reiserfs: fixup xattr_root caching
[linux-2.6.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 <linux/init.h>
54 #include <linux/fs.h>
55 #include <linux/slab.h>
56 #include <linux/ext3_jbd.h>
57 #include <linux/ext3_fs.h>
58 #include <linux/mbcache.h>
59 #include <linux/quotaops.h>
60 #include <linux/rwsem.h>
61 #include "xattr.h"
62 #include "acl.h"
63
64 #define BHDR(bh) ((struct ext3_xattr_header *)((bh)->b_data))
65 #define ENTRY(ptr) ((struct ext3_xattr_entry *)(ptr))
66 #define BFIRST(bh) ENTRY(BHDR(bh)+1)
67 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
68
69 #define IHDR(inode, raw_inode) \
70         ((struct ext3_xattr_ibody_header *) \
71                 ((void *)raw_inode + \
72                  EXT3_GOOD_OLD_INODE_SIZE + \
73                  EXT3_I(inode)->i_extra_isize))
74 #define IFIRST(hdr) ((struct ext3_xattr_entry *)((hdr)+1))
75
76 #ifdef EXT3_XATTR_DEBUG
77 # define ea_idebug(inode, f...) do { \
78                 printk(KERN_DEBUG "inode %s:%lu: ", \
79                         inode->i_sb->s_id, inode->i_ino); \
80                 printk(f); \
81                 printk("\n"); \
82         } while (0)
83 # define ea_bdebug(bh, f...) do { \
84                 char b[BDEVNAME_SIZE]; \
85                 printk(KERN_DEBUG "block %s:%lu: ", \
86                         bdevname(bh->b_bdev, b), \
87                         (unsigned long) bh->b_blocknr); \
88                 printk(f); \
89                 printk("\n"); \
90         } while (0)
91 #else
92 # define ea_idebug(f...)
93 # define ea_bdebug(f...)
94 #endif
95
96 static void ext3_xattr_cache_insert(struct buffer_head *);
97 static struct buffer_head *ext3_xattr_cache_find(struct inode *,
98                                                  struct ext3_xattr_header *,
99                                                  struct mb_cache_entry **);
100 static void ext3_xattr_rehash(struct ext3_xattr_header *,
101                               struct ext3_xattr_entry *);
102 static int ext3_xattr_list(struct inode *inode, char *buffer,
103                            size_t buffer_size);
104
105 static struct mb_cache *ext3_xattr_cache;
106
107 static struct xattr_handler *ext3_xattr_handler_map[] = {
108         [EXT3_XATTR_INDEX_USER]              = &ext3_xattr_user_handler,
109 #ifdef CONFIG_EXT3_FS_POSIX_ACL
110         [EXT3_XATTR_INDEX_POSIX_ACL_ACCESS]  = &ext3_xattr_acl_access_handler,
111         [EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext3_xattr_acl_default_handler,
112 #endif
113         [EXT3_XATTR_INDEX_TRUSTED]           = &ext3_xattr_trusted_handler,
114 #ifdef CONFIG_EXT3_FS_SECURITY
115         [EXT3_XATTR_INDEX_SECURITY]          = &ext3_xattr_security_handler,
116 #endif
117 };
118
119 struct xattr_handler *ext3_xattr_handlers[] = {
120         &ext3_xattr_user_handler,
121         &ext3_xattr_trusted_handler,
122 #ifdef CONFIG_EXT3_FS_POSIX_ACL
123         &ext3_xattr_acl_access_handler,
124         &ext3_xattr_acl_default_handler,
125 #endif
126 #ifdef CONFIG_EXT3_FS_SECURITY
127         &ext3_xattr_security_handler,
128 #endif
129         NULL
130 };
131
132 static inline struct xattr_handler *
133 ext3_xattr_handler(int name_index)
134 {
135         struct xattr_handler *handler = NULL;
136
137         if (name_index > 0 && name_index < ARRAY_SIZE(ext3_xattr_handler_map))
138                 handler = ext3_xattr_handler_map[name_index];
139         return handler;
140 }
141
142 /*
143  * Inode operation listxattr()
144  *
145  * dentry->d_inode->i_mutex: don't care
146  */
147 ssize_t
148 ext3_listxattr(struct dentry *dentry, char *buffer, size_t size)
149 {
150         return ext3_xattr_list(dentry->d_inode, buffer, size);
151 }
152
153 static int
154 ext3_xattr_check_names(struct ext3_xattr_entry *entry, void *end)
155 {
156         while (!IS_LAST_ENTRY(entry)) {
157                 struct ext3_xattr_entry *next = EXT3_XATTR_NEXT(entry);
158                 if ((void *)next >= end)
159                         return -EIO;
160                 entry = next;
161         }
162         return 0;
163 }
164
165 static inline int
166 ext3_xattr_check_block(struct buffer_head *bh)
167 {
168         int error;
169
170         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
171             BHDR(bh)->h_blocks != cpu_to_le32(1))
172                 return -EIO;
173         error = ext3_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
174         return error;
175 }
176
177 static inline int
178 ext3_xattr_check_entry(struct ext3_xattr_entry *entry, size_t size)
179 {
180         size_t value_size = le32_to_cpu(entry->e_value_size);
181
182         if (entry->e_value_block != 0 || value_size > size ||
183             le16_to_cpu(entry->e_value_offs) + value_size > size)
184                 return -EIO;
185         return 0;
186 }
187
188 static int
189 ext3_xattr_find_entry(struct ext3_xattr_entry **pentry, int name_index,
190                       const char *name, size_t size, int sorted)
191 {
192         struct ext3_xattr_entry *entry;
193         size_t name_len;
194         int cmp = 1;
195
196         if (name == NULL)
197                 return -EINVAL;
198         name_len = strlen(name);
199         entry = *pentry;
200         for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
201                 cmp = name_index - entry->e_name_index;
202                 if (!cmp)
203                         cmp = name_len - entry->e_name_len;
204                 if (!cmp)
205                         cmp = memcmp(name, entry->e_name, name_len);
206                 if (cmp <= 0 && (sorted || cmp == 0))
207                         break;
208         }
209         *pentry = entry;
210         if (!cmp && ext3_xattr_check_entry(entry, size))
211                         return -EIO;
212         return cmp ? -ENODATA : 0;
213 }
214
215 static int
216 ext3_xattr_block_get(struct inode *inode, int name_index, const char *name,
217                      void *buffer, size_t buffer_size)
218 {
219         struct buffer_head *bh = NULL;
220         struct ext3_xattr_entry *entry;
221         size_t size;
222         int error;
223
224         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
225                   name_index, name, buffer, (long)buffer_size);
226
227         error = -ENODATA;
228         if (!EXT3_I(inode)->i_file_acl)
229                 goto cleanup;
230         ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
231         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
232         if (!bh)
233                 goto cleanup;
234         ea_bdebug(bh, "b_count=%d, refcount=%d",
235                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
236         if (ext3_xattr_check_block(bh)) {
237 bad_block:      ext3_error(inode->i_sb, __func__,
