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drm/tests: hdmi: Fix memory leaks in drm_display_mode_from_cea_vic()
[drm/drm-misc.git] / drivers / block / loop.c
blob78a7bb28defe4cb6e41019cdda07ef88701eb345
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 */
41 enum {
42 Lo_unbound,
43 Lo_bound,
44 Lo_rundown,
45 Lo_deleting,
46 };
47
48 struct loop_func_table;
49
50 struct 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
81 struct 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
95 static DEFINE_IDR(loop_index_idr);
96 static DEFINE_MUTEX(loop_ctl_mutex);
97 static 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 */
111 static 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 */
132 static 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
139 static int max_part;
140 static int part_shift;
141
142 static 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
163 static 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 */
173 static 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
185 static void __loop_update_dio(struct loop_device *lo, bool dio)
186 {
187 struct file *file = lo->lo_backing_file;
188 struct inode *inode = file->f_mapping->host;
189 struct block_device *backing_bdev = NULL;
190 bool use_dio;
191
192 if (S_ISBLK(inode->i_mode))
193 backing_bdev = I_BDEV(inode);
194 else if (inode->i_sb->s_bdev)
195 backing_bdev = inode->i_sb->s_bdev;
196
197 use_dio = dio && (file->f_mode & FMODE_CAN_ODIRECT) &&
198 (!backing_bdev || lo_bdev_can_use_dio(lo, backing_bdev));
199
200 if (lo->use_dio == use_dio)
201 return;
202
203 /* flush dirty pages before changing direct IO */
204 vfs_fsync(file, 0);
205
206 /*
207 * The flag of LO_FLAGS_DIRECT_IO is handled similarly with
208 * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup
209 * will get updated by ioctl(LOOP_GET_STATUS)
210 */
211 if (lo->lo_state == Lo_bound)
212 blk_mq_freeze_queue(lo->lo_queue);
213 lo->use_dio = use_dio;
214 if (use_dio)
215 lo->lo_flags |= LO_FLAGS_DIRECT_IO;
216 else
217 lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
218 if (lo->lo_state == Lo_bound)
219 blk_mq_unfreeze_queue(lo->lo_queue);
220 }
221
222 /**
223 * loop_set_size() - sets device size and notifies userspace
224 * @lo: struct loop_device to set the size for
225 * @size: new size of the loop device
226 *
227 * Callers must validate that the size passed into this function fits into
228 * a sector_t, eg using loop_validate_size()
229 */
230 static void loop_set_size(struct loop_device *lo, loff_t size)
231 {
232 if (!set_capacity_and_notify(lo->lo_disk, size))
233 kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
234 }
235
236 static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)
237 {
238 struct iov_iter i;
239 ssize_t bw;
240
241 iov_iter_bvec(&i, ITER_SOURCE, bvec, 1, bvec->bv_len);
242
243 bw = vfs_iter_write(file, &i, ppos, 0);
244
245 if (likely(bw == bvec->bv_len))
246 return 0;
247
248 printk_ratelimited(KERN_ERR
249 "loop: Write error at byte offset %llu, length %i.\n",
250 (unsigned long long)*ppos, bvec->bv_len);
251 if (bw >= 0)
252 bw = -EIO;
253 return bw;
254 }
255
256 static int lo_write_simple(struct loop_device *lo, struct request *rq,
257 loff_t pos)
258 {
259 struct bio_vec bvec;
260 struct req_iterator iter;
261 int ret = 0;
262
263 rq_for_each_segment(bvec, rq, iter) {
264 ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
265 if (ret < 0)
266 break;
267 cond_resched();
268 }
269
270 return ret;
271 }
272
273 static int lo_read_simple(struct loop_device *lo, struct request *rq,
274 loff_t pos)
275 {
276 struct bio_vec bvec;
277 struct req_iterator iter;
278 struct iov_iter i;
279 ssize_t len;
280
281 rq_for_each_segment(bvec, rq, iter) {
282 iov_iter_bvec(&i, ITER_DEST, &bvec, 1, bvec.bv_len);
283 len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);
284 if (len < 0)
285 return len;
286
287 flush_dcache_page(bvec.bv_page);
288
289 if (len != bvec.bv_len) {
290 struct bio *bio;
291
292 __rq_for_each_bio(bio, rq)
293 zero_fill_bio(bio);
294 break;
295 }
296 cond_resched();
297 }
298
299 return 0;
300 }
301
302 static void loop_clear_limits(struct loop_device *lo, int mode)
303 {
304 struct queue_limits lim = queue_limits_start_update(lo->lo_queue);
305
306 if (mode & FALLOC_FL_ZERO_RANGE)
307 lim.max_write_zeroes_sectors = 0;
308
309 if (mode & FALLOC_FL_PUNCH_HOLE) {
310 lim.max_hw_discard_sectors = 0;
311 lim.discard_granularity = 0;
312 }
313
314 queue_limits_commit_update(lo->lo_queue, &lim);
315 }
316
317 static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos,
318 int mode)
319 {
320 /*
321 * We use fallocate to manipulate the space mappings used by the image
322 * a.k.a. discard/zerorange.
323 */
324 struct file *file = lo->lo_backing_file;
325 int ret;
326
327 mode |= FALLOC_FL_KEEP_SIZE;
328
329 if (!bdev_max_discard_sectors(lo->lo_device))
330 return -EOPNOTSUPP;
331
332 ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
333 if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
334 return -EIO;
335
336 /*
337 * We initially configure the limits in a hope that fallocate is
338 * supported and clear them here if that turns out not to be true.
339 */
340 if (unlikely(ret == -EOPNOTSUPP))
341 loop_clear_limits(lo, mode);
342
343 return ret;
344 }
345
346 static int lo_req_flush(struct loop_device *lo, struct request *rq)
347 {
348 int ret = vfs_fsync(lo->lo_backing_file, 0);
349 if (unlikely(ret && ret != -EINVAL))
350 ret = -EIO;
351
352 return ret;
353 }
354
355 static void lo_complete_rq(struct request *rq)
356 {
357 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
358 blk_status_t ret = BLK_STS_OK;
359
360 if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) ||
361 req_op(rq) != REQ_OP_READ) {
362 if (cmd->ret < 0)
363 ret = errno_to_blk_status(cmd->ret);
364 goto end_io;
365 }
366
367 /*
368 * Short READ - if we got some data, advance our request and
369 * retry it. If we got no data, end the rest with EIO.
370 */
371 if (cmd->ret) {
372 blk_update_request(rq, BLK_STS_OK, cmd->ret);
373 cmd->ret = 0;
374 blk_mq_requeue_request(rq, true);
375 } else {
376 if (cmd->use_aio) {
377 struct bio *bio = rq->bio;
378
379 while (bio) {
380 zero_fill_bio(bio);
381 bio = bio->bi_next;
382 }
383 }
384 ret = BLK_STS_IOERR;
385 end_io:
386 blk_mq_end_request(rq, ret);
387 }
388 }
389
390 static void lo_rw_aio_do_completion(struct loop_cmd *cmd)
391 {
392 struct request *rq = blk_mq_rq_from_pdu(cmd);
393
394 if (!atomic_dec_and_test(&cmd->ref))
395 return;
396 kfree(cmd->bvec);
397 cmd->bvec = NULL;
398 if (likely(!blk_should_fake_timeout(rq->q)))
399 blk_mq_complete_request(rq);
400 }
401
402 static void lo_rw_aio_complete(struct kiocb *iocb, long ret)
403 {
404 struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb);
405
406 cmd->ret = ret;
407 lo_rw_aio_do_completion(cmd);
408 }
409
410 static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
411 loff_t pos, int rw)
412 {
413 struct iov_iter iter;
414 struct req_iterator rq_iter;
415 struct bio_vec *bvec;
416 struct request *rq = blk_mq_rq_from_pdu(cmd);
417 struct bio *bio = rq->bio;
418 struct file *file = lo->lo_backing_file;
419 struct bio_vec tmp;
420 unsigned int offset;
421 int nr_bvec = 0;
422 int ret;
423
424 rq_for_each_bvec(tmp, rq, rq_iter)
425 nr_bvec++;
426
427 if (rq->bio != rq->biotail) {
428
429 bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec),
430 GFP_NOIO);
431 if (!bvec)
432 return -EIO;
433 cmd->bvec = bvec;
434
435 /*
436 * The bios of the request may be started from the middle of
437 * the 'bvec' because of bio splitting, so we can't directly
438 * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec
439 * API will take care of all details for us.
