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   1 /*
   2  * linux/fs/ext4/xattr.c
   3  *
   4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   5  *
   6  * Fix by Harrison Xing <harrison@mountainviewdata.com>.
   7  * Ext4 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  * EXT4_I(inode)->i_file_acl is protected by EXT4_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/ext4_jbd2.h>
  57 #include <linux/ext4_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 ext4_xattr_header *)((bh)->b_data))
  65 #define ENTRY(ptr) ((struct ext4_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 ext4_xattr_ibody_header *) \
  71                 ((void *)raw_inode + \
  72                  EXT4_GOOD_OLD_INODE_SIZE + \
  73                  EXT4_I(inode)->i_extra_isize))
  74 #define IFIRST(hdr) ((struct ext4_xattr_entry *)((hdr)+1))
  75
  76 #ifdef EXT4_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 ext4_xattr_cache_insert(struct buffer_head *);
  97 static struct buffer_head *ext4_xattr_cache_find(struct inode *,
  98                                                  struct ext4_xattr_header *,
  99                                                  struct mb_cache_entry **);
 100 static void ext4_xattr_rehash(struct ext4_xattr_header *,
 101                               struct ext4_xattr_entry *);
 102
 103 static struct mb_cache *ext4_xattr_cache;
 104
 105 static struct xattr_handler *ext4_xattr_handler_map[] = {
 106         [EXT4_XATTR_INDEX_USER]              = &ext4_xattr_user_handler,
 107 #ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
 108         [EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &ext4_xattr_acl_access_handler,
 109         [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext4_xattr_acl_default_handler,
 110 #endif
 111         [EXT4_XATTR_INDEX_TRUSTED]           = &ext4_xattr_trusted_handler,
 112 #ifdef CONFIG_EXT4DEV_FS_SECURITY
 113         [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
 114 #endif
 115 };
 116
 117 struct xattr_handler *ext4_xattr_handlers[] = {
 118         &ext4_xattr_user_handler,
 119         &ext4_xattr_trusted_handler,
 120 #ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
 121         &ext4_xattr_acl_access_handler,
 122         &ext4_xattr_acl_default_handler,
 123 #endif
 124 #ifdef CONFIG_EXT4DEV_FS_SECURITY
 125         &ext4_xattr_security_handler,
 126 #endif
 127         NULL
 128 };
 129
 130 static inline struct xattr_handler *
 131 ext4_xattr_handler(int name_index)
 132 {
 133         struct xattr_handler *handler = NULL;
 134
 135         if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
 136                 handler = ext4_xattr_handler_map[name_index];
 137         return handler;
 138 }
 139
 140 /*
 141  * Inode operation listxattr()
 142  *
 143  * dentry->d_inode->i_mutex: don't care
 144  */
 145 ssize_t
 146 ext4_listxattr(struct dentry *dentry, char *buffer, size_t size)
 147 {
 148         return ext4_xattr_list(dentry->d_inode, buffer, size);
 149 }
 150
 151 static int
 152 ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end)
 153 {
 154         while (!IS_LAST_ENTRY(entry)) {
 155                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(entry);
 156                 if ((void *)next >= end)
 157                         return -EIO;
 158                 entry = next;
 159         }
 160         return 0;
 161 }
 162
 163 static inline int
 164 ext4_xattr_check_block(struct buffer_head *bh)
 165 {
 166         int error;
 167
 168         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
 169             BHDR(bh)->h_blocks != cpu_to_le32(1))
 170                 return -EIO;
 171         error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
 172         return error;
 173 }
 174
 175 static inline int
 176 ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size)
 177 {
 178         size_t value_size = le32_to_cpu(entry->e_value_size);
 179
 180         if (entry->e_value_block != 0 || value_size > size ||
 181             le16_to_cpu(entry->e_value_offs) + value_size > size)
 182                 return -EIO;
 183         return 0;
 184 }
 185
 186 static int
 187 ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
 188                       const char *name, size_t size, int sorted)
 189 {
 190         struct ext4_xattr_entry *entry;
 191         size_t name_len;
 192         int cmp = 1;
 193
 194         if (name == NULL)
 195                 return -EINVAL;
 196         name_len = strlen(name);
 197         entry = *pentry;
 198         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 199                 cmp = name_index - entry->e_name_index;
 200                 if (!cmp)
 201                         cmp = name_len - entry->e_name_len;
 202                 if (!cmp)
 203                         cmp = memcmp(name, entry->e_name, name_len);
 204                 if (cmp <= 0 && (sorted || cmp == 0))
 205                         break;
 206         }
 207         *pentry = entry;
 208         if (!cmp && ext4_xattr_check_entry(entry, size))
 209                         return -EIO;
 210         return cmp ? -ENODATA : 0;
 211 }
 212
 213 static int
 214 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
 215                      void *buffer, size_t buffer_size)
 216 {
 217         struct buffer_head *bh = NULL;
 218         struct ext4_xattr_entry *entry;
 219         size_t size;
 220         int error;
 221
 222         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 223                   name_index, name, buffer, (long)buffer_size);
 224
 225         error = -ENODATA;
 226         if (!EXT4_I(inode)->i_file_acl)
 227                 goto cleanup;
 228         ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl);
 229         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 230         if (!bh)
 231                 goto cleanup;
 232         ea_bdebug(bh, "b_count=%d, refcount=%d",
 233                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 234         if (ext4_xattr_check_block(bh)) {
 235 bad_block:      ext4_error(inode->i_sb, __FUNCTION__,
 236                            "inode %lu: bad block %llu", inode->i_ino,
 237                            EXT4_I(inode)->i_file_acl);
 238                 error = -EIO;
 239                 goto cleanup;
 240         }
 241         ext4_xattr_cache_insert(bh);
 242         entry = BFIRST(bh);
 243         error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
 244         if (error == -EIO)