238                            "inode %lu: bad block "E3FSBLK, inode->i_ino,
239                            EXT3_I(inode)->i_file_acl);
240                 error = -EIO;
241                 goto cleanup;
242         }
243         ext3_xattr_cache_insert(bh);
244         entry = BFIRST(bh);
245         error = ext3_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
246         if (error == -EIO)
247                 goto bad_block;
248         if (error)
249                 goto cleanup;
250         size = le32_to_cpu(entry->e_value_size);
251         if (buffer) {
252                 error = -ERANGE;
253                 if (size > buffer_size)
254                         goto cleanup;
255                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
256                        size);
257         }
258         error = size;
259
260 cleanup:
261         brelse(bh);
262         return error;
263 }
264
265 static int
266 ext3_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
267                      void *buffer, size_t buffer_size)
268 {
269         struct ext3_xattr_ibody_header *header;
270         struct ext3_xattr_entry *entry;
271         struct ext3_inode *raw_inode;
272         struct ext3_iloc iloc;
273         size_t size;
274         void *end;
275         int error;
276
277         if (!(EXT3_I(inode)->i_state & EXT3_STATE_XATTR))
278                 return -ENODATA;
279         error = ext3_get_inode_loc(inode, &iloc);
280         if (error)
281                 return error;
282         raw_inode = ext3_raw_inode(&iloc);
283         header = IHDR(inode, raw_inode);
284         entry = IFIRST(header);
285         end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
286         error = ext3_xattr_check_names(entry, end);
287         if (error)
288                 goto cleanup;
289         error = ext3_xattr_find_entry(&entry, name_index, name,
290                                       end - (void *)entry, 0);
291         if (error)
292                 goto cleanup;
293         size = le32_to_cpu(entry->e_value_size);
294         if (buffer) {
295                 error = -ERANGE;
296                 if (size > buffer_size)
297                         goto cleanup;
298                 memcpy(buffer, (void *)IFIRST(header) +
299                        le16_to_cpu(entry->e_value_offs), size);
300         }
301         error = size;
302
303 cleanup:
304         brelse(iloc.bh);
305         return error;
306 }
307
308 /*
309  * ext3_xattr_get()
310  *
311  * Copy an extended attribute into the buffer
312  * provided, or compute the buffer size required.
313  * Buffer is NULL to compute the size of the buffer required.
314  *
315  * Returns a negative error number on failure, or the number of bytes
316  * used / required on success.
317  */
318 int
319 ext3_xattr_get(struct inode *inode, int name_index, const char *name,
320                void *buffer, size_t buffer_size)
321 {
322         int error;
323
324         down_read(&EXT3_I(inode)->xattr_sem);
325         error = ext3_xattr_ibody_get(inode, name_index, name, buffer,
326                                      buffer_size);
327         if (error == -ENODATA)
328                 error = ext3_xattr_block_get(inode, name_index, name, buffer,
329                                              buffer_size);
330         up_read(&EXT3_I(inode)->xattr_sem);
331         return error;
332 }
333
334 static int
335 ext3_xattr_list_entries(struct inode *inode, struct ext3_xattr_entry *entry,
336                         char *buffer, size_t buffer_size)
337 {
338         size_t rest = buffer_size;
339
340         for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
341                 struct xattr_handler *handler =
342                         ext3_xattr_handler(entry->e_name_index);
343
344                 if (handler) {
345                         size_t size = handler->list(inode, buffer, rest,
346                                                     entry->e_name,
347                                                     entry->e_name_len);
348                         if (buffer) {
349                                 if (size > rest)
350                                         return -ERANGE;
351                                 buffer += size;
352                         }
353                         rest -= size;
354                 }
355         }
356         return buffer_size - rest;
357 }
358
359 static int
360 ext3_xattr_block_list(struct inode *inode, char *buffer, size_t buffer_size)
361 {
362         struct buffer_head *bh = NULL;
363         int error;
364
365         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
366                   buffer, (long)buffer_size);
367
368         error = 0;
369         if (!EXT3_I(inode)->i_file_acl)
370                 goto cleanup;
371         ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
372         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
373         error = -EIO;
374         if (!bh)
375                 goto cleanup;
376         ea_bdebug(bh, "b_count=%d, refcount=%d",
377                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
378         if (ext3_xattr_check_block(bh)) {
379                 ext3_error(inode->i_sb, __func__,
380                            "inode %lu: bad block "E3FSBLK, inode->i_ino,
381                            EXT3_I(inode)->i_file_acl);
382                 error = -EIO;
383                 goto cleanup;
384         }
385         ext3_xattr_cache_insert(bh);
386         error = ext3_xattr_list_entries(inode, BFIRST(bh), buffer, buffer_size);
387
388 cleanup:
389         brelse(bh);
390
391         return error;
392 }
393
394 static int
395 ext3_xattr_ibody_list(struct inode *inode, char *buffer, size_t buffer_size)
396 {
397         struct ext3_xattr_ibody_header *header;
398         struct ext3_inode *raw_inode;
399         struct ext3_iloc iloc;
400         void *end;
401         int error;
402
403         if (!(EXT3_I(inode)->i_state & EXT3_STATE_XATTR))
404                 return 0;
405         error = ext3_get_inode_loc(inode, &iloc);
406         if (error)
407                 return error;
408         raw_inode = ext3_raw_inode(&iloc);
409         header = IHDR(inode, raw_inode);
410         end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
411         error = ext3_xattr_check_names(IFIRST(header), end);
412         if (error)
413                 goto cleanup;
414         error = ext3_xattr_list_entries(inode, IFIRST(header),
415                                         buffer, buffer_size);
416
417 cleanup:
418         brelse(iloc.bh);
419         return error;
420 }
421
422 /*
423  * ext3_xattr_list()
424  *
425  * Copy a list of attribute names into the buffer
426  * provided, or compute the buffer size required.
