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 <linux/rwsem.h>
  59 #include "ext4_jbd2.h"
  60 #include "ext4.h"
  61 #include "xattr.h"
  62 #include "acl.h"
  63
  64 #define BHDR(bh) ((struct ext4_xattr_header *)((bh)->b_data))
  65 #define ENTRY(ptr) ((struct ext4_xattr_entry *)(ptr))
  66 #define BFIRST(bh) ENTRY(BHDR(bh)+1)
  67 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
  68
  69 #ifdef EXT4_XATTR_DEBUG
  70 # define ea_idebug(inode, f...) do { \
  71                 printk(KERN_DEBUG "inode %s:%lu: ", \
  72                         inode->i_sb->s_id, inode->i_ino); \
  73                 printk(f); \
  74                 printk("\n"); \
  75         } while (0)
  76 # define ea_bdebug(bh, f...) do { \
  77                 char b[BDEVNAME_SIZE]; \
  78                 printk(KERN_DEBUG "block %s:%lu: ", \
  79                         bdevname(bh->b_bdev, b), \
  80                         (unsigned long) bh->b_blocknr); \
  81                 printk(f); \
  82                 printk("\n"); \
  83         } while (0)
  84 #else
  85 # define ea_idebug(inode, fmt, ...)     no_printk(fmt, ##__VA_ARGS__)
  86 # define ea_bdebug(bh, fmt, ...)        no_printk(fmt, ##__VA_ARGS__)
  87 #endif
  88
  89 static void ext4_xattr_cache_insert(struct buffer_head *);
  90 static struct buffer_head *ext4_xattr_cache_find(struct inode *,
  91                                                  struct ext4_xattr_header *,
  92                                                  struct mb_cache_entry **);
  93 static void ext4_xattr_rehash(struct ext4_xattr_header *,
  94                               struct ext4_xattr_entry *);
  95 static int ext4_xattr_list(struct dentry *dentry, char *buffer,
  96                            size_t buffer_size);
  97
  98 static struct mb_cache *ext4_xattr_cache;
  99
 100 static const struct xattr_handler *ext4_xattr_handler_map[] = {
 101         [EXT4_XATTR_INDEX_USER]              = &ext4_xattr_user_handler,
 102 #ifdef CONFIG_EXT4_FS_POSIX_ACL
 103         [EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &ext4_xattr_acl_access_handler,
 104         [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext4_xattr_acl_default_handler,
 105 #endif
 106         [EXT4_XATTR_INDEX_TRUSTED]           = &ext4_xattr_trusted_handler,
 107 #ifdef CONFIG_EXT4_FS_SECURITY
 108         [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
 109 #endif
 110 };
 111
 112 const struct xattr_handler *ext4_xattr_handlers[] = {
 113         &ext4_xattr_user_handler,
 114         &ext4_xattr_trusted_handler,
 115 #ifdef CONFIG_EXT4_FS_POSIX_ACL
 116         &ext4_xattr_acl_access_handler,
 117         &ext4_xattr_acl_default_handler,
 118 #endif
 119 #ifdef CONFIG_EXT4_FS_SECURITY
 120         &ext4_xattr_security_handler,
 121 #endif
 122         NULL
 123 };
 124
 125 static __le32 ext4_xattr_block_csum(struct inode *inode,
 126                                     sector_t block_nr,
 127                                     struct ext4_xattr_header *hdr)
 128 {
 129         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 130         struct ext4_inode_info *ei = EXT4_I(inode);
 131         __u32 csum, old;
 132
 133         old = hdr->h_checksum;
 134         hdr->h_checksum = 0;
 135         if (le32_to_cpu(hdr->h_refcount) != 1) {
 136                 block_nr = cpu_to_le64(block_nr);
 137                 csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&block_nr,
 138                                    sizeof(block_nr));
 139         } else
 140                 csum = ei->i_csum_seed;
 141         csum = ext4_chksum(sbi, csum, (__u8 *)hdr,
 142                            EXT4_BLOCK_SIZE(inode->i_sb));
 143         hdr->h_checksum = old;
 144         return cpu_to_le32(csum);
 145 }
 146
 147 static int ext4_xattr_block_csum_verify(struct inode *inode,
 148                                         sector_t block_nr,
 149                                         struct ext4_xattr_header *hdr)
 150 {
 151         if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
 152                 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) &&
 153             (hdr->h_checksum != ext4_xattr_block_csum(inode, block_nr, hdr)))
 154                 return 0;
 155         return 1;
 156 }
 157
 158 static void ext4_xattr_block_csum_set(struct inode *inode,
 159                                       sector_t block_nr,
 160                                       struct ext4_xattr_header *hdr)
 161 {
 162         if (!EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
 163                 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
 164                 return;
 165
 166         hdr->h_checksum = ext4_xattr_block_csum(inode, block_nr, hdr);
 167 }
 168
 169 static inline int ext4_handle_dirty_xattr_block(handle_t *handle,
 170                                                 struct inode *inode,
 171                                                 struct buffer_head *bh)
 172 {
 173         ext4_xattr_block_csum_set(inode, bh->b_blocknr, BHDR(bh));
 174         return ext4_handle_dirty_metadata(handle, inode, bh);
 175 }
 176
 177 static inline const struct xattr_handler *
 178 ext4_xattr_handler(int name_index)
 179 {
 180         const struct xattr_handler *handler = NULL;
 181
 182         if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
 183                 handler = ext4_xattr_handler_map[name_index];
 184         return handler;
 185 }
 186
 187 /*
 188  * Inode operation listxattr()
 189  *
 190  * dentry->d_inode->i_mutex: don't care
 191  */
 192 ssize_t
 193 ext4_listxattr(struct dentry *dentry, char *buffer, size_t size)
 194 {
 195         return ext4_xattr_list(dentry, buffer, size);
 196 }
 197
 198 static int
 199 ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end)
 200 {
 201         while (!IS_LAST_ENTRY(entry)) {
 202                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(entry);
 203                 if ((void *)next >= end)
 204                         return -EIO;
 205                 entry = next;
 206         }
 207         return 0;
 208 }
 209
 210 static inline int
 211 ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh)
 212 {
 213         int error;
 214
 215         if (buffer_verified(bh))
 216                 return 0;
 217
 218         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
 219             BHDR(bh)->h_blocks != cpu_to_le32(1))
 220                 return -EIO;
 221         if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh)))
 222                 return -EIO;
 223         error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
 224         if (!error)
 225                 set_buffer_verified(bh);
 226         return error;
 227 }
 228
 229 static inline int
 230 ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size)
 231 {
 232         size_t value_size = le32_to_cpu(entry->e_value_size);
 233
 234         if (entry->e_value_block != 0 || value_size > size ||
 235             le16_to_cpu(entry->e_value_offs) + value_size > size)
 236                 return -EIO;
 237         return 0;
 238 }
 239
 240 static int
 241 ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
 242                       const char *name, size_t size, int sorted)
 243 {
 244         struct ext4_xattr_entry *entry;
 245         size_t name_len;
 246         int cmp = 1;
 247
 248         if (name == NULL)
 249                 return -EINVAL;
 250         name_len = strlen(name);
 251         entry = *pentry;
 252         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 253                 cmp = name_index - entry->e_name_index;
 254                 if (!cmp)
 255                         cmp = name_len - entry->e_name_len;
 256                 if (!cmp)
 257                         cmp = memcmp(name, entry->e_name, name_len);
 258                 if (cmp <= 0 && (sorted || cmp == 0))
 259                         break;
 260         }
 261         *pentry = entry;
 262         if (!cmp && ext4_xattr_check_entry(entry, size))
