fs/ext3/xattr.c

   1 /*
   2  * linux/fs/ext3/xattr.c
   3  *
   4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   5  *
   6  * Fix by Harrison Xing <harrison@mountainviewdata.com>.
   7  * Ext3 code with a lot of help from Eric Jarman <ejarman@acm.org>.
   8  * Extended attributes for symlinks and special files added per
   9  *  suggestion of Luka Renko <luka.renko@hermes.si>.
  10  * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
  11  *  Red Hat Inc.
  12  * ea-in-inode support by Alex Tomas <alex@clusterfs.com> aka bzzz
  13  *  and Andreas Gruenbacher <agruen@suse.de>.
  14  */
  15
  16 /*
  17  * Extended attributes are stored directly in inodes (on file systems with
  18  * inodes bigger than 128 bytes) and on additional disk blocks. The i_file_acl
  19  * field contains the block number if an inode uses an additional block. All
  20  * attributes must fit in the inode and one additional block. Blocks that
  21  * contain the identical set of attributes may be shared among several inodes.
  22  * Identical blocks are detected by keeping a cache of blocks that have
  23  * recently been accessed.
  24  *
  25  * The attributes in inodes and on blocks have a different header; the entries
  26  * are stored in the same format:
  27  *
  28  *   +------------------+
  29  *   | header           |
  30  *   | entry 1          | |
  31  *   | entry 2          | | growing downwards
  32  *   | entry 3          | v
  33  *   | four null bytes  |
  34  *   | . . .            |
  35  *   | value 1          | ^
  36  *   | value 3          | | growing upwards
  37  *   | value 2          | |
  38  *   +------------------+
  39  *
  40  * The header is followed by multiple entry descriptors. In disk blocks, the
  41  * entry descriptors are kept sorted. In inodes, they are unsorted. The
  42  * attribute values are aligned to the end of the block in no specific order.
  43  *
  44  * Locking strategy
  45  * ----------------
  46  * EXT3_I(inode)->i_file_acl is protected by EXT3_I(inode)->xattr_sem.
  47  * EA blocks are only changed if they are exclusive to an inode, so
  48  * holding xattr_sem also means that nothing but the EA block's reference
  49  * count can change. Multiple writers to the same block are synchronized
  50  * by the buffer lock.
  51  */
  52
  53 #include "ext3.h"
  54 #include <linux/mbcache.h>
  55 #include <linux/quotaops.h>
  56 #include "xattr.h"
  57 #include "acl.h"
  58
  59 #define BHDR(bh) ((struct ext3_xattr_header *)((bh)->b_data))
  60 #define ENTRY(ptr) ((struct ext3_xattr_entry *)(ptr))
  61 #define BFIRST(bh) ENTRY(BHDR(bh)+1)
  62 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
  63
  64 #define IHDR(inode, raw_inode) \
  65         ((struct ext3_xattr_ibody_header *) \
  66                 ((void *)raw_inode + \
  67                  EXT3_GOOD_OLD_INODE_SIZE + \
  68                  EXT3_I(inode)->i_extra_isize))
  69 #define IFIRST(hdr) ((struct ext3_xattr_entry *)((hdr)+1))
  70
  71 #ifdef EXT3_XATTR_DEBUG
  72 # define ea_idebug(inode, f...) do { \
  73                 printk(KERN_DEBUG "inode %s:%lu: ", \
  74                         inode->i_sb->s_id, inode->i_ino); \
  75                 printk(f); \
  76                 printk("\n"); \
  77         } while (0)
  78 # define ea_bdebug(bh, f...) do { \
  79                 char b[BDEVNAME_SIZE]; \
  80                 printk(KERN_DEBUG "block %s:%lu: ", \
  81                         bdevname(bh->b_bdev, b), \
  82                         (unsigned long) bh->b_blocknr); \
  83                 printk(f); \
  84                 printk("\n"); \
  85         } while (0)
  86 #else
  87 # define ea_idebug(f...)
  88 # define ea_bdebug(f...)
