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(f...)
  86 # define ea_bdebug(f...)
  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 inode *inode, char *buffer,
  96                            size_t buffer_size);
  97
  98 static struct mb_cache *ext4_xattr_cache;
  99
 100 static struct xattr_handler *ext4_xattr_handler_map[] = {
 101         [EXT4_XATTR_INDEX_USER]              = &ext4_xattr_user_handler,
 102 #ifdef CONFIG_EXT4DEV_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_EXT4DEV_FS_SECURITY
 108         [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
 109 #endif
 110 };
 111
 112 struct xattr_handler *ext4_xattr_handlers[] = {
 113         &ext4_xattr_user_handler,
 114         &ext4_xattr_trusted_handler,
 115 #ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
 116         &ext4_xattr_acl_access_handler,
 117         &ext4_xattr_acl_default_handler,
 118 #endif
 119 #ifdef CONFIG_EXT4DEV_FS_SECURITY
 120         &ext4_xattr_security_handler,
 121 #endif
 122         NULL
 123 };
 124
 125 static inline struct xattr_handler *
 126 ext4_xattr_handler(int name_index)
 127 {
 128         struct xattr_handler *handler = NULL;
 129
 130         if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
 131                 handler = ext4_xattr_handler_map[name_index];
 132         return handler;
 133 }
 134
 135 /*
 136  * Inode operation listxattr()
 137  *
 138  * dentry->d_inode->i_mutex: don't care
 139  */
 140 ssize_t
 141 ext4_listxattr(struct dentry *dentry, char *buffer, size_t size)
 142 {
 143         return ext4_xattr_list(dentry->d_inode, buffer, size);
 144 }
 145
 146 static int
 147 ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end)
 148 {
 149         while (!IS_LAST_ENTRY(entry)) {
 150                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(entry);
 151                 if ((void *)next >= end)
 152                         return -EIO;
 153                 entry = next;
 154         }
 155         return 0;
 156 }
 157
 158 static inline int
 159 ext4_xattr_check_block(struct buffer_head *bh)
 160 {
 161         int error;
 162
 163         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
 164             BHDR(bh)->h_blocks != cpu_to_le32(1))
 165                 return -EIO;
 166         error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
 167         return error;
 168 }
 169
 170 static inline int
 171 ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size)
 172 {
 173         size_t value_size = le32_to_cpu(entry->e_value_size);
 174
 175         if (entry->e_value_block != 0 || value_size > size ||
 176             le16_to_cpu(entry->e_value_offs) + value_size > size)
 177                 return -EIO;
 178         return 0;
 179 }
 180
 181 static int
 182 ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
 183                       const char *name, size_t size, int sorted)
 184 {
 185         struct ext4_xattr_entry *entry;
 186         size_t name_len;
 187         int cmp = 1;
 188
 189         if (name == NULL)
 190                 return -EINVAL;
 191         name_len = strlen(name);
 192         entry = *pentry;
 193         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 194                 cmp = name_index - entry->e_name_index;
 195                 if (!cmp)
 196                         cmp = name_len - entry->e_name_len;
 197                 if (!cmp)
 198                         cmp = memcmp(name, entry->e_name, name_len);
 199                 if (cmp <= 0 && (sorted || cmp == 0))
 200                         break;
 201         }
 202         *pentry = entry;
 203         if (!cmp && ext4_xattr_check_entry(entry, size))
 204                         return -EIO;
 205         return cmp ? -ENODATA : 0;
 206 }
 207
 208 static int
 209 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
 210                      void *buffer, size_t buffer_size)
 211 {
 212         struct buffer_head *bh = NULL;
 213         struct ext4_xattr_entry *entry;
 214         size_t size;
 215         int error;
 216
 217         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 218                   name_index, name, buffer, (long)buffer_size);
 219
 220         error = -ENODATA;
 221         if (!EXT4_I(inode)->i_file_acl)
 222                 goto cleanup;
 223         ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl);
 224         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 225         if (!bh)
 226                 goto cleanup;
 227         ea_bdebug(bh, "b_count=%d, refcount=%d",
 228                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 229         if (ext4_xattr_check_block(bh)) {
 230 bad_block:      ext4_error(inode->i_sb, __func__,
 231                            "inode %lu: bad block %llu", inode->i_ino,
 232                            EXT4_I(inode)->i_file_acl);
 233                 error = -EIO;
 234                 goto cleanup;
 235         }
 236         ext4_xattr_cache_insert(bh);
 237         entry = BFIRST(bh);
 238         error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);
 239         if (error == -EIO)
 240                 goto bad_block;
 241         if (error)
 242                 goto cleanup;
 243         size = le32_to_cpu(entry->e_value_size);
 244         if (buffer) {
 245                 error = -ERANGE;
 246                 if (size > buffer_size)
 247                         goto cleanup;
 248                 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
 249                        size);
 250         }
 251         error = size;
 252
 253 cleanup:
 254         brelse(bh);
 255         return error;
 256 }
 257
 258 static int
 259 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 260                      void *buffer, size_t buffer_size)
 261 {
 262         struct ext4_xattr_ibody_header *header;
 263         struct ext4_xattr_entry *entry;
 264         struct ext4_inode *raw_inode;
 265         struct ext4_iloc iloc;
 266         size_t size;
 267         void *end;
 268         int error;
 269
 270         if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR))
 271                 return -ENODATA;
 272         error = ext4_get_inode_loc(inode, &iloc);
 273         if (error)
 274                 return error;
 275         raw_inode = ext4_raw_inode(&iloc);
 276         header = IHDR(inode, raw_inode);
 277         entry = IFIRST(header);
 278         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 279         error = ext4_xattr_check_names(entry, end);
 280         if (error)
 281                 goto cleanup;
 282         error = ext4_xattr_find_entry(&entry, name_index, name,
 283                                       end - (void *)entry, 0);
 284         if (error)
 285                 goto cleanup;
 286         size = le32_to_cpu(entry->e_value_size);
 287         if (buffer) {
 288                 error = -ERANGE;
 289                 if (size > buffer_size)
 290                         goto cleanup;
 291                 memcpy(buffer, (void *)IFIRST(header) +
 292                        le16_to_cpu(entry->e_value_offs), size);
 293         }
 294         error = size;
 295
 296 cleanup:
 297         brelse(iloc.bh);
 298         return error;
 299 }
 300
 301 /*
 302  * ext4_xattr_get()
 303  *
 304  * Copy an extended attribute into the buffer
 305  * provided, or compute the buffer size required.
 306  * Buffer is NULL to compute the size of the buffer required.
