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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
 103 static struct mb_cache *ext3_xattr_cache;
 104
 105 static struct xattr_handler *ext3_xattr_handler_map[] = {
 106         [EXT3_XATTR_INDEX_USER]              = &ext3_xattr_user_handler,
 107 #ifdef CONFIG_EXT3_FS_POSIX_ACL
 108         [EXT3_XATTR_INDEX_POSIX_ACL_ACCESS]  = &ext3_xattr_acl_access_handler,
 109         [EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext3_xattr_acl_default_handler,
 110 #endif
 111         [EXT3_XATTR_INDEX_TRUSTED]           = &ext3_xattr_trusted_handler,
 112 #ifdef CONFIG_EXT3_FS_SECURITY
 113         [EXT3_XATTR_INDEX_SECURITY]          = &ext3_xattr_security_handler,
 114 #endif
 115 };
 116
 117 struct xattr_handler *ext3_xattr_handlers[] = {
 118         &ext3_xattr_user_handler,
 119         &ext3_xattr_trusted_handler,
 120 #ifdef CONFIG_EXT3_FS_POSIX_ACL
 121         &ext3_xattr_acl_access_handler,
 122         &ext3_xattr_acl_default_handler,
 123 #endif
 124 #ifdef CONFIG_EXT3_FS_SECURITY
 125         &ext3_xattr_security_handler,
 126 #endif
 127         NULL
 128 };
 129
 130 static inline struct xattr_handler *
 131 ext3_xattr_handler(int name_index)
 132 {
 133         struct xattr_handler *handler = NULL;
 134
 135         if (name_index > 0 && name_index < ARRAY_SIZE(ext3_xattr_handler_map))
 136                 handler = ext3_xattr_handler_map[name_index];
 137         return handler;
 138 }
 139
 140 /*
 141  * Inode operation listxattr()
 142  *
 143  * dentry->d_inode->i_mutex: don't care
 144  */
 145 ssize_t
 146 ext3_listxattr(struct dentry *dentry, char *buffer, size_t size)
 147 {
 148         return ext3_xattr_list(dentry->d_inode, buffer, size);
 149 }
 150
 151 static int
 152 ext3_xattr_check_names(struct ext3_xattr_entry *entry, void *end)
 153 {
 154         while (!IS_LAST_ENTRY(entry)) {
 155                 struct ext3_xattr_entry *next = EXT3_XATTR_NEXT(entry);
 156                 if ((void *)next >= end)
 157                         return -EIO;
 158                 entry = next;
 159         }
 160         return 0;
 161 }
 162
 163 static inline int
 164 ext3_xattr_check_block(struct buffer_head *bh)
 165 {
 166         int error;
 167
 168         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
 169             BHDR(bh)->h_blocks != cpu_to_le32(1))
 170                 return -EIO;
 171         error = ext3_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
 172         return error;
 173 }
 174
 175 static inline int
 176 ext3_xattr_check_entry(struct ext3_xattr_entry *entry, size_t size)
 177 {
 178         size_t value_size = le32_to_cpu(entry->e_value_size);
 179
 180         if (entry->e_value_block != 0 || value_size > size ||
 181             le16_to_cpu(entry->e_value_offs) + value_size > size)
 182                 return -EIO;
 183         return 0;
 184 }
 185
 186 static int
 187 ext3_xattr_find_entry(struct ext3_xattr_entry **pentry, int name_index,
 188                       const char *name, size_t size, int sorted)
 189 {
 190         struct ext3_xattr_entry *entry;
 191         size_t name_len;
 192         int cmp = 1;
 193
 194         if (name == NULL)
 195                 return -EINVAL;
 196         name_len = strlen(name);
 197         entry = *pentry;
 198         for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
 199                 cmp = name_index - entry->e_name_index;
 200                 if (!cmp)
 201                         cmp = name_len - entry->e_name_len;
 202                 if (!cmp)
 203                         cmp = memcmp(name, entry->e_name, name_len);
 204                 if (cmp <= 0 && (sorted || cmp == 0))
 205                         break;
 206         }
 207         *pentry = entry;
 208         if (!cmp && ext3_xattr_check_entry(entry, size))
 209                         return -EIO;
 210         return cmp ? -ENODATA : 0;
 211 }
 212
 213 static int
 214 ext3_xattr_block_get(struct inode *inode, int name_index, const char *name,
 215                      void *buffer, size_t buffer_size)
 216 {
 217         struct buffer_head *bh = NULL;
 218         struct ext3_xattr_entry *entry;
 219         size_t size;
 220         int error;
 221
 222         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 223                   name_index, name, buffer, (long)buffer_size);
 224
 225         error = -ENODATA;
 226         if (!EXT3_I(inode)->i_file_acl)
 227                 goto cleanup;
 228         ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
 229         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
 230         if (!bh)
 231                 goto cleanup;
 232         ea_bdebug(bh, "b_count=%d, refcount=%d",
 233                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 234         if (ext3_xattr_check_block(bh)) {
 235 bad_block:      ext3_error(inode->i_sb, __FUNCTION__,
 236                            "inode %lu: bad block "E3FSBLK, inode->i_ino,
 237                            EXT3_I(inode)->i_file_acl);
 238                 error = -EIO;
 239                 goto cleanup;
 240         }
 241         ext3_xattr_cache_insert(bh);
 242         entry = BFIRST(bh);
 243         error = ext3_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
 244         if (error == -EIO)
 245                 goto bad_block;
 246         if (error)
 247                 goto cleanup;
 248         size = le32_to_cpu(entry->e_value_size);
 249         if (buffer) {
 250                 error = -ERANGE;
 251                 if (size > buffer_size)
 252                         goto cleanup;
 253                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
 254                        size);
 255         }
 256         error = size;
 257
 258 cleanup:
 259         brelse(bh);
