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 static int ext3_xattr_list(struct dentry *dentry, char *buffer,
 103                            size_t buffer_size);
 104
 105 static struct mb_cache *ext3_xattr_cache;
 106
 107 static const struct xattr_handler *ext3_xattr_handler_map[] = {
 108         [EXT3_XATTR_INDEX_USER]              = &ext3_xattr_user_handler,
 109 #ifdef CONFIG_EXT3_FS_POSIX_ACL
 110         [EXT3_XATTR_INDEX_POSIX_ACL_ACCESS]  = &ext3_xattr_acl_access_handler,
 111         [EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext3_xattr_acl_default_handler,
 112 #endif
 113         [EXT3_XATTR_INDEX_TRUSTED]           = &ext3_xattr_trusted_handler,
 114 #ifdef CONFIG_EXT3_FS_SECURITY
 115         [EXT3_XATTR_INDEX_SECURITY]          = &ext3_xattr_security_handler,
 116 #endif
 117 };
 118
 119 const struct xattr_handler *ext3_xattr_handlers[] = {
 120         &ext3_xattr_user_handler,
 121         &ext3_xattr_trusted_handler,
 122 #ifdef CONFIG_EXT3_FS_POSIX_ACL
 123         &ext3_xattr_acl_access_handler,
 124         &ext3_xattr_acl_default_handler,
 125 #endif
 126 #ifdef CONFIG_EXT3_FS_SECURITY
 127         &ext3_xattr_security_handler,
 128 #endif
 129         NULL
 130 };
 131
 132 static inline const struct xattr_handler *
 133 ext3_xattr_handler(int name_index)
 134 {
 135         const struct xattr_handler *handler = NULL;
 136
 137         if (name_index > 0 && name_index < ARRAY_SIZE(ext3_xattr_handler_map))
 138                 handler = ext3_xattr_handler_map[name_index];
 139         return handler;
 140 }
 141
 142 /*
 143  * Inode operation listxattr()
 144  *
 145  * dentry->d_inode->i_mutex: don't care
 146  */
 147 ssize_t
 148 ext3_listxattr(struct dentry *dentry, char *buffer, size_t size)
 149 {
 150         return ext3_xattr_list(dentry, buffer, size);
 151 }
 152
 153 static int
 154 ext3_xattr_check_names(struct ext3_xattr_entry *entry, void *end)
 155 {
 156         while (!IS_LAST_ENTRY(entry)) {
 157                 struct ext3_xattr_entry *next = EXT3_XATTR_NEXT(entry);
 158                 if ((void *)next >= end)
 159                         return -EIO;
 160                 entry = next;
 161         }
 162         return 0;
 163 }
 164
 165 static inline int
 166 ext3_xattr_check_block(struct buffer_head *bh)
 167 {
 168         int error;
 169
 170         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
 171             BHDR(bh)->h_blocks != cpu_to_le32(1))
 172                 return -EIO;
 173         error = ext3_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
 174         return error;
 175 }
 176
 177 static inline int
 178 ext3_xattr_check_entry(struct ext3_xattr_entry *entry, size_t size)
 179 {
 180         size_t value_size = le32_to_cpu(entry->e_value_size);
 181
 182         if (entry->e_value_block != 0 || value_size > size ||
 183             le16_to_cpu(entry->e_value_offs) + value_size > size)
 184                 return -EIO;
 185         return 0;
 186 }
 187
 188 static int
 189 ext3_xattr_find_entry(struct ext3_xattr_entry **pentry, int name_index,
 190                       const char *name, size_t size, int sorted)
 191 {
 192         struct ext3_xattr_entry *entry;
 193         size_t name_len;
 194         int cmp = 1;
 195
 196         if (name == NULL)
 197                 return -EINVAL;
 198         name_len = strlen(name);
 199         entry = *pentry;
 200         for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
 201                 cmp = name_index - entry->e_name_index;
 202                 if (!cmp)
 203                         cmp = name_len - entry->e_name_len;
 204                 if (!cmp)
 205                         cmp = memcmp(name, entry->e_name, name_len);
 206                 if (cmp <= 0 && (sorted || cmp == 0))
 207                         break;
 208         }
 209         *pentry = entry;
 210         if (!cmp && ext3_xattr_check_entry(entry, size))
 211                         return -EIO;
 212         return cmp ? -ENODATA : 0;
 213 }
 214
 215 static int
 216 ext3_xattr_block_get(struct inode *inode, int name_index, const char *name,
 217                      void *buffer, size_t buffer_size)
 218 {
 219         struct buffer_head *bh = NULL;
 220         struct ext3_xattr_entry *entry;
 221         size_t size;
 222         int error;
 223
 224         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 225                   name_index, name, buffer, (long)buffer_size);
 226
 227         error = -ENODATA;
 228         if (!EXT3_I(inode)->i_file_acl)
 229                 goto cleanup;
 230         ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
 231         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
 232         if (!bh)
 233                 goto cleanup;
 234         ea_bdebug(bh, "b_count=%d, refcount=%d",
 235                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 236         if (ext3_xattr_check_block(bh)) {
 237 bad_block:      ext3_error(inode->i_sb, __func__,
 238                            "inode %lu: bad block "E3FSBLK, inode->i_ino,
 239                            EXT3_I(inode)->i_file_acl);
 240                 error = -EIO;
 241                 goto cleanup;
 242         }
 243         ext3_xattr_cache_insert(bh);
 244         entry = BFIRST(bh);
 245         error = ext3_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
 246         if (error == -EIO)
 247                 goto bad_block;
 248         if (error)
 249                 goto cleanup;
 250         size = le32_to_cpu(entry->e_value_size);
 251         if (buffer) {
 252                 error = -ERANGE;
 253                 if (size > buffer_size)
 254                         goto cleanup;
 255                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
 256                        size);
 257         }
 258         error = size;
 259
 260 cleanup:
 261         brelse(bh);
 262         return error;
 263 }
 264
 265 static int
 266 ext3_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 267                      void *buffer, size_t buffer_size)
