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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 pr_err("%sobject: OBJ%x\n", prefix, object->fscache.debug_id);
39 pr_err("%sobjstate=%s fl=%lx wbusy=%x ev=%lx[%lx]\n",
40 prefix, object->fscache.state->name,
41 object->fscache.flags, work_busy(&object->fscache.work),
42 object->fscache.events, object->fscache.event_mask);
43 pr_err("%sops=%u inp=%u exc=%u\n",
44 prefix, object->fscache.n_ops, object->fscache.n_in_progress,
45 object->fscache.n_exclusive);
46 pr_err("%sparent=%p\n",
47 prefix, object->fscache.parent);
48
49 spin_lock(&object->fscache.lock);
50 cookie = object->fscache.cookie;
51 if (cookie) {
52 pr_err("%scookie=%p [pr=%p nd=%p fl=%lx]\n",
53 prefix,
54 object->fscache.cookie,
55 object->fscache.cookie->parent,
56 object->fscache.cookie->netfs_data,
57 object->fscache.cookie->flags);
58 if (keybuf && cookie->def)
59 keylen = cookie->def->get_key(cookie->netfs_data, keybuf,
60 CACHEFILES_KEYBUF_SIZE);
61 else
62 keylen = 0;
63 } else {
64 pr_err("%scookie=NULL\n", prefix);
65 keylen = 0;
66 }
67 spin_unlock(&object->fscache.lock);
68
69 if (keylen) {
70 pr_err("%skey=[%u] '", prefix, keylen);
71 for (loop = 0; loop < keylen; loop++)
72 pr_cont("%02x", keybuf[loop]);
73 pr_cont("'\n");
74 }
75}
76
77/*
78 * dump debugging info about a pair of objects
79 */
80static noinline void cachefiles_printk_object(struct cachefiles_object *object,
81 struct cachefiles_object *xobject)
82{
83 u8 *keybuf;
84
85 keybuf = kmalloc(CACHEFILES_KEYBUF_SIZE, GFP_NOIO);
86 if (object)
87 __cachefiles_printk_object(object, "", keybuf);
88 if (xobject)
89 __cachefiles_printk_object(xobject, "x", keybuf);
90 kfree(keybuf);
91}
92
93/*
94 * mark the owner of a dentry, if there is one, to indicate that that dentry
95 * has been preemptively deleted
96 * - the caller must hold the i_mutex on the dentry's parent as required to
97 * call vfs_unlink(), vfs_rmdir() or vfs_rename()
98 */
99static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
100 struct dentry *dentry,
101 enum fscache_why_object_killed why)
102{
103 struct cachefiles_object *object;
104 struct rb_node *p;
105
106 _enter(",'%pd'", dentry);
107
108 write_lock(&cache->active_lock);
109
110 p = cache->active_nodes.rb_node;
111 while (p) {
112 object = rb_entry(p, struct cachefiles_object, active_node);
113 if (object->dentry > dentry)
114 p = p->rb_left;
115 else if (object->dentry < dentry)
116 p = p->rb_right;
117 else
118 goto found_dentry;
119 }
120
121 write_unlock(&cache->active_lock);
122 _leave(" [no owner]");
123 return;
124
125 /* found the dentry for */
126found_dentry:
127 kdebug("preemptive burial: OBJ%x [%s] %p",
128 object->fscache.debug_id,
129 object->fscache.state->name,
130 dentry);
131
132 if (fscache_object_is_live(&object->fscache)) {
133 pr_err("\n");
134 pr_err("Error: Can't preemptively bury live object\n");
135 cachefiles_printk_object(object, NULL);
136 } else {
137 if (why != FSCACHE_OBJECT_IS_STALE)
138 fscache_object_mark_killed(&object->fscache, why);
139 }
140
141 write_unlock(&cache->active_lock);
142 _leave(" [owner marked]");
143}
144
145/*
146 * record the fact that an object is now active
147 */
148static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
149 struct cachefiles_object *object)
150{
151 struct cachefiles_object *xobject;
152 struct rb_node **_p, *_parent = NULL;
153 struct dentry *dentry;
154
155 _enter(",%p", object);
156
157try_again:
