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   1 /*
   2  * linux/fs/ext3/xattr.c
   3  *
   4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   5  *
   6  * Fix by Harrison Xing <harrison@mountainviewdata.com>.
   7  * Ext3 code with a lot of help from Eric Jarman <ejarman@acm.org>.
   8  * Extended attributes for symlinks and special files added per
   9  *  suggestion of Luka Renko <luka.renko@hermes.si>.
  10  * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
  11  *  Red Hat Inc.
  12  * ea-in-inode support by Alex Tomas <alex@clusterfs.com> aka bzzz
  13  *  and Andreas Gruenbacher <agruen@suse.de>.
  14  */
  15
  16 /*
  17  * Extended attributes are stored directly in inodes (on file systems with
  18  * inodes bigger than 128 bytes) and on additional disk blocks. The i_file_acl
  19  * field contains the block number if an inode uses an additional block. All
  20  * attributes must fit in the inode and one additional block. Blocks that
  21  * contain the identical set of attributes may be shared among several inodes.
  22  * Identical blocks are detected by keeping a cache of blocks that have
  23  * recently been accessed.
  24  *
  25  * The attributes in inodes and on blocks have a different header; the entries
  26  * are stored in the same format:
  27  *
  28  *   +------------------+
  29  *   | header           |
  30  *   | entry 1          | |
  31  *   | entry 2          | | growing downwards
  32  *   | entry 3          | v
  33  *   | four null bytes  |
  34  *   | . . .            |
  35  *   | value 1          | ^
  36  *   | value 3          | | growing upwards
  37  *   | value 2          | |
  38  *   +------------------+
  39  *
  40  * The header is followed by multiple entry descriptors. In disk blocks, the
  41  * entry descriptors are kept sorted. In inodes, they are unsorted. The
  42  * attribute values are aligned to the end of the block in no specific order.
  43  *
  44  * Locking strategy
  45  * ----------------
  46  * EXT3_I(inode)->i_file_acl is protected by EXT3_I(inode)->xattr_sem.
  47  * EA blocks are only changed if they are exclusive to an inode, so
  48  * holding xattr_sem also means that nothing but the EA block's reference
  49  * count can change. Multiple writers to the same block are synchronized
  50  * by the buffer lock.
  51  */
  52
  53 #include <linux/init.h>
  54 #include <linux/fs.h>
  55 #include <linux/slab.h>
  56 #include <linux/ext3_jbd.h>
  57 #include <linux/ext3_fs.h>
  58 #include <linux/mbcache.h>
  59 #include <linux/quotaops.h>
  60 #include <linux/rwsem.h>
  61 #include "xattr.h"
  62 #include "acl.h"
  63
  64 #define BHDR(bh) ((struct ext3_xattr_header *)((bh)->b_data))
  65 #define ENTRY(ptr) ((struct ext3_xattr_entry *)(ptr))
  66 #define BFIRST(bh) ENTRY(BHDR(bh)+1)
  67 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
  68
  69 #define IHDR(inode, raw_inode) \
  70         ((struct ext3_xattr_ibody_header *) \
  71                 ((void *)raw_inode + \
  72                  EXT3_GOOD_OLD_INODE_SIZE + \
  73                  EXT3_I(inode)->i_extra_isize))
  74 #define IFIRST(hdr) ((struct ext3_xattr_entry *)((hdr)+1))
  75
  76 #ifdef EXT3_XATTR_DEBUG
  77 # define ea_idebug(inode, f...) do { \
  78                 printk(KERN_DEBUG "inode %s:%lu: ", \
  79                         inode->i_sb->s_id, inode->i_ino); \
  80                 printk(f); \
  81                 printk("\n"); \
  82         } while (0)
  83 # define ea_bdebug(bh, f...) do { \
  84                 char b[BDEVNAME_SIZE]; \
  85                 printk(KERN_DEBUG "block %s:%lu: ", \
  86                         bdevname(bh->b_bdev, b), \
  87                         (unsigned long) bh->b_blocknr); \
  88                 printk(f); \
  89                 printk("\n"); \
  90         } while (0)
  91 #else
  92 # define ea_idebug(f...)
  93 # define ea_bdebug(f...)
  94 #endif
  95
  96 static void ext3_xattr_cache_insert(struct buffer_head *);
  97 static struct buffer_head *ext3_xattr_cache_find(struct inode *,
  98                                                  struct ext3_xattr_header *,
  99                                                  struct mb_cache_entry **);
 100 static void ext3_xattr_rehash(struct ext3_xattr_header *,
 101                               struct ext3_xattr_entry *);
 102 static int ext3_xattr_list(struct inode *inode, char *buffer,
 103                            size_t buffer_size);
 104
 105 static struct mb_cache *ext3_xattr_cache;
 106
 107 static struct xattr_handler *ext3_xattr_handler_map[] = {
 108         [EXT3_XATTR_INDEX_USER]              = &ext3_xattr_user_handler,
 109 #ifdef CONFIG_EXT3_FS_POSIX_ACL
 110         [EXT3_XATTR_INDEX_POSIX_ACL_ACCESS]  = &ext3_xattr_acl_access_handler,
 111         [EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext3_xattr_acl_default_handler,
 112 #endif
 113         [EXT3_XATTR_INDEX_TRUSTED]           = &ext3_xattr_trusted_handler,
 114 #ifdef CONFIG_EXT3_FS_SECURITY
 115         [EXT3_XATTR_INDEX_SECURITY]          = &ext3_xattr_security_handler,
 116 #endif
 117 };
 118
 119 struct xattr_handler *ext3_xattr_handlers[] = {
 120         &ext3_xattr_user_handler,
 121         &ext3_xattr_trusted_handler,
 122 #ifdef CONFIG_EXT3_FS_POSIX_ACL
 123         &ext3_xattr_acl_access_handler,
 124         &ext3_xattr_acl_default_handler,
 125 #endif
 126 #ifdef CONFIG_EXT3_FS_SECURITY
 127         &ext3_xattr_security_handler,
 128 #endif
 129         NULL
 130 };
 131
 132 static inline struct xattr_handler *
 133 ext3_xattr_handler(int name_index)
 134 {
 135         struct xattr_handler *handler = NULL;
 136
 137         if (name_index > 0 && name_index < ARRAY_SIZE(ext3_xattr_handler_map))
 138                 handler = ext3_xattr_handler_map[name_index];
 139         return handler;
 140 }
 141
 142 /*
 143  * Inode operation listxattr()
 144  *
 145  * dentry->d_inode->i_mutex: don't care
 146  */
 147 ssize_t
 148 ext3_listxattr(struct dentry *dentry, char *buffer, size_t size)
 149 {
 150         return ext3_xattr_list(dentry->d_inode, buffer, size);
