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/mbcache.h>
  57 #include <linux/quotaops.h>
  58 #include "ext4_jbd2.h"
  59 #include "ext4.h"
  60 #include "xattr.h"
  61 #include "acl.h"
  62
  63 #ifdef EXT4_XATTR_DEBUG
  64 # define ea_idebug(inode, f...) do { \
  65                 printk(KERN_DEBUG "inode %s:%lu: ", \
  66                         inode->i_sb->s_id, inode->i_ino); \
  67                 printk(f); \
  68                 printk("\n"); \
  69         } while (0)
  70 # define ea_bdebug(bh, f...) do { \
  71                 char b[BDEVNAME_SIZE]; \
  72                 printk(KERN_DEBUG "block %s:%lu: ", \
  73                         bdevname(bh->b_bdev, b), \
  74                         (unsigned long) bh->b_blocknr); \
  75                 printk(f); \
  76                 printk("\n"); \
  77         } while (0)
  78 #else
  79 # define ea_idebug(inode, fmt, ...)     no_printk(fmt, ##__VA_ARGS__)
  80 # define ea_bdebug(bh, fmt, ...)        no_printk(fmt, ##__VA_ARGS__)
  81 #endif
  82
  83 static void ext4_xattr_cache_insert(struct mb_cache *, struct buffer_head *);
  84 static struct buffer_head *ext4_xattr_cache_find(struct inode *,
  85                                                  struct ext4_xattr_header *,
  86                                                  struct mb_cache_entry **);
  87 static void ext4_xattr_rehash(struct ext4_xattr_header *,
  88                               struct ext4_xattr_entry *);
  89 static int ext4_xattr_list(struct dentry *dentry, char *buffer,
  90                            size_t buffer_size);
  91
  92 static const struct xattr_handler *ext4_xattr_handler_map[] = {
  93         [EXT4_XATTR_INDEX_USER]              = &ext4_xattr_user_handler,
  94 #ifdef CONFIG_EXT4_FS_POSIX_ACL
  95         [EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &posix_acl_access_xattr_handler,
  96         [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
  97 #endif
  98         [EXT4_XATTR_INDEX_TRUSTED]           = &ext4_xattr_trusted_handler,
  99 #ifdef CONFIG_EXT4_FS_SECURITY
 100         [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
 101 #endif
 102 };
 103
 104 const struct xattr_handler *ext4_xattr_handlers[] = {
 105         &ext4_xattr_user_handler,
 106         &ext4_xattr_trusted_handler,
 107 #ifdef CONFIG_EXT4_FS_POSIX_ACL
 108         &posix_acl_access_xattr_handler,
 109         &posix_acl_default_xattr_handler,
 110 #endif
 111 #ifdef CONFIG_EXT4_FS_SECURITY
 112         &ext4_xattr_security_handler,
 113 #endif
 114         NULL
 115 };
 116
 117 #define EXT4_GET_MB_CACHE(inode)        (((struct ext4_sb_info *) \
 118                                 inode->i_sb->s_fs_info)->s_mb_cache)
 119
 120 static __le32 ext4_xattr_block_csum(struct inode *inode,
 121                                     sector_t block_nr,
 122                                     struct ext4_xattr_header *hdr)
 123 {
 124         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 125         __u32 csum;
 126         __le32 save_csum;
 127         __le64 dsk_block_nr = cpu_to_le64(block_nr);
 128
 129         save_csum = hdr->h_checksum;
 130         hdr->h_checksum = 0;
 131         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&dsk_block_nr,
 132                            sizeof(dsk_block_nr));
 133         csum = ext4_chksum(sbi, csum, (__u8 *)hdr,
 134                            EXT4_BLOCK_SIZE(inode->i_sb));
 135
 136         hdr->h_checksum = save_csum;
 137         return cpu_to_le32(csum);
 138 }
 139
 140 static int ext4_xattr_block_csum_verify(struct inode *inode,
 141                                         sector_t block_nr,
 142                                         struct ext4_xattr_header *hdr)
 143 {
 144         if (ext4_has_metadata_csum(inode->i_sb) &&
 145             (hdr->h_checksum != ext4_xattr_block_csum(inode, block_nr, hdr)))
 146                 return 0;
 147         return 1;
 148 }
 149
 150 static void ext4_xattr_block_csum_set(struct inode *inode,
 151                                       sector_t block_nr,
 152                                       struct ext4_xattr_header *hdr)
 153 {
 154         if (!ext4_has_metadata_csum(inode->i_sb))
 155                 return;
 156
 157         hdr->h_checksum = ext4_xattr_block_csum(inode, block_nr, hdr);
 158 }
 159
 160 static inline int ext4_handle_dirty_xattr_block(handle_t *handle,
 161                                                 struct inode *inode,
 162                                                 struct buffer_head *bh)
 163 {
 164         ext4_xattr_block_csum_set(inode, bh->b_blocknr, BHDR(bh));
 165         return ext4_handle_dirty_metadata(handle, inode, bh);
 166 }
 167
 168 static inline const struct xattr_handler *
 169 ext4_xattr_handler(int name_index)
 170 {
 171         const struct xattr_handler *handler = NULL;
 172
 173         if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
 174                 handler = ext4_xattr_handler_map[name_index];
 175         return handler;
 176 }
 177
 178 /*
 179  * Inode operation listxattr()
 180  *
 181  * dentry->d_inode->i_mutex: don't care
 182  */
 183 ssize_t
 184 ext4_listxattr(struct dentry *dentry, char *buffer, size_t size)
 185 {
 186         return ext4_xattr_list(dentry, buffer, size);
 187 }
 188
 189 static int
 190 ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end,
 191                        void *value_start)
 192 {
 193         struct ext4_xattr_entry *e = entry;
 194
 195         while (!IS_LAST_ENTRY(e)) {
 196                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(e);
 197                 if ((void *)next >= end)
 198                         return -EIO;
 199                 e = next;
 200         }
 201
 202         while (!IS_LAST_ENTRY(entry)) {
 203                 if (entry->e_value_size != 0 &&
 204                     (value_start + le16_to_cpu(entry->e_value_offs) <
 205                      (void *)e + sizeof(__u32) ||
 206                      value_start + le16_to_cpu(entry->e_value_offs) +
 207                     le32_to_cpu(entry->e_value_size) > end))
 208                         return -EIO;
 209                 entry = EXT4_XATTR_NEXT(entry);
 210         }
 211
 212         return 0;
 213 }
 214
 215 static inline int
 216 ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh)
 217 {
 218         int error;
 219
 220         if (buffer_verified(bh))
 221                 return 0;
 222
 223         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
 224             BHDR(bh)->h_blocks != cpu_to_le32(1))
 225                 return -EIO;
 226         if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh)))
 227                 return -EIO;
 228         error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size,
 229                                        bh->b_data);
 230         if (!error)
 231                 set_buffer_verified(bh);
 232         return error;
 233 }
 234
 235 static inline int
 236 ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size)
 237 {
 238         size_t value_size = le32_to_cpu(entry->e_value_size);
 239
 240         if (entry->e_value_block != 0 || value_size > size ||
 241             le16_to_cpu(entry->e_value_offs) + value_size > size)
 242                 return -EIO;
 243         return 0;
 244 }
 245
 246 static int
 247 ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
 248                       const char *name, size_t size, int sorted)
 249 {
 250         struct ext4_xattr_entry *entry;
 251         size_t name_len;
 252         int cmp = 1;
 253
 254         if (name == NULL)
 255                 return -EINVAL;
 256         name_len = strlen(name);
 257         entry = *pentry;
 258         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 259                 cmp = name_index - entry->e_name_index;
 260                 if (!cmp)
 261                         cmp = name_len - entry->e_name_len;
 262                 if (!cmp)
 263                         cmp = memcmp(name, entry->e_name, name_len);
 264                 if (cmp <= 0 && (sorted || cmp == 0))
 265                         break;
 266         }
 267         *pentry = entry;
 268         if (!cmp && ext4_xattr_check_entry(entry, size))
 269                         return -EIO;
