Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
[linux-2.6] / 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
103 static struct mb_cache *ext3_xattr_cache;
104
105 static struct xattr_handler *ext3_xattr_handler_map[] = {
106         [EXT3_XATTR_INDEX_USER]              = &ext3_xattr_user_handler,
107 #ifdef CONFIG_EXT3_FS_POSIX_ACL
108         [EXT3_XATTR_INDEX_POSIX_ACL_ACCESS]  = &ext3_xattr_acl_access_handler,
109         [EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext3_xattr_acl_default_handler,
110 #endif
111         [EXT3_XATTR_INDEX_TRUSTED]           = &ext3_xattr_trusted_handler,
112 #ifdef CONFIG_EXT3_FS_SECURITY
113         [EXT3_XATTR_INDEX_SECURITY]          = &ext3_xattr_security_handler,
114 #endif
115 };
116
117 struct xattr_handler *ext3_xattr_handlers[] = {
118         &ext3_xattr_user_handler,
119         &ext3_xattr_trusted_handler,
120 #ifdef CONFIG_EXT3_FS_POSIX_ACL
121         &ext3_xattr_acl_access_handler,
122         &ext3_xattr_acl_default_handler,
123 #endif
124 #ifdef CONFIG_EXT3_FS_SECURITY
125         &ext3_xattr_security_handler,
126 #endif
127         NULL
128 };
129
130 static inline struct xattr_handler *
131 ext3_xattr_handler(int name_index)
132 {
133         struct xattr_handler *handler = NULL;
134
135         if (name_index > 0 && name_index < ARRAY_SIZE(ext3_xattr_handler_map))
136                 handler = ext3_xattr_handler_map[name_index];
137         return handler;
138 }
139
140 /*
141  * Inode operation listxattr()
142  *
143  * dentry->d_inode->i_mutex: don't care
144  */
145 ssize_t
146 ext3_listxattr(struct dentry *dentry, char *buffer, size_t size)
147 {
148         return ext3_xattr_list(dentry->d_inode, buffer, size);
149 }
150
151 static int
152 ext3_xattr_check_names(struct ext3_xattr_entry *entry, void *end)
153 {
154         while (!IS_LAST_ENTRY(entry)) {
155                 struct ext3_xattr_entry *next = EXT3_XATTR_NEXT(entry);
156                 if ((void *)next >= end)
157                         return -EIO;
158                 entry = next;
159         }
160         return 0;
161 }
162
163 static inline int
164 ext3_xattr_check_block(struct buffer_head *bh)
165 {
166         int error;
167
168         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
169             BHDR(bh)->h_blocks != cpu_to_le32(1))
170                 return -EIO;
171         error = ext3_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
172         return error;
173 }
174
175 static inline int
176 ext3_xattr_check_entry(struct ext3_xattr_entry *entry, size_t size)
177 {
178         size_t value_size = le32_to_cpu(entry->e_value_size);
179
180         if (entry->e_value_block != 0 || value_size > size ||
181             le16_to_cpu(entry->e_value_offs) + value_size > size)
182                 return -EIO;
183         return 0;
184 }
185
186 static int
187 ext3_xattr_find_entry(struct ext3_xattr_entry **pentry, int name_index,
188                       const char *name, size_t size, int sorted)
189 {
190         struct ext3_xattr_entry *entry;
191         size_t name_len;
192         int cmp = 1;
193
194         if (name == NULL)
195                 return -EINVAL;
196         name_len = strlen(name);
197         entry = *pentry;
198         for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
199                 cmp = name_index - entry->e_name_index;
200                 if (!cmp)
201                         cmp = name_len - entry->e_name_len;
202                 if (!cmp)
203                         cmp = memcmp(name, entry->e_name, name_len);
204                 if (cmp <= 0 && (sorted || cmp == 0))
205                         break;
206         }
207         *pentry = entry;
208         if (!cmp && ext3_xattr_check_entry(entry, size))
209                         return -EIO;
210         return cmp ? -ENODATA : 0;
211 }
212
213 static int
214 ext3_xattr_block_get(struct inode *inode, int name_index, const char *name,
215                      void *buffer, size_t buffer_size)
216 {
217         struct buffer_head *bh = NULL;
218         struct ext3_xattr_entry *entry;
219         size_t size;
220         int error;
221
222         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
223                   name_index, name, buffer, (long)buffer_size);
224
225         error = -ENODATA;
226         if (!EXT3_I(inode)->i_file_acl)
227                 goto cleanup;
228         ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
229         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
230         if (!bh)
231                 goto cleanup;
232         ea_bdebug(bh, "b_count=%d, refcount=%d",
233                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
234         if (ext3_xattr_check_block(bh)) {
235 bad_block:      ext3_error(inode->i_sb, __FUNCTION__,
236                            "inode %lu: bad block "E3FSBLK, inode->i_ino,
237                            EXT3_I(inode)->i_file_acl);
238                 error = -EIO;
239                 goto cleanup;
240         }
241         ext3_xattr_cache_insert(bh);
242         entry = BFIRST(bh);
243         error = ext3_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
244         if (error == -EIO)
245                 goto bad_block;
246         if (error)
247                 goto cleanup;
248         size = le32_to_cpu(entry->e_value_size);
249         if (buffer) {
250                 error = -ERANGE;
251                 if (size > buffer_size)
252                         goto cleanup;
253                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
254                        size);
255         }
256         error = size;
257
258 cleanup:
259         brelse(bh);
260         return error;
261 }
262
263 static int
