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, fmt, ...)                                     \
  65         printk(KERN_DEBUG "inode %s:%lu: " fmt "\n",                    \
  66                inode->i_sb->s_id, inode->i_ino, ##__VA_ARGS__)
  67 # define ea_bdebug(bh, fmt, ...)                                        \
  68         printk(KERN_DEBUG "block %pg:%lu: " fmt "\n",                   \
  69                bh->b_bdev, (unsigned long)bh->b_blocknr, ##__VA_ARGS__)
  70 #else
  71 # define ea_idebug(inode, fmt, ...)     no_printk(fmt, ##__VA_ARGS__)
  72 # define ea_bdebug(bh, fmt, ...)        no_printk(fmt, ##__VA_ARGS__)
  73 #endif
  74
  75 static void ext4_xattr_cache_insert(struct mb_cache *, struct buffer_head *);
  76 static struct buffer_head *ext4_xattr_cache_find(struct inode *,
  77                                                  struct ext4_xattr_header *,
  78                                                  struct mb_cache_entry **);
  79 static void ext4_xattr_rehash(struct ext4_xattr_header *,
  80                               struct ext4_xattr_entry *);
  81 static int ext4_xattr_list(struct dentry *dentry, char *buffer,
  82                            size_t buffer_size);
  83
  84 static const struct xattr_handler *ext4_xattr_handler_map[] = {
  85         [EXT4_XATTR_INDEX_USER]              = &ext4_xattr_user_handler,
  86 #ifdef CONFIG_EXT4_FS_POSIX_ACL
  87         [EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &posix_acl_access_xattr_handler,
  88         [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
  89 #endif
  90         [EXT4_XATTR_INDEX_TRUSTED]           = &ext4_xattr_trusted_handler,
  91 #ifdef CONFIG_EXT4_FS_SECURITY
  92         [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
  93 #endif
  94 };
  95
  96 const struct xattr_handler *ext4_xattr_handlers[] = {
  97         &ext4_xattr_user_handler,
  98         &ext4_xattr_trusted_handler,
  99 #ifdef CONFIG_EXT4_FS_POSIX_ACL
 100         &posix_acl_access_xattr_handler,
 101         &posix_acl_default_xattr_handler,
 102 #endif
 103 #ifdef CONFIG_EXT4_FS_SECURITY
 104         &ext4_xattr_security_handler,
 105 #endif
 106         NULL
 107 };
 108
 109 #define EXT4_GET_MB_CACHE(inode)        (((struct ext4_sb_info *) \
 110                                 inode->i_sb->s_fs_info)->s_mb_cache)
 111
 112 static __le32 ext4_xattr_block_csum(struct inode *inode,
 113                                     sector_t block_nr,
 114                                     struct ext4_xattr_header *hdr)
 115 {
 116         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 117         __u32 csum;
 118         __le64 dsk_block_nr = cpu_to_le64(block_nr);
 119         __u32 dummy_csum = 0;
 120         int offset = offsetof(struct ext4_xattr_header, h_checksum);
 121
 122         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&dsk_block_nr,
 123                            sizeof(dsk_block_nr));
 124         csum = ext4_chksum(sbi, csum, (__u8 *)hdr, offset);
 125         csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, sizeof(dummy_csum));
 126         offset += sizeof(dummy_csum);
 127         csum = ext4_chksum(sbi, csum, (__u8 *)hdr + offset,
 128                            EXT4_BLOCK_SIZE(inode->i_sb) - offset);
 129
 130         return cpu_to_le32(csum);
 131 }
 132
 133 static int ext4_xattr_block_csum_verify(struct inode *inode,
 134                                         sector_t block_nr,
 135                                         struct ext4_xattr_header *hdr)
 136 {
 137         if (ext4_has_metadata_csum(inode->i_sb) &&
 138             (hdr->h_checksum != ext4_xattr_block_csum(inode, block_nr, hdr)))
 139                 return 0;
 140         return 1;
 141 }
 142
 143 static void ext4_xattr_block_csum_set(struct inode *inode,
 144                                       sector_t block_nr,
 145                                       struct ext4_xattr_header *hdr)
 146 {
 147         if (!ext4_has_metadata_csum(inode->i_sb))
 148                 return;
 149
 150         hdr->h_checksum = ext4_xattr_block_csum(inode, block_nr, hdr);
 151 }
 152
 153 static inline int ext4_handle_dirty_xattr_block(handle_t *handle,
 154                                                 struct inode *inode,
 155                                                 struct buffer_head *bh)
 156 {
 157         ext4_xattr_block_csum_set(inode, bh->b_blocknr, BHDR(bh));
 158         return ext4_handle_dirty_metadata(handle, inode, bh);
 159 }
 160
 161 static inline const struct xattr_handler *
 162 ext4_xattr_handler(int name_index)
 163 {
 164         const struct xattr_handler *handler = NULL;
 165
 166         if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
 167                 handler = ext4_xattr_handler_map[name_index];
 168         return handler;
 169 }
 170
 171 /*
 172  * Inode operation listxattr()
 173  *
 174  * d_inode(dentry)->i_mutex: don't care
 175  */
 176 ssize_t
 177 ext4_listxattr(struct dentry *dentry, char *buffer, size_t size)
 178 {
 179         return ext4_xattr_list(dentry, buffer, size);
 180 }
 181
 182 static int
 183 ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end,
 184                        void *value_start)
 185 {
 186         struct ext4_xattr_entry *e = entry;
 187
 188         /* Find the end of the names list */
 189         while (!IS_LAST_ENTRY(e)) {
 190                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(e);
 191                 if ((void *)next >= end)
 192                         return -EFSCORRUPTED;
 193                 e = next;
 194         }
 195
 196         /* Check the values */
 197         while (!IS_LAST_ENTRY(entry)) {
 198                 if (entry->e_value_block != 0)
 199                         return -EFSCORRUPTED;
 200                 if (entry->e_value_size != 0) {
 201                         u16 offs = le16_to_cpu(entry->e_value_offs);
 202                         u32 size = le32_to_cpu(entry->e_value_size);
 203                         void *value;
 204
 205                         /*
 206                          * The value cannot overlap the names, and the value
 207                          * with padding cannot extend beyond 'end'.  Check both
 208                          * the padded and unpadded sizes, since the size may
 209                          * overflow to 0 when adding padding.