440 */
441 rq_for_each_bvec(tmp, rq, rq_iter) {
442 *bvec = tmp;
443 bvec++;
444 }
445 bvec = cmd->bvec;
446 offset = 0;
447 } else {
448 /*
449 * Same here, this bio may be started from the middle of the
450 * 'bvec' because of bio splitting, so offset from the bvec
451 * must be passed to iov iterator
452 */
453 offset = bio->bi_iter.bi_bvec_done;
454 bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
455 }
456 atomic_set(&cmd->ref, 2);
457
458 iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq));
459 iter.iov_offset = offset;
460
461 cmd->iocb.ki_pos = pos;
462 cmd->iocb.ki_filp = file;
463 cmd->iocb.ki_complete = lo_rw_aio_complete;
464 cmd->iocb.ki_flags = IOCB_DIRECT;
465 cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
466
467 if (rw == ITER_SOURCE)
468 ret = file->f_op->write_iter(&cmd->iocb, &iter);
469 else
470 ret = file->f_op->read_iter(&cmd->iocb, &iter);
471
472 lo_rw_aio_do_completion(cmd);
473
474 if (ret != -EIOCBQUEUED)
475 lo_rw_aio_complete(&cmd->iocb, ret);
476 return 0;
477 }
478
479 static int do_req_filebacked(struct loop_device *lo, struct request *rq)
480 {
481 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
482 loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
483
484 /*
485 * lo_write_simple and lo_read_simple should have been covered
486 * by io submit style function like lo_rw_aio(), one blocker
487 * is that lo_read_simple() need to call flush_dcache_page after
488 * the page is written from kernel, and it isn't easy to handle
489 * this in io submit style function which submits all segments
490 * of the req at one time. And direct read IO doesn't need to
491 * run flush_dcache_page().
492 */
493 switch (req_op(rq)) {
494 case REQ_OP_FLUSH:
495 return lo_req_flush(lo, rq);
496 case REQ_OP_WRITE_ZEROES:
497 /*
498 * If the caller doesn't want deallocation, call zeroout to
499 * write zeroes the range. Otherwise, punch them out.
500 */
501 return lo_fallocate(lo, rq, pos,
502 (rq->cmd_flags & REQ_NOUNMAP) ?
503 FALLOC_FL_ZERO_RANGE :
504 FALLOC_FL_PUNCH_HOLE);
505 case REQ_OP_DISCARD:
506 return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE);
507 case REQ_OP_WRITE:
508 if (cmd->use_aio)
509 return lo_rw_aio(lo, cmd, pos, ITER_SOURCE);
510 else
511 return lo_write_simple(lo, rq, pos);
512 case REQ_OP_READ:
513 if (cmd->use_aio)
514 return lo_rw_aio(lo, cmd, pos, ITER_DEST);
515 else
516 return lo_read_simple(lo, rq, pos);
517 default:
518 WARN_ON_ONCE(1);
519 return -EIO;
520 }
521 }
522
523 static inline void loop_update_dio(struct loop_device *lo)
524 {
525 __loop_update_dio(lo, (lo->lo_backing_file->f_flags & O_DIRECT) |
526 lo->use_dio);
527 }
528
529 static void loop_reread_partitions(struct loop_device *lo)
530 {
531 int rc;
532
533 mutex_lock(&lo->lo_disk->open_mutex);
534 rc = bdev_disk_changed(lo->lo_disk, false);
535 mutex_unlock(&lo->lo_disk->open_mutex);
536 if (rc)
537 pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
538 __func__, lo->lo_number, lo->lo_file_name, rc);
539 }
540
541 static inline int is_loop_device(struct file *file)
542 {
543 struct inode *i = file->f_mapping->host;
544
545 return i && S_ISBLK(i->i_mode) && imajor(i) == LOOP_MAJOR;
546 }
547
548 static int loop_validate_file(struct file *file, struct block_device *bdev)
549 {
550 struct inode *inode = file->f_mapping->host;
551 struct file *f = file;
552
553 /* Avoid recursion */
554 while (is_loop_device(f)) {
555 struct loop_device *l;
556
557 lockdep_assert_held(&loop_validate_mutex);
558 if (f->f_mapping->host->i_rdev == bdev->bd_dev)
559 return -EBADF;
560
561 l = I_BDEV(f->f_mapping->host)->bd_disk->private_data;
562 if (l->lo_state != Lo_bound)
563 return -EINVAL;
564 /* Order wrt setting lo->lo_backing_file in loop_configure(). */
565 rmb();
566 f = l->lo_backing_file;
567 }
568 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
569 return -EINVAL;
570 return 0;
571 }
572
573 /*
574 * loop_change_fd switched the backing store of a loopback device to
575 * a new file. This is useful for operating system installers to free up
576 * the original file and in High Availability environments to switch to
577 * an alternative location for the content in case of server meltdown.
578 * This can only work if the loop device is used read-only, and if the
579 * new backing store is the same size and type as the old backing store.
580 */
581 static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
582 unsigned int arg)
583 {
584 struct file *file = fget(arg);
585 struct file *old_file;
586 int error;
587 bool partscan;
588 bool is_loop;
589
590 if (!file)
591 return -EBADF;
592
593 /* suppress uevents while reconfiguring the device */
594 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
595
596 is_loop = is_loop_device(file);
597 error = loop_global_lock_killable(lo, is_loop);
598 if (error)
599 goto out_putf;
600 error = -ENXIO;
601 if (lo->lo_state != Lo_bound)
602 goto out_err;
603
604 /* the loop device has to be read-only */
605 error = -EINVAL;
606 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
607 goto out_err;
608
609 error = loop_validate_file(file, bdev);
610 if (error)
611 goto out_err;
612
613 old_file = lo->lo_backing_file;
614
615 error = -EINVAL;
616
617 /* size of the new backing store needs to be the same */
618 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
619 goto out_err;
620
621 /* and ... switch */
622 disk_force_media_change(lo->lo_disk);
623 blk_mq_freeze_queue(lo->lo_queue);
624 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
625 lo->lo_backing_file = file;
626 lo->old_gfp_mask = mapping_gfp_mask(file->f_mapping);
627 mapping_set_gfp_mask(file->f_mapping,
628 lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
629 loop_update_dio(lo);
630 blk_mq_unfreeze_queue(lo->lo_queue);
631 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
632 loop_global_unlock(lo, is_loop);
633
634 /*
635 * Flush loop_validate_file() before fput(), for l->lo_backing_file
636 * might be pointing at old_file which might be the last reference.
637 */
638 if (!is_loop) {
639 mutex_lock(&loop_validate_mutex);
640 mutex_unlock(&loop_validate_mutex);
641 }
642 /*
643 * We must drop file reference outside of lo_mutex as dropping
644 * the file ref can take open_mutex which creates circular locking
645 * dependency.
646 */
647 fput(old_file);
648 if (partscan)
649 loop_reread_partitions(lo);
650
651 error = 0;
652 done:
653 /* enable and uncork uevent now that we are done */
654 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
655 return error;
656
657 out_err:
658 loop_global_unlock(lo, is_loop);
659 out_putf:
660 fput(file);
661 goto done;
662 }
663
664 /* loop sysfs attributes */
665
666 static ssize_t loop_attr_show(struct device *dev, char *page,
667 ssize_t (*callback)(struct loop_device *, char *))
668 {
669 struct gendisk *disk = dev_to_disk(dev);
670 struct loop_device *lo = disk->private_data;
671
672 return callback(lo, page);
673 }
674
675 #define LOOP_ATTR_RO(_name) \
676 static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
677 static ssize_t loop_attr_do_show_##_name(struct device *d, \
678 struct device_attribute *attr, char *b) \
679 { \
680 return loop_attr_show(d, b, loop_attr_##_name##_show); \
681 } \
682 static struct device_attribute loop_attr_##_name = \
683 __ATTR(_name, 0444, loop_attr_do_show_##_name, NULL);
684
685 static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
686 {
687 ssize_t ret;
688 char *p = NULL;
689
690 spin_lock_irq(&lo->lo_lock);
691 if (lo->lo_backing_file)
692 p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1);
693 spin_unlock_irq(&lo->lo_lock);
694
695 if (IS_ERR_OR_NULL(p))
696 ret = PTR_ERR(p);
697 else {
698 ret = strlen(p);
699 memmove(buf, p, ret);
700 buf[ret++] = '\n';
701 buf[ret] = 0;
702 }
703
704 return ret;
705 }
706
707 static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
708 {
709 return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_offset);
710 }
711
712 static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
713 {
714 return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
715 }
716
717 static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
718 {
719 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
720
721 return sysfs_emit(buf, "%s\n", autoclear ? "1" : "0");
722 }
723
724 static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
725 {
726 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
727
728 return sysfs_emit(buf, "%s\n", partscan ? "1" : "0");
729 }
730
731 static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf)
732 {
733 int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO);
734
735 return sysfs_emit(buf, "%s\n", dio ? "1" : "0");
736 }
737
738 LOOP_ATTR_RO(backing_file);
739 LOOP_ATTR_RO(offset);
740 LOOP_ATTR_RO(sizelimit);
741 LOOP_ATTR_RO(autoclear);
742 LOOP_ATTR_RO(partscan);
743 LOOP_ATTR_RO(dio);
744
745 static struct attribute *loop_attrs[] = {
746 &loop_attr_backing_file.attr,
747 &loop_attr_offset.attr,
748 &loop_attr_sizelimit.attr,
749 &loop_attr_autoclear.attr,
750 &loop_attr_partscan.attr,
751 &loop_attr_dio.attr,
752 NULL,
753 };
754
755 static struct attribute_group loop_attribute_group = {
756 .name = "loop",
757 .attrs= loop_attrs,
758 };
759
760 static void loop_sysfs_init(struct loop_device *lo)
761 {
762 lo->sysfs_inited = !sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
763 &loop_attribute_group);
764 }
765
766 static void loop_sysfs_exit(struct loop_device *lo)
767 {
768 if (lo->sysfs_inited)
769 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
770 &loop_attribute_group);
771 }
772
773 static void loop_config_discard(struct loop_device *lo,
774 struct queue_limits *lim)
775 {
776 struct file *file = lo->lo_backing_file;
777 struct inode *inode = file->f_mapping->host;
778 u32 granularity = 0, max_discard_sectors = 0;
779 struct kstatfs sbuf;
780
781 /*
782 * If the backing device is a block device, mirror its zeroing
783 * capability. Set the discard sectors to the block device's zeroing
784 * capabilities because loop discards result in blkdev_issue_zeroout(),
785 * not blkdev_issue_discard(). This maintains consistent behavior with
786 * file-backed loop devices: discarded regions read back as zero.
