ring-buffer: Add event descriptor to simplify passing data
[linux-2.6-block.git] / fs / ext3 / xattr.c
1 /*
2  * linux/fs/ext3/xattr.c
3  *
4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
5  *
6  * Fix by Harrison Xing <harrison@mountainviewdata.com>.
7  * Ext3 code with a lot of help from Eric Jarman <ejarman@acm.org>.
8  * Extended attributes for symlinks and special files added per
9  *  suggestion of Luka Renko <luka.renko@hermes.si>.
10  * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
11  *  Red Hat Inc.
12  * ea-in-inode support by Alex Tomas <alex@clusterfs.com> aka bzzz
13  *  and Andreas Gruenbacher <agruen@suse.de>.
14  */
15
16 /*
17  * Extended attributes are stored directly in inodes (on file systems with
18  * inodes bigger than 128 bytes) and on additional disk blocks. The i_file_acl
19  * field contains the block number if an inode uses an additional block. All
20  * attributes must fit in the inode and one additional block. Blocks that
21  * contain the identical set of attributes may be shared among several inodes.
22  * Identical blocks are detected by keeping a cache of blocks that have
23  * recently been accessed.
24  *
25  * The attributes in inodes and on blocks have a different header; the entries
26  * are stored in the same format:
27  *
28  *   +------------------+
29  *   | header           |
30  *   | entry 1          | |
31  *   | entry 2          | | growing downwards
32  *   | entry 3          | v
33  *   | four null bytes  |
34  *   | . . .            |
35  *   | value 1          | ^
36  *   | value 3          | | growing upwards
37  *   | value 2          | |
38  *   +------------------+
39  *
40  * The header is followed by multiple entry descriptors. In disk blocks, the
41  * entry descriptors are kept sorted. In inodes, they are unsorted. The
42  * attribute values are aligned to the end of the block in no specific order.
43  *
44  * Locking strategy
45  * ----------------
46  * EXT3_I(inode)->i_file_acl is protected by EXT3_I(inode)->xattr_sem.
47  * EA blocks are only changed if they are exclusive to an inode, so
48  * holding xattr_sem also means that nothing but the EA block's reference
49  * count can change. Multiple writers to the same block are synchronized
50  * by the buffer lock.
51  */
52
53 #include "ext3.h"
54 #include <linux/mbcache.h>
55 #include <linux/quotaops.h>
56 #include "xattr.h"
57 #include "acl.h"
58
59 #define BHDR(bh) ((struct ext3_xattr_header *)((bh)->b_data))
60 #define ENTRY(ptr) ((struct ext3_xattr_entry *)(ptr))
61 #define BFIRST(bh) ENTRY(BHDR(bh)+1)
62 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
63
64 #define IHDR(inode, raw_inode) \
65         ((struct ext3_xattr_ibody_header *) \
66                 ((void *)raw_inode + \
67                  EXT3_GOOD_OLD_INODE_SIZE + \
68                  EXT3_I(inode)->i_extra_isize))
69 #define IFIRST(hdr) ((struct ext3_xattr_entry *)((hdr)+1))
70
71 #ifdef EXT3_XATTR_DEBUG
72 # define ea_idebug(inode, f...) do { \
73                 printk(KERN_DEBUG "inode %s:%lu: ", \
74                         inode->i_sb->s_id, inode->i_ino); \
75                 printk(f); \
76                 printk("\n"); \
77         } while (0)
78 # define ea_bdebug(bh, f...) do { \
79                 char b[BDEVNAME_SIZE]; \
80                 printk(KERN_DEBUG "block %s:%lu: ", \
81                         bdevname(bh->b_bdev, b), \
82                         (unsigned long) bh->b_blocknr); \
83                 printk(f); \
84                 printk("\n"); \
85         } while (0)
86 #else
87 # define ea_idebug(f...)
88 # define ea_bdebug(f...)
89 #endif
90
91 static void ext3_xattr_cache_insert(struct buffer_head *);
92 static struct buffer_head *ext3_xattr_cache_find(struct inode *,
93                                                  struct ext3_xattr_header *,
94                                                  struct mb_cache_entry **);
95 static void ext3_xattr_rehash(struct ext3_xattr_header *,
96                               struct ext3_xattr_entry *);
97 static int ext3_xattr_list(struct dentry *dentry, char *buffer,
98                            size_t buffer_size);
99
100 static struct mb_cache *ext3_xattr_cache;
101
102 static const struct xattr_handler *ext3_xattr_handler_map[] = {
103         [EXT3_XATTR_INDEX_USER]              = &ext3_xattr_user_handler,
104 #ifdef CONFIG_EXT3_FS_POSIX_ACL
105         [EXT3_XATTR_INDEX_POSIX_ACL_ACCESS]  = &posix_acl_access_xattr_handler,
106         [EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
107 #endif
108         [EXT3_XATTR_INDEX_TRUSTED]           = &ext3_xattr_trusted_handler,
109 #ifdef CONFIG_EXT3_FS_SECURITY
110         [EXT3_XATTR_INDEX_SECURITY]          = &ext3_xattr_security_handler,
111 #endif
112 };
113
114 const struct xattr_handler *ext3_xattr_handlers[] = {
115         &ext3_xattr_user_handler,
116         &ext3_xattr_trusted_handler,
117 #ifdef CONFIG_EXT3_FS_POSIX_ACL
118         &posix_acl_access_xattr_handler,
119         &posix_acl_default_xattr_handler,
120 #endif
121 #ifdef CONFIG_EXT3_FS_SECURITY
122         &ext3_xattr_security_handler,
123 #endif
124         NULL
125 };
126
127 static inline const struct xattr_handler *
128 ext3_xattr_handler(int name_index)
129 {
130         const struct xattr_handler *handler = NULL;
131
132         if (name_index > 0 && name_index < ARRAY_SIZE(ext3_xattr_handler_map))
133                 handler = ext3_xattr_handler_map[name_index];
134         return handler;
135 }
136
137 /*
138  * Inode operation listxattr()
139  *
140  * d_inode(dentry)->i_mutex: don't care
141  */
142 ssize_t
143 ext3_listxattr(struct dentry *dentry, char *buffer, size_t size)
144 {
145         return ext3_xattr_list(dentry, buffer, size);
146 }
147
148 static int
149 ext3_xattr_check_names(struct ext3_xattr_entry *entry, void *end)
