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dt-bindings: mtd: ingenic: Use standard ecc-engine property
[linux/fpc-iii.git] / drivers / block / loop.c
blob1e6edd568214f40400a5fc7eff474b316a4afda0
1 /*
2 * linux/drivers/block/loop.c
3 *
4 * Written by Theodore Ts'o, 3/29/93
5 *
6 * Copyright 1993 by Theodore Ts'o. Redistribution of this file is
7 * permitted under the GNU General Public License.
8 *
9 * DES encryption plus some minor changes by Werner Almesberger, 30-MAY-1993
10 * more DES encryption plus IDEA encryption by Nicholas J. Leon, June 20, 1996
11 *
12 * Modularized and updated for 1.1.16 kernel - Mitch Dsouza 28th May 1994
13 * Adapted for 1.3.59 kernel - Andries Brouwer, 1 Feb 1996
14 *
15 * Fixed do_loop_request() re-entrancy - Vincent.Renardias@waw.com Mar 20, 1997
16 *
17 * Added devfs support - Richard Gooch <rgooch@atnf.csiro.au> 16-Jan-1998
18 *
19 * Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998
20 *
21 * Loadable modules and other fixes by AK, 1998
22 *
23 * Make real block number available to downstream transfer functions, enables
24 * CBC (and relatives) mode encryption requiring unique IVs per data block.
25 * Reed H. Petty, rhp@draper.net
26 *
27 * Maximum number of loop devices now dynamic via max_loop module parameter.
28 * Russell Kroll <rkroll@exploits.org> 19990701
29 *
30 * Maximum number of loop devices when compiled-in now selectable by passing
31 * max_loop=<1-255> to the kernel on boot.
32 * Erik I. Bolsø, <eriki@himolde.no>, Oct 31, 1999
33 *
34 * Completely rewrite request handling to be make_request_fn style and
35 * non blocking, pushing work to a helper thread. Lots of fixes from
36 * Al Viro too.
37 * Jens Axboe <axboe@suse.de>, Nov 2000
38 *
39 * Support up to 256 loop devices
40 * Heinz Mauelshagen <mge@sistina.com>, Feb 2002
41 *
42 * Support for falling back on the write file operation when the address space
43 * operations write_begin is not available on the backing filesystem.
44 * Anton Altaparmakov, 16 Feb 2005
45 *
46 * Still To Fix:
47 * - Advisory locking is ignored here.
48 * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
49 *
50 */
51
52 #include <linux/module.h>
53 #include <linux/moduleparam.h>
54 #include <linux/sched.h>
55 #include <linux/fs.h>
56 #include <linux/file.h>
57 #include <linux/stat.h>
58 #include <linux/errno.h>
59 #include <linux/major.h>
60 #include <linux/wait.h>
61 #include <linux/blkdev.h>
62 #include <linux/blkpg.h>
63 #include <linux/init.h>
64 #include <linux/swap.h>
65 #include <linux/slab.h>
66 #include <linux/compat.h>
67 #include <linux/suspend.h>
68 #include <linux/freezer.h>
69 #include <linux/mutex.h>
70 #include <linux/writeback.h>
71 #include <linux/completion.h>
72 #include <linux/highmem.h>
73 #include <linux/kthread.h>
74 #include <linux/splice.h>
75 #include <linux/sysfs.h>
76 #include <linux/miscdevice.h>
77 #include <linux/falloc.h>
78 #include <linux/uio.h>
79 #include <linux/ioprio.h>
80 #include <linux/blk-cgroup.h>
81
82 #include "loop.h"
83
84 #include <linux/uaccess.h>
85
86 static DEFINE_IDR(loop_index_idr);
87 static DEFINE_MUTEX(loop_ctl_mutex);
88
89 static int max_part;
90 static int part_shift;
91
92 static int transfer_xor(struct loop_device *lo, int cmd,
93 struct page *raw_page, unsigned raw_off,
94 struct page *loop_page, unsigned loop_off,
95 int size, sector_t real_block)
96 {
97 char *raw_buf = kmap_atomic(raw_page) + raw_off;
98 char *loop_buf = kmap_atomic(loop_page) + loop_off;
99 char *in, *out, *key;
100 int i, keysize;
101
102 if (cmd == READ) {
103 in = raw_buf;
104 out = loop_buf;
105 } else {
106 in = loop_buf;
107 out = raw_buf;
108 }
109
110 key = lo->lo_encrypt_key;
111 keysize = lo->lo_encrypt_key_size;
112 for (i = 0; i < size; i++)
113 *out++ = *in++ ^ key[(i & 511) % keysize];
114
115 kunmap_atomic(loop_buf);
116 kunmap_atomic(raw_buf);
117 cond_resched();
118 return 0;
119 }
120
121 static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
122 {
123 if (unlikely(info->lo_encrypt_key_size <= 0))
124 return -EINVAL;
125 return 0;
126 }
127
128 static struct loop_func_table none_funcs = {
129 .number = LO_CRYPT_NONE,
130 };
131
132 static struct loop_func_table xor_funcs = {
133 .number = LO_CRYPT_XOR,
134 .transfer = transfer_xor,
135 .init = xor_init
136 };
137
138 /* xfer_funcs[0] is special - its release function is never called */
139 static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
140 &none_funcs,
141 &xor_funcs
142 };
143
144 static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
145 {
146 loff_t loopsize;
147
148 /* Compute loopsize in bytes */
149 loopsize = i_size_read(file->f_mapping->host);
150 if (offset > 0)
151 loopsize -= offset;
152 /* offset is beyond i_size, weird but possible */
153 if (loopsize < 0)
154 return 0;
155
156 if (sizelimit > 0 && sizelimit < loopsize)
157 loopsize = sizelimit;
158 /*
159 * Unfortunately, if we want to do I/O on the device,
160 * the number of 512-byte sectors has to fit into a sector_t.
161 */
162 return loopsize >> 9;
163 }
164
165 static loff_t get_loop_size(struct loop_device *lo, struct file *file)
166 {
167 return get_size(lo->lo_offset, lo->lo_sizelimit, file);
168 }
169
170 static void __loop_update_dio(struct loop_device *lo, bool dio)
171 {
172 struct file *file = lo->lo_backing_file;
173 struct address_space *mapping = file->f_mapping;
174 struct inode *inode = mapping->host;
175 unsigned short sb_bsize = 0;
176 unsigned dio_align = 0;
177 bool use_dio;
178
179 if (inode->i_sb->s_bdev) {
180 sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
181 dio_align = sb_bsize - 1;
182 }
183
184 /*
185 * We support direct I/O only if lo_offset is aligned with the
186 * logical I/O size of backing device, and the logical block
187 * size of loop is bigger than the backing device's and the loop
188 * needn't transform transfer.
189 *
190 * TODO: the above condition may be loosed in the future, and
191 * direct I/O may be switched runtime at that time because most
192 * of requests in sane applications should be PAGE_SIZE aligned
193 */
194 if (dio) {
195 if (queue_logical_block_size(lo->lo_queue) >= sb_bsize &&
196 !(lo->lo_offset & dio_align) &&
197 mapping->a_ops->direct_IO &&
198 !lo->transfer)
199 use_dio = true;
200 else
201 use_dio = false;
202 } else {
203 use_dio = false;
204 }
205
206 if (lo->use_dio == use_dio)
207 return;
208
209 /* flush dirty pages before changing direct IO */
210 vfs_fsync(file, 0);
211
212 /*
213 * The flag of LO_FLAGS_DIRECT_IO is handled similarly with
214 * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup
215 * will get updated by ioctl(LOOP_GET_STATUS)
216 */
217 blk_mq_freeze_queue(lo->lo_queue);
218 lo->use_dio = use_dio;
219 if (use_dio) {
220 blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, lo->lo_queue);
221 lo->lo_flags |= LO_FLAGS_DIRECT_IO;
222 } else {
223 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
224 lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
225 }
226 blk_mq_unfreeze_queue(lo->lo_queue);
227 }
228
229 static int
230 figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
231 {
232 loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
233 sector_t x = (sector_t)size;
234 struct block_device *bdev = lo->lo_device;
235
236 if (unlikely((loff_t)x != size))
237 return -EFBIG;
238 if (lo->lo_offset != offset)
239 lo->lo_offset = offset;
240 if (lo->lo_sizelimit != sizelimit)
241 lo->lo_sizelimit = sizelimit;
242 set_capacity(lo->lo_disk, x);
243 bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
244 /* let user-space know about the new size */
245 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
246 return 0;
247 }
248
249 static inline int
250 lo_do_transfer(struct loop_device *lo, int cmd,
251 struct page *rpage, unsigned roffs,
252 struct page *lpage, unsigned loffs,
253 int size, sector_t rblock)
254 {
255 int ret;
256
257 ret = lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
258 if (likely(!ret))
259 return 0;
260
261 printk_ratelimited(KERN_ERR
262 "loop: Transfer error at byte offset %llu, length %i.\n",
263 (unsigned long long)rblock << 9, size);
264 return ret;
265 }
266
267 static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)
268 {
269 struct iov_iter i;
270 ssize_t bw;
271
272 iov_iter_bvec(&i, WRITE, bvec, 1, bvec->bv_len);
273
274 file_start_write(file);
275 bw = vfs_iter_write(file, &i, ppos, 0);
276 file_end_write(file);
277
278 if (likely(bw == bvec->bv_len))
279 return 0;
280
281 printk_ratelimited(KERN_ERR
282 "loop: Write error at byte offset %llu, length %i.\n",
283 (unsigned long long)*ppos, bvec->bv_len);
284 if (bw >= 0)
285 bw = -EIO;
286 return bw;
287 }
288
289 static int lo_write_simple(struct loop_device *lo, struct request *rq,
290 loff_t pos)
291 {
292 struct bio_vec bvec;
293 struct req_iterator iter;
294 int ret = 0;
295
296 rq_for_each_segment(bvec, rq, iter) {
297 ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
298 if (ret < 0)
299 break;
300 cond_resched();
301 }
302
303 return ret;
304 }
305
306 /*
307 * This is the slow, transforming version that needs to double buffer the
308 * data as it cannot do the transformations in place without having direct
309 * access to the destination pages of the backing file.
