1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* CacheFiles path walking and related routines
3 *
4 * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8 #include <linux/fs.h>
9 #include <linux/namei.h>
10 #include "internal.h"
11
12 /*
13 * Mark the backing file as being a cache file if it's not already in use. The
14 * mark tells the culling request command that it's not allowed to cull the
15 * file or directory. The caller must hold the inode lock.
16 */
17 static bool __cachefiles_mark_inode_in_use(struct cachefiles_object *object,
18 struct inode *inode)
19 {
20 bool can_use = false;
21
22 if (!(inode->i_flags & S_KERNEL_FILE)) {
23 inode->i_flags |= S_KERNEL_FILE;
24 trace_cachefiles_mark_active(object, inode);
25 can_use = true;
26 } else {
27 trace_cachefiles_mark_failed(object, inode);
28 }
29
30 return can_use;
31 }
32
33 static bool cachefiles_mark_inode_in_use(struct cachefiles_object *object,
34 struct inode *inode)
35 {
36 bool can_use;
37
38 inode_lock(inode);
39 can_use = __cachefiles_mark_inode_in_use(object, inode);
40 inode_unlock(inode);
41 return can_use;
42 }
43
44 /*
45 * Unmark a backing inode. The caller must hold the inode lock.
46 */
47 static void __cachefiles_unmark_inode_in_use(struct cachefiles_object *object,
48 struct inode *inode)
49 {
50 inode->i_flags &= ~S_KERNEL_FILE;
51 trace_cachefiles_mark_inactive(object, inode);
52 }
53
54 static void cachefiles_do_unmark_inode_in_use(struct cachefiles_object *object,
55 struct inode *inode)
56 {
57 inode_lock(inode);
58 __cachefiles_unmark_inode_in_use(object, inode);
59 inode_unlock(inode);
60 }
61
62 /*
63 * Unmark a backing inode and tell cachefilesd that there's something that can
64 * be culled.
65 */
66 void cachefiles_unmark_inode_in_use(struct cachefiles_object *object,
67 struct file *file)
68 {
69 struct cachefiles_cache *cache = object->volume->cache;
70 struct inode *inode = file_inode(file);
71
72 cachefiles_do_unmark_inode_in_use(object, inode);
73
74 if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) {
75 atomic_long_add(inode->i_blocks, &cache->b_released);
76 if (atomic_inc_return(&cache->f_released))
77 cachefiles_state_changed(cache);
78 }
79 }
80
81 /*
82 * get a subdirectory
83 */
84 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
85 struct dentry *dir,
86 const char *dirname,
87 bool *_is_new)
88 {
89 struct dentry *subdir;
90 struct path path;
91 int ret;
92
93 _enter(",,%s", dirname);
94
95 /* search the current directory for the element name */
96 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
97
98 retry:
99 ret = cachefiles_inject_read_error();
100 if (ret == 0)
101 subdir = lookup_one_len(dirname, dir, strlen(dirname));
102 else
103 subdir = ERR_PTR(ret);
104 trace_cachefiles_lookup(NULL, dir, subdir);
105 if (IS_ERR(subdir)) {
106 trace_cachefiles_vfs_error(NULL, d_backing_inode(dir),
107 PTR_ERR(subdir),
108 cachefiles_trace_lookup_error);
109 if (PTR_ERR(subdir) == -ENOMEM)
110 goto nomem_d_alloc;
111 goto lookup_error;