787 */
788 if (S_ISBLK(inode->i_mode)) {
789 struct request_queue *backingq = bdev_get_queue(I_BDEV(inode));
790
791 max_discard_sectors = backingq->limits.max_write_zeroes_sectors;
792 granularity = bdev_discard_granularity(I_BDEV(inode)) ?:
793 queue_physical_block_size(backingq);
794
795 /*
796 * We use punch hole to reclaim the free space used by the
797 * image a.k.a. discard.
798 */
799 } else if (file->f_op->fallocate && !vfs_statfs(&file->f_path, &sbuf)) {
800 max_discard_sectors = UINT_MAX >> 9;
801 granularity = sbuf.f_bsize;
802 }
803
804 lim->max_hw_discard_sectors = max_discard_sectors;
805 lim->max_write_zeroes_sectors = max_discard_sectors;
806 if (max_discard_sectors)
807 lim->discard_granularity = granularity;
808 else
809 lim->discard_granularity = 0;
810 }
811
812 struct loop_worker {
813 struct rb_node rb_node;
814 struct work_struct work;
815 struct list_head cmd_list;
816 struct list_head idle_list;
817 struct loop_device *lo;
818 struct cgroup_subsys_state *blkcg_css;
819 unsigned long last_ran_at;
820 };
821
822 static void loop_workfn(struct work_struct *work);
823
824 #ifdef CONFIG_BLK_CGROUP
825 static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
826 {
827 return !css || css == blkcg_root_css;
828 }
829 #else
830 static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
831 {
832 return !css;
833 }
834 #endif
835
836 static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd)
837 {
838 struct rb_node **node, *parent = NULL;
839 struct loop_worker *cur_worker, *worker = NULL;
840 struct work_struct *work;
841 struct list_head *cmd_list;
842
843 spin_lock_irq(&lo->lo_work_lock);
844
845 if (queue_on_root_worker(cmd->blkcg_css))
846 goto queue_work;
847
848 node = &lo->worker_tree.rb_node;
849
850 while (*node) {
851 parent = *node;
852 cur_worker = container_of(*node, struct loop_worker, rb_node);
853 if (cur_worker->blkcg_css == cmd->blkcg_css) {
854 worker = cur_worker;
855 break;
856 } else if ((long)cur_worker->blkcg_css < (long)cmd->blkcg_css) {
857 node = &(*node)->rb_left;
858 } else {
859 node = &(*node)->rb_right;
860 }
861 }
862 if (worker)
863 goto queue_work;
864
865 worker = kzalloc(sizeof(struct loop_worker), GFP_NOWAIT | __GFP_NOWARN);
866 /*
867 * In the event we cannot allocate a worker, just queue on the
868 * rootcg worker and issue the I/O as the rootcg
869 */
870 if (!worker) {
871 cmd->blkcg_css = NULL;
872 if (cmd->memcg_css)
873 css_put(cmd->memcg_css);
874 cmd->memcg_css = NULL;
875 goto queue_work;
876 }
877
878 worker->blkcg_css = cmd->blkcg_css;
879 css_get(worker->blkcg_css);
880 INIT_WORK(&worker->work, loop_workfn);
881 INIT_LIST_HEAD(&worker->cmd_list);
882 INIT_LIST_HEAD(&worker->idle_list);
883 worker->lo = lo;
884 rb_link_node(&worker->rb_node, parent, node);
885 rb_insert_color(&worker->rb_node, &lo->worker_tree);
886 queue_work:
887 if (worker) {
888 /*
889 * We need to remove from the idle list here while
890 * holding the lock so that the idle timer doesn't
891 * free the worker
892 */
893 if (!list_empty(&worker->idle_list))
894 list_del_init(&worker->idle_list);
895 work = &worker->work;
896 cmd_list = &worker->cmd_list;
897 } else {
898 work = &lo->rootcg_work;
899 cmd_list = &lo->rootcg_cmd_list;
900 }
901 list_add_tail(&cmd->list_entry, cmd_list);
902 queue_work(lo->workqueue, work);
903 spin_unlock_irq(&lo->lo_work_lock);
904 }
905
906 static void loop_set_timer(struct loop_device *lo)
907 {
908 timer_reduce(&lo->timer, jiffies + LOOP_IDLE_WORKER_TIMEOUT);
909 }
910
911 static void loop_free_idle_workers(struct loop_device *lo, bool delete_all)
912 {
913 struct loop_worker *pos, *worker;
914
915 spin_lock_irq(&lo->lo_work_lock);
916 list_for_each_entry_safe(worker, pos, &lo->idle_worker_list,
917 idle_list) {
918 if (!delete_all &&
919 time_is_after_jiffies(worker->last_ran_at +
920 LOOP_IDLE_WORKER_TIMEOUT))
921 break;
922 list_del(&worker->idle_list);
923 rb_erase(&worker->rb_node, &lo->worker_tree);
924 css_put(worker->blkcg_css);
925 kfree(worker);
926 }
927 if (!list_empty(&lo->idle_worker_list))
928 loop_set_timer(lo);
929 spin_unlock_irq(&lo->lo_work_lock);
930 }
931
932 static void loop_free_idle_workers_timer(struct timer_list *timer)
933 {
934 struct loop_device *lo = container_of(timer, struct loop_device, timer);
935
936 return loop_free_idle_workers(lo, false);
937 }
938
939 /**
940 * loop_set_status_from_info - configure device from loop_info
941 * @lo: struct loop_device to configure
942 * @info: struct loop_info64 to configure the device with
943 *
944 * Configures the loop device parameters according to the passed
945 * in loop_info64 configuration.
946 */
947 static int
948 loop_set_status_from_info(struct loop_device *lo,
949 const struct loop_info64 *info)
950 {
951 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
952 return -EINVAL;
953
954 switch (info->lo_encrypt_type) {
955 case LO_CRYPT_NONE:
956 break;
957 case LO_CRYPT_XOR:
958 pr_warn("support for the xor transformation has been removed.\n");
959 return -EINVAL;
960 case LO_CRYPT_CRYPTOAPI:
961 pr_warn("support for cryptoloop has been removed. Use dm-crypt instead.\n");
962 return -EINVAL;
963 default:
964 return -EINVAL;
965 }
966
967 /* Avoid assigning overflow values */
968 if (info->lo_offset > LLONG_MAX || info->lo_sizelimit > LLONG_MAX)
969 return -EOVERFLOW;
970
971 lo->lo_offset = info->lo_offset;
972 lo->lo_sizelimit = info->lo_sizelimit;
973
974 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
975 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
976 lo->lo_flags = info->lo_flags;
977 return 0;
978 }
979
980 static unsigned short loop_default_blocksize(struct loop_device *lo,
981 struct block_device *backing_bdev)
982 {
983 /* In case of direct I/O, match underlying block size */
984 if ((lo->lo_backing_file->f_flags & O_DIRECT) && backing_bdev)
985 return bdev_logical_block_size(backing_bdev);
986 return SECTOR_SIZE;
987 }
988
989 static int loop_reconfigure_limits(struct loop_device *lo, unsigned short bsize)
990 {
991 struct file *file = lo->lo_backing_file;
992 struct inode *inode = file->f_mapping->host;
993 struct block_device *backing_bdev = NULL;
994 struct queue_limits lim;
995
996 if (S_ISBLK(inode->i_mode))
997 backing_bdev = I_BDEV(inode);
998 else if (inode->i_sb->s_bdev)
999 backing_bdev = inode->i_sb->s_bdev;
1000
1001 if (!bsize)
1002 bsize = loop_default_blocksize(lo, backing_bdev);
1003
1004 lim = queue_limits_start_update(lo->lo_queue);
1005 lim.logical_block_size = bsize;
1006 lim.physical_block_size = bsize;
1007 lim.io_min = bsize;
1008 lim.features &= ~(BLK_FEAT_WRITE_CACHE | BLK_FEAT_ROTATIONAL);
1009 if (file->f_op->fsync && !(lo->lo_flags & LO_FLAGS_READ_ONLY))
1010 lim.features |= BLK_FEAT_WRITE_CACHE;
1011 if (backing_bdev && !bdev_nonrot(backing_bdev))
1012 lim.features |= BLK_FEAT_ROTATIONAL;
1013 loop_config_discard(lo, &lim);
1014 return queue_limits_commit_update(lo->lo_queue, &lim);
1015 }
1016
1017 static int loop_configure(struct loop_device *lo, blk_mode_t mode,
1018 struct block_device *bdev,
1019 const struct loop_config *config)
1020 {
1021 struct file *file = fget(config->fd);
1022 struct address_space *mapping;
1023 int error;
1024 loff_t size;
1025 bool partscan;
1026 bool is_loop;
1027
1028 if (!file)
1029 return -EBADF;
1030 is_loop = is_loop_device(file);
1031
1032 /* This is safe, since we have a reference from open(). */
1033 __module_get(THIS_MODULE);
1034
1035 /*
1036 * If we don't hold exclusive handle for the device, upgrade to it
1037 * here to avoid changing device under exclusive owner.
