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TOMOYO Linux Cross Reference
Linux/fs/cachefiles/namei.c

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  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 <linux/slab.h>
 23 #include <linux/xattr.h>
 24 #include "internal.h"
 25 
 26 #define CACHEFILES_KEYBUF_SIZE 512
 27 
 28 /*
 29  * dump debugging info about an object
 30  */
 31 static noinline
 32 void __cachefiles_printk_object(struct cachefiles_object *object,
 33                                 const char *prefix)
 34 {
 35         struct fscache_cookie *cookie;
 36         const u8 *k;
 37         unsigned loop;
 38 
 39         pr_err("%sobject: OBJ%x\n", prefix, object->fscache.debug_id);
 40         pr_err("%sobjstate=%s fl=%lx wbusy=%x ev=%lx[%lx]\n",
 41                prefix, object->fscache.state->name,
 42                object->fscache.flags, work_busy(&object->fscache.work),
 43                object->fscache.events, object->fscache.event_mask);
 44         pr_err("%sops=%u inp=%u exc=%u\n",
 45                prefix, object->fscache.n_ops, object->fscache.n_in_progress,
 46                object->fscache.n_exclusive);
 47         pr_err("%sparent=%p\n",
 48                prefix, object->fscache.parent);
 49 
 50         spin_lock(&object->fscache.lock);
 51         cookie = object->fscache.cookie;
 52         if (cookie) {
 53                 pr_err("%scookie=%p [pr=%p nd=%p fl=%lx]\n",
 54                        prefix,
 55                        object->fscache.cookie,
 56                        object->fscache.cookie->parent,
 57                        object->fscache.cookie->netfs_data,
 58                        object->fscache.cookie->flags);
 59                 pr_err("%skey=[%u] '", prefix, cookie->key_len);
 60                 k = (cookie->key_len <= sizeof(cookie->inline_key)) ?
 61                         cookie->inline_key : cookie->key;
 62                 for (loop = 0; loop < cookie->key_len; loop++)
 63                         pr_cont("%02x", k[loop]);
 64                 pr_cont("'\n");
 65         } else {
 66                 pr_err("%scookie=NULL\n", prefix);
 67         }
 68         spin_unlock(&object->fscache.lock);
 69 }
 70 
 71 /*
 72  * dump debugging info about a pair of objects
 73  */
 74 static noinline void cachefiles_printk_object(struct cachefiles_object *object,
 75                                               struct cachefiles_object *xobject)
 76 {
 77         if (object)
 78                 __cachefiles_printk_object(object, "");
 79         if (xobject)
 80                 __cachefiles_printk_object(xobject, "x");
 81 }
 82 
 83 /*
 84  * mark the owner of a dentry, if there is one, to indicate that that dentry
 85  * has been preemptively deleted
 86  * - the caller must hold the i_mutex on the dentry's parent as required to
 87  *   call vfs_unlink(), vfs_rmdir() or vfs_rename()
 88  */
 89 static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
 90                                           struct dentry *dentry,
 91                                           enum fscache_why_object_killed why)
 92 {
 93         struct cachefiles_object *object;
 94         struct rb_node *p;
 95 
 96         _enter(",'%pd'", dentry);
 97 
 98         write_lock(&cache->active_lock);
 99 
100         p = cache->active_nodes.rb_node;
101         while (p) {
102                 object = rb_entry(p, struct cachefiles_object, active_node);
103                 if (object->dentry > dentry)
104                         p = p->rb_left;
105                 else if (object->dentry < dentry)
106                         p = p->rb_right;
107                 else
108                         goto found_dentry;
109         }
110 
111         write_unlock(&cache->active_lock);
112         trace_cachefiles_mark_buried(NULL, dentry, why);
113         _leave(" [no owner]");
114         return;
115 
116         /* found the dentry for  */
117 found_dentry:
118         kdebug("preemptive burial: OBJ%x [%s] %p",
119                object->fscache.debug_id,
120                object->fscache.state->name,
121                dentry);
122 
123         trace_cachefiles_mark_buried(object, dentry, why);
124 
125         if (fscache_object_is_live(&object->fscache)) {
126                 pr_err("\n");
127                 pr_err("Error: Can't preemptively bury live object\n");
128                 cachefiles_printk_object(object, NULL);
129         } else {
130                 if (why != FSCACHE_OBJECT_IS_STALE)
131                         fscache_object_mark_killed(&object->fscache, why);
132         }
133 
134         write_unlock(&cache->active_lock);
135         _leave(" [owner marked]");
136 }
137 
138 /*
139  * record the fact that an object is now active
140  */
