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TOMOYO Linux Cross Reference
Linux/fs/ext3/xattr.c

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  1 /*
  2  * linux/fs/ext3/xattr.c
  3  *
  4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
  5  *
  6  * Fix by Harrison Xing <harrison@mountainviewdata.com>.
  7  * Ext3 code with a lot of help from Eric Jarman <ejarman@acm.org>.
  8  * Extended attributes for symlinks and special files added per
  9  *  suggestion of Luka Renko <luka.renko@hermes.si>.
 10  * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
 11  *  Red Hat Inc.
 12  * ea-in-inode support by Alex Tomas <alex@clusterfs.com> aka bzzz
 13  *  and Andreas Gruenbacher <agruen@suse.de>.
 14  */
 15 
 16 /*
 17  * Extended attributes are stored directly in inodes (on file systems with
 18  * inodes bigger than 128 bytes) and on additional disk blocks. The i_file_acl
 19  * field contains the block number if an inode uses an additional block. All
 20  * attributes must fit in the inode and one additional block. Blocks that
 21  * contain the identical set of attributes may be shared among several inodes.
 22  * Identical blocks are detected by keeping a cache of blocks that have
 23  * recently been accessed.
 24  *
 25  * The attributes in inodes and on blocks have a different header; the entries
 26  * are stored in the same format:
 27  *
 28  *   +------------------+
 29  *   | header           |
 30  *   | entry 1          | |
 31  *   | entry 2          | | growing downwards
 32  *   | entry 3          | v
 33  *   | four null bytes  |
 34  *   | . . .            |
 35  *   | value 1          | ^
 36  *   | value 3          | | growing upwards
 37  *   | value 2          | |
 38  *   +------------------+
 39  *
 40  * The header is followed by multiple entry descriptors. In disk blocks, the
 41  * entry descriptors are kept sorted. In inodes, they are unsorted. The
 42  * attribute values are aligned to the end of the block in no specific order.
 43  *
 44  * Locking strategy
 45  * ----------------
 46  * EXT3_I(inode)->i_file_acl is protected by EXT3_I(inode)->xattr_sem.
 47  * EA blocks are only changed if they are exclusive to an inode, so
 48  * holding xattr_sem also means that nothing but the EA block's reference
 49  * count can change. Multiple writers to the same block are synchronized
 50  * by the buffer lock.
 51  */
 52 
 53 #include "ext3.h"
 54 #include <linux/mbcache.h>
 55 #include <linux/quotaops.h>
 56 #include "xattr.h"
 57 #include "acl.h"
 58 
 59 #define BHDR(bh) ((struct ext3_xattr_header *)((bh)->b_data))
 60 #define ENTRY(ptr) ((struct ext3_xattr_entry *)(ptr))
 61 #define BFIRST(bh) ENTRY(BHDR(bh)+1)
 62 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
 63 
 64 #define IHDR(inode, raw_inode) \
 65         ((struct ext3_xattr_ibody_header *) \
 66                 ((void *)raw_inode + \
 67                  EXT3_GOOD_OLD_INODE_SIZE + \
 68                  EXT3_I(inode)->i_extra_isize))
 69 #define IFIRST(hdr) ((struct ext3_xattr_entry *)((hdr)+1))
 70 
 71 #ifdef EXT3_XATTR_DEBUG
 72 # define ea_idebug(inode, f...) do { \
 73                 printk(KERN_DEBUG "inode %s:%lu: ", \
 74                         inode->i_sb->s_id, inode->i_ino); \
 75                 printk(f); \
 76                 printk("\n"); \
 77         } while (0)
 78 # define ea_bdebug(bh, f...) do { \
 79                 char b[BDEVNAME_SIZE]; \
 80                 printk(KERN_DEBUG "block %s:%lu: ", \
 81                         bdevname(bh->b_bdev, b), \
 82                         (unsigned long) bh->b_blocknr); \
 83                 printk(f); \
 84                 printk("\n"); \
 85         } while (0)
 86 #else
 87 # define ea_idebug(f...)
 88 # define ea_bdebug(f...)
 89 #endif
 90 
 91 static void ext3_xattr_cache_insert(struct buffer_head *);
 92 static struct buffer_head *ext3_xattr_cache_find(struct inode *,
 93                                                  struct ext3_xattr_header *,
 94                                                  struct mb_cache_entry **);
 95 static void ext3_xattr_rehash(struct ext3_xattr_header *,
 96                               struct ext3_xattr_entry *);
 97 static int ext3_xattr_list(struct dentry *dentry, char *buffer,
 98                            size_t buffer_size);
 99 
100 static struct mb_cache *ext3_xattr_cache;
101 
102 static const struct xattr_handler *ext3_xattr_handler_map[] = {
103         [EXT3_XATTR_INDEX_USER]              = &ext3_xattr_user_handler,
104 #ifdef CONFIG_EXT3_FS_POSIX_ACL
105         [EXT3_XATTR_INDEX_POSIX_ACL_ACCESS]  = &posix_acl_access_xattr_handler,
106         [EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
107 #endif
108         [EXT3_XATTR_INDEX_TRUSTED]           = &ext3_xattr_trusted_handler,
109 #ifdef CONFIG_EXT3_FS_SECURITY
110         [EXT3_XATTR_INDEX_SECURITY]          = &ext3_xattr_security_handler,
111 #endif
112 };
113 
114 const struct xattr_handler *ext3_xattr_handlers[] = {
115         &ext3_xattr_user_handler,
116         &ext3_xattr_trusted_handler,
117 #ifdef CONFIG_EXT3_FS_POSIX_ACL
118         &posix_acl_access_xattr_handler,
119         &posix_acl_default_xattr_handler,
120 #endif
121 #ifdef CONFIG_EXT3_FS_SECURITY
122         &ext3_xattr_security_handler,
123 #endif
124         NULL
125 };
126 
127 static inline const struct xattr_handler *
128 ext3_xattr_handler(int name_index)
129 {
130         const struct xattr_handler *handler = NULL;
131 
132         if (name_index > 0 && name_index < ARRAY_SIZE(ext3_xattr_handler_map))
133                 handler = ext3_xattr_handler_map[name_index];
134         return handler;
135 }
136 
137 /*
138  * Inode operation listxattr()
139  *
140  * dentry->d_inode->i_mutex: don't care
141  */
142 ssize_t
143 ext3_listxattr(struct dentry *dentry, char *buffer, size_t size)
144 {
145         return ext3_xattr_list(dentry, buffer, size);
