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 aligned 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/init.h> 58 #include <linux/slab.h> 59 #include <linux/mbcache.h> 60 #include <linux/quotaops.h> 61 #include <linux/rwsem.h> 62 #include <linux/security.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 const 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 const 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 const struct xattr_handler * 129 ext2_xattr_handler(int name_index) 130 { 131 const 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 name_len = strlen(name); 164 if (name_len > 255) 165 return -ERANGE; 166 167 down_read(&EXT2_I(inode)->xattr_sem); 168 error = -ENODATA; 169 if (!EXT2_I(inode)->i_file_acl) 170 goto cleanup; 171 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); 172 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 173 error = -EIO; 174 if (!bh) 175 goto cleanup; 176 ea_bdebug(bh, "b_count=%d, refcount=%d", 177 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount)); 178 end = bh->b_data + bh->b_size; 179 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 180 HDR(bh)->h_blocks != cpu_to_le32(1)) { 181 bad_block: ext2_error(inode->i_sb, "ext2_xattr_get", 182 "inode %ld: bad block %d", inode->i_ino, 183 EXT2_I(inode)->i_file_acl); 184 error = -EIO; 185 goto cleanup; 186 } 187 188 /* find named attribute */ 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 if (ext2_xattr_cache_insert(bh)) 202 ea_idebug(inode, "cache insert failed"); 203 error = -ENODATA; 204 goto cleanup; 205 found: 206 /* check the buffer size */ 207 if (entry->e_value_block != 0) 208 goto bad_block; 209 size = le32_to_cpu(entry->e_value_size); 210 if (size > inode->i_sb->s_blocksize || 211 le16_to_cpu(entry->e_value_offs) + size > inode->i_sb->s_blocksize) 212 goto bad_block; 213 214 if (ext2_xattr_cache_insert(bh)) 215 ea_idebug(inode, "cache insert failed"); 216 if (buffer) { 217 error = -ERANGE; 218 if (size > buffer_size) 219 goto cleanup; 220 /* return value of attribute */ 221 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs), 222 size); 223 } 224 error = size; 225 226 cleanup: 227 brelse(bh); 228 up_read(&EXT2_I(inode)->xattr_sem); 229 230 return error; 231 } 232 233 /* 234 * ext2_xattr_list() 235 * 236 * Copy a list of attribute names into the buffer 237 * provided, or compute the buffer size required. 238 * Buffer is NULL to compute the size of the buffer required. 239 * 240 * Returns a negative error number on failure, or the number of bytes 241 * used / required on success. 242 */ 243 static int 244 ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size) 245 { 246 struct inode *inode = dentry->d_inode; 247 struct buffer_head *bh = NULL; 248 struct ext2_xattr_entry *entry; 249 char *end; 250 size_t rest = buffer_size; 251 int error; 252 253 ea_idebug(inode, "buffer=%p, buffer_size=%ld", 254 buffer, (long)buffer_size); 255 256 down_read(&EXT2_I(inode)->xattr_sem); 257 error = 0; 258 if (!EXT2_I(inode)->i_file_acl) 259 goto cleanup; 260 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); 261 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 262 error = -EIO; 263 if (!bh) 264 goto cleanup; 265 ea_bdebug(bh, "b_count=%d, refcount=%d", 266 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount)); 267 end = bh->b_data + bh->b_size; 268 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 269 HDR(bh)->h_blocks != cpu_to_le32(1)) { 270 bad_block: ext2_error(inode->i_sb, "ext2_xattr_list", 271 "inode %ld: bad block %d", inode->i_ino, 272 EXT2_I(inode)->i_file_acl); 273 error = -EIO; 274 goto cleanup; 