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1/*
2 * linux/drivers/block/loop.c
3 *
4 * Written by Theodore Ts'o, 3/29/93
5 *
6 * Copyright 1993 by Theodore Ts'o. Redistribution of this file is
7 * permitted under the GNU General Public License.
8 *
9 * DES encryption plus some minor changes by Werner Almesberger, 30-MAY-1993
10 * more DES encryption plus IDEA encryption by Nicholas J. Leon, June 20, 1996
11 *
12 * Modularized and updated for 1.1.16 kernel - Mitch Dsouza 28th May 1994
13 * Adapted for 1.3.59 kernel - Andries Brouwer, 1 Feb 1996
14 *
15 * Fixed do_loop_request() re-entrancy - Vincent.Renardias@waw.com Mar 20, 1997
16 *
17 * Added devfs support - Richard Gooch <rgooch@atnf.csiro.au> 16-Jan-1998
18 *
19 * Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998
20 *
21 * Loadable modules and other fixes by AK, 1998
22 *
23 * Make real block number available to downstream transfer functions, enables
24 * CBC (and relatives) mode encryption requiring unique IVs per data block.
25 * Reed H. Petty, rhp@draper.net
26 *
27 * Maximum number of loop devices now dynamic via max_loop module parameter.
28 * Russell Kroll <rkroll@exploits.org> 19990701
29 *
30 * Maximum number of loop devices when compiled-in now selectable by passing
31 * max_loop=<1-255> to the kernel on boot.
32 * Erik I. Bolsø, <eriki@himolde.no>, Oct 31, 1999
33 *
34 * Completely rewrite request handling to be make_request_fn style and
35 * non blocking, pushing work to a helper thread. Lots of fixes from
36 * Al Viro too.
37 * Jens Axboe <axboe@suse.de>, Nov 2000
38 *
39 * Support up to 256 loop devices
40 * Heinz Mauelshagen <mge@sistina.com>, Feb 2002
41 *
42 * Support for falling back on the write file operation when the address space
43 * operations write_begin is not available on the backing filesystem.
44 * Anton Altaparmakov, 16 Feb 2005
45 *
46 * Still To Fix:
47 * - Advisory locking is ignored here.
48 * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
49 *
50 */
51
52#include <linux/module.h>
53#include <linux/moduleparam.h>
54#include <linux/sched.h>
55#include <linux/fs.h>
56#include <linux/file.h>
57#include <linux/stat.h>
58#include <linux/errno.h>
59#include <linux/major.h>
60#include <linux/wait.h>
61#include <linux/blkdev.h>
62#include <linux/blkpg.h>
63#include <linux/init.h>
64#include <linux/swap.h>
65#include <linux/slab.h>
66#include <linux/compat.h>
67#include <linux/suspend.h>
68#include <linux/freezer.h>
69#include <linux/mutex.h>
70#include <linux/writeback.h>
71#include <linux/completion.h>
72#include <linux/highmem.h>
73#include <linux/kthread.h>
74#include <linux/splice.h>
75#include <linux/sysfs.h>
76#include <linux/miscdevice.h>
77#include <linux/falloc.h>
78#include "loop.h"
79
80#include <asm/uaccess.h>
81
82static DEFINE_IDR(loop_index_idr);
83static DEFINE_MUTEX(loop_index_mutex);
84
85static int max_part;
86static int part_shift;
87
88/*
89 * Transfer functions
90 */
91static int transfer_none(struct loop_device *lo, int cmd,
92 struct page *raw_page, unsigned raw_off,
93 struct page *loop_page, unsigned loop_off,
94 int size, sector_t real_block)
95{
96 char *raw_buf = kmap_atomic(raw_page) + raw_off;
97 char *loop_buf = kmap_atomic(loop_page) + loop_off;
98
99 if (cmd == READ)
100 memcpy(loop_buf, raw_buf, size);
101 else
102 memcpy(raw_buf, loop_buf, size);
103
104 kunmap_atomic(loop_buf);
105 kunmap_atomic(raw_buf);
106 cond_resched();
107 return 0;
108}
109
110static int transfer_xor(struct loop_device *lo, int cmd,
111 struct page *raw_page, unsigned raw_off,
112 struct page *loop_page, unsigned loop_off,
113 int size, sector_t real_block)
114{
115 char *raw_buf = kmap_atomic(raw_page) + raw_off;
116 char *loop_buf = kmap_atomic(loop_page) + loop_off;
117 char *in, *out, *key;
118 int i, keysize;
119
120 if (cmd == READ) {
121 in = raw_buf;
122 out = loop_buf;
123 } else {
124 in = loop_buf;
125 out = raw_buf;
126 }
127
128 key = lo->lo_encrypt_key;
129 keysize = lo->lo_encrypt_key_size;
130 for (i = 0; i < size; i++)
131 *out++ = *in++ ^ key[(i & 511) % keysize];
132
133 kunmap_atomic(loop_buf);
134 kunmap_atomic(raw_buf);
135 cond_resched();
136 return 0;
137}
138
139static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
140{
141 if (unlikely(info->lo_encrypt_key_size <= 0))
142 return -EINVAL;
143 return 0;
144}
145
146static struct loop_func_table none_funcs = {
147 .number = LO_CRYPT_NONE,
148 .transfer = transfer_none,
149};
150
151static struct loop_func_table xor_funcs = {
152 .number = LO_CRYPT_XOR,
153 .transfer = transfer_xor,
154 .init = xor_init
155};
156
157/* xfer_funcs[0] is special - its release function is never called */
158static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
159 &none_funcs,
160 &xor_funcs
161};
162
163static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
164{
165 loff_t loopsize;
166
167 /* Compute loopsize in bytes */
168 loopsize = i_size_read(file->f_mapping->host);
169 if (offset > 0)
170 loopsize -= offset;
171 /* offset is beyond i_size, weird but possible */
172 if (loopsize < 0)
173 return 0;
174
175 if (sizelimit > 0 && sizelimit < loopsize)
176 loopsize = sizelimit;
177 /*
178 * Unfortunately, if we want to do I/O on the device,
179 * the number of 512-byte sectors has to fit into a sector_t.
180 */
181 return loopsize >> 9;
182}
183
184static loff_t get_loop_size(struct loop_device *lo, struct file *file)
185{
186 return get_size(lo->lo_offset, lo->lo_sizelimit, file);
187}
188
189static int
190figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
191{
192 loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
193 sector_t x = (sector_t)size;
194 struct block_device *bdev = lo->lo_device;
195
196 if (unlikely((loff_t)x != size))
197 return -EFBIG;
198 if (lo->lo_offset != offset)
199 lo->lo_offset = offset;
200 if (lo->lo_sizelimit != sizelimit)
201 lo->lo_sizelimit = sizelimit;
202 set_capacity(lo->lo_disk, x);
203 bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
204 /* let user-space know about the new size */
205 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
206 return 0;
207}
208
209static inline int
210lo_do_transfer(struct loop_device *lo, int cmd,
211 struct page *rpage, unsigned roffs,
212 struct page *lpage, unsigned loffs,
213 int size, sector_t rblock)
214{
215 if (unlikely(!lo->transfer))
216 return 0;
217
218 return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
219}
220
221/**
222 * __do_lo_send_write - helper for writing data to a loop device
223 *
224 * This helper just factors out common code between do_lo_send_direct_write()
225 * and do_lo_send_write().
226 */
227static int __do_lo_send_write(struct file *file,
228 u8 *buf, const int len, loff_t pos)
229{
230 ssize_t bw;
231 mm_segment_t old_fs = get_fs();
232
233 file_start_write(file);
234 set_fs(get_ds());
235 bw = file->f_op->write(file, buf, len, &pos);
236 set_fs(old_fs);
237 file_end_write(file);
238 if (likely(bw == len))
239 return 0;
240 printk_ratelimited(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
241 (unsigned long long)pos, len);
242 if (bw >= 0)
243 bw = -EIO;
244 return bw;
245}
246
247/**
248 * do_lo_send_direct_write - helper for writing data to a loop device
249 *
250 * This is the fast, non-transforming version that does not need double
251 * buffering.
252 */
253static int do_lo_send_direct_write(struct loop_device *lo,
254 struct bio_vec *bvec, loff_t pos, struct page *page)
255{
256 ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
257 kmap(bvec->bv_page) + bvec->bv_offset,
258 bvec->bv_len, pos);
259 kunmap(bvec->bv_page);
260 cond_resched();
261 return bw;
262}
263
264/**
265 * do_lo_send_write - helper for writing data to a loop device
266 *
267 * This is the slow, transforming version that needs to double buffer the
268 * data as it cannot do the transformations in place without having direct
269 * access to the destination pages of the backing file.
270 */
271static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
272 loff_t pos, struct page *page)
273{
274 int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
275 bvec->bv_offset, bvec->bv_len, pos >> 9);
276 if (likely(!ret))
277 return __do_lo_send_write(lo->lo_backing_file,
278 page_address(page), bvec->bv_len,
279 pos);
280 printk_ratelimited(KERN_ERR "loop: Transfer error at byte offset %llu, "
281 "length %i.\n", (unsigned long long)pos, bvec->bv_len);
282 if (ret > 0)
283 ret = -EIO;
284 return ret;
285}
286
287static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos)
288{
289 int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t,
290 struct page *page);
291 struct bio_vec bvec;
292 struct bvec_iter iter;
293 struct page *page = NULL;
294 int ret = 0;
295
296 if (lo->transfer != transfer_none) {
297 page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
298 if (unlikely(!page))
299 goto fail;
300 kmap(page);
301 do_lo_send = do_lo_send_write;
302 } else {
303 do_lo_send = do_lo_send_direct_write;
304 }
305
306 bio_for_each_segment(bvec, bio, iter) {
307 ret = do_lo_send(lo, &bvec, pos, page);
308 if (ret < 0)
309 break;
310 pos += bvec.bv_len;
311 }
312 if (page) {
313 kunmap(page);
314 __free_page(page);
315 }
316out:
317 return ret;
318fail:
319 printk_ratelimited(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
320 ret = -ENOMEM;
321 goto out;
322}
323
324struct lo_read_data {
325 struct loop_device *lo;
326 struct page *page;
327 unsigned offset;
328 int bsize;
329};
330
331static int
332lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
333 struct splice_desc *sd)
334{
335 struct lo_read_data *p = sd->u.data;
336 struct loop_device *lo = p->lo;
337 struct page *page = buf->page;
338 sector_t IV;
339 int size;
340
341 IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) +
342 (buf->offset >> 9);
343 size = sd->len;
344 if (size > p->bsize)
345 size = p->bsize;
346
347 if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) {
348 printk_ratelimited(KERN_ERR "loop: transfer error block %ld\n",
349 page->index);
350 size = -EINVAL;
351 }
352
353 flush_dcache_page(p->page);
354
355 if (size > 0)
356 p->offset += size;
357
358 return size;
359}
360
361static int
362lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd)
363{
364 return __splice_from_pipe(pipe, sd, lo_splice_actor);
365}
366
367static ssize_t
368do_lo_receive(struct loop_device *lo,
369 struct bio_vec *bvec, int bsize, loff_t pos)
370{
371 struct lo_read_data cookie;
372 struct splice_desc sd;
373 struct file *file;
374 ssize_t retval;
375
376 cookie.lo = lo;
377 cookie.page = bvec->bv_page;
378 cookie.offset = bvec->bv_offset;
379 cookie.bsize = bsize;
380
381 sd.len = 0;
382 sd.total_len = bvec->bv_len;
383 sd.flags = 0;
384 sd.pos = pos;
385 sd.u.data = &cookie;
386
387 file = lo->lo_backing_file;
388 retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);
389
390 return retval;
391}
392
393static int
394lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos)
395{
396 struct bio_vec bvec;
397 struct bvec_iter iter;
398 ssize_t s;
399
400 bio_for_each_segment(bvec, bio, iter) {
401 s = do_lo_receive(lo, &bvec, bsize, pos);
402 if (s < 0)
403 return s;
404
405 if (s != bvec.bv_len) {
406 zero_fill_bio(bio);
407 break;
408 }
409 pos += bvec.bv_len;
410 }
411 return 0;
412}
413
414static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
415{
416 loff_t pos;
417 int ret;
418
419 pos = ((loff_t) bio->bi_iter.bi_sector << 9) + lo->lo_offset;
420
421 if (bio_rw(bio) == WRITE) {
422 struct file *file = lo->lo_backing_file;
423
424 if (bio->bi_rw & REQ_FLUSH) {
425 ret = vfs_fsync(file, 0);
426 if (unlikely(ret && ret != -EINVAL)) {
427 ret = -EIO;
428 goto out;
429 }
430 }
431
432 /*
433 * We use punch hole to reclaim the free space used by the
434 * image a.k.a. discard. However we do not support discard if
435 * encryption is enabled, because it may give an attacker
436 * useful information.
437 */
438 if (bio->bi_rw & REQ_DISCARD) {
439 struct file *file = lo->lo_backing_file;
440 int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
441
442 if ((!file->f_op->fallocate) ||
443 lo->lo_encrypt_key_size) {
444 ret = -EOPNOTSUPP;
445 goto out;
446 }
447 ret = file->f_op->fallocate(file, mode, pos,
448 bio->bi_iter.bi_size);
449 if (unlikely(ret && ret != -EINVAL &&
450 ret != -EOPNOTSUPP))
451 ret = -EIO;
452 goto out;
453 }
454
455 ret = lo_send(lo, bio, pos);
456
457 if ((bio->bi_rw & REQ_FUA) && !ret) {
458 ret = vfs_fsync(file, 0);
459 if (unlikely(ret && ret != -EINVAL))
460 ret = -EIO;
461 }
462 } else
463 ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
464
465out:
466 return ret;
467}
468
469/*
470 * Add bio to back of pending list
471 */
472static void loop_add_bio(struct loop_device *lo, struct bio *bio)
473{
474 lo->lo_bio_count++;
475 bio_list_add(&lo->lo_bio_list, bio);
476}
477
478/*
479 * Grab first pending buffer
480 */
481static struct bio *loop_get_bio(struct loop_device *lo)
482{
483 lo->lo_bio_count--;
484 return bio_list_pop(&lo->lo_bio_list);
485}
486
487static void loop_make_request(struct request_queue *q, struct bio *old_bio)
488{
489 struct loop_device *lo = q->queuedata;
490 int rw = bio_rw(old_bio);
491
492 if (rw == READA)
493 rw = READ;
494
495 BUG_ON(!lo || (rw != READ && rw != WRITE));
496
497 spin_lock_irq(&lo->lo_lock);
498 if (lo->lo_state != Lo_bound)
499 goto out;
500 if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))
501 goto out;
502 if (lo->lo_bio_count >= q->nr_congestion_on)
503 wait_event_lock_irq(lo->lo_req_wait,
504 lo->lo_bio_count < q->nr_congestion_off,
505 lo->lo_lock);
506 loop_add_bio(lo, old_bio);
507 wake_up(&lo->lo_event);
508 spin_unlock_irq(&lo->lo_lock);
509 return;
510
511out:
512 spin_unlock_irq(&lo->lo_lock);
513 bio_io_error(old_bio);
514}
515
516struct switch_request {
517 struct file *file;
518 struct completion wait;
519};
520
521static void do_loop_switch(struct loop_device *, struct switch_request *);
522
523static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio)
524{
525 if (unlikely(!bio->bi_bdev)) {
526 do_loop_switch(lo, bio->bi_private);
527 bio_put(bio);
528 } else {
529 int ret = do_bio_filebacked(lo, bio);
530 bio_endio(bio, ret);
531 }
532}
533
534/*
535 * worker thread that handles reads/writes to file backed loop devices,
536 * to avoid blocking in our make_request_fn. it also does loop decrypting
537 * on reads for block backed loop, as that is too heavy to do from
538 * b_end_io context where irqs may be disabled.
