1 /* 2 * linux/fs/ext2/xattr.c 3 * 4 * Copyright (C) 2001-2003 Andreas Gruenbacher <agruen@suse.de> 5 * 6 * Fix by Harrison Xing <harrison@mountainviewdata.com>. 7 * Extended attributes for symlinks and special files added per 8 * suggestion of Luka Renko <luka.renko@hermes.si>. 9 * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>, 10 * Red Hat Inc. 11 * 12 */ 13 14 /* 15 * Extended attributes are stored on disk blocks allocated outside of 16 * any inode. The i_file_acl field is then made to point to this allocated 17 * block. If all extended attributes of an inode are identical, these 18 * inodes may share the same extended attribute block. Such situations 19 * are automatically detected by keeping a cache of recent attribute block 20 * numbers and hashes over the block's contents in memory. 21 * 22 * 23 * Extended attribute block layout: 24 * 25 * +------------------+ 26 * | header | 27 * | entry 1 | | 28 * | entry 2 | | growing downwards 29 * | entry 3 | v 30 * | four null bytes | 31 * | . . . | 32 * | value 1 | ^ 33 * | value 3 | | growing upwards 34 * | value 2 | | 35 * +------------------+ 36 * 37 * The block header is followed by multiple entry descriptors. These entry 38 * descriptors are variable in size, and alligned to EXT2_XATTR_PAD 39 * byte boundaries. The entry descriptors are sorted by attribute name, 40 * so that two extended attribute blocks can be compared efficiently. 41 * 42 * Attribute values are aligned to the end of the block, stored in 43 * no specific order. They are also padded to EXT2_XATTR_PAD byte 44 * boundaries. No additional gaps are left between them. 45 * 46 * Locking strategy 47 * ---------------- 48 * EXT2_I(inode)->i_file_acl is protected by EXT2_I(inode)->xattr_sem. 49 * EA blocks are only changed if they are exclusive to an inode, so 50 * holding xattr_sem also means that nothing but the EA block's reference 51 * count will change. Multiple writers to an EA block are synchronized 52 * by the bh lock. No more than a single bh lock is held at any time 53 * to avoid deadlocks. 54 */ 55 56 #include <linux/buffer_head.h> 57 #include <linux/module.h> 58 #include <linux/init.h> 59 #include <linux/slab.h> 60 #include <linux/mbcache.h> 61 #include <linux/quotaops.h> 62 #include <linux/rwsem.h> 63 #include "ext2.h" 64 #include "xattr.h" 65 #include "acl.h" 66 67 #define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data)) 68 #define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr)) 69 #define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1) 70 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0) 71 72 #ifdef EXT2_XATTR_DEBUG 73 # define ea_idebug(inode, f...) do { \ 74 printk(KERN_DEBUG "inode %s:%ld: ", \ 75 inode->i_sb->s_id, inode->i_ino); \ 76 printk(f); \ 77 printk("\n"); \ 78 } while (0) 79 # define ea_bdebug(bh, f...) do { \ 80 char b[BDEVNAME_SIZE]; \ 81 printk(KERN_DEBUG "block %s:%lu: ", \ 82 bdevname(bh->b_bdev, b), \ 83 (unsigned long) bh->b_blocknr); \ 84 printk(f); \ 85 printk("\n"); \ 86 } while (0) 87 #else 88 # define ea_idebug(f...) 89 # define ea_bdebug(f...) 90 #endif 91 92 static int ext2_xattr_set2(struct inode *, struct buffer_head *, 93 struct ext2_xattr_header *); 94 95 static int ext2_xattr_cache_insert(struct buffer_head *); 96 static struct buffer_head *ext2_xattr_cache_find(struct inode *, 97 struct ext2_xattr_header *); 98 static void ext2_xattr_rehash(struct ext2_xattr_header *, 99 struct ext2_xattr_entry *); 100 101 static struct mb_cache *ext2_xattr_cache; 102 103 static struct xattr_handler *ext2_xattr_handler_map[] = { 104 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler, 105 #ifdef CONFIG_EXT2_FS_POSIX_ACL 106 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &ext2_xattr_acl_access_handler, 107 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext2_xattr_acl_default_handler, 108 #endif 109 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler, 110 #ifdef CONFIG_EXT2_FS_SECURITY 111 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler, 112 #endif 113 }; 114 115 struct xattr_handler *ext2_xattr_handlers[] = { 116 &ext2_xattr_user_handler, 117 &ext2_xattr_trusted_handler, 118 #ifdef CONFIG_EXT2_FS_POSIX_ACL 119 &ext2_xattr_acl_access_handler, 120 &ext2_xattr_acl_default_handler, 121 #endif 122 #ifdef CONFIG_EXT2_FS_SECURITY 123 &ext2_xattr_security_handler, 124 #endif 125 NULL 126 }; 127 128 static inline struct xattr_handler * 129 ext2_xattr_handler(int name_index) 130 { 131 struct xattr_handler *handler = NULL; 132 133 if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map)) 134 handler = ext2_xattr_handler_map[name_index]; 135 return handler; 136 } 137 138 /* 139 * ext2_xattr_get() 140 * 141 * Copy an extended attribute into the buffer 142 * provided, or compute the buffer size required. 143 * Buffer is NULL to compute the size of the buffer required. 144 * 145 * Returns a negative error number on failure, or the number of bytes 146 * used / required on success. 147 */ 148 int 149 ext2_xattr_get(struct inode *inode, int name_index, const char *name, 150 void *buffer, size_t buffer_size) 151 { 152 struct buffer_head *bh = NULL; 153 struct ext2_xattr_entry *entry; 154 size_t name_len, size; 155 char *end; 156 int error; 157 158 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld", 159 name_index, name, buffer, (long)buffer_size); 160 161 if (name == NULL) 162 return -EINVAL; 163 down_read(&EXT2_I(inode)->xattr_sem); 164 error = -ENODATA; 165 if (!EXT2_I(inode)->i_file_acl) 166 goto cleanup; 167 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); 168 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 169 error = -EIO; 170 if (!bh) 171 goto cleanup; 172 ea_bdebug(bh, "b_count=%d, refcount=%d", 173 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount)); 174 end = bh->b_data + bh->b_size; 175 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 176 HDR(bh)->h_blocks != cpu_to_le32(1)) { 177 bad_block: ext2_error(inode->i_sb, "ext2_xattr_get", 178 "inode %ld: bad block %d", inode->i_ino, 179 EXT2_I(inode)->i_file_acl); 180 error = -EIO; 181 goto cleanup; 182 } 183 /* find named attribute */ 184 name_len = strlen(name); 185 186 error = -ERANGE; 187 if (name_len > 255) 188 goto cleanup; 189 entry = FIRST_ENTRY(bh); 190 while (!IS_LAST_ENTRY(entry)) { 191 struct ext2_xattr_entry *next = 192 EXT2_XATTR_NEXT(entry); 193 if ((char *)next >= end) 194 goto bad_block; 195 if (name_index == entry->e_name_index && 196 name_len == entry->e_name_len && 197 memcmp(name, entry->e_name, name_len) == 0) 198 goto found; 199 entry = next; 200 } 201 /* Check the remaining name entries */ 202 while (!IS_LAST_ENTRY(entry)) { 203 struct ext2_xattr_entry *next = 204 EXT2_XATTR_NEXT(entry); 205 if ((char *)next >= end) 206 goto bad_block; 207 entry = next; 208 } 209 if (ext2_xattr_cache_insert(bh)) 210 ea_idebug(inode, "cache insert failed"); 211 error = -ENODATA; 212 goto cleanup; 213 found: 214 /* check the buffer size */ 215 if (entry->e_value_block != 0) 216 goto bad_block; 217 size = le32_to_cpu(entry->e_value_size); 218 if (size > inode->i_sb->s_blocksize || 219 le16_to_cpu(entry->e_value_offs) + size > inode->i_sb->s_blocksize) 220 goto bad_block; 221 222 if (ext2_xattr_cache_insert(bh)) 223 ea_idebug(inode, "cache insert failed"); 224 if (buffer) { 225 error = -ERANGE; 226 if (size > buffer_size) 227 goto cleanup; 228 /* return value of attribute */ 229 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs), 230 size); 231 } 232 error = size; 233 234 cleanup: 235 brelse(bh); 236 up_read(&EXT2_I(inode)->xattr_sem); 237 238 return error; 239 } 240 241 /* 242 * ext2_xattr_list() 243 * 244 * Copy a list of attribute names into the buffer 245 * provided, or compute the buffer size required. 