 270         return cmp ? -ENODATA : 0;
 271 }
 272
 273 static int
 274 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
 275                      void *buffer, size_t buffer_size)
 276 {
 277         struct buffer_head *bh = NULL;
 278         struct ext4_xattr_entry *entry;
 279         size_t size;
 280         int error;
 281         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 282
 283         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 284                   name_index, name, buffer, (long)buffer_size);
 285
 286         error = -ENODATA;
 287         if (!EXT4_I(inode)->i_file_acl)
 288                 goto cleanup;
 289         ea_idebug(inode, "reading block %llu",
 290                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 291         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 292         if (!bh)
 293                 goto cleanup;
 294         ea_bdebug(bh, "b_count=%d, refcount=%d",
 295                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 296         if (ext4_xattr_check_block(inode, bh)) {
 297 bad_block:
 298                 EXT4_ERROR_INODE(inode, "bad block %llu",
 299                                  EXT4_I(inode)->i_file_acl);
 300                 error = -EIO;
 301                 goto cleanup;
 302         }
 303         ext4_xattr_cache_insert(ext4_mb_cache, bh);
 304         entry = BFIRST(bh);
 305         error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
 306         if (error == -EIO)
 307                 goto bad_block;
 308         if (error)
 309                 goto cleanup;
 310         size = le32_to_cpu(entry->e_value_size);
 311         if (buffer) {
 312                 error = -ERANGE;
 313                 if (size > buffer_size)
 314                         goto cleanup;
 315                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
 316                        size);
 317         }
 318         error = size;
 319
 320 cleanup:
 321         brelse(bh);
 322         return error;
 323 }
 324
 325 int
 326 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 327                      void *buffer, size_t buffer_size)
 328 {
 329         struct ext4_xattr_ibody_header *header;
 330         struct ext4_xattr_entry *entry;
 331         struct ext4_inode *raw_inode;
 332         struct ext4_iloc iloc;
 333         size_t size;
 334         void *end;
 335         int error;
 336
 337         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 338                 return -ENODATA;
 339         error = ext4_get_inode_loc(inode, &iloc);
 340         if (error)
 341                 return error;
 342         raw_inode = ext4_raw_inode(&iloc);
 343         header = IHDR(inode, raw_inode);
 344         entry = IFIRST(header);
 345         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 346         error = ext4_xattr_check_names(entry, end, entry);
 347         if (error)
 348                 goto cleanup;
 349         error = ext4_xattr_find_entry(&entry, name_index, name,
 350                                       end - (void *)entry, 0);
 351         if (error)
 352                 goto cleanup;
 353         size = le32_to_cpu(entry->e_value_size);
 354         if (buffer) {
 355                 error = -ERANGE;
 356                 if (size > buffer_size)
 357                         goto cleanup;
 358                 memcpy(buffer, (void *)IFIRST(header) +
 359                        le16_to_cpu(entry->e_value_offs), size);
 360         }
 361         error = size;
 362
 363 cleanup:
 364         brelse(iloc.bh);
 365         return error;
 366 }
 367
 368 /*
 369  * ext4_xattr_get()
 370  *
 371  * Copy an extended attribute into the buffer
 372  * provided, or compute the buffer size required.
 373  * Buffer is NULL to compute the size of the buffer required.
 374  *
 375  * Returns a negative error number on failure, or the number of bytes
 376  * used / required on success.
 377  */
 378 int
 379 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
 380                void *buffer, size_t buffer_size)
 381 {
 382         int error;
 383
 384         if (strlen(name) > 255)
 385                 return -ERANGE;
 386
 387         down_read(&EXT4_I(inode)->xattr_sem);
 388         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
 389                                      buffer_size);
 390         if (error == -ENODATA)
 391                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
 392                                              buffer_size);
 393         up_read(&EXT4_I(inode)->xattr_sem);
 394         return error;
 395 }
 396
 397 static int
 398 ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,
 399                         char *buffer, size_t buffer_size)
 400 {
 401         size_t rest = buffer_size;
 402
 403         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 404                 const struct xattr_handler *handler =
 405                         ext4_xattr_handler(entry->e_name_index);
 406
 407                 if (handler) {
 408                         size_t size = handler->list(dentry, buffer, rest,
 409                                                     entry->e_name,
 410                                                     entry->e_name_len,
 411                                                     handler->flags);
 412                         if (buffer) {
 413                                 if (size > rest)
 414                                         return -ERANGE;
 415                                 buffer += size;
 416                         }
 417                         rest -= size;
 418                 }
 419         }
 420         return buffer_size - rest;
 421 }
 422
 423 static int
 424 ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 425 {
 426         struct inode *inode = dentry->d_inode;
 427         struct buffer_head *bh = NULL;
 428         int error;
 429         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 430
 431         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 432                   buffer, (long)buffer_size);
 433
 434         error = 0;
 435         if (!EXT4_I(inode)->i_file_acl)
 436                 goto cleanup;
 437         ea_idebug(inode, "reading block %llu",
 438                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 439         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 440         error = -EIO;
 441         if (!bh)
 442                 goto cleanup;
 443         ea_bdebug(bh, "b_count=%d, refcount=%d",
 444                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 445         if (ext4_xattr_check_block(inode, bh)) {
 446                 EXT4_ERROR_INODE(inode, "bad block %llu",
 447                                  EXT4_I(inode)->i_file_acl);
 448                 error = -EIO;
 449                 goto cleanup;
 450         }
 451         ext4_xattr_cache_insert(ext4_mb_cache, bh);
 452         error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
 453
 454 cleanup:
 455         brelse(bh);
 456
 457         return error;
 458 }
 459
 460 static int
 461 ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 462 {
 463         struct inode *inode = dentry->d_inode;
 464         struct ext4_xattr_ibody_header *header;
 465         struct ext4_inode *raw_inode;
 466         struct ext4_iloc iloc;
 467         void *end;
 468         int error;
 469
 470         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 471                 return 0;
 472         error = ext4_get_inode_loc(inode, &iloc);
 473         if (error)
 474                 return error;
 475         raw_inode = ext4_raw_inode(&iloc);
 476         header = IHDR(inode, raw_inode);
 477         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 478         error = ext4_xattr_check_names(IFIRST(header), end, IFIRST(header));
 479         if (error)
 480                 goto cleanup;
 481         error = ext4_xattr_list_entries(dentry, IFIRST(header),
 482                                         buffer, buffer_size);
 483
 484 cleanup:
 485         brelse(iloc.bh);
 486         return error;
 487 }
 488
 489 /*
 490  * ext4_xattr_list()
 491  *
 492  * Copy a list of attribute names into the buffer
 493  * provided, or compute the buffer size required.
