1 /* CacheFiles path walking and related routines
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/sched.h>
14 #include <linux/file.h>
15 #include <linux/fs.h>
16 #include <linux/fsnotify.h>
17 #include <linux/quotaops.h>
18 #include <linux/xattr.h>
19 #include <linux/mount.h>
20 #include <linux/namei.h>
21 #include <linux/security.h>
22 #include <linux/slab.h>
23 #include "internal.h"
24
25 #define CACHEFILES_KEYBUF_SIZE 512
26
27 /*
28 * dump debugging info about an object
29 */
30 static noinline
__cachefiles_printk_object(struct cachefiles_object * object,const char * prefix,u8 * keybuf)31 void __cachefiles_printk_object(struct cachefiles_object *object,
32 const char *prefix,
33 u8 *keybuf)
34 {
35 struct fscache_cookie *cookie;
36 unsigned keylen, loop;
37
38 printk(KERN_ERR "%sobject: OBJ%x\n",
39 prefix, object->fscache.debug_id);
40 printk(KERN_ERR "%sobjstate=%s fl=%lx wbusy=%x ev=%lx[%lx]\n",
41 prefix, fscache_object_states[object->fscache.state],
42 object->fscache.flags, work_busy(&object->fscache.work),
43 object->fscache.events,
44 object->fscache.event_mask & FSCACHE_OBJECT_EVENTS_MASK);
45 printk(KERN_ERR "%sops=%u inp=%u exc=%u\n",
46 prefix, object->fscache.n_ops, object->fscache.n_in_progress,
47 object->fscache.n_exclusive);
48 printk(KERN_ERR "%sparent=%p\n",
49 prefix, object->fscache.parent);
50
51 spin_lock(&object->fscache.lock);
52 cookie = object->fscache.cookie;
53 if (cookie) {
54 printk(KERN_ERR "%scookie=%p [pr=%p nd=%p fl=%lx]\n",
55 prefix,
56 object->fscache.cookie,
57 object->fscache.cookie->parent,
58 object->fscache.cookie->netfs_data,
59 object->fscache.cookie->flags);
60 if (keybuf)
61 keylen = cookie->def->get_key(cookie->netfs_data, keybuf,
62 CACHEFILES_KEYBUF_SIZE);
63 else
64 keylen = 0;
65 } else {
66 printk(KERN_ERR "%scookie=NULL\n", prefix);
67 keylen = 0;
68 }
69 spin_unlock(&object->fscache.lock);
70
71 if (keylen) {
72 printk(KERN_ERR "%skey=[%u] '", prefix, keylen);
73 for (loop = 0; loop < keylen; loop++)
74 printk("%02x", keybuf[loop]);
75 printk("'\n");
76 }
77 }
78
79 /*
80 * dump debugging info about a pair of objects
81 */
cachefiles_printk_object(struct cachefiles_object * object,struct cachefiles_object * xobject)82 static noinline void cachefiles_printk_object(struct cachefiles_object *object,
83 struct cachefiles_object *xobject)
84 {
85 u8 *keybuf;
86
87 keybuf = kmalloc(CACHEFILES_KEYBUF_SIZE, GFP_NOIO);
88 if (object)
89 __cachefiles_printk_object(object, "", keybuf);
90 if (xobject)
91 __cachefiles_printk_object(xobject, "x", keybuf);
92 kfree(keybuf);
93 }
94
95 /*
96 * mark the owner of a dentry, if there is one, to indicate that that dentry
97 * has been preemptively deleted
98 * - the caller must hold the i_mutex on the dentry's parent as required to
99 * call vfs_unlink(), vfs_rmdir() or vfs_rename()
100 */
cachefiles_mark_object_buried(struct cachefiles_cache * cache,struct dentry * dentry)101 static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
102 struct dentry *dentry)
103 {
104 struct cachefiles_object *object;
105 struct rb_node *p;
106
107 _enter(",'%*.*s'",
108 dentry->d_name.len, dentry->d_name.len, dentry->d_name.name);
109
110 write_lock(&cache->active_lock);
111
112 p = cache->active_nodes.rb_node;
113 while (p) {
114 object = rb_entry(p, struct cachefiles_object, active_node);
115 if (object->dentry > dentry)
116 p = p->rb_left;
117 else if (object->dentry < dentry)
118 p = p->rb_right;
119 else