146 }
147 
148 static int
149 ext3_xattr_check_names(struct ext3_xattr_entry *entry, void *end)
150 {
151         while (!IS_LAST_ENTRY(entry)) {
152                 struct ext3_xattr_entry *next = EXT3_XATTR_NEXT(entry);
153                 if ((void *)next >= end)
154                         return -EIO;
155                 entry = next;
156         }
157         return 0;
158 }
159 
160 static inline int
161 ext3_xattr_check_block(struct buffer_head *bh)
162 {
163         int error;
164 
165         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
166             BHDR(bh)->h_blocks != cpu_to_le32(1))
167                 return -EIO;
168         error = ext3_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
169         return error;
170 }
171 
172 static inline int
173 ext3_xattr_check_entry(struct ext3_xattr_entry *entry, size_t size)
174 {
175         size_t value_size = le32_to_cpu(entry->e_value_size);
176 
177         if (entry->e_value_block != 0 || value_size > size ||
178             le16_to_cpu(entry->e_value_offs) + value_size > size)
179                 return -EIO;
180         return 0;
181 }
182 
183 static int
184 ext3_xattr_find_entry(struct ext3_xattr_entry **pentry, int name_index,
185                       const char *name, size_t size, int sorted)
186 {
187         struct ext3_xattr_entry *entry;
188         size_t name_len;
189         int cmp = 1;
190 
191         if (name == NULL)
192                 return -EINVAL;
193         name_len = strlen(name);
194         entry = *pentry;
195         for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
196                 cmp = name_index - entry->e_name_index;
197                 if (!cmp)
198                         cmp = name_len - entry->e_name_len;
199                 if (!cmp)
200                         cmp = memcmp(name, entry->e_name, name_len);
201                 if (cmp <= 0 && (sorted || cmp == 0))
202                         break;
203         }
204         *pentry = entry;
205         if (!cmp && ext3_xattr_check_entry(entry, size))
206                         return -EIO;
207         return cmp ? -ENODATA : 0;
208 }
209 
210 static int
211 ext3_xattr_block_get(struct inode *inode, int name_index, const char *name,
212                      void *buffer, size_t buffer_size)
213 {
214         struct buffer_head *bh = NULL;
215         struct ext3_xattr_entry *entry;
216         size_t size;
217         int error;
218 
219         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
220                   name_index, name, buffer, (long)buffer_size);
221 
222         error = -ENODATA;
223         if (!EXT3_I(inode)->i_file_acl)
224                 goto cleanup;
225         ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
226         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
227         if (!bh)
228                 goto cleanup;
229         ea_bdebug(bh, "b_count=%d, refcount=%d",
230                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
231         if (ext3_xattr_check_block(bh)) {
232 bad_block:      ext3_error(inode->i_sb, __func__,
233                            "inode %lu: bad block "E3FSBLK, inode->i_ino,
234                            EXT3_I(inode)->i_file_acl);
235                 error = -EIO;
236                 goto cleanup;
237         }
238         ext3_xattr_cache_insert(bh);
239         entry = BFIRST(bh);
240         error = ext3_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
241         if (error == -EIO)
242                 goto bad_block;
243         if (error)
244                 goto cleanup;
245         size = le32_to_cpu(entry->e_value_size);
246         if (buffer) {
247                 error = -ERANGE;
248                 if (size > buffer_size)
249                         goto cleanup;
250                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
251                        size);
252         }
253         error = size;
254 
255 cleanup:
256         brelse(bh);
257         return error;
258 }
259 
260 static int
261 ext3_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
262                      void *buffer, size_t buffer_size)
263 {
264         struct ext3_xattr_ibody_header *header;
265         struct ext3_xattr_entry *entry;
266         struct ext3_inode *raw_inode;
267         struct ext3_iloc iloc;
268         size_t size;
269         void *end;
270         int error;
271 
272         if (!ext3_test_inode_state(inode, EXT3_STATE_XATTR))
273                 return -ENODATA;
274         error = ext3_get_inode_loc(inode, &iloc);
275         if (error)
276                 return error;
277         raw_inode = ext3_raw_inode(&iloc);
278         header = IHDR(inode, raw_inode);
279         entry = IFIRST(header);
280         end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
281         error = ext3_xattr_check_names(entry, end);
282         if (error)
283                 goto cleanup;
284         error = ext3_xattr_find_entry(&entry, name_index, name,
285                                       end - (void *)entry, 0);
286         if (error)
287                 goto cleanup;
288         size = le32_to_cpu(entry->e_value_size);
289         if (buffer) {
290                 error = -ERANGE;
291                 if (size > buffer_size)
292                         goto cleanup;
293                 memcpy(buffer, (void *)IFIRST(header) +
294                        le16_to_cpu(entry->e_value_offs), size);
295         }
296         error = size;
297 
298 cleanup:
299         brelse(iloc.bh);
300         return error;
301 }
302 
303 /*
304  * ext3_xattr_get()
305  *
306  * Copy an extended attribute into the buffer
307  * provided, or compute the buffer size required.
308  * Buffer is NULL to compute the size of the buffer required.
309  *
310  * Returns a negative error number on failure, or the number of bytes
311  * used / required on success.
