~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

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

Version: ~ [ linux-5.4-rc7 ] ~ [ linux-5.3.10 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.83 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.153 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.200 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.200 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.76 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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         pr_err("%sobject: OBJ%x\n", prefix, object->fscache.debug_id);
 39         pr_err("%sobjstate=%s fl=%lx wbusy=%x ev=%lx[%lx]\n",
 40                prefix, object->fscache.state->name,
 41                object->fscache.flags, work_busy(&object->fscache.work),
 42                object->fscache.events, object->fscache.event_mask);
 43         pr_err("%sops=%u inp=%u exc=%u\n",
 44                prefix, object->fscache.n_ops, object->fscache.n_in_progress,
 45                object->fscache.n_exclusive);
 46         pr_err("%sparent=%p\n",
 47                prefix, object->fscache.parent);
 48 
 49         spin_lock(&object->fscache.lock);
 50         cookie = object->fscache.cookie;
 51         if (cookie) {
 52                 pr_err("%scookie=%p [pr=%p nd=%p fl=%lx]\n",
 53                        prefix,
 54                        object->fscache.cookie,
 55                        object->fscache.cookie->parent,
 56                        object->fscache.cookie->netfs_data,
 57                        object->fscache.cookie->flags);
 58                 if (keybuf && cookie->def)
 59                         keylen = cookie->def->get_key(cookie->netfs_data, keybuf,
 60                                                       CACHEFILES_KEYBUF_SIZE);
 61                 else
 62                         keylen = 0;
 63         } else {
 64                 pr_err("%scookie=NULL\n", prefix);
 65                 keylen = 0;
 66         }
 67         spin_unlock(&object->fscache.lock);
 68 
 69         if (keylen) {
 70                 pr_err("%skey=[%u] '", prefix, keylen);
 71                 for (loop = 0; loop < keylen; loop++)
 72                         pr_cont("%02x", keybuf[loop]);
 73                 pr_cont("'\n");
 74         }
 75 }
 76 
 77 /*
 78  * dump debugging info about a pair of objects
 79  */
 80 static noinline void cachefiles_printk_object(struct cachefiles_object *object,
 81                                               struct cachefiles_object *xobject)
 82 {
 83         u8 *keybuf;
 84 
 85         keybuf = kmalloc(CACHEFILES_KEYBUF_SIZE, GFP_NOIO);
 86         if (object)
 87                 __cachefiles_printk_object(object, "", keybuf);
 88         if (xobject)
 89                 __cachefiles_printk_object(xobject, "x", keybuf);
 90         kfree(keybuf);
 91 }
 92 
 93 /*
 94  * mark the owner of a dentry, if there is one, to indicate that that dentry
 95  * has been preemptively deleted
 96  * - the caller must hold the i_mutex on the dentry's parent as required to
 97  *   call vfs_unlink(), vfs_rmdir() or vfs_rename()
 98  */
 99 static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
100                                           struct dentry *dentry,
101                                           enum fscache_why_object_killed why)
102 {
103         struct cachefiles_object *object;
104         struct rb_node *p;
105 
106         _enter(",'%pd'", dentry);
107 
108         write_lock(&cache->active_lock);
109 
110         p = cache->active_nodes.rb_node;
111         while (p) {
112                 object = rb_entry(p, struct cachefiles_object, active_node);
113                 if (object->dentry > dentry)
114                         p = p->rb_left;
115                 else if (object->dentry < dentry)
116                         p = p->rb_right;
117                 else
118                         goto found_dentry;
119         }
120 
121         write_unlock(&cache->active_lock);
122         _leave(" [no owner]");
123         return;
124 
125         /* found the dentry for  */
126 found_dentry:
127         kdebug("preemptive burial: OBJ%x [%s] %p",
128                object->fscache.debug_id,
129                object->fscache.state->name,
130                dentry);
131 
132         if (fscache_object_is_live(&object->fscache)) {
133                 pr_err("\n");
134                 pr_err("Error: Can't preemptively bury live object\n");
135                 cachefiles_printk_object(object, NULL);
136         } else {
137                 if (why != FSCACHE_OBJECT_IS_STALE)
138                         fscache_object_mark_killed(&object->fscache, why);
139         }
140 
141         write_unlock(&cache->active_lock);
142         _leave(" [owner marked]");
143 }
144 
145 /*
146  * record the fact that an object is now active
147  */
148 static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
149                                          struct cachefiles_object *object)
150 {