 151 }
 152
 153 static int
 154 ext3_xattr_check_names(struct ext3_xattr_entry *entry, void *end)
 155 {
 156         while (!IS_LAST_ENTRY(entry)) {
 157                 struct ext3_xattr_entry *next = EXT3_XATTR_NEXT(entry);
 158                 if ((void *)next >= end)
 159                         return -EIO;
 160                 entry = next;
 161         }
 162         return 0;
 163 }
 164
 165 static inline int
 166 ext3_xattr_check_block(struct buffer_head *bh)
 167 {
 168         int error;
 169
 170         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
 171             BHDR(bh)->h_blocks != cpu_to_le32(1))
 172                 return -EIO;
 173         error = ext3_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
 174         return error;
 175 }
 176
 177 static inline int
 178 ext3_xattr_check_entry(struct ext3_xattr_entry *entry, size_t size)
 179 {
 180         size_t value_size = le32_to_cpu(entry->e_value_size);
 181
 182         if (entry->e_value_block != 0 || value_size > size ||
 183             le16_to_cpu(entry->e_value_offs) + value_size > size)
 184                 return -EIO;
 185         return 0;
 186 }
 187
 188 static int
 189 ext3_xattr_find_entry(struct ext3_xattr_entry **pentry, int name_index,
 190                       const char *name, size_t size, int sorted)
 191 {
 192         struct ext3_xattr_entry *entry;
 193         size_t name_len;
 194         int cmp = 1;
 195
 196         if (name == NULL)
 197                 return -EINVAL;
 198         name_len = strlen(name);
 199         entry = *pentry;
 200         for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
 201                 cmp = name_index - entry->e_name_index;
 202                 if (!cmp)
 203                         cmp = name_len - entry->e_name_len;
 204                 if (!cmp)
 205                         cmp = memcmp(name, entry->e_name, name_len);
 206                 if (cmp <= 0 && (sorted || cmp == 0))
 207                         break;
 208         }
 209         *pentry = entry;
 210         if (!cmp && ext3_xattr_check_entry(entry, size))
 211                         return -EIO;
 212         return cmp ? -ENODATA : 0;
 213 }
 214
 215 static int
 216 ext3_xattr_block_get(struct inode *inode, int name_index, const char *name,
 217                      void *buffer, size_t buffer_size)
 218 {
 219         struct buffer_head *bh = NULL;
 220         struct ext3_xattr_entry *entry;
 221         size_t size;
 222         int error;
 223
 224         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 225                   name_index, name, buffer, (long)buffer_size);
 226
 227         error = -ENODATA;
 228         if (!EXT3_I(inode)->i_file_acl)
 229                 goto cleanup;
 230         ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
 231         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
 232         if (!bh)
 233                 goto cleanup;
 234         ea_bdebug(bh, "b_count=%d, refcount=%d",
 235                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 236         if (ext3_xattr_check_block(bh)) {
 237 bad_block:      ext3_error(inode->i_sb, __func__,
 238                            "inode %lu: bad block "E3FSBLK, inode->i_ino,
 239                            EXT3_I(inode)->i_file_acl);
 240                 error = -EIO;
 241                 goto cleanup;
 242         }
 243         ext3_xattr_cache_insert(bh);
 244         entry = BFIRST(bh);
 245         error = ext3_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
 246         if (error == -EIO)
 247                 goto bad_block;
 248         if (error)
 249                 goto cleanup;
 250         size = le32_to_cpu(entry->e_value_size);
 251         if (buffer) {
 252                 error = -ERANGE;
 253                 if (size > buffer_size)
 254                         goto cleanup;
 255                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
 256                        size);
 257         }
 258         error = size;
 259
 260 cleanup:
 261         brelse(bh);
 262         return error;
 263 }
 264
 265 static int
 266 ext3_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 267                      void *buffer, size_t buffer_size)
 268 {
 269         struct ext3_xattr_ibody_header *header;
 270         struct ext3_xattr_entry *entry;
 271         struct ext3_inode *raw_inode;
 272         struct ext3_iloc iloc;
 273         size_t size;
 274         void *end;
 275         int error;
 276
 277         if (!(EXT3_I(inode)->i_state & EXT3_STATE_XATTR))
 278                 return -ENODATA;
 279         error = ext3_get_inode_loc(inode, &iloc);
 280         if (error)
 281                 return error;
 282         raw_inode = ext3_raw_inode(&iloc);
 283         header = IHDR(inode, raw_inode);
 284         entry = IFIRST(header);
 285         end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 286         error = ext3_xattr_check_names(entry, end);
 287         if (error)
 288                 goto cleanup;
 289         error = ext3_xattr_find_entry(&entry, name_index, name,
 290                                       end - (void *)entry, 0);
 291         if (error)
 292                 goto cleanup;
 293         size = le32_to_cpu(entry->e_value_size);
 294         if (buffer) {
 295                 error = -ERANGE;
 296                 if (size > buffer_size)
 297                         goto cleanup;
 298                 memcpy(buffer, (void *)IFIRST(header) +
 299                        le16_to_cpu(entry->e_value_offs), size);
 300         }
 301         error = size;
 302
 303 cleanup:
 304         brelse(iloc.bh);
 305         return error;
 306 }
 307
 308 /*
 309  * ext3_xattr_get()
 310  *
 311  * Copy an extended attribute into the buffer
 312  * provided, or compute the buffer size required.
 313  * Buffer is NULL to compute the size of the buffer required.
 314  *
 315  * Returns a negative error number on failure, or the number of bytes
 316  * used / required on success.
