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 */
17static 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(obj: object, inode);
25 can_use = true;
26 } else {
27 trace_cachefiles_mark_failed(obj: object, inode);
28 }
29
30 return can_use;
31}
32
33static 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 */
47static 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(obj: object, inode);
52}
53
54static 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 */
66void 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(f: 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(i: inode->i_blocks, v: &cache->b_released);
76 if (atomic_inc_return(v: &cache->f_released))
77 cachefiles_state_changed(cache);
78 }
79}
80
81/*
82 * get a subdirectory
83 */
84struct 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(inode: d_inode(dentry: dir), subclass: I_MUTEX_PARENT);
97
98retry:
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(error: ret);
104 trace_cachefiles_lookup(NULL, dir, de: subdir);
105 if (IS_ERR(ptr: subdir)) {
106 trace_cachefiles_vfs_error(NULL, backer: d_backing_inode(upper: dir),
107 error: PTR_ERR(ptr: subdir),
108 where: cachefiles_trace_lookup_error);
109 if (PTR_ERR(ptr: 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(dentry: subdir)) {
119 ret = cachefiles_has_space(cache, fnr: 1, bnr: 0,
120 reason: 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(dir: &path, dentry: subdir, mode: 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(dentry: dir), subdir, 0700);
134 if (ret < 0) {
135 trace_cachefiles_vfs_error(NULL, backer: d_inode(dentry: dir), error: ret,
136 where: 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(dir: 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(inode: d_inode(dentry: subdir));
155 inode_unlock(inode: d_inode(dentry: dir));
156
157 if (!__cachefiles_mark_inode_in_use(NULL, inode: d_inode(dentry: 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(inode: d_inode(dentry: 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(dentry: 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(upper: subdir)->i_opflags & IOP_XATTR) ||
176 !d_backing_inode(upper: subdir)->i_op->lookup ||
177 !d_backing_inode(upper: subdir)->i_op->mkdir ||
178 !d_backing_inode(upper: subdir)->i_op->rename ||
179 !d_backing_inode(upper: subdir)->i_op->rmdir ||
180 !d_backing_inode(upper: subdir)->i_op->unlink)
181 goto check_error;
182
183 _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
184 return subdir;
185
186check_error:
187 cachefiles_put_directory(dir: subdir);
188 _leave(" = %d [check]", ret);
189 return ERR_PTR(error: ret);
190
191mark_error:
192 inode_unlock(inode: d_inode(dentry: subdir));
193 dput(subdir);
194 return ERR_PTR(error: -EBUSY);
195
196mkdir_error:
197 inode_unlock(inode: d_inode(dentry: dir));
198 dput(subdir);
199 pr_err("mkdir %s failed with error %d\n", dirname, ret);
200 return ERR_PTR(error: ret);
201
202lookup_error:
203 inode_unlock(inode: d_inode(dentry: dir));
204 ret = PTR_ERR(ptr: subdir);
205 pr_err("Lookup %s failed with error %d\n", dirname, ret);
206 return ERR_PTR(error: ret);
207
208nomem_d_alloc:
209 inode_unlock(inode: d_inode(dentry: dir));
210 _leave(" = -ENOMEM");
211 return ERR_PTR(error: -ENOMEM);
212}
213
214/*
215 * Put a subdirectory.
216 */
217void cachefiles_put_directory(struct dentry *dir)
218{
219 if (dir) {
220 cachefiles_do_unmark_inode_in_use(NULL, inode: d_inode(dentry: dir));
221 dput(dir);
222 }
223}
224
225/*
226 * Remove a regular file from the cache.
227 */
228static 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(obj: object, ino: d_inode(dentry)->i_ino, why);
240 ret = security_path_unlink(dir: &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(upper: dir), dentry, NULL);
249 if (ret == -EIO)
250 cachefiles_io_error(cache, "Unlink failed");
251 }
252 if (ret != 0)
253 trace_cachefiles_vfs_error(obj: object, backer: d_backing_inode(upper: dir), error: ret,
254 where: 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 */
264int 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(inode: d_inode(dentry: dir));
279 _leave(" = -ESTALE");
280 return -ESTALE;
281 }
282
283 /* non-directories can just be unlinked */
284 if (!d_is_dir(dentry: rep)) {
285 dget(dentry: rep); /* Stop the dentry being negated if it's only pinned
286 * by a file struct.