264 ext3_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
265                      void *buffer, size_t buffer_size)
266 {
267         struct ext3_xattr_ibody_header *header;
268         struct ext3_xattr_entry *entry;
269         struct ext3_inode *raw_inode;
270         struct ext3_iloc iloc;
271         size_t size;
272         void *end;
273         int error;
274
275         if (!(EXT3_I(inode)->i_state & EXT3_STATE_XATTR))
276                 return -ENODATA;
277         error = ext3_get_inode_loc(inode, &iloc);
278         if (error)
279                 return error;
280         raw_inode = ext3_raw_inode(&iloc);
281         header = IHDR(inode, raw_inode);
282         entry = IFIRST(header);
283         end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
284         error = ext3_xattr_check_names(entry, end);
285         if (error)
286                 goto cleanup;
287         error = ext3_xattr_find_entry(&entry, name_index, name,
288                                       end - (void *)entry, 0);
289         if (error)
290                 goto cleanup;
291         size = le32_to_cpu(entry->e_value_size);
292         if (buffer) {
293                 error = -ERANGE;
294                 if (size > buffer_size)
295                         goto cleanup;
296                 memcpy(buffer, (void *)IFIRST(header) +
297                        le16_to_cpu(entry->e_value_offs), size);
298         }
299         error = size;
300
301 cleanup:
302         brelse(iloc.bh);
303         return error;
304 }
305
306 /*
307  * ext3_xattr_get()
308  *
309  * Copy an extended attribute into the buffer
310  * provided, or compute the buffer size required.
311  * Buffer is NULL to compute the size of the buffer required.
312  *
313  * Returns a negative error number on failure, or the number of bytes
314  * used / required on success.
315  */
316 int
317 ext3_xattr_get(struct inode *inode, int name_index, const char *name,
318                void *buffer, size_t buffer_size)
319 {
320         int error;
321
322         down_read(&EXT3_I(inode)->xattr_sem);
323         error = ext3_xattr_ibody_get(inode, name_index, name, buffer,
324                                      buffer_size);
325         if (error == -ENODATA)
326                 error = ext3_xattr_block_get(inode, name_index, name, buffer,
327                                              buffer_size);
328         up_read(&EXT3_I(inode)->xattr_sem);
329         return error;
330 }
331
332 static int
333 ext3_xattr_list_entries(struct inode *inode, struct ext3_xattr_entry *entry,
334                         char *buffer, size_t buffer_size)
335 {
336         size_t rest = buffer_size;
337
338         for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
339                 struct xattr_handler *handler =
340                         ext3_xattr_handler(entry->e_name_index);
341
342                 if (handler) {
343                         size_t size = handler->list(inode, buffer, rest,
344                                                     entry->e_name,
345                                                     entry->e_name_len);
346                         if (buffer) {
347                                 if (size > rest)
348                                         return -ERANGE;
349                                 buffer += size;
350                         }
351                         rest -= size;
352                 }
353         }
354         return buffer_size - rest;
355 }
356
357 static int
358 ext3_xattr_block_list(struct inode *inode, char *buffer, size_t buffer_size)
359 {
360         struct buffer_head *bh = NULL;
361         int error;
362
363         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
364                   buffer, (long)buffer_size);
365
366         error = 0;
367         if (!EXT3_I(inode)->i_file_acl)
368                 goto cleanup;
369         ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
370         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
371         error = -EIO;
372         if (!bh)
373                 goto cleanup;
374         ea_bdebug(bh, "b_count=%d, refcount=%d",
375                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
376         if (ext3_xattr_check_block(bh)) {
377                 ext3_error(inode->i_sb, __FUNCTION__,
378                            "inode %lu: bad block "E3FSBLK, inode->i_ino,
379                            EXT3_I(inode)->i_file_acl);
380                 error = -EIO;
381                 goto cleanup;
382         }
383         ext3_xattr_cache_insert(bh);
384         error = ext3_xattr_list_entries(inode, BFIRST(bh), buffer, buffer_size);
385
386 cleanup:
387         brelse(bh);
388
389         return error;
390 }
391
392 static int
393 ext3_xattr_ibody_list(struct inode *inode, char *buffer, size_t buffer_size)
394 {
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_I(inode)->i_state & 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(inode, 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 int
431 ext3_xattr_list(struct inode *inode, char *buffer, size_t buffer_size)
432 {
433         int i_error, b_error;
434
435         down_read(&EXT3_I(inode)->xattr_sem);
436         i_error = ext3_xattr_ibody_list(inode, 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(inode, buffer, buffer_size);
445                 if (b_error < 0)
446                         i_error = 0;
447         }
448         up_read(&EXT3_I(inode)->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                 sb->s_dirt = 1;
465                 ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
466         }
467 }
468
469 /*
470  * Release the xattr block BH: If the reference count is > 1, decrement
471  * it; otherwise free the block.