158 write_lock(&cache->active_lock);
159
160 if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
161 pr_err("Error: Object already active\n");
162 cachefiles_printk_object(object, NULL);
163 BUG();
164 }
165
166 dentry = object->dentry;
167 _p = &cache->active_nodes.rb_node;
168 while (*_p) {
169 _parent = *_p;
170 xobject = rb_entry(_parent,
171 struct cachefiles_object, active_node);
172
173 ASSERT(xobject != object);
174
175 if (xobject->dentry > dentry)
176 _p = &(*_p)->rb_left;
177 else if (xobject->dentry < dentry)
178 _p = &(*_p)->rb_right;
179 else
180 goto wait_for_old_object;
181 }
182
183 rb_link_node(&object->active_node, _parent, _p);
184 rb_insert_color(&object->active_node, &cache->active_nodes);
185
186 write_unlock(&cache->active_lock);
187 _leave(" = 0");
188 return 0;
189
190 /* an old object from a previous incarnation is hogging the slot - we
191 * need to wait for it to be destroyed */
192wait_for_old_object:
193 if (fscache_object_is_live(&xobject->fscache)) {
194 pr_err("\n");
195 pr_err("Error: Unexpected object collision\n");
196 cachefiles_printk_object(object, xobject);
197 BUG();
198 }
199 atomic_inc(&xobject->usage);
200 write_unlock(&cache->active_lock);
201
202 if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
203 wait_queue_head_t *wq;
204
205 signed long timeout = 60 * HZ;
206 wait_queue_t wait;
207 bool requeue;
208
209 /* if the object we're waiting for is queued for processing,
210 * then just put ourselves on the queue behind it */
211 if (work_pending(&xobject->fscache.work)) {
212 _debug("queue OBJ%x behind OBJ%x immediately",
213 object->fscache.debug_id,
214 xobject->fscache.debug_id);
215 goto requeue;
216 }
217
218 /* otherwise we sleep until either the object we're waiting for
219 * is done, or the fscache_object is congested */
220 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
221 init_wait(&wait);
222 requeue = false;
223 do {
224 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
225 if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
226 break;
227
228 requeue = fscache_object_sleep_till_congested(&timeout);
229 } while (timeout > 0 && !requeue);
230 finish_wait(wq, &wait);
231
232 if (requeue &&
233 test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
234 _debug("queue OBJ%x behind OBJ%x after wait",
235 object->fscache.debug_id,
236 xobject->fscache.debug_id);
237 goto requeue;
238 }
239
240 if (timeout <= 0) {
241 pr_err("\n");
242 pr_err("Error: Overlong wait for old active object to go away\n");
243 cachefiles_printk_object(object, xobject);
244 goto requeue;
245 }
246 }
247
248 ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
249
250 cache->cache.ops->put_object(&xobject->fscache);
251 goto try_again;
252
253requeue:
254 clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
255 cache->cache.ops->put_object(&xobject->fscache);
256 _leave(" = -ETIMEDOUT");
257 return -ETIMEDOUT;
258}
259
260/*
261 * Mark an object as being inactive.
262 */
263void cachefiles_mark_object_inactive(struct cachefiles_cache *cache,
264 struct cachefiles_object *object)
265{
266 write_lock(&cache->active_lock);
267 rb_erase(&object->active_node, &cache->active_nodes);
268 clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
269 write_unlock(&cache->active_lock);
270
271 wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
272
273 /* This object can now be culled, so we need to let the daemon know
274 * that there is something it can remove if it needs to.