312  */
313 int
314 ext3_xattr_get(struct inode *inode, int name_index, const char *name,
315                void *buffer, size_t buffer_size)
316 {
317         int error;
318 
319         down_read(&EXT3_I(inode)->xattr_sem);
320         error = ext3_xattr_ibody_get(inode, name_index, name, buffer,
321                                      buffer_size);
322         if (error == -ENODATA)
323                 error = ext3_xattr_block_get(inode, name_index, name, buffer,
324                                              buffer_size);
325         up_read(&EXT3_I(inode)->xattr_sem);
326         return error;
327 }
328 
329 static int
330 ext3_xattr_list_entries(struct dentry *dentry, struct ext3_xattr_entry *entry,
331                         char *buffer, size_t buffer_size)
332 {
333         size_t rest = buffer_size;
334 
335         for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
336                 const struct xattr_handler *handler =
337                         ext3_xattr_handler(entry->e_name_index);
338 
339                 if (handler) {
340                         size_t size = handler->list(dentry, buffer, rest,
341                                                     entry->e_name,
342                                                     entry->e_name_len,
343                                                     handler->flags);
344                         if (buffer) {
345                                 if (size > rest)
346                                         return -ERANGE;
347                                 buffer += size;
348                         }
349                         rest -= size;
350                 }
351         }
352         return buffer_size - rest;
353 }
354 
355 static int
356 ext3_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
357 {
358         struct inode *inode = dentry->d_inode;
359         struct buffer_head *bh = NULL;
360         int error;
361 
362         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
363                   buffer, (long)buffer_size);
364 
365         error = 0;
366         if (!EXT3_I(inode)->i_file_acl)
367                 goto cleanup;
368         ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
369         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
370         error = -EIO;
371         if (!bh)
372                 goto cleanup;
373         ea_bdebug(bh, "b_count=%d, refcount=%d",
374                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
375         if (ext3_xattr_check_block(bh)) {
376                 ext3_error(inode->i_sb, __func__,
377                            "inode %lu: bad block "E3FSBLK, inode->i_ino,
378                            EXT3_I(inode)->i_file_acl);
379                 error = -EIO;
380                 goto cleanup;
381         }
382         ext3_xattr_cache_insert(bh);
383         error = ext3_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
384 
385 cleanup:
386         brelse(bh);
387 
388         return error;
389 }
390 
391 static int
392 ext3_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
393 {
394         struct inode *inode = dentry->d_inode;
395         struct ext3_xattr_ibody_header *header;
396         struct ext3_inode *raw_inode;
397         struct ext3_iloc iloc;
398         void *end;
399         int error;
400 
401         if (!ext3_test_inode_state(inode, EXT3_STATE_XATTR))
402                 return 0;
403         error = ext3_get_inode_loc(inode, &iloc);
404         if (error)
405                 return error;
406         raw_inode = ext3_raw_inode(&iloc);
407         header = IHDR(inode, raw_inode);
408         end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
409         error = ext3_xattr_check_names(IFIRST(header), end);
410         if (error)
411                 goto cleanup;
412         error = ext3_xattr_list_entries(dentry, IFIRST(header),
413                                         buffer, buffer_size);
414 
415 cleanup:
416         brelse(iloc.bh);
417         return error;
418 }
419 
420 /*
421  * ext3_xattr_list()
422  *
423  * Copy a list of attribute names into the buffer
424  * provided, or compute the buffer size required.
425  * Buffer is NULL to compute the size of the buffer required.
426  *
427  * Returns a negative error number on failure, or the number of bytes
428  * used / required on success.
429  */
430 static int
431 ext3_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
432 {
433         int i_error, b_error;
434 
435         down_read(&EXT3_I(dentry->d_inode)->xattr_sem);
436         i_error = ext3_xattr_ibody_list(dentry, buffer, buffer_size);
437         if (i_error < 0) {
438                 b_error = 0;
439         } else {
440                 if (buffer) {
441                         buffer += i_error;
442                         buffer_size -= i_error;
443                 }
444                 b_error = ext3_xattr_block_list(dentry, buffer, buffer_size);
445                 if (b_error < 0)
446                         i_error = 0;
447         }
448         up_read(&EXT3_I(dentry->d_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                 ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
465         }
466 }
467 
468 /*
469  * Release the xattr block BH: If the reference count is > 1, decrement
470  * it; otherwise free the block.
