fs/ext3/xattr.c

   1 /*
   2  * linux/fs/ext3/xattr.c
   3  *
   4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   5  *
   6  * Fix by Harrison Xing <harrison@mountainviewdata.com>.
   7  * Ext3 code with a lot of help from Eric Jarman <ejarman@acm.org>.
   8  * Extended attributes for symlinks and special files added per
   9  *  suggestion of Luka Renko <luka.renko@hermes.si>.
  10  * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
  11  *  Red Hat Inc.
  12  * ea-in-inode support by Alex Tomas <alex@clusterfs.com> aka bzzz
  13  *  and Andreas Gruenbacher <agruen@suse.de>.
  14  */
  15
  16 /*
  17  * Extended attributes are stored directly in inodes (on file systems with
  18  * inodes bigger than 128 bytes) and on additional disk blocks. The i_file_acl
  19  * field contains the block number if an inode uses an additional block. All
  20  * attributes must fit in the inode and one additional block. Blocks that
  21  * contain the identical set of attributes may be shared among several inodes.
  22  * Identical blocks are detected by keeping a cache of blocks that have
  23  * recently been accessed.
  24  *
  25  * The attributes in inodes and on blocks have a different header; the entries
  26  * are stored in the same format:
  27  *
  28  *   +------------------+
  29  *   | header           |
  30  *   | entry 1          | |
  31  *   | entry 2          | | growing downwards
  32  *   | entry 3          | v
  33  *   | four null bytes  |
  34  *   | . . .            |
  35  *   | value 1          | ^
  36  *   | value 3          | | growing upwards
  37  *   | value 2          | |
  38  *   +------------------+
  39  *
  40  * The header is followed by multiple entry descriptors. In disk blocks, the
  41  * entry descriptors are kept sorted. In inodes, they are unsorted. The
  42  * attribute values are aligned to the end of the block in no specific order.
  43  *
  44  * Locking strategy
  45  * ----------------
  46  * EXT3_I(inode)->i_file_acl is protected by EXT3_I(inode)->xattr_sem.
  47  * EA blocks are only changed if they are exclusive to an inode, so
  48  * holding xattr_sem also means that nothing but the EA block's reference
  49  * count can change. Multiple writers to the same block are synchronized
  50  * by the buffer lock.
  51  */
  52
  53 #include <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                 BHDR(bh)->h_refcount = cpu_to_le32(
 496                                 le32_to_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                 DQUOT_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, __FUNCTION__,
 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_KERNEL);
 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 = kmalloc(sb->s_blocksize, GFP_KERNEL);
 745                 /* assert(header == s->base) */
 746                 error = -ENOMEM;
 747                 if (s->base == NULL)
 748                         goto cleanup;
 749                 memset(s->base, 0, sb->s_blocksize);
 750                 header(s->base)->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
 751                 header(s->base)->h_blocks = cpu_to_le32(1);
 752                 header(s->base)->h_refcount = cpu_to_le32(1);
 753                 s->first = ENTRY(header(s->base)+1);
 754                 s->here = ENTRY(header(s->base)+1);
 755                 s->end = s->base + sb->s_blocksize;
 756         }
 757
 758         error = ext3_xattr_set_entry(i, s);
 759         if (error == -EIO)
 760                 goto bad_block;
 761         if (error)
 762                 goto cleanup;
 763         if (!IS_LAST_ENTRY(s->first))
 764                 ext3_xattr_rehash(header(s->base), s->here);
 765
 766 inserted:
 767         if (!IS_LAST_ENTRY(s->first)) {
 768                 new_bh = ext3_xattr_cache_find(inode, header(s->base), &ce);
 769                 if (new_bh) {
 770                         /* We found an identical block in the cache. */
 771                         if (new_bh == bs->bh)
 772                                 ea_bdebug(new_bh, "keeping");
 773                         else {
 774                                 /* The old block is released after updating
 775                                    the inode. */
 776                                 error = -EDQUOT;
 777                                 if (DQUOT_ALLOC_BLOCK(inode, 1))
 778                                         goto cleanup;
 779                                 error = ext3_journal_get_write_access(handle,
