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9ae326a6 DH |
1 | /* CacheFiles path walking and related routines |
2 | * | |
3 | * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. | |
4 | * Written by David Howells (dhowells@redhat.com) | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public Licence | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the Licence, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #include <linux/module.h> | |
13 | #include <linux/sched.h> | |
14 | #include <linux/file.h> | |
15 | #include <linux/fs.h> | |
16 | #include <linux/fsnotify.h> | |
17 | #include <linux/quotaops.h> | |
18 | #include <linux/xattr.h> | |
19 | #include <linux/mount.h> | |
20 | #include <linux/namei.h> | |
21 | #include <linux/security.h> | |
22 | #include "internal.h" | |
23 | ||
24 | static int cachefiles_wait_bit(void *flags) | |
25 | { | |
26 | schedule(); | |
27 | return 0; | |
28 | } | |
29 | ||
30 | /* | |
31 | * record the fact that an object is now active | |
32 | */ | |
33 | static void cachefiles_mark_object_active(struct cachefiles_cache *cache, | |
34 | struct cachefiles_object *object) | |
35 | { | |
36 | struct cachefiles_object *xobject; | |
37 | struct rb_node **_p, *_parent = NULL; | |
38 | struct dentry *dentry; | |
39 | ||
40 | _enter(",%p", object); | |
41 | ||
42 | try_again: | |
43 | write_lock(&cache->active_lock); | |
44 | ||
45 | if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) | |
46 | BUG(); | |
47 | ||
48 | dentry = object->dentry; | |
49 | _p = &cache->active_nodes.rb_node; | |
50 | while (*_p) { | |
51 | _parent = *_p; | |
52 | xobject = rb_entry(_parent, | |
53 | struct cachefiles_object, active_node); | |
54 | ||
55 | ASSERT(xobject != object); | |
56 | ||
57 | if (xobject->dentry > dentry) | |
58 | _p = &(*_p)->rb_left; | |
59 | else if (xobject->dentry < dentry) | |
60 | _p = &(*_p)->rb_right; | |
61 | else | |
62 | goto wait_for_old_object; | |
63 | } | |
64 | ||
65 | rb_link_node(&object->active_node, _parent, _p); | |
66 | rb_insert_color(&object->active_node, &cache->active_nodes); | |
67 | ||
68 | write_unlock(&cache->active_lock); | |
69 | _leave(""); | |
70 | return; | |
71 | ||
72 | /* an old object from a previous incarnation is hogging the slot - we | |
73 | * need to wait for it to be destroyed */ | |
74 | wait_for_old_object: | |
75 | if (xobject->fscache.state < FSCACHE_OBJECT_DYING) { | |
76 | printk(KERN_ERR "\n"); | |
77 | printk(KERN_ERR "CacheFiles: Error:" | |
78 | " Unexpected object collision\n"); | |
79 | printk(KERN_ERR "xobject: OBJ%x\n", | |
80 | xobject->fscache.debug_id); | |
81 | printk(KERN_ERR "xobjstate=%s\n", | |
82 | fscache_object_states[xobject->fscache.state]); | |
83 | printk(KERN_ERR "xobjflags=%lx\n", xobject->fscache.flags); | |
84 | printk(KERN_ERR "xobjevent=%lx [%lx]\n", | |
85 | xobject->fscache.events, xobject->fscache.event_mask); | |
86 | printk(KERN_ERR "xops=%u inp=%u exc=%u\n", | |
87 | xobject->fscache.n_ops, xobject->fscache.n_in_progress, | |
88 | xobject->fscache.n_exclusive); | |
89 | printk(KERN_ERR "xcookie=%p [pr=%p nd=%p fl=%lx]\n", | |
90 | xobject->fscache.cookie, | |
