vfs: fix possible deadlock in ext2, ext3, ext4 when using xattrs
[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
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                 le32_add_cpu(&BHDR(bh)->h_refcount, -1);
496                 error = ext3_journal_dirty_metadata(handle, bh);
497                 if (IS_SYNC(inode))
498                         handle->h_sync = 1;
499                 DQUOT_FREE_BLOCK(inode, 1);
500                 ea_bdebug(bh, "refcount now=%d; releasing",
501                           le32_to_cpu(BHDR(bh)->h_refcount));
502                 if (ce)
503                         mb_cache_entry_release(ce);
504         }
505         unlock_buffer(bh);
506 out:
507         ext3_std_error(inode->i_sb, error);
508         return;
509 }
510
511 struct ext3_xattr_info {
512         int name_index;
513         const char *name;
514         const void *value;
515         size_t value_len;
516 };
517
518 struct ext3_xattr_search {
519         struct ext3_xattr_entry *first;
520         void *base;
521         void *end;
522         struct ext3_xattr_entry *here;
523         int not_found;
524 };
525
526 static int
527 ext3_xattr_set_entry(struct ext3_xattr_info *i, struct ext3_xattr_search *s)
528 {
529         struct ext3_xattr_entry *last;
530         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
531
532         /* Compute min_offs and last. */
533         last = s->first;
534         for (; !IS_LAST_ENTRY(last); last = EXT3_XATTR_NEXT(last)) {
535                 if (!last->e_value_block && last->e_value_size) {
536                         size_t offs = le16_to_cpu(last->e_value_offs);
537                         if (offs < min_offs)
538                                 min_offs = offs;
539                 }
540         }
541         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
542         if (!s->not_found) {
543                 if (!s->here->e_value_block && s->here->e_value_size) {
544                         size_t size = le32_to_cpu(s->here->e_value_size);
545                         free += EXT3_XATTR_SIZE(size);
546                 }
547                 free += EXT3_XATTR_LEN(name_len);
548         }
549         if (i->value) {
550                 if (free < EXT3_XATTR_SIZE(i->value_len) ||
551                     free < EXT3_XATTR_LEN(name_len) +
552                            EXT3_XATTR_SIZE(i->value_len))
553                         return -ENOSPC;
554         }
555
556         if (i->value && s->not_found) {
557                 /* Insert the new name. */
558                 size_t size = EXT3_XATTR_LEN(name_len);
559                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
560                 memmove((void *)s->here + size, s->here, rest);
561                 memset(s->here, 0, size);
562                 s->here->e_name_index = i->name_index;
563                 s->here->e_name_len = name_len;
564                 memcpy(s->here->e_name, i->name, name_len);
565         } else {
566                 if (!s->here->e_value_block && s->here->e_value_size) {
567                         void *first_val = s->base + min_offs;
568                         size_t offs = le16_to_cpu(s->here->e_value_offs);
569                         void *val = s->base + offs;
570                         size_t size = EXT3_XATTR_SIZE(
571                                 le32_to_cpu(s->here->e_value_size));
572
573                         if (i->value && size == EXT3_XATTR_SIZE(i->value_len)) {
574                                 /* The old and the new value have the same
575                                    size. Just replace. */
576                                 s->here->e_value_size =
577                                         cpu_to_le32(i->value_len);
578                                 memset(val + size - EXT3_XATTR_PAD, 0,
579                                        EXT3_XATTR_PAD); /* Clear pad bytes. */
580                                 memcpy(val, i->value, i->value_len);
581                                 return 0;
582                         }
583
584                         /* Remove the old value. */
585                         memmove(first_val + size, first_val, val - first_val);
586                         memset(first_val, 0, size);
587                         s->here->e_value_size = 0;
588                         s->here->e_value_offs = 0;
589                         min_offs += size;
590
591                         /* Adjust all value offsets. */
592                         last = s->first;
593                         while (!IS_LAST_ENTRY(last)) {
594                                 size_t o = le16_to_cpu(last->e_value_offs);
595                                 if (!last->e_value_block &&
596                                     last->e_value_size && o < offs)
597                                         last->e_value_offs =
598                                                 cpu_to_le16(o + size);
599                                 last = EXT3_XATTR_NEXT(last);
600                         }
601                 }
602                 if (!i->value) {
603                         /* Remove the old name. */
604                         size_t size = EXT3_XATTR_LEN(name_len);
605                         last = ENTRY((void *)last - size);
606                         memmove(s->here, (void *)s->here + size,
