blob: 452e98dd756053363a092a456ede5de373d9361f [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,
Arnd Bergmann6038f372010-08-15 18:52:59 +020058 .llseek = noop_llseek,
David Howells9ae326a2009-04-03 16:42:41 +010059};
60
61struct cachefiles_daemon_cmd {
62 char name[8];
63 int (*handler)(struct cachefiles_cache *cache, char *args);
64};
65
66static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = {
67 { "bind", cachefiles_daemon_bind },
68 { "brun", cachefiles_daemon_brun },
69 { "bcull", cachefiles_daemon_bcull },
70 { "bstop", cachefiles_daemon_bstop },
71 { "cull", cachefiles_daemon_cull },
72 { "debug", cachefiles_daemon_debug },
73 { "dir", cachefiles_daemon_dir },
74 { "frun", cachefiles_daemon_frun },
75 { "fcull", cachefiles_daemon_fcull },
76 { "fstop", cachefiles_daemon_fstop },
77 { "inuse", cachefiles_daemon_inuse },
78 { "secctx", cachefiles_daemon_secctx },
79 { "tag", cachefiles_daemon_tag },
80 { "", NULL }
81};
82
83
84/*
85 * do various checks
86 */
87static int cachefiles_daemon_open(struct inode *inode, struct file *file)
88{
89 struct cachefiles_cache *cache;
90
91 _enter("");
92
93 /* only the superuser may do this */
94 if (!capable(CAP_SYS_ADMIN))
95 return -EPERM;
96
97 /* the cachefiles device may only be open once at a time */
98 if (xchg(&cachefiles_open, 1) == 1)
99 return -EBUSY;
100
101 /* allocate a cache record */
102 cache = kzalloc(sizeof(struct cachefiles_cache), GFP_KERNEL);
103 if (!cache) {
104 cachefiles_open = 0;
105 return -ENOMEM;
106 }
107
108 mutex_init(&cache->daemon_mutex);
109 cache->active_nodes = RB_ROOT;
110 rwlock_init(&cache->active_lock);
111 init_waitqueue_head(&cache->daemon_pollwq);
112
113 /* set default caching limits
114 * - limit at 1% free space and/or free files
115 * - cull below 5% free space and/or free files
116 * - cease culling above 7% free space and/or free files
117 */
118 cache->frun_percent = 7;
119 cache->fcull_percent = 5;
120 cache->fstop_percent = 1;
121 cache->brun_percent = 7;
122 cache->bcull_percent = 5;
123 cache->bstop_percent = 1;
124
125 file->private_data = cache;
126 cache->cachefilesd = file;
127 return 0;
128}
129
130/*
131 * release a cache
132 */
133static int cachefiles_daemon_release(struct inode *inode, struct file *file)
134{
135 struct cachefiles_cache *cache = file->private_data;
136
137 _enter("");
138
139 ASSERT(cache);
140
141 set_bit(CACHEFILES_DEAD, &cache->flags);
142
143 cachefiles_daemon_unbind(cache);
144
145 ASSERT(!cache->active_nodes.rb_node);
146
147 /* clean up the control file interface */
148 cache->cachefilesd = NULL;
149 file->private_data = NULL;
150 cachefiles_open = 0;
151
152 kfree(cache);
153
154 _leave("");
155 return 0;
156}
157
158/*
159 * read the cache state
160 */
161static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
162 size_t buflen, loff_t *pos)
163{
164 struct cachefiles_cache *cache = file->private_data;
165 char buffer[256];
166 int n;
167
168 //_enter(",,%zu,", buflen);
169
170 if (!test_bit(CACHEFILES_READY, &cache->flags))
171 return 0;
172
173 /* check how much space the cache has */
174 cachefiles_has_space(cache, 0, 0);
175
176 /* summarise */
177 clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
178
179 n = snprintf(buffer, sizeof(buffer),
180 "cull=%c"
181 " frun=%llx"
182 " fcull=%llx"
183 " fstop=%llx"
184 " brun=%llx"
185 " bcull=%llx"
186 " bstop=%llx",
187 test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
188 (unsigned long long) cache->frun,
189 (unsigned long long) cache->fcull,
190 (unsigned long long) cache->fstop,
191 (unsigned long long) cache->brun,
192 (unsigned long long) cache->bcull,
193 (unsigned long long) cache->bstop
194 );
195
196 if (n > buflen)
197 return -EMSGSIZE;
198
199 if (copy_to_user(_buffer, buffer, n) != 0)
200 return -EFAULT;
201
