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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,
248                 (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_retry);
249         goto try_again;
250 
251 requeue:
252         cache->cache.ops->put_object(&xobject->fscache,
253                 (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_timeo);
254         _leave(" = -ETIMEDOUT");
255         return -ETIMEDOUT;
256 }
257 
258 /*
259  * Mark an object as being inactive.
260  */
261 void cachefiles_mark_object_inactive(struct cachefiles_cache *cache,
262                                      struct cachefiles_object *object,
263                                      blkcnt_t i_blocks)
264 {
265         struct dentry *dentry = object->dentry;
266         struct inode *inode = d_backing_inode(dentry);
267 
268         trace_cachefiles_mark_inactive(object, dentry, inode);
269 
270         write_lock(&cache->active_lock);
271         rb_erase(&object->active_node, &cache->active_nodes);
272         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
273         write_unlock(&cache->active_lock);
274 
275         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
276 
277         /* This object can now be culled, so we need to let the daemon know
278          * that there is something it can remove if it needs to.
279          */
280         atomic_long_add(i_blocks, &cache->b_released);
281         if (atomic_inc_return(&cache->f_released))
282                 cachefiles_state_changed(cache);
283 }
284 
285 /*
286  * delete an object representation from the cache
287  * - file backed objects are unlinked
288  * - directory backed objects are stuffed into the graveyard for userspace to
289  *   delete
290  * - unlocks the directory mutex
291  */
292 static int cachefiles_bury_object(struct cachefiles_cache *cache,
293                                   struct cachefiles_object *object,
294                                   struct dentry *dir,
295                                   struct dentry *rep,
296                                   bool preemptive,
297                                   enum fscache_why_object_killed why)
298 {
299         struct dentry *grave, *trap;
300         struct path path, path_to_graveyard;
301         char nbuffer[8 + 8 + 1];
302         int ret;
303 
304         _enter(",'%pd','%pd'", dir, rep);
305 
306         _debug("remove %p from %p", rep, dir);
307 
308         /* non-directories can just be unlinked */
309         if (!d_is_dir(rep)) {
310                 _debug("unlink stale object");
311 
312                 path.mnt = cache->mnt;
313                 path.dentry = dir;
314                 ret = security_path_unlink(&path, rep);
315                 if (ret < 0) {
316                         cachefiles_io_error(cache, "Unlink security error");
317                 } else {
318                         trace_cachefiles_unlink(object, rep, why);
319                         ret = vfs_unlink(d_inode(dir), rep, NULL);
320 
321                         if (preemptive)
322                                 cachefiles_mark_object_buried(cache, rep, why);
323                 }
324 
325                 inode_unlock(d_inode(dir));
326 
327                 if (ret == -EIO)
328                         cachefiles_io_error(cache, "Unlink failed");
329 
330                 _leave(" = %d", ret);
331                 return ret;
332         }
333 
334         /* directories have to be moved to the graveyard */
335         _debug("move stale object to graveyard");
336         inode_unlock(d_inode(dir));
337 
338 try_again:
339         /* first step is to make up a grave dentry in the graveyard */
340         sprintf(nbuffer, "%08x%08x",
341                 (uint32_t) ktime_get_real_seconds(),
342                 (uint32_t) atomic_inc_return(&cache->gravecounter));
343 
344         /* do the multiway lock magic */
345         trap = lock_rename(cache->graveyard, dir);
346 
347         /* do some checks before getting the grave dentry */
348         if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) {
349                 /* the entry was probably culled when we dropped the parent dir
350                  * lock */
351                 unlock_rename(cache->graveyard, dir);
352                 _leave(" = 0 [culled?]");
353                 return 0;
354         }
355 
356         if (!d_can_lookup(cache->graveyard)) {
357                 unlock_rename(cache->graveyard, dir);
358                 cachefiles_io_error(cache, "Graveyard no longer a directory");
359                 return -EIO;
360         }
361 
362         if (trap == rep) {
363                 unlock_rename(cache->graveyard, dir);
364                 cachefiles_io_error(cache, "May not make directory loop");
365                 return -EIO;
366         }
367 
368         if (d_mountpoint(rep)) {
369                 unlock_rename(cache->graveyard, dir);