310 */
311 static int lo_write_transfer(struct loop_device *lo, struct request *rq,
312 loff_t pos)
313 {
314 struct bio_vec bvec, b;
315 struct req_iterator iter;
316 struct page *page;
317 int ret = 0;
318
319 page = alloc_page(GFP_NOIO);
320 if (unlikely(!page))
321 return -ENOMEM;
322
323 rq_for_each_segment(bvec, rq, iter) {
324 ret = lo_do_transfer(lo, WRITE, page, 0, bvec.bv_page,
325 bvec.bv_offset, bvec.bv_len, pos >> 9);
326 if (unlikely(ret))
327 break;
328
329 b.bv_page = page;
330 b.bv_offset = 0;
331 b.bv_len = bvec.bv_len;
332 ret = lo_write_bvec(lo->lo_backing_file, &b, &pos);
333 if (ret < 0)
334 break;
335 }
336
337 __free_page(page);
338 return ret;
339 }
340
341 static int lo_read_simple(struct loop_device *lo, struct request *rq,
342 loff_t pos)
343 {
344 struct bio_vec bvec;
345 struct req_iterator iter;
346 struct iov_iter i;
347 ssize_t len;
348
349 rq_for_each_segment(bvec, rq, iter) {
350 iov_iter_bvec(&i, READ, &bvec, 1, bvec.bv_len);
351 len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);
352 if (len < 0)
353 return len;
354
355 flush_dcache_page(bvec.bv_page);
356
357 if (len != bvec.bv_len) {
358 struct bio *bio;
359
360 __rq_for_each_bio(bio, rq)
361 zero_fill_bio(bio);
362 break;
363 }
364 cond_resched();
365 }
366
367 return 0;
368 }
369
370 static int lo_read_transfer(struct loop_device *lo, struct request *rq,
371 loff_t pos)
372 {
373 struct bio_vec bvec, b;
374 struct req_iterator iter;
375 struct iov_iter i;
376 struct page *page;
377 ssize_t len;
378 int ret = 0;
379
380 page = alloc_page(GFP_NOIO);
381 if (unlikely(!page))
382 return -ENOMEM;
383
384 rq_for_each_segment(bvec, rq, iter) {
385 loff_t offset = pos;
386
387 b.bv_page = page;
388 b.bv_offset = 0;
389 b.bv_len = bvec.bv_len;
390
391 iov_iter_bvec(&i, READ, &b, 1, b.bv_len);
392 len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);
393 if (len < 0) {
394 ret = len;
395 goto out_free_page;
396 }
397
398 ret = lo_do_transfer(lo, READ, page, 0, bvec.bv_page,
399 bvec.bv_offset, len, offset >> 9);
400 if (ret)
401 goto out_free_page;
402
403 flush_dcache_page(bvec.bv_page);
404
405 if (len != bvec.bv_len) {
406 struct bio *bio;
407
408 __rq_for_each_bio(bio, rq)
409 zero_fill_bio(bio);
410 break;
411 }
412 }
413
414 ret = 0;
415 out_free_page:
416 __free_page(page);
417 return ret;
418 }
419
420 static int lo_discard(struct loop_device *lo, struct request *rq, loff_t pos)
421 {
422 /*
423 * We use punch hole to reclaim the free space used by the
424 * image a.k.a. discard. However we do not support discard if
425 * encryption is enabled, because it may give an attacker
426 * useful information.
427 */
428 struct file *file = lo->lo_backing_file;
429 int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
430 int ret;
431
432 if ((!file->f_op->fallocate) || lo->lo_encrypt_key_size) {
433 ret = -EOPNOTSUPP;
434 goto out;
435 }
436
437 ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
438 if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
439 ret = -EIO;
440 out:
441 return ret;
442 }
443
444 static int lo_req_flush(struct loop_device *lo, struct request *rq)
445 {
446 struct file *file = lo->lo_backing_file;
447 int ret = vfs_fsync(file, 0);
448 if (unlikely(ret && ret != -EINVAL))
449 ret = -EIO;
450
451 return ret;
452 }
453
454 static void lo_complete_rq(struct request *rq)
455 {
456 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
457 blk_status_t ret = BLK_STS_OK;
458
459 if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) ||
460 req_op(rq) != REQ_OP_READ) {
461 if (cmd->ret < 0)
462 ret = BLK_STS_IOERR;
463 goto end_io;
464 }
465
466 /*
467 * Short READ - if we got some data, advance our request and
468 * retry it. If we got no data, end the rest with EIO.
469 */
470 if (cmd->ret) {
471 blk_update_request(rq, BLK_STS_OK, cmd->ret);
472 cmd->ret = 0;
473 blk_mq_requeue_request(rq, true);
474 } else {
475 if (cmd->use_aio) {
476 struct bio *bio = rq->bio;
477
478 while (bio) {
479 zero_fill_bio(bio);
480 bio = bio->bi_next;
481 }
482 }
483 ret = BLK_STS_IOERR;
484 end_io:
485 blk_mq_end_request(rq, ret);
486 }
487 }
488
489 static void lo_rw_aio_do_completion(struct loop_cmd *cmd)
490 {
491 struct request *rq = blk_mq_rq_from_pdu(cmd);
492
493 if (!atomic_dec_and_test(&cmd->ref))
494 return;
495 kfree(cmd->bvec);
496 cmd->bvec = NULL;
497 blk_mq_complete_request(rq);
498 }
499
500 static void lo_rw_aio_complete(struct kiocb *iocb, long ret, long ret2)
501 {
502 struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb);
503
504 if (cmd->css)
505 css_put(cmd->css);
506 cmd->ret = ret;
507 lo_rw_aio_do_completion(cmd);
508 }
509
510 static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
511 loff_t pos, bool rw)
512 {
513 struct iov_iter iter;
514 struct req_iterator rq_iter;
515 struct bio_vec *bvec;
516 struct request *rq = blk_mq_rq_from_pdu(cmd);
517 struct bio *bio = rq->bio;
518 struct file *file = lo->lo_backing_file;
519 struct bio_vec tmp;
520 unsigned int offset;
521 int nr_bvec = 0;
522 int ret;
523
524 rq_for_each_bvec(tmp, rq, rq_iter)
525 nr_bvec++;
526
527 if (rq->bio != rq->biotail) {
528
529 bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec),
530 GFP_NOIO);
531 if (!bvec)
532 return -EIO;
533 cmd->bvec = bvec;
534
535 /*
536 * The bios of the request may be started from the middle of
537 * the 'bvec' because of bio splitting, so we can't directly
538 * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec
539 * API will take care of all details for us.