112 }
113
114 _debug("subdir -> %pd %s",
115 subdir, d_backing_inode(subdir) ? "positive" : "negative");
116
117 /* we need to create the subdir if it doesn't exist yet */
118 if (d_is_negative(subdir)) {
119 ret = cachefiles_has_space(cache, 1, 0,
120 cachefiles_has_space_for_create);
121 if (ret < 0)
122 goto mkdir_error;
123
124 _debug("attempt mkdir");
125
126 path.mnt = cache->mnt;
127 path.dentry = dir;
128 ret = security_path_mkdir(&path, subdir, 0700);
129 if (ret < 0)
130 goto mkdir_error;
131 ret = cachefiles_inject_write_error();
132 if (ret == 0)
133 ret = vfs_mkdir(&nop_mnt_idmap, d_inode(dir), subdir, 0700);
134 if (ret < 0) {
135 trace_cachefiles_vfs_error(NULL, d_inode(dir), ret,
136 cachefiles_trace_mkdir_error);
137 goto mkdir_error;
138 }
139 trace_cachefiles_mkdir(dir, subdir);
140
141 if (unlikely(d_unhashed(subdir))) {
142 cachefiles_put_directory(subdir);
143 goto retry;
144 }
145 ASSERT(d_backing_inode(subdir));
146
147 _debug("mkdir -> %pd{ino=%lu}",
148 subdir, d_backing_inode(subdir)->i_ino);
149 if (_is_new)
150 *_is_new = true;
151 }
152
153 /* Tell rmdir() it's not allowed to delete the subdir */
154 inode_lock(d_inode(subdir));
155 inode_unlock(d_inode(dir));
156
157 if (!__cachefiles_mark_inode_in_use(NULL, d_inode(subdir))) {
158 pr_notice("cachefiles: Inode already in use: %pd (B=%lx)\n",
159 subdir, d_inode(subdir)->i_ino);
160 goto mark_error;
161 }
162
163 inode_unlock(d_inode(subdir));
164
165 /* we need to make sure the subdir is a directory */
166 ASSERT(d_backing_inode(subdir));
167
168 if (!d_can_lookup(subdir)) {
169 pr_err("%s is not a directory\n", dirname);
170 ret = -EIO;
171 goto check_error;
172 }
173
174 ret = -EPERM;
175 if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) ||
176 !d_backing_inode(subdir)->i_op->lookup ||
177 !d_backing_inode(subdir)->i_op->mkdir ||
178 !d_backing_inode(subdir)->i_op->rename ||
179 !d_backing_inode(subdir)->i_op->rmdir ||
180 !d_backing_inode(subdir)->i_op->unlink)
181 goto check_error;
182
183 _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
184 return subdir;
185
186 check_error:
187 cachefiles_put_directory(subdir);
188 _leave(" = %d [check]", ret);
189 return ERR_PTR(ret);
190
191 mark_error:
192 inode_unlock(d_inode(subdir));
193 dput(subdir);
194 return ERR_PTR(-EBUSY);
195
196 mkdir_error:
197 inode_unlock(d_inode(dir));
198 dput(subdir);
199 pr_err("mkdir %s failed with error %d\n", dirname, ret);
200 return ERR_PTR(ret);
201
202 lookup_error:
203 inode_unlock(d_inode(dir));
204 ret = PTR_ERR(subdir);
205 pr_err("Lookup %s failed with error %d\n", dirname, ret);
206 return ERR_PTR(ret);
207
208 nomem_d_alloc:
209 inode_unlock(d_inode(dir));
210 _leave(" = -ENOMEM");
211 return ERR_PTR(-ENOMEM);
212 }
213
214 /*
215 * Put a subdirectory.
216 */
217 void cachefiles_put_directory(struct dentry *dir)
218 {
219 if (dir) {
220 cachefiles_do_unmark_inode_in_use(NULL, d_inode(dir));
221 dput(dir);
222 }
223 }
224
225 /*
226 * Remove a regular file from the cache.
