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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(object, inode);
25 can_use = true;
26 } else {
27 trace_cachefiles_mark_failed(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(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(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 */
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(d_inode(dir), 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(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
186check_error:
187 cachefiles_put_directory(subdir);
188 _leave(" = %d [check]", ret);
189 return ERR_PTR(ret);
190
191mark_error:
192 inode_unlock(d_inode(subdir));
193 dput(subdir);
194 return ERR_PTR(-EBUSY);
195
196mkdir_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
202lookup_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
208nomem_d_alloc:
209 inode_unlock(d_inode(dir));
210 _leave(" = -ENOMEM");
211 return ERR_PTR(-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, d_inode(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(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 */
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(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
300try_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 */
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(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 */
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);
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 }
504out:
505 cachefiles_end_secure(cache, saved_cred);
506 return file;
507
508err_unuse:
509 cachefiles_do_unmark_inode_in_use(object, file_inode(file));
510 fput(file);
511err:
512 file = ERR_PTR(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(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 */
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, 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,
567 d_backing_inode(dentry), cache->cache_cred);
568 if (IS_ERR(file)) {
569 trace_cachefiles_vfs_error(object, d_backing_inode(dentry),
570 PTR_ERR(file),
571 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, &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(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, 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(ret);
638 trace_cachefiles_lookup(object, fan, dentry);
639 if (IS_ERR(dentry)) {
640 if (dentry == ERR_PTR(-ENOENT))
641 goto new_file;
642 if (dentry == ERR_PTR(-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(d_inode(fan), I_MUTEX_PARENT);
650 ret = cachefiles_bury_object(volume->cache, object, fan, dentry,
651 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(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(d_inode(fan), 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(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 if (d_backing_inode(dentry) == file_inode(object->file)) {
697 success = true;
698 goto out_dput;
699 }
700
701 ret = cachefiles_unlink(volume->cache, object, fan, dentry,
702 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(ret);
712 if (IS_ERR(dentry)) {
713 trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(dentry),
714 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(fan), dentry, NULL);
724 if (ret < 0) {
725 trace_cachefiles_vfs_error(object, d_inode(fan), ret,
726 cachefiles_trace_link_error);
727 _debug("link fail %d", ret);
728 } else {
729 trace_cachefiles_link(object, file_inode(object->file));
730 spin_lock(&object->lock);
731 /* TODO: Do we want to switch the file pointer to the new dentry? */
732 clear_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags);
733 spin_unlock(&object->lock);
734 success = true;
735 }
736
737out_dput:
738 dput(dentry);
739out_unlock:
740 inode_unlock(d_inode(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(d_inode(dir), I_MUTEX_PARENT);
757
758 victim = lookup_one_len(filename, dir, strlen(filename));
759 if (IS_ERR(victim))
760 goto lookup_error;
761 if (d_is_negative(victim))
762 goto lookup_put;
763 if (d_inode(victim)->i_flags & S_KERNEL_FILE)
764 goto lookup_busy;
765 return victim;
766
767lookup_busy:
768 ret = -EBUSY;
769lookup_put:
770 inode_unlock(d_inode(dir));
771 dput(victim);
772 return ERR_PTR(ret);
773
774lookup_error:
775 inode_unlock(d_inode(dir));
776 ret = PTR_ERR(victim);
777 if (ret == -ENOENT)
778 return ERR_PTR(-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(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(victim))
805 return PTR_ERR(victim);
806
807 /* check to see if someone is using this object */
808 inode = d_inode(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, victim,
822 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(d_inode(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(victim))
860 return PTR_ERR(victim);
861
862 inode_unlock(d_inode(dir));
863 dput(victim);
864 return ret;
865}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* CacheFiles path walking and related routines
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/module.h>
9#include <linux/sched.h>
10#include <linux/file.h>
11#include <linux/fs.h>
12#include <linux/fsnotify.h>
13#include <linux/quotaops.h>
14#include <linux/xattr.h>
15#include <linux/mount.h>
16#include <linux/namei.h>
17#include <linux/security.h>
18#include <linux/slab.h>
19#include "internal.h"
20
21#define CACHEFILES_KEYBUF_SIZE 512
22
23/*
24 * dump debugging info about an object
25 */
26static noinline
27void __cachefiles_printk_object(struct cachefiles_object *object,
28 const char *prefix)
29{
30 struct fscache_cookie *cookie;
31 const u8 *k;
32 unsigned loop;
33
34 pr_err("%sobject: OBJ%x\n", prefix, object->fscache.debug_id);
35 pr_err("%sobjstate=%s fl=%lx wbusy=%x ev=%lx[%lx]\n",
36 prefix, object->fscache.state->name,
37 object->fscache.flags, work_busy(&object->fscache.work),
38 object->fscache.events, object->fscache.event_mask);
39 pr_err("%sops=%u inp=%u exc=%u\n",
40 prefix, object->fscache.n_ops, object->fscache.n_in_progress,
41 object->fscache.n_exclusive);
42 pr_err("%sparent=%p\n",
43 prefix, object->fscache.parent);
44
45 spin_lock(&object->fscache.lock);
46 cookie = object->fscache.cookie;
47 if (cookie) {
48 pr_err("%scookie=%p [pr=%p nd=%p fl=%lx]\n",
49 prefix,
50 object->fscache.cookie,
51 object->fscache.cookie->parent,
52 object->fscache.cookie->netfs_data,
53 object->fscache.cookie->flags);
54 pr_err("%skey=[%u] '", prefix, cookie->key_len);
55 k = (cookie->key_len <= sizeof(cookie->inline_key)) ?
