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TOMOYO Linux Cross Reference
Linux/fs/ocfs2/uptodate.c

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  1 /* -*- mode: c; c-basic-offset: 8; -*-
  2  * vim: noexpandtab sw=8 ts=8 sts=0:
  3  *
  4  * uptodate.c
  5  *
  6  * Tracking the up-to-date-ness of a local buffer_head with respect to
  7  * the cluster.
  8  *
  9  * Copyright (C) 2002, 2004, 2005 Oracle.  All rights reserved.
 10  *
 11  * This program is free software; you can redistribute it and/or
 12  * modify it under the terms of the GNU General Public
 13  * License as published by the Free Software Foundation; either
 14  * version 2 of the License, or (at your option) any later version.
 15  *
 16  * This program is distributed in the hope that it will be useful,
 17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 19  * General Public License for more details.
 20  *
 21  * You should have received a copy of the GNU General Public
 22  * License along with this program; if not, write to the
 23  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 24  * Boston, MA 021110-1307, USA.
 25  *
 26  * Standard buffer head caching flags (uptodate, etc) are insufficient
 27  * in a clustered environment - a buffer may be marked up to date on
 28  * our local node but could have been modified by another cluster
 29  * member. As a result an additional (and performant) caching scheme
 30  * is required. A further requirement is that we consume as little
 31  * memory as possible - we never pin buffer_head structures in order
 32  * to cache them.
 33  *
 34  * We track the existence of up to date buffers on the inodes which
 35  * are associated with them. Because we don't want to pin
 36  * buffer_heads, this is only a (strong) hint and several other checks
 37  * are made in the I/O path to ensure that we don't use a stale or
 38  * invalid buffer without going to disk:
 39  *      - buffer_jbd is used liberally - if a bh is in the journal on
 40  *        this node then it *must* be up to date.
 41  *      - the standard buffer_uptodate() macro is used to detect buffers
 42  *        which may be invalid (even if we have an up to date tracking
 43  *        item for them)
 44  *
 45  * For a full understanding of how this code works together, one
 46  * should read the callers in dlmglue.c, the I/O functions in
 47  * buffer_head_io.c and ocfs2_journal_access in journal.c
 48  */
 49 
 50 #include <linux/fs.h>
 51 #include <linux/types.h>
 52 #include <linux/slab.h>
 53 #include <linux/highmem.h>
 54 #include <linux/buffer_head.h>
 55 #include <linux/rbtree.h>
 56 
 57 #include <cluster/masklog.h>
 58 
 59 #include "ocfs2.h"
 60 
 61 #include "inode.h"
 62 #include "uptodate.h"
 63 #include "ocfs2_trace.h"
 64 
 65 struct ocfs2_meta_cache_item {
 66         struct rb_node  c_node;
 67         sector_t        c_block;
 68 };
 69 
 70 static struct kmem_cache *ocfs2_uptodate_cachep;
 71 
 72 u64 ocfs2_metadata_cache_owner(struct ocfs2_caching_info *ci)
 73 {
 74         BUG_ON(!ci || !ci->ci_ops);
 75 
 76         return ci->ci_ops->co_owner(ci);
 77 }
 78 
 79 struct super_block *ocfs2_metadata_cache_get_super(struct ocfs2_caching_info *ci)
 80 {
 81         BUG_ON(!ci || !ci->ci_ops);
 82 
 83         return ci->ci_ops->co_get_super(ci);
 84 }
 85 
 86 static void ocfs2_metadata_cache_lock(struct ocfs2_caching_info *ci)
 87 {
 88         BUG_ON(!ci || !ci->ci_ops);
 89 
 90         ci->ci_ops->co_cache_lock(ci);
 91 }
 92 
 93 static void ocfs2_metadata_cache_unlock(struct ocfs2_caching_info *ci)
 94 {
 95         BUG_ON(!ci || !ci->ci_ops);
 96 
 97         ci->ci_ops->co_cache_unlock(ci);
 98 }
 99 
100 void ocfs2_metadata_cache_io_lock(struct ocfs2_caching_info *ci)
101 {
102         BUG_ON(!ci || !ci->ci_ops);
103 
104         ci->ci_ops->co_io_lock(ci);
105 }
106 
107 void ocfs2_metadata_cache_io_unlock(struct ocfs2_caching_info *ci)
