linux/fs/ext3/xattr.c
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   1/*
   2 * linux/fs/ext3/xattr.c
   3 *
   4 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   5 *
   6 * Fix by Harrison Xing <harrison@mountainviewdata.com>.
   7 * Ext3 code with a lot of help from Eric Jarman <ejarman@acm.org>.
   8 * Extended attributes for symlinks and special files added per
   9 *  suggestion of Luka Renko <luka.renko@hermes.si>.
  10 * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
  11 *  Red Hat Inc.
  12 * ea-in-inode support by Alex Tomas <alex@clusterfs.com> aka bzzz
  13 *  and Andreas Gruenbacher <agruen@suse.de>.
  14 */
  15
  16/*
  17 * Extended attributes are stored directly in inodes (on file systems with
  18 * inodes bigger than 128 bytes) and on additional disk blocks. The i_file_acl
  19 * field contains the block number if an inode uses an additional block. All
  20 * attributes must fit in the inode and one additional block. Blocks that
  21 * contain the identical set of attributes may be shared among several inodes.
  22 * Identical blocks are detected by keeping a cache of blocks that have
  23 * recently been accessed.
  24 *
  25 * The attributes in inodes and on blocks have a different header; the entries
  26 * are stored in the same format:
  27 *
  28 *   +------------------+
  29 *   | header           |
  30 *   | entry 1          | |
  31 *   | entry 2          | | growing downwards
  32 *   | entry 3          | v
  33 *   | four null bytes  |
  34 *   | . . .            |
  35 *   | value 1          | ^
  36 *   | value 3          | | growing upwards
  37 *   | value 2          | |
  38 *   +------------------+
  39 *
  40 * The header is followed by multiple entry descriptors. In disk blocks, the
  41 * entry descriptors are kept sorted. In inodes, they are unsorted. The
  42 * attribute values are aligned to the end of the block in no specific order.
  43 *
  44 * Locking strategy
  45 * ----------------
  46 * EXT3_I(inode)->i_file_acl is protected by EXT3_I(inode)->xattr_sem.
  47 * EA blocks are only changed if they are exclusive to an inode, so
  48 * holding xattr_sem also means that nothing but the EA block's reference
  49 * count can change. Multiple writers to the same block are synchronized
  50 * by the buffer lock.
  51 */
  52
  53#include "ext3.h"
  54#include <linux/mbcache.h>
  55#include <linux/quotaops.h>
  56#include "xattr.h"
  57#include "acl.h"
  58
  59#define BHDR(bh) ((struct ext3_xattr_header *)((bh)->b_data))
  60#define ENTRY(ptr) ((struct ext3_xattr_entry *)(ptr))
  61#define BFIRST(bh) ENTRY(BHDR(bh)+1)
  62#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
  63
  64#define IHDR(inode, raw_inode) \
  65        ((struct ext3_xattr_ibody_header *) \
  66                ((void *)raw_inode + \
  67                 EXT3_GOOD_OLD_INODE_SIZE + \
  68                 EXT3_I(inode)->i_extra_isize))
  69#define IFIRST(hdr) ((struct ext3_xattr_entry *)((hdr)+1))
  70
  71#ifdef EXT3_XATTR_DEBUG
  72# define ea_idebug(inode, f...) do { \
  73                printk(KERN_DEBUG "inode %s:%lu: ", \
  74                        inode->i_sb->s_id, inode->i_ino); \
  75                printk(f); \
  76                printk("\n"); \
  77        } while (0)
  78# define ea_bdebug(bh, f...) do { \
  79                char b[BDEVNAME_SIZE]; \
  80                printk(KERN_DEBUG "block %s:%lu: ", \
  81                        bdevname(bh->b_bdev, b), \
  82                        (unsigned long) bh->b_blocknr); \
  83                printk(f); \
  84                printk("\n"); \
  85        } while (0)
  86#else
  87# define ea_idebug(f...)
  88# define ea_bdebug(f...)