246 * Buffer is NULL to compute the size of the buffer required. 247 * 248 * Returns a negative error number on failure, or the number of bytes 249 * used / required on success. 250 */ 251 static int 252 ext2_xattr_list(struct inode *inode, char *buffer, size_t buffer_size) 253 { 254 struct buffer_head *bh = NULL; 255 struct ext2_xattr_entry *entry; 256 char *end; 257 size_t rest = buffer_size; 258 int error; 259 260 ea_idebug(inode, "buffer=%p, buffer_size=%ld", 261 buffer, (long)buffer_size); 262 263 down_read(&EXT2_I(inode)->xattr_sem); 264 error = 0; 265 if (!EXT2_I(inode)->i_file_acl) 266 goto cleanup; 267 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); 268 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 269 error = -EIO; 270 if (!bh) 271 goto cleanup; 272 ea_bdebug(bh, "b_count=%d, refcount=%d", 273 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount)); 274 end = bh->b_data + bh->b_size; 275 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 276 HDR(bh)->h_blocks != cpu_to_le32(1)) { 277 bad_block: ext2_error(inode->i_sb, "ext2_xattr_list", 278 "inode %ld: bad block %d", inode->i_ino, 279 EXT2_I(inode)->i_file_acl); 280 error = -EIO; 281 goto cleanup; 282 } 283 284 /* check the on-disk data structure */ 285 entry = FIRST_ENTRY(bh); 286 while (!IS_LAST_ENTRY(entry)) { 287 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(entry); 288 289 if ((char *)next >= end) 290 goto bad_block; 291 entry = next; 292 } 293 if (ext2_xattr_cache_insert(bh)) 294 ea_idebug(inode, "cache insert failed"); 295 296 /* list the attribute names */ 297 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry); 298 entry = EXT2_XATTR_NEXT(entry)) { 299 struct xattr_handler *handler = 300 ext2_xattr_handler(entry->e_name_index); 301 302 if (handler) { 303 size_t size = handler->list(inode, buffer, rest, 304 entry->e_name, 305 entry->e_name_len); 306 if (buffer) { 307 if (size > rest) { 308 error = -ERANGE; 309 goto cleanup; 310 } 311 buffer += size; 312 } 313 rest -= size; 314 } 315 } 316 error = buffer_size - rest; /* total size */ 317 318 cleanup: 319 brelse(bh); 320 up_read(&EXT2_I(inode)->xattr_sem); 321 322 return error; 323 } 324 325 /* 326 * Inode operation listxattr() 327 * 328 * dentry->d_inode->i_mutex: don't care 329 */ 330 ssize_t 331 ext2_listxattr(struct dentry *dentry, char *buffer, size_t size) 332 { 333 return ext2_xattr_list(dentry->d_inode, buffer, size); 334 } 335 336 /* 337 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is 338 * not set, set it. 339 */ 340 static void ext2_xattr_update_super_block(struct super_block *sb) 341 { 342 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR)) 343 return; 344 345 lock_super(sb); 346 EXT2_SB(sb)->s_es->s_feature_compat |= 347 cpu_to_le32(EXT2_FEATURE_COMPAT_EXT_ATTR); 348 sb->s_dirt = 1; 349 mark_buffer_dirty(EXT2_SB(sb)->s_sbh); 350 unlock_super(sb); 351 } 352 353 /* 354 * ext2_xattr_set() 355 * 356 * Create, replace or remove an extended attribute for this inode. Buffer 357 * is NULL to remove an existing extended attribute, and non-NULL to 358 * either replace an existing extended attribute, or create a new extended 359 * attribute. The flags XATTR_REPLACE and XATTR_CREATE 360 * specify that an extended attribute must exist and must not exist 361 * previous to the call, respectively. 362 * 363 * Returns 0, or a negative error number on failure. 364 */ 365 int 366 ext2_xattr_set(struct inode *inode, int name_index, const char *name, 367 const void *value, size_t value_len, int flags) 368 { 369 struct super_block *sb = inode->i_sb; 370 struct buffer_head *bh = NULL; 371 struct ext2_xattr_header *header = NULL; 372 struct ext2_xattr_entry *here, *last; 373 size_t name_len, free, min_offs = sb->s_blocksize; 374 int not_found = 1, error; 375 char *end; 376 377 /* 378 * header -- Points either into bh, or to a temporarily 379 * allocated buffer. 