227 */
228 static int cachefiles_unlink(struct cachefiles_cache *cache,
229 struct cachefiles_object *object,
230 struct dentry *dir, struct dentry *dentry,
231 enum fscache_why_object_killed why)
232 {
233 struct path path = {
234 .mnt = cache->mnt,
235 .dentry = dir,
236 };
237 int ret;
238
239 trace_cachefiles_unlink(object, d_inode(dentry)->i_ino, why);
240 ret = security_path_unlink(&path, dentry);
241 if (ret < 0) {
242 cachefiles_io_error(cache, "Unlink security error");
243 return ret;
244 }
245
246 ret = cachefiles_inject_remove_error();
247 if (ret == 0) {
248 ret = vfs_unlink(&nop_mnt_idmap, d_backing_inode(dir), dentry, NULL);
249 if (ret == -EIO)
250 cachefiles_io_error(cache, "Unlink failed");
251 }
252 if (ret != 0)
253 trace_cachefiles_vfs_error(object, d_backing_inode(dir), ret,
254 cachefiles_trace_unlink_error);
255 return ret;
256 }
257
258 /*
259 * Delete an object representation from the cache
260 * - File backed objects are unlinked
261 * - Directory backed objects are stuffed into the graveyard for userspace to
262 * delete
263 */
264 int cachefiles_bury_object(struct cachefiles_cache *cache,
265 struct cachefiles_object *object,
266 struct dentry *dir,
267 struct dentry *rep,
268 enum fscache_why_object_killed why)
269 {
270 struct dentry *grave, *trap;
271 struct path path, path_to_graveyard;
272 char nbuffer[8 + 8 + 1];
273 int ret;
274
275 _enter(",'%pd','%pd'", dir, rep);
276
277 if (rep->d_parent != dir) {
278 inode_unlock(d_inode(dir));
279 _leave(" = -ESTALE");
280 return -ESTALE;
281 }
282
283 /* non-directories can just be unlinked */
284 if (!d_is_dir(rep)) {
285 dget(rep); /* Stop the dentry being negated if it's only pinned
286 * by a file struct.
287 */
288 ret = cachefiles_unlink(cache, object, dir, rep, why);
289 dput(rep);
290
291 inode_unlock(d_inode(dir));
292 _leave(" = %d", ret);
293 return ret;
294 }
295
296 /* directories have to be moved to the graveyard */
297 _debug("move stale object to graveyard");
298 inode_unlock(d_inode(dir));
299
300 try_again:
301 /* first step is to make up a grave dentry in the graveyard */
302 sprintf(nbuffer, "%08x%08x",
303 (uint32_t) ktime_get_real_seconds(),
304 (uint32_t) atomic_inc_return(&cache->gravecounter));
305
306 /* do the multiway lock magic */
307 trap = lock_rename(cache->graveyard, dir);
308 if (IS_ERR(trap))
309 return PTR_ERR(trap);
310
311 /* do some checks before getting the grave dentry */
312 if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) {
313 /* the entry was probably culled when we dropped the parent dir
314 * lock */
315 unlock_rename(cache->graveyard, dir);
316 _leave(" = 0 [culled?]");
317 return 0;
318 }
319
320 if (!d_can_lookup(cache->graveyard)) {
321 unlock_rename(cache->graveyard, dir);
322 cachefiles_io_error(cache, "Graveyard no longer a directory");
323 return -EIO;
324 }
325
326 if (trap == rep) {
327 unlock_rename(cache->graveyard, dir);
328 cachefiles_io_error(cache, "May not make directory loop");
329 return -EIO;
330 }
331
332 if (d_mountpoint(rep)) {
333 unlock_rename(cache->graveyard, dir);
334 cachefiles_io_error(cache, "Mountpoint in cache");
335 return -EIO;
336 }
337
338 grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
339 if (IS_ERR(grave)) {
340 unlock_rename(cache->graveyard, dir);
341 trace_cachefiles_vfs_error(object, d_inode(cache->graveyard),
342 PTR_ERR(grave),
343 cachefiles_trace_lookup_error);
344
345 if (PTR_ERR(grave) == -ENOMEM) {
346 _leave(" = -ENOMEM");
347 return -ENOMEM;
348 }
349
350 cachefiles_io_error(cache, "Lookup error %ld", PTR_ERR(grave));
351 return -EIO;
352 }
