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

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /* CacheFiles path walking and related routines
  3  *
  4  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
  5  * Written by David Howells (dhowells@redhat.com)
  6  */
  7 
  8 #include <linux/module.h>
  9 #include <linux/sched.h>
 10 #include <linux/file.h>
 11 #include <linux/fs.h>
 12 #include <linux/fsnotify.h>
 13 #include <linux/quotaops.h>
 14 #include <linux/xattr.h>
 15 #include <linux/mount.h>
 16 #include <linux/namei.h>
 17 #include <linux/security.h>
 18 #include <linux/slab.h>
 19 #include "internal.h"
 20 
 21 #define CACHEFILES_KEYBUF_SIZE 512
 22 
 23 /*
 24  * dump debugging info about an object
 25  */
 26 static noinline
 27 void __cachefiles_printk_object(struct cachefiles_object *object,
 28                                 const char *prefix)
 29 {
 30         struct fscache_cookie *cookie;
 31         const u8 *k;
 32         unsigned loop;
 33 
 34         pr_err("%sobject: OBJ%x\n", prefix, object->fscache.debug_id);
 35         pr_err("%sobjstate=%s fl=%lx wbusy=%x ev=%lx[%lx]\n",
 36                prefix, object->fscache.state->name,
 37                object->fscache.flags, work_busy(&object->fscache.work),
 38                object->fscache.events, object->fscache.event_mask);
 39         pr_err("%sops=%u inp=%u exc=%u\n",
 40                prefix, object->fscache.n_ops, object->fscache.n_in_progress,
 41                object->fscache.n_exclusive);
 42         pr_err("%sparent=%p\n",
 43                prefix, object->fscache.parent);
 44 
 45         spin_lock(&object->fscache.lock);
 46         cookie = object->fscache.cookie;
 47         if (cookie) {
 48                 pr_err("%scookie=%p [pr=%p nd=%p fl=%lx]\n",
 49                        prefix,
 50                        object->fscache.cookie,
 51                        object->fscache.cookie->parent,
 52                        object->fscache.cookie->netfs_data,
 53                        object->fscache.cookie->flags);
 54                 pr_err("%skey=[%u] '", prefix, cookie->key_len);
 55                 k = (cookie->key_len <= sizeof(cookie->inline_key)) ?
 56                         cookie->inline_key : cookie->key;
 57                 for (loop = 0; loop < cookie->key_len; loop++)
 58                         pr_cont("%02x", k[loop]);
 59                 pr_cont("'\n");
 60         } else {
 61                 pr_err("%scookie=NULL\n", prefix);
 62         }
 63         spin_unlock(&object->fscache.lock);
 64 }
 65 
 66 /*
 67  * dump debugging info about a pair of objects
 68  */
 69 static noinline void cachefiles_printk_object(struct cachefiles_object *object,
 70                                               struct cachefiles_object *xobject)
 71 {
 72         if (object)
 73                 __cachefiles_printk_object(object, "");
 74         if (xobject)
 75                 __cachefiles_printk_object(xobject, "x");
 76 }
 77 
 78 /*
 79  * mark the owner of a dentry, if there is one, to indicate that that dentry
 80  * has been preemptively deleted
 81  * - the caller must hold the i_mutex on the dentry's parent as required to
 82  *   call vfs_unlink(), vfs_rmdir() or vfs_rename()
 83  */
 84 static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
 85                                           struct dentry *dentry,
 86                                           enum fscache_why_object_killed why)
 87 {
 88         struct cachefiles_object *object;
 89         struct rb_node *p;
 90 
 91         _enter(",'%pd'", dentry);
 92 
 93         write_lock(&cache->active_lock);
 94 
 95         p = cache->active_nodes.rb_node;
 96         while (p) {
 97                 object = rb_entry(p, struct cachefiles_object, active_node);
 98                 if (object->dentry > dentry)
 99                         p = p->rb_left;
100                 else if (object->dentry < dentry)
101                         p = p->rb_right;
102                 else
103                         goto found_dentry;
104         }
105 
106         write_unlock(&cache->active_lock);
107         trace_cachefiles_mark_buried(NULL, dentry, why);
108         _leave(" [no owner]");
109         return;
110 
111         /* found the dentry for  */
112 found_dentry:
113         kdebug("preemptive burial: OBJ%x [%s] %p",
114                object->fscache.debug_id,
115                object->fscache.state->name,
116                dentry);
117 
118         trace_cachefiles_mark_buried(object, dentry, why);
119 
120         if (fscache_object_is_live(&object->fscache)) {
121                 pr_err("\n");
122                 pr_err("Error: Can't preemptively bury live object\n");
123                 cachefiles_printk_object(object, NULL);
124         } else {
125                 if (why != FSCACHE_OBJECT_IS_STALE)
126                         fscache_object_mark_killed(&object->fscache, why);
127         }
128 
129         write_unlock(&cache->active_lock);
