1 /* CacheFiles path walking and related routines
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
12 #include <linux/module.h>
13 #include <linux/sched.h>
14 #include <linux/file.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>
24 #define CACHEFILES_KEYBUF_SIZE 512
27 * dump debugging info about an object
30 void __cachefiles_printk_object(struct cachefiles_object *object,
34 struct fscache_cookie *cookie;
35 unsigned keylen, loop;
37 printk(KERN_ERR "%sobject: OBJ%x\n",
38 prefix, object->fscache.debug_id);
39 printk(KERN_ERR "%sobjstate=%s fl=%lx swfl=%lx ev=%lx[%lx]\n",
40 prefix, fscache_object_states[object->fscache.state],
41 object->fscache.flags, object->fscache.work.flags,
42 object->fscache.events,
43 object->fscache.event_mask & FSCACHE_OBJECT_EVENTS_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);
50 spin_lock(&object->fscache.lock);
51 cookie = object->fscache.cookie;
53 printk(KERN_ERR "%scookie=%p [pr=%p nd=%p fl=%lx]\n",
55 object->fscache.cookie,
56 object->fscache.cookie->parent,
57 object->fscache.cookie->netfs_data,
58 object->fscache.cookie->flags);
60 keylen = cookie->def->get_key(cookie->netfs_data, keybuf,
61 CACHEFILES_KEYBUF_SIZE);
65 printk(KERN_ERR "%scookie=NULL\n", prefix);
68 spin_unlock(&object->fscache.lock);
71 printk(KERN_ERR "%skey=[%u] '", prefix, keylen);
72 for (loop = 0; loop < keylen; loop++)
73 printk("%02x", keybuf[loop]);
79 * dump debugging info about a pair of objects
81 static noinline void cachefiles_printk_object(struct cachefiles_object *object,
82 struct cachefiles_object *xobject)
86 keybuf = kmalloc(CACHEFILES_KEYBUF_SIZE, GFP_NOIO);
88 __cachefiles_printk_object(object, "", keybuf);
90 __cachefiles_printk_object(xobject, "x", keybuf);
95 * record the fact that an object is now active
97 static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
98 struct cachefiles_object *object)
100 struct cachefiles_object *xobject;
101 struct rb_node **_p, *_parent = NULL;
102 struct dentry *dentry;
104 _enter(",%p", object);
107 write_lock(&cache->active_lock);
109 if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
110 printk(KERN_ERR "CacheFiles: Error: Object already active\n");
111 cachefiles_printk_object(object, NULL);
115 dentry = object->dentry;
116 _p = &cache->active_nodes.rb_node;
119 xobject = rb_entry(_parent,
120 struct cachefiles_object, active_node);
122 ASSERT(xobject != object);
124 if (xobject->dentry > dentry)
125 _p = &(*_p)->rb_left;
126 else if (xobject->dentry < dentry)
127 _p = &(*_p)->rb_right;
129 goto wait_for_old_object;
132 rb_link_node(&object->active_node, _parent, _p);
133 rb_insert_color(&object->active_node, &cache->active_nodes);
135 write_unlock(&cache->active_lock);
139 /* an old object from a previous incarnation is hogging the slot - we
140 * need to wait for it to be destroyed */
142 if (xobject->fscache.state < FSCACHE_OBJECT_DYING) {
143 printk(KERN_ERR "\n");
144 printk(KERN_ERR "CacheFiles: Error:"
145 " Unexpected object collision\n");
146 cachefiles_printk_object(object, xobject);
149 atomic_inc(&xobject->usage);
150 write_unlock(&cache->active_lock);
152 if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
153 wait_queue_head_t *wq;
155 signed long timeout = 60 * HZ;
159 /* if the object we're waiting for is queued for processing,
160 * then just put ourselves on the queue behind it */
161 if (slow_work_is_queued(&xobject->fscache.work)) {
162 _debug("queue OBJ%x behind OBJ%x immediately",
163 object->fscache.debug_id,
164 xobject->fscache.debug_id);
168 /* otherwise we sleep until either the object we're waiting for
