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 | /* |
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(bdev: backing_bdev); |
177 | |
178 | if (queue_logical_block_size(q: 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, datasync: 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(q: lo->lo_queue); |
213 | lo->use_dio = use_dio; |
214 | if (use_dio) { |
215 | blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, q: lo->lo_queue); |
216 | lo->lo_flags |= LO_FLAGS_DIRECT_IO; |
217 | } else { |
218 | blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q: lo->lo_queue); |
219 | lo->lo_flags &= ~LO_FLAGS_DIRECT_IO; |
220 | } |
221 | if (lo->lo_state == Lo_bound) |
222 | blk_mq_unfreeze_queue(q: lo->lo_queue); |
223 | } |
224 | |
225 | /** |
226 | * loop_set_size() - sets device size and notifies userspace |
227 | * @lo: struct loop_device to set the size for |
228 | * @size: new size of the loop device |
229 | * |
230 | * Callers must validate that the size passed into this function fits into |
231 | * a sector_t, eg using loop_validate_size() |
232 | */ |
233 | static void loop_set_size(struct loop_device *lo, loff_t size) |
234 | { |
235 | if (!set_capacity_and_notify(disk: lo->lo_disk, size)) |
236 | kobject_uevent(kobj: &disk_to_dev(lo->lo_disk)->kobj, action: KOBJ_CHANGE); |
237 | } |
238 | |
239 | static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos) |
240 | { |
241 | struct iov_iter i; |
242 | ssize_t bw; |
243 | |
244 | iov_iter_bvec(i: &i, ITER_SOURCE, bvec, nr_segs: 1, count: bvec->bv_len); |
245 | |
246 | bw = vfs_iter_write(file, iter: &i, ppos, flags: 0); |
247 | |
248 | if (likely(bw == bvec->bv_len)) |
249 | return 0; |
250 | |
251 | printk_ratelimited(KERN_ERR |
252 | "loop: Write error at byte offset %llu, length %i.\n" , |
253 | (unsigned long long)*ppos, bvec->bv_len); |
254 | if (bw >= 0) |
255 | bw = -EIO; |
256 | return bw; |
257 | } |
258 | |
259 | static int lo_write_simple(struct loop_device *lo, struct request *rq, |
260 | loff_t pos) |
261 | { |
262 | struct bio_vec bvec; |
263 | struct req_iterator iter; |
264 | int ret = 0; |
265 | |
266 | rq_for_each_segment(bvec, rq, iter) { |
267 | ret = lo_write_bvec(file: lo->lo_backing_file, bvec: &bvec, ppos: &pos); |
268 | if (ret < 0) |
269 | break; |
270 | cond_resched(); |
271 | } |
272 | |
273 | return ret; |
274 | } |
275 | |
276 | static int lo_read_simple(struct loop_device *lo, struct request *rq, |
277 | loff_t pos) |
278 | { |
279 | struct bio_vec bvec; |
280 | struct req_iterator iter; |
281 | struct iov_iter i; |
282 | ssize_t len; |
283 | |
284 | rq_for_each_segment(bvec, rq, iter) { |
285 | iov_iter_bvec(i: &i, ITER_DEST, bvec: &bvec, nr_segs: 1, count: bvec.bv_len); |
286 | len = vfs_iter_read(file: lo->lo_backing_file, iter: &i, ppos: &pos, flags: 0); |
287 | if (len < 0) |
288 | return len; |
289 | |
290 | flush_dcache_page(page: bvec.bv_page); |
291 | |
292 | if (len != bvec.bv_len) { |
293 | struct bio *bio; |
294 | |
295 | __rq_for_each_bio(bio, rq) |
296 | zero_fill_bio(bio); |
297 | break; |
298 | } |
299 | cond_resched(); |
300 | } |
301 | |
302 | return 0; |
303 | } |
304 | |
305 | static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos, |
306 | int mode) |
307 | { |
308 | /* |
309 | * We use fallocate to manipulate the space mappings used by the image |
310 | * a.k.a. discard/zerorange. |
311 | */ |
312 | struct file *file = lo->lo_backing_file; |
313 | int ret; |
314 | |
315 | mode |= FALLOC_FL_KEEP_SIZE; |
316 | |
317 | if (!bdev_max_discard_sectors(bdev: lo->lo_device)) |
318 | return -EOPNOTSUPP; |
319 | |
320 | ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq)); |
321 | if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP)) |
322 | return -EIO; |
323 | return ret; |
324 | } |
325 | |
326 | static int lo_req_flush(struct loop_device *lo, struct request *rq) |
327 | { |
328 | int ret = vfs_fsync(file: lo->lo_backing_file, datasync: 0); |
329 | if (unlikely(ret && ret != -EINVAL)) |
330 | ret = -EIO; |
331 | |
332 | return ret; |
333 | } |
334 | |
335 | static void lo_complete_rq(struct request *rq) |
336 | { |
337 | struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); |
338 | blk_status_t ret = BLK_STS_OK; |
339 | |
340 | if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) || |
341 | req_op(req: rq) != REQ_OP_READ) { |
342 | if (cmd->ret < 0) |
343 | ret = errno_to_blk_status(errno: cmd->ret); |
344 | goto end_io; |
345 | } |
346 | |
347 | /* |
348 | * Short READ - if we got some data, advance our request and |
349 | * retry it. If we got no data, end the rest with EIO. |
350 | */ |
351 | if (cmd->ret) { |
352 | blk_update_request(rq, BLK_STS_OK, nr_bytes: cmd->ret); |
353 | cmd->ret = 0; |
354 | blk_mq_requeue_request(rq, kick_requeue_list: true); |
355 | } else { |
356 | if (cmd->use_aio) { |
357 | struct bio *bio = rq->bio; |
358 | |
359 | while (bio) { |
360 | zero_fill_bio(bio); |
361 | bio = bio->bi_next; |
362 | } |
363 | } |
364 | ret = BLK_STS_IOERR; |
365 | end_io: |
366 | blk_mq_end_request(rq, error: ret); |
367 | } |
368 | } |
369 | |
370 | static void lo_rw_aio_do_completion(struct loop_cmd *cmd) |
371 | { |
372 | struct request *rq = blk_mq_rq_from_pdu(pdu: cmd); |
373 | |
374 | if (!atomic_dec_and_test(v: &cmd->ref)) |
375 | return; |
376 | kfree(objp: cmd->bvec); |
377 | cmd->bvec = NULL; |
378 | if (likely(!blk_should_fake_timeout(rq->q))) |
379 | blk_mq_complete_request(rq); |
380 | } |
381 | |
382 | static void lo_rw_aio_complete(struct kiocb *iocb, long ret) |
383 | { |
384 | struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb); |
385 | |
386 | cmd->ret = ret; |
387 | lo_rw_aio_do_completion(cmd); |
388 | } |
389 | |
390 | static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, |
391 | loff_t pos, int rw) |
392 | { |
393 | struct iov_iter iter; |
394 | struct req_iterator rq_iter; |
395 | struct bio_vec *bvec; |
396 | struct request *rq = blk_mq_rq_from_pdu(pdu: cmd); |
397 | struct bio *bio = rq->bio; |
398 | struct file *file = lo->lo_backing_file; |
399 | struct bio_vec tmp; |
400 | unsigned int offset; |
401 | int nr_bvec = 0; |
402 | int ret; |
403 | |
404 | rq_for_each_bvec(tmp, rq, rq_iter) |
405 | nr_bvec++; |
406 | |
407 | if (rq->bio != rq->biotail) { |
408 | |
409 | bvec = kmalloc_array(n: nr_bvec, size: sizeof(struct bio_vec), |
410 | GFP_NOIO); |
411 | if (!bvec) |
412 | return -EIO; |
413 | cmd->bvec = bvec; |
414 | |
415 | /* |
416 | * The bios of the request may be started from the middle of |
417 | * the 'bvec' because of bio splitting, so we can't directly |
418 | * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec |
419 | * API will take care of all details for us. |
420 | */ |
421 | rq_for_each_bvec(tmp, rq, rq_iter) { |
422 | *bvec = tmp; |
423 | bvec++; |
424 | } |
425 | bvec = cmd->bvec; |
426 | offset = 0; |
427 | } else { |
428 | /* |
429 | * Same here, this bio may be started from the middle of the |
430 | * 'bvec' because of bio splitting, so offset from the bvec |
431 | * must be passed to iov iterator |
432 | */ |
433 | offset = bio->bi_iter.bi_bvec_done; |
434 | bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); |
435 | } |
436 | atomic_set(v: &cmd->ref, i: 2); |
437 | |
438 | iov_iter_bvec(i: &iter, direction: rw, bvec, nr_segs: nr_bvec, count: blk_rq_bytes(rq)); |
439 | iter.iov_offset = offset; |
440 | |
441 | cmd->iocb.ki_pos = pos; |
442 | cmd->iocb.ki_filp = file; |
443 | cmd->iocb.ki_complete = lo_rw_aio_complete; |
444 | cmd->iocb.ki_flags = IOCB_DIRECT; |
445 | cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0); |
446 | |
447 | if (rw == ITER_SOURCE) |
448 | ret = call_write_iter(file, kio: &cmd->iocb, iter: &iter); |
449 | else |
450 | ret = call_read_iter(file, kio: &cmd->iocb, iter: &iter); |
451 | |
452 | lo_rw_aio_do_completion(cmd); |
453 | |
454 | if (ret != -EIOCBQUEUED) |
455 | lo_rw_aio_complete(iocb: &cmd->iocb, ret); |
456 | return 0; |
457 | } |
458 | |
459 | static int do_req_filebacked(struct loop_device *lo, struct request *rq) |
460 | { |
461 | struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); |
462 | loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset; |
463 | |
464 | /* |
465 | * lo_write_simple and lo_read_simple should have been covered |
466 | * by io submit style function like lo_rw_aio(), one blocker |
467 | * is that lo_read_simple() need to call flush_dcache_page after |
468 | * the page is written from kernel, and it isn't easy to handle |
469 | * this in io submit style function which submits all segments |
470 | * of the req at one time. And direct read IO doesn't need to |
471 | * run flush_dcache_page(). |
472 | */ |
473 | switch (req_op(req: rq)) { |
474 | case REQ_OP_FLUSH: |
475 | return lo_req_flush(lo, rq); |
476 | case REQ_OP_WRITE_ZEROES: |
477 | /* |
478 | * If the caller doesn't want deallocation, call zeroout to |
479 | * write zeroes the range. Otherwise, punch them out. |