 263                         return -EIO;
 264         return cmp ? -ENODATA : 0;
 265 }
 266
 267 static int
 268 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
 269                      void *buffer, size_t buffer_size)
 270 {
 271         struct buffer_head *bh = NULL;
 272         struct ext4_xattr_entry *entry;
 273         size_t size;
 274         int error;
 275
 276         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 277                   name_index, name, buffer, (long)buffer_size);
 278
 279         error = -ENODATA;
 280         if (!EXT4_I(inode)->i_file_acl)
 281                 goto cleanup;
 282         ea_idebug(inode, "reading block %llu",
 283                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 284         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 285         if (!bh)
 286                 goto cleanup;
 287         ea_bdebug(bh, "b_count=%d, refcount=%d",
 288                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 289         if (ext4_xattr_check_block(inode, bh)) {
 290 bad_block:
 291                 EXT4_ERROR_INODE(inode, "bad block %llu",
 292                                  EXT4_I(inode)->i_file_acl);
 293                 error = -EIO;
 294                 goto cleanup;
 295         }
 296         ext4_xattr_cache_insert(bh);
 297         entry = BFIRST(bh);
 298         error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
 299         if (error == -EIO)
 300                 goto bad_block;
 301         if (error)
 302                 goto cleanup;
 303         size = le32_to_cpu(entry->e_value_size);
 304         if (buffer) {
 305                 error = -ERANGE;
 306                 if (size > buffer_size)
 307                         goto cleanup;
 308                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
 309                        size);
 310         }
 311         error = size;
 312
 313 cleanup:
 314         brelse(bh);
 315         return error;
 316 }
 317
 318 static int
 319 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 320                      void *buffer, size_t buffer_size)
 321 {
 322         struct ext4_xattr_ibody_header *header;
 323         struct ext4_xattr_entry *entry;
 324         struct ext4_inode *raw_inode;
 325         struct ext4_iloc iloc;
 326         size_t size;
 327         void *end;
 328         int error;
 329
 330         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 331                 return -ENODATA;
 332         error = ext4_get_inode_loc(inode, &iloc);
 333         if (error)
 334                 return error;
 335         raw_inode = ext4_raw_inode(&iloc);
 336         header = IHDR(inode, raw_inode);
 337         entry = IFIRST(header);
 338         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 339         error = ext4_xattr_check_names(entry, end);
 340         if (error)
 341                 goto cleanup;
 342         error = ext4_xattr_find_entry(&entry, name_index, name,
 343                                       end - (void *)entry, 0);
 344         if (error)
 345                 goto cleanup;
 346         size = le32_to_cpu(entry->e_value_size);
 347         if (buffer) {
 348                 error = -ERANGE;
 349                 if (size > buffer_size)
 350                         goto cleanup;
 351                 memcpy(buffer, (void *)IFIRST(header) +
 352                        le16_to_cpu(entry->e_value_offs), size);
 353         }
 354         error = size;
 355
 356 cleanup:
 357         brelse(iloc.bh);
 358         return error;
 359 }
 360
 361 /*
 362  * ext4_xattr_get()
 363  *
 364  * Copy an extended attribute into the buffer
 365  * provided, or compute the buffer size required.
 366  * Buffer is NULL to compute the size of the buffer required.
 367  *
 368  * Returns a negative error number on failure, or the number of bytes
 369  * used / required on success.
 370  */
 371 int
 372 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
 373                void *buffer, size_t buffer_size)
 374 {
 375         int error;
 376
 377         down_read(&EXT4_I(inode)->xattr_sem);
 378         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
 379                                      buffer_size);
 380         if (error == -ENODATA)
 381                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
 382                                              buffer_size);
 383         up_read(&EXT4_I(inode)->xattr_sem);
 384         return error;
 385 }
 386
 387 static int
 388 ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,
 389                         char *buffer, size_t buffer_size)
 390 {
 391         size_t rest = buffer_size;
 392
 393         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 394                 const struct xattr_handler *handler =
 395                         ext4_xattr_handler(entry->e_name_index);
 396
 397                 if (handler) {
 398                         size_t size = handler->list(dentry, buffer, rest,
 399                                                     entry->e_name,
 400                                                     entry->e_name_len,
 401                                                     handler->flags);
 402                         if (buffer) {
 403                                 if (size > rest)
 404                                         return -ERANGE;
 405                                 buffer += size;
 406                         }
 407                         rest -= size;
 408                 }
 409         }
 410         return buffer_size - rest;
 411 }
 412
 413 static int
 414 ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 415 {
 416         struct inode *inode = dentry->d_inode;
 417         struct buffer_head *bh = NULL;
 418         int error;
 419
 420         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 421                   buffer, (long)buffer_size);
 422
 423         error = 0;
 424         if (!EXT4_I(inode)->i_file_acl)
 425                 goto cleanup;
 426         ea_idebug(inode, "reading block %llu",
 427                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 428         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 429         error = -EIO;
 430         if (!bh)
 431                 goto cleanup;
 432         ea_bdebug(bh, "b_count=%d, refcount=%d",
 433                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 434         if (ext4_xattr_check_block(inode, bh)) {
 435                 EXT4_ERROR_INODE(inode, "bad block %llu",
 436                                  EXT4_I(inode)->i_file_acl);
 437                 error = -EIO;
 438                 goto cleanup;
 439         }
 440         ext4_xattr_cache_insert(bh);
 441         error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);
 442
 443 cleanup:
 444         brelse(bh);
 445
 446         return error;
 447 }
 448
 449 static int
 450 ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 451 {
 452         struct inode *inode = dentry->d_inode;
 453         struct ext4_xattr_ibody_header *header;
 454         struct ext4_inode *raw_inode;
 455         struct ext4_iloc iloc;
 456         void *end;
 457         int error;
 458
 459         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 460                 return 0;
 461         error = ext4_get_inode_loc(inode, &iloc);
 462         if (error)
 463                 return error;
 464         raw_inode = ext4_raw_inode(&iloc);
 465         header = IHDR(inode, raw_inode);
 466         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 467         error = ext4_xattr_check_names(IFIRST(header), end);
 468         if (error)
 469                 goto cleanup;
 470         error = ext4_xattr_list_entries(dentry, IFIRST(header),
 471                                         buffer, buffer_size);
 472
 473 cleanup:
 474         brelse(iloc.bh);
 475         return error;
 476 }
 477
 478 /*
 479  * ext4_xattr_list()
 480  *
 481  * Copy a list of attribute names into the buffer
 482  * provided, or compute the buffer size required.