150 {
151         while (!IS_LAST_ENTRY(entry)) {
152                 struct ext3_xattr_entry *next = EXT3_XATTR_NEXT(entry);
153                 if ((void *)next >= end)
154                         return -EIO;
155                 entry = next;
156         }
157         return 0;
158 }
159
160 static inline int
161 ext3_xattr_check_block(struct buffer_head *bh)
162 {
163         int error;
164
165         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
166             BHDR(bh)->h_blocks != cpu_to_le32(1))
167                 return -EIO;
168         error = ext3_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
169         return error;
170 }
171
172 static inline int
173 ext3_xattr_check_entry(struct ext3_xattr_entry *entry, size_t size)
174 {
175         size_t value_size = le32_to_cpu(entry->e_value_size);
176
177         if (entry->e_value_block != 0 || value_size > size ||
178             le16_to_cpu(entry->e_value_offs) + value_size > size)
179                 return -EIO;
180         return 0;
181 }
182
183 static int
184 ext3_xattr_find_entry(struct ext3_xattr_entry **pentry, int name_index,
185                       const char *name, size_t size, int sorted)
186 {
187         struct ext3_xattr_entry *entry;
188         size_t name_len;
189         int cmp = 1;
190
191         if (name == NULL)
192                 return -EINVAL;
193         name_len = strlen(name);
194         entry = *pentry;
195         for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
196                 cmp = name_index - entry->e_name_index;
197                 if (!cmp)
198                         cmp = name_len - entry->e_name_len;
199                 if (!cmp)
200                         cmp = memcmp(name, entry->e_name, name_len);
201                 if (cmp <= 0 && (sorted || cmp == 0))
202                         break;
203         }
204         *pentry = entry;
205         if (!cmp && ext3_xattr_check_entry(entry, size))
206                         return -EIO;
207         return cmp ? -ENODATA : 0;
208 }
209
210 static int
211 ext3_xattr_block_get(struct inode *inode, int name_index, const char *name,
212                      void *buffer, size_t buffer_size)
213 {
214         struct buffer_head *bh = NULL;
215         struct ext3_xattr_entry *entry;
216         size_t size;
217         int error;
218
219         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
220                   name_index, name, buffer, (long)buffer_size);
221
222         error = -ENODATA;
223         if (!EXT3_I(inode)->i_file_acl)
224                 goto cleanup;
225         ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
226         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
227         if (!bh)
228                 goto cleanup;
229         ea_bdebug(bh, "b_count=%d, refcount=%d",
230                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
231         if (ext3_xattr_check_block(bh)) {
232 bad_block:      ext3_error(inode->i_sb, __func__,
233                            "inode %lu: bad block "E3FSBLK, inode->i_ino,
234                            EXT3_I(inode)->i_file_acl);
235                 error = -EIO;
236                 goto cleanup;
237         }
238         ext3_xattr_cache_insert(bh);
239         entry = BFIRST(bh);
240         error = ext3_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
241         if (error == -EIO)
242                 goto bad_block;
243         if (error)
244                 goto cleanup;
245         size = le32_to_cpu(entry->e_value_size);
246         if (buffer) {
247                 error = -ERANGE;
248                 if (size > buffer_size)
249                         goto cleanup;
250                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
251                        size);
252         }
253         error = size;
254
255 cleanup:
256         brelse(bh);
257         return error;
258 }
259
260 static int
261 ext3_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
262                      void *buffer, size_t buffer_size)
263 {
264         struct ext3_xattr_ibody_header *header;
265         struct ext3_xattr_entry *entry;
266         struct ext3_inode *raw_inode;
267         struct ext3_iloc iloc;
268         size_t size;
269         void *end;
270         int error;
271
272         if (!ext3_test_inode_state(inode, EXT3_STATE_XATTR))
273                 return -ENODATA;
274         error = ext3_get_inode_loc(inode, &iloc);
275         if (error)
276                 return error;
277         raw_inode = ext3_raw_inode(&iloc);
278         header = IHDR(inode, raw_inode);
279         entry = IFIRST(header);
280         end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
281         error = ext3_xattr_check_names(entry, end);
282         if (error)
283                 goto cleanup;
284         error = ext3_xattr_find_entry(&entry, name_index, name,
285                                       end - (void *)entry, 0);
286         if (error)
287                 goto cleanup;
288         size = le32_to_cpu(entry->e_value_size);
289         if (buffer) {
290                 error = -ERANGE;
291                 if (size > buffer_size)
292                         goto cleanup;
293                 memcpy(buffer, (void *)IFIRST(header) +
294                        le16_to_cpu(entry->e_value_offs), size);
295         }
296         error = size;
297
298 cleanup:
299         brelse(iloc.bh);
300         return error;
301 }
302
303 /*
304  * ext3_xattr_get()
305  *
306  * Copy an extended attribute into the buffer
307  * provided, or compute the buffer size required.
308  * Buffer is NULL to compute the size of the buffer required.
309  *
310  * Returns a negative error number on failure, or the number of bytes
311  * used / required on success.