539 *
540 * Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before
541 * calling kthread_stop(). Therefore once kthread_should_stop() is
542 * true, make_request will not place any more requests. Therefore
543 * once kthread_should_stop() is true and lo_bio is NULL, we are
544 * done with the loop.
545 */
546static int loop_thread(void *data)
547{
548 struct loop_device *lo = data;
549 struct bio *bio;
550
551 set_user_nice(current, -20);
552
553 while (!kthread_should_stop() || !bio_list_empty(&lo->lo_bio_list)) {
554
555 wait_event_interruptible(lo->lo_event,
556 !bio_list_empty(&lo->lo_bio_list) ||
557 kthread_should_stop());
558
559 if (bio_list_empty(&lo->lo_bio_list))
560 continue;
561 spin_lock_irq(&lo->lo_lock);
562 bio = loop_get_bio(lo);
563 if (lo->lo_bio_count < lo->lo_queue->nr_congestion_off)
564 wake_up(&lo->lo_req_wait);
565 spin_unlock_irq(&lo->lo_lock);
566
567 BUG_ON(!bio);
568 loop_handle_bio(lo, bio);
569 }
570
571 return 0;
572}
573
574/*
575 * loop_switch performs the hard work of switching a backing store.
576 * First it needs to flush existing IO, it does this by sending a magic
577 * BIO down the pipe. The completion of this BIO does the actual switch.
578 */
579static int loop_switch(struct loop_device *lo, struct file *file)
580{
581 struct switch_request w;
582 struct bio *bio = bio_alloc(GFP_KERNEL, 0);
583 if (!bio)
584 return -ENOMEM;
585 init_completion(&w.wait);
586 w.file = file;
587 bio->bi_private = &w;
588 bio->bi_bdev = NULL;
589 loop_make_request(lo->lo_queue, bio);
590 wait_for_completion(&w.wait);
591 return 0;
592}
593
594/*
595 * Helper to flush the IOs in loop, but keeping loop thread running
596 */
597static int loop_flush(struct loop_device *lo)
598{
599 /* loop not yet configured, no running thread, nothing to flush */
600 if (!lo->lo_thread)
601 return 0;
602
603 return loop_switch(lo, NULL);
604}
605
606/*
607 * Do the actual switch; called from the BIO completion routine
608 */
609static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
610{
611 struct file *file = p->file;
612 struct file *old_file = lo->lo_backing_file;
613 struct address_space *mapping;
614
615 /* if no new file, only flush of queued bios requested */
616 if (!file)
617 goto out;
618
619 mapping = file->f_mapping;
620 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
621 lo->lo_backing_file = file;
622 lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
623 mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
624 lo->old_gfp_mask = mapping_gfp_mask(mapping);
625 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
626out:
627 complete(&p->wait);
628}
629
630
631/*
632 * loop_change_fd switched the backing store of a loopback device to
633 * a new file. This is useful for operating system installers to free up
634 * the original file and in High Availability environments to switch to
635 * an alternative location for the content in case of server meltdown.
636 * This can only work if the loop device is used read-only, and if the
637 * new backing store is the same size and type as the old backing store.
638 */
639static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
640 unsigned int arg)
641{
642 struct file *file, *old_file;
643 struct inode *inode;
644 int error;
645
646 error = -ENXIO;
647 if (lo->lo_state != Lo_bound)
648 goto out;
649
650 /* the loop device has to be read-only */
651 error = -EINVAL;
652 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
653 goto out;
654
655 error = -EBADF;
656 file = fget(arg);
657 if (!file)
658 goto out;
659
660 inode = file->f_mapping->host;
661 old_file = lo->lo_backing_file;
662
663 error = -EINVAL;
664
665 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
666 goto out_putf;
667
668 /* size of the new backing store needs to be the same */
669 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
670 goto out_putf;
671
672 /* and ... switch */
673 error = loop_switch(lo, file);
674 if (error)
675 goto out_putf;
676
677 fput(old_file);
678 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
679 ioctl_by_bdev(bdev, BLKRRPART, 0);
680 return 0;
681
682 out_putf:
683 fput(file);
684 out:
685 return error;
686}
687
688static inline int is_loop_device(struct file *file)
689{
690 struct inode *i = file->f_mapping->host;
691
692 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
693}
694
695/* loop sysfs attributes */
696
697static ssize_t loop_attr_show(struct device *dev, char *page,
698 ssize_t (*callback)(struct loop_device *, char *))
699{
700 struct gendisk *disk = dev_to_disk(dev);
701 struct loop_device *lo = disk->private_data;
702
703 return callback(lo, page);
704}
705
706#define LOOP_ATTR_RO(_name) \
707static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
708static ssize_t loop_attr_do_show_##_name(struct device *d, \
709 struct device_attribute *attr, char *b) \
710{ \
711 return loop_attr_show(d, b, loop_attr_##_name##_show); \
712} \
713static struct device_attribute loop_attr_##_name = \
714 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
715
716static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
717{
718 ssize_t ret;
719 char *p = NULL;
720
721 spin_lock_irq(&lo->lo_lock);
722 if (lo->lo_backing_file)
723 p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1);
724 spin_unlock_irq(&lo->lo_lock);
725
726 if (IS_ERR_OR_NULL(p))
727 ret = PTR_ERR(p);
728 else {
729 ret = strlen(p);
730 memmove(buf, p, ret);
731 buf[ret++] = '\n';
732 buf[ret] = 0;
733 }
734
735 return ret;
736}
737
738static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
739{
740 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
741}
742
743static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
744{
745 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
746}
747
748static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
749{
750 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
751
752 return sprintf(buf, "%s\n", autoclear ? "1" : "0");
753}
754
755static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
756{
757 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
758
759 return sprintf(buf, "%s\n", partscan ? "1" : "0");
760}
761
762LOOP_ATTR_RO(backing_file);
763LOOP_ATTR_RO(offset);
764LOOP_ATTR_RO(sizelimit);
765LOOP_ATTR_RO(autoclear);
766LOOP_ATTR_RO(partscan);
767
768static struct attribute *loop_attrs[] = {
769 &loop_attr_backing_file.attr,
770 &loop_attr_offset.attr,
771 &loop_attr_sizelimit.attr,
772 &loop_attr_autoclear.attr,
773 &loop_attr_partscan.attr,
774 NULL,
775};
776
777static struct attribute_group loop_attribute_group = {
778 .name = "loop",
779 .attrs= loop_attrs,
780};
781
782static int loop_sysfs_init(struct loop_device *lo)
783{
784 return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
785 &loop_attribute_group);
786}
787
788static void loop_sysfs_exit(struct loop_device *lo)
789{
790 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
791 &loop_attribute_group);
792}
793
794static void loop_config_discard(struct loop_device *lo)
795{
796 struct file *file = lo->lo_backing_file;
797 struct inode *inode = file->f_mapping->host;
798 struct request_queue *q = lo->lo_queue;
799
800 /*
801 * We use punch hole to reclaim the free space used by the
802 * image a.k.a. discard. However we do not support discard if
803 * encryption is enabled, because it may give an attacker
804 * useful information.
805 */
806 if ((!file->f_op->fallocate) ||
807 lo->lo_encrypt_key_size) {
808 q->limits.discard_granularity = 0;
809 q->limits.discard_alignment = 0;
810 q->limits.max_discard_sectors = 0;
811 q->limits.discard_zeroes_data = 0;
812 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
813 return;
814 }
815
816 q->limits.discard_granularity = inode->i_sb->s_blocksize;
817 q->limits.discard_alignment = 0;
818 q->limits.max_discard_sectors = UINT_MAX >> 9;
819 q->limits.discard_zeroes_data = 1;
820 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
821}
822
823static int loop_set_fd(struct loop_device *lo, fmode_t mode,
824 struct block_device *bdev, unsigned int arg)
825{
826 struct file *file, *f;
827 struct inode *inode;
828 struct address_space *mapping;
829 unsigned lo_blocksize;
830 int lo_flags = 0;
831 int error;
832 loff_t size;
833
834 /* This is safe, since we have a reference from open(). */
835 __module_get(THIS_MODULE);
836
837 error = -EBADF;
838 file = fget(arg);
839 if (!file)
840 goto out;
841
842 error = -EBUSY;
843 if (lo->lo_state != Lo_unbound)
844 goto out_putf;
845
846 /* Avoid recursion */
847 f = file;
848 while (is_loop_device(f)) {
849 struct loop_device *l;
850
851 if (f->f_mapping->host->i_bdev == bdev)
852 goto out_putf;
853
854 l = f->f_mapping->host->i_bdev->bd_disk->private_data;
855 if (l->lo_state == Lo_unbound) {
856 error = -EINVAL;
857 goto out_putf;
858 }
859 f = l->lo_backing_file;
860 }
861
862 mapping = file->f_mapping;
863 inode = mapping->host;
864
865 error = -EINVAL;
866 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
867 goto out_putf;
868
869 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
870 !file->f_op->write)
871 lo_flags |= LO_FLAGS_READ_ONLY;
872
873 lo_blocksize = S_ISBLK(inode->i_mode) ?
874 inode->i_bdev->bd_block_size : PAGE_SIZE;
875
876 error = -EFBIG;
877 size = get_loop_size(lo, file);
878 if ((loff_t)(sector_t)size != size)
879 goto out_putf;
880
881 error = 0;
882
883 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
884
885 lo->lo_blocksize = lo_blocksize;
886 lo->lo_device = bdev;
887 lo->lo_flags = lo_flags;
888 lo->lo_backing_file = file;
889 lo->transfer = transfer_none;
890 lo->ioctl = NULL;
891 lo->lo_sizelimit = 0;
892 lo->lo_bio_count = 0;
893 lo->old_gfp_mask = mapping_gfp_mask(mapping);
894 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
895
896 bio_list_init(&lo->lo_bio_list);
897
898 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
899 blk_queue_flush(lo->lo_queue, REQ_FLUSH);
900
901 set_capacity(lo->lo_disk, size);
902 bd_set_size(bdev, size << 9);
903 loop_sysfs_init(lo);
904 /* let user-space know about the new size */
905 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
906
907 set_blocksize(bdev, lo_blocksize);
908
909 lo->lo_thread = kthread_create(loop_thread, lo, "loop%d",
910 lo->lo_number);
911 if (IS_ERR(lo->lo_thread)) {
912 error = PTR_ERR(lo->lo_thread);
913 goto out_clr;
914 }
915 lo->lo_state = Lo_bound;
916 wake_up_process(lo->lo_thread);
917 if (part_shift)
918 lo->lo_flags |= LO_FLAGS_PARTSCAN;
919 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
920 ioctl_by_bdev(bdev, BLKRRPART, 0);
921
922 /* Grab the block_device to prevent its destruction after we
923 * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev).
924 */
925 bdgrab(bdev);
926 return 0;
927
928out_clr:
929 loop_sysfs_exit(lo);
930 lo->lo_thread = NULL;
931 lo->lo_device = NULL;
932 lo->lo_backing_file = NULL;
933 lo->lo_flags = 0;
934 set_capacity(lo->lo_disk, 0);
935 invalidate_bdev(bdev);
936 bd_set_size(bdev, 0);
937 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
938 mapping_set_gfp_mask(mapping, lo->old_gfp_mask);
939 lo->lo_state = Lo_unbound;
940 out_putf:
941 fput(file);
942 out:
943 /* This is safe: open() is still holding a reference. */
944 module_put(THIS_MODULE);
945 return error;
946}
947
948static int
949loop_release_xfer(struct loop_device *lo)
950{
951 int err = 0;
952 struct loop_func_table *xfer = lo->lo_encryption;
953
954 if (xfer) {
955 if (xfer->release)
956 err = xfer->release(lo);
957 lo->transfer = NULL;
958 lo->lo_encryption = NULL;
959 module_put(xfer->owner);
960 }
961 return err;
962}
963
964static int
965loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
966 const struct loop_info64 *i)
967{
968 int err = 0;
969
970 if (xfer) {
971 struct module *owner = xfer->owner;
972
973 if (!try_module_get(owner))
974 return -EINVAL;
975 if (xfer->init)
976 err = xfer->init(lo, i);
977 if (err)
978 module_put(owner);
979 else
980 lo->lo_encryption = xfer;
981 }
982 return err;
983}
984
985static int loop_clr_fd(struct loop_device *lo)
986{
987 struct file *filp = lo->lo_backing_file;
988 gfp_t gfp = lo->old_gfp_mask;
989 struct block_device *bdev = lo->lo_device;
990
991 if (lo->lo_state != Lo_bound)
992 return -ENXIO;
993
994 /*
995 * If we've explicitly asked to tear down the loop device,
996 * and it has an elevated reference count, set it for auto-teardown when
997 * the last reference goes away. This stops $!~#$@ udev from
998 * preventing teardown because it decided that it needs to run blkid on
999 * the loopback device whenever they appear. xfstests is notorious for
1000 * failing tests because blkid via udev races with a losetup
1001 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
1002 * command to fail with EBUSY.
1003 */
1004 if (lo->lo_refcnt > 1) {
1005 lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
1006 mutex_unlock(&lo->lo_ctl_mutex);
1007 return 0;
1008 }
1009
1010 if (filp == NULL)
1011 return -EINVAL;
1012
1013 spin_lock_irq(&lo->lo_lock);
1014 lo->lo_state = Lo_rundown;
1015 spin_unlock_irq(&lo->lo_lock);
1016
1017 kthread_stop(lo->lo_thread);
1018
1019 spin_lock_irq(&lo->lo_lock);
1020 lo->lo_backing_file = NULL;
1021 spin_unlock_irq(&lo->lo_lock);
1022
1023 loop_release_xfer(lo);
1024 lo->transfer = NULL;
1025 lo->ioctl = NULL;
1026 lo->lo_device = NULL;
1027 lo->lo_encryption = NULL;
1028 lo->lo_offset = 0;
1029 lo->lo_sizelimit = 0;
1030 lo->lo_encrypt_key_size = 0;
1031 lo->lo_thread = NULL;
1032 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
1033 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
1034 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1035 if (bdev) {
1036 bdput(bdev);
1037 invalidate_bdev(bdev);
1038 }
1039 set_capacity(lo->lo_disk, 0);
1040 loop_sysfs_exit(lo);
1041 if (bdev) {
1042 bd_set_size(bdev, 0);
1043 /* let user-space know about this change */
1044 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1045 }
1046 mapping_set_gfp_mask(filp->f_mapping, gfp);
1047 lo->lo_state = Lo_unbound;
1048 /* This is safe: open() is still holding a reference. */
1049 module_put(THIS_MODULE);
1050 if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
1051 ioctl_by_bdev(bdev, BLKRRPART, 0);
1052 lo->lo_flags = 0;
1053 if (!part_shift)
1054 lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
1055 mutex_unlock(&lo->lo_ctl_mutex);
1056 /*
1057 * Need not hold lo_ctl_mutex to fput backing file.
1058 * Calling fput holding lo_ctl_mutex triggers a circular
1059 * lock dependency possibility warning as fput can take
1060 * bd_mutex which is usually taken before lo_ctl_mutex.
