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