312  */
313 int
314 ext3_xattr_get(struct inode *inode, int name_index, const char *name,
315                void *buffer, size_t buffer_size)
316 {
317         int error;
318
319         down_read(&EXT3_I(inode)->xattr_sem);
320         error = ext3_xattr_ibody_get(inode, name_index, name, buffer,
321                                      buffer_size);
322         if (error == -ENODATA)
323                 error = ext3_xattr_block_get(inode, name_index, name, buffer,
324                                              buffer_size);
325         up_read(&EXT3_I(inode)->xattr_sem);
326         return error;
327 }
328
329 static int
330 ext3_xattr_list_entries(struct dentry *dentry, struct ext3_xattr_entry *entry,
331                         char *buffer, size_t buffer_size)
332 {
333         size_t rest = buffer_size;
334
335         for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
336                 const struct xattr_handler *handler =
337                         ext3_xattr_handler(entry->e_name_index);
338
339                 if (handler) {
340                         size_t size = handler->list(dentry, buffer, rest,
341                                                     entry->e_name,
342                                                     entry->e_name_len,
343                                                     handler->flags);
344                         if (buffer) {
345                                 if (size > rest)
346                                         return -ERANGE;
347                                 buffer += size;
348                         }
349                         rest -= size;
350                 }
351         }
352         return buffer_size - rest;
353 }
354
355 static int
356 ext3_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
357 {
358         struct inode *inode = d_inode(dentry);
359         struct buffer_head *bh = NULL;
360         int error;
361
362         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
363                   buffer, (long)buffer_size);
364
365         error = 0;
366         if (!EXT3_I(inode)->i_file_acl)
367                 goto cleanup;
368         ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
369         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
370         error = -EIO;
371         if (!bh)
372                 goto cleanup;
373         ea_bdebug(bh, "b_count=%d, refcount=%d",
374                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
375         if (ext3_xattr_check_block(bh)) {
376                 ext3_error(inode->i_sb, __func__,
377                            "inode %lu: bad block "E3FSBLK, inode->i_ino,
378                            EXT3_I(inode)->i_file_acl);
379                 error = -EIO;
380                 goto cleanup;
381         }
382         ext3_xattr_cache_insert(bh);
383         error = ext3_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
384
385 cleanup:
386         brelse(bh);
387
388         return error;
389 }
390
391 static int
392 ext3_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
393 {
394         struct inode *inode = d_inode(dentry);
395         struct ext3_xattr_ibody_header *header;
396         struct ext3_inode *raw_inode;
397         struct ext3_iloc iloc;
398         void *end;
399         int error;
400
401         if (!ext3_test_inode_state(inode, EXT3_STATE_XATTR))
402                 return 0;
403         error = ext3_get_inode_loc(inode, &iloc);
404         if (error)
405                 return error;
406         raw_inode = ext3_raw_inode(&iloc);
407         header = IHDR(inode, raw_inode);
408         end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
409         error = ext3_xattr_check_names(IFIRST(header), end);
410         if (error)
411                 goto cleanup;
412         error = ext3_xattr_list_entries(dentry, IFIRST(header),
413                                         buffer, buffer_size);
414
415 cleanup:
416         brelse(iloc.bh);
417         return error;
418 }
419
420 /*
421  * ext3_xattr_list()
422  *
423  * Copy a list of attribute names into the buffer
424  * provided, or compute the buffer size required.
425  * Buffer is NULL to compute the size of the buffer required.
426  *
427  * Returns a negative error number on failure, or the number of bytes
428  * used / required on success.
429  */
430 static int
431 ext3_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
432 {
433         int i_error, b_error;
434
435         down_read(&EXT3_I(d_inode(dentry))->xattr_sem);
436         i_error = ext3_xattr_ibody_list(dentry, buffer, buffer_size);
437         if (i_error < 0) {
438                 b_error = 0;
439         } else {
440                 if (buffer) {
441                         buffer += i_error;
442                         buffer_size -= i_error;
443                 }
444                 b_error = ext3_xattr_block_list(dentry, buffer, buffer_size);
445                 if (b_error < 0)
446                         i_error = 0;
447         }
448         up_read(&EXT3_I(d_inode(dentry))->xattr_sem);
449         return i_error + b_error;
450 }
451
452 /*
453  * If the EXT3_FEATURE_COMPAT_EXT_ATTR feature of this file system is
454  * not set, set it.
455  */
456 static void ext3_xattr_update_super_block(handle_t *handle,
457                                           struct super_block *sb)
458 {
459         if (EXT3_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR))
460                 return;
461
462         if (ext3_journal_get_write_access(handle, EXT3_SB(sb)->s_sbh) == 0) {
463                 EXT3_SET_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR);
464                 ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
465         }
466 }
467
468 /*
469  * Release the xattr block BH: If the reference count is > 1, decrement
470  * it; otherwise free the block.