1061 */
1062 fput(filp);
1063 return 0;
1064}
1065
1066static int
1067loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1068{
1069 int err;
1070 struct loop_func_table *xfer;
1071 kuid_t uid = current_uid();
1072
1073 if (lo->lo_encrypt_key_size &&
1074 !uid_eq(lo->lo_key_owner, uid) &&
1075 !capable(CAP_SYS_ADMIN))
1076 return -EPERM;
1077 if (lo->lo_state != Lo_bound)
1078 return -ENXIO;
1079 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
1080 return -EINVAL;
1081
1082 err = loop_release_xfer(lo);
1083 if (err)
1084 return err;
1085
1086 if (info->lo_encrypt_type) {
1087 unsigned int type = info->lo_encrypt_type;
1088
1089 if (type >= MAX_LO_CRYPT)
1090 return -EINVAL;
1091 xfer = xfer_funcs[type];
1092 if (xfer == NULL)
1093 return -EINVAL;
1094 } else
1095 xfer = NULL;
1096
1097 err = loop_init_xfer(lo, xfer, info);
1098 if (err)
1099 return err;
1100
1101 if (lo->lo_offset != info->lo_offset ||
1102 lo->lo_sizelimit != info->lo_sizelimit)
1103 if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
1104 return -EFBIG;
1105
1106 loop_config_discard(lo);
1107
1108 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
1109 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
1110 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
1111 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
1112
1113 if (!xfer)
1114 xfer = &none_funcs;
1115 lo->transfer = xfer->transfer;
1116 lo->ioctl = xfer->ioctl;
1117
1118 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
1119 (info->lo_flags & LO_FLAGS_AUTOCLEAR))
1120 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
1121
1122 if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&
1123 !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
1124 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1125 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
1126 ioctl_by_bdev(lo->lo_device, BLKRRPART, 0);
1127 }
1128
1129 lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
1130 lo->lo_init[0] = info->lo_init[0];
1131 lo->lo_init[1] = info->lo_init[1];
1132 if (info->lo_encrypt_key_size) {
1133 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
1134 info->lo_encrypt_key_size);
1135 lo->lo_key_owner = uid;
1136 }
1137
1138 return 0;
1139}
1140
1141static int
1142loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1143{
1144 struct file *file = lo->lo_backing_file;
1145 struct kstat stat;
1146 int error;
1147
1148 if (lo->lo_state != Lo_bound)
1149 return -ENXIO;
1150 error = vfs_getattr(&file->f_path, &stat);
1151 if (error)
1152 return error;
1153 memset(info, 0, sizeof(*info));
1154 info->lo_number = lo->lo_number;
1155 info->lo_device = huge_encode_dev(stat.dev);
1156 info->lo_inode = stat.ino;
1157 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
1158 info->lo_offset = lo->lo_offset;
1159 info->lo_sizelimit = lo->lo_sizelimit;
1160 info->lo_flags = lo->lo_flags;
1161 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1162 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1163 info->lo_encrypt_type =
1164 lo->lo_encryption ? lo->lo_encryption->number : 0;
1165 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1166 info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1167 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1168 lo->lo_encrypt_key_size);
1169 }
1170 return 0;
1171}
1172
1173static void
1174loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1175{
1176 memset(info64, 0, sizeof(*info64));
1177 info64->lo_number = info->lo_number;
1178 info64->lo_device = info->lo_device;
1179 info64->lo_inode = info->lo_inode;
1180 info64->lo_rdevice = info->lo_rdevice;
1181 info64->lo_offset = info->lo_offset;
1182 info64->lo_sizelimit = 0;
1183 info64->lo_encrypt_type = info->lo_encrypt_type;
1184 info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1185 info64->lo_flags = info->lo_flags;
1186 info64->lo_init[0] = info->lo_init[0];
1187 info64->lo_init[1] = info->lo_init[1];
1188 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1189 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1190 else
1191 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1192 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1193}
1194
1195static int
1196loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1197{
1198 memset(info, 0, sizeof(*info));
1199 info->lo_number = info64->lo_number;
1200 info->lo_device = info64->lo_device;
1201 info->lo_inode = info64->lo_inode;
1202 info->lo_rdevice = info64->lo_rdevice;
1203 info->lo_offset = info64->lo_offset;
1204 info->lo_encrypt_type = info64->lo_encrypt_type;
1205 info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1206 info->lo_flags = info64->lo_flags;
1207 info->lo_init[0] = info64->lo_init[0];
1208 info->lo_init[1] = info64->lo_init[1];
1209 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1210 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1211 else
1212 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1213 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1214
1215 /* error in case values were truncated */
1216 if (info->lo_device != info64->lo_device ||
1217 info->lo_rdevice != info64->lo_rdevice ||
1218 info->lo_inode != info64->lo_inode ||
1219 info->lo_offset != info64->lo_offset)
1220 return -EOVERFLOW;
1221
1222 return 0;
1223}
1224
1225static int
1226loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1227{
1228 struct loop_info info;
1229 struct loop_info64 info64;
1230
1231 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1232 return -EFAULT;
1233 loop_info64_from_old(&info, &info64);
1234 return loop_set_status(lo, &info64);
1235}
1236
1237static int
1238loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1239{
1240 struct loop_info64 info64;
1241
1242 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1243 return -EFAULT;
1244 return loop_set_status(lo, &info64);
1245}
1246
1247static int
1248loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1249 struct loop_info info;
1250 struct loop_info64 info64;
1251 int err = 0;
1252
1253 if (!arg)
1254 err = -EINVAL;
1255 if (!err)
1256 err = loop_get_status(lo, &info64);
1257 if (!err)
1258 err = loop_info64_to_old(&info64, &info);
1259 if (!err && copy_to_user(arg, &info, sizeof(info)))
1260 err = -EFAULT;
1261
1262 return err;
1263}
1264
1265static int
1266loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1267 struct loop_info64 info64;
1268 int err = 0;
1269
1270 if (!arg)
1271 err = -EINVAL;
1272 if (!err)
1273 err = loop_get_status(lo, &info64);
1274 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1275 err = -EFAULT;
1276
1277 return err;
1278}
1279
1280static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
1281{
1282 if (unlikely(lo->lo_state != Lo_bound))
1283 return -ENXIO;
1284
1285 return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
1286}
1287
1288static int lo_ioctl(struct block_device *bdev, fmode_t mode,
1289 unsigned int cmd, unsigned long arg)
1290{
1291 struct loop_device *lo = bdev->bd_disk->private_data;
1292 int err;
1293
1294 mutex_lock_nested(&lo->lo_ctl_mutex, 1);
1295 switch (cmd) {
1296 case LOOP_SET_FD:
1297 err = loop_set_fd(lo, mode, bdev, arg);
1298 break;
1299 case LOOP_CHANGE_FD:
1300 err = loop_change_fd(lo, bdev, arg);
1301 break;
1302 case LOOP_CLR_FD:
1303 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1304 err = loop_clr_fd(lo);
1305 if (!err)
1306 goto out_unlocked;
1307 break;
1308 case LOOP_SET_STATUS:
1309 err = -EPERM;
1310 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1311 err = loop_set_status_old(lo,
1312 (struct loop_info __user *)arg);
1313 break;
1314 case LOOP_GET_STATUS:
1315 err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1316 break;
1317 case LOOP_SET_STATUS64:
1318 err = -EPERM;
1319 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1320 err = loop_set_status64(lo,
1321 (struct loop_info64 __user *) arg);
1322 break;
1323 case LOOP_GET_STATUS64:
1324 err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1325 break;
1326 case LOOP_SET_CAPACITY:
1327 err = -EPERM;
1328 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1329 err = loop_set_capacity(lo, bdev);
1330 break;
1331 default:
1332 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1333 }
1334 mutex_unlock(&lo->lo_ctl_mutex);
1335
1336out_unlocked:
1337 return err;
1338}
1339
1340#ifdef CONFIG_COMPAT
1341struct compat_loop_info {
1342 compat_int_t lo_number; /* ioctl r/o */
1343 compat_dev_t lo_device; /* ioctl r/o */
1344 compat_ulong_t lo_inode; /* ioctl r/o */
1345 compat_dev_t lo_rdevice; /* ioctl r/o */
1346 compat_int_t lo_offset;
1347 compat_int_t lo_encrypt_type;
1348 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1349 compat_int_t lo_flags; /* ioctl r/o */
1350 char lo_name[LO_NAME_SIZE];
1351 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1352 compat_ulong_t lo_init[2];
1353 char reserved[4];
1354};
1355
1356/*
1357 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1358 * - noinlined to reduce stack space usage in main part of driver
1359 */
1360static noinline int
1361loop_info64_from_compat(const struct compat_loop_info __user *arg,
1362 struct loop_info64 *info64)
1363{
1364 struct compat_loop_info info;
1365
1366 if (copy_from_user(&info, arg, sizeof(info)))
1367 return -EFAULT;
1368
1369 memset(info64, 0, sizeof(*info64));
1370 info64->lo_number = info.lo_number;
1371 info64->lo_device = info.lo_device;
1372 info64->lo_inode = info.lo_inode;
1373 info64->lo_rdevice = info.lo_rdevice;
1374 info64->lo_offset = info.lo_offset;
1375 info64->lo_sizelimit = 0;
1376 info64->lo_encrypt_type = info.lo_encrypt_type;
1377 info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1378 info64->lo_flags = info.lo_flags;
1379 info64->lo_init[0] = info.lo_init[0];
1380 info64->lo_init[1] = info.lo_init[1];
1381 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1382 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1383 else
1384 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1385 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1386 return 0;
1387}
1388
1389/*
1390 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1391 * - noinlined to reduce stack space usage in main part of driver
1392 */
1393static noinline int
1394loop_info64_to_compat(const struct loop_info64 *info64,
1395 struct compat_loop_info __user *arg)
1396{
1397 struct compat_loop_info info;
1398
1399 memset(&info, 0, sizeof(info));
1400 info.lo_number = info64->lo_number;
1401 info.lo_device = info64->lo_device;
1402 info.lo_inode = info64->lo_inode;
1403 info.lo_rdevice = info64->lo_rdevice;
1404 info.lo_offset = info64->lo_offset;
1405 info.lo_encrypt_type = info64->lo_encrypt_type;
1406 info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
1407 info.lo_flags = info64->lo_flags;
1408 info.lo_init[0] = info64->lo_init[0];
1409 info.lo_init[1] = info64->lo_init[1];
1410 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1411 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1412 else
1413 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1414 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1415
1416 /* error in case values were truncated */
1417 if (info.lo_device != info64->lo_device ||
1418 info.lo_rdevice != info64->lo_rdevice ||
1419 info.lo_inode != info64->lo_inode ||
1420 info.lo_offset != info64->lo_offset ||
1421 info.lo_init[0] != info64->lo_init[0] ||
1422 info.lo_init[1] != info64->lo_init[1])
1423 return -EOVERFLOW;
1424
1425 if (copy_to_user(arg, &info, sizeof(info)))
1426 return -EFAULT;
1427 return 0;
1428}
1429
1430static int
1431loop_set_status_compat(struct loop_device *lo,
1432 const struct compat_loop_info __user *arg)
1433{
1434 struct loop_info64 info64;
1435 int ret;
1436
1437 ret = loop_info64_from_compat(arg, &info64);
1438 if (ret < 0)
1439 return ret;
1440 return loop_set_status(lo, &info64);
1441}
1442
1443static int
1444loop_get_status_compat(struct loop_device *lo,
1445 struct compat_loop_info __user *arg)
1446{
1447 struct loop_info64 info64;
1448 int err = 0;
1449
1450 if (!arg)
1451 err = -EINVAL;
1452 if (!err)
1453 err = loop_get_status(lo, &info64);
1454 if (!err)
1455 err = loop_info64_to_compat(&info64, arg);
1456 return err;
1457}
1458
1459static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1460 unsigned int cmd, unsigned long arg)
1461{
1462 struct loop_device *lo = bdev->bd_disk->private_data;
1463 int err;
1464
1465 switch(cmd) {
1466 case LOOP_SET_STATUS:
1467 mutex_lock(&lo->lo_ctl_mutex);
1468 err = loop_set_status_compat(
1469 lo, (const struct compat_loop_info __user *) arg);
1470 mutex_unlock(&lo->lo_ctl_mutex);
1471 break;
1472 case LOOP_GET_STATUS:
1473 mutex_lock(&lo->lo_ctl_mutex);
1474 err = loop_get_status_compat(
1475 lo, (struct compat_loop_info __user *) arg);
1476 mutex_unlock(&lo->lo_ctl_mutex);
1477 break;
1478 case LOOP_SET_CAPACITY:
1479 case LOOP_CLR_FD:
1480 case LOOP_GET_STATUS64:
1481 case LOOP_SET_STATUS64:
1482 arg = (unsigned long) compat_ptr(arg);
1483 case LOOP_SET_FD:
1484 case LOOP_CHANGE_FD:
1485 err = lo_ioctl(bdev, mode, cmd, arg);
1486 break;
1487 default:
1488 err = -ENOIOCTLCMD;
1489 break;
1490 }
1491 return err;
1492}
1493#endif
1494
1495static int lo_open(struct block_device *bdev, fmode_t mode)
1496{
1497 struct loop_device *lo;
1498 int err = 0;
1499
1500 mutex_lock(&loop_index_mutex);
1501 lo = bdev->bd_disk->private_data;
1502 if (!lo) {
1503 err = -ENXIO;
1504 goto out;
1505 }
1506
1507 mutex_lock(&lo->lo_ctl_mutex);
1508 lo->lo_refcnt++;
1509 mutex_unlock(&lo->lo_ctl_mutex);
1510out:
1511 mutex_unlock(&loop_index_mutex);
1512 return err;
1513}
1514
1515static void lo_release(struct gendisk *disk, fmode_t mode)
1516{
1517 struct loop_device *lo = disk->private_data;
1518 int err;
1519
1520 mutex_lock(&lo->lo_ctl_mutex);
1521
1522 if (--lo->lo_refcnt)
1523 goto out;
1524
1525 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
1526 /*
1527 * In autoclear mode, stop the loop thread
1528 * and remove configuration after last close.
1529 */
1530 err = loop_clr_fd(lo);
1531 if (!err)
1532 return;
1533 } else {
1534 /*
1535 * Otherwise keep thread (if running) and config,
1536 * but flush possible ongoing bios in thread.
1537 */
1538 loop_flush(lo);
1539 }
1540
1541out:
1542 mutex_unlock(&lo->lo_ctl_mutex);
1543}
1544
1545static const struct block_device_operations lo_fops = {
1546 .owner = THIS_MODULE,
1547 .open = lo_open,
1548 .release = lo_release,
1549 .ioctl = lo_ioctl,
1550#ifdef CONFIG_COMPAT
1551 .compat_ioctl = lo_compat_ioctl,
1552#endif
1553};
1554
1555/*
1556 * And now the modules code and kernel interface.
1557 */
1558static int max_loop;
1559module_param(max_loop, int, S_IRUGO);
1560MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1561module_param(max_part, int, S_IRUGO);
1562MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1563MODULE_LICENSE("GPL");
1564MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1565
1566int loop_register_transfer(struct loop_func_table *funcs)
1567{
1568 unsigned int n = funcs->number;
1569
1570 if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1571 return -EINVAL;
1572 xfer_funcs[n] = funcs;
1573 return 0;
1574}
1575
1576static int unregister_transfer_cb(int id, void *ptr, void *data)
1577{
1578 struct loop_device *lo = ptr;
1579 struct loop_func_table *xfer = data;
1580
1581 mutex_lock(&lo->lo_ctl_mutex);
1582 if (lo->lo_encryption == xfer)
1583 loop_release_xfer(lo);
1584 mutex_unlock(&lo->lo_ctl_mutex);
1585 return 0;
1586}
1587
1588int loop_unregister_transfer(int number)
1589{
1590 unsigned int n = number;
1591 struct loop_func_table *xfer;
1592
1593 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1594 return -EINVAL;
1595
1596 xfer_funcs[n] = NULL;
1597 idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
1598 return 0;
1599}
1600
1601EXPORT_SYMBOL(loop_register_transfer);
1602EXPORT_SYMBOL(loop_unregister_transfer);
1603
1604static int loop_add(struct loop_device **l, int i)
1605{
1606 struct loop_device *lo;
1607 struct gendisk *disk;
1608 int err;
1609
1610 err = -ENOMEM;
1611 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1612 if (!lo)
1613 goto out;
1614
1615 lo->lo_state = Lo_unbound;
1616
1617 /* allocate id, if @id >= 0, we're requesting that specific id */
1618 if (i >= 0) {
1619 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
1620 if (err == -ENOSPC)
1621 err = -EEXIST;
1622 } else {
1623 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
1624 }
1625 if (err < 0)
1626 goto out_free_dev;
1627 i = err;
1628
1629 err = -ENOMEM;
1630 lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
1631 if (!lo->lo_queue)
1632 goto out_free_idr;
1633
1634 /*
1635 * set queue make_request_fn
1636 */
1637 blk_queue_make_request(lo->lo_queue, loop_make_request);
1638 lo->lo_queue->queuedata = lo;
1639
1640 disk = lo->lo_disk = alloc_disk(1 << part_shift);
1641 if (!disk)
1642 goto out_free_queue;
1643
1644 /*
1645 * Disable partition scanning by default. The in-kernel partition
1646 * scanning can be requested individually per-device during its
1647 * setup. Userspace can always add and remove partitions from all
1648 * devices. The needed partition minors are allocated from the
1649 * extended minor space, the main loop device numbers will continue
1650 * to match the loop minors, regardless of the number of partitions
1651 * used.