 260         return error;
 261 }
 262
 263 static int
 264 ext3_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 265                      void *buffer, size_t buffer_size)
 266 {
 267         struct ext3_xattr_ibody_header *header;
 268         struct ext3_xattr_entry *entry;
 269         struct ext3_inode *raw_inode;
 270         struct ext3_iloc iloc;
 271         size_t size;
 272         void *end;
 273         int error;
 274
 275         if (!(EXT3_I(inode)->i_state & EXT3_STATE_XATTR))
 276                 return -ENODATA;
 277         error = ext3_get_inode_loc(inode, &iloc);
 278         if (error)
 279                 return error;
 280         raw_inode = ext3_raw_inode(&iloc);
 281         header = IHDR(inode, raw_inode);
 282         entry = IFIRST(header);
 283         end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 284         error = ext3_xattr_check_names(entry, end);
 285         if (error)
 286                 goto cleanup;
 287         error = ext3_xattr_find_entry(&entry, name_index, name,
 288                                       end - (void *)entry, 0);
 289         if (error)
 290                 goto cleanup;
 291         size = le32_to_cpu(entry->e_value_size);
 292         if (buffer) {
 293                 error = -ERANGE;
 294                 if (size > buffer_size)
 295                         goto cleanup;
 296                 memcpy(buffer, (void *)IFIRST(header) +
 297                        le16_to_cpu(entry->e_value_offs), size);
 298         }
 299         error = size;
 300
 301 cleanup:
 302         brelse(iloc.bh);
 303         return error;
 304 }
 305
 306 /*
 307  * ext3_xattr_get()
 308  *
 309  * Copy an extended attribute into the buffer
 310  * provided, or compute the buffer size required.
 311  * Buffer is NULL to compute the size of the buffer required.
 312  *
 313  * Returns a negative error number on failure, or the number of bytes
 314  * used / required on success.
 315  */
 316 int
 317 ext3_xattr_get(struct inode *inode, int name_index, const char *name,
 318                void *buffer, size_t buffer_size)
 319 {
 320         int error;
 321
 322         down_read(&EXT3_I(inode)->xattr_sem);
 323         error = ext3_xattr_ibody_get(inode, name_index, name, buffer,
 324                                      buffer_size);
 325         if (error == -ENODATA)
 326                 error = ext3_xattr_block_get(inode, name_index, name, buffer,
 327                                              buffer_size);
 328         up_read(&EXT3_I(inode)->xattr_sem);
 329         return error;
 330 }
 331
 332 static int
 333 ext3_xattr_list_entries(struct inode *inode, struct ext3_xattr_entry *entry,
 334                         char *buffer, size_t buffer_size)
 335 {
 336         size_t rest = buffer_size;
 337
 338         for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
 339                 struct xattr_handler *handler =
 340                         ext3_xattr_handler(entry->e_name_index);
 341
 342                 if (handler) {
 343                         size_t size = handler->list(inode, buffer, rest,
 344                                                     entry->e_name,
 345                                                     entry->e_name_len);
 346                         if (buffer) {
 347                                 if (size > rest)
 348                                         return -ERANGE;
 349                                 buffer += size;
 350                         }
 351                         rest -= size;
 352                 }
 353         }
 354         return buffer_size - rest;
 355 }
 356
 357 static int
 358 ext3_xattr_block_list(struct inode *inode, char *buffer, size_t buffer_size)
 359 {
 360         struct buffer_head *bh = NULL;
 361         int error;
 362
 363         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 364                   buffer, (long)buffer_size);
 365
 366         error = 0;
 367         if (!EXT3_I(inode)->i_file_acl)
 368                 goto cleanup;
 369         ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
 370         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
 371         error = -EIO;
 372         if (!bh)
 373                 goto cleanup;
 374         ea_bdebug(bh, "b_count=%d, refcount=%d",
 375                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 376         if (ext3_xattr_check_block(bh)) {
 377                 ext3_error(inode->i_sb, __FUNCTION__,
 378                            "inode %lu: bad block "E3FSBLK, inode->i_ino,
 379                            EXT3_I(inode)->i_file_acl);
 380                 error = -EIO;
 381                 goto cleanup;
 382         }
 383         ext3_xattr_cache_insert(bh);
 384         error = ext3_xattr_list_entries(inode, BFIRST(bh), buffer, buffer_size);
 385
 386 cleanup:
 387         brelse(bh);
 388
 389         return error;
 390 }
 391
 392 static int
 393 ext3_xattr_ibody_list(struct inode *inode, char *buffer, size_t buffer_size)
 394 {
 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_I(inode)->i_state & 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(inode, 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 int
 431 ext3_xattr_list(struct inode *inode, char *buffer, size_t buffer_size)
 432 {
 433         int i_error, b_error;
 434
 435         down_read(&EXT3_I(inode)->xattr_sem);
 436         i_error = ext3_xattr_ibody_list(inode, 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(inode, buffer, buffer_size);
 445                 if (b_error < 0)
 446                         i_error = 0;
 447         }
 448         up_read(&EXT3_I(inode)->xattr_sem);
 449         return i_error + b_error;
 450 }
 451
 452 /*
 453  * If the EXT3_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 454  * not set, set it.
