fs/ext4/xattr.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/fs/ext4/xattr.c
   4  *
   5  * Copyright (C) 2001-2003 Andreas Gruenbacher, <[email protected]>
   6  *
   7  * Fix by Harrison Xing <[email protected]>.
   8  * Ext4 code with a lot of help from Eric Jarman <[email protected]>.
   9  * Extended attributes for symlinks and special files added per
  10  *  suggestion of Luka Renko <[email protected]>.
  11  * xattr consolidation Copyright (c) 2004 James Morris <[email protected]>,
  12  *  Red Hat Inc.
  13  * ea-in-inode support by Alex Tomas <[email protected]> aka bzzz
  14  *  and Andreas Gruenbacher <[email protected]>.
  15  */
  16
  17 /*
  18  * Extended attributes are stored directly in inodes (on file systems with
  19  * inodes bigger than 128 bytes) and on additional disk blocks. The i_file_acl
  20  * field contains the block number if an inode uses an additional block. All
  21  * attributes must fit in the inode and one additional block. Blocks that
  22  * contain the identical set of attributes may be shared among several inodes.
  23  * Identical blocks are detected by keeping a cache of blocks that have
  24  * recently been accessed.
  25  *
  26  * The attributes in inodes and on blocks have a different header; the entries
  27  * are stored in the same format:
  28  *
  29  *   +------------------+
  30  *   | header           |
  31  *   | entry 1          | |
  32  *   | entry 2          | | growing downwards
  33  *   | entry 3          | v
  34  *   | four null bytes  |
  35  *   | . . .            |
  36  *   | value 1          | ^
  37  *   | value 3          | | growing upwards
  38  *   | value 2          | |
  39  *   +------------------+
  40  *
  41  * The header is followed by multiple entry descriptors. In disk blocks, the
  42  * entry descriptors are kept sorted. In inodes, they are unsorted. The
  43  * attribute values are aligned to the end of the block in no specific order.
  44  *
  45  * Locking strategy
  46  * ----------------
  47  * EXT4_I(inode)->i_file_acl is protected by EXT4_I(inode)->xattr_sem.
  48  * EA blocks are only changed if they are exclusive to an inode, so
  49  * holding xattr_sem also means that nothing but the EA block's reference
  50  * count can change. Multiple writers to the same block are synchronized
  51  * by the buffer lock.
  52  */
  53
  54 #include <linux/init.h>
  55 #include <linux/fs.h>
  56 #include <linux/slab.h>
  57 #include <linux/mbcache.h>
  58 #include <linux/quotaops.h>
  59 #include <linux/iversion.h>
  60 #include "ext4_jbd2.h"
  61 #include "ext4.h"
  62 #include "xattr.h"
  63 #include "acl.h"
  64
  65 #ifdef EXT4_XATTR_DEBUG
  66 # define ea_idebug(inode, fmt, ...)                                     \
  67         printk(KERN_DEBUG "inode %s:%lu: " fmt "\n",                    \
  68                inode->i_sb->s_id, inode->i_ino, ##__VA_ARGS__)
  69 # define ea_bdebug(bh, fmt, ...)                                        \
  70         printk(KERN_DEBUG "block %pg:%lu: " fmt "\n",                   \
  71                bh->b_bdev, (unsigned long)bh->b_blocknr, ##__VA_ARGS__)
  72 #else
  73 # define ea_idebug(inode, fmt, ...)     no_printk(fmt, ##__VA_ARGS__)
  74 # define ea_bdebug(bh, fmt, ...)        no_printk(fmt, ##__VA_ARGS__)
  75 #endif
  76
  77 static void ext4_xattr_block_cache_insert(struct mb_cache *,
  78                                           struct buffer_head *);
  79 static struct buffer_head *
  80 ext4_xattr_block_cache_find(struct inode *, struct ext4_xattr_header *,
  81                             struct mb_cache_entry **);
  82 static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value,
  83                                     size_t value_count);
  84 static void ext4_xattr_rehash(struct ext4_xattr_header *);
  85
  86 static const struct xattr_handler * const ext4_xattr_handler_map[] = {
  87         [EXT4_XATTR_INDEX_USER]              = &ext4_xattr_user_handler,
  88 #ifdef CONFIG_EXT4_FS_POSIX_ACL
  89         [EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &posix_acl_access_xattr_handler,
  90         [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
  91 #endif
  92         [EXT4_XATTR_INDEX_TRUSTED]           = &ext4_xattr_trusted_handler,
  93 #ifdef CONFIG_EXT4_FS_SECURITY
  94         [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
  95 #endif
  96 };
  97
  98 const struct xattr_handler *ext4_xattr_handlers[] = {
  99         &ext4_xattr_user_handler,
 100         &ext4_xattr_trusted_handler,
 101 #ifdef CONFIG_EXT4_FS_POSIX_ACL
 102         &posix_acl_access_xattr_handler,
 103         &posix_acl_default_xattr_handler,
 104 #endif
 105 #ifdef CONFIG_EXT4_FS_SECURITY
 106         &ext4_xattr_security_handler,
 107 #endif
 108         NULL
 109 };
 110
 111 #define EA_BLOCK_CACHE(inode)   (((struct ext4_sb_info *) \
 112                                 inode->i_sb->s_fs_info)->s_ea_block_cache)
 113
 114 #define EA_INODE_CACHE(inode)   (((struct ext4_sb_info *) \
 115                                 inode->i_sb->s_fs_info)->s_ea_inode_cache)
 116
 117 static int
 118 ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
 119                         struct inode *inode);
 120
 121 #ifdef CONFIG_LOCKDEP
 122 void ext4_xattr_inode_set_class(struct inode *ea_inode)
 123 {
 124         lockdep_set_subclass(&ea_inode->i_rwsem, 1);
 125 }
 126 #endif
 127
 128 static __le32 ext4_xattr_block_csum(struct inode *inode,
 129                                     sector_t block_nr,
 130                                     struct ext4_xattr_header *hdr)
 131 {
 132         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 133         __u32 csum;
 134         __le64 dsk_block_nr = cpu_to_le64(block_nr);
 135         __u32 dummy_csum = 0;
 136         int offset = offsetof(struct ext4_xattr_header, h_checksum);
 137
 138         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&dsk_block_nr,
 139                            sizeof(dsk_block_nr));
 140         csum = ext4_chksum(sbi, csum, (__u8 *)hdr, offset);
 141         csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, sizeof(dummy_csum));
 142         offset += sizeof(dummy_csum);
 143         csum = ext4_chksum(sbi, csum, (__u8 *)hdr + offset,
 144                            EXT4_BLOCK_SIZE(inode->i_sb) - offset);
 145
 146         return cpu_to_le32(csum);
 147 }
 148
 149 static int ext4_xattr_block_csum_verify(struct inode *inode,
 150                                         struct buffer_head *bh)
 151 {
 152         struct ext4_xattr_header *hdr = BHDR(bh);
 153         int ret = 1;
 154
 155         if (ext4_has_metadata_csum(inode->i_sb)) {
 156                 lock_buffer(bh);
 157                 ret = (hdr->h_checksum == ext4_xattr_block_csum(inode,
 158                                                         bh->b_blocknr, hdr));
 159                 unlock_buffer(bh);
 160         }
 161         return ret;
 162 }
 163
 164 static void ext4_xattr_block_csum_set(struct inode *inode,
 165                                       struct buffer_head *bh)
 166 {
 167         if (ext4_has_metadata_csum(inode->i_sb))
 168                 BHDR(bh)->h_checksum = ext4_xattr_block_csum(inode,
 169                                                 bh->b_blocknr, BHDR(bh));
 170 }
 171
 172 static inline const struct xattr_handler *
 173 ext4_xattr_handler(int name_index)
 174 {
 175         const struct xattr_handler *handler = NULL;
 176
 177         if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
 178                 handler = ext4_xattr_handler_map[name_index];
 179         return handler;
 180 }
 181
 182 static int
 183 ext4_xattr_check_entries(struct ext4_xattr_entry *entry, void *end,
 184                          void *value_start)
 185 {
 186         struct ext4_xattr_entry *e = entry;
 187
 188         /* Find the end of the names list */
 189         while (!IS_LAST_ENTRY(e)) {
 190                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(e);
 191                 if ((void *)next >= end)
 192                         return -EFSCORRUPTED;
 193                 if (strnlen(e->e_name, e->e_name_len) != e->e_name_len)
 194                         return -EFSCORRUPTED;
 195                 e = next;
 196         }
 197
 198         /* Check the values */
 199         while (!IS_LAST_ENTRY(entry)) {
 200                 u32 size = le32_to_cpu(entry->e_value_size);
 201
 202                 if (size > EXT4_XATTR_SIZE_MAX)
 203                         return -EFSCORRUPTED;
 204
 205                 if (size != 0 && entry->e_value_inum == 0) {
 206                         u16 offs = le16_to_cpu(entry->e_value_offs);
 207                         void *value;
 208
 209                         /*
 210                          * The value cannot overlap the names, and the value
 211                          * with padding cannot extend beyond 'end'.  Check both
 212                          * the padded and unpadded sizes, since the size may
 213                          * overflow to 0 when adding padding.
 214                          */
 215                         if (offs > end - value_start)
 216                                 return -EFSCORRUPTED;
 217                         value = value_start + offs;
 218                         if (value < (void *)e + sizeof(u32) ||
 219                             size > end - value ||
 220                             EXT4_XATTR_SIZE(size) > end - value)
 221                                 return -EFSCORRUPTED;
 222                 }
 223                 entry = EXT4_XATTR_NEXT(entry);
 224         }
 225
 226         return 0;
 227 }
 228
 229 static inline int
 230 __ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh,
 231                          const char *function, unsigned int line)
 232 {
 233         int error = -EFSCORRUPTED;
 234
 235         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
 236             BHDR(bh)->h_blocks != cpu_to_le32(1))
 237                 goto errout;
 238         if (buffer_verified(bh))
 239                 return 0;
 240
 241         error = -EFSBADCRC;
 242         if (!ext4_xattr_block_csum_verify(inode, bh))
 243                 goto errout;
 244         error = ext4_xattr_check_entries(BFIRST(bh), bh->b_data + bh->b_size,
 245                                          bh->b_data);
 246 errout:
 247         if (error)
 248                 __ext4_error_inode(inode, function, line, 0,
 249                                    "corrupted xattr block %llu",
 250                                    (unsigned long long) bh->b_blocknr);
 251         else
 252                 set_buffer_verified(bh);
 253         return error;
 254 }
 255
 256 #define ext4_xattr_check_block(inode, bh) \
 257         __ext4_xattr_check_block((inode), (bh),  __func__, __LINE__)
 258
 259
 260 static int
 261 __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
 262                          void *end, const char *function, unsigned int line)
 263 {
 264         int error = -EFSCORRUPTED;
 265
 266         if (end - (void *)header < sizeof(*header) + sizeof(u32) ||
 267             (header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)))
 268                 goto errout;
 269         error = ext4_xattr_check_entries(IFIRST(header), end, IFIRST(header));
 270 errout:
 271         if (error)
 272                 __ext4_error_inode(inode, function, line, 0,
 273                                    "corrupted in-inode xattr");
 274         return error;
 275 }
 276
 277 #define xattr_check_inode(inode, header, end) \
 278         __xattr_check_inode((inode), (header), (end), __func__, __LINE__)
 279
 280 static int
 281 xattr_find_entry(struct inode *inode, struct ext4_xattr_entry **pentry,
 282                  void *end, int name_index, const char *name, int sorted)
 283 {
 284         struct ext4_xattr_entry *entry, *next;
 285         size_t name_len;
 286         int cmp = 1;
 287
 288         if (name == NULL)
 289                 return -EINVAL;
 290         name_len = strlen(name);
 291         for (entry = *pentry; !IS_LAST_ENTRY(entry); entry = next) {
 292                 next = EXT4_XATTR_NEXT(entry);
 293                 if ((void *) next >= end) {
 294                         EXT4_ERROR_INODE(inode, "corrupted xattr entries");
 295                         return -EFSCORRUPTED;
 296                 }
 297                 cmp = name_index - entry->e_name_index;
 298                 if (!cmp)
 299                         cmp = name_len - entry->e_name_len;
 300                 if (!cmp)
 301                         cmp = memcmp(name, entry->e_name, name_len);
 302                 if (cmp <= 0 && (sorted || cmp == 0))
 303                         break;
 304         }
 305         *pentry = entry;
 306         return cmp ? -ENODATA : 0;
 307 }
 308
 309 static u32
 310 ext4_xattr_inode_hash(struct ext4_sb_info *sbi, const void *buffer, size_t size)
 311 {
 312         return ext4_chksum(sbi, sbi->s_csum_seed, buffer, size);
 313 }
 314
 315 static u64 ext4_xattr_inode_get_ref(struct inode *ea_inode)
 316 {
 317         return ((u64)ea_inode->i_ctime.tv_sec << 32) |
 318                 (u32) inode_peek_iversion_raw(ea_inode);
 319 }
 320
 321 static void ext4_xattr_inode_set_ref(struct inode *ea_inode, u64 ref_count)
 322 {
 323         ea_inode->i_ctime.tv_sec = (u32)(ref_count >> 32);
 324         inode_set_iversion_raw(ea_inode, ref_count & 0xffffffff);
 325 }
 326
 327 static u32 ext4_xattr_inode_get_hash(struct inode *ea_inode)
 328 {
 329         return (u32)ea_inode->i_atime.tv_sec;
 330 }
 331
 332 static void ext4_xattr_inode_set_hash(struct inode *ea_inode, u32 hash)
 333 {
 334         ea_inode->i_atime.tv_sec = hash;
 335 }
 336
 337 /*
 338  * Read the EA value from an inode.