141 static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
142                                          struct cachefiles_object *object)
143 {
144         struct cachefiles_object *xobject;
145         struct rb_node **_p, *_parent = NULL;
146         struct dentry *dentry;
147 
148         _enter(",%p", object);
149 
150 try_again:
151         write_lock(&cache->active_lock);
152 
153         dentry = object->dentry;
154         trace_cachefiles_mark_active(object, dentry);
155 
156         if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
157                 pr_err("Error: Object already active\n");
158                 cachefiles_printk_object(object, NULL);
159                 BUG();
160         }
161 
162         _p = &cache->active_nodes.rb_node;
163         while (*_p) {
164                 _parent = *_p;
165                 xobject = rb_entry(_parent,
166                                    struct cachefiles_object, active_node);
167 
168                 ASSERT(xobject != object);
169 
170                 if (xobject->dentry > dentry)
171                         _p = &(*_p)->rb_left;
172                 else if (xobject->dentry < dentry)
173                         _p = &(*_p)->rb_right;
174                 else
175                         goto wait_for_old_object;
176         }
177 
178         rb_link_node(&object->active_node, _parent, _p);
179         rb_insert_color(&object->active_node, &cache->active_nodes);
180 
181         write_unlock(&cache->active_lock);
182         _leave(" = 0");
183         return 0;
184 
185         /* an old object from a previous incarnation is hogging the slot - we
186          * need to wait for it to be destroyed */
187 wait_for_old_object:
188         trace_cachefiles_wait_active(object, dentry, xobject);
189         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
190 
191         if (fscache_object_is_live(&xobject->fscache)) {
192                 pr_err("\n");
193                 pr_err("Error: Unexpected object collision\n");
194                 cachefiles_printk_object(object, xobject);
195         }
196         atomic_inc(&xobject->usage);
197         write_unlock(&cache->active_lock);
198 
199         if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
200                 wait_queue_head_t *wq;
201 
202                 signed long timeout = 60 * HZ;
203                 wait_queue_entry_t wait;
204                 bool requeue;
205 
206                 /* if the object we're waiting for is queued for processing,
207                  * then just put ourselves on the queue behind it */
208                 if (work_pending(&xobject->fscache.work)) {
209                         _debug("queue OBJ%x behind OBJ%x immediately",
210                                object->fscache.debug_id,
211                                xobject->fscache.debug_id);
212                         goto requeue;
213                 }
214 
215                 /* otherwise we sleep until either the object we're waiting for
216                  * is done, or the fscache_object is congested */
217                 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
218                 init_wait(&wait);
219                 requeue = false;
220                 do {
221                         prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
222                         if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
223                                 break;
224 
225                         requeue = fscache_object_sleep_till_congested(&timeout);
226                 } while (timeout > 0 && !requeue);
227                 finish_wait(wq, &wait);
228 
229                 if (requeue &&
230                     test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
231                         _debug("queue OBJ%x behind OBJ%x after wait",
232                                object->fscache.debug_id,
233                                xobject->fscache.debug_id);
234                         goto requeue;
235                 }
236 
237                 if (timeout <= 0) {
238                         pr_err("\n");
239                         pr_err("Error: Overlong wait for old active object to go away\n");
240                         cachefiles_printk_object(object, xobject);
241                         goto requeue;
242                 }
243         }
244 
245         ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
246 
247         cache->cache.ops->put_object(&xobject->fscache, cachefiles_obj_put_wait_retry);
248         goto try_again;
249 
250 requeue:
251         cache->cache.ops->put_object(&xobject->fscache, cachefiles_obj_put_wait_timeo);
252         _leave(" = -ETIMEDOUT");
253         return -ETIMEDOUT;
254 }
255 
256 /*
257  * Mark an object as being inactive.
