fs/ext4/xattr.c

   1 /*
   2  * linux/fs/ext4/xattr.c
   3  *
   4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <[email protected]>
   5  *
   6  * Fix by Harrison Xing <[email protected]>.
   7  * Ext4 code with a lot of help from Eric Jarman <[email protected]>.
   8  * Extended attributes for symlinks and special files added per
   9  *  suggestion of Luka Renko <[email protected]>.
  10  * xattr consolidation Copyright (c) 2004 James Morris <[email protected]>,
  11  *  Red Hat Inc.
  12  * ea-in-inode support by Alex Tomas <[email protected]> aka bzzz
  13  *  and Andreas Gruenbacher <[email protected]>.
  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 <linux/rwsem.h>
  59 #include "ext4_jbd2.h"
  60 #include "ext4.h"
  61 #include "xattr.h"
  62 #include "acl.h"
  63
  64 #ifdef EXT4_XATTR_DEBUG
  65 # define ea_idebug(inode, f...) do { \
  66                 printk(KERN_DEBUG "inode %s:%lu: ", \
  67                         inode->i_sb->s_id, inode->i_ino); \
  68                 printk(f); \
  69                 printk("\n"); \
  70         } while (0)
  71 # define ea_bdebug(bh, f...) do { \
  72                 char b[BDEVNAME_SIZE]; \
  73                 printk(KERN_DEBUG "block %s:%lu: ", \
  74                         bdevname(bh->b_bdev, b), \
  75                         (unsigned long) bh->b_blocknr); \
  76                 printk(f); \
  77                 printk("\n"); \
  78         } while (0)
  79 #else
  80 # define ea_idebug(inode, fmt, ...)     no_printk(fmt, ##__VA_ARGS__)
  81 # define ea_bdebug(bh, fmt, ...)        no_printk(fmt, ##__VA_ARGS__)
  82 #endif
  83
  84 static void ext4_xattr_cache_insert(struct mb_cache *, struct buffer_head *);
  85 static struct buffer_head *ext4_xattr_cache_find(struct inode *,
  86                                                  struct ext4_xattr_header *,
  87                                                  struct mb_cache_entry **);
  88 static void ext4_xattr_rehash(struct ext4_xattr_header *,
  89                               struct ext4_xattr_entry *);
  90 static int ext4_xattr_list(struct dentry *dentry, char *buffer,
  91                            size_t buffer_size);
  92
  93 static const struct xattr_handler *ext4_xattr_handler_map[] = {
  94         [EXT4_XATTR_INDEX_USER]              = &ext4_xattr_user_handler,
  95 #ifdef CONFIG_EXT4_FS_POSIX_ACL
  96         [EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &posix_acl_access_xattr_handler,
  97         [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
  98 #endif
  99         [EXT4_XATTR_INDEX_TRUSTED]           = &ext4_xattr_trusted_handler,
 100 #ifdef CONFIG_EXT4_FS_SECURITY
 101         [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
 102 #endif
 103 };
 104
 105 const struct xattr_handler *ext4_xattr_handlers[] = {
 106         &ext4_xattr_user_handler,
 107         &ext4_xattr_trusted_handler,
 108 #ifdef CONFIG_EXT4_FS_POSIX_ACL
 109         &posix_acl_access_xattr_handler,
 110         &posix_acl_default_xattr_handler,
 111 #endif
 112 #ifdef CONFIG_EXT4_FS_SECURITY
 113         &ext4_xattr_security_handler,
 114 #endif
 115         NULL
 116 };
 117
 118 #define EXT4_GET_MB_CACHE(inode)        (((struct ext4_sb_info *) \
 119                                 inode->i_sb->s_fs_info)->s_mb_cache)
 120
 121 static __le32 ext4_xattr_block_csum(struct inode *inode,
 122                                     sector_t block_nr,
 123                                     struct ext4_xattr_header *hdr)
 124 {
 125         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 126         __u32 csum;
 127         __le32 save_csum;
 128         __le64 dsk_block_nr = cpu_to_le64(block_nr);
 129
 130         save_csum = hdr->h_checksum;
 131         hdr->h_checksum = 0;
 132         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&dsk_block_nr,
 133                            sizeof(dsk_block_nr));
 134         csum = ext4_chksum(sbi, csum, (__u8 *)hdr,
 135                            EXT4_BLOCK_SIZE(inode->i_sb));
 136
 137         hdr->h_checksum = save_csum;
 138         return cpu_to_le32(csum);
 139 }
 140
 141 static int ext4_xattr_block_csum_verify(struct inode *inode,
 142                                         sector_t block_nr,
 143                                         struct ext4_xattr_header *hdr)
 144 {
 145         if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
 146                 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) &&
 147             (hdr->h_checksum != ext4_xattr_block_csum(inode, block_nr, hdr)))
 148                 return 0;
 149         return 1;
 150 }
 151
 152 static void ext4_xattr_block_csum_set(struct inode *inode,
 153                                       sector_t block_nr,
 154                                       struct ext4_xattr_header *hdr)
 155 {
 156         if (!EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
 157                 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
 158                 return;
 159
 160         hdr->h_checksum = ext4_xattr_block_csum(inode, block_nr, hdr);
 161 }
 162
 163 static inline int ext4_handle_dirty_xattr_block(handle_t *handle,
 164                                                 struct inode *inode,
 165                                                 struct buffer_head *bh)
 166 {
 167         ext4_xattr_block_csum_set(inode, bh->b_blocknr, BHDR(bh));
 168         return ext4_handle_dirty_metadata(handle, inode, bh);
 169 }
 170
 171 static inline const struct xattr_handler *
 172 ext4_xattr_handler(int name_index)
 173 {
 174         const struct xattr_handler *handler = NULL;
 175
 176         if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
 177                 handler = ext4_xattr_handler_map[name_index];
 178         return handler;
 179 }
 180
 181 /*
 182  * Inode operation listxattr()
 183  *
 184  * dentry->d_inode->i_mutex: don't care
 185  */
 186 ssize_t
 187 ext4_listxattr(struct dentry *dentry, char *buffer, size_t size)
 188 {
 189         return ext4_xattr_list(dentry, buffer, size);
 190 }
 191
 192 static int
 193 ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end)
 194 {
 195         while (!IS_LAST_ENTRY(entry)) {
 196                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(entry);
 197                 if ((void *)next >= end)
 198                         return -EIO;
 199                 entry = next;
 200         }
 201         return 0;
 202 }
 203
 204 static inline int
 205 ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh)
 206 {
 207         int error;
 208
 209         if (buffer_verified(bh))
 210                 return 0;
 211
 212         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
 213             BHDR(bh)->h_blocks != cpu_to_le32(1))
 214                 return -EIO;
 215         if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh)))
 216                 return -EIO;
 217         error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
 218         if (!error)
 219                 set_buffer_verified(bh);
 220         return error;
 221 }
 222
 223 static inline int
 224 ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size)
 225 {
 226         size_t value_size = le32_to_cpu(entry->e_value_size);
 227
 228         if (entry->e_value_block != 0 || value_size > size ||
 229             le16_to_cpu(entry->e_value_offs) + value_size > size)
 230                 return -EIO;
 231         return 0;
 232 }
 233
 234 static int
 235 ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
 236                       const char *name, size_t size, int sorted)
 237 {
 238         struct ext4_xattr_entry *entry;
 239         size_t name_len;
 240         int cmp = 1;
 241
 242         if (name == NULL)
 243                 return -EINVAL;
 244         name_len = strlen(name);
 245         entry = *pentry;
 246         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 247                 cmp = name_index - entry->e_name_index;
 248                 if (!cmp)
 249                         cmp = name_len - entry->e_name_len;
 250                 if (!cmp)
 251                         cmp = memcmp(name, entry->e_name, name_len);
 252                 if (cmp <= 0 && (sorted || cmp == 0))
 253                         break;
 254         }
 255         *pentry = entry;
 256         if (!cmp && ext4_xattr_check_entry(entry, size))
