xref: /openbmc/linux/fs/cachefiles/daemon.c (revision abb84c46) 
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 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 		__xa_erase(xa, index);
163 	}
164 	xa_unlock(xa);
165 
166 	xa_destroy(&cache->reqs);
167 	xa_destroy(&cache->ondemand_ids);
168 }
169 
170 void cachefiles_put_unbind_pincount(struct cachefiles_cache *cache)
171 {
172 	if (refcount_dec_and_test(&cache->unbind_pincount)) {
173 		cachefiles_daemon_unbind(cache);
174 		cachefiles_open = 0;
175 		kfree(cache);
176 	}
177 }
178 
179 void cachefiles_get_unbind_pincount(struct cachefiles_cache *cache)
180 {
181 	refcount_inc(&cache->unbind_pincount);
182 }
183 
184 /*
185  * Release a cache.
186  */
187 static int cachefiles_daemon_release(struct inode *inode, struct file *file)
188 {
189 	struct cachefiles_cache *cache = file->private_data;
190 
191 	_enter("");
192 
193 	ASSERT(cache);
194 
195 	set_bit(CACHEFILES_DEAD, &cache->flags);
196 
197 	if (cachefiles_in_ondemand_mode(cache))
198 		cachefiles_flush_reqs(cache);
199 
200 	/* clean up the control file interface */
201 	cache->cachefilesd = NULL;
202 	file->private_data = NULL;
203 
204 	cachefiles_put_unbind_pincount(cache);
205 
206 	_leave("");
207 	return 0;
208 }
209 
210 static ssize_t cachefiles_do_daemon_read(struct cachefiles_cache *cache,
211 					 char __user *_buffer, size_t buflen)
212 {
213 	unsigned long long b_released;
214 	unsigned f_released;
215 	char buffer[256];
216 	int n;
217 
218 	/* check how much space the cache has */
219 	cachefiles_has_space(cache, 0, 0, cachefiles_has_space_check);
220 
221 	/* summarise */
222 	f_released = atomic_xchg(&cache->f_released, 0);
223 	b_released = atomic_long_xchg(&cache->b_released, 0);
224 	clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
225 
226 	n = snprintf(buffer, sizeof(buffer),
227 		     "cull=%c"
228 		     " frun=%llx"
229 		     " fcull=%llx"
230 		     " fstop=%llx"
231 		     " brun=%llx"
232 		     " bcull=%llx"
233 		     " bstop=%llx"
234 		     " freleased=%x"
235 		     " breleased=%llx",
236 		     test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
237 		     (unsigned long long) cache->frun,
238 		     (unsigned long long) cache->fcull,
239 		     (unsigned long long) cache->fstop,
240 		     (unsigned long long) cache->brun,
241 		     (unsigned long long) cache->bcull,
242 		     (unsigned long long) cache->bstop,
243 		     f_released,
244 		     b_released);
245 
246 	if (n > buflen)
247 		return -EMSGSIZE;
248 
249 	if (copy_to_user(_buffer, buffer, n) != 0)
250 		return -EFAULT;
251 
252 	return n;
253 }
254 
255 /*
256  * Read the cache state.
257  */
258 static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
259 				      size_t buflen, loff_t *pos)
260 {
261 	struct cachefiles_cache *cache = file->private_data;
262 
263 	//_enter(",,%zu,", buflen);
264 
265 	if (!test_bit(CACHEFILES_READY, &cache->flags))
266 		return 0;
267 
268 	if (cachefiles_in_ondemand_mode(cache))
269 		return cachefiles_ondemand_daemon_read(cache, _buffer, buflen);
270 	else
271 		return cachefiles_do_daemon_read(cache, _buffer, buflen);
272 }
273 
274 /*
275  * Take a command from cachefilesd, parse it and act on it.