202 return n;
203}
204
205/*
206 * command the cache
207 */
208static ssize_t cachefiles_daemon_write(struct file *file,
209 const char __user *_data,
210 size_t datalen,
211 loff_t *pos)
212{
213 const struct cachefiles_daemon_cmd *cmd;
214 struct cachefiles_cache *cache = file->private_data;
215 ssize_t ret;
216 char *data, *args, *cp;
217
218 //_enter(",,%zu,", datalen);
219
220 ASSERT(cache);
221
222 if (test_bit(CACHEFILES_DEAD, &cache->flags))
223 return -EIO;
224
225 if (datalen < 0 || datalen > PAGE_SIZE - 1)
226 return -EOPNOTSUPP;
227
228 /* drag the command string into the kernel so we can parse it */
Al Viro16e5c1f2015-12-24 00:06:05 -0500229 data = memdup_user_nul(_data, datalen);
230 if (IS_ERR(data))
231 return PTR_ERR(data);
David Howells9ae326a2009-04-03 16:42:41 +0100232
233 ret = -EINVAL;
234 if (memchr(data, '\0', datalen))
235 goto error;
236
237 /* strip any newline */
238 cp = memchr(data, '\n', datalen);
239 if (cp) {
240 if (cp == data)
241 goto error;
242
243 *cp = '\0';
244 }
245
246 /* parse the command */
247 ret = -EOPNOTSUPP;
248
249 for (args = data; *args; args++)
250 if (isspace(*args))
251 break;
252 if (*args) {
253 if (args == data)
254 goto error;
255 *args = '\0';
André Goddard Rosae7d28602009-12-14 18:01:06 -0800256 args = skip_spaces(++args);
David Howells9ae326a2009-04-03 16:42:41 +0100257 }
258
259 /* run the appropriate command handler */
260 for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
261 if (strcmp(cmd->name, data) == 0)
262 goto found_command;
263
264error:
265 kfree(data);
266 //_leave(" = %zd", ret);
267 return ret;
268
269found_command:
270 mutex_lock(&cache->daemon_mutex);
271
272 ret = -EIO;
273 if (!test_bit(CACHEFILES_DEAD, &cache->flags))
274 ret = cmd->handler(cache, args);
275
276 mutex_unlock(&cache->daemon_mutex);
277
278 if (ret == 0)
279 ret = datalen;
280 goto error;
281}
282
283/*
284 * poll for culling state
285 * - use POLLOUT to indicate culling state
286 */
287static unsigned int cachefiles_daemon_poll(struct file *file,
288 struct poll_table_struct *poll)
289{
290 struct cachefiles_cache *cache = file->private_data;
291 unsigned int mask;
292
293 poll_wait(file, &cache->daemon_pollwq, poll);
294 mask = 0;
295
296 if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
297 mask |= POLLIN;
298
299 if (test_bit(CACHEFILES_CULLING, &cache->flags))
300 mask |= POLLOUT;
301
302 return mask;
303}
304
305/*
306 * give a range error for cache space constraints
307 * - can be tail-called
308 */
309static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
310 char *args)
311{
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700312 pr_err("Free space limits must be in range 0%%<=stop<cull<run<100%%\n");
David Howells9ae326a2009-04-03 16:42:41 +0100313
314 return -EINVAL;
315}
316
317/*
318 * set the percentage of files at which to stop culling
319 * - command: "frun <N>%"
320 */
321static int cachefiles_daemon_frun(struct cachefiles_cache *cache, char *args)
322{
323 unsigned long frun;
324
325 _enter(",%s", args);
326
327 if (!*args)
328 return -EINVAL;
329
330 frun = simple_strtoul(args, &args, 10);
331 if (args[0] != '%' || args[1] != '\0')
332 return -EINVAL;
333
334 if (frun <= cache->fcull_percent || frun >= 100)
335 return cachefiles_daemon_range_error(cache, args);
336
337 cache->frun_percent = frun;
338 return 0;
339}
340
341/*
342 * set the percentage of files at which to start culling
343 * - command: "fcull <N>%"
344 */
345static int cachefiles_daemon_fcull(struct cachefiles_cache *cache, char *args)
346{
347 unsigned long fcull;
348
349 _enter(",%s", args);
350
351 if (!*args)
352 return -EINVAL;
353
354 fcull = simple_strtoul(args, &args, 10);
355 if (args[0] != '%' || args[1] != '\0')
356 return -EINVAL;
357
358 if (fcull <= cache->fstop_percent || fcull >= cache->frun_percent)