370                 cachefiles_io_error(cache, "Mountpoint in cache");
371                 return -EIO;
372         }
373 
374         grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
375         if (IS_ERR(grave)) {
376                 unlock_rename(cache->graveyard, dir);
377 
378                 if (PTR_ERR(grave) == -ENOMEM) {
379                         _leave(" = -ENOMEM");
380                         return -ENOMEM;
381                 }
382 
383                 cachefiles_io_error(cache, "Lookup error %ld",
384                                     PTR_ERR(grave));
385                 return -EIO;
386         }
387 
388         if (d_is_positive(grave)) {
389                 unlock_rename(cache->graveyard, dir);
390                 dput(grave);
391                 grave = NULL;
392                 cond_resched();
393                 goto try_again;
394         }
395 
396         if (d_mountpoint(grave)) {
397                 unlock_rename(cache->graveyard, dir);
398                 dput(grave);
399                 cachefiles_io_error(cache, "Mountpoint in graveyard");
400                 return -EIO;
401         }
402 
403         /* target should not be an ancestor of source */
404         if (trap == grave) {
405                 unlock_rename(cache->graveyard, dir);
406                 dput(grave);
407                 cachefiles_io_error(cache, "May not make directory loop");
408                 return -EIO;
409         }
410 
411         /* attempt the rename */
412         path.mnt = cache->mnt;
413         path.dentry = dir;
414         path_to_graveyard.mnt = cache->mnt;
415         path_to_graveyard.dentry = cache->graveyard;
416         ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0);
417         if (ret < 0) {
418                 cachefiles_io_error(cache, "Rename security error %d", ret);
419         } else {
420                 trace_cachefiles_rename(object, rep, grave, why);
421                 ret = vfs_rename(d_inode(dir), rep,
422                                  d_inode(cache->graveyard), grave, NULL, 0);
423                 if (ret != 0 && ret != -ENOMEM)
424                         cachefiles_io_error(cache,
425                                             "Rename failed with error %d", ret);
426 
427                 if (preemptive)
428                         cachefiles_mark_object_buried(cache, rep, why);
429         }
430 
431         unlock_rename(cache->graveyard, dir);
432         dput(grave);
433         _leave(" = 0");
434         return 0;
435 }
436 
437 /*
438  * delete an object representation from the cache
439  */
440 int cachefiles_delete_object(struct cachefiles_cache *cache,
441                              struct cachefiles_object *object)
442 {
443         struct dentry *dir;
444         int ret;
445 
446         _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
447 
448         ASSERT(object->dentry);
449         ASSERT(d_backing_inode(object->dentry));
450         ASSERT(object->dentry->d_parent);
451 
452         dir = dget_parent(object->dentry);
453 
454         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
455 
456         if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
457                 /* object allocation for the same key preemptively deleted this
458                  * object's file so that it could create its own file */
459                 _debug("object preemptively buried");
460                 inode_unlock(d_inode(dir));
461                 ret = 0;
462         } else {
463                 /* we need to check that our parent is _still_ our parent - it
464                  * may have been renamed */
465                 if (dir == object->dentry->d_parent) {
466                         ret = cachefiles_bury_object(cache, object, dir,
467                                                      object->dentry, false,
468                                                      FSCACHE_OBJECT_WAS_RETIRED);
469                 } else {
470                         /* it got moved, presumably by cachefilesd culling it,
471                          * so it's no longer in the key path and we can ignore
472                          * it */
473                         inode_unlock(d_inode(dir));
474                         ret = 0;
475                 }
476         }
477 
478         dput(dir);
479         _leave(" = %d", ret);
480         return ret;
481 }
482 
483 /*
484  * walk from the parent object to the child object through the backing
485  * filesystem, creating directories as we go
486  */
487 int cachefiles_walk_to_object(struct cachefiles_object *parent,
488                               struct cachefiles_object *object,
489                               const char *key,
490                               struct cachefiles_xattr *auxdata)
491 {
492         struct cachefiles_cache *cache;
493         struct dentry *dir, *next = NULL;