 257                         return -EIO;
 258         return cmp ? -ENODATA : 0;
 259 }
 260
 261 static int
 262 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
 263                      void *buffer, size_t buffer_size)
 264 {
 265         struct buffer_head *bh = NULL;
 266         struct ext4_xattr_entry *entry;
 267         size_t size;
 268         int error;
 269         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 270
 271         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 272                   name_index, name, buffer, (long)buffer_size);
 273
 274         error = -ENODATA;
 275         if (!EXT4_I(inode)->i_file_acl)
 276                 goto cleanup;
 277         ea_idebug(inode, "reading block %llu",
 278                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 279         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 280         if (!bh)
 281                 goto cleanup;
 282         ea_bdebug(bh, "b_count=%d, refcount=%d",
 283                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 284         if (ext4_xattr_check_block(inode, bh)) {
 285 bad_block:
 286                 EXT4_ERROR_INODE(inode, "bad block %llu",
 287                                  EXT4_I(inode)->i_file_acl);
 288                 error = -EIO;
 289                 goto cleanup;
 290         }
 291         ext4_xattr_cache_insert(ext4_mb_cache, bh);
 292         entry = BFIRST(bh);
 293         error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
 294         if (error == -EIO)
 295                 goto bad_block;
 296         if (error)
 297                 goto cleanup;
 298         size = le32_to_cpu(entry->e_value_size);
 299         if (buffer) {
 300                 error = -ERANGE;
 301                 if (size > buffer_size)
 302                         goto cleanup;
 303                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
 304                        size);
 305         }
 306         error = size;
 307
 308 cleanup:
 309         brelse(bh);
 310         return error;
 311 }
 312
 313 int
 314 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 315                      void *buffer, size_t buffer_size)
 316 {
 317         struct ext4_xattr_ibody_header *header;
 318         struct ext4_xattr_entry *entry;
 319         struct ext4_inode *raw_inode;
 320         struct ext4_iloc iloc;
 321         size_t size;
 322         void *end;
 323         int error;
 324
 325         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 326                 return -ENODATA;
 327         error = ext4_get_inode_loc(inode, &iloc);
 328         if (error)
 329                 return error;
 330         raw_inode = ext4_raw_inode(&iloc);
 331         header = IHDR(inode, raw_inode);
 332         entry = IFIRST(header);
 333         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 334         error = ext4_xattr_check_names(entry, end);
 335         if (error)
 336                 goto cleanup;
 337         error = ext4_xattr_find_entry(&entry, name_index, name,
 338                                       end - (void *)entry, 0);
 339         if (error)
 340                 goto cleanup;
 341         size = le32_to_cpu(entry->e_value_size);
 342         if (buffer) {
 343                 error = -ERANGE;
 344                 if (size > buffer_size)
 345                         goto cleanup;
 346                 memcpy(buffer, (void *)IFIRST(header) +
 347                        le16_to_cpu(entry->e_value_offs), size);
 348         }
 349         error = size;
 350
 351 cleanup:
 352         brelse(iloc.bh);
 353         return error;
 354 }
 355
 356 /*
 357  * ext4_xattr_get()
 358  *
 359  * Copy an extended attribute into the buffer
 360  * provided, or compute the buffer size required.
 361  * Buffer is NULL to compute the size of the buffer required.
 362  *
 363  * Returns a negative error number on failure, or the number of bytes
 364  * used / required on success.
 365  */
 366 int
 367 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
 368                void *buffer, size_t buffer_size)
 369 {
 370         int error;
 371
 372         if (strlen(name) > 255)
 373                 return -ERANGE;
 374
 375         down_read(&EXT4_I(inode)->xattr_sem);
 376         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
 377                                      buffer_size);
 378         if (error == -ENODATA)
 379                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
 380                                              buffer_size);
 381         up_read(&EXT4_I(inode)->xattr_sem);
 382         return error;
 383 }
 384
 385 static int
 386 ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,
 387                         char *buffer, size_t buffer_size)
 388 {
 389         size_t rest = buffer_size;
 390
 391         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 392                 const struct xattr_handler *handler =
 393                         ext4_xattr_handler(entry->e_name_index);
 394
 395                 if (handler) {
 396                         size_t size = handler->list(dentry, buffer, rest,
 397                                                     entry->e_name,
 398                                                     entry->e_name_len,
 399                                                     handler->flags);
 400                         if (buffer) {
 401                                 if (size > rest)
 402                                         return -ERANGE;
 403                                 buffer += size;
 404                         }
 405                         rest -= size;
 406                 }
 407         }
 408         return buffer_size - rest;
 409 }
 410
 411 static int
 412 ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 413 {
 414         struct inode *inode = dentry->d_inode;
 415         struct buffer_head *bh = NULL;
 416         int error;
 417         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 418
 419         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 420                   buffer, (long)buffer_size);
 421
 422         error = 0;
 423         if (!EXT4_I(inode)->i_file_acl)
 424                 goto cleanup;
 425         ea_idebug(inode, "reading block %llu",
 426                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 427         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 428         error = -EIO;
 429         if (!bh)
 430                 goto cleanup;
 431         ea_bdebug(bh, "b_count=%d, refcount=%d",
 432                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 433         if (ext4_xattr_check_block(inode, bh)) {
 434                 EXT4_ERROR_INODE(inode, "bad block %llu",
 435                                  EXT4_I(inode)->i_file_acl);
 436                 error = -EIO;
 437                 goto cleanup;
 438         }
 439         ext4_xattr_cache_insert(ext4_mb_cache, bh);
 440         error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
 441
 442 cleanup:
 443         brelse(bh);
 444
 445         return error;
 446 }
 447
 448 static int
 449 ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 450 {
 451         struct inode *inode = dentry->d_inode;
 452         struct ext4_xattr_ibody_header *header;
 453         struct ext4_inode *raw_inode;
 454         struct ext4_iloc iloc;
 455         void *end;
 456         int error;
 457
 458         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 459                 return 0;
 460         error = ext4_get_inode_loc(inode, &iloc);
 461         if (error)
 462                 return error;
 463         raw_inode = ext4_raw_inode(&iloc);
 464         header = IHDR(inode, raw_inode);
 465         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 466         error = ext4_xattr_check_names(IFIRST(header), end);
 467         if (error)
 468                 goto cleanup;
 469         error = ext4_xattr_list_entries(dentry, IFIRST(header),
 470                                         buffer, buffer_size);
 471
 472 cleanup:
 473         brelse(iloc.bh);
 474         return error;
 475 }
 476
 477 /*
 478  * ext4_xattr_list()
 479  *
 480  * Copy a list of attribute names into the buffer
 481  * provided, or compute the buffer size required.
 482  * Buffer is NULL to compute the size of the buffer required.