  89 #endif
  90
  91 static void ext3_xattr_cache_insert(struct buffer_head *);
  92 static struct buffer_head *ext3_xattr_cache_find(struct inode *,
  93                                                  struct ext3_xattr_header *,
  94                                                  struct mb_cache_entry **);
  95 static void ext3_xattr_rehash(struct ext3_xattr_header *,
  96                               struct ext3_xattr_entry *);
  97 static int ext3_xattr_list(struct dentry *dentry, char *buffer,
  98                            size_t buffer_size);
  99
 100 static struct mb_cache *ext3_xattr_cache;
 101
 102 static const struct xattr_handler *ext3_xattr_handler_map[] = {
 103         [EXT3_XATTR_INDEX_USER]              = &ext3_xattr_user_handler,
 104 #ifdef CONFIG_EXT3_FS_POSIX_ACL
 105         [EXT3_XATTR_INDEX_POSIX_ACL_ACCESS]  = &posix_acl_access_xattr_handler,
 106         [EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
 107 #endif
 108         [EXT3_XATTR_INDEX_TRUSTED]           = &ext3_xattr_trusted_handler,
 109 #ifdef CONFIG_EXT3_FS_SECURITY
 110         [EXT3_XATTR_INDEX_SECURITY]          = &ext3_xattr_security_handler,
 111 #endif
 112 };
 113
 114 const struct xattr_handler *ext3_xattr_handlers[] = {
 115         &ext3_xattr_user_handler,
 116         &ext3_xattr_trusted_handler,
 117 #ifdef CONFIG_EXT3_FS_POSIX_ACL
 118         &posix_acl_access_xattr_handler,
 119         &posix_acl_default_xattr_handler,
 120 #endif
 121 #ifdef CONFIG_EXT3_FS_SECURITY
 122         &ext3_xattr_security_handler,
 123 #endif
 124         NULL
 125 };
 126
 127 static inline const struct xattr_handler *
 128 ext3_xattr_handler(int name_index)
 129 {
 130         const struct xattr_handler *handler = NULL;
 131
 132         if (name_index > 0 && name_index < ARRAY_SIZE(ext3_xattr_handler_map))
 133                 handler = ext3_xattr_handler_map[name_index];
 134         return handler;
 135 }
 136
 137 /*
 138  * Inode operation listxattr()
 139  *
 140  * d_inode(dentry)->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 = d_inode(dentry);
 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 = d_inode(dentry);
 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(d_inode(dentry))->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(d_inode(dentry))->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_LEN(name_len) +
 550                            EXT3_XATTR_SIZE(i->value_len))
 551                         return -ENOSPC;
 552         }
 553
 554         if (i->value && s->not_found) {
 555                 /* Insert the new name. */
 556                 size_t size = EXT3_XATTR_LEN(name_len);
 557                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
 558                 memmove((void *)s->here + size, s->here, rest);
 559                 memset(s->here, 0, size);
 560                 s->here->e_name_index = i->name_index;
 561                 s->here->e_name_len = name_len;
 562                 memcpy(s->here->e_name, i->name, name_len);
 563         } else {
 564                 if (!s->here->e_value_block && s->here->e_value_size) {
 565                         void *first_val = s->base + min_offs;
 566                         size_t offs = le16_to_cpu(s->here->e_value_offs);
 567                         void *val = s->base + offs;
 568                         size_t size = EXT3_XATTR_SIZE(
 569                                 le32_to_cpu(s->here->e_value_size));
 570
 571                         if (i->value && size == EXT3_XATTR_SIZE(i->value_len)) {
 572                                 /* The old and the new value have the same
 573                                    size. Just replace. */
 574                                 s->here->e_value_size =
 575                                         cpu_to_le32(i->value_len);
 576                                 memset(val + size - EXT3_XATTR_PAD, 0,
 577                                        EXT3_XATTR_PAD); /* Clear pad bytes. */
 578                                 memcpy(val, i->value, i->value_len);
 579                                 return 0;
 580                         }
 581
 582                         /* Remove the old value. */
 583                         memmove(first_val + size, first_val, val - first_val);
 584                         memset(first_val, 0, size);
 585                         s->here->e_value_size = 0;
 586                         s->here->e_value_offs = 0;
 587                         min_offs += size;
 588
 589                         /* Adjust all value offsets. */
 590                         last = s->first;
 591                         while (!IS_LAST_ENTRY(last)) {
 592                                 size_t o = le16_to_cpu(last->e_value_offs);
 593                                 if (!last->e_value_block &&
 594                                     last->e_value_size && o < offs)
 595                                         last->e_value_offs =
 596                                                 cpu_to_le16(o + size);
 597                                 last = EXT3_XATTR_NEXT(last);
 598                         }