275 */
276 atomic_long_add(d_backing_inode(object->dentry)->i_blocks,
277 &cache->b_released);
278 if (atomic_inc_return(&cache->f_released))
279 cachefiles_state_changed(cache);
280}
281
282/*
283 * delete an object representation from the cache
284 * - file backed objects are unlinked
285 * - directory backed objects are stuffed into the graveyard for userspace to
286 * delete
287 * - unlocks the directory mutex
288 */
289static int cachefiles_bury_object(struct cachefiles_cache *cache,
290 struct dentry *dir,
291 struct dentry *rep,
292 bool preemptive,
293 enum fscache_why_object_killed why)
294{
295 struct dentry *grave, *trap;
296 struct path path, path_to_graveyard;
297 char nbuffer[8 + 8 + 1];
298 int ret;
299
300 _enter(",'%pd','%pd'", dir, rep);
301
302 _debug("remove %p from %p", rep, dir);
303
304 /* non-directories can just be unlinked */
305 if (!d_is_dir(rep)) {
306 _debug("unlink stale object");
307
308 path.mnt = cache->mnt;
309 path.dentry = dir;
310 ret = security_path_unlink(&path, rep);
311 if (ret < 0) {
312 cachefiles_io_error(cache, "Unlink security error");
313 } else {
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) get_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) {
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 ret = vfs_rename(d_inode(dir), rep,
416 d_inode(cache->graveyard), grave, NULL, 0);
417 if (ret != 0 && ret != -ENOMEM)
418 cachefiles_io_error(cache,
419 "Rename failed with error %d", ret);
420
421 if (preemptive)
422 cachefiles_mark_object_buried(cache, rep, why);
423 }
424
425 unlock_rename(cache->graveyard, dir);
426 dput(grave);
427 _leave(" = 0");
428 return 0;
429}
430
431/*
432 * delete an object representation from the cache
433 */
434int cachefiles_delete_object(struct cachefiles_cache *cache,
435 struct cachefiles_object *object)
436{
437 struct dentry *dir;
438 int ret;
439
440 _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
441
442 ASSERT(object->dentry);
443 ASSERT(d_backing_inode(object->dentry));
444 ASSERT(object->dentry->d_parent);
445
446 dir = dget_parent(object->dentry);
447
448 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
449
450 if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
451 /* object allocation for the same key preemptively deleted this
452 * object's file so that it could create its own file */
453 _debug("object preemptively buried");
454 inode_unlock(d_inode(dir));
455 ret = 0;
456 } else {
457 /* we need to check that our parent is _still_ our parent - it
458 * may have been renamed */
459 if (dir == object->dentry->d_parent) {
460 ret = cachefiles_bury_object(cache, dir,
461 object->dentry, false,
462 FSCACHE_OBJECT_WAS_RETIRED);
463 } else {
464 /* it got moved, presumably by cachefilesd culling it,
465 * so it's no longer in the key path and we can ignore
466 * it */
467 inode_unlock(d_inode(dir));
468 ret = 0;
469 }
470 }
471
472 dput(dir);
473 _leave(" = %d", ret);
474 return ret;
475}
476
477/*
478 * walk from the parent object to the child object through the backing
479 * filesystem, creating directories as we go
480 */
481int cachefiles_walk_to_object(struct cachefiles_object *parent,
482 struct cachefiles_object *object,
483 const char *key,
484 struct cachefiles_xattr *auxdata)
485{
486 struct cachefiles_cache *cache;
487 struct dentry *dir, *next = NULL;
488 struct path path;
