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