 483  *
 484  * Returns a negative error number on failure, or the number of bytes
 485  * used / required on success.
 486  */
 487 static int
 488 ext4_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 489 {
 490         int ret, ret2;
 491
 492         down_read(&EXT4_I(dentry->d_inode)->xattr_sem);
 493         ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size);
 494         if (ret < 0)
 495                 goto errout;
 496         if (buffer) {
 497                 buffer += ret;
 498                 buffer_size -= ret;
 499         }
 500         ret = ext4_xattr_block_list(dentry, buffer, buffer_size);
 501         if (ret < 0)
 502                 goto errout;
 503         ret += ret2;
 504 errout:
 505         up_read(&EXT4_I(dentry->d_inode)->xattr_sem);
 506         return ret;
 507 }
 508
 509 /*
 510  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 511  * not set, set it.
 512  */
 513 static void ext4_xattr_update_super_block(handle_t *handle,
 514                                           struct super_block *sb)
 515 {
 516         if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR))
 517                 return;
 518
 519         BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
 520         if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
 521                 EXT4_SET_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR);
 522                 ext4_handle_dirty_super(handle, sb);
 523         }
 524 }
 525
 526 /*
 527  * Release the xattr block BH: If the reference count is > 1, decrement it;
 528  * otherwise free the block.
 529  */
 530 static void
 531 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
 532                          struct buffer_head *bh)
 533 {
 534         struct mb_cache_entry *ce = NULL;
 535         int error = 0;
 536         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 537
 538         ce = mb_cache_entry_get(ext4_mb_cache, bh->b_bdev, bh->b_blocknr);
 539         BUFFER_TRACE(bh, "get_write_access");
 540         error = ext4_journal_get_write_access(handle, bh);
 541         if (error)
 542                 goto out;
 543
 544         lock_buffer(bh);
 545         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
 546                 ea_bdebug(bh, "refcount now=0; freeing");
 547                 if (ce)
 548                         mb_cache_entry_free(ce);
 549                 get_bh(bh);
 550                 unlock_buffer(bh);
 551                 ext4_free_blocks(handle, inode, bh, 0, 1,
 552                                  EXT4_FREE_BLOCKS_METADATA |
 553                                  EXT4_FREE_BLOCKS_FORGET);
 554         } else {
 555                 le32_add_cpu(&BHDR(bh)->h_refcount, -1);
 556                 if (ce)
 557                         mb_cache_entry_release(ce);
 558                 /*
 559                  * Beware of this ugliness: Releasing of xattr block references
 560                  * from different inodes can race and so we have to protect
 561                  * from a race where someone else frees the block (and releases
 562                  * its journal_head) before we are done dirtying the buffer. In
 563                  * nojournal mode this race is harmless and we actually cannot
 564                  * call ext4_handle_dirty_xattr_block() with locked buffer as
 565                  * that function can call sync_dirty_buffer() so for that case
 566                  * we handle the dirtying after unlocking the buffer.
 567                  */
 568                 if (ext4_handle_valid(handle))
 569                         error = ext4_handle_dirty_xattr_block(handle, inode,
 570                                                               bh);
 571                 unlock_buffer(bh);
 572                 if (!ext4_handle_valid(handle))
 573                         error = ext4_handle_dirty_xattr_block(handle, inode,
 574                                                               bh);
 575                 if (IS_SYNC(inode))
 576                         ext4_handle_sync(handle);
 577                 dquot_free_block(inode, EXT4_C2B(EXT4_SB(inode->i_sb), 1));
 578                 ea_bdebug(bh, "refcount now=%d; releasing",
 579                           le32_to_cpu(BHDR(bh)->h_refcount));
 580         }
 581 out:
 582         ext4_std_error(inode->i_sb, error);
 583         return;
 584 }
 585
 586 /*
 587  * Find the available free space for EAs. This also returns the total number of
 588  * bytes used by EA entries.
 589  */
 590 static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
 591                                     size_t *min_offs, void *base, int *total)
 592 {
 593         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 594                 if (!last->e_value_block && last->e_value_size) {
 595                         size_t offs = le16_to_cpu(last->e_value_offs);
 596                         if (offs < *min_offs)
 597                                 *min_offs = offs;
 598                 }
 599                 if (total)
 600                         *total += EXT4_XATTR_LEN(last->e_name_len);
 601         }
 602         return (*min_offs - ((void *)last - base) - sizeof(__u32));
 603 }
 604
 605 static int
 606 ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
 607 {
 608         struct ext4_xattr_entry *last;
 609         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
 610
 611         /* Compute min_offs and last. */
 612         last = s->first;
 613         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 614                 if (!last->e_value_block && last->e_value_size) {
 615                         size_t offs = le16_to_cpu(last->e_value_offs);
 616                         if (offs < min_offs)
 617                                 min_offs = offs;
 618                 }
 619         }
 620         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
 621         if (!s->not_found) {
 622                 if (!s->here->e_value_block && s->here->e_value_size) {
 623                         size_t size = le32_to_cpu(s->here->e_value_size);
 624                         free += EXT4_XATTR_SIZE(size);
 625                 }
 626                 free += EXT4_XATTR_LEN(name_len);
 627         }
 628         if (i->value) {
 629                 if (free < EXT4_XATTR_SIZE(i->value_len) ||
 630                     free < EXT4_XATTR_LEN(name_len) +
 631                            EXT4_XATTR_SIZE(i->value_len))
 632                         return -ENOSPC;
 633         }
 634
 635         if (i->value && s->not_found) {
 636                 /* Insert the new name. */
 637                 size_t size = EXT4_XATTR_LEN(name_len);
 638                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
 639                 memmove((void *)s->here + size, s->here, rest);
 640                 memset(s->here, 0, size);
 641                 s->here->e_name_index = i->name_index;
 642                 s->here->e_name_len = name_len;
 643                 memcpy(s->here->e_name, i->name, name_len);
 644         } else {
 645                 if (!s->here->e_value_block && s->here->e_value_size) {
 646                         void *first_val = s->base + min_offs;
 647                         size_t offs = le16_to_cpu(s->here->e_value_offs);
 648                         void *val = s->base + offs;
 649                         size_t size = EXT4_XATTR_SIZE(
 650                                 le32_to_cpu(s->here->e_value_size));
 651
 652                         if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
 653                                 /* The old and the new value have the same
 654                                    size. Just replace. */
 655                                 s->here->e_value_size =
 656                                         cpu_to_le32(i->value_len);
 657                                 if (i->value == EXT4_ZERO_XATTR_VALUE) {
 658                                         memset(val, 0, size);
 659                                 } else {
 660                                         /* Clear pad bytes first. */
 661                                         memset(val + size - EXT4_XATTR_PAD, 0,
 662                                                EXT4_XATTR_PAD);
 663                                         memcpy(val, i->value, i->value_len);
 664                                 }
 665                                 return 0;
 666                         }
 667
 668                         /* Remove the old value. */
 669                         memmove(first_val + size, first_val, val - first_val);
 670                         memset(first_val, 0, size);
 671                         s->here->e_value_size = 0;
 672                         s->here->e_value_offs = 0;
 673                         min_offs += size;
 674
 675                         /* Adjust all value offsets. */
 676                         last = s->first;
 677                         while (!IS_LAST_ENTRY(last)) {
 678                                 size_t o = le16_to_cpu(last->e_value_offs);
 679                                 if (!last->e_value_block &&
 680                                     last->e_value_size && o < offs)
 681                                         last->e_value_offs =