489 unsigned long start;
490 const char *name;
491 int ret, nlen;
492
493 _enter("OBJ%x{%p},OBJ%x,%s,",
494 parent->fscache.debug_id, parent->dentry,
495 object->fscache.debug_id, key);
496
497 cache = container_of(parent->fscache.cache,
498 struct cachefiles_cache, cache);
499 path.mnt = cache->mnt;
500
501 ASSERT(parent->dentry);
502 ASSERT(d_backing_inode(parent->dentry));
503
504 if (!(d_is_dir(parent->dentry))) {
505 // TODO: convert file to dir
506 _leave("looking up in none directory");
507 return -ENOBUFS;
508 }
509
510 dir = dget(parent->dentry);
511
512advance:
513 /* attempt to transit the first directory component */
514 name = key;
515 nlen = strlen(key);
516
517 /* key ends in a double NUL */
518 key = key + nlen + 1;
519 if (!*key)
520 key = NULL;
521
522lookup_again:
523 /* search the current directory for the element name */
524 _debug("lookup '%s'", name);
525
526 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
527
528 start = jiffies;
529 next = lookup_one_len(name, dir, nlen);
530 cachefiles_hist(cachefiles_lookup_histogram, start);
531 if (IS_ERR(next))
532 goto lookup_error;
533
534 _debug("next -> %p %s", next, d_backing_inode(next) ? "positive" : "negative");
535
536 if (!key)
537 object->new = !d_backing_inode(next);
538
539 /* if this element of the path doesn't exist, then the lookup phase
540 * failed, and we can release any readers in the certain knowledge that
541 * there's nothing for them to actually read */
542 if (d_is_negative(next))
543 fscache_object_lookup_negative(&object->fscache);
544
545 /* we need to create the object if it's negative */
546 if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
547 /* index objects and intervening tree levels must be subdirs */
548 if (d_is_negative(next)) {
549 ret = cachefiles_has_space(cache, 1, 0);
550 if (ret < 0)
551 goto no_space_error;
552
553 path.dentry = dir;
554 ret = security_path_mkdir(&path, next, 0);
555 if (ret < 0)
556 goto create_error;
557 start = jiffies;
558 ret = vfs_mkdir(d_inode(dir), next, 0);
559 cachefiles_hist(cachefiles_mkdir_histogram, start);
560 if (ret < 0)
561 goto create_error;
562
563 ASSERT(d_backing_inode(next));
564
565 _debug("mkdir -> %p{%p{ino=%lu}}",
566 next, d_backing_inode(next), d_backing_inode(next)->i_ino);
567
568 } else if (!d_can_lookup(next)) {
569 pr_err("inode %lu is not a directory\n",
570 d_backing_inode(next)->i_ino);
571 ret = -ENOBUFS;
572 goto error;
573 }
574
575 } else {
576 /* non-index objects start out life as files */
577 if (d_is_negative(next)) {
578 ret = cachefiles_has_space(cache, 1, 0);
579 if (ret < 0)
580 goto no_space_error;
581
582 path.dentry = dir;
583 ret = security_path_mknod(&path, next, S_IFREG, 0);
584 if (ret < 0)
585 goto create_error;
586 start = jiffies;
587 ret = vfs_create(d_inode(dir), next, S_IFREG, true);
588 cachefiles_hist(cachefiles_create_histogram, start);
589 if (ret < 0)
590 goto create_error;
591
592 ASSERT(d_backing_inode(next));
593
594 _debug("create -> %p{%p{ino=%lu}}",
595 next, d_backing_inode(next), d_backing_inode(next)->i_ino);
596
597 } else if (!d_can_lookup(next) &&
598 !d_is_reg(next)
599 ) {
600 pr_err("inode %lu is not a file or directory\n",
601 d_backing_inode(next)->i_ino);
602 ret = -ENOBUFS;
603 goto error;
604 }
605 }
606
607 /* process the next component */
608 if (key) {
609 _debug("advance");
610 inode_unlock(d_inode(dir));