471  */
472 static void
473 ext3_xattr_release_block(handle_t *handle, struct inode *inode,
474                          struct buffer_head *bh)
475 {
476         struct mb_cache_entry *ce = NULL;
477         int error = 0;
478 
479         ce = mb_cache_entry_get(ext3_xattr_cache, bh->b_bdev, bh->b_blocknr);
480         error = ext3_journal_get_write_access(handle, bh);
481         if (error)
482                  goto out;
483 
484         lock_buffer(bh);
485 
486         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
487                 ea_bdebug(bh, "refcount now=0; freeing");
488                 if (ce)
489                         mb_cache_entry_free(ce);
490                 ext3_free_blocks(handle, inode, bh->b_blocknr, 1);
491                 get_bh(bh);
492                 ext3_forget(handle, 1, inode, bh, bh->b_blocknr);
493         } else {
494                 le32_add_cpu(&BHDR(bh)->h_refcount, -1);
495                 error = ext3_journal_dirty_metadata(handle, bh);
496                 if (IS_SYNC(inode))
497                         handle->h_sync = 1;
498                 dquot_free_block(inode, 1);
499                 ea_bdebug(bh, "refcount now=%d; releasing",
500                           le32_to_cpu(BHDR(bh)->h_refcount));
501                 if (ce)
502                         mb_cache_entry_release(ce);
503         }
504         unlock_buffer(bh);
505 out:
506         ext3_std_error(inode->i_sb, error);
507         return;
508 }
509 
510 struct ext3_xattr_info {
511         int name_index;
512         const char *name;
513         const void *value;
514         size_t value_len;
515 };
516 
517 struct ext3_xattr_search {
518         struct ext3_xattr_entry *first;
519         void *base;
520         void *end;
521         struct ext3_xattr_entry *here;
522         int not_found;
523 };
524 
525 static int
526 ext3_xattr_set_entry(struct ext3_xattr_info *i, struct ext3_xattr_search *s)
527 {
528         struct ext3_xattr_entry *last;
529         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
530 
531         /* Compute min_offs and last. */
532         last = s->first;
533         for (; !IS_LAST_ENTRY(last); last = EXT3_XATTR_NEXT(last)) {
534                 if (!last->e_value_block && last->e_value_size) {
535                         size_t offs = le16_to_cpu(last->e_value_offs);
536                         if (offs < min_offs)
537                                 min_offs = offs;
538                 }
539         }
540         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
541         if (!s->not_found) {
542                 if (!s->here->e_value_block && s->here->e_value_size) {
543                         size_t size = le32_to_cpu(s->here->e_value_size);
544                         free += EXT3_XATTR_SIZE(size);
545                 }
546                 free += EXT3_XATTR_LEN(name_len);
547         }
548         if (i->value) {
549                 if (free < EXT3_XATTR_SIZE(i->value_len) ||
550                     free < EXT3_XATTR_LEN(name_len) +
551                            EXT3_XATTR_SIZE(i->value_len))
552                         return -ENOSPC;
553         }
554 
555         if (i->value && s->not_found) {
556                 /* Insert the new name. */
557                 size_t size = EXT3_XATTR_LEN(name_len);
558                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
559                 memmove((void *)s->here + size, s->here, rest);
560                 memset(s->here, 0, size);
561                 s->here->e_name_index = i->name_index;
562                 s->here->e_name_len = name_len;
563                 memcpy(s->here->e_name, i->name, name_len);
564         } else {
565                 if (!s->here->e_value_block && s->here->e_value_size) {
566                         void *first_val = s->base + min_offs;
567                         size_t offs = le16_to_cpu(s->here->e_value_offs);
568                         void *val = s->base + offs;
569                         size_t size = EXT3_XATTR_SIZE(
570                                 le32_to_cpu(s->here->e_value_size));
571 
572                         if (i->value && size == EXT3_XATTR_SIZE(i->value_len)) {
573                                 /* The old and the new value have the same
574                                    size. Just replace. */
575                                 s->here->e_value_size =
576                                         cpu_to_le32(i->value_len);
577                                 memset(val + size - EXT3_XATTR_PAD, 0,
578                                        EXT3_XATTR_PAD); /* Clear pad bytes. */
579                                 memcpy(val, i->value, i->value_len);
580                                 return 0;
581                         }
582 
583                         /* Remove the old value. */
584                         memmove(first_val + size, first_val, val - first_val);
585                         memset(first_val, 0, size);
586                         s->here->e_value_size = 0;
587                         s->here->e_value_offs = 0;
588                         min_offs += size;
589 
590                         /* Adjust all value offsets. */
591                         last = s->first;
592                         while (!IS_LAST_ENTRY(last)) {
593                                 size_t o = le16_to_cpu(last->e_value_offs);
594                                 if (!last->e_value_block &&
595                                     last->e_value_size && o < offs)
596                                         last->e_value_offs =
597                                                 cpu_to_le16(o + size);
598                                 last = EXT3_XATTR_NEXT(last);
599                         }
600                 }
601                 if (!i->value) {
602                         /* Remove the old name. */
603                         size_t size = EXT3_XATTR_LEN(name_len);
604                         last = ENTRY((void *)last - size);
605                         memmove(s->here, (void *)s->here + size,
606                                 (void *)last - (void *)s->here + sizeof(__u32));
607                         memset(last, 0, size);
608                 }
609         }
610 
611         if (i->value) {
612                 /* Insert the new value. */
613                 s->here->e_value_size = cpu_to_le32(i->value_len);
614                 if (i->value_len) {
615                         size_t size = EXT3_XATTR_SIZE(i->value_len);
616                         void *val = s->base + min_offs - size;
617                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
618                         memset(val + size - EXT3_XATTR_PAD, 0,
619                                EXT3_XATTR_PAD); /* Clear the pad bytes. */
620                         memcpy(val, i->value, i->value_len);
621                 }
622         }
623         return 0;
624 }
625 
626 struct ext3_xattr_block_find {
627         struct ext3_xattr_search s;
628         struct buffer_head *bh;
629 };
630 
631 static int
632 ext3_xattr_block_find(struct inode *inode, struct ext3_xattr_info *i,
633                       struct ext3_xattr_block_find *bs)
634 {
635         struct super_block *sb = inode->i_sb;
636         int error;
637 
638         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
639                   i->name_index, i->name, i->value, (long)i->value_len);
640 
641         if (EXT3_I(inode)->i_file_acl) {
642                 /* The inode already has an extended attribute block. */
643                 bs->bh = sb_bread(sb, EXT3_I(inode)->i_file_acl);
644                 error = -EIO;
645                 if (!bs->bh)
646                         goto cleanup;
647                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
648                         atomic_read(&(bs->bh->b_count)),
649                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