 317  */
 318 int
 319 ext3_xattr_get(struct inode *inode, int name_index, const char *name,
 320                void *buffer, size_t buffer_size)
 321 {
 322         int error;
 323
 324         down_read(&EXT3_I(inode)->xattr_sem);
 325         error = ext3_xattr_ibody_get(inode, name_index, name, buffer,
 326                                      buffer_size);
 327         if (error == -ENODATA)
 328                 error = ext3_xattr_block_get(inode, name_index, name, buffer,
 329                                              buffer_size);
 330         up_read(&EXT3_I(inode)->xattr_sem);
 331         return error;
 332 }
 333
 334 static int
 335 ext3_xattr_list_entries(struct inode *inode, struct ext3_xattr_entry *entry,
 336                         char *buffer, size_t buffer_size)
 337 {
 338         size_t rest = buffer_size;
 339
 340         for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
 341                 struct xattr_handler *handler =
 342                         ext3_xattr_handler(entry->e_name_index);
 343
 344                 if (handler) {
 345                         size_t size = handler->list(inode, buffer, rest,
 346                                                     entry->e_name,
 347                                                     entry->e_name_len);
 348                         if (buffer) {
 349                                 if (size > rest)
 350                                         return -ERANGE;
 351                                 buffer += size;
 352                         }
 353                         rest -= size;
 354                 }
 355         }
 356         return buffer_size - rest;
 357 }
 358
 359 static int
 360 ext3_xattr_block_list(struct inode *inode, char *buffer, size_t buffer_size)
 361 {
 362         struct buffer_head *bh = NULL;
 363         int error;
 364
 365         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 366                   buffer, (long)buffer_size);
 367
 368         error = 0;
 369         if (!EXT3_I(inode)->i_file_acl)
 370                 goto cleanup;
 371         ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
 372         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
 373         error = -EIO;
 374         if (!bh)
 375                 goto cleanup;
 376         ea_bdebug(bh, "b_count=%d, refcount=%d",
 377                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 378         if (ext3_xattr_check_block(bh)) {
 379                 ext3_error(inode->i_sb, __func__,
 380                            "inode %lu: bad block "E3FSBLK, inode->i_ino,
 381                            EXT3_I(inode)->i_file_acl);
 382                 error = -EIO;
 383                 goto cleanup;
 384         }
 385         ext3_xattr_cache_insert(bh);
 386         error = ext3_xattr_list_entries(inode, BFIRST(bh), buffer, buffer_size);
 387
 388 cleanup:
 389         brelse(bh);
 390
 391         return error;
 392 }
 393
 394 static int
 395 ext3_xattr_ibody_list(struct inode *inode, char *buffer, size_t buffer_size)
 396 {
 397         struct ext3_xattr_ibody_header *header;
 398         struct ext3_inode *raw_inode;
 399         struct ext3_iloc iloc;
 400         void *end;
 401         int error;
 402
 403         if (!(EXT3_I(inode)->i_state & EXT3_STATE_XATTR))
 404                 return 0;
 405         error = ext3_get_inode_loc(inode, &iloc);
 406         if (error)
 407                 return error;
 408         raw_inode = ext3_raw_inode(&iloc);
 409         header = IHDR(inode, raw_inode);
 410         end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 411         error = ext3_xattr_check_names(IFIRST(header), end);
 412         if (error)
 413                 goto cleanup;
 414         error = ext3_xattr_list_entries(inode, IFIRST(header),
 415                                         buffer, buffer_size);
 416
 417 cleanup:
 418         brelse(iloc.bh);
 419         return error;
 420 }
 421
 422 /*
 423  * ext3_xattr_list()
 424  *
 425  * Copy a list of attribute names into the buffer
 426  * provided, or compute the buffer size required.
 427  * Buffer is NULL to compute the size of the buffer required.
 428  *
 429  * Returns a negative error number on failure, or the number of bytes
 430  * used / required on success.
 431  */
 432 static int
 433 ext3_xattr_list(struct inode *inode, char *buffer, size_t buffer_size)
 434 {
 435         int i_error, b_error;
 436
 437         down_read(&EXT3_I(inode)->xattr_sem);
 438         i_error = ext3_xattr_ibody_list(inode, buffer, buffer_size);
 439         if (i_error < 0) {
 440                 b_error = 0;
 441         } else {
 442                 if (buffer) {
 443                         buffer += i_error;
 444                         buffer_size -= i_error;
 445                 }
 446                 b_error = ext3_xattr_block_list(inode, buffer, buffer_size);
 447                 if (b_error < 0)
 448                         i_error = 0;
 449         }
 450         up_read(&EXT3_I(inode)->xattr_sem);
 451         return i_error + b_error;
 452 }
 453
 454 /*
 455  * If the EXT3_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 456  * not set, set it.
 457  */
 458 static void ext3_xattr_update_super_block(handle_t *handle,
 459                                           struct super_block *sb)
 460 {
 461         if (EXT3_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR))
 462                 return;
 463
 464         if (ext3_journal_get_write_access(handle, EXT3_SB(sb)->s_sbh) == 0) {
 465                 EXT3_SET_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR);
 466                 ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
 467         }
 468 }
 469
 470 /*
 471  * Release the xattr block BH: If the reference count is > 1, decrement
 472  * it; otherwise free the block.