494         struct inode *inode;
495         struct path path;
496         unsigned long start;
497         const char *name;
498         int ret, nlen;
499 
500         _enter("OBJ%x{%p},OBJ%x,%s,",
501                parent->fscache.debug_id, parent->dentry,
502                object->fscache.debug_id, key);
503 
504         cache = container_of(parent->fscache.cache,
505                              struct cachefiles_cache, cache);
506         path.mnt = cache->mnt;
507 
508         ASSERT(parent->dentry);
509         ASSERT(d_backing_inode(parent->dentry));
510 
511         if (!(d_is_dir(parent->dentry))) {
512                 // TODO: convert file to dir
513                 _leave("looking up in none directory");
514                 return -ENOBUFS;
515         }
516 
517         dir = dget(parent->dentry);
518 
519 advance:
520         /* attempt to transit the first directory component */
521         name = key;
522         nlen = strlen(key);
523 
524         /* key ends in a double NUL */
525         key = key + nlen + 1;
526         if (!*key)
527                 key = NULL;
528 
529 lookup_again:
530         /* search the current directory for the element name */
531         _debug("lookup '%s'", name);
532 
533         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
534 
535         start = jiffies;
536         next = lookup_one_len(name, dir, nlen);
537         cachefiles_hist(cachefiles_lookup_histogram, start);
538         if (IS_ERR(next)) {
539                 trace_cachefiles_lookup(object, next, NULL);
540                 goto lookup_error;
541         }
542 
543         inode = d_backing_inode(next);
544         trace_cachefiles_lookup(object, next, inode);
545         _debug("next -> %p %s", next, inode ? "positive" : "negative");
546 
547         if (!key)
548                 object->new = !inode;
549 
550         /* if this element of the path doesn't exist, then the lookup phase
551          * failed, and we can release any readers in the certain knowledge that
552          * there's nothing for them to actually read */
553         if (d_is_negative(next))
554                 fscache_object_lookup_negative(&object->fscache);
555 
556         /* we need to create the object if it's negative */
557         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
558                 /* index objects and intervening tree levels must be subdirs */
559                 if (d_is_negative(next)) {
560                         ret = cachefiles_has_space(cache, 1, 0);
561                         if (ret < 0)
562                                 goto no_space_error;
563 
564                         path.dentry = dir;
565                         ret = security_path_mkdir(&path, next, 0);
566                         if (ret < 0)
567                                 goto create_error;
568                         start = jiffies;
569                         ret = vfs_mkdir(d_inode(dir), next, 0);
570                         cachefiles_hist(cachefiles_mkdir_histogram, start);
571                         if (!key)
572                                 trace_cachefiles_mkdir(object, next, ret);
573                         if (ret < 0)
574                                 goto create_error;
575 
576                         if (unlikely(d_unhashed(next))) {
577                                 dput(next);
578                                 inode_unlock(d_inode(dir));
579                                 goto lookup_again;
580                         }
581                         ASSERT(d_backing_inode(next));
582 
583                         _debug("mkdir -> %p{%p{ino=%lu}}",
584                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
585 
586                 } else if (!d_can_lookup(next)) {
587                         pr_err("inode %lu is not a directory\n",
588                                d_backing_inode(next)->i_ino);
589                         ret = -ENOBUFS;
590                         goto error;
591                 }
592 
593         } else {
594                 /* non-index objects start out life as files */
595                 if (d_is_negative(next)) {
596                         ret = cachefiles_has_space(cache, 1, 0);
597                         if (ret < 0)
598                                 goto no_space_error;
599 
600                         path.dentry = dir;
601                         ret = security_path_mknod(&path, next, S_IFREG, 0);
602                         if (ret < 0)
603                                 goto create_error;
604                         start = jiffies;
605                         ret = vfs_create(d_inode(dir), next, S_IFREG, true);
606                         cachefiles_hist(cachefiles_create_histogram, start);
607                         trace_cachefiles_create(object, next, ret);
608                         if (ret < 0)
609                                 goto create_error;
610 