1038 */
1039 if (!(mode & BLK_OPEN_EXCL)) {
1040 error = bd_prepare_to_claim(bdev, loop_configure, NULL);
1041 if (error)
1042 goto out_putf;
1043 }
1044
1045 error = loop_global_lock_killable(lo, is_loop);
1046 if (error)
1047 goto out_bdev;
1048
1049 error = -EBUSY;
1050 if (lo->lo_state != Lo_unbound)
1051 goto out_unlock;
1052
1053 error = loop_validate_file(file, bdev);
1054 if (error)
1055 goto out_unlock;
1056
1057 mapping = file->f_mapping;
1058
1059 if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) {
1060 error = -EINVAL;
1061 goto out_unlock;
1062 }
1063
1064 error = loop_set_status_from_info(lo, &config->info);
1065 if (error)
1066 goto out_unlock;
1067
1068 if (!(file->f_mode & FMODE_WRITE) || !(mode & BLK_OPEN_WRITE) ||
1069 !file->f_op->write_iter)
1070 lo->lo_flags |= LO_FLAGS_READ_ONLY;
1071
1072 if (!lo->workqueue) {
1073 lo->workqueue = alloc_workqueue("loop%d",
1074 WQ_UNBOUND | WQ_FREEZABLE,
1075 0, lo->lo_number);
1076 if (!lo->workqueue) {
1077 error = -ENOMEM;
1078 goto out_unlock;
1079 }
1080 }
1081
1082 /* suppress uevents while reconfiguring the device */
1083 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
1084
1085 disk_force_media_change(lo->lo_disk);
1086 set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0);
1087
1088 lo->use_dio = lo->lo_flags & LO_FLAGS_DIRECT_IO;
1089 lo->lo_device = bdev;
1090 lo->lo_backing_file = file;
1091 lo->old_gfp_mask = mapping_gfp_mask(mapping);
1092 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
1093
1094 error = loop_reconfigure_limits(lo, config->block_size);
1095 if (error)
1096 goto out_unlock;
1097
1098 loop_update_dio(lo);
1099 loop_sysfs_init(lo);
1100
1101 size = get_loop_size(lo, file);
1102 loop_set_size(lo, size);
1103
1104 /* Order wrt reading lo_state in loop_validate_file(). */
1105 wmb();
1106
1107 lo->lo_state = Lo_bound;
1108 if (part_shift)
1109 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1110 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
1111 if (partscan)
1112 clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1113
1114 /* enable and uncork uevent now that we are done */
1115 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
1116
1117 loop_global_unlock(lo, is_loop);
1118 if (partscan)
1119 loop_reread_partitions(lo);
1120
1121 if (!(mode & BLK_OPEN_EXCL))
1122 bd_abort_claiming(bdev, loop_configure);
1123
1124 return 0;
1125
1126 out_unlock:
1127 loop_global_unlock(lo, is_loop);
1128 out_bdev:
1129 if (!(mode & BLK_OPEN_EXCL))
1130 bd_abort_claiming(bdev, loop_configure);
1131 out_putf:
1132 fput(file);
1133 /* This is safe: open() is still holding a reference. */
1134 module_put(THIS_MODULE);
1135 return error;
1136 }
1137
1138 static void __loop_clr_fd(struct loop_device *lo)
1139 {
1140 struct queue_limits lim;
1141 struct file *filp;
1142 gfp_t gfp = lo->old_gfp_mask;
1143
1144 spin_lock_irq(&lo->lo_lock);
1145 filp = lo->lo_backing_file;
1146 lo->lo_backing_file = NULL;
1147 spin_unlock_irq(&lo->lo_lock);
1148
1149 lo->lo_device = NULL;
1150 lo->lo_offset = 0;
1151 lo->lo_sizelimit = 0;
1152 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1153
1154 /* reset the block size to the default */
1155 lim = queue_limits_start_update(lo->lo_queue);
1156 lim.logical_block_size = SECTOR_SIZE;
1157 lim.physical_block_size = SECTOR_SIZE;
1158 lim.io_min = SECTOR_SIZE;
1159 queue_limits_commit_update(lo->lo_queue, &lim);
1160
1161 invalidate_disk(lo->lo_disk);
1162 loop_sysfs_exit(lo);
1163 /* let user-space know about this change */
1164 kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
1165 mapping_set_gfp_mask(filp->f_mapping, gfp);
1166 /* This is safe: open() is still holding a reference. */
1167 module_put(THIS_MODULE);
1168
1169 disk_force_media_change(lo->lo_disk);
1170
1171 if (lo->lo_flags & LO_FLAGS_PARTSCAN) {
1172 int err;
1173
1174 /*
1175 * open_mutex has been held already in release path, so don't
1176 * acquire it if this function is called in such case.
1177 *
1178 * If the reread partition isn't from release path, lo_refcnt
1179 * must be at least one and it can only become zero when the
1180 * current holder is released.
1181 */
1182 err = bdev_disk_changed(lo->lo_disk, false);
1183 if (err)
1184 pr_warn("%s: partition scan of loop%d failed (rc=%d)\n",
1185 __func__, lo->lo_number, err);
1186 /* Device is gone, no point in returning error */
1187 }
1188
1189 /*
1190 * lo->lo_state is set to Lo_unbound here after above partscan has
1191 * finished. There cannot be anybody else entering __loop_clr_fd() as
1192 * Lo_rundown state protects us from all the other places trying to
1193 * change the 'lo' device.
1194 */
1195 lo->lo_flags = 0;
1196 if (!part_shift)
1197 set_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1198 mutex_lock(&lo->lo_mutex);
1199 lo->lo_state = Lo_unbound;
1200 mutex_unlock(&lo->lo_mutex);
1201
1202 /*
1203 * Need not hold lo_mutex to fput backing file. Calling fput holding
1204 * lo_mutex triggers a circular lock dependency possibility warning as
1205 * fput can take open_mutex which is usually taken before lo_mutex.
1206 */
1207 fput(filp);
1208 }
1209
1210 static int loop_clr_fd(struct loop_device *lo)
1211 {
1212 int err;
1213
1214 /*
1215 * Since lo_ioctl() is called without locks held, it is possible that
1216 * loop_configure()/loop_change_fd() and loop_clr_fd() run in parallel.
1217 *
1218 * Therefore, use global lock when setting Lo_rundown state in order to
1219 * make sure that loop_validate_file() will fail if the "struct file"
1220 * which loop_configure()/loop_change_fd() found via fget() was this
1221 * loop device.
1222 */
1223 err = loop_global_lock_killable(lo, true);
1224 if (err)
1225 return err;
1226 if (lo->lo_state != Lo_bound) {
1227 loop_global_unlock(lo, true);
1228 return -ENXIO;
1229 }
1230 /*
1231 * Mark the device for removing the backing device on last close.
1232 * If we are the only opener, also switch the state to roundown here to
1233 * prevent new openers from coming in.
