fs/ext4/xattr.c

   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 <linux/vs_dlimit.h>
  62 #include "xattr.h"
  63 #include "acl.h"
  64
  65 #define BHDR(bh) ((struct ext4_xattr_header *)((bh)->b_data))
  66 #define ENTRY(ptr) ((struct ext4_xattr_entry *)(ptr))
  67 #define BFIRST(bh) ENTRY(BHDR(bh)+1)
  68 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
  69
  70 #define IHDR(inode, raw_inode) \
  71         ((struct ext4_xattr_ibody_header *) \
  72                 ((void *)raw_inode + \
  73                  EXT4_GOOD_OLD_INODE_SIZE + \
  74                  EXT4_I(inode)->i_extra_isize))
  75 #define IFIRST(hdr) ((struct ext4_xattr_entry *)((hdr)+1))
  76
  77 #ifdef EXT4_XATTR_DEBUG
  78 # define ea_idebug(inode, f...) do { \
  79                 printk(KERN_DEBUG "inode %s:%lu: ", \
  80                         inode->i_sb->s_id, inode->i_ino); \
  81                 printk(f); \
  82                 printk("\n"); \
  83         } while (0)
  84 # define ea_bdebug(bh, f...) do { \
  85                 char b[BDEVNAME_SIZE]; \
  86                 printk(KERN_DEBUG "block %s:%lu: ", \
  87                         bdevname(bh->b_bdev, b), \
  88                         (unsigned long) bh->b_blocknr); \
  89                 printk(f); \
  90                 printk("\n"); \
  91         } while (0)
  92 #else
  93 # define ea_idebug(f...)
  94 # define ea_bdebug(f...)
  95 #endif
  96
  97 static void ext4_xattr_cache_insert(struct buffer_head *);
  98 static struct buffer_head *ext4_xattr_cache_find(struct inode *,
  99                                                  struct ext4_xattr_header *,
 100                                                  struct mb_cache_entry **);
 101 static void ext4_xattr_rehash(struct ext4_xattr_header *,
 102                               struct ext4_xattr_entry *);
 103
 104 static struct mb_cache *ext4_xattr_cache;
 105
 106 static struct xattr_handler *ext4_xattr_handler_map[] = {
 107         [EXT4_XATTR_INDEX_USER]              = &ext4_xattr_user_handler,
 108 #ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
 109         [EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &ext4_xattr_acl_access_handler,
 110         [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext4_xattr_acl_default_handler,
 111 #endif
 112         [EXT4_XATTR_INDEX_TRUSTED]           = &ext4_xattr_trusted_handler,
 113 #ifdef CONFIG_EXT4DEV_FS_SECURITY
 114         [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
 115 #endif
 116 };
 117
 118 struct xattr_handler *ext4_xattr_handlers[] = {
 119         &ext4_xattr_user_handler,
 120         &ext4_xattr_trusted_handler,
 121 #ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
 122         &ext4_xattr_acl_access_handler,
 123         &ext4_xattr_acl_default_handler,
 124 #endif
 125 #ifdef CONFIG_EXT4DEV_FS_SECURITY
 126         &ext4_xattr_security_handler,
 127 #endif
 128         NULL
 129 };
 130
 131 static inline struct xattr_handler *
 132 ext4_xattr_handler(int name_index)
 133 {
 134         struct xattr_handler *handler = NULL;
 135
 136         if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
 137                 handler = ext4_xattr_handler_map[name_index];
 138         return handler;
 139 }
 140
 141 /*
 142  * Inode operation listxattr()
 143  *
 144  * dentry->d_inode->i_mutex: don't care
 145  */
 146 ssize_t
 147 ext4_listxattr(struct dentry *dentry, char *buffer, size_t size)
 148 {
 149         return ext4_xattr_list(dentry->d_inode, buffer, size);
 150 }
 151
 152 static int
 153 ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end)
 154 {
 155         while (!IS_LAST_ENTRY(entry)) {
 156                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(entry);
 157                 if ((void *)next >= end)
 158                         return -EIO;
 159                 entry = next;
 160         }
 161         return 0;
 162 }
 163
 164 static inline int
 165 ext4_xattr_check_block(struct buffer_head *bh)
 166 {
 167         int error;
 168
 169         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
 170             BHDR(bh)->h_blocks != cpu_to_le32(1))
 171                 return -EIO;
 172         error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
 173         return error;
 174 }
 175
 176 static inline int
 177 ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size)
 178 {
 179         size_t value_size = le32_to_cpu(entry->e_value_size);
 180
 181         if (entry->e_value_block != 0 || value_size > size ||
 182             le16_to_cpu(entry->e_value_offs) + value_size > size)
 183                 return -EIO;
 184         return 0;
 185 }
 186
 187 static int
 188 ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
 189                       const char *name, size_t size, int sorted)
 190 {
 191         struct ext4_xattr_entry *entry;
 192         size_t name_len;
 193         int cmp = 1;
 194
 195         if (name == NULL)
 196                 return -EINVAL;
 197         name_len = strlen(name);
 198         entry = *pentry;
 199         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 200                 cmp = name_index - entry->e_name_index;
 201                 if (!cmp)
 202                         cmp = name_len - entry->e_name_len;
 203                 if (!cmp)
 204                         cmp = memcmp(name, entry->e_name, name_len);
 205                 if (cmp <= 0 && (sorted || cmp == 0))
 206                         break;
 207         }
 208         *pentry = entry;
 209         if (!cmp && ext4_xattr_check_entry(entry, size))
 210                         return -EIO;
 211         return cmp ? -ENODATA : 0;
 212 }
 213
 214 static int
 215 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
 216                      void *buffer, size_t buffer_size)
 217 {
 218         struct buffer_head *bh = NULL;
 219         struct ext4_xattr_entry *entry;
 220         size_t size;
 221         int error;
 222
 223         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 224                   name_index, name, buffer, (long)buffer_size);
 225
 226         error = -ENODATA;
 227         if (!EXT4_I(inode)->i_file_acl)
 228                 goto cleanup;
 229         ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl);
 230         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 231         if (!bh)
 232                 goto cleanup;
 233         ea_bdebug(bh, "b_count=%d, refcount=%d",
 234                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 235         if (ext4_xattr_check_block(bh)) {
 236 bad_block:      ext4_error(inode->i_sb, __FUNCTION__,
 237                            "inode %lu: bad block %llu", inode->i_ino,
 238                            EXT4_I(inode)->i_file_acl);
 239                 error = -EIO;