611                         ASSERT(d_backing_inode(next));
612 
613                         _debug("create -> %p{%p{ino=%lu}}",
614                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
615 
616                 } else if (!d_can_lookup(next) &&
617                            !d_is_reg(next)
618                            ) {
619                         pr_err("inode %lu is not a file or directory\n",
620                                d_backing_inode(next)->i_ino);
621                         ret = -ENOBUFS;
622                         goto error;
623                 }
624         }
625 
626         /* process the next component */
627         if (key) {
628                 _debug("advance");
629                 inode_unlock(d_inode(dir));
630                 dput(dir);
631                 dir = next;
632                 next = NULL;
633                 goto advance;
634         }
635 
636         /* we've found the object we were looking for */
637         object->dentry = next;
638 
639         /* if we've found that the terminal object exists, then we need to
640          * check its attributes and delete it if it's out of date */
641         if (!object->new) {
642                 _debug("validate '%pd'", next);
643 
644                 ret = cachefiles_check_object_xattr(object, auxdata);
645                 if (ret == -ESTALE) {
646                         /* delete the object (the deleter drops the directory
647                          * mutex) */
648                         object->dentry = NULL;
649 
650                         ret = cachefiles_bury_object(cache, object, dir, next,
651                                                      true,
652                                                      FSCACHE_OBJECT_IS_STALE);
653                         dput(next);
654                         next = NULL;
655 
656                         if (ret < 0)
657                                 goto delete_error;
658 
659                         _debug("redo lookup");
660                         fscache_object_retrying_stale(&object->fscache);
661                         goto lookup_again;
662                 }
663         }
664 
665         /* note that we're now using this object */
666         ret = cachefiles_mark_object_active(cache, object);
667 
668         inode_unlock(d_inode(dir));
669         dput(dir);
670         dir = NULL;
671 
672         if (ret == -ETIMEDOUT)
673                 goto mark_active_timed_out;
674 
675         _debug("=== OBTAINED_OBJECT ===");
676 
677         if (object->new) {
678                 /* attach data to a newly constructed terminal object */
679                 ret = cachefiles_set_object_xattr(object, auxdata);
680                 if (ret < 0)
681                         goto check_error;
682         } else {
683                 /* always update the atime on an object we've just looked up
684                  * (this is used to keep track of culling, and atimes are only
685                  * updated by read, write and readdir but not lookup or
686                  * open) */
687                 path.dentry = next;
688                 touch_atime(&path);
689         }
690 
691         /* open a file interface onto a data file */
692         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
693                 if (d_is_reg(object->dentry)) {
694                         const struct address_space_operations *aops;
695 
696                         ret = -EPERM;
697                         aops = d_backing_inode(object->dentry)->i_mapping->a_ops;
698                         if (!aops->bmap)
699                                 goto check_error;
700                         if (object->dentry->d_sb->s_blocksize > PAGE_SIZE)
701                                 goto check_error;
702 
703                         object->backer = object->dentry;
704                 } else {
705                         BUG(); // TODO: open file in data-class subdir
706                 }
707         }
708 
709         object->new = 0;
710         fscache_obtained_object(&object->fscache);
711 
712         _leave(" = 0 [%lu]", d_backing_inode(object->dentry)->i_ino);
713         return 0;
714 
715 no_space_error:
716         fscache_object_mark_killed(&object->fscache, FSCACHE_OBJECT_NO_SPACE);
717 create_error:
718         _debug("create error %d", ret);
719         if (ret == -EIO)
720                 cachefiles_io_error(cache, "Create/mkdir failed");
721         goto error;
722 
723 mark_active_timed_out:
724         _debug("mark active timed out");
725         goto release_dentry;
726 
727 check_error:
728         _debug("check error %d", ret);
729         cachefiles_mark_object_inactive(
730                 cache, object, d_backing_inode(object->dentry)->i_blocks);
731 release_dentry:
732         dput(object->dentry);
733         object->dentry = NULL;
734         goto error_out;
735 
736 delete_error:
737         _debug("delete error %d", ret);
738         goto error_out2;
739 
740 lookup_error:
741         _debug("lookup error %ld", PTR_ERR(next));
742         ret = PTR_ERR(next);
743         if (ret == -EIO)
744                 cachefiles_io_error(cache, "Lookup failed");
745         next = NULL;
746 error:
747         inode_unlock(d_inode(dir));
748         dput(next);
749 error_out2:
750         dput(dir);
751 error_out:
752         _leave(" = error %d", -ret);
753         return ret;
754 }
755 
756 /*
757  * get a subdirectory
758  */
759 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
760                                         struct dentry *dir,
761                                         const char *dirname)
762 {
763         struct dentry *subdir;
764         unsigned long start;
765         struct path path;
766         int ret;
767 
768         _enter(",,%s", dirname);
769 
770         /* search the current directory for the element name */
771         inode_lock(d_inode(dir));
772 
773 retry:
774         start = jiffies;
775         subdir = lookup_one_len(dirname, dir, strlen(dirname));
776         cachefiles_hist(cachefiles_lookup_histogram, start);
777         if (IS_ERR(subdir)) {
778                 if (PTR_ERR(subdir) == -ENOMEM)
779                         goto nomem_d_alloc;
780                 goto lookup_error;
781         }
782 
783         _debug("subdir -> %p %s",
784                subdir, d_backing_inode(subdir) ? "positive" : "negative");
785 
786         /* we need to create the subdir if it doesn't exist yet */
787         if (d_is_negative(subdir)) {
788                 ret = cachefiles_has_space(cache, 1, 0);
789                 if (ret < 0)
790                         goto mkdir_error;
791 
792                 _debug("attempt mkdir");
793 
794                 path.mnt = cache->mnt;
795                 path.dentry = dir;
796                 ret = security_path_mkdir(&path, subdir, 0700);
797                 if (ret < 0)
798                         goto mkdir_error;
799                 ret = vfs_mkdir(d_inode(dir), subdir, 0700);
800                 if (ret < 0)
801                         goto mkdir_error;
802 
803                 if (unlikely(d_unhashed(subdir))) {
804                         dput(subdir);
805                         goto retry;
806                 }
807                 ASSERT(d_backing_inode(subdir));
808 
809                 _debug("mkdir -> %p{%p{ino=%lu}}",
810                        subdir,
811                        d_backing_inode(subdir),
812                        d_backing_inode(subdir)->i_ino);
813         }
814 
815         inode_unlock(d_inode(dir));
816 
817         /* we need to make sure the subdir is a directory */
818         ASSERT(d_backing_inode(subdir));
819 
820         if (!d_can_lookup(subdir)) {
821                 pr_err("%s is not a directory\n", dirname);
822                 ret = -EIO;
823                 goto check_error;
824         }
825 
826         ret = -EPERM;
827         if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) ||
828             !d_backing_inode(subdir)->i_op->lookup ||
829             !d_backing_inode(subdir)->i_op->mkdir ||
830             !d_backing_inode(subdir)->i_op->create ||
831             !d_backing_inode(subdir)->i_op->rename ||
832             !d_backing_inode(subdir)->i_op->rmdir ||
833             !d_backing_inode(subdir)->i_op->unlink)
834                 goto check_error;
835 
836         _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
837         return subdir;
838 
839 check_error:
840         dput(subdir);
841         _leave(" = %d [check]", ret);
842         return ERR_PTR(ret);
843 
844 mkdir_error:
845         inode_unlock(d_inode(dir));
846         dput(subdir);
847         pr_err("mkdir %s failed with error %d\n", dirname, ret);
848         return ERR_PTR(ret);
849 
850 lookup_error:
851         inode_unlock(d_inode(dir));
852         ret = PTR_ERR(subdir);
853         pr_err("Lookup %s failed with error %d\n", dirname, ret);
854         return ERR_PTR(ret);
855 
856 nomem_d_alloc:
857         inode_unlock(d_inode(dir));
858         _leave(" = -ENOMEM");
859         return ERR_PTR(-ENOMEM);
860 }
861 
862 /*
863  * find out if an object is in use or not
864  * - if finds object and it's not in use:
865  *   - returns a pointer to the object and a reference on it
866  *   - returns with the directory locked
867  */
868 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
869                                               struct dentry *dir,
870                                               char *filename)
871 {
872         struct cachefiles_object *object;
873         struct rb_node *_n;
874         struct dentry *victim;
875         unsigned long start;
876         int ret;
877 
878         //_enter(",%pd/,%s",
879         //       dir, filename);
880 
881         /* look up the victim */
