fs/ext3/xattr.c

   1 /*
   2  * linux/fs/ext3/xattr.c
   3  *
   4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <[email protected]>
   5  *
   6  * Fix by Harrison Xing <[email protected]>.
   7  * Ext3 code with a lot of help from Eric Jarman <[email protected]>.
   8  * Extended attributes for symlinks and special files added per
   9  *  suggestion of Luka Renko <[email protected]>.
  10  * xattr consolidation Copyright (c) 2004 James Morris <[email protected]>,
  11  *  Red Hat Inc.
  12  * ea-in-inode support by Alex Tomas <[email protected]> aka bzzz
  13  *  and Andreas Gruenbacher <[email protected]>.
  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]  = &ext3_xattr_acl_access_handler,
 106         [EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext3_xattr_acl_default_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         &ext3_xattr_acl_access_handler,
 119         &ext3_xattr_acl_default_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 (!new_bh) {
 817 getblk_failed:
 818                                 ext3_free_blocks(handle, inode, block, 1);
 819                                 error = -EIO;
 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 }