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                 printk(KERN_DEBUG "block %pg:%lu: ",               \
  72                        bh->b_bdev, (unsigned long) bh->b_blocknr); \
  73                 printk(f); \
  74                 printk("\n"); \
  75         } while (0)
  76 #else
  77 # define ea_idebug(inode, fmt, ...)     no_printk(fmt, ##__VA_ARGS__)
  78 # define ea_bdebug(bh, fmt, ...)        no_printk(fmt, ##__VA_ARGS__)
  79 #endif
  80
  81 static void ext4_xattr_cache_insert(struct mb_cache *, struct buffer_head *);
  82 static struct buffer_head *ext4_xattr_cache_find(struct inode *,
  83                                                  struct ext4_xattr_header *,
  84                                                  struct mb_cache_entry **);
  85 static void ext4_xattr_rehash(struct ext4_xattr_header *,
  86                               struct ext4_xattr_entry *);
  87 static int ext4_xattr_list(struct dentry *dentry, char *buffer,
  88                            size_t buffer_size);
  89
  90 static const struct xattr_handler *ext4_xattr_handler_map[] = {
  91         [EXT4_XATTR_INDEX_USER]              = &ext4_xattr_user_handler,
  92 #ifdef CONFIG_EXT4_FS_POSIX_ACL
  93         [EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &posix_acl_access_xattr_handler,
  94         [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
  95 #endif
  96         [EXT4_XATTR_INDEX_TRUSTED]           = &ext4_xattr_trusted_handler,
  97 #ifdef CONFIG_EXT4_FS_SECURITY
  98         [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
  99 #endif
 100 };
 101
 102 const struct xattr_handler *ext4_xattr_handlers[] = {
 103         &ext4_xattr_user_handler,
 104         &ext4_xattr_trusted_handler,
 105 #ifdef CONFIG_EXT4_FS_POSIX_ACL
 106         &posix_acl_access_xattr_handler,
 107         &posix_acl_default_xattr_handler,
 108 #endif
 109 #ifdef CONFIG_EXT4_FS_SECURITY
 110         &ext4_xattr_security_handler,
 111 #endif
 112         NULL
 113 };
 114
 115 #define EXT4_GET_MB_CACHE(inode)        (((struct ext4_sb_info *) \
 116                                 inode->i_sb->s_fs_info)->s_mb_cache)
 117
 118 static __le32 ext4_xattr_block_csum(struct inode *inode,
 119                                     sector_t block_nr,
 120                                     struct ext4_xattr_header *hdr)
 121 {
 122         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 123         __u32 csum;
 124         __le32 save_csum;
 125         __le64 dsk_block_nr = cpu_to_le64(block_nr);
 126
 127         save_csum = hdr->h_checksum;
 128         hdr->h_checksum = 0;
 129         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&dsk_block_nr,
 130                            sizeof(dsk_block_nr));
 131         csum = ext4_chksum(sbi, csum, (__u8 *)hdr,
 132                            EXT4_BLOCK_SIZE(inode->i_sb));
 133
 134         hdr->h_checksum = save_csum;
 135         return cpu_to_le32(csum);
 136 }
 137
 138 static int ext4_xattr_block_csum_verify(struct inode *inode,
 139                                         sector_t block_nr,
 140                                         struct ext4_xattr_header *hdr)
 141 {
 142         if (ext4_has_metadata_csum(inode->i_sb) &&
 143             (hdr->h_checksum != ext4_xattr_block_csum(inode, block_nr, hdr)))
 144                 return 0;
 145         return 1;
 146 }
 147
 148 static void ext4_xattr_block_csum_set(struct inode *inode,
 149                                       sector_t block_nr,
 150                                       struct ext4_xattr_header *hdr)
 151 {
 152         if (!ext4_has_metadata_csum(inode->i_sb))
 153                 return;
 154
 155         hdr->h_checksum = ext4_xattr_block_csum(inode, block_nr, hdr);
 156 }
 157
 158 static inline int ext4_handle_dirty_xattr_block(handle_t *handle,
 159                                                 struct inode *inode,
 160                                                 struct buffer_head *bh)
 161 {
 162         ext4_xattr_block_csum_set(inode, bh->b_blocknr, BHDR(bh));
 163         return ext4_handle_dirty_metadata(handle, inode, bh);
 164 }
 165
 166 static inline const struct xattr_handler *
 167 ext4_xattr_handler(int name_index)
 168 {
 169         const struct xattr_handler *handler = NULL;
 170
 171         if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
 172                 handler = ext4_xattr_handler_map[name_index];
 173         return handler;
 174 }
 175
 176 /*
 177  * Inode operation listxattr()
 178  *
 179  * d_inode(dentry)->i_mutex: don't care
 180  */
 181 ssize_t
 182 ext4_listxattr(struct dentry *dentry, char *buffer, size_t size)
 183 {
 184         return ext4_xattr_list(dentry, buffer, size);
 185 }
 186
 187 static int
 188 ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end,
 189                        void *value_start)
 190 {
 191         struct ext4_xattr_entry *e = entry;
 192
 193         while (!IS_LAST_ENTRY(e)) {
 194                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(e);
 195                 if ((void *)next >= end)
 196                         return -EFSCORRUPTED;
 197                 e = next;
 198         }
 199
 200         while (!IS_LAST_ENTRY(entry)) {
 201                 if (entry->e_value_size != 0 &&
 202                     (value_start + le16_to_cpu(entry->e_value_offs) <
 203                      (void *)e + sizeof(__u32) ||
 204                      value_start + le16_to_cpu(entry->e_value_offs) +
 205                     le32_to_cpu(entry->e_value_size) > end))
 206                         return -EFSCORRUPTED;
 207                 entry = EXT4_XATTR_NEXT(entry);
 208         }
 209
 210         return 0;
 211 }
 212
 213 static inline int
 214 ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh)
 215 {
 216         int error;
 217
 218         if (buffer_verified(bh))
 219                 return 0;
 220
 221         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
 222             BHDR(bh)->h_blocks != cpu_to_le32(1))
 223                 return -EFSCORRUPTED;
 224         if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh)))
 225                 return -EFSBADCRC;
 226         error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size,
 227                                        bh->b_data);
 228         if (!error)
 229                 set_buffer_verified(bh);
 230         return error;
 231 }
 232
 233 static int
 234 __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
 235                          void *end, const char *function, unsigned int line)
 236 {
 237         struct ext4_xattr_entry *entry = IFIRST(header);
 238         int error = -EFSCORRUPTED;
 239
 240         if (((void *) header >= end) ||
 241             (header->h_magic != le32_to_cpu(EXT4_XATTR_MAGIC)))
 242                 goto errout;
 243         error = ext4_xattr_check_names(entry, end, entry);
 244 errout:
 245         if (error)
 246                 __ext4_error_inode(inode, function, line, 0,
 247                                    "corrupted in-inode xattr");
 248         return error;
 249 }
 250
 251 #define xattr_check_inode(inode, header, end) \
 252         __xattr_check_inode((inode), (header), (end), __func__, __LINE__)
 253
 254 static inline int
 255 ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size)
 256 {
 257         size_t value_size = le32_to_cpu(entry->e_value_size);
 258
 259         if (entry->e_value_block != 0 || value_size > size ||
 260             le16_to_cpu(entry->e_value_offs) + value_size > size)
 261                 return -EFSCORRUPTED;
 262         return 0;
 263 }
 264
 265 static int
 266 ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
 267                       const char *name, size_t size, int sorted)
 268 {
 269         struct ext4_xattr_entry *entry;
 270         size_t name_len;
 271         int cmp = 1;
 272
 273         if (name == NULL)
 274                 return -EINVAL;
 275         name_len = strlen(name);
 276         entry = *pentry;
 277         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 278                 cmp = name_index - entry->e_name_index;
 279                 if (!cmp)
 280                         cmp = name_len - entry->e_name_len;
 281                 if (!cmp)
 282                         cmp = memcmp(name, entry->e_name, name_len);
 283                 if (cmp <= 0 && (sorted || cmp == 0))
 284                         break;
 285         }
 286         *pentry = entry;
 287         if (!cmp && ext4_xattr_check_entry(entry, size))
 288                 return -EFSCORRUPTED;
 289         return cmp ? -ENODATA : 0;
 290 }
 291
 292 static int
