projects/linux·blob v4.20 · refs

2167 lines · 52.9 KiB

1/*
2 * linux/drivers/block/loop.c
3 *
4 * Written by Theodore Ts'o, 3/29/93
5 *
6 * Copyright 1993 by Theodore Ts'o. Redistribution of this file is
7 * permitted under the GNU General Public License.
8 *
9 * DES encryption plus some minor changes by Werner Almesberger, 30-MAY-1993
10 * more DES encryption plus IDEA encryption by Nicholas J. Leon, June 20, 1996
11 *
12 * Modularized and updated for 1.1.16 kernel - Mitch Dsouza 28th May 1994
13 * Adapted for 1.3.59 kernel - Andries Brouwer, 1 Feb 1996
14 *
15 * Fixed do_loop_request() re-entrancy - [email protected] Mar 20, 1997
16 *
17 * Added devfs support - Richard Gooch <[email protected]> 16-Jan-1998
18 *
19 * Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998
20 *
21 * Loadable modules and other fixes by AK, 1998
22 *
23 * Make real block number available to downstream transfer functions, enables
24 * CBC (and relatives) mode encryption requiring unique IVs per data block.
25 * Reed H. Petty, [email protected]
26 *
27 * Maximum number of loop devices now dynamic via max_loop module parameter.
28 * Russell Kroll <[email protected]> 19990701
29 *
30 * Maximum number of loop devices when compiled-in now selectable by passing
31 * max_loop=<1-255> to the kernel on boot.
32 * Erik I. Bolsø, <[email protected]>, Oct 31, 1999
33 *
34 * Completely rewrite request handling to be make_request_fn style and
35 * non blocking, pushing work to a helper thread. Lots of fixes from
36 * Al Viro too.
37 * Jens Axboe <[email protected]>, Nov 2000
38 *
39 * Support up to 256 loop devices
40 * Heinz Mauelshagen <[email protected]>, Feb 2002
41 *
42 * Support for falling back on the write file operation when the address space
43 * operations write_begin is not available on the backing filesystem.
44 * Anton Altaparmakov, 16 Feb 2005
45 *
46 * Still To Fix:
47 * - Advisory locking is ignored here.
48 * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
49 *
50 */
51
52#include <linux/module.h>
53#include <linux/moduleparam.h>
54#include <linux/sched.h>
55#include <linux/fs.h>
56#include <linux/file.h>
57#include <linux/stat.h>
58#include <linux/errno.h>
59#include <linux/major.h>
60#include <linux/wait.h>
61#include <linux/blkdev.h>
62#include <linux/blkpg.h>
63#include <linux/init.h>
64#include <linux/swap.h>
65#include <linux/slab.h>
66#include <linux/compat.h>
67#include <linux/suspend.h>
68#include <linux/freezer.h>
69#include <linux/mutex.h>
70#include <linux/writeback.h>
71#include <linux/completion.h>
72#include <linux/highmem.h>
73#include <linux/kthread.h>
74#include <linux/splice.h>
75#include <linux/sysfs.h>
76#include <linux/miscdevice.h>
77#include <linux/falloc.h>
78#include <linux/uio.h>
79#include <linux/ioprio.h>
80
81#include "loop.h"
82
83#include <linux/uaccess.h>
84
85static DEFINE_IDR(loop_index_idr);
86static DEFINE_MUTEX(loop_index_mutex);
87
88static int max_part;
89static int part_shift;
90
91static int transfer_xor(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 char *in, *out, *key;
99 int i, keysize;
100
101 if (cmd == READ) {
102 in = raw_buf;
103 out = loop_buf;
104 } else {
105 in = loop_buf;
106 out = raw_buf;
107 }
108
109 key = lo->lo_encrypt_key;
110 keysize = lo->lo_encrypt_key_size;
111 for (i = 0; i < size; i++)
112 *out++ = *in++ ^ key[(i & 511) % keysize];
113
114 kunmap_atomic(loop_buf);
115 kunmap_atomic(raw_buf);
116 cond_resched();
117 return 0;
118}
119
120static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
121{
122 if (unlikely(info->lo_encrypt_key_size <= 0))
123 return -EINVAL;
124 return 0;
125}
126
127static struct loop_func_table none_funcs = {
128 .number = LO_CRYPT_NONE,
129};
130
131static struct loop_func_table xor_funcs = {
132 .number = LO_CRYPT_XOR,
133 .transfer = transfer_xor,
134 .init = xor_init
135};
136
137/* xfer_funcs[0] is special - its release function is never called */
138static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
139 &none_funcs,
140 &xor_funcs
141};
142
143static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
144{
145 loff_t loopsize;
146
147 /* Compute loopsize in bytes */
148 loopsize = i_size_read(file->f_mapping->host);
149 if (offset > 0)
150 loopsize -= offset;
151 /* offset is beyond i_size, weird but possible */
152 if (loopsize < 0)
153 return 0;
154
155 if (sizelimit > 0 && sizelimit < loopsize)
156 loopsize = sizelimit;
157 /*
158 * Unfortunately, if we want to do I/O on the device,
159 * the number of 512-byte sectors has to fit into a sector_t.
160 */
161 return loopsize >> 9;
162}
163
164static loff_t get_loop_size(struct loop_device *lo, struct file *file)
165{
166 return get_size(lo->lo_offset, lo->lo_sizelimit, file);
167}
168
169static void __loop_update_dio(struct loop_device *lo, bool dio)
170{
171 struct file *file = lo->lo_backing_file;
172 struct address_space *mapping = file->f_mapping;
173 struct inode *inode = mapping->host;
174 unsigned short sb_bsize = 0;
175 unsigned dio_align = 0;
176 bool use_dio;
177
178 if (inode->i_sb->s_bdev) {
179 sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
180 dio_align = sb_bsize - 1;
181 }
182
183 /*
184 * We support direct I/O only if lo_offset is aligned with the
185 * logical I/O size of backing device, and the logical block
186 * size of loop is bigger than the backing device's and the loop
187 * needn't transform transfer.
188 *
189 * TODO: the above condition may be loosed in the future, and
190 * direct I/O may be switched runtime at that time because most
191 * of requests in sane applications should be PAGE_SIZE aligned
192 */
193 if (dio) {
194 if (queue_logical_block_size(lo->lo_queue) >= sb_bsize &&
195 !(lo->lo_offset & dio_align) &&
196 mapping->a_ops->direct_IO &&
197 !lo->transfer)
198 use_dio = true;
199 else
200 use_dio = false;
201 } else {
202 use_dio = false;
203 }
204
205 if (lo->use_dio == use_dio)
206 return;
207
208 /* flush dirty pages before changing direct IO */
209 vfs_fsync(file, 0);
210
211 /*
212 * The flag of LO_FLAGS_DIRECT_IO is handled similarly with
213 * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup
214 * will get updated by ioctl(LOOP_GET_STATUS)
215 */
216 blk_mq_freeze_queue(lo->lo_queue);
217 lo->use_dio = use_dio;
218 if (use_dio) {
219 blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, lo->lo_queue);
220 lo->lo_flags |= LO_FLAGS_DIRECT_IO;
221 } else {
222 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
223 lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
224 }
225 blk_mq_unfreeze_queue(lo->lo_queue);
226}
227
228static int
229figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
230{
231 loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
232 sector_t x = (sector_t)size;
233 struct block_device *bdev = lo->lo_device;
234
235 if (unlikely((loff_t)x != size))
236 return -EFBIG;
237 if (lo->lo_offset != offset)
238 lo->lo_offset = offset;
239 if (lo->lo_sizelimit != sizelimit)
240 lo->lo_sizelimit = sizelimit;
241 set_capacity(lo->lo_disk, x);
242 bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
243 /* let user-space know about the new size */
244 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
245 return 0;
246}
247
248static inline int
249lo_do_transfer(struct loop_device *lo, int cmd,
250 struct page *rpage, unsigned roffs,
251 struct page *lpage, unsigned loffs,
252 int size, sector_t rblock)
253{
254 int ret;
255
256 ret = lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
257 if (likely(!ret))
258 return 0;
259
260 printk_ratelimited(KERN_ERR
261 "loop: Transfer error at byte offset %llu, length %i.\n",
262 (unsigned long long)rblock << 9, size);
263 return ret;
264}
265
266static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)
267{
268 struct iov_iter i;
269 ssize_t bw;
270
271 iov_iter_bvec(&i, WRITE, bvec, 1, bvec->bv_len);
272
273 file_start_write(file);
274 bw = vfs_iter_write(file, &i, ppos, 0);
275 file_end_write(file);
276
277 if (likely(bw == bvec->bv_len))
278 return 0;
279
280 printk_ratelimited(KERN_ERR
281 "loop: Write error at byte offset %llu, length %i.\n",
282 (unsigned long long)*ppos, bvec->bv_len);
283 if (bw >= 0)
284 bw = -EIO;
285 return bw;
286}
287
288static int lo_write_simple(struct loop_device *lo, struct request *rq,
289 loff_t pos)
290{
291 struct bio_vec bvec;
292 struct req_iterator iter;
293 int ret = 0;
294
295 rq_for_each_segment(bvec, rq, iter) {
296 ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
297 if (ret < 0)
298 break;
299 cond_resched();
300 }
301
302 return ret;
303}
304
305/*
306 * This is the slow, transforming version that needs to double buffer the
307 * data as it cannot do the transformations in place without having direct
308 * access to the destination pages of the backing file.