 780                                                                       new_bh);
 781                                 if (error)
 782                                         goto cleanup_dquot;
 783                                 lock_buffer(new_bh);
 784                                 BHDR(new_bh)->h_refcount = cpu_to_le32(1 +
 785                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 786                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
 787                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 788                                 unlock_buffer(new_bh);
 789                                 error = ext3_journal_dirty_metadata(handle,
 790                                                                     new_bh);
 791                                 if (error)
 792                                         goto cleanup_dquot;
 793                         }
 794                         mb_cache_entry_release(ce);
 795                         ce = NULL;
 796                 } else if (bs->bh && s->base == bs->bh->b_data) {
 797                         /* We were modifying this block in-place. */
 798                         ea_bdebug(bs->bh, "keeping this block");
 799                         new_bh = bs->bh;
 800                         get_bh(new_bh);
 801                 } else {
 802                         /* We need to allocate a new block */
 803                         ext3_fsblk_t goal = le32_to_cpu(
 804                                         EXT3_SB(sb)->s_es->s_first_data_block) +
 805                                 (ext3_fsblk_t)EXT3_I(inode)->i_block_group *
 806                                 EXT3_BLOCKS_PER_GROUP(sb);
 807                         ext3_fsblk_t block = ext3_new_block(handle, inode,
 808                                                         goal, &error);
 809                         if (error)
 810                                 goto cleanup;
 811                         ea_idebug(inode, "creating block %d", block);
 812
 813                         new_bh = sb_getblk(sb, block);
 814                         if (!new_bh) {
 815 getblk_failed:
 816                                 ext3_free_blocks(handle, inode, block, 1);
 817                                 error = -EIO;
 818                                 goto cleanup;
 819                         }
 820                         lock_buffer(new_bh);
 821                         error = ext3_journal_get_create_access(handle, new_bh);
 822                         if (error) {
 823                                 unlock_buffer(new_bh);
 824                                 goto getblk_failed;
 825                         }
 826                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
 827                         set_buffer_uptodate(new_bh);
 828                         unlock_buffer(new_bh);
 829                         ext3_xattr_cache_insert(new_bh);
 830                         error = ext3_journal_dirty_metadata(handle, new_bh);
 831                         if (error)
 832                                 goto cleanup;
 833                 }
 834         }
 835
 836         /* Update the inode. */
 837         EXT3_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
 838
 839         /* Drop the previous xattr block. */
 840         if (bs->bh && bs->bh != new_bh)
 841                 ext3_xattr_release_block(handle, inode, bs->bh);
 842         error = 0;
 843
 844 cleanup:
 845         if (ce)
 846                 mb_cache_entry_release(ce);
 847         brelse(new_bh);
 848         if (!(bs->bh && s->base == bs->bh->b_data))
 849                 kfree(s->base);
 850
 851         return error;
 852
 853 cleanup_dquot:
 854         DQUOT_FREE_BLOCK(inode, 1);
 855         goto cleanup;
 856
 857 bad_block:
 858         ext3_error(inode->i_sb, __FUNCTION__,
 859                    "inode %lu: bad block "E3FSBLK, inode->i_ino,
 860                    EXT3_I(inode)->i_file_acl);
 861         goto cleanup;
 862
 863 #undef header
 864 }
 865
 866 struct ext3_xattr_ibody_find {
 867         struct ext3_xattr_search s;
 868         struct ext3_iloc iloc;
 869 };
 870
 871 static int
 872 ext3_xattr_ibody_find(struct inode *inode, struct ext3_xattr_info *i,
 873                       struct ext3_xattr_ibody_find *is)
 874 {
 875         struct ext3_xattr_ibody_header *header;
 876         struct ext3_inode *raw_inode;
 877         int error;
 878
 879         if (EXT3_I(inode)->i_extra_isize == 0)
 880                 return 0;