 210                          */
 211                         if (offs > end - value_start)
 212                                 return -EFSCORRUPTED;
 213                         value = value_start + offs;
 214                         if (value < (void *)e + sizeof(u32) ||
 215                             size > end - value ||
 216                             EXT4_XATTR_SIZE(size) > end - value)
 217                                 return -EFSCORRUPTED;
 218                 }
 219                 entry = EXT4_XATTR_NEXT(entry);
 220         }
 221
 222         return 0;
 223 }
 224
 225 static inline int
 226 ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh)
 227 {
 228         int error;
 229
 230         if (buffer_verified(bh))
 231                 return 0;
 232
 233         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
 234             BHDR(bh)->h_blocks != cpu_to_le32(1))
 235                 return -EFSCORRUPTED;
 236         if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh)))
 237                 return -EFSBADCRC;
 238         error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size,
 239                                        bh->b_data);
 240         if (!error)
 241                 set_buffer_verified(bh);
 242         return error;
 243 }
 244
 245 static int
 246 __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
 247                          void *end, const char *function, unsigned int line)
 248 {
 249         int error = -EFSCORRUPTED;
 250
 251         if (end - (void *)header < sizeof(*header) + sizeof(u32) ||
 252             (header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)))
 253                 goto errout;
 254         error = ext4_xattr_check_names(IFIRST(header), end, IFIRST(header));
 255 errout:
 256         if (error)
 257                 __ext4_error_inode(inode, function, line, 0,
 258                                    "corrupted in-inode xattr");
 259         return error;
 260 }
 261
 262 #define xattr_check_inode(inode, header, end) \
 263         __xattr_check_inode((inode), (header), (end), __func__, __LINE__)
 264
 265 static inline int
 266 ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size)
 267 {
 268         size_t value_size = le32_to_cpu(entry->e_value_size);
 269
 270         if (entry->e_value_block != 0 || value_size > size ||
 271             le16_to_cpu(entry->e_value_offs) + value_size > size)
 272                 return -EFSCORRUPTED;
 273         return 0;
 274 }
 275
 276 static int
 277 ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
 278                       const char *name, size_t size, int sorted)
 279 {
 280         struct ext4_xattr_entry *entry;
 281         size_t name_len;
 282         int cmp = 1;
 283
 284         if (name == NULL)
 285                 return -EINVAL;
 286         name_len = strlen(name);
 287         entry = *pentry;
 288         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 289                 cmp = name_index - entry->e_name_index;
 290                 if (!cmp)
 291                         cmp = name_len - entry->e_name_len;
 292                 if (!cmp)
 293                         cmp = memcmp(name, entry->e_name, name_len);
 294                 if (cmp <= 0 && (sorted || cmp == 0))
 295                         break;
 296         }
 297         *pentry = entry;
 298         if (!cmp && ext4_xattr_check_entry(entry, size))
 299                 return -EFSCORRUPTED;
 300         return cmp ? -ENODATA : 0;
 301 }
 302
 303 static int
 304 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
 305                      void *buffer, size_t buffer_size)
 306 {
 307         struct buffer_head *bh = NULL;
 308         struct ext4_xattr_entry *entry;
 309         size_t size;
 310         int error;
 311         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 312
 313         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 314                   name_index, name, buffer, (long)buffer_size);
 315
 316         error = -ENODATA;
 317         if (!EXT4_I(inode)->i_file_acl)
 318                 goto cleanup;
 319         ea_idebug(inode, "reading block %llu",
 320                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 321         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 322         if (!bh)
 323                 goto cleanup;
 324         ea_bdebug(bh, "b_count=%d, refcount=%d",
 325                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 326         if (ext4_xattr_check_block(inode, bh)) {
 327 bad_block:
 328                 EXT4_ERROR_INODE(inode, "bad block %llu",
 329                                  EXT4_I(inode)->i_file_acl);
 330                 error = -EFSCORRUPTED;
 331                 goto cleanup;
 332         }
 333         ext4_xattr_cache_insert(ext4_mb_cache, bh);
 334         entry = BFIRST(bh);
 335         error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
 336         if (error == -EFSCORRUPTED)
 337                 goto bad_block;
 338         if (error)
 339                 goto cleanup;
 340         size = le32_to_cpu(entry->e_value_size);
 341         if (buffer) {
 342                 error = -ERANGE;
 343                 if (size > buffer_size)
 344                         goto cleanup;
 345                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
 346                        size);
 347         }
 348         error = size;
 349
 350 cleanup:
 351         brelse(bh);
 352         return error;
 353 }
 354
 355 int
 356 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 357                      void *buffer, size_t buffer_size)
 358 {
 359         struct ext4_xattr_ibody_header *header;
 360         struct ext4_xattr_entry *entry;
 361         struct ext4_inode *raw_inode;
 362         struct ext4_iloc iloc;
 363         size_t size;
 364         void *end;
 365         int error;
 366
 367         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 368                 return -ENODATA;
 369         error = ext4_get_inode_loc(inode, &iloc);
 370         if (error)
 371                 return error;
 372         raw_inode = ext4_raw_inode(&iloc);
 373         header = IHDR(inode, raw_inode);
 374         entry = IFIRST(header);
 375         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 376         error = xattr_check_inode(inode, header, end);
 377         if (error)
 378                 goto cleanup;
 379         error = ext4_xattr_find_entry(&entry, name_index, name,
 380                                       end - (void *)entry, 0);
 381         if (error)
 382                 goto cleanup;
 383         size = le32_to_cpu(entry->e_value_size);
 384         if (buffer) {
 385                 error = -ERANGE;
 386                 if (size > buffer_size)
 387                         goto cleanup;
 388                 memcpy(buffer, (void *)IFIRST(header) +
 389                        le16_to_cpu(entry->e_value_offs), size);
 390         }
 391         error = size;
 392
 393 cleanup:
 394         brelse(iloc.bh);
 395         return error;
 396 }
 397
 398 /*
 399  * ext4_xattr_get()
 400  *
 401  * Copy an extended attribute into the buffer
 402  * provided, or compute the buffer size required.
 403  * Buffer is NULL to compute the size of the buffer required.
 404  *
 405  * Returns a negative error number on failure, or the number of bytes
 406  * used / required on success.
 407  */
 408 int
 409 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
 410                void *buffer, size_t buffer_size)
 411 {
 412         int error;
 413
 414         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 415                 return -EIO;
 416
 417         if (strlen(name) > 255)
 418                 return -ERANGE;
 419
 420         down_read(&EXT4_I(inode)->xattr_sem);
 421         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
 422                                      buffer_size);
 423         if (error == -ENODATA)
 424                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
 425                                              buffer_size);
 426         up_read(&EXT4_I(inode)->xattr_sem);
 427         return error;
 428 }
 429
 430 static int
 431 ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,
 432                         char *buffer, size_t buffer_size)
 433 {
 434         size_t rest = buffer_size;
 435
 436         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 437                 const struct xattr_handler *handler =
 438                         ext4_xattr_handler(entry->e_name_index);
 439
 440                 if (handler && (!handler->list || handler->list(dentry))) {
 441                         const char *prefix = handler->prefix ?: handler->name;
 442                         size_t prefix_len = strlen(prefix);
 443                         size_t size = prefix_len + entry->e_name_len + 1;
 444
 445                         if (buffer) {
 446                                 if (size > rest)
 447                                         return -ERANGE;
 448                                 memcpy(buffer, prefix, prefix_len);
 449                                 buffer += prefix_len;
 450                                 memcpy(buffer, entry->e_name, entry->e_name_len);
 451                                 buffer += entry->e_name_len;
 452                                 *buffer++ = 0;
 453                         }
 454                         rest -= size;
 455                 }
 456         }
 457         return buffer_size - rest;  /* total size */
 458 }
 459
 460 static int
 461 ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 462 {
 463         struct inode *inode = d_inode(dentry);
 464         struct buffer_head *bh = NULL;
 465         int error;
 466         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 467
 468         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 469                   buffer, (long)buffer_size);
 470
 471         error = 0;
 472         if (!EXT4_I(inode)->i_file_acl)
 473                 goto cleanup;
 474         ea_idebug(inode, "reading block %llu",
 475                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 476         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 477         error = -EIO;
 478         if (!bh)
 479                 goto cleanup;
 480         ea_bdebug(bh, "b_count=%d, refcount=%d",
 481                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 482         if (ext4_xattr_check_block(inode, bh)) {
 483                 EXT4_ERROR_INODE(inode, "bad block %llu",
 484                                  EXT4_I(inode)->i_file_acl);
 485                 error = -EFSCORRUPTED;
 486                 goto cleanup;
 487         }
 488         ext4_xattr_cache_insert(ext4_mb_cache, bh);
 489         error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
 490
 491 cleanup:
 492         brelse(bh);
 493
 494         return error;
 495 }
 496
 497 static int
 498 ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 499 {
 500         struct inode *inode = d_inode(dentry);
 501         struct ext4_xattr_ibody_header *header;
 502         struct ext4_inode *raw_inode;
 503         struct ext4_iloc iloc;
 504         void *end;
 505         int error;
 506
 507         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 508                 return 0;
 509         error = ext4_get_inode_loc(inode, &iloc);
 510         if (error)
 511                 return error;
 512         raw_inode = ext4_raw_inode(&iloc);
 513         header = IHDR(inode, raw_inode);
 514         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 515         error = xattr_check_inode(inode, header, end);
 516         if (error)
 517                 goto cleanup;
 518         error = ext4_xattr_list_entries(dentry, IFIRST(header),
 519                                         buffer, buffer_size);
 520
 521 cleanup:
 522         brelse(iloc.bh);
 523         return error;
 524 }
 525
 526 /*
 527  * ext4_xattr_list()
 528  *
 529  * Copy a list of attribute names into the buffer
 530  * provided, or compute the buffer size required.