309 */
310static int lo_write_transfer(struct loop_device *lo, struct request *rq,
311 loff_t pos)
312{
313 struct bio_vec bvec, b;
314 struct req_iterator iter;
315 struct page *page;
316 int ret = 0;
317
318 page = alloc_page(GFP_NOIO);
319 if (unlikely(!page))
320 return -ENOMEM;
321
322 rq_for_each_segment(bvec, rq, iter) {
323 ret = lo_do_transfer(lo, WRITE, page, 0, bvec.bv_page,
324 bvec.bv_offset, bvec.bv_len, pos >> 9);
325 if (unlikely(ret))
326 break;
327
328 b.bv_page = page;
329 b.bv_offset = 0;
330 b.bv_len = bvec.bv_len;
331 ret = lo_write_bvec(lo->lo_backing_file, &b, &pos);
332 if (ret < 0)
333 break;
334 }
335
336 __free_page(page);
337 return ret;
338}
339
340static int lo_read_simple(struct loop_device *lo, struct request *rq,
341 loff_t pos)
342{
343 struct bio_vec bvec;
344 struct req_iterator iter;
345 struct iov_iter i;
346 ssize_t len;
347
348 rq_for_each_segment(bvec, rq, iter) {
349 iov_iter_bvec(&i, READ, &bvec, 1, bvec.bv_len);
350 len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);
351 if (len < 0)
352 return len;
353
354 flush_dcache_page(bvec.bv_page);
355
356 if (len != bvec.bv_len) {
357 struct bio *bio;
358
359 __rq_for_each_bio(bio, rq)
360 zero_fill_bio(bio);
361 break;
362 }
363 cond_resched();
364 }
365
366 return 0;
367}
368
369static int lo_read_transfer(struct loop_device *lo, struct request *rq,
370 loff_t pos)
371{
372 struct bio_vec bvec, b;
373 struct req_iterator iter;
374 struct iov_iter i;
375 struct page *page;
376 ssize_t len;
377 int ret = 0;
378
379 page = alloc_page(GFP_NOIO);
380 if (unlikely(!page))
381 return -ENOMEM;
382
383 rq_for_each_segment(bvec, rq, iter) {
384 loff_t offset = pos;
385
386 b.bv_page = page;
387 b.bv_offset = 0;
388 b.bv_len = bvec.bv_len;
389
390 iov_iter_bvec(&i, READ, &b, 1, b.bv_len);
391 len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);
392 if (len < 0) {
393 ret = len;
394 goto out_free_page;
395 }
396
397 ret = lo_do_transfer(lo, READ, page, 0, bvec.bv_page,
398 bvec.bv_offset, len, offset >> 9);
399 if (ret)
400 goto out_free_page;
401
402 flush_dcache_page(bvec.bv_page);
403
404 if (len != bvec.bv_len) {
405 struct bio *bio;
406
407 __rq_for_each_bio(bio, rq)
408 zero_fill_bio(bio);
409 break;
410 }
411 }
412
413 ret = 0;
414out_free_page:
415 __free_page(page);
416 return ret;
417}
418
419static int lo_discard(struct loop_device *lo, struct request *rq, loff_t pos)
420{
421 /*
422 * We use punch hole to reclaim the free space used by the
423 * image a.k.a. discard. However we do not support discard if
424 * encryption is enabled, because it may give an attacker
425 * useful information.
426 */
427 struct file *file = lo->lo_backing_file;
428 int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
429 int ret;
430
431 if ((!file->f_op->fallocate) || lo->lo_encrypt_key_size) {
432 ret = -EOPNOTSUPP;
433 goto out;
434 }
435
436 ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
437 if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
438 ret = -EIO;
439 out:
440 return ret;
441}
442
443static int lo_req_flush(struct loop_device *lo, struct request *rq)
444{
445 struct file *file = lo->lo_backing_file;
446 int ret = vfs_fsync(file, 0);
447 if (unlikely(ret && ret != -EINVAL))
448 ret = -EIO;
449
450 return ret;
451}
452
453static void lo_complete_rq(struct request *rq)
454{
455 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
456 blk_status_t ret = BLK_STS_OK;
457
458 if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) ||
459 req_op(rq) != REQ_OP_READ) {
460 if (cmd->ret < 0)
461 ret = BLK_STS_IOERR;
462 goto end_io;
463 }
464
465 /*
466 * Short READ - if we got some data, advance our request and
467 * retry it. If we got no data, end the rest with EIO.
468 */
469 if (cmd->ret) {
470 blk_update_request(rq, BLK_STS_OK, cmd->ret);
471 cmd->ret = 0;
472 blk_mq_requeue_request(rq, true);
473 } else {
474 if (cmd->use_aio) {
475 struct bio *bio = rq->bio;
476
477 while (bio) {
478 zero_fill_bio(bio);
479 bio = bio->bi_next;
480 }
481 }
482 ret = BLK_STS_IOERR;
483end_io:
484 blk_mq_end_request(rq, ret);
485 }
486}
487
488static void lo_rw_aio_do_completion(struct loop_cmd *cmd)
489{
490 struct request *rq = blk_mq_rq_from_pdu(cmd);
491
492 if (!atomic_dec_and_test(&cmd->ref))
493 return;
494 kfree(cmd->bvec);
495 cmd->bvec = NULL;
496 blk_mq_complete_request(rq);
497}
498
499static void lo_rw_aio_complete(struct kiocb *iocb, long ret, long ret2)
500{
501 struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb);
502
503 if (cmd->css)
504 css_put(cmd->css);
505 cmd->ret = ret;
506 lo_rw_aio_do_completion(cmd);
507}
508
509static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
510 loff_t pos, bool rw)
511{
512 struct iov_iter iter;
513 struct bio_vec *bvec;
514 struct request *rq = blk_mq_rq_from_pdu(cmd);
515 struct bio *bio = rq->bio;
516 struct file *file = lo->lo_backing_file;
517 unsigned int offset;
518 int segments = 0;
519 int ret;
520
521 if (rq->bio != rq->biotail) {
522 struct req_iterator iter;
523 struct bio_vec tmp;
524
525 __rq_for_each_bio(bio, rq)
526 segments += bio_segments(bio);
527 bvec = kmalloc_array(segments, sizeof(struct bio_vec),
528 GFP_NOIO);
529 if (!bvec)
530 return -EIO;
531 cmd->bvec = bvec;
532
533 /*
534 * The bios of the request may be started from the middle of
535 * the 'bvec' because of bio splitting, so we can't directly
536 * copy bio->bi_iov_vec to new bvec. The rq_for_each_segment
537 * API will take care of all details for us.