56 cookie->inline_key : cookie->key;
57 for (loop = 0; loop < cookie->key_len; loop++)
58 pr_cont("%02x", k[loop]);
59 pr_cont("'\n");
60 } else {
61 pr_err("%scookie=NULL\n", prefix);
62 }
63 spin_unlock(&object->fscache.lock);
64}
65
66/*
67 * dump debugging info about a pair of objects
68 */
69static noinline void cachefiles_printk_object(struct cachefiles_object *object,
70 struct cachefiles_object *xobject)
71{
72 if (object)
73 __cachefiles_printk_object(object, "");
74 if (xobject)
75 __cachefiles_printk_object(xobject, "x");
76}
77
78/*
79 * mark the owner of a dentry, if there is one, to indicate that that dentry
80 * has been preemptively deleted
81 * - the caller must hold the i_mutex on the dentry's parent as required to
82 * call vfs_unlink(), vfs_rmdir() or vfs_rename()
83 */
84static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
85 struct dentry *dentry,
86 enum fscache_why_object_killed why)
87{
88 struct cachefiles_object *object;
89 struct rb_node *p;
90
91 _enter(",'%pd'", dentry);
92
93 write_lock(&cache->active_lock);
94
95 p = cache->active_nodes.rb_node;
96 while (p) {
97 object = rb_entry(p, struct cachefiles_object, active_node);
98 if (object->dentry > dentry)
99 p = p->rb_left;
100 else if (object->dentry < dentry)
101 p = p->rb_right;
102 else
103 goto found_dentry;
104 }
105
106 write_unlock(&cache->active_lock);
107 trace_cachefiles_mark_buried(NULL, dentry, why);
108 _leave(" [no owner]");
109 return;
110
111 /* found the dentry for */
112found_dentry:
113 kdebug("preemptive burial: OBJ%x [%s] %p",
114 object->fscache.debug_id,
115 object->fscache.state->name,
116 dentry);
117
118 trace_cachefiles_mark_buried(object, dentry, why);
119
120 if (fscache_object_is_live(&object->fscache)) {
121 pr_err("\n");
122 pr_err("Error: Can't preemptively bury live object\n");
123 cachefiles_printk_object(object, NULL);
124 } else {
125 if (why != FSCACHE_OBJECT_IS_STALE)
126 fscache_object_mark_killed(&object->fscache, why);
127 }
128
129 write_unlock(&cache->active_lock);
130 _leave(" [owner marked]");
131}
132
133/*
134 * record the fact that an object is now active
135 */
136static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
137 struct cachefiles_object *object)
138{
139 struct cachefiles_object *xobject;
140 struct rb_node **_p, *_parent = NULL;
141 struct dentry *dentry;
142
143 _enter(",%p", object);
144
145try_again:
146 write_lock(&cache->active_lock);
147
148 dentry = object->dentry;
149 trace_cachefiles_mark_active(object, dentry);
150
151 if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
152 pr_err("Error: Object already active\n");
153 cachefiles_printk_object(object, NULL);
154 BUG();
155 }
156
157 _p = &cache->active_nodes.rb_node;
158 while (*_p) {
159 _parent = *_p;
160 xobject = rb_entry(_parent,
161 struct cachefiles_object, active_node);
162
163 ASSERT(xobject != object);
164
165 if (xobject->dentry > dentry)
166 _p = &(*_p)->rb_left;
167 else if (xobject->dentry < dentry)
168 _p = &(*_p)->rb_right;
169 else
170 goto wait_for_old_object;
171 }
172
173 rb_link_node(&object->active_node, _parent, _p);
174 rb_insert_color(&object->active_node, &cache->active_nodes);