 531  * Buffer is NULL to compute the size of the buffer required.
 532  *
 533  * Returns a negative error number on failure, or the number of bytes
 534  * used / required on success.
 535  */
 536 static int
 537 ext4_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 538 {
 539         int ret, ret2;
 540
 541         down_read(&EXT4_I(d_inode(dentry))->xattr_sem);
 542         ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size);
 543         if (ret < 0)
 544                 goto errout;
 545         if (buffer) {
 546                 buffer += ret;
 547                 buffer_size -= ret;
 548         }
 549         ret = ext4_xattr_block_list(dentry, buffer, buffer_size);
 550         if (ret < 0)
 551                 goto errout;
 552         ret += ret2;
 553 errout:
 554         up_read(&EXT4_I(d_inode(dentry))->xattr_sem);
 555         return ret;
 556 }
 557
 558 /*
 559  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 560  * not set, set it.
 561  */
 562 static void ext4_xattr_update_super_block(handle_t *handle,
 563                                           struct super_block *sb)
 564 {
 565         if (ext4_has_feature_xattr(sb))
 566                 return;
 567
 568         BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
 569         if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
 570                 ext4_set_feature_xattr(sb);
 571                 ext4_handle_dirty_super(handle, sb);
 572         }
 573 }
 574
 575 /*
 576  * Release the xattr block BH: If the reference count is > 1, decrement it;
 577  * otherwise free the block.
 578  */
 579 static void
 580 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
 581                          struct buffer_head *bh)
 582 {
 583         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 584         u32 hash, ref;
 585         int error = 0;
 586
 587         BUFFER_TRACE(bh, "get_write_access");
 588         error = ext4_journal_get_write_access(handle, bh);
 589         if (error)
 590                 goto out;
 591
 592         lock_buffer(bh);
 593         hash = le32_to_cpu(BHDR(bh)->h_hash);
 594         ref = le32_to_cpu(BHDR(bh)->h_refcount);
 595         if (ref == 1) {
 596                 ea_bdebug(bh, "refcount now=0; freeing");
 597                 /*
 598                  * This must happen under buffer lock for
 599                  * ext4_xattr_block_set() to reliably detect freed block
 600                  */
 601                 mb_cache_entry_delete_block(ext4_mb_cache, hash, bh->b_blocknr);
 602                 get_bh(bh);
 603                 unlock_buffer(bh);
 604                 ext4_free_blocks(handle, inode, bh, 0, 1,
 605                                  EXT4_FREE_BLOCKS_METADATA |
 606                                  EXT4_FREE_BLOCKS_FORGET);
 607         } else {
 608                 ref--;
 609                 BHDR(bh)->h_refcount = cpu_to_le32(ref);
 610                 if (ref == EXT4_XATTR_REFCOUNT_MAX - 1) {
 611                         struct mb_cache_entry *ce;
 612
 613                         ce = mb_cache_entry_get(ext4_mb_cache, hash,
 614                                                 bh->b_blocknr);
 615                         if (ce) {
 616                                 ce->e_reusable = 1;
 617                                 mb_cache_entry_put(ext4_mb_cache, ce);
 618                         }
 619                 }
 620
 621                 /*
 622                  * Beware of this ugliness: Releasing of xattr block references
 623                  * from different inodes can race and so we have to protect
 624                  * from a race where someone else frees the block (and releases
 625                  * its journal_head) before we are done dirtying the buffer. In
 626                  * nojournal mode this race is harmless and we actually cannot
 627                  * call ext4_handle_dirty_xattr_block() with locked buffer as
 628                  * that function can call sync_dirty_buffer() so for that case
 629                  * we handle the dirtying after unlocking the buffer.
 630                  */
 631                 if (ext4_handle_valid(handle))
 632                         error = ext4_handle_dirty_xattr_block(handle, inode,
 633                                                               bh);
 634                 unlock_buffer(bh);
 635                 if (!ext4_handle_valid(handle))
 636                         error = ext4_handle_dirty_xattr_block(handle, inode,
 637                                                               bh);
 638                 if (IS_SYNC(inode))
 639                         ext4_handle_sync(handle);
 640                 dquot_free_block(inode, EXT4_C2B(EXT4_SB(inode->i_sb), 1));
 641                 ea_bdebug(bh, "refcount now=%d; releasing",
 642                           le32_to_cpu(BHDR(bh)->h_refcount));
 643         }
 644 out:
 645         ext4_std_error(inode->i_sb, error);
 646         return;
 647 }
 648
 649 /*
 650  * Find the available free space for EAs. This also returns the total number of
 651  * bytes used by EA entries.
 652  */
 653 static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
 654                                     size_t *min_offs, void *base, int *total)
 655 {
 656         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 657                 if (last->e_value_size) {
 658                         size_t offs = le16_to_cpu(last->e_value_offs);
 659                         if (offs < *min_offs)
 660                                 *min_offs = offs;
 661                 }
 662                 if (total)
 663                         *total += EXT4_XATTR_LEN(last->e_name_len);
 664         }
 665         return (*min_offs - ((void *)last - base) - sizeof(__u32));
 666 }
 667
 668 static int
 669 ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
 670 {
 671         struct ext4_xattr_entry *last;
 672         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
 673
 674         /* Compute min_offs and last. */
 675         last = s->first;
 676         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 677                 if (last->e_value_size) {
 678                         size_t offs = le16_to_cpu(last->e_value_offs);
 679                         if (offs < min_offs)
 680                                 min_offs = offs;
 681                 }
 682         }
 683         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
 684         if (!s->not_found) {
 685                 if (s->here->e_value_size) {
 686                         size_t size = le32_to_cpu(s->here->e_value_size);
 687                         free += EXT4_XATTR_SIZE(size);
 688                 }
 689                 free += EXT4_XATTR_LEN(name_len);
 690         }
 691         if (i->value) {
 692                 if (free < EXT4_XATTR_LEN(name_len) +
 693                            EXT4_XATTR_SIZE(i->value_len))
 694                         return -ENOSPC;
 695         }
 696
 697         if (i->value && s->not_found) {
 698                 /* Insert the new name. */
 699                 size_t size = EXT4_XATTR_LEN(name_len);
 700                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
 701                 memmove((void *)s->here + size, s->here, rest);
 702                 memset(s->here, 0, size);
 703                 s->here->e_name_index = i->name_index;
 704                 s->here->e_name_len = name_len;
 705                 memcpy(s->here->e_name, i->name, name_len);
 706         } else {
 707                 if (s->here->e_value_size) {
 708                         void *first_val = s->base + min_offs;
 709                         size_t offs = le16_to_cpu(s->here->e_value_offs);
 710                         void *val = s->base + offs;
 711                         size_t size = EXT4_XATTR_SIZE(
 712                                 le32_to_cpu(s->here->e_value_size));
 713
 714                         if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
 715                                 /* The old and the new value have the same
 716                                    size. Just replace. */
 717                                 s->here->e_value_size =
 718                                         cpu_to_le32(i->value_len);
 719                                 if (i->value == EXT4_ZERO_XATTR_VALUE) {
 720                                         memset(val, 0, size);
 721                                 } else {
 722                                         /* Clear pad bytes first. */
 723                                         memset(val + size - EXT4_XATTR_PAD, 0,
 724                                                EXT4_XATTR_PAD);
 725                                         memcpy(val, i->value, i->value_len);
 726                                 }
 727                                 return 0;
 728                         }
 729
 730                         /* Remove the old value. */
 731                         memmove(first_val + size, first_val, val - first_val);
 732                         memset(first_val, 0, size);
 733                         s->here->e_value_size = 0;
 734                         s->here->e_value_offs = 0;
 735                         min_offs += size;
 736
 737                         /* Adjust all value offsets. */
 738                         last = s->first;
 739                         while (!IS_LAST_ENTRY(last)) {
 740                                 size_t o = le16_to_cpu(last->e_value_offs);
 741                                 if (last->e_value_size && o < offs)
 742                                         last->e_value_offs =
 743                                                 cpu_to_le16(o + size);
 744                                 last = EXT4_XATTR_NEXT(last);
 745                         }
 746                 }
 747                 if (!i->value) {
 748                         /* Remove the old name. */