472  */
473 static void
474 ext3_xattr_release_block(handle_t *handle, struct inode *inode,
475                          struct buffer_head *bh)
476 {
477         struct mb_cache_entry *ce = NULL;
478         int error = 0;
479
480         ce = mb_cache_entry_get(ext3_xattr_cache, bh->b_bdev, bh->b_blocknr);
481         error = ext3_journal_get_write_access(handle, bh);
482         if (error)
483                  goto out;
484
485         lock_buffer(bh);
486
487         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
488                 ea_bdebug(bh, "refcount now=0; freeing");
489                 if (ce)
490                         mb_cache_entry_free(ce);
491                 ext3_free_blocks(handle, inode, bh->b_blocknr, 1);
492                 get_bh(bh);
493                 ext3_forget(handle, 1, inode, bh, bh->b_blocknr);
494         } else {
495                 BHDR(bh)->h_refcount = cpu_to_le32(
496                                 le32_to_cpu(BHDR(bh)->h_refcount) - 1);
497                 error = ext3_journal_dirty_metadata(handle, bh);
498                 if (IS_SYNC(inode))
499                         handle->h_sync = 1;
500                 DQUOT_FREE_BLOCK(inode, 1);
501                 ea_bdebug(bh, "refcount now=%d; releasing",
502                           le32_to_cpu(BHDR(bh)->h_refcount));
503                 if (ce)
504                         mb_cache_entry_release(ce);
505         }
506         unlock_buffer(bh);
507 out:
508         ext3_std_error(inode->i_sb, error);
509         return;
510 }
511
512 struct ext3_xattr_info {
513         int name_index;
514         const char *name;
515         const void *value;
516         size_t value_len;
517 };
518
519 struct ext3_xattr_search {
520         struct ext3_xattr_entry *first;
521         void *base;
522         void *end;
523         struct ext3_xattr_entry *here;
524         int not_found;
525 };
526
527 static int
528 ext3_xattr_set_entry(struct ext3_xattr_info *i, struct ext3_xattr_search *s)
529 {
530         struct ext3_xattr_entry *last;
531         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
532
533         /* Compute min_offs and last. */
534         last = s->first;
535         for (; !IS_LAST_ENTRY(last); last = EXT3_XATTR_NEXT(last)) {
536                 if (!last->e_value_block && last->e_value_size) {
537                         size_t offs = le16_to_cpu(last->e_value_offs);
538                         if (offs < min_offs)
539                                 min_offs = offs;
540                 }
541         }
542         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
543         if (!s->not_found) {
544                 if (!s->here->e_value_block && s->here->e_value_size) {
545                         size_t size = le32_to_cpu(s->here->e_value_size);
546                         free += EXT3_XATTR_SIZE(size);
547                 }
548                 free += EXT3_XATTR_LEN(name_len);
549         }
550         if (i->value) {
551                 if (free < EXT3_XATTR_SIZE(i->value_len) ||
552                     free < EXT3_XATTR_LEN(name_len) +
553                            EXT3_XATTR_SIZE(i->value_len))
554                         return -ENOSPC;
555         }
556
557         if (i->value && s->not_found) {
558                 /* Insert the new name. */
559                 size_t size = EXT3_XATTR_LEN(name_len);
560                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
561                 memmove((void *)s->here + size, s->here, rest);
562                 memset(s->here, 0, size);
563                 s->here->e_name_index = i->name_index;
564                 s->here->e_name_len = name_len;
565                 memcpy(s->here->e_name, i->name, name_len);
566         } else {
567                 if (!s->here->e_value_block && s->here->e_value_size) {
568                         void *first_val = s->base + min_offs;
569                         size_t offs = le16_to_cpu(s->here->e_value_offs);
570                         void *val = s->base + offs;
571                         size_t size = EXT3_XATTR_SIZE(
572                                 le32_to_cpu(s->here->e_value_size));
573
574                         if (i->value && size == EXT3_XATTR_SIZE(i->value_len)) {
575                                 /* The old and the new value have the same
576                                    size. Just replace. */
577                                 s->here->e_value_size =
578                                         cpu_to_le32(i->value_len);
579                                 memset(val + size - EXT3_XATTR_PAD, 0,
580                                        EXT3_XATTR_PAD); /* Clear pad bytes. */
581                                 memcpy(val, i->value, i->value_len);
582                                 return 0;
583                         }
584
585                         /* Remove the old value. */
586                         memmove(first_val + size, first_val, val - first_val);
587                         memset(first_val, 0, size);
588                         s->here->e_value_size = 0;
589                         s->here->e_value_offs = 0;
590                         min_offs += size;
591
592                         /* Adjust all value offsets. */
593                         last = s->first;
594                         while (!IS_LAST_ENTRY(last)) {
595                                 size_t o = le16_to_cpu(last->e_value_offs);
596                                 if (!last->e_value_block &&
597                                     last->e_value_size && o < offs)
598                                         last->e_value_offs =
599                                                 cpu_to_le16(o + size);
600                                 last = EXT3_XATTR_NEXT(last);
601                         }
602                 }
603                 if (!i->value) {
604                         /* Remove the old name. */
605                         size_t size = EXT3_XATTR_LEN(name_len);
606                         last = ENTRY((void *)last - size);
607                         memmove(s->here, (void *)s->here + size,
608                                 (void *)last - (void *)s->here + sizeof(__u32));
609                         memset(last, 0, size);
610                 }
611         }
612
613         if (i->value) {
614                 /* Insert the new value. */
615                 s->here->e_value_size = cpu_to_le32(i->value_len);