 307  *
 308  * Returns a negative error number on failure, or the number of bytes
 309  * used / required on success.
 310  */
 311 int
 312 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
 313                void *buffer, size_t buffer_size)
 314 {
 315         int error;
 316
 317         down_read(&EXT4_I(inode)->xattr_sem);
 318         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
 319                                      buffer_size);
 320         if (error == -ENODATA)
 321                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
 322                                              buffer_size);
 323         up_read(&EXT4_I(inode)->xattr_sem);
 324         return error;
 325 }
 326
 327 static int
 328 ext4_xattr_list_entries(struct inode *inode, struct ext4_xattr_entry *entry,
 329                         char *buffer, size_t buffer_size)
 330 {
 331         size_t rest = buffer_size;
 332
 333         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 334                 struct xattr_handler *handler =
 335                         ext4_xattr_handler(entry->e_name_index);
 336
 337                 if (handler) {
 338                         size_t size = handler->list(inode, buffer, rest,
 339                                                     entry->e_name,
 340                                                     entry->e_name_len);
 341                         if (buffer) {
 342                                 if (size > rest)
 343                                         return -ERANGE;
 344                                 buffer += size;
 345                         }
 346                         rest -= size;
 347                 }
 348         }
 349         return buffer_size - rest;
 350 }
 351
 352 static int
 353 ext4_xattr_block_list(struct inode *inode, char *buffer, size_t buffer_size)
 354 {
 355         struct buffer_head *bh = NULL;
 356         int error;
 357
 358         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 359                   buffer, (long)buffer_size);
 360
 361         error = 0;
 362         if (!EXT4_I(inode)->i_file_acl)
 363                 goto cleanup;
 364         ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl);
 365         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
 366         error = -EIO;
 367         if (!bh)
 368                 goto cleanup;
 369         ea_bdebug(bh, "b_count=%d, refcount=%d",
 370                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 371         if (ext4_xattr_check_block(bh)) {
 372                 ext4_error(inode->i_sb, __func__,
 373                            "inode %lu: bad block %llu", inode->i_ino,
 374                            EXT4_I(inode)->i_file_acl);
 375                 error = -EIO;
 376                 goto cleanup;
 377         }
 378         ext4_xattr_cache_insert(bh);
 379         error = ext4_xattr_list_entries(inode, BFIRST(bh), buffer, buffer_size);
 380
 381 cleanup:
 382         brelse(bh);
 383
 384         return error;
 385 }
 386
 387 static int
 388 ext4_xattr_ibody_list(struct inode *inode, char *buffer, size_t buffer_size)
 389 {
 390         struct ext4_xattr_ibody_header *header;
 391         struct ext4_inode *raw_inode;
 392         struct ext4_iloc iloc;
 393         void *end;
 394         int error;
 395
 396         if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR))
 397                 return 0;
 398         error = ext4_get_inode_loc(inode, &iloc);
 399         if (error)
 400                 return error;
 401         raw_inode = ext4_raw_inode(&iloc);
 402         header = IHDR(inode, raw_inode);
 403         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 404         error = ext4_xattr_check_names(IFIRST(header), end);
 405         if (error)
 406                 goto cleanup;
 407         error = ext4_xattr_list_entries(inode, IFIRST(header),
 408                                         buffer, buffer_size);
 409
 410 cleanup:
 411         brelse(iloc.bh);
 412         return error;
 413 }
 414
 415 /*
 416  * ext4_xattr_list()
 417  *
 418  * Copy a list of attribute names into the buffer
 419  * provided, or compute the buffer size required.
 420  * Buffer is NULL to compute the size of the buffer required.
 421  *
 422  * Returns a negative error number on failure, or the number of bytes
 423  * used / required on success.
 424  */
 425 static int
 426 ext4_xattr_list(struct inode *inode, char *buffer, size_t buffer_size)
 427 {
 428         int i_error, b_error;
 429
 430         down_read(&EXT4_I(inode)->xattr_sem);
 431         i_error = ext4_xattr_ibody_list(inode, buffer, buffer_size);
 432         if (i_error < 0) {
 433                 b_error = 0;
 434         } else {
 435                 if (buffer) {
 436                         buffer += i_error;
 437                         buffer_size -= i_error;
 438                 }
 439                 b_error = ext4_xattr_block_list(inode, buffer, buffer_size);
 440                 if (b_error < 0)
 441                         i_error = 0;
 442         }
 443         up_read(&EXT4_I(inode)->xattr_sem);
 444         return i_error + b_error;
 445 }
 446
 447 /*
 448  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 449  * not set, set it.
 450  */
 451 static void ext4_xattr_update_super_block(handle_t *handle,
 452                                           struct super_block *sb)
 453 {
 454         if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR))
 455                 return;
 456
 457         if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
 458                 EXT4_SET_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR);
 459                 sb->s_dirt = 1;
 460                 ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh);
 461         }
 462 }
 463
 464 /*
 465  * Release the xattr block BH: If the reference count is > 1, decrement
 466  * it; otherwise free the block.
 467  */
 468 static void
 469 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
 470                          struct buffer_head *bh)
 471 {
 472         struct mb_cache_entry *ce = NULL;
 473         int error = 0;
 474
 475         ce = mb_cache_entry_get(ext4_xattr_cache, bh->b_bdev, bh->b_blocknr);
 476         error = ext4_journal_get_write_access(handle, bh);
 477         if (error)
 478                 goto out;
 479
 480         lock_buffer(bh);
 481         if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
 482                 ea_bdebug(bh, "refcount now=0; freeing");
 483                 if (ce)
 484                         mb_cache_entry_free(ce);
 485                 ext4_free_blocks(handle, inode, bh->b_blocknr, 1, 1);
 486                 get_bh(bh);
 487                 ext4_forget(handle, 1, inode, bh, bh->b_blocknr);
 488         } else {
 489                 le32_add_cpu(&BHDR(bh)->h_refcount, -1);
 490                 error = ext4_journal_dirty_metadata(handle, bh);
 491                 if (IS_SYNC(inode))
 492                         handle->h_sync = 1;
 493                 DQUOT_FREE_BLOCK(inode, 1);
 494                 ea_bdebug(bh, "refcount now=%d; releasing",
 495                           le32_to_cpu(BHDR(bh)->h_refcount));
 496                 if (ce)
 497                         mb_cache_entry_release(ce);
 498         }
 499         unlock_buffer(bh);
 500 out:
 501         ext4_std_error(inode->i_sb, error);
 502         return;
 503 }
 504
 505 /*
 506  * Find the available free space for EAs. This also returns the total number of
 507  * bytes used by EA entries.