275 } 276 277 /* check the on-disk data structure */ 278 entry = FIRST_ENTRY(bh); 279 while (!IS_LAST_ENTRY(entry)) { 280 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(entry); 281 282 if ((char *)next >= end) 283 goto bad_block; 284 entry = next; 285 } 286 if (ext2_xattr_cache_insert(bh)) 287 ea_idebug(inode, "cache insert failed"); 288 289 /* list the attribute names */ 290 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry); 291 entry = EXT2_XATTR_NEXT(entry)) { 292 const struct xattr_handler *handler = 293 ext2_xattr_handler(entry->e_name_index); 294 295 if (handler) { 296 size_t size = handler->list(dentry, buffer, rest, 297 entry->e_name, 298 entry->e_name_len, 299 handler->flags); 300 if (buffer) { 301 if (size > rest) { 302 error = -ERANGE; 303 goto cleanup; 304 } 305 buffer += size; 306 } 307 rest -= size; 308 } 309 } 310 error = buffer_size - rest; /* total size */ 311 312 cleanup: 313 brelse(bh); 314 up_read(&EXT2_I(inode)->xattr_sem); 315 316 return error; 317 } 318 319 /* 320 * Inode operation listxattr() 321 * 322 * dentry->d_inode->i_mutex: don't care 323 */ 324 ssize_t 325 ext2_listxattr(struct dentry *dentry, char *buffer, size_t size) 326 { 327 return ext2_xattr_list(dentry, buffer, size); 328 } 329 330 /* 331 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is 332 * not set, set it. 333 */ 334 static void ext2_xattr_update_super_block(struct super_block *sb) 335 { 336 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR)) 337 return; 338 339 spin_lock(&EXT2_SB(sb)->s_lock); 340 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR); 341 spin_unlock(&EXT2_SB(sb)->s_lock); 342 mark_buffer_dirty(EXT2_SB(sb)->s_sbh); 343 } 344 345 /* 346 * ext2_xattr_set() 347 * 348 * Create, replace or remove an extended attribute for this inode. Value 349 * is NULL to remove an existing extended attribute, and non-NULL to 350 * either replace an existing extended attribute, or create a new extended 351 * attribute. The flags XATTR_REPLACE and XATTR_CREATE 352 * specify that an extended attribute must exist and must not exist 353 * previous to the call, respectively. 354 * 355 * Returns 0, or a negative error number on failure. 356 */ 357 int 358 ext2_xattr_set(struct inode *inode, int name_index, const char *name, 359 const void *value, size_t value_len, int flags) 360 { 361 struct super_block *sb = inode->i_sb; 362 struct buffer_head *bh = NULL; 363 struct ext2_xattr_header *header = NULL; 364 struct ext2_xattr_entry *here, *last; 365 size_t name_len, free, min_offs = sb->s_blocksize; 366 int not_found = 1, error; 367 char *end; 368 369 /* 370 * header -- Points either into bh, or to a temporarily 371 * allocated buffer. 372 * here -- The named entry found, or the place for inserting, within 373 * the block pointed to by header. 374 * last -- Points right after the last named entry within the block 375 * pointed to by header. 376 * min_offs -- The offset of the first value (values are aligned 377 * towards the end of the block). 378 * end -- Points right after the block pointed to by header. 379 */ 380 381 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld", 382 name_index, name, value, (long)value_len); 383 384 if (value == NULL) 385 value_len = 0; 386 if (name == NULL) 387 return -EINVAL; 388 name_len = strlen(name); 389 if (name_len > 255 || value_len > sb->s_blocksize) 390 return -ERANGE; 391 down_write(&EXT2_I(inode)->xattr_sem); 392 if (EXT2_I(inode)->i_file_acl) { 393 /* The inode already has an extended attribute block. */ 394 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl); 395 error = -EIO; 396 if (!bh) 397 goto cleanup; 