480 | */ |
481 | return lo_fallocate(lo, rq, pos, |
482 | mode: (rq->cmd_flags & REQ_NOUNMAP) ? |
483 | FALLOC_FL_ZERO_RANGE : |
484 | FALLOC_FL_PUNCH_HOLE); |
485 | case REQ_OP_DISCARD: |
486 | return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE); |
487 | case REQ_OP_WRITE: |
488 | if (cmd->use_aio) |
489 | return lo_rw_aio(lo, cmd, pos, ITER_SOURCE); |
490 | else |
491 | return lo_write_simple(lo, rq, pos); |
492 | case REQ_OP_READ: |
493 | if (cmd->use_aio) |
494 | return lo_rw_aio(lo, cmd, pos, ITER_DEST); |
495 | else |
496 | return lo_read_simple(lo, rq, pos); |
497 | default: |
498 | WARN_ON_ONCE(1); |
499 | return -EIO; |
500 | } |
501 | } |
502 | |
503 | static inline void loop_update_dio(struct loop_device *lo) |
504 | { |
505 | __loop_update_dio(lo, dio: (lo->lo_backing_file->f_flags & O_DIRECT) | |
506 | lo->use_dio); |
507 | } |
508 | |
509 | static void loop_reread_partitions(struct loop_device *lo) |
510 | { |
511 | int rc; |
512 | |
513 | mutex_lock(&lo->lo_disk->open_mutex); |
514 | rc = bdev_disk_changed(disk: lo->lo_disk, invalidate: false); |
515 | mutex_unlock(lock: &lo->lo_disk->open_mutex); |
516 | if (rc) |
517 | pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n" , |
518 | __func__, lo->lo_number, lo->lo_file_name, rc); |
519 | } |
520 | |
521 | static inline int is_loop_device(struct file *file) |
522 | { |
523 | struct inode *i = file->f_mapping->host; |
524 | |
525 | return i && S_ISBLK(i->i_mode) && imajor(inode: i) == LOOP_MAJOR; |
526 | } |
527 | |
528 | static int loop_validate_file(struct file *file, struct block_device *bdev) |
529 | { |
530 | struct inode *inode = file->f_mapping->host; |
531 | struct file *f = file; |
532 | |
533 | /* Avoid recursion */ |
534 | while (is_loop_device(file: f)) { |
535 | struct loop_device *l; |
536 | |
537 | lockdep_assert_held(&loop_validate_mutex); |
538 | if (f->f_mapping->host->i_rdev == bdev->bd_dev) |
539 | return -EBADF; |
540 | |
541 | l = I_BDEV(inode: f->f_mapping->host)->bd_disk->private_data; |
542 | if (l->lo_state != Lo_bound) |
543 | return -EINVAL; |
544 | /* Order wrt setting lo->lo_backing_file in loop_configure(). */ |
545 | rmb(); |
546 | f = l->lo_backing_file; |
547 | } |
548 | if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode)) |
549 | return -EINVAL; |
550 | return 0; |
551 | } |
552 | |
553 | /* |
554 | * loop_change_fd switched the backing store of a loopback device to |
555 | * a new file. This is useful for operating system installers to free up |
556 | * the original file and in High Availability environments to switch to |
557 | * an alternative location for the content in case of server meltdown. |
558 | * This can only work if the loop device is used read-only, and if the |
559 | * new backing store is the same size and type as the old backing store. |
560 | */ |
561 | static int loop_change_fd(struct loop_device *lo, struct block_device *bdev, |
562 | unsigned int arg) |
563 | { |
564 | struct file *file = fget(fd: arg); |
565 | struct file *old_file; |
566 | int error; |
567 | bool partscan; |
568 | bool is_loop; |
569 | |
570 | if (!file) |
571 | return -EBADF; |
572 | |
573 | /* suppress uevents while reconfiguring the device */ |
574 | dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), val: 1); |
575 | |
576 | is_loop = is_loop_device(file); |
577 | error = loop_global_lock_killable(lo, global: is_loop); |
578 | if (error) |
579 | goto out_putf; |
580 | error = -ENXIO; |
581 | if (lo->lo_state != Lo_bound) |
582 | goto out_err; |
583 | |
584 | /* the loop device has to be read-only */ |
585 | error = -EINVAL; |
586 | if (!(lo->lo_flags & LO_FLAGS_READ_ONLY)) |
587 | goto out_err; |
588 | |
589 | error = loop_validate_file(file, bdev); |
590 | if (error) |
591 | goto out_err; |
592 | |
593 | old_file = lo->lo_backing_file; |
594 | |
595 | error = -EINVAL; |
596 | |
597 | /* size of the new backing store needs to be the same */ |
598 | if (get_loop_size(lo, file) != get_loop_size(lo, file: old_file)) |
599 | goto out_err; |
600 | |
601 | /* and ... switch */ |
602 | disk_force_media_change(disk: lo->lo_disk); |
603 | blk_mq_freeze_queue(q: lo->lo_queue); |
604 | mapping_set_gfp_mask(m: old_file->f_mapping, mask: lo->old_gfp_mask); |
605 | lo->lo_backing_file = file; |
606 | lo->old_gfp_mask = mapping_gfp_mask(mapping: file->f_mapping); |
607 | mapping_set_gfp_mask(m: file->f_mapping, |
608 | mask: lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); |
609 | loop_update_dio(lo); |
610 | blk_mq_unfreeze_queue(q: lo->lo_queue); |
611 | partscan = lo->lo_flags & LO_FLAGS_PARTSCAN; |
612 | loop_global_unlock(lo, global: is_loop); |
613 | |
614 | /* |
615 | * Flush loop_validate_file() before fput(), for l->lo_backing_file |
616 | * might be pointing at old_file which might be the last reference. |
617 | */ |
618 | if (!is_loop) { |
619 | mutex_lock(&loop_validate_mutex); |
620 | mutex_unlock(lock: &loop_validate_mutex); |
621 | } |
622 | /* |
623 | * We must drop file reference outside of lo_mutex as dropping |
624 | * the file ref can take open_mutex which creates circular locking |
625 | * dependency. |
626 | */ |
627 | fput(old_file); |
628 | if (partscan) |
629 | loop_reread_partitions(lo); |
630 | |
631 | error = 0; |
632 | done: |
633 | /* enable and uncork uevent now that we are done */ |
634 | dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), val: 0); |
635 | return error; |
636 | |
637 | out_err: |
638 | loop_global_unlock(lo, global: is_loop); |
639 | out_putf: |
640 | fput(file); |
641 | goto done; |
642 | } |
643 | |
644 | /* loop sysfs attributes */ |
645 | |
646 | static ssize_t loop_attr_show(struct device *dev, char *page, |
647 | ssize_t (*callback)(struct loop_device *, char *)) |
648 | { |
649 | struct gendisk *disk = dev_to_disk(dev); |
650 | struct loop_device *lo = disk->private_data; |
651 | |
652 | return callback(lo, page); |
653 | } |
654 | |
655 | #define LOOP_ATTR_RO(_name) \ |
656 | static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \ |
657 | static ssize_t loop_attr_do_show_##_name(struct device *d, \ |
658 | struct device_attribute *attr, char *b) \ |
659 | { \ |
660 | return loop_attr_show(d, b, loop_attr_##_name##_show); \ |
661 | } \ |
662 | static struct device_attribute loop_attr_##_name = \ |
663 | __ATTR(_name, 0444, loop_attr_do_show_##_name, NULL); |
664 | |
665 | static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf) |
666 | { |
667 | ssize_t ret; |
668 | char *p = NULL; |
669 | |
670 | spin_lock_irq(lock: &lo->lo_lock); |
671 | if (lo->lo_backing_file) |
672 | p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1); |
673 | spin_unlock_irq(lock: &lo->lo_lock); |
674 | |
675 | if (IS_ERR_OR_NULL(ptr: p)) |
676 | ret = PTR_ERR(ptr: p); |
677 | else { |
678 | ret = strlen(p); |
679 | memmove(buf, p, ret); |
680 | buf[ret++] = '\n'; |
681 | buf[ret] = 0; |
682 | } |
683 | |
684 | return ret; |
685 | } |
686 | |
687 | static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf) |
688 | { |
689 | return sysfs_emit(buf, fmt: "%llu\n" , (unsigned long long)lo->lo_offset); |
690 | } |
691 | |
692 | static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf) |
693 | { |
694 | return sysfs_emit(buf, fmt: "%llu\n" , (unsigned long long)lo->lo_sizelimit); |
695 | } |
696 | |
697 | static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf) |
698 | { |
699 | int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR); |
700 | |
701 | return sysfs_emit(buf, fmt: "%s\n" , autoclear ? "1" : "0" ); |
702 | } |
703 | |
704 | static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf) |
705 | { |
706 | int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN); |
707 | |
708 | return sysfs_emit(buf, fmt: "%s\n" , partscan ? "1" : "0" ); |
709 | } |
710 | |
711 | static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf) |
712 | { |
713 | int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO); |
714 | |
715 | return sysfs_emit(buf, fmt: "%s\n" , dio ? "1" : "0" ); |
716 | } |
717 | |
718 | LOOP_ATTR_RO(backing_file); |
719 | LOOP_ATTR_RO(offset); |
720 | LOOP_ATTR_RO(sizelimit); |
721 | LOOP_ATTR_RO(autoclear); |
722 | LOOP_ATTR_RO(partscan); |
723 | LOOP_ATTR_RO(dio); |
724 | |
725 | static struct attribute *loop_attrs[] = { |
726 | &loop_attr_backing_file.attr, |
727 | &loop_attr_offset.attr, |
728 | &loop_attr_sizelimit.attr, |
729 | &loop_attr_autoclear.attr, |
730 | &loop_attr_partscan.attr, |
731 | &loop_attr_dio.attr, |
732 | NULL, |
733 | }; |
734 | |
735 | static struct attribute_group loop_attribute_group = { |
736 | .name = "loop" , |
737 | .attrs= loop_attrs, |
738 | }; |
739 | |
740 | static void loop_sysfs_init(struct loop_device *lo) |
741 | { |
742 | lo->sysfs_inited = !sysfs_create_group(kobj: &disk_to_dev(lo->lo_disk)->kobj, |
743 | grp: &loop_attribute_group); |
744 | } |
745 | |
746 | static void loop_sysfs_exit(struct loop_device *lo) |
747 | { |