 494  * Buffer is NULL to compute the size of the buffer required.
 495  *
 496  * Returns a negative error number on failure, or the number of bytes
 497  * used / required on success.
 498  */
 499 static int
 500 ext4_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 501 {
 502         int ret, ret2;
 503
 504         down_read(&EXT4_I(dentry->d_inode)->xattr_sem);
 505         ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size);
 506         if (ret < 0)
 507                 goto errout;
 508         if (buffer) {
 509                 buffer += ret;
 510                 buffer_size -= ret;
 511         }
 512         ret = ext4_xattr_block_list(dentry, buffer, buffer_size);
 513         if (ret < 0)
 514                 goto errout;
 515         ret += ret2;
 516 errout:
 517         up_read(&EXT4_I(dentry->d_inode)->xattr_sem);
 518         return ret;
 519 }
 520
 521 /*
 522  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 523  * not set, set it.
 524  */
 525 static void ext4_xattr_update_super_block(handle_t *handle,
 526                                           struct super_block *sb)
 527 {
 528         if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR))
 529                 return;
 530
 531         BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
 532         if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
 533                 EXT4_SET_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR);
 534                 ext4_handle_dirty_super(handle, sb);
 535         }
 536 }
 537
 538 /*
 539  * Release the xattr block BH: If the reference count is > 1, decrement it;
 540  * otherwise free the block.
 541  */
 542 static void
 543 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
 544                          struct buffer_head *bh)
 545 {
 546         struct mb_cache_entry *ce = NULL;
 547         int error = 0;
 548         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 549
 550         ce = mb_cache_entry_get(ext4_mb_cache, bh->b_bdev, bh->b_blocknr);
 551         BUFFER_TRACE(bh, "get_write_access");
 552         error = ext4_journal_get_write_access(handle, bh);
 553         if (error)
 554                 goto out;
 555
 556         lock_buffer(bh);
 557         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
 558                 ea_bdebug(bh, "refcount now=0; freeing");
 559                 if (ce)
 560                         mb_cache_entry_free(ce);
 561                 get_bh(bh);
 562                 unlock_buffer(bh);
 563                 ext4_free_blocks(handle, inode, bh, 0, 1,
 564                                  EXT4_FREE_BLOCKS_METADATA |
 565                                  EXT4_FREE_BLOCKS_FORGET);
 566         } else {
 567                 le32_add_cpu(&BHDR(bh)->h_refcount, -1);
 568                 if (ce)
 569                         mb_cache_entry_release(ce);
 570                 /*
 571                  * Beware of this ugliness: Releasing of xattr block references
 572                  * from different inodes can race and so we have to protect
 573                  * from a race where someone else frees the block (and releases
 574                  * its journal_head) before we are done dirtying the buffer. In
 575                  * nojournal mode this race is harmless and we actually cannot
 576                  * call ext4_handle_dirty_xattr_block() with locked buffer as
 577                  * that function can call sync_dirty_buffer() so for that case
 578                  * we handle the dirtying after unlocking the buffer.
 579                  */
 580                 if (ext4_handle_valid(handle))
 581                         error = ext4_handle_dirty_xattr_block(handle, inode,
 582                                                               bh);
 583                 unlock_buffer(bh);
 584                 if (!ext4_handle_valid(handle))
 585                         error = ext4_handle_dirty_xattr_block(handle, inode,
 586                                                               bh);
 587                 if (IS_SYNC(inode))
 588                         ext4_handle_sync(handle);
 589                 dquot_free_block(inode, EXT4_C2B(EXT4_SB(inode->i_sb), 1));
 590                 ea_bdebug(bh, "refcount now=%d; releasing",
 591                           le32_to_cpu(BHDR(bh)->h_refcount));
 592         }
 593 out:
 594         ext4_std_error(inode->i_sb, error);
 595         return;
 596 }
 597
 598 /*
 599  * Find the available free space for EAs. This also returns the total number of
 600  * bytes used by EA entries.
 601  */
 602 static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
 603                                     size_t *min_offs, void *base, int *total)
 604 {
 605         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 606                 if (!last->e_value_block && last->e_value_size) {
 607                         size_t offs = le16_to_cpu(last->e_value_offs);
 608                         if (offs < *min_offs)
 609                                 *min_offs = offs;
 610                 }
 611                 if (total)
 612                         *total += EXT4_XATTR_LEN(last->e_name_len);
 613         }
 614         return (*min_offs - ((void *)last - base) - sizeof(__u32));
 615 }
 616
 617 static int
 618 ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
 619 {
 620         struct ext4_xattr_entry *last;
 621         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
 622
 623         /* Compute min_offs and last. */
 624         last = s->first;
 625         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 626                 if (!last->e_value_block && last->e_value_size) {
 627                         size_t offs = le16_to_cpu(last->e_value_offs);
 628                         if (offs < min_offs)
 629                                 min_offs = offs;
 630                 }
 631         }
 632         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
 633         if (!s->not_found) {
 634                 if (!s->here->e_value_block && s->here->e_value_size) {
 635                         size_t size = le32_to_cpu(s->here->e_value_size);
 636                         free += EXT4_XATTR_SIZE(size);
 637                 }
 638                 free += EXT4_XATTR_LEN(name_len);
 639         }
 640         if (i->value) {
 641                 if (free < EXT4_XATTR_SIZE(i->value_len) ||
 642                     free < EXT4_XATTR_LEN(name_len) +
 643                            EXT4_XATTR_SIZE(i->value_len))
 644                         return -ENOSPC;
 645         }
 646
 647         if (i->value && s->not_found) {
 648                 /* Insert the new name. */
 649                 size_t size = EXT4_XATTR_LEN(name_len);
 650                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
 651                 memmove((void *)s->here + size, s->here, rest);
 652                 memset(s->here, 0, size);
 653                 s->here->e_name_index = i->name_index;
 654                 s->here->e_name_len = name_len;
 655                 memcpy(s->here->e_name, i->name, name_len);
 656         } else {
 657                 if (!s->here->e_value_block && s->here->e_value_size) {
 658                         void *first_val = s->base + min_offs;
 659                         size_t offs = le16_to_cpu(s->here->e_value_offs);
 660                         void *val = s->base + offs;
 661                         size_t size = EXT4_XATTR_SIZE(
 662                                 le32_to_cpu(s->here->e_value_size));
 663
 664                         if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
 665                                 /* The old and the new value have the same
 666                                    size. Just replace. */
 667                                 s->here->e_value_size =
 668                                         cpu_to_le32(i->value_len);
 669                                 if (i->value == EXT4_ZERO_XATTR_VALUE) {
 670                                         memset(val, 0, size);
 671                                 } else {
 672                                         /* Clear pad bytes first. */
 673                                         memset(val + size - EXT4_XATTR_PAD, 0,
 674                                                EXT4_XATTR_PAD);
 675                                         memcpy(val, i->value, i->value_len);
 676                                 }
 677                                 return 0;
 678                         }
 679
 680                         /* Remove the old value. */
 681                         memmove(first_val + size, first_val, val - first_val);
 682                         memset(first_val, 0, size);
 683                         s->here->e_value_size = 0;
 684                         s->here->e_value_offs = 0;
 685                         min_offs += size;
 686
 687                         /* Adjust all value offsets. */
 688                         last = s->first;
 689                         while (!IS_LAST_ENTRY(last)) {
 690                                 size_t o = le16_to_cpu(last->e_value_offs);
 691                                 if (!last->e_value_block &&