 749                         size_t size = EXT4_XATTR_LEN(name_len);
 750                         last = ENTRY((void *)last - size);
 751                         memmove(s->here, (void *)s->here + size,
 752                                 (void *)last - (void *)s->here + sizeof(__u32));
 753                         memset(last, 0, size);
 754                 }
 755         }
 756
 757         if (i->value) {
 758                 /* Insert the new value. */
 759                 s->here->e_value_size = cpu_to_le32(i->value_len);
 760                 if (i->value_len) {
 761                         size_t size = EXT4_XATTR_SIZE(i->value_len);
 762                         void *val = s->base + min_offs - size;
 763                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
 764                         if (i->value == EXT4_ZERO_XATTR_VALUE) {
 765                                 memset(val, 0, size);
 766                         } else {
 767                                 /* Clear the pad bytes first. */
 768                                 memset(val + size - EXT4_XATTR_PAD, 0,
 769                                        EXT4_XATTR_PAD);
 770                                 memcpy(val, i->value, i->value_len);
 771                         }
 772                 }
 773         }
 774         return 0;
 775 }
 776
 777 struct ext4_xattr_block_find {
 778         struct ext4_xattr_search s;
 779         struct buffer_head *bh;
 780 };
 781
 782 static int
 783 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
 784                       struct ext4_xattr_block_find *bs)
 785 {
 786         struct super_block *sb = inode->i_sb;
 787         int error;
 788
 789         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
 790                   i->name_index, i->name, i->value, (long)i->value_len);
 791
 792         if (EXT4_I(inode)->i_file_acl) {
 793                 /* The inode already has an extended attribute block. */
 794                 bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);
 795                 error = -EIO;
 796                 if (!bs->bh)
 797                         goto cleanup;
 798                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
 799                         atomic_read(&(bs->bh->b_count)),
 800                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
 801                 if (ext4_xattr_check_block(inode, bs->bh)) {
 802                         EXT4_ERROR_INODE(inode, "bad block %llu",
 803                                          EXT4_I(inode)->i_file_acl);
 804                         error = -EFSCORRUPTED;
 805                         goto cleanup;
 806                 }
 807                 /* Find the named attribute. */
 808                 bs->s.base = BHDR(bs->bh);
 809                 bs->s.first = BFIRST(bs->bh);
 810                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
 811                 bs->s.here = bs->s.first;
 812                 error = ext4_xattr_find_entry(&bs->s.here, i->name_index,
 813                                               i->name, bs->bh->b_size, 1);
 814                 if (error && error != -ENODATA)
 815                         goto cleanup;
 816                 bs->s.not_found = error;
 817         }
 818         error = 0;
 819
 820 cleanup:
 821         return error;
 822 }
 823
 824 static int
 825 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
 826                      struct ext4_xattr_info *i,
 827                      struct ext4_xattr_block_find *bs)
 828 {
 829         struct super_block *sb = inode->i_sb;
 830         struct buffer_head *new_bh = NULL;
 831         struct ext4_xattr_search *s = &bs->s;
 832         struct mb_cache_entry *ce = NULL;
 833         int error = 0;
 834         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
 835
 836 #define header(x) ((struct ext4_xattr_header *)(x))
 837
 838         if (i->value && i->value_len > sb->s_blocksize)
 839                 return -ENOSPC;
 840         if (s->base) {
 841                 BUFFER_TRACE(bs->bh, "get_write_access");
 842                 error = ext4_journal_get_write_access(handle, bs->bh);
 843                 if (error)
 844                         goto cleanup;
 845                 lock_buffer(bs->bh);
 846
 847                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 848                         __u32 hash = le32_to_cpu(BHDR(bs->bh)->h_hash);
 849
 850                         /*
 851                          * This must happen under buffer lock for
 852                          * ext4_xattr_block_set() to reliably detect modified
 853                          * block
 854                          */
 855                         mb_cache_entry_delete_block(ext4_mb_cache, hash,
 856                                                     bs->bh->b_blocknr);
 857                         ea_bdebug(bs->bh, "modifying in-place");
 858                         error = ext4_xattr_set_entry(i, s);
 859                         if (!error) {
 860                                 if (!IS_LAST_ENTRY(s->first))
 861                                         ext4_xattr_rehash(header(s->base),
 862                                                           s->here);
 863                                 ext4_xattr_cache_insert(ext4_mb_cache,
 864                                         bs->bh);
 865                         }
 866                         unlock_buffer(bs->bh);
 867                         if (error == -EFSCORRUPTED)
 868                                 goto bad_block;
 869                         if (!error)
 870                                 error = ext4_handle_dirty_xattr_block(handle,
 871                                                                       inode,
 872                                                                       bs->bh);
 873                         if (error)
 874                                 goto cleanup;
 875                         goto inserted;
 876                 } else {
 877                         int offset = (char *)s->here - bs->bh->b_data;
 878
 879                         unlock_buffer(bs->bh);
 880                         ea_bdebug(bs->bh, "cloning");
 881                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
 882                         error = -ENOMEM;
 883                         if (s->base == NULL)
 884                                 goto cleanup;
 885                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 886                         s->first = ENTRY(header(s->base)+1);
 887                         header(s->base)->h_refcount = cpu_to_le32(1);
 888                         s->here = ENTRY(s->base + offset);
 889                         s->end = s->base + bs->bh->b_size;
 890                 }
 891         } else {
 892                 /* Allocate a buffer where we construct the new block. */
 893                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
 894                 /* assert(header == s->base) */
 895                 error = -ENOMEM;
 896                 if (s->base == NULL)
 897                         goto cleanup;
 898                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
 899                 header(s->base)->h_blocks = cpu_to_le32(1);
 900                 header(s->base)->h_refcount = cpu_to_le32(1);
 901                 s->first = ENTRY(header(s->base)+1);
 902                 s->here = ENTRY(header(s->base)+1);
 903                 s->end = s->base + sb->s_blocksize;
 904         }
 905
 906         error = ext4_xattr_set_entry(i, s);
 907         if (error == -EFSCORRUPTED)
 908                 goto bad_block;
 909         if (error)
 910                 goto cleanup;
 911         if (!IS_LAST_ENTRY(s->first))
 912                 ext4_xattr_rehash(header(s->base), s->here);
 913
 914 inserted:
 915         if (!IS_LAST_ENTRY(s->first)) {
 916                 new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);
 917                 if (new_bh) {
 918                         /* We found an identical block in the cache. */
 919                         if (new_bh == bs->bh)
 920                                 ea_bdebug(new_bh, "keeping");
 921                         else {
 922                                 u32 ref;
 923
 924                                 /* The old block is released after updating
 925                                    the inode. */
 926                                 error = dquot_alloc_block(inode,
 927                                                 EXT4_C2B(EXT4_SB(sb), 1));
 928                                 if (error)
 929                                         goto cleanup;
 930                                 BUFFER_TRACE(new_bh, "get_write_access");
 931                                 error = ext4_journal_get_write_access(handle,
 932                                                                       new_bh);
 933                                 if (error)
 934                                         goto cleanup_dquot;
 935                                 lock_buffer(new_bh);
 936                                 /*
 937                                  * We have to be careful about races with
 938                                  * freeing, rehashing or adding references to
 939                                  * xattr block. Once we hold buffer lock xattr
 940                                  * block's state is stable so we can check
 941                                  * whether the block got freed / rehashed or
 942                                  * not.  Since we unhash mbcache entry under
 943                                  * buffer lock when freeing / rehashing xattr
 944                                  * block, checking whether entry is still
 945                                  * hashed is reliable. Same rules hold for
 946                                  * e_reusable handling.