 268 {
 269         struct ext3_xattr_ibody_header *header;
 270         struct ext3_xattr_entry *entry;
 271         struct ext3_inode *raw_inode;
 272         struct ext3_iloc iloc;
 273         size_t size;
 274         void *end;
 275         int error;
 276
 277         if (!ext3_test_inode_state(inode, EXT3_STATE_XATTR))
 278                 return -ENODATA;
 279         error = ext3_get_inode_loc(inode, &iloc);
 280         if (error)
 281                 return error;
 282         raw_inode = ext3_raw_inode(&iloc);
 283         header = IHDR(inode, raw_inode);
 284         entry = IFIRST(header);
 285         end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 286         error = ext3_xattr_check_names(entry, end);
 287         if (error)
 288                 goto cleanup;
 289         error = ext3_xattr_find_entry(&entry, name_index, name,
 290                                       end - (void *)entry, 0);
 291         if (error)
 292                 goto cleanup;
 293         size = le32_to_cpu(entry->e_value_size);
 294         if (buffer) {
 295                 error = -ERANGE;
 296                 if (size > buffer_size)
 297                         goto cleanup;
 298                 memcpy(buffer, (void *)IFIRST(header) +
 299                        le16_to_cpu(entry->e_value_offs), size);
 300         }
 301         error = size;
 302
 303 cleanup:
 304         brelse(iloc.bh);
 305         return error;
 306 }
 307
 308 /*
 309  * ext3_xattr_get()
 310  *
 311  * Copy an extended attribute into the buffer
 312  * provided, or compute the buffer size required.
 313  * Buffer is NULL to compute the size of the buffer required.
 314  *
 315  * Returns a negative error number on failure, or the number of bytes
 316  * used / required on success.
 317  */
 318 int
 319 ext3_xattr_get(struct inode *inode, int name_index, const char *name,
 320                void *buffer, size_t buffer_size)
 321 {
 322         int error;
 323
 324         down_read(&EXT3_I(inode)->xattr_sem);
 325         error = ext3_xattr_ibody_get(inode, name_index, name, buffer,
 326                                      buffer_size);
 327         if (error == -ENODATA)
 328                 error = ext3_xattr_block_get(inode, name_index, name, buffer,
 329                                              buffer_size);
 330         up_read(&EXT3_I(inode)->xattr_sem);
 331         return error;
 332 }
 333
 334 static int
 335 ext3_xattr_list_entries(struct dentry *dentry, struct ext3_xattr_entry *entry,
 336                         char *buffer, size_t buffer_size)
 337 {
 338         size_t rest = buffer_size;
 339
 340         for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
 341                 const struct xattr_handler *handler =
 342                         ext3_xattr_handler(entry->e_name_index);
 343
 344                 if (handler) {
 345                         size_t size = handler->list(dentry, buffer, rest,
 346                                                     entry->e_name,
 347                                                     entry->e_name_len,
 348                                                     handler->flags);
 349                         if (buffer) {
 350                                 if (size > rest)
 351                                         return -ERANGE;
 352                                 buffer += size;
 353                         }
 354                         rest -= size;
 355                 }
 356         }
 357         return buffer_size - rest;
 358 }
 359
 360 static int
 361 ext3_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 362 {
 363         struct inode *inode = dentry->d_inode;
 364         struct buffer_head *bh = NULL;
 365         int error;
 366
 367         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 368                   buffer, (long)buffer_size);
 369
 370         error = 0;
 371         if (!EXT3_I(inode)->i_file_acl)
 372                 goto cleanup;
 373         ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
 374         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
 375         error = -EIO;
 376         if (!bh)
 377                 goto cleanup;
 378         ea_bdebug(bh, "b_count=%d, refcount=%d",
 379                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 380         if (ext3_xattr_check_block(bh)) {
 381                 ext3_error(inode->i_sb, __func__,
 382                            "inode %lu: bad block "E3FSBLK, inode->i_ino,
 383                            EXT3_I(inode)->i_file_acl);
 384                 error = -EIO;
 385                 goto cleanup;
 386         }
 387         ext3_xattr_cache_insert(bh);
 388         error = ext3_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
 389
 390 cleanup:
 391         brelse(bh);
 392
 393         return error;
 394 }
 395
 396 static int
 397 ext3_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 398 {
 399         struct inode *inode = dentry->d_inode;
 400         struct ext3_xattr_ibody_header *header;
 401         struct ext3_inode *raw_inode;
 402         struct ext3_iloc iloc;
 403         void *end;
 404         int error;
 405
 406         if (!ext3_test_inode_state(inode, EXT3_STATE_XATTR))
 407                 return 0;
 408         error = ext3_get_inode_loc(inode, &iloc);
 409         if (error)
 410                 return error;
 411         raw_inode = ext3_raw_inode(&iloc);
 412         header = IHDR(inode, raw_inode);
 413         end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 414         error = ext3_xattr_check_names(IFIRST(header), end);
 415         if (error)
 416                 goto cleanup;
 417         error = ext3_xattr_list_entries(dentry, IFIRST(header),
 418                                         buffer, buffer_size);
 419
 420 cleanup:
 421         brelse(iloc.bh);
 422         return error;
 423 }
 424
 425 /*
 426  * ext3_xattr_list()
 427  *
 428  * Copy a list of attribute names into the buffer
 429  * provided, or compute the buffer size required.