 240                 goto cleanup;
 241         }
 242         ext4_xattr_cache_insert(bh);
 243         entry = BFIRST(bh);
 244         error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
 245         if (error == -EIO)
 246                 goto bad_block;
 247         if (error)
 248                 goto cleanup;
 249         size = le32_to_cpu(entry->e_value_size);
 250         if (buffer) {
 251                 error = -ERANGE;
 252                 if (size > buffer_size)
 253                         goto cleanup;
 254                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
 255                        size);
 256         }
 257         error = size;
 258
 259 cleanup:
 260         brelse(bh);
 261         return error;
 262 }
 263
 264 static int
 265 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 266                      void *buffer, size_t buffer_size)
 267 {
 268         struct ext4_xattr_ibody_header *header;
 269         struct ext4_xattr_entry *entry;
 270         struct ext4_inode *raw_inode;
 271         struct ext4_iloc iloc;
 272         size_t size;
 273         void *end;
 274         int error;
 275
 276         if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR))
 277                 return -ENODATA;
 278         error = ext4_get_inode_loc(inode, &iloc);
 279         if (error)
 280                 return error;
 281         raw_inode = ext4_raw_inode(&iloc);
 282         header = IHDR(inode, raw_inode);
 283         entry = IFIRST(header);
 284         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 285         error = ext4_xattr_check_names(entry, end);
 286         if (error)
 287                 goto cleanup;
 288         error = ext4_xattr_find_entry(&entry, name_index, name,
 289                                       end - (void *)entry, 0);
 290         if (error)
 291                 goto cleanup;
 292         size = le32_to_cpu(entry->e_value_size);
 293         if (buffer) {
 294                 error = -ERANGE;
 295                 if (size > buffer_size)
 296                         goto cleanup;
 297                 memcpy(buffer, (void *)IFIRST(header) +
 298                        le16_to_cpu(entry->e_value_offs), size);
 299         }
 300         error = size;
 301
 302 cleanup:
 303         brelse(iloc.bh);
 304         return error;
 305 }
 306
 307 /*
 308  * ext4_xattr_get()
 309  *
 310  * Copy an extended attribute into the buffer
 311  * provided, or compute the buffer size required.
 312  * Buffer is NULL to compute the size of the buffer required.
 313  *
 314  * Returns a negative error number on failure, or the number of bytes
 315  * used / required on success.
 316  */
 317 int
 318 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
 319                void *buffer, size_t buffer_size)
 320 {
 321         int error;
 322
 323         down_read(&EXT4_I(inode)->xattr_sem);
 324         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
 325                                      buffer_size);
 326         if (error == -ENODATA)
 327                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
 328                                              buffer_size);
 329         up_read(&EXT4_I(inode)->xattr_sem);
 330         return error;
 331 }
 332
 333 static int
 334 ext4_xattr_list_entries(struct inode *inode, struct ext4_xattr_entry *entry,
 335                         char *buffer, size_t buffer_size)
 336 {
 337         size_t rest = buffer_size;
 338
 339         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 340                 struct xattr_handler *handler =
 341                         ext4_xattr_handler(entry->e_name_index);
 342
 343                 if (handler) {
 344                         size_t size = handler->list(inode, buffer, rest,
 345                                                     entry->e_name,
 346                                                     entry->e_name_len);
 347                         if (buffer) {
 348                                 if (size > rest)
 349                                         return -ERANGE;
 350                                 buffer += size;
 351                         }
 352                         rest -= size;
 353                 }
 354         }
 355         return buffer_size - rest;
 356 }
 357
 358 static int
 359 ext4_xattr_block_list(struct inode *inode, char *buffer, size_t buffer_size)
 360 {
 361         struct buffer_head *bh = NULL;
 362         int error;
 363
 364         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 365                   buffer, (long)buffer_size);
 366
 367         error = 0;
 368         if (!EXT4_I(inode)->i_file_acl)
 369                 goto cleanup;
 370         ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl);
 371         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 372         error = -EIO;
 373         if (!bh)
 374                 goto cleanup;
 375         ea_bdebug(bh, "b_count=%d, refcount=%d",
 376                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 377         if (ext4_xattr_check_block(bh)) {
 378                 ext4_error(inode->i_sb, __FUNCTION__,
 379                            "inode %lu: bad block %llu", inode->i_ino,
 380                            EXT4_I(inode)->i_file_acl);
 381                 error = -EIO;
 382                 goto cleanup;
 383         }
 384         ext4_xattr_cache_insert(bh);
 385         error = ext4_xattr_list_entries(inode, BFIRST(bh), buffer, buffer_size);
 386
 387 cleanup:
 388         brelse(bh);
 389
 390         return error;
 391 }
 392
 393 static int
 394 ext4_xattr_ibody_list(struct inode *inode, char *buffer, size_t buffer_size)
 395 {
 396         struct ext4_xattr_ibody_header *header;
 397         struct ext4_inode *raw_inode;
 398         struct ext4_iloc iloc;
 399         void *end;
 400         int error;
 401
 402         if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR))
 403                 return 0;
 404         error = ext4_get_inode_loc(inode, &iloc);
 405         if (error)
 406                 return error;
 407         raw_inode = ext4_raw_inode(&iloc);
 408         header = IHDR(inode, raw_inode);
 409         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 410         error = ext4_xattr_check_names(IFIRST(header), end);
 411         if (error)
 412                 goto cleanup;
 413         error = ext4_xattr_list_entries(inode, IFIRST(header),
 414                                         buffer, buffer_size);
 415
 416 cleanup:
 417         brelse(iloc.bh);
 418         return error;
 419 }
 420
 421 /*
 422  * ext4_xattr_list()
 423  *
 424  * Copy a list of attribute names into the buffer
 425  * provided, or compute the buffer size required.