 455  */
 456 static void ext3_xattr_update_super_block(handle_t *handle,
 457                                           struct super_block *sb)
 458 {
 459         if (EXT3_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR))
 460                 return;
 461
 462         if (ext3_journal_get_write_access(handle, EXT3_SB(sb)->s_sbh) == 0) {
 463                 EXT3_SET_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR);
 464                 sb->s_dirt = 1;
 465                 ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
 466         }
 467 }
 468
 469 /*
 470  * Release the xattr block BH: If the reference count is > 1, decrement
 471  * it; otherwise free the block.
 472  */
 473 static void
 474 ext3_xattr_release_block(handle_t *handle, struct inode *inode,
 475                          struct buffer_head *bh)
 476 {
 477         struct mb_cache_entry *ce = NULL;
 478         int error = 0;
 479
 480         ce = mb_cache_entry_get(ext3_xattr_cache, bh->b_bdev, bh->b_blocknr);
 481         error = ext3_journal_get_write_access(handle, bh);
 482         if (error)
 483                  goto out;
 484
 485         lock_buffer(bh);
 486
 487         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
 488                 ea_bdebug(bh, "refcount now=0; freeing");
 489                 if (ce)
 490                         mb_cache_entry_free(ce);
 491                 ext3_free_blocks(handle, inode, bh->b_blocknr, 1);
 492                 get_bh(bh);
 493                 ext3_forget(handle, 1, inode, bh, bh->b_blocknr);
 494         } else {
 495                 le32_add_cpu(&BHDR(bh)->h_refcount, -1);
 496                 error = ext3_journal_dirty_metadata(handle, bh);
 497                 if (IS_SYNC(inode))
 498                         handle->h_sync = 1;
 499                 DQUOT_FREE_BLOCK(inode, 1);
 500                 ea_bdebug(bh, "refcount now=%d; releasing",
 501                           le32_to_cpu(BHDR(bh)->h_refcount));
 502                 if (ce)
 503                         mb_cache_entry_release(ce);
 504         }
 505         unlock_buffer(bh);
 506 out:
 507         ext3_std_error(inode->i_sb, error);
 508         return;
 509 }
 510
 511 struct ext3_xattr_info {
 512         int name_index;
 513         const char *name;
 514         const void *value;
 515         size_t value_len;
 516 };
 517
 518 struct ext3_xattr_search {
 519         struct ext3_xattr_entry *first;
 520         void *base;
 521         void *end;
 522         struct ext3_xattr_entry *here;
 523         int not_found;
 524 };
 525
 526 static int
 527 ext3_xattr_set_entry(struct ext3_xattr_info *i, struct ext3_xattr_search *s)
 528 {
 529         struct ext3_xattr_entry *last;
 530         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
 531
 532         /* Compute min_offs and last. */
 533         last = s->first;
 534         for (; !IS_LAST_ENTRY(last); last = EXT3_XATTR_NEXT(last)) {
 535                 if (!last->e_value_block && last->e_value_size) {
 536                         size_t offs = le16_to_cpu(last->e_value_offs);
 537                         if (offs < min_offs)
 538                                 min_offs = offs;
 539                 }
 540         }
 541         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
 542         if (!s->not_found) {
 543                 if (!s->here->e_value_block && s->here->e_value_size) {
 544                         size_t size = le32_to_cpu(s->here->e_value_size);
 545                         free += EXT3_XATTR_SIZE(size);
 546                 }
 547                 free += EXT3_XATTR_LEN(name_len);
 548         }
 549         if (i->value) {
 550                 if (free < EXT3_XATTR_SIZE(i->value_len) ||
 551                     free < EXT3_XATTR_LEN(name_len) +
 552                            EXT3_XATTR_SIZE(i->value_len))
 553                         return -ENOSPC;
 554         }
 555
 556         if (i->value && s->not_found) {
 557                 /* Insert the new name. */
 558                 size_t size = EXT3_XATTR_LEN(name_len);
 559                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
 560                 memmove((void *)s->here + size, s->here, rest);
 561                 memset(s->here, 0, size);
 562                 s->here->e_name_index = i->name_index;
 563                 s->here->e_name_len = name_len;
 564                 memcpy(s->here->e_name, i->name, name_len);
 565         } else {
 566                 if (!s->here->e_value_block && s->here->e_value_size) {
 567                         void *first_val = s->base + min_offs;
 568                         size_t offs = le16_to_cpu(s->here->e_value_offs);
 569                         void *val = s->base + offs;
 570                         size_t size = EXT3_XATTR_SIZE(
 571                                 le32_to_cpu(s->here->e_value_size));
 572
 573                         if (i->value && size == EXT3_XATTR_SIZE(i->value_len)) {
 574                                 /* The old and the new value have the same
 575                                    size. Just replace. */
 576                                 s->here->e_value_size =
 577                                         cpu_to_le32(i->value_len);
 578                                 memset(val + size - EXT3_XATTR_PAD, 0,
 579                                        EXT3_XATTR_PAD); /* Clear pad bytes. */
 580                                 memcpy(val, i->value, i->value_len);
 581                                 return 0;
 582                         }
 583
 584                         /* Remove the old value. */
 585                         memmove(first_val + size, first_val, val - first_val);
 586                         memset(first_val, 0, size);
 587                         s->here->e_value_size = 0;
 588                         s->here->e_value_offs = 0;
 589                         min_offs += size;
 590
 591                         /* Adjust all value offsets. */
 592                         last = s->first;
 593                         while (!IS_LAST_ENTRY(last)) {
 594                                 size_t o = le16_to_cpu(last->e_value_offs);
 595                                 if (!last->e_value_block &&
 596                                     last->e_value_size && o < offs)
 597                                         last->e_value_offs =
