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]  = &posix_acl_access_xattr_handler,
  92         [EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler,
  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 *ext4_xattr_handlers[] = {
 102         &ext4_xattr_user_handler,
 103         &ext4_xattr_trusted_handler,
 104 #ifdef CONFIG_EXT4_FS_POSIX_ACL
 105         &posix_acl_access_xattr_handler,
 106         &posix_acl_default_xattr_handler,
 107 #endif
 108 #ifdef CONFIG_EXT4_FS_SECURITY
 109         &ext4_xattr_security_handler,
 110 #endif
 111         &ext4_xattr_hurd_handler,
 112         NULL
 113 };
 114
 115 #define EA_BLOCK_CACHE(inode)   (((struct ext4_sb_info *) \
 116                                 inode->i_sb->s_fs_info)->s_ea_block_cache)
 117
 118 #define EA_INODE_CACHE(inode)   (((struct ext4_sb_info *) \
 119                                 inode->i_sb->s_fs_info)->s_ea_inode_cache)
 120
 121 static int
 122 ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
 123                         struct inode *inode);
 124
 125 #ifdef CONFIG_LOCKDEP
 126 void ext4_xattr_inode_set_class(struct inode *ea_inode)
 127 {
 128         lockdep_set_subclass(&ea_inode->i_rwsem, 1);
 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, sbi->s_csum_seed, (__u8 *)&dsk_block_nr,
 143                            sizeof(dsk_block_nr));
 144         csum = ext4_chksum(sbi, csum, (__u8 *)hdr, offset);
 145         csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, sizeof(dummy_csum));
 146         offset += sizeof(dummy_csum);
 147         csum = ext4_chksum(sbi, 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_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_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 struct xattr_handler *
 177 ext4_xattr_handler(int name_index)
 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         return handler;
 184 }
 185
 186 static int
 187 ext4_xattr_check_entries(struct ext4_xattr_entry *entry, void *end,
 188                          void *value_start)
 189 {
 190         struct ext4_xattr_entry *e = entry;
 191
 192         /* Find the end of the names list */
 193         while (!IS_LAST_ENTRY(e)) {
 194                 struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(e);
 195                 if ((void *)next >= end)
 196                         return -EFSCORRUPTED;
 197                 if (strnlen(e->e_name, e->e_name_len) != e->e_name_len)
 198                         return -EFSCORRUPTED;
 199                 e = next;
 200         }
 201
 202         /* Check the values */
 203         while (!IS_LAST_ENTRY(entry)) {
 204                 u32 size = le32_to_cpu(entry->e_value_size);
 205
 206                 if (size > EXT4_XATTR_SIZE_MAX)
 207                         return -EFSCORRUPTED;
 208
 209                 if (size != 0 && entry->e_value_inum == 0) {
 210                         u16 offs = le16_to_cpu(entry->e_value_offs);
 211                         void *value;
 212
 213                         /*
 214                          * The value cannot overlap the names, and the value
 215                          * with padding cannot extend beyond 'end'.  Check both
 216                          * the padded and unpadded sizes, since the size may
 217                          * overflow to 0 when adding padding.
 218                          */
 219                         if (offs > end - value_start)
 220                                 return -EFSCORRUPTED;
 221                         value = value_start + offs;
 222                         if (value < (void *)e + sizeof(u32) ||
 223                             size > end - value ||
 224                             EXT4_XATTR_SIZE(size) > end - value)
 225                                 return -EFSCORRUPTED;
 226                 }
 227                 entry = EXT4_XATTR_NEXT(entry);
 228         }
 229
 230         return 0;
 231 }
 232
 233 static inline int
 234 __ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh,
 235                          const char *function, unsigned int line)
 236 {
 237         int error = -EFSCORRUPTED;
 238
 239         if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
 240             BHDR(bh)->h_blocks != cpu_to_le32(1))
 241                 goto errout;
 242         if (buffer_verified(bh))
 243                 return 0;
 244
 245         error = -EFSBADCRC;
 246         if (!ext4_xattr_block_csum_verify(inode, bh))
 247                 goto errout;
 248         error = ext4_xattr_check_entries(BFIRST(bh), bh->b_data + bh->b_size,
 249                                          bh->b_data);
 250 errout:
 251         if (error)
 252                 __ext4_error_inode(inode, function, line, 0, -error,
 253                                    "corrupted xattr block %llu",
 254                                    (unsigned long long) bh->b_blocknr);
 255         else
 256                 set_buffer_verified(bh);
 257         return error;
 258 }
 259
 260 #define ext4_xattr_check_block(inode, bh) \
 261         __ext4_xattr_check_block((inode), (bh),  __func__, __LINE__)
 262
 263
 264 static int
 265 __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
 266                          void *end, const char *function, unsigned int line)
 267 {
 268         int error = -EFSCORRUPTED;
 269
 270         if (end - (void *)header < sizeof(*header) + sizeof(u32) ||
 271             (header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)))
 272                 goto errout;
 273         error = ext4_xattr_check_entries(IFIRST(header), end, IFIRST(header));
 274 errout:
 275         if (error)
 276                 __ext4_error_inode(inode, function, line, 0, -error,
 277                                    "corrupted in-inode xattr");
 278         return error;
 279 }
 280
 281 #define xattr_check_inode(inode, header, end) \
 282         __xattr_check_inode((inode), (header), (end), __func__, __LINE__)
 283
 284 static int
 285 xattr_find_entry(struct inode *inode, struct ext4_xattr_entry **pentry,
 286                  void *end, int name_index, const char *name, int sorted)
 287 {
 288         struct ext4_xattr_entry *entry, *next;
 289         size_t name_len;
 290         int cmp = 1;
 291
 292         if (name == NULL)
 293                 return -EINVAL;
 294         name_len = strlen(name);
 295         for (entry = *pentry; !IS_LAST_ENTRY(entry); entry = next) {
 296                 next = EXT4_XATTR_NEXT(entry);
 297                 if ((void *) next >= end) {
 298                         EXT4_ERROR_INODE(inode, "corrupted xattr entries");
 299                         return -EFSCORRUPTED;
 300                 }
 301                 cmp = name_index - entry->e_name_index;
 302                 if (!cmp)
 303                         cmp = name_len - entry->e_name_len;
 304                 if (!cmp)
 305                         cmp = memcmp(name, entry->e_name, name_len);
 306                 if (cmp <= 0 && (sorted || cmp == 0))
 307                         break;
 308         }
 309         *pentry = entry;
 310         return cmp ? -ENODATA : 0;
 311 }
 312
 313 static u32
 314 ext4_xattr_inode_hash(struct ext4_sb_info *sbi, const void *buffer, size_t size)
 315 {
 316         return ext4_chksum(sbi, sbi->s_csum_seed, buffer, size);
 317 }
 318
 319 static u64 ext4_xattr_inode_get_ref(struct inode *ea_inode)
 320 {
 321         return ((u64)ea_inode->i_ctime.tv_sec << 32) |
 322                 (u32) inode_peek_iversion_raw(ea_inode);
 323 }
 324
 325 static void ext4_xattr_inode_set_ref(struct inode *ea_inode, u64 ref_count)
 326 {
 327         ea_inode->i_ctime.tv_sec = (u32)(ref_count >> 32);
 328         inode_set_iversion_raw(ea_inode, ref_count & 0xffffffff);
 329 }
 330
 331 static u32 ext4_xattr_inode_get_hash(struct inode *ea_inode)
 332 {
 333         return (u32)ea_inode->i_atime.tv_sec;
 334 }
 335
 336 static void ext4_xattr_inode_set_hash(struct inode *ea_inode, u32 hash)
 337 {
 338         ea_inode->i_atime.tv_sec = hash;
 339 }
 340
 341 /*
 342  * Read the EA value from an inode.
 343  */
 344 static int ext4_xattr_inode_read(struct inode *ea_inode, void *buf, size_t size)
 345 {
 346         int blocksize = 1 << ea_inode->i_blkbits;
 347         int bh_count = (size + blocksize - 1) >> ea_inode->i_blkbits;
 348         int tail_size = (size % blocksize) ?: blocksize;
 349         struct buffer_head *bhs_inline[8];
 350         struct buffer_head **bhs = bhs_inline;
 351         int i, ret;
 352
 353         if (bh_count > ARRAY_SIZE(bhs_inline)) {
 354                 bhs = kmalloc_array(bh_count, sizeof(*bhs), GFP_NOFS);
 355                 if (!bhs)
 356                         return -ENOMEM;
 357         }
 358
 359         ret = ext4_bread_batch(ea_inode, 0 /* block */, bh_count,
 360                                true /* wait */, bhs);
 361         if (ret)
 362                 goto free_bhs;
 363
 364         for (i = 0; i < bh_count; i++) {
 365                 /* There shouldn't be any holes in ea_inode. */
 366                 if (!bhs[i]) {
 367                         ret = -EFSCORRUPTED;
 368                         goto put_bhs;
 369                 }
 370                 memcpy((char *)buf + blocksize * i, bhs[i]->b_data,
 371                        i < bh_count - 1 ? blocksize : tail_size);
 372         }
 373         ret = 0;
 374 put_bhs:
 375         for (i = 0; i < bh_count; i++)
 376                 brelse(bhs[i]);
 377 free_bhs:
 378         if (bhs != bhs_inline)
 379                 kfree(bhs);
 380         return ret;
 381 }
 382
 383 #define EXT4_XATTR_INODE_GET_PARENT(inode) ((__u32)(inode)->i_mtime.tv_sec)
 384
 385 static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino,
 386                                  u32 ea_inode_hash, struct inode **ea_inode)
 387 {
 388         struct inode *inode;
 389         int err;
 390
 391         inode = ext4_iget(parent->i_sb, ea_ino, EXT4_IGET_NORMAL);
 392         if (IS_ERR(inode)) {
 393                 err = PTR_ERR(inode);
 394                 ext4_error(parent->i_sb,
 395                            "error while reading EA inode %lu err=%d", ea_ino,
 396                            err);
 397                 return err;
 398         }
 399
 400         if (is_bad_inode(inode)) {
 401                 ext4_error(parent->i_sb,
 402                            "error while reading EA inode %lu is_bad_inode",
 403                            ea_ino);
 404                 err = -EIO;
 405                 goto error;
 406         }
 407
 408         if (!(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)) {
 409                 ext4_error(parent->i_sb,
 410                            "EA inode %lu does not have EXT4_EA_INODE_FL flag",
 411                             ea_ino);
 412                 err = -EINVAL;
 413                 goto error;
 414         }
 415
 416         ext4_xattr_inode_set_class(inode);
 417
 418         /*
 419          * Check whether this is an old Lustre-style xattr inode. Lustre
 420          * implementation does not have hash validation, rather it has a
 421          * backpointer from ea_inode to the parent inode.
 422          */
 423         if (ea_inode_hash != ext4_xattr_inode_get_hash(inode) &&
 424             EXT4_XATTR_INODE_GET_PARENT(inode) == parent->i_ino &&
 425             inode->i_generation == parent->i_generation) {
 426                 ext4_set_inode_state(inode, EXT4_STATE_LUSTRE_EA_INODE);
 427                 ext4_xattr_inode_set_ref(inode, 1);
 428         } else {
 429                 inode_lock(inode);
 430                 inode->i_flags |= S_NOQUOTA;
 431                 inode_unlock(inode);
 432         }
 433
 434         *ea_inode = inode;
 435         return 0;
 436 error:
 437         iput(inode);
 438         return err;
 439 }
 440
 441 /* Remove entry from mbcache when EA inode is getting evicted */
 442 void ext4_evict_ea_inode(struct inode *inode)
 443 {
 444         struct mb_cache_entry *oe;
 445
 446         if (!EA_INODE_CACHE(inode))
 447                 return;
 448         /* Wait for entry to get unused so that we can remove it */
 449         while ((oe = mb_cache_entry_delete_or_get(EA_INODE_CACHE(inode),
 450                         ext4_xattr_inode_get_hash(inode), inode->i_ino))) {
 451                 mb_cache_entry_wait_unused(oe);
 452                 mb_cache_entry_put(EA_INODE_CACHE(inode), oe);
 453         }
 454 }
 455
 456 static int
 457 ext4_xattr_inode_verify_hashes(struct inode *ea_inode,
 458                                struct ext4_xattr_entry *entry, void *buffer,
 459                                size_t size)
 460 {
 461         u32 hash;
 462
 463         /* Verify stored hash matches calculated hash. */
 464         hash = ext4_xattr_inode_hash(EXT4_SB(ea_inode->i_sb), buffer, size);
 465         if (hash != ext4_xattr_inode_get_hash(ea_inode))
 466                 return -EFSCORRUPTED;
 467
 468         if (entry) {
 469                 __le32 e_hash, tmp_data;
 470
 471                 /* Verify entry hash. */
 472                 tmp_data = cpu_to_le32(hash);
 473                 e_hash = ext4_xattr_hash_entry(entry->e_name, entry->e_name_len,
 474                                                &tmp_data, 1);
 475                 /* All good? */
 476                 if (e_hash == entry->e_hash)
 477                         return 0;
 478
 479                 /*
 480                  * Not good. Maybe the entry hash was calculated
 481                  * using the buggy signed char version?
 482                  */
 483                 e_hash = ext4_xattr_hash_entry_signed(entry->e_name, entry->e_name_len,
 484                                                         &tmp_data, 1);
 485                 /* Still no match - bad */
 486                 if (e_hash != entry->e_hash)
 487                         return -EFSCORRUPTED;
 488
 489                 /* Let people know about old hash */
 490                 pr_warn_once("ext4: filesystem with signed xattr name hash");
 491         }
 492         return 0;
 493 }
 494
 495 /*
 496  * Read xattr value from the EA inode.
