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(lock: &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(lock: &lo->lo_mutex); |
135 | if (global) |
136 | mutex_unlock(lock: &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(inode: 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(offset: lo->lo_offset, sizelimit: lo->lo_sizelimit, file); |
166 | } |
167 | |
168 | static void __loop_update_dio(struct loop_device *lo, bool dio) |
169 | { |
170 | struct file *file = lo->lo_backing_file; |
171 | struct address_space *mapping = file->f_mapping; |
172 | struct inode *inode = mapping->host; |
173 | unsigned short sb_bsize = 0; |
174 | unsigned dio_align = 0; |
175 | bool use_dio; |
176 | |
177 | if (inode->i_sb->s_bdev) { |
178 | sb_bsize = bdev_logical_block_size(bdev: inode->i_sb->s_bdev); |
179 | dio_align = sb_bsize - 1; |
180 | } |
181 | |
182 | /* |
183 | * We support direct I/O only if lo_offset is aligned with the |
184 | * logical I/O size of backing device, and the logical block |
185 | * size of loop is bigger than the backing device's. |
186 | * |
187 | * TODO: the above condition may be loosed in the future, and |
188 | * direct I/O may be switched runtime at that time because most |
189 | * of requests in sane applications should be PAGE_SIZE aligned |
190 | */ |
191 | if (dio) { |
192 | if (queue_logical_block_size(q: lo->lo_queue) >= sb_bsize && |
193 | !(lo->lo_offset & dio_align) && |
194 | (file->f_mode & FMODE_CAN_ODIRECT)) |
195 | use_dio = true; |
196 | else |
197 | use_dio = false; |
198 | } else { |
199 | use_dio = false; |
200 | } |
201 | |
202 | if (lo->use_dio == use_dio) |
203 | return; |
204 | |
205 | /* flush dirty pages before changing direct IO */ |
206 | vfs_fsync(file, datasync: 0); |
207 | |
208 | /* |
209 | * The flag of LO_FLAGS_DIRECT_IO is handled similarly with |
210 | * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup |
211 | * will get updated by ioctl(LOOP_GET_STATUS) |
212 | */ |
213 | if (lo->lo_state == Lo_bound) |
214 | blk_mq_freeze_queue(q: lo->lo_queue); |
215 | lo->use_dio = use_dio; |
216 | if (use_dio) { |
217 | blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, q: lo->lo_queue); |
218 | lo->lo_flags |= LO_FLAGS_DIRECT_IO; |
219 | } else { |
220 | blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q: lo->lo_queue); |
221 | lo->lo_flags &= ~LO_FLAGS_DIRECT_IO; |
222 | } |
223 | if (lo->lo_state == Lo_bound) |
224 | blk_mq_unfreeze_queue(q: lo->lo_queue); |
225 | } |
226 | |
227 | /** |
228 | * loop_set_size() - sets device size and notifies userspace |
229 | * @lo: struct loop_device to set the size for |
230 | * @size: new size of the loop device |
231 | * |
232 | * Callers must validate that the size passed into this function fits into |
233 | * a sector_t, eg using loop_validate_size() |
234 | */ |
235 | static void loop_set_size(struct loop_device *lo, loff_t size) |
236 | { |
237 | if (!set_capacity_and_notify(disk: lo->lo_disk, size)) |
238 | kobject_uevent(kobj: &disk_to_dev(lo->lo_disk)->kobj, action: KOBJ_CHANGE); |
239 | } |
240 | |
241 | static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos) |
242 | { |
243 | struct iov_iter i; |
244 | ssize_t bw; |
245 | |
246 | iov_iter_bvec(i: &i, ITER_SOURCE, bvec, nr_segs: 1, count: bvec->bv_len); |
247 | |
248 | file_start_write(file); |
249 | bw = vfs_iter_write(file, iter: &i, ppos, flags: 0); |
250 | file_end_write(file); |
251 | |
252 | if (likely(bw == bvec->bv_len)) |
253 | return 0; |
254 | |
255 | printk_ratelimited(KERN_ERR |
256 | "loop: Write error at byte offset %llu, length %i.\n" , |
257 | (unsigned long long)*ppos, bvec->bv_len); |
258 | if (bw >= 0) |
259 | bw = -EIO; |
260 | return bw; |
261 | } |
262 | |
263 | static int lo_write_simple(struct loop_device *lo, struct request *rq, |
264 | loff_t pos) |
265 | { |
266 | struct bio_vec bvec; |
267 | struct req_iterator iter; |
268 | int ret = 0; |
269 | |
270 | rq_for_each_segment(bvec, rq, iter) { |
271 | ret = lo_write_bvec(file: lo->lo_backing_file, bvec: &bvec, ppos: &pos); |
272 | if (ret < 0) |
273 | break; |
274 | cond_resched(); |
275 | } |
276 | |
277 | return ret; |
278 | } |
279 | |
280 | static int lo_read_simple(struct loop_device *lo, struct request *rq, |
281 | loff_t pos) |
282 | { |
283 | struct bio_vec bvec; |
284 | struct req_iterator iter; |
285 | struct iov_iter i; |
286 | ssize_t len; |
287 | |
288 | rq_for_each_segment(bvec, rq, iter) { |
289 | iov_iter_bvec(i: &i, ITER_DEST, bvec: &bvec, nr_segs: 1, count: bvec.bv_len); |
290 | len = vfs_iter_read(file: lo->lo_backing_file, iter: &i, ppos: &pos, flags: 0); |
291 | if (len < 0) |
292 | return len; |
293 | |
294 | flush_dcache_page(page: bvec.bv_page); |
295 | |
296 | if (len != bvec.bv_len) { |
297 | struct bio *bio; |
298 | |
299 | __rq_for_each_bio(bio, rq) |
300 | zero_fill_bio(bio); |
301 | break; |
302 | } |
303 | cond_resched(); |
304 | } |
305 | |
306 | return 0; |
307 | } |
308 | |
309 | static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos, |
310 | int mode) |
311 | { |
312 | /* |
313 | * We use fallocate to manipulate the space mappings used by the image |
314 | * a.k.a. discard/zerorange. |
315 | */ |
316 | struct file *file = lo->lo_backing_file; |
317 | int ret; |
318 | |
319 | mode |= FALLOC_FL_KEEP_SIZE; |
320 | |
321 | if (!bdev_max_discard_sectors(bdev: lo->lo_device)) |
322 | return -EOPNOTSUPP; |
323 | |
324 | ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq)); |
325 | if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP)) |
326 | return -EIO; |
327 | return ret; |
328 | } |
329 | |
330 | static int lo_req_flush(struct loop_device *lo, struct request *rq) |
331 | { |
332 | int ret = vfs_fsync(file: lo->lo_backing_file, datasync: 0); |
333 | if (unlikely(ret && ret != -EINVAL)) |
334 | ret = -EIO; |
335 | |
336 | return ret; |
337 | } |
338 | |
339 | static void lo_complete_rq(struct request *rq) |
340 | { |
341 | struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); |
342 | blk_status_t ret = BLK_STS_OK; |
343 | |
344 | if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) || |
345 | req_op(req: rq) != REQ_OP_READ) { |
346 | if (cmd->ret < 0) |
347 | ret = errno_to_blk_status(errno: cmd->ret); |
348 | goto end_io; |
349 | } |
350 | |
351 | /* |
352 | * Short READ - if we got some data, advance our request and |
353 | * retry it. If we got no data, end the rest with EIO. |
354 | */ |
355 | if (cmd->ret) { |
356 | blk_update_request(rq, BLK_STS_OK, nr_bytes: cmd->ret); |
357 | cmd->ret = 0; |
358 | blk_mq_requeue_request(rq, kick_requeue_list: true); |
359 | } else { |
360 | if (cmd->use_aio) { |
361 | struct bio *bio = rq->bio; |
362 | |
363 | while (bio) { |
364 | zero_fill_bio(bio); |
365 | bio = bio->bi_next; |
366 | } |
367 | } |
368 | ret = BLK_STS_IOERR; |
369 | end_io: |
370 | blk_mq_end_request(rq, error: ret); |
371 | } |
372 | } |
373 | |
374 | static void lo_rw_aio_do_completion(struct loop_cmd *cmd) |
375 | { |
376 | struct request *rq = blk_mq_rq_from_pdu(pdu: cmd); |
377 | |
378 | if (!atomic_dec_and_test(v: &cmd->ref)) |
379 | return; |
380 | kfree(objp: cmd->bvec); |
381 | cmd->bvec = NULL; |
382 | if (likely(!blk_should_fake_timeout(rq->q))) |
383 | blk_mq_complete_request(rq); |
384 | } |
385 | |
386 | static void lo_rw_aio_complete(struct kiocb *iocb, long ret) |
387 | { |
388 | struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb); |
389 | |
390 | cmd->ret = ret; |
391 | lo_rw_aio_do_completion(cmd); |
392 | } |
393 | |
394 | static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, |
395 | loff_t pos, int rw) |
396 | { |
397 | struct iov_iter iter; |
398 | struct req_iterator rq_iter; |
399 | struct bio_vec *bvec; |
400 | struct request *rq = blk_mq_rq_from_pdu(pdu: cmd); |
401 | struct bio *bio = rq->bio; |
402 | struct file *file = lo->lo_backing_file; |
403 | struct bio_vec tmp; |
404 | unsigned int offset; |
405 | int nr_bvec = 0; |
406 | int ret; |
407 | |
408 | rq_for_each_bvec(tmp, rq, rq_iter) |
409 | nr_bvec++; |
410 | |
411 | if (rq->bio != rq->biotail) { |
412 | |
413 | bvec = kmalloc_array(n: nr_bvec, size: sizeof(struct bio_vec), |
414 | GFP_NOIO); |
415 | if (!bvec) |
416 | return -EIO; |
417 | cmd->bvec = bvec; |
418 | |
419 | /* |
420 | * The bios of the request may be started from the middle of |
421 | * the 'bvec' because of bio splitting, so we can't directly |
422 | * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec |
423 | * API will take care of all details for us. |
424 | */ |
425 | rq_for_each_bvec(tmp, rq, rq_iter) { |
426 | *bvec = tmp; |
427 | bvec++; |
428 | } |
429 | bvec = cmd->bvec; |
430 | offset = 0; |
431 | } else { |
432 | /* |
433 | * Same here, this bio may be started from the middle of the |
434 | * 'bvec' because of bio splitting, so offset from the bvec |
435 | * must be passed to iov iterator |
436 | */ |
437 | offset = bio->bi_iter.bi_bvec_done; |
438 | bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); |
439 | } |
440 | atomic_set(v: &cmd->ref, i: 2); |
441 | |
442 | iov_iter_bvec(i: &iter, direction: rw, bvec, nr_segs: nr_bvec, count: blk_rq_bytes(rq)); |
443 | iter.iov_offset = offset; |
