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_sem: 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 (IS_RDONLY(inode)) 393 return -EROFS; 394 if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) 395 return -EPERM; 396 if (value == NULL) 397 value_len = 0; 398 if (name == NULL) 399 return -EINVAL; 400 name_len = strlen(name); 401 if (name_len > 255 || value_len > sb->s_blocksize) 402 return -ERANGE; 403 down_write(&EXT2_I(inode)->xattr_sem); 404 if (EXT2_I(inode)->i_file_acl) { 405 /* The inode already has an extended attribute block. */ 406 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl); 407 error = -EIO; 408 if (!bh) 409 goto cleanup; 410 ea_bdebug(bh, "b_count=%d, refcount=%d", 411 atomic_read(&(bh->b_count)), 412 le32_to_cpu(HDR(bh)->h_refcount)); 413 header = HDR(bh); 414 end = bh->b_data + bh->b_size; 415 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 416 header->h_blocks != cpu_to_le32(1)) { 417 bad_block: ext2_error(sb, "ext2_xattr_set", 418 "inode %ld: bad block %d", inode->i_ino, 419 EXT2_I(inode)->i_file_acl); 420 error = -EIO; 421 goto cleanup; 422 } 423 /* Find the named attribute. */ 424 here = FIRST_ENTRY(bh); 425 while (!IS_LAST_ENTRY(here)) { 426 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(here); 427 if ((char *)next >= end) 428 goto bad_block; 429 if (!here->e_value_block && here->e_value_size) { 430 size_t offs = le16_to_cpu(here->e_value_offs); 431 if (offs < min_offs) 432 min_offs = offs; 433 } 434 not_found = name_index - here->e_name_index; 435 if (!not_found) 436 not_found = name_len - here->e_name_len; 437 if (!not_found) 438 not_found = memcmp(name, here->e_name,name_len); 439 if (not_found <= 0) 440 break; 441 here = next; 442 } 443 last = here; 444 /* We still need to compute min_offs and last. */ 445 while (!IS_LAST_ENTRY(last)) { 446 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(last); 447 if ((char *)next >= end) 448 goto bad_block; 449 if (!last->e_value_block && last->e_value_size) { 450 size_t offs = le16_to_cpu(last->e_value_offs); 451 if (offs < min_offs) 452 min_offs = offs; 453 } 454 last = next; 455 } 456 457 /* Check whether we have enough space left. */ 458 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32); 459 } else { 460 /* We will use a new extended attribute block. */ 461 free = sb->s_blocksize - 462 sizeof(struct ext2_xattr_header) - sizeof(__u32); 463 here = last = NULL; /* avoid gcc uninitialized warning. */ 464 } 465 466 if (not_found) { 467 /* Request to remove a nonexistent attribute? */ 468 error = -ENODATA; 469 if (flags & XATTR_REPLACE) 470 goto cleanup; 471 error = 0; 472 if (value == NULL) 473 goto cleanup; 474 } else { 475 /* Request to create an existing attribute? */ 476 error = -EEXIST; 477 if (flags & XATTR_CREATE) 478 goto cleanup; 479 if (!here->e_value_block && here->e_value_size) { 480 size_t size = le32_to_cpu(here->e_value_size); 481 482 if (le16_to_cpu(here->e_value_offs) + size > 483 sb->s_blocksize || size > sb->s_blocksize) 484 goto bad_block; 485 free += EXT2_XATTR_SIZE(size); 486 } 487 free += EXT2_XATTR_LEN(name_len); 488 } 489 error = -ENOSPC; 490 