650                 if (ext3_xattr_check_block(bs->bh)) {
651                         ext3_error(sb, __func__,
652                                 "inode %lu: bad block "E3FSBLK, inode->i_ino,
653                                 EXT3_I(inode)->i_file_acl);
654                         error = -EIO;
655                         goto cleanup;
656                 }
657                 /* Find the named attribute. */
658                 bs->s.base = BHDR(bs->bh);
659                 bs->s.first = BFIRST(bs->bh);
660                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
661                 bs->s.here = bs->s.first;
662                 error = ext3_xattr_find_entry(&bs->s.here, i->name_index,
663                                               i->name, bs->bh->b_size, 1);
664                 if (error && error != -ENODATA)
665                         goto cleanup;
666                 bs->s.not_found = error;
667         }
668         error = 0;
669 
670 cleanup:
671         return error;
672 }
673 
674 static int
675 ext3_xattr_block_set(handle_t *handle, struct inode *inode,
676                      struct ext3_xattr_info *i,
677                      struct ext3_xattr_block_find *bs)
678 {
679         struct super_block *sb = inode->i_sb;
680         struct buffer_head *new_bh = NULL;
681         struct ext3_xattr_search *s = &bs->s;
682         struct mb_cache_entry *ce = NULL;
683         int error = 0;
684 
685 #define header(x) ((struct ext3_xattr_header *)(x))
686 
687         if (i->value && i->value_len > sb->s_blocksize)
688                 return -ENOSPC;
689         if (s->base) {
690                 ce = mb_cache_entry_get(ext3_xattr_cache, bs->bh->b_bdev,
691                                         bs->bh->b_blocknr);
692                 error = ext3_journal_get_write_access(handle, bs->bh);
693                 if (error)
694                         goto cleanup;
695                 lock_buffer(bs->bh);
696 
697                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
698                         if (ce) {
699                                 mb_cache_entry_free(ce);
700                                 ce = NULL;
701                         }
702                         ea_bdebug(bs->bh, "modifying in-place");
703                         error = ext3_xattr_set_entry(i, s);
704                         if (!error) {
705                                 if (!IS_LAST_ENTRY(s->first))
706                                         ext3_xattr_rehash(header(s->base),
707                                                           s->here);
708                                 ext3_xattr_cache_insert(bs->bh);
709                         }
710                         unlock_buffer(bs->bh);
711                         if (error == -EIO)
712                                 goto bad_block;
713                         if (!error)
714                                 error = ext3_journal_dirty_metadata(handle,
715                                                                     bs->bh);
716                         if (error)
717                                 goto cleanup;
718                         goto inserted;
719                 } else {
720                         int offset = (char *)s->here - bs->bh->b_data;
721 
722                         unlock_buffer(bs->bh);
723                         journal_release_buffer(handle, bs->bh);
724 
725                         if (ce) {
726                                 mb_cache_entry_release(ce);
727                                 ce = NULL;
728                         }
729                         ea_bdebug(bs->bh, "cloning");
730                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
731                         error = -ENOMEM;
732                         if (s->base == NULL)
733                                 goto cleanup;
734                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
735                         s->first = ENTRY(header(s->base)+1);
736                         header(s->base)->h_refcount = cpu_to_le32(1);
737                         s->here = ENTRY(s->base + offset);
738                         s->end = s->base + bs->bh->b_size;
739                 }
740         } else {
741                 /* Allocate a buffer where we construct the new block. */
742                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
743                 /* assert(header == s->base) */
744                 error = -ENOMEM;
745                 if (s->base == NULL)
746                         goto cleanup;
747                 header(s->base)->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
748                 header(s->base)->h_blocks = cpu_to_le32(1);
749                 header(s->base)->h_refcount = cpu_to_le32(1);
750                 s->first = ENTRY(header(s->base)+1);
751                 s->here = ENTRY(header(s->base)+1);
752                 s->end = s->base + sb->s_blocksize;
753         }
754 
755         error = ext3_xattr_set_entry(i, s);
756         if (error == -EIO)
757                 goto bad_block;
758         if (error)
759                 goto cleanup;
760         if (!IS_LAST_ENTRY(s->first))
761                 ext3_xattr_rehash(header(s->base), s->here);
762 
763 inserted:
764         if (!IS_LAST_ENTRY(s->first)) {
765                 new_bh = ext3_xattr_cache_find(inode, header(s->base), &ce);
766                 if (new_bh) {
767                         /* We found an identical block in the cache. */
768                         if (new_bh == bs->bh)
769                                 ea_bdebug(new_bh, "keeping");
770                         else {
771                                 /* The old block is released after updating
772                                    the inode. */
773                                 error = dquot_alloc_block(inode, 1);
774                                 if (error)
775                                         goto cleanup;
776                                 error = ext3_journal_get_write_access(handle,
777                                                                       new_bh);
778                                 if (error)
779                                         goto cleanup_dquot;
780                                 lock_buffer(new_bh);
781                                 le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
782                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
783                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
784                                 unlock_buffer(new_bh);
785                                 error = ext3_journal_dirty_metadata(handle,
786                                                                     new_bh);
787                                 if (error)
788                                         goto cleanup_dquot;
789                         }
790                         mb_cache_entry_release(ce);
791                         ce = NULL;
792                 } else if (bs->bh && s->base == bs->bh->b_data) {
793                         /* We were modifying this block in-place. */
794                         ea_bdebug(bs->bh, "keeping this block");
795                         new_bh = bs->bh;
796                         get_bh(new_bh);
797                 } else {
798                         /* We need to allocate a new block */
799                         ext3_fsblk_t goal = ext3_group_first_block_no(sb,
800                                                 EXT3_I(inode)->i_block_group);
801                         ext3_fsblk_t block;
802 
803                         /*
804                          * Protect us agaist concurrent allocations to the
805                          * same inode from ext3_..._writepage(). Reservation
806                          * code does not expect racing allocations.