130         _leave(" [owner marked]");
131 }
132 
133 /*
134  * record the fact that an object is now active
135  */
136 static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
137                                          struct cachefiles_object *object)
138 {
139         struct cachefiles_object *xobject;
140         struct rb_node **_p, *_parent = NULL;
141         struct dentry *dentry;
142 
143         _enter(",%p", object);
144 
145 try_again:
146         write_lock(&cache->active_lock);
147 
148         dentry = object->dentry;
149         trace_cachefiles_mark_active(object, dentry);
150 
151         if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
152                 pr_err("Error: Object already active\n");
153                 cachefiles_printk_object(object, NULL);
154                 BUG();
155         }
156 
157         _p = &cache->active_nodes.rb_node;
158         while (*_p) {
159                 _parent = *_p;
160                 xobject = rb_entry(_parent,
161                                    struct cachefiles_object, active_node);
162 
163                 ASSERT(xobject != object);
164 
165                 if (xobject->dentry > dentry)
166                         _p = &(*_p)->rb_left;
167                 else if (xobject->dentry < dentry)
168                         _p = &(*_p)->rb_right;
169                 else
170                         goto wait_for_old_object;
171         }
172 
173         rb_link_node(&object->active_node, _parent, _p);
174         rb_insert_color(&object->active_node, &cache->active_nodes);
175 
176         write_unlock(&cache->active_lock);
177         _leave(" = 0");
178         return 0;
179 
180         /* an old object from a previous incarnation is hogging the slot - we
181          * need to wait for it to be destroyed */
182 wait_for_old_object:
183         trace_cachefiles_wait_active(object, dentry, xobject);
184         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
185 
186         if (fscache_object_is_live(&xobject->fscache)) {
187                 pr_err("\n");
188                 pr_err("Error: Unexpected object collision\n");
189                 cachefiles_printk_object(object, xobject);
190         }
191         atomic_inc(&xobject->usage);
192         write_unlock(&cache->active_lock);
193 
194         if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
195                 wait_queue_head_t *wq;
196 
197                 signed long timeout = 60 * HZ;
198                 wait_queue_entry_t wait;
199                 bool requeue;
200 
201                 /* if the object we're waiting for is queued for processing,
202                  * then just put ourselves on the queue behind it */
203                 if (work_pending(&xobject->fscache.work)) {
204                         _debug("queue OBJ%x behind OBJ%x immediately",
205                                object->fscache.debug_id,
206                                xobject->fscache.debug_id);
207                         goto requeue;
208                 }
209 
210                 /* otherwise we sleep until either the object we're waiting for
211                  * is done, or the fscache_object is congested */
212                 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
213                 init_wait(&wait);
214                 requeue = false;
215                 do {
216                         prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
217                         if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
218                                 break;
219 
220                         requeue = fscache_object_sleep_till_congested(&timeout);
221                 } while (timeout > 0 && !requeue);
222                 finish_wait(wq, &wait);
223 
224                 if (requeue &&
225                     test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
226                         _debug("queue OBJ%x behind OBJ%x after wait",
227                                object->fscache.debug_id,
228                                xobject->fscache.debug_id);
229                         goto requeue;
230                 }
231 
232                 if (timeout <= 0) {
233                         pr_err("\n");
234                         pr_err("Error: Overlong wait for old active object to go away\n");
235                         cachefiles_printk_object(object, xobject);
236                         goto requeue;
237                 }
238         }
239 
240         ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
241 
242         cache->cache.ops->put_object(&xobject->fscache,
243                 (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_retry);
244         goto try_again;
245 
246 requeue:
247         cache->cache.ops->put_object(&xobject->fscache,
248                 (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_timeo);
249         _leave(" = -ETIMEDOUT");
250         return -ETIMEDOUT;
251 }
252 
253 /*
254  * Mark an object as being inactive.