 682                                                 cpu_to_le16(o + size);
 683                                 last = EXT4_XATTR_NEXT(last);
 684                         }
 685                 }
 686                 if (!i->value) {
 687                         /* Remove the old name. */
 688                         size_t size = EXT4_XATTR_LEN(name_len);
 689                         last = ENTRY((void *)last - size);
 690                         memmove(s->here, (void *)s->here + size,
 691                                 (void *)last - (void *)s->here + sizeof(__u32));
 692                         memset(last, 0, size);
 693                 }
 694         }
 695
 696         if (i->value) {
 697                 /* Insert the new value. */
 698                 s->here->e_value_size = cpu_to_le32(i->value_len);
 699                 if (i->value_len) {
 700                         size_t size = EXT4_XATTR_SIZE(i->value_len);
 701                         void *val = s->base + min_offs - size;
 702                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
 703                         if (i->value == EXT4_ZERO_XATTR_VALUE) {
 704                                 memset(val, 0, size);
 705                         } else {
 706                                 /* Clear the pad bytes first. */
 707                                 memset(val + size - EXT4_XATTR_PAD, 0,
 708                                        EXT4_XATTR_PAD);
 709                                 memcpy(val, i->value, i->value_len);
 710                         }
 711                 }
 712         }
 713         return 0;
 714 }
 715
 716 struct ext4_xattr_block_find {
 717         struct ext4_xattr_search s;
 718         struct buffer_head *bh;
 719 };
 720
 721 static int
 722 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
 723                       struct ext4_xattr_block_find *bs)
 724 {
 725         struct super_block *sb = inode->i_sb;
 726         int error;
 727
 728         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
 729                   i->name_index, i->name, i->value, (long)i->value_len);
 730
 731         if (EXT4_I(inode)->i_file_acl) {
 732                 /* The inode already has an extended attribute block. */
 733                 bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);
 734                 error = -EIO;
 735                 if (!bs->bh)
 736                         goto cleanup;
 737                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
 738                         atomic_read(&(bs->bh->b_count)),
 739                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
 740                 if (ext4_xattr_check_block(inode, bs->bh)) {
 741                         EXT4_ERROR_INODE(inode, "bad block %llu",
 742                                          EXT4_I(inode)->i_file_acl);
 743                         error = -EIO;
 744                         goto cleanup;
 745                 }
 746                 /* Find the named attribute. */
 747                 bs->s.base = BHDR(bs->bh);
 748                 bs->s.first = BFIRST(bs->bh);
 749                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
 750                 bs->s.here = bs->s.first;
 751                 error = ext4_xattr_find_entry(&bs->s.here, i->name_index,
 752                                               i->name, bs->bh->b_size, 1);
 753                 if (error && error != -ENODATA)
 754                         goto cleanup;
 755                 bs->s.not_found = error;
 756         }
 757         error = 0;
 758
 759 cleanup:
 760         return error;
 761 }
 762
 763 static int
 764 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
 765                      struct ext4_xattr_info *i,
 766                      struct ext4_xattr_block_find *bs)
 767 {
 768         struct super_block *sb = inode->i_sb;
 769         struct buffer_head *new_bh = NULL;
 770         struct ext4_xattr_search *s = &bs->s;
 771         struct mb_cache_entry *ce = NULL;
 772         int error = 0;
 773         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 774
 775 #define header(x) ((struct ext4_xattr_header *)(x))
 776
 777         if (i->value && i->value_len > sb->s_blocksize)
 778                 return -ENOSPC;
 779         if (s->base) {
 780                 ce = mb_cache_entry_get(ext4_mb_cache, bs->bh->b_bdev,
 781                                         bs->bh->b_blocknr);
 782                 BUFFER_TRACE(bs->bh, "get_write_access");
 783                 error = ext4_journal_get_write_access(handle, bs->bh);
 784                 if (error)
 785                         goto cleanup;
 786                 lock_buffer(bs->bh);
 787
 788                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 789                         if (ce) {
 790                                 mb_cache_entry_free(ce);
 791                                 ce = NULL;
 792                         }
 793                         ea_bdebug(bs->bh, "modifying in-place");
 794                         error = ext4_xattr_set_entry(i, s);
 795                         if (!error) {
 796                                 if (!IS_LAST_ENTRY(s->first))
 797                                         ext4_xattr_rehash(header(s->base),
 798                                                           s->here);
 799                                 ext4_xattr_cache_insert(ext4_mb_cache,
 800                                         bs->bh);
 801                         }
 802                         unlock_buffer(bs->bh);
 803                         if (error == -EIO)
 804                                 goto bad_block;
 805                         if (!error)
 806                                 error = ext4_handle_dirty_xattr_block(handle,
 807                                                                       inode,
 808                                                                       bs->bh);
 809                         if (error)
 810                                 goto cleanup;
 811                         goto inserted;
 812                 } else {
 813                         int offset = (char *)s->here - bs->bh->b_data;
 814
 815                         unlock_buffer(bs->bh);
 816                         if (ce) {
 817                                 mb_cache_entry_release(ce);
 818                                 ce = NULL;
 819                         }
 820                         ea_bdebug(bs->bh, "cloning");
 821                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
 822                         error = -ENOMEM;
 823                         if (s->base == NULL)
 824                                 goto cleanup;
 825                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 826                         s->first = ENTRY(header(s->base)+1);
 827                         header(s->base)->h_refcount = cpu_to_le32(1);
 828                         s->here = ENTRY(s->base + offset);
 829                         s->end = s->base + bs->bh->b_size;
 830                 }
 831         } else {
 832                 /* Allocate a buffer where we construct the new block. */
 833                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
 834                 /* assert(header == s->base) */
 835                 error = -ENOMEM;
 836                 if (s->base == NULL)
 837                         goto cleanup;
 838                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
 839                 header(s->base)->h_blocks = cpu_to_le32(1);
 840                 header(s->base)->h_refcount = cpu_to_le32(1);
 841                 s->first = ENTRY(header(s->base)+1);
 842                 s->here = ENTRY(header(s->base)+1);
 843                 s->end = s->base + sb->s_blocksize;
 844         }
 845
 846         error = ext4_xattr_set_entry(i, s);
 847         if (error == -EIO)
 848                 goto bad_block;
 849         if (error)
 850                 goto cleanup;
 851         if (!IS_LAST_ENTRY(s->first))
 852                 ext4_xattr_rehash(header(s->base), s->here);
 853
 854 inserted:
 855         if (!IS_LAST_ENTRY(s->first)) {
 856                 new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);
 857                 if (new_bh) {
 858                         /* We found an identical block in the cache. */
 859                         if (new_bh == bs->bh)
 860                                 ea_bdebug(new_bh, "keeping");
 861                         else {
 862                                 /* The old block is released after updating
 863                                    the inode. */
 864                                 error = dquot_alloc_block(inode,
 865                                                 EXT4_C2B(EXT4_SB(sb), 1));
 866                                 if (error)
 867                                         goto cleanup;
 868                                 BUFFER_TRACE(new_bh, "get_write_access");
 869                                 error = ext4_journal_get_write_access(handle,
 870                                                                       new_bh);
 871                                 if (error)
 872                                         goto cleanup_dquot;
 873                                 lock_buffer(new_bh);