258  */
259 void cachefiles_mark_object_inactive(struct cachefiles_cache *cache,
260                                      struct cachefiles_object *object,
261                                      blkcnt_t i_blocks)
262 {
263         struct dentry *dentry = object->dentry;
264         struct inode *inode = d_backing_inode(dentry);
265 
266         trace_cachefiles_mark_inactive(object, dentry, inode);
267 
268         write_lock(&cache->active_lock);
269         rb_erase(&object->active_node, &cache->active_nodes);
270         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
271         write_unlock(&cache->active_lock);
272 
273         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
274 
275         /* This object can now be culled, so we need to let the daemon know
276          * that there is something it can remove if it needs to.
277          */
278         atomic_long_add(i_blocks, &cache->b_released);
279         if (atomic_inc_return(&cache->f_released))
280                 cachefiles_state_changed(cache);
281 }
282 
283 /*
284  * delete an object representation from the cache
285  * - file backed objects are unlinked
286  * - directory backed objects are stuffed into the graveyard for userspace to
287  *   delete
288  * - unlocks the directory mutex
289  */
290 static int cachefiles_bury_object(struct cachefiles_cache *cache,
291                                   struct cachefiles_object *object,
292                                   struct dentry *dir,
293                                   struct dentry *rep,
294                                   bool preemptive,
295                                   enum fscache_why_object_killed why)
296 {
297         struct dentry *grave, *trap;
298         struct path path, path_to_graveyard;
299         char nbuffer[8 + 8 + 1];
300         int ret;
301 
302         _enter(",'%pd','%pd'", dir, rep);
303 
304         _debug("remove %p from %p", rep, dir);
305 
306         /* non-directories can just be unlinked */
307         if (!d_is_dir(rep)) {
308                 _debug("unlink stale object");
309 
310                 path.mnt = cache->mnt;
311                 path.dentry = dir;
312                 ret = security_path_unlink(&path, rep);
313                 if (ret < 0) {
314                         cachefiles_io_error(cache, "Unlink security error");
315                 } else {
316                         trace_cachefiles_unlink(object, rep, why);
317                         ret = vfs_unlink(d_inode(dir), rep, NULL);
318 
319                         if (preemptive)
320                                 cachefiles_mark_object_buried(cache, rep, why);
321                 }
322 
323                 inode_unlock(d_inode(dir));
324 
325                 if (ret == -EIO)
326                         cachefiles_io_error(cache, "Unlink failed");
327 
328                 _leave(" = %d", ret);
329                 return ret;
330         }
331 
332         /* directories have to be moved to the graveyard */
333         _debug("move stale object to graveyard");
334         inode_unlock(d_inode(dir));
335 
336 try_again:
337         /* first step is to make up a grave dentry in the graveyard */
338         sprintf(nbuffer, "%08x%08x",
339                 (uint32_t) get_seconds(),
340                 (uint32_t) atomic_inc_return(&cache->gravecounter));
341 
342         /* do the multiway lock magic */
343         trap = lock_rename(cache->graveyard, dir);
344 
345         /* do some checks before getting the grave dentry */
346         if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) {
347                 /* the entry was probably culled when we dropped the parent dir
348                  * lock */
349                 unlock_rename(cache->graveyard, dir);
350                 _leave(" = 0 [culled?]");
351                 return 0;
352         }
353 
354         if (!d_can_lookup(cache->graveyard)) {
355                 unlock_rename(cache->graveyard, dir);
356                 cachefiles_io_error(cache, "Graveyard no longer a directory");
357                 return -EIO;
358         }
359 
360         if (trap == rep) {
361                 unlock_rename(cache->graveyard, dir);
362                 cachefiles_io_error(cache, "May not make directory loop");
363                 return -EIO;
364         }
365 
366         if (d_mountpoint(rep)) {
367                 unlock_rename(cache->graveyard, dir);
368                 cachefiles_io_error(cache, "Mountpoint in cache");
369                 return -EIO;
370         }
371 
372         grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
373         if (IS_ERR(grave)) {
374                 unlock_rename(cache->graveyard, dir);
375 
376                 if (PTR_ERR(grave) == -ENOMEM) {
377                         _leave(" = -ENOMEM");
378                         return -ENOMEM;