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len)) 491 goto cleanup; 492 493 /* Here we know that we can set the new attribute. */ 494 495 if (header) { 496 struct mb_cache_entry *ce; 497 498 /* assert(header == HDR(bh)); */ 499 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, 500 bh->b_blocknr); 501 lock_buffer(bh); 502 if (header->h_refcount == cpu_to_le32(1)) { 503 ea_bdebug(bh, "modifying in-place"); 504 if (ce) 505 mb_cache_entry_free(ce); 506 /* keep the buffer locked while modifying it. */ 507 } else { 508 int offset; 509 510 if (ce) 511 mb_cache_entry_release(ce); 512 unlock_buffer(bh); 513 ea_bdebug(bh, "cloning"); 514 header = kmalloc(bh->b_size, GFP_KERNEL); 515 error = -ENOMEM; 516 if (header == NULL) 517 goto cleanup; 518 memcpy(header, HDR(bh), bh->b_size); 519 header->h_refcount = cpu_to_le32(1); 520 521 offset = (char *)here - bh->b_data; 522 here = ENTRY((char *)header + offset); 523 offset = (char *)last - bh->b_data; 524 last = ENTRY((char *)header + offset); 525 } 526 } else { 527 /* Allocate a buffer where we construct the new block. */ 528 header = kmalloc(sb->s_blocksize, GFP_KERNEL); 529 error = -ENOMEM; 530 if (header == NULL) 531 goto cleanup; 532 memset(header, 0, sb->s_blocksize); 533 end = (char *)header + sb->s_blocksize; 534 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC); 535 header->h_blocks = header->h_refcount = cpu_to_le32(1); 536 last = here = ENTRY(header+1); 537 } 538 539 /* Iff we are modifying the block in-place, bh is locked here. */ 540 541 if (not_found) { 542 /* Insert the new name. */ 543 size_t size = EXT2_XATTR_LEN(name_len); 544 size_t rest = (char *)last - (char *)here; 545 memmove((char *)here + size, here, rest); 546 memset(here, 0, size); 547 here->e_name_index = name_index; 548 here->e_name_len = name_len; 549 memcpy(here->e_name, name, name_len); 550 } else { 551 if (!here->e_value_block && here->e_value_size) { 552 char *first_val = (char *)header + min_offs; 553 size_t offs = le16_to_cpu(here->e_value_offs); 554 char *val = (char *)header + offs; 555 size_t size = EXT2_XATTR_SIZE( 556 le32_to_cpu(here->e_value_size)); 557 558 if (size == EXT2_XATTR_SIZE(value_len)) { 559 /* The old and the new value have the same 560 size. Just replace. */ 561 here->e_value_size = cpu_to_le32(value_len); 562 memset(val + size - EXT2_XATTR_PAD, 0, 563 EXT2_XATTR_PAD); /* Clear pad bytes. */ 564 memcpy(val, value, value_len); 565 goto skip_replace; 566 } 567 568 /* Remove the old value. */ 569 memmove(first_val + size, first_val, val - first_val); 570 memset(first_val, 0, size); 571 here->e_value_offs = 0; 572 min_offs += size; 573 574 /* Adjust all value offsets. */ 575 last = ENTRY(header+1); 576 while (!IS_LAST_ENTRY(last)) { 577 size_t o = le16_to_cpu(last->e_value_offs); 578 if (!last->e_value_block && o < offs) 579 last->e_value_offs = 580 cpu_to_le16(o + size); 581 last = EXT2_XATTR_NEXT(last); 582 } 583 } 584 if (value == NULL) { 585 /* Remove the old name. */ 586 size_t size = EXT2_XATTR_LEN(name_len); 587 last = ENTRY((char *)last - size); 588 memmove(here, (char*)here + size, 589 (char*)last - (char*)here); 590 memset(last, 0, size); 591 } 592 } 593 594 