  89#endif
  90
  91static void ext3_xattr_cache_insert(struct buffer_head *);
  92static struct buffer_head *ext3_xattr_cache_find(struct inode *,
  93                                                 struct ext3_xattr_header *,
  94                                                 struct mb_cache_entry **);
  95static void ext3_xattr_rehash(struct ext3_xattr_header *,
  96                              struct ext3_xattr_entry *);
  97static int ext3_xattr_list(struct dentry *dentry, char *buffer,
  98                           size_t buffer_size);
  99
 100static struct mb_cache *ext3_xattr_cache;
 101
 102static const struct xattr_handler *ext3_xattr_handler_map[] = {
 103        [EXT3_XATTR_INDEX_USER]              = &ext3_xattr_user_handler,
 104#ifdef CONFIG_EXT3_FS_POSIX_ACL
 105        [EXT3_XATTR_INDEX_POSIX_ACL_ACCESS]  = &ext3_xattr_acl_access_handler,
 106        [EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext3_xattr_acl_default_handler,
 107#endif
 108        [EXT3_XATTR_INDEX_TRUSTED]           = &ext3_xattr_trusted_handler,
 109#ifdef CONFIG_EXT3_FS_SECURITY
 110        [EXT3_XATTR_INDEX_SECURITY]          = &ext3_xattr_security_handler,
 111#endif
 112};
 113
 114const struct xattr_handler *ext3_xattr_handlers[] = {
 115        &ext3_xattr_user_handler,
 116        &ext3_xattr_trusted_handler,
 117#ifdef CONFIG_EXT3_FS_POSIX_ACL
 118        &ext3_xattr_acl_access_handler,
 119        &ext3_xattr_acl_default_handler,
 120#endif
 121#ifdef CONFIG_EXT3_FS_SECURITY
 122        &ext3_xattr_security_handler,
 123#endif
 124        NULL
 125};
 126
 127static inline const struct xattr_handler *
 128ext3_xattr_handler(int name_index)
 129{
 130        const struct xattr_handler *handler = NULL;
 131
 132        if (name_index > 0 && name_index < ARRAY_SIZE(ext3_xattr_handler_map))
 133                handler = ext3_xattr_handler_map[name_index];
 134        return handler;
 135}
 136
 137/*
 138 * Inode operation listxattr()
 139 *
 140 * dentry->d_inode->i_mutex: don't care
 141 */
 142ssize_t
 143ext3_listxattr(struct dentry *dentry, char *buffer, size_t size)
 144{
 145        return ext3_xattr_list(dentry, buffer, size);
 146}
 147
 148static int
 149ext3_xattr_check_names(struct ext3_xattr_entry *entry, void *end)
 150{
 151        while (!IS_LAST_ENTRY(entry)) {
 152                struct ext3_xattr_entry *next = EXT3_XATTR_NEXT(entry);
 153                if ((void *)next >= end)
 154                        return -EIO;
 155                entry = next;
 156        }
 157        return 0;
 158}
 159
 160static inline int
 161ext3_xattr_check_block(struct buffer_head *bh)
 162{
 163        int error;
 164
 165        if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
 166            BHDR(bh)->h_blocks != cpu_to_le32(1))
 167                return -EIO;
 168        error = ext3_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
 169        return error;
 170}
 171
 172static inline int
 173ext3_xattr_check_entry(struct ext3_xattr_entry *entry, size_t size)
 174{
 175        size_t value_size = le32_to_cpu(entry->e_value_size);
 176
 177        if (entry->e_value_block != 0 || value_size > size ||
 178            le16_to_cpu(entry->e_value_offs) + value_size > size)
 179                return -EIO;
 180        return 0;
 181}
 182
 183static int
 184ext3_xattr_find_entry(struct ext3_xattr_entry **pentry, int name_index,
 185                      const char *name, size_t size, int sorted)
 186{
 187        struct ext3_xattr_entry *entry;
 188        size_t name_len;
 189        int cmp = 1;
 190
 191        if (name == NULL)
 192                return -EINVAL;
 193        name_len = strlen(name);
 194        entry = *pentry;
 195        for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
 196                cmp = name_index - entry->e_name_index;
 197                if (!cmp)
 198                        cmp = name_len - entry->e_name_len;
 199                if (!cmp)
 200                        cmp = memcmp(name, entry->e_name, name_len);
 201                if (cmp <= 0 && (sorted || cmp == 0))
 202                        break;
 203        }
 204        *pentry = entry;
 205        if (!cmp && ext3_xattr_check_entry(entry, size))
 206                        return -EIO;
 207        return cmp ? -ENODATA : 0;
 208}
 209
 210static int
 211ext3_xattr_block_get(struct inode *inode, int name_index, const char *name,
 212                     void *buffer, size_t buffer_size)
 213{
 214        struct buffer_head *bh = NULL;
 215        struct ext3_xattr_entry *entry;
 216        size_t size;
 217        int error;
 218
 219        ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 220                  name_index, name, buffer, (long)buffer_size);
 221
 222        error = -ENODATA;
 223        if (!EXT3_I(inode)->i_file_acl)
 224                goto cleanup;
 225        ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
 226        bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
 227        if (!bh)
 228                goto cleanup;
 229        ea_bdebug(bh, "b_count=%d, refcount=%d",
 230                atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 231        if (ext3_xattr_check_block(bh)) {
 232bad_block:      ext3_error(inode->i_sb, __func__,
 233                           "inode %lu: bad block "E3FSBLK, inode->i_ino,
 234                           EXT3_I(inode)->i_file_acl);
 235                error = -EIO;
 236                goto cleanup;
 237        }
 238        ext3_xattr_cache_insert(bh);
 239        entry = BFIRST(bh);
 240        error = ext3_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
 241        if (error == -EIO)
 242                goto bad_block;
 243        if (error)
 244                goto cleanup;
 245        size = le32_to_cpu(entry->e_value_size);
 246        if (buffer) {
 247                error = -ERANGE;
 248                if (size > buffer_size)
 249                        goto cleanup;
 250                memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
 251                       size);
 252        }
 253        error = size;
 254
 255cleanup:
 256        brelse(bh);
 257        return error;
 258}
 259
 260static int
 261ext3_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 262                     void *buffer, size_t buffer_size)
 263{
 264        struct ext3_xattr_ibody_header *header;
 265        struct ext3_xattr_entry *entry;
 266        struct ext3_inode *raw_inode;
 267        struct ext3_iloc iloc;
 268        size_t size;
 269        void *end;
 270        int error;
 271
 272        if (!ext3_test_inode_state(inode, EXT3_STATE_XATTR))
 273                return -ENODATA;
 274        error = ext3_get_inode_loc(inode, &iloc);
 275        if (error)
 276                return error;
 277        raw_inode = ext3_raw_inode(&iloc);
 278        header = IHDR(inode, raw_inode);
 279        entry = IFIRST(header);
 280        end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 281        error = ext3_xattr_check_names(entry, end);
 282        if (error)
 283                goto cleanup;
 284        error = ext3_xattr_find_entry(&entry, name_index, name,
 285                                      end - (void *)entry, 0);
 286        if (error)
 287                goto cleanup;
 288        size = le32_to_cpu(entry->e_value_size);
 289        if (buffer) {
 290                error = -ERANGE;
 291                if (size > buffer_size)
 292                        goto cleanup;
 293                memcpy(buffer, (void *)IFIRST(header) +
 294                       le16_to_cpu(entry->e_value_offs), size);
 295        }
 296        error = size;
 297
 298cleanup:
 299        brelse(iloc.bh);
 300        return error;
 301}
 302
 303/*
 304 * ext3_xattr_get()
 305 *
 306 * Copy an extended attribute into the buffer
 307 * provided, or compute the buffer size required.