611 dput(dir);
612 dir = next;
613 next = NULL;
614 goto advance;
615 }
616
617 /* we've found the object we were looking for */
618 object->dentry = next;
619
620 /* if we've found that the terminal object exists, then we need to
621 * check its attributes and delete it if it's out of date */
622 if (!object->new) {
623 _debug("validate '%pd'", next);
624
625 ret = cachefiles_check_object_xattr(object, auxdata);
626 if (ret == -ESTALE) {
627 /* delete the object (the deleter drops the directory
628 * mutex) */
629 object->dentry = NULL;
630
631 ret = cachefiles_bury_object(cache, dir, next, true,
632 FSCACHE_OBJECT_IS_STALE);
633 dput(next);
634 next = NULL;
635
636 if (ret < 0)
637 goto delete_error;
638
639 _debug("redo lookup");
640 fscache_object_retrying_stale(&object->fscache);
641 goto lookup_again;
642 }
643 }
644
645 /* note that we're now using this object */
646 ret = cachefiles_mark_object_active(cache, object);
647
648 inode_unlock(d_inode(dir));
649 dput(dir);
650 dir = NULL;
651
652 if (ret == -ETIMEDOUT)
653 goto mark_active_timed_out;
654
655 _debug("=== OBTAINED_OBJECT ===");
656
657 if (object->new) {
658 /* attach data to a newly constructed terminal object */
659 ret = cachefiles_set_object_xattr(object, auxdata);
660 if (ret < 0)
661 goto check_error;
662 } else {
663 /* always update the atime on an object we've just looked up
664 * (this is used to keep track of culling, and atimes are only
665 * updated by read, write and readdir but not lookup or
666 * open) */
667 path.dentry = next;
668 touch_atime(&path);
669 }
670
671 /* open a file interface onto a data file */
672 if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
673 if (d_is_reg(object->dentry)) {
674 const struct address_space_operations *aops;
675
676 ret = -EPERM;
677 aops = d_backing_inode(object->dentry)->i_mapping->a_ops;
678 if (!aops->bmap)
679 goto check_error;
680 if (object->dentry->d_sb->s_blocksize > PAGE_SIZE)
681 goto check_error;
682
683 object->backer = object->dentry;
684 } else {
685 BUG(); // TODO: open file in data-class subdir
686 }
687 }
688
689 object->new = 0;
690 fscache_obtained_object(&object->fscache);
691
692 _leave(" = 0 [%lu]", d_backing_inode(object->dentry)->i_ino);
693 return 0;
694
695no_space_error:
696 fscache_object_mark_killed(&object->fscache, FSCACHE_OBJECT_NO_SPACE);
697create_error:
698 _debug("create error %d", ret);
699 if (ret == -EIO)
700 cachefiles_io_error(cache, "Create/mkdir failed");
701 goto error;
702
703mark_active_timed_out:
704 _debug("mark active timed out");
705 goto release_dentry;
706
707check_error:
708 _debug("check error %d", ret);
709 cachefiles_mark_object_inactive(cache, object);
710release_dentry:
711 dput(object->dentry);
712 object->dentry = NULL;
713 goto error_out;
714
715delete_error:
716 _debug("delete error %d", ret);
717 goto error_out2;
718
719lookup_error:
720 _debug("lookup error %ld", PTR_ERR(next));
721 ret = PTR_ERR(next);
722 if (ret == -EIO)
723 cachefiles_io_error(cache, "Lookup failed");
724 next = NULL;
725error:
726 inode_unlock(d_inode(dir));
727 dput(next);
728error_out2:
729 dput(dir);
730error_out:
731 _leave(" = error %d", -ret);
732 return ret;
733}
734
735/*
736 * get a subdirectory
737 */
738struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
739 struct dentry *dir,
740 const char *dirname)
741{
742 struct dentry *subdir;
