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 __le32 ext4_xattr_hash_entry_signed(char *name, size_t name_len, __le32 *value,
  85                                     size_t value_count);
  86 static void ext4_xattr_rehash(struct ext4_xattr_header *);
  87
  88 static const struct xattr_handler * const ext4_xattr_handler_map[] = {
  89         [EXT4_XATTR_INDEX_USER]              = &ext4_xattr_user_handler,
  90 #ifdef CONFIG_EXT4_FS_POSIX_ACL
  91         [EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &nop_posix_acl_access,
  92         [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &nop_posix_acl_default,
  93 #endif
  94         [EXT4_XATTR_INDEX_TRUSTED]           = &ext4_xattr_trusted_handler,
  95 #ifdef CONFIG_EXT4_FS_SECURITY
  96         [EXT4_XATTR_INDEX_SECURITY]          = &ext4_xattr_security_handler,
  97 #endif
  98         [EXT4_XATTR_INDEX_HURD]              = &ext4_xattr_hurd_handler,
  99 };
 100
 101 const struct xattr_handler * const ext4_xattr_handlers[] = {
 102         &ext4_xattr_user_handler,
 103         &ext4_xattr_trusted_handler,
 104 #ifdef CONFIG_EXT4_FS_SECURITY
 105         &ext4_xattr_security_handler,
 106 #endif
 107         &ext4_xattr_hurd_handler,
 108         NULL
 109 };
 110
 111 #define EA_BLOCK_CACHE(inode)   (((struct ext4_sb_info *) \
 112                                 inode->i_sb->s_fs_info)->s_ea_block_cache)
 113
 114 #define EA_INODE_CACHE(inode)   (((struct ext4_sb_info *) \
 115                                 inode->i_sb->s_fs_info)->s_ea_inode_cache)
 116
 117 static int
 118 ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
 119                         struct inode *inode);
 120
 121 #ifdef CONFIG_LOCKDEP
 122 void ext4_xattr_inode_set_class(struct inode *ea_inode)
 123 {
 124         struct ext4_inode_info *ei = EXT4_I(ea_inode);
 125
 126         lockdep_set_subclass(&ea_inode->i_rwsem, 1);
 127         (void) ei;      /* shut up clang warning if !CONFIG_LOCKDEP */
 128         lockdep_set_subclass(&ei->i_data_sem, I_DATA_SEM_EA);
 129 }
 130 #endif
 131
 132 static __le32 ext4_xattr_block_csum(struct inode *inode,
 133                                     sector_t block_nr,
 134                                     struct ext4_xattr_header *hdr)
 135 {
 136         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 137         __u32 csum;
 138         __le64 dsk_block_nr = cpu_to_le64(block_nr);
 139         __u32 dummy_csum = 0;
 140         int offset = offsetof(struct ext4_xattr_header, h_checksum);
 141
 142         csum = ext4_chksum(sbi->s_csum_seed, (__u8 *)&dsk_block_nr,
 143                            sizeof(dsk_block_nr));
 144         csum = ext4_chksum(csum, (__u8 *)hdr, offset);
 145         csum = ext4_chksum(csum, (__u8 *)&dummy_csum, sizeof(dummy_csum));
 146         offset += sizeof(dummy_csum);
 147         csum = ext4_chksum(csum, (__u8 *)hdr + offset,
 148                            EXT4_BLOCK_SIZE(inode->i_sb) - offset);
 149
 150         return cpu_to_le32(csum);
 151 }
 152
 153 static int ext4_xattr_block_csum_verify(struct inode *inode,
 154                                         struct buffer_head *bh)
 155 {
 156         struct ext4_xattr_header *hdr = BHDR(bh);
 157         int ret = 1;
 158
 159         if (ext4_has_feature_metadata_csum(inode->i_sb)) {
 160                 lock_buffer(bh);
 161                 ret = (hdr->h_checksum == ext4_xattr_block_csum(inode,
 162                                                         bh->b_blocknr, hdr));
 163                 unlock_buffer(bh);
 164         }
 165         return ret;
 166 }
 167
 168 static void ext4_xattr_block_csum_set(struct inode *inode,
 169                                       struct buffer_head *bh)
 170 {
 171         if (ext4_has_feature_metadata_csum(inode->i_sb))
 172                 BHDR(bh)->h_checksum = ext4_xattr_block_csum(inode,
 173                                                 bh->b_blocknr, BHDR(bh));
 174 }
 175
 176 static inline const char *ext4_xattr_prefix(int name_index,
 177                                             struct dentry *dentry)
 178 {
 179         const struct xattr_handler *handler = NULL;
 180
 181         if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
 182                 handler = ext4_xattr_handler_map[name_index];
 183
 184         if (!xattr_handler_can_list(handler, dentry))
 185                 return NULL;
 186
 187         return xattr_prefix(handler);
 188 }
 189
 190 static int
 191 check_xattrs(struct inode *inode, struct buffer_head *bh,
 192              struct ext4_xattr_entry *entry, void *end, void *value_start,
 193              const char *function, unsigned int line)
 194 {
 195         struct ext4_xattr_entry *e = entry;
 196         int err = -EFSCORRUPTED;
 197         char *err_str;
 198
 199         if (bh) {
 200                 if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
 201                     BHDR(bh)->h_blocks != cpu_to_le32(1)) {
 202                         err_str = "invalid header";
 203                         goto errout;
 204                 }
 205                 if (buffer_verified(bh))
 206                         return 0;
 207                 if (!ext4_xattr_block_csum_verify(inode, bh)) {
 208                         err = -EFSBADCRC;
 209                         err_str = "invalid checksum";
 210                         goto errout;
 211                 }
 212         } else {
 213                 struct ext4_xattr_ibody_header *header = value_start;
 214
 215                 header -= 1;
 216                 if (end - (void *)header < sizeof(*header) + sizeof(u32)) {
 217                         err_str = "in-inode xattr block too small";
 218                         goto errout;
 219                 }
 220                 if (header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)) {
 221                         err_str = "bad magic number in in-inode xattr";
 222                         goto errout;
 223                 }
 224         }
 225
 226         /* Find the end of the names list */
 227         while (!IS_LAST_ENTRY(e)) {
 228                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(e);
 229                 if ((void *)next >= end) {
 230                         err_str = "e_name out of bounds";
 231                         goto errout;
 232                 }
 233                 if (strnlen(e->e_name, e->e_name_len) != e->e_name_len) {
 234                         err_str = "bad e_name length";
 235                         goto errout;
 236                 }
 237                 e = next;
 238         }
 239
 240         /* Check the values */
 241         while (!IS_LAST_ENTRY(entry)) {
 242                 u32 size = le32_to_cpu(entry->e_value_size);
 243                 unsigned long ea_ino = le32_to_cpu(entry->e_value_inum);
 244
 245                 if (!ext4_has_feature_ea_inode(inode->i_sb) && ea_ino) {
 246                         err_str = "ea_inode specified without ea_inode feature enabled";
 247                         goto errout;
 248                 }
 249                 if (ea_ino && ((ea_ino == EXT4_ROOT_INO) ||
 250                                !ext4_valid_inum(inode->i_sb, ea_ino))) {
 251                         err_str = "invalid ea_ino";
 252                         goto errout;
 253                 }
 254                 if (size > EXT4_XATTR_SIZE_MAX) {
 255                         err_str = "e_value size too large";
 256                         goto errout;
 257                 }
 258
 259                 if (size != 0 && entry->e_value_inum == 0) {
 260                         u16 offs = le16_to_cpu(entry->e_value_offs);
 261                         void *value;
 262
 263                         /*
 264                          * The value cannot overlap the names, and the value
 265                          * with padding cannot extend beyond 'end'.  Check both
 266                          * the padded and unpadded sizes, since the size may
 267                          * overflow to 0 when adding padding.
 268                          */
 269                         if (offs > end - value_start) {
 270                                 err_str = "e_value out of bounds";
 271                                 goto errout;
 272                         }
 273                         value = value_start + offs;
 274                         if (value < (void *)e + sizeof(u32) ||
 275                             size > end - value ||
 276                             EXT4_XATTR_SIZE(size) > end - value) {
 277                                 err_str = "overlapping e_value ";
 278                                 goto errout;
 279                         }
 280                 }
 281                 entry = EXT4_XATTR_NEXT(entry);
 282         }
 283         if (bh)
 284                 set_buffer_verified(bh);
 285         return 0;
 286
 287 errout:
 288         if (bh)
 289                 __ext4_error_inode(inode, function, line, 0, -err,
 290                                    "corrupted xattr block %llu: %s",
 291                                    (unsigned long long) bh->b_blocknr,
 292                                    err_str);
 293         else
 294                 __ext4_error_inode(inode, function, line, 0, -err,
 295                                    "corrupted in-inode xattr: %s", err_str);
 296         return err;
 297 }
 298
 299 static inline int
 300 __ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh,
 301                          const char *function, unsigned int line)
 302 {
 303         return check_xattrs(inode, bh, BFIRST(bh), bh->b_data + bh->b_size,
 304                             bh->b_data, function, line);
 305 }
 306
 307 #define ext4_xattr_check_block(inode, bh) \
 308         __ext4_xattr_check_block((inode), (bh),  __func__, __LINE__)
 309
 310
 311 int
 312 __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
 313                          void *end, const char *function, unsigned int line)
 314 {
 315         return check_xattrs(inode, NULL, IFIRST(header), end, IFIRST(header),
 316                             function, line);
 317 }
 318
 319 static int
 320 xattr_find_entry(struct inode *inode, struct ext4_xattr_entry **pentry,
 321                  void *end, int name_index, const char *name, int sorted)
 322 {
 323         struct ext4_xattr_entry *entry, *next;
 324         size_t name_len;
 325         int cmp = 1;
 326
 327         if (name == NULL)
 328                 return -EINVAL;
 329         name_len = strlen(name);
 330         for (entry = *pentry; !IS_LAST_ENTRY(entry); entry = next) {
 331                 next = EXT4_XATTR_NEXT(entry);
 332                 if ((void *) next >= end) {
 333                         EXT4_ERROR_INODE(inode, "corrupted xattr entries");
 334                         return -EFSCORRUPTED;
 335                 }
 336                 cmp = name_index - entry->e_name_index;
 337                 if (!cmp)
 338                         cmp = name_len - entry->e_name_len;
 339                 if (!cmp)
 340                         cmp = memcmp(name, entry->e_name, name_len);
 341                 if (cmp <= 0 && (sorted || cmp == 0))
 342                         break;
 343         }
 344         *pentry = entry;
 345         return cmp ? -ENODATA : 0;
 346 }
 347
 348 static u32
 349 ext4_xattr_inode_hash(struct ext4_sb_info *sbi, const void *buffer, size_t size)
 350 {
 351         return ext4_chksum(sbi->s_csum_seed, buffer, size);
 352 }
 353
 354 static u64 ext4_xattr_inode_get_ref(struct inode *ea_inode)
 355 {
 356         return ((u64) inode_get_ctime_sec(ea_inode) << 32) |
 357                 (u32) inode_peek_iversion_raw(ea_inode);
 358 }
 359
 360 static void ext4_xattr_inode_set_ref(struct inode *ea_inode, u64 ref_count)
 361 {
 362         inode_set_ctime(ea_inode, (u32)(ref_count >> 32), 0);
 363         inode_set_iversion_raw(ea_inode, ref_count & 0xffffffff);
 364 }
 365
 366 static u32 ext4_xattr_inode_get_hash(struct inode *ea_inode)
 367 {
 368         return (u32) inode_get_atime_sec(ea_inode);
 369 }
 370
 371 static void ext4_xattr_inode_set_hash(struct inode *ea_inode, u32 hash)
 372 {
 373         inode_set_atime(ea_inode, hash, 0);
 374 }
 375
 376 /*
 377  * Read the EA value from an inode.
 378  */
 379 static int ext4_xattr_inode_read(struct inode *ea_inode, void *buf, size_t size)
 380 {
 381         int blocksize = 1 << ea_inode->i_blkbits;
 382         int bh_count = (size + blocksize - 1) >> ea_inode->i_blkbits;
 383         int tail_size = (size % blocksize) ?: blocksize;
 384         struct buffer_head *bhs_inline[8];
 385         struct buffer_head **bhs = bhs_inline;
 386         int i, ret;
 387
 388         if (bh_count > ARRAY_SIZE(bhs_inline)) {
 389                 bhs = kmalloc_array(bh_count, sizeof(*bhs), GFP_NOFS);
 390                 if (!bhs)
 391                         return -ENOMEM;
 392         }
 393
 394         ret = ext4_bread_batch(ea_inode, 0 /* block */, bh_count,
 395                                true /* wait */, bhs);
 396         if (ret)
 397                 goto free_bhs;
 398
 399         for (i = 0; i < bh_count; i++) {
 400                 /* There shouldn't be any holes in ea_inode. */
 401                 if (!bhs[i]) {
 402                         ret = -EFSCORRUPTED;
 403                         goto put_bhs;
 404                 }
 405                 memcpy((char *)buf + blocksize * i, bhs[i]->b_data,
 406                        i < bh_count - 1 ? blocksize : tail_size);
 407         }
 408         ret = 0;
 409 put_bhs:
 410         for (i = 0; i < bh_count; i++)
 411                 brelse(bhs[i]);
 412 free_bhs:
 413         if (bhs != bhs_inline)
 414                 kfree(bhs);
 415         return ret;
 416 }
 417
 418 #define EXT4_XATTR_INODE_GET_PARENT(inode) ((__u32)(inode_get_mtime_sec(inode)))
 419
 420 static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino,
 421                                  u32 ea_inode_hash, struct inode **ea_inode)
 422 {
 423         struct inode *inode;
 424         int err;
 425
 426         /*
 427          * We have to check for this corruption early as otherwise
 428          * iget_locked() could wait indefinitely for the state of our
 429          * parent inode.
 430          */
 431         if (parent->i_ino == ea_ino) {
 432                 ext4_error(parent->i_sb,
 433                            "Parent and EA inode have the same ino %lu", ea_ino);
 434                 return -EFSCORRUPTED;
 435         }
 436
 437         inode = ext4_iget(parent->i_sb, ea_ino, EXT4_IGET_EA_INODE);
 438         if (IS_ERR(inode)) {
 439                 err = PTR_ERR(inode);
 440                 ext4_error(parent->i_sb,
 441                            "error while reading EA inode %lu err=%d", ea_ino,
 442                            err);
 443                 return err;
 444         }
 445         ext4_xattr_inode_set_class(inode);
 446
 447         /*
 448          * Check whether this is an old Lustre-style xattr inode. Lustre
 449          * implementation does not have hash validation, rather it has a
 450          * backpointer from ea_inode to the parent inode.