91 | xobject->fscache.cookie->parent, | |
92 | xobject->fscache.cookie->netfs_data, | |
93 | xobject->fscache.cookie->flags); | |
94 | printk(KERN_ERR "xparent=%p\n", | |
95 | xobject->fscache.parent); | |
96 | printk(KERN_ERR "object: OBJ%x\n", | |
97 | object->fscache.debug_id); | |
98 | printk(KERN_ERR "cookie=%p [pr=%p nd=%p fl=%lx]\n", | |
99 | object->fscache.cookie, | |
100 | object->fscache.cookie->parent, | |
101 | object->fscache.cookie->netfs_data, | |
102 | object->fscache.cookie->flags); | |
103 | printk(KERN_ERR "parent=%p\n", | |
104 | object->fscache.parent); | |
105 | BUG(); | |
106 | } | |
107 | atomic_inc(&xobject->usage); | |
108 | write_unlock(&cache->active_lock); | |
109 | ||
110 | _debug(">>> wait"); | |
111 | wait_on_bit(&xobject->flags, CACHEFILES_OBJECT_ACTIVE, | |
112 | cachefiles_wait_bit, TASK_UNINTERRUPTIBLE); | |
113 | _debug("<<< waited"); | |
114 | ||
115 | cache->cache.ops->put_object(&xobject->fscache); | |
116 | goto try_again; | |
117 | } | |
118 | ||
119 | /* | |
120 | * delete an object representation from the cache | |
121 | * - file backed objects are unlinked | |
122 | * - directory backed objects are stuffed into the graveyard for userspace to | |
123 | * delete | |
124 | * - unlocks the directory mutex | |
125 | */ | |
126 | static int cachefiles_bury_object(struct cachefiles_cache *cache, | |
127 | struct dentry *dir, | |
128 | struct dentry *rep) | |
129 | { | |
130 | struct dentry *grave, *trap; | |
131 | char nbuffer[8 + 8 + 1]; | |
132 | int ret; | |
133 | ||
134 | _enter(",'%*.*s','%*.*s'", | |
135 | dir->d_name.len, dir->d_name.len, dir->d_name.name, | |
136 | rep->d_name.len, rep->d_name.len, rep->d_name.name); | |
137 | ||
138 | /* non-directories can just be unlinked */ | |
139 | if (!S_ISDIR(rep->d_inode->i_mode)) { | |
140 | _debug("unlink stale object"); | |
141 | ret = vfs_unlink(dir->d_inode, rep); | |
142 | ||
143 | mutex_unlock(&dir->d_inode->i_mutex); | |
144 | ||
145 | if (ret == -EIO) | |
146 | cachefiles_io_error(cache, "Unlink failed"); | |
147 | ||
148 | _leave(" = %d", ret); | |
149 | return ret; | |
150 | } | |
151 | ||
152 | /* directories have to be moved to the graveyard */ | |
153 | _debug("move stale object to graveyard"); | |
154 | mutex_unlock(&dir->d_inode->i_mutex); | |
155 | ||
156 | try_again: | |
157 | /* first step is to make up a grave dentry in the graveyard */ | |
158 | sprintf(nbuffer, "%08x%08x", | |
159 | (uint32_t) get_seconds(), | |
160 | (uint32_t) atomic_inc_return(&cache->gravecounter)); | |
161 | ||
162 | /* do the multiway lock magic */ | |
163 | trap = lock_rename(cache->graveyard, dir); | |
164 | ||
165 | /* do some checks before getting the grave dentry */ | |
166 | if (rep->d_parent != dir) { | |
167 | /* the entry was probably culled when we dropped the parent dir | |
168 | * lock */ | |
169 | unlock_rename(cache->graveyard, dir); | |
170 | _leave(" = 0 [culled?]"); | |
171 | return 0; | |
172 | } | |
173 | ||
174 | if (!S_ISDIR(cache->graveyard->d_inode->i_mode)) { | |
175 | unlock_rename(cache->graveyard, dir); | |
176 | cachefiles_io_error(cache, "Graveyard no longer a directory"); | |