255  */
256 void cachefiles_mark_object_inactive(struct cachefiles_cache *cache,
257                                      struct cachefiles_object *object,
258                                      blkcnt_t i_blocks)
259 {
260         struct dentry *dentry = object->dentry;
261         struct inode *inode = d_backing_inode(dentry);
262 
263         trace_cachefiles_mark_inactive(object, dentry, inode);
264 
265         write_lock(&cache->active_lock);
266         rb_erase(&object->active_node, &cache->active_nodes);
267         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
268         write_unlock(&cache->active_lock);
269 
270         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
271 
272         /* This object can now be culled, so we need to let the daemon know
273          * that there is something it can remove if it needs to.
274          */
275         atomic_long_add(i_blocks, &cache->b_released);
276         if (atomic_inc_return(&cache->f_released))
277                 cachefiles_state_changed(cache);
278 }
279 
280 /*
281  * delete an object representation from the cache
282  * - file backed objects are unlinked
283  * - directory backed objects are stuffed into the graveyard for userspace to
284  *   delete
285  * - unlocks the directory mutex
286  */
287 static int cachefiles_bury_object(struct cachefiles_cache *cache,
288                                   struct cachefiles_object *object,
289                                   struct dentry *dir,
290                                   struct dentry *rep,
291                                   bool preemptive,
292                                   enum fscache_why_object_killed why)
293 {
294         struct dentry *grave, *trap;
295         struct path path, path_to_graveyard;
296         char nbuffer[8 + 8 + 1];
297         int ret;
298 
299         _enter(",'%pd','%pd'", dir, rep);
300 
301         _debug("remove %p from %p", rep, dir);
302 
303         /* non-directories can just be unlinked */
304         if (!d_is_dir(rep)) {
305                 _debug("unlink stale object");
306 
307                 path.mnt = cache->mnt;
308                 path.dentry = dir;
309                 ret = security_path_unlink(&path, rep);
310                 if (ret < 0) {
311                         cachefiles_io_error(cache, "Unlink security error");
312                 } else {
313                         trace_cachefiles_unlink(object, rep, why);
314                         ret = vfs_unlink(d_inode(dir), rep, NULL);
315 
316                         if (preemptive)
317                                 cachefiles_mark_object_buried(cache, rep, why);
318                 }
319 
320                 inode_unlock(d_inode(dir));
321 
322                 if (ret == -EIO)
323                         cachefiles_io_error(cache, "Unlink failed");
324 
325                 _leave(" = %d", ret);
326                 return ret;
327         }
328 
329         /* directories have to be moved to the graveyard */
330         _debug("move stale object to graveyard");
331         inode_unlock(d_inode(dir));
332 
333 try_again:
334         /* first step is to make up a grave dentry in the graveyard */
335         sprintf(nbuffer, "%08x%08x",
336                 (uint32_t) ktime_get_real_seconds(),
337                 (uint32_t) atomic_inc_return(&cache->gravecounter));
338 
339         /* do the multiway lock magic */
340         trap = lock_rename(cache->graveyard, dir);
341 
342         /* do some checks before getting the grave dentry */
343         if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) {
344                 /* the entry was probably culled when we dropped the parent dir
345                  * lock */
346                 unlock_rename(cache->graveyard, dir);
347                 _leave(" = 0 [culled?]");
348                 return 0;
349         }
350 
351         if (!d_can_lookup(cache->graveyard)) {
352                 unlock_rename(cache->graveyard, dir);
353                 cachefiles_io_error(cache, "Graveyard no longer a directory");
354                 return -EIO;
355         }
356 
357         if (trap == rep) {
358                 unlock_rename(cache->graveyard, dir);
359                 cachefiles_io_error(cache, "May not make directory loop");
360                 return -EIO;
361         }
362 
363         if (d_mountpoint(rep)) {
364                 unlock_rename(cache->graveyard, dir);
365                 cachefiles_io_error(cache, "Mountpoint in cache");
366                 return -EIO;
367         }
368 
369         grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
370         if (IS_ERR(grave)) {
371                 unlock_rename(cache->graveyard, dir);
372 
373                 if (PTR_ERR(grave) == -ENOMEM) {
374                         _leave(" = -ENOMEM");