 497  */
 498 static int
 499 ext4_xattr_inode_get(struct inode *inode, struct ext4_xattr_entry *entry,
 500                      void *buffer, size_t size)
 501 {
 502         struct mb_cache *ea_inode_cache = EA_INODE_CACHE(inode);
 503         struct inode *ea_inode;
 504         int err;
 505
 506         err = ext4_xattr_inode_iget(inode, le32_to_cpu(entry->e_value_inum),
 507                                     le32_to_cpu(entry->e_hash), &ea_inode);
 508         if (err) {
 509                 ea_inode = NULL;
 510                 goto out;
 511         }
 512
 513         if (i_size_read(ea_inode) != size) {
 514                 ext4_warning_inode(ea_inode,
 515                                    "ea_inode file size=%llu entry size=%zu",
 516                                    i_size_read(ea_inode), size);
 517                 err = -EFSCORRUPTED;
 518                 goto out;
 519         }
 520
 521         err = ext4_xattr_inode_read(ea_inode, buffer, size);
 522         if (err)
 523                 goto out;
 524
 525         if (!ext4_test_inode_state(ea_inode, EXT4_STATE_LUSTRE_EA_INODE)) {
 526                 err = ext4_xattr_inode_verify_hashes(ea_inode, entry, buffer,
 527                                                      size);
 528                 if (err) {
 529                         ext4_warning_inode(ea_inode,
 530                                            "EA inode hash validation failed");
 531                         goto out;
 532                 }
 533
 534                 if (ea_inode_cache)
 535                         mb_cache_entry_create(ea_inode_cache, GFP_NOFS,
 536                                         ext4_xattr_inode_get_hash(ea_inode),
 537                                         ea_inode->i_ino, true /* reusable */);
 538         }
 539 out:
 540         iput(ea_inode);
 541         return err;
 542 }
 543
 544 static int
 545 ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
 546                      void *buffer, size_t buffer_size)
 547 {
 548         struct buffer_head *bh = NULL;
 549         struct ext4_xattr_entry *entry;
 550         size_t size;
 551         void *end;
 552         int error;
 553         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
 554
 555         ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
 556                   name_index, name, buffer, (long)buffer_size);
 557
 558         if (!EXT4_I(inode)->i_file_acl)
 559                 return -ENODATA;
 560         ea_idebug(inode, "reading block %llu",
 561                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 562         bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
 563         if (IS_ERR(bh))
 564                 return PTR_ERR(bh);
 565         ea_bdebug(bh, "b_count=%d, refcount=%d",
 566                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 567         error = ext4_xattr_check_block(inode, bh);
 568         if (error)
 569                 goto cleanup;
 570         ext4_xattr_block_cache_insert(ea_block_cache, bh);
 571         entry = BFIRST(bh);
 572         end = bh->b_data + bh->b_size;
 573         error = xattr_find_entry(inode, &entry, end, name_index, name, 1);
 574         if (error)
 575                 goto cleanup;
 576         size = le32_to_cpu(entry->e_value_size);
 577         error = -ERANGE;
 578         if (unlikely(size > EXT4_XATTR_SIZE_MAX))
 579                 goto cleanup;
 580         if (buffer) {
 581                 if (size > buffer_size)
 582                         goto cleanup;
 583                 if (entry->e_value_inum) {
 584                         error = ext4_xattr_inode_get(inode, entry, buffer,
 585                                                      size);
 586                         if (error)
 587                                 goto cleanup;
 588                 } else {
 589                         u16 offset = le16_to_cpu(entry->e_value_offs);
 590                         void *p = bh->b_data + offset;
 591
 592                         if (unlikely(p + size > end))
 593                                 goto cleanup;
 594                         memcpy(buffer, p, size);
 595                 }
 596         }
 597         error = size;
 598
 599 cleanup:
 600         brelse(bh);
 601         return error;
 602 }
 603
 604 int
 605 ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
 606                      void *buffer, size_t buffer_size)
 607 {
 608         struct ext4_xattr_ibody_header *header;
 609         struct ext4_xattr_entry *entry;
 610         struct ext4_inode *raw_inode;
 611         struct ext4_iloc iloc;
 612         size_t size;
 613         void *end;
 614         int error;
 615
 616         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 617                 return -ENODATA;
 618         error = ext4_get_inode_loc(inode, &iloc);
 619         if (error)
 620                 return error;
 621         raw_inode = ext4_raw_inode(&iloc);
 622         header = IHDR(inode, raw_inode);
 623         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 624         error = xattr_check_inode(inode, header, end);
 625         if (error)
 626                 goto cleanup;
 627         entry = IFIRST(header);
 628         error = xattr_find_entry(inode, &entry, end, name_index, name, 0);
 629         if (error)
 630                 goto cleanup;
 631         size = le32_to_cpu(entry->e_value_size);
 632         error = -ERANGE;
 633         if (unlikely(size > EXT4_XATTR_SIZE_MAX))
 634                 goto cleanup;
 635         if (buffer) {
 636                 if (size > buffer_size)
 637                         goto cleanup;
 638                 if (entry->e_value_inum) {
 639                         error = ext4_xattr_inode_get(inode, entry, buffer,
 640                                                      size);
 641                         if (error)
 642                                 goto cleanup;
 643                 } else {
 644                         u16 offset = le16_to_cpu(entry->e_value_offs);
 645                         void *p = (void *)IFIRST(header) + offset;
 646
 647                         if (unlikely(p + size > end))
 648                                 goto cleanup;
 649                         memcpy(buffer, p, size);
 650                 }
 651         }
 652         error = size;
 653
 654 cleanup:
 655         brelse(iloc.bh);
 656         return error;
 657 }
 658
 659 /*
 660  * ext4_xattr_get()
 661  *
 662  * Copy an extended attribute into the buffer
 663  * provided, or compute the buffer size required.
 664  * Buffer is NULL to compute the size of the buffer required.
 665  *
 666  * Returns a negative error number on failure, or the number of bytes
 667  * used / required on success.
 668  */
 669 int
 670 ext4_xattr_get(struct inode *inode, int name_index, const char *name,
 671                void *buffer, size_t buffer_size)
 672 {
 673         int error;
 674
 675         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 676                 return -EIO;
 677
 678         if (strlen(name) > 255)
 679                 return -ERANGE;
 680
 681         down_read(&EXT4_I(inode)->xattr_sem);
 682         error = ext4_xattr_ibody_get(inode, name_index, name, buffer,
 683                                      buffer_size);
 684         if (error == -ENODATA)
 685                 error = ext4_xattr_block_get(inode, name_index, name, buffer,
 686                                              buffer_size);
 687         up_read(&EXT4_I(inode)->xattr_sem);
 688         return error;
 689 }
 690
 691 static int
 692 ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,
 693                         char *buffer, size_t buffer_size)
 694 {
 695         size_t rest = buffer_size;
 696
 697         for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
 698                 const struct xattr_handler *handler =
 699                         ext4_xattr_handler(entry->e_name_index);
 700
 701                 if (handler && (!handler->list || handler->list(dentry))) {
 702                         const char *prefix = handler->prefix ?: handler->name;
 703                         size_t prefix_len = strlen(prefix);
 704                         size_t size = prefix_len + entry->e_name_len + 1;
 705
 706                         if (buffer) {
 707                                 if (size > rest)
 708                                         return -ERANGE;
 709                                 memcpy(buffer, prefix, prefix_len);
 710                                 buffer += prefix_len;
 711                                 memcpy(buffer, entry->e_name, entry->e_name_len);
 712                                 buffer += entry->e_name_len;
 713                                 *buffer++ = 0;
 714                         }
 715                         rest -= size;
 716                 }
 717         }
 718         return buffer_size - rest;  /* total size */
 719 }
 720
 721 static int
 722 ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 723 {
 724         struct inode *inode = d_inode(dentry);
 725         struct buffer_head *bh = NULL;
 726         int error;
 727
 728         ea_idebug(inode, "buffer=%p, buffer_size=%ld",
 729                   buffer, (long)buffer_size);
 730
 731         if (!EXT4_I(inode)->i_file_acl)
 732                 return 0;
 733         ea_idebug(inode, "reading block %llu",
 734                   (unsigned long long)EXT4_I(inode)->i_file_acl);
 735         bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
 736         if (IS_ERR(bh))
 737                 return PTR_ERR(bh);
 738         ea_bdebug(bh, "b_count=%d, refcount=%d",
 739                 atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
 740         error = ext4_xattr_check_block(inode, bh);
 741         if (error)
 742                 goto cleanup;
 743         ext4_xattr_block_cache_insert(EA_BLOCK_CACHE(inode), bh);
 744         error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer,
 745                                         buffer_size);
 746 cleanup:
 747         brelse(bh);
 748         return error;
 749 }
 750
 751 static int
 752 ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
 753 {
 754         struct inode *inode = d_inode(dentry);
 755         struct ext4_xattr_ibody_header *header;
 756         struct ext4_inode *raw_inode;
 757         struct ext4_iloc iloc;
 758         void *end;
 759         int error;
 760
 761         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))
 762                 return 0;
 763         error = ext4_get_inode_loc(inode, &iloc);
 764         if (error)
 765                 return error;
 766         raw_inode = ext4_raw_inode(&iloc);
 767         header = IHDR(inode, raw_inode);
 768         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 769         error = xattr_check_inode(inode, header, end);
 770         if (error)
 771                 goto cleanup;
 772         error = ext4_xattr_list_entries(dentry, IFIRST(header),
 773                                         buffer, buffer_size);
 774
 775 cleanup:
 776         brelse(iloc.bh);
 777         return error;
 778 }
 779
 780 /*
 781  * Inode operation listxattr()
 782  *
 783  * d_inode(dentry)->i_rwsem: don't care
 784  *
 785  * Copy a list of attribute names into the buffer
 786  * provided, or compute the buffer size required.
 787  * Buffer is NULL to compute the size of the buffer required.
 788  *
 789  * Returns a negative error number on failure, or the number of bytes
 790  * used / required on success.
 791  */
 792 ssize_t
 793 ext4_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 794 {
 795         int ret, ret2;
 796
 797         down_read(&EXT4_I(d_inode(dentry))->xattr_sem);
 798         ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size);
 799         if (ret < 0)
 800                 goto errout;
 801         if (buffer) {
 802                 buffer += ret;
 803                 buffer_size -= ret;
 804         }
 805         ret = ext4_xattr_block_list(dentry, buffer, buffer_size);
 806         if (ret < 0)
 807                 goto errout;
 808         ret += ret2;
 809 errout:
 810         up_read(&EXT4_I(d_inode(dentry))->xattr_sem);
 811         return ret;
 812 }
 813
 814 /*
 815  * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 816  * not set, set it.
 817  */
 818 static void ext4_xattr_update_super_block(handle_t *handle,
 819                                           struct super_block *sb)
 820 {
 821         if (ext4_has_feature_xattr(sb))
 822                 return;
 823
 824         BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get_write_access");
 825         if (ext4_journal_get_write_access(handle, sb, EXT4_SB(sb)->s_sbh,
 826                                           EXT4_JTR_NONE) == 0) {
 827                 lock_buffer(EXT4_SB(sb)->s_sbh);
 828                 ext4_set_feature_xattr(sb);
 829                 ext4_superblock_csum_set(sb);
 830                 unlock_buffer(EXT4_SB(sb)->s_sbh);
 831                 ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
 832         }
 833 }
 834
 835 int ext4_get_inode_usage(struct inode *inode, qsize_t *usage)
 836 {
 837         struct ext4_iloc iloc = { .bh = NULL };
 838         struct buffer_head *bh = NULL;
 839         struct ext4_inode *raw_inode;
 840         struct ext4_xattr_ibody_header *header;
 841         struct ext4_xattr_entry *entry;
 842         qsize_t ea_inode_refs = 0;
 843         void *end;
 844         int ret;
 845
 846         lockdep_assert_held_read(&EXT4_I(inode)->xattr_sem);
 847
 848         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
 849                 ret = ext4_get_inode_loc(inode, &iloc);
 850                 if (ret)
 851                         goto out;
 852                 raw_inode = ext4_raw_inode(&iloc);
 853                 header = IHDR(inode, raw_inode);
 854                 end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
 855                 ret = xattr_check_inode(inode, header, end);
 856                 if (ret)
 857                         goto out;
 858
 859                 for (entry = IFIRST(header); !IS_LAST_ENTRY(entry);
 860                      entry = EXT4_XATTR_NEXT(entry))
 861                         if (entry->e_value_inum)
 862                                 ea_inode_refs++;
 863         }
 864
 865         if (EXT4_I(inode)->i_file_acl) {
 866                 bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
 867                 if (IS_ERR(bh)) {
 868                         ret = PTR_ERR(bh);
 869                         bh = NULL;
 870                         goto out;
 871                 }
 872
 873                 ret = ext4_xattr_check_block(inode, bh);
 874                 if (ret)
 875                         goto out;
 876
 877                 for (entry = BFIRST(bh); !IS_LAST_ENTRY(entry);
 878                      entry = EXT4_XATTR_NEXT(entry))
 879                         if (entry->e_value_inum)
 880                                 ea_inode_refs++;
 881         }
 882         *usage = ea_inode_refs + 1;
 883         ret = 0;
 884 out:
 885         brelse(iloc.bh);
 886         brelse(bh);
 887         return ret;
 888 }
 889
 890 static inline size_t round_up_cluster(struct inode *inode, size_t length)
 891 {
 892         struct super_block *sb = inode->i_sb;
 893         size_t cluster_size = 1 << (EXT4_SB(sb)->s_cluster_bits +
 894                                     inode->i_blkbits);
 895         size_t mask = ~(cluster_size - 1);
 896
 897         return (length + cluster_size - 1) & mask;
 898 }
 899
 900 static int ext4_xattr_inode_alloc_quota(struct inode *inode, size_t len)
 901 {
 902         int err;
 903
 904         err = dquot_alloc_inode(inode);
 905         if (err)
 906                 return err;
 907         err = dquot_alloc_space_nodirty(inode, round_up_cluster(inode, len));
 908         if (err)
 909                 dquot_free_inode(inode);
 910         return err;
 911 }
 912
 913 static void ext4_xattr_inode_free_quota(struct inode *parent,
 914                                         struct inode *ea_inode,
 915                                         size_t len)
 916 {
 917         if (ea_inode &&
 918             ext4_test_inode_state(ea_inode, EXT4_STATE_LUSTRE_EA_INODE))
 919                 return;
 920         dquot_free_space_nodirty(parent, round_up_cluster(parent, len));
 921         dquot_free_inode(parent);
 922 }
 923
 924 int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode,
 925                              struct buffer_head *block_bh, size_t value_len,
 926                              bool is_create)
 927 {
 928         int credits;
 929         int blocks;
 930
 931         /*
 932          * 1) Owner inode update
 933          * 2) Ref count update on old xattr block
 934          * 3) new xattr block
 935          * 4) block bitmap update for new xattr block
 936          * 5) group descriptor for new xattr block
 937          * 6) block bitmap update for old xattr block
 938          * 7) group descriptor for old block
 939          *
 940          * 6 & 7 can happen if we have two racing threads T_a and T_b
 941          * which are each trying to set an xattr on inodes I_a and I_b
 942          * which were both initially sharing an xattr block.
