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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* CacheFiles path walking and related routines
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/module.h>
9#include <linux/sched.h>
10#include <linux/file.h>
11#include <linux/fs.h>
12#include <linux/fsnotify.h>
13#include <linux/quotaops.h>
14#include <linux/xattr.h>
15#include <linux/mount.h>
16#include <linux/namei.h>
17#include <linux/security.h>
18#include <linux/slab.h>
19#include "internal.h"
20
21#define CACHEFILES_KEYBUF_SIZE 512
22
23/*
24 * dump debugging info about an object
25 */
26static noinline
27void __cachefiles_printk_object(struct cachefiles_object *object,
28 const char *prefix)
29{
30 struct fscache_cookie *cookie;
31 const u8 *k;
32 unsigned loop;
33
34 pr_err("%sobject: OBJ%x\n", prefix, object->fscache.debug_id);
35 pr_err("%sobjstate=%s fl=%lx wbusy=%x ev=%lx[%lx]\n",
36 prefix, object->fscache.state->name,
37 object->fscache.flags, work_busy(&object->fscache.work),
38 object->fscache.events, object->fscache.event_mask);
39 pr_err("%sops=%u inp=%u exc=%u\n",
40 prefix, object->fscache.n_ops, object->fscache.n_in_progress,
41 object->fscache.n_exclusive);
42 pr_err("%sparent=%p\n",
43 prefix, object->fscache.parent);
44
45 spin_lock(&object->fscache.lock);
46 cookie = object->fscache.cookie;
47 if (cookie) {
48 pr_err("%scookie=%p [pr=%p nd=%p fl=%lx]\n",
49 prefix,
50 object->fscache.cookie,
51 object->fscache.cookie->parent,
52 object->fscache.cookie->netfs_data,
53 object->fscache.cookie->flags);
54 pr_err("%skey=[%u] '", prefix, cookie->key_len);
55 k = (cookie->key_len <= sizeof(cookie->inline_key)) ?
56 cookie->inline_key : cookie->key;
57 for (loop = 0; loop < cookie->key_len; loop++)
58 pr_cont("%02x", k[loop]);
59 pr_cont("'\n");
60 } else {
61 pr_err("%scookie=NULL\n", prefix);
62 }
63 spin_unlock(&object->fscache.lock);
64}
65
66/*
67 * dump debugging info about a pair of objects
68 */
69static noinline void cachefiles_printk_object(struct cachefiles_object *object,
70 struct cachefiles_object *xobject)
71{
72 if (object)
73 __cachefiles_printk_object(object, "");
74 if (xobject)
75 __cachefiles_printk_object(xobject, "x");
76}
77
78/*
79 * mark the owner of a dentry, if there is one, to indicate that that dentry
80 * has been preemptively deleted
81 * - the caller must hold the i_mutex on the dentry's parent as required to
82 * call vfs_unlink(), vfs_rmdir() or vfs_rename()
83 */
84static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
85 struct dentry *dentry,
86 enum fscache_why_object_killed why)
87{
88 struct cachefiles_object *object;
89 struct rb_node *p;
90
91 _enter(",'%pd'", dentry);
92
93 write_lock(&cache->active_lock);
94
95 p = cache->active_nodes.rb_node;
96 while (p) {
97 object = rb_entry(p, struct cachefiles_object, active_node);
98 if (object->dentry > dentry)
99 p = p->rb_left;
100 else if (object->dentry < dentry)
101 p = p->rb_right;
102 else
103 goto found_dentry;
104 }
105
106 write_unlock(&cache->active_lock);
107 trace_cachefiles_mark_buried(NULL, dentry, why);
108 _leave(" [no owner]");
109 return;
110
111 /* found the dentry for */
112found_dentry:
113 kdebug("preemptive burial: OBJ%x [%s] %p",
114 object->fscache.debug_id,
115 object->fscache.state->name,
116 dentry);
117
118 trace_cachefiles_mark_buried(object, dentry, why);
119
120 if (fscache_object_is_live(&object->fscache)) {
121 pr_err("\n");
122 pr_err("Error: Can't preemptively bury live object\n");
123 cachefiles_printk_object(object, NULL);
124 } else {
125 if (why != FSCACHE_OBJECT_IS_STALE)
126 fscache_object_mark_killed(&object->fscache, why);
127 }
128
129 write_unlock(&cache->active_lock);
130 _leave(" [owner marked]");
131}
132
133/*
134 * record the fact that an object is now active
135 */
136static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
137 struct cachefiles_object *object)
138{
139 struct cachefiles_object *xobject;
140 struct rb_node **_p, *_parent = NULL;