540 */
541 rq_for_each_bvec(tmp, rq, rq_iter) {
542 *bvec = tmp;
543 bvec++;
544 }
545 bvec = cmd->bvec;
546 offset = 0;
547 } else {
548 /*
549 * Same here, this bio may be started from the middle of the
550 * 'bvec' because of bio splitting, so offset from the bvec
551 * must be passed to iov iterator
552 */
553 offset = bio->bi_iter.bi_bvec_done;
554 bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
555 }
556 atomic_set(&cmd->ref, 2);
557
558 iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq));
559 iter.iov_offset = offset;
560
561 cmd->iocb.ki_pos = pos;
562 cmd->iocb.ki_filp = file;
563 cmd->iocb.ki_complete = lo_rw_aio_complete;
564 cmd->iocb.ki_flags = IOCB_DIRECT;
565 cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
566 if (cmd->css)
567 kthread_associate_blkcg(cmd->css);
568
569 if (rw == WRITE)
570 ret = call_write_iter(file, &cmd->iocb, &iter);
571 else
572 ret = call_read_iter(file, &cmd->iocb, &iter);
573
574 lo_rw_aio_do_completion(cmd);
575 kthread_associate_blkcg(NULL);
576
577 if (ret != -EIOCBQUEUED)
578 cmd->iocb.ki_complete(&cmd->iocb, ret, 0);
579 return 0;
580 }
581
582 static int do_req_filebacked(struct loop_device *lo, struct request *rq)
583 {
584 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
585 loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
586
587 /*
588 * lo_write_simple and lo_read_simple should have been covered
589 * by io submit style function like lo_rw_aio(), one blocker
590 * is that lo_read_simple() need to call flush_dcache_page after
591 * the page is written from kernel, and it isn't easy to handle
592 * this in io submit style function which submits all segments
593 * of the req at one time. And direct read IO doesn't need to
594 * run flush_dcache_page().
595 */
596 switch (req_op(rq)) {
597 case REQ_OP_FLUSH:
598 return lo_req_flush(lo, rq);
599 case REQ_OP_DISCARD:
600 case REQ_OP_WRITE_ZEROES:
601 return lo_discard(lo, rq, pos);
602 case REQ_OP_WRITE:
603 if (lo->transfer)
604 return lo_write_transfer(lo, rq, pos);
605 else if (cmd->use_aio)
606 return lo_rw_aio(lo, cmd, pos, WRITE);
607 else
608 return lo_write_simple(lo, rq, pos);
609 case REQ_OP_READ:
610 if (lo->transfer)
611 return lo_read_transfer(lo, rq, pos);
612 else if (cmd->use_aio)
613 return lo_rw_aio(lo, cmd, pos, READ);
614 else
615 return lo_read_simple(lo, rq, pos);
616 default:
617 WARN_ON_ONCE(1);
618 return -EIO;
619 }
620 }
621
622 static 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
628 static void loop_reread_partitions(struct loop_device *lo,
629 struct block_device *bdev)
630 {
631 int rc;
632
633 rc = blkdev_reread_part(bdev);
634 if (rc)
635 pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
636 __func__, lo->lo_number, lo->lo_file_name, rc);
637 }
638
639 static inline int is_loop_device(struct file *file)
640 {
641 struct inode *i = file->f_mapping->host;
642
643 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
644 }
645
646 static int loop_validate_file(struct file *file, struct block_device *bdev)
647 {
648 struct inode *inode = file->f_mapping->host;
649 struct file *f = file;
650
651 /* Avoid recursion */
652 while (is_loop_device(f)) {
653 struct loop_device *l;
654
655 if (f->f_mapping->host->i_bdev == bdev)
656 return -EBADF;
657
658 l = f->f_mapping->host->i_bdev->bd_disk->private_data;
659 if (l->lo_state == Lo_unbound) {
660 return -EINVAL;
661 }
662 f = l->lo_backing_file;
663 }
664 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
665 return -EINVAL;
666 return 0;
667 }
668
669 /*
670 * loop_change_fd switched the backing store of a loopback device to
671 * a new file. This is useful for operating system installers to free up
672 * the original file and in High Availability environments to switch to
673 * an alternative location for the content in case of server meltdown.
674 * This can only work if the loop device is used read-only, and if the
675 * new backing store is the same size and type as the old backing store.
676 */
677 static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
678 unsigned int arg)
679 {
680 struct file *file = NULL, *old_file;
681 int error;
682 bool partscan;
683
684 error = mutex_lock_killable(&loop_ctl_mutex);
685 if (error)
686 return error;
687 error = -ENXIO;
688 if (lo->lo_state != Lo_bound)
689 goto out_err;
690
691 /* the loop device has to be read-only */
692 error = -EINVAL;
693 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
694 goto out_err;
695
696 error = -EBADF;
697 file = fget(arg);
698 if (!file)
699 goto out_err;
700
701 error = loop_validate_file(file, bdev);
702 if (error)
703 goto out_err;
704
705 old_file = lo->lo_backing_file;
706
707 error = -EINVAL;
708
709 /* size of the new backing store needs to be the same */
710 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
711 goto out_err;
712
713 /* and ... switch */
714 blk_mq_freeze_queue(lo->lo_queue);
715 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
716 lo->lo_backing_file = file;
717 lo->old_gfp_mask = mapping_gfp_mask(file->f_mapping);
718 mapping_set_gfp_mask(file->f_mapping,
719 lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
720 loop_update_dio(lo);
721 blk_mq_unfreeze_queue(lo->lo_queue);
722 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
723 mutex_unlock(&loop_ctl_mutex);
724 /*
725 * We must drop file reference outside of loop_ctl_mutex as dropping
726 * the file ref can take bd_mutex which creates circular locking
727 * dependency.
728 */
729 fput(old_file);
730 if (partscan)
731 loop_reread_partitions(lo, bdev);
732 return 0;
733
734 out_err:
735 mutex_unlock(&loop_ctl_mutex);
736 if (file)
737 fput(file);
738 return error;
739 }
740
741 /* loop sysfs attributes */
742
743 static 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) \
753 static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
754 static 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 } \
759 static struct device_attribute loop_attr_##_name = \
760 __ATTR(_name, 0444, loop_attr_do_show_##_name, NULL);
761
762 static 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
784 static 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
789 static 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
794 static 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
801 static 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
808 static 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
815 LOOP_ATTR_RO(backing_file);
816 LOOP_ATTR_RO(offset);
817 LOOP_ATTR_RO(sizelimit);
818 LOOP_ATTR_RO(autoclear);
819 LOOP_ATTR_RO(partscan);
820 LOOP_ATTR_RO(dio);
821
822 static 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
832 static struct attribute_group loop_attribute_group = {
833 .name = "loop",
834 .attrs= loop_attrs,
835 };
836
837 static 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
843 static 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
850 static 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
880 static void loop_unprepare_queue(struct loop_device *lo)
881 {
882 kthread_flush_worker(&lo->worker);
883 kthread_stop(lo->worker_task);
884 }
885
886 static int loop_kthread_worker_fn(void *worker_ptr)
887 {
888 current->flags |= PF_LESS_THROTTLE;
889 return kthread_worker_fn(worker_ptr);
890 }
891
892 static 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
903 static 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 bool partscan;
913
914 /* This is safe, since we have a reference from open(). */
915 __module_get(THIS_MODULE);
916
917 error = -EBADF;
918 file = fget(arg);
919 if (!file)
920 goto out;
921
922 error = mutex_lock_killable(&loop_ctl_mutex);
923 if (error)
924 goto out_putf;
925
926 error = -EBUSY;
927 if (lo->lo_state != Lo_unbound)
928 goto out_unlock;
929
930 error = loop_validate_file(file, bdev);
931 if (error)
932 goto out_unlock;
933
934 mapping = file->f_mapping;
935 inode = mapping->host;
936
937 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
938 !file->f_op->write_iter)
939 lo_flags |= LO_FLAGS_READ_ONLY;
940
941 error = -EFBIG;
942 size = get_loop_size(lo, file);
943 if ((loff_t)(sector_t)size != size)
944 goto out_unlock;
945 error = loop_prepare_queue(lo);
946 if (error)
947 goto out_unlock;
948
949 error = 0;
950
951 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
952
953 lo->use_dio = false;
954 lo->lo_device = bdev;
955 lo->lo_flags = lo_flags;
956 lo->lo_backing_file = file;
957 lo->transfer = NULL;
958 lo->ioctl = NULL;
959 lo->lo_sizelimit = 0;
960 lo->old_gfp_mask = mapping_gfp_mask(mapping);
961 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
962
963 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
964 blk_queue_write_cache(lo->lo_queue, true, false);
965
966 loop_update_dio(lo);
967 set_capacity(lo->lo_disk, size);
968 bd_set_size(bdev, size << 9);
969 loop_sysfs_init(lo);
970 /* let user-space know about the new size */
971 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
972
973 set_blocksize(bdev, S_ISBLK(inode->i_mode) ?