 881         raw_inode = ext3_raw_inode(&is->iloc);
 882         header = IHDR(inode, raw_inode);
 883         is->s.base = is->s.first = IFIRST(header);
 884         is->s.here = is->s.first;
 885         is->s.end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 886         if (EXT3_I(inode)->i_state & EXT3_STATE_XATTR) {
 887                 error = ext3_xattr_check_names(IFIRST(header), is->s.end);
 888                 if (error)
 889                         return error;
 890                 /* Find the named attribute. */
 891                 error = ext3_xattr_find_entry(&is->s.here, i->name_index,
 892                                               i->name, is->s.end -
 893                                               (void *)is->s.base, 0);
 894                 if (error && error != -ENODATA)
 895                         return error;
 896                 is->s.not_found = error;
 897         }
 898         return 0;
 899 }
 900
 901 static int
 902 ext3_xattr_ibody_set(handle_t *handle, struct inode *inode,
 903                      struct ext3_xattr_info *i,
 904                      struct ext3_xattr_ibody_find *is)
 905 {
 906         struct ext3_xattr_ibody_header *header;
 907         struct ext3_xattr_search *s = &is->s;
 908         int error;
 909
 910         if (EXT3_I(inode)->i_extra_isize == 0)
 911                 return -ENOSPC;
 912         error = ext3_xattr_set_entry(i, s);
 913         if (error)
 914                 return error;
 915         header = IHDR(inode, ext3_raw_inode(&is->iloc));
 916         if (!IS_LAST_ENTRY(s->first)) {
 917                 header->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
 918                 EXT3_I(inode)->i_state |= EXT3_STATE_XATTR;
 919         } else {
 920                 header->h_magic = cpu_to_le32(0);
 921                 EXT3_I(inode)->i_state &= ~EXT3_STATE_XATTR;
 922         }
 923         return 0;
 924 }
 925
 926 /*
 927  * ext3_xattr_set_handle()
 928  *
 929  * Create, replace or remove an extended attribute for this inode. Buffer
 930  * is NULL to remove an existing extended attribute, and non-NULL to
 931  * either replace an existing extended attribute, or create a new extended
 932  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 933  * specify that an extended attribute must exist and must not exist
 934  * previous to the call, respectively.
 935  *
 936  * Returns 0, or a negative error number on failure.
 937  */
 938 int
 939 ext3_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
 940                       const char *name, const void *value, size_t value_len,
 941                       int flags)
 942 {
 943         struct ext3_xattr_info i = {
 944                 .name_index = name_index,
 945                 .name = name,
 946                 .value = value,
 947                 .value_len = value_len,
 948
 949         };
 950         struct ext3_xattr_ibody_find is = {
 951                 .s = { .not_found = -ENODATA, },
 952         };
 953         struct ext3_xattr_block_find bs = {
 954                 .s = { .not_found = -ENODATA, },
 955         };
 956         int error;
 957
 958         if (!name)
 959                 return -EINVAL;
 960         if (strlen(name) > 255)
 961                 return -ERANGE;
 962         down_write(&EXT3_I(inode)->xattr_sem);
 963         error = ext3_get_inode_loc(inode, &is.iloc);
 964         if (error)
 965                 goto cleanup;
 966
 967         if (EXT3_I(inode)->i_state & EXT3_STATE_NEW) {
 968                 struct ext3_inode *raw_inode = ext3_raw_inode(&is.iloc);
 969                 memset(raw_inode, 0, EXT3_SB(inode->i_sb)->s_inode_size);
 970                 EXT3_I(inode)->i_state &= ~EXT3_STATE_NEW;
 971         }
 972
 973         error = ext3_xattr_ibody_find(inode, &i, &is);
 974         if (error)
 975                 goto cleanup;
 976         if (is.s.not_found)
 977                 error = ext3_xattr_block_find(inode, &i, &bs);
 978         if (error)
 979                 goto cleanup;
 980         if (is.s.not_found && bs.s.not_found) {
 981                 error = -ENODATA;
 982                 if (flags & XATTR_REPLACE)
 983                         goto cleanup;
 984                 error = 0;
 985                 if (!value)
 986                         goto cleanup;
 987         } else {
 988                 error = -EEXIST;
 989                 if (flags & XATTR_CREATE)
 990                         goto cleanup;
 991         }
 992         error = ext3_journal_get_write_access(handle, is.iloc.bh);