if (value != NULL) { 595 /* Insert the new value. */ 596 here->e_value_size = cpu_to_le32(value_len); 597 if (value_len) { 598 size_t size = EXT2_XATTR_SIZE(value_len); 599 char *val = (char *)header + min_offs - size; 600 here->e_value_offs = 601 cpu_to_le16((char *)val - (char *)header); 602 memset(val + size - EXT2_XATTR_PAD, 0, 603 EXT2_XATTR_PAD); /* Clear the pad bytes. */ 604 memcpy(val, value, value_len); 605 } 606 } 607 608 skip_replace: 609 if (IS_LAST_ENTRY(ENTRY(header+1))) { 610 /* This block is now empty. */ 611 if (bh && header == HDR(bh)) 612 unlock_buffer(bh); /* we were modifying in-place. */ 613 error = ext2_xattr_set2(inode, bh, NULL); 614 } else { 615 ext2_xattr_rehash(header, here); 616 if (bh && header == HDR(bh)) 617 unlock_buffer(bh); /* we were modifying in-place. */ 618 error = ext2_xattr_set2(inode, bh, header); 619 } 620 621 cleanup: 622 brelse(bh); 623 if (!(bh && header == HDR(bh))) 624 kfree(header); 625 up_write(&EXT2_I(inode)->xattr_sem); 626 627 return error; 628 } 629 630 /* 631 * Second half of ext2_xattr_set(): Update the file system. 632 */ 633 static int 634 ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh, 635 struct ext2_xattr_header *header) 636 { 637 struct super_block *sb = inode->i_sb; 638 struct buffer_head *new_bh = NULL; 639 int error; 640 641 if (header) { 642 new_bh = ext2_xattr_cache_find(inode, header); 643 if (new_bh) { 644 /* We found an identical block in the cache. */ 645 if (new_bh == old_bh) { 646 ea_bdebug(new_bh, "keeping this block"); 647 } else { 648 /* The old block is released after updating 649 the inode. */ 650 ea_bdebug(new_bh, "reusing block"); 651 652 error = -EDQUOT; 653 if (DQUOT_ALLOC_BLOCK(inode, 1)) { 654 unlock_buffer(new_bh); 655 goto cleanup; 656 } 657 HDR(new_bh)->h_refcount = cpu_to_le32(1 + 658 le32_to_cpu(HDR(new_bh)->h_refcount)); 659 ea_bdebug(new_bh, "refcount now=%d", 660 le32_to_cpu(HDR(new_bh)->h_refcount)); 661 } 662 unlock_buffer(new_bh); 663 } else if (old_bh && header == HDR(old_bh)) { 664 /* Keep this block. No need to lock the block as we 665 don't need to change the reference count. */ 666 new_bh = old_bh; 667 get_bh(new_bh); 668 ext2_xattr_cache_insert(new_bh); 669 } else { 670 /* We need to allocate a new block */ 671 int goal = le32_to_cpu(EXT2_SB(sb)->s_es-> 672 s_first_data_block) + 673 EXT2_I(inode)->i_block_group * 674 EXT2_BLOCKS_PER_GROUP(sb); 675 int block = ext2_new_block(inode, goal, 676 NULL, NULL, &error); 677 if (error) 678 goto cleanup; 679 ea_idebug(inode, "creating block %d", block); 680 681 new_bh = sb_getblk(sb, block); 682 if (!new_bh) { 683 ext2_free_blocks(inode, block, 1); 684 error = -EIO; 685 goto cleanup; 686 } 687 lock_buffer(new_bh); 688 memcpy(new_bh->b_data, header, new_bh->b_size); 689 set_buffer_uptodate(new_bh); 690 unlock_buffer(new_bh); 691 ext2_xattr_cache_insert(new_bh); 692 693 ext2_xattr_update_super_block(sb); 694 } 695 mark_buffer_dirty(new_bh); 696 if (IS_SYNC(inode)) { 697 sync_dirty_buffer(new_bh); 698 error = -EIO; 699 if (buffer_req(new_bh) && !buffer_uptodate(new_bh)) 700 goto cleanup; 701 } 702 } 703 704 /* Update the inode. */ 705 