 473  */
 474 static void
 475 ext3_xattr_release_block(handle_t *handle, struct inode *inode,
 476                          struct buffer_head *bh)
 477 {
 478         struct mb_cache_entry *ce = NULL;
 479         int error = 0;
 480
 481         ce = mb_cache_entry_get(ext3_xattr_cache, bh->b_bdev, bh->b_blocknr);
 482         error = ext3_journal_get_write_access(handle, bh);
 483         if (error)
 484                  goto out;
 485
 486         lock_buffer(bh);
 487
 488         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
 489                 ea_bdebug(bh, "refcount now=0; freeing");
 490                 if (ce)
 491                         mb_cache_entry_free(ce);
 492                 ext3_free_blocks(handle, inode, bh->b_blocknr, 1);
 493                 get_bh(bh);
 494                 ext3_forget(handle, 1, inode, bh, bh->b_blocknr);
 495         } else {
 496                 le32_add_cpu(&BHDR(bh)->h_refcount, -1);
 497                 error = ext3_journal_dirty_metadata(handle, bh);
 498                 if (IS_SYNC(inode))
 499                         handle->h_sync = 1;
 500                 vfs_dq_free_block(inode, 1);
 501                 ea_bdebug(bh, "refcount now=%d; releasing",
 502                           le32_to_cpu(BHDR(bh)->h_refcount));
 503                 if (ce)
 504                         mb_cache_entry_release(ce);
 505         }
 506         unlock_buffer(bh);
 507 out:
 508         ext3_std_error(inode->i_sb, error);
 509         return;
 510 }
 511
 512 struct ext3_xattr_info {
 513         int name_index;
 514         const char *name;
 515         const void *value;
 516         size_t value_len;
 517 };
 518
 519 struct ext3_xattr_search {
 520         struct ext3_xattr_entry *first;
 521         void *base;
 522         void *end;
 523         struct ext3_xattr_entry *here;
 524         int not_found;
 525 };
 526
 527 static int
 528 ext3_xattr_set_entry(struct ext3_xattr_info *i, struct ext3_xattr_search *s)
 529 {
 530         struct ext3_xattr_entry *last;
 531         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
 532
 533         /* Compute min_offs and last. */
 534         last = s->first;
 535         for (; !IS_LAST_ENTRY(last); last = EXT3_XATTR_NEXT(last)) {
 536                 if (!last->e_value_block && last->e_value_size) {
 537                         size_t offs = le16_to_cpu(last->e_value_offs);
 538                         if (offs < min_offs)
 539                                 min_offs = offs;
 540                 }
 541         }
 542         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
 543         if (!s->not_found) {
 544                 if (!s->here->e_value_block && s->here->e_value_size) {
 545                         size_t size = le32_to_cpu(s->here->e_value_size);
 546                         free += EXT3_XATTR_SIZE(size);
 547                 }
 548                 free += EXT3_XATTR_LEN(name_len);
 549         }
 550         if (i->value) {
 551                 if (free < EXT3_XATTR_SIZE(i->value_len) ||
 552                     free < EXT3_XATTR_LEN(name_len) +
 553                            EXT3_XATTR_SIZE(i->value_len))
 554                         return -ENOSPC;
 555         }
 556
 557         if (i->value && s->not_found) {
 558                 /* Insert the new name. */
 559                 size_t size = EXT3_XATTR_LEN(name_len);
 560                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
 561                 memmove((void *)s->here + size, s->here, rest);
 562                 memset(s->here, 0, size);
 563                 s->here->e_name_index = i->name_index;
 564                 s->here->e_name_len = name_len;
 565                 memcpy(s->here->e_name, i->name, name_len);
 566         } else {
 567                 if (!s->here->e_value_block && s->here->e_value_size) {
 568                         void *first_val = s->base + min_offs;
 569                         size_t offs = le16_to_cpu(s->here->e_value_offs);
 570                         void *val = s->base + offs;
 571                         size_t size = EXT3_XATTR_SIZE(
 572                                 le32_to_cpu(s->here->e_value_size));
 573
 574                         if (i->value && size == EXT3_XATTR_SIZE(i->value_len)) {
 575                                 /* The old and the new value have the same
 576                                    size. Just replace. */
 577                                 s->here->e_value_size =
 578                                         cpu_to_le32(i->value_len);
 579                                 memset(val + size - EXT3_XATTR_PAD, 0,
 580                                        EXT3_XATTR_PAD); /* Clear pad bytes. */
 581                                 memcpy(val, i->value, i->value_len);
 582                                 return 0;
 583                         }
 584
 585                         /* Remove the old value. */
 586                         memmove(first_val + size, first_val, val - first_val);
 587                         memset(first_val, 0, size);
 588                         s->here->e_value_size = 0;
 589                         s->here->e_value_offs = 0;
 590                         min_offs += size;
 591
 592                         /* Adjust all value offsets. */
 593                         last = s->first;
 594                         while (!IS_LAST_ENTRY(last)) {
 595                                 size_t o = le16_to_cpu(last->e_value_offs);
 596                                 if (!last->e_value_block &&
 597                                     last->e_value_size && o < offs)
 598                                         last->e_value_offs =
 599                                                 cpu_to_le16(o + size);
 600                                 last = EXT3_XATTR_NEXT(last);
 601                         }
 602                 }
 603                 if (!i->value) {
 604                         /* Remove the old name. */
 605                         size_t size = EXT3_XATTR_LEN(name_len);
 606                         last = ENTRY((void *)last - size);
 607                         memmove(s->here, (void *)s->here + size,
 608                                 (void *)last - (void *)s->here + sizeof(__u32));
 609                         memset(last, 0, size);
 610                 }
 611         }
 612
 613         if (i->value) {
 614                 /* Insert the new value. */
 615                 s->here->e_value_size = cpu_to_le32(i->value_len);
 616                 if (i->value_len) {
 617                         size_t size = EXT3_XATTR_SIZE(i->value_len);
 618                         void *val = s->base + min_offs - size;
 619                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
 620                         memset(val + size - EXT3_XATTR_PAD, 0,
 621                                EXT3_XATTR_PAD); /* Clear the pad bytes. */
 622                         memcpy(val, i->value, i->value_len);
 623                 }
 624         }