 993         if (error)
 994                 goto cleanup;
 995         if (!value) {
 996                 if (!is.s.not_found)
 997                         error = ext3_xattr_ibody_set(handle, inode, &i, &is);
 998                 else if (!bs.s.not_found)
 999                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1000         } else {
1001                 error = ext3_xattr_ibody_set(handle, inode, &i, &is);
1002                 if (!error && !bs.s.not_found) {
1003                         i.value = NULL;
1004                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1005                 } else if (error == -ENOSPC) {
1006                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1007                         if (error)
1008                                 goto cleanup;
1009                         if (!is.s.not_found) {
1010                                 i.value = NULL;
1011                                 error = ext3_xattr_ibody_set(handle, inode, &i,
1012                                                              &is);
1013                         }
1014                 }
1015         }
1016         if (!error) {
1017                 ext3_xattr_update_super_block(handle, inode->i_sb);
1018                 inode->i_ctime = CURRENT_TIME_SEC;
1019                 error = ext3_mark_iloc_dirty(handle, inode, &is.iloc);
1020                 /*
1021                  * The bh is consumed by ext3_mark_iloc_dirty, even with
1022                  * error != 0.
1023                  */
1024                 is.iloc.bh = NULL;
1025                 if (IS_SYNC(inode))
1026                         handle->h_sync = 1;
1027         }
1028
1029 cleanup:
1030         brelse(is.iloc.bh);
1031         brelse(bs.bh);
1032         up_write(&EXT3_I(inode)->xattr_sem);
1033         return error;
1034 }
1035
1036 /*
1037  * ext3_xattr_set()
1038  *
1039  * Like ext3_xattr_set_handle, but start from an inode. This extended
1040  * attribute modification is a filesystem transaction by itself.
1041  *
1042  * Returns 0, or a negative error number on failure.
1043  */
1044 int
1045 ext3_xattr_set(struct inode *inode, int name_index, const char *name,
1046                const void *value, size_t value_len, int flags)
1047 {
1048         handle_t *handle;
1049         int error, retries = 0;
1050
1051 retry:
1052         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
1053         if (IS_ERR(handle)) {
1054                 error = PTR_ERR(handle);
1055         } else {
1056                 int error2;
1057
1058                 error = ext3_xattr_set_handle(handle, inode, name_index, name,
1059                                               value, value_len, flags);
1060                 error2 = ext3_journal_stop(handle);
1061                 if (error == -ENOSPC &&
1062                     ext3_should_retry_alloc(inode->i_sb, &retries))
1063                         goto retry;
1064                 if (error == 0)
1065                         error = error2;
1066         }
1067
1068         return error;
1069 }
1070
1071 /*
1072  * ext3_xattr_delete_inode()
1073  *
1074  * Free extended attribute resources associated with this inode. This
1075  * is called immediately before an inode is freed. We have exclusive
1076  * access to the inode.
1077  */
1078 void
1079 ext3_xattr_delete_inode(handle_t *handle, struct inode *inode)
1080 {
1081         struct buffer_head *bh = NULL;
1082
1083         if (!EXT3_I(inode)->i_file_acl)
1084                 goto cleanup;
1085         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
1086         if (!bh) {
1087                 ext3_error(inode->i_sb, __FUNCTION__,
1088                         "inode %lu: block "E3FSBLK" read error", inode->i_ino,
1089                         EXT3_I(inode)->i_file_acl);
1090                 goto cleanup;
1091         }
1092         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
1093             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1094                 ext3_error(inode->i_sb, __FUNCTION__,
1095                         "inode %lu: bad block "E3FSBLK, inode->i_ino,
1096                         EXT3_I(inode)->i_file_acl);
1097                 goto cleanup;
1098         }
1099         ext3_xattr_release_block(handle, inode, bh);
1100         EXT3_I(inode)->i_file_acl = 0;
1101
1102 cleanup:
1103         brelse(bh);
1104 }
1105
1106 /*
1107  * ext3_xattr_put_super()
1108  *
1109  * This is called when a file system is unmounted.
1110  */
1111 void
1112 ext3_xattr_put_super(struct super_block *sb)
1113 {
1114         mb_cache_shrink(sb->s_bdev);
1115 }
1116
1117 /*
1118  * ext3_xattr_cache_insert()
1119  *
1120  * Create a new entry in the extended attribute cache, and insert
1121  * it unless such an entry is already in the cache.
1122  *
1123  * Returns 0, or a negative error number on failure.
1124  */
1125 static void
1126 ext3_xattr_cache_insert(struct buffer_head *bh)
1127 {
1128         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1129         struct mb_cache_entry *ce;
1130         int error;
1131
1132         ce = mb_cache_entry_alloc(ext3_xattr_cache);
1133         if (!ce) {
1134                 ea_bdebug(bh, "out of memory");
1135                 return;
1136         }
1137         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
1138         if (error) {
1139                 mb_cache_entry_free(ce);
1140                 if (error == -EBUSY) {
1141                         ea_bdebug(bh, "already in cache");
1142                         error = 0;
1143                 }
1144         } else {
1145                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1146                 mb_cache_entry_release(ce);
1147         }
1148 }
1149
1150 /*
1151  * ext3_xattr_cmp()
1152  *
1153  * Compare two extended attribute blocks for equality.
1154  *
1155  * Returns 0 if the blocks are equal, 1 if they differ, and
1156  * a negative error number on errors.
1157  */
1158 static int
1159 ext3_xattr_cmp(struct ext3_xattr_header *header1,
1160                struct ext3_xattr_header *header2)
1161 {
1162         struct ext3_xattr_entry *entry1, *entry2;
1163
1164         entry1 = ENTRY(header1+1);
1165         entry2 = ENTRY(header2+1);
1166         while (!IS_LAST_ENTRY(entry1)) {
1167                 if (IS_LAST_ENTRY(entry2))
1168                         return 1;
1169                 if (entry1->e_hash != entry2->e_hash ||
1170                     entry1->e_name_index != entry2->e_name_index ||
1171                     entry1->e_name_len != entry2->e_name_len ||
1172                     entry1->e_value_size != entry2->e_value_size ||
1173                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1174                         return 1;
1175                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1176                         return -EIO;
1177                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1178                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1179                            le32_to_cpu(entry1->e_value_size)))
1180                         return 1;
1181
1182                 entry1 = EXT3_XATTR_NEXT(entry1);
1183                 entry2 = EXT3_XATTR_NEXT(entry2);
1184         }
1185         if (!IS_LAST_ENTRY(entry2))
1186                 return 1;
1187         return 0;
1188 }
1189
1190 /*
1191  * ext3_xattr_cache_find()
1192  *
1193  * Find an identical extended attribute block.
1194  *
1195  * Returns a pointer to the block found, or NULL if such a block was
1196  * not found or an error occurred.
1197  */
1198 static struct buffer_head *
1199 ext3_xattr_cache_find(struct inode *inode, struct ext3_xattr_header *header,
1200                       struct mb_cache_entry **pce)
1201 {
1202         __u32 hash = le32_to_cpu(header->h_hash);
1203         struct mb_cache_entry *ce;
1204
1205         if (!header->h_hash)
1206                 return NULL;  /* never share */
1207         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1208 again:
1209         ce = mb_cache_entry_find_first(ext3_xattr_cache, 0,
1210                                        inode->i_sb->s_bdev, hash);
1211         while (ce) {
1212                 struct buffer_head *bh;
1213
1214                 if (IS_ERR(ce)) {
1215                         if (PTR_ERR(ce) == -EAGAIN)
1216                                 goto again;
1217                         break;
1218                 }
1219                 bh = sb_bread(inode->i_sb, ce->e_block);
1220                 if (!bh) {
1221                         ext3_error(inode->i_sb, __FUNCTION__,
1222                                 "inode %lu: block %lu read error",
1223                                 inode->i_ino, (unsigned long) ce->e_block);
1224                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1225                                 EXT3_XATTR_REFCOUNT_MAX) {
1226                         ea_idebug(inode, "block %lu refcount %d>=%d",
1227                                   (unsigned long) ce->e_block,
1228                                   le32_to_cpu(BHDR(bh)->h_refcount),
1229                                           EXT3_XATTR_REFCOUNT_MAX);
1230                 } else if (ext3_xattr_cmp(header, BHDR(bh)) == 0) {
1231                         *pce = ce;
1232                         return bh;
1233                 }
1234                 brelse(bh);
1235                 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
1236         }
1237         return NULL;
1238 }
1239
1240 #define NAME_HASH_SHIFT 5
1241 #define VALUE_HASH_SHIFT 16
1242
1243 /*
1244  * ext3_xattr_hash_entry()
1245  *
1246  * Compute the hash of an extended attribute.
1247  */
1248 static inline void ext3_xattr_hash_entry(struct ext3_xattr_header *header,
1249                                          struct ext3_xattr_entry *entry)
1250 {
1251         __u32 hash = 0;
1252         char *name = entry->e_name;
1253         int n;
1254
1255         for (n=0; n < entry->e_name_len; n++) {
1256                 hash = (hash << NAME_HASH_SHIFT) ^
1257                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1258                        *name++;
1259         }
1260
1261         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1262                 __le32 *value = (__le32 *)((char *)header +
1263                         le16_to_cpu(entry->e_value_offs));
1264                 for (n = (le32_to_cpu(entry->e_value_size) +
1265                      EXT3_XATTR_ROUND) >> EXT3_XATTR_PAD_BITS; n; n--) {
1266                         hash = (hash << VALUE_HASH_SHIFT) ^
1267                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1268                                le32_to_cpu(*value++);
1269                 }
1270         }
1271         entry->e_hash = cpu_to_le32(hash);
1272 }
1273
1274 #undef NAME_HASH_SHIFT
1275 #undef VALUE_HASH_SHIFT
1276
1277 #define BLOCK_HASH_SHIFT 16
1278
1279 /*
1280  * ext3_xattr_rehash()
1281  *
1282  * Re-compute the extended attribute hash value after an entry has changed.
1283  */
1284 static void ext3_xattr_rehash(struct ext3_xattr_header *header,
1285                               struct ext3_xattr_entry *entry)
1286 {
1287         struct ext3_xattr_entry *here;
1288         __u32 hash = 0;
1289
1290         ext3_xattr_hash_entry(header, entry);
1291         here = ENTRY(header+1);
1292         while (!IS_LAST_ENTRY(here)) {
1293                 if (!here->e_hash) {
1294                         /* Block is not shared if an entry's hash value == 0 */
1295                         hash = 0;
1296                         break;
1297                 }
1298                 hash = (hash << BLOCK_HASH_SHIFT) ^
1299                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1300                        le32_to_cpu(here->e_hash);
1301                 here = EXT3_XATTR_NEXT(here);
1302         }
1303         header->h_hash = cpu_to_le32(hash);
1304 }
1305
1306 #undef BLOCK_HASH_SHIFT
1307
1308 int __init
1309 init_ext3_xattr(void)
1310 {
1311         ext3_xattr_cache = mb_cache_create("ext3_xattr", NULL,
1312                 sizeof(struct mb_cache_entry) +
1313                 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1314         if (!ext3_xattr_cache)
1315                 return -ENOMEM;
1316         return 0;
1317 }
1318
1319 void
1320 exit_ext3_xattr(void)
1321 {
1322         if (ext3_xattr_cache)
1323                 mb_cache_destroy(ext3_xattr_cache);
1324         ext3_xattr_cache = NULL;
1325 }