 599                 }
 600                 if (!i->value) {
 601                         /* Remove the old name. */
 602                         size_t size = EXT3_XATTR_LEN(name_len);
 603                         last = ENTRY((void *)last - size);
 604                         memmove(s->here, (void *)s->here + size,
 605                                 (void *)last - (void *)s->here + sizeof(__u32));
 606                         memset(last, 0, size);
 607                 }
 608         }
 609
 610         if (i->value) {
 611                 /* Insert the new value. */
 612                 s->here->e_value_size = cpu_to_le32(i->value_len);
 613                 if (i->value_len) {
 614                         size_t size = EXT3_XATTR_SIZE(i->value_len);
 615                         void *val = s->base + min_offs - size;
 616                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
 617                         memset(val + size - EXT3_XATTR_PAD, 0,
 618                                EXT3_XATTR_PAD); /* Clear the pad bytes. */
 619                         memcpy(val, i->value, i->value_len);
 620                 }
 621         }
 622         return 0;
 623 }
 624
 625 struct ext3_xattr_block_find {
 626         struct ext3_xattr_search s;
 627         struct buffer_head *bh;
 628 };
 629
 630 static int
 631 ext3_xattr_block_find(struct inode *inode, struct ext3_xattr_info *i,
 632                       struct ext3_xattr_block_find *bs)
 633 {
 634         struct super_block *sb = inode->i_sb;
 635         int error;
 636
 637         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
 638                   i->name_index, i->name, i->value, (long)i->value_len);
 639
 640         if (EXT3_I(inode)->i_file_acl) {
 641                 /* The inode already has an extended attribute block. */
 642                 bs->bh = sb_bread(sb, EXT3_I(inode)->i_file_acl);
 643                 error = -EIO;
 644                 if (!bs->bh)
 645                         goto cleanup;
 646                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
 647                         atomic_read(&(bs->bh->b_count)),
 648                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
 649                 if (ext3_xattr_check_block(bs->bh)) {
 650                         ext3_error(sb, __func__,
 651                                 "inode %lu: bad block "E3FSBLK, inode->i_ino,
 652                                 EXT3_I(inode)->i_file_acl);
 653                         error = -EIO;
 654                         goto cleanup;
 655                 }
 656                 /* Find the named attribute. */
 657                 bs->s.base = BHDR(bs->bh);
 658                 bs->s.first = BFIRST(bs->bh);
 659                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
 660                 bs->s.here = bs->s.first;
 661                 error = ext3_xattr_find_entry(&bs->s.here, i->name_index,
 662                                               i->name, bs->bh->b_size, 1);
 663                 if (error && error != -ENODATA)
 664                         goto cleanup;
 665                 bs->s.not_found = error;
 666         }
 667         error = 0;
 668
 669 cleanup:
 670         return error;
 671 }
 672
 673 static int
 674 ext3_xattr_block_set(handle_t *handle, struct inode *inode,
 675                      struct ext3_xattr_info *i,
 676                      struct ext3_xattr_block_find *bs)
 677 {
 678         struct super_block *sb = inode->i_sb;
 679         struct buffer_head *new_bh = NULL;
 680         struct ext3_xattr_search *s = &bs->s;
 681         struct mb_cache_entry *ce = NULL;
 682         int error = 0;
 683
 684 #define header(x) ((struct ext3_xattr_header *)(x))
 685
 686         if (i->value && i->value_len > sb->s_blocksize)
 687                 return -ENOSPC;
 688         if (s->base) {
 689                 ce = mb_cache_entry_get(ext3_xattr_cache, bs->bh->b_bdev,
 690                                         bs->bh->b_blocknr);
 691                 error = ext3_journal_get_write_access(handle, bs->bh);
 692                 if (error)
 693                         goto cleanup;
 694                 lock_buffer(bs->bh);
 695
 696                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 697                         if (ce) {
 698                                 mb_cache_entry_free(ce);
 699                                 ce = NULL;
 700                         }
 701                         ea_bdebug(bs->bh, "modifying in-place");
 702                         error = ext3_xattr_set_entry(i, s);
 703                         if (!error) {
 704                                 if (!IS_LAST_ENTRY(s->first))
 705                                         ext3_xattr_rehash(header(s->base),
 706                                                           s->here);
 707                                 ext3_xattr_cache_insert(bs->bh);
 708                         }
 709                         unlock_buffer(bs->bh);
 710                         if (error == -EIO)
 711                                 goto bad_block;