 245                 goto bad_block;
 246         if (error)
 247                 goto cleanup;
 248         size = le32_to_cpu(entry->e_value_size);
 249         if (buffer) {
 250                 error = -ERANGE;
 251                 if (size > buffer_size)
 252                         goto cleanup;
 253                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
 254                        size);
 255         }
 256         error = size;
 257
 258 cleanup:
 259         brelse(bh);
 260         return error;
 261 }
 262
 263 static int
 264 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 265                      void *buffer, size_t buffer_size)
 266 {
 267         struct ext4_xattr_ibody_header *header;
 268         struct ext4_xattr_entry *entry;
 269         struct ext4_inode *raw_inode;
 270         struct ext4_iloc iloc;
 271         size_t size;
 272         void *end;
 273         int error;
 274
 275         if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR))
 276                 return -ENODATA;
 277         error = ext4_get_inode_loc(inode, &iloc);
 278         if (error)
 279                 return error;
 280         raw_inode = ext4_raw_inode(&iloc);
 281         header = IHDR(inode, raw_inode);
 282         entry = IFIRST(header);
 283         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 284         error = ext4_xattr_check_names(entry, end);
 285         if (error)
 286                 goto cleanup;
 287         error = ext4_xattr_find_entry(&entry, name_index, name,
 288                                       end - (void *)entry, 0);
 289         if (error)
 290                 goto cleanup;
 291         size = le32_to_cpu(entry->e_value_size);
 292         if (buffer) {
 293                 error = -ERANGE;
 294                 if (size > buffer_size)
 295                         goto cleanup;
 296                 memcpy(buffer, (void *)IFIRST(header) +
 297                        le16_to_cpu(entry->e_value_offs), size);
 298         }
 299         error = size;
 300
 301 cleanup:
 302         brelse(iloc.bh);
 303         return error;
 304 }
 305
 306 /*
 307  * ext4_xattr_get()
 308  *
 309  * Copy an extended attribute into the buffer
 310  * provided, or compute the buffer size required.
 311  * Buffer is NULL to compute the size of the buffer required.
 312  *
 313  * Returns a negative error number on failure, or the number of bytes
 314  * used / required on success.
 315  */
 316 int
 317 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
 318                void *buffer, size_t buffer_size)
 319 {
 320         int error;
 321
 322         down_read(&EXT4_I(inode)->xattr_sem);
 323         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
 324                                      buffer_size);
 325         if (error == -ENODATA)
 326                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
 327                                              buffer_size);
 328         up_read(&EXT4_I(inode)->xattr_sem);
 329         return error;
 330 }
 331
 332 static int
 333 ext4_xattr_list_entries(struct inode *inode, struct ext4_xattr_entry *entry,
 334                         char *buffer, size_t buffer_size)
 335 {
 336         size_t rest = buffer_size;
 337
 338         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 339                 struct xattr_handler *handler =
 340                         ext4_xattr_handler(entry->e_name_index);
 341
 342                 if (handler) {
 343                         size_t size = handler->list(inode, buffer, rest,
 344                                                     entry->e_name,
 345                                                     entry->e_name_len);
 346                         if (buffer) {
 347                                 if (size > rest)
 348                                         return -ERANGE;
 349                                 buffer += size;
 350                         }
 351                         rest -= size;
 352                 }
 353         }
 354         return buffer_size - rest;
 355 }
 356
 357 static int
 358 ext4_xattr_block_list(struct inode *inode, char *buffer, size_t buffer_size)
 359 {
 360         struct buffer_head *bh = NULL;
 361         int error;
 362
 363         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 364                   buffer, (long)buffer_size);
 365
 366         error = 0;
 367         if (!EXT4_I(inode)->i_file_acl)
 368                 goto cleanup;
 369         ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl);
 370         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 371         error = -EIO;
 372         if (!bh)
 373                 goto cleanup;
 374         ea_bdebug(bh, "b_count=%d, refcount=%d",
 375                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 376         if (ext4_xattr_check_block(bh)) {
 377                 ext4_error(inode->i_sb, __FUNCTION__,
 378                            "inode %lu: bad block %llu", inode->i_ino,
 379                            EXT4_I(inode)->i_file_acl);
 380                 error = -EIO;
 381                 goto cleanup;
 382         }
 383         ext4_xattr_cache_insert(bh);
 384         error = ext4_xattr_list_entries(inode, BFIRST(bh), buffer, buffer_size);
 385
 386 cleanup:
 387         brelse(bh);
 388
 389         return error;
 390 }
 391
 392 static int
 393 ext4_xattr_ibody_list(struct inode *inode, char *buffer, size_t buffer_size)
 394 {
 395         struct ext4_xattr_ibody_header *header;
 396         struct ext4_inode *raw_inode;
 397         struct ext4_iloc iloc;
 398         void *end;
 399         int error;
 400
 401         if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR))
 402                 return 0;
 403         error = ext4_get_inode_loc(inode, &iloc);
 404         if (error)
 405                 return error;
 406         raw_inode = ext4_raw_inode(&iloc);
 407         header = IHDR(inode, raw_inode);
 408         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 409         error = ext4_xattr_check_names(IFIRST(header), end);
 410         if (error)
 411                 goto cleanup;
 412         error = ext4_xattr_list_entries(inode, IFIRST(header),
 413                                         buffer, buffer_size);
 414
 415 cleanup:
 416         brelse(iloc.bh);
 417         return error;
 418 }
 419
 420 /*
 421  * ext4_xattr_list()
 422  *
 423  * Copy a list of attribute names into the buffer
 424  * provided, or compute the buffer size required.