 508  */
 509 static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
 510                                     size_t *min_offs, void *base, int *total)
 511 {
 512         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 513                 *total += EXT4_XATTR_LEN(last->e_name_len);
 514                 if (!last->e_value_block && last->e_value_size) {
 515                         size_t offs = le16_to_cpu(last->e_value_offs);
 516                         if (offs < *min_offs)
 517                                 *min_offs = offs;
 518                 }
 519         }
 520         return (*min_offs - ((void *)last - base) - sizeof(__u32));
 521 }
 522
 523 struct ext4_xattr_info {
 524         int name_index;
 525         const char *name;
 526         const void *value;
 527         size_t value_len;
 528 };
 529
 530 struct ext4_xattr_search {
 531         struct ext4_xattr_entry *first;
 532         void *base;
 533         void *end;
 534         struct ext4_xattr_entry *here;
 535         int not_found;
 536 };
 537
 538 static int
 539 ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)
 540 {
 541         struct ext4_xattr_entry *last;
 542         size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
 543
 544         /* Compute min_offs and last. */
 545         last = s->first;
 546         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
 547                 if (!last->e_value_block && last->e_value_size) {
 548                         size_t offs = le16_to_cpu(last->e_value_offs);
 549                         if (offs < min_offs)
 550                                 min_offs = offs;
 551                 }
 552         }
 553         free = min_offs - ((void *)last - s->base) - sizeof(__u32);
 554         if (!s->not_found) {
 555                 if (!s->here->e_value_block && s->here->e_value_size) {
 556                         size_t size = le32_to_cpu(s->here->e_value_size);
 557                         free += EXT4_XATTR_SIZE(size);
 558                 }
 559                 free += EXT4_XATTR_LEN(name_len);
 560         }
 561         if (i->value) {
 562                 if (free < EXT4_XATTR_SIZE(i->value_len) ||
 563                     free < EXT4_XATTR_LEN(name_len) +
 564                            EXT4_XATTR_SIZE(i->value_len))
 565                         return -ENOSPC;
 566         }
 567
 568         if (i->value && s->not_found) {
 569                 /* Insert the new name. */
 570                 size_t size = EXT4_XATTR_LEN(name_len);
 571                 size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
 572                 memmove((void *)s->here + size, s->here, rest);
 573                 memset(s->here, 0, size);
 574                 s->here->e_name_index = i->name_index;
 575                 s->here->e_name_len = name_len;
 576                 memcpy(s->here->e_name, i->name, name_len);
 577         } else {
 578                 if (!s->here->e_value_block && s->here->e_value_size) {
 579                         void *first_val = s->base + min_offs;
 580                         size_t offs = le16_to_cpu(s->here->e_value_offs);
 581                         void *val = s->base + offs;
 582                         size_t size = EXT4_XATTR_SIZE(
 583                                 le32_to_cpu(s->here->e_value_size));
 584
 585                         if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {
 586                                 /* The old and the new value have the same
 587                                    size. Just replace. */
 588                                 s->here->e_value_size =
 589                                         cpu_to_le32(i->value_len);
 590                                 memset(val + size - EXT4_XATTR_PAD, 0,
 591                                        EXT4_XATTR_PAD); /* Clear pad bytes. */
 592                                 memcpy(val, i->value, i->value_len);
 593                                 return 0;
 594                         }
 595
 596                         /* Remove the old value. */
 597                         memmove(first_val + size, first_val, val - first_val);
 598                         memset(first_val, 0, size);
 599                         s->here->e_value_size = 0;
 600                         s->here->e_value_offs = 0;
 601                         min_offs += size;
 602
 603                         /* Adjust all value offsets. */
 604                         last = s->first;
 605                         while (!IS_LAST_ENTRY(last)) {
 606                                 size_t o = le16_to_cpu(last->e_value_offs);
 607                                 if (!last->e_value_block &&
 608                                     last->e_value_size && o < offs)
 609                                         last->e_value_offs =
 610                                                 cpu_to_le16(o + size);
 611                                 last = EXT4_XATTR_NEXT(last);
 612                         }
 613                 }
 614                 if (!i->value) {
 615                         /* Remove the old name. */
 616                         size_t size = EXT4_XATTR_LEN(name_len);
 617                         last = ENTRY((void *)last - size);
 618                         memmove(s->here, (void *)s->here + size,
 619                                 (void *)last - (void *)s->here + sizeof(__u32));
 620                         memset(last, 0, size);
 621                 }
 622         }
 623
 624         if (i->value) {
 625                 /* Insert the new value. */
 626                 s->here->e_value_size = cpu_to_le32(i->value_len);
 627                 if (i->value_len) {
 628                         size_t size = EXT4_XATTR_SIZE(i->value_len);
 629                         void *val = s->base + min_offs - size;
 630                         s->here->e_value_offs = cpu_to_le16(min_offs - size);
 631                         memset(val + size - EXT4_XATTR_PAD, 0,
 632                                EXT4_XATTR_PAD); /* Clear the pad bytes. */
 633                         memcpy(val, i->value, i->value_len);
 634                 }
 635         }
 636         return 0;
 637 }
 638
 639 struct ext4_xattr_block_find {
 640         struct ext4_xattr_search s;
 641         struct buffer_head *bh;
 642 };
 643
 644 static int
 645 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
 646                       struct ext4_xattr_block_find *bs)
 647 {
 648         struct super_block *sb = inode->i_sb;
 649         int error;
 650
 651         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
 652                   i->name_index, i->name, i->value, (long)i->value_len);
 653
 654         if (EXT4_I(inode)->i_file_acl) {
 655                 /* The inode already has an extended attribute block. */
 656                 bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);
 657                 error = -EIO;
 658                 if (!bs->bh)
 659                         goto cleanup;
 660                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
 661                         atomic_read(&(bs->bh->b_count)),
 662                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
 663                 if (ext4_xattr_check_block(bs->bh)) {
 664                         ext4_error(sb, __func__,
 665                                 "inode %lu: bad block %llu", inode->i_ino,
 666                                 EXT4_I(inode)->i_file_acl);
 667                         error = -EIO;
 668                         goto cleanup;
 669                 }
 670                 /* Find the named attribute. */
 671                 bs->s.base = BHDR(bs->bh);
 672                 bs->s.first = BFIRST(bs->bh);
 673                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
 674                 bs->s.here = bs->s.first;
 675                 error = ext4_xattr_find_entry(&bs->s.here, i->name_index,
 676                                               i->name, bs->bh->b_size, 1);
 677                 if (error && error != -ENODATA)
