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 if (IS_ERR(ptr: trap))
309 return PTR_ERR(ptr: 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(dentry: 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(dentry: 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(ptr: grave)) {
340 unlock_rename(cache->graveyard, dir);
341 trace_cachefiles_vfs_error(obj: object, backer: d_inode(dentry: cache->graveyard),
342 error: PTR_ERR(ptr: grave),
343 where: cachefiles_trace_lookup_error);
344
345 if (PTR_ERR(ptr: 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(dentry: 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(dentry: 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(old_dir: &path, old_dentry: rep, new_dir: &path_to_graveyard, new_dentry: grave, flags: 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(dentry: dir),
389 .old_dentry = rep,
390 .new_mnt_idmap = &nop_mnt_idmap,
391 .new_dir = d_inode(dentry: cache->graveyard),
392 .new_dentry = grave,
393 };
394 trace_cachefiles_rename(obj: object, ino: d_inode(dentry: 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(obj: object, backer: d_inode(dentry: dir), error: ret,
400 where: 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, inode: d_inode(dentry: 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 */
416int 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(inode: d_backing_inode(upper: fan), subclass: I_MUTEX_PARENT);
430 ret = cachefiles_unlink(cache: volume->cache, object, dir: fan, dentry, why);
431 inode_unlock(inode: d_backing_inode(upper: 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 */
440struct 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: &saved_cred);
453
454 ret = cachefiles_inject_write_error();
455 if (ret == 0) {
456 file = kernel_tmpfile_open(idmap: &nop_mnt_idmap, parentpath: &parentpath,
457 S_IFREG | 0600,
458 O_RDWR | O_LARGEFILE | O_DIRECT,
459 cred: cache->cache_cred);
460 ret = PTR_ERR_OR_ZERO(ptr: file);
461 }
462 if (ret) {
463 trace_cachefiles_vfs_error(obj: object, backer: d_inode(dentry: fan), error: ret,
464 where: 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(obj: object, backer: file_inode(f: file));
471
472 /* This is a newly created file with no other possible user */
473 if (!cachefiles_mark_inode_in_use(object, inode: file_inode(f: 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(obj: object, backer: file_inode(f: file), from: 0, to: ni_size,
485 why: 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 obj: object, backer: file_inode(f: file), error: ret,
492 where: 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 }
504out:
505 cachefiles_end_secure(cache, saved_cred);
506 return file;
507
508err_unuse:
509 cachefiles_do_unmark_inode_in_use(object, inode: file_inode(f: file));
510 fput(file);
511err:
512 file = ERR_PTR(error: ret);
513 goto out;
514}
515
516/*
517 * Create a new file.
518 */
519static bool cachefiles_create_file(struct cachefiles_object *object)
520{
521 struct file *file;
522 int ret;
523
524 ret = cachefiles_has_space(cache: object->volume->cache, fnr: 1, bnr: 0,
525 reason: cachefiles_has_space_for_create);
526 if (ret < 0)
527 return false;
528
529 file = cachefiles_create_tmpfile(object);
530 if (IS_ERR(ptr: file))
531 return false;
532
533 set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, addr: &object->cookie->flags);
534 set_bit(CACHEFILES_OBJECT_USING_TMPFILE, addr: &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 */
544static 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, inode: 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: &path, O_RDWR | O_LARGEFILE | O_DIRECT,
567 inode: d_backing_inode(upper: dentry), cred: cache->cache_cred);
568 if (IS_ERR(ptr: file)) {
569 trace_cachefiles_vfs_error(obj: object, backer: d_backing_inode(upper: dentry),
570 error: PTR_ERR(ptr: file),
571 where: cachefiles_trace_open_error);
572 goto error;
573 }
574
575 if (unlikely(!file->f_op->read_iter) ||
576 unlikely(!file->f_op->write_iter)) {
577 pr_notice("Cache does not support read_iter and write_iter\n");
578 goto error_fput;
579 }
580 _debug("file -> %pd positive", dentry);
581
582 ret = cachefiles_ondemand_init_object(object);
583 if (ret < 0)
584 goto error_fput;
585
586 ret = cachefiles_check_auxdata(object, file);
587 if (ret < 0)
588 goto check_failed;
589
590 clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, addr: &object->cookie->flags);
591
592 object->file = file;
593
594 /* Always update the atime on an object we've just looked up (this is
595 * used to keep track of culling, and atimes are only updated by read,
596 * write and readdir but not lookup or open).