 308 * Buffer is NULL to compute the size of the buffer required.
 309 *
 310 * Returns a negative error number on failure, or the number of bytes
 311 * used / required on success.
 312 */
 313int
 314ext3_xattr_get(struct inode *inode, int name_index, const char *name,
 315               void *buffer, size_t buffer_size)
 316{
 317        int error;
 318
 319        down_read(&EXT3_I(inode)->xattr_sem);
 320        error = ext3_xattr_ibody_get(inode, name_index, name, buffer,
 321                                     buffer_size);
 322        if (error == -ENODATA)
 323                error = ext3_xattr_block_get(inode, name_index, name, buffer,
 324                                             buffer_size);
 325        up_read(&EXT3_I(inode)->xattr_sem);
 326        return error;
 327}
 328
 329static int
 330ext3_xattr_list_entries(struct dentry *dentry, struct ext3_xattr_entry *entry,
 331                        char *buffer, size_t buffer_size)
 332{
 333        size_t rest = buffer_size;
 334
 335        for (; !IS_LAST_ENTRY(entry); entry = EXT3_XATTR_NEXT(entry)) {
 336                const struct xattr_handler *handler =
 337                        ext3_xattr_handler(entry->e_name_index);
 338
 339                if (handler) {
 340                        size_t size = handler->list(dentry, buffer, rest,
 341                                                    entry->e_name,
 342                                                    entry->e_name_len,
 343                                                    handler->flags);
 344                        if (buffer) {
 345                                if (size > rest)
 346                                        return -ERANGE;
 347                                buffer += size;
 348                        }
 349                        rest -= size;
 350                }
 351        }
 352        return buffer_size - rest;
 353}
 354
 355static int
 356ext3_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 357{
 358        struct inode *inode = dentry->d_inode;
 359        struct buffer_head *bh = NULL;
 360        int error;
 361
 362        ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 363                  buffer, (long)buffer_size);
 364
 365        error = 0;
 366        if (!EXT3_I(inode)->i_file_acl)
 367                goto cleanup;
 368        ea_idebug(inode, "reading block %u", EXT3_I(inode)->i_file_acl);
 369        bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
 370        error = -EIO;
 371        if (!bh)
 372                goto cleanup;
 373        ea_bdebug(bh, "b_count=%d, refcount=%d",
 374                atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 375        if (ext3_xattr_check_block(bh)) {
 376                ext3_error(inode->i_sb, __func__,
 377                           "inode %lu: bad block "E3FSBLK, inode->i_ino,
 378                           EXT3_I(inode)->i_file_acl);
 379                error = -EIO;
 380                goto cleanup;
 381        }
 382        ext3_xattr_cache_insert(bh);
 383        error = ext3_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
 384
 385cleanup:
 386        brelse(bh);
 387
 388        return error;
 389}
 390
 391static int
 392ext3_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 393{
 394        struct inode *inode = dentry->d_inode;
 395        struct ext3_xattr_ibody_header *header;
 396        struct ext3_inode *raw_inode;
 397        struct ext3_iloc iloc;
 398        void *end;
 399        int error;
 400
 401        if (!ext3_test_inode_state(inode, EXT3_STATE_XATTR))
 402                return 0;
 403        error = ext3_get_inode_loc(inode, &iloc);
 404        if (error)
 405                return error;
 406        raw_inode = ext3_raw_inode(&iloc);
 407        header = IHDR(inode, raw_inode);
 408        end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 409        error = ext3_xattr_check_names(IFIRST(header), end);
 410        if (error)
 411                goto cleanup;
 412        error = ext3_xattr_list_entries(dentry, IFIRST(header),
 413                                        buffer, buffer_size);
 414
 415cleanup:
 416        brelse(iloc.bh);
 417        return error;
 418}
 419
 420/*
 421 * ext3_xattr_list()
 422 *
 423 * Copy a list of attribute names into the buffer
 424 * provided, or compute the buffer size required.
 425 * Buffer is NULL to compute the size of the buffer required.
 426 *
 427 * Returns a negative error number on failure, or the number of bytes
 428 * used / required on success.