 293 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
 294                      void *buffer, size_t buffer_size)
 295 {
 296         struct buffer_head *bh = NULL;
 297         struct ext4_xattr_entry *entry;
 298         size_t size;
 299         int error;
 300         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 301
 302         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 303                   name_index, name, buffer, (long)buffer_size);
 304
 305         error = -ENODATA;
 306         if (!EXT4_I(inode)->i_file_acl)
 307                 goto cleanup;
 308         ea_idebug(inode, "reading block %llu",
 309                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 310         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 311         if (!bh)
 312                 goto cleanup;
 313         ea_bdebug(bh, "b_count=%d, refcount=%d",
 314                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 315         if (ext4_xattr_check_block(inode, bh)) {
 316 bad_block:
 317                 EXT4_ERROR_INODE(inode, "bad block %llu",
 318                                  EXT4_I(inode)->i_file_acl);
 319                 error = -EFSCORRUPTED;
 320                 goto cleanup;
 321         }
 322         ext4_xattr_cache_insert(ext4_mb_cache, bh);
 323         entry = BFIRST(bh);
 324         error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
 325         if (error == -EFSCORRUPTED)
 326                 goto bad_block;
 327         if (error)
 328                 goto cleanup;
 329         size = le32_to_cpu(entry->e_value_size);
 330         if (buffer) {
 331                 error = -ERANGE;
 332                 if (size > buffer_size)
 333                         goto cleanup;
 334                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
 335                        size);
 336         }
 337         error = size;
 338
 339 cleanup:
 340         brelse(bh);
 341         return error;
 342 }
 343
 344 int
 345 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 346                      void *buffer, size_t buffer_size)
 347 {
 348         struct ext4_xattr_ibody_header *header;
 349         struct ext4_xattr_entry *entry;
 350         struct ext4_inode *raw_inode;
 351         struct ext4_iloc iloc;
 352         size_t size;
 353         void *end;
 354         int error;
 355
 356         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 357                 return -ENODATA;
 358         error = ext4_get_inode_loc(inode, &iloc);
 359         if (error)
 360                 return error;
 361         raw_inode = ext4_raw_inode(&iloc);
 362         header = IHDR(inode, raw_inode);
 363         entry = IFIRST(header);
 364         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 365         error = xattr_check_inode(inode, header, end);
 366         if (error)
 367                 goto cleanup;
 368         error = ext4_xattr_find_entry(&entry, name_index, name,
 369                                       end - (void *)entry, 0);
 370         if (error)
 371                 goto cleanup;
 372         size = le32_to_cpu(entry->e_value_size);
 373         if (buffer) {
 374                 error = -ERANGE;
 375                 if (size > buffer_size)
 376                         goto cleanup;
 377                 memcpy(buffer, (void *)IFIRST(header) +
 378                        le16_to_cpu(entry->e_value_offs), size);
 379         }
 380         error = size;
 381
 382 cleanup:
 383         brelse(iloc.bh);
 384         return error;
 385 }
 386
 387 /*
 388  * ext4_xattr_get()
 389  *
 390  * Copy an extended attribute into the buffer
 391  * provided, or compute the buffer size required.
 392  * Buffer is NULL to compute the size of the buffer required.
 393  *
 394  * Returns a negative error number on failure, or the number of bytes
 395  * used / required on success.
 396  */
 397 int
 398 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
 399                void *buffer, size_t buffer_size)
 400 {
 401         int error;
 402
 403         if (strlen(name) > 255)
 404                 return -ERANGE;
 405
 406         down_read(&EXT4_I(inode)->xattr_sem);
 407         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
 408                                      buffer_size);
 409         if (error == -ENODATA)
 410                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
 411                                              buffer_size);
 412         up_read(&EXT4_I(inode)->xattr_sem);
 413         return error;
 414 }
 415
 416 static int
 417 ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,
 418                         char *buffer, size_t buffer_size)
 419 {
 420         size_t rest = buffer_size;
 421
 422         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 423                 const struct xattr_handler *handler =
 424                         ext4_xattr_handler(entry->e_name_index);
 425
 426                 if (handler && (!handler->list || handler->list(dentry))) {
 427                         const char *prefix = handler->prefix ?: handler->name;
 428                         size_t prefix_len = strlen(prefix);
 429                         size_t size = prefix_len + entry->e_name_len + 1;
 430
 431                         if (buffer) {
 432                                 if (size > rest)
 433                                         return -ERANGE;
 434                                 memcpy(buffer, prefix, prefix_len);
 435                                 buffer += prefix_len;
 436                                 memcpy(buffer, entry->e_name, entry->e_name_len);
 437                                 buffer += entry->e_name_len;
 438                                 *buffer++ = 0;
 439                         }
 440                         rest -= size;
 441                 }
 442         }
 443         return buffer_size - rest;  /* total size */
 444 }
 445
 446 static int
 447 ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 448 {
 449         struct inode *inode = d_inode(dentry);
 450         struct buffer_head *bh = NULL;
 451         int error;
 452         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 453
 454         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 455                   buffer, (long)buffer_size);
 456
 457         error = 0;
 458         if (!EXT4_I(inode)->i_file_acl)
 459                 goto cleanup;
 460         ea_idebug(inode, "reading block %llu",
 461                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 462         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 463         error = -EIO;
 464         if (!bh)
 465                 goto cleanup;
 466         ea_bdebug(bh, "b_count=%d, refcount=%d",
 467                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 468         if (ext4_xattr_check_block(inode, bh)) {
 469                 EXT4_ERROR_INODE(inode, "bad block %llu",
 470                                  EXT4_I(inode)->i_file_acl);
 471                 error = -EFSCORRUPTED;
 472                 goto cleanup;
 473         }
 474         ext4_xattr_cache_insert(ext4_mb_cache, bh);
 475         error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
 476
 477 cleanup:
 478         brelse(bh);
 479
 480         return error;
 481 }
 482
 483 static int
 484 ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 485 {
 486         struct inode *inode = d_inode(dentry);
 487         struct ext4_xattr_ibody_header *header;
 488         struct ext4_inode *raw_inode;
 489         struct ext4_iloc iloc;
 490         void *end;
 491         int error;
 492
 493         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 494                 return 0;
 495         error = ext4_get_inode_loc(inode, &iloc);
 496         if (error)
 497                 return error;
 498         raw_inode = ext4_raw_inode(&iloc);
 499         header = IHDR(inode, raw_inode);
 500         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 501         error = xattr_check_inode(inode, header, end);
 502         if (error)
 503                 goto cleanup;
 504         error = ext4_xattr_list_entries(dentry, IFIRST(header),
 505                                         buffer, buffer_size);
 506
 507 cleanup:
 508         brelse(iloc.bh);
 509         return error;
 510 }
 511
 512 /*
 513  * ext4_xattr_list()
 514  *
 515  * Copy a list of attribute names into the buffer
 516  * provided, or compute the buffer size required.
 517  * Buffer is NULL to compute the size of the buffer required.
 518  *
 519  * Returns a negative error number on failure, or the number of bytes
 520  * used / required on success.