882         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
883 
884         start = jiffies;
885         victim = lookup_one_len(filename, dir, strlen(filename));
886         cachefiles_hist(cachefiles_lookup_histogram, start);
887         if (IS_ERR(victim))
888                 goto lookup_error;
889 
890         //_debug("victim -> %p %s",
891         //       victim, d_backing_inode(victim) ? "positive" : "negative");
892 
893         /* if the object is no longer there then we probably retired the object
894          * at the netfs's request whilst the cull was in progress
895          */
896         if (d_is_negative(victim)) {
897                 inode_unlock(d_inode(dir));
898                 dput(victim);
899                 _leave(" = -ENOENT [absent]");
900                 return ERR_PTR(-ENOENT);
901         }
902 
903         /* check to see if we're using this object */
904         read_lock(&cache->active_lock);
905 
906         _n = cache->active_nodes.rb_node;
907 
908         while (_n) {
909                 object = rb_entry(_n, struct cachefiles_object, active_node);
910 
911                 if (object->dentry > victim)
912                         _n = _n->rb_left;
913                 else if (object->dentry < victim)
914                         _n = _n->rb_right;
915                 else
916                         goto object_in_use;
917         }
918 
919         read_unlock(&cache->active_lock);
920 
921         //_leave(" = %p", victim);
922         return victim;
923 
924 object_in_use:
925         read_unlock(&cache->active_lock);
926         inode_unlock(d_inode(dir));
927         dput(victim);
928         //_leave(" = -EBUSY [in use]");
929         return ERR_PTR(-EBUSY);
930 
931 lookup_error:
932         inode_unlock(d_inode(dir));
933         ret = PTR_ERR(victim);
934         if (ret == -ENOENT) {
935                 /* file or dir now absent - probably retired by netfs */
936                 _leave(" = -ESTALE [absent]");
937                 return ERR_PTR(-ESTALE);
938         }
939 
940         if (ret == -EIO) {
941                 cachefiles_io_error(cache, "Lookup failed");
942         } else if (ret != -ENOMEM) {
943                 pr_err("Internal error: %d\n", ret);
944                 ret = -EIO;
945         }
946 
947         _leave(" = %d", ret);
948         return ERR_PTR(ret);
949 }
950 
951 /*
952  * cull an object if it's not in use
953  * - called only by cache manager daemon
954  */
955 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
956                     char *filename)
957 {
958         struct dentry *victim;
959         int ret;
960 
961         _enter(",%pd/,%s", dir, filename);
962 
963         victim = cachefiles_check_active(cache, dir, filename);
964         if (IS_ERR(victim))
965                 return PTR_ERR(victim);
966 
967         _debug("victim -> %p %s",
968                victim, d_backing_inode(victim) ? "positive" : "negative");
969 
970         /* okay... the victim is not being used so we can cull it
971          * - start by marking it as stale
972          */
973         _debug("victim is cullable");
974 
975         ret = cachefiles_remove_object_xattr(cache, victim);
976         if (ret < 0)
977                 goto error_unlock;
978 
979         /*  actually remove the victim (drops the dir mutex) */
980         _debug("bury");
981 
982         ret = cachefiles_bury_object(cache, NULL, dir, victim, false,
983                                      FSCACHE_OBJECT_WAS_CULLED);
984         if (ret < 0)
985                 goto error;
986 
987         dput(victim);
988         _leave(" = 0");
989         return 0;
990 
991 error_unlock:
992         inode_unlock(d_inode(dir));
993 error:
994         dput(victim);
995         if (ret == -ENOENT) {
996                 /* file or dir now absent - probably retired by netfs */
997                 _leave(" = -ESTALE [absent]");
998                 return -ESTALE;
999         }
1000 
1001         if (ret != -ENOMEM) {
1002                 pr_err("Internal error: %d\n", ret);
1003                 ret = -EIO;
1004         }
1005 
1006         _leave(" = %d", ret);
1007         return ret;
1008 }
1009 
1010 /*
1011  * find out if an object is in use or not
1012  * - called only by cache manager daemon
1013  * - returns -EBUSY or 0 to indicate whether an object is in use or not
1014  */
1015 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
1016                             char *filename)
1017 {
1018         struct dentry *victim;
1019 
1020         //_enter(",%pd/,%s",
1021         //       dir, filename);
1022 
1023         victim = cachefiles_check_active(cache, dir, filename);
1024         if (IS_ERR(victim))
1025                 return PTR_ERR(victim);
1026 
1027         inode_unlock(d_inode(dir));
1028         dput(victim);
1029         //_leave(" = 0");
1030         return 0;
1031 }
1032 

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