xref: /linux/fs/cachefiles/daemon.c (revision ae22a94997b8a03dcb3c922857c203246711f9d4) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Daemon interface
3  *
4  * Copyright (C) 2007, 2021 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  */
7 
8 #include <linux/module.h>
9 #include <linux/init.h>
10 #include <linux/sched.h>
11 #include <linux/completion.h>
12 #include <linux/slab.h>
13 #include <linux/fs.h>
14 #include <linux/file.h>
15 #include <linux/namei.h>
16 #include <linux/poll.h>
17 #include <linux/mount.h>
18 #include <linux/statfs.h>
19 #include <linux/ctype.h>
20 #include <linux/string.h>
21 #include <linux/fs_struct.h>
22 #include "internal.h"
23 
24 static int cachefiles_daemon_open(struct inode *, struct file *);
25 static int cachefiles_daemon_release(struct inode *, struct file *);
26 static ssize_t cachefiles_daemon_read(struct file *, char __user *, size_t,
27 				      loff_t *);
28 static ssize_t cachefiles_daemon_write(struct file *, const char __user *,
29 				       size_t, loff_t *);
30 static __poll_t cachefiles_daemon_poll(struct file *,
31 					   struct poll_table_struct *);
32 static int cachefiles_daemon_frun(struct cachefiles_cache *, char *);
33 static int cachefiles_daemon_fcull(struct cachefiles_cache *, char *);
34 static int cachefiles_daemon_fstop(struct cachefiles_cache *, char *);
35 static int cachefiles_daemon_brun(struct cachefiles_cache *, char *);
36 static int cachefiles_daemon_bcull(struct cachefiles_cache *, char *);
37 static int cachefiles_daemon_bstop(struct cachefiles_cache *, char *);
38 static int cachefiles_daemon_cull(struct cachefiles_cache *, char *);
39 static int cachefiles_daemon_debug(struct cachefiles_cache *, char *);
40 static int cachefiles_daemon_dir(struct cachefiles_cache *, char *);
41 static int cachefiles_daemon_inuse(struct cachefiles_cache *, char *);
42 static int cachefiles_daemon_secctx(struct cachefiles_cache *, char *);
43 static int cachefiles_daemon_tag(struct cachefiles_cache *, char *);
44 static int cachefiles_daemon_bind(struct cachefiles_cache *, char *);
45 static void cachefiles_daemon_unbind(struct cachefiles_cache *);
46 
47 static unsigned long cachefiles_open;
48 
49 const struct file_operations cachefiles_daemon_fops = {
50 	.owner		= THIS_MODULE,
51 	.open		= cachefiles_daemon_open,
52 	.release	= cachefiles_daemon_release,
53 	.read		= cachefiles_daemon_read,
54 	.write		= cachefiles_daemon_write,
55 	.poll		= cachefiles_daemon_poll,
56 	.llseek		= noop_llseek,
57 };
58 
59 struct cachefiles_daemon_cmd {
60 	char name[8];
61 	int (*handler)(struct cachefiles_cache *cache, char *args);
62 };
63 
64 static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = {
65 	{ "bind",	cachefiles_daemon_bind		},
66 	{ "brun",	cachefiles_daemon_brun		},
67 	{ "bcull",	cachefiles_daemon_bcull		},
68 	{ "bstop",	cachefiles_daemon_bstop		},
69 	{ "cull",	cachefiles_daemon_cull		},
70 	{ "debug",	cachefiles_daemon_debug		},
71 	{ "dir",	cachefiles_daemon_dir		},
72 	{ "frun",	cachefiles_daemon_frun		},
73 	{ "fcull",	cachefiles_daemon_fcull		},
74 	{ "fstop",	cachefiles_daemon_fstop		},
75 	{ "inuse",	cachefiles_daemon_inuse		},
76 	{ "secctx",	cachefiles_daemon_secctx	},
77 	{ "tag",	cachefiles_daemon_tag		},
78 #ifdef CONFIG_CACHEFILES_ONDEMAND
79 	{ "copen",	cachefiles_ondemand_copen	},
80 	{ "restore",	cachefiles_ondemand_restore	},
81 #endif
82 	{ "",		NULL				}
83 };
84 
85 
86 /*
87  * Prepare a cache for caching.