1652 *
1653 * If max_part is given, partition scanning is globally enabled for
1654 * all loop devices. The minors for the main loop devices will be
1655 * multiples of max_part.
1656 *
1657 * Note: Global-for-all-devices, set-only-at-init, read-only module
1658 * parameteters like 'max_loop' and 'max_part' make things needlessly
1659 * complicated, are too static, inflexible and may surprise
1660 * userspace tools. Parameters like this in general should be avoided.
1661 */
1662 if (!part_shift)
1663 disk->flags |= GENHD_FL_NO_PART_SCAN;
1664 disk->flags |= GENHD_FL_EXT_DEVT;
1665 mutex_init(&lo->lo_ctl_mutex);
1666 lo->lo_number = i;
1667 lo->lo_thread = NULL;
1668 init_waitqueue_head(&lo->lo_event);
1669 init_waitqueue_head(&lo->lo_req_wait);
1670 spin_lock_init(&lo->lo_lock);
1671 disk->major = LOOP_MAJOR;
1672 disk->first_minor = i << part_shift;
1673 disk->fops = &lo_fops;
1674 disk->private_data = lo;
1675 disk->queue = lo->lo_queue;
1676 sprintf(disk->disk_name, "loop%d", i);
1677 add_disk(disk);
1678 *l = lo;
1679 return lo->lo_number;
1680
1681out_free_queue:
1682 blk_cleanup_queue(lo->lo_queue);
1683out_free_idr:
1684 idr_remove(&loop_index_idr, i);
1685out_free_dev:
1686 kfree(lo);
1687out:
1688 return err;
1689}
1690
1691static void loop_remove(struct loop_device *lo)
1692{
1693 del_gendisk(lo->lo_disk);
1694 blk_cleanup_queue(lo->lo_queue);
1695 put_disk(lo->lo_disk);
1696 kfree(lo);
1697}
1698
1699static int find_free_cb(int id, void *ptr, void *data)
1700{
1701 struct loop_device *lo = ptr;
1702 struct loop_device **l = data;
1703
1704 if (lo->lo_state == Lo_unbound) {
1705 *l = lo;
1706 return 1;
1707 }
1708 return 0;
1709}
1710
1711static int loop_lookup(struct loop_device **l, int i)
1712{
1713 struct loop_device *lo;
1714 int ret = -ENODEV;
1715
1716 if (i < 0) {
1717 int err;
1718
1719 err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
1720 if (err == 1) {
1721 *l = lo;
1722 ret = lo->lo_number;
1723 }
1724 goto out;
1725 }
1726
1727 /* lookup and return a specific i */
1728 lo = idr_find(&loop_index_idr, i);
1729 if (lo) {
1730 *l = lo;
1731 ret = lo->lo_number;
1732 }
1733out:
1734 return ret;
1735}
1736
1737static struct kobject *loop_probe(dev_t dev, int *part, void *data)
1738{
1739 struct loop_device *lo;
1740 struct kobject *kobj;
1741 int err;
1742
1743 mutex_lock(&loop_index_mutex);
1744 err = loop_lookup(&lo, MINOR(dev) >> part_shift);
1745 if (err < 0)
1746 err = loop_add(&lo, MINOR(dev) >> part_shift);
1747 if (err < 0)
1748 kobj = NULL;
1749 else
1750 kobj = get_disk(lo->lo_disk);
1751 mutex_unlock(&loop_index_mutex);
1752
1753 *part = 0;
1754 return kobj;
1755}
1756
1757static long loop_control_ioctl(struct file *file, unsigned int cmd,
1758 unsigned long parm)
1759{
1760 struct loop_device *lo;
1761 int ret = -ENOSYS;
1762
1763 mutex_lock(&loop_index_mutex);
1764 switch (cmd) {
1765 case LOOP_CTL_ADD:
1766 ret = loop_lookup(&lo, parm);
1767 if (ret >= 0) {
1768 ret = -EEXIST;
1769 break;
1770 }
1771 ret = loop_add(&lo, parm);
1772 break;
1773 case LOOP_CTL_REMOVE:
1774 ret = loop_lookup(&lo, parm);
1775 if (ret < 0)
1776 break;
1777 mutex_lock(&lo->lo_ctl_mutex);
1778 if (lo->lo_state != Lo_unbound) {
1779 ret = -EBUSY;
1780 mutex_unlock(&lo->lo_ctl_mutex);
1781 break;
1782 }
1783 if (lo->lo_refcnt > 0) {
1784 ret = -EBUSY;
1785 mutex_unlock(&lo->lo_ctl_mutex);
1786 break;
1787 }
1788 lo->lo_disk->private_data = NULL;
1789 mutex_unlock(&lo->lo_ctl_mutex);
1790 idr_remove(&loop_index_idr, lo->lo_number);
1791 loop_remove(lo);
1792 break;
1793 case LOOP_CTL_GET_FREE:
1794 ret = loop_lookup(&lo, -1);
1795 if (ret >= 0)
1796 break;
1797 ret = loop_add(&lo, -1);
1798 }
1799 mutex_unlock(&loop_index_mutex);
1800
1801 return ret;
1802}
1803
1804static const struct file_operations loop_ctl_fops = {
1805 .open = nonseekable_open,
1806 .unlocked_ioctl = loop_control_ioctl,
1807 .compat_ioctl = loop_control_ioctl,
1808 .owner = THIS_MODULE,
1809 .llseek = noop_llseek,
1810};
1811
1812static struct miscdevice loop_misc = {
1813 .minor = LOOP_CTRL_MINOR,
1814 .name = "loop-control",
1815 .fops = &loop_ctl_fops,
1816};
1817
1818MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
1819MODULE_ALIAS("devname:loop-control");
1820
1821static int __init loop_init(void)
1822{
1823 int i, nr;
1824 unsigned long range;
1825 struct loop_device *lo;
1826 int err;
1827
1828 err = misc_register(&loop_misc);
1829 if (err < 0)
1830 return err;
1831
1832 part_shift = 0;
1833 if (max_part > 0) {
1834 part_shift = fls(max_part);
1835
1836 /*
1837 * Adjust max_part according to part_shift as it is exported
1838 * to user space so that user can decide correct minor number
1839 * if [s]he want to create more devices.
1840 *
1841 * Note that -1 is required because partition 0 is reserved
1842 * for the whole disk.
1843 */
1844 max_part = (1UL << part_shift) - 1;
1845 }
1846
1847 if ((1UL << part_shift) > DISK_MAX_PARTS) {
1848 err = -EINVAL;
1849 goto misc_out;
1850 }
1851
1852 if (max_loop > 1UL << (MINORBITS - part_shift)) {
1853 err = -EINVAL;
1854 goto misc_out;
1855 }
1856
1857 /*
1858 * If max_loop is specified, create that many devices upfront.
1859 * This also becomes a hard limit. If max_loop is not specified,
1860 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1861 * init time. Loop devices can be requested on-demand with the
1862 * /dev/loop-control interface, or be instantiated by accessing
1863 * a 'dead' device node.
1864 */
1865 if (max_loop) {
1866 nr = max_loop;
1867 range = max_loop << part_shift;
1868 } else {
1869 nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1870 range = 1UL << MINORBITS;
1871 }
1872
1873 if (register_blkdev(LOOP_MAJOR, "loop")) {
1874 err = -EIO;
1875 goto misc_out;
1876 }
1877
1878 blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
1879 THIS_MODULE, loop_probe, NULL, NULL);
1880
1881 /* pre-create number of devices given by config or max_loop */
1882 mutex_lock(&loop_index_mutex);
1883 for (i = 0; i < nr; i++)
1884 loop_add(&lo, i);
1885 mutex_unlock(&loop_index_mutex);
1886
1887 printk(KERN_INFO "loop: module loaded\n");
1888 return 0;
1889
1890misc_out:
1891 misc_deregister(&loop_misc);
1892 return err;
1893}
1894
1895static int loop_exit_cb(int id, void *ptr, void *data)
1896{
1897 struct loop_device *lo = ptr;
1898
1899 loop_remove(lo);
1900 return 0;
1901}
1902
1903static void __exit loop_exit(void)
1904{
1905 unsigned long range;
1906
1907 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
1908
1909 idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
1910 idr_destroy(&loop_index_idr);
1911
1912 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
1913 unregister_blkdev(LOOP_MAJOR, "loop");
1914
1915 misc_deregister(&loop_misc);
1916}
1917
1918module_init(loop_init);
1919module_exit(loop_exit);
1920
1921#ifndef MODULE
1922static int __init max_loop_setup(char *str)
1923{
1924 max_loop = simple_strtol(str, NULL, 0);
1925 return 1;
1926}
1927
1928__setup("max_loop=", max_loop_setup);
1929#endif
1// 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
168/*
169 * We support direct I/O only if lo_offset is aligned with the logical I/O size
170 * of backing device, and the logical block size of loop is bigger than that of
171 * the backing device.
172 */
173static bool lo_bdev_can_use_dio(struct loop_device *lo,
174 struct block_device *backing_bdev)
175{
176 unsigned int sb_bsize = bdev_logical_block_size(backing_bdev);
177
178 if (queue_logical_block_size(lo->lo_queue) < sb_bsize)
179 return false;
180 if (lo->lo_offset & (sb_bsize - 1))
181 return false;
182 return true;
183}
184
185static void __loop_update_dio(struct loop_device *lo, bool dio)
186{
187 struct file *file = lo->lo_backing_file;
188 struct inode *inode = file->f_mapping->host;
189 struct block_device *backing_bdev = NULL;
190 bool use_dio;
191
192 if (S_ISBLK(inode->i_mode))
193 backing_bdev = I_BDEV(inode);
194 else if (inode->i_sb->s_bdev)
195 backing_bdev = inode->i_sb->s_bdev;
196
197 use_dio = dio && (file->f_mode & FMODE_CAN_ODIRECT) &&
198 (!backing_bdev || lo_bdev_can_use_dio(lo, backing_bdev));
199
200 if (lo->use_dio == use_dio)
201 return;
202
203 /* flush dirty pages before changing direct IO */
204 vfs_fsync(file, 0);
205
206 /*
207 * The flag of LO_FLAGS_DIRECT_IO is handled similarly with
208 * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup
209 * will get updated by ioctl(LOOP_GET_STATUS)
210 */
211 if (lo->lo_state == Lo_bound)
212 blk_mq_freeze_queue(lo->lo_queue);
213 lo->use_dio = use_dio;
214 if (use_dio)
215 lo->lo_flags |= LO_FLAGS_DIRECT_IO;
216 else
217 lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
218 if (lo->lo_state == Lo_bound)
219 blk_mq_unfreeze_queue(lo->lo_queue);
220}
221
222/**
223 * loop_set_size() - sets device size and notifies userspace
224 * @lo: struct loop_device to set the size for
225 * @size: new size of the loop device
226 *
227 * Callers must validate that the size passed into this function fits into
228 * a sector_t, eg using loop_validate_size()
229 */
230static void loop_set_size(struct loop_device *lo, loff_t size)
231{
232 if (!set_capacity_and_notify(lo->lo_disk, size))
233 kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
234}
235
236static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)
237{
238 struct iov_iter i;
239 ssize_t bw;
240
241 iov_iter_bvec(&i, ITER_SOURCE, bvec, 1, bvec->bv_len);
242
243 bw = vfs_iter_write(file, &i, ppos, 0);
244
245 if (likely(bw == bvec->bv_len))
246 return 0;
247
248 printk_ratelimited(KERN_ERR
249 "loop: Write error at byte offset %llu, length %i.\n",
250 (unsigned long long)*ppos, bvec->bv_len);
251 if (bw >= 0)
252 bw = -EIO;
253 return bw;
254}
255
256static int lo_write_simple(struct loop_device *lo, struct request *rq,
257 loff_t pos)
258{
259 struct bio_vec bvec;
260 struct req_iterator iter;
261 int ret = 0;
262
263 rq_for_each_segment(bvec, rq, iter) {
264 ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
265 if (ret < 0)
266 break;
267 cond_resched();
268 }
269
270 return ret;
271}
272
273static int lo_read_simple(struct loop_device *lo, struct request *rq,
274 loff_t pos)
275{
276 struct bio_vec bvec;
277 struct req_iterator iter;
278 struct iov_iter i;
279 ssize_t len;
280
281 rq_for_each_segment(bvec, rq, iter) {
282 iov_iter_bvec(&i, ITER_DEST, &bvec, 1, bvec.bv_len);
283 len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);
284 if (len < 0)
285 return len;
286
287 flush_dcache_page(bvec.bv_page);
288
289 if (len != bvec.bv_len) {
290 struct bio *bio;
291
292 __rq_for_each_bio(bio, rq)
293 zero_fill_bio(bio);
294 break;
295 }
296 cond_resched();
297 }
298
299 return 0;
300}
301
302static void loop_clear_limits(struct loop_device *lo, int mode)
303{
304 struct queue_limits lim = queue_limits_start_update(lo->lo_queue);
305
306 if (mode & FALLOC_FL_ZERO_RANGE)
307 lim.max_write_zeroes_sectors = 0;
308
309 if (mode & FALLOC_FL_PUNCH_HOLE) {
310 lim.max_hw_discard_sectors = 0;
311 lim.discard_granularity = 0;
312 }
313
314 queue_limits_commit_update(lo->lo_queue, &lim);
315}
316
317static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos,
318 int mode)
319{
320 /*
321 * We use fallocate to manipulate the space mappings used by the image
322 * a.k.a. discard/zerorange.
323 */
324 struct file *file = lo->lo_backing_file;
325 int ret;
326
327 mode |= FALLOC_FL_KEEP_SIZE;
328
329 if (!bdev_max_discard_sectors(lo->lo_device))
330 return -EOPNOTSUPP;
331
332 ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
333 if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
334 return -EIO;
335
336 /*
337 * We initially configure the limits in a hope that fallocate is
338 * supported and clear them here if that turns out not to be true.
339 */
340 if (unlikely(ret == -EOPNOTSUPP))
341 loop_clear_limits(lo, mode);
342
343 return ret;
344}
345
346static int lo_req_flush(struct loop_device *lo, struct request *rq)
347{
348 int ret = vfs_fsync(lo->lo_backing_file, 0);
349 if (unlikely(ret && ret != -EINVAL))
350 ret = -EIO;
351
352 return ret;
353}
354
355static void lo_complete_rq(struct request *rq)
356{
357 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
358 blk_status_t ret = BLK_STS_OK;
359
360 if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) ||
361 req_op(rq) != REQ_OP_READ) {
362 if (cmd->ret < 0)
363 ret = errno_to_blk_status(cmd->ret);
364 goto end_io;
365 }
366
367 /*
368 * Short READ - if we got some data, advance our request and
369 * retry it. If we got no data, end the rest with EIO.