276  */
277 static ssize_t cachefiles_daemon_write(struct file *file,
278 				       const char __user *_data,
279 				       size_t datalen,
280 				       loff_t *pos)
281 {
282 	const struct cachefiles_daemon_cmd *cmd;
283 	struct cachefiles_cache *cache = file->private_data;
284 	ssize_t ret;
285 	char *data, *args, *cp;
286 
287 	//_enter(",,%zu,", datalen);
288 
289 	ASSERT(cache);
290 
291 	if (test_bit(CACHEFILES_DEAD, &cache->flags))
292 		return -EIO;
293 
294 	if (datalen > PAGE_SIZE - 1)
295 		return -EOPNOTSUPP;
296 
297 	/* drag the command string into the kernel so we can parse it */
298 	data = memdup_user_nul(_data, datalen);
299 	if (IS_ERR(data))
300 		return PTR_ERR(data);
301 
302 	ret = -EINVAL;
303 	if (memchr(data, '\0', datalen))
304 		goto error;
305 
306 	/* strip any newline */
307 	cp = memchr(data, '\n', datalen);
308 	if (cp) {
309 		if (cp == data)
310 			goto error;
311 
312 		*cp = '\0';
313 	}
314 
315 	/* parse the command */
316 	ret = -EOPNOTSUPP;
317 
318 	for (args = data; *args; args++)
319 		if (isspace(*args))
320 			break;
321 	if (*args) {
322 		if (args == data)
323 			goto error;
324 		*args = '\0';
325 		args = skip_spaces(++args);
326 	}
327 
328 	/* run the appropriate command handler */
329 	for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
330 		if (strcmp(cmd->name, data) == 0)
331 			goto found_command;
332 
333 error:
334 	kfree(data);
335 	//_leave(" = %zd", ret);
336 	return ret;
337 
338 found_command:
339 	mutex_lock(&cache->daemon_mutex);
340 
341 	ret = -EIO;
342 	if (!test_bit(CACHEFILES_DEAD, &cache->flags))
343 		ret = cmd->handler(cache, args);
344 
345 	mutex_unlock(&cache->daemon_mutex);
346 
347 	if (ret == 0)
348 		ret = datalen;
349 	goto error;
350 }
351 
352 /*
353  * Poll for culling state
354  * - use EPOLLOUT to indicate culling state
355  */
356 static __poll_t cachefiles_daemon_poll(struct file *file,
357 					   struct poll_table_struct *poll)
358 {
359 	struct cachefiles_cache *cache = file->private_data;
360 	__poll_t mask;
361 
362 	poll_wait(file, &cache->daemon_pollwq, poll);
363 	mask = 0;
364 
365 	if (cachefiles_in_ondemand_mode(cache)) {
366 		if (!xa_empty(&cache->reqs))
367 			mask |= EPOLLIN;
368 	} else {
369 		if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
370 			mask |= EPOLLIN;
371 	}
372 
373 	if (test_bit(CACHEFILES_CULLING, &cache->flags))
374 		mask |= EPOLLOUT;
375 
376 	return mask;
377 }
378 
379 /*
380  * Give a range error for cache space constraints
381  * - can be tail-called
382  */
383 static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
384 					 char *args)
385 {
386 	pr_err("Free space limits must be in range 0%%<=stop<cull<run<100%%\n");
387 
388 	return -EINVAL;
389 }
390 
391 /*
392  * Set the percentage of files at which to stop culling
393  * - command: "frun <N>%"
394  */
395 static int cachefiles_daemon_frun(struct cachefiles_cache *cache, char *args)
396 {
397 	unsigned long frun;
398 
399 	_enter(",%s", args);
400 
401 	if (!*args)
402 		return -EINVAL;
403 
404 	frun = simple_strtoul(args, &args, 10);
405 	if (args[0] != '%' || args[1] != '\0')
406 		return -EINVAL;
407 
408 	if (frun <= cache->fcull_percent || frun >= 100)
409 		return cachefiles_daemon_range_error(cache, args);
410 
411 	cache->frun_percent = frun;
412 	return 0;
413 }
414 
415 /*
416  * Set the percentage of files at which to start culling
417  * - command: "fcull <N>%"
418  */
419 static int cachefiles_daemon_fcull(struct cachefiles_cache *cache, char *args)
420 {
421 	unsigned long fcull;
422 
423 	_enter(",%s", args);
424 
425 	if (!*args)
426 		return -EINVAL;
427 
428 	fcull = simple_strtoul(args, &args, 10);
429 	if (args[0] != '%' || args[1] != '\0')
430 		return -EINVAL;
431 
432 	if (fcull <= cache->fstop_percent || fcull >= cache->frun_percent)
433 		return cachefiles_daemon_range_error(cache, args);
434 
435 	cache->fcull_percent = fcull;
436 	return 0;
437 }
438 
439 /*
440  * Set the percentage of files at which to stop allocating
441  * - command: "fstop <N>%"
442  */
443 static int cachefiles_daemon_fstop(struct cachefiles_cache *cache, char *args)
444 {
445 	unsigned long fstop;
446 
447 	_enter(",%s", args);
448 
449 	if (!*args)
450 		return -EINVAL;
451 
452 	fstop = simple_strtoul(args, &args, 10);
453 	if (args[0] != '%' || args[1] != '\0')
454 		return -EINVAL;
455 
456 	if (fstop >= cache->fcull_percent)
457 		return cachefiles_daemon_range_error(cache, args);
458 
459 	cache->fstop_percent = fstop;
460 	return 0;
461 }
462 
463 /*
464  * Set the percentage of blocks at which to stop culling
465  * - command: "brun <N>%"
466  */
467 static int cachefiles_daemon_brun(struct cachefiles_cache *cache, char *args)
468 {
469 	unsigned long brun;
470 
471 	_enter(",%s", args);
472 
473 	if (!*args)
474 		return -EINVAL;
475 
476 	brun = simple_strtoul(args, &args, 10);
477 	if (args[0] != '%' || args[1] != '\0')
478 		return -EINVAL;
479 
480 	if (brun <= cache->bcull_percent || brun >= 100)
481 		return cachefiles_daemon_range_error(cache, args);
482 
483 	cache->brun_percent = brun;
484 	return 0;
485 }
486 
487 /*
488  * Set the percentage of blocks at which to start culling
489  * - command: "bcull <N>%"
490  */
491 static int cachefiles_daemon_bcull(struct cachefiles_cache *cache, char *args)
492 {
493 	unsigned long bcull;
494 
495 	_enter(",%s", args);
496 
497 	if (!*args)
498 		return -EINVAL;
499 
500 	bcull = simple_strtoul(args, &args, 10);
501 	if (args[0] != '%' || args[1] != '\0')
502 		return -EINVAL;
503 
504 	if (bcull <= cache->bstop_percent || bcull >= cache->brun_percent)
505 		return cachefiles_daemon_range_error(cache, args);
506 
507 	cache->bcull_percent = bcull;
508 	return 0;
509 }
510 
511 /*
512  * Set the percentage of blocks at which to stop allocating
513  * - command: "bstop <N>%"
514  */
515 static int cachefiles_daemon_bstop(struct cachefiles_cache *cache, char *args)
516 {
517 	unsigned long bstop;
518 
519 	_enter(",%s", args);
520 
521 	if (!*args)
522 		return -EINVAL;
523 
524 	bstop = simple_strtoul(args, &args, 10);
525 	if (args[0] != '%' || args[1] != '\0')
526 		return -EINVAL;
527 
528 	if (bstop >= cache->bcull_percent)
529 		return cachefiles_daemon_range_error(cache, args);
530 
531 	cache->bstop_percent = bstop;
532 	return 0;
533 }
534 
535 /*
536  * Set the cache directory
537  * - command: "dir <name>"
538  */
539 static int cachefiles_daemon_dir(struct cachefiles_cache *cache, char *args)
540 {
541 	char *dir;
542 
543 	_enter(",%s", args);
544 
545 	if (!*args) {