1234 */
1235
1236 lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
1237 if (disk_openers(lo->lo_disk) == 1)
1238 lo->lo_state = Lo_rundown;
1239 loop_global_unlock(lo, true);
1240
1241 return 0;
1242 }
1243
1244 static int
1245 loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1246 {
1247 int err;
1248 int prev_lo_flags;
1249 bool partscan = false;
1250 bool size_changed = false;
1251
1252 err = mutex_lock_killable(&lo->lo_mutex);
1253 if (err)
1254 return err;
1255 if (lo->lo_state != Lo_bound) {
1256 err = -ENXIO;
1257 goto out_unlock;
1258 }
1259
1260 if (lo->lo_offset != info->lo_offset ||
1261 lo->lo_sizelimit != info->lo_sizelimit) {
1262 size_changed = true;
1263 sync_blockdev(lo->lo_device);
1264 invalidate_bdev(lo->lo_device);
1265 }
1266
1267 /* I/O need to be drained during transfer transition */
1268 blk_mq_freeze_queue(lo->lo_queue);
1269
1270 prev_lo_flags = lo->lo_flags;
1271
1272 err = loop_set_status_from_info(lo, info);
1273 if (err)
1274 goto out_unfreeze;
1275
1276 /* Mask out flags that can't be set using LOOP_SET_STATUS. */
1277 lo->lo_flags &= LOOP_SET_STATUS_SETTABLE_FLAGS;
1278 /* For those flags, use the previous values instead */
1279 lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_SETTABLE_FLAGS;
1280 /* For flags that can't be cleared, use previous values too */
1281 lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_CLEARABLE_FLAGS;
1282
1283 if (size_changed) {
1284 loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit,
1285 lo->lo_backing_file);
1286 loop_set_size(lo, new_size);
1287 }
1288
1289 /* update dio if lo_offset or transfer is changed */
1290 __loop_update_dio(lo, lo->use_dio);
1291
1292 out_unfreeze:
1293 blk_mq_unfreeze_queue(lo->lo_queue);
1294
1295 if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) &&
1296 !(prev_lo_flags & LO_FLAGS_PARTSCAN)) {
1297 clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1298 partscan = true;
1299 }
1300 out_unlock:
1301 mutex_unlock(&lo->lo_mutex);
1302 if (partscan)
1303 loop_reread_partitions(lo);
1304
1305 return err;
1306 }
1307
1308 static int
1309 loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1310 {
1311 struct path path;
1312 struct kstat stat;
1313 int ret;
1314
1315 ret = mutex_lock_killable(&lo->lo_mutex);
1316 if (ret)
1317 return ret;
1318 if (lo->lo_state != Lo_bound) {
1319 mutex_unlock(&lo->lo_mutex);
1320 return -ENXIO;
1321 }
1322
1323 memset(info, 0, sizeof(*info));
1324 info->lo_number = lo->lo_number;
1325 info->lo_offset = lo->lo_offset;
1326 info->lo_sizelimit = lo->lo_sizelimit;
1327 info->lo_flags = lo->lo_flags;
1328 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1329
1330 /* Drop lo_mutex while we call into the filesystem. */
1331 path = lo->lo_backing_file->f_path;
1332 path_get(&path);
1333 mutex_unlock(&lo->lo_mutex);
1334 ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT);
1335 if (!ret) {
1336 info->lo_device = huge_encode_dev(stat.dev);
1337 info->lo_inode = stat.ino;
1338 info->lo_rdevice = huge_encode_dev(stat.rdev);
1339 }
1340 path_put(&path);
1341 return ret;
1342 }
1343
1344 static void
1345 loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1346 {
1347 memset(info64, 0, sizeof(*info64));
1348 info64->lo_number = info->lo_number;
1349 info64->lo_device = info->lo_device;
1350 info64->lo_inode = info->lo_inode;
1351 info64->lo_rdevice = info->lo_rdevice;
1352 info64->lo_offset = info->lo_offset;
1353 info64->lo_sizelimit = 0;
1354 info64->lo_flags = info->lo_flags;
1355 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1356 }
1357
1358 static int
1359 loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1360 {
1361 memset(info, 0, sizeof(*info));
1362 info->lo_number = info64->lo_number;
1363 info->lo_device = info64->lo_device;
1364 info->lo_inode = info64->lo_inode;
1365 info->lo_rdevice = info64->lo_rdevice;
1366 info->lo_offset = info64->lo_offset;
1367 info->lo_flags = info64->lo_flags;
1368 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1369
1370 /* error in case values were truncated */
1371 if (info->lo_device != info64->lo_device ||
1372 info->lo_rdevice != info64->lo_rdevice ||
1373 info->lo_inode != info64->lo_inode ||
1374 info->lo_offset != info64->lo_offset)
1375 return -EOVERFLOW;
1376
1377 return 0;
1378 }
1379
1380 static int
1381 loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1382 {
1383 struct loop_info info;
1384 struct loop_info64 info64;
1385
1386 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1387 return -EFAULT;
1388 loop_info64_from_old(&info, &info64);
1389 return loop_set_status(lo, &info64);
1390 }
1391
1392 static int
1393 loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1394 {
1395 struct loop_info64 info64;
1396
1397 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1398 return -EFAULT;
1399 return loop_set_status(lo, &info64);
1400 }
1401
1402 static int
1403 loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1404 struct loop_info info;
1405 struct loop_info64 info64;
1406 int err;
1407
1408 if (!arg)
1409 return -EINVAL;
1410 err = loop_get_status(lo, &info64);
1411 if (!err)
1412 err = loop_info64_to_old(&info64, &info);
1413 if (!err && copy_to_user(arg, &info, sizeof(info)))
1414 err = -EFAULT;
1415
1416 return err;
1417 }
1418
1419 static int
1420 loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1421 struct loop_info64 info64;
1422 int err;
1423
1424 if (!arg)
1425 return -EINVAL;
1426 err = loop_get_status(lo, &info64);
1427 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1428 err = -EFAULT;
1429
1430 return err;
1431 }
1432
1433 static int loop_set_capacity(struct loop_device *lo)
1434 {
1435 loff_t size;
1436
1437 if (unlikely(lo->lo_state != Lo_bound))
1438 return -ENXIO;
1439
1440 size = get_loop_size(lo, lo->lo_backing_file);
1441 loop_set_size(lo, size);
1442
1443 return 0;
1444 }
1445
1446 static int loop_set_dio(struct loop_device *lo, unsigned long arg)
1447 {
1448 int error = -ENXIO;
1449 if (lo->lo_state != Lo_bound)
1450 goto out;
1451
1452 __loop_update_dio(lo, !!arg);
1453 if (lo->use_dio == !!arg)
1454 return 0;
1455 error = -EINVAL;
1456 out:
1457 return error;
1458 }
1459
1460 static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
1461 {
1462 int err = 0;
1463
1464 if (lo->lo_state != Lo_bound)
1465 return -ENXIO;
1466
1467 if (lo->lo_queue->limits.logical_block_size == arg)
1468 return 0;
1469
1470 sync_blockdev(lo->lo_device);
1471 invalidate_bdev(lo->lo_device);
1472
1473 blk_mq_freeze_queue(lo->lo_queue);
1474 err = loop_reconfigure_limits(lo, arg);
1475 loop_update_dio(lo);
1476 blk_mq_unfreeze_queue(lo->lo_queue);
1477
1478 return err;
1479 }
1480
1481 static int lo_simple_ioctl(struct loop_device *lo, unsigned int cmd,
1482 unsigned long arg)
1483 {
1484 int err;
1485
1486 err = mutex_lock_killable(&lo->lo_mutex);
1487 if (err)
1488 return err;
1489 switch (cmd) {
1490 case LOOP_SET_CAPACITY:
1491 err = loop_set_capacity(lo);
1492 break;
1493 case LOOP_SET_DIRECT_IO:
1494 err = loop_set_dio(lo, arg);
1495 break;
1496 case LOOP_SET_BLOCK_SIZE:
1497 err = loop_set_block_size(lo, arg);
1498 break;
1499 default:
1500 err = -EINVAL;
1501 }
1502 mutex_unlock(&lo->lo_mutex);
1503 return err;
1504 }
1505
1506 static int lo_ioctl(struct block_device *bdev, blk_mode_t mode,
1507 unsigned int cmd, unsigned long arg)
1508 {
1509 struct loop_device *lo = bdev->bd_disk->private_data;
1510 void __user *argp = (void __user *) arg;
1511 int err;
1512
1513 switch (cmd) {
1514 case LOOP_SET_FD: {
1515 /*
1516 * Legacy case - pass in a zeroed out struct loop_config with
1517 * only the file descriptor set , which corresponds with the
1518 * default parameters we'd have used otherwise.