 483  * Buffer is NULL to compute the size of the buffer required.
 484  *
 485  * Returns a negative error number on failure, or the number of bytes
 486  * used / required on success.
 487  */
 488 static int
 489 ext4_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 490 {
 491         int ret, ret2;
 492
 493         down_read(&EXT4_I(dentry->d_inode)->xattr_sem);
 494         ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size);
 495         if (ret < 0)
 496                 goto errout;
 497         if (buffer) {
 498                 buffer += ret;
 499                 buffer_size -= ret;
 500         }
 501         ret = ext4_xattr_block_list(dentry, buffer, buffer_size);
 502         if (ret < 0)
 503                 goto errout;
 504         ret += ret2;
 505 errout:
 506         up_read(&EXT4_I(dentry->d_inode)->xattr_sem);
 507         return ret;
 508 }
 509
 510 /*
 511  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 512  * not set, set it.
 513  */
 514 static void ext4_xattr_update_super_block(handle_t *handle,
 515                                           struct super_block *sb)
 516 {
 517         if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR))
 518                 return;
 519
 520         if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
 521                 EXT4_SET_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR);
 522                 ext4_handle_dirty_super(handle, sb);
 523         }
 524 }
 525
 526 /*
 527  * Release the xattr block BH: If the reference count is > 1, decrement
 528  * it; otherwise free the block.
 529  */
 530 static void
 531 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
 532                          struct buffer_head *bh)
 533 {
 534         struct mb_cache_entry *ce = NULL;
 535         int error = 0;
 536
 537         ce = mb_cache_entry_get(ext4_xattr_cache, bh->b_bdev, bh->b_blocknr);
 538         error = ext4_journal_get_write_access(handle, bh);
 539         if (error)
 540                 goto out;
 541
 542         lock_buffer(bh);
 543         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
 544                 ea_bdebug(bh, "refcount now=0; freeing");
 545                 if (ce)
 546                         mb_cache_entry_free(ce);
 547                 get_bh(bh);
 548                 ext4_free_blocks(handle, inode, bh, 0, 1,
 549                                  EXT4_FREE_BLOCKS_METADATA |
 550                                  EXT4_FREE_BLOCKS_FORGET);
 551                 unlock_buffer(bh);
 552         } else {
 553                 le32_add_cpu(&BHDR(bh)->h_refcount, -1);
 554                 if (ce)
 555                         mb_cache_entry_release(ce);
 556                 unlock_buffer(bh);
 557                 error = ext4_handle_dirty_xattr_block(handle, inode, bh);
 558                 if (IS_SYNC(inode))
 559                         ext4_handle_sync(handle);
 560                 dquot_free_block(inode, 1);
 561                 ea_bdebug(bh, "refcount now=%d; releasing",
 562                           le32_to_cpu(BHDR(bh)->h_refcount));
 563         }
 564 out:
 565         ext4_std_error(inode->i_sb, error);
 566         return;
 567 }
 568
 569 /*
 570  * Find the available free space for EAs. This also returns the total number of
 571  * bytes used by EA entries.
 572  */
 573 static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
 574                                     size_t *min_offs, void *base, int *total)
 575 {
 576         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 577                 *total += EXT4_XATTR_LEN(last->e_name_len);
 578                 if (!last->e_value_block && last->e_value_size) {
 579                         size_t offs = le16_to_cpu(last->e_value_offs);
 580                         if (offs < *min_offs)
 581                                 *min_offs = offs;
 582                 }
 583         }
 584         return (*min_offs - ((void *)last - base) - sizeof(__u32));
 585 }
 586
 587 struct ext4_xattr_info {
 588         int name_index;
 589         const char *name;
 590         const void *value;
 591         size_t value_len;
 592 };
 593
 594 struct ext4_xattr_search {
 595         struct ext4_xattr_entry *first;
 596         void *base;
 597         void *end;
 598         struct ext4_xattr_entry *here;
 599         int not_found;
 600 };
 601
 602 static int
 603 ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
 604 {
 605         struct ext4_xattr_entry *last;
 606         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
 607
 608         /* Compute min_offs and last. */
 609         last = s->first;
 610         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 611                 if (!last->e_value_block && last->e_value_size) {
 612                         size_t offs = le16_to_cpu(last->e_value_offs);
 613                         if (offs < min_offs)
 614                                 min_offs = offs;
 615                 }
 616         }
 617         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
 618         if (!s->not_found) {
 619                 if (!s->here->e_value_block && s->here->e_value_size) {
 620                         size_t size = le32_to_cpu(s->here->e_value_size);
 621                         free += EXT4_XATTR_SIZE(size);
 622                 }
 623                 free += EXT4_XATTR_LEN(name_len);
 624         }
 625         if (i->value) {
 626                 if (free < EXT4_XATTR_SIZE(i->value_len) ||
 627                     free < EXT4_XATTR_LEN(name_len) +
 628                            EXT4_XATTR_SIZE(i->value_len))
 629                         return -ENOSPC;
 630         }
 631
 632         if (i->value && s->not_found) {
 633                 /* Insert the new name. */
 634                 size_t size = EXT4_XATTR_LEN(name_len);
 635                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
 636                 memmove((void *)s->here + size, s->here, rest);
 637                 memset(s->here, 0, size);
 638                 s->here->e_name_index = i->name_index;
 639                 s->here->e_name_len = name_len;
 640                 memcpy(s->here->e_name, i->name, name_len);
 641         } else {
 642                 if (!s->here->e_value_block && s->here->e_value_size) {
 643                         void *first_val = s->base + min_offs;
 644                         size_t offs = le16_to_cpu(s->here->e_value_offs);
 645                         void *val = s->base + offs;
 646                         size_t size = EXT4_XATTR_SIZE(
 647                                 le32_to_cpu(s->here->e_value_size));
 648
 649                         if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
 650                                 /* The old and the new value have the same
 651                                    size. Just replace. */
 652                                 s->here->e_value_size =
 653                                         cpu_to_le32(i->value_len);
 654                                 memset(val + size - EXT4_XATTR_PAD, 0,
 655                                        EXT4_XATTR_PAD); /* Clear pad bytes. */
 656                                 memcpy(val, i->value, i->value_len);
 657                                 return 0;
 658                         }
 659
 660                         /* Remove the old value. */
 661                         memmove(first_val + size, first_val, val - first_val);
 662                         memset(first_val, 0, size);
 663                         s->here->e_value_size = 0;
 664                         s->here->e_value_offs = 0;
 665                         min_offs += size;
 666
 667                         /* Adjust all value offsets. */
 668                         last = s->first;
 669                         while (!IS_LAST_ENTRY(last)) {
 670                                 size_t o = le16_to_cpu(last->e_value_offs);
 671                                 if (!last->e_value_block &&
 672                                     last->e_value_size && o < offs)
 673                                         last->e_value_offs =