 426  * Buffer is NULL to compute the size of the buffer required.
 427  *
 428  * Returns a negative error number on failure, or the number of bytes
 429  * used / required on success.
 430  */
 431 int
 432 ext4_xattr_list(struct inode *inode, char *buffer, size_t buffer_size)
 433 {
 434         int i_error, b_error;
 435
 436         down_read(&EXT4_I(inode)->xattr_sem);
 437         i_error = ext4_xattr_ibody_list(inode, buffer, buffer_size);
 438         if (i_error < 0) {
 439                 b_error = 0;
 440         } else {
 441                 if (buffer) {
 442                         buffer += i_error;
 443                         buffer_size -= i_error;
 444                 }
 445                 b_error = ext4_xattr_block_list(inode, buffer, buffer_size);
 446                 if (b_error < 0)
 447                         i_error = 0;
 448         }
 449         up_read(&EXT4_I(inode)->xattr_sem);
 450         return i_error + b_error;
 451 }
 452
 453 /*
 454  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 455  * not set, set it.
 456  */
 457 static void ext4_xattr_update_super_block(handle_t *handle,
 458                                           struct super_block *sb)
 459 {
 460         if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR))
 461                 return;
 462
 463         if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
 464                 EXT4_SET_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR);
 465                 sb->s_dirt = 1;
 466                 ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh);
 467         }
 468 }
 469
 470 /*
 471  * Release the xattr block BH: If the reference count is > 1, decrement
 472  * it; otherwise free the block.
 473  */
 474 static void
 475 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
 476                          struct buffer_head *bh)
 477 {
 478         struct mb_cache_entry *ce = NULL;
 479
 480         ce = mb_cache_entry_get(ext4_xattr_cache, bh->b_bdev, bh->b_blocknr);
 481         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
 482                 ea_bdebug(bh, "refcount now=0; freeing");
 483                 if (ce)
 484                         mb_cache_entry_free(ce);
 485                 ext4_free_blocks(handle, inode, bh->b_blocknr, 1);
 486                 get_bh(bh);
 487                 ext4_forget(handle, 1, inode, bh, bh->b_blocknr);
 488         } else {
 489                 if (ext4_journal_get_write_access(handle, bh) == 0) {
 490                         lock_buffer(bh);
 491                         BHDR(bh)->h_refcount = cpu_to_le32(
 492                                 le32_to_cpu(BHDR(bh)->h_refcount) - 1);
 493                         ext4_journal_dirty_metadata(handle, bh);
 494                         if (IS_SYNC(inode))
 495                                 handle->h_sync = 1;
 496                         DLIMIT_FREE_BLOCK(inode, 1);
 497                         DQUOT_FREE_BLOCK(inode, 1);
 498                         unlock_buffer(bh);
 499                         ea_bdebug(bh, "refcount now=%d; releasing",
 500                                   le32_to_cpu(BHDR(bh)->h_refcount));
 501                 }
 502                 if (ce)
 503                         mb_cache_entry_release(ce);
 504         }
 505 }
 506
 507 struct ext4_xattr_info {
 508         int name_index;
 509         const char *name;
 510         const void *value;
 511         size_t value_len;
 512 };
 513
 514 struct ext4_xattr_search {
 515         struct ext4_xattr_entry *first;
 516         void *base;
 517         void *end;
 518         struct ext4_xattr_entry *here;
 519         int not_found;
 520 };
 521
 522 static int
 523 ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
 524 {
 525         struct ext4_xattr_entry *last;
 526         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
 527
 528         /* Compute min_offs and last. */
 529         last = s->first;
 530         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 531                 if (!last->e_value_block && last->e_value_size) {
 532                         size_t offs = le16_to_cpu(last->e_value_offs);
 533                         if (offs < min_offs)
 534                                 min_offs = offs;
 535                 }
 536         }
 537         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
 538         if (!s->not_found) {
 539                 if (!s->here->e_value_block && s->here->e_value_size) {
 540                         size_t size = le32_to_cpu(s->here->e_value_size);
 541                         free += EXT4_XATTR_SIZE(size);
 542                 }
 543                 free += EXT4_XATTR_LEN(name_len);
 544         }
 545         if (i->value) {
 546                 if (free < EXT4_XATTR_SIZE(i->value_len) ||
 547                     free < EXT4_XATTR_LEN(name_len) +
 548                            EXT4_XATTR_SIZE(i->value_len))
 549                         return -ENOSPC;
 550         }
 551
 552         if (i->value && s->not_found) {
 553                 /* Insert the new name. */
 554                 size_t size = EXT4_XATTR_LEN(name_len);
 555                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
 556                 memmove((void *)s->here + size, s->here, rest);
 557                 memset(s->here, 0, size);
 558                 s->here->e_name_index = i->name_index;
 559                 s->here->e_name_len = name_len;
 560                 memcpy(s->here->e_name, i->name, name_len);
 561         } else {
 562                 if (!s->here->e_value_block && s->here->e_value_size) {
 563                         void *first_val = s->base + min_offs;
 564                         size_t offs = le16_to_cpu(s->here->e_value_offs);
 565                         void *val = s->base + offs;
 566                         size_t size = EXT4_XATTR_SIZE(
 567                                 le32_to_cpu(s->here->e_value_size));
 568
 569                         if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
 570                                 /* The old and the new value have the same
 571                                    size. Just replace. */
 572                                 s->here->e_value_size =
 573                                         cpu_to_le32(i->value_len);
 574                                 memset(val + size - EXT4_XATTR_PAD, 0,
 575                                        EXT4_XATTR_PAD); /* Clear pad bytes. */
 576                                 memcpy(val, i->value, i->value_len);
 577                                 return 0;
 578                         }
 579
 580                         /* Remove the old value. */