 692                                     last->e_value_size && o < offs)
 693                                         last->e_value_offs =
 694                                                 cpu_to_le16(o + size);
 695                                 last = EXT4_XATTR_NEXT(last);
 696                         }
 697                 }
 698                 if (!i->value) {
 699                         /* Remove the old name. */
 700                         size_t size = EXT4_XATTR_LEN(name_len);
 701                         last = ENTRY((void *)last - size);
 702                         memmove(s->here, (void *)s->here + size,
 703                                 (void *)last - (void *)s->here + sizeof(__u32));
 704                         memset(last, 0, size);
 705                 }
 706         }
 707
 708         if (i->value) {
 709                 /* Insert the new value. */
 710                 s->here->e_value_size = cpu_to_le32(i->value_len);
 711                 if (i->value_len) {
 712                         size_t size = EXT4_XATTR_SIZE(i->value_len);
 713                         void *val = s->base + min_offs - size;
 714                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
 715                         if (i->value == EXT4_ZERO_XATTR_VALUE) {
 716                                 memset(val, 0, size);
 717                         } else {
 718                                 /* Clear the pad bytes first. */
 719                                 memset(val + size - EXT4_XATTR_PAD, 0,
 720                                        EXT4_XATTR_PAD);
 721                                 memcpy(val, i->value, i->value_len);
 722                         }
 723                 }
 724         }
 725         return 0;
 726 }
 727
 728 struct ext4_xattr_block_find {
 729         struct ext4_xattr_search s;
 730         struct buffer_head *bh;
 731 };
 732
 733 static int
 734 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
 735                       struct ext4_xattr_block_find *bs)
 736 {
 737         struct super_block *sb = inode->i_sb;
 738         int error;
 739
 740         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
 741                   i->name_index, i->name, i->value, (long)i->value_len);
 742
 743         if (EXT4_I(inode)->i_file_acl) {
 744                 /* The inode already has an extended attribute block. */
 745                 bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);
 746                 error = -EIO;
 747                 if (!bs->bh)
 748                         goto cleanup;
 749                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
 750                         atomic_read(&(bs->bh->b_count)),
 751                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
 752                 if (ext4_xattr_check_block(inode, bs->bh)) {
 753                         EXT4_ERROR_INODE(inode, "bad block %llu",
 754                                          EXT4_I(inode)->i_file_acl);
 755                         error = -EIO;
 756                         goto cleanup;
 757                 }
 758                 /* Find the named attribute. */
 759                 bs->s.base = BHDR(bs->bh);
 760                 bs->s.first = BFIRST(bs->bh);
 761                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
 762                 bs->s.here = bs->s.first;
 763                 error = ext4_xattr_find_entry(&bs->s.here, i->name_index,
 764                                               i->name, bs->bh->b_size, 1);
 765                 if (error && error != -ENODATA)
 766                         goto cleanup;
 767                 bs->s.not_found = error;
 768         }
 769         error = 0;
 770
 771 cleanup:
 772         return error;
 773 }
 774
 775 static int
 776 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
 777                      struct ext4_xattr_info *i,
 778                      struct ext4_xattr_block_find *bs)
 779 {
 780         struct super_block *sb = inode->i_sb;
 781         struct buffer_head *new_bh = NULL;
 782         struct ext4_xattr_search *s = &bs->s;
 783         struct mb_cache_entry *ce = NULL;
 784         int error = 0;
 785         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 786
 787 #define header(x) ((struct ext4_xattr_header *)(x))
 788
 789         if (i->value && i->value_len > sb->s_blocksize)
 790                 return -ENOSPC;
 791         if (s->base) {
 792                 ce = mb_cache_entry_get(ext4_mb_cache, bs->bh->b_bdev,
 793                                         bs->bh->b_blocknr);
 794                 BUFFER_TRACE(bs->bh, "get_write_access");
 795                 error = ext4_journal_get_write_access(handle, bs->bh);
 796                 if (error)
 797                         goto cleanup;
 798                 lock_buffer(bs->bh);
 799
 800                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 801                         if (ce) {
 802                                 mb_cache_entry_free(ce);
 803                                 ce = NULL;
 804                         }
 805                         ea_bdebug(bs->bh, "modifying in-place");
 806                         error = ext4_xattr_set_entry(i, s);
 807                         if (!error) {
 808                                 if (!IS_LAST_ENTRY(s->first))
 809                                         ext4_xattr_rehash(header(s->base),
 810                                                           s->here);
 811                                 ext4_xattr_cache_insert(ext4_mb_cache,
 812                                         bs->bh);
 813                         }
 814                         unlock_buffer(bs->bh);
 815                         if (error == -EIO)
 816                                 goto bad_block;
 817                         if (!error)
 818                                 error = ext4_handle_dirty_xattr_block(handle,
 819                                                                       inode,
 820                                                                       bs->bh);
 821                         if (error)
 822                                 goto cleanup;
 823                         goto inserted;
 824                 } else {
 825                         int offset = (char *)s->here - bs->bh->b_data;
 826
 827                         unlock_buffer(bs->bh);
 828                         if (ce) {
 829                                 mb_cache_entry_release(ce);
 830                                 ce = NULL;
 831                         }
 832                         ea_bdebug(bs->bh, "cloning");
 833                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
 834                         error = -ENOMEM;
 835                         if (s->base == NULL)
 836                                 goto cleanup;
 837                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 838                         s->first = ENTRY(header(s->base)+1);
 839                         header(s->base)->h_refcount = cpu_to_le32(1);
 840                         s->here = ENTRY(s->base + offset);
 841                         s->end = s->base + bs->bh->b_size;
 842                 }
 843         } else {
 844                 /* Allocate a buffer where we construct the new block. */
 845                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
 846                 /* assert(header == s->base) */
 847                 error = -ENOMEM;
 848                 if (s->base == NULL)
 849                         goto cleanup;
 850                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
 851                 header(s->base)->h_blocks = cpu_to_le32(1);
 852                 header(s->base)->h_refcount = cpu_to_le32(1);
 853                 s->first = ENTRY(header(s->base)+1);
 854                 s->here = ENTRY(header(s->base)+1);
 855                 s->end = s->base + sb->s_blocksize;
 856         }
 857
 858         error = ext4_xattr_set_entry(i, s);
 859         if (error == -EIO)
 860                 goto bad_block;
 861         if (error)
 862                 goto cleanup;
 863         if (!IS_LAST_ENTRY(s->first))
 864                 ext4_xattr_rehash(header(s->base), s->here);
 865
 866 inserted:
 867         if (!IS_LAST_ENTRY(s->first)) {
 868                 new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);
 869                 if (new_bh) {
 870                         /* We found an identical block in the cache. */
 871                         if (new_bh == bs->bh)
 872                                 ea_bdebug(new_bh, "keeping");
 873                         else {
 874                                 /* The old block is released after updating
 875                                    the inode. */
 876                                 error = dquot_alloc_block(inode,
 877                                                 EXT4_C2B(EXT4_SB(sb), 1));
 878                                 if (error)
 879                                         goto cleanup;
 880                                 BUFFER_TRACE(new_bh, "get_write_access");
 881                                 error = ext4_journal_get_write_access(handle,