 339  */
 340 static int ext4_xattr_inode_read(struct inode *ea_inode, void *buf, size_t size)
 341 {
 342         int blocksize = 1 << ea_inode->i_blkbits;
 343         int bh_count = (size + blocksize - 1) >> ea_inode->i_blkbits;
 344         int tail_size = (size % blocksize) ?: blocksize;
 345         struct buffer_head *bhs_inline[8];
 346         struct buffer_head **bhs = bhs_inline;
 347         int i, ret;
 348
 349         if (bh_count > ARRAY_SIZE(bhs_inline)) {
 350                 bhs = kmalloc_array(bh_count, sizeof(*bhs), GFP_NOFS);
 351                 if (!bhs)
 352                         return -ENOMEM;
 353         }
 354
 355         ret = ext4_bread_batch(ea_inode, 0 /* block */, bh_count,
 356                                true /* wait */, bhs);
 357         if (ret)
 358                 goto free_bhs;
 359
 360         for (i = 0; i < bh_count; i++) {
 361                 /* There shouldn't be any holes in ea_inode. */
 362                 if (!bhs[i]) {
 363                         ret = -EFSCORRUPTED;
 364                         goto put_bhs;
 365                 }
 366                 memcpy((char *)buf + blocksize * i, bhs[i]->b_data,
 367                        i < bh_count - 1 ? blocksize : tail_size);
 368         }
 369         ret = 0;
 370 put_bhs:
 371         for (i = 0; i < bh_count; i++)
 372                 brelse(bhs[i]);
 373 free_bhs:
 374         if (bhs != bhs_inline)
 375                 kfree(bhs);
 376         return ret;
 377 }
 378
 379 #define EXT4_XATTR_INODE_GET_PARENT(inode) ((__u32)(inode)->i_mtime.tv_sec)
 380
 381 static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino,
 382                                  u32 ea_inode_hash, struct inode **ea_inode)
 383 {
 384         struct inode *inode;
 385         int err;
 386
 387         inode = ext4_iget(parent->i_sb, ea_ino, EXT4_IGET_NORMAL);
 388         if (IS_ERR(inode)) {
 389                 err = PTR_ERR(inode);
 390                 ext4_error(parent->i_sb,
 391                            "error while reading EA inode %lu err=%d", ea_ino,
 392                            err);
 393                 return err;
 394         }
 395
 396         if (is_bad_inode(inode)) {
 397                 ext4_error(parent->i_sb,
 398                            "error while reading EA inode %lu is_bad_inode",
 399                            ea_ino);
 400                 err = -EIO;
 401                 goto error;
 402         }
 403
 404         if (!(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)) {
 405                 ext4_error(parent->i_sb,
 406                            "EA inode %lu does not have EXT4_EA_INODE_FL flag",
 407                             ea_ino);
 408                 err = -EINVAL;
 409                 goto error;
 410         }
 411
 412         ext4_xattr_inode_set_class(inode);
 413
 414         /*
 415          * Check whether this is an old Lustre-style xattr inode. Lustre
 416          * implementation does not have hash validation, rather it has a
 417          * backpointer from ea_inode to the parent inode.
 418          */
 419         if (ea_inode_hash != ext4_xattr_inode_get_hash(inode) &&
 420             EXT4_XATTR_INODE_GET_PARENT(inode) == parent->i_ino &&
 421             inode->i_generation == parent->i_generation) {
 422                 ext4_set_inode_state(inode, EXT4_STATE_LUSTRE_EA_INODE);
 423                 ext4_xattr_inode_set_ref(inode, 1);
 424         } else {
 425                 inode_lock(inode);
 426                 inode->i_flags |= S_NOQUOTA;
 427                 inode_unlock(inode);
 428         }
 429
 430         *ea_inode = inode;
 431         return 0;
 432 error:
 433         iput(inode);
 434         return err;
 435 }
 436
 437 static int
 438 ext4_xattr_inode_verify_hashes(struct inode *ea_inode,
 439                                struct ext4_xattr_entry *entry, void *buffer,
 440                                size_t size)
 441 {
 442         u32 hash;
 443
 444         /* Verify stored hash matches calculated hash. */
 445         hash = ext4_xattr_inode_hash(EXT4_SB(ea_inode->i_sb), buffer, size);
 446         if (hash != ext4_xattr_inode_get_hash(ea_inode))
 447                 return -EFSCORRUPTED;
 448
 449         if (entry) {
 450                 __le32 e_hash, tmp_data;
 451
 452                 /* Verify entry hash. */
 453                 tmp_data = cpu_to_le32(hash);
 454                 e_hash = ext4_xattr_hash_entry(entry->e_name, entry->e_name_len,
 455                                                &tmp_data, 1);
 456                 if (e_hash != entry->e_hash)
 457                         return -EFSCORRUPTED;
 458         }
 459         return 0;
 460 }
 461
 462 /*
 463  * Read xattr value from the EA inode.
 464  */
 465 static int
 466 ext4_xattr_inode_get(struct inode *inode, struct ext4_xattr_entry *entry,
 467                      void *buffer, size_t size)
 468 {
 469         struct mb_cache *ea_inode_cache = EA_INODE_CACHE(inode);
 470         struct inode *ea_inode;
 471         int err;
 472
 473         err = ext4_xattr_inode_iget(inode, le32_to_cpu(entry->e_value_inum),
 474                                     le32_to_cpu(entry->e_hash), &ea_inode);
 475         if (err) {
 476                 ea_inode = NULL;
 477                 goto out;
 478         }
 479
 480         if (i_size_read(ea_inode) != size) {
 481                 ext4_warning_inode(ea_inode,
 482                                    "ea_inode file size=%llu entry size=%zu",
 483                                    i_size_read(ea_inode), size);
 484                 err = -EFSCORRUPTED;
 485                 goto out;
 486         }
 487
 488         err = ext4_xattr_inode_read(ea_inode, buffer, size);
 489         if (err)
 490                 goto out;
 491
 492         if (!ext4_test_inode_state(ea_inode, EXT4_STATE_LUSTRE_EA_INODE)) {
 493                 err = ext4_xattr_inode_verify_hashes(ea_inode, entry, buffer,
 494                                                      size);
 495                 if (err) {
 496                         ext4_warning_inode(ea_inode,
 497                                            "EA inode hash validation failed");
 498                         goto out;
 499                 }
 500
 501                 if (ea_inode_cache)
 502                         mb_cache_entry_create(ea_inode_cache, GFP_NOFS,
 503                                         ext4_xattr_inode_get_hash(ea_inode),
 504                                         ea_inode->i_ino, true /* reusable */);
 505         }
 506 out:
 507         iput(ea_inode);
 508         return err;
 509 }
 510
 511 static int
 512 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
 513                      void *buffer, size_t buffer_size)
 514 {
 515         struct buffer_head *bh = NULL;
 516         struct ext4_xattr_entry *entry;
 517         size_t size;
 518         void *end;
 519         int error;
 520         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
 521
 522         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 523                   name_index, name, buffer, (long)buffer_size);
 524
 525         if (!EXT4_I(inode)->i_file_acl)
 526                 return -ENODATA;
 527         ea_idebug(inode, "reading block %llu",
 528                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 529         bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
 530         if (IS_ERR(bh))
 531                 return PTR_ERR(bh);
 532         ea_bdebug(bh, "b_count=%d, refcount=%d",
 533                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 534         error = ext4_xattr_check_block(inode, bh);
 535         if (error)
 536                 goto cleanup;
 537         ext4_xattr_block_cache_insert(ea_block_cache, bh);
 538         entry = BFIRST(bh);
 539         end = bh->b_data + bh->b_size;
 540         error = xattr_find_entry(inode, &entry, end, name_index, name, 1);
 541         if (error)
 542                 goto cleanup;
 543         size = le32_to_cpu(entry->e_value_size);
 544         error = -ERANGE;
 545         if (unlikely(size > EXT4_XATTR_SIZE_MAX))
 546                 goto cleanup;
 547         if (buffer) {
 548                 if (size > buffer_size)
 549                         goto cleanup;
 550                 if (entry->e_value_inum) {
 551                         error = ext4_xattr_inode_get(inode, entry, buffer,
 552                                                      size);
 553                         if (error)
 554                                 goto cleanup;
 555                 } else {
 556                         u16 offset = le16_to_cpu(entry->e_value_offs);
 557                         void *p = bh->b_data + offset;
 558
 559                         if (unlikely(p + size > end))
 560                                 goto cleanup;
 561                         memcpy(buffer, p, size);
 562                 }
 563         }
 564         error = size;
 565
 566 cleanup:
 567         brelse(bh);
 568         return error;
 569 }
 570
 571 int
 572 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 573                      void *buffer, size_t buffer_size)
 574 {
 575         struct ext4_xattr_ibody_header *header;
 576         struct ext4_xattr_entry *entry;
 577         struct ext4_inode *raw_inode;
 578         struct ext4_iloc iloc;
 579         size_t size;
 580         void *end;
 581         int error;
 582
 583         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 584                 return -ENODATA;
 585         error = ext4_get_inode_loc(inode, &iloc);
 586         if (error)
 587                 return error;
 588         raw_inode = ext4_raw_inode(&iloc);
 589         header = IHDR(inode, raw_inode);
 590         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 591         error = xattr_check_inode(inode, header, end);
 592         if (error)
 593                 goto cleanup;
 594         entry = IFIRST(header);
 595         error = xattr_find_entry(inode, &entry, end, name_index, name, 0);
 596         if (error)
 597                 goto cleanup;
 598         size = le32_to_cpu(entry->e_value_size);
 599         error = -ERANGE;
 600         if (unlikely(size > EXT4_XATTR_SIZE_MAX))
 601                 goto cleanup;
 602         if (buffer) {
 603                 if (size > buffer_size)
 604                         goto cleanup;
 605                 if (entry->e_value_inum) {
 606                         error = ext4_xattr_inode_get(inode, entry, buffer,
 607                                                      size);
 608                         if (error)
 609                                 goto cleanup;
 610                 } else {
 611                         u16 offset = le16_to_cpu(entry->e_value_offs);
 612                         void *p = (void *)IFIRST(header) + offset;
 613
 614                         if (unlikely(p + size > end))
 615                                 goto cleanup;
 616                         memcpy(buffer, p, size);
 617                 }
 618         }
 619         error = size;
 620
 621 cleanup:
 622         brelse(iloc.bh);
 623         return error;
 624 }
 625
 626 /*
 627  * ext4_xattr_get()
 628  *
 629  * Copy an extended attribute into the buffer
 630  * provided, or compute the buffer size required.
 631  * Buffer is NULL to compute the size of the buffer required.
 632  *
 633  * Returns a negative error number on failure, or the number of bytes
 634  * used / required on success.
 635  */
 636 int
 637 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
 638                void *buffer, size_t buffer_size)
 639 {
 640         int error;
 641
 642         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 643                 return -EIO;
 644
 645         if (strlen(name) > 255)
 646                 return -ERANGE;
 647
 648         down_read(&EXT4_I(inode)->xattr_sem);
 649         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
 650                                      buffer_size);
 651         if (error == -ENODATA)
 652                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
 653                                              buffer_size);
 654         up_read(&EXT4_I(inode)->xattr_sem);
 655         return error;
 656 }
 657
 658 static int
 659 ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,
 660                         char *buffer, size_t buffer_size)
 661 {
 662         size_t rest = buffer_size;
 663
 664         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 665                 const struct xattr_handler *handler =
 666                         ext4_xattr_handler(entry->e_name_index);
 667
 668                 if (handler && (!handler->list || handler->list(dentry))) {
 669                         const char *prefix = handler->prefix ?: handler->name;
 670                         size_t prefix_len = strlen(prefix);
 671                         size_t size = prefix_len + entry->e_name_len + 1;
 672
 673                         if (buffer) {
 674                                 if (size > rest)
 675                                         return -ERANGE;
 676                                 memcpy(buffer, prefix, prefix_len);
 677                                 buffer += prefix_len;
 678                                 memcpy(buffer, entry->e_name, entry->e_name_len);
 679                                 buffer += entry->e_name_len;
 680                                 *buffer++ = 0;
 681                         }
 682                         rest -= size;
 683                 }
 684         }
 685         return buffer_size - rest;  /* total size */
 686 }
 687
 688 static int
 689 ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 690 {
 691         struct inode *inode = d_inode(dentry);
 692         struct buffer_head *bh = NULL;
 693         int error;
 694
 695         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 696                   buffer, (long)buffer_size);
 697
 698         if (!EXT4_I(inode)->i_file_acl)
 699                 return 0;
 700         ea_idebug(inode, "reading block %llu",
 701                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 702         bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
 703         if (IS_ERR(bh))
 704                 return PTR_ERR(bh);
 705         ea_bdebug(bh, "b_count=%d, refcount=%d",
 706                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 707         error = ext4_xattr_check_block(inode, bh);
 708         if (error)
 709                 goto cleanup;
 710         ext4_xattr_block_cache_insert(EA_BLOCK_CACHE(inode), bh);
 711         error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer,
 712                                         buffer_size);
 713 cleanup:
 714         brelse(bh);
 715         return error;
 716 }
 717
 718 static int
 719 ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 720 {
 721         struct inode *inode = d_inode(dentry);
 722         struct ext4_xattr_ibody_header *header;
 723         struct ext4_inode *raw_inode;
 724         struct ext4_iloc iloc;
 725         void *end;
 726         int error;
 727
 728         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 729                 return 0;
 730         error = ext4_get_inode_loc(inode, &iloc);
 731         if (error)
 732                 return error;
 733         raw_inode = ext4_raw_inode(&iloc);
 734         header = IHDR(inode, raw_inode);
 735         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 736         error = xattr_check_inode(inode, header, end);
 737         if (error)
 738                 goto cleanup;
 739         error = ext4_xattr_list_entries(dentry, IFIRST(header),
 740                                         buffer, buffer_size);
 741
 742 cleanup:
 743         brelse(iloc.bh);
 744         return error;
 745 }
 746
 747 /*
 748  * Inode operation listxattr()
 749  *
 750  * d_inode(dentry)->i_rwsem: don't care
 751  *
 752  * Copy a list of attribute names into the buffer
 753  * provided, or compute the buffer size required.
 754  * Buffer is NULL to compute the size of the buffer required.
 755  *
 756  * Returns a negative error number on failure, or the number of bytes
 757  * used / required on success.
 758  */
 759 ssize_t
 760 ext4_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 761 {
 762         int ret, ret2;
 763
 764         down_read(&EXT4_I(d_inode(dentry))->xattr_sem);
 765         ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size);
 766         if (ret < 0)
 767                 goto errout;
 768         if (buffer) {
 769                 buffer += ret;
 770                 buffer_size -= ret;
 771         }
 772         ret = ext4_xattr_block_list(dentry, buffer, buffer_size);
 773         if (ret < 0)
 774                 goto errout;
 775         ret += ret2;
 776 errout:
 777         up_read(&EXT4_I(d_inode(dentry))->xattr_sem);
 778         return ret;
 779 }
 780
 781 /*
 782  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 783  * not set, set it.
 784  */
 785 static void ext4_xattr_update_super_block(handle_t *handle,
 786                                           struct super_block *sb)
 787 {
 788         if (ext4_has_feature_xattr(sb))
 789                 return;
 790
 791         BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
 792         if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
 793                 ext4_set_feature_xattr(sb);
 794                 ext4_handle_dirty_super(handle, sb);
 795         }
 796 }
 797
 798 int ext4_get_inode_usage(struct inode *inode, qsize_t *usage)
 799 {
 800         struct ext4_iloc iloc = { .bh = NULL };
 801         struct buffer_head *bh = NULL;
 802         struct ext4_inode *raw_inode;
 803         struct ext4_xattr_ibody_header *header;
 804         struct ext4_xattr_entry *entry;
 805         qsize_t ea_inode_refs = 0;
 806         void *end;
 807         int ret;
 808
 809         lockdep_assert_held_read(&EXT4_I(inode)->xattr_sem);
 810
 811         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
 812                 ret = ext4_get_inode_loc(inode, &iloc);
 813                 if (ret)
 814                         goto out;
 815                 raw_inode = ext4_raw_inode(&iloc);
 816                 header = IHDR(inode, raw_inode);
 817                 end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 818                 ret = xattr_check_inode(inode, header, end);
 819                 if (ret)
 820                         goto out;
 821
 822                 for (entry = IFIRST(header); !IS_LAST_ENTRY(entry);
 823                      entry = EXT4_XATTR_NEXT(entry))
 824                         if (entry->e_value_inum)
 825                                 ea_inode_refs++;
 826         }
 827
 828         if (EXT4_I(inode)->i_file_acl) {
 829                 bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
 830                 if (IS_ERR(bh)) {
 831                         ret = PTR_ERR(bh);
 832                         bh = NULL;
 833                         goto out;
 834                 }
 835
 836                 ret = ext4_xattr_check_block(inode, bh);
 837                 if (ret)
 838                         goto out;
 839
 840                 for (entry = BFIRST(bh); !IS_LAST_ENTRY(entry);
 841                      entry = EXT4_XATTR_NEXT(entry))
 842                         if (entry->e_value_inum)
 843                                 ea_inode_refs++;
 844         }
 845         *usage = ea_inode_refs + 1;
 846         ret = 0;
 847 out:
 848         brelse(iloc.bh);
 849         brelse(bh);
 850         return ret;
 851 }
 852
 853 static inline size_t round_up_cluster(struct inode *inode, size_t length)
 854 {
 855         struct super_block *sb = inode->i_sb;
 856         size_t cluster_size = 1 << (EXT4_SB(sb)->s_cluster_bits +
 857                                     inode->i_blkbits);
 858         size_t mask = ~(cluster_size - 1);
 859
 860         return (length + cluster_size - 1) & mask;
 861 }
 862
 863 static int ext4_xattr_inode_alloc_quota(struct inode *inode, size_t len)
 864 {
 865         int err;
 866
 867         err = dquot_alloc_inode(inode);
 868         if (err)
 869                 return err;
 870         err = dquot_alloc_space_nodirty(inode, round_up_cluster(inode, len));
 871         if (err)
 872                 dquot_free_inode(inode);
 873         return err;
 874 }
 875
 876 static void ext4_xattr_inode_free_quota(struct inode *parent,
 877                                         struct inode *ea_inode,
 878                                         size_t len)
 879 {
 880         if (ea_inode &&
 881             ext4_test_inode_state(ea_inode, EXT4_STATE_LUSTRE_EA_INODE))
 882                 return;
 883         dquot_free_space_nodirty(parent, round_up_cluster(parent, len));
 884         dquot_free_inode(parent);
 885 }
 886
 887 int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode,
 888                              struct buffer_head *block_bh, size_t value_len,
 889                              bool is_create)
 890 {
 891         int credits;
 892         int blocks;
 893
 894         /*
 895          * 1) Owner inode update
 896          * 2) Ref count update on old xattr block
 897          * 3) new xattr block
 898          * 4) block bitmap update for new xattr block
 899          * 5) group descriptor for new xattr block
 900          * 6) block bitmap update for old xattr block
 901          * 7) group descriptor for old block
 902          *
 903          * 6 & 7 can happen if we have two racing threads T_a and T_b
 904          * which are each trying to set an xattr on inodes I_a and I_b
 905          * which were both initially sharing an xattr block.
 906          */
 907         credits = 7;
 908
 909         /* Quota updates. */
 910         credits += EXT4_MAXQUOTAS_TRANS_BLOCKS(sb);
 911
 912         /*
 913          * In case of inline data, we may push out the data to a block,
 914          * so we need to reserve credits for this eventuality
 915          */
 916         if (inode && ext4_has_inline_data(inode))
 917                 credits += ext4_writepage_trans_blocks(inode) + 1;
 918
 919         /* We are done if ea_inode feature is not enabled. */
 920         if (!ext4_has_feature_ea_inode(sb))
 921                 return credits;
 922
 923         /* New ea_inode, inode map, block bitmap, group descriptor. */
 924         credits += 4;
 925
 926         /* Data blocks. */
 927         blocks = (value_len + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
 928
 929         /* Indirection block or one level of extent tree. */
 930         blocks += 1;
 931
 932         /* Block bitmap and group descriptor updates for each block. */
 933         credits += blocks * 2;
 934
 935         /* Blocks themselves. */
 936         credits += blocks;
 937
 938         if (!is_create) {
 939                 /* Dereference ea_inode holding old xattr value.
 940                  * Old ea_inode, inode map, block bitmap, group descriptor.
 941                  */
 942                 credits += 4;
 943
 944                 /* Data blocks for old ea_inode. */
 945                 blocks = XATTR_SIZE_MAX >> sb->s_blocksize_bits;
 946
 947                 /* Indirection block or one level of extent tree for old
 948                  * ea_inode.
 949                  */
 950                 blocks += 1;
 951
 952                 /* Block bitmap and group descriptor updates for each block. */
 953                 credits += blocks * 2;
 954         }
 955
 956         /* We may need to clone the existing xattr block in which case we need
 957          * to increment ref counts for existing ea_inodes referenced by it.
 958          */
 959         if (block_bh) {
 960                 struct ext4_xattr_entry *entry = BFIRST(block_bh);
 961
 962                 for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry))
 963                         if (entry->e_value_inum)
 964                                 /* Ref count update on ea_inode. */
 965                                 credits += 1;
 966         }
 967         return credits;
 968 }
 969
 970 static int ext4_xattr_ensure_credits(handle_t *handle, struct inode *inode,
 971                                      int credits, struct buffer_head *bh,
 972                                      bool dirty, bool block_csum)
 973 {
 974         int error;
 975
 976         if (!ext4_handle_valid(handle))
 977                 return 0;
 978
 979         if (handle->h_buffer_credits >= credits)
 980                 return 0;
 981
 982         error = ext4_journal_extend(handle, credits - handle->h_buffer_credits);
 983         if (!error)
 984                 return 0;
 985         if (error < 0) {
 986                 ext4_warning(inode->i_sb, "Extend journal (error %d)", error);
 987                 return error;
 988         }
 989
 990         if (bh && dirty) {
 991                 if (block_csum)
 992                         ext4_xattr_block_csum_set(inode, bh);
 993                 error = ext4_handle_dirty_metadata(handle, NULL, bh);
 994                 if (error) {
 995                         ext4_warning(inode->i_sb, "Handle metadata (error %d)",
 996                                      error);
 997                         return error;
 998                 }
 999         }
1000
1001         error = ext4_journal_restart(handle, credits);
1002         if (error) {
1003                 ext4_warning(inode->i_sb, "Restart journal (error %d)", error);
1004                 return error;
1005         }
1006
1007         if (bh) {
1008                 error = ext4_journal_get_write_access(handle, bh);
1009                 if (error) {
1010                         ext4_warning(inode->i_sb,
1011                                      "Get write access failed (error %d)",
1012                                      error);
1013                         return error;
1014                 }
1015         }
1016         return 0;
1017 }
1018
1019 static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode,
1020                                        int ref_change)
1021 {
1022         struct mb_cache *ea_inode_cache = EA_INODE_CACHE(ea_inode);
1023         struct ext4_iloc iloc;
1024         s64 ref_count;
1025         u32 hash;
1026         int ret;
1027
1028         inode_lock(ea_inode);
1029
1030         ret = ext4_reserve_inode_write(handle, ea_inode, &iloc);
1031         if (ret)
1032                 goto out;
1033
1034         ref_count = ext4_xattr_inode_get_ref(ea_inode);
1035         ref_count += ref_change;
1036         ext4_xattr_inode_set_ref(ea_inode, ref_count);
1037
1038         if (ref_change > 0) {
1039                 WARN_ONCE(ref_count <= 0, "EA inode %lu ref_count=%lld",
1040                           ea_inode->i_ino, ref_count);
1041
1042                 if (ref_count == 1) {
1043                         WARN_ONCE(ea_inode->i_nlink, "EA inode %lu i_nlink=%u",
1044                                   ea_inode->i_ino, ea_inode->i_nlink);
1045
1046                         set_nlink(ea_inode, 1);
1047                         ext4_orphan_del(handle, ea_inode);
1048
1049                         if (ea_inode_cache) {
1050                                 hash = ext4_xattr_inode_get_hash(ea_inode);
1051                                 mb_cache_entry_create(ea_inode_cache,
1052                                                       GFP_NOFS, hash,
1053                                                       ea_inode->i_ino,
1054                                                       true /* reusable */);
1055                         }
1056                 }
1057         } else {
1058                 WARN_ONCE(ref_count < 0, "EA inode %lu ref_count=%lld",
1059                           ea_inode->i_ino, ref_count);
1060
1061                 if (ref_count == 0) {
1062                         WARN_ONCE(ea_inode->i_nlink != 1,
1063                                   "EA inode %lu i_nlink=%u",
1064                                   ea_inode->i_ino, ea_inode->i_nlink);
1065
1066                         clear_nlink(ea_inode);
1067                         ext4_orphan_add(handle, ea_inode);
1068
1069                         if (ea_inode_cache) {
1070                                 hash = ext4_xattr_inode_get_hash(ea_inode);
1071                                 mb_cache_entry_delete(ea_inode_cache, hash,
1072                                                       ea_inode->i_ino);
1073                         }
1074                 }
1075         }
1076
1077         ret = ext4_mark_iloc_dirty(handle, ea_inode, &iloc);
1078         if (ret)
1079                 ext4_warning_inode(ea_inode,
1080                                    "ext4_mark_iloc_dirty() failed ret=%d", ret);
1081 out:
1082         inode_unlock(ea_inode);
1083         return ret;
1084 }
1085
1086 static int ext4_xattr_inode_inc_ref(handle_t *handle, struct inode *ea_inode)
1087 {
1088         return ext4_xattr_inode_update_ref(handle, ea_inode, 1);
1089 }
1090
1091 static int ext4_xattr_inode_dec_ref(handle_t *handle, struct inode *ea_inode)
1092 {
1093         return ext4_xattr_inode_update_ref(handle, ea_inode, -1);
1094 }
1095
1096 static int ext4_xattr_inode_inc_ref_all(handle_t *handle, struct inode *parent,
1097                                         struct ext4_xattr_entry *first)
1098 {
1099         struct inode *ea_inode;
1100         struct ext4_xattr_entry *entry;
1101         struct ext4_xattr_entry *failed_entry;
1102         unsigned int ea_ino;
1103         int err, saved_err;
1104
1105         for (entry = first; !IS_LAST_ENTRY(entry);
1106              entry = EXT4_XATTR_NEXT(entry)) {
1107                 if (!entry->e_value_inum)
1108                         continue;
1109                 ea_ino = le32_to_cpu(entry->e_value_inum);
1110                 err = ext4_xattr_inode_iget(parent, ea_ino,
1111                                             le32_to_cpu(entry->e_hash),
1112                                             &ea_inode);
1113                 if (err)
1114                         goto cleanup;
1115                 err = ext4_xattr_inode_inc_ref(handle, ea_inode);
1116                 if (err) {
1117                         ext4_warning_inode(ea_inode, "inc ref error %d", err);
1118                         iput(ea_inode);
1119                         goto cleanup;
1120                 }
1121                 iput(ea_inode);
1122         }
1123         return 0;
1124
1125 cleanup:
1126         saved_err = err;
1127         failed_entry = entry;
1128
1129         for (entry = first; entry != failed_entry;
1130              entry = EXT4_XATTR_NEXT(entry)) {
1131                 if (!entry->e_value_inum)
1132                         continue;
1133                 ea_ino = le32_to_cpu(entry->e_value_inum);
1134                 err = ext4_xattr_inode_iget(parent, ea_ino,
1135                                             le32_to_cpu(entry->e_hash),
1136                                             &ea_inode);
1137                 if (err) {
1138                         ext4_warning(parent->i_sb,
1139                                      "cleanup ea_ino %u iget error %d", ea_ino,
1140                                      err);
1141                         continue;
1142                 }
1143                 err = ext4_xattr_inode_dec_ref(handle, ea_inode);
1144                 if (err)
1145                         ext4_warning_inode(ea_inode, "cleanup dec ref error %d",
1146                                            err);
1147                 iput(ea_inode);
1148         }
1149         return saved_err;
1150 }
1151
1152 static void
1153 ext4_xattr_inode_dec_ref_all(handle_t *handle, struct inode *parent,
1154                              struct buffer_head *bh,
1155                              struct ext4_xattr_entry *first, bool block_csum,
1156                              struct ext4_xattr_inode_array **ea_inode_array,
1157                              int extra_credits, bool skip_quota)
1158 {
1159         struct inode *ea_inode;
1160         struct ext4_xattr_entry *entry;
1161         bool dirty = false;
1162         unsigned int ea_ino;
1163         int err;
1164         int credits;
1165
1166         /* One credit for dec ref on ea_inode, one for orphan list addition, */
1167         credits = 2 + extra_credits;
1168
1169         for (entry = first; !IS_LAST_ENTRY(entry);
1170              entry = EXT4_XATTR_NEXT(entry)) {
1171                 if (!entry->e_value_inum)
1172                         continue;
1173                 ea_ino = le32_to_cpu(entry->e_value_inum);
1174                 err = ext4_xattr_inode_iget(parent, ea_ino,
1175                                             le32_to_cpu(entry->e_hash),
1176                                             &ea_inode);
1177                 if (err)
1178                         continue;
1179
1180                 err = ext4_expand_inode_array(ea_inode_array, ea_inode);
1181                 if (err) {
1182                         ext4_warning_inode(ea_inode,
1183                                            "Expand inode array err=%d", err);
1184                         iput(ea_inode);
1185                         continue;
1186                 }
1187
1188                 err = ext4_xattr_ensure_credits(handle, parent, credits, bh,
1189                                                 dirty, block_csum);
1190                 if (err) {
1191                         ext4_warning_inode(ea_inode, "Ensure credits err=%d",
1192                                            err);
1193                         continue;
1194                 }
1195
1196                 err = ext4_xattr_inode_dec_ref(handle, ea_inode);
1197                 if (err) {
1198                         ext4_warning_inode(ea_inode, "ea_inode dec ref err=%d",
1199                                            err);
1200                         continue;
1201                 }
1202
1203                 if (!skip_quota)
1204                         ext4_xattr_inode_free_quota(parent, ea_inode,
1205                                               le32_to_cpu(entry->e_value_size));
1206
1207                 /*
1208                  * Forget about ea_inode within the same transaction that
1209                  * decrements the ref count. This avoids duplicate decrements in
1210                  * case the rest of the work spills over to subsequent
1211                  * transactions.
1212                  */
1213                 entry->e_value_inum = 0;
1214                 entry->e_value_size = 0;
1215
1216                 dirty = true;
1217         }
1218
1219         if (dirty) {
1220                 /*
1221                  * Note that we are deliberately skipping csum calculation for
1222                  * the final update because we do not expect any journal
1223                  * restarts until xattr block is freed.
1224                  */
1225
1226                 err = ext4_handle_dirty_metadata(handle, NULL, bh);
1227                 if (err)
1228                         ext4_warning_inode(parent,
1229                                            "handle dirty metadata err=%d", err);
1230         }
1231 }
1232
1233 /*
1234  * Release the xattr block BH: If the reference count is > 1, decrement it;
1235  * otherwise free the block.
1236  */
1237 static void
1238 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
1239                          struct buffer_head *bh,
1240                          struct ext4_xattr_inode_array **ea_inode_array,
1241                          int extra_credits)
1242 {
1243         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
1244         u32 hash, ref;
1245         int error = 0;
1246
1247         BUFFER_TRACE(bh, "get_write_access");
1248         error = ext4_journal_get_write_access(handle, bh);
1249         if (error)
1250                 goto out;
1251
1252         lock_buffer(bh);
1253         hash = le32_to_cpu(BHDR(bh)->h_hash);
1254         ref = le32_to_cpu(BHDR(bh)->h_refcount);
1255         if (ref == 1) {
1256                 ea_bdebug(bh, "refcount now=0; freeing");
1257                 /*
1258                  * This must happen under buffer lock for
1259                  * ext4_xattr_block_set() to reliably detect freed block
1260                  */
1261                 if (ea_block_cache)
1262                         mb_cache_entry_delete(ea_block_cache, hash,
1263                                               bh->b_blocknr);
1264                 get_bh(bh);
1265                 unlock_buffer(bh);
1266
1267                 if (ext4_has_feature_ea_inode(inode->i_sb))
1268                         ext4_xattr_inode_dec_ref_all(handle, inode, bh,
1269                                                      BFIRST(bh),
1270                                                      true /* block_csum */,
1271                                                      ea_inode_array,
1272                                                      extra_credits,
1273                                                      true /* skip_quota */);
1274                 ext4_free_blocks(handle, inode, bh, 0, 1,
1275                                  EXT4_FREE_BLOCKS_METADATA |
1276                                  EXT4_FREE_BLOCKS_FORGET);
1277         } else {
1278                 ref--;
1279                 BHDR(bh)->h_refcount = cpu_to_le32(ref);
1280                 if (ref == EXT4_XATTR_REFCOUNT_MAX - 1) {
1281                         struct mb_cache_entry *ce;
1282
1283                         if (ea_block_cache) {
1284                                 ce = mb_cache_entry_get(ea_block_cache, hash,
1285                                                         bh->b_blocknr);
1286                                 if (ce) {
1287                                         ce->e_reusable = 1;
1288                                         mb_cache_entry_put(ea_block_cache, ce);
1289                                 }
1290                         }
1291                 }
1292
1293                 ext4_xattr_block_csum_set(inode, bh);
1294                 /*
1295                  * Beware of this ugliness: Releasing of xattr block references
1296                  * from different inodes can race and so we have to protect
1297                  * from a race where someone else frees the block (and releases
1298                  * its journal_head) before we are done dirtying the buffer. In
1299                  * nojournal mode this race is harmless and we actually cannot
1300                  * call ext4_handle_dirty_metadata() with locked buffer as
1301                  * that function can call sync_dirty_buffer() so for that case
1302                  * we handle the dirtying after unlocking the buffer.
1303                  */
1304                 if (ext4_handle_valid(handle))
1305                         error = ext4_handle_dirty_metadata(handle, inode, bh);
1306                 unlock_buffer(bh);
1307                 if (!ext4_handle_valid(handle))
1308                         error = ext4_handle_dirty_metadata(handle, inode, bh);
1309                 if (IS_SYNC(inode))
1310                         ext4_handle_sync(handle);
1311                 dquot_free_block(inode, EXT4_C2B(EXT4_SB(inode->i_sb), 1));
1312                 ea_bdebug(bh, "refcount now=%d; releasing",
1313                           le32_to_cpu(BHDR(bh)->h_refcount));
1314         }
1315 out:
1316         ext4_std_error(inode->i_sb, error);
1317         return;
1318 }
1319
1320 /*
1321  * Find the available free space for EAs. This also returns the total number of
1322  * bytes used by EA entries.
1323  */
1324 static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
1325                                     size_t *min_offs, void *base, int *total)
1326 {
1327         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1328                 if (!last->e_value_inum && last->e_value_size) {
1329                         size_t offs = le16_to_cpu(last->e_value_offs);
1330                         if (offs < *min_offs)
1331                                 *min_offs = offs;
1332                 }
1333                 if (total)
1334                         *total += EXT4_XATTR_LEN(last->e_name_len);
1335         }
1336         return (*min_offs - ((void *)last - base) - sizeof(__u32));
1337 }
1338
1339 /*
1340  * Write the value of the EA in an inode.
1341  */
1342 static int ext4_xattr_inode_write(handle_t *handle, struct inode *ea_inode,
1343                                   const void *buf, int bufsize)
1344 {
1345         struct buffer_head *bh = NULL;
1346         unsigned long block = 0;
1347         int blocksize = ea_inode->i_sb->s_blocksize;
1348         int max_blocks = (bufsize + blocksize - 1) >> ea_inode->i_blkbits;
1349         int csize, wsize = 0;
1350         int ret = 0;
1351         int retries = 0;
1352
1353 retry:
1354         while (ret >= 0 && ret < max_blocks) {
1355                 struct ext4_map_blocks map;
1356                 map.m_lblk = block += ret;
1357                 map.m_len = max_blocks -= ret;
1358
1359                 ret = ext4_map_blocks(handle, ea_inode, &map,
1360                                       EXT4_GET_BLOCKS_CREATE);
1361                 if (ret <= 0) {
1362                         ext4_mark_inode_dirty(handle, ea_inode);
1363                         if (ret == -ENOSPC &&
1364                             ext4_should_retry_alloc(ea_inode->i_sb, &retries)) {
1365                                 ret = 0;
1366                                 goto retry;
1367                         }
1368                         break;
1369                 }
1370         }
1371
1372         if (ret < 0)
1373                 return ret;
1374
1375         block = 0;
1376         while (wsize < bufsize) {
1377                 if (bh != NULL)
1378                         brelse(bh);
1379                 csize = (bufsize - wsize) > blocksize ? blocksize :
1380                                                                 bufsize - wsize;
1381                 bh = ext4_getblk(handle, ea_inode, block, 0);
1382                 if (IS_ERR(bh))
1383                         return PTR_ERR(bh);
1384                 if (!bh) {
1385                         WARN_ON_ONCE(1);
1386                         EXT4_ERROR_INODE(ea_inode,
1387                                          "ext4_getblk() return bh = NULL");
1388                         return -EFSCORRUPTED;
1389                 }
1390                 ret = ext4_journal_get_write_access(handle, bh);
1391                 if (ret)
1392                         goto out;
1393
1394                 memcpy(bh->b_data, buf, csize);
1395                 set_buffer_uptodate(bh);
1396                 ext4_handle_dirty_metadata(handle, ea_inode, bh);
1397
1398                 buf += csize;
1399                 wsize += csize;
1400                 block += 1;
1401         }
1402
1403         inode_lock(ea_inode);
1404         i_size_write(ea_inode, wsize);
1405         ext4_update_i_disksize(ea_inode, wsize);
1406         inode_unlock(ea_inode);
1407
1408         ext4_mark_inode_dirty(handle, ea_inode);
1409
1410 out:
1411         brelse(bh);
1412
1413         return ret;
1414 }
1415
1416 /*
1417  * Create an inode to store the value of a large EA.
1418  */
1419 static struct inode *ext4_xattr_inode_create(handle_t *handle,
1420                                              struct inode *inode, u32 hash)
1421 {
1422         struct inode *ea_inode = NULL;
1423         uid_t owner[2] = { i_uid_read(inode), i_gid_read(inode) };
1424         int err;
1425
1426         /*
1427          * Let the next inode be the goal, so we try and allocate the EA inode
1428          * in the same group, or nearby one.
1429          */
1430         ea_inode = ext4_new_inode(handle, inode->i_sb->s_root->d_inode,
1431                                   S_IFREG | 0600, NULL, inode->i_ino + 1, owner,
1432                                   EXT4_EA_INODE_FL);
1433         if (!IS_ERR(ea_inode)) {
1434                 ea_inode->i_op = &ext4_file_inode_operations;
1435                 ea_inode->i_fop = &ext4_file_operations;
1436                 ext4_set_aops(ea_inode);
1437                 ext4_xattr_inode_set_class(ea_inode);
1438                 unlock_new_inode(ea_inode);
1439                 ext4_xattr_inode_set_ref(ea_inode, 1);
1440                 ext4_xattr_inode_set_hash(ea_inode, hash);
1441                 err = ext4_mark_inode_dirty(handle, ea_inode);
1442                 if (!err)
1443                         err = ext4_inode_attach_jinode(ea_inode);
1444                 if (err) {
1445                         iput(ea_inode);
1446                         return ERR_PTR(err);
1447                 }
1448
1449                 /*
1450                  * Xattr inodes are shared therefore quota charging is performed
1451                  * at a higher level.
1452                  */
1453                 dquot_free_inode(ea_inode);
1454                 dquot_drop(ea_inode);
1455                 inode_lock(ea_inode);
1456                 ea_inode->i_flags |= S_NOQUOTA;
1457                 inode_unlock(ea_inode);
1458         }
1459
1460         return ea_inode;
1461 }
1462
1463 static struct inode *
1464 ext4_xattr_inode_cache_find(struct inode *inode, const void *value,
1465                             size_t value_len, u32 hash)
1466 {
1467         struct inode *ea_inode;
1468         struct mb_cache_entry *ce;
1469         struct mb_cache *ea_inode_cache = EA_INODE_CACHE(inode);
1470         void *ea_data;
1471
1472         if (!ea_inode_cache)
1473                 return NULL;
1474
1475         ce = mb_cache_entry_find_first(ea_inode_cache, hash);
1476         if (!ce)
1477                 return NULL;
1478
1479         ea_data = ext4_kvmalloc(value_len, GFP_NOFS);
1480         if (!ea_data) {
1481                 mb_cache_entry_put(ea_inode_cache, ce);
1482                 return NULL;
1483         }
1484
1485         while (ce) {
1486                 ea_inode = ext4_iget(inode->i_sb, ce->e_value,
1487                                      EXT4_IGET_NORMAL);
1488                 if (!IS_ERR(ea_inode) &&
1489                     !is_bad_inode(ea_inode) &&
1490                     (EXT4_I(ea_inode)->i_flags & EXT4_EA_INODE_FL) &&
1491                     i_size_read(ea_inode) == value_len &&
1492                     !ext4_xattr_inode_read(ea_inode, ea_data, value_len) &&
1493                     !ext4_xattr_inode_verify_hashes(ea_inode, NULL, ea_data,
1494                                                     value_len) &&
1495                     !memcmp(value, ea_data, value_len)) {
1496                         mb_cache_entry_touch(ea_inode_cache, ce);
1497                         mb_cache_entry_put(ea_inode_cache, ce);
1498                         kvfree(ea_data);
1499                         return ea_inode;
1500                 }
1501
1502                 if (!IS_ERR(ea_inode))
1503                         iput(ea_inode);
1504                 ce = mb_cache_entry_find_next(ea_inode_cache, ce);
1505         }
1506         kvfree(ea_data);
1507         return NULL;
1508 }
1509
1510 /*
1511  * Add value of the EA in an inode.
1512  */
1513 static int ext4_xattr_inode_lookup_create(handle_t *handle, struct inode *inode,
1514                                           const void *value, size_t value_len,
1515                                           struct inode **ret_inode)
1516 {
1517         struct inode *ea_inode;
1518         u32 hash;
1519         int err;
1520
1521         hash = ext4_xattr_inode_hash(EXT4_SB(inode->i_sb), value, value_len);
1522         ea_inode = ext4_xattr_inode_cache_find(inode, value, value_len, hash);
1523         if (ea_inode) {
1524                 err = ext4_xattr_inode_inc_ref(handle, ea_inode);
1525                 if (err) {
1526                         iput(ea_inode);
1527                         return err;
1528                 }
1529
1530                 *ret_inode = ea_inode;
1531                 return 0;
1532         }
1533
1534         /* Create an inode for the EA value */
1535         ea_inode = ext4_xattr_inode_create(handle, inode, hash);
1536         if (IS_ERR(ea_inode))
1537                 return PTR_ERR(ea_inode);
1538
1539         err = ext4_xattr_inode_write(handle, ea_inode, value, value_len);
1540         if (err) {
1541                 ext4_xattr_inode_dec_ref(handle, ea_inode);
1542                 iput(ea_inode);
1543                 return err;
1544         }
1545
1546         if (EA_INODE_CACHE(inode))
1547                 mb_cache_entry_create(EA_INODE_CACHE(inode), GFP_NOFS, hash,
1548                                       ea_inode->i_ino, true /* reusable */);
1549
1550         *ret_inode = ea_inode;
1551         return 0;
1552 }
1553
1554 /*
1555  * Reserve min(block_size/8, 1024) bytes for xattr entries/names if ea_inode
1556  * feature is enabled.
1557  */
1558 #define EXT4_XATTR_BLOCK_RESERVE(inode) min(i_blocksize(inode)/8, 1024U)
1559
1560 static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
1561                                 struct ext4_xattr_search *s,
1562                                 handle_t *handle, struct inode *inode,
1563                                 bool is_block)
1564 {
1565         struct ext4_xattr_entry *last, *next;
1566         struct ext4_xattr_entry *here = s->here;
1567         size_t min_offs = s->end - s->base, name_len = strlen(i->name);
1568         int in_inode = i->in_inode;
1569         struct inode *old_ea_inode = NULL;
1570         struct inode *new_ea_inode = NULL;
1571         size_t old_size, new_size;
1572         int ret;
1573
1574         /* Space used by old and new values. */
1575         old_size = (!s->not_found && !here->e_value_inum) ?
1576                         EXT4_XATTR_SIZE(le32_to_cpu(here->e_value_size)) : 0;
1577         new_size = (i->value && !in_inode) ? EXT4_XATTR_SIZE(i->value_len) : 0;
1578
1579         /*
1580          * Optimization for the simple case when old and new values have the
1581          * same padded sizes. Not applicable if external inodes are involved.
1582          */
1583         if (new_size && new_size == old_size) {
1584                 size_t offs = le16_to_cpu(here->e_value_offs);
1585                 void *val = s->base + offs;
1586
1587                 here->e_value_size = cpu_to_le32(i->value_len);
1588                 if (i->value == EXT4_ZERO_XATTR_VALUE) {
1589                         memset(val, 0, new_size);
1590                 } else {
1591                         memcpy(val, i->value, i->value_len);
1592                         /* Clear padding bytes. */
1593                         memset(val + i->value_len, 0, new_size - i->value_len);
1594                 }
1595                 goto update_hash;
1596         }
1597
1598         /* Compute min_offs and last. */
1599         last = s->first;
1600         for (; !IS_LAST_ENTRY(last); last = next) {
1601                 next = EXT4_XATTR_NEXT(last);
1602                 if ((void *)next >= s->end) {
1603                         EXT4_ERROR_INODE(inode, "corrupted xattr entries");
1604                         ret = -EFSCORRUPTED;
1605                         goto out;
1606                 }
1607                 if (!last->e_value_inum && last->e_value_size) {
1608                         size_t offs = le16_to_cpu(last->e_value_offs);
1609                         if (offs < min_offs)
1610                                 min_offs = offs;
1611                 }
1612         }
1613
1614         /* Check whether we have enough space. */
1615         if (i->value) {
1616                 size_t free;
1617
1618                 free = min_offs - ((void *)last - s->base) - sizeof(__u32);
1619                 if (!s->not_found)
1620                         free += EXT4_XATTR_LEN(name_len) + old_size;
1621
1622                 if (free < EXT4_XATTR_LEN(name_len) + new_size) {
1623                         ret = -ENOSPC;
1624                         goto out;
1625                 }
1626
1627                 /*
1628                  * If storing the value in an external inode is an option,
1629                  * reserve space for xattr entries/names in the external
1630                  * attribute block so that a long value does not occupy the
1631                  * whole space and prevent futher entries being added.
1632                  */
1633                 if (ext4_has_feature_ea_inode(inode->i_sb) &&
1634                     new_size && is_block &&
1635                     (min_offs + old_size - new_size) <
1636                                         EXT4_XATTR_BLOCK_RESERVE(inode)) {
1637                         ret = -ENOSPC;
1638                         goto out;
1639                 }
1640         }
1641
1642         /*
1643          * Getting access to old and new ea inodes is subject to failures.
1644          * Finish that work before doing any modifications to the xattr data.
1645          */
1646         if (!s->not_found && here->e_value_inum) {
1647                 ret = ext4_xattr_inode_iget(inode,
1648                                             le32_to_cpu(here->e_value_inum),
1649                                             le32_to_cpu(here->e_hash),
1650                                             &old_ea_inode);
1651                 if (ret) {
1652                         old_ea_inode = NULL;
1653                         goto out;
1654                 }
1655         }
1656         if (i->value && in_inode) {
1657                 WARN_ON_ONCE(!i->value_len);
1658
1659                 ret = ext4_xattr_inode_alloc_quota(inode, i->value_len);
1660                 if (ret)
1661                         goto out;
1662
1663                 ret = ext4_xattr_inode_lookup_create(handle, inode, i->value,
1664                                                      i->value_len,
1665                                                      &new_ea_inode);
1666                 if (ret) {
1667                         new_ea_inode = NULL;
1668                         ext4_xattr_inode_free_quota(inode, NULL, i->value_len);
1669                         goto out;
1670                 }
1671         }
1672
1673         if (old_ea_inode) {
1674                 /* We are ready to release ref count on the old_ea_inode. */
1675                 ret = ext4_xattr_inode_dec_ref(handle, old_ea_inode);
1676                 if (ret) {
1677                         /* Release newly required ref count on new_ea_inode. */
1678                         if (new_ea_inode) {
1679                                 int err;
1680
1681                                 err = ext4_xattr_inode_dec_ref(handle,
1682                                                                new_ea_inode);
1683                                 if (err)
1684                                         ext4_warning_inode(new_ea_inode,
1685                                                   "dec ref new_ea_inode err=%d",
1686                                                   err);
1687                                 ext4_xattr_inode_free_quota(inode, new_ea_inode,
1688                                                             i->value_len);
1689                         }
1690                         goto out;
1691                 }
1692
1693                 ext4_xattr_inode_free_quota(inode, old_ea_inode,
1694                                             le32_to_cpu(here->e_value_size));
1695         }
1696
1697         /* No failures allowed past this point. */
1698
1699         if (!s->not_found && here->e_value_size && !here->e_value_inum) {
1700                 /* Remove the old value. */
1701                 void *first_val = s->base + min_offs;
1702                 size_t offs = le16_to_cpu(here->e_value_offs);
1703                 void *val = s->base + offs;
1704
1705                 memmove(first_val + old_size, first_val, val - first_val);
1706                 memset(first_val, 0, old_size);
1707                 min_offs += old_size;
1708
1709                 /* Adjust all value offsets. */
1710                 last = s->first;
1711                 while (!IS_LAST_ENTRY(last)) {
1712                         size_t o = le16_to_cpu(last->e_value_offs);
1713
1714                         if (!last->e_value_inum &&
1715                             last->e_value_size && o < offs)
1716                                 last->e_value_offs = cpu_to_le16(o + old_size);
1717                         last = EXT4_XATTR_NEXT(last);
1718                 }
1719         }
1720
1721         if (!i->value) {
1722                 /* Remove old name. */
1723                 size_t size = EXT4_XATTR_LEN(name_len);
1724
1725                 last = ENTRY((void *)last - size);
1726                 memmove(here, (void *)here + size,
1727                         (void *)last - (void *)here + sizeof(__u32));
1728                 memset(last, 0, size);
1729         } else if (s->not_found) {
1730                 /* Insert new name. */
1731                 size_t size = EXT4_XATTR_LEN(name_len);
1732                 size_t rest = (void *)last - (void *)here + sizeof(__u32);
1733
1734                 memmove((void *)here + size, here, rest);
1735                 memset(here, 0, size);
1736                 here->e_name_index = i->name_index;
1737                 here->e_name_len = name_len;
1738                 memcpy(here->e_name, i->name, name_len);
1739         } else {
1740                 /* This is an update, reset value info. */
1741                 here->e_value_inum = 0;
1742                 here->e_value_offs = 0;
1743                 here->e_value_size = 0;
1744         }
1745
1746         if (i->value) {
1747                 /* Insert new value. */
1748                 if (in_inode) {
1749                         here->e_value_inum = cpu_to_le32(new_ea_inode->i_ino);
1750                 } else if (i->value_len) {
1751                         void *val = s->base + min_offs - new_size;
1752
1753                         here->e_value_offs = cpu_to_le16(min_offs - new_size);
1754                         if (i->value == EXT4_ZERO_XATTR_VALUE) {
1755                                 memset(val, 0, new_size);
1756                         } else {
1757                                 memcpy(val, i->value, i->value_len);
1758                                 /* Clear padding bytes. */
1759                                 memset(val + i->value_len, 0,
1760                                        new_size - i->value_len);
1761                         }
1762                 }
1763                 here->e_value_size = cpu_to_le32(i->value_len);
1764         }
1765
1766 update_hash:
1767         if (i->value) {
1768                 __le32 hash = 0;
1769
1770                 /* Entry hash calculation. */
1771                 if (in_inode) {
1772                         __le32 crc32c_hash;
1773
1774                         /*
1775                          * Feed crc32c hash instead of the raw value for entry
1776                          * hash calculation. This is to avoid walking
1777                          * potentially long value buffer again.
1778                          */
1779                         crc32c_hash = cpu_to_le32(
1780                                        ext4_xattr_inode_get_hash(new_ea_inode));
1781                         hash = ext4_xattr_hash_entry(here->e_name,
1782                                                      here->e_name_len,
1783                                                      &crc32c_hash, 1);
1784                 } else if (is_block) {
1785                         __le32 *value = s->base + le16_to_cpu(
1786                                                         here->e_value_offs);
1787
1788                         hash = ext4_xattr_hash_entry(here->e_name,
1789                                                      here->e_name_len, value,
1790                                                      new_size >> 2);
1791                 }
1792                 here->e_hash = hash;
1793         }
1794
1795         if (is_block)
1796                 ext4_xattr_rehash((struct ext4_xattr_header *)s->base);
1797
1798         ret = 0;
1799 out:
1800         iput(old_ea_inode);
1801         iput(new_ea_inode);
1802         return ret;
1803 }
1804
1805 struct ext4_xattr_block_find {
1806         struct ext4_xattr_search s;
1807         struct buffer_head *bh;
1808 };
1809
1810 static int
1811 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
1812                       struct ext4_xattr_block_find *bs)
1813 {
1814         struct super_block *sb = inode->i_sb;
1815         int error;
1816
1817         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
1818                   i->name_index, i->name, i->value, (long)i->value_len);
1819
1820         if (EXT4_I(inode)->i_file_acl) {
1821                 /* The inode already has an extended attribute block. */
1822                 bs->bh = ext4_sb_bread(sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
1823                 if (IS_ERR(bs->bh))
1824                         return PTR_ERR(bs->bh);
1825                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
1826                         atomic_read(&(bs->bh->b_count)),
1827                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
1828                 error = ext4_xattr_check_block(inode, bs->bh);
1829                 if (error)
1830                         return error;
1831                 /* Find the named attribute. */
1832                 bs->s.base = BHDR(bs->bh);
1833                 bs->s.first = BFIRST(bs->bh);
1834                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
1835                 bs->s.here = bs->s.first;
1836                 error = xattr_find_entry(inode, &bs->s.here, bs->s.end,
1837                                          i->name_index, i->name, 1);
1838                 if (error && error != -ENODATA)
1839                         return error;
1840                 bs->s.not_found = error;
1841         }
1842         return 0;
1843 }
1844
1845 static int
1846 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
1847                      struct ext4_xattr_info *i,
1848                      struct ext4_xattr_block_find *bs)
1849 {
1850         struct super_block *sb = inode->i_sb;
1851         struct buffer_head *new_bh = NULL;
1852         struct ext4_xattr_search s_copy = bs->s;
1853         struct ext4_xattr_search *s = &s_copy;
1854         struct mb_cache_entry *ce = NULL;
1855         int error = 0;
1856         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
1857         struct inode *ea_inode = NULL, *tmp_inode;
1858         size_t old_ea_inode_quota = 0;
1859         unsigned int ea_ino;
1860
1861
1862 #define header(x) ((struct ext4_xattr_header *)(x))
1863
1864         if (s->base) {
1865                 BUFFER_TRACE(bs->bh, "get_write_access");
1866                 error = ext4_journal_get_write_access(handle, bs->bh);
1867                 if (error)
1868                         goto cleanup;
1869                 lock_buffer(bs->bh);
1870
1871                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
1872                         __u32 hash = le32_to_cpu(BHDR(bs->bh)->h_hash);
1873
1874                         /*
1875                          * This must happen under buffer lock for
1876                          * ext4_xattr_block_set() to reliably detect modified
1877                          * block
1878                          */
1879                         if (ea_block_cache)
1880                                 mb_cache_entry_delete(ea_block_cache, hash,
1881                                                       bs->bh->b_blocknr);
1882                         ea_bdebug(bs->bh, "modifying in-place");
1883                         error = ext4_xattr_set_entry(i, s, handle, inode,
1884                                                      true /* is_block */);
1885                         ext4_xattr_block_csum_set(inode, bs->bh);
1886                         unlock_buffer(bs->bh);
1887                         if (error == -EFSCORRUPTED)
1888                                 goto bad_block;
1889                         if (!error)
1890                                 error = ext4_handle_dirty_metadata(handle,
1891                                                                    inode,
1892                                                                    bs->bh);
1893                         if (error)
1894                                 goto cleanup;
1895                         goto inserted;
1896                 } else {
1897                         int offset = (char *)s->here - bs->bh->b_data;
1898
1899                         unlock_buffer(bs->bh);
1900                         ea_bdebug(bs->bh, "cloning");
1901                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
1902                         error = -ENOMEM;
1903                         if (s->base == NULL)
1904                                 goto cleanup;
1905                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
1906                         s->first = ENTRY(header(s->base)+1);
1907                         header(s->base)->h_refcount = cpu_to_le32(1);
1908                         s->here = ENTRY(s->base + offset);
1909                         s->end = s->base + bs->bh->b_size;
1910
1911                         /*
1912                          * If existing entry points to an xattr inode, we need
1913                          * to prevent ext4_xattr_set_entry() from decrementing
1914                          * ref count on it because the reference belongs to the
1915                          * original block. In this case, make the entry look
1916                          * like it has an empty value.
1917                          */
1918                         if (!s->not_found && s->here->e_value_inum) {
1919                                 ea_ino = le32_to_cpu(s->here->e_value_inum);
1920                                 error = ext4_xattr_inode_iget(inode, ea_ino,
1921                                               le32_to_cpu(s->here->e_hash),
1922                                               &tmp_inode);
1923                                 if (error)
1924                                         goto cleanup;
1925
1926                                 if (!ext4_test_inode_state(tmp_inode,
1927                                                 EXT4_STATE_LUSTRE_EA_INODE)) {
1928                                         /*
1929                                          * Defer quota free call for previous
1930                                          * inode until success is guaranteed.
1931                                          */
1932                                         old_ea_inode_quota = le32_to_cpu(
1933                                                         s->here->e_value_size);
1934                                 }
1935                                 iput(tmp_inode);
1936
1937                                 s->here->e_value_inum = 0;
1938                                 s->here->e_value_size = 0;
1939                         }
1940                 }
1941         } else {
1942                 /* Allocate a buffer where we construct the new block. */
1943                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
1944                 /* assert(header == s->base) */
1945                 error = -ENOMEM;
1946                 if (s->base == NULL)
1947                         goto cleanup;
1948                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1949                 header(s->base)->h_blocks = cpu_to_le32(1);
1950                 header(s->base)->h_refcount = cpu_to_le32(1);
1951                 s->first = ENTRY(header(s->base)+1);
1952                 s->here = ENTRY(header(s->base)+1);
1953                 s->end = s->base + sb->s_blocksize;
1954         }
1955
1956         error = ext4_xattr_set_entry(i, s, handle, inode, true /* is_block */);
1957         if (error == -EFSCORRUPTED)
1958                 goto bad_block;
1959         if (error)
1960                 goto cleanup;
1961
1962         if (i->value && s->here->e_value_inum) {
1963                 /*
1964                  * A ref count on ea_inode has been taken as part of the call to
1965                  * ext4_xattr_set_entry() above. We would like to drop this
1966                  * extra ref but we have to wait until the xattr block is
1967                  * initialized and has its own ref count on the ea_inode.
1968                  */
1969                 ea_ino = le32_to_cpu(s->here->e_value_inum);
1970                 error = ext4_xattr_inode_iget(inode, ea_ino,
1971                                               le32_to_cpu(s->here->e_hash),
1972                                               &ea_inode);
1973                 if (error) {
1974                         ea_inode = NULL;
1975                         goto cleanup;
1976                 }
1977         }
1978
1979 inserted:
1980         if (!IS_LAST_ENTRY(s->first)) {
1981                 new_bh = ext4_xattr_block_cache_find(inode, header(s->base),
1982                                                      &ce);
1983                 if (new_bh) {
1984                         /* We found an identical block in the cache. */
1985                         if (new_bh == bs->bh)
1986                                 ea_bdebug(new_bh, "keeping");
1987                         else {
1988                                 u32 ref;
1989
1990                                 WARN_ON_ONCE(dquot_initialize_needed(inode));
1991
1992                                 /* The old block is released after updating
1993                                    the inode. */
1994                                 error = dquot_alloc_block(inode,
1995                                                 EXT4_C2B(EXT4_SB(sb), 1));
1996                                 if (error)
1997                                         goto cleanup;
1998                                 BUFFER_TRACE(new_bh, "get_write_access");
1999                                 error = ext4_journal_get_write_access(handle,
2000                                                                       new_bh);
2001                                 if (error)
2002                                         goto cleanup_dquot;
2003                                 lock_buffer(new_bh);
2004                                 /*
2005                                  * We have to be careful about races with
2006                                  * freeing, rehashing or adding references to
2007                                  * xattr block. Once we hold buffer lock xattr
2008                                  * block's state is stable so we can check
2009                                  * whether the block got freed / rehashed or
2010                                  * not.  Since we unhash mbcache entry under
2011                                  * buffer lock when freeing / rehashing xattr
2012                                  * block, checking whether entry is still
2013                                  * hashed is reliable. Same rules hold for
2014                                  * e_reusable handling.
2015                                  */
2016                                 if (hlist_bl_unhashed(&ce->e_hash_list) ||
2017                                     !ce->e_reusable) {
2018                                         /*
2019                                          * Undo everything and check mbcache
2020                                          * again.
2021                                          */
2022                                         unlock_buffer(new_bh);
2023                                         dquot_free_block(inode,
2024                                                          EXT4_C2B(EXT4_SB(sb),
2025                                                                   1));
2026                                         brelse(new_bh);
2027                                         mb_cache_entry_put(ea_block_cache, ce);
2028                                         ce = NULL;
2029                                         new_bh = NULL;
2030                                         goto inserted;
2031                                 }
2032                                 ref = le32_to_cpu(BHDR(new_bh)->h_refcount) + 1;
2033                                 BHDR(new_bh)->h_refcount = cpu_to_le32(ref);
2034                                 if (ref >= EXT4_XATTR_REFCOUNT_MAX)
2035                                         ce->e_reusable = 0;
2036                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
2037                                           ref);
2038                                 ext4_xattr_block_csum_set(inode, new_bh);
2039                                 unlock_buffer(new_bh);
2040                                 error = ext4_handle_dirty_metadata(handle,
2041                                                                    inode,
2042                                                                    new_bh);
2043                                 if (error)
2044                                         goto cleanup_dquot;
2045                         }
2046                         mb_cache_entry_touch(ea_block_cache, ce);
2047                         mb_cache_entry_put(ea_block_cache, ce);
2048                         ce = NULL;
2049                 } else if (bs->bh && s->base == bs->bh->b_data) {
2050                         /* We were modifying this block in-place. */
2051                         ea_bdebug(bs->bh, "keeping this block");
2052                         ext4_xattr_block_cache_insert(ea_block_cache, bs->bh);
2053                         new_bh = bs->bh;
2054                         get_bh(new_bh);
2055                 } else {
2056                         /* We need to allocate a new block */
2057                         ext4_fsblk_t goal, block;
2058
2059                         WARN_ON_ONCE(dquot_initialize_needed(inode));
2060
2061                         goal = ext4_group_first_block_no(sb,
2062                                                 EXT4_I(inode)->i_block_group);
2063
2064                         /* non-extent files can't have physical blocks past 2^32 */
2065                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
2066                                 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
2067
2068                         block = ext4_new_meta_blocks(handle, inode, goal, 0,
2069                                                      NULL, &error);
2070                         if (error)
2071                                 goto cleanup;
2072
2073                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
2074                                 BUG_ON(block > EXT4_MAX_BLOCK_FILE_PHYS);
2075
2076                         ea_idebug(inode, "creating block %llu",
2077                                   (unsigned long long)block);
2078
2079                         new_bh = sb_getblk(sb, block);
2080                         if (unlikely(!new_bh)) {
2081                                 error = -ENOMEM;
2082 getblk_failed:
2083                                 ext4_free_blocks(handle, inode, NULL, block, 1,
2084                                                  EXT4_FREE_BLOCKS_METADATA);
2085                                 goto cleanup;
2086                         }
2087                         error = ext4_xattr_inode_inc_ref_all(handle, inode,
2088                                                       ENTRY(header(s->base)+1));
2089                         if (error)
2090                                 goto getblk_failed;
2091                         if (ea_inode) {
2092                                 /* Drop the extra ref on ea_inode. */
2093                                 error = ext4_xattr_inode_dec_ref(handle,
2094                                                                  ea_inode);
2095                                 if (error)
2096                                         ext4_warning_inode(ea_inode,
2097                                                            "dec ref error=%d",
2098                                                            error);
2099                                 iput(ea_inode);
2100                                 ea_inode = NULL;
2101                         }
2102
2103                         lock_buffer(new_bh);
2104                         error = ext4_journal_get_create_access(handle, new_bh);
2105                         if (error) {
2106                                 unlock_buffer(new_bh);
2107                                 error = -EIO;
2108                                 goto getblk_failed;
2109                         }
2110                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
2111                         ext4_xattr_block_csum_set(inode, new_bh);
2112                         set_buffer_uptodate(new_bh);
2113                         unlock_buffer(new_bh);
2114                         ext4_xattr_block_cache_insert(ea_block_cache, new_bh);
2115                         error = ext4_handle_dirty_metadata(handle, inode,
2116                                                            new_bh);
2117                         if (error)
2118                                 goto cleanup;
2119                 }
2120         }
2121
2122         if (old_ea_inode_quota)
2123                 ext4_xattr_inode_free_quota(inode, NULL, old_ea_inode_quota);
2124
2125         /* Update the inode. */
2126         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
2127
2128         /* Drop the previous xattr block. */
2129         if (bs->bh && bs->bh != new_bh) {
2130                 struct ext4_xattr_inode_array *ea_inode_array = NULL;
2131
2132                 ext4_xattr_release_block(handle, inode, bs->bh,
2133                                          &ea_inode_array,
2134                                          0 /* extra_credits */);
2135                 ext4_xattr_inode_array_free(ea_inode_array);
2136         }
2137         error = 0;
2138
2139 cleanup:
2140         if (ea_inode) {
2141                 int error2;
2142
2143                 error2 = ext4_xattr_inode_dec_ref(handle, ea_inode);
2144                 if (error2)
2145                         ext4_warning_inode(ea_inode, "dec ref error=%d",
2146                                            error2);
2147
2148                 /* If there was an error, revert the quota charge. */
2149                 if (error)
2150                         ext4_xattr_inode_free_quota(inode, ea_inode,
2151                                                     i_size_read(ea_inode));
2152                 iput(ea_inode);
2153         }
2154         if (ce)
2155                 mb_cache_entry_put(ea_block_cache, ce);
2156         brelse(new_bh);
2157         if (!(bs->bh && s->base == bs->bh->b_data))
2158                 kfree(s->base);
2159
2160         return error;
2161
2162 cleanup_dquot:
2163         dquot_free_block(inode, EXT4_C2B(EXT4_SB(sb), 1));
2164         goto cleanup;
2165
2166 bad_block:
2167         EXT4_ERROR_INODE(inode, "bad block %llu",
2168                          EXT4_I(inode)->i_file_acl);
2169         goto cleanup;
2170
2171 #undef header
2172 }
2173
2174 int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
2175                           struct ext4_xattr_ibody_find *is)
2176 {
2177         struct ext4_xattr_ibody_header *header;
2178         struct ext4_inode *raw_inode;
2179         int error;
2180
2181         if (EXT4_I(inode)->i_extra_isize == 0)
2182                 return 0;
2183         raw_inode = ext4_raw_inode(&is->iloc);
2184         header = IHDR(inode, raw_inode);
2185         is->s.base = is->s.first = IFIRST(header);
2186         is->s.here = is->s.first;
2187         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
2188         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
2189                 error = xattr_check_inode(inode, header, is->s.end);
2190                 if (error)
2191                         return error;
2192                 /* Find the named attribute. */
2193                 error = xattr_find_entry(inode, &is->s.here, is->s.end,
2194                                          i->name_index, i->name, 0);
2195                 if (error && error != -ENODATA)
2196                         return error;
2197                 is->s.not_found = error;
2198         }
2199         return 0;
2200 }
2201
2202 int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode,
2203                                 struct ext4_xattr_info *i,
2204                                 struct ext4_xattr_ibody_find *is)
2205 {
2206         struct ext4_xattr_ibody_header *header;
2207         struct ext4_xattr_search *s = &is->s;
2208         int error;
2209
2210         if (EXT4_I(inode)->i_extra_isize == 0)
2211                 return -ENOSPC;
2212         error = ext4_xattr_set_entry(i, s, handle, inode, false /* is_block */);
2213         if (error)
2214                 return error;
2215         header = IHDR(inode, ext4_raw_inode(&is->iloc));
2216         if (!IS_LAST_ENTRY(s->first)) {
2217                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
2218                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
2219         } else {
2220                 header->h_magic = cpu_to_le32(0);
2221                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
2222         }
2223         return 0;
2224 }
2225
2226 static int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
2227                                 struct ext4_xattr_info *i,
2228                                 struct ext4_xattr_ibody_find *is)
2229 {
2230         struct ext4_xattr_ibody_header *header;
2231         struct ext4_xattr_search *s = &is->s;
2232         int error;
2233
2234         if (EXT4_I(inode)->i_extra_isize == 0)
2235                 return -ENOSPC;
2236         error = ext4_xattr_set_entry(i, s, handle, inode, false /* is_block */);
2237         if (error)
2238                 return error;
2239         header = IHDR(inode, ext4_raw_inode(&is->iloc));
2240         if (!IS_LAST_ENTRY(s->first)) {
2241                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
2242                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
2243         } else {
2244                 header->h_magic = cpu_to_le32(0);
2245                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
2246         }
2247         return 0;
2248 }
2249
2250 static int ext4_xattr_value_same(struct ext4_xattr_search *s,
2251                                  struct ext4_xattr_info *i)
2252 {
2253         void *value;
2254
2255         /* When e_value_inum is set the value is stored externally. */
2256         if (s->here->e_value_inum)
2257                 return 0;
2258         if (le32_to_cpu(s->here->e_value_size) != i->value_len)
2259                 return 0;
2260         value = ((void *)s->base) + le16_to_cpu(s->here->e_value_offs);
2261         return !memcmp(value, i->value, i->value_len);
2262 }
2263
2264 static struct buffer_head *ext4_xattr_get_block(struct inode *inode)
2265 {
2266         struct buffer_head *bh;
2267         int error;
2268
2269         if (!EXT4_I(inode)->i_file_acl)
2270                 return NULL;
2271         bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
2272         if (IS_ERR(bh))
2273                 return bh;
2274         error = ext4_xattr_check_block(inode, bh);
2275         if (error) {
2276                 brelse(bh);
2277                 return ERR_PTR(error);
2278         }
2279         return bh;
2280 }
2281
2282 /*
2283  * ext4_xattr_set_handle()
2284  *
2285  * Create, replace or remove an extended attribute for this inode.  Value
2286  * is NULL to remove an existing extended attribute, and non-NULL to
2287  * either replace an existing extended attribute, or create a new extended
2288  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
2289  * specify that an extended attribute must exist and must not exist
2290  * previous to the call, respectively.
2291  *
2292  * Returns 0, or a negative error number on failure.