 581                         memmove(first_val + size, first_val, val - first_val);
 582                         memset(first_val, 0, size);
 583                         s->here->e_value_size = 0;
 584                         s->here->e_value_offs = 0;
 585                         min_offs += size;
 586
 587                         /* Adjust all value offsets. */
 588                         last = s->first;
 589                         while (!IS_LAST_ENTRY(last)) {
 590                                 size_t o = le16_to_cpu(last->e_value_offs);
 591                                 if (!last->e_value_block &&
 592                                     last->e_value_size && o < offs)
 593                                         last->e_value_offs =
 594                                                 cpu_to_le16(o + size);
 595                                 last = EXT4_XATTR_NEXT(last);
 596                         }
 597                 }
 598                 if (!i->value) {
 599                         /* Remove the old name. */
 600                         size_t size = EXT4_XATTR_LEN(name_len);
 601                         last = ENTRY((void *)last - size);
 602                         memmove(s->here, (void *)s->here + size,
 603                                 (void *)last - (void *)s->here + sizeof(__u32));
 604                         memset(last, 0, size);
 605                 }
 606         }
 607
 608         if (i->value) {
 609                 /* Insert the new value. */
 610                 s->here->e_value_size = cpu_to_le32(i->value_len);
 611                 if (i->value_len) {
 612                         size_t size = EXT4_XATTR_SIZE(i->value_len);
 613                         void *val = s->base + min_offs - size;
 614                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
 615                         memset(val + size - EXT4_XATTR_PAD, 0,
 616                                EXT4_XATTR_PAD); /* Clear the pad bytes. */
 617                         memcpy(val, i->value, i->value_len);
 618                 }
 619         }
 620         return 0;
 621 }
 622
 623 struct ext4_xattr_block_find {
 624         struct ext4_xattr_search s;
 625         struct buffer_head *bh;
 626 };
 627
 628 static int
 629 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
 630                       struct ext4_xattr_block_find *bs)
 631 {
 632         struct super_block *sb = inode->i_sb;
 633         int error;
 634
 635         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
 636                   i->name_index, i->name, i->value, (long)i->value_len);
 637
 638         if (EXT4_I(inode)->i_file_acl) {
 639                 /* The inode already has an extended attribute block. */
 640                 bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);
 641                 error = -EIO;
 642                 if (!bs->bh)
 643                         goto cleanup;
 644                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
 645                         atomic_read(&(bs->bh->b_count)),
 646                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
 647                 if (ext4_xattr_check_block(bs->bh)) {
 648                         ext4_error(sb, __FUNCTION__,
 649                                 "inode %lu: bad block %llu", inode->i_ino,
 650                                 EXT4_I(inode)->i_file_acl);
 651                         error = -EIO;
 652                         goto cleanup;
 653                 }
 654                 /* Find the named attribute. */
 655                 bs->s.base = BHDR(bs->bh);
 656                 bs->s.first = BFIRST(bs->bh);
 657                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
 658                 bs->s.here = bs->s.first;
 659                 error = ext4_xattr_find_entry(&bs->s.here, i->name_index,
 660                                               i->name, bs->bh->b_size, 1);
 661                 if (error && error != -ENODATA)
 662                         goto cleanup;
 663                 bs->s.not_found = error;
 664         }
 665         error = 0;
 666
 667 cleanup:
 668         return error;
 669 }
 670
 671 static int
 672 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
 673                      struct ext4_xattr_info *i,
 674                      struct ext4_xattr_block_find *bs)
 675 {
 676         struct super_block *sb = inode->i_sb;
 677         struct buffer_head *new_bh = NULL;
 678         struct ext4_xattr_search *s = &bs->s;
 679         struct mb_cache_entry *ce = NULL;
 680         int error;
 681
 682 #define header(x) ((struct ext4_xattr_header *)(x))
 683
 684         if (i->value && i->value_len > sb->s_blocksize)
 685                 return -ENOSPC;
 686         if (s->base) {
 687                 ce = mb_cache_entry_get(ext4_xattr_cache, bs->bh->b_bdev,
 688                                         bs->bh->b_blocknr);
 689                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 690                         if (ce) {
 691                                 mb_cache_entry_free(ce);
 692                                 ce = NULL;
 693                         }
 694                         ea_bdebug(bs->bh, "modifying in-place");
 695                         error = ext4_journal_get_write_access(handle, bs->bh);
 696                         if (error)
 697                                 goto cleanup;
 698                         lock_buffer(bs->bh);
 699                         error = ext4_xattr_set_entry(i, s);
 700                         if (!error) {
 701                                 if (!IS_LAST_ENTRY(s->first))
 702                                         ext4_xattr_rehash(header(s->base),
 703                                                           s->here);
 704                                 ext4_xattr_cache_insert(bs->bh);
 705                         }
 706                         unlock_buffer(bs->bh);
 707                         if (error == -EIO)
 708                                 goto bad_block;
 709                         if (!error)
 710                                 error = ext4_journal_dirty_metadata(handle,
 711                                                                     bs->bh);
 712                         if (error)
 713                                 goto cleanup;
 714                         goto inserted;
 715                 } else {
 716                         int offset = (char *)s->here - bs->bh->b_data;
 717
 718                         if (ce) {
 719                                 mb_cache_entry_release(ce);
 720                                 ce = NULL;