370 */
371 if (cmd->ret) {
372 blk_update_request(rq, BLK_STS_OK, cmd->ret);
373 cmd->ret = 0;
374 blk_mq_requeue_request(rq, true);
375 } else {
376 if (cmd->use_aio) {
377 struct bio *bio = rq->bio;
378
379 while (bio) {
380 zero_fill_bio(bio);
381 bio = bio->bi_next;
382 }
383 }
384 ret = BLK_STS_IOERR;
385end_io:
386 blk_mq_end_request(rq, ret);
387 }
388}
389
390static void lo_rw_aio_do_completion(struct loop_cmd *cmd)
391{
392 struct request *rq = blk_mq_rq_from_pdu(cmd);
393
394 if (!atomic_dec_and_test(&cmd->ref))
395 return;
396 kfree(cmd->bvec);
397 cmd->bvec = NULL;
398 if (likely(!blk_should_fake_timeout(rq->q)))
399 blk_mq_complete_request(rq);
400}
401
402static void lo_rw_aio_complete(struct kiocb *iocb, long ret)
403{
404 struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb);
405
406 cmd->ret = ret;
407 lo_rw_aio_do_completion(cmd);
408}
409
410static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
411 loff_t pos, int rw)
412{
413 struct iov_iter iter;
414 struct req_iterator rq_iter;
415 struct bio_vec *bvec;
416 struct request *rq = blk_mq_rq_from_pdu(cmd);
417 struct bio *bio = rq->bio;
418 struct file *file = lo->lo_backing_file;
419 struct bio_vec tmp;
420 unsigned int offset;
421 int nr_bvec = 0;
422 int ret;
423
424 rq_for_each_bvec(tmp, rq, rq_iter)
425 nr_bvec++;
426
427 if (rq->bio != rq->biotail) {
428
429 bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec),
430 GFP_NOIO);
431 if (!bvec)
432 return -EIO;
433 cmd->bvec = bvec;
434
435 /*
436 * The bios of the request may be started from the middle of
437 * the 'bvec' because of bio splitting, so we can't directly
438 * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec
439 * API will take care of all details for us.
440 */
441 rq_for_each_bvec(tmp, rq, rq_iter) {
442 *bvec = tmp;
443 bvec++;
444 }
445 bvec = cmd->bvec;
446 offset = 0;
447 } else {
448 /*
449 * Same here, this bio may be started from the middle of the
450 * 'bvec' because of bio splitting, so offset from the bvec
451 * must be passed to iov iterator
452 */
453 offset = bio->bi_iter.bi_bvec_done;
454 bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
455 }
456 atomic_set(&cmd->ref, 2);
457
458 iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq));
459 iter.iov_offset = offset;
460
461 cmd->iocb.ki_pos = pos;
462 cmd->iocb.ki_filp = file;
463 cmd->iocb.ki_complete = lo_rw_aio_complete;
464 cmd->iocb.ki_flags = IOCB_DIRECT;
465 cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
466
467 if (rw == ITER_SOURCE)
468 ret = file->f_op->write_iter(&cmd->iocb, &iter);
469 else
470 ret = file->f_op->read_iter(&cmd->iocb, &iter);
471
472 lo_rw_aio_do_completion(cmd);
473
474 if (ret != -EIOCBQUEUED)
475 lo_rw_aio_complete(&cmd->iocb, ret);
476 return 0;
477}
478
479static int do_req_filebacked(struct loop_device *lo, struct request *rq)
480{
481 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
482 loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
483
484 /*
485 * lo_write_simple and lo_read_simple should have been covered
486 * by io submit style function like lo_rw_aio(), one blocker
487 * is that lo_read_simple() need to call flush_dcache_page after
488 * the page is written from kernel, and it isn't easy to handle
489 * this in io submit style function which submits all segments
490 * of the req at one time. And direct read IO doesn't need to
491 * run flush_dcache_page().
492 */
493 switch (req_op(rq)) {
494 case REQ_OP_FLUSH:
495 return lo_req_flush(lo, rq);
496 case REQ_OP_WRITE_ZEROES:
497 /*
498 * If the caller doesn't want deallocation, call zeroout to
499 * write zeroes the range. Otherwise, punch them out.
500 */
501 return lo_fallocate(lo, rq, pos,
502 (rq->cmd_flags & REQ_NOUNMAP) ?
503 FALLOC_FL_ZERO_RANGE :
504 FALLOC_FL_PUNCH_HOLE);
505 case REQ_OP_DISCARD:
506 return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE);
507 case REQ_OP_WRITE:
508 if (cmd->use_aio)
509 return lo_rw_aio(lo, cmd, pos, ITER_SOURCE);
510 else
511 return lo_write_simple(lo, rq, pos);
512 case REQ_OP_READ:
513 if (cmd->use_aio)
514 return lo_rw_aio(lo, cmd, pos, ITER_DEST);
515 else
516 return lo_read_simple(lo, rq, pos);
517 default:
518 WARN_ON_ONCE(1);
519 return -EIO;
520 }
521}
522
523static inline void loop_update_dio(struct loop_device *lo)
524{
525 __loop_update_dio(lo, (lo->lo_backing_file->f_flags & O_DIRECT) |
526 lo->use_dio);
527}
528
529static void loop_reread_partitions(struct loop_device *lo)
530{
531 int rc;
532
533 mutex_lock(&lo->lo_disk->open_mutex);
534 rc = bdev_disk_changed(lo->lo_disk, false);
535 mutex_unlock(&lo->lo_disk->open_mutex);
536 if (rc)
537 pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
538 __func__, lo->lo_number, lo->lo_file_name, rc);
539}
540
541static inline int is_loop_device(struct file *file)
542{
543 struct inode *i = file->f_mapping->host;
544
545 return i && S_ISBLK(i->i_mode) && imajor(i) == LOOP_MAJOR;
546}
547
548static int loop_validate_file(struct file *file, struct block_device *bdev)
549{
550 struct inode *inode = file->f_mapping->host;
551 struct file *f = file;
552
553 /* Avoid recursion */
554 while (is_loop_device(f)) {
555 struct loop_device *l;
556
557 lockdep_assert_held(&loop_validate_mutex);
558 if (f->f_mapping->host->i_rdev == bdev->bd_dev)
559 return -EBADF;
560
561 l = I_BDEV(f->f_mapping->host)->bd_disk->private_data;
562 if (l->lo_state != Lo_bound)
563 return -EINVAL;
564 /* Order wrt setting lo->lo_backing_file in loop_configure(). */
565 rmb();
566 f = l->lo_backing_file;
567 }
568 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
569 return -EINVAL;
570 return 0;
571}
572
573/*
574 * loop_change_fd switched the backing store of a loopback device to
575 * a new file. This is useful for operating system installers to free up
576 * the original file and in High Availability environments to switch to
577 * an alternative location for the content in case of server meltdown.
578 * This can only work if the loop device is used read-only, and if the
579 * new backing store is the same size and type as the old backing store.
580 */
581static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
582 unsigned int arg)
583{
584 struct file *file = fget(arg);
585 struct file *old_file;
586 int error;
587 bool partscan;
588 bool is_loop;
589
590 if (!file)
591 return -EBADF;
592
593 /* suppress uevents while reconfiguring the device */
594 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
595
596 is_loop = is_loop_device(file);
597 error = loop_global_lock_killable(lo, is_loop);
598 if (error)
599 goto out_putf;
600 error = -ENXIO;
601 if (lo->lo_state != Lo_bound)
602 goto out_err;
603
604 /* the loop device has to be read-only */
605 error = -EINVAL;
606 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
607 goto out_err;
608
609 error = loop_validate_file(file, bdev);
610 if (error)
611 goto out_err;
612
613 old_file = lo->lo_backing_file;
614
615 error = -EINVAL;
616
617 /* size of the new backing store needs to be the same */
618 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
619 goto out_err;
620
621 /* and ... switch */
622 disk_force_media_change(lo->lo_disk);
623 blk_mq_freeze_queue(lo->lo_queue);
624 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
625 lo->lo_backing_file = file;
626 lo->old_gfp_mask = mapping_gfp_mask(file->f_mapping);
627 mapping_set_gfp_mask(file->f_mapping,
628 lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
629 loop_update_dio(lo);
630 blk_mq_unfreeze_queue(lo->lo_queue);
631 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
632 loop_global_unlock(lo, is_loop);
633
634 /*
635 * Flush loop_validate_file() before fput(), for l->lo_backing_file
636 * might be pointing at old_file which might be the last reference.
637 */
638 if (!is_loop) {
639 mutex_lock(&loop_validate_mutex);
640 mutex_unlock(&loop_validate_mutex);
641 }
642 /*
643 * We must drop file reference outside of lo_mutex as dropping
644 * the file ref can take open_mutex which creates circular locking
645 * dependency.
646 */
647 fput(old_file);
648 if (partscan)
649 loop_reread_partitions(lo);
650
651 error = 0;
652done:
653 /* enable and uncork uevent now that we are done */
654 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
655 return error;
656
657out_err:
658 loop_global_unlock(lo, is_loop);
659out_putf:
660 fput(file);
661 goto done;
662}
663
664/* loop sysfs attributes */
665
666static ssize_t loop_attr_show(struct device *dev, char *page,
667 ssize_t (*callback)(struct loop_device *, char *))
668{
669 struct gendisk *disk = dev_to_disk(dev);
670 struct loop_device *lo = disk->private_data;
671
672 return callback(lo, page);
673}
674
675#define LOOP_ATTR_RO(_name) \
676static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
677static ssize_t loop_attr_do_show_##_name(struct device *d, \
678 struct device_attribute *attr, char *b) \
679{ \
680 return loop_attr_show(d, b, loop_attr_##_name##_show); \
681} \
682static struct device_attribute loop_attr_##_name = \
683 __ATTR(_name, 0444, loop_attr_do_show_##_name, NULL);
684
685static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
686{
687 ssize_t ret;
688 char *p = NULL;
689
690 spin_lock_irq(&lo->lo_lock);
691 if (lo->lo_backing_file)
692 p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1);
693 spin_unlock_irq(&lo->lo_lock);
694
695 if (IS_ERR_OR_NULL(p))
696 ret = PTR_ERR(p);
697 else {
698 ret = strlen(p);
699 memmove(buf, p, ret);
700 buf[ret++] = '\n';
701 buf[ret] = 0;
702 }
703
704 return ret;
705}
706
707static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
708{
709 return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_offset);
710}
711
712static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
713{
714 return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
715}
716
717static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
718{
719 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
720
721 return sysfs_emit(buf, "%s\n", autoclear ? "1" : "0");
722}
723
724static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
725{
726 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
727
728 return sysfs_emit(buf, "%s\n", partscan ? "1" : "0");
729}
730
731static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf)
732{
733 int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO);
734
735 return sysfs_emit(buf, "%s\n", dio ? "1" : "0");
736}
737
738LOOP_ATTR_RO(backing_file);
739LOOP_ATTR_RO(offset);
740LOOP_ATTR_RO(sizelimit);
741LOOP_ATTR_RO(autoclear);
742LOOP_ATTR_RO(partscan);
743LOOP_ATTR_RO(dio);
744
745static struct attribute *loop_attrs[] = {
746 &loop_attr_backing_file.attr,
747 &loop_attr_offset.attr,
748 &loop_attr_sizelimit.attr,
749 &loop_attr_autoclear.attr,
750 &loop_attr_partscan.attr,
751 &loop_attr_dio.attr,
752 NULL,
753};
754
755static struct attribute_group loop_attribute_group = {
756 .name = "loop",
757 .attrs= loop_attrs,
758};
759
760static void loop_sysfs_init(struct loop_device *lo)
761{
762 lo->sysfs_inited = !sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
763 &loop_attribute_group);
764}
765
766static void loop_sysfs_exit(struct loop_device *lo)
767{
768 if (lo->sysfs_inited)
769 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
770 &loop_attribute_group);
771}
772
773static void loop_get_discard_config(struct loop_device *lo,
774 u32 *granularity, u32 *max_discard_sectors)
775{
776 struct file *file = lo->lo_backing_file;
777 struct inode *inode = file->f_mapping->host;
778 struct kstatfs sbuf;
779
780 /*
781 * If the backing device is a block device, mirror its zeroing
782 * capability. Set the discard sectors to the block device's zeroing
783 * capabilities because loop discards result in blkdev_issue_zeroout(),
784 * not blkdev_issue_discard(). This maintains consistent behavior with
785 * file-backed loop devices: discarded regions read back as zero.
786 */
787 if (S_ISBLK(inode->i_mode)) {
788 struct block_device *bdev = I_BDEV(inode);
789
790 *max_discard_sectors = bdev_write_zeroes_sectors(bdev);
791 *granularity = bdev_discard_granularity(bdev);
792
793 /*
794 * We use punch hole to reclaim the free space used by the
795 * image a.k.a. discard.
796 */
797 } else if (file->f_op->fallocate && !vfs_statfs(&file->f_path, &sbuf)) {
798 *max_discard_sectors = UINT_MAX >> 9;
799 *granularity = sbuf.f_bsize;
800 }
801}
802
803struct loop_worker {
804 struct rb_node rb_node;
805 struct work_struct work;
806 struct list_head cmd_list;
807 struct list_head idle_list;
808 struct loop_device *lo;
809 struct cgroup_subsys_state *blkcg_css;
810 unsigned long last_ran_at;
811};
812
813static void loop_workfn(struct work_struct *work);
814
815#ifdef CONFIG_BLK_CGROUP
816static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
817{
818 return !css || css == blkcg_root_css;
819}
820#else
821static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
822{
823 return !css;
824}
825#endif
826
827static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd)
828{
829 struct rb_node **node, *parent = NULL;
830 struct loop_worker *cur_worker, *worker = NULL;
831 struct work_struct *work;
832 struct list_head *cmd_list;
833
834 spin_lock_irq(&lo->lo_work_lock);
835
836 if (queue_on_root_worker(cmd->blkcg_css))
837 goto queue_work;
838
839 node = &lo->worker_tree.rb_node;
840
841 while (*node) {
842 parent = *node;
843 cur_worker = container_of(*node, struct loop_worker, rb_node);
844 if (cur_worker->blkcg_css == cmd->blkcg_css) {
845 worker = cur_worker;
846 break;
847 } else if ((long)cur_worker->blkcg_css < (long)cmd->blkcg_css) {
848 node = &(*node)->rb_left;
849 } else {
850 node = &(*node)->rb_right;
851 }
852 }
853 if (worker)
854 goto queue_work;
855
856 worker = kzalloc(sizeof(struct loop_worker), GFP_NOWAIT | __GFP_NOWARN);
857 /*
858 * In the event we cannot allocate a worker, just queue on the
859 * rootcg worker and issue the I/O as the rootcg
860 */
861 if (!worker) {
862 cmd->blkcg_css = NULL;
863 if (cmd->memcg_css)
864 css_put(cmd->memcg_css);
865 cmd->memcg_css = NULL;
866 goto queue_work;
867 }
868
869 worker->blkcg_css = cmd->blkcg_css;
870 css_get(worker->blkcg_css);
871 INIT_WORK(&worker->work, loop_workfn);
872 INIT_LIST_HEAD(&worker->cmd_list);
873 INIT_LIST_HEAD(&worker->idle_list);
874 worker->lo = lo;
875 rb_link_node(&worker->rb_node, parent, node);
876 rb_insert_color(&worker->rb_node, &lo->worker_tree);
877queue_work:
878 if (worker) {
879 /*
880 * We need to remove from the idle list here while
881 * holding the lock so that the idle timer doesn't
882 * free the worker
883 */
884 if (!list_empty(&worker->idle_list))
885 list_del_init(&worker->idle_list);
886 work = &worker->work;
887 cmd_list = &worker->cmd_list;
888 } else {
889 work = &lo->rootcg_work;
890 cmd_list = &lo->rootcg_cmd_list;
891 }
892 list_add_tail(&cmd->list_entry, cmd_list);
893 queue_work(lo->workqueue, work);
894 spin_unlock_irq(&lo->lo_work_lock);
895}
896
897static void loop_set_timer(struct loop_device *lo)
898{
899 timer_reduce(&lo->timer, jiffies + LOOP_IDLE_WORKER_TIMEOUT);
900}
901
902static void loop_free_idle_workers(struct loop_device *lo, bool delete_all)
903{
904 struct loop_worker *pos, *worker;
905
906 spin_lock_irq(&lo->lo_work_lock);
907 list_for_each_entry_safe(worker, pos, &lo->idle_worker_list,
908 idle_list) {
909 if (!delete_all &&
910 time_is_after_jiffies(worker->last_ran_at +
911 LOOP_IDLE_WORKER_TIMEOUT))
912 break;
913 list_del(&worker->idle_list);
914 rb_erase(&worker->rb_node, &lo->worker_tree);
915 css_put(worker->blkcg_css);
916 kfree(worker);
917 }
918 if (!list_empty(&lo->idle_worker_list))
919 loop_set_timer(lo);
920 spin_unlock_irq(&lo->lo_work_lock);
921}
922
923static void loop_free_idle_workers_timer(struct timer_list *timer)
924{
925 struct loop_device *lo = container_of(timer, struct loop_device, timer);
926
927 return loop_free_idle_workers(lo, false);
928}
929
930/**
931 * loop_set_status_from_info - configure device from loop_info
932 * @lo: struct loop_device to configure
933 * @info: struct loop_info64 to configure the device with
934 *
935 * Configures the loop device parameters according to the passed
936 * in loop_info64 configuration.