 425  * Buffer is NULL to compute the size of the buffer required.
 426  *
 427  * Returns a negative error number on failure, or the number of bytes
 428  * used / required on success.
 429  */
 430 int
 431 ext4_xattr_list(struct inode *inode, char *buffer, size_t buffer_size)
 432 {
 433         int i_error, b_error;
 434
 435         down_read(&EXT4_I(inode)->xattr_sem);
 436         i_error = ext4_xattr_ibody_list(inode, buffer, buffer_size);
 437         if (i_error < 0) {
 438                 b_error = 0;
 439         } else {
 440                 if (buffer) {
 441                         buffer += i_error;
 442                         buffer_size -= i_error;
 443                 }
 444                 b_error = ext4_xattr_block_list(inode, buffer, buffer_size);
 445                 if (b_error < 0)
 446                         i_error = 0;
 447         }
 448         up_read(&EXT4_I(inode)->xattr_sem);
 449         return i_error + b_error;
 450 }
 451
 452 /*
 453  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 454  * not set, set it.
 455  */
 456 static void ext4_xattr_update_super_block(handle_t *handle,
 457                                           struct super_block *sb)
 458 {
 459         if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR))
 460                 return;
 461
 462         if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
 463                 EXT4_SET_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR);
 464                 sb->s_dirt = 1;
 465                 ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh);
 466         }
 467 }
 468
 469 /*
 470  * Release the xattr block BH: If the reference count is > 1, decrement
 471  * it; otherwise free the block.
 472  */
 473 static void
 474 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
 475                          struct buffer_head *bh)
 476 {
 477         struct mb_cache_entry *ce = NULL;
 478
 479         ce = mb_cache_entry_get(ext4_xattr_cache, bh->b_bdev, bh->b_blocknr);
 480         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
 481                 ea_bdebug(bh, "refcount now=0; freeing");
 482                 if (ce)
 483                         mb_cache_entry_free(ce);
 484                 ext4_free_blocks(handle, inode, bh->b_blocknr, 1);
 485                 get_bh(bh);
 486                 ext4_forget(handle, 1, inode, bh, bh->b_blocknr);
 487         } else {
 488                 if (ext4_journal_get_write_access(handle, bh) == 0) {
 489                         lock_buffer(bh);
 490                         BHDR(bh)->h_refcount = cpu_to_le32(
 491                                 le32_to_cpu(BHDR(bh)->h_refcount) - 1);
 492                         ext4_journal_dirty_metadata(handle, bh);
 493                         if (IS_SYNC(inode))
 494                                 handle->h_sync = 1;
 495                         DQUOT_FREE_BLOCK(inode, 1);
 496                         unlock_buffer(bh);
 497                         ea_bdebug(bh, "refcount now=%d; releasing",
 498                                   le32_to_cpu(BHDR(bh)->h_refcount));
 499                 }
 500                 if (ce)
 501                         mb_cache_entry_release(ce);
 502         }
 503 }
 504
 505 struct ext4_xattr_info {
 506         int name_index;
 507         const char *name;
 508         const void *value;
 509         size_t value_len;
 510 };
 511
 512 struct ext4_xattr_search {
 513         struct ext4_xattr_entry *first;
 514         void *base;
 515         void *end;
 516         struct ext4_xattr_entry *here;
 517         int not_found;
 518 };
 519
 520 static int
 521 ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
 522 {
 523         struct ext4_xattr_entry *last;
 524         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
 525
 526         /* Compute min_offs and last. */
 527         last = s->first;
 528         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 529                 if (!last->e_value_block && last->e_value_size) {
 530                         size_t offs = le16_to_cpu(last->e_value_offs);
 531                         if (offs < min_offs)
 532                                 min_offs = offs;
 533                 }
 534         }
 535         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
 536         if (!s->not_found) {
 537                 if (!s->here->e_value_block && s->here->e_value_size) {
 538                         size_t size = le32_to_cpu(s->here->e_value_size);
 539                         free += EXT4_XATTR_SIZE(size);
 540                 }
 541                 free += EXT4_XATTR_LEN(name_len);
 542         }
 543         if (i->value) {
 544                 if (free < EXT4_XATTR_SIZE(i->value_len) ||
 545                     free < EXT4_XATTR_LEN(name_len) +
 546                            EXT4_XATTR_SIZE(i->value_len))
 547                         return -ENOSPC;
 548         }
 549
 550         if (i->value && s->not_found) {
 551                 /* Insert the new name. */
 552                 size_t size = EXT4_XATTR_LEN(name_len);
 553                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
 554                 memmove((void *)s->here + size, s->here, rest);
 555                 memset(s->here, 0, size);
 556                 s->here->e_name_index = i->name_index;
 557                 s->here->e_name_len = name_len;
 558                 memcpy(s->here->e_name, i->name, name_len);
 559         } else {
 560                 if (!s->here->e_value_block && s->here->e_value_size) {
 561                         void *first_val = s->base + min_offs;
 562                         size_t offs = le16_to_cpu(s->here->e_value_offs);
 563                         void *val = s->base + offs;
 564                         size_t size = EXT4_XATTR_SIZE(
 565                                 le32_to_cpu(s->here->e_value_size));
 566
 567                         if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
 568                                 /* The old and the new value have the same
 569                                    size. Just replace. */
 570                                 s->here->e_value_size =
 571                                         cpu_to_le32(i->value_len);
 572                                 memset(val + size - EXT4_XATTR_PAD, 0,
 573                                        EXT4_XATTR_PAD); /* Clear pad bytes. */
 574                                 memcpy(val, i->value, i->value_len);
 575                                 return 0;
 576                         }
 577