 674                                                 cpu_to_le16(o + size);
 675                                 last = EXT4_XATTR_NEXT(last);
 676                         }
 677                 }
 678                 if (!i->value) {
 679                         /* Remove the old name. */
 680                         size_t size = EXT4_XATTR_LEN(name_len);
 681                         last = ENTRY((void *)last - size);
 682                         memmove(s->here, (void *)s->here + size,
 683                                 (void *)last - (void *)s->here + sizeof(__u32));
 684                         memset(last, 0, size);
 685                 }
 686         }
 687
 688         if (i->value) {
 689                 /* Insert the new value. */
 690                 s->here->e_value_size = cpu_to_le32(i->value_len);
 691                 if (i->value_len) {
 692                         size_t size = EXT4_XATTR_SIZE(i->value_len);
 693                         void *val = s->base + min_offs - size;
 694                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
 695                         memset(val + size - EXT4_XATTR_PAD, 0,
 696                                EXT4_XATTR_PAD); /* Clear the pad bytes. */
 697                         memcpy(val, i->value, i->value_len);
 698                 }
 699         }
 700         return 0;
 701 }
 702
 703 struct ext4_xattr_block_find {
 704         struct ext4_xattr_search s;
 705         struct buffer_head *bh;
 706 };
 707
 708 static int
 709 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
 710                       struct ext4_xattr_block_find *bs)
 711 {
 712         struct super_block *sb = inode->i_sb;
 713         int error;
 714
 715         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
 716                   i->name_index, i->name, i->value, (long)i->value_len);
 717
 718         if (EXT4_I(inode)->i_file_acl) {
 719                 /* The inode already has an extended attribute block. */
 720                 bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);
 721                 error = -EIO;
 722                 if (!bs->bh)
 723                         goto cleanup;
 724                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
 725                         atomic_read(&(bs->bh->b_count)),
 726                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
 727                 if (ext4_xattr_check_block(inode, bs->bh)) {
 728                         EXT4_ERROR_INODE(inode, "bad block %llu",
 729                                          EXT4_I(inode)->i_file_acl);
 730                         error = -EIO;
 731                         goto cleanup;
 732                 }
 733                 /* Find the named attribute. */
 734                 bs->s.base = BHDR(bs->bh);
 735                 bs->s.first = BFIRST(bs->bh);
 736                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
 737                 bs->s.here = bs->s.first;
 738                 error = ext4_xattr_find_entry(&bs->s.here, i->name_index,
 739                                               i->name, bs->bh->b_size, 1);
 740                 if (error && error != -ENODATA)
 741                         goto cleanup;
 742                 bs->s.not_found = error;
 743         }
 744         error = 0;
 745
 746 cleanup:
 747         return error;
 748 }
 749
 750 static int
 751 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
 752                      struct ext4_xattr_info *i,
 753                      struct ext4_xattr_block_find *bs)
 754 {
 755         struct super_block *sb = inode->i_sb;
 756         struct buffer_head *new_bh = NULL;
 757         struct ext4_xattr_search *s = &bs->s;
 758         struct mb_cache_entry *ce = NULL;
 759         int error = 0;
 760
 761 #define header(x) ((struct ext4_xattr_header *)(x))
 762
 763         if (i->value && i->value_len > sb->s_blocksize)
 764                 return -ENOSPC;
 765         if (s->base) {
 766                 ce = mb_cache_entry_get(ext4_xattr_cache, bs->bh->b_bdev,
 767                                         bs->bh->b_blocknr);
 768                 error = ext4_journal_get_write_access(handle, bs->bh);
 769                 if (error)
 770                         goto cleanup;
 771                 lock_buffer(bs->bh);
 772
 773                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 774                         if (ce) {
 775                                 mb_cache_entry_free(ce);
 776                                 ce = NULL;
 777                         }
 778                         ea_bdebug(bs->bh, "modifying in-place");
 779                         error = ext4_xattr_set_entry(i, s);
 780                         if (!error) {
 781                                 if (!IS_LAST_ENTRY(s->first))
 782                                         ext4_xattr_rehash(header(s->base),
 783                                                           s->here);
 784                                 ext4_xattr_cache_insert(bs->bh);
 785                         }
 786                         unlock_buffer(bs->bh);
 787                         if (error == -EIO)
 788                                 goto bad_block;
 789                         if (!error)
 790                                 error = ext4_handle_dirty_xattr_block(handle,
 791                                                                       inode,
 792                                                                       bs->bh);
 793                         if (error)
 794                                 goto cleanup;
 795                         goto inserted;
 796                 } else {
 797                         int offset = (char *)s->here - bs->bh->b_data;
 798
 799                         unlock_buffer(bs->bh);
 800                         ext4_handle_release_buffer(handle, bs->bh);
 801                         if (ce) {
 802                                 mb_cache_entry_release(ce);
 803                                 ce = NULL;
 804                         }
 805                         ea_bdebug(bs->bh, "cloning");
 806                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
 807                         error = -ENOMEM;
 808                         if (s->base == NULL)
 809                                 goto cleanup;
 810                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 811                         s->first = ENTRY(header(s->base)+1);
 812                         header(s->base)->h_refcount = cpu_to_le32(1);
 813                         s->here = ENTRY(s->base + offset);
 814                         s->end = s->base + bs->bh->b_size;
 815                 }
 816         } else {
 817                 /* Allocate a buffer where we construct the new block. */
 818                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
 819                 /* assert(header == s->base) */
 820                 error = -ENOMEM;
 821                 if (s->base == NULL)
 822                         goto cleanup;
 823                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
 824                 header(s->base)->h_blocks = cpu_to_le32(1);
 825                 header(s->base)->h_refcount = cpu_to_le32(1);
 826                 s->first = ENTRY(header(s->base)+1);
 827                 s->here = ENTRY(header(s->base)+1);
 828                 s->end = s->base + sb->s_blocksize;
 829         }
 830
 831         error = ext4_xattr_set_entry(i, s);
 832         if (error == -EIO)
 833                 goto bad_block;
 834         if (error)
 835                 goto cleanup;
 836         if (!IS_LAST_ENTRY(s->first))
 837                 ext4_xattr_rehash(header(s->base), s->here);
 838
 839 inserted:
 840         if (!IS_LAST_ENTRY(s->first)) {
 841                 new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);
 842                 if (new_bh) {
 843                         /* We found an identical block in the cache. */
 844                         if (new_bh == bs->bh)
 845                                 ea_bdebug(new_bh, "keeping");
 846                         else {
 847                                 /* The old block is released after updating