169 * is done, or the slow-work facility wants the thread back to
171 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
175 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
176 if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
178 requeue = slow_work_sleep_till_thread_needed(
179 &object->fscache.work, &timeout);
180 } while (timeout > 0 && !requeue);
181 finish_wait(wq, &wait);
184 test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
185 _debug("queue OBJ%x behind OBJ%x after wait",
186 object->fscache.debug_id,
187 xobject->fscache.debug_id);
192 printk(KERN_ERR "\n");
193 printk(KERN_ERR "CacheFiles: Error: Overlong"
194 " wait for old active object to go away\n");
195 cachefiles_printk_object(object, xobject);
200 ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
202 cache->cache.ops->put_object(&xobject->fscache);
206 clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
207 cache->cache.ops->put_object(&xobject->fscache);
208 _leave(" = -ETIMEDOUT");
213 * delete an object representation from the cache
214 * - file backed objects are unlinked
215 * - directory backed objects are stuffed into the graveyard for userspace to
217 * - unlocks the directory mutex
219 static int cachefiles_bury_object(struct cachefiles_cache *cache,
223 struct dentry *grave, *trap;
224 char nbuffer[8 + 8 + 1];
227 _enter(",'%*.*s','%*.*s'",
228 dir->d_name.len, dir->d_name.len, dir->d_name.name,
229 rep->d_name.len, rep->d_name.len, rep->d_name.name);
231 /* non-directories can just be unlinked */
232 if (!S_ISDIR(rep->d_inode->i_mode)) {
233 _debug("unlink stale object");
234 ret = vfs_unlink(dir->d_inode, rep);
236 mutex_unlock(&dir->d_inode->i_mutex);
239 cachefiles_io_error(cache, "Unlink failed");
241 _leave(" = %d", ret);
245 /* directories have to be moved to the graveyard */
246 _debug("move stale object to graveyard");
247 mutex_unlock(&dir->d_inode->i_mutex);
250 /* first step is to make up a grave dentry in the graveyard */
251 sprintf(nbuffer, "%08x%08x",
252 (uint32_t) get_seconds(),
253 (uint32_t) atomic_inc_return(&cache->gravecounter));
255 /* do the multiway lock magic */
256 trap = lock_rename(cache->graveyard, dir);
258 /* do some checks before getting the grave dentry */
259 if (rep->d_parent != dir) {
260 /* the entry was probably culled when we dropped the parent dir
262 unlock_rename(cache->graveyard, dir);
263 _leave(" = 0 [culled?]");
267 if (!S_ISDIR(cache->graveyard->d_inode->i_mode)) {
268 unlock_rename(cache->graveyard, dir);
269 cachefiles_io_error(cache, "Graveyard no longer a directory");
274 unlock_rename(cache->graveyard, dir);
275 cachefiles_io_error(cache, "May not make directory loop");
279 if (d_mountpoint(rep)) {
280 unlock_rename(cache->graveyard, dir);
281 cachefiles_io_error(cache, "Mountpoint in cache");
285 grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
287 unlock_rename(cache->graveyard, dir);
289 if (PTR_ERR(grave) == -ENOMEM) {
290 _leave(" = -ENOMEM");
294 cachefiles_io_error(cache, "Lookup error %ld",
299 if (grave->d_inode) {
300 unlock_rename(cache->graveyard, dir);
307 if (d_mountpoint(grave)) {
308 unlock_rename(cache->graveyard, dir);
310 cachefiles_io_error(cache, "Mountpoint in graveyard");
314 /* target should not be an ancestor of source */
316 unlock_rename(cache->graveyard, dir);
318 cachefiles_io_error(cache, "May not make directory loop");
322 /* attempt the rename */
323 ret = vfs_rename(dir->d_inode, rep, cache->graveyard->d_inode, grave);
324 if (ret != 0 && ret != -ENOMEM)
325 cachefiles_io_error(cache, "Rename failed with error %d", ret);
