device *lo,
1668 const struct compat_loop_info __user *arg)
1669{
1670 struct loop_info64 info64;
1671 int ret;
1672
1673 ret = loop_info64_from_compat(arg, &info64);
1674 if (ret < 0)
1675 return ret;
1676 return loop_set_status(lo, &info64);
1677}
1678
1679static int
1680loop_get_status_compat(struct loop_device *lo,
1681 struct compat_loop_info __user *arg)
1682{
1683 struct loop_info64 info64;
1684 int err;
1685
1686 if (!arg)
1687 return -EINVAL;
1688 err = loop_get_status(lo, &info64);
1689 if (!err)
1690 err = loop_info64_to_compat(&info64, arg);
1691 return err;
1692}
1693
1694static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1695 unsigned int cmd, unsigned long arg)
1696{
1697 struct loop_device *lo = bdev->bd_disk->private_data;
1698 int err;
1699
1700 switch(cmd) {
1701 case LOOP_SET_STATUS:
1702 err = loop_set_status_compat(lo,
1703 (const struct compat_loop_info __user *)arg);
1704 break;
1705 case LOOP_GET_STATUS:
1706 err = loop_get_status_compat(lo,
1707 (struct compat_loop_info __user *)arg);
1708 break;
1709 case LOOP_SET_CAPACITY:
1710 case LOOP_CLR_FD:
1711 case LOOP_GET_STATUS64:
1712 case LOOP_SET_STATUS64:
1713 case LOOP_CONFIGURE:
1714 arg = (unsigned long) compat_ptr(arg);
1715 fallthrough;
1716 case LOOP_SET_FD:
1717 case LOOP_CHANGE_FD:
1718 case LOOP_SET_BLOCK_SIZE:
1719 case LOOP_SET_DIRECT_IO:
1720 err = lo_ioctl(bdev, mode, cmd, arg);
1721 break;
1722 default:
1723 err = -ENOIOCTLCMD;
1724 break;
1725 }
1726 return err;
1727}
1728#endif
1729
1730static void lo_release(struct gendisk *disk, fmode_t mode)
1731{
1732 struct loop_device *lo = disk->private_data;
1733
1734 if (disk_openers(disk) > 0)
1735 return;
1736
1737 mutex_lock(&lo->lo_mutex);
1738 if (lo->lo_state == Lo_bound && (lo->lo_flags & LO_FLAGS_AUTOCLEAR)) {
1739 lo->lo_state = Lo_rundown;
1740 mutex_unlock(&lo->lo_mutex);
1741 /*
1742 * In autoclear mode, stop the loop thread
1743 * and remove configuration after last close.
1744 */
1745 __loop_clr_fd(lo, true);
1746 return;
1747 }
1748 mutex_unlock(&lo->lo_mutex);
1749}
1750
1751static void lo_free_disk(struct gendisk *disk)
1752{
1753 struct loop_device *lo = disk->private_data;
1754
1755 if (lo->workqueue)
1756 destroy_workqueue(lo->workqueue);
1757 loop_free_idle_workers(lo, true);
1758 timer_shutdown_sync(&lo->timer);
1759 mutex_destroy(&lo->lo_mutex);
1760 kfree(lo);
1761}
1762
1763static const struct block_device_operations lo_fops = {
1764 .owner = THIS_MODULE,
1765 .release = lo_release,
1766 .ioctl = lo_ioctl,
1767#ifdef CONFIG_COMPAT
1768 .compat_ioctl = lo_compat_ioctl,
1769#endif
1770 .free_disk = lo_free_disk,
1771};
1772
1773/*
1774 * And now the modules code and kernel interface.
1775 */
1776
1777/*
1778 * If max_loop is specified, create that many devices upfront.
1779 * This also becomes a hard limit. If max_loop is not specified,
1780 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1781 * init time. Loop devices can be requested on-demand with the
1782 * /dev/loop-control interface, or be instantiated by accessing
1783 * a 'dead' device node.