108 {
109         BUG_ON(!ci || !ci->ci_ops);
110 
111         ci->ci_ops->co_io_unlock(ci);
112 }
113 
114 
115 static void ocfs2_metadata_cache_reset(struct ocfs2_caching_info *ci,
116                                        int clear)
117 {
118         ci->ci_flags |= OCFS2_CACHE_FL_INLINE;
119         ci->ci_num_cached = 0;
120 
121         if (clear) {
122                 ci->ci_created_trans = 0;
123                 ci->ci_last_trans = 0;
124         }
125 }
126 
127 void ocfs2_metadata_cache_init(struct ocfs2_caching_info *ci,
128                                const struct ocfs2_caching_operations *ops)
129 {
130         BUG_ON(!ops);
131 
132         ci->ci_ops = ops;
133         ocfs2_metadata_cache_reset(ci, 1);
134 }
135 
136 void ocfs2_metadata_cache_exit(struct ocfs2_caching_info *ci)
137 {
138         ocfs2_metadata_cache_purge(ci);
139         ocfs2_metadata_cache_reset(ci, 1);
140 }
141 
142 
143 /* No lock taken here as 'root' is not expected to be visible to other
144  * processes. */
145 static unsigned int ocfs2_purge_copied_metadata_tree(struct rb_root *root)
146 {
147         unsigned int purged = 0;
148         struct rb_node *node;
149         struct ocfs2_meta_cache_item *item;
150 
151         while ((node = rb_last(root)) != NULL) {
152                 item = rb_entry(node, struct ocfs2_meta_cache_item, c_node);
153 
154                 trace_ocfs2_purge_copied_metadata_tree(
155                                         (unsigned long long) item->c_block);
156 
157                 rb_erase(&item->c_node, root);
158                 kmem_cache_free(ocfs2_uptodate_cachep, item);
159 
160                 purged++;
161         }
162         return purged;
163 }
164 
165 /* Called from locking and called from ocfs2_clear_inode. Dump the
166  * cache for a given inode.
167  *
168  * This function is a few more lines longer than necessary due to some
169  * accounting done here, but I think it's worth tracking down those
170  * bugs sooner -- Mark */
171 void ocfs2_metadata_cache_purge(struct ocfs2_caching_info *ci)
172 {
173         unsigned int tree, to_purge, purged;
174         struct rb_root root = RB_ROOT;
175 
176         BUG_ON(!ci || !ci->ci_ops);
177 
178         ocfs2_metadata_cache_lock(ci);
179         tree = !(ci->ci_flags & OCFS2_CACHE_FL_INLINE);
180         to_purge = ci->ci_num_cached;
181 
182         trace_ocfs2_metadata_cache_purge(
183                 (unsigned long long)ocfs2_metadata_cache_owner(ci),
184                 to_purge, tree);
185 
186         /* If we're a tree, save off the root so that we can safely
187          * initialize the cache. We do the work to free tree members
188          * without the spinlock. */
189         if (tree)
190                 root = ci->ci_cache.ci_tree;
191 
192         ocfs2_metadata_cache_reset(ci, 0);
193         ocfs2_metadata_cache_unlock(ci);
194 
195         purged = ocfs2_purge_copied_metadata_tree(&root);
196         /* If possible, track the number wiped so that we can more
197          * easily detect counting errors. Unfortunately, this is only
198          * meaningful for trees. */
199         if (tree && purged != to_purge)
200                 mlog(ML_ERROR, "Owner %llu, count = %u, purged = %u\n",
201                      (unsigned long long)ocfs2_metadata_cache_owner(ci),
202                      to_purge, purged);
203 }
204 
205 /* Returns the index in the cache array, -1 if not found.
206  * Requires ip_lock. */
207 static int ocfs2_search_cache_array(struct ocfs2_caching_info *ci,
208                                     sector_t item)
209 {
210         int i;
211 
212         for (i = 0; i < ci->ci_num_cached; i++) {
213                 if (item == ci->ci_cache.ci_array[i])
214                         return i;
215         }
216 
217         return -1;
218 }
219 
220 /* Returns the cache item if found, otherwise NULL.