151         struct cachefiles_object *xobject;
152         struct rb_node **_p, *_parent = NULL;
153         struct dentry *dentry;
154 
155         _enter(",%p", object);
156 
157 try_again:
158         write_lock(&cache->active_lock);
159 
160         if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
161                 pr_err("Error: Object already active\n");
162                 cachefiles_printk_object(object, NULL);
163                 BUG();
164         }
165 
166         dentry = object->dentry;
167         _p = &cache->active_nodes.rb_node;
168         while (*_p) {
169                 _parent = *_p;
170                 xobject = rb_entry(_parent,
171                                    struct cachefiles_object, active_node);
172 
173                 ASSERT(xobject != object);
174 
175                 if (xobject->dentry > dentry)
176                         _p = &(*_p)->rb_left;
177                 else if (xobject->dentry < dentry)
178                         _p = &(*_p)->rb_right;
179                 else
180                         goto wait_for_old_object;
181         }
182 
183         rb_link_node(&object->active_node, _parent, _p);
184         rb_insert_color(&object->active_node, &cache->active_nodes);
185 
186         write_unlock(&cache->active_lock);
187         _leave(" = 0");
188         return 0;
189 
190         /* an old object from a previous incarnation is hogging the slot - we
191          * need to wait for it to be destroyed */
192 wait_for_old_object:
193         if (fscache_object_is_live(&xobject->fscache)) {
194                 pr_err("\n");
195                 pr_err("Error: Unexpected object collision\n");
196                 cachefiles_printk_object(object, xobject);
197                 BUG();
198         }
199         atomic_inc(&xobject->usage);
200         write_unlock(&cache->active_lock);
201 
202         if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
203                 wait_queue_head_t *wq;
204 
205                 signed long timeout = 60 * HZ;
206                 wait_queue_t wait;
207                 bool requeue;
208 
209                 /* if the object we're waiting for is queued for processing,
210                  * then just put ourselves on the queue behind it */
211                 if (work_pending(&xobject->fscache.work)) {
212                         _debug("queue OBJ%x behind OBJ%x immediately",
213                                object->fscache.debug_id,
214                                xobject->fscache.debug_id);
215                         goto requeue;
216                 }
217 
218                 /* otherwise we sleep until either the object we're waiting for
219                  * is done, or the fscache_object is congested */
220                 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
221                 init_wait(&wait);
222                 requeue = false;
223                 do {
224                         prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
225                         if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
226                                 break;
227 
228                         requeue = fscache_object_sleep_till_congested(&timeout);
229                 } while (timeout > 0 && !requeue);
230                 finish_wait(wq, &wait);
231 
232                 if (requeue &&
233                     test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
234                         _debug("queue OBJ%x behind OBJ%x after wait",
235                                object->fscache.debug_id,
236                                xobject->fscache.debug_id);
237                         goto requeue;
238                 }
239 
240                 if (timeout <= 0) {
241                         pr_err("\n");
242                         pr_err("Error: Overlong wait for old active object to go away\n");
243                         cachefiles_printk_object(object, xobject);
244                         goto requeue;
245                 }
246         }
247 
248         ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
249 
250         cache->cache.ops->put_object(&xobject->fscache);
251         goto try_again;
252 
253 requeue:
254         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
255         cache->cache.ops->put_object(&xobject->fscache);
256         _leave(" = -ETIMEDOUT");
257         return -ETIMEDOUT;
258 }
259 
260 /*
261  * Mark an object as being inactive.
262  */
263 void cachefiles_mark_object_inactive(struct cachefiles_cache *cache,
264                                      struct cachefiles_object *object)
265 {
266         write_lock(&cache->active_lock);
267         rb_erase(&object->active_node, &cache->active_nodes);
268         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
269         write_unlock(&cache->active_lock);
270 
271         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
272 
273         /* This object can now be culled, so we need to let the daemon know
274          * that there is something it can remove if it needs to.