937 */
938static int
939loop_set_status_from_info(struct loop_device *lo,
940 const struct loop_info64 *info)
941{
942 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
943 return -EINVAL;
944
945 switch (info->lo_encrypt_type) {
946 case LO_CRYPT_NONE:
947 break;
948 case LO_CRYPT_XOR:
949 pr_warn("support for the xor transformation has been removed.\n");
950 return -EINVAL;
951 case LO_CRYPT_CRYPTOAPI:
952 pr_warn("support for cryptoloop has been removed. Use dm-crypt instead.\n");
953 return -EINVAL;
954 default:
955 return -EINVAL;
956 }
957
958 /* Avoid assigning overflow values */
959 if (info->lo_offset > LLONG_MAX || info->lo_sizelimit > LLONG_MAX)
960 return -EOVERFLOW;
961
962 lo->lo_offset = info->lo_offset;
963 lo->lo_sizelimit = info->lo_sizelimit;
964
965 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
966 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
967 lo->lo_flags = info->lo_flags;
968 return 0;
969}
970
971static unsigned int loop_default_blocksize(struct loop_device *lo,
972 struct block_device *backing_bdev)
973{
974 /* In case of direct I/O, match underlying block size */
975 if ((lo->lo_backing_file->f_flags & O_DIRECT) && backing_bdev)
976 return bdev_logical_block_size(backing_bdev);
977 return SECTOR_SIZE;
978}
979
980static int loop_reconfigure_limits(struct loop_device *lo, unsigned int bsize)
981{
982 struct file *file = lo->lo_backing_file;
983 struct inode *inode = file->f_mapping->host;
984 struct block_device *backing_bdev = NULL;
985 struct queue_limits lim;
986 u32 granularity = 0, max_discard_sectors = 0;
987
988 if (S_ISBLK(inode->i_mode))
989 backing_bdev = I_BDEV(inode);
990 else if (inode->i_sb->s_bdev)
991 backing_bdev = inode->i_sb->s_bdev;
992
993 if (!bsize)
994 bsize = loop_default_blocksize(lo, backing_bdev);
995
996 loop_get_discard_config(lo, &granularity, &max_discard_sectors);
997
998 lim = queue_limits_start_update(lo->lo_queue);
999 lim.logical_block_size = bsize;
1000 lim.physical_block_size = bsize;
1001 lim.io_min = bsize;
1002 lim.features &= ~(BLK_FEAT_WRITE_CACHE | BLK_FEAT_ROTATIONAL);
1003 if (file->f_op->fsync && !(lo->lo_flags & LO_FLAGS_READ_ONLY))
1004 lim.features |= BLK_FEAT_WRITE_CACHE;
1005 if (backing_bdev && !bdev_nonrot(backing_bdev))
1006 lim.features |= BLK_FEAT_ROTATIONAL;
1007 lim.max_hw_discard_sectors = max_discard_sectors;
1008 lim.max_write_zeroes_sectors = max_discard_sectors;
1009 if (max_discard_sectors)
1010 lim.discard_granularity = granularity;
1011 else
1012 lim.discard_granularity = 0;
1013 return queue_limits_commit_update(lo->lo_queue, &lim);
1014}
1015
1016static int loop_configure(struct loop_device *lo, blk_mode_t mode,
1017 struct block_device *bdev,
1018 const struct loop_config *config)
1019{
1020 struct file *file = fget(config->fd);
1021 struct address_space *mapping;
1022 int error;
1023 loff_t size;
1024 bool partscan;
1025 bool is_loop;
1026
1027 if (!file)
1028 return -EBADF;
1029 is_loop = is_loop_device(file);
1030
1031 /* This is safe, since we have a reference from open(). */
1032 __module_get(THIS_MODULE);
1033
1034 /*
1035 * If we don't hold exclusive handle for the device, upgrade to it
1036 * here to avoid changing device under exclusive owner.
1037 */
1038 if (!(mode & BLK_OPEN_EXCL)) {
1039 error = bd_prepare_to_claim(bdev, loop_configure, NULL);
1040 if (error)
1041 goto out_putf;
1042 }
1043
1044 error = loop_global_lock_killable(lo, is_loop);
1045 if (error)
1046 goto out_bdev;
1047
1048 error = -EBUSY;
1049 if (lo->lo_state != Lo_unbound)
1050 goto out_unlock;
1051
1052 error = loop_validate_file(file, bdev);
1053 if (error)
1054 goto out_unlock;
1055
1056 mapping = file->f_mapping;
1057
1058 if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) {
1059 error = -EINVAL;
1060 goto out_unlock;
1061 }
1062
1063 error = loop_set_status_from_info(lo, &config->info);
1064 if (error)
1065 goto out_unlock;
1066
1067 if (!(file->f_mode & FMODE_WRITE) || !(mode & BLK_OPEN_WRITE) ||
1068 !file->f_op->write_iter)
1069 lo->lo_flags |= LO_FLAGS_READ_ONLY;
1070
1071 if (!lo->workqueue) {
1072 lo->workqueue = alloc_workqueue("loop%d",
1073 WQ_UNBOUND | WQ_FREEZABLE,
1074 0, lo->lo_number);
1075 if (!lo->workqueue) {
1076 error = -ENOMEM;
1077 goto out_unlock;
1078 }
1079 }
1080
1081 /* suppress uevents while reconfiguring the device */
1082 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
1083
1084 disk_force_media_change(lo->lo_disk);
1085 set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0);
1086
1087 lo->use_dio = lo->lo_flags & LO_FLAGS_DIRECT_IO;
1088 lo->lo_device = bdev;
1089 lo->lo_backing_file = file;
1090 lo->old_gfp_mask = mapping_gfp_mask(mapping);
1091 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
1092
1093 error = loop_reconfigure_limits(lo, config->block_size);
1094 if (error)
1095 goto out_unlock;
1096
1097 loop_update_dio(lo);
1098 loop_sysfs_init(lo);
1099
1100 size = get_loop_size(lo, file);
1101 loop_set_size(lo, size);
1102
1103 /* Order wrt reading lo_state in loop_validate_file(). */
1104 wmb();
1105
1106 lo->lo_state = Lo_bound;
1107 if (part_shift)
1108 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1109 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
1110 if (partscan)
1111 clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1112
1113 /* enable and uncork uevent now that we are done */
1114 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
1115
1116 loop_global_unlock(lo, is_loop);
1117 if (partscan)
1118 loop_reread_partitions(lo);
1119
1120 if (!(mode & BLK_OPEN_EXCL))
1121 bd_abort_claiming(bdev, loop_configure);
1122
1123 return 0;
1124
1125out_unlock:
1126 loop_global_unlock(lo, is_loop);
1127out_bdev:
1128 if (!(mode & BLK_OPEN_EXCL))
1129 bd_abort_claiming(bdev, loop_configure);
1130out_putf:
1131 fput(file);
1132 /* This is safe: open() is still holding a reference. */
1133 module_put(THIS_MODULE);
1134 return error;
1135}
1136
1137static void __loop_clr_fd(struct loop_device *lo)
1138{
1139 struct queue_limits lim;
1140 struct file *filp;
1141 gfp_t gfp = lo->old_gfp_mask;
1142
1143 spin_lock_irq(&lo->lo_lock);
1144 filp = lo->lo_backing_file;
1145 lo->lo_backing_file = NULL;
1146 spin_unlock_irq(&lo->lo_lock);
1147
1148 lo->lo_device = NULL;
1149 lo->lo_offset = 0;
1150 lo->lo_sizelimit = 0;
1151 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1152
1153 /* reset the block size to the default */
1154 lim = queue_limits_start_update(lo->lo_queue);
1155 lim.logical_block_size = SECTOR_SIZE;
1156 lim.physical_block_size = SECTOR_SIZE;
1157 lim.io_min = SECTOR_SIZE;
1158 queue_limits_commit_update(lo->lo_queue, &lim);
1159
1160 invalidate_disk(lo->lo_disk);
1161 loop_sysfs_exit(lo);
1162 /* let user-space know about this change */
1163 kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
1164 mapping_set_gfp_mask(filp->f_mapping, gfp);
1165 /* This is safe: open() is still holding a reference. */
1166 module_put(THIS_MODULE);
1167
1168 disk_force_media_change(lo->lo_disk);
1169
1170 if (lo->lo_flags & LO_FLAGS_PARTSCAN) {
1171 int err;
1172
1173 /*
1174 * open_mutex has been held already in release path, so don't
1175 * acquire it if this function is called in such case.
1176 *
1177 * If the reread partition isn't from release path, lo_refcnt
1178 * must be at least one and it can only become zero when the
1179 * current holder is released.
1180 */
1181 err = bdev_disk_changed(lo->lo_disk, false);
1182 if (err)
1183 pr_warn("%s: partition scan of loop%d failed (rc=%d)\n",
1184 __func__, lo->lo_number, err);
1185 /* Device is gone, no point in returning error */
1186 }
1187
1188 /*
1189 * lo->lo_state is set to Lo_unbound here after above partscan has
1190 * finished. There cannot be anybody else entering __loop_clr_fd() as
1191 * Lo_rundown state protects us from all the other places trying to
1192 * change the 'lo' device.
1193 */
1194 lo->lo_flags = 0;
1195 if (!part_shift)
1196 set_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1197 mutex_lock(&lo->lo_mutex);
1198 lo->lo_state = Lo_unbound;
1199 mutex_unlock(&lo->lo_mutex);
1200
1201 /*
1202 * Need not hold lo_mutex to fput backing file. Calling fput holding
1203 * lo_mutex triggers a circular lock dependency possibility warning as
1204 * fput can take open_mutex which is usually taken before lo_mutex.
1205 */
1206 fput(filp);
1207}
1208
1209static int loop_clr_fd(struct loop_device *lo)
1210{
1211 int err;
1212
1213 /*
1214 * Since lo_ioctl() is called without locks held, it is possible that
1215 * loop_configure()/loop_change_fd() and loop_clr_fd() run in parallel.
1216 *
1217 * Therefore, use global lock when setting Lo_rundown state in order to
1218 * make sure that loop_validate_file() will fail if the "struct file"
1219 * which loop_configure()/loop_change_fd() found via fget() was this
1220 * loop device.
1221 */
1222 err = loop_global_lock_killable(lo, true);
1223 if (err)
1224 return err;
1225 if (lo->lo_state != Lo_bound) {
1226 loop_global_unlock(lo, true);
1227 return -ENXIO;
1228 }
1229 /*
1230 * Mark the device for removing the backing device on last close.
1231 * If we are the only opener, also switch the state to roundown here to
1232 * prevent new openers from coming in.