353
354 if (d_is_positive(grave)) {
355 unlock_rename(cache->graveyard, dir);
356 dput(grave);
357 grave = NULL;
358 cond_resched();
359 goto try_again;
360 }
361
362 if (d_mountpoint(grave)) {
363 unlock_rename(cache->graveyard, dir);
364 dput(grave);
365 cachefiles_io_error(cache, "Mountpoint in graveyard");
366 return -EIO;
367 }
368
369 /* target should not be an ancestor of source */
370 if (trap == grave) {
371 unlock_rename(cache->graveyard, dir);
372 dput(grave);
373 cachefiles_io_error(cache, "May not make directory loop");
374 return -EIO;
375 }
376
377 /* attempt the rename */
378 path.mnt = cache->mnt;
379 path.dentry = dir;
380 path_to_graveyard.mnt = cache->mnt;
381 path_to_graveyard.dentry = cache->graveyard;
382 ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0);
383 if (ret < 0) {
384 cachefiles_io_error(cache, "Rename security error %d", ret);
385 } else {
386 struct renamedata rd = {
387 .old_mnt_idmap = &nop_mnt_idmap,
388 .old_dir = d_inode(dir),
389 .old_dentry = rep,
390 .new_mnt_idmap = &nop_mnt_idmap,
391 .new_dir = d_inode(cache->graveyard),
392 .new_dentry = grave,
393 };
394 trace_cachefiles_rename(object, d_inode(rep)->i_ino, why);
395 ret = cachefiles_inject_read_error();
396 if (ret == 0)
397 ret = vfs_rename(&rd);
398 if (ret != 0)
399 trace_cachefiles_vfs_error(object, d_inode(dir), ret,
400 cachefiles_trace_rename_error);
401 if (ret != 0 && ret != -ENOMEM)
402 cachefiles_io_error(cache,
403 "Rename failed with error %d", ret);
404 }
405
406 __cachefiles_unmark_inode_in_use(object, d_inode(rep));
407 unlock_rename(cache->graveyard, dir);
408 dput(grave);
409 _leave(" = 0");
410 return 0;
411 }
412
413 /*
414 * Delete a cache file.
415 */
416 int cachefiles_delete_object(struct cachefiles_object *object,
417 enum fscache_why_object_killed why)
418 {
419 struct cachefiles_volume *volume = object->volume;
420 struct dentry *dentry = object->file->f_path.dentry;
421 struct dentry *fan = volume->fanout[(u8)object->cookie->key_hash];
422 int ret;
423
424 _enter(",OBJ%x{%pD}", object->debug_id, object->file);
425
426 /* Stop the dentry being negated if it's only pinned by a file struct. */
427 dget(dentry);
428
429 inode_lock_nested(d_backing_inode(fan), I_MUTEX_PARENT);
430 ret = cachefiles_unlink(volume->cache, object, fan, dentry, why);
431 inode_unlock(d_backing_inode(fan));
432 dput(dentry);
433 return ret;
434 }
435
436 /*
437 * Create a temporary file and leave it unattached and un-xattr'd until the
438 * time comes to discard the object from memory.
439 */
440 struct file *cachefiles_create_tmpfile(struct cachefiles_object *object)
441 {
442 struct cachefiles_volume *volume = object->volume;
443 struct cachefiles_cache *cache = volume->cache;
444 const struct cred *saved_cred;
445 struct dentry *fan = volume->fanout[(u8)object->cookie->key_hash];
446 struct file *file;
447 const struct path parentpath = { .mnt = cache->mnt, .dentry = fan };
448 uint64_t ni_size;
449 long ret;
450
451
452 cachefiles_begin_secure(cache, &saved_cred);
453
454 ret = cachefiles_inject_write_error();
455 if (ret == 0) {
456 file = kernel_tmpfile_open(&nop_mnt_idmap, &parentpath,
457 S_IFREG | 0600,
458 O_RDWR | O_LARGEFILE | O_DIRECT,
459 cache->cache_cred);
460 ret = PTR_ERR_OR_ZERO(file);
461 }
462 if (ret) {
463 trace_cachefiles_vfs_error(object, d_inode(fan), ret,
464 cachefiles_trace_tmpfile_error);
465 if (ret == -EIO)
466 cachefiles_io_error_obj(object, "Failed to create tmpfile");
467 goto err;
468 }
469
470 trace_cachefiles_tmpfile(object, file_inode(file));
471
472 /* This is a newly created file with no other possible user */
