kernel/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  * d_inode(dentry)->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 -EFSCORRUPTED;
 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 -EFSCORRUPTED;
 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 -EFSCORRUPTED;
 226         if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh)))
 227                 return -EFSBADCRC;
 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 -EFSCORRUPTED;
 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 -EFSCORRUPTED;
 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 = -EFSCORRUPTED;
 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 == -EFSCORRUPTED)
 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(handler, dentry, buffer,
 409                                                     rest, entry->e_name,
 410                                                     entry->e_name_len);
 411                         if (buffer) {
 412                                 if (size > rest)
 413                                         return -ERANGE;
 414                                 buffer += size;
 415                         }
 416                         rest -= size;
 417                 }
 418         }
 419         return buffer_size - rest;
 420 }
 421
 422 static int
 423 ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 424 {
 425         struct inode *inode = d_inode(dentry);
 426         struct buffer_head *bh = NULL;
 427         int error;
 428         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 429
 430         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 431                   buffer, (long)buffer_size);
 432
 433         error = 0;
 434         if (!EXT4_I(inode)->i_file_acl)
 435                 goto cleanup;
 436         ea_idebug(inode, "reading block %llu",
 437                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 438         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 439         error = -EIO;
 440         if (!bh)
 441                 goto cleanup;
 442         ea_bdebug(bh, "b_count=%d, refcount=%d",
 443                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 444         if (ext4_xattr_check_block(inode, bh)) {
 445                 EXT4_ERROR_INODE(inode, "bad block %llu",
 446                                  EXT4_I(inode)->i_file_acl);
 447                 error = -EFSCORRUPTED;
 448                 goto cleanup;
 449         }
 450         ext4_xattr_cache_insert(ext4_mb_cache, bh);
 451         error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
 452
 453 cleanup:
 454         brelse(bh);
 455
 456         return error;
 457 }
 458
 459 static int
 460 ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 461 {
 462         struct inode *inode = d_inode(dentry);
 463         struct ext4_xattr_ibody_header *header;
 464         struct ext4_inode *raw_inode;
 465         struct ext4_iloc iloc;
 466         void *end;
 467         int error;
 468
 469         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 470                 return 0;
 471         error = ext4_get_inode_loc(inode, &iloc);
 472         if (error)
 473                 return error;
 474         raw_inode = ext4_raw_inode(&iloc);
 475         header = IHDR(inode, raw_inode);
 476         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 477         error = ext4_xattr_check_names(IFIRST(header), end, IFIRST(header));
 478         if (error)
 479                 goto cleanup;
 480         error = ext4_xattr_list_entries(dentry, IFIRST(header),
 481                                         buffer, buffer_size);
 482
 483 cleanup:
 484         brelse(iloc.bh);
 485         return error;
 486 }
 487
 488 /*
 489  * ext4_xattr_list()
 490  *
 491  * Copy a list of attribute names into the buffer
 492  * provided, or compute the buffer size required.
 493  * Buffer is NULL to compute the size of the buffer required.
 494  *
 495  * Returns a negative error number on failure, or the number of bytes
 496  * used / required on success.
 497  */
 498 static int
 499 ext4_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 500 {
 501         int ret, ret2;
 502
 503         down_read(&EXT4_I(d_inode(dentry))->xattr_sem);
 504         ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size);
 505         if (ret < 0)
 506                 goto errout;
 507         if (buffer) {
 508                 buffer += ret;
 509                 buffer_size -= ret;
 510         }
 511         ret = ext4_xattr_block_list(dentry, buffer, buffer_size);
 512         if (ret < 0)
 513                 goto errout;
 514         ret += ret2;
 515 errout:
 516         up_read(&EXT4_I(d_inode(dentry))->xattr_sem);
 517         return ret;
 518 }
 519
 520 /*
 521  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 522  * not set, set it.
 523  */
 524 static void ext4_xattr_update_super_block(handle_t *handle,
 525                                           struct super_block *sb)
 526 {
 527         if (ext4_has_feature_xattr(sb))
 528                 return;
 529
 530         BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
 531         if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
 532                 ext4_set_feature_xattr(sb);
 533                 ext4_handle_dirty_super(handle, sb);
 534         }
 535 }
 536
 537 /*
 538  * Release the xattr block BH: If the reference count is > 1, decrement it;
 539  * otherwise free the block.
 540  */
 541 static void
 542 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
 543                          struct buffer_head *bh)
 544 {
 545         struct mb_cache_entry *ce = NULL;
 546         int error = 0;
 547         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 548
 549         ce = mb_cache_entry_get(ext4_mb_cache, bh->b_bdev, bh->b_blocknr);
 550         BUFFER_TRACE(bh, "get_write_access");
 551         error = ext4_journal_get_write_access(handle, bh);
 552         if (error)
 553                 goto out;
 554
 555         lock_buffer(bh);
 556         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
 557                 ea_bdebug(bh, "refcount now=0; freeing");
 558                 if (ce)
 559                         mb_cache_entry_free(ce);
 560                 get_bh(bh);
 561                 unlock_buffer(bh);
 562                 ext4_free_blocks(handle, inode, bh, 0, 1,
 563                                  EXT4_FREE_BLOCKS_METADATA |
 564                                  EXT4_FREE_BLOCKS_FORGET);
 565         } else {
 566                 le32_add_cpu(&BHDR(bh)->h_refcount, -1);
 567                 if (ce)
 568                         mb_cache_entry_release(ce);
 569                 /*
 570                  * Beware of this ugliness: Releasing of xattr block references
 571                  * from different inodes can race and so we have to protect
 572                  * from a race where someone else frees the block (and releases
 573                  * its journal_head) before we are done dirtying the buffer. In
 574                  * nojournal mode this race is harmless and we actually cannot
 575                  * call ext4_handle_dirty_xattr_block() with locked buffer as
 576                  * that function can call sync_dirty_buffer() so for that case
 577                  * we handle the dirtying after unlocking the buffer.