 712                         if (!error)
 713                                 error = ext3_journal_dirty_metadata(handle,
 714                                                                     bs->bh);
 715                         if (error)
 716                                 goto cleanup;
 717                         goto inserted;
 718                 } else {
 719                         int offset = (char *)s->here - bs->bh->b_data;
 720
 721                         unlock_buffer(bs->bh);
 722                         journal_release_buffer(handle, bs->bh);
 723
 724                         if (ce) {
 725                                 mb_cache_entry_release(ce);
 726                                 ce = NULL;
 727                         }
 728                         ea_bdebug(bs->bh, "cloning");
 729                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
 730                         error = -ENOMEM;
 731                         if (s->base == NULL)
 732                                 goto cleanup;
 733                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 734                         s->first = ENTRY(header(s->base)+1);
 735                         header(s->base)->h_refcount = cpu_to_le32(1);
 736                         s->here = ENTRY(s->base + offset);
 737                         s->end = s->base + bs->bh->b_size;
 738                 }
 739         } else {
 740                 /* Allocate a buffer where we construct the new block. */
 741                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
 742                 /* assert(header == s->base) */
 743                 error = -ENOMEM;
 744                 if (s->base == NULL)
 745                         goto cleanup;
 746                 header(s->base)->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
 747                 header(s->base)->h_blocks = cpu_to_le32(1);
 748                 header(s->base)->h_refcount = cpu_to_le32(1);
 749                 s->first = ENTRY(header(s->base)+1);
 750                 s->here = ENTRY(header(s->base)+1);
 751                 s->end = s->base + sb->s_blocksize;
 752         }
 753
 754         error = ext3_xattr_set_entry(i, s);
 755         if (error == -EIO)
 756                 goto bad_block;
 757         if (error)
 758                 goto cleanup;
 759         if (!IS_LAST_ENTRY(s->first))
 760                 ext3_xattr_rehash(header(s->base), s->here);
 761
 762 inserted:
 763         if (!IS_LAST_ENTRY(s->first)) {
 764                 new_bh = ext3_xattr_cache_find(inode, header(s->base), &ce);
 765                 if (new_bh) {
 766                         /* We found an identical block in the cache. */
 767                         if (new_bh == bs->bh)
 768                                 ea_bdebug(new_bh, "keeping");
 769                         else {
 770                                 /* The old block is released after updating
 771                                    the inode. */
 772                                 error = dquot_alloc_block(inode, 1);
 773                                 if (error)
 774                                         goto cleanup;
 775                                 error = ext3_journal_get_write_access(handle,
 776                                                                       new_bh);
 777                                 if (error)
 778                                         goto cleanup_dquot;
 779                                 lock_buffer(new_bh);
 780                                 le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
 781                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
 782                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 783                                 unlock_buffer(new_bh);
 784                                 error = ext3_journal_dirty_metadata(handle,
 785                                                                     new_bh);
 786                                 if (error)
 787                                         goto cleanup_dquot;
 788                         }
 789                         mb_cache_entry_release(ce);
 790                         ce = NULL;
 791                 } else if (bs->bh && s->base == bs->bh->b_data) {
 792                         /* We were modifying this block in-place. */
 793                         ea_bdebug(bs->bh, "keeping this block");
 794                         new_bh = bs->bh;
 795                         get_bh(new_bh);
 796                 } else {
 797                         /* We need to allocate a new block */
 798                         ext3_fsblk_t goal = ext3_group_first_block_no(sb,
 799                                                 EXT3_I(inode)->i_block_group);
 800                         ext3_fsblk_t block;
 801
 802                         /*
 803                          * Protect us agaist concurrent allocations to the
 804                          * same inode from ext3_..._writepage(). Reservation
 805                          * code does not expect racing allocations.