473 if (!cachefiles_mark_inode_in_use(object, file_inode(file)))
474 WARN_ON(1);
475
476 ret = cachefiles_ondemand_init_object(object);
477 if (ret < 0)
478 goto err_unuse;
479
480 ni_size = object->cookie->object_size;
481 ni_size = round_up(ni_size, CACHEFILES_DIO_BLOCK_SIZE);
482
483 if (ni_size > 0) {
484 trace_cachefiles_trunc(object, file_inode(file), 0, ni_size,
485 cachefiles_trunc_expand_tmpfile);
486 ret = cachefiles_inject_write_error();
487 if (ret == 0)
488 ret = vfs_truncate(&file->f_path, ni_size);
489 if (ret < 0) {
490 trace_cachefiles_vfs_error(
491 object, file_inode(file), ret,
492 cachefiles_trace_trunc_error);
493 goto err_unuse;
494 }
495 }
496
497 ret = -EINVAL;
498 if (unlikely(!file->f_op->read_iter) ||
499 unlikely(!file->f_op->write_iter)) {
500 fput(file);
501 pr_notice("Cache does not support read_iter and write_iter\n");
502 goto err_unuse;
503 }
504 out:
505 cachefiles_end_secure(cache, saved_cred);
506 return file;
507
508 err_unuse:
509 cachefiles_do_unmark_inode_in_use(object, file_inode(file));
510 fput(file);
511 err:
512 file = ERR_PTR(ret);
513 goto out;
514 }
515
516 /*
517 * Create a new file.
518 */
519 static bool cachefiles_create_file(struct cachefiles_object *object)
520 {
521 struct file *file;
522 int ret;
523
524 ret = cachefiles_has_space(object->volume->cache, 1, 0,
525 cachefiles_has_space_for_create);
526 if (ret < 0)
527 return false;
528
529 file = cachefiles_create_tmpfile(object);
530 if (IS_ERR(file))
531 return false;
532
533 set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags);
534 set_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags);
535 _debug("create -> %pD{ino=%lu}", file, file_inode(file)->i_ino);
536 object->file = file;
537 return true;
538 }
539
540 /*
541 * Open an existing file, checking its attributes and replacing it if it is
542 * stale.
543 */
544 static bool cachefiles_open_file(struct cachefiles_object *object,
545 struct dentry *dentry)
546 {
547 struct cachefiles_cache *cache = object->volume->cache;
548 struct file *file;
549 struct path path;
550 int ret;
551
552 _enter("%pd", dentry);
553
554 if (!cachefiles_mark_inode_in_use(object, d_inode(dentry))) {
555 pr_notice("cachefiles: Inode already in use: %pd (B=%lx)\n",
556 dentry, d_inode(dentry)->i_ino);
557 return false;
558 }
559
560 /* We need to open a file interface onto a data file now as we can't do
561 * it on demand because writeback called from do_exit() sees
562 * current->fs == NULL - which breaks d_path() called from ext4 open.
563 */
564 path.mnt = cache->mnt;
565 path.dentry = dentry;
566 file = kernel_file_open(&path, O_RDWR | O_LARGEFILE | O_DIRECT, cache->cache_cred);
567 if (IS_ERR(file)) {
568 trace_cachefiles_vfs_error(object, d_backing_inode(dentry),
569 PTR_ERR(file),
570 cachefiles_trace_open_error);
571 goto error;
572 }
573
574 if (unlikely(!file->f_op->read_iter) ||
575 unlikely(!file->f_op->write_iter)) {
576 pr_notice("Cache does not support read_iter and write_iter\n");
577 goto error_fput;
578 }
579 _debug("file -> %pd positive", dentry);
580
581 ret = cachefiles_ondemand_init_object(object);
582 if (ret < 0)
583 goto error_fput;
584
585 ret = cachefiles_check_auxdata(object, file);
586 if (ret < 0)
587 goto check_failed;
588
589 clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &object->cookie->flags);
590
591 object->file = file;
592
593 /* Always update the atime on an object we've just looked up (this is
594 * used to keep track of culling, and atimes are only updated by read,
595 * write and readdir but not lookup or open).