471  */
472 static void
473 ext3_xattr_release_block(handle_t *handle, struct inode *inode,
474                          struct buffer_head *bh)
475 {
476         struct mb_cache_entry *ce = NULL;
477         int error = 0;
478
479         ce = mb_cache_entry_get(ext3_xattr_cache, bh->b_bdev, bh->b_blocknr);
480         error = ext3_journal_get_write_access(handle, bh);
481         if (error)
482                  goto out;
483
484         lock_buffer(bh);
485
486         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
487                 ea_bdebug(bh, "refcount now=0; freeing");
488                 if (ce)
489                         mb_cache_entry_free(ce);
490                 ext3_free_blocks(handle, inode, bh->b_blocknr, 1);
491                 get_bh(bh);
492                 ext3_forget(handle, 1, inode, bh, bh->b_blocknr);
493         } else {
494                 le32_add_cpu(&BHDR(bh)->h_refcount, -1);
495                 error = ext3_journal_dirty_metadata(handle, bh);
496                 if (IS_SYNC(inode))
497                         handle->h_sync = 1;
498                 dquot_free_block(inode, 1);
499                 ea_bdebug(bh, "refcount now=%d; releasing",
500                           le32_to_cpu(BHDR(bh)->h_refcount));
501                 if (ce)
502                         mb_cache_entry_release(ce);
503         }
504         unlock_buffer(bh);
505 out:
506         ext3_std_error(inode->i_sb, error);
507         return;
508 }
509
510 struct ext3_xattr_info {
511         int name_index;
512         const char *name;
513         const void *value;
514         size_t value_len;
515 };
516
517 struct ext3_xattr_search {
518         struct ext3_xattr_entry *first;
519         void *base;
520         void *end;
521         struct ext3_xattr_entry *here;
522         int not_found;
523 };
524
525 static int
526 ext3_xattr_set_entry(struct ext3_xattr_info *i, struct ext3_xattr_search *s)
527 {
528         struct ext3_xattr_entry *last;
529         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
530
531         /* Compute min_offs and last. */
532         last = s->first;
533         for (; !IS_LAST_ENTRY(last); last = EXT3_XATTR_NEXT(last)) {
534                 if (!last->e_value_block && last->e_value_size) {
535                         size_t offs = le16_to_cpu(last->e_value_offs);
536                         if (offs < min_offs)
537                                 min_offs = offs;
538                 }
539         }
540         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
541         if (!s->not_found) {
542                 if (!s->here->e_value_block && s->here->e_value_size) {
543                         size_t size = le32_to_cpu(s->here->e_value_size);
544                         free += EXT3_XATTR_SIZE(size);
545                 }
546                 free += EXT3_XATTR_LEN(name_len);
547         }
548         if (i->value) {
549                 if (free < EXT3_XATTR_LEN(name_len) +
550                            EXT3_XATTR_SIZE(i->value_len))
551                         return -ENOSPC;
552         }
553
554         if (i->value && s->not_found) {
555                 /* Insert the new name. */
556                 size_t size = EXT3_XATTR_LEN(name_len);
557                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
558                 memmove((void *)s->here + size, s->here, rest);
559                 memset(s->here, 0, size);
560                 s->here->e_name_index = i->name_index;
561                 s->here->e_name_len = name_len;
562                 memcpy(s->here->e_name, i->name, name_len);
563         } else {
564                 if (!s->here->e_value_block && s->here->e_value_size) {
565                         void *first_val = s->base + min_offs;
566                         size_t offs = le16_to_cpu(s->here->e_value_offs);
567                         void *val = s->base + offs;
568                         size_t size = EXT3_XATTR_SIZE(
569                                 le32_to_cpu(s->here->e_value_size));
570
571                         if (i->value && size == EXT3_XATTR_SIZE(i->value_len)) {
572                                 /* The old and the new value have the same
573                                    size. Just replace. */
574                                 s->here->e_value_size =
575                                         cpu_to_le32(i->value_len);
576                                 memset(val + size - EXT3_XATTR_PAD, 0,
577                                        EXT3_XATTR_PAD); /* Clear pad bytes. */
578                                 memcpy(val, i->value, i->value_len);
579                                 return 0;
580                         }
581
582                         /* Remove the old value. */
583                         memmove(first_val + size, first_val, val - first_val);
584                         memset(first_val, 0, size);
585                         s->here->e_value_size = 0;
586                         s->here->e_value_offs = 0;
587                         min_offs += size;
588
589                         /* Adjust all value offsets. */
590                         last = s->first;
591                         while (!IS_LAST_ENTRY(last)) {
592                                 size_t o = le16_to_cpu(last->e_value_offs);
593                                 if (!last->e_value_block &&
594                                     last->e_value_size && o < offs)
595                                         last->e_value_offs =
596                                                 cpu_to_le16(o + size);
597                                 last = EXT3_XATTR_NEXT(last);
598                         }
599                 }
600                 if (!i->value) {
601                         /* Remove the old name. */
602                         size_t size = EXT3_XATTR_LEN(name_len);
603                         last = ENTRY((void *)last - size);
604                         memmove(s->here, (void *)s->here + size,
605                                 (void *)last - (void *)s->here + sizeof(__u32));
606                         memset(last, 0, size);
607                 }
608         }
609
610         if (i->value) {
611                 /* Insert the new value. */
612                 s->here->e_value_size = cpu_to_le32(i->value_len);
613                 if (i->value_len) {
614                         size_t size = EXT3_XATTR_SIZE(i->value_len);
615                         void *val = s->base + min_offs - size;
616                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
617                         memset(val + size - EXT3_XATTR_PAD, 0,
618                                EXT3_XATTR_PAD); /* Clear the pad bytes. */
619                         memcpy(val, i->value, i->value_len);
620                 }
621         }
622         return 0;
623 }
624
625 struct ext3_xattr_block_find {
626         struct ext3_xattr_search s;
627         struct buffer_head *bh;
628 };
629
630 static int
631 ext3_xattr_block_find(struct inode *inode, struct ext3_xattr_info *i,
632                       struct ext3_xattr_block_find *bs)
633 {
634         struct super_block *sb = inode->i_sb;
635         int error;
636
637         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
638                   i->name_index, i->name, i->value, (long)i->value_len);
639
640         if (EXT3_I(inode)->i_file_acl) {
641                 /* The inode already has an extended attribute block. */
642                 bs->bh = sb_bread(sb, EXT3_I(inode)->i_file_acl);
643                 error = -EIO;
644                 if (!bs->bh)
645                         goto cleanup;
646                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
647                         atomic_read(&(bs->bh->b_count)),
648                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