 848                                    the inode. */
 849                                 error = dquot_alloc_block(inode, 1);
 850                                 if (error)
 851                                         goto cleanup;
 852                                 error = ext4_journal_get_write_access(handle,
 853                                                                       new_bh);
 854                                 if (error)
 855                                         goto cleanup_dquot;
 856                                 lock_buffer(new_bh);
 857                                 le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
 858                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
 859                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 860                                 unlock_buffer(new_bh);
 861                                 error = ext4_handle_dirty_xattr_block(handle,
 862                                                                       inode,
 863                                                                       new_bh);
 864                                 if (error)
 865                                         goto cleanup_dquot;
 866                         }
 867                         mb_cache_entry_release(ce);
 868                         ce = NULL;
 869                 } else if (bs->bh && s->base == bs->bh->b_data) {
 870                         /* We were modifying this block in-place. */
 871                         ea_bdebug(bs->bh, "keeping this block");
 872                         new_bh = bs->bh;
 873                         get_bh(new_bh);
 874                 } else {
 875                         /* We need to allocate a new block */
 876                         ext4_fsblk_t goal, block;
 877
 878                         goal = ext4_group_first_block_no(sb,
 879                                                 EXT4_I(inode)->i_block_group);
 880
 881                         /* non-extent files can't have physical blocks past 2^32 */
 882                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 883                                 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
 884
 885                         /*
 886                          * take i_data_sem because we will test
 887                          * i_delalloc_reserved_flag in ext4_mb_new_blocks
 888                          */
 889                         down_read((&EXT4_I(inode)->i_data_sem));
 890                         block = ext4_new_meta_blocks(handle, inode, goal, 0,
 891                                                      NULL, &error);
 892                         up_read((&EXT4_I(inode)->i_data_sem));
 893                         if (error)
 894                                 goto cleanup;
 895
 896                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 897                                 BUG_ON(block > EXT4_MAX_BLOCK_FILE_PHYS);
 898
 899                         ea_idebug(inode, "creating block %llu",
 900                                   (unsigned long long)block);
 901
 902                         new_bh = sb_getblk(sb, block);
 903                         if (!new_bh) {
 904 getblk_failed:
 905                                 ext4_free_blocks(handle, inode, NULL, block, 1,
 906                                                  EXT4_FREE_BLOCKS_METADATA);
 907                                 error = -EIO;
 908                                 goto cleanup;
 909                         }
 910                         lock_buffer(new_bh);
 911                         error = ext4_journal_get_create_access(handle, new_bh);
 912                         if (error) {
 913                                 unlock_buffer(new_bh);
 914                                 goto getblk_failed;
 915                         }
 916                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
 917                         set_buffer_uptodate(new_bh);
 918                         unlock_buffer(new_bh);
 919                         ext4_xattr_cache_insert(new_bh);
 920                         error = ext4_handle_dirty_xattr_block(handle,
 921                                                               inode, new_bh);
 922                         if (error)
 923                                 goto cleanup;
 924                 }
 925         }
 926
 927         /* Update the inode. */
 928         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
 929
 930         /* Drop the previous xattr block. */
 931         if (bs->bh && bs->bh != new_bh)
 932                 ext4_xattr_release_block(handle, inode, bs->bh);
 933         error = 0;
 934
 935 cleanup:
 936         if (ce)
 937                 mb_cache_entry_release(ce);
 938         brelse(new_bh);
 939         if (!(bs->bh && s->base == bs->bh->b_data))
 940                 kfree(s->base);
 941
 942         return error;
 943
 944 cleanup_dquot:
 945         dquot_free_block(inode, 1);
 946         goto cleanup;
 947
 948 bad_block:
 949         EXT4_ERROR_INODE(inode, "bad block %llu",
 950                          EXT4_I(inode)->i_file_acl);
 951         goto cleanup;
 952
 953 #undef header
 954 }
 955
 956 struct ext4_xattr_ibody_find {
 957         struct ext4_xattr_search s;
 958         struct ext4_iloc iloc;
 959 };
 960
 961 static int
 962 ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
 963                       struct ext4_xattr_ibody_find *is)
 964 {
 965         struct ext4_xattr_ibody_header *header;
 966         struct ext4_inode *raw_inode;
 967         int error;
 968
 969         if (EXT4_I(inode)->i_extra_isize == 0)
 970                 return 0;
 971         raw_inode = ext4_raw_inode(&is->iloc);
 972         header = IHDR(inode, raw_inode);
 973         is->s.base = is->s.first = IFIRST(header);
 974         is->s.here = is->s.first;
 975         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 976         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
 977                 error = ext4_xattr_check_names(IFIRST(header), is->s.end);
 978                 if (error)
 979                         return error;
 980                 /* Find the named attribute. */
 981                 error = ext4_xattr_find_entry(&is->s.here, i->name_index,
 982                                               i->name, is->s.end -
 983                                               (void *)is->s.base, 0);
 984                 if (error && error != -ENODATA)
 985                         return error;
 986                 is->s.not_found = error;
 987         }
 988         return 0;
 989 }
 990
 991 static int
 992 ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
 993                      struct ext4_xattr_info *i,
 994                      struct ext4_xattr_ibody_find *is)
 995 {
 996         struct ext4_xattr_ibody_header *header;
 997         struct ext4_xattr_search *s = &is->s;
 998         int error;
 999
1000         if (EXT4_I(inode)->i_extra_isize == 0)
1001                 return -ENOSPC;
1002         error = ext4_xattr_set_entry(i, s);
1003         if (error)
1004                 return error;
1005         header = IHDR(inode, ext4_raw_inode(&is->iloc));
1006         if (!IS_LAST_ENTRY(s->first)) {
1007                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1008                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
1009         } else {
1010                 header->h_magic = cpu_to_le32(0);
1011                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
1012         }
1013         return 0;
1014 }
1015
1016 /*
1017  * ext4_xattr_set_handle()
1018  *
1019  * Create, replace or remove an extended attribute for this inode.  Value
1020  * is NULL to remove an existing extended attribute, and non-NULL to
1021  * either replace an existing extended attribute, or create a new extended
1022  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
1023  * specify that an extended attribute must exist and must not exist
1024  * previous to the call, respectively.
1025  *
1026  * Returns 0, or a negative error number on failure.