141 struct dentry *dentry;
142
143 _enter(",%p", object);
144
145try_again:
146 write_lock(&cache->active_lock);
147
148 dentry = object->dentry;
149 trace_cachefiles_mark_active(object, dentry);
150
151 if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
152 pr_err("Error: Object already active\n");
153 cachefiles_printk_object(object, NULL);
154 BUG();
155 }
156
157 _p = &cache->active_nodes.rb_node;
158 while (*_p) {
159 _parent = *_p;
160 xobject = rb_entry(_parent,
161 struct cachefiles_object, active_node);
162
163 ASSERT(xobject != object);
164
165 if (xobject->dentry > dentry)
166 _p = &(*_p)->rb_left;
167 else if (xobject->dentry < dentry)
168 _p = &(*_p)->rb_right;
169 else
170 goto wait_for_old_object;
171 }
172
173 rb_link_node(&object->active_node, _parent, _p);
174 rb_insert_color(&object->active_node, &cache->active_nodes);
175
176 write_unlock(&cache->active_lock);
177 _leave(" = 0");
178 return 0;
179
180 /* an old object from a previous incarnation is hogging the slot - we
181 * need to wait for it to be destroyed */
182wait_for_old_object:
183 trace_cachefiles_wait_active(object, dentry, xobject);
184 clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
185
186 if (fscache_object_is_live(&xobject->fscache)) {
187 pr_err("\n");
188 pr_err("Error: Unexpected object collision\n");
189 cachefiles_printk_object(object, xobject);
190 }
191 atomic_inc(&xobject->usage);
192 write_unlock(&cache->active_lock);
193
194 if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
195 wait_queue_head_t *wq;
196
197 signed long timeout = 60 * HZ;
198 wait_queue_entry_t wait;
199 bool requeue;
200
201 /* if the object we're waiting for is queued for processing,
202 * then just put ourselves on the queue behind it */
203 if (work_pending(&xobject->fscache.work)) {
204 _debug("queue OBJ%x behind OBJ%x immediately",
205 object->fscache.debug_id,
206 xobject->fscache.debug_id);
207 goto requeue;
208 }
209
210 /* otherwise we sleep until either the object we're waiting for
211 * is done, or the fscache_object is congested */
212 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
213 init_wait(&wait);
214 requeue = false;
215 do {
216 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
217 if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
218 break;
219
220 requeue = fscache_object_sleep_till_congested(&timeout);
221 } while (timeout > 0 && !requeue);
222 finish_wait(wq, &wait);
223
224 if (requeue &&
225 test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
226 _debug("queue OBJ%x behind OBJ%x after wait",
227 object->fscache.debug_id,
228 xobject->fscache.debug_id);
229 goto requeue;
230 }
231
232 if (timeout <= 0) {
233 pr_err("\n");
234 pr_err("Error: Overlong wait for old active object to go away\n");
235 cachefiles_printk_object(object, xobject);
236 goto requeue;
237 }
238 }
239
240 ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
241
242 cache->cache.ops->put_object(&xobject->fscache,
243 (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_retry);
244 goto try_again;
245
246requeue:
247 cache->cache.ops->put_object(&xobject->fscache,
248 (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_timeo);
249 _leave(" = -ETIMEDOUT");
250 return -ETIMEDOUT;
251}
252
253/*
254 * Mark an object as being inactive.
255 */
256void cachefiles_mark_object_inactive(struct cachefiles_cache *cache,
257 struct cachefiles_object *object,
258 blkcnt_t i_blocks)
259{
260 struct dentry *dentry = object->dentry;
261 struct inode *inode = d_backing_inode(dentry);
262
263 trace_cachefiles_mark_inactive(object, dentry, inode);
264
265 write_lock(&cache->active_lock);
266 rb_erase(&object->active_node, &cache->active_nodes);
267 clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
268 write_unlock(&cache->active_lock);
269
270 wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
271
272 /* This object can now be culled, so we need to let the daemon know
273 * that there is something it can remove if it needs to.