 578                  */
 579                 if (ext4_handle_valid(handle))
 580                         error = ext4_handle_dirty_xattr_block(handle, inode,
 581                                                               bh);
 582                 unlock_buffer(bh);
 583                 if (!ext4_handle_valid(handle))
 584                         error = ext4_handle_dirty_xattr_block(handle, inode,
 585                                                               bh);
 586                 if (IS_SYNC(inode))
 587                         ext4_handle_sync(handle);
 588                 dquot_free_block(inode, EXT4_C2B(EXT4_SB(inode->i_sb), 1));
 589                 ea_bdebug(bh, "refcount now=%d; releasing",
 590                           le32_to_cpu(BHDR(bh)->h_refcount));
 591         }
 592 out:
 593         ext4_std_error(inode->i_sb, error);
 594         return;
 595 }
 596
 597 /*
 598  * Find the available free space for EAs. This also returns the total number of
 599  * bytes used by EA entries.
 600  */
 601 static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
 602                                     size_t *min_offs, void *base, int *total)
 603 {
 604         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 605                 if (!last->e_value_block && last->e_value_size) {
 606                         size_t offs = le16_to_cpu(last->e_value_offs);
 607                         if (offs < *min_offs)
 608                                 *min_offs = offs;
 609                 }
 610                 if (total)
 611                         *total += EXT4_XATTR_LEN(last->e_name_len);
 612         }
 613         return (*min_offs - ((void *)last - base) - sizeof(__u32));
 614 }
 615
 616 static int
 617 ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
 618 {
 619         struct ext4_xattr_entry *last;
 620         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
 621
 622         /* Compute min_offs and last. */
 623         last = s->first;
 624         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 625                 if (!last->e_value_block && last->e_value_size) {
 626                         size_t offs = le16_to_cpu(last->e_value_offs);
 627                         if (offs < min_offs)
 628                                 min_offs = offs;
 629                 }
 630         }
 631         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
 632         if (!s->not_found) {
 633                 if (!s->here->e_value_block && s->here->e_value_size) {
 634                         size_t size = le32_to_cpu(s->here->e_value_size);
 635                         free += EXT4_XATTR_SIZE(size);
 636                 }
 637                 free += EXT4_XATTR_LEN(name_len);
 638         }
 639         if (i->value) {
 640                 if (free < EXT4_XATTR_LEN(name_len) +
 641                            EXT4_XATTR_SIZE(i->value_len))
 642                         return -ENOSPC;
 643         }
 644
 645         if (i->value && s->not_found) {
 646                 /* Insert the new name. */
 647                 size_t size = EXT4_XATTR_LEN(name_len);
 648                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
 649                 memmove((void *)s->here + size, s->here, rest);
 650                 memset(s->here, 0, size);
 651                 s->here->e_name_index = i->name_index;
 652                 s->here->e_name_len = name_len;
 653                 memcpy(s->here->e_name, i->name, name_len);
 654         } else {
 655                 if (!s->here->e_value_block && s->here->e_value_size) {
 656                         void *first_val = s->base + min_offs;
 657                         size_t offs = le16_to_cpu(s->here->e_value_offs);
 658                         void *val = s->base + offs;
 659                         size_t size = EXT4_XATTR_SIZE(
 660                                 le32_to_cpu(s->here->e_value_size));
 661
 662                         if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
 663                                 /* The old and the new value have the same
 664                                    size. Just replace. */
 665                                 s->here->e_value_size =
 666                                         cpu_to_le32(i->value_len);
 667                                 if (i->value == EXT4_ZERO_XATTR_VALUE) {
 668                                         memset(val, 0, size);
 669                                 } else {
 670                                         /* Clear pad bytes first. */
 671                                         memset(val + size - EXT4_XATTR_PAD, 0,
 672                                                EXT4_XATTR_PAD);
 673                                         memcpy(val, i->value, i->value_len);
 674                                 }
 675                                 return 0;
 676                         }
 677
 678                         /* Remove the old value. */
 679                         memmove(first_val + size, first_val, val - first_val);
 680                         memset(first_val, 0, size);
 681                         s->here->e_value_size = 0;
 682                         s->here->e_value_offs = 0;
 683                         min_offs += size;
 684
 685                         /* Adjust all value offsets. */
 686                         last = s->first;
 687                         while (!IS_LAST_ENTRY(last)) {
 688                                 size_t o = le16_to_cpu(last->e_value_offs);
 689                                 if (!last->e_value_block &&
 690                                     last->e_value_size && o < offs)
 691                                         last->e_value_offs =
 692                                                 cpu_to_le16(o + size);
 693                                 last = EXT4_XATTR_NEXT(last);
 694                         }
 695                 }
 696                 if (!i->value) {
 697                         /* Remove the old name. */
 698                         size_t size = EXT4_XATTR_LEN(name_len);
 699                         last = ENTRY((void *)last - size);
 700                         memmove(s->here, (void *)s->here + size,
 701                                 (void *)last - (void *)s->here + sizeof(__u32));
 702                         memset(last, 0, size);
 703                 }
 704         }
 705
 706         if (i->value) {
 707                 /* Insert the new value. */
 708                 s->here->e_value_size = cpu_to_le32(i->value_len);
 709                 if (i->value_len) {
 710                         size_t size = EXT4_XATTR_SIZE(i->value_len);
 711                         void *val = s->base + min_offs - size;
 712                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
 713                         if (i->value == EXT4_ZERO_XATTR_VALUE) {
 714                                 memset(val, 0, size);
 715                         } else {
 716                                 /* Clear the pad bytes first. */
 717                                 memset(val + size - EXT4_XATTR_PAD, 0,
 718                                        EXT4_XATTR_PAD);
 719                                 memcpy(val, i->value, i->value_len);
 720                         }
 721                 }
 722         }
 723         return 0;
 724 }
 725
 726 struct ext4_xattr_block_find {
 727         struct ext4_xattr_search s;
 728         struct buffer_head *bh;
 729 };
 730
 731 static int
 732 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
 733                       struct ext4_xattr_block_find *bs)
 734 {
 735         struct super_block *sb = inode->i_sb;
 736         int error;
 737
 738         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
 739                   i->name_index, i->name, i->value, (long)i->value_len);
 740
 741         if (EXT4_I(inode)->i_file_acl) {
 742                 /* The inode already has an extended attribute block. */