538 */
539 rq_for_each_segment(tmp, rq, iter) {
540 *bvec = tmp;
541 bvec++;
542 }
543 bvec = cmd->bvec;
544 offset = 0;
545 } else {
546 /*
547 * Same here, this bio may be started from the middle of the
548 * 'bvec' because of bio splitting, so offset from the bvec
549 * must be passed to iov iterator
550 */
551 offset = bio->bi_iter.bi_bvec_done;
552 bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
553 segments = bio_segments(bio);
554 }
555 atomic_set(&cmd->ref, 2);
556
557 iov_iter_bvec(&iter, rw, bvec, segments, blk_rq_bytes(rq));
558 iter.iov_offset = offset;
559
560 cmd->iocb.ki_pos = pos;
561 cmd->iocb.ki_filp = file;
562 cmd->iocb.ki_complete = lo_rw_aio_complete;
563 cmd->iocb.ki_flags = IOCB_DIRECT;
564 cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
565 if (cmd->css)
566 kthread_associate_blkcg(cmd->css);
567
568 if (rw == WRITE)
569 ret = call_write_iter(file, &cmd->iocb, &iter);
570 else
571 ret = call_read_iter(file, &cmd->iocb, &iter);
572
573 lo_rw_aio_do_completion(cmd);
574 kthread_associate_blkcg(NULL);
575
576 if (ret != -EIOCBQUEUED)
577 cmd->iocb.ki_complete(&cmd->iocb, ret, 0);
578 return 0;
579}
580
581static int do_req_filebacked(struct loop_device *lo, struct request *rq)
582{
583 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
584 loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
585
586 /*
587 * lo_write_simple and lo_read_simple should have been covered
588 * by io submit style function like lo_rw_aio(), one blocker
589 * is that lo_read_simple() need to call flush_dcache_page after
590 * the page is written from kernel, and it isn't easy to handle
591 * this in io submit style function which submits all segments
592 * of the req at one time. And direct read IO doesn't need to
593 * run flush_dcache_page().
594 */
595 switch (req_op(rq)) {
596 case REQ_OP_FLUSH:
597 return lo_req_flush(lo, rq);
598 case REQ_OP_DISCARD:
599 case REQ_OP_WRITE_ZEROES:
600 return lo_discard(lo, rq, pos);
601 case REQ_OP_WRITE:
602 if (lo->transfer)
603 return lo_write_transfer(lo, rq, pos);
604 else if (cmd->use_aio)
605 return lo_rw_aio(lo, cmd, pos, WRITE);
606 else
607 return lo_write_simple(lo, rq, pos);
608 case REQ_OP_READ:
609 if (lo->transfer)
610 return lo_read_transfer(lo, rq, pos);
611 else if (cmd->use_aio)
612 return lo_rw_aio(lo, cmd, pos, READ);
613 else
614 return lo_read_simple(lo, rq, pos);
615 default:
616 WARN_ON_ONCE(1);
617 return -EIO;
618 break;
619 }
620}
621
622static inline void loop_update_dio(struct loop_device *lo)
623{
624 __loop_update_dio(lo, io_is_direct(lo->lo_backing_file) |
625 lo->use_dio);
626}
627
628static void loop_reread_partitions(struct loop_device *lo,
629 struct block_device *bdev)
630{
631 int rc;
632
633 /*
634 * bd_mutex has been held already in release path, so don't
635 * acquire it if this function is called in such case.
636 *
637 * If the reread partition isn't from release path, lo_refcnt
638 * must be at least one and it can only become zero when the
639 * current holder is released.
640 */
641 if (!atomic_read(&lo->lo_refcnt))
642 rc = __blkdev_reread_part(bdev);
643 else
644 rc = blkdev_reread_part(bdev);
645 if (rc)
646 pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
647 __func__, lo->lo_number, lo->lo_file_name, rc);
648}
649
650static inline int is_loop_device(struct file *file)
651{
652 struct inode *i = file->f_mapping->host;
653
654 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
655}
656
657static int loop_validate_file(struct file *file, struct block_device *bdev)
658{
659 struct inode *inode = file->f_mapping->host;
660 struct file *f = file;
661
662 /* Avoid recursion */
663 while (is_loop_device(f)) {
664 struct loop_device *l;
665
666 if (f->f_mapping->host->i_bdev == bdev)
667 return -EBADF;
668
669 l = f->f_mapping->host->i_bdev->bd_disk->private_data;
670 if (l->lo_state == Lo_unbound) {
671 return -EINVAL;
672 }
673 f = l->lo_backing_file;
674 }
675 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
676 return -EINVAL;
677 return 0;
678}
679
680/*
681 * loop_change_fd switched the backing store of a loopback device to
682 * a new file. This is useful for operating system installers to free up
683 * the original file and in High Availability environments to switch to
684 * an alternative location for the content in case of server meltdown.
685 * This can only work if the loop device is used read-only, and if the
686 * new backing store is the same size and type as the old backing store.
687 */
688static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
689 unsigned int arg)
690{
691 struct file *file, *old_file;
692 int error;
693
694 error = -ENXIO;
695 if (lo->lo_state != Lo_bound)
696 goto out;
697
698 /* the loop device has to be read-only */
699 error = -EINVAL;
700 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
701 goto out;
702
703 error = -EBADF;
704 file = fget(arg);
705 if (!file)
706 goto out;
707
708 error = loop_validate_file(file, bdev);
709 if (error)
710 goto out_putf;
711
712 old_file = lo->lo_backing_file;
713
714 error = -EINVAL;
715
716 /* size of the new backing store needs to be the same */
717 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
718 goto out_putf;
719
720 /* and ... switch */
721 blk_mq_freeze_queue(lo->lo_queue);
722 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
723 lo->lo_backing_file = file;
724 lo->old_gfp_mask = mapping_gfp_mask(file->f_mapping);
725 mapping_set_gfp_mask(file->f_mapping,
726 lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
727 loop_update_dio(lo);
728 blk_mq_unfreeze_queue(lo->lo_queue);
729
730 fput(old_file);
731 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
732 loop_reread_partitions(lo, bdev);
733 return 0;
734
735 out_putf:
736 fput(file);
737 out:
738 return error;
739}
740
741/* loop sysfs attributes */
742
743static ssize_t loop_attr_show(struct device *dev, char *page,
744 ssize_t (*callback)(struct loop_device *, char *))
745{
746 struct gendisk *disk = dev_to_disk(dev);
747 struct loop_device *lo = disk->private_data;
748
749 return callback(lo, page);
750}
751
752#define LOOP_ATTR_RO(_name) \
753static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
754static ssize_t loop_attr_do_show_##_name(struct device *d, \
755 struct device_attribute *attr, char *b) \
756{ \
757 return loop_attr_show(d, b, loop_attr_##_name##_show); \
758} \
759static struct device_attribute loop_attr_##_name = \
760 __ATTR(_name, 0444, loop_attr_do_show_##_name, NULL);
761
762static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
763{
764 ssize_t ret;
765 char *p = NULL;
766
767 spin_lock_irq(&lo->lo_lock);
768 if (lo->lo_backing_file)
769 p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1);
770 spin_unlock_irq(&lo->lo_lock);
771
772 if (IS_ERR_OR_NULL(p))
773 ret = PTR_ERR(p);
774 else {
775 ret = strlen(p);
776 memmove(buf, p, ret);
777 buf[ret++] = '\n';
778 buf[ret] = 0;
779 }
780
781 return ret;
782}
783
784static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
785{
786 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
787}
788
789static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
790{
791 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
792}
793
794static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
795{
796 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
797
798 return sprintf(buf, "%s\n", autoclear ? "1" : "0");
799}
800
801static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
802{
803 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
804
805 return sprintf(buf, "%s\n", partscan ? "1" : "0");
806}
807
808static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf)
809{
810 int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO);
811
812 return sprintf(buf, "%s\n", dio ? "1" : "0");
813}
814
815LOOP_ATTR_RO(backing_file);
816LOOP_ATTR_RO(offset);
817LOOP_ATTR_RO(sizelimit);
818LOOP_ATTR_RO(autoclear);
819LOOP_ATTR_RO(partscan);
820LOOP_ATTR_RO(dio);
821
822static struct attribute *loop_attrs[] = {
823 &loop_attr_backing_file.attr,
824 &loop_attr_offset.attr,
825 &loop_attr_sizelimit.attr,
826 &loop_attr_autoclear.attr,
827 &loop_attr_partscan.attr,
828 &loop_attr_dio.attr,
829 NULL,
830};
831
832static struct attribute_group loop_attribute_group = {
833 .name = "loop",
834 .attrs= loop_attrs,
835};
836
837static void loop_sysfs_init(struct loop_device *lo)
838{
839 lo->sysfs_inited = !sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
840 &loop_attribute_group);
841}
842
843static void loop_sysfs_exit(struct loop_device *lo)
844{
845 if (lo->sysfs_inited)
846 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
847 &loop_attribute_group);
848}
849
850static void loop_config_discard(struct loop_device *lo)
851{
852 struct file *file = lo->lo_backing_file;
853 struct inode *inode = file->f_mapping->host;
854 struct request_queue *q = lo->lo_queue;
855
856 /*
857 * We use punch hole to reclaim the free space used by the
858 * image a.k.a. discard. However we do not support discard if
859 * encryption is enabled, because it may give an attacker
860 * useful information.