175
176 write_unlock(&cache->active_lock);
177 _leave(" = 0");
178 return 0;
179
180 /* an old object from a previous incarnation is hogging the slot - we
181 * need to wait for it to be destroyed */
182wait_for_old_object:
183 trace_cachefiles_wait_active(object, dentry, xobject);
184 clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
185
186 if (fscache_object_is_live(&xobject->fscache)) {
187 pr_err("\n");
188 pr_err("Error: Unexpected object collision\n");
189 cachefiles_printk_object(object, xobject);
190 }
191 atomic_inc(&xobject->usage);
192 write_unlock(&cache->active_lock);
193
194 if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
195 wait_queue_head_t *wq;
196
197 signed long timeout = 60 * HZ;
198 wait_queue_entry_t wait;
199 bool requeue;
200
201 /* if the object we're waiting for is queued for processing,
202 * then just put ourselves on the queue behind it */
203 if (work_pending(&xobject->fscache.work)) {
204 _debug("queue OBJ%x behind OBJ%x immediately",
205 object->fscache.debug_id,
206 xobject->fscache.debug_id);
207 goto requeue;
208 }
209
210 /* otherwise we sleep until either the object we're waiting for
211 * is done, or the fscache_object is congested */
212 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
213 init_wait(&wait);
214 requeue = false;
215 do {
216 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
217 if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
218 break;
219
220 requeue = fscache_object_sleep_till_congested(&timeout);
221 } while (timeout > 0 && !requeue);
222 finish_wait(wq, &wait);
223
224 if (requeue &&
225 test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
226 _debug("queue OBJ%x behind OBJ%x after wait",
227 object->fscache.debug_id,
228 xobject->fscache.debug_id);
229 goto requeue;
230 }
231
232 if (timeout <= 0) {
233 pr_err("\n");
234 pr_err("Error: Overlong wait for old active object to go away\n");
235 cachefiles_printk_object(object, xobject);
236 goto requeue;
237 }
238 }
239
240 ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
241
242 cache->cache.ops->put_object(&xobject->fscache,
243 (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_retry);
244 goto try_again;
245
246requeue:
247 cache->cache.ops->put_object(&xobject->fscache,
248 (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_timeo);
249 _leave(" = -ETIMEDOUT");
250 return -ETIMEDOUT;
251}
252
253/*
254 * Mark an object as being inactive.
255 */
256void cachefiles_mark_object_inactive(struct cachefiles_cache *cache,
257 struct cachefiles_object *object,
258 blkcnt_t i_blocks)
259{
260 struct dentry *dentry = object->dentry;
261 struct inode *inode = d_backing_inode(dentry);
262
263 trace_cachefiles_mark_inactive(object, dentry, inode);
264
265 write_lock(&cache->active_lock);
266 rb_erase(&object->active_node, &cache->active_nodes);
267 clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
268 write_unlock(&cache->active_lock);
269
270 wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
271
272 /* This object can now be culled, so we need to let the daemon know
273 * that there is something it can remove if it needs to.