 743                 bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);
 744                 error = -EIO;
 745                 if (!bs->bh)
 746                         goto cleanup;
 747                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
 748                         atomic_read(&(bs->bh->b_count)),
 749                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
 750                 if (ext4_xattr_check_block(inode, bs->bh)) {
 751                         EXT4_ERROR_INODE(inode, "bad block %llu",
 752                                          EXT4_I(inode)->i_file_acl);
 753                         error = -EFSCORRUPTED;
 754                         goto cleanup;
 755                 }
 756                 /* Find the named attribute. */
 757                 bs->s.base = BHDR(bs->bh);
 758                 bs->s.first = BFIRST(bs->bh);
 759                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
 760                 bs->s.here = bs->s.first;
 761                 error = ext4_xattr_find_entry(&bs->s.here, i->name_index,
 762                                               i->name, bs->bh->b_size, 1);
 763                 if (error && error != -ENODATA)
 764                         goto cleanup;
 765                 bs->s.not_found = error;
 766         }
 767         error = 0;
 768
 769 cleanup:
 770         return error;
 771 }
 772
 773 static int
 774 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
 775                      struct ext4_xattr_info *i,
 776                      struct ext4_xattr_block_find *bs)
 777 {
 778         struct super_block *sb = inode->i_sb;
 779         struct buffer_head *new_bh = NULL;
 780         struct ext4_xattr_search *s = &bs->s;
 781         struct mb_cache_entry *ce = NULL;
 782         int error = 0;
 783         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 784
 785 #define header(x) ((struct ext4_xattr_header *)(x))
 786
 787         if (i->value && i->value_len > sb->s_blocksize)
 788                 return -ENOSPC;
 789         if (s->base) {
 790                 ce = mb_cache_entry_get(ext4_mb_cache, bs->bh->b_bdev,
 791                                         bs->bh->b_blocknr);
 792                 BUFFER_TRACE(bs->bh, "get_write_access");
 793                 error = ext4_journal_get_write_access(handle, bs->bh);
 794                 if (error)
 795                         goto cleanup;
 796                 lock_buffer(bs->bh);
 797
 798                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 799                         if (ce) {
 800                                 mb_cache_entry_free(ce);
 801                                 ce = NULL;
 802                         }
 803                         ea_bdebug(bs->bh, "modifying in-place");
 804                         error = ext4_xattr_set_entry(i, s);
 805                         if (!error) {
 806                                 if (!IS_LAST_ENTRY(s->first))
 807                                         ext4_xattr_rehash(header(s->base),
 808                                                           s->here);
 809                                 ext4_xattr_cache_insert(ext4_mb_cache,
 810                                         bs->bh);
 811                         }
 812                         unlock_buffer(bs->bh);
 813                         if (error == -EFSCORRUPTED)
 814                                 goto bad_block;
 815                         if (!error)
 816                                 error = ext4_handle_dirty_xattr_block(handle,
 817                                                                       inode,
 818                                                                       bs->bh);
 819                         if (error)
 820                                 goto cleanup;
 821                         goto inserted;
 822                 } else {
 823                         int offset = (char *)s->here - bs->bh->b_data;
 824
 825                         unlock_buffer(bs->bh);
 826                         if (ce) {
 827                                 mb_cache_entry_release(ce);
 828                                 ce = NULL;
 829                         }
 830                         ea_bdebug(bs->bh, "cloning");
 831                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
 832                         error = -ENOMEM;
 833                         if (s->base == NULL)
 834                                 goto cleanup;
 835                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 836                         s->first = ENTRY(header(s->base)+1);
 837                         header(s->base)->h_refcount = cpu_to_le32(1);
 838                         s->here = ENTRY(s->base + offset);
 839                         s->end = s->base + bs->bh->b_size;
 840                 }
 841         } else {
 842                 /* Allocate a buffer where we construct the new block. */
 843                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
 844                 /* assert(header == s->base) */
 845                 error = -ENOMEM;
 846                 if (s->base == NULL)
 847                         goto cleanup;
 848                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
 849                 header(s->base)->h_blocks = cpu_to_le32(1);
 850                 header(s->base)->h_refcount = cpu_to_le32(1);
 851                 s->first = ENTRY(header(s->base)+1);
 852                 s->here = ENTRY(header(s->base)+1);
 853                 s->end = s->base + sb->s_blocksize;
 854         }
 855
 856         error = ext4_xattr_set_entry(i, s);
 857         if (error == -EFSCORRUPTED)
 858                 goto bad_block;
 859         if (error)
 860                 goto cleanup;
 861         if (!IS_LAST_ENTRY(s->first))
 862                 ext4_xattr_rehash(header(s->base), s->here);
 863
 864 inserted:
 865         if (!IS_LAST_ENTRY(s->first)) {
 866                 new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);
 867                 if (new_bh) {
 868                         /* We found an identical block in the cache. */
 869                         if (new_bh == bs->bh)
 870                                 ea_bdebug(new_bh, "keeping");
 871                         else {
 872                                 /* The old block is released after updating
 873                                    the inode. */
 874                                 error = dquot_alloc_block(inode,
 875                                                 EXT4_C2B(EXT4_SB(sb), 1));
 876                                 if (error)
 877                                         goto cleanup;
 878                                 BUFFER_TRACE(new_bh, "get_write_access");
 879                                 error = ext4_journal_get_write_access(handle,
 880                                                                       new_bh);
 881                                 if (error)
 882                                         goto cleanup_dquot;
 883                                 lock_buffer(new_bh);
 884                                 le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
 885                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
 886                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 887                                 unlock_buffer(new_bh);
 888                                 error = ext4_handle_dirty_xattr_block(handle,
 889                                                                       inode,
 890                                                                       new_bh);
 891                                 if (error)
 892                                         goto cleanup_dquot;
 893                         }
 894                         mb_cache_entry_release(ce);
 895                         ce = NULL;
 896                 } else if (bs->bh && s->base == bs->bh->b_data) {
 897                         /* We were modifying this block in-place. */