 806                          */
 807                         mutex_lock(&EXT3_I(inode)->truncate_mutex);
 808                         block = ext3_new_block(handle, inode, goal, &error);
 809                         mutex_unlock(&EXT3_I(inode)->truncate_mutex);
 810                         if (error)
 811                                 goto cleanup;
 812                         ea_idebug(inode, "creating block %d", block);
 813
 814                         new_bh = sb_getblk(sb, block);
 815                         if (unlikely(!new_bh)) {
 816 getblk_failed:
 817                                 ext3_free_blocks(handle, inode, block, 1);
 818                                 error = -ENOMEM;
 819                                 goto cleanup;
 820                         }
 821                         lock_buffer(new_bh);
 822                         error = ext3_journal_get_create_access(handle, new_bh);
 823                         if (error) {
 824                                 unlock_buffer(new_bh);
 825                                 goto getblk_failed;
 826                         }
 827                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
 828                         set_buffer_uptodate(new_bh);
 829                         unlock_buffer(new_bh);
 830                         ext3_xattr_cache_insert(new_bh);
 831                         error = ext3_journal_dirty_metadata(handle, new_bh);
 832                         if (error)
 833                                 goto cleanup;
 834                 }
 835         }
 836
 837         /* Update the inode. */
 838         EXT3_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
 839
 840         /* Drop the previous xattr block. */
 841         if (bs->bh && bs->bh != new_bh)
 842                 ext3_xattr_release_block(handle, inode, bs->bh);
 843         error = 0;
 844
 845 cleanup:
 846         if (ce)
 847                 mb_cache_entry_release(ce);
 848         brelse(new_bh);
 849         if (!(bs->bh && s->base == bs->bh->b_data))
 850                 kfree(s->base);
 851
 852         return error;
 853
 854 cleanup_dquot:
 855         dquot_free_block(inode, 1);
 856         goto cleanup;
 857
 858 bad_block:
 859         ext3_error(inode->i_sb, __func__,
 860                    "inode %lu: bad block "E3FSBLK, inode->i_ino,
 861                    EXT3_I(inode)->i_file_acl);
 862         goto cleanup;
 863
 864 #undef header
 865 }
 866
 867 struct ext3_xattr_ibody_find {
 868         struct ext3_xattr_search s;
 869         struct ext3_iloc iloc;
 870 };
 871
 872 static int
 873 ext3_xattr_ibody_find(struct inode *inode, struct ext3_xattr_info *i,
 874                       struct ext3_xattr_ibody_find *is)
 875 {
 876         struct ext3_xattr_ibody_header *header;
 877         struct ext3_inode *raw_inode;
 878         int error;
 879
 880         if (EXT3_I(inode)->i_extra_isize == 0)
 881                 return 0;
 882         raw_inode = ext3_raw_inode(&is->iloc);
 883         header = IHDR(inode, raw_inode);
 884         is->s.base = is->s.first = IFIRST(header);
 885         is->s.here = is->s.first;
 886         is->s.end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 887         if (ext3_test_inode_state(inode, EXT3_STATE_XATTR)) {
 888                 error = ext3_xattr_check_names(IFIRST(header), is->s.end);
 889                 if (error)
 890                         return error;
 891                 /* Find the named attribute. */
 892                 error = ext3_xattr_find_entry(&is->s.here, i->name_index,
 893                                               i->name, is->s.end -
 894                                               (void *)is->s.base, 0);
 895                 if (error && error != -ENODATA)
 896                         return error;
 897                 is->s.not_found = error;
 898         }
 899         return 0;
 900 }
 901
 902 static int
 903 ext3_xattr_ibody_set(handle_t *handle, struct inode *inode,
 904                      struct ext3_xattr_info *i,
 905                      struct ext3_xattr_ibody_find *is)
 906 {
 907         struct ext3_xattr_ibody_header *header;
 908         struct ext3_xattr_search *s = &is->s;
 909         int error;
 910
 911         if (EXT3_I(inode)->i_extra_isize == 0)
 912                 return -ENOSPC;
 913         error = ext3_xattr_set_entry(i, s);
 914         if (error)
 915                 return error;
 916         header = IHDR(inode, ext3_raw_inode(&is->iloc));
 917         if (!IS_LAST_ENTRY(s->first)) {
 918                 header->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
 919                 ext3_set_inode_state(inode, EXT3_STATE_XATTR);
 920         } else {
 921                 header->h_magic = cpu_to_le32(0);
 922                 ext3_clear_inode_state(inode, EXT3_STATE_XATTR);
 923         }
 924         return 0;
 925 }
 926
 927 /*
 928  * ext3_xattr_set_handle()
 929  *
 930  * Create, replace or remove an extended attribute for this inode.  Value
 931  * is NULL to remove an existing extended attribute, and non-NULL to
 932  * either replace an existing extended attribute, or create a new extended
 933  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 934  * specify that an extended attribute must exist and must not exist
 935  * previous to the call, respectively.
 936  *
 937  * Returns 0, or a negative error number on failure.