 625         return 0;
 626 }
 627
 628 struct ext3_xattr_block_find {
 629         struct ext3_xattr_search s;
 630         struct buffer_head *bh;
 631 };
 632
 633 static int
 634 ext3_xattr_block_find(struct inode *inode, struct ext3_xattr_info *i,
 635                       struct ext3_xattr_block_find *bs)
 636 {
 637         struct super_block *sb = inode->i_sb;
 638         int error;
 639
 640         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
 641                   i->name_index, i->name, i->value, (long)i->value_len);
 642
 643         if (EXT3_I(inode)->i_file_acl) {
 644                 /* The inode already has an extended attribute block. */
 645                 bs->bh = sb_bread(sb, EXT3_I(inode)->i_file_acl);
 646                 error = -EIO;
 647                 if (!bs->bh)
 648                         goto cleanup;
 649                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
 650                         atomic_read(&(bs->bh->b_count)),
 651                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
 652                 if (ext3_xattr_check_block(bs->bh)) {
 653                         ext3_error(sb, __func__,
 654                                 "inode %lu: bad block "E3FSBLK, inode->i_ino,
 655                                 EXT3_I(inode)->i_file_acl);
 656                         error = -EIO;
 657                         goto cleanup;
 658                 }
 659                 /* Find the named attribute. */
 660                 bs->s.base = BHDR(bs->bh);
 661                 bs->s.first = BFIRST(bs->bh);
 662                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
 663                 bs->s.here = bs->s.first;
 664                 error = ext3_xattr_find_entry(&bs->s.here, i->name_index,
 665                                               i->name, bs->bh->b_size, 1);
 666                 if (error && error != -ENODATA)
 667                         goto cleanup;
 668                 bs->s.not_found = error;
 669         }
 670         error = 0;
 671
 672 cleanup:
 673         return error;
 674 }
 675
 676 static int
 677 ext3_xattr_block_set(handle_t *handle, struct inode *inode,
 678                      struct ext3_xattr_info *i,
 679                      struct ext3_xattr_block_find *bs)
 680 {
 681         struct super_block *sb = inode->i_sb;
 682         struct buffer_head *new_bh = NULL;
 683         struct ext3_xattr_search *s = &bs->s;
 684         struct mb_cache_entry *ce = NULL;
 685         int error = 0;
 686
 687 #define header(x) ((struct ext3_xattr_header *)(x))
 688
 689         if (i->value && i->value_len > sb->s_blocksize)
 690                 return -ENOSPC;
 691         if (s->base) {
 692                 ce = mb_cache_entry_get(ext3_xattr_cache, bs->bh->b_bdev,
 693                                         bs->bh->b_blocknr);
 694                 error = ext3_journal_get_write_access(handle, bs->bh);
 695                 if (error)
 696                         goto cleanup;
 697                 lock_buffer(bs->bh);
 698
 699                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 700                         if (ce) {
 701                                 mb_cache_entry_free(ce);
 702                                 ce = NULL;
 703                         }
 704                         ea_bdebug(bs->bh, "modifying in-place");
 705                         error = ext3_xattr_set_entry(i, s);
 706                         if (!error) {
 707                                 if (!IS_LAST_ENTRY(s->first))
 708                                         ext3_xattr_rehash(header(s->base),
 709                                                           s->here);
 710                                 ext3_xattr_cache_insert(bs->bh);
 711                         }
 712                         unlock_buffer(bs->bh);
 713                         if (error == -EIO)
 714                                 goto bad_block;
 715                         if (!error)
 716                                 error = ext3_journal_dirty_metadata(handle,
 717                                                                     bs->bh);
 718                         if (error)
 719                                 goto cleanup;
 720                         goto inserted;
 721                 } else {
 722                         int offset = (char *)s->here - bs->bh->b_data;
 723
 724                         unlock_buffer(bs->bh);
 725                         journal_release_buffer(handle, bs->bh);
 726
 727                         if (ce) {
 728                                 mb_cache_entry_release(ce);
 729                                 ce = NULL;
 730                         }
 731                         ea_bdebug(bs->bh, "cloning");
 732                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
 733                         error = -ENOMEM;
 734                         if (s->base == NULL)
 735                                 goto cleanup;
 736                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 737                         s->first = ENTRY(header(s->base)+1);
 738                         header(s->base)->h_refcount = cpu_to_le32(1);
 739                         s->here = ENTRY(s->base + offset);
 740                         s->end = s->base + bs->bh->b_size;
 741                 }
 742         } else {
 743                 /* Allocate a buffer where we construct the new block. */
 744                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
 745                 /* assert(header == s->base) */
 746                 error = -ENOMEM;
 747                 if (s->base == NULL)
 748                         goto cleanup;
 749                 header(s->base)->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
 750                 header(s->base)->h_blocks = cpu_to_le32(1);
 751                 header(s->base)->h_refcount = cpu_to_le32(1);
 752                 s->first = ENTRY(header(s->base)+1);
 753                 s->here = ENTRY(header(s->base)+1);
 754                 s->end = s->base + sb->s_blocksize;
 755         }
 756
 757         error = ext3_xattr_set_entry(i, s);
 758         if (error == -EIO)
 759                 goto bad_block;
 760         if (error)
 761                 goto cleanup;
 762         if (!IS_LAST_ENTRY(s->first))
 763                 ext3_xattr_rehash(header(s->base), s->here);
 764
 765 inserted:
 766         if (!IS_LAST_ENTRY(s->first)) {
 767                 new_bh = ext3_xattr_cache_find(inode, header(s->base), &ce);
 768                 if (new_bh) {
 769                         /* We found an identical block in the cache. */
 770                         if (new_bh == bs->bh)
 771                                 ea_bdebug(new_bh, "keeping");
 772                         else {
 773                                 /* The old block is released after updating
 774                                    the inode. */
 775                                 error = -EDQUOT;
