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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         int error = 0;
 479
 480         ce = mb_cache_entry_get(ext4_xattr_cache, bh->b_bdev, bh->b_blocknr);
 481         error = ext4_journal_get_write_access(handle, bh);
 482         if (error)
 483                 goto out;
 484
 485         lock_buffer(bh);
 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                 ext4_free_blocks(handle, inode, bh->b_blocknr, 1);
 491                 get_bh(bh);
 492                 ext4_forget(handle, 1, inode, bh, bh->b_blocknr);
 493         } else {
 494                 BHDR(bh)->h_refcount = cpu_to_le32(
 495                                 le32_to_cpu(BHDR(bh)->h_refcount) - 1);
 496                 error = ext4_journal_dirty_metadata(handle, bh);
 497                 if (IS_SYNC(inode))
 498                         handle->h_sync = 1;
 499                 DQUOT_FREE_BLOCK(inode, 1);
 500                 ea_bdebug(bh, "refcount now=%d; releasing",
 501                           le32_to_cpu(BHDR(bh)->h_refcount));
 502                 if (ce)
 503                         mb_cache_entry_release(ce);
 504         }
 505         unlock_buffer(bh);
 506 out:
 507         ext4_std_error(inode->i_sb, error);
 508         return;
 509 }
 510
 511 struct ext4_xattr_info {
 512         int name_index;
 513         const char *name;
 514         const void *value;
 515         size_t value_len;
 516 };
 517
 518 struct ext4_xattr_search {
 519         struct ext4_xattr_entry *first;
 520         void *base;
 521         void *end;
 522         struct ext4_xattr_entry *here;
 523         int not_found;
 524 };
 525
 526 static int
 527 ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
 528 {
 529         struct ext4_xattr_entry *last;
 530         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
 531
 532         /* Compute min_offs and last. */
 533         last = s->first;
 534         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 535                 if (!last->e_value_block && last->e_value_size) {
 536                         size_t offs = le16_to_cpu(last->e_value_offs);
 537                         if (offs < min_offs)
 538                                 min_offs = offs;
 539                 }
 540         }
 541         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
 542         if (!s->not_found) {
 543                 if (!s->here->e_value_block && s->here->e_value_size) {
 544                         size_t size = le32_to_cpu(s->here->e_value_size);
 545                         free += EXT4_XATTR_SIZE(size);
 546                 }
 547                 free += EXT4_XATTR_LEN(name_len);
 548         }
 549         if (i->value) {
 550                 if (free < EXT4_XATTR_SIZE(i->value_len) ||
 551                     free < EXT4_XATTR_LEN(name_len) +
 552                            EXT4_XATTR_SIZE(i->value_len))
 553                         return -ENOSPC;
 554         }
 555
 556         if (i->value && s->not_found) {
 557                 /* Insert the new name. */
 558                 size_t size = EXT4_XATTR_LEN(name_len);
 559                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
 560                 memmove((void *)s->here + size, s->here, rest);
 561                 memset(s->here, 0, size);
 562                 s->here->e_name_index = i->name_index;
 563                 s->here->e_name_len = name_len;
 564                 memcpy(s->here->e_name, i->name, name_len);
 565         } else {
 566                 if (!s->here->e_value_block && s->here->e_value_size) {
 567                         void *first_val = s->base + min_offs;
 568                         size_t offs = le16_to_cpu(s->here->e_value_offs);
 569                         void *val = s->base + offs;
 570                         size_t size = EXT4_XATTR_SIZE(
 571                                 le32_to_cpu(s->here->e_value_size));
 572
 573                         if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
 574                                 /* The old and the new value have the same
 575                                    size. Just replace. */
 576                                 s->here->e_value_size =
 577                                         cpu_to_le32(i->value_len);
 578                                 memset(val + size - EXT4_XATTR_PAD, 0,
 579                                        EXT4_XATTR_PAD); /* Clear pad bytes. */
 580                                 memcpy(val, i->value, i->value_len);
 581                                 return 0;
 582                         }
 583
 584                         /* Remove the old value. */
 585                         memmove(first_val + size, first_val, val - first_val);
 586                         memset(first_val, 0, size);
 587                         s->here->e_value_size = 0;
 588                         s->here->e_value_offs = 0;
 589                         min_offs += size;
 590