743 unsigned long start;
744 struct path path;
745 int ret;
746
747 _enter(",,%s", dirname);
748
749 /* search the current directory for the element name */
750 inode_lock(d_inode(dir));
751
752 start = jiffies;
753 subdir = lookup_one_len(dirname, dir, strlen(dirname));
754 cachefiles_hist(cachefiles_lookup_histogram, start);
755 if (IS_ERR(subdir)) {
756 if (PTR_ERR(subdir) == -ENOMEM)
757 goto nomem_d_alloc;
758 goto lookup_error;
759 }
760
761 _debug("subdir -> %p %s",
762 subdir, d_backing_inode(subdir) ? "positive" : "negative");
763
764 /* we need to create the subdir if it doesn't exist yet */
765 if (d_is_negative(subdir)) {
766 ret = cachefiles_has_space(cache, 1, 0);
767 if (ret < 0)
768 goto mkdir_error;
769
770 _debug("attempt mkdir");
771
772 path.mnt = cache->mnt;
773 path.dentry = dir;
774 ret = security_path_mkdir(&path, subdir, 0700);
775 if (ret < 0)
776 goto mkdir_error;
777 ret = vfs_mkdir(d_inode(dir), subdir, 0700);
778 if (ret < 0)
779 goto mkdir_error;
780
781 ASSERT(d_backing_inode(subdir));
782
783 _debug("mkdir -> %p{%p{ino=%lu}}",
784 subdir,
785 d_backing_inode(subdir),
786 d_backing_inode(subdir)->i_ino);
787 }
788
789 inode_unlock(d_inode(dir));
790
791 /* we need to make sure the subdir is a directory */
792 ASSERT(d_backing_inode(subdir));
793
794 if (!d_can_lookup(subdir)) {
795 pr_err("%s is not a directory\n", dirname);
796 ret = -EIO;
797 goto check_error;
798 }
799
800 ret = -EPERM;
801 if (!d_backing_inode(subdir)->i_op->setxattr ||
802 !d_backing_inode(subdir)->i_op->getxattr ||
803 !d_backing_inode(subdir)->i_op->lookup ||
804 !d_backing_inode(subdir)->i_op->mkdir ||
805 !d_backing_inode(subdir)->i_op->create ||
806 (!d_backing_inode(subdir)->i_op->rename &&
807 !d_backing_inode(subdir)->i_op->rename2) ||
808 !d_backing_inode(subdir)->i_op->rmdir ||
809 !d_backing_inode(subdir)->i_op->unlink)
810 goto check_error;
811
812 _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
813 return subdir;
814
815check_error:
816 dput(subdir);
817 _leave(" = %d [check]", ret);
818 return ERR_PTR(ret);
819
820mkdir_error:
821 inode_unlock(d_inode(dir));
822 dput(subdir);
823 pr_err("mkdir %s failed with error %d\n", dirname, ret);
824 return ERR_PTR(ret);
825
826lookup_error:
827 inode_unlock(d_inode(dir));
828 ret = PTR_ERR(subdir);
829 pr_err("Lookup %s failed with error %d\n", dirname, ret);
830 return ERR_PTR(ret);
831
832nomem_d_alloc:
833 inode_unlock(d_inode(dir));
834 _leave(" = -ENOMEM");
835 return ERR_PTR(-ENOMEM);
836}
837
838/*
839 * find out if an object is in use or not
840 * - if finds object and it's not in use:
841 * - returns a pointer to the object and a reference on it
842 * - returns with the directory locked
843 */
844static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
845 struct dentry *dir,
846 char *filename)
847{
848 struct cachefiles_object *object;
849 struct rb_node *_n;
850 struct dentry *victim;
851 unsigned long start;
852 int ret;
853
854 //_enter(",%pd/,%s",
855 // dir, filename);
856
857 /* look up the victim */
858 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
859
860 start = jiffies;
861 victim = lookup_one_len(filename, dir, strlen(filename));
862 cachefiles_hist(cachefiles_lookup_histogram, start);
863 if (IS_ERR(victim))
864 goto lookup_error;
865
866 //_debug("victim -> %p %s",
867 // victim, d_backing_inode(victim) ? "positive" : "negative");
