blob: c2413561ea753f4ede277ec6736c49db738456f5 [file] [log] [blame]
David Howells9ae326a2009-04-03 16:42:41 +01001/* Daemon interface
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12#include <linux/module.h>
13#include <linux/init.h>
14#include <linux/sched.h>
15#include <linux/completion.h>
16#include <linux/slab.h>
17#include <linux/fs.h>
18#include <linux/file.h>
19#include <linux/namei.h>
20#include <linux/poll.h>
21#include <linux/mount.h>
22#include <linux/statfs.h>
23#include <linux/ctype.h>
André Goddard Rosae7d28602009-12-14 18:01:06 -080024#include <linux/string.h>
David Howells9ae326a2009-04-03 16:42:41 +010025#include <linux/fs_struct.h>
26#include "internal.h"
27
28static int cachefiles_daemon_open(struct inode *, struct file *);
29static int cachefiles_daemon_release(struct inode *, struct file *);
30static ssize_t cachefiles_daemon_read(struct file *, char __user *, size_t,
31 loff_t *);
32static ssize_t cachefiles_daemon_write(struct file *, const char __user *,
33 size_t, loff_t *);
34static unsigned int cachefiles_daemon_poll(struct file *,
35 struct poll_table_struct *);
36static int cachefiles_daemon_frun(struct cachefiles_cache *, char *);
37static int cachefiles_daemon_fcull(struct cachefiles_cache *, char *);
38static int cachefiles_daemon_fstop(struct cachefiles_cache *, char *);
39static int cachefiles_daemon_brun(struct cachefiles_cache *, char *);
40static int cachefiles_daemon_bcull(struct cachefiles_cache *, char *);
41static int cachefiles_daemon_bstop(struct cachefiles_cache *, char *);
42static int cachefiles_daemon_cull(struct cachefiles_cache *, char *);
43static int cachefiles_daemon_debug(struct cachefiles_cache *, char *);
44static int cachefiles_daemon_dir(struct cachefiles_cache *, char *);
45static int cachefiles_daemon_inuse(struct cachefiles_cache *, char *);
46static int cachefiles_daemon_secctx(struct cachefiles_cache *, char *);
47static int cachefiles_daemon_tag(struct cachefiles_cache *, char *);
48
49static unsigned long cachefiles_open;
50
51const struct file_operations cachefiles_daemon_fops = {
52 .owner = THIS_MODULE,
53 .open = cachefiles_daemon_open,
54 .release = cachefiles_daemon_release,
55 .read = cachefiles_daemon_read,
56 .write = cachefiles_daemon_write,
57 .poll = cachefiles_daemon_poll,
58};
59
60struct cachefiles_daemon_cmd {
61 char name[8];
62 int (*handler)(struct cachefiles_cache *cache, char *args);
63};
64
65static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = {
66 { "bind", cachefiles_daemon_bind },
67 { "brun", cachefiles_daemon_brun },
68 { "bcull", cachefiles_daemon_bcull },
69 { "bstop", cachefiles_daemon_bstop },
70 { "cull", cachefiles_daemon_cull },
71 { "debug", cachefiles_daemon_debug },
72 { "dir", cachefiles_daemon_dir },
73 { "frun", cachefiles_daemon_frun },
74 { "fcull", cachefiles_daemon_fcull },
75 { "fstop", cachefiles_daemon_fstop },
76 { "inuse", cachefiles_daemon_inuse },
77 { "secctx", cachefiles_daemon_secctx },
78 { "tag", cachefiles_daemon_tag },
79 { "", NULL }
80};
81
82
83/*
84 * do various checks
85 */
86static int cachefiles_daemon_open(struct inode *inode, struct file *file)
87{
88 struct cachefiles_cache *cache;
89
90 _enter("");
91
92 /* only the superuser may do this */
93 if (!capable(CAP_SYS_ADMIN))
94 return -EPERM;
95
96 /* the cachefiles device may only be open once at a time */
97 if (xchg(&cachefiles_open, 1) == 1)
98 return -EBUSY;
99
100 /* allocate a cache record */
101 cache = kzalloc(sizeof(struct cachefiles_cache), GFP_KERNEL);
102 if (!cache) {
103 cachefiles_open = 0;
104 return -ENOMEM;
105 }
106
107 mutex_init(&cache->daemon_mutex);
108 cache->active_nodes = RB_ROOT;