375                         return -ENOMEM;
376                 }
377 
378                 cachefiles_io_error(cache, "Lookup error %ld",
379                                     PTR_ERR(grave));
380                 return -EIO;
381         }
382 
383         if (d_is_positive(grave)) {
384                 unlock_rename(cache->graveyard, dir);
385                 dput(grave);
386                 grave = NULL;
387                 cond_resched();
388                 goto try_again;
389         }
390 
391         if (d_mountpoint(grave)) {
392                 unlock_rename(cache->graveyard, dir);
393                 dput(grave);
394                 cachefiles_io_error(cache, "Mountpoint in graveyard");
395                 return -EIO;
396         }
397 
398         /* target should not be an ancestor of source */
399         if (trap == grave) {
400                 unlock_rename(cache->graveyard, dir);
401                 dput(grave);
402                 cachefiles_io_error(cache, "May not make directory loop");
403                 return -EIO;
404         }
405 
406         /* attempt the rename */
407         path.mnt = cache->mnt;
408         path.dentry = dir;
409         path_to_graveyard.mnt = cache->mnt;
410         path_to_graveyard.dentry = cache->graveyard;
411         ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0);
412         if (ret < 0) {
413                 cachefiles_io_error(cache, "Rename security error %d", ret);
414         } else {
415                 trace_cachefiles_rename(object, rep, grave, why);
416                 ret = vfs_rename(d_inode(dir), rep,
417                                  d_inode(cache->graveyard), grave, NULL, 0);
418                 if (ret != 0 && ret != -ENOMEM)
419                         cachefiles_io_error(cache,
420                                             "Rename failed with error %d", ret);
421 
422                 if (preemptive)
423                         cachefiles_mark_object_buried(cache, rep, why);
424         }
425 
426         unlock_rename(cache->graveyard, dir);
427         dput(grave);
428         _leave(" = 0");
429         return 0;
430 }
431 
432 /*
433  * delete an object representation from the cache
434  */
435 int cachefiles_delete_object(struct cachefiles_cache *cache,
436                              struct cachefiles_object *object)
437 {
438         struct dentry *dir;
439         int ret;
440 
441         _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
442 
443         ASSERT(object->dentry);
444         ASSERT(d_backing_inode(object->dentry));
445         ASSERT(object->dentry->d_parent);
446 
447         dir = dget_parent(object->dentry);
448 
449         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
450 
451         if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
452                 /* object allocation for the same key preemptively deleted this
453                  * object's file so that it could create its own file */
454                 _debug("object preemptively buried");
455                 inode_unlock(d_inode(dir));
456                 ret = 0;
457         } else {
458                 /* we need to check that our parent is _still_ our parent - it
459                  * may have been renamed */
460                 if (dir == object->dentry->d_parent) {
461                         ret = cachefiles_bury_object(cache, object, dir,
462                                                      object->dentry, false,
463                                                      FSCACHE_OBJECT_WAS_RETIRED);
464                 } else {
465                         /* it got moved, presumably by cachefilesd culling it,
466                          * so it's no longer in the key path and we can ignore
467                          * it */
468                         inode_unlock(d_inode(dir));
469                         ret = 0;
470                 }
471         }
472 
473         dput(dir);
474         _leave(" = %d", ret);
475         return ret;
476 }
477 
478 /*
479  * walk from the parent object to the child object through the backing
480  * filesystem, creating directories as we go
481  */
482 int cachefiles_walk_to_object(struct cachefiles_object *parent,
483                               struct cachefiles_object *object,
484                               const char *key,
485                               struct cachefiles_xattr *auxdata)
486 {
487         struct cachefiles_cache *cache;
488         struct dentry *dir, *next = NULL;
489         struct inode *inode;
490         struct path path;
491         unsigned long start;
492         const char *name;
493         int ret, nlen;
494 
495         _enter("OBJ%x{%p},OBJ%x,%s,",
496                parent->fscache.debug_id, parent->dentry,
497                object->fscache.debug_id, key);
498 
499         cache = container_of(parent->fscache.cache,