 598                                                 cpu_to_le16(o + size);
 599                                 last = EXT3_XATTR_NEXT(last);
 600                         }
 601                 }
 602                 if (!i->value) {
 603                         /* Remove the old name. */
 604                         size_t size = EXT3_XATTR_LEN(name_len);
 605                         last = ENTRY((void *)last - size);
 606                         memmove(s->here, (void *)s->here + size,
 607                                 (void *)last - (void *)s->here + sizeof(__u32));
 608                         memset(last, 0, size);
 609                 }
 610         }
 611
 612         if (i->value) {
 613                 /* Insert the new value. */
 614                 s->here->e_value_size = cpu_to_le32(i->value_len);
 615                 if (i->value_len) {
 616                         size_t size = EXT3_XATTR_SIZE(i->value_len);
 617                         void *val = s->base + min_offs - size;
 618                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
 619                         memset(val + size - EXT3_XATTR_PAD, 0,
 620                                EXT3_XATTR_PAD); /* Clear the pad bytes. */
 621                         memcpy(val, i->value, i->value_len);
 622                 }
 623         }
 624         return 0;
 625 }
 626
 627 struct ext3_xattr_block_find {
 628         struct ext3_xattr_search s;
 629         struct buffer_head *bh;
 630 };
 631
 632 static int
 633 ext3_xattr_block_find(struct inode *inode, struct ext3_xattr_info *i,
 634                       struct ext3_xattr_block_find *bs)
 635 {
 636         struct super_block *sb = inode->i_sb;
 637         int error;
 638
 639         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
 640                   i->name_index, i->name, i->value, (long)i->value_len);
 641
 642         if (EXT3_I(inode)->i_file_acl) {
 643                 /* The inode already has an extended attribute block. */
 644                 bs->bh = sb_bread(sb, EXT3_I(inode)->i_file_acl);
 645                 error = -EIO;
 646                 if (!bs->bh)
 647                         goto cleanup;
 648                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
 649                         atomic_read(&(bs->bh->b_count)),
 650                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
 651                 if (ext3_xattr_check_block(bs->bh)) {
 652                         ext3_error(sb, __FUNCTION__,
 653                                 "inode %lu: bad block "E3FSBLK, inode->i_ino,
 654                                 EXT3_I(inode)->i_file_acl);
 655                         error = -EIO;
 656                         goto cleanup;
 657                 }
 658                 /* Find the named attribute. */
 659                 bs->s.base = BHDR(bs->bh);
 660                 bs->s.first = BFIRST(bs->bh);
 661                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
 662                 bs->s.here = bs->s.first;
 663                 error = ext3_xattr_find_entry(&bs->s.here, i->name_index,
 664                                               i->name, bs->bh->b_size, 1);
 665                 if (error && error != -ENODATA)
 666                         goto cleanup;
 667                 bs->s.not_found = error;
 668         }
 669         error = 0;
 670
 671 cleanup:
 672         return error;
 673 }
 674
 675 static int
 676 ext3_xattr_block_set(handle_t *handle, struct inode *inode,
 677                      struct ext3_xattr_info *i,
 678                      struct ext3_xattr_block_find *bs)
 679 {
 680         struct super_block *sb = inode->i_sb;
 681         struct buffer_head *new_bh = NULL;
 682         struct ext3_xattr_search *s = &bs->s;
 683         struct mb_cache_entry *ce = NULL;
 684         int error = 0;
 685
 686 #define header(x) ((struct ext3_xattr_header *)(x))
 687
 688         if (i->value && i->value_len > sb->s_blocksize)
 689                 return -ENOSPC;
 690         if (s->base) {
 691                 ce = mb_cache_entry_get(ext3_xattr_cache, bs->bh->b_bdev,
 692                                         bs->bh->b_blocknr);
 693                 error = ext3_journal_get_write_access(handle, bs->bh);
 694                 if (error)
 695                         goto cleanup;
 696                 lock_buffer(bs->bh);
 697
 698                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 699                         if (ce) {
 700                                 mb_cache_entry_free(ce);
 701                                 ce = NULL;
 702                         }
 703                         ea_bdebug(bs->bh, "modifying in-place");
 704                         error = ext3_xattr_set_entry(i, s);
 705                         if (!error) {
 706                                 if (!IS_LAST_ENTRY(s->first))
 707                                         ext3_xattr_rehash(header(s->base),
 708                                                           s->here);
 709                                 ext3_xattr_cache_insert(bs->bh);
 710                         }
 711                         unlock_buffer(bs->bh);
 712                         if (error == -EIO)
 713                                 goto bad_block;
 714                         if (!error)
 715                                 error = ext3_journal_dirty_metadata(handle,
 716                                                                     bs->bh);
 717                         if (error)
 718                                 goto cleanup;
 719                         goto inserted;
 720                 } else {
 721                         int offset = (char *)s->here - bs->bh->b_data;
 722
 723                         unlock_buffer(bs->bh);
 724                         journal_release_buffer(handle, bs->bh);
 725
 726                         if (ce) {
 727                                 mb_cache_entry_release(ce);
 728                                 ce = NULL;
 729                         }
 730                         ea_bdebug(bs->bh, "cloning");
 731                         s->base = kmalloc(bs->bh->b_size, GFP_KERNEL);
 732                         error = -ENOMEM;
 733                         if (s->base == NULL)
 734                                 goto cleanup;