327 unlock_rename(cache->graveyard, dir);
334 * delete an object representation from the cache
336 int cachefiles_delete_object(struct cachefiles_cache *cache,
337 struct cachefiles_object *object)
342 _enter(",{%p}", object->dentry);
344 ASSERT(object->dentry);
345 ASSERT(object->dentry->d_inode);
346 ASSERT(object->dentry->d_parent);
348 dir = dget_parent(object->dentry);
350 mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
352 /* we need to check that our parent is _still_ our parent - it may have
354 if (dir == object->dentry->d_parent) {
355 ret = cachefiles_bury_object(cache, dir, object->dentry);
357 /* it got moved, presumably by cachefilesd culling it, so it's
358 * no longer in the key path and we can ignore it */
359 mutex_unlock(&dir->d_inode->i_mutex);
364 _leave(" = %d", ret);
369 * walk from the parent object to the child object through the backing
370 * filesystem, creating directories as we go
372 int cachefiles_walk_to_object(struct cachefiles_object *parent,
373 struct cachefiles_object *object,
375 struct cachefiles_xattr *auxdata)
377 struct cachefiles_cache *cache;
378 struct dentry *dir, *next = NULL;
383 _enter("{%p},,%s,", parent->dentry, key);
385 cache = container_of(parent->fscache.cache,
386 struct cachefiles_cache, cache);
388 ASSERT(parent->dentry);
389 ASSERT(parent->dentry->d_inode);
391 if (!(S_ISDIR(parent->dentry->d_inode->i_mode))) {
392 // TODO: convert file to dir
393 _leave("looking up in none directory");
397 dir = dget(parent->dentry);
400 /* attempt to transit the first directory component */
404 /* key ends in a double NUL */
405 key = key + nlen + 1;
410 /* search the current directory for the element name */
411 _debug("lookup '%s'", name);
413 mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
416 next = lookup_one_len(name, dir, nlen);
417 cachefiles_hist(cachefiles_lookup_histogram, start);
421 _debug("next -> %p %s", next, next->d_inode ? "positive" : "negative");
424 object->new = !next->d_inode;
426 /* if this element of the path doesn't exist, then the lookup phase
427 * failed, and we can release any readers in the certain knowledge that
428 * there's nothing for them to actually read */
430 fscache_object_lookup_negative(&object->fscache);
432 /* we need to create the object if it's negative */
433 if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
434 /* index objects and intervening tree levels must be subdirs */
435 if (!next->d_inode) {
436 ret = cachefiles_has_space(cache, 1, 0);
441 ret = vfs_mkdir(dir->d_inode, next, 0);
442 cachefiles_hist(cachefiles_mkdir_histogram, start);
446 ASSERT(next->d_inode);
448 _debug("mkdir -> %p{%p{ino=%lu}}",
449 next, next->d_inode, next->d_inode->i_ino);
451 } else if (!S_ISDIR(next->d_inode->i_mode)) {
452 kerror("inode %lu is not a directory",
453 next->d_inode->i_ino);
459 /* non-index objects start out life as files */
460 if (!next->d_inode) {
461 ret = cachefiles_has_space(cache, 1, 0);
466 ret = vfs_create(dir->d_inode, next, S_IFREG, NULL);
467 cachefiles_hist(cachefiles_create_histogram, start);
471 ASSERT(next->d_inode);
473 _debug("create -> %p{%p{ino=%lu}}",
474 next, next->d_inode, next->d_inode->i_ino);
476 } else if (!S_ISDIR(next->d_inode->i_mode) &&
477 !S_ISREG(next->d_inode->i_mode)
479 kerror("inode %lu is not a file or directory",
480 next->d_inode->i_ino);
486 /* process the next component */
489 mutex_unlock(&dir->d_inode->i_mutex);
496 /* we've found the object we were looking for */
497 object->dentry = next;
499 /* if we've found that the terminal object exists, then we need to