275          */
276         atomic_long_add(d_backing_inode(object->dentry)->i_blocks,
277                         &cache->b_released);
278         if (atomic_inc_return(&cache->f_released))
279                 cachefiles_state_changed(cache);
280 }
281 
282 /*
283  * delete an object representation from the cache
284  * - file backed objects are unlinked
285  * - directory backed objects are stuffed into the graveyard for userspace to
286  *   delete
287  * - unlocks the directory mutex
288  */
289 static int cachefiles_bury_object(struct cachefiles_cache *cache,
290                                   struct dentry *dir,
291                                   struct dentry *rep,
292                                   bool preemptive,
293                                   enum fscache_why_object_killed why)
294 {
295         struct dentry *grave, *trap;
296         struct path path, path_to_graveyard;
297         char nbuffer[8 + 8 + 1];
298         int ret;
299 
300         _enter(",'%pd','%pd'", dir, rep);
301 
302         _debug("remove %p from %p", rep, dir);
303 
304         /* non-directories can just be unlinked */
305         if (!d_is_dir(rep)) {
306                 _debug("unlink stale object");
307 
308                 path.mnt = cache->mnt;
309                 path.dentry = dir;
310                 ret = security_path_unlink(&path, rep);
311                 if (ret < 0) {
312                         cachefiles_io_error(cache, "Unlink security error");
313                 } else {
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) get_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) {
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                 ret = vfs_rename(d_inode(dir), rep,
416                                  d_inode(cache->graveyard), grave, NULL, 0);
417                 if (ret != 0 && ret != -ENOMEM)
418                         cachefiles_io_error(cache,
419                                             "Rename failed with error %d", ret);
420 
421                 if (preemptive)
422                         cachefiles_mark_object_buried(cache, rep, why);
423         }
424 
425         unlock_rename(cache->graveyard, dir);
426         dput(grave);
427         _leave(" = 0");
428         return 0;
429 }
430 
431 /*
432  * delete an object representation from the cache
433  */
434 int cachefiles_delete_object(struct cachefiles_cache *cache,
435                              struct cachefiles_object *object)
436 {
437         struct dentry *dir;
438         int ret;
439 
440         _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
441 
442         ASSERT(object->dentry);
443         ASSERT(d_backing_inode(object->dentry));
444         ASSERT(object->dentry->d_parent);
445 
446         dir = dget_parent(object->dentry);
447 
448         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
449 
450         if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
451                 /* object allocation for the same key preemptively deleted this
452                  * object's file so that it could create its own file */
453                 _debug("object preemptively buried");
454                 inode_unlock(d_inode(dir));
455                 ret = 0;
456         } else {
457                 /* we need to check that our parent is _still_ our parent - it
458                  * may have been renamed */
459                 if (dir == object->dentry->d_parent) {
460                         ret = cachefiles_bury_object(cache, dir,
461                                                      object->dentry, false,
462                                                      FSCACHE_OBJECT_WAS_RETIRED);
463                 } else {
464                         /* it got moved, presumably by cachefilesd culling it,
465                          * so it's no longer in the key path and we can ignore
466                          * it */
467                         inode_unlock(d_inode(dir));
468                         ret = 0;
469                 }
470         }
471 
472         dput(dir);
473         _leave(" = %d", ret);
474         return ret;
475 }
476 
477 /*
478  * walk from the parent object to the child object through the backing
479  * filesystem, creating directories as we go
480  */
481 int cachefiles_walk_to_object(struct cachefiles_object *parent,
482                               struct cachefiles_object *object,
483                               const char *key,
484                               struct cachefiles_xattr *auxdata)
485 {
486         struct cachefiles_cache *cache;
487         struct dentry *dir, *next = NULL;
488         struct path path;
489         unsigned long start;