427  * Buffer is NULL to compute the size of the buffer required.
428  *
429  * Returns a negative error number on failure, or the number of bytes
430  * used / required on success.
431  */
432 static int
433 ext3_xattr_list(struct inode *inode, char *buffer, size_t buffer_size)
434 {
435         int i_error, b_error;
436
437         down_read(&EXT3_I(inode)->xattr_sem);
438         i_error = ext3_xattr_ibody_list(inode, buffer, buffer_size);
439         if (i_error < 0) {
440                 b_error = 0;
441         } else {
442                 if (buffer) {
443                         buffer += i_error;
444                         buffer_size -= i_error;
445                 }
446                 b_error = ext3_xattr_block_list(inode, buffer, buffer_size);
447                 if (b_error < 0)
448                         i_error = 0;
449         }
450         up_read(&EXT3_I(inode)->xattr_sem);
451         return i_error + b_error;
452 }
453
454 /*
455  * If the EXT3_FEATURE_COMPAT_EXT_ATTR feature of this file system is
456  * not set, set it.
457  */
458 static void ext3_xattr_update_super_block(handle_t *handle,
459                                           struct super_block *sb)
460 {
461         if (EXT3_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR))
462                 return;
463
464         if (ext3_journal_get_write_access(handle, EXT3_SB(sb)->s_sbh) == 0) {
465                 EXT3_SET_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR);
466                 sb->s_dirt = 1;
467                 ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
468         }
469 }
470
471 /*
472  * Release the xattr block BH: If the reference count is > 1, decrement
473  * it; otherwise free the block.
474  */
475 static void
476 ext3_xattr_release_block(handle_t *handle, struct inode *inode,
477                          struct buffer_head *bh)
478 {
479         struct mb_cache_entry *ce = NULL;
480         int error = 0;
481
482         ce = mb_cache_entry_get(ext3_xattr_cache, bh->b_bdev, bh->b_blocknr);
483         error = ext3_journal_get_write_access(handle, bh);
484         if (error)
485                  goto out;
486
487         lock_buffer(bh);
488
489         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
490                 ea_bdebug(bh, "refcount now=0; freeing");
491                 if (ce)
492                         mb_cache_entry_free(ce);
493                 ext3_free_blocks(handle, inode, bh->b_blocknr, 1);
494                 get_bh(bh);
495                 ext3_forget(handle, 1, inode, bh, bh->b_blocknr);
496         } else {
497                 le32_add_cpu(&BHDR(bh)->h_refcount, -1);
498                 error = ext3_journal_dirty_metadata(handle, bh);
499                 if (IS_SYNC(inode))
500                         handle->h_sync = 1;
501                 vfs_dq_free_block(inode, 1);
502                 ea_bdebug(bh, "refcount now=%d; releasing",
503                           le32_to_cpu(BHDR(bh)->h_refcount));
504                 if (ce)
505                         mb_cache_entry_release(ce);
506         }
507         unlock_buffer(bh);
508 out:
509         ext3_std_error(inode->i_sb, error);
510         return;
511 }
512
513 struct ext3_xattr_info {
514         int name_index;
515         const char *name;
516         const void *value;
517         size_t value_len;
518 };
519
520 struct ext3_xattr_search {
521         struct ext3_xattr_entry *first;
522         void *base;
523         void *end;
524         struct ext3_xattr_entry *here;
525         int not_found;
526 };
527
528 static int
529 ext3_xattr_set_entry(struct ext3_xattr_info *i, struct ext3_xattr_search *s)
530 {
531         struct ext3_xattr_entry *last;
532         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
533
534         /* Compute min_offs and last. */
535         last = s->first;
536         for (; !IS_LAST_ENTRY(last); last = EXT3_XATTR_NEXT(last)) {
537                 if (!last->e_value_block && last->e_value_size) {
538                         size_t offs = le16_to_cpu(last->e_value_offs);
539                         if (offs < min_offs)
540                                 min_offs = offs;
541                 }
542         }
543         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
544         if (!s->not_found) {
545                 if (!s->here->e_value_block && s->here->e_value_size) {
546                         size_t size = le32_to_cpu(s->here->e_value_size);
547                         free += EXT3_XATTR_SIZE(size);
548                 }
549                 free += EXT3_XATTR_LEN(name_len);
550         }
551         if (i->value) {
552                 if (free < EXT3_XATTR_SIZE(i->value_len) ||
553                     free < EXT3_XATTR_LEN(name_len) +
554                            EXT3_XATTR_SIZE(i->value_len))
555                         return -ENOSPC;
556         }
557
558         if (i->value && s->not_found) {
559                 /* Insert the new name. */
560                 size_t size = EXT3_XATTR_LEN(name_len);
561                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
562                 memmove((void *)s->here + size, s->here, rest);
563                 memset(s->here, 0, size);
564                 s->here->e_name_index = i->name_index;
565                 s->here->e_name_len = name_len;
566                 memcpy(s->here->e_name, i->name, name_len);
567         } else {
568                 if (!s->here->e_value_block && s->here->e_value_size) {
569                         void *first_val = s->base + min_offs;
570                         size_t offs = le16_to_cpu(s->here->e_value_offs);
571                         void *val = s->base + offs;
572                         size_t size = EXT3_XATTR_SIZE(
573                                 le32_to_cpu(s->here->e_value_size));
574
575                         if (i->value && size == EXT3_XATTR_SIZE(i->value_len)) {
576                                 /* The old and the new value have the same
577                                    size. Just replace. */
578                                 s->here->e_value_size =
579                                         cpu_to_le32(i->value_len);
580                                 memset(val + size - EXT3_XATTR_PAD, 0,
581                                        EXT3_XATTR_PAD); /* Clear pad bytes. */
582                                 memcpy(val, i->value, i->value_len);
583                                 return 0;
584                         }
585
586                         /* Remove the old value. */