221  * Requires ip_lock. */
222 static struct ocfs2_meta_cache_item *
223 ocfs2_search_cache_tree(struct ocfs2_caching_info *ci,
224                         sector_t block)
225 {
226         struct rb_node * n = ci->ci_cache.ci_tree.rb_node;
227         struct ocfs2_meta_cache_item *item = NULL;
228 
229         while (n) {
230                 item = rb_entry(n, struct ocfs2_meta_cache_item, c_node);
231 
232                 if (block < item->c_block)
233                         n = n->rb_left;
234                 else if (block > item->c_block)
235                         n = n->rb_right;
236                 else
237                         return item;
238         }
239 
240         return NULL;
241 }
242 
243 static int ocfs2_buffer_cached(struct ocfs2_caching_info *ci,
244                                struct buffer_head *bh)
245 {
246         int index = -1;
247         struct ocfs2_meta_cache_item *item = NULL;
248 
249         ocfs2_metadata_cache_lock(ci);
250 
251         trace_ocfs2_buffer_cached_begin(
252                 (unsigned long long)ocfs2_metadata_cache_owner(ci),
253                 (unsigned long long) bh->b_blocknr,
254                 !!(ci->ci_flags & OCFS2_CACHE_FL_INLINE));
255 
256         if (ci->ci_flags & OCFS2_CACHE_FL_INLINE)
257                 index = ocfs2_search_cache_array(ci, bh->b_blocknr);
258         else
259                 item = ocfs2_search_cache_tree(ci, bh->b_blocknr);
260 
261         ocfs2_metadata_cache_unlock(ci);
262 
263         trace_ocfs2_buffer_cached_end(index, item);
264 
265         return (index != -1) || (item != NULL);
266 }
267 
268 /* Warning: even if it returns true, this does *not* guarantee that
269  * the block is stored in our inode metadata cache.
270  *
271  * This can be called under lock_buffer()
272  */
273 int ocfs2_buffer_uptodate(struct ocfs2_caching_info *ci,
274                           struct buffer_head *bh)
275 {
276         /* Doesn't matter if the bh is in our cache or not -- if it's
277          * not marked uptodate then we know it can't have correct
278          * data. */
279         if (!buffer_uptodate(bh))
280                 return 0;
281 
282         /* OCFS2 does not allow multiple nodes to be changing the same
283          * block at the same time. */
284         if (buffer_jbd(bh))
285                 return 1;
286 
287         /* Ok, locally the buffer is marked as up to date, now search
288          * our cache to see if we can trust that. */
289         return ocfs2_buffer_cached(ci, bh);
290 }
291 
292 /*
293  * Determine whether a buffer is currently out on a read-ahead request.
294  * ci_io_sem should be held to serialize submitters with the logic here.
295  */
296 int ocfs2_buffer_read_ahead(struct ocfs2_caching_info *ci,
297                             struct buffer_head *bh)
298 {
299         return buffer_locked(bh) && ocfs2_buffer_cached(ci, bh);
300 }
301 
302 /* Requires ip_lock */
303 static void ocfs2_append_cache_array(struct ocfs2_caching_info *ci,
304                                      sector_t block)
305 {
306         BUG_ON(ci->ci_num_cached >= OCFS2_CACHE_INFO_MAX_ARRAY);
307 
308         trace_ocfs2_append_cache_array(
309                 (unsigned long long)ocfs2_metadata_cache_owner(ci),
310                 (unsigned long long)block, ci->ci_num_cached);
311 
312         ci->ci_cache.ci_array[ci->ci_num_cached] = block;
313         ci->ci_num_cached++;
314 }
315 
316 /* By now the caller should have checked that the item does *not*
317  * exist in the tree.