177 | return -EIO; | |
178 | } | |
179 | ||
180 | if (trap == rep) { | |
181 | unlock_rename(cache->graveyard, dir); | |
182 | cachefiles_io_error(cache, "May not make directory loop"); | |
183 | return -EIO; | |
184 | } | |
185 | ||
186 | if (d_mountpoint(rep)) { | |
187 | unlock_rename(cache->graveyard, dir); | |
188 | cachefiles_io_error(cache, "Mountpoint in cache"); | |
189 | return -EIO; | |
190 | } | |
191 | ||
192 | grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer)); | |
193 | if (IS_ERR(grave)) { | |
194 | unlock_rename(cache->graveyard, dir); | |
195 | ||
196 | if (PTR_ERR(grave) == -ENOMEM) { | |
197 | _leave(" = -ENOMEM"); | |
198 | return -ENOMEM; | |
199 | } | |
200 | ||
201 | cachefiles_io_error(cache, "Lookup error %ld", | |
202 | PTR_ERR(grave)); | |
203 | return -EIO; | |
204 | } | |
205 | ||
206 | if (grave->d_inode) { | |
207 | unlock_rename(cache->graveyard, dir); | |
208 | dput(grave); | |
209 | grave = NULL; | |
210 | cond_resched(); | |
211 | goto try_again; | |
212 | } | |
213 | ||
214 | if (d_mountpoint(grave)) { | |
215 | unlock_rename(cache->graveyard, dir); | |
216 | dput(grave); | |
217 | cachefiles_io_error(cache, "Mountpoint in graveyard"); | |
218 | return -EIO; | |
219 | } | |
220 | ||
221 | /* target should not be an ancestor of source */ | |
222 | if (trap == grave) { | |
223 | unlock_rename(cache->graveyard, dir); | |
224 | dput(grave); | |
225 | cachefiles_io_error(cache, "May not make directory loop"); | |
226 | return -EIO; | |
227 | } | |
228 | ||
229 | /* attempt the rename */ | |
230 | ret = vfs_rename(dir->d_inode, rep, cache->graveyard->d_inode, grave); | |
231 | if (ret != 0 && ret != -ENOMEM) | |
232 | cachefiles_io_error(cache, "Rename failed with error %d", ret); | |
233 | ||
234 | unlock_rename(cache->graveyard, dir); | |
235 | dput(grave); | |
236 | _leave(" = 0"); | |
237 | return 0; | |
238 | } | |
239 | ||
240 | /* | |
241 | * delete an object representation from the cache | |
242 | */ | |
243 | int cachefiles_delete_object(struct cachefiles_cache *cache, | |
244 | struct cachefiles_object *object) | |
245 | { | |
246 | struct dentry *dir; | |
247 | int ret; | |
248 | ||
249 | _enter(",{%p}", object->dentry); | |
250 | ||
251 | ASSERT(object->dentry); | |
252 | ASSERT(object->dentry->d_inode); | |
253 | ASSERT(object->dentry->d_parent); | |
254 | ||
255 | dir = dget_parent(object->dentry); | |
256 | ||
257 | mutex_lock(&dir->d_inode->i_mutex); | |
258 | ret = cachefiles_bury_object(cache, dir, object->dentry); | |
259 | ||
260 | dput(dir); | |
261 | _leave(" = %d", ret); | |
262 | return ret; | |
263 | } | |
264 | ||
265 | /* | |
266 | * walk from the parent object to the child object through the backing | |
267 | * filesystem, creating directories as we go | |
268 | */ | |
269 | int cachefiles_walk_to_object(struct cachefiles_object *parent, | |
270 | struct cachefiles_object *object, | |
271 | const char *key, | |
272 | struct cachefiles_xattr *auxdata) | |
273 | { | |
274 | struct cachefiles_cache *cache; | |
275 | struct dentry *dir, *next = NULL; | |
276 | unsigned long start; | |
277 | const char *name; | |