2293  */
2294 int
2295 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
2296                       const char *name, const void *value, size_t value_len,
2297                       int flags)
2298 {
2299         struct ext4_xattr_info i = {
2300                 .name_index = name_index,
2301                 .name = name,
2302                 .value = value,
2303                 .value_len = value_len,
2304                 .in_inode = 0,
2305         };
2306         struct ext4_xattr_ibody_find is = {
2307                 .s = { .not_found = -ENODATA, },
2308         };
2309         struct ext4_xattr_block_find bs = {
2310                 .s = { .not_found = -ENODATA, },
2311         };
2312         int no_expand;
2313         int error;
2314
2315         if (!name)
2316                 return -EINVAL;
2317         if (strlen(name) > 255)
2318                 return -ERANGE;
2319
2320         ext4_write_lock_xattr(inode, &no_expand);
2321
2322         /* Check journal credits under write lock. */
2323         if (ext4_handle_valid(handle)) {
2324                 struct buffer_head *bh;
2325                 int credits;
2326
2327                 bh = ext4_xattr_get_block(inode);
2328                 if (IS_ERR(bh)) {
2329                         error = PTR_ERR(bh);
2330                         goto cleanup;
2331                 }
2332
2333                 credits = __ext4_xattr_set_credits(inode->i_sb, inode, bh,
2334                                                    value_len,
2335                                                    flags & XATTR_CREATE);
2336                 brelse(bh);
2337
2338                 if (!ext4_handle_has_enough_credits(handle, credits)) {
2339                         error = -ENOSPC;
2340                         goto cleanup;
2341                 }
2342         }
2343
2344         error = ext4_reserve_inode_write(handle, inode, &is.iloc);
2345         if (error)
2346                 goto cleanup;
2347
2348         if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) {
2349                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
2350                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
2351                 ext4_clear_inode_state(inode, EXT4_STATE_NEW);
2352         }
2353
2354         error = ext4_xattr_ibody_find(inode, &i, &is);
2355         if (error)
2356                 goto cleanup;
2357         if (is.s.not_found)
2358                 error = ext4_xattr_block_find(inode, &i, &bs);
2359         if (error)
2360                 goto cleanup;
2361         if (is.s.not_found && bs.s.not_found) {
2362                 error = -ENODATA;
2363                 if (flags & XATTR_REPLACE)
2364                         goto cleanup;
2365                 error = 0;
2366                 if (!value)
2367                         goto cleanup;
2368         } else {
2369                 error = -EEXIST;
2370                 if (flags & XATTR_CREATE)
2371                         goto cleanup;
2372         }
2373
2374         if (!value) {
2375                 if (!is.s.not_found)
2376                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
2377                 else if (!bs.s.not_found)
2378                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
2379         } else {
2380                 error = 0;
2381                 /* Xattr value did not change? Save us some work and bail out */
2382                 if (!is.s.not_found && ext4_xattr_value_same(&is.s, &i))
2383                         goto cleanup;
2384                 if (!bs.s.not_found && ext4_xattr_value_same(&bs.s, &i))
2385                         goto cleanup;
2386
2387                 if (ext4_has_feature_ea_inode(inode->i_sb) &&
2388                     (EXT4_XATTR_SIZE(i.value_len) >
2389                         EXT4_XATTR_MIN_LARGE_EA_SIZE(inode->i_sb->s_blocksize)))
2390                         i.in_inode = 1;
2391 retry_inode:
2392                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
2393                 if (!error && !bs.s.not_found) {
2394                         i.value = NULL;
2395                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
2396                 } else if (error == -ENOSPC) {
2397                         if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
2398                                 brelse(bs.bh);
2399                                 bs.bh = NULL;
2400                                 error = ext4_xattr_block_find(inode, &i, &bs);
2401                                 if (error)
2402                                         goto cleanup;
2403                         }
2404                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
2405                         if (!error && !is.s.not_found) {
2406                                 i.value = NULL;
2407                                 error = ext4_xattr_ibody_set(handle, inode, &i,
2408                                                              &is);
2409                         } else if (error == -ENOSPC) {
2410                                 /*
2411                                  * Xattr does not fit in the block, store at
2412                                  * external inode if possible.
2413                                  */
2414                                 if (ext4_has_feature_ea_inode(inode->i_sb) &&
2415                                     !i.in_inode) {
2416                                         i.in_inode = 1;
2417                                         goto retry_inode;
2418                                 }
2419                         }
2420                 }
2421         }
2422         if (!error) {
2423                 ext4_xattr_update_super_block(handle, inode->i_sb);
2424                 inode->i_ctime = current_time(inode);
2425                 if (!value)
2426                         no_expand = 0;
2427                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
2428                 /*
2429                  * The bh is consumed by ext4_mark_iloc_dirty, even with
2430                  * error != 0.
2431                  */
2432                 is.iloc.bh = NULL;
2433                 if (IS_SYNC(inode))
2434                         ext4_handle_sync(handle);
2435         }
2436
2437 cleanup:
2438         brelse(is.iloc.bh);
2439         brelse(bs.bh);
2440         ext4_write_unlock_xattr(inode, &no_expand);
2441         return error;
2442 }
2443
2444 int ext4_xattr_set_credits(struct inode *inode, size_t value_len,
2445                            bool is_create, int *credits)
2446 {
2447         struct buffer_head *bh;
2448         int err;
2449
2450         *credits = 0;
2451
2452         if (!EXT4_SB(inode->i_sb)->s_journal)
2453                 return 0;
2454
2455         down_read(&EXT4_I(inode)->xattr_sem);
2456
2457         bh = ext4_xattr_get_block(inode);
2458         if (IS_ERR(bh)) {
2459                 err = PTR_ERR(bh);
2460         } else {
2461                 *credits = __ext4_xattr_set_credits(inode->i_sb, inode, bh,
2462                                                     value_len, is_create);
2463                 brelse(bh);
2464                 err = 0;
2465         }
2466
2467         up_read(&EXT4_I(inode)->xattr_sem);
2468         return err;
2469 }
2470
2471 /*
2472  * ext4_xattr_set()
2473  *
2474  * Like ext4_xattr_set_handle, but start from an inode. This extended
2475  * attribute modification is a filesystem transaction by itself.
2476  *
2477  * Returns 0, or a negative error number on failure.
2478  */
2479 int
2480 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
2481                const void *value, size_t value_len, int flags)
2482 {
2483         handle_t *handle;
2484         struct super_block *sb = inode->i_sb;
2485         int error, retries = 0;
2486         int credits;
2487
2488         error = dquot_initialize(inode);
2489         if (error)
2490                 return error;
2491
2492 retry:
2493         error = ext4_xattr_set_credits(inode, value_len, flags & XATTR_CREATE,
2494                                        &credits);
2495         if (error)
2496                 return error;
2497
2498         handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
2499         if (IS_ERR(handle)) {
2500                 error = PTR_ERR(handle);
2501         } else {
2502                 int error2;
2503
2504                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
2505                                               value, value_len, flags);
2506                 error2 = ext4_journal_stop(handle);
2507                 if (error == -ENOSPC &&
2508                     ext4_should_retry_alloc(sb, &retries))
2509                         goto retry;
2510                 if (error == 0)
2511                         error = error2;
2512         }
2513
2514         return error;
2515 }
2516
2517 /*
2518  * Shift the EA entries in the inode to create space for the increased
2519  * i_extra_isize.
2520  */
2521 static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
2522                                      int value_offs_shift, void *to,
2523                                      void *from, size_t n)
2524 {
2525         struct ext4_xattr_entry *last = entry;
2526         int new_offs;
2527
2528         /* We always shift xattr headers further thus offsets get lower */
2529         BUG_ON(value_offs_shift > 0);
2530
2531         /* Adjust the value offsets of the entries */
2532         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
2533                 if (!last->e_value_inum && last->e_value_size) {
2534                         new_offs = le16_to_cpu(last->e_value_offs) +
2535                                                         value_offs_shift;
2536                         last->e_value_offs = cpu_to_le16(new_offs);
2537                 }
2538         }
2539         /* Shift the entries by n bytes */
2540         memmove(to, from, n);
2541 }
2542
2543 /*
2544  * Move xattr pointed to by 'entry' from inode into external xattr block
2545  */
2546 static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode,
2547                                     struct ext4_inode *raw_inode,
2548                                     struct ext4_xattr_entry *entry)
2549 {
2550         struct ext4_xattr_ibody_find *is = NULL;
2551         struct ext4_xattr_block_find *bs = NULL;
2552         char *buffer = NULL, *b_entry_name = NULL;
2553         size_t value_size = le32_to_cpu(entry->e_value_size);
2554         struct ext4_xattr_info i = {
2555                 .value = NULL,
2556                 .value_len = 0,
2557                 .name_index = entry->e_name_index,
2558                 .in_inode = !!entry->e_value_inum,
2559         };
2560         struct ext4_xattr_ibody_header *header = IHDR(inode, raw_inode);
2561         int error;
2562
2563         is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
2564         bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
2565         buffer = kmalloc(value_size, GFP_NOFS);
2566         b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
2567         if (!is || !bs || !buffer || !b_entry_name) {
2568                 error = -ENOMEM;
2569                 goto out;
2570         }
2571
2572         is->s.not_found = -ENODATA;
2573         bs->s.not_found = -ENODATA;
2574         is->iloc.bh = NULL;
2575         bs->bh = NULL;
2576
2577         /* Save the entry name and the entry value */
2578         if (entry->e_value_inum) {
2579                 error = ext4_xattr_inode_get(inode, entry, buffer, value_size);
2580                 if (error)
2581                         goto out;
2582         } else {
2583                 size_t value_offs = le16_to_cpu(entry->e_value_offs);
2584                 memcpy(buffer, (void *)IFIRST(header) + value_offs, value_size);
2585         }
2586
2587         memcpy(b_entry_name, entry->e_name, entry->e_name_len);
2588         b_entry_name[entry->e_name_len] = '\0';
2589         i.name = b_entry_name;
2590
2591         error = ext4_get_inode_loc(inode, &is->iloc);
2592         if (error)
2593                 goto out;
2594
2595         error = ext4_xattr_ibody_find(inode, &i, is);
2596         if (error)
2597                 goto out;
2598
2599         /* Remove the chosen entry from the inode */
2600         error = ext4_xattr_ibody_set(handle, inode, &i, is);
2601         if (error)
2602                 goto out;
2603
2604         i.value = buffer;
2605         i.value_len = value_size;
2606         error = ext4_xattr_block_find(inode, &i, bs);
2607         if (error)
2608                 goto out;
2609
2610         /* Add entry which was removed from the inode into the block */
2611         error = ext4_xattr_block_set(handle, inode, &i, bs);
2612         if (error)
2613                 goto out;
2614         error = 0;
2615 out:
2616         kfree(b_entry_name);
2617         kfree(buffer);
2618         if (is)
2619                 brelse(is->iloc.bh);
2620         if (bs)
2621                 brelse(bs->bh);
2622         kfree(is);
2623         kfree(bs);
2624
2625         return error;
2626 }
2627
2628 static int ext4_xattr_make_inode_space(handle_t *handle, struct inode *inode,
2629                                        struct ext4_inode *raw_inode,
2630                                        int isize_diff, size_t ifree,
2631                                        size_t bfree, int *total_ino)
2632 {
2633         struct ext4_xattr_ibody_header *header = IHDR(inode, raw_inode);
2634         struct ext4_xattr_entry *small_entry;
2635         struct ext4_xattr_entry *entry;
2636         struct ext4_xattr_entry *last;
2637         unsigned int entry_size;        /* EA entry size */
2638         unsigned int total_size;        /* EA entry size + value size */
2639         unsigned int min_total_size;
2640         int error;
2641
2642         while (isize_diff > ifree) {
2643                 entry = NULL;
2644                 small_entry = NULL;
2645                 min_total_size = ~0U;
2646                 last = IFIRST(header);
2647                 /* Find the entry best suited to be pushed into EA block */
2648                 for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
2649                         /* never move system.data out of the inode */
2650                         if ((last->e_name_len == 4) &&
2651                             (last->e_name_index == EXT4_XATTR_INDEX_SYSTEM) &&
2652                             !memcmp(last->e_name, "data", 4))
2653                                 continue;
2654                         total_size = EXT4_XATTR_LEN(last->e_name_len);
2655                         if (!last->e_value_inum)
2656                                 total_size += EXT4_XATTR_SIZE(
2657                                                le32_to_cpu(last->e_value_size));
2658                         if (total_size <= bfree &&
2659                             total_size < min_total_size) {
2660                                 if (total_size + ifree < isize_diff) {
2661                                         small_entry = last;
2662                                 } else {
2663                                         entry = last;
2664                                         min_total_size = total_size;
2665                                 }
2666                         }
2667                 }
2668
2669                 if (entry == NULL) {
2670                         if (small_entry == NULL)
2671                                 return -ENOSPC;
2672                         entry = small_entry;
2673                 }
2674
2675                 entry_size = EXT4_XATTR_LEN(entry->e_name_len);
2676                 total_size = entry_size;
2677                 if (!entry->e_value_inum)
2678                         total_size += EXT4_XATTR_SIZE(
2679                                               le32_to_cpu(entry->e_value_size));
2680                 error = ext4_xattr_move_to_block(handle, inode, raw_inode,
2681                                                  entry);
2682                 if (error)
2683                         return error;
2684
2685                 *total_ino -= entry_size;
2686                 ifree += total_size;
2687                 bfree -= total_size;
2688         }
2689
2690         return 0;
2691 }
2692
2693 /*
2694  * Expand an inode by new_extra_isize bytes when EAs are present.
2695  * Returns 0 on success or negative error number on failure.
2696  */
2697 int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
2698                                struct ext4_inode *raw_inode, handle_t *handle)
2699 {
2700         struct ext4_xattr_ibody_header *header;
2701         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
2702         static unsigned int mnt_count;
2703         size_t min_offs;
2704         size_t ifree, bfree;
2705         int total_ino;
2706         void *base, *end;
2707         int error = 0, tried_min_extra_isize = 0;
2708         int s_min_extra_isize = le16_to_cpu(sbi->s_es->s_min_extra_isize);
2709         int isize_diff; /* How much do we need to grow i_extra_isize */
2710
2711 retry:
2712         isize_diff = new_extra_isize - EXT4_I(inode)->i_extra_isize;
2713         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
2714                 return 0;
2715
2716         header = IHDR(inode, raw_inode);
2717
2718         /*
2719          * Check if enough free space is available in the inode to shift the
2720          * entries ahead by new_extra_isize.
2721          */
2722
2723         base = IFIRST(header);
2724         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
2725         min_offs = end - base;
2726         total_ino = sizeof(struct ext4_xattr_ibody_header) + sizeof(u32);
2727
2728         error = xattr_check_inode(inode, header, end);
2729         if (error)
2730                 goto cleanup;
2731
2732         ifree = ext4_xattr_free_space(base, &min_offs, base, &total_ino);
2733         if (ifree >= isize_diff)
2734                 goto shift;
2735
2736         /*
2737          * Enough free space isn't available in the inode, check if
2738          * EA block can hold new_extra_isize bytes.