 882                                                                       new_bh);
 883                                 if (error)
 884                                         goto cleanup_dquot;
 885                                 lock_buffer(new_bh);
 886                                 le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
 887                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
 888                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 889                                 unlock_buffer(new_bh);
 890                                 error = ext4_handle_dirty_xattr_block(handle,
 891                                                                       inode,
 892                                                                       new_bh);
 893                                 if (error)
 894                                         goto cleanup_dquot;
 895                         }
 896                         mb_cache_entry_release(ce);
 897                         ce = NULL;
 898                 } else if (bs->bh && s->base == bs->bh->b_data) {
 899                         /* We were modifying this block in-place. */
 900                         ea_bdebug(bs->bh, "keeping this block");
 901                         new_bh = bs->bh;
 902                         get_bh(new_bh);
 903                 } else {
 904                         /* We need to allocate a new block */
 905                         ext4_fsblk_t goal, block;
 906
 907                         goal = ext4_group_first_block_no(sb,
 908                                                 EXT4_I(inode)->i_block_group);
 909
 910                         /* non-extent files can't have physical blocks past 2^32 */
 911                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 912                                 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
 913
 914                         block = ext4_new_meta_blocks(handle, inode, goal, 0,
 915                                                      NULL, &error);
 916                         if (error)
 917                                 goto cleanup;
 918
 919                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 920                                 BUG_ON(block > EXT4_MAX_BLOCK_FILE_PHYS);
 921
 922                         ea_idebug(inode, "creating block %llu",
 923                                   (unsigned long long)block);
 924
 925                         new_bh = sb_getblk(sb, block);
 926                         if (unlikely(!new_bh)) {
 927                                 error = -ENOMEM;
 928 getblk_failed:
 929                                 ext4_free_blocks(handle, inode, NULL, block, 1,
 930                                                  EXT4_FREE_BLOCKS_METADATA);
 931                                 goto cleanup;
 932                         }
 933                         lock_buffer(new_bh);
 934                         error = ext4_journal_get_create_access(handle, new_bh);
 935                         if (error) {
 936                                 unlock_buffer(new_bh);
 937                                 error = -EIO;
 938                                 goto getblk_failed;
 939                         }
 940                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
 941                         set_buffer_uptodate(new_bh);
 942                         unlock_buffer(new_bh);
 943                         ext4_xattr_cache_insert(ext4_mb_cache, new_bh);
 944                         error = ext4_handle_dirty_xattr_block(handle,
 945                                                               inode, new_bh);
 946                         if (error)
 947                                 goto cleanup;
 948                 }
 949         }
 950
 951         /* Update the inode. */
 952         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
 953
 954         /* Drop the previous xattr block. */
 955         if (bs->bh && bs->bh != new_bh)
 956                 ext4_xattr_release_block(handle, inode, bs->bh);
 957         error = 0;
 958
 959 cleanup:
 960         if (ce)
 961                 mb_cache_entry_release(ce);
 962         brelse(new_bh);
 963         if (!(bs->bh && s->base == bs->bh->b_data))
 964                 kfree(s->base);
 965
 966         return error;
 967
 968 cleanup_dquot:
 969         dquot_free_block(inode, EXT4_C2B(EXT4_SB(sb), 1));
 970         goto cleanup;
 971
 972 bad_block:
 973         EXT4_ERROR_INODE(inode, "bad block %llu",
 974                          EXT4_I(inode)->i_file_acl);
 975         goto cleanup;
 976
 977 #undef header
 978 }
 979
 980 int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
 981                           struct ext4_xattr_ibody_find *is)
 982 {
 983         struct ext4_xattr_ibody_header *header;
 984         struct ext4_inode *raw_inode;
 985         int error;
 986
 987         if (EXT4_I(inode)->i_extra_isize == 0)
 988                 return 0;
 989         raw_inode = ext4_raw_inode(&is->iloc);
 990         header = IHDR(inode, raw_inode);
 991         is->s.base = is->s.first = IFIRST(header);
 992         is->s.here = is->s.first;
 993         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 994         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
 995                 error = ext4_xattr_check_names(IFIRST(header), is->s.end,
 996                                                IFIRST(header));
 997                 if (error)
 998                         return error;
 999                 /* Find the named attribute. */
1000                 error = ext4_xattr_find_entry(&is->s.here, i->name_index,
1001                                               i->name, is->s.end -
1002                                               (void *)is->s.base, 0);
1003                 if (error && error != -ENODATA)
1004                         return error;
1005                 is->s.not_found = error;
1006         }
1007         return 0;
1008 }
1009
1010 int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode,
1011                                 struct ext4_xattr_info *i,
1012                                 struct ext4_xattr_ibody_find *is)
1013 {
1014         struct ext4_xattr_ibody_header *header;
1015         struct ext4_xattr_search *s = &is->s;
1016         int error;
1017
1018         if (EXT4_I(inode)->i_extra_isize == 0)
1019                 return -ENOSPC;
1020         error = ext4_xattr_set_entry(i, s);
1021         if (error) {
1022                 if (error == -ENOSPC &&
1023                     ext4_has_inline_data(inode)) {
1024                         error = ext4_try_to_evict_inline_data(handle, inode,
1025                                         EXT4_XATTR_LEN(strlen(i->name) +
1026                                         EXT4_XATTR_SIZE(i->value_len)));
1027                         if (error)
1028                                 return error;
1029                         error = ext4_xattr_ibody_find(inode, i, is);
1030                         if (error)
1031                                 return error;
1032                         error = ext4_xattr_set_entry(i, s);
1033                 }
1034                 if (error)
1035                         return error;
1036         }
1037         header = IHDR(inode, ext4_raw_inode(&is->iloc));
1038         if (!IS_LAST_ENTRY(s->first)) {
1039                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1040                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
1041         } else {
1042                 header->h_magic = cpu_to_le32(0);
1043                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
1044         }
1045         return 0;
1046 }
1047
1048 static int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
1049                                 struct ext4_xattr_info *i,
1050                                 struct ext4_xattr_ibody_find *is)
1051 {
1052         struct ext4_xattr_ibody_header *header;
1053         struct ext4_xattr_search *s = &is->s;
1054         int error;
1055
1056         if (EXT4_I(inode)->i_extra_isize == 0)
1057                 return -ENOSPC;
1058         error = ext4_xattr_set_entry(i, s);
1059         if (error)
1060                 return error;
1061         header = IHDR(inode, ext4_raw_inode(&is->iloc));
1062         if (!IS_LAST_ENTRY(s->first)) {
1063                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1064                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
1065         } else {
1066                 header->h_magic = cpu_to_le32(0);
1067                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
1068         }
1069         return 0;
1070 }
1071
1072 /*
1073  * ext4_xattr_set_handle()
1074  *
1075  * Create, replace or remove an extended attribute for this inode.  Value
1076  * is NULL to remove an existing extended attribute, and non-NULL to
1077  * either replace an existing extended attribute, or create a new extended
1078  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
1079  * specify that an extended attribute must exist and must not exist
1080  * previous to the call, respectively.
1081  *
1082  * Returns 0, or a negative error number on failure.