974 block_size(inode->i_bdev) : PAGE_SIZE);
975
976 lo->lo_state = Lo_bound;
977 if (part_shift)
978 lo->lo_flags |= LO_FLAGS_PARTSCAN;
979 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
980
981 /* Grab the block_device to prevent its destruction after we
982 * put /dev/loopXX inode. Later in __loop_clr_fd() we bdput(bdev).
983 */
984 bdgrab(bdev);
985 mutex_unlock(&loop_ctl_mutex);
986 if (partscan)
987 loop_reread_partitions(lo, bdev);
988 return 0;
989
990 out_unlock:
991 mutex_unlock(&loop_ctl_mutex);
992 out_putf:
993 fput(file);
994 out:
995 /* This is safe: open() is still holding a reference. */
996 module_put(THIS_MODULE);
997 return error;
998 }
999
1000 static int
1001 loop_release_xfer(struct loop_device *lo)
1002 {
1003 int err = 0;
1004 struct loop_func_table *xfer = lo->lo_encryption;
1005
1006 if (xfer) {
1007 if (xfer->release)
1008 err = xfer->release(lo);
1009 lo->transfer = NULL;
1010 lo->lo_encryption = NULL;
1011 module_put(xfer->owner);
1012 }
1013 return err;
1014 }
1015
1016 static int
1017 loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
1018 const struct loop_info64 *i)
1019 {
1020 int err = 0;
1021
1022 if (xfer) {
1023 struct module *owner = xfer->owner;
1024
1025 if (!try_module_get(owner))
1026 return -EINVAL;
1027 if (xfer->init)
1028 err = xfer->init(lo, i);
1029 if (err)
1030 module_put(owner);
1031 else
1032 lo->lo_encryption = xfer;
1033 }
1034 return err;
1035 }
1036
1037 static int __loop_clr_fd(struct loop_device *lo, bool release)
1038 {
1039 struct file *filp = NULL;
1040 gfp_t gfp = lo->old_gfp_mask;
1041 struct block_device *bdev = lo->lo_device;
1042 int err = 0;
1043 bool partscan = false;
1044 int lo_number;
1045
1046 mutex_lock(&loop_ctl_mutex);
1047 if (WARN_ON_ONCE(lo->lo_state != Lo_rundown)) {
1048 err = -ENXIO;
1049 goto out_unlock;
1050 }
1051
1052 filp = lo->lo_backing_file;
1053 if (filp == NULL) {
1054 err = -EINVAL;
1055 goto out_unlock;
1056 }
1057
1058 /* freeze request queue during the transition */
1059 blk_mq_freeze_queue(lo->lo_queue);
1060
1061 spin_lock_irq(&lo->lo_lock);
1062 lo->lo_backing_file = NULL;
1063 spin_unlock_irq(&lo->lo_lock);
1064
1065 loop_release_xfer(lo);
1066 lo->transfer = NULL;
1067 lo->ioctl = NULL;
1068 lo->lo_device = NULL;
1069 lo->lo_encryption = NULL;
1070 lo->lo_offset = 0;
1071 lo->lo_sizelimit = 0;
1072 lo->lo_encrypt_key_size = 0;
1073 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
1074 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
1075 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1076 blk_queue_logical_block_size(lo->lo_queue, 512);
1077 blk_queue_physical_block_size(lo->lo_queue, 512);
1078 blk_queue_io_min(lo->lo_queue, 512);
1079 if (bdev) {
1080 bdput(bdev);
1081 invalidate_bdev(bdev);
1082 bdev->bd_inode->i_mapping->wb_err = 0;
1083 }
1084 set_capacity(lo->lo_disk, 0);
1085 loop_sysfs_exit(lo);
1086 if (bdev) {
1087 bd_set_size(bdev, 0);
1088 /* let user-space know about this change */
1089 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1090 }
1091 mapping_set_gfp_mask(filp->f_mapping, gfp);
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 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN && bdev;
1097 lo_number = lo->lo_number;
1098 loop_unprepare_queue(lo);
1099 out_unlock:
1100 mutex_unlock(&loop_ctl_mutex);
1101 if (partscan) {
1102 /*
1103 * bd_mutex has been held already in release path, so don't
1104 * acquire it if this function is called in such case.
1105 *
1106 * If the reread partition isn't from release path, lo_refcnt
1107 * must be at least one and it can only become zero when the
1108 * current holder is released.
1109 */
1110 if (release)
1111 err = __blkdev_reread_part(bdev);
1112 else
1113 err = blkdev_reread_part(bdev);
1114 if (err)
1115 pr_warn("%s: partition scan of loop%d failed (rc=%d)\n",
1116 __func__, lo_number, err);
1117 /* Device is gone, no point in returning error */
1118 err = 0;
1119 }
1120
1121 /*
1122 * lo->lo_state is set to Lo_unbound here after above partscan has
1123 * finished.
1124 *
1125 * There cannot be anybody else entering __loop_clr_fd() as
1126 * lo->lo_backing_file is already cleared and Lo_rundown state
1127 * protects us from all the other places trying to change the 'lo'
1128 * device.
1129 */
1130 mutex_lock(&loop_ctl_mutex);
1131 lo->lo_flags = 0;
1132 if (!part_shift)
1133 lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
1134 lo->lo_state = Lo_unbound;
1135 mutex_unlock(&loop_ctl_mutex);
1136
1137 /*
1138 * Need not hold loop_ctl_mutex to fput backing file.
1139 * Calling fput holding loop_ctl_mutex triggers a circular
1140 * lock dependency possibility warning as fput can take
1141 * bd_mutex which is usually taken before loop_ctl_mutex.
1142 */
1143 if (filp)
1144 fput(filp);
1145 return err;
1146 }
1147
1148 static int loop_clr_fd(struct loop_device *lo)
1149 {
1150 int err;
1151
1152 err = mutex_lock_killable(&loop_ctl_mutex);
1153 if (err)
1154 return err;
1155 if (lo->lo_state != Lo_bound) {
1156 mutex_unlock(&loop_ctl_mutex);
1157 return -ENXIO;
1158 }
1159 /*
1160 * If we've explicitly asked to tear down the loop device,
1161 * and it has an elevated reference count, set it for auto-teardown when
1162 * the last reference goes away. This stops $!~#$@ udev from
1163 * preventing teardown because it decided that it needs to run blkid on
1164 * the loopback device whenever they appear. xfstests is notorious for
1165 * failing tests because blkid via udev races with a losetup
1166 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
1167 * command to fail with EBUSY.