500                              struct cachefiles_cache, cache);
501         path.mnt = cache->mnt;
502 
503         ASSERT(parent->dentry);
504         ASSERT(d_backing_inode(parent->dentry));
505 
506         if (!(d_is_dir(parent->dentry))) {
507                 // TODO: convert file to dir
508                 _leave("looking up in none directory");
509                 return -ENOBUFS;
510         }
511 
512         dir = dget(parent->dentry);
513 
514 advance:
515         /* attempt to transit the first directory component */
516         name = key;
517         nlen = strlen(key);
518 
519         /* key ends in a double NUL */
520         key = key + nlen + 1;
521         if (!*key)
522                 key = NULL;
523 
524 lookup_again:
525         /* search the current directory for the element name */
526         _debug("lookup '%s'", name);
527 
528         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
529 
530         start = jiffies;
531         next = lookup_one_len(name, dir, nlen);
532         cachefiles_hist(cachefiles_lookup_histogram, start);
533         if (IS_ERR(next)) {
534                 trace_cachefiles_lookup(object, next, NULL);
535                 goto lookup_error;
536         }
537 
538         inode = d_backing_inode(next);
539         trace_cachefiles_lookup(object, next, inode);
540         _debug("next -> %p %s", next, inode ? "positive" : "negative");
541 
542         if (!key)
543                 object->new = !inode;
544 
545         /* if this element of the path doesn't exist, then the lookup phase
546          * failed, and we can release any readers in the certain knowledge that
547          * there's nothing for them to actually read */
548         if (d_is_negative(next))
549                 fscache_object_lookup_negative(&object->fscache);
550 
551         /* we need to create the object if it's negative */
552         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
553                 /* index objects and intervening tree levels must be subdirs */
554                 if (d_is_negative(next)) {
555                         ret = cachefiles_has_space(cache, 1, 0);
556                         if (ret < 0)
557                                 goto no_space_error;
558 
559                         path.dentry = dir;
560                         ret = security_path_mkdir(&path, next, 0);
561                         if (ret < 0)
562                                 goto create_error;
563                         start = jiffies;
564                         ret = vfs_mkdir(d_inode(dir), next, 0);
565                         cachefiles_hist(cachefiles_mkdir_histogram, start);
566                         if (!key)
567                                 trace_cachefiles_mkdir(object, next, ret);
568                         if (ret < 0)
569                                 goto create_error;
570 
571                         if (unlikely(d_unhashed(next))) {
572                                 dput(next);
573                                 inode_unlock(d_inode(dir));
574                                 goto lookup_again;
575                         }
576                         ASSERT(d_backing_inode(next));
577 
578                         _debug("mkdir -> %p{%p{ino=%lu}}",
579                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
580 
581                 } else if (!d_can_lookup(next)) {
582                         pr_err("inode %lu is not a directory\n",
583                                d_backing_inode(next)->i_ino);
584                         ret = -ENOBUFS;
585                         goto error;
586                 }
587 
588         } else {
589                 /* non-index objects start out life as files */
590                 if (d_is_negative(next)) {
591                         ret = cachefiles_has_space(cache, 1, 0);
592                         if (ret < 0)
593                                 goto no_space_error;
594 
595                         path.dentry = dir;
596                         ret = security_path_mknod(&path, next, S_IFREG, 0);
597                         if (ret < 0)
598                                 goto create_error;
599                         start = jiffies;
600                         ret = vfs_create(d_inode(dir), next, S_IFREG, true);
601                         cachefiles_hist(cachefiles_create_histogram, start);
602                         trace_cachefiles_create(object, next, ret);
603                         if (ret < 0)
604                                 goto create_error;
605 
606                         ASSERT(d_backing_inode(next));
607 
608                         _debug("create -> %p{%p{ino=%lu}}",
609                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
610 
611                 } else if (!d_can_lookup(next) &&