379                 }
380 
381                 cachefiles_io_error(cache, "Lookup error %ld",
382                                     PTR_ERR(grave));
383                 return -EIO;
384         }
385 
386         if (d_is_positive(grave)) {
387                 unlock_rename(cache->graveyard, dir);
388                 dput(grave);
389                 grave = NULL;
390                 cond_resched();
391                 goto try_again;
392         }
393 
394         if (d_mountpoint(grave)) {
395                 unlock_rename(cache->graveyard, dir);
396                 dput(grave);
397                 cachefiles_io_error(cache, "Mountpoint in graveyard");
398                 return -EIO;
399         }
400 
401         /* target should not be an ancestor of source */
402         if (trap == grave) {
403                 unlock_rename(cache->graveyard, dir);
404                 dput(grave);
405                 cachefiles_io_error(cache, "May not make directory loop");
406                 return -EIO;
407         }
408 
409         /* attempt the rename */
410         path.mnt = cache->mnt;
411         path.dentry = dir;
412         path_to_graveyard.mnt = cache->mnt;
413         path_to_graveyard.dentry = cache->graveyard;
414         ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0);
415         if (ret < 0) {
416                 cachefiles_io_error(cache, "Rename security error %d", ret);
417         } else {
418                 trace_cachefiles_rename(object, rep, grave, why);
419                 ret = vfs_rename(d_inode(dir), rep,
420                                  d_inode(cache->graveyard), grave, NULL, 0);
421                 if (ret != 0 && ret != -ENOMEM)
422                         cachefiles_io_error(cache,
423                                             "Rename failed with error %d", ret);
424 
425                 if (preemptive)
426                         cachefiles_mark_object_buried(cache, rep, why);
427         }
428 
429         unlock_rename(cache->graveyard, dir);
430         dput(grave);
431         _leave(" = 0");
432         return 0;
433 }
434 
435 /*
436  * delete an object representation from the cache
437  */
438 int cachefiles_delete_object(struct cachefiles_cache *cache,
439                              struct cachefiles_object *object)
440 {
441         struct dentry *dir;
442         int ret;
443 
444         _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
445 
446         ASSERT(object->dentry);
447         ASSERT(d_backing_inode(object->dentry));
448         ASSERT(object->dentry->d_parent);
449 
450         dir = dget_parent(object->dentry);
451 
452         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
453 
454         if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
455                 /* object allocation for the same key preemptively deleted this
456                  * object's file so that it could create its own file */
457                 _debug("object preemptively buried");
458                 inode_unlock(d_inode(dir));
459                 ret = 0;
460         } else {
461                 /* we need to check that our parent is _still_ our parent - it
462                  * may have been renamed */
463                 if (dir == object->dentry->d_parent) {
464                         ret = cachefiles_bury_object(cache, object, dir,
465                                                      object->dentry, false,
466                                                      FSCACHE_OBJECT_WAS_RETIRED);
467                 } else {
468                         /* it got moved, presumably by cachefilesd culling it,
469                          * so it's no longer in the key path and we can ignore
470                          * it */
471                         inode_unlock(d_inode(dir));
472                         ret = 0;
473                 }
474         }
475 
476         dput(dir);
477         _leave(" = %d", ret);
478         return ret;
479 }
480 
481 /*
482  * walk from the parent object to the child object through the backing
483  * filesystem, creating directories as we go
484  */
485 int cachefiles_walk_to_object(struct cachefiles_object *parent,
486                               struct cachefiles_object *object,
487                               const char *key,
488                               struct cachefiles_xattr *auxdata)
489 {
490         struct cachefiles_cache *cache;
491         struct dentry *dir, *next = NULL;
492         struct inode *inode;
493         struct path path;
494         unsigned long start;
495         const char *name;
496         int ret, nlen;
497 
498         _enter("OBJ%x{%p},OBJ%x,%s,",
499                parent->fscache.debug_id, parent->dentry,
500                object->fscache.debug_id, key);
501 
502         cache = container_of(parent->fscache.cache,