 678                         goto cleanup;
 679                 bs->s.not_found = error;
 680         }
 681         error = 0;
 682
 683 cleanup:
 684         return error;
 685 }
 686
 687 static int
 688 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
 689                      struct ext4_xattr_info *i,
 690                      struct ext4_xattr_block_find *bs)
 691 {
 692         struct super_block *sb = inode->i_sb;
 693         struct buffer_head *new_bh = NULL;
 694         struct ext4_xattr_search *s = &bs->s;
 695         struct mb_cache_entry *ce = NULL;
 696         int error = 0;
 697
 698 #define header(x) ((struct ext4_xattr_header *)(x))
 699
 700         if (i->value && i->value_len > sb->s_blocksize)
 701                 return -ENOSPC;
 702         if (s->base) {
 703                 ce = mb_cache_entry_get(ext4_xattr_cache, bs->bh->b_bdev,
 704                                         bs->bh->b_blocknr);
 705                 error = ext4_journal_get_write_access(handle, bs->bh);
 706                 if (error)
 707                         goto cleanup;
 708                 lock_buffer(bs->bh);
 709
 710                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
 711                         if (ce) {
 712                                 mb_cache_entry_free(ce);
 713                                 ce = NULL;
 714                         }
 715                         ea_bdebug(bs->bh, "modifying in-place");
 716                         error = ext4_xattr_set_entry(i, s);
 717                         if (!error) {
 718                                 if (!IS_LAST_ENTRY(s->first))
 719                                         ext4_xattr_rehash(header(s->base),
 720                                                           s->here);
 721                                 ext4_xattr_cache_insert(bs->bh);
 722                         }
 723                         unlock_buffer(bs->bh);
 724                         if (error == -EIO)
 725                                 goto bad_block;
 726                         if (!error)
 727                                 error = ext4_journal_dirty_metadata(handle,
 728                                                                     bs->bh);
 729                         if (error)
 730                                 goto cleanup;
 731                         goto inserted;
 732                 } else {
 733                         int offset = (char *)s->here - bs->bh->b_data;
 734
 735                         unlock_buffer(bs->bh);
 736                         jbd2_journal_release_buffer(handle, bs->bh);
 737                         if (ce) {
 738                                 mb_cache_entry_release(ce);
 739                                 ce = NULL;
 740                         }
 741                         ea_bdebug(bs->bh, "cloning");
 742                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
 743                         error = -ENOMEM;
 744                         if (s->base == NULL)
 745                                 goto cleanup;
 746                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
 747                         s->first = ENTRY(header(s->base)+1);
 748                         header(s->base)->h_refcount = cpu_to_le32(1);
 749                         s->here = ENTRY(s->base + offset);
 750                         s->end = s->base + bs->bh->b_size;
 751                 }
 752         } else {
 753                 /* Allocate a buffer where we construct the new block. */
 754                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
 755                 /* assert(header == s->base) */
 756                 error = -ENOMEM;
 757                 if (s->base == NULL)
 758                         goto cleanup;
 759                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
 760                 header(s->base)->h_blocks = cpu_to_le32(1);
 761                 header(s->base)->h_refcount = cpu_to_le32(1);
 762                 s->first = ENTRY(header(s->base)+1);
 763                 s->here = ENTRY(header(s->base)+1);
 764                 s->end = s->base + sb->s_blocksize;
 765         }
 766
 767         error = ext4_xattr_set_entry(i, s);
 768         if (error == -EIO)
 769                 goto bad_block;
 770         if (error)
 771                 goto cleanup;
 772         if (!IS_LAST_ENTRY(s->first))
 773                 ext4_xattr_rehash(header(s->base), s->here);
 774
 775 inserted:
 776         if (!IS_LAST_ENTRY(s->first)) {
 777                 new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);
 778                 if (new_bh) {
 779                         /* We found an identical block in the cache. */
 780                         if (new_bh == bs->bh)
 781                                 ea_bdebug(new_bh, "keeping");
 782                         else {
 783                                 /* The old block is released after updating
 784                                    the inode. */
 785                                 error = -EDQUOT;
 786                                 if (DQUOT_ALLOC_BLOCK(inode, 1))
 787                                         goto cleanup;
 788                                 error = ext4_journal_get_write_access(handle,
 789                                                                       new_bh);
 790                                 if (error)
 791                                         goto cleanup_dquot;
 792                                 lock_buffer(new_bh);
 793                                 le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);
 794                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
 795                                         le32_to_cpu(BHDR(new_bh)->h_refcount));
 796                                 unlock_buffer(new_bh);
 797                                 error = ext4_journal_dirty_metadata(handle,
 798                                                                     new_bh);
 799                                 if (error)
 800                                         goto cleanup_dquot;
 801                         }
 802                         mb_cache_entry_release(ce);
 803                         ce = NULL;
 804                 } else if (bs->bh && s->base == bs->bh->b_data) {
 805                         /* We were modifying this block in-place. */
 806                         ea_bdebug(bs->bh, "keeping this block");
 807                         new_bh = bs->bh;
 808                         get_bh(new_bh);
 809                 } else {
 810                         /* We need to allocate a new block */
 811                         ext4_fsblk_t goal = ext4_group_first_block_no(sb,
 812                                                 EXT4_I(inode)->i_block_group);
 813                         ext4_fsblk_t block = ext4_new_meta_block(handle, inode,
 814                                                         goal, &error);
 815                         if (error)
 816                                 goto cleanup;
 817                         ea_idebug(inode, "creating block %d", block);
 818
 819                         new_bh = sb_getblk(sb, block);
 820                         if (!new_bh) {
 821 getblk_failed:
 822                                 ext4_free_blocks(handle, inode, block, 1, 1);
 823                                 error = -EIO;
 824                                 goto cleanup;
 825                         }
 826                         lock_buffer(new_bh);
 827                         error = ext4_journal_get_create_access(handle, new_bh);
 828                         if (error) {
 829                                 unlock_buffer(new_bh);
 830                                 goto getblk_failed;
 831                         }
 832                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
 833                         set_buffer_uptodate(new_bh);
 834                         unlock_buffer(new_bh);
 835                         ext4_xattr_cache_insert(new_bh);