 429 */
 430static int
 431ext3_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 432{
 433        int i_error, b_error;
 434
 435        down_read(&EXT3_I(dentry->d_inode)->xattr_sem);
 436        i_error = ext3_xattr_ibody_list(dentry, buffer, buffer_size);
 437        if (i_error < 0) {
 438                b_error = 0;
 439        } else {
 440                if (buffer) {
 441                        buffer += i_error;
 442                        buffer_size -= i_error;
 443                }
 444                b_error = ext3_xattr_block_list(dentry, buffer, buffer_size);
 445                if (b_error < 0)
 446                        i_error = 0;
 447        }
 448        up_read(&EXT3_I(dentry->d_inode)->xattr_sem);
 449        return i_error + b_error;
 450}
 451
 452/*
 453 * If the EXT3_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 454 * not set, set it.
 455 */
 456static void ext3_xattr_update_super_block(handle_t *handle,
 457                                          struct super_block *sb)
 458{
 459        if (EXT3_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR))
 460                return;
 461
 462        if (ext3_journal_get_write_access(handle, EXT3_SB(sb)->s_sbh) == 0) {
 463                EXT3_SET_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_EXT_ATTR);
 464                ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh);
 465        }
 466}
 467
 468/*
 469 * Release the xattr block BH: If the reference count is > 1, decrement
 470 * it; otherwise free the block.
 471 */
 472static void
 473ext3_xattr_release_block(handle_t *handle, struct inode *inode,
 474                         struct buffer_head *bh)
 475{
 476        struct mb_cache_entry *ce = NULL;
 477        int error = 0;
 478
 479        ce = mb_cache_entry_get(ext3_xattr_cache, bh->b_bdev, bh->b_blocknr);
 480        error = ext3_journal_get_write_access(handle, bh);
 481        if (error)
 482                 goto out;
 483
 484        lock_buffer(bh);
 485
 486        if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
 487                ea_bdebug(bh, "refcount now=0; freeing");
 488                if (ce)
 489                        mb_cache_entry_free(ce);
 490                ext3_free_blocks(handle, inode, bh->b_blocknr, 1);
 491                get_bh(bh);
 492                ext3_forget(handle, 1, inode, bh, bh->b_blocknr);
 493        } else {
 494                le32_add_cpu(&BHDR(bh)->h_refcount, -1);
 495                error = ext3_journal_dirty_metadata(handle, bh);
 496                if (IS_SYNC(inode))
 497                        handle->h_sync = 1;
 498                dquot_free_block(inode, 1);
 499                ea_bdebug(bh, "refcount now=%d; releasing",
 500                          le32_to_cpu(BHDR(bh)->h_refcount));
 501                if (ce)
 502                        mb_cache_entry_release(ce);
 503        }
 504        unlock_buffer(bh);
 505out:
 506        ext3_std_error(inode->i_sb, error);
 507        return;
 508}
 509
 510struct ext3_xattr_info {
 511        int name_index;
 512        const char *name;
 513        const void *value;
 514        size_t value_len;
 515};
 516
 517struct 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
 525static int
 526ext3_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
 626struct ext3_xattr_block_find {
 627        struct ext3_xattr_search s;
 628        struct buffer_head *bh;
 629};
 630
 631static int
 632ext3_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, __func__,
 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
 670cleanup:
 671        return error;
 672}
 673
 674static int
 675ext3_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 = 0;
 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                error = ext3_journal_get_write_access(handle, bs->bh);
 693                if (error)
 694                        goto cleanup;
 695                lock_buffer(bs->bh);
 696
 697                if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 698                        if (ce) {
 699                                mb_cache_entry_free(ce);
 700                                ce = NULL;
 701                        }
 702                        ea_bdebug(bs->bh, "modifying in-place");
 703                        error = ext3_xattr_set_entry(i, s);
 704                        if (!error) {
 705                                if (!IS_LAST_ENTRY(s->first))
 706                                        ext3_xattr_rehash(header(s->base),
 707                                                          s->here);
 708                                ext3_xattr_cache_insert(bs->bh);
 709                        }
 710                        unlock_buffer(bs->bh);
 711                        if (error == -EIO)
 712                                goto bad_block;
 713                        if (!error)
 714                                error = ext3_journal_dirty_metadata(handle,
 715                                                                    bs->bh);
 716                        if (error)
 717                                goto cleanup;
 718                        goto inserted;
 719                } else {
 720                        int offset = (char *)s->here - bs->bh->b_data;
 721
 722                        unlock_buffer(bs->bh);
 723                        journal_release_buffer(handle, bs->bh);
 724
 725                        if (ce) {
 726                                mb_cache_entry_release(ce);
 727                                ce = NULL;
 728                        }
 729                        ea_bdebug(bs->bh, "cloning");
 730                        s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
 731                        error = -ENOMEM;
 732                        if (s->base == NULL)
 733                                goto cleanup;
 734                        memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 735                        s->first = ENTRY(header(s->base)+1);
 736                        header(s->base)->h_refcount = cpu_to_le32(1);
 737                        s->here = ENTRY(s->base + offset);
 738                        s->end = s->base + bs->bh->b_size;
 739                }
 740        } else {
 741                /* Allocate a buffer where we construct the new block. */