748 | if (lo->sysfs_inited) |
749 | sysfs_remove_group(kobj: &disk_to_dev(lo->lo_disk)->kobj, |
750 | grp: &loop_attribute_group); |
751 | } |
752 | |
753 | static void loop_config_discard(struct loop_device *lo, |
754 | struct queue_limits *lim) |
755 | { |
756 | struct file *file = lo->lo_backing_file; |
757 | struct inode *inode = file->f_mapping->host; |
758 | u32 granularity = 0, max_discard_sectors = 0; |
759 | struct kstatfs sbuf; |
760 | |
761 | /* |
762 | * If the backing device is a block device, mirror its zeroing |
763 | * capability. Set the discard sectors to the block device's zeroing |
764 | * capabilities because loop discards result in blkdev_issue_zeroout(), |
765 | * not blkdev_issue_discard(). This maintains consistent behavior with |
766 | * file-backed loop devices: discarded regions read back as zero. |
767 | */ |
768 | if (S_ISBLK(inode->i_mode)) { |
769 | struct request_queue *backingq = bdev_get_queue(bdev: I_BDEV(inode)); |
770 | |
771 | max_discard_sectors = backingq->limits.max_write_zeroes_sectors; |
772 | granularity = bdev_discard_granularity(bdev: I_BDEV(inode)) ?: |
773 | queue_physical_block_size(q: backingq); |
774 | |
775 | /* |
776 | * We use punch hole to reclaim the free space used by the |
777 | * image a.k.a. discard. |
778 | */ |
779 | } else if (file->f_op->fallocate && !vfs_statfs(&file->f_path, &sbuf)) { |
780 | max_discard_sectors = UINT_MAX >> 9; |
781 | granularity = sbuf.f_bsize; |
782 | } |
783 | |
784 | lim->max_hw_discard_sectors = max_discard_sectors; |
785 | lim->max_write_zeroes_sectors = max_discard_sectors; |
786 | if (max_discard_sectors) |
787 | lim->discard_granularity = granularity; |
788 | else |
789 | lim->discard_granularity = 0; |
790 | } |
791 | |
792 | struct loop_worker { |
793 | struct rb_node rb_node; |
794 | struct work_struct work; |
795 | struct list_head cmd_list; |
796 | struct list_head idle_list; |
797 | struct loop_device *lo; |
798 | struct cgroup_subsys_state *blkcg_css; |
799 | unsigned long last_ran_at; |
800 | }; |
801 | |
802 | static void loop_workfn(struct work_struct *work); |
803 | |
804 | #ifdef CONFIG_BLK_CGROUP |
805 | static inline int queue_on_root_worker(struct cgroup_subsys_state *css) |
806 | { |
807 | return !css || css == blkcg_root_css; |
808 | } |
809 | #else |
810 | static inline int queue_on_root_worker(struct cgroup_subsys_state *css) |
811 | { |
812 | return !css; |
813 | } |
814 | #endif |
815 | |
816 | static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd) |
817 | { |
818 | struct rb_node **node, *parent = NULL; |
819 | struct loop_worker *cur_worker, *worker = NULL; |
820 | struct work_struct *work; |
821 | struct list_head *cmd_list; |
822 | |
823 | spin_lock_irq(lock: &lo->lo_work_lock); |
824 | |
825 | if (queue_on_root_worker(css: cmd->blkcg_css)) |
826 | goto queue_work; |
827 | |
828 | node = &lo->worker_tree.rb_node; |
829 | |
830 | while (*node) { |
831 | parent = *node; |
832 | cur_worker = container_of(*node, struct loop_worker, rb_node); |
833 | if (cur_worker->blkcg_css == cmd->blkcg_css) { |
834 | worker = cur_worker; |
835 | break; |
836 | } else if ((long)cur_worker->blkcg_css < (long)cmd->blkcg_css) { |
837 | node = &(*node)->rb_left; |
838 | } else { |
839 | node = &(*node)->rb_right; |
840 | } |
841 | } |
842 | if (worker) |
843 | goto queue_work; |
844 | |
845 | worker = kzalloc(size: sizeof(struct loop_worker), GFP_NOWAIT | __GFP_NOWARN); |
846 | /* |
847 | * In the event we cannot allocate a worker, just queue on the |
848 | * rootcg worker and issue the I/O as the rootcg |
849 | */ |
850 | if (!worker) { |
851 | cmd->blkcg_css = NULL; |
852 | if (cmd->memcg_css) |
853 | css_put(css: cmd->memcg_css); |
854 | cmd->memcg_css = NULL; |
855 | goto queue_work; |
856 | } |
857 | |
858 | worker->blkcg_css = cmd->blkcg_css; |
859 | css_get(css: worker->blkcg_css); |
860 | INIT_WORK(&worker->work, loop_workfn); |
861 | INIT_LIST_HEAD(list: &worker->cmd_list); |
862 | INIT_LIST_HEAD(list: &worker->idle_list); |
863 | worker->lo = lo; |
864 | rb_link_node(node: &worker->rb_node, parent, rb_link: node); |
865 | rb_insert_color(&worker->rb_node, &lo->worker_tree); |
866 | queue_work: |
867 | if (worker) { |
868 | /* |
869 | * We need to remove from the idle list here while |
870 | * holding the lock so that the idle timer doesn't |
871 | * free the worker |
872 | */ |
873 | if (!list_empty(head: &worker->idle_list)) |
874 | list_del_init(entry: &worker->idle_list); |
875 | work = &worker->work; |
876 | cmd_list = &worker->cmd_list; |
877 | } else { |
878 | work = &lo->rootcg_work; |
879 | cmd_list = &lo->rootcg_cmd_list; |
880 | } |
881 | list_add_tail(new: &cmd->list_entry, head: cmd_list); |
882 | queue_work(wq: lo->workqueue, work); |
883 | spin_unlock_irq(lock: &lo->lo_work_lock); |
884 | } |
885 | |
886 | static void loop_set_timer(struct loop_device *lo) |
887 | { |
888 | timer_reduce(timer: &lo->timer, expires: jiffies + LOOP_IDLE_WORKER_TIMEOUT); |
889 | } |
890 | |
891 | static void loop_free_idle_workers(struct loop_device *lo, bool delete_all) |
892 | { |
893 | struct loop_worker *pos, *worker; |
894 | |
895 | spin_lock_irq(lock: &lo->lo_work_lock); |
896 | list_for_each_entry_safe(worker, pos, &lo->idle_worker_list, |
897 | idle_list) { |
898 | if (!delete_all && |
899 | time_is_after_jiffies(worker->last_ran_at + |
900 | LOOP_IDLE_WORKER_TIMEOUT)) |
901 | break; |
902 | list_del(entry: &worker->idle_list); |
903 | rb_erase(&worker->rb_node, &lo->worker_tree); |
904 | css_put(css: worker->blkcg_css); |
905 | kfree(objp: worker); |
906 | } |
907 | if (!list_empty(head: &lo->idle_worker_list)) |
908 | loop_set_timer(lo); |
909 | spin_unlock_irq(lock: &lo->lo_work_lock); |
910 | } |
911 | |
912 | static void loop_free_idle_workers_timer(struct timer_list *timer) |
913 | { |
914 | struct loop_device *lo = container_of(timer, struct loop_device, timer); |
915 | |
916 | return loop_free_idle_workers(lo, delete_all: false); |
917 | } |
918 | |
919 | static void loop_update_rotational(struct loop_device *lo) |
920 | { |
921 | struct file *file = lo->lo_backing_file; |
922 | struct inode *file_inode = file->f_mapping->host; |
923 | struct block_device *file_bdev = file_inode->i_sb->s_bdev; |
924 | struct request_queue *q = lo->lo_queue; |
925 | bool nonrot = true; |
926 | |
927 | /* not all filesystems (e.g. tmpfs) have a sb->s_bdev */ |
928 | if (file_bdev) |
929 | nonrot = bdev_nonrot(bdev: file_bdev); |
930 | |
931 | if (nonrot) |
932 | blk_queue_flag_set(QUEUE_FLAG_NONROT, q); |
933 | else |
934 | blk_queue_flag_clear(QUEUE_FLAG_NONROT, q); |
935 | } |
936 | |
937 | /** |
938 | * loop_set_status_from_info - configure device from loop_info |
939 | * @lo: struct loop_device to configure |
940 | * @info: struct loop_info64 to configure the device with |
941 | * |
942 | * Configures the loop device parameters according to the passed |
943 | * in loop_info64 configuration. |
944 | */ |
945 | static int |
946 | loop_set_status_from_info(struct loop_device *lo, |
947 | const struct loop_info64 *info) |
948 | { |
949 | if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE) |
950 | return -EINVAL; |
951 | |
952 | switch (info->lo_encrypt_type) { |
953 | case LO_CRYPT_NONE: |
954 | break; |
955 | case LO_CRYPT_XOR: |
956 | pr_warn("support for the xor transformation has been removed.\n" ); |
957 | return -EINVAL; |
958 | case LO_CRYPT_CRYPTOAPI: |
959 | pr_warn("support for cryptoloop has been removed. Use dm-crypt instead.\n" ); |
960 | return -EINVAL; |
961 | default: |
962 | return -EINVAL; |
963 | } |
964 | |
965 | /* Avoid assigning overflow values */ |
966 | if (info->lo_offset > LLONG_MAX || info->lo_sizelimit > LLONG_MAX) |
967 | return -EOVERFLOW; |
968 | |
969 | lo->lo_offset = info->lo_offset; |
970 | lo->lo_sizelimit = info->lo_sizelimit; |
971 | |
972 | memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE); |
973 | lo->lo_file_name[LO_NAME_SIZE-1] = 0; |
974 | lo->lo_flags = info->lo_flags; |
975 | return 0; |
976 | } |
977 | |
978 | static int loop_reconfigure_limits(struct loop_device *lo, unsigned short bsize, |
979 | bool update_discard_settings) |
980 | { |
981 | struct queue_limits lim; |
982 | |
983 | lim = queue_limits_start_update(q: lo->lo_queue); |
984 | lim.logical_block_size = bsize; |
985 | lim.physical_block_size = bsize; |
986 | lim.io_min = bsize; |
987 | if (update_discard_settings) |
988 | loop_config_discard(lo, lim: &lim); |
989 | return queue_limits_commit_update(q: lo->lo_queue, lim: &lim); |
990 | } |
991 | |
992 | static int loop_configure(struct loop_device *lo, blk_mode_t mode, |
993 | struct block_device *bdev, |
994 | const struct loop_config *config) |
995 | { |
996 | struct file *file = fget(fd: config->fd); |
997 | struct inode *inode; |
998 | struct address_space *mapping; |
999 | int error; |
1000 | loff_t size; |
1001 | bool partscan; |
1002 | unsigned short bsize; |
1003 | bool is_loop; |
1004 | |
1005 | if (!file) |