490         const char *name;
491         int ret, nlen;
492 
493         _enter("OBJ%x{%p},OBJ%x,%s,",
494                parent->fscache.debug_id, parent->dentry,
495                object->fscache.debug_id, key);
496 
497         cache = container_of(parent->fscache.cache,
498                              struct cachefiles_cache, cache);
499         path.mnt = cache->mnt;
500 
501         ASSERT(parent->dentry);
502         ASSERT(d_backing_inode(parent->dentry));
503 
504         if (!(d_is_dir(parent->dentry))) {
505                 // TODO: convert file to dir
506                 _leave("looking up in none directory");
507                 return -ENOBUFS;
508         }
509 
510         dir = dget(parent->dentry);
511 
512 advance:
513         /* attempt to transit the first directory component */
514         name = key;
515         nlen = strlen(key);
516 
517         /* key ends in a double NUL */
518         key = key + nlen + 1;
519         if (!*key)
520                 key = NULL;
521 
522 lookup_again:
523         /* search the current directory for the element name */
524         _debug("lookup '%s'", name);
525 
526         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
527 
528         start = jiffies;
529         next = lookup_one_len(name, dir, nlen);
530         cachefiles_hist(cachefiles_lookup_histogram, start);
531         if (IS_ERR(next))
532                 goto lookup_error;
533 
534         _debug("next -> %p %s", next, d_backing_inode(next) ? "positive" : "negative");
535 
536         if (!key)
537                 object->new = !d_backing_inode(next);
538 
539         /* if this element of the path doesn't exist, then the lookup phase
540          * failed, and we can release any readers in the certain knowledge that
541          * there's nothing for them to actually read */
542         if (d_is_negative(next))
543                 fscache_object_lookup_negative(&object->fscache);
544 
545         /* we need to create the object if it's negative */
546         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
547                 /* index objects and intervening tree levels must be subdirs */
548                 if (d_is_negative(next)) {
549                         ret = cachefiles_has_space(cache, 1, 0);
550                         if (ret < 0)
551                                 goto no_space_error;
552 
553                         path.dentry = dir;
554                         ret = security_path_mkdir(&path, next, 0);
555                         if (ret < 0)
556                                 goto create_error;
557                         start = jiffies;
558                         ret = vfs_mkdir(d_inode(dir), next, 0);
559                         cachefiles_hist(cachefiles_mkdir_histogram, start);
560                         if (ret < 0)
561                                 goto create_error;
562 
563                         ASSERT(d_backing_inode(next));
564 
565                         _debug("mkdir -> %p{%p{ino=%lu}}",
566                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
567 
568                 } else if (!d_can_lookup(next)) {
569                         pr_err("inode %lu is not a directory\n",
570                                d_backing_inode(next)->i_ino);
571                         ret = -ENOBUFS;
572                         goto error;
573                 }
574 
575         } else {
576                 /* non-index objects start out life as files */
577                 if (d_is_negative(next)) {
578                         ret = cachefiles_has_space(cache, 1, 0);
579                         if (ret < 0)
580                                 goto no_space_error;
581 
582                         path.dentry = dir;
583                         ret = security_path_mknod(&path, next, S_IFREG, 0);
584                         if (ret < 0)
585                                 goto create_error;
586                         start = jiffies;
587                         ret = vfs_create(d_inode(dir), next, S_IFREG, true);
588                         cachefiles_hist(cachefiles_create_histogram, start);
589                         if (ret < 0)
590                                 goto create_error;
591 
592                         ASSERT(d_backing_inode(next));
593 
594                         _debug("create -> %p{%p{ino=%lu}}",
595                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
596 
597                 } else if (!d_can_lookup(next) &&
598                            !d_is_reg(next)
599                            ) {
600                         pr_err("inode %lu is not a file or directory\n",
601                                d_backing_inode(next)->i_ino);