 521  */
 522 static int
 523 ext4_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 524 {
 525         int ret, ret2;
 526
 527         down_read(&EXT4_I(d_inode(dentry))->xattr_sem);
 528         ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size);
 529         if (ret < 0)
 530                 goto errout;
 531         if (buffer) {
 532                 buffer += ret;
 533                 buffer_size -= ret;
 534         }
 535         ret = ext4_xattr_block_list(dentry, buffer, buffer_size);
 536         if (ret < 0)
 537                 goto errout;
 538         ret += ret2;
 539 errout:
 540         up_read(&EXT4_I(d_inode(dentry))->xattr_sem);
 541         return ret;
 542 }
 543
 544 /*
 545  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 546  * not set, set it.
 547  */
 548 static void ext4_xattr_update_super_block(handle_t *handle,
 549                                           struct super_block *sb)
 550 {
 551         if (ext4_has_feature_xattr(sb))
 552                 return;
 553
 554         BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
 555         if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
 556                 ext4_set_feature_xattr(sb);
 557                 ext4_handle_dirty_super(handle, sb);
 558         }
 559 }
 560
 561 /*
 562  * Release the xattr block BH: If the reference count is > 1, decrement it;
 563  * otherwise free the block.
 564  */
 565 static void
 566 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
 567                          struct buffer_head *bh)
 568 {
 569         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 570         u32 hash, ref;
 571         int error = 0;
 572
 573         BUFFER_TRACE(bh, "get_write_access");
 574         error = ext4_journal_get_write_access(handle, bh);
 575         if (error)
 576                 goto out;
 577
 578         lock_buffer(bh);
 579         hash = le32_to_cpu(BHDR(bh)->h_hash);
 580         ref = le32_to_cpu(BHDR(bh)->h_refcount);
 581         if (ref == 1) {
 582                 ea_bdebug(bh, "refcount now=0; freeing");
 583                 /*
 584                  * This must happen under buffer lock for
 585                  * ext4_xattr_block_set() to reliably detect freed block
 586                  */
 587                 mb_cache_entry_delete_block(ext4_mb_cache, hash, bh->b_blocknr);
 588                 get_bh(bh);
 589                 unlock_buffer(bh);
 590                 ext4_free_blocks(handle, inode, bh, 0, 1,
 591                                  EXT4_FREE_BLOCKS_METADATA |
 592                                  EXT4_FREE_BLOCKS_FORGET);
 593         } else {
 594                 ref--;
 595                 BHDR(bh)->h_refcount = cpu_to_le32(ref);
 596                 if (ref == EXT4_XATTR_REFCOUNT_MAX - 1) {
 597                         struct mb_cache_entry *ce;
 598
 599                         ce = mb_cache_entry_get(ext4_mb_cache, hash,
 600                                                 bh->b_blocknr);
 601                         if (ce) {
 602                                 ce->e_reusable = 1;
 603                                 mb_cache_entry_put(ext4_mb_cache, ce);
 604                         }
 605                 }
 606
 607                 /*
 608                  * Beware of this ugliness: Releasing of xattr block references
 609                  * from different inodes can race and so we have to protect
 610                  * from a race where someone else frees the block (and releases
 611                  * its journal_head) before we are done dirtying the buffer. In
 612                  * nojournal mode this race is harmless and we actually cannot
 613                  * call ext4_handle_dirty_xattr_block() with locked buffer as
 614                  * that function can call sync_dirty_buffer() so for that case
 615                  * we handle the dirtying after unlocking the buffer.
 616                  */
 617                 if (ext4_handle_valid(handle))
 618                         error = ext4_handle_dirty_xattr_block(handle, inode,
 619                                                               bh);
 620                 unlock_buffer(bh);
 621                 if (!ext4_handle_valid(handle))
 622                         error = ext4_handle_dirty_xattr_block(handle, inode,
 623                                                               bh);
 624                 if (IS_SYNC(inode))
 625                         ext4_handle_sync(handle);
 626                 dquot_free_block(inode, EXT4_C2B(EXT4_SB(inode->i_sb), 1));
 627                 ea_bdebug(bh, "refcount now=%d; releasing",
 628                           le32_to_cpu(BHDR(bh)->h_refcount));
 629         }
 630 out:
 631         ext4_std_error(inode->i_sb, error);
 632         return;
 633 }
 634
 635 /*
 636  * Find the available free space for EAs. This also returns the total number of
 637  * bytes used by EA entries.
 638  */
 639 static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
 640                                     size_t *min_offs, void *base, int *total)
 641 {
 642         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 643                 if (!last->e_value_block && last->e_value_size) {
 644                         size_t offs = le16_to_cpu(last->e_value_offs);
 645                         if (offs < *min_offs)
 646                                 *min_offs = offs;
 647                 }
 648                 if (total)
 649                         *total += EXT4_XATTR_LEN(last->e_name_len);
 650         }
 651         return (*min_offs - ((void *)last - base) - sizeof(__u32));
 652 }
 653
 654 static int
 655 ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
 656 {
 657         struct ext4_xattr_entry *last;
 658         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
 659
 660         /* Compute min_offs and last. */
 661         last = s->first;
 662         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 663                 if (!last->e_value_block && last->e_value_size) {
 664                         size_t offs = le16_to_cpu(last->e_value_offs);
 665                         if (offs < min_offs)
 666                                 min_offs = offs;
 667                 }
 668         }
 669         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
 670         if (!s->not_found) {
 671                 if (!s->here->e_value_block && s->here->e_value_size) {
 672                         size_t size = le32_to_cpu(s->here->e_value_size);
 673                         free += EXT4_XATTR_SIZE(size);
 674                 }
 675                 free += EXT4_XATTR_LEN(name_len);
 676         }
 677         if (i->value) {
 678                 if (free < EXT4_XATTR_LEN(name_len) +
 679                            EXT4_XATTR_SIZE(i->value_len))
 680                         return -ENOSPC;
 681         }
 682
 683         if (i->value && s->not_found) {
 684                 /* Insert the new name. */
 685                 size_t size = EXT4_XATTR_LEN(name_len);
 686                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
 687                 memmove((void *)s->here + size, s->here, rest);
 688                 memset(s->here, 0, size);
 689                 s->here->e_name_index = i->name_index;
 690                 s->here->e_name_len = name_len;
 691                 memcpy(s->here->e_name, i->name, name_len);
 692         } else {
 693                 if (!s->here->e_value_block && s->here->e_value_size) {
 694                         void *first_val = s->base + min_offs;
 695                         size_t offs = le16_to_cpu(s->here->e_value_offs);
 696                         void *val = s->base + offs;
 697                         size_t size = EXT4_XATTR_SIZE(
 698                                 le32_to_cpu(s->here->e_value_size));
 699
 700                         if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
 701                                 /* The old and the new value have the same
 702                                    size. Just replace. */
 703                                 s->here->e_value_size =
 704                                         cpu_to_le32(i->value_len);
 705                                 if (i->value == EXT4_ZERO_XATTR_VALUE) {
 706                                         memset(val, 0, size);
 707                                 } else {
 708                                         /* Clear pad bytes first. */
 709                                         memset(val + size - EXT4_XATTR_PAD, 0,
 710                                                EXT4_XATTR_PAD);
 711                                         memcpy(val, i->value, i->value_len);
 712                                 }
 713                                 return 0;
 714                         }
 715
 716                         /* Remove the old value. */
 717                         memmove(first_val + size, first_val, val - first_val);
 718                         memset(first_val, 0, size);
 719                         s->here->e_value_size = 0;
 720                         s->here->e_value_offs = 0;
 721                         min_offs += size;
 722
 723                         /* Adjust all value offsets. */
 724                         last = s->first;
 725                         while (!IS_LAST_ENTRY(last)) {
 726                                 size_t o = le16_to_cpu(last->e_value_offs);
 727                                 if (!last->e_value_block &&
 728                                     last->e_value_size && o < offs)
 729                                         last->e_value_offs =
 730                                                 cpu_to_le16(o + size);
 731                                 last = EXT4_XATTR_NEXT(last);
 732                         }
 733                 }
 734                 if (!i->value) {
 735                         /* Remove the old name. */