 836                         error = ext4_journal_dirty_metadata(handle, new_bh);
 837                         if (error)
 838                                 goto cleanup;
 839                 }
 840         }
 841
 842         /* Update the inode. */
 843         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
 844
 845         /* Drop the previous xattr block. */
 846         if (bs->bh && bs->bh != new_bh)
 847                 ext4_xattr_release_block(handle, inode, bs->bh);
 848         error = 0;
 849
 850 cleanup:
 851         if (ce)
 852                 mb_cache_entry_release(ce);
 853         brelse(new_bh);
 854         if (!(bs->bh && s->base == bs->bh->b_data))
 855                 kfree(s->base);
 856
 857         return error;
 858
 859 cleanup_dquot:
 860         DQUOT_FREE_BLOCK(inode, 1);
 861         goto cleanup;
 862
 863 bad_block:
 864         ext4_error(inode->i_sb, __func__,
 865                    "inode %lu: bad block %llu", inode->i_ino,
 866                    EXT4_I(inode)->i_file_acl);
 867         goto cleanup;
 868
 869 #undef header
 870 }
 871
 872 struct ext4_xattr_ibody_find {
 873         struct ext4_xattr_search s;
 874         struct ext4_iloc iloc;
 875 };
 876
 877 static int
 878 ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
 879                       struct ext4_xattr_ibody_find *is)
 880 {
 881         struct ext4_xattr_ibody_header *header;
 882         struct ext4_inode *raw_inode;
 883         int error;
 884
 885         if (EXT4_I(inode)->i_extra_isize == 0)
 886                 return 0;
 887         raw_inode = ext4_raw_inode(&is->iloc);
 888         header = IHDR(inode, raw_inode);
 889         is->s.base = is->s.first = IFIRST(header);
 890         is->s.here = is->s.first;
 891         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 892         if (EXT4_I(inode)->i_state & EXT4_STATE_XATTR) {
 893                 error = ext4_xattr_check_names(IFIRST(header), is->s.end);
 894                 if (error)
 895                         return error;
 896                 /* Find the named attribute. */
 897                 error = ext4_xattr_find_entry(&is->s.here, i->name_index,
 898                                               i->name, is->s.end -
 899                                               (void *)is->s.base, 0);
 900                 if (error && error != -ENODATA)
 901                         return error;
 902                 is->s.not_found = error;
 903         }
 904         return 0;
 905 }
 906
 907 static int
 908 ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
 909                      struct ext4_xattr_info *i,
 910                      struct ext4_xattr_ibody_find *is)
 911 {
 912         struct ext4_xattr_ibody_header *header;
 913         struct ext4_xattr_search *s = &is->s;
 914         int error;
 915
 916         if (EXT4_I(inode)->i_extra_isize == 0)
 917                 return -ENOSPC;
 918         error = ext4_xattr_set_entry(i, s);
 919         if (error)
 920                 return error;
 921         header = IHDR(inode, ext4_raw_inode(&is->iloc));
 922         if (!IS_LAST_ENTRY(s->first)) {
 923                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
 924                 EXT4_I(inode)->i_state |= EXT4_STATE_XATTR;
 925         } else {
 926                 header->h_magic = cpu_to_le32(0);
 927                 EXT4_I(inode)->i_state &= ~EXT4_STATE_XATTR;
 928         }
 929         return 0;
 930 }
 931
 932 /*
 933  * ext4_xattr_set_handle()
 934  *
 935  * Create, replace or remove an extended attribute for this inode. Buffer
 936  * is NULL to remove an existing extended attribute, and non-NULL to
 937  * either replace an existing extended attribute, or create a new extended
 938  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 939  * specify that an extended attribute must exist and must not exist
 940  * previous to the call, respectively.
 941  *
 942  * Returns 0, or a negative error number on failure.
 943  */
 944 int
 945 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
 946                       const char *name, const void *value, size_t value_len,
 947                       int flags)
 948 {
 949         struct ext4_xattr_info i = {
 950                 .name_index = name_index,
 951                 .name = name,
 952                 .value = value,
 953                 .value_len = value_len,
 954
 955         };
 956         struct ext4_xattr_ibody_find is = {
 957                 .s = { .not_found = -ENODATA, },
 958         };
 959         struct ext4_xattr_block_find bs = {
 960                 .s = { .not_found = -ENODATA, },
 961         };
 962         int error;
 963
 964         if (!name)
 965                 return -EINVAL;
 966         if (strlen(name) > 255)
 967                 return -ERANGE;
 968         down_write(&EXT4_I(inode)->xattr_sem);
 969         error = ext4_get_inode_loc(inode, &is.iloc);
 970         if (error)
 971                 goto cleanup;
 972
 973         if (EXT4_I(inode)->i_state & EXT4_STATE_NEW) {
 974                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
 975                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
 976                 EXT4_I(inode)->i_state &= ~EXT4_STATE_NEW;
 977         }
 978
 979         error = ext4_xattr_ibody_find(inode, &i, &is);
 980         if (error)
 981                 goto cleanup;
 982         if (is.s.not_found)
 983                 error = ext4_xattr_block_find(inode, &i, &bs);
 984         if (error)
 985                 goto cleanup;
 986         if (is.s.not_found && bs.s.not_found) {
 987                 error = -ENODATA;
 988                 if (flags & XATTR_REPLACE)
 989                         goto cleanup;
 990                 error = 0;
 991                 if (!value)
 992                         goto cleanup;
 993         } else {
 994                 error = -EEXIST;
 995                 if (flags & XATTR_CREATE)
 996                         goto cleanup;
 997         }
 998         error = ext4_journal_get_write_access(handle, is.iloc.bh);
 999         if (error)
1000                 goto cleanup;
1001         if (!value) {
1002                 if (!is.s.not_found)
1003                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1004                 else if (!bs.s.not_found)
1005                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1006         } else {
1007                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
1008                 if (!error && !bs.s.not_found) {
1009                         i.value = NULL;
1010                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1011                 } else if (error == -ENOSPC) {
1012                         if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
1013                                 error = ext4_xattr_block_find(inode, &i, &bs);
1014                                 if (error)
1015                                         goto cleanup;
1016                         }
1017                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
1018                         if (error)
1019                                 goto cleanup;
1020                         if (!is.s.not_found) {
1021                                 i.value = NULL;
1022                                 error = ext4_xattr_ibody_set(handle, inode, &i,
1023                                                              &is);
1024                         }
1025                 }
1026         }
1027         if (!error) {
1028                 ext4_xattr_update_super_block(handle, inode->i_sb);
1029                 inode->i_ctime = ext4_current_time(inode);
1030                 if (!value)
1031                         EXT4_I(inode)->i_state &= ~EXT4_STATE_NO_EXPAND;
1032                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
1033                 /*
1034                  * The bh is consumed by ext4_mark_iloc_dirty, even with
1035                  * error != 0.