 898                         ea_bdebug(bs->bh, "keeping this block");
 899                         new_bh = bs->bh;
 900                         get_bh(new_bh);
 901                 } else {
 902                         /* We need to allocate a new block */
 903                         ext4_fsblk_t goal, block;
 904
 905                         goal = ext4_group_first_block_no(sb,
 906                                                 EXT4_I(inode)->i_block_group);
 907
 908                         /* non-extent files can't have physical blocks past 2^32 */
 909                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 910                                 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
 911
 912                         block = ext4_new_meta_blocks(handle, inode, goal, 0,
 913                                                      NULL, &error);
 914                         if (error)
 915                                 goto cleanup;
 916
 917                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 918                                 BUG_ON(block > EXT4_MAX_BLOCK_FILE_PHYS);
 919
 920                         ea_idebug(inode, "creating block %llu",
 921                                   (unsigned long long)block);
 922
 923                         new_bh = sb_getblk(sb, block);
 924                         if (unlikely(!new_bh)) {
 925                                 error = -ENOMEM;
 926 getblk_failed:
 927                                 ext4_free_blocks(handle, inode, NULL, block, 1,
 928                                                  EXT4_FREE_BLOCKS_METADATA);
 929                                 goto cleanup;
 930                         }
 931                         lock_buffer(new_bh);
 932                         error = ext4_journal_get_create_access(handle, new_bh);
 933                         if (error) {
 934                                 unlock_buffer(new_bh);
 935                                 error = -EIO;
 936                                 goto getblk_failed;
 937                         }
 938                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
 939                         set_buffer_uptodate(new_bh);
 940                         unlock_buffer(new_bh);
 941                         ext4_xattr_cache_insert(ext4_mb_cache, new_bh);
 942                         error = ext4_handle_dirty_xattr_block(handle,
 943                                                               inode, new_bh);
 944                         if (error)
 945                                 goto cleanup;
 946                 }
 947         }
 948
 949         /* Update the inode. */
 950         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
 951
 952         /* Drop the previous xattr block. */
 953         if (bs->bh && bs->bh != new_bh)
 954                 ext4_xattr_release_block(handle, inode, bs->bh);
 955         error = 0;
 956
 957 cleanup:
 958         if (ce)
 959                 mb_cache_entry_release(ce);
 960         brelse(new_bh);
 961         if (!(bs->bh && s->base == bs->bh->b_data))
 962                 kfree(s->base);
 963
 964         return error;
 965
 966 cleanup_dquot:
 967         dquot_free_block(inode, EXT4_C2B(EXT4_SB(sb), 1));
 968         goto cleanup;
 969
 970 bad_block:
 971         EXT4_ERROR_INODE(inode, "bad block %llu",
 972                          EXT4_I(inode)->i_file_acl);
 973         goto cleanup;
 974
 975 #undef header
 976 }
 977
 978 int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
 979                           struct ext4_xattr_ibody_find *is)
 980 {
 981         struct ext4_xattr_ibody_header *header;
 982         struct ext4_inode *raw_inode;
 983         int error;
 984
 985         if (EXT4_I(inode)->i_extra_isize == 0)
 986                 return 0;
 987         raw_inode = ext4_raw_inode(&is->iloc);
 988         header = IHDR(inode, raw_inode);
 989         is->s.base = is->s.first = IFIRST(header);
 990         is->s.here = is->s.first;
 991         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 992         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
 993                 error = ext4_xattr_check_names(IFIRST(header), is->s.end,
 994                                                IFIRST(header));
 995                 if (error)
 996                         return error;
 997                 /* Find the named attribute. */
 998                 error = ext4_xattr_find_entry(&is->s.here, i->name_index,
 999                                               i->name, is->s.end -
1000                                               (void *)is->s.base, 0);
1001                 if (error && error != -ENODATA)
1002                         return error;
1003                 is->s.not_found = error;
1004         }
1005         return 0;
1006 }
1007
1008 int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode,
1009                                 struct ext4_xattr_info *i,
1010                                 struct ext4_xattr_ibody_find *is)
1011 {
1012         struct ext4_xattr_ibody_header *header;
1013         struct ext4_xattr_search *s = &is->s;
1014         int error;
1015
1016         if (EXT4_I(inode)->i_extra_isize == 0)
1017                 return -ENOSPC;
1018         error = ext4_xattr_set_entry(i, s);
1019         if (error) {
1020                 if (error == -ENOSPC &&
1021                     ext4_has_inline_data(inode)) {
1022                         error = ext4_try_to_evict_inline_data(handle, inode,
1023                                         EXT4_XATTR_LEN(strlen(i->name) +
1024                                         EXT4_XATTR_SIZE(i->value_len)));
1025                         if (error)
1026                                 return error;
1027                         error = ext4_xattr_ibody_find(inode, i, is);
1028                         if (error)
1029                                 return error;
1030                         error = ext4_xattr_set_entry(i, s);
1031                 }
1032                 if (error)
1033                         return error;
1034         }
1035         header = IHDR(inode, ext4_raw_inode(&is->iloc));
1036         if (!IS_LAST_ENTRY(s->first)) {
1037                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1038                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
1039         } else {
1040                 header->h_magic = cpu_to_le32(0);
1041                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
1042         }
1043         return 0;
1044 }
1045
1046 static int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
1047                                 struct ext4_xattr_info *i,
1048                                 struct ext4_xattr_ibody_find *is)
1049 {
1050         struct ext4_xattr_ibody_header *header;
1051         struct ext4_xattr_search *s = &is->s;
1052         int error;
1053
1054         if (EXT4_I(inode)->i_extra_isize == 0)
1055                 return -ENOSPC;
1056         error = ext4_xattr_set_entry(i, s);
1057         if (error)
1058                 return error;
1059         header = IHDR(inode, ext4_raw_inode(&is->iloc));
1060         if (!IS_LAST_ENTRY(s->first)) {
1061                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1062                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
1063         } else {
1064                 header->h_magic = cpu_to_le32(0);
1065                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
1066         }
1067         return 0;
1068 }
1069
1070 /*
1071  * ext4_xattr_set_handle()
1072  *
1073  * Create, replace or remove an extended attribute for this inode.  Value
1074  * is NULL to remove an existing extended attribute, and non-NULL to
1075  * either replace an existing extended attribute, or create a new extended
1076  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
1077  * specify that an extended attribute must exist and must not exist
1078  * previous to the call, respectively.