868
869 /* if the object is no longer there then we probably retired the object
870 * at the netfs's request whilst the cull was in progress
871 */
872 if (d_is_negative(victim)) {
873 inode_unlock(d_inode(dir));
874 dput(victim);
875 _leave(" = -ENOENT [absent]");
876 return ERR_PTR(-ENOENT);
877 }
878
879 /* check to see if we're using this object */
880 read_lock(&cache->active_lock);
881
882 _n = cache->active_nodes.rb_node;
883
884 while (_n) {
885 object = rb_entry(_n, struct cachefiles_object, active_node);
886
887 if (object->dentry > victim)
888 _n = _n->rb_left;
889 else if (object->dentry < victim)
890 _n = _n->rb_right;
891 else
892 goto object_in_use;
893 }
894
895 read_unlock(&cache->active_lock);
896
897 //_leave(" = %p", victim);
898 return victim;
899
900object_in_use:
901 read_unlock(&cache->active_lock);
902 inode_unlock(d_inode(dir));
903 dput(victim);
904 //_leave(" = -EBUSY [in use]");
905 return ERR_PTR(-EBUSY);
906
907lookup_error:
908 inode_unlock(d_inode(dir));
909 ret = PTR_ERR(victim);
910 if (ret == -ENOENT) {
911 /* file or dir now absent - probably retired by netfs */
912 _leave(" = -ESTALE [absent]");
913 return ERR_PTR(-ESTALE);
914 }
915
916 if (ret == -EIO) {
917 cachefiles_io_error(cache, "Lookup failed");
918 } else if (ret != -ENOMEM) {
919 pr_err("Internal error: %d\n", ret);
920 ret = -EIO;
921 }
922
923 _leave(" = %d", ret);
924 return ERR_PTR(ret);
925}
926
927/*
928 * cull an object if it's not in use
929 * - called only by cache manager daemon
930 */
931int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
932 char *filename)
933{
934 struct dentry *victim;
935 int ret;
936
937 _enter(",%pd/,%s", dir, filename);
938
939 victim = cachefiles_check_active(cache, dir, filename);
940 if (IS_ERR(victim))
941 return PTR_ERR(victim);
942
943 _debug("victim -> %p %s",
944 victim, d_backing_inode(victim) ? "positive" : "negative");
945
946 /* okay... the victim is not being used so we can cull it
947 * - start by marking it as stale
948 */
949 _debug("victim is cullable");
950
951 ret = cachefiles_remove_object_xattr(cache, victim);
952 if (ret < 0)
953 goto error_unlock;
954
955 /* actually remove the victim (drops the dir mutex) */
956 _debug("bury");
957
958 ret = cachefiles_bury_object(cache, dir, victim, false,
959 FSCACHE_OBJECT_WAS_CULLED);
960 if (ret < 0)
961 goto error;
962
963 dput(victim);
964 _leave(" = 0");
965 return 0;
966
967error_unlock:
968 inode_unlock(d_inode(dir));
969error:
970 dput(victim);
971 if (ret == -ENOENT) {
972 /* file or dir now absent - probably retired by netfs */
973 _leave(" = -ESTALE [absent]");
974 return -ESTALE;
975 }
976
977 if (ret != -ENOMEM) {
978 pr_err("Internal error: %d\n", ret);
979 ret = -EIO;
980 }
981
982 _leave(" = %d", ret);
983 return ret;
984}
985
986/*
987 * find out if an object is in use or not
988 * - called only by cache manager daemon
989 * - returns -EBUSY or 0 to indicate whether an object is in use or not
990 */
991int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
992 char *filename)
993{
994 struct dentry *victim;
995
996 //_enter(",%pd/,%s",
997 // dir, filename);
998
999 victim = cachefiles_check_active(cache, dir, filename);
1000 if (IS_ERR(victim))
1001 return PTR_ERR(victim);
1002
1003 inode_unlock(d_inode(dir));
1004 dput(victim);
1005 //_leave(" = 0");
1006 return 0;
1007}