120 goto found_dentry;
121 }
122
123 write_unlock(&cache->active_lock);
124 _leave(" [no owner]");
125 return;
126
127 /* found the dentry for */
128 found_dentry:
129 kdebug("preemptive burial: OBJ%x [%s] %p",
130 object->fscache.debug_id,
131 fscache_object_states[object->fscache.state],
132 dentry);
133
134 if (object->fscache.state < FSCACHE_OBJECT_DYING) {
135 printk(KERN_ERR "\n");
136 printk(KERN_ERR "CacheFiles: Error:"
137 " Can't preemptively bury live object\n");
138 cachefiles_printk_object(object, NULL);
139 } else if (test_and_set_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
140 printk(KERN_ERR "CacheFiles: Error:"
141 " Object already preemptively buried\n");
142 }
143
144 write_unlock(&cache->active_lock);
145 _leave(" [owner marked]");
146 }
147
148 /*
149 * record the fact that an object is now active
150 */
cachefiles_mark_object_active(struct cachefiles_cache * cache,struct cachefiles_object * object)151 static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
152 struct cachefiles_object *object)
153 {
154 struct cachefiles_object *xobject;
155 struct rb_node **_p, *_parent = NULL;
156 struct dentry *dentry;
157
158 _enter(",%p", object);
159
160 try_again:
161 write_lock(&cache->active_lock);
162
163 if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
164 printk(KERN_ERR "CacheFiles: Error: Object already active\n");
165 cachefiles_printk_object(object, NULL);
166 BUG();
167 }
168
169 dentry = object->dentry;
170 _p = &cache->active_nodes.rb_node;
171 while (*_p) {
172 _parent = *_p;
173 xobject = rb_entry(_parent,
174 struct cachefiles_object, active_node);
175
176 ASSERT(xobject != object);
177
178 if (xobject->dentry > dentry)
179 _p = &(*_p)->rb_left;
180 else if (xobject->dentry < dentry)
181 _p = &(*_p)->rb_right;
182 else
183 goto wait_for_old_object;
184 }
185
186 rb_link_node(&object->active_node, _parent, _p);
187 rb_insert_color(&object->active_node, &cache->active_nodes);
188
189 write_unlock(&cache->active_lock);
190 _leave(" = 0");
191 return 0;
192
193 /* an old object from a previous incarnation is hogging the slot - we
194 * need to wait for it to be destroyed */
195 wait_for_old_object:
196 if (xobject->fscache.state < FSCACHE_OBJECT_DYING) {
197 printk(KERN_ERR "\n");
198 printk(KERN_ERR "CacheFiles: Error:"
199 " Unexpected object collision\n");
200 cachefiles_printk_object(object, xobject);
201 BUG();
202 }
203 atomic_inc(&xobject->usage);
204 write_unlock(&cache->active_lock);
205
206 if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
207 wait_queue_head_t *wq;
208
209 signed long timeout = 60 * HZ;
210 wait_queue_t wait;
211 bool requeue;
212
213 /* if the object we're waiting for is queued for processing,
214 * then just put ourselves on the queue behind it */
215 if (work_pending(&xobject->fscache.work)) {
216 _debug("queue OBJ%x behind OBJ%x immediately",
217 object->fscache.debug_id,
218 xobject->fscache.debug_id);
219 goto requeue;
220 }
221
222 /* otherwise we sleep until either the object we're waiting for
223 * is done, or the fscache_object is congested */
224 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
225 init_wait(&wait);
226 requeue = false;
227 do {
228 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
229 if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
230 break;
231
232 requeue = fscache_object_sleep_till_congested(&timeout);
233 } while (timeout > 0 && !requeue);
234 finish_wait(wq, &wait);
235
236 if (requeue &&