861 */
862 if ((!file->f_op->fallocate) ||
863 lo->lo_encrypt_key_size) {
864 q->limits.discard_granularity = 0;
865 q->limits.discard_alignment = 0;
866 blk_queue_max_discard_sectors(q, 0);
867 blk_queue_max_write_zeroes_sectors(q, 0);
868 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q);
869 return;
870 }
871
872 q->limits.discard_granularity = inode->i_sb->s_blocksize;
873 q->limits.discard_alignment = 0;
874
875 blk_queue_max_discard_sectors(q, UINT_MAX >> 9);
876 blk_queue_max_write_zeroes_sectors(q, UINT_MAX >> 9);
877 blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
878}
879
880static void loop_unprepare_queue(struct loop_device *lo)
881{
882 kthread_flush_worker(&lo->worker);
883 kthread_stop(lo->worker_task);
884}
885
886static int loop_kthread_worker_fn(void *worker_ptr)
887{
888 current->flags |= PF_LESS_THROTTLE;
889 return kthread_worker_fn(worker_ptr);
890}
891
892static int loop_prepare_queue(struct loop_device *lo)
893{
894 kthread_init_worker(&lo->worker);
895 lo->worker_task = kthread_run(loop_kthread_worker_fn,
896 &lo->worker, "loop%d", lo->lo_number);
897 if (IS_ERR(lo->worker_task))
898 return -ENOMEM;
899 set_user_nice(lo->worker_task, MIN_NICE);
900 return 0;
901}
902
903static int loop_set_fd(struct loop_device *lo, fmode_t mode,
904 struct block_device *bdev, unsigned int arg)
905{
906 struct file *file;
907 struct inode *inode;
908 struct address_space *mapping;
909 int lo_flags = 0;
910 int error;
911 loff_t size;
912
913 /* This is safe, since we have a reference from open(). */
914 __module_get(THIS_MODULE);
915
916 error = -EBADF;
917 file = fget(arg);
918 if (!file)
919 goto out;
920
921 error = -EBUSY;
922 if (lo->lo_state != Lo_unbound)
923 goto out_putf;
924
925 error = loop_validate_file(file, bdev);
926 if (error)
927 goto out_putf;
928
929 mapping = file->f_mapping;
930 inode = mapping->host;
931
932 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
933 !file->f_op->write_iter)
934 lo_flags |= LO_FLAGS_READ_ONLY;
935
936 error = -EFBIG;
937 size = get_loop_size(lo, file);
938 if ((loff_t)(sector_t)size != size)
939 goto out_putf;
940 error = loop_prepare_queue(lo);
941 if (error)
942 goto out_putf;
943
944 error = 0;
945
946 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
947
948 lo->use_dio = false;
949 lo->lo_device = bdev;
950 lo->lo_flags = lo_flags;
951 lo->lo_backing_file = file;
952 lo->transfer = NULL;
953 lo->ioctl = NULL;
954 lo->lo_sizelimit = 0;
955 lo->old_gfp_mask = mapping_gfp_mask(mapping);
956 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
957
958 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
959 blk_queue_write_cache(lo->lo_queue, true, false);
960
961 loop_update_dio(lo);
962 set_capacity(lo->lo_disk, size);
963 bd_set_size(bdev, size << 9);
964 loop_sysfs_init(lo);
965 /* let user-space know about the new size */
966 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
967
968 set_blocksize(bdev, S_ISBLK(inode->i_mode) ?
969 block_size(inode->i_bdev) : PAGE_SIZE);
970
971 lo->lo_state = Lo_bound;
972 if (part_shift)
973 lo->lo_flags |= LO_FLAGS_PARTSCAN;
974 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
975 loop_reread_partitions(lo, bdev);
976
977 /* Grab the block_device to prevent its destruction after we
978 * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev).
979 */
980 bdgrab(bdev);
981 return 0;
982
983 out_putf:
984 fput(file);
985 out:
986 /* This is safe: open() is still holding a reference. */
987 module_put(THIS_MODULE);
988 return error;
989}
990
991static int
992loop_release_xfer(struct loop_device *lo)
993{
994 int err = 0;
995 struct loop_func_table *xfer = lo->lo_encryption;
996
997 if (xfer) {
998 if (xfer->release)
999 err = xfer->release(lo);
1000 lo->transfer = NULL;
1001 lo->lo_encryption = NULL;
1002 module_put(xfer->owner);
1003 }
1004 return err;
1005}
1006
1007static int
1008loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
1009 const struct loop_info64 *i)
1010{
1011 int err = 0;
1012
1013 if (xfer) {
1014 struct module *owner = xfer->owner;
1015
1016 if (!try_module_get(owner))
1017 return -EINVAL;
1018 if (xfer->init)
1019 err = xfer->init(lo, i);
1020 if (err)
1021 module_put(owner);
1022 else
1023 lo->lo_encryption = xfer;
1024 }
1025 return err;
1026}
1027
1028static int loop_clr_fd(struct loop_device *lo)
1029{
1030 struct file *filp = lo->lo_backing_file;
1031 gfp_t gfp = lo->old_gfp_mask;
1032 struct block_device *bdev = lo->lo_device;
1033
1034 if (lo->lo_state != Lo_bound)
1035 return -ENXIO;
1036
1037 /*
1038 * If we've explicitly asked to tear down the loop device,
1039 * and it has an elevated reference count, set it for auto-teardown when
1040 * the last reference goes away. This stops $!~#$@ udev from
1041 * preventing teardown because it decided that it needs to run blkid on
1042 * the loopback device whenever they appear. xfstests is notorious for
1043 * failing tests because blkid via udev races with a losetup
1044 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
1045 * command to fail with EBUSY.
1046 */
1047 if (atomic_read(&lo->lo_refcnt) > 1) {
1048 lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
1049 mutex_unlock(&lo->lo_ctl_mutex);
1050 return 0;
1051 }
1052
1053 if (filp == NULL)
1054 return -EINVAL;
1055
1056 /* freeze request queue during the transition */
1057 blk_mq_freeze_queue(lo->lo_queue);
1058
1059 spin_lock_irq(&lo->lo_lock);
1060 lo->lo_state = Lo_rundown;
1061 lo->lo_backing_file = NULL;
1062 spin_unlock_irq(&lo->lo_lock);
1063
1064 loop_release_xfer(lo);
1065 lo->transfer = NULL;
1066 lo->ioctl = NULL;
1067 lo->lo_device = NULL;
1068 lo->lo_encryption = NULL;
1069 lo->lo_offset = 0;
1070 lo->lo_sizelimit = 0;
1071 lo->lo_encrypt_key_size = 0;
1072 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
1073 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
1074 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1075 blk_queue_logical_block_size(lo->lo_queue, 512);
1076 blk_queue_physical_block_size(lo->lo_queue, 512);
1077 blk_queue_io_min(lo->lo_queue, 512);
1078 if (bdev) {
1079 bdput(bdev);
1080 invalidate_bdev(bdev);
1081 bdev->bd_inode->i_mapping->wb_err = 0;
1082 }
1083 set_capacity(lo->lo_disk, 0);
1084 loop_sysfs_exit(lo);
1085 if (bdev) {
1086 bd_set_size(bdev, 0);
1087 /* let user-space know about this change */
1088 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1089 }
1090 mapping_set_gfp_mask(filp->f_mapping, gfp);
1091 lo->lo_state = Lo_unbound;
1092 /* This is safe: open() is still holding a reference. */
1093 module_put(THIS_MODULE);
1094 blk_mq_unfreeze_queue(lo->lo_queue);
1095
1096 if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
1097 loop_reread_partitions(lo, bdev);
1098 lo->lo_flags = 0;
1099 if (!part_shift)
1100 lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
1101 loop_unprepare_queue(lo);
1102 mutex_unlock(&lo->lo_ctl_mutex);
1103 /*
1104 * Need not hold lo_ctl_mutex to fput backing file.
1105 * Calling fput holding lo_ctl_mutex triggers a circular
1106 * lock dependency possibility warning as fput can take
1107 * bd_mutex which is usually taken before lo_ctl_mutex.
1108 */
1109 fput(filp);
1110 return 0;
1111}
1112
1113static int
1114loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1115{
1116 int err;
1117 struct loop_func_table *xfer;
1118 kuid_t uid = current_uid();
1119
1120 if (lo->lo_encrypt_key_size &&
1121 !uid_eq(lo->lo_key_owner, uid) &&
1122 !capable(CAP_SYS_ADMIN))
1123 return -EPERM;
1124 if (lo->lo_state != Lo_bound)
1125 return -ENXIO;
1126 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
1127 return -EINVAL;
1128
1129 /* I/O need to be drained during transfer transition */
1130 blk_mq_freeze_queue(lo->lo_queue);
1131
1132 err = loop_release_xfer(lo);
1133 if (err)
1134 goto exit;
1135
1136 if (info->lo_encrypt_type) {
1137 unsigned int type = info->lo_encrypt_type;
1138
1139 if (type >= MAX_LO_CRYPT) {
1140 err = -EINVAL;
1141 goto exit;
1142 }
1143 xfer = xfer_funcs[type];
1144 if (xfer == NULL) {
1145 err = -EINVAL;
1146 goto exit;
1147 }
1148 } else
1149 xfer = NULL;
1150
1151 err = loop_init_xfer(lo, xfer, info);
1152 if (err)
1153 goto exit;
1154
1155 if (lo->lo_offset != info->lo_offset ||
1156 lo->lo_sizelimit != info->lo_sizelimit) {
1157 if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit)) {
1158 err = -EFBIG;
1159 goto exit;
1160 }
1161 }
1162
1163 loop_config_discard(lo);
1164
1165 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
1166 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
1167 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
1168 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
1169
1170 if (!xfer)
1171 xfer = &none_funcs;
1172 lo->transfer = xfer->transfer;
1173 lo->ioctl = xfer->ioctl;
1174
1175 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
1176 (info->lo_flags & LO_FLAGS_AUTOCLEAR))
1177 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
1178
1179 lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
1180 lo->lo_init[0] = info->lo_init[0];
1181 lo->lo_init[1] = info->lo_init[1];
1182 if (info->lo_encrypt_key_size) {
1183 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
1184 info->lo_encrypt_key_size);
1185 lo->lo_key_owner = uid;
1186 }
1187
1188 /* update dio if lo_offset or transfer is changed */
1189 __loop_update_dio(lo, lo->use_dio);
1190
1191 exit:
1192 blk_mq_unfreeze_queue(lo->lo_queue);
1193
1194 if (!err && (info->lo_flags & LO_FLAGS_PARTSCAN) &&
1195 !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
1196 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1197 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
1198 loop_reread_partitions(lo, lo->lo_device);
1199 }
1200
1201 return err;
1202}
1203
1204static int
1205loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1206{
1207 struct file *file;
1208 struct kstat stat;
1209 int ret;
1210
1211 if (lo->lo_state != Lo_bound) {
1212 mutex_unlock(&lo->lo_ctl_mutex);
1213 return -ENXIO;
1214 }
1215
1216 memset(info, 0, sizeof(*info));
1217 info->lo_number = lo->lo_number;
1218 info->lo_offset = lo->lo_offset;
1219 info->lo_sizelimit = lo->lo_sizelimit;
1220 info->lo_flags = lo->lo_flags;
1221 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1222 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1223 info->lo_encrypt_type =
1224 lo->lo_encryption ? lo->lo_encryption->number : 0;
1225 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1226 info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1227 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1228 lo->lo_encrypt_key_size);
1229 }
1230
1231 /* Drop lo_ctl_mutex while we call into the filesystem. */
1232 file = get_file(lo->lo_backing_file);
1233 mutex_unlock(&lo->lo_ctl_mutex);
1234 ret = vfs_getattr(&file->f_path, &stat, STATX_INO,
1235 AT_STATX_SYNC_AS_STAT);
1236 if (!ret) {
1237 info->lo_device = huge_encode_dev(stat.dev);
1238 info->lo_inode = stat.ino;
1239 info->lo_rdevice = huge_encode_dev(stat.rdev);
1240 }
1241 fput(file);
1242 return ret;
1243}
1244
1245static void
1246loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1247{
1248 memset(info64, 0, sizeof(*info64));
1249 info64->lo_number = info->lo_number;
1250 info64->lo_device = info->lo_device;
1251 info64->lo_inode = info->lo_inode;
1252 info64->lo_rdevice = info->lo_rdevice;
1253 info64->lo_offset = info->lo_offset;
1254 info64->lo_sizelimit = 0;
1255 info64->lo_encrypt_type = info->lo_encrypt_type;
1256 info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1257 info64->lo_flags = info->lo_flags;
1258 info64->lo_init[0] = info->lo_init[0];
1259 info64->lo_init[1] = info->lo_init[1];
1260 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1261 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1262 else
1263 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1264 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1265}
1266
1267static int
1268loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1269{
1270 memset(info, 0, sizeof(*info));
1271 info->lo_number = info64->lo_number;
1272 info->lo_device = info64->lo_device;
1273 info->lo_inode = info64->lo_inode;
1274 info->lo_rdevice = info64->lo_rdevice;
1275 info->lo_offset = info64->lo_offset;
1276 info->lo_encrypt_type = info64->lo_encrypt_type;
1277 info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1278 info->lo_flags = info64->lo_flags;
1279 info->lo_init[0] = info64->lo_init[0];
1280 info->lo_init[1] = info64->lo_init[1];
1281 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1282 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1283 else
1284 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1285 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1286
1287 /* error in case values were truncated */
1288 if (info->lo_device != info64->lo_device ||
1289 info->lo_rdevice != info64->lo_rdevice ||
1290 info->lo_inode != info64->lo_inode ||
1291 info->lo_offset != info64->lo_offset)
1292 return -EOVERFLOW;
1293
1294 return 0;
1295}
1296
1297static int
1298loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1299{
1300 struct loop_info info;
1301 struct loop_info64 info64;
1302
1303 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1304 return -EFAULT;
1305 loop_info64_from_old(&info, &info64);
1306 return loop_set_status(lo, &info64);
1307}
1308
1309static int
1310loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1311{
1312 struct loop_info64 info64;
1313
1314 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1315 return -EFAULT;
1316 return loop_set_status(lo, &info64);
1317}
1318
1319static int
1320loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1321 struct loop_info info;
1322 struct loop_info64 info64;
1323 int err;
1324
1325 if (!arg) {
1326 mutex_unlock(&lo->lo_ctl_mutex);
1327 return -EINVAL;
1328 }
1329 err = loop_get_status(lo, &info64);
1330 if (!err)
1331 err = loop_info64_to_old(&info64, &info);
1332 if (!err && copy_to_user(arg, &info, sizeof(info)))
1333 err = -EFAULT;
1334
1335 return err;
1336}
1337
1338static int
1339loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1340 struct loop_info64 info64;
1341 int err;
1342
1343 if (!arg) {
1344 mutex_unlock(&lo->lo_ctl_mutex);
1345 return -EINVAL;
1346 }
1347 err = loop_get_status(lo, &info64);
1348 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1349 err = -EFAULT;
1350
1351 return err;
1352}
1353
1354static int loop_set_capacity(struct loop_device *lo)
1355{
1356 if (unlikely(lo->lo_state != Lo_bound))
1357 return -ENXIO;
1358
1359 return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
1360}
1361
1362static int loop_set_dio(struct loop_device *lo, unsigned long arg)
1363{
1364 int error = -ENXIO;
1365 if (lo->lo_state != Lo_bound)
1366 goto out;
1367
1368 __loop_update_dio(lo, !!arg);
1369 if (lo->use_dio == !!arg)
1370 return 0;
1371 error = -EINVAL;
1372 out:
1373 return error;
1374}
1375
1376static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
1377{
1378 if (lo->lo_state != Lo_bound)
1379 return -ENXIO;
1380
1381 if (arg < 512 || arg > PAGE_SIZE || !is_power_of_2(arg))
1382 return -EINVAL;
1383
1384 blk_mq_freeze_queue(lo->lo_queue);