 943          */
 944         credits = 7;
 945
 946         /* Quota updates. */
 947         credits += EXT4_MAXQUOTAS_TRANS_BLOCKS(sb);
 948
 949         /*
 950          * In case of inline data, we may push out the data to a block,
 951          * so we need to reserve credits for this eventuality
 952          */
 953         if (inode && ext4_has_inline_data(inode))
 954                 credits += ext4_writepage_trans_blocks(inode) + 1;
 955
 956         /* We are done if ea_inode feature is not enabled. */
 957         if (!ext4_has_feature_ea_inode(sb))
 958                 return credits;
 959
 960         /* New ea_inode, inode map, block bitmap, group descriptor. */
 961         credits += 4;
 962
 963         /* Data blocks. */
 964         blocks = (value_len + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
 965
 966         /* Indirection block or one level of extent tree. */
 967         blocks += 1;
 968
 969         /* Block bitmap and group descriptor updates for each block. */
 970         credits += blocks * 2;
 971
 972         /* Blocks themselves. */
 973         credits += blocks;
 974
 975         if (!is_create) {
 976                 /* Dereference ea_inode holding old xattr value.
 977                  * Old ea_inode, inode map, block bitmap, group descriptor.
 978                  */
 979                 credits += 4;
 980
 981                 /* Data blocks for old ea_inode. */
 982                 blocks = XATTR_SIZE_MAX >> sb->s_blocksize_bits;
 983
 984                 /* Indirection block or one level of extent tree for old
 985                  * ea_inode.
 986                  */
 987                 blocks += 1;
 988
 989                 /* Block bitmap and group descriptor updates for each block. */
 990                 credits += blocks * 2;
 991         }
 992
 993         /* We may need to clone the existing xattr block in which case we need
 994          * to increment ref counts for existing ea_inodes referenced by it.
 995          */
 996         if (block_bh) {
 997                 struct ext4_xattr_entry *entry = BFIRST(block_bh);
 998
 999                 for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry))
1000                         if (entry->e_value_inum)
1001                                 /* Ref count update on ea_inode. */
1002                                 credits += 1;
1003         }
1004         return credits;
1005 }
1006
1007 static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode,
1008                                        int ref_change)
1009 {
1010         struct ext4_iloc iloc;
1011         s64 ref_count;
1012         int ret;
1013
1014         inode_lock(ea_inode);
1015
1016         ret = ext4_reserve_inode_write(handle, ea_inode, &iloc);
1017         if (ret)
1018                 goto out;
1019
1020         ref_count = ext4_xattr_inode_get_ref(ea_inode);
1021         ref_count += ref_change;
1022         ext4_xattr_inode_set_ref(ea_inode, ref_count);
1023
1024         if (ref_change > 0) {
1025                 WARN_ONCE(ref_count <= 0, "EA inode %lu ref_count=%lld",
1026                           ea_inode->i_ino, ref_count);
1027
1028                 if (ref_count == 1) {
1029                         WARN_ONCE(ea_inode->i_nlink, "EA inode %lu i_nlink=%u",
1030                                   ea_inode->i_ino, ea_inode->i_nlink);
1031
1032                         set_nlink(ea_inode, 1);
1033                         ext4_orphan_del(handle, ea_inode);
1034                 }
1035         } else {
1036                 WARN_ONCE(ref_count < 0, "EA inode %lu ref_count=%lld",
1037                           ea_inode->i_ino, ref_count);
1038
1039                 if (ref_count == 0) {
1040                         WARN_ONCE(ea_inode->i_nlink != 1,
1041                                   "EA inode %lu i_nlink=%u",
1042                                   ea_inode->i_ino, ea_inode->i_nlink);
1043
1044                         clear_nlink(ea_inode);
1045                         ext4_orphan_add(handle, ea_inode);
1046                 }
1047         }
1048
1049         ret = ext4_mark_iloc_dirty(handle, ea_inode, &iloc);
1050         if (ret)
1051                 ext4_warning_inode(ea_inode,
1052                                    "ext4_mark_iloc_dirty() failed ret=%d", ret);
1053 out:
1054         inode_unlock(ea_inode);
1055         return ret;
1056 }
1057
1058 static int ext4_xattr_inode_inc_ref(handle_t *handle, struct inode *ea_inode)
1059 {
1060         return ext4_xattr_inode_update_ref(handle, ea_inode, 1);
1061 }
1062
1063 static int ext4_xattr_inode_dec_ref(handle_t *handle, struct inode *ea_inode)
1064 {
1065         return ext4_xattr_inode_update_ref(handle, ea_inode, -1);
1066 }
1067
1068 static int ext4_xattr_inode_inc_ref_all(handle_t *handle, struct inode *parent,
1069                                         struct ext4_xattr_entry *first)
1070 {
1071         struct inode *ea_inode;
1072         struct ext4_xattr_entry *entry;
1073         struct ext4_xattr_entry *failed_entry;
1074         unsigned int ea_ino;
1075         int err, saved_err;
1076
1077         for (entry = first; !IS_LAST_ENTRY(entry);
1078              entry = EXT4_XATTR_NEXT(entry)) {
1079                 if (!entry->e_value_inum)
1080                         continue;
1081                 ea_ino = le32_to_cpu(entry->e_value_inum);
1082                 err = ext4_xattr_inode_iget(parent, ea_ino,
1083                                             le32_to_cpu(entry->e_hash),
1084                                             &ea_inode);
1085                 if (err)
1086                         goto cleanup;
1087                 err = ext4_xattr_inode_inc_ref(handle, ea_inode);
1088                 if (err) {
1089                         ext4_warning_inode(ea_inode, "inc ref error %d", err);
1090                         iput(ea_inode);
1091                         goto cleanup;
1092                 }
1093                 iput(ea_inode);
1094         }
1095         return 0;
1096
1097 cleanup:
1098         saved_err = err;
1099         failed_entry = entry;
1100
1101         for (entry = first; entry != failed_entry;
1102              entry = EXT4_XATTR_NEXT(entry)) {
1103                 if (!entry->e_value_inum)
1104                         continue;
1105                 ea_ino = le32_to_cpu(entry->e_value_inum);
1106                 err = ext4_xattr_inode_iget(parent, ea_ino,
1107                                             le32_to_cpu(entry->e_hash),
1108                                             &ea_inode);
1109                 if (err) {
1110                         ext4_warning(parent->i_sb,
1111                                      "cleanup ea_ino %u iget error %d", ea_ino,
1112                                      err);
1113                         continue;
1114                 }
1115                 err = ext4_xattr_inode_dec_ref(handle, ea_inode);
1116                 if (err)
1117                         ext4_warning_inode(ea_inode, "cleanup dec ref error %d",
1118                                            err);
1119                 iput(ea_inode);
1120         }
1121         return saved_err;
1122 }
1123
1124 static int ext4_xattr_restart_fn(handle_t *handle, struct inode *inode,
1125                         struct buffer_head *bh, bool block_csum, bool dirty)
1126 {
1127         int error;
1128
1129         if (bh && dirty) {
1130                 if (block_csum)
1131                         ext4_xattr_block_csum_set(inode, bh);
1132                 error = ext4_handle_dirty_metadata(handle, NULL, bh);
1133                 if (error) {
1134                         ext4_warning(inode->i_sb, "Handle metadata (error %d)",
1135                                      error);
1136                         return error;
1137                 }
1138         }
1139         return 0;
1140 }
1141
1142 static void
1143 ext4_xattr_inode_dec_ref_all(handle_t *handle, struct inode *parent,
1144                              struct buffer_head *bh,
1145                              struct ext4_xattr_entry *first, bool block_csum,
1146                              struct ext4_xattr_inode_array **ea_inode_array,
1147                              int extra_credits, bool skip_quota)
1148 {
1149         struct inode *ea_inode;
1150         struct ext4_xattr_entry *entry;
1151         bool dirty = false;
1152         unsigned int ea_ino;
1153         int err;
1154         int credits;
1155
1156         /* One credit for dec ref on ea_inode, one for orphan list addition, */
1157         credits = 2 + extra_credits;
1158
1159         for (entry = first; !IS_LAST_ENTRY(entry);
1160              entry = EXT4_XATTR_NEXT(entry)) {
1161                 if (!entry->e_value_inum)
1162                         continue;
1163                 ea_ino = le32_to_cpu(entry->e_value_inum);
1164                 err = ext4_xattr_inode_iget(parent, ea_ino,
1165                                             le32_to_cpu(entry->e_hash),
1166                                             &ea_inode);
1167                 if (err)
1168                         continue;
1169
1170                 err = ext4_expand_inode_array(ea_inode_array, ea_inode);
1171                 if (err) {
1172                         ext4_warning_inode(ea_inode,
1173                                            "Expand inode array err=%d", err);
1174                         iput(ea_inode);
1175                         continue;
1176                 }
1177
1178                 err = ext4_journal_ensure_credits_fn(handle, credits, credits,
1179                         ext4_free_metadata_revoke_credits(parent->i_sb, 1),
1180                         ext4_xattr_restart_fn(handle, parent, bh, block_csum,
1181                                               dirty));
1182                 if (err < 0) {
1183                         ext4_warning_inode(ea_inode, "Ensure credits err=%d",
1184                                            err);
1185                         continue;
1186                 }
1187                 if (err > 0) {
1188                         err = ext4_journal_get_write_access(handle,
1189                                         parent->i_sb, bh, EXT4_JTR_NONE);
1190                         if (err) {
1191                                 ext4_warning_inode(ea_inode,
1192                                                 "Re-get write access err=%d",
1193                                                 err);
1194                                 continue;
1195                         }
1196                 }
1197
1198                 err = ext4_xattr_inode_dec_ref(handle, ea_inode);
1199                 if (err) {
1200                         ext4_warning_inode(ea_inode, "ea_inode dec ref err=%d",
1201                                            err);
1202                         continue;
1203                 }
1204
1205                 if (!skip_quota)
1206                         ext4_xattr_inode_free_quota(parent, ea_inode,
1207                                               le32_to_cpu(entry->e_value_size));
1208
1209                 /*
1210                  * Forget about ea_inode within the same transaction that
1211                  * decrements the ref count. This avoids duplicate decrements in
1212                  * case the rest of the work spills over to subsequent
1213                  * transactions.
1214                  */
1215                 entry->e_value_inum = 0;
1216                 entry->e_value_size = 0;
1217
1218                 dirty = true;
1219         }
1220
1221         if (dirty) {
1222                 /*
1223                  * Note that we are deliberately skipping csum calculation for
1224                  * the final update because we do not expect any journal
1225                  * restarts until xattr block is freed.
1226                  */
1227
1228                 err = ext4_handle_dirty_metadata(handle, NULL, bh);
1229                 if (err)
1230                         ext4_warning_inode(parent,
1231                                            "handle dirty metadata err=%d", err);
1232         }
1233 }
1234
1235 /*
1236  * Release the xattr block BH: If the reference count is > 1, decrement it;
1237  * otherwise free the block.
1238  */
1239 static void
1240 ext4_xattr_release_block(handle_t *handle, struct inode *inode,
1241                          struct buffer_head *bh,
1242                          struct ext4_xattr_inode_array **ea_inode_array,
1243                          int extra_credits)
1244 {
1245         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
1246         u32 hash, ref;
1247         int error = 0;
1248
1249         BUFFER_TRACE(bh, "get_write_access");
1250         error = ext4_journal_get_write_access(handle, inode->i_sb, bh,
1251                                               EXT4_JTR_NONE);
1252         if (error)
1253                 goto out;
1254
1255 retry_ref:
1256         lock_buffer(bh);
1257         hash = le32_to_cpu(BHDR(bh)->h_hash);
1258         ref = le32_to_cpu(BHDR(bh)->h_refcount);
1259         if (ref == 1) {
1260                 ea_bdebug(bh, "refcount now=0; freeing");
1261                 /*
1262                  * This must happen under buffer lock for
1263                  * ext4_xattr_block_set() to reliably detect freed block
1264                  */
1265                 if (ea_block_cache) {
1266                         struct mb_cache_entry *oe;
1267
1268                         oe = mb_cache_entry_delete_or_get(ea_block_cache, hash,
1269                                                           bh->b_blocknr);
1270                         if (oe) {
1271                                 unlock_buffer(bh);
1272                                 mb_cache_entry_wait_unused(oe);
1273                                 mb_cache_entry_put(ea_block_cache, oe);
1274                                 goto retry_ref;
1275                         }
1276                 }
1277                 get_bh(bh);
1278                 unlock_buffer(bh);
1279
1280                 if (ext4_has_feature_ea_inode(inode->i_sb))
1281                         ext4_xattr_inode_dec_ref_all(handle, inode, bh,
1282                                                      BFIRST(bh),
1283                                                      true /* block_csum */,
1284                                                      ea_inode_array,
1285                                                      extra_credits,
1286                                                      true /* skip_quota */);
1287                 ext4_free_blocks(handle, inode, bh, 0, 1,
1288                                  EXT4_FREE_BLOCKS_METADATA |
1289                                  EXT4_FREE_BLOCKS_FORGET);
1290         } else {
1291                 ref--;
1292                 BHDR(bh)->h_refcount = cpu_to_le32(ref);
1293                 if (ref == EXT4_XATTR_REFCOUNT_MAX - 1) {
1294                         struct mb_cache_entry *ce;
1295
1296                         if (ea_block_cache) {
1297                                 ce = mb_cache_entry_get(ea_block_cache, hash,
1298                                                         bh->b_blocknr);
1299                                 if (ce) {
1300                                         set_bit(MBE_REUSABLE_B, &ce->e_flags);
1301                                         mb_cache_entry_put(ea_block_cache, ce);
1302                                 }
1303                         }
1304                 }
1305
1306                 ext4_xattr_block_csum_set(inode, bh);
1307                 /*
1308                  * Beware of this ugliness: Releasing of xattr block references
1309                  * from different inodes can race and so we have to protect
1310                  * from a race where someone else frees the block (and releases
1311                  * its journal_head) before we are done dirtying the buffer. In
1312                  * nojournal mode this race is harmless and we actually cannot
1313                  * call ext4_handle_dirty_metadata() with locked buffer as
1314                  * that function can call sync_dirty_buffer() so for that case
1315                  * we handle the dirtying after unlocking the buffer.