278 | int ret, nlen; | |
279 | ||
280 | _enter("{%p},,%s,", parent->dentry, key); | |
281 | ||
282 | cache = container_of(parent->fscache.cache, | |
283 | struct cachefiles_cache, cache); | |
284 | ||
285 | ASSERT(parent->dentry); | |
286 | ASSERT(parent->dentry->d_inode); | |
287 | ||
288 | if (!(S_ISDIR(parent->dentry->d_inode->i_mode))) { | |
289 | // TODO: convert file to dir | |
290 | _leave("looking up in none directory"); | |
291 | return -ENOBUFS; | |
292 | } | |
293 | ||
294 | dir = dget(parent->dentry); | |
295 | ||
296 | advance: | |
297 | /* attempt to transit the first directory component */ | |
298 | name = key; | |
299 | nlen = strlen(key); | |
300 | ||
301 | /* key ends in a double NUL */ | |
302 | key = key + nlen + 1; | |
303 | if (!*key) | |
304 | key = NULL; | |
305 | ||
306 | lookup_again: | |
307 | /* search the current directory for the element name */ | |
308 | _debug("lookup '%s'", name); | |
309 | ||
310 | mutex_lock(&dir->d_inode->i_mutex); | |
311 | ||
312 | start = jiffies; | |
313 | next = lookup_one_len(name, dir, nlen); | |
314 | cachefiles_hist(cachefiles_lookup_histogram, start); | |
315 | if (IS_ERR(next)) | |
316 | goto lookup_error; | |
317 | ||
318 | _debug("next -> %p %s", next, next->d_inode ? "positive" : "negative"); | |
319 | ||
320 | if (!key) | |
321 | object->new = !next->d_inode; | |
322 | ||
323 | /* if this element of the path doesn't exist, then the lookup phase | |
324 | * failed, and we can release any readers in the certain knowledge that | |
325 | * there's nothing for them to actually read */ | |
326 | if (!next->d_inode) | |
327 | fscache_object_lookup_negative(&object->fscache); | |
328 | ||
329 | /* we need to create the object if it's negative */ | |
330 | if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) { | |
331 | /* index objects and intervening tree levels must be subdirs */ | |
332 | if (!next->d_inode) { | |
333 | ret = cachefiles_has_space(cache, 1, 0); | |
334 | if (ret < 0) | |
335 | goto create_error; | |
336 | ||
337 | start = jiffies; | |
338 | ret = vfs_mkdir(dir->d_inode, next, 0); | |
339 | cachefiles_hist(cachefiles_mkdir_histogram, start); | |
340 | if (ret < 0) | |
341 | goto create_error; | |
342 | ||
343 | ASSERT(next->d_inode); | |
344 | ||
345 | _debug("mkdir -> %p{%p{ino=%lu}}", | |
346 | next, next->d_inode, next->d_inode->i_ino); | |
347 | ||
348 | } else if (!S_ISDIR(next->d_inode->i_mode)) { | |
349 | kerror("inode %lu is not a directory", | |
350 | next->d_inode->i_ino); | |
351 | ret = -ENOBUFS; | |
352 | goto error; | |
353 | } | |
354 | ||
355 | } else { | |
356 | /* non-index objects start out life as files */ | |
357 | if (!next->d_inode) { | |
358 | ret = cachefiles_has_space(cache, 1, 0); | |
359 | if (ret < 0) | |
360 | goto create_error; | |
361 | ||
362 | start = jiffies; | |
363 | ret = vfs_create(dir->d_inode, next, S_IFREG, NULL); | |
364 | cachefiles_hist(cachefiles_create_histogram, start); | |
365 | if (ret < 0) | |
366 | goto create_error; | |
367 | ||
368 | ASSERT(next->d_inode); | |
369 | ||
370 | _debug("create -> %p{%p{ino=%lu}}", | |
371 | next, next->d_inode, next->d_inode->i_ino); | |