587                         memmove(first_val + size, first_val, val - first_val);
588                         memset(first_val, 0, size);
589                         s->here->e_value_size = 0;
590                         s->here->e_value_offs = 0;
591                         min_offs += size;
592
593                         /* Adjust all value offsets. */
594                         last = s->first;
595                         while (!IS_LAST_ENTRY(last)) {
596                                 size_t o = le16_to_cpu(last->e_value_offs);
597                                 if (!last->e_value_block &&
598                                     last->e_value_size && o < offs)
599                                         last->e_value_offs =
600                                                 cpu_to_le16(o + size);
601                                 last = EXT3_XATTR_NEXT(last);
602                         }
603                 }
604                 if (!i->value) {
605                         /* Remove the old name. */
606                         size_t size = EXT3_XATTR_LEN(name_len);
607                         last = ENTRY((void *)last - size);
608                         memmove(s->here, (void *)s->here + size,
609                                 (void *)last - (void *)s->here + sizeof(__u32));
610                         memset(last, 0, size);
611                 }
612         }
613
614         if (i->value) {
615                 /* Insert the new value. */
616                 s->here->e_value_size = cpu_to_le32(i->value_len);
617                 if (i->value_len) {
618                         size_t size = EXT3_XATTR_SIZE(i->value_len);
619                         void *val = s->base + min_offs - size;
620                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
621                         memset(val + size - EXT3_XATTR_PAD, 0,
622                                EXT3_XATTR_PAD); /* Clear the pad bytes. */
623                         memcpy(val, i->value, i->value_len);
624                 }
625         }
626         return 0;
627 }
628
629 struct ext3_xattr_block_find {
630         struct ext3_xattr_search s;
631         struct buffer_head *bh;
632 };
633
634 static int
635 ext3_xattr_block_find(struct inode *inode, struct ext3_xattr_info *i,
636                       struct ext3_xattr_block_find *bs)
637 {
638         struct super_block *sb = inode->i_sb;
639         int error;
640
641         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
642                   i->name_index, i->name, i->value, (long)i->value_len);
643
644         if (EXT3_I(inode)->i_file_acl) {
645                 /* The inode already has an extended attribute block. */
646                 bs->bh = sb_bread(sb, EXT3_I(inode)->i_file_acl);
647                 error = -EIO;
648                 if (!bs->bh)
649                         goto cleanup;
650                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
651                         atomic_read(&(bs->bh->b_count)),
652                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
653                 if (ext3_xattr_check_block(bs->bh)) {
654                         ext3_error(sb, __func__,
655                                 "inode %lu: bad block "E3FSBLK, inode->i_ino,
656                                 EXT3_I(inode)->i_file_acl);
657                         error = -EIO;
658                         goto cleanup;
659                 }
660                 /* Find the named attribute. */
661                 bs->s.base = BHDR(bs->bh);
662                 bs->s.first = BFIRST(bs->bh);
663                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
664                 bs->s.here = bs->s.first;
665                 error = ext3_xattr_find_entry(&bs->s.here, i->name_index,
666                                               i->name, bs->bh->b_size, 1);
667                 if (error && error != -ENODATA)
668                         goto cleanup;
669                 bs->s.not_found = error;
670         }
671         error = 0;
672
673 cleanup:
674         return error;
675 }
676
677 static int
678 ext3_xattr_block_set(handle_t *handle, struct inode *inode,
679                      struct ext3_xattr_info *i,
680                      struct ext3_xattr_block_find *bs)
681 {
682         struct super_block *sb = inode->i_sb;
683         struct buffer_head *new_bh = NULL;
684         struct ext3_xattr_search *s = &bs->s;
685         struct mb_cache_entry *ce = NULL;
686         int error = 0;
687
688 #define header(x) ((struct ext3_xattr_header *)(x))
689
690         if (i->value && i->value_len > sb->s_blocksize)
691                 return -ENOSPC;
692         if (s->base) {
693                 ce = mb_cache_entry_get(ext3_xattr_cache, bs->bh->b_bdev,
694                                         bs->bh->b_blocknr);
695                 error = ext3_journal_get_write_access(handle, bs->bh);
696                 if (error)
697                         goto cleanup;
698                 lock_buffer(bs->bh);
699
700                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
701                         if (ce) {
702                                 mb_cache_entry_free(ce);
703                                 ce = NULL;
704                         }
705                         ea_bdebug(bs->bh, "modifying in-place");
706                         error = ext3_xattr_set_entry(i, s);
707                         if (!error) {
708                                 if (!IS_LAST_ENTRY(s->first))
709                                         ext3_xattr_rehash(header(s->base),
710                                                           s->here);
711                                 ext3_xattr_cache_insert(bs->bh);
712                         }
713                         unlock_buffer(bs->bh);
714                         if (error == -EIO)
715                                 goto bad_block;
716                         if (!error)
717                                 error = ext3_journal_dirty_metadata(handle,
718                                                                     bs->bh);
719                         if (error)
720                                 goto cleanup;
721                         goto inserted;
722                 } else {
723                         int offset = (char *)s->here - bs->bh->b_data;
724
725                         unlock_buffer(bs->bh);
726                         journal_release_buffer(handle, bs->bh);
727
728                         if (ce) {