807                          */
808                         mutex_lock(&EXT3_I(inode)->truncate_mutex);
809                         block = ext3_new_block(handle, inode, goal, &error);
810                         mutex_unlock(&EXT3_I(inode)->truncate_mutex);
811                         if (error)
812                                 goto cleanup;
813                         ea_idebug(inode, "creating block %d", block);
814 
815                         new_bh = sb_getblk(sb, block);
816                         if (unlikely(!new_bh)) {
817 getblk_failed:
818                                 ext3_free_blocks(handle, inode, block, 1);
819                                 error = -ENOMEM;
820                                 goto cleanup;
821                         }
822                         lock_buffer(new_bh);
823                         error = ext3_journal_get_create_access(handle, new_bh);
824                         if (error) {
825                                 unlock_buffer(new_bh);
826                                 goto getblk_failed;
827                         }
828                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
829                         set_buffer_uptodate(new_bh);
830                         unlock_buffer(new_bh);
831                         ext3_xattr_cache_insert(new_bh);
832                         error = ext3_journal_dirty_metadata(handle, new_bh);
833                         if (error)
834                                 goto cleanup;
835                 }
836         }
837 
838         /* Update the inode. */
839         EXT3_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
840 
841         /* Drop the previous xattr block. */
842         if (bs->bh && bs->bh != new_bh)
843                 ext3_xattr_release_block(handle, inode, bs->bh);
844         error = 0;
845 
846 cleanup:
847         if (ce)
848                 mb_cache_entry_release(ce);
849         brelse(new_bh);
850         if (!(bs->bh && s->base == bs->bh->b_data))
851                 kfree(s->base);
852 
853         return error;
854 
855 cleanup_dquot:
856         dquot_free_block(inode, 1);
857         goto cleanup;
858 
859 bad_block:
860         ext3_error(inode->i_sb, __func__,
861                    "inode %lu: bad block "E3FSBLK, inode->i_ino,
862                    EXT3_I(inode)->i_file_acl);
863         goto cleanup;
864 
865 #undef header
866 }
867 
868 struct ext3_xattr_ibody_find {
869         struct ext3_xattr_search s;
870         struct ext3_iloc iloc;
871 };
872 
873 static int
874 ext3_xattr_ibody_find(struct inode *inode, struct ext3_xattr_info *i,
875                       struct ext3_xattr_ibody_find *is)
876 {
877         struct ext3_xattr_ibody_header *header;
878         struct ext3_inode *raw_inode;
879         int error;
880 
881         if (EXT3_I(inode)->i_extra_isize == 0)
882                 return 0;
883         raw_inode = ext3_raw_inode(&is->iloc);
884         header = IHDR(inode, raw_inode);
885         is->s.base = is->s.first = IFIRST(header);
886         is->s.here = is->s.first;
887         is->s.end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
888         if (ext3_test_inode_state(inode, EXT3_STATE_XATTR)) {
889                 error = ext3_xattr_check_names(IFIRST(header), is->s.end);
890                 if (error)
891                         return error;
892                 /* Find the named attribute. */
893                 error = ext3_xattr_find_entry(&is->s.here, i->name_index,
894                                               i->name, is->s.end -
895                                               (void *)is->s.base, 0);
896                 if (error && error != -ENODATA)
897                         return error;
898                 is->s.not_found = error;
899         }
900         return 0;
901 }
902 
903 static int
904 ext3_xattr_ibody_set(handle_t *handle, struct inode *inode,
905                      struct ext3_xattr_info *i,
906                      struct ext3_xattr_ibody_find *is)
907 {
908         struct ext3_xattr_ibody_header *header;
909         struct ext3_xattr_search *s = &is->s;
910         int error;
911 
912         if (EXT3_I(inode)->i_extra_isize == 0)
913                 return -ENOSPC;
914         error = ext3_xattr_set_entry(i, s);
915         if (error)
916                 return error;
917         header = IHDR(inode, ext3_raw_inode(&is->iloc));
918         if (!IS_LAST_ENTRY(s->first)) {
919                 header->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
920                 ext3_set_inode_state(inode, EXT3_STATE_XATTR);
921         } else {
922                 header->h_magic = cpu_to_le32(0);
923                 ext3_clear_inode_state(inode, EXT3_STATE_XATTR);
924         }
925         return 0;
926 }
927 
928 /*
929  * ext3_xattr_set_handle()
930  *
931  * Create, replace or remove an extended attribute for this inode.  Value
932  * is NULL to remove an existing extended attribute, and non-NULL to
933  * either replace an existing extended attribute, or create a new extended
934  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
935  * specify that an extended attribute must exist and must not exist
936  * previous to the call, respectively.
937  *
938  * Returns 0, or a negative error number on failure.
939  */
940 int
941 ext3_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
942                       const char *name, const void *value, size_t value_len,
943                       int flags)
944 {
945         struct ext3_xattr_info i = {
946                 .name_index = name_index,
947                 .name = name,
948                 .value = value,
949                 .value_len = value_len,
950 
951         };
952         struct ext3_xattr_ibody_find is = {
953                 .s = { .not_found = -ENODATA, },
954         };
955         struct ext3_xattr_block_find bs = {
956                 .s = { .not_found = -ENODATA, },
957         };
958         int error;
959 
960         if (!name)
961                 return -EINVAL;
962         if (strlen(name) > 255)
963                 return -ERANGE;
964         down_write(&EXT3_I(inode)->xattr_sem);
965         error = ext3_get_inode_loc(inode, &is.iloc);
966         if (error)
967                 goto cleanup;
968 
969         error = ext3_journal_get_write_access(handle, is.iloc.bh);
970         if (error)
971                 goto cleanup;
972 
973         if (ext3_test_inode_state(inode, EXT3_STATE_NEW)) {
974                 struct ext3_inode *raw_inode = ext3_raw_inode(&is.iloc);
975                 memset(raw_inode, 0, EXT3_SB(inode->i_sb)->s_inode_size);
976                 ext3_clear_inode_state(inode, EXT3_STATE_NEW);
977         }
978 
979         error = ext3_xattr_ibody_find(inode, &i, &is);
980         if (error)
981                 goto cleanup;
982         if (is.s.not_found)
983                 error = ext3_xattr_block_find(inode, &i, &bs);
984         if (error)
985                 goto cleanup;
986         if (is.s.not_found && bs.s.not_found) {
987                 error = -ENODATA;
988                 if (flags & XATTR_REPLACE)
989                         goto cleanup;
990                 error = 0;
991                 if (!value)
992                         goto cleanup;
993         } else {
994                 error = -EEXIST;
995                 if (flags & XATTR_CREATE)
996                         goto cleanup;
997         }
998         if (!value) {
999                 if (!is.s.not_found)
1000                         error = ext3_xattr_ibody_set(handle, inode, &i, &is);
1001                 else if (!bs.s.not_found)
1002                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1003         } else {
1004                 error = ext3_xattr_ibody_set(handle, inode, &i, &is);
1005                 if (!error && !bs.s.not_found) {
1006                         i.value = NULL;
1007                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1008                 } else if (error == -ENOSPC) {
1009                         if (EXT3_I(inode)->i_file_acl && !bs.s.base) {
1010                                 error = ext3_xattr_block_find(inode, &i, &bs);
1011                                 if (error)
1012                                         goto cleanup;
1013                         }
1014                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1015                         if (error)
1016                                 goto cleanup;
1017                         if (!is.s.not_found) {
1018                                 i.value = NULL;
1019                                 error = ext3_xattr_ibody_set(handle, inode, &i,
1020                                                              &is);
1021                         }
1022                 }
1023         }
1024         if (!error) {
1025                 ext3_xattr_update_super_block(handle, inode->i_sb);
1026                 inode->i_ctime = CURRENT_TIME_SEC;
1027                 error = ext3_mark_iloc_dirty(handle, inode, &is.iloc);
1028                 /*
1029                  * The bh is consumed by ext3_mark_iloc_dirty, even with
1030                  * error != 0.