 742                s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
 743                /* assert(header == s->base) */
 744                error = -ENOMEM;
 745                if (s->base == NULL)
 746                        goto cleanup;
 747                header(s->base)->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
 748                header(s->base)->h_blocks = cpu_to_le32(1);
 749                header(s->base)->h_refcount = cpu_to_le32(1);
 750                s->first = ENTRY(header(s->base)+1);
 751                s->here = ENTRY(header(s->base)+1);
 752                s->end = s->base + sb->s_blocksize;
 753        }
 754
 755        error = ext3_xattr_set_entry(i, s);
 756        if (error == -EIO)
 757                goto bad_block;
 758        if (error)
 759                goto cleanup;
 760        if (!IS_LAST_ENTRY(s->first))
 761                ext3_xattr_rehash(header(s->base), s->here);
 762
 763inserted:
 764        if (!IS_LAST_ENTRY(s->first)) {
 765                new_bh = ext3_xattr_cache_find(inode, header(s->base), &ce);
 766                if (new_bh) {
 767                        /* We found an identical block in the cache. */
 768                        if (new_bh == bs->bh)
 769                                ea_bdebug(new_bh, "keeping");
 770                        else {
 771                                /* The old block is released after updating
 772                                   the inode. */
 773                                error = dquot_alloc_block(inode, 1);
 774                                if (error)
 775                                        goto cleanup;
 776                                error = ext3_journal_get_write_access(handle,
 777                                                                      new_bh);
 778                                if (error)
 779                                        goto cleanup_dquot;
 780                                lock_buffer(new_bh);
 781                                le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
 782                                ea_bdebug(new_bh, "reusing; refcount now=%d",
 783                                        le32_to_cpu(BHDR(new_bh)->h_refcount));
 784                                unlock_buffer(new_bh);
 785                                error = ext3_journal_dirty_metadata(handle,
 786                                                                    new_bh);
 787                                if (error)
 788                                        goto cleanup_dquot;
 789                        }
 790                        mb_cache_entry_release(ce);
 791                        ce = NULL;
 792                } else if (bs->bh && s->base == bs->bh->b_data) {
 793                        /* We were modifying this block in-place. */
 794                        ea_bdebug(bs->bh, "keeping this block");
 795                        new_bh = bs->bh;
 796                        get_bh(new_bh);
 797                } else {
 798                        /* We need to allocate a new block */
 799                        ext3_fsblk_t goal = ext3_group_first_block_no(sb,
 800                                                EXT3_I(inode)->i_block_group);
 801                        ext3_fsblk_t block;
 802
 803                        /*
 804                         * Protect us agaist concurrent allocations to the
 805                         * same inode from ext3_..._writepage(). Reservation
 806                         * code does not expect racing allocations.
 807                         */
 808                        mutex_lock(&EXT3_I(inode)->truncate_mutex);
 809                        block = ext3_new_block(handle, inode, goal, &error);
 810                        mutex_unlock(&EXT3_I(inode)->truncate_mutex);
 811                        if (error)
 812                                goto cleanup;
 813                        ea_idebug(inode, "creating block %d", block);
 814
 815                        new_bh = sb_getblk(sb, block);
 816                        if (unlikely(!new_bh)) {
 817getblk_failed:
 818                                ext3_free_blocks(handle, inode, block, 1);
 819                                error = -ENOMEM;
 820                                goto cleanup;
 821                        }
 822                        lock_buffer(new_bh);
 823                        error = ext3_journal_get_create_access(handle, new_bh);
 824                        if (error) {
 825                                unlock_buffer(new_bh);
 826                                goto getblk_failed;
 827                        }
 828                        memcpy(new_bh->b_data, s->base, new_bh->b_size);
 829                        set_buffer_uptodate(new_bh);
 830                        unlock_buffer(new_bh);
 831                        ext3_xattr_cache_insert(new_bh);
 832                        error = ext3_journal_dirty_metadata(handle, new_bh);
 833                        if (error)
 834                                goto cleanup;
 835                }
 836        }
 837
 838        /* Update the inode. */
 839        EXT3_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
 840
 841        /* Drop the previous xattr block. */
 842        if (bs->bh && bs->bh != new_bh)
 843                ext3_xattr_release_block(handle, inode, bs->bh);
 844        error = 0;
 845
 846cleanup:
 847        if (ce)
 848                mb_cache_entry_release(ce);
 849        brelse(new_bh);
 850        if (!(bs->bh && s->base == bs->bh->b_data))
 851                kfree(s->base);
 852
 853        return error;
 854
 855cleanup_dquot:
 856        dquot_free_block(inode, 1);
 857        goto cleanup;
 858
 859bad_block:
 860        ext3_error(inode->i_sb, __func__,
 861                   "inode %lu: bad block "E3FSBLK, inode->i_ino,
 862                   EXT3_I(inode)->i_file_acl);
 863        goto cleanup;
 864
 865#undef header
 866}
 867
 868struct ext3_xattr_ibody_find {
 869        struct ext3_xattr_search s;
 870        struct ext3_iloc iloc;
 871};
 872
 873static int
 874ext3_xattr_ibody_find(struct inode *inode, struct ext3_xattr_info *i,
 875                      struct ext3_xattr_ibody_find *is)
 876{
 877        struct ext3_xattr_ibody_header *header;
 878        struct ext3_inode *raw_inode;
 879        int error;
 880