444 | |
445 | cmd->iocb.ki_pos = pos; |
446 | cmd->iocb.ki_filp = file; |
447 | cmd->iocb.ki_complete = lo_rw_aio_complete; |
448 | cmd->iocb.ki_flags = IOCB_DIRECT; |
449 | cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0); |
450 | |
451 | if (rw == ITER_SOURCE) |
452 | ret = call_write_iter(file, kio: &cmd->iocb, iter: &iter); |
453 | else |
454 | ret = call_read_iter(file, kio: &cmd->iocb, iter: &iter); |
455 | |
456 | lo_rw_aio_do_completion(cmd); |
457 | |
458 | if (ret != -EIOCBQUEUED) |
459 | lo_rw_aio_complete(iocb: &cmd->iocb, ret); |
460 | return 0; |
461 | } |
462 | |
463 | static int do_req_filebacked(struct loop_device *lo, struct request *rq) |
464 | { |
465 | struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); |
466 | loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset; |
467 | |
468 | /* |
469 | * lo_write_simple and lo_read_simple should have been covered |
470 | * by io submit style function like lo_rw_aio(), one blocker |
471 | * is that lo_read_simple() need to call flush_dcache_page after |
472 | * the page is written from kernel, and it isn't easy to handle |
473 | * this in io submit style function which submits all segments |
474 | * of the req at one time. And direct read IO doesn't need to |
475 | * run flush_dcache_page(). |
476 | */ |
477 | switch (req_op(req: rq)) { |
478 | case REQ_OP_FLUSH: |
479 | return lo_req_flush(lo, rq); |
480 | case REQ_OP_WRITE_ZEROES: |
481 | /* |
482 | * If the caller doesn't want deallocation, call zeroout to |
483 | * write zeroes the range. Otherwise, punch them out. |
484 | */ |
485 | return lo_fallocate(lo, rq, pos, |
486 | mode: (rq->cmd_flags & REQ_NOUNMAP) ? |
487 | FALLOC_FL_ZERO_RANGE : |
488 | FALLOC_FL_PUNCH_HOLE); |
489 | case REQ_OP_DISCARD: |
490 | return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE); |
491 | case REQ_OP_WRITE: |
492 | if (cmd->use_aio) |
493 | return lo_rw_aio(lo, cmd, pos, ITER_SOURCE); |
494 | else |
495 | return lo_write_simple(lo, rq, pos); |
496 | case REQ_OP_READ: |
497 | if (cmd->use_aio) |
498 | return lo_rw_aio(lo, cmd, pos, ITER_DEST); |
499 | else |
500 | return lo_read_simple(lo, rq, pos); |
501 | default: |
502 | WARN_ON_ONCE(1); |
503 | return -EIO; |
504 | } |
505 | } |
506 | |
507 | static inline void loop_update_dio(struct loop_device *lo) |
508 | { |
509 | __loop_update_dio(lo, dio: (lo->lo_backing_file->f_flags & O_DIRECT) | |
510 | lo->use_dio); |
511 | } |
512 | |
513 | static void loop_reread_partitions(struct loop_device *lo) |
514 | { |
515 | int rc; |
516 | |
517 | mutex_lock(&lo->lo_disk->open_mutex); |
518 | rc = bdev_disk_changed(disk: lo->lo_disk, invalidate: false); |
519 | mutex_unlock(lock: &lo->lo_disk->open_mutex); |
520 | if (rc) |
521 | pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n" , |
522 | __func__, lo->lo_number, lo->lo_file_name, rc); |
523 | } |
524 | |
525 | static inline int is_loop_device(struct file *file) |
526 | { |
527 | struct inode *i = file->f_mapping->host; |
528 | |
529 | return i && S_ISBLK(i->i_mode) && imajor(inode: i) == LOOP_MAJOR; |
530 | } |
531 | |
532 | static int loop_validate_file(struct file *file, struct block_device *bdev) |
533 | { |
534 | struct inode *inode = file->f_mapping->host; |
535 | struct file *f = file; |
536 | |
537 | /* Avoid recursion */ |
538 | while (is_loop_device(file: f)) { |
539 | struct loop_device *l; |
540 | |
541 | lockdep_assert_held(&loop_validate_mutex); |
542 | if (f->f_mapping->host->i_rdev == bdev->bd_dev) |
543 | return -EBADF; |
544 | |
545 | l = I_BDEV(inode: f->f_mapping->host)->bd_disk->private_data; |
546 | if (l->lo_state != Lo_bound) |
547 | return -EINVAL; |
548 | /* Order wrt setting lo->lo_backing_file in loop_configure(). */ |
549 | rmb(); |
550 | f = l->lo_backing_file; |
551 | } |
552 | if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode)) |
553 | return -EINVAL; |
554 | return 0; |
555 | } |
556 | |
557 | /* |
558 | * loop_change_fd switched the backing store of a loopback device to |
559 | * a new file. This is useful for operating system installers to free up |
560 | * the original file and in High Availability environments to switch to |
561 | * an alternative location for the content in case of server meltdown. |
562 | * This can only work if the loop device is used read-only, and if the |
563 | * new backing store is the same size and type as the old backing store. |
564 | */ |
565 | static int loop_change_fd(struct loop_device *lo, struct block_device *bdev, |
566 | unsigned int arg) |
567 | { |
568 | struct file *file = fget(fd: arg); |
569 | struct file *old_file; |
570 | int error; |
571 | bool partscan; |
572 | bool is_loop; |
573 | |
574 | if (!file) |
575 | return -EBADF; |
576 | |
577 | /* suppress uevents while reconfiguring the device */ |
578 | dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), val: 1); |
579 | |
580 | is_loop = is_loop_device(file); |
581 | error = loop_global_lock_killable(lo, global: is_loop); |
582 | if (error) |
583 | goto out_putf; |
584 | error = -ENXIO; |
585 | if (lo->lo_state != Lo_bound) |
586 | goto out_err; |
587 | |
588 | /* the loop device has to be read-only */ |
589 | error = -EINVAL; |
590 | if (!(lo->lo_flags & LO_FLAGS_READ_ONLY)) |
591 | goto out_err; |
592 | |
593 | error = loop_validate_file(file, bdev); |
594 | if (error) |
595 | goto out_err; |
596 | |
597 | old_file = lo->lo_backing_file; |
598 | |
599 | error = -EINVAL; |
600 | |
601 | /* size of the new backing store needs to be the same */ |
602 | if (get_loop_size(lo, file) != get_loop_size(lo, file: old_file)) |
603 | goto out_err; |
604 | |
605 | /* and ... switch */ |
606 | disk_force_media_change(disk: lo->lo_disk); |
607 | blk_mq_freeze_queue(q: lo->lo_queue); |
608 | mapping_set_gfp_mask(m: old_file->f_mapping, mask: lo->old_gfp_mask); |
609 | lo->lo_backing_file = file; |
610 | lo->old_gfp_mask = mapping_gfp_mask(mapping: file->f_mapping); |
611 | mapping_set_gfp_mask(m: file->f_mapping, |
612 | mask: lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); |
613 | loop_update_dio(lo); |
614 | blk_mq_unfreeze_queue(q: lo->lo_queue); |
615 | partscan = lo->lo_flags & LO_FLAGS_PARTSCAN; |
616 | loop_global_unlock(lo, global: is_loop); |
617 | |
618 | /* |
619 | * Flush loop_validate_file() before fput(), for l->lo_backing_file |
620 | * might be pointing at old_file which might be the last reference. |
621 | */ |
622 | if (!is_loop) { |
623 | mutex_lock(&loop_validate_mutex); |
624 | mutex_unlock(lock: &loop_validate_mutex); |
625 | } |
626 | /* |
627 | * We must drop file reference outside of lo_mutex as dropping |
628 | * the file ref can take open_mutex which creates circular locking |
629 | * dependency. |
630 | */ |
631 | fput(old_file); |
632 | if (partscan) |
633 | loop_reread_partitions(lo); |
634 | |
635 | error = 0; |
636 | done: |
637 | /* enable and uncork uevent now that we are done */ |
638 | dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), val: 0); |
639 | return error; |
640 | |
641 | out_err: |
642 | loop_global_unlock(lo, global: is_loop); |
643 | out_putf: |
644 | fput(file); |
645 | goto done; |
646 | } |
647 | |
648 | /* loop sysfs attributes */ |
649 | |
650 | static ssize_t loop_attr_show(struct device *dev, char *page, |
651 | ssize_t (*callback)(struct loop_device *, char *)) |
652 | { |
653 | struct gendisk *disk = dev_to_disk(dev); |
654 | struct loop_device *lo = disk->private_data; |
655 | |
656 | return callback(lo, page); |
657 | } |
658 | |
659 | #define LOOP_ATTR_RO(_name) \ |
660 | static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \ |
661 | static ssize_t loop_attr_do_show_##_name(struct device *d, \ |
662 | struct device_attribute *attr, char *b) \ |
663 | { \ |
664 | return loop_attr_show(d, b, loop_attr_##_name##_show); \ |
665 | } \ |
666 | static struct device_attribute loop_attr_##_name = \ |
667 | __ATTR(_name, 0444, loop_attr_do_show_##_name, NULL); |
668 | |
669 | static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf) |
670 | { |
671 | ssize_t ret; |
672 | char *p = NULL; |
673 | |
674 | spin_lock_irq(lock: &lo->lo_lock); |
675 | if (lo->lo_backing_file) |
676 | p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1); |
677 | spin_unlock_irq(lock: &lo->lo_lock); |
678 | |
679 | if (IS_ERR_OR_NULL(ptr: p)) |
680 | ret = PTR_ERR(ptr: p); |
681 | else { |
682 | ret = strlen(p); |
683 | memmove(buf, p, ret); |
684 | buf[ret++] = '\n'; |
685 | buf[ret] = 0; |
686 | } |
687 | |
688 | return ret; |
689 | } |
690 | |
691 | static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf) |
692 | { |
693 | return sysfs_emit(buf, fmt: "%llu\n" , (unsigned long long)lo->lo_offset); |
694 | } |
695 | |
696 | static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf) |
697 | { |
698 | return sysfs_emit(buf, fmt: "%llu\n" , (unsigned long long)lo->lo_sizelimit); |
699 | } |
700 | |
701 | static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf) |
702 | { |
703 | int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR); |
704 | |
705 | return sysfs_emit(buf, fmt: "%s\n" , autoclear ? "1" : "0" ); |
706 | } |
707 | |
708 | static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf) |