1784 */
1785static int max_loop = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1786module_param(max_loop, int, 0444);
1787MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1788module_param(max_part, int, 0444);
1789MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1790
1791static int hw_queue_depth = LOOP_DEFAULT_HW_Q_DEPTH;
1792
1793static int loop_set_hw_queue_depth(const char *s, const struct kernel_param *p)
1794{
1795 int ret = kstrtoint(s, 10, &hw_queue_depth);
1796
1797 return (ret || (hw_queue_depth < 1)) ? -EINVAL : 0;
1798}
1799
1800static const struct kernel_param_ops loop_hw_qdepth_param_ops = {
1801 .set = loop_set_hw_queue_depth,
1802 .get = param_get_int,
1803};
1804
1805device_param_cb(hw_queue_depth, &loop_hw_qdepth_param_ops, &hw_queue_depth, 0444);
1806MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: 128");
1807
1808MODULE_LICENSE("GPL");
1809MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1810
1811static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
1812 const struct blk_mq_queue_data *bd)
1813{
1814 struct request *rq = bd->rq;
1815 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
1816 struct loop_device *lo = rq->q->queuedata;
1817
1818 blk_mq_start_request(rq);
1819
1820 if (lo->lo_state != Lo_bound)
1821 return BLK_STS_IOERR;
1822
1823 switch (req_op(rq)) {
1824 case REQ_OP_FLUSH:
1825 case REQ_OP_DISCARD:
1826 case REQ_OP_WRITE_ZEROES:
1827 cmd->use_aio = false;
1828 break;
1829 default:
1830 cmd->use_aio = lo->use_dio;
1831 break;
1832 }
1833
1834 /* always use the first bio's css */
1835 cmd->blkcg_css = NULL;
1836 cmd->memcg_css = NULL;
1837#ifdef CONFIG_BLK_CGROUP
1838 if (rq->bio) {
1839 cmd->blkcg_css = bio_blkcg_css(rq->bio);
1840#ifdef CONFIG_MEMCG
1841 if (cmd->blkcg_css) {
1842 cmd->memcg_css =
1843 cgroup_get_e_css(cmd->blkcg_css->cgroup,
1844 &memory_cgrp_subsys);
1845 }
1846#endif
1847 }
1848#endif
1849 loop_queue_work(lo, cmd);
1850
1851 return BLK_STS_OK;
1852}
1853
1854static void loop_handle_cmd(struct loop_cmd *cmd)
1855{
1856 struct request *rq = blk_mq_rq_from_pdu(cmd);
1857 const bool write = op_is_write(req_op(rq));
1858 struct loop_device *lo = rq->q->queuedata;
1859 int ret = 0;
1860 struct mem_cgroup *old_memcg = NULL;
1861
1862 if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) {
1863 ret = -EIO;
1864 goto failed;
1865 }
1866
1867 if (cmd->blkcg_css)
1868 kthread_associate_blkcg(cmd->blkcg_css);
1869 if (cmd->memcg_css)
1870 old_memcg = set_active_memcg(
1871 mem_cgroup_from_css(cmd->memcg_css));
1872
1873 ret = do_req_filebacked(lo, rq);
1874
1875 if (cmd->blkcg_css)
1876 kthread_associate_blkcg(NULL);
1877
1878 if (cmd->memcg_css) {
1879 set_active_memcg(old_memcg);
1880 css_put(cmd->memcg_css);
1881 }
1882 failed:
1883 /* complete non-aio request */
1884 if (!cmd->use_aio || ret) {
1885 if (ret == -EOPNOTSUPP)
1886 cmd->ret = ret;
1887 else
1888 cmd->ret = ret ? -EIO : 0;
1889 if (likely(!blk_should_fake_timeout(rq->q)))
1890 blk_mq_complete_request(rq);
1891 }
1892}
1893
1894static void loop_process_work(struct loop_worker *worker,
1895 struct list_head *cmd_list, struct loop_device *lo)
1896{
1897 int orig_flags = current->flags;
1898 struct loop_cmd *cmd;
1899
1900 current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO;
1901 spin_lock_irq(&lo->lo_work_lock);
1902 while (!list_empty(cmd_list)) {
1903 cmd = container_of(
1904 cmd_list->next, struct loop_cmd, list_entry);
1905 list_del(cmd_list->next);
1906 spin_unlock_irq(&lo->lo_work_lock);
1907
1908 loop_handle_cmd(cmd);
1909 cond_resched();
1910
1911 spin_lock_irq(&lo->lo_work_lock);
1912 }
1913
1914 /*
1915 * We only add to the idle list if there are no pending cmds
1916 * *and* the worker will not run again which ensures that it