274 */
275 atomic_long_add(i_blocks, &cache->b_released);
276 if (atomic_inc_return(&cache->f_released))
277 cachefiles_state_changed(cache);
278}
279
280/*
281 * delete an object representation from the cache
282 * - file backed objects are unlinked
283 * - directory backed objects are stuffed into the graveyard for userspace to
284 * delete
285 * - unlocks the directory mutex
286 */
287static int cachefiles_bury_object(struct cachefiles_cache *cache,
288 struct cachefiles_object *object,
289 struct dentry *dir,
290 struct dentry *rep,
291 bool preemptive,
292 enum fscache_why_object_killed why)
293{
294 struct dentry *grave, *trap;
295 struct path path, path_to_graveyard;
296 char nbuffer[8 + 8 + 1];
297 int ret;
298
299 _enter(",'%pd','%pd'", dir, rep);
300
301 _debug("remove %p from %p", rep, dir);
302
303 /* non-directories can just be unlinked */
304 if (!d_is_dir(rep)) {
305 _debug("unlink stale object");
306
307 path.mnt = cache->mnt;
308 path.dentry = dir;
309 ret = security_path_unlink(&path, rep);
310 if (ret < 0) {
311 cachefiles_io_error(cache, "Unlink security error");
312 } else {
313 trace_cachefiles_unlink(object, rep, why);
314 ret = vfs_unlink(d_inode(dir), rep, NULL);
315
316 if (preemptive)
317 cachefiles_mark_object_buried(cache, rep, why);
318 }
319
320 inode_unlock(d_inode(dir));
321
322 if (ret == -EIO)
323 cachefiles_io_error(cache, "Unlink failed");
324
325 _leave(" = %d", ret);
326 return ret;
327 }
328
329 /* directories have to be moved to the graveyard */
330 _debug("move stale object to graveyard");
331 inode_unlock(d_inode(dir));
332
333try_again:
334 /* first step is to make up a grave dentry in the graveyard */
335 sprintf(nbuffer, "%08x%08x",
336 (uint32_t) ktime_get_real_seconds(),
337 (uint32_t) atomic_inc_return(&cache->gravecounter));
338
339 /* do the multiway lock magic */
340 trap = lock_rename(cache->graveyard, dir);
341
342 /* do some checks before getting the grave dentry */
343 if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) {
344 /* the entry was probably culled when we dropped the parent dir
345 * lock */
346 unlock_rename(cache->graveyard, dir);
347 _leave(" = 0 [culled?]");
348 return 0;
349 }
350
351 if (!d_can_lookup(cache->graveyard)) {
352 unlock_rename(cache->graveyard, dir);
353 cachefiles_io_error(cache, "Graveyard no longer a directory");
354 return -EIO;
355 }
356
357 if (trap == rep) {
358 unlock_rename(cache->graveyard, dir);
359 cachefiles_io_error(cache, "May not make directory loop");
360 return -EIO;
361 }
362
363 if (d_mountpoint(rep)) {
364 unlock_rename(cache->graveyard, dir);
365 cachefiles_io_error(cache, "Mountpoint in cache");
366 return -EIO;
367 }
368
369 grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
370 if (IS_ERR(grave)) {
371 unlock_rename(cache->graveyard, dir);
372
373 if (PTR_ERR(grave) == -ENOMEM) {
374 _leave(" = -ENOMEM");
375 return -ENOMEM;
376 }
377
378 cachefiles_io_error(cache, "Lookup error %ld",
379 PTR_ERR(grave));
380 return -EIO;
381 }
382
383 if (d_is_positive(grave)) {
384 unlock_rename(cache->graveyard, dir);
385 dput(grave);
386 grave = NULL;
387 cond_resched();
388 goto try_again;
389 }
390
391 if (d_mountpoint(grave)) {
392 unlock_rename(cache->graveyard, dir);
393 dput(grave);
394 cachefiles_io_error(cache, "Mountpoint in graveyard");
395 return -EIO;
396 }
397
398 /* target should not be an ancestor of source */
399 if (trap == grave) {
400 unlock_rename(cache->graveyard, dir);
401 dput(grave);
402 cachefiles_io_error(cache, "May not make directory loop");
403 return -EIO;
404 }
405
406 /* attempt the rename */
407 path.mnt = cache->mnt;
408 path.dentry = dir;
409 path_to_graveyard.mnt = cache->mnt;
410 path_to_graveyard.dentry = cache->graveyard;