602                         ret = -ENOBUFS;
603                         goto error;
604                 }
605         }
606 
607         /* process the next component */
608         if (key) {
609                 _debug("advance");
610                 inode_unlock(d_inode(dir));
611                 dput(dir);
612                 dir = next;
613                 next = NULL;
614                 goto advance;
615         }
616 
617         /* we've found the object we were looking for */
618         object->dentry = next;
619 
620         /* if we've found that the terminal object exists, then we need to
621          * check its attributes and delete it if it's out of date */
622         if (!object->new) {
623                 _debug("validate '%pd'", next);
624 
625                 ret = cachefiles_check_object_xattr(object, auxdata);
626                 if (ret == -ESTALE) {
627                         /* delete the object (the deleter drops the directory
628                          * mutex) */
629                         object->dentry = NULL;
630 
631                         ret = cachefiles_bury_object(cache, dir, next, true,
632                                                      FSCACHE_OBJECT_IS_STALE);
633                         dput(next);
634                         next = NULL;
635 
636                         if (ret < 0)
637                                 goto delete_error;
638 
639                         _debug("redo lookup");
640                         fscache_object_retrying_stale(&object->fscache);
641                         goto lookup_again;
642                 }
643         }
644 
645         /* note that we're now using this object */
646         ret = cachefiles_mark_object_active(cache, object);
647 
648         inode_unlock(d_inode(dir));
649         dput(dir);
650         dir = NULL;
651 
652         if (ret == -ETIMEDOUT)
653                 goto mark_active_timed_out;
654 
655         _debug("=== OBTAINED_OBJECT ===");
656 
657         if (object->new) {
658                 /* attach data to a newly constructed terminal object */
659                 ret = cachefiles_set_object_xattr(object, auxdata);
660                 if (ret < 0)
661                         goto check_error;
662         } else {
663                 /* always update the atime on an object we've just looked up
664                  * (this is used to keep track of culling, and atimes are only
665                  * updated by read, write and readdir but not lookup or
666                  * open) */
667                 path.dentry = next;
668                 touch_atime(&path);
669         }
670 
671         /* open a file interface onto a data file */
672         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
673                 if (d_is_reg(object->dentry)) {
674                         const struct address_space_operations *aops;
675 
676                         ret = -EPERM;
677                         aops = d_backing_inode(object->dentry)->i_mapping->a_ops;
678                         if (!aops->bmap)
679                                 goto check_error;
680                         if (object->dentry->d_sb->s_blocksize > PAGE_SIZE)
681                                 goto check_error;
682 
683                         object->backer = object->dentry;
684                 } else {
685                         BUG(); // TODO: open file in data-class subdir
686                 }
687         }
688 
689         object->new = 0;
690         fscache_obtained_object(&object->fscache);
691 
692         _leave(" = 0 [%lu]", d_backing_inode(object->dentry)->i_ino);
693         return 0;
694 
695 no_space_error:
696         fscache_object_mark_killed(&object->fscache, FSCACHE_OBJECT_NO_SPACE);
697 create_error:
698         _debug("create error %d", ret);
699         if (ret == -EIO)
700                 cachefiles_io_error(cache, "Create/mkdir failed");
701         goto error;
702 
703 mark_active_timed_out:
704         _debug("mark active timed out");
705         goto release_dentry;
706 
707 check_error:
708         _debug("check error %d", ret);
709         cachefiles_mark_object_inactive(cache, object);
710 release_dentry:
711         dput(object->dentry);
712         object->dentry = NULL;
713         goto error_out;
714 
715 delete_error:
716         _debug("delete error %d", ret);
717         goto error_out2;
718 
719 lookup_error:
720         _debug("lookup error %ld", PTR_ERR(next));
721         ret = PTR_ERR(next);
722         if (ret == -EIO)
723                 cachefiles_io_error(cache, "Lookup failed");
724         next = NULL;
725 error:
726         inode_unlock(d_inode(dir));
727         dput(next);