274 */
275 atomic_long_add(i_blocks, &cache->b_released);
276 if (atomic_inc_return(&cache->f_released))
277 cachefiles_state_changed(cache);
278}
279
280/*
281 * delete an object representation from the cache
282 * - file backed objects are unlinked
283 * - directory backed objects are stuffed into the graveyard for userspace to
284 * delete
285 * - unlocks the directory mutex
286 */
287static int cachefiles_bury_object(struct cachefiles_cache *cache,
288 struct cachefiles_object *object,
289 struct dentry *dir,
290 struct dentry *rep,
291 bool preemptive,
292 enum fscache_why_object_killed why)
293{
294 struct dentry *grave, *trap;
295 struct path path, path_to_graveyard;
296 char nbuffer[8 + 8 + 1];
297 int ret;
298
299 _enter(",'%pd','%pd'", dir, rep);
300
301 _debug("remove %p from %p", rep, dir);
302
303 /* non-directories can just be unlinked */
304 if (!d_is_dir(rep)) {
305 _debug("unlink stale object");
306
307 path.mnt = cache->mnt;
308 path.dentry = dir;
309 ret = security_path_unlink(&path, rep);
310 if (ret < 0) {
311 cachefiles_io_error(cache, "Unlink security error");
312 } else {
313 trace_cachefiles_unlink(object, rep, why);
314 ret = vfs_unlink(d_inode(dir), rep, NULL);
315
316 if (preemptive)
317 cachefiles_mark_object_buried(cache, rep, why);
318 }
319
320 inode_unlock(d_inode(dir));
321
322 if (ret == -EIO)
323 cachefiles_io_error(cache, "Unlink failed");
324
325 _leave(" = %d", ret);
326 return ret;
327 }
328
329 /* directories have to be moved to the graveyard */
330 _debug("move stale object to graveyard");
331 inode_unlock(d_inode(dir));
332
333try_again:
334 /* first step is to make up a grave dentry in the graveyard */
335 sprintf(nbuffer, "%08x%08x",
336 (uint32_t) ktime_get_real_seconds(),
337 (uint32_t) atomic_inc_return(&cache->gravecounter));
338
339 /* do the multiway lock magic */
340 trap = lock_rename(cache->graveyard, dir);
341
342 /* do some checks before getting the grave dentry */
343 if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) {
344 /* the entry was probably culled when we dropped the parent dir
345 * lock */
346 unlock_rename(cache->graveyard, dir);
347 _leave(" = 0 [culled?]");
348 return 0;
349 }
350
351 if (!d_can_lookup(cache->graveyard)) {
352 unlock_rename(cache->graveyard, dir);
353 cachefiles_io_error(cache, "Graveyard no longer a directory");
354 return -EIO;
355 }
356
357 if (trap == rep) {
358 unlock_rename(cache->graveyard, dir);
359 cachefiles_io_error(cache, "May not make directory loop");
360 return -EIO;
361 }
362
363 if (d_mountpoint(rep)) {
364 unlock_rename(cache->graveyard, dir);
365 cachefiles_io_error(cache, "Mountpoint in cache");
366 return -EIO;
367 }
368
369 grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
370 if (IS_ERR(grave)) {
371 unlock_rename(cache->graveyard, dir);
372
373 if (PTR_ERR(grave) == -ENOMEM) {
374 _leave(" = -ENOMEM");
375 return -ENOMEM;
376 }
377
378 cachefiles_io_error(cache, "Lookup error %ld",
379 PTR_ERR(grave));
380 return -EIO;
381 }
382
383 if (d_is_positive(grave)) {
384 unlock_rename(cache->graveyard, dir);
385 dput(grave);
386 grave = NULL;
387 cond_resched();
388 goto try_again;
389 }
390
391 if (d_mountpoint(grave)) {
392 unlock_rename(cache->graveyard, dir);
393 dput(grave);
394 cachefiles_io_error(cache, "Mountpoint in graveyard");
395 return -EIO;
396 }
397
398 /* target should not be an ancestor of source */
399 if (trap == grave) {
400 unlock_rename(cache->graveyard, dir);
401 dput(grave);
402 cachefiles_io_error(cache, "May not make directory loop");
403 return -EIO;
404 }
405
406 /* attempt the rename */
407 path.mnt = cache->mnt;
408 path.dentry = dir;
409 path_to_graveyard.mnt = cache->mnt;
410 path_to_graveyard.dentry = cache->graveyard;
411 ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0);
412 if (ret < 0) {
413 cachefiles_io_error(cache, "Rename security error %d", ret);
414 } else {
415 trace_cachefiles_rename(object, rep, grave, why);
416 ret = vfs_rename(d_inode(dir), rep,