709 | { |
710 | int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN); |
711 | |
712 | return sysfs_emit(buf, fmt: "%s\n" , partscan ? "1" : "0" ); |
713 | } |
714 | |
715 | static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf) |
716 | { |
717 | int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO); |
718 | |
719 | return sysfs_emit(buf, fmt: "%s\n" , dio ? "1" : "0" ); |
720 | } |
721 | |
722 | LOOP_ATTR_RO(backing_file); |
723 | LOOP_ATTR_RO(offset); |
724 | LOOP_ATTR_RO(sizelimit); |
725 | LOOP_ATTR_RO(autoclear); |
726 | LOOP_ATTR_RO(partscan); |
727 | LOOP_ATTR_RO(dio); |
728 | |
729 | static struct attribute *loop_attrs[] = { |
730 | &loop_attr_backing_file.attr, |
731 | &loop_attr_offset.attr, |
732 | &loop_attr_sizelimit.attr, |
733 | &loop_attr_autoclear.attr, |
734 | &loop_attr_partscan.attr, |
735 | &loop_attr_dio.attr, |
736 | NULL, |
737 | }; |
738 | |
739 | static struct attribute_group loop_attribute_group = { |
740 | .name = "loop" , |
741 | .attrs= loop_attrs, |
742 | }; |
743 | |
744 | static void loop_sysfs_init(struct loop_device *lo) |
745 | { |
746 | lo->sysfs_inited = !sysfs_create_group(kobj: &disk_to_dev(lo->lo_disk)->kobj, |
747 | grp: &loop_attribute_group); |
748 | } |
749 | |
750 | static void loop_sysfs_exit(struct loop_device *lo) |
751 | { |
752 | if (lo->sysfs_inited) |
753 | sysfs_remove_group(kobj: &disk_to_dev(lo->lo_disk)->kobj, |
754 | grp: &loop_attribute_group); |
755 | } |
756 | |
757 | static void loop_config_discard(struct loop_device *lo) |
758 | { |
759 | struct file *file = lo->lo_backing_file; |
760 | struct inode *inode = file->f_mapping->host; |
761 | struct request_queue *q = lo->lo_queue; |
762 | u32 granularity, max_discard_sectors; |
763 | |
764 | /* |
765 | * If the backing device is a block device, mirror its zeroing |
766 | * capability. Set the discard sectors to the block device's zeroing |
767 | * capabilities because loop discards result in blkdev_issue_zeroout(), |
768 | * not blkdev_issue_discard(). This maintains consistent behavior with |
769 | * file-backed loop devices: discarded regions read back as zero. |
770 | */ |
771 | if (S_ISBLK(inode->i_mode)) { |
772 | struct request_queue *backingq = bdev_get_queue(bdev: I_BDEV(inode)); |
773 | |
774 | max_discard_sectors = backingq->limits.max_write_zeroes_sectors; |
775 | granularity = bdev_discard_granularity(bdev: I_BDEV(inode)) ?: |
776 | queue_physical_block_size(q: backingq); |
777 | |
778 | /* |
779 | * We use punch hole to reclaim the free space used by the |
780 | * image a.k.a. discard. |
781 | */ |
782 | } else if (!file->f_op->fallocate) { |
783 | max_discard_sectors = 0; |
784 | granularity = 0; |
785 | |
786 | } else { |
787 | struct kstatfs sbuf; |
788 | |
789 | max_discard_sectors = UINT_MAX >> 9; |
790 | if (!vfs_statfs(&file->f_path, &sbuf)) |
791 | granularity = sbuf.f_bsize; |
792 | else |
793 | max_discard_sectors = 0; |
794 | } |
795 | |
796 | if (max_discard_sectors) { |
797 | q->limits.discard_granularity = granularity; |
798 | blk_queue_max_discard_sectors(q, max_discard_sectors); |
799 | blk_queue_max_write_zeroes_sectors(q, max_write_same_sectors: max_discard_sectors); |
800 | } else { |
801 | q->limits.discard_granularity = 0; |
802 | blk_queue_max_discard_sectors(q, max_discard_sectors: 0); |
803 | blk_queue_max_write_zeroes_sectors(q, max_write_same_sectors: 0); |
804 | } |
805 | } |
806 | |
807 | struct loop_worker { |
808 | struct rb_node rb_node; |
809 | struct work_struct work; |
810 | struct list_head cmd_list; |
811 | struct list_head idle_list; |
812 | struct loop_device *lo; |
813 | struct cgroup_subsys_state *blkcg_css; |
814 | unsigned long last_ran_at; |
815 | }; |
816 | |
817 | static void loop_workfn(struct work_struct *work); |
818 | |
819 | #ifdef CONFIG_BLK_CGROUP |
820 | static inline int queue_on_root_worker(struct cgroup_subsys_state *css) |
821 | { |
822 | return !css || css == blkcg_root_css; |
823 | } |
824 | #else |
825 | static inline int queue_on_root_worker(struct cgroup_subsys_state *css) |
826 | { |
827 | return !css; |
828 | } |
829 | #endif |
830 | |
831 | static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd) |
832 | { |
833 | struct rb_node **node, *parent = NULL; |
834 | struct loop_worker *cur_worker, *worker = NULL; |
835 | struct work_struct *work; |
836 | struct list_head *cmd_list; |
837 | |
838 | spin_lock_irq(lock: &lo->lo_work_lock); |
839 | |
840 | if (queue_on_root_worker(css: cmd->blkcg_css)) |
841 | goto queue_work; |
842 | |
843 | node = &lo->worker_tree.rb_node; |
844 | |
845 | while (*node) { |
846 | parent = *node; |
847 | cur_worker = container_of(*node, struct loop_worker, rb_node); |
848 | if (cur_worker->blkcg_css == cmd->blkcg_css) { |
849 | worker = cur_worker; |
850 | break; |
851 | } else if ((long)cur_worker->blkcg_css < (long)cmd->blkcg_css) { |
852 | node = &(*node)->rb_left; |
853 | } else { |
854 | node = &(*node)->rb_right; |
855 | } |
856 | } |
857 | if (worker) |
858 | goto queue_work; |
859 | |
860 | worker = kzalloc(size: sizeof(struct loop_worker), GFP_NOWAIT | __GFP_NOWARN); |
861 | /* |
862 | * In the event we cannot allocate a worker, just queue on the |
863 | * rootcg worker and issue the I/O as the rootcg |
864 | */ |
865 | if (!worker) { |
866 | cmd->blkcg_css = NULL; |
867 | if (cmd->memcg_css) |
868 | css_put(css: cmd->memcg_css); |
869 | cmd->memcg_css = NULL; |
870 | goto queue_work; |
871 | } |
872 | |
873 | worker->blkcg_css = cmd->blkcg_css; |
874 | css_get(css: worker->blkcg_css); |
875 | INIT_WORK(&worker->work, loop_workfn); |
876 | INIT_LIST_HEAD(list: &worker->cmd_list); |
877 | INIT_LIST_HEAD(list: &worker->idle_list); |
878 | worker->lo = lo; |
879 | rb_link_node(node: &worker->rb_node, parent, rb_link: node); |
880 | rb_insert_color(&worker->rb_node, &lo->worker_tree); |
881 | queue_work: |
882 | if (worker) { |
883 | /* |
884 | * We need to remove from the idle list here while |
885 | * holding the lock so that the idle timer doesn't |
886 | * free the worker |
887 | */ |
888 | if (!list_empty(head: &worker->idle_list)) |
889 | list_del_init(entry: &worker->idle_list); |
890 | work = &worker->work; |
891 | cmd_list = &worker->cmd_list; |
892 | } else { |
893 | work = &lo->rootcg_work; |
894 | cmd_list = &lo->rootcg_cmd_list; |
895 | } |
896 | list_add_tail(new: &cmd->list_entry, head: cmd_list); |
897 | queue_work(wq: lo->workqueue, work); |
898 | spin_unlock_irq(lock: &lo->lo_work_lock); |
899 | } |
900 | |
901 | static void loop_set_timer(struct loop_device *lo) |
902 | { |
903 | timer_reduce(timer: &lo->timer, expires: jiffies + LOOP_IDLE_WORKER_TIMEOUT); |
904 | } |
905 | |
906 | static void loop_free_idle_workers(struct loop_device *lo, bool delete_all) |
907 | { |
908 | struct loop_worker *pos, *worker; |
909 | |
910 | spin_lock_irq(lock: &lo->lo_work_lock); |
911 | list_for_each_entry_safe(worker, pos, &lo->idle_worker_list, |
912 | idle_list) { |
913 | if (!delete_all && |
914 | time_is_after_jiffies(worker->last_ran_at + |
915 | LOOP_IDLE_WORKER_TIMEOUT)) |
916 | break; |
917 | list_del(entry: &worker->idle_list); |
918 | rb_erase(&worker->rb_node, &lo->worker_tree); |
919 | css_put(css: worker->blkcg_css); |
920 | kfree(objp: worker); |
921 | } |
922 | if (!list_empty(head: &lo->idle_worker_list)) |
923 | loop_set_timer(lo); |
924 | spin_unlock_irq(lock: &lo->lo_work_lock); |
925 | } |
926 | |
927 | static void loop_free_idle_workers_timer(struct timer_list *timer) |
928 | { |
929 | struct loop_device *lo = container_of(timer, struct loop_device, timer); |
930 | |
931 | return loop_free_idle_workers(lo, delete_all: false); |
932 | } |
933 | |
934 | static void loop_update_rotational(struct loop_device *lo) |
935 | { |
936 | struct file *file = lo->lo_backing_file; |
937 | struct inode *file_inode = file->f_mapping->host; |
938 | struct block_device *file_bdev = file_inode->i_sb->s_bdev; |
939 | struct request_queue *q = lo->lo_queue; |
940 | bool nonrot = true; |
941 | |
942 | /* not all filesystems (e.g. tmpfs) have a sb->s_bdev */ |
943 | if (file_bdev) |
944 | nonrot = bdev_nonrot(bdev: file_bdev); |
945 | |
946 | if (nonrot) |
947 | blk_queue_flag_set(QUEUE_FLAG_NONROT, q); |
948 | else |
949 | blk_queue_flag_clear(QUEUE_FLAG_NONROT, q); |
950 | } |
951 | |
952 | /** |
953 | * loop_set_status_from_info - configure device from loop_info |
954 | * @lo: struct loop_device to configure |
955 | * @info: struct loop_info64 to configure the device with |
956 | * |
957 | * Configures the loop device parameters according to the passed |
958 | * in loop_info64 configuration. |
959 | */ |
960 | static int |
961 | loop_set_status_from_info(struct loop_device *lo, |
962 | const struct loop_info64 *info) |
963 | { |
964 | if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE) |
965 | return -EINVAL; |
966 | |
967 | switch (info->lo_encrypt_type) { |
968 | case LO_CRYPT_NONE: |
969 | break; |
970 | case LO_CRYPT_XOR: |
971 | pr_warn("support for the xor transformation has been removed.\n" ); |
972 | return -EINVAL; |
973 | case LO_CRYPT_CRYPTOAPI: |
974 | pr_warn("support for cryptoloop has been removed. Use dm-crypt instead.\n" ); |