1006 | return -EBADF; |
1007 | is_loop = is_loop_device(file); |
1008 | |
1009 | /* This is safe, since we have a reference from open(). */ |
1010 | __module_get(THIS_MODULE); |
1011 | |
1012 | /* |
1013 | * If we don't hold exclusive handle for the device, upgrade to it |
1014 | * here to avoid changing device under exclusive owner. |
1015 | */ |
1016 | if (!(mode & BLK_OPEN_EXCL)) { |
1017 | error = bd_prepare_to_claim(bdev, holder: loop_configure, NULL); |
1018 | if (error) |
1019 | goto out_putf; |
1020 | } |
1021 | |
1022 | error = loop_global_lock_killable(lo, global: is_loop); |
1023 | if (error) |
1024 | goto out_bdev; |
1025 | |
1026 | error = -EBUSY; |
1027 | if (lo->lo_state != Lo_unbound) |
1028 | goto out_unlock; |
1029 | |
1030 | error = loop_validate_file(file, bdev); |
1031 | if (error) |
1032 | goto out_unlock; |
1033 | |
1034 | mapping = file->f_mapping; |
1035 | inode = mapping->host; |
1036 | |
1037 | if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) { |
1038 | error = -EINVAL; |
1039 | goto out_unlock; |
1040 | } |
1041 | |
1042 | if (config->block_size) { |
1043 | error = blk_validate_block_size(bsize: config->block_size); |
1044 | if (error) |
1045 | goto out_unlock; |
1046 | } |
1047 | |
1048 | error = loop_set_status_from_info(lo, info: &config->info); |
1049 | if (error) |
1050 | goto out_unlock; |
1051 | |
1052 | if (!(file->f_mode & FMODE_WRITE) || !(mode & BLK_OPEN_WRITE) || |
1053 | !file->f_op->write_iter) |
1054 | lo->lo_flags |= LO_FLAGS_READ_ONLY; |
1055 | |
1056 | if (!lo->workqueue) { |
1057 | lo->workqueue = alloc_workqueue(fmt: "loop%d" , |
1058 | flags: WQ_UNBOUND | WQ_FREEZABLE, |
1059 | max_active: 0, lo->lo_number); |
1060 | if (!lo->workqueue) { |
1061 | error = -ENOMEM; |
1062 | goto out_unlock; |
1063 | } |
1064 | } |
1065 | |
1066 | /* suppress uevents while reconfiguring the device */ |
1067 | dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), val: 1); |
1068 | |
1069 | disk_force_media_change(disk: lo->lo_disk); |
1070 | set_disk_ro(disk: lo->lo_disk, read_only: (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0); |
1071 | |
1072 | lo->use_dio = lo->lo_flags & LO_FLAGS_DIRECT_IO; |
1073 | lo->lo_device = bdev; |
1074 | lo->lo_backing_file = file; |
1075 | lo->old_gfp_mask = mapping_gfp_mask(mapping); |
1076 | mapping_set_gfp_mask(m: mapping, mask: lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); |
1077 | |
1078 | if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync) |
1079 | blk_queue_write_cache(q: lo->lo_queue, enabled: true, fua: false); |
1080 | |
1081 | if (config->block_size) |
1082 | bsize = config->block_size; |
1083 | else if ((lo->lo_backing_file->f_flags & O_DIRECT) && inode->i_sb->s_bdev) |
1084 | /* In case of direct I/O, match underlying block size */ |
1085 | bsize = bdev_logical_block_size(bdev: inode->i_sb->s_bdev); |
1086 | else |
1087 | bsize = 512; |
1088 | |
1089 | error = loop_reconfigure_limits(lo, bsize, update_discard_settings: true); |
1090 | if (WARN_ON_ONCE(error)) |
1091 | goto out_unlock; |
1092 | |
1093 | loop_update_rotational(lo); |
1094 | loop_update_dio(lo); |
1095 | loop_sysfs_init(lo); |
1096 | |
1097 | size = get_loop_size(lo, file); |
1098 | loop_set_size(lo, size); |
1099 | |
1100 | /* Order wrt reading lo_state in loop_validate_file(). */ |
1101 | wmb(); |
1102 | |
1103 | lo->lo_state = Lo_bound; |
1104 | if (part_shift) |
1105 | lo->lo_flags |= LO_FLAGS_PARTSCAN; |
1106 | partscan = lo->lo_flags & LO_FLAGS_PARTSCAN; |
1107 | if (partscan) |
1108 | clear_bit(GD_SUPPRESS_PART_SCAN, addr: &lo->lo_disk->state); |
1109 | |
1110 | /* enable and uncork uevent now that we are done */ |
1111 | dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), val: 0); |
1112 | |
1113 | loop_global_unlock(lo, global: is_loop); |
1114 | if (partscan) |
1115 | loop_reread_partitions(lo); |
1116 | |
1117 | if (!(mode & BLK_OPEN_EXCL)) |
1118 | bd_abort_claiming(bdev, holder: loop_configure); |
1119 | |
1120 | return 0; |
1121 | |
1122 | out_unlock: |
1123 | loop_global_unlock(lo, global: is_loop); |
1124 | out_bdev: |
1125 | if (!(mode & BLK_OPEN_EXCL)) |
1126 | bd_abort_claiming(bdev, holder: loop_configure); |
1127 | out_putf: |
1128 | fput(file); |
1129 | /* This is safe: open() is still holding a reference. */ |
1130 | module_put(THIS_MODULE); |
1131 | return error; |
1132 | } |
1133 | |
1134 | static void __loop_clr_fd(struct loop_device *lo, bool release) |
1135 | { |
1136 | struct file *filp; |
1137 | gfp_t gfp = lo->old_gfp_mask; |
1138 | |
1139 | if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags)) |
1140 | blk_queue_write_cache(q: lo->lo_queue, enabled: false, fua: false); |
1141 | |
1142 | /* |
1143 | * Freeze the request queue when unbinding on a live file descriptor and |
1144 | * thus an open device. When called from ->release we are guaranteed |
1145 | * that there is no I/O in progress already. |
1146 | */ |
1147 | if (!release) |
1148 | blk_mq_freeze_queue(q: lo->lo_queue); |
1149 | |
1150 | spin_lock_irq(lock: &lo->lo_lock); |
1151 | filp = lo->lo_backing_file; |
1152 | lo->lo_backing_file = NULL; |
1153 | spin_unlock_irq(lock: &lo->lo_lock); |
1154 | |
1155 | lo->lo_device = NULL; |
1156 | lo->lo_offset = 0; |
1157 | lo->lo_sizelimit = 0; |
1158 | memset(lo->lo_file_name, 0, LO_NAME_SIZE); |
1159 | loop_reconfigure_limits(lo, bsize: 512, update_discard_settings: false); |
1160 | invalidate_disk(disk: lo->lo_disk); |
1161 | loop_sysfs_exit(lo); |
1162 | /* let user-space know about this change */ |
1163 | kobject_uevent(kobj: &disk_to_dev(lo->lo_disk)->kobj, action: KOBJ_CHANGE); |
1164 | mapping_set_gfp_mask(m: filp->f_mapping, mask: gfp); |
1165 | /* This is safe: open() is still holding a reference. */ |
1166 | module_put(THIS_MODULE); |
1167 | if (!release) |
1168 | blk_mq_unfreeze_queue(q: lo->lo_queue); |
1169 | |
1170 | disk_force_media_change(disk: lo->lo_disk); |
1171 | |
1172 | if (lo->lo_flags & LO_FLAGS_PARTSCAN) { |
1173 | int err; |
1174 | |
1175 | /* |
1176 | * open_mutex has been held already in release path, so don't |
1177 | * acquire it if this function is called in such case. |
1178 | * |
1179 | * If the reread partition isn't from release path, lo_refcnt |
1180 | * must be at least one and it can only become zero when the |
1181 | * current holder is released. |
1182 | */ |
1183 | if (!release) |
1184 | mutex_lock(&lo->lo_disk->open_mutex); |
1185 | err = bdev_disk_changed(disk: lo->lo_disk, invalidate: false); |
1186 | if (!release) |
1187 | mutex_unlock(lock: &lo->lo_disk->open_mutex); |
1188 | if (err) |
1189 | pr_warn("%s: partition scan of loop%d failed (rc=%d)\n" , |
1190 | __func__, lo->lo_number, err); |
1191 | /* Device is gone, no point in returning error */ |
1192 | } |
1193 | |
1194 | /* |
1195 | * lo->lo_state is set to Lo_unbound here after above partscan has |
1196 | * finished. There cannot be anybody else entering __loop_clr_fd() as |
1197 | * Lo_rundown state protects us from all the other places trying to |
1198 | * change the 'lo' device. |
1199 | */ |
1200 | lo->lo_flags = 0; |
1201 | if (!part_shift) |
1202 | set_bit(GD_SUPPRESS_PART_SCAN, addr: &lo->lo_disk->state); |
1203 | mutex_lock(&lo->lo_mutex); |
1204 | lo->lo_state = Lo_unbound; |
1205 | mutex_unlock(lock: &lo->lo_mutex); |
1206 | |
1207 | /* |
1208 | * Need not hold lo_mutex to fput backing file. Calling fput holding |
1209 | * lo_mutex triggers a circular lock dependency possibility warning as |
1210 | * fput can take open_mutex which is usually taken before lo_mutex. |
1211 | */ |
1212 | fput(filp); |
1213 | } |
1214 | |
1215 | static int loop_clr_fd(struct loop_device *lo) |
1216 | { |
1217 | int err; |
1218 | |
1219 | /* |
1220 | * Since lo_ioctl() is called without locks held, it is possible that |
1221 | * loop_configure()/loop_change_fd() and loop_clr_fd() run in parallel. |
1222 | * |
1223 | * Therefore, use global lock when setting Lo_rundown state in order to |
1224 | * make sure that loop_validate_file() will fail if the "struct file" |
1225 | * which loop_configure()/loop_change_fd() found via fget() was this |
1226 | * loop device. |
1227 | */ |
1228 | err = loop_global_lock_killable(lo, global: true); |
1229 | if (err) |
1230 | return err; |
1231 | if (lo->lo_state != Lo_bound) { |
1232 | loop_global_unlock(lo, global: true); |
1233 | return -ENXIO; |
1234 | } |
1235 | /* |
1236 | * If we've explicitly asked to tear down the loop device, |
1237 | * and it has an elevated reference count, set it for auto-teardown when |
1238 | * the last reference goes away. This stops $!~#$@ udev from |
1239 | * preventing teardown because it decided that it needs to run blkid on |
1240 | * the loopback device whenever they appear. xfstests is notorious for |
1241 | * failing tests because blkid via udev races with a losetup |
1242 | * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d |
1243 | * command to fail with EBUSY. |
1244 | */ |