237 test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
238 _debug("queue OBJ%x behind OBJ%x after wait",
239 object->fscache.debug_id,
240 xobject->fscache.debug_id);
241 goto requeue;
242 }
243
244 if (timeout <= 0) {
245 printk(KERN_ERR "\n");
246 printk(KERN_ERR "CacheFiles: Error: Overlong"
247 " wait for old active object to go away\n");
248 cachefiles_printk_object(object, xobject);
249 goto requeue;
250 }
251 }
252
253 ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
254
255 cache->cache.ops->put_object(&xobject->fscache);
256 goto try_again;
257
258 requeue:
259 clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
260 cache->cache.ops->put_object(&xobject->fscache);
261 _leave(" = -ETIMEDOUT");
262 return -ETIMEDOUT;
263 }
264
265 /*
266 * delete an object representation from the cache
267 * - file backed objects are unlinked
268 * - directory backed objects are stuffed into the graveyard for userspace to
269 * delete
270 * - unlocks the directory mutex
271 */
cachefiles_bury_object(struct cachefiles_cache * cache,struct dentry * dir,struct dentry * rep,bool preemptive)272 static int cachefiles_bury_object(struct cachefiles_cache *cache,
273 struct dentry *dir,
274 struct dentry *rep,
275 bool preemptive)
276 {
277 struct dentry *grave, *trap;
278 struct path path, path_to_graveyard;
279 char nbuffer[8 + 8 + 1];
280 int ret;
281
282 _enter(",'%*.*s','%*.*s'",
283 dir->d_name.len, dir->d_name.len, dir->d_name.name,
284 rep->d_name.len, rep->d_name.len, rep->d_name.name);
285
286 _debug("remove %p from %p", rep, dir);
287
288 /* non-directories can just be unlinked */
289 if (!S_ISDIR(rep->d_inode->i_mode)) {
290 _debug("unlink stale object");
291
292 path.mnt = cache->mnt;
293 path.dentry = dir;
294 ret = security_path_unlink(&path, rep);
295 if (ret < 0) {
296 cachefiles_io_error(cache, "Unlink security error");
297 } else {
298 ret = vfs_unlink(dir->d_inode, rep);
299
300 if (preemptive)
301 cachefiles_mark_object_buried(cache, rep);
302 }
303
304 mutex_unlock(&dir->d_inode->i_mutex);
305
306 if (ret == -EIO)
307 cachefiles_io_error(cache, "Unlink failed");
308
309 _leave(" = %d", ret);
310 return ret;
311 }
312
313 /* directories have to be moved to the graveyard */
314 _debug("move stale object to graveyard");
315 mutex_unlock(&dir->d_inode->i_mutex);
316
317 try_again:
318 /* first step is to make up a grave dentry in the graveyard */
319 sprintf(nbuffer, "%08x%08x",
320 (uint32_t) get_seconds(),
321 (uint32_t) atomic_inc_return(&cache->gravecounter));
322
323 /* do the multiway lock magic */
324 trap = lock_rename(cache->graveyard, dir);
325
326 /* do some checks before getting the grave dentry */
327 if (rep->d_parent != dir) {
328 /* the entry was probably culled when we dropped the parent dir
329 * lock */
330 unlock_rename(cache->graveyard, dir);
331 _leave(" = 0 [culled?]");
332 return 0;
333 }
334
335 if (!S_ISDIR(cache->graveyard->d_inode->i_mode)) {
336 unlock_rename(cache->graveyard, dir);
337 cachefiles_io_error(cache, "Graveyard no longer a directory");
338 return -EIO;
339 }
340
341 if (trap == rep) {
342 unlock_rename(cache->graveyard, dir);
343 cachefiles_io_error(cache, "May not make directory loop");
344 return -EIO;
345 }
346
347 if (d_mountpoint(rep)) {
348 unlock_rename(cache->graveyard, dir);
349 cachefiles_io_error(cache, "Mountpoint in cache");
350 return -EIO;
351 }
352
353 grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
354 if (IS_ERR(grave)) {