649                 if (ext3_xattr_check_block(bs->bh)) {
650                         ext3_error(sb, __func__,
651                                 "inode %lu: bad block "E3FSBLK, inode->i_ino,
652                                 EXT3_I(inode)->i_file_acl);
653                         error = -EIO;
654                         goto cleanup;
655                 }
656                 /* Find the named attribute. */
657                 bs->s.base = BHDR(bs->bh);
658                 bs->s.first = BFIRST(bs->bh);
659                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
660                 bs->s.here = bs->s.first;
661                 error = ext3_xattr_find_entry(&bs->s.here, i->name_index,
662                                               i->name, bs->bh->b_size, 1);
663                 if (error && error != -ENODATA)
664                         goto cleanup;
665                 bs->s.not_found = error;
666         }
667         error = 0;
668
669 cleanup:
670         return error;
671 }
672
673 static int
674 ext3_xattr_block_set(handle_t *handle, struct inode *inode,
675                      struct ext3_xattr_info *i,
676                      struct ext3_xattr_block_find *bs)
677 {
678         struct super_block *sb = inode->i_sb;
679         struct buffer_head *new_bh = NULL;
680         struct ext3_xattr_search *s = &bs->s;
681         struct mb_cache_entry *ce = NULL;
682         int error = 0;
683
684 #define header(x) ((struct ext3_xattr_header *)(x))
685
686         if (i->value && i->value_len > sb->s_blocksize)
687                 return -ENOSPC;
688         if (s->base) {
689                 ce = mb_cache_entry_get(ext3_xattr_cache, bs->bh->b_bdev,
690                                         bs->bh->b_blocknr);
691                 error = ext3_journal_get_write_access(handle, bs->bh);
692                 if (error)
693                         goto cleanup;
694                 lock_buffer(bs->bh);
695
696                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
697                         if (ce) {
698                                 mb_cache_entry_free(ce);
699                                 ce = NULL;
700                         }
701                         ea_bdebug(bs->bh, "modifying in-place");
702                         error = ext3_xattr_set_entry(i, s);
703                         if (!error) {
704                                 if (!IS_LAST_ENTRY(s->first))
705                                         ext3_xattr_rehash(header(s->base),
706                                                           s->here);
707                                 ext3_xattr_cache_insert(bs->bh);
708                         }
709                         unlock_buffer(bs->bh);
710                         if (error == -EIO)
711                                 goto bad_block;
712                         if (!error)
713                                 error = ext3_journal_dirty_metadata(handle,
714                                                                     bs->bh);
715                         if (error)
716                                 goto cleanup;
717                         goto inserted;
718                 } else {
719                         int offset = (char *)s->here - bs->bh->b_data;
720
721                         unlock_buffer(bs->bh);
722                         journal_release_buffer(handle, bs->bh);
723
724                         if (ce) {
725                                 mb_cache_entry_release(ce);
726                                 ce = NULL;
727                         }
728                         ea_bdebug(bs->bh, "cloning");
729                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
730                         error = -ENOMEM;
731                         if (s->base == NULL)
732                                 goto cleanup;
733                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
734                         s->first = ENTRY(header(s->base)+1);
735                         header(s->base)->h_refcount = cpu_to_le32(1);
736                         s->here = ENTRY(s->base + offset);
737                         s->end = s->base + bs->bh->b_size;
738                 }
739         } else {
740                 /* Allocate a buffer where we construct the new block. */
741                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
742                 /* assert(header == s->base) */
743                 error = -ENOMEM;
744                 if (s->base == NULL)
745                         goto cleanup;
746                 header(s->base)->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
747                 header(s->base)->h_blocks = cpu_to_le32(1);
748                 header(s->base)->h_refcount = cpu_to_le32(1);
749                 s->first = ENTRY(header(s->base)+1);
750                 s->here = ENTRY(header(s->base)+1);
751                 s->end = s->base + sb->s_blocksize;
752         }
753
754         error = ext3_xattr_set_entry(i, s);
755         if (error == -EIO)
756                 goto bad_block;
757         if (error)
758                 goto cleanup;
759         if (!IS_LAST_ENTRY(s->first))
760                 ext3_xattr_rehash(header(s->base), s->here);
761
762 inserted:
763         if (!IS_LAST_ENTRY(s->first)) {
764                 new_bh = ext3_xattr_cache_find(inode, header(s->base), &ce);
765                 if (new_bh) {
766                         /* We found an identical block in the cache. */
767                         if (new_bh == bs->bh)
768                                 ea_bdebug(new_bh, "keeping");
769                         else {
770                                 /* The old block is released after updating
771                                    the inode. */
772                                 error = dquot_alloc_block(inode, 1);
773                                 if (error)
774                                         goto cleanup;
775                                 error = ext3_journal_get_write_access(handle,
776                                                                       new_bh);
777                                 if (error)
778                                         goto cleanup_dquot;
779                                 lock_buffer(new_bh);
780                                 le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
781                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
782                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
783                                 unlock_buffer(new_bh);
784                                 error = ext3_journal_dirty_metadata(handle,
785                                                                     new_bh);
786                                 if (error)
787                                         goto cleanup_dquot;
788                         }
789                         mb_cache_entry_release(ce);
790                         ce = NULL;
791                 } else if (bs->bh && s->base == bs->bh->b_data) {
792                         /* We were modifying this block in-place. */
793                         ea_bdebug(bs->bh, "keeping this block");
794                         new_bh = bs->bh;
795                         get_bh(new_bh);
796                 } else {
797                         /* We need to allocate a new block */
798                         ext3_fsblk_t goal = ext3_group_first_block_no(sb,
799                                                 EXT3_I(inode)->i_block_group);
800                         ext3_fsblk_t block;
801
802                         /*
803                          * Protect us agaist concurrent allocations to the
804                          * same inode from ext3_..._writepage(). Reservation
805                          * code does not expect racing allocations.