372 | ||
373 | } else if (!S_ISDIR(next->d_inode->i_mode) && | |
374 | !S_ISREG(next->d_inode->i_mode) | |
375 | ) { | |
376 | kerror("inode %lu is not a file or directory", | |
377 | next->d_inode->i_ino); | |
378 | ret = -ENOBUFS; | |
379 | goto error; | |
380 | } | |
381 | } | |
382 | ||
383 | /* process the next component */ | |
384 | if (key) { | |
385 | _debug("advance"); | |
386 | mutex_unlock(&dir->d_inode->i_mutex); | |
387 | dput(dir); | |
388 | dir = next; | |
389 | next = NULL; | |
390 | goto advance; | |
391 | } | |
392 | ||
393 | /* we've found the object we were looking for */ | |
394 | object->dentry = next; | |
395 | ||
396 | /* if we've found that the terminal object exists, then we need to | |
397 | * check its attributes and delete it if it's out of date */ | |
398 | if (!object->new) { | |
399 | _debug("validate '%*.*s'", | |
400 | next->d_name.len, next->d_name.len, next->d_name.name); | |
401 | ||
402 | ret = cachefiles_check_object_xattr(object, auxdata); | |
403 | if (ret == -ESTALE) { | |
404 | /* delete the object (the deleter drops the directory | |
405 | * mutex) */ | |
406 | object->dentry = NULL; | |
407 | ||
408 | ret = cachefiles_bury_object(cache, dir, next); | |
409 | dput(next); | |
410 | next = NULL; | |
411 | ||
412 | if (ret < 0) | |
413 | goto delete_error; | |
414 | ||
415 | _debug("redo lookup"); | |
416 | goto lookup_again; | |
417 | } | |
418 | } | |
419 | ||
420 | /* note that we're now using this object */ | |
421 | cachefiles_mark_object_active(cache, object); | |
422 | ||
423 | mutex_unlock(&dir->d_inode->i_mutex); | |
424 | dput(dir); | |
425 | dir = NULL; | |
426 | ||
427 | _debug("=== OBTAINED_OBJECT ==="); | |
428 | ||
429 | if (object->new) { | |
430 | /* attach data to a newly constructed terminal object */ | |
431 | ret = cachefiles_set_object_xattr(object, auxdata); | |
432 | if (ret < 0) | |
433 | goto check_error; | |
434 | } else { | |
435 | /* always update the atime on an object we've just looked up | |
436 | * (this is used to keep track of culling, and atimes are only | |
437 | * updated by read, write and readdir but not lookup or | |
438 | * open) */ | |
439 | touch_atime(cache->mnt, next); | |
440 | } | |
441 | ||
442 | /* open a file interface onto a data file */ | |
443 | if (object->type != FSCACHE_COOKIE_TYPE_INDEX) { | |
444 | if (S_ISREG(object->dentry->d_inode->i_mode)) { | |
445 | const struct address_space_operations *aops; | |
446 | ||
447 | ret = -EPERM; | |
448 | aops = object->dentry->d_inode->i_mapping->a_ops; | |
449 | if (!aops->bmap) | |
450 | goto check_error; | |
451 | ||
452 | object->backer = object->dentry; | |
453 | } else { | |
454 | BUG(); // TODO: open file in data-class subdir | |
455 | } | |
456 | } | |
457 | ||
458 | object->new = 0; | |
459 | fscache_obtained_object(&object->fscache); | |
460 | ||
461 | _leave(" = 0 [%lu]", object->dentry->d_inode->i_ino); | |
462 | return 0; | |
463 | ||
464 | create_error: | |
465 | _debug("create error %d", ret); | |
466 | if (ret == -EIO) | |
467 | cachefiles_io_error(cache, "Create/mkdir failed"); | |
468 | goto error; | |
469 | ||
470 | check_error: | |
