1 // SPDX-License-Identifier: GPL-2.0-or-later
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
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>
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>
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,
28 static ssize_t cachefiles_daemon_write(struct file *, const char __user *,
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 *);
45 static unsigned long cachefiles_open;
47 const struct file_operations cachefiles_daemon_fops = {
49 .open = cachefiles_daemon_open,
50 .release = cachefiles_daemon_release,
51 .read = cachefiles_daemon_read,
52 .write = cachefiles_daemon_write,
53 .poll = cachefiles_daemon_poll,
54 .llseek = noop_llseek,
57 struct cachefiles_daemon_cmd {
59 int (*handler)(struct cachefiles_cache *cache, char *args);
62 static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = {
63 { "bind", cachefiles_daemon_bind },
64 { "brun", cachefiles_daemon_brun },
65 { "bcull", cachefiles_daemon_bcull },
66 { "bstop", cachefiles_daemon_bstop },
67 { "cull", cachefiles_daemon_cull },
68 { "debug", cachefiles_daemon_debug },
69 { "dir", cachefiles_daemon_dir },
70 { "frun", cachefiles_daemon_frun },
71 { "fcull", cachefiles_daemon_fcull },
72 { "fstop", cachefiles_daemon_fstop },
73 { "inuse", cachefiles_daemon_inuse },
74 { "secctx", cachefiles_daemon_secctx },
75 { "tag", cachefiles_daemon_tag },
83 static int cachefiles_daemon_open(struct inode *inode, struct file *file)
85 struct cachefiles_cache *cache;
89 /* only the superuser may do this */
90 if (!capable(CAP_SYS_ADMIN))
93 /* the cachefiles device may only be open once at a time */
94 if (xchg(&cachefiles_open, 1) == 1)
97 /* allocate a cache record */
98 cache = kzalloc(sizeof(struct cachefiles_cache), GFP_KERNEL);
104 mutex_init(&cache->daemon_mutex);
105 cache->active_nodes = RB_ROOT;
106 rwlock_init(&cache->active_lock);
107 init_waitqueue_head(&cache->daemon_pollwq);
109 /* set default caching limits
110 * - limit at 1% free space and/or free files
111 * - cull below 5% free space and/or free files
112 * - cease culling above 7% free space and/or free files
114 cache->frun_percent = 7;
115 cache->fcull_percent = 5;
116 cache->fstop_percent = 1;
117 cache->brun_percent = 7;
118 cache->bcull_percent = 5;
119 cache->bstop_percent = 1;
121 file->private_data = cache;
122 cache->cachefilesd = file;
129 static int cachefiles_daemon_release(struct inode *inode, struct file *file)
131 struct cachefiles_cache *cache = file->private_data;
137 set_bit(CACHEFILES_DEAD, &cache->flags);
139 cachefiles_daemon_unbind(cache);
141 ASSERT(!cache->active_nodes.rb_node);
143 /* clean up the control file interface */
144 cache->cachefilesd = NULL;
145 file->private_data = NULL;
155 * read the cache state
157 static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
158 size_t buflen, loff_t *pos)
160 struct cachefiles_cache *cache = file->private_data;
161 unsigned long long b_released;
166 //_enter(",,%zu,", buflen);
168 if (!test_bit(CACHEFILES_READY, &cache->flags))
171 /* check how much space the cache has */
172 cachefiles_has_space(cache, 0, 0);
175 f_released = atomic_xchg(&cache->f_released, 0);
176 b_released = atomic_long_xchg(&cache->b_released, 0);
177 clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
179 n = snprintf(buffer, sizeof(buffer),
189 test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
190 (unsigned long long) cache->frun,
191 (unsigned long long) cache->fcull,
192 (unsigned long long) cache->fstop,
193 (unsigned long long) cache->brun,
194 (unsigned long long) cache->bcull,
195 (unsigned long long) cache->bstop,
202 if (copy_to_user(_buffer, buffer, n) != 0)
211 static ssize_t cachefiles_daemon_write(struct file *file,
212 const char __user *_data,
216 const struct cachefiles_daemon_cmd *cmd;
217 struct cachefiles_cache *cache = file->private_data;
219 char *data, *args, *cp;
221 //_enter(",,%zu,", datalen);
225 if (test_bit(CACHEFILES_DEAD, &cache->flags))
228 if (datalen < 0 || datalen > PAGE_SIZE - 1)
231 /* drag the command string into the kernel so we can parse it */
232 data = memdup_user_nul(_data, datalen);
234 return PTR_ERR(data);
237 if (memchr(data, '\0', datalen))
240 /* strip any newline */
241 cp = memchr(data, '\n', datalen);
249 /* parse the command */
252 for (args = data; *args; args++)
259 args = skip_spaces(++args);
262 /* run the appropriate command handler */
263 for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
264 if (strcmp(cmd->name, data) == 0)
269 //_leave(" = %zd", ret);
273 mutex_lock(&cache->daemon_mutex);
276 if (!test_bit(CACHEFILES_DEAD, &cache->flags))
277 ret = cmd->handler(cache, args);
279 mutex_unlock(&cache->daemon_mutex);
287 * poll for culling state
288 * - use EPOLLOUT to indicate culling state
290 static __poll_t cachefiles_daemon_poll(struct file *file,
291 struct poll_table_struct *poll)
293 struct cachefiles_cache *cache = file->private_data;
296 poll_wait(file, &cache->daemon_pollwq, poll);
299 if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
302 if (test_bit(CACHEFILES_CULLING, &cache->flags))
309 * give a range error for cache space constraints
310 * - can be tail-called
312 static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
315 pr_err("Free space limits must be in range 0%%<=stop<cull<run<100%%\n");
321 * set the percentage of files at which to stop culling
322 * - command: "frun <N>%"
324 static int cachefiles_daemon_frun(struct cachefiles_cache *cache, char *args)
333 frun = simple_strtoul(args, &args, 10);
334 if (args[0] != '%' || args[1] != '\0')
337 if (frun <= cache->fcull_percent || frun >= 100)
338 return cachefiles_daemon_range_error(cache, args);
340 cache->frun_percent = frun;
345 * set the percentage of files at which to start culling
346 * - command: "fcull <N>%"
348 static int cachefiles_daemon_fcull(struct cachefiles_cache *cache, char *args)
357 fcull = simple_strtoul(args, &args, 10);
358 if (args[0] != '%' || args[1] != '\0')
361 if (fcull <= cache->fstop_percent || fcull >= cache->frun_percent)
362 return cachefiles_daemon_range_error(cache, args);
364 cache->fcull_percent = fcull;
369 * set the percentage of files at which to stop allocating
370 * - command: "fstop <N>%"
372 static int cachefiles_daemon_fstop(struct cachefiles_cache *cache, char *args)
381 fstop = simple_strtoul(args, &args, 10);
382 if (args[0] != '%' || args[1] != '\0')
385 if (fstop < 0 || fstop >= cache->fcull_percent)
386 return cachefiles_daemon_range_error(cache, args);
388 cache->fstop_percent = fstop;
393 * set the percentage of blocks at which to stop culling
394 * - command: "brun <N>%"
396 static int cachefiles_daemon_brun(struct cachefiles_cache *cache, char *args)
405 brun = simple_strtoul(args, &args, 10);
406 if (args[0] != '%' || args[1] != '\0')
409 if (brun <= cache->bcull_percent || brun >= 100)
410 return cachefiles_daemon_range_error(cache, args);
412 cache->brun_percent = brun;
417 * set the percentage of blocks at which to start culling
418 * - command: "bcull <N>%"
420 static int cachefiles_daemon_bcull(struct cachefiles_cache *cache, char *args)
429 bcull = simple_strtoul(args, &args, 10);
430 if (args[0] != '%' || args[1] != '\0')
433 if (bcull <= cache->bstop_percent || bcull >= cache->brun_percent)
434 return cachefiles_daemon_range_error(cache, args);
436 cache->bcull_percent = bcull;
441 * set the percentage of blocks at which to stop allocating
442 * - command: "bstop <N>%"
444 static int cachefiles_daemon_bstop(struct cachefiles_cache *cache, char *args)
453 bstop = simple_strtoul(args, &args, 10);
454 if (args[0] != '%' || args[1] != '\0')
457 if (bstop < 0 || bstop >= cache->bcull_percent)
458 return cachefiles_daemon_range_error(cache, args);
460 cache->bstop_percent = bstop;
465 * set the cache directory
466 * - command: "dir <name>"
468 static int cachefiles_daemon_dir(struct cachefiles_cache *cache, char *args)
475 pr_err("Empty directory specified\n");
479 if (cache->rootdirname) {
480 pr_err("Second cache directory specified\n");
484 dir = kstrdup(args, GFP_KERNEL);
488 cache->rootdirname = dir;
493 * set the cache security context