355 unlock_rename(cache->graveyard, dir);
356
357 if (PTR_ERR(grave) == -ENOMEM) {
358 _leave(" = -ENOMEM");
359 return -ENOMEM;
360 }
361
362 cachefiles_io_error(cache, "Lookup error %ld",
363 PTR_ERR(grave));
364 return -EIO;
365 }
366
367 if (grave->d_inode) {
368 unlock_rename(cache->graveyard, dir);
369 dput(grave);
370 grave = NULL;
371 cond_resched();
372 goto try_again;
373 }
374
375 if (d_mountpoint(grave)) {
376 unlock_rename(cache->graveyard, dir);
377 dput(grave);
378 cachefiles_io_error(cache, "Mountpoint in graveyard");
379 return -EIO;
380 }
381
382 /* target should not be an ancestor of source */
383 if (trap == grave) {
384 unlock_rename(cache->graveyard, dir);
385 dput(grave);
386 cachefiles_io_error(cache, "May not make directory loop");
387 return -EIO;
388 }
389
390 /* attempt the rename */
391 path.mnt = cache->mnt;
392 path.dentry = dir;
393 path_to_graveyard.mnt = cache->mnt;
394 path_to_graveyard.dentry = cache->graveyard;
395 ret = security_path_rename(&path, rep, &path_to_graveyard, grave);
396 if (ret < 0) {
397 cachefiles_io_error(cache, "Rename security error %d", ret);
398 } else {
399 ret = vfs_rename(dir->d_inode, rep,
400 cache->graveyard->d_inode, grave);
401 if (ret != 0 && ret != -ENOMEM)
402 cachefiles_io_error(cache,
403 "Rename failed with error %d", ret);
404
405 if (preemptive)
406 cachefiles_mark_object_buried(cache, rep);
407 }
408
409 unlock_rename(cache->graveyard, dir);
410 dput(grave);
411 _leave(" = 0");
412 return 0;
413 }
414
415 /*
416 * delete an object representation from the cache
417 */
cachefiles_delete_object(struct cachefiles_cache * cache,struct cachefiles_object * object)418 int cachefiles_delete_object(struct cachefiles_cache *cache,
419 struct cachefiles_object *object)
420 {
421 struct dentry *dir;
422 int ret;
423
424 _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
425
426 ASSERT(object->dentry);
427 ASSERT(object->dentry->d_inode);
428 ASSERT(object->dentry->d_parent);
429
430 dir = dget_parent(object->dentry);
431
432 mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
433
434 if (test_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
435 /* object allocation for the same key preemptively deleted this
436 * object's file so that it could create its own file */
437 _debug("object preemptively buried");
438 mutex_unlock(&dir->d_inode->i_mutex);
439 ret = 0;
440 } else {
441 /* we need to check that our parent is _still_ our parent - it
442 * may have been renamed */
443 if (dir == object->dentry->d_parent) {
444 ret = cachefiles_bury_object(cache, dir,
445 object->dentry, false);
446 } else {
447 /* it got moved, presumably by cachefilesd culling it,
448 * so it's no longer in the key path and we can ignore
449 * it */
450 mutex_unlock(&dir->d_inode->i_mutex);
451 ret = 0;
452 }
453 }
454
455 dput(dir);
456 _leave(" = %d", ret);
457 return ret;
458 }
459
460 /*
461 * walk from the parent object to the child object through the backing
462 * filesystem, creating directories as we go
463 */
cachefiles_walk_to_object(struct cachefiles_object * parent,struct cachefiles_object * object,const char * key,struct cachefiles_xattr * auxdata)464 int cachefiles_walk_to_object(struct cachefiles_object *parent,
465 struct cachefiles_object *object,
466 const char *key,
467 struct cachefiles_xattr *auxdata)
468 {
469 struct cachefiles_cache *cache;
470 struct dentry *dir, *next = NULL;
471 struct path path;
472 unsigned long start;