318  * Requires ip_lock. */
319 static void __ocfs2_insert_cache_tree(struct ocfs2_caching_info *ci,
320                                       struct ocfs2_meta_cache_item *new)
321 {
322         sector_t block = new->c_block;
323         struct rb_node *parent = NULL;
324         struct rb_node **p = &ci->ci_cache.ci_tree.rb_node;
325         struct ocfs2_meta_cache_item *tmp;
326 
327         trace_ocfs2_insert_cache_tree(
328                 (unsigned long long)ocfs2_metadata_cache_owner(ci),
329                 (unsigned long long)block, ci->ci_num_cached);
330 
331         while(*p) {
332                 parent = *p;
333 
334                 tmp = rb_entry(parent, struct ocfs2_meta_cache_item, c_node);
335 
336                 if (block < tmp->c_block)
337                         p = &(*p)->rb_left;
338                 else if (block > tmp->c_block)
339                         p = &(*p)->rb_right;
340                 else {
341                         /* This should never happen! */
342                         mlog(ML_ERROR, "Duplicate block %llu cached!\n",
343                              (unsigned long long) block);
344                         BUG();
345                 }
346         }
347 
348         rb_link_node(&new->c_node, parent, p);
349         rb_insert_color(&new->c_node, &ci->ci_cache.ci_tree);
350         ci->ci_num_cached++;
351 }
352 
353 /* co_cache_lock() must be held */
354 static inline int ocfs2_insert_can_use_array(struct ocfs2_caching_info *ci)
355 {
356         return (ci->ci_flags & OCFS2_CACHE_FL_INLINE) &&
357                 (ci->ci_num_cached < OCFS2_CACHE_INFO_MAX_ARRAY);
358 }
359 
360 /* tree should be exactly OCFS2_CACHE_INFO_MAX_ARRAY wide. NULL the
361  * pointers in tree after we use them - this allows caller to detect
362  * when to free in case of error.
363  *
364  * The co_cache_lock() must be held. */
365 static void ocfs2_expand_cache(struct ocfs2_caching_info *ci,
366                                struct ocfs2_meta_cache_item **tree)
367 {
368         int i;
369 
370         mlog_bug_on_msg(ci->ci_num_cached != OCFS2_CACHE_INFO_MAX_ARRAY,
371                         "Owner %llu, num cached = %u, should be %u\n",
372                         (unsigned long long)ocfs2_metadata_cache_owner(ci),
373                         ci->ci_num_cached, OCFS2_CACHE_INFO_MAX_ARRAY);
374         mlog_bug_on_msg(!(ci->ci_flags & OCFS2_CACHE_FL_INLINE),
375                         "Owner %llu not marked as inline anymore!\n",
376                         (unsigned long long)ocfs2_metadata_cache_owner(ci));
377 
378         /* Be careful to initialize the tree members *first* because
379          * once the ci_tree is used, the array is junk... */
380         for (i = 0; i < OCFS2_CACHE_INFO_MAX_ARRAY; i++)
381                 tree[i]->c_block = ci->ci_cache.ci_array[i];
382 
383         ci->ci_flags &= ~OCFS2_CACHE_FL_INLINE;
384         ci->ci_cache.ci_tree = RB_ROOT;
385         /* this will be set again by __ocfs2_insert_cache_tree */
386         ci->ci_num_cached = 0;
387 
388         for (i = 0; i < OCFS2_CACHE_INFO_MAX_ARRAY; i++) {
389                 __ocfs2_insert_cache_tree(ci, tree[i]);
390                 tree[i] = NULL;
391         }
392 
393         trace_ocfs2_expand_cache(
394                 (unsigned long long)ocfs2_metadata_cache_owner(ci),
395                 ci->ci_flags, ci->ci_num_cached);
396 }
397 
398 /* Slow path function - memory allocation is necessary. See the
399  * comment above ocfs2_set_buffer_uptodate for more information. */
400 static void __ocfs2_set_buffer_uptodate(struct ocfs2_caching_info *ci,
401                                         sector_t block,
402                                         int expand_tree)
403 {
404         int i;
405         struct ocfs2_meta_cache_item *new = NULL;
406         struct ocfs2_meta_cache_item *tree[OCFS2_CACHE_INFO_MAX_ARRAY] =
407                 { NULL, };
408 
409         trace_ocfs2_set_buffer_uptodate(
410                 (unsigned long long)ocfs2_metadata_cache_owner(ci),
411                 (unsigned long long)block, expand_tree);
412 
413         new = kmem_cache_alloc(ocfs2_uptodate_cachep, GFP_NOFS);
414         if (!new) {
415                 mlog_errno(-ENOMEM);
416                 return;
417         }
418         new->c_block = block;
419 
420         if (expand_tree) {