417 d_inode(cache->graveyard), grave, NULL, 0);
418 if (ret != 0 && ret != -ENOMEM)
419 cachefiles_io_error(cache,
420 "Rename failed with error %d", ret);
421
422 if (preemptive)
423 cachefiles_mark_object_buried(cache, rep, why);
424 }
425
426 unlock_rename(cache->graveyard, dir);
427 dput(grave);
428 _leave(" = 0");
429 return 0;
430}
431
432/*
433 * delete an object representation from the cache
434 */
435int cachefiles_delete_object(struct cachefiles_cache *cache,
436 struct cachefiles_object *object)
437{
438 struct dentry *dir;
439 int ret;
440
441 _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
442
443 ASSERT(object->dentry);
444 ASSERT(d_backing_inode(object->dentry));
445 ASSERT(object->dentry->d_parent);
446
447 dir = dget_parent(object->dentry);
448
449 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
450
451 if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
452 /* object allocation for the same key preemptively deleted this
453 * object's file so that it could create its own file */
454 _debug("object preemptively buried");
455 inode_unlock(d_inode(dir));
456 ret = 0;
457 } else {
458 /* we need to check that our parent is _still_ our parent - it
459 * may have been renamed */
460 if (dir == object->dentry->d_parent) {
461 ret = cachefiles_bury_object(cache, object, dir,
462 object->dentry, false,
463 FSCACHE_OBJECT_WAS_RETIRED);
464 } else {
465 /* it got moved, presumably by cachefilesd culling it,
466 * so it's no longer in the key path and we can ignore
467 * it */
468 inode_unlock(d_inode(dir));
469 ret = 0;
470 }
471 }
472
473 dput(dir);
474 _leave(" = %d", ret);
475 return ret;
476}
477
478/*
479 * walk from the parent object to the child object through the backing
480 * filesystem, creating directories as we go
481 */
482int cachefiles_walk_to_object(struct cachefiles_object *parent,
483 struct cachefiles_object *object,
484 const char *key,
485 struct cachefiles_xattr *auxdata)
486{
487 struct cachefiles_cache *cache;
488 struct dentry *dir, *next = NULL;
489 struct inode *inode;
490 struct path path;
491 unsigned long start;
492 const char *name;
493 int ret, nlen;
494
495 _enter("OBJ%x{%p},OBJ%x,%s,",
496 parent->fscache.debug_id, parent->dentry,
497 object->fscache.debug_id, key);
498
499 cache = container_of(parent->fscache.cache,
500 struct cachefiles_cache, cache);
501 path.mnt = cache->mnt;
502
503 ASSERT(parent->dentry);
504 ASSERT(d_backing_inode(parent->dentry));
505
506 if (!(d_is_dir(parent->dentry))) {
507 // TODO: convert file to dir
508 _leave("looking up in none directory");
509 return -ENOBUFS;
510 }
511
512 dir = dget(parent->dentry);
513
514advance:
515 /* attempt to transit the first directory component */
516 name = key;
517 nlen = strlen(key);
518
519 /* key ends in a double NUL */
520 key = key + nlen + 1;
521 if (!*key)
522 key = NULL;
523
524lookup_again:
525 /* search the current directory for the element name */
526 _debug("lookup '%s'", name);
527
528 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
529
530 start = jiffies;
531 next = lookup_one_len(name, dir, nlen);
532 cachefiles_hist(cachefiles_lookup_histogram, start);
533 if (IS_ERR(next)) {
534 trace_cachefiles_lookup(object, next, NULL);
535 goto lookup_error;
536 }
537
538 inode = d_backing_inode(next);
539 trace_cachefiles_lookup(object, next, inode);
540 _debug("next -> %p %s", next, inode ? "positive" : "negative");
541
542 if (!key)
543 object->new = !inode;
544
545 /* if this element of the path doesn't exist, then the lookup phase
546 * failed, and we can release any readers in the certain knowledge that
547 * there's nothing for them to actually read */
548 if (d_is_negative(next))
549 fscache_object_lookup_negative(&object->fscache);
550
551 /* we need to create the object if it's negative */
552 if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
553 /* index objects and intervening tree levels must be subdirs */
554 if (d_is_negative(next)) {
555 ret = cachefiles_has_space(cache, 1, 0);