473 const char *name;
474 int ret, nlen;
475
476 _enter("OBJ%x{%p},OBJ%x,%s,",
477 parent->fscache.debug_id, parent->dentry,
478 object->fscache.debug_id, key);
479
480 cache = container_of(parent->fscache.cache,
481 struct cachefiles_cache, cache);
482 path.mnt = cache->mnt;
483
484 ASSERT(parent->dentry);
485 ASSERT(parent->dentry->d_inode);
486
487 if (!(S_ISDIR(parent->dentry->d_inode->i_mode))) {
488 // TODO: convert file to dir
489 _leave("looking up in none directory");
490 return -ENOBUFS;
491 }
492
493 dir = dget(parent->dentry);
494
495 advance:
496 /* attempt to transit the first directory component */
497 name = key;
498 nlen = strlen(key);
499
500 /* key ends in a double NUL */
501 key = key + nlen + 1;
502 if (!*key)
503 key = NULL;
504
505 lookup_again:
506 /* search the current directory for the element name */
507 _debug("lookup '%s'", name);
508
509 mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
510
511 start = jiffies;
512 next = lookup_one_len(name, dir, nlen);
513 cachefiles_hist(cachefiles_lookup_histogram, start);
514 if (IS_ERR(next))
515 goto lookup_error;
516
517 _debug("next -> %p %s", next, next->d_inode ? "positive" : "negative");
518
519 if (!key)
520 object->new = !next->d_inode;
521
522 /* if this element of the path doesn't exist, then the lookup phase
523 * failed, and we can release any readers in the certain knowledge that
524 * there's nothing for them to actually read */
525 if (!next->d_inode)
526 fscache_object_lookup_negative(&object->fscache);
527
528 /* we need to create the object if it's negative */
529 if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
530 /* index objects and intervening tree levels must be subdirs */
531 if (!next->d_inode) {
532 ret = cachefiles_has_space(cache, 1, 0);
533 if (ret < 0)
534 goto create_error;
535
536 path.dentry = dir;
537 ret = security_path_mkdir(&path, next, 0);
538 if (ret < 0)
539 goto create_error;
540 start = jiffies;
541 ret = vfs_mkdir(dir->d_inode, next, 0);
542 cachefiles_hist(cachefiles_mkdir_histogram, start);
543 if (ret < 0)
544 goto create_error;
545
546 ASSERT(next->d_inode);
547
548 _debug("mkdir -> %p{%p{ino=%lu}}",
549 next, next->d_inode, next->d_inode->i_ino);
550
551 } else if (!S_ISDIR(next->d_inode->i_mode)) {
552 kerror("inode %lu is not a directory",
553 next->d_inode->i_ino);
554 ret = -ENOBUFS;
555 goto error;
556 }
557
558 } else {
559 /* non-index objects start out life as files */
560 if (!next->d_inode) {
561 ret = cachefiles_has_space(cache, 1, 0);
562 if (ret < 0)
563 goto create_error;
564
565 path.dentry = dir;
566 ret = security_path_mknod(&path, next, S_IFREG, 0);
567 if (ret < 0)
568 goto create_error;
569 start = jiffies;
570 ret = vfs_create(dir->d_inode, next, S_IFREG, NULL);
571 cachefiles_hist(cachefiles_create_histogram, start);
572 if (ret < 0)
573 goto create_error;
574
575 ASSERT(next->d_inode);
576
577 _debug("create -> %p{%p{ino=%lu}}",
578 next, next->d_inode, next->d_inode->i_ino);
579
580 } else if (!S_ISDIR(next->d_inode->i_mode) &&
581 !S_ISREG(next->d_inode->i_mode)
582 ) {
583 kerror("inode %lu is not a file or directory",
584 next->d_inode->i_ino);
585 ret = -ENOBUFS;
586 goto error;
587 }
588 }
589
590 /* process the next component */
591 if (key) {
592 _debug("advance");
593 mutex_unlock(&dir->d_inode->i_mutex);
594 dput(dir);
595 dir = next;
596 next = NULL;
597 goto advance;
598 }
599
600 /* we've found the object we were looking for */