109 rwlock_init(&cache->active_lock);
110 init_waitqueue_head(&cache->daemon_pollwq);
111
112 /* set default caching limits
113 * - limit at 1% free space and/or free files
114 * - cull below 5% free space and/or free files
115 * - cease culling above 7% free space and/or free files
116 */
117 cache->frun_percent = 7;
118 cache->fcull_percent = 5;
119 cache->fstop_percent = 1;
120 cache->brun_percent = 7;
121 cache->bcull_percent = 5;
122 cache->bstop_percent = 1;
123
124 file->private_data = cache;
125 cache->cachefilesd = file;
126 return 0;
127}
128
129/*
130 * release a cache
131 */
132static int cachefiles_daemon_release(struct inode *inode, struct file *file)
133{
134 struct cachefiles_cache *cache = file->private_data;
135
136 _enter("");
137
138 ASSERT(cache);
139
140 set_bit(CACHEFILES_DEAD, &cache->flags);
141
142 cachefiles_daemon_unbind(cache);
143
144 ASSERT(!cache->active_nodes.rb_node);
145
146 /* clean up the control file interface */
147 cache->cachefilesd = NULL;
148 file->private_data = NULL;
149 cachefiles_open = 0;
150
151 kfree(cache);
152
153 _leave("");
154 return 0;
155}
156
157/*
158 * read the cache state
159 */
160static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
161 size_t buflen, loff_t *pos)
162{
163 struct cachefiles_cache *cache = file->private_data;
164 char buffer[256];
165 int n;
166
167 //_enter(",,%zu,", buflen);
168
169 if (!test_bit(CACHEFILES_READY, &cache->flags))
170 return 0;
171
172 /* check how much space the cache has */
173 cachefiles_has_space(cache, 0, 0);
174
175 /* summarise */
176 clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
177
178 n = snprintf(buffer, sizeof(buffer),
179 "cull=%c"
180 " frun=%llx"
181 " fcull=%llx"
182 " fstop=%llx"
183 " brun=%llx"
184 " bcull=%llx"
185 " bstop=%llx",
186 test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
187 (unsigned long long) cache->frun,
188 (unsigned long long) cache->fcull,
189 (unsigned long long) cache->fstop,
190 (unsigned long long) cache->brun,
191 (unsigned long long) cache->bcull,
192 (unsigned long long) cache->bstop
193 );
194
195 if (n > buflen)
196 return -EMSGSIZE;
197
198 if (copy_to_user(_buffer, buffer, n) != 0)
199 return -EFAULT;
200
201 return n;
202}
203
204/*
205 * command the cache
206 */
207static ssize_t cachefiles_daemon_write(struct file *file,
208 const char __user *_data,
209 size_t datalen,
210 loff_t *pos)
211{
212 const struct cachefiles_daemon_cmd *cmd;
213 struct cachefiles_cache *cache = file->private_data;
214 ssize_t ret;
215 char *data, *args, *cp;
216
217 //_enter(",,%zu,", datalen);
218
219 ASSERT(cache);
220
221 if (test_bit(CACHEFILES_DEAD, &cache->flags))
222 return -EIO;
223
224 if (datalen < 0 || datalen > PAGE_SIZE - 1)
225 return -EOPNOTSUPP;
226
227 /* drag the command string into the kernel so we can parse it */
228 data = kmalloc(datalen + 1, GFP_KERNEL);
229 if (!data)
230 return -ENOMEM;
231
232 ret = -EFAULT;
233 if (copy_from_user(data, _data, datalen) != 0)
234 goto error;
235
236 data[datalen] = '\0';
237
238 ret = -EINVAL;
239 if (memchr(data, '\0', datalen))
240 goto error;
241
242 /* strip any newline */
243 cp = memchr(data, '\n', datalen);
244 if (cp) {
245 if (cp == data)
246 goto error;
247
248 *cp = '\0';
249 }
250
251 /* parse the command */
252 ret = -EOPNOTSUPP;
253
254 for (args = data; *args; args++)
255 if (isspace(*args))
256 break;
257 if (*args) {
258 if (args == data)
259 goto error;
260 *args = '\0';
André Goddard Rosae7d28602009-12-14 18:01:06 -0800261 args = skip_spaces(++args);
David Howells9ae326a2009-04-03 16:42:41 +0100262 }
263
264 /* run the appropriate command handler */
265 for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