1031                  */
1032                 is.iloc.bh = NULL;
1033                 if (IS_SYNC(inode))
1034                         handle->h_sync = 1;
1035         }
1036 
1037 cleanup:
1038         brelse(is.iloc.bh);
1039         brelse(bs.bh);
1040         up_write(&EXT3_I(inode)->xattr_sem);
1041         return error;
1042 }
1043 
1044 /*
1045  * ext3_xattr_set()
1046  *
1047  * Like ext3_xattr_set_handle, but start from an inode. This extended
1048  * attribute modification is a filesystem transaction by itself.
1049  *
1050  * Returns 0, or a negative error number on failure.
1051  */
1052 int
1053 ext3_xattr_set(struct inode *inode, int name_index, const char *name,
1054                const void *value, size_t value_len, int flags)
1055 {
1056         handle_t *handle;
1057         int error, retries = 0;
1058 
1059 retry:
1060         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
1061         if (IS_ERR(handle)) {
1062                 error = PTR_ERR(handle);
1063         } else {
1064                 int error2;
1065 
1066                 error = ext3_xattr_set_handle(handle, inode, name_index, name,
1067                                               value, value_len, flags);
1068                 error2 = ext3_journal_stop(handle);
1069                 if (error == -ENOSPC &&
1070                     ext3_should_retry_alloc(inode->i_sb, &retries))
1071                         goto retry;
1072                 if (error == 0)
1073                         error = error2;
1074         }
1075 
1076         return error;
1077 }
1078 
1079 /*
1080  * ext3_xattr_delete_inode()
1081  *
1082  * Free extended attribute resources associated with this inode. This
1083  * is called immediately before an inode is freed. We have exclusive
1084  * access to the inode.
1085  */
1086 void
1087 ext3_xattr_delete_inode(handle_t *handle, struct inode *inode)
1088 {
1089         struct buffer_head *bh = NULL;
1090 
1091         if (!EXT3_I(inode)->i_file_acl)
1092                 goto cleanup;
1093         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
1094         if (!bh) {
1095                 ext3_error(inode->i_sb, __func__,
1096                         "inode %lu: block "E3FSBLK" read error", inode->i_ino,
1097                         EXT3_I(inode)->i_file_acl);
1098                 goto cleanup;
1099         }
1100         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
1101             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1102                 ext3_error(inode->i_sb, __func__,
1103                         "inode %lu: bad block "E3FSBLK, inode->i_ino,
1104                         EXT3_I(inode)->i_file_acl);
1105                 goto cleanup;
1106         }
1107         ext3_xattr_release_block(handle, inode, bh);
1108         EXT3_I(inode)->i_file_acl = 0;
1109 
1110 cleanup:
1111         brelse(bh);
1112 }
1113 
1114 /*
1115  * ext3_xattr_put_super()
1116  *
1117  * This is called when a file system is unmounted.
1118  */
1119 void
1120 ext3_xattr_put_super(struct super_block *sb)
1121 {
1122         mb_cache_shrink(sb->s_bdev);
1123 }
1124 
1125 /*
1126  * ext3_xattr_cache_insert()
1127  *
1128  * Create a new entry in the extended attribute cache, and insert
1129  * it unless such an entry is already in the cache.
1130  *
1131  * Returns 0, or a negative error number on failure.
1132  */
1133 static void
1134 ext3_xattr_cache_insert(struct buffer_head *bh)
1135 {
1136         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1137         struct mb_cache_entry *ce;
1138         int error;
1139 
1140         ce = mb_cache_entry_alloc(ext3_xattr_cache, GFP_NOFS);
1141         if (!ce) {
1142                 ea_bdebug(bh, "out of memory");
1143                 return;
1144         }
1145         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
1146         if (error) {
1147                 mb_cache_entry_free(ce);
1148                 if (error == -EBUSY) {
1149                         ea_bdebug(bh, "already in cache");
1150                         error = 0;
1151                 }
1152         } else {
1153                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1154                 mb_cache_entry_release(ce);
1155         }
1156 }
1157 
1158 /*
1159  * ext3_xattr_cmp()
1160  *
1161  * Compare two extended attribute blocks for equality.
1162  *
1163  * Returns 0 if the blocks are equal, 1 if they differ, and
1164  * a negative error number on errors.