729                                 mb_cache_entry_release(ce);
730                                 ce = NULL;
731                         }
732                         ea_bdebug(bs->bh, "cloning");
733                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
734                         error = -ENOMEM;
735                         if (s->base == NULL)
736                                 goto cleanup;
737                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
738                         s->first = ENTRY(header(s->base)+1);
739                         header(s->base)->h_refcount = cpu_to_le32(1);
740                         s->here = ENTRY(s->base + offset);
741                         s->end = s->base + bs->bh->b_size;
742                 }
743         } else {
744                 /* Allocate a buffer where we construct the new block. */
745                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
746                 /* assert(header == s->base) */
747                 error = -ENOMEM;
748                 if (s->base == NULL)
749                         goto cleanup;
750                 header(s->base)->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
751                 header(s->base)->h_blocks = cpu_to_le32(1);
752                 header(s->base)->h_refcount = cpu_to_le32(1);
753                 s->first = ENTRY(header(s->base)+1);
754                 s->here = ENTRY(header(s->base)+1);
755                 s->end = s->base + sb->s_blocksize;
756         }
757
758         error = ext3_xattr_set_entry(i, s);
759         if (error == -EIO)
760                 goto bad_block;
761         if (error)
762                 goto cleanup;
763         if (!IS_LAST_ENTRY(s->first))
764                 ext3_xattr_rehash(header(s->base), s->here);
765
766 inserted:
767         if (!IS_LAST_ENTRY(s->first)) {
768                 new_bh = ext3_xattr_cache_find(inode, header(s->base), &ce);
769                 if (new_bh) {
770                         /* We found an identical block in the cache. */
771                         if (new_bh == bs->bh)
772                                 ea_bdebug(new_bh, "keeping");
773                         else {
774                                 /* The old block is released after updating
775                                    the inode. */
776                                 error = -EDQUOT;
777                                 if (vfs_dq_alloc_block(inode, 1))
778                                         goto cleanup;
779                                 error = ext3_journal_get_write_access(handle,
780                                                                       new_bh);
781                                 if (error)
782                                         goto cleanup_dquot;
783                                 lock_buffer(new_bh);
784                                 le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
785                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
786                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
787                                 unlock_buffer(new_bh);
788                                 error = ext3_journal_dirty_metadata(handle,
789                                                                     new_bh);
790                                 if (error)
791                                         goto cleanup_dquot;
792                         }
793                         mb_cache_entry_release(ce);
794                         ce = NULL;
795                 } else if (bs->bh && s->base == bs->bh->b_data) {
796                         /* We were modifying this block in-place. */
797                         ea_bdebug(bs->bh, "keeping this block");
798                         new_bh = bs->bh;
799                         get_bh(new_bh);
800                 } else {
801                         /* We need to allocate a new block */
802                         ext3_fsblk_t goal = ext3_group_first_block_no(sb,
803                                                 EXT3_I(inode)->i_block_group);
804                         ext3_fsblk_t block = ext3_new_block(handle, inode,
805                                                         goal, &error);
806                         if (error)
807                                 goto cleanup;
808                         ea_idebug(inode, "creating block %d", block);
809
810                         new_bh = sb_getblk(sb, block);
811                         if (!new_bh) {
812 getblk_failed:
813                                 ext3_free_blocks(handle, inode, block, 1);
814                                 error = -EIO;
815                                 goto cleanup;
816                         }
817                         lock_buffer(new_bh);
818                         error = ext3_journal_get_create_access(handle, new_bh);
819                         if (error) {
820                                 unlock_buffer(new_bh);
821                                 goto getblk_failed;
822                         }
823                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
824                         set_buffer_uptodate(new_bh);
825                         unlock_buffer(new_bh);
826                         ext3_xattr_cache_insert(new_bh);
827                         error = ext3_journal_dirty_metadata(handle, new_bh);
828                         if (error)
829                                 goto cleanup;
830                 }
831         }
832
833         /* Update the inode. */
834         EXT3_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
835
836         /* Drop the previous xattr block. */
837         if (bs->bh && bs->bh != new_bh)
838                 ext3_xattr_release_block(handle, inode, bs->bh);
839         error = 0;
840
841 cleanup:
842         if (ce)
843                 mb_cache_entry_release(ce);
844         brelse(new_bh);
845         if (!(bs->bh && s->base == bs->bh->b_data))
846                 kfree(s->base);
847
848         return error;
849
850 cleanup_dquot:
851         vfs_dq_free_block(inode, 1);
852         goto cleanup;
853
854 bad_block:
855         ext3_error(inode->i_sb, __func__,
856                    "inode %lu: bad block "E3FSBLK, inode->i_ino,
857                    EXT3_I(inode)->i_file_acl);
858         goto cleanup;
859
860 #undef header
861 }
862
863 struct ext3_xattr_ibody_find {
864         struct ext3_xattr_search s;
865         struct ext3_iloc iloc;
866 };
867
868 static int
869 ext3_xattr_ibody_find(struct inode *inode, struct ext3_xattr_info *i,