503                              struct cachefiles_cache, cache);
504         path.mnt = cache->mnt;
505 
506         ASSERT(parent->dentry);
507         ASSERT(d_backing_inode(parent->dentry));
508 
509         if (!(d_is_dir(parent->dentry))) {
510                 // TODO: convert file to dir
511                 _leave("looking up in none directory");
512                 return -ENOBUFS;
513         }
514 
515         dir = dget(parent->dentry);
516 
517 advance:
518         /* attempt to transit the first directory component */
519         name = key;
520         nlen = strlen(key);
521 
522         /* key ends in a double NUL */
523         key = key + nlen + 1;
524         if (!*key)
525                 key = NULL;
526 
527 lookup_again:
528         /* search the current directory for the element name */
529         _debug("lookup '%s'", name);
530 
531         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
532 
533         start = jiffies;
534         next = lookup_one_len(name, dir, nlen);
535         cachefiles_hist(cachefiles_lookup_histogram, start);
536         if (IS_ERR(next)) {
537                 trace_cachefiles_lookup(object, next, NULL);
538                 goto lookup_error;
539         }
540 
541         inode = d_backing_inode(next);
542         trace_cachefiles_lookup(object, next, inode);
543         _debug("next -> %p %s", next, inode ? "positive" : "negative");
544 
545         if (!key)
546                 object->new = !inode;
547 
548         /* if this element of the path doesn't exist, then the lookup phase
549          * failed, and we can release any readers in the certain knowledge that
550          * there's nothing for them to actually read */
551         if (d_is_negative(next))
552                 fscache_object_lookup_negative(&object->fscache);
553 
554         /* we need to create the object if it's negative */
555         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
556                 /* index objects and intervening tree levels must be subdirs */
557                 if (d_is_negative(next)) {
558                         ret = cachefiles_has_space(cache, 1, 0);
559                         if (ret < 0)
560                                 goto no_space_error;
561 
562                         path.dentry = dir;
563                         ret = security_path_mkdir(&path, next, 0);
564                         if (ret < 0)
565                                 goto create_error;
566                         start = jiffies;
567                         ret = vfs_mkdir(d_inode(dir), next, 0);
568                         cachefiles_hist(cachefiles_mkdir_histogram, start);
569                         if (!key)
570                                 trace_cachefiles_mkdir(object, next, ret);
571                         if (ret < 0)
572                                 goto create_error;
573 
574                         if (unlikely(d_unhashed(next))) {
575                                 dput(next);
576                                 inode_unlock(d_inode(dir));
577                                 goto lookup_again;
578                         }
579                         ASSERT(d_backing_inode(next));
580 
581                         _debug("mkdir -> %p{%p{ino=%lu}}",
582                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
583 
584                 } else if (!d_can_lookup(next)) {
585                         pr_err("inode %lu is not a directory\n",
586                                d_backing_inode(next)->i_ino);
587                         ret = -ENOBUFS;
588                         goto error;
589                 }
590 
591         } else {
592                 /* non-index objects start out life as files */
593                 if (d_is_negative(next)) {
594                         ret = cachefiles_has_space(cache, 1, 0);
595                         if (ret < 0)
596                                 goto no_space_error;
597 
598                         path.dentry = dir;
599                         ret = security_path_mknod(&path, next, S_IFREG, 0);
600                         if (ret < 0)
601                                 goto create_error;
602                         start = jiffies;
603                         ret = vfs_create(d_inode(dir), next, S_IFREG, true);
604                         cachefiles_hist(cachefiles_create_histogram, start);
605                         trace_cachefiles_create(object, next, ret);
606                         if (ret < 0)
607                                 goto create_error;
608 
609                         ASSERT(d_backing_inode(next));
610 
611                         _debug("create -> %p{%p{ino=%lu}}",
612                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
613 
614                 } else if (!d_can_lookup(next) &&