 874                                 le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
 875                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
 876                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 877                                 unlock_buffer(new_bh);
 878                                 error = ext4_handle_dirty_xattr_block(handle,
 879                                                                       inode,
 880                                                                       new_bh);
 881                                 if (error)
 882                                         goto cleanup_dquot;
 883                         }
 884                         mb_cache_entry_release(ce);
 885                         ce = NULL;
 886                 } else if (bs->bh && s->base == bs->bh->b_data) {
 887                         /* We were modifying this block in-place. */
 888                         ea_bdebug(bs->bh, "keeping this block");
 889                         new_bh = bs->bh;
 890                         get_bh(new_bh);
 891                 } else {
 892                         /* We need to allocate a new block */
 893                         ext4_fsblk_t goal, block;
 894
 895                         goal = ext4_group_first_block_no(sb,
 896                                                 EXT4_I(inode)->i_block_group);
 897
 898                         /* non-extent files can't have physical blocks past 2^32 */
 899                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 900                                 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
 901
 902                         /*
 903                          * take i_data_sem because we will test
 904                          * i_delalloc_reserved_flag in ext4_mb_new_blocks
 905                          */
 906                         down_read(&EXT4_I(inode)->i_data_sem);
 907                         block = ext4_new_meta_blocks(handle, inode, goal, 0,
 908                                                      NULL, &error);
 909                         up_read((&EXT4_I(inode)->i_data_sem));
 910                         if (error)
 911                                 goto cleanup;
 912
 913                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 914                                 BUG_ON(block > EXT4_MAX_BLOCK_FILE_PHYS);
 915
 916                         ea_idebug(inode, "creating block %llu",
 917                                   (unsigned long long)block);
 918
 919                         new_bh = sb_getblk(sb, block);
 920                         if (unlikely(!new_bh)) {
 921                                 error = -ENOMEM;
 922 getblk_failed:
 923                                 ext4_free_blocks(handle, inode, NULL, block, 1,
 924                                                  EXT4_FREE_BLOCKS_METADATA);
 925                                 goto cleanup;
 926                         }
 927                         lock_buffer(new_bh);
 928                         error = ext4_journal_get_create_access(handle, new_bh);
 929                         if (error) {
 930                                 unlock_buffer(new_bh);
 931                                 error = -EIO;
 932                                 goto getblk_failed;
 933                         }
 934                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
 935                         set_buffer_uptodate(new_bh);
 936                         unlock_buffer(new_bh);
 937                         ext4_xattr_cache_insert(ext4_mb_cache, new_bh);
 938                         error = ext4_handle_dirty_xattr_block(handle,
 939                                                               inode, new_bh);
 940                         if (error)
 941                                 goto cleanup;
 942                 }
 943         }
 944
 945         /* Update the inode. */
 946         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
 947
 948         /* Drop the previous xattr block. */
 949         if (bs->bh && bs->bh != new_bh)
 950                 ext4_xattr_release_block(handle, inode, bs->bh);
 951         error = 0;
 952
 953 cleanup:
 954         if (ce)
 955                 mb_cache_entry_release(ce);
 956         brelse(new_bh);
 957         if (!(bs->bh && s->base == bs->bh->b_data))
 958                 kfree(s->base);
 959
 960         return error;
 961
 962 cleanup_dquot:
 963         dquot_free_block(inode, EXT4_C2B(EXT4_SB(sb), 1));
 964         goto cleanup;
 965
 966 bad_block:
 967         EXT4_ERROR_INODE(inode, "bad block %llu",
 968                          EXT4_I(inode)->i_file_acl);
 969         goto cleanup;
 970
 971 #undef header
 972 }
 973
 974 int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
 975                           struct ext4_xattr_ibody_find *is)
 976 {
 977         struct ext4_xattr_ibody_header *header;
 978         struct ext4_inode *raw_inode;
 979         int error;
 980
 981         if (EXT4_I(inode)->i_extra_isize == 0)
 982                 return 0;
 983         raw_inode = ext4_raw_inode(&is->iloc);
 984         header = IHDR(inode, raw_inode);
 985         is->s.base = is->s.first = IFIRST(header);
 986         is->s.here = is->s.first;
 987         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 988         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
 989                 error = ext4_xattr_check_names(IFIRST(header), is->s.end);
 990                 if (error)
 991                         return error;
 992                 /* Find the named attribute. */
 993                 error = ext4_xattr_find_entry(&is->s.here, i->name_index,
 994                                               i->name, is->s.end -
 995                                               (void *)is->s.base, 0);
 996                 if (error && error != -ENODATA)
 997                         return error;
 998                 is->s.not_found = error;
 999         }
1000         return 0;
1001 }
1002
1003 int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode,
1004                                 struct ext4_xattr_info *i,
1005                                 struct ext4_xattr_ibody_find *is)
1006 {
1007         struct ext4_xattr_ibody_header *header;
1008         struct ext4_xattr_search *s = &is->s;
1009         int error;
1010
1011         if (EXT4_I(inode)->i_extra_isize == 0)
1012                 return -ENOSPC;
1013         error = ext4_xattr_set_entry(i, s);
1014         if (error) {
1015                 if (error == -ENOSPC &&
1016                     ext4_has_inline_data(inode)) {
1017                         error = ext4_try_to_evict_inline_data(handle, inode,
1018                                         EXT4_XATTR_LEN(strlen(i->name) +
1019                                         EXT4_XATTR_SIZE(i->value_len)));
1020                         if (error)
1021                                 return error;
1022                         error = ext4_xattr_ibody_find(inode, i, is);
1023                         if (error)
1024                                 return error;
1025                         error = ext4_xattr_set_entry(i, s);
1026                 }
1027                 if (error)
1028                         return error;
1029         }
1030         header = IHDR(inode, ext4_raw_inode(&is->iloc));
1031         if (!IS_LAST_ENTRY(s->first)) {
1032                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1033                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
1034         } else {
1035                 header->h_magic = cpu_to_le32(0);
1036                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
1037         }
1038         return 0;
1039 }
1040
1041 static int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
1042                                 struct ext4_xattr_info *i,
1043                                 struct ext4_xattr_ibody_find *is)
1044 {
1045         struct ext4_xattr_ibody_header *header;
1046         struct ext4_xattr_search *s = &is->s;
1047         int error;
1048
1049         if (EXT4_I(inode)->i_extra_isize == 0)
1050                 return -ENOSPC;
1051         error = ext4_xattr_set_entry(i, s);
1052         if (error)
1053                 return error;
1054         header = IHDR(inode, ext4_raw_inode(&is->iloc));
1055         if (!IS_LAST_ENTRY(s->first)) {
1056                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1057                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
1058         } else {
1059                 header->h_magic = cpu_to_le32(0);
1060                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
1061         }
1062         return 0;
1063 }
1064
1065 /*
1066  * ext4_xattr_set_handle()
1067  *
1068  * Create, replace or remove an extended attribute for this inode.  Value
1069  * is NULL to remove an existing extended attribute, and non-NULL to
1070  * either replace an existing extended attribute, or create a new extended
1071  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
1072  * specify that an extended attribute must exist and must not exist
1073  * previous to the call, respectively.
1074  *
1075  * Returns 0, or a negative error number on failure.