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0; 706 inode->i_ctime = CURRENT_TIME_SEC; 707 if (IS_SYNC(inode)) { 708 error = ext2_sync_inode (inode); 709 /* In case sync failed due to ENOSPC the inode was actually 710 * written (only some dirty data were not) so we just proceed 711 * as if nothing happened and cleanup the unused block */ 712 if (error && error != -ENOSPC) { 713 if (new_bh && new_bh != old_bh) 714 DQUOT_FREE_BLOCK(inode, 1); 715 goto cleanup; 716 } 717 } else 718 mark_inode_dirty(inode); 719 720 error = 0; 721 if (old_bh && old_bh != new_bh) { 722 struct mb_cache_entry *ce; 723 724 /* 725 * If there was an old block and we are no longer using it, 726 * release the old block. 727 */ 728 ce = mb_cache_entry_get(ext2_xattr_cache, old_bh->b_bdev, 729 old_bh->b_blocknr); 730 lock_buffer(old_bh); 731 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) { 732 /* Free the old block. */ 733 if (ce) 734 mb_cache_entry_free(ce); 735 ea_bdebug(old_bh, "freeing"); 736 ext2_free_blocks(inode, old_bh->b_blocknr, 1); 737 /* We let our caller release old_bh, so we 738 * need to duplicate the buffer before. */ 739 get_bh(old_bh); 740 bforget(old_bh); 741 } else { 742 /* Decrement the refcount only. */ 743 HDR(old_bh)->h_refcount = cpu_to_le32( 744 le32_to_cpu(HDR(old_bh)->h_refcount) - 1); 745 if (ce) 746 mb_cache_entry_release(ce); 747 DQUOT_FREE_BLOCK(inode, 1); 748 mark_buffer_dirty(old_bh); 749 ea_bdebug(old_bh, "refcount now=%d", 750 le32_to_cpu(HDR(old_bh)->h_refcount)); 751 } 752 unlock_buffer(old_bh); 753 } 754 755 cleanup: 756 brelse(new_bh); 757 758 return error; 759 } 760 761 /* 762 * ext2_xattr_delete_inode() 763 * 764 * Free extended attribute resources associated with this inode. This 765 * is called immediately before an inode is freed. 766 */ 767 void 768 ext2_xattr_delete_inode(struct inode *inode) 769 { 770 struct buffer_head *bh = NULL; 771 struct mb_cache_entry *ce; 772 773 down_write(&EXT2_I(inode)->xattr_sem); 774 if (!EXT2_I(inode)->i_file_acl) 775 goto cleanup; 776 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 777 if (!bh) { 778 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 779 "inode %ld: block %d read error", inode->i_ino, 780 EXT2_I(inode)->i_file_acl); 781 goto cleanup; 782 } 783 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count))); 784 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 785 HDR(bh)->h_blocks != cpu_to_le32(1)) { 786 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 787 "inode %ld: bad block %d", inode->i_ino, 788 EXT2_I(inode)->i_file_acl); 789 goto cleanup; 790 } 791 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, bh->b_blocknr); 792 lock_buffer(bh); 793 if (HDR(bh)->h_refcount == cpu_to_le32(1)) { 794 if (ce) 795 mb_cache_entry_free(ce); 796 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1); 797 get_bh(bh); 798 bforget(bh); 799 } else { 800 HDR(bh)->h_refcount = cpu_to_le32( 801 le32_to_cpu(HDR(bh)->h_refcount) - 1); 802 if (ce) 803 mb_cache_entry_release(ce); 804 mark_buffer_dirty(bh); 805 if (IS_SYNC(inode)) 806 sync_dirty_buffer(bh); 807 DQUOT_FREE_BLOCK(inode, 1); 808 } 809 ea_bdebug(bh, "refcount now=%d", le32_to_cpu(HDR(bh)->h_refcount) - 1); 810 unlock_buffer(bh); 811 EXT2_I(inode)->i_file_acl = 0; 812 813 cleanup: 814 brelse(bh); 815 up_write(&EXT2_I(inode)->xattr_sem); 816 } 817 818 /* 819 * ext2_xattr_put_super() 820 * 821 * This is called when a file system is unmounted. 