1519 */
1520 struct loop_config config;
1521
1522 memset(&config, 0, sizeof(config));
1523 config.fd = arg;
1524
1525 return loop_configure(lo, mode, bdev, &config);
1526 }
1527 case LOOP_CONFIGURE: {
1528 struct loop_config config;
1529
1530 if (copy_from_user(&config, argp, sizeof(config)))
1531 return -EFAULT;
1532
1533 return loop_configure(lo, mode, bdev, &config);
1534 }
1535 case LOOP_CHANGE_FD:
1536 return loop_change_fd(lo, bdev, arg);
1537 case LOOP_CLR_FD:
1538 return loop_clr_fd(lo);
1539 case LOOP_SET_STATUS:
1540 err = -EPERM;
1541 if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN))
1542 err = loop_set_status_old(lo, argp);
1543 break;
1544 case LOOP_GET_STATUS:
1545 return loop_get_status_old(lo, argp);
1546 case LOOP_SET_STATUS64:
1547 err = -EPERM;
1548 if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN))
1549 err = loop_set_status64(lo, argp);
1550 break;
1551 case LOOP_GET_STATUS64:
1552 return loop_get_status64(lo, argp);
1553 case LOOP_SET_CAPACITY:
1554 case LOOP_SET_DIRECT_IO:
1555 case LOOP_SET_BLOCK_SIZE:
1556 if (!(mode & BLK_OPEN_WRITE) && !capable(CAP_SYS_ADMIN))
1557 return -EPERM;
1558 fallthrough;
1559 default:
1560 err = lo_simple_ioctl(lo, cmd, arg);
1561 break;
1562 }
1563
1564 return err;
1565 }
1566
1567 #ifdef CONFIG_COMPAT
1568 struct compat_loop_info {
1569 compat_int_t lo_number; /* ioctl r/o */
1570 compat_dev_t lo_device; /* ioctl r/o */
1571 compat_ulong_t lo_inode; /* ioctl r/o */
1572 compat_dev_t lo_rdevice; /* ioctl r/o */
1573 compat_int_t lo_offset;
1574 compat_int_t lo_encrypt_type; /* obsolete, ignored */
1575 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1576 compat_int_t lo_flags; /* ioctl r/o */
1577 char lo_name[LO_NAME_SIZE];
1578 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1579 compat_ulong_t lo_init[2];
1580 char reserved[4];
1581 };
1582
1583 /*
1584 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1585 * - noinlined to reduce stack space usage in main part of driver
1586 */
1587 static noinline int
1588 loop_info64_from_compat(const struct compat_loop_info __user *arg,
1589 struct loop_info64 *info64)
1590 {
1591 struct compat_loop_info info;
1592
1593 if (copy_from_user(&info, arg, sizeof(info)))
1594 return -EFAULT;
1595
1596 memset(info64, 0, sizeof(*info64));
1597 info64->lo_number = info.lo_number;
1598 info64->lo_device = info.lo_device;
1599 info64->lo_inode = info.lo_inode;
1600 info64->lo_rdevice = info.lo_rdevice;
1601 info64->lo_offset = info.lo_offset;
1602 info64->lo_sizelimit = 0;
1603 info64->lo_flags = info.lo_flags;
1604 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1605 return 0;
1606 }
1607
1608 /*
1609 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1610 * - noinlined to reduce stack space usage in main part of driver
1611 */
1612 static noinline int
1613 loop_info64_to_compat(const struct loop_info64 *info64,
1614 struct compat_loop_info __user *arg)
1615 {
1616 struct compat_loop_info info;
1617
1618 memset(&info, 0, sizeof(info));
1619 info.lo_number = info64->lo_number;
1620 info.lo_device = info64->lo_device;
1621 info.lo_inode = info64->lo_inode;
1622 info.lo_rdevice = info64->lo_rdevice;
1623 info.lo_offset = info64->lo_offset;
1624 info.lo_flags = info64->lo_flags;
1625 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1626
1627 /* error in case values were truncated */
1628 if (info.lo_device != info64->lo_device ||
1629 info.lo_rdevice != info64->lo_rdevice ||
1630 info.lo_inode != info64->lo_inode ||
1631 info.lo_offset != info64->lo_offset)
1632 return -EOVERFLOW;
1633
1634 if (copy_to_user(arg, &info, sizeof(info)))
1635 return -EFAULT;
1636 return 0;
1637 }
1638
1639 static int
1640 loop_set_status_compat(struct loop_device *lo,
1641 const struct compat_loop_info __user *arg)
1642 {
1643 struct loop_info64 info64;
1644 int ret;
1645
1646 ret = loop_info64_from_compat(arg, &info64);
1647 if (ret < 0)
1648 return ret;
1649 return loop_set_status(lo, &info64);
1650 }
1651
1652 static int
1653 loop_get_status_compat(struct loop_device *lo,
1654 struct compat_loop_info __user *arg)
1655 {
1656 struct loop_info64 info64;
1657 int err;
1658
1659 if (!arg)
1660 return -EINVAL;
1661 err = loop_get_status(lo, &info64);
1662 if (!err)
1663 err = loop_info64_to_compat(&info64, arg);
1664 return err;
1665 }
1666
1667 static int lo_compat_ioctl(struct block_device *bdev, blk_mode_t mode,
1668 unsigned int cmd, unsigned long arg)
1669 {
1670 struct loop_device *lo = bdev->bd_disk->private_data;
1671 int err;
1672
1673 switch(cmd) {
1674 case LOOP_SET_STATUS:
1675 err = loop_set_status_compat(lo,
1676 (const struct compat_loop_info __user *)arg);
1677 break;
1678 case LOOP_GET_STATUS:
1679 err = loop_get_status_compat(lo,
1680 (struct compat_loop_info __user *)arg);
1681 break;
1682 case LOOP_SET_CAPACITY:
1683 case LOOP_CLR_FD:
1684 case LOOP_GET_STATUS64:
1685 case LOOP_SET_STATUS64:
1686 case LOOP_CONFIGURE:
1687 arg = (unsigned long) compat_ptr(arg);
1688 fallthrough;
1689 case LOOP_SET_FD:
1690 case LOOP_CHANGE_FD:
1691 case LOOP_SET_BLOCK_SIZE:
1692 case LOOP_SET_DIRECT_IO:
1693 err = lo_ioctl(bdev, mode, cmd, arg);
1694 break;
1695 default:
1696 err = -ENOIOCTLCMD;
1697 break;
1698 }
1699 return err;
1700 }
1701 #endif
1702
1703 static int lo_open(struct gendisk *disk, blk_mode_t mode)
1704 {
1705 struct loop_device *lo = disk->private_data;
1706 int err;
1707
1708 err = mutex_lock_killable(&lo->lo_mutex);
1709 if (err)
1710 return err;
1711
1712 if (lo->lo_state == Lo_deleting || lo->lo_state == Lo_rundown)
1713 err = -ENXIO;
1714 mutex_unlock(&lo->lo_mutex);
1715 return err;
1716 }
1717
1718 static void lo_release(struct gendisk *disk)
1719 {
1720 struct loop_device *lo = disk->private_data;
1721 bool need_clear = false;
1722
1723 if (disk_openers(disk) > 0)
1724 return;
1725 /*
1726 * Clear the backing device information if this is the last close of
1727 * a device that's been marked for auto clear, or on which LOOP_CLR_FD
1728 * has been called.
1729 */
1730
1731 mutex_lock(&lo->lo_mutex);
1732 if (lo->lo_state == Lo_bound && (lo->lo_flags & LO_FLAGS_AUTOCLEAR))
1733 lo->lo_state = Lo_rundown;
1734
1735 need_clear = (lo->lo_state == Lo_rundown);
1736 mutex_unlock(&lo->lo_mutex);
1737
1738 if (need_clear)
1739 __loop_clr_fd(lo);
1740 }
1741
1742 static void lo_free_disk(struct gendisk *disk)
1743 {
1744 struct loop_device *lo = disk->private_data;
1745
1746 if (lo->workqueue)
1747 destroy_workqueue(lo->workqueue);
1748 loop_free_idle_workers(lo, true);
1749 timer_shutdown_sync(&lo->timer);
1750 mutex_destroy(&lo->lo_mutex);
1751 kfree(lo);
1752 }
1753
1754 static const struct block_device_operations lo_fops = {
1755 .owner = THIS_MODULE,
1756 .open = lo_open,
1757 .release = lo_release,
1758 .ioctl = lo_ioctl,
1759 #ifdef CONFIG_COMPAT
1760 .compat_ioctl = lo_compat_ioctl,
1761 #endif
1762 .free_disk = lo_free_disk,
1763 };
1764
1765 /*
1766 * And now the modules code and kernel interface.
1767 */
1768
1769 /*
1770 * If max_loop is specified, create that many devices upfront.
1771 * This also becomes a hard limit. If max_loop is not specified,
1772 * the default isn't a hard limit (as before commit 85c50197716c
1773 * changed the default value from 0 for max_loop=0 reasons), just
1774 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1775 * init time. Loop devices can be requested on-demand with the
1776 * /dev/loop-control interface, or be instantiated by accessing
1777 * a 'dead' device node.