1076  */
1077 int
1078 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
1079                       const char *name, const void *value, size_t value_len,
1080                       int flags)
1081 {
1082         struct ext4_xattr_info i = {
1083                 .name_index = name_index,
1084                 .name = name,
1085                 .value = value,
1086                 .value_len = value_len,
1087
1088         };
1089         struct ext4_xattr_ibody_find is = {
1090                 .s = { .not_found = -ENODATA, },
1091         };
1092         struct ext4_xattr_block_find bs = {
1093                 .s = { .not_found = -ENODATA, },
1094         };
1095         unsigned long no_expand;
1096         int error;
1097
1098         if (!name)
1099                 return -EINVAL;
1100         if (strlen(name) > 255)
1101                 return -ERANGE;
1102         down_write(&EXT4_I(inode)->xattr_sem);
1103         no_expand = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
1104         ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
1105
1106         error = ext4_reserve_inode_write(handle, inode, &is.iloc);
1107         if (error)
1108                 goto cleanup;
1109
1110         if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) {
1111                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
1112                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
1113                 ext4_clear_inode_state(inode, EXT4_STATE_NEW);
1114         }
1115
1116         error = ext4_xattr_ibody_find(inode, &i, &is);
1117         if (error)
1118                 goto cleanup;
1119         if (is.s.not_found)
1120                 error = ext4_xattr_block_find(inode, &i, &bs);
1121         if (error)
1122                 goto cleanup;
1123         if (is.s.not_found && bs.s.not_found) {
1124                 error = -ENODATA;
1125                 if (flags & XATTR_REPLACE)
1126                         goto cleanup;
1127                 error = 0;
1128                 if (!value)
1129                         goto cleanup;
1130         } else {
1131                 error = -EEXIST;
1132                 if (flags & XATTR_CREATE)
1133                         goto cleanup;
1134         }
1135         if (!value) {
1136                 if (!is.s.not_found)
1137                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1138                 else if (!bs.s.not_found)
1139                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1140         } else {
1141                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1142                 if (!error && !bs.s.not_found) {
1143                         i.value = NULL;
1144                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1145                 } else if (error == -ENOSPC) {
1146                         if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
1147                                 error = ext4_xattr_block_find(inode, &i, &bs);
1148                                 if (error)
1149                                         goto cleanup;
1150                         }
1151                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1152                         if (error)
1153                                 goto cleanup;
1154                         if (!is.s.not_found) {
1155                                 i.value = NULL;
1156                                 error = ext4_xattr_ibody_set(handle, inode, &i,
1157                                                              &is);
1158                         }
1159                 }
1160         }
1161         if (!error) {
1162                 ext4_xattr_update_super_block(handle, inode->i_sb);
1163                 inode->i_ctime = ext4_current_time(inode);
1164                 if (!value)
1165                         ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1166                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
1167                 /*
1168                  * The bh is consumed by ext4_mark_iloc_dirty, even with
1169                  * error != 0.
1170                  */
1171                 is.iloc.bh = NULL;
1172                 if (IS_SYNC(inode))
1173                         ext4_handle_sync(handle);
1174         }
1175
1176 cleanup:
1177         brelse(is.iloc.bh);
1178         brelse(bs.bh);
1179         if (no_expand == 0)
1180                 ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1181         up_write(&EXT4_I(inode)->xattr_sem);
1182         return error;
1183 }
1184
1185 /*
1186  * ext4_xattr_set()
1187  *
1188  * Like ext4_xattr_set_handle, but start from an inode. This extended
1189  * attribute modification is a filesystem transaction by itself.
1190  *
1191  * Returns 0, or a negative error number on failure.
1192  */
1193 int
1194 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
1195                const void *value, size_t value_len, int flags)
1196 {
1197         handle_t *handle;
1198         int error, retries = 0;
1199         int credits = ext4_jbd2_credits_xattr(inode);
1200
1201 retry:
1202         handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
1203         if (IS_ERR(handle)) {
1204                 error = PTR_ERR(handle);
1205         } else {
1206                 int error2;
1207
1208                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
1209                                               value, value_len, flags);
1210                 error2 = ext4_journal_stop(handle);
1211                 if (error == -ENOSPC &&
1212                     ext4_should_retry_alloc(inode->i_sb, &retries))
1213                         goto retry;
1214                 if (error == 0)
1215                         error = error2;
1216         }
1217
1218         return error;
1219 }
1220
1221 /*
1222  * Shift the EA entries in the inode to create space for the increased
1223  * i_extra_isize.
1224  */
1225 static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
1226                                      int value_offs_shift, void *to,
1227                                      void *from, size_t n, int blocksize)
1228 {
1229         struct ext4_xattr_entry *last = entry;
1230         int new_offs;
1231
1232         /* Adjust the value offsets of the entries */
1233         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1234                 if (!last->e_value_block && last->e_value_size) {
1235                         new_offs = le16_to_cpu(last->e_value_offs) +
1236                                                         value_offs_shift;
1237                         BUG_ON(new_offs + le32_to_cpu(last->e_value_size)
1238                                  > blocksize);
1239                         last->e_value_offs = cpu_to_le16(new_offs);
1240                 }
1241         }
1242         /* Shift the entries by n bytes */
1243         memmove(to, from, n);
1244 }
1245
1246 /*
1247  * Expand an inode by new_extra_isize bytes when EAs are present.
1248  * Returns 0 on success or negative error number on failure.
1249  */
1250 int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
1251                                struct ext4_inode *raw_inode, handle_t *handle)
1252 {
1253         struct ext4_xattr_ibody_header *header;
1254         struct ext4_xattr_entry *entry, *last, *first;
1255         struct buffer_head *bh = NULL;
1256         struct ext4_xattr_ibody_find *is = NULL;
1257         struct ext4_xattr_block_find *bs = NULL;
1258         char *buffer = NULL, *b_entry_name = NULL;
1259         size_t min_offs, free;
1260         int total_ino;
1261         void *base, *start, *end;
1262         int extra_isize = 0, error = 0, tried_min_extra_isize = 0;
1263         int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize);
1264
1265         down_write(&EXT4_I(inode)->xattr_sem);
1266 retry:
1267         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize) {
1268                 up_write(&EXT4_I(inode)->xattr_sem);
1269                 return 0;
1270         }
1271
1272         header = IHDR(inode, raw_inode);
1273         entry = IFIRST(header);
1274
1275         /*
1276          * Check if enough free space is available in the inode to shift the
1277          * entries ahead by new_extra_isize.
1278          */
1279
1280         base = start = entry;
1281         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
1282         min_offs = end - base;
1283         last = entry;
1284         total_ino = sizeof(struct ext4_xattr_ibody_header);
1285
1286         free = ext4_xattr_free_space(last, &min_offs, base, &total_ino);
1287         if (free >= new_extra_isize) {
1288                 entry = IFIRST(header);
1289                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize
1290                                 - new_extra_isize, (void *)raw_inode +
1291                                 EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
1292                                 (void *)header, total_ino,
1293                                 inode->i_sb->s_blocksize);
1294                 EXT4_I(inode)->i_extra_isize = new_extra_isize;
1295                 error = 0;
1296                 goto cleanup;
1297         }
1298
1299         /*
1300          * Enough free space isn't available in the inode, check if
1301          * EA block can hold new_extra_isize bytes.