380 * here -- The named entry found, or the place for inserting, within 381 * the block pointed to by header. 382 * last -- Points right after the last named entry within the block 383 * pointed to by header. 384 * min_offs -- The offset of the first value (values are aligned 385 * towards the end of the block). 386 * end -- Points right after the block pointed to by header. 387 */ 388 389 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld", 390 name_index, name, value, (long)value_len); 391 392 if (value == NULL) 393 value_len = 0; 394 if (name == NULL) 395 return -EINVAL; 396 name_len = strlen(name); 397 if (name_len > 255 || value_len > sb->s_blocksize) 398 return -ERANGE; 399 down_write(&EXT2_I(inode)->xattr_sem); 400 if (EXT2_I(inode)->i_file_acl) { 401 /* The inode already has an extended attribute block. */ 402 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl); 403 error = -EIO; 404 if (!bh) 405 goto cleanup; 406 ea_bdebug(bh, "b_count=%d, refcount=%d", 407 atomic_read(&(bh->b_count)), 408 le32_to_cpu(HDR(bh)->h_refcount)); 409 header = HDR(bh); 410 end = bh->b_data + bh->b_size; 411 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 412 header->h_blocks != cpu_to_le32(1)) { 413 bad_block: ext2_error(sb, "ext2_xattr_set", 414 "inode %ld: bad block %d", inode->i_ino, 415 EXT2_I(inode)->i_file_acl); 416 error = -EIO; 417 goto cleanup; 418 } 419 /* Find the named attribute. */ 420 here = FIRST_ENTRY(bh); 421 while (!IS_LAST_ENTRY(here)) { 422 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(here); 423 if ((char *)next >= end) 424 goto bad_block; 425 if (!here->e_value_block && here->e_value_size) { 426 size_t offs = le16_to_cpu(here->e_value_offs); 427 if (offs < min_offs) 428 min_offs = offs; 429 } 430 not_found = name_index - here->e_name_index; 431 if (!not_found) 432 not_found = name_len - here->e_name_len; 433 if (!not_found) 434 not_found = memcmp(name, here->e_name,name_len); 435 if (not_found <= 0) 436 break; 437 here = next; 438 } 439 last = here; 440 /* We still need to compute min_offs and last. */ 441 while (!IS_LAST_ENTRY(last)) { 442 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(last); 443 if ((char *)next >= end) 444 goto bad_block; 445 if (!last->e_value_block && last->e_value_size) { 446 size_t offs = le16_to_cpu(last->e_value_offs); 447 if (offs < min_offs) 448 min_offs = offs; 449 } 450 last = next; 451 } 452 453 /* Check whether we have enough space left. */ 454 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32); 455 } else { 456 /* We will use a new extended attribute block. */ 457 free = sb->s_blocksize - 458 sizeof(struct ext2_xattr_header) - sizeof(__u32); 459 here = last = NULL; /* avoid gcc uninitialized warning. */ 460 } 461 462 if (not_found) { 463 /* Request to remove a nonexistent attribute? */ 464 error = -ENODATA; 465 if (flags & XATTR_REPLACE) 466 goto cleanup; 467 error = 0; 468 if (value == NULL) 469 goto cleanup; 470 } else { 471 /* Request to create an existing attribute? */ 472 error = -EEXIST; 473 if (flags & XATTR_CREATE) 474 goto cleanup; 475 if (!here->e_value_block && here->e_value_size) { 476 size_t size = le32_to_cpu(here->e_value_size); 477 478 if (le16_to_cpu(here->e_value_offs) + size > 479 sb->s_blocksize || size > sb->s_blocksize) 480 goto bad_block; 481 free += EXT2_XATTR_SIZE(size); 482 } 483 free += EXT2_XATTR_LEN(name_len); 484 } 485 error = -ENOSPC; 486 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len)) 487 goto cleanup; 488 489 /* Here we know that we can set the new attribute. */ 490 491 if (header) { 492 struct mb_cache_entry *ce; 493 494 /* assert(header == HDR(bh)); */ 495 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, 496 bh->b_blocknr); 497 lock_buffer(bh); 498 if (header->h_refcount == cpu_to_le32(1)) { 