 881        if (EXT3_I(inode)->i_extra_isize == 0)
 882                return 0;
 883        raw_inode = ext3_raw_inode(&is->iloc);
 884        header = IHDR(inode, raw_inode);
 885        is->s.base = is->s.first = IFIRST(header);
 886        is->s.here = is->s.first;
 887        is->s.end = (void *)raw_inode + EXT3_SB(inode->i_sb)->s_inode_size;
 888        if (ext3_test_inode_state(inode, EXT3_STATE_XATTR)) {
 889                error = ext3_xattr_check_names(IFIRST(header), is->s.end);
 890                if (error)
 891                        return error;
 892                /* Find the named attribute. */
 893                error = ext3_xattr_find_entry(&is->s.here, i->name_index,
 894                                              i->name, is->s.end -
 895                                              (void *)is->s.base, 0);
 896                if (error && error != -ENODATA)
 897                        return error;
 898                is->s.not_found = error;
 899        }
 900        return 0;
 901}
 902
 903static int
 904ext3_xattr_ibody_set(handle_t *handle, struct inode *inode,
 905                     struct ext3_xattr_info *i,
 906                     struct ext3_xattr_ibody_find *is)
 907{
 908        struct ext3_xattr_ibody_header *header;
 909        struct ext3_xattr_search *s = &is->s;
 910        int error;
 911
 912        if (EXT3_I(inode)->i_extra_isize == 0)
 913                return -ENOSPC;
 914        error = ext3_xattr_set_entry(i, s);
 915        if (error)
 916                return error;
 917        header = IHDR(inode, ext3_raw_inode(&is->iloc));
 918        if (!IS_LAST_ENTRY(s->first)) {
 919                header->h_magic = cpu_to_le32(EXT3_XATTR_MAGIC);
 920                ext3_set_inode_state(inode, EXT3_STATE_XATTR);
 921        } else {
 922                header->h_magic = cpu_to_le32(0);
 923                ext3_clear_inode_state(inode, EXT3_STATE_XATTR);
 924        }
 925        return 0;
 926}
 927
 928/*
 929 * ext3_xattr_set_handle()
 930 *
 931 * Create, replace or remove an extended attribute for this inode.  Value
 932 * is NULL to remove an existing extended attribute, and non-NULL to
 933 * either replace an existing extended attribute, or create a new extended
 934 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 935 * specify that an extended attribute must exist and must not exist
 936 * previous to the call, respectively.
 937 *
 938 * Returns 0, or a negative error number on failure.
 939 */
 940int
 941ext3_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
 942                      const char *name, const void *value, size_t value_len,
 943                      int flags)
 944{
 945        struct ext3_xattr_info i = {
 946                .name_index = name_index,
 947                .name = name,
 948                .value = value,
 949                .value_len = value_len,
 950
 951        };
 952        struct ext3_xattr_ibody_find is = {
 953                .s = { .not_found = -ENODATA, },
 954        };
 955        struct ext3_xattr_block_find bs = {
 956                .s = { .not_found = -ENODATA, },
 957        };
 958        int error;
 959
 960        if (!name)
 961                return -EINVAL;
 962        if (strlen(name) > 255)
 963                return -ERANGE;
 964        down_write(&EXT3_I(inode)->xattr_sem);
 965        error = ext3_get_inode_loc(inode, &is.iloc);
 966        if (error)
 967                goto cleanup;
 968
 969        error = ext3_journal_get_write_access(handle, is.iloc.bh);
 970        if (error)
 971                goto cleanup;
 972
 973        if (ext3_test_inode_state(inode, EXT3_STATE_NEW)) {
 974                struct ext3_inode *raw_inode = ext3_raw_inode(&is.iloc);
 975                memset(raw_inode, 0, EXT3_SB(inode->i_sb)->s_inode_size);
 976                ext3_clear_inode_state(inode, EXT3_STATE_NEW);
 977        }
 978
 979        error = ext3_xattr_ibody_find(inode, &i, &is);
 980        if (error)
 981                goto cleanup;
 982        if (is.s.not_found)
 983                error = ext3_xattr_block_find(inode, &i, &bs);
 984        if (error)
 985                goto cleanup;
 986        if (is.s.not_found && bs.s.not_found) {
 987                error = -ENODATA;
 988                if (flags & XATTR_REPLACE)
 989                        goto cleanup;
 990                error = 0;
 991                if (!value)
 992                        goto cleanup;
 993        } else {
 994                error = -EEXIST;
 995                if (flags & XATTR_CREATE)
 996                        goto cleanup;
 997        }
 998        if (!value) {
 999                if (!is.s.not_found)
1000                        error = ext3_xattr_ibody_set(handle, inode, &i, &is);
1001                else if (!bs.s.not_found)
1002                        error = ext3_xattr_block_set(handle, inode, &i, &bs);
1003        } else {
1004                error = ext3_xattr_ibody_set(handle, inode, &i, &is);
1005                if (!error && !bs.s.not_found) {
1006                        i.value = NULL;
1007                        error = ext3_xattr_block_set(handle, inode, &i, &bs);
1008                } else if (error == -ENOSPC) {
1009                        if (EXT3_I(inode)->i_file_acl && !bs.s.base) {
1010                                error = ext3_xattr_block_find(inode, &i, &bs);
1011                                if (error)
1012                                        goto cleanup;
1013                        }
1014                        error = ext3_xattr_block_set(handle, inode, &i, &bs);
1015                        if (error)
1016                                goto cleanup;
1017                        if (!is.s.not_found) {
1018                                i.value = NULL;
1019                                error = ext3_xattr_ibody_set(handle, inode, &i,
1020                                                             &is);
1021                        }
1022                }
1023        }
1024        if (!error) {
1025                ext3_xattr_update_super_block(handle, inode->i_sb);
1026                inode->i_ctime = CURRENT_TIME_SEC;
1027                error = ext3_mark_iloc_dirty(handle, inode, &is.iloc);
1028                /*
1029                 * The bh is consumed by ext3_mark_iloc_dirty, even with
1030                 * error != 0.