359 return cachefiles_daemon_range_error(cache, args);
360
361 cache->fcull_percent = fcull;
362 return 0;
363}
364
365/*
366 * set the percentage of files at which to stop allocating
367 * - command: "fstop <N>%"
368 */
369static int cachefiles_daemon_fstop(struct cachefiles_cache *cache, char *args)
370{
371 unsigned long fstop;
372
373 _enter(",%s", args);
374
375 if (!*args)
376 return -EINVAL;
377
378 fstop = simple_strtoul(args, &args, 10);
379 if (args[0] != '%' || args[1] != '\0')
380 return -EINVAL;
381
382 if (fstop < 0 || fstop >= cache->fcull_percent)
383 return cachefiles_daemon_range_error(cache, args);
384
385 cache->fstop_percent = fstop;
386 return 0;
387}
388
389/*
390 * set the percentage of blocks at which to stop culling
391 * - command: "brun <N>%"
392 */
393static int cachefiles_daemon_brun(struct cachefiles_cache *cache, char *args)
394{
395 unsigned long brun;
396
397 _enter(",%s", args);
398
399 if (!*args)
400 return -EINVAL;
401
402 brun = simple_strtoul(args, &args, 10);
403 if (args[0] != '%' || args[1] != '\0')
404 return -EINVAL;
405
406 if (brun <= cache->bcull_percent || brun >= 100)
407 return cachefiles_daemon_range_error(cache, args);
408
409 cache->brun_percent = brun;
410 return 0;
411}
412
413/*
414 * set the percentage of blocks at which to start culling
415 * - command: "bcull <N>%"
416 */
417static int cachefiles_daemon_bcull(struct cachefiles_cache *cache, char *args)
418{
419 unsigned long bcull;
420
421 _enter(",%s", args);
422
423 if (!*args)
424 return -EINVAL;
425
426 bcull = simple_strtoul(args, &args, 10);
427 if (args[0] != '%' || args[1] != '\0')
428 return -EINVAL;
429
430 if (bcull <= cache->bstop_percent || bcull >= cache->brun_percent)
431 return cachefiles_daemon_range_error(cache, args);
432
433 cache->bcull_percent = bcull;
434 return 0;
435}
436
437/*
438 * set the percentage of blocks at which to stop allocating
439 * - command: "bstop <N>%"
440 */
441static int cachefiles_daemon_bstop(struct cachefiles_cache *cache, char *args)
442{
443 unsigned long bstop;
444
445 _enter(",%s", args);
446
447 if (!*args)
448 return -EINVAL;
449
450 bstop = simple_strtoul(args, &args, 10);
451 if (args[0] != '%' || args[1] != '\0')
452 return -EINVAL;
453
454 if (bstop < 0 || bstop >= cache->bcull_percent)
455 return cachefiles_daemon_range_error(cache, args);
456
457 cache->bstop_percent = bstop;
458 return 0;
459}
460
461/*
462 * set the cache directory
463 * - command: "dir <name>"
464 */
465static int cachefiles_daemon_dir(struct cachefiles_cache *cache, char *args)
466{
467 char *dir;
468
469 _enter(",%s", args);
470
471 if (!*args) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700472 pr_err("Empty directory specified\n");
David Howells9ae326a2009-04-03 16:42:41 +0100473 return -EINVAL;
474 }
475
476 if (cache->rootdirname) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700477 pr_err("Second cache directory specified\n");
David Howells9ae326a2009-04-03 16:42:41 +0100478 return -EEXIST;
479 }
480
481 dir = kstrdup(args, GFP_KERNEL);
482 if (!dir)
483 return -ENOMEM;
484
485 cache->rootdirname = dir;
486 return 0;
487}
488
489/*
490 * set the cache security context
491 * - command: "secctx <ctx>"
492 */
493static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args)
494{
495 char *secctx;
496
497 _enter(",%s", args);
498
499 if (!*args) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700500 pr_err("Empty security context specified\n");
David Howells9ae326a2009-04-03 16:42:41 +0100501 return -EINVAL;
502 }
503
504 if (cache->secctx) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700505 pr_err("Second security context specified\n");
David Howells9ae326a2009-04-03 16:42:41 +0100506 return -EINVAL;
507 }
508
509 secctx = kstrdup(args, GFP_KERNEL);