601 object->dentry = next;
602
603 /* if we've found that the terminal object exists, then we need to
604 * check its attributes and delete it if it's out of date */
605 if (!object->new) {
606 _debug("validate '%*.*s'",
607 next->d_name.len, next->d_name.len, next->d_name.name);
608
609 ret = cachefiles_check_object_xattr(object, auxdata);
610 if (ret == -ESTALE) {
611 /* delete the object (the deleter drops the directory
612 * mutex) */
613 object->dentry = NULL;
614
615 ret = cachefiles_bury_object(cache, dir, next, true);
616 dput(next);
617 next = NULL;
618
619 if (ret < 0)
620 goto delete_error;
621
622 _debug("redo lookup");
623 goto lookup_again;
624 }
625 }
626
627 /* note that we're now using this object */
628 ret = cachefiles_mark_object_active(cache, object);
629
630 mutex_unlock(&dir->d_inode->i_mutex);
631 dput(dir);
632 dir = NULL;
633
634 if (ret == -ETIMEDOUT)
635 goto mark_active_timed_out;
636
637 _debug("=== OBTAINED_OBJECT ===");
638
639 if (object->new) {
640 /* attach data to a newly constructed terminal object */
641 ret = cachefiles_set_object_xattr(object, auxdata);
642 if (ret < 0)
643 goto check_error;
644 } else {
645 /* always update the atime on an object we've just looked up
646 * (this is used to keep track of culling, and atimes are only
647 * updated by read, write and readdir but not lookup or
648 * open) */
649 touch_atime(cache->mnt, next);
650 }
651
652 /* open a file interface onto a data file */
653 if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
654 if (S_ISREG(object->dentry->d_inode->i_mode)) {
655 const struct address_space_operations *aops;
656
657 ret = -EPERM;
658 aops = object->dentry->d_inode->i_mapping->a_ops;
659 if (!aops->bmap)
660 goto check_error;
661
662 object->backer = object->dentry;
663 } else {
664 BUG(); // TODO: open file in data-class subdir
665 }
666 }
667
668 object->new = 0;
669 fscache_obtained_object(&object->fscache);
670
671 _leave(" = 0 [%lu]", object->dentry->d_inode->i_ino);
672 return 0;
673
674 create_error:
675 _debug("create error %d", ret);
676 if (ret == -EIO)
677 cachefiles_io_error(cache, "Create/mkdir failed");
678 goto error;
679
680 mark_active_timed_out:
681 _debug("mark active timed out");
682 goto release_dentry;
683
684 check_error:
685 _debug("check error %d", ret);
686 write_lock(&cache->active_lock);
687 rb_erase(&object->active_node, &cache->active_nodes);
688 clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
689 wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
690 write_unlock(&cache->active_lock);
691 release_dentry:
692 dput(object->dentry);
693 object->dentry = NULL;
694 goto error_out;
695
696 delete_error:
697 _debug("delete error %d", ret);
698 goto error_out2;
699
700 lookup_error:
701 _debug("lookup error %ld", PTR_ERR(next));
702 ret = PTR_ERR(next);
703 if (ret == -EIO)
704 cachefiles_io_error(cache, "Lookup failed");
705 next = NULL;
706 error:
707 mutex_unlock(&dir->d_inode->i_mutex);
708 dput(next);
709 error_out2:
710 dput(dir);
711 error_out:
712 _leave(" = error %d", -ret);
713 return ret;
714 }
715
716 /*
717 * get a subdirectory
718 */
cachefiles_get_directory(struct cachefiles_cache * cache,struct dentry * dir,const char * dirname)719 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
720 struct dentry *dir,
721 const char *dirname)
722 {
723 struct dentry *subdir;
724 unsigned long start;
725 struct path path;
726 int ret;
727
728 _enter(",,%s", dirname);
729