 735                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 736                         s->first = ENTRY(header(s->base)+1);
 737                         header(s->base)->h_refcount = cpu_to_le32(1);
 738                         s->here = ENTRY(s->base + offset);
 739                         s->end = s->base + bs->bh->b_size;
 740                 }
 741         } else {
 742                 /* Allocate a buffer where we construct the new block. */
 743                 s->base = kzalloc(sb->s_blocksize, GFP_KERNEL);
 744                 /* assert(header == s->base) */
 745                 error = -ENOMEM;
 746                 if (s->base == NULL)
 747                         goto cleanup;
 748                 header(s->base)->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
 749                 header(s->base)->h_blocks = cpu_to_le32(1);
 750                 header(s->base)->h_refcount = cpu_to_le32(1);
 751                 s->first = ENTRY(header(s->base)+1);
 752                 s->here = ENTRY(header(s->base)+1);
 753                 s->end = s->base + sb->s_blocksize;
 754         }
 755
 756         error = ext3_xattr_set_entry(i, s);
 757         if (error == -EIO)
 758                 goto bad_block;
 759         if (error)
 760                 goto cleanup;
 761         if (!IS_LAST_ENTRY(s->first))
 762                 ext3_xattr_rehash(header(s->base), s->here);
 763
 764 inserted:
 765         if (!IS_LAST_ENTRY(s->first)) {
 766                 new_bh = ext3_xattr_cache_find(inode, header(s->base), &ce);
 767                 if (new_bh) {
 768                         /* We found an identical block in the cache. */
 769                         if (new_bh == bs->bh)
 770                                 ea_bdebug(new_bh, "keeping");
 771                         else {
 772                                 /* The old block is released after updating
 773                                    the inode. */
 774                                 error = -EDQUOT;
 775                                 if (DQUOT_ALLOC_BLOCK(inode, 1))
 776                                         goto cleanup;
 777                                 error = ext3_journal_get_write_access(handle,
 778                                                                       new_bh);
 779                                 if (error)
 780                                         goto cleanup_dquot;
 781                                 lock_buffer(new_bh);
 782                                 le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
 783                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
 784                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 785                                 unlock_buffer(new_bh);
 786                                 error = ext3_journal_dirty_metadata(handle,
 787                                                                     new_bh);
 788                                 if (error)
 789                                         goto cleanup_dquot;
 790                         }
 791                         mb_cache_entry_release(ce);
 792                         ce = NULL;
 793                 } else if (bs->bh && s->base == bs->bh->b_data) {
 794                         /* We were modifying this block in-place. */
 795                         ea_bdebug(bs->bh, "keeping this block");
 796                         new_bh = bs->bh;
 797                         get_bh(new_bh);
 798                 } else {
 799                         /* We need to allocate a new block */
 800                         ext3_fsblk_t goal = le32_to_cpu(
 801                                         EXT3_SB(sb)->s_es->s_first_data_block) +
 802                                 (ext3_fsblk_t)EXT3_I(inode)->i_block_group *
 803                                 EXT3_BLOCKS_PER_GROUP(sb);
 804                         ext3_fsblk_t block = ext3_new_block(handle, inode,
 805                                                         goal, &error);
 806                         if (error)
 807                                 goto cleanup;
 808                         ea_idebug(inode, "creating block %d", block);
 809
 810                         new_bh = sb_getblk(sb, block);
 811                         if (!new_bh) {
 812 getblk_failed:
 813                                 ext3_free_blocks(handle, inode, block, 1);
 814                                 error = -EIO;
 815                                 goto cleanup;
 816                         }
 817                         lock_buffer(new_bh);
 818                         error = ext3_journal_get_create_access(handle, new_bh);
 819                         if (error) {
 820                                 unlock_buffer(new_bh);
 821                                 goto getblk_failed;
 822                         }
 823                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
 824                         set_buffer_uptodate(new_bh);
 825                         unlock_buffer(new_bh);
 826                         ext3_xattr_cache_insert(new_bh);
 827                         error = ext3_journal_dirty_metadata(handle, new_bh);
 828                         if (error)
 829                                 goto cleanup;
 830                 }
 831         }
 832
 833         /* Update the inode. */
 834         EXT3_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
 835
 836         /* Drop the previous xattr block. */
 837         if (bs->bh && bs->bh != new_bh)
 838                 ext3_xattr_release_block(handle, inode, bs->bh);
 839         error = 0;
 840
 841 cleanup:
 842         if (ce)
 843                 mb_cache_entry_release(ce);
 844         brelse(new_bh);
 845         if (!(bs->bh && s->base == bs->bh->b_data))
 846                 kfree(s->base);
 847
 848         return error;
 849
 850 cleanup_dquot:
 851         DQUOT_FREE_BLOCK(inode, 1);
 852         goto cleanup;
 853
 854 bad_block:
 855         ext3_error(inode->i_sb, __FUNCTION__,
 856                    "inode %lu: bad block "E3FSBLK, inode->i_ino,
 857                    EXT3_I(inode)->i_file_acl);
 858         goto cleanup;
 859
 860 #undef header
 861 }
 862
 863 struct ext3_xattr_ibody_find {
 864         struct ext3_xattr_search s;
 865         struct ext3_iloc iloc;
 866 };
 867
 868 static int
 869 ext3_xattr_ibody_find(struct inode *inode, struct ext3_xattr_info *i,