1385
1386 blk_queue_logical_block_size(lo->lo_queue, arg);
1387 blk_queue_physical_block_size(lo->lo_queue, arg);
1388 blk_queue_io_min(lo->lo_queue, arg);
1389 loop_update_dio(lo);
1390
1391 blk_mq_unfreeze_queue(lo->lo_queue);
1392
1393 return 0;
1394}
1395
1396static int lo_ioctl(struct block_device *bdev, fmode_t mode,
1397 unsigned int cmd, unsigned long arg)
1398{
1399 struct loop_device *lo = bdev->bd_disk->private_data;
1400 int err;
1401
1402 err = mutex_lock_killable_nested(&lo->lo_ctl_mutex, 1);
1403 if (err)
1404 goto out_unlocked;
1405
1406 switch (cmd) {
1407 case LOOP_SET_FD:
1408 err = loop_set_fd(lo, mode, bdev, arg);
1409 break;
1410 case LOOP_CHANGE_FD:
1411 err = loop_change_fd(lo, bdev, arg);
1412 break;
1413 case LOOP_CLR_FD:
1414 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1415 err = loop_clr_fd(lo);
1416 if (!err)
1417 goto out_unlocked;
1418 break;
1419 case LOOP_SET_STATUS:
1420 err = -EPERM;
1421 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1422 err = loop_set_status_old(lo,
1423 (struct loop_info __user *)arg);
1424 break;
1425 case LOOP_GET_STATUS:
1426 err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1427 /* loop_get_status() unlocks lo_ctl_mutex */
1428 goto out_unlocked;
1429 case LOOP_SET_STATUS64:
1430 err = -EPERM;
1431 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1432 err = loop_set_status64(lo,
1433 (struct loop_info64 __user *) arg);
1434 break;
1435 case LOOP_GET_STATUS64:
1436 err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1437 /* loop_get_status() unlocks lo_ctl_mutex */
1438 goto out_unlocked;
1439 case LOOP_SET_CAPACITY:
1440 err = -EPERM;
1441 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1442 err = loop_set_capacity(lo);
1443 break;
1444 case LOOP_SET_DIRECT_IO:
1445 err = -EPERM;
1446 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1447 err = loop_set_dio(lo, arg);
1448 break;
1449 case LOOP_SET_BLOCK_SIZE:
1450 err = -EPERM;
1451 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1452 err = loop_set_block_size(lo, arg);
1453 break;
1454 default:
1455 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1456 }
1457 mutex_unlock(&lo->lo_ctl_mutex);
1458
1459out_unlocked:
1460 return err;
1461}
1462
1463#ifdef CONFIG_COMPAT
1464struct compat_loop_info {
1465 compat_int_t lo_number; /* ioctl r/o */
1466 compat_dev_t lo_device; /* ioctl r/o */
1467 compat_ulong_t lo_inode; /* ioctl r/o */
1468 compat_dev_t lo_rdevice; /* ioctl r/o */
1469 compat_int_t lo_offset;
1470 compat_int_t lo_encrypt_type;
1471 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1472 compat_int_t lo_flags; /* ioctl r/o */
1473 char lo_name[LO_NAME_SIZE];
1474 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1475 compat_ulong_t lo_init[2];
1476 char reserved[4];
1477};
1478
1479/*
1480 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1481 * - noinlined to reduce stack space usage in main part of driver
1482 */
1483static noinline int
1484loop_info64_from_compat(const struct compat_loop_info __user *arg,
1485 struct loop_info64 *info64)
1486{
1487 struct compat_loop_info info;
1488
1489 if (copy_from_user(&info, arg, sizeof(info)))
1490 return -EFAULT;
1491
1492 memset(info64, 0, sizeof(*info64));
1493 info64->lo_number = info.lo_number;
1494 info64->lo_device = info.lo_device;
1495 info64->lo_inode = info.lo_inode;
1496 info64->lo_rdevice = info.lo_rdevice;
1497 info64->lo_offset = info.lo_offset;
1498 info64->lo_sizelimit = 0;
1499 info64->lo_encrypt_type = info.lo_encrypt_type;
1500 info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1501 info64->lo_flags = info.lo_flags;
1502 info64->lo_init[0] = info.lo_init[0];
1503 info64->lo_init[1] = info.lo_init[1];
1504 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1505 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1506 else
1507 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1508 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1509 return 0;
1510}
1511
1512/*
1513 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1514 * - noinlined to reduce stack space usage in main part of driver
1515 */
1516static noinline int
1517loop_info64_to_compat(const struct loop_info64 *info64,
1518 struct compat_loop_info __user *arg)
1519{
1520 struct compat_loop_info info;
1521
1522 memset(&info, 0, sizeof(info));
1523 info.lo_number = info64->lo_number;
1524 info.lo_device = info64->lo_device;
1525 info.lo_inode = info64->lo_inode;
1526 info.lo_rdevice = info64->lo_rdevice;
1527 info.lo_offset = info64->lo_offset;
1528 info.lo_encrypt_type = info64->lo_encrypt_type;
1529 info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
1530 info.lo_flags = info64->lo_flags;
1531 info.lo_init[0] = info64->lo_init[0];
1532 info.lo_init[1] = info64->lo_init[1];
1533 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1534 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1535 else
1536 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1537 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1538
1539 /* error in case values were truncated */
1540 if (info.lo_device != info64->lo_device ||
1541 info.lo_rdevice != info64->lo_rdevice ||
1542 info.lo_inode != info64->lo_inode ||
1543 info.lo_offset != info64->lo_offset ||
1544 info.lo_init[0] != info64->lo_init[0] ||
1545 info.lo_init[1] != info64->lo_init[1])
1546 return -EOVERFLOW;
1547
1548 if (copy_to_user(arg, &info, sizeof(info)))
1549 return -EFAULT;
1550 return 0;
1551}
1552
1553static int
1554loop_set_status_compat(struct loop_device *lo,
1555 const struct compat_loop_info __user *arg)
1556{
1557 struct loop_info64 info64;
1558 int ret;
1559
1560 ret = loop_info64_from_compat(arg, &info64);
1561 if (ret < 0)
1562 return ret;
1563 return loop_set_status(lo, &info64);
1564}
1565
1566static int
1567loop_get_status_compat(struct loop_device *lo,
1568 struct compat_loop_info __user *arg)
1569{
1570 struct loop_info64 info64;
1571 int err;
1572
1573 if (!arg) {
1574 mutex_unlock(&lo->lo_ctl_mutex);
1575 return -EINVAL;
1576 }
1577 err = loop_get_status(lo, &info64);
1578 if (!err)
1579 err = loop_info64_to_compat(&info64, arg);
1580 return err;
1581}
1582
1583static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1584 unsigned int cmd, unsigned long arg)
1585{
1586 struct loop_device *lo = bdev->bd_disk->private_data;
1587 int err;
1588
1589 switch(cmd) {
1590 case LOOP_SET_STATUS:
1591 err = mutex_lock_killable(&lo->lo_ctl_mutex);
1592 if (!err) {
1593 err = loop_set_status_compat(lo,
1594 (const struct compat_loop_info __user *)arg);
1595 mutex_unlock(&lo->lo_ctl_mutex);
1596 }
1597 break;
1598 case LOOP_GET_STATUS:
1599 err = mutex_lock_killable(&lo->lo_ctl_mutex);
1600 if (!err) {
1601 err = loop_get_status_compat(lo,
1602 (struct compat_loop_info __user *)arg);
1603 /* loop_get_status() unlocks lo_ctl_mutex */
1604 }
1605 break;
1606 case LOOP_SET_CAPACITY:
1607 case LOOP_CLR_FD:
1608 case LOOP_GET_STATUS64:
1609 case LOOP_SET_STATUS64:
1610 arg = (unsigned long) compat_ptr(arg);
1611 /* fall through */
1612 case LOOP_SET_FD:
1613 case LOOP_CHANGE_FD:
1614 case LOOP_SET_BLOCK_SIZE:
1615 err = lo_ioctl(bdev, mode, cmd, arg);
1616 break;
1617 default:
1618 err = -ENOIOCTLCMD;
1619 break;
1620 }
1621 return err;
1622}
1623#endif
1624
1625static int lo_open(struct block_device *bdev, fmode_t mode)
1626{
1627 struct loop_device *lo;
1628 int err = 0;
1629
1630 mutex_lock(&loop_index_mutex);
1631 lo = bdev->bd_disk->private_data;
1632 if (!lo) {
1633 err = -ENXIO;
1634 goto out;
1635 }
1636
1637 atomic_inc(&lo->lo_refcnt);
1638out:
1639 mutex_unlock(&loop_index_mutex);
1640 return err;
1641}
1642
1643static void __lo_release(struct loop_device *lo)
1644{
1645 int err;
1646
1647 if (atomic_dec_return(&lo->lo_refcnt))
1648 return;
1649
1650 mutex_lock(&lo->lo_ctl_mutex);
1651 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
1652 /*
1653 * In autoclear mode, stop the loop thread
1654 * and remove configuration after last close.