398 ea_bdebug(bh, "b_count=%d, refcount=%d", 399 atomic_read(&(bh->b_count)), 400 le32_to_cpu(HDR(bh)->h_refcount)); 401 header = HDR(bh); 402 end = bh->b_data + bh->b_size; 403 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 404 header->h_blocks != cpu_to_le32(1)) { 405 bad_block: ext2_error(sb, "ext2_xattr_set", 406 "inode %ld: bad block %d", inode->i_ino, 407 EXT2_I(inode)->i_file_acl); 408 error = -EIO; 409 goto cleanup; 410 } 411 /* Find the named attribute. */ 412 here = FIRST_ENTRY(bh); 413 while (!IS_LAST_ENTRY(here)) { 414 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(here); 415 if ((char *)next >= end) 416 goto bad_block; 417 if (!here->e_value_block && here->e_value_size) { 418 size_t offs = le16_to_cpu(here->e_value_offs); 419 if (offs < min_offs) 420 min_offs = offs; 421 } 422 not_found = name_index - here->e_name_index; 423 if (!not_found) 424 not_found = name_len - here->e_name_len; 425 if (!not_found) 426 not_found = memcmp(name, here->e_name,name_len); 427 if (not_found <= 0) 428 break; 429 here = next; 430 } 431 last = here; 432 /* We still need to compute min_offs and last. */ 433 while (!IS_LAST_ENTRY(last)) { 434 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(last); 435 if ((char *)next >= end) 436 goto bad_block; 437 if (!last->e_value_block && last->e_value_size) { 438 size_t offs = le16_to_cpu(last->e_value_offs); 439 if (offs < min_offs) 440 min_offs = offs; 441 } 442 last = next; 443 } 444 445 /* Check whether we have enough space left. */ 446 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32); 447 } else { 448 /* We will use a new extended attribute block. */ 449 free = sb->s_blocksize - 450 sizeof(struct ext2_xattr_header) - sizeof(__u32); 451 here = last = NULL; /* avoid gcc uninitialized warning. */ 452 } 453 454 if (not_found) { 455 /* Request to remove a nonexistent attribute? */ 456 error = -ENODATA; 457 if (flags & XATTR_REPLACE) 458 goto cleanup; 459 error = 0; 460 if (value == NULL) 461 goto cleanup; 462 } else { 463 /* Request to create an existing attribute? */ 464 error = -EEXIST; 465 if (flags & XATTR_CREATE) 466 goto cleanup; 467 if (!here->e_value_block && here->e_value_size) { 468 size_t size = le32_to_cpu(here->e_value_size); 469 470 if (le16_to_cpu(here->e_value_offs) + size > 471 sb->s_blocksize || size > sb->s_blocksize) 472 goto bad_block; 473 free += EXT2_XATTR_SIZE(size); 474 } 475 free += EXT2_XATTR_LEN(name_len); 476 } 477 error = -ENOSPC; 478 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len)) 479 goto cleanup; 480 481 /* Here we know that we can set the new attribute. */ 482 483 if (header) { 484 struct mb_cache_entry *ce; 485 486 /* assert(header == HDR(bh)); */ 487 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, 488 bh->b_blocknr); 489 lock_buffer(bh); 490 if (header->h_refcount == cpu_to_le32(1)) { 491 ea_bdebug(bh, "modifying in-place"); 492 if (ce) 493 mb_cache_entry_free(ce); 494 /* keep the buffer locked while modifying it. */ 495 } else { 496 int offset; 497 498 if (ce) 499 mb_cache_entry_release(ce); 500 unlock_buffer(bh); 501 ea_bdebug(bh, "cloning"); 502 header = kmalloc(bh->b_size, GFP_KERNEL); 503 error = -ENOMEM; 504 if (header == NULL) 505 goto cleanup; 506 memcpy(header, HDR(bh), bh->b_size); 507 header->h_refcount = cpu_to_le32(1); 508 509 offset = (char *)here - bh->b_data; 510 here = ENTRY((char *)header + offset); 511 offset = (char *)last - bh->b_data; 512 last = ENTRY((char *)header + offset); 513 } 514 } else { 515 /* Allocate a buffer where we construct the new block. */ 516 header = kzalloc(sb->s_blocksize, GFP_KERNEL); 517 error = -ENOMEM; 