411 ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0);
412 if (ret < 0) {
413 cachefiles_io_error(cache, "Rename security error %d", ret);
414 } else {
415 trace_cachefiles_rename(object, rep, grave, why);
416 ret = vfs_rename(d_inode(dir), rep,
417 d_inode(cache->graveyard), grave, NULL, 0);
418 if (ret != 0 && ret != -ENOMEM)
419 cachefiles_io_error(cache,
420 "Rename failed with error %d", ret);
421
422 if (preemptive)
423 cachefiles_mark_object_buried(cache, rep, why);
424 }
425
426 unlock_rename(cache->graveyard, dir);
427 dput(grave);
428 _leave(" = 0");
429 return 0;
430}
431
432/*
433 * delete an object representation from the cache
434 */
435int cachefiles_delete_object(struct cachefiles_cache *cache,
436 struct cachefiles_object *object)
437{
438 struct dentry *dir;
439 int ret;
440
441 _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
442
443 ASSERT(object->dentry);
444 ASSERT(d_backing_inode(object->dentry));
445 ASSERT(object->dentry->d_parent);
446
447 dir = dget_parent(object->dentry);
448
449 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
450
451 if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
452 /* object allocation for the same key preemptively deleted this
453 * object's file so that it could create its own file */
454 _debug("object preemptively buried");
455 inode_unlock(d_inode(dir));
456 ret = 0;
457 } else {
458 /* we need to check that our parent is _still_ our parent - it
459 * may have been renamed */
460 if (dir == object->dentry->d_parent) {
461 ret = cachefiles_bury_object(cache, object, dir,
462 object->dentry, false,
463 FSCACHE_OBJECT_WAS_RETIRED);
464 } else {
465 /* it got moved, presumably by cachefilesd culling it,
466 * so it's no longer in the key path and we can ignore
467 * it */
468 inode_unlock(d_inode(dir));
469 ret = 0;
470 }
471 }
472
473 dput(dir);
474 _leave(" = %d", ret);
475 return ret;
476}
477
478/*
479 * walk from the parent object to the child object through the backing
480 * filesystem, creating directories as we go
481 */
482int cachefiles_walk_to_object(struct cachefiles_object *parent,
483 struct cachefiles_object *object,
484 const char *key,
485 struct cachefiles_xattr *auxdata)
486{
487 struct cachefiles_cache *cache;
488 struct dentry *dir, *next = NULL;
489 struct inode *inode;
490 struct path path;
491 unsigned long start;
492 const char *name;
493 int ret, nlen;
494
495 _enter("OBJ%x{%p},OBJ%x,%s,",
496 parent->fscache.debug_id, parent->dentry,
497 object->fscache.debug_id, key);
498
499 cache = container_of(parent->fscache.cache,
500 struct cachefiles_cache, cache);
501 path.mnt = cache->mnt;
502
503 ASSERT(parent->dentry);
504 ASSERT(d_backing_inode(parent->dentry));
505
506 if (!(d_is_dir(parent->dentry))) {
507 // TODO: convert file to dir
508 _leave("looking up in none directory");
509 return -ENOBUFS;
510 }
511
512 dir = dget(parent->dentry);
513
514advance:
515 /* attempt to transit the first directory component */
516 name = key;
517 nlen = strlen(key);
518
519 /* key ends in a double NUL */
520 key = key + nlen + 1;
521 if (!*key)
522 key = NULL;
523
524lookup_again:
525 /* search the current directory for the element name */
526 _debug("lookup '%s'", name);
527
528 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
529
530 start = jiffies;
531 next = lookup_one_len(name, dir, nlen);
532 cachefiles_hist(cachefiles_lookup_histogram, start);
533 if (IS_ERR(next)) {
534 trace_cachefiles_lookup(object, next, NULL);
535 goto lookup_error;
536 }
537
538 inode = d_backing_inode(next);
539 trace_cachefiles_lookup(object, next, inode);
540 _debug("next -> %p %s", next, inode ? "positive" : "negative");
541
542 if (!key)
543 object->new = !inode;
544
545 /* if this element of the path doesn't exist, then the lookup phase