870                       struct ext3_xattr_ibody_find *is)
871 {
872         struct ext3_xattr_ibody_header *header;
873         struct ext3_inode *raw_inode;
874         int error;
875
876         if (EXT3_I(inode)->i_extra_isize == 0)
877                 return 0;
878         raw_inode = ext3_raw_inode(&is->iloc);
879         header = IHDR(inode, raw_inode);
880         is->s.base = is->s.first = IFIRST(header);
881         is->s.here = is->s.first;
882         is->s.end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
883         if (EXT3_I(inode)->i_state & EXT3_STATE_XATTR) {
884                 error = ext3_xattr_check_names(IFIRST(header), is->s.end);
885                 if (error)
886                         return error;
887                 /* Find the named attribute. */
888                 error = ext3_xattr_find_entry(&is->s.here, i->name_index,
889                                               i->name, is->s.end -
890                                               (void *)is->s.base, 0);
891                 if (error && error != -ENODATA)
892                         return error;
893                 is->s.not_found = error;
894         }
895         return 0;
896 }
897
898 static int
899 ext3_xattr_ibody_set(handle_t *handle, struct inode *inode,
900                      struct ext3_xattr_info *i,
901                      struct ext3_xattr_ibody_find *is)
902 {
903         struct ext3_xattr_ibody_header *header;
904         struct ext3_xattr_search *s = &is->s;
905         int error;
906
907         if (EXT3_I(inode)->i_extra_isize == 0)
908                 return -ENOSPC;
909         error = ext3_xattr_set_entry(i, s);
910         if (error)
911                 return error;
912         header = IHDR(inode, ext3_raw_inode(&is->iloc));
913         if (!IS_LAST_ENTRY(s->first)) {
914                 header->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
915                 EXT3_I(inode)->i_state |= EXT3_STATE_XATTR;
916         } else {
917                 header->h_magic = cpu_to_le32(0);
918                 EXT3_I(inode)->i_state &= ~EXT3_STATE_XATTR;
919         }
920         return 0;
921 }
922
923 /*
924  * ext3_xattr_set_handle()
925  *
926  * Create, replace or remove an extended attribute for this inode. Buffer
927  * is NULL to remove an existing extended attribute, and non-NULL to
928  * either replace an existing extended attribute, or create a new extended
929  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
930  * specify that an extended attribute must exist and must not exist
931  * previous to the call, respectively.
932  *
933  * Returns 0, or a negative error number on failure.
934  */
935 int
936 ext3_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
937                       const char *name, const void *value, size_t value_len,
938                       int flags)
939 {
940         struct ext3_xattr_info i = {
941                 .name_index = name_index,
942                 .name = name,
943                 .value = value,
944                 .value_len = value_len,
945
946         };
947         struct ext3_xattr_ibody_find is = {
948                 .s = { .not_found = -ENODATA, },
949         };
950         struct ext3_xattr_block_find bs = {
951                 .s = { .not_found = -ENODATA, },
952         };
953         int error;
954
955         if (!name)
956                 return -EINVAL;
957         if (strlen(name) > 255)
958                 return -ERANGE;
959         down_write(&EXT3_I(inode)->xattr_sem);
960         error = ext3_get_inode_loc(inode, &is.iloc);
961         if (error)
962                 goto cleanup;
963
964         if (EXT3_I(inode)->i_state & EXT3_STATE_NEW) {
965                 struct ext3_inode *raw_inode = ext3_raw_inode(&is.iloc);
966                 memset(raw_inode, 0, EXT3_SB(inode->i_sb)->s_inode_size);
967                 EXT3_I(inode)->i_state &= ~EXT3_STATE_NEW;
968         }
969
970         error = ext3_xattr_ibody_find(inode, &i, &is);
971         if (error)
972                 goto cleanup;
973         if (is.s.not_found)
974                 error = ext3_xattr_block_find(inode, &i, &bs);
975         if (error)
976                 goto cleanup;
977         if (is.s.not_found && bs.s.not_found) {
978                 error = -ENODATA;
979                 if (flags & XATTR_REPLACE)
980                         goto cleanup;
981                 error = 0;
982                 if (!value)
983                         goto cleanup;
984         } else {
985                 error = -EEXIST;
986                 if (flags & XATTR_CREATE)
987                         goto cleanup;
988         }
989         error = ext3_journal_get_write_access(handle, is.iloc.bh);
990         if (error)
991                 goto cleanup;
992         if (!value) {
993                 if (!is.s.not_found)
994                         error = ext3_xattr_ibody_set(handle, inode, &i, &is);
995                 else if (!bs.s.not_found)
996                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
997         } else {
998                 error = ext3_xattr_ibody_set(handle, inode, &i, &is);
999                 if (!error && !bs.s.not_found) {
1000                         i.value = NULL;
1001                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1002                 } else if (error == -ENOSPC) {
1003                         if (EXT3_I(inode)->i_file_acl && !bs.s.base) {
1004                                 error = ext3_xattr_block_find(inode, &i, &bs);
1005                                 if (error)
1006                                         goto cleanup;
1007                         }
1008                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1009                         if (error)
1010                                 goto cleanup;
1011                         if (!is.s.not_found) {
1012                                 i.value = NULL;
1013                                 error = ext3_xattr_ibody_set(handle, inode, &i,
1014                                                              &is);
1015                         }
1016                 }
1017         }
1018         if (!error) {
1019                 ext3_xattr_update_super_block(handle, inode->i_sb);
1020                 inode->i_ctime = CURRENT_TIME_SEC;
1021                 error = ext3_mark_iloc_dirty(handle, inode, &is.iloc);
1022                 /*
1023                  * The bh is consumed by ext3_mark_iloc_dirty, even with
1024                  * error != 0.