1778 */
1779 static int max_loop = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1780
1781 #ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
1782 static bool max_loop_specified;
1783
1784 static int max_loop_param_set_int(const char *val,
1785 const struct kernel_param *kp)
1786 {
1787 int ret;
1788
1789 ret = param_set_int(val, kp);
1790 if (ret < 0)
1791 return ret;
1792
1793 max_loop_specified = true;
1794 return 0;
1795 }
1796
1797 static const struct kernel_param_ops max_loop_param_ops = {
1798 .set = max_loop_param_set_int,
1799 .get = param_get_int,
1800 };
1801
1802 module_param_cb(max_loop, &max_loop_param_ops, &max_loop, 0444);
1803 MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1804 #else
1805 module_param(max_loop, int, 0444);
1806 MODULE_PARM_DESC(max_loop, "Initial number of loop devices");
1807 #endif
1808
1809 module_param(max_part, int, 0444);
1810 MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1811
1812 static int hw_queue_depth = LOOP_DEFAULT_HW_Q_DEPTH;
1813
1814 static int loop_set_hw_queue_depth(const char *s, const struct kernel_param *p)
1815 {
1816 int qd, ret;
1817
1818 ret = kstrtoint(s, 0, &qd);
1819 if (ret < 0)
1820 return ret;
1821 if (qd < 1)
1822 return -EINVAL;
1823 hw_queue_depth = qd;
1824 return 0;
1825 }
1826
1827 static const struct kernel_param_ops loop_hw_qdepth_param_ops = {
1828 .set = loop_set_hw_queue_depth,
1829 .get = param_get_int,
1830 };
1831
1832 device_param_cb(hw_queue_depth, &loop_hw_qdepth_param_ops, &hw_queue_depth, 0444);
1833 MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: " __stringify(LOOP_DEFAULT_HW_Q_DEPTH));
1834
1835 MODULE_DESCRIPTION("Loopback device support");
1836 MODULE_LICENSE("GPL");
1837 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1838
1839 static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
1840 const struct blk_mq_queue_data *bd)
1841 {
1842 struct request *rq = bd->rq;
1843 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
1844 struct loop_device *lo = rq->q->queuedata;
1845
1846 blk_mq_start_request(rq);
1847
1848 if (lo->lo_state != Lo_bound)
1849 return BLK_STS_IOERR;
1850
1851 switch (req_op(rq)) {
1852 case REQ_OP_FLUSH:
1853 case REQ_OP_DISCARD:
1854 case REQ_OP_WRITE_ZEROES:
1855 cmd->use_aio = false;
1856 break;
1857 default:
1858 cmd->use_aio = lo->use_dio;
1859 break;
1860 }
1861
1862 /* always use the first bio's css */
1863 cmd->blkcg_css = NULL;
1864 cmd->memcg_css = NULL;
1865 #ifdef CONFIG_BLK_CGROUP
1866 if (rq->bio) {
1867 cmd->blkcg_css = bio_blkcg_css(rq->bio);
1868 #ifdef CONFIG_MEMCG
1869 if (cmd->blkcg_css) {
1870 cmd->memcg_css =
1871 cgroup_get_e_css(cmd->blkcg_css->cgroup,
1872 &memory_cgrp_subsys);
1873 }
1874 #endif
1875 }
1876 #endif
1877 loop_queue_work(lo, cmd);
1878
1879 return BLK_STS_OK;
1880 }
1881
1882 static void loop_handle_cmd(struct loop_cmd *cmd)
1883 {
1884 struct cgroup_subsys_state *cmd_blkcg_css = cmd->blkcg_css;
1885 struct cgroup_subsys_state *cmd_memcg_css = cmd->memcg_css;
1886 struct request *rq = blk_mq_rq_from_pdu(cmd);
1887 const bool write = op_is_write(req_op(rq));
1888 struct loop_device *lo = rq->q->queuedata;
1889 int ret = 0;
1890 struct mem_cgroup *old_memcg = NULL;
1891 const bool use_aio = cmd->use_aio;
1892
1893 if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) {
1894 ret = -EIO;
1895 goto failed;
1896 }
1897
1898 if (cmd_blkcg_css)
1899 kthread_associate_blkcg(cmd_blkcg_css);
1900 if (cmd_memcg_css)
1901 old_memcg = set_active_memcg(
1902 mem_cgroup_from_css(cmd_memcg_css));
1903
1904 /*
1905 * do_req_filebacked() may call blk_mq_complete_request() synchronously
1906 * or asynchronously if using aio. Hence, do not touch 'cmd' after
1907 * do_req_filebacked() has returned unless we are sure that 'cmd' has
1908 * not yet been completed.
1909 */
1910 ret = do_req_filebacked(lo, rq);
1911
1912 if (cmd_blkcg_css)
1913 kthread_associate_blkcg(NULL);
1914
1915 if (cmd_memcg_css) {
1916 set_active_memcg(old_memcg);
1917 css_put(cmd_memcg_css);
1918 }
1919 failed:
1920 /* complete non-aio request */
1921 if (!use_aio || ret) {
1922 if (ret == -EOPNOTSUPP)
1923 cmd->ret = ret;
1924 else
1925 cmd->ret = ret ? -EIO : 0;
1926 if (likely(!blk_should_fake_timeout(rq->q)))
1927 blk_mq_complete_request(rq);
1928 }
1929 }
1930
1931 static void loop_process_work(struct loop_worker *worker,
1932 struct list_head *cmd_list, struct loop_device *lo)
1933 {
1934 int orig_flags = current->flags;
1935 struct loop_cmd *cmd;
1936
1937 current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO;
1938 spin_lock_irq(&lo->lo_work_lock);
1939 while (!list_empty(cmd_list)) {
1940 cmd = container_of(
1941 cmd_list->next, struct loop_cmd, list_entry);
1942 list_del(cmd_list->next);
1943 spin_unlock_irq(&lo->lo_work_lock);
1944
1945 loop_handle_cmd(cmd);
1946 cond_resched();
1947
1948 spin_lock_irq(&lo->lo_work_lock);
1949 }
1950
1951 /*
1952 * We only add to the idle list if there are no pending cmds
1953 * *and* the worker will not run again which ensures that it
1954 * is safe to free any worker on the idle list
1955 */
1956 if (worker && !work_pending(&worker->work)) {
1957 worker->last_ran_at = jiffies;
1958 list_add_tail(&worker->idle_list, &lo->idle_worker_list);
1959 loop_set_timer(lo);
1960 }
1961 spin_unlock_irq(&lo->lo_work_lock);
1962 current->flags = orig_flags;
1963 }
1964
1965 static void loop_workfn(struct work_struct *work)
1966 {
1967 struct loop_worker *worker =
1968 container_of(work, struct loop_worker, work);
1969 loop_process_work(worker, &worker->cmd_list, worker->lo);
1970 }
1971
1972 static void loop_rootcg_workfn(struct work_struct *work)
1973 {
1974 struct loop_device *lo =
1975 container_of(work, struct loop_device, rootcg_work);
1976 loop_process_work(NULL, &lo->rootcg_cmd_list, lo);
1977 }
1978
1979 static const struct blk_mq_ops loop_mq_ops = {
1980 .queue_rq = loop_queue_rq,
1981 .complete = lo_complete_rq,
1982 };
1983
1984 static int loop_add(int i)
1985 {
1986 struct queue_limits lim = {
1987 /*
1988 * Random number picked from the historic block max_sectors cap.
1989 */
1990 .max_hw_sectors = 2560u,
1991 };
1992 struct loop_device *lo;
1993 struct gendisk *disk;
1994 int err;
1995
1996 err = -ENOMEM;
1997 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1998 if (!lo)
1999 goto out;
2000 lo->worker_tree = RB_ROOT;
2001 INIT_LIST_HEAD(&lo->idle_worker_list);
2002 timer_setup(&lo->timer, loop_free_idle_workers_timer, TIMER_DEFERRABLE);
2003 lo->lo_state = Lo_unbound;
2004
2005 err = mutex_lock_killable(&loop_ctl_mutex);
2006 if (err)
2007 goto out_free_dev;
2008
2009 /* allocate id, if @id >= 0, we're requesting that specific id */
2010 if (i >= 0) {
2011 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
2012 if (err == -ENOSPC)
2013 err = -EEXIST;
2014 } else {
2015 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
2016 }
2017 mutex_unlock(&loop_ctl_mutex);
2018 if (err < 0)
2019 goto out_free_dev;
2020 i = err;
2021
2022 lo->tag_set.ops = &loop_mq_ops;
2023 lo->tag_set.nr_hw_queues = 1;
2024 lo->tag_set.queue_depth = hw_queue_depth;
2025 lo->tag_set.numa_node = NUMA_NO_NODE;
2026 lo->tag_set.cmd_size = sizeof(struct loop_cmd);
2027 lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING |
2028 BLK_MQ_F_NO_SCHED_BY_DEFAULT;
2029 lo->tag_set.driver_data = lo;
2030
2031 err = blk_mq_alloc_tag_set(&lo->tag_set);
2032 if (err)
2033 goto out_free_idr;
2034
2035 disk = lo->lo_disk = blk_mq_alloc_disk(&lo->tag_set, &lim, lo);
2036 if (IS_ERR(disk)) {
2037 err = PTR_ERR(disk);
2038 goto out_cleanup_tags;
2039 }
2040 lo->lo_queue = lo->lo_disk->queue;
2041
2042 /*
2043 * Disable partition scanning by default. The in-kernel partition
2044 * scanning can be requested individually per-device during its
2045 * setup. Userspace can always add and remove partitions from all
2046 * devices. The needed partition minors are allocated from the
2047 * extended minor space, the main loop device numbers will continue
2048 * to match the loop minors, regardless of the number of partitions
2049 * used.
2050 *
2051 * If max_part is given, partition scanning is globally enabled for
2052 * all loop devices. The minors for the main loop devices will be
2053 * multiples of max_part.