1168 */
1169 if (atomic_read(&lo->lo_refcnt) > 1) {
1170 lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
1171 mutex_unlock(&loop_ctl_mutex);
1172 return 0;
1173 }
1174 lo->lo_state = Lo_rundown;
1175 mutex_unlock(&loop_ctl_mutex);
1176
1177 return __loop_clr_fd(lo, false);
1178 }
1179
1180 static int
1181 loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1182 {
1183 int err;
1184 struct loop_func_table *xfer;
1185 kuid_t uid = current_uid();
1186 struct block_device *bdev;
1187 bool partscan = false;
1188
1189 err = mutex_lock_killable(&loop_ctl_mutex);
1190 if (err)
1191 return err;
1192 if (lo->lo_encrypt_key_size &&
1193 !uid_eq(lo->lo_key_owner, uid) &&
1194 !capable(CAP_SYS_ADMIN)) {
1195 err = -EPERM;
1196 goto out_unlock;
1197 }
1198 if (lo->lo_state != Lo_bound) {
1199 err = -ENXIO;
1200 goto out_unlock;
1201 }
1202 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE) {
1203 err = -EINVAL;
1204 goto out_unlock;
1205 }
1206
1207 if (lo->lo_offset != info->lo_offset ||
1208 lo->lo_sizelimit != info->lo_sizelimit) {
1209 sync_blockdev(lo->lo_device);
1210 kill_bdev(lo->lo_device);
1211 }
1212
1213 /* I/O need to be drained during transfer transition */
1214 blk_mq_freeze_queue(lo->lo_queue);
1215
1216 err = loop_release_xfer(lo);
1217 if (err)
1218 goto out_unfreeze;
1219
1220 if (info->lo_encrypt_type) {
1221 unsigned int type = info->lo_encrypt_type;
1222
1223 if (type >= MAX_LO_CRYPT) {
1224 err = -EINVAL;
1225 goto out_unfreeze;
1226 }
1227 xfer = xfer_funcs[type];
1228 if (xfer == NULL) {
1229 err = -EINVAL;
1230 goto out_unfreeze;
1231 }
1232 } else
1233 xfer = NULL;
1234
1235 err = loop_init_xfer(lo, xfer, info);
1236 if (err)
1237 goto out_unfreeze;
1238
1239 if (lo->lo_offset != info->lo_offset ||
1240 lo->lo_sizelimit != info->lo_sizelimit) {
1241 /* kill_bdev should have truncated all the pages */
1242 if (lo->lo_device->bd_inode->i_mapping->nrpages) {
1243 err = -EAGAIN;
1244 pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n",
1245 __func__, lo->lo_number, lo->lo_file_name,
1246 lo->lo_device->bd_inode->i_mapping->nrpages);
1247 goto out_unfreeze;
1248 }
1249 if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit)) {
1250 err = -EFBIG;
1251 goto out_unfreeze;
1252 }
1253 }
1254
1255 loop_config_discard(lo);
1256
1257 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
1258 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
1259 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
1260 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
1261
1262 if (!xfer)
1263 xfer = &none_funcs;
1264 lo->transfer = xfer->transfer;
1265 lo->ioctl = xfer->ioctl;
1266
1267 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
1268 (info->lo_flags & LO_FLAGS_AUTOCLEAR))
1269 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
1270
1271 lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
1272 lo->lo_init[0] = info->lo_init[0];
1273 lo->lo_init[1] = info->lo_init[1];
1274 if (info->lo_encrypt_key_size) {
1275 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
1276 info->lo_encrypt_key_size);
1277 lo->lo_key_owner = uid;
1278 }
1279
1280 /* update dio if lo_offset or transfer is changed */
1281 __loop_update_dio(lo, lo->use_dio);
1282
1283 out_unfreeze:
1284 blk_mq_unfreeze_queue(lo->lo_queue);
1285
1286 if (!err && (info->lo_flags & LO_FLAGS_PARTSCAN) &&
1287 !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
1288 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1289 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
1290 bdev = lo->lo_device;
1291 partscan = true;
1292 }
1293 out_unlock:
1294 mutex_unlock(&loop_ctl_mutex);
1295 if (partscan)
1296 loop_reread_partitions(lo, bdev);
1297
1298 return err;
1299 }
1300
1301 static int
1302 loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1303 {
1304 struct path path;
1305 struct kstat stat;
1306 int ret;
1307
1308 ret = mutex_lock_killable(&loop_ctl_mutex);
1309 if (ret)
1310 return ret;
1311 if (lo->lo_state != Lo_bound) {
1312 mutex_unlock(&loop_ctl_mutex);
1313 return -ENXIO;
1314 }
1315
1316 memset(info, 0, sizeof(*info));
1317 info->lo_number = lo->lo_number;
1318 info->lo_offset = lo->lo_offset;
1319 info->lo_sizelimit = lo->lo_sizelimit;
1320 info->lo_flags = lo->lo_flags;
1321 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1322 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1323 info->lo_encrypt_type =
1324 lo->lo_encryption ? lo->lo_encryption->number : 0;
1325 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1326 info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1327 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1328 lo->lo_encrypt_key_size);
1329 }
1330
1331 /* Drop loop_ctl_mutex while we call into the filesystem. */
1332 path = lo->lo_backing_file->f_path;
1333 path_get(&path);
1334 mutex_unlock(&loop_ctl_mutex);
1335 ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT);
1336 if (!ret) {
1337 info->lo_device = huge_encode_dev(stat.dev);
1338 info->lo_inode = stat.ino;
1339 info->lo_rdevice = huge_encode_dev(stat.rdev);
1340 }
1341 path_put(&path);
1342 return ret;
1343 }
1344
1345 static void
1346 loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1347 {
1348 memset(info64, 0, sizeof(*info64));
1349 info64->lo_number = info->lo_number;
1350 info64->lo_device = info->lo_device;
1351 info64->lo_inode = info->lo_inode;
1352 info64->lo_rdevice = info->lo_rdevice;
1353 info64->lo_offset = info->lo_offset;
1354 info64->lo_sizelimit = 0;
1355 info64->lo_encrypt_type = info->lo_encrypt_type;
1356 info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1357 info64->lo_flags = info->lo_flags;
1358 info64->lo_init[0] = info->lo_init[0];
1359 info64->lo_init[1] = info->lo_init[1];
1360 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1361 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1362 else
1363 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1364 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1365 }
1366
1367 static int
1368 loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1369 {
1370 memset(info, 0, sizeof(*info));
1371 info->lo_number = info64->lo_number;
1372 info->lo_device = info64->lo_device;
1373 info->lo_inode = info64->lo_inode;
1374 info->lo_rdevice = info64->lo_rdevice;
1375 info->lo_offset = info64->lo_offset;
1376 info->lo_encrypt_type = info64->lo_encrypt_type;
1377 info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1378 info->lo_flags = info64->lo_flags;
1379 info->lo_init[0] = info64->lo_init[0];
1380 info->lo_init[1] = info64->lo_init[1];
1381 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1382 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1383 else
1384 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1385 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1386
1387 /* error in case values were truncated */
1388 if (info->lo_device != info64->lo_device ||
1389 info->lo_rdevice != info64->lo_rdevice ||
1390 info->lo_inode != info64->lo_inode ||
1391 info->lo_offset != info64->lo_offset)
1392 return -EOVERFLOW;
1393
1394 return 0;
1395 }
1396
1397 static int
1398 loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1399 {
1400 struct loop_info info;
1401 struct loop_info64 info64;
1402
1403 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1404 return -EFAULT;
1405 loop_info64_from_old(&info, &info64);
1406 return loop_set_status(lo, &info64);
1407 }
1408
1409 static int
1410 loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1411 {
1412 struct loop_info64 info64;
1413
1414 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1415 return -EFAULT;
1416 return loop_set_status(lo, &info64);
1417 }
1418
1419 static int
1420 loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1421 struct loop_info info;
1422 struct loop_info64 info64;
1423 int err;
1424
1425 if (!arg)
1426 return -EINVAL;
1427 err = loop_get_status(lo, &info64);
1428 if (!err)
1429 err = loop_info64_to_old(&info64, &info);
1430 if (!err && copy_to_user(arg, &info, sizeof(info)))
1431 err = -EFAULT;
1432
1433 return err;
1434 }
1435
1436 static int
1437 loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1438 struct loop_info64 info64;
1439 int err;
1440
1441 if (!arg)
1442 return -EINVAL;
1443 err = loop_get_status(lo, &info64);
1444 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1445 err = -EFAULT;
1446
1447 return err;
1448 }
1449
1450 static int loop_set_capacity(struct loop_device *lo)
1451 {
1452 if (unlikely(lo->lo_state != Lo_bound))
1453 return -ENXIO;
1454
1455 return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
1456 }
1457
1458 static int loop_set_dio(struct loop_device *lo, unsigned long arg)
1459 {
1460 int error = -ENXIO;
1461 if (lo->lo_state != Lo_bound)
1462 goto out;
1463
1464 __loop_update_dio(lo, !!arg);