806                          */
807                         mutex_lock(&EXT3_I(inode)->truncate_mutex);
808                         block = ext3_new_block(handle, inode, goal, &error);
809                         mutex_unlock(&EXT3_I(inode)->truncate_mutex);
810                         if (error)
811                                 goto cleanup;
812                         ea_idebug(inode, "creating block %d", block);
813
814                         new_bh = sb_getblk(sb, block);
815                         if (unlikely(!new_bh)) {
816 getblk_failed:
817                                 ext3_free_blocks(handle, inode, block, 1);
818                                 error = -ENOMEM;
819                                 goto cleanup;
820                         }
821                         lock_buffer(new_bh);
822                         error = ext3_journal_get_create_access(handle, new_bh);
823                         if (error) {
824                                 unlock_buffer(new_bh);
825                                 goto getblk_failed;
826                         }
827                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
828                         set_buffer_uptodate(new_bh);
829                         unlock_buffer(new_bh);
830                         ext3_xattr_cache_insert(new_bh);
831                         error = ext3_journal_dirty_metadata(handle, new_bh);
832                         if (error)
833                                 goto cleanup;
834                 }
835         }
836
837         /* Update the inode. */
838         EXT3_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
839
840         /* Drop the previous xattr block. */
841         if (bs->bh && bs->bh != new_bh)
842                 ext3_xattr_release_block(handle, inode, bs->bh);
843         error = 0;
844
845 cleanup:
846         if (ce)
847                 mb_cache_entry_release(ce);
848         brelse(new_bh);
849         if (!(bs->bh && s->base == bs->bh->b_data))
850                 kfree(s->base);
851
852         return error;
853
854 cleanup_dquot:
855         dquot_free_block(inode, 1);
856         goto cleanup;
857
858 bad_block:
859         ext3_error(inode->i_sb, __func__,
860                    "inode %lu: bad block "E3FSBLK, inode->i_ino,
861                    EXT3_I(inode)->i_file_acl);
862         goto cleanup;
863
864 #undef header
865 }
866
867 struct ext3_xattr_ibody_find {
868         struct ext3_xattr_search s;
869         struct ext3_iloc iloc;
870 };
871
872 static int
873 ext3_xattr_ibody_find(struct inode *inode, struct ext3_xattr_info *i,
874                       struct ext3_xattr_ibody_find *is)
875 {
876         struct ext3_xattr_ibody_header *header;
877         struct ext3_inode *raw_inode;
878         int error;
879
880         if (EXT3_I(inode)->i_extra_isize == 0)
881                 return 0;
882         raw_inode = ext3_raw_inode(&is->iloc);
883         header = IHDR(inode, raw_inode);
884         is->s.base = is->s.first = IFIRST(header);
885         is->s.here = is->s.first;
886         is->s.end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
887         if (ext3_test_inode_state(inode, EXT3_STATE_XATTR)) {
888                 error = ext3_xattr_check_names(IFIRST(header), is->s.end);
889                 if (error)
890                         return error;
891                 /* Find the named attribute. */
892                 error = ext3_xattr_find_entry(&is->s.here, i->name_index,
893                                               i->name, is->s.end -
894                                               (void *)is->s.base, 0);
895                 if (error && error != -ENODATA)
896                         return error;
897                 is->s.not_found = error;
898         }
899         return 0;
900 }
901
902 static int
903 ext3_xattr_ibody_set(handle_t *handle, struct inode *inode,
904                      struct ext3_xattr_info *i,
905                      struct ext3_xattr_ibody_find *is)
906 {
907         struct ext3_xattr_ibody_header *header;
908         struct ext3_xattr_search *s = &is->s;
909         int error;
910
911         if (EXT3_I(inode)->i_extra_isize == 0)
912                 return -ENOSPC;
913         error = ext3_xattr_set_entry(i, s);
914         if (error)
915                 return error;
916         header = IHDR(inode, ext3_raw_inode(&is->iloc));
917         if (!IS_LAST_ENTRY(s->first)) {
918                 header->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
919                 ext3_set_inode_state(inode, EXT3_STATE_XATTR);
920         } else {
921                 header->h_magic = cpu_to_le32(0);
922                 ext3_clear_inode_state(inode, EXT3_STATE_XATTR);
923         }
924         return 0;
925 }
926
927 /*
928  * ext3_xattr_set_handle()
929  *
930  * Create, replace or remove an extended attribute for this inode.  Value
931  * is NULL to remove an existing extended attribute, and non-NULL to
932  * either replace an existing extended attribute, or create a new extended
933  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
934  * specify that an extended attribute must exist and must not exist
935  * previous to the call, respectively.
936  *
937  * Returns 0, or a negative error number on failure.
938  */
939 int
940 ext3_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
941                       const char *name, const void *value, size_t value_len,
942                       int flags)
943 {
944         struct ext3_xattr_info i = {
945                 .name_index = name_index,
946                 .name = name,
947                 .value = value,
948                 .value_len = value_len,
949
950         };
951         struct ext3_xattr_ibody_find is = {
952                 .s = { .not_found = -ENODATA, },
953         };
954         struct ext3_xattr_block_find bs = {
955                 .s = { .not_found = -ENODATA, },
956         };
957         int error;
958
959         if (!name)
960                 return -EINVAL;
961         if (strlen(name) > 255)
962                 return -ERANGE;
963         down_write(&EXT3_I(inode)->xattr_sem);
964         error = ext3_get_inode_loc(inode, &is.iloc);
965         if (error)
966                 goto cleanup;
967
968         error = ext3_journal_get_write_access(handle, is.iloc.bh);
969         if (error)
970                 goto cleanup;
971
972         if (ext3_test_inode_state(inode, EXT3_STATE_NEW)) {
973                 struct ext3_inode *raw_inode = ext3_raw_inode(&is.iloc);
974                 memset(raw_inode, 0, EXT3_SB(inode->i_sb)->s_inode_size);
975                 ext3_clear_inode_state(inode, EXT3_STATE_NEW);
976         }
977
978         error = ext3_xattr_ibody_find(inode, &i, &is);
979         if (error)
980                 goto cleanup;
981         if (is.s.not_found)
982                 error = ext3_xattr_block_find(inode, &i, &bs);
983         if (error)
984                 goto cleanup;
985         if (is.s.not_found && bs.s.not_found) {
986                 error = -ENODATA;
987                 if (flags & XATTR_REPLACE)
988                         goto cleanup;
989                 error = 0;
990                 if (!value)
991                         goto cleanup;
992         } else {
993                 error = -EEXIST;
994                 if (flags & XATTR_CREATE)
995                         goto cleanup;
996         }
997         if (!value) {
998                 if (!is.s.not_found)
999                         error = ext3_xattr_ibody_set(handle, inode, &i, &is);
1000                 else if (!bs.s.not_found)
1001                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1002         } else {
1003                 error = ext3_xattr_ibody_set(handle, inode, &i, &is);
1004                 if (!error && !bs.s.not_found) {
1005                         i.value = NULL;
1006                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1007                 } else if (error == -ENOSPC) {
1008                         if (EXT3_I(inode)->i_file_acl && !bs.s.base) {
1009                                 error = ext3_xattr_block_find(inode, &i, &bs);
1010                                 if (error)
1011                                         goto cleanup;
1012                         }
1013                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1014                         if (error)
1015                                 goto cleanup;
1016                         if (!is.s.not_found) {
1017                                 i.value = NULL;
1018                                 error = ext3_xattr_ibody_set(handle, inode, &i,
1019                                                              &is);
1020                         }
1021                 }
1022         }
1023         if (!error) {
1024                 ext3_xattr_update_super_block(handle, inode->i_sb);
1025                 inode->i_ctime = CURRENT_TIME_SEC;
1026                 error = ext3_mark_iloc_dirty(handle, inode, &is.iloc);
1027                 /*
1028                  * The bh is consumed by ext3_mark_iloc_dirty, even with
1029                  * error != 0.