607                                 (void *)last - (void *)s->here + sizeof(__u32));
608                         memset(last, 0, size);
609                 }
610         }
611
612         if (i->value) {
613                 /* Insert the new value. */
614                 s->here->e_value_size = cpu_to_le32(i->value_len);
615                 if (i->value_len) {
616                         size_t size = EXT3_XATTR_SIZE(i->value_len);
617                         void *val = s->base + min_offs - size;
618                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
619                         memset(val + size - EXT3_XATTR_PAD, 0,
620                                EXT3_XATTR_PAD); /* Clear the pad bytes. */
621                         memcpy(val, i->value, i->value_len);
622                 }
623         }
624         return 0;
625 }
626
627 struct ext3_xattr_block_find {
628         struct ext3_xattr_search s;
629         struct buffer_head *bh;
630 };
631
632 static int
633 ext3_xattr_block_find(struct inode *inode, struct ext3_xattr_info *i,
634                       struct ext3_xattr_block_find *bs)
635 {
636         struct super_block *sb = inode->i_sb;
637         int error;
638
639         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
640                   i->name_index, i->name, i->value, (long)i->value_len);
641
642         if (EXT3_I(inode)->i_file_acl) {
643                 /* The inode already has an extended attribute block. */
644                 bs->bh = sb_bread(sb, EXT3_I(inode)->i_file_acl);
645                 error = -EIO;
646                 if (!bs->bh)
647                         goto cleanup;
648                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
649                         atomic_read(&(bs->bh->b_count)),
650                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
651                 if (ext3_xattr_check_block(bs->bh)) {
652                         ext3_error(sb, __FUNCTION__,
653                                 "inode %lu: bad block "E3FSBLK, inode->i_ino,
654                                 EXT3_I(inode)->i_file_acl);
655                         error = -EIO;
656                         goto cleanup;
657                 }
658                 /* Find the named attribute. */
659                 bs->s.base = BHDR(bs->bh);
660                 bs->s.first = BFIRST(bs->bh);
661                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
662                 bs->s.here = bs->s.first;
663                 error = ext3_xattr_find_entry(&bs->s.here, i->name_index,
664                                               i->name, bs->bh->b_size, 1);
665                 if (error && error != -ENODATA)
666                         goto cleanup;
667                 bs->s.not_found = error;
668         }
669         error = 0;
670
671 cleanup:
672         return error;
673 }
674
675 static int
676 ext3_xattr_block_set(handle_t *handle, struct inode *inode,
677                      struct ext3_xattr_info *i,
678                      struct ext3_xattr_block_find *bs)
679 {
680         struct super_block *sb = inode->i_sb;
681         struct buffer_head *new_bh = NULL;
682         struct ext3_xattr_search *s = &bs->s;
683         struct mb_cache_entry *ce = NULL;
684         int error = 0;
685
686 #define header(x) ((struct ext3_xattr_header *)(x))
687
688         if (i->value && i->value_len > sb->s_blocksize)
689                 return -ENOSPC;
690         if (s->base) {
691                 ce = mb_cache_entry_get(ext3_xattr_cache, bs->bh->b_bdev,
692                                         bs->bh->b_blocknr);
693                 error = ext3_journal_get_write_access(handle, bs->bh);
694                 if (error)
695                         goto cleanup;
696                 lock_buffer(bs->bh);
697
698                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
699                         if (ce) {
700                                 mb_cache_entry_free(ce);
701                                 ce = NULL;
702                         }
703                         ea_bdebug(bs->bh, "modifying in-place");
704                         error = ext3_xattr_set_entry(i, s);
705                         if (!error) {
706                                 if (!IS_LAST_ENTRY(s->first))
707                                         ext3_xattr_rehash(header(s->base),
708                                                           s->here);
709                                 ext3_xattr_cache_insert(bs->bh);
710                         }
711                         unlock_buffer(bs->bh);
712                         if (error == -EIO)
713                                 goto bad_block;
714                         if (!error)
715                                 error = ext3_journal_dirty_metadata(handle,
716                                                                     bs->bh);
717                         if (error)
718                                 goto cleanup;
719                         goto inserted;
720                 } else {
721                         int offset = (char *)s->here - bs->bh->b_data;
722
723                         unlock_buffer(bs->bh);
724                         journal_release_buffer(handle, bs->bh);
725
726                         if (ce) {