 591                         /* Adjust all value offsets. */
 592                         last = s->first;
 593                         while (!IS_LAST_ENTRY(last)) {
 594                                 size_t o = le16_to_cpu(last->e_value_offs);
 595                                 if (!last->e_value_block &&
 596                                     last->e_value_size && o < offs)
 597                                         last->e_value_offs =
 598                                                 cpu_to_le16(o + size);
 599                                 last = EXT4_XATTR_NEXT(last);
 600                         }
 601                 }
 602                 if (!i->value) {
 603                         /* Remove the old name. */
 604                         size_t size = EXT4_XATTR_LEN(name_len);
 605                         last = ENTRY((void *)last - size);
 606                         memmove(s->here, (void *)s->here + size,
 607                                 (void *)last - (void *)s->here + sizeof(__u32));
 608                         memset(last, 0, size);
 609                 }
 610         }
 611
 612         if (i->value) {
 613                 /* Insert the new value. */
 614                 s->here->e_value_size = cpu_to_le32(i->value_len);
 615                 if (i->value_len) {
 616                         size_t size = EXT4_XATTR_SIZE(i->value_len);
 617                         void *val = s->base + min_offs - size;
 618                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
 619                         memset(val + size - EXT4_XATTR_PAD, 0,
 620                                EXT4_XATTR_PAD); /* Clear the pad bytes. */
 621                         memcpy(val, i->value, i->value_len);
 622                 }
 623         }
 624         return 0;
 625 }
 626
 627 struct ext4_xattr_block_find {
 628         struct ext4_xattr_search s;
 629         struct buffer_head *bh;
 630 };
 631
 632 static int
 633 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
 634                       struct ext4_xattr_block_find *bs)
 635 {
 636         struct super_block *sb = inode->i_sb;
 637         int error;
 638
 639         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
 640                   i->name_index, i->name, i->value, (long)i->value_len);
 641
 642         if (EXT4_I(inode)->i_file_acl) {
 643                 /* The inode already has an extended attribute block. */
 644                 bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);
 645                 error = -EIO;
 646                 if (!bs->bh)
 647                         goto cleanup;
 648                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
 649                         atomic_read(&(bs->bh->b_count)),
 650                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
 651                 if (ext4_xattr_check_block(bs->bh)) {
 652                         ext4_error(sb, __FUNCTION__,
 653                                 "inode %lu: bad block %llu", inode->i_ino,
 654                                 EXT4_I(inode)->i_file_acl);
 655                         error = -EIO;
 656                         goto cleanup;
 657                 }
 658                 /* Find the named attribute. */
 659                 bs->s.base = BHDR(bs->bh);
 660                 bs->s.first = BFIRST(bs->bh);
 661                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
 662                 bs->s.here = bs->s.first;
 663                 error = ext4_xattr_find_entry(&bs->s.here, i->name_index,
 664                                               i->name, bs->bh->b_size, 1);
 665                 if (error && error != -ENODATA)
 666                         goto cleanup;
 667                 bs->s.not_found = error;
 668         }
 669         error = 0;
 670
 671 cleanup:
 672         return error;
 673 }
 674
 675 static int
 676 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
 677                      struct ext4_xattr_info *i,
 678                      struct ext4_xattr_block_find *bs)
 679 {
 680         struct super_block *sb = inode->i_sb;
 681         struct buffer_head *new_bh = NULL;
 682         struct ext4_xattr_search *s = &bs->s;
 683         struct mb_cache_entry *ce = NULL;
 684         int error = 0;
 685
 686 #define header(x) ((struct ext4_xattr_header *)(x))
 687
 688         if (i->value && i->value_len > sb->s_blocksize)
 689                 return -ENOSPC;
 690         if (s->base) {
 691                 ce = mb_cache_entry_get(ext4_xattr_cache, bs->bh->b_bdev,
 692                                         bs->bh->b_blocknr);
 693                 error = ext4_journal_get_write_access(handle, bs->bh);
 694                 if (error)
 695                         goto cleanup;
 696                 lock_buffer(bs->bh);
 697
 698                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 699                         if (ce) {
 700                                 mb_cache_entry_free(ce);
 701                                 ce = NULL;