1302          */
1303         if (EXT4_I(inode)->i_file_acl) {
1304                 bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1305                 error = -EIO;
1306                 if (!bh)
1307                         goto cleanup;
1308                 if (ext4_xattr_check_block(inode, bh)) {
1309                         EXT4_ERROR_INODE(inode, "bad block %llu",
1310                                          EXT4_I(inode)->i_file_acl);
1311                         error = -EIO;
1312                         goto cleanup;
1313                 }
1314                 base = BHDR(bh);
1315                 first = BFIRST(bh);
1316                 end = bh->b_data + bh->b_size;
1317                 min_offs = end - base;
1318                 free = ext4_xattr_free_space(first, &min_offs, base, NULL);
1319                 if (free < new_extra_isize) {
1320                         if (!tried_min_extra_isize && s_min_extra_isize) {
1321                                 tried_min_extra_isize++;
1322                                 new_extra_isize = s_min_extra_isize;
1323                                 brelse(bh);
1324                                 goto retry;
1325                         }
1326                         error = -1;
1327                         goto cleanup;
1328                 }
1329         } else {
1330                 free = inode->i_sb->s_blocksize;
1331         }
1332
1333         while (new_extra_isize > 0) {
1334                 size_t offs, size, entry_size;
1335                 struct ext4_xattr_entry *small_entry = NULL;
1336                 struct ext4_xattr_info i = {
1337                         .value = NULL,
1338                         .value_len = 0,
1339                 };
1340                 unsigned int total_size;  /* EA entry size + value size */
1341                 unsigned int shift_bytes; /* No. of bytes to shift EAs by? */
1342                 unsigned int min_total_size = ~0U;
1343
1344                 is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
1345                 bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
1346                 if (!is || !bs) {
1347                         error = -ENOMEM;
1348                         goto cleanup;
1349                 }
1350
1351                 is->s.not_found = -ENODATA;
1352                 bs->s.not_found = -ENODATA;
1353                 is->iloc.bh = NULL;
1354                 bs->bh = NULL;
1355
1356                 last = IFIRST(header);
1357                 /* Find the entry best suited to be pushed into EA block */
1358                 entry = NULL;
1359                 for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1360                         total_size =
1361                         EXT4_XATTR_SIZE(le32_to_cpu(last->e_value_size)) +
1362                                         EXT4_XATTR_LEN(last->e_name_len);
1363                         if (total_size <= free && total_size < min_total_size) {
1364                                 if (total_size < new_extra_isize) {
1365                                         small_entry = last;
1366                                 } else {
1367                                         entry = last;
1368                                         min_total_size = total_size;
1369                                 }
1370                         }
1371                 }
1372
1373                 if (entry == NULL) {
1374                         if (small_entry) {
1375                                 entry = small_entry;
1376                         } else {
1377                                 if (!tried_min_extra_isize &&
1378                                     s_min_extra_isize) {
1379                                         tried_min_extra_isize++;
1380                                         new_extra_isize = s_min_extra_isize;
1381                                         kfree(is); is = NULL;
1382                                         kfree(bs); bs = NULL;
1383                                         brelse(bh);
1384                                         goto retry;
1385                                 }
1386                                 error = -1;
1387                                 goto cleanup;
1388                         }
1389                 }
1390                 offs = le16_to_cpu(entry->e_value_offs);
1391                 size = le32_to_cpu(entry->e_value_size);
1392                 entry_size = EXT4_XATTR_LEN(entry->e_name_len);
1393                 i.name_index = entry->e_name_index,
1394                 buffer = kmalloc(EXT4_XATTR_SIZE(size), GFP_NOFS);
1395                 b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
1396                 if (!buffer || !b_entry_name) {
1397                         error = -ENOMEM;
1398                         goto cleanup;
1399                 }
1400                 /* Save the entry name and the entry value */
1401                 memcpy(buffer, (void *)IFIRST(header) + offs,
1402                        EXT4_XATTR_SIZE(size));
1403                 memcpy(b_entry_name, entry->e_name, entry->e_name_len);
1404                 b_entry_name[entry->e_name_len] = '\0';
1405                 i.name = b_entry_name;
1406
1407                 error = ext4_get_inode_loc(inode, &is->iloc);
1408                 if (error)
1409                         goto cleanup;
1410
1411                 error = ext4_xattr_ibody_find(inode, &i, is);
1412                 if (error)
1413                         goto cleanup;
1414
1415                 /* Remove the chosen entry from the inode */
1416                 error = ext4_xattr_ibody_set(handle, inode, &i, is);
1417                 if (error)
1418                         goto cleanup;
1419
1420                 entry = IFIRST(header);
1421                 if (entry_size + EXT4_XATTR_SIZE(size) >= new_extra_isize)
1422                         shift_bytes = new_extra_isize;
1423                 else
1424                         shift_bytes = entry_size + size;
1425                 /* Adjust the offsets and shift the remaining entries ahead */
1426                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize -
1427                         shift_bytes, (void *)raw_inode +
1428                         EXT4_GOOD_OLD_INODE_SIZE + extra_isize + shift_bytes,
1429                         (void *)header, total_ino - entry_size,
1430                         inode->i_sb->s_blocksize);
1431
1432                 extra_isize += shift_bytes;
1433                 new_extra_isize -= shift_bytes;
1434                 EXT4_I(inode)->i_extra_isize = extra_isize;
1435
1436                 i.name = b_entry_name;
1437                 i.value = buffer;
1438                 i.value_len = size;
1439                 error = ext4_xattr_block_find(inode, &i, bs);
1440                 if (error)
1441                         goto cleanup;
1442
1443                 /* Add entry which was removed from the inode into the block */
1444                 error = ext4_xattr_block_set(handle, inode, &i, bs);
1445                 if (error)
1446                         goto cleanup;
1447                 kfree(b_entry_name);
1448                 kfree(buffer);
1449                 b_entry_name = NULL;
1450                 buffer = NULL;
1451                 brelse(is->iloc.bh);
1452                 kfree(is);
1453                 kfree(bs);
1454         }
1455         brelse(bh);
1456         up_write(&EXT4_I(inode)->xattr_sem);
1457         return 0;
1458
1459 cleanup:
1460         kfree(b_entry_name);
1461         kfree(buffer);
1462         if (is)
1463                 brelse(is->iloc.bh);
1464         kfree(is);
1465         kfree(bs);
1466         brelse(bh);
1467         up_write(&EXT4_I(inode)->xattr_sem);
1468         return error;
1469 }
1470
1471
1472
1473 /*
1474  * ext4_xattr_delete_inode()
1475  *
1476  * Free extended attribute resources associated with this inode. This
1477  * is called immediately before an inode is freed. We have exclusive
1478  * access to the inode.
1479  */
1480 void
1481 ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)
1482 {
1483         struct buffer_head *bh = NULL;
1484
1485         if (!EXT4_I(inode)->i_file_acl)
1486                 goto cleanup;
1487         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1488         if (!bh) {
1489                 EXT4_ERROR_INODE(inode, "block %llu read error",
1490                                  EXT4_I(inode)->i_file_acl);
1491                 goto cleanup;
1492         }
1493         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
1494             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1495                 EXT4_ERROR_INODE(inode, "bad block %llu",
1496                                  EXT4_I(inode)->i_file_acl);
1497                 goto cleanup;
1498         }
1499         ext4_xattr_release_block(handle, inode, bh);
1500         EXT4_I(inode)->i_file_acl = 0;
1501
1502 cleanup:
1503         brelse(bh);
1504 }
1505
1506 /*
1507  * ext4_xattr_put_super()
1508  *
1509  * This is called when a file system is unmounted.