510 if (!secctx)
511 return -ENOMEM;
512
513 cache->secctx = secctx;
514 return 0;
515}
516
517/*
518 * set the cache tag
519 * - command: "tag <name>"
520 */
521static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args)
522{
523 char *tag;
524
525 _enter(",%s", args);
526
527 if (!*args) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700528 pr_err("Empty tag specified\n");
David Howells9ae326a2009-04-03 16:42:41 +0100529 return -EINVAL;
530 }
531
532 if (cache->tag)
533 return -EEXIST;
534
535 tag = kstrdup(args, GFP_KERNEL);
536 if (!tag)
537 return -ENOMEM;
538
539 cache->tag = tag;
540 return 0;
541}
542
543/*
544 * request a node in the cache be culled from the current working directory
545 * - command: "cull <name>"
546 */
547static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args)
548{
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200549 struct path path;
David Howells9ae326a2009-04-03 16:42:41 +0100550 const struct cred *saved_cred;
551 int ret;
552
553 _enter(",%s", args);
554
555 if (strchr(args, '/'))
556 goto inval;
557
558 if (!test_bit(CACHEFILES_READY, &cache->flags)) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700559 pr_err("cull applied to unready cache\n");
David Howells9ae326a2009-04-03 16:42:41 +0100560 return -EIO;
561 }
562
563 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700564 pr_err("cull applied to dead cache\n");
David Howells9ae326a2009-04-03 16:42:41 +0100565 return -EIO;
566 }
567
568 /* extract the directory dentry from the cwd */
Miklos Szeredif7ad3c62010-08-10 11:41:36 +0200569 get_fs_pwd(current->fs, &path);
David Howells9ae326a2009-04-03 16:42:41 +0100570
David Howellsce40fa72015-01-29 12:02:36 +0000571 if (!d_can_lookup(path.dentry))
David Howells9ae326a2009-04-03 16:42:41 +0100572 goto notdir;
573
574 cachefiles_begin_secure(cache, &saved_cred);
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200575 ret = cachefiles_cull(cache, path.dentry, args);
David Howells9ae326a2009-04-03 16:42:41 +0100576 cachefiles_end_secure(cache, saved_cred);
577
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200578 path_put(&path);
David Howells9ae326a2009-04-03 16:42:41 +0100579 _leave(" = %d", ret);
580 return ret;
581
582notdir:
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200583 path_put(&path);
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700584 pr_err("cull command requires dirfd to be a directory\n");
David Howells9ae326a2009-04-03 16:42:41 +0100585 return -ENOTDIR;
586
587inval:
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700588 pr_err("cull command requires dirfd and filename\n");
David Howells9ae326a2009-04-03 16:42:41 +0100589 return -EINVAL;
590}
591
592/*
593 * set debugging mode
594 * - command: "debug <mask>"
595 */
596static int cachefiles_daemon_debug(struct cachefiles_cache *cache, char *args)
597{
598 unsigned long mask;
599
600 _enter(",%s", args);
601
602 mask = simple_strtoul(args, &args, 0);
603 if (args[0] != '\0')
604 goto inval;
605
606 cachefiles_debug = mask;
607 _leave(" = 0");
608 return 0;
609
610inval:
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700611 pr_err("debug command requires mask\n");
David Howells9ae326a2009-04-03 16:42:41 +0100612 return -EINVAL;
613}
614
615/*
616 * find out whether an object in the current working directory is in use or not
617 * - command: "inuse <name>"
618 */
619static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
620{
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200621 struct path path;
David Howells9ae326a2009-04-03 16:42:41 +0100622 const struct cred *saved_cred;
623 int ret;
624
625 //_enter(",%s", args);
626
627 if (strchr(args, '/'))
628 goto inval;
629
630 if (!test_bit(CACHEFILES_READY, &cache->flags)) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700631 pr_err("inuse applied to unready cache\n");
