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

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