 736                         size_t size = EXT4_XATTR_LEN(name_len);
 737                         last = ENTRY((void *)last - size);
 738                         memmove(s->here, (void *)s->here + size,
 739                                 (void *)last - (void *)s->here + sizeof(__u32));
 740                         memset(last, 0, size);
 741                 }
 742         }
 743
 744         if (i->value) {
 745                 /* Insert the new value. */
 746                 s->here->e_value_size = cpu_to_le32(i->value_len);
 747                 if (i->value_len) {
 748                         size_t size = EXT4_XATTR_SIZE(i->value_len);
 749                         void *val = s->base + min_offs - size;
 750                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
 751                         if (i->value == EXT4_ZERO_XATTR_VALUE) {
 752                                 memset(val, 0, size);
 753                         } else {
 754                                 /* Clear the pad bytes first. */
 755                                 memset(val + size - EXT4_XATTR_PAD, 0,
 756                                        EXT4_XATTR_PAD);
 757                                 memcpy(val, i->value, i->value_len);
 758                         }
 759                 }
 760         }
 761         return 0;
 762 }
 763
 764 struct ext4_xattr_block_find {
 765         struct ext4_xattr_search s;
 766         struct buffer_head *bh;
 767 };
 768
 769 static int
 770 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
 771                       struct ext4_xattr_block_find *bs)
 772 {
 773         struct super_block *sb = inode->i_sb;
 774         int error;
 775
 776         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
 777                   i->name_index, i->name, i->value, (long)i->value_len);
 778
 779         if (EXT4_I(inode)->i_file_acl) {
 780                 /* The inode already has an extended attribute block. */
 781                 bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);
 782                 error = -EIO;
 783                 if (!bs->bh)
 784                         goto cleanup;
 785                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
 786                         atomic_read(&(bs->bh->b_count)),
 787                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
 788                 if (ext4_xattr_check_block(inode, bs->bh)) {
 789                         EXT4_ERROR_INODE(inode, "bad block %llu",
 790                                          EXT4_I(inode)->i_file_acl);
 791                         error = -EFSCORRUPTED;
 792                         goto cleanup;
 793                 }
 794                 /* Find the named attribute. */
 795                 bs->s.base = BHDR(bs->bh);
 796                 bs->s.first = BFIRST(bs->bh);
 797                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
 798                 bs->s.here = bs->s.first;
 799                 error = ext4_xattr_find_entry(&bs->s.here, i->name_index,
 800                                               i->name, bs->bh->b_size, 1);
 801                 if (error && error != -ENODATA)
 802                         goto cleanup;
 803                 bs->s.not_found = error;
 804         }
 805         error = 0;
 806
 807 cleanup:
 808         return error;
 809 }
 810
 811 static int
 812 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
 813                      struct ext4_xattr_info *i,
 814                      struct ext4_xattr_block_find *bs)
 815 {
 816         struct super_block *sb = inode->i_sb;
 817         struct buffer_head *new_bh = NULL;
 818         struct ext4_xattr_search *s = &bs->s;
 819         struct mb_cache_entry *ce = NULL;
 820         int error = 0;
 821         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 822
 823 #define header(x) ((struct ext4_xattr_header *)(x))
 824
 825         if (i->value && i->value_len > sb->s_blocksize)
 826                 return -ENOSPC;
 827         if (s->base) {
 828                 BUFFER_TRACE(bs->bh, "get_write_access");
 829                 error = ext4_journal_get_write_access(handle, bs->bh);
 830                 if (error)
 831                         goto cleanup;
 832                 lock_buffer(bs->bh);
 833
 834                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 835                         __u32 hash = le32_to_cpu(BHDR(bs->bh)->h_hash);
 836
 837                         /*
 838                          * This must happen under buffer lock for
 839                          * ext4_xattr_block_set() to reliably detect modified
 840                          * block
 841                          */
 842                         mb_cache_entry_delete_block(ext4_mb_cache, hash,
 843                                                     bs->bh->b_blocknr);
 844                         ea_bdebug(bs->bh, "modifying in-place");
 845                         error = ext4_xattr_set_entry(i, s);
 846                         if (!error) {
 847                                 if (!IS_LAST_ENTRY(s->first))
 848                                         ext4_xattr_rehash(header(s->base),
 849                                                           s->here);
 850                                 ext4_xattr_cache_insert(ext4_mb_cache,
 851                                         bs->bh);
 852                         }
 853                         unlock_buffer(bs->bh);
 854                         if (error == -EFSCORRUPTED)
 855                                 goto bad_block;
 856                         if (!error)
 857                                 error = ext4_handle_dirty_xattr_block(handle,
 858                                                                       inode,
 859                                                                       bs->bh);
 860                         if (error)
 861                                 goto cleanup;
 862                         goto inserted;
 863                 } else {
 864                         int offset = (char *)s->here - bs->bh->b_data;
 865
 866                         unlock_buffer(bs->bh);
 867                         ea_bdebug(bs->bh, "cloning");
 868                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
 869                         error = -ENOMEM;
 870                         if (s->base == NULL)
 871                                 goto cleanup;
 872                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 873                         s->first = ENTRY(header(s->base)+1);
 874                         header(s->base)->h_refcount = cpu_to_le32(1);
 875                         s->here = ENTRY(s->base + offset);
 876                         s->end = s->base + bs->bh->b_size;
 877                 }
 878         } else {
 879                 /* Allocate a buffer where we construct the new block. */
 880                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
 881                 /* assert(header == s->base) */
 882                 error = -ENOMEM;
 883                 if (s->base == NULL)
 884                         goto cleanup;
 885                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
 886                 header(s->base)->h_blocks = cpu_to_le32(1);
 887                 header(s->base)->h_refcount = cpu_to_le32(1);
 888                 s->first = ENTRY(header(s->base)+1);
 889                 s->here = ENTRY(header(s->base)+1);
 890                 s->end = s->base + sb->s_blocksize;
 891         }
 892
 893         error = ext4_xattr_set_entry(i, s);
 894         if (error == -EFSCORRUPTED)
 895                 goto bad_block;
 896         if (error)
 897                 goto cleanup;
 898         if (!IS_LAST_ENTRY(s->first))
 899                 ext4_xattr_rehash(header(s->base), s->here);
 900
 901 inserted:
 902         if (!IS_LAST_ENTRY(s->first)) {
 903                 new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);
 904                 if (new_bh) {
 905                         /* We found an identical block in the cache. */
 906                         if (new_bh == bs->bh)
 907                                 ea_bdebug(new_bh, "keeping");
 908                         else {
 909                                 u32 ref;
 910
 911                                 /* The old block is released after updating
 912                                    the inode. */
 913                                 error = dquot_alloc_block(inode,
 914                                                 EXT4_C2B(EXT4_SB(sb), 1));
 915                                 if (error)
 916                                         goto cleanup;
 917                                 BUFFER_TRACE(new_bh, "get_write_access");
 918                                 error = ext4_journal_get_write_access(handle,
 919                                                                       new_bh);
 920                                 if (error)
 921                                         goto cleanup_dquot;
 922                                 lock_buffer(new_bh);
 923                                 /*
 924                                  * We have to be careful about races with
 925                                  * freeing, rehashing or adding references to
 926                                  * xattr block. Once we hold buffer lock xattr
 927                                  * block's state is stable so we can check
 928                                  * whether the block got freed / rehashed or
 929                                  * not.  Since we unhash mbcache entry under
 930                                  * buffer lock when freeing / rehashing xattr
 931                                  * block, checking whether entry is still
 932                                  * hashed is reliable. Same rules hold for
 933                                  * e_reusable handling.