471 | _debug("check error %d", ret); | |
472 | write_lock(&cache->active_lock); | |
473 | rb_erase(&object->active_node, &cache->active_nodes); | |
474 | clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags); | |
475 | wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE); | |
476 | write_unlock(&cache->active_lock); | |
477 | ||
478 | dput(object->dentry); | |
479 | object->dentry = NULL; | |
480 | goto error_out; | |
481 | ||
482 | delete_error: | |
483 | _debug("delete error %d", ret); | |
484 | goto error_out2; | |
485 | ||
486 | lookup_error: | |
487 | _debug("lookup error %ld", PTR_ERR(next)); | |
488 | ret = PTR_ERR(next); | |
489 | if (ret == -EIO) | |
490 | cachefiles_io_error(cache, "Lookup failed"); | |
491 | next = NULL; | |
492 | error: | |
493 | mutex_unlock(&dir->d_inode->i_mutex); | |
494 | dput(next); | |
495 | error_out2: | |
496 | dput(dir); | |
497 | error_out: | |
498 | if (ret == -ENOSPC) | |
499 | ret = -ENOBUFS; | |
500 | ||
501 | _leave(" = error %d", -ret); | |
502 | return ret; | |
503 | } | |
504 | ||
505 | /* | |
506 | * get a subdirectory | |
507 | */ | |
508 | struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache, | |
509 | struct dentry *dir, | |
510 | const char *dirname) | |
511 | { | |
512 | struct dentry *subdir; | |
513 | unsigned long start; | |
514 | int ret; | |
515 | ||
516 | _enter(",,%s", dirname); | |
517 | ||
518 | /* search the current directory for the element name */ | |
519 | mutex_lock(&dir->d_inode->i_mutex); | |
520 | ||
521 | start = jiffies; | |
522 | subdir = lookup_one_len(dirname, dir, strlen(dirname)); | |
523 | cachefiles_hist(cachefiles_lookup_histogram, start); | |
524 | if (IS_ERR(subdir)) { | |
525 | if (PTR_ERR(subdir) == -ENOMEM) | |
526 | goto nomem_d_alloc; | |
527 | goto lookup_error; | |
528 | } | |
529 | ||
530 | _debug("subdir -> %p %s", | |
531 | subdir, subdir->d_inode ? "positive" : "negative"); | |
532 | ||
533 | /* we need to create the subdir if it doesn't exist yet */ | |
534 | if (!subdir->d_inode) { | |
535 | ret = cachefiles_has_space(cache, 1, 0); | |
536 | if (ret < 0) | |
537 | goto mkdir_error; | |
538 | ||
539 | _debug("attempt mkdir"); | |
540 | ||
541 | ret = vfs_mkdir(dir->d_inode, subdir, 0700); | |
542 | if (ret < 0) | |
543 | goto mkdir_error; | |
544 | ||
545 | ASSERT(subdir->d_inode); | |
546 | ||
547 | _debug("mkdir -> %p{%p{ino=%lu}}", | |
548 | subdir, | |
549 | subdir->d_inode, | |
550 | subdir->d_inode->i_ino); | |
551 | } | |
552 | ||
553 | mutex_unlock(&dir->d_inode->i_mutex); | |
554 | ||
555 | /* we need to make sure the subdir is a directory */ | |
556 | ASSERT(subdir->d_inode); | |
557 | ||
558 | if (!S_ISDIR(subdir->d_inode->i_mode)) { | |
559 | kerror("%s is not a directory", dirname); | |
560 | ret = -EIO; | |
561 | goto check_error; | |
562 | } | |
563 | ||
564 | ret = -EPERM; | |
565 | if (!subdir->d_inode->i_op || | |
566 | !subdir->d_inode->i_op->setxattr || | |
567 | !subdir->d_inode->i_op->getxattr || | |
568 | !subdir->d_inode->i_op->lookup || | |
569 | !subdir->d_inode->i_op->mkdir || | |
570 | !subdir->d_inode->i_op->create || | |
571 | !subdir->d_inode->i_op->rename || | |