 938  */
 939 int
 940 ext3_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
 941                       const char *name, const void *value, size_t value_len,
 942                       int flags)
 943 {
 944         struct ext3_xattr_info i = {
 945                 .name_index = name_index,
 946                 .name = name,
 947                 .value = value,
 948                 .value_len = value_len,
 949
 950         };
 951         struct ext3_xattr_ibody_find is = {
 952                 .s = { .not_found = -ENODATA, },
 953         };
 954         struct ext3_xattr_block_find bs = {
 955                 .s = { .not_found = -ENODATA, },
 956         };
 957         int error;
 958
 959         if (!name)
 960                 return -EINVAL;
 961         if (strlen(name) > 255)
 962                 return -ERANGE;
 963         down_write(&EXT3_I(inode)->xattr_sem);
 964         error = ext3_get_inode_loc(inode, &is.iloc);
 965         if (error)
 966                 goto cleanup;
 967
 968         error = ext3_journal_get_write_access(handle, is.iloc.bh);
 969         if (error)
 970                 goto cleanup;
 971
 972         if (ext3_test_inode_state(inode, EXT3_STATE_NEW)) {
 973                 struct ext3_inode *raw_inode = ext3_raw_inode(&is.iloc);
 974                 memset(raw_inode, 0, EXT3_SB(inode->i_sb)->s_inode_size);
 975                 ext3_clear_inode_state(inode, EXT3_STATE_NEW);
 976         }
 977
 978         error = ext3_xattr_ibody_find(inode, &i, &is);
 979         if (error)
 980                 goto cleanup;
 981         if (is.s.not_found)
 982                 error = ext3_xattr_block_find(inode, &i, &bs);
 983         if (error)
 984                 goto cleanup;
 985         if (is.s.not_found && bs.s.not_found) {
 986                 error = -ENODATA;
 987                 if (flags & XATTR_REPLACE)
 988                         goto cleanup;
 989                 error = 0;
 990                 if (!value)
 991                         goto cleanup;
 992         } else {
 993                 error = -EEXIST;
 994                 if (flags & XATTR_CREATE)
 995                         goto cleanup;
 996         }
 997         if (!value) {
 998                 if (!is.s.not_found)
 999                         error = ext3_xattr_ibody_set(handle, inode, &i, &is);
1000                 else if (!bs.s.not_found)
1001                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1002         } else {
1003                 error = ext3_xattr_ibody_set(handle, inode, &i, &is);
1004                 if (!error && !bs.s.not_found) {
1005                         i.value = NULL;
1006                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1007                 } else if (error == -ENOSPC) {
1008                         if (EXT3_I(inode)->i_file_acl && !bs.s.base) {
1009                                 error = ext3_xattr_block_find(inode, &i, &bs);
1010                                 if (error)
1011                                         goto cleanup;
1012                         }
1013                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1014                         if (error)
1015                                 goto cleanup;
1016                         if (!is.s.not_found) {
1017                                 i.value = NULL;
1018                                 error = ext3_xattr_ibody_set(handle, inode, &i,
1019                                                              &is);
1020                         }
1021                 }
1022         }
1023         if (!error) {
1024                 ext3_xattr_update_super_block(handle, inode->i_sb);
1025                 inode->i_ctime = CURRENT_TIME_SEC;
1026                 error = ext3_mark_iloc_dirty(handle, inode, &is.iloc);
1027                 /*
1028                  * The bh is consumed by ext3_mark_iloc_dirty, even with
1029                  * error != 0.
1030                  */
1031                 is.iloc.bh = NULL;
1032                 if (IS_SYNC(inode))
1033                         handle->h_sync = 1;
1034         }
1035
1036 cleanup:
1037         brelse(is.iloc.bh);
1038         brelse(bs.bh);
1039         up_write(&EXT3_I(inode)->xattr_sem);
1040         return error;
1041 }
1042
1043 /*
1044  * ext3_xattr_set()
1045  *
1046  * Like ext3_xattr_set_handle, but start from an inode. This extended
1047  * attribute modification is a filesystem transaction by itself.
1048  *
1049  * Returns 0, or a negative error number on failure.
1050  */
1051 int
1052 ext3_xattr_set(struct inode *inode, int name_index, const char *name,
1053                const void *value, size_t value_len, int flags)
1054 {
1055         handle_t *handle;
1056         int error, retries = 0;
1057
1058 retry:
1059         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
1060         if (IS_ERR(handle)) {
1061                 error = PTR_ERR(handle);
1062         } else {
1063                 int error2;
1064
1065                 error = ext3_xattr_set_handle(handle, inode, name_index, name,
1066                                               value, value_len, flags);
1067                 error2 = ext3_journal_stop(handle);
1068                 if (error == -ENOSPC &&
1069                     ext3_should_retry_alloc(inode->i_sb, &retries))
1070                         goto retry;
1071                 if (error == 0)
1072                         error = error2;
1073         }
1074
1075         return error;
1076 }
1077
1078 /*
1079  * ext3_xattr_delete_inode()
1080  *
1081  * Free extended attribute resources associated with this inode. This
1082  * is called immediately before an inode is freed. We have exclusive
1083  * access to the inode.