 947                                  */
 948                                 if (hlist_bl_unhashed(&ce->e_hash_list) ||
 949                                     !ce->e_reusable) {
 950                                         /*
 951                                          * Undo everything and check mbcache
 952                                          * again.
 953                                          */
 954                                         unlock_buffer(new_bh);
 955                                         dquot_free_block(inode,
 956                                                          EXT4_C2B(EXT4_SB(sb),
 957                                                                   1));
 958                                         brelse(new_bh);
 959                                         mb_cache_entry_put(ext4_mb_cache, ce);
 960                                         ce = NULL;
 961                                         new_bh = NULL;
 962                                         goto inserted;
 963                                 }
 964                                 ref = le32_to_cpu(BHDR(new_bh)->h_refcount) + 1;
 965                                 BHDR(new_bh)->h_refcount = cpu_to_le32(ref);
 966                                 if (ref >= EXT4_XATTR_REFCOUNT_MAX)
 967                                         ce->e_reusable = 0;
 968                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
 969                                           ref);
 970                                 unlock_buffer(new_bh);
 971                                 error = ext4_handle_dirty_xattr_block(handle,
 972                                                                       inode,
 973                                                                       new_bh);
 974                                 if (error)
 975                                         goto cleanup_dquot;
 976                         }
 977                         mb_cache_entry_touch(ext4_mb_cache, ce);
 978                         mb_cache_entry_put(ext4_mb_cache, ce);
 979                         ce = NULL;
 980                 } else if (bs->bh && s->base == bs->bh->b_data) {
 981                         /* We were modifying this block in-place. */
 982                         ea_bdebug(bs->bh, "keeping this block");
 983                         new_bh = bs->bh;
 984                         get_bh(new_bh);
 985                 } else {
 986                         /* We need to allocate a new block */
 987                         ext4_fsblk_t goal, block;
 988
 989                         goal = ext4_group_first_block_no(sb,
 990                                                 EXT4_I(inode)->i_block_group);
 991
 992                         /* non-extent files can't have physical blocks past 2^32 */
 993                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 994                                 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
 995
 996                         block = ext4_new_meta_blocks(handle, inode, goal, 0,
 997                                                      NULL, &error);
 998                         if (error)
 999                                 goto cleanup;
1000
1001                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
1002                                 BUG_ON(block > EXT4_MAX_BLOCK_FILE_PHYS);
1003
1004                         ea_idebug(inode, "creating block %llu",
1005                                   (unsigned long long)block);
1006
1007                         new_bh = sb_getblk(sb, block);
1008                         if (unlikely(!new_bh)) {
1009                                 error = -ENOMEM;
1010 getblk_failed:
1011                                 ext4_free_blocks(handle, inode, NULL, block, 1,
1012                                                  EXT4_FREE_BLOCKS_METADATA);
1013                                 goto cleanup;
1014                         }
1015                         lock_buffer(new_bh);
1016                         error = ext4_journal_get_create_access(handle, new_bh);
1017                         if (error) {
1018                                 unlock_buffer(new_bh);
1019                                 error = -EIO;
1020                                 goto getblk_failed;
1021                         }
1022                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
1023                         set_buffer_uptodate(new_bh);
1024                         unlock_buffer(new_bh);
1025                         ext4_xattr_cache_insert(ext4_mb_cache, new_bh);
1026                         error = ext4_handle_dirty_xattr_block(handle,
1027                                                               inode, new_bh);
1028                         if (error)
1029                                 goto cleanup;
1030                 }
1031         }
1032
1033         /* Update the inode. */
1034         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
1035
1036         /* Drop the previous xattr block. */
1037         if (bs->bh && bs->bh != new_bh)
1038                 ext4_xattr_release_block(handle, inode, bs->bh);
1039         error = 0;
1040
1041 cleanup:
1042         if (ce)
1043                 mb_cache_entry_put(ext4_mb_cache, ce);
1044         brelse(new_bh);
1045         if (!(bs->bh && s->base == bs->bh->b_data))
1046                 kfree(s->base);
1047
1048         return error;
1049
1050 cleanup_dquot:
1051         dquot_free_block(inode, EXT4_C2B(EXT4_SB(sb), 1));
1052         goto cleanup;
1053
1054 bad_block:
1055         EXT4_ERROR_INODE(inode, "bad block %llu",
1056                          EXT4_I(inode)->i_file_acl);
1057         goto cleanup;
1058
1059 #undef header
1060 }
1061
1062 int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
1063                           struct ext4_xattr_ibody_find *is)
1064 {
1065         struct ext4_xattr_ibody_header *header;
1066         struct ext4_inode *raw_inode;
1067         int error;
1068
1069         if (EXT4_I(inode)->i_extra_isize == 0)
1070                 return 0;
1071         raw_inode = ext4_raw_inode(&is->iloc);
1072         header = IHDR(inode, raw_inode);
1073         is->s.base = is->s.first = IFIRST(header);
1074         is->s.here = is->s.first;
1075         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
1076         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
1077                 error = xattr_check_inode(inode, header, is->s.end);
1078                 if (error)
1079                         return error;
1080                 /* Find the named attribute. */
1081                 error = ext4_xattr_find_entry(&is->s.here, i->name_index,
1082                                               i->name, is->s.end -
1083                                               (void *)is->s.base, 0);
1084                 if (error && error != -ENODATA)
1085                         return error;
1086                 is->s.not_found = error;
1087         }
1088         return 0;
1089 }
1090
1091 int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode,
1092                                 struct ext4_xattr_info *i,
1093                                 struct ext4_xattr_ibody_find *is)
1094 {
1095         struct ext4_xattr_ibody_header *header;
1096         struct ext4_xattr_search *s = &is->s;
1097         int error;
1098
1099         if (EXT4_I(inode)->i_extra_isize == 0)
1100                 return -ENOSPC;
1101         error = ext4_xattr_set_entry(i, s);
1102         if (error) {
1103                 if (error == -ENOSPC &&
1104                     ext4_has_inline_data(inode)) {
1105                         error = ext4_try_to_evict_inline_data(handle, inode,
1106                                         EXT4_XATTR_LEN(strlen(i->name) +
1107                                         EXT4_XATTR_SIZE(i->value_len)));
1108                         if (error)
1109                                 return error;
1110                         error = ext4_xattr_ibody_find(inode, i, is);
1111                         if (error)
1112                                 return error;
1113                         error = ext4_xattr_set_entry(i, s);
1114                 }
1115                 if (error)
1116                         return error;
1117         }
1118         header = IHDR(inode, ext4_raw_inode(&is->iloc));
1119         if (!IS_LAST_ENTRY(s->first)) {
1120                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1121                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
1122         } else {
1123                 header->h_magic = cpu_to_le32(0);
1124                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
1125         }
1126         return 0;
1127 }
1128
1129 static int ext4_xattr_ibody_set(struct inode *inode,
1130                                 struct ext4_xattr_info *i,
1131                                 struct ext4_xattr_ibody_find *is)
1132 {
1133         struct ext4_xattr_ibody_header *header;
1134         struct ext4_xattr_search *s = &is->s;
1135         int error;
1136
1137         if (EXT4_I(inode)->i_extra_isize == 0)
1138                 return -ENOSPC;
1139         error = ext4_xattr_set_entry(i, s);
1140         if (error)
1141                 return error;
1142         header = IHDR(inode, ext4_raw_inode(&is->iloc));
1143         if (!IS_LAST_ENTRY(s->first)) {
1144                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1145                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
1146         } else {
1147                 header->h_magic = cpu_to_le32(0);
1148                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
1149         }
1150         return 0;
1151 }
1152
1153 static int ext4_xattr_value_same(struct ext4_xattr_search *s,
1154                                  struct ext4_xattr_info *i)
1155 {
1156         void *value;
1157
1158         if (le32_to_cpu(s->here->e_value_size) != i->value_len)
1159                 return 0;
1160         value = ((void *)s->base) + le16_to_cpu(s->here->e_value_offs);
1161         return !memcmp(value, i->value, i->value_len);
1162 }
1163
1164 /*
1165  * ext4_xattr_set_handle()
1166  *
1167  * Create, replace or remove an extended attribute for this inode.  Value
1168  * is NULL to remove an existing extended attribute, and non-NULL to
1169  * either replace an existing extended attribute, or create a new extended
1170  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
1171  * specify that an extended attribute must exist and must not exist
1172  * previous to the call, respectively.