616                 if (i->value_len) {
617                         size_t size = EXT3_XATTR_SIZE(i->value_len);
618                         void *val = s->base + min_offs - size;
619                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
620                         memset(val + size - EXT3_XATTR_PAD, 0,
621                                EXT3_XATTR_PAD); /* Clear the pad bytes. */
622                         memcpy(val, i->value, i->value_len);
623                 }
624         }
625         return 0;
626 }
627
628 struct ext3_xattr_block_find {
629         struct ext3_xattr_search s;
630         struct buffer_head *bh;
631 };
632
633 static int
634 ext3_xattr_block_find(struct inode *inode, struct ext3_xattr_info *i,
635                       struct ext3_xattr_block_find *bs)
636 {
637         struct super_block *sb = inode->i_sb;
638         int error;
639
640         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
641                   i->name_index, i->name, i->value, (long)i->value_len);
642
643         if (EXT3_I(inode)->i_file_acl) {
644                 /* The inode already has an extended attribute block. */
645                 bs->bh = sb_bread(sb, EXT3_I(inode)->i_file_acl);
646                 error = -EIO;
647                 if (!bs->bh)
648                         goto cleanup;
649                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
650                         atomic_read(&(bs->bh->b_count)),
651                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
652                 if (ext3_xattr_check_block(bs->bh)) {
653                         ext3_error(sb, __FUNCTION__,
654                                 "inode %lu: bad block "E3FSBLK, inode->i_ino,
655                                 EXT3_I(inode)->i_file_acl);
656                         error = -EIO;
657                         goto cleanup;
658                 }
659                 /* Find the named attribute. */
660                 bs->s.base = BHDR(bs->bh);
661                 bs->s.first = BFIRST(bs->bh);
662                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
663                 bs->s.here = bs->s.first;
664                 error = ext3_xattr_find_entry(&bs->s.here, i->name_index,
665                                               i->name, bs->bh->b_size, 1);
666                 if (error && error != -ENODATA)
667                         goto cleanup;
668                 bs->s.not_found = error;
669         }
670         error = 0;
671
672 cleanup:
673         return error;
674 }
675
676 static int
677 ext3_xattr_block_set(handle_t *handle, struct inode *inode,
678                      struct ext3_xattr_info *i,
679                      struct ext3_xattr_block_find *bs)
680 {
681         struct super_block *sb = inode->i_sb;
682         struct buffer_head *new_bh = NULL;
683         struct ext3_xattr_search *s = &bs->s;
684         struct mb_cache_entry *ce = NULL;
685         int error = 0;
686
687 #define header(x) ((struct ext3_xattr_header *)(x))
688
689         if (i->value && i->value_len > sb->s_blocksize)
690                 return -ENOSPC;
691         if (s->base) {
692                 ce = mb_cache_entry_get(ext3_xattr_cache, bs->bh->b_bdev,
693                                         bs->bh->b_blocknr);
694                 error = ext3_journal_get_write_access(handle, bs->bh);
695                 if (error)
696                         goto cleanup;
697                 lock_buffer(bs->bh);
698
699                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
700                         if (ce) {
701                                 mb_cache_entry_free(ce);
702                                 ce = NULL;
703                         }
704                         ea_bdebug(bs->bh, "modifying in-place");
705                         error = ext3_xattr_set_entry(i, s);
706                         if (!error) {
707                                 if (!IS_LAST_ENTRY(s->first))
708                                         ext3_xattr_rehash(header(s->base),
709                                                           s->here);
710                                 ext3_xattr_cache_insert(bs->bh);
711                         }
712                         unlock_buffer(bs->bh);
713                         if (error == -EIO)
714                                 goto bad_block;
715                         if (!error)
716                                 error = ext3_journal_dirty_metadata(handle,
717                                                                     bs->bh);
718                         if (error)
719                                 goto cleanup;
720                         goto inserted;
721                 } else {
722                         int offset = (char *)s->here - bs->bh->b_data;
723
724                         unlock_buffer(bs->bh);
725                         journal_release_buffer(handle, bs->bh);
726
727                         if (ce) {
728                                 mb_cache_entry_release(ce);
729                                 ce = NULL;
730                         }
731                         ea_bdebug(bs->bh, "cloning");
732                         s->base = kmalloc(bs->bh->b_size, GFP_KERNEL);
733                         error = -ENOMEM;
734                         if (s->base == NULL)
735                                 goto cleanup;
736                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
737                         s->first = ENTRY(header(s->base)+1);
738                         header(s->base)->h_refcount = cpu_to_le32(1);
739                         s->here = ENTRY(s->base + offset);
740                         s->end = s->base + bs->bh->b_size;
741                 }
742         } else {
743                 /* Allocate a buffer where we construct the new block. */
744                 s->base = kmalloc(sb->s_blocksize, GFP_KERNEL);
745                 /* assert(header == s->base) */
746                 error = -ENOMEM;
747                 if (s->base == NULL)
748                         goto cleanup;
749                 memset(s->base, 0, sb->s_blocksize);
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 (DQUOT_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                                 BHDR(new_bh)->h_refcount = cpu_to_le32(1 +
785                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