1030                  */
1031                 is.iloc.bh = NULL;
1032                 if (IS_SYNC(inode))
1033                         handle->h_sync = 1;
1034         }
1035
1036 cleanup:
1037         brelse(is.iloc.bh);
1038         brelse(bs.bh);
1039         up_write(&EXT3_I(inode)->xattr_sem);
1040         return error;
1041 }
1042
1043 /*
1044  * ext3_xattr_set()
1045  *
1046  * Like ext3_xattr_set_handle, but start from an inode. This extended
1047  * attribute modification is a filesystem transaction by itself.
1048  *
1049  * Returns 0, or a negative error number on failure.
1050  */
1051 int
1052 ext3_xattr_set(struct inode *inode, int name_index, const char *name,
1053                const void *value, size_t value_len, int flags)
1054 {
1055         handle_t *handle;
1056         int error, retries = 0;
1057
1058 retry:
1059         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
1060         if (IS_ERR(handle)) {
1061                 error = PTR_ERR(handle);
1062         } else {
1063                 int error2;
1064
1065                 error = ext3_xattr_set_handle(handle, inode, name_index, name,
1066                                               value, value_len, flags);
1067                 error2 = ext3_journal_stop(handle);
1068                 if (error == -ENOSPC &&
1069                     ext3_should_retry_alloc(inode->i_sb, &retries))
1070                         goto retry;
1071                 if (error == 0)
1072                         error = error2;
1073         }
1074
1075         return error;
1076 }
1077
1078 /*
1079  * ext3_xattr_delete_inode()
1080  *
1081  * Free extended attribute resources associated with this inode. This
1082  * is called immediately before an inode is freed. We have exclusive
1083  * access to the inode.
1084  */
1085 void
1086 ext3_xattr_delete_inode(handle_t *handle, struct inode *inode)
1087 {
1088         struct buffer_head *bh = NULL;
1089
1090         if (!EXT3_I(inode)->i_file_acl)
1091                 goto cleanup;
1092         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
1093         if (!bh) {
1094                 ext3_error(inode->i_sb, __func__,
1095                         "inode %lu: block "E3FSBLK" read error", inode->i_ino,
1096                         EXT3_I(inode)->i_file_acl);
1097                 goto cleanup;
1098         }
1099         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
1100             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1101                 ext3_error(inode->i_sb, __func__,
1102                         "inode %lu: bad block "E3FSBLK, inode->i_ino,
1103                         EXT3_I(inode)->i_file_acl);
1104                 goto cleanup;
1105         }
1106         ext3_xattr_release_block(handle, inode, bh);
1107         EXT3_I(inode)->i_file_acl = 0;
1108
1109 cleanup:
1110         brelse(bh);
1111 }
1112
1113 /*
1114  * ext3_xattr_put_super()
1115  *
1116  * This is called when a file system is unmounted.
1117  */
1118 void
1119 ext3_xattr_put_super(struct super_block *sb)
1120 {
1121         mb_cache_shrink(sb->s_bdev);
1122 }
1123
1124 /*
1125  * ext3_xattr_cache_insert()
1126  *
1127  * Create a new entry in the extended attribute cache, and insert
1128  * it unless such an entry is already in the cache.
1129  *
1130  * Returns 0, or a negative error number on failure.
1131  */
1132 static void
1133 ext3_xattr_cache_insert(struct buffer_head *bh)
1134 {
1135         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1136         struct mb_cache_entry *ce;
1137         int error;
1138
1139         ce = mb_cache_entry_alloc(ext3_xattr_cache, GFP_NOFS);
1140         if (!ce) {
1141                 ea_bdebug(bh, "out of memory");
1142                 return;
1143         }
1144         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
1145         if (error) {
1146                 mb_cache_entry_free(ce);
1147                 if (error == -EBUSY) {
1148                         ea_bdebug(bh, "already in cache");
1149                         error = 0;
1150                 }
1151         } else {
1152                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1153                 mb_cache_entry_release(ce);
1154         }
1155 }
1156
1157 /*
1158  * ext3_xattr_cmp()
1159  *
1160  * Compare two extended attribute blocks for equality.
1161  *
1162  * Returns 0 if the blocks are equal, 1 if they differ, and
1163  * a negative error number on errors.