556 if (ret < 0)
557 goto no_space_error;
558
559 path.dentry = dir;
560 ret = security_path_mkdir(&path, next, 0);
561 if (ret < 0)
562 goto create_error;
563 start = jiffies;
564 ret = vfs_mkdir(d_inode(dir), next, 0);
565 cachefiles_hist(cachefiles_mkdir_histogram, start);
566 if (!key)
567 trace_cachefiles_mkdir(object, next, ret);
568 if (ret < 0)
569 goto create_error;
570
571 if (unlikely(d_unhashed(next))) {
572 dput(next);
573 inode_unlock(d_inode(dir));
574 goto lookup_again;
575 }
576 ASSERT(d_backing_inode(next));
577
578 _debug("mkdir -> %p{%p{ino=%lu}}",
579 next, d_backing_inode(next), d_backing_inode(next)->i_ino);
580
581 } else if (!d_can_lookup(next)) {
582 pr_err("inode %lu is not a directory\n",
583 d_backing_inode(next)->i_ino);
584 ret = -ENOBUFS;
585 goto error;
586 }
587
588 } else {
589 /* non-index objects start out life as files */
590 if (d_is_negative(next)) {
591 ret = cachefiles_has_space(cache, 1, 0);
592 if (ret < 0)
593 goto no_space_error;
594
595 path.dentry = dir;
596 ret = security_path_mknod(&path, next, S_IFREG, 0);
597 if (ret < 0)
598 goto create_error;
599 start = jiffies;
600 ret = vfs_create(d_inode(dir), next, S_IFREG, true);
601 cachefiles_hist(cachefiles_create_histogram, start);
602 trace_cachefiles_create(object, next, ret);
603 if (ret < 0)
604 goto create_error;
605
606 ASSERT(d_backing_inode(next));
607
608 _debug("create -> %p{%p{ino=%lu}}",
609 next, d_backing_inode(next), d_backing_inode(next)->i_ino);
610
611 } else if (!d_can_lookup(next) &&
612 !d_is_reg(next)
613 ) {
614 pr_err("inode %lu is not a file or directory\n",
615 d_backing_inode(next)->i_ino);
616 ret = -ENOBUFS;
617 goto error;
618 }
619 }
620
621 /* process the next component */
622 if (key) {
623 _debug("advance");
624 inode_unlock(d_inode(dir));
625 dput(dir);
626 dir = next;
627 next = NULL;
628 goto advance;
629 }
630
631 /* we've found the object we were looking for */
632 object->dentry = next;
633
634 /* if we've found that the terminal object exists, then we need to
635 * check its attributes and delete it if it's out of date */
636 if (!object->new) {
637 _debug("validate '%pd'", next);
638
639 ret = cachefiles_check_object_xattr(object, auxdata);
640 if (ret == -ESTALE) {
641 /* delete the object (the deleter drops the directory
642 * mutex) */
643 object->dentry = NULL;
644
645 ret = cachefiles_bury_object(cache, object, dir, next,
646 true,
647 FSCACHE_OBJECT_IS_STALE);
648 dput(next);
649 next = NULL;
650
651 if (ret < 0)
652 goto delete_error;
653
654 _debug("redo lookup");
655 fscache_object_retrying_stale(&object->fscache);
656 goto lookup_again;
657 }
658 }
659
660 /* note that we're now using this object */
661 ret = cachefiles_mark_object_active(cache, object);
662
663 inode_unlock(d_inode(dir));
664 dput(dir);
665 dir = NULL;
666
667 if (ret == -ETIMEDOUT)
668 goto mark_active_timed_out;
669
670 _debug("=== OBTAINED_OBJECT ===");
671
672 if (object->new) {
673 /* attach data to a newly constructed terminal object */
674 ret = cachefiles_set_object_xattr(object, auxdata);
675 if (ret < 0)
676 goto check_error;
677 } else {
678 /* always update the atime on an object we've just looked up
679 * (this is used to keep track of culling, and atimes are only
680 * updated by read, write and readdir but not lookup or
681 * open) */
682 path.dentry = next;
683 touch_atime(&path);
684 }
685
686 /* open a file interface onto a data file */
687 if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
688 if (d_is_reg(object->dentry)) {
689 const struct address_space_operations *aops;
690
691 ret = -EPERM;
692 aops = d_backing_inode(object->dentry)->i_mapping->a_ops;
693 if (!aops->bmap)
694 goto check_error;
695 if (object->dentry->d_sb->s_blocksize > PAGE_SIZE)
696 goto check_error;
697
698 object->backer = object->dentry;
699 } else {
700 BUG(); // TODO: open file in data-class subdir
701 }
702 }
703
704 object->new = 0;
705 fscache_obtained_object(&object->fscache);
706