1036                  */
1037                 is.iloc.bh = NULL;
1038                 if (IS_SYNC(inode))
1039                         handle->h_sync = 1;
1040         }
1041
1042 cleanup:
1043         brelse(is.iloc.bh);
1044         brelse(bs.bh);
1045         up_write(&EXT4_I(inode)->xattr_sem);
1046         return error;
1047 }
1048
1049 /*
1050  * ext4_xattr_set()
1051  *
1052  * Like ext4_xattr_set_handle, but start from an inode. This extended
1053  * attribute modification is a filesystem transaction by itself.
1054  *
1055  * Returns 0, or a negative error number on failure.
1056  */
1057 int
1058 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
1059                const void *value, size_t value_len, int flags)
1060 {
1061         handle_t *handle;
1062         int error, retries = 0;
1063
1064 retry:
1065         handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
1066         if (IS_ERR(handle)) {
1067                 error = PTR_ERR(handle);
1068         } else {
1069                 int error2;
1070
1071                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
1072                                               value, value_len, flags);
1073                 error2 = ext4_journal_stop(handle);
1074                 if (error == -ENOSPC &&
1075                     ext4_should_retry_alloc(inode->i_sb, &retries))
1076                         goto retry;
1077                 if (error == 0)
1078                         error = error2;
1079         }
1080
1081         return error;
1082 }
1083
1084 /*
1085  * Shift the EA entries in the inode to create space for the increased
1086  * i_extra_isize.
1087  */
1088 static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
1089                                      int value_offs_shift, void *to,
1090                                      void *from, size_t n, int blocksize)
1091 {
1092         struct ext4_xattr_entry *last = entry;
1093         int new_offs;
1094
1095         /* Adjust the value offsets of the entries */
1096         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1097                 if (!last->e_value_block && last->e_value_size) {
1098                         new_offs = le16_to_cpu(last->e_value_offs) +
1099                                                         value_offs_shift;
1100                         BUG_ON(new_offs + le32_to_cpu(last->e_value_size)
1101                                  > blocksize);
1102                         last->e_value_offs = cpu_to_le16(new_offs);
1103                 }
1104         }
1105         /* Shift the entries by n bytes */
1106         memmove(to, from, n);
1107 }
1108
1109 /*
1110  * Expand an inode by new_extra_isize bytes when EAs are present.
1111  * Returns 0 on success or negative error number on failure.
1112  */
1113 int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
1114                                struct ext4_inode *raw_inode, handle_t *handle)
1115 {
1116         struct ext4_xattr_ibody_header *header;
1117         struct ext4_xattr_entry *entry, *last, *first;
1118         struct buffer_head *bh = NULL;
1119         struct ext4_xattr_ibody_find *is = NULL;
1120         struct ext4_xattr_block_find *bs = NULL;
1121         char *buffer = NULL, *b_entry_name = NULL;
1122         size_t min_offs, free;
1123         int total_ino, total_blk;
1124         void *base, *start, *end;
1125         int extra_isize = 0, error = 0, tried_min_extra_isize = 0;
1126         int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize);
1127
1128         down_write(&EXT4_I(inode)->xattr_sem);
1129 retry:
1130         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize) {
1131                 up_write(&EXT4_I(inode)->xattr_sem);
1132                 return 0;
1133         }
1134
1135         header = IHDR(inode, raw_inode);
1136         entry = IFIRST(header);
1137
1138         /*
1139          * Check if enough free space is available in the inode to shift the
1140          * entries ahead by new_extra_isize.
1141          */
1142
1143         base = start = entry;
1144         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
1145         min_offs = end - base;
1146         last = entry;
1147         total_ino = sizeof(struct ext4_xattr_ibody_header);
1148
1149         free = ext4_xattr_free_space(last, &min_offs, base, &total_ino);
1150         if (free >= new_extra_isize) {
1151                 entry = IFIRST(header);
1152                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize
1153                                 - new_extra_isize, (void *)raw_inode +
1154                                 EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
1155                                 (void *)header, total_ino,
1156                                 inode->i_sb->s_blocksize);
1157                 EXT4_I(inode)->i_extra_isize = new_extra_isize;
1158                 error = 0;
1159                 goto cleanup;
1160         }
1161
1162         /*
1163          * Enough free space isn't available in the inode, check if
1164          * EA block can hold new_extra_isize bytes.
1165          */
1166         if (EXT4_I(inode)->i_file_acl) {
1167                 bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1168                 error = -EIO;
1169                 if (!bh)
1170                         goto cleanup;
1171                 if (ext4_xattr_check_block(bh)) {
1172                         ext4_error(inode->i_sb, __func__,
1173                                 "inode %lu: bad block %llu", inode->i_ino,
1174                                 EXT4_I(inode)->i_file_acl);
1175                         error = -EIO;
1176                         goto cleanup;
1177                 }
1178                 base = BHDR(bh);
1179                 first = BFIRST(bh);
1180                 end = bh->b_data + bh->b_size;
1181                 min_offs = end - base;
1182                 free = ext4_xattr_free_space(first, &min_offs, base,
1183                                              &total_blk);
1184                 if (free < new_extra_isize) {
1185                         if (!tried_min_extra_isize && s_min_extra_isize) {
1186                                 tried_min_extra_isize++;
1187                                 new_extra_isize = s_min_extra_isize;
1188                                 brelse(bh);
1189                                 goto retry;
1190                         }
1191                         error = -1;
1192                         goto cleanup;
1193                 }
1194         } else {
1195                 free = inode->i_sb->s_blocksize;
1196         }
1197
1198         while (new_extra_isize > 0) {
1199                 size_t offs, size, entry_size;
1200                 struct ext4_xattr_entry *small_entry = NULL;
1201                 struct ext4_xattr_info i = {
1202                         .value = NULL,
1203                         .value_len = 0,
1204                 };
1205                 unsigned int total_size;  /* EA entry size + value size */
1206                 unsigned int shift_bytes; /* No. of bytes to shift EAs by? */
1207                 unsigned int min_total_size = ~0U;
1208
1209                 is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
1210                 bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
1211                 if (!is || !bs) {
1212                         error = -ENOMEM;
1213                         goto cleanup;
1214                 }
1215
1216                 is->s.not_found = -ENODATA;
1217                 bs->s.not_found = -ENODATA;
1218                 is->iloc.bh = NULL;
1219                 bs->bh = NULL;
1220
1221                 last = IFIRST(header);