 721                         }
 722                         ea_bdebug(bs->bh, "cloning");
 723                         s->base = kmalloc(bs->bh->b_size, GFP_KERNEL);
 724                         error = -ENOMEM;
 725                         if (s->base == NULL)
 726                                 goto cleanup;
 727                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 728                         s->first = ENTRY(header(s->base)+1);
 729                         header(s->base)->h_refcount = cpu_to_le32(1);
 730                         s->here = ENTRY(s->base + offset);
 731                         s->end = s->base + bs->bh->b_size;
 732                 }
 733         } else {
 734                 /* Allocate a buffer where we construct the new block. */
 735                 s->base = kmalloc(sb->s_blocksize, GFP_KERNEL);
 736                 /* assert(header == s->base) */
 737                 error = -ENOMEM;
 738                 if (s->base == NULL)
 739                         goto cleanup;
 740                 memset(s->base, 0, sb->s_blocksize);
 741                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
 742                 header(s->base)->h_blocks = cpu_to_le32(1);
 743                 header(s->base)->h_refcount = cpu_to_le32(1);
 744                 s->first = ENTRY(header(s->base)+1);
 745                 s->here = ENTRY(header(s->base)+1);
 746                 s->end = s->base + sb->s_blocksize;
 747         }
 748
 749         error = ext4_xattr_set_entry(i, s);
 750         if (error == -EIO)
 751                 goto bad_block;
 752         if (error)
 753                 goto cleanup;
 754         if (!IS_LAST_ENTRY(s->first))
 755                 ext4_xattr_rehash(header(s->base), s->here);
 756
 757 inserted:
 758         if (!IS_LAST_ENTRY(s->first)) {
 759                 new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);
 760                 if (new_bh) {
 761                         /* We found an identical block in the cache. */
 762                         if (new_bh == bs->bh)
 763                                 ea_bdebug(new_bh, "keeping");
 764                         else {
 765                                 error = -ENOSPC;
 766                                 if (DLIMIT_ALLOC_BLOCK(inode, 1))
 767                                         goto cleanup;
 768                                 /* The old block is released after updating
 769                                    the inode. */
 770                                 error = -EDQUOT;
 771                                 if (DQUOT_ALLOC_BLOCK(inode, 1))
 772                                         goto cleanup_dlimit;
 773                                 error = ext4_journal_get_write_access(handle,
 774                                                                       new_bh);
 775                                 if (error)
 776                                         goto cleanup_dquot;
 777                                 lock_buffer(new_bh);
 778                                 BHDR(new_bh)->h_refcount = cpu_to_le32(1 +
 779                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 780                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
 781                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 782                                 unlock_buffer(new_bh);
 783                                 error = ext4_journal_dirty_metadata(handle,
 784                                                                     new_bh);
 785                                 if (error)
 786                                         goto cleanup_dquot;
 787                         }
 788                         mb_cache_entry_release(ce);
 789                         ce = NULL;
 790                 } else if (bs->bh && s->base == bs->bh->b_data) {
 791                         /* We were modifying this block in-place. */
 792                         ea_bdebug(bs->bh, "keeping this block");
 793                         new_bh = bs->bh;
 794                         get_bh(new_bh);
 795                 } else {
 796                         /* We need to allocate a new block */
 797                         ext4_fsblk_t goal = le32_to_cpu(
 798                                         EXT4_SB(sb)->s_es->s_first_data_block) +
 799                                 (ext4_fsblk_t)EXT4_I(inode)->i_block_group *
 800                                 EXT4_BLOCKS_PER_GROUP(sb);
 801                         ext4_fsblk_t block = ext4_new_block(handle, inode,
 802                                                         goal, &error);
 803                         if (error)
 804                                 goto cleanup;
 805                         ea_idebug(inode, "creating block %d", block);
 806
 807                         new_bh = sb_getblk(sb, block);
 808                         if (!new_bh) {
 809 getblk_failed:
 810                                 ext4_free_blocks(handle, inode, block, 1);
 811                                 error = -EIO;
 812                                 goto cleanup;
 813                         }
 814                         lock_buffer(new_bh);
 815                         error = ext4_journal_get_create_access(handle, new_bh);
 816                         if (error) {
 817                                 unlock_buffer(new_bh);
 818                                 goto getblk_failed;
 819                         }
 820                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
 821                         set_buffer_uptodate(new_bh);
 822                         unlock_buffer(new_bh);
 823                         ext4_xattr_cache_insert(new_bh);
 824                         error = ext4_journal_dirty_metadata(handle, new_bh);
 825                         if (error)
 826                                 goto cleanup;
 827                 }
 828         }
 829
 830         /* Update the inode. */
 831         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
 832
 833         /* Drop the previous xattr block. */
 834         if (bs->bh && bs->bh != new_bh)
 835                 ext4_xattr_release_block(handle, inode, bs->bh);
 836         error = 0;
 837
 838 cleanup:
 839         if (ce)
 840                 mb_cache_entry_release(ce);
 841         brelse(new_bh);
 842         if (!(bs->bh && s->base == bs->bh->b_data))
 843                 kfree(s->base);
 844
 845         return error;
 846
 847 cleanup_dquot:
 848         DQUOT_FREE_BLOCK(inode, 1);
 849 cleanup_dlimit:
 850         DLIMIT_FREE_BLOCK(inode, 1);
 851         goto cleanup;
 852
 853 bad_block:
 854         ext4_error(inode->i_sb, __FUNCTION__,