 578                         /* Remove the old value. */
 579                         memmove(first_val + size, first_val, val - first_val);
 580                         memset(first_val, 0, size);
 581                         s->here->e_value_size = 0;
 582                         s->here->e_value_offs = 0;
 583                         min_offs += size;
 584
 585                         /* Adjust all value offsets. */
 586                         last = s->first;
 587                         while (!IS_LAST_ENTRY(last)) {
 588                                 size_t o = le16_to_cpu(last->e_value_offs);
 589                                 if (!last->e_value_block &&
 590                                     last->e_value_size && o < offs)
 591                                         last->e_value_offs =
 592                                                 cpu_to_le16(o + size);
 593                                 last = EXT4_XATTR_NEXT(last);
 594                         }
 595                 }
 596                 if (!i->value) {
 597                         /* Remove the old name. */
 598                         size_t size = EXT4_XATTR_LEN(name_len);
 599                         last = ENTRY((void *)last - size);
 600                         memmove(s->here, (void *)s->here + size,
 601                                 (void *)last - (void *)s->here + sizeof(__u32));
 602                         memset(last, 0, size);
 603                 }
 604         }
 605
 606         if (i->value) {
 607                 /* Insert the new value. */
 608                 s->here->e_value_size = cpu_to_le32(i->value_len);
 609                 if (i->value_len) {
 610                         size_t size = EXT4_XATTR_SIZE(i->value_len);
 611                         void *val = s->base + min_offs - size;
 612                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
 613                         memset(val + size - EXT4_XATTR_PAD, 0,
 614                                EXT4_XATTR_PAD); /* Clear the pad bytes. */
 615                         memcpy(val, i->value, i->value_len);
 616                 }
 617         }
 618         return 0;
 619 }
 620
 621 struct ext4_xattr_block_find {
 622         struct ext4_xattr_search s;
 623         struct buffer_head *bh;
 624 };
 625
 626 static int
 627 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
 628                       struct ext4_xattr_block_find *bs)
 629 {
 630         struct super_block *sb = inode->i_sb;
 631         int error;
 632
 633         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
 634                   i->name_index, i->name, i->value, (long)i->value_len);
 635
 636         if (EXT4_I(inode)->i_file_acl) {
 637                 /* The inode already has an extended attribute block. */
 638                 bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);
 639                 error = -EIO;
 640                 if (!bs->bh)
 641                         goto cleanup;
 642                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
 643                         atomic_read(&(bs->bh->b_count)),
 644                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
 645                 if (ext4_xattr_check_block(bs->bh)) {
 646                         ext4_error(sb, __FUNCTION__,
 647                                 "inode %lu: bad block %llu", inode->i_ino,
 648                                 EXT4_I(inode)->i_file_acl);
 649                         error = -EIO;
 650                         goto cleanup;
 651                 }
 652                 /* Find the named attribute. */
 653                 bs->s.base = BHDR(bs->bh);
 654                 bs->s.first = BFIRST(bs->bh);
 655                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
 656                 bs->s.here = bs->s.first;
 657                 error = ext4_xattr_find_entry(&bs->s.here, i->name_index,
 658                                               i->name, bs->bh->b_size, 1);
 659                 if (error && error != -ENODATA)
 660                         goto cleanup;
 661                 bs->s.not_found = error;
 662         }
 663         error = 0;
 664
 665 cleanup:
 666         return error;
 667 }
 668
 669 static int
 670 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
 671                      struct ext4_xattr_info *i,
 672                      struct ext4_xattr_block_find *bs)
 673 {
 674         struct super_block *sb = inode->i_sb;
 675         struct buffer_head *new_bh = NULL;
 676         struct ext4_xattr_search *s = &bs->s;
 677         struct mb_cache_entry *ce = NULL;
 678         int error;
 679
 680 #define header(x) ((struct ext4_xattr_header *)(x))
 681
 682         if (i->value && i->value_len > sb->s_blocksize)
 683                 return -ENOSPC;
 684         if (s->base) {
 685                 ce = mb_cache_entry_get(ext4_xattr_cache, bs->bh->b_bdev,
 686                                         bs->bh->b_blocknr);
 687                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 688                         if (ce) {
 689                                 mb_cache_entry_free(ce);
 690                                 ce = NULL;
 691                         }
 692                         ea_bdebug(bs->bh, "modifying in-place");
 693                         error = ext4_journal_get_write_access(handle, bs->bh);
 694                         if (error)
 695                                 goto cleanup;
 696                         lock_buffer(bs->bh);
 697                         error = ext4_xattr_set_entry(i, s);
 698                         if (!error) {
 699                                 if (!IS_LAST_ENTRY(s->first))
 700                                         ext4_xattr_rehash(header(s->base),
 701                                                           s->here);
 702                                 ext4_xattr_cache_insert(bs->bh);
 703                         }
 704                         unlock_buffer(bs->bh);
 705                         if (error == -EIO)
 706                                 goto bad_block;
 707                         if (!error)
 708                                 error = ext4_journal_dirty_metadata(handle,
 709                                                                     bs->bh);
 710                         if (error)
 711                                 goto cleanup;
 712                         goto inserted;
 713                 } else {
 714                         int offset = (char *)s->here - bs->bh->b_data;
 715
 716                         if (ce) {