730 /* search the current directory for the element name */
731 mutex_lock(&dir->d_inode->i_mutex);
732
733 start = jiffies;
734 subdir = lookup_one_len(dirname, dir, strlen(dirname));
735 cachefiles_hist(cachefiles_lookup_histogram, start);
736 if (IS_ERR(subdir)) {
737 if (PTR_ERR(subdir) == -ENOMEM)
738 goto nomem_d_alloc;
739 goto lookup_error;
740 }
741
742 _debug("subdir -> %p %s",
743 subdir, subdir->d_inode ? "positive" : "negative");
744
745 /* we need to create the subdir if it doesn't exist yet */
746 if (!subdir->d_inode) {
747 ret = cachefiles_has_space(cache, 1, 0);
748 if (ret < 0)
749 goto mkdir_error;
750
751 _debug("attempt mkdir");
752
753 path.mnt = cache->mnt;
754 path.dentry = dir;
755 ret = security_path_mkdir(&path, subdir, 0700);
756 if (ret < 0)
757 goto mkdir_error;
758 ret = vfs_mkdir(dir->d_inode, subdir, 0700);
759 if (ret < 0)
760 goto mkdir_error;
761
762 ASSERT(subdir->d_inode);
763
764 _debug("mkdir -> %p{%p{ino=%lu}}",
765 subdir,
766 subdir->d_inode,
767 subdir->d_inode->i_ino);
768 }
769
770 mutex_unlock(&dir->d_inode->i_mutex);
771
772 /* we need to make sure the subdir is a directory */
773 ASSERT(subdir->d_inode);
774
775 if (!S_ISDIR(subdir->d_inode->i_mode)) {
776 kerror("%s is not a directory", dirname);
777 ret = -EIO;
778 goto check_error;
779 }
780
781 ret = -EPERM;
782 if (!subdir->d_inode->i_op ||
783 !subdir->d_inode->i_op->setxattr ||
784 !subdir->d_inode->i_op->getxattr ||
785 !subdir->d_inode->i_op->lookup ||
786 !subdir->d_inode->i_op->mkdir ||
787 !subdir->d_inode->i_op->create ||
788 !subdir->d_inode->i_op->rename ||
789 !subdir->d_inode->i_op->rmdir ||
790 !subdir->d_inode->i_op->unlink)
791 goto check_error;
792
793 _leave(" = [%lu]", subdir->d_inode->i_ino);
794 return subdir;
795
796 check_error:
797 dput(subdir);
798 _leave(" = %d [check]", ret);
799 return ERR_PTR(ret);
800
801 mkdir_error:
802 mutex_unlock(&dir->d_inode->i_mutex);
803 dput(subdir);
804 kerror("mkdir %s failed with error %d", dirname, ret);
805 return ERR_PTR(ret);
806
807 lookup_error:
808 mutex_unlock(&dir->d_inode->i_mutex);
809 ret = PTR_ERR(subdir);
810 kerror("Lookup %s failed with error %d", dirname, ret);
811 return ERR_PTR(ret);
812
813 nomem_d_alloc:
814 mutex_unlock(&dir->d_inode->i_mutex);
815 _leave(" = -ENOMEM");
816 return ERR_PTR(-ENOMEM);
817 }
818
819 /*
820 * find out if an object is in use or not
821 * - if finds object and it's not in use:
822 * - returns a pointer to the object and a reference on it
823 * - returns with the directory locked
824 */
cachefiles_check_active(struct cachefiles_cache * cache,struct dentry * dir,char * filename)825 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
826 struct dentry *dir,
827 char *filename)
828 {
829 struct cachefiles_object *object;
830 struct rb_node *_n;
831 struct dentry *victim;
832 unsigned long start;
833 int ret;
834
835 //_enter(",%*.*s/,%s",
836 // dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
837
838 /* look up the victim */
839 mutex_lock_nested(&dir->d_inode->i_mutex, 1);
840
841 start = jiffies;
842 victim = lookup_one_len(filename, dir, strlen(filename));
843 cachefiles_hist(cachefiles_lookup_histogram, start);
844 if (IS_ERR(victim))
845 goto lookup_error;
846
847 //_debug("victim -> %p %s",
848 // victim, victim->d_inode ? "positive" : "negative");
849
850 /* if the object is no longer there then we probably retired the object
851 * at the netfs's request whilst the cull was in progress
852 */