1025                  */
1026                 is.iloc.bh = NULL;
1027                 if (IS_SYNC(inode))
1028                         handle->h_sync = 1;
1029         }
1030
1031 cleanup:
1032         brelse(is.iloc.bh);
1033         brelse(bs.bh);
1034         up_write(&EXT3_I(inode)->xattr_sem);
1035         return error;
1036 }
1037
1038 /*
1039  * ext3_xattr_set()
1040  *
1041  * Like ext3_xattr_set_handle, but start from an inode. This extended
1042  * attribute modification is a filesystem transaction by itself.
1043  *
1044  * Returns 0, or a negative error number on failure.
1045  */
1046 int
1047 ext3_xattr_set(struct inode *inode, int name_index, const char *name,
1048                const void *value, size_t value_len, int flags)
1049 {
1050         handle_t *handle;
1051         int error, retries = 0;
1052
1053 retry:
1054         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
1055         if (IS_ERR(handle)) {
1056                 error = PTR_ERR(handle);
1057         } else {
1058                 int error2;
1059
1060                 error = ext3_xattr_set_handle(handle, inode, name_index, name,
1061                                               value, value_len, flags);
1062                 error2 = ext3_journal_stop(handle);
1063                 if (error == -ENOSPC &&
1064                     ext3_should_retry_alloc(inode->i_sb, &retries))
1065                         goto retry;
1066                 if (error == 0)
1067                         error = error2;
1068         }
1069
1070         return error;
1071 }
1072
1073 /*
1074  * ext3_xattr_delete_inode()
1075  *
1076  * Free extended attribute resources associated with this inode. This
1077  * is called immediately before an inode is freed. We have exclusive
1078  * access to the inode.
1079  */
1080 void
1081 ext3_xattr_delete_inode(handle_t *handle, struct inode *inode)
1082 {
1083         struct buffer_head *bh = NULL;
1084
1085         if (!EXT3_I(inode)->i_file_acl)
1086                 goto cleanup;
1087         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
1088         if (!bh) {
1089                 ext3_error(inode->i_sb, __func__,
1090                         "inode %lu: block "E3FSBLK" read error", inode->i_ino,
1091                         EXT3_I(inode)->i_file_acl);
1092                 goto cleanup;
1093         }
1094         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
1095             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1096                 ext3_error(inode->i_sb, __func__,
1097                         "inode %lu: bad block "E3FSBLK, inode->i_ino,
1098                         EXT3_I(inode)->i_file_acl);
1099                 goto cleanup;
1100         }
1101         ext3_xattr_release_block(handle, inode, bh);
1102         EXT3_I(inode)->i_file_acl = 0;
1103
1104 cleanup:
1105         brelse(bh);
1106 }
1107
1108 /*
1109  * ext3_xattr_put_super()
1110  *
1111  * This is called when a file system is unmounted.
1112  */
1113 void
1114 ext3_xattr_put_super(struct super_block *sb)
1115 {
1116         mb_cache_shrink(sb->s_bdev);
1117 }
1118
1119 /*
1120  * ext3_xattr_cache_insert()
1121  *
1122  * Create a new entry in the extended attribute cache, and insert
1123  * it unless such an entry is already in the cache.
1124  *
1125  * Returns 0, or a negative error number on failure.
1126  */
1127 static void
1128 ext3_xattr_cache_insert(struct buffer_head *bh)
1129 {
1130         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1131         struct mb_cache_entry *ce;
1132         int error;
1133
1134         ce = mb_cache_entry_alloc(ext3_xattr_cache, GFP_NOFS);
1135         if (!ce) {
1136                 ea_bdebug(bh, "out of memory");
1137                 return;
1138         }
1139         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
1140         if (error) {
1141                 mb_cache_entry_free(ce);
1142                 if (error == -EBUSY) {
1143                         ea_bdebug(bh, "already in cache");
1144                         error = 0;
1145                 }
1146         } else {
1147                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1148                 mb_cache_entry_release(ce);
1149         }
1150 }
1151
1152 /*
1153  * ext3_xattr_cmp()
1154  *
1155  * Compare two extended attribute blocks for equality.
1156  *
1157  * Returns 0 if the blocks are equal, 1 if they differ, and
1158  * a negative error number on errors.