421                 /* Do *not* allocate an array here - the removal code
422                  * has no way of tracking that. */
423                 for (i = 0; i < OCFS2_CACHE_INFO_MAX_ARRAY; i++) {
424                         tree[i] = kmem_cache_alloc(ocfs2_uptodate_cachep,
425                                                    GFP_NOFS);
426                         if (!tree[i]) {
427                                 mlog_errno(-ENOMEM);
428                                 goto out_free;
429                         }
430 
431                         /* These are initialized in ocfs2_expand_cache! */
432                 }
433         }
434 
435         ocfs2_metadata_cache_lock(ci);
436         if (ocfs2_insert_can_use_array(ci)) {
437                 /* Ok, items were removed from the cache in between
438                  * locks. Detect this and revert back to the fast path */
439                 ocfs2_append_cache_array(ci, block);
440                 ocfs2_metadata_cache_unlock(ci);
441                 goto out_free;
442         }
443 
444         if (expand_tree)
445                 ocfs2_expand_cache(ci, tree);
446 
447         __ocfs2_insert_cache_tree(ci, new);
448         ocfs2_metadata_cache_unlock(ci);
449 
450         new = NULL;
451 out_free:
452         if (new)
453                 kmem_cache_free(ocfs2_uptodate_cachep, new);
454 
455         /* If these were used, then ocfs2_expand_cache re-set them to
456          * NULL for us. */
457         if (tree[0]) {
458                 for (i = 0; i < OCFS2_CACHE_INFO_MAX_ARRAY; i++)
459                         if (tree[i])
460                                 kmem_cache_free(ocfs2_uptodate_cachep,
461                                                 tree[i]);
462         }
463 }
464 
465 /* Item insertion is guarded by co_io_lock(), so the insertion path takes
466  * advantage of this by not rechecking for a duplicate insert during
467  * the slow case. Additionally, if the cache needs to be bumped up to
468  * a tree, the code will not recheck after acquiring the lock --
469  * multiple paths cannot be expanding to a tree at the same time.
470  *
471  * The slow path takes into account that items can be removed
472  * (including the whole tree wiped and reset) when this process it out
473  * allocating memory. In those cases, it reverts back to the fast
474  * path.
475  *
476  * Note that this function may actually fail to insert the block if
477  * memory cannot be allocated. This is not fatal however (but may
478  * result in a performance penalty)
479  *
480  * Readahead buffers can be passed in here before the I/O request is
481  * completed.
482  */
483 void ocfs2_set_buffer_uptodate(struct ocfs2_caching_info *ci,
484                                struct buffer_head *bh)
485 {
486         int expand;
487 
488         /* The block may very well exist in our cache already, so avoid
489          * doing any more work in that case. */
490         if (ocfs2_buffer_cached(ci, bh))
491                 return;
492 
493         trace_ocfs2_set_buffer_uptodate_begin(
494                 (unsigned long long)ocfs2_metadata_cache_owner(ci),
495                 (unsigned long long)bh->b_blocknr);
496 
497         /* No need to recheck under spinlock - insertion is guarded by
498          * co_io_lock() */
499         ocfs2_metadata_cache_lock(ci);
500         if (ocfs2_insert_can_use_array(ci)) {
501                 /* Fast case - it's an array and there's a free
502                  * spot. */
503                 ocfs2_append_cache_array(ci, bh->b_blocknr);
504                 ocfs2_metadata_cache_unlock(ci);
505                 return;
506         }
507 
508         expand = 0;
509         if (ci->ci_flags & OCFS2_CACHE_FL_INLINE) {
510                 /* We need to bump things up to a tree. */
511                 expand = 1;
512         }
513         ocfs2_metadata_cache_unlock(ci);
514 
515         __ocfs2_set_buffer_uptodate(ci, bh->b_blocknr, expand);
516 }
517 
518 /* Called against a newly allocated buffer. Most likely nobody should
519  * be able to read this sort of metadata while it's still being
520  * allocated, but this is careful to take co_io_lock() anyway. */
521 void ocfs2_set_new_buffer_uptodate(struct ocfs2_caching_info *ci,
522                                    struct buffer_head *bh)
523 {