 776                                 if (vfs_dq_alloc_block(inode, 1))
 777                                         goto cleanup;
 778                                 error = ext3_journal_get_write_access(handle,
 779                                                                       new_bh);
 780                                 if (error)
 781                                         goto cleanup_dquot;
 782                                 lock_buffer(new_bh);
 783                                 le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
 784                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
 785                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 786                                 unlock_buffer(new_bh);
 787                                 error = ext3_journal_dirty_metadata(handle,
 788                                                                     new_bh);
 789                                 if (error)
 790                                         goto cleanup_dquot;
 791                         }
 792                         mb_cache_entry_release(ce);
 793                         ce = NULL;
 794                 } else if (bs->bh && s->base == bs->bh->b_data) {
 795                         /* We were modifying this block in-place. */
 796                         ea_bdebug(bs->bh, "keeping this block");
 797                         new_bh = bs->bh;
 798                         get_bh(new_bh);
 799                 } else {
 800                         /* We need to allocate a new block */
 801                         ext3_fsblk_t goal = ext3_group_first_block_no(sb,
 802                                                 EXT3_I(inode)->i_block_group);
 803                         ext3_fsblk_t block = ext3_new_block(handle, inode,
 804                                                         goal, &error);
 805                         if (error)
 806                                 goto cleanup;
 807                         ea_idebug(inode, "creating block %d", block);
 808
 809                         new_bh = sb_getblk(sb, block);
 810                         if (!new_bh) {
 811 getblk_failed:
 812                                 ext3_free_blocks(handle, inode, block, 1);
 813                                 error = -EIO;
 814                                 goto cleanup;
 815                         }
 816                         lock_buffer(new_bh);
 817                         error = ext3_journal_get_create_access(handle, new_bh);
 818                         if (error) {
 819                                 unlock_buffer(new_bh);
 820                                 goto getblk_failed;
 821                         }
 822                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
 823                         set_buffer_uptodate(new_bh);
 824                         unlock_buffer(new_bh);
 825                         ext3_xattr_cache_insert(new_bh);
 826                         error = ext3_journal_dirty_metadata(handle, new_bh);
 827                         if (error)
 828                                 goto cleanup;
 829                 }
 830         }
 831
 832         /* Update the inode. */
 833         EXT3_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
 834
 835         /* Drop the previous xattr block. */
 836         if (bs->bh && bs->bh != new_bh)
 837                 ext3_xattr_release_block(handle, inode, bs->bh);
 838         error = 0;
 839
 840 cleanup:
 841         if (ce)
 842                 mb_cache_entry_release(ce);
 843         brelse(new_bh);
 844         if (!(bs->bh && s->base == bs->bh->b_data))
 845                 kfree(s->base);
 846
 847         return error;
 848
 849 cleanup_dquot:
 850         vfs_dq_free_block(inode, 1);
 851         goto cleanup;
 852
 853 bad_block:
 854         ext3_error(inode->i_sb, __func__,
 855                    "inode %lu: bad block "E3FSBLK, inode->i_ino,
 856                    EXT3_I(inode)->i_file_acl);
 857         goto cleanup;
 858
 859 #undef header
 860 }
 861
 862 struct ext3_xattr_ibody_find {
 863         struct ext3_xattr_search s;
 864         struct ext3_iloc iloc;
 865 };
 866
 867 static int
 868 ext3_xattr_ibody_find(struct inode *inode, struct ext3_xattr_info *i,
 869                       struct ext3_xattr_ibody_find *is)
 870 {
 871         struct ext3_xattr_ibody_header *header;
 872         struct ext3_inode *raw_inode;
 873         int error;
 874
 875         if (EXT3_I(inode)->i_extra_isize == 0)
 876                 return 0;
 877         raw_inode = ext3_raw_inode(&is->iloc);
 878         header = IHDR(inode, raw_inode);
 879         is->s.base = is->s.first = IFIRST(header);
 880         is->s.here = is->s.first;
 881         is->s.end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 882         if (EXT3_I(inode)->i_state & EXT3_STATE_XATTR) {
 883                 error = ext3_xattr_check_names(IFIRST(header), is->s.end);
 884                 if (error)
 885                         return error;
 886                 /* Find the named attribute. */
 887                 error = ext3_xattr_find_entry(&is->s.here, i->name_index,
 888                                               i->name, is->s.end -
 889                                               (void *)is->s.base, 0);
 890                 if (error && error != -ENODATA)
 891                         return error;
 892                 is->s.not_found = error;
 893         }
 894         return 0;
 895 }
 896
 897 static int
 898 ext3_xattr_ibody_set(handle_t *handle, struct inode *inode,
 899                      struct ext3_xattr_info *i,
 900                      struct ext3_xattr_ibody_find *is)
 901 {
 902         struct ext3_xattr_ibody_header *header;
 903         struct ext3_xattr_search *s = &is->s;
 904         int error;
 905
 906         if (EXT3_I(inode)->i_extra_isize == 0)
 907                 return -ENOSPC;
 908         error = ext3_xattr_set_entry(i, s);
 909         if (error)
 910                 return error;
 911         header = IHDR(inode, ext3_raw_inode(&is->iloc));
 912         if (!IS_LAST_ENTRY(s->first)) {
 913                 header->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
 914                 EXT3_I(inode)->i_state |= EXT3_STATE_XATTR;
 915         } else {
 916                 header->h_magic = cpu_to_le32(0);
 917                 EXT3_I(inode)->i_state &= ~EXT3_STATE_XATTR;
 918         }
 919         return 0;
 920 }
 921
 922 /*
 923  * ext3_xattr_set_handle()
 924  *
 925  * Create, replace or remove an extended attribute for this inode. Buffer
 926  * is NULL to remove an existing extended attribute, and non-NULL to
 927  * either replace an existing extended attribute, or create a new extended
 928  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 929  * specify that an extended attribute must exist and must not exist
 930  * previous to the call, respectively.
 931  *
 932  * Returns 0, or a negative error number on failure.