1027  */
1028 int
1029 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
1030                       const char *name, const void *value, size_t value_len,
1031                       int flags)
1032 {
1033         struct ext4_xattr_info i = {
1034                 .name_index = name_index,
1035                 .name = name,
1036                 .value = value,
1037                 .value_len = value_len,
1038
1039         };
1040         struct ext4_xattr_ibody_find is = {
1041                 .s = { .not_found = -ENODATA, },
1042         };
1043         struct ext4_xattr_block_find bs = {
1044                 .s = { .not_found = -ENODATA, },
1045         };
1046         unsigned long no_expand;
1047         int error;
1048
1049         if (!name)
1050                 return -EINVAL;
1051         if (strlen(name) > 255)
1052                 return -ERANGE;
1053         down_write(&EXT4_I(inode)->xattr_sem);
1054         no_expand = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
1055         ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
1056
1057         error = ext4_reserve_inode_write(handle, inode, &is.iloc);
1058         if (error)
1059                 goto cleanup;
1060
1061         if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) {
1062                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
1063                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
1064                 ext4_clear_inode_state(inode, EXT4_STATE_NEW);
1065         }
1066
1067         error = ext4_xattr_ibody_find(inode, &i, &is);
1068         if (error)
1069                 goto cleanup;
1070         if (is.s.not_found)
1071                 error = ext4_xattr_block_find(inode, &i, &bs);
1072         if (error)
1073                 goto cleanup;
1074         if (is.s.not_found && bs.s.not_found) {
1075                 error = -ENODATA;
1076                 if (flags & XATTR_REPLACE)
1077                         goto cleanup;
1078                 error = 0;
1079                 if (!value)
1080                         goto cleanup;
1081         } else {
1082                 error = -EEXIST;
1083                 if (flags & XATTR_CREATE)
1084                         goto cleanup;
1085         }
1086         if (!value) {
1087                 if (!is.s.not_found)
1088                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1089                 else if (!bs.s.not_found)
1090                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1091         } else {
1092                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1093                 if (!error && !bs.s.not_found) {
1094                         i.value = NULL;
1095                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1096                 } else if (error == -ENOSPC) {
1097                         if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
1098                                 error = ext4_xattr_block_find(inode, &i, &bs);
1099                                 if (error)
1100                                         goto cleanup;
1101                         }
1102                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1103                         if (error)
1104                                 goto cleanup;
1105                         if (!is.s.not_found) {
1106                                 i.value = NULL;
1107                                 error = ext4_xattr_ibody_set(handle, inode, &i,
1108                                                              &is);
1109                         }
1110                 }
1111         }
1112         if (!error) {
1113                 ext4_xattr_update_super_block(handle, inode->i_sb);
1114                 inode->i_ctime = ext4_current_time(inode);
1115                 if (!value)
1116                         ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1117                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
1118                 /*
1119                  * The bh is consumed by ext4_mark_iloc_dirty, even with
1120                  * error != 0.
1121                  */
1122                 is.iloc.bh = NULL;
1123                 if (IS_SYNC(inode))
1124                         ext4_handle_sync(handle);
1125         }
1126
1127 cleanup:
1128         brelse(is.iloc.bh);
1129         brelse(bs.bh);
1130         if (no_expand == 0)
1131                 ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
1132         up_write(&EXT4_I(inode)->xattr_sem);
1133         return error;
1134 }
1135
1136 /*
1137  * ext4_xattr_set()
1138  *
1139  * Like ext4_xattr_set_handle, but start from an inode. This extended
1140  * attribute modification is a filesystem transaction by itself.
1141  *
1142  * Returns 0, or a negative error number on failure.
1143  */
1144 int
1145 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
1146                const void *value, size_t value_len, int flags)
1147 {
1148         handle_t *handle;
1149         int error, retries = 0;
1150
1151 retry:
1152         handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
1153         if (IS_ERR(handle)) {
1154                 error = PTR_ERR(handle);
1155         } else {
1156                 int error2;
1157
1158                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
1159                                               value, value_len, flags);
1160                 error2 = ext4_journal_stop(handle);
1161                 if (error == -ENOSPC &&
1162                     ext4_should_retry_alloc(inode->i_sb, &retries))
1163                         goto retry;
1164                 if (error == 0)
1165                         error = error2;
1166         }
1167
1168         return error;
1169 }
1170
1171 /*
1172  * Shift the EA entries in the inode to create space for the increased
1173  * i_extra_isize.
1174  */
1175 static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
1176                                      int value_offs_shift, void *to,
1177                                      void *from, size_t n, int blocksize)
1178 {
1179         struct ext4_xattr_entry *last = entry;
1180         int new_offs;
1181
1182         /* Adjust the value offsets of the entries */
1183         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1184                 if (!last->e_value_block && last->e_value_size) {
1185                         new_offs = le16_to_cpu(last->e_value_offs) +
1186                                                         value_offs_shift;
1187                         BUG_ON(new_offs + le32_to_cpu(last->e_value_size)
1188                                  > blocksize);
1189                         last->e_value_offs = cpu_to_le16(new_offs);
1190                 }
1191         }
1192         /* Shift the entries by n bytes */
1193         memmove(to, from, n);
1194 }
1195
1196 /*
1197  * Expand an inode by new_extra_isize bytes when EAs are present.
1198  * Returns 0 on success or negative error number on failure.
1199  */
1200 int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
1201                                struct ext4_inode *raw_inode, handle_t *handle)
1202 {
1203         struct ext4_xattr_ibody_header *header;
1204         struct ext4_xattr_entry *entry, *last, *first;
1205         struct buffer_head *bh = NULL;
1206         struct ext4_xattr_ibody_find *is = NULL;
1207         struct ext4_xattr_block_find *bs = NULL;
1208         char *buffer = NULL, *b_entry_name = NULL;
1209         size_t min_offs, free;
1210         int total_ino, total_blk;
1211         void *base, *start, *end;
1212         int extra_isize = 0, error = 0, tried_min_extra_isize = 0;
1213         int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize);
1214
1215         down_write(&EXT4_I(inode)->xattr_sem);
1216 retry:
1217         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize) {
1218                 up_write(&EXT4_I(inode)->xattr_sem);
1219                 return 0;
1220         }
1221
1222         header = IHDR(inode, raw_inode);
1223         entry = IFIRST(header);
1224
1225         /*
1226          * Check if enough free space is available in the inode to shift the
1227          * entries ahead by new_extra_isize.
1228          */
1229
1230         base = start = entry;
1231         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
1232         min_offs = end - base;
1233         last = entry;
1234         total_ino = sizeof(struct ext4_xattr_ibody_header);
1235
1236         free = ext4_xattr_free_space(last, &min_offs, base, &total_ino);
1237         if (free >= new_extra_isize) {
1238                 entry = IFIRST(header);
1239                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize
1240                                 - new_extra_isize, (void *)raw_inode +
1241                                 EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
1242                                 (void *)header, total_ino,
1243                                 inode->i_sb->s_blocksize);
1244                 EXT4_I(inode)->i_extra_isize = new_extra_isize;
1245                 error = 0;
1246                 goto cleanup;
1247         }
1248
1249         /*
1250          * Enough free space isn't available in the inode, check if
1251          * EA block can hold new_extra_isize bytes.