 934                                  */
 935                                 if (hlist_bl_unhashed(&ce->e_hash_list) ||
 936                                     !ce->e_reusable) {
 937                                         /*
 938                                          * Undo everything and check mbcache
 939                                          * again.
 940                                          */
 941                                         unlock_buffer(new_bh);
 942                                         dquot_free_block(inode,
 943                                                          EXT4_C2B(EXT4_SB(sb),
 944                                                                   1));
 945                                         brelse(new_bh);
 946                                         mb_cache_entry_put(ext4_mb_cache, ce);
 947                                         ce = NULL;
 948                                         new_bh = NULL;
 949                                         goto inserted;
 950                                 }
 951                                 ref = le32_to_cpu(BHDR(new_bh)->h_refcount) + 1;
 952                                 BHDR(new_bh)->h_refcount = cpu_to_le32(ref);
 953                                 if (ref >= EXT4_XATTR_REFCOUNT_MAX)
 954                                         ce->e_reusable = 0;
 955                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
 956                                           ref);
 957                                 unlock_buffer(new_bh);
 958                                 error = ext4_handle_dirty_xattr_block(handle,
 959                                                                       inode,
 960                                                                       new_bh);
 961                                 if (error)
 962                                         goto cleanup_dquot;
 963                         }
 964                         mb_cache_entry_touch(ext4_mb_cache, ce);
 965                         mb_cache_entry_put(ext4_mb_cache, ce);
 966                         ce = NULL;
 967                 } else if (bs->bh && s->base == bs->bh->b_data) {
 968                         /* We were modifying this block in-place. */
 969                         ea_bdebug(bs->bh, "keeping this block");
 970                         new_bh = bs->bh;
 971                         get_bh(new_bh);
 972                 } else {
 973                         /* We need to allocate a new block */
 974                         ext4_fsblk_t goal, block;
 975
 976                         goal = ext4_group_first_block_no(sb,
 977                                                 EXT4_I(inode)->i_block_group);
 978
 979                         /* non-extent files can't have physical blocks past 2^32 */
 980                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 981                                 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
 982
 983                         block = ext4_new_meta_blocks(handle, inode, goal, 0,
 984                                                      NULL, &error);
 985                         if (error)
 986                                 goto cleanup;
 987
 988                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 989                                 BUG_ON(block > EXT4_MAX_BLOCK_FILE_PHYS);
 990
 991                         ea_idebug(inode, "creating block %llu",
 992                                   (unsigned long long)block);
 993
 994                         new_bh = sb_getblk(sb, block);
 995                         if (unlikely(!new_bh)) {
 996                                 error = -ENOMEM;
 997 getblk_failed:
 998                                 ext4_free_blocks(handle, inode, NULL, block, 1,
 999                                                  EXT4_FREE_BLOCKS_METADATA);
1000                                 goto cleanup;
1001                         }
1002                         lock_buffer(new_bh);
1003                         error = ext4_journal_get_create_access(handle, new_bh);
1004                         if (error) {
1005                                 unlock_buffer(new_bh);
1006                                 error = -EIO;
1007                                 goto getblk_failed;
1008                         }
1009                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
1010                         set_buffer_uptodate(new_bh);
1011                         unlock_buffer(new_bh);
1012                         ext4_xattr_cache_insert(ext4_mb_cache, new_bh);
1013                         error = ext4_handle_dirty_xattr_block(handle,
1014                                                               inode, new_bh);
1015                         if (error)
1016                                 goto cleanup;
1017                 }
1018         }
1019
1020         /* Update the inode. */
1021         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
1022
1023         /* Drop the previous xattr block. */
1024         if (bs->bh && bs->bh != new_bh)
1025                 ext4_xattr_release_block(handle, inode, bs->bh);
1026         error = 0;
1027
1028 cleanup:
1029         if (ce)
1030                 mb_cache_entry_put(ext4_mb_cache, ce);
1031         brelse(new_bh);
1032         if (!(bs->bh && s->base == bs->bh->b_data))
1033                 kfree(s->base);
1034
1035         return error;
1036
1037 cleanup_dquot:
1038         dquot_free_block(inode, EXT4_C2B(EXT4_SB(sb), 1));
1039         goto cleanup;
1040
1041 bad_block:
1042         EXT4_ERROR_INODE(inode, "bad block %llu",
1043                          EXT4_I(inode)->i_file_acl);
1044         goto cleanup;
1045
1046 #undef header
1047 }
1048
1049 int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
1050                           struct ext4_xattr_ibody_find *is)
1051 {
1052         struct ext4_xattr_ibody_header *header;
1053         struct ext4_inode *raw_inode;
1054         int error;
1055
1056         if (EXT4_I(inode)->i_extra_isize == 0)
1057                 return 0;
1058         raw_inode = ext4_raw_inode(&is->iloc);
1059         header = IHDR(inode, raw_inode);
1060         is->s.base = is->s.first = IFIRST(header);
1061         is->s.here = is->s.first;
1062         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
1063         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
1064                 error = xattr_check_inode(inode, header, is->s.end);
1065                 if (error)
1066                         return error;
1067                 /* Find the named attribute. */
1068                 error = ext4_xattr_find_entry(&is->s.here, i->name_index,
1069                                               i->name, is->s.end -
1070                                               (void *)is->s.base, 0);
1071                 if (error && error != -ENODATA)
1072                         return error;
1073                 is->s.not_found = error;
1074         }
1075         return 0;
1076 }
1077
1078 int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode,
1079                                 struct ext4_xattr_info *i,
1080                                 struct ext4_xattr_ibody_find *is)
1081 {
1082         struct ext4_xattr_ibody_header *header;
1083         struct ext4_xattr_search *s = &is->s;
1084         int error;
1085
1086         if (EXT4_I(inode)->i_extra_isize == 0)
1087                 return -ENOSPC;
1088         error = ext4_xattr_set_entry(i, s);
1089         if (error) {
1090                 if (error == -ENOSPC &&
1091                     ext4_has_inline_data(inode)) {
1092                         error = ext4_try_to_evict_inline_data(handle, inode,
1093                                         EXT4_XATTR_LEN(strlen(i->name) +
1094                                         EXT4_XATTR_SIZE(i->value_len)));
1095                         if (error)
1096                                 return error;
1097                         error = ext4_xattr_ibody_find(inode, i, is);
1098                         if (error)
1099                                 return error;
1100                         error = ext4_xattr_set_entry(i, s);
1101                 }
1102                 if (error)
1103                         return error;
1104         }
1105         header = IHDR(inode, ext4_raw_inode(&is->iloc));
1106         if (!IS_LAST_ENTRY(s->first)) {
1107                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1108                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
1109         } else {
1110                 header->h_magic = cpu_to_le32(0);
1111                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
1112         }
1113         return 0;
1114 }
1115
1116 static int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
1117                                 struct ext4_xattr_info *i,
1118                                 struct ext4_xattr_ibody_find *is)
1119 {
1120         struct ext4_xattr_ibody_header *header;
1121         struct ext4_xattr_search *s = &is->s;
1122         int error;
1123
1124         if (EXT4_I(inode)->i_extra_isize == 0)
1125                 return -ENOSPC;
1126         error = ext4_xattr_set_entry(i, s);
1127         if (error)
1128                 return error;
1129         header = IHDR(inode, ext4_raw_inode(&is->iloc));
1130         if (!IS_LAST_ENTRY(s->first)) {
1131                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1132                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
1133         } else {
1134                 header->h_magic = cpu_to_le32(0);
1135                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
1136         }
1137         return 0;
1138 }
1139
1140 static int ext4_xattr_value_same(struct ext4_xattr_search *s,
1141                                  struct ext4_xattr_info *i)
1142 {
1143         void *value;
1144
1145         if (le32_to_cpu(s->here->e_value_size) != i->value_len)
1146                 return 0;
1147         value = ((void *)s->base) + le16_to_cpu(s->here->e_value_offs);
1148         return !memcmp(value, i->value, i->value_len);
1149 }
1150
1151 /*
1152  * ext4_xattr_set_handle()
1153  *
1154  * Create, replace or remove an extended attribute for this inode.  Value
1155  * is NULL to remove an existing extended attribute, and non-NULL to
1156  * either replace an existing extended attribute, or create a new extended
1157  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
1158  * specify that an extended attribute must exist and must not exist
1159  * previous to the call, respectively.