518 if (header == NULL) 519 goto cleanup; 520 end = (char *)header + sb->s_blocksize; 521 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC); 522 header->h_blocks = header->h_refcount = cpu_to_le32(1); 523 last = here = ENTRY(header+1); 524 } 525 526 /* Iff we are modifying the block in-place, bh is locked here. */ 527 528 if (not_found) { 529 /* Insert the new name. */ 530 size_t size = EXT2_XATTR_LEN(name_len); 531 size_t rest = (char *)last - (char *)here; 532 memmove((char *)here + size, here, rest); 533 memset(here, 0, size); 534 here->e_name_index = name_index; 535 here->e_name_len = name_len; 536 memcpy(here->e_name, name, name_len); 537 } else { 538 if (!here->e_value_block && here->e_value_size) { 539 char *first_val = (char *)header + min_offs; 540 size_t offs = le16_to_cpu(here->e_value_offs); 541 char *val = (char *)header + offs; 542 size_t size = EXT2_XATTR_SIZE( 543 le32_to_cpu(here->e_value_size)); 544 545 if (size == EXT2_XATTR_SIZE(value_len)) { 546 /* The old and the new value have the same 547 size. Just replace. */ 548 here->e_value_size = cpu_to_le32(value_len); 549 memset(val + size - EXT2_XATTR_PAD, 0, 550 EXT2_XATTR_PAD); /* Clear pad bytes. */ 551 memcpy(val, value, value_len); 552 goto skip_replace; 553 } 554 555 /* Remove the old value. */ 556 memmove(first_val + size, first_val, val - first_val); 557 memset(first_val, 0, size); 558 here->e_value_offs = 0; 559 min_offs += size; 560 561 /* Adjust all value offsets. */ 562 last = ENTRY(header+1); 563 while (!IS_LAST_ENTRY(last)) { 564 size_t o = le16_to_cpu(last->e_value_offs); 565 if (!last->e_value_block && o < offs) 566 last->e_value_offs = 567 cpu_to_le16(o + size); 568 last = EXT2_XATTR_NEXT(last); 569 } 570 } 571 if (value == NULL) { 572 /* Remove the old name. */ 573 size_t size = EXT2_XATTR_LEN(name_len); 574 last = ENTRY((char *)last - size); 575 memmove(here, (char*)here + size, 576 (char*)last - (char*)here); 577 memset(last, 0, size); 578 } 579 } 580 581 if (value != NULL) { 582 /* Insert the new value. */ 583 here->e_value_size = cpu_to_le32(value_len); 584 if (value_len) { 585 size_t size = EXT2_XATTR_SIZE(value_len); 586 char *val = (char *)header + min_offs - size; 587 here->e_value_offs = 588 cpu_to_le16((char *)val - (char *)header); 589 memset(val + size - EXT2_XATTR_PAD, 0, 590 EXT2_XATTR_PAD); /* Clear the pad bytes. */ 591 memcpy(val, value, value_len); 592 } 593 } 594 595 skip_replace: 596 if (IS_LAST_ENTRY(ENTRY(header+1))) { 597 /* This block is now empty. */ 598 if (bh && header == HDR(bh)) 599 unlock_buffer(bh); /* we were modifying in-place. */ 600 error = ext2_xattr_set2(inode, bh, NULL); 601 } else { 602 ext2_xattr_rehash(header, here); 603 if (bh && header == HDR(bh)) 604 unlock_buffer(bh); /* we were modifying in-place. */ 605 error = ext2_xattr_set2(inode, bh, header); 606 } 607 608 cleanup: 609 brelse(bh); 610 if (!(bh && header == HDR(bh))) 611 kfree(header); 612 up_write(&EXT2_I(inode)->xattr_sem); 613 614 return error; 615 } 616 617 /* 618 * Second half of ext2_xattr_set(): Update the file system. 619 */ 620 static int 621 ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh, 622 struct ext2_xattr_header *header) 623 { 624 struct super_block *sb = inode->i_sb; 625 struct buffer_head *new_bh = NULL; 626 int error; 627 628 if (header) { 629 new_bh = ext2_xattr_cache_find(inode, header); 630 if (new_bh) { 631 /* We found an identical block in the cache. */ 632 if (new_bh == old_bh) { 633 ea_bdebug(new_bh, "keeping this block"); 634 } else { 635 /* The old block is released after updating 636 the inode. */ 637 ea_bdebug(new_bh, "reusing block"); 