727                                 mb_cache_entry_release(ce);
728                                 ce = NULL;
729                         }
730                         ea_bdebug(bs->bh, "cloning");
731                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
732                         error = -ENOMEM;
733                         if (s->base == NULL)
734                                 goto cleanup;
735                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
736                         s->first = ENTRY(header(s->base)+1);
737                         header(s->base)->h_refcount = cpu_to_le32(1);
738                         s->here = ENTRY(s->base + offset);
739                         s->end = s->base + bs->bh->b_size;
740                 }
741         } else {
742                 /* Allocate a buffer where we construct the new block. */
743                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
744                 /* assert(header == s->base) */
745                 error = -ENOMEM;
746                 if (s->base == NULL)
747                         goto cleanup;
748                 header(s->base)->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
749                 header(s->base)->h_blocks = cpu_to_le32(1);
750                 header(s->base)->h_refcount = cpu_to_le32(1);
751                 s->first = ENTRY(header(s->base)+1);
752                 s->here = ENTRY(header(s->base)+1);
753                 s->end = s->base + sb->s_blocksize;
754         }
755
756         error = ext3_xattr_set_entry(i, s);
757         if (error == -EIO)
758                 goto bad_block;
759         if (error)
760                 goto cleanup;
761         if (!IS_LAST_ENTRY(s->first))
762                 ext3_xattr_rehash(header(s->base), s->here);
763
764 inserted:
765         if (!IS_LAST_ENTRY(s->first)) {
766                 new_bh = ext3_xattr_cache_find(inode, header(s->base), &ce);
767                 if (new_bh) {
768                         /* We found an identical block in the cache. */
769                         if (new_bh == bs->bh)
770                                 ea_bdebug(new_bh, "keeping");
771                         else {
772                                 /* The old block is released after updating
773                                    the inode. */
774                                 error = -EDQUOT;
775                                 if (DQUOT_ALLOC_BLOCK(inode, 1))
776                                         goto cleanup;
777                                 error = ext3_journal_get_write_access(handle,
778                                                                       new_bh);
779                                 if (error)
780                                         goto cleanup_dquot;
781                                 lock_buffer(new_bh);
782                                 le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
783                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
784                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
785                                 unlock_buffer(new_bh);
786                                 error = ext3_journal_dirty_metadata(handle,
787                                                                     new_bh);
788                                 if (error)
789                                         goto cleanup_dquot;
790                         }
791                         mb_cache_entry_release(ce);
792                         ce = NULL;
793                 } else if (bs->bh && s->base == bs->bh->b_data) {
794                         /* We were modifying this block in-place. */
795                         ea_bdebug(bs->bh, "keeping this block");
796                         new_bh = bs->bh;
797                         get_bh(new_bh);
798                 } else {
799                         /* We need to allocate a new block */
800                         ext3_fsblk_t goal = le32_to_cpu(
801                                         EXT3_SB(sb)->s_es->s_first_data_block) +
802                                 (ext3_fsblk_t)EXT3_I(inode)->i_block_group *
803                                 EXT3_BLOCKS_PER_GROUP(sb);
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         DQUOT_FREE_BLOCK(inode, 1);
852         goto cleanup;
853
854 bad_block:
855         ext3_error(inode->i_sb, __FUNCTION__,
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                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1004                         if (error)
1005                                 goto cleanup;
1006                         if (!is.s.not_found) {
1007                                 i.value = NULL;
1008                                 error = ext3_xattr_ibody_set(handle, inode, &i,
1009                                                              &is);
1010                         }
1011                 }
1012         }
1013         if (!error) {
1014                 ext3_xattr_update_super_block(handle, inode->i_sb);
1015                 inode->i_ctime = CURRENT_TIME_SEC;
1016                 error = ext3_mark_iloc_dirty(handle, inode, &is.iloc);
1017                 /*
1018                  * The bh is consumed by ext3_mark_iloc_dirty, even with
1019                  * error != 0.