1160  *
1161  * Returns 0, or a negative error number on failure.
1162  */
1163 int
1164 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
1165                       const char *name, const void *value, size_t value_len,
1166                       int flags)
1167 {
1168         struct ext4_xattr_info i = {
1169                 .name_index = name_index,
1170                 .name = name,
1171                 .value = value,
1172                 .value_len = value_len,
1173
1174         };
1175         struct ext4_xattr_ibody_find is = {
1176                 .s = { .not_found = -ENODATA, },
1177         };
1178         struct ext4_xattr_block_find bs = {
1179                 .s = { .not_found = -ENODATA, },
1180         };
1181         unsigned long no_expand;
1182         int error;
1183
1184         if (!name)
1185                 return -EINVAL;
1186         if (strlen(name) > 255)
1187                 return -ERANGE;
1188         down_write(&EXT4_I(inode)->xattr_sem);
1189         no_expand = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
1190         ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
1191
1192         error = ext4_reserve_inode_write(handle, inode, &is.iloc);
1193         if (error)
1194                 goto cleanup;
1195
1196         if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) {
1197                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
1198                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
1199                 ext4_clear_inode_state(inode, EXT4_STATE_NEW);
1200         }
1201
1202         error = ext4_xattr_ibody_find(inode, &i, &is);
1203         if (error)
1204                 goto cleanup;
1205         if (is.s.not_found)
1206                 error = ext4_xattr_block_find(inode, &i, &bs);
1207         if (error)
1208                 goto cleanup;
1209         if (is.s.not_found && bs.s.not_found) {
1210                 error = -ENODATA;
1211                 if (flags & XATTR_REPLACE)
1212                         goto cleanup;
1213                 error = 0;
1214                 if (!value)
1215                         goto cleanup;
1216         } else {
1217                 error = -EEXIST;
1218                 if (flags & XATTR_CREATE)
1219                         goto cleanup;
1220         }
1221         if (!value) {
1222                 if (!is.s.not_found)
1223                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1224                 else if (!bs.s.not_found)
1225                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1226         } else {
1227                 error = 0;
1228                 /* Xattr value did not change? Save us some work and bail out */
1229                 if (!is.s.not_found && ext4_xattr_value_same(&is.s, &i))
1230                         goto cleanup;
1231                 if (!bs.s.not_found && ext4_xattr_value_same(&bs.s, &i))
1232                         goto cleanup;
1233
1234                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1235                 if (!error && !bs.s.not_found) {
1236                         i.value = NULL;
1237                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1238                 } else if (error == -ENOSPC) {
1239                         if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
1240                                 error = ext4_xattr_block_find(inode, &i, &bs);
1241                                 if (error)
1242                                         goto cleanup;
1243                         }
1244                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1245                         if (error)
1246                                 goto cleanup;
1247                         if (!is.s.not_found) {
1248                                 i.value = NULL;
1249                                 error = ext4_xattr_ibody_set(handle, inode, &i,
1250                                                              &is);
1251                         }
1252                 }
1253         }
1254         if (!error) {
1255                 ext4_xattr_update_super_block(handle, inode->i_sb);
1256                 inode->i_ctime = ext4_current_time(inode);
1257                 if (!value)
1258                         ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1259                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
1260                 /*
1261                  * The bh is consumed by ext4_mark_iloc_dirty, even with
1262                  * error != 0.
1263                  */
1264                 is.iloc.bh = NULL;
1265                 if (IS_SYNC(inode))
1266                         ext4_handle_sync(handle);
1267         }
1268
1269 cleanup:
1270         brelse(is.iloc.bh);
1271         brelse(bs.bh);
1272         if (no_expand == 0)
1273                 ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1274         up_write(&EXT4_I(inode)->xattr_sem);
1275         return error;
1276 }
1277
1278 /*
1279  * ext4_xattr_set()
1280  *
1281  * Like ext4_xattr_set_handle, but start from an inode. This extended
1282  * attribute modification is a filesystem transaction by itself.
1283  *
1284  * Returns 0, or a negative error number on failure.
1285  */
1286 int
1287 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
1288                const void *value, size_t value_len, int flags)
1289 {
1290         handle_t *handle;
1291         int error, retries = 0;
1292         int credits = ext4_jbd2_credits_xattr(inode);
1293
1294 retry:
1295         handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
1296         if (IS_ERR(handle)) {
1297                 error = PTR_ERR(handle);
1298         } else {
1299                 int error2;
1300
1301                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
1302                                               value, value_len, flags);
1303                 error2 = ext4_journal_stop(handle);
1304                 if (error == -ENOSPC &&
1305                     ext4_should_retry_alloc(inode->i_sb, &retries))
1306                         goto retry;
1307                 if (error == 0)
1308                         error = error2;
1309         }
1310
1311         return error;
1312 }
1313
1314 /*
1315  * Shift the EA entries in the inode to create space for the increased
1316  * i_extra_isize.
1317  */
1318 static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
1319                                      int value_offs_shift, void *to,
1320                                      void *from, size_t n, int blocksize)
1321 {
1322         struct ext4_xattr_entry *last = entry;
1323         int new_offs;
1324
1325         /* Adjust the value offsets of the entries */
1326         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1327                 if (!last->e_value_block && last->e_value_size) {
1328                         new_offs = le16_to_cpu(last->e_value_offs) +
1329                                                         value_offs_shift;
1330                         BUG_ON(new_offs + le32_to_cpu(last->e_value_size)
1331                                  > blocksize);
1332                         last->e_value_offs = cpu_to_le16(new_offs);
1333                 }
1334         }
1335         /* Shift the entries by n bytes */
1336         memmove(to, from, n);
1337 }
1338
1339 /*
1340  * Expand an inode by new_extra_isize bytes when EAs are present.
1341  * Returns 0 on success or negative error number on failure.
1342  */
1343 int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
1344                                struct ext4_inode *raw_inode, handle_t *handle)
1345 {
1346         struct ext4_xattr_ibody_header *header;
1347         struct ext4_xattr_entry *entry, *last, *first;
1348         struct buffer_head *bh = NULL;
1349         struct ext4_xattr_ibody_find *is = NULL;
1350         struct ext4_xattr_block_find *bs = NULL;
1351         char *buffer = NULL, *b_entry_name = NULL;
1352         size_t min_offs, free;
1353         int total_ino;
1354         void *base, *start, *end;
1355         int extra_isize = 0, error = 0, tried_min_extra_isize = 0;
1356         int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize);
1357
1358         down_write(&EXT4_I(inode)->xattr_sem);
1359 retry:
1360         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize) {
1361                 up_write(&EXT4_I(inode)->xattr_sem);
1362                 return 0;
1363         }
1364
1365         header = IHDR(inode, raw_inode);
1366         entry = IFIRST(header);
1367
1368         /*
1369          * Check if enough free space is available in the inode to shift the
1370          * entries ahead by new_extra_isize.