638 639 error = dquot_alloc_block(inode, 1); 640 if (error) { 641 unlock_buffer(new_bh); 642 goto cleanup; 643 } 644 le32_add_cpu(&HDR(new_bh)->h_refcount, 1); 645 ea_bdebug(new_bh, "refcount now=%d", 646 le32_to_cpu(HDR(new_bh)->h_refcount)); 647 } 648 unlock_buffer(new_bh); 649 } else if (old_bh && header == HDR(old_bh)) { 650 /* Keep this block. No need to lock the block as we 651 don't need to change the reference count. */ 652 new_bh = old_bh; 653 get_bh(new_bh); 654 ext2_xattr_cache_insert(new_bh); 655 } else { 656 /* We need to allocate a new block */ 657 ext2_fsblk_t goal = ext2_group_first_block_no(sb, 658 EXT2_I(inode)->i_block_group); 659 int block = ext2_new_block(inode, goal, &error); 660 if (error) 661 goto cleanup; 662 ea_idebug(inode, "creating block %d", block); 663 664 new_bh = sb_getblk(sb, block); 665 if (unlikely(!new_bh)) { 666 ext2_free_blocks(inode, block, 1); 667 mark_inode_dirty(inode); 668 error = -ENOMEM; 669 goto cleanup; 670 } 671 lock_buffer(new_bh); 672 memcpy(new_bh->b_data, header, new_bh->b_size); 673 set_buffer_uptodate(new_bh); 674 unlock_buffer(new_bh); 675 ext2_xattr_cache_insert(new_bh); 676 677 ext2_xattr_update_super_block(sb); 678 } 679 mark_buffer_dirty(new_bh); 680 if (IS_SYNC(inode)) { 681 sync_dirty_buffer(new_bh); 682 error = -EIO; 683 if (buffer_req(new_bh) && !buffer_uptodate(new_bh)) 684 goto cleanup; 685 } 686 } 687 688 /* Update the inode. */ 689 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0; 690 inode->i_ctime = CURRENT_TIME_SEC; 691 if (IS_SYNC(inode)) { 692 error = sync_inode_metadata(inode, 1); 693 /* In case sync failed due to ENOSPC the inode was actually 694 * written (only some dirty data were not) so we just proceed 695 * as if nothing happened and cleanup the unused block */ 696 if (error && error != -ENOSPC) { 697 if (new_bh && new_bh != old_bh) { 698 dquot_free_block_nodirty(inode, 1); 699 mark_inode_dirty(inode); 700 } 701 goto cleanup; 702 } 703 } else 704 mark_inode_dirty(inode); 705 706 error = 0; 707 if (old_bh && old_bh != new_bh) { 708 struct mb_cache_entry *ce; 709 710 /* 711 * If there was an old block and we are no longer using it, 712 * release the old block. 713 */ 714 ce = mb_cache_entry_get(ext2_xattr_cache, old_bh->b_bdev, 715 old_bh->b_blocknr); 716 lock_buffer(old_bh); 717 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) { 718 /* Free the old block. */ 719 if (ce) 720 mb_cache_entry_free(ce); 721 ea_bdebug(old_bh, "freeing"); 722 ext2_free_blocks(inode, old_bh->b_blocknr, 1); 723 mark_inode_dirty(inode); 724 /* We let our caller release old_bh, so we 725 * need to duplicate the buffer before. */ 726 get_bh(old_bh); 727 bforget(old_bh); 728 } else { 729 /* Decrement the refcount only. */ 730 le32_add_cpu(&HDR(old_bh)->h_refcount, -1); 731 if (ce) 732 mb_cache_entry_release(ce); 733 dquot_free_block_nodirty(inode, 1); 734 mark_inode_dirty(inode); 735 mark_buffer_dirty(old_bh); 736 ea_bdebug(old_bh, "refcount now=%d", 737 le32_to_cpu(HDR(old_bh)->h_refcount)); 738 } 739 unlock_buffer(old_bh); 740 } 741 742 cleanup: 743 brelse(new_bh); 744 745 return error; 746 } 747 748 /* 749 * ext2_xattr_delete_inode() 750 * 751 * Free extended attribute resources associated with this inode. This 752 * is called immediately before an inode is freed. 