494 * - command: "secctx <ctx>"
496 static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args)
503 pr_err("Empty security context specified\n");
508 pr_err("Second security context specified\n");
512 secctx = kstrdup(args, GFP_KERNEL);
516 cache->secctx = secctx;
522 * - command: "tag <name>"
524 static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args)
531 pr_err("Empty tag specified\n");
538 tag = kstrdup(args, GFP_KERNEL);
547 * request a node in the cache be culled from the current working directory
548 * - command: "cull <name>"
550 static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args)
553 const struct cred *saved_cred;
558 if (strchr(args, '/'))
561 if (!test_bit(CACHEFILES_READY, &cache->flags)) {
562 pr_err("cull applied to unready cache\n");
566 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
567 pr_err("cull applied to dead cache\n");
571 /* extract the directory dentry from the cwd */
572 get_fs_pwd(current->fs, &path);
574 if (!d_can_lookup(path.dentry))
577 cachefiles_begin_secure(cache, &saved_cred);
578 ret = cachefiles_cull(cache, path.dentry, args);
579 cachefiles_end_secure(cache, saved_cred);
582 _leave(" = %d", ret);
587 pr_err("cull command requires dirfd to be a directory\n");
591 pr_err("cull command requires dirfd and filename\n");
597 * - command: "debug <mask>"
599 static int cachefiles_daemon_debug(struct cachefiles_cache *cache, char *args)
605 mask = simple_strtoul(args, &args, 0);
609 cachefiles_debug = mask;
614 pr_err("debug command requires mask\n");
619 * find out whether an object in the current working directory is in use or not
620 * - command: "inuse <name>"
622 static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
625 const struct cred *saved_cred;
628 //_enter(",%s", args);
630 if (strchr(args, '/'))
633 if (!test_bit(CACHEFILES_READY, &cache->flags)) {
634 pr_err("inuse applied to unready cache\n");
638 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
639 pr_err("inuse applied to dead cache\n");
643 /* extract the directory dentry from the cwd */
644 get_fs_pwd(current->fs, &path);
646 if (!d_can_lookup(path.dentry))
649 cachefiles_begin_secure(cache, &saved_cred);
650 ret = cachefiles_check_in_use(cache, path.dentry, args);
651 cachefiles_end_secure(cache, saved_cred);
654 //_leave(" = %d", ret);
659 pr_err("inuse command requires dirfd to be a directory\n");
663 pr_err("inuse command requires dirfd and filename\n");
668 * see if we have space for a number of pages and/or a number of files in the
671 int cachefiles_has_space(struct cachefiles_cache *cache,
672 unsigned fnr, unsigned bnr)
674 struct kstatfs stats;
677 .dentry = cache->mnt->mnt_root,
681 //_enter("{%llu,%llu,%llu,%llu,%llu,%llu},%u,%u",
682 // (unsigned long long) cache->frun,
683 // (unsigned long long) cache->fcull,
684 // (unsigned long long) cache->fstop,
685 // (unsigned long long) cache->brun,
686 // (unsigned long long) cache->bcull,
687 // (unsigned long long) cache->bstop,
690 /* find out how many pages of blockdev are available */
691 memset(&stats, 0, sizeof(stats));
693 ret = vfs_statfs(&path, &stats);
696 cachefiles_io_error(cache, "statfs failed");
697 _leave(" = %d", ret);
701 stats.f_bavail >>= cache->bshift;
703 //_debug("avail %llu,%llu",
704 // (unsigned long long) stats.f_ffree,
705 // (unsigned long long) stats.f_bavail);
707 /* see if there is sufficient space */
708 if (stats.f_ffree > fnr)
709 stats.f_ffree -= fnr;
713 if (stats.f_bavail > bnr)
714 stats.f_bavail -= bnr;
719 if (stats.f_ffree < cache->fstop ||
720 stats.f_bavail < cache->bstop)
724 if (stats.f_ffree < cache->fcull ||
725 stats.f_bavail < cache->bcull)
728 if (test_bit(CACHEFILES_CULLING, &cache->flags) &&
729 stats.f_ffree >= cache->frun &&
730 stats.f_bavail >= cache->brun &&
731 test_and_clear_bit(CACHEFILES_CULLING, &cache->flags)
733 _debug("cease culling");
734 cachefiles_state_changed(cache);
741 if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) {
742 _debug("### CULL CACHE ###");
743 cachefiles_state_changed(cache);
746 _leave(" = %d", ret);