596 */
597 touch_atime(&file->f_path);
598 return true;
599
600 check_failed:
601 fscache_cookie_lookup_negative(object->cookie);
602 cachefiles_unmark_inode_in_use(object, file);
603 fput(file);
604 if (ret == -ESTALE)
605 return cachefiles_create_file(object);
606 return false;
607
608 error_fput:
609 fput(file);
610 error:
611 cachefiles_do_unmark_inode_in_use(object, d_inode(dentry));
612 return false;
613 }
614
615 /*
616 * walk from the parent object to the child object through the backing
617 * filesystem, creating directories as we go
618 */
619 bool cachefiles_look_up_object(struct cachefiles_object *object)
620 {
621 struct cachefiles_volume *volume = object->volume;
622 struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash];
623 int ret;
624
625 _enter("OBJ%x,%s,", object->debug_id, object->d_name);
626
627 /* Look up path "cache/vol/fanout/file". */
628 ret = cachefiles_inject_read_error();
629 if (ret == 0)
630 dentry = lookup_positive_unlocked(object->d_name, fan,
631 object->d_name_len);
632 else
633 dentry = ERR_PTR(ret);
634 trace_cachefiles_lookup(object, fan, dentry);
635 if (IS_ERR(dentry)) {
636 if (dentry == ERR_PTR(-ENOENT))
637 goto new_file;
638 if (dentry == ERR_PTR(-EIO))
639 cachefiles_io_error_obj(object, "Lookup failed");
640 return false;
641 }
642
643 if (!d_is_reg(dentry)) {
644 pr_err("%pd is not a file\n", dentry);
645 inode_lock_nested(d_inode(fan), I_MUTEX_PARENT);
646 ret = cachefiles_bury_object(volume->cache, object, fan, dentry,
647 FSCACHE_OBJECT_IS_WEIRD);
648 dput(dentry);
649 if (ret < 0)
650 return false;
651 goto new_file;
652 }
653
654 ret = cachefiles_open_file(object, dentry);
655 dput(dentry);
656 if (!ret)
657 return false;
658
659 _leave(" = t [%lu]", file_inode(object->file)->i_ino);
660 return true;
661
662 new_file:
663 fscache_cookie_lookup_negative(object->cookie);
664 return cachefiles_create_file(object);
665 }
666
667 /*
668 * Attempt to link a temporary file into its rightful place in the cache.
669 */
670 bool cachefiles_commit_tmpfile(struct cachefiles_cache *cache,
671 struct cachefiles_object *object)
672 {
673 struct cachefiles_volume *volume = object->volume;
674 struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash];
675 bool success = false;
676 int ret;
677
678 _enter(",%pD", object->file);
679
680 inode_lock_nested(d_inode(fan), I_MUTEX_PARENT);
681 ret = cachefiles_inject_read_error();
682 if (ret == 0)
683 dentry = lookup_one_len(object->d_name, fan, object->d_name_len);
684 else
685 dentry = ERR_PTR(ret);
686 if (IS_ERR(dentry)) {
687 trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(dentry),
688 cachefiles_trace_lookup_error);
689 _debug("lookup fail %ld", PTR_ERR(dentry));
690 goto out_unlock;
691 }
692
693 if (!d_is_negative(dentry)) {
694 if (d_backing_inode(dentry) == file_inode(object->file)) {
695 success = true;
696 goto out_dput;
697 }
698
699 ret = cachefiles_unlink(volume->cache, object, fan, dentry,
700 FSCACHE_OBJECT_IS_STALE);
701 if (ret < 0)
702 goto out_dput;
703
704 dput(dentry);
705 ret = cachefiles_inject_read_error();
706 if (ret == 0)
707 dentry = lookup_one_len(object->d_name, fan, object->d_name_len);
708 else
709 dentry = ERR_PTR(ret);
710 if (IS_ERR(dentry)) {
711 trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(dentry),
712 cachefiles_trace_lookup_error);
713 _debug("lookup fail %ld", PTR_ERR(dentry));
714 goto out_unlock;
715 }
716 }
717
718 ret = cachefiles_inject_read_error();
719 if (ret == 0)
720 ret = vfs_link(object->file->f_path.dentry, &nop_mnt_idmap,
721 d_inode(fan), dentry, NULL);
722 if (ret < 0) {
723 trace_cachefiles_vfs_error(object, d_inode(fan), ret,
724 cachefiles_trace_link_error);
725 _debug("link fail %d", ret);
726 } else {
727 trace_cachefiles_link(object, file_inode(object->file));
728 spin_lock(&object->lock);
729 /* TODO: Do we want to switch the file pointer to the new dentry? */
730 clear_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags);
731 spin_unlock(&object->lock);
732 success = true;
733 }
734
735 out_dput:
736 dput(dentry);
737 out_unlock:
738 inode_unlock(d_inode(fan));
739 _leave(" = %u", success);
740 return success;
741 }
742
743 /*
744 * Look up an inode to be checked or culled. Return -EBUSY if the inode is
745 * marked in use.