1316                  */
1317                 if (ext4_handle_valid(handle))
1318                         error = ext4_handle_dirty_metadata(handle, inode, bh);
1319                 unlock_buffer(bh);
1320                 if (!ext4_handle_valid(handle))
1321                         error = ext4_handle_dirty_metadata(handle, inode, bh);
1322                 if (IS_SYNC(inode))
1323                         ext4_handle_sync(handle);
1324                 dquot_free_block(inode, EXT4_C2B(EXT4_SB(inode->i_sb), 1));
1325                 ea_bdebug(bh, "refcount now=%d; releasing",
1326                           le32_to_cpu(BHDR(bh)->h_refcount));
1327         }
1328 out:
1329         ext4_std_error(inode->i_sb, error);
1330         return;
1331 }
1332
1333 /*
1334  * Find the available free space for EAs. This also returns the total number of
1335  * bytes used by EA entries.
1336  */
1337 static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
1338                                     size_t *min_offs, void *base, int *total)
1339 {
1340         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
1341                 if (!last->e_value_inum && last->e_value_size) {
1342                         size_t offs = le16_to_cpu(last->e_value_offs);
1343                         if (offs < *min_offs)
1344                                 *min_offs = offs;
1345                 }
1346                 if (total)
1347                         *total += EXT4_XATTR_LEN(last->e_name_len);
1348         }
1349         return (*min_offs - ((void *)last - base) - sizeof(__u32));
1350 }
1351
1352 /*
1353  * Write the value of the EA in an inode.
1354  */
1355 static int ext4_xattr_inode_write(handle_t *handle, struct inode *ea_inode,
1356                                   const void *buf, int bufsize)
1357 {
1358         struct buffer_head *bh = NULL;
1359         unsigned long block = 0;
1360         int blocksize = ea_inode->i_sb->s_blocksize;
1361         int max_blocks = (bufsize + blocksize - 1) >> ea_inode->i_blkbits;
1362         int csize, wsize = 0;
1363         int ret = 0, ret2 = 0;
1364         int retries = 0;
1365
1366 retry:
1367         while (ret >= 0 && ret < max_blocks) {
1368                 struct ext4_map_blocks map;
1369                 map.m_lblk = block += ret;
1370                 map.m_len = max_blocks -= ret;
1371
1372                 ret = ext4_map_blocks(handle, ea_inode, &map,
1373                                       EXT4_GET_BLOCKS_CREATE);
1374                 if (ret <= 0) {
1375                         ext4_mark_inode_dirty(handle, ea_inode);
1376                         if (ret == -ENOSPC &&
1377                             ext4_should_retry_alloc(ea_inode->i_sb, &retries)) {
1378                                 ret = 0;
1379                                 goto retry;
1380                         }
1381                         break;
1382                 }
1383         }
1384
1385         if (ret < 0)
1386                 return ret;
1387
1388         block = 0;
1389         while (wsize < bufsize) {
1390                 brelse(bh);
1391                 csize = (bufsize - wsize) > blocksize ? blocksize :
1392                                                                 bufsize - wsize;
1393                 bh = ext4_getblk(handle, ea_inode, block, 0);
1394                 if (IS_ERR(bh))
1395                         return PTR_ERR(bh);
1396                 if (!bh) {
1397                         WARN_ON_ONCE(1);
1398                         EXT4_ERROR_INODE(ea_inode,
1399                                          "ext4_getblk() return bh = NULL");
1400                         return -EFSCORRUPTED;
1401                 }
1402                 ret = ext4_journal_get_write_access(handle, ea_inode->i_sb, bh,
1403                                                    EXT4_JTR_NONE);
1404                 if (ret)
1405                         goto out;
1406
1407                 memcpy(bh->b_data, buf, csize);
1408                 set_buffer_uptodate(bh);
1409                 ext4_handle_dirty_metadata(handle, ea_inode, bh);
1410
1411                 buf += csize;
1412                 wsize += csize;
1413                 block += 1;
1414         }
1415
1416         inode_lock(ea_inode);
1417         i_size_write(ea_inode, wsize);
1418         ext4_update_i_disksize(ea_inode, wsize);
1419         inode_unlock(ea_inode);
1420
1421         ret2 = ext4_mark_inode_dirty(handle, ea_inode);
1422         if (unlikely(ret2 && !ret))
1423                 ret = ret2;
1424
1425 out:
1426         brelse(bh);
1427
1428         return ret;
1429 }
1430
1431 /*
1432  * Create an inode to store the value of a large EA.
1433  */
1434 static struct inode *ext4_xattr_inode_create(handle_t *handle,
1435                                              struct inode *inode, u32 hash)
1436 {
1437         struct inode *ea_inode = NULL;
1438         uid_t owner[2] = { i_uid_read(inode), i_gid_read(inode) };
1439         int err;
1440
1441         /*
1442          * Let the next inode be the goal, so we try and allocate the EA inode
1443          * in the same group, or nearby one.
1444          */
1445         ea_inode = ext4_new_inode(handle, inode->i_sb->s_root->d_inode,
1446                                   S_IFREG | 0600, NULL, inode->i_ino + 1, owner,
1447                                   EXT4_EA_INODE_FL);
1448         if (!IS_ERR(ea_inode)) {
1449                 ea_inode->i_op = &ext4_file_inode_operations;
1450                 ea_inode->i_fop = &ext4_file_operations;
1451                 ext4_set_aops(ea_inode);
1452                 ext4_xattr_inode_set_class(ea_inode);
1453                 unlock_new_inode(ea_inode);
1454                 ext4_xattr_inode_set_ref(ea_inode, 1);
1455                 ext4_xattr_inode_set_hash(ea_inode, hash);
1456                 err = ext4_mark_inode_dirty(handle, ea_inode);
1457                 if (!err)
1458                         err = ext4_inode_attach_jinode(ea_inode);
1459                 if (err) {
1460                         if (ext4_xattr_inode_dec_ref(handle, ea_inode))
1461                                 ext4_warning_inode(ea_inode,
1462                                         "cleanup dec ref error %d", err);
1463                         iput(ea_inode);
1464                         return ERR_PTR(err);
1465                 }
1466
1467                 /*
1468                  * Xattr inodes are shared therefore quota charging is performed
1469                  * at a higher level.
1470                  */
1471                 dquot_free_inode(ea_inode);
1472                 dquot_drop(ea_inode);
1473                 inode_lock(ea_inode);
1474                 ea_inode->i_flags |= S_NOQUOTA;
1475                 inode_unlock(ea_inode);
1476         }
1477
1478         return ea_inode;
1479 }
1480
1481 static struct inode *
1482 ext4_xattr_inode_cache_find(struct inode *inode, const void *value,
1483                             size_t value_len, u32 hash)
1484 {
1485         struct inode *ea_inode;
1486         struct mb_cache_entry *ce;
1487         struct mb_cache *ea_inode_cache = EA_INODE_CACHE(inode);
1488         void *ea_data;
1489
1490         if (!ea_inode_cache)
1491                 return NULL;
1492
1493         ce = mb_cache_entry_find_first(ea_inode_cache, hash);
1494         if (!ce)
1495                 return NULL;
1496
1497         WARN_ON_ONCE(ext4_handle_valid(journal_current_handle()) &&
1498                      !(current->flags & PF_MEMALLOC_NOFS));
1499
1500         ea_data = kvmalloc(value_len, GFP_KERNEL);
1501         if (!ea_data) {
1502                 mb_cache_entry_put(ea_inode_cache, ce);
1503                 return NULL;
1504         }
1505
1506         while (ce) {
1507                 ea_inode = ext4_iget(inode->i_sb, ce->e_value,
1508                                      EXT4_IGET_NORMAL);
1509                 if (!IS_ERR(ea_inode) &&
1510                     !is_bad_inode(ea_inode) &&
1511                     (EXT4_I(ea_inode)->i_flags & EXT4_EA_INODE_FL) &&
1512                     i_size_read(ea_inode) == value_len &&
1513                     !ext4_xattr_inode_read(ea_inode, ea_data, value_len) &&
1514                     !ext4_xattr_inode_verify_hashes(ea_inode, NULL, ea_data,
1515                                                     value_len) &&
1516                     !memcmp(value, ea_data, value_len)) {
1517                         mb_cache_entry_touch(ea_inode_cache, ce);
1518                         mb_cache_entry_put(ea_inode_cache, ce);
1519                         kvfree(ea_data);
1520                         return ea_inode;
1521                 }
1522
1523                 if (!IS_ERR(ea_inode))
1524                         iput(ea_inode);
1525                 ce = mb_cache_entry_find_next(ea_inode_cache, ce);
1526         }
1527         kvfree(ea_data);
1528         return NULL;
1529 }
1530
1531 /*
1532  * Add value of the EA in an inode.
1533  */
1534 static int ext4_xattr_inode_lookup_create(handle_t *handle, struct inode *inode,
1535                                           const void *value, size_t value_len,
1536                                           struct inode **ret_inode)
1537 {
1538         struct inode *ea_inode;
1539         u32 hash;
1540         int err;
1541
1542         hash = ext4_xattr_inode_hash(EXT4_SB(inode->i_sb), value, value_len);
1543         ea_inode = ext4_xattr_inode_cache_find(inode, value, value_len, hash);
1544         if (ea_inode) {
1545                 err = ext4_xattr_inode_inc_ref(handle, ea_inode);
1546                 if (err) {
1547                         iput(ea_inode);
1548                         return err;
1549                 }
1550
1551                 *ret_inode = ea_inode;
1552                 return 0;
1553         }
1554
1555         /* Create an inode for the EA value */
1556         ea_inode = ext4_xattr_inode_create(handle, inode, hash);
1557         if (IS_ERR(ea_inode))
1558                 return PTR_ERR(ea_inode);
1559
1560         err = ext4_xattr_inode_write(handle, ea_inode, value, value_len);
1561         if (err) {
1562                 if (ext4_xattr_inode_dec_ref(handle, ea_inode))
1563                         ext4_warning_inode(ea_inode, "cleanup dec ref error %d", err);
1564                 iput(ea_inode);
1565                 return err;
1566         }
1567
1568         if (EA_INODE_CACHE(inode))
1569                 mb_cache_entry_create(EA_INODE_CACHE(inode), GFP_NOFS, hash,
1570                                       ea_inode->i_ino, true /* reusable */);
1571
1572         *ret_inode = ea_inode;
1573         return 0;
1574 }
1575
1576 /*
1577  * Reserve min(block_size/8, 1024) bytes for xattr entries/names if ea_inode
1578  * feature is enabled.
1579  */
1580 #define EXT4_XATTR_BLOCK_RESERVE(inode) min(i_blocksize(inode)/8, 1024U)
1581
1582 static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
1583                                 struct ext4_xattr_search *s,
1584                                 handle_t *handle, struct inode *inode,
1585                                 bool is_block)
1586 {
1587         struct ext4_xattr_entry *last, *next;
1588         struct ext4_xattr_entry *here = s->here;
1589         size_t min_offs = s->end - s->base, name_len = strlen(i->name);
1590         int in_inode = i->in_inode;
1591         struct inode *old_ea_inode = NULL;
1592         struct inode *new_ea_inode = NULL;
1593         size_t old_size, new_size;
1594         int ret;
1595
1596         /* Space used by old and new values. */
1597         old_size = (!s->not_found && !here->e_value_inum) ?
1598                         EXT4_XATTR_SIZE(le32_to_cpu(here->e_value_size)) : 0;
1599         new_size = (i->value && !in_inode) ? EXT4_XATTR_SIZE(i->value_len) : 0;
1600
1601         /*
1602          * Optimization for the simple case when old and new values have the
1603          * same padded sizes. Not applicable if external inodes are involved.
1604          */
1605         if (new_size && new_size == old_size) {
1606                 size_t offs = le16_to_cpu(here->e_value_offs);
1607                 void *val = s->base + offs;
1608
1609                 here->e_value_size = cpu_to_le32(i->value_len);
1610                 if (i->value == EXT4_ZERO_XATTR_VALUE) {
1611                         memset(val, 0, new_size);
1612                 } else {
1613                         memcpy(val, i->value, i->value_len);
1614                         /* Clear padding bytes. */
1615                         memset(val + i->value_len, 0, new_size - i->value_len);
1616                 }
1617                 goto update_hash;
1618         }
1619
1620         /* Compute min_offs and last. */
1621         last = s->first;
1622         for (; !IS_LAST_ENTRY(last); last = next) {
1623                 next = EXT4_XATTR_NEXT(last);
1624                 if ((void *)next >= s->end) {
1625                         EXT4_ERROR_INODE(inode, "corrupted xattr entries");
1626                         ret = -EFSCORRUPTED;
1627                         goto out;
1628                 }
1629                 if (!last->e_value_inum && last->e_value_size) {
1630                         size_t offs = le16_to_cpu(last->e_value_offs);
1631                         if (offs < min_offs)
1632                                 min_offs = offs;
1633                 }
1634         }
1635
1636         /* Check whether we have enough space. */
1637         if (i->value) {
1638                 size_t free;
1639
1640                 free = min_offs - ((void *)last - s->base) - sizeof(__u32);
1641                 if (!s->not_found)
1642                         free += EXT4_XATTR_LEN(name_len) + old_size;
1643
1644                 if (free < EXT4_XATTR_LEN(name_len) + new_size) {
1645                         ret = -ENOSPC;
1646                         goto out;
1647                 }
1648
1649                 /*
1650                  * If storing the value in an external inode is an option,
1651                  * reserve space for xattr entries/names in the external
1652                  * attribute block so that a long value does not occupy the
1653                  * whole space and prevent further entries being added.
1654                  */
1655                 if (ext4_has_feature_ea_inode(inode->i_sb) &&
1656                     new_size && is_block &&
1657                     (min_offs + old_size - new_size) <
1658                                         EXT4_XATTR_BLOCK_RESERVE(inode)) {
1659                         ret = -ENOSPC;
1660                         goto out;
1661                 }
1662         }
1663
1664         /*
1665          * Getting access to old and new ea inodes is subject to failures.
1666          * Finish that work before doing any modifications to the xattr data.
1667          */
1668         if (!s->not_found && here->e_value_inum) {
1669                 ret = ext4_xattr_inode_iget(inode,
1670                                             le32_to_cpu(here->e_value_inum),
1671                                             le32_to_cpu(here->e_hash),
1672                                             &old_ea_inode);
1673                 if (ret) {
1674                         old_ea_inode = NULL;
1675                         goto out;
1676                 }
1677         }
1678         if (i->value && in_inode) {
1679                 WARN_ON_ONCE(!i->value_len);
1680
1681                 ret = ext4_xattr_inode_alloc_quota(inode, i->value_len);
1682                 if (ret)
1683                         goto out;
1684
1685                 ret = ext4_xattr_inode_lookup_create(handle, inode, i->value,
1686                                                      i->value_len,
1687                                                      &new_ea_inode);
1688                 if (ret) {
1689                         new_ea_inode = NULL;
1690                         ext4_xattr_inode_free_quota(inode, NULL, i->value_len);
1691                         goto out;
1692                 }
1693         }
1694
1695         if (old_ea_inode) {
1696                 /* We are ready to release ref count on the old_ea_inode. */
1697                 ret = ext4_xattr_inode_dec_ref(handle, old_ea_inode);
1698                 if (ret) {
1699                         /* Release newly required ref count on new_ea_inode. */
1700                         if (new_ea_inode) {
1701                                 int err;
1702
1703                                 err = ext4_xattr_inode_dec_ref(handle,
1704                                                                new_ea_inode);
1705                                 if (err)
1706                                         ext4_warning_inode(new_ea_inode,
1707                                                   "dec ref new_ea_inode err=%d",
1708                                                   err);
1709                                 ext4_xattr_inode_free_quota(inode, new_ea_inode,
1710                                                             i->value_len);
1711                         }
1712                         goto out;
1713                 }
1714
1715                 ext4_xattr_inode_free_quota(inode, old_ea_inode,
1716                                             le32_to_cpu(here->e_value_size));
1717         }
1718
1719         /* No failures allowed past this point. */
1720
1721         if (!s->not_found && here->e_value_size && !here->e_value_inum) {
1722                 /* Remove the old value. */
1723                 void *first_val = s->base + min_offs;
1724                 size_t offs = le16_to_cpu(here->e_value_offs);
1725                 void *val = s->base + offs;
1726
1727                 memmove(first_val + old_size, first_val, val - first_val);
1728                 memset(first_val, 0, old_size);
1729                 min_offs += old_size;
1730
1731                 /* Adjust all value offsets. */
1732                 last = s->first;
1733                 while (!IS_LAST_ENTRY(last)) {
1734                         size_t o = le16_to_cpu(last->e_value_offs);
1735
1736                         if (!last->e_value_inum &&
1737                             last->e_value_size && o < offs)
1738                                 last->e_value_offs = cpu_to_le16(o + old_size);
1739                         last = EXT4_XATTR_NEXT(last);
1740                 }
1741         }
1742
1743         if (!i->value) {
1744                 /* Remove old name. */
1745                 size_t size = EXT4_XATTR_LEN(name_len);
1746
1747                 last = ENTRY((void *)last - size);
1748                 memmove(here, (void *)here + size,
1749                         (void *)last - (void *)here + sizeof(__u32));
1750                 memset(last, 0, size);
1751         } else if (s->not_found) {
1752                 /* Insert new name. */
1753                 size_t size = EXT4_XATTR_LEN(name_len);
1754                 size_t rest = (void *)last - (void *)here + sizeof(__u32);
1755
1756                 memmove((void *)here + size, here, rest);
1757                 memset(here, 0, size);
1758                 here->e_name_index = i->name_index;
1759                 here->e_name_len = name_len;
1760                 memcpy(here->e_name, i->name, name_len);
1761         } else {
1762                 /* This is an update, reset value info. */
1763                 here->e_value_inum = 0;
1764                 here->e_value_offs = 0;
1765                 here->e_value_size = 0;
1766         }
1767
1768         if (i->value) {
1769                 /* Insert new value. */
1770                 if (in_inode) {
1771                         here->e_value_inum = cpu_to_le32(new_ea_inode->i_ino);
1772                 } else if (i->value_len) {
1773                         void *val = s->base + min_offs - new_size;
1774
1775                         here->e_value_offs = cpu_to_le16(min_offs - new_size);
1776                         if (i->value == EXT4_ZERO_XATTR_VALUE) {
1777                                 memset(val, 0, new_size);
1778                         } else {
1779                                 memcpy(val, i->value, i->value_len);
1780                                 /* Clear padding bytes. */
1781                                 memset(val + i->value_len, 0,
1782                                        new_size - i->value_len);
1783                         }
1784                 }
1785                 here->e_value_size = cpu_to_le32(i->value_len);
1786         }
1787
1788 update_hash:
1789         if (i->value) {
1790                 __le32 hash = 0;
1791
1792                 /* Entry hash calculation. */
1793                 if (in_inode) {
1794                         __le32 crc32c_hash;
1795
1796                         /*
1797                          * Feed crc32c hash instead of the raw value for entry
1798                          * hash calculation. This is to avoid walking
1799                          * potentially long value buffer again.
1800                          */
1801                         crc32c_hash = cpu_to_le32(
1802                                        ext4_xattr_inode_get_hash(new_ea_inode));
1803                         hash = ext4_xattr_hash_entry(here->e_name,
1804                                                      here->e_name_len,
1805                                                      &crc32c_hash, 1);
1806                 } else if (is_block) {
1807                         __le32 *value = s->base + le16_to_cpu(
1808                                                         here->e_value_offs);
1809
1810                         hash = ext4_xattr_hash_entry(here->e_name,
1811                                                      here->e_name_len, value,
1812                                                      new_size >> 2);
1813                 }
1814                 here->e_hash = hash;
1815         }
1816
1817         if (is_block)
1818                 ext4_xattr_rehash((struct ext4_xattr_header *)s->base);
1819
1820         ret = 0;
1821 out:
1822         iput(old_ea_inode);
1823         iput(new_ea_inode);
1824         return ret;
1825 }
1826
1827 struct ext4_xattr_block_find {
1828         struct ext4_xattr_search s;
1829         struct buffer_head *bh;
1830 };
1831
1832 static int
1833 ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
1834                       struct ext4_xattr_block_find *bs)
1835 {
1836         struct super_block *sb = inode->i_sb;
1837         int error;
1838
1839         ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
1840                   i->name_index, i->name, i->value, (long)i->value_len);
1841
1842         if (EXT4_I(inode)->i_file_acl) {
1843                 /* The inode already has an extended attribute block. */
1844                 bs->bh = ext4_sb_bread(sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
1845                 if (IS_ERR(bs->bh)) {
1846                         error = PTR_ERR(bs->bh);
1847                         bs->bh = NULL;
1848                         return error;
1849                 }
1850                 ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
1851                         atomic_read(&(bs->bh->b_count)),
1852                         le32_to_cpu(BHDR(bs->bh)->h_refcount));
1853                 error = ext4_xattr_check_block(inode, bs->bh);
1854                 if (error)
1855                         return error;
1856                 /* Find the named attribute. */
1857                 bs->s.base = BHDR(bs->bh);
1858                 bs->s.first = BFIRST(bs->bh);
1859                 bs->s.end = bs->bh->b_data + bs->bh->b_size;
1860                 bs->s.here = bs->s.first;
1861                 error = xattr_find_entry(inode, &bs->s.here, bs->s.end,
1862                                          i->name_index, i->name, 1);
1863                 if (error && error != -ENODATA)
1864                         return error;
1865                 bs->s.not_found = error;
1866         }
1867         return 0;
1868 }
1869
1870 static int
1871 ext4_xattr_block_set(handle_t *handle, struct inode *inode,
1872                      struct ext4_xattr_info *i,
1873                      struct ext4_xattr_block_find *bs)
1874 {
1875         struct super_block *sb = inode->i_sb;
1876         struct buffer_head *new_bh = NULL;
1877         struct ext4_xattr_search s_copy = bs->s;
1878         struct ext4_xattr_search *s = &s_copy;
1879         struct mb_cache_entry *ce = NULL;
1880         int error = 0;
1881         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
1882         struct inode *ea_inode = NULL, *tmp_inode;
1883         size_t old_ea_inode_quota = 0;
1884         unsigned int ea_ino;
1885
1886
1887 #define header(x) ((struct ext4_xattr_header *)(x))
1888
1889         if (s->base) {
1890                 int offset = (char *)s->here - bs->bh->b_data;
1891
1892                 BUFFER_TRACE(bs->bh, "get_write_access");
1893                 error = ext4_journal_get_write_access(handle, sb, bs->bh,
1894                                                       EXT4_JTR_NONE);
1895                 if (error)
1896                         goto cleanup;
1897                 lock_buffer(bs->bh);
1898
1899                 if (header(s->base)->h_refcount == cpu_to_le32(1)) {
1900                         __u32 hash = le32_to_cpu(BHDR(bs->bh)->h_hash);
1901
1902                         /*
1903                          * This must happen under buffer lock for
1904                          * ext4_xattr_block_set() to reliably detect modified
1905                          * block
1906                          */
1907                         if (ea_block_cache) {
1908                                 struct mb_cache_entry *oe;
1909
1910                                 oe = mb_cache_entry_delete_or_get(ea_block_cache,
1911                                         hash, bs->bh->b_blocknr);
1912                                 if (oe) {
1913                                         /*
1914                                          * Xattr block is getting reused. Leave
1915                                          * it alone.
1916                                          */
1917                                         mb_cache_entry_put(ea_block_cache, oe);
1918                                         goto clone_block;
1919                                 }
1920                         }
1921                         ea_bdebug(bs->bh, "modifying in-place");
1922                         error = ext4_xattr_set_entry(i, s, handle, inode,
1923                                                      true /* is_block */);
1924                         ext4_xattr_block_csum_set(inode, bs->bh);
1925                         unlock_buffer(bs->bh);
1926                         if (error == -EFSCORRUPTED)
1927                                 goto bad_block;
1928                         if (!error)
1929                                 error = ext4_handle_dirty_metadata(handle,
1930                                                                    inode,
1931                                                                    bs->bh);
1932                         if (error)
1933                                 goto cleanup;
1934                         goto inserted;
1935                 }
1936 clone_block:
1937                 unlock_buffer(bs->bh);
1938                 ea_bdebug(bs->bh, "cloning");
1939                 s->base = kmemdup(BHDR(bs->bh), bs->bh->b_size, GFP_NOFS);
1940                 error = -ENOMEM;
1941                 if (s->base == NULL)
1942                         goto cleanup;
1943                 s->first = ENTRY(header(s->base)+1);
1944                 header(s->base)->h_refcount = cpu_to_le32(1);
1945                 s->here = ENTRY(s->base + offset);
1946                 s->end = s->base + bs->bh->b_size;
1947
1948                 /*
1949                  * If existing entry points to an xattr inode, we need
1950                  * to prevent ext4_xattr_set_entry() from decrementing
1951                  * ref count on it because the reference belongs to the
1952                  * original block. In this case, make the entry look
1953                  * like it has an empty value.
1954                  */
1955                 if (!s->not_found && s->here->e_value_inum) {
1956                         ea_ino = le32_to_cpu(s->here->e_value_inum);
1957                         error = ext4_xattr_inode_iget(inode, ea_ino,
1958                                       le32_to_cpu(s->here->e_hash),
1959                                       &tmp_inode);
1960                         if (error)
1961                                 goto cleanup;
1962
1963                         if (!ext4_test_inode_state(tmp_inode,
1964                                         EXT4_STATE_LUSTRE_EA_INODE)) {
1965                                 /*
1966                                  * Defer quota free call for previous
1967                                  * inode until success is guaranteed.
1968                                  */
1969                                 old_ea_inode_quota = le32_to_cpu(
1970                                                 s->here->e_value_size);
1971                         }
1972                         iput(tmp_inode);
1973
1974                         s->here->e_value_inum = 0;
1975                         s->here->e_value_size = 0;
1976                 }
1977         } else {
1978                 /* Allocate a buffer where we construct the new block. */
1979                 s->base = kzalloc(sb->s_blocksize, GFP_NOFS);
1980                 error = -ENOMEM;
1981                 if (s->base == NULL)
1982                         goto cleanup;
1983                 header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
1984                 header(s->base)->h_blocks = cpu_to_le32(1);
1985                 header(s->base)->h_refcount = cpu_to_le32(1);
1986                 s->first = ENTRY(header(s->base)+1);
1987                 s->here = ENTRY(header(s->base)+1);
1988                 s->end = s->base + sb->s_blocksize;
1989         }
1990
1991         error = ext4_xattr_set_entry(i, s, handle, inode, true /* is_block */);
1992         if (error == -EFSCORRUPTED)
1993                 goto bad_block;
1994         if (error)
1995                 goto cleanup;
1996
1997         if (i->value && s->here->e_value_inum) {
1998                 /*
1999                  * A ref count on ea_inode has been taken as part of the call to
2000                  * ext4_xattr_set_entry() above. We would like to drop this
2001                  * extra ref but we have to wait until the xattr block is
2002                  * initialized and has its own ref count on the ea_inode.
2003                  */
2004                 ea_ino = le32_to_cpu(s->here->e_value_inum);
2005                 error = ext4_xattr_inode_iget(inode, ea_ino,
2006                                               le32_to_cpu(s->here->e_hash),
2007                                               &ea_inode);
2008                 if (error) {
2009                         ea_inode = NULL;
2010                         goto cleanup;
2011                 }
2012         }
2013
2014 inserted:
2015         if (!IS_LAST_ENTRY(s->first)) {
2016                 new_bh = ext4_xattr_block_cache_find(inode, header(s->base),
2017                                                      &ce);
2018                 if (new_bh) {
2019                         /* We found an identical block in the cache. */
2020                         if (new_bh == bs->bh)
2021                                 ea_bdebug(new_bh, "keeping");
2022                         else {
2023                                 u32 ref;
2024
2025                                 WARN_ON_ONCE(dquot_initialize_needed(inode));
2026
2027                                 /* The old block is released after updating
2028                                    the inode. */
2029                                 error = dquot_alloc_block(inode,
2030                                                 EXT4_C2B(EXT4_SB(sb), 1));
2031                                 if (error)
2032                                         goto cleanup;
2033                                 BUFFER_TRACE(new_bh, "get_write_access");
2034                                 error = ext4_journal_get_write_access(
2035                                                 handle, sb, new_bh,
2036                                                 EXT4_JTR_NONE);
2037                                 if (error)
2038                                         goto cleanup_dquot;
2039                                 lock_buffer(new_bh);
2040                                 /*
2041                                  * We have to be careful about races with
2042                                  * adding references to xattr block. Once we
2043                                  * hold buffer lock xattr block's state is
2044                                  * stable so we can check the additional
2045                                  * reference fits.
2046                                  */
2047                                 ref = le32_to_cpu(BHDR(new_bh)->h_refcount) + 1;
2048                                 if (ref > EXT4_XATTR_REFCOUNT_MAX) {
2049                                         /*
2050                                          * Undo everything and check mbcache
2051                                          * again.
2052                                          */
2053                                         unlock_buffer(new_bh);
2054                                         dquot_free_block(inode,
2055                                                          EXT4_C2B(EXT4_SB(sb),
2056                                                                   1));
2057                                         brelse(new_bh);
2058                                         mb_cache_entry_put(ea_block_cache, ce);
2059                                         ce = NULL;
2060                                         new_bh = NULL;
2061                                         goto inserted;
2062                                 }
2063                                 BHDR(new_bh)->h_refcount = cpu_to_le32(ref);
2064                                 if (ref == EXT4_XATTR_REFCOUNT_MAX)
2065                                         clear_bit(MBE_REUSABLE_B, &ce->e_flags);
2066                                 ea_bdebug(new_bh, "reusing; refcount now=%d",
2067                                           ref);
2068                                 ext4_xattr_block_csum_set(inode, new_bh);
2069                                 unlock_buffer(new_bh);
2070                                 error = ext4_handle_dirty_metadata(handle,
2071                                                                    inode,
2072                                                                    new_bh);
2073                                 if (error)
2074                                         goto cleanup_dquot;
2075                         }
2076                         mb_cache_entry_touch(ea_block_cache, ce);
2077                         mb_cache_entry_put(ea_block_cache, ce);
2078                         ce = NULL;
2079                 } else if (bs->bh && s->base == bs->bh->b_data) {
2080                         /* We were modifying this block in-place. */
2081                         ea_bdebug(bs->bh, "keeping this block");
2082                         ext4_xattr_block_cache_insert(ea_block_cache, bs->bh);
2083                         new_bh = bs->bh;
2084                         get_bh(new_bh);
2085                 } else {
2086                         /* We need to allocate a new block */
2087                         ext4_fsblk_t goal, block;
2088
2089                         WARN_ON_ONCE(dquot_initialize_needed(inode));
2090
2091                         goal = ext4_group_first_block_no(sb,
2092                                                 EXT4_I(inode)->i_block_group);
2093                         block = ext4_new_meta_blocks(handle, inode, goal, 0,
2094                                                      NULL, &error);
2095                         if (error)
2096                                 goto cleanup;
2097
2098                         ea_idebug(inode, "creating block %llu",
2099                                   (unsigned long long)block);
2100
2101                         new_bh = sb_getblk(sb, block);
2102                         if (unlikely(!new_bh)) {
2103                                 error = -ENOMEM;
2104 getblk_failed:
2105                                 ext4_free_blocks(handle, inode, NULL, block, 1,
2106                                                  EXT4_FREE_BLOCKS_METADATA);
2107                                 goto cleanup;
2108                         }
2109                         error = ext4_xattr_inode_inc_ref_all(handle, inode,
2110                                                       ENTRY(header(s->base)+1));
2111                         if (error)
2112                                 goto getblk_failed;
2113                         if (ea_inode) {
2114                                 /* Drop the extra ref on ea_inode. */
2115                                 error = ext4_xattr_inode_dec_ref(handle,
2116                                                                  ea_inode);
2117                                 if (error)
2118                                         ext4_warning_inode(ea_inode,
2119                                                            "dec ref error=%d",
2120                                                            error);
2121                                 iput(ea_inode);
2122                                 ea_inode = NULL;
2123                         }
2124
2125                         lock_buffer(new_bh);
2126                         error = ext4_journal_get_create_access(handle, sb,
2127                                                         new_bh, EXT4_JTR_NONE);
2128                         if (error) {
2129                                 unlock_buffer(new_bh);
2130                                 error = -EIO;
2131                                 goto getblk_failed;
2132                         }
2133                         memcpy(new_bh->b_data, s->base, new_bh->b_size);
2134                         ext4_xattr_block_csum_set(inode, new_bh);
2135                         set_buffer_uptodate(new_bh);
2136                         unlock_buffer(new_bh);
2137                         ext4_xattr_block_cache_insert(ea_block_cache, new_bh);
2138                         error = ext4_handle_dirty_metadata(handle, inode,
2139                                                            new_bh);
2140                         if (error)
2141                                 goto cleanup;
2142                 }
2143         }
2144
2145         if (old_ea_inode_quota)
2146                 ext4_xattr_inode_free_quota(inode, NULL, old_ea_inode_quota);
2147
2148         /* Update the inode. */
2149         EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
2150
2151         /* Drop the previous xattr block. */
2152         if (bs->bh && bs->bh != new_bh) {
2153                 struct ext4_xattr_inode_array *ea_inode_array = NULL;
2154
2155                 ext4_xattr_release_block(handle, inode, bs->bh,
2156                                          &ea_inode_array,
2157                                          0 /* extra_credits */);
2158                 ext4_xattr_inode_array_free(ea_inode_array);
2159         }
2160         error = 0;
2161
2162 cleanup:
2163         if (ea_inode) {
2164                 int error2;
2165
2166                 error2 = ext4_xattr_inode_dec_ref(handle, ea_inode);
2167                 if (error2)
2168                         ext4_warning_inode(ea_inode, "dec ref error=%d",
2169                                            error2);
2170
2171                 /* If there was an error, revert the quota charge. */
2172                 if (error)
2173                         ext4_xattr_inode_free_quota(inode, ea_inode,
2174                                                     i_size_read(ea_inode));
2175                 iput(ea_inode);
2176         }
2177         if (ce)
2178                 mb_cache_entry_put(ea_block_cache, ce);
2179         brelse(new_bh);
2180         if (!(bs->bh && s->base == bs->bh->b_data))
2181                 kfree(s->base);
2182
2183         return error;
2184
2185 cleanup_dquot:
2186         dquot_free_block(inode, EXT4_C2B(EXT4_SB(sb), 1));
2187         goto cleanup;
2188
2189 bad_block:
2190         EXT4_ERROR_INODE(inode, "bad block %llu",
2191                          EXT4_I(inode)->i_file_acl);
2192         goto cleanup;
2193
2194 #undef header
2195 }
2196
2197 int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
2198                           struct ext4_xattr_ibody_find *is)
2199 {
2200         struct ext4_xattr_ibody_header *header;
2201         struct ext4_inode *raw_inode;
2202         int error;
2203
2204         if (!EXT4_INODE_HAS_XATTR_SPACE(inode))
2205                 return 0;
2206
2207         raw_inode = ext4_raw_inode(&is->iloc);
2208         header = IHDR(inode, raw_inode);
2209         is->s.base = is->s.first = IFIRST(header);
2210         is->s.here = is->s.first;
2211         is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
2212         if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
2213                 error = xattr_check_inode(inode, header, is->s.end);
2214                 if (error)
2215                         return error;
2216                 /* Find the named attribute. */
2217                 error = xattr_find_entry(inode, &is->s.here, is->s.end,
2218                                          i->name_index, i->name, 0);
2219                 if (error && error != -ENODATA)
2220                         return error;
2221                 is->s.not_found = error;
2222         }
2223         return 0;
2224 }
2225
2226 int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
2227                                 struct ext4_xattr_info *i,
2228                                 struct ext4_xattr_ibody_find *is)
2229 {
2230         struct ext4_xattr_ibody_header *header;
2231         struct ext4_xattr_search *s = &is->s;
2232         int error;
2233
2234         if (!EXT4_INODE_HAS_XATTR_SPACE(inode))
2235                 return -ENOSPC;
2236
2237         error = ext4_xattr_set_entry(i, s, handle, inode, false /* is_block */);
2238         if (error)
2239                 return error;
2240         header = IHDR(inode, ext4_raw_inode(&is->iloc));
2241         if (!IS_LAST_ENTRY(s->first)) {
2242                 header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
2243                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
2244         } else {
2245                 header->h_magic = cpu_to_le32(0);
2246                 ext4_clear_inode_state(inode, EXT4_STATE_XATTR);
2247         }
2248         return 0;
2249 }
2250
2251 static int ext4_xattr_value_same(struct ext4_xattr_search *s,
2252                                  struct ext4_xattr_info *i)
2253 {
2254         void *value;
2255
2256         /* When e_value_inum is set the value is stored externally. */
2257         if (s->here->e_value_inum)
2258                 return 0;
2259         if (le32_to_cpu(s->here->e_value_size) != i->value_len)
2260                 return 0;
2261         value = ((void *)s->base) + le16_to_cpu(s->here->e_value_offs);
2262         return !memcmp(value, i->value, i->value_len);
2263 }
2264
2265 static struct buffer_head *ext4_xattr_get_block(struct inode *inode)
2266 {
2267         struct buffer_head *bh;
2268         int error;
2269
2270         if (!EXT4_I(inode)->i_file_acl)
2271                 return NULL;
2272         bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
2273         if (IS_ERR(bh))
2274                 return bh;
2275         error = ext4_xattr_check_block(inode, bh);
2276         if (error) {
2277                 brelse(bh);
2278                 return ERR_PTR(error);
2279         }
2280         return bh;
2281 }
2282
2283 /*
2284  * ext4_xattr_set_handle()
2285  *
2286  * Create, replace or remove an extended attribute for this inode.  Value
2287  * is NULL to remove an existing extended attribute, and non-NULL to
2288  * either replace an existing extended attribute, or create a new extended
2289  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
2290  * specify that an extended attribute must exist and must not exist
2291  * previous to the call, respectively.
2292  *
2293  * Returns 0, or a negative error number on failure.
2294  */
2295 int
2296 ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
2297                       const char *name, const void *value, size_t value_len,
2298                       int flags)
2299 {
2300         struct ext4_xattr_info i = {
2301                 .name_index = name_index,
2302                 .name = name,
2303                 .value = value,
2304                 .value_len = value_len,
2305                 .in_inode = 0,
2306         };
2307         struct ext4_xattr_ibody_find is = {
2308                 .s = { .not_found = -ENODATA, },
2309         };
2310         struct ext4_xattr_block_find bs = {
2311                 .s = { .not_found = -ENODATA, },
2312         };
2313         int no_expand;
2314         int error;
2315
2316         if (!name)
2317                 return -EINVAL;
2318         if (strlen(name) > 255)
2319                 return -ERANGE;
2320
2321         ext4_write_lock_xattr(inode, &no_expand);
2322
2323         /* Check journal credits under write lock. */
2324         if (ext4_handle_valid(handle)) {
2325                 struct buffer_head *bh;
2326                 int credits;
2327
2328                 bh = ext4_xattr_get_block(inode);
2329                 if (IS_ERR(bh)) {
2330                         error = PTR_ERR(bh);
2331                         goto cleanup;
2332                 }
2333
2334                 credits = __ext4_xattr_set_credits(inode->i_sb, inode, bh,
2335                                                    value_len,
2336                                                    flags & XATTR_CREATE);
2337                 brelse(bh);
2338
2339                 if (jbd2_handle_buffer_credits(handle) < credits) {
2340                         error = -ENOSPC;
2341                         goto cleanup;
2342                 }
2343                 WARN_ON_ONCE(!(current->flags & PF_MEMALLOC_NOFS));
2344         }
2345
2346         error = ext4_reserve_inode_write(handle, inode, &is.iloc);
2347         if (error)
2348                 goto cleanup;
2349
2350         if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) {
2351                 struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
2352                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
2353                 ext4_clear_inode_state(inode, EXT4_STATE_NEW);
2354         }
2355
2356         error = ext4_xattr_ibody_find(inode, &i, &is);
2357         if (error)
2358                 goto cleanup;
2359         if (is.s.not_found)
2360                 error = ext4_xattr_block_find(inode, &i, &bs);
2361         if (error)
2362                 goto cleanup;
2363         if (is.s.not_found && bs.s.not_found) {
2364                 error = -ENODATA;
2365                 if (flags & XATTR_REPLACE)
2366                         goto cleanup;
2367                 error = 0;
2368                 if (!value)
2369                         goto cleanup;
2370         } else {
2371                 error = -EEXIST;
2372                 if (flags & XATTR_CREATE)
2373                         goto cleanup;
2374         }
2375
2376         if (!value) {
2377                 if (!is.s.not_found)
2378                         error = ext4_xattr_ibody_set(handle, inode, &i, &is);
2379                 else if (!bs.s.not_found)
2380                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
2381         } else {
2382                 error = 0;
2383                 /* Xattr value did not change? Save us some work and bail out */
2384                 if (!is.s.not_found && ext4_xattr_value_same(&is.s, &i))
2385                         goto cleanup;
2386                 if (!bs.s.not_found && ext4_xattr_value_same(&bs.s, &i))
2387                         goto cleanup;
2388
2389                 if (ext4_has_feature_ea_inode(inode->i_sb) &&
2390                     (EXT4_XATTR_SIZE(i.value_len) >
2391                         EXT4_XATTR_MIN_LARGE_EA_SIZE(inode->i_sb->s_blocksize)))
2392                         i.in_inode = 1;
2393 retry_inode:
2394                 error = ext4_xattr_ibody_set(handle, inode, &i, &is);
2395                 if (!error && !bs.s.not_found) {
2396                         i.value = NULL;
2397                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
2398                 } else if (error == -ENOSPC) {
2399                         if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
2400                                 brelse(bs.bh);
2401                                 bs.bh = NULL;
2402                                 error = ext4_xattr_block_find(inode, &i, &bs);
2403                                 if (error)
2404                                         goto cleanup;
2405                         }
2406                         error = ext4_xattr_block_set(handle, inode, &i, &bs);
2407                         if (!error && !is.s.not_found) {
2408                                 i.value = NULL;
2409                                 error = ext4_xattr_ibody_set(handle, inode, &i,
2410                                                              &is);
2411                         } else if (error == -ENOSPC) {
2412                                 /*
2413                                  * Xattr does not fit in the block, store at
2414                                  * external inode if possible.
2415                                  */
2416                                 if (ext4_has_feature_ea_inode(inode->i_sb) &&
2417                                     i.value_len && !i.in_inode) {
2418                                         i.in_inode = 1;
2419                                         goto retry_inode;
2420                                 }
2421                         }
2422                 }
2423         }
2424         if (!error) {
2425                 ext4_xattr_update_super_block(handle, inode->i_sb);
2426                 inode->i_ctime = current_time(inode);
2427                 inode_inc_iversion(inode);
2428                 if (!value)
2429                         no_expand = 0;
2430                 error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
2431                 /*
2432                  * The bh is consumed by ext4_mark_iloc_dirty, even with
2433                  * error != 0.
2434                  */
2435                 is.iloc.bh = NULL;
2436                 if (IS_SYNC(inode))
2437                         ext4_handle_sync(handle);
2438         }
2439         ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_XATTR, handle);
2440
2441 cleanup:
2442         brelse(is.iloc.bh);
2443         brelse(bs.bh);
2444         ext4_write_unlock_xattr(inode, &no_expand);
2445         return error;
2446 }
2447
2448 int ext4_xattr_set_credits(struct inode *inode, size_t value_len,
2449                            bool is_create, int *credits)
2450 {
2451         struct buffer_head *bh;
2452         int err;
2453
2454         *credits = 0;
2455
2456         if (!EXT4_SB(inode->i_sb)->s_journal)
2457                 return 0;
2458
2459         down_read(&EXT4_I(inode)->xattr_sem);
2460
2461         bh = ext4_xattr_get_block(inode);
2462         if (IS_ERR(bh)) {
2463                 err = PTR_ERR(bh);
2464         } else {
2465                 *credits = __ext4_xattr_set_credits(inode->i_sb, inode, bh,
2466                                                     value_len, is_create);
2467                 brelse(bh);
2468                 err = 0;
2469         }
2470
2471         up_read(&EXT4_I(inode)->xattr_sem);
2472         return err;
2473 }
2474
2475 /*
2476  * ext4_xattr_set()
2477  *
2478  * Like ext4_xattr_set_handle, but start from an inode. This extended
2479  * attribute modification is a filesystem transaction by itself.
2480  *
2481  * Returns 0, or a negative error number on failure.
2482  */
2483 int
2484 ext4_xattr_set(struct inode *inode, int name_index, const char *name,
2485                const void *value, size_t value_len, int flags)
2486 {
2487         handle_t *handle;
2488         struct super_block *sb = inode->i_sb;
2489         int error, retries = 0;
2490         int credits;
2491
2492         error = dquot_initialize(inode);
2493         if (error)
2494                 return error;
2495
2496 retry:
2497         error = ext4_xattr_set_credits(inode, value_len, flags & XATTR_CREATE,
2498                                        &credits);
2499         if (error)
2500                 return error;
2501
2502         handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
2503         if (IS_ERR(handle)) {
2504                 error = PTR_ERR(handle);
2505         } else {
2506                 int error2;
2507
2508                 error = ext4_xattr_set_handle(handle, inode, name_index, name,
2509                                               value, value_len, flags);
2510                 error2 = ext4_journal_stop(handle);
2511                 if (error == -ENOSPC &&
2512                     ext4_should_retry_alloc(sb, &retries))
2513                         goto retry;
2514                 if (error == 0)
2515                         error = error2;
2516         }
2517         ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_XATTR, NULL);
2518
2519         return error;
2520 }
2521
2522 /*
2523  * Shift the EA entries in the inode to create space for the increased
2524  * i_extra_isize.
2525  */
2526 static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
2527                                      int value_offs_shift, void *to,
2528                                      void *from, size_t n)
2529 {
2530         struct ext4_xattr_entry *last = entry;
2531         int new_offs;
2532
2533         /* We always shift xattr headers further thus offsets get lower */
2534         BUG_ON(value_offs_shift > 0);
2535
2536         /* Adjust the value offsets of the entries */
2537         for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
2538                 if (!last->e_value_inum && last->e_value_size) {
2539                         new_offs = le16_to_cpu(last->e_value_offs) +
2540                                                         value_offs_shift;
2541                         last->e_value_offs = cpu_to_le16(new_offs);
2542                 }
2543         }
2544         /* Shift the entries by n bytes */
2545         memmove(to, from, n);
2546 }
2547
2548 /*
2549  * Move xattr pointed to by 'entry' from inode into external xattr block
2550  */
2551 static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode,
2552                                     struct ext4_inode *raw_inode,
2553                                     struct ext4_xattr_entry *entry)
2554 {
2555         struct ext4_xattr_ibody_find *is = NULL;
2556         struct ext4_xattr_block_find *bs = NULL;
2557         char *buffer = NULL, *b_entry_name = NULL;
2558         size_t value_size = le32_to_cpu(entry->e_value_size);
2559         struct ext4_xattr_info i = {
2560                 .value = NULL,
2561                 .value_len = 0,
2562                 .name_index = entry->e_name_index,
2563                 .in_inode = !!entry->e_value_inum,
2564         };
2565         struct ext4_xattr_ibody_header *header = IHDR(inode, raw_inode);
2566         int error;
2567
2568         is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
2569         bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
2570         buffer = kvmalloc(value_size, GFP_NOFS);
2571         b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
2572         if (!is || !bs || !buffer || !b_entry_name) {
2573                 error = -ENOMEM;
2574                 goto out;
2575         }
2576
2577         is->s.not_found = -ENODATA;
2578         bs->s.not_found = -ENODATA;
2579         is->iloc.bh = NULL;
2580         bs->bh = NULL;
2581
2582         /* Save the entry name and the entry value */
2583         if (entry->e_value_inum) {
2584                 error = ext4_xattr_inode_get(inode, entry, buffer, value_size);
2585                 if (error)
2586                         goto out;
2587         } else {
2588                 size_t value_offs = le16_to_cpu(entry->e_value_offs);
2589                 memcpy(buffer, (void *)IFIRST(header) + value_offs, value_size);
2590         }
2591
2592         memcpy(b_entry_name, entry->e_name, entry->e_name_len);
2593         b_entry_name[entry->e_name_len] = '\0';
2594         i.name = b_entry_name;
2595
2596         error = ext4_get_inode_loc(inode, &is->iloc);
2597         if (error)
2598                 goto out;
2599
2600         error = ext4_xattr_ibody_find(inode, &i, is);
2601         if (error)
2602                 goto out;
2603
2604         /* Remove the chosen entry from the inode */
2605         error = ext4_xattr_ibody_set(handle, inode, &i, is);
2606         if (error)
2607                 goto out;
2608
2609         i.value = buffer;
2610         i.value_len = value_size;
2611         error = ext4_xattr_block_find(inode, &i, bs);
2612         if (error)
2613                 goto out;
2614
2615         /* Add entry which was removed from the inode into the block */
2616         error = ext4_xattr_block_set(handle, inode, &i, bs);
2617         if (error)
2618                 goto out;
2619         error = 0;
2620 out:
2621         kfree(b_entry_name);
2622         kvfree(buffer);
2623         if (is)
2624                 brelse(is->iloc.bh);
2625         if (bs)
2626                 brelse(bs->bh);
2627         kfree(is);
2628         kfree(bs);
2629
2630         return error;
2631 }
2632
2633 static int ext4_xattr_make_inode_space(handle_t *handle, struct inode *inode,
2634                                        struct ext4_inode *raw_inode,
2635                                        int isize_diff, size_t ifree,
2636                                        size_t bfree, int *total_ino)
2637 {
2638         struct ext4_xattr_ibody_header *header = IHDR(inode, raw_inode);
2639         struct ext4_xattr_entry *small_entry;
2640         struct ext4_xattr_entry *entry;
2641         struct ext4_xattr_entry *last;
2642         unsigned int entry_size;        /* EA entry size */
2643         unsigned int total_size;        /* EA entry size + value size */
2644         unsigned int min_total_size;
2645         int error;
2646
2647         while (isize_diff > ifree) {
2648                 entry = NULL;
2649                 small_entry = NULL;
2650                 min_total_size = ~0U;
2651                 last = IFIRST(header);
2652                 /* Find the entry best suited to be pushed into EA block */
2653                 for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
2654                         /* never move system.data out of the inode */
2655                         if ((last->e_name_len == 4) &&
2656                             (last->e_name_index == EXT4_XATTR_INDEX_SYSTEM) &&
2657                             !memcmp(last->e_name, "data", 4))
2658                                 continue;
2659                         total_size = EXT4_XATTR_LEN(last->e_name_len);
2660                         if (!last->e_value_inum)
2661                                 total_size += EXT4_XATTR_SIZE(
2662                                                le32_to_cpu(last->e_value_size));
2663                         if (total_size <= bfree &&
2664                             total_size < min_total_size) {
2665                                 if (total_size + ifree < isize_diff) {
2666                                         small_entry = last;
2667                                 } else {
2668                                         entry = last;
2669                                         min_total_size = total_size;
2670                                 }
2671                         }
2672                 }
2673
2674                 if (entry == NULL) {
2675                         if (small_entry == NULL)
2676                                 return -ENOSPC;
2677                         entry = small_entry;
2678                 }
2679
2680                 entry_size = EXT4_XATTR_LEN(entry->e_name_len);
2681                 total_size = entry_size;
2682                 if (!entry->e_value_inum)
2683                         total_size += EXT4_XATTR_SIZE(
2684                                               le32_to_cpu(entry->e_value_size));
2685                 error = ext4_xattr_move_to_block(handle, inode, raw_inode,
2686                                                  entry);
2687                 if (error)
2688                         return error;
2689
2690                 *total_ino -= entry_size;
2691                 ifree += total_size;
2692                 bfree -= total_size;
2693         }
2694
2695         return 0;
2696 }
2697
2698 /*
2699  * Expand an inode by new_extra_isize bytes when EAs are present.
2700  * Returns 0 on success or negative error number on failure.
2701  */
2702 int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
2703                                struct ext4_inode *raw_inode, handle_t *handle)
2704 {
2705         struct ext4_xattr_ibody_header *header;
2706         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
2707         static unsigned int mnt_count;
2708         size_t min_offs;
2709         size_t ifree, bfree;
2710         int total_ino;
2711         void *base, *end;
2712         int error = 0, tried_min_extra_isize = 0;
2713         int s_min_extra_isize = le16_to_cpu(sbi->s_es->s_min_extra_isize);
2714         int isize_diff; /* How much do we need to grow i_extra_isize */
2715
2716 retry:
2717         isize_diff = new_extra_isize - EXT4_I(inode)->i_extra_isize;
2718         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
2719                 return 0;
2720
2721         header = IHDR(inode, raw_inode);
2722
2723         /*
2724          * Check if enough free space is available in the inode to shift the
2725          * entries ahead by new_extra_isize.
2726          */
2727
2728         base = IFIRST(header);
2729         end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
2730         min_offs = end - base;
2731         total_ino = sizeof(struct ext4_xattr_ibody_header) + sizeof(u32);
2732
2733         error = xattr_check_inode(inode, header, end);
2734         if (error)
2735                 goto cleanup;
2736
2737         ifree = ext4_xattr_free_space(base, &min_offs, base, &total_ino);
2738         if (ifree >= isize_diff)
2739                 goto shift;
2740
2741         /*
2742          * Enough free space isn't available in the inode, check if
2743          * EA block can hold new_extra_isize bytes.
2744          */
2745         if (EXT4_I(inode)->i_file_acl) {
2746                 struct buffer_head *bh;
2747
2748                 bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
2749                 if (IS_ERR(bh)) {
2750                         error = PTR_ERR(bh);
2751                         goto cleanup;
2752                 }
2753                 error = ext4_xattr_check_block(inode, bh);
2754                 if (error) {
2755                         brelse(bh);
2756                         goto cleanup;
2757                 }
2758                 base = BHDR(bh);
2759                 end = bh->b_data + bh->b_size;
2760                 min_offs = end - base;
2761                 bfree = ext4_xattr_free_space(BFIRST(bh), &min_offs, base,
2762                                               NULL);
2763                 brelse(bh);
2764                 if (bfree + ifree < isize_diff) {
2765                         if (!tried_min_extra_isize && s_min_extra_isize) {
2766                                 tried_min_extra_isize++;
2767                                 new_extra_isize = s_min_extra_isize;
2768                                 goto retry;
2769                         }
2770                         error = -ENOSPC;
2771                         goto cleanup;
2772                 }
2773         } else {
2774                 bfree = inode->i_sb->s_blocksize;
2775         }
2776
2777         error = ext4_xattr_make_inode_space(handle, inode, raw_inode,
2778                                             isize_diff, ifree, bfree,
2779                                             &total_ino);
2780         if (error) {
2781                 if (error == -ENOSPC && !tried_min_extra_isize &&
2782                     s_min_extra_isize) {
2783                         tried_min_extra_isize++;
2784                         new_extra_isize = s_min_extra_isize;
2785                         goto retry;
2786                 }
2787                 goto cleanup;
2788         }
2789 shift:
2790         /* Adjust the offsets and shift the remaining entries ahead */
2791         ext4_xattr_shift_entries(IFIRST(header), EXT4_I(inode)->i_extra_isize
2792                         - new_extra_isize, (void *)raw_inode +
2793                         EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
2794                         (void *)header, total_ino);
2795         EXT4_I(inode)->i_extra_isize = new_extra_isize;
2796
2797 cleanup:
2798         if (error && (mnt_count != le16_to_cpu(sbi->s_es->s_mnt_count))) {
2799                 ext4_warning(inode->i_sb, "Unable to expand inode %lu. Delete some EAs or run e2fsck.",
2800                              inode->i_ino);
2801                 mnt_count = le16_to_cpu(sbi->s_es->s_mnt_count);
2802         }
2803         return error;
2804 }
2805
2806 #define EIA_INCR 16 /* must be 2^n */
2807 #define EIA_MASK (EIA_INCR - 1)
2808
2809 /* Add the large xattr @inode into @ea_inode_array for deferred iput().
2810  * If @ea_inode_array is new or full it will be grown and the old
2811  * contents copied over.
2812  */
2813 static int
2814 ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
2815                         struct inode *inode)
2816 {
2817         if (*ea_inode_array == NULL) {
2818                 /*
2819                  * Start with 15 inodes, so it fits into a power-of-two size.
2820                  * If *ea_inode_array is NULL, this is essentially offsetof()
2821                  */
2822                 (*ea_inode_array) =
2823                         kmalloc(offsetof(struct ext4_xattr_inode_array,
2824                                          inodes[EIA_MASK]),
2825                                 GFP_NOFS);
2826                 if (*ea_inode_array == NULL)
2827                         return -ENOMEM;
2828                 (*ea_inode_array)->count = 0;
2829         } else if (((*ea_inode_array)->count & EIA_MASK) == EIA_MASK) {
2830                 /* expand the array once all 15 + n * 16 slots are full */
2831                 struct ext4_xattr_inode_array *new_array = NULL;
2832                 int count = (*ea_inode_array)->count;
2833
2834                 /* if new_array is NULL, this is essentially offsetof() */
2835                 new_array = kmalloc(
2836                                 offsetof(struct ext4_xattr_inode_array,
2837                                          inodes[count + EIA_INCR]),
2838                                 GFP_NOFS);
2839                 if (new_array == NULL)
2840                         return -ENOMEM;
2841                 memcpy(new_array, *ea_inode_array,
2842                        offsetof(struct ext4_xattr_inode_array, inodes[count]));
2843                 kfree(*ea_inode_array);
2844                 *ea_inode_array = new_array;
2845         }
2846         (*ea_inode_array)->inodes[(*ea_inode_array)->count++] = inode;
2847         return 0;
2848 }
2849
2850 /*
2851  * ext4_xattr_delete_inode()
2852  *
2853  * Free extended attribute resources associated with this inode. Traverse
2854  * all entries and decrement reference on any xattr inodes associated with this
2855  * inode. This is called immediately before an inode is freed. We have exclusive
2856  * access to the inode. If an orphan inode is deleted it will also release its
2857  * references on xattr block and xattr inodes.
2858  */
2859 int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
2860                             struct ext4_xattr_inode_array **ea_inode_array,
2861                             int extra_credits)
2862 {
2863         struct buffer_head *bh = NULL;
2864         struct ext4_xattr_ibody_header *header;
2865         struct ext4_iloc iloc = { .bh = NULL };
2866         struct ext4_xattr_entry *entry;
2867         struct inode *ea_inode;
2868         int error;
2869
2870         error = ext4_journal_ensure_credits(handle, extra_credits,
2871                         ext4_free_metadata_revoke_credits(inode->i_sb, 1));
2872         if (error < 0) {
2873                 EXT4_ERROR_INODE(inode, "ensure credits (error %d)", error);
2874                 goto cleanup;
2875         }
2876
2877         if (ext4_has_feature_ea_inode(inode->i_sb) &&
2878             ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
2879
2880                 error = ext4_get_inode_loc(inode, &iloc);
2881                 if (error) {
2882                         EXT4_ERROR_INODE(inode, "inode loc (error %d)", error);
2883                         goto cleanup;
2884                 }
2885
2886                 error = ext4_journal_get_write_access(handle, inode->i_sb,
2887                                                 iloc.bh, EXT4_JTR_NONE);
2888                 if (error) {
2889                         EXT4_ERROR_INODE(inode, "write access (error %d)",
2890                                          error);
2891                         goto cleanup;
2892                 }
2893
2894                 header = IHDR(inode, ext4_raw_inode(&iloc));
2895                 if (header->h_magic == cpu_to_le32(EXT4_XATTR_MAGIC))
2896                         ext4_xattr_inode_dec_ref_all(handle, inode, iloc.bh,
2897                                                      IFIRST(header),
2898                                                      false /* block_csum */,
2899                                                      ea_inode_array,
2900                                                      extra_credits,
2901                                                      false /* skip_quota */);
2902         }
2903
2904         if (EXT4_I(inode)->i_file_acl) {
2905                 bh = ext4_sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl, REQ_PRIO);
2906                 if (IS_ERR(bh)) {
2907                         error = PTR_ERR(bh);
2908                         if (error == -EIO) {
2909                                 EXT4_ERROR_INODE_ERR(inode, EIO,
2910                                                      "block %llu read error",
2911                                                      EXT4_I(inode)->i_file_acl);
2912                         }
2913                         bh = NULL;
2914                         goto cleanup;
2915                 }
2916                 error = ext4_xattr_check_block(inode, bh);
2917                 if (error)
2918                         goto cleanup;
2919
2920                 if (ext4_has_feature_ea_inode(inode->i_sb)) {
2921                         for (entry = BFIRST(bh); !IS_LAST_ENTRY(entry);
2922                              entry = EXT4_XATTR_NEXT(entry)) {
2923                                 if (!entry->e_value_inum)
2924                                         continue;
2925                                 error = ext4_xattr_inode_iget(inode,
2926                                               le32_to_cpu(entry->e_value_inum),
2927                                               le32_to_cpu(entry->e_hash),
2928                                               &ea_inode);
2929                                 if (error)
2930                                         continue;
2931                                 ext4_xattr_inode_free_quota(inode, ea_inode,
2932                                               le32_to_cpu(entry->e_value_size));
2933                                 iput(ea_inode);
2934                         }
2935
2936                 }
2937
2938                 ext4_xattr_release_block(handle, inode, bh, ea_inode_array,
2939                                          extra_credits);
2940                 /*
2941                  * Update i_file_acl value in the same transaction that releases
2942                  * block.
2943                  */
2944                 EXT4_I(inode)->i_file_acl = 0;
2945                 error = ext4_mark_inode_dirty(handle, inode);
2946                 if (error) {
2947                         EXT4_ERROR_INODE(inode, "mark inode dirty (error %d)",
2948                                          error);
2949                         goto cleanup;
2950                 }
2951                 ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_XATTR, handle);
2952         }
2953         error = 0;
2954 cleanup:
2955         brelse(iloc.bh);
2956         brelse(bh);
2957         return error;
2958 }
2959
2960 void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *ea_inode_array)
2961 {
2962         int idx;
2963
2964         if (ea_inode_array == NULL)
2965                 return;
2966
2967         for (idx = 0; idx < ea_inode_array->count; ++idx)
2968                 iput(ea_inode_array->inodes[idx]);
2969         kfree(ea_inode_array);
2970 }
2971
2972 /*
2973  * ext4_xattr_block_cache_insert()
2974  *
2975  * Create a new entry in the extended attribute block cache, and insert
2976  * it unless such an entry is already in the cache.
2977  *
2978  * Returns 0, or a negative error number on failure.
2979  */
2980 static void
2981 ext4_xattr_block_cache_insert(struct mb_cache *ea_block_cache,
2982                               struct buffer_head *bh)
2983 {
2984         struct ext4_xattr_header *header = BHDR(bh);
2985         __u32 hash = le32_to_cpu(header->h_hash);
2986         int reusable = le32_to_cpu(header->h_refcount) <
2987                        EXT4_XATTR_REFCOUNT_MAX;
2988         int error;
2989
2990         if (!ea_block_cache)
2991                 return;
2992         error = mb_cache_entry_create(ea_block_cache, GFP_NOFS, hash,
2993                                       bh->b_blocknr, reusable);
2994         if (error) {
2995                 if (error == -EBUSY)
2996                         ea_bdebug(bh, "already in cache");
2997         } else
2998                 ea_bdebug(bh, "inserting [%x]", (int)hash);
2999 }
3000
3001 /*
3002  * ext4_xattr_cmp()
3003  *
3004  * Compare two extended attribute blocks for equality.
3005  *
3006  * Returns 0 if the blocks are equal, 1 if they differ, and
3007  * a negative error number on errors.
3008  */
3009 static int
3010 ext4_xattr_cmp(struct ext4_xattr_header *header1,
3011                struct ext4_xattr_header *header2)
3012 {
3013         struct ext4_xattr_entry *entry1, *entry2;
3014
3015         entry1 = ENTRY(header1+1);
3016         entry2 = ENTRY(header2+1);
3017         while (!IS_LAST_ENTRY(entry1)) {
3018                 if (IS_LAST_ENTRY(entry2))
3019                         return 1;
3020                 if (entry1->e_hash != entry2->e_hash ||
3021                     entry1->e_name_index != entry2->e_name_index ||
3022                     entry1->e_name_len != entry2->e_name_len ||
3023                     entry1->e_value_size != entry2->e_value_size ||
3024                     entry1->e_value_inum != entry2->e_value_inum ||
3025                     memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
3026                         return 1;
3027                 if (!entry1->e_value_inum &&
3028                     memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
3029                            (char *)header2 + le16_to_cpu(entry2->e_value_offs),
3030                            le32_to_cpu(entry1->e_value_size)))
3031                         return 1;
3032
3033                 entry1 = EXT4_XATTR_NEXT(entry1);
3034                 entry2 = EXT4_XATTR_NEXT(entry2);
3035         }
3036         if (!IS_LAST_ENTRY(entry2))
3037                 return 1;
3038         return 0;
3039 }
3040
3041 /*
3042  * ext4_xattr_block_cache_find()
3043  *
3044  * Find an identical extended attribute block.
3045  *
3046  * Returns a pointer to the block found, or NULL if such a block was
3047  * not found or an error occurred.
3048  */
3049 static struct buffer_head *
3050 ext4_xattr_block_cache_find(struct inode *inode,
3051                             struct ext4_xattr_header *header,
3052                             struct mb_cache_entry **pce)
3053 {
3054         __u32 hash = le32_to_cpu(header->h_hash);
3055         struct mb_cache_entry *ce;
3056         struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
3057
3058         if (!ea_block_cache)
3059                 return NULL;
3060         if (!header->h_hash)
3061                 return NULL;  /* never share */
3062         ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
3063         ce = mb_cache_entry_find_first(ea_block_cache, hash);
3064         while (ce) {
3065                 struct buffer_head *bh;
3066
3067                 bh = ext4_sb_bread(inode->i_sb, ce->e_value, REQ_PRIO);
3068                 if (IS_ERR(bh)) {
3069                         if (PTR_ERR(bh) == -ENOMEM)
3070                                 return NULL;
3071                         bh = NULL;
3072                         EXT4_ERROR_INODE(inode, "block %lu read error",
3073                                          (unsigned long)ce->e_value);
3074                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
3075                         *pce = ce;
3076                         return bh;
3077                 }
3078                 brelse(bh);
3079                 ce = mb_cache_entry_find_next(ea_block_cache, ce);
3080         }
3081         return NULL;
3082 }
3083
3084 #define NAME_HASH_SHIFT 5
3085 #define VALUE_HASH_SHIFT 16
3086
3087 /*
3088  * ext4_xattr_hash_entry()
3089  *
3090  * Compute the hash of an extended attribute.
3091  */
3092 static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value,
3093                                     size_t value_count)
3094 {
3095         __u32 hash = 0;
3096
3097         while (name_len--) {
3098                 hash = (hash << NAME_HASH_SHIFT) ^
3099                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
3100                        (unsigned char)*name++;
3101         }
3102         while (value_count--) {
3103                 hash = (hash << VALUE_HASH_SHIFT) ^
3104                        (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
3105                        le32_to_cpu(*value++);
3106         }
3107         return cpu_to_le32(hash);
3108 }
3109
3110 /*
3111  * ext4_xattr_hash_entry_signed()
3112  *
3113  * Compute the hash of an extended attribute incorrectly.
3114  */
3115 static __le32 ext4_xattr_hash_entry_signed(char *name, size_t name_len, __le32 *value, size_t value_count)
3116 {
3117         __u32 hash = 0;
3118
3119         while (name_len--) {
3120                 hash = (hash << NAME_HASH_SHIFT) ^
3121                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
3122                        (signed char)*name++;
3123         }
3124         while (value_count--) {
3125                 hash = (hash << VALUE_HASH_SHIFT) ^
3126                        (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
3127                        le32_to_cpu(*value++);
3128         }
3129         return cpu_to_le32(hash);
3130 }
3131
3132 #undef NAME_HASH_SHIFT
3133 #undef VALUE_HASH_SHIFT
3134
3135 #define BLOCK_HASH_SHIFT 16
3136
3137 /*
3138  * ext4_xattr_rehash()
3139  *
3140  * Re-compute the extended attribute hash value after an entry has changed.
3141  */
3142 static void ext4_xattr_rehash(struct ext4_xattr_header *header)
3143 {
3144         struct ext4_xattr_entry *here;
3145         __u32 hash = 0;
3146
3147         here = ENTRY(header+1);
3148         while (!IS_LAST_ENTRY(here)) {
3149                 if (!here->e_hash) {
3150                         /* Block is not shared if an entry's hash value == 0 */
3151                         hash = 0;
3152                         break;
3153                 }
3154                 hash = (hash << BLOCK_HASH_SHIFT) ^
3155                        (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
3156                        le32_to_cpu(here->e_hash);
3157                 here = EXT4_XATTR_NEXT(here);
3158         }
3159         header->h_hash = cpu_to_le32(hash);
3160 }
3161
3162 #undef BLOCK_HASH_SHIFT
3163
3164 #define HASH_BUCKET_BITS        10
3165
3166 struct mb_cache *
3167 ext4_xattr_create_cache(void)
3168 {
3169         return mb_cache_create(HASH_BUCKET_BITS);
3170 }
3171
3172 void ext4_xattr_destroy_cache(struct mb_cache *cache)
3173 {
3174         if (cache)
3175                 mb_cache_destroy(cache);
3176 }
3177