 933  */
 934 int
 935 ext3_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
 936                       const char *name, const void *value, size_t value_len,
 937                       int flags)
 938 {
 939         struct ext3_xattr_info i = {
 940                 .name_index = name_index,
 941                 .name = name,
 942                 .value = value,
 943                 .value_len = value_len,
 944
 945         };
 946         struct ext3_xattr_ibody_find is = {
 947                 .s = { .not_found = -ENODATA, },
 948         };
 949         struct ext3_xattr_block_find bs = {
 950                 .s = { .not_found = -ENODATA, },
 951         };
 952         int error;
 953
 954         if (!name)
 955                 return -EINVAL;
 956         if (strlen(name) > 255)
 957                 return -ERANGE;
 958         down_write(&EXT3_I(inode)->xattr_sem);
 959         error = ext3_get_inode_loc(inode, &is.iloc);
 960         if (error)
 961                 goto cleanup;
 962
 963         if (EXT3_I(inode)->i_state & EXT3_STATE_NEW) {
 964                 struct ext3_inode *raw_inode = ext3_raw_inode(&is.iloc);
 965                 memset(raw_inode, 0, EXT3_SB(inode->i_sb)->s_inode_size);
 966                 EXT3_I(inode)->i_state &= ~EXT3_STATE_NEW;
 967         }
 968
 969         error = ext3_xattr_ibody_find(inode, &i, &is);
 970         if (error)
 971                 goto cleanup;
 972         if (is.s.not_found)
 973                 error = ext3_xattr_block_find(inode, &i, &bs);
 974         if (error)
 975                 goto cleanup;
 976         if (is.s.not_found && bs.s.not_found) {
 977                 error = -ENODATA;
 978                 if (flags & XATTR_REPLACE)
 979                         goto cleanup;
 980                 error = 0;
 981                 if (!value)
 982                         goto cleanup;
 983         } else {
 984                 error = -EEXIST;
 985                 if (flags & XATTR_CREATE)
 986                         goto cleanup;
 987         }
 988         error = ext3_journal_get_write_access(handle, is.iloc.bh);
 989         if (error)
 990                 goto cleanup;
 991         if (!value) {
 992                 if (!is.s.not_found)
 993                         error = ext3_xattr_ibody_set(handle, inode, &i, &is);
 994                 else if (!bs.s.not_found)
 995                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
 996         } else {
 997                 error = ext3_xattr_ibody_set(handle, inode, &i, &is);
 998                 if (!error && !bs.s.not_found) {
 999                         i.value = NULL;
1000                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1001                 } else if (error == -ENOSPC) {
1002                         if (EXT3_I(inode)->i_file_acl && !bs.s.base) {
1003                                 error = ext3_xattr_block_find(inode, &i, &bs);
1004                                 if (error)
1005                                         goto cleanup;
1006                         }
1007                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1008                         if (error)
1009                                 goto cleanup;
1010                         if (!is.s.not_found) {
1011                                 i.value = NULL;
1012                                 error = ext3_xattr_ibody_set(handle, inode, &i,
1013                                                              &is);
1014                         }
1015                 }
1016         }
1017         if (!error) {
1018                 ext3_xattr_update_super_block(handle, inode->i_sb);
1019                 inode->i_ctime = CURRENT_TIME_SEC;
1020                 error = ext3_mark_iloc_dirty(handle, inode, &is.iloc);
1021                 /*
1022                  * The bh is consumed by ext3_mark_iloc_dirty, even with
1023                  * error != 0.
1024                  */
1025                 is.iloc.bh = NULL;
1026                 if (IS_SYNC(inode))
1027                         handle->h_sync = 1;
1028         }
1029
1030 cleanup:
1031         brelse(is.iloc.bh);
1032         brelse(bs.bh);
1033         up_write(&EXT3_I(inode)->xattr_sem);
1034         return error;
1035 }
1036
1037 /*
1038  * ext3_xattr_set()
1039  *
1040  * Like ext3_xattr_set_handle, but start from an inode. This extended
1041  * attribute modification is a filesystem transaction by itself.
1042  *
1043  * Returns 0, or a negative error number on failure.
1044  */
1045 int
1046 ext3_xattr_set(struct inode *inode, int name_index, const char *name,
1047                const void *value, size_t value_len, int flags)
1048 {
1049         handle_t *handle;
1050         int error, retries = 0;
1051
1052 retry:
1053         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
1054         if (IS_ERR(handle)) {
1055                 error = PTR_ERR(handle);
1056         } else {
1057                 int error2;
1058
1059                 error = ext3_xattr_set_handle(handle, inode, name_index, name,
1060                                               value, value_len, flags);
1061                 error2 = ext3_journal_stop(handle);
1062                 if (error == -ENOSPC &&
1063                     ext3_should_retry_alloc(inode->i_sb, &retries))
1064                         goto retry;
1065                 if (error == 0)
1066                         error = error2;
1067         }
1068
1069         return error;
1070 }
1071
1072 /*
1073  * ext3_xattr_delete_inode()
1074  *
1075  * Free extended attribute resources associated with this inode. This
1076  * is called immediately before an inode is freed. We have exclusive
1077  * access to the inode.
1078  */
1079 void
1080 ext3_xattr_delete_inode(handle_t *handle, struct inode *inode)
1081 {
1082         struct buffer_head *bh = NULL;
1083
1084         if (!EXT3_I(inode)->i_file_acl)
1085                 goto cleanup;
1086         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
1087         if (!bh) {
1088                 ext3_error(inode->i_sb, __func__,
1089                         "inode %lu: block "E3FSBLK" read error", inode->i_ino,
1090                         EXT3_I(inode)->i_file_acl);
1091                 goto cleanup;
1092         }
1093         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
1094             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1095                 ext3_error(inode->i_sb, __func__,
1096                         "inode %lu: bad block "E3FSBLK, inode->i_ino,
1097                         EXT3_I(inode)->i_file_acl);
1098                 goto cleanup;
1099         }
1100         ext3_xattr_release_block(handle, inode, bh);
1101         EXT3_I(inode)->i_file_acl = 0;
1102
1103 cleanup:
1104         brelse(bh);
1105 }
1106
1107 /*
1108  * ext3_xattr_put_super()
1109  *
1110  * This is called when a file system is unmounted.
1111  */
1112 void
1113 ext3_xattr_put_super(struct super_block *sb)
1114 {
1115         mb_cache_shrink(sb->s_bdev);
1116 }
1117
1118 /*
1119  * ext3_xattr_cache_insert()
1120  *
1121  * Create a new entry in the extended attribute cache, and insert
1122  * it unless such an entry is already in the cache.
1123  *
1124  * Returns 0, or a negative error number on failure.
1125  */
1126 static void
1127 ext3_xattr_cache_insert(struct buffer_head *bh)
1128 {
1129         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1130         struct mb_cache_entry *ce;
1131         int error;
1132
1133         ce = mb_cache_entry_alloc(ext3_xattr_cache, GFP_NOFS);
1134         if (!ce) {
1135                 ea_bdebug(bh, "out of memory");
1136                 return;
1137         }
1138         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
1139         if (error) {
1140                 mb_cache_entry_free(ce);
1141                 if (error == -EBUSY) {
1142                         ea_bdebug(bh, "already in cache");
1143                         error = 0;
1144                 }
1145         } else {
1146                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1147                 mb_cache_entry_release(ce);
1148         }
1149 }
1150
1151 /*
1152  * ext3_xattr_cmp()
1153  *
1154  * Compare two extended attribute blocks for equality.
1155  *
1156  * Returns 0 if the blocks are equal, 1 if they differ, and
1157  * a negative error number on errors.