975 | return -EINVAL; |
976 | default: |
977 | return -EINVAL; |
978 | } |
979 | |
980 | /* Avoid assigning overflow values */ |
981 | if (info->lo_offset > LLONG_MAX || info->lo_sizelimit > LLONG_MAX) |
982 | return -EOVERFLOW; |
983 | |
984 | lo->lo_offset = info->lo_offset; |
985 | lo->lo_sizelimit = info->lo_sizelimit; |
986 | |
987 | memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE); |
988 | lo->lo_file_name[LO_NAME_SIZE-1] = 0; |
989 | lo->lo_flags = info->lo_flags; |
990 | return 0; |
991 | } |
992 | |
993 | static int loop_configure(struct loop_device *lo, blk_mode_t mode, |
994 | struct block_device *bdev, |
995 | const struct loop_config *config) |
996 | { |
997 | struct file *file = fget(fd: config->fd); |
998 | struct inode *inode; |
999 | struct address_space *mapping; |
1000 | int error; |
1001 | loff_t size; |
1002 | bool partscan; |
1003 | unsigned short bsize; |
1004 | bool is_loop; |
1005 | |
1006 | if (!file) |
1007 | return -EBADF; |
1008 | is_loop = is_loop_device(file); |
1009 | |
1010 | /* This is safe, since we have a reference from open(). */ |
1011 | __module_get(THIS_MODULE); |
1012 | |
1013 | /* |
1014 | * If we don't hold exclusive handle for the device, upgrade to it |
1015 | * here to avoid changing device under exclusive owner. |
1016 | */ |
1017 | if (!(mode & BLK_OPEN_EXCL)) { |
1018 | error = bd_prepare_to_claim(bdev, holder: loop_configure, NULL); |
1019 | if (error) |
1020 | goto out_putf; |
1021 | } |
1022 | |
1023 | error = loop_global_lock_killable(lo, global: is_loop); |
1024 | if (error) |
1025 | goto out_bdev; |
1026 | |
1027 | error = -EBUSY; |
1028 | if (lo->lo_state != Lo_unbound) |
1029 | goto out_unlock; |
1030 | |
1031 | error = loop_validate_file(file, bdev); |
1032 | if (error) |
1033 | goto out_unlock; |
1034 | |
1035 | mapping = file->f_mapping; |
1036 | inode = mapping->host; |
1037 | |
1038 | if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) { |
1039 | error = -EINVAL; |
1040 | goto out_unlock; |
1041 | } |
1042 | |
1043 | if (config->block_size) { |
1044 | error = blk_validate_block_size(bsize: config->block_size); |
1045 | if (error) |
1046 | goto out_unlock; |
1047 | } |
1048 | |
1049 | error = loop_set_status_from_info(lo, info: &config->info); |
1050 | if (error) |
1051 | goto out_unlock; |
1052 | |
1053 | if (!(file->f_mode & FMODE_WRITE) || !(mode & BLK_OPEN_WRITE) || |
1054 | !file->f_op->write_iter) |
1055 | lo->lo_flags |= LO_FLAGS_READ_ONLY; |
1056 | |
1057 | if (!lo->workqueue) { |
1058 | lo->workqueue = alloc_workqueue(fmt: "loop%d" , |
1059 | flags: WQ_UNBOUND | WQ_FREEZABLE, |
1060 | max_active: 0, lo->lo_number); |
1061 | if (!lo->workqueue) { |
1062 | error = -ENOMEM; |
1063 | goto out_unlock; |
1064 | } |
1065 | } |
1066 | |
1067 | /* suppress uevents while reconfiguring the device */ |
1068 | dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), val: 1); |
1069 | |
1070 | disk_force_media_change(disk: lo->lo_disk); |
1071 | set_disk_ro(disk: lo->lo_disk, read_only: (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0); |
1072 | |
1073 | lo->use_dio = lo->lo_flags & LO_FLAGS_DIRECT_IO; |
1074 | lo->lo_device = bdev; |
1075 | lo->lo_backing_file = file; |
1076 | lo->old_gfp_mask = mapping_gfp_mask(mapping); |
1077 | mapping_set_gfp_mask(m: mapping, mask: lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); |
1078 | |
1079 | if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync) |
1080 | blk_queue_write_cache(q: lo->lo_queue, enabled: true, fua: false); |
1081 | |
1082 | if (config->block_size) |
1083 | bsize = config->block_size; |
1084 | else if ((lo->lo_backing_file->f_flags & O_DIRECT) && inode->i_sb->s_bdev) |
1085 | /* In case of direct I/O, match underlying block size */ |
1086 | bsize = bdev_logical_block_size(bdev: inode->i_sb->s_bdev); |
1087 | else |
1088 | bsize = 512; |
1089 | |
1090 | blk_queue_logical_block_size(lo->lo_queue, bsize); |
1091 | blk_queue_physical_block_size(lo->lo_queue, bsize); |
1092 | blk_queue_io_min(q: lo->lo_queue, min: bsize); |
1093 | |
1094 | loop_config_discard(lo); |
1095 | loop_update_rotational(lo); |
1096 | loop_update_dio(lo); |
1097 | loop_sysfs_init(lo); |
1098 | |
1099 | size = get_loop_size(lo, file); |
1100 | loop_set_size(lo, size); |
1101 | |
1102 | /* Order wrt reading lo_state in loop_validate_file(). */ |
1103 | wmb(); |
1104 | |
1105 | lo->lo_state = Lo_bound; |
1106 | if (part_shift) |
1107 | lo->lo_flags |= LO_FLAGS_PARTSCAN; |
1108 | partscan = lo->lo_flags & LO_FLAGS_PARTSCAN; |
1109 | if (partscan) |
1110 | clear_bit(GD_SUPPRESS_PART_SCAN, addr: &lo->lo_disk->state); |
1111 | |
1112 | /* enable and uncork uevent now that we are done */ |
1113 | dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), val: 0); |
1114 | |
1115 | loop_global_unlock(lo, global: is_loop); |
1116 | if (partscan) |
1117 | loop_reread_partitions(lo); |
1118 | |
1119 | if (!(mode & BLK_OPEN_EXCL)) |
1120 | bd_abort_claiming(bdev, holder: loop_configure); |
1121 | |
1122 | return 0; |
1123 | |
1124 | out_unlock: |
1125 | loop_global_unlock(lo, global: is_loop); |
1126 | out_bdev: |
1127 | if (!(mode & BLK_OPEN_EXCL)) |
1128 | bd_abort_claiming(bdev, holder: loop_configure); |
1129 | out_putf: |
1130 | fput(file); |
1131 | /* This is safe: open() is still holding a reference. */ |
1132 | module_put(THIS_MODULE); |
1133 | return error; |
1134 | } |
1135 | |
1136 | static void __loop_clr_fd(struct loop_device *lo, bool release) |
1137 | { |
1138 | struct file *filp; |
1139 | gfp_t gfp = lo->old_gfp_mask; |
1140 | |
1141 | if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags)) |
1142 | blk_queue_write_cache(q: lo->lo_queue, enabled: false, fua: false); |
1143 | |
1144 | /* |
1145 | * Freeze the request queue when unbinding on a live file descriptor and |
1146 | * thus an open device. When called from ->release we are guaranteed |
1147 | * that there is no I/O in progress already. |
1148 | */ |
1149 | if (!release) |
1150 | blk_mq_freeze_queue(q: lo->lo_queue); |
1151 | |
1152 | spin_lock_irq(lock: &lo->lo_lock); |
1153 | filp = lo->lo_backing_file; |
1154 | lo->lo_backing_file = NULL; |
1155 | spin_unlock_irq(lock: &lo->lo_lock); |
1156 | |
1157 | lo->lo_device = NULL; |
1158 | lo->lo_offset = 0; |
1159 | lo->lo_sizelimit = 0; |
1160 | memset(lo->lo_file_name, 0, LO_NAME_SIZE); |
1161 | blk_queue_logical_block_size(lo->lo_queue, 512); |
1162 | blk_queue_physical_block_size(lo->lo_queue, 512); |
1163 | blk_queue_io_min(q: lo->lo_queue, min: 512); |
1164 | invalidate_disk(disk: lo->lo_disk); |
1165 | loop_sysfs_exit(lo); |
1166 | /* let user-space know about this change */ |
1167 | kobject_uevent(kobj: &disk_to_dev(lo->lo_disk)->kobj, action: KOBJ_CHANGE); |
1168 | mapping_set_gfp_mask(m: filp->f_mapping, mask: gfp); |
1169 | /* This is safe: open() is still holding a reference. */ |
1170 | module_put(THIS_MODULE); |
1171 | if (!release) |
1172 | blk_mq_unfreeze_queue(q: lo->lo_queue); |
1173 | |
1174 | disk_force_media_change(disk: lo->lo_disk); |
1175 | |
1176 | if (lo->lo_flags & LO_FLAGS_PARTSCAN) { |
1177 | int err; |
1178 | |
1179 | /* |
1180 | * open_mutex has been held already in release path, so don't |
1181 | * acquire it if this function is called in such case. |
1182 | * |
1183 | * If the reread partition isn't from release path, lo_refcnt |
1184 | * must be at least one and it can only become zero when the |
1185 | * current holder is released. |
1186 | */ |
1187 | if (!release) |
1188 | mutex_lock(&lo->lo_disk->open_mutex); |
1189 | err = bdev_disk_changed(disk: lo->lo_disk, invalidate: false); |
1190 | if (!release) |
1191 | mutex_unlock(lock: &lo->lo_disk->open_mutex); |
1192 | if (err) |
1193 | pr_warn("%s: partition scan of loop%d failed (rc=%d)\n" , |
1194 | __func__, lo->lo_number, err); |
1195 | /* Device is gone, no point in returning error */ |
1196 | } |
1197 | |
1198 | /* |
1199 | * lo->lo_state is set to Lo_unbound here after above partscan has |
1200 | * finished. There cannot be anybody else entering __loop_clr_fd() as |
1201 | * Lo_rundown state protects us from all the other places trying to |
1202 | * change the 'lo' device. |
1203 | */ |
1204 | lo->lo_flags = 0; |
1205 | if (!part_shift) |
1206 | set_bit(GD_SUPPRESS_PART_SCAN, addr: &lo->lo_disk->state); |
1207 | mutex_lock(&lo->lo_mutex); |
1208 | lo->lo_state = Lo_unbound; |
1209 | mutex_unlock(lock: &lo->lo_mutex); |
1210 | |
1211 | /* |
1212 | * Need not hold lo_mutex to fput backing file. Calling fput holding |
1213 | * lo_mutex triggers a circular lock dependency possibility warning as |
1214 | * fput can take open_mutex which is usually taken before lo_mutex. |
1215 | */ |
1216 | fput(filp); |
1217 | } |
1218 | |
1219 | static int loop_clr_fd(struct loop_device *lo) |
1220 | { |
1221 | int err; |
1222 | |
1223 | /* |
1224 | * Since lo_ioctl() is called without locks held, it is possible that |
1225 | * loop_configure()/loop_change_fd() and loop_clr_fd() run in parallel. |
1226 | * |
1227 | * Therefore, use global lock when setting Lo_rundown state in order to |
1228 | * make sure that loop_validate_file() will fail if the "struct file" |