2054 *
2055 * Note: Global-for-all-devices, set-only-at-init, read-only module
2056 * parameteters like 'max_loop' and 'max_part' make things needlessly
2057 * complicated, are too static, inflexible and may surprise
2058 * userspace tools. Parameters like this in general should be avoided.
2059 */
2060 if (!part_shift)
2061 set_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
2062 mutex_init(&lo->lo_mutex);
2063 lo->lo_number = i;
2064 spin_lock_init(&lo->lo_lock);
2065 spin_lock_init(&lo->lo_work_lock);
2066 INIT_WORK(&lo->rootcg_work, loop_rootcg_workfn);
2067 INIT_LIST_HEAD(&lo->rootcg_cmd_list);
2068 disk->major = LOOP_MAJOR;
2069 disk->first_minor = i << part_shift;
2070 disk->minors = 1 << part_shift;
2071 disk->fops = &lo_fops;
2072 disk->private_data = lo;
2073 disk->queue = lo->lo_queue;
2074 disk->events = DISK_EVENT_MEDIA_CHANGE;
2075 disk->event_flags = DISK_EVENT_FLAG_UEVENT;
2076 sprintf(disk->disk_name, "loop%d", i);
2077 /* Make this loop device reachable from pathname. */
2078 err = add_disk(disk);
2079 if (err)
2080 goto out_cleanup_disk;
2081
2082 /* Show this loop device. */
2083 mutex_lock(&loop_ctl_mutex);
2084 lo->idr_visible = true;
2085 mutex_unlock(&loop_ctl_mutex);
2086
2087 return i;
2088
2089 out_cleanup_disk:
2090 put_disk(disk);
2091 out_cleanup_tags:
2092 blk_mq_free_tag_set(&lo->tag_set);
2093 out_free_idr:
2094 mutex_lock(&loop_ctl_mutex);
2095 idr_remove(&loop_index_idr, i);
2096 mutex_unlock(&loop_ctl_mutex);
2097 out_free_dev:
2098 kfree(lo);
2099 out:
2100 return err;
2101 }
2102
2103 static void loop_remove(struct loop_device *lo)
2104 {
2105 /* Make this loop device unreachable from pathname. */
2106 del_gendisk(lo->lo_disk);
2107 blk_mq_free_tag_set(&lo->tag_set);
2108
2109 mutex_lock(&loop_ctl_mutex);
2110 idr_remove(&loop_index_idr, lo->lo_number);
2111 mutex_unlock(&loop_ctl_mutex);
2112
2113 put_disk(lo->lo_disk);
2114 }
2115
2116 #ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
2117 static void loop_probe(dev_t dev)
2118 {
2119 int idx = MINOR(dev) >> part_shift;
2120
2121 if (max_loop_specified && max_loop && idx >= max_loop)
2122 return;
2123 loop_add(idx);
2124 }
2125 #else
2126 #define loop_probe NULL
2127 #endif /* !CONFIG_BLOCK_LEGACY_AUTOLOAD */
2128
2129 static int loop_control_remove(int idx)
2130 {
2131 struct loop_device *lo;
2132 int ret;
2133
2134 if (idx < 0) {
2135 pr_warn_once("deleting an unspecified loop device is not supported.\n");
2136 return -EINVAL;
2137 }
2138
2139 /* Hide this loop device for serialization. */
2140 ret = mutex_lock_killable(&loop_ctl_mutex);
2141 if (ret)
2142 return ret;
2143 lo = idr_find(&loop_index_idr, idx);
2144 if (!lo || !lo->idr_visible)
2145 ret = -ENODEV;
2146 else
2147 lo->idr_visible = false;
2148 mutex_unlock(&loop_ctl_mutex);
2149 if (ret)
2150 return ret;
2151
2152 /* Check whether this loop device can be removed. */
2153 ret = mutex_lock_killable(&lo->lo_mutex);
2154 if (ret)
2155 goto mark_visible;
2156 if (lo->lo_state != Lo_unbound || disk_openers(lo->lo_disk) > 0) {
2157 mutex_unlock(&lo->lo_mutex);
2158 ret = -EBUSY;
2159 goto mark_visible;
2160 }
2161 /* Mark this loop device as no more bound, but not quite unbound yet */
2162 lo->lo_state = Lo_deleting;
2163 mutex_unlock(&lo->lo_mutex);
2164
2165 loop_remove(lo);
2166 return 0;
2167
2168 mark_visible:
2169 /* Show this loop device again. */
2170 mutex_lock(&loop_ctl_mutex);
2171 lo->idr_visible = true;
2172 mutex_unlock(&loop_ctl_mutex);
2173 return ret;
2174 }
2175
2176 static int loop_control_get_free(int idx)
2177 {
2178 struct loop_device *lo;
2179 int id, ret;
2180
2181 ret = mutex_lock_killable(&loop_ctl_mutex);
2182 if (ret)
2183 return ret;
2184 idr_for_each_entry(&loop_index_idr, lo, id) {
2185 /* Hitting a race results in creating a new loop device which is harmless. */
2186 if (lo->idr_visible && data_race(lo->lo_state) == Lo_unbound)
2187 goto found;
2188 }
2189 mutex_unlock(&loop_ctl_mutex);
2190 return loop_add(-1);
2191 found:
2192 mutex_unlock(&loop_ctl_mutex);
2193 return id;
2194 }
2195
2196 static long loop_control_ioctl(struct file *file, unsigned int cmd,
2197 unsigned long parm)
2198 {
2199 switch (cmd) {
2200 case LOOP_CTL_ADD:
2201 return loop_add(parm);
2202 case LOOP_CTL_REMOVE:
2203 return loop_control_remove(parm);
2204 case LOOP_CTL_GET_FREE:
2205 return loop_control_get_free(parm);
2206 default:
2207 return -ENOSYS;
2208 }
2209 }
2210
2211 static const struct file_operations loop_ctl_fops = {
2212 .open = nonseekable_open,
2213 .unlocked_ioctl = loop_control_ioctl,
2214 .compat_ioctl = loop_control_ioctl,
2215 .owner = THIS_MODULE,
2216 .llseek = noop_llseek,
2217 };
2218
2219 static struct miscdevice loop_misc = {
2220 .minor = LOOP_CTRL_MINOR,
2221 .name = "loop-control",
2222 .fops = &loop_ctl_fops,
2223 };
2224
2225 MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
2226 MODULE_ALIAS("devname:loop-control");
2227
2228 static int __init loop_init(void)
2229 {
2230 int i;
2231 int err;
2232
2233 part_shift = 0;
2234 if (max_part > 0) {
2235 part_shift = fls(max_part);
2236
2237 /*
2238 * Adjust max_part according to part_shift as it is exported
2239 * to user space so that user can decide correct minor number
2240 * if [s]he want to create more devices.
2241 *
2242 * Note that -1 is required because partition 0 is reserved
2243 * for the whole disk.
2244 */
2245 max_part = (1UL << part_shift) - 1;
2246 }
2247
2248 if ((1UL << part_shift) > DISK_MAX_PARTS) {
2249 err = -EINVAL;
2250 goto err_out;
2251 }
2252
2253 if (max_loop > 1UL << (MINORBITS - part_shift)) {
2254 err = -EINVAL;
2255 goto err_out;
2256 }
2257
2258 err = misc_register(&loop_misc);
2259 if (err < 0)
2260 goto err_out;
2261
2262
2263 if (__register_blkdev(LOOP_MAJOR, "loop", loop_probe)) {
2264 err = -EIO;
2265 goto misc_out;
2266 }
2267
2268 /* pre-create number of devices given by config or max_loop */
2269 for (i = 0; i < max_loop; i++)
2270 loop_add(i);
2271
2272 printk(KERN_INFO "loop: module loaded\n");
2273 return 0;
2274
2275 misc_out:
2276 misc_deregister(&loop_misc);
2277 err_out:
2278 return err;
2279 }
2280
2281 static void __exit loop_exit(void)
2282 {
2283 struct loop_device *lo;
2284 int id;
2285
2286 unregister_blkdev(LOOP_MAJOR, "loop");
2287 misc_deregister(&loop_misc);
2288
2289 /*
2290 * There is no need to use loop_ctl_mutex here, for nobody else can
2291 * access loop_index_idr when this module is unloading (unless forced
2292 * module unloading is requested). If this is not a clean unloading,
2293 * we have no means to avoid kernel crash.
2294 */
2295 idr_for_each_entry(&loop_index_idr, lo, id)
2296 loop_remove(lo);
2297
2298 idr_destroy(&loop_index_idr);
2299 }
2300
2301 module_init(loop_init);
2302 module_exit(loop_exit);
2303
2304 #ifndef MODULE
2305 static int __init max_loop_setup(char *str)
2306 {
2307 max_loop = simple_strtol(str, NULL, 0);
2308 #ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
2309 max_loop_specified = true;
2310 #endif
2311 return 1;
2312 }
2313
2314 __setup("max_loop=", max_loop_setup);
2315 #endif
Kernel DRM miscellaneous fixes and cross-tree changes