546 * failed, and we can release any readers in the certain knowledge that
547 * there's nothing for them to actually read */
548 if (d_is_negative(next))
549 fscache_object_lookup_negative(&object->fscache);
550
551 /* we need to create the object if it's negative */
552 if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
553 /* index objects and intervening tree levels must be subdirs */
554 if (d_is_negative(next)) {
555 ret = cachefiles_has_space(cache, 1, 0);
556 if (ret < 0)
557 goto no_space_error;
558
559 path.dentry = dir;
560 ret = security_path_mkdir(&path, next, 0);
561 if (ret < 0)
562 goto create_error;
563 start = jiffies;
564 ret = vfs_mkdir(d_inode(dir), next, 0);
565 cachefiles_hist(cachefiles_mkdir_histogram, start);
566 if (!key)
567 trace_cachefiles_mkdir(object, next, ret);
568 if (ret < 0)
569 goto create_error;
570
571 if (unlikely(d_unhashed(next))) {
572 dput(next);
573 inode_unlock(d_inode(dir));
574 goto lookup_again;
575 }
576 ASSERT(d_backing_inode(next));
577
578 _debug("mkdir -> %p{%p{ino=%lu}}",
579 next, d_backing_inode(next), d_backing_inode(next)->i_ino);
580
581 } else if (!d_can_lookup(next)) {
582 pr_err("inode %lu is not a directory\n",
583 d_backing_inode(next)->i_ino);
584 ret = -ENOBUFS;
585 goto error;
586 }
587
588 } else {
589 /* non-index objects start out life as files */
590 if (d_is_negative(next)) {
591 ret = cachefiles_has_space(cache, 1, 0);
592 if (ret < 0)
593 goto no_space_error;
594
595 path.dentry = dir;
596 ret = security_path_mknod(&path, next, S_IFREG, 0);
597 if (ret < 0)
598 goto create_error;
599 start = jiffies;
600 ret = vfs_create(d_inode(dir), next, S_IFREG, true);
601 cachefiles_hist(cachefiles_create_histogram, start);
602 trace_cachefiles_create(object, next, ret);
603 if (ret < 0)
604 goto create_error;
605
606 ASSERT(d_backing_inode(next));
607
608 _debug("create -> %p{%p{ino=%lu}}",
609 next, d_backing_inode(next), d_backing_inode(next)->i_ino);
610
611 } else if (!d_can_lookup(next) &&
612 !d_is_reg(next)
613 ) {
614 pr_err("inode %lu is not a file or directory\n",
615 d_backing_inode(next)->i_ino);
616 ret = -ENOBUFS;
617 goto error;
618 }
619 }
620
621 /* process the next component */
622 if (key) {
623 _debug("advance");
624 inode_unlock(d_inode(dir));
625 dput(dir);
626 dir = next;
627 next = NULL;
628 goto advance;
629 }
630
631 /* we've found the object we were looking for */
632 object->dentry = next;
633
634 /* if we've found that the terminal object exists, then we need to
635 * check its attributes and delete it if it's out of date */
636 if (!object->new) {
637 _debug("validate '%pd'", next);
638
639 ret = cachefiles_check_object_xattr(object, auxdata);
640 if (ret == -ESTALE) {
641 /* delete the object (the deleter drops the directory
642 * mutex) */
643 object->dentry = NULL;
644
645 ret = cachefiles_bury_object(cache, object, dir, next,
646 true,
647 FSCACHE_OBJECT_IS_STALE);
648 dput(next);
649 next = NULL;
650
651 if (ret < 0)
652 goto delete_error;
653
654 _debug("redo lookup");
655 fscache_object_retrying_stale(&object->fscache);
656 goto lookup_again;
657 }
658 }
659
660 /* note that we're now using this object */
661 ret = cachefiles_mark_object_active(cache, object);
662
663 inode_unlock(d_inode(dir));
664 dput(dir);
665 dir = NULL;
666
667 if (ret == -ETIMEDOUT)
668 goto mark_active_timed_out;
669
670 _debug("=== OBTAINED_OBJECT ===");
671
672 if (object->new) {
673 /* attach data to a newly constructed terminal object */
674 ret = cachefiles_set_object_xattr(object, auxdata);
675 if (ret < 0)
676 goto check_error;
677 } else {
678 /* always update the atime on an object we've just looked up
679 * (this is used to keep track of culling, and atimes are only