1510  */
1511 void
1512 ext4_xattr_put_super(struct super_block *sb)
1513 {
1514         mb_cache_shrink(sb->s_bdev);
1515 }
1516
1517 /*
1518  * ext4_xattr_cache_insert()
1519  *
1520  * Create a new entry in the extended attribute cache, and insert
1521  * it unless such an entry is already in the cache.
1522  *
1523  * Returns 0, or a negative error number on failure.
1524  */
1525 static void
1526 ext4_xattr_cache_insert(struct mb_cache *ext4_mb_cache, struct buffer_head *bh)
1527 {
1528         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1529         struct mb_cache_entry *ce;
1530         int error;
1531
1532         ce = mb_cache_entry_alloc(ext4_mb_cache, GFP_NOFS);
1533         if (!ce) {
1534                 ea_bdebug(bh, "out of memory");
1535                 return;
1536         }
1537         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
1538         if (error) {
1539                 mb_cache_entry_free(ce);
1540                 if (error == -EBUSY) {
1541                         ea_bdebug(bh, "already in cache");
1542                         error = 0;
1543                 }
1544         } else {
1545                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1546                 mb_cache_entry_release(ce);
1547         }
1548 }
1549
1550 /*
1551  * ext4_xattr_cmp()
1552  *
1553  * Compare two extended attribute blocks for equality.
1554  *
1555  * Returns 0 if the blocks are equal, 1 if they differ, and
1556  * a negative error number on errors.
1557  */
1558 static int
1559 ext4_xattr_cmp(struct ext4_xattr_header *header1,
1560                struct ext4_xattr_header *header2)
1561 {
1562         struct ext4_xattr_entry *entry1, *entry2;
1563
1564         entry1 = ENTRY(header1+1);
1565         entry2 = ENTRY(header2+1);
1566         while (!IS_LAST_ENTRY(entry1)) {
1567                 if (IS_LAST_ENTRY(entry2))
1568                         return 1;
1569                 if (entry1->e_hash != entry2->e_hash ||
1570                     entry1->e_name_index != entry2->e_name_index ||
1571                     entry1->e_name_len != entry2->e_name_len ||
1572                     entry1->e_value_size != entry2->e_value_size ||
1573                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1574                         return 1;
1575                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1576                         return -EIO;
1577                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1578                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1579                            le32_to_cpu(entry1->e_value_size)))
1580                         return 1;
1581
1582                 entry1 = EXT4_XATTR_NEXT(entry1);
1583                 entry2 = EXT4_XATTR_NEXT(entry2);
1584         }
1585         if (!IS_LAST_ENTRY(entry2))
1586                 return 1;
1587         return 0;
1588 }
1589
1590 /*
1591  * ext4_xattr_cache_find()
1592  *
1593  * Find an identical extended attribute block.
1594  *
1595  * Returns a pointer to the block found, or NULL if such a block was
1596  * not found or an error occurred.
1597  */
1598 static struct buffer_head *
1599 ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
1600                       struct mb_cache_entry **pce)
1601 {
1602         __u32 hash = le32_to_cpu(header->h_hash);
1603         struct mb_cache_entry *ce;
1604         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
1605
1606         if (!header->h_hash)
1607                 return NULL;  /* never share */
1608         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1609 again:
1610         ce = mb_cache_entry_find_first(ext4_mb_cache, inode->i_sb->s_bdev,
1611                                        hash);
1612         while (ce) {
1613                 struct buffer_head *bh;
1614
1615                 if (IS_ERR(ce)) {
1616                         if (PTR_ERR(ce) == -EAGAIN)
1617                                 goto again;
1618                         break;
1619                 }
1620                 bh = sb_bread(inode->i_sb, ce->e_block);
1621                 if (!bh) {
1622                         EXT4_ERROR_INODE(inode, "block %lu read error",
1623                                          (unsigned long) ce->e_block);
1624                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1625                                 EXT4_XATTR_REFCOUNT_MAX) {
1626                         ea_idebug(inode, "block %lu refcount %d>=%d",
1627                                   (unsigned long) ce->e_block,
1628                                   le32_to_cpu(BHDR(bh)->h_refcount),
1629                                           EXT4_XATTR_REFCOUNT_MAX);
1630                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
1631                         *pce = ce;
1632                         return bh;
1633                 }
1634                 brelse(bh);
1635                 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
1636         }
1637         return NULL;
1638 }
1639
1640 #define NAME_HASH_SHIFT 5
1641 #define VALUE_HASH_SHIFT 16
1642
1643 /*
1644  * ext4_xattr_hash_entry()
1645  *
1646  * Compute the hash of an extended attribute.
1647  */
1648 static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
1649                                          struct ext4_xattr_entry *entry)
1650 {
1651         __u32 hash = 0;
1652         char *name = entry->e_name;
1653         int n;
1654
1655         for (n = 0; n < entry->e_name_len; n++) {
1656                 hash = (hash << NAME_HASH_SHIFT) ^
1657                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1658                        *name++;
1659         }
1660
1661         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1662                 __le32 *value = (__le32 *)((char *)header +
1663                         le16_to_cpu(entry->e_value_offs));
1664                 for (n = (le32_to_cpu(entry->e_value_size) +
1665                      EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {
1666                         hash = (hash << VALUE_HASH_SHIFT) ^
1667                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1668                                le32_to_cpu(*value++);
1669                 }
1670         }
1671         entry->e_hash = cpu_to_le32(hash);
1672 }
1673
1674 #undef NAME_HASH_SHIFT
1675 #undef VALUE_HASH_SHIFT
1676
1677 #define BLOCK_HASH_SHIFT 16
1678
1679 /*
1680  * ext4_xattr_rehash()
1681  *
1682  * Re-compute the extended attribute hash value after an entry has changed.
1683  */
1684 static void ext4_xattr_rehash(struct ext4_xattr_header *header,
1685                               struct ext4_xattr_entry *entry)
1686 {
1687         struct ext4_xattr_entry *here;
1688         __u32 hash = 0;
1689
1690         ext4_xattr_hash_entry(header, entry);
1691         here = ENTRY(header+1);
1692         while (!IS_LAST_ENTRY(here)) {
1693                 if (!here->e_hash) {
1694                         /* Block is not shared if an entry's hash value == 0 */
1695                         hash = 0;
1696                         break;
1697                 }
1698                 hash = (hash << BLOCK_HASH_SHIFT) ^
1699                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1700                        le32_to_cpu(here->e_hash);
1701                 here = EXT4_XATTR_NEXT(here);
1702         }
1703         header->h_hash = cpu_to_le32(hash);
1704 }
1705
1706 #undef BLOCK_HASH_SHIFT
1707
1708 #define HASH_BUCKET_BITS        10
1709
1710 struct mb_cache *
1711 ext4_xattr_create_cache(char *name)
1712 {
1713         return mb_cache_create(name, HASH_BUCKET_BITS);
1714 }
1715
1716 void ext4_xattr_destroy_cache(struct mb_cache *cache)
1717 {
1718         if (cache)
1719                 mb_cache_destroy(cache);
1720 }
1721