1084  */
1085 void
1086 ext3_xattr_delete_inode(handle_t *handle, struct inode *inode)
1087 {
1088         struct buffer_head *bh = NULL;
1089
1090         if (!EXT3_I(inode)->i_file_acl)
1091                 goto cleanup;
1092         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
1093         if (!bh) {
1094                 ext3_error(inode->i_sb, __func__,
1095                         "inode %lu: block "E3FSBLK" read error", inode->i_ino,
1096                         EXT3_I(inode)->i_file_acl);
1097                 goto cleanup;
1098         }
1099         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
1100             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1101                 ext3_error(inode->i_sb, __func__,
1102                         "inode %lu: bad block "E3FSBLK, inode->i_ino,
1103                         EXT3_I(inode)->i_file_acl);
1104                 goto cleanup;
1105         }
1106         ext3_xattr_release_block(handle, inode, bh);
1107         EXT3_I(inode)->i_file_acl = 0;
1108
1109 cleanup:
1110         brelse(bh);
1111 }
1112
1113 /*
1114  * ext3_xattr_put_super()
1115  *
1116  * This is called when a file system is unmounted.
1117  */
1118 void
1119 ext3_xattr_put_super(struct super_block *sb)
1120 {
1121         mb_cache_shrink(sb->s_bdev);
1122 }
1123
1124 /*
1125  * ext3_xattr_cache_insert()
1126  *
1127  * Create a new entry in the extended attribute cache, and insert
1128  * it unless such an entry is already in the cache.
1129  *
1130  * Returns 0, or a negative error number on failure.
1131  */
1132 static void
1133 ext3_xattr_cache_insert(struct buffer_head *bh)
1134 {
1135         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1136         struct mb_cache_entry *ce;
1137         int error;
1138
1139         ce = mb_cache_entry_alloc(ext3_xattr_cache, GFP_NOFS);
1140         if (!ce) {
1141                 ea_bdebug(bh, "out of memory");
1142                 return;
1143         }
1144         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
1145         if (error) {
1146                 mb_cache_entry_free(ce);
1147                 if (error == -EBUSY) {
1148                         ea_bdebug(bh, "already in cache");
1149                         error = 0;
1150                 }
1151         } else {
1152                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1153                 mb_cache_entry_release(ce);
1154         }
1155 }
1156
1157 /*
1158  * ext3_xattr_cmp()
1159  *
1160  * Compare two extended attribute blocks for equality.
1161  *
1162  * Returns 0 if the blocks are equal, 1 if they differ, and
1163  * a negative error number on errors.
1164  */
1165 static int
1166 ext3_xattr_cmp(struct ext3_xattr_header *header1,
1167                struct ext3_xattr_header *header2)
1168 {
1169         struct ext3_xattr_entry *entry1, *entry2;
1170
1171         entry1 = ENTRY(header1+1);
1172         entry2 = ENTRY(header2+1);
1173         while (!IS_LAST_ENTRY(entry1)) {
1174                 if (IS_LAST_ENTRY(entry2))
1175                         return 1;
1176                 if (entry1->e_hash != entry2->e_hash ||
1177                     entry1->e_name_index != entry2->e_name_index ||
1178                     entry1->e_name_len != entry2->e_name_len ||
1179                     entry1->e_value_size != entry2->e_value_size ||
1180                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1181                         return 1;
1182                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1183                         return -EIO;
1184                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1185                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1186                            le32_to_cpu(entry1->e_value_size)))
1187                         return 1;
1188
1189                 entry1 = EXT3_XATTR_NEXT(entry1);
1190                 entry2 = EXT3_XATTR_NEXT(entry2);
1191         }
1192         if (!IS_LAST_ENTRY(entry2))
1193                 return 1;
1194         return 0;
1195 }
1196
1197 /*
1198  * ext3_xattr_cache_find()
1199  *
1200  * Find an identical extended attribute block.
1201  *
1202  * Returns a pointer to the block found, or NULL if such a block was
1203  * not found or an error occurred.
