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