1031                 */
1032                is.iloc.bh = NULL;
1033                if (IS_SYNC(inode))
1034                        handle->h_sync = 1;
1035        }
1036
1037cleanup:
1038        brelse(is.iloc.bh);
1039        brelse(bs.bh);
1040        up_write(&EXT3_I(inode)->xattr_sem);
1041        return error;
1042}
1043
1044/*
1045 * ext3_xattr_set()
1046 *
1047 * Like ext3_xattr_set_handle, but start from an inode. This extended
1048 * attribute modification is a filesystem transaction by itself.
1049 *
1050 * Returns 0, or a negative error number on failure.
1051 */
1052int
1053ext3_xattr_set(struct inode *inode, int name_index, const char *name,
1054               const void *value, size_t value_len, int flags)
1055{
1056        handle_t *handle;
1057        int error, retries = 0;
1058
1059retry:
1060        handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
1061        if (IS_ERR(handle)) {
1062                error = PTR_ERR(handle);
1063        } else {
1064                int error2;
1065
1066                error = ext3_xattr_set_handle(handle, inode, name_index, name,
1067                                              value, value_len, flags);
1068                error2 = ext3_journal_stop(handle);
1069                if (error == -ENOSPC &&
1070                    ext3_should_retry_alloc(inode->i_sb, &retries))
1071                        goto retry;
1072                if (error == 0)
1073                        error = error2;
1074        }
1075
1076        return error;
1077}
1078
1079/*
1080 * ext3_xattr_delete_inode()
1081 *
1082 * Free extended attribute resources associated with this inode. This
1083 * is called immediately before an inode is freed. We have exclusive
1084 * access to the inode.
1085 */
1086void
1087ext3_xattr_delete_inode(handle_t *handle, struct inode *inode)
1088{
1089        struct buffer_head *bh = NULL;
1090
1091        if (!EXT3_I(inode)->i_file_acl)
1092                goto cleanup;
1093        bh = sb_bread(inode->i_sb, EXT3_I(inode)->i_file_acl);
1094        if (!bh) {
1095                ext3_error(inode->i_sb, __func__,
1096                        "inode %lu: block "E3FSBLK" read error", inode->i_ino,
1097                        EXT3_I(inode)->i_file_acl);
1098                goto cleanup;
1099        }
1100        if (BHDR(bh)->h_magic != cpu_to_le32(EXT3_XATTR_MAGIC) ||
1101            BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1102                ext3_error(inode->i_sb, __func__,
1103                        "inode %lu: bad block "E3FSBLK, inode->i_ino,
1104                        EXT3_I(inode)->i_file_acl);
1105                goto cleanup;
1106        }
1107        ext3_xattr_release_block(handle, inode, bh);
1108        EXT3_I(inode)->i_file_acl = 0;
1109
1110cleanup:
1111        brelse(bh);
1112}
1113
1114/*
1115 * ext3_xattr_put_super()
1116 *
1117 * This is called when a file system is unmounted.
1118 */
1119void
1120ext3_xattr_put_super(struct super_block *sb)
1121{
1122        mb_cache_shrink(sb->s_bdev);
1123}
1124
1125/*
1126 * ext3_xattr_cache_insert()
1127 *
1128 * Create a new entry in the extended attribute cache, and insert
1129 * it unless such an entry is already in the cache.
1130 *
1131 * Returns 0, or a negative error number on failure.
1132 */
1133static void
1134ext3_xattr_cache_insert(struct buffer_head *bh)
1135{
1136        __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1137        struct mb_cache_entry *ce;
1138        int error;
1139
1140        ce = mb_cache_entry_alloc(ext3_xattr_cache, GFP_NOFS);
1141        if (!ce) {
1142                ea_bdebug(bh, "out of memory");
1143                return;
1144        }
1145        error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
1146        if (error) {
1147                mb_cache_entry_free(ce);
1148                if (error == -EBUSY) {
1149                        ea_bdebug(bh, "already in cache");
1150                        error = 0;
1151                }
1152        } else {
1153                ea_bdebug(bh, "inserting [%x]", (int)hash);
1154                mb_cache_entry_release(ce);
1155        }
1156}
1157
1158/*
1159 * ext3_xattr_cmp()
1160 *
1161 * Compare two extended attribute blocks for equality.
1162 *
1163 * Returns 0 if the blocks are equal, 1 if they differ, and
1164 * a negative error number on errors.
1165 */
1166static int
1167ext3_xattr_cmp(struct ext3_xattr_header *header1,
1168               struct ext3_xattr_header *header2)
1169{
1170        struct ext3_xattr_entry *entry1, *entry2;
1171
1172        entry1 = ENTRY(header1+1);
1173        entry2 = ENTRY(header2+1);
1174        while (!IS_LAST_ENTRY(entry1)) {
1175                if (IS_LAST_ENTRY(entry2))
1176                        return 1;
1177                if (entry1->e_hash != entry2->e_hash ||
1178                    entry1->e_name_index != entry2->e_name_index ||
1179                    entry1->e_name_len != entry2->e_name_len ||
1180                    entry1->e_value_size != entry2->e_value_size ||
1181                    memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1182                        return 1;
1183                if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1184                        return -EIO;
1185                if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1186                           (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1187                           le32_to_cpu(entry1->e_value_size)))
1188                        return 1;
1189
1190                entry1 = EXT3_XATTR_NEXT(entry1);
1191                entry2 = EXT3_XATTR_NEXT(entry2);
1192        }
1193        if (!IS_LAST_ENTRY(entry2))
1194                return 1;
1195        return 0;
1196}
1197
1198/*
1199 * ext3_xattr_cache_find()
1200 *
1201 * Find an identical extended attribute block.