597 */
598 touch_atime(&file->f_path);
599 dput(dentry);
600 return true;
601
602check_failed:
603 fscache_cookie_lookup_negative(cookie: object->cookie);
604 cachefiles_unmark_inode_in_use(object, file);
605 fput(file);
606 dput(dentry);
607 if (ret == -ESTALE)
608 return cachefiles_create_file(object);
609 return false;
610
611error_fput:
612 fput(file);
613error:
614 cachefiles_do_unmark_inode_in_use(object, inode: d_inode(dentry));
615 dput(dentry);
616 return false;
617}
618
619/*
620 * walk from the parent object to the child object through the backing
621 * filesystem, creating directories as we go
622 */
623bool cachefiles_look_up_object(struct cachefiles_object *object)
624{
625 struct cachefiles_volume *volume = object->volume;
626 struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash];
627 int ret;
628
629 _enter("OBJ%x,%s,", object->debug_id, object->d_name);
630
631 /* Look up path "cache/vol/fanout/file". */
632 ret = cachefiles_inject_read_error();
633 if (ret == 0)
634 dentry = lookup_positive_unlocked(object->d_name, fan,
635 object->d_name_len);
636 else
637 dentry = ERR_PTR(error: ret);
638 trace_cachefiles_lookup(obj: object, dir: fan, de: dentry);
639 if (IS_ERR(ptr: dentry)) {
640 if (dentry == ERR_PTR(error: -ENOENT))
641 goto new_file;
642 if (dentry == ERR_PTR(error: -EIO))
643 cachefiles_io_error_obj(object, "Lookup failed");
644 return false;
645 }
646
647 if (!d_is_reg(dentry)) {
648 pr_err("%pd is not a file\n", dentry);
649 inode_lock_nested(inode: d_inode(dentry: fan), subclass: I_MUTEX_PARENT);
650 ret = cachefiles_bury_object(cache: volume->cache, object, dir: fan, rep: dentry,
651 why: FSCACHE_OBJECT_IS_WEIRD);
652 dput(dentry);
653 if (ret < 0)
654 return false;
655 goto new_file;
656 }
657
658 if (!cachefiles_open_file(object, dentry))
659 return false;
660
661 _leave(" = t [%lu]", file_inode(object->file)->i_ino);
662 return true;
663
664new_file:
665 fscache_cookie_lookup_negative(cookie: object->cookie);
666 return cachefiles_create_file(object);
667}
668
669/*
670 * Attempt to link a temporary file into its rightful place in the cache.
671 */
672bool cachefiles_commit_tmpfile(struct cachefiles_cache *cache,
673 struct cachefiles_object *object)
674{
675 struct cachefiles_volume *volume = object->volume;
676 struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash];
677 bool success = false;
678 int ret;
679
680 _enter(",%pD", object->file);
681
682 inode_lock_nested(inode: d_inode(dentry: fan), subclass: I_MUTEX_PARENT);
683 ret = cachefiles_inject_read_error();
684 if (ret == 0)
685 dentry = lookup_one_len(object->d_name, fan, object->d_name_len);
686 else
687 dentry = ERR_PTR(error: ret);
688 if (IS_ERR(ptr: dentry)) {
689 trace_cachefiles_vfs_error(obj: object, backer: d_inode(dentry: fan), error: PTR_ERR(ptr: dentry),
690 where: cachefiles_trace_lookup_error);
691 _debug("lookup fail %ld", PTR_ERR(dentry));
692 goto out_unlock;
693 }
694
695 if (!d_is_negative(dentry)) {
696 if (d_backing_inode(upper: dentry) == file_inode(f: object->file)) {
697 success = true;
698 goto out_dput;
699 }
700
701 ret = cachefiles_unlink(cache: volume->cache, object, dir: fan, dentry,
702 why: FSCACHE_OBJECT_IS_STALE);
703 if (ret < 0)
704 goto out_dput;
705
706 dput(dentry);
707 ret = cachefiles_inject_read_error();
708 if (ret == 0)
709 dentry = lookup_one_len(object->d_name, fan, object->d_name_len);
710 else
711 dentry = ERR_PTR(error: ret);
712 if (IS_ERR(ptr: dentry)) {
713 trace_cachefiles_vfs_error(obj: object, backer: d_inode(dentry: fan), error: PTR_ERR(ptr: dentry),
714 where: cachefiles_trace_lookup_error);
715 _debug("lookup fail %ld", PTR_ERR(dentry));
716 goto out_unlock;
717 }
718 }
719
720 ret = cachefiles_inject_read_error();
721 if (ret == 0)
722 ret = vfs_link(object->file->f_path.dentry, &nop_mnt_idmap,
723 d_inode(dentry: fan), dentry, NULL);
724 if (ret < 0) {
725 trace_cachefiles_vfs_error(obj: object, backer: d_inode(dentry: fan), error: ret,
726 where: cachefiles_trace_link_error);
727 _debug("link fail %d", ret);
728 } else {
729 trace_cachefiles_link(obj: object, backer: file_inode(f: object->file));
730 spin_lock(lock: &object->lock);
731 /* TODO: Do we want to switch the file pointer to the new dentry? */
732 clear_bit(CACHEFILES_OBJECT_USING_TMPFILE, addr: &object->flags);
733 spin_unlock(lock: &object->lock);
734 success = true;
735 }
736
737out_dput:
738 dput(dentry);
739out_unlock:
740 inode_unlock(inode: d_inode(dentry: fan));
741 _leave(" = %u", success);
742 return success;
743}
744
745/*
746 * Look up an inode to be checked or culled. Return -EBUSY if the inode is
747 * marked in use.