 855                    "inode %lu: bad block %llu", inode->i_ino,
 856                    EXT4_I(inode)->i_file_acl);
 857         goto cleanup;
 858
 859 #undef header
 860 }
 861
 862 struct ext4_xattr_ibody_find {
 863         struct ext4_xattr_search s;
 864         struct ext4_iloc iloc;
 865 };
 866
 867 static int
 868 ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
 869                       struct ext4_xattr_ibody_find *is)
 870 {
 871         struct ext4_xattr_ibody_header *header;
 872         struct ext4_inode *raw_inode;
 873         int error;
 874
 875         if (EXT4_I(inode)->i_extra_isize == 0)
 876                 return 0;
 877         raw_inode = ext4_raw_inode(&is->iloc);
 878         header = IHDR(inode, raw_inode);
 879         is->s.base = is->s.first = IFIRST(header);
 880         is->s.here = is->s.first;
 881         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 882         if (EXT4_I(inode)->i_state & EXT4_STATE_XATTR) {
 883                 error = ext4_xattr_check_names(IFIRST(header), is->s.end);
 884                 if (error)
 885                         return error;
 886                 /* Find the named attribute. */
 887                 error = ext4_xattr_find_entry(&is->s.here, i->name_index,
 888                                               i->name, is->s.end -
 889                                               (void *)is->s.base, 0);
 890                 if (error && error != -ENODATA)
 891                         return error;
 892                 is->s.not_found = error;
 893         }
 894         return 0;
 895 }
 896
 897 static int
 898 ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
 899                      struct ext4_xattr_info *i,
 900                      struct ext4_xattr_ibody_find *is)
 901 {
 902         struct ext4_xattr_ibody_header *header;
 903         struct ext4_xattr_search *s = &is->s;
 904         int error;
 905
 906         if (EXT4_I(inode)->i_extra_isize == 0)
 907                 return -ENOSPC;
 908         error = ext4_xattr_set_entry(i, s);
 909         if (error)
 910                 return error;
 911         header = IHDR(inode, ext4_raw_inode(&is->iloc));
 912         if (!IS_LAST_ENTRY(s->first)) {
 913                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
 914                 EXT4_I(inode)->i_state |= EXT4_STATE_XATTR;
 915         } else {
 916                 header->h_magic = cpu_to_le32(0);
 917                 EXT4_I(inode)->i_state &= ~EXT4_STATE_XATTR;
 918         }
 919         return 0;
 920 }
 921
 922 /*
 923  * ext4_xattr_set_handle()
 924  *
 925  * Create, replace or remove an extended attribute for this inode. Buffer
 926  * is NULL to remove an existing extended attribute, and non-NULL to
 927  * either replace an existing extended attribute, or create a new extended
 928  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 929  * specify that an extended attribute must exist and must not exist
 930  * previous to the call, respectively.
 931  *
 932  * Returns 0, or a negative error number on failure.
 933  */
 934 int
 935 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
 936                       const char *name, const void *value, size_t value_len,
 937                       int flags)
 938 {
 939         struct ext4_xattr_info i = {
 940                 .name_index = name_index,
 941                 .name = name,
 942                 .value = value,
 943                 .value_len = value_len,
 944
 945         };
 946         struct ext4_xattr_ibody_find is = {
 947                 .s = { .not_found = -ENODATA, },
 948         };
 949         struct ext4_xattr_block_find bs = {
 950                 .s = { .not_found = -ENODATA, },
 951         };
 952         int error;
 953
 954         if (!name)
 955                 return -EINVAL;
 956         if (strlen(name) > 255)
 957                 return -ERANGE;
 958         down_write(&EXT4_I(inode)->xattr_sem);
 959         error = ext4_get_inode_loc(inode, &is.iloc);
 960         if (error)
 961                 goto cleanup;
 962
 963         if (EXT4_I(inode)->i_state & EXT4_STATE_NEW) {
 964                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
 965                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
 966                 EXT4_I(inode)->i_state &= ~EXT4_STATE_NEW;
 967         }
 968
 969         error = ext4_xattr_ibody_find(inode, &i, &is);
 970         if (error)
 971                 goto cleanup;
 972         if (is.s.not_found)
 973                 error = ext4_xattr_block_find(inode, &i, &bs);
 974         if (error)
 975                 goto cleanup;
 976         if (is.s.not_found && bs.s.not_found) {
 977                 error = -ENODATA;
 978                 if (flags & XATTR_REPLACE)
 979                         goto cleanup;
 980                 error = 0;
 981                 if (!value)
 982                         goto cleanup;
 983         } else {
 984                 error = -EEXIST;
 985                 if (flags & XATTR_CREATE)
 986                         goto cleanup;
 987         }
 988         error = ext4_journal_get_write_access(handle, is.iloc.bh);
 989         if (error)
 990                 goto cleanup;
 991         if (!value) {
 992                 if (!is.s.not_found)
 993                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
 994                 else if (!bs.s.not_found)
 995                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
 996         } else {
 997                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
 998                 if (!error && !bs.s.not_found) {
 999                         i.value = NULL;
1000                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1001                 } else if (error == -ENOSPC) {
1002                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1003                         if (error)
1004                                 goto cleanup;
1005                         if (!is.s.not_found) {
1006                                 i.value = NULL;
1007                                 error = ext4_xattr_ibody_set(handle, inode, &i,
1008                                                              &is);
1009                         }
1010                 }
1011         }
1012         if (!error) {
1013                 ext4_xattr_update_super_block(handle, inode->i_sb);
1014                 inode->i_ctime = CURRENT_TIME_SEC;
1015                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
1016                 /*
1017                  * The bh is consumed by ext4_mark_iloc_dirty, even with
1018                  * error != 0.