786                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
787                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
788                                 unlock_buffer(new_bh);
789                                 error = ext3_journal_dirty_metadata(handle,
790                                                                     new_bh);
791                                 if (error)
792                                         goto cleanup_dquot;
793                         }
794                         mb_cache_entry_release(ce);
795                         ce = NULL;
796                 } else if (bs->bh && s->base == bs->bh->b_data) {
797                         /* We were modifying this block in-place. */
798                         ea_bdebug(bs->bh, "keeping this block");
799                         new_bh = bs->bh;
800                         get_bh(new_bh);
801                 } else {
802                         /* We need to allocate a new block */
803                         ext3_fsblk_t goal = le32_to_cpu(
804                                         EXT3_SB(sb)->s_es->s_first_data_block) +
805                                 (ext3_fsblk_t)EXT3_I(inode)->i_block_group *
806                                 EXT3_BLOCKS_PER_GROUP(sb);
807                         ext3_fsblk_t block = ext3_new_block(handle, inode,
808                                                         goal, &error);
809                         if (error)
810                                 goto cleanup;
811                         ea_idebug(inode, "creating block %d", block);
812
813                         new_bh = sb_getblk(sb, block);
814                         if (!new_bh) {
815 getblk_failed:
816                                 ext3_free_blocks(handle, inode, block, 1);
817                                 error = -EIO;
818                                 goto cleanup;
819                         }
820                         lock_buffer(new_bh);
821                         error = ext3_journal_get_create_access(handle, new_bh);
822                         if (error) {
823                                 unlock_buffer(new_bh);
824                                 goto getblk_failed;
825                         }
826                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
827                         set_buffer_uptodate(new_bh);
828                         unlock_buffer(new_bh);
829                         ext3_xattr_cache_insert(new_bh);
830                         error = ext3_journal_dirty_metadata(handle, new_bh);
831                         if (error)
832                                 goto cleanup;
833                 }
834         }
835
836         /* Update the inode. */
837         EXT3_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
838
839         /* Drop the previous xattr block. */
840         if (bs->bh && bs->bh != new_bh)
841                 ext3_xattr_release_block(handle, inode, bs->bh);
842         error = 0;
843
844 cleanup:
845         if (ce)
846                 mb_cache_entry_release(ce);
847         brelse(new_bh);
848         if (!(bs->bh && s->base == bs->bh->b_data))
849                 kfree(s->base);
850
851         return error;
852
853 cleanup_dquot:
854         DQUOT_FREE_BLOCK(inode, 1);
855         goto cleanup;
856
857 bad_block:
858         ext3_error(inode->i_sb, __FUNCTION__,
859                    "inode %lu: bad block "E3FSBLK, inode->i_ino,
860                    EXT3_I(inode)->i_file_acl);
861         goto cleanup;
862
863 #undef header
864 }
865
866 struct ext3_xattr_ibody_find {
867         struct ext3_xattr_search s;
868         struct ext3_iloc iloc;
869 };
870
871 static int
872 ext3_xattr_ibody_find(struct inode *inode, struct ext3_xattr_info *i,
873                       struct ext3_xattr_ibody_find *is)
874 {
875         struct ext3_xattr_ibody_header *header;
876         struct ext3_inode *raw_inode;
877         int error;
878
879         if (EXT3_I(inode)->i_extra_isize == 0)
880                 return 0;
881         raw_inode = ext3_raw_inode(&is->iloc);
882         header = IHDR(inode, raw_inode);
883         is->s.base = is->s.first = IFIRST(header);
884         is->s.here = is->s.first;
885         is->s.end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
886         if (EXT3_I(inode)->i_state & EXT3_STATE_XATTR) {
887                 error = ext3_xattr_check_names(IFIRST(header), is->s.end);
888                 if (error)
889                         return error;
890                 /* Find the named attribute. */
891                 error = ext3_xattr_find_entry(&is->s.here, i->name_index,
892                                               i->name, is->s.end -
893                                               (void *)is->s.base, 0);
894                 if (error && error != -ENODATA)
895                         return error;
896                 is->s.not_found = error;
897         }
898         return 0;
899 }
900
901 static int
902 ext3_xattr_ibody_set(handle_t *handle, struct inode *inode,
903                      struct ext3_xattr_info *i,
904                      struct ext3_xattr_ibody_find *is)
905 {
906         struct ext3_xattr_ibody_header *header;
907         struct ext3_xattr_search *s = &is->s;
908         int error;
909
910         if (EXT3_I(inode)->i_extra_isize == 0)
911                 return -ENOSPC;
912         error = ext3_xattr_set_entry(i, s);
913         if (error)
914                 return error;
915         header = IHDR(inode, ext3_raw_inode(&is->iloc));
916         if (!IS_LAST_ENTRY(s->first)) {
917                 header->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
918                 EXT3_I(inode)->i_state |= EXT3_STATE_XATTR;
919         } else {
920                 header->h_magic = cpu_to_le32(0);
921                 EXT3_I(inode)->i_state &= ~EXT3_STATE_XATTR;
922         }
923         return 0;
924 }
925
926 /*
927  * ext3_xattr_set_handle()
928  *
929  * Create, replace or remove an extended attribute for this inode. Buffer
930  * is NULL to remove an existing extended attribute, and non-NULL to
931  * either replace an existing extended attribute, or create a new extended
932  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
933  * specify that an extended attribute must exist and must not exist
934  * previous to the call, respectively.