1245 | if (disk_openers(disk: lo->lo_disk) > 1) { |
1246 | lo->lo_flags |= LO_FLAGS_AUTOCLEAR; |
1247 | loop_global_unlock(lo, global: true); |
1248 | return 0; |
1249 | } |
1250 | lo->lo_state = Lo_rundown; |
1251 | loop_global_unlock(lo, global: true); |
1252 | |
1253 | __loop_clr_fd(lo, release: false); |
1254 | return 0; |
1255 | } |
1256 | |
1257 | static int |
1258 | loop_set_status(struct loop_device *lo, const struct loop_info64 *info) |
1259 | { |
1260 | int err; |
1261 | int prev_lo_flags; |
1262 | bool partscan = false; |
1263 | bool size_changed = false; |
1264 | |
1265 | err = mutex_lock_killable(&lo->lo_mutex); |
1266 | if (err) |
1267 | return err; |
1268 | if (lo->lo_state != Lo_bound) { |
1269 | err = -ENXIO; |
1270 | goto out_unlock; |
1271 | } |
1272 | |
1273 | if (lo->lo_offset != info->lo_offset || |
1274 | lo->lo_sizelimit != info->lo_sizelimit) { |
1275 | size_changed = true; |
1276 | sync_blockdev(bdev: lo->lo_device); |
1277 | invalidate_bdev(bdev: lo->lo_device); |
1278 | } |
1279 | |
1280 | /* I/O need to be drained during transfer transition */ |
1281 | blk_mq_freeze_queue(q: lo->lo_queue); |
1282 | |
1283 | prev_lo_flags = lo->lo_flags; |
1284 | |
1285 | err = loop_set_status_from_info(lo, info); |
1286 | if (err) |
1287 | goto out_unfreeze; |
1288 | |
1289 | /* Mask out flags that can't be set using LOOP_SET_STATUS. */ |
1290 | lo->lo_flags &= LOOP_SET_STATUS_SETTABLE_FLAGS; |
1291 | /* For those flags, use the previous values instead */ |
1292 | lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_SETTABLE_FLAGS; |
1293 | /* For flags that can't be cleared, use previous values too */ |
1294 | lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_CLEARABLE_FLAGS; |
1295 | |
1296 | if (size_changed) { |
1297 | loff_t new_size = get_size(offset: lo->lo_offset, sizelimit: lo->lo_sizelimit, |
1298 | file: lo->lo_backing_file); |
1299 | loop_set_size(lo, size: new_size); |
1300 | } |
1301 | |
1302 | /* update dio if lo_offset or transfer is changed */ |
1303 | __loop_update_dio(lo, dio: lo->use_dio); |
1304 | |
1305 | out_unfreeze: |
1306 | blk_mq_unfreeze_queue(q: lo->lo_queue); |
1307 | |
1308 | if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) && |
1309 | !(prev_lo_flags & LO_FLAGS_PARTSCAN)) { |
1310 | clear_bit(GD_SUPPRESS_PART_SCAN, addr: &lo->lo_disk->state); |
1311 | partscan = true; |
1312 | } |
1313 | out_unlock: |
1314 | mutex_unlock(lock: &lo->lo_mutex); |
1315 | if (partscan) |
1316 | loop_reread_partitions(lo); |
1317 | |
1318 | return err; |
1319 | } |
1320 | |
1321 | static int |
1322 | loop_get_status(struct loop_device *lo, struct loop_info64 *info) |
1323 | { |
1324 | struct path path; |
1325 | struct kstat stat; |
1326 | int ret; |
1327 | |
1328 | ret = mutex_lock_killable(&lo->lo_mutex); |
1329 | if (ret) |
1330 | return ret; |
1331 | if (lo->lo_state != Lo_bound) { |
1332 | mutex_unlock(lock: &lo->lo_mutex); |
1333 | return -ENXIO; |
1334 | } |
1335 | |
1336 | memset(info, 0, sizeof(*info)); |
1337 | info->lo_number = lo->lo_number; |
1338 | info->lo_offset = lo->lo_offset; |
1339 | info->lo_sizelimit = lo->lo_sizelimit; |
1340 | info->lo_flags = lo->lo_flags; |
1341 | memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE); |
1342 | |
1343 | /* Drop lo_mutex while we call into the filesystem. */ |
1344 | path = lo->lo_backing_file->f_path; |
1345 | path_get(&path); |
1346 | mutex_unlock(lock: &lo->lo_mutex); |
1347 | ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT); |
1348 | if (!ret) { |
1349 | info->lo_device = huge_encode_dev(dev: stat.dev); |
1350 | info->lo_inode = stat.ino; |
1351 | info->lo_rdevice = huge_encode_dev(dev: stat.rdev); |
1352 | } |
1353 | path_put(&path); |
1354 | return ret; |
1355 | } |
1356 | |
1357 | static void |
1358 | loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64) |
1359 | { |
1360 | memset(info64, 0, sizeof(*info64)); |
1361 | info64->lo_number = info->lo_number; |
1362 | info64->lo_device = info->lo_device; |
1363 | info64->lo_inode = info->lo_inode; |
1364 | info64->lo_rdevice = info->lo_rdevice; |
1365 | info64->lo_offset = info->lo_offset; |
1366 | info64->lo_sizelimit = 0; |
1367 | info64->lo_flags = info->lo_flags; |
1368 | memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE); |
1369 | } |
1370 | |
1371 | static int |
1372 | loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info) |
1373 | { |
1374 | memset(info, 0, sizeof(*info)); |
1375 | info->lo_number = info64->lo_number; |
1376 | info->lo_device = info64->lo_device; |
1377 | info->lo_inode = info64->lo_inode; |
1378 | info->lo_rdevice = info64->lo_rdevice; |
1379 | info->lo_offset = info64->lo_offset; |
1380 | info->lo_flags = info64->lo_flags; |
1381 | memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE); |
1382 | |
1383 | /* error in case values were truncated */ |
1384 | if (info->lo_device != info64->lo_device || |
1385 | info->lo_rdevice != info64->lo_rdevice || |
1386 | info->lo_inode != info64->lo_inode || |
1387 | info->lo_offset != info64->lo_offset) |
1388 | return -EOVERFLOW; |
1389 | |
1390 | return 0; |
1391 | } |
1392 | |
1393 | static int |
1394 | loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg) |
1395 | { |
1396 | struct loop_info info; |
1397 | struct loop_info64 info64; |
1398 | |
1399 | if (copy_from_user(to: &info, from: arg, n: sizeof (struct loop_info))) |
1400 | return -EFAULT; |
1401 | loop_info64_from_old(info: &info, info64: &info64); |
1402 | return loop_set_status(lo, info: &info64); |
1403 | } |
1404 | |
1405 | static int |
1406 | loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg) |
1407 | { |
1408 | struct loop_info64 info64; |
1409 | |
1410 | if (copy_from_user(to: &info64, from: arg, n: sizeof (struct loop_info64))) |
1411 | return -EFAULT; |
1412 | return loop_set_status(lo, info: &info64); |
1413 | } |
1414 | |
1415 | static int |
1416 | loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) { |
1417 | struct loop_info info; |
1418 | struct loop_info64 info64; |
1419 | int err; |
1420 | |
1421 | if (!arg) |
1422 | return -EINVAL; |
1423 | err = loop_get_status(lo, info: &info64); |
1424 | if (!err) |
1425 | err = loop_info64_to_old(info64: &info64, info: &info); |
1426 | if (!err && copy_to_user(to: arg, from: &info, n: sizeof(info))) |
1427 | err = -EFAULT; |
1428 | |
1429 | return err; |
1430 | } |
1431 | |
1432 | static int |
1433 | loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) { |
1434 | struct loop_info64 info64; |
1435 | int err; |
1436 | |
1437 | if (!arg) |
1438 | return -EINVAL; |
1439 | err = loop_get_status(lo, info: &info64); |
1440 | if (!err && copy_to_user(to: arg, from: &info64, n: sizeof(info64))) |
1441 | err = -EFAULT; |
1442 | |
1443 | return err; |
1444 | } |
1445 | |
1446 | static int loop_set_capacity(struct loop_device *lo) |
1447 | { |
1448 | loff_t size; |
1449 | |
1450 | if (unlikely(lo->lo_state != Lo_bound)) |
1451 | return -ENXIO; |
1452 | |
1453 | size = get_loop_size(lo, file: lo->lo_backing_file); |
1454 | loop_set_size(lo, size); |
1455 | |
1456 | return 0; |
1457 | } |
1458 | |
1459 | static int loop_set_dio(struct loop_device *lo, unsigned long arg) |
1460 | { |
1461 | int error = -ENXIO; |
1462 | if (lo->lo_state != Lo_bound) |
1463 | goto out; |
1464 | |
1465 | __loop_update_dio(lo, dio: !!arg); |
1466 | if (lo->use_dio == !!arg) |
1467 | return 0; |
1468 | error = -EINVAL; |
1469 | out: |
1470 | return error; |
1471 | } |
1472 | |
1473 | static int loop_set_block_size(struct loop_device *lo, unsigned long arg) |
1474 | { |
1475 | int err = 0; |
1476 | |
1477 | if (lo->lo_state != Lo_bound) |
1478 | return -ENXIO; |
1479 | |
1480 | err = blk_validate_block_size(bsize: arg); |
1481 | if (err) |
1482 | return err; |
1483 | |
1484 | if (lo->lo_queue->limits.logical_block_size == arg) |
1485 | return 0; |
1486 | |
1487 | sync_blockdev(bdev: lo->lo_device); |
1488 | invalidate_bdev(bdev: lo->lo_device); |
1489 | |
1490 | blk_mq_freeze_queue(q: lo->lo_queue); |
1491 | err = loop_reconfigure_limits(lo, bsize: arg, update_discard_settings: false); |
1492 | loop_update_dio(lo); |
1493 | blk_mq_unfreeze_queue(q: lo->lo_queue); |
1494 | |
1495 | return err; |
1496 | } |
1497 | |
1498 | static int lo_simple_ioctl(struct loop_device *lo, unsigned int cmd, |
1499 | unsigned long arg) |
1500 | { |
1501 | int err; |
1502 | |
1503 | err = mutex_lock_killable(&lo->lo_mutex); |
1504 | if (err) |
1505 | return err; |
1506 | switch (cmd) { |
1507 | case LOOP_SET_CAPACITY: |
1508 | err = loop_set_capacity(lo); |
1509 | break; |
1510 | case LOOP_SET_DIRECT_IO: |
1511 | err = loop_set_dio(lo, arg); |
1512 | break; |
1513 | case LOOP_SET_BLOCK_SIZE: |
1514 | err = loop_set_block_size(lo, arg); |
1515 | break; |
1516 | default: |
1517 | err = -EINVAL; |
1518 | } |
1519 | mutex_unlock(lock: &lo->lo_mutex); |
1520 | return err; |
1521 | } |
1522 | |
1523 | static int lo_ioctl(struct block_device *bdev, blk_mode_t mode, |