2739          */
2740         if (EXT4_I(inode)->i_file_acl) {
2741                 struct buffer_head *bh;
2742
2743                 bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
2744                 if (IS_ERR(bh)) {
2745                         error = PTR_ERR(bh);
2746                         goto cleanup;
2747                 }
2748                 error = ext4_xattr_check_block(inode, bh);
2749                 if (error) {
2750                         brelse(bh);
2751                         goto cleanup;
2752                 }
2753                 base = BHDR(bh);
2754                 end = bh->b_data + bh->b_size;
2755                 min_offs = end - base;
2756                 bfree = ext4_xattr_free_space(BFIRST(bh), &min_offs, base,
2757                                               NULL);
2758                 brelse(bh);
2759                 if (bfree + ifree < isize_diff) {
2760                         if (!tried_min_extra_isize && s_min_extra_isize) {
2761                                 tried_min_extra_isize++;
2762                                 new_extra_isize = s_min_extra_isize;
2763                                 goto retry;
2764                         }
2765                         error = -ENOSPC;
2766                         goto cleanup;
2767                 }
2768         } else {
2769                 bfree = inode->i_sb->s_blocksize;
2770         }
2771
2772         error = ext4_xattr_make_inode_space(handle, inode, raw_inode,
2773                                             isize_diff, ifree, bfree,
2774                                             &total_ino);
2775         if (error) {
2776                 if (error == -ENOSPC && !tried_min_extra_isize &&
2777                     s_min_extra_isize) {
2778                         tried_min_extra_isize++;
2779                         new_extra_isize = s_min_extra_isize;
2780                         goto retry;
2781                 }
2782                 goto cleanup;
2783         }
2784 shift:
2785         /* Adjust the offsets and shift the remaining entries ahead */
2786         ext4_xattr_shift_entries(IFIRST(header), EXT4_I(inode)->i_extra_isize
2787                         - new_extra_isize, (void *)raw_inode +
2788                         EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
2789                         (void *)header, total_ino);
2790         EXT4_I(inode)->i_extra_isize = new_extra_isize;
2791
2792 cleanup:
2793         if (error && (mnt_count != le16_to_cpu(sbi->s_es->s_mnt_count))) {
2794                 ext4_warning(inode->i_sb, "Unable to expand inode %lu. Delete some EAs or run e2fsck.",
2795                              inode->i_ino);
2796                 mnt_count = le16_to_cpu(sbi->s_es->s_mnt_count);
2797         }
2798         return error;
2799 }
2800
2801 #define EIA_INCR 16 /* must be 2^n */
2802 #define EIA_MASK (EIA_INCR - 1)
2803
2804 /* Add the large xattr @inode into @ea_inode_array for deferred iput().
2805  * If @ea_inode_array is new or full it will be grown and the old
2806  * contents copied over.
2807  */
2808 static int
2809 ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
2810                         struct inode *inode)
2811 {
2812         if (*ea_inode_array == NULL) {
2813                 /*
2814                  * Start with 15 inodes, so it fits into a power-of-two size.
2815                  * If *ea_inode_array is NULL, this is essentially offsetof()
2816                  */
2817                 (*ea_inode_array) =
2818                         kmalloc(offsetof(struct ext4_xattr_inode_array,
2819                                          inodes[EIA_MASK]),
2820                                 GFP_NOFS);
2821                 if (*ea_inode_array == NULL)
2822                         return -ENOMEM;
2823                 (*ea_inode_array)->count = 0;
2824         } else if (((*ea_inode_array)->count & EIA_MASK) == EIA_MASK) {
2825                 /* expand the array once all 15 + n * 16 slots are full */
2826                 struct ext4_xattr_inode_array *new_array = NULL;
2827                 int count = (*ea_inode_array)->count;
2828
2829                 /* if new_array is NULL, this is essentially offsetof() */
2830                 new_array = kmalloc(
2831                                 offsetof(struct ext4_xattr_inode_array,
2832                                          inodes[count + EIA_INCR]),
2833                                 GFP_NOFS);
2834                 if (new_array == NULL)
2835                         return -ENOMEM;
2836                 memcpy(new_array, *ea_inode_array,
2837                        offsetof(struct ext4_xattr_inode_array, inodes[count]));
2838                 kfree(*ea_inode_array);
2839                 *ea_inode_array = new_array;
2840         }
2841         (*ea_inode_array)->inodes[(*ea_inode_array)->count++] = inode;
2842         return 0;
2843 }
2844
2845 /*
2846  * ext4_xattr_delete_inode()
2847  *
2848  * Free extended attribute resources associated with this inode. Traverse
2849  * all entries and decrement reference on any xattr inodes associated with this
2850  * inode. This is called immediately before an inode is freed. We have exclusive
2851  * access to the inode. If an orphan inode is deleted it will also release its
2852  * references on xattr block and xattr inodes.
2853  */
2854 int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
2855                             struct ext4_xattr_inode_array **ea_inode_array,
2856                             int extra_credits)
2857 {
2858         struct buffer_head *bh = NULL;
2859         struct ext4_xattr_ibody_header *header;
2860         struct ext4_iloc iloc = { .bh = NULL };
2861         struct ext4_xattr_entry *entry;
2862         struct inode *ea_inode;
2863         int error;
2864
2865         error = ext4_xattr_ensure_credits(handle, inode, extra_credits,
2866                                           NULL /* bh */,
2867                                           false /* dirty */,
2868                                           false /* block_csum */);
2869         if (error) {
2870                 EXT4_ERROR_INODE(inode, "ensure credits (error %d)", error);
2871                 goto cleanup;
2872         }
2873
2874         if (ext4_has_feature_ea_inode(inode->i_sb) &&
2875             ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
2876
2877                 error = ext4_get_inode_loc(inode, &iloc);
2878                 if (error) {
2879                         EXT4_ERROR_INODE(inode, "inode loc (error %d)", error);
2880                         goto cleanup;
2881                 }
2882
2883                 error = ext4_journal_get_write_access(handle, iloc.bh);
2884                 if (error) {
2885                         EXT4_ERROR_INODE(inode, "write access (error %d)",
2886                                          error);
2887                         goto cleanup;
2888                 }
2889
2890                 header = IHDR(inode, ext4_raw_inode(&iloc));
2891                 if (header->h_magic == cpu_to_le32(EXT4_XATTR_MAGIC))
2892                         ext4_xattr_inode_dec_ref_all(handle, inode, iloc.bh,
2893                                                      IFIRST(header),
2894                                                      false /* block_csum */,
2895                                                      ea_inode_array,
2896                                                      extra_credits,
2897                                                      false /* skip_quota */);
2898         }
2899
2900         if (EXT4_I(inode)->i_file_acl) {
2901                 bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
2902                 if (IS_ERR(bh)) {
2903                         error = PTR_ERR(bh);
2904                         if (error == -EIO)
2905                                 EXT4_ERROR_INODE(inode, "block %llu read error",
2906                                                  EXT4_I(inode)->i_file_acl);
2907                         bh = NULL;
2908                         goto cleanup;
2909                 }
2910                 error = ext4_xattr_check_block(inode, bh);
2911                 if (error)
2912                         goto cleanup;
2913
2914                 if (ext4_has_feature_ea_inode(inode->i_sb)) {
2915                         for (entry = BFIRST(bh); !IS_LAST_ENTRY(entry);
2916                              entry = EXT4_XATTR_NEXT(entry)) {
2917                                 if (!entry->e_value_inum)
2918                                         continue;
2919                                 error = ext4_xattr_inode_iget(inode,
2920                                               le32_to_cpu(entry->e_value_inum),
2921                                               le32_to_cpu(entry->e_hash),
2922                                               &ea_inode);
2923                                 if (error)
2924                                         continue;
2925                                 ext4_xattr_inode_free_quota(inode, ea_inode,
2926                                               le32_to_cpu(entry->e_value_size));
2927                                 iput(ea_inode);
2928                         }
2929
2930                 }
2931
2932                 ext4_xattr_release_block(handle, inode, bh, ea_inode_array,
2933                                          extra_credits);
2934                 /*
2935                  * Update i_file_acl value in the same transaction that releases
2936                  * block.
2937                  */
2938                 EXT4_I(inode)->i_file_acl = 0;
2939                 error = ext4_mark_inode_dirty(handle, inode);
2940                 if (error) {
2941                         EXT4_ERROR_INODE(inode, "mark inode dirty (error %d)",
2942                                          error);
2943                         goto cleanup;
2944                 }
2945         }
2946         error = 0;
2947 cleanup:
2948         brelse(iloc.bh);
2949         brelse(bh);
2950         return error;
2951 }
2952
2953 void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *ea_inode_array)
2954 {
2955         int idx;
2956
2957         if (ea_inode_array == NULL)
2958                 return;
2959
2960         for (idx = 0; idx < ea_inode_array->count; ++idx)
2961                 iput(ea_inode_array->inodes[idx]);
2962         kfree(ea_inode_array);
2963 }
2964
2965 /*
2966  * ext4_xattr_block_cache_insert()
2967  *
2968  * Create a new entry in the extended attribute block cache, and insert
2969  * it unless such an entry is already in the cache.
2970  *
2971  * Returns 0, or a negative error number on failure.
2972  */
2973 static void
2974 ext4_xattr_block_cache_insert(struct mb_cache *ea_block_cache,
2975                               struct buffer_head *bh)
2976 {
2977         struct ext4_xattr_header *header = BHDR(bh);
2978         __u32 hash = le32_to_cpu(header->h_hash);
2979         int reusable = le32_to_cpu(header->h_refcount) <
2980                        EXT4_XATTR_REFCOUNT_MAX;
2981         int error;
2982
2983         if (!ea_block_cache)
2984                 return;
2985         error = mb_cache_entry_create(ea_block_cache, GFP_NOFS, hash,
2986                                       bh->b_blocknr, reusable);
2987         if (error) {
2988                 if (error == -EBUSY)
2989                         ea_bdebug(bh, "already in cache");
2990         } else
2991                 ea_bdebug(bh, "inserting [%x]", (int)hash);
2992 }
2993
2994 /*
2995  * ext4_xattr_cmp()
2996  *
2997  * Compare two extended attribute blocks for equality.
2998  *
2999  * Returns 0 if the blocks are equal, 1 if they differ, and
3000  * a negative error number on errors.
3001  */
3002 static int
3003 ext4_xattr_cmp(struct ext4_xattr_header *header1,
3004                struct ext4_xattr_header *header2)
3005 {
3006         struct ext4_xattr_entry *entry1, *entry2;
3007
3008         entry1 = ENTRY(header1+1);
3009         entry2 = ENTRY(header2+1);
3010         while (!IS_LAST_ENTRY(entry1)) {
3011                 if (IS_LAST_ENTRY(entry2))
3012                         return 1;
3013                 if (entry1->e_hash != entry2->e_hash ||
3014                     entry1->e_name_index != entry2->e_name_index ||
3015                     entry1->e_name_len != entry2->e_name_len ||
3016                     entry1->e_value_size != entry2->e_value_size ||
3017                     entry1->e_value_inum != entry2->e_value_inum ||
3018                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
3019                         return 1;
3020                 if (!entry1->e_value_inum &&
3021                     memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
3022                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
3023                            le32_to_cpu(entry1->e_value_size)))
3024                         return 1;
3025
3026                 entry1 = EXT4_XATTR_NEXT(entry1);
3027                 entry2 = EXT4_XATTR_NEXT(entry2);
3028         }
3029         if (!IS_LAST_ENTRY(entry2))
3030                 return 1;
3031         return 0;
3032 }
3033
3034 /*
3035  * ext4_xattr_block_cache_find()
3036  *
3037  * Find an identical extended attribute block.
3038  *
3039  * Returns a pointer to the block found, or NULL if such a block was
3040  * not found or an error occurred.
3041  */
3042 static struct buffer_head *
3043 ext4_xattr_block_cache_find(struct inode *inode,
3044                             struct ext4_xattr_header *header,
3045                             struct mb_cache_entry **pce)
3046 {
3047         __u32 hash = le32_to_cpu(header->h_hash);
3048         struct mb_cache_entry *ce;
3049         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
3050
3051         if (!ea_block_cache)
3052                 return NULL;
3053         if (!header->h_hash)
3054                 return NULL;  /* never share */
3055         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
3056         ce = mb_cache_entry_find_first(ea_block_cache, hash);
3057         while (ce) {
3058                 struct buffer_head *bh;
3059
3060                 bh = ext4_sb_bread(inode->i_sb, ce->e_value, REQ_PRIO);
3061                 if (IS_ERR(bh)) {
3062                         if (PTR_ERR(bh) == -ENOMEM)
3063                                 return NULL;
3064                         bh = NULL;
3065                         EXT4_ERROR_INODE(inode, "block %lu read error",
3066                                          (unsigned long)ce->e_value);
3067                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
3068                         *pce = ce;
3069                         return bh;
3070                 }
3071                 brelse(bh);
3072                 ce = mb_cache_entry_find_next(ea_block_cache, ce);
3073         }
3074         return NULL;
3075 }
3076
3077 #define NAME_HASH_SHIFT 5
3078 #define VALUE_HASH_SHIFT 16
3079
3080 /*
3081  * ext4_xattr_hash_entry()
3082  *
3083  * Compute the hash of an extended attribute.
3084  */
3085 static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value,
3086                                     size_t value_count)
3087 {
3088         __u32 hash = 0;
3089
3090         while (name_len--) {
3091                 hash = (hash << NAME_HASH_SHIFT) ^
3092                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
3093                        *name++;
3094         }
3095         while (value_count--) {
3096                 hash = (hash << VALUE_HASH_SHIFT) ^
3097                        (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
3098                        le32_to_cpu(*value++);
3099         }
3100         return cpu_to_le32(hash);
3101 }
3102
3103 #undef NAME_HASH_SHIFT
3104 #undef VALUE_HASH_SHIFT
3105
3106 #define BLOCK_HASH_SHIFT 16
3107
3108 /*
3109  * ext4_xattr_rehash()
3110  *
3111  * Re-compute the extended attribute hash value after an entry has changed.
3112  */
3113 static void ext4_xattr_rehash(struct ext4_xattr_header *header)
3114 {
3115         struct ext4_xattr_entry *here;
3116         __u32 hash = 0;
3117
3118         here = ENTRY(header+1);
3119         while (!IS_LAST_ENTRY(here)) {
3120                 if (!here->e_hash) {
3121                         /* Block is not shared if an entry's hash value == 0 */
3122                         hash = 0;
3123                         break;
3124                 }
3125                 hash = (hash << BLOCK_HASH_SHIFT) ^
3126                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
3127                        le32_to_cpu(here->e_hash);
3128                 here = EXT4_XATTR_NEXT(here);
3129         }
3130         header->h_hash = cpu_to_le32(hash);
3131 }
3132
3133 #undef BLOCK_HASH_SHIFT
3134
3135 #define HASH_BUCKET_BITS        10
3136
3137 struct mb_cache *
3138 ext4_xattr_create_cache(void)
3139 {
3140         return mb_cache_create(HASH_BUCKET_BITS);
3141 }
3142
3143 void ext4_xattr_destroy_cache(struct mb_cache *cache)
3144 {
3145         if (cache)
3146                 mb_cache_destroy(cache);
3147 }
3148