 430  * Buffer is NULL to compute the size of the buffer required.
 431  *
 432  * Returns a negative error number on failure, or the number of bytes
 433  * used / required on success.
 434  */
 435 static int
 436 ext3_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 437 {
 438         int i_error, b_error;
 439
 440         down_read(&EXT3_I(dentry->d_inode)->xattr_sem);
 441         i_error = ext3_xattr_ibody_list(dentry, buffer, buffer_size);
 442         if (i_error < 0) {
 443                 b_error = 0;
 444         } else {
 445                 if (buffer) {
 446                         buffer += i_error;
 447                         buffer_size -= i_error;
 448                 }
 449                 b_error = ext3_xattr_block_list(dentry, buffer, buffer_size);
 450                 if (b_error < 0)
 451                         i_error = 0;
 452         }
 453         up_read(&EXT3_I(dentry->d_inode)->xattr_sem);
 454         return i_error + b_error;
 455 }
 456
 457 /*
 458  * If the EXT3_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 459  * not set, set it.
 460  */
 461 static void ext3_xattr_update_super_block(handle_t *handle,
 462                                           struct super_block *sb)
 463 {
 464         if (EXT3_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR))
 465                 return;
 466
 467         if (ext3_journal_get_write_access(handle, EXT3_SB(sb)->s_sbh) == 0) {
 468                 EXT3_SET_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR);
 469                 ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
 470         }
 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         int error = 0;
 483
 484         ce = mb_cache_entry_get(ext3_xattr_cache, bh->b_bdev, bh->b_blocknr);
 485         error = ext3_journal_get_write_access(handle, bh);
 486         if (error)
 487                  goto out;
 488
 489         lock_buffer(bh);
 490
 491         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
 492                 ea_bdebug(bh, "refcount now=0; freeing");
 493                 if (ce)
 494                         mb_cache_entry_free(ce);
 495                 ext3_free_blocks(handle, inode, bh->b_blocknr, 1);
 496                 get_bh(bh);
 497                 ext3_forget(handle, 1, inode, bh, bh->b_blocknr);
 498         } else {
 499                 le32_add_cpu(&BHDR(bh)->h_refcount, -1);
 500                 error = ext3_journal_dirty_metadata(handle, bh);
 501                 if (IS_SYNC(inode))
 502                         handle->h_sync = 1;
 503                 dquot_free_block(inode, 1);
 504                 ea_bdebug(bh, "refcount now=%d; releasing",
 505                           le32_to_cpu(BHDR(bh)->h_refcount));
 506                 if (ce)
 507                         mb_cache_entry_release(ce);
 508         }
 509         unlock_buffer(bh);
 510 out:
 511         ext3_std_error(inode->i_sb, error);
 512         return;
 513 }
 514
 515 struct ext3_xattr_info {
 516         int name_index;
 517         const char *name;
 518         const void *value;
 519         size_t value_len;
 520 };
 521
 522 struct ext3_xattr_search {
 523         struct ext3_xattr_entry *first;
 524         void *base;
 525         void *end;
 526         struct ext3_xattr_entry *here;
 527         int not_found;
 528 };
 529
 530 static int
 531 ext3_xattr_set_entry(struct ext3_xattr_info *i, struct ext3_xattr_search *s)
 532 {
 533         struct ext3_xattr_entry *last;
 534         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
 535
 536         /* Compute min_offs and last. */
 537         last = s->first;
 538         for (; !IS_LAST_ENTRY(last); last = EXT3_XATTR_NEXT(last)) {
 539                 if (!last->e_value_block && last->e_value_size) {
 540                         size_t offs = le16_to_cpu(last->e_value_offs);
 541                         if (offs < min_offs)
 542                                 min_offs = offs;
 543                 }
 544         }
 545         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
 546         if (!s->not_found) {
 547                 if (!s->here->e_value_block && s->here->e_value_size) {
 548                         size_t size = le32_to_cpu(s->here->e_value_size);
 549                         free += EXT3_XATTR_SIZE(size);
 550                 }
 551                 free += EXT3_XATTR_LEN(name_len);
 552         }
 553         if (i->value) {
 554                 if (free < EXT3_XATTR_SIZE(i->value_len) ||
 555                     free < EXT3_XATTR_LEN(name_len) +
 556                            EXT3_XATTR_SIZE(i->value_len))
 557                         return -ENOSPC;
 558         }
 559
 560         if (i->value && s->not_found) {
 561                 /* Insert the new name. */
 562                 size_t size = EXT3_XATTR_LEN(name_len);
 563                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
 564                 memmove((void *)s->here + size, s->here, rest);
 565                 memset(s->here, 0, size);
 566                 s->here->e_name_index = i->name_index;
 567                 s->here->e_name_len = name_len;
 568                 memcpy(s->here->e_name, i->name, name_len);
 569         } else {
 570                 if (!s->here->e_value_block && s->here->e_value_size) {
 571                         void *first_val = s->base + min_offs;
 572                         size_t offs = le16_to_cpu(s->here->e_value_offs);
 573                         void *val = s->base + offs;
 574                         size_t size = EXT3_XATTR_SIZE(
 575                                 le32_to_cpu(s->here->e_value_size));
 576
 577                         if (i->value && size == EXT3_XATTR_SIZE(i->value_len)) {
 578                                 /* The old and the new value have the same
 579                                    size. Just replace. */
 580                                 s->here->e_value_size =
 581                                         cpu_to_le32(i->value_len);
 582                                 memset(val + size - EXT3_XATTR_PAD, 0,
 583                                        EXT3_XATTR_PAD); /* Clear pad bytes. */
 584                                 memcpy(val, i->value, i->value_len);
 585                                 return 0;
 586                         }
 587
 588                         /* Remove the old value. */
 589                         memmove(first_val + size, first_val, val - first_val);
 590                         memset(first_val, 0, size);
 591                         s->here->e_value_size = 0;
 592                         s->here->e_value_offs = 0;
 593                         min_offs += size;
 594