1083  */
1084 int
1085 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
1086                       const char *name, const void *value, size_t value_len,
1087                       int flags)
1088 {
1089         struct ext4_xattr_info i = {
1090                 .name_index = name_index,
1091                 .name = name,
1092                 .value = value,
1093                 .value_len = value_len,
1094
1095         };
1096         struct ext4_xattr_ibody_find is = {
1097                 .s = { .not_found = -ENODATA, },
1098         };
1099         struct ext4_xattr_block_find bs = {
1100                 .s = { .not_found = -ENODATA, },
1101         };
1102         unsigned long no_expand;
1103         int error;
1104
1105         if (!name)
1106                 return -EINVAL;
1107         if (strlen(name) > 255)
1108                 return -ERANGE;
1109         down_write(&EXT4_I(inode)->xattr_sem);
1110         no_expand = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
1111         ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
1112
1113         error = ext4_reserve_inode_write(handle, inode, &is.iloc);
1114         if (error)
1115                 goto cleanup;
1116
1117         if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) {
1118                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
1119                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
1120                 ext4_clear_inode_state(inode, EXT4_STATE_NEW);
1121         }
1122
1123         error = ext4_xattr_ibody_find(inode, &i, &is);
1124         if (error)
1125                 goto cleanup;
1126         if (is.s.not_found)
1127                 error = ext4_xattr_block_find(inode, &i, &bs);
1128         if (error)
1129                 goto cleanup;
1130         if (is.s.not_found && bs.s.not_found) {
1131                 error = -ENODATA;
1132                 if (flags & XATTR_REPLACE)
1133                         goto cleanup;
1134                 error = 0;
1135                 if (!value)
1136                         goto cleanup;
1137         } else {
1138                 error = -EEXIST;
1139                 if (flags & XATTR_CREATE)
1140                         goto cleanup;
1141         }
1142         if (!value) {
1143                 if (!is.s.not_found)
1144                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1145                 else if (!bs.s.not_found)
1146                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1147         } else {
1148                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1149                 if (!error && !bs.s.not_found) {
1150                         i.value = NULL;
1151                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1152                 } else if (error == -ENOSPC) {
1153                         if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
1154                                 error = ext4_xattr_block_find(inode, &i, &bs);
1155                                 if (error)
1156                                         goto cleanup;
1157                         }
1158                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1159                         if (error)
1160                                 goto cleanup;
1161                         if (!is.s.not_found) {
1162                                 i.value = NULL;
1163                                 error = ext4_xattr_ibody_set(handle, inode, &i,
1164                                                              &is);
1165                         }
1166                 }
1167         }
1168         if (!error) {
1169                 ext4_xattr_update_super_block(handle, inode->i_sb);
1170                 inode->i_ctime = ext4_current_time(inode);
1171                 if (!value)
1172                         ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1173                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
1174                 /*
1175                  * The bh is consumed by ext4_mark_iloc_dirty, even with
1176                  * error != 0.
1177                  */
1178                 is.iloc.bh = NULL;
1179                 if (IS_SYNC(inode))
1180                         ext4_handle_sync(handle);
1181         }
1182
1183 cleanup:
1184         brelse(is.iloc.bh);
1185         brelse(bs.bh);
1186         if (no_expand == 0)
1187                 ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1188         up_write(&EXT4_I(inode)->xattr_sem);
1189         return error;
1190 }
1191
1192 /*
1193  * ext4_xattr_set()
1194  *
1195  * Like ext4_xattr_set_handle, but start from an inode. This extended
1196  * attribute modification is a filesystem transaction by itself.
1197  *
1198  * Returns 0, or a negative error number on failure.
1199  */
1200 int
1201 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
1202                const void *value, size_t value_len, int flags)
1203 {
1204         handle_t *handle;
1205         int error, retries = 0;
1206         int credits = ext4_jbd2_credits_xattr(inode);
1207
1208 retry:
1209         handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
1210         if (IS_ERR(handle)) {
1211                 error = PTR_ERR(handle);
1212         } else {
1213                 int error2;
1214
1215                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
1216                                               value, value_len, flags);
1217                 error2 = ext4_journal_stop(handle);
1218                 if (error == -ENOSPC &&
1219                     ext4_should_retry_alloc(inode->i_sb, &retries))
1220                         goto retry;
1221                 if (error == 0)
1222                         error = error2;
1223         }
1224
1225         return error;
1226 }
1227
1228 /*
1229  * Shift the EA entries in the inode to create space for the increased
1230  * i_extra_isize.
1231  */
1232 static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
1233                                      int value_offs_shift, void *to,
1234                                      void *from, size_t n, int blocksize)
1235 {
1236         struct ext4_xattr_entry *last = entry;
1237         int new_offs;
1238
1239         /* Adjust the value offsets of the entries */
1240         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1241                 if (!last->e_value_block && last->e_value_size) {
1242                         new_offs = le16_to_cpu(last->e_value_offs) +
1243                                                         value_offs_shift;
1244                         BUG_ON(new_offs + le32_to_cpu(last->e_value_size)
1245                                  > blocksize);
1246                         last->e_value_offs = cpu_to_le16(new_offs);
1247                 }
1248         }
1249         /* Shift the entries by n bytes */
1250         memmove(to, from, n);
1251 }
1252
1253 /*
1254  * Expand an inode by new_extra_isize bytes when EAs are present.
1255  * Returns 0 on success or negative error number on failure.
1256  */
1257 int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
1258                                struct ext4_inode *raw_inode, handle_t *handle)
1259 {
1260         struct ext4_xattr_ibody_header *header;
1261         struct ext4_xattr_entry *entry, *last, *first;
1262         struct buffer_head *bh = NULL;
1263         struct ext4_xattr_ibody_find *is = NULL;
1264         struct ext4_xattr_block_find *bs = NULL;
1265         char *buffer = NULL, *b_entry_name = NULL;
1266         size_t min_offs, free;
1267         int total_ino;
1268         void *base, *start, *end;
1269         int extra_isize = 0, error = 0, tried_min_extra_isize = 0;
1270         int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize);
1271
1272         down_write(&EXT4_I(inode)->xattr_sem);
1273 retry:
1274         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize) {
1275                 up_write(&EXT4_I(inode)->xattr_sem);
1276                 return 0;
1277         }
1278
1279         header = IHDR(inode, raw_inode);
1280         entry = IFIRST(header);
1281
1282         /*
1283          * Check if enough free space is available in the inode to shift the
1284          * entries ahead by new_extra_isize.
1285          */
1286
1287         base = start = entry;
1288         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
1289         min_offs = end - base;
1290         last = entry;
1291         total_ino = sizeof(struct ext4_xattr_ibody_header);
1292
1293         free = ext4_xattr_free_space(last, &min_offs, base, &total_ino);
1294         if (free >= new_extra_isize) {
1295                 entry = IFIRST(header);
1296                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize
1297                                 - new_extra_isize, (void *)raw_inode +
1298                                 EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
1299                                 (void *)header, total_ino,
1300                                 inode->i_sb->s_blocksize);
1301                 EXT4_I(inode)->i_extra_isize = new_extra_isize;
1302                 error = 0;
1303                 goto cleanup;
1304         }
1305
1306         /*
1307          * Enough free space isn't available in the inode, check if
1308          * EA block can hold new_extra_isize bytes.