1371          */
1372
1373         base = start = entry;
1374         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
1375         min_offs = end - base;
1376         last = entry;
1377         total_ino = sizeof(struct ext4_xattr_ibody_header);
1378
1379         error = xattr_check_inode(inode, header, end);
1380         if (error)
1381                 goto cleanup;
1382
1383         free = ext4_xattr_free_space(last, &min_offs, base, &total_ino);
1384         if (free >= new_extra_isize) {
1385                 entry = IFIRST(header);
1386                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize
1387                                 - new_extra_isize, (void *)raw_inode +
1388                                 EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
1389                                 (void *)header, total_ino,
1390                                 inode->i_sb->s_blocksize);
1391                 EXT4_I(inode)->i_extra_isize = new_extra_isize;
1392                 error = 0;
1393                 goto cleanup;
1394         }
1395
1396         /*
1397          * Enough free space isn't available in the inode, check if
1398          * EA block can hold new_extra_isize bytes.
1399          */
1400         if (EXT4_I(inode)->i_file_acl) {
1401                 bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1402                 error = -EIO;
1403                 if (!bh)
1404                         goto cleanup;
1405                 if (ext4_xattr_check_block(inode, bh)) {
1406                         EXT4_ERROR_INODE(inode, "bad block %llu",
1407                                          EXT4_I(inode)->i_file_acl);
1408                         error = -EFSCORRUPTED;
1409                         goto cleanup;
1410                 }
1411                 base = BHDR(bh);
1412                 first = BFIRST(bh);
1413                 end = bh->b_data + bh->b_size;
1414                 min_offs = end - base;
1415                 free = ext4_xattr_free_space(first, &min_offs, base, NULL);
1416                 if (free < new_extra_isize) {
1417                         if (!tried_min_extra_isize && s_min_extra_isize) {
1418                                 tried_min_extra_isize++;
1419                                 new_extra_isize = s_min_extra_isize;
1420                                 brelse(bh);
1421                                 goto retry;
1422                         }
1423                         error = -1;
1424                         goto cleanup;
1425                 }
1426         } else {
1427                 free = inode->i_sb->s_blocksize;
1428         }
1429
1430         while (new_extra_isize > 0) {
1431                 size_t offs, size, entry_size;
1432                 struct ext4_xattr_entry *small_entry = NULL;
1433                 struct ext4_xattr_info i = {
1434                         .value = NULL,
1435                         .value_len = 0,
1436                 };
1437                 unsigned int total_size;  /* EA entry size + value size */
1438                 unsigned int shift_bytes; /* No. of bytes to shift EAs by? */
1439                 unsigned int min_total_size = ~0U;
1440
1441                 is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
1442                 bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
1443                 if (!is || !bs) {
1444                         error = -ENOMEM;
1445                         goto cleanup;
1446                 }
1447
1448                 is->s.not_found = -ENODATA;
1449                 bs->s.not_found = -ENODATA;
1450                 is->iloc.bh = NULL;
1451                 bs->bh = NULL;
1452
1453                 last = IFIRST(header);
1454                 /* Find the entry best suited to be pushed into EA block */
1455                 entry = NULL;
1456                 for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1457                         total_size =
1458                         EXT4_XATTR_SIZE(le32_to_cpu(last->e_value_size)) +
1459                                         EXT4_XATTR_LEN(last->e_name_len);
1460                         if (total_size <= free && total_size < min_total_size) {
1461                                 if (total_size < new_extra_isize) {
1462                                         small_entry = last;
1463                                 } else {
1464                                         entry = last;
1465                                         min_total_size = total_size;
1466                                 }
1467                         }
1468                 }
1469
1470                 if (entry == NULL) {
1471                         if (small_entry) {
1472                                 entry = small_entry;
1473                         } else {
1474                                 if (!tried_min_extra_isize &&
1475                                     s_min_extra_isize) {
1476                                         tried_min_extra_isize++;
1477                                         new_extra_isize = s_min_extra_isize;
1478                                         kfree(is); is = NULL;
1479                                         kfree(bs); bs = NULL;
1480                                         brelse(bh);
1481                                         goto retry;
1482                                 }
1483                                 error = -1;
1484                                 goto cleanup;
1485                         }
1486                 }
1487                 offs = le16_to_cpu(entry->e_value_offs);
1488                 size = le32_to_cpu(entry->e_value_size);
1489                 entry_size = EXT4_XATTR_LEN(entry->e_name_len);
1490                 i.name_index = entry->e_name_index,
1491                 buffer = kmalloc(EXT4_XATTR_SIZE(size), GFP_NOFS);
1492                 b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
1493                 if (!buffer || !b_entry_name) {
1494                         error = -ENOMEM;
1495                         goto cleanup;
1496                 }
1497                 /* Save the entry name and the entry value */
1498                 memcpy(buffer, (void *)IFIRST(header) + offs,
1499                        EXT4_XATTR_SIZE(size));
1500                 memcpy(b_entry_name, entry->e_name, entry->e_name_len);
1501                 b_entry_name[entry->e_name_len] = '\0';
1502                 i.name = b_entry_name;
1503
1504                 error = ext4_get_inode_loc(inode, &is->iloc);
1505                 if (error)
1506                         goto cleanup;
1507
1508                 error = ext4_xattr_ibody_find(inode, &i, is);
1509                 if (error)
1510                         goto cleanup;
1511
1512                 /* Remove the chosen entry from the inode */
1513                 error = ext4_xattr_ibody_set(handle, inode, &i, is);
1514                 if (error)
1515                         goto cleanup;
1516
1517                 entry = IFIRST(header);
1518                 if (entry_size + EXT4_XATTR_SIZE(size) >= new_extra_isize)
1519                         shift_bytes = new_extra_isize;
1520                 else
1521                         shift_bytes = entry_size + size;
1522                 /* Adjust the offsets and shift the remaining entries ahead */
1523                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize -
1524                         shift_bytes, (void *)raw_inode +
1525                         EXT4_GOOD_OLD_INODE_SIZE + extra_isize + shift_bytes,
1526                         (void *)header, total_ino - entry_size,
1527                         inode->i_sb->s_blocksize);
1528
1529                 extra_isize += shift_bytes;
1530                 new_extra_isize -= shift_bytes;
1531                 EXT4_I(inode)->i_extra_isize = extra_isize;
1532
1533                 i.name = b_entry_name;
1534                 i.value = buffer;
1535                 i.value_len = size;
1536                 error = ext4_xattr_block_find(inode, &i, bs);
1537                 if (error)
1538                         goto cleanup;
1539
1540                 /* Add entry which was removed from the inode into the block */
1541                 error = ext4_xattr_block_set(handle, inode, &i, bs);
1542                 if (error)
1543                         goto cleanup;
1544                 kfree(b_entry_name);
1545                 kfree(buffer);
1546                 b_entry_name = NULL;
1547                 buffer = NULL;
1548                 brelse(is->iloc.bh);
1549                 kfree(is);
1550                 kfree(bs);
1551         }
1552         brelse(bh);
1553         up_write(&EXT4_I(inode)->xattr_sem);
1554         return 0;
1555
1556 cleanup:
1557         kfree(b_entry_name);
1558         kfree(buffer);
1559         if (is)
1560                 brelse(is->iloc.bh);
1561         kfree(is);
1562         kfree(bs);
1563         brelse(bh);
1564         up_write(&EXT4_I(inode)->xattr_sem);
1565         return error;
1566 }
1567
1568
1569
1570 /*
1571  * ext4_xattr_delete_inode()
1572  *
1573  * Free extended attribute resources associated with this inode. This
1574  * is called immediately before an inode is freed. We have exclusive
1575  * access to the inode.