1222                 /* Find the entry best suited to be pushed into EA block */
1223                 entry = NULL;
1224                 for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1225                         total_size =
1226                         EXT4_XATTR_SIZE(le32_to_cpu(last->e_value_size)) +
1227                                         EXT4_XATTR_LEN(last->e_name_len);
1228                         if (total_size <= free && total_size < min_total_size) {
1229                                 if (total_size < new_extra_isize) {
1230                                         small_entry = last;
1231                                 } else {
1232                                         entry = last;
1233                                         min_total_size = total_size;
1234                                 }
1235                         }
1236                 }
1237
1238                 if (entry == NULL) {
1239                         if (small_entry) {
1240                                 entry = small_entry;
1241                         } else {
1242                                 if (!tried_min_extra_isize &&
1243                                     s_min_extra_isize) {
1244                                         tried_min_extra_isize++;
1245                                         new_extra_isize = s_min_extra_isize;
1246                                         goto retry;
1247                                 }
1248                                 error = -1;
1249                                 goto cleanup;
1250                         }
1251                 }
1252                 offs = le16_to_cpu(entry->e_value_offs);
1253                 size = le32_to_cpu(entry->e_value_size);
1254                 entry_size = EXT4_XATTR_LEN(entry->e_name_len);
1255                 i.name_index = entry->e_name_index,
1256                 buffer = kmalloc(EXT4_XATTR_SIZE(size), GFP_NOFS);
1257                 b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
1258                 if (!buffer || !b_entry_name) {
1259                         error = -ENOMEM;
1260                         goto cleanup;
1261                 }
1262                 /* Save the entry name and the entry value */
1263                 memcpy(buffer, (void *)IFIRST(header) + offs,
1264                        EXT4_XATTR_SIZE(size));
1265                 memcpy(b_entry_name, entry->e_name, entry->e_name_len);
1266                 b_entry_name[entry->e_name_len] = '\0';
1267                 i.name = b_entry_name;
1268
1269                 error = ext4_get_inode_loc(inode, &is->iloc);
1270                 if (error)
1271                         goto cleanup;
1272
1273                 error = ext4_xattr_ibody_find(inode, &i, is);
1274                 if (error)
1275                         goto cleanup;
1276
1277                 /* Remove the chosen entry from the inode */
1278                 error = ext4_xattr_ibody_set(handle, inode, &i, is);
1279
1280                 entry = IFIRST(header);
1281                 if (entry_size + EXT4_XATTR_SIZE(size) >= new_extra_isize)
1282                         shift_bytes = new_extra_isize;
1283                 else
1284                         shift_bytes = entry_size + size;
1285                 /* Adjust the offsets and shift the remaining entries ahead */
1286                 ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize -
1287                         shift_bytes, (void *)raw_inode +
1288                         EXT4_GOOD_OLD_INODE_SIZE + extra_isize + shift_bytes,
1289                         (void *)header, total_ino - entry_size,
1290                         inode->i_sb->s_blocksize);
1291
1292                 extra_isize += shift_bytes;
1293                 new_extra_isize -= shift_bytes;
1294                 EXT4_I(inode)->i_extra_isize = extra_isize;
1295
1296                 i.name = b_entry_name;
1297                 i.value = buffer;
1298                 i.value_len = size;
1299                 error = ext4_xattr_block_find(inode, &i, bs);
1300                 if (error)
1301                         goto cleanup;
1302
1303                 /* Add entry which was removed from the inode into the block */
1304                 error = ext4_xattr_block_set(handle, inode, &i, bs);
1305                 if (error)
1306                         goto cleanup;
1307                 kfree(b_entry_name);
1308                 kfree(buffer);
1309                 brelse(is->iloc.bh);
1310                 kfree(is);
1311                 kfree(bs);
1312         }
1313         brelse(bh);
1314         up_write(&EXT4_I(inode)->xattr_sem);
1315         return 0;
1316
1317 cleanup:
1318         kfree(b_entry_name);
1319         kfree(buffer);
1320         if (is)
1321                 brelse(is->iloc.bh);
1322         kfree(is);
1323         kfree(bs);
1324         brelse(bh);
1325         up_write(&EXT4_I(inode)->xattr_sem);
1326         return error;
1327 }
1328
1329
1330
1331 /*
1332  * ext4_xattr_delete_inode()
1333  *
1334  * Free extended attribute resources associated with this inode. This
1335  * is called immediately before an inode is freed. We have exclusive
1336  * access to the inode.
1337  */
1338 void
1339 ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)
1340 {
1341         struct buffer_head *bh = NULL;
1342
1343         if (!EXT4_I(inode)->i_file_acl)
1344                 goto cleanup;
1345         bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
1346         if (!bh) {
1347                 ext4_error(inode->i_sb, __func__,
1348                         "inode %lu: block %llu read error", inode->i_ino,
1349                         EXT4_I(inode)->i_file_acl);
1350                 goto cleanup;
1351         }
1352         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
1353             BHDR(bh)->h_blocks != cpu_to_le32(1)) {
1354                 ext4_error(inode->i_sb, __func__,
1355                         "inode %lu: bad block %llu", inode->i_ino,
1356                         EXT4_I(inode)->i_file_acl);
1357                 goto cleanup;
1358         }
1359         ext4_xattr_release_block(handle, inode, bh);
1360         EXT4_I(inode)->i_file_acl = 0;
1361
1362 cleanup:
1363         brelse(bh);
1364 }
1365
1366 /*
1367  * ext4_xattr_put_super()
1368  *
1369  * This is called when a file system is unmounted.
1370  */
1371 void
1372 ext4_xattr_put_super(struct super_block *sb)
1373 {
1374         mb_cache_shrink(sb->s_bdev);
1375 }
1376
1377 /*
1378  * ext4_xattr_cache_insert()
1379  *
1380  * Create a new entry in the extended attribute cache, and insert
1381  * it unless such an entry is already in the cache.
1382  *
1383  * Returns 0, or a negative error number on failure.
1384  */
1385 static void
1386 ext4_xattr_cache_insert(struct buffer_head *bh)
1387 {
1388         __u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
1389         struct mb_cache_entry *ce;
1390         int error;
1391
1392         ce = mb_cache_entry_alloc(ext4_xattr_cache, GFP_NOFS);
1393         if (!ce) {
1394                 ea_bdebug(bh, "out of memory");
1395                 return;
1396         }
1397         error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash);
1398         if (error) {
1399                 mb_cache_entry_free(ce);
1400                 if (error == -EBUSY) {
1401                         ea_bdebug(bh, "already in cache");
1402                         error = 0;
1403                 }
1404         } else {
1405                 ea_bdebug(bh, "inserting [%x]", (int)hash);
1406                 mb_cache_entry_release(ce);
1407         }
1408 }
1409
1410 /*
1411  * ext4_xattr_cmp()
1412  *
1413  * Compare two extended attribute blocks for equality.