David Howells9ae326a2009-04-03 16:42:41 +0100632 return -EIO;
633 }
634
635 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700636 pr_err("inuse applied to dead cache\n");
David Howells9ae326a2009-04-03 16:42:41 +0100637 return -EIO;
638 }
639
640 /* extract the directory dentry from the cwd */
Miklos Szeredif7ad3c62010-08-10 11:41:36 +0200641 get_fs_pwd(current->fs, &path);
David Howells9ae326a2009-04-03 16:42:41 +0100642
David Howellsce40fa72015-01-29 12:02:36 +0000643 if (!d_can_lookup(path.dentry))
David Howells9ae326a2009-04-03 16:42:41 +0100644 goto notdir;
645
646 cachefiles_begin_secure(cache, &saved_cred);
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200647 ret = cachefiles_check_in_use(cache, path.dentry, args);
David Howells9ae326a2009-04-03 16:42:41 +0100648 cachefiles_end_secure(cache, saved_cred);
649
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200650 path_put(&path);
David Howells9ae326a2009-04-03 16:42:41 +0100651 //_leave(" = %d", ret);
652 return ret;
653
654notdir:
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200655 path_put(&path);
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700656 pr_err("inuse command requires dirfd to be a directory\n");
David Howells9ae326a2009-04-03 16:42:41 +0100657 return -ENOTDIR;
658
659inval:
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700660 pr_err("inuse command requires dirfd and filename\n");
David Howells9ae326a2009-04-03 16:42:41 +0100661 return -EINVAL;
662}
663
664/*
665 * see if we have space for a number of pages and/or a number of files in the
666 * cache
667 */
668int cachefiles_has_space(struct cachefiles_cache *cache,
669 unsigned fnr, unsigned bnr)
670{
671 struct kstatfs stats;
Christoph Hellwigebabe9a2010-07-07 18:53:11 +0200672 struct path path = {
673 .mnt = cache->mnt,
674 .dentry = cache->mnt->mnt_root,
675 };
David Howells9ae326a2009-04-03 16:42:41 +0100676 int ret;
677
678 //_enter("{%llu,%llu,%llu,%llu,%llu,%llu},%u,%u",
679 // (unsigned long long) cache->frun,
680 // (unsigned long long) cache->fcull,
681 // (unsigned long long) cache->fstop,
682 // (unsigned long long) cache->brun,
683 // (unsigned long long) cache->bcull,
684 // (unsigned long long) cache->bstop,
685 // fnr, bnr);
686
687 /* find out how many pages of blockdev are available */
688 memset(&stats, 0, sizeof(stats));
689
Christoph Hellwigebabe9a2010-07-07 18:53:11 +0200690 ret = vfs_statfs(&path, &stats);
David Howells9ae326a2009-04-03 16:42:41 +0100691 if (ret < 0) {
692 if (ret == -EIO)
693 cachefiles_io_error(cache, "statfs failed");
694 _leave(" = %d", ret);
695 return ret;
696 }
697
698 stats.f_bavail >>= cache->bshift;
699
700 //_debug("avail %llu,%llu",
701 // (unsigned long long) stats.f_ffree,
702 // (unsigned long long) stats.f_bavail);
703
704 /* see if there is sufficient space */
705 if (stats.f_ffree > fnr)
706 stats.f_ffree -= fnr;
707 else
708 stats.f_ffree = 0;
709
710 if (stats.f_bavail > bnr)
711 stats.f_bavail -= bnr;
712 else
713 stats.f_bavail = 0;
714
715 ret = -ENOBUFS;
716 if (stats.f_ffree < cache->fstop ||
717 stats.f_bavail < cache->bstop)
718 goto begin_cull;
719
720 ret = 0;
721 if (stats.f_ffree < cache->fcull ||
722 stats.f_bavail < cache->bcull)
723 goto begin_cull;
724
725 if (test_bit(CACHEFILES_CULLING, &cache->flags) &&
726 stats.f_ffree >= cache->frun &&
727 stats.f_bavail >= cache->brun &&
728 test_and_clear_bit(CACHEFILES_CULLING, &cache->flags)
729 ) {
730 _debug("cease culling");
731 cachefiles_state_changed(cache);
732 }
733
734 //_leave(" = 0");
735 return 0;
736
737begin_cull:
738 if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) {
739 _debug("### CULL CACHE ###");
740 cachefiles_state_changed(cache);
741 }
742
743 _leave(" = %d", ret);
744 return ret;
745}