1309          */
1310         if (EXT4_I(inode)->i_file_acl) {
1311                 bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1312                 error = -EIO;
1313                 if (!bh)
1314                         goto cleanup;
1315                 if (ext4_xattr_check_block(inode, bh)) {
1316                         EXT4_ERROR_INODE(inode, "bad block %llu",
1317                                          EXT4_I(inode)->i_file_acl);
1318                         error = -EIO;
1319                         goto cleanup;
1320                 }
1321                 base = BHDR(bh);
1322                 first = BFIRST(bh);
1323                 end = bh->b_data + bh->b_size;
1324                 min_offs = end - base;
1325                 free = ext4_xattr_free_space(first, &min_offs, base, NULL);
1326                 if (free < new_extra_isize) {
1327                         if (!tried_min_extra_isize && s_min_extra_isize) {
1328                                 tried_min_extra_isize++;
1329                                 new_extra_isize = s_min_extra_isize;
1330                                 brelse(bh);
1331                                 goto retry;
1332                         }
1333                         error = -1;
1334                         goto cleanup;
1335                 }
1336         } else {
1337                 free = inode->i_sb->s_blocksize;
1338         }
1339
1340         while (new_extra_isize > 0) {
1341                 size_t offs, size, entry_size;
1342                 struct ext4_xattr_entry *small_entry = NULL;
1343                 struct ext4_xattr_info i = {
1344                         .value = NULL,
1345                         .value_len = 0,
1346                 };
1347                 unsigned int total_size;  /* EA entry size + value size */
1348                 unsigned int shift_bytes; /* No. of bytes to shift EAs by? */
1349                 unsigned int min_total_size = ~0U;
1350
1351                 is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
1352                 bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
1353                 if (!is || !bs) {
1354                         error = -ENOMEM;
1355                         goto cleanup;
1356                 }
1357
1358                 is->s.not_found = -ENODATA;
1359                 bs->s.not_found = -ENODATA;
1360                 is->iloc.bh = NULL;
1361                 bs->bh = NULL;
1362
1363                 last = IFIRST(header);
1364                 /* Find the entry best suited to be pushed into EA block */
1365                 entry = NULL;
1366                 for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1367                         total_size =
1368                         EXT4_XATTR_SIZE(le32_to_cpu(last->e_value_size)) +
1369                                         EXT4_XATTR_LEN(last->e_name_len);
1370                         if (total_size <= free && total_size < min_total_size) {
1371                                 if (total_size < new_extra_isize) {
1372                                         small_entry = last;
1373                                 } else {
1374                                         entry = last;
1375                                         min_total_size = total_size;
1376                                 }
1377                         }
1378                 }
1379
1380                 if (entry == NULL) {
1381                         if (small_entry) {
1382                                 entry = small_entry;
1383                         } else {
1384                                 if (!tried_min_extra_isize &&
1385                                     s_min_extra_isize) {
1386                                         tried_min_extra_isize++;
1387                                         new_extra_isize = s_min_extra_isize;
1388                                         kfree(is); is = NULL;
1389                                         kfree(bs); bs = NULL;
1390                                         brelse(bh);
1391                                         goto retry;
1392                                 }
1393                                 error = -1;
1394                                 goto cleanup;
1395                         }
1396                 }
1397                 offs = le16_to_cpu(entry->e_value_offs);
1398                 size = le32_to_cpu(entry->e_value_size);
1399                 entry_size = EXT4_XATTR_LEN(entry->e_name_len);
1400                 i.name_index = entry->e_name_index,
1401                 buffer = kmalloc(EXT4_XATTR_SIZE(size), GFP_NOFS);
1402                 b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
1403                 if (!buffer || !b_entry_name) {
1404                         error = -ENOMEM;
1405                         goto cleanup;
1406                 }
1407                 /* Save the entry name and the entry value */
1408                 memcpy(buffer, (void *)IFIRST(header) + offs,
1409                        EXT4_XATTR_SIZE(size));
1410                 memcpy(b_entry_name, entry->e_name, entry->e_name_len);
1411                 b_entry_name[entry->e_name_len] = '\0';
1412                 i.name = b_entry_name;
1413
1414                 error = ext4_get_inode_loc(inode, &is->iloc);
1415                 if (error)
1416                         goto cleanup;
1417
1418                 error = ext4_xattr_ibody_find(inode, &i, is);
1419                 if (error)
1420                         goto cleanup;
1421
1422                 /* Remove the chosen entry from the inode */
1423                 error = ext4_xattr_ibody_set(handle, inode, &i, is);
1424                 if (error)
1425                         goto cleanup;
1426
1427                 entry = IFIRST(header);
1428                 if (entry_size + EXT4_XATTR_SIZE(size) >= new_extra_isize)
1429                         shift_bytes = new_extra_isize;
1430                 else
1431                         shift_bytes = entry_size + size;
1432                 /* Adjust the offsets and shift the remaining entries ahead */
1433                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize -
1434                         shift_bytes, (void *)raw_inode +
1435                         EXT4_GOOD_OLD_INODE_SIZE + extra_isize + shift_bytes,
1436                         (void *)header, total_ino - entry_size,
1437                         inode->i_sb->s_blocksize);
1438
1439                 extra_isize += shift_bytes;
1440                 new_extra_isize -= shift_bytes;
1441                 EXT4_I(inode)->i_extra_isize = extra_isize;
1442
1443                 i.name = b_entry_name;
1444                 i.value = buffer;
1445                 i.value_len = size;
1446                 error = ext4_xattr_block_find(inode, &i, bs);
1447                 if (error)
1448                         goto cleanup;
1449
1450                 /* Add entry which was removed from the inode into the block */
1451                 error = ext4_xattr_block_set(handle, inode, &i, bs);
1452                 if (error)
1453                         goto cleanup;
1454                 kfree(b_entry_name);
1455                 kfree(buffer);
1456                 b_entry_name = NULL;
1457                 buffer = NULL;
1458                 brelse(is->iloc.bh);
1459                 kfree(is);
1460                 kfree(bs);
1461         }
1462         brelse(bh);
1463         up_write(&EXT4_I(inode)->xattr_sem);
1464         return 0;
1465
1466 cleanup:
1467         kfree(b_entry_name);
1468         kfree(buffer);
1469         if (is)
1470                 brelse(is->iloc.bh);
1471         kfree(is);
1472         kfree(bs);
1473         brelse(bh);
1474         up_write(&EXT4_I(inode)->xattr_sem);
1475         return error;
1476 }
1477
1478
1479
1480 /*
1481  * ext4_xattr_delete_inode()
1482  *
1483  * Free extended attribute resources associated with this inode. This
1484  * is called immediately before an inode is freed. We have exclusive
1485  * access to the inode.
1486  */
1487 void
1488 ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)
1489 {
1490         struct buffer_head *bh = NULL;
1491
1492         if (!EXT4_I(inode)->i_file_acl)
1493                 goto cleanup;
1494         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1495         if (!bh) {
1496                 EXT4_ERROR_INODE(inode, "block %llu read error",
1497                                  EXT4_I(inode)->i_file_acl);
1498                 goto cleanup;
1499         }
1500         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
1501             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1502                 EXT4_ERROR_INODE(inode, "bad block %llu",
1503                                  EXT4_I(inode)->i_file_acl);
1504                 goto cleanup;
1505         }
1506         ext4_xattr_release_block(handle, inode, bh);
1507         EXT4_I(inode)->i_file_acl = 0;
1508
1509 cleanup:
1510         brelse(bh);
1511 }
1512
1513 /*
1514  * ext4_xattr_put_super()
1515  *
1516  * This is called when a file system is unmounted.