266 if (strcmp(cmd->name, data) == 0)
267 goto found_command;
268
269error:
270 kfree(data);
271 //_leave(" = %zd", ret);
272 return ret;
273
274found_command:
275 mutex_lock(&cache->daemon_mutex);
276
277 ret = -EIO;
278 if (!test_bit(CACHEFILES_DEAD, &cache->flags))
279 ret = cmd->handler(cache, args);
280
281 mutex_unlock(&cache->daemon_mutex);
282
283 if (ret == 0)
284 ret = datalen;
285 goto error;
286}
287
288/*
289 * poll for culling state
290 * - use POLLOUT to indicate culling state
291 */
292static unsigned int cachefiles_daemon_poll(struct file *file,
293 struct poll_table_struct *poll)
294{
295 struct cachefiles_cache *cache = file->private_data;
296 unsigned int mask;
297
298 poll_wait(file, &cache->daemon_pollwq, poll);
299 mask = 0;
300
301 if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
302 mask |= POLLIN;
303
304 if (test_bit(CACHEFILES_CULLING, &cache->flags))
305 mask |= POLLOUT;
306
307 return mask;
308}
309
310/*
311 * give a range error for cache space constraints
312 * - can be tail-called
313 */
314static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
315 char *args)
316{
317 kerror("Free space limits must be in range"
318 " 0%%<=stop<cull<run<100%%");
319
320 return -EINVAL;
321}
322
323/*
324 * set the percentage of files at which to stop culling
325 * - command: "frun <N>%"
326 */
327static int cachefiles_daemon_frun(struct cachefiles_cache *cache, char *args)
328{
329 unsigned long frun;
330
331 _enter(",%s", args);
332
333 if (!*args)
334 return -EINVAL;
335
336 frun = simple_strtoul(args, &args, 10);
337 if (args[0] != '%' || args[1] != '\0')
338 return -EINVAL;
339
340 if (frun <= cache->fcull_percent || frun >= 100)
341 return cachefiles_daemon_range_error(cache, args);
342
343 cache->frun_percent = frun;
344 return 0;
345}
346
347/*
348 * set the percentage of files at which to start culling
349 * - command: "fcull <N>%"
350 */
351static int cachefiles_daemon_fcull(struct cachefiles_cache *cache, char *args)
352{
353 unsigned long fcull;
354
355 _enter(",%s", args);
356
357 if (!*args)
358 return -EINVAL;
359
360 fcull = simple_strtoul(args, &args, 10);
361 if (args[0] != '%' || args[1] != '\0')
362 return -EINVAL;
363
364 if (fcull <= cache->fstop_percent || fcull >= cache->frun_percent)
365 return cachefiles_daemon_range_error(cache, args);
366
367 cache->fcull_percent = fcull;
368 return 0;
369}
370
371/*
372 * set the percentage of files at which to stop allocating
373 * - command: "fstop <N>%"
374 */
375static int cachefiles_daemon_fstop(struct cachefiles_cache *cache, char *args)
376{
377 unsigned long fstop;
378
379 _enter(",%s", args);
380
381 if (!*args)
382 return -EINVAL;
383
384 fstop = simple_strtoul(args, &args, 10);
385 if (args[0] != '%' || args[1] != '\0')
386 return -EINVAL;
387
388 if (fstop < 0 || fstop >= cache->fcull_percent)
389 return cachefiles_daemon_range_error(cache, args);
390
391 cache->fstop_percent = fstop;
392 return 0;
393}
394
395/*
396 * set the percentage of blocks at which to stop culling
397 * - command: "brun <N>%"
398 */
399static int cachefiles_daemon_brun(struct cachefiles_cache *cache, char *args)
400{
401 unsigned long brun;
402
403 _enter(",%s", args);
404
405 if (!*args)
406 return -EINVAL;
407
408 brun = simple_strtoul(args, &args, 10);
409 if (args[0] != '%' || args[1] != '\0')
410 return -EINVAL;
411
412 if (brun <= cache->bcull_percent || brun >= 100)
413 return cachefiles_daemon_range_error(cache, args);
414
415 cache->brun_percent = brun;
416 return 0;
417}
418
419/*
420 * set the percentage of blocks at which to start culling
421 * - command: "bcull <N>%"
422 */
423static int cachefiles_daemon_bcull(struct cachefiles_cache *cache, char *args)