1019                  */
1020                 is.iloc.bh = NULL;
1021                 if (IS_SYNC(inode))
1022                         handle->h_sync = 1;
1023         }
1024
1025 cleanup:
1026         brelse(is.iloc.bh);
1027         brelse(bs.bh);
1028         up_write(&EXT4_I(inode)->xattr_sem);
1029         return error;
1030 }
1031
1032 /*
1033  * ext4_xattr_set()
1034  *
1035  * Like ext4_xattr_set_handle, but start from an inode. This extended
1036  * attribute modification is a filesystem transaction by itself.
1037  *
1038  * Returns 0, or a negative error number on failure.
1039  */
1040 int
1041 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
1042                const void *value, size_t value_len, int flags)
1043 {
1044         handle_t *handle;
1045         int error, retries = 0;
1046
1047 retry:
1048         handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
1049         if (IS_ERR(handle)) {
1050                 error = PTR_ERR(handle);
1051         } else {
1052                 int error2;
1053
1054                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
1055                                               value, value_len, flags);
1056                 error2 = ext4_journal_stop(handle);
1057                 if (error == -ENOSPC &&
1058                     ext4_should_retry_alloc(inode->i_sb, &retries))
1059                         goto retry;
1060                 if (error == 0)
1061                         error = error2;
1062         }
1063
1064         return error;
1065 }
1066
1067 /*
1068  * ext4_xattr_delete_inode()
1069  *
1070  * Free extended attribute resources associated with this inode. This
1071  * is called immediately before an inode is freed. We have exclusive
1072  * access to the inode.
1073  */
1074 void
1075 ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)
1076 {
1077         struct buffer_head *bh = NULL;
1078
1079         if (!EXT4_I(inode)->i_file_acl)
1080                 goto cleanup;
1081         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1082         if (!bh) {
1083                 ext4_error(inode->i_sb, __FUNCTION__,
1084                         "inode %lu: block %llu read error", inode->i_ino,
1085                         EXT4_I(inode)->i_file_acl);
1086                 goto cleanup;
1087         }
1088         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
1089             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1090                 ext4_error(inode->i_sb, __FUNCTION__,
1091                         "inode %lu: bad block %llu", inode->i_ino,
1092                         EXT4_I(inode)->i_file_acl);
1093                 goto cleanup;
1094         }
1095         ext4_xattr_release_block(handle, inode, bh);
1096         EXT4_I(inode)->i_file_acl = 0;
1097
1098 cleanup:
1099         brelse(bh);
1100 }
1101
1102 /*
1103  * ext4_xattr_put_super()
1104  *
1105  * This is called when a file system is unmounted.
1106  */
1107 void
1108 ext4_xattr_put_super(struct super_block *sb)
1109 {
1110         mb_cache_shrink(sb->s_bdev);
1111 }
1112
1113 /*
1114  * ext4_xattr_cache_insert()
1115  *
1116  * Create a new entry in the extended attribute cache, and insert
1117  * it unless such an entry is already in the cache.
1118  *
1119  * Returns 0, or a negative error number on failure.
1120  */
1121 static void
1122 ext4_xattr_cache_insert(struct buffer_head *bh)
1123 {
1124         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1125         struct mb_cache_entry *ce;
1126         int error;
1127
1128         ce = mb_cache_entry_alloc(ext4_xattr_cache);
1129         if (!ce) {
1130                 ea_bdebug(bh, "out of memory");
1131                 return;
1132         }
1133         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
1134         if (error) {
1135                 mb_cache_entry_free(ce);
1136                 if (error == -EBUSY) {
1137                         ea_bdebug(bh, "already in cache");
1138                         error = 0;
1139                 }
1140         } else {
1141                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1142                 mb_cache_entry_release(ce);
1143         }
1144 }
1145
1146 /*
1147  * ext4_xattr_cmp()
1148  *
1149  * Compare two extended attribute blocks for equality.
1150  *
1151  * Returns 0 if the blocks are equal, 1 if they differ, and
1152  * a negative error number on errors.