572 | !subdir->d_inode->i_op->rmdir || | |
573 | !subdir->d_inode->i_op->unlink) | |
574 | goto check_error; | |
575 | ||
576 | _leave(" = [%lu]", subdir->d_inode->i_ino); | |
577 | return subdir; | |
578 | ||
579 | check_error: | |
580 | dput(subdir); | |
581 | _leave(" = %d [check]", ret); | |
582 | return ERR_PTR(ret); | |
583 | ||
584 | mkdir_error: | |
585 | mutex_unlock(&dir->d_inode->i_mutex); | |
586 | dput(subdir); | |
587 | kerror("mkdir %s failed with error %d", dirname, ret); | |
588 | return ERR_PTR(ret); | |
589 | ||
590 | lookup_error: | |
591 | mutex_unlock(&dir->d_inode->i_mutex); | |
592 | ret = PTR_ERR(subdir); | |
593 | kerror("Lookup %s failed with error %d", dirname, ret); | |
594 | return ERR_PTR(ret); | |
595 | ||
596 | nomem_d_alloc: | |
597 | mutex_unlock(&dir->d_inode->i_mutex); | |
598 | _leave(" = -ENOMEM"); | |
599 | return ERR_PTR(-ENOMEM); | |
600 | } | |
601 | ||
602 | /* | |
603 | * find out if an object is in use or not | |
604 | * - if finds object and it's not in use: | |
605 | * - returns a pointer to the object and a reference on it | |
606 | * - returns with the directory locked | |
607 | */ | |
608 | static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache, | |
609 | struct dentry *dir, | |
610 | char *filename) | |
611 | { | |
612 | struct cachefiles_object *object; | |
613 | struct rb_node *_n; | |
614 | struct dentry *victim; | |
615 | unsigned long start; | |
616 | int ret; | |
617 | ||
618 | //_enter(",%*.*s/,%s", | |
619 | // dir->d_name.len, dir->d_name.len, dir->d_name.name, filename); | |
620 | ||
621 | /* look up the victim */ | |
622 | mutex_lock_nested(&dir->d_inode->i_mutex, 1); | |
623 | ||
624 | start = jiffies; | |
625 | victim = lookup_one_len(filename, dir, strlen(filename)); | |
626 | cachefiles_hist(cachefiles_lookup_histogram, start); | |
627 | if (IS_ERR(victim)) | |
628 | goto lookup_error; | |
629 | ||
630 | //_debug("victim -> %p %s", | |
631 | // victim, victim->d_inode ? "positive" : "negative"); | |
632 | ||
633 | /* if the object is no longer there then we probably retired the object | |
634 | * at the netfs's request whilst the cull was in progress | |
635 | */ | |
636 | if (!victim->d_inode) { | |
637 | mutex_unlock(&dir->d_inode->i_mutex); | |
638 | dput(victim); | |
639 | _leave(" = -ENOENT [absent]"); | |
640 | return ERR_PTR(-ENOENT); | |
641 | } | |
642 | ||
643 | /* check to see if we're using this object */ | |
644 | read_lock(&cache->active_lock); | |
645 | ||
646 | _n = cache->active_nodes.rb_node; | |
647 | ||
648 | while (_n) { | |
649 | object = rb_entry(_n, struct cachefiles_object, active_node); | |
650 | ||
651 | if (object->dentry > victim) | |
652 | _n = _n->rb_left; | |
653 | else if (object->dentry < victim) | |
654 | _n = _n->rb_right; | |
655 | else | |
656 | goto object_in_use; | |
657 | } | |
658 | ||
659 | read_unlock(&cache->active_lock); | |
660 | ||
661 | //_leave(" = %p", victim); | |
662 | return victim; | |
663 | ||
664 | object_in_use: | |
665 | read_unlock(&cache->active_lock); | |
666 | mutex_unlock(&dir->d_inode->i_mutex); | |
667 | dput(victim); | |