88  */
89 static int cachefiles_daemon_open(struct inode *inode, struct file *file)
90 {
91 	struct cachefiles_cache *cache;
92 
93 	_enter("");
94 
95 	/* only the superuser may do this */
96 	if (!capable(CAP_SYS_ADMIN))
97 		return -EPERM;
98 
99 	/* the cachefiles device may only be open once at a time */
100 	if (xchg(&cachefiles_open, 1) == 1)
101 		return -EBUSY;
102 
103 	/* allocate a cache record */
104 	cache = kzalloc(sizeof(struct cachefiles_cache), GFP_KERNEL);
105 	if (!cache) {
106 		cachefiles_open = 0;
107 		return -ENOMEM;
108 	}
109 
110 	mutex_init(&cache->daemon_mutex);
111 	init_waitqueue_head(&cache->daemon_pollwq);
112 	INIT_LIST_HEAD(&cache->volumes);
113 	INIT_LIST_HEAD(&cache->object_list);
114 	spin_lock_init(&cache->object_list_lock);
115 	refcount_set(&cache->unbind_pincount, 1);
116 	xa_init_flags(&cache->reqs, XA_FLAGS_ALLOC);
117 	xa_init_flags(&cache->ondemand_ids, XA_FLAGS_ALLOC1);
118 
119 	/* set default caching limits
120 	 * - limit at 1% free space and/or free files
121 	 * - cull below 5% free space and/or free files
122 	 * - cease culling above 7% free space and/or free files
123 	 */
124 	cache->frun_percent = 7;
125 	cache->fcull_percent = 5;
126 	cache->fstop_percent = 1;
127 	cache->brun_percent = 7;
128 	cache->bcull_percent = 5;
129 	cache->bstop_percent = 1;
130 
131 	file->private_data = cache;
132 	cache->cachefilesd = file;
133 	return 0;
134 }
135 
136 static void cachefiles_flush_reqs(struct cachefiles_cache *cache)
137 {
138 	struct xarray *xa = &cache->reqs;
139 	struct cachefiles_req *req;
140 	unsigned long index;
141 
142 	/*
143 	 * Make sure the following two operations won't be reordered.
144 	 *   1) set CACHEFILES_DEAD bit
145 	 *   2) flush requests in the xarray
146 	 * Otherwise the request may be enqueued after xarray has been
147 	 * flushed, leaving the orphan request never being completed.
148 	 *
149 	 * CPU 1			CPU 2
150 	 * =====			=====
151 	 * flush requests in the xarray
152 	 *				test CACHEFILES_DEAD bit
153 	 *				enqueue the request
154 	 * set CACHEFILES_DEAD bit
155 	 */
156 	smp_mb();
157 
158 	xa_lock(xa);
159 	xa_for_each(xa, index, req) {
160 		req->error = -EIO;
161 		complete(&req->done);
162 	}
163 	xa_unlock(xa);
164 
165 	xa_destroy(&cache->reqs);
166 	xa_destroy(&cache->ondemand_ids);
167 }
168 
169 void cachefiles_put_unbind_pincount(struct cachefiles_cache *cache)
170 {
171 	if (refcount_dec_and_test(&cache->unbind_pincount)) {
172 		cachefiles_daemon_unbind(cache);
173 		cachefiles_open = 0;
174 		kfree(cache);
175 	}
176 }
177 
178 void cachefiles_get_unbind_pincount(struct cachefiles_cache *cache)
179 {
180 	refcount_inc(&cache->unbind_pincount);
181 }
182 
183 /*
184  * Release a cache.
185  */
186 static int cachefiles_daemon_release(struct inode *inode, struct file *file)
187 {
188 	struct cachefiles_cache *cache = file->private_data;
189 
190 	_enter("");
191 
192 	ASSERT(cache);
193 
194 	set_bit(CACHEFILES_DEAD, &cache->flags);
195 
196 	if (cachefiles_in_ondemand_mode(cache))
197 		cachefiles_flush_reqs(cache);
198 
199 	/* clean up the control file interface */
200 	cache->cachefilesd = NULL;
201 	file->private_data = NULL;
202 
203 	cachefiles_put_unbind_pincount(cache);
204 
205 	_leave("");
206 	return 0;
207 }
208 
209 static ssize_t cachefiles_do_daemon_read(struct cachefiles_cache *cache,
210 					 char __user *_buffer, size_t buflen)
211 {
212 	unsigned long long b_released;
213 	unsigned f_released;
214 	char buffer[256];
215 	int n;
216 
217 	/* check how much space the cache has */
218 	cachefiles_has_space(cache, 0, 0, cachefiles_has_space_check);
219 
220 	/* summarise */
221 	f_released = atomic_xchg(&cache->f_released, 0);
222 	b_released = atomic_long_xchg(&cache->b_released, 0);
223 	clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
224 
225 	n = snprintf(buffer, sizeof(buffer),
226 		     "cull=%c"
227 		     " frun=%llx"
228 		     " fcull=%llx"
229 		     " fstop=%llx"
230 		     " brun=%llx"
231 		     " bcull=%llx"
232 		     " bstop=%llx"
233 		     " freleased=%x"
234 		     " breleased=%llx",
235 		     test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
236 		     (unsigned long long) cache->frun,
237 		     (unsigned long long) cache->fcull,
238 		     (unsigned long long) cache->fstop,
239 		     (unsigned long long) cache->brun,
240 		     (unsigned long long) cache->bcull,
241 		     (unsigned long long) cache->bstop,
242 		     f_released,
243 		     b_released);
244 
245 	if (n > buflen)
246 		return -EMSGSIZE;
247 
248 	if (copy_to_user(_buffer, buffer, n) != 0)
249 		return -EFAULT;
250 
251 	return n;
252 }
253 
254 /*
255  * Read the cache state.