1153  */
1154 static int
1155 ext4_xattr_cmp(struct ext4_xattr_header *header1,
1156                struct ext4_xattr_header *header2)
1157 {
1158         struct ext4_xattr_entry *entry1, *entry2;
1159
1160         entry1 = ENTRY(header1+1);
1161         entry2 = ENTRY(header2+1);
1162         while (!IS_LAST_ENTRY(entry1)) {
1163                 if (IS_LAST_ENTRY(entry2))
1164                         return 1;
1165                 if (entry1->e_hash != entry2->e_hash ||
1166                     entry1->e_name_index != entry2->e_name_index ||
1167                     entry1->e_name_len != entry2->e_name_len ||
1168                     entry1->e_value_size != entry2->e_value_size ||
1169                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1170                         return 1;
1171                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1172                         return -EIO;
1173                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1174                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1175                            le32_to_cpu(entry1->e_value_size)))
1176                         return 1;
1177
1178                 entry1 = EXT4_XATTR_NEXT(entry1);
1179                 entry2 = EXT4_XATTR_NEXT(entry2);
1180         }
1181         if (!IS_LAST_ENTRY(entry2))
1182                 return 1;
1183         return 0;
1184 }
1185
1186 /*
1187  * ext4_xattr_cache_find()
1188  *
1189  * Find an identical extended attribute block.
1190  *
1191  * Returns a pointer to the block found, or NULL if such a block was
1192  * not found or an error occurred.
1193  */
1194 static struct buffer_head *
1195 ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
1196                       struct mb_cache_entry **pce)
1197 {
1198         __u32 hash = le32_to_cpu(header->h_hash);
1199         struct mb_cache_entry *ce;
1200
1201         if (!header->h_hash)
1202                 return NULL;  /* never share */
1203         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1204 again:
1205         ce = mb_cache_entry_find_first(ext4_xattr_cache, 0,
1206                                        inode->i_sb->s_bdev, hash);
1207         while (ce) {
1208                 struct buffer_head *bh;
1209
1210                 if (IS_ERR(ce)) {
1211                         if (PTR_ERR(ce) == -EAGAIN)
1212                                 goto again;
1213                         break;
1214                 }
1215                 bh = sb_bread(inode->i_sb, ce->e_block);
1216                 if (!bh) {
1217                         ext4_error(inode->i_sb, __FUNCTION__,
1218                                 "inode %lu: block %lu read error",
1219                                 inode->i_ino, (unsigned long) ce->e_block);
1220                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1221                                 EXT4_XATTR_REFCOUNT_MAX) {
1222                         ea_idebug(inode, "block %lu refcount %d>=%d",
1223                                   (unsigned long) ce->e_block,
1224                                   le32_to_cpu(BHDR(bh)->h_refcount),
1225                                           EXT4_XATTR_REFCOUNT_MAX);
1226                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
1227                         *pce = ce;
1228                         return bh;
1229                 }
1230                 brelse(bh);
1231                 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
1232         }
1233         return NULL;
1234 }
1235
1236 #define NAME_HASH_SHIFT 5
1237 #define VALUE_HASH_SHIFT 16
1238
1239 /*
1240  * ext4_xattr_hash_entry()
1241  *
1242  * Compute the hash of an extended attribute.
1243  */
1244 static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
1245                                          struct ext4_xattr_entry *entry)
1246 {
1247         __u32 hash = 0;
1248         char *name = entry->e_name;
1249         int n;
1250
1251         for (n=0; n < entry->e_name_len; n++) {
1252                 hash = (hash << NAME_HASH_SHIFT) ^
1253                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1254                        *name++;
1255         }
1256
1257         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1258                 __le32 *value = (__le32 *)((char *)header +
1259                         le16_to_cpu(entry->e_value_offs));
1260                 for (n = (le32_to_cpu(entry->e_value_size) +
1261                      EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {
1262                         hash = (hash << VALUE_HASH_SHIFT) ^
1263                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1264                                le32_to_cpu(*value++);
1265                 }
1266         }
1267         entry->e_hash = cpu_to_le32(hash);
1268 }
1269
1270 #undef NAME_HASH_SHIFT
1271 #undef VALUE_HASH_SHIFT
1272
1273 #define BLOCK_HASH_SHIFT 16
1274
1275 /*
1276  * ext4_xattr_rehash()
1277  *
1278  * Re-compute the extended attribute hash value after an entry has changed.
1279  */
1280 static void ext4_xattr_rehash(struct ext4_xattr_header *header,
1281                               struct ext4_xattr_entry *entry)
1282 {
1283         struct ext4_xattr_entry *here;
1284         __u32 hash = 0;
1285
1286         ext4_xattr_hash_entry(header, entry);
1287         here = ENTRY(header+1);
1288         while (!IS_LAST_ENTRY(here)) {
1289                 if (!here->e_hash) {
1290                         /* Block is not shared if an entry's hash value == 0 */
1291                         hash = 0;
1292                         break;
1293                 }
1294                 hash = (hash << BLOCK_HASH_SHIFT) ^
1295                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1296                        le32_to_cpu(here->e_hash);
1297                 here = EXT4_XATTR_NEXT(here);
1298         }
1299         header->h_hash = cpu_to_le32(hash);
1300 }
1301
1302 #undef BLOCK_HASH_SHIFT
1303
1304 int __init
1305 init_ext4_xattr(void)
1306 {
1307         ext4_xattr_cache = mb_cache_create("ext4_xattr", NULL,
1308                 sizeof(struct mb_cache_entry) +
1309                 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1310         if (!ext4_xattr_cache)
1311                 return -ENOMEM;
1312         return 0;
1313 }
1314
1315 void
1316 exit_ext4_xattr(void)
1317 {
1318         if (ext4_xattr_cache)
1319                 mb_cache_destroy(ext4_xattr_cache);
1320         ext4_xattr_cache = NULL;
1321 }