680 * updated by read, write and readdir but not lookup or
681 * open) */
682 path.dentry = next;
683 touch_atime(&path);
684 }
685
686 /* open a file interface onto a data file */
687 if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
688 if (d_is_reg(object->dentry)) {
689 const struct address_space_operations *aops;
690
691 ret = -EPERM;
692 aops = d_backing_inode(object->dentry)->i_mapping->a_ops;
693 if (!aops->bmap)
694 goto check_error;
695 if (object->dentry->d_sb->s_blocksize > PAGE_SIZE)
696 goto check_error;
697
698 object->backer = object->dentry;
699 } else {
700 BUG(); // TODO: open file in data-class subdir
701 }
702 }
703
704 object->new = 0;
705 fscache_obtained_object(&object->fscache);
706
707 _leave(" = 0 [%lu]", d_backing_inode(object->dentry)->i_ino);
708 return 0;
709
710no_space_error:
711 fscache_object_mark_killed(&object->fscache, FSCACHE_OBJECT_NO_SPACE);
712create_error:
713 _debug("create error %d", ret);
714 if (ret == -EIO)
715 cachefiles_io_error(cache, "Create/mkdir failed");
716 goto error;
717
718mark_active_timed_out:
719 _debug("mark active timed out");
720 goto release_dentry;
721
722check_error:
723 _debug("check error %d", ret);
724 cachefiles_mark_object_inactive(
725 cache, object, d_backing_inode(object->dentry)->i_blocks);
726release_dentry:
727 dput(object->dentry);
728 object->dentry = NULL;
729 goto error_out;
730
731delete_error:
732 _debug("delete error %d", ret);
733 goto error_out2;
734
735lookup_error:
736 _debug("lookup error %ld", PTR_ERR(next));
737 ret = PTR_ERR(next);
738 if (ret == -EIO)
739 cachefiles_io_error(cache, "Lookup failed");
740 next = NULL;
741error:
742 inode_unlock(d_inode(dir));
743 dput(next);
744error_out2:
745 dput(dir);
746error_out:
747 _leave(" = error %d", -ret);
748 return ret;
749}
750
751/*
752 * get a subdirectory
753 */
754struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
755 struct dentry *dir,
756 const char *dirname)
757{
758 struct dentry *subdir;
759 unsigned long start;
760 struct path path;
761 int ret;
762
763 _enter(",,%s", dirname);
764
765 /* search the current directory for the element name */
766 inode_lock(d_inode(dir));
767
768retry:
769 start = jiffies;
770 subdir = lookup_one_len(dirname, dir, strlen(dirname));
771 cachefiles_hist(cachefiles_lookup_histogram, start);
772 if (IS_ERR(subdir)) {
773 if (PTR_ERR(subdir) == -ENOMEM)
774 goto nomem_d_alloc;
775 goto lookup_error;
776 }
777
778 _debug("subdir -> %p %s",
779 subdir, d_backing_inode(subdir) ? "positive" : "negative");
780
781 /* we need to create the subdir if it doesn't exist yet */
782 if (d_is_negative(subdir)) {
783 ret = cachefiles_has_space(cache, 1, 0);
784 if (ret < 0)
785 goto mkdir_error;
786
787 _debug("attempt mkdir");
788
789 path.mnt = cache->mnt;
790 path.dentry = dir;
791 ret = security_path_mkdir(&path, subdir, 0700);
792 if (ret < 0)
793 goto mkdir_error;
794 ret = vfs_mkdir(d_inode(dir), subdir, 0700);
795 if (ret < 0)
796 goto mkdir_error;
797
798 if (unlikely(d_unhashed(subdir))) {
799 dput(subdir);
800 goto retry;
801 }
802 ASSERT(d_backing_inode(subdir));
803
804 _debug("mkdir -> %p{%p{ino=%lu}}",
805 subdir,
806 d_backing_inode(subdir),
807 d_backing_inode(subdir)->i_ino);
808 }
809
810 inode_unlock(d_inode(dir));
811
812 /* we need to make sure the subdir is a directory */
813 ASSERT(d_backing_inode(subdir));
814
815 if (!d_can_lookup(subdir)) {
816 pr_err("%s is not a directory\n", dirname);
817 ret = -EIO;
818 goto check_error;
819 }
820
821 ret = -EPERM;
822 if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) ||
823 !d_backing_inode(subdir)->i_op->lookup ||
824 !d_backing_inode(subdir)->i_op->mkdir ||
825 !d_backing_inode(subdir)->i_op->create ||
826 !d_backing_inode(subdir)->i_op->rename ||