1079  *
1080  * Returns 0, or a negative error number on failure.
1081  */
1082 int
1083 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
1084                       const char *name, const void *value, size_t value_len,
1085                       int flags)
1086 {
1087         struct ext4_xattr_info i = {
1088                 .name_index = name_index,
1089                 .name = name,
1090                 .value = value,
1091                 .value_len = value_len,
1092
1093         };
1094         struct ext4_xattr_ibody_find is = {
1095                 .s = { .not_found = -ENODATA, },
1096         };
1097         struct ext4_xattr_block_find bs = {
1098                 .s = { .not_found = -ENODATA, },
1099         };
1100         unsigned long no_expand;
1101         int error;
1102
1103         if (!name)
1104                 return -EINVAL;
1105         if (strlen(name) > 255)
1106                 return -ERANGE;
1107         down_write(&EXT4_I(inode)->xattr_sem);
1108         no_expand = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
1109         ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
1110
1111         error = ext4_reserve_inode_write(handle, inode, &is.iloc);
1112         if (error)
1113                 goto cleanup;
1114
1115         if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) {
1116                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
1117                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
1118                 ext4_clear_inode_state(inode, EXT4_STATE_NEW);
1119         }
1120
1121         error = ext4_xattr_ibody_find(inode, &i, &is);
1122         if (error)
1123                 goto cleanup;
1124         if (is.s.not_found)
1125                 error = ext4_xattr_block_find(inode, &i, &bs);
1126         if (error)
1127                 goto cleanup;
1128         if (is.s.not_found && bs.s.not_found) {
1129                 error = -ENODATA;
1130                 if (flags & XATTR_REPLACE)
1131                         goto cleanup;
1132                 error = 0;
1133                 if (!value)
1134                         goto cleanup;
1135         } else {
1136                 error = -EEXIST;
1137                 if (flags & XATTR_CREATE)
1138                         goto cleanup;
1139         }
1140         if (!value) {
1141                 if (!is.s.not_found)
1142                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1143                 else if (!bs.s.not_found)
1144                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1145         } else {
1146                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1147                 if (!error && !bs.s.not_found) {
1148                         i.value = NULL;
1149                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1150                 } else if (error == -ENOSPC) {
1151                         if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
1152                                 error = ext4_xattr_block_find(inode, &i, &bs);
1153                                 if (error)
1154                                         goto cleanup;
1155                         }
1156                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1157                         if (error)
1158                                 goto cleanup;
1159                         if (!is.s.not_found) {
1160                                 i.value = NULL;
1161                                 error = ext4_xattr_ibody_set(handle, inode, &i,
1162                                                              &is);
1163                         }
1164                 }
1165         }
1166         if (!error) {
1167                 ext4_xattr_update_super_block(handle, inode->i_sb);
1168                 inode->i_ctime = ext4_current_time(inode);
1169                 if (!value)
1170                         ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1171                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
1172                 /*
1173                  * The bh is consumed by ext4_mark_iloc_dirty, even with
1174                  * error != 0.
1175                  */
1176                 is.iloc.bh = NULL;
1177                 if (IS_SYNC(inode))
1178                         ext4_handle_sync(handle);
1179         }
1180
1181 cleanup:
1182         brelse(is.iloc.bh);
1183         brelse(bs.bh);
1184         if (no_expand == 0)
1185                 ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1186         up_write(&EXT4_I(inode)->xattr_sem);
1187         return error;
1188 }
1189
1190 /*
1191  * ext4_xattr_set()
1192  *
1193  * Like ext4_xattr_set_handle, but start from an inode. This extended
1194  * attribute modification is a filesystem transaction by itself.
1195  *
1196  * Returns 0, or a negative error number on failure.
1197  */
1198 int
1199 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
1200                const void *value, size_t value_len, int flags)
1201 {
1202         handle_t *handle;
1203         int error, retries = 0;
1204         int credits = ext4_jbd2_credits_xattr(inode);
1205
1206 retry:
1207         handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
1208         if (IS_ERR(handle)) {
1209                 error = PTR_ERR(handle);
1210         } else {
1211                 int error2;
1212
1213                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
1214                                               value, value_len, flags);
1215                 error2 = ext4_journal_stop(handle);
1216                 if (error == -ENOSPC &&
1217                     ext4_should_retry_alloc(inode->i_sb, &retries))
1218                         goto retry;
1219                 if (error == 0)
1220                         error = error2;
1221         }
1222
1223         return error;
1224 }
1225
1226 /*
1227  * Shift the EA entries in the inode to create space for the increased
1228  * i_extra_isize.