1164  */
1165 static int
1166 ext3_xattr_cmp(struct ext3_xattr_header *header1,
1167                struct ext3_xattr_header *header2)
1168 {
1169         struct ext3_xattr_entry *entry1, *entry2;
1170
1171         entry1 = ENTRY(header1+1);
1172         entry2 = ENTRY(header2+1);
1173         while (!IS_LAST_ENTRY(entry1)) {
1174                 if (IS_LAST_ENTRY(entry2))
1175                         return 1;
1176                 if (entry1->e_hash != entry2->e_hash ||
1177                     entry1->e_name_index != entry2->e_name_index ||
1178                     entry1->e_name_len != entry2->e_name_len ||
1179                     entry1->e_value_size != entry2->e_value_size ||
1180                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1181                         return 1;
1182                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1183                         return -EIO;
1184                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1185                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1186                            le32_to_cpu(entry1->e_value_size)))
1187                         return 1;
1188
1189                 entry1 = EXT3_XATTR_NEXT(entry1);
1190                 entry2 = EXT3_XATTR_NEXT(entry2);
1191         }
1192         if (!IS_LAST_ENTRY(entry2))
1193                 return 1;
1194         return 0;
1195 }
1196
1197 /*
1198  * ext3_xattr_cache_find()
1199  *
1200  * Find an identical extended attribute block.
1201  *
1202  * Returns a pointer to the block found, or NULL if such a block was
1203  * not found or an error occurred.
1204  */
1205 static struct buffer_head *
1206 ext3_xattr_cache_find(struct inode *inode, struct ext3_xattr_header *header,
1207                       struct mb_cache_entry **pce)
1208 {
1209         __u32 hash = le32_to_cpu(header->h_hash);
1210         struct mb_cache_entry *ce;
1211
1212         if (!header->h_hash)
1213                 return NULL;  /* never share */
1214         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1215 again:
1216         ce = mb_cache_entry_find_first(ext3_xattr_cache, inode->i_sb->s_bdev,
1217                                        hash);
1218         while (ce) {
1219                 struct buffer_head *bh;
1220
1221                 if (IS_ERR(ce)) {
1222                         if (PTR_ERR(ce) == -EAGAIN)
1223                                 goto again;
1224                         break;
1225                 }
1226                 bh = sb_bread(inode->i_sb, ce->e_block);
1227                 if (!bh) {
1228                         ext3_error(inode->i_sb, __func__,
1229                                 "inode %lu: block %lu read error",
1230                                 inode->i_ino, (unsigned long) ce->e_block);
1231                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1232                                 EXT3_XATTR_REFCOUNT_MAX) {
1233                         ea_idebug(inode, "block %lu refcount %d>=%d",
1234                                   (unsigned long) ce->e_block,
1235                                   le32_to_cpu(BHDR(bh)->h_refcount),
1236                                           EXT3_XATTR_REFCOUNT_MAX);
1237                 } else if (ext3_xattr_cmp(header, BHDR(bh)) == 0) {
1238                         *pce = ce;
1239                         return bh;
1240                 }
1241                 brelse(bh);
1242                 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
1243         }
1244         return NULL;
1245 }
1246
1247 #define NAME_HASH_SHIFT 5
1248 #define VALUE_HASH_SHIFT 16
1249
1250 /*
1251  * ext3_xattr_hash_entry()
1252  *
1253  * Compute the hash of an extended attribute.
1254  */
1255 static inline void ext3_xattr_hash_entry(struct ext3_xattr_header *header,
1256                                          struct ext3_xattr_entry *entry)
1257 {
1258         __u32 hash = 0;
1259         char *name = entry->e_name;
1260         int n;
1261
1262         for (n=0; n < entry->e_name_len; n++) {
1263                 hash = (hash << NAME_HASH_SHIFT) ^
1264                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1265                        *name++;
1266         }
1267
1268         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1269                 __le32 *value = (__le32 *)((char *)header +
1270                         le16_to_cpu(entry->e_value_offs));
1271                 for (n = (le32_to_cpu(entry->e_value_size) +
1272                      EXT3_XATTR_ROUND) >> EXT3_XATTR_PAD_BITS; n; n--) {
1273                         hash = (hash << VALUE_HASH_SHIFT) ^
1274                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1275                                le32_to_cpu(*value++);
1276                 }
1277         }
1278         entry->e_hash = cpu_to_le32(hash);
1279 }
1280
1281 #undef NAME_HASH_SHIFT
1282 #undef VALUE_HASH_SHIFT
1283
1284 #define BLOCK_HASH_SHIFT 16
1285
1286 /*
1287  * ext3_xattr_rehash()
1288  *
1289  * Re-compute the extended attribute hash value after an entry has changed.
1290  */
1291 static void ext3_xattr_rehash(struct ext3_xattr_header *header,
1292                               struct ext3_xattr_entry *entry)
1293 {
1294         struct ext3_xattr_entry *here;
1295         __u32 hash = 0;
1296
1297         ext3_xattr_hash_entry(header, entry);
1298         here = ENTRY(header+1);
1299         while (!IS_LAST_ENTRY(here)) {
1300                 if (!here->e_hash) {
1301                         /* Block is not shared if an entry's hash value == 0 */
1302                         hash = 0;
1303                         break;
1304                 }
1305                 hash = (hash << BLOCK_HASH_SHIFT) ^
1306                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1307                        le32_to_cpu(here->e_hash);
1308                 here = EXT3_XATTR_NEXT(here);
1309         }
1310         header->h_hash = cpu_to_le32(hash);
1311 }
1312
1313 #undef BLOCK_HASH_SHIFT
1314
1315 int __init
1316 init_ext3_xattr(void)
1317 {
1318         ext3_xattr_cache = mb_cache_create("ext3_xattr", 6);
1319         if (!ext3_xattr_cache)
1320                 return -ENOMEM;
1321         return 0;
1322 }
1323
1324 void
1325 exit_ext3_xattr(void)
1326 {
1327         if (ext3_xattr_cache)
1328                 mb_cache_destroy(ext3_xattr_cache);
1329         ext3_xattr_cache = NULL;
1330 }