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, <agruen@suse.de>
   6  *
   7  * Fix by Harrison Xing <harrison@mountainviewdata.com>.
   8  * Ext4 code with a lot of help from Eric Jarman <ejarman@acm.org>.
   9  * Extended attributes for symlinks and special files added per
  10  *  suggestion of Luka Renko <luka.renko@hermes.si>.
  11  * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
  12  *  Red Hat Inc.
  13  * ea-in-inode support by Alex Tomas <alex@clusterfs.com> aka bzzz
  14  *  and Andreas Gruenbacher <agruen@suse.de>.
  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         [EXT4_XATTR_INDEX_HURD]              = &ext4_xattr_hurd_handler,
  97 };
  98
  99 const struct xattr_handler *ext4_xattr_handlers[] = {
 100         &ext4_xattr_user_handler,
 101         &ext4_xattr_trusted_handler,
 102 #ifdef CONFIG_EXT4_FS_POSIX_ACL
 103         &posix_acl_access_xattr_handler,
 104         &posix_acl_default_xattr_handler,
 105 #endif
 106 #ifdef CONFIG_EXT4_FS_SECURITY
 107         &ext4_xattr_security_handler,
 108 #endif
 109         &ext4_xattr_hurd_handler,
 110         NULL
 111 };
 112
 113 #define EA_BLOCK_CACHE(inode)   (((struct ext4_sb_info *) \
 114                                 inode->i_sb->s_fs_info)->s_ea_block_cache)
 115
 116 #define EA_INODE_CACHE(inode)   (((struct ext4_sb_info *) \
 117                                 inode->i_sb->s_fs_info)->s_ea_inode_cache)
 118
 119 static int
 120 ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
 121                         struct inode *inode);
 122
 123 #ifdef CONFIG_LOCKDEP
 124 void ext4_xattr_inode_set_class(struct inode *ea_inode)
 125 {
 126         lockdep_set_subclass(&ea_inode->i_rwsem, 1);
 127 }
 128 #endif
 129
 130 static __le32 ext4_xattr_block_csum(struct inode *inode,
 131                                     sector_t block_nr,
 132                                     struct ext4_xattr_header *hdr)
 133 {
 134         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 135         __u32 csum;
 136         __le64 dsk_block_nr = cpu_to_le64(block_nr);
 137         __u32 dummy_csum = 0;
 138         int offset = offsetof(struct ext4_xattr_header, h_checksum);
 139
 140         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&dsk_block_nr,
 141                            sizeof(dsk_block_nr));
 142         csum = ext4_chksum(sbi, csum, (__u8 *)hdr, offset);
 143         csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, sizeof(dummy_csum));
 144         offset += sizeof(dummy_csum);
 145         csum = ext4_chksum(sbi, csum, (__u8 *)hdr + offset,
 146                            EXT4_BLOCK_SIZE(inode->i_sb) - offset);
 147
 148         return cpu_to_le32(csum);
 149 }
 150
 151 static int ext4_xattr_block_csum_verify(struct inode *inode,
 152                                         struct buffer_head *bh)
 153 {
 154         struct ext4_xattr_header *hdr = BHDR(bh);
 155         int ret = 1;
 156
 157         if (ext4_has_metadata_csum(inode->i_sb)) {
 158                 lock_buffer(bh);
 159                 ret = (hdr->h_checksum == ext4_xattr_block_csum(inode,
 160                                                         bh->b_blocknr, hdr));
 161                 unlock_buffer(bh);
 162         }
 163         return ret;
 164 }
 165
 166 static void ext4_xattr_block_csum_set(struct inode *inode,
 167                                       struct buffer_head *bh)
 168 {
 169         if (ext4_has_metadata_csum(inode->i_sb))
 170                 BHDR(bh)->h_checksum = ext4_xattr_block_csum(inode,
 171                                                 bh->b_blocknr, BHDR(bh));
 172 }
 173
 174 static inline const struct xattr_handler *
 175 ext4_xattr_handler(int name_index)
 176 {
 177         const struct xattr_handler *handler = NULL;
 178
 179         if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
 180                 handler = ext4_xattr_handler_map[name_index];
 181         return handler;
 182 }
 183
 184 static int
 185 ext4_xattr_check_entries(struct ext4_xattr_entry *entry, void *end,
 186                          void *value_start)
 187 {
 188         struct ext4_xattr_entry *e = entry;
 189
 190         /* Find the end of the names list */
 191         while (!IS_LAST_ENTRY(e)) {
 192                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(e);
 193                 if ((void *)next >= end)
 194                         return -EFSCORRUPTED;
 195                 if (strnlen(e->e_name, e->e_name_len) != e->e_name_len)
 196                         return -EFSCORRUPTED;
 197                 e = next;
 198         }
 199
 200         /* Check the values */
 201         while (!IS_LAST_ENTRY(entry)) {
 202                 u32 size = le32_to_cpu(entry->e_value_size);
 203
 204                 if (size > EXT4_XATTR_SIZE_MAX)
 205                         return -EFSCORRUPTED;
 206
 207                 if (size != 0 && entry->e_value_inum == 0) {
 208                         u16 offs = le16_to_cpu(entry->e_value_offs);
 209                         void *value;
 210
 211                         /*
 212                          * The value cannot overlap the names, and the value
 213                          * with padding cannot extend beyond 'end'.  Check both
 214                          * the padded and unpadded sizes, since the size may
 215                          * overflow to 0 when adding padding.
 216                          */
 217                         if (offs > end - value_start)
 218                                 return -EFSCORRUPTED;
 219                         value = value_start + offs;
 220                         if (value < (void *)e + sizeof(u32) ||
 221                             size > end - value ||
 222                             EXT4_XATTR_SIZE(size) > end - value)
 223                                 return -EFSCORRUPTED;
 224                 }
 225                 entry = EXT4_XATTR_NEXT(entry);
 226         }
 227
 228         return 0;
 229 }
 230
 231 static inline int
 232 __ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh,
 233                          const char *function, unsigned int line)
 234 {
 235         int error = -EFSCORRUPTED;
 236
 237         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
 238             BHDR(bh)->h_blocks != cpu_to_le32(1))
 239                 goto errout;
 240         if (buffer_verified(bh))
 241                 return 0;
 242
 243         error = -EFSBADCRC;
 244         if (!ext4_xattr_block_csum_verify(inode, bh))
 245                 goto errout;
 246         error = ext4_xattr_check_entries(BFIRST(bh), bh->b_data + bh->b_size,
 247                                          bh->b_data);
 248 errout:
 249         if (error)
 250                 __ext4_error_inode(inode, function, line, 0, -error,
 251                                    "corrupted xattr block %llu",
 252                                    (unsigned long long) bh->b_blocknr);
 253         else
 254                 set_buffer_verified(bh);
 255         return error;
 256 }
 257
 258 #define ext4_xattr_check_block(inode, bh) \
 259         __ext4_xattr_check_block((inode), (bh),  __func__, __LINE__)
 260
 261
 262 static int
 263 __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
 264                          void *end, const char *function, unsigned int line)
 265 {
 266         int error = -EFSCORRUPTED;
 267
 268         if (end - (void *)header < sizeof(*header) + sizeof(u32) ||
 269             (header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)))
 270                 goto errout;
 271         error = ext4_xattr_check_entries(IFIRST(header), end, IFIRST(header));
 272 errout:
 273         if (error)
 274                 __ext4_error_inode(inode, function, line, 0, -error,
 275                                    "corrupted in-inode xattr");
 276         return error;
 277 }
 278
 279 #define xattr_check_inode(inode, header, end) \
 280         __xattr_check_inode((inode), (header), (end), __func__, __LINE__)
 281
 282 static int
 283 xattr_find_entry(struct inode *inode, struct ext4_xattr_entry **pentry,
 284                  void *end, int name_index, const char *name, int sorted)
 285 {
 286         struct ext4_xattr_entry *entry, *next;
 287         size_t name_len;
 288         int cmp = 1;
 289
 290         if (name == NULL)
 291                 return -EINVAL;
 292         name_len = strlen(name);
 293         for (entry = *pentry; !IS_LAST_ENTRY(entry); entry = next) {
 294                 next = EXT4_XATTR_NEXT(entry);
 295                 if ((void *) next >= end) {
 296                         EXT4_ERROR_INODE(inode, "corrupted xattr entries");
 297                         return -EFSCORRUPTED;
 298                 }
 299                 cmp = name_index - entry->e_name_index;
 300                 if (!cmp)
 301                         cmp = name_len - entry->e_name_len;
 302                 if (!cmp)
 303                         cmp = memcmp(name, entry->e_name, name_len);
 304                 if (cmp <= 0 && (sorted || cmp == 0))
 305                         break;
 306         }
 307         *pentry = entry;
 308         return cmp ? -ENODATA : 0;
 309 }
 310
 311 static u32
 312 ext4_xattr_inode_hash(struct ext4_sb_info *sbi, const void *buffer, size_t size)
 313 {
 314         return ext4_chksum(sbi, sbi->s_csum_seed, buffer, size);
 315 }
 316
 317 static u64 ext4_xattr_inode_get_ref(struct inode *ea_inode)
 318 {
 319         return ((u64)ea_inode->i_ctime.tv_sec << 32) |
 320                 (u32) inode_peek_iversion_raw(ea_inode);
 321 }
 322
 323 static void ext4_xattr_inode_set_ref(struct inode *ea_inode, u64 ref_count)
 324 {
 325         ea_inode->i_ctime.tv_sec = (u32)(ref_count >> 32);
 326         inode_set_iversion_raw(ea_inode, ref_count & 0xffffffff);
 327 }
 328
 329 static u32 ext4_xattr_inode_get_hash(struct inode *ea_inode)
 330 {
 331         return (u32)ea_inode->i_atime.tv_sec;
 332 }
 333
 334 static void ext4_xattr_inode_set_hash(struct inode *ea_inode, u32 hash)
 335 {
 336         ea_inode->i_atime.tv_sec = hash;
 337 }
 338
 339 /*
 340  * Read the EA value from an inode.
 341  */
 342 static int ext4_xattr_inode_read(struct inode *ea_inode, void *buf, size_t size)
 343 {
 344         int blocksize = 1 << ea_inode->i_blkbits;
 345         int bh_count = (size + blocksize - 1) >> ea_inode->i_blkbits;
 346         int tail_size = (size % blocksize) ?: blocksize;
 347         struct buffer_head *bhs_inline[8];
 348         struct buffer_head **bhs = bhs_inline;
 349         int i, ret;
 350
 351         if (bh_count > ARRAY_SIZE(bhs_inline)) {
 352                 bhs = kmalloc_array(bh_count, sizeof(*bhs), GFP_NOFS);
 353                 if (!bhs)
 354                         return -ENOMEM;
 355         }
 356
 357         ret = ext4_bread_batch(ea_inode, 0 /* block */, bh_count,
 358                                true /* wait */, bhs);
 359         if (ret)
 360                 goto free_bhs;
 361
 362         for (i = 0; i < bh_count; i++) {
 363                 /* There shouldn't be any holes in ea_inode. */
 364                 if (!bhs[i]) {
 365                         ret = -EFSCORRUPTED;
 366                         goto put_bhs;
 367                 }
 368                 memcpy((char *)buf + blocksize * i, bhs[i]->b_data,
 369                        i < bh_count - 1 ? blocksize : tail_size);
 370         }
 371         ret = 0;
 372 put_bhs:
 373         for (i = 0; i < bh_count; i++)
 374                 brelse(bhs[i]);
 375 free_bhs:
 376         if (bhs != bhs_inline)
 377                 kfree(bhs);
 378         return ret;
 379 }
 380
 381 #define EXT4_XATTR_INODE_GET_PARENT(inode) ((__u32)(inode)->i_mtime.tv_sec)
 382
 383 static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino,
 384                                  u32 ea_inode_hash, struct inode **ea_inode)
 385 {
 386         struct inode *inode;
 387         int err;
 388
 389         inode = ext4_iget(parent->i_sb, ea_ino, EXT4_IGET_NORMAL);
 390         if (IS_ERR(inode)) {
 391                 err = PTR_ERR(inode);
 392                 ext4_error(parent->i_sb,
 393                            "error while reading EA inode %lu err=%d", ea_ino,
 394                            err);
 395                 return err;
 396         }
 397
 398         if (is_bad_inode(inode)) {
 399                 ext4_error(parent->i_sb,
 400                            "error while reading EA inode %lu is_bad_inode",
 401                            ea_ino);
 402                 err = -EIO;
 403                 goto error;
 404         }
 405
 406         if (!(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)) {
 407                 ext4_error(parent->i_sb,
 408                            "EA inode %lu does not have EXT4_EA_INODE_FL flag",
 409                             ea_ino);
 410                 err = -EINVAL;
 411                 goto error;
 412         }
 413
 414         ext4_xattr_inode_set_class(inode);
 415
 416         /*
 417          * Check whether this is an old Lustre-style xattr inode. Lustre
 418          * implementation does not have hash validation, rather it has a
 419          * backpointer from ea_inode to the parent inode.
 420          */
 421         if (ea_inode_hash != ext4_xattr_inode_get_hash(inode) &&
 422             EXT4_XATTR_INODE_GET_PARENT(inode) == parent->i_ino &&
 423             inode->i_generation == parent->i_generation) {
 424                 ext4_set_inode_state(inode, EXT4_STATE_LUSTRE_EA_INODE);
 425                 ext4_xattr_inode_set_ref(inode, 1);
 426         } else {
 427                 inode_lock(inode);
 428                 inode->i_flags |= S_NOQUOTA;
 429                 inode_unlock(inode);
 430         }
 431
 432         *ea_inode = inode;
 433         return 0;
 434 error:
 435         iput(inode);
 436         return err;
 437 }
 438
 439 static int
 440 ext4_xattr_inode_verify_hashes(struct inode *ea_inode,
 441                                struct ext4_xattr_entry *entry, void *buffer,
 442                                size_t size)
 443 {
 444         u32 hash;
 445
 446         /* Verify stored hash matches calculated hash. */
 447         hash = ext4_xattr_inode_hash(EXT4_SB(ea_inode->i_sb), buffer, size);
 448         if (hash != ext4_xattr_inode_get_hash(ea_inode))
 449                 return -EFSCORRUPTED;
 450
 451         if (entry) {
 452                 __le32 e_hash, tmp_data;
 453
 454                 /* Verify entry hash. */
 455                 tmp_data = cpu_to_le32(hash);
 456                 e_hash = ext4_xattr_hash_entry(entry->e_name, entry->e_name_len,
 457                                                &tmp_data, 1);
 458                 if (e_hash != entry->e_hash)
 459                         return -EFSCORRUPTED;
 460         }
 461         return 0;
 462 }
 463
 464 /*
 465  * Read xattr value from the EA inode.
 466  */
 467 static int
 468 ext4_xattr_inode_get(struct inode *inode, struct ext4_xattr_entry *entry,
 469                      void *buffer, size_t size)
 470 {
 471         struct mb_cache *ea_inode_cache = EA_INODE_CACHE(inode);
 472         struct inode *ea_inode;
 473         int err;
 474
 475         err = ext4_xattr_inode_iget(inode, le32_to_cpu(entry->e_value_inum),
 476                                     le32_to_cpu(entry->e_hash), &ea_inode);
 477         if (err) {
 478                 ea_inode = NULL;
 479                 goto out;
 480         }
 481
 482         if (i_size_read(ea_inode) != size) {
 483                 ext4_warning_inode(ea_inode,
 484                                    "ea_inode file size=%llu entry size=%zu",
 485                                    i_size_read(ea_inode), size);
 486                 err = -EFSCORRUPTED;
 487                 goto out;
 488         }
 489
 490         err = ext4_xattr_inode_read(ea_inode, buffer, size);
 491         if (err)
 492                 goto out;
 493
 494         if (!ext4_test_inode_state(ea_inode, EXT4_STATE_LUSTRE_EA_INODE)) {
 495                 err = ext4_xattr_inode_verify_hashes(ea_inode, entry, buffer,
 496                                                      size);
 497                 if (err) {
 498                         ext4_warning_inode(ea_inode,
 499                                            "EA inode hash validation failed");
 500                         goto out;
 501                 }
 502
 503                 if (ea_inode_cache)
 504                         mb_cache_entry_create(ea_inode_cache, GFP_NOFS,
 505                                         ext4_xattr_inode_get_hash(ea_inode),
 506                                         ea_inode->i_ino, true /* reusable */);
 507         }
 508 out:
 509         iput(ea_inode);
 510         return err;
 511 }
 512
 513 static int
 514 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
 515                      void *buffer, size_t buffer_size)
 516 {
 517         struct buffer_head *bh = NULL;
 518         struct ext4_xattr_entry *entry;
 519         size_t size;
 520         void *end;
 521         int error;
 522         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
 523
 524         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 525                   name_index, name, buffer, (long)buffer_size);
 526
 527         if (!EXT4_I(inode)->i_file_acl)
 528                 return -ENODATA;
 529         ea_idebug(inode, "reading block %llu",
 530                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 531         bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
 532         if (IS_ERR(bh))
 533                 return PTR_ERR(bh);
 534         ea_bdebug(bh, "b_count=%d, refcount=%d",
 535                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 536         error = ext4_xattr_check_block(inode, bh);
 537         if (error)
 538                 goto cleanup;
 539         ext4_xattr_block_cache_insert(ea_block_cache, bh);
 540         entry = BFIRST(bh);
 541         end = bh->b_data + bh->b_size;
 542         error = xattr_find_entry(inode, &entry, end, name_index, name, 1);
 543         if (error)
 544                 goto cleanup;
 545         size = le32_to_cpu(entry->e_value_size);
 546         error = -ERANGE;
 547         if (unlikely(size > EXT4_XATTR_SIZE_MAX))
 548                 goto cleanup;
 549         if (buffer) {
 550                 if (size > buffer_size)
 551                         goto cleanup;
 552                 if (entry->e_value_inum) {
 553                         error = ext4_xattr_inode_get(inode, entry, buffer,
 554                                                      size);
 555                         if (error)
 556                                 goto cleanup;
 557                 } else {
 558                         u16 offset = le16_to_cpu(entry->e_value_offs);
 559                         void *p = bh->b_data + offset;
 560
 561                         if (unlikely(p + size > end))
 562                                 goto cleanup;
 563                         memcpy(buffer, p, size);
 564                 }
 565         }
 566         error = size;
 567
 568 cleanup:
 569         brelse(bh);
 570         return error;
 571 }
 572
 573 int
 574 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 575                      void *buffer, size_t buffer_size)
 576 {
 577         struct ext4_xattr_ibody_header *header;
 578         struct ext4_xattr_entry *entry;
 579         struct ext4_inode *raw_inode;
 580         struct ext4_iloc iloc;
 581         size_t size;
 582         void *end;
 583         int error;
 584
 585         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 586                 return -ENODATA;
 587         error = ext4_get_inode_loc(inode, &iloc);
 588         if (error)
 589                 return error;
 590         raw_inode = ext4_raw_inode(&iloc);
 591         header = IHDR(inode, raw_inode);
 592         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 593         error = xattr_check_inode(inode, header, end);
 594         if (error)
 595                 goto cleanup;
 596         entry = IFIRST(header);
 597         error = xattr_find_entry(inode, &entry, end, name_index, name, 0);
 598         if (error)
 599                 goto cleanup;
 600         size = le32_to_cpu(entry->e_value_size);
 601         error = -ERANGE;
 602         if (unlikely(size > EXT4_XATTR_SIZE_MAX))
 603                 goto cleanup;
 604         if (buffer) {
 605                 if (size > buffer_size)
 606                         goto cleanup;
 607                 if (entry->e_value_inum) {
 608                         error = ext4_xattr_inode_get(inode, entry, buffer,
 609                                                      size);
 610                         if (error)
 611                                 goto cleanup;
 612                 } else {
 613                         u16 offset = le16_to_cpu(entry->e_value_offs);
 614                         void *p = (void *)IFIRST(header) + offset;
 615
 616                         if (unlikely(p + size > end))
 617                                 goto cleanup;
 618                         memcpy(buffer, p, size);
 619                 }
 620         }
 621         error = size;
 622
 623 cleanup:
 624         brelse(iloc.bh);
 625         return error;
 626 }
 627
 628 /*
 629  * ext4_xattr_get()
 630  *
 631  * Copy an extended attribute into the buffer
 632  * provided, or compute the buffer size required.
 633  * Buffer is NULL to compute the size of the buffer required.
 634  *
 635  * Returns a negative error number on failure, or the number of bytes
 636  * used / required on success.
 637  */
 638 int
 639 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
 640                void *buffer, size_t buffer_size)
 641 {
 642         int error;
 643
 644         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 645                 return -EIO;
 646
 647         if (strlen(name) > 255)
 648                 return -ERANGE;
 649
 650         down_read(&EXT4_I(inode)->xattr_sem);
 651         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
 652                                      buffer_size);
 653         if (error == -ENODATA)
 654                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
 655                                              buffer_size);
 656         up_read(&EXT4_I(inode)->xattr_sem);
 657         return error;
 658 }
 659
 660 static int
 661 ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,
 662                         char *buffer, size_t buffer_size)
 663 {
 664         size_t rest = buffer_size;
 665
 666         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 667                 const struct xattr_handler *handler =
 668                         ext4_xattr_handler(entry->e_name_index);
 669
 670                 if (handler && (!handler->list || handler->list(dentry))) {
 671                         const char *prefix = handler->prefix ?: handler->name;
 672                         size_t prefix_len = strlen(prefix);
 673                         size_t size = prefix_len + entry->e_name_len + 1;
 674
 675                         if (buffer) {
 676                                 if (size > rest)
 677                                         return -ERANGE;
 678                                 memcpy(buffer, prefix, prefix_len);
 679                                 buffer += prefix_len;
 680                                 memcpy(buffer, entry->e_name, entry->e_name_len);
 681                                 buffer += entry->e_name_len;
 682                                 *buffer++ = 0;
 683                         }
 684                         rest -= size;
 685                 }
 686         }
 687         return buffer_size - rest;  /* total size */
 688 }
 689
 690 static int
 691 ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 692 {
 693         struct inode *inode = d_inode(dentry);
 694         struct buffer_head *bh = NULL;
 695         int error;
 696
 697         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 698                   buffer, (long)buffer_size);
 699
 700         if (!EXT4_I(inode)->i_file_acl)
 701                 return 0;
 702         ea_idebug(inode, "reading block %llu",
 703                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 704         bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
 705         if (IS_ERR(bh))
 706                 return PTR_ERR(bh);
 707         ea_bdebug(bh, "b_count=%d, refcount=%d",
 708                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 709         error = ext4_xattr_check_block(inode, bh);
 710         if (error)
 711                 goto cleanup;
 712         ext4_xattr_block_cache_insert(EA_BLOCK_CACHE(inode), bh);
 713         error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer,
 714                                         buffer_size);
 715 cleanup:
 716         brelse(bh);
 717         return error;
 718 }
 719
 720 static int
 721 ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 722 {
 723         struct inode *inode = d_inode(dentry);
 724         struct ext4_xattr_ibody_header *header;
 725         struct ext4_inode *raw_inode;
 726         struct ext4_iloc iloc;
 727         void *end;
 728         int error;
 729
 730         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 731                 return 0;
 732         error = ext4_get_inode_loc(inode, &iloc);
 733         if (error)
 734                 return error;
 735         raw_inode = ext4_raw_inode(&iloc);
 736         header = IHDR(inode, raw_inode);
 737         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 738         error = xattr_check_inode(inode, header, end);
 739         if (error)
 740                 goto cleanup;
 741         error = ext4_xattr_list_entries(dentry, IFIRST(header),
 742                                         buffer, buffer_size);
 743
 744 cleanup:
 745         brelse(iloc.bh);
 746         return error;
 747 }
 748
 749 /*
 750  * Inode operation listxattr()
 751  *
 752  * d_inode(dentry)->i_rwsem: don't care
 753  *
 754  * Copy a list of attribute names into the buffer
 755  * provided, or compute the buffer size required.
 756  * Buffer is NULL to compute the size of the buffer required.
 757  *
 758  * Returns a negative error number on failure, or the number of bytes
 759  * used / required on success.
 760  */
 761 ssize_t
 762 ext4_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 763 {
 764         int ret, ret2;
 765
 766         down_read(&EXT4_I(d_inode(dentry))->xattr_sem);
 767         ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size);
 768         if (ret < 0)
 769                 goto errout;
 770         if (buffer) {
 771                 buffer += ret;
 772                 buffer_size -= ret;
 773         }
 774         ret = ext4_xattr_block_list(dentry, buffer, buffer_size);
 775         if (ret < 0)
 776                 goto errout;
 777         ret += ret2;
 778 errout:
 779         up_read(&EXT4_I(d_inode(dentry))->xattr_sem);
 780         return ret;
 781 }
 782
 783 /*
 784  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 785  * not set, set it.
 786  */
 787 static void ext4_xattr_update_super_block(handle_t *handle,
 788                                           struct super_block *sb)
 789 {
 790         if (ext4_has_feature_xattr(sb))
 791                 return;
 792
 793         BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
 794         if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {
 795                 ext4_set_feature_xattr(sb);
 796                 ext4_handle_dirty_super(handle, sb);
 797         }
 798 }
 799
 800 int ext4_get_inode_usage(struct inode *inode, qsize_t *usage)
 801 {
 802         struct ext4_iloc iloc = { .bh = NULL };
 803         struct buffer_head *bh = NULL;
 804         struct ext4_inode *raw_inode;
 805         struct ext4_xattr_ibody_header *header;
 806         struct ext4_xattr_entry *entry;
 807         qsize_t ea_inode_refs = 0;
 808         void *end;
 809         int ret;
 810
 811         lockdep_assert_held_read(&EXT4_I(inode)->xattr_sem);
 812
 813         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
 814                 ret = ext4_get_inode_loc(inode, &iloc);
 815                 if (ret)
 816                         goto out;
 817                 raw_inode = ext4_raw_inode(&iloc);
 818                 header = IHDR(inode, raw_inode);
 819                 end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 820                 ret = xattr_check_inode(inode, header, end);
 821                 if (ret)
 822                         goto out;
 823
 824                 for (entry = IFIRST(header); !IS_LAST_ENTRY(entry);
 825                      entry = EXT4_XATTR_NEXT(entry))
 826                         if (entry->e_value_inum)
 827                                 ea_inode_refs++;
 828         }
 829
 830         if (EXT4_I(inode)->i_file_acl) {
 831                 bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
 832                 if (IS_ERR(bh)) {
 833                         ret = PTR_ERR(bh);
 834                         bh = NULL;
 835                         goto out;
 836                 }
 837
 838                 ret = ext4_xattr_check_block(inode, bh);
 839                 if (ret)
 840                         goto out;
 841
 842                 for (entry = BFIRST(bh); !IS_LAST_ENTRY(entry);
 843                      entry = EXT4_XATTR_NEXT(entry))
 844                         if (entry->e_value_inum)
 845                                 ea_inode_refs++;
 846         }
 847         *usage = ea_inode_refs + 1;
 848         ret = 0;
 849 out:
 850         brelse(iloc.bh);
 851         brelse(bh);
 852         return ret;
 853 }
 854
 855 static inline size_t round_up_cluster(struct inode *inode, size_t length)
 856 {
 857         struct super_block *sb = inode->i_sb;
 858         size_t cluster_size = 1 << (EXT4_SB(sb)->s_cluster_bits +
 859                                     inode->i_blkbits);
 860         size_t mask = ~(cluster_size - 1);
 861
 862         return (length + cluster_size - 1) & mask;
 863 }
 864
 865 static int ext4_xattr_inode_alloc_quota(struct inode *inode, size_t len)
 866 {
 867         int err;
 868
 869         err = dquot_alloc_inode(inode);
 870         if (err)
 871                 return err;
 872         err = dquot_alloc_space_nodirty(inode, round_up_cluster(inode, len));
 873         if (err)
 874                 dquot_free_inode(inode);
 875         return err;
 876 }
 877
 878 static void ext4_xattr_inode_free_quota(struct inode *parent,
 879                                         struct inode *ea_inode,
 880                                         size_t len)
 881 {
 882         if (ea_inode &&
 883             ext4_test_inode_state(ea_inode, EXT4_STATE_LUSTRE_EA_INODE))
 884                 return;
 885         dquot_free_space_nodirty(parent, round_up_cluster(parent, len));
 886         dquot_free_inode(parent);
 887 }
 888
 889 int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode,
 890                              struct buffer_head *block_bh, size_t value_len,
 891                              bool is_create)
 892 {
 893         int credits;
 894         int blocks;
 895
 896         /*
 897          * 1) Owner inode update
 898          * 2) Ref count update on old xattr block
 899          * 3) new xattr block
 900          * 4) block bitmap update for new xattr block
 901          * 5) group descriptor for new xattr block
 902          * 6) block bitmap update for old xattr block
 903          * 7) group descriptor for old block
 904          *
 905          * 6 & 7 can happen if we have two racing threads T_a and T_b
 906          * which are each trying to set an xattr on inodes I_a and I_b
 907          * which were both initially sharing an xattr block.
 908          */
 909         credits = 7;
 910
 911         /* Quota updates. */
 912         credits += EXT4_MAXQUOTAS_TRANS_BLOCKS(sb);
 913
 914         /*
 915          * In case of inline data, we may push out the data to a block,
 916          * so we need to reserve credits for this eventuality
 917          */
 918         if (inode && ext4_has_inline_data(inode))
 919                 credits += ext4_writepage_trans_blocks(inode) + 1;
 920
 921         /* We are done if ea_inode feature is not enabled. */
 922         if (!ext4_has_feature_ea_inode(sb))
 923                 return credits;
 924
 925         /* New ea_inode, inode map, block bitmap, group descriptor. */
 926         credits += 4;
 927
 928         /* Data blocks. */
 929         blocks = (value_len + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
 930
 931         /* Indirection block or one level of extent tree. */
 932         blocks += 1;
 933
 934         /* Block bitmap and group descriptor updates for each block. */
 935         credits += blocks * 2;
 936
 937         /* Blocks themselves. */
 938         credits += blocks;
 939
 940         if (!is_create) {
 941                 /* Dereference ea_inode holding old xattr value.
 942                  * Old ea_inode, inode map, block bitmap, group descriptor.
 943                  */
 944                 credits += 4;
 945
 946                 /* Data blocks for old ea_inode. */
 947                 blocks = XATTR_SIZE_MAX >> sb->s_blocksize_bits;
 948
 949                 /* Indirection block or one level of extent tree for old
 950                  * ea_inode.
 951                  */
 952                 blocks += 1;
 953
 954                 /* Block bitmap and group descriptor updates for each block. */
 955                 credits += blocks * 2;
 956         }
 957
 958         /* We may need to clone the existing xattr block in which case we need
 959          * to increment ref counts for existing ea_inodes referenced by it.
 960          */
 961         if (block_bh) {
 962                 struct ext4_xattr_entry *entry = BFIRST(block_bh);
 963
 964                 for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry))
 965                         if (entry->e_value_inum)
 966                                 /* Ref count update on ea_inode. */
 967                                 credits += 1;
 968         }
 969         return credits;
 970 }
 971
 972 static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode,
 973                                        int ref_change)
 974 {
 975         struct mb_cache *ea_inode_cache = EA_INODE_CACHE(ea_inode);
 976         struct ext4_iloc iloc;
 977         s64 ref_count;
 978         u32 hash;
 979         int ret;
 980
 981         inode_lock(ea_inode);
 982
 983         ret = ext4_reserve_inode_write(handle, ea_inode, &iloc);
 984         if (ret)
 985                 goto out;
 986
 987         ref_count = ext4_xattr_inode_get_ref(ea_inode);
 988         ref_count += ref_change;
 989         ext4_xattr_inode_set_ref(ea_inode, ref_count);
 990
 991         if (ref_change > 0) {
 992                 WARN_ONCE(ref_count <= 0, "EA inode %lu ref_count=%lld",
 993                           ea_inode->i_ino, ref_count);
 994
 995                 if (ref_count == 1) {
 996                         WARN_ONCE(ea_inode->i_nlink, "EA inode %lu i_nlink=%u",
 997                                   ea_inode->i_ino, ea_inode->i_nlink);
 998
 999                         set_nlink(ea_inode, 1);
1000                         ext4_orphan_del(handle, ea_inode);
1001
1002                         if (ea_inode_cache) {
1003                                 hash = ext4_xattr_inode_get_hash(ea_inode);
1004                                 mb_cache_entry_create(ea_inode_cache,
1005                                                       GFP_NOFS, hash,
1006                                                       ea_inode->i_ino,
1007                                                       true /* reusable */);
1008                         }
1009                 }
1010         } else {
1011                 WARN_ONCE(ref_count < 0, "EA inode %lu ref_count=%lld",
1012                           ea_inode->i_ino, ref_count);
1013
1014                 if (ref_count == 0) {
1015                         WARN_ONCE(ea_inode->i_nlink != 1,
1016                                   "EA inode %lu i_nlink=%u",
1017                                   ea_inode->i_ino, ea_inode->i_nlink);
1018
1019                         clear_nlink(ea_inode);
1020                         ext4_orphan_add(handle, ea_inode);
1021
1022                         if (ea_inode_cache) {
1023                                 hash = ext4_xattr_inode_get_hash(ea_inode);
1024                                 mb_cache_entry_delete(ea_inode_cache, hash,
1025                                                       ea_inode->i_ino);
1026                         }
1027                 }
1028         }
1029
1030         ret = ext4_mark_iloc_dirty(handle, ea_inode, &iloc);
1031         if (ret)
1032                 ext4_warning_inode(ea_inode,
1033                                    "ext4_mark_iloc_dirty() failed ret=%d", ret);
1034 out:
1035         inode_unlock(ea_inode);
1036         return ret;
1037 }
1038
1039 static int ext4_xattr_inode_inc_ref(handle_t *handle, struct inode *ea_inode)
1040 {
1041         return ext4_xattr_inode_update_ref(handle, ea_inode, 1);
1042 }
1043
1044 static int ext4_xattr_inode_dec_ref(handle_t *handle, struct inode *ea_inode)
1045 {
1046         return ext4_xattr_inode_update_ref(handle, ea_inode, -1);
1047 }
1048
1049 static int ext4_xattr_inode_inc_ref_all(handle_t *handle, struct inode *parent,
1050                                         struct ext4_xattr_entry *first)
1051 {
1052         struct inode *ea_inode;
1053         struct ext4_xattr_entry *entry;
1054         struct ext4_xattr_entry *failed_entry;
1055         unsigned int ea_ino;
1056         int err, saved_err;
1057
1058         for (entry = first; !IS_LAST_ENTRY(entry);
1059              entry = EXT4_XATTR_NEXT(entry)) {
1060                 if (!entry->e_value_inum)
1061                         continue;
1062                 ea_ino = le32_to_cpu(entry->e_value_inum);
1063                 err = ext4_xattr_inode_iget(parent, ea_ino,
1064                                             le32_to_cpu(entry->e_hash),
1065                                             &ea_inode);
1066                 if (err)
1067                         goto cleanup;
1068                 err = ext4_xattr_inode_inc_ref(handle, ea_inode);
1069                 if (err) {
1070                         ext4_warning_inode(ea_inode, "inc ref error %d", err);
1071                         iput(ea_inode);
1072                         goto cleanup;
1073                 }
1074                 iput(ea_inode);
1075         }
1076         return 0;
1077
1078 cleanup:
1079         saved_err = err;
1080         failed_entry = entry;
1081
1082         for (entry = first; entry != failed_entry;
1083              entry = EXT4_XATTR_NEXT(entry)) {
1084                 if (!entry->e_value_inum)
1085                         continue;
1086                 ea_ino = le32_to_cpu(entry->e_value_inum);
1087                 err = ext4_xattr_inode_iget(parent, ea_ino,
1088                                             le32_to_cpu(entry->e_hash),
1089                                             &ea_inode);
1090                 if (err) {
1091                         ext4_warning(parent->i_sb,
1092                                      "cleanup ea_ino %u iget error %d", ea_ino,
1093                                      err);
1094                         continue;
1095                 }
1096                 err = ext4_xattr_inode_dec_ref(handle, ea_inode);
1097                 if (err)
1098                         ext4_warning_inode(ea_inode, "cleanup dec ref error %d",
1099                                            err);
1100                 iput(ea_inode);
1101         }
1102         return saved_err;
1103 }
1104
1105 static int ext4_xattr_restart_fn(handle_t *handle, struct inode *inode,
1106                         struct buffer_head *bh, bool block_csum, bool dirty)
1107 {
1108         int error;
1109
1110         if (bh && dirty) {
1111                 if (block_csum)
1112                         ext4_xattr_block_csum_set(inode, bh);
1113                 error = ext4_handle_dirty_metadata(handle, NULL, bh);
1114                 if (error) {
1115                         ext4_warning(inode->i_sb, "Handle metadata (error %d)",
1116                                      error);
1117                         return error;
1118                 }
1119         }
1120         return 0;
1121 }
1122
1123 static void
1124 ext4_xattr_inode_dec_ref_all(handle_t *handle, struct inode *parent,
1125                              struct buffer_head *bh,
1126                              struct ext4_xattr_entry *first, bool block_csum,
1127                              struct ext4_xattr_inode_array **ea_inode_array,
1128                              int extra_credits, bool skip_quota)
1129 {
1130         struct inode *ea_inode;
1131         struct ext4_xattr_entry *entry;
1132         bool dirty = false;
1133         unsigned int ea_ino;
1134         int err;
1135         int credits;
1136
1137         /* One credit for dec ref on ea_inode, one for orphan list addition, */
1138         credits = 2 + extra_credits;
1139
1140         for (entry = first; !IS_LAST_ENTRY(entry);
1141              entry = EXT4_XATTR_NEXT(entry)) {
1142                 if (!entry->e_value_inum)
1143                         continue;
1144                 ea_ino = le32_to_cpu(entry->e_value_inum);
1145                 err = ext4_xattr_inode_iget(parent, ea_ino,
1146                                             le32_to_cpu(entry->e_hash),
1147                                             &ea_inode);
1148                 if (err)
1149                         continue;
1150
1151                 err = ext4_expand_inode_array(ea_inode_array, ea_inode);
1152                 if (err) {
1153                         ext4_warning_inode(ea_inode,
1154                                            "Expand inode array err=%d", err);
1155                         iput(ea_inode);
1156                         continue;
1157                 }
1158
1159                 err = ext4_journal_ensure_credits_fn(handle, credits, credits,
1160                         ext4_free_metadata_revoke_credits(parent->i_sb, 1),
1161                         ext4_xattr_restart_fn(handle, parent, bh, block_csum,
1162                                               dirty));
1163                 if (err < 0) {
1164                         ext4_warning_inode(ea_inode, "Ensure credits err=%d",
1165                                            err);
1166                         continue;
1167                 }
1168                 if (err > 0) {
1169                         err = ext4_journal_get_write_access(handle, bh);
1170                         if (err) {
1171                                 ext4_warning_inode(ea_inode,
1172                                                 "Re-get write access err=%d",
1173                                                 err);
1174                                 continue;
1175                         }
1176                 }
1177
1178                 err = ext4_xattr_inode_dec_ref(handle, ea_inode);
1179                 if (err) {
1180                         ext4_warning_inode(ea_inode, "ea_inode dec ref err=%d",
1181                                            err);
1182                         continue;
1183                 }
1184
1185                 if (!skip_quota)
1186                         ext4_xattr_inode_free_quota(parent, ea_inode,
1187                                               le32_to_cpu(entry->e_value_size));
1188
1189                 /*
1190                  * Forget about ea_inode within the same transaction that
1191                  * decrements the ref count. This avoids duplicate decrements in
1192                  * case the rest of the work spills over to subsequent
1193                  * transactions.
1194                  */
1195                 entry->e_value_inum = 0;
1196                 entry->e_value_size = 0;
1197
1198                 dirty = true;
1199         }
1200
1201         if (dirty) {
1202                 /*
1203                  * Note that we are deliberately skipping csum calculation for
1204                  * the final update because we do not expect any journal
1205                  * restarts until xattr block is freed.
1206                  */
1207
1208                 err = ext4_handle_dirty_metadata(handle, NULL, bh);
1209                 if (err)
1210                         ext4_warning_inode(parent,
1211                                            "handle dirty metadata err=%d", err);
1212         }
1213 }
1214
1215 /*
1216  * Release the xattr block BH: If the reference count is > 1, decrement it;
1217  * otherwise free the block.
1218  */
1219 static void
1220 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
1221                          struct buffer_head *bh,
1222                          struct ext4_xattr_inode_array **ea_inode_array,
1223                          int extra_credits)
1224 {
1225         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
1226         u32 hash, ref;
1227         int error = 0;
1228
1229         BUFFER_TRACE(bh, "get_write_access");
1230         error = ext4_journal_get_write_access(handle, bh);
1231         if (error)
1232                 goto out;
1233
1234         lock_buffer(bh);
1235         hash = le32_to_cpu(BHDR(bh)->h_hash);
1236         ref = le32_to_cpu(BHDR(bh)->h_refcount);
1237         if (ref == 1) {
1238                 ea_bdebug(bh, "refcount now=0; freeing");
1239                 /*
1240                  * This must happen under buffer lock for
1241                  * ext4_xattr_block_set() to reliably detect freed block
1242                  */
1243                 if (ea_block_cache)
1244                         mb_cache_entry_delete(ea_block_cache, hash,
1245                                               bh->b_blocknr);
1246                 get_bh(bh);
1247                 unlock_buffer(bh);
1248
1249                 if (ext4_has_feature_ea_inode(inode->i_sb))
1250                         ext4_xattr_inode_dec_ref_all(handle, inode, bh,
1251                                                      BFIRST(bh),
1252                                                      true /* block_csum */,
1253                                                      ea_inode_array,
1254                                                      extra_credits,
1255                                                      true /* skip_quota */);
1256                 ext4_free_blocks(handle, inode, bh, 0, 1,
1257                                  EXT4_FREE_BLOCKS_METADATA |
1258                                  EXT4_FREE_BLOCKS_FORGET);
1259         } else {
1260                 ref--;
1261                 BHDR(bh)->h_refcount = cpu_to_le32(ref);
1262                 if (ref == EXT4_XATTR_REFCOUNT_MAX - 1) {
1263                         struct mb_cache_entry *ce;
1264
1265                         if (ea_block_cache) {
1266                                 ce = mb_cache_entry_get(ea_block_cache, hash,
1267                                                         bh->b_blocknr);
1268                                 if (ce) {
1269                                         ce->e_reusable = 1;
1270                                         mb_cache_entry_put(ea_block_cache, ce);
1271                                 }
1272                         }
1273                 }
1274
1275                 ext4_xattr_block_csum_set(inode, bh);
1276                 /*
1277                  * Beware of this ugliness: Releasing of xattr block references
1278                  * from different inodes can race and so we have to protect
1279                  * from a race where someone else frees the block (and releases
1280                  * its journal_head) before we are done dirtying the buffer. In
1281                  * nojournal mode this race is harmless and we actually cannot
1282                  * call ext4_handle_dirty_metadata() with locked buffer as
1283                  * that function can call sync_dirty_buffer() so for that case
1284                  * we handle the dirtying after unlocking the buffer.
1285                  */
1286                 if (ext4_handle_valid(handle))
1287                         error = ext4_handle_dirty_metadata(handle, inode, bh);
1288                 unlock_buffer(bh);
1289                 if (!ext4_handle_valid(handle))
1290                         error = ext4_handle_dirty_metadata(handle, inode, bh);
1291                 if (IS_SYNC(inode))
1292                         ext4_handle_sync(handle);
1293                 dquot_free_block(inode, EXT4_C2B(EXT4_SB(inode->i_sb), 1));
1294                 ea_bdebug(bh, "refcount now=%d; releasing",
1295                           le32_to_cpu(BHDR(bh)->h_refcount));
1296         }
1297 out:
1298         ext4_std_error(inode->i_sb, error);
1299         return;
1300 }
1301
1302 /*
1303  * Find the available free space for EAs. This also returns the total number of
1304  * bytes used by EA entries.
1305  */
1306 static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
1307                                     size_t *min_offs, void *base, int *total)
1308 {
1309         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1310                 if (!last->e_value_inum && last->e_value_size) {
1311                         size_t offs = le16_to_cpu(last->e_value_offs);
1312                         if (offs < *min_offs)
1313                                 *min_offs = offs;
1314                 }
1315                 if (total)
1316                         *total += EXT4_XATTR_LEN(last->e_name_len);
1317         }
1318         return (*min_offs - ((void *)last - base) - sizeof(__u32));
1319 }
1320
1321 /*
1322  * Write the value of the EA in an inode.
1323  */
1324 static int ext4_xattr_inode_write(handle_t *handle, struct inode *ea_inode,
1325                                   const void *buf, int bufsize)
1326 {
1327         struct buffer_head *bh = NULL;
1328         unsigned long block = 0;
1329         int blocksize = ea_inode->i_sb->s_blocksize;
1330         int max_blocks = (bufsize + blocksize - 1) >> ea_inode->i_blkbits;
1331         int csize, wsize = 0;
1332         int ret = 0, ret2 = 0;
1333         int retries = 0;
1334
1335 retry:
1336         while (ret >= 0 && ret < max_blocks) {
1337                 struct ext4_map_blocks map;
1338                 map.m_lblk = block += ret;
1339                 map.m_len = max_blocks -= ret;
1340
1341                 ret = ext4_map_blocks(handle, ea_inode, &map,
1342                                       EXT4_GET_BLOCKS_CREATE);
1343                 if (ret <= 0) {
1344                         ext4_mark_inode_dirty(handle, ea_inode);
1345                         if (ret == -ENOSPC &&
1346                             ext4_should_retry_alloc(ea_inode->i_sb, &retries)) {
1347                                 ret = 0;
1348                                 goto retry;
1349                         }
1350                         break;
1351                 }
1352         }
1353
1354         if (ret < 0)
1355                 return ret;
1356
1357         block = 0;
1358         while (wsize < bufsize) {
1359                 brelse(bh);
1360                 csize = (bufsize - wsize) > blocksize ? blocksize :
1361                                                                 bufsize - wsize;
1362                 bh = ext4_getblk(handle, ea_inode, block, 0);
1363                 if (IS_ERR(bh))
1364                         return PTR_ERR(bh);
1365                 if (!bh) {
1366                         WARN_ON_ONCE(1);
1367                         EXT4_ERROR_INODE(ea_inode,
1368                                          "ext4_getblk() return bh = NULL");
1369                         return -EFSCORRUPTED;
1370                 }
1371                 ret = ext4_journal_get_write_access(handle, bh);
1372                 if (ret)
1373                         goto out;
1374
1375                 memcpy(bh->b_data, buf, csize);
1376                 set_buffer_uptodate(bh);
1377                 ext4_handle_dirty_metadata(handle, ea_inode, bh);
1378
1379                 buf += csize;
1380                 wsize += csize;
1381                 block += 1;
1382         }
1383
1384         inode_lock(ea_inode);
1385         i_size_write(ea_inode, wsize);
1386         ext4_update_i_disksize(ea_inode, wsize);
1387         inode_unlock(ea_inode);
1388
1389         ret2 = ext4_mark_inode_dirty(handle, ea_inode);
1390         if (unlikely(ret2 && !ret))
1391                 ret = ret2;
1392
1393 out:
1394         brelse(bh);
1395
1396         return ret;
1397 }
1398
1399 /*
1400  * Create an inode to store the value of a large EA.
1401  */
1402 static struct inode *ext4_xattr_inode_create(handle_t *handle,
1403                                              struct inode *inode, u32 hash)
1404 {
1405         struct inode *ea_inode = NULL;
1406         uid_t owner[2] = { i_uid_read(inode), i_gid_read(inode) };
1407         int err;
1408
1409         /*
1410          * Let the next inode be the goal, so we try and allocate the EA inode
1411          * in the same group, or nearby one.
1412          */
1413         ea_inode = ext4_new_inode(handle, inode->i_sb->s_root->d_inode,
1414                                   S_IFREG | 0600, NULL, inode->i_ino + 1, owner,
1415                                   EXT4_EA_INODE_FL);
1416         if (!IS_ERR(ea_inode)) {
1417                 ea_inode->i_op = &ext4_file_inode_operations;
1418                 ea_inode->i_fop = &ext4_file_operations;
1419                 ext4_set_aops(ea_inode);
1420                 ext4_xattr_inode_set_class(ea_inode);
1421                 unlock_new_inode(ea_inode);
1422                 ext4_xattr_inode_set_ref(ea_inode, 1);
1423                 ext4_xattr_inode_set_hash(ea_inode, hash);
1424                 err = ext4_mark_inode_dirty(handle, ea_inode);
1425                 if (!err)
1426                         err = ext4_inode_attach_jinode(ea_inode);
1427                 if (err) {
1428                         iput(ea_inode);
1429                         return ERR_PTR(err);
1430                 }
1431
1432                 /*
1433                  * Xattr inodes are shared therefore quota charging is performed
1434                  * at a higher level.
1435                  */
1436                 dquot_free_inode(ea_inode);
1437                 dquot_drop(ea_inode);
1438                 inode_lock(ea_inode);
1439                 ea_inode->i_flags |= S_NOQUOTA;
1440                 inode_unlock(ea_inode);
1441         }
1442
1443         return ea_inode;
1444 }
1445
1446 static struct inode *
1447 ext4_xattr_inode_cache_find(struct inode *inode, const void *value,
1448                             size_t value_len, u32 hash)
1449 {
1450         struct inode *ea_inode;
1451         struct mb_cache_entry *ce;
1452         struct mb_cache *ea_inode_cache = EA_INODE_CACHE(inode);
1453         void *ea_data;
1454
1455         if (!ea_inode_cache)
1456                 return NULL;
1457
1458         ce = mb_cache_entry_find_first(ea_inode_cache, hash);
1459         if (!ce)
1460                 return NULL;
1461
1462         ea_data = kvmalloc(value_len, GFP_KERNEL);
1463         if (!ea_data) {
1464                 mb_cache_entry_put(ea_inode_cache, ce);
1465                 return NULL;
1466         }
1467
1468         while (ce) {
1469                 ea_inode = ext4_iget(inode->i_sb, ce->e_value,
1470                                      EXT4_IGET_NORMAL);
1471                 if (!IS_ERR(ea_inode) &&
1472                     !is_bad_inode(ea_inode) &&
1473                     (EXT4_I(ea_inode)->i_flags & EXT4_EA_INODE_FL) &&
1474                     i_size_read(ea_inode) == value_len &&
1475                     !ext4_xattr_inode_read(ea_inode, ea_data, value_len) &&
1476                     !ext4_xattr_inode_verify_hashes(ea_inode, NULL, ea_data,
1477                                                     value_len) &&
1478                     !memcmp(value, ea_data, value_len)) {
1479                         mb_cache_entry_touch(ea_inode_cache, ce);
1480                         mb_cache_entry_put(ea_inode_cache, ce);
1481                         kvfree(ea_data);
1482                         return ea_inode;
1483                 }
1484
1485                 if (!IS_ERR(ea_inode))
1486                         iput(ea_inode);
1487                 ce = mb_cache_entry_find_next(ea_inode_cache, ce);
1488         }
1489         kvfree(ea_data);
1490         return NULL;
1491 }
1492
1493 /*
1494  * Add value of the EA in an inode.
1495  */
1496 static int ext4_xattr_inode_lookup_create(handle_t *handle, struct inode *inode,
1497                                           const void *value, size_t value_len,
1498                                           struct inode **ret_inode)
1499 {
1500         struct inode *ea_inode;
1501         u32 hash;
1502         int err;
1503
1504         hash = ext4_xattr_inode_hash(EXT4_SB(inode->i_sb), value, value_len);
1505         ea_inode = ext4_xattr_inode_cache_find(inode, value, value_len, hash);
1506         if (ea_inode) {
1507                 err = ext4_xattr_inode_inc_ref(handle, ea_inode);
1508                 if (err) {
1509                         iput(ea_inode);
1510                         return err;
1511                 }
1512
1513                 *ret_inode = ea_inode;
1514                 return 0;
1515         }
1516
1517         /* Create an inode for the EA value */
1518         ea_inode = ext4_xattr_inode_create(handle, inode, hash);
1519         if (IS_ERR(ea_inode))
1520                 return PTR_ERR(ea_inode);
1521
1522         err = ext4_xattr_inode_write(handle, ea_inode, value, value_len);
1523         if (err) {
1524                 ext4_xattr_inode_dec_ref(handle, ea_inode);
1525                 iput(ea_inode);
1526                 return err;
1527         }
1528
1529         if (EA_INODE_CACHE(inode))
1530                 mb_cache_entry_create(EA_INODE_CACHE(inode), GFP_NOFS, hash,
1531                                       ea_inode->i_ino, true /* reusable */);
1532
1533         *ret_inode = ea_inode;
1534         return 0;
1535 }
1536
1537 /*
1538  * Reserve min(block_size/8, 1024) bytes for xattr entries/names if ea_inode
1539  * feature is enabled.
1540  */
1541 #define EXT4_XATTR_BLOCK_RESERVE(inode) min(i_blocksize(inode)/8, 1024U)
1542
1543 static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
1544                                 struct ext4_xattr_search *s,
1545                                 handle_t *handle, struct inode *inode,
1546                                 bool is_block)
1547 {
1548         struct ext4_xattr_entry *last, *next;
1549         struct ext4_xattr_entry *here = s->here;
1550         size_t min_offs = s->end - s->base, name_len = strlen(i->name);
1551         int in_inode = i->in_inode;
1552         struct inode *old_ea_inode = NULL;
1553         struct inode *new_ea_inode = NULL;
1554         size_t old_size, new_size;
1555         int ret;
1556
1557         /* Space used by old and new values. */
1558         old_size = (!s->not_found && !here->e_value_inum) ?
1559                         EXT4_XATTR_SIZE(le32_to_cpu(here->e_value_size)) : 0;
1560         new_size = (i->value && !in_inode) ? EXT4_XATTR_SIZE(i->value_len) : 0;
1561
1562         /*
1563          * Optimization for the simple case when old and new values have the
1564          * same padded sizes. Not applicable if external inodes are involved.
1565          */
1566         if (new_size && new_size == old_size) {
1567                 size_t offs = le16_to_cpu(here->e_value_offs);
1568                 void *val = s->base + offs;
1569
1570                 here->e_value_size = cpu_to_le32(i->value_len);
1571                 if (i->value == EXT4_ZERO_XATTR_VALUE) {
1572                         memset(val, 0, new_size);
1573                 } else {
1574                         memcpy(val, i->value, i->value_len);
1575                         /* Clear padding bytes. */
1576                         memset(val + i->value_len, 0, new_size - i->value_len);
1577                 }
1578                 goto update_hash;
1579         }
1580
1581         /* Compute min_offs and last. */
1582         last = s->first;
1583         for (; !IS_LAST_ENTRY(last); last = next) {
1584                 next = EXT4_XATTR_NEXT(last);
1585                 if ((void *)next >= s->end) {
1586                         EXT4_ERROR_INODE(inode, "corrupted xattr entries");
1587                         ret = -EFSCORRUPTED;
1588                         goto out;
1589                 }
1590                 if (!last->e_value_inum && last->e_value_size) {
1591                         size_t offs = le16_to_cpu(last->e_value_offs);
1592                         if (offs < min_offs)
1593                                 min_offs = offs;
1594                 }
1595         }
1596
1597         /* Check whether we have enough space. */
1598         if (i->value) {
1599                 size_t free;
1600
1601                 free = min_offs - ((void *)last - s->base) - sizeof(__u32);
1602                 if (!s->not_found)
1603                         free += EXT4_XATTR_LEN(name_len) + old_size;
1604
1605                 if (free < EXT4_XATTR_LEN(name_len) + new_size) {
1606                         ret = -ENOSPC;
1607                         goto out;
1608                 }
1609
1610                 /*
1611                  * If storing the value in an external inode is an option,
1612                  * reserve space for xattr entries/names in the external
1613                  * attribute block so that a long value does not occupy the
1614                  * whole space and prevent futher entries being added.
1615                  */
1616                 if (ext4_has_feature_ea_inode(inode->i_sb) &&
1617                     new_size && is_block &&
1618                     (min_offs + old_size - new_size) <
1619                                         EXT4_XATTR_BLOCK_RESERVE(inode)) {
1620                         ret = -ENOSPC;
1621                         goto out;
1622                 }
1623         }
1624
1625         /*
1626          * Getting access to old and new ea inodes is subject to failures.
1627          * Finish that work before doing any modifications to the xattr data.
1628          */
1629         if (!s->not_found && here->e_value_inum) {
1630                 ret = ext4_xattr_inode_iget(inode,
1631                                             le32_to_cpu(here->e_value_inum),
1632                                             le32_to_cpu(here->e_hash),
1633                                             &old_ea_inode);
1634                 if (ret) {
1635                         old_ea_inode = NULL;
1636                         goto out;
1637                 }
1638         }
1639         if (i->value && in_inode) {
1640                 WARN_ON_ONCE(!i->value_len);
1641
1642                 ret = ext4_xattr_inode_alloc_quota(inode, i->value_len);
1643                 if (ret)
1644                         goto out;
1645
1646                 ret = ext4_xattr_inode_lookup_create(handle, inode, i->value,
1647                                                      i->value_len,
1648                                                      &new_ea_inode);
1649                 if (ret) {
1650                         new_ea_inode = NULL;
1651                         ext4_xattr_inode_free_quota(inode, NULL, i->value_len);
1652                         goto out;
1653                 }
1654         }
1655
1656         if (old_ea_inode) {
1657                 /* We are ready to release ref count on the old_ea_inode. */
1658                 ret = ext4_xattr_inode_dec_ref(handle, old_ea_inode);
1659                 if (ret) {
1660                         /* Release newly required ref count on new_ea_inode. */
1661                         if (new_ea_inode) {
1662                                 int err;
1663
1664                                 err = ext4_xattr_inode_dec_ref(handle,
1665                                                                new_ea_inode);
1666                                 if (err)
1667                                         ext4_warning_inode(new_ea_inode,
1668                                                   "dec ref new_ea_inode err=%d",
1669                                                   err);
1670                                 ext4_xattr_inode_free_quota(inode, new_ea_inode,
1671                                                             i->value_len);
1672                         }
1673                         goto out;
1674                 }
1675
1676                 ext4_xattr_inode_free_quota(inode, old_ea_inode,
1677                                             le32_to_cpu(here->e_value_size));
1678         }
1679
1680         /* No failures allowed past this point. */
1681
1682         if (!s->not_found && here->e_value_size && !here->e_value_inum) {
1683                 /* Remove the old value. */
1684                 void *first_val = s->base + min_offs;
1685                 size_t offs = le16_to_cpu(here->e_value_offs);
1686                 void *val = s->base + offs;
1687
1688                 memmove(first_val + old_size, first_val, val - first_val);
1689                 memset(first_val, 0, old_size);
1690                 min_offs += old_size;
1691
1692                 /* Adjust all value offsets. */
1693                 last = s->first;
1694                 while (!IS_LAST_ENTRY(last)) {
1695                         size_t o = le16_to_cpu(last->e_value_offs);
1696
1697                         if (!last->e_value_inum &&
1698                             last->e_value_size && o < offs)
1699                                 last->e_value_offs = cpu_to_le16(o + old_size);
1700                         last = EXT4_XATTR_NEXT(last);
1701                 }
1702         }
1703
1704         if (!i->value) {
1705                 /* Remove old name. */
1706                 size_t size = EXT4_XATTR_LEN(name_len);
1707
1708                 last = ENTRY((void *)last - size);
1709                 memmove(here, (void *)here + size,
1710                         (void *)last - (void *)here + sizeof(__u32));
1711                 memset(last, 0, size);
1712         } else if (s->not_found) {
1713                 /* Insert new name. */
1714                 size_t size = EXT4_XATTR_LEN(name_len);
1715                 size_t rest = (void *)last - (void *)here + sizeof(__u32);
1716
1717                 memmove((void *)here + size, here, rest);
1718                 memset(here, 0, size);
1719                 here->e_name_index = i->name_index;
1720                 here->e_name_len = name_len;
1721                 memcpy(here->e_name, i->name, name_len);
1722         } else {
1723                 /* This is an update, reset value info. */
1724                 here->e_value_inum = 0;
1725                 here->e_value_offs = 0;
1726                 here->e_value_size = 0;
1727         }
1728
1729         if (i->value) {
1730                 /* Insert new value. */
1731                 if (in_inode) {
1732                         here->e_value_inum = cpu_to_le32(new_ea_inode->i_ino);
1733                 } else if (i->value_len) {
1734                         void *val = s->base + min_offs - new_size;
1735
1736                         here->e_value_offs = cpu_to_le16(min_offs - new_size);
1737                         if (i->value == EXT4_ZERO_XATTR_VALUE) {
1738                                 memset(val, 0, new_size);
1739                         } else {
1740                                 memcpy(val, i->value, i->value_len);
1741                                 /* Clear padding bytes. */
1742                                 memset(val + i->value_len, 0,
1743                                        new_size - i->value_len);
1744                         }
1745                 }
1746                 here->e_value_size = cpu_to_le32(i->value_len);
1747         }
1748
1749 update_hash:
1750         if (i->value) {
1751                 __le32 hash = 0;
1752
1753                 /* Entry hash calculation. */
1754                 if (in_inode) {
1755                         __le32 crc32c_hash;
1756
1757                         /*
1758                          * Feed crc32c hash instead of the raw value for entry
1759                          * hash calculation. This is to avoid walking
1760                          * potentially long value buffer again.
1761                          */
1762                         crc32c_hash = cpu_to_le32(
1763                                        ext4_xattr_inode_get_hash(new_ea_inode));
1764                         hash = ext4_xattr_hash_entry(here->e_name,
1765                                                      here->e_name_len,
1766                                                      &crc32c_hash, 1);
1767                 } else if (is_block) {
1768                         __le32 *value = s->base + le16_to_cpu(
1769                                                         here->e_value_offs);
1770
1771                         hash = ext4_xattr_hash_entry(here->e_name,
1772                                                      here->e_name_len, value,
1773                                                      new_size >> 2);
1774                 }
1775                 here->e_hash = hash;
1776         }
1777
1778         if (is_block)
1779                 ext4_xattr_rehash((struct ext4_xattr_header *)s->base);
1780
1781         ret = 0;
1782 out:
1783         iput(old_ea_inode);
1784         iput(new_ea_inode);
1785         return ret;
1786 }
1787
1788 struct ext4_xattr_block_find {
1789         struct ext4_xattr_search s;
1790         struct buffer_head *bh;
1791 };
1792
1793 static int
1794 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
1795                       struct ext4_xattr_block_find *bs)
1796 {
1797         struct super_block *sb = inode->i_sb;
1798         int error;
1799
1800         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
1801                   i->name_index, i->name, i->value, (long)i->value_len);
1802
1803         if (EXT4_I(inode)->i_file_acl) {
1804                 /* The inode already has an extended attribute block. */
1805                 bs->bh = ext4_sb_bread(sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
1806                 if (IS_ERR(bs->bh)) {
1807                         error = PTR_ERR(bs->bh);
1808                         bs->bh = NULL;
1809                         return error;
1810                 }
1811                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
1812                         atomic_read(&(bs->bh->b_count)),
1813                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
1814                 error = ext4_xattr_check_block(inode, bs->bh);
1815                 if (error)
1816                         return error;
1817                 /* Find the named attribute. */
1818                 bs->s.base = BHDR(bs->bh);
1819                 bs->s.first = BFIRST(bs->bh);
1820                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
1821                 bs->s.here = bs->s.first;
1822                 error = xattr_find_entry(inode, &bs->s.here, bs->s.end,
1823                                          i->name_index, i->name, 1);
1824                 if (error && error != -ENODATA)
1825                         return error;
1826                 bs->s.not_found = error;
1827         }
1828         return 0;
1829 }
1830
1831 static int
1832 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
1833                      struct ext4_xattr_info *i,
1834                      struct ext4_xattr_block_find *bs)
1835 {
1836         struct super_block *sb = inode->i_sb;
1837         struct buffer_head *new_bh = NULL;
1838         struct ext4_xattr_search s_copy = bs->s;
1839         struct ext4_xattr_search *s = &s_copy;
1840         struct mb_cache_entry *ce = NULL;
1841         int error = 0;
1842         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
1843         struct inode *ea_inode = NULL, *tmp_inode;
1844         size_t old_ea_inode_quota = 0;
1845         unsigned int ea_ino;
1846
1847
1848 #define header(x) ((struct ext4_xattr_header *)(x))
1849
1850         if (s->base) {
1851                 BUFFER_TRACE(bs->bh, "get_write_access");
1852                 error = ext4_journal_get_write_access(handle, bs->bh);
1853                 if (error)
1854                         goto cleanup;
1855                 lock_buffer(bs->bh);
1856
1857                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
1858                         __u32 hash = le32_to_cpu(BHDR(bs->bh)->h_hash);
1859
1860                         /*
1861                          * This must happen under buffer lock for
1862                          * ext4_xattr_block_set() to reliably detect modified
1863                          * block
1864                          */
1865                         if (ea_block_cache)
1866                                 mb_cache_entry_delete(ea_block_cache, hash,
1867                                                       bs->bh->b_blocknr);
1868                         ea_bdebug(bs->bh, "modifying in-place");
1869                         error = ext4_xattr_set_entry(i, s, handle, inode,
1870                                                      true /* is_block */);
1871                         ext4_xattr_block_csum_set(inode, bs->bh);
1872                         unlock_buffer(bs->bh);
1873                         if (error == -EFSCORRUPTED)
1874                                 goto bad_block;
1875                         if (!error)
1876                                 error = ext4_handle_dirty_metadata(handle,
1877                                                                    inode,
1878                                                                    bs->bh);
1879                         if (error)
1880                                 goto cleanup;
1881                         goto inserted;
1882                 } else {
1883                         int offset = (char *)s->here - bs->bh->b_data;
1884
1885                         unlock_buffer(bs->bh);
1886                         ea_bdebug(bs->bh, "cloning");
1887                         s->base = kmalloc(bs->bh->b_size, GFP_NOFS);
1888                         error = -ENOMEM;
1889                         if (s->base == NULL)
1890                                 goto cleanup;
1891                         memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
1892                         s->first = ENTRY(header(s->base)+1);
1893                         header(s->base)->h_refcount = cpu_to_le32(1);
1894                         s->here = ENTRY(s->base + offset);
1895                         s->end = s->base + bs->bh->b_size;
1896
1897                         /*
1898                          * If existing entry points to an xattr inode, we need
1899                          * to prevent ext4_xattr_set_entry() from decrementing
1900                          * ref count on it because the reference belongs to the
1901                          * original block. In this case, make the entry look
1902                          * like it has an empty value.
1903                          */
1904                         if (!s->not_found && s->here->e_value_inum) {
1905                                 ea_ino = le32_to_cpu(s->here->e_value_inum);
1906                                 error = ext4_xattr_inode_iget(inode, ea_ino,
1907                                               le32_to_cpu(s->here->e_hash),
1908                                               &tmp_inode);
1909                                 if (error)
1910                                         goto cleanup;
1911
1912                                 if (!ext4_test_inode_state(tmp_inode,
1913                                                 EXT4_STATE_LUSTRE_EA_INODE)) {
1914                                         /*
1915                                          * Defer quota free call for previous
1916                                          * inode until success is guaranteed.
1917                                          */
1918                                         old_ea_inode_quota = le32_to_cpu(
1919                                                         s->here->e_value_size);
1920                                 }
1921                                 iput(tmp_inode);
1922
1923                                 s->here->e_value_inum = 0;
1924                                 s->here->e_value_size = 0;
1925                         }
1926                 }
1927         } else {
1928                 /* Allocate a buffer where we construct the new block. */
1929                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
1930                 /* assert(header == s->base) */
1931                 error = -ENOMEM;
1932                 if (s->base == NULL)
1933                         goto cleanup;
1934                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1935                 header(s->base)->h_blocks = cpu_to_le32(1);
1936                 header(s->base)->h_refcount = cpu_to_le32(1);
1937                 s->first = ENTRY(header(s->base)+1);
1938                 s->here = ENTRY(header(s->base)+1);
1939                 s->end = s->base + sb->s_blocksize;
1940         }
1941
1942         error = ext4_xattr_set_entry(i, s, handle, inode, true /* is_block */);
1943         if (error == -EFSCORRUPTED)
1944                 goto bad_block;
1945         if (error)
1946                 goto cleanup;
1947
1948         if (i->value && s->here->e_value_inum) {
1949                 /*
1950                  * A ref count on ea_inode has been taken as part of the call to
1951                  * ext4_xattr_set_entry() above. We would like to drop this
1952                  * extra ref but we have to wait until the xattr block is
1953                  * initialized and has its own ref count on the ea_inode.
1954                  */
1955                 ea_ino = le32_to_cpu(s->here->e_value_inum);
1956                 error = ext4_xattr_inode_iget(inode, ea_ino,
1957                                               le32_to_cpu(s->here->e_hash),
1958                                               &ea_inode);
1959                 if (error) {
1960                         ea_inode = NULL;
1961                         goto cleanup;
1962                 }
1963         }
1964
1965 inserted:
1966         if (!IS_LAST_ENTRY(s->first)) {
1967                 new_bh = ext4_xattr_block_cache_find(inode, header(s->base),
1968                                                      &ce);
1969                 if (new_bh) {
1970                         /* We found an identical block in the cache. */
1971                         if (new_bh == bs->bh)
1972                                 ea_bdebug(new_bh, "keeping");
1973                         else {
1974                                 u32 ref;
1975
1976                                 WARN_ON_ONCE(dquot_initialize_needed(inode));
1977
1978                                 /* The old block is released after updating
1979                                    the inode. */
1980                                 error = dquot_alloc_block(inode,
1981                                                 EXT4_C2B(EXT4_SB(sb), 1));
1982                                 if (error)
1983                                         goto cleanup;
1984                                 BUFFER_TRACE(new_bh, "get_write_access");
1985                                 error = ext4_journal_get_write_access(handle,
1986                                                                       new_bh);
1987                                 if (error)
1988                                         goto cleanup_dquot;
1989                                 lock_buffer(new_bh);
1990                                 /*
1991                                  * We have to be careful about races with
1992                                  * freeing, rehashing or adding references to
1993                                  * xattr block. Once we hold buffer lock xattr
1994                                  * block's state is stable so we can check
1995                                  * whether the block got freed / rehashed or
1996                                  * not.  Since we unhash mbcache entry under
1997                                  * buffer lock when freeing / rehashing xattr
1998                                  * block, checking whether entry is still
1999                                  * hashed is reliable. Same rules hold for
2000                                  * e_reusable handling.
2001                                  */
2002                                 if (hlist_bl_unhashed(&ce->e_hash_list) ||
2003                                     !ce->e_reusable) {
2004                                         /*
2005                                          * Undo everything and check mbcache
2006                                          * again.
2007                                          */
2008                                         unlock_buffer(new_bh);
2009                                         dquot_free_block(inode,
2010                                                          EXT4_C2B(EXT4_SB(sb),
2011                                                                   1));
2012                                         brelse(new_bh);
2013                                         mb_cache_entry_put(ea_block_cache, ce);
2014                                         ce = NULL;
2015                                         new_bh = NULL;
2016                                         goto inserted;
2017                                 }
2018                                 ref = le32_to_cpu(BHDR(new_bh)->h_refcount) + 1;
2019                                 BHDR(new_bh)->h_refcount = cpu_to_le32(ref);
2020                                 if (ref >= EXT4_XATTR_REFCOUNT_MAX)
2021                                         ce->e_reusable = 0;
2022                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
2023                                           ref);
2024                                 ext4_xattr_block_csum_set(inode, new_bh);
2025                                 unlock_buffer(new_bh);
2026                                 error = ext4_handle_dirty_metadata(handle,
2027                                                                    inode,
2028                                                                    new_bh);
2029                                 if (error)
2030                                         goto cleanup_dquot;
2031                         }
2032                         mb_cache_entry_touch(ea_block_cache, ce);
2033                         mb_cache_entry_put(ea_block_cache, ce);
2034                         ce = NULL;
2035                 } else if (bs->bh && s->base == bs->bh->b_data) {
2036                         /* We were modifying this block in-place. */
2037                         ea_bdebug(bs->bh, "keeping this block");
2038                         ext4_xattr_block_cache_insert(ea_block_cache, bs->bh);
2039                         new_bh = bs->bh;
2040                         get_bh(new_bh);
2041                 } else {
2042                         /* We need to allocate a new block */
2043                         ext4_fsblk_t goal, block;
2044
2045                         WARN_ON_ONCE(dquot_initialize_needed(inode));
2046
2047                         goal = ext4_group_first_block_no(sb,
2048                                                 EXT4_I(inode)->i_block_group);
2049
2050                         /* non-extent files can't have physical blocks past 2^32 */
2051                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
2052                                 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
2053
2054                         block = ext4_new_meta_blocks(handle, inode, goal, 0,
2055                                                      NULL, &error);
2056                         if (error)
2057                                 goto cleanup;
2058
2059                         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
2060                                 BUG_ON(block > EXT4_MAX_BLOCK_FILE_PHYS);
2061
2062                         ea_idebug(inode, "creating block %llu",
2063                                   (unsigned long long)block);
2064
2065                         new_bh = sb_getblk(sb, block);
2066                         if (unlikely(!new_bh)) {
2067                                 error = -ENOMEM;
2068 getblk_failed:
2069                                 ext4_free_blocks(handle, inode, NULL, block, 1,
2070                                                  EXT4_FREE_BLOCKS_METADATA);
2071                                 goto cleanup;
2072                         }
2073                         error = ext4_xattr_inode_inc_ref_all(handle, inode,
2074                                                       ENTRY(header(s->base)+1));
2075                         if (error)
2076                                 goto getblk_failed;
2077                         if (ea_inode) {
2078                                 /* Drop the extra ref on ea_inode. */
2079                                 error = ext4_xattr_inode_dec_ref(handle,
2080                                                                  ea_inode);
2081                                 if (error)
2082                                         ext4_warning_inode(ea_inode,
2083                                                            "dec ref error=%d",
2084                                                            error);
2085                                 iput(ea_inode);
2086                                 ea_inode = NULL;
2087                         }
2088
2089                         lock_buffer(new_bh);
2090                         error = ext4_journal_get_create_access(handle, new_bh);
2091                         if (error) {
2092                                 unlock_buffer(new_bh);
2093                                 error = -EIO;
2094                                 goto getblk_failed;
2095                         }
2096                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
2097                         ext4_xattr_block_csum_set(inode, new_bh);
2098                         set_buffer_uptodate(new_bh);
2099                         unlock_buffer(new_bh);
2100                         ext4_xattr_block_cache_insert(ea_block_cache, new_bh);
2101                         error = ext4_handle_dirty_metadata(handle, inode,
2102                                                            new_bh);
2103                         if (error)
2104                                 goto cleanup;
2105                 }
2106         }
2107
2108         if (old_ea_inode_quota)
2109                 ext4_xattr_inode_free_quota(inode, NULL, old_ea_inode_quota);
2110
2111         /* Update the inode. */
2112         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
2113
2114         /* Drop the previous xattr block. */
2115         if (bs->bh && bs->bh != new_bh) {
2116                 struct ext4_xattr_inode_array *ea_inode_array = NULL;
2117
2118                 ext4_xattr_release_block(handle, inode, bs->bh,
2119                                          &ea_inode_array,
2120                                          0 /* extra_credits */);
2121                 ext4_xattr_inode_array_free(ea_inode_array);
2122         }
2123         error = 0;
2124
2125 cleanup:
2126         if (ea_inode) {
2127                 int error2;
2128
2129                 error2 = ext4_xattr_inode_dec_ref(handle, ea_inode);
2130                 if (error2)
2131                         ext4_warning_inode(ea_inode, "dec ref error=%d",
2132                                            error2);
2133
2134                 /* If there was an error, revert the quota charge. */
2135                 if (error)
2136                         ext4_xattr_inode_free_quota(inode, ea_inode,
2137                                                     i_size_read(ea_inode));
2138                 iput(ea_inode);
2139         }
2140         if (ce)
2141                 mb_cache_entry_put(ea_block_cache, ce);
2142         brelse(new_bh);
2143         if (!(bs->bh && s->base == bs->bh->b_data))
2144                 kfree(s->base);
2145
2146         return error;
2147
2148 cleanup_dquot:
2149         dquot_free_block(inode, EXT4_C2B(EXT4_SB(sb), 1));
2150         goto cleanup;
2151
2152 bad_block:
2153         EXT4_ERROR_INODE(inode, "bad block %llu",
2154                          EXT4_I(inode)->i_file_acl);
2155         goto cleanup;
2156
2157 #undef header
2158 }
2159
2160 int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
2161                           struct ext4_xattr_ibody_find *is)
2162 {
2163         struct ext4_xattr_ibody_header *header;
2164         struct ext4_inode *raw_inode;
2165         int error;
2166
2167         if (EXT4_I(inode)->i_extra_isize == 0)
2168                 return 0;
2169         raw_inode = ext4_raw_inode(&is->iloc);
2170         header = IHDR(inode, raw_inode);
2171         is->s.base = is->s.first = IFIRST(header);
2172         is->s.here = is->s.first;
2173         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
2174         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
2175                 error = xattr_check_inode(inode, header, is->s.end);
2176                 if (error)
2177                         return error;
2178                 /* Find the named attribute. */
2179                 error = xattr_find_entry(inode, &is->s.here, is->s.end,
2180                                          i->name_index, i->name, 0);
2181                 if (error && error != -ENODATA)
2182                         return error;
2183                 is->s.not_found = error;
2184         }
2185         return 0;
2186 }
2187
2188 int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode,
2189                                 struct ext4_xattr_info *i,
2190                                 struct ext4_xattr_ibody_find *is)
2191 {
2192         struct ext4_xattr_ibody_header *header;
2193         struct ext4_xattr_search *s = &is->s;
2194         int error;
2195
2196         if (EXT4_I(inode)->i_extra_isize == 0)
2197                 return -ENOSPC;
2198         error = ext4_xattr_set_entry(i, s, handle, inode, false /* is_block */);
2199         if (error)
2200                 return error;
2201         header = IHDR(inode, ext4_raw_inode(&is->iloc));
2202         if (!IS_LAST_ENTRY(s->first)) {
2203                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
2204                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
2205         } else {
2206                 header->h_magic = cpu_to_le32(0);
2207                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
2208         }
2209         return 0;
2210 }
2211
2212 static int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
2213                                 struct ext4_xattr_info *i,
2214                                 struct ext4_xattr_ibody_find *is)
2215 {
2216         struct ext4_xattr_ibody_header *header;
2217         struct ext4_xattr_search *s = &is->s;
2218         int error;
2219
2220         if (EXT4_I(inode)->i_extra_isize == 0)
2221                 return -ENOSPC;
2222         error = ext4_xattr_set_entry(i, s, handle, inode, false /* is_block */);
2223         if (error)
2224                 return error;
2225         header = IHDR(inode, ext4_raw_inode(&is->iloc));
2226         if (!IS_LAST_ENTRY(s->first)) {
2227                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
2228                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
2229         } else {
2230                 header->h_magic = cpu_to_le32(0);
2231                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
2232         }
2233         return 0;
2234 }
2235
2236 static int ext4_xattr_value_same(struct ext4_xattr_search *s,
2237                                  struct ext4_xattr_info *i)
2238 {
2239         void *value;
2240
2241         /* When e_value_inum is set the value is stored externally. */
2242         if (s->here->e_value_inum)
2243                 return 0;
2244         if (le32_to_cpu(s->here->e_value_size) != i->value_len)
2245                 return 0;
2246         value = ((void *)s->base) + le16_to_cpu(s->here->e_value_offs);
2247         return !memcmp(value, i->value, i->value_len);
2248 }
2249
2250 static struct buffer_head *ext4_xattr_get_block(struct inode *inode)
2251 {
2252         struct buffer_head *bh;
2253         int error;
2254
2255         if (!EXT4_I(inode)->i_file_acl)
2256                 return NULL;
2257         bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
2258         if (IS_ERR(bh))
2259                 return bh;
2260         error = ext4_xattr_check_block(inode, bh);
2261         if (error) {
2262                 brelse(bh);
2263                 return ERR_PTR(error);
2264         }
2265         return bh;
2266 }
2267
2268 /*
2269  * ext4_xattr_set_handle()
2270  *
2271  * Create, replace or remove an extended attribute for this inode.  Value
2272  * is NULL to remove an existing extended attribute, and non-NULL to
2273  * either replace an existing extended attribute, or create a new extended
2274  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
2275  * specify that an extended attribute must exist and must not exist
2276  * previous to the call, respectively.
2277  *
2278  * Returns 0, or a negative error number on failure.
2279  */
2280 int
2281 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
2282                       const char *name, const void *value, size_t value_len,
2283                       int flags)
2284 {
2285         struct ext4_xattr_info i = {
2286                 .name_index = name_index,
2287                 .name = name,
2288                 .value = value,
2289                 .value_len = value_len,
2290                 .in_inode = 0,
2291         };
2292         struct ext4_xattr_ibody_find is = {
2293                 .s = { .not_found = -ENODATA, },
2294         };
2295         struct ext4_xattr_block_find bs = {
2296                 .s = { .not_found = -ENODATA, },
2297         };
2298         int no_expand;
2299         int error;
2300
2301         if (!name)
2302                 return -EINVAL;
2303         if (strlen(name) > 255)
2304                 return -ERANGE;
2305
2306         ext4_write_lock_xattr(inode, &no_expand);
2307
2308         /* Check journal credits under write lock. */
2309         if (ext4_handle_valid(handle)) {
2310                 struct buffer_head *bh;
2311                 int credits;
2312
2313                 bh = ext4_xattr_get_block(inode);
2314                 if (IS_ERR(bh)) {
2315                         error = PTR_ERR(bh);
2316                         goto cleanup;
2317                 }
2318
2319                 credits = __ext4_xattr_set_credits(inode->i_sb, inode, bh,
2320                                                    value_len,
2321                                                    flags & XATTR_CREATE);
2322                 brelse(bh);
2323
2324                 if (jbd2_handle_buffer_credits(handle) < credits) {
2325                         error = -ENOSPC;
2326                         goto cleanup;
2327                 }
2328         }
2329
2330         error = ext4_reserve_inode_write(handle, inode, &is.iloc);
2331         if (error)
2332                 goto cleanup;
2333
2334         if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) {
2335                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
2336                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
2337                 ext4_clear_inode_state(inode, EXT4_STATE_NEW);
2338         }
2339
2340         error = ext4_xattr_ibody_find(inode, &i, &is);
2341         if (error)
2342                 goto cleanup;
2343         if (is.s.not_found)
2344                 error = ext4_xattr_block_find(inode, &i, &bs);
2345         if (error)
2346                 goto cleanup;
2347         if (is.s.not_found && bs.s.not_found) {
2348                 error = -ENODATA;
2349                 if (flags & XATTR_REPLACE)
2350                         goto cleanup;
2351                 error = 0;
2352                 if (!value)
2353                         goto cleanup;
2354         } else {
2355                 error = -EEXIST;
2356                 if (flags & XATTR_CREATE)
2357                         goto cleanup;
2358         }
2359
2360         if (!value) {
2361                 if (!is.s.not_found)
2362                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
2363                 else if (!bs.s.not_found)
2364                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
2365         } else {
2366                 error = 0;
2367                 /* Xattr value did not change? Save us some work and bail out */
2368                 if (!is.s.not_found && ext4_xattr_value_same(&is.s, &i))
2369                         goto cleanup;
2370                 if (!bs.s.not_found && ext4_xattr_value_same(&bs.s, &i))
2371                         goto cleanup;
2372
2373                 if (ext4_has_feature_ea_inode(inode->i_sb) &&
2374                     (EXT4_XATTR_SIZE(i.value_len) >
2375                         EXT4_XATTR_MIN_LARGE_EA_SIZE(inode->i_sb->s_blocksize)))
2376                         i.in_inode = 1;
2377 retry_inode:
2378                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
2379                 if (!error && !bs.s.not_found) {
2380                         i.value = NULL;
2381                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
2382                 } else if (error == -ENOSPC) {
2383                         if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
2384                                 brelse(bs.bh);
2385                                 bs.bh = NULL;
2386                                 error = ext4_xattr_block_find(inode, &i, &bs);
2387                                 if (error)
2388                                         goto cleanup;
2389                         }
2390                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
2391                         if (!error && !is.s.not_found) {
2392                                 i.value = NULL;
2393                                 error = ext4_xattr_ibody_set(handle, inode, &i,
2394                                                              &is);
2395                         } else if (error == -ENOSPC) {
2396                                 /*
2397                                  * Xattr does not fit in the block, store at
2398                                  * external inode if possible.
2399                                  */
2400                                 if (ext4_has_feature_ea_inode(inode->i_sb) &&
2401                                     !i.in_inode) {
2402                                         i.in_inode = 1;
2403                                         goto retry_inode;
2404                                 }
2405                         }
2406                 }
2407         }
2408         if (!error) {
2409                 ext4_xattr_update_super_block(handle, inode->i_sb);
2410                 inode->i_ctime = current_time(inode);
2411                 if (!value)
2412                         no_expand = 0;
2413                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
2414                 /*
2415                  * The bh is consumed by ext4_mark_iloc_dirty, even with
2416                  * error != 0.
2417                  */
2418                 is.iloc.bh = NULL;
2419                 if (IS_SYNC(inode))
2420                         ext4_handle_sync(handle);
2421         }
2422         ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_XATTR);
2423
2424 cleanup:
2425         brelse(is.iloc.bh);
2426         brelse(bs.bh);
2427         ext4_write_unlock_xattr(inode, &no_expand);
2428         return error;
2429 }
2430
2431 int ext4_xattr_set_credits(struct inode *inode, size_t value_len,
2432                            bool is_create, int *credits)
2433 {
2434         struct buffer_head *bh;
2435         int err;
2436
2437         *credits = 0;
2438
2439         if (!EXT4_SB(inode->i_sb)->s_journal)
2440                 return 0;
2441
2442         down_read(&EXT4_I(inode)->xattr_sem);
2443
2444         bh = ext4_xattr_get_block(inode);
2445         if (IS_ERR(bh)) {
2446                 err = PTR_ERR(bh);
2447         } else {
2448                 *credits = __ext4_xattr_set_credits(inode->i_sb, inode, bh,
2449                                                     value_len, is_create);
2450                 brelse(bh);
2451                 err = 0;
2452         }
2453
2454         up_read(&EXT4_I(inode)->xattr_sem);
2455         return err;
2456 }
2457
2458 /*
2459  * ext4_xattr_set()
2460  *
2461  * Like ext4_xattr_set_handle, but start from an inode. This extended
2462  * attribute modification is a filesystem transaction by itself.
2463  *
2464  * Returns 0, or a negative error number on failure.
2465  */
2466 int
2467 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
2468                const void *value, size_t value_len, int flags)
2469 {
2470         handle_t *handle;
2471         struct super_block *sb = inode->i_sb;
2472         int error, retries = 0;
2473         int credits;
2474
2475         error = dquot_initialize(inode);
2476         if (error)
2477                 return error;
2478
2479 retry:
2480         error = ext4_xattr_set_credits(inode, value_len, flags & XATTR_CREATE,
2481                                        &credits);
2482         if (error)
2483                 return error;
2484
2485         handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
2486         if (IS_ERR(handle)) {
2487                 error = PTR_ERR(handle);
2488         } else {
2489                 int error2;
2490
2491                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
2492                                               value, value_len, flags);
2493                 error2 = ext4_journal_stop(handle);
2494                 if (error == -ENOSPC &&
2495                     ext4_should_retry_alloc(sb, &retries))
2496                         goto retry;
2497                 if (error == 0)
2498                         error = error2;
2499         }
2500         ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_XATTR);
2501
2502         return error;
2503 }
2504
2505 /*
2506  * Shift the EA entries in the inode to create space for the increased
2507  * i_extra_isize.
2508  */
2509 static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
2510                                      int value_offs_shift, void *to,
2511                                      void *from, size_t n)
2512 {
2513         struct ext4_xattr_entry *last = entry;
2514         int new_offs;
2515
2516         /* We always shift xattr headers further thus offsets get lower */
2517         BUG_ON(value_offs_shift > 0);
2518
2519         /* Adjust the value offsets of the entries */
2520         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
2521                 if (!last->e_value_inum && last->e_value_size) {
2522                         new_offs = le16_to_cpu(last->e_value_offs) +
2523                                                         value_offs_shift;
2524                         last->e_value_offs = cpu_to_le16(new_offs);
2525                 }
2526         }
2527         /* Shift the entries by n bytes */
2528         memmove(to, from, n);
2529 }
2530
2531 /*
2532  * Move xattr pointed to by 'entry' from inode into external xattr block
2533  */
2534 static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode,
2535                                     struct ext4_inode *raw_inode,
2536                                     struct ext4_xattr_entry *entry)
2537 {
2538         struct ext4_xattr_ibody_find *is = NULL;
2539         struct ext4_xattr_block_find *bs = NULL;
2540         char *buffer = NULL, *b_entry_name = NULL;
2541         size_t value_size = le32_to_cpu(entry->e_value_size);
2542         struct ext4_xattr_info i = {
2543                 .value = NULL,
2544                 .value_len = 0,
2545                 .name_index = entry->e_name_index,
2546                 .in_inode = !!entry->e_value_inum,
2547         };
2548         struct ext4_xattr_ibody_header *header = IHDR(inode, raw_inode);
2549         int error;
2550
2551         is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
2552         bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
2553         buffer = kmalloc(value_size, GFP_NOFS);
2554         b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
2555         if (!is || !bs || !buffer || !b_entry_name) {
2556                 error = -ENOMEM;
2557                 goto out;
2558         }
2559
2560         is->s.not_found = -ENODATA;
2561         bs->s.not_found = -ENODATA;
2562         is->iloc.bh = NULL;
2563         bs->bh = NULL;
2564
2565         /* Save the entry name and the entry value */
2566         if (entry->e_value_inum) {
2567                 error = ext4_xattr_inode_get(inode, entry, buffer, value_size);
2568                 if (error)
2569                         goto out;
2570         } else {
2571                 size_t value_offs = le16_to_cpu(entry->e_value_offs);
2572                 memcpy(buffer, (void *)IFIRST(header) + value_offs, value_size);
2573         }
2574
2575         memcpy(b_entry_name, entry->e_name, entry->e_name_len);
2576         b_entry_name[entry->e_name_len] = '\0';
2577         i.name = b_entry_name;
2578
2579         error = ext4_get_inode_loc(inode, &is->iloc);
2580         if (error)
2581                 goto out;
2582
2583         error = ext4_xattr_ibody_find(inode, &i, is);
2584         if (error)
2585                 goto out;
2586
2587         /* Remove the chosen entry from the inode */
2588         error = ext4_xattr_ibody_set(handle, inode, &i, is);
2589         if (error)
2590                 goto out;
2591
2592         i.value = buffer;
2593         i.value_len = value_size;
2594         error = ext4_xattr_block_find(inode, &i, bs);
2595         if (error)
2596                 goto out;
2597
2598         /* Add entry which was removed from the inode into the block */
2599         error = ext4_xattr_block_set(handle, inode, &i, bs);
2600         if (error)
2601                 goto out;
2602         error = 0;
2603 out:
2604         kfree(b_entry_name);
2605         kfree(buffer);
2606         if (is)
2607                 brelse(is->iloc.bh);
2608         if (bs)
2609                 brelse(bs->bh);
2610         kfree(is);
2611         kfree(bs);
2612
2613         return error;
2614 }
2615
2616 static int ext4_xattr_make_inode_space(handle_t *handle, struct inode *inode,
2617                                        struct ext4_inode *raw_inode,
2618                                        int isize_diff, size_t ifree,
2619                                        size_t bfree, int *total_ino)
2620 {
2621         struct ext4_xattr_ibody_header *header = IHDR(inode, raw_inode);
2622         struct ext4_xattr_entry *small_entry;
2623         struct ext4_xattr_entry *entry;
2624         struct ext4_xattr_entry *last;
2625         unsigned int entry_size;        /* EA entry size */
2626         unsigned int total_size;        /* EA entry size + value size */
2627         unsigned int min_total_size;
2628         int error;
2629
2630         while (isize_diff > ifree) {
2631                 entry = NULL;
2632                 small_entry = NULL;
2633                 min_total_size = ~0U;
2634                 last = IFIRST(header);
2635                 /* Find the entry best suited to be pushed into EA block */
2636                 for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
2637                         /* never move system.data out of the inode */
2638                         if ((last->e_name_len == 4) &&
2639                             (last->e_name_index == EXT4_XATTR_INDEX_SYSTEM) &&
2640                             !memcmp(last->e_name, "data", 4))
2641                                 continue;
2642                         total_size = EXT4_XATTR_LEN(last->e_name_len);
2643                         if (!last->e_value_inum)
2644                                 total_size += EXT4_XATTR_SIZE(
2645                                                le32_to_cpu(last->e_value_size));
2646                         if (total_size <= bfree &&
2647                             total_size < min_total_size) {
2648                                 if (total_size + ifree < isize_diff) {
2649                                         small_entry = last;
2650                                 } else {
2651                                         entry = last;
2652                                         min_total_size = total_size;
2653                                 }
2654                         }
2655                 }
2656
2657                 if (entry == NULL) {
2658                         if (small_entry == NULL)
2659                                 return -ENOSPC;
2660                         entry = small_entry;
2661                 }
2662
2663                 entry_size = EXT4_XATTR_LEN(entry->e_name_len);
2664                 total_size = entry_size;
2665                 if (!entry->e_value_inum)
2666                         total_size += EXT4_XATTR_SIZE(
2667                                               le32_to_cpu(entry->e_value_size));
2668                 error = ext4_xattr_move_to_block(handle, inode, raw_inode,
2669                                                  entry);
2670                 if (error)
2671                         return error;
2672
2673                 *total_ino -= entry_size;
2674                 ifree += total_size;
2675                 bfree -= total_size;
2676         }
2677
2678         return 0;
2679 }
2680
2681 /*
2682  * Expand an inode by new_extra_isize bytes when EAs are present.
2683  * Returns 0 on success or negative error number on failure.
2684  */
2685 int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
2686                                struct ext4_inode *raw_inode, handle_t *handle)
2687 {
2688         struct ext4_xattr_ibody_header *header;
2689         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
2690         static unsigned int mnt_count;
2691         size_t min_offs;
2692         size_t ifree, bfree;
2693         int total_ino;
2694         void *base, *end;
2695         int error = 0, tried_min_extra_isize = 0;
2696         int s_min_extra_isize = le16_to_cpu(sbi->s_es->s_min_extra_isize);
2697         int isize_diff; /* How much do we need to grow i_extra_isize */
2698
2699 retry:
2700         isize_diff = new_extra_isize - EXT4_I(inode)->i_extra_isize;
2701         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
2702                 return 0;
2703
2704         header = IHDR(inode, raw_inode);
2705
2706         /*
2707          * Check if enough free space is available in the inode to shift the
2708          * entries ahead by new_extra_isize.
2709          */
2710
2711         base = IFIRST(header);
2712         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
2713         min_offs = end - base;
2714         total_ino = sizeof(struct ext4_xattr_ibody_header) + sizeof(u32);
2715
2716         error = xattr_check_inode(inode, header, end);
2717         if (error)
2718                 goto cleanup;
2719
2720         ifree = ext4_xattr_free_space(base, &min_offs, base, &total_ino);
2721         if (ifree >= isize_diff)
2722                 goto shift;
2723
2724         /*
2725          * Enough free space isn't available in the inode, check if
2726          * EA block can hold new_extra_isize bytes.
2727          */
2728         if (EXT4_I(inode)->i_file_acl) {
2729                 struct buffer_head *bh;
2730
2731                 bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
2732                 if (IS_ERR(bh)) {
2733                         error = PTR_ERR(bh);
2734                         goto cleanup;
2735                 }
2736                 error = ext4_xattr_check_block(inode, bh);
2737                 if (error) {
2738                         brelse(bh);
2739                         goto cleanup;
2740                 }
2741                 base = BHDR(bh);
2742                 end = bh->b_data + bh->b_size;
2743                 min_offs = end - base;
2744                 bfree = ext4_xattr_free_space(BFIRST(bh), &min_offs, base,
2745                                               NULL);
2746                 brelse(bh);
2747                 if (bfree + ifree < isize_diff) {
2748                         if (!tried_min_extra_isize && s_min_extra_isize) {
2749                                 tried_min_extra_isize++;
2750                                 new_extra_isize = s_min_extra_isize;
2751                                 goto retry;
2752                         }
2753                         error = -ENOSPC;
2754                         goto cleanup;
2755                 }
2756         } else {
2757                 bfree = inode->i_sb->s_blocksize;
2758         }
2759
2760         error = ext4_xattr_make_inode_space(handle, inode, raw_inode,
2761                                             isize_diff, ifree, bfree,
2762                                             &total_ino);
2763         if (error) {
2764                 if (error == -ENOSPC && !tried_min_extra_isize &&
2765                     s_min_extra_isize) {
2766                         tried_min_extra_isize++;
2767                         new_extra_isize = s_min_extra_isize;
2768                         goto retry;
2769                 }
2770                 goto cleanup;
2771         }
2772 shift:
2773         /* Adjust the offsets and shift the remaining entries ahead */
2774         ext4_xattr_shift_entries(IFIRST(header), EXT4_I(inode)->i_extra_isize
2775                         - new_extra_isize, (void *)raw_inode +
2776                         EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
2777                         (void *)header, total_ino);
2778         EXT4_I(inode)->i_extra_isize = new_extra_isize;
2779
2780 cleanup:
2781         if (error && (mnt_count != le16_to_cpu(sbi->s_es->s_mnt_count))) {
2782                 ext4_warning(inode->i_sb, "Unable to expand inode %lu. Delete some EAs or run e2fsck.",
2783                              inode->i_ino);
2784                 mnt_count = le16_to_cpu(sbi->s_es->s_mnt_count);
2785         }
2786         return error;
2787 }
2788
2789 #define EIA_INCR 16 /* must be 2^n */
2790 #define EIA_MASK (EIA_INCR - 1)
2791
2792 /* Add the large xattr @inode into @ea_inode_array for deferred iput().
2793  * If @ea_inode_array is new or full it will be grown and the old
2794  * contents copied over.
2795  */
2796 static int
2797 ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
2798                         struct inode *inode)
2799 {
2800         if (*ea_inode_array == NULL) {
2801                 /*
2802                  * Start with 15 inodes, so it fits into a power-of-two size.
2803                  * If *ea_inode_array is NULL, this is essentially offsetof()
2804                  */
2805                 (*ea_inode_array) =
2806                         kmalloc(offsetof(struct ext4_xattr_inode_array,
2807                                          inodes[EIA_MASK]),
2808                                 GFP_NOFS);
2809                 if (*ea_inode_array == NULL)
2810                         return -ENOMEM;
2811                 (*ea_inode_array)->count = 0;
2812         } else if (((*ea_inode_array)->count & EIA_MASK) == EIA_MASK) {
2813                 /* expand the array once all 15 + n * 16 slots are full */
2814                 struct ext4_xattr_inode_array *new_array = NULL;
2815                 int count = (*ea_inode_array)->count;
2816
2817                 /* if new_array is NULL, this is essentially offsetof() */
2818                 new_array = kmalloc(
2819                                 offsetof(struct ext4_xattr_inode_array,
2820                                          inodes[count + EIA_INCR]),
2821                                 GFP_NOFS);
2822                 if (new_array == NULL)
2823                         return -ENOMEM;
2824                 memcpy(new_array, *ea_inode_array,
2825                        offsetof(struct ext4_xattr_inode_array, inodes[count]));
2826                 kfree(*ea_inode_array);
2827                 *ea_inode_array = new_array;
2828         }
2829         (*ea_inode_array)->inodes[(*ea_inode_array)->count++] = inode;
2830         return 0;
2831 }
2832
2833 /*
2834  * ext4_xattr_delete_inode()
2835  *
2836  * Free extended attribute resources associated with this inode. Traverse
2837  * all entries and decrement reference on any xattr inodes associated with this
2838  * inode. This is called immediately before an inode is freed. We have exclusive
2839  * access to the inode. If an orphan inode is deleted it will also release its
2840  * references on xattr block and xattr inodes.
2841  */
2842 int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
2843                             struct ext4_xattr_inode_array **ea_inode_array,
2844                             int extra_credits)
2845 {
2846         struct buffer_head *bh = NULL;
2847         struct ext4_xattr_ibody_header *header;
2848         struct ext4_iloc iloc = { .bh = NULL };
2849         struct ext4_xattr_entry *entry;
2850         struct inode *ea_inode;
2851         int error;
2852
2853         error = ext4_journal_ensure_credits(handle, extra_credits,
2854                         ext4_free_metadata_revoke_credits(inode->i_sb, 1));
2855         if (error < 0) {
2856                 EXT4_ERROR_INODE(inode, "ensure credits (error %d)", error);
2857                 goto cleanup;
2858         }
2859
2860         if (ext4_has_feature_ea_inode(inode->i_sb) &&
2861             ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
2862
2863                 error = ext4_get_inode_loc(inode, &iloc);
2864                 if (error) {
2865                         EXT4_ERROR_INODE(inode, "inode loc (error %d)", error);
2866                         goto cleanup;
2867                 }
2868
2869                 error = ext4_journal_get_write_access(handle, iloc.bh);
2870                 if (error) {
2871                         EXT4_ERROR_INODE(inode, "write access (error %d)",
2872                                          error);
2873                         goto cleanup;
2874                 }
2875
2876                 header = IHDR(inode, ext4_raw_inode(&iloc));
2877                 if (header->h_magic == cpu_to_le32(EXT4_XATTR_MAGIC))
2878                         ext4_xattr_inode_dec_ref_all(handle, inode, iloc.bh,
2879                                                      IFIRST(header),
2880                                                      false /* block_csum */,
2881                                                      ea_inode_array,
2882                                                      extra_credits,
2883                                                      false /* skip_quota */);
2884         }
2885
2886         if (EXT4_I(inode)->i_file_acl) {
2887                 bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
2888                 if (IS_ERR(bh)) {
2889                         error = PTR_ERR(bh);
2890                         if (error == -EIO) {
2891                                 EXT4_ERROR_INODE_ERR(inode, EIO,
2892                                                      "block %llu read error",
2893                                                      EXT4_I(inode)->i_file_acl);
2894                         }
2895                         bh = NULL;
2896                         goto cleanup;
2897                 }
2898                 error = ext4_xattr_check_block(inode, bh);
2899                 if (error)
2900                         goto cleanup;
2901
2902                 if (ext4_has_feature_ea_inode(inode->i_sb)) {
2903                         for (entry = BFIRST(bh); !IS_LAST_ENTRY(entry);
2904                              entry = EXT4_XATTR_NEXT(entry)) {
2905                                 if (!entry->e_value_inum)
2906                                         continue;
2907                                 error = ext4_xattr_inode_iget(inode,
2908                                               le32_to_cpu(entry->e_value_inum),
2909                                               le32_to_cpu(entry->e_hash),
2910                                               &ea_inode);
2911                                 if (error)
2912                                         continue;
2913                                 ext4_xattr_inode_free_quota(inode, ea_inode,
2914                                               le32_to_cpu(entry->e_value_size));
2915                                 iput(ea_inode);
2916                         }
2917
2918                 }
2919
2920                 ext4_xattr_release_block(handle, inode, bh, ea_inode_array,
2921                                          extra_credits);
2922                 /*
2923                  * Update i_file_acl value in the same transaction that releases
2924                  * block.
2925                  */
2926                 EXT4_I(inode)->i_file_acl = 0;
2927                 error = ext4_mark_inode_dirty(handle, inode);
2928                 if (error) {
2929                         EXT4_ERROR_INODE(inode, "mark inode dirty (error %d)",
2930                                          error);
2931                         goto cleanup;
2932                 }
2933                 ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_XATTR);
2934         }
2935         error = 0;
2936 cleanup:
2937         brelse(iloc.bh);
2938         brelse(bh);
2939         return error;
2940 }
2941
2942 void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *ea_inode_array)
2943 {
2944         int idx;
2945
2946         if (ea_inode_array == NULL)
2947                 return;
2948
2949         for (idx = 0; idx < ea_inode_array->count; ++idx)
2950                 iput(ea_inode_array->inodes[idx]);
2951         kfree(ea_inode_array);
2952 }
2953
2954 /*
2955  * ext4_xattr_block_cache_insert()
2956  *
2957  * Create a new entry in the extended attribute block cache, and insert
2958  * it unless such an entry is already in the cache.
2959  *
2960  * Returns 0, or a negative error number on failure.
2961  */
2962 static void
2963 ext4_xattr_block_cache_insert(struct mb_cache *ea_block_cache,
2964                               struct buffer_head *bh)
2965 {
2966         struct ext4_xattr_header *header = BHDR(bh);
2967         __u32 hash = le32_to_cpu(header->h_hash);
2968         int reusable = le32_to_cpu(header->h_refcount) <
2969                        EXT4_XATTR_REFCOUNT_MAX;
2970         int error;
2971
2972         if (!ea_block_cache)
2973                 return;
2974         error = mb_cache_entry_create(ea_block_cache, GFP_NOFS, hash,
2975                                       bh->b_blocknr, reusable);
2976         if (error) {
2977                 if (error == -EBUSY)
2978                         ea_bdebug(bh, "already in cache");
2979         } else
2980                 ea_bdebug(bh, "inserting [%x]", (int)hash);
2981 }
2982
2983 /*
2984  * ext4_xattr_cmp()
2985  *
2986  * Compare two extended attribute blocks for equality.
2987  *
2988  * Returns 0 if the blocks are equal, 1 if they differ, and
2989  * a negative error number on errors.
2990  */
2991 static int
2992 ext4_xattr_cmp(struct ext4_xattr_header *header1,
2993                struct ext4_xattr_header *header2)
2994 {
2995         struct ext4_xattr_entry *entry1, *entry2;
2996
2997         entry1 = ENTRY(header1+1);
2998         entry2 = ENTRY(header2+1);
2999         while (!IS_LAST_ENTRY(entry1)) {
3000                 if (IS_LAST_ENTRY(entry2))
3001                         return 1;
3002                 if (entry1->e_hash != entry2->e_hash ||
3003                     entry1->e_name_index != entry2->e_name_index ||
3004                     entry1->e_name_len != entry2->e_name_len ||
3005                     entry1->e_value_size != entry2->e_value_size ||
3006                     entry1->e_value_inum != entry2->e_value_inum ||
3007                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
3008                         return 1;
3009                 if (!entry1->e_value_inum &&
3010                     memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
3011                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
3012                            le32_to_cpu(entry1->e_value_size)))
3013                         return 1;
3014
3015                 entry1 = EXT4_XATTR_NEXT(entry1);
3016                 entry2 = EXT4_XATTR_NEXT(entry2);
3017         }
3018         if (!IS_LAST_ENTRY(entry2))
3019                 return 1;
3020         return 0;
3021 }
3022
3023 /*
3024  * ext4_xattr_block_cache_find()
3025  *
3026  * Find an identical extended attribute block.
3027  *
3028  * Returns a pointer to the block found, or NULL if such a block was
3029  * not found or an error occurred.
3030  */
3031 static struct buffer_head *
3032 ext4_xattr_block_cache_find(struct inode *inode,
3033                             struct ext4_xattr_header *header,
3034                             struct mb_cache_entry **pce)
3035 {
3036         __u32 hash = le32_to_cpu(header->h_hash);
3037         struct mb_cache_entry *ce;
3038         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
3039
3040         if (!ea_block_cache)
3041                 return NULL;
3042         if (!header->h_hash)
3043                 return NULL;  /* never share */
3044         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
3045         ce = mb_cache_entry_find_first(ea_block_cache, hash);
3046         while (ce) {
3047                 struct buffer_head *bh;
3048
3049                 bh = ext4_sb_bread(inode->i_sb, ce->e_value, REQ_PRIO);
3050                 if (IS_ERR(bh)) {
3051                         if (PTR_ERR(bh) == -ENOMEM)
3052                                 return NULL;
3053                         bh = NULL;
3054                         EXT4_ERROR_INODE(inode, "block %lu read error",
3055                                          (unsigned long)ce->e_value);
3056                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
3057                         *pce = ce;
3058                         return bh;
3059                 }
3060                 brelse(bh);
3061                 ce = mb_cache_entry_find_next(ea_block_cache, ce);
3062         }
3063         return NULL;
3064 }
3065
3066 #define NAME_HASH_SHIFT 5
3067 #define VALUE_HASH_SHIFT 16
3068
3069 /*
3070  * ext4_xattr_hash_entry()
3071  *
3072  * Compute the hash of an extended attribute.
3073  */
3074 static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value,
3075                                     size_t value_count)
3076 {
3077         __u32 hash = 0;
3078
3079         while (name_len--) {
3080                 hash = (hash << NAME_HASH_SHIFT) ^
3081                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
3082                        *name++;
3083         }
3084         while (value_count--) {
3085                 hash = (hash << VALUE_HASH_SHIFT) ^
3086                        (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
3087                        le32_to_cpu(*value++);
3088         }
3089         return cpu_to_le32(hash);
3090 }
3091
3092 #undef NAME_HASH_SHIFT
3093 #undef VALUE_HASH_SHIFT
3094
3095 #define BLOCK_HASH_SHIFT 16
3096
3097 /*
3098  * ext4_xattr_rehash()
3099  *
3100  * Re-compute the extended attribute hash value after an entry has changed.
3101  */
3102 static void ext4_xattr_rehash(struct ext4_xattr_header *header)
3103 {
3104         struct ext4_xattr_entry *here;
3105         __u32 hash = 0;
3106
3107         here = ENTRY(header+1);
3108         while (!IS_LAST_ENTRY(here)) {
3109                 if (!here->e_hash) {
3110                         /* Block is not shared if an entry's hash value == 0 */
3111                         hash = 0;
3112                         break;
3113                 }
3114                 hash = (hash << BLOCK_HASH_SHIFT) ^
3115                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
3116                        le32_to_cpu(here->e_hash);
3117                 here = EXT4_XATTR_NEXT(here);
3118         }
3119         header->h_hash = cpu_to_le32(hash);
3120 }
3121
3122 #undef BLOCK_HASH_SHIFT
3123
3124 #define HASH_BUCKET_BITS        10
3125
3126 struct mb_cache *
3127 ext4_xattr_create_cache(void)
3128 {
3129         return mb_cache_create(HASH_BUCKET_BITS);
3130 }
3131
3132 void ext4_xattr_destroy_cache(struct mb_cache *cache)
3133 {
3134         if (cache)
3135                 mb_cache_destroy(cache);
3136 }
3137