822 */ 823 void 824 ext2_xattr_put_super(struct super_block *sb) 825 { 826 mb_cache_shrink(sb->s_bdev); 827 } 828 829 830 /* 831 * ext2_xattr_cache_insert() 832 * 833 * Create a new entry in the extended attribute cache, and insert 834 * it unless such an entry is already in the cache. 835 * 836 * Returns 0, or a negative error number on failure. 837 */ 838 static int 839 ext2_xattr_cache_insert(struct buffer_head *bh) 840 { 841 __u32 hash = le32_to_cpu(HDR(bh)->h_hash); 842 struct mb_cache_entry *ce; 843 int error; 844 845 ce = mb_cache_entry_alloc(ext2_xattr_cache); 846 if (!ce) 847 return -ENOMEM; 848 error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash); 849 if (error) { 850 mb_cache_entry_free(ce); 851 if (error == -EBUSY) { 852 ea_bdebug(bh, "already in cache (%d cache entries)", 853 atomic_read(&ext2_xattr_cache->c_entry_count)); 854 error = 0; 855 } 856 } else { 857 ea_bdebug(bh, "inserting [%x] (%d cache entries)", (int)hash, 858 atomic_read(&ext2_xattr_cache->c_entry_count)); 859 mb_cache_entry_release(ce); 860 } 861 return error; 862 } 863 864 /* 865 * ext2_xattr_cmp() 866 * 867 * Compare two extended attribute blocks for equality. 868 * 869 * Returns 0 if the blocks are equal, 1 if they differ, and 870 * a negative error number on errors. 871 */ 872 static int 873 ext2_xattr_cmp(struct ext2_xattr_header *header1, 874 struct ext2_xattr_header *header2) 875 { 876 struct ext2_xattr_entry *entry1, *entry2; 877 878 entry1 = ENTRY(header1+1); 879 entry2 = ENTRY(header2+1); 880 while (!IS_LAST_ENTRY(entry1)) { 881 if (IS_LAST_ENTRY(entry2)) 882 return 1; 883 if (entry1->e_hash != entry2->e_hash || 884 entry1->e_name_index != entry2->e_name_index || 885 entry1->e_name_len != entry2->e_name_len || 886 entry1->e_value_size != entry2->e_value_size || 887 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len)) 888 return 1; 889 if (entry1->e_value_block != 0 || entry2->e_value_block != 0) 890 return -EIO; 891 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs), 892 (char *)header2 + le16_to_cpu(entry2->e_value_offs), 893 le32_to_cpu(entry1->e_value_size))) 894 return 1; 895 896 entry1 = EXT2_XATTR_NEXT(entry1); 897 entry2 = EXT2_XATTR_NEXT(entry2); 898 } 899 if (!IS_LAST_ENTRY(entry2)) 900 return 1; 901 return 0; 902 } 903 904 /* 905 * ext2_xattr_cache_find() 906 * 907 * Find an identical extended attribute block. 908 * 909 * Returns a locked buffer head to the block found, or NULL if such 910 * a block was not found or an error occurred. 