1229 | * which loop_configure()/loop_change_fd() found via fget() was this |
1230 | * loop device. |
1231 | */ |
1232 | err = loop_global_lock_killable(lo, global: true); |
1233 | if (err) |
1234 | return err; |
1235 | if (lo->lo_state != Lo_bound) { |
1236 | loop_global_unlock(lo, global: true); |
1237 | return -ENXIO; |
1238 | } |
1239 | /* |
1240 | * If we've explicitly asked to tear down the loop device, |
1241 | * and it has an elevated reference count, set it for auto-teardown when |
1242 | * the last reference goes away. This stops $!~#$@ udev from |
1243 | * preventing teardown because it decided that it needs to run blkid on |
1244 | * the loopback device whenever they appear. xfstests is notorious for |
1245 | * failing tests because blkid via udev races with a losetup |
1246 | * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d |
1247 | * command to fail with EBUSY. |
1248 | */ |
1249 | if (disk_openers(disk: lo->lo_disk) > 1) { |
1250 | lo->lo_flags |= LO_FLAGS_AUTOCLEAR; |
1251 | loop_global_unlock(lo, global: true); |
1252 | return 0; |
1253 | } |
1254 | lo->lo_state = Lo_rundown; |
1255 | loop_global_unlock(lo, global: true); |
1256 | |
1257 | __loop_clr_fd(lo, release: false); |
1258 | return 0; |
1259 | } |
1260 | |
1261 | static int |
1262 | loop_set_status(struct loop_device *lo, const struct loop_info64 *info) |
1263 | { |
1264 | int err; |
1265 | int prev_lo_flags; |
1266 | bool partscan = false; |
1267 | bool size_changed = false; |
1268 | |
1269 | err = mutex_lock_killable(&lo->lo_mutex); |
1270 | if (err) |
1271 | return err; |
1272 | if (lo->lo_state != Lo_bound) { |
1273 | err = -ENXIO; |
1274 | goto out_unlock; |
1275 | } |
1276 | |
1277 | if (lo->lo_offset != info->lo_offset || |
1278 | lo->lo_sizelimit != info->lo_sizelimit) { |
1279 | size_changed = true; |
1280 | sync_blockdev(bdev: lo->lo_device); |
1281 | invalidate_bdev(bdev: lo->lo_device); |
1282 | } |
1283 | |
1284 | /* I/O need to be drained during transfer transition */ |
1285 | blk_mq_freeze_queue(q: lo->lo_queue); |
1286 | |
1287 | prev_lo_flags = lo->lo_flags; |
1288 | |
1289 | err = loop_set_status_from_info(lo, info); |
1290 | if (err) |
1291 | goto out_unfreeze; |
1292 | |
1293 | /* Mask out flags that can't be set using LOOP_SET_STATUS. */ |
1294 | lo->lo_flags &= LOOP_SET_STATUS_SETTABLE_FLAGS; |
1295 | /* For those flags, use the previous values instead */ |
1296 | lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_SETTABLE_FLAGS; |
1297 | /* For flags that can't be cleared, use previous values too */ |
1298 | lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_CLEARABLE_FLAGS; |
1299 | |
1300 | if (size_changed) { |
1301 | loff_t new_size = get_size(offset: lo->lo_offset, sizelimit: lo->lo_sizelimit, |
1302 | file: lo->lo_backing_file); |
1303 | loop_set_size(lo, size: new_size); |
1304 | } |
1305 | |
1306 | loop_config_discard(lo); |
1307 | |
1308 | /* update dio if lo_offset or transfer is changed */ |
1309 | __loop_update_dio(lo, dio: lo->use_dio); |
1310 | |
1311 | out_unfreeze: |
1312 | blk_mq_unfreeze_queue(q: lo->lo_queue); |
1313 | |
1314 | if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) && |
1315 | !(prev_lo_flags & LO_FLAGS_PARTSCAN)) { |
1316 | clear_bit(GD_SUPPRESS_PART_SCAN, addr: &lo->lo_disk->state); |
1317 | partscan = true; |
1318 | } |
1319 | out_unlock: |
1320 | mutex_unlock(lock: &lo->lo_mutex); |
1321 | if (partscan) |
1322 | loop_reread_partitions(lo); |
1323 | |
1324 | return err; |
1325 | } |
1326 | |
1327 | static int |
1328 | loop_get_status(struct loop_device *lo, struct loop_info64 *info) |
1329 | { |
1330 | struct path path; |
1331 | struct kstat stat; |
1332 | int ret; |
1333 | |
1334 | ret = mutex_lock_killable(&lo->lo_mutex); |
1335 | if (ret) |
1336 | return ret; |
1337 | if (lo->lo_state != Lo_bound) { |
1338 | mutex_unlock(lock: &lo->lo_mutex); |
1339 | return -ENXIO; |
1340 | } |
1341 | |
1342 | memset(info, 0, sizeof(*info)); |
1343 | info->lo_number = lo->lo_number; |
1344 | info->lo_offset = lo->lo_offset; |
1345 | info->lo_sizelimit = lo->lo_sizelimit; |
1346 | info->lo_flags = lo->lo_flags; |
1347 | memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE); |
1348 | |
1349 | /* Drop lo_mutex while we call into the filesystem. */ |
1350 | path = lo->lo_backing_file->f_path; |
1351 | path_get(&path); |
1352 | mutex_unlock(lock: &lo->lo_mutex); |
1353 | ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT); |
1354 | if (!ret) { |
1355 | info->lo_device = huge_encode_dev(dev: stat.dev); |
1356 | info->lo_inode = stat.ino; |
1357 | info->lo_rdevice = huge_encode_dev(dev: stat.rdev); |
1358 | } |
1359 | path_put(&path); |
1360 | return ret; |
1361 | } |
1362 | |
1363 | static void |
1364 | loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64) |
1365 | { |
1366 | memset(info64, 0, sizeof(*info64)); |
1367 | info64->lo_number = info->lo_number; |
1368 | info64->lo_device = info->lo_device; |
1369 | info64->lo_inode = info->lo_inode; |
1370 | info64->lo_rdevice = info->lo_rdevice; |
1371 | info64->lo_offset = info->lo_offset; |
1372 | info64->lo_sizelimit = 0; |
1373 | info64->lo_flags = info->lo_flags; |
1374 | memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE); |
1375 | } |
1376 | |
1377 | static int |
1378 | loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info) |
1379 | { |
1380 | memset(info, 0, sizeof(*info)); |
1381 | info->lo_number = info64->lo_number; |
1382 | info->lo_device = info64->lo_device; |
1383 | info->lo_inode = info64->lo_inode; |
1384 | info->lo_rdevice = info64->lo_rdevice; |
1385 | info->lo_offset = info64->lo_offset; |
1386 | info->lo_flags = info64->lo_flags; |
1387 | memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE); |
1388 | |
1389 | /* error in case values were truncated */ |
1390 | if (info->lo_device != info64->lo_device || |
1391 | info->lo_rdevice != info64->lo_rdevice || |
1392 | info->lo_inode != info64->lo_inode || |
1393 | info->lo_offset != info64->lo_offset) |
1394 | return -EOVERFLOW; |
1395 | |
1396 | return 0; |
1397 | } |
1398 | |
1399 | static int |
1400 | loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg) |
1401 | { |
1402 | struct loop_info info; |
1403 | struct loop_info64 info64; |
1404 | |
1405 | if (copy_from_user(to: &info, from: arg, n: sizeof (struct loop_info))) |
1406 | return -EFAULT; |
1407 | loop_info64_from_old(info: &info, info64: &info64); |
1408 | return loop_set_status(lo, info: &info64); |
1409 | } |
1410 | |
1411 | static int |
1412 | loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg) |
1413 | { |
1414 | struct loop_info64 info64; |
1415 | |
1416 | if (copy_from_user(to: &info64, from: arg, n: sizeof (struct loop_info64))) |
1417 | return -EFAULT; |
1418 | return loop_set_status(lo, info: &info64); |
1419 | } |
1420 | |
1421 | static int |
1422 | loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) { |
1423 | struct loop_info info; |
1424 | struct loop_info64 info64; |
1425 | int err; |
1426 | |
1427 | if (!arg) |
1428 | return -EINVAL; |
1429 | err = loop_get_status(lo, info: &info64); |
1430 | if (!err) |
1431 | err = loop_info64_to_old(info64: &info64, info: &info); |
1432 | if (!err && copy_to_user(to: arg, from: &info, n: sizeof(info))) |
1433 | err = -EFAULT; |
1434 | |
1435 | return err; |
1436 | } |
1437 | |
1438 | static int |
1439 | loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) { |
1440 | struct loop_info64 info64; |
1441 | int err; |
1442 | |
1443 | if (!arg) |
1444 | return -EINVAL; |
1445 | err = loop_get_status(lo, info: &info64); |
1446 | if (!err && copy_to_user(to: arg, from: &info64, n: sizeof(info64))) |
1447 | err = -EFAULT; |
1448 | |
1449 | return err; |
1450 | } |
1451 | |
1452 | static int loop_set_capacity(struct loop_device *lo) |
1453 | { |
1454 | loff_t size; |
1455 | |
1456 | if (unlikely(lo->lo_state != Lo_bound)) |
1457 | return -ENXIO; |
1458 | |
1459 | size = get_loop_size(lo, file: lo->lo_backing_file); |
1460 | loop_set_size(lo, size); |
1461 | |
1462 | return 0; |
1463 | } |
1464 | |
1465 | static int loop_set_dio(struct loop_device *lo, unsigned long arg) |
1466 | { |
1467 | int error = -ENXIO; |
1468 | if (lo->lo_state != Lo_bound) |
1469 | goto out; |
1470 | |
1471 | __loop_update_dio(lo, dio: !!arg); |
1472 | if (lo->use_dio == !!arg) |
1473 | return 0; |
1474 | error = -EINVAL; |
1475 | out: |
1476 | return error; |
1477 | } |
1478 | |
1479 | static int loop_set_block_size(struct loop_device *lo, unsigned long arg) |
1480 | { |
1481 | int err = 0; |
1482 | |
1483 | if (lo->lo_state != Lo_bound) |
1484 | return -ENXIO; |
1485 | |
1486 | err = blk_validate_block_size(bsize: arg); |
1487 | if (err) |
1488 | return err; |
1489 | |
1490 | if (lo->lo_queue->limits.logical_block_size == arg) |
1491 | return 0; |
1492 | |
1493 | sync_blockdev(bdev: lo->lo_device); |
1494 | invalidate_bdev(bdev: lo->lo_device); |
1495 | |
1496 | blk_mq_freeze_queue(q: lo->lo_queue); |
1497 | blk_queue_logical_block_size(lo->lo_queue, arg); |
1498 | blk_queue_physical_block_size(lo->lo_queue, arg); |
1499 | blk_queue_io_min(q: lo->lo_queue, min: arg); |
1500 | loop_update_dio(lo); |
1501 | blk_mq_unfreeze_queue(q: lo->lo_queue); |