1020                  */
1021                 is.iloc.bh = NULL;
1022                 if (IS_SYNC(inode))
1023                         handle->h_sync = 1;
1024         }
1025
1026 cleanup:
1027         brelse(is.iloc.bh);
1028         brelse(bs.bh);
1029         up_write(&EXT3_I(inode)->xattr_sem);
1030         return error;
1031 }
1032
1033 /*
1034  * ext3_xattr_set()
1035  *
1036  * Like ext3_xattr_set_handle, but start from an inode. This extended
1037  * attribute modification is a filesystem transaction by itself.
1038  *
1039  * Returns 0, or a negative error number on failure.
1040  */
1041 int
1042 ext3_xattr_set(struct inode *inode, int name_index, const char *name,
1043                const void *value, size_t value_len, int flags)
1044 {
1045         handle_t *handle;
1046         int error, retries = 0;
1047
1048 retry:
1049         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
1050         if (IS_ERR(handle)) {
1051                 error = PTR_ERR(handle);
1052         } else {
1053                 int error2;
1054
1055                 error = ext3_xattr_set_handle(handle, inode, name_index, name,
1056                                               value, value_len, flags);
1057                 error2 = ext3_journal_stop(handle);
1058                 if (error == -ENOSPC &&
1059                     ext3_should_retry_alloc(inode->i_sb, &retries))
1060                         goto retry;
1061                 if (error == 0)
1062                         error = error2;
1063         }
1064
1065         return error;
1066 }
1067
1068 /*
1069  * ext3_xattr_delete_inode()
1070  *
1071  * Free extended attribute resources associated with this inode. This
1072  * is called immediately before an inode is freed. We have exclusive
1073  * access to the inode.
1074  */
1075 void
1076 ext3_xattr_delete_inode(handle_t *handle, struct inode *inode)
1077 {
1078         struct buffer_head *bh = NULL;
1079
1080         if (!EXT3_I(inode)->i_file_acl)
1081                 goto cleanup;
1082         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
1083         if (!bh) {
1084                 ext3_error(inode->i_sb, __FUNCTION__,
1085                         "inode %lu: block "E3FSBLK" read error", inode->i_ino,
1086                         EXT3_I(inode)->i_file_acl);
1087                 goto cleanup;
1088         }
1089         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
1090             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1091                 ext3_error(inode->i_sb, __FUNCTION__,
1092                         "inode %lu: bad block "E3FSBLK, inode->i_ino,
1093                         EXT3_I(inode)->i_file_acl);
1094                 goto cleanup;
1095         }
1096         ext3_xattr_release_block(handle, inode, bh);
1097         EXT3_I(inode)->i_file_acl = 0;
1098
1099 cleanup:
1100         brelse(bh);
1101 }
1102
1103 /*
1104  * ext3_xattr_put_super()
1105  *
1106  * This is called when a file system is unmounted.