1465 if (lo->use_dio == !!arg)
1466 return 0;
1467 error = -EINVAL;
1468 out:
1469 return error;
1470 }
1471
1472 static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
1473 {
1474 int err = 0;
1475
1476 if (lo->lo_state != Lo_bound)
1477 return -ENXIO;
1478
1479 if (arg < 512 || arg > PAGE_SIZE || !is_power_of_2(arg))
1480 return -EINVAL;
1481
1482 if (lo->lo_queue->limits.logical_block_size != arg) {
1483 sync_blockdev(lo->lo_device);
1484 kill_bdev(lo->lo_device);
1485 }
1486
1487 blk_mq_freeze_queue(lo->lo_queue);
1488
1489 /* kill_bdev should have truncated all the pages */
1490 if (lo->lo_queue->limits.logical_block_size != arg &&
1491 lo->lo_device->bd_inode->i_mapping->nrpages) {
1492 err = -EAGAIN;
1493 pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n",
1494 __func__, lo->lo_number, lo->lo_file_name,
1495 lo->lo_device->bd_inode->i_mapping->nrpages);
1496 goto out_unfreeze;
1497 }
1498
1499 blk_queue_logical_block_size(lo->lo_queue, arg);
1500 blk_queue_physical_block_size(lo->lo_queue, arg);
1501 blk_queue_io_min(lo->lo_queue, arg);
1502 loop_update_dio(lo);
1503 out_unfreeze:
1504 blk_mq_unfreeze_queue(lo->lo_queue);
1505
1506 return err;
1507 }
1508
1509 static int lo_simple_ioctl(struct loop_device *lo, unsigned int cmd,
1510 unsigned long arg)
1511 {
1512 int err;
1513
1514 err = mutex_lock_killable(&loop_ctl_mutex);
1515 if (err)
1516 return err;
1517 switch (cmd) {
1518 case LOOP_SET_CAPACITY:
1519 err = loop_set_capacity(lo);
1520 break;
1521 case LOOP_SET_DIRECT_IO:
1522 err = loop_set_dio(lo, arg);
1523 break;
1524 case LOOP_SET_BLOCK_SIZE:
1525 err = loop_set_block_size(lo, arg);
1526 break;
1527 default:
1528 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1529 }
1530 mutex_unlock(&loop_ctl_mutex);
1531 return err;
1532 }
1533
1534 static int lo_ioctl(struct block_device *bdev, fmode_t mode,
1535 unsigned int cmd, unsigned long arg)
1536 {
1537 struct loop_device *lo = bdev->bd_disk->private_data;
1538 int err;
1539
1540 switch (cmd) {
1541 case LOOP_SET_FD:
1542 return loop_set_fd(lo, mode, bdev, arg);
1543 case LOOP_CHANGE_FD:
1544 return loop_change_fd(lo, bdev, arg);
1545 case LOOP_CLR_FD:
1546 return loop_clr_fd(lo);
1547 case LOOP_SET_STATUS:
1548 err = -EPERM;
1549 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
1550 err = loop_set_status_old(lo,
1551 (struct loop_info __user *)arg);
1552 }
1553 break;
1554 case LOOP_GET_STATUS:
1555 return loop_get_status_old(lo, (struct loop_info __user *) arg);
1556 case LOOP_SET_STATUS64:
1557 err = -EPERM;
1558 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
1559 err = loop_set_status64(lo,
1560 (struct loop_info64 __user *) arg);
1561 }
1562 break;
1563 case LOOP_GET_STATUS64:
1564 return loop_get_status64(lo, (struct loop_info64 __user *) arg);
1565 case LOOP_SET_CAPACITY:
1566 case LOOP_SET_DIRECT_IO:
1567 case LOOP_SET_BLOCK_SIZE:
1568 if (!(mode & FMODE_WRITE) && !capable(CAP_SYS_ADMIN))
1569 return -EPERM;
1570 /* Fall through */
1571 default:
1572 err = lo_simple_ioctl(lo, cmd, arg);
1573 break;
1574 }
1575
1576 return err;
1577 }
1578
1579 #ifdef CONFIG_COMPAT
1580 struct compat_loop_info {
1581 compat_int_t lo_number; /* ioctl r/o */
1582 compat_dev_t lo_device; /* ioctl r/o */
1583 compat_ulong_t lo_inode; /* ioctl r/o */
1584 compat_dev_t lo_rdevice; /* ioctl r/o */
1585 compat_int_t lo_offset;
1586 compat_int_t lo_encrypt_type;
1587 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1588 compat_int_t lo_flags; /* ioctl r/o */
1589 char lo_name[LO_NAME_SIZE];
1590 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1591 compat_ulong_t lo_init[2];
1592 char reserved[4];
1593 };
1594
1595 /*
1596 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1597 * - noinlined to reduce stack space usage in main part of driver
1598 */
1599 static noinline int
1600 loop_info64_from_compat(const struct compat_loop_info __user *arg,
1601 struct loop_info64 *info64)
1602 {
1603 struct compat_loop_info info;
1604
1605 if (copy_from_user(&info, arg, sizeof(info)))
1606 return -EFAULT;
1607
1608 memset(info64, 0, sizeof(*info64));
1609 info64->lo_number = info.lo_number;
1610 info64->lo_device = info.lo_device;
1611 info64->lo_inode = info.lo_inode;
1612 info64->lo_rdevice = info.lo_rdevice;
1613 info64->lo_offset = info.lo_offset;
1614 info64->lo_sizelimit = 0;
1615 info64->lo_encrypt_type = info.lo_encrypt_type;
1616 info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1617 info64->lo_flags = info.lo_flags;
1618 info64->lo_init[0] = info.lo_init[0];
1619 info64->lo_init[1] = info.lo_init[1];
1620 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1621 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1622 else
1623 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1624 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1625 return 0;
1626 }
1627
1628 /*
1629 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1630 * - noinlined to reduce stack space usage in main part of driver
1631 */
1632 static noinline int
1633 loop_info64_to_compat(const struct loop_info64 *info64,
1634 struct compat_loop_info __user *arg)
1635 {
1636 struct compat_loop_info info;
1637
1638 memset(&info, 0, sizeof(info));
1639 info.lo_number = info64->lo_number;
1640 info.lo_device = info64->lo_device;
1641 info.lo_inode = info64->lo_inode;
1642 info.lo_rdevice = info64->lo_rdevice;
1643 info.lo_offset = info64->lo_offset;
1644 info.lo_encrypt_type = info64->lo_encrypt_type;
1645 info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
1646 info.lo_flags = info64->lo_flags;
1647 info.lo_init[0] = info64->lo_init[0];
1648 info.lo_init[1] = info64->lo_init[1];
1649 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1650 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1651 else
1652 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1653 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1654
1655 /* error in case values were truncated */
1656 if (info.lo_device != info64->lo_device ||
1657 info.lo_rdevice != info64->lo_rdevice ||
1658 info.lo_inode != info64->lo_inode ||
1659 info.lo_offset != info64->lo_offset ||
1660 info.lo_init[0] != info64->lo_init[0] ||
1661 info.lo_init[1] != info64->lo_init[1])
1662 return -EOVERFLOW;
1663
1664 if (copy_to_user(arg, &info, sizeof(info)))
1665 return -EFAULT;
1666 return 0;
1667 }
1668
1669 static int
1670 loop_set_status_compat(struct loop_device *lo,
1671 const struct compat_loop_info __user *arg)
1672 {
1673 struct loop_info64 info64;
1674 int ret;
1675
1676 ret = loop_info64_from_compat(arg, &info64);
1677 if (ret < 0)
1678 return ret;
1679 return loop_set_status(lo, &info64);
1680 }
1681
1682 static int
1683 loop_get_status_compat(struct loop_device *lo,
1684 struct compat_loop_info __user *arg)
1685 {
1686 struct loop_info64 info64;
1687 int err;
1688
1689 if (!arg)
1690 return -EINVAL;
1691 err = loop_get_status(lo, &info64);
1692 if (!err)
1693 err = loop_info64_to_compat(&info64, arg);
1694 return err;
1695 }
1696
1697 static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1698 unsigned int cmd, unsigned long arg)
1699 {
1700 struct loop_device *lo = bdev->bd_disk->private_data;
1701 int err;
1702
1703 switch(cmd) {
1704 case LOOP_SET_STATUS:
1705 err = loop_set_status_compat(lo,
1706 (const struct compat_loop_info __user *)arg);
1707 break;
1708 case LOOP_GET_STATUS:
1709 err = loop_get_status_compat(lo,
1710 (struct compat_loop_info __user *)arg);
1711 break;
1712 case LOOP_SET_CAPACITY:
1713 case LOOP_CLR_FD:
1714 case LOOP_GET_STATUS64:
1715 case LOOP_SET_STATUS64:
1716 arg = (unsigned long) compat_ptr(arg);
1717 /* fall through */
1718 case LOOP_SET_FD:
1719 case LOOP_CHANGE_FD:
1720 case LOOP_SET_BLOCK_SIZE:
1721 err = lo_ioctl(bdev, mode, cmd, arg);
1722 break;
1723 default:
1724 err = -ENOIOCTLCMD;
1725 break;
1726 }
1727 return err;
1728 }
1729 #endif
1730
1731 static int lo_open(struct block_device *bdev, fmode_t mode)
1732 {
1733 struct loop_device *lo;
1734 int err;
1735
1736 err = mutex_lock_killable(&loop_ctl_mutex);
1737 if (err)
1738 return err;
1739 lo = bdev->bd_disk->private_data;
1740 if (!lo) {
1741 err = -ENXIO;
1742 goto out;
1743 }
1744
1745 atomic_inc(&lo->lo_refcnt);
1746 out:
1747 mutex_unlock(&loop_ctl_mutex);
1748 return err;
1749 }
1750
1751 static void lo_release(struct gendisk *disk, fmode_t mode)
1752 {
1753 struct loop_device *lo;
1754
1755 mutex_lock(&loop_ctl_mutex);
1756 lo = disk->private_data;
1757 if (atomic_dec_return(&lo->lo_refcnt))
1758 goto out_unlock;
1759
1760 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
1761 if (lo->lo_state != Lo_bound)
1762 goto out_unlock;
1763 lo->lo_state = Lo_rundown;
1764 mutex_unlock(&loop_ctl_mutex);
1765 /*
1766 * In autoclear mode, stop the loop thread
1767 * and remove configuration after last close.