499 ea_bdebug(bh, "modifying in-place"); 500 if (ce) 501 mb_cache_entry_free(ce); 502 /* keep the buffer locked while modifying it. */ 503 } else { 504 int offset; 505 506 if (ce) 507 mb_cache_entry_release(ce); 508 unlock_buffer(bh); 509 ea_bdebug(bh, "cloning"); 510 header = kmalloc(bh->b_size, GFP_KERNEL); 511 error = -ENOMEM; 512 if (header == NULL) 513 goto cleanup; 514 memcpy(header, HDR(bh), bh->b_size); 515 header->h_refcount = cpu_to_le32(1); 516 517 offset = (char *)here - bh->b_data; 518 here = ENTRY((char *)header + offset); 519 offset = (char *)last - bh->b_data; 520 last = ENTRY((char *)header + offset); 521 } 522 } else { 523 /* Allocate a buffer where we construct the new block. */ 524 header = kzalloc(sb->s_blocksize, GFP_KERNEL); 525 error = -ENOMEM; 526 if (header == NULL) 527 goto cleanup; 528 end = (char *)header + sb->s_blocksize; 529 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC); 530 header->h_blocks = header->h_refcount = cpu_to_le32(1); 531 last = here = ENTRY(header+1); 532 } 533 534 /* Iff we are modifying the block in-place, bh is locked here. */ 535 536 if (not_found) { 537 /* Insert the new name. */ 538 size_t size = EXT2_XATTR_LEN(name_len); 539 size_t rest = (char *)last - (char *)here; 540 memmove((char *)here + size, here, rest); 541 memset(here, 0, size); 542 here->e_name_index = name_index; 543 here->e_name_len = name_len; 544 memcpy(here->e_name, name, name_len); 545 } else { 546 if (!here->e_value_block && here->e_value_size) { 547 char *first_val = (char *)header + min_offs; 548 size_t offs = le16_to_cpu(here->e_value_offs); 549 char *val = (char *)header + offs; 550 size_t size = EXT2_XATTR_SIZE( 551 le32_to_cpu(here->e_value_size)); 552 553 if (size == EXT2_XATTR_SIZE(value_len)) { 554 /* The old and the new value have the same 555 size. Just replace. */ 556 here->e_value_size = cpu_to_le32(value_len); 557 memset(val + size - EXT2_XATTR_PAD, 0, 558 EXT2_XATTR_PAD); /* Clear pad bytes. */ 559 memcpy(val, value, value_len); 560 goto skip_replace; 561 } 562 563 /* Remove the old value. */ 564 memmove(first_val + size, first_val, val - first_val); 565 memset(first_val, 0, size); 566 here->e_value_offs = 0; 567 min_offs += size; 568 569 /* Adjust all value offsets. */ 570 last = ENTRY(header+1); 571 while (!IS_LAST_ENTRY(last)) { 572 size_t o = le16_to_cpu(last->e_value_offs); 573 if (!last->e_value_block && o < offs) 574 last->e_value_offs = 575 cpu_to_le16(o + size); 576 last = EXT2_XATTR_NEXT(last); 577 } 578 } 579 if (value == NULL) { 580 /* Remove the old name. */ 581 size_t size = EXT2_XATTR_LEN(name_len); 582 last = ENTRY((char *)last - size); 583 memmove(here, (char*)here + size, 584 (char*)last - (char*)here); 585 memset(last, 0, size); 586 } 587 } 588 589 if (value != NULL) { 590 /* Insert the new value. */ 591 here->e_value_size = cpu_to_le32(value_len); 592 if (value_len) { 593 size_t size = EXT2_XATTR_SIZE(value_len); 594 char *val = (char *)header + min_offs - size; 595 here->e_value_offs = 596 cpu_to_le16((char *)val - (char *)header); 597 memset(val + size - EXT2_XATTR_PAD, 0, 598 EXT2_XATTR_PAD); /* Clear the pad bytes. */ 599 memcpy(val, value, value_len); 600 } 601 } 602 603 skip_replace: 604 if (IS_LAST_ENTRY(ENTRY(header+1))) { 605 /* This block is now empty. */ 606 if (bh && header == HDR(bh)) 607 unlock_buffer(bh); /* we were modifying in-place. */ 608 error = ext2_xattr_set2(inode, bh, NULL); 609 } else { 610 ext2_xattr_rehash(header, here); 611 if (bh && header == HDR(bh)) 612 unlock_buffer(bh); /* we were modifying in-place. */ 613 error = ext2_xattr_set2(inode, bh, header); 614 } 615 616 cleanup: 617 brelse(bh); 618 if (!(bh && header == HDR(bh))) 619 kfree(header); 620 up_write(&EXT2_I(inode)->xattr_sem); 621 622 return error; 623 } 624 625 /* 626 * Second half of ext2_xattr_set(): Update the file system. 