 595                         /* Adjust all value offsets. */
 596                         last = s->first;
 597                         while (!IS_LAST_ENTRY(last)) {
 598                                 size_t o = le16_to_cpu(last->e_value_offs);
 599                                 if (!last->e_value_block &&
 600                                     last->e_value_size && o < offs)
 601                                         last->e_value_offs =
 602                                                 cpu_to_le16(o + size);
 603                                 last = EXT3_XATTR_NEXT(last);
 604                         }
 605                 }
 606                 if (!i->value) {
 607                         /* Remove the old name. */
 608                         size_t size = EXT3_XATTR_LEN(name_len);
 609                         last = ENTRY((void *)last - size);
 610                         memmove(s->here, (void *)s->here + size,
 611                                 (void *)last - (void *)s->here + sizeof(__u32));
 612                         memset(last, 0, size);
 613                 }
 614         }
 615
 616         if (i->value) {
 617                 /* Insert the new value. */
 618                 s->here->e_value_size = cpu_to_le32(i->value_len);
 619                 if (i->value_len) {
 620                         size_t size = EXT3_XATTR_SIZE(i->value_len);
 621                         void *val = s->base + min_offs - size;
 622                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
 623                         memset(val + size - EXT3_XATTR_PAD, 0,
 624                                EXT3_XATTR_PAD); /* Clear the pad bytes. */
 625                         memcpy(val, i->value, i->value_len);
 626                 }
 627         }
 628         return 0;
 629 }
 630
 631 struct ext3_xattr_block_find {
 632         struct ext3_xattr_search s;
 633         struct buffer_head *bh;
 634 };
 635
 636 static int
 637 ext3_xattr_block_find(struct inode *inode, struct ext3_xattr_info *i,
 638                       struct ext3_xattr_block_find *bs)
 639 {
 640         struct super_block *sb = inode->i_sb;
 641         int error;
 642
 643         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
 644                   i->name_index, i->name, i->value, (long)i->value_len);
 645
 646         if (EXT3_I(inode)->i_file_acl) {
 647                 /* The inode already has an extended attribute block. */
 648                 bs->bh = sb_bread(sb, EXT3_I(inode)->i_file_acl);
 649                 error = -EIO;
 650                 if (!bs->bh)
 651                         goto cleanup;
 652                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
 653                         atomic_read(&(bs->bh->b_count)),
 654                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
 655                 if (ext3_xattr_check_block(bs->bh)) {
 656                         ext3_error(sb, __func__,
 657                                 "inode %lu: bad block "E3FSBLK, inode->i_ino,
 658                                 EXT3_I(inode)->i_file_acl);
 659                         error = -EIO;
 660                         goto cleanup;
 661                 }
 662                 /* Find the named attribute. */
 663                 bs->s.base = BHDR(bs->bh);
 664                 bs->s.first = BFIRST(bs->bh);
 665                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
 666                 bs->s.here = bs->s.first;
 667                 error = ext3_xattr_find_entry(&bs->s.here, i->name_index,
 668                                               i->name, bs->bh->b_size, 1);
 669                 if (error && error != -ENODATA)
 670                         goto cleanup;
 671                 bs->s.not_found = error;
 672         }
 673         error = 0;
 674
 675 cleanup:
 676         return error;
 677 }
 678
 679 static int
 680 ext3_xattr_block_set(handle_t *handle, struct inode *inode,
 681                      struct ext3_xattr_info *i,
 682                      struct ext3_xattr_block_find *bs)
 683 {
 684         struct super_block *sb = inode->i_sb;
 685         struct buffer_head *new_bh = NULL;
 686         struct ext3_xattr_search *s = &bs->s;
 687         struct mb_cache_entry *ce = NULL;
 688         int error = 0;
 689
 690 #define header(x) ((struct ext3_xattr_header *)(x))
 691
 692         if (i->value && i->value_len > sb->s_blocksize)
 693                 return -ENOSPC;
 694         if (s->base) {
 695                 ce = mb_cache_entry_get(ext3_xattr_cache, bs->bh->b_bdev,
 696                                         bs->bh->b_blocknr);
 697                 error = ext3_journal_get_write_access(handle, bs->bh);
 698                 if (error)
 699                         goto cleanup;
 700                 lock_buffer(bs->bh);
 701
 702                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 703                         if (ce) {
 704                                 mb_cache_entry_free(ce);
 705                                 ce = NULL;
 706                         }
 707                         ea_bdebug(bs->bh, "modifying in-place");
 708                         error = ext3_xattr_set_entry(i, s);
 709                         if (!error) {
 710                                 if (!IS_LAST_ENTRY(s->first))
 711                                         ext3_xattr_rehash(header(s->base),
 712                                                           s->here);
 713                                 ext3_xattr_cache_insert(bs->bh);
 714                         }
 715                         unlock_buffer(bs->bh);
 716                         if (error == -EIO)
 717                                 goto bad_block;
 718                         if (!error)
 719                                 error = ext3_journal_dirty_metadata(handle,
 720                                                                     bs->bh);
 721                         if (error)
 722                                 goto cleanup;
 723                         goto inserted;
 724                 } else {
 725                         int offset = (char *)s->here - bs->bh->b_data;
 726
 727                         unlock_buffer(bs->bh);
 728                         journal_release_buffer(handle, bs->bh);
 729
 730                         if (ce) {
 731                                 mb_cache_entry_release(ce);
 732                                 ce = NULL;
 733                         }
 734                         ea_bdebug(bs->bh, "cloning");
 735                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
 736                         error = -ENOMEM;
 737                         if (s->base == NULL)