827 !d_backing_inode(subdir)->i_op->rmdir ||
828 !d_backing_inode(subdir)->i_op->unlink)
829 goto check_error;
830
831 _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
832 return subdir;
833
834check_error:
835 dput(subdir);
836 _leave(" = %d [check]", ret);
837 return ERR_PTR(ret);
838
839mkdir_error:
840 inode_unlock(d_inode(dir));
841 dput(subdir);
842 pr_err("mkdir %s failed with error %d\n", dirname, ret);
843 return ERR_PTR(ret);
844
845lookup_error:
846 inode_unlock(d_inode(dir));
847 ret = PTR_ERR(subdir);
848 pr_err("Lookup %s failed with error %d\n", dirname, ret);
849 return ERR_PTR(ret);
850
851nomem_d_alloc:
852 inode_unlock(d_inode(dir));
853 _leave(" = -ENOMEM");
854 return ERR_PTR(-ENOMEM);
855}
856
857/*
858 * find out if an object is in use or not
859 * - if finds object and it's not in use:
860 * - returns a pointer to the object and a reference on it
861 * - returns with the directory locked
862 */
863static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
864 struct dentry *dir,
865 char *filename)
866{
867 struct cachefiles_object *object;
868 struct rb_node *_n;
869 struct dentry *victim;
870 unsigned long start;
871 int ret;
872
873 //_enter(",%pd/,%s",
874 // dir, filename);
875
876 /* look up the victim */
877 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
878
879 start = jiffies;
880 victim = lookup_one_len(filename, dir, strlen(filename));
881 cachefiles_hist(cachefiles_lookup_histogram, start);
882 if (IS_ERR(victim))
883 goto lookup_error;
884
885 //_debug("victim -> %p %s",
886 // victim, d_backing_inode(victim) ? "positive" : "negative");
887
888 /* if the object is no longer there then we probably retired the object
889 * at the netfs's request whilst the cull was in progress
890 */
891 if (d_is_negative(victim)) {
892 inode_unlock(d_inode(dir));
893 dput(victim);
894 _leave(" = -ENOENT [absent]");
895 return ERR_PTR(-ENOENT);
896 }
897
898 /* check to see if we're using this object */
899 read_lock(&cache->active_lock);
900
901 _n = cache->active_nodes.rb_node;
902
903 while (_n) {
904 object = rb_entry(_n, struct cachefiles_object, active_node);
905
906 if (object->dentry > victim)
907 _n = _n->rb_left;
908 else if (object->dentry < victim)
909 _n = _n->rb_right;
910 else
911 goto object_in_use;
912 }
913
914 read_unlock(&cache->active_lock);
915
916 //_leave(" = %p", victim);
917 return victim;
918
919object_in_use:
920 read_unlock(&cache->active_lock);
921 inode_unlock(d_inode(dir));
922 dput(victim);
923 //_leave(" = -EBUSY [in use]");
924 return ERR_PTR(-EBUSY);
925
926lookup_error:
927 inode_unlock(d_inode(dir));
928 ret = PTR_ERR(victim);
929 if (ret == -ENOENT) {
930 /* file or dir now absent - probably retired by netfs */
931 _leave(" = -ESTALE [absent]");
932 return ERR_PTR(-ESTALE);
933 }
934
935 if (ret == -EIO) {
936 cachefiles_io_error(cache, "Lookup failed");
937 } else if (ret != -ENOMEM) {
938 pr_err("Internal error: %d\n", ret);
939 ret = -EIO;
940 }
941
942 _leave(" = %d", ret);
943 return ERR_PTR(ret);
944}
945
946/*
947 * cull an object if it's not in use
948 * - called only by cache manager daemon
949 */
950int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
951 char *filename)
952{
953 struct dentry *victim;
954 int ret;
955
956 _enter(",%pd/,%s", dir, filename);
957
958 victim = cachefiles_check_active(cache, dir, filename);
959 if (IS_ERR(victim))
960 return PTR_ERR(victim);
961
962 _debug("victim -> %p %s",
963 victim, d_backing_inode(victim) ? "positive" : "negative");
964
965 /* okay... the victim is not being used so we can cull it
966 * - start by marking it as stale
967 */
968 _debug("victim is cullable");
969
970 ret = cachefiles_remove_object_xattr(cache, victim);
971 if (ret < 0)
972 goto error_unlock;
973