 717                                 mb_cache_entry_release(ce);
 718                                 ce = NULL;
 719                         }
 720                         ea_bdebug(bs->bh, "cloning");
 721                         s->base = kmalloc(bs->bh->b_size, GFP_KERNEL);
 722                         error = -ENOMEM;
 723                         if (s->base == NULL)
 724                                 goto cleanup;
 725                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 726                         s->first = ENTRY(header(s->base)+1);
 727                         header(s->base)->h_refcount = cpu_to_le32(1);
 728                         s->here = ENTRY(s->base + offset);
 729                         s->end = s->base + bs->bh->b_size;
 730                 }
 731         } else {
 732                 /* Allocate a buffer where we construct the new block. */
 733                 s->base = kmalloc(sb->s_blocksize, GFP_KERNEL);
 734                 /* assert(header == s->base) */
 735                 error = -ENOMEM;
 736                 if (s->base == NULL)
 737                         goto cleanup;
 738                 memset(s->base, 0, sb->s_blocksize);
 739                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
 740                 header(s->base)->h_blocks = cpu_to_le32(1);
 741                 header(s->base)->h_refcount = cpu_to_le32(1);
 742                 s->first = ENTRY(header(s->base)+1);
 743                 s->here = ENTRY(header(s->base)+1);
 744                 s->end = s->base + sb->s_blocksize;
 745         }
 746
 747         error = ext4_xattr_set_entry(i, s);
 748         if (error == -EIO)
 749                 goto bad_block;
 750         if (error)
 751                 goto cleanup;
 752         if (!IS_LAST_ENTRY(s->first))
 753                 ext4_xattr_rehash(header(s->base), s->here);
 754
 755 inserted:
 756         if (!IS_LAST_ENTRY(s->first)) {
 757                 new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);
 758                 if (new_bh) {
 759                         /* We found an identical block in the cache. */
 760                         if (new_bh == bs->bh)
 761                                 ea_bdebug(new_bh, "keeping");
 762                         else {
 763                                 /* The old block is released after updating
 764                                    the inode. */
 765                                 error = -EDQUOT;
 766                                 if (DQUOT_ALLOC_BLOCK(inode, 1))
 767                                         goto cleanup;
 768                                 error = ext4_journal_get_write_access(handle,
 769                                                                       new_bh);
 770                                 if (error)
 771                                         goto cleanup_dquot;
 772                                 lock_buffer(new_bh);
 773                                 BHDR(new_bh)->h_refcount = cpu_to_le32(1 +
 774                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 775                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
 776                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 777                                 unlock_buffer(new_bh);
 778                                 error = ext4_journal_dirty_metadata(handle,
 779                                                                     new_bh);
 780                                 if (error)
 781                                         goto cleanup_dquot;
 782                         }
 783                         mb_cache_entry_release(ce);
 784                         ce = NULL;
 785                 } else if (bs->bh && s->base == bs->bh->b_data) {
 786                         /* We were modifying this block in-place. */
 787                         ea_bdebug(bs->bh, "keeping this block");
 788                         new_bh = bs->bh;
 789                         get_bh(new_bh);
 790                 } else {
 791                         /* We need to allocate a new block */
 792                         ext4_fsblk_t goal = le32_to_cpu(
 793                                         EXT4_SB(sb)->s_es->s_first_data_block) +
 794                                 (ext4_fsblk_t)EXT4_I(inode)->i_block_group *
 795                                 EXT4_BLOCKS_PER_GROUP(sb);
 796                         ext4_fsblk_t block = ext4_new_block(handle, inode,
 797                                                         goal, &error);
 798                         if (error)
 799                                 goto cleanup;
 800                         ea_idebug(inode, "creating block %d", block);
 801
 802                         new_bh = sb_getblk(sb, block);
 803                         if (!new_bh) {
 804 getblk_failed:
 805                                 ext4_free_blocks(handle, inode, block, 1);
 806                                 error = -EIO;
 807                                 goto cleanup;
 808                         }
 809                         lock_buffer(new_bh);
 810                         error = ext4_journal_get_create_access(handle, new_bh);
 811                         if (error) {
 812                                 unlock_buffer(new_bh);
 813                                 goto getblk_failed;
 814                         }
 815                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
 816                         set_buffer_uptodate(new_bh);
 817                         unlock_buffer(new_bh);
 818                         ext4_xattr_cache_insert(new_bh);
 819                         error = ext4_journal_dirty_metadata(handle, new_bh);
 820                         if (error)
 821                                 goto cleanup;
 822                 }
 823         }
 824
 825         /* Update the inode. */
 826         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
 827
 828         /* Drop the previous xattr block. */
 829         if (bs->bh && bs->bh != new_bh)
 830                 ext4_xattr_release_block(handle, inode, bs->bh);
 831         error = 0;
 832
 833 cleanup:
 834         if (ce)
 835                 mb_cache_entry_release(ce);
 836         brelse(new_bh);
 837         if (!(bs->bh && s->base == bs->bh->b_data))
 838                 kfree(s->base);
 839
 840         return error;
 841
 842 cleanup_dquot:
 843         DQUOT_FREE_BLOCK(inode, 1);
 844         goto cleanup;
 845
 846 bad_block:
 847         ext4_error(inode->i_sb, __FUNCTION__,
 848                    "inode %lu: bad block %llu", inode->i_ino,