753 */ 754 void 755 ext2_xattr_delete_inode(struct inode *inode) 756 { 757 struct buffer_head *bh = NULL; 758 struct mb_cache_entry *ce; 759 760 down_write(&EXT2_I(inode)->xattr_sem); 761 if (!EXT2_I(inode)->i_file_acl) 762 goto cleanup; 763 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 764 if (!bh) { 765 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 766 "inode %ld: block %d read error", inode->i_ino, 767 EXT2_I(inode)->i_file_acl); 768 goto cleanup; 769 } 770 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count))); 771 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 772 HDR(bh)->h_blocks != cpu_to_le32(1)) { 773 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 774 "inode %ld: bad block %d", inode->i_ino, 775 EXT2_I(inode)->i_file_acl); 776 goto cleanup; 777 } 778 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, bh->b_blocknr); 779 lock_buffer(bh); 780 if (HDR(bh)->h_refcount == cpu_to_le32(1)) { 781 if (ce) 782 mb_cache_entry_free(ce); 783 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1); 784 get_bh(bh); 785 bforget(bh); 786 unlock_buffer(bh); 787 } else { 788 le32_add_cpu(&HDR(bh)->h_refcount, -1); 789 if (ce) 790 mb_cache_entry_release(ce); 791 ea_bdebug(bh, "refcount now=%d", 792 le32_to_cpu(HDR(bh)->h_refcount)); 793 unlock_buffer(bh); 794 mark_buffer_dirty(bh); 795 if (IS_SYNC(inode)) 796 sync_dirty_buffer(bh); 797 dquot_free_block_nodirty(inode, 1); 798 } 799 EXT2_I(inode)->i_file_acl = 0; 800 801 cleanup: 802 brelse(bh); 803 up_write(&EXT2_I(inode)->xattr_sem); 804 } 805 806 /* 807 * ext2_xattr_put_super() 808 * 809 * This is called when a file system is unmounted. 810 */ 811 void 812 ext2_xattr_put_super(struct super_block *sb) 813 { 814 mb_cache_shrink(sb->s_bdev); 815 } 816 817 818 /* 819 * ext2_xattr_cache_insert() 820 * 821 * Create a new entry in the extended attribute cache, and insert 822 * it unless such an entry is already in the cache. 823 * 824 * Returns 0, or a negative error number on failure. 825 */ 826 static int 827 ext2_xattr_cache_insert(struct buffer_head *bh) 828 { 829 __u32 hash = le32_to_cpu(HDR(bh)->h_hash); 830 struct mb_cache_entry *ce; 831 int error; 832 833 ce = mb_cache_entry_alloc(ext2_xattr_cache, GFP_NOFS); 834 if (!ce) 835 return -ENOMEM; 836 error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash); 837 if (error) { 838 mb_cache_entry_free(ce); 839 if (error == -EBUSY) { 840 ea_bdebug(bh, "already in cache (%d cache entries)", 841 atomic_read(&ext2_xattr_cache->c_entry_count)); 842 error = 0; 843 } 844 } else { 845 ea_bdebug(bh, "inserting [%x] (%d cache entries)", (int)hash, 846 atomic_read(&ext2_xattr_cache->c_entry_count)); 847 mb_cache_entry_release(ce); 848 } 849 return error; 850 } 851 852 /* 853 * ext2_xattr_cmp() 854 * 855 * Compare two extended attribute blocks for equality. 856 * 857 * Returns 0 if the blocks are equal, 1 if they differ, and 858 * a negative error number on errors. 859 */ 860 static int 861 ext2_xattr_cmp(struct ext2_xattr_header *header1, 862 struct ext2_xattr_header *header2) 863 { 864 struct ext2_xattr_entry *entry1, *entry2; 865 866 entry1 = ENTRY(header1+1); 867 entry2 = ENTRY(header2+1); 868 while (!IS_LAST_ENTRY(entry1)) { 869 if (IS_LAST_ENTRY(entry2)) 870 return 1; 871 if (entry1->e_hash != entry2->e_hash || 872 entry1->e_name_index != entry2->e_name_index || 873 entry1->e_name_len != entry2->e_name_len || 874 entry1->e_value_size != entry2->e_value_size || 875 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len)) 876 return 1; 877 if (entry1->e_value_block != 0 || entry2->e_value_block != 0) 878 return -EIO; 879 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs), 880 (char *)header2 + le16_to_cpu(entry2->e_value_offs), 881 le32_to_cpu(entry1->e_value_size))) 882 return 1; 883 884 entry1 = EXT2_XATTR_NEXT(entry1); 885 entry2 = EXT2_XATTR_NEXT(entry2); 886 } 887 if (!IS_LAST_ENTRY(entry2)) 888 return 1; 889 return 0; 890 } 891 892 /* 893 * ext2_xattr_cache_find() 894 * 895 * Find an identical extended attribute block. 