1204  */
1205 static struct buffer_head *
1206 ext3_xattr_cache_find(struct inode *inode, struct ext3_xattr_header *header,
1207                       struct mb_cache_entry **pce)
1208 {
1209         __u32 hash = le32_to_cpu(header->h_hash);
1210         struct mb_cache_entry *ce;
1211
1212         if (!header->h_hash)
1213                 return NULL;  /* never share */
1214         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1215 again:
1216         ce = mb_cache_entry_find_first(ext3_xattr_cache, inode->i_sb->s_bdev,
1217                                        hash);
1218         while (ce) {
1219                 struct buffer_head *bh;
1220
1221                 if (IS_ERR(ce)) {
1222                         if (PTR_ERR(ce) == -EAGAIN)
1223                                 goto again;
1224                         break;
1225                 }
1226                 bh = sb_bread(inode->i_sb, ce->e_block);
1227                 if (!bh) {
1228                         ext3_error(inode->i_sb, __func__,
1229                                 "inode %lu: block %lu read error",
1230                                 inode->i_ino, (unsigned long) ce->e_block);
1231                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1232                                 EXT3_XATTR_REFCOUNT_MAX) {
1233                         ea_idebug(inode, "block %lu refcount %d>=%d",
1234                                   (unsigned long) ce->e_block,
1235                                   le32_to_cpu(BHDR(bh)->h_refcount),
1236                                           EXT3_XATTR_REFCOUNT_MAX);
1237                 } else if (ext3_xattr_cmp(header, BHDR(bh)) == 0) {
1238                         *pce = ce;
1239                         return bh;
1240                 }
1241                 brelse(bh);
1242                 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
1243         }
1244         return NULL;
1245 }
1246
1247 #define NAME_HASH_SHIFT 5
1248 #define VALUE_HASH_SHIFT 16
1249
1250 /*
1251  * ext3_xattr_hash_entry()
1252  *
1253  * Compute the hash of an extended attribute.
1254  */
1255 static inline void ext3_xattr_hash_entry(struct ext3_xattr_header *header,
1256                                          struct ext3_xattr_entry *entry)
1257 {
1258         __u32 hash = 0;
1259         char *name = entry->e_name;
1260         int n;
1261
1262         for (n=0; n < entry->e_name_len; n++) {
1263                 hash = (hash << NAME_HASH_SHIFT) ^
1264                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1265                        *name++;
1266         }
1267
1268         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1269                 __le32 *value = (__le32 *)((char *)header +
1270                         le16_to_cpu(entry->e_value_offs));
1271                 for (n = (le32_to_cpu(entry->e_value_size) +
1272                      EXT3_XATTR_ROUND) >> EXT3_XATTR_PAD_BITS; n; n--) {
1273                         hash = (hash << VALUE_HASH_SHIFT) ^
1274                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1275                                le32_to_cpu(*value++);
1276                 }
1277         }
1278         entry->e_hash = cpu_to_le32(hash);
1279 }
1280
1281 #undef NAME_HASH_SHIFT
1282 #undef VALUE_HASH_SHIFT
1283
1284 #define BLOCK_HASH_SHIFT 16
1285
1286 /*
1287  * ext3_xattr_rehash()
1288  *
1289  * Re-compute the extended attribute hash value after an entry has changed.
1290  */
1291 static void ext3_xattr_rehash(struct ext3_xattr_header *header,
1292                               struct ext3_xattr_entry *entry)
1293 {
1294         struct ext3_xattr_entry *here;
1295         __u32 hash = 0;
1296
1297         ext3_xattr_hash_entry(header, entry);
1298         here = ENTRY(header+1);
1299         while (!IS_LAST_ENTRY(here)) {
1300                 if (!here->e_hash) {
1301                         /* Block is not shared if an entry's hash value == 0 */
1302                         hash = 0;
1303                         break;
1304                 }
1305                 hash = (hash << BLOCK_HASH_SHIFT) ^
1306                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1307                        le32_to_cpu(here->e_hash);
1308                 here = EXT3_XATTR_NEXT(here);
1309         }
1310         header->h_hash = cpu_to_le32(hash);
1311 }
1312
1313 #undef BLOCK_HASH_SHIFT
1314
1315 int __init
1316 init_ext3_xattr(void)
1317 {
1318         ext3_xattr_cache = mb_cache_create("ext3_xattr", 6);
1319         if (!ext3_xattr_cache)
1320                 return -ENOMEM;
1321         return 0;
1322 }
1323
1324 void
1325 exit_ext3_xattr(void)
1326 {
1327         if (ext3_xattr_cache)
1328                 mb_cache_destroy(ext3_xattr_cache);
1329         ext3_xattr_cache = NULL;
1330 }