 849                    EXT4_I(inode)->i_file_acl);
 850         goto cleanup;
 851
 852 #undef header
 853 }
 854
 855 struct ext4_xattr_ibody_find {
 856         struct ext4_xattr_search s;
 857         struct ext4_iloc iloc;
 858 };
 859
 860 static int
 861 ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
 862                       struct ext4_xattr_ibody_find *is)
 863 {
 864         struct ext4_xattr_ibody_header *header;
 865         struct ext4_inode *raw_inode;
 866         int error;
 867
 868         if (EXT4_I(inode)->i_extra_isize == 0)
 869                 return 0;
 870         raw_inode = ext4_raw_inode(&is->iloc);
 871         header = IHDR(inode, raw_inode);
 872         is->s.base = is->s.first = IFIRST(header);
 873         is->s.here = is->s.first;
 874         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 875         if (EXT4_I(inode)->i_state & EXT4_STATE_XATTR) {
 876                 error = ext4_xattr_check_names(IFIRST(header), is->s.end);
 877                 if (error)
 878                         return error;
 879                 /* Find the named attribute. */
 880                 error = ext4_xattr_find_entry(&is->s.here, i->name_index,
 881                                               i->name, is->s.end -
 882                                               (void *)is->s.base, 0);
 883                 if (error && error != -ENODATA)
 884                         return error;
 885                 is->s.not_found = error;
 886         }
 887         return 0;
 888 }
 889
 890 static int
 891 ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
 892                      struct ext4_xattr_info *i,
 893                      struct ext4_xattr_ibody_find *is)
 894 {
 895         struct ext4_xattr_ibody_header *header;
 896         struct ext4_xattr_search *s = &is->s;
 897         int error;
 898
 899         if (EXT4_I(inode)->i_extra_isize == 0)
 900                 return -ENOSPC;
 901         error = ext4_xattr_set_entry(i, s);
 902         if (error)
 903                 return error;
 904         header = IHDR(inode, ext4_raw_inode(&is->iloc));
 905         if (!IS_LAST_ENTRY(s->first)) {
 906                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
 907                 EXT4_I(inode)->i_state |= EXT4_STATE_XATTR;
 908         } else {
 909                 header->h_magic = cpu_to_le32(0);
 910                 EXT4_I(inode)->i_state &= ~EXT4_STATE_XATTR;
 911         }
 912         return 0;
 913 }
 914
 915 /*
 916  * ext4_xattr_set_handle()
 917  *
 918  * Create, replace or remove an extended attribute for this inode. Buffer
 919  * is NULL to remove an existing extended attribute, and non-NULL to
 920  * either replace an existing extended attribute, or create a new extended
 921  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 922  * specify that an extended attribute must exist and must not exist
 923  * previous to the call, respectively.
 924  *
 925  * Returns 0, or a negative error number on failure.
 926  */
 927 int
 928 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
 929                       const char *name, const void *value, size_t value_len,
 930                       int flags)
 931 {
 932         struct ext4_xattr_info i = {
 933                 .name_index = name_index,
 934                 .name = name,
 935                 .value = value,
 936                 .value_len = value_len,
 937
 938         };
 939         struct ext4_xattr_ibody_find is = {
 940                 .s = { .not_found = -ENODATA, },
 941         };
 942         struct ext4_xattr_block_find bs = {
 943                 .s = { .not_found = -ENODATA, },
 944         };
 945         int error;
 946
 947         if (!name)
 948                 return -EINVAL;
 949         if (strlen(name) > 255)
 950                 return -ERANGE;
 951         down_write(&EXT4_I(inode)->xattr_sem);
 952         error = ext4_get_inode_loc(inode, &is.iloc);
 953         if (error)
 954                 goto cleanup;
 955
 956         if (EXT4_I(inode)->i_state & EXT4_STATE_NEW) {
 957                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
 958                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
 959                 EXT4_I(inode)->i_state &= ~EXT4_STATE_NEW;
 960         }
 961
 962         error = ext4_xattr_ibody_find(inode, &i, &is);
 963         if (error)
 964                 goto cleanup;
 965         if (is.s.not_found)
 966                 error = ext4_xattr_block_find(inode, &i, &bs);
 967         if (error)
 968                 goto cleanup;
 969         if (is.s.not_found && bs.s.not_found) {
 970                 error = -ENODATA;
 971                 if (flags & XATTR_REPLACE)
 972                         goto cleanup;
 973                 error = 0;
 974                 if (!value)
 975                         goto cleanup;
 976         } else {
 977                 error = -EEXIST;
 978                 if (flags & XATTR_CREATE)
 979                         goto cleanup;
 980         }
 981         error = ext4_journal_get_write_access(handle, is.iloc.bh);
 982         if (error)
 983                 goto cleanup;
 984         if (!value) {
 985                 if (!is.s.not_found)
 986                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
 987                 else if (!bs.s.not_found)
 988                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
 989         } else {
 990                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
 991                 if (!error && !bs.s.not_found) {
 992                         i.value = NULL;
 993                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
 994                 } else if (error == -ENOSPC) {
 995                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
 996                         if (error)
 997                                 goto cleanup;
 998                         if (!is.s.not_found) {
 999                                 i.value = NULL;
1000                                 error = ext4_xattr_ibody_set(handle, inode, &i,
1001                                                              &is);
1002                         }
1003                 }
1004         }
1005         if (!error) {
1006                 ext4_xattr_update_super_block(handle, inode->i_sb);
1007                 inode->i_ctime = CURRENT_TIME_SEC;
1008                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
1009                 /*
1010                  * The bh is consumed by ext4_mark_iloc_dirty, even with
1011                  * error != 0.