287 */
288 ret = cachefiles_unlink(cache, object, dir, dentry: rep, why);
289 dput(rep);
290
291 inode_unlock(inode: d_inode(dentry: 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(inode: d_inode(dentry: dir));
299
300try_again:
301 /* first step is to make up a grave dentry in the graveyard */
302 sprintf(buf: nbuffer, fmt: "%08x%08x",
303 (uint32_t) ktime_get_real_seconds(),
304 (uint32_t) atomic_inc_return(v: &cache->gravecounter));
305
306 /* do the multiway lock magic */
307 trap = lock_rename(cache->graveyard, dir);
308
309 /* do some checks before getting the grave dentry */
310 if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) {
311 /* the entry was probably culled when we dropped the parent dir
312 * lock */
313 unlock_rename(cache->graveyard, dir);
314 _leave(" = 0 [culled?]");
315 return 0;
316 }
317
318 if (!d_can_lookup(dentry: cache->graveyard)) {
319 unlock_rename(cache->graveyard, dir);
320 cachefiles_io_error(cache, "Graveyard no longer a directory");
321 return -EIO;
322 }
323
324 if (trap == rep) {
325 unlock_rename(cache->graveyard, dir);
326 cachefiles_io_error(cache, "May not make directory loop");
327 return -EIO;
328 }
329
330 if (d_mountpoint(dentry: rep)) {
331 unlock_rename(cache->graveyard, dir);
332 cachefiles_io_error(cache, "Mountpoint in cache");
333 return -EIO;
334 }
335
336 grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
337 if (IS_ERR(ptr: grave)) {
338 unlock_rename(cache->graveyard, dir);
339 trace_cachefiles_vfs_error(obj: object, backer: d_inode(dentry: cache->graveyard),
340 error: PTR_ERR(ptr: grave),
341 where: cachefiles_trace_lookup_error);
342
343 if (PTR_ERR(ptr: grave) == -ENOMEM) {
344 _leave(" = -ENOMEM");
345 return -ENOMEM;
346 }
347
348 cachefiles_io_error(cache, "Lookup error %ld", PTR_ERR(grave));
349 return -EIO;
350 }
351
352 if (d_is_positive(dentry: grave)) {
353 unlock_rename(cache->graveyard, dir);
354 dput(grave);
355 grave = NULL;
356 cond_resched();
357 goto try_again;
358 }
359
360 if (d_mountpoint(dentry: grave)) {
361 unlock_rename(cache->graveyard, dir);
362 dput(grave);
363 cachefiles_io_error(cache, "Mountpoint in graveyard");
364 return -EIO;
365 }
366
367 /* target should not be an ancestor of source */
368 if (trap == grave) {
369 unlock_rename(cache->graveyard, dir);
370 dput(grave);
371 cachefiles_io_error(cache, "May not make directory loop");
372 return -EIO;
373 }
374
375 /* attempt the rename */
376 path.mnt = cache->mnt;
377 path.dentry = dir;
378 path_to_graveyard.mnt = cache->mnt;
379 path_to_graveyard.dentry = cache->graveyard;
380 ret = security_path_rename(old_dir: &path, old_dentry: rep, new_dir: &path_to_graveyard, new_dentry: grave, flags: 0);
381 if (ret < 0) {
382 cachefiles_io_error(cache, "Rename security error %d", ret);
383 } else {
384 struct renamedata rd = {
385 .old_mnt_idmap = &nop_mnt_idmap,
386 .old_dir = d_inode(dentry: dir),
387 .old_dentry = rep,
388 .new_mnt_idmap = &nop_mnt_idmap,
389 .new_dir = d_inode(dentry: cache->graveyard),
390 .new_dentry = grave,
391 };
392 trace_cachefiles_rename(obj: object, ino: d_inode(dentry: rep)->i_ino, why);
393 ret = cachefiles_inject_read_error();
394 if (ret == 0)
395 ret = vfs_rename(&rd);
396 if (ret != 0)
397 trace_cachefiles_vfs_error(obj: object, backer: d_inode(dentry: dir), error: ret,
398 where: cachefiles_trace_rename_error);
399 if (ret != 0 && ret != -ENOMEM)
400 cachefiles_io_error(cache,
401 "Rename failed with error %d", ret);
402 }
403
404 __cachefiles_unmark_inode_in_use(object, inode: d_inode(dentry: rep));
405 unlock_rename(cache->graveyard, dir);
406 dput(grave);
407 _leave(" = 0");
408 return 0;
409}
410
411/*
412 * Delete a cache file.