1576  */
1577 void
1578 ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)
1579 {
1580         struct buffer_head *bh = NULL;
1581
1582         if (!EXT4_I(inode)->i_file_acl)
1583                 goto cleanup;
1584         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1585         if (!bh) {
1586                 EXT4_ERROR_INODE(inode, "block %llu read error",
1587                                  EXT4_I(inode)->i_file_acl);
1588                 goto cleanup;
1589         }
1590         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
1591             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1592                 EXT4_ERROR_INODE(inode, "bad block %llu",
1593                                  EXT4_I(inode)->i_file_acl);
1594                 goto cleanup;
1595         }
1596         ext4_xattr_release_block(handle, inode, bh);
1597         EXT4_I(inode)->i_file_acl = 0;
1598
1599 cleanup:
1600         brelse(bh);
1601 }
1602
1603 /*
1604  * ext4_xattr_cache_insert()
1605  *
1606  * Create a new entry in the extended attribute cache, and insert
1607  * it unless such an entry is already in the cache.
1608  *
1609  * Returns 0, or a negative error number on failure.
1610  */
1611 static void
1612 ext4_xattr_cache_insert(struct mb_cache *ext4_mb_cache, struct buffer_head *bh)
1613 {
1614         struct ext4_xattr_header *header = BHDR(bh);
1615         __u32 hash = le32_to_cpu(header->h_hash);
1616         int reusable = le32_to_cpu(header->h_refcount) <
1617                        EXT4_XATTR_REFCOUNT_MAX;
1618         int error;
1619
1620         error = mb_cache_entry_create(ext4_mb_cache, GFP_NOFS, hash,
1621                                       bh->b_blocknr, reusable);
1622         if (error) {
1623                 if (error == -EBUSY)
1624                         ea_bdebug(bh, "already in cache");
1625         } else
1626                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1627 }
1628
1629 /*
1630  * ext4_xattr_cmp()
1631  *
1632  * Compare two extended attribute blocks for equality.
1633  *
1634  * Returns 0 if the blocks are equal, 1 if they differ, and
1635  * a negative error number on errors.
1636  */
1637 static int
1638 ext4_xattr_cmp(struct ext4_xattr_header *header1,
1639                struct ext4_xattr_header *header2)
1640 {
1641         struct ext4_xattr_entry *entry1, *entry2;
1642
1643         entry1 = ENTRY(header1+1);
1644         entry2 = ENTRY(header2+1);
1645         while (!IS_LAST_ENTRY(entry1)) {
1646                 if (IS_LAST_ENTRY(entry2))
1647                         return 1;
1648                 if (entry1->e_hash != entry2->e_hash ||
1649                     entry1->e_name_index != entry2->e_name_index ||
1650                     entry1->e_name_len != entry2->e_name_len ||
1651                     entry1->e_value_size != entry2->e_value_size ||
1652                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1653                         return 1;
1654                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1655                         return -EFSCORRUPTED;
1656                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1657                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1658                            le32_to_cpu(entry1->e_value_size)))
1659                         return 1;
1660
1661                 entry1 = EXT4_XATTR_NEXT(entry1);
1662                 entry2 = EXT4_XATTR_NEXT(entry2);
1663         }
1664         if (!IS_LAST_ENTRY(entry2))
1665                 return 1;
1666         return 0;
1667 }
1668
1669 /*
1670  * ext4_xattr_cache_find()
1671  *
1672  * Find an identical extended attribute block.
1673  *
1674  * Returns a pointer to the block found, or NULL if such a block was
1675  * not found or an error occurred.
1676  */
1677 static struct buffer_head *
1678 ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
1679                       struct mb_cache_entry **pce)
1680 {
1681         __u32 hash = le32_to_cpu(header->h_hash);
1682         struct mb_cache_entry *ce;
1683         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
1684
1685         if (!header->h_hash)
1686                 return NULL;  /* never share */
1687         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1688         ce = mb_cache_entry_find_first(ext4_mb_cache, hash);
1689         while (ce) {
1690                 struct buffer_head *bh;
1691
1692                 bh = sb_bread(inode->i_sb, ce->e_block);
1693                 if (!bh) {
1694                         EXT4_ERROR_INODE(inode, "block %lu read error",
1695                                          (unsigned long) ce->e_block);
1696                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
1697                         *pce = ce;
1698                         return bh;
1699                 }
1700                 brelse(bh);
1701                 ce = mb_cache_entry_find_next(ext4_mb_cache, ce);
1702         }
1703         return NULL;
1704 }
1705
1706 #define NAME_HASH_SHIFT 5
1707 #define VALUE_HASH_SHIFT 16
1708
1709 /*
1710  * ext4_xattr_hash_entry()
1711  *
1712  * Compute the hash of an extended attribute.
1713  */
1714 static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
1715                                          struct ext4_xattr_entry *entry)
1716 {
1717         __u32 hash = 0;
1718         char *name = entry->e_name;
1719         int n;
1720
1721         for (n = 0; n < entry->e_name_len; n++) {
1722                 hash = (hash << NAME_HASH_SHIFT) ^
1723                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1724                        *name++;
1725         }
1726
1727         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1728                 __le32 *value = (__le32 *)((char *)header +
1729                         le16_to_cpu(entry->e_value_offs));
1730                 for (n = (le32_to_cpu(entry->e_value_size) +
1731                      EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {
1732                         hash = (hash << VALUE_HASH_SHIFT) ^
1733                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1734                                le32_to_cpu(*value++);
1735                 }
1736         }
1737         entry->e_hash = cpu_to_le32(hash);
1738 }
1739
1740 #undef NAME_HASH_SHIFT
1741 #undef VALUE_HASH_SHIFT
1742
1743 #define BLOCK_HASH_SHIFT 16
1744
1745 /*
1746  * ext4_xattr_rehash()
1747  *
1748  * Re-compute the extended attribute hash value after an entry has changed.
1749  */
1750 static void ext4_xattr_rehash(struct ext4_xattr_header *header,
1751                               struct ext4_xattr_entry *entry)
1752 {
1753         struct ext4_xattr_entry *here;
1754         __u32 hash = 0;
1755
1756         ext4_xattr_hash_entry(header, entry);
1757         here = ENTRY(header+1);
1758         while (!IS_LAST_ENTRY(here)) {
1759                 if (!here->e_hash) {
1760                         /* Block is not shared if an entry's hash value == 0 */
1761                         hash = 0;
1762                         break;
1763                 }
1764                 hash = (hash << BLOCK_HASH_SHIFT) ^
1765                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1766                        le32_to_cpu(here->e_hash);
1767                 here = EXT4_XATTR_NEXT(here);
1768         }
1769         header->h_hash = cpu_to_le32(hash);
1770 }
1771
1772 #undef BLOCK_HASH_SHIFT
1773
1774 #define HASH_BUCKET_BITS        10
1775
1776 struct mb_cache *
1777 ext4_xattr_create_cache(void)
1778 {
1779         return mb_cache_create(HASH_BUCKET_BITS);
1780 }
1781
1782 void ext4_xattr_destroy_cache(struct mb_cache *cache)
1783 {
1784         if (cache)
1785                 mb_cache_destroy(cache);
1786 }
1787