 738                                 goto cleanup;
 739                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 740                         s->first = ENTRY(header(s->base)+1);
 741                         header(s->base)->h_refcount = cpu_to_le32(1);
 742                         s->here = ENTRY(s->base + offset);
 743                         s->end = s->base + bs->bh->b_size;
 744                 }
 745         } else {
 746                 /* Allocate a buffer where we construct the new block. */
 747                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
 748                 /* assert(header == s->base) */
 749                 error = -ENOMEM;
 750                 if (s->base == NULL)
 751                         goto cleanup;
 752                 header(s->base)->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
 753                 header(s->base)->h_blocks = cpu_to_le32(1);
 754                 header(s->base)->h_refcount = cpu_to_le32(1);
 755                 s->first = ENTRY(header(s->base)+1);
 756                 s->here = ENTRY(header(s->base)+1);
 757                 s->end = s->base + sb->s_blocksize;
 758         }
 759
 760         error = ext3_xattr_set_entry(i, s);
 761         if (error == -EIO)
 762                 goto bad_block;
 763         if (error)
 764                 goto cleanup;
 765         if (!IS_LAST_ENTRY(s->first))
 766                 ext3_xattr_rehash(header(s->base), s->here);
 767
 768 inserted:
 769         if (!IS_LAST_ENTRY(s->first)) {
 770                 new_bh = ext3_xattr_cache_find(inode, header(s->base), &ce);
 771                 if (new_bh) {
 772                         /* We found an identical block in the cache. */
 773                         if (new_bh == bs->bh)
 774                                 ea_bdebug(new_bh, "keeping");
 775                         else {
 776                                 /* The old block is released after updating
 777                                    the inode. */
 778                                 error = dquot_alloc_block(inode, 1);
 779                                 if (error)
 780                                         goto cleanup;
 781                                 error = ext3_journal_get_write_access(handle,
 782                                                                       new_bh);
 783                                 if (error)
 784                                         goto cleanup_dquot;
 785                                 lock_buffer(new_bh);
 786                                 le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
 787                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
 788                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 789                                 unlock_buffer(new_bh);
 790                                 error = ext3_journal_dirty_metadata(handle,
 791                                                                     new_bh);
 792                                 if (error)
 793                                         goto cleanup_dquot;
 794                         }
 795                         mb_cache_entry_release(ce);
 796                         ce = NULL;
 797                 } else if (bs->bh && s->base == bs->bh->b_data) {
 798                         /* We were modifying this block in-place. */
 799                         ea_bdebug(bs->bh, "keeping this block");
 800                         new_bh = bs->bh;
 801                         get_bh(new_bh);
 802                 } else {
 803                         /* We need to allocate a new block */
 804                         ext3_fsblk_t goal = ext3_group_first_block_no(sb,
 805                                                 EXT3_I(inode)->i_block_group);
 806                         ext3_fsblk_t block;
 807
 808                         /*
 809                          * Protect us agaist concurrent allocations to the
 810                          * same inode from ext3_..._writepage(). Reservation
 811                          * code does not expect racing allocations.
 812                          */
 813                         mutex_lock(&EXT3_I(inode)->truncate_mutex);
 814                         block = ext3_new_block(handle, inode, goal, &error);
 815                         mutex_unlock(&EXT3_I(inode)->truncate_mutex);
 816                         if (error)
 817                                 goto cleanup;
 818                         ea_idebug(inode, "creating block %d", block);
 819
 820                         new_bh = sb_getblk(sb, block);
 821                         if (!new_bh) {
 822 getblk_failed:
 823                                 ext3_free_blocks(handle, inode, block, 1);
 824                                 error = -EIO;
 825                                 goto cleanup;
 826                         }
 827                         lock_buffer(new_bh);
 828                         error = ext3_journal_get_create_access(handle, new_bh);
 829                         if (error) {
 830                                 unlock_buffer(new_bh);
 831                                 goto getblk_failed;
 832                         }
 833                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
 834                         set_buffer_uptodate(new_bh);
 835                         unlock_buffer(new_bh);
 836                         ext3_xattr_cache_insert(new_bh);
 837                         error = ext3_journal_dirty_metadata(handle, new_bh);
 838                         if (error)
 839                                 goto cleanup;
 840                 }
 841         }
 842
 843         /* Update the inode. */
 844         EXT3_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
 845
 846         /* Drop the previous xattr block. */
 847         if (bs->bh && bs->bh != new_bh)
 848                 ext3_xattr_release_block(handle, inode, bs->bh);
 849         error = 0;
 850
 851 cleanup:
 852         if (ce)
 853                 mb_cache_entry_release(ce);
 854         brelse(new_bh);
 855         if (!(bs->bh && s->base == bs->bh->b_data))
 856                 kfree(s->base);
 857
 858         return error;
 859
 860 cleanup_dquot:
 861         dquot_free_block(inode, 1);
 862         goto cleanup;
 863
 864 bad_block:
 865         ext3_error(inode->i_sb, __func__,
 866                    "inode %lu: bad block "E3FSBLK, inode->i_ino,
 867                    EXT3_I(inode)->i_file_acl);
 868         goto cleanup;
 869
 870 #undef header
 871 }
 872
 873 struct ext3_xattr_ibody_find {
 874         struct ext3_xattr_search s;
 875         struct ext3_iloc iloc;
 876 };
 877
 878 static int
 879 ext3_xattr_ibody_find(struct inode *inode, struct ext3_xattr_info *i,