615                            !d_is_reg(next)
616                            ) {
617                         pr_err("inode %lu is not a file or directory\n",
618                                d_backing_inode(next)->i_ino);
619                         ret = -ENOBUFS;
620                         goto error;
621                 }
622         }
623 
624         /* process the next component */
625         if (key) {
626                 _debug("advance");
627                 inode_unlock(d_inode(dir));
628                 dput(dir);
629                 dir = next;
630                 next = NULL;
631                 goto advance;
632         }
633 
634         /* we've found the object we were looking for */
635         object->dentry = next;
636 
637         /* if we've found that the terminal object exists, then we need to
638          * check its attributes and delete it if it's out of date */
639         if (!object->new) {
640                 _debug("validate '%pd'", next);
641 
642                 ret = cachefiles_check_object_xattr(object, auxdata);
643                 if (ret == -ESTALE) {
644                         /* delete the object (the deleter drops the directory
645                          * mutex) */
646                         object->dentry = NULL;
647 
648                         ret = cachefiles_bury_object(cache, object, dir, next,
649                                                      true,
650                                                      FSCACHE_OBJECT_IS_STALE);
651                         dput(next);
652                         next = NULL;
653 
654                         if (ret < 0)
655                                 goto delete_error;
656 
657                         _debug("redo lookup");
658                         fscache_object_retrying_stale(&object->fscache);
659                         goto lookup_again;
660                 }
661         }
662 
663         /* note that we're now using this object */
664         ret = cachefiles_mark_object_active(cache, object);
665 
666         inode_unlock(d_inode(dir));
667         dput(dir);
668         dir = NULL;
669 
670         if (ret == -ETIMEDOUT)
671                 goto mark_active_timed_out;
672 
673         _debug("=== OBTAINED_OBJECT ===");
674 
675         if (object->new) {
676                 /* attach data to a newly constructed terminal object */
677                 ret = cachefiles_set_object_xattr(object, auxdata);
678                 if (ret < 0)
679                         goto check_error;
680         } else {
681                 /* always update the atime on an object we've just looked up
682                  * (this is used to keep track of culling, and atimes are only
683                  * updated by read, write and readdir but not lookup or
684                  * open) */
685                 path.dentry = next;
686                 touch_atime(&path);
687         }
688 
689         /* open a file interface onto a data file */
690         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
691                 if (d_is_reg(object->dentry)) {
692                         const struct address_space_operations *aops;
693 
694                         ret = -EPERM;
695                         aops = d_backing_inode(object->dentry)->i_mapping->a_ops;
696                         if (!aops->bmap)
697                                 goto check_error;
698                         if (object->dentry->d_sb->s_blocksize > PAGE_SIZE)
699                                 goto check_error;
700 
701                         object->backer = object->dentry;
702                 } else {
703                         BUG(); // TODO: open file in data-class subdir
704                 }
705         }
706 
707         object->new = 0;
708         fscache_obtained_object(&object->fscache);
709 
710         _leave(" = 0 [%lu]", d_backing_inode(object->dentry)->i_ino);
711         return 0;
712 
713 no_space_error:
714         fscache_object_mark_killed(&object->fscache, FSCACHE_OBJECT_NO_SPACE);
715 create_error:
716         _debug("create error %d", ret);
717         if (ret == -EIO)
718                 cachefiles_io_error(cache, "Create/mkdir failed");
719         goto error;
720 
721 mark_active_timed_out:
722         _debug("mark active timed out");
723         goto release_dentry;
724 
725 check_error:
726         _debug("check error %d", ret);
727         cachefiles_mark_object_inactive(
728                 cache, object, d_backing_inode(object->dentry)->i_blocks);
729 release_dentry:
730         dput(object->dentry);
731         object->dentry = NULL;
732         goto error_out;
733 
734 delete_error:
735         _debug("delete error %d", ret);
736         goto error_out2;
737 
738 lookup_error:
739         _debug("lookup error %ld", PTR_ERR(next));
740         ret = PTR_ERR(next);