546 		pr_err("Empty directory specified\n");
547 		return -EINVAL;
548 	}
549 
550 	if (cache->rootdirname) {
551 		pr_err("Second cache directory specified\n");
552 		return -EEXIST;
553 	}
554 
555 	dir = kstrdup(args, GFP_KERNEL);
556 	if (!dir)
557 		return -ENOMEM;
558 
559 	cache->rootdirname = dir;
560 	return 0;
561 }
562 
563 /*
564  * Set the cache security context
565  * - command: "secctx <ctx>"
566  */
567 static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args)
568 {
569 	char *secctx;
570 
571 	_enter(",%s", args);
572 
573 	if (!*args) {
574 		pr_err("Empty security context specified\n");
575 		return -EINVAL;
576 	}
577 
578 	if (cache->secctx) {
579 		pr_err("Second security context specified\n");
580 		return -EINVAL;
581 	}
582 
583 	secctx = kstrdup(args, GFP_KERNEL);
584 	if (!secctx)
585 		return -ENOMEM;
586 
587 	cache->secctx = secctx;
588 	return 0;
589 }
590 
591 /*
592  * Set the cache tag
593  * - command: "tag <name>"
594  */
595 static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args)
596 {
597 	char *tag;
598 
599 	_enter(",%s", args);
600 
601 	if (!*args) {
602 		pr_err("Empty tag specified\n");
603 		return -EINVAL;
604 	}
605 
606 	if (cache->tag)
607 		return -EEXIST;
608 
609 	tag = kstrdup(args, GFP_KERNEL);
610 	if (!tag)
611 		return -ENOMEM;
612 
613 	cache->tag = tag;
614 	return 0;
615 }
616 
617 /*
618  * Request a node in the cache be culled from the current working directory
619  * - command: "cull <name>"
620  */
621 static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args)
622 {
623 	struct path path;
624 	const struct cred *saved_cred;
625 	int ret;
626 
627 	_enter(",%s", args);
628 
629 	if (strchr(args, '/'))
630 		goto inval;
631 
632 	if (!test_bit(CACHEFILES_READY, &cache->flags)) {
633 		pr_err("cull applied to unready cache\n");
634 		return -EIO;
635 	}
636 
637 	if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
638 		pr_err("cull applied to dead cache\n");
639 		return -EIO;
640 	}
641 
642 	get_fs_pwd(current->fs, &path);
643 
644 	if (!d_can_lookup(path.dentry))
645 		goto notdir;
646 
647 	cachefiles_begin_secure(cache, &saved_cred);
648 	ret = cachefiles_cull(cache, path.dentry, args);
649 	cachefiles_end_secure(cache, saved_cred);
650 
651 	path_put(&path);
652 	_leave(" = %d", ret);
653 	return ret;
654 
655 notdir:
656 	path_put(&path);
657 	pr_err("cull command requires dirfd to be a directory\n");
658 	return -ENOTDIR;
659 
660 inval:
661 	pr_err("cull command requires dirfd and filename\n");
662 	return -EINVAL;
663 }
664 
665 /*
666  * Set debugging mode
667  * - command: "debug <mask>"
668  */
669 static int cachefiles_daemon_debug(struct cachefiles_cache *cache, char *args)
670 {
671 	unsigned long mask;
672 
673 	_enter(",%s", args);
674 
675 	mask = simple_strtoul(args, &args, 0);
676 	if (args[0] != '\0')
677 		goto inval;
678 
679 	cachefiles_debug = mask;
680 	_leave(" = 0");
681 	return 0;
682 
683 inval:
684 	pr_err("debug command requires mask\n");
685 	return -EINVAL;
686 }
687 
688 /*
689  * Find out whether an object in the current working directory is in use or not
690  * - command: "inuse <name>"
691  */
692 static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
693 {
694 	struct path path;
695 	const struct cred *saved_cred;