1229  */
1230 static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
1231                                      int value_offs_shift, void *to,
1232                                      void *from, size_t n, int blocksize)
1233 {
1234         struct ext4_xattr_entry *last = entry;
1235         int new_offs;
1236
1237         /* Adjust the value offsets of the entries */
1238         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1239                 if (!last->e_value_block && last->e_value_size) {
1240                         new_offs = le16_to_cpu(last->e_value_offs) +
1241                                                         value_offs_shift;
1242                         BUG_ON(new_offs + le32_to_cpu(last->e_value_size)
1243                                  > blocksize);
1244                         last->e_value_offs = cpu_to_le16(new_offs);
1245                 }
1246         }
1247         /* Shift the entries by n bytes */
1248         memmove(to, from, n);
1249 }
1250
1251 /*
1252  * Expand an inode by new_extra_isize bytes when EAs are present.
1253  * Returns 0 on success or negative error number on failure.
1254  */
1255 int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
1256                                struct ext4_inode *raw_inode, handle_t *handle)
1257 {
1258         struct ext4_xattr_ibody_header *header;
1259         struct ext4_xattr_entry *entry, *last, *first;
1260         struct buffer_head *bh = NULL;
1261         struct ext4_xattr_ibody_find *is = NULL;
1262         struct ext4_xattr_block_find *bs = NULL;
1263         char *buffer = NULL, *b_entry_name = NULL;
1264         size_t min_offs, free;
1265         int total_ino;
1266         void *base, *start, *end;
1267         int extra_isize = 0, error = 0, tried_min_extra_isize = 0;
1268         int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize);
1269
1270         down_write(&EXT4_I(inode)->xattr_sem);
1271 retry:
1272         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize) {
1273                 up_write(&EXT4_I(inode)->xattr_sem);
1274                 return 0;
1275         }
1276
1277         header = IHDR(inode, raw_inode);
1278         entry = IFIRST(header);
1279
1280         /*
1281          * Check if enough free space is available in the inode to shift the
1282          * entries ahead by new_extra_isize.
1283          */
1284
1285         base = start = entry;
1286         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
1287         min_offs = end - base;
1288         last = entry;
1289         total_ino = sizeof(struct ext4_xattr_ibody_header);
1290
1291         free = ext4_xattr_free_space(last, &min_offs, base, &total_ino);
1292         if (free >= new_extra_isize) {
1293                 entry = IFIRST(header);
1294                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize
1295                                 - new_extra_isize, (void *)raw_inode +
1296                                 EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
1297                                 (void *)header, total_ino,
1298                                 inode->i_sb->s_blocksize);
1299                 EXT4_I(inode)->i_extra_isize = new_extra_isize;
1300                 error = 0;
1301                 goto cleanup;
1302         }
1303
1304         /*
1305          * Enough free space isn't available in the inode, check if
1306          * EA block can hold new_extra_isize bytes.
1307          */
1308         if (EXT4_I(inode)->i_file_acl) {
1309                 bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1310                 error = -EIO;
1311                 if (!bh)
1312                         goto cleanup;
1313                 if (ext4_xattr_check_block(inode, bh)) {
1314                         EXT4_ERROR_INODE(inode, "bad block %llu",
1315                                          EXT4_I(inode)->i_file_acl);
1316                         error = -EFSCORRUPTED;
1317                         goto cleanup;
1318                 }
1319                 base = BHDR(bh);
1320                 first = BFIRST(bh);
1321                 end = bh->b_data + bh->b_size;
1322                 min_offs = end - base;
1323                 free = ext4_xattr_free_space(first, &min_offs, base, NULL);
1324                 if (free < new_extra_isize) {
1325                         if (!tried_min_extra_isize && s_min_extra_isize) {
1326                                 tried_min_extra_isize++;
1327                                 new_extra_isize = s_min_extra_isize;
1328                                 brelse(bh);
1329                                 goto retry;
1330                         }
1331                         error = -1;
1332                         goto cleanup;
1333                 }
1334         } else {
1335                 free = inode->i_sb->s_blocksize;
1336         }
1337
1338         while (new_extra_isize > 0) {
1339                 size_t offs, size, entry_size;
1340                 struct ext4_xattr_entry *small_entry = NULL;
1341                 struct ext4_xattr_info i = {
1342                         .value = NULL,
1343                         .value_len = 0,
1344                 };
1345                 unsigned int total_size;  /* EA entry size + value size */
1346                 unsigned int shift_bytes; /* No. of bytes to shift EAs by? */
1347                 unsigned int min_total_size = ~0U;
1348
1349                 is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
1350                 bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
1351                 if (!is || !bs) {
1352                         error = -ENOMEM;
1353                         goto cleanup;
1354                 }
1355
1356                 is->s.not_found = -ENODATA;
1357                 bs->s.not_found = -ENODATA;
1358                 is->iloc.bh = NULL;
1359                 bs->bh = NULL;
1360
1361                 last = IFIRST(header);
1362                 /* Find the entry best suited to be pushed into EA block */
1363                 entry = NULL;
1364                 for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1365                         total_size =
1366                         EXT4_XATTR_SIZE(le32_to_cpu(last->e_value_size)) +
1367                                         EXT4_XATTR_LEN(last->e_name_len);
1368                         if (total_size <= free && total_size < min_total_size) {
1369                                 if (total_size < new_extra_isize) {
1370                                         small_entry = last;
1371                                 } else {
1372                                         entry = last;
1373                                         min_total_size = total_size;
1374                                 }
1375                         }
1376                 }
1377
1378                 if (entry == NULL) {
1379                         if (small_entry) {
1380                                 entry = small_entry;