746 */
747 static struct dentry *cachefiles_lookup_for_cull(struct cachefiles_cache *cache,
748 struct dentry *dir,
749 char *filename)
750 {
751 struct dentry *victim;
752 int ret = -ENOENT;
753
754 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
755
756 victim = lookup_one_len(filename, dir, strlen(filename));
757 if (IS_ERR(victim))
758 goto lookup_error;
759 if (d_is_negative(victim))
760 goto lookup_put;
761 if (d_inode(victim)->i_flags & S_KERNEL_FILE)
762 goto lookup_busy;
763 return victim;
764
765 lookup_busy:
766 ret = -EBUSY;
767 lookup_put:
768 inode_unlock(d_inode(dir));
769 dput(victim);
770 return ERR_PTR(ret);
771
772 lookup_error:
773 inode_unlock(d_inode(dir));
774 ret = PTR_ERR(victim);
775 if (ret == -ENOENT)
776 return ERR_PTR(-ESTALE); /* Probably got retired by the netfs */
777
778 if (ret == -EIO) {
779 cachefiles_io_error(cache, "Lookup failed");
780 } else if (ret != -ENOMEM) {
781 pr_err("Internal error: %d\n", ret);
782 ret = -EIO;
783 }
784
785 return ERR_PTR(ret);
786 }
787
788 /*
789 * Cull an object if it's not in use
790 * - called only by cache manager daemon
791 */
792 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
793 char *filename)
794 {
795 struct dentry *victim;
796 struct inode *inode;
797 int ret;
798
799 _enter(",%pd/,%s", dir, filename);
800
801 victim = cachefiles_lookup_for_cull(cache, dir, filename);
802 if (IS_ERR(victim))
803 return PTR_ERR(victim);
804
805 /* check to see if someone is using this object */
806 inode = d_inode(victim);
807 inode_lock(inode);
808 if (inode->i_flags & S_KERNEL_FILE) {
809 ret = -EBUSY;
810 } else {
811 /* Stop the cache from picking it back up */
812 inode->i_flags |= S_KERNEL_FILE;
813 ret = 0;
814 }
815 inode_unlock(inode);
816 if (ret < 0)
817 goto error_unlock;
818
819 ret = cachefiles_bury_object(cache, NULL, dir, victim,
820 FSCACHE_OBJECT_WAS_CULLED);
821 if (ret < 0)
822 goto error;
823
824 fscache_count_culled();
825 dput(victim);
826 _leave(" = 0");
827 return 0;
828
829 error_unlock:
830 inode_unlock(d_inode(dir));
831 error:
832 dput(victim);
833 if (ret == -ENOENT)
834 return -ESTALE; /* Probably got retired by the netfs */
835
836 if (ret != -ENOMEM) {
837 pr_err("Internal error: %d\n", ret);
838 ret = -EIO;
839 }
840
841 _leave(" = %d", ret);
842 return ret;
843 }
844
845 /*
846 * Find out if an object is in use or not
847 * - called only by cache manager daemon
848 * - returns -EBUSY or 0 to indicate whether an object is in use or not
849 */
850 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
851 char *filename)
852 {
853 struct dentry *victim;
854 int ret = 0;
855
856 victim = cachefiles_lookup_for_cull(cache, dir, filename);
857 if (IS_ERR(victim))
858 return PTR_ERR(victim);
859
860 inode_unlock(d_inode(dir));
861 dput(victim);
862 return ret;
863 }
864
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