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

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