 880                       struct ext3_xattr_ibody_find *is)
 881 {
 882         struct ext3_xattr_ibody_header *header;
 883         struct ext3_inode *raw_inode;
 884         int error;
 885
 886         if (EXT3_I(inode)->i_extra_isize == 0)
 887                 return 0;
 888         raw_inode = ext3_raw_inode(&is->iloc);
 889         header = IHDR(inode, raw_inode);
 890         is->s.base = is->s.first = IFIRST(header);
 891         is->s.here = is->s.first;
 892         is->s.end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 893         if (ext3_test_inode_state(inode, EXT3_STATE_XATTR)) {
 894                 error = ext3_xattr_check_names(IFIRST(header), is->s.end);
 895                 if (error)
 896                         return error;
 897                 /* Find the named attribute. */
 898                 error = ext3_xattr_find_entry(&is->s.here, i->name_index,
 899                                               i->name, is->s.end -
 900                                               (void *)is->s.base, 0);
 901                 if (error && error != -ENODATA)
 902                         return error;
 903                 is->s.not_found = error;
 904         }
 905         return 0;
 906 }
 907
 908 static int
 909 ext3_xattr_ibody_set(handle_t *handle, struct inode *inode,
 910                      struct ext3_xattr_info *i,
 911                      struct ext3_xattr_ibody_find *is)
 912 {
 913         struct ext3_xattr_ibody_header *header;
 914         struct ext3_xattr_search *s = &is->s;
 915         int error;
 916
 917         if (EXT3_I(inode)->i_extra_isize == 0)
 918                 return -ENOSPC;
 919         error = ext3_xattr_set_entry(i, s);
 920         if (error)
 921                 return error;
 922         header = IHDR(inode, ext3_raw_inode(&is->iloc));
 923         if (!IS_LAST_ENTRY(s->first)) {
 924                 header->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
 925                 ext3_set_inode_state(inode, EXT3_STATE_XATTR);
 926         } else {
 927                 header->h_magic = cpu_to_le32(0);
 928                 ext3_clear_inode_state(inode, EXT3_STATE_XATTR);
 929         }
 930         return 0;
 931 }
 932
 933 /*
 934  * ext3_xattr_set_handle()
 935  *
 936  * Create, replace or remove an extended attribute for this inode.  Value
 937  * is NULL to remove an existing extended attribute, and non-NULL to
 938  * either replace an existing extended attribute, or create a new extended
 939  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 940  * specify that an extended attribute must exist and must not exist
 941  * previous to the call, respectively.
 942  *
 943  * Returns 0, or a negative error number on failure.
 944  */
 945 int
 946 ext3_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
 947                       const char *name, const void *value, size_t value_len,
 948                       int flags)
 949 {
 950         struct ext3_xattr_info i = {
 951                 .name_index = name_index,
 952                 .name = name,
 953                 .value = value,
 954                 .value_len = value_len,
 955
 956         };
 957         struct ext3_xattr_ibody_find is = {
 958                 .s = { .not_found = -ENODATA, },
 959         };
 960         struct ext3_xattr_block_find bs = {
 961                 .s = { .not_found = -ENODATA, },
 962         };
 963         int error;
 964
 965         if (!name)
 966                 return -EINVAL;
 967         if (strlen(name) > 255)
 968                 return -ERANGE;
 969         down_write(&EXT3_I(inode)->xattr_sem);
 970         error = ext3_get_inode_loc(inode, &is.iloc);
 971         if (error)
 972                 goto cleanup;
 973
 974         error = ext3_journal_get_write_access(handle, is.iloc.bh);
 975         if (error)
 976                 goto cleanup;
 977
 978         if (ext3_test_inode_state(inode, EXT3_STATE_NEW)) {
 979                 struct ext3_inode *raw_inode = ext3_raw_inode(&is.iloc);
 980                 memset(raw_inode, 0, EXT3_SB(inode->i_sb)->s_inode_size);
 981                 ext3_clear_inode_state(inode, EXT3_STATE_NEW);
 982         }
 983
 984         error = ext3_xattr_ibody_find(inode, &i, &is);
 985         if (error)
 986                 goto cleanup;
 987         if (is.s.not_found)
 988                 error = ext3_xattr_block_find(inode, &i, &bs);
 989         if (error)
 990                 goto cleanup;
 991         if (is.s.not_found && bs.s.not_found) {
 992                 error = -ENODATA;
 993                 if (flags & XATTR_REPLACE)
 994                         goto cleanup;
 995                 error = 0;
 996                 if (!value)
 997                         goto cleanup;
 998         } else {
 999                 error = -EEXIST;
1000                 if (flags & XATTR_CREATE)
1001                         goto cleanup;
1002         }
1003         if (!value) {
1004                 if (!is.s.not_found)
1005                         error = ext3_xattr_ibody_set(handle, inode, &i, &is);
1006                 else if (!bs.s.not_found)
1007                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1008         } else {
1009                 error = ext3_xattr_ibody_set(handle, inode, &i, &is);
1010                 if (!error && !bs.s.not_found) {
1011                         i.value = NULL;
1012                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1013                 } else if (error == -ENOSPC) {
1014                         if (EXT3_I(inode)->i_file_acl && !bs.s.base) {
1015                                 error = ext3_xattr_block_find(inode, &i, &bs);
1016                                 if (error)
1017                                         goto cleanup;
1018                         }
1019                         error = ext3_xattr_block_set(handle, inode, &i, &bs);
1020                         if (error)
1021                                 goto cleanup;
1022                         if (!is.s.not_found) {
1023                                 i.value = NULL;
1024                                 error = ext3_xattr_ibody_set(handle, inode, &i,
1025                                                              &is);
1026                         }
1027                 }
1028         }
1029         if (!error) {
1030                 ext3_xattr_update_super_block(handle, inode->i_sb);
1031                 inode->i_ctime = CURRENT_TIME_SEC;
1032                 error = ext3_mark_iloc_dirty(handle, inode, &is.iloc);
1033                 /*
1034                  * The bh is consumed by ext3_mark_iloc_dirty, even with
1035                  * error != 0.