741         if (ret == -EIO)
742                 cachefiles_io_error(cache, "Lookup failed");
743         next = NULL;
744 error:
745         inode_unlock(d_inode(dir));
746         dput(next);
747 error_out2:
748         dput(dir);
749 error_out:
750         _leave(" = error %d", -ret);
751         return ret;
752 }
753 
754 /*
755  * get a subdirectory
756  */
757 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
758                                         struct dentry *dir,
759                                         const char *dirname)
760 {
761         struct dentry *subdir;
762         unsigned long start;
763         struct path path;
764         int ret;
765 
766         _enter(",,%s", dirname);
767 
768         /* search the current directory for the element name */
769         inode_lock(d_inode(dir));
770 
771 retry:
772         start = jiffies;
773         subdir = lookup_one_len(dirname, dir, strlen(dirname));
774         cachefiles_hist(cachefiles_lookup_histogram, start);
775         if (IS_ERR(subdir)) {
776                 if (PTR_ERR(subdir) == -ENOMEM)
777                         goto nomem_d_alloc;
778                 goto lookup_error;
779         }
780 
781         _debug("subdir -> %p %s",
782                subdir, d_backing_inode(subdir) ? "positive" : "negative");
783 
784         /* we need to create the subdir if it doesn't exist yet */
785         if (d_is_negative(subdir)) {
786                 ret = cachefiles_has_space(cache, 1, 0);
787                 if (ret < 0)
788                         goto mkdir_error;
789 
790                 _debug("attempt mkdir");
791 
792                 path.mnt = cache->mnt;
793                 path.dentry = dir;
794                 ret = security_path_mkdir(&path, subdir, 0700);
795                 if (ret < 0)
796                         goto mkdir_error;
797                 ret = vfs_mkdir(d_inode(dir), subdir, 0700);
798                 if (ret < 0)
799                         goto mkdir_error;
800 
801                 if (unlikely(d_unhashed(subdir))) {
802                         dput(subdir);
803                         goto retry;
804                 }
805                 ASSERT(d_backing_inode(subdir));
806 
807                 _debug("mkdir -> %p{%p{ino=%lu}}",
808                        subdir,
809                        d_backing_inode(subdir),
810                        d_backing_inode(subdir)->i_ino);
811         }
812 
813         inode_unlock(d_inode(dir));
814 
815         /* we need to make sure the subdir is a directory */
816         ASSERT(d_backing_inode(subdir));
817 
818         if (!d_can_lookup(subdir)) {
819                 pr_err("%s is not a directory\n", dirname);
820                 ret = -EIO;
821                 goto check_error;
822         }
823 
824         ret = -EPERM;
825         if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) ||
826             !d_backing_inode(subdir)->i_op->lookup ||
827             !d_backing_inode(subdir)->i_op->mkdir ||
828             !d_backing_inode(subdir)->i_op->create ||
829             !d_backing_inode(subdir)->i_op->rename ||
830             !d_backing_inode(subdir)->i_op->rmdir ||
831             !d_backing_inode(subdir)->i_op->unlink)
832                 goto check_error;
833 
834         _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
835         return subdir;
836 
837 check_error:
838         dput(subdir);
839         _leave(" = %d [check]", ret);
840         return ERR_PTR(ret);
841 
842 mkdir_error:
843         inode_unlock(d_inode(dir));
844         dput(subdir);
845         pr_err("mkdir %s failed with error %d\n", dirname, ret);
846         return ERR_PTR(ret);
847 
848 lookup_error:
849         inode_unlock(d_inode(dir));
850         ret = PTR_ERR(subdir);
851         pr_err("Lookup %s failed with error %d\n", dirname, ret);
852         return ERR_PTR(ret);
853 
854 nomem_d_alloc:
855         inode_unlock(d_inode(dir));
856         _leave(" = -ENOMEM");
857         return ERR_PTR(-ENOMEM);
858 }
859 
860 /*
861  * find out if an object is in use or not
862  * - if finds object and it's not in use:
863  *   - returns a pointer to the object and a reference on it
864  *   - returns with the directory locked
865  */
866 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
867                                               struct dentry *dir,
868                                               char *filename)
869 {
870         struct cachefiles_object *object;
871         struct rb_node *_n;
872         struct dentry *victim;
873         unsigned long start;
874         int ret;
875 
876         //_enter(",%pd/,%s",
877         //       dir, filename);
878 
879         /* look up the victim */
880         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
881 
882         start = jiffies;