707 _leave(" = 0 [%lu]", d_backing_inode(object->dentry)->i_ino);
708 return 0;
709
710no_space_error:
711 fscache_object_mark_killed(&object->fscache, FSCACHE_OBJECT_NO_SPACE);
712create_error:
713 _debug("create error %d", ret);
714 if (ret == -EIO)
715 cachefiles_io_error(cache, "Create/mkdir failed");
716 goto error;
717
718mark_active_timed_out:
719 _debug("mark active timed out");
720 goto release_dentry;
721
722check_error:
723 _debug("check error %d", ret);
724 cachefiles_mark_object_inactive(
725 cache, object, d_backing_inode(object->dentry)->i_blocks);
726release_dentry:
727 dput(object->dentry);
728 object->dentry = NULL;
729 goto error_out;
730
731delete_error:
732 _debug("delete error %d", ret);
733 goto error_out2;
734
735lookup_error:
736 _debug("lookup error %ld", PTR_ERR(next));
737 ret = PTR_ERR(next);
738 if (ret == -EIO)
739 cachefiles_io_error(cache, "Lookup failed");
740 next = NULL;
741error:
742 inode_unlock(d_inode(dir));
743 dput(next);
744error_out2:
745 dput(dir);
746error_out:
747 _leave(" = error %d", -ret);
748 return ret;
749}
750
751/*
752 * get a subdirectory
753 */
754struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
755 struct dentry *dir,
756 const char *dirname)
757{
758 struct dentry *subdir;
759 unsigned long start;
760 struct path path;
761 int ret;
762
763 _enter(",,%s", dirname);
764
765 /* search the current directory for the element name */
766 inode_lock(d_inode(dir));
767
768retry:
769 start = jiffies;
770 subdir = lookup_one_len(dirname, dir, strlen(dirname));
771 cachefiles_hist(cachefiles_lookup_histogram, start);
772 if (IS_ERR(subdir)) {
773 if (PTR_ERR(subdir) == -ENOMEM)
774 goto nomem_d_alloc;
775 goto lookup_error;
776 }
777
778 _debug("subdir -> %p %s",
779 subdir, d_backing_inode(subdir) ? "positive" : "negative");
780
781 /* we need to create the subdir if it doesn't exist yet */
782 if (d_is_negative(subdir)) {
783 ret = cachefiles_has_space(cache, 1, 0);
784 if (ret < 0)
785 goto mkdir_error;
786
787 _debug("attempt mkdir");
788
789 path.mnt = cache->mnt;
790 path.dentry = dir;
791 ret = security_path_mkdir(&path, subdir, 0700);
792 if (ret < 0)
793 goto mkdir_error;
794 ret = vfs_mkdir(d_inode(dir), subdir, 0700);
795 if (ret < 0)
796 goto mkdir_error;
797
798 if (unlikely(d_unhashed(subdir))) {
799 dput(subdir);
800 goto retry;
801 }
802 ASSERT(d_backing_inode(subdir));
803
804 _debug("mkdir -> %p{%p{ino=%lu}}",
805 subdir,
806 d_backing_inode(subdir),
807 d_backing_inode(subdir)->i_ino);
808 }
809
810 inode_unlock(d_inode(dir));
811
812 /* we need to make sure the subdir is a directory */
813 ASSERT(d_backing_inode(subdir));
814
815 if (!d_can_lookup(subdir)) {
816 pr_err("%s is not a directory\n", dirname);
817 ret = -EIO;
818 goto check_error;
819 }
820
821 ret = -EPERM;
822 if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) ||
823 !d_backing_inode(subdir)->i_op->lookup ||
824 !d_backing_inode(subdir)->i_op->mkdir ||
825 !d_backing_inode(subdir)->i_op->create ||
826 !d_backing_inode(subdir)->i_op->rename ||
827 !d_backing_inode(subdir)->i_op->rmdir ||
828 !d_backing_inode(subdir)->i_op->unlink)
829 goto check_error;
830
831 _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
832 return subdir;
833
834check_error:
835 dput(subdir);
836 _leave(" = %d [check]", ret);
837 return ERR_PTR(ret);
838
839mkdir_error:
840 inode_unlock(d_inode(dir));
841 dput(subdir);
842 pr_err("mkdir %s failed with error %d\n", dirname, ret);
843 return ERR_PTR(ret);
844
845lookup_error:
846 inode_unlock(d_inode(dir));
847 ret = PTR_ERR(subdir);
848 pr_err("Lookup %s failed with error %d\n", dirname, ret);
849 return ERR_PTR(ret);
850
851nomem_d_alloc:
852 inode_unlock(d_inode(dir));
853 _leave(" = -ENOMEM");
854 return ERR_PTR(-ENOMEM);
855}
856
857/*
858 * find out if an object is in use or not
859 * - if finds object and it's not in use:
860 * - returns a pointer to the object and a reference on it
861 * - returns with the directory locked
862 */
863static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