1036                  */
1037                 is.iloc.bh = NULL;
1038                 if (IS_SYNC(inode))
1039                         handle->h_sync = 1;
1040         }
1041
1042 cleanup:
1043         brelse(is.iloc.bh);
1044         brelse(bs.bh);
1045         up_write(&EXT3_I(inode)->xattr_sem);
1046         return error;
1047 }
1048
1049 /*
1050  * ext3_xattr_set()
1051  *
1052  * Like ext3_xattr_set_handle, but start from an inode. This extended
1053  * attribute modification is a filesystem transaction by itself.
1054  *
1055  * Returns 0, or a negative error number on failure.
1056  */
1057 int
1058 ext3_xattr_set(struct inode *inode, int name_index, const char *name,
1059                const void *value, size_t value_len, int flags)
1060 {
1061         handle_t *handle;
1062         int error, retries = 0;
1063
1064 retry:
1065         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
1066         if (IS_ERR(handle)) {
1067                 error = PTR_ERR(handle);
1068         } else {
1069                 int error2;
1070
1071                 error = ext3_xattr_set_handle(handle, inode, name_index, name,
1072                                               value, value_len, flags);
1073                 error2 = ext3_journal_stop(handle);
1074                 if (error == -ENOSPC &&
1075                     ext3_should_retry_alloc(inode->i_sb, &retries))
1076                         goto retry;
1077                 if (error == 0)
1078                         error = error2;
1079         }
1080
1081         return error;
1082 }
1083
1084 /*
1085  * ext3_xattr_delete_inode()
1086  *
1087  * Free extended attribute resources associated with this inode. This
1088  * is called immediately before an inode is freed. We have exclusive
1089  * access to the inode.
1090  */
1091 void
1092 ext3_xattr_delete_inode(handle_t *handle, struct inode *inode)
1093 {
1094         struct buffer_head *bh = NULL;
1095
1096         if (!EXT3_I(inode)->i_file_acl)
1097                 goto cleanup;
1098         bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
1099         if (!bh) {
1100                 ext3_error(inode->i_sb, __func__,
1101                         "inode %lu: block "E3FSBLK" read error", inode->i_ino,
1102                         EXT3_I(inode)->i_file_acl);
1103                 goto cleanup;
1104         }
1105         if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
1106             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1107                 ext3_error(inode->i_sb, __func__,
1108                         "inode %lu: bad block "E3FSBLK, inode->i_ino,
1109                         EXT3_I(inode)->i_file_acl);
1110                 goto cleanup;
1111         }
1112         ext3_xattr_release_block(handle, inode, bh);
1113         EXT3_I(inode)->i_file_acl = 0;
1114
1115 cleanup:
1116         brelse(bh);
1117 }
1118
1119 /*
1120  * ext3_xattr_put_super()
1121  *
1122  * This is called when a file system is unmounted.
1123  */
1124 void
1125 ext3_xattr_put_super(struct super_block *sb)
1126 {
1127         mb_cache_shrink(sb->s_bdev);
1128 }
1129
1130 /*
1131  * ext3_xattr_cache_insert()
1132  *
1133  * Create a new entry in the extended attribute cache, and insert
1134  * it unless such an entry is already in the cache.
1135  *
1136  * Returns 0, or a negative error number on failure.
1137  */
1138 static void
1139 ext3_xattr_cache_insert(struct buffer_head *bh)
1140 {
1141         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1142         struct mb_cache_entry *ce;
1143         int error;
1144
1145         ce = mb_cache_entry_alloc(ext3_xattr_cache, GFP_NOFS);
1146         if (!ce) {
1147                 ea_bdebug(bh, "out of memory");
1148                 return;
1149         }
1150         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
1151         if (error) {
1152                 mb_cache_entry_free(ce);
1153                 if (error == -EBUSY) {
1154                         ea_bdebug(bh, "already in cache");
1155                         error = 0;
1156                 }
1157         } else {
1158                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1159                 mb_cache_entry_release(ce);
1160         }
1161 }
1162
1163 /*
1164  * ext3_xattr_cmp()
1165  *
1166  * Compare two extended attribute blocks for equality.
1167  *
1168  * Returns 0 if the blocks are equal, 1 if they differ, and
1169  * a negative error number on errors.