935  *
936  * Returns 0, or a negative error number on failure.
937  */
938 int
939 ext3_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
940                       const char *name, const void *value, size_t value_len,
941                       int flags)
942 {
943         struct ext3_xattr_info i = {
944                 .name_index = name_index,
945                 .name = name,
946                 .value = value,
947                 .value_len = value_len,
948
949         };
950         struct ext3_xattr_ibody_find is = {
951                 .s = { .not_found = -ENODATA, },
952         };
953         struct ext3_xattr_block_find bs = {
954                 .s = { .not_found = -ENODATA, },
955         };
956         int error;
957
958         if (!name)
959                 return -EINVAL;
960         if (strlen(name) > 255)
961                 return -ERANGE;
962         down_write(&EXT3_I(inode)->xattr_sem);
963         error = ext3_get_inode_loc(inode, &is.iloc);
964         if (error)
965                 goto cleanup;
966
967         if (EXT3_I(inode)->i_state & EXT3_STATE_NEW) {
968                 struct ext3_inode *raw_inode = ext3_raw_inode(&is.iloc);
969                 memset(raw_inode, 0, EXT3_SB(inode->i_sb)->s_inode_size);
970                 EXT3_I(inode)->i_state &= ~EXT3_STATE_NEW;
971         }
972
973         error = ext3_xattr_ibody_find(inode, &i, &is);
974         if (error)
975                 goto cleanup;
976         if (is.s.not_found)
977                 error = ext3_xattr_block_find(inode, &i, &bs);
978         if (error)
979                 goto cleanup;
980         if (is.s.not_found && bs.s.not_found) {
981                 error = -ENODATA;
982                 if (flags & XATTR_REPLACE)
983                         goto cleanup;
984                 error = 0;
985                 if (!value)
986                         goto cleanup;
987         } else {
988                 error = -EEXIST;
989                 if (flags & XATTR_CREATE)
990                         goto cleanup;
991         }
992         error = ext3_journal_get_write_access(handle, is.iloc.bh);
993         if (error)
994                 goto cleanup;
995         if (!value) {
996                 if (!is.s.not_found)
997                         error = ext3_xattr_ibody_set(handle, inode, &i, &is);
998                 else if (!bs.s.not_found)
999                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1000         } else {
1001                 error = ext3_xattr_ibody_set(handle, inode, &i, &is);
1002                 if (!error && !bs.s.not_found) {
1003                         i.value = NULL;
1004                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1005                 } else if (error == -ENOSPC) {
1006                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1007                         if (error)
1008                                 goto cleanup;
1009                         if (!is.s.not_found) {
1010                                 i.value = NULL;
1011                                 error = ext3_xattr_ibody_set(handle, inode, &i,
1012                                                              &is);
1013                         }
1014                 }
1015         }
1016         if (!error) {
1017                 ext3_xattr_update_super_block(handle, inode->i_sb);
1018                 inode->i_ctime = CURRENT_TIME_SEC;
1019                 error = ext3_mark_iloc_dirty(handle, inode, &is.iloc);
1020                 /*
1021                  * The bh is consumed by ext3_mark_iloc_dirty, even with
1022                  * error != 0.
1023                  */
1024                 is.iloc.bh = NULL;
1025                 if (IS_SYNC(inode))
1026                         handle->h_sync = 1;
1027         }
1028
1029 cleanup:
1030         brelse(is.iloc.bh);
1031         brelse(bs.bh);
1032         up_write(&EXT3_I(inode)->xattr_sem);
1033         return error;
1034 }
1035
1036 /*
1037  * ext3_xattr_set()
1038  *
1039  * Like ext3_xattr_set_handle, but start from an inode. This extended
1040  * attribute modification is a filesystem transaction by itself.