627 */ 628 static int 629 ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh, 630 struct ext2_xattr_header *header) 631 { 632 struct super_block *sb = inode->i_sb; 633 struct buffer_head *new_bh = NULL; 634 int error; 635 636 if (header) { 637 new_bh = ext2_xattr_cache_find(inode, header); 638 if (new_bh) { 639 /* We found an identical block in the cache. */ 640 if (new_bh == old_bh) { 641 ea_bdebug(new_bh, "keeping this block"); 642 } else { 643 /* The old block is released after updating 644 the inode. */ 645 ea_bdebug(new_bh, "reusing block"); 646 647 error = -EDQUOT; 648 if (DQUOT_ALLOC_BLOCK(inode, 1)) { 649 unlock_buffer(new_bh); 650 goto cleanup; 651 } 652 HDR(new_bh)->h_refcount = cpu_to_le32(1 + 653 le32_to_cpu(HDR(new_bh)->h_refcount)); 654 ea_bdebug(new_bh, "refcount now=%d", 655 le32_to_cpu(HDR(new_bh)->h_refcount)); 656 } 657 unlock_buffer(new_bh); 658 } else if (old_bh && header == HDR(old_bh)) { 659 /* Keep this block. No need to lock the block as we 660 don't need to change the reference count. */ 661 new_bh = old_bh; 662 get_bh(new_bh); 663 ext2_xattr_cache_insert(new_bh); 664 } else { 665 /* We need to allocate a new block */ 666 int goal = le32_to_cpu(EXT2_SB(sb)->s_es-> 667 s_first_data_block) + 668 EXT2_I(inode)->i_block_group * 669 EXT2_BLOCKS_PER_GROUP(sb); 670 int block = ext2_new_block(inode, goal, 671 NULL, NULL, &error); 672 if (error) 673 goto cleanup; 674 ea_idebug(inode, "creating block %d", block); 675 676 new_bh = sb_getblk(sb, block); 677 if (!new_bh) { 678 ext2_free_blocks(inode, block, 1); 679 error = -EIO; 680 goto cleanup; 681 } 682 lock_buffer(new_bh); 683 memcpy(new_bh->b_data, header, new_bh->b_size); 684 set_buffer_uptodate(new_bh); 685 unlock_buffer(new_bh); 686 ext2_xattr_cache_insert(new_bh); 687 688 ext2_xattr_update_super_block(sb); 689 } 690 mark_buffer_dirty(new_bh); 691 if (IS_SYNC(inode)) { 692 sync_dirty_buffer(new_bh); 693 error = -EIO; 694 if (buffer_req(new_bh) && !buffer_uptodate(new_bh)) 695 goto cleanup; 696 } 697 } 698 699 /* Update the inode. */ 700 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0; 701 inode->i_ctime = CURRENT_TIME_SEC; 702 if (IS_SYNC(inode)) { 703 error = ext2_sync_inode (inode); 704 /* In case sync failed due to ENOSPC the inode was actually 705 * written (only some dirty data were not) so we just proceed 706 * as if nothing happened and cleanup the unused block */ 707 if (error && error != -ENOSPC) { 708 if (new_bh && new_bh != old_bh) 709 DQUOT_FREE_BLOCK(inode, 1); 710 goto cleanup; 711 } 712 } else 713 mark_inode_dirty(inode); 714 715 error = 0; 716 if (old_bh && old_bh != new_bh) { 717 struct mb_cache_entry *ce; 718 719 /* 720 * If there was an old block and we are no longer using it, 721 * release the old block. 722 */ 723 ce = mb_cache_entry_get(ext2_xattr_cache, old_bh->b_bdev, 724 old_bh->b_blocknr); 725 lock_buffer(old_bh); 726 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) { 727 /* Free the old block. */ 728 if (ce) 729 mb_cache_entry_free(ce); 730 ea_bdebug(old_bh, "freeing"); 731 ext2_free_blocks(inode, old_bh->b_blocknr, 1); 732 /* We let our caller release old_bh, so we 733 * need to duplicate the buffer before. */ 734 get_bh(old_bh); 735 bforget(old_bh); 736 } else { 737 /* Decrement the refcount only. */ 738 HDR(old_bh)->h_refcount = cpu_to_le32( 739 le32_to_cpu(HDR(old_bh)->h_refcount) - 1); 740 if (ce) 741 mb_cache_entry_release(ce); 742 DQUOT_FREE_BLOCK(inode, 1); 743 mark_buffer_dirty(old_bh); 744 ea_bdebug(old_bh, "refcount now=%d", 745 le32_to_cpu(HDR(old_bh)->h_refcount)); 746 } 747 unlock_buffer(old_bh); 748 } 749 750 cleanup: 751 brelse(new_bh); 752 753 return error; 754 } 755 756 /* 757 * ext2_xattr_delete_inode() 758 * 759 * Free extended attribute resources associated with this inode. This 760 * is called immediately before an inode is freed. 