1202 *
1203 * Returns a pointer to the block found, or NULL if such a block was
1204 * not found or an error occurred.
1205 */
1206static struct buffer_head *
1207ext3_xattr_cache_find(struct inode *inode, struct ext3_xattr_header *header,
1208                      struct mb_cache_entry **pce)
1209{
1210        __u32 hash = le32_to_cpu(header->h_hash);
1211        struct mb_cache_entry *ce;
1212
1213        if (!header->h_hash)
1214                return NULL;  /* never share */
1215        ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1216again:
1217        ce = mb_cache_entry_find_first(ext3_xattr_cache, inode->i_sb->s_bdev,
1218                                       hash);
1219        while (ce) {
1220                struct buffer_head *bh;
1221
1222                if (IS_ERR(ce)) {
1223                        if (PTR_ERR(ce) == -EAGAIN)
1224                                goto again;
1225                        break;
1226                }
1227                bh = sb_bread(inode->i_sb, ce->e_block);
1228                if (!bh) {
1229                        ext3_error(inode->i_sb, __func__,
1230                                "inode %lu: block %lu read error",
1231                                inode->i_ino, (unsigned long) ce->e_block);
1232                } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1233                                EXT3_XATTR_REFCOUNT_MAX) {
1234                        ea_idebug(inode, "block %lu refcount %d>=%d",
1235                                  (unsigned long) ce->e_block,
1236                                  le32_to_cpu(BHDR(bh)->h_refcount),
1237                                          EXT3_XATTR_REFCOUNT_MAX);
1238                } else if (ext3_xattr_cmp(header, BHDR(bh)) == 0) {
1239                        *pce = ce;
1240                        return bh;
1241                }
1242                brelse(bh);
1243                ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
1244        }
1245        return NULL;
1246}
1247
1248#define NAME_HASH_SHIFT 5
1249#define VALUE_HASH_SHIFT 16
1250
1251/*
1252 * ext3_xattr_hash_entry()
1253 *
1254 * Compute the hash of an extended attribute.
1255 */
1256static inline void ext3_xattr_hash_entry(struct ext3_xattr_header *header,
1257                                         struct ext3_xattr_entry *entry)
1258{
1259        __u32 hash = 0;
1260        char *name = entry->e_name;
1261        int n;
1262
1263        for (n=0; n < entry->e_name_len; n++) {
1264                hash = (hash << NAME_HASH_SHIFT) ^
1265                       (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1266                       *name++;
1267        }
1268
1269        if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1270                __le32 *value = (__le32 *)((char *)header +
1271                        le16_to_cpu(entry->e_value_offs));
1272                for (n = (le32_to_cpu(entry->e_value_size) +
1273                     EXT3_XATTR_ROUND) >> EXT3_XATTR_PAD_BITS; n; n--) {
1274                        hash = (hash << VALUE_HASH_SHIFT) ^
1275                               (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1276                               le32_to_cpu(*value++);
1277                }
1278        }
1279        entry->e_hash = cpu_to_le32(hash);
1280}
1281
1282#undef NAME_HASH_SHIFT
1283#undef VALUE_HASH_SHIFT
1284
1285#define BLOCK_HASH_SHIFT 16
1286
1287/*
1288 * ext3_xattr_rehash()
1289 *
1290 * Re-compute the extended attribute hash value after an entry has changed.
1291 */
1292static void ext3_xattr_rehash(struct ext3_xattr_header *header,
1293                              struct ext3_xattr_entry *entry)
1294{
1295        struct ext3_xattr_entry *here;
1296        __u32 hash = 0;
1297
1298        ext3_xattr_hash_entry(header, entry);
1299        here = ENTRY(header+1);
1300        while (!IS_LAST_ENTRY(here)) {
1301                if (!here->e_hash) {
1302                        /* Block is not shared if an entry's hash value == 0 */
1303                        hash = 0;
1304                        break;
1305                }
1306                hash = (hash << BLOCK_HASH_SHIFT) ^
1307                       (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1308                       le32_to_cpu(here->e_hash);
1309                here = EXT3_XATTR_NEXT(here);
1310        }
1311        header->h_hash = cpu_to_le32(hash);
1312}
1313
1314#undef BLOCK_HASH_SHIFT
1315
1316int __init
1317init_ext3_xattr(void)
1318{
1319        ext3_xattr_cache = mb_cache_create("ext3_xattr", 6);
1320        if (!ext3_xattr_cache)
1321                return -ENOMEM;
1322        return 0;
1323}
1324
1325void
1326exit_ext3_xattr(void)
1327{
1328        if (ext3_xattr_cache)
1329                mb_cache_destroy(ext3_xattr_cache);
1330        ext3_xattr_cache = NULL;
1331}
1332
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