 870                       struct ext3_xattr_ibody_find *is)
 871 {
 872         struct ext3_xattr_ibody_header *header;
 873         struct ext3_inode *raw_inode;
 874         int error;
 875
 876         if (EXT3_I(inode)->i_extra_isize == 0)
 877                 return 0;
 878         raw_inode = ext3_raw_inode(&is->iloc);
 879         header = IHDR(inode, raw_inode);
 880         is->s.base = is->s.first = IFIRST(header);
 881         is->s.here = is->s.first;
 882         is->s.end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 883         if (EXT3_I(inode)->i_state & EXT3_STATE_XATTR) {
 884                 error = ext3_xattr_check_names(IFIRST(header), is->s.end);
 885                 if (error)
 886                         return error;
 887                 /* Find the named attribute. */
 888                 error = ext3_xattr_find_entry(&is->s.here, i->name_index,
 889                                               i->name, is->s.end -
 890                                               (void *)is->s.base, 0);
 891                 if (error && error != -ENODATA)
 892                         return error;
 893                 is->s.not_found = error;
 894         }
 895         return 0;
 896 }
 897
 898 static int
 899 ext3_xattr_ibody_set(handle_t *handle, struct inode *inode,
 900                      struct ext3_xattr_info *i,
 901                      struct ext3_xattr_ibody_find *is)
 902 {
 903         struct ext3_xattr_ibody_header *header;
 904         struct ext3_xattr_search *s = &is->s;
 905         int error;
 906
 907         if (EXT3_I(inode)->i_extra_isize == 0)
 908                 return -ENOSPC;
 909         error = ext3_xattr_set_entry(i, s);
 910         if (error)
 911                 return error;
 912         header = IHDR(inode, ext3_raw_inode(&is->iloc));
 913         if (!IS_LAST_ENTRY(s->first)) {
 914                 header->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
 915                 EXT3_I(inode)->i_state |= EXT3_STATE_XATTR;
 916         } else {
 917                 header->h_magic = cpu_to_le32(0);
 918                 EXT3_I(inode)->i_state &= ~EXT3_STATE_XATTR;
 919         }
 920         return 0;
 921 }
 922
 923 /*
 924  * ext3_xattr_set_handle()
 925  *
 926  * Create, replace or remove an extended attribute for this inode. Buffer
 927  * is NULL to remove an existing extended attribute, and non-NULL to
 928  * either replace an existing extended attribute, or create a new extended
 929  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 930  * specify that an extended attribute must exist and must not exist
 931  * previous to the call, respectively.
 932  *
 933  * Returns 0, or a negative error number on failure.
 934  */
 935 int
 936 ext3_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
 937                       const char *name, const void *value, size_t value_len,
 938                       int flags)
 939 {
 940         struct ext3_xattr_info i = {
 941                 .name_index = name_index,
 942                 .name = name,
 943                 .value = value,
 944                 .value_len = value_len,
 945
 946         };
 947         struct ext3_xattr_ibody_find is = {
 948                 .s = { .not_found = -ENODATA, },
 949         };
 950         struct ext3_xattr_block_find bs = {
 951                 .s = { .not_found = -ENODATA, },
 952         };
 953         int error;
 954
 955         if (!name)
 956                 return -EINVAL;
 957         if (strlen(name) > 255)
 958                 return -ERANGE;
 959         down_write(&EXT3_I(inode)->xattr_sem);
 960         error = ext3_get_inode_loc(inode, &is.iloc);
 961         if (error)
 962                 goto cleanup;
 963
 964         if (EXT3_I(inode)->i_state & EXT3_STATE_NEW) {
 965                 struct ext3_inode *raw_inode = ext3_raw_inode(&is.iloc);
 966                 memset(raw_inode, 0, EXT3_SB(inode->i_sb)->s_inode_size);
 967                 EXT3_I(inode)->i_state &= ~EXT3_STATE_NEW;
 968         }
 969
 970         error = ext3_xattr_ibody_find(inode, &i, &is);
 971         if (error)
 972                 goto cleanup;
 973         if (is.s.not_found)
 974                 error = ext3_xattr_block_find(inode, &i, &bs);
 975         if (error)
 976                 goto cleanup;
 977         if (is.s.not_found && bs.s.not_found) {
 978                 error = -ENODATA;
 979                 if (flags & XATTR_REPLACE)
 980                         goto cleanup;
 981                 error = 0;
 982                 if (!value)
 983                         goto cleanup;
 984         } else {
 985                 error = -EEXIST;
 986                 if (flags & XATTR_CREATE)
 987                         goto cleanup;
 988         }
 989         error = ext3_journal_get_write_access(handle, is.iloc.bh);
 990         if (error)
 991                 goto cleanup;
 992         if (!value) {
 993                 if (!is.s.not_found)
 994                         error = ext3_xattr_ibody_set(handle, inode, &i, &is);
 995                 else if (!bs.s.not_found)
 996                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
 997         } else {
 998                 error = ext3_xattr_ibody_set(handle, inode, &i, &is);
 999                 if (!error && !bs.s.not_found) {
1000                         i.value = NULL;
1001                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1002                 } else if (error == -ENOSPC) {
1003                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1004                         if (error)
1005                                 goto cleanup;
1006                         if (!is.s.not_found) {
1007                                 i.value = NULL;
1008                                 error = ext3_xattr_ibody_set(handle, inode, &i,
1009                                                              &is);
1010                         }
1011                 }
1012         }
1013         if (!error) {
1014                 ext3_xattr_update_super_block(handle, inode->i_sb);
1015                 inode->i_ctime = CURRENT_TIME_SEC;
1016                 error = ext3_mark_iloc_dirty(handle, inode, &is.iloc);
1017                 /*
1018                  * The bh is consumed by ext3_mark_iloc_dirty, even with
1019                  * error != 0.