896 * 897 * Returns a locked buffer head to the block found, or NULL if such 898 * a block was not found or an error occurred. 899 */ 900 static struct buffer_head * 901 ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header) 902 { 903 __u32 hash = le32_to_cpu(header->h_hash); 904 struct mb_cache_entry *ce; 905 906 if (!header->h_hash) 907 return NULL; /* never share */ 908 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash); 909 again: 910 ce = mb_cache_entry_find_first(ext2_xattr_cache, inode->i_sb->s_bdev, 911 hash); 912 while (ce) { 913 struct buffer_head *bh; 914 915 if (IS_ERR(ce)) { 916 if (PTR_ERR(ce) == -EAGAIN) 917 goto again; 918 break; 919 } 920 921 bh = sb_bread(inode->i_sb, ce->e_block); 922 if (!bh) { 923 ext2_error(inode->i_sb, "ext2_xattr_cache_find", 924 "inode %ld: block %ld read error", 925 inode->i_ino, (unsigned long) ce->e_block); 926 } else { 927 lock_buffer(bh); 928 if (le32_to_cpu(HDR(bh)->h_refcount) > 929 EXT2_XATTR_REFCOUNT_MAX) { 930 ea_idebug(inode, "block %ld refcount %d>%d", 931 (unsigned long) ce->e_block, 932 le32_to_cpu(HDR(bh)->h_refcount), 933 EXT2_XATTR_REFCOUNT_MAX); 934 } else if (!ext2_xattr_cmp(header, HDR(bh))) { 935 ea_bdebug(bh, "b_count=%d", 936 atomic_read(&(bh->b_count))); 937 mb_cache_entry_release(ce); 938 return bh; 939 } 940 unlock_buffer(bh); 941 brelse(bh); 942 } 943 ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash); 944 } 945 return NULL; 946 } 947 948 #define NAME_HASH_SHIFT 5 949 #define VALUE_HASH_SHIFT 16 950 951 /* 952 * ext2_xattr_hash_entry() 953 * 954 * Compute the hash of an extended attribute. 955 */ 956 static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header, 957 struct ext2_xattr_entry *entry) 958 { 959 __u32 hash = 0; 960 char *name = entry->e_name; 961 int n; 962 963 for (n=0; n < entry->e_name_len; n++) { 964 hash = (hash << NAME_HASH_SHIFT) ^ 965 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^ 966 *name++; 967 } 968 969 if (entry->e_value_block == 0 && entry->e_value_size != 0) { 970 __le32 *value = (__le32 *)((char *)header + 971 le16_to_cpu(entry->e_value_offs)); 972 for (n = (le32_to_cpu(entry->e_value_size) + 973 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) { 974 hash = (hash << VALUE_HASH_SHIFT) ^ 975 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^ 976 le32_to_cpu(*value++); 977 } 978 } 979 entry->e_hash = cpu_to_le32(hash); 980 } 981 982 #undef NAME_HASH_SHIFT 983 #undef VALUE_HASH_SHIFT 984 985 #define BLOCK_HASH_SHIFT 16 986 987 /* 988 * ext2_xattr_rehash() 989 * 990 * Re-compute the extended attribute hash value after an entry has changed. 991 */ 992 static void ext2_xattr_rehash(struct ext2_xattr_header *header, 993 struct ext2_xattr_entry *entry) 994 { 995 struct ext2_xattr_entry *here; 996 __u32 hash = 0; 997 998 ext2_xattr_hash_entry(header, entry); 999 here = ENTRY(header+1); 1000 while (!IS_LAST_ENTRY(here)) { 1001 if (!here->e_hash) { 1002 /* Block is not shared if an entry's hash value == 0 */ 1003 hash = 0; 1004 break; 1005 } 1006 hash = (hash << BLOCK_HASH_SHIFT) ^ 1007 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^ 1008 le32_to_cpu(here->e_hash); 1009 here = EXT2_XATTR_NEXT(here); 1010 } 1011 header->h_hash = cpu_to_le32(hash); 1012 } 1013 1014 #undef BLOCK_HASH_SHIFT 1015 1016 int __init 1017 init_ext2_xattr(void) 1018 { 1019 ext2_xattr_cache = mb_cache_create("ext2_xattr", 6); 1020 if (!ext2_xattr_cache) 1021 return -ENOMEM; 1022 return 0; 1023 } 1024 1025 void 1026 exit_ext2_xattr(void) 1027 { 1028 mb_cache_destroy(ext2_xattr_cache); 1029 } 1030