1173  *
1174  * Returns 0, or a negative error number on failure.
1175  */
1176 int
1177 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
1178                       const char *name, const void *value, size_t value_len,
1179                       int flags)
1180 {
1181         struct ext4_xattr_info i = {
1182                 .name_index = name_index,
1183                 .name = name,
1184                 .value = value,
1185                 .value_len = value_len,
1186
1187         };
1188         struct ext4_xattr_ibody_find is = {
1189                 .s = { .not_found = -ENODATA, },
1190         };
1191         struct ext4_xattr_block_find bs = {
1192                 .s = { .not_found = -ENODATA, },
1193         };
1194         int no_expand;
1195         int error;
1196
1197         if (!name)
1198                 return -EINVAL;
1199         if (strlen(name) > 255)
1200                 return -ERANGE;
1201         ext4_write_lock_xattr(inode, &no_expand);
1202
1203         error = ext4_reserve_inode_write(handle, inode, &is.iloc);
1204         if (error)
1205                 goto cleanup;
1206
1207         if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) {
1208                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
1209                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
1210                 ext4_clear_inode_state(inode, EXT4_STATE_NEW);
1211         }
1212
1213         error = ext4_xattr_ibody_find(inode, &i, &is);
1214         if (error)
1215                 goto cleanup;
1216         if (is.s.not_found)
1217                 error = ext4_xattr_block_find(inode, &i, &bs);
1218         if (error)
1219                 goto cleanup;
1220         if (is.s.not_found && bs.s.not_found) {
1221                 error = -ENODATA;
1222                 if (flags & XATTR_REPLACE)
1223                         goto cleanup;
1224                 error = 0;
1225                 if (!value)
1226                         goto cleanup;
1227         } else {
1228                 error = -EEXIST;
1229                 if (flags & XATTR_CREATE)
1230                         goto cleanup;
1231         }
1232         if (!value) {
1233                 if (!is.s.not_found)
1234                         error = ext4_xattr_ibody_set(inode, &i, &is);
1235                 else if (!bs.s.not_found)
1236                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1237         } else {
1238                 error = 0;
1239                 /* Xattr value did not change? Save us some work and bail out */
1240                 if (!is.s.not_found && ext4_xattr_value_same(&is.s, &i))
1241                         goto cleanup;
1242                 if (!bs.s.not_found && ext4_xattr_value_same(&bs.s, &i))
1243                         goto cleanup;
1244
1245                 error = ext4_xattr_ibody_set(inode, &i, &is);
1246                 if (!error && !bs.s.not_found) {
1247                         i.value = NULL;
1248                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1249                 } else if (error == -ENOSPC) {
1250                         if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
1251                                 error = ext4_xattr_block_find(inode, &i, &bs);
1252                                 if (error)
1253                                         goto cleanup;
1254                         }
1255                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1256                         if (error)
1257                                 goto cleanup;
1258                         if (!is.s.not_found) {
1259                                 i.value = NULL;
1260                                 error = ext4_xattr_ibody_set(inode, &i, &is);
1261                         }
1262                 }
1263         }
1264         if (!error) {
1265                 ext4_xattr_update_super_block(handle, inode->i_sb);
1266                 inode->i_ctime = current_time(inode);
1267                 if (!value)
1268                         no_expand = 0;
1269                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
1270                 /*
1271                  * The bh is consumed by ext4_mark_iloc_dirty, even with
1272                  * error != 0.
1273                  */
1274                 is.iloc.bh = NULL;
1275                 if (IS_SYNC(inode))
1276                         ext4_handle_sync(handle);
1277         }
1278
1279 cleanup:
1280         brelse(is.iloc.bh);
1281         brelse(bs.bh);
1282         ext4_write_unlock_xattr(inode, &no_expand);
1283         return error;
1284 }
1285
1286 /*
1287  * ext4_xattr_set()
1288  *
1289  * Like ext4_xattr_set_handle, but start from an inode. This extended
1290  * attribute modification is a filesystem transaction by itself.
1291  *
1292  * Returns 0, or a negative error number on failure.
1293  */
1294 int
1295 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
1296                const void *value, size_t value_len, int flags)
1297 {
1298         handle_t *handle;
1299         int error, retries = 0;
1300         int credits = ext4_jbd2_credits_xattr(inode);
1301
1302 retry:
1303         handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
1304         if (IS_ERR(handle)) {
1305                 error = PTR_ERR(handle);
1306         } else {
1307                 int error2;
1308
1309                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
1310                                               value, value_len, flags);
1311                 error2 = ext4_journal_stop(handle);
1312                 if (error == -ENOSPC &&
1313                     ext4_should_retry_alloc(inode->i_sb, &retries))
1314                         goto retry;
1315                 if (error == 0)
1316                         error = error2;
1317         }
1318
1319         return error;
1320 }
1321
1322 /*
1323  * Shift the EA entries in the inode to create space for the increased
1324  * i_extra_isize.