256  */
257 static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
258 				      size_t buflen, loff_t *pos)
259 {
260 	struct cachefiles_cache *cache = file->private_data;
261 
262 	//_enter(",,%zu,", buflen);
263 
264 	if (!test_bit(CACHEFILES_READY, &cache->flags))
265 		return 0;
266 
267 	if (cachefiles_in_ondemand_mode(cache))
268 		return cachefiles_ondemand_daemon_read(cache, _buffer, buflen);
269 	else
270 		return cachefiles_do_daemon_read(cache, _buffer, buflen);
271 }
272 
273 /*
274  * Take a command from cachefilesd, parse it and act on it.
275  */
276 static ssize_t cachefiles_daemon_write(struct file *file,
277 				       const char __user *_data,
278 				       size_t datalen,
279 				       loff_t *pos)
280 {
281 	const struct cachefiles_daemon_cmd *cmd;
282 	struct cachefiles_cache *cache = file->private_data;
283 	ssize_t ret;
284 	char *data, *args, *cp;
285 
286 	//_enter(",,%zu,", datalen);
287 
288 	ASSERT(cache);
289 
290 	if (test_bit(CACHEFILES_DEAD, &cache->flags))
291 		return -EIO;
292 
293 	if (datalen > PAGE_SIZE - 1)
294 		return -EOPNOTSUPP;
295 
296 	/* drag the command string into the kernel so we can parse it */
297 	data = memdup_user_nul(_data, datalen);
298 	if (IS_ERR(data))
299 		return PTR_ERR(data);
300 
301 	ret = -EINVAL;
302 	if (memchr(data, '\0', datalen))
303 		goto error;
304 
305 	/* strip any newline */
306 	cp = memchr(data, '\n', datalen);
307 	if (cp) {
308 		if (cp == data)
309 			goto error;
310 
311 		*cp = '\0';
312 	}
313 
314 	/* parse the command */
315 	ret = -EOPNOTSUPP;
316 
317 	for (args = data; *args; args++)
318 		if (isspace(*args))
319 			break;
320 	if (*args) {
321 		if (args == data)
322 			goto error;
323 		*args = '\0';
324 		args = skip_spaces(++args);
325 	}
326 
327 	/* run the appropriate command handler */
328 	for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
329 		if (strcmp(cmd->name, data) == 0)
330 			goto found_command;
331 
332 error:
333 	kfree(data);
334 	//_leave(" = %zd", ret);
335 	return ret;
336 
337 found_command:
338 	mutex_lock(&cache->daemon_mutex);
339 
340 	ret = -EIO;
341 	if (!test_bit(CACHEFILES_DEAD, &cache->flags))
342 		ret = cmd->handler(cache, args);
343 
344 	mutex_unlock(&cache->daemon_mutex);
345 
346 	if (ret == 0)
347 		ret = datalen;
348 	goto error;
349 }
350 
351 /*
352  * Poll for culling state
353  * - use EPOLLOUT to indicate culling state
354  */
355 static __poll_t cachefiles_daemon_poll(struct file *file,
356 					   struct poll_table_struct *poll)
357 {
358 	struct cachefiles_cache *cache = file->private_data;
359 	XA_STATE(xas, &cache->reqs, 0);
360 	struct cachefiles_req *req;
361 	__poll_t mask;
362 
363 	poll_wait(file, &cache->daemon_pollwq, poll);
364 	mask = 0;
365 
366 	if (cachefiles_in_ondemand_mode(cache)) {
367 		if (!xa_empty(&cache->reqs)) {
368 			rcu_read_lock();
369 			xas_for_each_marked(&xas, req, ULONG_MAX, CACHEFILES_REQ_NEW) {
370 				if (!cachefiles_ondemand_is_reopening_read(req)) {
371 					mask |= EPOLLIN;
372 					break;
373 				}
374 			}
375 			rcu_read_unlock();
376 		}
377 	} else {
378 		if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
379 			mask |= EPOLLIN;
380 	}
381 
382 	if (test_bit(CACHEFILES_CULLING, &cache->flags))
383 		mask |= EPOLLOUT;
384 
385 	return mask;
386 }
387 
388 /*
389  * Give a range error for cache space constraints
390  * - can be tail-called
391  */
392 static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
393 					 char *args)
394 {