1107  */
1108 void
1109 ext3_xattr_put_super(struct super_block *sb)
1110 {
1111         mb_cache_shrink(sb->s_bdev);
1112 }
1113
1114 /*
1115  * ext3_xattr_cache_insert()
1116  *
1117  * Create a new entry in the extended attribute cache, and insert
1118  * it unless such an entry is already in the cache.
1119  *
1120  * Returns 0, or a negative error number on failure.
1121  */
1122 static void
1123 ext3_xattr_cache_insert(struct buffer_head *bh)
1124 {
1125         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1126         struct mb_cache_entry *ce;
1127         int error;
1128
1129         ce = mb_cache_entry_alloc(ext3_xattr_cache, GFP_NOFS);
1130         if (!ce) {
1131                 ea_bdebug(bh, "out of memory");
1132                 return;
1133         }
1134         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
1135         if (error) {
1136                 mb_cache_entry_free(ce);
1137                 if (error == -EBUSY) {
1138                         ea_bdebug(bh, "already in cache");
1139                         error = 0;
1140                 }
1141         } else {
1142                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1143                 mb_cache_entry_release(ce);
1144         }
1145 }
1146
1147 /*
1148  * ext3_xattr_cmp()
1149  *
1150  * Compare two extended attribute blocks for equality.
1151  *
1152  * Returns 0 if the blocks are equal, 1 if they differ, and
1153  * a negative error number on errors.
1154  */
1155 static int
1156 ext3_xattr_cmp(struct ext3_xattr_header *header1,
1157                struct ext3_xattr_header *header2)
1158 {
1159         struct ext3_xattr_entry *entry1, *entry2;
1160
1161         entry1 = ENTRY(header1+1);
1162         entry2 = ENTRY(header2+1);
1163         while (!IS_LAST_ENTRY(entry1)) {
1164                 if (IS_LAST_ENTRY(entry2))
1165                         return 1;
1166                 if (entry1->e_hash != entry2->e_hash ||
1167                     entry1->e_name_index != entry2->e_name_index ||
1168                     entry1->e_name_len != entry2->e_name_len ||
1169                     entry1->e_value_size != entry2->e_value_size ||
1170                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1171                         return 1;
1172                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1173                         return -EIO;
1174                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1175                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1176                            le32_to_cpu(entry1->e_value_size)))
1177                         return 1;
1178
1179                 entry1 = EXT3_XATTR_NEXT(entry1);
1180                 entry2 = EXT3_XATTR_NEXT(entry2);
1181         }
1182         if (!IS_LAST_ENTRY(entry2))
1183                 return 1;
1184         return 0;
1185 }
1186
1187 /*
1188  * ext3_xattr_cache_find()
1189  *
1190  * Find an identical extended attribute block.
1191  *
1192  * Returns a pointer to the block found, or NULL if such a block was
1193  * not found or an error occurred.