1325  */
1326 static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
1327                                      int value_offs_shift, void *to,
1328                                      void *from, size_t n)
1329 {
1330         struct ext4_xattr_entry *last = entry;
1331         int new_offs;
1332
1333         /* We always shift xattr headers further thus offsets get lower */
1334         BUG_ON(value_offs_shift > 0);
1335
1336         /* Adjust the value offsets of the entries */
1337         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1338                 if (last->e_value_size) {
1339                         new_offs = le16_to_cpu(last->e_value_offs) +
1340                                                         value_offs_shift;
1341                         last->e_value_offs = cpu_to_le16(new_offs);
1342                 }
1343         }
1344         /* Shift the entries by n bytes */
1345         memmove(to, from, n);
1346 }
1347
1348 /*
1349  * Move xattr pointed to by 'entry' from inode into external xattr block
1350  */
1351 static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode,
1352                                     struct ext4_inode *raw_inode,
1353                                     struct ext4_xattr_entry *entry)
1354 {
1355         struct ext4_xattr_ibody_find *is = NULL;
1356         struct ext4_xattr_block_find *bs = NULL;
1357         char *buffer = NULL, *b_entry_name = NULL;
1358         size_t value_offs, value_size;
1359         struct ext4_xattr_info i = {
1360                 .value = NULL,
1361                 .value_len = 0,
1362                 .name_index = entry->e_name_index,
1363         };
1364         struct ext4_xattr_ibody_header *header = IHDR(inode, raw_inode);
1365         int error;
1366
1367         value_offs = le16_to_cpu(entry->e_value_offs);
1368         value_size = le32_to_cpu(entry->e_value_size);
1369
1370         is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
1371         bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
1372         buffer = kmalloc(value_size, GFP_NOFS);
1373         b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
1374         if (!is || !bs || !buffer || !b_entry_name) {
1375                 error = -ENOMEM;
1376                 goto out;
1377         }
1378
1379         is->s.not_found = -ENODATA;
1380         bs->s.not_found = -ENODATA;
1381         is->iloc.bh = NULL;
1382         bs->bh = NULL;
1383
1384         /* Save the entry name and the entry value */
1385         memcpy(buffer, (void *)IFIRST(header) + value_offs, value_size);
1386         memcpy(b_entry_name, entry->e_name, entry->e_name_len);
1387         b_entry_name[entry->e_name_len] = '\0';
1388         i.name = b_entry_name;
1389
1390         error = ext4_get_inode_loc(inode, &is->iloc);
1391         if (error)
1392                 goto out;
1393
1394         error = ext4_xattr_ibody_find(inode, &i, is);
1395         if (error)
1396                 goto out;
1397
1398         /* Remove the chosen entry from the inode */
1399         error = ext4_xattr_ibody_set(inode, &i, is);
1400         if (error)
1401                 goto out;
1402
1403         i.name = b_entry_name;
1404         i.value = buffer;
1405         i.value_len = value_size;
1406         error = ext4_xattr_block_find(inode, &i, bs);
1407         if (error)
1408                 goto out;
1409
1410         /* Add entry which was removed from the inode into the block */
1411         error = ext4_xattr_block_set(handle, inode, &i, bs);
1412         if (error)
1413                 goto out;
1414         error = 0;
1415 out:
1416         kfree(b_entry_name);
1417         kfree(buffer);
1418         if (is)
1419                 brelse(is->iloc.bh);
1420         kfree(is);
1421         kfree(bs);
1422
1423         return error;
1424 }
1425
1426 static int ext4_xattr_make_inode_space(handle_t *handle, struct inode *inode,
1427                                        struct ext4_inode *raw_inode,
1428                                        int isize_diff, size_t ifree,
1429                                        size_t bfree, int *total_ino)
1430 {
1431         struct ext4_xattr_ibody_header *header = IHDR(inode, raw_inode);
1432         struct ext4_xattr_entry *small_entry;
1433         struct ext4_xattr_entry *entry;
1434         struct ext4_xattr_entry *last;
1435         unsigned int entry_size;        /* EA entry size */
1436         unsigned int total_size;        /* EA entry size + value size */
1437         unsigned int min_total_size;
1438         int error;
1439
1440         while (isize_diff > ifree) {
1441                 entry = NULL;
1442                 small_entry = NULL;
1443                 min_total_size = ~0U;
1444                 last = IFIRST(header);
1445                 /* Find the entry best suited to be pushed into EA block */
1446                 for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1447                         total_size =
1448                         EXT4_XATTR_SIZE(le32_to_cpu(last->e_value_size)) +
1449                                         EXT4_XATTR_LEN(last->e_name_len);
1450                         if (total_size <= bfree &&
1451                             total_size < min_total_size) {
1452                                 if (total_size + ifree < isize_diff) {
1453                                         small_entry = last;
1454                                 } else {
1455                                         entry = last;
1456                                         min_total_size = total_size;
1457                                 }
1458                         }
1459                 }
1460
1461                 if (entry == NULL) {
1462                         if (small_entry == NULL)
1463                                 return -ENOSPC;
1464                         entry = small_entry;
1465                 }
1466
1467                 entry_size = EXT4_XATTR_LEN(entry->e_name_len);
1468                 total_size = entry_size +
1469                         EXT4_XATTR_SIZE(le32_to_cpu(entry->e_value_size));
1470                 error = ext4_xattr_move_to_block(handle, inode, raw_inode,
1471                                                  entry);
1472                 if (error)
1473                         return error;
1474
1475                 *total_ino -= entry_size;
1476                 ifree += total_size;
1477                 bfree -= total_size;
1478         }
1479
1480         return 0;
1481 }
1482
1483 /*
1484  * Expand an inode by new_extra_isize bytes when EAs are present.
1485  * Returns 0 on success or negative error number on failure.
1486  */
1487 int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
1488                                struct ext4_inode *raw_inode, handle_t *handle)
1489 {
1490         struct ext4_xattr_ibody_header *header;
1491         struct buffer_head *bh = NULL;
1492         size_t min_offs;
1493         size_t ifree, bfree;
1494         int total_ino;
1495         void *base, *end;
1496         int error = 0, tried_min_extra_isize = 0;
1497         int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize);
1498         int isize_diff; /* How much do we need to grow i_extra_isize */
1499         int no_expand;
1500
1501         if (ext4_write_trylock_xattr(inode, &no_expand) == 0)
1502                 return 0;
1503
1504 retry:
1505         isize_diff = new_extra_isize - EXT4_I(inode)->i_extra_isize;
1506         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
1507                 goto out;
1508
1509         header = IHDR(inode, raw_inode);
1510
1511         /*
1512          * Check if enough free space is available in the inode to shift the
1513          * entries ahead by new_extra_isize.
1514          */
1515
1516         base = IFIRST(header);
1517         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
1518         min_offs = end - base;
1519         total_ino = sizeof(struct ext4_xattr_ibody_header);
1520
1521         error = xattr_check_inode(inode, header, end);
1522         if (error)
1523                 goto cleanup;
1524
1525         ifree = ext4_xattr_free_space(base, &min_offs, base, &total_ino);
1526         if (ifree >= isize_diff)
1527                 goto shift;
1528
1529         /*
1530          * Enough free space isn't available in the inode, check if
1531          * EA block can hold new_extra_isize bytes.
1532          */
1533         if (EXT4_I(inode)->i_file_acl) {
1534                 bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1535                 error = -EIO;
1536                 if (!bh)
1537                         goto cleanup;
1538                 if (ext4_xattr_check_block(inode, bh)) {
1539                         EXT4_ERROR_INODE(inode, "bad block %llu",
1540                                          EXT4_I(inode)->i_file_acl);
1541                         error = -EFSCORRUPTED;
1542                         goto cleanup;
1543                 }
1544                 base = BHDR(bh);
1545                 end = bh->b_data + bh->b_size;
1546                 min_offs = end - base;
1547                 bfree = ext4_xattr_free_space(BFIRST(bh), &min_offs, base,
1548                                               NULL);
1549                 if (bfree + ifree < isize_diff) {
1550                         if (!tried_min_extra_isize && s_min_extra_isize) {
1551                                 tried_min_extra_isize++;
1552                                 new_extra_isize = s_min_extra_isize;
1553                                 brelse(bh);
1554                                 goto retry;
1555                         }
1556                         error = -ENOSPC;
1557                         goto cleanup;
1558                 }
1559         } else {
1560                 bfree = inode->i_sb->s_blocksize;
1561         }
1562
1563         error = ext4_xattr_make_inode_space(handle, inode, raw_inode,
1564                                             isize_diff, ifree, bfree,
1565                                             &total_ino);
1566         if (error) {
1567                 if (error == -ENOSPC && !tried_min_extra_isize &&
1568                     s_min_extra_isize) {
1569                         tried_min_extra_isize++;
1570                         new_extra_isize = s_min_extra_isize;
1571                         brelse(bh);
1572                         goto retry;
1573                 }
1574                 goto cleanup;
1575         }
1576 shift:
1577         /* Adjust the offsets and shift the remaining entries ahead */
1578         ext4_xattr_shift_entries(IFIRST(header), EXT4_I(inode)->i_extra_isize
1579                         - new_extra_isize, (void *)raw_inode +
1580                         EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
1581                         (void *)header, total_ino);
1582         EXT4_I(inode)->i_extra_isize = new_extra_isize;
1583         brelse(bh);
1584 out:
1585         ext4_write_unlock_xattr(inode, &no_expand);
1586         return 0;
1587
1588 cleanup:
1589         brelse(bh);
1590         /*
1591          * Inode size expansion failed; don't try again
1592          */
1593         no_expand = 1;
1594         ext4_write_unlock_xattr(inode, &no_expand);
1595         return error;
1596 }
1597
1598
1599
1600 /*
1601  * ext4_xattr_delete_inode()
1602  *
1603  * Free extended attribute resources associated with this inode. This
1604  * is called immediately before an inode is freed. We have exclusive
1605  * access to the inode.