 451          */
 452         if (ea_inode_hash != ext4_xattr_inode_get_hash(inode) &&
 453             EXT4_XATTR_INODE_GET_PARENT(inode) == parent->i_ino &&
 454             inode->i_generation == parent->i_generation) {
 455                 ext4_set_inode_state(inode, EXT4_STATE_LUSTRE_EA_INODE);
 456                 ext4_xattr_inode_set_ref(inode, 1);
 457         } else {
 458                 inode_lock_nested(inode, I_MUTEX_XATTR);
 459                 inode->i_flags |= S_NOQUOTA;
 460                 inode_unlock(inode);
 461         }
 462
 463         *ea_inode = inode;
 464         return 0;
 465 }
 466
 467 /* Remove entry from mbcache when EA inode is getting evicted */
 468 void ext4_evict_ea_inode(struct inode *inode)
 469 {
 470         struct mb_cache_entry *oe;
 471
 472         if (!EA_INODE_CACHE(inode))
 473                 return;
 474         /* Wait for entry to get unused so that we can remove it */
 475         while ((oe = mb_cache_entry_delete_or_get(EA_INODE_CACHE(inode),
 476                         ext4_xattr_inode_get_hash(inode), inode->i_ino))) {
 477                 mb_cache_entry_wait_unused(oe);
 478                 mb_cache_entry_put(EA_INODE_CACHE(inode), oe);
 479         }
 480 }
 481
 482 static int
 483 ext4_xattr_inode_verify_hashes(struct inode *ea_inode,
 484                                struct ext4_xattr_entry *entry, void *buffer,
 485                                size_t size)
 486 {
 487         u32 hash;
 488
 489         /* Verify stored hash matches calculated hash. */
 490         hash = ext4_xattr_inode_hash(EXT4_SB(ea_inode->i_sb), buffer, size);
 491         if (hash != ext4_xattr_inode_get_hash(ea_inode))
 492                 return -EFSCORRUPTED;
 493
 494         if (entry) {
 495                 __le32 e_hash, tmp_data;
 496
 497                 /* Verify entry hash. */
 498                 tmp_data = cpu_to_le32(hash);
 499                 e_hash = ext4_xattr_hash_entry(entry->e_name, entry->e_name_len,
 500                                                &tmp_data, 1);
 501                 /* All good? */
 502                 if (e_hash == entry->e_hash)
 503                         return 0;
 504
 505                 /*
 506                  * Not good. Maybe the entry hash was calculated
 507                  * using the buggy signed char version?
 508                  */
 509                 e_hash = ext4_xattr_hash_entry_signed(entry->e_name, entry->e_name_len,
 510                                                         &tmp_data, 1);
 511                 /* Still no match - bad */
 512                 if (e_hash != entry->e_hash)
 513                         return -EFSCORRUPTED;
 514
 515                 /* Let people know about old hash */
 516                 pr_warn_once("ext4: filesystem with signed xattr name hash");
 517         }
 518         return 0;
 519 }
 520
 521 /*
 522  * Read xattr value from the EA inode.
 523  */
 524 static int
 525 ext4_xattr_inode_get(struct inode *inode, struct ext4_xattr_entry *entry,
 526                      void *buffer, size_t size)
 527 {
 528         struct mb_cache *ea_inode_cache = EA_INODE_CACHE(inode);
 529         struct inode *ea_inode;
 530         int err;
 531
 532         err = ext4_xattr_inode_iget(inode, le32_to_cpu(entry->e_value_inum),
 533                                     le32_to_cpu(entry->e_hash), &ea_inode);
 534         if (err) {
 535                 ea_inode = NULL;
 536                 goto out;
 537         }
 538
 539         if (i_size_read(ea_inode) != size) {
 540                 ext4_warning_inode(ea_inode,
 541                                    "ea_inode file size=%llu entry size=%zu",
 542                                    i_size_read(ea_inode), size);
 543                 err = -EFSCORRUPTED;
 544                 goto out;
 545         }
 546
 547         err = ext4_xattr_inode_read(ea_inode, buffer, size);
 548         if (err)
 549                 goto out;
 550
 551         if (!ext4_test_inode_state(ea_inode, EXT4_STATE_LUSTRE_EA_INODE)) {
 552                 err = ext4_xattr_inode_verify_hashes(ea_inode, entry, buffer,
 553                                                      size);
 554                 if (err) {
 555                         ext4_warning_inode(ea_inode,
 556                                            "EA inode hash validation failed");
 557                         goto out;
 558                 }
 559
 560                 if (ea_inode_cache)
 561                         mb_cache_entry_create(ea_inode_cache, GFP_NOFS,
 562                                         ext4_xattr_inode_get_hash(ea_inode),
 563                                         ea_inode->i_ino, true /* reusable */);
 564         }
 565 out:
 566         iput(ea_inode);
 567         return err;
 568 }
 569
 570 static int
 571 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
 572                      void *buffer, size_t buffer_size)
 573 {
 574         struct buffer_head *bh = NULL;
 575         struct ext4_xattr_entry *entry;
 576         size_t size;
 577         void *end;
 578         int error;
 579         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
 580
 581         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 582                   name_index, name, buffer, (long)buffer_size);
 583
 584         if (!EXT4_I(inode)->i_file_acl)
 585                 return -ENODATA;
 586         ea_idebug(inode, "reading block %llu",
 587                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 588         bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
 589         if (IS_ERR(bh))
 590                 return PTR_ERR(bh);
 591         ea_bdebug(bh, "b_count=%d, refcount=%d",
 592                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 593         error = ext4_xattr_check_block(inode, bh);
 594         if (error)
 595                 goto cleanup;
 596         ext4_xattr_block_cache_insert(ea_block_cache, bh);
 597         entry = BFIRST(bh);
 598         end = bh->b_data + bh->b_size;
 599         error = xattr_find_entry(inode, &entry, end, name_index, name, 1);
 600         if (error)
 601                 goto cleanup;
 602         size = le32_to_cpu(entry->e_value_size);
 603         error = -ERANGE;
 604         if (unlikely(size > EXT4_XATTR_SIZE_MAX))
 605                 goto cleanup;
 606         if (buffer) {
 607                 if (size > buffer_size)
 608                         goto cleanup;
 609                 if (entry->e_value_inum) {
 610                         error = ext4_xattr_inode_get(inode, entry, buffer,
 611                                                      size);
 612                         if (error)
 613                                 goto cleanup;
 614                 } else {
 615                         u16 offset = le16_to_cpu(entry->e_value_offs);
 616                         void *p = bh->b_data + offset;
 617
 618                         if (unlikely(p + size > end))
 619                                 goto cleanup;
 620                         memcpy(buffer, p, size);
 621                 }
 622         }
 623         error = size;
 624
 625 cleanup:
 626         brelse(bh);
 627         return error;
 628 }
 629
 630 int
 631 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 632                      void *buffer, size_t buffer_size)
 633 {
 634         struct ext4_xattr_ibody_header *header;
 635         struct ext4_xattr_entry *entry;
 636         struct ext4_inode *raw_inode;
 637         struct ext4_iloc iloc;
 638         size_t size;
 639         void *end;
 640         int error;
 641
 642         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 643                 return -ENODATA;
 644         error = ext4_get_inode_loc(inode, &iloc);
 645         if (error)
 646                 return error;
 647         raw_inode = ext4_raw_inode(&iloc);
 648         header = IHDR(inode, raw_inode);
 649         end = ITAIL(inode, raw_inode);
 650         entry = IFIRST(header);
 651         error = xattr_find_entry(inode, &entry, end, name_index, name, 0);
 652         if (error)
 653                 goto cleanup;
 654         size = le32_to_cpu(entry->e_value_size);
 655         error = -ERANGE;
 656         if (unlikely(size > EXT4_XATTR_SIZE_MAX))
 657                 goto cleanup;
 658         if (buffer) {
 659                 if (size > buffer_size)
 660                         goto cleanup;
 661                 if (entry->e_value_inum) {
 662                         error = ext4_xattr_inode_get(inode, entry, buffer,
 663                                                      size);
 664                         if (error)
 665                                 goto cleanup;
 666                 } else {
 667                         u16 offset = le16_to_cpu(entry->e_value_offs);
 668                         void *p = (void *)IFIRST(header) + offset;
 669
 670                         if (unlikely(p + size > end))
 671                                 goto cleanup;
 672                         memcpy(buffer, p, size);
 673                 }
 674         }
 675         error = size;
 676
 677 cleanup:
 678         brelse(iloc.bh);
 679         return error;
 680 }
 681
 682 /*
 683  * ext4_xattr_get()
 684  *
 685  * Copy an extended attribute into the buffer
 686  * provided, or compute the buffer size required.
 687  * Buffer is NULL to compute the size of the buffer required.
 688  *
 689  * Returns a negative error number on failure, or the number of bytes
 690  * used / required on success.
 691  */
 692 int
 693 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
 694                void *buffer, size_t buffer_size)
 695 {
 696         int error;
 697
 698         if (unlikely(ext4_forced_shutdown(inode->i_sb)))
 699                 return -EIO;
 700
 701         if (strlen(name) > 255)
 702                 return -ERANGE;
 703
 704         down_read(&EXT4_I(inode)->xattr_sem);
 705         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
 706                                      buffer_size);
 707         if (error == -ENODATA)
 708                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
 709                                              buffer_size);
 710         up_read(&EXT4_I(inode)->xattr_sem);
 711         return error;
 712 }
 713
 714 static int
 715 ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,
 716                         char *buffer, size_t buffer_size)
 717 {
 718         size_t rest = buffer_size;
 719
 720         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 721                 const char *prefix;
 722
 723                 prefix = ext4_xattr_prefix(entry->e_name_index, dentry);
 724                 if (prefix) {
 725                         size_t prefix_len = strlen(prefix);
 726                         size_t size = prefix_len + entry->e_name_len + 1;
 727
 728                         if (buffer) {
 729                                 if (size > rest)
 730                                         return -ERANGE;
 731                                 memcpy(buffer, prefix, prefix_len);
 732                                 buffer += prefix_len;
 733                                 memcpy(buffer, entry->e_name, entry->e_name_len);
 734                                 buffer += entry->e_name_len;
 735                                 *buffer++ = 0;
 736                         }
 737                         rest -= size;
 738                 }
 739         }
 740         return buffer_size - rest;  /* total size */
 741 }
 742
 743 static int
 744 ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 745 {
 746         struct inode *inode = d_inode(dentry);
 747         struct buffer_head *bh = NULL;
 748         int error;
 749
 750         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 751                   buffer, (long)buffer_size);
 752
 753         if (!EXT4_I(inode)->i_file_acl)
 754                 return 0;
 755         ea_idebug(inode, "reading block %llu",
 756                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 757         bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
 758         if (IS_ERR(bh))
 759                 return PTR_ERR(bh);
 760         ea_bdebug(bh, "b_count=%d, refcount=%d",
 761                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 762         error = ext4_xattr_check_block(inode, bh);
 763         if (error)
 764                 goto cleanup;
 765         ext4_xattr_block_cache_insert(EA_BLOCK_CACHE(inode), bh);
 766         error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer,
 767                                         buffer_size);
 768 cleanup:
 769         brelse(bh);
 770         return error;
 771 }
 772
 773 static int
 774 ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 775 {
 776         struct inode *inode = d_inode(dentry);
 777         struct ext4_xattr_ibody_header *header;
 778         struct ext4_inode *raw_inode;
 779         struct ext4_iloc iloc;
 780         int error;
 781
 782         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 783                 return 0;
 784         error = ext4_get_inode_loc(inode, &iloc);
 785         if (error)
 786                 return error;
 787         raw_inode = ext4_raw_inode(&iloc);
 788         header = IHDR(inode, raw_inode);
 789         error = ext4_xattr_list_entries(dentry, IFIRST(header),
 790                                         buffer, buffer_size);
 791
 792         brelse(iloc.bh);
 793         return error;
 794 }
 795
 796 /*
 797  * Inode operation listxattr()
 798  *
 799  * d_inode(dentry)->i_rwsem: don't care
 800  *
 801  * Copy a list of attribute names into the buffer
 802  * provided, or compute the buffer size required.
 803  * Buffer is NULL to compute the size of the buffer required.
 804  *
 805  * Returns a negative error number on failure, or the number of bytes
 806  * used / required on success.
 807  */
 808 ssize_t
 809 ext4_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 810 {
 811         int ret, ret2;
 812
 813         down_read(&EXT4_I(d_inode(dentry))->xattr_sem);
 814         ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size);
 815         if (ret < 0)
 816                 goto errout;
 817         if (buffer) {
 818                 buffer += ret;
 819                 buffer_size -= ret;
 820         }
 821         ret = ext4_xattr_block_list(dentry, buffer, buffer_size);
 822         if (ret < 0)
 823                 goto errout;
 824         ret += ret2;
 825 errout:
 826         up_read(&EXT4_I(d_inode(dentry))->xattr_sem);
 827         return ret;
 828 }
 829
 830 /*
 831  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 832  * not set, set it.
 833  */
 834 static void ext4_xattr_update_super_block(handle_t *handle,
 835                                           struct super_block *sb)
 836 {
 837         if (ext4_has_feature_xattr(sb))
 838                 return;
 839
 840         BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
 841         if (ext4_journal_get_write_access(handle, sb, EXT4_SB(sb)->s_sbh,
 842                                           EXT4_JTR_NONE) == 0) {
 843                 lock_buffer(EXT4_SB(sb)->s_sbh);
 844                 ext4_set_feature_xattr(sb);
 845                 ext4_superblock_csum_set(sb);
 846                 unlock_buffer(EXT4_SB(sb)->s_sbh);
 847                 ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
 848         }
 849 }
 850
 851 int ext4_get_inode_usage(struct inode *inode, qsize_t *usage)
 852 {
 853         struct ext4_iloc iloc = { .bh = NULL };
 854         struct buffer_head *bh = NULL;
 855         struct ext4_inode *raw_inode;
 856         struct ext4_xattr_ibody_header *header;
 857         struct ext4_xattr_entry *entry;
 858         qsize_t ea_inode_refs = 0;
 859         int ret;
 860
 861         lockdep_assert_held_read(&EXT4_I(inode)->xattr_sem);
 862
 863         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
 864                 ret = ext4_get_inode_loc(inode, &iloc);
 865                 if (ret)
 866                         goto out;
 867                 raw_inode = ext4_raw_inode(&iloc);
 868                 header = IHDR(inode, raw_inode);
 869
 870                 for (entry = IFIRST(header); !IS_LAST_ENTRY(entry);
 871                      entry = EXT4_XATTR_NEXT(entry))
 872                         if (entry->e_value_inum)
 873                                 ea_inode_refs++;
 874         }
 875
 876         if (EXT4_I(inode)->i_file_acl) {
 877                 bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
 878                 if (IS_ERR(bh)) {
 879                         ret = PTR_ERR(bh);
 880                         bh = NULL;
 881                         goto out;
 882                 }
 883
 884                 ret = ext4_xattr_check_block(inode, bh);
 885                 if (ret)
 886                         goto out;
 887
 888                 for (entry = BFIRST(bh); !IS_LAST_ENTRY(entry);
 889                      entry = EXT4_XATTR_NEXT(entry))
 890                         if (entry->e_value_inum)
 891                                 ea_inode_refs++;
 892         }
 893         *usage = ea_inode_refs + 1;
 894         ret = 0;
 895 out:
 896         brelse(iloc.bh);
 897         brelse(bh);
 898         return ret;
 899 }
 900
 901 static inline size_t round_up_cluster(struct inode *inode, size_t length)
 902 {
 903         struct super_block *sb = inode->i_sb;
 904         size_t cluster_size = 1 << (EXT4_SB(sb)->s_cluster_bits +
 905                                     inode->i_blkbits);
 906         size_t mask = ~(cluster_size - 1);
 907
 908         return (length + cluster_size - 1) & mask;
 909 }
 910
 911 static int ext4_xattr_inode_alloc_quota(struct inode *inode, size_t len)
 912 {
 913         int err;
 914
 915         err = dquot_alloc_inode(inode);
 916         if (err)
 917                 return err;
 918         err = dquot_alloc_space_nodirty(inode, round_up_cluster(inode, len));
 919         if (err)
 920                 dquot_free_inode(inode);
 921         return err;
 922 }
 923
 924 static void ext4_xattr_inode_free_quota(struct inode *parent,
 925                                         struct inode *ea_inode,
 926                                         size_t len)
 927 {
 928         if (ea_inode &&
 929             ext4_test_inode_state(ea_inode, EXT4_STATE_LUSTRE_EA_INODE))
 930                 return;
 931         dquot_free_space_nodirty(parent, round_up_cluster(parent, len));
 932         dquot_free_inode(parent);
 933 }
 934
 935 int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode,
 936                              struct buffer_head *block_bh, size_t value_len,
 937                              bool is_create)
 938 {
 939         int credits;
 940         int blocks;
 941
 942         /*
 943          * 1) Owner inode update
 944          * 2) Ref count update on old xattr block
 945          * 3) new xattr block
 946          * 4) block bitmap update for new xattr block
 947          * 5) group descriptor for new xattr block
 948          * 6) block bitmap update for old xattr block
 949          * 7) group descriptor for old block
 950          *
 951          * 6 & 7 can happen if we have two racing threads T_a and T_b
 952          * which are each trying to set an xattr on inodes I_a and I_b
 953          * which were both initially sharing an xattr block.
 954          */
 955         credits = 7;
 956
 957         /* Quota updates. */
 958         credits += EXT4_MAXQUOTAS_TRANS_BLOCKS(sb);
 959
 960         /*
 961          * In case of inline data, we may push out the data to a block,
 962          * so we need to reserve credits for this eventuality
 963          */
 964         if (inode && ext4_has_inline_data(inode))
 965                 credits += ext4_writepage_trans_blocks(inode) + 1;
 966
 967         /* We are done if ea_inode feature is not enabled. */
 968         if (!ext4_has_feature_ea_inode(sb))
 969                 return credits;
 970
 971         /* New ea_inode, inode map, block bitmap, group descriptor. */
 972         credits += 4;
 973
 974         /* Data blocks. */
 975         blocks = (value_len + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
 976
 977         /* Indirection block or one level of extent tree. */
 978         blocks += 1;
 979
 980         /* Block bitmap and group descriptor updates for each block. */
 981         credits += blocks * 2;
 982
 983         /* Blocks themselves. */
 984         credits += blocks;
 985
 986         if (!is_create) {
 987                 /* Dereference ea_inode holding old xattr value.
 988                  * Old ea_inode, inode map, block bitmap, group descriptor.
 989                  */
 990                 credits += 4;
 991
 992                 /* Data blocks for old ea_inode. */
 993                 blocks = XATTR_SIZE_MAX >> sb->s_blocksize_bits;
 994
 995                 /* Indirection block or one level of extent tree for old
 996                  * ea_inode.
 997                  */
 998                 blocks += 1;
 999
1000                 /* Block bitmap and group descriptor updates for each block. */
1001                 credits += blocks * 2;
1002         }
1003
1004         /* We may need to clone the existing xattr block in which case we need
1005          * to increment ref counts for existing ea_inodes referenced by it.
1006          */
1007         if (block_bh) {
1008                 struct ext4_xattr_entry *entry = BFIRST(block_bh);
1009
1010                 for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry))
1011                         if (entry->e_value_inum)
1012                                 /* Ref count update on ea_inode. */
1013                                 credits += 1;
1014         }
1015         return credits;
1016 }
1017
1018 static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode,
1019                                        int ref_change)
1020 {
1021         struct ext4_iloc iloc;
1022         s64 ref_count;
1023         int ret;
1024
1025         inode_lock_nested(ea_inode, I_MUTEX_XATTR);
1026
1027         ret = ext4_reserve_inode_write(handle, ea_inode, &iloc);
1028         if (ret)
1029                 goto out;
1030
1031         ref_count = ext4_xattr_inode_get_ref(ea_inode);
1032         ref_count += ref_change;
1033         ext4_xattr_inode_set_ref(ea_inode, ref_count);
1034
1035         if (ref_change > 0) {
1036                 WARN_ONCE(ref_count <= 0, "EA inode %lu ref_count=%lld",
1037                           ea_inode->i_ino, ref_count);
1038
1039                 if (ref_count == 1) {
1040                         WARN_ONCE(ea_inode->i_nlink, "EA inode %lu i_nlink=%u",
1041                                   ea_inode->i_ino, ea_inode->i_nlink);
1042
1043                         set_nlink(ea_inode, 1);
1044                         ext4_orphan_del(handle, ea_inode);
1045                 }
1046         } else {
1047                 WARN_ONCE(ref_count < 0, "EA inode %lu ref_count=%lld",
1048                           ea_inode->i_ino, ref_count);
1049
1050                 if (ref_count == 0) {
1051                         WARN_ONCE(ea_inode->i_nlink != 1,
1052                                   "EA inode %lu i_nlink=%u",
1053                                   ea_inode->i_ino, ea_inode->i_nlink);
1054
1055                         clear_nlink(ea_inode);
1056                         ext4_orphan_add(handle, ea_inode);
1057                 }
1058         }
1059
1060         ret = ext4_mark_iloc_dirty(handle, ea_inode, &iloc);
1061         if (ret)
1062                 ext4_warning_inode(ea_inode,
1063                                    "ext4_mark_iloc_dirty() failed ret=%d", ret);
1064 out:
1065         inode_unlock(ea_inode);
1066         return ret;
1067 }
1068
1069 static int ext4_xattr_inode_inc_ref(handle_t *handle, struct inode *ea_inode)
1070 {
1071         return ext4_xattr_inode_update_ref(handle, ea_inode, 1);
1072 }
1073
1074 static int ext4_xattr_inode_dec_ref(handle_t *handle, struct inode *ea_inode)
1075 {
1076         return ext4_xattr_inode_update_ref(handle, ea_inode, -1);
1077 }
1078
1079 static int ext4_xattr_inode_inc_ref_all(handle_t *handle, struct inode *parent,
1080                                         struct ext4_xattr_entry *first)
1081 {
1082         struct inode *ea_inode;
1083         struct ext4_xattr_entry *entry;
1084         struct ext4_xattr_entry *failed_entry;
1085         unsigned int ea_ino;
1086         int err, saved_err;
1087
1088         for (entry = first; !IS_LAST_ENTRY(entry);
1089              entry = EXT4_XATTR_NEXT(entry)) {
1090                 if (!entry->e_value_inum)
1091                         continue;
1092                 ea_ino = le32_to_cpu(entry->e_value_inum);
1093                 err = ext4_xattr_inode_iget(parent, ea_ino,
1094                                             le32_to_cpu(entry->e_hash),
1095                                             &ea_inode);
1096                 if (err)
1097                         goto cleanup;
1098                 err = ext4_xattr_inode_inc_ref(handle, ea_inode);
1099                 if (err) {
1100                         ext4_warning_inode(ea_inode, "inc ref error %d", err);
1101                         iput(ea_inode);
1102                         goto cleanup;
1103                 }
1104                 iput(ea_inode);
1105         }
1106         return 0;
1107
1108 cleanup:
1109         saved_err = err;
1110         failed_entry = entry;
1111
1112         for (entry = first; entry != failed_entry;
1113              entry = EXT4_XATTR_NEXT(entry)) {
1114                 if (!entry->e_value_inum)
1115                         continue;
1116                 ea_ino = le32_to_cpu(entry->e_value_inum);
1117                 err = ext4_xattr_inode_iget(parent, ea_ino,
1118                                             le32_to_cpu(entry->e_hash),
1119                                             &ea_inode);
1120                 if (err) {
1121                         ext4_warning(parent->i_sb,
1122                                      "cleanup ea_ino %u iget error %d", ea_ino,
1123                                      err);
1124                         continue;
1125                 }
1126                 err = ext4_xattr_inode_dec_ref(handle, ea_inode);
1127                 if (err)
1128                         ext4_warning_inode(ea_inode, "cleanup dec ref error %d",
1129                                            err);
1130                 iput(ea_inode);
1131         }
1132         return saved_err;
1133 }
1134
1135 static int ext4_xattr_restart_fn(handle_t *handle, struct inode *inode,
1136                         struct buffer_head *bh, bool block_csum, bool dirty)
1137 {
1138         int error;
1139
1140         if (bh && dirty) {
1141                 if (block_csum)
1142                         ext4_xattr_block_csum_set(inode, bh);
1143                 error = ext4_handle_dirty_metadata(handle, NULL, bh);
1144                 if (error) {
1145                         ext4_warning(inode->i_sb, "Handle metadata (error %d)",
1146                                      error);
1147                         return error;
1148                 }
1149         }
1150         return 0;
1151 }
1152
1153 static void
1154 ext4_xattr_inode_dec_ref_all(handle_t *handle, struct inode *parent,
1155                              struct buffer_head *bh,
1156                              struct ext4_xattr_entry *first, bool block_csum,
1157                              struct ext4_xattr_inode_array **ea_inode_array,
1158                              int extra_credits, bool skip_quota)
1159 {
1160         struct inode *ea_inode;
1161         struct ext4_xattr_entry *entry;
1162         struct ext4_iloc iloc;
1163         bool dirty = false;
1164         unsigned int ea_ino;
1165         int err;
1166         int credits;
1167         void *end;
1168
1169         if (block_csum)
1170                 end = (void *)bh->b_data + bh->b_size;
1171         else {
1172                 ext4_get_inode_loc(parent, &iloc);
1173                 end = (void *)ext4_raw_inode(&iloc) + EXT4_SB(parent->i_sb)->s_inode_size;
1174         }
1175
1176         /* One credit for dec ref on ea_inode, one for orphan list addition, */
1177         credits = 2 + extra_credits;
1178
1179         for (entry = first; (void *)entry < end && !IS_LAST_ENTRY(entry);
1180              entry = EXT4_XATTR_NEXT(entry)) {
1181                 if (!entry->e_value_inum)
1182                         continue;
1183                 ea_ino = le32_to_cpu(entry->e_value_inum);
1184                 err = ext4_xattr_inode_iget(parent, ea_ino,
1185                                             le32_to_cpu(entry->e_hash),
1186                                             &ea_inode);
1187                 if (err)
1188                         continue;
1189
1190                 err = ext4_expand_inode_array(ea_inode_array, ea_inode);
1191                 if (err) {
1192                         ext4_warning_inode(ea_inode,
1193                                            "Expand inode array err=%d", err);
1194                         iput(ea_inode);
1195                         continue;
1196                 }
1197
1198                 err = ext4_journal_ensure_credits_fn(handle, credits, credits,
1199                         ext4_free_metadata_revoke_credits(parent->i_sb, 1),
1200                         ext4_xattr_restart_fn(handle, parent, bh, block_csum,
1201                                               dirty));
1202                 if (err < 0) {
1203                         ext4_warning_inode(ea_inode, "Ensure credits err=%d",
1204                                            err);
1205                         continue;
1206                 }
1207                 if (err > 0) {
1208                         err = ext4_journal_get_write_access(handle,
1209                                         parent->i_sb, bh, EXT4_JTR_NONE);
1210                         if (err) {
1211                                 ext4_warning_inode(ea_inode,
1212                                                 "Re-get write access err=%d",
1213                                                 err);
1214                                 continue;
1215                         }
1216                 }
1217
1218                 err = ext4_xattr_inode_dec_ref(handle, ea_inode);
1219                 if (err) {
1220                         ext4_warning_inode(ea_inode, "ea_inode dec ref err=%d",
1221                                            err);
1222                         continue;
1223                 }
1224
1225                 if (!skip_quota)
1226                         ext4_xattr_inode_free_quota(parent, ea_inode,
1227                                               le32_to_cpu(entry->e_value_size));
1228
1229                 /*
1230                  * Forget about ea_inode within the same transaction that
1231                  * decrements the ref count. This avoids duplicate decrements in
1232                  * case the rest of the work spills over to subsequent
1233                  * transactions.
1234                  */
1235                 entry->e_value_inum = 0;
1236                 entry->e_value_size = 0;
1237
1238                 dirty = true;
1239         }
1240
1241         if (dirty) {
1242                 /*
1243                  * Note that we are deliberately skipping csum calculation for
1244                  * the final update because we do not expect any journal
1245                  * restarts until xattr block is freed.
1246                  */
1247
1248                 err = ext4_handle_dirty_metadata(handle, NULL, bh);
1249                 if (err)
1250                         ext4_warning_inode(parent,
1251                                            "handle dirty metadata err=%d", err);
1252         }
1253 }
1254
1255 /*
1256  * Release the xattr block BH: If the reference count is > 1, decrement it;
1257  * otherwise free the block.
1258  */
1259 static void
1260 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
1261                          struct buffer_head *bh,
1262                          struct ext4_xattr_inode_array **ea_inode_array,
1263                          int extra_credits)
1264 {
1265         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
1266         u32 hash, ref;
1267         int error = 0;
1268
1269         BUFFER_TRACE(bh, "get_write_access");
1270         error = ext4_journal_get_write_access(handle, inode->i_sb, bh,
1271                                               EXT4_JTR_NONE);
1272         if (error)
1273                 goto out;
1274
1275 retry_ref:
1276         lock_buffer(bh);
1277         hash = le32_to_cpu(BHDR(bh)->h_hash);
1278         ref = le32_to_cpu(BHDR(bh)->h_refcount);
1279         if (ref == 1) {
1280                 ea_bdebug(bh, "refcount now=0; freeing");
1281                 /*
1282                  * This must happen under buffer lock for
1283                  * ext4_xattr_block_set() to reliably detect freed block
1284                  */
1285                 if (ea_block_cache) {
1286                         struct mb_cache_entry *oe;
1287
1288                         oe = mb_cache_entry_delete_or_get(ea_block_cache, hash,
1289                                                           bh->b_blocknr);
1290                         if (oe) {
1291                                 unlock_buffer(bh);
1292                                 mb_cache_entry_wait_unused(oe);
1293                                 mb_cache_entry_put(ea_block_cache, oe);
1294                                 goto retry_ref;
1295                         }
1296                 }
1297                 get_bh(bh);
1298                 unlock_buffer(bh);
1299
1300                 if (ext4_has_feature_ea_inode(inode->i_sb))
1301                         ext4_xattr_inode_dec_ref_all(handle, inode, bh,
1302                                                      BFIRST(bh),
1303                                                      true /* block_csum */,
1304                                                      ea_inode_array,
1305                                                      extra_credits,
1306                                                      true /* skip_quota */);
1307                 ext4_free_blocks(handle, inode, bh, 0, 1,
1308                                  EXT4_FREE_BLOCKS_METADATA |
1309                                  EXT4_FREE_BLOCKS_FORGET);
1310         } else {
1311                 ref--;
1312                 BHDR(bh)->h_refcount = cpu_to_le32(ref);
1313                 if (ref == EXT4_XATTR_REFCOUNT_MAX - 1) {
1314                         struct mb_cache_entry *ce;
1315
1316                         if (ea_block_cache) {
1317                                 ce = mb_cache_entry_get(ea_block_cache, hash,
1318                                                         bh->b_blocknr);
1319                                 if (ce) {
1320                                         set_bit(MBE_REUSABLE_B, &ce->e_flags);
1321                                         mb_cache_entry_put(ea_block_cache, ce);
1322                                 }
1323                         }
1324                 }
1325
1326                 ext4_xattr_block_csum_set(inode, bh);
1327                 /*
1328                  * Beware of this ugliness: Releasing of xattr block references
1329                  * from different inodes can race and so we have to protect
1330                  * from a race where someone else frees the block (and releases
1331                  * its journal_head) before we are done dirtying the buffer. In
1332                  * nojournal mode this race is harmless and we actually cannot
1333                  * call ext4_handle_dirty_metadata() with locked buffer as
1334                  * that function can call sync_dirty_buffer() so for that case
1335                  * we handle the dirtying after unlocking the buffer.
1336                  */
1337                 if (ext4_handle_valid(handle))
1338                         error = ext4_handle_dirty_metadata(handle, inode, bh);
1339                 unlock_buffer(bh);
1340                 if (!ext4_handle_valid(handle))
1341                         error = ext4_handle_dirty_metadata(handle, inode, bh);
1342                 if (IS_SYNC(inode))
1343                         ext4_handle_sync(handle);
1344                 dquot_free_block(inode, EXT4_C2B(EXT4_SB(inode->i_sb), 1));
1345                 ea_bdebug(bh, "refcount now=%d; releasing",
1346                           le32_to_cpu(BHDR(bh)->h_refcount));
1347         }
1348 out:
1349         ext4_std_error(inode->i_sb, error);
1350         return;
1351 }
1352
1353 /*
1354  * Find the available free space for EAs. This also returns the total number of
1355  * bytes used by EA entries.
1356  */
1357 static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
1358                                     size_t *min_offs, void *base, int *total)
1359 {
1360         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1361                 if (!last->e_value_inum && last->e_value_size) {
1362                         size_t offs = le16_to_cpu(last->e_value_offs);
1363                         if (offs < *min_offs)
1364                                 *min_offs = offs;
1365                 }
1366                 if (total)
1367                         *total += EXT4_XATTR_LEN(last->e_name_len);
1368         }
1369         return (*min_offs - ((void *)last - base) - sizeof(__u32));
1370 }
1371
1372 /*
1373  * Write the value of the EA in an inode.
1374  */
1375 static int ext4_xattr_inode_write(handle_t *handle, struct inode *ea_inode,
1376                                   const void *buf, int bufsize)
1377 {
1378         struct buffer_head *bh = NULL;
1379         unsigned long block = 0;
1380         int blocksize = ea_inode->i_sb->s_blocksize;
1381         int max_blocks = (bufsize + blocksize - 1) >> ea_inode->i_blkbits;
1382         int csize, wsize = 0;
1383         int ret = 0, ret2 = 0;
1384         int retries = 0;
1385
1386 retry:
1387         while (ret >= 0 && ret < max_blocks) {
1388                 struct ext4_map_blocks map;
1389                 map.m_lblk = block += ret;
1390                 map.m_len = max_blocks -= ret;
1391
1392                 ret = ext4_map_blocks(handle, ea_inode, &map,
1393                                       EXT4_GET_BLOCKS_CREATE);
1394                 if (ret <= 0) {
1395                         ext4_mark_inode_dirty(handle, ea_inode);
1396                         if (ret == -ENOSPC &&
1397                             ext4_should_retry_alloc(ea_inode->i_sb, &retries)) {
1398                                 ret = 0;
1399                                 goto retry;
1400                         }
1401                         break;
1402                 }
1403         }
1404
1405         if (ret < 0)
1406                 return ret;
1407
1408         block = 0;
1409         while (wsize < bufsize) {
1410                 brelse(bh);
1411                 csize = (bufsize - wsize) > blocksize ? blocksize :
1412                                                                 bufsize - wsize;
1413                 bh = ext4_getblk(handle, ea_inode, block, 0);
1414                 if (IS_ERR(bh))
1415                         return PTR_ERR(bh);
1416                 if (!bh) {
1417                         WARN_ON_ONCE(1);
1418                         EXT4_ERROR_INODE(ea_inode,
1419                                          "ext4_getblk() return bh = NULL");
1420                         return -EFSCORRUPTED;
1421                 }
1422                 ret = ext4_journal_get_write_access(handle, ea_inode->i_sb, bh,
1423                                                    EXT4_JTR_NONE);
1424                 if (ret)
1425                         goto out;
1426
1427                 memcpy(bh->b_data, buf, csize);
1428                 /*
1429                  * Zero out block tail to avoid writing uninitialized memory
1430                  * to disk.
1431                  */
1432                 if (csize < blocksize)
1433                         memset(bh->b_data + csize, 0, blocksize - csize);
1434                 set_buffer_uptodate(bh);
1435                 ext4_handle_dirty_metadata(handle, ea_inode, bh);
1436
1437                 buf += csize;
1438                 wsize += csize;
1439                 block += 1;
1440         }
1441
1442         inode_lock(ea_inode);
1443         i_size_write(ea_inode, wsize);
1444         ext4_update_i_disksize(ea_inode, wsize);
1445         inode_unlock(ea_inode);
1446
1447         ret2 = ext4_mark_inode_dirty(handle, ea_inode);
1448         if (unlikely(ret2 && !ret))
1449                 ret = ret2;
1450
1451 out:
1452         brelse(bh);
1453
1454         return ret;
1455 }
1456
1457 /*
1458  * Create an inode to store the value of a large EA.
1459  */
1460 static struct inode *ext4_xattr_inode_create(handle_t *handle,
1461                                              struct inode *inode, u32 hash)
1462 {
1463         struct inode *ea_inode = NULL;
1464         uid_t owner[2] = { i_uid_read(inode), i_gid_read(inode) };
1465         int err;
1466
1467         if (inode->i_sb->s_root == NULL) {
1468                 ext4_warning(inode->i_sb,
1469                              "refuse to create EA inode when umounting");
1470                 WARN_ON(1);
1471                 return ERR_PTR(-EINVAL);
1472         }
1473
1474         /*
1475          * Let the next inode be the goal, so we try and allocate the EA inode
1476          * in the same group, or nearby one.
1477          */
1478         ea_inode = ext4_new_inode(handle, inode->i_sb->s_root->d_inode,
1479                                   S_IFREG | 0600, NULL, inode->i_ino + 1, owner,
1480                                   EXT4_EA_INODE_FL);
1481         if (!IS_ERR(ea_inode)) {
1482                 ea_inode->i_op = &ext4_file_inode_operations;
1483                 ea_inode->i_fop = &ext4_file_operations;
1484                 ext4_set_aops(ea_inode);
1485                 ext4_xattr_inode_set_class(ea_inode);
1486                 unlock_new_inode(ea_inode);
1487                 ext4_xattr_inode_set_ref(ea_inode, 1);
1488                 ext4_xattr_inode_set_hash(ea_inode, hash);
1489                 err = ext4_mark_inode_dirty(handle, ea_inode);
1490                 if (!err)
1491                         err = ext4_inode_attach_jinode(ea_inode);
1492                 if (err) {
1493                         if (ext4_xattr_inode_dec_ref(handle, ea_inode))
1494                                 ext4_warning_inode(ea_inode,
1495                                         "cleanup dec ref error %d", err);
1496                         iput(ea_inode);
1497                         return ERR_PTR(err);
1498                 }
1499
1500                 /*
1501                  * Xattr inodes are shared therefore quota charging is performed
1502                  * at a higher level.
1503                  */
1504                 dquot_free_inode(ea_inode);
1505                 dquot_drop(ea_inode);
1506                 inode_lock(ea_inode);
1507                 ea_inode->i_flags |= S_NOQUOTA;
1508                 inode_unlock(ea_inode);
1509         }
1510
1511         return ea_inode;
1512 }
1513
1514 static struct inode *
1515 ext4_xattr_inode_cache_find(struct inode *inode, const void *value,
1516                             size_t value_len, u32 hash)
1517 {
1518         struct inode *ea_inode;
1519         struct mb_cache_entry *ce;
1520         struct mb_cache *ea_inode_cache = EA_INODE_CACHE(inode);
1521         void *ea_data;
1522
1523         if (!ea_inode_cache)
1524                 return NULL;
1525
1526         ce = mb_cache_entry_find_first(ea_inode_cache, hash);
1527         if (!ce)
1528                 return NULL;
1529
1530         WARN_ON_ONCE(ext4_handle_valid(journal_current_handle()) &&
1531                      !(current->flags & PF_MEMALLOC_NOFS));
1532
1533         ea_data = kvmalloc(value_len, GFP_KERNEL);
1534         if (!ea_data) {
1535                 mb_cache_entry_put(ea_inode_cache, ce);
1536                 return NULL;
1537         }
1538
1539         while (ce) {
1540                 ea_inode = ext4_iget(inode->i_sb, ce->e_value,
1541                                      EXT4_IGET_EA_INODE);
1542                 if (IS_ERR(ea_inode))
1543                         goto next_entry;
1544                 ext4_xattr_inode_set_class(ea_inode);
1545                 if (i_size_read(ea_inode) == value_len &&
1546                     !ext4_xattr_inode_read(ea_inode, ea_data, value_len) &&
1547                     !ext4_xattr_inode_verify_hashes(ea_inode, NULL, ea_data,
1548                                                     value_len) &&
1549                     !memcmp(value, ea_data, value_len)) {
1550                         mb_cache_entry_touch(ea_inode_cache, ce);
1551                         mb_cache_entry_put(ea_inode_cache, ce);
1552                         kvfree(ea_data);
1553                         return ea_inode;
1554                 }
1555                 iput(ea_inode);
1556         next_entry:
1557                 ce = mb_cache_entry_find_next(ea_inode_cache, ce);
1558         }
1559         kvfree(ea_data);
1560         return NULL;
1561 }
1562
1563 /*
1564  * Add value of the EA in an inode.
1565  */
1566 static struct inode *ext4_xattr_inode_lookup_create(handle_t *handle,
1567                 struct inode *inode, const void *value, size_t value_len)
1568 {
1569         struct inode *ea_inode;
1570         u32 hash;
1571         int err;
1572
1573         /* Account inode & space to quota even if sharing... */
1574         err = ext4_xattr_inode_alloc_quota(inode, value_len);
1575         if (err)
1576                 return ERR_PTR(err);
1577
1578         hash = ext4_xattr_inode_hash(EXT4_SB(inode->i_sb), value, value_len);
1579         ea_inode = ext4_xattr_inode_cache_find(inode, value, value_len, hash);
1580         if (ea_inode) {
1581                 err = ext4_xattr_inode_inc_ref(handle, ea_inode);
1582                 if (err)
1583                         goto out_err;
1584                 return ea_inode;
1585         }
1586
1587         /* Create an inode for the EA value */
1588         ea_inode = ext4_xattr_inode_create(handle, inode, hash);
1589         if (IS_ERR(ea_inode)) {
1590                 ext4_xattr_inode_free_quota(inode, NULL, value_len);
1591                 return ea_inode;
1592         }
1593
1594         err = ext4_xattr_inode_write(handle, ea_inode, value, value_len);
1595         if (err) {
1596                 if (ext4_xattr_inode_dec_ref(handle, ea_inode))
1597                         ext4_warning_inode(ea_inode, "cleanup dec ref error %d", err);
1598                 goto out_err;
1599         }
1600
1601         if (EA_INODE_CACHE(inode))
1602                 mb_cache_entry_create(EA_INODE_CACHE(inode), GFP_NOFS, hash,
1603                                       ea_inode->i_ino, true /* reusable */);
1604         return ea_inode;
1605 out_err:
1606         iput(ea_inode);
1607         ext4_xattr_inode_free_quota(inode, NULL, value_len);
1608         return ERR_PTR(err);
1609 }
1610
1611 /*
1612  * Reserve min(block_size/8, 1024) bytes for xattr entries/names if ea_inode
1613  * feature is enabled.
1614  */
1615 #define EXT4_XATTR_BLOCK_RESERVE(inode) min(i_blocksize(inode)/8, 1024U)
1616
1617 static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
1618                                 struct ext4_xattr_search *s,
1619                                 handle_t *handle, struct inode *inode,
1620                                 struct inode *new_ea_inode,
1621                                 bool is_block)
1622 {
1623         struct ext4_xattr_entry *last, *next;
1624         struct ext4_xattr_entry *here = s->here;
1625         size_t min_offs = s->end - s->base, name_len = strlen(i->name);
1626         int in_inode = i->in_inode;
1627         struct inode *old_ea_inode = NULL;
1628         size_t old_size, new_size;
1629         int ret;
1630
1631         /* Space used by old and new values. */
1632         old_size = (!s->not_found && !here->e_value_inum) ?
1633                         EXT4_XATTR_SIZE(le32_to_cpu(here->e_value_size)) : 0;
1634         new_size = (i->value && !in_inode) ? EXT4_XATTR_SIZE(i->value_len) : 0;
1635
1636         /*
1637          * Optimization for the simple case when old and new values have the
1638          * same padded sizes. Not applicable if external inodes are involved.
1639          */
1640         if (new_size && new_size == old_size) {
1641                 size_t offs = le16_to_cpu(here->e_value_offs);
1642                 void *val = s->base + offs;
1643
1644                 here->e_value_size = cpu_to_le32(i->value_len);
1645                 if (i->value == EXT4_ZERO_XATTR_VALUE) {
1646                         memset(val, 0, new_size);
1647                 } else {
1648                         memcpy(val, i->value, i->value_len);
1649                         /* Clear padding bytes. */
1650                         memset(val + i->value_len, 0, new_size - i->value_len);
1651                 }
1652                 goto update_hash;
1653         }
1654
1655         /* Compute min_offs and last. */
1656         last = s->first;
1657         for (; !IS_LAST_ENTRY(last); last = next) {
1658                 next = EXT4_XATTR_NEXT(last);
1659                 if ((void *)next >= s->end) {
1660                         EXT4_ERROR_INODE(inode, "corrupted xattr entries");
1661                         ret = -EFSCORRUPTED;
1662                         goto out;
1663                 }
1664                 if (!last->e_value_inum && last->e_value_size) {
1665                         size_t offs = le16_to_cpu(last->e_value_offs);
1666                         if (offs < min_offs)
1667                                 min_offs = offs;
1668                 }
1669         }
1670
1671         /* Check whether we have enough space. */
1672         if (i->value) {
1673                 size_t free;
1674
1675                 free = min_offs - ((void *)last - s->base) - sizeof(__u32);
1676                 if (!s->not_found)
1677                         free += EXT4_XATTR_LEN(name_len) + old_size;
1678
1679                 if (free < EXT4_XATTR_LEN(name_len) + new_size) {
1680                         ret = -ENOSPC;
1681                         goto out;
1682                 }
1683
1684                 /*
1685                  * If storing the value in an external inode is an option,
1686                  * reserve space for xattr entries/names in the external
1687                  * attribute block so that a long value does not occupy the
1688                  * whole space and prevent further entries being added.
1689                  */
1690                 if (ext4_has_feature_ea_inode(inode->i_sb) &&
1691                     new_size && is_block &&
1692                     (min_offs + old_size - new_size) <
1693                                         EXT4_XATTR_BLOCK_RESERVE(inode)) {
1694                         ret = -ENOSPC;
1695                         goto out;
1696                 }
1697         }
1698
1699         /*
1700          * Getting access to old and new ea inodes is subject to failures.
1701          * Finish that work before doing any modifications to the xattr data.
1702          */
1703         if (!s->not_found && here->e_value_inum) {
1704                 ret = ext4_xattr_inode_iget(inode,
1705                                             le32_to_cpu(here->e_value_inum),
1706                                             le32_to_cpu(here->e_hash),
1707                                             &old_ea_inode);
1708                 if (ret) {
1709                         old_ea_inode = NULL;
1710                         goto out;
1711                 }
1712
1713                 /* We are ready to release ref count on the old_ea_inode. */
1714                 ret = ext4_xattr_inode_dec_ref(handle, old_ea_inode);
1715                 if (ret)
1716                         goto out;
1717
1718                 ext4_xattr_inode_free_quota(inode, old_ea_inode,
1719                                             le32_to_cpu(here->e_value_size));
1720         }
1721
1722         /* No failures allowed past this point. */
1723
1724         if (!s->not_found && here->e_value_size && !here->e_value_inum) {
1725                 /* Remove the old value. */
1726                 void *first_val = s->base + min_offs;
1727                 size_t offs = le16_to_cpu(here->e_value_offs);
1728                 void *val = s->base + offs;
1729
1730                 memmove(first_val + old_size, first_val, val - first_val);
1731                 memset(first_val, 0, old_size);
1732                 min_offs += old_size;
1733
1734                 /* Adjust all value offsets. */
1735                 last = s->first;
1736                 while (!IS_LAST_ENTRY(last)) {
1737                         size_t o = le16_to_cpu(last->e_value_offs);
1738
1739                         if (!last->e_value_inum &&
1740                             last->e_value_size && o < offs)
1741                                 last->e_value_offs = cpu_to_le16(o + old_size);
1742                         last = EXT4_XATTR_NEXT(last);
1743                 }
1744         }
1745
1746         if (!i->value) {
1747                 /* Remove old name. */
1748                 size_t size = EXT4_XATTR_LEN(name_len);
1749
1750                 last = ENTRY((void *)last - size);
1751                 memmove(here, (void *)here + size,
1752                         (void *)last - (void *)here + sizeof(__u32));
1753                 memset(last, 0, size);
1754
1755                 /*
1756                  * Update i_inline_off - moved ibody region might contain
1757                  * system.data attribute.  Handling a failure here won't
1758                  * cause other complications for setting an xattr.
1759                  */
1760                 if (!is_block && ext4_has_inline_data(inode)) {
1761                         ret = ext4_find_inline_data_nolock(inode);
1762                         if (ret) {
1763                                 ext4_warning_inode(inode,
1764                                         "unable to update i_inline_off");
1765                                 goto out;
1766                         }
1767                 }
1768         } else if (s->not_found) {
1769                 /* Insert new name. */
1770                 size_t size = EXT4_XATTR_LEN(name_len);
1771                 size_t rest = (void *)last - (void *)here + sizeof(__u32);
1772
1773                 memmove((void *)here + size, here, rest);
1774                 memset(here, 0, size);
1775                 here->e_name_index = i->name_index;
1776                 here->e_name_len = name_len;
1777                 memcpy(here->e_name, i->name, name_len);
1778         } else {
1779                 /* This is an update, reset value info. */
1780                 here->e_value_inum = 0;
1781                 here->e_value_offs = 0;
1782                 here->e_value_size = 0;
1783         }
1784
1785         if (i->value) {
1786                 /* Insert new value. */
1787                 if (in_inode) {
1788                         here->e_value_inum = cpu_to_le32(new_ea_inode->i_ino);
1789                 } else if (i->value_len) {
1790                         void *val = s->base + min_offs - new_size;
1791
1792                         here->e_value_offs = cpu_to_le16(min_offs - new_size);
1793                         if (i->value == EXT4_ZERO_XATTR_VALUE) {
1794                                 memset(val, 0, new_size);
1795                         } else {
1796                                 memcpy(val, i->value, i->value_len);
1797                                 /* Clear padding bytes. */
1798                                 memset(val + i->value_len, 0,
1799                                        new_size - i->value_len);
1800                         }
1801                 }
1802                 here->e_value_size = cpu_to_le32(i->value_len);
1803         }
1804
1805 update_hash:
1806         if (i->value) {
1807                 __le32 hash = 0;
1808
1809                 /* Entry hash calculation. */
1810                 if (in_inode) {
1811                         __le32 crc32c_hash;
1812
1813                         /*
1814                          * Feed crc32c hash instead of the raw value for entry
1815                          * hash calculation. This is to avoid walking
1816                          * potentially long value buffer again.
1817                          */
1818                         crc32c_hash = cpu_to_le32(
1819                                        ext4_xattr_inode_get_hash(new_ea_inode));
1820                         hash = ext4_xattr_hash_entry(here->e_name,
1821                                                      here->e_name_len,
1822                                                      &crc32c_hash, 1);
1823                 } else if (is_block) {
1824                         __le32 *value = s->base + le16_to_cpu(
1825                                                         here->e_value_offs);
1826
1827                         hash = ext4_xattr_hash_entry(here->e_name,
1828                                                      here->e_name_len, value,
1829                                                      new_size >> 2);
1830                 }
1831                 here->e_hash = hash;
1832         }
1833
1834         if (is_block)
1835                 ext4_xattr_rehash((struct ext4_xattr_header *)s->base);
1836
1837         ret = 0;
1838 out:
1839         iput(old_ea_inode);
1840         return ret;
1841 }
1842
1843 struct ext4_xattr_block_find {
1844         struct ext4_xattr_search s;
1845         struct buffer_head *bh;
1846 };
1847
1848 static int
1849 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
1850                       struct ext4_xattr_block_find *bs)
1851 {
1852         struct super_block *sb = inode->i_sb;
1853         int error;
1854
1855         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
1856                   i->name_index, i->name, i->value, (long)i->value_len);
1857
1858         if (EXT4_I(inode)->i_file_acl) {
1859                 /* The inode already has an extended attribute block. */
1860                 bs->bh = ext4_sb_bread(sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
1861                 if (IS_ERR(bs->bh)) {
1862                         error = PTR_ERR(bs->bh);
1863                         bs->bh = NULL;
1864                         return error;
1865                 }
1866                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
1867                         atomic_read(&(bs->bh->b_count)),
1868                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
1869                 error = ext4_xattr_check_block(inode, bs->bh);
1870                 if (error)
1871                         return error;
1872                 /* Find the named attribute. */
1873                 bs->s.base = BHDR(bs->bh);
1874                 bs->s.first = BFIRST(bs->bh);
1875                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
1876                 bs->s.here = bs->s.first;
1877                 error = xattr_find_entry(inode, &bs->s.here, bs->s.end,
1878                                          i->name_index, i->name, 1);
1879                 if (error && error != -ENODATA)
1880                         return error;
1881                 bs->s.not_found = error;
1882         }
1883         return 0;
1884 }
1885
1886 static int
1887 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
1888                      struct ext4_xattr_info *i,
1889                      struct ext4_xattr_block_find *bs)
1890 {
1891         struct super_block *sb = inode->i_sb;
1892         struct buffer_head *new_bh = NULL;
1893         struct ext4_xattr_search s_copy = bs->s;
1894         struct ext4_xattr_search *s = &s_copy;
1895         struct mb_cache_entry *ce = NULL;
1896         int error = 0;
1897         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
1898         struct inode *ea_inode = NULL, *tmp_inode;
1899         size_t old_ea_inode_quota = 0;
1900         unsigned int ea_ino;
1901
1902 #define header(x) ((struct ext4_xattr_header *)(x))
1903
1904         /* If we need EA inode, prepare it before locking the buffer */
1905         if (i->value && i->in_inode) {
1906                 WARN_ON_ONCE(!i->value_len);
1907
1908                 ea_inode = ext4_xattr_inode_lookup_create(handle, inode,
1909                                         i->value, i->value_len);
1910                 if (IS_ERR(ea_inode)) {
1911                         error = PTR_ERR(ea_inode);
1912                         ea_inode = NULL;
1913                         goto cleanup;
1914                 }
1915         }
1916
1917         if (s->base) {
1918                 int offset = (char *)s->here - bs->bh->b_data;
1919
1920                 BUFFER_TRACE(bs->bh, "get_write_access");
1921                 error = ext4_journal_get_write_access(handle, sb, bs->bh,
1922                                                       EXT4_JTR_NONE);
1923                 if (error)
1924                         goto cleanup;
1925
1926                 lock_buffer(bs->bh);
1927
1928                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
1929                         __u32 hash = le32_to_cpu(BHDR(bs->bh)->h_hash);
1930
1931                         /*
1932                          * This must happen under buffer lock for
1933                          * ext4_xattr_block_set() to reliably detect modified
1934                          * block
1935                          */
1936                         if (ea_block_cache) {
1937                                 struct mb_cache_entry *oe;
1938
1939                                 oe = mb_cache_entry_delete_or_get(ea_block_cache,
1940                                         hash, bs->bh->b_blocknr);
1941                                 if (oe) {
1942                                         /*
1943                                          * Xattr block is getting reused. Leave
1944                                          * it alone.
1945                                          */
1946                                         mb_cache_entry_put(ea_block_cache, oe);
1947                                         goto clone_block;
1948                                 }
1949                         }
1950                         ea_bdebug(bs->bh, "modifying in-place");
1951                         error = ext4_xattr_set_entry(i, s, handle, inode,
1952                                              ea_inode, true /* is_block */);
1953                         ext4_xattr_block_csum_set(inode, bs->bh);
1954                         unlock_buffer(bs->bh);
1955                         if (error == -EFSCORRUPTED)
1956                                 goto bad_block;
1957                         if (!error)
1958                                 error = ext4_handle_dirty_metadata(handle,
1959                                                                    inode,
1960                                                                    bs->bh);
1961                         if (error)
1962                                 goto cleanup;
1963                         goto inserted;
1964                 }
1965 clone_block:
1966                 unlock_buffer(bs->bh);
1967                 ea_bdebug(bs->bh, "cloning");
1968                 s->base = kmemdup(BHDR(bs->bh), bs->bh->b_size, GFP_NOFS);
1969                 error = -ENOMEM;
1970                 if (s->base == NULL)
1971                         goto cleanup;
1972                 s->first = ENTRY(header(s->base)+1);
1973                 header(s->base)->h_refcount = cpu_to_le32(1);
1974                 s->here = ENTRY(s->base + offset);
1975                 s->end = s->base + bs->bh->b_size;
1976
1977                 /*
1978                  * If existing entry points to an xattr inode, we need
1979                  * to prevent ext4_xattr_set_entry() from decrementing
1980                  * ref count on it because the reference belongs to the
1981                  * original block. In this case, make the entry look
1982                  * like it has an empty value.
1983                  */
1984                 if (!s->not_found && s->here->e_value_inum) {
1985                         ea_ino = le32_to_cpu(s->here->e_value_inum);
1986                         error = ext4_xattr_inode_iget(inode, ea_ino,
1987                                       le32_to_cpu(s->here->e_hash),
1988                                       &tmp_inode);
1989                         if (error)
1990                                 goto cleanup;
1991
1992                         if (!ext4_test_inode_state(tmp_inode,
1993                                         EXT4_STATE_LUSTRE_EA_INODE)) {
1994                                 /*
1995                                  * Defer quota free call for previous
1996                                  * inode until success is guaranteed.
1997                                  */
1998                                 old_ea_inode_quota = le32_to_cpu(
1999                                                 s->here->e_value_size);
2000                         }
2001                         iput(tmp_inode);
2002
2003                         s->here->e_value_inum = 0;
2004                         s->here->e_value_size = 0;
2005                 }
2006         } else {
2007                 /* Allocate a buffer where we construct the new block. */
2008                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
2009                 error = -ENOMEM;
2010                 if (s->base == NULL)
2011                         goto cleanup;
2012                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
2013                 header(s->base)->h_blocks = cpu_to_le32(1);
2014                 header(s->base)->h_refcount = cpu_to_le32(1);
2015                 s->first = ENTRY(header(s->base)+1);
2016                 s->here = ENTRY(header(s->base)+1);
2017                 s->end = s->base + sb->s_blocksize;
2018         }
2019
2020         error = ext4_xattr_set_entry(i, s, handle, inode, ea_inode,
2021                                      true /* is_block */);
2022         if (error == -EFSCORRUPTED)
2023                 goto bad_block;
2024         if (error)
2025                 goto cleanup;
2026
2027 inserted:
2028         if (!IS_LAST_ENTRY(s->first)) {
2029                 new_bh = ext4_xattr_block_cache_find(inode, header(s->base), &ce);
2030                 if (IS_ERR(new_bh)) {
2031                         error = PTR_ERR(new_bh);
2032                         new_bh = NULL;
2033                         goto cleanup;
2034                 }
2035
2036                 if (new_bh) {
2037                         /* We found an identical block in the cache. */
2038                         if (new_bh == bs->bh)
2039                                 ea_bdebug(new_bh, "keeping");
2040                         else {
2041                                 u32 ref;
2042
2043 #ifdef EXT4_XATTR_DEBUG
2044                                 WARN_ON_ONCE(dquot_initialize_needed(inode));
2045 #endif
2046                                 /* The old block is released after updating
2047                                    the inode. */
2048                                 error = dquot_alloc_block(inode,
2049                                                 EXT4_C2B(EXT4_SB(sb), 1));
2050                                 if (error)
2051                                         goto cleanup;
2052                                 BUFFER_TRACE(new_bh, "get_write_access");
2053                                 error = ext4_journal_get_write_access(
2054                                                 handle, sb, new_bh,
2055                                                 EXT4_JTR_NONE);
2056                                 if (error)
2057                                         goto cleanup_dquot;
2058                                 lock_buffer(new_bh);
2059                                 /*
2060                                  * We have to be careful about races with
2061                                  * adding references to xattr block. Once we
2062                                  * hold buffer lock xattr block's state is
2063                                  * stable so we can check the additional
2064                                  * reference fits.
2065                                  */
2066                                 ref = le32_to_cpu(BHDR(new_bh)->h_refcount) + 1;
2067                                 if (ref > EXT4_XATTR_REFCOUNT_MAX) {
2068                                         /*
2069                                          * Undo everything and check mbcache
2070                                          * again.
2071                                          */
2072                                         unlock_buffer(new_bh);
2073                                         dquot_free_block(inode,
2074                                                          EXT4_C2B(EXT4_SB(sb),
2075                                                                   1));
2076                                         brelse(new_bh);
2077                                         mb_cache_entry_put(ea_block_cache, ce);
2078                                         ce = NULL;
2079                                         new_bh = NULL;
2080                                         goto inserted;
2081                                 }
2082                                 BHDR(new_bh)->h_refcount = cpu_to_le32(ref);
2083                                 if (ref == EXT4_XATTR_REFCOUNT_MAX)
2084                                         clear_bit(MBE_REUSABLE_B, &ce->e_flags);
2085                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
2086                                           ref);
2087                                 ext4_xattr_block_csum_set(inode, new_bh);
2088                                 unlock_buffer(new_bh);
2089                                 error = ext4_handle_dirty_metadata(handle,
2090                                                                    inode,
2091                                                                    new_bh);
2092                                 if (error)
2093                                         goto cleanup_dquot;
2094                         }
2095                         mb_cache_entry_touch(ea_block_cache, ce);
2096                         mb_cache_entry_put(ea_block_cache, ce);
2097                         ce = NULL;
2098                 } else if (bs->bh && s->base == bs->bh->b_data) {
2099                         /* We were modifying this block in-place. */
2100                         ea_bdebug(bs->bh, "keeping this block");
2101                         ext4_xattr_block_cache_insert(ea_block_cache, bs->bh);
2102                         new_bh = bs->bh;
2103                         get_bh(new_bh);
2104                 } else {
2105                         /* We need to allocate a new block */
2106                         ext4_fsblk_t goal, block;
2107
2108 #ifdef EXT4_XATTR_DEBUG
2109                         WARN_ON_ONCE(dquot_initialize_needed(inode));
2110 #endif
2111                         goal = ext4_group_first_block_no(sb,
2112                                                 EXT4_I(inode)->i_block_group);
2113                         block = ext4_new_meta_blocks(handle, inode, goal, 0,
2114                                                      NULL, &error);
2115                         if (error)
2116                                 goto cleanup;
2117
2118                         ea_idebug(inode, "creating block %llu",
2119                                   (unsigned long long)block);
2120
2121                         new_bh = sb_getblk(sb, block);
2122                         if (unlikely(!new_bh)) {
2123                                 error = -ENOMEM;
2124 getblk_failed:
2125                                 ext4_free_blocks(handle, inode, NULL, block, 1,
2126                                                  EXT4_FREE_BLOCKS_METADATA);
2127                                 goto cleanup;
2128                         }
2129                         error = ext4_xattr_inode_inc_ref_all(handle, inode,
2130                                                       ENTRY(header(s->base)+1));
2131                         if (error)
2132                                 goto getblk_failed;
2133                         if (ea_inode) {
2134                                 /* Drop the extra ref on ea_inode. */
2135                                 error = ext4_xattr_inode_dec_ref(handle,
2136                                                                  ea_inode);
2137                                 if (error)
2138                                         ext4_warning_inode(ea_inode,
2139                                                            "dec ref error=%d",
2140                                                            error);
2141                                 iput(ea_inode);
2142                                 ea_inode = NULL;
2143                         }
2144
2145                         lock_buffer(new_bh);
2146                         error = ext4_journal_get_create_access(handle, sb,
2147                                                         new_bh, EXT4_JTR_NONE);
2148                         if (error) {
2149                                 unlock_buffer(new_bh);
2150                                 error = -EIO;
2151                                 goto getblk_failed;
2152                         }
2153                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
2154                         ext4_xattr_block_csum_set(inode, new_bh);
2155                         set_buffer_uptodate(new_bh);
2156                         unlock_buffer(new_bh);
2157                         ext4_xattr_block_cache_insert(ea_block_cache, new_bh);
2158                         error = ext4_handle_dirty_metadata(handle, inode,
2159                                                            new_bh);
2160                         if (error)
2161                                 goto cleanup;
2162                 }
2163         }
2164
2165         if (old_ea_inode_quota)
2166                 ext4_xattr_inode_free_quota(inode, NULL, old_ea_inode_quota);
2167
2168         /* Update the inode. */
2169         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
2170
2171         /* Drop the previous xattr block. */
2172         if (bs->bh && bs->bh != new_bh) {
2173                 struct ext4_xattr_inode_array *ea_inode_array = NULL;
2174
2175                 ext4_xattr_release_block(handle, inode, bs->bh,
2176                                          &ea_inode_array,
2177                                          0 /* extra_credits */);
2178                 ext4_xattr_inode_array_free(ea_inode_array);
2179         }
2180         error = 0;
2181
2182 cleanup:
2183         if (ea_inode) {
2184                 if (error) {
2185                         int error2;
2186
2187                         error2 = ext4_xattr_inode_dec_ref(handle, ea_inode);
2188                         if (error2)
2189                                 ext4_warning_inode(ea_inode, "dec ref error=%d",
2190                                                    error2);
2191                         ext4_xattr_inode_free_quota(inode, ea_inode,
2192                                                     i_size_read(ea_inode));
2193                 }
2194                 iput(ea_inode);
2195         }
2196         if (ce)
2197                 mb_cache_entry_put(ea_block_cache, ce);
2198         brelse(new_bh);
2199         if (!(bs->bh && s->base == bs->bh->b_data))
2200                 kfree(s->base);
2201
2202         return error;
2203
2204 cleanup_dquot:
2205         dquot_free_block(inode, EXT4_C2B(EXT4_SB(sb), 1));
2206         goto cleanup;
2207
2208 bad_block:
2209         EXT4_ERROR_INODE(inode, "bad block %llu",
2210                          EXT4_I(inode)->i_file_acl);
2211         goto cleanup;
2212
2213 #undef header
2214 }
2215
2216 int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
2217                           struct ext4_xattr_ibody_find *is)
2218 {
2219         struct ext4_xattr_ibody_header *header;
2220         struct ext4_inode *raw_inode;
2221         int error;
2222
2223         if (!EXT4_INODE_HAS_XATTR_SPACE(inode))
2224                 return 0;
2225
2226         raw_inode = ext4_raw_inode(&is->iloc);
2227         header = IHDR(inode, raw_inode);
2228         is->s.base = is->s.first = IFIRST(header);
2229         is->s.here = is->s.first;
2230         is->s.end = ITAIL(inode, raw_inode);
2231         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
2232                 /* Find the named attribute. */
2233                 error = xattr_find_entry(inode, &is->s.here, is->s.end,
2234                                          i->name_index, i->name, 0);
2235                 if (error && error != -ENODATA)
2236                         return error;
2237                 is->s.not_found = error;
2238         }
2239         return 0;
2240 }
2241
2242 int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
2243                                 struct ext4_xattr_info *i,
2244                                 struct ext4_xattr_ibody_find *is)
2245 {
2246         struct ext4_xattr_ibody_header *header;
2247         struct ext4_xattr_search *s = &is->s;
2248         struct inode *ea_inode = NULL;
2249         int error;
2250
2251         if (!EXT4_INODE_HAS_XATTR_SPACE(inode))
2252                 return -ENOSPC;
2253
2254         /* If we need EA inode, prepare it before locking the buffer */
2255         if (i->value && i->in_inode) {
2256                 WARN_ON_ONCE(!i->value_len);
2257
2258                 ea_inode = ext4_xattr_inode_lookup_create(handle, inode,
2259                                         i->value, i->value_len);
2260                 if (IS_ERR(ea_inode))
2261                         return PTR_ERR(ea_inode);
2262         }
2263         error = ext4_xattr_set_entry(i, s, handle, inode, ea_inode,
2264                                      false /* is_block */);
2265         if (error) {
2266                 if (ea_inode) {
2267                         int error2;
2268
2269                         error2 = ext4_xattr_inode_dec_ref(handle, ea_inode);
2270                         if (error2)
2271                                 ext4_warning_inode(ea_inode, "dec ref error=%d",
2272                                                    error2);
2273
2274                         ext4_xattr_inode_free_quota(inode, ea_inode,
2275                                                     i_size_read(ea_inode));
2276                         iput(ea_inode);
2277                 }
2278                 return error;
2279         }
2280         header = IHDR(inode, ext4_raw_inode(&is->iloc));
2281         if (!IS_LAST_ENTRY(s->first)) {
2282                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
2283                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
2284         } else {
2285                 header->h_magic = cpu_to_le32(0);
2286                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
2287         }
2288         iput(ea_inode);
2289         return 0;
2290 }
2291
2292 static int ext4_xattr_value_same(struct ext4_xattr_search *s,
2293                                  struct ext4_xattr_info *i)
2294 {
2295         void *value;
2296
2297         /* When e_value_inum is set the value is stored externally. */
2298         if (s->here->e_value_inum)
2299                 return 0;
2300         if (le32_to_cpu(s->here->e_value_size) != i->value_len)
2301                 return 0;
2302         value = ((void *)s->base) + le16_to_cpu(s->here->e_value_offs);
2303         return !memcmp(value, i->value, i->value_len);
2304 }
2305
2306 static struct buffer_head *ext4_xattr_get_block(struct inode *inode)
2307 {
2308         struct buffer_head *bh;
2309         int error;
2310
2311         if (!EXT4_I(inode)->i_file_acl)
2312                 return NULL;
2313         bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
2314         if (IS_ERR(bh))
2315                 return bh;
2316         error = ext4_xattr_check_block(inode, bh);
2317         if (error) {
2318                 brelse(bh);
2319                 return ERR_PTR(error);
2320         }
2321         return bh;
2322 }
2323
2324 /*
2325  * ext4_xattr_set_handle()
2326  *
2327  * Create, replace or remove an extended attribute for this inode.  Value
2328  * is NULL to remove an existing extended attribute, and non-NULL to
2329  * either replace an existing extended attribute, or create a new extended
2330  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
2331  * specify that an extended attribute must exist and must not exist
2332  * previous to the call, respectively.
2333  *
2334  * Returns 0, or a negative error number on failure.
2335  */
2336 int
2337 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
2338                       const char *name, const void *value, size_t value_len,
2339                       int flags)
2340 {
2341         struct ext4_xattr_info i = {
2342                 .name_index = name_index,
2343                 .name = name,
2344                 .value = value,
2345                 .value_len = value_len,
2346                 .in_inode = 0,
2347         };
2348         struct ext4_xattr_ibody_find is = {
2349                 .s = { .not_found = -ENODATA, },
2350         };
2351         struct ext4_xattr_block_find bs = {
2352                 .s = { .not_found = -ENODATA, },
2353         };
2354         int no_expand;
2355         int error;
2356
2357         if (!name)
2358                 return -EINVAL;
2359         if (strlen(name) > 255)
2360                 return -ERANGE;
2361
2362         ext4_write_lock_xattr(inode, &no_expand);
2363
2364         /* Check journal credits under write lock. */
2365         if (ext4_handle_valid(handle)) {
2366                 struct buffer_head *bh;
2367                 int credits;
2368
2369                 bh = ext4_xattr_get_block(inode);
2370                 if (IS_ERR(bh)) {
2371                         error = PTR_ERR(bh);
2372                         goto cleanup;
2373                 }
2374
2375                 credits = __ext4_xattr_set_credits(inode->i_sb, inode, bh,
2376                                                    value_len,
2377                                                    flags & XATTR_CREATE);
2378                 brelse(bh);
2379
2380                 if (jbd2_handle_buffer_credits(handle) < credits) {
2381                         error = -ENOSPC;
2382                         goto cleanup;
2383                 }
2384                 WARN_ON_ONCE(!(current->flags & PF_MEMALLOC_NOFS));
2385         }
2386
2387         error = ext4_reserve_inode_write(handle, inode, &is.iloc);
2388         if (error)
2389                 goto cleanup;
2390
2391         if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) {
2392                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
2393                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
2394                 ext4_clear_inode_state(inode, EXT4_STATE_NEW);
2395         }
2396
2397         error = ext4_xattr_ibody_find(inode, &i, &is);
2398         if (error)
2399                 goto cleanup;
2400         if (is.s.not_found)
2401                 error = ext4_xattr_block_find(inode, &i, &bs);
2402         if (error)
2403                 goto cleanup;
2404         if (is.s.not_found && bs.s.not_found) {
2405                 error = -ENODATA;
2406                 if (flags & XATTR_REPLACE)
2407                         goto cleanup;
2408                 error = 0;
2409                 if (!value)
2410                         goto cleanup;
2411         } else {
2412                 error = -EEXIST;
2413                 if (flags & XATTR_CREATE)
2414                         goto cleanup;
2415         }
2416
2417         if (!value) {
2418                 if (!is.s.not_found)
2419                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
2420                 else if (!bs.s.not_found)
2421                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
2422         } else {
2423                 error = 0;
2424                 /* Xattr value did not change? Save us some work and bail out */
2425                 if (!is.s.not_found && ext4_xattr_value_same(&is.s, &i))
2426                         goto cleanup;
2427                 if (!bs.s.not_found && ext4_xattr_value_same(&bs.s, &i))
2428                         goto cleanup;
2429
2430                 if (ext4_has_feature_ea_inode(inode->i_sb) &&
2431                     (EXT4_XATTR_SIZE(i.value_len) >
2432                         EXT4_XATTR_MIN_LARGE_EA_SIZE(inode->i_sb->s_blocksize)))
2433                         i.in_inode = 1;
2434 retry_inode:
2435                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
2436                 if (!error && !bs.s.not_found) {
2437                         i.value = NULL;
2438                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
2439                 } else if (error == -ENOSPC) {
2440                         if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
2441                                 brelse(bs.bh);
2442                                 bs.bh = NULL;
2443                                 error = ext4_xattr_block_find(inode, &i, &bs);
2444                                 if (error)
2445                                         goto cleanup;
2446                         }
2447                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
2448                         if (!error && !is.s.not_found) {
2449                                 i.value = NULL;
2450                                 error = ext4_xattr_ibody_set(handle, inode, &i,
2451                                                              &is);
2452                         } else if (error == -ENOSPC) {
2453                                 /*
2454                                  * Xattr does not fit in the block, store at
2455                                  * external inode if possible.
2456                                  */
2457                                 if (ext4_has_feature_ea_inode(inode->i_sb) &&
2458                                     i.value_len && !i.in_inode) {
2459                                         i.in_inode = 1;
2460                                         goto retry_inode;
2461                                 }
2462                         }
2463                 }
2464         }
2465         if (!error) {
2466                 ext4_xattr_update_super_block(handle, inode->i_sb);
2467                 inode_set_ctime_current(inode);
2468                 inode_inc_iversion(inode);
2469                 if (!value)
2470                         no_expand = 0;
2471                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
2472                 /*
2473                  * The bh is consumed by ext4_mark_iloc_dirty, even with
2474                  * error != 0.
2475                  */
2476                 is.iloc.bh = NULL;
2477                 if (IS_SYNC(inode))
2478                         ext4_handle_sync(handle);
2479         }
2480         ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_XATTR, handle);
2481
2482 cleanup:
2483         brelse(is.iloc.bh);
2484         brelse(bs.bh);
2485         ext4_write_unlock_xattr(inode, &no_expand);
2486         return error;
2487 }
2488
2489 int ext4_xattr_set_credits(struct inode *inode, size_t value_len,
2490                            bool is_create, int *credits)
2491 {
2492         struct buffer_head *bh;
2493         int err;
2494
2495         *credits = 0;
2496
2497         if (!EXT4_SB(inode->i_sb)->s_journal)
2498                 return 0;
2499
2500         down_read(&EXT4_I(inode)->xattr_sem);
2501
2502         bh = ext4_xattr_get_block(inode);
2503         if (IS_ERR(bh)) {
2504                 err = PTR_ERR(bh);
2505         } else {
2506                 *credits = __ext4_xattr_set_credits(inode->i_sb, inode, bh,
2507                                                     value_len, is_create);
2508                 brelse(bh);
2509                 err = 0;
2510         }
2511
2512         up_read(&EXT4_I(inode)->xattr_sem);
2513         return err;
2514 }
2515
2516 /*
2517  * ext4_xattr_set()
2518  *
2519  * Like ext4_xattr_set_handle, but start from an inode. This extended
2520  * attribute modification is a filesystem transaction by itself.
2521  *
2522  * Returns 0, or a negative error number on failure.
2523  */
2524 int
2525 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
2526                const void *value, size_t value_len, int flags)
2527 {
2528         handle_t *handle;
2529         struct super_block *sb = inode->i_sb;
2530         int error, retries = 0;
2531         int credits;
2532
2533         error = dquot_initialize(inode);
2534         if (error)
2535                 return error;
2536
2537 retry:
2538         error = ext4_xattr_set_credits(inode, value_len, flags & XATTR_CREATE,
2539                                        &credits);
2540         if (error)
2541                 return error;
2542
2543         handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
2544         if (IS_ERR(handle)) {
2545                 error = PTR_ERR(handle);
2546         } else {
2547                 int error2;
2548
2549                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
2550                                               value, value_len, flags);
2551                 ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_XATTR,
2552                                         handle);
2553                 error2 = ext4_journal_stop(handle);
2554                 if (error == -ENOSPC &&
2555                     ext4_should_retry_alloc(sb, &retries))
2556                         goto retry;
2557                 if (error == 0)
2558                         error = error2;
2559         }
2560
2561         return error;
2562 }
2563
2564 /*
2565  * Shift the EA entries in the inode to create space for the increased
2566  * i_extra_isize.
2567  */
2568 static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
2569                                      int value_offs_shift, void *to,
2570                                      void *from, size_t n)
2571 {
2572         struct ext4_xattr_entry *last = entry;
2573         int new_offs;
2574
2575         /* We always shift xattr headers further thus offsets get lower */
2576         BUG_ON(value_offs_shift > 0);
2577
2578         /* Adjust the value offsets of the entries */
2579         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
2580                 if (!last->e_value_inum && last->e_value_size) {
2581                         new_offs = le16_to_cpu(last->e_value_offs) +
2582                                                         value_offs_shift;
2583                         last->e_value_offs = cpu_to_le16(new_offs);
2584                 }
2585         }
2586         /* Shift the entries by n bytes */
2587         memmove(to, from, n);
2588 }
2589
2590 /*
2591  * Move xattr pointed to by 'entry' from inode into external xattr block
2592  */
2593 static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode,
2594                                     struct ext4_inode *raw_inode,
2595                                     struct ext4_xattr_entry *entry)
2596 {
2597         struct ext4_xattr_ibody_find *is = NULL;
2598         struct ext4_xattr_block_find *bs = NULL;
2599         char *buffer = NULL, *b_entry_name = NULL;
2600         size_t value_size = le32_to_cpu(entry->e_value_size);
2601         struct ext4_xattr_info i = {
2602                 .value = NULL,
2603                 .value_len = 0,
2604                 .name_index = entry->e_name_index,
2605                 .in_inode = !!entry->e_value_inum,
2606         };
2607         struct ext4_xattr_ibody_header *header = IHDR(inode, raw_inode);
2608         int needs_kvfree = 0;
2609         int error;
2610
2611         is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
2612         bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
2613         b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
2614         if (!is || !bs || !b_entry_name) {
2615                 error = -ENOMEM;
2616                 goto out;
2617         }
2618
2619         is->s.not_found = -ENODATA;
2620         bs->s.not_found = -ENODATA;
2621         is->iloc.bh = NULL;
2622         bs->bh = NULL;
2623
2624         /* Save the entry name and the entry value */
2625         if (entry->e_value_inum) {
2626                 buffer = kvmalloc(value_size, GFP_NOFS);
2627                 if (!buffer) {
2628                         error = -ENOMEM;
2629                         goto out;
2630                 }
2631                 needs_kvfree = 1;
2632                 error = ext4_xattr_inode_get(inode, entry, buffer, value_size);
2633                 if (error)
2634                         goto out;
2635         } else {
2636                 size_t value_offs = le16_to_cpu(entry->e_value_offs);
2637                 buffer = (void *)IFIRST(header) + value_offs;
2638         }
2639
2640         memcpy(b_entry_name, entry->e_name, entry->e_name_len);
2641         b_entry_name[entry->e_name_len] = '\0';
2642         i.name = b_entry_name;
2643
2644         error = ext4_get_inode_loc(inode, &is->iloc);
2645         if (error)
2646                 goto out;
2647
2648         error = ext4_xattr_ibody_find(inode, &i, is);
2649         if (error)
2650                 goto out;
2651
2652         i.value = buffer;
2653         i.value_len = value_size;
2654         error = ext4_xattr_block_find(inode, &i, bs);
2655         if (error)
2656                 goto out;
2657
2658         /* Move ea entry from the inode into the block */
2659         error = ext4_xattr_block_set(handle, inode, &i, bs);
2660         if (error)
2661                 goto out;
2662
2663         /* Remove the chosen entry from the inode */
2664         i.value = NULL;
2665         i.value_len = 0;
2666         error = ext4_xattr_ibody_set(handle, inode, &i, is);
2667
2668 out:
2669         kfree(b_entry_name);
2670         if (needs_kvfree && buffer)
2671                 kvfree(buffer);
2672         if (is)
2673                 brelse(is->iloc.bh);
2674         if (bs)
2675                 brelse(bs->bh);
2676         kfree(is);
2677         kfree(bs);
2678
2679         return error;
2680 }
2681
2682 static int ext4_xattr_make_inode_space(handle_t *handle, struct inode *inode,
2683                                        struct ext4_inode *raw_inode,
2684                                        int isize_diff, size_t ifree,
2685                                        size_t bfree, int *total_ino)
2686 {
2687         struct ext4_xattr_ibody_header *header = IHDR(inode, raw_inode);
2688         struct ext4_xattr_entry *small_entry;
2689         struct ext4_xattr_entry *entry;
2690         struct ext4_xattr_entry *last;
2691         unsigned int entry_size;        /* EA entry size */
2692         unsigned int total_size;        /* EA entry size + value size */
2693         unsigned int min_total_size;
2694         int error;
2695
2696         while (isize_diff > ifree) {
2697                 entry = NULL;
2698                 small_entry = NULL;
2699                 min_total_size = ~0U;
2700                 last = IFIRST(header);
2701                 /* Find the entry best suited to be pushed into EA block */
2702                 for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
2703                         /* never move system.data out of the inode */
2704                         if ((last->e_name_len == 4) &&
2705                             (last->e_name_index == EXT4_XATTR_INDEX_SYSTEM) &&
2706                             !memcmp(last->e_name, "data", 4))
2707                                 continue;
2708                         total_size = EXT4_XATTR_LEN(last->e_name_len);
2709                         if (!last->e_value_inum)
2710                                 total_size += EXT4_XATTR_SIZE(
2711                                                le32_to_cpu(last->e_value_size));
2712                         if (total_size <= bfree &&
2713                             total_size < min_total_size) {
2714                                 if (total_size + ifree < isize_diff) {
2715                                         small_entry = last;
2716                                 } else {
2717                                         entry = last;
2718                                         min_total_size = total_size;
2719                                 }
2720                         }
2721                 }
2722
2723                 if (entry == NULL) {
2724                         if (small_entry == NULL)
2725                                 return -ENOSPC;
2726                         entry = small_entry;
2727                 }
2728
2729                 entry_size = EXT4_XATTR_LEN(entry->e_name_len);
2730                 total_size = entry_size;
2731                 if (!entry->e_value_inum)
2732                         total_size += EXT4_XATTR_SIZE(
2733                                               le32_to_cpu(entry->e_value_size));
2734                 error = ext4_xattr_move_to_block(handle, inode, raw_inode,
2735                                                  entry);
2736                 if (error)
2737                         return error;
2738
2739                 *total_ino -= entry_size;
2740                 ifree += total_size;
2741                 bfree -= total_size;
2742         }
2743
2744         return 0;
2745 }
2746
2747 /*
2748  * Expand an inode by new_extra_isize bytes when EAs are present.
2749  * Returns 0 on success or negative error number on failure.
2750  */
2751 int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
2752                                struct ext4_inode *raw_inode, handle_t *handle)
2753 {
2754         struct ext4_xattr_ibody_header *header;
2755         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
2756         static unsigned int mnt_count;
2757         size_t min_offs;
2758         size_t ifree, bfree;
2759         int total_ino;
2760         void *base, *end;
2761         int error = 0, tried_min_extra_isize = 0;
2762         int s_min_extra_isize = le16_to_cpu(sbi->s_es->s_min_extra_isize);
2763         int isize_diff; /* How much do we need to grow i_extra_isize */
2764
2765 retry:
2766         isize_diff = new_extra_isize - EXT4_I(inode)->i_extra_isize;
2767         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
2768                 return 0;
2769
2770         header = IHDR(inode, raw_inode);
2771
2772         /*
2773          * Check if enough free space is available in the inode to shift the
2774          * entries ahead by new_extra_isize.
2775          */
2776
2777         base = IFIRST(header);
2778         end = ITAIL(inode, raw_inode);
2779         min_offs = end - base;
2780         total_ino = sizeof(struct ext4_xattr_ibody_header) + sizeof(u32);
2781
2782         ifree = ext4_xattr_free_space(base, &min_offs, base, &total_ino);
2783         if (ifree >= isize_diff)
2784                 goto shift;
2785
2786         /*
2787          * Enough free space isn't available in the inode, check if
2788          * EA block can hold new_extra_isize bytes.
2789          */
2790         if (EXT4_I(inode)->i_file_acl) {
2791                 struct buffer_head *bh;
2792
2793                 bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
2794                 if (IS_ERR(bh)) {
2795                         error = PTR_ERR(bh);
2796                         goto cleanup;
2797                 }
2798                 error = ext4_xattr_check_block(inode, bh);
2799                 if (error) {
2800                         brelse(bh);
2801                         goto cleanup;
2802                 }
2803                 base = BHDR(bh);
2804                 end = bh->b_data + bh->b_size;
2805                 min_offs = end - base;
2806                 bfree = ext4_xattr_free_space(BFIRST(bh), &min_offs, base,
2807                                               NULL);
2808                 brelse(bh);
2809                 if (bfree + ifree < isize_diff) {
2810                         if (!tried_min_extra_isize && s_min_extra_isize) {
2811                                 tried_min_extra_isize++;
2812                                 new_extra_isize = s_min_extra_isize;
2813                                 goto retry;
2814                         }
2815                         error = -ENOSPC;
2816                         goto cleanup;
2817                 }
2818         } else {
2819                 bfree = inode->i_sb->s_blocksize;
2820         }
2821
2822         error = ext4_xattr_make_inode_space(handle, inode, raw_inode,
2823                                             isize_diff, ifree, bfree,
2824                                             &total_ino);
2825         if (error) {
2826                 if (error == -ENOSPC && !tried_min_extra_isize &&
2827                     s_min_extra_isize) {
2828                         tried_min_extra_isize++;
2829                         new_extra_isize = s_min_extra_isize;
2830                         goto retry;
2831                 }
2832                 goto cleanup;
2833         }
2834 shift:
2835         /* Adjust the offsets and shift the remaining entries ahead */
2836         ext4_xattr_shift_entries(IFIRST(header), EXT4_I(inode)->i_extra_isize
2837                         - new_extra_isize, (void *)raw_inode +
2838                         EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
2839                         (void *)header, total_ino);
2840         EXT4_I(inode)->i_extra_isize = new_extra_isize;
2841
2842         if (ext4_has_inline_data(inode))
2843                 error = ext4_find_inline_data_nolock(inode);
2844
2845 cleanup:
2846         if (error && (mnt_count != le16_to_cpu(sbi->s_es->s_mnt_count))) {
2847                 ext4_warning(inode->i_sb, "Unable to expand inode %lu. Delete some EAs or run e2fsck.",
2848                              inode->i_ino);
2849                 mnt_count = le16_to_cpu(sbi->s_es->s_mnt_count);
2850         }
2851         return error;
2852 }
2853
2854 #define EIA_INCR 16 /* must be 2^n */
2855 #define EIA_MASK (EIA_INCR - 1)
2856
2857 /* Add the large xattr @inode into @ea_inode_array for deferred iput().
2858  * If @ea_inode_array is new or full it will be grown and the old
2859  * contents copied over.
2860  */
2861 static int
2862 ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
2863                         struct inode *inode)
2864 {
2865         if (*ea_inode_array == NULL) {
2866                 /*
2867                  * Start with 15 inodes, so it fits into a power-of-two size.
2868                  */
2869                 (*ea_inode_array) = kmalloc(
2870                         struct_size(*ea_inode_array, inodes, EIA_MASK),
2871                         GFP_NOFS);
2872                 if (*ea_inode_array == NULL)
2873                         return -ENOMEM;
2874                 (*ea_inode_array)->count = 0;
2875         } else if (((*ea_inode_array)->count & EIA_MASK) == EIA_MASK) {
2876                 /* expand the array once all 15 + n * 16 slots are full */
2877                 struct ext4_xattr_inode_array *new_array = NULL;
2878
2879                 new_array = kmalloc(
2880                         struct_size(*ea_inode_array, inodes,
2881                                     (*ea_inode_array)->count + EIA_INCR),
2882                         GFP_NOFS);
2883                 if (new_array == NULL)
2884                         return -ENOMEM;
2885                 memcpy(new_array, *ea_inode_array,
2886                        struct_size(*ea_inode_array, inodes,
2887                                    (*ea_inode_array)->count));
2888                 kfree(*ea_inode_array);
2889                 *ea_inode_array = new_array;
2890         }
2891         (*ea_inode_array)->count++;
2892         (*ea_inode_array)->inodes[(*ea_inode_array)->count - 1] = inode;
2893         return 0;
2894 }
2895
2896 /*
2897  * ext4_xattr_delete_inode()
2898  *
2899  * Free extended attribute resources associated with this inode. Traverse
2900  * all entries and decrement reference on any xattr inodes associated with this
2901  * inode. This is called immediately before an inode is freed. We have exclusive
2902  * access to the inode. If an orphan inode is deleted it will also release its
2903  * references on xattr block and xattr inodes.
2904  */
2905 int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
2906                             struct ext4_xattr_inode_array **ea_inode_array,
2907                             int extra_credits)
2908 {
2909         struct buffer_head *bh = NULL;
2910         struct ext4_xattr_ibody_header *header;
2911         struct ext4_iloc iloc = { .bh = NULL };
2912         struct ext4_xattr_entry *entry;
2913         struct inode *ea_inode;
2914         int error;
2915
2916         error = ext4_journal_ensure_credits(handle, extra_credits,
2917                         ext4_free_metadata_revoke_credits(inode->i_sb, 1));
2918         if (error < 0) {
2919                 EXT4_ERROR_INODE(inode, "ensure credits (error %d)", error);
2920                 goto cleanup;
2921         }
2922
2923         if (ext4_has_feature_ea_inode(inode->i_sb) &&
2924             ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
2925
2926                 error = ext4_get_inode_loc(inode, &iloc);
2927                 if (error) {
2928                         EXT4_ERROR_INODE(inode, "inode loc (error %d)", error);
2929                         goto cleanup;
2930                 }
2931
2932                 error = ext4_journal_get_write_access(handle, inode->i_sb,
2933                                                 iloc.bh, EXT4_JTR_NONE);
2934                 if (error) {
2935                         EXT4_ERROR_INODE(inode, "write access (error %d)",
2936                                          error);
2937                         goto cleanup;
2938                 }
2939
2940                 header = IHDR(inode, ext4_raw_inode(&iloc));
2941                 if (header->h_magic == cpu_to_le32(EXT4_XATTR_MAGIC))
2942                         ext4_xattr_inode_dec_ref_all(handle, inode, iloc.bh,
2943                                                      IFIRST(header),
2944                                                      false /* block_csum */,
2945                                                      ea_inode_array,
2946                                                      extra_credits,
2947                                                      false /* skip_quota */);
2948         }
2949
2950         if (EXT4_I(inode)->i_file_acl) {
2951                 bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
2952                 if (IS_ERR(bh)) {
2953                         error = PTR_ERR(bh);
2954                         if (error == -EIO) {
2955                                 EXT4_ERROR_INODE_ERR(inode, EIO,
2956                                                      "block %llu read error",
2957                                                      EXT4_I(inode)->i_file_acl);
2958                         }
2959                         bh = NULL;
2960                         goto cleanup;
2961                 }
2962                 error = ext4_xattr_check_block(inode, bh);
2963                 if (error)
2964                         goto cleanup;
2965
2966                 if (ext4_has_feature_ea_inode(inode->i_sb)) {
2967                         for (entry = BFIRST(bh); !IS_LAST_ENTRY(entry);
2968                              entry = EXT4_XATTR_NEXT(entry)) {
2969                                 if (!entry->e_value_inum)
2970                                         continue;
2971                                 error = ext4_xattr_inode_iget(inode,
2972                                               le32_to_cpu(entry->e_value_inum),
2973                                               le32_to_cpu(entry->e_hash),
2974                                               &ea_inode);
2975                                 if (error)
2976                                         continue;
2977                                 ext4_xattr_inode_free_quota(inode, ea_inode,
2978                                               le32_to_cpu(entry->e_value_size));
2979                                 iput(ea_inode);
2980                         }
2981
2982                 }
2983
2984                 ext4_xattr_release_block(handle, inode, bh, ea_inode_array,
2985                                          extra_credits);
2986                 /*
2987                  * Update i_file_acl value in the same transaction that releases
2988                  * block.
2989                  */
2990                 EXT4_I(inode)->i_file_acl = 0;
2991                 error = ext4_mark_inode_dirty(handle, inode);
2992                 if (error) {
2993                         EXT4_ERROR_INODE(inode, "mark inode dirty (error %d)",
2994                                          error);
2995                         goto cleanup;
2996                 }
2997                 ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_XATTR, handle);
2998         }
2999         error = 0;
3000 cleanup:
3001         brelse(iloc.bh);
3002         brelse(bh);
3003         return error;
3004 }
3005
3006 void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *ea_inode_array)
3007 {
3008         int idx;
3009
3010         if (ea_inode_array == NULL)
3011                 return;
3012
3013         for (idx = 0; idx < ea_inode_array->count; ++idx)
3014                 iput(ea_inode_array->inodes[idx]);
3015         kfree(ea_inode_array);
3016 }
3017
3018 /*
3019  * ext4_xattr_block_cache_insert()
3020  *
3021  * Create a new entry in the extended attribute block cache, and insert
3022  * it unless such an entry is already in the cache.
3023  */
3024 static void
3025 ext4_xattr_block_cache_insert(struct mb_cache *ea_block_cache,
3026                               struct buffer_head *bh)
3027 {
3028         struct ext4_xattr_header *header = BHDR(bh);
3029         __u32 hash = le32_to_cpu(header->h_hash);
3030         int reusable = le32_to_cpu(header->h_refcount) <
3031                        EXT4_XATTR_REFCOUNT_MAX;
3032         int error;
3033
3034         if (!ea_block_cache)
3035                 return;
3036         error = mb_cache_entry_create(ea_block_cache, GFP_NOFS, hash,
3037                                       bh->b_blocknr, reusable);
3038         if (error) {
3039                 if (error == -EBUSY)
3040                         ea_bdebug(bh, "already in cache");
3041         } else
3042                 ea_bdebug(bh, "inserting [%x]", (int)hash);
3043 }
3044
3045 /*
3046  * ext4_xattr_cmp()
3047  *
3048  * Compare two extended attribute blocks for equality.
3049  *
3050  * Returns 0 if the blocks are equal, 1 if they differ.
3051  */
3052 static int
3053 ext4_xattr_cmp(struct ext4_xattr_header *header1,
3054                struct ext4_xattr_header *header2)
3055 {
3056         struct ext4_xattr_entry *entry1, *entry2;
3057
3058         entry1 = ENTRY(header1+1);
3059         entry2 = ENTRY(header2+1);
3060         while (!IS_LAST_ENTRY(entry1)) {
3061                 if (IS_LAST_ENTRY(entry2))
3062                         return 1;
3063                 if (entry1->e_hash != entry2->e_hash ||
3064                     entry1->e_name_index != entry2->e_name_index ||
3065                     entry1->e_name_len != entry2->e_name_len ||
3066                     entry1->e_value_size != entry2->e_value_size ||
3067                     entry1->e_value_inum != entry2->e_value_inum ||
3068                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
3069                         return 1;
3070                 if (!entry1->e_value_inum &&
3071                     memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
3072                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
3073                            le32_to_cpu(entry1->e_value_size)))
3074                         return 1;
3075
3076                 entry1 = EXT4_XATTR_NEXT(entry1);
3077                 entry2 = EXT4_XATTR_NEXT(entry2);
3078         }
3079         if (!IS_LAST_ENTRY(entry2))
3080                 return 1;
3081         return 0;
3082 }
3083
3084 /*
3085  * ext4_xattr_block_cache_find()
3086  *
3087  * Find an identical extended attribute block.
3088  *
3089  * Returns a pointer to the block found, or NULL if such a block was not
3090  * found, or an error pointer if an error occurred while reading ea block.
3091  */
3092 static struct buffer_head *
3093 ext4_xattr_block_cache_find(struct inode *inode,
3094                             struct ext4_xattr_header *header,
3095                             struct mb_cache_entry **pce)
3096 {
3097         __u32 hash = le32_to_cpu(header->h_hash);
3098         struct mb_cache_entry *ce;
3099         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
3100
3101         if (!ea_block_cache)
3102                 return NULL;
3103         if (!header->h_hash)
3104                 return NULL;  /* never share */
3105         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
3106         ce = mb_cache_entry_find_first(ea_block_cache, hash);
3107         while (ce) {
3108                 struct buffer_head *bh;
3109
3110                 bh = ext4_sb_bread(inode->i_sb, ce->e_value, REQ_PRIO);
3111                 if (IS_ERR(bh)) {
3112                         if (PTR_ERR(bh) != -ENOMEM)
3113                                 EXT4_ERROR_INODE(inode, "block %lu read error",
3114                                                  (unsigned long)ce->e_value);
3115                         mb_cache_entry_put(ea_block_cache, ce);
3116                         return bh;
3117                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
3118                         *pce = ce;
3119                         return bh;
3120                 }
3121                 brelse(bh);
3122                 ce = mb_cache_entry_find_next(ea_block_cache, ce);
3123         }
3124         return NULL;
3125 }
3126
3127 #define NAME_HASH_SHIFT 5
3128 #define VALUE_HASH_SHIFT 16
3129
3130 /*
3131  * ext4_xattr_hash_entry()
3132  *
3133  * Compute the hash of an extended attribute.
3134  */
3135 static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value,
3136                                     size_t value_count)
3137 {
3138         __u32 hash = 0;
3139
3140         while (name_len--) {
3141                 hash = (hash << NAME_HASH_SHIFT) ^
3142                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
3143                        (unsigned char)*name++;
3144         }
3145         while (value_count--) {
3146                 hash = (hash << VALUE_HASH_SHIFT) ^
3147                        (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
3148                        le32_to_cpu(*value++);
3149         }
3150         return cpu_to_le32(hash);
3151 }
3152
3153 /*
3154  * ext4_xattr_hash_entry_signed()
3155  *
3156  * Compute the hash of an extended attribute incorrectly.
3157  */
3158 static __le32 ext4_xattr_hash_entry_signed(char *name, size_t name_len, __le32 *value, size_t value_count)
3159 {
3160         __u32 hash = 0;
3161
3162         while (name_len--) {
3163                 hash = (hash << NAME_HASH_SHIFT) ^
3164                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
3165                        (signed char)*name++;
3166         }
3167         while (value_count--) {
3168                 hash = (hash << VALUE_HASH_SHIFT) ^
3169                        (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
3170                        le32_to_cpu(*value++);
3171         }
3172         return cpu_to_le32(hash);
3173 }
3174
3175 #undef NAME_HASH_SHIFT
3176 #undef VALUE_HASH_SHIFT
3177
3178 #define BLOCK_HASH_SHIFT 16
3179
3180 /*
3181  * ext4_xattr_rehash()
3182  *
3183  * Re-compute the extended attribute hash value after an entry has changed.
3184  */
3185 static void ext4_xattr_rehash(struct ext4_xattr_header *header)
3186 {
3187         struct ext4_xattr_entry *here;
3188         __u32 hash = 0;
3189
3190         here = ENTRY(header+1);
3191         while (!IS_LAST_ENTRY(here)) {
3192                 if (!here->e_hash) {
3193                         /* Block is not shared if an entry's hash value == 0 */
3194                         hash = 0;
3195                         break;
3196                 }
3197                 hash = (hash << BLOCK_HASH_SHIFT) ^
3198                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
3199                        le32_to_cpu(here->e_hash);
3200                 here = EXT4_XATTR_NEXT(here);
3201         }
3202         header->h_hash = cpu_to_le32(hash);
3203 }
3204
3205 #undef BLOCK_HASH_SHIFT
3206
3207 #define HASH_BUCKET_BITS        10
3208
3209 struct mb_cache *
3210 ext4_xattr_create_cache(void)
3211 {
3212         return mb_cache_create(HASH_BUCKET_BITS);
3213 }
3214
3215 void ext4_xattr_destroy_cache(struct mb_cache *cache)
3216 {
3217         if (cache)
3218                 mb_cache_destroy(cache);
3219 }
3220