1524 | unsigned int cmd, unsigned long arg) |
1525 | { |
1526 | struct loop_device *lo = bdev->bd_disk->private_data; |
1527 | void __user *argp = (void __user *) arg; |
1528 | int err; |
1529 | |
1530 | switch (cmd) { |
1531 | case LOOP_SET_FD: { |
1532 | /* |
1533 | * Legacy case - pass in a zeroed out struct loop_config with |
1534 | * only the file descriptor set , which corresponds with the |
1535 | * default parameters we'd have used otherwise. |
1536 | */ |
1537 | struct loop_config config; |
1538 | |
1539 | memset(&config, 0, sizeof(config)); |
1540 | config.fd = arg; |
1541 | |
1542 | return loop_configure(lo, mode, bdev, config: &config); |
1543 | } |
1544 | case LOOP_CONFIGURE: { |
1545 | struct loop_config config; |
1546 | |
1547 | if (copy_from_user(to: &config, from: argp, n: sizeof(config))) |
1548 | return -EFAULT; |
1549 | |
1550 | return loop_configure(lo, mode, bdev, config: &config); |
1551 | } |
1552 | case LOOP_CHANGE_FD: |
1553 | return loop_change_fd(lo, bdev, arg); |
1554 | case LOOP_CLR_FD: |
1555 | return loop_clr_fd(lo); |
1556 | case LOOP_SET_STATUS: |
1557 | err = -EPERM; |
1558 | if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN)) |
1559 | err = loop_set_status_old(lo, arg: argp); |
1560 | break; |
1561 | case LOOP_GET_STATUS: |
1562 | return loop_get_status_old(lo, arg: argp); |
1563 | case LOOP_SET_STATUS64: |
1564 | err = -EPERM; |
1565 | if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN)) |
1566 | err = loop_set_status64(lo, arg: argp); |
1567 | break; |
1568 | case LOOP_GET_STATUS64: |
1569 | return loop_get_status64(lo, arg: argp); |
1570 | case LOOP_SET_CAPACITY: |
1571 | case LOOP_SET_DIRECT_IO: |
1572 | case LOOP_SET_BLOCK_SIZE: |
1573 | if (!(mode & BLK_OPEN_WRITE) && !capable(CAP_SYS_ADMIN)) |
1574 | return -EPERM; |
1575 | fallthrough; |
1576 | default: |
1577 | err = lo_simple_ioctl(lo, cmd, arg); |
1578 | break; |
1579 | } |
1580 | |
1581 | return err; |
1582 | } |
1583 | |
1584 | #ifdef CONFIG_COMPAT |
1585 | struct compat_loop_info { |
1586 | compat_int_t lo_number; /* ioctl r/o */ |
1587 | compat_dev_t lo_device; /* ioctl r/o */ |
1588 | compat_ulong_t lo_inode; /* ioctl r/o */ |
1589 | compat_dev_t lo_rdevice; /* ioctl r/o */ |
1590 | compat_int_t lo_offset; |
1591 | compat_int_t lo_encrypt_type; /* obsolete, ignored */ |
1592 | compat_int_t lo_encrypt_key_size; /* ioctl w/o */ |
1593 | compat_int_t lo_flags; /* ioctl r/o */ |
1594 | char lo_name[LO_NAME_SIZE]; |
1595 | unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */ |
1596 | compat_ulong_t lo_init[2]; |
1597 | char reserved[4]; |
1598 | }; |
1599 | |
1600 | /* |
1601 | * Transfer 32-bit compatibility structure in userspace to 64-bit loop info |
1602 | * - noinlined to reduce stack space usage in main part of driver |
1603 | */ |
1604 | static noinline int |
1605 | loop_info64_from_compat(const struct compat_loop_info __user *arg, |
1606 | struct loop_info64 *info64) |
1607 | { |
1608 | struct compat_loop_info info; |
1609 | |
1610 | if (copy_from_user(to: &info, from: arg, n: sizeof(info))) |
1611 | return -EFAULT; |
1612 | |
1613 | memset(info64, 0, sizeof(*info64)); |
1614 | info64->lo_number = info.lo_number; |
1615 | info64->lo_device = info.lo_device; |
1616 | info64->lo_inode = info.lo_inode; |
1617 | info64->lo_rdevice = info.lo_rdevice; |
1618 | info64->lo_offset = info.lo_offset; |
1619 | info64->lo_sizelimit = 0; |
1620 | info64->lo_flags = info.lo_flags; |
1621 | memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE); |
1622 | return 0; |
1623 | } |
1624 | |
1625 | /* |
1626 | * Transfer 64-bit loop info to 32-bit compatibility structure in userspace |
1627 | * - noinlined to reduce stack space usage in main part of driver |
1628 | */ |
1629 | static noinline int |
1630 | loop_info64_to_compat(const struct loop_info64 *info64, |
1631 | struct compat_loop_info __user *arg) |
1632 | { |
1633 | struct compat_loop_info info; |
1634 | |
1635 | memset(&info, 0, sizeof(info)); |
1636 | info.lo_number = info64->lo_number; |
1637 | info.lo_device = info64->lo_device; |
1638 | info.lo_inode = info64->lo_inode; |
1639 | info.lo_rdevice = info64->lo_rdevice; |
1640 | info.lo_offset = info64->lo_offset; |
1641 | info.lo_flags = info64->lo_flags; |
1642 | memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE); |
1643 | |
1644 | /* error in case values were truncated */ |
1645 | if (info.lo_device != info64->lo_device || |
1646 | info.lo_rdevice != info64->lo_rdevice || |
1647 | info.lo_inode != info64->lo_inode || |
1648 | info.lo_offset != info64->lo_offset) |
1649 | return -EOVERFLOW; |
1650 | |
1651 | if (copy_to_user(to: arg, from: &info, n: sizeof(info))) |
1652 | return -EFAULT; |
1653 | return 0; |
1654 | } |
1655 | |
1656 | static int |
1657 | loop_set_status_compat(struct loop_device *lo, |
1658 | const struct compat_loop_info __user *arg) |
1659 | { |
1660 | struct loop_info64 info64; |
1661 | int ret; |
1662 | |
1663 | ret = loop_info64_from_compat(arg, info64: &info64); |
1664 | if (ret < 0) |
1665 | return ret; |
1666 | return loop_set_status(lo, info: &info64); |
1667 | } |
1668 | |
1669 | static int |
1670 | loop_get_status_compat(struct loop_device *lo, |
1671 | struct compat_loop_info __user *arg) |
1672 | { |
1673 | struct loop_info64 info64; |
1674 | int err; |
1675 | |
1676 | if (!arg) |
1677 | return -EINVAL; |
1678 | err = loop_get_status(lo, info: &info64); |
1679 | if (!err) |
1680 | err = loop_info64_to_compat(info64: &info64, arg); |
1681 | return err; |
1682 | } |
1683 | |
1684 | static int lo_compat_ioctl(struct block_device *bdev, blk_mode_t mode, |
1685 | unsigned int cmd, unsigned long arg) |
1686 | { |
1687 | struct loop_device *lo = bdev->bd_disk->private_data; |
1688 | int err; |
1689 | |
1690 | switch(cmd) { |
1691 | case LOOP_SET_STATUS: |
1692 | err = loop_set_status_compat(lo, |
1693 | arg: (const struct compat_loop_info __user *)arg); |
1694 | break; |
1695 | case LOOP_GET_STATUS: |
1696 | err = loop_get_status_compat(lo, |
1697 | arg: (struct compat_loop_info __user *)arg); |
1698 | break; |
1699 | case LOOP_SET_CAPACITY: |
1700 | case LOOP_CLR_FD: |
1701 | case LOOP_GET_STATUS64: |
1702 | case LOOP_SET_STATUS64: |
1703 | case LOOP_CONFIGURE: |
1704 | arg = (unsigned long) compat_ptr(uptr: arg); |
1705 | fallthrough; |
1706 | case LOOP_SET_FD: |
1707 | case LOOP_CHANGE_FD: |
1708 | case LOOP_SET_BLOCK_SIZE: |
1709 | case LOOP_SET_DIRECT_IO: |
1710 | err = lo_ioctl(bdev, mode, cmd, arg); |
1711 | break; |
1712 | default: |
1713 | err = -ENOIOCTLCMD; |
1714 | break; |
1715 | } |
1716 | return err; |
1717 | } |
1718 | #endif |
1719 | |
1720 | static void lo_release(struct gendisk *disk) |
1721 | { |
1722 | struct loop_device *lo = disk->private_data; |
1723 | |
1724 | if (disk_openers(disk) > 0) |
1725 | return; |
1726 | |
1727 | mutex_lock(&lo->lo_mutex); |
1728 | if (lo->lo_state == Lo_bound && (lo->lo_flags & LO_FLAGS_AUTOCLEAR)) { |
1729 | lo->lo_state = Lo_rundown; |
1730 | mutex_unlock(lock: &lo->lo_mutex); |
1731 | /* |
1732 | * In autoclear mode, stop the loop thread |
1733 | * and remove configuration after last close. |
1734 | */ |
1735 | __loop_clr_fd(lo, release: true); |
1736 | return; |
1737 | } |
1738 | mutex_unlock(lock: &lo->lo_mutex); |
1739 | } |
1740 | |
1741 | static void lo_free_disk(struct gendisk *disk) |
1742 | { |
1743 | struct loop_device *lo = disk->private_data; |
1744 | |
1745 | if (lo->workqueue) |
1746 | destroy_workqueue(wq: lo->workqueue); |
1747 | loop_free_idle_workers(lo, delete_all: true); |
1748 | timer_shutdown_sync(timer: &lo->timer); |
1749 | mutex_destroy(lock: &lo->lo_mutex); |
1750 | kfree(objp: lo); |
1751 | } |
1752 | |
1753 | static const struct block_device_operations lo_fops = { |
1754 | .owner = THIS_MODULE, |
1755 | .release = lo_release, |
1756 | .ioctl = lo_ioctl, |
1757 | #ifdef CONFIG_COMPAT |
1758 | .compat_ioctl = lo_compat_ioctl, |
1759 | #endif |
1760 | .free_disk = lo_free_disk, |
1761 | }; |
1762 | |
1763 | /* |
1764 | * And now the modules code and kernel interface. |
1765 | */ |
1766 | |
1767 | /* |
1768 | * If max_loop is specified, create that many devices upfront. |
1769 | * This also becomes a hard limit. If max_loop is not specified, |
1770 | * the default isn't a hard limit (as before commit 85c50197716c |
1771 | * changed the default value from 0 for max_loop=0 reasons), just |
1772 | * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module |
1773 | * init time. Loop devices can be requested on-demand with the |
1774 | * /dev/loop-control interface, or be instantiated by accessing |
1775 | * a 'dead' device node. |
1776 | */ |
1777 | static int max_loop = CONFIG_BLK_DEV_LOOP_MIN_COUNT; |
1778 | |
1779 | #ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD |
1780 | static bool max_loop_specified; |
1781 | |
1782 | static int max_loop_param_set_int(const char *val, |
1783 | const struct kernel_param *kp) |
1784 | { |