1012                  */
1013                 is.iloc.bh = NULL;
1014                 if (IS_SYNC(inode))
1015                         handle->h_sync = 1;
1016         }
1017
1018 cleanup:
1019         brelse(is.iloc.bh);
1020         brelse(bs.bh);
1021         up_write(&EXT4_I(inode)->xattr_sem);
1022         return error;
1023 }
1024
1025 /*
1026  * ext4_xattr_set()
1027  *
1028  * Like ext4_xattr_set_handle, but start from an inode. This extended
1029  * attribute modification is a filesystem transaction by itself.
1030  *
1031  * Returns 0, or a negative error number on failure.
1032  */
1033 int
1034 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
1035                const void *value, size_t value_len, int flags)
1036 {
1037         handle_t *handle;
1038         int error, retries = 0;
1039
1040 retry:
1041         handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
1042         if (IS_ERR(handle)) {
1043                 error = PTR_ERR(handle);
1044         } else {
1045                 int error2;
1046
1047                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
1048                                               value, value_len, flags);
1049                 error2 = ext4_journal_stop(handle);
1050                 if (error == -ENOSPC &&
1051                     ext4_should_retry_alloc(inode->i_sb, &retries))
1052                         goto retry;
1053                 if (error == 0)
1054                         error = error2;
1055         }
1056
1057         return error;
1058 }
1059
1060 /*
1061  * ext4_xattr_delete_inode()
1062  *
1063  * Free extended attribute resources associated with this inode. This
1064  * is called immediately before an inode is freed. We have exclusive
1065  * access to the inode.
1066  */
1067 void
1068 ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)
1069 {
1070         struct buffer_head *bh = NULL;
1071
1072         if (!EXT4_I(inode)->i_file_acl)
1073                 goto cleanup;
1074         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1075         if (!bh) {
1076                 ext4_error(inode->i_sb, __FUNCTION__,
1077                         "inode %lu: block %llu read error", inode->i_ino,
1078                         EXT4_I(inode)->i_file_acl);
1079                 goto cleanup;
1080         }
1081         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
1082             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1083                 ext4_error(inode->i_sb, __FUNCTION__,
1084                         "inode %lu: bad block %llu", inode->i_ino,
1085                         EXT4_I(inode)->i_file_acl);
1086                 goto cleanup;
1087         }
1088         ext4_xattr_release_block(handle, inode, bh);
1089         EXT4_I(inode)->i_file_acl = 0;
1090
1091 cleanup:
1092         brelse(bh);
1093 }
1094
1095 /*
1096  * ext4_xattr_put_super()
1097  *
1098  * This is called when a file system is unmounted.
1099  */
1100 void
1101 ext4_xattr_put_super(struct super_block *sb)
1102 {
1103         mb_cache_shrink(sb->s_bdev);
1104 }
1105
1106 /*
1107  * ext4_xattr_cache_insert()
1108  *
1109  * Create a new entry in the extended attribute cache, and insert
1110  * it unless such an entry is already in the cache.
1111  *
1112  * Returns 0, or a negative error number on failure.
1113  */
1114 static void
1115 ext4_xattr_cache_insert(struct buffer_head *bh)
1116 {
1117         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1118         struct mb_cache_entry *ce;
1119         int error;
1120
1121         ce = mb_cache_entry_alloc(ext4_xattr_cache);
1122         if (!ce) {
1123                 ea_bdebug(bh, "out of memory");
1124                 return;
1125         }
1126         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
1127         if (error) {
1128                 mb_cache_entry_free(ce);
1129                 if (error == -EBUSY) {
1130                         ea_bdebug(bh, "already in cache");
1131                         error = 0;
1132                 }
1133         } else {
1134                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1135                 mb_cache_entry_release(ce);
1136         }
1137 }
1138
1139 /*
1140  * ext4_xattr_cmp()
1141  *
1142  * Compare two extended attribute blocks for equality.
1143  *
1144  * Returns 0 if the blocks are equal, 1 if they differ, and
1145  * a negative error number on errors.