1502 | |
1503 | return err; |
1504 | } |
1505 | |
1506 | static int lo_simple_ioctl(struct loop_device *lo, unsigned int cmd, |
1507 | unsigned long arg) |
1508 | { |
1509 | int err; |
1510 | |
1511 | err = mutex_lock_killable(&lo->lo_mutex); |
1512 | if (err) |
1513 | return err; |
1514 | switch (cmd) { |
1515 | case LOOP_SET_CAPACITY: |
1516 | err = loop_set_capacity(lo); |
1517 | break; |
1518 | case LOOP_SET_DIRECT_IO: |
1519 | err = loop_set_dio(lo, arg); |
1520 | break; |
1521 | case LOOP_SET_BLOCK_SIZE: |
1522 | err = loop_set_block_size(lo, arg); |
1523 | break; |
1524 | default: |
1525 | err = -EINVAL; |
1526 | } |
1527 | mutex_unlock(lock: &lo->lo_mutex); |
1528 | return err; |
1529 | } |
1530 | |
1531 | static int lo_ioctl(struct block_device *bdev, blk_mode_t mode, |
1532 | unsigned int cmd, unsigned long arg) |
1533 | { |
1534 | struct loop_device *lo = bdev->bd_disk->private_data; |
1535 | void __user *argp = (void __user *) arg; |
1536 | int err; |
1537 | |
1538 | switch (cmd) { |
1539 | case LOOP_SET_FD: { |
1540 | /* |
1541 | * Legacy case - pass in a zeroed out struct loop_config with |
1542 | * only the file descriptor set , which corresponds with the |
1543 | * default parameters we'd have used otherwise. |
1544 | */ |
1545 | struct loop_config config; |
1546 | |
1547 | memset(&config, 0, sizeof(config)); |
1548 | config.fd = arg; |
1549 | |
1550 | return loop_configure(lo, mode, bdev, config: &config); |
1551 | } |
1552 | case LOOP_CONFIGURE: { |
1553 | struct loop_config config; |
1554 | |
1555 | if (copy_from_user(to: &config, from: argp, n: sizeof(config))) |
1556 | return -EFAULT; |
1557 | |
1558 | return loop_configure(lo, mode, bdev, config: &config); |
1559 | } |
1560 | case LOOP_CHANGE_FD: |
1561 | return loop_change_fd(lo, bdev, arg); |
1562 | case LOOP_CLR_FD: |
1563 | return loop_clr_fd(lo); |
1564 | case LOOP_SET_STATUS: |
1565 | err = -EPERM; |
1566 | if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN)) |
1567 | err = loop_set_status_old(lo, arg: argp); |
1568 | break; |
1569 | case LOOP_GET_STATUS: |
1570 | return loop_get_status_old(lo, arg: argp); |
1571 | case LOOP_SET_STATUS64: |
1572 | err = -EPERM; |
1573 | if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN)) |
1574 | err = loop_set_status64(lo, arg: argp); |
1575 | break; |
1576 | case LOOP_GET_STATUS64: |
1577 | return loop_get_status64(lo, arg: argp); |
1578 | case LOOP_SET_CAPACITY: |
1579 | case LOOP_SET_DIRECT_IO: |
1580 | case LOOP_SET_BLOCK_SIZE: |
1581 | if (!(mode & BLK_OPEN_WRITE) && !capable(CAP_SYS_ADMIN)) |
1582 | return -EPERM; |
1583 | fallthrough; |
1584 | default: |
1585 | err = lo_simple_ioctl(lo, cmd, arg); |
1586 | break; |
1587 | } |
1588 | |
1589 | return err; |
1590 | } |
1591 | |
1592 | #ifdef CONFIG_COMPAT |
1593 | struct compat_loop_info { |
1594 | compat_int_t lo_number; /* ioctl r/o */ |
1595 | compat_dev_t lo_device; /* ioctl r/o */ |
1596 | compat_ulong_t lo_inode; /* ioctl r/o */ |
1597 | compat_dev_t lo_rdevice; /* ioctl r/o */ |
1598 | compat_int_t lo_offset; |
1599 | compat_int_t lo_encrypt_type; /* obsolete, ignored */ |
1600 | compat_int_t lo_encrypt_key_size; /* ioctl w/o */ |
1601 | compat_int_t lo_flags; /* ioctl r/o */ |
1602 | char lo_name[LO_NAME_SIZE]; |
1603 | unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */ |
1604 | compat_ulong_t lo_init[2]; |
1605 | char reserved[4]; |
1606 | }; |
1607 | |
1608 | /* |
1609 | * Transfer 32-bit compatibility structure in userspace to 64-bit loop info |
1610 | * - noinlined to reduce stack space usage in main part of driver |
1611 | */ |
1612 | static noinline int |
1613 | loop_info64_from_compat(const struct compat_loop_info __user *arg, |
1614 | struct loop_info64 *info64) |
1615 | { |
1616 | struct compat_loop_info info; |
1617 | |
1618 | if (copy_from_user(to: &info, from: arg, n: sizeof(info))) |
1619 | return -EFAULT; |
1620 | |
1621 | memset(info64, 0, sizeof(*info64)); |
1622 | info64->lo_number = info.lo_number; |
1623 | info64->lo_device = info.lo_device; |
1624 | info64->lo_inode = info.lo_inode; |
1625 | info64->lo_rdevice = info.lo_rdevice; |
1626 | info64->lo_offset = info.lo_offset; |
1627 | info64->lo_sizelimit = 0; |
1628 | info64->lo_flags = info.lo_flags; |
1629 | memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE); |
1630 | return 0; |
1631 | } |
1632 | |
1633 | /* |
1634 | * Transfer 64-bit loop info to 32-bit compatibility structure in userspace |
1635 | * - noinlined to reduce stack space usage in main part of driver |
1636 | */ |
1637 | static noinline int |
1638 | loop_info64_to_compat(const struct loop_info64 *info64, |
1639 | struct compat_loop_info __user *arg) |
1640 | { |
1641 | struct compat_loop_info info; |
1642 | |
1643 | memset(&info, 0, sizeof(info)); |
1644 | info.lo_number = info64->lo_number; |
1645 | info.lo_device = info64->lo_device; |
1646 | info.lo_inode = info64->lo_inode; |
1647 | info.lo_rdevice = info64->lo_rdevice; |
1648 | info.lo_offset = info64->lo_offset; |
1649 | info.lo_flags = info64->lo_flags; |
1650 | memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE); |
1651 | |
1652 | /* error in case values were truncated */ |
1653 | if (info.lo_device != info64->lo_device || |
1654 | info.lo_rdevice != info64->lo_rdevice || |
1655 | info.lo_inode != info64->lo_inode || |
1656 | info.lo_offset != info64->lo_offset) |
1657 | return -EOVERFLOW; |
1658 | |
1659 | if (copy_to_user(to: arg, from: &info, n: sizeof(info))) |
1660 | return -EFAULT; |
1661 | return 0; |
1662 | } |
1663 | |
1664 | static int |
1665 | loop_set_status_compat(struct loop_device *lo, |
1666 | const struct compat_loop_info __user *arg) |
1667 | { |
1668 | struct loop_info64 info64; |
1669 | int ret; |
1670 | |
1671 | ret = loop_info64_from_compat(arg, info64: &info64); |
1672 | if (ret < 0) |
1673 | return ret; |
1674 | return loop_set_status(lo, info: &info64); |
1675 | } |
1676 | |
1677 | static int |
1678 | loop_get_status_compat(struct loop_device *lo, |
1679 | struct compat_loop_info __user *arg) |
1680 | { |
1681 | struct loop_info64 info64; |
1682 | int err; |
1683 | |
1684 | if (!arg) |
1685 | return -EINVAL; |
1686 | err = loop_get_status(lo, info: &info64); |
1687 | if (!err) |
1688 | err = loop_info64_to_compat(info64: &info64, arg); |
1689 | return err; |
1690 | } |
1691 | |
1692 | static int lo_compat_ioctl(struct block_device *bdev, blk_mode_t mode, |
1693 | unsigned int cmd, unsigned long arg) |
1694 | { |
1695 | struct loop_device *lo = bdev->bd_disk->private_data; |
1696 | int err; |
1697 | |
1698 | switch(cmd) { |
1699 | case LOOP_SET_STATUS: |
1700 | err = loop_set_status_compat(lo, |
1701 | arg: (const struct compat_loop_info __user *)arg); |
1702 | break; |
1703 | case LOOP_GET_STATUS: |
1704 | err = loop_get_status_compat(lo, |
1705 | arg: (struct compat_loop_info __user *)arg); |
1706 | break; |
1707 | case LOOP_SET_CAPACITY: |
1708 | case LOOP_CLR_FD: |
1709 | case LOOP_GET_STATUS64: |
1710 | case LOOP_SET_STATUS64: |
1711 | case LOOP_CONFIGURE: |
1712 | arg = (unsigned long) compat_ptr(uptr: arg); |
1713 | fallthrough; |
1714 | case LOOP_SET_FD: |
1715 | case LOOP_CHANGE_FD: |
1716 | case LOOP_SET_BLOCK_SIZE: |
1717 | case LOOP_SET_DIRECT_IO: |
1718 | err = lo_ioctl(bdev, mode, cmd, arg); |
1719 | break; |
1720 | default: |
1721 | err = -ENOIOCTLCMD; |
1722 | break; |
1723 | } |
1724 | return err; |
1725 | } |
1726 | #endif |
1727 | |
1728 | static void lo_release(struct gendisk *disk) |
1729 | { |
1730 | struct loop_device *lo = disk->private_data; |
1731 | |
1732 | if (disk_openers(disk) > 0) |
1733 | return; |
1734 | |
1735 | mutex_lock(&lo->lo_mutex); |
1736 | if (lo->lo_state == Lo_bound && (lo->lo_flags & LO_FLAGS_AUTOCLEAR)) { |
1737 | lo->lo_state = Lo_rundown; |
1738 | mutex_unlock(lock: &lo->lo_mutex); |
1739 | /* |
1740 | * In autoclear mode, stop the loop thread |
1741 | * and remove configuration after last close. |
1742 | */ |
1743 | __loop_clr_fd(lo, release: true); |
1744 | return; |
1745 | } |
1746 | mutex_unlock(lock: &lo->lo_mutex); |
1747 | } |
1748 | |
1749 | static void lo_free_disk(struct gendisk *disk) |
1750 | { |
1751 | struct loop_device *lo = disk->private_data; |
1752 | |
1753 | if (lo->workqueue) |
1754 | destroy_workqueue(wq: lo->workqueue); |
1755 | loop_free_idle_workers(lo, delete_all: true); |
1756 | timer_shutdown_sync(timer: &lo->timer); |
1757 | mutex_destroy(lock: &lo->lo_mutex); |
1758 | kfree(objp: lo); |
1759 | } |
1760 | |
1761 | static const struct block_device_operations lo_fops = { |
1762 | .owner = THIS_MODULE, |
1763 | .release = lo_release, |
1764 | .ioctl = lo_ioctl, |
1765 | #ifdef CONFIG_COMPAT |
1766 | .compat_ioctl = lo_compat_ioctl, |
1767 | #endif |
1768 | .free_disk = lo_free_disk, |
1769 | }; |
1770 | |
1771 | /* |
1772 | * And now the modules code and kernel interface. |
1773 | */ |
1774 | |
1775 | /* |
1776 | * If max_loop is specified, create that many devices upfront. |
1777 | * This also becomes a hard limit. If max_loop is not specified, |
1778 | * the default isn't a hard limit (as before commit 85c50197716c |
1779 | * changed the default value from 0 for max_loop=0 reasons), just |