1381                         } else {
1382                                 if (!tried_min_extra_isize &&
1383                                     s_min_extra_isize) {
1384                                         tried_min_extra_isize++;
1385                                         new_extra_isize = s_min_extra_isize;
1386                                         kfree(is); is = NULL;
1387                                         kfree(bs); bs = NULL;
1388                                         brelse(bh);
1389                                         goto retry;
1390                                 }
1391                                 error = -1;
1392                                 goto cleanup;
1393                         }
1394                 }
1395                 offs = le16_to_cpu(entry->e_value_offs);
1396                 size = le32_to_cpu(entry->e_value_size);
1397                 entry_size = EXT4_XATTR_LEN(entry->e_name_len);
1398                 i.name_index = entry->e_name_index,
1399                 buffer = kmalloc(EXT4_XATTR_SIZE(size), GFP_NOFS);
1400                 b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
1401                 if (!buffer || !b_entry_name) {
1402                         error = -ENOMEM;
1403                         goto cleanup;
1404                 }
1405                 /* Save the entry name and the entry value */
1406                 memcpy(buffer, (void *)IFIRST(header) + offs,
1407                        EXT4_XATTR_SIZE(size));
1408                 memcpy(b_entry_name, entry->e_name, entry->e_name_len);
1409                 b_entry_name[entry->e_name_len] = '\0';
1410                 i.name = b_entry_name;
1411
1412                 error = ext4_get_inode_loc(inode, &is->iloc);
1413                 if (error)
1414                         goto cleanup;
1415
1416                 error = ext4_xattr_ibody_find(inode, &i, is);
1417                 if (error)
1418                         goto cleanup;
1419
1420                 /* Remove the chosen entry from the inode */
1421                 error = ext4_xattr_ibody_set(handle, inode, &i, is);
1422                 if (error)
1423                         goto cleanup;
1424
1425                 entry = IFIRST(header);
1426                 if (entry_size + EXT4_XATTR_SIZE(size) >= new_extra_isize)
1427                         shift_bytes = new_extra_isize;
1428                 else
1429                         shift_bytes = entry_size + size;
1430                 /* Adjust the offsets and shift the remaining entries ahead */
1431                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize -
1432                         shift_bytes, (void *)raw_inode +
1433                         EXT4_GOOD_OLD_INODE_SIZE + extra_isize + shift_bytes,
1434                         (void *)header, total_ino - entry_size,
1435                         inode->i_sb->s_blocksize);
1436
1437                 extra_isize += shift_bytes;
1438                 new_extra_isize -= shift_bytes;
1439                 EXT4_I(inode)->i_extra_isize = extra_isize;
1440
1441                 i.name = b_entry_name;
1442                 i.value = buffer;
1443                 i.value_len = size;
1444                 error = ext4_xattr_block_find(inode, &i, bs);
1445                 if (error)
1446                         goto cleanup;
1447
1448                 /* Add entry which was removed from the inode into the block */
1449                 error = ext4_xattr_block_set(handle, inode, &i, bs);
1450                 if (error)
1451                         goto cleanup;
1452                 kfree(b_entry_name);
1453                 kfree(buffer);
1454                 b_entry_name = NULL;
1455                 buffer = NULL;
1456                 brelse(is->iloc.bh);
1457                 kfree(is);
1458                 kfree(bs);
1459         }
1460         brelse(bh);
1461         up_write(&EXT4_I(inode)->xattr_sem);
1462         return 0;
1463
1464 cleanup:
1465         kfree(b_entry_name);
1466         kfree(buffer);
1467         if (is)
1468                 brelse(is->iloc.bh);
1469         kfree(is);
1470         kfree(bs);
1471         brelse(bh);
1472         up_write(&EXT4_I(inode)->xattr_sem);
1473         return error;
1474 }
1475
1476
1477
1478 /*
1479  * ext4_xattr_delete_inode()
1480  *
1481  * Free extended attribute resources associated with this inode. This
1482  * is called immediately before an inode is freed. We have exclusive
1483  * access to the inode.
1484  */
1485 void
1486 ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)
1487 {
1488         struct buffer_head *bh = NULL;
1489
1490         if (!EXT4_I(inode)->i_file_acl)
1491                 goto cleanup;
1492         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1493         if (!bh) {
1494                 EXT4_ERROR_INODE(inode, "block %llu read error",
1495                                  EXT4_I(inode)->i_file_acl);
1496                 goto cleanup;
1497         }
1498         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
1499             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1500                 EXT4_ERROR_INODE(inode, "bad block %llu",
1501                                  EXT4_I(inode)->i_file_acl);
1502                 goto cleanup;
1503         }
1504         ext4_xattr_release_block(handle, inode, bh);
1505         EXT4_I(inode)->i_file_acl = 0;
1506
1507 cleanup:
1508         brelse(bh);
1509 }
1510
1511 /*
1512  * ext4_xattr_put_super()
1513  *
1514  * This is called when a file system is unmounted.
1515  */
1516 void
1517 ext4_xattr_put_super(struct super_block *sb)
1518 {
1519         mb_cache_shrink(sb->s_bdev);
1520 }
1521
1522 /*
1523  * ext4_xattr_cache_insert()
1524  *
1525  * Create a new entry in the extended attribute cache, and insert
1526  * it unless such an entry is already in the cache.
1527  *
1528  * Returns 0, or a negative error number on failure.
1529  */
1530 static void
1531 ext4_xattr_cache_insert(struct mb_cache *ext4_mb_cache, struct buffer_head *bh)
1532 {
1533         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1534         struct mb_cache_entry *ce;
1535         int error;
1536
1537         ce = mb_cache_entry_alloc(ext4_mb_cache, GFP_NOFS);
1538         if (!ce) {
1539                 ea_bdebug(bh, "out of memory");
1540                 return;
1541         }
1542         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
1543         if (error) {
1544                 mb_cache_entry_free(ce);
1545                 if (error == -EBUSY) {
1546                         ea_bdebug(bh, "already in cache");
1547                         error = 0;
1548                 }
1549         } else {
1550                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1551                 mb_cache_entry_release(ce);
1552         }
1553 }
1554
1555 /*
1556  * ext4_xattr_cmp()
1557  *
1558  * Compare two extended attribute blocks for equality.