668 | //_leave(" = -EBUSY [in use]"); | |
669 | return ERR_PTR(-EBUSY); | |
670 | ||
671 | lookup_error: | |
672 | mutex_unlock(&dir->d_inode->i_mutex); | |
673 | ret = PTR_ERR(victim); | |
674 | if (ret == -ENOENT) { | |
675 | /* file or dir now absent - probably retired by netfs */ | |
676 | _leave(" = -ESTALE [absent]"); | |
677 | return ERR_PTR(-ESTALE); | |
678 | } | |
679 | ||
680 | if (ret == -EIO) { | |
681 | cachefiles_io_error(cache, "Lookup failed"); | |
682 | } else if (ret != -ENOMEM) { | |
683 | kerror("Internal error: %d", ret); | |
684 | ret = -EIO; | |
685 | } | |
686 | ||
687 | _leave(" = %d", ret); | |
688 | return ERR_PTR(ret); | |
689 | } | |
690 | ||
691 | /* | |
692 | * cull an object if it's not in use | |
693 | * - called only by cache manager daemon | |
694 | */ | |
695 | int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir, | |
696 | char *filename) | |
697 | { | |
698 | struct dentry *victim; | |
699 | int ret; | |
700 | ||
701 | _enter(",%*.*s/,%s", | |
702 | dir->d_name.len, dir->d_name.len, dir->d_name.name, filename); | |
703 | ||
704 | victim = cachefiles_check_active(cache, dir, filename); | |
705 | if (IS_ERR(victim)) | |
706 | return PTR_ERR(victim); | |
707 | ||
708 | _debug("victim -> %p %s", | |
709 | victim, victim->d_inode ? "positive" : "negative"); | |
710 | ||
711 | /* okay... the victim is not being used so we can cull it | |
712 | * - start by marking it as stale | |
713 | */ | |
714 | _debug("victim is cullable"); | |
715 | ||
716 | ret = cachefiles_remove_object_xattr(cache, victim); | |
717 | if (ret < 0) | |
718 | goto error_unlock; | |
719 | ||
720 | /* actually remove the victim (drops the dir mutex) */ | |
721 | _debug("bury"); | |
722 | ||
723 | ret = cachefiles_bury_object(cache, dir, victim); | |
724 | if (ret < 0) | |
725 | goto error; | |
726 | ||
727 | dput(victim); | |
728 | _leave(" = 0"); | |
729 | return 0; | |
730 | ||
731 | error_unlock: | |
732 | mutex_unlock(&dir->d_inode->i_mutex); | |
733 | error: | |
734 | dput(victim); | |
735 | if (ret == -ENOENT) { | |
736 | /* file or dir now absent - probably retired by netfs */ | |
737 | _leave(" = -ESTALE [absent]"); | |
738 | return -ESTALE; | |
739 | } | |
740 | ||
741 | if (ret != -ENOMEM) { | |
742 | kerror("Internal error: %d", ret); | |
743 | ret = -EIO; | |
744 | } | |
745 | ||
746 | _leave(" = %d", ret); | |
747 | return ret; | |
748 | } | |
749 | ||
750 | /* | |
751 | * find out if an object is in use or not | |
752 | * - called only by cache manager daemon | |
753 | * - returns -EBUSY or 0 to indicate whether an object is in use or not | |
754 | */ | |
755 | int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir, | |
756 | char *filename) | |
757 | { | |
758 | struct dentry *victim; | |
759 | ||
760 | //_enter(",%*.*s/,%s", | |
761 | // dir->d_name.len, dir->d_name.len, dir->d_name.name, filename); | |
762 | ||
763 | victim = cachefiles_check_active(cache, dir, filename); | |
764 | if (IS_ERR(victim)) | |
765 | return PTR_ERR(victim); | |
766 | ||
767 | mutex_unlock(&dir->d_inode->i_mutex); | |
768 | dput(victim); | |
769 | //_leave(" = 0"); | |
770 | return 0; | |
771 | } |