1917 * is safe to free any worker on the idle list
1918 */
1919 if (worker && !work_pending(&worker->work)) {
1920 worker->last_ran_at = jiffies;
1921 list_add_tail(&worker->idle_list, &lo->idle_worker_list);
1922 loop_set_timer(lo);
1923 }
1924 spin_unlock_irq(&lo->lo_work_lock);
1925 current->flags = orig_flags;
1926}
1927
1928static void loop_workfn(struct work_struct *work)
1929{
1930 struct loop_worker *worker =
1931 container_of(work, struct loop_worker, work);
1932 loop_process_work(worker, &worker->cmd_list, worker->lo);
1933}
1934
1935static void loop_rootcg_workfn(struct work_struct *work)
1936{
1937 struct loop_device *lo =
1938 container_of(work, struct loop_device, rootcg_work);
1939 loop_process_work(NULL, &lo->rootcg_cmd_list, lo);
1940}
1941
1942static const struct blk_mq_ops loop_mq_ops = {
1943 .queue_rq = loop_queue_rq,
1944 .complete = lo_complete_rq,
1945};
1946
1947static int loop_add(int i)
1948{
1949 struct loop_device *lo;
1950 struct gendisk *disk;
1951 int err;
1952
1953 err = -ENOMEM;
1954 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1955 if (!lo)
1956 goto out;
1957 lo->worker_tree = RB_ROOT;
1958 INIT_LIST_HEAD(&lo->idle_worker_list);
1959 timer_setup(&lo->timer, loop_free_idle_workers_timer, TIMER_DEFERRABLE);
1960 lo->lo_state = Lo_unbound;
1961
1962 err = mutex_lock_killable(&loop_ctl_mutex);
1963 if (err)
1964 goto out_free_dev;
1965
1966 /* allocate id, if @id >= 0, we're requesting that specific id */
1967 if (i >= 0) {
1968 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
1969 if (err == -ENOSPC)
1970 err = -EEXIST;
1971 } else {
1972 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
1973 }
1974 mutex_unlock(&loop_ctl_mutex);
1975 if (err < 0)
1976 goto out_free_dev;
1977 i = err;
1978
1979 lo->tag_set.ops = &loop_mq_ops;
1980 lo->tag_set.nr_hw_queues = 1;
1981 lo->tag_set.queue_depth = hw_queue_depth;
1982 lo->tag_set.numa_node = NUMA_NO_NODE;
1983 lo->tag_set.cmd_size = sizeof(struct loop_cmd);
1984 lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING |
1985 BLK_MQ_F_NO_SCHED_BY_DEFAULT;
1986 lo->tag_set.driver_data = lo;
1987
1988 err = blk_mq_alloc_tag_set(&lo->tag_set);
1989 if (err)
1990 goto out_free_idr;
1991
1992 disk = lo->lo_disk = blk_mq_alloc_disk(&lo->tag_set, lo);
1993 if (IS_ERR(disk)) {
1994 err = PTR_ERR(disk);
1995 goto out_cleanup_tags;
1996 }
1997 lo->lo_queue = lo->lo_disk->queue;
1998
1999 blk_queue_max_hw_sectors(lo->lo_queue, BLK_DEF_MAX_SECTORS);
2000
2001 /*
2002 * By default, we do buffer IO, so it doesn't make sense to enable
2003 * merge because the I/O submitted to backing file is handled page by
2004 * page. For directio mode, merge does help to dispatch bigger request
2005 * to underlayer disk. We will enable merge once directio is enabled.
2006 */
2007 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
2008
2009 /*
2010 * Disable partition scanning by default. The in-kernel partition
2011 * scanning can be requested individually per-device during its
2012 * setup. Userspace can always add and remove partitions from all
2013 * devices. The needed partition minors are allocated from the
2014 * extended minor space, the main loop device numbers will continue
2015 * to match the loop minors, regardless of the number of partitions
2016 * used.
2017 *
2018 * If max_part is given, partition scanning is globally enabled for
2019 * all loop devices. The minors for the main loop devices will be
2020 * multiples of max_part.
2021 *
2022 * Note: Global-for-all-devices, set-only-at-init, read-only module
2023 * parameteters like 'max_loop' and 'max_part' make things needlessly
2024 * complicated, are too static, inflexible and may surprise
2025 * userspace tools. Parameters like this in general should be avoided.