696 	int ret;
697 
698 	//_enter(",%s", args);
699 
700 	if (strchr(args, '/'))
701 		goto inval;
702 
703 	if (!test_bit(CACHEFILES_READY, &cache->flags)) {
704 		pr_err("inuse applied to unready cache\n");
705 		return -EIO;
706 	}
707 
708 	if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
709 		pr_err("inuse applied to dead cache\n");
710 		return -EIO;
711 	}
712 
713 	get_fs_pwd(current->fs, &path);
714 
715 	if (!d_can_lookup(path.dentry))
716 		goto notdir;
717 
718 	cachefiles_begin_secure(cache, &saved_cred);
719 	ret = cachefiles_check_in_use(cache, path.dentry, args);
720 	cachefiles_end_secure(cache, saved_cred);
721 
722 	path_put(&path);
723 	//_leave(" = %d", ret);
724 	return ret;
725 
726 notdir:
727 	path_put(&path);
728 	pr_err("inuse command requires dirfd to be a directory\n");
729 	return -ENOTDIR;
730 
731 inval:
732 	pr_err("inuse command requires dirfd and filename\n");
733 	return -EINVAL;
734 }
735 
736 /*
737  * Bind a directory as a cache
738  */
739 static int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
740 {
741 	_enter("{%u,%u,%u,%u,%u,%u},%s",
742 	       cache->frun_percent,
743 	       cache->fcull_percent,
744 	       cache->fstop_percent,
745 	       cache->brun_percent,
746 	       cache->bcull_percent,
747 	       cache->bstop_percent,
748 	       args);
749 
750 	if (cache->fstop_percent >= cache->fcull_percent ||
751 	    cache->fcull_percent >= cache->frun_percent ||
752 	    cache->frun_percent  >= 100)
753 		return -ERANGE;
754 
755 	if (cache->bstop_percent >= cache->bcull_percent ||
756 	    cache->bcull_percent >= cache->brun_percent ||
757 	    cache->brun_percent  >= 100)
758 		return -ERANGE;
759 
760 	if (!cache->rootdirname) {
761 		pr_err("No cache directory specified\n");
762 		return -EINVAL;
763 	}
764 
765 	/* Don't permit already bound caches to be re-bound */
766 	if (test_bit(CACHEFILES_READY, &cache->flags)) {
767 		pr_err("Cache already bound\n");
768 		return -EBUSY;
769 	}
770 
771 	if (IS_ENABLED(CONFIG_CACHEFILES_ONDEMAND)) {
772 		if (!strcmp(args, "ondemand")) {
773 			set_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags);
774 		} else if (*args) {
775 			pr_err("Invalid argument to the 'bind' command\n");
776 			return -EINVAL;
777 		}
778 	} else if (*args) {
779 		pr_err("'bind' command doesn't take an argument\n");
780 		return -EINVAL;
781 	}
782 
783 	/* Make sure we have copies of the tag string */
784 	if (!cache->tag) {
785 		/*
786 		 * The tag string is released by the fops->release()
787 		 * function, so we don't release it on error here
788 		 */
789 		cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
790 		if (!cache->tag)
791 			return -ENOMEM;
792 	}
793 
794 	return cachefiles_add_cache(cache);
795 }
796 
797 /*
798  * Unbind a cache.
799  */
800 static void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
801 {
802 	_enter("");
803 
804 	if (test_bit(CACHEFILES_READY, &cache->flags))
805 		cachefiles_withdraw_cache(cache);
806 
807 	cachefiles_put_directory(cache->graveyard);
808 	cachefiles_put_directory(cache->store);
809 	mntput(cache->mnt);
810 	put_cred(cache->cache_cred);
811 
812 	kfree(cache->rootdirname);
813 	kfree(cache->secctx);
814 	kfree(cache->tag);
815 
816 	_leave("");
817 }
818