 702                         }
 703                         ea_bdebug(bs->bh, "modifying in-place");
 704                         error = ext4_xattr_set_entry(i, s);
 705                         if (!error) {
 706                                 if (!IS_LAST_ENTRY(s->first))
 707                                         ext4_xattr_rehash(header(s->base),
 708                                                           s->here);
 709                                 ext4_xattr_cache_insert(bs->bh);
 710                         }
 711                         unlock_buffer(bs->bh);
 712                         if (error == -EIO)
 713                                 goto bad_block;
 714                         if (!error)
 715                                 error = ext4_journal_dirty_metadata(handle,
 716                                                                     bs->bh);
 717                         if (error)
 718                                 goto cleanup;
 719                         goto inserted;
 720                 } else {
 721                         int offset = (char *)s->here - bs->bh->b_data;
 722
 723                         unlock_buffer(bs->bh);
 724                         jbd2_journal_release_buffer(handle, bs->bh);
 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_KERNEL);
 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 = kmalloc(sb->s_blocksize, GFP_KERNEL);
 743                 /* assert(header == s->base) */
 744                 error = -ENOMEM;
 745                 if (s->base == NULL)
 746                         goto cleanup;
 747                 memset(s->base, 0, sb->s_blocksize);
 748                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
 749                 header(s->base)->h_blocks = cpu_to_le32(1);
 750                 header(s->base)->h_refcount = cpu_to_le32(1);
 751                 s->first = ENTRY(header(s->base)+1);
 752                 s->here = ENTRY(header(s->base)+1);
 753                 s->end = s->base + sb->s_blocksize;
 754         }
 755
 756         error = ext4_xattr_set_entry(i, s);
 757         if (error == -EIO)
 758                 goto bad_block;
 759         if (error)
 760                 goto cleanup;
 761         if (!IS_LAST_ENTRY(s->first))
 762                 ext4_xattr_rehash(header(s->base), s->here);
 763
 764 inserted:
 765         if (!IS_LAST_ENTRY(s->first)) {
 766                 new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);
 767                 if (new_bh) {
 768                         /* We found an identical block in the cache. */
 769                         if (new_bh == bs->bh)
 770                                 ea_bdebug(new_bh, "keeping");
 771                         else {
 772                                 /* The old block is released after updating
 773                                    the inode. */
 774                                 error = -EDQUOT;
 775                                 if (DQUOT_ALLOC_BLOCK(inode, 1))
 776                                         goto cleanup;
 777                                 error = ext4_journal_get_write_access(handle,
 778                                                                       new_bh);
 779                                 if (error)
 780                                         goto cleanup_dquot;
 781                                 lock_buffer(new_bh);
 782                                 BHDR(new_bh)->h_refcount = cpu_to_le32(1 +
 783                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 784                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
 785                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 786                                 unlock_buffer(new_bh);
 787                                 error = ext4_journal_dirty_metadata(handle,
 788                                                                     new_bh);
 789                                 if (error)
 790                                         goto cleanup_dquot;
 791                         }
 792                         mb_cache_entry_release(ce);
 793                         ce = NULL;
 794                 } else if (bs->bh && s->base == bs->bh->b_data) {
 795                         /* We were modifying this block in-place. */
 796                         ea_bdebug(bs->bh, "keeping this block");
 797                         new_bh = bs->bh;
 798                         get_bh(new_bh);
 799                 } else {
 800                         /* We need to allocate a new block */
 801                         ext4_fsblk_t goal = le32_to_cpu(
 802                                         EXT4_SB(sb)->s_es->s_first_data_block) +
 803                                 (ext4_fsblk_t)EXT4_I(inode)->i_block_group *
 804                                 EXT4_BLOCKS_PER_GROUP(sb);
 805                         ext4_fsblk_t block = ext4_new_block(handle, inode,
 806                                                         goal, &error);
 807                         if (error)