1785 | int ret; |
1786 | |
1787 | ret = param_set_int(val, kp); |
1788 | if (ret < 0) |
1789 | return ret; |
1790 | |
1791 | max_loop_specified = true; |
1792 | return 0; |
1793 | } |
1794 | |
1795 | static const struct kernel_param_ops max_loop_param_ops = { |
1796 | .set = max_loop_param_set_int, |
1797 | .get = param_get_int, |
1798 | }; |
1799 | |
1800 | module_param_cb(max_loop, &max_loop_param_ops, &max_loop, 0444); |
1801 | MODULE_PARM_DESC(max_loop, "Maximum number of loop devices" ); |
1802 | #else |
1803 | module_param(max_loop, int, 0444); |
1804 | MODULE_PARM_DESC(max_loop, "Initial number of loop devices" ); |
1805 | #endif |
1806 | |
1807 | module_param(max_part, int, 0444); |
1808 | MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device" ); |
1809 | |
1810 | static int hw_queue_depth = LOOP_DEFAULT_HW_Q_DEPTH; |
1811 | |
1812 | static int loop_set_hw_queue_depth(const char *s, const struct kernel_param *p) |
1813 | { |
1814 | int qd, ret; |
1815 | |
1816 | ret = kstrtoint(s, base: 0, res: &qd); |
1817 | if (ret < 0) |
1818 | return ret; |
1819 | if (qd < 1) |
1820 | return -EINVAL; |
1821 | hw_queue_depth = qd; |
1822 | return 0; |
1823 | } |
1824 | |
1825 | static const struct kernel_param_ops loop_hw_qdepth_param_ops = { |
1826 | .set = loop_set_hw_queue_depth, |
1827 | .get = param_get_int, |
1828 | }; |
1829 | |
1830 | device_param_cb(hw_queue_depth, &loop_hw_qdepth_param_ops, &hw_queue_depth, 0444); |
1831 | MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: " __stringify(LOOP_DEFAULT_HW_Q_DEPTH)); |
1832 | |
1833 | MODULE_LICENSE("GPL" ); |
1834 | MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR); |
1835 | |
1836 | static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx, |
1837 | const struct blk_mq_queue_data *bd) |
1838 | { |
1839 | struct request *rq = bd->rq; |
1840 | struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); |
1841 | struct loop_device *lo = rq->q->queuedata; |
1842 | |
1843 | blk_mq_start_request(rq); |
1844 | |
1845 | if (lo->lo_state != Lo_bound) |
1846 | return BLK_STS_IOERR; |
1847 | |
1848 | switch (req_op(req: rq)) { |
1849 | case REQ_OP_FLUSH: |
1850 | case REQ_OP_DISCARD: |
1851 | case REQ_OP_WRITE_ZEROES: |
1852 | cmd->use_aio = false; |
1853 | break; |
1854 | default: |
1855 | cmd->use_aio = lo->use_dio; |
1856 | break; |
1857 | } |
1858 | |
1859 | /* always use the first bio's css */ |
1860 | cmd->blkcg_css = NULL; |
1861 | cmd->memcg_css = NULL; |
1862 | #ifdef CONFIG_BLK_CGROUP |
1863 | if (rq->bio) { |
1864 | cmd->blkcg_css = bio_blkcg_css(bio: rq->bio); |
1865 | #ifdef CONFIG_MEMCG |
1866 | if (cmd->blkcg_css) { |
1867 | cmd->memcg_css = |
1868 | cgroup_get_e_css(cgroup: cmd->blkcg_css->cgroup, |
1869 | ss: &memory_cgrp_subsys); |
1870 | } |
1871 | #endif |
1872 | } |
1873 | #endif |
1874 | loop_queue_work(lo, cmd); |
1875 | |
1876 | return BLK_STS_OK; |
1877 | } |
1878 | |
1879 | static void loop_handle_cmd(struct loop_cmd *cmd) |
1880 | { |
1881 | struct cgroup_subsys_state *cmd_blkcg_css = cmd->blkcg_css; |
1882 | struct cgroup_subsys_state *cmd_memcg_css = cmd->memcg_css; |
1883 | struct request *rq = blk_mq_rq_from_pdu(pdu: cmd); |
1884 | const bool write = op_is_write(op: req_op(req: rq)); |
1885 | struct loop_device *lo = rq->q->queuedata; |
1886 | int ret = 0; |
1887 | struct mem_cgroup *old_memcg = NULL; |
1888 | const bool use_aio = cmd->use_aio; |
1889 | |
1890 | if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) { |
1891 | ret = -EIO; |
1892 | goto failed; |
1893 | } |
1894 | |
1895 | if (cmd_blkcg_css) |
1896 | kthread_associate_blkcg(css: cmd_blkcg_css); |
1897 | if (cmd_memcg_css) |
1898 | old_memcg = set_active_memcg( |
1899 | mem_cgroup_from_css(css: cmd_memcg_css)); |
1900 | |
1901 | /* |
1902 | * do_req_filebacked() may call blk_mq_complete_request() synchronously |
1903 | * or asynchronously if using aio. Hence, do not touch 'cmd' after |
1904 | * do_req_filebacked() has returned unless we are sure that 'cmd' has |
1905 | * not yet been completed. |
1906 | */ |
1907 | ret = do_req_filebacked(lo, rq); |
1908 | |
1909 | if (cmd_blkcg_css) |
1910 | kthread_associate_blkcg(NULL); |
1911 | |
1912 | if (cmd_memcg_css) { |
1913 | set_active_memcg(old_memcg); |
1914 | css_put(css: cmd_memcg_css); |
1915 | } |
1916 | failed: |
1917 | /* complete non-aio request */ |
1918 | if (!use_aio || ret) { |
1919 | if (ret == -EOPNOTSUPP) |
1920 | cmd->ret = ret; |
1921 | else |
1922 | cmd->ret = ret ? -EIO : 0; |
1923 | if (likely(!blk_should_fake_timeout(rq->q))) |
1924 | blk_mq_complete_request(rq); |
1925 | } |
1926 | } |
1927 | |
1928 | static void loop_process_work(struct loop_worker *worker, |
1929 | struct list_head *cmd_list, struct loop_device *lo) |
1930 | { |
1931 | int orig_flags = current->flags; |
1932 | struct loop_cmd *cmd; |
1933 | |
1934 | current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO; |
1935 | spin_lock_irq(lock: &lo->lo_work_lock); |
1936 | while (!list_empty(head: cmd_list)) { |
1937 | cmd = container_of( |
1938 | cmd_list->next, struct loop_cmd, list_entry); |
1939 | list_del(entry: cmd_list->next); |
1940 | spin_unlock_irq(lock: &lo->lo_work_lock); |
1941 | |
1942 | loop_handle_cmd(cmd); |
1943 | cond_resched(); |
1944 | |
1945 | spin_lock_irq(lock: &lo->lo_work_lock); |
1946 | } |
1947 | |
1948 | /* |
1949 | * We only add to the idle list if there are no pending cmds |
1950 | * *and* the worker will not run again which ensures that it |
1951 | * is safe to free any worker on the idle list |
1952 | */ |
1953 | if (worker && !work_pending(&worker->work)) { |
1954 | worker->last_ran_at = jiffies; |
1955 | list_add_tail(new: &worker->idle_list, head: &lo->idle_worker_list); |
1956 | loop_set_timer(lo); |
1957 | } |
1958 | spin_unlock_irq(lock: &lo->lo_work_lock); |
1959 | current->flags = orig_flags; |
1960 | } |
1961 | |
1962 | static void loop_workfn(struct work_struct *work) |
1963 | { |
1964 | struct loop_worker *worker = |
1965 | container_of(work, struct loop_worker, work); |
1966 | loop_process_work(worker, cmd_list: &worker->cmd_list, lo: worker->lo); |
1967 | } |
1968 | |
1969 | static void loop_rootcg_workfn(struct work_struct *work) |
1970 | { |
1971 | struct loop_device *lo = |
1972 | container_of(work, struct loop_device, rootcg_work); |
1973 | loop_process_work(NULL, cmd_list: &lo->rootcg_cmd_list, lo); |
1974 | } |
1975 | |
1976 | static const struct blk_mq_ops loop_mq_ops = { |
1977 | .queue_rq = loop_queue_rq, |
1978 | .complete = lo_complete_rq, |
1979 | }; |
1980 | |
1981 | static int loop_add(int i) |
1982 | { |
1983 | struct queue_limits lim = { |
1984 | /* |
1985 | * Random number picked from the historic block max_sectors cap. |
1986 | */ |
1987 | .max_hw_sectors = 2560u, |
1988 | }; |
1989 | struct loop_device *lo; |
1990 | struct gendisk *disk; |
1991 | int err; |
1992 | |
1993 | err = -ENOMEM; |
1994 | lo = kzalloc(size: sizeof(*lo), GFP_KERNEL); |
1995 | if (!lo) |
1996 | goto out; |
1997 | lo->worker_tree = RB_ROOT; |
1998 | INIT_LIST_HEAD(list: &lo->idle_worker_list); |
1999 | timer_setup(&lo->timer, loop_free_idle_workers_timer, TIMER_DEFERRABLE); |
2000 | lo->lo_state = Lo_unbound; |
2001 | |
2002 | err = mutex_lock_killable(&loop_ctl_mutex); |
2003 | if (err) |
2004 | goto out_free_dev; |
2005 | |
2006 | /* allocate id, if @id >= 0, we're requesting that specific id */ |
2007 | if (i >= 0) { |
2008 | err = idr_alloc(&loop_index_idr, ptr: lo, start: i, end: i + 1, GFP_KERNEL); |
2009 | if (err == -ENOSPC) |
2010 | err = -EEXIST; |
2011 | } else { |
2012 | err = idr_alloc(&loop_index_idr, ptr: lo, start: 0, end: 0, GFP_KERNEL); |
2013 | } |
2014 | mutex_unlock(lock: &loop_ctl_mutex); |
2015 | if (err < 0) |
2016 | goto out_free_dev; |
2017 | i = err; |
2018 | |
2019 | lo->tag_set.ops = &loop_mq_ops; |
2020 | lo->tag_set.nr_hw_queues = 1; |
2021 | lo->tag_set.queue_depth = hw_queue_depth; |
2022 | lo->tag_set.numa_node = NUMA_NO_NODE; |
2023 | lo->tag_set.cmd_size = sizeof(struct loop_cmd); |
2024 | lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING | |
2025 | BLK_MQ_F_NO_SCHED_BY_DEFAULT; |
2026 | lo->tag_set.driver_data = lo; |
2027 | |
2028 | err = blk_mq_alloc_tag_set(set: &lo->tag_set); |
2029 | if (err) |
2030 | goto out_free_idr; |
2031 | |
2032 | disk = lo->lo_disk = blk_mq_alloc_disk(&lo->tag_set, &lim, lo); |
2033 | if (IS_ERR(ptr: disk)) { |
2034 | err = PTR_ERR(ptr: disk); |
2035 | goto out_cleanup_tags; |
2036 | } |
2037 | lo->lo_queue = lo->lo_disk->queue; |
2038 | |
2039 | /* |
2040 | * By default, we do buffer IO, so it doesn't make sense to enable |
2041 | * merge because the I/O submitted to backing file is handled page by |
2042 | * page. For directio mode, merge does help to dispatch bigger request |
2043 | * to underlayer disk. We will enable merge once directio is enabled. |
2044 | */ |
2045 | blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q: lo->lo_queue); |
2046 | |
2047 | /* |