853 if (!victim->d_inode) {
854 mutex_unlock(&dir->d_inode->i_mutex);
855 dput(victim);
856 _leave(" = -ENOENT [absent]");
857 return ERR_PTR(-ENOENT);
858 }
859
860 /* check to see if we're using this object */
861 read_lock(&cache->active_lock);
862
863 _n = cache->active_nodes.rb_node;
864
865 while (_n) {
866 object = rb_entry(_n, struct cachefiles_object, active_node);
867
868 if (object->dentry > victim)
869 _n = _n->rb_left;
870 else if (object->dentry < victim)
871 _n = _n->rb_right;
872 else
873 goto object_in_use;
874 }
875
876 read_unlock(&cache->active_lock);
877
878 //_leave(" = %p", victim);
879 return victim;
880
881 object_in_use:
882 read_unlock(&cache->active_lock);
883 mutex_unlock(&dir->d_inode->i_mutex);
884 dput(victim);
885 //_leave(" = -EBUSY [in use]");
886 return ERR_PTR(-EBUSY);
887
888 lookup_error:
889 mutex_unlock(&dir->d_inode->i_mutex);
890 ret = PTR_ERR(victim);
891 if (ret == -ENOENT) {
892 /* file or dir now absent - probably retired by netfs */
893 _leave(" = -ESTALE [absent]");
894 return ERR_PTR(-ESTALE);
895 }
896
897 if (ret == -EIO) {
898 cachefiles_io_error(cache, "Lookup failed");
899 } else if (ret != -ENOMEM) {
900 kerror("Internal error: %d", ret);
901 ret = -EIO;
902 }
903
904 _leave(" = %d", ret);
905 return ERR_PTR(ret);
906 }
907
908 /*
909 * cull an object if it's not in use
910 * - called only by cache manager daemon
911 */
cachefiles_cull(struct cachefiles_cache * cache,struct dentry * dir,char * filename)912 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
913 char *filename)
914 {
915 struct dentry *victim;
916 int ret;
917
918 _enter(",%*.*s/,%s",
919 dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
920
921 victim = cachefiles_check_active(cache, dir, filename);
922 if (IS_ERR(victim))
923 return PTR_ERR(victim);
924
925 _debug("victim -> %p %s",
926 victim, victim->d_inode ? "positive" : "negative");
927
928 /* okay... the victim is not being used so we can cull it
929 * - start by marking it as stale
930 */
931 _debug("victim is cullable");
932
933 ret = cachefiles_remove_object_xattr(cache, victim);
934 if (ret < 0)
935 goto error_unlock;
936
937 /* actually remove the victim (drops the dir mutex) */
938 _debug("bury");
939
940 ret = cachefiles_bury_object(cache, dir, victim, false);
941 if (ret < 0)
942 goto error;
943
944 dput(victim);
945 _leave(" = 0");
946 return 0;
947
948 error_unlock:
949 mutex_unlock(&dir->d_inode->i_mutex);
950 error:
951 dput(victim);
952 if (ret == -ENOENT) {
953 /* file or dir now absent - probably retired by netfs */
954 _leave(" = -ESTALE [absent]");
955 return -ESTALE;
956 }
957
958 if (ret != -ENOMEM) {
959 kerror("Internal error: %d", ret);
960 ret = -EIO;
961 }
962
963 _leave(" = %d", ret);
964 return ret;
965 }
966
967 /*
968 * find out if an object is in use or not
969 * - called only by cache manager daemon
970 * - returns -EBUSY or 0 to indicate whether an object is in use or not
971 */
cachefiles_check_in_use(struct cachefiles_cache * cache,struct dentry * dir,char * filename)972 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
973 char *filename)
974 {
975 struct dentry *victim;
976
977 //_enter(",%*.*s/,%s",
978 // dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
979
980 victim = cachefiles_check_active(cache, dir, filename);
981 if (IS_ERR(victim))
982 return PTR_ERR(victim);
983
984 mutex_unlock(&dir->d_inode->i_mutex);
985 dput(victim);
986 //_leave(" = 0");
987 return 0;
988 }
989