1170  */
1171 static int
1172 ext3_xattr_cmp(struct ext3_xattr_header *header1,
1173                struct ext3_xattr_header *header2)
1174 {
1175         struct ext3_xattr_entry *entry1, *entry2;
1176
1177         entry1 = ENTRY(header1+1);
1178         entry2 = ENTRY(header2+1);
1179         while (!IS_LAST_ENTRY(entry1)) {
1180                 if (IS_LAST_ENTRY(entry2))
1181                         return 1;
1182                 if (entry1->e_hash != entry2->e_hash ||
1183                     entry1->e_name_index != entry2->e_name_index ||
1184                     entry1->e_name_len != entry2->e_name_len ||
1185                     entry1->e_value_size != entry2->e_value_size ||
1186                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1187                         return 1;
1188                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1189                         return -EIO;
1190                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1191                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1192                            le32_to_cpu(entry1->e_value_size)))
1193                         return 1;
1194
1195                 entry1 = EXT3_XATTR_NEXT(entry1);
1196                 entry2 = EXT3_XATTR_NEXT(entry2);
1197         }
1198         if (!IS_LAST_ENTRY(entry2))
1199                 return 1;
1200         return 0;
1201 }
1202
1203 /*
1204  * ext3_xattr_cache_find()
1205  *
1206  * Find an identical extended attribute block.
1207  *
1208  * Returns a pointer to the block found, or NULL if such a block was
1209  * not found or an error occurred.
1210  */
1211 static struct buffer_head *
1212 ext3_xattr_cache_find(struct inode *inode, struct ext3_xattr_header *header,
1213                       struct mb_cache_entry **pce)
1214 {
1215         __u32 hash = le32_to_cpu(header->h_hash);
1216         struct mb_cache_entry *ce;
1217
1218         if (!header->h_hash)
1219                 return NULL;  /* never share */
1220         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1221 again:
1222         ce = mb_cache_entry_find_first(ext3_xattr_cache, inode->i_sb->s_bdev,
1223                                        hash);
1224         while (ce) {
1225                 struct buffer_head *bh;
1226
1227                 if (IS_ERR(ce)) {
1228                         if (PTR_ERR(ce) == -EAGAIN)
1229                                 goto again;
1230                         break;
1231                 }
1232                 bh = sb_bread(inode->i_sb, ce->e_block);
1233                 if (!bh) {
1234                         ext3_error(inode->i_sb, __func__,
1235                                 "inode %lu: block %lu read error",
1236                                 inode->i_ino, (unsigned long) ce->e_block);
1237                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1238                                 EXT3_XATTR_REFCOUNT_MAX) {
1239                         ea_idebug(inode, "block %lu refcount %d>=%d",
1240                                   (unsigned long) ce->e_block,
1241                                   le32_to_cpu(BHDR(bh)->h_refcount),
1242                                           EXT3_XATTR_REFCOUNT_MAX);
1243                 } else if (ext3_xattr_cmp(header, BHDR(bh)) == 0) {
1244                         *pce = ce;
1245                         return bh;
1246                 }
1247                 brelse(bh);
1248                 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
1249         }
1250         return NULL;
1251 }
1252
1253 #define NAME_HASH_SHIFT 5
1254 #define VALUE_HASH_SHIFT 16
1255
1256 /*
1257  * ext3_xattr_hash_entry()
1258  *
1259  * Compute the hash of an extended attribute.
1260  */
1261 static inline void ext3_xattr_hash_entry(struct ext3_xattr_header *header,
1262                                          struct ext3_xattr_entry *entry)
1263 {
1264         __u32 hash = 0;
1265         char *name = entry->e_name;
1266         int n;
1267
1268         for (n=0; n < entry->e_name_len; n++) {
1269                 hash = (hash << NAME_HASH_SHIFT) ^
1270                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1271                        *name++;
1272         }
1273
1274         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1275                 __le32 *value = (__le32 *)((char *)header +
1276                         le16_to_cpu(entry->e_value_offs));
1277                 for (n = (le32_to_cpu(entry->e_value_size) +
1278                      EXT3_XATTR_ROUND) >> EXT3_XATTR_PAD_BITS; n; n--) {
1279                         hash = (hash << VALUE_HASH_SHIFT) ^
1280                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1281                                le32_to_cpu(*value++);
1282                 }
1283         }
1284         entry->e_hash = cpu_to_le32(hash);
1285 }
1286
1287 #undef NAME_HASH_SHIFT
1288 #undef VALUE_HASH_SHIFT
1289
1290 #define BLOCK_HASH_SHIFT 16
1291
1292 /*
1293  * ext3_xattr_rehash()
1294  *
1295  * Re-compute the extended attribute hash value after an entry has changed.
1296  */
1297 static void ext3_xattr_rehash(struct ext3_xattr_header *header,
1298                               struct ext3_xattr_entry *entry)
1299 {
1300         struct ext3_xattr_entry *here;
1301         __u32 hash = 0;
1302
1303         ext3_xattr_hash_entry(header, entry);
1304         here = ENTRY(header+1);
1305         while (!IS_LAST_ENTRY(here)) {
1306                 if (!here->e_hash) {
1307                         /* Block is not shared if an entry's hash value == 0 */
1308                         hash = 0;
1309                         break;
1310                 }
1311                 hash = (hash << BLOCK_HASH_SHIFT) ^
1312                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1313                        le32_to_cpu(here->e_hash);
1314                 here = EXT3_XATTR_NEXT(here);
1315         }
1316         header->h_hash = cpu_to_le32(hash);
1317 }
1318
1319 #undef BLOCK_HASH_SHIFT
1320
1321 int __init
1322 init_ext3_xattr(void)
1323 {
1324         ext3_xattr_cache = mb_cache_create("ext3_xattr", 6);
1325         if (!ext3_xattr_cache)
1326                 return -ENOMEM;
1327         return 0;
1328 }
1329
1330 void
1331 exit_ext3_xattr(void)
1332 {
1333         if (ext3_xattr_cache)
1334                 mb_cache_destroy(ext3_xattr_cache);
1335         ext3_xattr_cache = NULL;
1336 }