911 */ 912 static struct buffer_head * 913 ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header) 914 { 915 __u32 hash = le32_to_cpu(header->h_hash); 916 struct mb_cache_entry *ce; 917 918 if (!header->h_hash) 919 return NULL; /* never share */ 920 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash); 921 again: 922 ce = mb_cache_entry_find_first(ext2_xattr_cache, 0, 923 inode->i_sb->s_bdev, hash); 924 while (ce) { 925 struct buffer_head *bh; 926 927 if (IS_ERR(ce)) { 928 if (PTR_ERR(ce) == -EAGAIN) 929 goto again; 930 break; 931 } 932 933 bh = sb_bread(inode->i_sb, ce->e_block); 934 if (!bh) { 935 ext2_error(inode->i_sb, "ext2_xattr_cache_find", 936 "inode %ld: block %ld read error", 937 inode->i_ino, (unsigned long) ce->e_block); 938 } else { 939 lock_buffer(bh); 940 if (le32_to_cpu(HDR(bh)->h_refcount) > 941 EXT2_XATTR_REFCOUNT_MAX) { 942 ea_idebug(inode, "block %ld refcount %d>%d", 943 (unsigned long) ce->e_block, 944 le32_to_cpu(HDR(bh)->h_refcount), 945 EXT2_XATTR_REFCOUNT_MAX); 946 } else if (!ext2_xattr_cmp(header, HDR(bh))) { 947 ea_bdebug(bh, "b_count=%d", 948 atomic_read(&(bh->b_count))); 949 mb_cache_entry_release(ce); 950 return bh; 951 } 952 unlock_buffer(bh); 953 brelse(bh); 954 } 955 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash); 956 } 957 return NULL; 958 } 959 960 #define NAME_HASH_SHIFT 5 961 #define VALUE_HASH_SHIFT 16 962 963 /* 964 * ext2_xattr_hash_entry() 965 * 966 * Compute the hash of an extended attribute. 967 */ 968 static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header, 969 struct ext2_xattr_entry *entry) 970 { 971 __u32 hash = 0; 972 char *name = entry->e_name; 973 int n; 974 975 for (n=0; n < entry->e_name_len; n++) { 976 hash = (hash << NAME_HASH_SHIFT) ^ 977 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^ 978 *name++; 979 } 980 981 if (entry->e_value_block == 0 && entry->e_value_size != 0) { 982 __le32 *value = (__le32 *)((char *)header + 983 le16_to_cpu(entry->e_value_offs)); 984 for (n = (le32_to_cpu(entry->e_value_size) + 985 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) { 986 hash = (hash << VALUE_HASH_SHIFT) ^ 987 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^ 988 le32_to_cpu(*value++); 989 } 990 } 991 entry->e_hash = cpu_to_le32(hash); 992 } 993 994 #undef NAME_HASH_SHIFT 995 #undef VALUE_HASH_SHIFT 996 997 #define BLOCK_HASH_SHIFT 16 998 999 /* 1000 * ext2_xattr_rehash() 1001 * 1002 * Re-compute the extended attribute hash value after an entry has changed. 1003 */ 1004 static void ext2_xattr_rehash(struct ext2_xattr_header *header, 1005 struct ext2_xattr_entry *entry) 1006 { 1007 struct ext2_xattr_entry *here; 1008 __u32 hash = 0; 1009 1010 ext2_xattr_hash_entry(header, entry); 1011 here = ENTRY(header+1); 1012 while (!IS_LAST_ENTRY(here)) { 1013 if (!here->e_hash) { 1014 /* Block is not shared if an entry's hash value == 0 */ 1015 hash = 0; 1016 break; 1017 } 1018 hash = (hash << BLOCK_HASH_SHIFT) ^ 1019 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^ 1020 le32_to_cpu(here->e_hash); 1021 here = EXT2_XATTR_NEXT(here); 1022 } 1023 header->h_hash = cpu_to_le32(hash); 1024 } 1025 1026 #undef BLOCK_HASH_SHIFT 1027 1028 int __init 1029 init_ext2_xattr(void) 1030 { 1031 ext2_xattr_cache = mb_cache_create("ext2_xattr", NULL, 1032 sizeof(struct mb_cache_entry) + 1033 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6); 1034 if (!ext2_xattr_cache) 1035 return -ENOMEM; 1036 return 0; 1037 } 1038 1039 void 1040 exit_ext2_xattr(void) 1041 { 1042 mb_cache_destroy(ext2_xattr_cache); 1043 } 1044