 808                                 goto cleanup;
 809                         ea_idebug(inode, "creating block %d", block);
 810
 811                         new_bh = sb_getblk(sb, block);
 812                         if (!new_bh) {
 813 getblk_failed:
 814                                 ext4_free_blocks(handle, inode, block, 1);
 815                                 error = -EIO;
 816                                 goto cleanup;
 817                         }
 818                         lock_buffer(new_bh);
 819                         error = ext4_journal_get_create_access(handle, new_bh);
 820                         if (error) {
 821                                 unlock_buffer(new_bh);
 822                                 goto getblk_failed;
 823                         }
 824                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
 825                         set_buffer_uptodate(new_bh);
 826                         unlock_buffer(new_bh);
 827                         ext4_xattr_cache_insert(new_bh);
 828                         error = ext4_journal_dirty_metadata(handle, new_bh);
 829                         if (error)
 830                                 goto cleanup;
 831                 }
 832         }
 833
 834         /* Update the inode. */
 835         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
 836
 837         /* Drop the previous xattr block. */
 838         if (bs->bh && bs->bh != new_bh)
 839                 ext4_xattr_release_block(handle, inode, bs->bh);
 840         error = 0;
 841
 842 cleanup:
 843         if (ce)
 844                 mb_cache_entry_release(ce);
 845         brelse(new_bh);
 846         if (!(bs->bh && s->base == bs->bh->b_data))
 847                 kfree(s->base);
 848
 849         return error;
 850
 851 cleanup_dquot:
 852         DQUOT_FREE_BLOCK(inode, 1);
 853         goto cleanup;
 854
 855 bad_block:
 856         ext4_error(inode->i_sb, __FUNCTION__,
 857                    "inode %lu: bad block %llu", inode->i_ino,
 858                    EXT4_I(inode)->i_file_acl);
 859         goto cleanup;
 860
 861 #undef header
 862 }
 863
 864 struct ext4_xattr_ibody_find {
 865         struct ext4_xattr_search s;
 866         struct ext4_iloc iloc;
 867 };
 868
 869 static int
 870 ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
 871                       struct ext4_xattr_ibody_find *is)
 872 {
 873         struct ext4_xattr_ibody_header *header;
 874         struct ext4_inode *raw_inode;
 875         int error;
 876
 877         if (EXT4_I(inode)->i_extra_isize == 0)
 878                 return 0;
 879         raw_inode = ext4_raw_inode(&is->iloc);
 880         header = IHDR(inode, raw_inode);
 881         is->s.base = is->s.first = IFIRST(header);
 882         is->s.here = is->s.first;
 883         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 884         if (EXT4_I(inode)->i_state & EXT4_STATE_XATTR) {
 885                 error = ext4_xattr_check_names(IFIRST(header), is->s.end);
 886                 if (error)
 887                         return error;
 888                 /* Find the named attribute. */
 889                 error = ext4_xattr_find_entry(&is->s.here, i->name_index,
 890                                               i->name, is->s.end -
 891                                               (void *)is->s.base, 0);
 892                 if (error && error != -ENODATA)
 893                         return error;
 894                 is->s.not_found = error;
 895         }
 896         return 0;
 897 }
 898
 899 static int
 900 ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
 901                      struct ext4_xattr_info *i,
 902                      struct ext4_xattr_ibody_find *is)
 903 {
 904         struct ext4_xattr_ibody_header *header;
 905         struct ext4_xattr_search *s = &is->s;
 906         int error;
 907
 908         if (EXT4_I(inode)->i_extra_isize == 0)
 909                 return -ENOSPC;
 910         error = ext4_xattr_set_entry(i, s);
 911         if (error)
 912                 return error;
 913         header = IHDR(inode, ext4_raw_inode(&is->iloc));
 914         if (!IS_LAST_ENTRY(s->first)) {
 915                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
 916                 EXT4_I(inode)->i_state |= EXT4_STATE_XATTR;
 917         } else {
 918                 header->h_magic = cpu_to_le32(0);
 919                 EXT4_I(inode)->i_state &= ~EXT4_STATE_XATTR;
 920         }
 921         return 0;
 922 }
 923
 924 /*
 925  * ext4_xattr_set_handle()
 926  *
 927  * Create, replace or remove an extended attribute for this inode. Buffer
 928  * is NULL to remove an existing extended attribute, and non-NULL to
 929  * either replace an existing extended attribute, or create a new extended
 930  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 931  * specify that an extended attribute must exist and must not exist
 932  * previous to the call, respectively.
 933  *
 934  * Returns 0, or a negative error number on failure.