1194  */
1195 static struct buffer_head *
1196 ext3_xattr_cache_find(struct inode *inode, struct ext3_xattr_header *header,
1197                       struct mb_cache_entry **pce)
1198 {
1199         __u32 hash = le32_to_cpu(header->h_hash);
1200         struct mb_cache_entry *ce;
1201
1202         if (!header->h_hash)
1203                 return NULL;  /* never share */
1204         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1205 again:
1206         ce = mb_cache_entry_find_first(ext3_xattr_cache, 0,
1207                                        inode->i_sb->s_bdev, hash);
1208         while (ce) {
1209                 struct buffer_head *bh;
1210
1211                 if (IS_ERR(ce)) {
1212                         if (PTR_ERR(ce) == -EAGAIN)
1213                                 goto again;
1214                         break;
1215                 }
1216                 bh = sb_bread(inode->i_sb, ce->e_block);
1217                 if (!bh) {
1218                         ext3_error(inode->i_sb, __FUNCTION__,
1219                                 "inode %lu: block %lu read error",
1220                                 inode->i_ino, (unsigned long) ce->e_block);
1221                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1222                                 EXT3_XATTR_REFCOUNT_MAX) {
1223                         ea_idebug(inode, "block %lu refcount %d>=%d",
1224                                   (unsigned long) ce->e_block,
1225                                   le32_to_cpu(BHDR(bh)->h_refcount),
1226                                           EXT3_XATTR_REFCOUNT_MAX);
1227                 } else if (ext3_xattr_cmp(header, BHDR(bh)) == 0) {
1228                         *pce = ce;
1229                         return bh;
1230                 }
1231                 brelse(bh);
1232                 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
1233         }
1234         return NULL;
1235 }
1236
1237 #define NAME_HASH_SHIFT 5
1238 #define VALUE_HASH_SHIFT 16
1239
1240 /*
1241  * ext3_xattr_hash_entry()
1242  *
1243  * Compute the hash of an extended attribute.
1244  */
1245 static inline void ext3_xattr_hash_entry(struct ext3_xattr_header *header,
1246                                          struct ext3_xattr_entry *entry)
1247 {
1248         __u32 hash = 0;
1249         char *name = entry->e_name;
1250         int n;
1251
1252         for (n=0; n < entry->e_name_len; n++) {
1253                 hash = (hash << NAME_HASH_SHIFT) ^
1254                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1255                        *name++;
1256         }
1257
1258         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1259                 __le32 *value = (__le32 *)((char *)header +
1260                         le16_to_cpu(entry->e_value_offs));
1261                 for (n = (le32_to_cpu(entry->e_value_size) +
1262                      EXT3_XATTR_ROUND) >> EXT3_XATTR_PAD_BITS; n; n--) {
1263                         hash = (hash << VALUE_HASH_SHIFT) ^
1264                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1265                                le32_to_cpu(*value++);
1266                 }
1267         }
1268         entry->e_hash = cpu_to_le32(hash);
1269 }
1270
1271 #undef NAME_HASH_SHIFT
1272 #undef VALUE_HASH_SHIFT
1273
1274 #define BLOCK_HASH_SHIFT 16
1275
1276 /*
1277  * ext3_xattr_rehash()
1278  *
1279  * Re-compute the extended attribute hash value after an entry has changed.
1280  */
1281 static void ext3_xattr_rehash(struct ext3_xattr_header *header,
1282                               struct ext3_xattr_entry *entry)
1283 {
1284         struct ext3_xattr_entry *here;
1285         __u32 hash = 0;
1286
1287         ext3_xattr_hash_entry(header, entry);
1288         here = ENTRY(header+1);
1289         while (!IS_LAST_ENTRY(here)) {
1290                 if (!here->e_hash) {
1291                         /* Block is not shared if an entry's hash value == 0 */
1292                         hash = 0;
1293                         break;
1294                 }
1295                 hash = (hash << BLOCK_HASH_SHIFT) ^
1296                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1297                        le32_to_cpu(here->e_hash);
1298                 here = EXT3_XATTR_NEXT(here);
1299         }
1300         header->h_hash = cpu_to_le32(hash);
1301 }
1302
1303 #undef BLOCK_HASH_SHIFT
1304
1305 int __init
1306 init_ext3_xattr(void)
1307 {
1308         ext3_xattr_cache = mb_cache_create("ext3_xattr", NULL,
1309                 sizeof(struct mb_cache_entry) +
1310                 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1311         if (!ext3_xattr_cache)
1312                 return -ENOMEM;
1313         return 0;
1314 }
1315
1316 void
1317 exit_ext3_xattr(void)
1318 {
1319         if (ext3_xattr_cache)
1320                 mb_cache_destroy(ext3_xattr_cache);
1321         ext3_xattr_cache = NULL;
1322 }