1020                  */
1021                 is.iloc.bh = NULL;
1022                 if (IS_SYNC(inode))
1023                         handle->h_sync = 1;
1024         }
1025
1026 cleanup:
1027         brelse(is.iloc.bh);
1028         brelse(bs.bh);
1029         up_write(&EXT3_I(inode)->xattr_sem);
1030         return error;
1031 }
1032
1033 /*
1034  * ext3_xattr_set()
1035  *
1036  * Like ext3_xattr_set_handle, but start from an inode. This extended
1037  * attribute modification is a filesystem transaction by itself.
1038  *
1039  * Returns 0, or a negative error number on failure.
1040  */
1041 int
1042 ext3_xattr_set(struct inode *inode, int name_index, const char *name,
1043                const void *value, size_t value_len, int flags)
1044 {
1045         handle_t *handle;
1046         int error, retries = 0;
1047
1048 retry:
1049         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
1050         if (IS_ERR(handle)) {
1051                 error = PTR_ERR(handle);
1052         } else {
1053                 int error2;
1054
1055                 error = ext3_xattr_set_handle(handle, inode, name_index, name,
1056                                               value, value_len, flags);
1057                 error2 = ext3_journal_stop(handle);
1058                 if (error == -ENOSPC &&
1059                     ext3_should_retry_alloc(inode->i_sb, &retries))
1060                         goto retry;
1061                 if (error == 0)
1062                         error = error2;
1063         }
1064
1065         return error;
1066 }
1067
1068 /*
1069  * ext3_xattr_delete_inode()
1070  *
1071  * Free extended attribute resources associated with this inode. This
1072  * is called immediately before an inode is freed. We have exclusive
1073  * access to the inode.
1074  */
1075 void
1076 ext3_xattr_delete_inode(handle_t *handle, struct inode *inode)
1077 {
1078         struct buffer_head *bh = NULL;
1079
1080         if (!EXT3_I(inode)->i_file_acl)
1081                 goto cleanup;
1082         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
1083         if (!bh) {
1084                 ext3_error(inode->i_sb, __FUNCTION__,
1085                         "inode %lu: block "E3FSBLK" read error", inode->i_ino,
1086                         EXT3_I(inode)->i_file_acl);
1087                 goto cleanup;
1088         }
1089         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
1090             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1091                 ext3_error(inode->i_sb, __FUNCTION__,
1092                         "inode %lu: bad block "E3FSBLK, inode->i_ino,
1093                         EXT3_I(inode)->i_file_acl);
1094                 goto cleanup;
1095         }
1096         ext3_xattr_release_block(handle, inode, bh);
1097         EXT3_I(inode)->i_file_acl = 0;
1098
1099 cleanup:
1100         brelse(bh);
1101 }
1102
1103 /*
1104  * ext3_xattr_put_super()
1105  *
1106  * This is called when a file system is unmounted.
1107  */
1108 void
1109 ext3_xattr_put_super(struct super_block *sb)
1110 {
1111         mb_cache_shrink(sb->s_bdev);
1112 }
1113
1114 /*
1115  * ext3_xattr_cache_insert()
1116  *
1117  * Create a new entry in the extended attribute cache, and insert
1118  * it unless such an entry is already in the cache.
1119  *
1120  * Returns 0, or a negative error number on failure.
1121  */
1122 static void
1123 ext3_xattr_cache_insert(struct buffer_head *bh)
1124 {
1125         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1126         struct mb_cache_entry *ce;
1127         int error;
1128
1129         ce = mb_cache_entry_alloc(ext3_xattr_cache);
1130         if (!ce) {
1131                 ea_bdebug(bh, "out of memory");
1132                 return;
1133         }
1134         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
1135         if (error) {
1136                 mb_cache_entry_free(ce);
1137                 if (error == -EBUSY) {
1138                         ea_bdebug(bh, "already in cache");
1139                         error = 0;
1140                 }
1141         } else {
1142                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1143                 mb_cache_entry_release(ce);
1144         }
1145 }
1146
1147 /*
1148  * ext3_xattr_cmp()
1149  *
1150  * Compare two extended attribute blocks for equality.
1151  *
1152  * Returns 0 if the blocks are equal, 1 if they differ, and
1153  * a negative error number on errors.
1154  */
1155 static int
1156 ext3_xattr_cmp(struct ext3_xattr_header *header1,
1157                struct ext3_xattr_header *header2)
1158 {
1159         struct ext3_xattr_entry *entry1, *entry2;
1160
1161         entry1 = ENTRY(header1+1);
1162         entry2 = ENTRY(header2+1);
1163         while (!IS_LAST_ENTRY(entry1)) {
1164                 if (IS_LAST_ENTRY(entry2))
1165                         return 1;
1166                 if (entry1->e_hash != entry2->e_hash ||
1167                     entry1->e_name_index != entry2->e_name_index ||
1168                     entry1->e_name_len != entry2->e_name_len ||
1169                     entry1->e_value_size != entry2->e_value_size ||
1170                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1171                         return 1;
1172                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1173                         return -EIO;
1174                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1175                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1176                            le32_to_cpu(entry1->e_value_size)))
1177                         return 1;
1178
1179                 entry1 = EXT3_XATTR_NEXT(entry1);
1180                 entry2 = EXT3_XATTR_NEXT(entry2);
1181         }
1182         if (!IS_LAST_ENTRY(entry2))
1183                 return 1;
1184         return 0;
1185 }
1186
1187 /*
1188  * ext3_xattr_cache_find()
1189  *
1190  * Find an identical extended attribute block.