2048 | * Disable partition scanning by default. The in-kernel partition |
2049 | * scanning can be requested individually per-device during its |
2050 | * setup. Userspace can always add and remove partitions from all |
2051 | * devices. The needed partition minors are allocated from the |
2052 | * extended minor space, the main loop device numbers will continue |
2053 | * to match the loop minors, regardless of the number of partitions |
2054 | * used. |
2055 | * |
2056 | * If max_part is given, partition scanning is globally enabled for |
2057 | * all loop devices. The minors for the main loop devices will be |
2058 | * multiples of max_part. |
2059 | * |
2060 | * Note: Global-for-all-devices, set-only-at-init, read-only module |
2061 | * parameteters like 'max_loop' and 'max_part' make things needlessly |
2062 | * complicated, are too static, inflexible and may surprise |
2063 | * userspace tools. Parameters like this in general should be avoided. |
2064 | */ |
2065 | if (!part_shift) |
2066 | set_bit(GD_SUPPRESS_PART_SCAN, addr: &disk->state); |
2067 | mutex_init(&lo->lo_mutex); |
2068 | lo->lo_number = i; |
2069 | spin_lock_init(&lo->lo_lock); |
2070 | spin_lock_init(&lo->lo_work_lock); |
2071 | INIT_WORK(&lo->rootcg_work, loop_rootcg_workfn); |
2072 | INIT_LIST_HEAD(list: &lo->rootcg_cmd_list); |
2073 | disk->major = LOOP_MAJOR; |
2074 | disk->first_minor = i << part_shift; |
2075 | disk->minors = 1 << part_shift; |
2076 | disk->fops = &lo_fops; |
2077 | disk->private_data = lo; |
2078 | disk->queue = lo->lo_queue; |
2079 | disk->events = DISK_EVENT_MEDIA_CHANGE; |
2080 | disk->event_flags = DISK_EVENT_FLAG_UEVENT; |
2081 | sprintf(buf: disk->disk_name, fmt: "loop%d" , i); |
2082 | /* Make this loop device reachable from pathname. */ |
2083 | err = add_disk(disk); |
2084 | if (err) |
2085 | goto out_cleanup_disk; |
2086 | |
2087 | /* Show this loop device. */ |
2088 | mutex_lock(&loop_ctl_mutex); |
2089 | lo->idr_visible = true; |
2090 | mutex_unlock(lock: &loop_ctl_mutex); |
2091 | |
2092 | return i; |
2093 | |
2094 | out_cleanup_disk: |
2095 | put_disk(disk); |
2096 | out_cleanup_tags: |
2097 | blk_mq_free_tag_set(set: &lo->tag_set); |
2098 | out_free_idr: |
2099 | mutex_lock(&loop_ctl_mutex); |
2100 | idr_remove(&loop_index_idr, id: i); |
2101 | mutex_unlock(lock: &loop_ctl_mutex); |
2102 | out_free_dev: |
2103 | kfree(objp: lo); |
2104 | out: |
2105 | return err; |
2106 | } |
2107 | |
2108 | static void loop_remove(struct loop_device *lo) |
2109 | { |
2110 | /* Make this loop device unreachable from pathname. */ |
2111 | del_gendisk(gp: lo->lo_disk); |
2112 | blk_mq_free_tag_set(set: &lo->tag_set); |
2113 | |
2114 | mutex_lock(&loop_ctl_mutex); |
2115 | idr_remove(&loop_index_idr, id: lo->lo_number); |
2116 | mutex_unlock(lock: &loop_ctl_mutex); |
2117 | |
2118 | put_disk(disk: lo->lo_disk); |
2119 | } |
2120 | |
2121 | #ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD |
2122 | static void loop_probe(dev_t dev) |
2123 | { |
2124 | int idx = MINOR(dev) >> part_shift; |
2125 | |
2126 | if (max_loop_specified && max_loop && idx >= max_loop) |
2127 | return; |
2128 | loop_add(i: idx); |
2129 | } |
2130 | #else |
2131 | #define loop_probe NULL |
2132 | #endif /* !CONFIG_BLOCK_LEGACY_AUTOLOAD */ |
2133 | |
2134 | static int loop_control_remove(int idx) |
2135 | { |
2136 | struct loop_device *lo; |
2137 | int ret; |
2138 | |
2139 | if (idx < 0) { |
2140 | pr_warn_once("deleting an unspecified loop device is not supported.\n" ); |
2141 | return -EINVAL; |
2142 | } |
2143 | |
2144 | /* Hide this loop device for serialization. */ |
2145 | ret = mutex_lock_killable(&loop_ctl_mutex); |
2146 | if (ret) |
2147 | return ret; |
2148 | lo = idr_find(&loop_index_idr, id: idx); |
2149 | if (!lo || !lo->idr_visible) |
2150 | ret = -ENODEV; |
2151 | else |
2152 | lo->idr_visible = false; |
2153 | mutex_unlock(lock: &loop_ctl_mutex); |
2154 | if (ret) |
2155 | return ret; |
2156 | |
2157 | /* Check whether this loop device can be removed. */ |
2158 | ret = mutex_lock_killable(&lo->lo_mutex); |
2159 | if (ret) |
2160 | goto mark_visible; |
2161 | if (lo->lo_state != Lo_unbound || disk_openers(disk: lo->lo_disk) > 0) { |
2162 | mutex_unlock(lock: &lo->lo_mutex); |
2163 | ret = -EBUSY; |
2164 | goto mark_visible; |
2165 | } |
2166 | /* Mark this loop device as no more bound, but not quite unbound yet */ |
2167 | lo->lo_state = Lo_deleting; |
2168 | mutex_unlock(lock: &lo->lo_mutex); |
2169 | |
2170 | loop_remove(lo); |
2171 | return 0; |
2172 | |
2173 | mark_visible: |
2174 | /* Show this loop device again. */ |
2175 | mutex_lock(&loop_ctl_mutex); |
2176 | lo->idr_visible = true; |
2177 | mutex_unlock(lock: &loop_ctl_mutex); |
2178 | return ret; |
2179 | } |
2180 | |
2181 | static int loop_control_get_free(int idx) |
2182 | { |
2183 | struct loop_device *lo; |
2184 | int id, ret; |
2185 | |
2186 | ret = mutex_lock_killable(&loop_ctl_mutex); |
2187 | if (ret) |
2188 | return ret; |
2189 | idr_for_each_entry(&loop_index_idr, lo, id) { |
2190 | /* Hitting a race results in creating a new loop device which is harmless. */ |
2191 | if (lo->idr_visible && data_race(lo->lo_state) == Lo_unbound) |
2192 | goto found; |
2193 | } |
2194 | mutex_unlock(lock: &loop_ctl_mutex); |
2195 | return loop_add(i: -1); |
2196 | found: |
2197 | mutex_unlock(lock: &loop_ctl_mutex); |
2198 | return id; |
2199 | } |
2200 | |
2201 | static long loop_control_ioctl(struct file *file, unsigned int cmd, |
2202 | unsigned long parm) |
2203 | { |
2204 | switch (cmd) { |
2205 | case LOOP_CTL_ADD: |
2206 | return loop_add(i: parm); |
2207 | case LOOP_CTL_REMOVE: |
2208 | return loop_control_remove(idx: parm); |
2209 | case LOOP_CTL_GET_FREE: |
2210 | return loop_control_get_free(idx: parm); |
2211 | default: |
2212 | return -ENOSYS; |
2213 | } |
2214 | } |
2215 | |
2216 | static const struct file_operations loop_ctl_fops = { |
2217 | .open = nonseekable_open, |
2218 | .unlocked_ioctl = loop_control_ioctl, |
2219 | .compat_ioctl = loop_control_ioctl, |
2220 | .owner = THIS_MODULE, |
2221 | .llseek = noop_llseek, |
2222 | }; |
2223 | |
2224 | static struct miscdevice loop_misc = { |
2225 | .minor = LOOP_CTRL_MINOR, |
2226 | .name = "loop-control" , |
2227 | .fops = &loop_ctl_fops, |
2228 | }; |
2229 | |
2230 | MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR); |
2231 | MODULE_ALIAS("devname:loop-control" ); |
2232 | |
2233 | static int __init loop_init(void) |
2234 | { |
2235 | int i; |
2236 | int err; |
2237 | |
2238 | part_shift = 0; |
2239 | if (max_part > 0) { |
2240 | part_shift = fls(x: max_part); |
2241 | |
2242 | /* |
2243 | * Adjust max_part according to part_shift as it is exported |
2244 | * to user space so that user can decide correct minor number |
2245 | * if [s]he want to create more devices. |
2246 | * |
2247 | * Note that -1 is required because partition 0 is reserved |
2248 | * for the whole disk. |
2249 | */ |
2250 | max_part = (1UL << part_shift) - 1; |
2251 | } |
2252 | |
2253 | if ((1UL << part_shift) > DISK_MAX_PARTS) { |
2254 | err = -EINVAL; |
2255 | goto err_out; |
2256 | } |
2257 | |
2258 | if (max_loop > 1UL << (MINORBITS - part_shift)) { |
2259 | err = -EINVAL; |
2260 | goto err_out; |
2261 | } |
2262 | |
2263 | err = misc_register(misc: &loop_misc); |
2264 | if (err < 0) |
2265 | goto err_out; |
2266 | |
2267 | |
2268 | if (__register_blkdev(LOOP_MAJOR, name: "loop" , probe: loop_probe)) { |
2269 | err = -EIO; |
2270 | goto misc_out; |
2271 | } |
2272 | |
2273 | /* pre-create number of devices given by config or max_loop */ |
2274 | for (i = 0; i < max_loop; i++) |
2275 | loop_add(i); |
2276 | |
2277 | printk(KERN_INFO "loop: module loaded\n" ); |
2278 | return 0; |
2279 | |
2280 | misc_out: |
2281 | misc_deregister(misc: &loop_misc); |
2282 | err_out: |
2283 | return err; |
2284 | } |
2285 | |
2286 | static void __exit loop_exit(void) |
2287 | { |
2288 | struct loop_device *lo; |
2289 | int id; |
2290 | |
2291 | unregister_blkdev(LOOP_MAJOR, name: "loop" ); |
2292 | misc_deregister(misc: &loop_misc); |
2293 | |
2294 | /* |
2295 | * There is no need to use loop_ctl_mutex here, for nobody else can |
2296 | * access loop_index_idr when this module is unloading (unless forced |
2297 | * module unloading is requested). If this is not a clean unloading, |
2298 | * we have no means to avoid kernel crash. |
2299 | */ |
2300 | idr_for_each_entry(&loop_index_idr, lo, id) |
2301 | loop_remove(lo); |
2302 | |
2303 | idr_destroy(&loop_index_idr); |
2304 | } |
2305 | |
2306 | module_init(loop_init); |
2307 | module_exit(loop_exit); |
2308 | |
2309 | #ifndef MODULE |
2310 | static int __init max_loop_setup(char *str) |
2311 | { |
2312 | max_loop = simple_strtol(str, NULL, 0); |
2313 | #ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD |
2314 | max_loop_specified = true; |
2315 | #endif |
2316 | return 1; |
2317 | } |
2318 | |
2319 | __setup("max_loop=" , max_loop_setup); |
2320 | #endif |
2321 | |