 935  */
 936 int
 937 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
 938                       const char *name, const void *value, size_t value_len,
 939                       int flags)
 940 {
 941         struct ext4_xattr_info i = {
 942                 .name_index = name_index,
 943                 .name = name,
 944                 .value = value,
 945                 .value_len = value_len,
 946
 947         };
 948         struct ext4_xattr_ibody_find is = {
 949                 .s = { .not_found = -ENODATA, },
 950         };
 951         struct ext4_xattr_block_find bs = {
 952                 .s = { .not_found = -ENODATA, },
 953         };
 954         int error;
 955
 956         if (!name)
 957                 return -EINVAL;
 958         if (strlen(name) > 255)
 959                 return -ERANGE;
 960         down_write(&EXT4_I(inode)->xattr_sem);
 961         error = ext4_get_inode_loc(inode, &is.iloc);
 962         if (error)
 963                 goto cleanup;
 964
 965         if (EXT4_I(inode)->i_state & EXT4_STATE_NEW) {
 966                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
 967                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
 968                 EXT4_I(inode)->i_state &= ~EXT4_STATE_NEW;
 969         }
 970
 971         error = ext4_xattr_ibody_find(inode, &i, &is);
 972         if (error)
 973                 goto cleanup;
 974         if (is.s.not_found)
 975                 error = ext4_xattr_block_find(inode, &i, &bs);
 976         if (error)
 977                 goto cleanup;
 978         if (is.s.not_found && bs.s.not_found) {
 979                 error = -ENODATA;
 980                 if (flags & XATTR_REPLACE)
 981                         goto cleanup;
 982                 error = 0;
 983                 if (!value)
 984                         goto cleanup;
 985         } else {
 986                 error = -EEXIST;
 987                 if (flags & XATTR_CREATE)
 988                         goto cleanup;
 989         }
 990         error = ext4_journal_get_write_access(handle, is.iloc.bh);
 991         if (error)
 992                 goto cleanup;
 993         if (!value) {
 994                 if (!is.s.not_found)
 995                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
 996                 else if (!bs.s.not_found)
 997                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
 998         } else {
 999                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1000                 if (!error && !bs.s.not_found) {
1001                         i.value = NULL;
1002                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1003                 } else if (error == -ENOSPC) {
1004                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1005                         if (error)
1006                                 goto cleanup;
1007                         if (!is.s.not_found) {
1008                                 i.value = NULL;
1009                                 error = ext4_xattr_ibody_set(handle, inode, &i,
1010                                                              &is);
1011                         }
1012                 }
1013         }
1014         if (!error) {
1015                 ext4_xattr_update_super_block(handle, inode->i_sb);
1016                 inode->i_ctime = CURRENT_TIME_SEC;
1017                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
1018                 /*
1019                  * The bh is consumed by ext4_mark_iloc_dirty, even with
1020                  * error != 0.
1021                  */
1022                 is.iloc.bh = NULL;
1023                 if (IS_SYNC(inode))
1024                         handle->h_sync = 1;
1025         }
1026
1027 cleanup:
1028         brelse(is.iloc.bh);
1029         brelse(bs.bh);
1030         up_write(&EXT4_I(inode)->xattr_sem);
1031         return error;
1032 }
1033
1034 /*
1035  * ext4_xattr_set()
1036  *
1037  * Like ext4_xattr_set_handle, but start from an inode. This extended
1038  * attribute modification is a filesystem transaction by itself.
1039  *
1040  * Returns 0, or a negative error number on failure.
1041  */
1042 int
1043 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
1044                const void *value, size_t value_len, int flags)
1045 {
1046         handle_t *handle;
1047         int error, retries = 0;
1048
1049 retry:
1050         handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
1051         if (IS_ERR(handle)) {
1052                 error = PTR_ERR(handle);
1053         } else {
1054                 int error2;
1055
1056                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
1057                                               value, value_len, flags);
1058                 error2 = ext4_journal_stop(handle);
1059                 if (error == -ENOSPC &&
1060                     ext4_should_retry_alloc(inode->i_sb, &retries))
1061                         goto retry;
1062                 if (error == 0)
1063                         error = error2;
1064         }
1065
1066         return error;
1067 }
1068
1069 /*
1070  * ext4_xattr_delete_inode()
1071  *
1072  * Free extended attribute resources associated with this inode. This
1073  * is called immediately before an inode is freed. We have exclusive
1074  * access to the inode.