1780 | * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module |
1781 | * init time. Loop devices can be requested on-demand with the |
1782 | * /dev/loop-control interface, or be instantiated by accessing |
1783 | * a 'dead' device node. |
1784 | */ |
1785 | static int max_loop = CONFIG_BLK_DEV_LOOP_MIN_COUNT; |
1786 | |
1787 | #ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD |
1788 | static bool max_loop_specified; |
1789 | |
1790 | static int max_loop_param_set_int(const char *val, |
1791 | const struct kernel_param *kp) |
1792 | { |
1793 | int ret; |
1794 | |
1795 | ret = param_set_int(val, kp); |
1796 | if (ret < 0) |
1797 | return ret; |
1798 | |
1799 | max_loop_specified = true; |
1800 | return 0; |
1801 | } |
1802 | |
1803 | static const struct kernel_param_ops max_loop_param_ops = { |
1804 | .set = max_loop_param_set_int, |
1805 | .get = param_get_int, |
1806 | }; |
1807 | |
1808 | module_param_cb(max_loop, &max_loop_param_ops, &max_loop, 0444); |
1809 | MODULE_PARM_DESC(max_loop, "Maximum number of loop devices" ); |
1810 | #else |
1811 | module_param(max_loop, int, 0444); |
1812 | MODULE_PARM_DESC(max_loop, "Initial number of loop devices" ); |
1813 | #endif |
1814 | |
1815 | module_param(max_part, int, 0444); |
1816 | MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device" ); |
1817 | |
1818 | static int hw_queue_depth = LOOP_DEFAULT_HW_Q_DEPTH; |
1819 | |
1820 | static int loop_set_hw_queue_depth(const char *s, const struct kernel_param *p) |
1821 | { |
1822 | int qd, ret; |
1823 | |
1824 | ret = kstrtoint(s, base: 0, res: &qd); |
1825 | if (ret < 0) |
1826 | return ret; |
1827 | if (qd < 1) |
1828 | return -EINVAL; |
1829 | hw_queue_depth = qd; |
1830 | return 0; |
1831 | } |
1832 | |
1833 | static const struct kernel_param_ops loop_hw_qdepth_param_ops = { |
1834 | .set = loop_set_hw_queue_depth, |
1835 | .get = param_get_int, |
1836 | }; |
1837 | |
1838 | device_param_cb(hw_queue_depth, &loop_hw_qdepth_param_ops, &hw_queue_depth, 0444); |
1839 | MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: " __stringify(LOOP_DEFAULT_HW_Q_DEPTH)); |
1840 | |
1841 | MODULE_LICENSE("GPL" ); |
1842 | MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR); |
1843 | |
1844 | static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx, |
1845 | const struct blk_mq_queue_data *bd) |
1846 | { |
1847 | struct request *rq = bd->rq; |
1848 | struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); |
1849 | struct loop_device *lo = rq->q->queuedata; |
1850 | |
1851 | blk_mq_start_request(rq); |
1852 | |
1853 | if (lo->lo_state != Lo_bound) |
1854 | return BLK_STS_IOERR; |
1855 | |
1856 | switch (req_op(req: rq)) { |
1857 | case REQ_OP_FLUSH: |
1858 | case REQ_OP_DISCARD: |
1859 | case REQ_OP_WRITE_ZEROES: |
1860 | cmd->use_aio = false; |
1861 | break; |
1862 | default: |
1863 | cmd->use_aio = lo->use_dio; |
1864 | break; |
1865 | } |
1866 | |
1867 | /* always use the first bio's css */ |
1868 | cmd->blkcg_css = NULL; |
1869 | cmd->memcg_css = NULL; |
1870 | #ifdef CONFIG_BLK_CGROUP |
1871 | if (rq->bio) { |
1872 | cmd->blkcg_css = bio_blkcg_css(bio: rq->bio); |
1873 | #ifdef CONFIG_MEMCG |
1874 | if (cmd->blkcg_css) { |
1875 | cmd->memcg_css = |
1876 | cgroup_get_e_css(cgroup: cmd->blkcg_css->cgroup, |
1877 | ss: &memory_cgrp_subsys); |
1878 | } |
1879 | #endif |
1880 | } |
1881 | #endif |
1882 | loop_queue_work(lo, cmd); |
1883 | |
1884 | return BLK_STS_OK; |
1885 | } |
1886 | |
1887 | static void loop_handle_cmd(struct loop_cmd *cmd) |
1888 | { |
1889 | struct cgroup_subsys_state *cmd_blkcg_css = cmd->blkcg_css; |
1890 | struct cgroup_subsys_state *cmd_memcg_css = cmd->memcg_css; |
1891 | struct request *rq = blk_mq_rq_from_pdu(pdu: cmd); |
1892 | const bool write = op_is_write(op: req_op(req: rq)); |
1893 | struct loop_device *lo = rq->q->queuedata; |
1894 | int ret = 0; |
1895 | struct mem_cgroup *old_memcg = NULL; |
1896 | const bool use_aio = cmd->use_aio; |
1897 | |
1898 | if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) { |
1899 | ret = -EIO; |
1900 | goto failed; |
1901 | } |
1902 | |
1903 | if (cmd_blkcg_css) |
1904 | kthread_associate_blkcg(css: cmd_blkcg_css); |
1905 | if (cmd_memcg_css) |
1906 | old_memcg = set_active_memcg( |
1907 | mem_cgroup_from_css(css: cmd_memcg_css)); |
1908 | |
1909 | /* |
1910 | * do_req_filebacked() may call blk_mq_complete_request() synchronously |
1911 | * or asynchronously if using aio. Hence, do not touch 'cmd' after |
1912 | * do_req_filebacked() has returned unless we are sure that 'cmd' has |
1913 | * not yet been completed. |
1914 | */ |
1915 | ret = do_req_filebacked(lo, rq); |
1916 | |
1917 | if (cmd_blkcg_css) |
1918 | kthread_associate_blkcg(NULL); |
1919 | |
1920 | if (cmd_memcg_css) { |
1921 | set_active_memcg(old_memcg); |
1922 | css_put(css: cmd_memcg_css); |
1923 | } |
1924 | failed: |
1925 | /* complete non-aio request */ |
1926 | if (!use_aio || ret) { |
1927 | if (ret == -EOPNOTSUPP) |
1928 | cmd->ret = ret; |
1929 | else |
1930 | cmd->ret = ret ? -EIO : 0; |
1931 | if (likely(!blk_should_fake_timeout(rq->q))) |
1932 | blk_mq_complete_request(rq); |
1933 | } |
1934 | } |
1935 | |
1936 | static void loop_process_work(struct loop_worker *worker, |
1937 | struct list_head *cmd_list, struct loop_device *lo) |
1938 | { |
1939 | int orig_flags = current->flags; |
1940 | struct loop_cmd *cmd; |
1941 | |
1942 | current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO; |
1943 | spin_lock_irq(lock: &lo->lo_work_lock); |
1944 | while (!list_empty(head: cmd_list)) { |
1945 | cmd = container_of( |
1946 | cmd_list->next, struct loop_cmd, list_entry); |
1947 | list_del(entry: cmd_list->next); |
1948 | spin_unlock_irq(lock: &lo->lo_work_lock); |
1949 | |
1950 | loop_handle_cmd(cmd); |
1951 | cond_resched(); |
1952 | |
1953 | spin_lock_irq(lock: &lo->lo_work_lock); |
1954 | } |
1955 | |
1956 | /* |
1957 | * We only add to the idle list if there are no pending cmds |
1958 | * *and* the worker will not run again which ensures that it |
1959 | * is safe to free any worker on the idle list |
1960 | */ |
1961 | if (worker && !work_pending(&worker->work)) { |
1962 | worker->last_ran_at = jiffies; |
1963 | list_add_tail(new: &worker->idle_list, head: &lo->idle_worker_list); |
1964 | loop_set_timer(lo); |
1965 | } |
1966 | spin_unlock_irq(lock: &lo->lo_work_lock); |
1967 | current->flags = orig_flags; |
1968 | } |
1969 | |
1970 | static void loop_workfn(struct work_struct *work) |
1971 | { |
1972 | struct loop_worker *worker = |
1973 | container_of(work, struct loop_worker, work); |
1974 | loop_process_work(worker, cmd_list: &worker->cmd_list, lo: worker->lo); |
1975 | } |
1976 | |
1977 | static void loop_rootcg_workfn(struct work_struct *work) |
1978 | { |
1979 | struct loop_device *lo = |
1980 | container_of(work, struct loop_device, rootcg_work); |
1981 | loop_process_work(NULL, cmd_list: &lo->rootcg_cmd_list, lo); |
1982 | } |
1983 | |
1984 | static const struct blk_mq_ops loop_mq_ops = { |
1985 | .queue_rq = loop_queue_rq, |
1986 | .complete = lo_complete_rq, |
1987 | }; |
1988 | |
1989 | static int loop_add(int i) |
1990 | { |
1991 | struct loop_device *lo; |
1992 | struct gendisk *disk; |
1993 | int err; |
1994 | |
1995 | err = -ENOMEM; |
1996 | lo = kzalloc(size: sizeof(*lo), GFP_KERNEL); |
1997 | if (!lo) |
1998 | goto out; |
1999 | lo->worker_tree = RB_ROOT; |
2000 | INIT_LIST_HEAD(list: &lo->idle_worker_list); |
2001 | timer_setup(&lo->timer, loop_free_idle_workers_timer, TIMER_DEFERRABLE); |
2002 | lo->lo_state = Lo_unbound; |
2003 | |
2004 | err = mutex_lock_killable(&loop_ctl_mutex); |
2005 | if (err) |
2006 | goto out_free_dev; |
2007 | |
2008 | /* allocate id, if @id >= 0, we're requesting that specific id */ |
2009 | if (i >= 0) { |
2010 | err = idr_alloc(&loop_index_idr, ptr: lo, start: i, end: i + 1, GFP_KERNEL); |
2011 | if (err == -ENOSPC) |
2012 | err = -EEXIST; |
2013 | } else { |
2014 | err = idr_alloc(&loop_index_idr, ptr: lo, start: 0, end: 0, GFP_KERNEL); |
2015 | } |
2016 | mutex_unlock(lock: &loop_ctl_mutex); |
2017 | if (err < 0) |
2018 | goto out_free_dev; |
2019 | i = err; |
2020 | |
2021 | lo->tag_set.ops = &loop_mq_ops; |
2022 | lo->tag_set.nr_hw_queues = 1; |
2023 | lo->tag_set.queue_depth = hw_queue_depth; |
2024 | lo->tag_set.numa_node = NUMA_NO_NODE; |
2025 | lo->tag_set.cmd_size = sizeof(struct loop_cmd); |
2026 | lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING | |
2027 | BLK_MQ_F_NO_SCHED_BY_DEFAULT; |
2028 | lo->tag_set.driver_data = lo; |
2029 | |
2030 | err = blk_mq_alloc_tag_set(set: &lo->tag_set); |
2031 | if (err) |
2032 | goto out_free_idr; |
2033 | |
2034 | disk = lo->lo_disk = blk_mq_alloc_disk(&lo->tag_set, lo); |
2035 | if (IS_ERR(ptr: disk)) { |
2036 | err = PTR_ERR(ptr: disk); |
2037 | goto out_cleanup_tags; |
2038 | } |
2039 | lo->lo_queue = lo->lo_disk->queue; |
2040 | |
2041 | blk_queue_max_hw_sectors(lo->lo_queue, BLK_DEF_MAX_SECTORS); |
2042 | |
2043 | /* |
2044 | * By default, we do buffer IO, so it doesn't make sense to enable |
2045 | * merge because the I/O submitted to backing file is handled page by |
2046 | * page. For directio mode, merge does help to dispatch bigger request |