1041  *
1042  * Returns 0, or a negative error number on failure.
1043  */
1044 int
1045 ext3_xattr_set(struct inode *inode, int name_index, const char *name,
1046                const void *value, size_t value_len, int flags)
1047 {
1048         handle_t *handle;
1049         int error, retries = 0;
1050
1051 retry:
1052         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
1053         if (IS_ERR(handle)) {
1054                 error = PTR_ERR(handle);
1055         } else {
1056                 int error2;
1057
1058                 error = ext3_xattr_set_handle(handle, inode, name_index, name,
1059                                               value, value_len, flags);
1060                 error2 = ext3_journal_stop(handle);
1061                 if (error == -ENOSPC &&
1062                     ext3_should_retry_alloc(inode->i_sb, &retries))
1063                         goto retry;
1064                 if (error == 0)
1065                         error = error2;
1066         }
1067
1068         return error;
1069 }
1070
1071 /*
1072  * ext3_xattr_delete_inode()
1073  *
1074  * Free extended attribute resources associated with this inode. This
1075  * is called immediately before an inode is freed. We have exclusive
1076  * access to the inode.
1077  */
1078 void
1079 ext3_xattr_delete_inode(handle_t *handle, struct inode *inode)
1080 {
1081         struct buffer_head *bh = NULL;
1082
1083         if (!EXT3_I(inode)->i_file_acl)
1084                 goto cleanup;
1085         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
1086         if (!bh) {
1087                 ext3_error(inode->i_sb, __FUNCTION__,
1088                         "inode %lu: block "E3FSBLK" read error", inode->i_ino,
1089                         EXT3_I(inode)->i_file_acl);
1090                 goto cleanup;
1091         }
1092         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
1093             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1094                 ext3_error(inode->i_sb, __FUNCTION__,
1095                         "inode %lu: bad block "E3FSBLK, inode->i_ino,
1096                         EXT3_I(inode)->i_file_acl);
1097                 goto cleanup;
1098         }
1099         ext3_xattr_release_block(handle, inode, bh);
1100         EXT3_I(inode)->i_file_acl = 0;
1101
1102 cleanup:
1103         brelse(bh);
1104 }
1105
1106 /*
1107  * ext3_xattr_put_super()
1108  *
1109  * This is called when a file system is unmounted.
1110  */
1111 void
1112 ext3_xattr_put_super(struct super_block *sb)
1113 {
1114         mb_cache_shrink(sb->s_bdev);
1115 }
1116
1117 /*
1118  * ext3_xattr_cache_insert()
1119  *
1120  * Create a new entry in the extended attribute cache, and insert
1121  * it unless such an entry is already in the cache.
1122  *
1123  * Returns 0, or a negative error number on failure.
1124  */
1125 static void
1126 ext3_xattr_cache_insert(struct buffer_head *bh)
1127 {
1128         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1129         struct mb_cache_entry *ce;
1130         int error;
1131
1132         ce = mb_cache_entry_alloc(ext3_xattr_cache);
1133         if (!ce) {
1134                 ea_bdebug(bh, "out of memory");
1135                 return;
1136         }
1137         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
1138         if (error) {
1139                 mb_cache_entry_free(ce);
1140                 if (error == -EBUSY) {
1141                         ea_bdebug(bh, "already in cache");
1142                         error = 0;
1143                 }
1144         } else {
1145                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1146                 mb_cache_entry_release(ce);
1147         }
1148 }
1149
1150 /*
1151  * ext3_xattr_cmp()
1152  *
1153  * Compare two extended attribute blocks for equality.
1154  *
1155  * Returns 0 if the blocks are equal, 1 if they differ, and
1156  * a negative error number on errors.
1157  */
1158 static int
1159 ext3_xattr_cmp(struct ext3_xattr_header *header1,
1160                struct ext3_xattr_header *header2)
1161 {
1162         struct ext3_xattr_entry *entry1, *entry2;
1163
1164         entry1 = ENTRY(header1+1);
1165         entry2 = ENTRY(header2+1);
1166         while (!IS_LAST_ENTRY(entry1)) {
1167                 if (IS_LAST_ENTRY(entry2))
1168                         return 1;
1169                 if (entry1->e_hash != entry2->e_hash ||
1170                     entry1->e_name_index != entry2->e_name_index ||
1171                     entry1->e_name_len != entry2->e_name_len ||
1172                     entry1->e_value_size != entry2->e_value_size ||
1173                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1174                         return 1;
1175                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1176                         return -EIO;
1177                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1178                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1179                            le32_to_cpu(entry1->e_value_size)))
1180                         return 1;
1181
1182                 entry1 = EXT3_XATTR_NEXT(entry1);
1183                 entry2 = EXT3_XATTR_NEXT(entry2);
1184         }
1185         if (!IS_LAST_ENTRY(entry2))
1186                 return 1;
1187         return 0;
1188 }
1189
1190 /*
1191  * ext3_xattr_cache_find()
1192  *
1193  * Find an identical extended attribute block.