1158  */
1159 static int
1160 ext3_xattr_cmp(struct ext3_xattr_header *header1,
1161                struct ext3_xattr_header *header2)
1162 {
1163         struct ext3_xattr_entry *entry1, *entry2;
1164
1165         entry1 = ENTRY(header1+1);
1166         entry2 = ENTRY(header2+1);
1167         while (!IS_LAST_ENTRY(entry1)) {
1168                 if (IS_LAST_ENTRY(entry2))
1169                         return 1;
1170                 if (entry1->e_hash != entry2->e_hash ||
1171                     entry1->e_name_index != entry2->e_name_index ||
1172                     entry1->e_name_len != entry2->e_name_len ||
1173                     entry1->e_value_size != entry2->e_value_size ||
1174                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1175                         return 1;
1176                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1177                         return -EIO;
1178                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1179                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1180                            le32_to_cpu(entry1->e_value_size)))
1181                         return 1;
1182
1183                 entry1 = EXT3_XATTR_NEXT(entry1);
1184                 entry2 = EXT3_XATTR_NEXT(entry2);
1185         }
1186         if (!IS_LAST_ENTRY(entry2))
1187                 return 1;
1188         return 0;
1189 }
1190
1191 /*
1192  * ext3_xattr_cache_find()
1193  *
1194  * Find an identical extended attribute block.
1195  *
1196  * Returns a pointer to the block found, or NULL if such a block was
1197  * not found or an error occurred.
1198  */
1199 static struct buffer_head *
1200 ext3_xattr_cache_find(struct inode *inode, struct ext3_xattr_header *header,
1201                       struct mb_cache_entry **pce)
1202 {
1203         __u32 hash = le32_to_cpu(header->h_hash);
1204         struct mb_cache_entry *ce;
1205
1206         if (!header->h_hash)
1207                 return NULL;  /* never share */
1208         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1209 again:
1210         ce = mb_cache_entry_find_first(ext3_xattr_cache, 0,
1211                                        inode->i_sb->s_bdev, hash);
1212         while (ce) {
1213                 struct buffer_head *bh;
1214
1215                 if (IS_ERR(ce)) {
1216                         if (PTR_ERR(ce) == -EAGAIN)
1217                                 goto again;
1218                         break;
1219                 }
1220                 bh = sb_bread(inode->i_sb, ce->e_block);
1221                 if (!bh) {
1222                         ext3_error(inode->i_sb, __func__,
1223                                 "inode %lu: block %lu read error",
1224                                 inode->i_ino, (unsigned long) ce->e_block);
1225                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1226                                 EXT3_XATTR_REFCOUNT_MAX) {
1227                         ea_idebug(inode, "block %lu refcount %d>=%d",
1228                                   (unsigned long) ce->e_block,
1229                                   le32_to_cpu(BHDR(bh)->h_refcount),
1230                                           EXT3_XATTR_REFCOUNT_MAX);
1231                 } else if (ext3_xattr_cmp(header, BHDR(bh)) == 0) {
1232                         *pce = ce;
1233                         return bh;
1234                 }
1235                 brelse(bh);
1236                 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
1237         }
1238         return NULL;
1239 }
1240
1241 #define NAME_HASH_SHIFT 5
1242 #define VALUE_HASH_SHIFT 16
1243
1244 /*
1245  * ext3_xattr_hash_entry()
1246  *
1247  * Compute the hash of an extended attribute.
1248  */
1249 static inline void ext3_xattr_hash_entry(struct ext3_xattr_header *header,
1250                                          struct ext3_xattr_entry *entry)
1251 {
1252         __u32 hash = 0;
1253         char *name = entry->e_name;
1254         int n;
1255
1256         for (n=0; n < entry->e_name_len; n++) {
1257                 hash = (hash << NAME_HASH_SHIFT) ^
1258                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1259                        *name++;
1260         }
1261
1262         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1263                 __le32 *value = (__le32 *)((char *)header +
1264                         le16_to_cpu(entry->e_value_offs));
1265                 for (n = (le32_to_cpu(entry->e_value_size) +
1266                      EXT3_XATTR_ROUND) >> EXT3_XATTR_PAD_BITS; n; n--) {
1267                         hash = (hash << VALUE_HASH_SHIFT) ^
1268                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1269                                le32_to_cpu(*value++);
1270                 }
1271         }
1272         entry->e_hash = cpu_to_le32(hash);
1273 }
1274
1275 #undef NAME_HASH_SHIFT
1276 #undef VALUE_HASH_SHIFT
1277
1278 #define BLOCK_HASH_SHIFT 16
1279
1280 /*
1281  * ext3_xattr_rehash()
1282  *
1283  * Re-compute the extended attribute hash value after an entry has changed.
1284  */
1285 static void ext3_xattr_rehash(struct ext3_xattr_header *header,
1286                               struct ext3_xattr_entry *entry)
1287 {
1288         struct ext3_xattr_entry *here;
1289         __u32 hash = 0;
1290
1291         ext3_xattr_hash_entry(header, entry);
1292         here = ENTRY(header+1);
1293         while (!IS_LAST_ENTRY(here)) {
1294                 if (!here->e_hash) {
1295                         /* Block is not shared if an entry's hash value == 0 */
1296                         hash = 0;
1297                         break;
1298                 }
1299                 hash = (hash << BLOCK_HASH_SHIFT) ^
1300                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1301                        le32_to_cpu(here->e_hash);
1302                 here = EXT3_XATTR_NEXT(here);
1303         }
1304         header->h_hash = cpu_to_le32(hash);
1305 }
1306
1307 #undef BLOCK_HASH_SHIFT
1308
1309 int __init
1310 init_ext3_xattr(void)
1311 {
1312         ext3_xattr_cache = mb_cache_create("ext3_xattr", NULL,
1313                 sizeof(struct mb_cache_entry) +
1314                 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1315         if (!ext3_xattr_cache)
1316                 return -ENOMEM;
1317         return 0;
1318 }
1319
1320 void
1321 exit_ext3_xattr(void)
1322 {
1323         if (ext3_xattr_cache)
1324                 mb_cache_destroy(ext3_xattr_cache);
1325         ext3_xattr_cache = NULL;
1326 }