2026 */
2027 if (!part_shift)
2028 set_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
2029 mutex_init(&lo->lo_mutex);
2030 lo->lo_number = i;
2031 spin_lock_init(&lo->lo_lock);
2032 spin_lock_init(&lo->lo_work_lock);
2033 INIT_WORK(&lo->rootcg_work, loop_rootcg_workfn);
2034 INIT_LIST_HEAD(&lo->rootcg_cmd_list);
2035 disk->major = LOOP_MAJOR;
2036 disk->first_minor = i << part_shift;
2037 disk->minors = 1 << part_shift;
2038 disk->fops = &lo_fops;
2039 disk->private_data = lo;
2040 disk->queue = lo->lo_queue;
2041 disk->events = DISK_EVENT_MEDIA_CHANGE;
2042 disk->event_flags = DISK_EVENT_FLAG_UEVENT;
2043 sprintf(disk->disk_name, "loop%d", i);
2044 /* Make this loop device reachable from pathname. */
2045 err = add_disk(disk);
2046 if (err)
2047 goto out_cleanup_disk;
2048
2049 /* Show this loop device. */
2050 mutex_lock(&loop_ctl_mutex);
2051 lo->idr_visible = true;
2052 mutex_unlock(&loop_ctl_mutex);
2053
2054 return i;
2055
2056out_cleanup_disk:
2057 put_disk(disk);
2058out_cleanup_tags:
2059 blk_mq_free_tag_set(&lo->tag_set);
2060out_free_idr:
2061 mutex_lock(&loop_ctl_mutex);
2062 idr_remove(&loop_index_idr, i);
2063 mutex_unlock(&loop_ctl_mutex);
2064out_free_dev:
2065 kfree(lo);
2066out:
2067 return err;
2068}
2069
2070static void loop_remove(struct loop_device *lo)
2071{
2072 /* Make this loop device unreachable from pathname. */
2073 del_gendisk(lo->lo_disk);
2074 blk_mq_free_tag_set(&lo->tag_set);
2075
2076 mutex_lock(&loop_ctl_mutex);
2077 idr_remove(&loop_index_idr, lo->lo_number);
2078 mutex_unlock(&loop_ctl_mutex);
2079
2080 put_disk(lo->lo_disk);
2081}
2082
2083static void loop_probe(dev_t dev)
2084{
2085 int idx = MINOR(dev) >> part_shift;
2086
2087 if (max_loop && idx >= max_loop)
2088 return;
2089 loop_add(idx);
2090}
2091
2092static int loop_control_remove(int idx)
2093{
2094 struct loop_device *lo;
2095 int ret;
2096
2097 if (idx < 0) {
2098 pr_warn_once("deleting an unspecified loop device is not supported.\n");
2099 return -EINVAL;
2100 }
2101
2102 /* Hide this loop device for serialization. */
2103 ret = mutex_lock_killable(&loop_ctl_mutex);
2104 if (ret)
2105 return ret;
2106 lo = idr_find(&loop_index_idr, idx);
2107 if (!lo || !lo->idr_visible)
2108 ret = -ENODEV;
2109 else
2110 lo->idr_visible = false;
2111 mutex_unlock(&loop_ctl_mutex);
2112 if (ret)
2113 return ret;
2114
2115 /* Check whether this loop device can be removed. */
2116 ret = mutex_lock_killable(&lo->lo_mutex);
2117 if (ret)
2118 goto mark_visible;
2119 if (lo->lo_state != Lo_unbound || disk_openers(lo->lo_disk) > 0) {
2120 mutex_unlock(&lo->lo_mutex);
2121 ret = -EBUSY;
2122 goto mark_visible;
2123 }
2124 /* Mark this loop device as no more bound, but not quite unbound yet */
2125 lo->lo_state = Lo_deleting;
2126 mutex_unlock(&lo->lo_mutex);
2127
2128 loop_remove(lo);
2129 return 0;
2130
2131mark_visible:
2132 /* Show this loop device again. */
2133 mutex_lock(&loop_ctl_mutex);
2134 lo->idr_visible = true;
2135 mutex_unlock(&loop_ctl_mutex);
2136 return ret;
2137}
2138
2139static int loop_control_get_free(int idx)
2140{
2141 struct loop_device *lo;
2142 int id, ret;
2143
2144 ret = mutex_lock_killable(&loop_ctl_mutex);
2145 if (ret)
2146 return ret;