1655 */
1656 err = loop_clr_fd(lo);
1657 if (!err)
1658 return;
1659 } else if (lo->lo_state == Lo_bound) {
1660 /*
1661 * Otherwise keep thread (if running) and config,
1662 * but flush possible ongoing bios in thread.
1663 */
1664 blk_mq_freeze_queue(lo->lo_queue);
1665 blk_mq_unfreeze_queue(lo->lo_queue);
1666 }
1667
1668 mutex_unlock(&lo->lo_ctl_mutex);
1669}
1670
1671static void lo_release(struct gendisk *disk, fmode_t mode)
1672{
1673 mutex_lock(&loop_index_mutex);
1674 __lo_release(disk->private_data);
1675 mutex_unlock(&loop_index_mutex);
1676}
1677
1678static const struct block_device_operations lo_fops = {
1679 .owner = THIS_MODULE,
1680 .open = lo_open,
1681 .release = lo_release,
1682 .ioctl = lo_ioctl,
1683#ifdef CONFIG_COMPAT
1684 .compat_ioctl = lo_compat_ioctl,
1685#endif
1686};
1687
1688/*
1689 * And now the modules code and kernel interface.
1690 */
1691static int max_loop;
1692module_param(max_loop, int, 0444);
1693MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1694module_param(max_part, int, 0444);
1695MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1696MODULE_LICENSE("GPL");
1697MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1698
1699int loop_register_transfer(struct loop_func_table *funcs)
1700{
1701 unsigned int n = funcs->number;
1702
1703 if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1704 return -EINVAL;
1705 xfer_funcs[n] = funcs;
1706 return 0;
1707}
1708
1709static int unregister_transfer_cb(int id, void *ptr, void *data)
1710{
1711 struct loop_device *lo = ptr;
1712 struct loop_func_table *xfer = data;
1713
1714 mutex_lock(&lo->lo_ctl_mutex);
1715 if (lo->lo_encryption == xfer)
1716 loop_release_xfer(lo);
1717 mutex_unlock(&lo->lo_ctl_mutex);
1718 return 0;
1719}
1720
1721int loop_unregister_transfer(int number)
1722{
1723 unsigned int n = number;
1724 struct loop_func_table *xfer;
1725
1726 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1727 return -EINVAL;
1728
1729 xfer_funcs[n] = NULL;
1730 idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
1731 return 0;
1732}
1733
1734EXPORT_SYMBOL(loop_register_transfer);
1735EXPORT_SYMBOL(loop_unregister_transfer);
1736
1737static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
1738 const struct blk_mq_queue_data *bd)
1739{
1740 struct request *rq = bd->rq;
1741 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
1742 struct loop_device *lo = rq->q->queuedata;
1743
1744 blk_mq_start_request(rq);
1745
1746 if (lo->lo_state != Lo_bound)
1747 return BLK_STS_IOERR;
1748
1749 switch (req_op(rq)) {
1750 case REQ_OP_FLUSH:
1751 case REQ_OP_DISCARD:
1752 case REQ_OP_WRITE_ZEROES:
1753 cmd->use_aio = false;
1754 break;
1755 default:
1756 cmd->use_aio = lo->use_dio;
1757 break;
1758 }
1759
1760 /* always use the first bio's css */
1761#ifdef CONFIG_BLK_CGROUP
1762 if (cmd->use_aio && rq->bio && rq->bio->bi_css) {
1763 cmd->css = rq->bio->bi_css;
1764 css_get(cmd->css);
1765 } else
1766#endif
1767 cmd->css = NULL;
1768 kthread_queue_work(&lo->worker, &cmd->work);
1769
1770 return BLK_STS_OK;
1771}
1772
1773static void loop_handle_cmd(struct loop_cmd *cmd)
1774{
1775 struct request *rq = blk_mq_rq_from_pdu(cmd);
1776 const bool write = op_is_write(req_op(rq));
1777 struct loop_device *lo = rq->q->queuedata;
1778 int ret = 0;
1779
1780 if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) {
1781 ret = -EIO;
1782 goto failed;
1783 }
1784
1785 ret = do_req_filebacked(lo, rq);
1786 failed:
1787 /* complete non-aio request */
1788 if (!cmd->use_aio || ret) {
1789 cmd->ret = ret ? -EIO : 0;
1790 blk_mq_complete_request(rq);
1791 }
1792}
1793
1794static void loop_queue_work(struct kthread_work *work)
1795{
1796 struct loop_cmd *cmd =
1797 container_of(work, struct loop_cmd, work);
1798
1799 loop_handle_cmd(cmd);
1800}
1801
1802static int loop_init_request(struct blk_mq_tag_set *set, struct request *rq,
1803 unsigned int hctx_idx, unsigned int numa_node)
1804{
1805 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
1806
1807 kthread_init_work(&cmd->work, loop_queue_work);
1808 return 0;
1809}
1810
1811static const struct blk_mq_ops loop_mq_ops = {
1812 .queue_rq = loop_queue_rq,
1813 .init_request = loop_init_request,
1814 .complete = lo_complete_rq,
1815};
1816
1817static int loop_add(struct loop_device **l, int i)
1818{
1819 struct loop_device *lo;
1820 struct gendisk *disk;
1821 int err;
1822
1823 err = -ENOMEM;
1824 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1825 if (!lo)
1826 goto out;
1827
1828 lo->lo_state = Lo_unbound;
1829
1830 /* allocate id, if @id >= 0, we're requesting that specific id */
1831 if (i >= 0) {
1832 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
1833 if (err == -ENOSPC)
1834 err = -EEXIST;
1835 } else {
1836 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
1837 }
1838 if (err < 0)
1839 goto out_free_dev;
1840 i = err;
1841
1842 err = -ENOMEM;
1843 lo->tag_set.ops = &loop_mq_ops;
1844 lo->tag_set.nr_hw_queues = 1;
1845 lo->tag_set.queue_depth = 128;
1846 lo->tag_set.numa_node = NUMA_NO_NODE;
1847 lo->tag_set.cmd_size = sizeof(struct loop_cmd);
1848 lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
1849 lo->tag_set.driver_data = lo;
1850
1851 err = blk_mq_alloc_tag_set(&lo->tag_set);
1852 if (err)
1853 goto out_free_idr;
1854
1855 lo->lo_queue = blk_mq_init_queue(&lo->tag_set);
1856 if (IS_ERR_OR_NULL(lo->lo_queue)) {
1857 err = PTR_ERR(lo->lo_queue);
1858 goto out_cleanup_tags;
1859 }
1860 lo->lo_queue->queuedata = lo;
1861
1862 blk_queue_max_hw_sectors(lo->lo_queue, BLK_DEF_MAX_SECTORS);
1863
1864 /*
1865 * By default, we do buffer IO, so it doesn't make sense to enable
1866 * merge because the I/O submitted to backing file is handled page by
1867 * page. For directio mode, merge does help to dispatch bigger request
1868 * to underlayer disk. We will enable merge once directio is enabled.
1869 */
1870 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
1871
1872 err = -ENOMEM;
1873 disk = lo->lo_disk = alloc_disk(1 << part_shift);
1874 if (!disk)
1875 goto out_free_queue;
1876
1877 /*
1878 * Disable partition scanning by default. The in-kernel partition
1879 * scanning can be requested individually per-device during its
1880 * setup. Userspace can always add and remove partitions from all
1881 * devices. The needed partition minors are allocated from the
1882 * extended minor space, the main loop device numbers will continue
1883 * to match the loop minors, regardless of the number of partitions
1884 * used.
1885 *
1886 * If max_part is given, partition scanning is globally enabled for
1887 * all loop devices. The minors for the main loop devices will be
1888 * multiples of max_part.
1889 *
1890 * Note: Global-for-all-devices, set-only-at-init, read-only module
1891 * parameteters like 'max_loop' and 'max_part' make things needlessly
1892 * complicated, are too static, inflexible and may surprise
1893 * userspace tools. Parameters like this in general should be avoided.