1146  */
1147 static int
1148 ext4_xattr_cmp(struct ext4_xattr_header *header1,
1149                struct ext4_xattr_header *header2)
1150 {
1151         struct ext4_xattr_entry *entry1, *entry2;
1152
1153         entry1 = ENTRY(header1+1);
1154         entry2 = ENTRY(header2+1);
1155         while (!IS_LAST_ENTRY(entry1)) {
1156                 if (IS_LAST_ENTRY(entry2))
1157                         return 1;
1158                 if (entry1->e_hash != entry2->e_hash ||
1159                     entry1->e_name_index != entry2->e_name_index ||
1160                     entry1->e_name_len != entry2->e_name_len ||
1161                     entry1->e_value_size != entry2->e_value_size ||
1162                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1163                         return 1;
1164                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1165                         return -EIO;
1166                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1167                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1168                            le32_to_cpu(entry1->e_value_size)))
1169                         return 1;
1170
1171                 entry1 = EXT4_XATTR_NEXT(entry1);
1172                 entry2 = EXT4_XATTR_NEXT(entry2);
1173         }
1174         if (!IS_LAST_ENTRY(entry2))
1175                 return 1;
1176         return 0;
1177 }
1178
1179 /*
1180  * ext4_xattr_cache_find()
1181  *
1182  * Find an identical extended attribute block.
1183  *
1184  * Returns a pointer to the block found, or NULL if such a block was
1185  * not found or an error occurred.
1186  */
1187 static struct buffer_head *
1188 ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
1189                       struct mb_cache_entry **pce)
1190 {
1191         __u32 hash = le32_to_cpu(header->h_hash);
1192         struct mb_cache_entry *ce;
1193
1194         if (!header->h_hash)
1195                 return NULL;  /* never share */
1196         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1197 again:
1198         ce = mb_cache_entry_find_first(ext4_xattr_cache, 0,
1199                                        inode->i_sb->s_bdev, hash);
1200         while (ce) {
1201                 struct buffer_head *bh;
1202
1203                 if (IS_ERR(ce)) {
1204                         if (PTR_ERR(ce) == -EAGAIN)
1205                                 goto again;
1206                         break;
1207                 }
1208                 bh = sb_bread(inode->i_sb, ce->e_block);
1209                 if (!bh) {
1210                         ext4_error(inode->i_sb, __FUNCTION__,
1211                                 "inode %lu: block %lu read error",
1212                                 inode->i_ino, (unsigned long) ce->e_block);
1213                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1214                                 EXT4_XATTR_REFCOUNT_MAX) {
1215                         ea_idebug(inode, "block %lu refcount %d>=%d",
1216                                   (unsigned long) ce->e_block,
1217                                   le32_to_cpu(BHDR(bh)->h_refcount),
1218                                           EXT4_XATTR_REFCOUNT_MAX);
1219                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
1220                         *pce = ce;
1221                         return bh;
1222                 }
1223                 brelse(bh);
1224                 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
1225         }
1226         return NULL;
1227 }
1228
1229 #define NAME_HASH_SHIFT 5
1230 #define VALUE_HASH_SHIFT 16
1231
1232 /*
1233  * ext4_xattr_hash_entry()
1234  *
1235  * Compute the hash of an extended attribute.
1236  */
1237 static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
1238                                          struct ext4_xattr_entry *entry)
1239 {
1240         __u32 hash = 0;
1241         char *name = entry->e_name;
1242         int n;
1243
1244         for (n=0; n < entry->e_name_len; n++) {
1245                 hash = (hash << NAME_HASH_SHIFT) ^
1246                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1247                        *name++;
1248         }
1249
1250         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1251                 __le32 *value = (__le32 *)((char *)header +
1252                         le16_to_cpu(entry->e_value_offs));
1253                 for (n = (le32_to_cpu(entry->e_value_size) +
1254                      EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {
1255                         hash = (hash << VALUE_HASH_SHIFT) ^
1256                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1257                                le32_to_cpu(*value++);
1258                 }
1259         }
1260         entry->e_hash = cpu_to_le32(hash);
1261 }
1262
1263 #undef NAME_HASH_SHIFT
1264 #undef VALUE_HASH_SHIFT
1265
1266 #define BLOCK_HASH_SHIFT 16
1267
1268 /*
1269  * ext4_xattr_rehash()
1270  *
1271  * Re-compute the extended attribute hash value after an entry has changed.
1272  */
1273 static void ext4_xattr_rehash(struct ext4_xattr_header *header,
1274                               struct ext4_xattr_entry *entry)
1275 {
1276         struct ext4_xattr_entry *here;
1277         __u32 hash = 0;
1278
1279         ext4_xattr_hash_entry(header, entry);
1280         here = ENTRY(header+1);
1281         while (!IS_LAST_ENTRY(here)) {
1282                 if (!here->e_hash) {
1283                         /* Block is not shared if an entry's hash value == 0 */
1284                         hash = 0;
1285                         break;
1286                 }
1287                 hash = (hash << BLOCK_HASH_SHIFT) ^
1288                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1289                        le32_to_cpu(here->e_hash);
1290                 here = EXT4_XATTR_NEXT(here);
1291         }
1292         header->h_hash = cpu_to_le32(hash);
1293 }
1294
1295 #undef BLOCK_HASH_SHIFT
1296
1297 int __init
1298 init_ext4_xattr(void)
1299 {
1300         ext4_xattr_cache = mb_cache_create("ext4_xattr", NULL,
1301                 sizeof(struct mb_cache_entry) +
1302                 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1303         if (!ext4_xattr_cache)
1304                 return -ENOMEM;
1305         return 0;
1306 }
1307
1308 void
1309 exit_ext4_xattr(void)
1310 {
1311         if (ext4_xattr_cache)
1312                 mb_cache_destroy(ext4_xattr_cache);
1313         ext4_xattr_cache = NULL;
1314 }