413 */
414int cachefiles_delete_object(struct cachefiles_object *object,
415 enum fscache_why_object_killed why)
416{
417 struct cachefiles_volume *volume = object->volume;
418 struct dentry *dentry = object->file->f_path.dentry;
419 struct dentry *fan = volume->fanout[(u8)object->cookie->key_hash];
420 int ret;
421
422 _enter(",OBJ%x{%pD}", object->debug_id, object->file);
423
424 /* Stop the dentry being negated if it's only pinned by a file struct. */
425 dget(dentry);
426
427 inode_lock_nested(inode: d_backing_inode(upper: fan), subclass: I_MUTEX_PARENT);
428 ret = cachefiles_unlink(cache: volume->cache, object, dir: fan, dentry, why);
429 inode_unlock(inode: d_backing_inode(upper: fan));
430 dput(dentry);
431 return ret;
432}
433
434/*
435 * Create a temporary file and leave it unattached and un-xattr'd until the
436 * time comes to discard the object from memory.
437 */
438struct file *cachefiles_create_tmpfile(struct cachefiles_object *object)
439{
440 struct cachefiles_volume *volume = object->volume;
441 struct cachefiles_cache *cache = volume->cache;
442 const struct cred *saved_cred;
443 struct dentry *fan = volume->fanout[(u8)object->cookie->key_hash];
444 struct file *file;
445 const struct path parentpath = { .mnt = cache->mnt, .dentry = fan };
446 uint64_t ni_size;
447 long ret;
448
449
450 cachefiles_begin_secure(cache, saved_cred: &saved_cred);
451
452 ret = cachefiles_inject_write_error();
453 if (ret == 0) {
454 file = kernel_tmpfile_open(idmap: &nop_mnt_idmap, parentpath: &parentpath,
455 S_IFREG | 0600,
456 O_RDWR | O_LARGEFILE | O_DIRECT,
457 cred: cache->cache_cred);
458 ret = PTR_ERR_OR_ZERO(ptr: file);
459 }
460 if (ret) {
461 trace_cachefiles_vfs_error(obj: object, backer: d_inode(dentry: fan), error: ret,
462 where: cachefiles_trace_tmpfile_error);
463 if (ret == -EIO)
464 cachefiles_io_error_obj(object, "Failed to create tmpfile");
465 goto err;
466 }
467
468 trace_cachefiles_tmpfile(obj: object, backer: file_inode(f: file));
469
470 /* This is a newly created file with no other possible user */
471 if (!cachefiles_mark_inode_in_use(object, inode: file_inode(f: file)))
472 WARN_ON(1);
473
474 ret = cachefiles_ondemand_init_object(object);
475 if (ret < 0)
476 goto err_unuse;
477
478 ni_size = object->cookie->object_size;
479 ni_size = round_up(ni_size, CACHEFILES_DIO_BLOCK_SIZE);
480
481 if (ni_size > 0) {
482 trace_cachefiles_trunc(obj: object, backer: file_inode(f: file), from: 0, to: ni_size,
483 why: cachefiles_trunc_expand_tmpfile);
484 ret = cachefiles_inject_write_error();
485 if (ret == 0)
486 ret = vfs_truncate(&file->f_path, ni_size);
487 if (ret < 0) {
488 trace_cachefiles_vfs_error(
489 obj: object, backer: file_inode(f: file), error: ret,
490 where: cachefiles_trace_trunc_error);
491 goto err_unuse;
492 }
493 }
494
495 ret = -EINVAL;
496 if (unlikely(!file->f_op->read_iter) ||
497 unlikely(!file->f_op->write_iter)) {
498 fput(file);
499 pr_notice("Cache does not support read_iter and write_iter\n");
500 goto err_unuse;
501 }
502out:
503 cachefiles_end_secure(cache, saved_cred);
504 return file;
505
506err_unuse:
507 cachefiles_do_unmark_inode_in_use(object, inode: file_inode(f: file));
508 fput(file);
509err:
510 file = ERR_PTR(error: ret);
511 goto out;
512}
513
514/*
515 * Create a new file.