1894 */
1895 if (!part_shift)
1896 disk->flags |= GENHD_FL_NO_PART_SCAN;
1897 disk->flags |= GENHD_FL_EXT_DEVT;
1898 mutex_init(&lo->lo_ctl_mutex);
1899 atomic_set(&lo->lo_refcnt, 0);
1900 lo->lo_number = i;
1901 spin_lock_init(&lo->lo_lock);
1902 disk->major = LOOP_MAJOR;
1903 disk->first_minor = i << part_shift;
1904 disk->fops = &lo_fops;
1905 disk->private_data = lo;
1906 disk->queue = lo->lo_queue;
1907 sprintf(disk->disk_name, "loop%d", i);
1908 add_disk(disk);
1909 *l = lo;
1910 return lo->lo_number;
1911
1912out_free_queue:
1913 blk_cleanup_queue(lo->lo_queue);
1914out_cleanup_tags:
1915 blk_mq_free_tag_set(&lo->tag_set);
1916out_free_idr:
1917 idr_remove(&loop_index_idr, i);
1918out_free_dev:
1919 kfree(lo);
1920out:
1921 return err;
1922}
1923
1924static void loop_remove(struct loop_device *lo)
1925{
1926 del_gendisk(lo->lo_disk);
1927 blk_cleanup_queue(lo->lo_queue);
1928 blk_mq_free_tag_set(&lo->tag_set);
1929 put_disk(lo->lo_disk);
1930 kfree(lo);
1931}
1932
1933static int find_free_cb(int id, void *ptr, void *data)
1934{
1935 struct loop_device *lo = ptr;
1936 struct loop_device **l = data;
1937
1938 if (lo->lo_state == Lo_unbound) {
1939 *l = lo;
1940 return 1;
1941 }
1942 return 0;
1943}
1944
1945static int loop_lookup(struct loop_device **l, int i)
1946{
1947 struct loop_device *lo;
1948 int ret = -ENODEV;
1949
1950 if (i < 0) {
1951 int err;
1952
1953 err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
1954 if (err == 1) {
1955 *l = lo;
1956 ret = lo->lo_number;
1957 }
1958 goto out;
1959 }
1960
1961 /* lookup and return a specific i */
1962 lo = idr_find(&loop_index_idr, i);
1963 if (lo) {
1964 *l = lo;
1965 ret = lo->lo_number;
1966 }
1967out:
1968 return ret;
1969}
1970
1971static struct kobject *loop_probe(dev_t dev, int *part, void *data)
1972{
1973 struct loop_device *lo;
1974 struct kobject *kobj;
1975 int err;
1976
1977 mutex_lock(&loop_index_mutex);
1978 err = loop_lookup(&lo, MINOR(dev) >> part_shift);
1979 if (err < 0)
1980 err = loop_add(&lo, MINOR(dev) >> part_shift);
1981 if (err < 0)
1982 kobj = NULL;
1983 else
1984 kobj = get_disk_and_module(lo->lo_disk);
1985 mutex_unlock(&loop_index_mutex);
1986
1987 *part = 0;
1988 return kobj;
1989}
1990
1991static long loop_control_ioctl(struct file *file, unsigned int cmd,
1992 unsigned long parm)
1993{
1994 struct loop_device *lo;
1995 int ret = -ENOSYS;
1996
1997 mutex_lock(&loop_index_mutex);
1998 switch (cmd) {
1999 case LOOP_CTL_ADD:
2000 ret = loop_lookup(&lo, parm);
2001 if (ret >= 0) {
2002 ret = -EEXIST;
2003 break;
2004 }
2005 ret = loop_add(&lo, parm);
2006 break;
2007 case LOOP_CTL_REMOVE:
2008 ret = loop_lookup(&lo, parm);
2009 if (ret < 0)
2010 break;
2011 ret = mutex_lock_killable(&lo->lo_ctl_mutex);
2012 if (ret)
2013 break;
2014 if (lo->lo_state != Lo_unbound) {
2015 ret = -EBUSY;
2016 mutex_unlock(&lo->lo_ctl_mutex);
2017 break;
2018 }
2019 if (atomic_read(&lo->lo_refcnt) > 0) {
2020 ret = -EBUSY;
2021 mutex_unlock(&lo->lo_ctl_mutex);
2022 break;
2023 }
2024 lo->lo_disk->private_data = NULL;
2025 mutex_unlock(&lo->lo_ctl_mutex);
2026 idr_remove(&loop_index_idr, lo->lo_number);
2027 loop_remove(lo);
2028 break;
2029 case LOOP_CTL_GET_FREE:
2030 ret = loop_lookup(&lo, -1);
2031 if (ret >= 0)
2032 break;
2033 ret = loop_add(&lo, -1);
2034 }
2035 mutex_unlock(&loop_index_mutex);
2036
2037 return ret;
2038}
2039
2040static const struct file_operations loop_ctl_fops = {
2041 .open = nonseekable_open,
2042 .unlocked_ioctl = loop_control_ioctl,
2043 .compat_ioctl = loop_control_ioctl,
2044 .owner = THIS_MODULE,
2045 .llseek = noop_llseek,
2046};
2047
2048static struct miscdevice loop_misc = {
2049 .minor = LOOP_CTRL_MINOR,
2050 .name = "loop-control",
2051 .fops = &loop_ctl_fops,
2052};
2053
2054MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
2055MODULE_ALIAS("devname:loop-control");
2056
2057static int __init loop_init(void)
2058{
2059 int i, nr;
2060 unsigned long range;
2061 struct loop_device *lo;
2062 int err;
2063
2064 part_shift = 0;
2065 if (max_part > 0) {
2066 part_shift = fls(max_part);
2067
2068 /*
2069 * Adjust max_part according to part_shift as it is exported
2070 * to user space so that user can decide correct minor number
2071 * if [s]he want to create more devices.
2072 *
2073 * Note that -1 is required because partition 0 is reserved
2074 * for the whole disk.
2075 */
2076 max_part = (1UL << part_shift) - 1;
2077 }
2078
2079 if ((1UL << part_shift) > DISK_MAX_PARTS) {
2080 err = -EINVAL;
2081 goto err_out;
2082 }
2083
2084 if (max_loop > 1UL << (MINORBITS - part_shift)) {
2085 err = -EINVAL;
2086 goto err_out;
2087 }
2088
2089 /*
2090 * If max_loop is specified, create that many devices upfront.
2091 * This also becomes a hard limit. If max_loop is not specified,
2092 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
2093 * init time. Loop devices can be requested on-demand with the
2094 * /dev/loop-control interface, or be instantiated by accessing
2095 * a 'dead' device node.
2096 */
2097 if (max_loop) {
2098 nr = max_loop;
2099 range = max_loop << part_shift;
2100 } else {
2101 nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
2102 range = 1UL << MINORBITS;
2103 }
2104
2105 err = misc_register(&loop_misc);
2106 if (err < 0)
2107 goto err_out;
2108
2109
2110 if (register_blkdev(LOOP_MAJOR, "loop")) {
2111 err = -EIO;
2112 goto misc_out;
2113 }
2114
2115 blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
2116 THIS_MODULE, loop_probe, NULL, NULL);
2117
2118 /* pre-create number of devices given by config or max_loop */
2119 mutex_lock(&loop_index_mutex);
2120 for (i = 0; i < nr; i++)
2121 loop_add(&lo, i);
2122 mutex_unlock(&loop_index_mutex);
2123
2124 printk(KERN_INFO "loop: module loaded\n");
2125 return 0;
2126
2127misc_out:
2128 misc_deregister(&loop_misc);
2129err_out:
2130 return err;
2131}
2132
2133static int loop_exit_cb(int id, void *ptr, void *data)
2134{
2135 struct loop_device *lo = ptr;
2136
2137 loop_remove(lo);
2138 return 0;
2139}
2140
2141static void __exit loop_exit(void)
2142{
2143 unsigned long range;
2144
2145 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
2146
2147 idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
2148 idr_destroy(&loop_index_idr);
2149
2150 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
2151 unregister_blkdev(LOOP_MAJOR, "loop");
2152
2153 misc_deregister(&loop_misc);
2154}
2155
2156module_init(loop_init);
2157module_exit(loop_exit);
2158
2159#ifndef MODULE
2160static int __init max_loop_setup(char *str)
2161{
2162 max_loop = simple_strtol(str, NULL, 0);
2163 return 1;
2164}
2165
2166__setup("max_loop=", max_loop_setup);
2167#endif