2147 idr_for_each_entry(&loop_index_idr, lo, id) {
2148 /* Hitting a race results in creating a new loop device which is harmless. */
2149 if (lo->idr_visible && data_race(lo->lo_state) == Lo_unbound)
2150 goto found;
2151 }
2152 mutex_unlock(&loop_ctl_mutex);
2153 return loop_add(-1);
2154found:
2155 mutex_unlock(&loop_ctl_mutex);
2156 return id;
2157}
2158
2159static long loop_control_ioctl(struct file *file, unsigned int cmd,
2160 unsigned long parm)
2161{
2162 switch (cmd) {
2163 case LOOP_CTL_ADD:
2164 return loop_add(parm);
2165 case LOOP_CTL_REMOVE:
2166 return loop_control_remove(parm);
2167 case LOOP_CTL_GET_FREE:
2168 return loop_control_get_free(parm);
2169 default:
2170 return -ENOSYS;
2171 }
2172}
2173
2174static const struct file_operations loop_ctl_fops = {
2175 .open = nonseekable_open,
2176 .unlocked_ioctl = loop_control_ioctl,
2177 .compat_ioctl = loop_control_ioctl,
2178 .owner = THIS_MODULE,
2179 .llseek = noop_llseek,
2180};
2181
2182static struct miscdevice loop_misc = {
2183 .minor = LOOP_CTRL_MINOR,
2184 .name = "loop-control",
2185 .fops = &loop_ctl_fops,
2186};
2187
2188MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
2189MODULE_ALIAS("devname:loop-control");
2190
2191static int __init loop_init(void)
2192{
2193 int i;
2194 int err;
2195
2196 part_shift = 0;
2197 if (max_part > 0) {
2198 part_shift = fls(max_part);
2199
2200 /*
2201 * Adjust max_part according to part_shift as it is exported
2202 * to user space so that user can decide correct minor number
2203 * if [s]he want to create more devices.
2204 *
2205 * Note that -1 is required because partition 0 is reserved
2206 * for the whole disk.
2207 */
2208 max_part = (1UL << part_shift) - 1;
2209 }
2210
2211 if ((1UL << part_shift) > DISK_MAX_PARTS) {
2212 err = -EINVAL;
2213 goto err_out;
2214 }
2215
2216 if (max_loop > 1UL << (MINORBITS - part_shift)) {
2217 err = -EINVAL;
2218 goto err_out;
2219 }
2220
2221 err = misc_register(&loop_misc);
2222 if (err < 0)
2223 goto err_out;
2224
2225
2226 if (__register_blkdev(LOOP_MAJOR, "loop", loop_probe)) {
2227 err = -EIO;
2228 goto misc_out;
2229 }
2230
2231 /* pre-create number of devices given by config or max_loop */
2232 for (i = 0; i < max_loop; i++)
2233 loop_add(i);
2234
2235 printk(KERN_INFO "loop: module loaded\n");
2236 return 0;
2237
2238misc_out:
2239 misc_deregister(&loop_misc);
2240err_out:
2241 return err;
2242}
2243
2244static void __exit loop_exit(void)
2245{
2246 struct loop_device *lo;
2247 int id;
2248
2249 unregister_blkdev(LOOP_MAJOR, "loop");
2250 misc_deregister(&loop_misc);
2251
2252 /*
2253 * There is no need to use loop_ctl_mutex here, for nobody else can
2254 * access loop_index_idr when this module is unloading (unless forced
2255 * module unloading is requested). If this is not a clean unloading,
2256 * we have no means to avoid kernel crash.
2257 */
2258 idr_for_each_entry(&loop_index_idr, lo, id)
2259 loop_remove(lo);
2260
2261 idr_destroy(&loop_index_idr);
2262}
2263
2264module_init(loop_init);
2265module_exit(loop_exit);
2266
2267#ifndef MODULE
2268static int __init max_loop_setup(char *str)
2269{
2270 max_loop = simple_strtol(str, NULL, 0);
2271 return 1;
2272}
2273
2274__setup("max_loop=", max_loop_setup);
2275#endif