1768 */
1769 __loop_clr_fd(lo, true);
1770 return;
1771 } else if (lo->lo_state == Lo_bound) {
1772 /*
1773 * Otherwise keep thread (if running) and config,
1774 * but flush possible ongoing bios in thread.
1775 */
1776 blk_mq_freeze_queue(lo->lo_queue);
1777 blk_mq_unfreeze_queue(lo->lo_queue);
1778 }
1779
1780 out_unlock:
1781 mutex_unlock(&loop_ctl_mutex);
1782 }
1783
1784 static const struct block_device_operations lo_fops = {
1785 .owner = THIS_MODULE,
1786 .open = lo_open,
1787 .release = lo_release,
1788 .ioctl = lo_ioctl,
1789 #ifdef CONFIG_COMPAT
1790 .compat_ioctl = lo_compat_ioctl,
1791 #endif
1792 };
1793
1794 /*
1795 * And now the modules code and kernel interface.
1796 */
1797 static int max_loop;
1798 module_param(max_loop, int, 0444);
1799 MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1800 module_param(max_part, int, 0444);
1801 MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1802 MODULE_LICENSE("GPL");
1803 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1804
1805 int loop_register_transfer(struct loop_func_table *funcs)
1806 {
1807 unsigned int n = funcs->number;
1808
1809 if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1810 return -EINVAL;
1811 xfer_funcs[n] = funcs;
1812 return 0;
1813 }
1814
1815 static int unregister_transfer_cb(int id, void *ptr, void *data)
1816 {
1817 struct loop_device *lo = ptr;
1818 struct loop_func_table *xfer = data;
1819
1820 mutex_lock(&loop_ctl_mutex);
1821 if (lo->lo_encryption == xfer)
1822 loop_release_xfer(lo);
1823 mutex_unlock(&loop_ctl_mutex);
1824 return 0;
1825 }
1826
1827 int loop_unregister_transfer(int number)
1828 {
1829 unsigned int n = number;
1830 struct loop_func_table *xfer;
1831
1832 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1833 return -EINVAL;
1834
1835 xfer_funcs[n] = NULL;
1836 idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
1837 return 0;
1838 }
1839
1840 EXPORT_SYMBOL(loop_register_transfer);
1841 EXPORT_SYMBOL(loop_unregister_transfer);
1842
1843 static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
1844 const struct blk_mq_queue_data *bd)
1845 {
1846 struct request *rq = bd->rq;
1847 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
1848 struct loop_device *lo = rq->q->queuedata;
1849
1850 blk_mq_start_request(rq);
1851
1852 if (lo->lo_state != Lo_bound)
1853 return BLK_STS_IOERR;
1854
1855 switch (req_op(rq)) {
1856 case REQ_OP_FLUSH:
1857 case REQ_OP_DISCARD:
1858 case REQ_OP_WRITE_ZEROES:
1859 cmd->use_aio = false;
1860 break;
1861 default:
1862 cmd->use_aio = lo->use_dio;
1863 break;
1864 }
1865
1866 /* always use the first bio's css */
1867 #ifdef CONFIG_BLK_CGROUP
1868 if (cmd->use_aio && rq->bio && rq->bio->bi_blkg) {
1869 cmd->css = &bio_blkcg(rq->bio)->css;
1870 css_get(cmd->css);
1871 } else
1872 #endif
1873 cmd->css = NULL;
1874 kthread_queue_work(&lo->worker, &cmd->work);
1875
1876 return BLK_STS_OK;
1877 }
1878
1879 static void loop_handle_cmd(struct loop_cmd *cmd)
1880 {
1881 struct request *rq = blk_mq_rq_from_pdu(cmd);
1882 const bool write = op_is_write(req_op(rq));
1883 struct loop_device *lo = rq->q->queuedata;
1884 int ret = 0;
1885
1886 if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) {
1887 ret = -EIO;
1888 goto failed;
1889 }
1890
1891 ret = do_req_filebacked(lo, rq);
1892 failed:
1893 /* complete non-aio request */
1894 if (!cmd->use_aio || ret) {
1895 cmd->ret = ret ? -EIO : 0;
1896 blk_mq_complete_request(rq);
1897 }
1898 }
1899
1900 static void loop_queue_work(struct kthread_work *work)
1901 {
1902 struct loop_cmd *cmd =
1903 container_of(work, struct loop_cmd, work);
1904
1905 loop_handle_cmd(cmd);
1906 }
1907
1908 static int loop_init_request(struct blk_mq_tag_set *set, struct request *rq,
1909 unsigned int hctx_idx, unsigned int numa_node)
1910 {
1911 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
1912
1913 kthread_init_work(&cmd->work, loop_queue_work);
1914 return 0;
1915 }
1916
1917 static const struct blk_mq_ops loop_mq_ops = {
1918 .queue_rq = loop_queue_rq,
1919 .init_request = loop_init_request,
1920 .complete = lo_complete_rq,
1921 };
1922
1923 static int loop_add(struct loop_device **l, int i)
1924 {
1925 struct loop_device *lo;
1926 struct gendisk *disk;
1927 int err;
1928
1929 err = -ENOMEM;
1930 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1931 if (!lo)
1932 goto out;
1933
1934 lo->lo_state = Lo_unbound;
1935
1936 /* allocate id, if @id >= 0, we're requesting that specific id */
1937 if (i >= 0) {
1938 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
1939 if (err == -ENOSPC)
1940 err = -EEXIST;
1941 } else {
1942 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
1943 }
1944 if (err < 0)
1945 goto out_free_dev;
1946 i = err;
1947
1948 err = -ENOMEM;
1949 lo->tag_set.ops = &loop_mq_ops;
1950 lo->tag_set.nr_hw_queues = 1;
1951 lo->tag_set.queue_depth = 128;
1952 lo->tag_set.numa_node = NUMA_NO_NODE;
1953 lo->tag_set.cmd_size = sizeof(struct loop_cmd);
1954 lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
1955 lo->tag_set.driver_data = lo;
1956
1957 err = blk_mq_alloc_tag_set(&lo->tag_set);
1958 if (err)
1959 goto out_free_idr;
1960
1961 lo->lo_queue = blk_mq_init_queue(&lo->tag_set);
1962 if (IS_ERR(lo->lo_queue)) {
1963 err = PTR_ERR(lo->lo_queue);
1964 goto out_cleanup_tags;
1965 }
1966 lo->lo_queue->queuedata = lo;
1967
1968 blk_queue_max_hw_sectors(lo->lo_queue, BLK_DEF_MAX_SECTORS);
1969
1970 /*
1971 * By default, we do buffer IO, so it doesn't make sense to enable
1972 * merge because the I/O submitted to backing file is handled page by
1973 * page. For directio mode, merge does help to dispatch bigger request
1974 * to underlayer disk. We will enable merge once directio is enabled.
1975 */
1976 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
1977
1978 err = -ENOMEM;
1979 disk = lo->lo_disk = alloc_disk(1 << part_shift);
1980 if (!disk)
1981 goto out_free_queue;
1982
1983 /*
1984 * Disable partition scanning by default. The in-kernel partition
1985 * scanning can be requested individually per-device during its
1986 * setup. Userspace can always add and remove partitions from all
1987 * devices. The needed partition minors are allocated from the
1988 * extended minor space, the main loop device numbers will continue
1989 * to match the loop minors, regardless of the number of partitions
1990 * used.
1991 *
1992 * If max_part is given, partition scanning is globally enabled for
1993 * all loop devices. The minors for the main loop devices will be
1994 * multiples of max_part.