1075  */
1076 void
1077 ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)
1078 {
1079         struct buffer_head *bh = NULL;
1080
1081         if (!EXT4_I(inode)->i_file_acl)
1082                 goto cleanup;
1083         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1084         if (!bh) {
1085                 ext4_error(inode->i_sb, __FUNCTION__,
1086                         "inode %lu: block %llu read error", inode->i_ino,
1087                         EXT4_I(inode)->i_file_acl);
1088                 goto cleanup;
1089         }
1090         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
1091             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1092                 ext4_error(inode->i_sb, __FUNCTION__,
1093                         "inode %lu: bad block %llu", inode->i_ino,
1094                         EXT4_I(inode)->i_file_acl);
1095                 goto cleanup;
1096         }
1097         ext4_xattr_release_block(handle, inode, bh);
1098         EXT4_I(inode)->i_file_acl = 0;
1099
1100 cleanup:
1101         brelse(bh);
1102 }
1103
1104 /*
1105  * ext4_xattr_put_super()
1106  *
1107  * This is called when a file system is unmounted.
1108  */
1109 void
1110 ext4_xattr_put_super(struct super_block *sb)
1111 {
1112         mb_cache_shrink(sb->s_bdev);
1113 }
1114
1115 /*
1116  * ext4_xattr_cache_insert()
1117  *
1118  * Create a new entry in the extended attribute cache, and insert
1119  * it unless such an entry is already in the cache.
1120  *
1121  * Returns 0, or a negative error number on failure.
1122  */
1123 static void
1124 ext4_xattr_cache_insert(struct buffer_head *bh)
1125 {
1126         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1127         struct mb_cache_entry *ce;
1128         int error;
1129
1130         ce = mb_cache_entry_alloc(ext4_xattr_cache);
1131         if (!ce) {
1132                 ea_bdebug(bh, "out of memory");
1133                 return;
1134         }
1135         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
1136         if (error) {
1137                 mb_cache_entry_free(ce);
1138                 if (error == -EBUSY) {
1139                         ea_bdebug(bh, "already in cache");
1140                         error = 0;
1141                 }
1142         } else {
1143                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1144                 mb_cache_entry_release(ce);
1145         }
1146 }
1147
1148 /*
1149  * ext4_xattr_cmp()
1150  *
1151  * Compare two extended attribute blocks for equality.
1152  *
1153  * Returns 0 if the blocks are equal, 1 if they differ, and
1154  * a negative error number on errors.
1155  */
1156 static int
1157 ext4_xattr_cmp(struct ext4_xattr_header *header1,
1158                struct ext4_xattr_header *header2)
1159 {
1160         struct ext4_xattr_entry *entry1, *entry2;
1161
1162         entry1 = ENTRY(header1+1);
1163         entry2 = ENTRY(header2+1);
1164         while (!IS_LAST_ENTRY(entry1)) {
1165                 if (IS_LAST_ENTRY(entry2))
1166                         return 1;
1167                 if (entry1->e_hash != entry2->e_hash ||
1168                     entry1->e_name_index != entry2->e_name_index ||
1169                     entry1->e_name_len != entry2->e_name_len ||
1170                     entry1->e_value_size != entry2->e_value_size ||
1171                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1172                         return 1;
1173                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1174                         return -EIO;
1175                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1176                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1177                            le32_to_cpu(entry1->e_value_size)))
1178                         return 1;
1179
1180                 entry1 = EXT4_XATTR_NEXT(entry1);
1181                 entry2 = EXT4_XATTR_NEXT(entry2);
1182         }
1183         if (!IS_LAST_ENTRY(entry2))
1184                 return 1;
1185         return 0;
1186 }
1187
1188 /*
1189  * ext4_xattr_cache_find()
1190  *
1191  * Find an identical extended attribute block.
1192  *
1193  * Returns a pointer to the block found, or NULL if such a block was
1194  * not found or an error occurred.