974 /* actually remove the victim (drops the dir mutex) */
975 _debug("bury");
976
977 ret = cachefiles_bury_object(cache, NULL, dir, victim, false,
978 FSCACHE_OBJECT_WAS_CULLED);
979 if (ret < 0)
980 goto error;
981
982 dput(victim);
983 _leave(" = 0");
984 return 0;
985
986error_unlock:
987 inode_unlock(d_inode(dir));
988error:
989 dput(victim);
990 if (ret == -ENOENT) {
991 /* file or dir now absent - probably retired by netfs */
992 _leave(" = -ESTALE [absent]");
993 return -ESTALE;
994 }
995
996 if (ret != -ENOMEM) {
997 pr_err("Internal error: %d\n", ret);
998 ret = -EIO;
999 }
1000
1001 _leave(" = %d", ret);
1002 return ret;
1003}
1004
1005/*
1006 * find out if an object is in use or not
1007 * - called only by cache manager daemon
1008 * - returns -EBUSY or 0 to indicate whether an object is in use or not
1009 */
1010int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
1011 char *filename)
1012{
1013 struct dentry *victim;
1014
1015 //_enter(",%pd/,%s",
1016 // dir, filename);
1017
1018 victim = cachefiles_check_active(cache, dir, filename);
1019 if (IS_ERR(victim))
1020 return PTR_ERR(victim);
1021
1022 inode_unlock(d_inode(dir));
1023 dput(victim);
1024 //_leave(" = 0");
1025 return 0;
1026}
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 */
30static noinline
31void __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 */
82static 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 */
101static 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 */
128found_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 */
151static 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
160try_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 */
195wait_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
258requeue:
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 */
272static 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
317try_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 */
418int 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 */
464int 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
495advance:
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
505lookup_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
674create_error:
675 _debug("create error %d", ret);
676 if (ret == -EIO)
677 cachefiles_io_error(cache, "Create/mkdir failed");
678 goto error;
679
680mark_active_timed_out:
681 _debug("mark active timed out");
682 goto release_dentry;
683
684check_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);
691release_dentry:
692 dput(object->dentry);
693 object->dentry = NULL;
694 goto error_out;
695
696delete_error:
697 _debug("delete error %d", ret);
698 goto error_out2;
699
700lookup_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;
706error:
707 mutex_unlock(&dir->d_inode->i_mutex);
708 dput(next);
709error_out2:
710 dput(dir);
711error_out:
712 _leave(" = error %d", -ret);
713 return ret;
714}
715
716/*
717 * get a subdirectory
718 */
719struct 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
796check_error:
797 dput(subdir);
798 _leave(" = %d [check]", ret);
799 return ERR_PTR(ret);
800
801mkdir_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
807lookup_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
813nomem_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 */
825static 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
881object_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
888lookup_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 */
912int 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
948error_unlock:
949 mutex_unlock(&dir->d_inode->i_mutex);
950error:
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 */
972int 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}