864 struct dentry *dir,
865 char *filename)
866{
867 struct cachefiles_object *object;
868 struct rb_node *_n;
869 struct dentry *victim;
870 unsigned long start;
871 int ret;
872
873 //_enter(",%pd/,%s",
874 // dir, filename);
875
876 /* look up the victim */
877 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
878
879 start = jiffies;
880 victim = lookup_one_len(filename, dir, strlen(filename));
881 cachefiles_hist(cachefiles_lookup_histogram, start);
882 if (IS_ERR(victim))
883 goto lookup_error;
884
885 //_debug("victim -> %p %s",
886 // victim, d_backing_inode(victim) ? "positive" : "negative");
887
888 /* if the object is no longer there then we probably retired the object
889 * at the netfs's request whilst the cull was in progress
890 */
891 if (d_is_negative(victim)) {
892 inode_unlock(d_inode(dir));
893 dput(victim);
894 _leave(" = -ENOENT [absent]");
895 return ERR_PTR(-ENOENT);
896 }
897
898 /* check to see if we're using this object */
899 read_lock(&cache->active_lock);
900
901 _n = cache->active_nodes.rb_node;
902
903 while (_n) {
904 object = rb_entry(_n, struct cachefiles_object, active_node);
905
906 if (object->dentry > victim)
907 _n = _n->rb_left;
908 else if (object->dentry < victim)
909 _n = _n->rb_right;
910 else
911 goto object_in_use;
912 }
913
914 read_unlock(&cache->active_lock);
915
916 //_leave(" = %p", victim);
917 return victim;
918
919object_in_use:
920 read_unlock(&cache->active_lock);
921 inode_unlock(d_inode(dir));
922 dput(victim);
923 //_leave(" = -EBUSY [in use]");
924 return ERR_PTR(-EBUSY);
925
926lookup_error:
927 inode_unlock(d_inode(dir));
928 ret = PTR_ERR(victim);
929 if (ret == -ENOENT) {
930 /* file or dir now absent - probably retired by netfs */
931 _leave(" = -ESTALE [absent]");
932 return ERR_PTR(-ESTALE);
933 }
934
935 if (ret == -EIO) {
936 cachefiles_io_error(cache, "Lookup failed");
937 } else if (ret != -ENOMEM) {
938 pr_err("Internal error: %d\n", ret);
939 ret = -EIO;
940 }
941
942 _leave(" = %d", ret);
943 return ERR_PTR(ret);
944}
945
946/*
947 * cull an object if it's not in use
948 * - called only by cache manager daemon
949 */
950int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
951 char *filename)
952{
953 struct dentry *victim;
954 int ret;
955
956 _enter(",%pd/,%s", dir, filename);
957
958 victim = cachefiles_check_active(cache, dir, filename);
959 if (IS_ERR(victim))
960 return PTR_ERR(victim);
961
962 _debug("victim -> %p %s",
963 victim, d_backing_inode(victim) ? "positive" : "negative");
964
965 /* okay... the victim is not being used so we can cull it
966 * - start by marking it as stale
967 */
968 _debug("victim is cullable");
969
970 ret = cachefiles_remove_object_xattr(cache, victim);
971 if (ret < 0)
972 goto error_unlock;
973
974 /* actually remove the victim (drops the dir mutex) */
975 _debug("bury");
976
977 ret = cachefiles_bury_object(cache, NULL, dir, victim, false,
978 FSCACHE_OBJECT_WAS_CULLED);
979 if (ret < 0)
980 goto error;
981
982 dput(victim);
983 _leave(" = 0");
984 return 0;
985
986error_unlock:
987 inode_unlock(d_inode(dir));
988error:
989 dput(victim);
990 if (ret == -ENOENT) {
991 /* file or dir now absent - probably retired by netfs */
992 _leave(" = -ESTALE [absent]");
993 return -ESTALE;
994 }
995
996 if (ret != -ENOMEM) {
997 pr_err("Internal error: %d\n", ret);
998 ret = -EIO;
999 }
1000
1001 _leave(" = %d", ret);
1002 return ret;
1003}
1004
1005/*
1006 * find out if an object is in use or not
1007 * - called only by cache manager daemon
1008 * - returns -EBUSY or 0 to indicate whether an object is in use or not
1009 */
1010int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
1011 char *filename)
1012{
1013 struct dentry *victim;
1014
1015 //_enter(",%pd/,%s",
1016 // dir, filename);
1017
1018 victim = cachefiles_check_active(cache, dir, filename);
1019 if (IS_ERR(victim))
1020 return PTR_ERR(victim);
1021
1022 inode_unlock(d_inode(dir));
1023 dput(victim);
1024 //_leave(" = 0");
1025 return 0;
1026}