1159  */
1160 static int
1161 ext3_xattr_cmp(struct ext3_xattr_header *header1,
1162                struct ext3_xattr_header *header2)
1163 {
1164         struct ext3_xattr_entry *entry1, *entry2;
1165
1166         entry1 = ENTRY(header1+1);
1167         entry2 = ENTRY(header2+1);
1168         while (!IS_LAST_ENTRY(entry1)) {
1169                 if (IS_LAST_ENTRY(entry2))
1170                         return 1;
1171                 if (entry1->e_hash != entry2->e_hash ||
1172                     entry1->e_name_index != entry2->e_name_index ||
1173                     entry1->e_name_len != entry2->e_name_len ||
1174                     entry1->e_value_size != entry2->e_value_size ||
1175                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1176                         return 1;
1177                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1178                         return -EIO;
1179                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1180                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1181                            le32_to_cpu(entry1->e_value_size)))
1182                         return 1;
1183
1184                 entry1 = EXT3_XATTR_NEXT(entry1);
1185                 entry2 = EXT3_XATTR_NEXT(entry2);
1186         }
1187         if (!IS_LAST_ENTRY(entry2))
1188                 return 1;
1189         return 0;
1190 }
1191
1192 /*
1193  * ext3_xattr_cache_find()
1194  *
1195  * Find an identical extended attribute block.
1196  *
1197  * Returns a pointer to the block found, or NULL if such a block was
1198  * not found or an error occurred.
1199  */
1200 static struct buffer_head *
1201 ext3_xattr_cache_find(struct inode *inode, struct ext3_xattr_header *header,
1202                       struct mb_cache_entry **pce)
1203 {
1204         __u32 hash = le32_to_cpu(header->h_hash);
1205         struct mb_cache_entry *ce;
1206
1207         if (!header->h_hash)
1208                 return NULL;  /* never share */
1209         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1210 again:
1211         ce = mb_cache_entry_find_first(ext3_xattr_cache, 0,
1212                                        inode->i_sb->s_bdev, hash);
1213         while (ce) {
1214                 struct buffer_head *bh;
1215
1216                 if (IS_ERR(ce)) {
1217                         if (PTR_ERR(ce) == -EAGAIN)
1218                                 goto again;
1219                         break;
1220                 }
1221                 bh = sb_bread(inode->i_sb, ce->e_block);
1222                 if (!bh) {
1223                         ext3_error(inode->i_sb, __func__,
1224                                 "inode %lu: block %lu read error",
1225                                 inode->i_ino, (unsigned long) ce->e_block);
1226                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1227                                 EXT3_XATTR_REFCOUNT_MAX) {
1228                         ea_idebug(inode, "block %lu refcount %d>=%d",
1229                                   (unsigned long) ce->e_block,
1230                                   le32_to_cpu(BHDR(bh)->h_refcount),
1231                                           EXT3_XATTR_REFCOUNT_MAX);
1232                 } else if (ext3_xattr_cmp(header, BHDR(bh)) == 0) {
1233                         *pce = ce;
1234                         return bh;
1235                 }
1236                 brelse(bh);
1237                 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
1238         }
1239         return NULL;
1240 }
1241
1242 #define NAME_HASH_SHIFT 5
1243 #define VALUE_HASH_SHIFT 16
1244
1245 /*
1246  * ext3_xattr_hash_entry()
1247  *
1248  * Compute the hash of an extended attribute.
1249  */
1250 static inline void ext3_xattr_hash_entry(struct ext3_xattr_header *header,
1251                                          struct ext3_xattr_entry *entry)
1252 {
1253         __u32 hash = 0;
1254         char *name = entry->e_name;
1255         int n;
1256
1257         for (n=0; n < entry->e_name_len; n++) {
1258                 hash = (hash << NAME_HASH_SHIFT) ^
1259                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1260                        *name++;
1261         }
1262
1263         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1264                 __le32 *value = (__le32 *)((char *)header +
1265                         le16_to_cpu(entry->e_value_offs));
1266                 for (n = (le32_to_cpu(entry->e_value_size) +
1267                      EXT3_XATTR_ROUND) >> EXT3_XATTR_PAD_BITS; n; n--) {
1268                         hash = (hash << VALUE_HASH_SHIFT) ^
1269                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1270                                le32_to_cpu(*value++);
1271                 }
1272         }
1273         entry->e_hash = cpu_to_le32(hash);
1274 }
1275
1276 #undef NAME_HASH_SHIFT
1277 #undef VALUE_HASH_SHIFT
1278
1279 #define BLOCK_HASH_SHIFT 16
1280
1281 /*
1282  * ext3_xattr_rehash()
1283  *
1284  * Re-compute the extended attribute hash value after an entry has changed.
1285  */
1286 static void ext3_xattr_rehash(struct ext3_xattr_header *header,
1287                               struct ext3_xattr_entry *entry)
1288 {
1289         struct ext3_xattr_entry *here;
1290         __u32 hash = 0;
1291
1292         ext3_xattr_hash_entry(header, entry);
1293         here = ENTRY(header+1);
1294         while (!IS_LAST_ENTRY(here)) {
1295                 if (!here->e_hash) {
1296                         /* Block is not shared if an entry's hash value == 0 */
1297                         hash = 0;
1298                         break;
1299                 }
1300                 hash = (hash << BLOCK_HASH_SHIFT) ^
1301                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1302                        le32_to_cpu(here->e_hash);
1303                 here = EXT3_XATTR_NEXT(here);
1304         }
1305         header->h_hash = cpu_to_le32(hash);
1306 }
1307
1308 #undef BLOCK_HASH_SHIFT
1309
1310 int __init
1311 init_ext3_xattr(void)
1312 {
1313         ext3_xattr_cache = mb_cache_create("ext3_xattr", NULL,
1314                 sizeof(struct mb_cache_entry) +
1315                 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1316         if (!ext3_xattr_cache)
1317                 return -ENOMEM;
1318         return 0;
1319 }
1320
1321 void
1322 exit_ext3_xattr(void)
1323 {
1324         if (ext3_xattr_cache)
1325                 mb_cache_destroy(ext3_xattr_cache);
1326         ext3_xattr_cache = NULL;
1327 }