1414  *
1415  * Returns 0 if the blocks are equal, 1 if they differ, and
1416  * a negative error number on errors.
1417  */
1418 static int
1419 ext4_xattr_cmp(struct ext4_xattr_header *header1,
1420                struct ext4_xattr_header *header2)
1421 {
1422         struct ext4_xattr_entry *entry1, *entry2;
1423
1424         entry1 = ENTRY(header1+1);
1425         entry2 = ENTRY(header2+1);
1426         while (!IS_LAST_ENTRY(entry1)) {
1427                 if (IS_LAST_ENTRY(entry2))
1428                         return 1;
1429                 if (entry1->e_hash != entry2->e_hash ||
1430                     entry1->e_name_index != entry2->e_name_index ||
1431                     entry1->e_name_len != entry2->e_name_len ||
1432                     entry1->e_value_size != entry2->e_value_size ||
1433                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
1434                         return 1;
1435                 if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
1436                         return -EIO;
1437                 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
1438                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
1439                            le32_to_cpu(entry1->e_value_size)))
1440                         return 1;
1441
1442                 entry1 = EXT4_XATTR_NEXT(entry1);
1443                 entry2 = EXT4_XATTR_NEXT(entry2);
1444         }
1445         if (!IS_LAST_ENTRY(entry2))
1446                 return 1;
1447         return 0;
1448 }
1449
1450 /*
1451  * ext4_xattr_cache_find()
1452  *
1453  * Find an identical extended attribute block.
1454  *
1455  * Returns a pointer to the block found, or NULL if such a block was
1456  * not found or an error occurred.
1457  */
1458 static struct buffer_head *
1459 ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
1460                       struct mb_cache_entry **pce)
1461 {
1462         __u32 hash = le32_to_cpu(header->h_hash);
1463         struct mb_cache_entry *ce;
1464
1465         if (!header->h_hash)
1466                 return NULL;  /* never share */
1467         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
1468 again:
1469         ce = mb_cache_entry_find_first(ext4_xattr_cache, 0,
1470                                        inode->i_sb->s_bdev, hash);
1471         while (ce) {
1472                 struct buffer_head *bh;
1473
1474                 if (IS_ERR(ce)) {
1475                         if (PTR_ERR(ce) == -EAGAIN)
1476                                 goto again;
1477                         break;
1478                 }
1479                 bh = sb_bread(inode->i_sb, ce->e_block);
1480                 if (!bh) {
1481                         ext4_error(inode->i_sb, __func__,
1482                                 "inode %lu: block %lu read error",
1483                                 inode->i_ino, (unsigned long) ce->e_block);
1484                 } else if (le32_to_cpu(BHDR(bh)->h_refcount) >=
1485                                 EXT4_XATTR_REFCOUNT_MAX) {
1486                         ea_idebug(inode, "block %lu refcount %d>=%d",
1487                                   (unsigned long) ce->e_block,
1488                                   le32_to_cpu(BHDR(bh)->h_refcount),
1489                                           EXT4_XATTR_REFCOUNT_MAX);
1490                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
1491                         *pce = ce;
1492                         return bh;
1493                 }
1494                 brelse(bh);
1495                 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash);
1496         }
1497         return NULL;
1498 }
1499
1500 #define NAME_HASH_SHIFT 5
1501 #define VALUE_HASH_SHIFT 16
1502
1503 /*
1504  * ext4_xattr_hash_entry()
1505  *
1506  * Compute the hash of an extended attribute.
1507  */
1508 static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
1509                                          struct ext4_xattr_entry *entry)
1510 {
1511         __u32 hash = 0;
1512         char *name = entry->e_name;
1513         int n;
1514
1515         for (n=0; n < entry->e_name_len; n++) {
1516                 hash = (hash << NAME_HASH_SHIFT) ^
1517                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
1518                        *name++;
1519         }
1520
1521         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
1522                 __le32 *value = (__le32 *)((char *)header +
1523                         le16_to_cpu(entry->e_value_offs));
1524                 for (n = (le32_to_cpu(entry->e_value_size) +
1525                      EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {
1526                         hash = (hash << VALUE_HASH_SHIFT) ^
1527                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
1528                                le32_to_cpu(*value++);
1529                 }
1530         }
1531         entry->e_hash = cpu_to_le32(hash);
1532 }
1533
1534 #undef NAME_HASH_SHIFT
1535 #undef VALUE_HASH_SHIFT
1536
1537 #define BLOCK_HASH_SHIFT 16
1538
1539 /*
1540  * ext4_xattr_rehash()
1541  *
1542  * Re-compute the extended attribute hash value after an entry has changed.
1543  */
1544 static void ext4_xattr_rehash(struct ext4_xattr_header *header,
1545                               struct ext4_xattr_entry *entry)
1546 {
1547         struct ext4_xattr_entry *here;
1548         __u32 hash = 0;
1549
1550         ext4_xattr_hash_entry(header, entry);
1551         here = ENTRY(header+1);
1552         while (!IS_LAST_ENTRY(here)) {
1553                 if (!here->e_hash) {
1554                         /* Block is not shared if an entry's hash value == 0 */
1555                         hash = 0;
1556                         break;
1557                 }
1558                 hash = (hash << BLOCK_HASH_SHIFT) ^
1559                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
1560                        le32_to_cpu(here->e_hash);
1561                 here = EXT4_XATTR_NEXT(here);
1562         }
1563         header->h_hash = cpu_to_le32(hash);
1564 }
1565
1566 #undef BLOCK_HASH_SHIFT
1567
1568 int __init
1569 init_ext4_xattr(void)
1570 {
1571         ext4_xattr_cache = mb_cache_create("ext4_xattr", NULL,
1572                 sizeof(struct mb_cache_entry) +
1573                 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6);
1574         if (!ext4_xattr_cache)
1575                 return -ENOMEM;
1576         return 0;
1577 }
1578
1579 void
1580 exit_ext4_xattr(void)
1581 {
1582         if (ext4_xattr_cache)
1583                 mb_cache_destroy(ext4_xattr_cache);
1584         ext4_xattr_cache = NULL;
1585 }