883         victim = lookup_one_len(filename, dir, strlen(filename));
884         cachefiles_hist(cachefiles_lookup_histogram, start);
885         if (IS_ERR(victim))
886                 goto lookup_error;
887 
888         //_debug("victim -> %p %s",
889         //       victim, d_backing_inode(victim) ? "positive" : "negative");
890 
891         /* if the object is no longer there then we probably retired the object
892          * at the netfs's request whilst the cull was in progress
893          */
894         if (d_is_negative(victim)) {
895                 inode_unlock(d_inode(dir));
896                 dput(victim);
897                 _leave(" = -ENOENT [absent]");
898                 return ERR_PTR(-ENOENT);
899         }
900 
901         /* check to see if we're using this object */
902         read_lock(&cache->active_lock);
903 
904         _n = cache->active_nodes.rb_node;
905 
906         while (_n) {
907                 object = rb_entry(_n, struct cachefiles_object, active_node);
908 
909                 if (object->dentry > victim)
910                         _n = _n->rb_left;
911                 else if (object->dentry < victim)
912                         _n = _n->rb_right;
913                 else
914                         goto object_in_use;
915         }
916 
917         read_unlock(&cache->active_lock);
918 
919         //_leave(" = %p", victim);
920         return victim;
921 
922 object_in_use:
923         read_unlock(&cache->active_lock);
924         inode_unlock(d_inode(dir));
925         dput(victim);
926         //_leave(" = -EBUSY [in use]");
927         return ERR_PTR(-EBUSY);
928 
929 lookup_error:
930         inode_unlock(d_inode(dir));
931         ret = PTR_ERR(victim);
932         if (ret == -ENOENT) {
933                 /* file or dir now absent - probably retired by netfs */
934                 _leave(" = -ESTALE [absent]");
935                 return ERR_PTR(-ESTALE);
936         }
937 
938         if (ret == -EIO) {
939                 cachefiles_io_error(cache, "Lookup failed");
940         } else if (ret != -ENOMEM) {
941                 pr_err("Internal error: %d\n", ret);
942                 ret = -EIO;
943         }
944 
945         _leave(" = %d", ret);
946         return ERR_PTR(ret);
947 }
948 
949 /*
950  * cull an object if it's not in use
951  * - called only by cache manager daemon
952  */
953 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
954                     char *filename)
955 {
956         struct dentry *victim;
957         int ret;
958 
959         _enter(",%pd/,%s", dir, filename);
960 
961         victim = cachefiles_check_active(cache, dir, filename);
962         if (IS_ERR(victim))
963                 return PTR_ERR(victim);
964 
965         _debug("victim -> %p %s",
966                victim, d_backing_inode(victim) ? "positive" : "negative");
967 
968         /* okay... the victim is not being used so we can cull it
969          * - start by marking it as stale
970          */
971         _debug("victim is cullable");
972 
973         ret = cachefiles_remove_object_xattr(cache, victim);
974         if (ret < 0)
975                 goto error_unlock;
976 
977         /*  actually remove the victim (drops the dir mutex) */
978         _debug("bury");
979 
980         ret = cachefiles_bury_object(cache, NULL, dir, victim, false,
981                                      FSCACHE_OBJECT_WAS_CULLED);
982         if (ret < 0)
983                 goto error;
984 
985         dput(victim);
986         _leave(" = 0");
987         return 0;
988 
989 error_unlock:
990         inode_unlock(d_inode(dir));
991 error:
992         dput(victim);
993         if (ret == -ENOENT) {
994                 /* file or dir now absent - probably retired by netfs */
995                 _leave(" = -ESTALE [absent]");
996                 return -ESTALE;
997         }
998 
999         if (ret != -ENOMEM) {
1000                 pr_err("Internal error: %d\n", ret);
1001                 ret = -EIO;
1002         }
1003 
1004         _leave(" = %d", ret);
1005         return ret;
1006 }
1007 
1008 /*
1009  * find out if an object is in use or not
1010  * - called only by cache manager daemon
1011  * - returns -EBUSY or 0 to indicate whether an object is in use or not
1012  */
1013 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
1014                             char *filename)
1015 {
1016         struct dentry *victim;
1017 
1018         //_enter(",%pd/,%s",
1019         //       dir, filename);
1020 
1021         victim = cachefiles_check_active(cache, dir, filename);
1022         if (IS_ERR(victim))
1023                 return PTR_ERR(victim);
1024 
1025         inode_unlock(d_inode(dir));
1026         dput(victim);
1027         //_leave(" = 0");
1028         return 0;
1029 }
1030 

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