748 */
749static struct dentry *cachefiles_lookup_for_cull(struct cachefiles_cache *cache,
750 struct dentry *dir,
751 char *filename)
752{
753 struct dentry *victim;
754 int ret = -ENOENT;
755
756 inode_lock_nested(inode: d_inode(dentry: dir), subclass: I_MUTEX_PARENT);
757
758 victim = lookup_one_len(filename, dir, strlen(filename));
759 if (IS_ERR(ptr: victim))
760 goto lookup_error;
761 if (d_is_negative(dentry: victim))
762 goto lookup_put;
763 if (d_inode(dentry: victim)->i_flags & S_KERNEL_FILE)
764 goto lookup_busy;
765 return victim;
766
767lookup_busy:
768 ret = -EBUSY;
769lookup_put:
770 inode_unlock(inode: d_inode(dentry: dir));
771 dput(victim);
772 return ERR_PTR(error: ret);
773
774lookup_error:
775 inode_unlock(inode: d_inode(dentry: dir));
776 ret = PTR_ERR(ptr: victim);
777 if (ret == -ENOENT)
778 return ERR_PTR(error: -ESTALE); /* Probably got retired by the netfs */
779
780 if (ret == -EIO) {
781 cachefiles_io_error(cache, "Lookup failed");
782 } else if (ret != -ENOMEM) {
783 pr_err("Internal error: %d\n", ret);
784 ret = -EIO;
785 }
786
787 return ERR_PTR(error: ret);
788}
789
790/*
791 * Cull an object if it's not in use
792 * - called only by cache manager daemon
793 */
794int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
795 char *filename)
796{
797 struct dentry *victim;
798 struct inode *inode;
799 int ret;
800
801 _enter(",%pd/,%s", dir, filename);
802
803 victim = cachefiles_lookup_for_cull(cache, dir, filename);
804 if (IS_ERR(ptr: victim))
805 return PTR_ERR(ptr: victim);
806
807 /* check to see if someone is using this object */
808 inode = d_inode(dentry: victim);
809 inode_lock(inode);
810 if (inode->i_flags & S_KERNEL_FILE) {
811 ret = -EBUSY;
812 } else {
813 /* Stop the cache from picking it back up */
814 inode->i_flags |= S_KERNEL_FILE;
815 ret = 0;
816 }
817 inode_unlock(inode);
818 if (ret < 0)
819 goto error_unlock;
820
821 ret = cachefiles_bury_object(cache, NULL, dir, rep: victim,
822 why: FSCACHE_OBJECT_WAS_CULLED);
823 if (ret < 0)
824 goto error;
825
826 fscache_count_culled();
827 dput(victim);
828 _leave(" = 0");
829 return 0;
830
831error_unlock:
832 inode_unlock(inode: d_inode(dentry: dir));
833error:
834 dput(victim);
835 if (ret == -ENOENT)
836 return -ESTALE; /* Probably got retired by the netfs */
837
838 if (ret != -ENOMEM) {
839 pr_err("Internal error: %d\n", ret);
840 ret = -EIO;
841 }
842
843 _leave(" = %d", ret);
844 return ret;
845}
846
847/*
848 * Find out if an object is in use or not
849 * - called only by cache manager daemon
850 * - returns -EBUSY or 0 to indicate whether an object is in use or not
851 */
852int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
853 char *filename)
854{
855 struct dentry *victim;
856 int ret = 0;
857
858 victim = cachefiles_lookup_for_cull(cache, dir, filename);
859 if (IS_ERR(ptr: victim))
860 return PTR_ERR(ptr: victim);
861
862 inode_unlock(inode: d_inode(dentry: dir));
863 dput(victim);
864 return ret;
865}
866

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