1233 */
1234
1235 lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
1236 if (disk_openers(lo->lo_disk) == 1)
1237 lo->lo_state = Lo_rundown;
1238 loop_global_unlock(lo, true);
1239
1240 return 0;
1241}
1242
1243static int
1244loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1245{
1246 int err;
1247 int prev_lo_flags;
1248 bool partscan = false;
1249 bool size_changed = false;
1250
1251 err = mutex_lock_killable(&lo->lo_mutex);
1252 if (err)
1253 return err;
1254 if (lo->lo_state != Lo_bound) {
1255 err = -ENXIO;
1256 goto out_unlock;
1257 }
1258
1259 if (lo->lo_offset != info->lo_offset ||
1260 lo->lo_sizelimit != info->lo_sizelimit) {
1261 size_changed = true;
1262 sync_blockdev(lo->lo_device);
1263 invalidate_bdev(lo->lo_device);
1264 }
1265
1266 /* I/O need to be drained during transfer transition */
1267 blk_mq_freeze_queue(lo->lo_queue);
1268
1269 prev_lo_flags = lo->lo_flags;
1270
1271 err = loop_set_status_from_info(lo, info);
1272 if (err)
1273 goto out_unfreeze;
1274
1275 /* Mask out flags that can't be set using LOOP_SET_STATUS. */
1276 lo->lo_flags &= LOOP_SET_STATUS_SETTABLE_FLAGS;
1277 /* For those flags, use the previous values instead */
1278 lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_SETTABLE_FLAGS;
1279 /* For flags that can't be cleared, use previous values too */
1280 lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_CLEARABLE_FLAGS;
1281
1282 if (size_changed) {
1283 loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit,
1284 lo->lo_backing_file);
1285 loop_set_size(lo, new_size);
1286 }
1287
1288 /* update dio if lo_offset or transfer is changed */
1289 __loop_update_dio(lo, lo->use_dio);
1290
1291out_unfreeze:
1292 blk_mq_unfreeze_queue(lo->lo_queue);
1293
1294 if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) &&
1295 !(prev_lo_flags & LO_FLAGS_PARTSCAN)) {
1296 clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1297 partscan = true;
1298 }
1299out_unlock:
1300 mutex_unlock(&lo->lo_mutex);
1301 if (partscan)
1302 loop_reread_partitions(lo);
1303
1304 return err;
1305}
1306
1307static int
1308loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1309{
1310 struct path path;
1311 struct kstat stat;
1312 int ret;
1313
1314 ret = mutex_lock_killable(&lo->lo_mutex);
1315 if (ret)
1316 return ret;
1317 if (lo->lo_state != Lo_bound) {
1318 mutex_unlock(&lo->lo_mutex);
1319 return -ENXIO;
1320 }
1321
1322 memset(info, 0, sizeof(*info));
1323 info->lo_number = lo->lo_number;
1324 info->lo_offset = lo->lo_offset;
1325 info->lo_sizelimit = lo->lo_sizelimit;
1326 info->lo_flags = lo->lo_flags;
1327 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1328
1329 /* Drop lo_mutex while we call into the filesystem. */
1330 path = lo->lo_backing_file->f_path;
1331 path_get(&path);
1332 mutex_unlock(&lo->lo_mutex);
1333 ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT);
1334 if (!ret) {
1335 info->lo_device = huge_encode_dev(stat.dev);
1336 info->lo_inode = stat.ino;
1337 info->lo_rdevice = huge_encode_dev(stat.rdev);
1338 }
1339 path_put(&path);
1340 return ret;
1341}
1342
1343static void
1344loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1345{
1346 memset(info64, 0, sizeof(*info64));
1347 info64->lo_number = info->lo_number;
1348 info64->lo_device = info->lo_device;
1349 info64->lo_inode = info->lo_inode;
1350 info64->lo_rdevice = info->lo_rdevice;
1351 info64->lo_offset = info->lo_offset;
1352 info64->lo_sizelimit = 0;
1353 info64->lo_flags = info->lo_flags;
1354 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1355}
1356
1357static int
1358loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1359{
1360 memset(info, 0, sizeof(*info));
1361 info->lo_number = info64->lo_number;
1362 info->lo_device = info64->lo_device;
1363 info->lo_inode = info64->lo_inode;
1364 info->lo_rdevice = info64->lo_rdevice;
1365 info->lo_offset = info64->lo_offset;
1366 info->lo_flags = info64->lo_flags;
1367 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1368
1369 /* error in case values were truncated */
1370 if (info->lo_device != info64->lo_device ||
1371 info->lo_rdevice != info64->lo_rdevice ||
1372 info->lo_inode != info64->lo_inode ||
1373 info->lo_offset != info64->lo_offset)
1374 return -EOVERFLOW;
1375
1376 return 0;
1377}
1378
1379static int
1380loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1381{
1382 struct loop_info info;
1383 struct loop_info64 info64;
1384
1385 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1386 return -EFAULT;
1387 loop_info64_from_old(&info, &info64);
1388 return loop_set_status(lo, &info64);
1389}
1390
1391static int
1392loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1393{
1394 struct loop_info64 info64;
1395
1396 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1397 return -EFAULT;
1398 return loop_set_status(lo, &info64);
1399}
1400
1401static int
1402loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1403 struct loop_info info;
1404 struct loop_info64 info64;
1405 int err;
1406
1407 if (!arg)
1408 return -EINVAL;
1409 err = loop_get_status(lo, &info64);
1410 if (!err)
1411 err = loop_info64_to_old(&info64, &info);
1412 if (!err && copy_to_user(arg, &info, sizeof(info)))
1413 err = -EFAULT;
1414
1415 return err;
1416}
1417
1418static int
1419loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1420 struct loop_info64 info64;
1421 int err;
1422
1423 if (!arg)
1424 return -EINVAL;
1425 err = loop_get_status(lo, &info64);
1426 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1427 err = -EFAULT;
1428
1429 return err;
1430}
1431
1432static int loop_set_capacity(struct loop_device *lo)
1433{
1434 loff_t size;
1435
1436 if (unlikely(lo->lo_state != Lo_bound))
1437 return -ENXIO;
1438
1439 size = get_loop_size(lo, lo->lo_backing_file);
1440 loop_set_size(lo, size);
1441
1442 return 0;
1443}
1444
1445static int loop_set_dio(struct loop_device *lo, unsigned long arg)
1446{
1447 int error = -ENXIO;
1448 if (lo->lo_state != Lo_bound)
1449 goto out;
1450
1451 __loop_update_dio(lo, !!arg);
1452 if (lo->use_dio == !!arg)
1453 return 0;
1454 error = -EINVAL;
1455 out:
1456 return error;
1457}
1458
1459static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
1460{
1461 int err = 0;
1462
1463 if (lo->lo_state != Lo_bound)
1464 return -ENXIO;
1465
1466 if (lo->lo_queue->limits.logical_block_size == arg)
1467 return 0;
1468
1469 sync_blockdev(lo->lo_device);
1470 invalidate_bdev(lo->lo_device);
1471
1472 blk_mq_freeze_queue(lo->lo_queue);
1473 err = loop_reconfigure_limits(lo, arg);
1474 loop_update_dio(lo);
1475 blk_mq_unfreeze_queue(lo->lo_queue);
1476
1477 return err;
1478}
1479
1480static int lo_simple_ioctl(struct loop_device *lo, unsigned int cmd,
1481 unsigned long arg)
1482{
1483 int err;
1484
1485 err = mutex_lock_killable(&lo->lo_mutex);
1486 if (err)
1487 return err;
1488 switch (cmd) {
1489 case LOOP_SET_CAPACITY:
1490 err = loop_set_capacity(lo);
1491 break;
1492 case LOOP_SET_DIRECT_IO:
1493 err = loop_set_dio(lo, arg);
1494 break;
1495 case LOOP_SET_BLOCK_SIZE:
1496 err = loop_set_block_size(lo, arg);
1497 break;
1498 default:
1499 err = -EINVAL;
1500 }
1501 mutex_unlock(&lo->lo_mutex);
1502 return err;
1503}
1504
1505static int lo_ioctl(struct block_device *bdev, blk_mode_t mode,
1506 unsigned int cmd, unsigned long arg)
1507{
1508 struct loop_device *lo = bdev->bd_disk->private_data;
1509 void __user *argp = (void __user *) arg;
1510 int err;
1511
1512 switch (cmd) {
1513 case LOOP_SET_FD: {
1514 /*
1515 * Legacy case - pass in a zeroed out struct loop_config with
1516 * only the file descriptor set , which corresponds with the
1517 * default parameters we'd have used otherwise.
1518 */
1519 struct loop_config config;
1520
1521 memset(&config, 0, sizeof(config));
1522 config.fd = arg;
1523
1524 return loop_configure(lo, mode, bdev, &config);
1525 }
1526 case LOOP_CONFIGURE: {
1527 struct loop_config config;
1528
1529 if (copy_from_user(&config, argp, sizeof(config)))
1530 return -EFAULT;
1531
1532 return loop_configure(lo, mode, bdev, &config);
1533 }
1534 case LOOP_CHANGE_FD:
1535 return loop_change_fd(lo, bdev, arg);
1536 case LOOP_CLR_FD:
1537 return loop_clr_fd(lo);
1538 case LOOP_SET_STATUS:
1539 err = -EPERM;
1540 if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN))
1541 err = loop_set_status_old(lo, argp);
1542 break;
1543 case LOOP_GET_STATUS:
1544 return loop_get_status_old(lo, argp);
1545 case LOOP_SET_STATUS64:
1546 err = -EPERM;
1547 if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN))
1548 err = loop_set_status64(lo, argp);
1549 break;
1550 case LOOP_GET_STATUS64:
1551 return loop_get_status64(lo, argp);
1552 case LOOP_SET_CAPACITY:
1553 case LOOP_SET_DIRECT_IO:
1554 case LOOP_SET_BLOCK_SIZE:
1555 if (!(mode & BLK_OPEN_WRITE) && !capable(CAP_SYS_ADMIN))
1556 return -EPERM;
1557 fallthrough;
1558 default:
1559 err = lo_simple_ioctl(lo, cmd, arg);
1560 break;
1561 }
1562
1563 return err;
1564}
1565
1566#ifdef CONFIG_COMPAT
1567struct compat_loop_info {
1568 compat_int_t lo_number; /* ioctl r/o */
1569 compat_dev_t lo_device; /* ioctl r/o */
1570 compat_ulong_t lo_inode; /* ioctl r/o */
1571 compat_dev_t lo_rdevice; /* ioctl r/o */
1572 compat_int_t lo_offset;
1573 compat_int_t lo_encrypt_type; /* obsolete, ignored */
1574 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1575 compat_int_t lo_flags; /* ioctl r/o */
1576 char lo_name[LO_NAME_SIZE];
1577 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1578 compat_ulong_t lo_init[2];
1579 char reserved[4];
1580};
1581
1582/*
1583 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1584 * - noinlined to reduce stack space usage in main part of driver
1585 */
1586static noinline int
1587loop_info64_from_compat(const struct compat_loop_info __user *arg,
1588 struct loop_info64 *info64)
1589{
1590 struct compat_loop_info info;
1591
1592 if (copy_from_user(&info, arg, sizeof(info)))
1593 return -EFAULT;
1594
1595 memset(info64, 0, sizeof(*info64));
1596 info64->lo_number = info.lo_number;
1597 info64->lo_device = info.lo_device;
1598 info64->lo_inode = info.lo_inode;
1599 info64->lo_rdevice = info.lo_rdevice;
1600 info64->lo_offset = info.lo_offset;
1601 info64->lo_sizelimit = 0;
1602 info64->lo_flags = info.lo_flags;
1603 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1604 return 0;
1605}
1606
1607/*
1608 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1609 * - noinlined to reduce stack space usage in main part of driver
1610 */
1611static noinline int
1612loop_info64_to_compat(const struct loop_info64 *info64,
1613 struct compat_loop_info __user *arg)
1614{
1615 struct compat_loop_info info;
1616
1617 memset(&info, 0, sizeof(info));
1618 info.lo_number = info64->lo_number;
1619 info.lo_device = info64->lo_device;
1620 info.lo_inode = info64->lo_inode;
1621 info.lo_rdevice = info64->lo_rdevice;
1622 info.lo_offset = info64->lo_offset;
1623 info.lo_flags = info64->lo_flags;
1624 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1625
1626 /* error in case values were truncated */
1627 if (info.lo_device != info64->lo_device ||
1628 info.lo_rdevice != info64->lo_rdevice ||
1629 info.lo_inode != info64->lo_inode ||
1630 info.lo_offset != info64->lo_offset)
1631 return -EOVERFLOW;
1632
1633 if (copy_to_user(arg, &info, sizeof(info)))
1634 return -EFAULT;
1635 return 0;
1636}
1637
1638static int
1639loop_set_status_compat(struct loop_device *lo,
1640 const struct compat_loop_info __user *arg)
1641{
1642 struct loop_info64 info64;
1643 int ret;
1644
1645 ret = loop_info64_from_compat(arg, &info64);
1646 if (ret < 0)
1647 return ret;
1648 return loop_set_status(lo, &info64);
1649}
1650
1651static int
1652loop_get_status_compat(struct loop_device *lo,
1653 struct compat_loop_info __user *arg)
1654{
1655 struct loop_info64 info64;
1656 int err;
1657
1658 if (!arg)
1659 return -EINVAL;
1660 err = loop_get_status(lo, &info64);
1661 if (!err)
1662 err = loop_info64_to_compat(&info64, arg);
1663 return err;
1664}
1665
1666static int lo_compat_ioctl(struct block_device *bdev, blk_mode_t mode,
1667 unsigned int cmd, unsigned long arg)
1668{
1669 struct loop_device *lo = bdev->bd_disk->private_data;
1670 int err;
1671
1672 switch(cmd) {
1673 case LOOP_SET_STATUS:
1674 err = loop_set_status_compat(lo,
1675 (const struct compat_loop_info __user *)arg);
1676 break;
1677 case LOOP_GET_STATUS:
1678 err = loop_get_status_compat(lo,
1679 (struct compat_loop_info __user *)arg);
1680 break;
1681 case LOOP_SET_CAPACITY:
1682 case LOOP_CLR_FD:
1683 case LOOP_GET_STATUS64:
1684 case LOOP_SET_STATUS64:
1685 case LOOP_CONFIGURE:
1686 arg = (unsigned long) compat_ptr(arg);
1687 fallthrough;
1688 case LOOP_SET_FD:
1689 case LOOP_CHANGE_FD:
1690 case LOOP_SET_BLOCK_SIZE:
1691 case LOOP_SET_DIRECT_IO:
1692 err = lo_ioctl(bdev, mode, cmd, arg);
1693 break;
1694 default:
1695 err = -ENOIOCTLCMD;
1696 break;
1697 }
1698 return err;
1699}
1700#endif
1701
1702static int lo_open(struct gendisk *disk, blk_mode_t mode)
1703{
1704 struct loop_device *lo = disk->private_data;
1705 int err;
1706
1707 err = mutex_lock_killable(&lo->lo_mutex);
1708 if (err)
1709 return err;
1710
1711 if (lo->lo_state == Lo_deleting || lo->lo_state == Lo_rundown)
1712 err = -ENXIO;
1713 mutex_unlock(&lo->lo_mutex);
1714 return err;
1715}
1716
1717static void lo_release(struct gendisk *disk)
1718{
1719 struct loop_device *lo = disk->private_data;
1720 bool need_clear = false;
1721
1722 if (disk_openers(disk) > 0)
1723 return;
1724 /*
1725 * Clear the backing device information if this is the last close of
1726 * a device that's been marked for auto clear, or on which LOOP_CLR_FD
1727 * has been called.
1728 */
1729
1730 mutex_lock(&lo->lo_mutex);
1731 if (lo->lo_state == Lo_bound && (lo->lo_flags & LO_FLAGS_AUTOCLEAR))
1732 lo->lo_state = Lo_rundown;
1733
1734 need_clear = (lo->lo_state == Lo_rundown);
1735 mutex_unlock(&lo->lo_mutex);
1736
1737 if (need_clear)
1738 __loop_clr_fd(lo);
1739}
1740
1741static void lo_free_disk(struct gendisk *disk)
1742{
1743 struct loop_device *lo = disk->private_data;
1744
1745 if (lo->workqueue)
1746 destroy_workqueue(lo->workqueue);
1747 loop_free_idle_workers(lo, true);
1748 timer_shutdown_sync(&lo->timer);
1749 mutex_destroy(&lo->lo_mutex);
1750 kfree(lo);
1751}
1752
1753static const struct block_device_operations lo_fops = {
1754 .owner = THIS_MODULE,
1755 .open = lo_open,
1756 .release = lo_release,
1757 .ioctl = lo_ioctl,
1758#ifdef CONFIG_COMPAT
1759 .compat_ioctl = lo_compat_ioctl,
1760#endif
1761 .free_disk = lo_free_disk,
1762};
1763
1764/*
1765 * And now the modules code and kernel interface.
1766 */
1767
1768/*
1769 * If max_loop is specified, create that many devices upfront.
1770 * This also becomes a hard limit. If max_loop is not specified,
1771 * the default isn't a hard limit (as before commit 85c50197716c
1772 * changed the default value from 0 for max_loop=0 reasons), just
1773 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1774 * init time. Loop devices can be requested on-demand with the
1775 * /dev/loop-control interface, or be instantiated by accessing
1776 * a 'dead' device node.
1777 */
1778static int max_loop = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1779
1780#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
1781static bool max_loop_specified;
1782
1783static int max_loop_param_set_int(const char *val,
1784 const struct kernel_param *kp)
1785{
1786 int ret;
1787
1788 ret = param_set_int(val, kp);
1789 if (ret < 0)
1790 return ret;
1791
1792 max_loop_specified = true;
1793 return 0;
1794}
1795
1796static const struct kernel_param_ops max_loop_param_ops = {
1797 .set = max_loop_param_set_int,
1798 .get = param_get_int,
1799};
1800
1801module_param_cb(max_loop, &max_loop_param_ops, &max_loop, 0444);
1802MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1803#else
1804module_param(max_loop, int, 0444);
1805MODULE_PARM_DESC(max_loop, "Initial number of loop devices");
1806#endif
1807
1808module_param(max_part, int, 0444);
1809MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1810
1811static int hw_queue_depth = LOOP_DEFAULT_HW_Q_DEPTH;
1812
1813static int loop_set_hw_queue_depth(const char *s, const struct kernel_param *p)
1814{
1815 int qd, ret;
1816
1817 ret = kstrtoint(s, 0, &qd);
1818 if (ret < 0)
1819 return ret;
1820 if (qd < 1)
1821 return -EINVAL;
1822 hw_queue_depth = qd;
1823 return 0;
1824}
1825
1826static const struct kernel_param_ops loop_hw_qdepth_param_ops = {
1827 .set = loop_set_hw_queue_depth,
1828 .get = param_get_int,
1829};
1830
1831device_param_cb(hw_queue_depth, &loop_hw_qdepth_param_ops, &hw_queue_depth, 0444);
1832MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: " __stringify(LOOP_DEFAULT_HW_Q_DEPTH));
1833
1834MODULE_DESCRIPTION("Loopback device support");
1835MODULE_LICENSE("GPL");
1836MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1837
1838static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
1839 const struct blk_mq_queue_data *bd)
1840{
1841 struct request *rq = bd->rq;
1842 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
1843 struct loop_device *lo = rq->q->queuedata;
1844
1845 blk_mq_start_request(rq);
1846
1847 if (lo->lo_state != Lo_bound)
1848 return BLK_STS_IOERR;
1849
1850 switch (req_op(rq)) {
1851 case REQ_OP_FLUSH:
1852 case REQ_OP_DISCARD:
1853 case REQ_OP_WRITE_ZEROES:
1854 cmd->use_aio = false;
1855 break;
1856 default:
1857 cmd->use_aio = lo->use_dio;
1858 break;
1859 }
1860
1861 /* always use the first bio's css */
1862 cmd->blkcg_css = NULL;
1863 cmd->memcg_css = NULL;
1864#ifdef CONFIG_BLK_CGROUP
1865 if (rq->bio) {
1866 cmd->blkcg_css = bio_blkcg_css(rq->bio);
1867#ifdef CONFIG_MEMCG
1868 if (cmd->blkcg_css) {
1869 cmd->memcg_css =
1870 cgroup_get_e_css(cmd->blkcg_css->cgroup,
1871 &memory_cgrp_subsys);
1872 }
1873#endif
1874 }
1875#endif
1876 loop_queue_work(lo, cmd);
1877
1878 return BLK_STS_OK;
1879}
1880
1881static void loop_handle_cmd(struct loop_cmd *cmd)
1882{
1883 struct cgroup_subsys_state *cmd_blkcg_css = cmd->blkcg_css;
1884 struct cgroup_subsys_state *cmd_memcg_css = cmd->memcg_css;
1885 struct request *rq = blk_mq_rq_from_pdu(cmd);
1886 const bool write = op_is_write(req_op(rq));
1887 struct loop_device *lo = rq->q->queuedata;
1888 int ret = 0;
1889 struct mem_cgroup *old_memcg = NULL;
1890 const bool use_aio = cmd->use_aio;
1891
1892 if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) {
1893 ret = -EIO;
1894 goto failed;
1895 }
1896
1897 if (cmd_blkcg_css)
1898 kthread_associate_blkcg(cmd_blkcg_css);
1899 if (cmd_memcg_css)
1900 old_memcg = set_active_memcg(
1901 mem_cgroup_from_css(cmd_memcg_css));
1902
1903 /*
1904 * do_req_filebacked() may call blk_mq_complete_request() synchronously
1905 * or asynchronously if using aio. Hence, do not touch 'cmd' after
1906 * do_req_filebacked() has returned unless we are sure that 'cmd' has
1907 * not yet been completed.