500 * check its attributes and delete it if it's out of date */
502 _debug("validate '%*.*s'",
503 next->d_name.len, next->d_name.len, next->d_name.name);
505 ret = cachefiles_check_object_xattr(object, auxdata);
506 if (ret == -ESTALE) {
507 /* delete the object (the deleter drops the directory
509 object->dentry = NULL;
511 ret = cachefiles_bury_object(cache, dir, next);
518 _debug("redo lookup");
523 /* note that we're now using this object */
524 ret = cachefiles_mark_object_active(cache, object);
526 mutex_unlock(&dir->d_inode->i_mutex);
530 if (ret == -ETIMEDOUT)
531 goto mark_active_timed_out;
533 _debug("=== OBTAINED_OBJECT ===");
536 /* attach data to a newly constructed terminal object */
537 ret = cachefiles_set_object_xattr(object, auxdata);
541 /* always update the atime on an object we've just looked up
542 * (this is used to keep track of culling, and atimes are only
543 * updated by read, write and readdir but not lookup or
545 touch_atime(cache->mnt, next);
548 /* open a file interface onto a data file */
549 if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
550 if (S_ISREG(object->dentry->d_inode->i_mode)) {
551 const struct address_space_operations *aops;
554 aops = object->dentry->d_inode->i_mapping->a_ops;
558 object->backer = object->dentry;
560 BUG(); // TODO: open file in data-class subdir
565 fscache_obtained_object(&object->fscache);
567 _leave(" = 0 [%lu]", object->dentry->d_inode->i_ino);
571 _debug("create error %d", ret);
573 cachefiles_io_error(cache, "Create/mkdir failed");
576 mark_active_timed_out:
577 _debug("mark active timed out");
581 _debug("check error %d", ret);
582 write_lock(&cache->active_lock);
583 rb_erase(&object->active_node, &cache->active_nodes);
584 clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
585 wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
586 write_unlock(&cache->active_lock);
588 dput(object->dentry);
589 object->dentry = NULL;
593 _debug("delete error %d", ret);
597 _debug("lookup error %ld", PTR_ERR(next));
600 cachefiles_io_error(cache, "Lookup failed");
603 mutex_unlock(&dir->d_inode->i_mutex);
608 _leave(" = error %d", -ret);
615 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
619 struct dentry *subdir;
623 _enter(",,%s", dirname);
625 /* search the current directory for the element name */
626 mutex_lock(&dir->d_inode->i_mutex);
629 subdir = lookup_one_len(dirname, dir, strlen(dirname));
630 cachefiles_hist(cachefiles_lookup_histogram, start);
631 if (IS_ERR(subdir)) {
632 if (PTR_ERR(subdir) == -ENOMEM)
637 _debug("subdir -> %p %s",
638 subdir, subdir->d_inode ? "positive" : "negative");
640 /* we need to create the subdir if it doesn't exist yet */
641 if (!subdir->d_inode) {
642 ret = cachefiles_has_space(cache, 1, 0);
646 _debug("attempt mkdir");
648 ret = vfs_mkdir(dir->d_inode, subdir, 0700);
652 ASSERT(subdir->d_inode);
654 _debug("mkdir -> %p{%p{ino=%lu}}",
657 subdir->d_inode->i_ino);
660 mutex_unlock(&dir->d_inode->i_mutex);
662 /* we need to make sure the subdir is a directory */
663 ASSERT(subdir->d_inode);
665 if (!S_ISDIR(subdir->d_inode->i_mode)) {
666 kerror("%s is not a directory", dirname);
672 if (!subdir->d_inode->i_op ||
673 !subdir->d_inode->i_op->setxattr ||
674 !subdir->d_inode->i_op->getxattr ||
675 !subdir->d_inode->i_op->lookup ||
676 !subdir->d_inode->i_op->mkdir ||
677 !subdir->d_inode->i_op->create ||
678 !subdir->d_inode->i_op->rename ||
679 !subdir->d_inode->i_op->rmdir ||
680 !subdir->d_inode->i_op->unlink)
683 _leave(" = [%lu]", subdir->d_inode->i_ino);