1606  */
1607 void
1608 ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)
1609 {
1610         struct buffer_head *bh = NULL;
1611
1612         if (!EXT4_I(inode)->i_file_acl)
1613                 goto cleanup;
1614         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1615         if (!bh) {
1616                 EXT4_ERROR_INODE(inode, "block %llu read error",
1617                                  EXT4_I(inode)->i_file_acl);
1618                 goto cleanup;
1619         }
1620         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
1621             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1622                 EXT4_ERROR_INODE(inode, "bad block %llu",
1623                                  EXT4_I(inode)->i_file_acl);
1624                 goto cleanup;
1625         }
1626         ext4_xattr_release_block(handle, inode, bh);
1627         EXT4_I(inode)->i_file_acl = 0;
1628
1629 cleanup:
1630         brelse(bh);
1631 }
1632
1633 /*
1634  * ext4_xattr_cache_insert()
1635  *
1636  * Create a new entry in the extended attribute cache, and insert
1637  * it unless such an entry is already in the cache.
1638  *
1639  * Returns 0, or a negative error number on failure.
1640  */
1641 static void
1642 ext4_xattr_cache_insert(struct mb_cache *ext4_mb_cache, struct buffer_head *bh)
1643 {
1644         struct ext4_xattr_header *header = BHDR(bh);
1645         __u32 hash = le32_to_cpu(header->h_hash);
1646         int reusable = le32_to_cpu(header->h_refcount) <
1647                        EXT4_XATTR_REFCOUNT_MAX;
1648         int error;
1649
1650         error = mb_cache_entry_create(ext4_mb_cache, GFP_NOFS, hash,
1651                                       bh->b_blocknr, reusable);
1652         if (error) {
1653                 if (error == -EBUSY)
1654                         ea_bdebug(bh, "already in cache");
1655         } else
1656                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1657 }
1658
1659 /*
1660  * ext4_xattr_cmp()
1661  *
1662  * Compare two extended attribute blocks for equality.
1663  *
1664  * Returns 0 if the blocks are equal, 1 if they differ, and
1665  * a negative error number on errors.
1666  */
1667 static int
1668 ext4_xattr_cmp(struct ext4_xattr_header *header1,
1669                struct ext4_xattr_header *header2)
1670 {
1671         struct ext4_xattr_entry *entry1, *entry2;
1672
1673         entry1 = ENTRY(header1+1);
1674         entry2 = ENTRY(header2+1);
1675         while (!IS_LAST_ENTRY(entry1)) {
1676                 if (IS_LAST_ENTRY(entry2))
1677                         return 1;
1678                 if (entry1->e_hash != entry2->e_hash ||
1679                     entry1->e_name_index != entry2->e_name_index ||
1680                     entry1->e_name_len != entry2->e_name_len ||
1681                     entry1->e_value_size != entry2->e_value_size ||
1682                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1683                         return 1;
1684                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1685                         return -EFSCORRUPTED;
1686                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1687                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1688                            le32_to_cpu(entry1->e_value_size)))
1689                         return 1;
1690
1691                 entry1 = EXT4_XATTR_NEXT(entry1);
1692                 entry2 = EXT4_XATTR_NEXT(entry2);
1693         }
1694         if (!IS_LAST_ENTRY(entry2))
1695                 return 1;
1696         return 0;
1697 }
1698
1699 /*
1700  * ext4_xattr_cache_find()
1701  *
1702  * Find an identical extended attribute block.
1703  *
1704  * Returns a pointer to the block found, or NULL if such a block was
1705  * not found or an error occurred.
1706  */
1707 static struct buffer_head *
1708 ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
1709                       struct mb_cache_entry **pce)
1710 {
1711         __u32 hash = le32_to_cpu(header->h_hash);
1712         struct mb_cache_entry *ce;
1713         struct mb_cache *ext4_mb_cache = EXT4_GET_MB_CACHE(inode);
1714
1715         if (!header->h_hash)
1716                 return NULL;  /* never share */
1717         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1718         ce = mb_cache_entry_find_first(ext4_mb_cache, hash);
1719         while (ce) {
1720                 struct buffer_head *bh;
1721
1722                 bh = sb_bread(inode->i_sb, ce->e_block);
1723                 if (!bh) {
1724                         EXT4_ERROR_INODE(inode, "block %lu read error",
1725                                          (unsigned long) ce->e_block);
1726                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
1727                         *pce = ce;
1728                         return bh;
1729                 }
1730                 brelse(bh);
1731                 ce = mb_cache_entry_find_next(ext4_mb_cache, ce);
1732         }
1733         return NULL;
1734 }
1735
1736 #define NAME_HASH_SHIFT 5
1737 #define VALUE_HASH_SHIFT 16
1738
1739 /*
1740  * ext4_xattr_hash_entry()
1741  *
1742  * Compute the hash of an extended attribute.
1743  */
1744 static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
1745                                          struct ext4_xattr_entry *entry)
1746 {
1747         __u32 hash = 0;
1748         char *name = entry->e_name;
1749         int n;
1750
1751         for (n = 0; n < entry->e_name_len; n++) {
1752                 hash = (hash << NAME_HASH_SHIFT) ^
1753                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1754                        *name++;
1755         }
1756
1757         if (entry->e_value_size != 0) {
1758                 __le32 *value = (__le32 *)((char *)header +
1759                         le16_to_cpu(entry->e_value_offs));
1760                 for (n = (le32_to_cpu(entry->e_value_size) +
1761                      EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {
1762                         hash = (hash << VALUE_HASH_SHIFT) ^
1763                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1764                                le32_to_cpu(*value++);
1765                 }
1766         }
1767         entry->e_hash = cpu_to_le32(hash);
1768 }
1769
1770 #undef NAME_HASH_SHIFT
1771 #undef VALUE_HASH_SHIFT
1772
1773 #define BLOCK_HASH_SHIFT 16
1774
1775 /*
1776  * ext4_xattr_rehash()
1777  *
1778  * Re-compute the extended attribute hash value after an entry has changed.
1779  */
1780 static void ext4_xattr_rehash(struct ext4_xattr_header *header,
1781                               struct ext4_xattr_entry *entry)
1782 {
1783         struct ext4_xattr_entry *here;
1784         __u32 hash = 0;
1785
1786         ext4_xattr_hash_entry(header, entry);
1787         here = ENTRY(header+1);
1788         while (!IS_LAST_ENTRY(here)) {
1789                 if (!here->e_hash) {
1790                         /* Block is not shared if an entry's hash value == 0 */
1791                         hash = 0;
1792                         break;
1793                 }
1794                 hash = (hash << BLOCK_HASH_SHIFT) ^
1795                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1796                        le32_to_cpu(here->e_hash);
1797                 here = EXT4_XATTR_NEXT(here);
1798         }
1799         header->h_hash = cpu_to_le32(hash);
1800 }
1801
1802 #undef BLOCK_HASH_SHIFT
1803
1804 #define HASH_BUCKET_BITS        10
1805
1806 struct mb_cache *
1807 ext4_xattr_create_cache(void)
1808 {
1809         return mb_cache_create(HASH_BUCKET_BITS);
1810 }
1811
1812 void ext4_xattr_destroy_cache(struct mb_cache *cache)
1813 {
1814         if (cache)
1815                 mb_cache_destroy(cache);
1816 }
1817