395 	pr_err("Free space limits must be in range 0%%<=stop<cull<run<100%%\n");
396 
397 	return -EINVAL;
398 }
399 
400 /*
401  * Set the percentage of files at which to stop culling
402  * - command: "frun <N>%"
403  */
404 static int cachefiles_daemon_frun(struct cachefiles_cache *cache, char *args)
405 {
406 	unsigned long frun;
407 
408 	_enter(",%s", args);
409 
410 	if (!*args)
411 		return -EINVAL;
412 
413 	frun = simple_strtoul(args, &args, 10);
414 	if (args[0] != '%' || args[1] != '\0')
415 		return -EINVAL;
416 
417 	if (frun <= cache->fcull_percent || frun >= 100)
418 		return cachefiles_daemon_range_error(cache, args);
419 
420 	cache->frun_percent = frun;
421 	return 0;
422 }
423 
424 /*
425  * Set the percentage of files at which to start culling
426  * - command: "fcull <N>%"
427  */
428 static int cachefiles_daemon_fcull(struct cachefiles_cache *cache, char *args)
429 {
430 	unsigned long fcull;
431 
432 	_enter(",%s", args);
433 
434 	if (!*args)
435 		return -EINVAL;
436 
437 	fcull = simple_strtoul(args, &args, 10);
438 	if (args[0] != '%' || args[1] != '\0')
439 		return -EINVAL;
440 
441 	if (fcull <= cache->fstop_percent || fcull >= cache->frun_percent)
442 		return cachefiles_daemon_range_error(cache, args);
443 
444 	cache->fcull_percent = fcull;
445 	return 0;
446 }
447 
448 /*
449  * Set the percentage of files at which to stop allocating
450  * - command: "fstop <N>%"
451  */
452 static int cachefiles_daemon_fstop(struct cachefiles_cache *cache, char *args)
453 {
454 	unsigned long fstop;
455 
456 	_enter(",%s", args);
457 
458 	if (!*args)
459 		return -EINVAL;
460 
461 	fstop = simple_strtoul(args, &args, 10);
462 	if (args[0] != '%' || args[1] != '\0')
463 		return -EINVAL;
464 
465 	if (fstop >= cache->fcull_percent)
466 		return cachefiles_daemon_range_error(cache, args);
467 
468 	cache->fstop_percent = fstop;
469 	return 0;
470 }
471 
472 /*
473  * Set the percentage of blocks at which to stop culling
474  * - command: "brun <N>%"
475  */
476 static int cachefiles_daemon_brun(struct cachefiles_cache *cache, char *args)
477 {
478 	unsigned long brun;
479 
480 	_enter(",%s", args);
481 
482 	if (!*args)
483 		return -EINVAL;
484 
485 	brun = simple_strtoul(args, &args, 10);
486 	if (args[0] != '%' || args[1] != '\0')
487 		return -EINVAL;
488 
489 	if (brun <= cache->bcull_percent || brun >= 100)
490 		return cachefiles_daemon_range_error(cache, args);
491 
492 	cache->brun_percent = brun;
493 	return 0;
494 }
495 
496 /*
497  * Set the percentage of blocks at which to start culling
498  * - command: "bcull <N>%"
499  */
500 static int cachefiles_daemon_bcull(struct cachefiles_cache *cache, char *args)
501 {
502 	unsigned long bcull;
503 
504 	_enter(",%s", args);
505 
506 	if (!*args)
507 		return -EINVAL;
508 
509 	bcull = simple_strtoul(args, &args, 10);
510 	if (args[0] != '%' || args[1] != '\0')
511 		return -EINVAL;
512 
513 	if (bcull <= cache->bstop_percent || bcull >= cache->brun_percent)
514 		return cachefiles_daemon_range_error(cache, args);
515 
516 	cache->bcull_percent = bcull;
517 	return 0;
518 }
519 
520 /*
521  * Set the percentage of blocks at which to stop allocating
522  * - command: "bstop <N>%"
523  */
524 static int cachefiles_daemon_bstop(struct cachefiles_cache *cache, char *args)
525 {
526 	unsigned long bstop;
527 
528 	_enter(",%s", args);
529 
530 	if (!*args)
531 		return -EINVAL;
532 
533 	bstop = simple_strtoul(args, &args, 10);
534 	if (args[0] != '%' || args[1] != '\0')