524         /* This should definitely *not* exist in our cache */
525         BUG_ON(ocfs2_buffer_cached(ci, bh));
526 
527         set_buffer_uptodate(bh);
528 
529         ocfs2_metadata_cache_io_lock(ci);
530         ocfs2_set_buffer_uptodate(ci, bh);
531         ocfs2_metadata_cache_io_unlock(ci);
532 }
533 
534 /* Requires ip_lock. */
535 static void ocfs2_remove_metadata_array(struct ocfs2_caching_info *ci,
536                                         int index)
537 {
538         sector_t *array = ci->ci_cache.ci_array;
539         int bytes;
540 
541         BUG_ON(index < 0 || index >= OCFS2_CACHE_INFO_MAX_ARRAY);
542         BUG_ON(index >= ci->ci_num_cached);
543         BUG_ON(!ci->ci_num_cached);
544 
545         trace_ocfs2_remove_metadata_array(
546                 (unsigned long long)ocfs2_metadata_cache_owner(ci),
547                 index, ci->ci_num_cached);
548 
549         ci->ci_num_cached--;
550 
551         /* don't need to copy if the array is now empty, or if we
552          * removed at the tail */
553         if (ci->ci_num_cached && index < ci->ci_num_cached) {
554                 bytes = sizeof(sector_t) * (ci->ci_num_cached - index);
555                 memmove(&array[index], &array[index + 1], bytes);
556         }
557 }
558 
559 /* Requires ip_lock. */
560 static void ocfs2_remove_metadata_tree(struct ocfs2_caching_info *ci,
561                                        struct ocfs2_meta_cache_item *item)
562 {
563         trace_ocfs2_remove_metadata_tree(
564                 (unsigned long long)ocfs2_metadata_cache_owner(ci),
565                 (unsigned long long)item->c_block);
566 
567         rb_erase(&item->c_node, &ci->ci_cache.ci_tree);
568         ci->ci_num_cached--;
569 }
570 
571 static void ocfs2_remove_block_from_cache(struct ocfs2_caching_info *ci,
572                                           sector_t block)
573 {
574         int index;
575         struct ocfs2_meta_cache_item *item = NULL;
576 
577         ocfs2_metadata_cache_lock(ci);
578         trace_ocfs2_remove_block_from_cache(
579                 (unsigned long long)ocfs2_metadata_cache_owner(ci),
580                 (unsigned long long) block, ci->ci_num_cached,
581                 ci->ci_flags);
582 
583         if (ci->ci_flags & OCFS2_CACHE_FL_INLINE) {
584                 index = ocfs2_search_cache_array(ci, block);
585                 if (index != -1)
586                         ocfs2_remove_metadata_array(ci, index);
587         } else {
588                 item = ocfs2_search_cache_tree(ci, block);
589                 if (item)
590                         ocfs2_remove_metadata_tree(ci, item);
591         }
592         ocfs2_metadata_cache_unlock(ci);
593 
594         if (item)
595                 kmem_cache_free(ocfs2_uptodate_cachep, item);
596 }
597 
598 /*
599  * Called when we remove a chunk of metadata from an inode. We don't
600  * bother reverting things to an inlined array in the case of a remove
601  * which moves us back under the limit.
602  */
603 void ocfs2_remove_from_cache(struct ocfs2_caching_info *ci,
604                              struct buffer_head *bh)
605 {
606         sector_t block = bh->b_blocknr;
607 
608         ocfs2_remove_block_from_cache(ci, block);
609 }
610 
611 /* Called when we remove xattr clusters from an inode. */
612 void ocfs2_remove_xattr_clusters_from_cache(struct ocfs2_caching_info *ci,
613                                             sector_t block,
614                                             u32 c_len)
615 {
616         struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
617         unsigned int i, b_len = ocfs2_clusters_to_blocks(sb, 1) * c_len;
618 
619         for (i = 0; i < b_len; i++, block++)
620                 ocfs2_remove_block_from_cache(ci, block);
621 }
622 
623 int __init init_ocfs2_uptodate_cache(void)
624 {
625         ocfs2_uptodate_cachep = kmem_cache_create("ocfs2_uptodate",
626                                   sizeof(struct ocfs2_meta_cache_item),
627                                   0, SLAB_HWCACHE_ALIGN, NULL);
628         if (!ocfs2_uptodate_cachep)
629                 return -ENOMEM;
630 
631         return 0;
632 }
633 
634 void exit_ocfs2_uptodate_cache(void)
635 {
636         kmem_cache_destroy(ocfs2_uptodate_cachep);
637 }
638 

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