728 error_out2:
729         dput(dir);
730 error_out:
731         _leave(" = error %d", -ret);
732         return ret;
733 }
734 
735 /*
736  * get a subdirectory
737  */
738 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
739                                         struct dentry *dir,
740                                         const char *dirname)
741 {
742         struct dentry *subdir;
743         unsigned long start;
744         struct path path;
745         int ret;
746 
747         _enter(",,%s", dirname);
748 
749         /* search the current directory for the element name */
750         inode_lock(d_inode(dir));
751 
752         start = jiffies;
753         subdir = lookup_one_len(dirname, dir, strlen(dirname));
754         cachefiles_hist(cachefiles_lookup_histogram, start);
755         if (IS_ERR(subdir)) {
756                 if (PTR_ERR(subdir) == -ENOMEM)
757                         goto nomem_d_alloc;
758                 goto lookup_error;
759         }
760 
761         _debug("subdir -> %p %s",
762                subdir, d_backing_inode(subdir) ? "positive" : "negative");
763 
764         /* we need to create the subdir if it doesn't exist yet */
765         if (d_is_negative(subdir)) {
766                 ret = cachefiles_has_space(cache, 1, 0);
767                 if (ret < 0)
768                         goto mkdir_error;
769 
770                 _debug("attempt mkdir");
771 
772                 path.mnt = cache->mnt;
773                 path.dentry = dir;
774                 ret = security_path_mkdir(&path, subdir, 0700);
775                 if (ret < 0)
776                         goto mkdir_error;
777                 ret = vfs_mkdir(d_inode(dir), subdir, 0700);
778                 if (ret < 0)
779                         goto mkdir_error;
780 
781                 ASSERT(d_backing_inode(subdir));
782 
783                 _debug("mkdir -> %p{%p{ino=%lu}}",
784                        subdir,
785                        d_backing_inode(subdir),
786                        d_backing_inode(subdir)->i_ino);
787         }
788 
789         inode_unlock(d_inode(dir));
790 
791         /* we need to make sure the subdir is a directory */
792         ASSERT(d_backing_inode(subdir));
793 
794         if (!d_can_lookup(subdir)) {
795                 pr_err("%s is not a directory\n", dirname);
796                 ret = -EIO;
797                 goto check_error;
798         }
799 
800         ret = -EPERM;
801         if (!d_backing_inode(subdir)->i_op->setxattr ||
802             !d_backing_inode(subdir)->i_op->getxattr ||
803             !d_backing_inode(subdir)->i_op->lookup ||
804             !d_backing_inode(subdir)->i_op->mkdir ||
805             !d_backing_inode(subdir)->i_op->create ||
806             (!d_backing_inode(subdir)->i_op->rename &&
807              !d_backing_inode(subdir)->i_op->rename2) ||
808             !d_backing_inode(subdir)->i_op->rmdir ||
809             !d_backing_inode(subdir)->i_op->unlink)
810                 goto check_error;
811 
812         _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
813         return subdir;
814 
815 check_error:
816         dput(subdir);
817         _leave(" = %d [check]", ret);
818         return ERR_PTR(ret);
819 
820 mkdir_error:
821         inode_unlock(d_inode(dir));
822         dput(subdir);
823         pr_err("mkdir %s failed with error %d\n", dirname, ret);
824         return ERR_PTR(ret);
825 
826 lookup_error:
827         inode_unlock(d_inode(dir));
828         ret = PTR_ERR(subdir);
829         pr_err("Lookup %s failed with error %d\n", dirname, ret);
830         return ERR_PTR(ret);
831 
832 nomem_d_alloc:
833         inode_unlock(d_inode(dir));
834         _leave(" = -ENOMEM");
835         return ERR_PTR(-ENOMEM);
836 }
837 
838 /*
839  * find out if an object is in use or not
840  * - if finds object and it's not in use:
841  *   - returns a pointer to the object and a reference on it
842  *   - returns with the directory locked
843  */
844 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
845                                               struct dentry *dir,
846                                               char *filename)
847 {
848         struct cachefiles_object *object;
849         struct rb_node *_n;
850         struct dentry *victim;
851         unsigned long start;
852         int ret;
853 
854         //_enter(",%pd/,%s",
855         //       dir, filename);
856 
857         /* look up the victim */
858         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
859 
860         start = jiffies;
861         victim = lookup_one_len(filename, dir, strlen(filename));
862         cachefiles_hist(cachefiles_lookup_histogram, start);