535 		return -EINVAL;
536 
537 	if (bstop >= cache->bcull_percent)
538 		return cachefiles_daemon_range_error(cache, args);
539 
540 	cache->bstop_percent = bstop;
541 	return 0;
542 }
543 
544 /*
545  * Set the cache directory
546  * - command: "dir <name>"
547  */
548 static int cachefiles_daemon_dir(struct cachefiles_cache *cache, char *args)
549 {
550 	char *dir;
551 
552 	_enter(",%s", args);
553 
554 	if (!*args) {
555 		pr_err("Empty directory specified\n");
556 		return -EINVAL;
557 	}
558 
559 	if (cache->rootdirname) {
560 		pr_err("Second cache directory specified\n");
561 		return -EEXIST;
562 	}
563 
564 	dir = kstrdup(args, GFP_KERNEL);
565 	if (!dir)
566 		return -ENOMEM;
567 
568 	cache->rootdirname = dir;
569 	return 0;
570 }
571 
572 /*
573  * Set the cache security context
574  * - command: "secctx <ctx>"
575  */
576 static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args)
577 {
578 	char *secctx;
579 
580 	_enter(",%s", args);
581 
582 	if (!*args) {
583 		pr_err("Empty security context specified\n");
584 		return -EINVAL;
585 	}
586 
587 	if (cache->secctx) {
588 		pr_err("Second security context specified\n");
589 		return -EINVAL;
590 	}
591 
592 	secctx = kstrdup(args, GFP_KERNEL);
593 	if (!secctx)
594 		return -ENOMEM;
595 
596 	cache->secctx = secctx;
597 	return 0;
598 }
599 
600 /*
601  * Set the cache tag
602  * - command: "tag <name>"
603  */
604 static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args)
605 {
606 	char *tag;
607 
608 	_enter(",%s", args);
609 
610 	if (!*args) {
611 		pr_err("Empty tag specified\n");
612 		return -EINVAL;
613 	}
614 
615 	if (cache->tag)
616 		return -EEXIST;
617 
618 	tag = kstrdup(args, GFP_KERNEL);
619 	if (!tag)
620 		return -ENOMEM;
621 
622 	cache->tag = tag;
623 	return 0;
624 }
625 
626 /*
627  * Request a node in the cache be culled from the current working directory
628  * - command: "cull <name>"
629  */
630 static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args)
631 {
632 	struct path path;
633 	const struct cred *saved_cred;
634 	int ret;
635 
636 	_enter(",%s", args);
637 
638 	if (strchr(args, '/'))
639 		goto inval;
640 
641 	if (!test_bit(CACHEFILES_READY, &cache->flags)) {
642 		pr_err("cull applied to unready cache\n");
643 		return -EIO;
644 	}
645 
646 	if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
647 		pr_err("cull applied to dead cache\n");
648 		return -EIO;
649 	}
650 
651 	get_fs_pwd(current->fs, &path);
652 
653 	if (!d_can_lookup(path.dentry))
654 		goto notdir;
655 
656 	cachefiles_begin_secure(cache, &saved_cred);
657 	ret = cachefiles_cull(cache, path.dentry, args);
658 	cachefiles_end_secure(cache, saved_cred);
659 
660 	path_put(&path);
661 	_leave(" = %d", ret);
662 	return ret;
663 
664 notdir:
665 	path_put(&path);
666 	pr_err("cull command requires dirfd to be a directory\n");
667 	return -ENOTDIR;
668 
669 inval:
670 	pr_err("cull command requires dirfd and filename\n");
671 	return -EINVAL;
672 }
673 
674 /*
675  * Set debugging mode
676  * - command: "debug <mask>"
677  */
678 static int cachefiles_daemon_debug(struct cachefiles_cache *cache, char *args)
679 {
680 	unsigned long mask;
681 
682 	_enter(",%s", args);
683 
684 	mask = simple_strtoul(args, &args, 0);
685 	if (args[0] != '\0')
686 		goto inval;
687 
688 	cachefiles_debug = mask;
689 	_leave(" = 0");
690 	return 0;
691 
692 inval:
693 	pr_err("debug command requires mask\n");
694 	return -EINVAL;
695 }
696 
697 /*
698  * Find out whether an object in the current working directory is in use or not
699  * - command: "inuse <name>"
700  */
701 static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
702 {
703 	struct path path;
704 	const struct cred *saved_cred;
705 	int ret;
706 
707 	//_enter(",%s", args);
708 
709 	if (strchr(args, '/'))
710 		goto inval;
711 
712 	if (!test_bit(CACHEFILES_READY, &cache->flags)) {
713 		pr_err("inuse applied to unready cache\n");
714 		return -EIO;
715 	}
716 
717 	if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
718 		pr_err("inuse applied to dead cache\n");
719 		return -EIO;
720 	}
721 
722 	get_fs_pwd(current->fs, &path);
723 
724 	if (!d_can_lookup(path.dentry))
725 		goto notdir;
726 
727 	cachefiles_begin_secure(cache, &saved_cred);
728 	ret = cachefiles_check_in_use(cache, path.dentry, args);
729 	cachefiles_end_secure(cache, saved_cred);
730 
731 	path_put(&path);
732 	//_leave(" = %d", ret);
733 	return ret;
734 
735 notdir:
736 	path_put(&path);
737 	pr_err("inuse command requires dirfd to be a directory\n");
738 	return -ENOTDIR;
739 
740 inval:
741 	pr_err("inuse command requires dirfd and filename\n");
742 	return -EINVAL;
743 }
744 
745 /*
746  * Bind a directory as a cache
747  */
748 static int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
749 {
750 	_enter("{%u,%u,%u,%u,%u,%u},%s",
751 	       cache->frun_percent,
752 	       cache->fcull_percent,
753 	       cache->fstop_percent,
754 	       cache->brun_percent,
755 	       cache->bcull_percent,
756 	       cache->bstop_percent,
757 	       args);
758 
759 	if (cache->fstop_percent >= cache->fcull_percent ||
760 	    cache->fcull_percent >= cache->frun_percent ||
761 	    cache->frun_percent  >= 100)
762 		return -ERANGE;
763 
764 	if (cache->bstop_percent >= cache->bcull_percent ||
765 	    cache->bcull_percent >= cache->brun_percent ||
766 	    cache->brun_percent  >= 100)
767 		return -ERANGE;
768 
769 	if (!cache->rootdirname) {
770 		pr_err("No cache directory specified\n");
771 		return -EINVAL;
772 	}
773 
774 	/* Don't permit already bound caches to be re-bound */
775 	if (test_bit(CACHEFILES_READY, &cache->flags)) {
776 		pr_err("Cache already bound\n");
777 		return -EBUSY;
778 	}
779 
780 	if (IS_ENABLED(CONFIG_CACHEFILES_ONDEMAND)) {
781 		if (!strcmp(args, "ondemand")) {
782 			set_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags);
783 		} else if (*args) {
784 			pr_err("Invalid argument to the 'bind' command\n");
785 			return -EINVAL;
786 		}
787 	} else if (*args) {
788 		pr_err("'bind' command doesn't take an argument\n");
789 		return -EINVAL;
790 	}
791 
792 	/* Make sure we have copies of the tag string */
793 	if (!cache->tag) {
794 		/*
795 		 * The tag string is released by the fops->release()
796 		 * function, so we don't release it on error here
797 		 */
798 		cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
799 		if (!cache->tag)
800 			return -ENOMEM;
801 	}
802 
803 	return cachefiles_add_cache(cache);
804 }
805 
806 /*
807  * Unbind a cache.
808  */
809 static void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
810 {
811 	_enter("");
812 
813 	if (test_bit(CACHEFILES_READY, &cache->flags))
814 		cachefiles_withdraw_cache(cache);
815 
816 	cachefiles_put_directory(cache->graveyard);
817 	cachefiles_put_directory(cache->store);
818 	mntput(cache->mnt);
819 	put_cred(cache->cache_cred);
820 
821 	kfree(cache->rootdirname);
822 	kfree(cache->secctx);
823 	kfree(cache->tag);
824 
825 	_leave("");
826 }
827