424{
425 unsigned long bcull;
426
427 _enter(",%s", args);
428
429 if (!*args)
430 return -EINVAL;
431
432 bcull = simple_strtoul(args, &args, 10);
433 if (args[0] != '%' || args[1] != '\0')
434 return -EINVAL;
435
436 if (bcull <= cache->bstop_percent || bcull >= cache->brun_percent)
437 return cachefiles_daemon_range_error(cache, args);
438
439 cache->bcull_percent = bcull;
440 return 0;
441}
442
443/*
444 * set the percentage of blocks at which to stop allocating
445 * - command: "bstop <N>%"
446 */
447static int cachefiles_daemon_bstop(struct cachefiles_cache *cache, char *args)
448{
449 unsigned long bstop;
450
451 _enter(",%s", args);
452
453 if (!*args)
454 return -EINVAL;
455
456 bstop = simple_strtoul(args, &args, 10);
457 if (args[0] != '%' || args[1] != '\0')
458 return -EINVAL;
459
460 if (bstop < 0 || bstop >= cache->bcull_percent)
461 return cachefiles_daemon_range_error(cache, args);
462
463 cache->bstop_percent = bstop;
464 return 0;
465}
466
467/*
468 * set the cache directory
469 * - command: "dir <name>"
470 */
471static int cachefiles_daemon_dir(struct cachefiles_cache *cache, char *args)
472{
473 char *dir;
474
475 _enter(",%s", args);
476
477 if (!*args) {
478 kerror("Empty directory specified");
479 return -EINVAL;
480 }
481
482 if (cache->rootdirname) {
483 kerror("Second cache directory specified");
484 return -EEXIST;
485 }
486
487 dir = kstrdup(args, GFP_KERNEL);
488 if (!dir)
489 return -ENOMEM;
490
491 cache->rootdirname = dir;
492 return 0;
493}
494
495/*
496 * set the cache security context
497 * - command: "secctx <ctx>"
498 */
499static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args)
500{
501 char *secctx;
502
503 _enter(",%s", args);
504
505 if (!*args) {
506 kerror("Empty security context specified");
507 return -EINVAL;
508 }
509
510 if (cache->secctx) {
511 kerror("Second security context specified");
512 return -EINVAL;
513 }
514
515 secctx = kstrdup(args, GFP_KERNEL);
516 if (!secctx)
517 return -ENOMEM;
518
519 cache->secctx = secctx;
520 return 0;
521}
522
523/*
524 * set the cache tag
525 * - command: "tag <name>"
526 */
527static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args)
528{
529 char *tag;
530
531 _enter(",%s", args);
532
533 if (!*args) {
534 kerror("Empty tag specified");
535 return -EINVAL;
536 }
537
538 if (cache->tag)
539 return -EEXIST;
540
541 tag = kstrdup(args, GFP_KERNEL);
542 if (!tag)
543 return -ENOMEM;
544
545 cache->tag = tag;
546 return 0;
547}
548
549/*
550 * request a node in the cache be culled from the current working directory
551 * - command: "cull <name>"
552 */
553static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args)
554{
555 struct fs_struct *fs;
556 struct dentry *dir;
557 const struct cred *saved_cred;
558 int ret;
559
560 _enter(",%s", args);
561
562 if (strchr(args, '/'))
563 goto inval;
564
565 if (!test_bit(CACHEFILES_READY, &cache->flags)) {
566 kerror("cull applied to unready cache");
567 return -EIO;
568 }
569
570 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
571 kerror("cull applied to dead cache");
572 return -EIO;
573 }
574
575 /* extract the directory dentry from the cwd */
576 fs = current->fs;
577 read_lock(&fs->lock);
578 dir = dget(fs->pwd.dentry);
579 read_unlock(&fs->lock);
580
581 if (!S_ISDIR(dir->d_inode->i_mode))
582 goto notdir;
583
584 cachefiles_begin_secure(cache, &saved_cred);
585 ret = cachefiles_cull(cache, dir, args);
586 cachefiles_end_secure(cache, saved_cred);
587
588 dput(dir);
589 _leave(" = %d", ret);
590 return ret;
591
592notdir:
593 dput(dir);
594 kerror("cull command requires dirfd to be a directory");
595 return -ENOTDIR;
596
597inval:
598 kerror("cull command requires dirfd and filename");
599 return -EINVAL;
600}
601
602/*
603 * set debugging mode
604 * - command: "debug <mask>"
605 */
606static int cachefiles_daemon_debug(struct cachefiles_cache *cache, char *args)
607{
608 unsigned long mask;
609
610 _enter(",%s", args);
611
612 mask = simple_strtoul(args, &args, 0);
613 if (args[0] != '\0')
614 goto inval;
615
616 cachefiles_debug = mask;
617 _leave(" = 0");
618 return 0;
619
620inval:
621 kerror("debug command requires mask");
622 return -EINVAL;
623}
624
625/*
626 * find out whether an object in the current working directory is in use or not
627 * - command: "inuse <name>"
628 */
629static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
630{
631 struct fs_struct *fs;
632 struct dentry *dir;
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 kerror("inuse applied to unready cache");
643 return -EIO;
644 }
645
646 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
647 kerror("inuse applied to dead cache");
648 return -EIO;
649 }
650
651 /* extract the directory dentry from the cwd */
652 fs = current->fs;
653 read_lock(&fs->lock);
654 dir = dget(fs->pwd.dentry);
655 read_unlock(&fs->lock);
656
657 if (!S_ISDIR(dir->d_inode->i_mode))
658 goto notdir;
659
660 cachefiles_begin_secure(cache, &saved_cred);
661 ret = cachefiles_check_in_use(cache, dir, args);
662 cachefiles_end_secure(cache, saved_cred);
663
664 dput(dir);
665 //_leave(" = %d", ret);
666 return ret;
667
668notdir:
669 dput(dir);
670 kerror("inuse command requires dirfd to be a directory");
671 return -ENOTDIR;
672
673inval:
674 kerror("inuse command requires dirfd and filename");
675 return -EINVAL;
676}
677
678/*
679 * see if we have space for a number of pages and/or a number of files in the
680 * cache
681 */
682int cachefiles_has_space(struct cachefiles_cache *cache,
683 unsigned fnr, unsigned bnr)
684{
685 struct kstatfs stats;
686 int ret;
687
688 //_enter("{%llu,%llu,%llu,%llu,%llu,%llu},%u,%u",
689 // (unsigned long long) cache->frun,
690 // (unsigned long long) cache->fcull,
691 // (unsigned long long) cache->fstop,
692 // (unsigned long long) cache->brun,
693 // (unsigned long long) cache->bcull,
694 // (unsigned long long) cache->bstop,
695 // fnr, bnr);
696
697 /* find out how many pages of blockdev are available */
698 memset(&stats, 0, sizeof(stats));
699
700 ret = vfs_statfs(cache->mnt->mnt_root, &stats);
701 if (ret < 0) {
702 if (ret == -EIO)
703 cachefiles_io_error(cache, "statfs failed");
704 _leave(" = %d", ret);
705 return ret;
706 }
707
708 stats.f_bavail >>= cache->bshift;
709
710 //_debug("avail %llu,%llu",
711 // (unsigned long long) stats.f_ffree,
712 // (unsigned long long) stats.f_bavail);
713
714 /* see if there is sufficient space */
715 if (stats.f_ffree > fnr)
716 stats.f_ffree -= fnr;
717 else
718 stats.f_ffree = 0;
719
720 if (stats.f_bavail > bnr)
721 stats.f_bavail -= bnr;
722 else
723 stats.f_bavail = 0;
724
725 ret = -ENOBUFS;
726 if (stats.f_ffree < cache->fstop ||
727 stats.f_bavail < cache->bstop)
728 goto begin_cull;
729
730 ret = 0;
731 if (stats.f_ffree < cache->fcull ||
732 stats.f_bavail < cache->bcull)
733 goto begin_cull;
734
735 if (test_bit(CACHEFILES_CULLING, &cache->flags) &&
736 stats.f_ffree >= cache->frun &&
737 stats.f_bavail >= cache->brun &&
738 test_and_clear_bit(CACHEFILES_CULLING, &cache->flags)
739 ) {
740 _debug("cease culling");
741 cachefiles_state_changed(cache);
742 }
743
744 //_leave(" = 0");
745 return 0;
746
747begin_cull:
748 if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) {
749 _debug("### CULL CACHE ###");
750 cachefiles_state_changed(cache);
751 }
752
753 _leave(" = %d", ret);
754 return ret;
755}