612                            !d_is_reg(next)
613                            ) {
614                         pr_err("inode %lu is not a file or directory\n",
615                                d_backing_inode(next)->i_ino);
616                         ret = -ENOBUFS;
617                         goto error;
618                 }
619         }
620 
621         /* process the next component */
622         if (key) {
623                 _debug("advance");
624                 inode_unlock(d_inode(dir));
625                 dput(dir);
626                 dir = next;
627                 next = NULL;
628                 goto advance;
629         }
630 
631         /* we've found the object we were looking for */
632         object->dentry = next;
633 
634         /* if we've found that the terminal object exists, then we need to
635          * check its attributes and delete it if it's out of date */
636         if (!object->new) {
637                 _debug("validate '%pd'", next);
638 
639                 ret = cachefiles_check_object_xattr(object, auxdata);
640                 if (ret == -ESTALE) {
641                         /* delete the object (the deleter drops the directory
642                          * mutex) */
643                         object->dentry = NULL;
644 
645                         ret = cachefiles_bury_object(cache, object, dir, next,
646                                                      true,
647                                                      FSCACHE_OBJECT_IS_STALE);
648                         dput(next);
649                         next = NULL;
650 
651                         if (ret < 0)
652                                 goto delete_error;
653 
654                         _debug("redo lookup");
655                         fscache_object_retrying_stale(&object->fscache);
656                         goto lookup_again;
657                 }
658         }
659 
660         /* note that we're now using this object */
661         ret = cachefiles_mark_object_active(cache, object);
662 
663         inode_unlock(d_inode(dir));
664         dput(dir);
665         dir = NULL;
666 
667         if (ret == -ETIMEDOUT)
668                 goto mark_active_timed_out;
669 
670         _debug("=== OBTAINED_OBJECT ===");
671 
672         if (object->new) {
673                 /* attach data to a newly constructed terminal object */
674                 ret = cachefiles_set_object_xattr(object, auxdata);
675                 if (ret < 0)
676                         goto check_error;
677         } else {
678                 /* always update the atime on an object we've just looked up
679                  * (this is used to keep track of culling, and atimes are only
680                  * updated by read, write and readdir but not lookup or
681                  * open) */
682                 path.dentry = next;
683                 touch_atime(&path);
684         }
685 
686         /* open a file interface onto a data file */
687         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
688                 if (d_is_reg(object->dentry)) {
689                         const struct address_space_operations *aops;
690 
691                         ret = -EPERM;
692                         aops = d_backing_inode(object->dentry)->i_mapping->a_ops;
693                         if (!aops->bmap)
694                                 goto check_error;
695                         if (object->dentry->d_sb->s_blocksize > PAGE_SIZE)
696                                 goto check_error;
697 
698                         object->backer = object->dentry;
699                 } else {
700                         BUG(); // TODO: open file in data-class subdir
701                 }
702         }
703 
704         object->new = 0;
705         fscache_obtained_object(&object->fscache);
706 
707         _leave(" = 0 [%lu]", d_backing_inode(object->dentry)->i_ino);
708         return 0;
709 
710 no_space_error:
711         fscache_object_mark_killed(&object->fscache, FSCACHE_OBJECT_NO_SPACE);
712 create_error:
713         _debug("create error %d", ret);
714         if (ret == -EIO)
715                 cachefiles_io_error(cache, "Create/mkdir failed");
716         goto error;
717 
718 mark_active_timed_out:
719         _debug("mark active timed out");
720         goto release_dentry;
721 
722 check_error:
723         _debug("check error %d", ret);
724         cachefiles_mark_object_inactive(
725                 cache, object, d_backing_inode(object->dentry)->i_blocks);
726 release_dentry:
727         dput(object->dentry);
728         object->dentry = NULL;
729         goto error_out;
730 
731 delete_error:
732         _debug("delete error %d", ret);
733         goto error_out2;
734 
735 lookup_error:
736         _debug("lookup error %ld", PTR_ERR(next));
737         ret = PTR_ERR(next);
738         if (ret == -EIO)
739                 cachefiles_io_error(cache, "Lookup failed");
740         next = NULL;
741 error:
742         inode_unlock(d_inode(dir));
743         dput(next);
744 error_out2:
745         dput(dir);
746 error_out:
747         _leave(" = error %d", -ret);
748         return ret;
749 }
750 
751 /*
752  * get a subdirectory
753  */
754 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
755                                         struct dentry *dir,
756                                         const char *dirname)
757 {
758         struct dentry *subdir;
759         unsigned long start;
760         struct path path;
761         int ret;
762 
763         _enter(",,%s", dirname);
764 
765         /* search the current directory for the element name */
766         inode_lock(d_inode(dir));
767 
768 retry:
769         start = jiffies;
770         subdir = lookup_one_len(dirname, dir, strlen(dirname));
771         cachefiles_hist(cachefiles_lookup_histogram, start);
772         if (IS_ERR(subdir)) {
773                 if (PTR_ERR(subdir) == -ENOMEM)
774                         goto nomem_d_alloc;
775                 goto lookup_error;
776         }
777 
778         _debug("subdir -> %p %s",
779                subdir, d_backing_inode(subdir) ? "positive" : "negative");
780 
781         /* we need to create the subdir if it doesn't exist yet */
782         if (d_is_negative(subdir)) {
783                 ret = cachefiles_has_space(cache, 1, 0);
784                 if (ret < 0)
785                         goto mkdir_error;
786 
787                 _debug("attempt mkdir");
788 
789                 path.mnt = cache->mnt;
790                 path.dentry = dir;
791                 ret = security_path_mkdir(&path, subdir, 0700);
792                 if (ret < 0)
793                         goto mkdir_error;
794                 ret = vfs_mkdir(d_inode(dir), subdir, 0700);
795                 if (ret < 0)
796                         goto mkdir_error;
797 
798                 if (unlikely(d_unhashed(subdir))) {
799                         dput(subdir);
800                         goto retry;
801                 }
802                 ASSERT(d_backing_inode(subdir));
803 
804                 _debug("mkdir -> %p{%p{ino=%lu}}",
805                        subdir,
806                        d_backing_inode(subdir),
807                        d_backing_inode(subdir)->i_ino);
808         }
809 
810         inode_unlock(d_inode(dir));
811 
812         /* we need to make sure the subdir is a directory */
813         ASSERT(d_backing_inode(subdir));
814 
815         if (!d_can_lookup(subdir)) {
816                 pr_err("%s is not a directory\n", dirname);
817                 ret = -EIO;
818                 goto check_error;
819         }
820 
821         ret = -EPERM;
822         if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) ||
823             !d_backing_inode(subdir)->i_op->lookup ||
824             !d_backing_inode(subdir)->i_op->mkdir ||
825             !d_backing_inode(subdir)->i_op->create ||
826             !d_backing_inode(subdir)->i_op->rename ||
827             !d_backing_inode(subdir)->i_op->rmdir ||
828             !d_backing_inode(subdir)->i_op->unlink)
829                 goto check_error;
830 
831         _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
832         return subdir;
833 
834 check_error:
835         dput(subdir);
836         _leave(" = %d [check]", ret);
837         return ERR_PTR(ret);
838 
839 mkdir_error:
840         inode_unlock(d_inode(dir));
841         dput(subdir);
842         pr_err("mkdir %s failed with error %d\n", dirname, ret);
843         return ERR_PTR(ret);
844 
845 lookup_error:
846         inode_unlock(d_inode(dir));
847         ret = PTR_ERR(subdir);
848         pr_err("Lookup %s failed with error %d\n", dirname, ret);
849         return ERR_PTR(ret);
850 
851 nomem_d_alloc:
852         inode_unlock(d_inode(dir));
853         _leave(" = -ENOMEM");
854         return ERR_PTR(-ENOMEM);
855 }
856 
857 /*
858  * find out if an object is in use or not
859  * - if finds object and it's not in use:
860  *   - returns a pointer to the object and a reference on it
861  *   - returns with the directory locked
862  */
863 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
864                                               struct dentry *dir,
865                                               char *filename)
866 {
867         struct cachefiles_object *object;
868         struct rb_node *_n;
869         struct dentry *victim;
870         unsigned long start;
871         int ret;
872 
873         //_enter(",%pd/,%s",
874         //       dir, filename);
875 
876         /* look up the victim */
877         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
878 
879         start = jiffies;
880         victim = lookup_one_len(filename, dir, strlen(filename));
881         cachefiles_hist(cachefiles_lookup_histogram, start);
882         if (IS_ERR(victim))
883                 goto lookup_error;
884 
885         //_debug("victim -> %p %s",
886         //       victim, d_backing_inode(victim) ? "positive" : "negative");
887 
888         /* if the object is no longer there then we probably retired the object
889          * at the netfs's request whilst the cull was in progress
890          */
891         if (d_is_negative(victim)) {
892                 inode_unlock(d_inode(dir));
893                 dput(victim);
894                 _leave(" = -ENOENT [absent]");
895                 return ERR_PTR(-ENOENT);
896         }
897 
898         /* check to see if we're using this object */
899         read_lock(&cache->active_lock);
900 
901         _n = cache->active_nodes.rb_node;
902 
903         while (_n) {
904                 object = rb_entry(_n, struct cachefiles_object, active_node);
905 
906                 if (object->dentry > victim)
907                         _n = _n->rb_left;
908                 else if (object->dentry < victim)
909                         _n = _n->rb_right;
910                 else
911                         goto object_in_use;
912         }
913 
914         read_unlock(&cache->active_lock);
915 
916         //_leave(" = %p", victim);
917         return victim;
918 
919 object_in_use:
920         read_unlock(&cache->active_lock);
921         inode_unlock(d_inode(dir));
922         dput(victim);
923         //_leave(" = -EBUSY [in use]");
924         return ERR_PTR(-EBUSY);
925 
926 lookup_error:
927         inode_unlock(d_inode(dir));
928         ret = PTR_ERR(victim);
929         if (ret == -ENOENT) {
930                 /* file or dir now absent - probably retired by netfs */
931                 _leave(" = -ESTALE [absent]");
932                 return ERR_PTR(-ESTALE);
933         }
934 
935         if (ret == -EIO) {
936                 cachefiles_io_error(cache, "Lookup failed");
937         } else if (ret != -ENOMEM) {
938                 pr_err("Internal error: %d\n", ret);
939                 ret = -EIO;
940         }
941 
942         _leave(" = %d", ret);
943         return ERR_PTR(ret);
944 }
945 
946 /*
947  * cull an object if it's not in use
948  * - called only by cache manager daemon
949  */
950 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
951                     char *filename)
952 {
953         struct dentry *victim;
954         int ret;
955 
956         _enter(",%pd/,%s", dir, filename);
957 
958         victim = cachefiles_check_active(cache, dir, filename);
959         if (IS_ERR(victim))
960                 return PTR_ERR(victim);
961 
962         _debug("victim -> %p %s",
963                victim, d_backing_inode(victim) ? "positive" : "negative");
964 
965         /* okay... the victim is not being used so we can cull it
966          * - start by marking it as stale
967          */
968         _debug("victim is cullable");
969 
970         ret = cachefiles_remove_object_xattr(cache, victim);
971         if (ret < 0)
972                 goto error_unlock;
973 
974         /*  actually remove the victim (drops the dir mutex) */
975         _debug("bury");
976 
977         ret = cachefiles_bury_object(cache, NULL, dir, victim, false,
978                                      FSCACHE_OBJECT_WAS_CULLED);
979         if (ret < 0)
980                 goto error;
981 
982         dput(victim);
983         _leave(" = 0");
984         return 0;
985 
986 error_unlock:
987         inode_unlock(d_inode(dir));
988 error:
989         dput(victim);
990         if (ret == -ENOENT) {
991                 /* file or dir now absent - probably retired by netfs */
992                 _leave(" = -ESTALE [absent]");
993                 return -ESTALE;
994         }
995 
996         if (ret != -ENOMEM) {
997                 pr_err("Internal error: %d\n", ret);
998                 ret = -EIO;
999         }
1000 
1001         _leave(" = %d", ret);
1002         return ret;
1003 }
1004 
1005 /*
1006  * find out if an object is in use or not
1007  * - called only by cache manager daemon
1008  * - returns -EBUSY or 0 to indicate whether an object is in use or not
1009  */
1010 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
1011                             char *filename)
1012 {
1013         struct dentry *victim;
1014 
1015         //_enter(",%pd/,%s",
1016         //       dir, filename);
1017 
1018         victim = cachefiles_check_active(cache, dir, filename);
1019         if (IS_ERR(victim))
1020                 return PTR_ERR(victim);
1021 
1022         inode_unlock(d_inode(dir));
1023         dput(victim);
1024         //_leave(" = 0");
1025         return 0;
1026 }
1027 

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