516 */
517static bool cachefiles_create_file(struct cachefiles_object *object)
518{
519 struct file *file;
520 int ret;
521
522 ret = cachefiles_has_space(cache: object->volume->cache, fnr: 1, bnr: 0,
523 reason: cachefiles_has_space_for_create);
524 if (ret < 0)
525 return false;
526
527 file = cachefiles_create_tmpfile(object);
528 if (IS_ERR(ptr: file))
529 return false;
530
531 set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, addr: &object->cookie->flags);
532 set_bit(CACHEFILES_OBJECT_USING_TMPFILE, addr: &object->flags);
533 _debug("create -> %pD{ino=%lu}", file, file_inode(file)->i_ino);
534 object->file = file;
535 return true;
536}
537
538/*
539 * Open an existing file, checking its attributes and replacing it if it is
540 * stale.
541 */
542static bool cachefiles_open_file(struct cachefiles_object *object,
543 struct dentry *dentry)
544{
545 struct cachefiles_cache *cache = object->volume->cache;
546 struct file *file;
547 struct path path;
548 int ret;
549
550 _enter("%pd", dentry);
551
552 if (!cachefiles_mark_inode_in_use(object, inode: d_inode(dentry))) {
553 pr_notice("cachefiles: Inode already in use: %pd (B=%lx)\n",
554 dentry, d_inode(dentry)->i_ino);
555 return false;
556 }
557
558 /* We need to open a file interface onto a data file now as we can't do
559 * it on demand because writeback called from do_exit() sees
560 * current->fs == NULL - which breaks d_path() called from ext4 open.
561 */
562 path.mnt = cache->mnt;
563 path.dentry = dentry;
564 file = kernel_file_open(path: &path, O_RDWR | O_LARGEFILE | O_DIRECT,
565 inode: d_backing_inode(upper: dentry), cred: cache->cache_cred);
566 if (IS_ERR(ptr: file)) {
567 trace_cachefiles_vfs_error(obj: object, backer: d_backing_inode(upper: dentry),
568 error: PTR_ERR(ptr: file),
569 where: cachefiles_trace_open_error);
570 goto error;
571 }
572
573 if (unlikely(!file->f_op->read_iter) ||
574 unlikely(!file->f_op->write_iter)) {
575 pr_notice("Cache does not support read_iter and write_iter\n");
576 goto error_fput;
577 }
578 _debug("file -> %pd positive", dentry);
579
580 ret = cachefiles_ondemand_init_object(object);
581 if (ret < 0)
582 goto error_fput;
583
584 ret = cachefiles_check_auxdata(object, file);
585 if (ret < 0)
586 goto check_failed;
587
588 clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, addr: &object->cookie->flags);
589
590 object->file = file;
591
592 /* Always update the atime on an object we've just looked up (this is
593 * used to keep track of culling, and atimes are only updated by read,
594 * write and readdir but not lookup or open).