688 _leave(" = %d [check]", ret);
692 mutex_unlock(&dir->d_inode->i_mutex);
694 kerror("mkdir %s failed with error %d", dirname, ret);
698 mutex_unlock(&dir->d_inode->i_mutex);
699 ret = PTR_ERR(subdir);
700 kerror("Lookup %s failed with error %d", dirname, ret);
704 mutex_unlock(&dir->d_inode->i_mutex);
705 _leave(" = -ENOMEM");
706 return ERR_PTR(-ENOMEM);
710 * find out if an object is in use or not
711 * - if finds object and it's not in use:
712 * - returns a pointer to the object and a reference on it
713 * - returns with the directory locked
715 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
719 struct cachefiles_object *object;
721 struct dentry *victim;
725 //_enter(",%*.*s/,%s",
726 // dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
728 /* look up the victim */
729 mutex_lock_nested(&dir->d_inode->i_mutex, 1);
732 victim = lookup_one_len(filename, dir, strlen(filename));
733 cachefiles_hist(cachefiles_lookup_histogram, start);
737 //_debug("victim -> %p %s",
738 // victim, victim->d_inode ? "positive" : "negative");
740 /* if the object is no longer there then we probably retired the object
741 * at the netfs's request whilst the cull was in progress
743 if (!victim->d_inode) {
744 mutex_unlock(&dir->d_inode->i_mutex);
746 _leave(" = -ENOENT [absent]");
747 return ERR_PTR(-ENOENT);
750 /* check to see if we're using this object */
751 read_lock(&cache->active_lock);
753 _n = cache->active_nodes.rb_node;
756 object = rb_entry(_n, struct cachefiles_object, active_node);
758 if (object->dentry > victim)
760 else if (object->dentry < victim)
766 read_unlock(&cache->active_lock);
768 //_leave(" = %p", victim);
772 read_unlock(&cache->active_lock);
773 mutex_unlock(&dir->d_inode->i_mutex);
775 //_leave(" = -EBUSY [in use]");
776 return ERR_PTR(-EBUSY);
779 mutex_unlock(&dir->d_inode->i_mutex);
780 ret = PTR_ERR(victim);
781 if (ret == -ENOENT) {
782 /* file or dir now absent - probably retired by netfs */
783 _leave(" = -ESTALE [absent]");
784 return ERR_PTR(-ESTALE);
788 cachefiles_io_error(cache, "Lookup failed");
789 } else if (ret != -ENOMEM) {
790 kerror("Internal error: %d", ret);
794 _leave(" = %d", ret);
799 * cull an object if it's not in use
800 * - called only by cache manager daemon
802 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
805 struct dentry *victim;
809 dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
811 victim = cachefiles_check_active(cache, dir, filename);
813 return PTR_ERR(victim);
815 _debug("victim -> %p %s",
816 victim, victim->d_inode ? "positive" : "negative");
818 /* okay... the victim is not being used so we can cull it
819 * - start by marking it as stale
821 _debug("victim is cullable");
823 ret = cachefiles_remove_object_xattr(cache, victim);
827 /* actually remove the victim (drops the dir mutex) */
830 ret = cachefiles_bury_object(cache, dir, victim);
839 mutex_unlock(&dir->d_inode->i_mutex);
842 if (ret == -ENOENT) {
843 /* file or dir now absent - probably retired by netfs */
844 _leave(" = -ESTALE [absent]");
848 if (ret != -ENOMEM) {
849 kerror("Internal error: %d", ret);
853 _leave(" = %d", ret);
858 * find out if an object is in use or not
859 * - called only by cache manager daemon
860 * - returns -EBUSY or 0 to indicate whether an object is in use or not
862 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
865 struct dentry *victim;
867 //_enter(",%*.*s/,%s",
868 // dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
870 victim = cachefiles_check_active(cache, dir, filename);
872 return PTR_ERR(victim);
874 mutex_unlock(&dir->d_inode->i_mutex);