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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright 1993 by Theodore Ts'o.
4 */
5#include <linux/module.h>
6#include <linux/moduleparam.h>
7#include <linux/sched.h>
8#include <linux/fs.h>
9#include <linux/pagemap.h>
10#include <linux/file.h>
11#include <linux/stat.h>
12#include <linux/errno.h>
13#include <linux/major.h>
14#include <linux/wait.h>
15#include <linux/blkpg.h>
16#include <linux/init.h>
17#include <linux/swap.h>
18#include <linux/slab.h>
19#include <linux/compat.h>
20#include <linux/suspend.h>
21#include <linux/freezer.h>
22#include <linux/mutex.h>
23#include <linux/writeback.h>
24#include <linux/completion.h>
25#include <linux/highmem.h>
26#include <linux/splice.h>
27#include <linux/sysfs.h>
28#include <linux/miscdevice.h>
29#include <linux/falloc.h>
30#include <linux/uio.h>
31#include <linux/ioprio.h>
32#include <linux/blk-cgroup.h>
33#include <linux/sched/mm.h>
34#include <linux/statfs.h>
35#include <linux/uaccess.h>
36#include <linux/blk-mq.h>
37#include <linux/spinlock.h>
38#include <uapi/linux/loop.h>
39
40/* Possible states of device */
41enum {
42 Lo_unbound,
43 Lo_bound,
44 Lo_rundown,
45 Lo_deleting,
46};
47
48struct loop_func_table;
49
50struct loop_device {
51 int lo_number;
52 loff_t lo_offset;
53 loff_t lo_sizelimit;
54 int lo_flags;
55 char lo_file_name[LO_NAME_SIZE];
56
57 struct file * lo_backing_file;
58 struct block_device *lo_device;
59
60 gfp_t old_gfp_mask;
61
62 spinlock_t lo_lock;
63 int lo_state;
64 spinlock_t lo_work_lock;
65 struct workqueue_struct *workqueue;
66 struct work_struct rootcg_work;
67 struct list_head rootcg_cmd_list;
68 struct list_head idle_worker_list;
69 struct rb_root worker_tree;
70 struct timer_list timer;
71 bool use_dio;
72 bool sysfs_inited;
73
74 struct request_queue *lo_queue;
75 struct blk_mq_tag_set tag_set;
76 struct gendisk *lo_disk;
77 struct mutex lo_mutex;
78 bool idr_visible;
79};
80
81struct loop_cmd {
82 struct list_head list_entry;
83 bool use_aio; /* use AIO interface to handle I/O */
84 atomic_t ref; /* only for aio */
85 long ret;
86 struct kiocb iocb;
87 struct bio_vec *bvec;
88 struct cgroup_subsys_state *blkcg_css;
89 struct cgroup_subsys_state *memcg_css;
90};
91
92#define LOOP_IDLE_WORKER_TIMEOUT (60 * HZ)
93#define LOOP_DEFAULT_HW_Q_DEPTH 128
94
95static DEFINE_IDR(loop_index_idr);
96static DEFINE_MUTEX(loop_ctl_mutex);
97static DEFINE_MUTEX(loop_validate_mutex);
98
99/**
100 * loop_global_lock_killable() - take locks for safe loop_validate_file() test
101 *
102 * @lo: struct loop_device
103 * @global: true if @lo is about to bind another "struct loop_device", false otherwise
104 *
105 * Returns 0 on success, -EINTR otherwise.
106 *
107 * Since loop_validate_file() traverses on other "struct loop_device" if
108 * is_loop_device() is true, we need a global lock for serializing concurrent
109 * loop_configure()/loop_change_fd()/__loop_clr_fd() calls.
110 */
111static int loop_global_lock_killable(struct loop_device *lo, bool global)
112{
113 int err;
114
115 if (global) {
116 err = mutex_lock_killable(&loop_validate_mutex);
117 if (err)
118 return err;
119 }
120 err = mutex_lock_killable(&lo->lo_mutex);
121 if (err && global)
122 mutex_unlock(&loop_validate_mutex);
123 return err;
124}
125
126/**
127 * loop_global_unlock() - release locks taken by loop_global_lock_killable()
128 *
129 * @lo: struct loop_device
130 * @global: true if @lo was about to bind another "struct loop_device", false otherwise
131 */
132static void loop_global_unlock(struct loop_device *lo, bool global)
133{
134 mutex_unlock(&lo->lo_mutex);
135 if (global)
136 mutex_unlock(&loop_validate_mutex);
137}
138
139static int max_part;
140static int part_shift;
141
142static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
143{
144 loff_t loopsize;
145
146 /* Compute loopsize in bytes */
147 loopsize = i_size_read(file->f_mapping->host);
148 if (offset > 0)
149 loopsize -= offset;
150 /* offset is beyond i_size, weird but possible */
151 if (loopsize < 0)
152 return 0;
153
154 if (sizelimit > 0 && sizelimit < loopsize)
155 loopsize = sizelimit;
156 /*
157 * Unfortunately, if we want to do I/O on the device,
158 * the number of 512-byte sectors has to fit into a sector_t.
159 */
160 return loopsize >> 9;
161}
162
163static loff_t get_loop_size(struct loop_device *lo, struct file *file)
164{
165 return get_size(lo->lo_offset, lo->lo_sizelimit, file);
166}
167
168/*
169 * We support direct I/O only if lo_offset is aligned with the logical I/O size
170 * of backing device, and the logical block size of loop is bigger than that of
171 * the backing device.
172 */
173static bool lo_bdev_can_use_dio(struct loop_device *lo,
174 struct block_device *backing_bdev)
175{
176 unsigned short sb_bsize = bdev_logical_block_size(backing_bdev);
177
178 if (queue_logical_block_size(lo->lo_queue) < sb_bsize)
179 return false;
180 if (lo->lo_offset & (sb_bsize - 1))
181 return false;
182 return true;
183}
184
185static void __loop_update_dio(struct loop_device *lo, bool dio)
186{
187 struct file *file = lo->lo_backing_file;
188 struct inode *inode = file->f_mapping->host;
189 struct block_device *backing_bdev = NULL;
190 bool use_dio;
191
192 if (S_ISBLK(inode->i_mode))
193 backing_bdev = I_BDEV(inode);
194 else if (inode->i_sb->s_bdev)
195 backing_bdev = inode->i_sb->s_bdev;
196
197 use_dio = dio && (file->f_mode & FMODE_CAN_ODIRECT) &&
198 (!backing_bdev || lo_bdev_can_use_dio(lo, backing_bdev));
199
200 if (lo->use_dio == use_dio)
201 return;
202
203 /* flush dirty pages before changing direct IO */
204 vfs_fsync(file, 0);
205
206 /*
207 * The flag of LO_FLAGS_DIRECT_IO is handled similarly with
208 * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup
209 * will get updated by ioctl(LOOP_GET_STATUS)
210 */
211 if (lo->lo_state == Lo_bound)
212 blk_mq_freeze_queue(lo->lo_queue);
213 lo->use_dio = use_dio;
214 if (use_dio) {
215 blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, lo->lo_queue);
216 lo->lo_flags |= LO_FLAGS_DIRECT_IO;
217 } else {
218 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
219 lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
220 }
221 if (lo->lo_state == Lo_bound)
222 blk_mq_unfreeze_queue(lo->lo_queue);
223}
224
225/**
226 * loop_set_size() - sets device size and notifies userspace
227 * @lo: struct loop_device to set the size for
228 * @size: new size of the loop device
229 *
230 * Callers must validate that the size passed into this function fits into
231 * a sector_t, eg using loop_validate_size()
232 */
233static void loop_set_size(struct loop_device *lo, loff_t size)
234{
235 if (!set_capacity_and_notify(lo->lo_disk, size))
236 kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
237}
238
239static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)
240{
241 struct iov_iter i;
242 ssize_t bw;
243
244 iov_iter_bvec(&i, ITER_SOURCE, bvec, 1, bvec->bv_len);
245
246 bw = vfs_iter_write(file, &i, ppos, 0);
247
248 if (likely(bw == bvec->bv_len))
249 return 0;
250
251 printk_ratelimited(KERN_ERR
252 "loop: Write error at byte offset %llu, length %i.\n",
253 (unsigned long long)*ppos, bvec->bv_len);
254 if (bw >= 0)
255 bw = -EIO;
256 return bw;
257}
258
259static int lo_write_simple(struct loop_device *lo, struct request *rq,
260 loff_t pos)
261{
262 struct bio_vec bvec;
263 struct req_iterator iter;
264 int ret = 0;
265
266 rq_for_each_segment(bvec, rq, iter) {
267 ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
268 if (ret < 0)
269 break;
270 cond_resched();
271 }
272
273 return ret;
274}
275
276static int lo_read_simple(struct loop_device *lo, struct request *rq,
277 loff_t pos)
278{
279 struct bio_vec bvec;
280 struct req_iterator iter;
281 struct iov_iter i;
282 ssize_t len;
283
284 rq_for_each_segment(bvec, rq, iter) {
285 iov_iter_bvec(&i, ITER_DEST, &bvec, 1, bvec.bv_len);
286 len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);
287 if (len < 0)
288 return len;
289
290 flush_dcache_page(bvec.bv_page);
291
292 if (len != bvec.bv_len) {
293 struct bio *bio;
294
295 __rq_for_each_bio(bio, rq)
296 zero_fill_bio(bio);
297 break;
298 }
299 cond_resched();
300 }
301
302 return 0;
303}
304
305static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos,
306 int mode)
307{
308 /*
309 * We use fallocate to manipulate the space mappings used by the image
310 * a.k.a. discard/zerorange.
311 */
312 struct file *file = lo->lo_backing_file;
313 int ret;
314
315 mode |= FALLOC_FL_KEEP_SIZE;
316
317 if (!bdev_max_discard_sectors(lo->lo_device))
318 return -EOPNOTSUPP;
319
320 ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
321 if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
322 return -EIO;
323 return ret;
324}
325
326static int lo_req_flush(struct loop_device *lo, struct request *rq)
327{
328 int ret = vfs_fsync(lo->lo_backing_file, 0);
329 if (unlikely(ret && ret != -EINVAL))
330 ret = -EIO;
331
332 return ret;
333}
334
335static void lo_complete_rq(struct request *rq)
336{
337 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
338 blk_status_t ret = BLK_STS_OK;
339
340 if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) ||
341 req_op(rq) != REQ_OP_READ) {
342 if (cmd->ret < 0)
343 ret = errno_to_blk_status(cmd->ret);
344 goto end_io;
345 }
346
347 /*
348 * Short READ - if we got some data, advance our request and
349 * retry it. If we got no data, end the rest with EIO.
350 */
351 if (cmd->ret) {
352 blk_update_request(rq, BLK_STS_OK, cmd->ret);
353 cmd->ret = 0;
354 blk_mq_requeue_request(rq, true);
355 } else {
356 if (cmd->use_aio) {
357 struct bio *bio = rq->bio;
358
359 while (bio) {
360 zero_fill_bio(bio);
361 bio = bio->bi_next;
362 }
363 }
364 ret = BLK_STS_IOERR;
365end_io:
366 blk_mq_end_request(rq, ret);
367 }
368}
369
370static void lo_rw_aio_do_completion(struct loop_cmd *cmd)
371{
372 struct request *rq = blk_mq_rq_from_pdu(cmd);
373
374 if (!atomic_dec_and_test(&cmd->ref))
375 return;
376 kfree(cmd->bvec);
377 cmd->bvec = NULL;
378 if (likely(!blk_should_fake_timeout(rq->q)))
379 blk_mq_complete_request(rq);
380}
381
382static void lo_rw_aio_complete(struct kiocb *iocb, long ret)
383{
384 struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb);
385
386 cmd->ret = ret;
387 lo_rw_aio_do_completion(cmd);
388}
389
390static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
391 loff_t pos, int rw)
392{
393 struct iov_iter iter;
394 struct req_iterator rq_iter;
395 struct bio_vec *bvec;
396 struct request *rq = blk_mq_rq_from_pdu(cmd);
397 struct bio *bio = rq->bio;
398 struct file *file = lo->lo_backing_file;
399 struct bio_vec tmp;
400 unsigned int offset;
401 int nr_bvec = 0;
402 int ret;
403
404 rq_for_each_bvec(tmp, rq, rq_iter)
405 nr_bvec++;
406
407 if (rq->bio != rq->biotail) {
408
409 bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec),
410 GFP_NOIO);
411 if (!bvec)
412 return -EIO;
413 cmd->bvec = bvec;
414
415 /*
416 * The bios of the request may be started from the middle of
417 * the 'bvec' because of bio splitting, so we can't directly
418 * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec
419 * API will take care of all details for us.
420 */
421 rq_for_each_bvec(tmp, rq, rq_iter) {
422 *bvec = tmp;
423 bvec++;
424 }
425 bvec = cmd->bvec;
426 offset = 0;
427 } else {
428 /*
429 * Same here, this bio may be started from the middle of the
430 * 'bvec' because of bio splitting, so offset from the bvec
431 * must be passed to iov iterator
432 */
433 offset = bio->bi_iter.bi_bvec_done;
434 bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
435 }
436 atomic_set(&cmd->ref, 2);
437
438 iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq));
439 iter.iov_offset = offset;
440
441 cmd->iocb.ki_pos = pos;
442 cmd->iocb.ki_filp = file;
443 cmd->iocb.ki_complete = lo_rw_aio_complete;
444 cmd->iocb.ki_flags = IOCB_DIRECT;
445 cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
446
447 if (rw == ITER_SOURCE)
448 ret = call_write_iter(file, &cmd->iocb, &iter);
449 else
450 ret = call_read_iter(file, &cmd->iocb, &iter);
451
452 lo_rw_aio_do_completion(cmd);
453
454 if (ret != -EIOCBQUEUED)
455 lo_rw_aio_complete(&cmd->iocb, ret);
456 return 0;
457}
458
459static int do_req_filebacked(struct loop_device *lo, struct request *rq)
460{
461 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
462 loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
463
464 /*
465 * lo_write_simple and lo_read_simple should have been covered
466 * by io submit style function like lo_rw_aio(), one blocker
467 * is that lo_read_simple() need to call flush_dcache_page after
468 * the page is written from kernel, and it isn't easy to handle
469 * this in io submit style function which submits all segments
470 * of the req at one time. And direct read IO doesn't need to
471 * run flush_dcache_page().
472 */
473 switch (req_op(rq)) {
474 case REQ_OP_FLUSH:
475 return lo_req_flush(lo, rq);
476 case REQ_OP_WRITE_ZEROES:
477 /*
478 * If the caller doesn't want deallocation, call zeroout to
479 * write zeroes the range. Otherwise, punch them out.
480 */
481 return lo_fallocate(lo, rq, pos,
482 (rq->cmd_flags & REQ_NOUNMAP) ?
483 FALLOC_FL_ZERO_RANGE :
484 FALLOC_FL_PUNCH_HOLE);
485 case REQ_OP_DISCARD:
486 return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE);
487 case REQ_OP_WRITE:
488 if (cmd->use_aio)
489 return lo_rw_aio(lo, cmd, pos, ITER_SOURCE);
490 else
491 return lo_write_simple(lo, rq, pos);
492 case REQ_OP_READ:
493 if (cmd->use_aio)
494 return lo_rw_aio(lo, cmd, pos, ITER_DEST);
495 else
496 return lo_read_simple(lo, rq, pos);
497 default:
498 WARN_ON_ONCE(1);
499 return -EIO;
500 }
501}
502
503static inline void loop_update_dio(struct loop_device *lo)
504{
505 __loop_update_dio(lo, (lo->lo_backing_file->f_flags & O_DIRECT) |
506 lo->use_dio);
507}
508
509static void loop_reread_partitions(struct loop_device *lo)
510{
511 int rc;
512
513 mutex_lock(&lo->lo_disk->open_mutex);
514 rc = bdev_disk_changed(lo->lo_disk, false);
515 mutex_unlock(&lo->lo_disk->open_mutex);
516 if (rc)
517 pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
518 __func__, lo->lo_number, lo->lo_file_name, rc);
519}
520
521static inline int is_loop_device(struct file *file)
522{
523 struct inode *i = file->f_mapping->host;
524
525 return i && S_ISBLK(i->i_mode) && imajor(i) == LOOP_MAJOR;
526}
527
528static int loop_validate_file(struct file *file, struct block_device *bdev)
529{
530 struct inode *inode = file->f_mapping->host;
531 struct file *f = file;
532
533 /* Avoid recursion */
534 while (is_loop_device(f)) {
535 struct loop_device *l;
536
537 lockdep_assert_held(&loop_validate_mutex);
538 if (f->f_mapping->host->i_rdev == bdev->bd_dev)
539 return -EBADF;
540
541 l = I_BDEV(f->f_mapping->host)->bd_disk->private_data;
542 if (l->lo_state != Lo_bound)
543 return -EINVAL;
544 /* Order wrt setting lo->lo_backing_file in loop_configure(). */
545 rmb();
546 f = l->lo_backing_file;
547 }
548 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
549 return -EINVAL;
550 return 0;
551}
552
553/*
554 * loop_change_fd switched the backing store of a loopback device to
555 * a new file. This is useful for operating system installers to free up
556 * the original file and in High Availability environments to switch to
557 * an alternative location for the content in case of server meltdown.
558 * This can only work if the loop device is used read-only, and if the
559 * new backing store is the same size and type as the old backing store.
560 */
561static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
562 unsigned int arg)
563{
564 struct file *file = fget(arg);
565 struct file *old_file;
566 int error;
567 bool partscan;
568 bool is_loop;
569
570 if (!file)
571 return -EBADF;
572
573 /* suppress uevents while reconfiguring the device */
574 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
575
576 is_loop = is_loop_device(file);
577 error = loop_global_lock_killable(lo, is_loop);
578 if (error)
579 goto out_putf;
580 error = -ENXIO;
581 if (lo->lo_state != Lo_bound)
582 goto out_err;
583
584 /* the loop device has to be read-only */
585 error = -EINVAL;
586 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
587 goto out_err;
588
589 error = loop_validate_file(file, bdev);
590 if (error)
591 goto out_err;
592
593 old_file = lo->lo_backing_file;
594
595 error = -EINVAL;
596
597 /* size of the new backing store needs to be the same */
598 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
599 goto out_err;
600
601 /* and ... switch */
602 disk_force_media_change(lo->lo_disk);
603 blk_mq_freeze_queue(lo->lo_queue);
604 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
605 lo->lo_backing_file = file;
606 lo->old_gfp_mask = mapping_gfp_mask(file->f_mapping);
607 mapping_set_gfp_mask(file->f_mapping,
608 lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
609 loop_update_dio(lo);
610 blk_mq_unfreeze_queue(lo->lo_queue);
611 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
612 loop_global_unlock(lo, is_loop);
613
614 /*
615 * Flush loop_validate_file() before fput(), for l->lo_backing_file
616 * might be pointing at old_file which might be the last reference.
617 */
618 if (!is_loop) {
619 mutex_lock(&loop_validate_mutex);
620 mutex_unlock(&loop_validate_mutex);
621 }
622 /*
623 * We must drop file reference outside of lo_mutex as dropping
624 * the file ref can take open_mutex which creates circular locking
625 * dependency.
626 */
627 fput(old_file);
628 if (partscan)
629 loop_reread_partitions(lo);
630
631 error = 0;
632done:
633 /* enable and uncork uevent now that we are done */
634 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
635 return error;
636
637out_err:
638 loop_global_unlock(lo, is_loop);
639out_putf:
640 fput(file);
641 goto done;
642}
643
644/* loop sysfs attributes */
645
646static ssize_t loop_attr_show(struct device *dev, char *page,
647 ssize_t (*callback)(struct loop_device *, char *))
648{
649 struct gendisk *disk = dev_to_disk(dev);
650 struct loop_device *lo = disk->private_data;
651
652 return callback(lo, page);
653}
654
655#define LOOP_ATTR_RO(_name) \
656static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
657static ssize_t loop_attr_do_show_##_name(struct device *d, \
658 struct device_attribute *attr, char *b) \
659{ \
660 return loop_attr_show(d, b, loop_attr_##_name##_show); \
661} \
662static struct device_attribute loop_attr_##_name = \
663 __ATTR(_name, 0444, loop_attr_do_show_##_name, NULL);
664
665static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
666{
667 ssize_t ret;
668 char *p = NULL;
669
670 spin_lock_irq(&lo->lo_lock);
671 if (lo->lo_backing_file)
672 p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1);
673 spin_unlock_irq(&lo->lo_lock);
674
675 if (IS_ERR_OR_NULL(p))
676 ret = PTR_ERR(p);
677 else {
678 ret = strlen(p);
679 memmove(buf, p, ret);
680 buf[ret++] = '\n';
681 buf[ret] = 0;
682 }
683
684 return ret;
685}
686
687static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
688{
689 return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_offset);
690}
691
692static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
693{
694 return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
695}
696
697static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
698{
699 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
700
701 return sysfs_emit(buf, "%s\n", autoclear ? "1" : "0");
702}
703
704static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
705{
706 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
707
708 return sysfs_emit(buf, "%s\n", partscan ? "1" : "0");
709}
710
711static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf)
712{
713 int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO);
714
715 return sysfs_emit(buf, "%s\n", dio ? "1" : "0");
716}
717
718LOOP_ATTR_RO(backing_file);
719LOOP_ATTR_RO(offset);
720LOOP_ATTR_RO(sizelimit);
721LOOP_ATTR_RO(autoclear);
722LOOP_ATTR_RO(partscan);
723LOOP_ATTR_RO(dio);
724
725static struct attribute *loop_attrs[] = {
726 &loop_attr_backing_file.attr,
727 &loop_attr_offset.attr,
728 &loop_attr_sizelimit.attr,
729 &loop_attr_autoclear.attr,
730 &loop_attr_partscan.attr,
731 &loop_attr_dio.attr,
732 NULL,
733};
734
735static struct attribute_group loop_attribute_group = {
736 .name = "loop",
737 .attrs= loop_attrs,
738};
739
740static void loop_sysfs_init(struct loop_device *lo)
741{
742 lo->sysfs_inited = !sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
743 &loop_attribute_group);
744}
745
746static void loop_sysfs_exit(struct loop_device *lo)
747{
748 if (lo->sysfs_inited)
749 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
750 &loop_attribute_group);
751}
752
753static void loop_config_discard(struct loop_device *lo,
754 struct queue_limits *lim)
755{
756 struct file *file = lo->lo_backing_file;
757 struct inode *inode = file->f_mapping->host;
758 u32 granularity = 0, max_discard_sectors = 0;
759 struct kstatfs sbuf;
760
761 /*
762 * If the backing device is a block device, mirror its zeroing
763 * capability. Set the discard sectors to the block device's zeroing
764 * capabilities because loop discards result in blkdev_issue_zeroout(),
765 * not blkdev_issue_discard(). This maintains consistent behavior with
766 * file-backed loop devices: discarded regions read back as zero.
767 */
768 if (S_ISBLK(inode->i_mode)) {
769 struct request_queue *backingq = bdev_get_queue(I_BDEV(inode));
770
771 max_discard_sectors = backingq->limits.max_write_zeroes_sectors;
772 granularity = bdev_discard_granularity(I_BDEV(inode)) ?:
773 queue_physical_block_size(backingq);
774
775 /*
776 * We use punch hole to reclaim the free space used by the
777 * image a.k.a. discard.
778 */
779 } else if (file->f_op->fallocate && !vfs_statfs(&file->f_path, &sbuf)) {
780 max_discard_sectors = UINT_MAX >> 9;
781 granularity = sbuf.f_bsize;
782 }
783
784 lim->max_hw_discard_sectors = max_discard_sectors;
785 lim->max_write_zeroes_sectors = max_discard_sectors;
786 if (max_discard_sectors)
787 lim->discard_granularity = granularity;
788 else
789 lim->discard_granularity = 0;
790}
791
792struct loop_worker {
793 struct rb_node rb_node;
794 struct work_struct work;
795 struct list_head cmd_list;
796 struct list_head idle_list;
797 struct loop_device *lo;
798 struct cgroup_subsys_state *blkcg_css;
799 unsigned long last_ran_at;
800};
801
802static void loop_workfn(struct work_struct *work);
803
804#ifdef CONFIG_BLK_CGROUP
805static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
806{
807 return !css || css == blkcg_root_css;
808}
809#else
810static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
811{
812 return !css;
813}
814#endif
815
816static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd)
817{
818 struct rb_node **node, *parent = NULL;
819 struct loop_worker *cur_worker, *worker = NULL;
820 struct work_struct *work;
821 struct list_head *cmd_list;
822
823 spin_lock_irq(&lo->lo_work_lock);
824
825 if (queue_on_root_worker(cmd->blkcg_css))
826 goto queue_work;
827
828 node = &lo->worker_tree.rb_node;
829
830 while (*node) {
831 parent = *node;
832 cur_worker = container_of(*node, struct loop_worker, rb_node);
833 if (cur_worker->blkcg_css == cmd->blkcg_css) {
834 worker = cur_worker;
835 break;
836 } else if ((long)cur_worker->blkcg_css < (long)cmd->blkcg_css) {
837 node = &(*node)->rb_left;
838 } else {
839 node = &(*node)->rb_right;
840 }
841 }
842 if (worker)
843 goto queue_work;
844
845 worker = kzalloc(sizeof(struct loop_worker), GFP_NOWAIT | __GFP_NOWARN);
846 /*
847 * In the event we cannot allocate a worker, just queue on the
848 * rootcg worker and issue the I/O as the rootcg
849 */
850 if (!worker) {
851 cmd->blkcg_css = NULL;
852 if (cmd->memcg_css)
853 css_put(cmd->memcg_css);
854 cmd->memcg_css = NULL;
855 goto queue_work;
856 }
857
858 worker->blkcg_css = cmd->blkcg_css;
859 css_get(worker->blkcg_css);
860 INIT_WORK(&worker->work, loop_workfn);
861 INIT_LIST_HEAD(&worker->cmd_list);
862 INIT_LIST_HEAD(&worker->idle_list);
863 worker->lo = lo;
864 rb_link_node(&worker->rb_node, parent, node);
865 rb_insert_color(&worker->rb_node, &lo->worker_tree);
866queue_work:
867 if (worker) {
868 /*
869 * We need to remove from the idle list here while
870 * holding the lock so that the idle timer doesn't
871 * free the worker
872 */
873 if (!list_empty(&worker->idle_list))
874 list_del_init(&worker->idle_list);
875 work = &worker->work;
876 cmd_list = &worker->cmd_list;
877 } else {
878 work = &lo->rootcg_work;
879 cmd_list = &lo->rootcg_cmd_list;
880 }
881 list_add_tail(&cmd->list_entry, cmd_list);
882 queue_work(lo->workqueue, work);
883 spin_unlock_irq(&lo->lo_work_lock);
884}
885
886static void loop_set_timer(struct loop_device *lo)
887{
888 timer_reduce(&lo->timer, jiffies + LOOP_IDLE_WORKER_TIMEOUT);
889}
890
891static void loop_free_idle_workers(struct loop_device *lo, bool delete_all)
892{
893 struct loop_worker *pos, *worker;
894
895 spin_lock_irq(&lo->lo_work_lock);
896 list_for_each_entry_safe(worker, pos, &lo->idle_worker_list,
897 idle_list) {
898 if (!delete_all &&
899 time_is_after_jiffies(worker->last_ran_at +
900 LOOP_IDLE_WORKER_TIMEOUT))
901 break;
902 list_del(&worker->idle_list);
903 rb_erase(&worker->rb_node, &lo->worker_tree);
904 css_put(worker->blkcg_css);
905 kfree(worker);
906 }
907 if (!list_empty(&lo->idle_worker_list))
908 loop_set_timer(lo);
909 spin_unlock_irq(&lo->lo_work_lock);
910}
911
912static void loop_free_idle_workers_timer(struct timer_list *timer)
913{
914 struct loop_device *lo = container_of(timer, struct loop_device, timer);
915
916 return loop_free_idle_workers(lo, false);
917}
918
919static void loop_update_rotational(struct loop_device *lo)
920{
921 struct file *file = lo->lo_backing_file;
922 struct inode *file_inode = file->f_mapping->host;
923 struct block_device *file_bdev = file_inode->i_sb->s_bdev;
924 struct request_queue *q = lo->lo_queue;
925 bool nonrot = true;
926
927 /* not all filesystems (e.g. tmpfs) have a sb->s_bdev */
928 if (file_bdev)
929 nonrot = bdev_nonrot(file_bdev);
930
931 if (nonrot)
932 blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
933 else
934 blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
935}
936
937/**
938 * loop_set_status_from_info - configure device from loop_info
939 * @lo: struct loop_device to configure
940 * @info: struct loop_info64 to configure the device with
941 *
942 * Configures the loop device parameters according to the passed
943 * in loop_info64 configuration.
944 */
945static int
946loop_set_status_from_info(struct loop_device *lo,
947 const struct loop_info64 *info)
948{
949 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
950 return -EINVAL;
951
952 switch (info->lo_encrypt_type) {
953 case LO_CRYPT_NONE:
954 break;
955 case LO_CRYPT_XOR:
956 pr_warn("support for the xor transformation has been removed.\n");
957 return -EINVAL;
958 case LO_CRYPT_CRYPTOAPI:
959 pr_warn("support for cryptoloop has been removed. Use dm-crypt instead.\n");
960 return -EINVAL;
961 default:
962 return -EINVAL;
963 }
964
965 /* Avoid assigning overflow values */
966 if (info->lo_offset > LLONG_MAX || info->lo_sizelimit > LLONG_MAX)
967 return -EOVERFLOW;
968
969 lo->lo_offset = info->lo_offset;
970 lo->lo_sizelimit = info->lo_sizelimit;
971
972 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
973 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
974 lo->lo_flags = info->lo_flags;
975 return 0;
976}
977
978static int loop_reconfigure_limits(struct loop_device *lo, unsigned short bsize,
979 bool update_discard_settings)
980{
981 struct queue_limits lim;
982
983 lim = queue_limits_start_update(lo->lo_queue);
984 lim.logical_block_size = bsize;
985 lim.physical_block_size = bsize;
986 lim.io_min = bsize;
987 if (update_discard_settings)
988 loop_config_discard(lo, &lim);
989 return queue_limits_commit_update(lo->lo_queue, &lim);
990}
991
992static int loop_configure(struct loop_device *lo, blk_mode_t mode,
993 struct block_device *bdev,
994 const struct loop_config *config)
995{
996 struct file *file = fget(config->fd);
997 struct inode *inode;
998 struct address_space *mapping;
999 int error;
1000 loff_t size;
1001 bool partscan;
1002 unsigned short bsize;
1003 bool is_loop;
1004
1005 if (!file)
1006 return -EBADF;
1007 is_loop = is_loop_device(file);
1008
1009 /* This is safe, since we have a reference from open(). */
1010 __module_get(THIS_MODULE);
1011
1012 /*
1013 * If we don't hold exclusive handle for the device, upgrade to it
1014 * here to avoid changing device under exclusive owner.
1015 */
1016 if (!(mode & BLK_OPEN_EXCL)) {
1017 error = bd_prepare_to_claim(bdev, loop_configure, NULL);
1018 if (error)
1019 goto out_putf;
1020 }
1021
1022 error = loop_global_lock_killable(lo, is_loop);
1023 if (error)
1024 goto out_bdev;
1025
1026 error = -EBUSY;
1027 if (lo->lo_state != Lo_unbound)
1028 goto out_unlock;
1029
1030 error = loop_validate_file(file, bdev);
1031 if (error)
1032 goto out_unlock;
1033
1034 mapping = file->f_mapping;
1035 inode = mapping->host;
1036
1037 if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) {
1038 error = -EINVAL;
1039 goto out_unlock;
1040 }
1041
1042 if (config->block_size) {
1043 error = blk_validate_block_size(config->block_size);
1044 if (error)
1045 goto out_unlock;
1046 }
1047
1048 error = loop_set_status_from_info(lo, &config->info);
1049 if (error)
1050 goto out_unlock;
1051
1052 if (!(file->f_mode & FMODE_WRITE) || !(mode & BLK_OPEN_WRITE) ||
1053 !file->f_op->write_iter)
1054 lo->lo_flags |= LO_FLAGS_READ_ONLY;
1055
1056 if (!lo->workqueue) {
1057 lo->workqueue = alloc_workqueue("loop%d",
1058 WQ_UNBOUND | WQ_FREEZABLE,
1059 0, lo->lo_number);
1060 if (!lo->workqueue) {
1061 error = -ENOMEM;
1062 goto out_unlock;
1063 }
1064 }
1065
1066 /* suppress uevents while reconfiguring the device */
1067 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
1068
1069 disk_force_media_change(lo->lo_disk);
1070 set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0);
1071
1072 lo->use_dio = lo->lo_flags & LO_FLAGS_DIRECT_IO;
1073 lo->lo_device = bdev;
1074 lo->lo_backing_file = file;
1075 lo->old_gfp_mask = mapping_gfp_mask(mapping);
1076 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
1077
1078 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
1079 blk_queue_write_cache(lo->lo_queue, true, false);
1080
1081 if (config->block_size)
1082 bsize = config->block_size;
1083 else if ((lo->lo_backing_file->f_flags & O_DIRECT) && inode->i_sb->s_bdev)
1084 /* In case of direct I/O, match underlying block size */
1085 bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
1086 else
1087 bsize = 512;
1088
1089 error = loop_reconfigure_limits(lo, bsize, true);
1090 if (WARN_ON_ONCE(error))
1091 goto out_unlock;
1092
1093 loop_update_rotational(lo);
1094 loop_update_dio(lo);
1095 loop_sysfs_init(lo);
1096
1097 size = get_loop_size(lo, file);
1098 loop_set_size(lo, size);
1099
1100 /* Order wrt reading lo_state in loop_validate_file(). */
1101 wmb();
1102
1103 lo->lo_state = Lo_bound;
1104 if (part_shift)
1105 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1106 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
1107 if (partscan)
1108 clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1109
1110 /* enable and uncork uevent now that we are done */
1111 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
1112
1113 loop_global_unlock(lo, is_loop);
1114 if (partscan)
1115 loop_reread_partitions(lo);
1116
1117 if (!(mode & BLK_OPEN_EXCL))
1118 bd_abort_claiming(bdev, loop_configure);
1119
1120 return 0;
1121
1122out_unlock:
1123 loop_global_unlock(lo, is_loop);
1124out_bdev:
1125 if (!(mode & BLK_OPEN_EXCL))
1126 bd_abort_claiming(bdev, loop_configure);
1127out_putf:
1128 fput(file);
1129 /* This is safe: open() is still holding a reference. */
1130 module_put(THIS_MODULE);
1131 return error;
1132}
1133
1134static void __loop_clr_fd(struct loop_device *lo, bool release)
1135{
1136 struct file *filp;
1137 gfp_t gfp = lo->old_gfp_mask;
1138
1139 if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags))
1140 blk_queue_write_cache(lo->lo_queue, false, false);
1141
1142 /*
1143 * Freeze the request queue when unbinding on a live file descriptor and
1144 * thus an open device. When called from ->release we are guaranteed
1145 * that there is no I/O in progress already.
1146 */
1147 if (!release)
1148 blk_mq_freeze_queue(lo->lo_queue);
1149
1150 spin_lock_irq(&lo->lo_lock);
1151 filp = lo->lo_backing_file;
1152 lo->lo_backing_file = NULL;
1153 spin_unlock_irq(&lo->lo_lock);
1154
1155 lo->lo_device = NULL;
1156 lo->lo_offset = 0;
1157 lo->lo_sizelimit = 0;
1158 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1159 loop_reconfigure_limits(lo, 512, false);
1160 invalidate_disk(lo->lo_disk);
1161 loop_sysfs_exit(lo);
1162 /* let user-space know about this change */
1163 kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
1164 mapping_set_gfp_mask(filp->f_mapping, gfp);
1165 /* This is safe: open() is still holding a reference. */
1166 module_put(THIS_MODULE);
1167 if (!release)
1168 blk_mq_unfreeze_queue(lo->lo_queue);
1169
1170 disk_force_media_change(lo->lo_disk);
1171
1172 if (lo->lo_flags & LO_FLAGS_PARTSCAN) {
1173 int err;
1174
1175 /*
1176 * open_mutex has been held already in release path, so don't
1177 * acquire it if this function is called in such case.
1178 *
1179 * If the reread partition isn't from release path, lo_refcnt
1180 * must be at least one and it can only become zero when the
1181 * current holder is released.
1182 */
1183 if (!release)
1184 mutex_lock(&lo->lo_disk->open_mutex);
1185 err = bdev_disk_changed(lo->lo_disk, false);
1186 if (!release)
1187 mutex_unlock(&lo->lo_disk->open_mutex);
1188 if (err)
1189 pr_warn("%s: partition scan of loop%d failed (rc=%d)\n",
1190 __func__, lo->lo_number, err);
1191 /* Device is gone, no point in returning error */
1192 }
1193
1194 /*
1195 * lo->lo_state is set to Lo_unbound here after above partscan has
1196 * finished. There cannot be anybody else entering __loop_clr_fd() as
1197 * Lo_rundown state protects us from all the other places trying to
1198 * change the 'lo' device.
1199 */
1200 lo->lo_flags = 0;
1201 if (!part_shift)
1202 set_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1203 mutex_lock(&lo->lo_mutex);
1204 lo->lo_state = Lo_unbound;
1205 mutex_unlock(&lo->lo_mutex);
1206
1207 /*
1208 * Need not hold lo_mutex to fput backing file. Calling fput holding
1209 * lo_mutex triggers a circular lock dependency possibility warning as
1210 * fput can take open_mutex which is usually taken before lo_mutex.
1211 */
1212 fput(filp);
1213}
1214
1215static int loop_clr_fd(struct loop_device *lo)
1216{
1217 int err;
1218
1219 /*
1220 * Since lo_ioctl() is called without locks held, it is possible that
1221 * loop_configure()/loop_change_fd() and loop_clr_fd() run in parallel.
1222 *
1223 * Therefore, use global lock when setting Lo_rundown state in order to
1224 * make sure that loop_validate_file() will fail if the "struct file"
1225 * which loop_configure()/loop_change_fd() found via fget() was this
1226 * loop device.
1227 */
1228 err = loop_global_lock_killable(lo, true);
1229 if (err)
1230 return err;
1231 if (lo->lo_state != Lo_bound) {
1232 loop_global_unlock(lo, true);
1233 return -ENXIO;
1234 }
1235 /*
1236 * If we've explicitly asked to tear down the loop device,
1237 * and it has an elevated reference count, set it for auto-teardown when
1238 * the last reference goes away. This stops $!~#$@ udev from
1239 * preventing teardown because it decided that it needs to run blkid on
1240 * the loopback device whenever they appear. xfstests is notorious for
1241 * failing tests because blkid via udev races with a losetup
1242 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
1243 * command to fail with EBUSY.
1244 */
1245 if (disk_openers(lo->lo_disk) > 1) {
1246 lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
1247 loop_global_unlock(lo, true);
1248 return 0;
1249 }
1250 lo->lo_state = Lo_rundown;
1251 loop_global_unlock(lo, true);
1252
1253 __loop_clr_fd(lo, false);
1254 return 0;
1255}
1256
1257static int
1258loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1259{
1260 int err;
1261 int prev_lo_flags;
1262 bool partscan = false;
1263 bool size_changed = false;
1264
1265 err = mutex_lock_killable(&lo->lo_mutex);
1266 if (err)
1267 return err;
1268 if (lo->lo_state != Lo_bound) {
1269 err = -ENXIO;
1270 goto out_unlock;
1271 }
1272
1273 if (lo->lo_offset != info->lo_offset ||
1274 lo->lo_sizelimit != info->lo_sizelimit) {
1275 size_changed = true;
1276 sync_blockdev(lo->lo_device);
1277 invalidate_bdev(lo->lo_device);
1278 }
1279
1280 /* I/O need to be drained during transfer transition */
1281 blk_mq_freeze_queue(lo->lo_queue);
1282
1283 prev_lo_flags = lo->lo_flags;
1284
1285 err = loop_set_status_from_info(lo, info);
1286 if (err)
1287 goto out_unfreeze;
1288
1289 /* Mask out flags that can't be set using LOOP_SET_STATUS. */
1290 lo->lo_flags &= LOOP_SET_STATUS_SETTABLE_FLAGS;
1291 /* For those flags, use the previous values instead */
1292 lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_SETTABLE_FLAGS;
1293 /* For flags that can't be cleared, use previous values too */
1294 lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_CLEARABLE_FLAGS;
1295
1296 if (size_changed) {
1297 loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit,
1298 lo->lo_backing_file);
1299 loop_set_size(lo, new_size);
1300 }
1301
1302 /* update dio if lo_offset or transfer is changed */
1303 __loop_update_dio(lo, lo->use_dio);
1304
1305out_unfreeze:
1306 blk_mq_unfreeze_queue(lo->lo_queue);
1307
1308 if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) &&
1309 !(prev_lo_flags & LO_FLAGS_PARTSCAN)) {
1310 clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1311 partscan = true;
1312 }
1313out_unlock:
1314 mutex_unlock(&lo->lo_mutex);
1315 if (partscan)
1316 loop_reread_partitions(lo);
1317
1318 return err;
1319}
1320
1321static int
1322loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1323{
1324 struct path path;
1325 struct kstat stat;
1326 int ret;
1327
1328 ret = mutex_lock_killable(&lo->lo_mutex);
1329 if (ret)
1330 return ret;
1331 if (lo->lo_state != Lo_bound) {
1332 mutex_unlock(&lo->lo_mutex);
1333 return -ENXIO;
1334 }
1335
1336 memset(info, 0, sizeof(*info));
1337 info->lo_number = lo->lo_number;
1338 info->lo_offset = lo->lo_offset;
1339 info->lo_sizelimit = lo->lo_sizelimit;
1340 info->lo_flags = lo->lo_flags;
1341 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1342
1343 /* Drop lo_mutex while we call into the filesystem. */
1344 path = lo->lo_backing_file->f_path;
1345 path_get(&path);
1346 mutex_unlock(&lo->lo_mutex);
1347 ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT);
1348 if (!ret) {
1349 info->lo_device = huge_encode_dev(stat.dev);
1350 info->lo_inode = stat.ino;
1351 info->lo_rdevice = huge_encode_dev(stat.rdev);
1352 }
1353 path_put(&path);
1354 return ret;
1355}
1356
1357static void
1358loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1359{
1360 memset(info64, 0, sizeof(*info64));
1361 info64->lo_number = info->lo_number;
1362 info64->lo_device = info->lo_device;
1363 info64->lo_inode = info->lo_inode;
1364 info64->lo_rdevice = info->lo_rdevice;
1365 info64->lo_offset = info->lo_offset;
1366 info64->lo_sizelimit = 0;
1367 info64->lo_flags = info->lo_flags;
1368 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1369}
1370
1371static int
1372loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1373{
1374 memset(info, 0, sizeof(*info));
1375 info->lo_number = info64->lo_number;
1376 info->lo_device = info64->lo_device;
1377 info->lo_inode = info64->lo_inode;
1378 info->lo_rdevice = info64->lo_rdevice;
1379 info->lo_offset = info64->lo_offset;
1380 info->lo_flags = info64->lo_flags;
1381 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1382
1383 /* error in case values were truncated */
1384 if (info->lo_device != info64->lo_device ||
1385 info->lo_rdevice != info64->lo_rdevice ||
1386 info->lo_inode != info64->lo_inode ||
1387 info->lo_offset != info64->lo_offset)
1388 return -EOVERFLOW;
1389
1390 return 0;
1391}
1392
1393static int
1394loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1395{
1396 struct loop_info info;
1397 struct loop_info64 info64;
1398
1399 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1400 return -EFAULT;
1401 loop_info64_from_old(&info, &info64);
1402 return loop_set_status(lo, &info64);
1403}
1404
1405static int
1406loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1407{
1408 struct loop_info64 info64;
1409
1410 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1411 return -EFAULT;
1412 return loop_set_status(lo, &info64);
1413}
1414
1415static int
1416loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1417 struct loop_info info;
1418 struct loop_info64 info64;
1419 int err;
1420
1421 if (!arg)
1422 return -EINVAL;
1423 err = loop_get_status(lo, &info64);
1424 if (!err)
1425 err = loop_info64_to_old(&info64, &info);
1426 if (!err && copy_to_user(arg, &info, sizeof(info)))
1427 err = -EFAULT;
1428
1429 return err;
1430}
1431
1432static int
1433loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1434 struct loop_info64 info64;
1435 int err;
1436
1437 if (!arg)
1438 return -EINVAL;
1439 err = loop_get_status(lo, &info64);
1440 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1441 err = -EFAULT;
1442
1443 return err;
1444}
1445
1446static int loop_set_capacity(struct loop_device *lo)
1447{
1448 loff_t size;
1449
1450 if (unlikely(lo->lo_state != Lo_bound))
1451 return -ENXIO;
1452
1453 size = get_loop_size(lo, lo->lo_backing_file);
1454 loop_set_size(lo, size);
1455
1456 return 0;
1457}
1458
1459static int loop_set_dio(struct loop_device *lo, unsigned long arg)
1460{
1461 int error = -ENXIO;
1462 if (lo->lo_state != Lo_bound)
1463 goto out;
1464
1465 __loop_update_dio(lo, !!arg);
1466 if (lo->use_dio == !!arg)
1467 return 0;
1468 error = -EINVAL;
1469 out:
1470 return error;
1471}
1472
1473static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
1474{
1475 int err = 0;
1476
1477 if (lo->lo_state != Lo_bound)
1478 return -ENXIO;
1479
1480 err = blk_validate_block_size(arg);
1481 if (err)
1482 return err;
1483
1484 if (lo->lo_queue->limits.logical_block_size == arg)
1485 return 0;
1486
1487 sync_blockdev(lo->lo_device);
1488 invalidate_bdev(lo->lo_device);
1489
1490 blk_mq_freeze_queue(lo->lo_queue);
1491 err = loop_reconfigure_limits(lo, arg, false);
1492 loop_update_dio(lo);
1493 blk_mq_unfreeze_queue(lo->lo_queue);
1494
1495 return err;
1496}
1497
1498static int lo_simple_ioctl(struct loop_device *lo, unsigned int cmd,
1499 unsigned long arg)
1500{
1501 int err;
1502
1503 err = mutex_lock_killable(&lo->lo_mutex);
1504 if (err)
1505 return err;
1506 switch (cmd) {
1507 case LOOP_SET_CAPACITY:
1508 err = loop_set_capacity(lo);
1509 break;
1510 case LOOP_SET_DIRECT_IO:
1511 err = loop_set_dio(lo, arg);
1512 break;
1513 case LOOP_SET_BLOCK_SIZE:
1514 err = loop_set_block_size(lo, arg);
1515 break;
1516 default:
1517 err = -EINVAL;
1518 }
1519 mutex_unlock(&lo->lo_mutex);
1520 return err;
1521}
1522
1523static int lo_ioctl(struct block_device *bdev, blk_mode_t mode,
1524 unsigned int cmd, unsigned long arg)
1525{
1526 struct loop_device *lo = bdev->bd_disk->private_data;
1527 void __user *argp = (void __user *) arg;
1528 int err;
1529
1530 switch (cmd) {
1531 case LOOP_SET_FD: {
1532 /*
1533 * Legacy case - pass in a zeroed out struct loop_config with
1534 * only the file descriptor set , which corresponds with the
1535 * default parameters we'd have used otherwise.
1536 */
1537 struct loop_config config;
1538
1539 memset(&config, 0, sizeof(config));
1540 config.fd = arg;
1541
1542 return loop_configure(lo, mode, bdev, &config);
1543 }
1544 case LOOP_CONFIGURE: {
1545 struct loop_config config;
1546
1547 if (copy_from_user(&config, argp, sizeof(config)))
1548 return -EFAULT;
1549
1550 return loop_configure(lo, mode, bdev, &config);
1551 }
1552 case LOOP_CHANGE_FD:
1553 return loop_change_fd(lo, bdev, arg);
1554 case LOOP_CLR_FD:
1555 return loop_clr_fd(lo);
1556 case LOOP_SET_STATUS:
1557 err = -EPERM;
1558 if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN))
1559 err = loop_set_status_old(lo, argp);
1560 break;
1561 case LOOP_GET_STATUS:
1562 return loop_get_status_old(lo, argp);
1563 case LOOP_SET_STATUS64:
1564 err = -EPERM;
1565 if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN))
1566 err = loop_set_status64(lo, argp);
1567 break;
1568 case LOOP_GET_STATUS64:
1569 return loop_get_status64(lo, argp);
1570 case LOOP_SET_CAPACITY:
1571 case LOOP_SET_DIRECT_IO:
1572 case LOOP_SET_BLOCK_SIZE:
1573 if (!(mode & BLK_OPEN_WRITE) && !capable(CAP_SYS_ADMIN))
1574 return -EPERM;
1575 fallthrough;
1576 default:
1577 err = lo_simple_ioctl(lo, cmd, arg);
1578 break;
1579 }
1580
1581 return err;
1582}
1583
1584#ifdef CONFIG_COMPAT
1585struct compat_loop_info {
1586 compat_int_t lo_number; /* ioctl r/o */
1587 compat_dev_t lo_device; /* ioctl r/o */
1588 compat_ulong_t lo_inode; /* ioctl r/o */
1589 compat_dev_t lo_rdevice; /* ioctl r/o */
1590 compat_int_t lo_offset;
1591 compat_int_t lo_encrypt_type; /* obsolete, ignored */
1592 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1593 compat_int_t lo_flags; /* ioctl r/o */
1594 char lo_name[LO_NAME_SIZE];
1595 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1596 compat_ulong_t lo_init[2];
1597 char reserved[4];
1598};
1599
1600/*
1601 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1602 * - noinlined to reduce stack space usage in main part of driver
1603 */
1604static noinline int
1605loop_info64_from_compat(const struct compat_loop_info __user *arg,
1606 struct loop_info64 *info64)
1607{
1608 struct compat_loop_info info;
1609
1610 if (copy_from_user(&info, arg, sizeof(info)))
1611 return -EFAULT;
1612
1613 memset(info64, 0, sizeof(*info64));
1614 info64->lo_number = info.lo_number;
1615 info64->lo_device = info.lo_device;
1616 info64->lo_inode = info.lo_inode;
1617 info64->lo_rdevice = info.lo_rdevice;
1618 info64->lo_offset = info.lo_offset;
1619 info64->lo_sizelimit = 0;
1620 info64->lo_flags = info.lo_flags;
1621 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1622 return 0;
1623}
1624
1625/*
1626 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1627 * - noinlined to reduce stack space usage in main part of driver
1628 */
1629static noinline int
1630loop_info64_to_compat(const struct loop_info64 *info64,
1631 struct compat_loop_info __user *arg)
1632{
1633 struct compat_loop_info info;
1634
1635 memset(&info, 0, sizeof(info));
1636 info.lo_number = info64->lo_number;
1637 info.lo_device = info64->lo_device;
1638 info.lo_inode = info64->lo_inode;
1639 info.lo_rdevice = info64->lo_rdevice;
1640 info.lo_offset = info64->lo_offset;
1641 info.lo_flags = info64->lo_flags;
1642 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1643
1644 /* error in case values were truncated */
1645 if (info.lo_device != info64->lo_device ||
1646 info.lo_rdevice != info64->lo_rdevice ||
1647 info.lo_inode != info64->lo_inode ||
1648 info.lo_offset != info64->lo_offset)
1649 return -EOVERFLOW;
1650
1651 if (copy_to_user(arg, &info, sizeof(info)))
1652 return -EFAULT;
1653 return 0;
1654}
1655
1656static int
1657loop_set_status_compat(struct loop_device *lo,
1658 const struct compat_loop_info __user *arg)
1659{
1660 struct loop_info64 info64;
1661 int ret;
1662
1663 ret = loop_info64_from_compat(arg, &info64);
1664 if (ret < 0)
1665 return ret;
1666 return loop_set_status(lo, &info64);
1667}
1668
1669static int
1670loop_get_status_compat(struct loop_device *lo,
1671 struct compat_loop_info __user *arg)
1672{
1673 struct loop_info64 info64;
1674 int err;
1675
1676 if (!arg)
1677 return -EINVAL;
1678 err = loop_get_status(lo, &info64);
1679 if (!err)
1680 err = loop_info64_to_compat(&info64, arg);
1681 return err;
1682}
1683
1684static int lo_compat_ioctl(struct block_device *bdev, blk_mode_t mode,
1685 unsigned int cmd, unsigned long arg)
1686{
1687 struct loop_device *lo = bdev->bd_disk->private_data;
1688 int err;
1689
1690 switch(cmd) {
1691 case LOOP_SET_STATUS:
1692 err = loop_set_status_compat(lo,
1693 (const struct compat_loop_info __user *)arg);
1694 break;
1695 case LOOP_GET_STATUS:
1696 err = loop_get_status_compat(lo,
1697 (struct compat_loop_info __user *)arg);
1698 break;
1699 case LOOP_SET_CAPACITY:
1700 case LOOP_CLR_FD:
1701 case LOOP_GET_STATUS64:
1702 case LOOP_SET_STATUS64:
1703 case LOOP_CONFIGURE:
1704 arg = (unsigned long) compat_ptr(arg);
1705 fallthrough;
1706 case LOOP_SET_FD:
1707 case LOOP_CHANGE_FD:
1708 case LOOP_SET_BLOCK_SIZE:
1709 case LOOP_SET_DIRECT_IO:
1710 err = lo_ioctl(bdev, mode, cmd, arg);
1711 break;
1712 default:
1713 err = -ENOIOCTLCMD;
1714 break;
1715 }
1716 return err;
1717}
1718#endif
1719
1720static void lo_release(struct gendisk *disk)
1721{
1722 struct loop_device *lo = disk->private_data;
1723
1724 if (disk_openers(disk) > 0)
1725 return;
1726
1727 mutex_lock(&lo->lo_mutex);
1728 if (lo->lo_state == Lo_bound && (lo->lo_flags & LO_FLAGS_AUTOCLEAR)) {
1729 lo->lo_state = Lo_rundown;
1730 mutex_unlock(&lo->lo_mutex);
1731 /*
1732 * In autoclear mode, stop the loop thread
1733 * and remove configuration after last close.
1734 */
1735 __loop_clr_fd(lo, true);
1736 return;
1737 }
1738 mutex_unlock(&lo->lo_mutex);
1739}
1740
1741static void lo_free_disk(struct gendisk *disk)
1742{
1743 struct loop_device *lo = disk->private_data;
1744
1745 if (lo->workqueue)
1746 destroy_workqueue(lo->workqueue);
1747 loop_free_idle_workers(lo, true);
1748 timer_shutdown_sync(&lo->timer);
1749 mutex_destroy(&lo->lo_mutex);
1750 kfree(lo);
1751}
1752
1753static const struct block_device_operations lo_fops = {
1754 .owner = THIS_MODULE,
1755 .release = lo_release,
1756 .ioctl = lo_ioctl,
1757#ifdef CONFIG_COMPAT
1758 .compat_ioctl = lo_compat_ioctl,
1759#endif
1760 .free_disk = lo_free_disk,
1761};
1762
1763/*
1764 * And now the modules code and kernel interface.
1765 */
1766
1767/*
1768 * If max_loop is specified, create that many devices upfront.
1769 * This also becomes a hard limit. If max_loop is not specified,
1770 * the default isn't a hard limit (as before commit 85c50197716c
1771 * changed the default value from 0 for max_loop=0 reasons), just
1772 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1773 * init time. Loop devices can be requested on-demand with the
1774 * /dev/loop-control interface, or be instantiated by accessing
1775 * a 'dead' device node.
1776 */
1777static int max_loop = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1778
1779#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
1780static bool max_loop_specified;
1781
1782static int max_loop_param_set_int(const char *val,
1783 const struct kernel_param *kp)
1784{
1785 int ret;
1786
1787 ret = param_set_int(val, kp);
1788 if (ret < 0)
1789 return ret;
1790
1791 max_loop_specified = true;
1792 return 0;
1793}
1794
1795static const struct kernel_param_ops max_loop_param_ops = {
1796 .set = max_loop_param_set_int,
1797 .get = param_get_int,
1798};
1799
1800module_param_cb(max_loop, &max_loop_param_ops, &max_loop, 0444);
1801MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1802#else
1803module_param(max_loop, int, 0444);
1804MODULE_PARM_DESC(max_loop, "Initial number of loop devices");
1805#endif
1806
1807module_param(max_part, int, 0444);
1808MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1809
1810static int hw_queue_depth = LOOP_DEFAULT_HW_Q_DEPTH;
1811
1812static int loop_set_hw_queue_depth(const char *s, const struct kernel_param *p)
1813{
1814 int qd, ret;
1815
1816 ret = kstrtoint(s, 0, &qd);
1817 if (ret < 0)
1818 return ret;
1819 if (qd < 1)
1820 return -EINVAL;
1821 hw_queue_depth = qd;
1822 return 0;
1823}
1824
1825static const struct kernel_param_ops loop_hw_qdepth_param_ops = {
1826 .set = loop_set_hw_queue_depth,
1827 .get = param_get_int,
1828};
1829
1830device_param_cb(hw_queue_depth, &loop_hw_qdepth_param_ops, &hw_queue_depth, 0444);
1831MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: " __stringify(LOOP_DEFAULT_HW_Q_DEPTH));
1832
1833MODULE_LICENSE("GPL");
1834MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1835
1836static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
1837 const struct blk_mq_queue_data *bd)
1838{
1839 struct request *rq = bd->rq;
1840 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
1841 struct loop_device *lo = rq->q->queuedata;
1842
1843 blk_mq_start_request(rq);
1844
1845 if (lo->lo_state != Lo_bound)
1846 return BLK_STS_IOERR;
1847
1848 switch (req_op(rq)) {
1849 case REQ_OP_FLUSH:
1850 case REQ_OP_DISCARD:
1851 case REQ_OP_WRITE_ZEROES:
1852 cmd->use_aio = false;
1853 break;
1854 default:
1855 cmd->use_aio = lo->use_dio;
1856 break;
1857 }
1858
1859 /* always use the first bio's css */
1860 cmd->blkcg_css = NULL;
1861 cmd->memcg_css = NULL;
1862#ifdef CONFIG_BLK_CGROUP
1863 if (rq->bio) {
1864 cmd->blkcg_css = bio_blkcg_css(rq->bio);
1865#ifdef CONFIG_MEMCG
1866 if (cmd->blkcg_css) {
1867 cmd->memcg_css =
1868 cgroup_get_e_css(cmd->blkcg_css->cgroup,
1869 &memory_cgrp_subsys);
1870 }
1871#endif
1872 }
1873#endif
1874 loop_queue_work(lo, cmd);
1875
1876 return BLK_STS_OK;
1877}
1878
1879static void loop_handle_cmd(struct loop_cmd *cmd)
1880{
1881 struct cgroup_subsys_state *cmd_blkcg_css = cmd->blkcg_css;
1882 struct cgroup_subsys_state *cmd_memcg_css = cmd->memcg_css;
1883 struct request *rq = blk_mq_rq_from_pdu(cmd);
1884 const bool write = op_is_write(req_op(rq));
1885 struct loop_device *lo = rq->q->queuedata;
1886 int ret = 0;
1887 struct mem_cgroup *old_memcg = NULL;
1888 const bool use_aio = cmd->use_aio;
1889
1890 if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) {
1891 ret = -EIO;
1892 goto failed;
1893 }
1894
1895 if (cmd_blkcg_css)
1896 kthread_associate_blkcg(cmd_blkcg_css);
1897 if (cmd_memcg_css)
1898 old_memcg = set_active_memcg(
1899 mem_cgroup_from_css(cmd_memcg_css));
1900
1901 /*
1902 * do_req_filebacked() may call blk_mq_complete_request() synchronously
1903 * or asynchronously if using aio. Hence, do not touch 'cmd' after
1904 * do_req_filebacked() has returned unless we are sure that 'cmd' has
1905 * not yet been completed.
1906 */
1907 ret = do_req_filebacked(lo, rq);
1908
1909 if (cmd_blkcg_css)
1910 kthread_associate_blkcg(NULL);
1911
1912 if (cmd_memcg_css) {
1913 set_active_memcg(old_memcg);
1914 css_put(cmd_memcg_css);
1915 }
1916 failed:
1917 /* complete non-aio request */
1918 if (!use_aio || ret) {
1919 if (ret == -EOPNOTSUPP)
1920 cmd->ret = ret;
1921 else
1922 cmd->ret = ret ? -EIO : 0;
1923 if (likely(!blk_should_fake_timeout(rq->q)))
1924 blk_mq_complete_request(rq);
1925 }
1926}
1927
1928static void loop_process_work(struct loop_worker *worker,
1929 struct list_head *cmd_list, struct loop_device *lo)
1930{
1931 int orig_flags = current->flags;
1932 struct loop_cmd *cmd;
1933
1934 current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO;
1935 spin_lock_irq(&lo->lo_work_lock);
1936 while (!list_empty(cmd_list)) {
1937 cmd = container_of(
1938 cmd_list->next, struct loop_cmd, list_entry);
1939 list_del(cmd_list->next);
1940 spin_unlock_irq(&lo->lo_work_lock);
1941
1942 loop_handle_cmd(cmd);
1943 cond_resched();
1944
1945 spin_lock_irq(&lo->lo_work_lock);
1946 }
1947
1948 /*
1949 * We only add to the idle list if there are no pending cmds
1950 * *and* the worker will not run again which ensures that it
1951 * is safe to free any worker on the idle list
1952 */
1953 if (worker && !work_pending(&worker->work)) {
1954 worker->last_ran_at = jiffies;
1955 list_add_tail(&worker->idle_list, &lo->idle_worker_list);
1956 loop_set_timer(lo);
1957 }
1958 spin_unlock_irq(&lo->lo_work_lock);
1959 current->flags = orig_flags;
1960}
1961
1962static void loop_workfn(struct work_struct *work)
1963{
1964 struct loop_worker *worker =
1965 container_of(work, struct loop_worker, work);
1966 loop_process_work(worker, &worker->cmd_list, worker->lo);
1967}
1968
1969static void loop_rootcg_workfn(struct work_struct *work)
1970{
1971 struct loop_device *lo =
1972 container_of(work, struct loop_device, rootcg_work);
1973 loop_process_work(NULL, &lo->rootcg_cmd_list, lo);
1974}
1975
1976static const struct blk_mq_ops loop_mq_ops = {
1977 .queue_rq = loop_queue_rq,
1978 .complete = lo_complete_rq,
1979};
1980
1981static int loop_add(int i)
1982{
1983 struct queue_limits lim = {
1984 /*
1985 * Random number picked from the historic block max_sectors cap.
1986 */
1987 .max_hw_sectors = 2560u,
1988 };
1989 struct loop_device *lo;
1990 struct gendisk *disk;
1991 int err;
1992
1993 err = -ENOMEM;
1994 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1995 if (!lo)
1996 goto out;
1997 lo->worker_tree = RB_ROOT;
1998 INIT_LIST_HEAD(&lo->idle_worker_list);
1999 timer_setup(&lo->timer, loop_free_idle_workers_timer, TIMER_DEFERRABLE);
2000 lo->lo_state = Lo_unbound;
2001
2002 err = mutex_lock_killable(&loop_ctl_mutex);
2003 if (err)
2004 goto out_free_dev;
2005
2006 /* allocate id, if @id >= 0, we're requesting that specific id */
2007 if (i >= 0) {
2008 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
2009 if (err == -ENOSPC)
2010 err = -EEXIST;
2011 } else {
2012 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
2013 }
2014 mutex_unlock(&loop_ctl_mutex);
2015 if (err < 0)
2016 goto out_free_dev;
2017 i = err;
2018
2019 lo->tag_set.ops = &loop_mq_ops;
2020 lo->tag_set.nr_hw_queues = 1;
2021 lo->tag_set.queue_depth = hw_queue_depth;
2022 lo->tag_set.numa_node = NUMA_NO_NODE;
2023 lo->tag_set.cmd_size = sizeof(struct loop_cmd);
2024 lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING |
2025 BLK_MQ_F_NO_SCHED_BY_DEFAULT;
2026 lo->tag_set.driver_data = lo;
2027
2028 err = blk_mq_alloc_tag_set(&lo->tag_set);
2029 if (err)
2030 goto out_free_idr;
2031
2032 disk = lo->lo_disk = blk_mq_alloc_disk(&lo->tag_set, &lim, lo);
2033 if (IS_ERR(disk)) {
2034 err = PTR_ERR(disk);
2035 goto out_cleanup_tags;
2036 }
2037 lo->lo_queue = lo->lo_disk->queue;
2038
2039 /*
2040 * By default, we do buffer IO, so it doesn't make sense to enable
2041 * merge because the I/O submitted to backing file is handled page by
2042 * page. For directio mode, merge does help to dispatch bigger request
2043 * to underlayer disk. We will enable merge once directio is enabled.
2044 */
2045 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
2046
2047 /*
2048 * Disable partition scanning by default. The in-kernel partition
2049 * scanning can be requested individually per-device during its
2050 * setup. Userspace can always add and remove partitions from all
2051 * devices. The needed partition minors are allocated from the
2052 * extended minor space, the main loop device numbers will continue
2053 * to match the loop minors, regardless of the number of partitions
2054 * used.
2055 *
2056 * If max_part is given, partition scanning is globally enabled for
2057 * all loop devices. The minors for the main loop devices will be
2058 * multiples of max_part.
2059 *
2060 * Note: Global-for-all-devices, set-only-at-init, read-only module
2061 * parameteters like 'max_loop' and 'max_part' make things needlessly
2062 * complicated, are too static, inflexible and may surprise
2063 * userspace tools. Parameters like this in general should be avoided.
2064 */
2065 if (!part_shift)
2066 set_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
2067 mutex_init(&lo->lo_mutex);
2068 lo->lo_number = i;
2069 spin_lock_init(&lo->lo_lock);
2070 spin_lock_init(&lo->lo_work_lock);
2071 INIT_WORK(&lo->rootcg_work, loop_rootcg_workfn);
2072 INIT_LIST_HEAD(&lo->rootcg_cmd_list);
2073 disk->major = LOOP_MAJOR;
2074 disk->first_minor = i << part_shift;
2075 disk->minors = 1 << part_shift;
2076 disk->fops = &lo_fops;
2077 disk->private_data = lo;
2078 disk->queue = lo->lo_queue;
2079 disk->events = DISK_EVENT_MEDIA_CHANGE;
2080 disk->event_flags = DISK_EVENT_FLAG_UEVENT;
2081 sprintf(disk->disk_name, "loop%d", i);
2082 /* Make this loop device reachable from pathname. */
2083 err = add_disk(disk);
2084 if (err)
2085 goto out_cleanup_disk;
2086
2087 /* Show this loop device. */
2088 mutex_lock(&loop_ctl_mutex);
2089 lo->idr_visible = true;
2090 mutex_unlock(&loop_ctl_mutex);
2091
2092 return i;
2093
2094out_cleanup_disk:
2095 put_disk(disk);
2096out_cleanup_tags:
2097 blk_mq_free_tag_set(&lo->tag_set);
2098out_free_idr:
2099 mutex_lock(&loop_ctl_mutex);
2100 idr_remove(&loop_index_idr, i);
2101 mutex_unlock(&loop_ctl_mutex);
2102out_free_dev:
2103 kfree(lo);
2104out:
2105 return err;
2106}
2107
2108static void loop_remove(struct loop_device *lo)
2109{
2110 /* Make this loop device unreachable from pathname. */
2111 del_gendisk(lo->lo_disk);
2112 blk_mq_free_tag_set(&lo->tag_set);
2113
2114 mutex_lock(&loop_ctl_mutex);
2115 idr_remove(&loop_index_idr, lo->lo_number);
2116 mutex_unlock(&loop_ctl_mutex);
2117
2118 put_disk(lo->lo_disk);
2119}
2120
2121#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
2122static void loop_probe(dev_t dev)
2123{
2124 int idx = MINOR(dev) >> part_shift;
2125
2126 if (max_loop_specified && max_loop && idx >= max_loop)
2127 return;
2128 loop_add(idx);
2129}
2130#else
2131#define loop_probe NULL
2132#endif /* !CONFIG_BLOCK_LEGACY_AUTOLOAD */
2133
2134static int loop_control_remove(int idx)
2135{
2136 struct loop_device *lo;
2137 int ret;
2138
2139 if (idx < 0) {
2140 pr_warn_once("deleting an unspecified loop device is not supported.\n");
2141 return -EINVAL;
2142 }
2143
2144 /* Hide this loop device for serialization. */
2145 ret = mutex_lock_killable(&loop_ctl_mutex);
2146 if (ret)
2147 return ret;
2148 lo = idr_find(&loop_index_idr, idx);
2149 if (!lo || !lo->idr_visible)
2150 ret = -ENODEV;
2151 else
2152 lo->idr_visible = false;
2153 mutex_unlock(&loop_ctl_mutex);
2154 if (ret)
2155 return ret;
2156
2157 /* Check whether this loop device can be removed. */
2158 ret = mutex_lock_killable(&lo->lo_mutex);
2159 if (ret)
2160 goto mark_visible;
2161 if (lo->lo_state != Lo_unbound || disk_openers(lo->lo_disk) > 0) {
2162 mutex_unlock(&lo->lo_mutex);
2163 ret = -EBUSY;
2164 goto mark_visible;
2165 }
2166 /* Mark this loop device as no more bound, but not quite unbound yet */
2167 lo->lo_state = Lo_deleting;
2168 mutex_unlock(&lo->lo_mutex);
2169
2170 loop_remove(lo);
2171 return 0;
2172
2173mark_visible:
2174 /* Show this loop device again. */
2175 mutex_lock(&loop_ctl_mutex);
2176 lo->idr_visible = true;
2177 mutex_unlock(&loop_ctl_mutex);
2178 return ret;
2179}
2180
2181static int loop_control_get_free(int idx)
2182{
2183 struct loop_device *lo;
2184 int id, ret;
2185
2186 ret = mutex_lock_killable(&loop_ctl_mutex);
2187 if (ret)
2188 return ret;
2189 idr_for_each_entry(&loop_index_idr, lo, id) {
2190 /* Hitting a race results in creating a new loop device which is harmless. */
2191 if (lo->idr_visible && data_race(lo->lo_state) == Lo_unbound)
2192 goto found;
2193 }
2194 mutex_unlock(&loop_ctl_mutex);
2195 return loop_add(-1);
2196found:
2197 mutex_unlock(&loop_ctl_mutex);
2198 return id;
2199}
2200
2201static long loop_control_ioctl(struct file *file, unsigned int cmd,
2202 unsigned long parm)
2203{
2204 switch (cmd) {
2205 case LOOP_CTL_ADD:
2206 return loop_add(parm);
2207 case LOOP_CTL_REMOVE:
2208 return loop_control_remove(parm);
2209 case LOOP_CTL_GET_FREE:
2210 return loop_control_get_free(parm);
2211 default:
2212 return -ENOSYS;
2213 }
2214}
2215
2216static const struct file_operations loop_ctl_fops = {
2217 .open = nonseekable_open,
2218 .unlocked_ioctl = loop_control_ioctl,
2219 .compat_ioctl = loop_control_ioctl,
2220 .owner = THIS_MODULE,
2221 .llseek = noop_llseek,
2222};
2223
2224static struct miscdevice loop_misc = {
2225 .minor = LOOP_CTRL_MINOR,
2226 .name = "loop-control",
2227 .fops = &loop_ctl_fops,
2228};
2229
2230MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
2231MODULE_ALIAS("devname:loop-control");
2232
2233static int __init loop_init(void)
2234{
2235 int i;
2236 int err;
2237
2238 part_shift = 0;
2239 if (max_part > 0) {
2240 part_shift = fls(max_part);
2241
2242 /*
2243 * Adjust max_part according to part_shift as it is exported
2244 * to user space so that user can decide correct minor number
2245 * if [s]he want to create more devices.
2246 *
2247 * Note that -1 is required because partition 0 is reserved
2248 * for the whole disk.
2249 */
2250 max_part = (1UL << part_shift) - 1;
2251 }
2252
2253 if ((1UL << part_shift) > DISK_MAX_PARTS) {
2254 err = -EINVAL;
2255 goto err_out;
2256 }
2257
2258 if (max_loop > 1UL << (MINORBITS - part_shift)) {
2259 err = -EINVAL;
2260 goto err_out;
2261 }
2262
2263 err = misc_register(&loop_misc);
2264 if (err < 0)
2265 goto err_out;
2266
2267
2268 if (__register_blkdev(LOOP_MAJOR, "loop", loop_probe)) {
2269 err = -EIO;
2270 goto misc_out;
2271 }
2272
2273 /* pre-create number of devices given by config or max_loop */
2274 for (i = 0; i < max_loop; i++)
2275 loop_add(i);
2276
2277 printk(KERN_INFO "loop: module loaded\n");
2278 return 0;
2279
2280misc_out:
2281 misc_deregister(&loop_misc);
2282err_out:
2283 return err;
2284}
2285
2286static void __exit loop_exit(void)
2287{
2288 struct loop_device *lo;
2289 int id;
2290
2291 unregister_blkdev(LOOP_MAJOR, "loop");
2292 misc_deregister(&loop_misc);
2293
2294 /*
2295 * There is no need to use loop_ctl_mutex here, for nobody else can
2296 * access loop_index_idr when this module is unloading (unless forced
2297 * module unloading is requested). If this is not a clean unloading,
2298 * we have no means to avoid kernel crash.
2299 */
2300 idr_for_each_entry(&loop_index_idr, lo, id)
2301 loop_remove(lo);
2302
2303 idr_destroy(&loop_index_idr);
2304}
2305
2306module_init(loop_init);
2307module_exit(loop_exit);
2308
2309#ifndef MODULE
2310static int __init max_loop_setup(char *str)
2311{
2312 max_loop = simple_strtol(str, NULL, 0);
2313#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
2314 max_loop_specified = true;
2315#endif
2316 return 1;
2317}
2318
2319__setup("max_loop=", max_loop_setup);
2320#endif
1/*
2 * linux/drivers/block/loop.c
3 *
4 * Written by Theodore Ts'o, 3/29/93
5 *
6 * Copyright 1993 by Theodore Ts'o. Redistribution of this file is
7 * permitted under the GNU General Public License.
8 *
9 * DES encryption plus some minor changes by Werner Almesberger, 30-MAY-1993
10 * more DES encryption plus IDEA encryption by Nicholas J. Leon, June 20, 1996
11 *
12 * Modularized and updated for 1.1.16 kernel - Mitch Dsouza 28th May 1994
13 * Adapted for 1.3.59 kernel - Andries Brouwer, 1 Feb 1996
14 *
15 * Fixed do_loop_request() re-entrancy - Vincent.Renardias@waw.com Mar 20, 1997
16 *
17 * Added devfs support - Richard Gooch <rgooch@atnf.csiro.au> 16-Jan-1998
18 *
19 * Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998
20 *
21 * Loadable modules and other fixes by AK, 1998
22 *
23 * Make real block number available to downstream transfer functions, enables
24 * CBC (and relatives) mode encryption requiring unique IVs per data block.
25 * Reed H. Petty, rhp@draper.net
26 *
27 * Maximum number of loop devices now dynamic via max_loop module parameter.
28 * Russell Kroll <rkroll@exploits.org> 19990701
29 *
30 * Maximum number of loop devices when compiled-in now selectable by passing
31 * max_loop=<1-255> to the kernel on boot.
32 * Erik I. Bolsø, <eriki@himolde.no>, Oct 31, 1999
33 *
34 * Completely rewrite request handling to be make_request_fn style and
35 * non blocking, pushing work to a helper thread. Lots of fixes from
36 * Al Viro too.
37 * Jens Axboe <axboe@suse.de>, Nov 2000
38 *
39 * Support up to 256 loop devices
40 * Heinz Mauelshagen <mge@sistina.com>, Feb 2002
41 *
42 * Support for falling back on the write file operation when the address space
43 * operations write_begin is not available on the backing filesystem.
44 * Anton Altaparmakov, 16 Feb 2005
45 *
46 * Still To Fix:
47 * - Advisory locking is ignored here.
48 * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
49 *
50 */
51
52#include <linux/module.h>
53#include <linux/moduleparam.h>
54#include <linux/sched.h>
55#include <linux/fs.h>
56#include <linux/file.h>
57#include <linux/stat.h>
58#include <linux/errno.h>
59#include <linux/major.h>
60#include <linux/wait.h>
61#include <linux/blkdev.h>
62#include <linux/blkpg.h>
63#include <linux/init.h>
64#include <linux/swap.h>
65#include <linux/slab.h>
66#include <linux/compat.h>
67#include <linux/suspend.h>
68#include <linux/freezer.h>
69#include <linux/mutex.h>
70#include <linux/writeback.h>
71#include <linux/completion.h>
72#include <linux/highmem.h>
73#include <linux/kthread.h>
74#include <linux/splice.h>
75#include <linux/sysfs.h>
76#include <linux/miscdevice.h>
77#include <linux/falloc.h>
78#include "loop.h"
79
80#include <asm/uaccess.h>
81
82static DEFINE_IDR(loop_index_idr);
83static DEFINE_MUTEX(loop_index_mutex);
84
85static int max_part;
86static int part_shift;
87
88/*
89 * Transfer functions
90 */
91static int transfer_none(struct loop_device *lo, int cmd,
92 struct page *raw_page, unsigned raw_off,
93 struct page *loop_page, unsigned loop_off,
94 int size, sector_t real_block)
95{
96 char *raw_buf = kmap_atomic(raw_page) + raw_off;
97 char *loop_buf = kmap_atomic(loop_page) + loop_off;
98
99 if (cmd == READ)
100 memcpy(loop_buf, raw_buf, size);
101 else
102 memcpy(raw_buf, loop_buf, size);
103
104 kunmap_atomic(loop_buf);
105 kunmap_atomic(raw_buf);
106 cond_resched();
107 return 0;
108}
109
110static int transfer_xor(struct loop_device *lo, int cmd,
111 struct page *raw_page, unsigned raw_off,
112 struct page *loop_page, unsigned loop_off,
113 int size, sector_t real_block)
114{
115 char *raw_buf = kmap_atomic(raw_page) + raw_off;
116 char *loop_buf = kmap_atomic(loop_page) + loop_off;
117 char *in, *out, *key;
118 int i, keysize;
119
120 if (cmd == READ) {
121 in = raw_buf;
122 out = loop_buf;
123 } else {
124 in = loop_buf;
125 out = raw_buf;
126 }
127
128 key = lo->lo_encrypt_key;
129 keysize = lo->lo_encrypt_key_size;
130 for (i = 0; i < size; i++)
131 *out++ = *in++ ^ key[(i & 511) % keysize];
132
133 kunmap_atomic(loop_buf);
134 kunmap_atomic(raw_buf);
135 cond_resched();
136 return 0;
137}
138
139static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
140{
141 if (unlikely(info->lo_encrypt_key_size <= 0))
142 return -EINVAL;
143 return 0;
144}
145
146static struct loop_func_table none_funcs = {
147 .number = LO_CRYPT_NONE,
148 .transfer = transfer_none,
149};
150
151static struct loop_func_table xor_funcs = {
152 .number = LO_CRYPT_XOR,
153 .transfer = transfer_xor,
154 .init = xor_init
155};
156
157/* xfer_funcs[0] is special - its release function is never called */
158static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
159 &none_funcs,
160 &xor_funcs
161};
162
163static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
164{
165 loff_t loopsize;
166
167 /* Compute loopsize in bytes */
168 loopsize = i_size_read(file->f_mapping->host);
169 if (offset > 0)
170 loopsize -= offset;
171 /* offset is beyond i_size, weird but possible */
172 if (loopsize < 0)
173 return 0;
174
175 if (sizelimit > 0 && sizelimit < loopsize)
176 loopsize = sizelimit;
177 /*
178 * Unfortunately, if we want to do I/O on the device,
179 * the number of 512-byte sectors has to fit into a sector_t.
180 */
181 return loopsize >> 9;
182}
183
184static loff_t get_loop_size(struct loop_device *lo, struct file *file)
185{
186 return get_size(lo->lo_offset, lo->lo_sizelimit, file);
187}
188
189static int
190figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
191{
192 loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
193 sector_t x = (sector_t)size;
194 struct block_device *bdev = lo->lo_device;
195
196 if (unlikely((loff_t)x != size))
197 return -EFBIG;
198 if (lo->lo_offset != offset)
199 lo->lo_offset = offset;
200 if (lo->lo_sizelimit != sizelimit)
201 lo->lo_sizelimit = sizelimit;
202 set_capacity(lo->lo_disk, x);
203 bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
204 /* let user-space know about the new size */
205 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
206 return 0;
207}
208
209static inline int
210lo_do_transfer(struct loop_device *lo, int cmd,
211 struct page *rpage, unsigned roffs,
212 struct page *lpage, unsigned loffs,
213 int size, sector_t rblock)
214{
215 if (unlikely(!lo->transfer))
216 return 0;
217
218 return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
219}
220
221/**
222 * __do_lo_send_write - helper for writing data to a loop device
223 *
224 * This helper just factors out common code between do_lo_send_direct_write()
225 * and do_lo_send_write().
226 */
227static int __do_lo_send_write(struct file *file,
228 u8 *buf, const int len, loff_t pos)
229{
230 ssize_t bw;
231 mm_segment_t old_fs = get_fs();
232
233 file_start_write(file);
234 set_fs(get_ds());
235 bw = file->f_op->write(file, buf, len, &pos);
236 set_fs(old_fs);
237 file_end_write(file);
238 if (likely(bw == len))
239 return 0;
240 printk_ratelimited(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
241 (unsigned long long)pos, len);
242 if (bw >= 0)
243 bw = -EIO;
244 return bw;
245}
246
247/**
248 * do_lo_send_direct_write - helper for writing data to a loop device
249 *
250 * This is the fast, non-transforming version that does not need double
251 * buffering.
252 */
253static int do_lo_send_direct_write(struct loop_device *lo,
254 struct bio_vec *bvec, loff_t pos, struct page *page)
255{
256 ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
257 kmap(bvec->bv_page) + bvec->bv_offset,
258 bvec->bv_len, pos);
259 kunmap(bvec->bv_page);
260 cond_resched();
261 return bw;
262}
263
264/**
265 * do_lo_send_write - helper for writing data to a loop device
266 *
267 * This is the slow, transforming version that needs to double buffer the
268 * data as it cannot do the transformations in place without having direct
269 * access to the destination pages of the backing file.
270 */
271static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
272 loff_t pos, struct page *page)
273{
274 int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
275 bvec->bv_offset, bvec->bv_len, pos >> 9);
276 if (likely(!ret))
277 return __do_lo_send_write(lo->lo_backing_file,
278 page_address(page), bvec->bv_len,
279 pos);
280 printk_ratelimited(KERN_ERR "loop: Transfer error at byte offset %llu, "
281 "length %i.\n", (unsigned long long)pos, bvec->bv_len);
282 if (ret > 0)
283 ret = -EIO;
284 return ret;
285}
286
287static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos)
288{
289 int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t,
290 struct page *page);
291 struct bio_vec bvec;
292 struct bvec_iter iter;
293 struct page *page = NULL;
294 int ret = 0;
295
296 if (lo->transfer != transfer_none) {
297 page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
298 if (unlikely(!page))
299 goto fail;
300 kmap(page);
301 do_lo_send = do_lo_send_write;
302 } else {
303 do_lo_send = do_lo_send_direct_write;
304 }
305
306 bio_for_each_segment(bvec, bio, iter) {
307 ret = do_lo_send(lo, &bvec, pos, page);
308 if (ret < 0)
309 break;
310 pos += bvec.bv_len;
311 }
312 if (page) {
313 kunmap(page);
314 __free_page(page);
315 }
316out:
317 return ret;
318fail:
319 printk_ratelimited(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
320 ret = -ENOMEM;
321 goto out;
322}
323
324struct lo_read_data {
325 struct loop_device *lo;
326 struct page *page;
327 unsigned offset;
328 int bsize;
329};
330
331static int
332lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
333 struct splice_desc *sd)
334{
335 struct lo_read_data *p = sd->u.data;
336 struct loop_device *lo = p->lo;
337 struct page *page = buf->page;
338 sector_t IV;
339 int size;
340
341 IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) +
342 (buf->offset >> 9);
343 size = sd->len;
344 if (size > p->bsize)
345 size = p->bsize;
346
347 if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) {
348 printk_ratelimited(KERN_ERR "loop: transfer error block %ld\n",
349 page->index);
350 size = -EINVAL;
351 }
352
353 flush_dcache_page(p->page);
354
355 if (size > 0)
356 p->offset += size;
357
358 return size;
359}
360
361static int
362lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd)
363{
364 return __splice_from_pipe(pipe, sd, lo_splice_actor);
365}
366
367static ssize_t
368do_lo_receive(struct loop_device *lo,
369 struct bio_vec *bvec, int bsize, loff_t pos)
370{
371 struct lo_read_data cookie;
372 struct splice_desc sd;
373 struct file *file;
374 ssize_t retval;
375
376 cookie.lo = lo;
377 cookie.page = bvec->bv_page;
378 cookie.offset = bvec->bv_offset;
379 cookie.bsize = bsize;
380
381 sd.len = 0;
382 sd.total_len = bvec->bv_len;
383 sd.flags = 0;
384 sd.pos = pos;
385 sd.u.data = &cookie;
386
387 file = lo->lo_backing_file;
388 retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);
389
390 return retval;
391}
392
393static int
394lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos)
395{
396 struct bio_vec bvec;
397 struct bvec_iter iter;
398 ssize_t s;
399
400 bio_for_each_segment(bvec, bio, iter) {
401 s = do_lo_receive(lo, &bvec, bsize, pos);
402 if (s < 0)
403 return s;
404
405 if (s != bvec.bv_len) {
406 zero_fill_bio(bio);
407 break;
408 }
409 pos += bvec.bv_len;
410 }
411 return 0;
412}
413
414static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
415{
416 loff_t pos;
417 int ret;
418
419 pos = ((loff_t) bio->bi_iter.bi_sector << 9) + lo->lo_offset;
420
421 if (bio_rw(bio) == WRITE) {
422 struct file *file = lo->lo_backing_file;
423
424 if (bio->bi_rw & REQ_FLUSH) {
425 ret = vfs_fsync(file, 0);
426 if (unlikely(ret && ret != -EINVAL)) {
427 ret = -EIO;
428 goto out;
429 }
430 }
431
432 /*
433 * We use punch hole to reclaim the free space used by the
434 * image a.k.a. discard. However we do not support discard if
435 * encryption is enabled, because it may give an attacker
436 * useful information.
437 */
438 if (bio->bi_rw & REQ_DISCARD) {
439 struct file *file = lo->lo_backing_file;
440 int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
441
442 if ((!file->f_op->fallocate) ||
443 lo->lo_encrypt_key_size) {
444 ret = -EOPNOTSUPP;
445 goto out;
446 }
447 ret = file->f_op->fallocate(file, mode, pos,
448 bio->bi_iter.bi_size);
449 if (unlikely(ret && ret != -EINVAL &&
450 ret != -EOPNOTSUPP))
451 ret = -EIO;
452 goto out;
453 }
454
455 ret = lo_send(lo, bio, pos);
456
457 if ((bio->bi_rw & REQ_FUA) && !ret) {
458 ret = vfs_fsync(file, 0);
459 if (unlikely(ret && ret != -EINVAL))
460 ret = -EIO;
461 }
462 } else
463 ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
464
465out:
466 return ret;
467}
468
469/*
470 * Add bio to back of pending list
471 */
472static void loop_add_bio(struct loop_device *lo, struct bio *bio)
473{
474 lo->lo_bio_count++;
475 bio_list_add(&lo->lo_bio_list, bio);
476}
477
478/*
479 * Grab first pending buffer
480 */
481static struct bio *loop_get_bio(struct loop_device *lo)
482{
483 lo->lo_bio_count--;
484 return bio_list_pop(&lo->lo_bio_list);
485}
486
487static void loop_make_request(struct request_queue *q, struct bio *old_bio)
488{
489 struct loop_device *lo = q->queuedata;
490 int rw = bio_rw(old_bio);
491
492 if (rw == READA)
493 rw = READ;
494
495 BUG_ON(!lo || (rw != READ && rw != WRITE));
496
497 spin_lock_irq(&lo->lo_lock);
498 if (lo->lo_state != Lo_bound)
499 goto out;
500 if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))
501 goto out;
502 if (lo->lo_bio_count >= q->nr_congestion_on)
503 wait_event_lock_irq(lo->lo_req_wait,
504 lo->lo_bio_count < q->nr_congestion_off,
505 lo->lo_lock);
506 loop_add_bio(lo, old_bio);
507 wake_up(&lo->lo_event);
508 spin_unlock_irq(&lo->lo_lock);
509 return;
510
511out:
512 spin_unlock_irq(&lo->lo_lock);
513 bio_io_error(old_bio);
514}
515
516struct switch_request {
517 struct file *file;
518 struct completion wait;
519};
520
521static void do_loop_switch(struct loop_device *, struct switch_request *);
522
523static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio)
524{
525 if (unlikely(!bio->bi_bdev)) {
526 do_loop_switch(lo, bio->bi_private);
527 bio_put(bio);
528 } else {
529 int ret = do_bio_filebacked(lo, bio);
530 bio_endio(bio, ret);
531 }
532}
533
534/*
535 * worker thread that handles reads/writes to file backed loop devices,
536 * to avoid blocking in our make_request_fn. it also does loop decrypting
537 * on reads for block backed loop, as that is too heavy to do from
538 * b_end_io context where irqs may be disabled.
539 *
540 * Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before
541 * calling kthread_stop(). Therefore once kthread_should_stop() is
542 * true, make_request will not place any more requests. Therefore
543 * once kthread_should_stop() is true and lo_bio is NULL, we are
544 * done with the loop.
545 */
546static int loop_thread(void *data)
547{
548 struct loop_device *lo = data;
549 struct bio *bio;
550
551 set_user_nice(current, -20);
552
553 while (!kthread_should_stop() || !bio_list_empty(&lo->lo_bio_list)) {
554
555 wait_event_interruptible(lo->lo_event,
556 !bio_list_empty(&lo->lo_bio_list) ||
557 kthread_should_stop());
558
559 if (bio_list_empty(&lo->lo_bio_list))
560 continue;
561 spin_lock_irq(&lo->lo_lock);
562 bio = loop_get_bio(lo);
563 if (lo->lo_bio_count < lo->lo_queue->nr_congestion_off)
564 wake_up(&lo->lo_req_wait);
565 spin_unlock_irq(&lo->lo_lock);
566
567 BUG_ON(!bio);
568 loop_handle_bio(lo, bio);
569 }
570
571 return 0;
572}
573
574/*
575 * loop_switch performs the hard work of switching a backing store.
576 * First it needs to flush existing IO, it does this by sending a magic
577 * BIO down the pipe. The completion of this BIO does the actual switch.
578 */
579static int loop_switch(struct loop_device *lo, struct file *file)
580{
581 struct switch_request w;
582 struct bio *bio = bio_alloc(GFP_KERNEL, 0);
583 if (!bio)
584 return -ENOMEM;
585 init_completion(&w.wait);
586 w.file = file;
587 bio->bi_private = &w;
588 bio->bi_bdev = NULL;
589 loop_make_request(lo->lo_queue, bio);
590 wait_for_completion(&w.wait);
591 return 0;
592}
593
594/*
595 * Helper to flush the IOs in loop, but keeping loop thread running
596 */
597static int loop_flush(struct loop_device *lo)
598{
599 /* loop not yet configured, no running thread, nothing to flush */
600 if (!lo->lo_thread)
601 return 0;
602
603 return loop_switch(lo, NULL);
604}
605
606/*
607 * Do the actual switch; called from the BIO completion routine
608 */
609static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
610{
611 struct file *file = p->file;
612 struct file *old_file = lo->lo_backing_file;
613 struct address_space *mapping;
614
615 /* if no new file, only flush of queued bios requested */
616 if (!file)
617 goto out;
618
619 mapping = file->f_mapping;
620 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
621 lo->lo_backing_file = file;
622 lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
623 mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
624 lo->old_gfp_mask = mapping_gfp_mask(mapping);
625 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
626out:
627 complete(&p->wait);
628}
629
630
631/*
632 * loop_change_fd switched the backing store of a loopback device to
633 * a new file. This is useful for operating system installers to free up
634 * the original file and in High Availability environments to switch to
635 * an alternative location for the content in case of server meltdown.
636 * This can only work if the loop device is used read-only, and if the
637 * new backing store is the same size and type as the old backing store.
638 */
639static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
640 unsigned int arg)
641{
642 struct file *file, *old_file;
643 struct inode *inode;
644 int error;
645
646 error = -ENXIO;
647 if (lo->lo_state != Lo_bound)
648 goto out;
649
650 /* the loop device has to be read-only */
651 error = -EINVAL;
652 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
653 goto out;
654
655 error = -EBADF;
656 file = fget(arg);
657 if (!file)
658 goto out;
659
660 inode = file->f_mapping->host;
661 old_file = lo->lo_backing_file;
662
663 error = -EINVAL;
664
665 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
666 goto out_putf;
667
668 /* size of the new backing store needs to be the same */
669 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
670 goto out_putf;
671
672 /* and ... switch */
673 error = loop_switch(lo, file);
674 if (error)
675 goto out_putf;
676
677 fput(old_file);
678 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
679 ioctl_by_bdev(bdev, BLKRRPART, 0);
680 return 0;
681
682 out_putf:
683 fput(file);
684 out:
685 return error;
686}
687
688static inline int is_loop_device(struct file *file)
689{
690 struct inode *i = file->f_mapping->host;
691
692 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
693}
694
695/* loop sysfs attributes */
696
697static ssize_t loop_attr_show(struct device *dev, char *page,
698 ssize_t (*callback)(struct loop_device *, char *))
699{
700 struct gendisk *disk = dev_to_disk(dev);
701 struct loop_device *lo = disk->private_data;
702
703 return callback(lo, page);
704}
705
706#define LOOP_ATTR_RO(_name) \
707static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
708static ssize_t loop_attr_do_show_##_name(struct device *d, \
709 struct device_attribute *attr, char *b) \
710{ \
711 return loop_attr_show(d, b, loop_attr_##_name##_show); \
712} \
713static struct device_attribute loop_attr_##_name = \
714 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
715
716static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
717{
718 ssize_t ret;
719 char *p = NULL;
720
721 spin_lock_irq(&lo->lo_lock);
722 if (lo->lo_backing_file)
723 p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1);
724 spin_unlock_irq(&lo->lo_lock);
725
726 if (IS_ERR_OR_NULL(p))
727 ret = PTR_ERR(p);
728 else {
729 ret = strlen(p);
730 memmove(buf, p, ret);
731 buf[ret++] = '\n';
732 buf[ret] = 0;
733 }
734
735 return ret;
736}
737
738static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
739{
740 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
741}
742
743static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
744{
745 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
746}
747
748static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
749{
750 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
751
752 return sprintf(buf, "%s\n", autoclear ? "1" : "0");
753}
754
755static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
756{
757 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
758
759 return sprintf(buf, "%s\n", partscan ? "1" : "0");
760}
761
762LOOP_ATTR_RO(backing_file);
763LOOP_ATTR_RO(offset);
764LOOP_ATTR_RO(sizelimit);
765LOOP_ATTR_RO(autoclear);
766LOOP_ATTR_RO(partscan);
767
768static struct attribute *loop_attrs[] = {
769 &loop_attr_backing_file.attr,
770 &loop_attr_offset.attr,
771 &loop_attr_sizelimit.attr,
772 &loop_attr_autoclear.attr,
773 &loop_attr_partscan.attr,
774 NULL,
775};
776
777static struct attribute_group loop_attribute_group = {
778 .name = "loop",
779 .attrs= loop_attrs,
780};
781
782static int loop_sysfs_init(struct loop_device *lo)
783{
784 return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
785 &loop_attribute_group);
786}
787
788static void loop_sysfs_exit(struct loop_device *lo)
789{
790 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
791 &loop_attribute_group);
792}
793
794static void loop_config_discard(struct loop_device *lo)
795{
796 struct file *file = lo->lo_backing_file;
797 struct inode *inode = file->f_mapping->host;
798 struct request_queue *q = lo->lo_queue;
799
800 /*
801 * We use punch hole to reclaim the free space used by the
802 * image a.k.a. discard. However we do not support discard if
803 * encryption is enabled, because it may give an attacker
804 * useful information.
805 */
806 if ((!file->f_op->fallocate) ||
807 lo->lo_encrypt_key_size) {
808 q->limits.discard_granularity = 0;
809 q->limits.discard_alignment = 0;
810 q->limits.max_discard_sectors = 0;
811 q->limits.discard_zeroes_data = 0;
812 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
813 return;
814 }
815
816 q->limits.discard_granularity = inode->i_sb->s_blocksize;
817 q->limits.discard_alignment = 0;
818 q->limits.max_discard_sectors = UINT_MAX >> 9;
819 q->limits.discard_zeroes_data = 1;
820 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
821}
822
823static int loop_set_fd(struct loop_device *lo, fmode_t mode,
824 struct block_device *bdev, unsigned int arg)
825{
826 struct file *file, *f;
827 struct inode *inode;
828 struct address_space *mapping;
829 unsigned lo_blocksize;
830 int lo_flags = 0;
831 int error;
832 loff_t size;
833
834 /* This is safe, since we have a reference from open(). */
835 __module_get(THIS_MODULE);
836
837 error = -EBADF;
838 file = fget(arg);
839 if (!file)
840 goto out;
841
842 error = -EBUSY;
843 if (lo->lo_state != Lo_unbound)
844 goto out_putf;
845
846 /* Avoid recursion */
847 f = file;
848 while (is_loop_device(f)) {
849 struct loop_device *l;
850
851 if (f->f_mapping->host->i_bdev == bdev)
852 goto out_putf;
853
854 l = f->f_mapping->host->i_bdev->bd_disk->private_data;
855 if (l->lo_state == Lo_unbound) {
856 error = -EINVAL;
857 goto out_putf;
858 }
859 f = l->lo_backing_file;
860 }
861
862 mapping = file->f_mapping;
863 inode = mapping->host;
864
865 error = -EINVAL;
866 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
867 goto out_putf;
868
869 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
870 !file->f_op->write)
871 lo_flags |= LO_FLAGS_READ_ONLY;
872
873 lo_blocksize = S_ISBLK(inode->i_mode) ?
874 inode->i_bdev->bd_block_size : PAGE_SIZE;
875
876 error = -EFBIG;
877 size = get_loop_size(lo, file);
878 if ((loff_t)(sector_t)size != size)
879 goto out_putf;
880
881 error = 0;
882
883 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
884
885 lo->lo_blocksize = lo_blocksize;
886 lo->lo_device = bdev;
887 lo->lo_flags = lo_flags;
888 lo->lo_backing_file = file;
889 lo->transfer = transfer_none;
890 lo->ioctl = NULL;
891 lo->lo_sizelimit = 0;
892 lo->lo_bio_count = 0;
893 lo->old_gfp_mask = mapping_gfp_mask(mapping);
894 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
895
896 bio_list_init(&lo->lo_bio_list);
897
898 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
899 blk_queue_flush(lo->lo_queue, REQ_FLUSH);
900
901 set_capacity(lo->lo_disk, size);
902 bd_set_size(bdev, size << 9);
903 loop_sysfs_init(lo);
904 /* let user-space know about the new size */
905 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
906
907 set_blocksize(bdev, lo_blocksize);
908
909 lo->lo_thread = kthread_create(loop_thread, lo, "loop%d",
910 lo->lo_number);
911 if (IS_ERR(lo->lo_thread)) {
912 error = PTR_ERR(lo->lo_thread);
913 goto out_clr;
914 }
915 lo->lo_state = Lo_bound;
916 wake_up_process(lo->lo_thread);
917 if (part_shift)
918 lo->lo_flags |= LO_FLAGS_PARTSCAN;
919 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
920 ioctl_by_bdev(bdev, BLKRRPART, 0);
921
922 /* Grab the block_device to prevent its destruction after we
923 * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev).
924 */
925 bdgrab(bdev);
926 return 0;
927
928out_clr:
929 loop_sysfs_exit(lo);
930 lo->lo_thread = NULL;
931 lo->lo_device = NULL;
932 lo->lo_backing_file = NULL;
933 lo->lo_flags = 0;
934 set_capacity(lo->lo_disk, 0);
935 invalidate_bdev(bdev);
936 bd_set_size(bdev, 0);
937 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
938 mapping_set_gfp_mask(mapping, lo->old_gfp_mask);
939 lo->lo_state = Lo_unbound;
940 out_putf:
941 fput(file);
942 out:
943 /* This is safe: open() is still holding a reference. */
944 module_put(THIS_MODULE);
945 return error;
946}
947
948static int
949loop_release_xfer(struct loop_device *lo)
950{
951 int err = 0;
952 struct loop_func_table *xfer = lo->lo_encryption;
953
954 if (xfer) {
955 if (xfer->release)
956 err = xfer->release(lo);
957 lo->transfer = NULL;
958 lo->lo_encryption = NULL;
959 module_put(xfer->owner);
960 }
961 return err;
962}
963
964static int
965loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
966 const struct loop_info64 *i)
967{
968 int err = 0;
969
970 if (xfer) {
971 struct module *owner = xfer->owner;
972
973 if (!try_module_get(owner))
974 return -EINVAL;
975 if (xfer->init)
976 err = xfer->init(lo, i);
977 if (err)
978 module_put(owner);
979 else
980 lo->lo_encryption = xfer;
981 }
982 return err;
983}
984
985static int loop_clr_fd(struct loop_device *lo)
986{
987 struct file *filp = lo->lo_backing_file;
988 gfp_t gfp = lo->old_gfp_mask;
989 struct block_device *bdev = lo->lo_device;
990
991 if (lo->lo_state != Lo_bound)
992 return -ENXIO;
993
994 /*
995 * If we've explicitly asked to tear down the loop device,
996 * and it has an elevated reference count, set it for auto-teardown when
997 * the last reference goes away. This stops $!~#$@ udev from
998 * preventing teardown because it decided that it needs to run blkid on
999 * the loopback device whenever they appear. xfstests is notorious for
1000 * failing tests because blkid via udev races with a losetup
1001 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
1002 * command to fail with EBUSY.
1003 */
1004 if (lo->lo_refcnt > 1) {
1005 lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
1006 mutex_unlock(&lo->lo_ctl_mutex);
1007 return 0;
1008 }
1009
1010 if (filp == NULL)
1011 return -EINVAL;
1012
1013 spin_lock_irq(&lo->lo_lock);
1014 lo->lo_state = Lo_rundown;
1015 spin_unlock_irq(&lo->lo_lock);
1016
1017 kthread_stop(lo->lo_thread);
1018
1019 spin_lock_irq(&lo->lo_lock);
1020 lo->lo_backing_file = NULL;
1021 spin_unlock_irq(&lo->lo_lock);
1022
1023 loop_release_xfer(lo);
1024 lo->transfer = NULL;
1025 lo->ioctl = NULL;
1026 lo->lo_device = NULL;
1027 lo->lo_encryption = NULL;
1028 lo->lo_offset = 0;
1029 lo->lo_sizelimit = 0;
1030 lo->lo_encrypt_key_size = 0;
1031 lo->lo_thread = NULL;
1032 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
1033 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
1034 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1035 if (bdev) {
1036 bdput(bdev);
1037 invalidate_bdev(bdev);
1038 }
1039 set_capacity(lo->lo_disk, 0);
1040 loop_sysfs_exit(lo);
1041 if (bdev) {
1042 bd_set_size(bdev, 0);
1043 /* let user-space know about this change */
1044 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1045 }
1046 mapping_set_gfp_mask(filp->f_mapping, gfp);
1047 lo->lo_state = Lo_unbound;
1048 /* This is safe: open() is still holding a reference. */
1049 module_put(THIS_MODULE);
1050 if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
1051 ioctl_by_bdev(bdev, BLKRRPART, 0);
1052 lo->lo_flags = 0;
1053 if (!part_shift)
1054 lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
1055 mutex_unlock(&lo->lo_ctl_mutex);
1056 /*
1057 * Need not hold lo_ctl_mutex to fput backing file.
1058 * Calling fput holding lo_ctl_mutex triggers a circular
1059 * lock dependency possibility warning as fput can take
1060 * bd_mutex which is usually taken before lo_ctl_mutex.
1061 */
1062 fput(filp);
1063 return 0;
1064}
1065
1066static int
1067loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1068{
1069 int err;
1070 struct loop_func_table *xfer;
1071 kuid_t uid = current_uid();
1072
1073 if (lo->lo_encrypt_key_size &&
1074 !uid_eq(lo->lo_key_owner, uid) &&
1075 !capable(CAP_SYS_ADMIN))
1076 return -EPERM;
1077 if (lo->lo_state != Lo_bound)
1078 return -ENXIO;
1079 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
1080 return -EINVAL;
1081
1082 err = loop_release_xfer(lo);
1083 if (err)
1084 return err;
1085
1086 if (info->lo_encrypt_type) {
1087 unsigned int type = info->lo_encrypt_type;
1088
1089 if (type >= MAX_LO_CRYPT)
1090 return -EINVAL;
1091 xfer = xfer_funcs[type];
1092 if (xfer == NULL)
1093 return -EINVAL;
1094 } else
1095 xfer = NULL;
1096
1097 err = loop_init_xfer(lo, xfer, info);
1098 if (err)
1099 return err;
1100
1101 if (lo->lo_offset != info->lo_offset ||
1102 lo->lo_sizelimit != info->lo_sizelimit)
1103 if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
1104 return -EFBIG;
1105
1106 loop_config_discard(lo);
1107
1108 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
1109 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
1110 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
1111 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
1112
1113 if (!xfer)
1114 xfer = &none_funcs;
1115 lo->transfer = xfer->transfer;
1116 lo->ioctl = xfer->ioctl;
1117
1118 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
1119 (info->lo_flags & LO_FLAGS_AUTOCLEAR))
1120 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
1121
1122 if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&
1123 !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
1124 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1125 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
1126 ioctl_by_bdev(lo->lo_device, BLKRRPART, 0);
1127 }
1128
1129 lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
1130 lo->lo_init[0] = info->lo_init[0];
1131 lo->lo_init[1] = info->lo_init[1];
1132 if (info->lo_encrypt_key_size) {
1133 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
1134 info->lo_encrypt_key_size);
1135 lo->lo_key_owner = uid;
1136 }
1137
1138 return 0;
1139}
1140
1141static int
1142loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1143{
1144 struct file *file = lo->lo_backing_file;
1145 struct kstat stat;
1146 int error;
1147
1148 if (lo->lo_state != Lo_bound)
1149 return -ENXIO;
1150 error = vfs_getattr(&file->f_path, &stat);
1151 if (error)
1152 return error;
1153 memset(info, 0, sizeof(*info));
1154 info->lo_number = lo->lo_number;
1155 info->lo_device = huge_encode_dev(stat.dev);
1156 info->lo_inode = stat.ino;
1157 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
1158 info->lo_offset = lo->lo_offset;
1159 info->lo_sizelimit = lo->lo_sizelimit;
1160 info->lo_flags = lo->lo_flags;
1161 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1162 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1163 info->lo_encrypt_type =
1164 lo->lo_encryption ? lo->lo_encryption->number : 0;
1165 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1166 info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1167 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1168 lo->lo_encrypt_key_size);
1169 }
1170 return 0;
1171}
1172
1173static void
1174loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1175{
1176 memset(info64, 0, sizeof(*info64));
1177 info64->lo_number = info->lo_number;
1178 info64->lo_device = info->lo_device;
1179 info64->lo_inode = info->lo_inode;
1180 info64->lo_rdevice = info->lo_rdevice;
1181 info64->lo_offset = info->lo_offset;
1182 info64->lo_sizelimit = 0;
1183 info64->lo_encrypt_type = info->lo_encrypt_type;
1184 info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1185 info64->lo_flags = info->lo_flags;
1186 info64->lo_init[0] = info->lo_init[0];
1187 info64->lo_init[1] = info->lo_init[1];
1188 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1189 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1190 else
1191 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1192 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1193}
1194
1195static int
1196loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1197{
1198 memset(info, 0, sizeof(*info));
1199 info->lo_number = info64->lo_number;
1200 info->lo_device = info64->lo_device;
1201 info->lo_inode = info64->lo_inode;
1202 info->lo_rdevice = info64->lo_rdevice;
1203 info->lo_offset = info64->lo_offset;
1204 info->lo_encrypt_type = info64->lo_encrypt_type;
1205 info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1206 info->lo_flags = info64->lo_flags;
1207 info->lo_init[0] = info64->lo_init[0];
1208 info->lo_init[1] = info64->lo_init[1];
1209 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1210 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1211 else
1212 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1213 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1214
1215 /* error in case values were truncated */
1216 if (info->lo_device != info64->lo_device ||
1217 info->lo_rdevice != info64->lo_rdevice ||
1218 info->lo_inode != info64->lo_inode ||
1219 info->lo_offset != info64->lo_offset)
1220 return -EOVERFLOW;
1221
1222 return 0;
1223}
1224
1225static int
1226loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1227{
1228 struct loop_info info;
1229 struct loop_info64 info64;
1230
1231 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1232 return -EFAULT;
1233 loop_info64_from_old(&info, &info64);
1234 return loop_set_status(lo, &info64);
1235}
1236
1237static int
1238loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1239{
1240 struct loop_info64 info64;
1241
1242 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1243 return -EFAULT;
1244 return loop_set_status(lo, &info64);
1245}
1246
1247static int
1248loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1249 struct loop_info info;
1250 struct loop_info64 info64;
1251 int err = 0;
1252
1253 if (!arg)
1254 err = -EINVAL;
1255 if (!err)
1256 err = loop_get_status(lo, &info64);
1257 if (!err)
1258 err = loop_info64_to_old(&info64, &info);
1259 if (!err && copy_to_user(arg, &info, sizeof(info)))
1260 err = -EFAULT;
1261
1262 return err;
1263}
1264
1265static int
1266loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1267 struct loop_info64 info64;
1268 int err = 0;
1269
1270 if (!arg)
1271 err = -EINVAL;
1272 if (!err)
1273 err = loop_get_status(lo, &info64);
1274 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1275 err = -EFAULT;
1276
1277 return err;
1278}
1279
1280static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
1281{
1282 if (unlikely(lo->lo_state != Lo_bound))
1283 return -ENXIO;
1284
1285 return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
1286}
1287
1288static int lo_ioctl(struct block_device *bdev, fmode_t mode,
1289 unsigned int cmd, unsigned long arg)
1290{
1291 struct loop_device *lo = bdev->bd_disk->private_data;
1292 int err;
1293
1294 mutex_lock_nested(&lo->lo_ctl_mutex, 1);
1295 switch (cmd) {
1296 case LOOP_SET_FD:
1297 err = loop_set_fd(lo, mode, bdev, arg);
1298 break;
1299 case LOOP_CHANGE_FD:
1300 err = loop_change_fd(lo, bdev, arg);
1301 break;
1302 case LOOP_CLR_FD:
1303 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1304 err = loop_clr_fd(lo);
1305 if (!err)
1306 goto out_unlocked;
1307 break;
1308 case LOOP_SET_STATUS:
1309 err = -EPERM;
1310 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1311 err = loop_set_status_old(lo,
1312 (struct loop_info __user *)arg);
1313 break;
1314 case LOOP_GET_STATUS:
1315 err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1316 break;
1317 case LOOP_SET_STATUS64:
1318 err = -EPERM;
1319 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1320 err = loop_set_status64(lo,
1321 (struct loop_info64 __user *) arg);
1322 break;
1323 case LOOP_GET_STATUS64:
1324 err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1325 break;
1326 case LOOP_SET_CAPACITY:
1327 err = -EPERM;
1328 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1329 err = loop_set_capacity(lo, bdev);
1330 break;
1331 default:
1332 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1333 }
1334 mutex_unlock(&lo->lo_ctl_mutex);
1335
1336out_unlocked:
1337 return err;
1338}
1339
1340#ifdef CONFIG_COMPAT
1341struct compat_loop_info {
1342 compat_int_t lo_number; /* ioctl r/o */
1343 compat_dev_t lo_device; /* ioctl r/o */
1344 compat_ulong_t lo_inode; /* ioctl r/o */
1345 compat_dev_t lo_rdevice; /* ioctl r/o */
1346 compat_int_t lo_offset;
1347 compat_int_t lo_encrypt_type;
1348 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1349 compat_int_t lo_flags; /* ioctl r/o */
1350 char lo_name[LO_NAME_SIZE];
1351 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1352 compat_ulong_t lo_init[2];
1353 char reserved[4];
1354};
1355
1356/*
1357 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1358 * - noinlined to reduce stack space usage in main part of driver
1359 */
1360static noinline int
1361loop_info64_from_compat(const struct compat_loop_info __user *arg,
1362 struct loop_info64 *info64)
1363{
1364 struct compat_loop_info info;
1365
1366 if (copy_from_user(&info, arg, sizeof(info)))
1367 return -EFAULT;
1368
1369 memset(info64, 0, sizeof(*info64));
1370 info64->lo_number = info.lo_number;
1371 info64->lo_device = info.lo_device;
1372 info64->lo_inode = info.lo_inode;
1373 info64->lo_rdevice = info.lo_rdevice;
1374 info64->lo_offset = info.lo_offset;
1375 info64->lo_sizelimit = 0;
1376 info64->lo_encrypt_type = info.lo_encrypt_type;
1377 info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1378 info64->lo_flags = info.lo_flags;
1379 info64->lo_init[0] = info.lo_init[0];
1380 info64->lo_init[1] = info.lo_init[1];
1381 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1382 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1383 else
1384 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1385 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1386 return 0;
1387}
1388
1389/*
1390 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1391 * - noinlined to reduce stack space usage in main part of driver
1392 */
1393static noinline int
1394loop_info64_to_compat(const struct loop_info64 *info64,
1395 struct compat_loop_info __user *arg)
1396{
1397 struct compat_loop_info info;
1398
1399 memset(&info, 0, sizeof(info));
1400 info.lo_number = info64->lo_number;
1401 info.lo_device = info64->lo_device;
1402 info.lo_inode = info64->lo_inode;
1403 info.lo_rdevice = info64->lo_rdevice;
1404 info.lo_offset = info64->lo_offset;
1405 info.lo_encrypt_type = info64->lo_encrypt_type;
1406 info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
1407 info.lo_flags = info64->lo_flags;
1408 info.lo_init[0] = info64->lo_init[0];
1409 info.lo_init[1] = info64->lo_init[1];
1410 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1411 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1412 else
1413 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1414 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1415
1416 /* error in case values were truncated */
1417 if (info.lo_device != info64->lo_device ||
1418 info.lo_rdevice != info64->lo_rdevice ||
1419 info.lo_inode != info64->lo_inode ||
1420 info.lo_offset != info64->lo_offset ||
1421 info.lo_init[0] != info64->lo_init[0] ||
1422 info.lo_init[1] != info64->lo_init[1])
1423 return -EOVERFLOW;
1424
1425 if (copy_to_user(arg, &info, sizeof(info)))
1426 return -EFAULT;
1427 return 0;
1428}
1429
1430static int
1431loop_set_status_compat(struct loop_device *lo,
1432 const struct compat_loop_info __user *arg)
1433{
1434 struct loop_info64 info64;
1435 int ret;
1436
1437 ret = loop_info64_from_compat(arg, &info64);
1438 if (ret < 0)
1439 return ret;
1440 return loop_set_status(lo, &info64);
1441}
1442
1443static int
1444loop_get_status_compat(struct loop_device *lo,
1445 struct compat_loop_info __user *arg)
1446{
1447 struct loop_info64 info64;
1448 int err = 0;
1449
1450 if (!arg)
1451 err = -EINVAL;
1452 if (!err)
1453 err = loop_get_status(lo, &info64);
1454 if (!err)
1455 err = loop_info64_to_compat(&info64, arg);
1456 return err;
1457}
1458
1459static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1460 unsigned int cmd, unsigned long arg)
1461{
1462 struct loop_device *lo = bdev->bd_disk->private_data;
1463 int err;
1464
1465 switch(cmd) {
1466 case LOOP_SET_STATUS:
1467 mutex_lock(&lo->lo_ctl_mutex);
1468 err = loop_set_status_compat(
1469 lo, (const struct compat_loop_info __user *) arg);
1470 mutex_unlock(&lo->lo_ctl_mutex);
1471 break;
1472 case LOOP_GET_STATUS:
1473 mutex_lock(&lo->lo_ctl_mutex);
1474 err = loop_get_status_compat(
1475 lo, (struct compat_loop_info __user *) arg);
1476 mutex_unlock(&lo->lo_ctl_mutex);
1477 break;
1478 case LOOP_SET_CAPACITY:
1479 case LOOP_CLR_FD:
1480 case LOOP_GET_STATUS64:
1481 case LOOP_SET_STATUS64:
1482 arg = (unsigned long) compat_ptr(arg);
1483 case LOOP_SET_FD:
1484 case LOOP_CHANGE_FD:
1485 err = lo_ioctl(bdev, mode, cmd, arg);
1486 break;
1487 default:
1488 err = -ENOIOCTLCMD;
1489 break;
1490 }
1491 return err;
1492}
1493#endif
1494
1495static int lo_open(struct block_device *bdev, fmode_t mode)
1496{
1497 struct loop_device *lo;
1498 int err = 0;
1499
1500 mutex_lock(&loop_index_mutex);
1501 lo = bdev->bd_disk->private_data;
1502 if (!lo) {
1503 err = -ENXIO;
1504 goto out;
1505 }
1506
1507 mutex_lock(&lo->lo_ctl_mutex);
1508 lo->lo_refcnt++;
1509 mutex_unlock(&lo->lo_ctl_mutex);
1510out:
1511 mutex_unlock(&loop_index_mutex);
1512 return err;
1513}
1514
1515static void lo_release(struct gendisk *disk, fmode_t mode)
1516{
1517 struct loop_device *lo = disk->private_data;
1518 int err;
1519
1520 mutex_lock(&lo->lo_ctl_mutex);
1521
1522 if (--lo->lo_refcnt)
1523 goto out;
1524
1525 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
1526 /*
1527 * In autoclear mode, stop the loop thread
1528 * and remove configuration after last close.
1529 */
1530 err = loop_clr_fd(lo);
1531 if (!err)
1532 return;
1533 } else {
1534 /*
1535 * Otherwise keep thread (if running) and config,
1536 * but flush possible ongoing bios in thread.
1537 */
1538 loop_flush(lo);
1539 }
1540
1541out:
1542 mutex_unlock(&lo->lo_ctl_mutex);
1543}
1544
1545static const struct block_device_operations lo_fops = {
1546 .owner = THIS_MODULE,
1547 .open = lo_open,
1548 .release = lo_release,
1549 .ioctl = lo_ioctl,
1550#ifdef CONFIG_COMPAT
1551 .compat_ioctl = lo_compat_ioctl,
1552#endif
1553};
1554
1555/*
1556 * And now the modules code and kernel interface.
1557 */
1558static int max_loop;
1559module_param(max_loop, int, S_IRUGO);
1560MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1561module_param(max_part, int, S_IRUGO);
1562MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1563MODULE_LICENSE("GPL");
1564MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1565
1566int loop_register_transfer(struct loop_func_table *funcs)
1567{
1568 unsigned int n = funcs->number;
1569
1570 if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1571 return -EINVAL;
1572 xfer_funcs[n] = funcs;
1573 return 0;
1574}
1575
1576static int unregister_transfer_cb(int id, void *ptr, void *data)
1577{
1578 struct loop_device *lo = ptr;
1579 struct loop_func_table *xfer = data;
1580
1581 mutex_lock(&lo->lo_ctl_mutex);
1582 if (lo->lo_encryption == xfer)
1583 loop_release_xfer(lo);
1584 mutex_unlock(&lo->lo_ctl_mutex);
1585 return 0;
1586}
1587
1588int loop_unregister_transfer(int number)
1589{
1590 unsigned int n = number;
1591 struct loop_func_table *xfer;
1592
1593 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1594 return -EINVAL;
1595
1596 xfer_funcs[n] = NULL;
1597 idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
1598 return 0;
1599}
1600
1601EXPORT_SYMBOL(loop_register_transfer);
1602EXPORT_SYMBOL(loop_unregister_transfer);
1603
1604static int loop_add(struct loop_device **l, int i)
1605{
1606 struct loop_device *lo;
1607 struct gendisk *disk;
1608 int err;
1609
1610 err = -ENOMEM;
1611 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1612 if (!lo)
1613 goto out;
1614
1615 lo->lo_state = Lo_unbound;
1616
1617 /* allocate id, if @id >= 0, we're requesting that specific id */
1618 if (i >= 0) {
1619 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
1620 if (err == -ENOSPC)
1621 err = -EEXIST;
1622 } else {
1623 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
1624 }
1625 if (err < 0)
1626 goto out_free_dev;
1627 i = err;
1628
1629 err = -ENOMEM;
1630 lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
1631 if (!lo->lo_queue)
1632 goto out_free_idr;
1633
1634 /*
1635 * set queue make_request_fn
1636 */
1637 blk_queue_make_request(lo->lo_queue, loop_make_request);
1638 lo->lo_queue->queuedata = lo;
1639
1640 disk = lo->lo_disk = alloc_disk(1 << part_shift);
1641 if (!disk)
1642 goto out_free_queue;
1643
1644 /*
1645 * Disable partition scanning by default. The in-kernel partition
1646 * scanning can be requested individually per-device during its
1647 * setup. Userspace can always add and remove partitions from all
1648 * devices. The needed partition minors are allocated from the
1649 * extended minor space, the main loop device numbers will continue
1650 * to match the loop minors, regardless of the number of partitions
1651 * used.
1652 *
1653 * If max_part is given, partition scanning is globally enabled for
1654 * all loop devices. The minors for the main loop devices will be
1655 * multiples of max_part.
1656 *
1657 * Note: Global-for-all-devices, set-only-at-init, read-only module
1658 * parameteters like 'max_loop' and 'max_part' make things needlessly
1659 * complicated, are too static, inflexible and may surprise
1660 * userspace tools. Parameters like this in general should be avoided.
1661 */
1662 if (!part_shift)
1663 disk->flags |= GENHD_FL_NO_PART_SCAN;
1664 disk->flags |= GENHD_FL_EXT_DEVT;
1665 mutex_init(&lo->lo_ctl_mutex);
1666 lo->lo_number = i;
1667 lo->lo_thread = NULL;
1668 init_waitqueue_head(&lo->lo_event);
1669 init_waitqueue_head(&lo->lo_req_wait);
1670 spin_lock_init(&lo->lo_lock);
1671 disk->major = LOOP_MAJOR;
1672 disk->first_minor = i << part_shift;
1673 disk->fops = &lo_fops;
1674 disk->private_data = lo;
1675 disk->queue = lo->lo_queue;
1676 sprintf(disk->disk_name, "loop%d", i);
1677 add_disk(disk);
1678 *l = lo;
1679 return lo->lo_number;
1680
1681out_free_queue:
1682 blk_cleanup_queue(lo->lo_queue);
1683out_free_idr:
1684 idr_remove(&loop_index_idr, i);
1685out_free_dev:
1686 kfree(lo);
1687out:
1688 return err;
1689}
1690
1691static void loop_remove(struct loop_device *lo)
1692{
1693 del_gendisk(lo->lo_disk);
1694 blk_cleanup_queue(lo->lo_queue);
1695 put_disk(lo->lo_disk);
1696 kfree(lo);
1697}
1698
1699static int find_free_cb(int id, void *ptr, void *data)
1700{
1701 struct loop_device *lo = ptr;
1702 struct loop_device **l = data;
1703
1704 if (lo->lo_state == Lo_unbound) {
1705 *l = lo;
1706 return 1;
1707 }
1708 return 0;
1709}
1710
1711static int loop_lookup(struct loop_device **l, int i)
1712{
1713 struct loop_device *lo;
1714 int ret = -ENODEV;
1715
1716 if (i < 0) {
1717 int err;
1718
1719 err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
1720 if (err == 1) {
1721 *l = lo;
1722 ret = lo->lo_number;
1723 }
1724 goto out;
1725 }
1726
1727 /* lookup and return a specific i */
1728 lo = idr_find(&loop_index_idr, i);
1729 if (lo) {
1730 *l = lo;
1731 ret = lo->lo_number;
1732 }
1733out:
1734 return ret;
1735}
1736
1737static struct kobject *loop_probe(dev_t dev, int *part, void *data)
1738{
1739 struct loop_device *lo;
1740 struct kobject *kobj;
1741 int err;
1742
1743 mutex_lock(&loop_index_mutex);
1744 err = loop_lookup(&lo, MINOR(dev) >> part_shift);
1745 if (err < 0)
1746 err = loop_add(&lo, MINOR(dev) >> part_shift);
1747 if (err < 0)
1748 kobj = NULL;
1749 else
1750 kobj = get_disk(lo->lo_disk);
1751 mutex_unlock(&loop_index_mutex);
1752
1753 *part = 0;
1754 return kobj;
1755}
1756
1757static long loop_control_ioctl(struct file *file, unsigned int cmd,
1758 unsigned long parm)
1759{
1760 struct loop_device *lo;
1761 int ret = -ENOSYS;
1762
1763 mutex_lock(&loop_index_mutex);
1764 switch (cmd) {
1765 case LOOP_CTL_ADD:
1766 ret = loop_lookup(&lo, parm);
1767 if (ret >= 0) {
1768 ret = -EEXIST;
1769 break;
1770 }
1771 ret = loop_add(&lo, parm);
1772 break;
1773 case LOOP_CTL_REMOVE:
1774 ret = loop_lookup(&lo, parm);
1775 if (ret < 0)
1776 break;
1777 mutex_lock(&lo->lo_ctl_mutex);
1778 if (lo->lo_state != Lo_unbound) {
1779 ret = -EBUSY;
1780 mutex_unlock(&lo->lo_ctl_mutex);
1781 break;
1782 }
1783 if (lo->lo_refcnt > 0) {
1784 ret = -EBUSY;
1785 mutex_unlock(&lo->lo_ctl_mutex);
1786 break;
1787 }
1788 lo->lo_disk->private_data = NULL;
1789 mutex_unlock(&lo->lo_ctl_mutex);
1790 idr_remove(&loop_index_idr, lo->lo_number);
1791 loop_remove(lo);
1792 break;
1793 case LOOP_CTL_GET_FREE:
1794 ret = loop_lookup(&lo, -1);
1795 if (ret >= 0)
1796 break;
1797 ret = loop_add(&lo, -1);
1798 }
1799 mutex_unlock(&loop_index_mutex);
1800
1801 return ret;
1802}
1803
1804static const struct file_operations loop_ctl_fops = {
1805 .open = nonseekable_open,
1806 .unlocked_ioctl = loop_control_ioctl,
1807 .compat_ioctl = loop_control_ioctl,
1808 .owner = THIS_MODULE,
1809 .llseek = noop_llseek,
1810};
1811
1812static struct miscdevice loop_misc = {
1813 .minor = LOOP_CTRL_MINOR,
1814 .name = "loop-control",
1815 .fops = &loop_ctl_fops,
1816};
1817
1818MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
1819MODULE_ALIAS("devname:loop-control");
1820
1821static int __init loop_init(void)
1822{
1823 int i, nr;
1824 unsigned long range;
1825 struct loop_device *lo;
1826 int err;
1827
1828 err = misc_register(&loop_misc);
1829 if (err < 0)
1830 return err;
1831
1832 part_shift = 0;
1833 if (max_part > 0) {
1834 part_shift = fls(max_part);
1835
1836 /*
1837 * Adjust max_part according to part_shift as it is exported
1838 * to user space so that user can decide correct minor number
1839 * if [s]he want to create more devices.
1840 *
1841 * Note that -1 is required because partition 0 is reserved
1842 * for the whole disk.
1843 */
1844 max_part = (1UL << part_shift) - 1;
1845 }
1846
1847 if ((1UL << part_shift) > DISK_MAX_PARTS) {
1848 err = -EINVAL;
1849 goto misc_out;
1850 }
1851
1852 if (max_loop > 1UL << (MINORBITS - part_shift)) {
1853 err = -EINVAL;
1854 goto misc_out;
1855 }
1856
1857 /*
1858 * If max_loop is specified, create that many devices upfront.
1859 * This also becomes a hard limit. If max_loop is not specified,
1860 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1861 * init time. Loop devices can be requested on-demand with the
1862 * /dev/loop-control interface, or be instantiated by accessing
1863 * a 'dead' device node.
1864 */
1865 if (max_loop) {
1866 nr = max_loop;
1867 range = max_loop << part_shift;
1868 } else {
1869 nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1870 range = 1UL << MINORBITS;
1871 }
1872
1873 if (register_blkdev(LOOP_MAJOR, "loop")) {
1874 err = -EIO;
1875 goto misc_out;
1876 }
1877
1878 blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
1879 THIS_MODULE, loop_probe, NULL, NULL);
1880
1881 /* pre-create number of devices given by config or max_loop */
1882 mutex_lock(&loop_index_mutex);
1883 for (i = 0; i < nr; i++)
1884 loop_add(&lo, i);
1885 mutex_unlock(&loop_index_mutex);
1886
1887 printk(KERN_INFO "loop: module loaded\n");
1888 return 0;
1889
1890misc_out:
1891 misc_deregister(&loop_misc);
1892 return err;
1893}
1894
1895static int loop_exit_cb(int id, void *ptr, void *data)
1896{
1897 struct loop_device *lo = ptr;
1898
1899 loop_remove(lo);
1900 return 0;
1901}
1902
1903static void __exit loop_exit(void)
1904{
1905 unsigned long range;
1906
1907 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
1908
1909 idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
1910 idr_destroy(&loop_index_idr);
1911
1912 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
1913 unregister_blkdev(LOOP_MAJOR, "loop");
1914
1915 misc_deregister(&loop_misc);
1916}
1917
1918module_init(loop_init);
1919module_exit(loop_exit);
1920
1921#ifndef MODULE
1922static int __init max_loop_setup(char *str)
1923{
1924 max_loop = simple_strtol(str, NULL, 0);
1925 return 1;
1926}
1927
1928__setup("max_loop=", max_loop_setup);
1929#endif