1194  *
1195  * Returns a pointer to the block found, or NULL if such a block was
1196  * not found or an error occurred.
1197  */
1198 static struct buffer_head *
1199 ext3_xattr_cache_find(struct inode *inode, struct ext3_xattr_header *header,
1200                       struct mb_cache_entry **pce)
1201 {
1202         __u32 hash = le32_to_cpu(header->h_hash);
1203         struct mb_cache_entry *ce;
1204
1205         if (!header->h_hash)
1206                 return NULL;  /* never share */
1207         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1208 again:
1209         ce = mb_cache_entry_find_first(ext3_xattr_cache, 0,
1210                                        inode->i_sb->s_bdev, hash);
1211         while (ce) {
1212                 struct buffer_head *bh;
1213
1214                 if (IS_ERR(ce)) {
1215                         if (PTR_ERR(ce) == -EAGAIN)
1216                                 goto again;
1217                         break;
1218                 }
1219                 bh = sb_bread(inode->i_sb, ce->e_block);
1220                 if (!bh) {
1221                         ext3_error(inode->i_sb, __FUNCTION__,
1222                                 "inode %lu: block %lu read error",
1223                                 inode->i_ino, (unsigned long) ce->e_block);
1224                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1225                                 EXT3_XATTR_REFCOUNT_MAX) {
1226                         ea_idebug(inode, "block %lu refcount %d>=%d",
1227                                   (unsigned long) ce->e_block,
1228                                   le32_to_cpu(BHDR(bh)->h_refcount),
1229                                           EXT3_XATTR_REFCOUNT_MAX);
1230                 } else if (ext3_xattr_cmp(header, BHDR(bh)) == 0) {
1231                         *pce = ce;
1232                         return bh;
1233                 }
1234                 brelse(bh);
1235                 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
1236         }
1237         return NULL;
1238 }
1239
1240 #define NAME_HASH_SHIFT 5
1241 #define VALUE_HASH_SHIFT 16
1242
1243 /*
1244  * ext3_xattr_hash_entry()
1245  *
1246  * Compute the hash of an extended attribute.
1247  */
1248 static inline void ext3_xattr_hash_entry(struct ext3_xattr_header *header,
1249                                          struct ext3_xattr_entry *entry)
1250 {
1251         __u32 hash = 0;
1252         char *name = entry->e_name;
1253         int n;
1254
1255         for (n=0; n < entry->e_name_len; n++) {
1256                 hash = (hash << NAME_HASH_SHIFT) ^
1257                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1258                        *name++;
1259         }
1260
1261         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1262                 __le32 *value = (__le32 *)((char *)header +
1263                         le16_to_cpu(entry->e_value_offs));
1264                 for (n = (le32_to_cpu(entry->e_value_size) +
1265                      EXT3_XATTR_ROUND) >> EXT3_XATTR_PAD_BITS; n; n--) {
1266                         hash = (hash << VALUE_HASH_SHIFT) ^
1267                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1268                                le32_to_cpu(*value++);
1269                 }
1270         }
1271         entry->e_hash = cpu_to_le32(hash);
1272 }
1273
1274 #undef NAME_HASH_SHIFT
1275 #undef VALUE_HASH_SHIFT
1276
1277 #define BLOCK_HASH_SHIFT 16
1278
1279 /*
1280  * ext3_xattr_rehash()
1281  *
1282  * Re-compute the extended attribute hash value after an entry has changed.
1283  */
1284 static void ext3_xattr_rehash(struct ext3_xattr_header *header,
1285                               struct ext3_xattr_entry *entry)
1286 {
1287         struct ext3_xattr_entry *here;
1288         __u32 hash = 0;
1289
1290         ext3_xattr_hash_entry(header, entry);
1291         here = ENTRY(header+1);
1292         while (!IS_LAST_ENTRY(here)) {
1293                 if (!here->e_hash) {
1294                         /* Block is not shared if an entry's hash value == 0 */
1295                         hash = 0;
1296                         break;
1297                 }
1298                 hash = (hash << BLOCK_HASH_SHIFT) ^
1299                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1300                        le32_to_cpu(here->e_hash);
1301                 here = EXT3_XATTR_NEXT(here);
1302         }
1303         header->h_hash = cpu_to_le32(hash);
1304 }
1305
1306 #undef BLOCK_HASH_SHIFT
1307
1308 int __init
1309 init_ext3_xattr(void)
1310 {
1311         ext3_xattr_cache = mb_cache_create("ext3_xattr", NULL,
1312                 sizeof(struct mb_cache_entry) +
1313                 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1314         if (!ext3_xattr_cache)
1315                 return -ENOMEM;
1316         return 0;
1317 }
1318
1319 void
1320 exit_ext3_xattr(void)
1321 {
1322         if (ext3_xattr_cache)
1323                 mb_cache_destroy(ext3_xattr_cache);
1324         ext3_xattr_cache = NULL;
1325 }