1252          */
1253         if (EXT4_I(inode)->i_file_acl) {
1254                 bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1255                 error = -EIO;
1256                 if (!bh)
1257                         goto cleanup;
1258                 if (ext4_xattr_check_block(inode, bh)) {
1259                         EXT4_ERROR_INODE(inode, "bad block %llu",
1260                                          EXT4_I(inode)->i_file_acl);
1261                         error = -EIO;
1262                         goto cleanup;
1263                 }
1264                 base = BHDR(bh);
1265                 first = BFIRST(bh);
1266                 end = bh->b_data + bh->b_size;
1267                 min_offs = end - base;
1268                 free = ext4_xattr_free_space(first, &min_offs, base,
1269                                              &total_blk);
1270                 if (free < new_extra_isize) {
1271                         if (!tried_min_extra_isize && s_min_extra_isize) {
1272                                 tried_min_extra_isize++;
1273                                 new_extra_isize = s_min_extra_isize;
1274                                 brelse(bh);
1275                                 goto retry;
1276                         }
1277                         error = -1;
1278                         goto cleanup;
1279                 }
1280         } else {
1281                 free = inode->i_sb->s_blocksize;
1282         }
1283
1284         while (new_extra_isize > 0) {
1285                 size_t offs, size, entry_size;
1286                 struct ext4_xattr_entry *small_entry = NULL;
1287                 struct ext4_xattr_info i = {
1288                         .value = NULL,
1289                         .value_len = 0,
1290                 };
1291                 unsigned int total_size;  /* EA entry size + value size */
1292                 unsigned int shift_bytes; /* No. of bytes to shift EAs by? */
1293                 unsigned int min_total_size = ~0U;
1294
1295                 is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
1296                 bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
1297                 if (!is || !bs) {
1298                         error = -ENOMEM;
1299                         goto cleanup;
1300                 }
1301
1302                 is->s.not_found = -ENODATA;
1303                 bs->s.not_found = -ENODATA;
1304                 is->iloc.bh = NULL;
1305                 bs->bh = NULL;
1306
1307                 last = IFIRST(header);
1308                 /* Find the entry best suited to be pushed into EA block */
1309                 entry = NULL;
1310                 for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1311                         total_size =
1312                         EXT4_XATTR_SIZE(le32_to_cpu(last->e_value_size)) +
1313                                         EXT4_XATTR_LEN(last->e_name_len);
1314                         if (total_size <= free && total_size < min_total_size) {
1315                                 if (total_size < new_extra_isize) {
1316                                         small_entry = last;
1317                                 } else {
1318                                         entry = last;
1319                                         min_total_size = total_size;
1320                                 }
1321                         }
1322                 }
1323
1324                 if (entry == NULL) {
1325                         if (small_entry) {
1326                                 entry = small_entry;
1327                         } else {
1328                                 if (!tried_min_extra_isize &&
1329                                     s_min_extra_isize) {
1330                                         tried_min_extra_isize++;
1331                                         new_extra_isize = s_min_extra_isize;
1332                                         goto retry;
1333                                 }
1334                                 error = -1;
1335                                 goto cleanup;
1336                         }
1337                 }
1338                 offs = le16_to_cpu(entry->e_value_offs);
1339                 size = le32_to_cpu(entry->e_value_size);
1340                 entry_size = EXT4_XATTR_LEN(entry->e_name_len);
1341                 i.name_index = entry->e_name_index,
1342                 buffer = kmalloc(EXT4_XATTR_SIZE(size), GFP_NOFS);
1343                 b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
1344                 if (!buffer || !b_entry_name) {
1345                         error = -ENOMEM;
1346                         goto cleanup;
1347                 }
1348                 /* Save the entry name and the entry value */
1349                 memcpy(buffer, (void *)IFIRST(header) + offs,
1350                        EXT4_XATTR_SIZE(size));
1351                 memcpy(b_entry_name, entry->e_name, entry->e_name_len);
1352                 b_entry_name[entry->e_name_len] = '\0';
1353                 i.name = b_entry_name;
1354
1355                 error = ext4_get_inode_loc(inode, &is->iloc);
1356                 if (error)
1357                         goto cleanup;
1358
1359                 error = ext4_xattr_ibody_find(inode, &i, is);
1360                 if (error)
1361                         goto cleanup;
1362
1363                 /* Remove the chosen entry from the inode */
1364                 error = ext4_xattr_ibody_set(handle, inode, &i, is);
1365                 if (error)
1366                         goto cleanup;
1367
1368                 entry = IFIRST(header);
1369                 if (entry_size + EXT4_XATTR_SIZE(size) >= new_extra_isize)
1370                         shift_bytes = new_extra_isize;
1371                 else
1372                         shift_bytes = entry_size + size;
1373                 /* Adjust the offsets and shift the remaining entries ahead */
1374                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize -
1375                         shift_bytes, (void *)raw_inode +
1376                         EXT4_GOOD_OLD_INODE_SIZE + extra_isize + shift_bytes,
1377                         (void *)header, total_ino - entry_size,
1378                         inode->i_sb->s_blocksize);
1379
1380                 extra_isize += shift_bytes;
1381                 new_extra_isize -= shift_bytes;
1382                 EXT4_I(inode)->i_extra_isize = extra_isize;
1383
1384                 i.name = b_entry_name;
1385                 i.value = buffer;
1386                 i.value_len = size;
1387                 error = ext4_xattr_block_find(inode, &i, bs);
1388                 if (error)
1389                         goto cleanup;
1390
1391                 /* Add entry which was removed from the inode into the block */
1392                 error = ext4_xattr_block_set(handle, inode, &i, bs);
1393                 if (error)
1394                         goto cleanup;
1395                 kfree(b_entry_name);
1396                 kfree(buffer);
1397                 b_entry_name = NULL;
1398                 buffer = NULL;
1399                 brelse(is->iloc.bh);
1400                 kfree(is);
1401                 kfree(bs);
1402         }
1403         brelse(bh);
1404         up_write(&EXT4_I(inode)->xattr_sem);
1405         return 0;
1406
1407 cleanup:
1408         kfree(b_entry_name);
1409         kfree(buffer);
1410         if (is)
1411                 brelse(is->iloc.bh);
1412         kfree(is);
1413         kfree(bs);
1414         brelse(bh);
1415         up_write(&EXT4_I(inode)->xattr_sem);
1416         return error;
1417 }
1418
1419
1420
1421 /*
1422  * ext4_xattr_delete_inode()
1423  *
1424  * Free extended attribute resources associated with this inode. This
1425  * is called immediately before an inode is freed. We have exclusive
1426  * access to the inode.
1427  */
1428 void
1429 ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)
1430 {
1431         struct buffer_head *bh = NULL;
1432
1433         if (!EXT4_I(inode)->i_file_acl)
1434                 goto cleanup;
1435         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1436         if (!bh) {
1437                 EXT4_ERROR_INODE(inode, "block %llu read error",
1438                                  EXT4_I(inode)->i_file_acl);
1439                 goto cleanup;
1440         }
1441         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
1442             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1443                 EXT4_ERROR_INODE(inode, "bad block %llu",
1444                                  EXT4_I(inode)->i_file_acl);
1445                 goto cleanup;
1446         }
1447         ext4_xattr_release_block(handle, inode, bh);
1448         EXT4_I(inode)->i_file_acl = 0;
1449
1450 cleanup:
1451         brelse(bh);
1452 }
1453
1454 /*
1455  * ext4_xattr_put_super()
1456  *
1457  * This is called when a file system is unmounted.