1191  *
1192  * Returns a pointer to the block found, or NULL if such a block was
1193  * not found or an error occurred.
1194  */
1195 static struct buffer_head *
1196 ext3_xattr_cache_find(struct inode *inode, struct ext3_xattr_header *header,
1197                       struct mb_cache_entry **pce)
1198 {
1199         __u32 hash = le32_to_cpu(header->h_hash);
1200         struct mb_cache_entry *ce;
1201
1202         if (!header->h_hash)
1203                 return NULL;  /* never share */
1204         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1205 again:
1206         ce = mb_cache_entry_find_first(ext3_xattr_cache, 0,
1207                                        inode->i_sb->s_bdev, hash);
1208         while (ce) {
1209                 struct buffer_head *bh;
1210
1211                 if (IS_ERR(ce)) {
1212                         if (PTR_ERR(ce) == -EAGAIN)
1213                                 goto again;
1214                         break;
1215                 }
1216                 bh = sb_bread(inode->i_sb, ce->e_block);
1217                 if (!bh) {
1218                         ext3_error(inode->i_sb, __FUNCTION__,
1219                                 "inode %lu: block %lu read error",
1220                                 inode->i_ino, (unsigned long) ce->e_block);
1221                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1222                                 EXT3_XATTR_REFCOUNT_MAX) {
1223                         ea_idebug(inode, "block %lu refcount %d>=%d",
1224                                   (unsigned long) ce->e_block,
1225                                   le32_to_cpu(BHDR(bh)->h_refcount),
1226                                           EXT3_XATTR_REFCOUNT_MAX);
1227                 } else if (ext3_xattr_cmp(header, BHDR(bh)) == 0) {
1228                         *pce = ce;
1229                         return bh;
1230                 }
1231                 brelse(bh);
1232                 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
1233         }
1234         return NULL;
1235 }
1236
1237 #define NAME_HASH_SHIFT 5
1238 #define VALUE_HASH_SHIFT 16
1239
1240 /*
1241  * ext3_xattr_hash_entry()
1242  *
1243  * Compute the hash of an extended attribute.
1244  */
1245 static inline void ext3_xattr_hash_entry(struct ext3_xattr_header *header,
1246                                          struct ext3_xattr_entry *entry)
1247 {
1248         __u32 hash = 0;
1249         char *name = entry->e_name;
1250         int n;
1251
1252         for (n=0; n < entry->e_name_len; n++) {
1253                 hash = (hash << NAME_HASH_SHIFT) ^
1254                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1255                        *name++;
1256         }
1257
1258         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1259                 __le32 *value = (__le32 *)((char *)header +
1260                         le16_to_cpu(entry->e_value_offs));
1261                 for (n = (le32_to_cpu(entry->e_value_size) +
1262                      EXT3_XATTR_ROUND) >> EXT3_XATTR_PAD_BITS; n; n--) {
1263                         hash = (hash << VALUE_HASH_SHIFT) ^
1264                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1265                                le32_to_cpu(*value++);
1266                 }
1267         }
1268         entry->e_hash = cpu_to_le32(hash);
1269 }
1270
1271 #undef NAME_HASH_SHIFT
1272 #undef VALUE_HASH_SHIFT
1273
1274 #define BLOCK_HASH_SHIFT 16
1275
1276 /*
1277  * ext3_xattr_rehash()
1278  *
1279  * Re-compute the extended attribute hash value after an entry has changed.
1280  */
1281 static void ext3_xattr_rehash(struct ext3_xattr_header *header,
1282                               struct ext3_xattr_entry *entry)
1283 {
1284         struct ext3_xattr_entry *here;
1285         __u32 hash = 0;
1286
1287         ext3_xattr_hash_entry(header, entry);
1288         here = ENTRY(header+1);
1289         while (!IS_LAST_ENTRY(here)) {
1290                 if (!here->e_hash) {
1291                         /* Block is not shared if an entry's hash value == 0 */
1292                         hash = 0;
1293                         break;
1294                 }
1295                 hash = (hash << BLOCK_HASH_SHIFT) ^
1296                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1297                        le32_to_cpu(here->e_hash);
1298                 here = EXT3_XATTR_NEXT(here);
1299         }
1300         header->h_hash = cpu_to_le32(hash);
1301 }
1302
1303 #undef BLOCK_HASH_SHIFT
1304
1305 int __init
1306 init_ext3_xattr(void)
1307 {
1308         ext3_xattr_cache = mb_cache_create("ext3_xattr", NULL,
1309                 sizeof(struct mb_cache_entry) +
1310                 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1311         if (!ext3_xattr_cache)
1312                 return -ENOMEM;
1313         return 0;
1314 }
1315
1316 void
1317 exit_ext3_xattr(void)
1318 {
1319         if (ext3_xattr_cache)
1320                 mb_cache_destroy(ext3_xattr_cache);
1321         ext3_xattr_cache = NULL;
1322 }