1908 */
1909 ret = do_req_filebacked(lo, rq);
1910
1911 if (cmd_blkcg_css)
1912 kthread_associate_blkcg(NULL);
1913
1914 if (cmd_memcg_css) {
1915 set_active_memcg(old_memcg);
1916 css_put(cmd_memcg_css);
1917 }
1918 failed:
1919 /* complete non-aio request */
1920 if (!use_aio || ret) {
1921 if (ret == -EOPNOTSUPP)
1922 cmd->ret = ret;
1923 else
1924 cmd->ret = ret ? -EIO : 0;
1925 if (likely(!blk_should_fake_timeout(rq->q)))
1926 blk_mq_complete_request(rq);
1927 }
1928}
1929
1930static void loop_process_work(struct loop_worker *worker,
1931 struct list_head *cmd_list, struct loop_device *lo)
1932{
1933 int orig_flags = current->flags;
1934 struct loop_cmd *cmd;
1935
1936 current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO;
1937 spin_lock_irq(&lo->lo_work_lock);
1938 while (!list_empty(cmd_list)) {
1939 cmd = container_of(
1940 cmd_list->next, struct loop_cmd, list_entry);
1941 list_del(cmd_list->next);
1942 spin_unlock_irq(&lo->lo_work_lock);
1943
1944 loop_handle_cmd(cmd);
1945 cond_resched();
1946
1947 spin_lock_irq(&lo->lo_work_lock);
1948 }
1949
1950 /*
1951 * We only add to the idle list if there are no pending cmds
1952 * *and* the worker will not run again which ensures that it
1953 * is safe to free any worker on the idle list
1954 */
1955 if (worker && !work_pending(&worker->work)) {
1956 worker->last_ran_at = jiffies;
1957 list_add_tail(&worker->idle_list, &lo->idle_worker_list);
1958 loop_set_timer(lo);
1959 }
1960 spin_unlock_irq(&lo->lo_work_lock);
1961 current->flags = orig_flags;
1962}
1963
1964static void loop_workfn(struct work_struct *work)
1965{
1966 struct loop_worker *worker =
1967 container_of(work, struct loop_worker, work);
1968 loop_process_work(worker, &worker->cmd_list, worker->lo);
1969}
1970
1971static void loop_rootcg_workfn(struct work_struct *work)
1972{
1973 struct loop_device *lo =
1974 container_of(work, struct loop_device, rootcg_work);
1975 loop_process_work(NULL, &lo->rootcg_cmd_list, lo);
1976}
1977
1978static const struct blk_mq_ops loop_mq_ops = {
1979 .queue_rq = loop_queue_rq,
1980 .complete = lo_complete_rq,
1981};
1982
1983static int loop_add(int i)
1984{
1985 struct queue_limits lim = {
1986 /*
1987 * Random number picked from the historic block max_sectors cap.
1988 */
1989 .max_hw_sectors = 2560u,
1990 };
1991 struct loop_device *lo;
1992 struct gendisk *disk;
1993 int err;
1994
1995 err = -ENOMEM;
1996 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1997 if (!lo)
1998 goto out;
1999 lo->worker_tree = RB_ROOT;
2000 INIT_LIST_HEAD(&lo->idle_worker_list);
2001 timer_setup(&lo->timer, loop_free_idle_workers_timer, TIMER_DEFERRABLE);
2002 lo->lo_state = Lo_unbound;
2003
2004 err = mutex_lock_killable(&loop_ctl_mutex);
2005 if (err)
2006 goto out_free_dev;
2007
2008 /* allocate id, if @id >= 0, we're requesting that specific id */
2009 if (i >= 0) {
2010 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
2011 if (err == -ENOSPC)
2012 err = -EEXIST;
2013 } else {
2014 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
2015 }
2016 mutex_unlock(&loop_ctl_mutex);
2017 if (err < 0)
2018 goto out_free_dev;
2019 i = err;
2020
2021 lo->tag_set.ops = &loop_mq_ops;
2022 lo->tag_set.nr_hw_queues = 1;
2023 lo->tag_set.queue_depth = hw_queue_depth;
2024 lo->tag_set.numa_node = NUMA_NO_NODE;
2025 lo->tag_set.cmd_size = sizeof(struct loop_cmd);
2026 lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING |
2027 BLK_MQ_F_NO_SCHED_BY_DEFAULT;
2028 lo->tag_set.driver_data = lo;
2029
2030 err = blk_mq_alloc_tag_set(&lo->tag_set);
2031 if (err)
2032 goto out_free_idr;
2033
2034 disk = lo->lo_disk = blk_mq_alloc_disk(&lo->tag_set, &lim, lo);
2035 if (IS_ERR(disk)) {
2036 err = PTR_ERR(disk);
2037 goto out_cleanup_tags;
2038 }
2039 lo->lo_queue = lo->lo_disk->queue;
2040
2041 /*
2042 * Disable partition scanning by default. The in-kernel partition
2043 * scanning can be requested individually per-device during its
2044 * setup. Userspace can always add and remove partitions from all
2045 * devices. The needed partition minors are allocated from the
2046 * extended minor space, the main loop device numbers will continue
2047 * to match the loop minors, regardless of the number of partitions
2048 * used.
2049 *
2050 * If max_part is given, partition scanning is globally enabled for
2051 * all loop devices. The minors for the main loop devices will be
2052 * multiples of max_part.
2053 *
2054 * Note: Global-for-all-devices, set-only-at-init, read-only module
2055 * parameteters like 'max_loop' and 'max_part' make things needlessly
2056 * complicated, are too static, inflexible and may surprise
2057 * userspace tools. Parameters like this in general should be avoided.
2058 */
2059 if (!part_shift)
2060 set_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
2061 mutex_init(&lo->lo_mutex);
2062 lo->lo_number = i;
2063 spin_lock_init(&lo->lo_lock);
2064 spin_lock_init(&lo->lo_work_lock);
2065 INIT_WORK(&lo->rootcg_work, loop_rootcg_workfn);
2066 INIT_LIST_HEAD(&lo->rootcg_cmd_list);
2067 disk->major = LOOP_MAJOR;
2068 disk->first_minor = i << part_shift;
2069 disk->minors = 1 << part_shift;
2070 disk->fops = &lo_fops;
2071 disk->private_data = lo;
2072 disk->queue = lo->lo_queue;
2073 disk->events = DISK_EVENT_MEDIA_CHANGE;
2074 disk->event_flags = DISK_EVENT_FLAG_UEVENT;
2075 sprintf(disk->disk_name, "loop%d", i);
2076 /* Make this loop device reachable from pathname. */
2077 err = add_disk(disk);
2078 if (err)
2079 goto out_cleanup_disk;
2080
2081 /* Show this loop device. */
2082 mutex_lock(&loop_ctl_mutex);
2083 lo->idr_visible = true;
2084 mutex_unlock(&loop_ctl_mutex);
2085
2086 return i;
2087
2088out_cleanup_disk:
2089 put_disk(disk);
2090out_cleanup_tags:
2091 blk_mq_free_tag_set(&lo->tag_set);
2092out_free_idr:
2093 mutex_lock(&loop_ctl_mutex);
2094 idr_remove(&loop_index_idr, i);
2095 mutex_unlock(&loop_ctl_mutex);
2096out_free_dev:
2097 kfree(lo);
2098out:
2099 return err;
2100}
2101
2102static void loop_remove(struct loop_device *lo)
2103{
2104 /* Make this loop device unreachable from pathname. */
2105 del_gendisk(lo->lo_disk);
2106 blk_mq_free_tag_set(&lo->tag_set);
2107
2108 mutex_lock(&loop_ctl_mutex);
2109 idr_remove(&loop_index_idr, lo->lo_number);
2110 mutex_unlock(&loop_ctl_mutex);
2111
2112 put_disk(lo->lo_disk);
2113}
2114
2115#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
2116static void loop_probe(dev_t dev)
2117{
2118 int idx = MINOR(dev) >> part_shift;
2119
2120 if (max_loop_specified && max_loop && idx >= max_loop)
2121 return;
2122 loop_add(idx);
2123}
2124#else
2125#define loop_probe NULL
2126#endif /* !CONFIG_BLOCK_LEGACY_AUTOLOAD */
2127
2128static int loop_control_remove(int idx)
2129{
2130 struct loop_device *lo;
2131 int ret;
2132
2133 if (idx < 0) {
2134 pr_warn_once("deleting an unspecified loop device is not supported.\n");
2135 return -EINVAL;
2136 }
2137
2138 /* Hide this loop device for serialization. */
2139 ret = mutex_lock_killable(&loop_ctl_mutex);
2140 if (ret)
2141 return ret;
2142 lo = idr_find(&loop_index_idr, idx);
2143 if (!lo || !lo->idr_visible)
2144 ret = -ENODEV;
2145 else
2146 lo->idr_visible = false;
2147 mutex_unlock(&loop_ctl_mutex);
2148 if (ret)
2149 return ret;
2150
2151 /* Check whether this loop device can be removed. */
2152 ret = mutex_lock_killable(&lo->lo_mutex);
2153 if (ret)
2154 goto mark_visible;
2155 if (lo->lo_state != Lo_unbound || disk_openers(lo->lo_disk) > 0) {
2156 mutex_unlock(&lo->lo_mutex);
2157 ret = -EBUSY;
2158 goto mark_visible;
2159 }
2160 /* Mark this loop device as no more bound, but not quite unbound yet */
2161 lo->lo_state = Lo_deleting;
2162 mutex_unlock(&lo->lo_mutex);
2163
2164 loop_remove(lo);
2165 return 0;
2166
2167mark_visible:
2168 /* Show this loop device again. */
2169 mutex_lock(&loop_ctl_mutex);
2170 lo->idr_visible = true;
2171 mutex_unlock(&loop_ctl_mutex);
2172 return ret;
2173}
2174
2175static int loop_control_get_free(int idx)
2176{
2177 struct loop_device *lo;
2178 int id, ret;
2179
2180 ret = mutex_lock_killable(&loop_ctl_mutex);
2181 if (ret)
2182 return ret;
2183 idr_for_each_entry(&loop_index_idr, lo, id) {
2184 /* Hitting a race results in creating a new loop device which is harmless. */
2185 if (lo->idr_visible && data_race(lo->lo_state) == Lo_unbound)
2186 goto found;
2187 }
2188 mutex_unlock(&loop_ctl_mutex);
2189 return loop_add(-1);
2190found:
2191 mutex_unlock(&loop_ctl_mutex);
2192 return id;
2193}
2194
2195static long loop_control_ioctl(struct file *file, unsigned int cmd,
2196 unsigned long parm)
2197{
2198 switch (cmd) {
2199 case LOOP_CTL_ADD:
2200 return loop_add(parm);
2201 case LOOP_CTL_REMOVE:
2202 return loop_control_remove(parm);
2203 case LOOP_CTL_GET_FREE:
2204 return loop_control_get_free(parm);
2205 default:
2206 return -ENOSYS;
2207 }
2208}
2209
2210static const struct file_operations loop_ctl_fops = {
2211 .open = nonseekable_open,
2212 .unlocked_ioctl = loop_control_ioctl,
2213 .compat_ioctl = loop_control_ioctl,
2214 .owner = THIS_MODULE,
2215 .llseek = noop_llseek,
2216};
2217
2218static struct miscdevice loop_misc = {
2219 .minor = LOOP_CTRL_MINOR,
2220 .name = "loop-control",
2221 .fops = &loop_ctl_fops,
2222};
2223
2224MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
2225MODULE_ALIAS("devname:loop-control");
2226
2227static int __init loop_init(void)
2228{
2229 int i;
2230 int err;
2231
2232 part_shift = 0;
2233 if (max_part > 0) {
2234 part_shift = fls(max_part);
2235
2236 /*
2237 * Adjust max_part according to part_shift as it is exported
2238 * to user space so that user can decide correct minor number
2239 * if [s]he want to create more devices.
2240 *
2241 * Note that -1 is required because partition 0 is reserved
2242 * for the whole disk.
2243 */
2244 max_part = (1UL << part_shift) - 1;
2245 }
2246
2247 if ((1UL << part_shift) > DISK_MAX_PARTS) {
2248 err = -EINVAL;
2249 goto err_out;
2250 }
2251
2252 if (max_loop > 1UL << (MINORBITS - part_shift)) {
2253 err = -EINVAL;
2254 goto err_out;
2255 }
2256
2257 err = misc_register(&loop_misc);
2258 if (err < 0)
2259 goto err_out;
2260
2261
2262 if (__register_blkdev(LOOP_MAJOR, "loop", loop_probe)) {
2263 err = -EIO;
2264 goto misc_out;
2265 }
2266
2267 /* pre-create number of devices given by config or max_loop */
2268 for (i = 0; i < max_loop; i++)
2269 loop_add(i);
2270
2271 printk(KERN_INFO "loop: module loaded\n");
2272 return 0;
2273
2274misc_out:
2275 misc_deregister(&loop_misc);
2276err_out:
2277 return err;
2278}
2279
2280static void __exit loop_exit(void)
2281{
2282 struct loop_device *lo;
2283 int id;
2284
2285 unregister_blkdev(LOOP_MAJOR, "loop");
2286 misc_deregister(&loop_misc);
2287
2288 /*
2289 * There is no need to use loop_ctl_mutex here, for nobody else can
2290 * access loop_index_idr when this module is unloading (unless forced
2291 * module unloading is requested). If this is not a clean unloading,
2292 * we have no means to avoid kernel crash.
2293 */
2294 idr_for_each_entry(&loop_index_idr, lo, id)
2295 loop_remove(lo);
2296
2297 idr_destroy(&loop_index_idr);
2298}
2299
2300module_init(loop_init);
2301module_exit(loop_exit);
2302
2303#ifndef MODULE
2304static int __init max_loop_setup(char *str)
2305{
2306 max_loop = simple_strtol(str, NULL, 0);
2307#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
2308 max_loop_specified = true;
2309#endif
2310 return 1;
2311}
2312
2313__setup("max_loop=", max_loop_setup);
2314#endif