595 */
596 touch_atime(&file->f_path);
597 dput(dentry);
598 return true;
599
600check_failed:
601 fscache_cookie_lookup_negative(cookie: object->cookie);
602 cachefiles_unmark_inode_in_use(object, file);
603 fput(file);
604 dput(dentry);
605 if (ret == -ESTALE)
606 return cachefiles_create_file(object);
607 return false;
608
609error_fput:
610 fput(file);
611error:
612 cachefiles_do_unmark_inode_in_use(object, inode: d_inode(dentry));
613 dput(dentry);
614 return false;
615}
616
617/*
618 * walk from the parent object to the child object through the backing
619 * filesystem, creating directories as we go
620 */
621bool cachefiles_look_up_object(struct cachefiles_object *object)
622{
623 struct cachefiles_volume *volume = object->volume;
624 struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash];
625 int ret;
626
627 _enter("OBJ%x,%s,", object->debug_id, object->d_name);
628
629 /* Look up path "cache/vol/fanout/file". */
630 ret = cachefiles_inject_read_error();
631 if (ret == 0)
632 dentry = lookup_positive_unlocked(object->d_name, fan,
633 object->d_name_len);
634 else
635 dentry = ERR_PTR(error: ret);
636 trace_cachefiles_lookup(obj: object, dir: fan, de: dentry);
637 if (IS_ERR(ptr: dentry)) {
638 if (dentry == ERR_PTR(error: -ENOENT))
639 goto new_file;
640 if (dentry == ERR_PTR(error: -EIO))
641 cachefiles_io_error_obj(object, "Lookup failed");
642 return false;
643 }
644
645 if (!d_is_reg(dentry)) {
646 pr_err("%pd is not a file\n", dentry);
647 inode_lock_nested(inode: d_inode(dentry: fan), subclass: I_MUTEX_PARENT);
648 ret = cachefiles_bury_object(cache: volume->cache, object, dir: fan, rep: dentry,
649 why: FSCACHE_OBJECT_IS_WEIRD);
650 dput(dentry);
651 if (ret < 0)
652 return false;
653 goto new_file;
654 }
655
656 if (!cachefiles_open_file(object, dentry))
657 return false;
658
659 _leave(" = t [%lu]", file_inode(object->file)->i_ino);
660 return true;
661
662new_file:
663 fscache_cookie_lookup_negative(cookie: 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 */
670bool 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(inode: d_inode(dentry: fan), subclass: 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(error: ret);
686 if (IS_ERR(ptr: dentry)) {
687 trace_cachefiles_vfs_error(obj: object, backer: d_inode(dentry: fan), error: PTR_ERR(ptr: dentry),
688 where: 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(upper: dentry) == file_inode(f: object->file)) {
695 success = true;
696 goto out_dput;
697 }
698
699 ret = cachefiles_unlink(cache: volume->cache, object, dir: fan, dentry,
700 why: 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(error: ret);
710 if (IS_ERR(ptr: dentry)) {
711 trace_cachefiles_vfs_error(obj: object, backer: d_inode(dentry: fan), error: PTR_ERR(ptr: dentry),
712 where: 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(dentry: fan), dentry, NULL);
722 if (ret < 0) {
723 trace_cachefiles_vfs_error(obj: object, backer: d_inode(dentry: fan), error: ret,
724 where: cachefiles_trace_link_error);
725 _debug("link fail %d", ret);
726 } else {
727 trace_cachefiles_link(obj: object, backer: file_inode(f: object->file));
728 spin_lock(lock: &object->lock);
729 /* TODO: Do we want to switch the file pointer to the new dentry? */
730 clear_bit(CACHEFILES_OBJECT_USING_TMPFILE, addr: &object->flags);
731 spin_unlock(lock: &object->lock);
732 success = true;
733 }
734
735out_dput:
736 dput(dentry);
737out_unlock:
738 inode_unlock(inode: d_inode(dentry: 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 */
747static 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(inode: d_inode(dentry: dir), subclass: I_MUTEX_PARENT);
755
756 victim = lookup_one_len(filename, dir, strlen(filename));
757 if (IS_ERR(ptr: victim))
758 goto lookup_error;
759 if (d_is_negative(dentry: victim))
760 goto lookup_put;
761 if (d_inode(dentry: victim)->i_flags & S_KERNEL_FILE)
762 goto lookup_busy;
763 return victim;
764
765lookup_busy:
766 ret = -EBUSY;
767lookup_put:
768 inode_unlock(inode: d_inode(dentry: dir));
769 dput(victim);
770 return ERR_PTR(error: ret);
771
772lookup_error:
773 inode_unlock(inode: d_inode(dentry: dir));
774 ret = PTR_ERR(ptr: victim);
775 if (ret == -ENOENT)
776 return ERR_PTR(error: -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(error: ret);
786}
787
788/*
789 * Cull an object if it's not in use
790 * - called only by cache manager daemon
791 */
792int 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(ptr: victim))
803 return PTR_ERR(ptr: victim);
804
805 /* check to see if someone is using this object */
806 inode = d_inode(dentry: 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, rep: victim,
820 why: 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
829error_unlock:
830 inode_unlock(inode: d_inode(dentry: dir));
831error:
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 */
850int 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(ptr: victim))
858 return PTR_ERR(ptr: victim);
859
860 inode_unlock(inode: d_inode(dentry: dir));
861 dput(victim);
862 return ret;
863}
864

source code of linux/fs/cachefiles/namei.c