761 */ 762 void 763 ext2_xattr_delete_inode(struct inode *inode) 764 { 765 struct buffer_head *bh = NULL; 766 struct mb_cache_entry *ce; 767 768 down_write(&EXT2_I(inode)->xattr_sem); 769 if (!EXT2_I(inode)->i_file_acl) 770 goto cleanup; 771 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 772 if (!bh) { 773 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 774 "inode %ld: block %d read error", inode->i_ino, 775 EXT2_I(inode)->i_file_acl); 776 goto cleanup; 777 } 778 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count))); 779 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 780 HDR(bh)->h_blocks != cpu_to_le32(1)) { 781 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 782 "inode %ld: bad block %d", inode->i_ino, 783 EXT2_I(inode)->i_file_acl); 784 goto cleanup; 785 } 786 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, bh->b_blocknr); 787 lock_buffer(bh); 788 if (HDR(bh)->h_refcount == cpu_to_le32(1)) { 789 if (ce) 790 mb_cache_entry_free(ce); 791 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1); 792 get_bh(bh); 793 bforget(bh); 794 unlock_buffer(bh); 795 } else { 796 HDR(bh)->h_refcount = cpu_to_le32( 797 le32_to_cpu(HDR(bh)->h_refcount) - 1); 798 if (ce) 799 mb_cache_entry_release(ce); 800 ea_bdebug(bh, "refcount now=%d", 801 le32_to_cpu(HDR(bh)->h_refcount)); 802 unlock_buffer(bh); 803 mark_buffer_dirty(bh); 804 if (IS_SYNC(inode)) 805 sync_dirty_buffer(bh); 806 DQUOT_FREE_BLOCK(inode, 1); 807 } 808 EXT2_I(inode)->i_file_acl = 0; 809 810 cleanup: 811 brelse(bh); 812 up_write(&EXT2_I(inode)->xattr_sem); 813 } 814 815 /* 816 * ext2_xattr_put_super() 817 * 818 * This is called when a file system is unmounted. 819 */ 820 void 821 ext2_xattr_put_super(struct super_block *sb) 822 { 823 mb_cache_shrink(sb->s_bdev); 824 } 825 826 827 /* 828 * ext2_xattr_cache_insert() 829 * 830 * Create a new entry in the extended attribute cache, and insert 831 * it unless such an entry is already in the cache. 832 * 833 * Returns 0, or a negative error number on failure. 834 */ 835 static int 836 ext2_xattr_cache_insert(struct buffer_head *bh) 837 { 838 __u32 hash = le32_to_cpu(HDR(bh)->h_hash); 839 struct mb_cache_entry *ce; 840 int error; 841 842 ce = mb_cache_entry_alloc(ext2_xattr_cache); 843 if (!ce) 844 return -ENOMEM; 845 error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash); 846 if (error) { 847 mb_cache_entry_free(ce); 848 if (error == -EBUSY) { 849 ea_bdebug(bh, "already in cache (%d cache entries)", 850 atomic_read(&ext2_xattr_cache->c_entry_count)); 851 error = 0; 852 } 853 } else { 854 ea_bdebug(bh, "inserting [%x] (%d cache entries)", (int)hash, 855 atomic_read(&ext2_xattr_cache->c_entry_count)); 856 mb_cache_entry_release(ce); 857 } 858 return error; 859 } 860 861 /* 862 * ext2_xattr_cmp() 863 * 864 * Compare two extended attribute blocks for equality. 865 * 866 * Returns 0 if the blocks are equal, 1 if they differ, and 867 * a negative error number on errors. 868 */ 869 static int 870 ext2_xattr_cmp(struct ext2_xattr_header *header1, 871 struct ext2_xattr_header *header2) 872 { 873 struct ext2_xattr_entry *entry1, *entry2; 874 875 entry1 = ENTRY(header1+1); 876 entry2 = ENTRY(header2+1); 877 while (!IS_LAST_ENTRY(entry1)) { 878 if (IS_LAST_ENTRY(entry2)) 879 return 1; 880 if (entry1->e_hash != entry2->e_hash || 881 entry1->e_name_index != entry2->e_name_index || 882 entry1->e_name_len != entry2->e_name_len || 883 entry1->e_value_size != entry2->e_value_size || 884 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len)) 885 return 1; 886 if (entry1->e_value_block != 0 || entry2->e_value_block != 0) 887 return -EIO; 888 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs), 889 (char *)header2 + le16_to_cpu(entry2->e_value_offs), 890 le32_to_cpu(entry1->e_value_size))) 891 return 1; 892 893 entry1 = EXT2_XATTR_NEXT(entry1); 894 entry2 = EXT2_XATTR_NEXT(entry2); 895 } 896 if (!IS_LAST_ENTRY(entry2)) 897 return 1; 898 return 0; 899 } 900 901 /* 902 * ext2_xattr_cache_find() 903 * 904 * Find an identical extended attribute block. 