blob: f601def05bdf00663f5b1666514e1810068e1b19 [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 */
229 data = kmalloc(datalen + 1, GFP_KERNEL);
230 if (!data)
231 return -ENOMEM;
232
233 ret = -EFAULT;
234 if (copy_from_user(data, _data, datalen) != 0)
235 goto error;
236
237 data[datalen] = '\0';
238
239 ret = -EINVAL;
240 if (memchr(data, '\0', datalen))
241 goto error;
242
243 /* strip any newline */
244 cp = memchr(data, '\n', datalen);
245 if (cp) {
246 if (cp == data)
247 goto error;
248
249 *cp = '\0';
250 }
251
252 /* parse the command */
253 ret = -EOPNOTSUPP;
254
255 for (args = data; *args; args++)
256 if (isspace(*args))
257 break;
258 if (*args) {
259 if (args == data)
260 goto error;
261 *args = '\0';
André Goddard Rosae7d28602009-12-14 18:01:06 -0800262 args = skip_spaces(++args);
David Howells9ae326a2009-04-03 16:42:41 +0100263 }
264
265 /* run the appropriate command handler */
266 for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
267 if (strcmp(cmd->name, data) == 0)
268 goto found_command;
269
270error:
271 kfree(data);
272 //_leave(" = %zd", ret);
273 return ret;
274
275found_command:
276 mutex_lock(&cache->daemon_mutex);
277
278 ret = -EIO;
279 if (!test_bit(CACHEFILES_DEAD, &cache->flags))
280 ret = cmd->handler(cache, args);
281
282 mutex_unlock(&cache->daemon_mutex);
283
284 if (ret == 0)
285 ret = datalen;
286 goto error;
287}
288
289/*
290 * poll for culling state
291 * - use POLLOUT to indicate culling state
292 */
293static unsigned int cachefiles_daemon_poll(struct file *file,
294 struct poll_table_struct *poll)
295{
296 struct cachefiles_cache *cache = file->private_data;
297 unsigned int mask;
298
299 poll_wait(file, &cache->daemon_pollwq, poll);
300 mask = 0;
301
302 if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
303 mask |= POLLIN;
304
305 if (test_bit(CACHEFILES_CULLING, &cache->flags))
306 mask |= POLLOUT;
307
308 return mask;
309}
310
311/*
312 * give a range error for cache space constraints
313 * - can be tail-called
314 */
315static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
316 char *args)
317{
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700318 pr_err("Free space limits must be in range 0%%<=stop<cull<run<100%%\n");
David Howells9ae326a2009-04-03 16:42:41 +0100319
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) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700478 pr_err("Empty directory specified\n");
David Howells9ae326a2009-04-03 16:42:41 +0100479 return -EINVAL;
480 }
481
482 if (cache->rootdirname) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700483 pr_err("Second cache directory specified\n");
David Howells9ae326a2009-04-03 16:42:41 +0100484 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) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700506 pr_err("Empty security context specified\n");
David Howells9ae326a2009-04-03 16:42:41 +0100507 return -EINVAL;
508 }
509
510 if (cache->secctx) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700511 pr_err("Second security context specified\n");
David Howells9ae326a2009-04-03 16:42:41 +0100512 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) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700534 pr_err("Empty tag specified\n");
David Howells9ae326a2009-04-03 16:42:41 +0100535 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{
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200555 struct path path;
David Howells9ae326a2009-04-03 16:42:41 +0100556 const struct cred *saved_cred;
557 int ret;
558
559 _enter(",%s", args);
560
561 if (strchr(args, '/'))
562 goto inval;
563
564 if (!test_bit(CACHEFILES_READY, &cache->flags)) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700565 pr_err("cull applied to unready cache\n");
David Howells9ae326a2009-04-03 16:42:41 +0100566 return -EIO;
567 }
568
569 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700570 pr_err("cull applied to dead cache\n");
David Howells9ae326a2009-04-03 16:42:41 +0100571 return -EIO;
572 }
573
574 /* extract the directory dentry from the cwd */
Miklos Szeredif7ad3c62010-08-10 11:41:36 +0200575 get_fs_pwd(current->fs, &path);
David Howells9ae326a2009-04-03 16:42:41 +0100576
David Howellsce40fa72015-01-29 12:02:36 +0000577 if (!d_can_lookup(path.dentry))
David Howells9ae326a2009-04-03 16:42:41 +0100578 goto notdir;
579
580 cachefiles_begin_secure(cache, &saved_cred);
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200581 ret = cachefiles_cull(cache, path.dentry, args);
David Howells9ae326a2009-04-03 16:42:41 +0100582 cachefiles_end_secure(cache, saved_cred);
583
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200584 path_put(&path);
David Howells9ae326a2009-04-03 16:42:41 +0100585 _leave(" = %d", ret);
586 return ret;
587
588notdir:
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200589 path_put(&path);
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700590 pr_err("cull command requires dirfd to be a directory\n");
David Howells9ae326a2009-04-03 16:42:41 +0100591 return -ENOTDIR;
592
593inval:
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700594 pr_err("cull command requires dirfd and filename\n");
David Howells9ae326a2009-04-03 16:42:41 +0100595 return -EINVAL;
596}
597
598/*
599 * set debugging mode
600 * - command: "debug <mask>"
601 */
602static int cachefiles_daemon_debug(struct cachefiles_cache *cache, char *args)
603{
604 unsigned long mask;
605
606 _enter(",%s", args);
607
608 mask = simple_strtoul(args, &args, 0);
609 if (args[0] != '\0')
610 goto inval;
611
612 cachefiles_debug = mask;
613 _leave(" = 0");
614 return 0;
615
616inval:
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700617 pr_err("debug command requires mask\n");
David Howells9ae326a2009-04-03 16:42:41 +0100618 return -EINVAL;
619}
620
621/*
622 * find out whether an object in the current working directory is in use or not
623 * - command: "inuse <name>"
624 */
625static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
626{
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200627 struct path path;
David Howells9ae326a2009-04-03 16:42:41 +0100628 const struct cred *saved_cred;
629 int ret;
630
631 //_enter(",%s", args);
632
633 if (strchr(args, '/'))
634 goto inval;
635
636 if (!test_bit(CACHEFILES_READY, &cache->flags)) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700637 pr_err("inuse applied to unready cache\n");
David Howells9ae326a2009-04-03 16:42:41 +0100638 return -EIO;
639 }
640
641 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700642 pr_err("inuse applied to dead cache\n");
David Howells9ae326a2009-04-03 16:42:41 +0100643 return -EIO;
644 }
645
646 /* extract the directory dentry from the cwd */
Miklos Szeredif7ad3c62010-08-10 11:41:36 +0200647 get_fs_pwd(current->fs, &path);
David Howells9ae326a2009-04-03 16:42:41 +0100648
David Howellsce40fa72015-01-29 12:02:36 +0000649 if (!d_can_lookup(path.dentry))
David Howells9ae326a2009-04-03 16:42:41 +0100650 goto notdir;
651
652 cachefiles_begin_secure(cache, &saved_cred);
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200653 ret = cachefiles_check_in_use(cache, path.dentry, args);
David Howells9ae326a2009-04-03 16:42:41 +0100654 cachefiles_end_secure(cache, saved_cred);
655
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200656 path_put(&path);
David Howells9ae326a2009-04-03 16:42:41 +0100657 //_leave(" = %d", ret);
658 return ret;
659
660notdir:
Miklos Szeredi542ce7a2010-08-10 11:41:35 +0200661 path_put(&path);
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700662 pr_err("inuse command requires dirfd to be a directory\n");
David Howells9ae326a2009-04-03 16:42:41 +0100663 return -ENOTDIR;
664
665inval:
Fabian Frederick6ff66ac2014-09-25 16:05:27 -0700666 pr_err("inuse command requires dirfd and filename\n");
David Howells9ae326a2009-04-03 16:42:41 +0100667 return -EINVAL;
668}
669
670/*
671 * see if we have space for a number of pages and/or a number of files in the
672 * cache
673 */
674int cachefiles_has_space(struct cachefiles_cache *cache,
675 unsigned fnr, unsigned bnr)
676{
677 struct kstatfs stats;
Christoph Hellwigebabe9a2010-07-07 18:53:11 +0200678 struct path path = {
679 .mnt = cache->mnt,
680 .dentry = cache->mnt->mnt_root,
681 };
David Howells9ae326a2009-04-03 16:42:41 +0100682 int ret;
683
684 //_enter("{%llu,%llu,%llu,%llu,%llu,%llu},%u,%u",
685 // (unsigned long long) cache->frun,
686 // (unsigned long long) cache->fcull,
687 // (unsigned long long) cache->fstop,
688 // (unsigned long long) cache->brun,
689 // (unsigned long long) cache->bcull,
690 // (unsigned long long) cache->bstop,
691 // fnr, bnr);
692
693 /* find out how many pages of blockdev are available */
694 memset(&stats, 0, sizeof(stats));
695
Christoph Hellwigebabe9a2010-07-07 18:53:11 +0200696 ret = vfs_statfs(&path, &stats);
David Howells9ae326a2009-04-03 16:42:41 +0100697 if (ret < 0) {
698 if (ret == -EIO)
699 cachefiles_io_error(cache, "statfs failed");
700 _leave(" = %d", ret);
701 return ret;
702 }
703
704 stats.f_bavail >>= cache->bshift;
705
706 //_debug("avail %llu,%llu",
707 // (unsigned long long) stats.f_ffree,
708 // (unsigned long long) stats.f_bavail);
709
710 /* see if there is sufficient space */
711 if (stats.f_ffree > fnr)
712 stats.f_ffree -= fnr;
713 else
714 stats.f_ffree = 0;
715
716 if (stats.f_bavail > bnr)
717 stats.f_bavail -= bnr;
718 else
719 stats.f_bavail = 0;
720
721 ret = -ENOBUFS;
722 if (stats.f_ffree < cache->fstop ||
723 stats.f_bavail < cache->bstop)
724 goto begin_cull;
725
726 ret = 0;
727 if (stats.f_ffree < cache->fcull ||
728 stats.f_bavail < cache->bcull)
729 goto begin_cull;
730
731 if (test_bit(CACHEFILES_CULLING, &cache->flags) &&
732 stats.f_ffree >= cache->frun &&
733 stats.f_bavail >= cache->brun &&
734 test_and_clear_bit(CACHEFILES_CULLING, &cache->flags)
735 ) {
736 _debug("cease culling");
737 cachefiles_state_changed(cache);
738 }
739
740 //_leave(" = 0");
741 return 0;
742
743begin_cull:
744 if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) {
745 _debug("### CULL CACHE ###");
746 cachefiles_state_changed(cache);
747 }
748
749 _leave(" = %d", ret);
750 return ret;
751}