863         if (IS_ERR(victim))
864                 goto lookup_error;
865 
866         //_debug("victim -> %p %s",
867         //       victim, d_backing_inode(victim) ? "positive" : "negative");
868 
869         /* if the object is no longer there then we probably retired the object
870          * at the netfs's request whilst the cull was in progress
871          */
872         if (d_is_negative(victim)) {
873                 inode_unlock(d_inode(dir));
874                 dput(victim);
875                 _leave(" = -ENOENT [absent]");
876                 return ERR_PTR(-ENOENT);
877         }
878 
879         /* check to see if we're using this object */
880         read_lock(&cache->active_lock);
881 
882         _n = cache->active_nodes.rb_node;
883 
884         while (_n) {
885                 object = rb_entry(_n, struct cachefiles_object, active_node);
886 
887                 if (object->dentry > victim)
888                         _n = _n->rb_left;
889                 else if (object->dentry < victim)
890                         _n = _n->rb_right;
891                 else
892                         goto object_in_use;
893         }
894 
895         read_unlock(&cache->active_lock);
896 
897         //_leave(" = %p", victim);
898         return victim;
899 
900 object_in_use:
901         read_unlock(&cache->active_lock);
902         inode_unlock(d_inode(dir));
903         dput(victim);
904         //_leave(" = -EBUSY [in use]");
905         return ERR_PTR(-EBUSY);
906 
907 lookup_error:
908         inode_unlock(d_inode(dir));
909         ret = PTR_ERR(victim);
910         if (ret == -ENOENT) {
911                 /* file or dir now absent - probably retired by netfs */
912                 _leave(" = -ESTALE [absent]");
913                 return ERR_PTR(-ESTALE);
914         }
915 
916         if (ret == -EIO) {
917                 cachefiles_io_error(cache, "Lookup failed");
918         } else if (ret != -ENOMEM) {
919                 pr_err("Internal error: %d\n", ret);
920                 ret = -EIO;
921         }
922 
923         _leave(" = %d", ret);
924         return ERR_PTR(ret);
925 }
926 
927 /*
928  * cull an object if it's not in use
929  * - called only by cache manager daemon
930  */
931 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
932                     char *filename)
933 {
934         struct dentry *victim;
935         int ret;
936 
937         _enter(",%pd/,%s", dir, filename);
938 
939         victim = cachefiles_check_active(cache, dir, filename);
940         if (IS_ERR(victim))
941                 return PTR_ERR(victim);
942 
943         _debug("victim -> %p %s",
944                victim, d_backing_inode(victim) ? "positive" : "negative");
945 
946         /* okay... the victim is not being used so we can cull it
947          * - start by marking it as stale
948          */
949         _debug("victim is cullable");
950 
951         ret = cachefiles_remove_object_xattr(cache, victim);
952         if (ret < 0)
953                 goto error_unlock;
954 
955         /*  actually remove the victim (drops the dir mutex) */
956         _debug("bury");
957 
958         ret = cachefiles_bury_object(cache, dir, victim, false,
959                                      FSCACHE_OBJECT_WAS_CULLED);
960         if (ret < 0)
961                 goto error;
962 
963         dput(victim);
964         _leave(" = 0");
965         return 0;
966 
967 error_unlock:
968         inode_unlock(d_inode(dir));
969 error:
970         dput(victim);
971         if (ret == -ENOENT) {
972                 /* file or dir now absent - probably retired by netfs */
973                 _leave(" = -ESTALE [absent]");
974                 return -ESTALE;
975         }
976 
977         if (ret != -ENOMEM) {
978                 pr_err("Internal error: %d\n", ret);
979                 ret = -EIO;
980         }
981 
982         _leave(" = %d", ret);
983         return ret;
984 }
985 
986 /*
987  * find out if an object is in use or not
988  * - called only by cache manager daemon
989  * - returns -EBUSY or 0 to indicate whether an object is in use or not
990  */
991 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
992                             char *filename)
993 {
994         struct dentry *victim;
995 
996         //_enter(",%pd/,%s",
997         //       dir, filename);
998 
999         victim = cachefiles_check_active(cache, dir, filename);
1000         if (IS_ERR(victim))
1001                 return PTR_ERR(victim);
1002 
1003         inode_unlock(d_inode(dir));
1004         dput(victim);
1005         //_leave(" = 0");
1006         return 0;
1007 }
1008 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp