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