1517  */
1518 void
1519 ext4_xattr_put_super(struct super_block *sb)
1520 {
1521         mb_cache_shrink(sb->s_bdev);
1522 }
1523
1524 /*
1525  * ext4_xattr_cache_insert()
1526  *
1527  * Create a new entry in the extended attribute cache, and insert
1528  * it unless such an entry is already in the cache.
1529  *
1530  * Returns 0, or a negative error number on failure.
1531  */
1532 static void
1533 ext4_xattr_cache_insert(struct mb_cache *ext4_mb_cache, struct buffer_head *bh)
1534 {
1535         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1536         struct mb_cache_entry *ce;
1537         int error;
1538
1539         ce = mb_cache_entry_alloc(ext4_mb_cache, GFP_NOFS);
1540         if (!ce) {
1541                 ea_bdebug(bh, "out of memory");
1542                 return;
1543         }
1544         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
1545         if (error) {
1546                 mb_cache_entry_free(ce);
1547                 if (error == -EBUSY) {
1548                         ea_bdebug(bh, "already in cache");
1549                         error = 0;
1550                 }
1551         } else {
1552                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1553                 mb_cache_entry_release(ce);
1554         }
1555 }
1556
1557 /*
1558  * ext4_xattr_cmp()
1559  *
1560  * Compare two extended attribute blocks for equality.
1561  *
1562  * Returns 0 if the blocks are equal, 1 if they differ, and
1563  * a negative error number on errors.
1564  */
1565 static int
1566 ext4_xattr_cmp(struct ext4_xattr_header *header1,
1567                struct ext4_xattr_header *header2)
1568 {
1569         struct ext4_xattr_entry *entry1, *entry2;
1570
1571         entry1 = ENTRY(header1+1);
1572         entry2 = ENTRY(header2+1);
1573         while (!IS_LAST_ENTRY(entry1)) {
1574                 if (IS_LAST_ENTRY(entry2))
1575                         return 1;
1576                 if (entry1->e_hash != entry2->e_hash ||
1577                     entry1->e_name_index != entry2->e_name_index ||
1578                     entry1->e_name_len != entry2->e_name_len ||
1579                     entry1->e_value_size != entry2->e_value_size ||
1580                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1581                         return 1;
1582                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1583                         return -EIO;
1584                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1585                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1586                            le32_to_cpu(entry1->e_value_size)))
1587                         return 1;
1588
1589                 entry1 = EXT4_XATTR_NEXT(entry1);
1590                 entry2 = EXT4_XATTR_NEXT(entry2);
1591         }
1592         if (!IS_LAST_ENTRY(entry2))
1593                 return 1;
1594         return 0;
1595 }
1596
1597 /*
1598  * ext4_xattr_cache_find()
1599  *
1600  * Find an identical extended attribute block.
1601  *
1602  * Returns a pointer to the block found, or NULL if such a block was
1603  * not found or an error occurred.
1604  */
1605 static struct buffer_head *
1606 ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
1607                       struct mb_cache_entry **pce)
1608 {
1609         __u32 hash = le32_to_cpu(header->h_hash);
1610         struct mb_cache_entry *ce;
1611         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
1612
1613         if (!header->h_hash)
1614                 return NULL;  /* never share */
1615         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1616 again:
1617         ce = mb_cache_entry_find_first(ext4_mb_cache, inode->i_sb->s_bdev,
1618                                        hash);
1619         while (ce) {
1620                 struct buffer_head *bh;
1621
1622                 if (IS_ERR(ce)) {
1623                         if (PTR_ERR(ce) == -EAGAIN)
1624                                 goto again;
1625                         break;
1626                 }
1627                 bh = sb_bread(inode->i_sb, ce->e_block);
1628                 if (!bh) {
1629                         EXT4_ERROR_INODE(inode, "block %lu read error",
1630                                          (unsigned long) ce->e_block);
1631                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1632                                 EXT4_XATTR_REFCOUNT_MAX) {
1633                         ea_idebug(inode, "block %lu refcount %d>=%d",
1634                                   (unsigned long) ce->e_block,
1635                                   le32_to_cpu(BHDR(bh)->h_refcount),
1636                                           EXT4_XATTR_REFCOUNT_MAX);
1637                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
1638                         *pce = ce;
1639                         return bh;
1640                 }
1641                 brelse(bh);
1642                 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
1643         }
1644         return NULL;
1645 }
1646
1647 #define NAME_HASH_SHIFT 5
1648 #define VALUE_HASH_SHIFT 16
1649
1650 /*
1651  * ext4_xattr_hash_entry()
1652  *
1653  * Compute the hash of an extended attribute.
1654  */
1655 static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
1656                                          struct ext4_xattr_entry *entry)
1657 {
1658         __u32 hash = 0;
1659         char *name = entry->e_name;
1660         int n;
1661
1662         for (n = 0; n < entry->e_name_len; n++) {
1663                 hash = (hash << NAME_HASH_SHIFT) ^
1664                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1665                        *name++;
1666         }
1667
1668         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1669                 __le32 *value = (__le32 *)((char *)header +
1670                         le16_to_cpu(entry->e_value_offs));
1671                 for (n = (le32_to_cpu(entry->e_value_size) +
1672                      EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {
1673                         hash = (hash << VALUE_HASH_SHIFT) ^
1674                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1675                                le32_to_cpu(*value++);
1676                 }
1677         }
1678         entry->e_hash = cpu_to_le32(hash);
1679 }
1680
1681 #undef NAME_HASH_SHIFT
1682 #undef VALUE_HASH_SHIFT
1683
1684 #define BLOCK_HASH_SHIFT 16
1685
1686 /*
1687  * ext4_xattr_rehash()
1688  *
1689  * Re-compute the extended attribute hash value after an entry has changed.
1690  */
1691 static void ext4_xattr_rehash(struct ext4_xattr_header *header,
1692                               struct ext4_xattr_entry *entry)
1693 {
1694         struct ext4_xattr_entry *here;
1695         __u32 hash = 0;
1696
1697         ext4_xattr_hash_entry(header, entry);
1698         here = ENTRY(header+1);
1699         while (!IS_LAST_ENTRY(here)) {
1700                 if (!here->e_hash) {
1701                         /* Block is not shared if an entry's hash value == 0 */
1702                         hash = 0;
1703                         break;
1704                 }
1705                 hash = (hash << BLOCK_HASH_SHIFT) ^
1706                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1707                        le32_to_cpu(here->e_hash);
1708                 here = EXT4_XATTR_NEXT(here);
1709         }
1710         header->h_hash = cpu_to_le32(hash);
1711 }
1712
1713 #undef BLOCK_HASH_SHIFT
1714
1715 #define HASH_BUCKET_BITS        10
1716
1717 struct mb_cache *
1718 ext4_xattr_create_cache(char *name)
1719 {
1720         return mb_cache_create(name, HASH_BUCKET_BITS);
1721 }
1722
1723 void ext4_xattr_destroy_cache(struct mb_cache *cache)
1724 {
1725         if (cache)
1726                 mb_cache_destroy(cache);
1727 }
1728