1165  */
1166 static int
1167 ext3_xattr_cmp(struct ext3_xattr_header *header1,
1168                struct ext3_xattr_header *header2)
1169 {
1170         struct ext3_xattr_entry *entry1, *entry2;
1171 
1172         entry1 = ENTRY(header1+1);
1173         entry2 = ENTRY(header2+1);
1174         while (!IS_LAST_ENTRY(entry1)) {
1175                 if (IS_LAST_ENTRY(entry2))
1176                         return 1;
1177                 if (entry1->e_hash != entry2->e_hash ||
1178                     entry1->e_name_index != entry2->e_name_index ||
1179                     entry1->e_name_len != entry2->e_name_len ||
1180                     entry1->e_value_size != entry2->e_value_size ||
1181                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1182                         return 1;
1183                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1184                         return -EIO;
1185                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1186                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1187                            le32_to_cpu(entry1->e_value_size)))
1188                         return 1;
1189 
1190                 entry1 = EXT3_XATTR_NEXT(entry1);
1191                 entry2 = EXT3_XATTR_NEXT(entry2);
1192         }
1193         if (!IS_LAST_ENTRY(entry2))
1194                 return 1;
1195         return 0;
1196 }
1197 
1198 /*
1199  * ext3_xattr_cache_find()
1200  *
1201  * Find an identical extended attribute block.
1202  *
1203  * Returns a pointer to the block found, or NULL if such a block was
1204  * not found or an error occurred.
1205  */
1206 static struct buffer_head *
1207 ext3_xattr_cache_find(struct inode *inode, struct ext3_xattr_header *header,
1208                       struct mb_cache_entry **pce)
1209 {
1210         __u32 hash = le32_to_cpu(header->h_hash);
1211         struct mb_cache_entry *ce;
1212 
1213         if (!header->h_hash)
1214                 return NULL;  /* never share */
1215         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1216 again:
1217         ce = mb_cache_entry_find_first(ext3_xattr_cache, inode->i_sb->s_bdev,
1218                                        hash);
1219         while (ce) {
1220                 struct buffer_head *bh;
1221 
1222                 if (IS_ERR(ce)) {
1223                         if (PTR_ERR(ce) == -EAGAIN)
1224                                 goto again;
1225                         break;
1226                 }
1227                 bh = sb_bread(inode->i_sb, ce->e_block);
1228                 if (!bh) {
1229                         ext3_error(inode->i_sb, __func__,
1230                                 "inode %lu: block %lu read error",
1231                                 inode->i_ino, (unsigned long) ce->e_block);
1232                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1233                                 EXT3_XATTR_REFCOUNT_MAX) {
1234                         ea_idebug(inode, "block %lu refcount %d>=%d",
1235                                   (unsigned long) ce->e_block,
1236                                   le32_to_cpu(BHDR(bh)->h_refcount),
1237                                           EXT3_XATTR_REFCOUNT_MAX);
1238                 } else if (ext3_xattr_cmp(header, BHDR(bh)) == 0) {
1239                         *pce = ce;
1240                         return bh;
1241                 }
1242                 brelse(bh);
1243                 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
1244         }
1245         return NULL;
1246 }
1247 
1248 #define NAME_HASH_SHIFT 5
1249 #define VALUE_HASH_SHIFT 16
1250 
1251 /*
1252  * ext3_xattr_hash_entry()
1253  *
1254  * Compute the hash of an extended attribute.
1255  */
1256 static inline void ext3_xattr_hash_entry(struct ext3_xattr_header *header,
1257                                          struct ext3_xattr_entry *entry)
1258 {
1259         __u32 hash = 0;
1260         char *name = entry->e_name;
1261         int n;
1262 
1263         for (n=0; n < entry->e_name_len; n++) {
1264                 hash = (hash << NAME_HASH_SHIFT) ^
1265                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1266                        *name++;
1267         }
1268 
1269         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1270                 __le32 *value = (__le32 *)((char *)header +
1271                         le16_to_cpu(entry->e_value_offs));
1272                 for (n = (le32_to_cpu(entry->e_value_size) +
1273                      EXT3_XATTR_ROUND) >> EXT3_XATTR_PAD_BITS; n; n--) {
1274                         hash = (hash << VALUE_HASH_SHIFT) ^
1275                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1276                                le32_to_cpu(*value++);
1277                 }
1278         }
1279         entry->e_hash = cpu_to_le32(hash);
1280 }
1281 
1282 #undef NAME_HASH_SHIFT
1283 #undef VALUE_HASH_SHIFT
1284 
1285 #define BLOCK_HASH_SHIFT 16
1286 
1287 /*
1288  * ext3_xattr_rehash()
1289  *
1290  * Re-compute the extended attribute hash value after an entry has changed.
1291  */
1292 static void ext3_xattr_rehash(struct ext3_xattr_header *header,
1293                               struct ext3_xattr_entry *entry)
1294 {
1295         struct ext3_xattr_entry *here;
1296         __u32 hash = 0;
1297 
1298         ext3_xattr_hash_entry(header, entry);
1299         here = ENTRY(header+1);
1300         while (!IS_LAST_ENTRY(here)) {
1301                 if (!here->e_hash) {
1302                         /* Block is not shared if an entry's hash value == 0 */
1303                         hash = 0;
1304                         break;
1305                 }
1306                 hash = (hash << BLOCK_HASH_SHIFT) ^
1307                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1308                        le32_to_cpu(here->e_hash);
1309                 here = EXT3_XATTR_NEXT(here);
1310         }
1311         header->h_hash = cpu_to_le32(hash);
1312 }
1313 
1314 #undef BLOCK_HASH_SHIFT
1315 
1316 int __init
1317 init_ext3_xattr(void)
1318 {
1319         ext3_xattr_cache = mb_cache_create("ext3_xattr", 6);
1320         if (!ext3_xattr_cache)
1321                 return -ENOMEM;
1322         return 0;
1323 }
1324 
1325 void
1326 exit_ext3_xattr(void)
1327 {
1328         if (ext3_xattr_cache)
1329                 mb_cache_destroy(ext3_xattr_cache);
1330         ext3_xattr_cache = NULL;
1331 }
1332 

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