1995 *
1996 * Note: Global-for-all-devices, set-only-at-init, read-only module
1997 * parameteters like 'max_loop' and 'max_part' make things needlessly
1998 * complicated, are too static, inflexible and may surprise
1999 * userspace tools. Parameters like this in general should be avoided.
2000 */
2001 if (!part_shift)
2002 disk->flags |= GENHD_FL_NO_PART_SCAN;
2003 disk->flags |= GENHD_FL_EXT_DEVT;
2004 atomic_set(&lo->lo_refcnt, 0);
2005 lo->lo_number = i;
2006 spin_lock_init(&lo->lo_lock);
2007 disk->major = LOOP_MAJOR;
2008 disk->first_minor = i << part_shift;
2009 disk->fops = &lo_fops;
2010 disk->private_data = lo;
2011 disk->queue = lo->lo_queue;
2012 sprintf(disk->disk_name, "loop%d", i);
2013 add_disk(disk);
2014 *l = lo;
2015 return lo->lo_number;
2016
2017 out_free_queue:
2018 blk_cleanup_queue(lo->lo_queue);
2019 out_cleanup_tags:
2020 blk_mq_free_tag_set(&lo->tag_set);
2021 out_free_idr:
2022 idr_remove(&loop_index_idr, i);
2023 out_free_dev:
2024 kfree(lo);
2025 out:
2026 return err;
2027 }
2028
2029 static void loop_remove(struct loop_device *lo)
2030 {
2031 del_gendisk(lo->lo_disk);
2032 blk_cleanup_queue(lo->lo_queue);
2033 blk_mq_free_tag_set(&lo->tag_set);
2034 put_disk(lo->lo_disk);
2035 kfree(lo);
2036 }
2037
2038 static int find_free_cb(int id, void *ptr, void *data)
2039 {
2040 struct loop_device *lo = ptr;
2041 struct loop_device **l = data;
2042
2043 if (lo->lo_state == Lo_unbound) {
2044 *l = lo;
2045 return 1;
2046 }
2047 return 0;
2048 }
2049
2050 static int loop_lookup(struct loop_device **l, int i)
2051 {
2052 struct loop_device *lo;
2053 int ret = -ENODEV;
2054
2055 if (i < 0) {
2056 int err;
2057
2058 err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
2059 if (err == 1) {
2060 *l = lo;
2061 ret = lo->lo_number;
2062 }
2063 goto out;
2064 }
2065
2066 /* lookup and return a specific i */
2067 lo = idr_find(&loop_index_idr, i);
2068 if (lo) {
2069 *l = lo;
2070 ret = lo->lo_number;
2071 }
2072 out:
2073 return ret;
2074 }
2075
2076 static struct kobject *loop_probe(dev_t dev, int *part, void *data)
2077 {
2078 struct loop_device *lo;
2079 struct kobject *kobj;
2080 int err;
2081
2082 mutex_lock(&loop_ctl_mutex);
2083 err = loop_lookup(&lo, MINOR(dev) >> part_shift);
2084 if (err < 0)
2085 err = loop_add(&lo, MINOR(dev) >> part_shift);
2086 if (err < 0)
2087 kobj = NULL;
2088 else
2089 kobj = get_disk_and_module(lo->lo_disk);
2090 mutex_unlock(&loop_ctl_mutex);
2091
2092 *part = 0;
2093 return kobj;
2094 }
2095
2096 static long loop_control_ioctl(struct file *file, unsigned int cmd,
2097 unsigned long parm)
2098 {
2099 struct loop_device *lo;
2100 int ret;
2101
2102 ret = mutex_lock_killable(&loop_ctl_mutex);
2103 if (ret)
2104 return ret;
2105
2106 ret = -ENOSYS;
2107 switch (cmd) {
2108 case LOOP_CTL_ADD:
2109 ret = loop_lookup(&lo, parm);
2110 if (ret >= 0) {
2111 ret = -EEXIST;
2112 break;
2113 }
2114 ret = loop_add(&lo, parm);
2115 break;
2116 case LOOP_CTL_REMOVE:
2117 ret = loop_lookup(&lo, parm);
2118 if (ret < 0)
2119 break;
2120 if (lo->lo_state != Lo_unbound) {
2121 ret = -EBUSY;
2122 break;
2123 }
2124 if (atomic_read(&lo->lo_refcnt) > 0) {
2125 ret = -EBUSY;
2126 break;
2127 }
2128 lo->lo_disk->private_data = NULL;
2129 idr_remove(&loop_index_idr, lo->lo_number);
2130 loop_remove(lo);
2131 break;
2132 case LOOP_CTL_GET_FREE:
2133 ret = loop_lookup(&lo, -1);
2134 if (ret >= 0)
2135 break;
2136 ret = loop_add(&lo, -1);
2137 }
2138 mutex_unlock(&loop_ctl_mutex);
2139
2140 return ret;
2141 }
2142
2143 static const struct file_operations loop_ctl_fops = {
2144 .open = nonseekable_open,
2145 .unlocked_ioctl = loop_control_ioctl,
2146 .compat_ioctl = loop_control_ioctl,
2147 .owner = THIS_MODULE,
2148 .llseek = noop_llseek,
2149 };
2150
2151 static struct miscdevice loop_misc = {
2152 .minor = LOOP_CTRL_MINOR,
2153 .name = "loop-control",
2154 .fops = &loop_ctl_fops,
2155 };
2156
2157 MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
2158 MODULE_ALIAS("devname:loop-control");
2159
2160 static int __init loop_init(void)
2161 {
2162 int i, nr;
2163 unsigned long range;
2164 struct loop_device *lo;
2165 int err;
2166
2167 part_shift = 0;
2168 if (max_part > 0) {
2169 part_shift = fls(max_part);
2170
2171 /*
2172 * Adjust max_part according to part_shift as it is exported
2173 * to user space so that user can decide correct minor number
2174 * if [s]he want to create more devices.
2175 *
2176 * Note that -1 is required because partition 0 is reserved
2177 * for the whole disk.
2178 */
2179 max_part = (1UL << part_shift) - 1;
2180 }
2181
2182 if ((1UL << part_shift) > DISK_MAX_PARTS) {
2183 err = -EINVAL;
2184 goto err_out;
2185 }
2186
2187 if (max_loop > 1UL << (MINORBITS - part_shift)) {
2188 err = -EINVAL;
2189 goto err_out;
2190 }
2191
2192 /*
2193 * If max_loop is specified, create that many devices upfront.
2194 * This also becomes a hard limit. If max_loop is not specified,
2195 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
2196 * init time. Loop devices can be requested on-demand with the
2197 * /dev/loop-control interface, or be instantiated by accessing
2198 * a 'dead' device node.
2199 */
2200 if (max_loop) {
2201 nr = max_loop;
2202 range = max_loop << part_shift;
2203 } else {
2204 nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
2205 range = 1UL << MINORBITS;
2206 }
2207
2208 err = misc_register(&loop_misc);
2209 if (err < 0)
2210 goto err_out;
2211
2212
2213 if (register_blkdev(LOOP_MAJOR, "loop")) {
2214 err = -EIO;
2215 goto misc_out;
2216 }
2217
2218 blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
2219 THIS_MODULE, loop_probe, NULL, NULL);
2220
2221 /* pre-create number of devices given by config or max_loop */
2222 mutex_lock(&loop_ctl_mutex);
2223 for (i = 0; i < nr; i++)
2224 loop_add(&lo, i);
2225 mutex_unlock(&loop_ctl_mutex);
2226
2227 printk(KERN_INFO "loop: module loaded\n");
2228 return 0;
2229
2230 misc_out:
2231 misc_deregister(&loop_misc);
2232 err_out:
2233 return err;
2234 }
2235
2236 static int loop_exit_cb(int id, void *ptr, void *data)
2237 {
2238 struct loop_device *lo = ptr;
2239
2240 loop_remove(lo);
2241 return 0;
2242 }
2243
2244 static void __exit loop_exit(void)
2245 {
2246 unsigned long range;
2247
2248 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
2249
2250 idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
2251 idr_destroy(&loop_index_idr);
2252
2253 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
2254 unregister_blkdev(LOOP_MAJOR, "loop");
2255
2256 misc_deregister(&loop_misc);
2257 }
2258
2259 module_init(loop_init);
2260 module_exit(loop_exit);
2261
2262 #ifndef MODULE
2263 static int __init max_loop_setup(char *str)
2264 {
2265 max_loop = simple_strtol(str, NULL, 0);
2266 return 1;
2267 }
2268
2269 __setup("max_loop=", max_loop_setup);
2270 #endif
Linux with added FPC-III support