2047 | * to underlayer disk. We will enable merge once directio is enabled. |
2048 | */ |
2049 | blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q: lo->lo_queue); |
2050 | |
2051 | /* |
2052 | * Disable partition scanning by default. The in-kernel partition |
2053 | * scanning can be requested individually per-device during its |
2054 | * setup. Userspace can always add and remove partitions from all |
2055 | * devices. The needed partition minors are allocated from the |
2056 | * extended minor space, the main loop device numbers will continue |
2057 | * to match the loop minors, regardless of the number of partitions |
2058 | * used. |
2059 | * |
2060 | * If max_part is given, partition scanning is globally enabled for |
2061 | * all loop devices. The minors for the main loop devices will be |
2062 | * multiples of max_part. |
2063 | * |
2064 | * Note: Global-for-all-devices, set-only-at-init, read-only module |
2065 | * parameteters like 'max_loop' and 'max_part' make things needlessly |
2066 | * complicated, are too static, inflexible and may surprise |
2067 | * userspace tools. Parameters like this in general should be avoided. |
2068 | */ |
2069 | if (!part_shift) |
2070 | set_bit(GD_SUPPRESS_PART_SCAN, addr: &disk->state); |
2071 | mutex_init(&lo->lo_mutex); |
2072 | lo->lo_number = i; |
2073 | spin_lock_init(&lo->lo_lock); |
2074 | spin_lock_init(&lo->lo_work_lock); |
2075 | INIT_WORK(&lo->rootcg_work, loop_rootcg_workfn); |
2076 | INIT_LIST_HEAD(list: &lo->rootcg_cmd_list); |
2077 | disk->major = LOOP_MAJOR; |
2078 | disk->first_minor = i << part_shift; |
2079 | disk->minors = 1 << part_shift; |
2080 | disk->fops = &lo_fops; |
2081 | disk->private_data = lo; |
2082 | disk->queue = lo->lo_queue; |
2083 | disk->events = DISK_EVENT_MEDIA_CHANGE; |
2084 | disk->event_flags = DISK_EVENT_FLAG_UEVENT; |
2085 | sprintf(buf: disk->disk_name, fmt: "loop%d" , i); |
2086 | /* Make this loop device reachable from pathname. */ |
2087 | err = add_disk(disk); |
2088 | if (err) |
2089 | goto out_cleanup_disk; |
2090 | |
2091 | /* Show this loop device. */ |
2092 | mutex_lock(&loop_ctl_mutex); |
2093 | lo->idr_visible = true; |
2094 | mutex_unlock(lock: &loop_ctl_mutex); |
2095 | |
2096 | return i; |
2097 | |
2098 | out_cleanup_disk: |
2099 | put_disk(disk); |
2100 | out_cleanup_tags: |
2101 | blk_mq_free_tag_set(set: &lo->tag_set); |
2102 | out_free_idr: |
2103 | mutex_lock(&loop_ctl_mutex); |
2104 | idr_remove(&loop_index_idr, id: i); |
2105 | mutex_unlock(lock: &loop_ctl_mutex); |
2106 | out_free_dev: |
2107 | kfree(objp: lo); |
2108 | out: |
2109 | return err; |
2110 | } |
2111 | |
2112 | static void loop_remove(struct loop_device *lo) |
2113 | { |
2114 | /* Make this loop device unreachable from pathname. */ |
2115 | del_gendisk(gp: lo->lo_disk); |
2116 | blk_mq_free_tag_set(set: &lo->tag_set); |
2117 | |
2118 | mutex_lock(&loop_ctl_mutex); |
2119 | idr_remove(&loop_index_idr, id: lo->lo_number); |
2120 | mutex_unlock(lock: &loop_ctl_mutex); |
2121 | |
2122 | put_disk(disk: lo->lo_disk); |
2123 | } |
2124 | |
2125 | #ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD |
2126 | static void loop_probe(dev_t dev) |
2127 | { |
2128 | int idx = MINOR(dev) >> part_shift; |
2129 | |
2130 | if (max_loop_specified && max_loop && idx >= max_loop) |
2131 | return; |
2132 | loop_add(i: idx); |
2133 | } |
2134 | #else |
2135 | #define loop_probe NULL |
2136 | #endif /* !CONFIG_BLOCK_LEGACY_AUTOLOAD */ |
2137 | |
2138 | static int loop_control_remove(int idx) |
2139 | { |
2140 | struct loop_device *lo; |
2141 | int ret; |
2142 | |
2143 | if (idx < 0) { |
2144 | pr_warn_once("deleting an unspecified loop device is not supported.\n" ); |
2145 | return -EINVAL; |
2146 | } |
2147 | |
2148 | /* Hide this loop device for serialization. */ |
2149 | ret = mutex_lock_killable(&loop_ctl_mutex); |
2150 | if (ret) |
2151 | return ret; |
2152 | lo = idr_find(&loop_index_idr, id: idx); |
2153 | if (!lo || !lo->idr_visible) |
2154 | ret = -ENODEV; |
2155 | else |
2156 | lo->idr_visible = false; |
2157 | mutex_unlock(lock: &loop_ctl_mutex); |
2158 | if (ret) |
2159 | return ret; |
2160 | |
2161 | /* Check whether this loop device can be removed. */ |
2162 | ret = mutex_lock_killable(&lo->lo_mutex); |
2163 | if (ret) |
2164 | goto mark_visible; |
2165 | if (lo->lo_state != Lo_unbound || disk_openers(disk: lo->lo_disk) > 0) { |
2166 | mutex_unlock(lock: &lo->lo_mutex); |
2167 | ret = -EBUSY; |
2168 | goto mark_visible; |
2169 | } |
2170 | /* Mark this loop device as no more bound, but not quite unbound yet */ |
2171 | lo->lo_state = Lo_deleting; |
2172 | mutex_unlock(lock: &lo->lo_mutex); |
2173 | |
2174 | loop_remove(lo); |
2175 | return 0; |
2176 | |
2177 | mark_visible: |
2178 | /* Show this loop device again. */ |
2179 | mutex_lock(&loop_ctl_mutex); |
2180 | lo->idr_visible = true; |
2181 | mutex_unlock(lock: &loop_ctl_mutex); |
2182 | return ret; |
2183 | } |
2184 | |
2185 | static int loop_control_get_free(int idx) |
2186 | { |
2187 | struct loop_device *lo; |
2188 | int id, ret; |
2189 | |
2190 | ret = mutex_lock_killable(&loop_ctl_mutex); |
2191 | if (ret) |
2192 | return ret; |
2193 | idr_for_each_entry(&loop_index_idr, lo, id) { |
2194 | /* Hitting a race results in creating a new loop device which is harmless. */ |
2195 | if (lo->idr_visible && data_race(lo->lo_state) == Lo_unbound) |
2196 | goto found; |
2197 | } |
2198 | mutex_unlock(lock: &loop_ctl_mutex); |
2199 | return loop_add(i: -1); |
2200 | found: |
2201 | mutex_unlock(lock: &loop_ctl_mutex); |
2202 | return id; |
2203 | } |
2204 | |
2205 | static long loop_control_ioctl(struct file *file, unsigned int cmd, |
2206 | unsigned long parm) |
2207 | { |
2208 | switch (cmd) { |
2209 | case LOOP_CTL_ADD: |
2210 | return loop_add(i: parm); |
2211 | case LOOP_CTL_REMOVE: |
2212 | return loop_control_remove(idx: parm); |
2213 | case LOOP_CTL_GET_FREE: |
2214 | return loop_control_get_free(idx: parm); |
2215 | default: |
2216 | return -ENOSYS; |
2217 | } |
2218 | } |
2219 | |
2220 | static const struct file_operations loop_ctl_fops = { |
2221 | .open = nonseekable_open, |
2222 | .unlocked_ioctl = loop_control_ioctl, |
2223 | .compat_ioctl = loop_control_ioctl, |
2224 | .owner = THIS_MODULE, |
2225 | .llseek = noop_llseek, |
2226 | }; |
2227 | |
2228 | static struct miscdevice loop_misc = { |
2229 | .minor = LOOP_CTRL_MINOR, |
2230 | .name = "loop-control" , |
2231 | .fops = &loop_ctl_fops, |
2232 | }; |
2233 | |
2234 | MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR); |
2235 | MODULE_ALIAS("devname:loop-control" ); |
2236 | |
2237 | static int __init loop_init(void) |
2238 | { |
2239 | int i; |
2240 | int err; |
2241 | |
2242 | part_shift = 0; |
2243 | if (max_part > 0) { |
2244 | part_shift = fls(x: max_part); |
2245 | |
2246 | /* |
2247 | * Adjust max_part according to part_shift as it is exported |
2248 | * to user space so that user can decide correct minor number |
2249 | * if [s]he want to create more devices. |
2250 | * |
2251 | * Note that -1 is required because partition 0 is reserved |
2252 | * for the whole disk. |
2253 | */ |
2254 | max_part = (1UL << part_shift) - 1; |
2255 | } |
2256 | |
2257 | if ((1UL << part_shift) > DISK_MAX_PARTS) { |
2258 | err = -EINVAL; |
2259 | goto err_out; |
2260 | } |
2261 | |
2262 | if (max_loop > 1UL << (MINORBITS - part_shift)) { |
2263 | err = -EINVAL; |
2264 | goto err_out; |
2265 | } |
2266 | |
2267 | err = misc_register(misc: &loop_misc); |
2268 | if (err < 0) |
2269 | goto err_out; |
2270 | |
2271 | |
2272 | if (__register_blkdev(LOOP_MAJOR, name: "loop" , probe: loop_probe)) { |
2273 | err = -EIO; |
2274 | goto misc_out; |
2275 | } |
2276 | |
2277 | /* pre-create number of devices given by config or max_loop */ |
2278 | for (i = 0; i < max_loop; i++) |
2279 | loop_add(i); |
2280 | |
2281 | printk(KERN_INFO "loop: module loaded\n" ); |
2282 | return 0; |
2283 | |
2284 | misc_out: |
2285 | misc_deregister(misc: &loop_misc); |
2286 | err_out: |
2287 | return err; |
2288 | } |
2289 | |
2290 | static void __exit loop_exit(void) |
2291 | { |
2292 | struct loop_device *lo; |
2293 | int id; |
2294 | |
2295 | unregister_blkdev(LOOP_MAJOR, name: "loop" ); |
2296 | misc_deregister(misc: &loop_misc); |
2297 | |
2298 | /* |
2299 | * There is no need to use loop_ctl_mutex here, for nobody else can |
2300 | * access loop_index_idr when this module is unloading (unless forced |
2301 | * module unloading is requested). If this is not a clean unloading, |
2302 | * we have no means to avoid kernel crash. |
2303 | */ |
2304 | idr_for_each_entry(&loop_index_idr, lo, id) |
2305 | loop_remove(lo); |
2306 | |
2307 | idr_destroy(&loop_index_idr); |
2308 | } |
2309 | |
2310 | module_init(loop_init); |
2311 | module_exit(loop_exit); |
2312 | |
2313 | #ifndef MODULE |
2314 | static int __init max_loop_setup(char *str) |
2315 | { |
2316 | max_loop = simple_strtol(str, NULL, 0); |
2317 | #ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD |
2318 | max_loop_specified = true; |
2319 | #endif |
2320 | return 1; |
2321 | } |
2322 | |
2323 | __setup("max_loop=" , max_loop_setup); |
2324 | #endif |
2325 | |