905 * 906 * Returns a locked buffer head to the block found, or NULL if such 907 * a block was not found or an error occurred. 908 */ 909 static struct buffer_head * 910 ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header) 911 { 912 __u32 hash = le32_to_cpu(header->h_hash); 913 struct mb_cache_entry *ce; 914 915 if (!header->h_hash) 916 return NULL; /* never share */ 917 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash); 918 again: 919 ce = mb_cache_entry_find_first(ext2_xattr_cache, 0, 920 inode->i_sb->s_bdev, hash); 921 while (ce) { 922 struct buffer_head *bh; 923 924 if (IS_ERR(ce)) { 925 if (PTR_ERR(ce) == -EAGAIN) 926 goto again; 927 break; 928 } 929 930 bh = sb_bread(inode->i_sb, ce->e_block); 931 if (!bh) { 932 ext2_error(inode->i_sb, "ext2_xattr_cache_find", 933 "inode %ld: block %ld read error", 934 inode->i_ino, (unsigned long) ce->e_block); 935 } else { 936 lock_buffer(bh); 937 if (le32_to_cpu(HDR(bh)->h_refcount) > 938 EXT2_XATTR_REFCOUNT_MAX) { 939 ea_idebug(inode, "block %ld refcount %d>%d", 940 (unsigned long) ce->e_block, 941 le32_to_cpu(HDR(bh)->h_refcount), 942 EXT2_XATTR_REFCOUNT_MAX); 943 } else if (!ext2_xattr_cmp(header, HDR(bh))) { 944 ea_bdebug(bh, "b_count=%d", 945 atomic_read(&(bh->b_count))); 946 mb_cache_entry_release(ce); 947 return bh; 948 } 949 unlock_buffer(bh); 950 brelse(bh); 951 } 952 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash); 953 } 954 return NULL; 955 } 956 957 #define NAME_HASH_SHIFT 5 958 #define VALUE_HASH_SHIFT 16 959 960 /* 961 * ext2_xattr_hash_entry() 962 * 963 * Compute the hash of an extended attribute. 964 */ 965 static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header, 966 struct ext2_xattr_entry *entry) 967 { 968 __u32 hash = 0; 969 char *name = entry->e_name; 970 int n; 971 972 for (n=0; n < entry->e_name_len; n++) { 973 hash = (hash << NAME_HASH_SHIFT) ^ 974 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^ 975 *name++; 976 } 977 978 if (entry->e_value_block == 0 && entry->e_value_size != 0) { 979 __le32 *value = (__le32 *)((char *)header + 980 le16_to_cpu(entry->e_value_offs)); 981 for (n = (le32_to_cpu(entry->e_value_size) + 982 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) { 983 hash = (hash << VALUE_HASH_SHIFT) ^ 984 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^ 985 le32_to_cpu(*value++); 986 } 987 } 988 entry->e_hash = cpu_to_le32(hash); 989 } 990 991 #undef NAME_HASH_SHIFT 992 #undef VALUE_HASH_SHIFT 993 994 #define BLOCK_HASH_SHIFT 16 995 996 /* 997 * ext2_xattr_rehash() 998 * 999 * Re-compute the extended attribute hash value after an entry has changed. 1000 */ 1001 static void ext2_xattr_rehash(struct ext2_xattr_header *header, 1002 struct ext2_xattr_entry *entry) 1003 { 1004 struct ext2_xattr_entry *here; 1005 __u32 hash = 0; 1006 1007 ext2_xattr_hash_entry(header, entry); 1008 here = ENTRY(header+1); 1009 while (!IS_LAST_ENTRY(here)) { 1010 if (!here->e_hash) { 1011 /* Block is not shared if an entry's hash value == 0 */ 1012 hash = 0; 1013 break; 1014 } 1015 hash = (hash << BLOCK_HASH_SHIFT) ^ 1016 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^ 1017 le32_to_cpu(here->e_hash); 1018 here = EXT2_XATTR_NEXT(here); 1019 } 1020 header->h_hash = cpu_to_le32(hash); 1021 } 1022 1023 #undef BLOCK_HASH_SHIFT 1024 1025 int __init 1026 init_ext2_xattr(void) 1027 { 1028 ext2_xattr_cache = mb_cache_create("ext2_xattr", NULL, 1029 sizeof(struct mb_cache_entry) + 1030 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6); 1031 if (!ext2_xattr_cache) 1032 return -ENOMEM; 1033 return 0; 1034 } 1035 1036 void 1037 exit_ext2_xattr(void) 1038 { 1039 mb_cache_destroy(ext2_xattr_cache); 1040 } 1041