1195  */
1196 static struct buffer_head *
1197 ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
1198                       struct mb_cache_entry **pce)
1199 {
1200         __u32 hash = le32_to_cpu(header->h_hash);
1201         struct mb_cache_entry *ce;
1202
1203         if (!header->h_hash)
1204                 return NULL;  /* never share */
1205         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1206 again:
1207         ce = mb_cache_entry_find_first(ext4_xattr_cache, 0,
1208                                        inode->i_sb->s_bdev, hash);
1209         while (ce) {
1210                 struct buffer_head *bh;
1211
1212                 if (IS_ERR(ce)) {
1213                         if (PTR_ERR(ce) == -EAGAIN)
1214                                 goto again;
1215                         break;
1216                 }
1217                 bh = sb_bread(inode->i_sb, ce->e_block);
1218                 if (!bh) {
1219                         ext4_error(inode->i_sb, __FUNCTION__,
1220                                 "inode %lu: block %lu read error",
1221                                 inode->i_ino, (unsigned long) ce->e_block);
1222                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1223                                 EXT4_XATTR_REFCOUNT_MAX) {
1224                         ea_idebug(inode, "block %lu refcount %d>=%d",
1225                                   (unsigned long) ce->e_block,
1226                                   le32_to_cpu(BHDR(bh)->h_refcount),
1227                                           EXT4_XATTR_REFCOUNT_MAX);
1228                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
1229                         *pce = ce;
1230                         return bh;
1231                 }
1232                 brelse(bh);
1233                 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
1234         }
1235         return NULL;
1236 }
1237
1238 #define NAME_HASH_SHIFT 5
1239 #define VALUE_HASH_SHIFT 16
1240
1241 /*
1242  * ext4_xattr_hash_entry()
1243  *
1244  * Compute the hash of an extended attribute.
1245  */
1246 static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
1247                                          struct ext4_xattr_entry *entry)
1248 {
1249         __u32 hash = 0;
1250         char *name = entry->e_name;
1251         int n;
1252
1253         for (n=0; n < entry->e_name_len; n++) {
1254                 hash = (hash << NAME_HASH_SHIFT) ^
1255                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1256                        *name++;
1257         }
1258
1259         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1260                 __le32 *value = (__le32 *)((char *)header +
1261                         le16_to_cpu(entry->e_value_offs));
1262                 for (n = (le32_to_cpu(entry->e_value_size) +
1263                      EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {
1264                         hash = (hash << VALUE_HASH_SHIFT) ^
1265                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1266                                le32_to_cpu(*value++);
1267                 }
1268         }
1269         entry->e_hash = cpu_to_le32(hash);
1270 }
1271
1272 #undef NAME_HASH_SHIFT
1273 #undef VALUE_HASH_SHIFT
1274
1275 #define BLOCK_HASH_SHIFT 16
1276
1277 /*
1278  * ext4_xattr_rehash()
1279  *
1280  * Re-compute the extended attribute hash value after an entry has changed.
1281  */
1282 static void ext4_xattr_rehash(struct ext4_xattr_header *header,
1283                               struct ext4_xattr_entry *entry)
1284 {
1285         struct ext4_xattr_entry *here;
1286         __u32 hash = 0;
1287
1288         ext4_xattr_hash_entry(header, entry);
1289         here = ENTRY(header+1);
1290         while (!IS_LAST_ENTRY(here)) {
1291                 if (!here->e_hash) {
1292                         /* Block is not shared if an entry's hash value == 0 */
1293                         hash = 0;
1294                         break;
1295                 }
1296                 hash = (hash << BLOCK_HASH_SHIFT) ^
1297                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1298                        le32_to_cpu(here->e_hash);
1299                 here = EXT4_XATTR_NEXT(here);
1300         }
1301         header->h_hash = cpu_to_le32(hash);
1302 }
1303
1304 #undef BLOCK_HASH_SHIFT
1305
1306 int __init
1307 init_ext4_xattr(void)
1308 {
1309         ext4_xattr_cache = mb_cache_create("ext4_xattr", NULL,
1310                 sizeof(struct mb_cache_entry) +
1311                 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1312         if (!ext4_xattr_cache)
1313                 return -ENOMEM;
1314         return 0;
1315 }
1316
1317 void
1318 exit_ext4_xattr(void)
1319 {
1320         if (ext4_xattr_cache)
1321                 mb_cache_destroy(ext4_xattr_cache);
1322         ext4_xattr_cache = NULL;
1323 }