1559  *
1560  * Returns 0 if the blocks are equal, 1 if they differ, and
1561  * a negative error number on errors.
1562  */
1563 static int
1564 ext4_xattr_cmp(struct ext4_xattr_header *header1,
1565                struct ext4_xattr_header *header2)
1566 {
1567         struct ext4_xattr_entry *entry1, *entry2;
1568
1569         entry1 = ENTRY(header1+1);
1570         entry2 = ENTRY(header2+1);
1571         while (!IS_LAST_ENTRY(entry1)) {
1572                 if (IS_LAST_ENTRY(entry2))
1573                         return 1;
1574                 if (entry1->e_hash != entry2->e_hash ||
1575                     entry1->e_name_index != entry2->e_name_index ||
1576                     entry1->e_name_len != entry2->e_name_len ||
1577                     entry1->e_value_size != entry2->e_value_size ||
1578                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1579                         return 1;
1580                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1581                         return -EFSCORRUPTED;
1582                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1583                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1584                            le32_to_cpu(entry1->e_value_size)))
1585                         return 1;
1586
1587                 entry1 = EXT4_XATTR_NEXT(entry1);
1588                 entry2 = EXT4_XATTR_NEXT(entry2);
1589         }
1590         if (!IS_LAST_ENTRY(entry2))
1591                 return 1;
1592         return 0;
1593 }
1594
1595 /*
1596  * ext4_xattr_cache_find()
1597  *
1598  * Find an identical extended attribute block.
1599  *
1600  * Returns a pointer to the block found, or NULL if such a block was
1601  * not found or an error occurred.
1602  */
1603 static struct buffer_head *
1604 ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
1605                       struct mb_cache_entry **pce)
1606 {
1607         __u32 hash = le32_to_cpu(header->h_hash);
1608         struct mb_cache_entry *ce;
1609         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
1610
1611         if (!header->h_hash)
1612                 return NULL;  /* never share */
1613         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1614 again:
1615         ce = mb_cache_entry_find_first(ext4_mb_cache, inode->i_sb->s_bdev,
1616                                        hash);
1617         while (ce) {
1618                 struct buffer_head *bh;
1619
1620                 if (IS_ERR(ce)) {
1621                         if (PTR_ERR(ce) == -EAGAIN)
1622                                 goto again;
1623                         break;
1624                 }
1625                 bh = sb_bread(inode->i_sb, ce->e_block);
1626                 if (!bh) {
1627                         EXT4_ERROR_INODE(inode, "block %lu read error",
1628                                          (unsigned long) ce->e_block);
1629                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1630                                 EXT4_XATTR_REFCOUNT_MAX) {
1631                         ea_idebug(inode, "block %lu refcount %d>=%d",
1632                                   (unsigned long) ce->e_block,
1633                                   le32_to_cpu(BHDR(bh)->h_refcount),
1634                                           EXT4_XATTR_REFCOUNT_MAX);
1635                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
1636                         *pce = ce;
1637                         return bh;
1638                 }
1639                 brelse(bh);
1640                 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
1641         }
1642         return NULL;
1643 }
1644
1645 #define NAME_HASH_SHIFT 5
1646 #define VALUE_HASH_SHIFT 16
1647
1648 /*
1649  * ext4_xattr_hash_entry()
1650  *
1651  * Compute the hash of an extended attribute.
1652  */
1653 static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
1654                                          struct ext4_xattr_entry *entry)
1655 {
1656         __u32 hash = 0;
1657         char *name = entry->e_name;
1658         int n;
1659
1660         for (n = 0; n < entry->e_name_len; n++) {
1661                 hash = (hash << NAME_HASH_SHIFT) ^
1662                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1663                        *name++;
1664         }
1665
1666         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1667                 __le32 *value = (__le32 *)((char *)header +
1668                         le16_to_cpu(entry->e_value_offs));
1669                 for (n = (le32_to_cpu(entry->e_value_size) +
1670                      EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {
1671                         hash = (hash << VALUE_HASH_SHIFT) ^
1672                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1673                                le32_to_cpu(*value++);
1674                 }
1675         }
1676         entry->e_hash = cpu_to_le32(hash);
1677 }
1678
1679 #undef NAME_HASH_SHIFT
1680 #undef VALUE_HASH_SHIFT
1681
1682 #define BLOCK_HASH_SHIFT 16
1683
1684 /*
1685  * ext4_xattr_rehash()
1686  *
1687  * Re-compute the extended attribute hash value after an entry has changed.
1688  */
1689 static void ext4_xattr_rehash(struct ext4_xattr_header *header,
1690                               struct ext4_xattr_entry *entry)
1691 {
1692         struct ext4_xattr_entry *here;
1693         __u32 hash = 0;
1694
1695         ext4_xattr_hash_entry(header, entry);
1696         here = ENTRY(header+1);
1697         while (!IS_LAST_ENTRY(here)) {
1698                 if (!here->e_hash) {
1699                         /* Block is not shared if an entry's hash value == 0 */
1700                         hash = 0;
1701                         break;
1702                 }
1703                 hash = (hash << BLOCK_HASH_SHIFT) ^
1704                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1705                        le32_to_cpu(here->e_hash);
1706                 here = EXT4_XATTR_NEXT(here);
1707         }
1708         header->h_hash = cpu_to_le32(hash);
1709 }
1710
1711 #undef BLOCK_HASH_SHIFT
1712
1713 #define HASH_BUCKET_BITS        10
1714
1715 struct mb_cache *
1716 ext4_xattr_create_cache(char *name)
1717 {
1718         return mb_cache_create(name, HASH_BUCKET_BITS);
1719 }
1720
1721 void ext4_xattr_destroy_cache(struct mb_cache *cache)
1722 {
1723         if (cache)
1724                 mb_cache_destroy(cache);
1725 }
1726