1458  */
1459 void
1460 ext4_xattr_put_super(struct super_block *sb)
1461 {
1462         mb_cache_shrink(sb->s_bdev);
1463 }
1464
1465 /*
1466  * ext4_xattr_cache_insert()
1467  *
1468  * Create a new entry in the extended attribute cache, and insert
1469  * it unless such an entry is already in the cache.
1470  *
1471  * Returns 0, or a negative error number on failure.
1472  */
1473 static void
1474 ext4_xattr_cache_insert(struct buffer_head *bh)
1475 {
1476         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1477         struct mb_cache_entry *ce;
1478         int error;
1479
1480         ce = mb_cache_entry_alloc(ext4_xattr_cache, GFP_NOFS);
1481         if (!ce) {
1482                 ea_bdebug(bh, "out of memory");
1483                 return;
1484         }
1485         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);
1486         if (error) {
1487                 mb_cache_entry_free(ce);
1488                 if (error == -EBUSY) {
1489                         ea_bdebug(bh, "already in cache");
1490                         error = 0;
1491                 }
1492         } else {
1493                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1494                 mb_cache_entry_release(ce);
1495         }
1496 }
1497
1498 /*
1499  * ext4_xattr_cmp()
1500  *
1501  * Compare two extended attribute blocks for equality.
1502  *
1503  * Returns 0 if the blocks are equal, 1 if they differ, and
1504  * a negative error number on errors.
1505  */
1506 static int
1507 ext4_xattr_cmp(struct ext4_xattr_header *header1,
1508                struct ext4_xattr_header *header2)
1509 {
1510         struct ext4_xattr_entry *entry1, *entry2;
1511
1512         entry1 = ENTRY(header1+1);
1513         entry2 = ENTRY(header2+1);
1514         while (!IS_LAST_ENTRY(entry1)) {
1515                 if (IS_LAST_ENTRY(entry2))
1516                         return 1;
1517                 if (entry1->e_hash != entry2->e_hash ||
1518                     entry1->e_name_index != entry2->e_name_index ||
1519                     entry1->e_name_len != entry2->e_name_len ||
1520                     entry1->e_value_size != entry2->e_value_size ||
1521                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1522                         return 1;
1523                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1524                         return -EIO;
1525                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1526                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1527                            le32_to_cpu(entry1->e_value_size)))
1528                         return 1;
1529
1530                 entry1 = EXT4_XATTR_NEXT(entry1);
1531                 entry2 = EXT4_XATTR_NEXT(entry2);
1532         }
1533         if (!IS_LAST_ENTRY(entry2))
1534                 return 1;
1535         return 0;
1536 }
1537
1538 /*
1539  * ext4_xattr_cache_find()
1540  *
1541  * Find an identical extended attribute block.
1542  *
1543  * Returns a pointer to the block found, or NULL if such a block was
1544  * not found or an error occurred.
1545  */
1546 static struct buffer_head *
1547 ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
1548                       struct mb_cache_entry **pce)
1549 {
1550         __u32 hash = le32_to_cpu(header->h_hash);
1551         struct mb_cache_entry *ce;
1552
1553         if (!header->h_hash)
1554                 return NULL;  /* never share */
1555         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1556 again:
1557         ce = mb_cache_entry_find_first(ext4_xattr_cache, inode->i_sb->s_bdev,
1558                                        hash);
1559         while (ce) {
1560                 struct buffer_head *bh;
1561
1562                 if (IS_ERR(ce)) {
1563                         if (PTR_ERR(ce) == -EAGAIN)
1564                                 goto again;
1565                         break;
1566                 }
1567                 bh = sb_bread(inode->i_sb, ce->e_block);
1568                 if (!bh) {
1569                         EXT4_ERROR_INODE(inode, "block %lu read error",
1570                                          (unsigned long) ce->e_block);
1571                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1572                                 EXT4_XATTR_REFCOUNT_MAX) {
1573                         ea_idebug(inode, "block %lu refcount %d>=%d",
1574                                   (unsigned long) ce->e_block,
1575                                   le32_to_cpu(BHDR(bh)->h_refcount),
1576                                           EXT4_XATTR_REFCOUNT_MAX);
1577                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
1578                         *pce = ce;
1579                         return bh;
1580                 }
1581                 brelse(bh);
1582                 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);
1583         }
1584         return NULL;
1585 }
1586
1587 #define NAME_HASH_SHIFT 5
1588 #define VALUE_HASH_SHIFT 16
1589
1590 /*
1591  * ext4_xattr_hash_entry()
1592  *
1593  * Compute the hash of an extended attribute.
1594  */
1595 static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
1596                                          struct ext4_xattr_entry *entry)
1597 {
1598         __u32 hash = 0;
1599         char *name = entry->e_name;
1600         int n;
1601
1602         for (n = 0; n < entry->e_name_len; n++) {
1603                 hash = (hash << NAME_HASH_SHIFT) ^
1604                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1605                        *name++;
1606         }
1607
1608         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1609                 __le32 *value = (__le32 *)((char *)header +
1610                         le16_to_cpu(entry->e_value_offs));
1611                 for (n = (le32_to_cpu(entry->e_value_size) +
1612                      EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {
1613                         hash = (hash << VALUE_HASH_SHIFT) ^
1614                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1615                                le32_to_cpu(*value++);
1616                 }
1617         }
1618         entry->e_hash = cpu_to_le32(hash);
1619 }
1620
1621 #undef NAME_HASH_SHIFT
1622 #undef VALUE_HASH_SHIFT
1623
1624 #define BLOCK_HASH_SHIFT 16
1625
1626 /*
1627  * ext4_xattr_rehash()
1628  *
1629  * Re-compute the extended attribute hash value after an entry has changed.
1630  */
1631 static void ext4_xattr_rehash(struct ext4_xattr_header *header,
1632                               struct ext4_xattr_entry *entry)
1633 {
1634         struct ext4_xattr_entry *here;
1635         __u32 hash = 0;
1636
1637         ext4_xattr_hash_entry(header, entry);
1638         here = ENTRY(header+1);
1639         while (!IS_LAST_ENTRY(here)) {
1640                 if (!here->e_hash) {
1641                         /* Block is not shared if an entry's hash value == 0 */
1642                         hash = 0;
1643                         break;
1644                 }
1645                 hash = (hash << BLOCK_HASH_SHIFT) ^
1646                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1647                        le32_to_cpu(here->e_hash);
1648                 here = EXT4_XATTR_NEXT(here);
1649         }
1650         header->h_hash = cpu_to_le32(hash);
1651 }
1652
1653 #undef BLOCK_HASH_SHIFT
1654
1655 int __init
1656 ext4_init_xattr(void)
1657 {
1658         ext4_xattr_cache = mb_cache_create("ext4_xattr", 6);
1659         if (!ext4_xattr_cache)
1660                 return -ENOMEM;
1661         return 0;
1662 }
1663
1664 void
1665 ext4_exit_xattr(void)
1666 {
1667         if (ext4_xattr_cache)
1668                 mb_cache_destroy(ext4_xattr_cache);
1669         ext4_xattr_cache = NULL;
1670 }